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Sample records for latent heat release

  1. Satellite-observed latent heat release in a tropical cyclone

    NASA Technical Reports Server (NTRS)

    Adler, R. F.; Rodgers, E. B.

    1976-01-01

    Data from the Nimbus 5 electrically scanning microwave radiometer (ESMR) are used to make calculations of the latent heat release (L.H.R.) and the distribution of rainfall rate in a tropical cyclone as it grows from a tropical disturbance to a typhoon. The L.H.R. (calculated over a circular area of 4 deg latitude radius) increases during the development and intensification of the storm from a magnitude of 2.7 X 10 to the 21st power ergs/s (in the disturbance stage) to 8.8 X 10 to the 21st power ergs (typhoon stage). The latter value corresponds to a mean rainfall rate of 2.0 mm hr/s. The more intense the cyclone and the greater the L.H.R., the greater the percentage contribution of the larger rainfall rates to the L.H.R. In the disturbance stage the percentage contribution of rainfall rates less than or minus 6 mm hr/s is typically 8%; for the typhoon stage, the value is 38%. The distribution of rainfall rate as a function of radial distance from the center indicates that as the cyclone intensifies, the higher rainfall rates tend to concentrate toward the center of the circulation.

  2. Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Olson, W. S.; Meneghini, R.; Yang, S.; Simpson, J.; Kummerow, C.; Smith, E.

    2000-01-01

    This paper represents the first attempt to use TRMM rainfall information to estimate the four dimensional latent heating structure over the global tropics for February 1998. The mean latent heating profiles over six oceanic regions (TOGA COARE IFA, Central Pacific, S. Pacific Convergence Zone, East Pacific, Indian Ocean and Atlantic Ocean) and three continental regions (S. America, Central Africa and Australia) are estimated and studied. The heating profiles obtained from the results of diagnostic budget studies over a broad range of geographic locations are used to provide comparisons and indirect validation for the heating algorithm estimated heating profiles. Three different latent heating algorithms, the Goddard Convective-Stratiform (CSH) heating, the Goddard Profiling (GPROF) heating, and the Hydrometeor heating (HH) are used and their results are intercompared. The horizontal distribution or patterns of latent heat release from the three different heating retrieval methods are quite similar. They all can identify the areas of major convective activity (i.e., a well defined ITCZ in the Pacific, a distinct SPCZ) in the global tropics. The magnitude of their estimated latent heating release is also not in bad agreement with each other and with those determined from diagnostic budget studies. However, the major difference among these three heating retrieval algorithms is the altitude of the maximum heating level. The CSH algorithm estimated heating profiles only show one maximum heating level, and the level varies between convective activity from various geographic locations. These features are in good agreement with diagnostic budget studies. By contrast, two maximum heating levels were found using the GPROF heating and HH algorithms. The latent heating profiles estimated from all three methods can not show cooling between active convective events. We also examined the impact of different TMI (Multi-channel Passive Microwave Sensor) and PR (Precipitation Radar

  3. Effect of Melt Superheating Treatment on the Latent Heat Release of Sn

    NASA Astrophysics Data System (ADS)

    Xu, Junfeng; Dang, Bo; Fan, Dandan; Jian, Zengyun

    2016-12-01

    The accuracy of the baseline evaluation is of importance for calculating the transition enthalpy such as the latent heat of the crystallization. This study demonstrates the modified method of the equivalent non-latent heat baseline, by which the transition enthalpy can be measured accurately according to the transition peak in differential scanning calorimetric curve. With this method, the effect of melt superheating treatment time on the latent heat release upon the solidification of tin is investigated. The results show that the latent heat increases by increasing the treatment time, and is close to a constant when the treatment time is large enough, indicating the homogeneous system. And then, a simple model is established to describe the changes of the crystallization latent heat with the treatment time, which is confirmed by the experimental data of Sn.

  4. Effect of Melt Superheating Treatment on the Latent Heat Release of Sn

    NASA Astrophysics Data System (ADS)

    Xu, Junfeng; Dang, Bo; Fan, Dandan; Jian, Zengyun

    2017-03-01

    The accuracy of the baseline evaluation is of importance for calculating the transition enthalpy such as the latent heat of the crystallization. This study demonstrates the modified method of the equivalent non-latent heat baseline, by which the transition enthalpy can be measured accurately according to the transition peak in differential scanning calorimetric curve. With this method, the effect of melt superheating treatment time on the latent heat release upon the solidification of tin is investigated. The results show that the latent heat increases by increasing the treatment time, and is close to a constant when the treatment time is large enough, indicating the homogeneous system. And then, a simple model is established to describe the changes of the crystallization latent heat with the treatment time, which is confirmed by the experimental data of Sn.

  5. Latent Heating from TRMM Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Tao, W.; Takayabu, Y. N.; Shige, S.; Lang, S. E.; Olson, W. S.

    2012-12-01

    Rainfall production is a fundamental process within the Earth's hydrological cycle because it represents both a principal forcing term in surface water budgets, and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations within the Tropics - as well as modify the energetic efficiencies of mid-latitude weather systems. This paper highlights the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission (TRMM) satellite observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional account of rainfall over the global Tropics and sub-tropics - information which can be used to estimate the space-time structure of latent heating across the Earth's low latitudes. A set of algorithm methodologies has been developed to estimate latent heating based on rain rate profile retrievals obtained from TRMM measurements. These algorithms are briefly described followed by a discussion of the foremost latent heating products that can be generated from them. The investigation then provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  6. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Smith, E. A.; Adler, R.; Haddad, Z.; Hou, A.; Iguchi, T.; Kakar, R.; Krishnamurti, T.; Kummerow, C.; Lang, S.

    2004-01-01

    Rainfall production is the fundamental variable within the Earth's hydrological cycle because it is both the principal forcing term in surface water budgets and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations within the tropics - as well as modifying the energetic efficiencies of midlatitude weather systems. This paper focuses on the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission (TRMM) satellite observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional account of rainfall over the global tropics and sub-tropics, information which can be used to estimate the space-time structure of latent heating across the Earth's low latitudes. The paper examines how the observed TRMM distribution of rainfall has advanced an understanding of the global water and energy cycle and its consequent relationship to the atmospheric general circulation and climate via latent heat release. A set of algorithm methodologies that are being used to estimate latent heating based on rain rate retrievals from the TRMM observations are described. The characteristics of these algorithms and the latent heating products that can be generated from them are also described, along with validation analyses of the heating products themselves. Finally, the investigation provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  7. The application of satellite data to study the effects of latent heat release on cyclones

    NASA Technical Reports Server (NTRS)

    Clark, J. H. E.

    1984-01-01

    Generalized energetics were studied for nonlinear inviscid symmetric instability (SI). It was found that the linear theory fails to predict the stability in certain cases where the basic state is transitional between stability and instability. The initial growth of the SI perturbations can be fairly well approximated by linear theory, but the long time nonlinear evaluations will be bonded energetically if the SI region is finite. However, a further extension of the energetics to conditional symmetric instability (CSI) shows that the nonlinear evolution of circulation will energetically depend much more on the precipitation in a complicated way. By treating the latent heat as a source which is implicitly related to the motion field, the existence, uniqueness and stability of steady viscous (CSI) circulations are studied. Viscous CSI circulations are proved to be unique and asymptotically stable when the heat sources are weak and less sensitive to the motion perturbations. By considering the fact that moist updrafts are narrow and using eddy viscosity of 0(1,000 m squared/s) the stability criterion suggests that some frontal rainbands were probably dominated by the CSI mechanism even in their mature quasi-steady stage.

  8. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Smith, E.; Olson, W.

    2005-01-01

    Rainfall production is a fundamental process within the Earth;s hydrological cycle because it represents both a principal forcing term in surface water budgets, and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations with the Tropics - as well as modify the energetic efficiencies of mid-latitude weather systems. This paper highlights the retrieval of observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional amount of rainfall over the global Tropics and sub-tropics - information which can be used to estimate the spacetime structure of latent heating across the Earth's low latitudes. A set of algorithm methodologies has and continues to be developed to estimate latent heating based on rain rate profile retrievals obtained from TRMM measurements. These algorithms are briefly described followed by a discussion of the foremost latent heating products that can be generate from them. The investigation then provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  9. Re-examining the roles of surface heat flux and latent heat release in a "hurricane-like" polar low over the Barents Sea

    NASA Astrophysics Data System (ADS)

    Kolstad, Erik W.; Bracegirdle, Thomas J.; Zahn, Matthias

    2016-07-01

    Polar lows are intense mesoscale cyclones that occur at high latitudes in both hemispheres during winter. Their sometimes evidently convective nature, fueled by strong surface fluxes and with cloud-free centers, have led to some polar lows being referred to as "arctic hurricanes." Idealized studies have shown that intensification by hurricane development mechanisms is theoretically possible in polar winter atmospheres, but the lack of observations and realistic simulations of actual polar lows have made it difficult to ascertain if this occurs in reality. Here the roles of surface heat fluxes and latent heat release in the development of a Barents Sea polar low, which in its cloud structures showed some similarities to hurricanes, are studied with an ensemble of sensitivity experiments, where latent heating and/or surface fluxes of sensible and latent heat were switched off before the polar low peaked in intensity. To ensure that the polar lows in the sensitivity runs did not track too far away from the actual environmental conditions, a technique known as spectral nudging was applied. This was shown to be crucial for enabling comparisons between the different model runs. The results presented here show that (1) no intensification occurred during the mature, postbaroclinic stage of the simulated polar low; (2) surface heat fluxes, i.e., air-sea interaction, were crucial processes both in order to attain the polar low's peak intensity during the baroclinic stage and to maintain its strength in the mature stage; and (3) latent heat release played a less important role than surface fluxes in both stages.

  10. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. Additional information is included in the original extended abstract.

  11. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs. S. America ) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model. Review of other latent heating algorithms will be discussed in the workshop.

  12. Vertical Profiles of Latent Heat Release over the Global Tropics Using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in straitform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMXX), Brazil in 1999 (TRMM- LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  13. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM rainfall products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2001. Rainfall, latent heating and radar reflectivity structures between El Nino (DE 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs. west Pacific, Africa vs. S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in strtaiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  14. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  15. The effect of latent heat release on synoptic-to-planetary wave interactions and its implication for satellite observations: Theoretical modeling

    NASA Technical Reports Server (NTRS)

    Branscome, Lee E.; Bleck, Rainer

    1989-01-01

    Simple models are being developed to simulate interaction of planetary and synoptic-scale waves incorporating the effects of large-scale topography; eddy heat and momentum fluxes (or nonlinear dynamics); radiative heating/cooling; and latent heat release (precipitation) in synoptic-scale waves. The importance of latent heat release is determined in oceanic storm tracks for temporal variability and time-mean behavior of planetary waves. The model results were compared with available observations of planetary and synoptic-scale wave variability and time-mean circulation. The usefulness of monitoring precipitation in oceanic storm tracks by satellite observing systems was ascertained. The modeling effort includes two different low-order quasi-geostrophic models-time-dependent version and climatological mean version. The modeling also includes a low-order primitive equation model. A time-dependent, multi-level version will be used to validate the two-level Q-G models and examine effects of spherical geometry.

  16. Non-quasi-geostrophic effects in baroclinic waves with latent heat release

    NASA Technical Reports Server (NTRS)

    Fichtl, G. H.; Tang, C.-M.

    1984-01-01

    A study is conducted for the non-quasi-geostrophic baroclinic wave effects in a saturated atmosphere whose vertical motion is subject to pseudo-adiabatic processes. With respect to the characteristics of energetics for the first-order solution, it is noted that, in the cases of both the dry mode and the first moist mode, the heat transport quantities due to the second-order eddy are small and opposite in sign to their respective transports. The non-quasi-geostrophic effects render the vertical motion field asymmetric in each of the regions involved and enter into the present treatment only as nonlinear terms. The moisture transport terms in the eddy-available potential energy equation is small by comparison to other individual terms in the cyclone scale motion's energetics calculation. This is consistent with the observational results of Smith (1980).

  17. Understanding Latent Heat of Vaporization.

    ERIC Educational Resources Information Center

    Linz, Ed

    1995-01-01

    Presents a simple exercise for students to do in the kitchen at home to determine the latent heat of vaporization of water using typical household materials. Designed to stress understanding by sacrificing precision for simplicity. (JRH)

  18. Latent heat of vehicular motion

    NASA Astrophysics Data System (ADS)

    Ahmadi, Farzad; Berrier, Austin; Habibi, Mohammad; Boreyko, Jonathan

    2016-11-01

    We have used the thermodynamic concept of latent heat, where a system loses energy due to a solid-to-liquid phase transition, to study the flow of a group of vehicles moving from rest. During traffic flow, drivers keep a large distance from the car in front of them to ensure safe driving. When a group of cars comes to a stop, for example at a red light, drivers voluntarily induce a "phase transition" from this "liquid phase" to a close-packed "solid phase." This phase transition is motivated by the intuition that maximizing displacement before stopping will minimize the overall travel time. To test the effects of latent heat on flow efficiency, a drone captured the dynamics of cars flowing through an intersection on a Smart Road where the initial spacing between cars at the red light was systematically varied. By correlating the experimental results with the Optimal Velocity Model (OVM), we find that the convention of inducing phase transitions at intersections offers no benefit, as the lag time (latent heat) of resumed flow offsets the initial increase in displacement. These findings suggest that in situations where gridlock is not an issue, drivers should not decrease their spacing during stoppages in order to maximize safety with no loss in flow efficiency.

  19. Retrieved Latent Heating from TRMM

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Smith, Eric A.; Houze Jr, Robert

    2008-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of precipitation formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the tropics with the associated latent heating (LH) accounting for three-fourths of the total heat energy available to the Earth's atmosphere. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. In the last decade, it has been established that standard products of LH from satellite measurements, particularly TRMM measurements, would be a valuable resource for scientific research and applications. Such products would enable new insights and investigations concerning the complexities of convection system life cycles, the diabatic heating controls and feedbacks related to meso-synoptic circulations and their forecasting, the relationship of tropical patterns of LH to the global circulation and climate, and strategies for improving cloud parameterizations in environmental prediction models. The status of retrieved TRMM LH products, TRMM LH inter-comparison and validation project, current TRMM LH applications and critic issues/action items (based on previous five TRMM LH workshops) is presented in this article.

  20. The effect of latent heat release on synoptic-to-planetary wave interactions and its implication for satellite observations: Theoretical modeling

    NASA Technical Reports Server (NTRS)

    Branscome, Lee E.; Bleck, Rainer; Obrien, Enda

    1990-01-01

    The project objectives are to develop process models to investigate the interaction of planetary and synoptic-scale waves including the effects of latent heat release (precipitation), nonlinear dynamics, physical and boundary-layer processes, and large-scale topography; to determine the importance of latent heat release for temporal variability and time-mean behavior of planetary and synoptic-scale waves; to compare the model results with available observations of planetary and synoptic wave variability; and to assess the implications of the results for monitoring precipitation in oceanic-storm tracks by satellite observing systems. Researchers have utilized two different models for this project: a two-level quasi-geostrophic model to study intraseasonal variability, anomalous circulations and the seasonal cycle, and a 10-level, multi-wave primitive equation model to validate the two-level Q-G model and examine effects of convection, surface processes, and spherical geometry. It explicitly resolves several planetary and synoptic waves and includes specific humidity (as a predicted variable), moist convection, and large-scale precipitation. In the past year researchers have concentrated on experiments with the multi-level primitive equation model. The dynamical part of that model is similar to the spectral model used by the National Meteorological Center for medium-range forecasts. The model includes parameterizations of large-scale condensation and moist convection. To test the validity of results regarding the influence of convective precipitation, researchers can use either one of two different convective schemes in the model, a Kuo convective scheme or a modified Arakawa-Schubert scheme which includes downdrafts. By choosing one or the other scheme, they can evaluate the impact of the convective parameterization on the circulation. In the past year researchers performed a variety of initial-value experiments with the primitive-equation model. Using initial

  1. Vertical Profiles of Latent Heat Release and Their Retrieval for TOGA COARE Convective Systems Using a Cloud Resolving Model, SSM/I, and Ship-borne Radar Data

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, S.; Simpson, J.; Olson, W. S.; Johnson, D.; Ferrier, B.; Kummerow, C.; Adler, R.

    1999-01-01

    Latent heating profiles associated with three (TOGA COARE) Tropical Ocean and Global Atmosphere Coupled Ocean Atmosphere Response Experiment active convective episodes (December 10-17 1992; December 19-27 1992; and February 9-13 1993) are examined using the Goddard Cumulus Ensemble (GCE) Model and retrieved by using the Goddard Convective and Stratiform Heating (CSH) algorithm . The following sources of rainfall information are input into the CSH algorithm: Special Sensor Microwave Imager (SSM/1), Radar and the GCE model. Diagnostically determined latent heating profiles calculated using 6 hourly soundings are used for validation. The GCE model simulated rainfall and latent heating profiles are in excellent agreement with those estimated by soundings. In addition, the typical convective and stratiform heating structures (or shapes) are well captured by the GCE model. Radar measured rainfall is smaller than that both estimated by the GCE model and SSM/I in all three different COARE IFA periods. SSM/I derived rainfall is more than the GCE model simulated for the December 19-27 and February 9-13 periods, but is in excellent agreement with the GCE model for the December 10-17 period. The GCE model estimated stratiform amount is about 50% for December 19-27, 42% for December 11-17 and 56% for the February 9-13 case. These results are consistent with large-scale analyses. The accurate estimates of stratiform amount is needed for good latent heating retrieval. A higher (lower) percentage of stratiform rain can imply a maximum heating rate at a higher (lower) altitude. The GCE model always simulates more stratiform rain (10 to 20%) than the radar for all three convective episodes. SSM/I derived stratiform amount is about 37% for December 19-27, 48% for December 11-17 and 41% for the February 9-13 case. Temporal variability of CSH algorithm retrieved latent heating profiles using either GCE model simulated or radar estimated rainfall and stratiform amount is in good

  2. Latent heat effects in subsurface heat transport modelling and their impact on palaeotemperature reconstructions

    NASA Astrophysics Data System (ADS)

    Mottaghy, Darius; Rath, Volker

    2006-01-01

    In cold regions the thermal regime is strongly affected by freezing or melting processes, consuming or releasing large amounts of latent heat. This changes enthalpy by orders of magnitude. We present a numerical approach for the implementation of these effects into a 3-D finite-difference heat transport model. The latent heat effect can be handled by substituting an apparent heat capacity for the volumetric heat capacity of unfrozen soil in the heat transfer equation. The model is verified by the analytical solution of the heat transport equation including phase change. We found significant deviations of temperature profiles when applying the latent heat effect on forward calculations of deep temperature logs. Ground surface temperature histories derived from synthetic data and field data from NE Poland underline the importance of considering freezing processes. In spite of its limitations, the proposed method is appropriate for the study of long-period climatic changes.

  3. Targeting latent TGFβ release in muscular dystrophy.

    PubMed

    Ceco, Ermelinda; Bogdanovich, Sasha; Gardner, Brandon; Miller, Tamari; DeJesus, Adam; Earley, Judy U; Hadhazy, Michele; Smith, Lucas R; Barton, Elisabeth R; Molkentin, Jeffery D; McNally, Elizabeth M

    2014-10-22

    Latent transforming growth factor-β (TGFβ) binding proteins (LTBPs) bind to inactive TGFβ in the extracellular matrix. In mice, muscular dystrophy symptoms are intensified by a genetic polymorphism that changes the hinge region of LTBP, leading to increased proteolytic susceptibility and TGFβ release. We have found that the hinge region of human LTBP4 was also readily proteolysed and that proteolysis could be blocked by an antibody to the hinge region. Transgenic mice were generated to carry a bacterial artificial chromosome encoding the human LTBP4 gene. These transgenic mice displayed larger myofibers, increased damage after muscle injury, and enhanced TGFβ signaling. In the mdx mouse model of Duchenne muscular dystrophy, the human LTBP4 transgene exacerbated muscular dystrophy symptoms and resulted in weaker muscles with an increased inflammatory infiltrate and greater LTBP4 cleavage in vivo. Blocking LTBP4 cleavage may be a therapeutic strategy to reduce TGFβ release and activity and decrease inflammation and muscle damage in muscular dystrophy.

  4. Dish-mounted latent heat buffer storage

    NASA Technical Reports Server (NTRS)

    Manvi, R.

    1981-01-01

    Dish-mounted latent heat storage subsystems for Rankine, Brayton, and Stirling engines operating at 427 C, 816 C, and 816 C respectively are discussed. Storage requirements definition, conceptual design, media stability and compatibility tests, and thermal performance analyses are considered.

  5. Latent Heat in Soil Heat Flux Measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  6. Latent Work and Latent Heat of the Liquid/Vapor Transformation

    DTIC Science & Technology

    2014-08-01

    latent heat and latent work of liquid/vapor phase transformation for variously constrained thermodynamic processes . thermodynamics, phase...1. Introduction 1 2. Latent Heat and Work of Thermodynamic Process 3 3. Equations of Phase Equilibrium 5 4. Vaporization/Condensation under Fixed...between the phase in the process of vaporization/condensation. Thermodynamical identities allow one to express p, T, and µ in terms of the derivatives of

  7. Determination of the Latent Heats and Triple Point of Perfluorocyclobutane

    ERIC Educational Resources Information Center

    Briggs, A. G.; Strachan, A. N.

    1977-01-01

    Proposes the use of Perfluorocyclobutane in physical chemistry courses to conduct experiments on latent heat, triple point temperatures and pressures, boiling points, and entropy of vaporization. (SL)

  8. Sensitivity of Latent Heating Profiles to Environmental Conditions: Implications for TRMM and Climate Research

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The Tropical Rainfall Measuring Mission (TRMM) as a part of NASA's Earth System Enterprise is the first mission dedicated to measuring tropical rainfall through microwave and visible sensors, and includes the first spaceborne rain radar. Tropical rainfall comprises two-thirds of global rainfall. It is also the primary distributor of heat through the atmosphere's circulation. It is this circulation that defines Earth's weather and climate. Understanding rainfall and its variability is crucial to understanding and predicting global climate change. Weather and climate models need an accurate assessment of the latent heating released as tropical rainfall occurs. Currently, cloud model-based algorithms are used to derive latent heating based on rainfall structure. Ultimately, these algorithms can be applied to actual data from TRMM. This study investigates key underlying assumptions used in developing the latent heating algorithms. For example, the standard algorithm is highly dependent on a system's rainfall amount and structure. It also depends on an a priori database of model-derived latent heating profiles based on the aforementioned rainfall characteristics. Unanswered questions remain concerning the sensitivity of latent heating profiles to environmental conditions (both thermodynamic and kinematic), regionality, and seasonality. This study investigates and quantifies such sensitivities and seeks to determine the optimal latent heating profile database based on the results. Ultimately, the study seeks to produce an optimized latent heating algorithm based not only on rainfall structure but also hydrometeor profiles.

  9. Solar thermoelectricity via advanced latent heat storage

    NASA Astrophysics Data System (ADS)

    Olsen, M. L.; Rea, J.; Glatzmaier, G. C.; Hardin, C.; Oshman, C.; Vaughn, J.; Roark, T.; Raade, J. W.; Bradshaw, R. W.; Sharp, J.; Avery, A. D.; Bobela, D.; Bonner, R.; Weigand, R.; Campo, D.; Parilla, P. A.; Siegel, N. P.; Toberer, E. S.; Ginley, D. S.

    2016-05-01

    We report on a new modular, dispatchable, and cost-effective solar electricity-generating technology. Solar ThermoElectricity via Advanced Latent heat Storage (STEALS) integrates several state-of-the-art technologies to provide electricity on demand. In the envisioned STEALS system, concentrated sunlight is converted to heat at a solar absorber. The heat is then delivered to either a thermoelectric (TE) module for direct electricity generation, or to charge a phase change material for thermal energy storage, enabling subsequent generation during off-sun hours, or both for simultaneous electricity production and energy storage. The key to making STEALS a dispatchable technology lies in the development of a "thermal valve," which controls when heat is allowed to flow through the TE module, thus controlling when electricity is generated. The current project addresses each of the three major subcomponents, (i) the TE module, (ii) the thermal energy storage system, and (iii) the thermal valve. The project also includes system-level and techno- economic modeling of the envisioned integrated system and will culminate in the demonstration of a laboratory-scale STEALS prototype capable of generating 3kWe.

  10. Solar Thermoelectricity via Advanced Latent Heat Storage

    SciTech Connect

    Olsen, Michele L.; Rea, J.; Glatzmaier, Greg C.; Hardin, C.; Oshman, C.; Vaughn, J.; Roark, T.; Raade, J. W.; Bradshaw, R. W.; Sharp, J.; Avery, Azure D.; Bobela, David; Bonner, R.; Weigand, R.; Campo, D.; Parilla, Philip A.; Siegel, N. P.; Toberer, Eric S.; Ginley, David S.

    2016-05-31

    We report on a new modular, dispatchable, and cost-effective solar electricity-generating technology. Solar ThermoElectricity via Advanced Latent heat Storage (STEALS) integrates several state-of-the-art technologies to provide electricity on demand. In the envisioned STEALS system, concentrated sunlight is converted to heat at a solar absorber. The heat is then delivered to either a thermoelectric (TE) module for direct electricity generation, or to charge a phase change material for thermal energy storage, enabling subsequent generation during off-sun hours, or both for simultaneous electricity production and energy storage. The key to making STEALS a dispatchable technology lies in the development of a 'thermal valve,' which controls when heat is allowed to flow through the TE module, thus controlling when electricity is generated. The current project addresses each of the three major subcomponents, (i) the TE module, (ii) the thermal energy storage system, and (iii) the thermal valve. The project also includes system-level and techno- economic modeling of the envisioned integrated system and will culminate in the demonstration of a laboratory-scale STEALS prototype capable of generating 3kWe.

  11. Latent Heating Retrievals Using the TRMM Precipitation Radar: A Multi-Seasonal Study

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, S.; Meneghini, R.; Halverson, J.; Johnson, R.; Simpson, J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. Present largescale weather and climate models can simulate latent heat release only crudely, thus reducing their confidence in predictions on both global and regional scales. This paper represents the first attempt to use NASA Tropical Rainfall Measuring Mission (TRMM) rainfall information to estimate the four-dimensional structure of global monthly latent heating profiles over the global tropics from December 1997 to October 2000. The Goddard Convective-Stratiform. Heating (CSH) algorithm and TRMM precipitation radar data are used for this study. We will examine and compare the latent heating structures between 1997-1998 (winter) ENSO and 1998-2000 (non-ENSO). We will also examine over the tropics. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental; Indian oceans vs west Pacific; Africa vs S. America) will be also examined and compared. In addition, we will examine the relationship between latent heating (max heating level) and SST. The period of interest also coincides with several TRMM field campaigns that recently occurred over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and in the central Pacific in 1999 (KWAJEX). Sounding diagnosed Q1 budgets from these experiments could provide a means of validating the retrieved profiles of latent heating from the CSH algorithm.

  12. The effective latent heat of aqueous nanofluids

    NASA Astrophysics Data System (ADS)

    Lee, Soochan; Taylor, Robert A.; Dai, Lenore; Prasher, Ravi; Phelan, Patrick E.

    2015-06-01

    Nanoparticle suspensions, popularly termed ‘nanofluids’, have been extensively investigated for their thermal and radiative properties (Eastman et al 1996 Mater. Res. Soc. Proc. 457; Keblinski et al 2005 Mater. Today 8 36-44 Barber et al 2011 Nanoscale Res. Lett. 6 1-13 Thomas and Sobhan 2011 Nanoscale Res. Lett. 6 1-21 Taylor et al 2011 Nanoscale Res. Lett. 6 1-11 Fang et al 2013 Nano Lett. 13 1736-42 Otanicar et al 2010 J. Renew. Sustainable Energy 2 03310201-13 Prasher et al 2006 ASME J. Heat Transfer 128 588-95 Shin and Banerjee 2011 ASME J. Heat Transfer 133 1-4 Taylor and Phelan 2009 Int. J. Heat Mass Transfer 52 5339-48 Ameen et al 2010 Int. J. Thermophys. 31 1131-44 Lee et al 2014 Appl. Phys. Lett. 104 1-4). Such work has generated great controversy, although it is (arguably) generally accepted today that the presence of nanoparticles rarely leads to useful enhancements in either thermal conductivity or convective heat transfer. On the other hand, there are still examples of unanticipated enhancements to some properties, such as the specific heat of molten salt-based nanofluids reported by Shin and Banerjee (2011 ASME J. Heat Transfer 133 1-4) and the critical heat flux mentioned by Taylor and Phelan (2009 Int. J. Heat Mass Transfer 52 5339-48). Another largely overlooked example is the reported effect of nanoparticles on the effective latent heat of vaporization (hfg) of aqueous nanofluids, as reported by Ameen et al (2010 Int. J. Thermophys. 31 1131-44). Through molecular dynamics (MD) modeling supplemented with limited experimental data they found that hfg increases with increasing nanoparticle concentration, for Pt nanoparticles (MD) and Al2O3 nanoparticles (experiments). Here, we extend those exploratory experiments in an effort to determine if hfg of aqueous nanofluids can be manipulated, i.e., increased or decreased by the addition of graphite or silver nanoparticles. Our results to date indicate that, yes, hfg can be substantially impacted, by

  13. Retrieval of Latent Heating from TRMM Measurements

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Smith, E. A.; Adler, R. F.; Hou, A. Y.; Meneghini, R.; Simpson, J.; Haddad, Z. S.; Iguchi, T.; Satoh, S.; Kakar, R.; Krishnamurti, T. N.; Kummerow, C. D.; Lang, S.; Nakamura, K.; Nakazawa, T.; Okamoto, K.; Shige, S.; Olson, W. S.; Takayabu, Y.; Tripoli, G. J.; Yang, S.

    2006-01-01

    Precipitation, in driving the global hydrological cycle, strongly influences the behavior of the Earth's weather and climate systems and is central to their variability. Two-thirds of the global rainfall occurs over the Tropics, which leads to its profound effect on the general circulation of the atmosphere. This is because its energetic equivalent, latent heating (LH), is the tropical convective heat engine's primary fuel source as originally emphasized by Riehl and Malkus (1958). At low latitudes, LH stemming from extended bands of rainfall modulates large-scale zonal and meridional circulations and their consequent mass overturnings (e.g., Hartmann et al. 1984; Hack and Schubert 1990). Also, LH is the principal energy source in the creation, growth, vertical structure, and propagation of long-lived tropical waves (e.g., Puri 1987; Lau and Chan 1988). Moreover, the distinct vertical distribution properties of convective and stratiform LH profiles help influence climatic outcomes via their tight control on large-scale circulations (Lau and Peng 1987; Nakazawa 1988; Sui and Lau 1988; Emanuel et al. 1994; Yanai et al. 2000; Sumi and Nakazawa 2002; Schumacher et al. 2004). The purpose of this paper is to describe how LH profiles are being derived from satellite precipitation rate retrievals, focusing on those being made with Tropical Rainfall Measuring Mission (TRMM) satellite measurements.

  14. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    NASA Technical Reports Server (NTRS)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  15. A solar air collector with integrated latent heat thermal storage

    NASA Astrophysics Data System (ADS)

    Charvat, Pavel; Ostry, Milan; Mauder, Tomas; Klimes, Lubomir

    2012-04-01

    Simulations of the behaviour of a solar air collector with integrated latent heat thermal storage were performed. The model of the collector was created with the use of coupling between TRNSYS 17 and MATLAB. Latent heat storage (Phase Change Material - PCM) was integrated with the solar absorber. The model of the latent heat storage absorber was created in MATLAB and the model of the solar air collector itself was created in TRNSYS with the use of TYPE 56. The model of the latent heat storage absorber allows specification of the PCM properties as well as other parameters. The simulated air collector was the front and back pass collector with the absorber in the middle of the air cavity. Two variants were considered for comparison; the light-weight absorber made of sheet metal and the heat-storage absorber with the PCM. Simulations were performed for the climatic conditions of the Czech Republic (using TMY weather data).

  16. High temperature active heat exchanger research for latent heat storage

    NASA Astrophysics Data System (ADS)

    Alario, J.; Haslett, R.

    1982-02-01

    An active heat exchange method in a latent heat (salt) thermal energy storage system that prevents a low conductivity solid salt layer from forming on heat transfer surfaces was developed. An evaluation of suitable media with melting points in the temperature range of interest (250 to 400 C) limited the candidates to molten salts from the chloride, hydroxide and nitrate families, based on high storage capacity, good corrosion characteristics and availability in large quantities at reasonable cost. The specific salt recommended for laboratory tests was a choride eutectic (20.5KCL o 24.5NaCL o 55.MgCl2% by wt.), with a nominal melting point of 385 C. Various active heat exchange concepts were given a technical and economic comparison to a passive tube shell design for a reference application (300 MW sub t for 6 hours). Test hardware was then built for the most promising concept: a direct contact heat exchanger in which molten salt droplets are injected into a cooler counter flowing stream of liquid metal carrier fluid (lead/Bismuth).

  17. Sensible and latent heat forced divergent circulations in the West African Monsoon System

    NASA Astrophysics Data System (ADS)

    Hagos, S.; Zhang, C.

    2008-12-01

    Field properties of divergent circulation are utilized to identify the roles of various diabatic processes in forcing moisture transport in the dynamics of the West African Monsoon and its seasonal cycle. In this analysis, the divergence field is treated as a set of point sources and is partitioned into two sub-sets corresponding to latent heat release and surface sensible heat flux at each respective point. The divergent circulation associated with each set is then calculated from the Poisson's equation using Gauss-Seidel iteration. Moisture transport by each set of divergent circulation is subsequently estimated. The results show different roles of the divergent circulations forced by surface sensible and latent heating in the monsoon dynamics. Surface sensible heating drives a shallow meridional circulation, which transports moisture deep into the continent at the polar side of the monsoon rain band and thereby promotes the seasonal northward migration of monsoon precipitation during the monsoon onset season. In contrast, the circulation directly associated with latent heating is deep and the corresponding moisture convergence is within the region of precipitation. Latent heating also induces dry air advection from the north. Neither effect promotes the seasonal northward migration of precipitation. The relative contributions of the processes associated with latent and sensible heating to the net moisture convergence, and hence the seasonal evolution of monsoon precipitation, depend on the background moisture.

  18. Power generation by exchange of latent heats of phase transition

    SciTech Connect

    Ehrlich, S.; Levenson, W.L.

    1981-08-11

    A power system is provided that uses the latent heat of fusion of water to raise the potential energy of a working fluid to a level that upon release generates power, preferably electrical power. The system is self-sustaining except for the energy that is supplied in water entering the system. The inlet water can be at any temperature within its liquid range under atmospheric or super atmospheric pressure, can advantageously contain the sensible waste heat typical of effluent from fossil fuel or nuclear power plants, can be relatively pure or be contaminated as with sewage or be the medium of a colloidal suspension, or consist of marine or other saline waters. In every case, purification of the water by freezing, for example, desalination, is accomplished without additional power consumption. A selected working fluid that boils at a temperature substantially below the freezing point of water is brought in the liquid state into contact with the water or other aqueous medium, causing the water to freeze and the working fluid to vaporize under pressure; the produced ice is removed; a portion of the so-produced ice is admixed with a eutectic forming salt to create a cooling medium at a temperature below the condensation temperature of the cooling fluid; the working-fluid vapors are preferably superheated by inlet aqueous medium and are released from autogenic elevated pressure to drive a turbine. Working fluid vapors are condensed by said cooling medium and returned by pumping into contact with inlet aqueous medium.

  19. The surface latent heat flux anomalies related to major earthquake

    NASA Astrophysics Data System (ADS)

    Jing, Feng; Shen, Xuhui; Kang, Chunli; Xiong, Pan; Hong, Shunying

    2011-12-01

    SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed etc. There is a sharp difference between the ocean surface and the land surface. Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed using SLHF data by STD (standard deviation) threshold method. It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy change process about earthquake preparation, that is, weak-strong-weak-disappeared.

  20. A Latent Heat Retrieval and its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part I: The Algorithm and Observations.

    NASA Technical Reports Server (NTRS)

    Guimond, Stephen R.; Bourassa, mark A.; Reasor, Paul D.

    2011-01-01

    The release of latent heat in clouds is an essential part of the formation and I intensification ohurricanes. The community knows very little about the intensity and structure of latent heating due largely to inadequate observations. In this paper, a new method for retrieving the latent heating field in hurricanes from airborne Dopple radar is presented and fields from rapidly intensifying Hurricane Guillermo (1997) are shown.

  1. Design and simulation of latent heat storage units

    SciTech Connect

    Shamsundar, N.; Stein, E.; Rooz, E.; Bascaran, E.; Lee, T.C. )

    1992-04-01

    This report presents the results of two years of research and development on passive latent heat storage systems. Analytical models have been developed and extended, and a computer code for simulating the performance of a latent heat storage has been developed. The code is intended to be merged into a larger solar energy system simulation code and used for making realistic system studies. Simulation studies using a code which has a flexible and accurate routine for handling the storage subsystem should lead to the development of better systems than those in which storage is added on after the rest of the system has already been selected and optimized.

  2. Design and simulation of latent heat storage units. Final report

    SciTech Connect

    Shamsundar, N.; Stein, E.; Rooz, E.; Bascaran, E.; Lee, T.C.

    1992-04-01

    This report presents the results of two years of research and development on passive latent heat storage systems. Analytical models have been developed and extended, and a computer code for simulating the performance of a latent heat storage has been developed. The code is intended to be merged into a larger solar energy system simulation code and used for making realistic system studies. Simulation studies using a code which has a flexible and accurate routine for handling the storage subsystem should lead to the development of better systems than those in which storage is added on after the rest of the system has already been selected and optimized.

  3. Filled Carbon Nanotubes: Superior Latent Heat Storage Enhancers

    SciTech Connect

    2009-04-01

    This factsheet describes a rstudy whose technical objective is to demonstrate the feasibility of filled carbon nanotubes (CNT) as latent heat storage enhancers, with potential applications as next generation thermal management fluids in diverse applications in industries ranging from high-demand microelectronic cooling, manufacturing, power generation, transportation, to solar energy storage.

  4. Latent heat and cyclone activity in the South Pacific, 10-18 January 1979

    NASA Technical Reports Server (NTRS)

    Miller, B. L.; Vincent, D. G.; Kann, D. M.; Robertson, Franklin R.

    1986-01-01

    This paper examines the heat budget of the tropical South Pacific for the period of January 10-18, 1979 and compares precipitation estimates obtained from the budget equation with those derived from GOES-IR satellite imagery, using data that were part of the total FGGE package. In addition, the relationship between latent heat release and the baroclinic energy conversion is examined for the life cycles of two cyclones which propagated along the South Pacific Convection Zone in that period. It is shown that latent heat plays an important role in the baroclinic energy conversion between potential and kinetic energy through diabatically-induced vertical circulations. For a cyclone where latent heat stays at a high level both spacially and with regard to intensity, there appears to be ample fuel for its intensification. On the other hand, for a filling cyclone, the latent heat impact decreased and the baroclinic conversion fell off rapidly, due to the lack of both potential energy generation and diabatically-induced thermally-direct circulations.

  5. Metal-halide mixtures for latent heat energy storage

    NASA Technical Reports Server (NTRS)

    Chen, K.; Manvi, R.

    1981-01-01

    Some candidates for alkali metal and alkali halide mixtures suitable for thermal energy storage at temperatures 600 C are identified. A solar thermal system application which offer advantages such as precipitation of salt crystals away from heat transfer surfaces, increased thermal conductivity of phase change materials, corrosion inhibition, and a constant monotectic temperature, independent of mixture concentrations. By using the lighters, metal rich phase as a heat transfer medium and the denser, salt rich phase as a phase change material for latent heat storage, undesirable solidification on the heat transfer surface may be prevented, is presented.

  6. The latent heat of vaporization of supercritical fluids

    NASA Astrophysics Data System (ADS)

    Banuti, Daniel; Raju, Muralikrishna; Hickey, Jean-Pierre; Ihme, Matthias

    2016-11-01

    The enthalpy of vaporization is the energy required to overcome intermolecular attractive forces and to expand the fluid volume against the ambient pressure when transforming a liquid into a gas. It diminishes for rising pressure until it vanishes at the critical point. Counterintuitively, we show that a latent heat is in fact also required to heat a supercritical fluid from a liquid to a gaseous state. Unlike its subcritical counterpart, the supercritical pseudoboiling transition is spread over a finite temperature range. Thus, in addition to overcoming intermolecular attractive forces, added energy simultaneously heats the fluid. Then, considering a transition from a liquid to an ideal gas state, we demonstrate that the required enthalpy is invariant to changes in pressure for 0 < p < 3pcr . This means that the classical pressure-dependent latent heat is merely the equilibrium part of the phase transition. The reduction at higher pressures is compensated by an increase in a nonequilibrium latent heat required to overcome residual intermolecular forces in the real fluid vapor during heating. At supercritical pressures, all of the transition occurs at non-equilibrium; for p -> 0 , all of the transition occurs at equilibrium.

  7. Effect of latent heating on mesoscale vortex development during extreme precipitation: Colorado, September 2013

    NASA Astrophysics Data System (ADS)

    Morales, Annareli

    From 9-16 September 2013, a slow-moving cut-off low in the southwestern U.S. funneled unseasonal amounts of moisture to the Colorado Front Range, resulting in extreme precipitation and flooding. The heaviest precipitation during the September 2013 event occurred over the northern Colorado Front Range, producing a 7-day total of over 380 mm of rain. The flash flooding caused over $3 billion in damage to property and infrastructure and resulted in eight fatalities. This study will focus on the precipitation and mesoscale features during 11-12 September 2013 in Boulder, CO. During the evening of 11 September, Boulder experienced flash flooding as a result of high rain rates accumulating over 180 mm of rain in 6 hours. From 0400-0700 UTC 12 September, a mesoscale vortex (mesovortex) was observed to travel northwestward towards Boulder. This circulation enhanced upslope flow and was associated with localized deep convection. The mesovortex originated in an area common for the development of a lee vortex known as the Denver Cyclone. We hypothesize that this mesoscale vortex is not associated with lee vortex formation, such as the Denver Cyclone, but developed through the release of latent heat from microphysical process. The Advanced Research Weather Research and Forecast (ARW) model was used to 1) produce a control simulation that properly represented the evolution and processes of interest during the event and 2) test the importance of latent heating to the development and evolution of the mesovortex. The results from various latent heating experiments suggested that the mesovortex did not develop through lee vortex formation and the latent heat released just before and during the mesovortex event was important to its development. Results also showed latent heating affected the flow field, resulting in a positive feedback between the circulation, associated low-level jet, and convection leading to further upslope flow and precipitation development. Further experiments

  8. The influence of viscous and latent heating on crystal-rich magma flow in a conduit

    NASA Astrophysics Data System (ADS)

    Hale, Alina J.; Wadge, Geoff; Mühlhaus, Hans B.

    2007-12-01

    The flow dynamics of crystal-rich high-viscosity magma is likely to be strongly influenced by viscous and latent heat release. Viscous heating is observed to play an important role in the dynamics of fluids with temperature-dependent viscosities. The growth of microlite crystals and the accompanying release of latent heat should play a similar role in raising fluid temperatures. Earlier models of viscous heating in magmas have shown the potential for unstable (thermal runaway) flow as described by a Gruntfest number, using an Arrhenius temperature dependence for the viscosity, but have not considered crystal growth or latent heating. We present a theoretical model for magma flow in an axisymmetric conduit and consider both heating effects using Finite Element Method techniques. We consider a constant mass flux in a 1-D infinitesimal conduit segment with isothermal and adiabatic boundary conditions and Newtonian and non-Newtonian magma flow properties. We find that the growth of crystals acts to stabilize the flow field and make the magma less likely to experience a thermal runaway. The additional heating influences crystal growth and can counteract supercooling from degassing-induced crystallization and drive the residual melt composition back towards the liquidus temperature. We illustrate the models with results generated using parameters appropriate for the andesite lava dome-forming eruption at Soufrière Hills Volcano, Montserrat. These results emphasize the radial variability of the magma. Both viscous and latent heating effects are shown to be capable of playing a significant role in the eruption dynamics of Soufrière Hills Volcano. Latent heating is a factor in the top two kilometres of the conduit and may be responsible for relatively short-term (days) transients. Viscous heating is less restricted spatially, but because thermal runaway requires periods of hundreds of days to be achieved, the process is likely to be interrupted. Our models show that

  9. Latent heat sink in soil heat flux measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  10. Studies of Phase Change Materials and a Latent Heat Storage Unit Used for a Natural Circulation Cooling/Latent Heat Storage System

    NASA Astrophysics Data System (ADS)

    Sakitani, Katsumi; Honda, Hiroshi

    Experiments were performed to investigate feasibility of using organic materials as a PCM for a latent heat storage unit of a natural circulation cooling/latent heat storage system. This system was designed to cool a shelter accommodating telecommunication equipment located in subtropical deserts or similar regions without using a power source. Taking into account practical considerations and the results of various experiments regarding the thermodynamic properties, thermal degradation, and corrosiveness to metals, lauric acid and iron was selected for the PCM and the latent heat storage unit material, respectively. Cyclic heating and cooling of the latent heat storage unit undergoing solid-liquid phase change was repeated for more than 430 days. The results showed that the heating-cooling curve was almost unchanged between the early stage and the 1,870th cycle. It was concluded that the latent heat storage unit could be used safely for more than ten years as a component of the cooling system.

  11. Shallow and Deep Latent Heating Modes Over Tropical Oceans Observed with TRMM PR Spectral Latent Heating Data

    NASA Technical Reports Server (NTRS)

    Takayabu, Yukari N.; Shige, Shoichi; Tao, Wei-Kuo; Hirota, Nagio

    2010-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. Three-dimensional distributions of latent heating estimated from Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR)utilizing the Spectral Latent Heating (SLH) algorithm are analyzed. Mass-weighted and vertically integrated latent heating averaged over the tropical oceans is estimated as approx.72.6 J/s (approx.2.51 mm/day), and that over tropical land is approx.73.7 J/s (approx.2.55 mm/day), for 30degN-30degS. It is shown that non-drizzle precipitation over tropical and subtropical oceans consists of two dominant modes of rainfall systems, deep systems and congestus. A rough estimate of shallow mode contribution against the total heating is about 46.7 % for the average tropical oceans, which is substantially larger than 23.7 % over tropical land. While cumulus congestus heating linearly correlates with the SST, deep mode is dynamically bounded by large-scale subsidence. It is notable that substantial amount of rain, as large as 2.38 mm day-1 in average, is brought from congestus clouds under the large-scale subsiding circulation. It is also notable that even in the region with SST warmer than 28 oC, large-scale subsidence effectively suppresses the deep convection, remaining the heating by congestus clouds. Our results support that the entrainment of mid-to-lower-tropospheric dry air, which accompanies the large

  12. MJO Signals in Latent Heating: Results from TRMM Retrievals

    NASA Technical Reports Server (NTRS)

    Zhang, Chidong; Ling, Jian; Hagos, Samson; Tao, Wei-Kuo; Lang, Steve; Takayabu, Yukari N.; Shige, Shoichi; Katsumata, Masaki; Olson, William S.; L'Ecuyer, Tristan

    2010-01-01

    The Madden-Julian Oscillation (MJO) is the dominant intraseasonal signal in the global tropical atmosphere. Almost all numerical climate models have difficulty to simulate realistic MJO. Four TRMM datasets of latent heating were diagnosed for signals in the MJO. In all four datasets, vertical structures of latent heating are dominated by two components, one deep with its peak above the melting level and one shallow with its peak below. Profiles of the two components are nearly ubiquitous in longitude, allowing a separation of the vertical and zonal/temporal variations when the latitudinal dependence is not considered. All four datasets exhibit robust MJO spectral signals in the deep component as eastward propagating spectral peaks centered at period of 50 days and zonal wavenumber 1, well distinguished from lower- and higher-frequency power and much stronger than the corresponding westward power. The shallow component shows similar but slightly less robust MJO spectral peaks. MJO signals were further extracted from a combination of band-pass (30 - 90 day) filtered deep and shallow components. Largest amplitudes of both deep and shallow components of the MJO are confined to the Indian and western Pacific Oceans. There is a local minimum in the deep components over the Maritime Continent. The shallow components of the MJO differ substantially among the four TRMM datasets in their detailed zonal distributions in the eastern hemisphere. In composites of the heating evolution through the life cycle of the MJO, the shallow components lead the deep ones in some datasets and at certain longitudes. In many respects, the four TRMM datasets agree well in their deep components, but not in their shallow components and the phase relations between the deep and shallow components. These results indicate that caution must be exercised in applications of these latent heating data.

  13. Sensible and latent heating of the atmosphere as inferred from DST-6 data

    NASA Technical Reports Server (NTRS)

    Herman, G. F.; Schubert, S. D.; Johnson, W. T.

    1979-01-01

    The average distribution of convective latent heating, boundary layer sensible heat flux, and vertical velocity are determined for the winter 1976 DST period from GLAS model diagnostics. Key features are the regions of intense latent heating over Brazil, Central Africa, and Indonesia; and the regions of strong sensible heating due to air mass modification over the North Atlantic and North Pacific Oceans.

  14. Latent heating and cloud processes in warm fronts

    NASA Astrophysics Data System (ADS)

    Igel, Adele

    The results of two studies are presented in this thesis. In the first, an extratropical cyclone that crossed the United States on April 9-11 2009 was successfully simulated at high resolution (3km horizontal grid spacing) using the Colorado State University Regional Atmospheric Modeling System. The sensitivity of the associated warm front to increasing pollution levels was then explored by conducting the same experiment with three different background profiles of cloud-nucleating aerosol concentration. To our knowledge, no study has examined the indirect effects of aerosols on warm fronts. First the budgets of ice, cloud water, and rain in the simulation with the lowest aerosol concentrations were examined. The ice mass was found to be produced in equal amounts through vapor deposition and riming and the melting of ice produced ˜75% of the total rain. Conversion of cloud water to rain accounted for the other 25%. When cloud-nucleating aerosol concentrations were increased, significant changes were seen in the budget terms, but total precipitation was relatively constant. Vapor deposition onto ice increased, but riming of cloud water decreased such that there was only a small change in the total ice production and hence there was no significant change in melting. These responses can be understood in terms of a buffering effect in which smaller cloud droplets in the mixed phase region lead to both an enhanced Bergeron process and decreased riming efficiencies with increasing aerosol concentrations. Overall, while large changes were seen in the microphysical structure of the frontal cloud, cloud-nucleating aerosols had little impact on the precipitation production of the warm front. The second study addresses the role of latent heating associated with the warm front by assessing the relative contributions of individual cloud processes to latent heating and frontogenesis in both the horizontal and vertical directions. Condensation and cloud droplet nucleation are the

  15. Flat plate solar air heater with latent heat storage

    NASA Astrophysics Data System (ADS)

    Touati, B.; Kerroumi, N.; Virgone, J.

    2017-02-01

    Our work contains two parts, first is an experimental study of the solar air heater with a simple flow and forced convection, we can use thatlaste oneit in many engineering's sectors as solardrying, space heating in particular. The second part is a numerical study with ansys fluent 15 of the storage of part of this solar thermal energy produced,using latent heat by using phase change materials (PCM). In the experimental parts, we realize and tested our solar air heater in URER.MS ADRAR, locate in southwest Algeria. Where we measured the solarradiation, ambient temperature, air flow, thetemperature of the absorber, glasses and the outlet temperature of the solar air heater from the Sunrise to the sunset. In the second part, we added a PCM at outlet part of the solar air heater. This PCM store a part of the energy produced in the day to be used in peak period at evening by using the latent heat where the PCMs present a grateful storagesystem.A numerical study of the fusion or also named the charging of the PCM using ANSYS Fluent 15, this code use the method of enthalpies to solve the fusion and solidification formulations. Furthermore, to improve the conjugate heat transfer between the heat transfer fluid (Air heated in solar plate air heater) and the PCM, we simulate the effect of adding fins to our geometry. Also, four user define are write in C code to describe the thermophysicalpropriety of the PCM, and the inlet temperature of our geometry which is the temperature at the outflow of the solar heater.

  16. Environmental Forcing of Super Typhoon Paka's (1997) Latent Heat Structure

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Olson, William; Halverson, Jeff; Simpson, Joanne; Pierce, Harold

    1999-01-01

    The distribution and intensity of total (i.e., combined stratified and convective processes) rainrate/latent heat release (LHR) were derived for tropical cyclone Paka during the period 9-21 December, 1997 from the F-10, F-11, F-13, and F-14 Defense Meteorological Satellite Special Sensor Microwave/Imager and the Tropical Rain Measurement Mission Microwave Imager observations. These observations were frequent enough to capture three episodes of inner core convective bursts that preceded periods of rapid intensification and a convective rainband (CRB) cycle. During these periods of convective bursts, satellite sensors revealed that the rainrates/LHR: 1) increased within the inner eye wall region; 2) were mainly convectively generated (nearly a 65% contribution), 3) propagated inwards; 4) extended upwards within the middle and upper-troposphere, and 5) became electrically charged. These factors may have caused the eye wall region to become more buoyant within the middle and upper-troposphere, creating greater cyclonic angular momentum, and, thereby, warming the center and intensifying the system. Radiosonde measurements from Kwajalein Atoll and Guam, sea surface temperature observations, and the European Center for Medium Range Forecast analyses were used to examine the necessary and sufficient condition for initiating and maintaining these inner core convective bursts. For example, the necessary conditions such as the atmospheric thermodynamics (i.e., cold tropopause temperatures, moist troposphere, and warm SSTs [greater than 26 deg]) suggested that the atmosphere was ideal for Paka's maximum potential intensity (MPI) to approach super-typhoon strength. Further, Paka encountered weak vertical wind shear (less than 15 m/s ) before interacting with the westerlies on 21 December. The sufficient conditions, on the other hand, appeared to have some influence on Paka's convective burst, but the horizontal moisture flux convergence values in the outer core were weaker than

  17. Effect of Latent Heat of Freezing on Crustal Generation at Ultraslow Spreading Rates

    NASA Astrophysics Data System (ADS)

    Sleep, N. H.; Warren, J. M.

    2013-12-01

    The transition between slow and ultraslow ridge axes occurs at the spreading rate below which steady state molten rock cannot exist above the normal Moho depth of ca. 6 km. The latent heat of basaltic magma freezing within the mantle and the kinematics of the seafloor spreading play significant roles in this transition. Using thermal models, we show that freezing of melt at mantle depths buffers temperature due to latent heat of freezing. This allows steady state crustal magma at lower spreading rates than when all the melt freezes at shallow crustal depths. Two quasi-stable seafloor-spreading patterns are possible: (1) basaltic magma along a narrow axial zone, maintaining a hot, weak axial lid that favors this extension pattern; (2) extension in simple shear over a broad zone with isotherms that are horizontal within the cool lid, favoring extension in simple shear. The statistics of basalt, gabbro, melt-impregnated peridotite, and peridotite dredged from transitional ridge axes indicates that the mode of crustal generation is extremely variable at ultraslow spreading rates. Portions of the easternmost Southwest Indian Ridge (SWIR) are spreading at 14 mm per year and consist of 90 percent peridotite, whereas the SWIR Oblique Segment has the same spreading rate but only 37 percent peridotite. Overall, the dredge statistics indicate that some, but not all, the latent heat of ascending magmas is released at mantle depth, that both quasi-stable seafloor-spreading geometries occur, and that magma ascent focuses locally along the strike of transitional ridge axes.

  18. Latent heat storage technology and application workshop. Summary report: Session 6

    NASA Astrophysics Data System (ADS)

    Martin, J. F.

    Latent heat storage technology and application were studied. The economics of short term latent heat storage for application and system configuration were analyzed. Subjects discussed included: state of the art, solar energy stores, residential heating and cooling, and industrial and utility applications.

  19. Wallboard with Latent Heat Storage for Passive Solar Applications

    SciTech Connect

    Kedl, R.J.

    2001-05-31

    Conventional wallboard impregnated with octadecane paraffin [melting point-23 C (73.5 F)] is being developed as a building material with latent heat storage for passive solar and other applications. Impregnation was accomplished simply by soaking the wallboard in molten wax. Concentrations of wax in the combined product as high as 35% by weight can be achieved. Scale-up of the soaking process, from small laboratory samples to full-sized 4- by 8-ft sheets, has been successfully accomplished. The required construction properties of wallboard are maintained after impregnation, that is, it can be painted and spackled. Long-term, high-temperature exposure tests and thermal cycling tests showed no tendency of the paraffin to migrate within the wallboard, and there was no deterioration of thermal energy storage capacity. In support of this concept, a computer model was developed to handle thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions and also by comparison with temperatures measured in wallboard during an experimentally generated thermal transient. Agreement between the model and known solution was excellent. Agreement between the model and thermal transient was good, only after the model was modified to allow the PCM to melt over a temperature range, rather than at a specific melting point. When the melting characteristics of the PCM (melting point, melting range, and heat of fusion), as determined from a differential scanning calorimeter plot, were used in the model, agreement between the model and transient data was very good. The confirmed computer model may now be used in conjunction with a building heating and cooling code to evaluate design parameters and operational characteristics of latent heat storage wallboard for passive solar applications.

  20. Including latent and sensible heat fluxes from sea spray in global weather and climate models

    NASA Astrophysics Data System (ADS)

    Copsey, Dan

    2016-04-01

    Most standard weather and climate models calculate interfacial latent (evaporation) and sensible heat fluxes over the ocean based on parameterisations of atmospheric turbulence, using the wave state only in the calculation of surface roughness length. They ignore latent and sensible heat fluxes generated by sea spray, which is an acceptable assumption at low wind speeds. However at high wind speeds (> 15 m/s) a significant amount of sea spray is generated from the sea surface which, while airborne, cools to an equilibrium temperature, absorbs heat and releases moisture before re-impacting the sea surface. This could impact, for example, the total heat loss from the Southern Ocean (which is anomalously warm in Met Office coupled models) or the accuracy of tropical cyclone forecasts. A modified version of the Fairall sea spray parameterisation scheme has been tested in the Met Office Unified Model including the JULES surface exchange model in both climate and NWP mode. The fast part of the scheme models the temperature change of the droplets to an equilibrium temperature and the slow part of the scheme models the evaporation and heat absorption while the droplets remain airborne. Including this scheme in the model cools and moistens the near surface layers of the atmosphere during high wind events, including tropical cyclones. Sea spray goes on to increase the convection intensity and precipitation near the high wind events in the model.

  1. Relating Convective and Stratiform Rain to Latent Heating

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, Stephen; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

    2010-01-01

    The relationship among surface rainfall, its intensity, and its associated stratiform amount is established by examining observed precipitation data from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). The results show that for moderate-high stratiform fractions, rain probabilities are strongly skewed toward light rain intensities. For convective-type rain, the peak probability of occurrence shifts to higher intensities but is still significantly skewed toward weaker rain rates. The main differences between the distributions for oceanic and continental rain are for heavily convective rain. The peak occurrence, as well as the tail of the distribution containing the extreme events, is shifted to higher intensities for continental rain. For rainy areas sampled at 0.58 horizontal resolution, the occurrence of conditional rain rates over 100 mm/day is significantly higher over land. Distributions of rain intensity versus stratiform fraction for simulated precipitation data obtained from cloud-resolving model (CRM) simulations are quite similar to those from the satellite, providing a basis for mapping simulated cloud quantities to the satellite observations. An improved convective-stratiform heating (CSH) algorithm is developed based on two sources of information: gridded rainfall quantities (i.e., the conditional intensity and the stratiform fraction) observed from the TRMM PR and synthetic cloud process data (i.e., latent heating, eddy heat flux convergence, and radiative heating/cooling) obtained from CRM simulations of convective cloud systems. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. Major differences between the new and old algorithms include a significant increase in the amount of low- and midlevel heating, a downward emphasis in the level of maximum cloud heating by about 1 km, and a larger variance between land and ocean in

  2. Method of testing active latent-heat storage devices based on thermal performance. (ASHRAE standard)

    SciTech Connect

    1985-01-26

    The purpose of this standard is to provide a standard procedure for determining the thermal performance of latent heat thermal energy storage devices used in heating, air-conditioning, and service hot water systems.

  3. Impact of Ridge Induced Latent Heat Advection on Sea Ice Global Heat Budget.

    NASA Astrophysics Data System (ADS)

    Hudier, E.; Gosselin, J.

    2008-12-01

    The effects of permeability on ice keel induced latent heat fluxes are examined using pressure ridge density statistics computed from SAR images and a prognostic simulation of forced brine advection through the bottom ice layer. Under pressure gradients generated in the wake of an ice keel sea water is pushed into and brine pumped out of the bottom ice layer. This in turn causes a new thermodynamic equilibrium to be reached. At spring when the ice permeability increases, brine export combined with sea water import translates into an advective heat flow that is balanced by the latent heat absorbed by volume melting of brine channel walls. Sea ice within the sheltered areas behind keels is modelled as an anisotropic heteregeneous mushy layer. The non-linear equation system within each cell is implemented on a finite volume grid and include volume melt of the brine channels from which porosity, water density, temperature and salinity are computed. Outputs from these simulations are then combined with ridge distribution statistics to evaluate the global impact of latent heat absorbed due to volume melting in the wake of ridges. As anticipated, results are highly dependent on permeability, nevertheless, they show that pressure ridge induced melting within the ice is a significant component of the heat budget when compared with melting at the ice water interface. This work underlines needs for further researches to improve our understanding of ice permeability changes during the melt season, it also calls for better tools to extract pressure ridge characteristics from satellite images.

  4. Experimental Investigation of A Heat Pipe-Assisted Latent Heat Thermal Energy Storage System

    NASA Astrophysics Data System (ADS)

    Tiari, Saeed; Mahdavi, Mahboobe; Qiu, Songgang

    2016-11-01

    In the present work, different operation modes of a latent heat thermal energy storage system assisted by a heat pipe network were studied experimentally. Rubitherm RT55 enclosed by a vertical cylindrical container was used as the Phase Change Material (PCM). The embedded heat pipe network consisting of a primary heat pipe and an array of four secondary heat pipes were employed to transfer heat to the PCM. The primary heat pipe transports heat from the heat source to the heat sink. The secondary heat pipes transfer the extra heat from the heat source to PCM during charging process or retrieve thermal energy from PCM during discharging process. The effects of heat transfer fluid (HTF) flow rate and temperature on the thermal performance of the system were investigated for both charging and discharging processes. It was found that the HTF flow rate has a significant effect on the total charging time of the system. Increasing the HTF flow rate results in a remarkable increase in the system input thermal power. The results also showed that the discharging process is hardly affected by the HTF flow rate but HTF temperature plays an important role in both charging and discharging processes. The authors would like to acknowledge the financial supports by Temple University for the project.

  5. The microphysical contributions to and evolution of latent heating profiles in two MC3E MCSs

    NASA Astrophysics Data System (ADS)

    Marinescu, P. J.; Heever, S. C.; Saleeby, S. M.; Kreidenweis, S. M.

    2016-07-01

    The shapes and magnitudes of latent heating profiles have been shown to be different within the convective and stratiform regions of mesoscale convective systems (MCSs). Properly representing these distinctions has significant implications for the atmospheric responses to latent heating on various scales. This study details (1) the microphysical process contributions to latent heating profiles within MCS convective, stratiform, and anvil regions and (2) the time evolution of these profiles throughout the MCS lifetime, using cloud-resolving model simulations. Simulations of two MCS events that occurred during the Midlatitude Continental Convective Clouds Experiment (MC3E) are conducted. Several features of the simulated MCSs are compared to a suite of observations obtained during the MC3E field campaign, and it is concluded that the simulations reasonably reproduce the MCS events. The simulations show that condensation and deposition are the primary contributors to MCS latent warming, as compared to riming and nucleation processes. In terms of MCS latent cooling, sublimation, melting, and evaporation all play significant roles. It is evident that throughout the MCS lifecycle, convective regions demonstrate an approximately linear decrease in the magnitudes of latent heating rates, while latent heating within stratiform regions is associated with transitions between MCS flow regimes. Such information regarding the temporal evolution of latent heating within convective and stratiform MCS regions could be useful in developing parameterizations representing convective organization.

  6. Sensible and latent heat flux estimates in Antarctica

    NASA Technical Reports Server (NTRS)

    Stearns, Charles R.; Weidner, George A.

    1993-01-01

    The assumption has been made that the net annual contribution of water by the processes of deposition and sublimation to the Antarctic Ice Sheet is zero. The U.S. Antarctic Program started installing reliable automatic weather stations on the Antarctic Continent in 1980. The initial units were equipped to measure wind speed, wind direction, air pressure, and air temperature. During the 1983-1984 field season in Antarctica, three units were installed that measured a vertical air temperature difference between the nominal heights of 0.5 m and 3.0 m and relative humidity at a nominal height of 3 m. The measurements of the vertical air temperature difference and the relative humidity are the minimum required to estimate the sensible and latent heat fluxes to the air, while not exceeding the available energy requirements for the weather stations. The estimates of the net annual sublimation and deposition on the Ross Ice Shelf amount to 20 to 80 percent of the annual accumulation. We conclude that the assumption that annual sublimation and deposition are zero is not valid under Antarctic conditions.

  7. Preparation of fine powdered composite for latent heat storage

    NASA Astrophysics Data System (ADS)

    Fořt, Jan; Pomaleski, Marina; Trník, Anton; Pavlíková, Milena; Pavlík, Zbyšek

    2016-07-01

    Application of latent heat storage building envelope systems using phase-change materials represents an attractive method of storing thermal energy and has the advantages of high-energy storage density and the isothermal nature of the storage process. This study deals with a preparation of a new type of powdered phase change composite material for thermal energy storage. The idea of a composite is based upon the impregnation of a natural silicate material by a reasonably priced commercially produced pure phase change material and forming the homogenous composite powdered structure. For the preparation of the composite, vacuum impregnation method is used. The particle size distribution accessed by the laser diffraction apparatus proves that incorporation of the organic phase change material into the structure of inorganic siliceous pozzolana does not lead to the clustering of the particles. The compatibility of the prepared composite is characterized by the Fourier transformation infrared analysis (FTIR). Performed DSC analysis shows potential of the developed composite for thermal energy storage that can be easily incorporated into the cement-based matrix of building materials. Based on the obtained results, application of the developed phase change composite can be considered with a great promise.

  8. A Retrieval of Tropical Latent Heating Using the 3D Structure of Precipitation Features

    SciTech Connect

    Ahmed, Fiaz; Schumacher, Courtney; Feng, Zhe; Hagos, Samson

    2016-09-01

    Traditionally, radar-based latent heating retrievals use rainfall to estimate the total column-integrated latent heating and then distribute that heating in the vertical using a model-based look-up table (LUT). In this study, we develop a new method that uses size characteristics of radar-observed precipitating echo (i.e., area and mean echo-top height) to estimate the vertical structure of latent heating. This technique (named the Convective-Stratiform Area [CSA] algorithm) builds on the fact that the shape and magnitude of latent heating profiles are dependent on the organization of convective systems and aims to avoid some of the pitfalls involved in retrieving accurate rainfall amounts and microphysical information from radars and models. The CSA LUTs are based on a high-resolution Weather Research and Forecasting model (WRF) simulation whose domain spans much of the near-equatorial Indian Ocean. When applied to S-PolKa radar observations collected during the DYNAMO/CINDY2011/AMIE field campaign, the CSA retrieval compares well to heating profiles from a sounding-based budget analysis and improves upon a simple rain-based latent heating retrieval. The CSA LUTs also highlight the fact that convective latent heating increases in magnitude and height as cluster area and echo-top heights grow, with a notable congestus signature of cooling at mid levels. Stratiform latent heating is less dependent on echo-top height, but is strongly linked to area. Unrealistic latent heating profiles in the stratiform LUT, viz., a low-level heating spike, an elevated melting layer, and net column cooling were identified and corrected for. These issues highlight the need for improvement in model parameterizations, particularly in linking microphysical phase changes to larger mesoscale processes.

  9. The role of latent heat in kinetic energy conversions of South Pacific cyclones

    NASA Technical Reports Server (NTRS)

    Kann, Deirdre M.; Vincent, Dayton G.

    1986-01-01

    The four-dimensional behavior of cyclone systems in the South Pacific Convergence Zone (SPCZ) is analyzed. Three cyclone systems, which occurred during the period from January 10-16, 1979, are examined using the data collected during the first special observing period of the FGGE. The effects of latent heating on the life cycles of the cyclones are investigated. Particular attention is given to the conversions of eddy available potential energy to eddy kinetic energy and of mean kinetic energy to eddy kinetic energy. The net radiation profile, sensible heat flux, total field of vertical motion, and latent heat component were computed. The life cycles of the cyclones are described. It is observed that the latent heating component accounts for nearly all the conversion in the three cyclones, and latent heating within the SPCZ is the major source of eddy kinetic energy for the cyclones.

  10. High temperature latent heat thermal energy storage to augment solar thermal propulsion for microsatellites

    NASA Astrophysics Data System (ADS)

    Gilpin, Matthew R.

    technology for the platform. The use of silicon and boron as high temperature latent heat thermal energy storage materials has been in the background of solar thermal research for decades without a substantial investigation. This is despite a broad agreement in the literature about the performance benefits obtainable from a latent heat mechanisms which provides a high energy storage density and quasi-isothermal heat release at high temperature. In this work, an experimental approach was taken to uncover the practical concerns associated specifically with applying silicon as an energy storage material. A new solar furnace was built and characterized enabling the creation of molten silicon in the laboratory. These tests have demonstrated the basic feasibility of a molten silicon based thermal energy storage system and have highlighted asymmetric heat transfer as well as silicon expansion damage to be the primary engineering concerns for the technology. For cylindrical geometries, it has been shown that reduced fill factors can prevent damage to graphite walled silicon containers at the expense of decreased energy storage density. Concurrent with experimental testing, a cooling model was written using the "enthalpy method" to calculate the phase change process and predict test section performance. Despite a simplistic phase change model, and experimentally demonstrated complexities of the freezing process, results coincided with experimental data. It is thus possible to capture essential system behaviors of a latent heat thermal energy storage system even with low fidelity freezing kinetics modeling allowing the use of standard tools to obtain reasonable results. Finally, a technological road map is provided listing extant technological concerns and potential solutions. Improvements in container design and an increased understanding of convective coupling efficiency will ultimately enable both high temperature latent heat thermal energy storage and a new class of high

  11. Heat Transfer and Latent Heat Storage in Inorganic Molten Salts for Concentrating Solar Power Plants

    SciTech Connect

    Mathur, Anoop

    2013-08-14

    A key technological issue facing the success of future Concentrating Solar Thermal Power (CSP) plants is creating an economical Thermal Energy Storage (TES) system. Current TES systems use either sensible heat in fluids such as oil, or molten salts, or use thermal stratification in a dual-media consisting of a solid and a heat-transfer fluid. However, utilizing the heat of fusion in inorganic molten salt mixtures in addition to sensible heat , as in a Phase change material (PCM)-based TES, can significantly increase the energy density of storage requiring less salt and smaller containers. A major issue that is preventing the commercial use of PCM-based TES is that it is difficult to discharge the latent heat stored in the PCM melt. This is because when heat is extracted, the melt solidifies onto the heat exchanger surface decreasing the heat transfer. Even a few millimeters of thickness of solid material on heat transfer surface results in a large drop in heat transfer due to the low thermal conductivity of solid PCM. Thus, to maintain the desired heat rate, the heat exchange area must be large which increases cost. This project demonstrated that the heat transfer coefficient can be increase ten-fold by using forced convection by pumping a hyper-eutectic salt mixture over specially coated heat exchanger tubes. However,only 15% of the latent heat is used against a goal of 40% resulting in a projected cost savings of only 17% against a goal of 30%. Based on the failure mode effect analysis and experience with pumping salt at near freezing point significant care must be used during operation which can increase the operating costs. Therefore, we conclude the savings are marginal to justify using this concept for PCM-TES over a two-tank TES. The report documents the specialty coatings, the composition and morphology of hypereutectic salt mixtures and the results from the experiment conducted with the active heat exchanger along with the lessons learnt during

  12. TRMM Latent Heating Retrieval and Comparisons with Field Campaigns and Large-Scale Analyses

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Takayabu, Yukuri; Lang, S.; Shige, S.; Olson, W.; Hou, A.; Jiang, X.; Zhang, C.; Lau, W.; Krishnamurti, T.; Waliser, D.; Grecu, M.; Ciesielski, P. E.; Johnson, R. H.; Houze, R.; Kakar, R.; Nakamura, K.; Braun, S.; Hagos, S.; Oki, R.; Bhardwaj, A.

    2012-01-01

    Rainfall production is a fundamental process within the Earth's hydrological cycle because it represents both a principal forcing term in surface water budgets, and its energetics corollary, latent heating (LH), is one of the principal sources of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The vertical distribution of LH has a strong influence on the atmosphere, controlling large-scale tropical circulations, exciting and modulating tropical waves, maintaining the intensities of tropical cyclones, and even providing the energetics of midlatitude cyclones and other mobile midlatitude weather systems. Moreover, the processes associated with LH result in significant non-linear changes in atmospheric radiation through the creation, dissipation and modulation of clouds and precipitation. Yanai et al. (1973) utilized the meteorological data collected from a sounding network to present a pioneering work on thermodynamic budgets, which are referred to as the apparent heat source (Q1) and apparent moisture sink (Q2). Yanai's paper motivated the development of satellite-based LH algorithms and provided a theoretical background for imposing large-scale advective forcing into cloud-resolving models (CRMs). These CRM-simulated LH and Q1 data have been used to generate the look-up tables used in LH algorithms. This paper examines the retrieval, validation, and application of LH estimates based on rain rate quantities acquired from the Tropical Rainfall Measuring Mission satellite (TRMM). TRMM was launched in November 1997 as a joint enterprise between the American and Japanese space agencies -- with overriding goals of providing accurate four-dimensional estimates of rainfall and LH over the global Tropics and subtropics equatorward of 35o. Other literature has acknowledged the achievement of the first goal of obtaining an accurate rainfall climatology. This paper describes the

  13. Latent heat exchange in the boreal and arctic biomes.

    PubMed

    Kasurinen, Ville; Alfredsen, Knut; Kolari, Pasi; Mammarella, Ivan; Alekseychik, Pavel; Rinne, Janne; Vesala, Timo; Bernier, Pierre; Boike, Julia; Langer, Moritz; Belelli Marchesini, Luca; van Huissteden, Ko; Dolman, Han; Sachs, Torsten; Ohta, Takeshi; Varlagin, Andrej; Rocha, Adrian; Arain, Altaf; Oechel, Walter; Lund, Magnus; Grelle, Achim; Lindroth, Anders; Black, Andy; Aurela, Mika; Laurila, Tuomas; Lohila, Annalea; Berninger, Frank

    2014-11-01

    In this study latent heat flux (λE) measurements made at 65 boreal and arctic eddy-covariance (EC) sites were analyses by using the Penman-Monteith equation. Sites were stratified into nine different ecosystem types: harvested and burnt forest areas, pine forests, spruce or fir forests, Douglas-fir forests, broadleaf deciduous forests, larch forests, wetlands, tundra and natural grasslands. The Penman-Monteith equation was calibrated with variable surface resistances against half-hourly eddy-covariance data and clear differences between ecosystem types were observed. Based on the modeled behavior of surface and aerodynamic resistances, surface resistance tightly control λE in most mature forests, while it had less importance in ecosystems having shorter vegetation like young or recently harvested forests, grasslands, wetlands and tundra. The parameters of the Penman-Monteith equation were clearly different for winter and summer conditions, indicating that phenological effects on surface resistance are important. We also compared the simulated λE of different ecosystem types under meteorological conditions at one site. Values of λE varied between 15% and 38% of the net radiation in the simulations with mean ecosystem parameters. In general, the simulations suggest that λE is higher from forested ecosystems than from grasslands, wetlands or tundra-type ecosystems. Forests showed usually a tighter stomatal control of λE as indicated by a pronounced sensitivity of surface resistance to atmospheric vapor pressure deficit. Nevertheless, the surface resistance of forests was lower than for open vegetation types including wetlands. Tundra and wetlands had higher surface resistances, which were less sensitive to vapor pressure deficits. The results indicate that the variation in surface resistance within and between different vegetation types might play a significant role in energy exchange between terrestrial ecosystems and atmosphere. These results suggest the need

  14. Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

    NASA Astrophysics Data System (ADS)

    Hawcroft, Matt; Dacre, Helen; Forbes, Richard; Hodges, Kevin; Shaffrey, Len; Stein, Thorwald

    2016-06-01

    Extratropical cyclones are a key feature of the weather in the extratropics, which climate models need to represent in order to provide reliable projections of future climate. Extratropical cyclones produce significant precipitation and the associated latent heat release can play a major role in their development. This study evaluates the ability of a climate model, HiGEM, to represent latent heating in extratropical cyclones. Remote sensing data is used to investigate the ability of both the climate model and ERA-Interim (ERAI) reanalysis to represent extratropical cyclone cloud features before latent heating itself is assessed. An offline radiance simulator, COSP, and the ISCCP and CloudSat datasets are used to evaluate comparable fields from HiGEM and ERAI. HiGEM is found to exhibit biases in the cloud structure of extratropical cyclones, with too much high cloud produced in the warm conveyor belt region compared to ISCCP. Significant latent heating occurs in this region, derived primarily from HiGEM's convection scheme. ERAI is also found to exhibit biases in cloud structure, with more clouds at lower altitudes than those observed in ISCCP in the warm conveyor belt region. As a result, latent heat release in ERAI is concentrated at lower altitudes. CloudSat indicates that much precipitation may be produced at too low an altitude in both HiGEM and ERAI, particularly ERAI, and neither capture observed variability in precipitation intensity. The potential vorticity structure in composite extratropical cyclones in HiGEM and ERAI is also compared. A more pronounced tropopause ridge evolves in HiGEM on the leading edge of the composite as compared to ERAI. One future area of research to be addressed is what impact these biases in the representation of latent heating have on climate projections produced by HiGEM. The biases found in ERAI indicate caution is required when using reanalyses to study cloud features and precipitation processes in extratropical cyclones or

  15. Measurement of Latent Heat of Melting of Thermal Storage Materials for Dynamic Type Ice Thermal Storage

    NASA Astrophysics Data System (ADS)

    Sawada, Hisashi; Okada, Masashi; Nakagawa, Shinji

    In order to measure the latent heat of melting of ice slurries with various solute concentrations, an adiabatic calorimeter was constructed. Ice slurries were made from each aqueous solution of ethanol, ethylene glycol and silane coupling agent. The latent heat of melting of ice made from tap water was measured with the present calorimeter and the uncertainty of the result was one percent. Ice slurries were made both by mixing ice particles made from water with each aqueous solution and by freezing each aqueous solution with stirring in a vessel. The latent heat of melting of these ice slurries was measured with various concentrations of solution. The latent heat of melting decreased as the solute concentration or the freezing point depression increased. The latent heat of ice slurries made from ethanol or ethylene glycol aqueous solution agreed with that of ice made from pure water known already. The latent heat of melting of ice slurries made from silane coupling agent aqueous solution got smaller than that of ice made from pure water as the freezing point depression increased.

  16. Active heat exchange: System development for latent heat thermal energy storage

    NASA Astrophysics Data System (ADS)

    Alario, J.; Haslett, R.

    1981-03-01

    An active heat exchange method in a latent heat (salt) thermal energy storage system that prevents a low conductivity solid salt layer from forming on heat transfer surfaces was developed. An evaluation of suitable media with melting points in the temperature range of interest (250 to 400 C) limited the candidates to molten salts from the chloride, hydroxide, and nitrate families, based on high storage capacity, good corrosion characteristics, and availability in large quantities at reasonable cost. The specific salt recommended for laboratory tests was a choride eutectic (20.5KCl, 24.5NaCl, 55.0MgCl2 percent by wt.), with a nominal melting point of 385 C.

  17. Thermodynamics of latent heat storage in parallel or in series with a heat engine

    NASA Astrophysics Data System (ADS)

    Charach, Chaim; Conti, Massimo

    1995-08-01

    The thermodynamics of a latent heat storage element, connected to a heat source, periodically varying in time, and to a heat engine, is addressed. Two typical modes of operation, referred to as the series and the parallel setups, are considered. They differ with regard to the active phase of the heat source. For the series mode the entire amount of heat transfer fluid (HTF), coming from the source, is first passed through the thermal storage element (TSE) before entering the engine. For the parallel setup only a fraction of the HTF, supplied by the heat source, is delivered directly to the engine, whereas the remaining fraction of HTF is pumped into the TSE to facilitate the exergy storage. The optimal selection of the freezing point of the phase-change material (PCM), the stability of operation of the engine, and the entropy production in the TSE during the heat storage-discharge cycle are considered. The parallel and the series modes of operation are compared for some simplified TSE models. For these models the series setup yields a higher efficiency and stability than the parallel scheme.

  18. Latent Heating Retrievals Using the TRMM Precipitation Radar: A Multi-Seasonal Study

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Meneghini, B.; Halverson, J.; Johnson, R.; Simpson, J.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The Goddard Convective-Stratiform Heating (CSH) algorithm is used to retrieve profiles of latent heating over the global tropics for a period of several months using TRMM precipitation radar data. The seasonal variation of heating over the tropics is then examined. The period of interest also coincides with several TRMM field campaigns that recently occurred over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and in the central Pacific in 1999 (KWAJEX). Sounding diagnosed Q1 budgets from these experiments could provide a means of validating the retrieved profiles of latent heating from the CSH algorithm.

  19. Modeling conductive heat transfer during high-pressure thawing processes: determination of latent heat as a function of pressure.

    PubMed

    Denys, S; Van Loey, A M; Hendrickx, M E

    2000-01-01

    A numerical heat transfer model for predicting product temperature profiles during high-pressure thawing processes was recently proposed by the authors. In the present work, the predictive capacity of the model was considerably improved by taking into account the pressure dependence of the latent heat of the product that was used (Tylose). The effect of pressure on the latent heat of Tylose was experimentally determined by a series of freezing experiments conducted at different pressure levels. By combining a numerical heat transfer model for freezing processes with a least sum of squares optimization procedure, the corresponding latent heat at each pressure level was estimated, and the obtained pressure relation was incorporated in the original high-pressure thawing model. Excellent agreement with the experimental temperature profiles for both high-pressure freezing and thawing was observed.

  20. Active latent heat storage with a screw heat exchanger - experimental results for heat transfer and concept for high pressure steam

    NASA Astrophysics Data System (ADS)

    Zipf, Verena; Willert, Daniel; Neuhäuser, Anton

    2016-05-01

    An innovative active latent heat storage concept was invented and developed at Fraunhofer ISE. It uses a screw heat exchanger (SHE) for the phase change during the transport of a phase change material (PCM) from a cold to a hot tank or vice versa. This separates heat transfer and storage tank in comparison to existing concepts. A test rig has been built in order to investigate the heat transfer coefficients of the SHE during melting and crystallization of the PCM. The knowledge of these characteristics is crucial in order to assess the performance of the latent heat storage in a thermal system. The test rig contains a double shafted SHE, which is heated or cooled with thermal oil. The overall heat transfer coefficient U and the convective heat transfer coefficient on the PCM side hPCM both for charging and discharging have been calculated based on the measured data. For charging, the overall heat transfer coefficient in the tested SHE was Uch = 308 W/m2K and for discharging Udis = 210 W/m2K. Based on the values for hPCM the overall heat transfer coefficients for a larger SHE with steam as heat transfer fluid and an optimized geometry were calculated with Uch = 320 W/m2K for charging and Udis = 243 W/m2K for discharging. For pressures as high as p = 100 bar, an SHE concept has been developed, which uses an organic fluid inside the flight of the SHE as working media. With this concept, the SHE can also be deployed for very high pressure, e.g. as storage in solar thermal power plants.

  1. Apparent latent heat of evaporation from clothing: attenuation and "heat pipe" effects.

    PubMed

    Havenith, George; Richards, Mark G; Wang, Xiaoxin; Bröde, Peter; Candas, Victor; den Hartog, Emiel; Holmér, Ingvar; Kuklane, Kalev; Meinander, Harriet; Nocker, Wolfgang

    2008-01-01

    Investigating claims that a clothed person's mass loss does not always represent their evaporative heat loss (EVAP), a thermal manikin study was performed measuring heat balance components in more detail than human studies would permit. Using clothing with different levels of vapor permeability and measuring heat losses from skin controlled at 34 degrees C in ambient temperatures of 10, 20, and 34 degrees C with constant vapor pressure (1 kPa), additional heat losses from wet skin compared with dry skin were analyzed. EVAP based on mass loss (E(mass)) measurement and direct measurement of the extra heat loss by the manikin due to wet skin (E(app)) were compared. A clear discrepancy was observed. E(mass) overestimated E(app) in warm environments, and both under and overestimations were observed in cool environments, depending on the clothing vapor permeability. At 34 degrees C, apparent latent heat (lambda(app)) of pure evaporative cooling was lower than the physical value (lambda; 2,430 J/g) and reduced with increasing vapor resistance up to 45%. At lower temperatures, lambda(app) increases due to additional skin heat loss via evaporation of moisture that condenses inside the clothing, analogous to a heat pipe. For impermeable clothing, lambda(app) even exceeds lambda by four times that value at 10 degrees C. These findings demonstrate that the traditional way of calculating evaporative heat loss of a clothed person can lead to substantial errors, especially for clothing with low permeability, which can be positive or negative, depending on the climate and clothing type. The model presented explains human subject data on EVAP that previously seemed contradictive.

  2. [Dynamics of sensible and latent heat fluxes over a temperate desert steppe ecosystem in Inner Mongolia].

    PubMed

    Zhang, Guo; Zhou, Guang-Sheng; Yang, Fu-Lin

    2010-03-01

    This paper studied the diurnal and seasonal characteristics of sensible and latent heat fluxes over a temperate desert steppe ecosystem in Inner Mongolia, based on the 2008 observation data from eddy covariance tower. The diurnal patterns of sensible and latent heat fluxes over the ecosystem were both single kurtosis, with the maximum value being 319.01 W x m(-2) (on May 30th, 2008) and 425.37 W x m(-2) (on Jun 2nd, 2008), respectively, and occurred at about 12:00-13:30 (local time), which was similar to the diurnal pattern of net radiation but lagged about one hour of the maximum net radiation. The maximum diurnal variations of monthly mean sensible and latent heat fluxes occurred in May and June, and their minimum diurnal variations occurred in January and November, respectively. There was a closer relationship between soil moisture content and precipitation. Surface soil moisture content was most sensitive to precipitation, while the moisture content in deeper soil layers had a lagged response to precipitation. The seasonal dynamics of sensible and latent heat fluxes was similar to that of net radiation, and affected by precipitation. Sensible heat flux was obviously affected by net radiation, but latent heat flux was more sensitive to precipitation and mainly controlled by soil moisture content.

  3. Latent heat in uniaxially stressed KMnF3 ferroelastic crystal

    NASA Astrophysics Data System (ADS)

    Romero, F. J.; Gallardo, M. C.; Jimenez, J.; del Cerro, J.; Salje, E. K. H.

    2000-05-01

    The influence of weak uniaxial stress on both the latent heat and the coexistence interval of the ferroelastic phase transition of KMnF3 has been measured using a sensitive conduction calorimeter. The latent heat of the sample without stress is 0.129 J g-1 and, in the range of \\mbox{0-12} bar, it increases weakly with the stress. The width of the interval where the latent heat appears increases with stress, with an apparently larger coexistence interval. Heating and cooling processes show different kinetic behaviours. On cooling, the maximum of the differential thermal analysis traces splits into two peaks when a uniaxial stress is applied, which is related to the formation of ferroelastic domain patterns.

  4. Numerical study of finned heat pipe-assisted latent heat thermal energy storage system

    NASA Astrophysics Data System (ADS)

    Tiari, Saeed; Qiu, Songgang; Mahdavi, Mahboobe

    2014-11-01

    In the present study the thermal characteristics of a finned heat pipe-assisted latent heat thermal energy storage system are investigated numerically. A transient two dimensional finite volume based model employing enthalpy-porosity technique is implemented to analyze the performance of a thermal energy storage unit with square container and high melting temperature phase change material. The effects of heat pipe spacing, fin length and numbers as well as the influence of natural convection on the thermal response of the thermal energy storage unit have been studied. The obtained results reveal that the natural convection has considerable effect on the melting process of the phase change material. Increasing the number of heat pipes leads to the increase of melting rate and the decrease of base wall temperature. Also, the increase of fin length results in the decrease of temperature difference within the phase change material in the container, providing more uniform temperature distribution. Furthermore, it is showed that the number of fins does not affect the performance of the system considerably.

  5. Experimental investigation of the latent heat of vaporization in aqueous nanofluids

    SciTech Connect

    Lee, Soochan; Phelan, Patrick E. Dai, Lenore; Prasher, Ravi; Gunawan, Andrey; Taylor, Robert A.

    2014-04-14

    This paper reports an experimental investigation of the latent heat of vaporization (h{sub fg}) in nanofluids. Two different types of nanoparticles, graphite and silver, suspended in deionized water were exposed to a continuous laser beam (130 mW, 532 nm) to generate boiling. The latent heat of vaporization in the nanofluids was determined by the measured vapor mass generation and the heat input. To ensure that the measured h{sub fg} values are independent of heating method, the experiments were repeated with an electrically heated hot wire as a primary heat input. These experiments show considerable variation in the h{sub fg} of nanofluids. That is, graphite nanofluid exhibits an increased h{sub fg} and silver nanofluid shows a decrease in h{sub fg} compared to the value for pure water. As such, these results indicate that relatively low mass fractions of nanoparticles can apparently create large changes in h{sub fg}.

  6. Experimental investigation of the latent heat of vaporization in aqueous nanofluids

    NASA Astrophysics Data System (ADS)

    Lee, Soochan; Phelan, Patrick E.; Dai, Lenore; Prasher, Ravi; Gunawan, Andrey; Taylor, Robert A.

    2014-04-01

    This paper reports an experimental investigation of the latent heat of vaporization (hfg) in nanofluids. Two different types of nanoparticles, graphite and silver, suspended in deionized water were exposed to a continuous laser beam (130 mW, 532 nm) to generate boiling. The latent heat of vaporization in the nanofluids was determined by the measured vapor mass generation and the heat input. To ensure that the measured hfg values are independent of heating method, the experiments were repeated with an electrically heated hot wire as a primary heat input. These experiments show considerable variation in the hfg of nanofluids. That is, graphite nanofluid exhibits an increased hfg and silver nanofluid shows a decrease in hfg compared to the value for pure water. As such, these results indicate that relatively low mass fractions of nanoparticles can apparently create large changes in hfg.

  7. Passive ice freezing-releasing heat pipe

    DOEpatents

    Gorski, Anthony J.; Schertz, William W.

    1982-01-01

    A heat pipe device has been developed which permits completely passive ice formation and periodic release of ice without requiring the ambient temperature to rise above the melting point of water. This passive design enables the maximum amount of cooling capacity to be stored in the tank.

  8. Simulation and evaluation of latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Sigmon, T. W.

    1980-01-01

    The relative value of thermal energy storage (TES) for heat pump storage (heating and cooling) as a function of storage temperature, mode of storage (hotside or coldside), geographic locations, and utility time of use rate structures were derived. Computer models used to simulate the performance of a number of TES/heat pump configurations are described. The models are based on existing performance data of heat pump components, available building thermal load computational procedures, and generalized TES subsystem design. Life cycle costs computed for each site, configuration, and rate structure are discussed.

  9. Interferon Gamma Release Assays for Latent Tuberculosis: What Are the Sources of Variability?

    PubMed Central

    Gaur, Rajiv L.; Pai, Madhukar

    2016-01-01

    Interferon gamma release assays (IGRAs) are blood-based tests intended for diagnosis of latent tuberculosis infection (LTBI). IGRAs offer logistical advantages and are supposed to offer improved specificity over the tuberculin skin test (TST). However, recent serial testing studies of low-risk individuals have revealed higher false conversion rates with IGRAs than with TST. Reproducibility studies have identified various sources of variability that contribute to nonreproducible results. Sources of variability can be broadly classified as preanalytical, analytical, postanalytical, manufacturing, and immunological. In this minireview, we summarize known sources of variability and their impact on IGRA results. We also provide recommendations on how to minimize sources of IGRA variability. PMID:26763969

  10. Latent heating and mixing due to entrainment in tropical deep convection

    NASA Astrophysics Data System (ADS)

    McGee, Clayton J.

    Recent studies have noted the role of latent heating above the freezing level in reconciling Riehl and Malkus' Hot Tower Hypothesis (HTH) with evidence of diluted tropical deep convective cores. This study evaluates recent modifications to the HTH through Lagrangian trajectory analysis of deep convective cores in an idealized, high-resolution cloud-resolving model (CRM) simulation. A line of tropical convective cells develops within a high-resolution nested grid whose boundary conditions are obtained from a large-domain CRM simulation approaching radiative-convective equilibrium (RCE). Microphysical impacts on latent heating and equivalent potential temperature are analyzed along trajectories ascending within convective regions of the high-resolution nested grid. Changes in equivalent potential temperature along backward trajectories are partitioned into contributions from latent heating due to ice processes and a residual term. This residual term is composed of radiation and mixing. Due to the small magnitude of radiative heating rates in the convective inflow regions and updrafts examined here, the residual term is treated as an approximate representation of mixing within these regions. The simulations demonstrate that mixing with dry air decreases equivalent potential temperature along ascending trajectories below the freezing level, while latent heating due to freezing and vapor deposition increase equivalent potential temperature above the freezing level. The latent heating contributions along trajectories from cloud nucleation, condensation, evaporation, freezing, deposition, and sublimation are also quantified. Finally, the source regions of trajectories reaching the upper troposphere are identified; it is found that two-thirds of backward trajectories with starting points within strong updrafts or downdrafts above 10 km have their origin at levels higher than 2 km AGL. The importance of both boundary layer and mid-level inflow in moist environments is

  11. Joseph Black, carbon dioxide, latent heat, and the beginnings of the discovery of the respiratory gases.

    PubMed

    West, John B

    2014-06-15

    The discovery of carbon dioxide by Joseph Black (1728-1799) marked a new era of research on the respiratory gases. His initial interest was in alkalis such as limewater that were thought to be useful in the treatment of renal stone. When he studied magnesium carbonate, he found that when this was heated or exposed to acid, a gas was evolved that he called "fixed air" because it had been combined with a solid material. He showed that the new gas extinguished a flame, that it could not support life, and that it was present in gas exhaled from the lung. Within a few years of his discovery, hydrogen, nitrogen, and oxygen were also isolated. Thus arguably Black's work started the avalanche of research on the respiratory gases carried out by Priestley, Scheele, Lavoisier, and Cavendish. Black then turned his attention to heat and he was the first person to describe latent heat, that is the heat added or lost when a liquid changes its state, for example when water changes to ice or steam. Latent heat is a key concept in thermal physiology because of the heat lost when sweat evaporates. Black was a friend of the young James Watt (1736-1819) who was responsible for the development of early steam engines. Watt was puzzled why so much cooling was necessary to condense steam into water, and Black realized that the answer was the latent heat. The resulting improvements in steam engines ushered in the Industrial Revolution.

  12. Experimental simulation of latent heat thermal energy storage and heat pipe thermal transport for dish concentrator solar receiver

    NASA Technical Reports Server (NTRS)

    Narayanan, R.; Zimmerman, W. F.; Poon, P. T. Y.

    1981-01-01

    Test results on a modular simulation of the thermal transport and heat storage characteristics of a heat pipe solar receiver (HPSR) with thermal energy storage (TES) are presented. The HPSR features a 15-25 kWe Stirling engine power conversion system at the focal point of a parabolic dish concentrator operating at 827 C. The system collects and retrieves solar heat with sodium pipes and stores the heat in NaF-MgF2 latent heat storage material. The trials were run with a single full scale heat pipe, three full scale TES containers, and an air-cooled heat extraction coil to replace the Stirling engine heat exchanger. Charging and discharging, constant temperature operation, mixed mode operation, thermal inertial, etc. were studied. The heat pipe performance was verified, as were the thermal energy storage and discharge rates and isothermal discharges.

  13. The Measurement of the Specific Latent Heat of Fusion of Ice: Two Improved Methods.

    ERIC Educational Resources Information Center

    Mak, S. Y.; Chun, C. K. W.

    2000-01-01

    Suggests two methods for measuring the specific latent heat of ice fusion for high school physics laboratories. The first method is an ice calorimeter which is made from simple materials. The second method improves the thermal contact and allows for a more accurate measurement. Lists instructions for both methods. (Author/YDS)

  14. Effects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2017-02-01

    The growing number of observations of brown dwarfs (BDs) has provided evidence for strong atmospheric circulation on these objects. Directly imaged planets share similar observations and can be viewed as low-gravity versions of BDs. Vigorous condensate cycles of chemical species in their atmospheres are inferred by observations and theoretical studies, and latent heating associated with condensation is expected to be important in shaping atmospheric circulation and influencing cloud patchiness. We present a qualitative description of the mechanisms by which condensational latent heating influences circulation, and then illustrate them using an idealized general circulation model that includes a condensation cycle of silicates with latent heating and molecular weight effect due to the rainout of the condensate. Simulations with conditions appropriate for typical T dwarfs exhibit the development of localized storms and east–west jets. The storms are spatially inhomogeneous, evolving on a timescale of hours to days and extending vertically from the condensation level to the tropopause. The fractional area of the BD covered by active storms is small. Based on a simple analytic model, we quantitatively explain the area fraction of moist plumes and show its dependence on the radiative timescale and convective available potential energy (CAPE). We predict that if latent heating dominates cloud formation processes, the fractional coverage area of clouds decreases as the spectral type goes through the L/T transition from high to lower effective temperature. This is a natural consequence of the variation of the radiative timescale and CAPE with the spectral type.

  15. Daily evapotranspiration estimates by scaling instantaneous latent heat flux derived from a two-source model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Radiometric brightness temperature can be used in energy balance models that estimate sensible and latent heat fluxes of the land surface. However, brightness temperature is usually available only at one time of day when acquired from aircraft, fine-scale satellite platforms, or infrared thermometer...

  16. Robust estimates of soil moisture and latent heat flux coupling strength obtained from triple collocation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land surface models (LSMs) are often applied to predict the one-way coupling strength between surface soil moisture (SM) and surface latent heat (LH) flux. However, the ability of LSMs to accurately represent such coupling has not been adequately established. Likewise, the estimation of one-way SM/L...

  17. The role of individual cyclones for atmospheric latent and sensible heat transport into the European Arctic

    NASA Astrophysics Data System (ADS)

    Sodemann, H.; Stohl, A.

    2010-12-01

    The bulk of the atmospheric latent heat transport induced by extratropical cyclones is organized in the warm conveyor belt, also known as atmospheric rivers. In order to enhance the process understanding of atmospheric sensible and latent heat transport with these structures into the European Arctic, the magnitude and variability of the energy flux from individual cyclones in this region was studied. We applied a moisture source tracking algorithm embedded in the limited-area numerical weather prediction model (NWP) Climate High-Resolution Model (CHRM) to trace the evaporation sources and transport of water vapour from different latitude bands of the North Atlantic Ocean. September 2002 and December 2006 were chosen as initial analysis periods, since a particularly large number of cyclones (including former hurricanes) traveled within the North Atlantic storm track during these months. The main findings are that latent heat (LH) from more southerly source regions is transported at higher altitudes. Stronger storms draw latent heat from a larger area (further south), and the ensuing precipitation will hence on average originate from further south as well. Most long-range transport of LH occurs in the cold frontal bands. Individual cyclones are the main source of sub-monthly LH flux variability, and can cause up to 4-sigma variation of the mean flux. LH flux is almost permanently net positive (northward), unlike for sensible heat (SH) and other energy fluxes. Most LH that is "permanently" transferred to north of 60°N in the Atlantic storm track originates from directly south of that latitude, implying on average short atmospheric moisture lifetimes, and hence a fast energy turnover. We compare these findings to results from a Lagrangian moisture tracking method based on the FLEXPART model. Remarks with regard to differences in the transport conditions of latent head in such structures along the North American West Coast and the Norwegian West Coast will be made.

  18. Sensible and latent heat loss from the body surface of Holstein cows in a tropical environment.

    PubMed

    Maia, A S C; daSilva, R G; Battiston Loureiro, C M

    2005-09-01

    The general principles of the mechanisms of heat transfer are well known, but knowledge of the transition between evaporative and non-evaporative heat loss by Holstein cows in field conditions must be improved, especially for low-latitude environments. With this aim 15 Holstein cows managed in open pasture were observed in a tropical region. The latent heat loss from the body surface of the animals was measured by means of a ventilated capsule, while convective heat transfer was estimated by the theory of convection from a horizontal cylinder and by the long-wave radiation exchange based on the Stefan-Boltzmann law. When the air temperature was between 10 and 36 degrees C the sensible heat transfer varied from 160 to -30 W m(-2), while the latent heat loss by cutaneous evaporation increased from 30 to 350 W m(-2). Heat loss by cutaneous evaporation accounted for 20-30% of the total heat loss when air temperatures ranged from 10 to 20 degrees C. At air temperatures >30 degrees C cutaneous evaporation becomes the main avenue of heat loss, accounting for approximately 85% of the total heat loss, while the rest is lost by respiratory evaporation.

  19. Extracellular heat shock protein HSP90{beta} secreted by MG63 osteosarcoma cells inhibits activation of latent TGF-{beta}1

    SciTech Connect

    Suzuki, Shigeki; Kulkarni, Ashok B.

    2010-07-30

    Transforming growth factor-beta 1 (TGF-{beta}1) is secreted as a latent complex, which consists of latency-associated peptide (LAP) and the mature ligand. The release of the mature ligand from LAP usually occurs through conformational change of the latent complex and is therefore considered to be the first step in the activation of the TGF-{beta} signaling pathway. So far, factors such as heat, pH changes, and proteolytic cleavage are reportedly involved in this activation process, but the precise molecular mechanism is still far from clear. Identification and characterization of the cell surface proteins that bind to LAP are important to our understanding of the latent TGF-{beta} activation process. In this study, we have identified heat shock protein 90 {beta} (HSP90{beta}) from the cell surface of the MG63 osteosarcoma cell line as a LAP binding protein. We have also found that MG63 cells secrete HSP90{beta} into extracellular space which inhibits the activation of latent TGF-{beta}1, and that there is a subsequent decrease in cell proliferation. TGF-{beta}1-mediated stimulation of MG63 cells resulted in the increased cell surface expression of HSP90{beta}. Thus, extracellular HSP90{beta} is a negative regulator for the activation of latent TGF-{beta}1 modulating TGF-{beta} signaling in the extracellular domain. -- Research highlights: {yields} Transforming growth factor-beta 1 (TGF-{beta}1) is secreted as a latent complex. {yields} This complex consists of latency-associated peptide (LAP) and the mature ligand. {yields} The release of the mature ligand from LAP is the first step in TGF-{beta} activation. {yields} We identified for the first time a novel mechanism for this activation process. {yields} Heat shock protein 90 {beta} is discovered as a negative regulator for this process.

  20. Combining Satellite Microwave Radiometer and Radar Observations to Estimate Atmospheric Latent Heating Profiles

    NASA Technical Reports Server (NTRS)

    Grecu, Mircea; Olson, William S.; Shie, Chung-Lin; L'Ecuyer, Tristan S.; Tao, Wei-Kuo

    2009-01-01

    In this study, satellite passive microwave sensor observations from the TRMM Microwave Imager (TMI) are utilized to make estimates of latent + eddy sensible heating rates (Q1-QR) in regions of precipitation. The TMI heating algorithm (TRAIN) is calibrated, or "trained" using relatively accurate estimates of heating based upon spaceborne Precipitation Radar (PR) observations collocated with the TMI observations over a one-month period. The heating estimation technique is based upon a previously described Bayesian methodology, but with improvements in supporting cloud-resolving model simulations, an adjustment of precipitation echo tops to compensate for model biases, and a separate scaling of convective and stratiform heating components that leads to an approximate balance between estimated vertically-integrated condensation and surface precipitation. Estimates of Q1-QR from TMI compare favorably with the PR training estimates and show only modest sensitivity to the cloud-resolving model simulations of heating used to construct the training data. Moreover, the net condensation in the corresponding annual mean satellite latent heating profile is within a few percent of the annual mean surface precipitation rate over the tropical and subtropical oceans where the algorithm is applied. Comparisons of Q1 produced by combining TMI Q1-QR with independently derived estimates of QR show reasonable agreement with rawinsonde-based analyses of Q1 from two field campaigns, although the satellite estimates exhibit heating profile structure with sharper and more intense heating peaks than the rawinsonde estimates. 2

  1. Computational Evaluation of a Latent Heat Energy Storage System

    DTIC Science & Technology

    2013-01-01

    Release; Distribution Unlimited. PA#13098 13. SUPPLEMENTARY NOTES Journal Article submitted to Solar Energy Materials and Solar Cells. 14. ABSTRACT...A system capable of receiving, absorbing, and converting solar energy was designed for use on a satellite in low Earth orbit. The proposed system, an...fronts the amount of solar irradiation required to fully utilize the phase change material was determined to be between 4 and 5 kW depending on the orbit

  2. Latent Heat Thermal Energy Storage: Effect of Metallic Mesh Size on Storage Time and Capacity

    NASA Astrophysics Data System (ADS)

    Shuja, S. Z.; Yilbas, B. S.

    2015-11-01

    Use of metallic meshes in latent heat thermal storage system shortens the charging time (total melting of the phase change material), which is favorable in practical applications. In the present study, effect of metallic mesh size on the thermal characteristics of latent heat thermal storage system is investigated. Charging time is predicted for various mesh sizes, and the influence of the amount of mesh material on the charging capacity is examined. An experiment is carried out to validate the numerical predictions. It is found that predictions of the thermal characteristics of phase change material with presence of metallic meshes agree well with the experimental data. High conductivity of the metal meshes enables to transfer heat from the edges of the thermal system towards the phase change material while forming a conduction tree in the system. Increasing number of meshes in the thermal system reduces the charging time significantly due to increased rate of conduction heat transfer in the thermal storage system; however, increasing number of meshes lowers the latent heat storage capacity of the system.

  3. Extracellular heat shock protein HSP90beta secreted by MG63 osteosarcoma cells inhibits activation of latent TGF-beta1.

    PubMed

    Suzuki, Shigeki; Kulkarni, Ashok B

    2010-07-30

    Transforming growth factor-beta 1 (TGF-beta1) is secreted as a latent complex, which consists of latency-associated peptide (LAP) and the mature ligand. The release of the mature ligand from LAP usually occurs through conformational change of the latent complex and is therefore considered to be the first step in the activation of the TGF-beta signaling pathway. So far, factors such as heat, pH changes, and proteolytic cleavage are reportedly involved in this activation process, but the precise molecular mechanism is still far from clear. Identification and characterization of the cell surface proteins that bind to LAP are important to our understanding of the latent TGF-beta activation process. In this study, we have identified heat shock protein 90 beta (HSP90beta) from the cell surface of the MG63 osteosarcoma cell line as a LAP binding protein. We have also found that MG63 cells secrete HSP90beta into extracellular space which inhibits the activation of latent TGF-beta1, and that there is a subsequent decrease in cell proliferation. TGF-beta1-mediated stimulation of MG63 cells resulted in the increased cell surface expression of HSP90beta. Thus, extracellular HSP90beta is a negative regulator for the activation of latent TGF-beta1 modulating TGF-beta signaling in the extracellular domain.

  4. Experimental and numerical study of latent heat thermal energy storage systems assisted by heat pipes for concentrated solar power application

    NASA Astrophysics Data System (ADS)

    Tiari, Saeed

    A desirable feature of concentrated solar power (CSP) with integrated thermal energy storage (TES) unit is to provide electricity in a dispatchable manner during cloud transient and non-daylight hours. Latent heat thermal energy storage (LHTES) offers many advantages such as higher energy storage density, wider range of operating temperature and nearly isothermal heat transfer relative to sensible heat thermal energy storage (SHTES), which is the current standard for trough and tower CSP systems. Despite the advantages mentioned above, LHTES systems performance is often limited by low thermal conductivity of commonly used, low cost phase change materials (PCMs). Research and development of passive heat transfer devices, such as heat pipes (HPs) to enhance the heat transfer in the PCM has received considerable attention. Due to its high effective thermal conductivity, heat pipe can transport large amounts of heat with relatively small temperature difference. The objective of this research is to study the charging and discharging processes of heat pipe-assisted LHTES systems using computational fluid dynamics (CFD) and experimental testing to develop a method for more efficient energy storage system design. The results revealed that the heat pipe network configurations and the quantities of heat pipes integrated in a thermal energy storage system have a profound effect on the thermal response of the system. The optimal placement of heat pipes in the system can significantly enhance the thermal performance. It was also found that the inclusion of natural convection heat transfer in the CFD simulation of the system is necessary to have a realistic prediction of a latent heat thermal storage system performance. In addition, the effects of geometrical features and quantity of fins attached to the HPs have been studied.

  5. A neural network to retrieve the mesoscale instantaneous latent heat flux over oceans from SSM/I observations

    NASA Technical Reports Server (NTRS)

    Bourras, D.; Eymard, L.; Liu, W. T.

    2000-01-01

    The turbulent latent and sensible heat fluxes are necessary to study heat budget of the upper ocean or initialize ocean general circulation models. In order to retrieve the latent heat flux from satellite observations authors mostly use a bulk approximation of the flux whose parameters are derived from different instrument. In this paper, an approach based on artificial neural networks is proposed and compared to the bulk method on a global data set and 3 local data sets.

  6. Copper-Silicon-Magnesium Alloys for Latent Heat Storage

    NASA Astrophysics Data System (ADS)

    Gibbs, P. J.; Withey, E. A.; Coker, E. N.; Kruizenga, A. M.; Andraka, C. E.

    2016-12-01

    The systematic development of microstructure, solidification characteristics, and heat of solidification with composition in copper-silicon-magnesium alloys for thermal energy storage is presented. Differential scanning calorimetry was used to relate the thermal characteristics to microstructural development in the investigated alloys and clarifies the location of one of the terminal three-phase eutectics. Repeated thermal cycling highlights the thermal storage stability of the transformation through multiple melting events. Two near-terminal eutectic alloys display high enthalpies of solidification, relatively narrow melting ranges, and stable transformation hysteresis behaviors suited to thermal energy storage.

  7. Copper-silicon-magnesium alloys for latent heat storage

    SciTech Connect

    Gibbs, P. J.; Withey, E. A.; Coker, E. N.; Kruizenga, A. M.; Andraka, C. E.

    2016-06-21

    The systematic development of microstructure, solidification characteristics, and heat of solidification with composition in copper-silicon-magnesium alloys for thermal energy storage is presented. Differential scanning calorimetry was used to relate the thermal characteristics to microstructural development in the investigated alloys and clarifies the location of one of the terminal three-phase eutectics. Repeated thermal cycling highlights the thermal storage stability of the transformation through multiple melting events. In conclusion, two near-terminal eutectic alloys display high enthalpies of solidification, relatively narrow melting ranges, and stable transformation hysteresis behaviors suited to thermal energy storage.

  8. Convective and Stratiform Precipitation Processes and their Relationship to Latent Heating

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, Steve; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

    2009-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. An improved convective -stratiform heating (CSH) algorithm has been developed to obtain the 3D structure of cloud heating over the Tropics based on two sources of information: 1) rainfall information, namely its amount and the fraction due to light rain intensity, observed directly from the Precipitation Radar (PR) on board the TRMM satellite and 2) synthetic cloud physics information obtained from cloud-resolving model (CRM) simulations of cloud systems. The cloud simulations provide details on cloud processes, specifically latent heating, eddy heat flux convergence and radiative heating/cooling, that. are not directly observable by satellite. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. One of the major differences between new and old algorithms is that the level of maximum cloud heating occurs 1 to 1.5 km lower in the atmosphere in the new algorithm. This can effect the structure of the implied air currents associated with the general circulation of the atmosphere in the Tropics. The new CSH algorithm will be used provide retrieved heating data to other heating algorithms to supplement their performance.

  9. The study of latent heat transport characteristics by solid particles and saccharide solution mixtures

    NASA Astrophysics Data System (ADS)

    Morita, Shin-ichi; Hayamizu, Yasutaka; Inaba, Hideo

    2011-06-01

    The purpose of this study is the development of latent heat transport system by using the mixture of the minute latent heat storage materials and the saccharine solution as medium. The experimental studies are carried out by the evaluation of viscosity and pressure loss in a pipe. Polyethylene (P.E.) is selected as the dispersed minute material that has closeness density (920kg/m3) of ice (917kg/m3). D-sorbitol and D-xylose solutions are picked as continuum phase of the test mixture. The concentration of D-sorbitol solution is set 48mass% from measured results of saturation solubility and the melting point. 40mass% solution of D-xylose is selected as the other test continuum phase. The non-ion surfactant, EA157 Dai-ichiseiyaku CO. Ltd, is used in order to prevent of dispersed P.E. powder cohere. The pressure loss of test mixture is measured by the straight circular pipe that has smooth inner surface. The measuring length for pressure loss is 1000 mm, and the inner diameter of pipe is 15mm. The accuracy of experiment apparatus for measuring pressure loss is within ±5%. The pressure loss data is estimated by the relationship between the heat transport ratio and the required pump power. It is clarified that the optimum range of mixing ratio exists over 10mass% of latent heat storage material.

  10. Latent Heating Retrieval from TRMM Observations Using a Simplified Thermodynamic Model

    NASA Technical Reports Server (NTRS)

    Grecu, Mircea; Olson, William S.

    2003-01-01

    A procedure for the retrieval of hydrometeor latent heating from TRMM active and passive observations is presented. The procedure is based on current methods for estimating multiple-species hydrometeor profiles from TRMM observations. The species include: cloud water, cloud ice, rain, and graupel (or snow). A three-dimensional wind field is prescribed based on the retrieved hydrometeor profiles, and, assuming a steady-state, the sources and sinks in the hydrometeor conservation equations are determined. Then, the momentum and thermodynamic equations, in which the heating and cooling are derived from the hydrometeor sources and sinks, are integrated one step forward in time. The hydrometeor sources and sinks are reevaluated based on the new wind field, and the momentum and thermodynamic equations are integrated one more step. The reevalution-integration process is repeated until a steady state is reached. The procedure is tested using cloud model simulations. Cloud-model derived fields are used to synthesize TRMM observations, from which hydrometeor profiles are derived. The procedure is applied to the retrieved hydrometeor profiles, and the latent heating estimates are compared to the actual latent heating produced by the cloud model. Examples of procedure's applications to real TRMM data are also provided.

  11. Metal-halide mixtures for latent heat energy storage

    NASA Technical Reports Server (NTRS)

    Chen, K.; Manvi, R.

    1981-01-01

    Alkali metal and alkali halide mixtures are identified which may be suitable for thermal energy storage at temperatures above 600 C. The use of metal-halides is appropriate because of their tendency to form two immiscible melts with a density difference, which reduces scale formation and solidification on heat transfer surfaces. Also, the accumulation of phase change material along the melt interface is avoided by the self-dispersing characteristic of some metal-halides, in particular Sr-SrCl2, Ba-BaCl2, and Ba-BaBr2 mixtures. Further advantages lie in their high thermal conductivities, ability to cope with thermal shock, corrosion inhibition, and possibly higher energy densities.

  12. Spectral Retrieval of Latent Heating Profiles from TRMM PR Data: Comparison of Look-Up Tables

    NASA Technical Reports Server (NTRS)

    Shige, Shoichi; Takayabu, Yukari N.; Tao, Wei-Kuo; Johnson, Daniel E.; Shie, Chung-Lin

    2003-01-01

    The primary goal of the Tropical Rainfall Measuring Mission (TRMM) is to use the information about distributions of precipitation to determine the four dimensional (i.e., temporal and spatial) patterns of latent heating over the whole tropical region. The Spectral Latent Heating (SLH) algorithm has been developed to estimate latent heating profiles for the TRMM Precipitation Radar (PR) with a cloud- resolving model (CRM). The method uses CRM- generated heating profile look-up tables for the three rain types; convective, shallow stratiform, and anvil rain (deep stratiform with a melting level). For convective and shallow stratiform regions, the look-up table refers to the precipitation top height (PTH). For anvil region, on the other hand, the look- up table refers to the precipitation rate at the melting level instead of PTH. For global applications, it is necessary to examine the universality of the look-up table. In this paper, we compare the look-up tables produced from the numerical simulations of cloud ensembles forced with the Tropical Ocean Global Atmosphere (TOGA) Coupled Atmosphere-Ocean Response Experiment (COARE) data and the GARP Atlantic Tropical Experiment (GATE) data. There are some notable differences between the TOGA-COARE table and the GATE table, especially for the convective heating. First, there is larger number of deepest convective profiles in the TOGA-COARE table than in the GATE table, mainly due to the differences in SST. Second, shallow convective heating is stronger in the TOGA COARE table than in the GATE table. This might be attributable to the difference in the strength of the low-level inversions. Third, altitudes of convective heating maxima are larger in the TOGA COARE table than in the GATE table. Levels of convective heating maxima are located just below the melting level, because warm-rain processes are prevalent in tropical oceanic convective systems. Differences in levels of convective heating maxima probably reflect

  13. Uncertainty in Tropical Ocean Latent Heat Flux Variability During the Last 25 Years

    NASA Technical Reports Server (NTRS)

    Robertson, F. R.; Lu, H.-I.; Bosilovich, M. G.; Miller, T. L.

    2007-01-01

    When averaged over the tropical oceans (30deg N/S), latent heat flux anomalies derived from passive microwave satellite measurements as well as reanalyses and climate models driven with specified seal-surface temperatures show considerable disagreement in their decadal trends. These estimates range from virtually no trend to values over 8.4 W/sq m decade. Satellite estimates also tend to have a larger interannual signal related to El Nino/Southern Oscillation (ENSO) events than do reanalyses or model simulations. An analysis of wind speed and humidity going into bulk aerodynamic calculations used to derive these fluxes reveals several error sources. Among these are apparent remaining intercalibration issues affecting passive microwave satellite 10 m wind speeds and systematic biases in retrieval of near-surface humidity. Likewise, reanalyses suffer from discontinuities in availability of assimilated data that affect near surface meteorological variables. The results strongly suggest that current latent heat flux trends are overestimated.

  14. Cold Heat Storage Characteristics of O/W-type Latent Heat Emulsion Including Continuum Phase of Water Treated with a Freezing Point Depression

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Morita, Shin-Ichi

    This paper deals with flow and cold heat storage characteristics of the oil (tetradecane, C14H30, freezing point 278.9 K, Latent heat 229 kJ/kg)/water emulsion as a latent heat storage material having a low melting point. The test emulsion includes a water-urea solution as a continuum phase. The freezing point depression of the continuum phase permits enhancement of the heat transfer rate of the emulison, due to the large temperature difference between the latent heat storage material and water-urea solution. The velocity of emulsion flow and the inlet temperature of coolant in a coiled double tube heat exchanger are chosen as the experimental parameters. The pressure drop, the heat transfer coefficient of the emulsion in the coiled tube are measured in the temperture region over solid and liquid phase of the latent heat storage material. The finishing time of the cold heat storage is defined experimentally in the range of sensible and latent heat storage. It is clarified that the flow behavior of the emulsion as a non-Newtonian fluid has an important role in cold heat storage. The useful nondimentional correlation equations for the additional pressure loss coefficient, the heat transfer coefficient and the finishing time of the cold heat storage are derived in terms of Dean number and heat capacity ratio.

  15. Latent Heat and Sensible Heat Fluxes Simulation in Maize Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Safa, B.

    2015-12-01

    Latent Heat (LE) and Sensible Heat (H) flux are two major components of the energy balance at the earth's surface which play important roles in the water cycle and global warming. There are various methods for their estimation or measurement. Eddy covariance is a direct and accurate technique for their measurement. Some limitations lead to prevention of the extensive use of the eddy covariance technique. Therefore, simulation approaches can be utilized for their estimation. ANNs are the information processing systems, which can inspect the empirical data and investigate the relations (hidden rules) among them, and then make the network structure. In this study, multi-layer perceptron neural network trained by the steepest descent Back-Propagation (BP) algorithm was tested to simulate LE and H flux above two maize sites (rain-fed & irrigated) near Mead, Nebraska. Network training and testing was fulfilled using hourly data of including year, local time of day (DTime), leaf area index (LAI), soil water content (SWC) in 10 and 25 cm depths, soil temperature (Ts) in 10 cm depth, air temperature (Ta), vapor pressure deficit (VPD), wind speed (WS), irrigation and precipitation (P), net radiation (Rn), and the fraction of incoming Photosynthetically Active Radiation (PAR) absorbed by the canopy (fPAR), which were selected from days of year (DOY) 169 to 222 for 2001, 2003, 2005, 2007, and 2009. The results showed high correlation between actual and estimated data; the R² values for LE flux in irrigated and rain-fed sites were 0.9576, and 0.9642; and for H flux 0.8001, and 0.8478, respectively. Furthermore, the RMSE values ranged from 0.0580 to 0.0721 W/m² for LE flux and from 0.0824 to 0.0863 W/m² for H flux. In addition, the sensitivity of the fluxes with respect to each input was analyzed over the growth stages. Thus, the most powerful effects among the inputs for LE flux were identified net radiation, leaf area index, vapor pressure deficit, wind speed, and for H

  16. Experimental analysis of regularly structured composite latent heat storages for temporary cooling of electronic components

    NASA Astrophysics Data System (ADS)

    Lohse, Ekkehard; Schmitz, Gerhard

    2013-11-01

    This study presents the experimental investigation of regularly structured Composite Latent Heat Storages. Solid-liquid Phase Change Materials have a low thermal conductivity, resulting in high temperature differences. This drawback is compensated by the combination with specially designed frame-structures made of aluminum to enhance the transport of thermal energy. A prototype is investigated experimentally on a test rig, where the heat load and temperatures are measured while the phase change process is observed optically, and compared to a solid block Phase Change Material.

  17. Influence of latent heat and thermal diffusion on the growth of nematic liquid crystal nuclei.

    PubMed

    Huisman, B A H; Fasolino, A

    2007-08-01

    The growth of nematic liquid crystal nuclei from an isotropic melt follows a power law behavior with exponent n found experimentally to vary between 1/2 for low quench depths, up to 1 for high quench depths. This behavior has been attributed to the competition between curvature and free energy. We show that curvature cannot account for the low quench depth behavior of the nucleus growth, and attribute this behavior to the diffusion of latent heat. We use a multiscale approach to solve the Landau-Ginzburg order parameter evolution equation coupled to a diffusive heat equation, and discuss this behavior for material parameters experimentally measured for the liquid crystal 8CB.

  18. New latent heat storage system with nanoparticles for thermal management of electric vehicles

    NASA Astrophysics Data System (ADS)

    Javani, N.; Dincer, I.; Naterer, G. F.

    2014-12-01

    In this paper, a new passive thermal management system for electric vehicles is developed. A latent heat thermal energy storage with nanoparticles is designed and optimized. A genetic algorithm method is employed to minimize the length of the heat exchanger tubes. The results show that even the optimum length of a shell and tube heat exchanger becomes too large to be employed in a vehicle. This is mainly due to the very low thermal conductivity of phase change material (PCM) which fills the shell side of the heat exchanger. A carbon nanotube (CNT) and PCM mixture is then studied where the probability of nanotubes in a series configuration is defined as a deterministic design parameter. Various heat transfer rates, ranging from 300 W to 600 W, are utilized to optimize battery cooling options in the heat exchanger. The optimization results show that smaller tube diameters minimize the heat exchanger length. Furthermore, finned tubes lead to a higher heat exchanger length due to more heat transfer resistance. By increasing the CNT concentration, the optimum length of the heat exchanger decreases and makes the improved thermal management system a more efficient and competitive with air and liquid thermal management systems.

  19. Eddy covariance measurement of carbon, latent and sensible heat fluxes from western Lake Erie

    NASA Astrophysics Data System (ADS)

    Shao, C.; Chen, J.; Stepien, C.; Bridgeman, T.; Czajkowski, K. P.; Becker, R.; Chu, H.; yang, Z.

    2013-12-01

    Long-term measurements of sensible and latent heat and carbon dioxide fluxes were performed over a boreal lake in northern American using the direct micrometeorological eddy covariance (EC) technique. Two permanent EC flux stations in western Lake Erie - Crib (41.7167N, 83.2667W, nearest distance from shore is 4.5 km) and Light (41.8314N, 83.2006W, nearest distance from shore > 12 km) sites have been operating since September, 2011. In 2012, in both sites, the sensible heat flux had its minimum in the afternoon (15:00-17:00) and peaked in the early morning (7:00-9:00) in August-November, varied from -4 W m-2 to +30 W m-2. The diurnal amplitude of H was largest in spring and in early fall (30 W m-2 in September) whereas it was smaller in July and August (20 W m-2). The latent heat flux had obvious seasonal pattern in both sites with higher values in the summer, while it did not show obvious daily courses, even did not have the day and night variation in both sites, only one trend from June to October was higher at night than during the daytime in Light site. The maximum latent heat of ~180 W m-2 in summer whereas the minimum -10 W m-2 in winter were observed. The latent heat flux dominated clearly over the sensible heat in spring and summer; that is, the Bowen ratio was less than 1 and most of the energy absorbed by the water was consumed in terms of evapotranspiration. A lookup table method was performed data gap-filling in our aquatic ecosystems in order to obtain the continuously daily, monthly and yearly carbon and water budgets. In 2012, for the annual cumulative total, the evapotranspiration was 820 and 700 mm (about 2000 and 1700 MJ m-2) in Crib and Light sites, respectively, comparing with the annual rainfall of 700 mm. The annual sensible heat was 480 and 300 MJ m-2 in Crib and Light sites, respectively. And there were four and five CO2 uptake months in Crib and Light sites, respectively. The maximum CO2 uptake month was in July in both sites, with -28 and

  20. Comparison of chemical and heating methods to enhance latent fingerprint deposits on thermal paper.

    PubMed

    Bond, John W

    2014-03-01

    A comparison is made of proprietary methods to develop latent fingerprint deposits on the inked side of thermal paper using either chemical treatment (Thermanin) or the application of heat to the paper (Hot Print System). Results with a trial of five donors show that the application of heat produces statistically significantly more fingerprint ridge detail than the chemical treatment for both fingerprint deposits aged up to 4 weeks and for a nine sequence depletion series. Subjecting the thermal paper to heat treatment with the Hot Print System did not inhibit subsequent ninhydrin chemical development of fingerprint deposits on the noninked side of the paper. A further benefit of the application of heat is the rapid development of fingerprint deposits (less than a minute) compared with up to 12 h for the Thermanin chemical treatment.

  1. Computational modeling of latent-heat-storage in PCM modified interior plaster

    NASA Astrophysics Data System (ADS)

    Fořt, Jan; Maděra, Jiří; Trník, Anton; Pavlíková, Milena; Pavlík, Zbyšek

    2016-06-01

    The latent heat storage systems represent a promising way for decrease of buildings energy consumption with respect to the sustainable development principles of building industry. The presented paper is focused on the evaluation of the effect of PCM incorporation on thermal performance of cement-lime plasters. For basic characterization of the developed materials, matrix density, bulk density, and total open porosity are measured. Thermal conductivity is accessed by transient impulse method. DSC analysis is used for the identification of phase change temperature during the heating and cooling process. Using DSC data, the temperature dependent specific heat capacity is calculated. On the basis of the experiments performed, the supposed improvement of the energy efficiency of characteristic building envelope system where the designed plasters are likely to be used is evaluated by a computational analysis. Obtained experimental and computational results show a potential of PCM modified plasters for improvement of thermal stability of buildings and moderation of interior climate.

  2. Evaporative cooling: effective latent heat of evaporation in relation to evaporation distance from the skin.

    PubMed

    Havenith, George; Bröde, Peter; den Hartog, Emiel; Kuklane, Kalev; Holmer, Ingvar; Rossi, Rene M; Richards, Mark; Farnworth, Brian; Wang, Xiaoxin

    2013-03-15

    Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available, which has found little use in recent literature. In this experiment a thermal manikin, (MTNW, Seattle, WA) was used to determine the effective cooling power of moisture evaporation. The manikin measures both heat loss and mass loss independently, allowing a direct calculation of an effective latent heat of evaporation (λeff). The location of the evaporation was varied: from the skin or from the underwear or from the outerwear. Outerwear of different permeabilities was used, and different numbers of layers were used. Tests took place in 20°C, 0.5 m/s at different humidities and were performed both dry and with a wet layer, allowing the breakdown of heat loss in dry and evaporative components. For evaporation from the skin, λeff is close to the theoretical value (2,430 J/g) but starts to drop when more clothing is worn, e.g., by 11% for underwear and permeable coverall. When evaporation is from the underwear, λeff reduction is 28% wearing a permeable outer. When evaporation is from the outermost layer only, the reduction exceeds 62% (no base layer), increasing toward 80% with more layers between skin and wet outerwear. In semi- and impermeable outerwear, the added effect of condensation in the clothing opposes this effect. A general formula for the calculation of λeff was developed.

  3. Effects of latent heating on driving atmospheric circulation of brown dwarfs and directly imaged giant planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2015-12-01

    Growing observations of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs), such as brightness variability and surface maps have provided evidence for strong atmospheric circulation on these worlds. Previous studies that serve to understand the atmospheric circulation of BDs include modeling of convection from the interior and its interactions with stably stratified atmospheres. These models show that such interactions can drive an atmospheric circulation, forming zonal jets and/or vortices. However, these models are dry, not including condensation of various chemical species. Latent heating from condensation of water has previously been shown to play an important role on driving the zonal jets on four giant planets in our solar system. As such, condensation cycles of various chemical species are believed to be an important source in driving the atmospheric circulation of BDs and directly imaged EGPs. Here we present results from three-dimensional simulations for the atmospheres of BDs and EGPs based on a general circulation model that includes the effect of a condensate cycle. Large-scale latent heating and molecular weight effect due to condensation of a single species are treated explicitly. We examine the circulation patterns caused by large-scale latent heating which results from condensation of silicate vapor in hot dwarfs and water vapor in the cold dwarfs. By varying the abundance of condensable vapor and the radiative timescale, we conclude that under normal atmospheric conditions of BDs (hot and thus with relatively short radiative timescale), latent heating alone by silicate vapor is unable to drive a global circulation, leaving a quiescent atmosphere, because of the suppression to moist instability by downward transport of dry air. Models with relatively long radiative timescale, which may be the case for cooler bodies, tend to maintain an active hydrological cycle and develop zonal jets. Once condensation happens, storms driven by

  4. Phase Change Characteristics of a Nanoemulsion as a Latent Heat Storage Material

    NASA Astrophysics Data System (ADS)

    Fumoto, Koji; Sato, Noriaki; Kawaji, Masahiro; Kawanami, Tsuyoshi; Inamura, Takao

    2014-10-01

    The primary objective of this study was to investigate the fundamental phase change characteristics of a nanoemulsion using differential scanning calorimetry (DSC). Tetradecane, which has a slightly higher melting point than water, was utilized as the phase change material for the nanoemulsion. The melting point of the nanoemulsion, the melting peak temperature, and latent heat were examined in detail. Regarding the fundamental phase change characteristics of the nanoemulsion, it was found that its phase change characteristics were strongly affected by the temperature-scanning rate of the DSC. Moreover, it was confirmed that the phase change behavior does not change with repeated solidification and melting.

  5. A methodology for mapping forest latent heat flux densities using remote sensing

    NASA Technical Reports Server (NTRS)

    Pierce, Lars L.; Congalton, Russell G.

    1988-01-01

    Surface temperatures and reflectances of an upper elevation Sierran mixed conifer forest were monitored using the Thematic Mapper Simulator sensor during the summer of 1985 in order to explore the possibility of using remote sensing to determine the distribution of solar energy on forested watersheds. The results show that the method is capable of quantifying the relative energy allocation relationships between the two cover types defined in the study. It is noted that the method also has the potential to map forest latent heat flux densities.

  6. Combined solar heat and power system with a latent heat storage - system simulations for an economic assessment

    NASA Astrophysics Data System (ADS)

    Zipf, Verena; Neuhäuser, Anton

    2016-05-01

    Decentralized solar combined heat and power (CHP) systems can be economically feasible, especially when they have a thermal storage. In such systems, heat provided by solar thermal collectors is used to generate electricity and useful heat for e.g. industrial processes. For the supply of energy in times without solar irradiation, a thermal storage can be integrated. In this work, the performance of a solar CHP system using an active latent heat storage with a screw heat exchanger is investigated. Annual yield calculations are conducted in order to calculate annual energy gains and, based on them; economic assumptions are used to calculated economic numbers in order to assess the system performance. The energy savings of a solar system, compared to a system with a fossil fuel supply, are calculated. Then the net present value and the dynamic payback are calculated with these savings, the initial investment costs and the operational costs. By interpretation and comparison of these economic numbers, an optimum system design in terms of solar field size and storage size was determined. It has been shown that the utilization of such systems can be economical in remote areas without gas and grid connection. Optimal storage design parameters in terms of the temperature differences in the heat exchanger and the storage capacity have been determined which can further increase the net present value of such system.

  7. Passive and Active Microwave Remote Sensing of Precipitation and Latent Heating Distributions in the Tropics from TRMM

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Haddad, Ziad S.; Tao, Wei-Kuo; Wang, Yansen; Lang, Stephen E.; Braun, Scott A.; Chiu, Christine; Wang, Jian-Jian

    2002-01-01

    Passive and active microwave remote sensing data are analyzed to identify signatures of precipitation and vertical motion in tropical convection. A database of cloud/radiative model simulations is used to quantify surface rain rates and latent heating profiles that are consistent with these signatures. At satellite footprint-scale (approximately 10 km), rain rate and latent heating estimates are subject to significant random errors, but by averaging the estimates in space and time, random errors are substantially reduced, Bias errors have been minimized by improving the microphysics in the supporting cloud/radiative model simulations, and by imposing a consistent definition of remotely-sensed and model-simulated convective/stratiform rain coverage. Remotely-sensed precipitation and latent heating distributions in the tropics are derived from Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave/ Imager (SSM/ I) sensor data. The prototype Version 6 TRMM passive microwave algorithm typically yields average heating profiles with maxima between 6 and 7 km altitude for organized mesoscale convective systems. Retrieved heating profiles for individual convective systems are compared to coincident estimates based upon a combination of dual-Doppler radar and rawinsonde data. Also, large-scale latent heating distributions are compared to estimates derived from a simpler technique that utilizes observations of surface rain rate and stratiform rain proportion to infer vertical heating structure. Results of these tests will be presented at the conference.

  8. Conceptual design of a latent heat thermal energy storage subsystem for a saturated steam solar receiver and load

    NASA Astrophysics Data System (ADS)

    Dilauro, G. F.; Rice, R. E.

    1982-02-01

    The conceptual design of a tube intensive latent heat thermal energy storage (TES) subsystem which utilized a eutectic mixture of sodium hydroxide and sodium nitrate as the phase change material (PCM) was developed. The charging and discharging of the unit is accomplished by the same serpentine tube bundle heat exchanger in which heat transfer is augmented by aluminum channels acting as fins. Every tenth channel is made of steel to provide tube support.

  9. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.; Knowles, G. R.; Mathur, A. K.; Budimir, J.

    1979-01-01

    Active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250 C to 350 C, using the heat of fusion of molten salts for storing thermal energy are described. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange concepts for heat transfer during solidification are conceived and conceptually designed for use with selected storage media. The concepts are analyzed for their scalability, maintenance, safety, technological development and costs. A model for estimating and scaling storage system costs is developed and is used for economic evaluation of salt mixtures and heat exchange concepts for a large scale application. The importance of comparing salts and heat exchange concepts on a total system cost basis, rather than the component cost basis alone, is pointed out. The heat exchange concepts were sized and compared for 6.5 MPa/281 C steam conditions and a 1000 MW(t) heat rate for six hours. A cost sensitivity analysis for other design conditions is also carried out.

  10. Latent heat induced rotation limited aggregation in 2D ice nanocrystals

    NASA Astrophysics Data System (ADS)

    Bampoulis, Pantelis; Siekman, Martin H.; Kooij, E. Stefan; Lohse, Detlef; Zandvliet, Harold J. W.; Poelsema, Bene

    2015-07-01

    The basic science responsible for the fascinating shapes of ice crystals and snowflakes is still not understood. Insufficient knowledge of the interaction potentials and the lack of relevant experimental access to the growth process are to blame for this failure. Here, we study the growth of fractal nanostructures in a two-dimensional (2D) system, intercalated between mica and graphene. Based on our scanning tunneling spectroscopy data, we provide compelling evidence that these fractals are 2D ice. They grow while they are in material contact with the atmosphere at 20 °C and without significant thermal contact to the ambient. The growth is studied in situ, in real time and space at the nanoscale. We find that the growing 2D ice nanocrystals assume a fractal shape, which is conventionally attributed to Diffusion Limited Aggregation (DLA). However, DLA requires a low mass density mother phase, in contrast to the actual currently present high mass density mother phase. Latent heat effects and consequent transport of heat and molecules are found to be key ingredients for understanding the evolution of the snow (ice) flakes. We conclude that not the local availability of water molecules (DLA), but rather them having the locally required orientation is the key factor for incorporation into the 2D ice nanocrystal. In combination with the transport of latent heat, we attribute the evolution of fractal 2D ice nanocrystals to local temperature dependent rotation limited aggregation. The ice growth occurs under extreme supersaturation, i.e., the conditions closely resemble the natural ones for the growth of complex 2D snow (ice) flakes and we consider our findings crucial for solving the "perennial" snow (ice) flake enigma.

  11. Materials compatibility in Dish-Stirling solar generators using Cu-Si-Mg eutectic for latent heat storage

    NASA Astrophysics Data System (ADS)

    Kruizenga, A. M.; Withey, E. A.; Andraka, C. E.; Gibbs, P. J.

    2016-05-01

    Dish-Stirling systems are a strong candidate to meet cost production goals for solar thermal power production. Thermal energy storage improves the capacity factor of thermal power systems; copper-silicon-magnesium eutectic alloys have been investigated as potential latent heat storage materials. This work examines the ability of commercially available plasma spray coatings to serve as protective barriers with these alloys, while highlighting mechanistic insights into materials for latent heat storage systems. Computed tomography was leveraged as a rapid screening tool to assess the presence of localized attack in tested coatings.

  12. Novel functional materials from renewable lipids: Amphiphilic antimicrobial polymers and latent heat thermal energy storage

    NASA Astrophysics Data System (ADS)

    Floros, Michael Christopher

    Vegetable oils represent an ideal and renewable feedstock for the synthesis of a variety of functional materials. However, without financial incentive or unique applications motivating a switch, commercial products continue to be manufactured from petrochemical resources. Two different families of high value, functional materials synthesized from vegetable oils were studied. These materials demonstrate superior and unique performance to comparable petrochemical analogues currently on the market. In the first approach, 3 amphiphilic thermoplastic polytriazoles with differing lipophilic segment lengths were synthesized in a polymerization process without solvents or catalysts. Investigation of monomer structure influence on the resultant functional behaviour of these polymers found distinctive odd/even behaviour reliant on the number of carbon atoms in the monomers. Higher concentrations of triazole groups, due to shorter CH2 chains in the monomeric dialkynes, resulted in more brittle polymers, displaying higher tensile strengths but reduced elongation to break characteristics. These polymers had similar properties to commercial petroleum derived thermoplastics. One polymer demonstrated self-assembled surface microstructuring, and displayed hydrophobic properties. Antimicrobial efficacy of the polymers were tested by applying concentrated bacterial solutions to the surfaces, and near complete inhibition was demonstrated after 4 hours. Scanning electron microscope images of killed bacteria showed extensive membrane damage, consistent with the observed impact of other amphiphilic compounds in literature. These polytriazoles are suited for applications in medical devices and implants, where major concerns over antibiotic resistance are prevalent. In the second approach, a series of symmetric, saturated diester phase change materials (PCMs) were also synthesized with superior latent heat values compared to commercial petrochemical analogues. These diesters exhibit

  13. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.; Mathur, A. K.

    1980-01-01

    Five tasks to select, design, fabricate, test and evaluate candidate active heat exchanger modules for future applications to solar and conventional utility power plants were discussed. Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion phase change materials (PCMs) in the temperature range of 250 to 350 C. Twenty-six heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were selected for small-scale experimentation: a coated tube and shell heat exchanger and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over 50 candidate inorganic salt mixtures. Based on a salt screening process, eight major component salts were selected initially for further evaluation. The most attractive major components in the temperature range of 250 to 350 C appeared to be NaNO3, NaNO2, and NaOH. Sketches of the two active heat exchange concepts selected for test are given.

  14. Active heat exchange system development for latent heat thermal energy storage

    NASA Astrophysics Data System (ADS)

    Lefrois, R. T.; Mathur, A. K.

    1980-04-01

    Five tasks to select, design, fabricate, test and evaluate candidate active heat exchanger modules for future applications to solar and conventional utility power plants were discussed. Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion phase change materials (PCMs) in the temperature range of 250 to 350 C. Twenty-six heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were selected for small-scale experimentation: a coated tube and shell heat exchanger and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over 50 candidate inorganic salt mixtures. Based on a salt screening process, eight major component salts were selected initially for further evaluation. The most attractive major components in the temperature range of 250 to 350 C appeared to be NaNO3, NaNO2, and NaOH. Sketches of the two active heat exchange concepts selected for test are given.

  15. A Numerical Study of a Double Pipe Latent Heat Thermal Energy Storage System

    NASA Astrophysics Data System (ADS)

    Tabassum, Tonny

    Solar energy is an intermittent supply source of energy. To efficiently utilize this free renewable energy source some form of thermal energy storage devices are necessary. Phase change materials (PCMs), because of their high energy density storage capacity and near isothermal phase change characteristics, have proven to be promising candidates for latent heat thermal energy storage (LHTES) devices. Among the various LHTES devices for low temperature residential heating and cooling applications, the shell-and-tube type heat exchanging devices are the most simple to operate and can be easily fabricated. This work numerically investigates the buoyancy driven heat transfer process during melting (charging) of a commercial paraffin wax as PCM filling the annulus of a horizontal double pipe heat exchanger. The heated working fluid (water) is passing through the central tube of the annulus at a sufficiently high flow-rate and thereby maintaining an almost isothermal wall temperature at the inner pipe which is higher than the melting temperature of the PCM. The transient, two-dimensional coupled laminar momentum and energy equations for the model are suitably non-dimensionalized and are solved numerically using the enthalpy-porosity approach. Time-wise evolutions of the flow patterns and temperature distributions are presented through velocity vector fields and isotherm plots. In this study, two types of PCM filled annuli, a plain annulus and a strategically placed longitudinal finned annulus, are studied. The total energy stored, the total liquid fraction and the energy efficiency at different melting times are evaluated for three different operating conditions and the results are compared between the plain and finned annuli. The present study will provide guidelines for system thermal performance and design optimization of the shell-and-tube LHTES devices. .

  16. Study of the Melting Latent Heat of Semicrystalline PVDF applied to High Gamma Dose Dosimetry

    SciTech Connect

    Batista, Adriana S.M.; Gual, Maritza R.; Faria, Luiz O.; Lima, Claubia P.B.

    2015-07-01

    Poly(vinylidene fluoride) homopolymers [PVDF] homopolymers were irradiated with gamma doses ranging from 0.5 to 2.75 MGy. Differential scanning calorimetry (DSC) and FTIR spectrometry were used in order to study the effects of gamma radiation in the amorphous and crystalline polymer structures. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. The melting latent heat (LM) measured by DSC was used to construct an unambiguous relationship with the delivered dose. Regression analyses revealed that the best mathematical function that fits the experimental calibration curve is a 4-degree polynomial function, with an adjusted Rsquare of 0.99817. (authors)

  17. The sensitivity of latent heat flux to the air humidity approximations used in ocean circulation models

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, Pearn P.

    1990-01-01

    In deriving the surface latent heat flux with the bulk formula for the thermal forcing of some ocean circulation models, two approximations are commonly made to bypass the use of atmospheric humidity in the formula. The first assumes a constant relative humidity, and the second supposes that the sea-air humidity difference varies linearly with the saturation humidity at sea surface temperature. Using climatological fields derived from the Marine Deck and long time series from ocean weather stations, the errors introduced by these two assumptions are examined. It is shown that the errors reach above 100 W/sq m over western boundary currents and 50 W/sq m over the tropical ocean. The two approximations also introduce erroneous seasonal and spatial variabilities with magnitudes over 50 percent of the observed variabilities.

  18. Development of latent fingerprints on thermal paper by the controlled application of heat.

    PubMed

    Bond, John W

    2013-05-01

    Apparatus to produce a spatially and temporally uniform heat source is described and this is used to visualize latent fingerprints deposited onto thermal paper by raising the temperature of the paper. Results show an improvement over previous research when fingerprint deposits are aged or the developed fingerprints faint; visualization being enhanced by the use of a blue LED light source of 465 nm peak wavelength. An investigation of the components in fingerprint sweat likely to affect the solubility and hence color change of the dye present in the thermal paper has shown that polar protic solvents able to donate a proton are favored and a polar amino acid found commonly in eccrine fingerprint sweat (lysine) has been shown able to produce the desired color change. Aged fingerprint deposits on thermal paper from a variety of sources up to 4 years old have been visualized with this technique.

  19. Dynamical response of nanostructures and Joule heat release.

    PubMed

    Gurevich, V L; Kozub, V I; Muradov, M I

    2011-10-12

    We consider Joule heat release in a quantum wire joining two classical reservoirs under the action of a nonstationary periodic electric field. The rate of heat generation and its spatial distribution is discussed. The heat is spread over the lengths of electron mean free paths in the reservoirs. We find that the total rates of heat generation in both reservoirs that are joined by the nanostructure are the same.

  20. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.

    1980-01-01

    Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion Phase Change Materials (PCM's) in the temperature range of 250 C to 350 C for solar and conventional power plant applications. Over 24 heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were chosen for small-scale experimentation: a coated tube and shell that exchanger, and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over fifty inorganic salt mixtures investigated. Preliminary experiments with various tube coatings indicated that a nickel or chrome plating of Teflon or Ryton coating had promise of being successful. An electroless nickel plating was selected for further testing. A series of tests with nickel-plated heat transfer tubes showed that the solidifying sodium nitrate adhered to the tubes and the experiment failed to meet the required discharge heat transfer rate of 10 kW(t). Testing of the reflux boiler is under way.

  1. Steady-state performance characteristics of latent heat TES/heat pump systems

    NASA Astrophysics Data System (ADS)

    Sigmon, T. W.

    1982-03-01

    Two projects are currently being completed that wholly or in part address various technical issues involved in the implementation of heat pump systems combined with thermal energy storage (TES). The first of these involves the determination of steady state performance characteristics for six generic TES/heat pump configurations and the comparison of the operational performance of these systems with other space heating and cooling TES technologies. Of these latter systems four are commercial or near commerical air conditioner or heat pump coupled TES systems. Steady state performance has been established for all systems. Operational performance and system life cycle cost has been determined for the six generic designs for a limited set of application conditions. The intent of the second project is to establish a reliable method of estimating seasonal energy use by TES/heat pump systems, to utilize this methodology to evaluate a large number of possible system designs, identify a small number of systems that merit more detailed analysis, and, to the extent possible, conduct these detailed studies.

  2. Active heat exchange system development for latent heat thermal energy storage

    NASA Astrophysics Data System (ADS)

    Lefrois, R. T.

    1980-03-01

    Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion Phase Change Materials (PCM's) in the temperature range of 250 C to 350 C for solar and conventional power plant applications. Over 24 heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were chosen for small-scale experimentation: a coated tube and shell that exchanger, and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over fifty inorganic salt mixtures investigated. Preliminary experiments with various tube coatings indicated that a nickel or chrome plating of Teflon or Ryton coating had promise of being successful. An electroless nickel plating was selected for further testing. A series of tests with nickel-plated heat transfer tubes showed that the solidifying sodium nitrate adhered to the tubes and the experiment failed to meet the required discharge heat transfer rate of 10 kW(t). Testing of the reflux boiler is under way.

  3. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 1; Method and Uncertainties

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Petty, Grant W.; Tao, Wei-Kuo; Bell, Thomas L.; Braun, Scott A.; Wang, Yansen; Lang, Stephen E.; Johnson, Daniel E.

    2004-01-01

    A revised Bayesian algorithm for estimating surface rain rate, convective rain proportion, and latent heating/drying profiles from satellite-borne passive microwave radiometer observations over ocean backgrounds is described. The algorithm searches a large database of cloud-radiative model simulations to find cloud profiles that are radiatively consistent with a given set of microwave radiance measurements. The properties of these radiatively consistent profiles are then composited to obtain best estimates of the observed properties. The revised algorithm is supported by an expanded and more physically consistent database of cloud-radiative model simulations. The algorithm also features a better quantification of the convective and non-convective contributions to total rainfall, a new geographic database, and an improved representation of background radiances in rain-free regions. Bias and random error estimates are derived from applications of the algorithm to synthetic radiance data, based upon a subset of cloud resolving model simulations, and from the Bayesian formulation itself. Synthetic rain rate and latent heating estimates exhibit a trend of high (low) bias for low (high) retrieved values. The Bayesian estimates of random error are propagated to represent errors at coarser time and space resolutions, based upon applications of the algorithm to TRMM Microwave Imager (TMI) data. Errors in instantaneous rain rate estimates at 0.5 deg resolution range from approximately 50% at 1 mm/h to 20% at 14 mm/h. These errors represent about 70-90% of the mean random deviation between collocated passive microwave and spaceborne radar rain rate estimates. The cumulative algorithm error in TMI estimates at monthly, 2.5 deg resolution is relatively small (less than 6% at 5 mm/day) compared to the random error due to infrequent satellite temporal sampling (8-35% at the same rain rate).

  4. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Alario, J.; Kosson, R.; Haslett, R.

    1980-01-01

    Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application (300 MW sub t storage for 6 hours). Two concepts were selected for hardware development: (1) a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and (2) a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which was nickel plated to decrease adhesion forces. In addition to improving performance by providing a nearly constant transfer rate during discharge, these active heat exchanger concepts were estimated to cost at least 25% less than the passive tube-shell design.

  5. The impact of vertical measurement depth on the information content of soil moisture for latent heat flux estimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using ground-based soil moisture and latent/sensible heat fluxes observations acquired from the Ameriflux Network, we calculate the mutual information (MI) content between multiple soil moisture variables and evaporative fraction (EF) to examine the existence of information in vertically-integrated ...

  6. An Empirical Orthogonal Function-Based Algorithm for Estimating Terrestrial Latent Heat Flux from Eddy Covariance, Meteorological and Satellite Observations

    PubMed Central

    Feng, Fei; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Chen, Jiquan; Zhao, Xiang; Jia, Kun; Pintér, Krisztina; McCaughey, J. Harry

    2016-01-01

    Accurate estimation of latent heat flux (LE) based on remote sensing data is critical in characterizing terrestrial ecosystems and modeling land surface processes. Many LE products were released during the past few decades, but their quality might not meet the requirements in terms of data consistency and estimation accuracy. Merging multiple algorithms could be an effective way to improve the quality of existing LE products. In this paper, we present a data integration method based on modified empirical orthogonal function (EOF) analysis to integrate the Moderate Resolution Imaging Spectroradiometer (MODIS) LE product (MOD16) and the Priestley-Taylor LE algorithm of Jet Propulsion Laboratory (PT-JPL) estimate. Twenty-two eddy covariance (EC) sites with LE observation were chosen to evaluate our algorithm, showing that the proposed EOF fusion method was capable of integrating the two satellite data sets with improved consistency and reduced uncertainties. Further efforts were needed to evaluate and improve the proposed algorithm at larger spatial scales and time periods, and over different land cover types. PMID:27472383

  7. Characterization of Turbulent Latent and Sensible Heat Flux Exchange Between the Atmosphere and Ocean in MERRA

    NASA Technical Reports Server (NTRS)

    Roberts, J. Brent; Robertson, Franklin R.; Clayson, Carol Anne; Bosilovich, Michael G.

    2012-01-01

    Turbulent fluxes of heat and moisture across the atmosphere-ocean interface are fundamental components of the Earth s energy and water balance. Characterizing both the spatiotemporal variability and the fidelity of these exchanges of heat and moisture is critical to understanding the global water and energy cycle variations, quantifying atmosphere-ocean feedbacks, and improving model predictability. This study examines the veracity of the recently completed NASA Modern-Era Retrospective analysis for Research and Applications (MERRA) product with respect to its representation of the surface turbulent heat fluxes. A validation of MERRA turbulent heat fluxes and near-surface bulk variables at local, high-resolution space and time scales is achieved by making comparisons to a large suite of direct observations. Both in situ and satellite-observed gridded surface heat flux estimates are employed to investigate the spatial and temporal variability of the surface fluxes with respect to their annual mean climatologies, their seasonal covariability of near-surface bulk parameters, and their representation of extremes. The impact of data assimilation on the near-surface parameters is assessed through evaluation of incremental analysis update tendencies produced by the assimilation procedure. It is found that MERRA turbulent surface heat fluxes are relatively accurate for typical conditions but have systematically weak vertical gradients in moisture and temperature and have a weaker covariability between the near-surface gradients and wind speed than found in observations. This results in an underestimate of the surface latent and sensible heat fluxes over the western boundary current and storm track regions. The assimilation of observations mostly acts to bring MERRA closer to observational products by increasing moisture and temperature near the surface and decreasing the near-surface wind speeds. The major patterns of spatial and temporal variability of the turbulent heat

  8. Characterization of Turbulent Latent and Sensible Heat Flux Exchange Between the Atmosphere and Ocean in MERRA

    NASA Technical Reports Server (NTRS)

    Robert, J. Brent; Robertson, Franklin R.; Clayson, Carol Anne; Bosilovich, Michael G.

    2012-01-01

    Turbulent fluxes of heat and moisture across the atmosphere-ocean interface are fundamental components of the Earth's energy and water balance. Characterizing both the spatiotemporal variability and the fidelity of these exchanges of heat and moisture is critical to understanding the global water and energy cycle variations, quantifying atmosphere-ocean feedbacks, and improving model predictability. This study examines the veracity of the recently completed NASA Modern-Era Retrospective analysis for Research and Applications (MERRA) product with respect to its representation of the surface turbulent heat fluxes. A validation of MERRA turbulent heat fluxes and near-surface bulk variables at local, high-resolution space and time scales is achieved by making comparisons to a large suite of direct observations. Both in situ and satellite-observed gridded surface heat flux estimates are employed to investigate the spatial and temporal variability of the surface fluxes with respect to their annual mean climatologies, their seasonal covariability of near-surface bulk parameters, and their representation of extremes. The impact of data assimilation on the near-surface parameters is assessed through evaluation of incremental analysis update tendencies produced by the assimilation procedure. It is found that MERRA turbulent surface heat fluxes are relatively accurate for typical conditions but have systematically weak vertical gradients in moisture and temperature and have a weaker covariability between the near-surface gradients and wind speed than found in observations. This results in an underestimate of the surface latent and sensible heat fluxes over the western boundary current and storm track regions. The assimilation of observations mostly acts to bring MERRA closer to observational products by increasing moisture and temperature near the surface and decreasing the near-surface wind speeds. The major patterns of spatial and temporal variability of the turbulent heat

  9. Numerical treatment of nonlinear latent heat boundary conditions at moving interfaces in genuine two dimensional solidification problems

    NASA Technical Reports Server (NTRS)

    Beckett, P. M.

    1981-01-01

    The proposed method for the treatment of two dimensional solidification problems is based on quasilinearization of the transformed heat conduction equation and latent heat condition at the interface and an iterative sequence in which these are solved simultaneously. Modern algorithms for solving such sparse systems mean that most of the storage advantage of other methods are reduced and the speed of solution can be improved.

  10. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Alario, J.; Haslett, R.

    1980-01-01

    Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application. Two concepts selected for hardware development are a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which has been nickel plated to decrease adhesion forces. Suitable phase change material (PCM) storage media with melting points in the temperature range of interest (250 C to 400 C) were investigated. The specific salt recommended for laboratory tests was a chloride eutectic (20.5KCl-24/5 NaCl-55.0MgCl 2% by wt.), with a nominal melting point of 385 C.

  11. Active heat exchange system development for latent heat thermal energy storage

    NASA Astrophysics Data System (ADS)

    Alario, J.; Haslett, R.

    1980-03-01

    Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application. Two concepts selected for hardware development are a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which has been nickel plated to decrease adhesion forces. Suitable phase change material (PCM) storage media with melting points in the temperature range of interest (250 C to 400 C) were investigated. The specific salt recommended for laboratory tests was a chloride eutectic (20.5KCl-24/5 NaCl-55.0MgCl 2% by wt.), with a nominal melting point of 385 C.

  12. Expression and release of the latent transforming growth factor beta binding protein by hepatocytes from rat liver.

    PubMed

    Roth, S; Schurek, J; Gressner, A M

    1997-06-01

    In very recent studies it was established that transforming growth factor beta (TGF-beta), likely to be the most relevant fibrogenic cytokine and regulator of cell proliferation, differentiation, and matrix metabolism, is expressed by hepatocytes (parenchymal cell [PC]) and secreted from cultured PC in a latent form incapable of receptor binding. The structural composition of the latent TGF-beta complex secreted by cultured PC is unknown. In some TGF-beta expressing cell types this cytokine is released as a large molecular weight complex containing in addition to the TGF-beta latency associated peptide (LAP) a disulfide bonded latent TGF-beta binding protein (LTBP), of which the existence and function in liver is hitherto unknown. This study is directed to the identification of LTBP expression in rat PC. Cells were isolated from rat liver with the collagenase method and analyzed for LTBP before and during culture under standard conditions using alkaline phosphatase anti-alkaline phosphatase (APAAP) immunostainings, metabolic labeling, messenger RNA (mRNA) detection (reverse-transcription polymerase chain reaction [RT-PCR]) and sequencing, and immunoblotting of gel chromatographically separated cell extracts and conditioned media, respectively. APAAP immunostainings applying a specific polyclonal LTBP-antiserum (ab 39) indicated expression of LTBP in PC of liver in situ and freshly isolated PC but a strong expression in cultured PC. Transcripts of LTBP-1 were detected by RT-PCR and confirmed by sequence analyses. Metabolic labeling of PC with [35S]-Met/Cys followed by immunoprecipitation of cell lysates with LTBP antiserum confirmed the synthesis of the high molecular mass complex of 250 kd containing LTBP with a molecular mass of 160 kd. Latent TGF-beta complexes, associated with LTBP related proteins, could be separated from both extracts and conditioned media of PC by gel filtration chromatography. They confirmed the release of the large latent TGF-beta complex

  13. TRMM Latent Heating Retrieval: Applications and Comparisons with Field Campaigns and Large-Scale Analyses

    SciTech Connect

    Tao, Wei-Kuo; Takayabu, Yukari N.; Lang, Steve; Shige, Shoichi; Olson, William S.; Hou, Arthur; Skofronick-Jackson, Gail; Jiang, Xining; Zhang, Chidong; Lau, William K.; Krishnamurti, T.; Waliser, D.; Grecu, M.; Ciesielski, Paul; Johnson, Richard; Houze, Robert A.; Kakar, R.; Nakamura, K.; Braun, S.; Hagos, Samson M.; Oki, R.; Bhardwaj, A.

    2016-05-05

    Yanai et al. (1973) utilized the meteorological data collected from a sounding network to present a pioneering work on thermodynamic budgets, which are referred to as the apparent heat source (Q1) and apparent moisture sink (Q2). Latent heating (LH) is one of the most dominant terms in Q1. Yanai’s paper motivated the development of satellite-based LH algorithms and provided a theoretical background for imposing large-scale advective forcing into cloud-resolving models (CRMs). These CRM-simulated LH and Q1 data have been used to generate the look-up tables in Tropical Rainfall Measuring Mission (TRMM) LH algorithms. A set of algorithms developed for retrieving LH profiles from TRMM-based rainfall profiles are described and evaluated, including details concerning their intrinsic space-time resolutions. Included in the paper are results from a variety of validation analyses that define the uncertainty of the LH profile estimates. Also, examples of how TRMM-retrieved LH profiles have been used to understand the lifecycle of the MJO and improve the predictions of global weather and climate models as well as comparisons with large-scale analyses are provided. Areas for further improvement of the TRMM products are discussed.

  14. Aircraft- and tower-based fluxes of carbon dioxide, latent, and sensible heat

    NASA Technical Reports Server (NTRS)

    Desjardins, R. L.; Hart, R. L.; Macpherson, J. I.; Schuepp, P. H.; Verma, S. B.

    1992-01-01

    Fluxes of carbon dioxide, water vapor, and sensible heat obtained over a grassland ecosystem, during the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE), using an aircraft- and two tower-based systems are compared for several days in 1987 and in 1989. The tower-based cospectral estimates of CO2, sensible heat, water vapor, and momentum, expressed as a function of wavenumber K times sampling height z, are relatively similar to the aircraft-based estimates for K x z greater than 0.1. A measurable contribution to the fluxes is observed by tower-based systems at K x z less than 0.01 but not by the aircraft-based system operating at an altitude of approximately 100 m over a 15 x 15 km area. Using all available simultaneous aircraft and tower data, flux estimates by both systems were shown to be highly correlated. As expected from the spatial variations of the greenness index, surface extrapolation of airborne flux estimates tended to lie between those of the two tower sites. The average fluxes obtained, on July 11, 1987, and August 4, 1989, by flying a grid pattern over the FIFE site agreed with the two tower data sets for CO2, but sensible and latent heat were smaller than those obtained by the tower-based systems. However, in general, except for a small underestimation due to the long wavelength contributions and due to flux divergence with height, the differences between the aircraft- and tower-based surface estimates of fluxes appear to be mainly attributable to differences in footprint, that is, differences in the area contributing to the surface flux estimates.

  15. Hanford production reactor heat releases 1951--1971

    SciTech Connect

    Kannberg, L.D.

    1992-04-01

    The purpose of this report is to document and detail the thermal releases from the Hanford nuclear production reactors during the period 1951 through 1971, and to put these releases in historical perspective with respect to changing Columbia River flows and temperatures. This information can also be used as a foundation for further ecological evaluations. When examining Hanford production reactor thermal releases to the Columbia River all related factors affecting the releases and the characteristics of the river should be considered. The major considerations in the present study were the characteristics of the releases themselves (primarily coolant flow rate, temperatures, discharge facilities, period of operation, and level of operation) and the characteristics of the river in that reach (primarily flow rate, temperature and mixing characteristics; the effects of dam construction were also taken into account). In addition, this study addressed ecological effects of thermal releases on aquatic species. Accordingly, this report includes discussion of the reactor cooling system, historical heat releases, thermal mixing and transport studies, hydroelectric power development, and ecologic effects of Hanford production reactor heat releases on salmon and trout. Appendix A contains reactor operating statistics, and Appendix B provide computations of heat added to the Columbia River between Priest Rapids Dam and Richland, Washington.

  16. A Comparison of Latent Heat Fluxes over Global Oceans for Four Flux Products

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.

    2003-01-01

    To improve our understanding of global energy and water cycle variability, and to improve model simulations of climate variations, it is vital to have accurate latent heat fluxes (LHF) over global oceans. Monthly LHF, 10-m wind speed (U10m), 10-m specific humidity (Q10h), and sea-air humidity difference (Qs-Q10m) of GSSTF2 (version 2 Goddard Satellite-based Surface Turbulent Fluxes) over global Oceans during 1992-93 are compared with those of HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP (NCEP/NCAR reanalysis). The mean differences, standard deviations of differences, and temporal correlation of these monthly variables over global Oceans during 1992-93 between GSSTF2 and each of the three datasets are analyzed. The large-scale patterns of the 2yr-mean fields for these variables are similar among these four datasets, but significant quantitative differences are found. The temporal correlation is higher in the northern extratropics than in the south for all variables, with the contrast being especially large for da Silva as a result of more missing ship data in the south. The da Silva has extremely low temporal correlation and large differences with GSSTF2 for all variables in the southern extratropics, indicating that da Silva hardly produces a realistic variability in these variables. The NCEP has extremely low temporal correlation (0.27) and large spatial variations of differences with GSSTF2 for Qs-Q10m in the tropics, which causes the low correlation for LHF. Over the tropics, the HOAPS LHF is significantly smaller than GSSTF2 by approx. 31% (37 W/sq m), whereas the other two datasets are comparable to GSSTF2. This is because the HOAPS has systematically smaller LHF than GSSTF2 in space, while the other two datasets have very large spatial variations of large positive and negative LHF differences with GSSTF2 to cancel and to produce smaller regional-mean differences. Our analyses suggest that the GSSTF2 latent heat flux

  17. Trends and Variations of Ocean Surface Latent Heat Flux: Results from GSSTF2c Data Set

    NASA Technical Reports Server (NTRS)

    Gao, Si; Chiu, Long S.; Shie, Chung-Lin

    2013-01-01

    Trends and variations of Goddard Satellite-based Surface Turbulent Fluxes (GSSTF) version 2c (GSSTF2c) latent heat flux (LHF) are examined. This version of LHF takes account of the correction in Earth incidence angle. The trend of global mean LHF for GSSTF2c is much reduced relative to GSSTF version 2b Set 1 and Set 2 for the same period 1988-2008. Temporal increase of GSSTF2c LHF in the two decades is 11.0%, in which 3.1%, 5.8%, and 2.1% are attributed to the increase in wind, the increase in sea surface saturated air humidity, and the decrease in near-surface air humidity, respectively. The first empirical orthogonal function of LHF is a conventional El Nino Southern Oscillation (ENSO) mode. However, the trends in LHF are independent of conventional ENSO phenomena. After removing ENSO signal, the pattern of LHF trends is primarily determined by the pattern of air-sea humidity difference trends.

  18. A comparison of small and larger mesoscale latent heat and radiative fluxes: December 6 case study

    NASA Technical Reports Server (NTRS)

    Gultepe, I.; Starr, David; Heymsfield, A. J.

    1993-01-01

    Because of the small amounts of water vapor, the potential for rapid changes, and the very cold temperatures in the upper troposphere, moisture measuring instruments face several problems related to calibration and response. Calculations of eddy moisture fluxes are, therefore, subject to significant uncertainty. The purpose of this study is to examine the importance of latent heat (moisture) fluxes due to small and larger mesoscale circulations in comparison to radiative fluxes within cirrus. Scale separation is made at about 1 km because of significant changes in the structures within cirrus. Only observations at warmer than -40 C are used in this study. The EG&G hygrometer that is used for measuring dewpoint temperature (Td) is believed to be fairly accurate down to -40 C. On the other hand, Lyman-Alpha (L-alpha) hygrometer measurements of moisture may include large drift errors. In order to compensate for these drift errors, the L-alpha hygrometer is often calibrated against the EG&G hygrometer. However, large errors ensue for Td measurements at temperatures less than -40 C. The cryogenic hygrometer frost point measurements may be used to calibrate L-alpha measurements at temperatures less than -40 C. In this study, however, measurements obtained by EG&G hygrometer and L-alpha measurements are used for the flux calculations.

  19. Advanced latent heat storage media for high-temperature industrial applications

    NASA Astrophysics Data System (ADS)

    Olszewski, M.

    1984-03-01

    Several advanced thermal energy storage (TES) media are being developed for high temperature industrial applications. One of the concepts involves a composite medium consisting of a phase-change carbonate salt supported and immobilized within a submicro sized capillary structure of a particulate ceramic matrix or porous sintered ceramic. Immobilization of the molten salt within the ceramic structure permits operation of the composite pellets, bricks, or other shapes in direct contact with compatible fluids. Energy storage occurs in both sensible and latent forms with the composite providing higher energy storage densities than standard sensible heat storage systems. The second concept centers on the development of a self-encapsulating metallic eutectic. This work focuses on metallic eutectics containing silicon. Starting with a silicon-rich mixture, it is feasible to develop a self-encapsulating pellet by cooling the liquid drops at a controlled rate. A solid of nearly pure silicon will form on the exterior of the pellet leaving a eutectic, phase change media in the interior. The concept are described and information concerning current development activities is presented.

  20. Seasonal effects of irrigation on land-atmosphere latent heat, sensible heat, and carbon fluxes in semiarid basin

    NASA Astrophysics Data System (ADS)

    Zeng, Yujin; Xie, Zhenghui; Liu, Shuang

    2017-02-01

    Irrigation, which constitutes ˜ 70 % of the total amount of freshwater consumed by the human population, is significantly impacting land-atmosphere fluxes. In this study, using the improved Community Land Model version 4.5 (CLM4.5) with an active crop model, two high-resolution (˜ 1 km) simulations investigating the effects of irrigation on latent heat (LH), sensible heat (SH), and carbon fluxes (or net ecosystem exchange, NEE) from land to atmosphere in the Heihe River basin in northwestern China were conducted using a high-quality irrigation dataset compiled from 1981 to 2013. The model output and measurements from remote sensing demonstrated the capacity of the developed models to reproduce ecological and hydrological processes. The results revealed that the effects of irrigation on LH and SH are strongest during summer, with a LH increase of ˜ 100 W m-2 and a SH decrease of ˜ 60 W m-2 over intensely irrigated areas. However, the reactions are much weaker during spring and autumn when there is much less irrigation. When the irrigation rate is below 5 mm day-1, the LH generally increases, whereas the SH decreases with growing irrigation rates. However, when the irrigation threshold is in excess of 5 mm day-1, there is no accrued effect of irrigation on the LH and SH. Irrigation produces opposite effects to the NEE during spring and summer. During the spring, irrigation yields more discharged carbon from the land to the atmosphere, increasing the NEE value by 0.4-0.8 gC m-2 day-1, while the summer irrigation favors crop fixing of carbon from atmospheric CO2, decreasing the NEE value by ˜ 0.8 gC m-2 day-1. The repercussions of irrigation on land-atmosphere fluxes are not solely linked to the irrigation amount, and other parameters (especially the temperature) also control the effects of irrigation on LH, SH, and NEE.

  1. Melting and solidification characteristics of a mixture of two types of latent heat storage material in a vessel

    NASA Astrophysics Data System (ADS)

    Yu, JikSu; Horibe, Akihiko; Haruki, Naoto; Machida, Akito; Kato, Masashi

    2016-11-01

    In this study, we investigated the fundamental melting and solidification characteristics of mannitol, erythritol, and their mixture (70 % by mass mannitol: 30 % by mass erythritol) as potential phase-change materials (PCMs) for latent heat thermal energy storage systems, specifically those pertaining to industrial waste heat, having temperatures in the range of 100-250 °C. The melting point of erythritol and mannitol, the melting peak temperature of their mixture, and latent heat were measured using differential scanning calorimetry. The thermal performance of the mannitol mixture was determined during melting and solidification processes, using a heat storage vessel with a pipe heat exchanger. Our results indicated phase-change (fusion) temperatures of 160 °C for mannitol and 113 and 150 °C for the mannitol mixture. Nondimensional correlation equations of the average heat transfer during the solidification process, as well as the temperature and velocity efficiencies of flowing silicon oil in the pipe and the phase-change material (PCM), were derived using several nondimensional parameters.

  2. The Estimation of Surface Latent Heat Flux over the Ocean and its Relationship to Marine Atmospheric Boundary Layer (MABL) Structure

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Schwemmer, Geary K.; Vandemark, Doug; Evans, Keith; Miller, David O.; Demoz, Belay B.; Starr, David OC. (Technical Monitor)

    2001-01-01

    A new technique combining active and passive remote sensing instruments for the estimation of surface latent heat flux over the ocean is presented. This synergistic method utilizes aerosol lidar backscatter data, multi-channel infrared radiometer data, and microwave scatterometer data acquired onboard the NASA P-313 research aircraft during an extended field campaign over the Atlantic ocean in support of the Lidar In-space Technology Experiment (LITE) in September of 1994. The 10 meter wind speed derived from scatterometers and lidar-radiometer inferred near-surface moisture are used to obtain an estimate of the surface flux of moisture via a bulk aerodynamic formula. The results are compared with the Special Sensor Microwave Imager (SSM/I) daily average latent heat flux and show reasonable agreement. However, the SSM/I values are biased low by about 15 W/sq m. In addition, the Marine Atmospheric Boundary Layer (MABL) height, entrainment zone thickness and integrated lidar backscatter intensity are computed from the lidar data and compared with the magnitude of the surface fluxes. The results show that the surface latent heat flux is most strongly correlated with entrainment zone depth, MABL height and the integrated MABL lidar backscatter, with corresponding correlation coefficients of 0.39, 0.43 and 0.71, respectively.

  3. The Estimation Surface Latent Heat Flux Over the Ocean and its Relationship to Marine Atmospheric Boundary Layer (MABL) Structure

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Schwemmer, Geary K.; Vandemark, Doug; Evans, Keith; Miller, David O.

    1999-01-01

    A new technique combining active and passive remote sensing instruments for the estimation of surface latent heat flux over the ocean is presented. This synergistic method utilizes aerosol lidar backscatter data, multi-channel infrared radiometer data and microwave scatterometer data acquired onboard the NASA P-3B research aircraft during an extended field campaign over the Atlantic ocean in support of the Lidar In-space Technology Experiment (LITE) in September of 1994. The 10 meter wind speed derived from the scatterometers and the lidar-radiometer inferred near-surface moisture are used to obtain an estimate of the surface flux of moisture via bulk aerodynamic formulae. The results are compared with the Special Sensor Microwave Imager (SSM/I) daily average latent heat flux and show reasonable agreement. However, the SSM/I values are biased high by about 30 W/sq m. In addition, the MABL height, entrainment zone thickness and integrated lidar backscatter intensity are computed from the lidar data and compared with the magnitude of the surface fluxes. The results show that the surface latent heat flux is most strongly correlated with entrainment zone top, bottom and the integrated MABL lidar backscatter, with corresponding correlation coefficients of 0.62, 0.67 and 0.61, respectively.

  4. The Estimation of Surface Latent Heat Flux Over the Ocean and its Relationship to Marine Atmospheric Boundary Layer (MABL) Structure

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Miller, David O.; Schwemmer, Geary

    2000-01-01

    A new technique combining active and passive remote sensing instruments for the estimation of surface latent heat flux over the ocean is presented. This synergistic method uses aerosol lidar backscatter data, multi-channel infrared radiometer data and microwave scatterometer data acquired onboard the NASA P-3B research aircraft during an extended field campaign over the Atlantic ocean in support of the Lidar In-space Technology Experiment (LITE) in September of 1994. The 10 meter wind speed derived from the scatterometers and the lidar-radiometer inferred near-surface moisture are used to obtain an estimate of the surface flux of moisture via bulk aerodynamic formulae. The results are compared with the Special Sensor Microwave Imager (SSM/I) daily average latent heat flux and show reasonable agreement with an rms error and bias of about 50 and 25 W per square meters, respectively. In addition, the MABL height, entrainment zone thickness and integrated lidar backscatter intensity are computed from the lidar data and compared with the magnitude of the surface fluxes. The results show that the surface latent heat flux is most strongly correlated with entrainment zone top, bottom and the integrated MABL lidar backscatter, with corresponding correlation coefficients of 0.62, 0.67 and 0.61, respectively.

  5. Development of approximate method to analyze the characteristics of latent heat thermal energy storage system

    SciTech Connect

    Saitoh, T.S.; Hoshi, Akira

    1999-07-01

    Third Conference of the Parties to the U.N. Framework Convention on Climate Change (COP3) held in last December in Kyoto urged the industrialized nation to reduce carbon dioxide (CO{sub 2}) emissions by 5.2 percent (on the average) below 1990 level until the period between 2008 and 2012 (Kyoto protocol). This implies that even for the most advanced countries like the US, Japan, and EU implementation of drastic policies and overcoming many barriers in market should be necessary. One idea which leads to a path of low carbon intensity is to adopt an energy storage concept. One of the reasons that the efficiency of the conventional energy systems has been relatively low is ascribed to lacking of energy storage subsystem. Most of the past energy systems, for example, air-conditioning system, do not have energy storage part and the system usually operates with low energy efficiency. Firstly, the effect of reducing CO{sub 2} emissions was also examined if the LHTES subsystems were incorporated in all the residential and building air-conditioning systems. Another field of application of the LHTES is of course transportation. Future vehicle will be electric or hybrid vehicle. However, these vehicles will need considerable energy for air-conditioning. The LHTES system will provide enough energy for this purpose by storing nighttime electricity or rejected heat from the radiator or motor. Melting and solidification of phase change material (PCM) in a capsule is of practical importance in latent heat thermal energy storage (LHTES) systems which are considered to be very promising to reduce a peak demand of electricity in the summer season and also reduce carbon dioxide (CO{sub 2}) emissions. Two melting modes are involved in melting in capsules. One is close-contact melting between the solid bulk and the capsule wall, and another is natural convection melting in the liquid (melt) region. Close-contact melting processes for a single enclosure have been solved using several

  6. A preliminary evaluation of surface latent heat flux as an earthquake precursor

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhao, J.; Wang, W.; Ren, H.; Chen, L.; Yan, G.

    2013-06-01

    The relationship between variations in surface latent heat flux (SLHF) and marine earthquakes has been a popular subject of recent seismological studies. So far, there are two key problems: how to identify the abnormal SLHF variations from complicated background signals, and how to ensure that the anomaly results from earthquake. In this paper, we proposed four adjustable parameters for identification, classified the relationship and analyze SLHF changes several months before six marine earthquakes by employing daily SLHF data. Besides, we also quantitatively evaluate the long-term relationship between earthquakes and SLHF anomalies for the six study areas over a 20 yr period preceding each earthquake. The results suggest: (1) before the South Sandwich Islands, Papua, Samoa and Haiti earthquakes, the SLHF variations above their individual background levels have relatively low amplitudes and are difficult to be considered as precursory anomalies; (2) after removing the clustering effect, most of the anomalies prior to these six earthquakes are not temporally related to any earthquake in each study area in time sequence; (3) for each case, apart from Haiti, more than half of studied earthquakes which were moderate even devastating earthquakes (larger than Mw = 5.3) had no precursory variations in SLHF; and (4) the correlation between SLHF and seismic activity depends largely on data accuracy and parameter settings. Before any application of SLHF data on earthquake prediction, we suggest that anomaly-identifying standards should be established based on long-term regional analysis to eliminate subjectivity. Furthermore, other factors which may result in SLHF variations also should be carefully considered.

  7. A preliminary evaluation of surface latent heat flux as an earthquake precursor

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhao, J.; Wang, W.; Ren, H.; Chen, L.; Yan, G.

    2013-10-01

    The relationship between variations in surface latent heat flux (SLHF) and marine earthquakes has been a popular subject of recent seismological studies. So far, there are two key problems: how to identify the abnormal SLHF variations from complicated background signals, and how to ensure that the anomaly results from an earthquake. In this paper, we proposed four adjustable parameters for identification, classified the relationship and analyzed SLHF changes several months before six marine earthquakes by employing daily SLHF data. Additionally, we also quantitatively evaluate the long-term relationship between earthquakes and SLHF anomalies for the six study areas over a 20 yr period preceding each earthquake. The results suggest the following: (1) before the South Sandwich Islands, Papua, Samoa and Haiti earthquakes, the SLHF variations above their individual background levels have relatively low amplitudes and are difficult to be considered as precursory anomalies; (2) after removing the clustering effect, most of the anomalies prior to these six earthquakes are not temporally related to any earthquake in each study area in time sequence; (3) for each case, apart from Haiti, more than half of the studied earthquakes, which were moderate and even devastating earthquakes (larger than Mw = 5.3), had no precursory variations in SLHF; and (4) the correlation between SLHF and seismic activity depends largely on data accuracy and parameter settings. Before any application of SLHF data on earthquake prediction, we suggest that anomaly-identifying standards should be established based on long-term regional analysis to eliminate subjectivity. Furthermore, other factors that may result in SLHF variations should also be carefully considered.

  8. Surface renewal performance to independently estimate sensible and latent heat fluxes in heterogeneous crop surfaces

    NASA Astrophysics Data System (ADS)

    Suvočarev, K.; Shapland, T. M.; Snyder, R. L.; Martínez-Cob, A.

    2014-02-01

    Surface renewal (SR) analysis is an interesting alternative to eddy covariance (EC) flux measurements. We have applied two recent SR approaches, with different theoretical background, that from Castellví (2004), SRCas, and that from Shapland et al. (2012a,b), SRShap. We have applied both models for sensible (H) and latent (LE) heat flux estimation over heterogeneous crop surfaces. For this, EC equipments, including a sonic anemometer CSAT3 and a krypton hygrometer KH20, were located in two zones of drip irrigated orchards of late and early maturing peaches. The measurement period was June-September 2009. The SRCas is based on similarity concepts for independent estimation of the calibration factor (α), which varies with respect to the atmospheric stability. The SRShap is based on analysis of different ramp dimensions, separating the ones that are flux-bearing from the others that are isotropic. According to the results obtained here, there was a high agreement between the 30-min turbulent fluxes independently derived by EC and SRCas. The SRShap agreement with EC was slightly lower. Estimation of fluxes determined by SRCas resulted in higher values (around 11% for LE) with respect to EC, similarly to previously published works over homogeneous canopies. In terms of evapotranspiration, the root mean square error (RMSE) between EC and SR was only 0.07 mm h-1 (for SRCas) and 0.11 mm h-1 (for SRShap) for both measuring spots. According to the energy balance closure, the SRCas method was as reliable as the EC in estimating the turbulent fluxes related to irrigated agriculture and watershed distribution management, even when applied in heterogeneous cropping systems.

  9. Modeling Subducting Slabs: Structural Variations due to Thermal Models, Latent Heat Feedback, and Thermal Parameter

    NASA Astrophysics Data System (ADS)

    Marton, F. C.

    2001-12-01

    The thermal, mineralogical, and buoyancy structures of thermal-kinetic models of subducting slabs are highly dependent upon a number of parameters, especially if the metastable persistence of olivine in the transition zone is investigated. The choice of starting thermal model for the lithosphere, whether a cooling halfspace (HS) or plate model, can have a significant effect, resulting in metastable wedges of olivine that differ in size by up to two to three times for high values of the thermal parameter (ǎrphi). Moreover, as ǎrphi is the product of the age of the lithosphere at the trench, convergence rate, and dip angle, slabs with similar ǎrphis can show great variations in structures as these constituents change. This is especially true for old lithosphere, as the lithosphere continually cools and thickens with age for HS models, but plate models, with parameters from Parson and Sclater [1977] (PS) or Stein and Stein [1992] (GDH1), achieve a thermal steady-state and constant thickness in about 70 My. In addition, the latent heats (q) of the phase transformations of the Mg2SiO4 polymorphs can also have significant effects in the slabs. Including q feedback in models raises the temperature and reduces the extent of metastable olivine, causing the sizes of the metastable wedges to vary by factors of up to two times. The effects of the choice of thermal model, inclusion and non-inclusion of q feedback, and variations in the constituents of ǎrphi are investigated for several model slabs.

  10. Coupled fvGCM-GCE Modeling System, TRMM Latent Heating and Cloud Library

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2004-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to imiprove the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. A seed fund is available at NASA Goddard to build a MMF based on the 2D GCE model and the Goddard finite volume general circulation model (fvGCM). A prototype MMF will be developed by the end of 2004 and production runs will be conducted at the beginning of 2005. The purpose of this proposal is to augment the current Goddard MMF and other cloud modeling activities. I this talk, I will present: (1) A summary of the second Cloud Modeling Workshop took place at NASA Goddard, (2) A summary of the third TRMM Latent Heating Workshop took place at Nara Japan, (3) A brief discussion on the Goddard research plan of using Weather Research Forecast (WRF) model, and (4) A brief discussion on the GCE model on developing a global cloud simulator.

  11. Coupled fvGCM-GCE Modeling System: TRMM Latent Heating and Cloud Library

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2005-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. A seed fund is available at NASA Goddard to build a MMF based on the 2D GCE model and the Goddard finite volume general circulation model (fvGCM). A prototype MMF will be developed by the end of 2004 and production runs will be conducted at the beginning of 2005. The purpose of this proposal is to augment the current Goddard MMF and other cloud modeling activities. In this talk, I will present: (1) A summary of the second Cloud Modeling Workshop took place at NASA Goddard, (2) A summary of the third TRMM Latent Heating Workshop took place at Nara Japan, (3) A brief discussion on the GCE model on developing a global cloud simulator.

  12. Assessments of surface latent heat flux associated with the Madden-Julian Oscillation in reanalyses

    NASA Astrophysics Data System (ADS)

    Gao, Yingxia; Hsu, Pang-Chi; Hsu, Huang-Hsiung

    2016-09-01

    To understand the accuracy and uncertainty of surface latent heat flux (LHF) associated with the Madden-Julian Oscillation (MJO), the LHF from each of the six global reanalysis datasets is compared with LHF based on in situ data and the objectively analyzed air-sea flux (OAFlux), in terms of tropical intraseasonal variability. The reanalysis products used in this study include the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-I), the Modern-Era Retrospective Analysis for Research and Applications (MERRA), three generations of reanalysis from the National Center for Environmental Prediction (NCEP R1, R2 and CFSR), and the twentieth century reanalysis (20CR). We find that the intraseasonal LHF of the reanalysis products agrees well with the OAFlux over the tropical oceans in terms of patterns, but there is a significant spread in amplitude among the reanalysis products. Both ERA-I and MERRA show smaller biases in the power spectral analysis, while the other reanalysis products (NCEP R1, NCEP R2, CFSR, and 20CR) tend to overestimate the intraseasonal LHF when compared with the TAO buoy products and OAFlux. The role of anomalous LHF in supporting the MJO convection identified by previous TAO buoy data studies is confirmed by the long-term global reanalyses. The feature of increasing LHF accompanied by growing MJO observed in the recent MJO field campaign in the central Indian Ocean (DYNAMO/CINDY2011) is also well captured by the reanalysis products. Among the reanalysis datasets, MERRA has the smallest bias in temporal variability of LHF during the DYNAMO/CINDY2011 period.

  13. Passive ice freezing-releasing heat pipe. [Patent application

    DOEpatents

    Gorski, A.J.; Schertz, W.W.

    1980-09-29

    A heat pipe device has been developed which permits completely passive ice formation and periodic release of ice without requiring the ambient temperature to rise above the melting point of water. This passive design enables the maximum amount of cooling capacity to be stored in the tank.

  14. Assessment of the performance of the drag and bulk transfer method in estimating sensible and latent heat fluxes in a tropical station

    NASA Astrophysics Data System (ADS)

    Adeniyi, Mojisola Oluwayemisi; Ogunsola, Oluseyi E.

    2012-02-01

    The performance of the general bulk formulation in estimating sensible heat flux at Nigerian Micrometeorological Experimental site was assessed. Reliable sensible heat flux was estimated with the use of accurate diurnal values of transfer coefficient of sensible heat. The performances of one α, two β and a modified α formulations in the estimation of latent heat flux were also assessed at the station. The Lee and Pielke ( β), modified Kondo ( α), Jacquemin and Noilhan ( α) and Noilhan and Planton ( β) parameterizations gave good estimation of latent heat flux. The coefficient of determination ( R 2) of the models between measured and estimated values were greater than 0.7. Low diurnal mean absolute error and root mean squared error values were found between measured and estimated fluxes. All the parameterizations gave reliable latent heat flux when diurnal values of transfer coefficients of moisture were used.

  15. Nanovalve-Controlled Cargo Release Activated by Plasmonic Heating

    PubMed Central

    Croissant, Jonas; Zink, Jeffrey I.

    2012-01-01

    The synthesis and operation of a light-operated nanovalve that controls the pore openings of mesoporous silica nanoparticles containing gold cores nanoparticles is described. The nanoparticles, consisting of 20 nm gold cores inside ~150 nm mesoporous silica spheres, were synthesized using a unique one-pot method. The nanovalves are comprised of cucurbit[6]uril rings encircling stalks that are attached to the ~2 nm pore openings. Plasmonic heating of the gold core raises the local temperature and decreases the ring-stalk binding constant, thereby unblocking the pore and releasing the cargo molecules that were preloaded inside. Bulk heating of the suspended particles to 60 °C is required to release the cargo, but no bulk temperature change was observed in the plasmonic heating release experiment. High intensity irradiation caused thermal damage to the silica particles, but low intensity illumination caused a sufficient local temperature increase to operate the valves without damaging the nanoparticles containers. These light-stimulated, thermally activated mechanized nanoparticles demonstrate a new system with potential utility for on-command drug release. PMID:22540671

  16. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 2; Evaluation of Estimates Using Independent Data

    NASA Technical Reports Server (NTRS)

    Yang, Song; Olson, William S.; Wang, Jian-Jian; Bell, Thomas L.; Smith, Eric A.; Kummerow, Christian D.

    2004-01-01

    Rainfall rate estimates from space-borne k&ents are generally accepted as reliable by a majority of the atmospheric science commu&y. One-of the Tropical Rainfall Measuring Mission (TRh4M) facility rain rate algorithms is based upon passive microwave observations fiom the TRMM Microwave Imager (TMI). Part I of this study describes improvements in the TMI algorithm that are required to introduce cloud latent heating and drying as additional algorithm products. Here, estimates of surface rain rate, convective proportion, and latent heating are evaluated using independent ground-based estimates and satellite products. Instantaneous, OP5resolution estimates of surface rain rate over ocean fiom the improved TMI algorithm are well correlated with independent radar estimates (r approx. 0.88 over the Tropics), but bias reduction is the most significant improvement over forerunning algorithms. The bias reduction is attributed to the greater breadth of cloud-resolving model simulations that support the improved algorithm, and the more consistent and specific convective/stratiform rain separation method utilized. The bias of monthly, 2.5 deg. -resolution estimates is similarly reduced, with comparable correlations to radar estimates. Although the amount of independent latent heating data are limited, TMI estimated latent heating profiles compare favorably with instantaneous estimates based upon dual-Doppler radar observations, and time series of surface rain rate and heating profiles are generally consistent with those derived from rawinsonde analyses. Still, some biases in profile shape are evident, and these may be resolved with: (a) additional contextual information brought to the estimation problem, and/or; (b) physically-consistent and representative databases supporting the algorithm. A model of the random error in instantaneous, 0.5 deg-resolution rain rate estimates appears to be consistent with the levels of error determined from TMI comparisons to collocated radar

  17. Validity of Five Satellite-Based Latent Heat Flux Algorithms for Semi-arid Ecosystems

    SciTech Connect

    Feng, Fei; Chen, Jiquan; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Liu, Meng; Zhang, Nannan; Guo, Yang; Yu, Jian; Sun, Minmin

    2015-12-09

    Accurate estimation of latent heat flux (LE) is critical in characterizing semiarid ecosystems. Many LE algorithms have been developed during the past few decades. However, the algorithms have not been directly compared, particularly over global semiarid ecosystems. In this paper, we evaluated the performance of five LE models over semiarid ecosystems such as grassland, shrub, and savanna using the Fluxnet dataset of 68 eddy covariance (EC) sites during the period 2000–2009. We also used a modern-era retrospective analysis for research and applications (MERRA) dataset, the Normalized Difference Vegetation Index (NDVI) and Fractional Photosynthetically Active Radiation (FPAR) from the moderate resolution imaging spectroradiometer (MODIS) products; the leaf area index (LAI) from the global land surface satellite (GLASS) products; and the digital elevation model (DEM) from shuttle radar topography mission (SRTM30) dataset to generate LE at region scale during the period 2003–2006. The models were the moderate resolution imaging spectroradiometer LE (MOD16) algorithm, revised remote sensing based Penman–Monteith LE algorithm (RRS), the Priestley–Taylor LE algorithm of the Jet Propulsion Laboratory (PT-JPL), the modified satellite-based Priestley–Taylor LE algorithm (MS-PT), and the semi-empirical Penman LE algorithm (UMD). Direct comparison with ground measured LE showed the PT-JPL and MS-PT algorithms had relative high performance over semiarid ecosystems with the coefficient of determination (R2) ranging from 0.6 to 0.8 and root mean squared error (RMSE) of approximately 20 W/m2. Empirical parameters in the structure algorithms of MOD16 and RRS, and calibrated coefficients of the UMD algorithm may be the cause of the reduced performance of these LE algorithms with R2 ranging from 0.5 to 0.7 and RMSE ranging from 20 to 35 W/m2 for MOD16, RRS and UMD. Sensitivity analysis showed that radiation and vegetation terms were the dominating

  18. Validity of Five Satellite-Based Latent Heat Flux Algorithms for Semi-arid Ecosystems

    DOE PAGES

    Feng, Fei; Chen, Jiquan; Li, Xianglan; ...

    2015-12-09

    Accurate estimation of latent heat flux (LE) is critical in characterizing semiarid ecosystems. Many LE algorithms have been developed during the past few decades. However, the algorithms have not been directly compared, particularly over global semiarid ecosystems. In this paper, we evaluated the performance of five LE models over semiarid ecosystems such as grassland, shrub, and savanna using the Fluxnet dataset of 68 eddy covariance (EC) sites during the period 2000–2009. We also used a modern-era retrospective analysis for research and applications (MERRA) dataset, the Normalized Difference Vegetation Index (NDVI) and Fractional Photosynthetically Active Radiation (FPAR) from the moderate resolutionmore » imaging spectroradiometer (MODIS) products; the leaf area index (LAI) from the global land surface satellite (GLASS) products; and the digital elevation model (DEM) from shuttle radar topography mission (SRTM30) dataset to generate LE at region scale during the period 2003–2006. The models were the moderate resolution imaging spectroradiometer LE (MOD16) algorithm, revised remote sensing based Penman–Monteith LE algorithm (RRS), the Priestley–Taylor LE algorithm of the Jet Propulsion Laboratory (PT-JPL), the modified satellite-based Priestley–Taylor LE algorithm (MS-PT), and the semi-empirical Penman LE algorithm (UMD). Direct comparison with ground measured LE showed the PT-JPL and MS-PT algorithms had relative high performance over semiarid ecosystems with the coefficient of determination (R2) ranging from 0.6 to 0.8 and root mean squared error (RMSE) of approximately 20 W/m2. Empirical parameters in the structure algorithms of MOD16 and RRS, and calibrated coefficients of the UMD algorithm may be the cause of the reduced performance of these LE algorithms with R2 ranging from 0.5 to 0.7 and RMSE ranging from 20 to 35 W/m2 for MOD16, RRS and UMD. Sensitivity analysis showed that radiation and vegetation terms were the dominating variables

  19. Screening for latent TB in patients with rheumatic disorders prior to biologic agents in a 'high-risk' TB population: comparison of two interferon gamma release assays.

    PubMed

    Melath, Sunil; Ismajli, Mediola; Smith, Robin; Patel, Ishita; Steuer, Alan

    2014-01-01

    Patients with rheumatic disorders treated with TNF inhibitors are at increased risk of developing TB. There is no 'gold-standard' for the diagnosis of latent TB prior to initiation of biologic agents. We report our own experience of comparing two interferon gamma release assays (IGRAs) in screening for latent TB in a 'high-risk' TB area in patients with rheumatic disorders. The study demonstrated good concordance between the two tests. We believe the additional cost of these assays is justified in high-risk populations prior to biologic agents, with 16% of the current study population with at least one positive IGRA assay.

  20. The use of simple physiological and environmental measures to estimate the latent heat transfer in crossbred Holstein cows.

    PubMed

    Santos, Severino Guilherme Caetano Gonçalves Dos; Saraiva, Edilson Paes; Pimenta Filho, Edgard Cavalcanti; Gonzaga Neto, Severino; Fonsêca, Vinicus França Carvalho; Pinheiro, Antônio da Costa; Almeida, Maria Elivania Vieira; de Amorim, Mikael Leal Cabral Menezes

    2017-02-01

    The aim of the present study was to estimate the heat transfer through cutaneous and respiratory evaporation of dairy cows raised in tropical ambient conditions using simple environmental and physiological measures. Twenty-six lactating crossbred cows (7/8 Holstein-Gir) were used, 8 predominantly white and 18 predominantly black. The environmental variables air temperature, relative humidity, black globe temperature, and wind speed were measured. Respiratory rate and coat surface temperature were measured at 0700, 0900, 1100, 1300, and 1500 h. The environmental and physiological data were used to estimate heat loss by respiratory (ER) and cutaneous evaporation (EC). Results showed that there was variation (P < 0.01) for respiratory rate depending on the times of the day. The highest values were recorded at 1100, 1300, and 1500 h, corresponding to 66.85 ± 10.20, 66.98 ± 7.80, and 65.65 ± 6.50 breaths/min, respectively. Thus, the amount of heat transferred via respiration ranged from 19.21 to 29.42 W/m(2). There was a variation from 31.6 to 38.8 °C for coat surface temperature; these values reflected a range of 55.52 to 566.83 W/m(2) for heat transfer via cutaneous evaporation. However, throughout the day, the dissipation of thermal energy through the coat surface accounted for 87.9 % total loss of latent heat, and the remainder (12.1 %) was via the respiratory tract. In conclusion, the predictive models based on respiratory rate and coat surface temperature may be used to estimate the latent heat loss in dairy cows kept confined in tropical ambient conditions.

  1. The use of simple physiological and environmental measures to estimate the latent heat transfer in crossbred Holstein cows

    NASA Astrophysics Data System (ADS)

    Santos, Severino Guilherme Caetano Gonçalves dos; Saraiva, Edilson Paes; Pimenta Filho, Edgard Cavalcanti; Gonzaga Neto, Severino; Fonsêca, Vinicus França Carvalho; Pinheiro, Antônio da Costa; Almeida, Maria Elivania Vieira; de Amorim, Mikael Leal Cabral Menezes

    2016-07-01

    The aim of the present study was to estimate the heat transfer through cutaneous and respiratory evaporation of dairy cows raised in tropical ambient conditions using simple environmental and physiological measures. Twenty-six lactating crossbred cows (7/8 Holstein-Gir) were used, 8 predominantly white and 18 predominantly black. The environmental variables air temperature, relative humidity, black globe temperature, and wind speed were measured. Respiratory rate and coat surface temperature were measured at 0700, 0900, 1100, 1300, and 1500 h. The environmental and physiological data were used to estimate heat loss by respiratory (ER) and cutaneous evaporation (EC). Results showed that there was variation (P < 0.01) for respiratory rate depending on the times of the day. The highest values were recorded at 1100, 1300, and 1500 h, corresponding to 66.85 ± 10.20, 66.98 ± 7.80, and 65.65 ± 6.50 breaths/min, respectively. Thus, the amount of heat transferred via respiration ranged from 19.21 to 29.42 W/m2. There was a variation from 31.6 to 38.8 °C for coat surface temperature; these values reflected a range of 55.52 to 566.83 W/m2 for heat transfer via cutaneous evaporation. However, throughout the day, the dissipation of thermal energy through the coat surface accounted for 87.9 % total loss of latent heat, and the remainder (12.1 %) was via the respiratory tract. In conclusion, the predictive models based on respiratory rate and coat surface temperature may be used to estimate the latent heat loss in dairy cows kept confined in tropical ambient conditions.

  2. The use of simple physiological and environmental measures to estimate the latent heat transfer in crossbred Holstein cows

    NASA Astrophysics Data System (ADS)

    Santos, Severino Guilherme Caetano Gonçalves dos; Saraiva, Edilson Paes; Pimenta Filho, Edgard Cavalcanti; Gonzaga Neto, Severino; Fonsêca, Vinicus França Carvalho; Pinheiro, Antônio da Costa; Almeida, Maria Elivania Vieira; de Amorim, Mikael Leal Cabral Menezes

    2017-02-01

    The aim of the present study was to estimate the heat transfer through cutaneous and respiratory evaporation of dairy cows raised in tropical ambient conditions using simple environmental and physiological measures. Twenty-six lactating crossbred cows (7/8 Holstein-Gir) were used, 8 predominantly white and 18 predominantly black. The environmental variables air temperature, relative humidity, black globe temperature, and wind speed were measured. Respiratory rate and coat surface temperature were measured at 0700, 0900, 1100, 1300, and 1500 h. The environmental and physiological data were used to estimate heat loss by respiratory (ER) and cutaneous evaporation (EC). Results showed that there was variation ( P < 0.01) for respiratory rate depending on the times of the day. The highest values were recorded at 1100, 1300, and 1500 h, corresponding to 66.85 ± 10.20, 66.98 ± 7.80, and 65.65 ± 6.50 breaths/min, respectively. Thus, the amount of heat transferred via respiration ranged from 19.21 to 29.42 W/m2. There was a variation from 31.6 to 38.8 °C for coat surface temperature; these values reflected a range of 55.52 to 566.83 W/m2 for heat transfer via cutaneous evaporation. However, throughout the day, the dissipation of thermal energy through the coat surface accounted for 87.9 % total loss of latent heat, and the remainder (12.1 %) was via the respiratory tract. In conclusion, the predictive models based on respiratory rate and coat surface temperature may be used to estimate the latent heat loss in dairy cows kept confined in tropical ambient conditions.

  3. The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosols on precipitation in organized deep convective systems

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-06-01

    A high-resolution, two-dimensional cloud-resolving model with spectral-bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low-level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity-governing equation shows that temperature buoyancy can enhance updrafts/downdrafts in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF-temperature buoyancy forcing. The balance among these terms determines the intensity of convection.

  4. Assimilating Latent Heat Fluxes From Meteorological Geostationary Satellite Data In A Hydrological Model At The Scale of 20000 Km2

    NASA Astrophysics Data System (ADS)

    Roulin, E.

    This paper focuses on the use of evapotranspiration estimated from Meteosat data and from conventional meteorological information in a simple hydrological model at the scale of the river Scheldt and the river Meuse basins in Belgium and France. The radia- tive balance at the ground is computed from infrared and visible counts, radiosound- ing profiles and meteorological information from the synoptic network (Roulin et al., 1996). Latent heat flux is computed using the Monin-Obukhov theory and data of an automatic station. The ratio between latent heat flux and energy balance at the automatic station is used to infer evapotranspiration over the whole area (Gellens- Meulenberghs, 2000). The hydrological model is adapted from a conceptual model onto a grid of cells with 50 km2 area. Seven vegetation covers are represented. Wa- ter from vegetation and two soil buckets is depleted regarding the Penman-Monteith potential evapotranspiration. A simple assimilation scheme of the evapotranspiration from Meteosat is applied for the year 1995. The results are compared with soil mois- ture data gathered during a field campaign in a study area of 2200 km2 by UCL (Auquière et al., 1997).

  5. Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment

    NASA Astrophysics Data System (ADS)

    de Melo Costa, Cíntia Carol; Maia, Alex Sandro Campos; Neto, José Domingues Fontenele; Oliveira, Steffan Edward Octávio; de Queiroz, João Paulo Araújo Fernandes

    2014-03-01

    The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands ( P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm2) and quantity per square centimeter (390 ± 9 cm-2). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m-2) and possessed the highest surface temperatures (39.47 ± 0.18 °C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

  6. Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment

    NASA Astrophysics Data System (ADS)

    de Melo Costa, Cíntia Carol; Maia, Alex Sandro Campos; Neto, José Domingues Fontenele; Oliveira, Steffan Edward Octávio; de Queiroz, João Paulo Araújo Fernandes

    2013-03-01

    The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands (P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm2) and quantity per square centimeter (390 ± 9 cm-2). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m-2) and possessed the highest surface temperatures (39.47 ± 0.18 °C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

  7. Use of four-dimensional data assimilation by Newtonian relaxation and latent-heat forcing to improve a mesoscale-model precipitation forecast - A case study

    NASA Technical Reports Server (NTRS)

    Wang, Wei; Warner, Thomas T.

    1988-01-01

    The Penn State/NCAR mesoscale model was used to study special static-initialization (SI) and dynamic-initialization (DI) techniques designed to improve short-range quantitative precipitation forecasts (QPFs), as applied to the heavy convective rainfall that occurred in Texas, Oklahoma, and Kansas during the May 9-10, 1979 SESAMY IV study period. In the DI procedure, two types of four-dimensional data assimilation (FDDA) procedures were used to incorporate data during a 12-h preforecast period, one using the Newtonian relaxation, the other using latent-heat forcing. It was found that combined use of either the preforecast or in-forecast latent-heat forcing with the Newtonian relaxation produced an improved forecast (relative to a conventional forecast procedure) of rainfall intensity compared to the use of the Newtonian relaxation alone. The use of the experimental SI with prescribed latent heating during the first forecast hour produced greatly improved rainfall rates.

  8. Interannual and Decadal Variability of Ocean Surface Latent Heat Flux as Seen from Passive Microwave Satellite Algorithms

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Jackson, Darren L.; Wick, Gary A.; Roberts, Brent; Miller, Tim L.

    2007-01-01

    Ocean surface turbulent fluxes are critical links in the climate system since they mediate energy exchange between the two fluid systems (ocean and atmosphere) whose combined heat transport determines the basic character of Earth's climate. Deriving physically-based latent and sensible heat fluxes from satellite is dependent on inferences of near surface moisture and temperature from coarser layer retrievals or satellite radiances. Uncertainties in these "retrievals" propagate through bulk aerodynamic algorithms, interacting as well with error properties of surface wind speed, also provided by satellite. By systematically evaluating an array of passive microwave satellite algorithms, the SEAFLUX project is providing improved understanding of these errors and finding pathways for reducing or eliminating them. In this study we focus on evaluating the interannual variability of several passive microwave-based estimates of latent heat flux starting from monthly mean gridded data. The algorithms considered range from those based essentially on SSM/I (e.g. HOAPS) to newer approaches that consider additional moisture information from SSM/T-2 or AMSU-B and lower tropospheric temperature data from AMSU-A. On interannual scales, variability arising from ENSO events and time-lagged responses of ocean turbulent and radiative fluxes in other ocean basins (as well as the extratropical Pacific) is widely recognized, but still not well quantified. Locally, these flux anomalies are of order 10-20 W/sq m and present a relevant "target" with which to verify algorithm performance in a climate context. On decadal time scales there is some evidence from reanalyses and remotely-sensed fluxes alike that tropical ocean-averaged latent heat fluxes have increased 5-10 W/sq m since the early 1990s. However, significant uncertainty surrounds this estimate. Our work addresses the origin of these uncertainties and provides statistics on time series of tropical ocean averages, regional space

  9. Gas motion through porous objects with nonuniform local distribution of heat-release sources

    NASA Astrophysics Data System (ADS)

    Levin, V. A.; Lutsenko, N. A.

    2008-09-01

    The gas motion through porous objects in the gravity force field with a non-uniform distribution of heat sources, which may arise as a result of natural or man-caused catastrophes (as the damaged power unit of the Chernobyl NPP), is investigated. The influence of different parameters of the heat-releasing zone on the process of cooling of such objects is analyzed with the aid of computational experiment. It is shown that the porous element heating is affected not only by the height of the heat-releasing zone and the heat-release intensity therein but also by the distance of the heat-releasing zone from the element inlet as well as by the width of the heat-releasing zone. The phenomenon of a reduction of the porous element heating with increasing distance of the heat-releasing zone from the porous element inlet is revealed. An ambiguous dependence of the porous object heating on the width of the heat-release zone is identified: at a growth of the heat-releasing zone width, the heating of the element may both increase and decrease depending on the distance of the heat-release zone from the element inlet.

  10. Usefulness of interferon-γ release assay for the diagnosis of latent tuberculosis infection in young children

    PubMed Central

    Kim, Young Kwang; Kim, Hae Ryun; Lee, Mi Kyung; Lim, In Seok

    2016-01-01

    Purpose Latent tuberculosis infection (LTBI) in young children may progress to severe active tuberculosis (TB) disease and serve as a reservoir for future transmission of TB disease. There are limited data on interferon-γ release assay (IGRA) performance in young children, which our research aims to address by investigating the usefulness of IGRA for the diagnosis of LTBI. Methods We performed a tuberculin skin test (TST) and IGRA on children who were younger than 18 years and were admitted to Chung-Ang University Hospital during May 2011–June 2015. Blood samples for IGRA were collected, processed, and interpreted according to manufacturer protocol. Results Among 149 children, 31 (20.8%) and 10 (6.7%) were diagnosed with LTBI and active pulmonary TB, respectively. In subjects lacking contact history with active TB patients, TST and IGRA results were positive in 41.4% (29 of 70) and 12.9% (9 of 70) subjects, respectively. The agreement (kappa) of TST and IGRA was 0.123. The control group, consisting of non-TB-infected subjects, showed no correlation between age and changes in interferon-γ concentration after nil antigen, TB-specific antigen, or mitogen stimulation in IGRAs (P=0.384, P=0.176, and P=0.077, respectively). In serial IGRAs, interferon-γ response to TB antigen increased in IGRA-positive LTBI subjects, but did not change considerably in initially IGRA-negative LTBI or control subjects. Conclusion The lack of decrease in interferon-γ response in young children indicates that IGRA could be considered for this age group. Serial IGRA tests might accurately diagnose LTBI in children lacking contact history with active TB patients. PMID:27462354

  11. Optical investigation of heat release and NOx production in combustion

    NASA Astrophysics Data System (ADS)

    Timmerman, B. H.; Patel, S.; Dunkley, P.; Bryanston-Cross, P. J.

    2005-08-01

    Two passive optical techniques are described to investigate combustion. Optical Emission Tomography (OET) is used for non-intrusive study of heat release through the detection of chemiluminescence by the hydroxyl radical that is generated in the burning process. The OET technique described here is based on a passive fibre-optic detection system, which allows spatially resolved high-frequency detection of the flame front in a combustion flame, where all fibres detect the emission signals simultaneously. The system withstands the high pressures and temperatures typically encountered in the harsh environments of gas turbine combustors and IC engines. The sensor-array is non-intrusive, low-cost, compact, simple to configure and can be quickly set up around a combustion field. The maximum acquisition rate is 2 kHz. This allows spatially resolved study of the fast phenomena in combustion. Furthermore, the production of NOx is investigated through the emission of green light as a result of adding tri-methyl-borate to a flame. In combustion, the tri-methyl-borate produces green luminescence in locations where NOx would be produced. Combining the green luminescence visualisation with OET detection of the hydroxyl radical allows monitoring of heat release and of NOx production areas, thus giving a means of studying both the burning process and the resulting NOx pollution.

  12. Regional CO2 and latent heat surface fluxes in the Southern Great Plains: Measurements, modeling, and scaling

    SciTech Connect

    Riley, W. J.; Biraud, S.C.; Torn, M.S.; Fischer, M.L.; Billesbach, D.P.; Berry, J.A.

    2009-08-15

    Characterizing net ecosystem exchanges (NEE) of CO{sub 2} and sensible and latent heat fluxes in heterogeneous landscapes is difficult, yet critical given expected changes in climate and land use. We report here a measurement and modeling study designed to improve our understanding of surface to atmosphere gas exchanges under very heterogeneous land cover in the mostly agricultural U.S. Southern Great Plains (SGP). We combined three years of site-level, eddy covariance measurements in several of the dominant land cover types with regional-scale climate data from the distributed Mesonet stations and Next Generation Weather Radar precipitation measurements to calibrate a land surface model of trace gas and energy exchanges (isotope-enabled land surface model (ISOLSM)). Yearly variations in vegetation cover distributions were estimated from Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index and compared to regional and subregional vegetation cover type estimates from the U.S. Department of Agriculture census. We first applied ISOLSM at a 250 m spatial scale to account for vegetation cover type and leaf area variations that occur on hundred meter scales. Because of computational constraints, we developed a subsampling scheme within 10 km 'macrocells' to perform these high-resolution simulations. We estimate that the Atmospheric Radiation Measurement Climate Research Facility SGP region net CO{sub 2} exchange with the local atmosphere was -240, -340, and -270 gC m{sup -2} yr{sup -1} (positive toward the atmosphere) in 2003, 2004, and 2005, respectively, with large seasonal variations. We also performed simulations using two scaling approaches at resolutions of 10, 30, 60, and 90 km. The scaling approach applied in current land surface models led to regional NEE biases of up to 50 and 20% in weekly and annual estimates, respectively. An important factor in causing these biases was the complex leaf area index (LAI) distribution within

  13. Regional CO2 and latent heat surface fluxes in the Southern Great Plains: Measurements, modeling, and scaling

    NASA Astrophysics Data System (ADS)

    Riley, W. J.; Biraud, S. C.; Torn, M. S.; Fischer, M. L.; Billesbach, D. P.; Berry, J. A.

    2009-12-01

    Characterizing net ecosystem exchanges (NEE) of CO2 and sensible and latent heat fluxes in heterogeneous landscapes is difficult, yet critical given expected changes in climate and land use. We report here a measurement and modeling study designed to improve our understanding of surface to atmosphere gas exchanges under very heterogeneous land cover in the mostly agricultural U.S. Southern Great Plains (SGP). We combined three years of site-level, eddy covariance measurements in several of the dominant land cover types with regional-scale climate data from the distributed Mesonet stations and Next Generation Weather Radar precipitation measurements to calibrate a land surface model of trace gas and energy exchanges (isotope-enabled land surface model (ISOLSM)). Yearly variations in vegetation cover distributions were estimated from Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index and compared to regional and subregional vegetation cover type estimates from the U.S. Department of Agriculture census. We first applied ISOLSM at a 250 m spatial scale to account for vegetation cover type and leaf area variations that occur on hundred meter scales. Because of computational constraints, we developed a subsampling scheme within 10 km "macrocells" to perform these high-resolution simulations. We estimate that the Atmospheric Radiation Measurement Climate Research Facility SGP region net CO2 exchange with the local atmosphere was -240, -340, and -270 gC m-2 yr-1 (positive toward the atmosphere) in 2003, 2004, and 2005, respectively, with large seasonal variations. We also performed simulations using two scaling approaches at resolutions of 10, 30, 60, and 90 km. The scaling approach applied in current land surface models led to regional NEE biases of up to 50 and 20% in weekly and annual estimates, respectively. An important factor in causing these biases was the complex leaf area index (LAI) distribution within cover types. Biases in

  14. Latent Heat Flux Estimate Through an Energy Water Balance Model and Land Surface Temperature from Remote Sensing

    NASA Astrophysics Data System (ADS)

    Corbari, Chiara; Sobrino, Jose A.; Mancini, Marco; Hidalgo, Victoria

    2011-01-01

    Soil moisture plays a key role in the terrestrial water cycle and is responsible for the partitioning of precipitation between runoff and infiltration. Moreover, surface soil moisture controls the redistribution of the incoming solar radiation on land surface into sensible and latent heat fluxes. Recent developments have been made to improve soil moisture dynamics predictions with hydrologic land surface models (LSMs) that compute water and energy balances between the land surface and the low atmosphere. However, most of the time soil moisture is confined to an internal numerical model variable mainly due to its intrinsic space and time variability and to the well known difficulties in assessing its value from remote sensing as from in situ measurements. In order to exploit the synergy between hydrological distributed models and thermal remote sensed data, FEST-EWB, a land surface model that solves the energy balance equation, was developed. In this hydrological model, the energy budget is solved looking for the representative thermodynamic equilibrium temperature (RET) defined as the land surface temperature that closes the energy balance equation. So using this approach, soil moisture is linked to the latent heat flux and then to LST. In this work the relationship between land surface temperature and soil moisture is analysed using LST from AHS (airborne hyperspectral scanner), with a spatial resolution of 2-4 m, LST from MODIS, with a spatial resolution of 1000 m, and thermal infrared radiometric ground measurements that are compared with the thermodynamic equilibrium temperature from the energy water balance model. Moreover soil moisture measurements were carried out during the airborne overpasses and then compared with SM from the hydrological model. An improvement of this well known inverse relationship between soil moisture and land surface temperature is obtained when the thermodynamic approach is used. The analysis of the scale effects of the different

  15. Spectral Retrieval of Latent Heating Profiles from TRMM PR data. Part 3; Moistening Estimates over Tropical Ocean Regions

    NASA Technical Reports Server (NTRS)

    Shige, S.; Takayabu, Y.; Tao, W.-K.

    2007-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of precipitation formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the tropics with the associated latent heating (LH) accounting for threefourths of the total heat energy available to the Earth's atmosphere. In the last decade, it has been established that standard products of LH from satellite measurements, particularly TRMM measurements, would be a valuable resource for scientific research and applications. Such products would enable new insights and investigations concerning the complexities of convection system life cycles, the diabatic heating controls and feedbacks related to rne-sosynoptic circulations and their forecasting, the relationship of tropical patterns of LH to the global circulation and climate, and strategies for improving cloud parameterizations In environmental prediction models. However, the LH and water vapor profile or budget (called the apparent moisture sink, or Q2) is closely related. This paper presented the development of an algorithm for retrieving Q2 using 'TRMM precipitation radar. Since there is no direct measurement of LH and Q2, the validation of algorithm usually applies a method called consistency check. Consistency checking involving Cloud Resolving Model (CRM)-generated LH and 42 profiles and algorithm-reconstructed is a useful step in evaluating the performance of a given algorithm. In this process, the CRM simulation of a time-dependent precipitation process (multiple-day time series) is used to obtain the required input parameters for a given algorithm. The algorithm is then used to "econsti-LKth"e heating and moisture profiles that the CRM simulation originally produced, and finally both sets of conformal estimates (model and algorithm) are compared each other. The results indicate that discrepancies between the reconstructed and CM-simulated profiles for Q2, especially at low levels

  16. Comparisons of sensible and latent heat fluxes using surface and aircraft data over adjacent wet and dry surfaces

    SciTech Connect

    Doran, J.C.; Hubbe, J.M.; Shaw, W.J.; Baldocchi, D.D.; Crawford, T.L.; Dobosy, R.J.; Meyers, T.J.

    1992-01-01

    In June 1991, a field study of surface fluxes of latent and sensible heat over heterogeneous surfaces was carried out near Boardman, Oregon (Doran et al., 1992). The object of the study was to develop improved methods of extrapolating from local measurements of fluxes to area-averaged values suitable for use in general circulation models (GCMs) applied to climate studies. A grid element in a GCM is likely to encompass regions whose fluxes vary significantly from one surface type to another. The problem of integrating these fluxes into a single, representative value for the whole element is not simple, and describing such a flux in terms of flux-gradient relationships, as is often done, presents additional difficulties.

  17. Interlayer-interaction dependence of latent heat in the Heisenberg model on a stacked triangular lattice with competing interactions.

    PubMed

    Tamura, Ryo; Tanaka, Shu

    2013-11-01

    We study the phase transition behavior of a frustrated Heisenberg model on a stacked triangular lattice by Monte Carlo simulations. The model has three types of interactions: the ferromagnetic nearest-neighbor interaction J(1) and antiferromagnetic third nearest-neighbor interaction J(3) in each triangular layer and the ferromagnetic interlayer interaction J([perpendicular]). Frustration comes from the intralayer interactions J(1) and J(3). We focus on the case that the order parameter space is SO(3)×C(3). We find that the model exhibits a first-order phase transition with breaking of the SO(3) and C(3) symmetries at finite temperature. We also discover that the transition temperature increases but the latent heat decreases as J([perpendicular])/J(1) increases, which is opposite to the behavior observed in typical unfrustrated three-dimensional systems.

  18. Applying a simple three-dimensional eddy correlation system for latent and sensible heat flux to contrasting forest canopies

    NASA Astrophysics Data System (ADS)

    Bernhofer, Ch.

    1992-06-01

    A simple eddy correlation system is presented that allows on-line calculation of latent and sensible heat fluxes. The system is composed of a three dimensional propeller anemometer, a thermocouple and a capacitance relative humidity sensor. Results from two contrasting sites demonstrate the capability of the system to measure turbulent fluxes under varying conditions. A dry mixed (dominantly coniferous) forest in hilly terrain in Austria is compared to a well irrigated, heavily transpiring, deciduous pecan orchard in the Southwest of the US. The US site shows insufficient closure of the energy balance that is attributed to non-turbulent fluxes under advective conditions in a stable boundary layer (Blanford et al., 1991) while the Austrian site exhibits almost perfect closure with the use of the very same instruments when the boundary layer is convective and advection is negligible.

  19. Development of media for dynamic latent heat storage for the low-temperature range. Part 1: Thermal analyses of selected salt hydrate systems

    NASA Technical Reports Server (NTRS)

    Kanwischer, H.; Tamme, R.

    1985-01-01

    Phase change temperatures and phase change enthalpies of seventeen salt hydrates, three double salts, and four eutectics were measured thermodynamically and the results reported herein. Good results were obtained, especially for congruently melting salt hydrates. Incongruently melting salt hydrates appear less suitable for heat storage applications. The influence of the second phase - water, acid and hydroxide - to the latent heat is described. From these results, basic values of the working temperatures and storage capabilities of various storage media compositions may be derived.

  20. Radio Heating of Lunar Soil to Release Gases

    NASA Technical Reports Server (NTRS)

    Chui, Talso; Penanen, Konstantin

    2006-01-01

    A report proposes the development of a system to collect volatile elements and compounds from Lunar soil for use in supporting habitation and processing into rocket fuel. Prior exploratory missions revealed that H2, He, and N2 are present in Lunar soil and there are some indications that water ice may also be present. The proposed system would include a shroud that would be placed on the Lunar surface. Inside the shroud would be a radio antenna aimed downward. The antenna would be excited at a suitably high power and at a frequency chosen to optimize the depth of penetration of radio waves into the soil. The radio waves would heat the soil, thereby releasing volatiles bound to soil particles. The escaping volatiles would be retained by the shroud and collected by condensation in a radiatively cooled vessel connected to the shroud. It has been estimated that through radio-frequency heating at a power of 10 kW for one day, it should be possible to increase the temperature of a soil volume of about 1 cubic m by about 200 C -- an amount that should suffice for harvesting a significant quantity of volatile material.

  1. The role of chemical additives to the phase change process of CaCl2.6H2O to optimize its performance as latent heat energy storage system

    NASA Astrophysics Data System (ADS)

    Sutjahja, I. M.; U, S. Rahayu A.; Kurniati, Nia; Pallitine, Ivyalentine D.; Kurnia, D.

    2016-08-01

    CaCl2.6H2O is one of salt hydrate based phase change material (PCM) which is suitable for room air-temperature stabilizer because it has the melting temperature just above the human comfort zone temperature (Tm ∼⃒ 29 oC) and a relatively large heat entalphy (AH ∼⃒ 190 kJ/kg). This paper reports the role of the type of chemical additives to PCM CaCl2.6H2O to the phase change process throughout the solidification process or heat release in order to optimize its performance as latent heat energy storage system. In this research we used several kinds of chemical additive, namely SrCl2.6H2O (1.0 wt%), BaCO3 (0.5 wt%), and K2CO3 (0.5 wt%). In terms of its latent time for phase change process the order the effectiveness of those chemical additives are reduced from SrCl2.6H2O, BaCO3and K2CO3. We found that this is also related to their role in suppression supercooling and phase separation effects which occurs during crystallization process of CaCl2.6H2O.

  2. Evidence for increased latent heat transport during the Cretaceous (Albian) greenhouse warming

    USGS Publications Warehouse

    Ufnar, David F.; Gonzalez, Luis A.; Ludvigson, Greg A.; Brenner, Richard L.; Witzke, B.J.

    2004-01-01

    Quantitative estimates of increased heat transfer by atmospheric H 2O vapor during the Albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport. Sphaerosiderite ??18O values in paleosols of the North American Cretaceous Western Interior Basin are a proxy for meteoric ??18O values, and mass-balance modeling results suggest that Albian precipitation rates exceeded modern rates at both mid and high latitudes. Comparison of modeled Albian and modern precipitation minus evaporation values suggests amplification of the Albian moisture deficit in the tropics and moisture surplus in the mid to high latitudes. The tropical moisture deficit represents an average heat loss of ???75 W/m2 at 10??N paleolatitude (at present, 21 W/m2). The increased precipitation at higher latitudes implies an average heat gain of ???83 W/m2 at 45??N (at present, 23 W/m2) and of 19 W/m2 at 75??N (at present, 4 W/m2). These estimates of increased poleward heat transfer by H2O vapor during the Albian may help to explain the reduced equator-to-pole temperature gradients. ?? 2004 Geological Society of America.

  3. Performance analysis of a latent heat storage system with phase change material for new designed solar collectors in greenhouse heating

    SciTech Connect

    Benli, Hueseyin; Durmus, Aydin

    2009-12-15

    The continuous increase in the level of greenhouse gas emissions and the rise in fuel prices are the main driving forces behind the efforts for more effectively utilize various sources of renewable energy. In many parts of the world, direct solar radiation is considered to be one of the most prospective sources of energy. In this study, the thermal performance of a phase change thermal storage unit is analyzed and discussed. The storage unit is a component of ten pieced solar air collectors heating system being developed for space heating of a greenhouse and charging of PCM. CaCl{sub 2}6H{sub 2}O was used as PCM in thermal energy storage with a melting temperature of 29 C. Hot air delivered by ten pieced solar air collector is passed through the PCM to charge the storage unit. The stored heat is utilized to heat ambient air before being admitted to a greenhouse. This study is based on experimental results of the PCM employed to analyze the transient thermal behavior of the storage unit during the charge and discharge periods. The proposed size of collectors integrated PCM provided about 18-23% of total daily thermal energy requirements of the greenhouse for 3-4 h, in comparison with the conventional heating device. (author)

  4. Development of a Model for the Heat Release Rate of Wood. A Status Report.

    DTIC Science & Technology

    1985-05-01

    designates the slice bounded by the rear surface 0 ambient or original *0 oxygen R radiation rel release S front surface of specimen Vol volatiles ix w water...rate is one of the most important fire properties of a material. Whether a room fire will attain flashover depends on the total heat release rate of all...function of the net heat transfer through their front surface . A number of calorimeters have been developed to measure the heat release , rate per unit

  5. Solar passive ceiling system. Final report. [Passive solar heating system with venetian blind reflectors and latent heat storage in ceiling

    SciTech Connect

    Schneider, A.R.

    1980-01-01

    The construction of a 1200 square foot building, with full basement, built to be used as a branch library in a rural area is described. The primary heating source is a passive solar system consisting of a south facing window system. The system consists of: a set of windows located in the south facing wall only, composed of double glazed units; a set of reflectors mounted in each window which reflects sunlight up to the ceiling (the reflectors are similar to venetian blinds); a storage area in the ceiling which absorbs the heat from the reflected sunlight and stores it in foil salt pouches laid in the ceiling; and an automated curtain which automatically covers and uncovers the south facing window system. The system is totally passive and uses no blowers, pumps or other active types of heat distribution equipment. The building contains a basement which is normally not heated, and the north facing wall is bermed four feet high around the north side.

  6. Selective peptide inhibitors of antiapoptotic cellular and viral Bcl-2 proteins lead to cytochrome c release during latent Kaposi's sarcoma-associated herpesvirus infection.

    PubMed

    Burrer, Christine M; Foight, Glenna W; Keating, Amy E; Chan, Gary C

    2016-01-04

    Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with B-cell lymphomas including primary effusion lymphoma and multicentric Castleman's disease. KSHV establishes latency within B cells by modulating or mimicking the antiapoptotic Bcl-2 family of proteins to promote cell survival. Our previous BH3 profiling analysis, a functional assay that assesses the contribution of Bcl-2 proteins towards cellular survival, identified two Bcl-2 proteins, cellular Mcl-1 and viral KsBcl-2, as potential regulators of mitochondria polarization within a latently infected B-cell line, Bcbl-1. In this study, we used two novel peptide inhibitors identified in a peptide library screen that selectively bind KsBcl-2 (KL6-7_Y4eK) or KsBcl-2 and Mcl-1 (MS1) in order to decipher the relative contribution of Mcl-1 and KsBcl-2 in maintaining mitochondrial membrane potential. We found treatment with KL6-7_Y4eK and MS1 stimulated a similar amount of cytochrome c release from mitochondria isolated from Bcbl-1 cells, indicating that inhibition of KsBcl-2 alone is sufficient for mitochondrial outer membrane permiabilzation (MOMP) and thus apoptosis during a latent B cell infection. In turn, this study also identified and provides a proof-of-concept for the further development of novel KsBcl-2 inhibitors for the treatment of KSHV-associated B-cell lymphomas via the targeting of latently infected B cells.

  7. Effect of latent heat in boiling water on the synthesis of gold nanoparticles of different sizes by using the Turkevich method.

    PubMed

    Ding, Wenchao; Zhang, Peina; Li, Yijing; Xia, Haibing; Wang, Dayang; Tao, Xutang

    2015-02-02

    The Turkevich method, involving the reduction of HAuCl4 with citrate in boiling water, allows the facile production of monodisperse, quasispherical gold nanoparticles (AuNPs). Although, it is well-known that the size of the AuNPs obtained with the same recipe vary slightly (as little as approximately 4 nm), but noticeably, from one report to another, it has rarely been studied. The present work demonstrates that this size variation can be reconciled by the small, but noticeable, effect that the latent heat in boiling water has on the size of the AuNPs obtained by using the Turkevich method. The increase in latent heat during water boiling caused an approximately 3 nm reduction in the size of the as-prepared AuNPs; this reduction in size is mainly a result of accelerated nucleation driven by the extra heat. It was further demonstrated that, the heating temperature can be utilized as an additional measure to adjust the growth rate of AuNPs during the reduction of HAuCl4 with citrate in boiling water. Therefore, the latent heat of boiling solvents may provide one way to control nucleation and growth in the synthesis of monodisperse nanoparticles.

  8. Experimental Investigation of Latent Heat Thermal Energy Storage for Bi-Modal Solar Thermal Propulsion

    DTIC Science & Technology

    2014-06-01

    However, when cut open and examined, it was seen that small cracks had still formed in the internal boron nitride liners . An additional 80% fill...factor test was completed with a test section constructed entirely with SIC-6 grade graphite (i.e. no BN liner ) as a follow-on to materials...sectioning an 80% fill factor solar furnace test article. The graphite absorber / heat spreader, boron nitride liner , and silicon are shown. Test section

  9. Thermal energy storage - overview and specific insight into nitrate salts for sensible and latent heat storage.

    PubMed

    Pfleger, Nicole; Bauer, Thomas; Martin, Claudia; Eck, Markus; Wörner, Antje

    2015-01-01

    Thermal energy storage (TES) is capable to reduce the demand of conventional energy sources for two reasons: First, they prevent the mismatch between the energy supply and the power demand when generating electricity from renewable energy sources. Second, utilization of waste heat in industrial processes by thermal energy storage reduces the final energy consumption. This review focuses mainly on material aspects of alkali nitrate salts. They include thermal properties, thermal decomposition processes as well as a new method to develop optimized salt systems.

  10. Thermal Assessment of a Latent-Heat Energy Storage Module During Melting and Freezing for Solar Energy Applications

    NASA Astrophysics Data System (ADS)

    Ramos Archibold, Antonio

    Capital investment reduction, exergetic efficiency improvement and material compatibility issues have been identified as the primary techno-economic challenges associated, with the near-term development and deployment of thermal energy storage (TES) in commercial-scale concentrating solar power plants. Three TES techniques have gained attention in the solar energy research community as possible candidates to reduce the cost of solar-generated electricity, namely (1) sensible heat storage, (2) latent heat (tank filled with phase change materials (PCMs) or encapsulated PCMs packed in a vessel) and (3) thermochemical storage. Among these the PCM macro-encapsulation approach seems to be one of the most-promising methods because of its potential to develop more effective energy exchange, reduce the cost associated with the tank and increase the exergetic efficiency. However, the technological barriers to this approach arise from the encapsulation techniques used to create a durable capsule, as well as an assessment of the fundamental thermal energy transport mechanisms during the phase change. A comprehensive study of the energy exchange interactions and induced fluid flow during melting and solidification of a confined storage medium is reported in this investigation from a theoretical perspective. Emphasis has been placed on the thermal characterization of a single constituent storage module rather than an entire storage system, in order to, precisely capture the energy exchange contributions of all the fundamental heat transfer mechanisms during the phase change processes. Two-dimensional, axisymmetric, transient equations for mass, momentum and energy conservation have been solved numerically by the finite volume scheme. Initially, the interaction between conduction and natural convection energy transport modes, in the absence of thermal radiation, is investigated for solar power applications at temperatures (300--400°C). Later, participating thermal radiation

  11. Towards the development of latent heat storage electrodes for electroporation-based therapies

    NASA Astrophysics Data System (ADS)

    Arena, Christopher B.; Mahajan, Roop L.; Rylander, Marissa Nichole; Davalos, Rafael V.

    2012-08-01

    Phase change materials (PCMs) capable of storing a large amount of heat upon transitioning from the solid-to-liquid state have been widely used in the electronics and construction industries for mitigating temperature development. Here, we show that they are also beneficial for reducing the peak tissue temperature during electroporation-based therapies. A numerical model is developed of irreversible electroporation (IRE) performed with hollow needle electrodes filled with a PCM. Results indicate that this electrode design can be utilized to achieve large ablation volumes while reducing the probability for thermal damage.

  12. A field study of the effects of inhomogeneities of surface sensible and latent heat fluxes

    SciTech Connect

    Doran, J.C.; Barnes, F.J.; Coulter, R.L.; Crawford, T.L.

    1992-01-01

    In recent years, the problem of characterizing turbulent fluxes of heat, momentum, and moisture over inhomogeneous surfaces has received increasing attention. This issue is relevant to the performance of general circulation models (GCMs), in which a single grid element can encompass a variety of surface and topographical features. Although considerable progress has been made in describing the energy balance at a surface partially covered by vegetation, less is known about how to treat adjacent regions of sharply contrasting surface characteristics. One difficulty is the scarcity of suitable data sets with which to study the problem, particularly on scales of tens to hundreds of kilometers.

  13. Effects of anthropogenic heat release upon the urban climate in a Japanese megacity.

    PubMed

    Narumi, Daisuke; Kondo, Akira; Shimoda, Yoshiyuki

    2009-05-01

    This report presents results of investigations of the influence of anthropogenic heat release in Japanese megacity (Keihanshin district) upon the urban climate, using the energy database [Shimoda et al., 1999. Estimation and evaluation of artificial waste heat in urban area. Selected Papers from the Conference ICB-ICUC'99 WCASP-50 WMO/TD no. 1026] as a part of the land-surface boundary conditions of a mesoscale meteorological simulation model. The calculated results related to atmospheric temperature distribution were similar to observed values not only for daily averages but also for amplitudes and phases of diurnal change. To reproduce accurately, it is essential to reproduce urban characteristics such as an urban canopy and anthropogenic heat release in a fine resolution mesh. We attempted an analysis using current data for anthropogenic heat and under uniform heat release conditions, to investigate temporal and spatial characteristics in relation to the influence of anthropogenic heat release on the urban climate. The results of investigation into the influence of anthropogenic heat release on atmospheric temperature using current data indicate that the amount of heat released is lower at night than during the day, but the temperature rise is nearly 3 times greater. Results of investigation into the influence of anthropogenic heat release on wind systems using current data indicate that the onset of land breezes is delayed, particularly in a coastal area. Investigation into the temporal characteristics related to the influence of anthropogenic heat release under uniform heat release conditions showed a maximum influence on temperature during the predawn period.

  14. Experimental Investigation on the Effects of Chemical Heat Release in the Reacting Turbulent Plane Shear Layer.

    DTIC Science & Technology

    1981-01-01

    RD-Ai44 482 EXPERIMENTAL INVESTIGATION ON THE EFFECTS OF CHEMICAL 1/2 HEAT RELEASE IN THE..(U) CALIFORNIA INST OF TECH PASADENA A K WIALLACE JAN 81...TITLE (end Subtitle) S. TYPE OF REPORT 46 PERIOD COVERED Experimental Investigation on the Effects of Chemical Heat Release in the Reacting"Turbulent...Institute of Technology. 19. KEY 140ROS (Continue on reverse stdo of necesaray end identity by block number) Turbulence, combustion, shear layer, heat

  15. Estimation of Mesoscale Atmospheric Latent Heating Profiles from TRMM Rain Statistics Utilizing a Simple One-Dimensional Model

    NASA Technical Reports Server (NTRS)

    Iacovazzi, Robert A., Jr.; Prabhakara, C.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    In this study, a model is developed to estimate mesoscale-resolution atmospheric latent heating (ALH) profiles. It utilizes rain statistics deduced from Tropical Rainfall Measuring Mission (TRMM) data, and cloud vertical velocity profiles and regional surface thermodynamic climatologies derived from other available data sources. From several rain events observed over tropical ocean and land, ALH profiles retrieved by this model in convective rain regions reveal strong warming throughout most of the troposphere, while in stratiform rain regions they usually show slight cooling below the freezing level and significant warming above. The mesoscale-average, or total, ALH profiles reveal a dominant stratiform character, because stratiform rain areas are usually much larger than convective rain areas. Sensitivity tests of the model show that total ALH at a given tropospheric level varies by less than +/- 10 % when convective and stratiform rain rates and mesoscale fractional rain areas are perturbed individually by 1 15 %. This is also found when the non-uniform convective vertical velocity profiles are replaced by one that is uniform. Larger variability of the total ALH profiles arises when climatological ocean- and land-surface temperatures (water vapor mixing ratios) are independently perturbed by +/- 1.0 K (+/- 5 %) and +/- 5.0 K (+/- 15 %), respectively. At a given tropospheric level, such perturbations can cause a +/- 25 % variation of total ALH over ocean, and a factor-of-two sensitivity over land. This sensitivity is reduced substantially if perturbations of surface thermodynamic variables do not change surface relative humidity, or are not extended throughout the entire model evaporation layer. The ALH profiles retrieved in this study agree qualitatively with tropical total diabatic heating profiles deduced in earlier studies. Also, from January and July 1999 ALH-profile climatologies generated separately with TRMM Microwave Imager and Precipitation Radar rain

  16. Latent heat loss of dairy cows in an equatorial semi-arid environment.

    PubMed

    da Silva, Roberto Gomes; Maia, Alex Sandro Campos; de Macedo Costa, Leonardo Lelis; de Queiroz, João Paulo A Fernandes

    2012-09-01

    The present study aimed to evaluate evaporative heat transfer of dairy cows bred in a hot semi-arid environment. Cutaneous (E(S)) and respiratory (E(R)) evaporation were measured (810 observations) in 177 purebred and crossbred Holstein cows from five herds located in the equatorial semi-arid region, and one herd in the subtropical region of Brazil. Rectal temperature (T(R)), hair coat surface temperature (T(S)) and respiratory rate (F(R)) were also measured. Observations were made in the subtropical region from August to December, and in the semi-arid region from April to July. Measurements were done from 1100 to 1600 hours, after cows remained in a pen exposed to the sun. Environmental variables measured in the same locations as the animals were black globe temperature (T(G)), air temperature (T(A)), wind speed (U), and partial air vapour pressure (P(V)). Data were analysed by mixed models, using the least squares method. Results showed that average E(S) and E(R) were higher in the semi-arid region (117.2 W m(-2) and 44.0 W m(-2), respectively) than in the subtropical region (85.2 W m(-2) and 30.2 W m(-2), respectively). Herds and individual cows were significant effects (P < 0.01) for all traits in the semi-arid region. Body parts did not affect T(S) and E(S) in the subtropical region, but was a significant effect (P < 0.01) in the semi-arid region. The average flank T(S) (42.8°C) was higher than that of the neck and hindquarters (39.8°C and 41.6°C, respectively). Average E(S) was higher in the neck (133.3 W m(-2)) than in the flank (116.2 W m(-2)) and hindquarters (98.6 W m(-2)). Coat colour affected significantly both T(S) and E(S) (P < 0.01). Black coats had higher T(S) and E(S) in the semi-arid region (41.7°C and 117.2 W m(-2), respectively) than white coats (37.2°C and 106.7 W m(-2), respectively). Rectal temperatures were almost the same in both subtropical and semi-arid regions. The results highlight the need for improved management methods specific

  17. Validation of HOAPS and ERA Interim latent heat fluxes against parameterizations applied to RV Polarstern data for 1995-1997

    NASA Astrophysics Data System (ADS)

    Bumke, Karl; Kinzel, Julian

    2014-05-01

    Latent heat fluxes (LHF) represent a crucial component of the global energy cycle. As LHF provide one of the upper boundary conditions for the oceanic component of coupled atmosphere-ocean circulation models, it is desirable to rely on one consistent LHF data source with sufficient spatial and temporal resolution. Remotely sensed LHF, particularly the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS) climatology, are considered to fulfil this criterion. However, the validity of HOAPS LHF needs to be investigated to assess its potential of reliably representing an essential part of the global freshwater cycle. Within this study, a validation of HOAPS-3.0-based LHF at pixel-level resolution for 1995-1997 is performed over the Atlantic basin. A recently developed bulk flux algorithm termed OCEANET (Bumke et al., 2013), derived from turbulence measurements onboard R/V Polarstern by inertial dissipation method, is applied to hourly bulk measurements obtained during 19 Atlantic cruises of R/V Polarstern. Its LHF output serves as the in-situ validation data source, which is supplemented by ERA-Interim reanalysis data. By means of the nearest-neighbor approach, a collocation of HOAPS- to OCEANET- and ERA-Interim data is carried out. Bias analyses suggest that HOAPS LHF are on average significantly underestimated compared to OCEANET and ERA-Interim (-8 W/m²). A sub-division into latitudinal bands resolves absolute biases exceeding -20 W/m² in the tropics. As the minor differences between the HOAPS- and OCEANET-based transfer coefficients lie within the uncertainty range inherent to bulk flux parameterizations, it is suggested that the significant LHF deviations for the most part arise from deviations among the bulk input variables. Investigations of bulk input parameters reveal that the observed negative LHF biases within the HOAPS record are mainly associated with an overrepresentation of air specific humidity for 20°S - 60°N. Latitudinal

  18. Comparison between global latent heat flux computed from multisensor (SSM/I and AVHRR) and from in situ data

    NASA Technical Reports Server (NTRS)

    Jourdan, Didier; Gautier, Catherine

    1995-01-01

    Comprehensive Ocean-Atmosphere Data Set (COADS) and satellite-derived parameters are input to a similarity theory-based model and treated in completely equivalent ways to compute global latent heat flux (LHF). In order to compute LHF exclusively from satellite measurements, an empirical relationship (Q-W relationship) is used to compute the air mixing ratio from Special Sensor Microwave/Imager (SSM/I) precipitable water W and a new one is derived to compute the air temperature also from retrieved W(T-W relationship). First analyses indicate that in situ and satellite LHF computations compare within 40%, but systematic errors increase the differences up to 100% in some regions. By investigating more closely the origin of the discrepancies, the spatial sampling of ship reports has been found to be an important source of error in the observed differences. When the number of in situ data records increases (more than 20 per month), the agreement is about 50 W/sq m rms (40 W/sq m rms for multiyear averages). Limitations of both empirical relationships and W retrieval errors strongly affect the LHF computation. Systematic LHF overestimation occurs in strong subsidence regions and LHF underestimation occurs within surface convergence zones and over oceanic upwelling areas. The analysis of time series of the different parameters in these regions confirms that systematic LHF discrepancies are negatively correlated with the differences between COADS and satellite-derived values of the air mixing ratio and air temperature. To reduce the systematic differences in satellite-derived LHF, a preliminary ship-satellite blending procedure has been developed for the air mixing ratio and air temperature.

  19. Evaluation of three satellite-based latent heat flux algorithms over forest ecosystems using eddy covariance data.

    PubMed

    Yao, Yunjun; Zhang, Yuhu; Zhao, Shaohua; Li, Xianglan; Jia, Kun

    2015-06-01

    We have evaluated the performance of three satellite-based latent heat flux (LE) algorithms over forest ecosystems using observed data from 40 flux towers distributed across the world on all continents. These are the revised remote sensing-based Penman-Monteith LE (RRS-PM) algorithm, the modified satellite-based Priestley-Taylor LE (MS-PT) algorithm, and the semi-empirical Penman LE (UMD-SEMI) algorithm. Sensitivity analysis illustrates that both energy and vegetation terms has the highest sensitivity compared with other input variables. The validation results show that three algorithms demonstrate substantial differences in algorithm performance for estimating daily LE variations among five forest ecosystem biomes. Based on the average Nash-Sutcliffe efficiency and root-mean-squared error (RMSE), the MS-PT algorithm has high performance over both deciduous broadleaf forest (DBF) (0.81, 25.4 W/m(2)) and mixed forest (MF) (0.62, 25.3 W/m(2)) sites, the RRS-PM algorithm has high performance over evergreen broadleaf forest (EBF) (0.4, 28.1 W/m(2)) sites, and the UMD-SEMI algorithm has high performance over both deciduous needleleaf forest (DNF) (0.78, 17.1 W/m(2)) and evergreen needleleaf forest (ENF) (0.51, 28.1 W/m(2)) sites. Perhaps the lower uncertainties in the required forcing data for the MS-PT algorithm, the complicated algorithm structure for the RRS-PM algorithm, and the calibrated coefficients of the UMD-SEMI algorithm based on ground-measured data may explain these differences.

  20. Evaluation of heat shock proteins for discriminating between latent tuberculosis infection and active tuberculosis: A preliminary report.

    PubMed

    Shekhawat, Seema D; Purohit, Hemant J; Taori, Girdhar M; Daginawala, Hatim F; Kashyap, Rajpal S

    2016-01-01

    The diagnosis of a latent tuberculosis infection (LTBI) is of the utmost concern. The available tests, the tuberculin skin test (TST) and the Quantiferon-TB Gold test (QFT-G) cannot discriminate between active TB and LTBI. Therefore, the aim of the study is to identify new biomarkers that can discriminate between active TB and LTBI and can also assess the risk of the individual developing active TB. In total, 55 blood samples were collected, of which 10 samples were from the active TB infection group, 10 were from the high-risk exposure group, 23 were from the low-risk exposure group, and 12 were from healthy controls living in a non-TB endemic area. A panel of heat shock proteins (Hsps), including host Hsp25, Hsp60, Hsp70, and Hsp90 and Mycobacterium tuberculosis (MTB) Hsp16, were evaluated in all of the collected samples using ELISA. The levels of the host Hsp(s) (Hsp25, Hsp60, Hsp70 and Hsp90) and MTB Hsp16 were significantly (p<0.05) elevated in the active TB group compared to the high-risk exposure group, the low-risk exposure group and the control group. Notably, the levels of the same panel of Hsp(s) were elevated in the high-risk exposure group compared to the low-risk exposure group. On follow-up, out of the 10 high-risk exposure participants, 3 converted into active TB, indicating that this group has the highest risk of developing TB. Thus, the evaluated panel of Hsp(s) can discriminate between LTBI and active TB. They can also identify individuals who are at the highest risk of developing active TB. Because they can be rapidly detected, Hsp(s) have an edge over the existing diagnostic tools for LTBI. The evaluation of these proteins will be useful in designing better diagnostic methods for LTBI.

  1. Prevalence of latent tuberculosis infection in Sudan: a case–control study comparing interferon-γ release assay and tuberculin skin test

    PubMed Central

    2013-01-01

    Background Most people exposed to M. tuberculosis show no evidence of clinical disease. Five to 10% of individuals with latent infection progress to develop overt disease during their life time. Identification of people with latent TB infection will increase case detection rates and may dictate new treatment policies to control tuberculosis. This study aimed to determine LTBI point prevalence in a population from Sudan using two different diagnostic methods: the tuberculin skin test (TST) and the IFN-γ release assay (IGRA). Methods This was a prospective, community-based and case-controlled study. Following informed consent, household contacts (HHCs; n = 98) of smear-positive index cases and Community controls (CCs; 186), were enrolled. Tuberculin skin test (TST), whole blood stimulation with ESAT-6/CFP-10 ± TB7.7 antigens or purified protein derivative (PPD) and IFN-γ levels determination with ELISA were performed. The levels of IFN-γ and TST induration between the CCs and the HHCs were compared using student t-test, Chi-square and Kappa coefficient. Pearson correlation test was used to compare TST and IFN-γ. P levels of <0.05 were considered significant. Results TST induration of ≥ 10 mm gave an LTBI point prevalence of 327 cases/1000 individuals among HHCs compared to 126 cases/1000 individuals among CCs (p = 0.000). PPD-induced IFN-γ release assay gave an LTBI point prevalence of 418 cases/1000 individuals among HHCs compared to 301 cases/1000 individuals among CCs (p =0.06). On the other hand ESAT-6/CFP-10 ± TB7.7-induced IFN-γ gave an LTBI point prevalence of 429 cases/1000 individuals among HHCs compared to 268 cases/1000 individuals among CCs (p = 0.01). IFN-γ productions levels induced by ESAT-6/CPF-10 ± TB7.7 antigens in HHCS and CCs were not significantly different from those induced by PPD (p = 0.7). Conclusion IFN-γ release assay (IGRA) gave higher LTBI point prevalence compared to TST in HHCs and CCs. PPD

  2. Effect of heat release on movement characteristics of shock train in an isolator

    NASA Astrophysics Data System (ADS)

    Zhang, Chenlin; Chang, Juntao; Liu, MengMeng; Feng, Shuo; Shi, Wen; Bao, Wen

    2017-04-01

    In this paper, the effect of heat release on movement characteristics of shock train is numerically investigated in an isolator. It is found that the combustion heat release has a distinct effect on the shock train movement characteristics in the isolator. With increasing heat release, a shock train gradually forms and then propagates toward isolator entrance. In process of shock train formation, separation bubbles before injection ports entrain the high temperature burning gas into the boundary layer, which causes the shock train to shrink and stretch, and changes in configuration and number of shock waves. At the same time, the system force fluctuates. In addition, the shock train movement is divided into three stages, which have different wall pressure distribution. It is believed that these findings have a help the better understanding of the effect of heat release on the movement characteristics of shock train in an isolator.

  3. The Contribution of Englacial Latent Heat Transfer to Seaward Ice Flux from Regions of Convergent and Divergent Ice Flow in Western Greenland

    NASA Astrophysics Data System (ADS)

    Poinar, K.; Joughin, I. R.

    2014-12-01

    Glacial meltwater can refreeze within firn and crevasses, warming the ice through latent heat transfer. The consequent softening of the ice has been identified as a potential destabilization mechanism for the Greenland Ice Sheet, which would flow more quickly seaward with lower viscosity. We calculate the effect of meltwater refreezing within firn and englacial features on ice temperature and viscosity in two contrasting areas of western Greenland: Jakobshavn Isbrae, a convergent, fast-flowing outlet glacier, and the Pakitsoq area (Swiss Camp) directly to its north, a "dead zone" experiencing slow, divergent flow because of its location between two outlet glaciers. We explore how much refreezing affects the seaward velocity of ice in each location by comparing our modeled temperature profiles to borehole data. Pakitsoq ice shows significant englacial latent heat transfer, or cryo-hydrologic warming, while the ice in Jakobshavn has warmed largely due to percolation within the firn. We find that the Pakitsoq region is rather unique in western Greenland because of the long residence time of the ice in the ablation zone (800 years) there; ice flowing through Jakobshavn, by contrast, spends only 20 years in the ablation zone, not enough time for deep, diffusive englacial warming to occur. Examination of the velocity field of the ice sheet indicates that 70% of the ice flux through western Greenland spends insufficient time (200 years or less) in the ablation zone to produce significant englacial warming. Thus, the effects of englacial latent heat transfer may be fairly limited to regions of divergent flow such as Pakitsoq. Ice loss in these regions, which tend to be land-terminating, is dominated by surface melt rather than seaward ice motion, further suggesting that englacial heat transfer may have a lesser effect on the stability of the ice sheet than previously supposed.

  4. Effect of fetch length on latent heat flux data accuracy calculated by Bowen ratio energy balance method

    NASA Astrophysics Data System (ADS)

    Pozníková, Gabriela; Fischer, Milan; Trnka, Miroslav; Orság, Matěj; Kučera, Jiří; Žalud, Zdeněk

    2013-04-01

    Bowen ratio energy balance (BREB) is one of the most widely used indirect methods for deriving latent heat (LE) and sensible heat fluxes. The BREB technique relies on net radiation, ground heat flux, and air temperature and humidity gradients measurements. Whilst the first two mentioned can be practically considered as point measurements, the source area of temperature and humidity gradients is at least one order of magnitudes larger. Therefore, the horizontal, homogeneous and extensive area is necessary prerequisite for correct flux determination by BREB method. An ideal fetch for BREB has been reported to be within 10 to 200 times the height of upper measuring level above zero plane displacement. This broad range is a result of different atmospheric stratifications and surface roughness, but the fetch to height ratio 100:1 has become generally acknowledged as a rule of thumb. In this study, data from four different BREB systems above various covers (two poplar plantations, grassland and turf grass field) will be used to calculate and analyse LE for different fetches. Data were recorded in Domanínek near Bystřice nad Pernštejnem in Czech-Moravian highlands where two BREB systems have measured above poplar plantation and turf grass since summer 2008 until present and two more systems have been placed above grassland and another poplar plantation at the beginning of 2011 and have measured until present time. During the measurements changing wind direction limited the fetch of particular BREB systems on the sites. That is why LE calculated for particular fetch lengths will be split into three categories - fetch classes ("good", "medium", and "bad") according to prevailing wind direction and corresponding fetch. These categories will be delimited using the simple footprint model. Fetches with more than 75% of the measured entities coming from the area of interest will be considered as the "good" ones. The "medium" class will contain fetches with 50-75% of the flux

  5. Spectral retrieval of latent heating profiles from TRMM PR data: comparisons of lookup tables from two- and three-dimensional simulations

    NASA Astrophysics Data System (ADS)

    Shige, Shoichi; Takayabu, Yukari N.; Kida, Satoshi; Tao, Wei-Kuo; Zeng, Xiping; L'Ecuyer, Tristan

    2008-12-01

    The Spectral Latent Heating (SLH) algorithm was developed to estimate latent heating profiles for the TRMM PR. The method uses PR information (precipitation top height, precipitation rates at the surface and melting level, and rain type) to select heating profiles from lookup tables. Lookup tables for the three rain types-convective, shallow stratiform, and anvil rain (deep stratiform with a melting level)-were derived from numerical simulations of tropical cloud systems from the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) utilizing a cloud-resolving model (CRM). The two-dimensional ("2D") CRM was used in the previous studies. The availability of exponentially increasing computer capabilities has resulted in three-dimensional ("3D") CRM simulations for multiday periods becoming increasing prevalent. In this study, we compare lookup tables from the 2D and 3D simulations. The lookup table from 3D simulations results in less agreement between the SLH-retrieved heating and sounding-based one for the South China Sea Monsoon Experiment (SCSMEX). The level of SLH-estimated maximum heating is lower than that of the sounding-derived one. This is explained by the fact that the 3D lookup table produces stronger convective heating and weaker stratiform heating above the melting level that 2D counterpart. Condensate generated in and carried over from the convective region is larger in 3D than in 2D, and condensate that is produced by the stratiform region's own upward motion is smaller in 3D than 2D.

  6. Heat release in the cryogenic system of a superconducting integrated detector and the influence of heat on its operation

    NASA Astrophysics Data System (ADS)

    Kinev, N. V.; Koshelets, V. P.

    2013-03-01

    Heat release in the cryogenic system of a subterahertz-range superconducting integrated detector at ≈4.2 K is studied, and the influence of the released heat on its main characteristics is estimated. The detector chip mounted on a silicon lens is connected to a bias board by aluminum wires 25 μm in diameter, which are fixed by ultrasonic bonding. They are necessary for setting a bias current through the working components of the detector and represent an integral part of the system. The contact resistance between the wires and contact pads of the microchip is measured. The contact resistance is found to considerably exceed the resistance of the aluminum wire and, hence, makes a major contribution to heat release in the system. A "multipoint contact with one wire" technique is suggested. Tests show its efficiency: the contact resistance decreases considerably compared with the standard approach.

  7. Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations

    NASA Astrophysics Data System (ADS)

    Martin, J.; Reichstein, M.

    2012-12-01

    We upscaled FLUXNET observations of carbon dioxide, water and energy fluxes to the global scale using the machine learning technique, Model Tree Ensembles (MTE). We trained MTE to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use. We applied the trained MTEs to generate global flux fields at a 0.5° x 0.5o spatial resolution and a monthly temporal resolution from 1982-2008. Cross-validation analyses revealed good performance of MTE in predicting among-site flux variability with modeling efficiencies (MEf) between 0.64 and 0.84, except for NEE (MEf = 0.32). Performance was also good for predicting seasonal patterns (MEf between 0.84 and 0.89, except for NEE (0.64)). By comparison, predictions of monthly anomalies were weak. Our products are increasingly used to evaluate global land surface models. However, depending on the flux of interest (e.g. gross primary production, terrestrial ecosystem respiration, net ecosystem exchange, evapotranspiration) and the pattern of interest (mean annual map, seasonal cycles, interannual variability, trends) the robustness and uncertainty of these products varies considerably. To avoid pitfalls, this talk also aims at providing an overview of uncertainties associated with these products, and to provide recommendations on the usage for land surface model evaluations. Finally, we present FLUXCOM - an ongoing activity that aims at generating an ensemble of data-driven FLUXNET based products based on diverse approaches.

  8. Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations

    NASA Astrophysics Data System (ADS)

    Jung, Martin; Reichstein, Markus; Margolis, Hank A.; Cescatti, Alessandro; Richardson, Andrew D.; Arain, M. Altaf; Arneth, Almut; Bernhofer, Christian; Bonal, Damien; Chen, Jiquan; Gianelle, Damiano; Gobron, Nadine; Kiely, Gerald; Kutsch, Werner; Lasslop, Gitta; Law, Beverly E.; Lindroth, Anders; Merbold, Lutz; Montagnani, Leonardo; Moors, Eddy J.; Papale, Dario; Sottocornola, Matteo; Vaccari, Francesco; Williams, Christopher

    2011-09-01

    We upscaled FLUXNET observations of carbon dioxide, water, and energy fluxes to the global scale using the machine learning technique, model tree ensembles (MTE). We trained MTE to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use. We applied the trained MTEs to generate global flux fields at a 0.5° × 0.5° spatial resolution and a monthly temporal resolution from 1982 to 2008. Cross-validation analyses revealed good performance of MTE in predicting among-site flux variability with modeling efficiencies (MEf) between 0.64 and 0.84, except for NEE (MEf = 0.32). Performance was also good for predicting seasonal patterns (MEf between 0.84 and 0.89, except for NEE (0.64)). By comparison, predictions of monthly anomalies were not as strong (MEf between 0.29 and 0.52). Improved accounting of disturbance and lagged environmental effects, along with improved characterization of errors in the training data set, would contribute most to further reducing uncertainties. Our global estimates of LE (158 ± 7 J × 1018 yr-1), H (164 ± 15 J × 1018 yr-1), and GPP (119 ± 6 Pg C yr-1) were similar to independent estimates. Our global TER estimate (96 ± 6 Pg C yr-1) was likely underestimated by 5-10%. Hot spot regions of interannual variability in carbon fluxes occurred in semiarid to semihumid regions and were controlled by moisture supply. Overall, GPP was more important to interannual variability in NEE than TER. Our empirically derived fluxes may be used for calibration and evaluation of land surface process models and for exploratory and diagnostic assessments of the biosphere.

  9. Fragmentation of condensed material by isochoric heating and release

    SciTech Connect

    Glenn, L.A.

    1983-03-01

    A model is suggested to describe the mechanics of fragmentation when a liquid or solid body disassembles under intense isochoric heating. The model is based on the concept that surface area created in the fragmentation process is governed by an equilibrium balance of the surface energy and a local inertial or kinetic energy. An expression is derived for the resulting fragment size as a function of the initial size, the specific energy deposited, and thermomechanical properties of the material. The theory is applied to calculate the blanket break-up due to neutron heating in the HYLIFE and Cascade Chamber inertial confinement fusion reactors.

  10. Cold energy release characteristics of an ice/air direct contact heat exchanger

    SciTech Connect

    Ohira, Akiyoshi; Yanadori, Michio; Iwabuchi, Kunihiko; Kimura, Toshikatsu; Tsubota, Yuji

    1998-12-31

    This paper deals with the cold energy release characteristics of an ice/air direct contact heat exchanger in a refined cold energy conveyance system. Characteristics of the outlet temperature, the humidity, and time history of released heat are examined when the initial height of the ice-cube-packed bed in the heat exchanger is changed. The following are the results obtained in these experiments: (1) Inlet air of 30 C is lowered to about 0 C by passing the air through the heat exchanger, and absolute humidity of the outlet air is reduced to about a quarter of that of the inlet air. (2) There is an optimum height of the ice-cube-packed bed for maximizing the amount of cold energy released. (3) This heat exchange method can supply about twice the amount of cold energy released by an ordinary fin-tube-type heat exchanger even if the air velocity in the heat exchanger is reduced to about 0.38 times that of the fin-tube-type heat exchanger.

  11. 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.

  12. The Simulation of the Opposing Fluxes of Latent Heat and CO2 over Various Land-Use Types: Coupling a Gas Exchange Model to a Mesoscale Atmospheric Model

    NASA Astrophysics Data System (ADS)

    Reyers, Mark; Krüger, Andreas; Werner, Christiane; Pinto, Joaquim G.; Zacharias, Stefan; Kerschgens, Michael

    2011-04-01

    A mesoscale meteorological model (FOOT3DK) is coupled with a gas exchange model to simulate surface fluxes of CO2 and H2O under field conditions. The gas exchange model consists of a C3 single leaf photosynthesis sub-model and an extended big leaf (sun/shade) sub-model that divides the canopy into sunlit and shaded fractions. Simulated CO2 fluxes of the stand-alone version of the gas exchange model correspond well to eddy-covariance measurements at a test site in a rural area in the west of Germany. The coupled FOOT3DK/gas exchange model is validated for the diurnal cycle at singular grid points, and delivers realistic fluxes with respect to their order of magnitude and to the general daily course. Compared to the Jarvis-based big leaf scheme, simulations of latent heat fluxes with a photosynthesis-based scheme for stomatal conductance are more realistic. As expected, flux averages are strongly influenced by the underlying land cover. While the simulated net ecosystem exchange is highly correlated with leaf area index, this correlation is much weaker for the latent heat flux. Photosynthetic CO2 uptake is associated with transpirational water loss via the stomata, and the resulting opposing surface fluxes of CO2 and H2O are reproduced with the model approach. Over vegetated surfaces it is shown that the coupling of a photosynthesis-based gas exchange model with the land-surface scheme of a mesoscale model results in more realistic simulated latent heat fluxes.

  13. Heat changes during transient tension responses to small releases in active frog muscle.

    PubMed Central

    Gilbert, S H; Ford, L E

    1988-01-01

    Tension and heat production were measured in frog sartorius muscles in response to small shortening ramps (releases) at high and moderate speed. Transient tension responses to fast releases (0.1 to 0.4 mm in 1 or 4 ms) were similar to the tension transients length-clamped single fibers. Tension time courses during releases at 25 mm/s were like fiber responses calculated from the first two phases of the step responses (Ford et al., 1977). We conclude that similar crossbridge transitions produce tension transients observed in whole muscles and single fibers. Heat was absorbed during rapid tension recovery after fast releases and during the later part of releases at 25 mm/s. Variation of heat absorption with release size was compared with that of crossbridge movement predicted by the Huxley-Simmons hypothesis of force generation (Huxley and Simmons, 1971). Agreement between the two supports the conclusion that heat is absorbed by the crossbridge transitions responsible for rapid tension recovery after release. The results indicate that the entropy change of these transitions is positive. PMID:3265639

  14. The Impact of Heat Release in Turbine Film Cooling

    DTIC Science & Technology

    2008-06-01

    AFIT/GAE/ENY/08-J02 Abstract The Ultra Compact Combustor is a design that integrates a turbine vane into the combustor flow path. Because...of the high fuel-to-air ratio and short combustor flow path, a significant potential exists for unburned fuel to enter the turbine. Using...contemporary turbine cooling vane designs, the injection of oxygen-rich turbine cooling air into a combustor flow containing unburned fuel could result in heat

  15. Study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flows

    NASA Astrophysics Data System (ADS)

    Boltenko, E. A.

    2016-10-01

    The results of the experimental study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flow are presented. The experiments were carried out using electric heated annular channels with one and (or) two heat-release surfaces. For the organization of transit flow on a convex heat-release surface, four longitudinal ribs were installed uniformly at its perimeter. Swirl flow was realized using a capillary wound tightly (without gaps) on the ribs. The ratio between swirl and transit flows in the annular gap was varied by applying longitudinal ribs of different height. The experiments were carried out using a closed-type circulatory system. The experimental data were obtained in a wide range of regime parameters. Both water heated to the temperature less than the saturation temperature and water-steam mixture were fed at the inlet of the channels. For the measurement of the temperature of the heat-release surfaces, chromel-copel thermocouples were used. It was shown that the presence of swirl flow on a convex heatrelease surface led to a significant decrease in critical heat flows (CHF) compared to a smooth surface. To increase CHF, it was proposed to use the interaction of swirl flows of the heat carrier. The second swirl flow was transit flow, i.e., swirl flow with the step equal to infinity. It was shown that CHF values for a channel with swirl and transit flow in all the studied range of regime parameters was higher than CHF values for both a smooth annular channel and a channel with swirl. The empirical ratios describing the dependence of CHF on convex and concave heat-release surfaces of annular channels with swirl and transit flow on the geometrical characteristics of channels and the regime parameters were obtained. The experiments were carried out at the pressure p = 3.0-16.0 MPa and the mass velocity ρw = 250-3000 kg/(m2s).

  16. 75 FR 61521 - NUREG/CR-7010, Cable Heat Release, Ignition, and Spread in Tray Installations During Fire...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... calorimeter to determine their heat of combustion and other properties; to full-scale, in which horizontal... COMMISSION NUREG/CR-7010, Cable Heat Release, Ignition, and Spread in Tray Installations During Fire... Commission has issued for public comment a document entitled: ``NUREG/CR-7010, Cable Heat Release,...

  17. Direct numerical simulations of a reacting mixing layer with chemical heat release

    NASA Technical Reports Server (NTRS)

    Mcmurtry, P. A.; Jou, W.-H.; Metcalfe, R. W.; Riley, J. J.

    1985-01-01

    In order to study the coupling between chemical heat release and fluid dynamics, direct numerical simulations of a chemically reacting mixing layer with heat release are performed. The fully compressible equations as well as an approximate set of equations that is asymptotically valid for low-Mach-number flows are treated. These latter equations have the computational advantage that high-frequency acoustic waves have been filtered out, allowing much larger time steps to be taken in the numerical solution procedure. A detailed derivation of these equations along with an outline of the numerical solution technique is given. Simulation results indicate that the rate of chemical product formed, the thickness of the mixing layer, and the amount of mass entrained into the layer all decrease with increasing rates of heat release.

  18. Modeling drug release from functionalized magnetic nanoparticles actuated by non-heating low frequency magnetic field

    NASA Astrophysics Data System (ADS)

    Golovin, Y.; Golovin, D.; Klyachko, N.; Majouga, A.; Kabanov, A.

    2017-02-01

    Various plausible acceleration mechanisms of drug release from nanocarriers composed of a single-domain magnetic nanoparticle core with attached long macromolecule chains activated by low frequency non-heating alternating magnetic field (AMF) are discussed. The most important system characteristics affecting the AMF exposure impact are determined. Impact of several reasonable mechanisms is estimated analytically or obtained using numerical modeling. Some conditions providing manifold release acceleration as a result from exposure in AMF are found.

  19. Nucleation of cracks in a perforated heat-releasing material with temperature-dependent elastic properties

    NASA Astrophysics Data System (ADS)

    Vagari, A. R.; Mirsalimov, V. M.

    2012-07-01

    A mathematical model of crack nucleation in a perforated heat-releasing material attenuated by a biperiodic system of cooling cylindrical channels with a circular cross section is constructed. Solving the problem of equilibrium of an isotropic perforated heat-releasing material with temperature-dependent properties containing nucleating cracks is reduced to solving systems of algebraic and nonlinear singular integral equations with a Cauchy-type kernel. The forces in crack nucleation regions are found by using the solution of these equations. The condition of crack emergence is formulated with allowance for the criterion of ultimate stretching of bonds in the material.

  20. The Effect of Spray Initial Conditions on Heat Release and Emissions in LDI CFD Calculations

    NASA Technical Reports Server (NTRS)

    Iannetti, Anthony C.; Liu, Nan-Suey; Davoudzadeh, Farhad

    2008-01-01

    The mass and velocity distribution of liquid spray has a primary effect on the combustion heat release process. This heat release process then affects emissions like nitrogen oxides (NOx) and carbon monoxide (CO). Computational Fluid Dynamics gives the engineer insight into these processes, but various setup options exist (number of droplet groups, and initial droplet temperature) for spray initial conditions. This paper studies these spray initial condition options using the National Combustion Code (NCC) on a single swirler lean direct injection (LDI) flame tube. Using laminar finite rate chemistry, comparisons are made against experimental data for velocity measurements, temperature, and emissions (NOx, CO).

  1. Americium and plutonium release behavior from irradiated mixed oxide fuel during heating

    NASA Astrophysics Data System (ADS)

    Sato, I.; Suto, M.; Miwa, S.; Hirosawa, T.; Koyama, S.

    2013-06-01

    The release behavior of Pu and Am was investigated under the reducing atmosphere expected in sodium cooled fast reactor severe accidents. Irradiated Pu and U mixed oxide fuels were heated at maximum temperatures of 2773 K and 3273 K. EPMA, γ-ray spectrometry and α-ray spectrometry for released and residual materials revealed that Pu and Am can be released more easily than U under the reducing atmosphere. The respective release rate coefficients for Pu and Am were obtained as 3.11 × 10-4 min-1 and 1.60 × 10-4 min-1 at 2773 K under the reducing atmosphere with oxygen partial pressure less than 0.02 Pa. Results of thermochemical calculations indicated that the main released chemical forms would likely be PuO for Pu and Am for Am under quite low oxygen partial pressure.

  2. Interaction of Two Micro-slot Flames: Heat Release Rate and Flame Shape

    NASA Astrophysics Data System (ADS)

    Kuwana, K.; Kato, S.; Kosugi, A.; Hirasawa, T.; Nakamura, Y.

    2014-11-01

    This paper studies the interaction between two identical micro-slot diffusion flames. Here, we define a micro-slot flame as a slot flame of which the slot width is less than about 1 mm. Because of its smallness, a micro-slot flame has a high heating density and can be used as a small heat source. However, the heat release rate of a single micro-slot flame is limited, and therefore, multiple micro-slot flames may be used to increase total heat release rate. As a first step, this paper considers a situation in which two micro-slot flames are used with certain burner spacing. When two diffusion flames are placed closely, flame shape changes from that of an isolated flame. Studying such flame shape change and resultant change in total heat release rate is the topic of this paper. Experiment is conducted and total heat release rate is measured by integrating CH* chemiluminescence recorded using a CCD camera and an optical filter of the wavelength of 430 nm. Two different burner materials, copper and glass, are tested to study the effect of heat loss to burners. An analytical model is applied to predict flame shape. In addition to the classical Burke-Schumann assumptions, two slot flames are modeled as line sources with zero width, enabling a simple analytical solution for the critical burner spacing at which two flames touch each other. The critical burner spacing is a key parameter that characterizes the interaction between two micro-slot flames. Computational fluid dynamics (CFD) simulations are then conducted to test the validity of the present theory. CFD results are favorably compared with the theoretical prediction.

  3. Critical heat flux and dynamics of boiling in nanofluids at stepwise heat release

    NASA Astrophysics Data System (ADS)

    Moiseev, M. I.; Kuznetsov, D. V.

    2016-10-01

    In this paper results of an experimental study on critical heat flux and dynamics of boiling crisis onset in nanofluids at stepwise heat generation are presented. Freon R21 with three types of nanoparticles - SiO2, Cu and Al2O3 was used as test fluid. Critical heat fluxes and temperatures of boiling initiation were obtained. It was shown that the addition of nanoparticles increased CHF at stepwise heat generation by up to 21%. Under conditions of the experiment transition to film boiling occurred via evaporation fronts. Data on propagation velocity and structure of evaporation fronts were obtained; the spectral analysis of fluctuations of the evaporation front interface was carried out. The characteristic frequencies and amplitudes of interface fluctuations were determined depending on the velocity of evaporation front propagation. It was shown that the addition of nano-sized particles significantly affects development of interface instability and increases the front velocity.

  4. Impact of Dissociation and Sensible Heat Release on Pulse Detonation and Gas Turbine Engine Performance

    NASA Technical Reports Server (NTRS)

    Povinelli, Louis A.

    2001-01-01

    A thermodynamic cycle analysis of the effect of sensible heat release on the relative performance of pulse detonation and gas turbine engines is presented. Dissociation losses in the PDE (Pulse Detonation Engine) are found to cause a substantial decrease in engine performance parameters.

  5. Coupling between entropy and unsteady heat release in a thermoacoustic system with a mean flow

    NASA Astrophysics Data System (ADS)

    Li, Lei; Zhao, Dan

    2016-11-01

    In this work, the coupling between entropy and unsteady heat release in a one dimensional duct in the presence of a mean flow is considered. As acoustic disturbances impinge on a compact heat source enclosed in the duct, entropy disturbances are generated. The transfer function between the generated entropy waves and oncoming flow velocity fluctuations is deduced by conducting order analysis of the linearized governing equations. The effects of the mean flow are emphasized for different forms of unsteady heat release model. It is shown that there is a strong coupling between entropy, heat release, mean flow and acoustic impedance at the heat source. To validate our theoretical analysis, numerical investigation is conducted by using a low order model. Comparing the theoretical and the low order model's results reveals that a good agreement is observed. It is found that when the mean flow Mach number is not negligible, the term of O(M1) in the identified entropy transfer function is as important as that of O(M0). Neglecting the term of O(M1) may lead to wrong prediction of the entropy waves produced in the system.

  6. Living donor and recipient screening for latent tuberculosis infection by tuberculin skin test and interferon-gamma releasing assay in a country with an intermediate burden of tuberculosis.

    PubMed

    Moon, Song Mi; Park, In-Ah; Kim, Sun-Mi; Park, Su-Jin; Jung, Joo Hee; Kim, Young Hoon; Park, Jae Berm; Hong, Bumsik; Lee, Sang-Oh; Choi, Sang-Ho; Kim, Yang Soo; Woo, Jun Hee; Park, Su-Kil; Lee, Sang Koo; Park, Jung Sik; Han, Duck Jong; Kim, Sung-Han

    2013-10-01

    There are few data on donor screening for latent tuberculosis infection (LTBI) using the tuberculin skin test (TST) and interferon-gamma releasing assay (IGRA). In South Korea, most renal allografts involve living donors (average, 80%). Hence, we have an opportunity to evaluate donor and recipient screening for LTBI by TST and IGRA. All donors and recipients admitted for kidney transplantation during a 20-month period were evaluated prospectively by using TST and Mycobacterium tuberculosis-specific enzyme-linked immunosorbent spot (ELISPOT) assay. The study population consisted of 205 living donor-recipient pairs (≥16 years) including 15 (7%) who yielded indeterminate donor or recipient ELISPOT results. Of the 205 donors, 63 (31%) gave a positive TST ≥5 mm, 33 (16%) a positive TST ≥10 mm, and 96 (47%) a positive ELISPOT. Of the 205 recipients, 9 (5%) gave a positive TST ≥5 mm, 3 (2%) a positive TST ≥10 mm, and 79 (39%) had a positive ELISPOT. Of the 205 donor-recipient pairs, only 59 (29%) gave negative donor and recipient ELISPOT results and 139 (68%) negative donor and recipient TSTs (<5 mm) (P < 0.001). One third of donor-recipient pairs tends to be positive in the TST, and two thirds of the donor-recipient pairs tends to be positive in the ELISPOT. Given the high positive rate of LTBI obtained by screening donors, further studies on the clinical value of solid organ transplant donors with positive TST or ELISPOT and health economics analysis in countries with intermediate burden of TB are needed for policy decisions on isoniazid (INH) prophylaxis.

  7. The Clinical Usefulness of Tuberculin Skin Test versus Interferon-Gamma Release Assays for Diagnosis of Latent Tuberculosis in HIV Patients: A Meta-Analysis

    PubMed Central

    Ayubi, Erfan; Doosti-Irani, Amin; Sanjari Moghaddam, Ali; Sani, Mohadeseh; Nazarzadeh, Milad; Mostafavi, Ehsan

    2016-01-01

    Background Accurate diagnosis of latent tuberculosis infection (LTBI) is becoming increasingly concerning due to the increasing the HIV epidemic, which have increased the risk for reactivation to active tuberculosis (TB) infection. LTBI is diagnosed by tuberculin skin test (TST) and interferon-gamma release assays (IGRAs). Objectives The aim of the present study was to conduct a meta-analysis of published papers on the agreement (kappa) between TST and QuantiFERON-TB Gold In-Tube (QFT-GIT) tests for diagnosis of LTBI in HIV patient. Methods Electronic databases including PubMed/Medline, Elsevier/Scopus and Embase/Ovid were reviewed up Jan. 2016. We performed a random effect model meta-analysis for estimation of pooled Kappa between the two methods of diagnosis. Meta regression was used for assessing potential heterogeneity and Egger’s test was used for assessing small study effect and publication bias. Results The initial search strategy produced 6744 records. Of them, 23 cross-sectional studies met the inclusion criteria and 20 studies entered in meta-analysis. The pooled kappa was and prevalence-adjusted and bias-adjusted kappa (PABAK) were 0.37 (95% CI: 0.28, 0.46) and 0.59 (0.49, 0.69). The discordance of TST-/QFT-GIT+ was more than TST+/QFT-GIT-. Kappa estimate between two tests was linearly associated with age and prevalence index and inversely associated with bias index. Conclusion Fair agreement between TST and QFT-GIT makes it difficult to know whether TST is as useful as the QFT-GIT in HIV-infected patients. The higher discordance of TST-/QFT-GIT+ in compared to TST+/QFT-GIT- can induce the higher sensitivity of QFT-GIT for diagnosis LTBI in HIV patients. Disagreement between two tests can be influenced by error in measurements and prevalence of HIV. PMID:27622293

  8. Key Role of Effector Memory CD4+ T Lymphocytes in a Short-Incubation Heparin-Binding Hemagglutinin Gamma Interferon Release Assay for the Detection of Latent Tuberculosis

    PubMed Central

    Wyndham-Thomas, Chloé; Corbière, Véronique; Dirix, Violette; Smits, Kaatje; Domont, Fanny; Libin, Myriam; Loyens, Marc; Locht, Camille

    2014-01-01

    The treatment of latent tuberculosis infection (LTBI) in target populations is one of the current WHO strategies for preventing active tuberculosis (TB) infection and reducing the Mycobacterium tuberculosis reservoir. Therefore, powerful LTBI screening tools are indispensable. A gamma interferon release assay (IGRA) in response to the stimulation of peripheral blood mononuclear cells by the latency antigen native heparin-binding hemagglutinin (nHBHA-IGRA) has proven its potential for this purpose. We have evaluated its possible optimization through a reduction of incubation time from 96 to 24 h, while compensating for this by adding interleukin 7 (IL-7) to the medium. We have also investigated the phenotypes of the gamma interferon (IFN-γ)-producing cells after both short and long incubation times. One hundred thirty-one nonimmunocompromised patients were recruited from 3 Brussels-based university hospitals. They were divided into 1 of 4 subgroups according to their M. tuberculosis infection status (LTBI, TB infection, undetermined M. tuberculosis infection status, and noninfected controls). The novel 24-h nHBHA-IGRA was performed for all subjects, and a simultaneous 96-h classical HBHA-IGRA was performed for 79 individuals. The results showed a good correlation between the two tests, and the novel 24-h nHBHA-IGRA maintained the principal advantages of the classical test, namely, a high specificity for LTBI diagnosis, an absence of interference of Mycobacterium bovis BCG vaccination during infancy, and a relative discrimination between LTBI and TB infection. Whereas the commercialized IGRAs show a greater sensitivity for recent than for remote M. tuberculosis infections, the 24-h nHBHA-IGRA appears to have comparable diagnostic powers for recent and remote LTBI. The IFN-γ detected by the 24-h nHBHA-IGRA was mainly secreted by effector memory CD4+ T lymphocytes, a finding suggestive of continuous HBHA presentation during latency. PMID:24391135

  9. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    SciTech Connect

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heat release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  10. Heating Structures Derived from Satellite

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Adler, R.; Haddad, Z.; Hou, A.; Kakar, R.; Krishnamurti, T. N.; Kummerow, C.; Lang, S.; Meneghini, R.; Olson, W.

    2004-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent-heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. The Tropical Rainfall Measuring Mission (TRMM), a joint U.S./Japan space project, was launched in November 1997. It provides an accurate measurement of rainfall over the global tropics which can be used to estimate the four-dimensional structure of latent heating over the global tropics. The distributions of rainfall and inferred heating can be used to advance our understanding of the global energy and water cycle. This paper describes several different algorithms for estimating latent heating using TRMM observations. The strengths and weaknesses of each algorithm as well as the heating products are also discussed. The validation of heating products will be exhibited. Finally, the application of this heating information to global circulation and climate models is presented.

  11. Impact of Cloud Model Microphysics on Passive Microwave Retrievals of Cloud Properties. Part II: Uncertainty in Rain, Hydrometeor Structure, and Latent Heating Retrievals

    NASA Astrophysics Data System (ADS)

    Seo, Eun-Kyoung; Biggerstaff, Michael I.

    2006-07-01

    The impact of model microphysics on the retrieval of cloud properties based on passive microwave observations was examined using a three-dimensional, nonhydrostatic, adaptive-grid cloud model to simulate a mesoscale convective system over ocean. Two microphysical schemes, based on similar bulk two-class liquid and three-class ice parameterizations, were used to simulate storms with differing amounts of supercooled cloud water typical of both the tropical oceanic environment, in which there is little supercooled cloud water, and midlatitude continental environments in which supercooled cloud water is more plentiful. For convective surface-level rain rates, the uncertainty varied between 20% and 60% depending on which combination of passive and active microwave observations was used in the retrieval. The uncertainty in surface rain rate did not depend on the microphysical scheme or the parameter settings except for retrievals over stratiform regions based on 85-GHz brightness temperatures TB alone or 85-GHz TB and radar reflectivity combined. In contrast, systematic differences in the treatment of the production of cloud water, cloud ice, and snow between the parameterization schemes coupled with the low correlation between those properties and the passive microwave TB examined here led to significant differences in the uncertainty in retrievals of those cloud properties and latent heating. The variability in uncertainty of hydrometeor structure and latent heating associated with the different microphysical parameterizations exceeded the inherent variability in TB cloud property relations. This was true at the finescales of the cloud model as well as at scales consistent with satellite footprints in which the inherent variability in TB cloud property relations are reduced by area averaging.

  12. Clean Photothermal Heating and Controlled Release from Near-Infrared Dye Doped Nanoparticles without Oxygen Photosensitization.

    PubMed

    Guha, Samit; Shaw, Scott K; Spence, Graeme T; Roland, Felicia M; Smith, Bradley D

    2015-07-21

    The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of (1)O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive (1)O2, leading to bleaching of the dye and also decomposition of coencapsulated payload such as the drug doxorubicin. Croc dye was especially useful as a photothermal agent for laser-controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water-soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications.

  13. Combustion heat release effects on asymmetric vortex shedding from bluff bodies

    NASA Astrophysics Data System (ADS)

    Cross, Caleb Nathaniel

    2011-07-01

    This thesis describes an investigation of oscillatory combustion processes due to vortex shedding from bluff body flame holders. The primary objective of this study was to elucidate the influence of combustion process heat release upon the Benard-von Karman (BVK) instability in reacting bluff body wakes. For this purpose, spatial and temporal heat release distributions in bluff body-stabilized combustion of liquid Jet-A fuel with high-temperature, vitiated air were characterized over a wide range of operating conditions. Two methods of fuel injection were investigated. In the first method, referred to as close-coupled fuel injection, the fuel was supplied via discrete liquid jets injected perpendicular to the cross-flowing air stream just upstream of the bluff body trailing edge, thereby limiting fuel and air mixing prior to burning. The fuel was introduced well upstream (˜0.5 m) of the bluff body in the second fuel injection mode, resulting in a well-evaporated and mixed reactants stream. The resulting BVK heat release dynamics were compared between these fuel injection modes in order to investigate their dependence upon the spatial distributions of fuel-air ratio and heat release in the reacting wake. When close-coupled fuel injection was used, the BVK heat release dynamics increased in amplitude with increasing global equivalence ratio, reaching a maximum just before globally rich blow out of the combustion process occurred. This was due to a decrease in fuel entrainment into the near-wake as the fuel spray penetrated further into the cross-flow, which reduced the local heat release and equivalence ratio (indicated by CH* and C2*/CH* chemiluminescence, respectively). As a result, the density gradient across the near-wake reaction zone decreased, resulting in less damping of vorticity due to dilatation. In addition, unburned reactants were entrained into the recirculation zone due to the injection of discrete liquid fuel jets in close proximity to the wake. This

  14. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    DOE PAGES

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heatmore » release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  15. Combustion instability and active control: Alternative fuels, augmentors, and modeling heat release

    NASA Astrophysics Data System (ADS)

    Park, Sammy Ace

    Experimental and analytical studies were conducted to explore thermo-acoustic coupling during the onset of combustion instability in various air-breathing combustor configurations. These include a laboratory-scale 200-kW dump combustor and a 100-kW augmentor featuring a v-gutter flame holder. They were used to simulate main combustion chambers and afterburners in aero engines, respectively. The three primary themes of this work includes: 1) modeling heat release fluctuations for stability analysis, 2) conducting active combustion control with alternative fuels, and 3) demonstrating practical active control for augmentor instability suppression. The phenomenon of combustion instabilities remains an unsolved problem in propulsion engines, mainly because of the difficulty in predicting the fluctuating component of heat release without extensive testing. A hybrid model was developed to describe both the temporal and spatial variations in dynamic heat release, using a separation of variables approach that requires only a limited amount of experimental data. The use of sinusoidal basis functions further reduced the amount of data required. When the mean heat release behavior is known, the only experimental data needed for detailed stability analysis is one instantaneous picture of heat release at the peak pressure phase. This model was successfully tested in the dump combustor experiments, reproducing the correct sign of the overall Rayleigh index as well as the remarkably accurate spatial distribution pattern of fluctuating heat release. Active combustion control was explored for fuel-flexible combustor operation using twelve different jet fuels including bio-synthetic and Fischer-Tropsch types. Analysis done using an actuated spray combustion model revealed that the combustion response times of these fuels were similar. Combined with experimental spray characterizations, this suggested that controller performance should remain effective with various alternative fuels

  16. Residual resistance of 2D and 3D structures and Joule heat release.

    PubMed

    Gurevich, V L; Kozub, V I

    2011-06-22

    We consider a residual resistance and Joule heat release in 2D nanostructures as well as in ordinary 3D conductors. We assume that elastic scattering of conduction electrons by lattice defects is predominant. Within a rather intricate situation in such systems we discuss in detail two cases. (1) The elastic scattering alone (i.e. without regard of inelastic mechanisms of scattering) leads to a transition of the mechanical energy (stored by the electrons under the action of an electric field) into heat in a traditional way. This process can be described by the Boltzmann equation where it is possible to do the configuration averaging over defect positions in the electron-impurity collision term. The corresponding conditions are usually met in metals. (2) The elastic scattering can be considered with the help of the standard electron-impurity collision integral only in combination with some additional averaging procedure (possibly including inelastic scattering or some mechanisms of electron wavefunction phase destruction). This situation is typical for degenerate semiconductors with a high concentration of dopants and conduction electrons. Quite often, heat release can be observed via transfer of heat to the lattice, i.e. via inelastic processes of electron-phonon collisions and can take place at distances much larger than the size of the device. However, a direct heating of the electron system can be registered too by, for instance, local measurements of the current noise or direct measurement of an electron distribution function.

  17. Models to predict both sensible and latent heat transfer in the respiratory tract of Morada Nova sheep under semiarid tropical environment.

    PubMed

    Fonseca, Vinícius Carvalho; Saraiva, Edilson Paes; Maia, Alex Sandro Campos; Nascimento, Carolina Cardoso Nagib; da Silva, Josinaldo Araújo; Pereira, Walter Esfraim; Filho, Edgard Cavalcanti Pimenta; Almeida, Maria Elivânia Vieira

    2016-10-10

    The aim of this study was to build a prediction model both sensible and latent heat transfer by respiratory tract for Morada Nova sheep under field conditions in a semiarid tropical environment, using easily measured physiological and environmental parameters. Twelve dry Morada Nova ewes with an average of 3 ± 1.2 years old and average body weight of 32.76 ± 3.72 kg were used in a Latin square design 12 × 12 (12 days of records and 12 schedules). Tidal volume, respiratory rate, expired air temperature, and partial vapor pressure of the expired air were obtained from the respiratory facial mask and using a physiological measurement system. Ewes were evaluated from 0700 to 1900 h in each day under shade. A simple nonlinear model to estimate tidal volume as a function of respiratory rate was developed. Equation to estimate the expired air temperature was built, and the ambient air temperature was the best predictor together with relative humidity and ambient vapor pressure. In naturalized Morada Nova sheep, respiratory convection seems to be a mechanism of heat transfer of minor importance even under mild air temperature. Evaporation from the respiratory system increased together with ambient air temperature. At ambient air temperature, up to 35 °C respiratory evaporation accounted 90 % of the total heat lost by respiratory system, on average. Models presented here allow to estimate the heat flow from the respiratory tract for Morada Nova sheep bred in tropical region, using easily measured physiological and environmental traits as respiratory rate, ambient air temperature, and relative humidity.

  18. Models to predict both sensible and latent heat transfer in the respiratory tract of Morada Nova sheep under semiarid tropical environment

    NASA Astrophysics Data System (ADS)

    Fonseca, Vinícius Carvalho; Saraiva, Edilson Paes; Maia, Alex Sandro Campos; Nascimento, Carolina Cardoso Nagib; da Silva, Josinaldo Araújo; Pereira, Walter Esfraim; Filho, Edgard Cavalcanti Pimenta; Almeida, Maria Elivânia Vieira

    2016-10-01

    The aim of this study was to build a prediction model both sensible and latent heat transfer by respiratory tract for Morada Nova sheep under field conditions in a semiarid tropical environment, using easily measured physiological and environmental parameters. Twelve dry Morada Nova ewes with an average of 3 ± 1.2 years old and average body weight of 32.76 ± 3.72 kg were used in a Latin square design 12 × 12 (12 days of records and 12 schedules). Tidal volume, respiratory rate, expired air temperature, and partial vapor pressure of the expired air were obtained from the respiratory facial mask and using a physiological measurement system. Ewes were evaluated from 0700 to 1900 h in each day under shade. A simple nonlinear model to estimate tidal volume as a function of respiratory rate was developed. Equation to estimate the expired air temperature was built, and the ambient air temperature was the best predictor together with relative humidity and ambient vapor pressure. In naturalized Morada Nova sheep, respiratory convection seems to be a mechanism of heat transfer of minor importance even under mild air temperature. Evaporation from the respiratory system increased together with ambient air temperature. At ambient air temperature, up to 35 °C respiratory evaporation accounted 90 % of the total heat lost by respiratory system, on average. Models presented here allow to estimate the heat flow from the respiratory tract for Morada Nova sheep bred in tropical region, using easily measured physiological and environmental traits as respiratory rate, ambient air temperature, and relative humidity.

  19. Heat produces uteroplacental circulatory disturbance in pregnant rats through action of corticotropin releasing hormone (CRH).

    PubMed

    Nakamura, H; Nagase, H; Ogino, K; Hatta, K; Matsuzaki, I

    2000-01-01

    There is some evidence showing an existence of corticotropin releasing hormone (CRH) and opioid peptides, including beta-endorphin (betaEP), in human placenta, whereas physiological roles of the placental peptides in response to stress remain to be elucidated. To clarify the involvement of CRH and opioid system in the uteroplacental circulation in the pregnant rats exposed to heat, we examined the effects of heat and intravenous administration of CRH receptor antagonist alpha-helical CRH (9-41) on the uteroplacental blood flow, as well as blood CRH, and blood and placental betaEP in pregnant rats. Heat did not change uterine blood flow in virgin rats, but reduced uteroplacental blood flow in pregnant rats. The reduced uteroplacental blood flow induced by heat in pregnant rats was reversed by the administration of alpha-helical CRH. Independent of the status of pregnancy, heat increased blood CRH, which was not reversed by alpha-helical CRH. Although heat did not change placental betaEP, alpha-helical CRH reduced blood and placenta betaEP in pregnant rats. These results suggest that the uteroplacental circulatory disturbance caused by heat is mediated by CRH, possibly through the involvement of CRH receptor in rat placenta. The placental opioid system seems unlikely to be involved in the mediation of uteroplacental circulation.

  20. Interferon Gamma Release Assays for the Diagnosis of Latent TB Infection in HIV-Infected Individuals in a Low TB Burden Country

    PubMed Central

    Ní Cheallaigh, Clíona; Fitzgerald, Ian; Grace, Jacinta; Jagjit Singh, Gurmit; El-Eraki, Nahla; Gibbons, Noel; Keane, Joseph; Rogers, Thomas R.; Clarke, Susan; Bergin, Colm

    2013-01-01

    Background Interferon gamma release assays (IGRAs) are used to diagnose latent tuberculosis infection. Two IGRAs are commercially available: the Quantiferon TB Gold In Tube (QFT-IT) and the T-SPOT.TB. There is debate as to which test to use in HIV+ individuals. Previous publications from high TB burden countries have raised concerns that the sensitivity of the QFT-IT assay, but not the T-SPOT.TB, may be impaired in HIV+ individuals with low CD4+ T-cell counts. We sought to compare the tests in a low TB burden setting. Methodology/Principal Findings T-SPOT.TB, QFT-IT, and tuberculin skin tests (TST) were performed in HIV infected individuals. Results were related to patient characteristics. McNemar’s test, multivariate regression and correlation analysis were carried out using SPSS (SPSS Inc). 256 HIV infected patients were enrolled in the study. The median CD4+ T-cell count was 338 cells/µL (range 1–1328). 37 (14%) patients had a CD4+ T-cell count of <100 cells/µL. 46/256 (18% ) of QFT-IT results and 28/256 (11%) of T-SPOT.TB results were positive. 6 (2%) of QFT-IT and 18 (7%) of T-SPOT.TB results were indeterminate. An additional 9 (4%) of T-SPOT.TB results were unavailable as tests were not performed due to insufficient cells or clotting of the sample. We found a statistically significant association between lower CD4+ T-cell count and negative QFT-IT results (OR 1.055, p = 0.03), and indeterminate/unavailable T-SPOT.TB results (OR 1.079, p = 0.02). Conclusions/Significance In low TB prevalence settings, the QFT-IT yields more positive and fewer indeterminate results than T-SPOT.TB. Negative results on the QFT-IT and indeterminate/unavailable results on the T-SPOT.TB were more common in individuals with low CD4+ T-cell counts. PMID:23382842

  1. The Significance of Sensitive Interferon Gamma Release Assays for Diagnosis of Latent Tuberculosis Infection in Patients Receiving Tumor Necrosis Factor-α Antagonist Therapy

    PubMed Central

    Jung, Yu Jung; Woo, Hye In; Jeon, Kyeongman; Koh, Won-Jung; Jang, Dong Kyoung; Cha, Hoon Suk; Koh, Eun Mi; Lee, Nam Yong; Kang, Eun-Suk

    2015-01-01

    Objective We compared two interferon gamma release assays (IGRAs), QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB, for diagnosis of latent tuberculosis infection (LTBI) in patients before and while receiving tumor necrosis factor (TNF)-α antagonist therapy. This study evaluated the significance of sensitive IGRAs for LTBI screening and monitoring. Methods Before starting TNF-α antagonist therapy, 156 consecutive patients with rheumatic diseases were screened for LTBI using QFT-GIT and T-SPOT.TB tests. According to our study protocol, QFT-GIT-positive patients received LTBI treatment. Patients positive by any IGRAs were subjected to follow-up IGRA tests after completing LTBI-treatment and/or during TNF-α antagonist therapy. Results At the initial LTBI screening, 45 (28.9%) and 70 (44.9%) patients were positive by QFT-GIT and T-SPOT.TB, respectively. The agreement rate between IGRA results was 78.8% (k = 0.56; 95% confidence interval [95% CI] = 0.43 to 0.68). Of 29 patients who were positive only by T-SPOT.TB in the initial screening, 83% (19/23) were persistently positive by T-SPOT.TB, while QFT-GIT testing showed that 36% (9/25) had conversion during TNF-α antagonist therapy. By the end of the follow-up period (218 to 1,264 days), four patients (4/137, 2.9%) developed active tuberculosis (TB) diseases during receiving TNF-α antagonist therapy. Among them, one was Q-T+, one was Q+T-, and the remaining two were Q-T- at the initial screening (Q, QuantiFERON-TB Gold In-Tube; T, T-SPOT.TB; +, positive; -, negative). Two (2/4, 50%) patients with TB reactivation had at least one prior risk factor consistent with previous TB infection. Conclusion This study demonstrated the need to capitalize on sensitive IGRAs to monitor for LTBI in at-risk patients for a more sensitive diagnosis in countries with an intermediate TB burden. PMID:26474294

  2. Screening for latent tuberculosis in Norwegian health care workers: high frequency of discordant tuberculin skin test positive and interferon-gamma release assay negative results

    PubMed Central

    2013-01-01

    Background Tuberculosis (TB) presents globally a significant health problem and health care workers (HCW) are at increased risk of contracting TB infection. There is no diagnostic gold standard for latent TB infection (LTBI), but both blood based interferon-gamma release assays (IGRA) and the tuberculin skin test (TST) are used. According to the national guidelines, HCW who have been exposed for TB should be screened and offered preventive anti-TB chemotherapy, but the role of IGRA in HCW screening is still unclear. Methods A total of 387 HCW working in clinical and laboratory departments in three major hospitals in the Western region of Norway with possible exposure to TB were included in a cross-sectional study. The HCW were asked for risk factors for TB and tested with TST and the QuantiFERON®TB Gold In-Tube test (QFT). A logistic regression model analyzed the associations between risk factors for TB and positive QFT or TST. Results A total of 13 (3.4%) demonstrated a persistent positive QFT, whereas 214 (55.3%) had a positive TST (≥ 6 mm) and 53 (13.7%) a TST ≥ 15 mm. Only ten (4.7%) of the HCW with a positive TST were QFT positive. Origin from a TB-endemic country was the only risk factor associated with a positive QFT (OR 14.13, 95% CI 1.37 - 145.38, p = 0.026), whereas there was no significant association between risk factors for TB and TST ≥ 15 mm. The five HCW with an initial positive QFT that retested negative all had low interferon-gamma (IFN-γ) responses below 0.70 IU/ml when first tested. Conclusions We demonstrate a low prevalence of LTBI in HCW working in hospitals with TB patients in our region. The “IGRA-only” seems like a desirable screening strategy despite its limitations in serial testing, due to the high numbers of discordant TST positive/IGRA negative results in HCW, probably caused by BCG vaccination or boosting due to repetitive TST testing. Thus, guidelines for TB screening in HCW should be updated in order to

  3. Comparison of Interferon-γ Release Assay to Two Cut-Off Points of Tuberculin Skin Test to Detect Latent Mycobacterium tuberculosis Infection in Primary Health Care Workers

    PubMed Central

    de Souza, Fernanda Mattos; do Prado, Thiago Nascimento; Pinheiro, Jair dos Santos; Peres, Renata Lyrio; Lacerda, Thamy Carvalho; Loureiro, Rafaela Borge; Carvalho, Jose Américo; Fregona, Geisa; Dias, Elias Santos; Cosme, Lorrayne Beliqui; Rodrigues, Rodrigo Ribeiro; Riley, Lee Wood; Maciel, Ethel Leonor Noia

    2014-01-01

    Background An interferon-γ release assay, QuantiFERON-TB (QFT) test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Here, we compared the performance of QFT with tuberculin skin test (TST) measured at two different cut-off points among primary health care work (HCW) in Brazil. Methods A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points. Results We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31), and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22). We investigated possible factors of discordance of TST vs QFT. Compared to the TST−/QFT− group, risk factors for discordance in the TST+/QFT− group with TST cut-off of ≥5 mm included age between 41–45 years [OR = 2.70; CI 95%: 1.32–5.51] and 46–64 years [OR = 2.04; CI 95%: 1.05–3.93], BCG scar [OR = 2.72; CI 95%: 1.40–5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09–4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03–4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01–2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05–2.62], were significantly associated with the TST+/QFT− group. No statistically significant associations were found among the TST−/QFT+ discordant group with either TST cut-off value. Conclusions Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed. PMID:25137040

  4. Activated platelets release sphingosine 1-phosphate and induce hypersensitivity to noxious heat stimuli in vivo

    PubMed Central

    Weth, Daniela; Benetti, Camilla; Rauch, Caroline; Gstraunthaler, Gerhard; Schmidt, Helmut; Geisslinger, Gerd; Sabbadini, Roger; Proia, Richard L.; Kress, Michaela

    2015-01-01

    At the site of injury activated platelets release various mediators, one of which is sphingosine 1-phosphate (S1P). It was the aim of this study to explore whether activated human platelets had a pronociceptive effect in an in vivo mouse model and whether this effect was based on the release of S1P and subsequent activation of neuronal S1P receptors 1 or 3. Human platelets were prepared in different concentrations (105/μl, 106/μl, 107/μl) and assessed in mice with different genetic backgrounds (WT, S1P1fl/fl, SNS-S1P1−/−, S1P3−/−). Intracutaneous injections of activated human platelets induced a significant, dose-dependent hypersensitivity to noxious thermal stimulation. The degree of heat hypersensitivity correlated with the platelet concentration as well as the platelet S1P content and the amount of S1P released upon platelet activation as measured with LC MS/MS. Despite the significant correlations between S1P and platelet count, no difference in paw withdrawal latency (PWL) was observed in mice with a global null mutation of the S1P3 receptor or a conditional deletion of the S1P1 receptor in nociceptive primary afferents. Furthermore, neutralization of S1P with a selective anti-S1P antibody did not abolish platelet induced heat hypersensitivity. Our results suggest that activated platelets release S1P and induce heat hypersensitivity in vivo. However, the platelet induced heat hypersensitivity was caused by mediators other than S1P. PMID:25954148

  5. The heat released during catalytic turnover enhances the diffusion of an enzyme

    DOE PAGES

    Riedel, Clement; Gabizon, Ronen; Wilson, Christian A. M.; ...

    2014-12-10

    Recent studies have shown that the diffusivity of enzymes increases in a substrate-dependent manner during catalysis. Although this observation has been reported and characterized for several different systems, the precise origin of this phenomenon is unknown. Calorimetric methods are often used to determine enthalpies from enzyme-catalysed reactions and can therefore provide important insight into their reaction mechanisms. The ensemble averages involved in traditional bulk calorimetry cannot probe the transient effects that the energy exchanged in a reaction may have on the catalyst. Here we obtain single-molecule fluorescence correlation spectroscopy data and analyse them within the framework of a stochastic theorymore » to demonstrate a mechanistic link between the enhanced diffusion of a single enzyme molecule and the heat released in the reaction. We propose that the heat released during catalysis generates an asymmetric pressure wave that results in a differential stress at the protein-solvent interface that transiently displaces the centre-of-mass of the enzyme (chemoacoustic effect). We find this novel perspective on how enzymes respond to the energy released during catalysis suggests a possible effect of the heat of reaction on the structural integrity and internal degrees of freedom of the enzyme.« less

  6. The heat released during catalytic turnover enhances the diffusion of an enzyme

    SciTech Connect

    Riedel, Clement; Gabizon, Ronen; Wilson, Christian A. M.; Hamadani, Kambiz; Tsekouras, Konstantinos; Marqusee, Susan; Pressé, Steve; Bustamante, Carlos

    2014-12-10

    Recent studies have shown that the diffusivity of enzymes increases in a substrate-dependent manner during catalysis. Although this observation has been reported and characterized for several different systems, the precise origin of this phenomenon is unknown. Calorimetric methods are often used to determine enthalpies from enzyme-catalysed reactions and can therefore provide important insight into their reaction mechanisms. The ensemble averages involved in traditional bulk calorimetry cannot probe the transient effects that the energy exchanged in a reaction may have on the catalyst. Here we obtain single-molecule fluorescence correlation spectroscopy data and analyse them within the framework of a stochastic theory to demonstrate a mechanistic link between the enhanced diffusion of a single enzyme molecule and the heat released in the reaction. We propose that the heat released during catalysis generates an asymmetric pressure wave that results in a differential stress at the protein-solvent interface that transiently displaces the centre-of-mass of the enzyme (chemoacoustic effect). We find this novel perspective on how enzymes respond to the energy released during catalysis suggests a possible effect of the heat of reaction on the structural integrity and internal degrees of freedom of the enzyme.

  7. 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.

  8. Heat-Induced Release of Epigenetic Silencing Reveals the Concealed Role of an Imprinted Plant Gene

    PubMed Central

    Sanchez, Diego H.; Paszkowski, Jerzy

    2014-01-01

    Epigenetic mechanisms suppress the transcription of transposons and DNA repeats; however, this suppression can be transiently released under prolonged heat stress. Here we show that the Arabidopsis thaliana imprinted gene SDC, which is silent during vegetative growth due to DNA methylation, is activated by heat and contributes to recovery from stress. SDC activation seems to involve epigenetic mechanisms but not canonical heat-shock perception and signaling. The heat-mediated transcriptional induction of SDC occurs particularly in young developing leaves and is proportional to the level of stress. However, this occurs only above a certain window of absolute temperatures and, thus, resembles a thermal-sensing mechanism. In addition, the re-silencing kinetics during recovery can be entrained by repeated heat stress cycles, suggesting that epigenetic regulation in plants may conserve memory of stress experience. We further demonstrate that SDC contributes to the recovery of plant biomass after stress. We propose that transcriptional gene silencing, known to be involved in gene imprinting, is also co-opted in the specific tuning of SDC expression upon heat stress and subsequent recovery. It is therefore possible that dynamic properties of the epigenetic landscape associated with silenced or imprinted genes may contribute to regulation of their expression in response to environmental challenges. PMID:25411840

  9. Gas dynamics of heat-release-induced waves in supercritical fluids: revisiting the Piston Effect

    NASA Astrophysics Data System (ADS)

    Migliorino, Mario Tindaro; Scalo, Carlo

    2016-11-01

    We investigate a gasdynamic approach to the modeling of heat-release-induced compression waves in supercritical fluids. We rely on highly resolved one-dimensional fully compressible Navier-Stokes simulations of CO2 at pseudo-boiling conditions in a closed duct inspired by the experiments of Miura et al.. Near-critical fluids exhibit anomalous variations of thermodynamic variables taken into account by adopting the Peng-Robinson equation of state and Chung's Method. An idealized heat source is applied, away from the boundaries, resulting in the generation of compression waves followed by contact discontinuities bounding a region of hot expanding fluid. For higher heat-release rates such compressions are coalescent with distinct shock-like features (i.e. non-isentropicity and propagation Mach numbers measurably greater than unity) and a non-uniform post-shock state, not present in ideal gas simulations, caused by the highly nonlinear equation of state. Thermoacoustic effects are limited to: (1) a one-way/one-time thermal-to-acoustic energy conversion, and (2) cumulative non-isentropic bulk heating due to the resonating compression waves, resulting in what is commonly referred to as the Piston Effect.

  10. Liquid-Phase Heat-Release Rates of the Systems Hydrazine-Nitric Acid and Unsymmetrical Dimethylhydrazine-Nitric Acid

    NASA Technical Reports Server (NTRS)

    Somogyi, Dezso; Feiler, Charles E.

    1960-01-01

    The initial rates of heat release produced by the reactions of hydrazine and unsymmetrical dimethylhydrazine with nitric acid were determined in a bomb calorimeter under conditions of forced mixing. Fuel-oxidant weight ratio and injection velocity were varied. The rate of heat release apparently depended on the interfacial area between the propellants. Above a narrow range of injection velocities representing a critical amount of interfacial area, the rates reached a maximum and were almost constant with injection velocity. The maximum rate for hydrazine was about 70 percent greater than that for unsymmetrical dimethylhydrazine. The total heat released did not vary with mixture ratio over the range studied.

  11. Inflammatory stress of pancreatic beta cells drives release of extracellular heat shock protein 90α.

    PubMed

    Ocaña, Gail J; Pérez, Liliana; Guindon, Lynette; Deffit, Sarah N; Evans-Molina, Carmella; Thurmond, Debbie C; Blum, Janice S

    2017-02-11

    A major obstacle in predicting and preventing the development of autoimmune type 1 diabetes (T1D) in at-risk individuals is the lack of well-established early biomarkers indicative of ongoing beta cell stress during the pre-clinical phase of disease. Recently, serum levels of the alpha cytoplasmic isoform of heat shock protein (HSP) 90 were shown to be elevated in individuals with new-onset T1D. We therefore hypothesized HSP90α could be released from beta cells in response to cellular stress and inflammation associated with the earliest stages of T1D. Here, human beta cell lines and cadaveric islets released HSP90α in response to stress induced by treatment with a combination of pro-inflammatory cytokines including IL-1β, TNF-α, and IFN-γ. Mechanistically, HSP90α release was found to be driven by cytokine-induced endoplasmic reticulum (ER) stress mediated by c-Jun N-terminal kinase (JNK), a pathway that can eventually lead to beta cell apoptosis. Cytokine-induced beta cell HSP90α release and JNK activation were significantly reduced by pre-treating cells with the ER stress-mitigating chemical chaperone tauroursodeoxycholic acid (TUDCA). HSP90α release by cells may thus be a sensitive indicator of stress during inflammation and a useful tool in assessing therapeutic mitigation of cytokine-induced cell damage linked to autoimmunity. This article is protected by copyright. All rights reserved.

  12. Near-Infrared-Induced Heating of Confined Water in Polymeric Particles for Efficient Payload Release

    PubMed Central

    2015-01-01

    Near-infrared (NIR) light-triggered release from polymeric capsules could make a major impact on biological research by enabling remote and spatiotemporal control over the release of encapsulated cargo. The few existing mechanisms for NIR-triggered release have not been widely applied because they require custom synthesis of designer polymers, high-powered lasers to drive inefficient two-photon processes, and/or coencapsulation of bulky inorganic particles. In search of a simpler mechanism, we found that exposure to laser light resonant with the vibrational absorption of water (980 nm) in the NIR region can induce release of payloads encapsulated in particles made from inherently non-photo-responsive polymers. We hypothesize that confined water pockets present in hydrated polymer particles absorb electromagnetic energy and transfer it to the polymer matrix, inducing a thermal phase change. In this study, we show that this simple and highly universal strategy enables instantaneous and controlled release of payloads in aqueous environments as well as in living cells using both pulsed and continuous wavelength lasers without significant heating of the surrounding aqueous solution. PMID:24717072

  13. Acetylcholine released from cholinergic nerves contributes to cutaneous vasodilation during heat stress

    NASA Technical Reports Server (NTRS)

    Shibasaki, Manabu; Wilson, Thad E.; Cui, Jian; Crandall, Craig G.

    2002-01-01

    Nitric oxide (NO) contributes to active cutaneous vasodilation during a heat stress in humans. Given that acetylcholine is released from cholinergic nerves during whole body heating, coupled with evidence that acetylcholine causes vasodilation via NO mechanisms, it is possible that release of acetylcholine in the dermal space contributes to cutaneous vasodilation during a heat stress. To test this hypothesis, in seven subjects skin blood flow (SkBF) and sweat rate were simultaneously monitored over three microdialysis membranes placed in the dermal space of dorsal forearm skin. One membrane was perfused with the acetylcholinesterase inhibitor neostigmine (10 microM), the second membrane was perfused with the NO synthase inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME; 10 mM) dissolved in the aforementioned neostigmine solution (l-NAME(Neo)), and the third membrane was perfused with Ringer solution as a control site. Each subject was exposed to approximately 20 min of whole body heating via a water-perfused suit, which increased mean body temperature from 36.4 +/- 0.1 to 37.5 +/- 0.1 degrees C (P < 0.05). After the heat stress, SkBF at each site was normalized to its maximum value, identified by administration of 28 mM sodium nitroprusside. Mean body temperature threshold for cutaneous vasodilation was significantly lower at the neostigmine-treated site relative to the other sites (neostigmine: 36.6 +/- 0.1 degrees C, l-NAME(Neo): 37.1 +/- 0.1 degrees C, control: 36.9 +/- 0.1 degrees C), whereas no significant threshold difference was observed between the l-NAME(Neo)-treated and control sites. At the end of the heat stress, SkBF was not different between the neostigmine-treated and control sites, whereas SkBF at the l-NAME(Neo)-treated site was significantly lower than the other sites. These results suggest that acetylcholine released from cholinergic nerves is capable of modulating cutaneous vasodilation via NO synthase mechanisms early in the heat stress but

  14. Sensitivity of hydrometeor profiles and satellite brightness temperatures to model microphysics for MCSs over land and ocean: Model comparison using EOF analysis and implications for rain and latent heat retrievals

    NASA Astrophysics Data System (ADS)

    Seo, Eun-Kyoung

    The impact of model microphysics on the relationships between microphysical variables and derived satellite microwave brightness temperatures (T B's) and on the retrievals of microphysical variables was using a three-dimensional, nonhydrostatic, adaptive-grid cloud model to simulate two mesoscale convective systems, one over land and one over ocean. Four microphysical schemes (each employing 3-ice bulk parameterizations) were compared in both convective and stratiform precipitation using Empirical Orthogonal Function analysis. The validity of the microphysical schemes suggests that over land the model microphysical schemes produce too much reflectivity aloft and too rapid a decrease in reflectivity from the melting level to the surface, and over ocean the simulations produced more graupel and not enough rain. Model microphysics had a noticeable impact on the relations between the hydrometeor structure and TB's. Classified in terms of TB 's, the microphysical schemes produce significantly different mean vertical profiles of cloud water, cloud ice, snow, vertical velocity, and latent heating, especially in stratiform clouds. Vertical velocity and latent heating in simulated stratiform clouds were not well correlated with TB's for any of the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) frequencies. Differences in the amount of supercooled cloud water produced in the various schemes accounted for much of the variation in TB relations. The uncertainty in retrieving hydrometeor and latent heating profiles for passive microwave measurements has been examined quantitatively. The four microphysical schemes exhibited analogous uncertainties in retrieving rain and graupel, but very different uncertainties in retrieving cloud water, cloud ice, and snow. The uncertainty in retrieving latent heating appears to be related to the insensitivity of TMI frequencies to cloud water, cloud ice, and snow. Structural differences in hydrometeor and latent heating

  15. Thermal energy storage – overview and specific insight into nitrate salts for sensible and latent heat storage

    PubMed Central

    Bauer, Thomas; Martin, Claudia; Eck, Markus; Wörner, Antje

    2015-01-01

    Summary Thermal energy storage (TES) is capable to reduce the demand of conventional energy sources for two reasons: First, they prevent the mismatch between the energy supply and the power demand when generating electricity from renewable energy sources. Second, utilization of waste heat in industrial processes by thermal energy storage reduces the final energy consumption. This review focuses mainly on material aspects of alkali nitrate salts. They include thermal properties, thermal decomposition processes as well as a new method to develop optimized salt systems. PMID:26199853

  16. Multiple solutions and numerical analysis to the dynamic and stationary models coupling a delayed energy balance model involving latent heat and discontinuous albedo with a deep ocean.

    PubMed

    Díaz, J I; Hidalgo, A; Tello, L

    2014-10-08

    We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge-Kutta total variation diminishing for time integration.

  17. Multiple solutions and numerical analysis to the dynamic and stationary models coupling a delayed energy balance model involving latent heat and discontinuous albedo with a deep ocean

    PubMed Central

    Díaz, J. I.; Hidalgo, A.; Tello, L.

    2014-01-01

    We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge–Kutta total variation diminishing for time integration. PMID:25294969

  18. Quantification and attribution of errors in the simulated annual gross primary production and latent heat fluxes by two global land surface models

    NASA Astrophysics Data System (ADS)

    Li, Jianduo; Wang, Ying-Ping; Duan, Qingyun; Lu, Xingjie; Pak, Bernard; Wiltshire, Andy; Robertson, Eddy; Ziehn, Tilo

    2016-09-01

    Differences in the predicted carbon and water fluxes by different global land models have been quite large and have not decreased over the last two decades. Quantification and attribution of the uncertainties of global land surface models are important for improving the performance of global land surface models, and are the foci of this study. Here we quantified the model errors by comparing the simulated monthly global gross primary productivity (GPP) and latent heat flux (LE) by two global land surface models with the model-data products of global GPP and LE from 1982 to 2005. By analyzing model parameter sensitivities within their ranges, we identified about 2-11 most sensitive model parameters that have strong influences on the simulated GPP or LE by two global land models, and found that the sensitivities of the same parameters are different among the plant functional types (PFT). Using parameter ensemble simulations, we found that 15%-60% of the model errors were reduced by tuning only a few (<4) most sensitive parameters for most PFTs, and that the reduction in model errors varied spatially within a PFT or among different PFTs. Our study shows that future model improvement should optimize key model parameters, particularly those parameters relating to leaf area index, maximum carboxylation rate, and stomatal conductance.

  19. Heat-Driven Release of a Drug Molecule From Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Chaban, Vitaly; Prezhdo, Oleg

    2011-03-01

    Hydrophobicity and ability to absorb light that penetrates through living tissues make carbon nanotubes (CNTs) promising intracellular drug delivery agents. Following insertion of a drug molecule into a CNT, the latter is delivered into a tissue, is heated by near infrared radiation, and releases the drug. In order to assess the feasibility of this scheme, we investigate the rates of energy transfer between CNT, water and the drug molecule, and study the temperature and concentration dependence of the diffusion coefficient of the drug molecule inside CNTs. We use ciprofloxacin (CIP) as a sample drug: direct penetration of CIP through cell membranes is problematic due to its high polarity. The simulations show that a heated CNT rapidly deposits its energy to CIP and water. All estimated timescales for the vibrational energy exchange between CNT, CIP and water are less than 10 ps at 298 K. As the system temperature grows from 278 K to 363 K, the diffusion coefficient of the confined CIP increases 5-7 times, depending on CIP concentration. The diffusion coefficient slightly drops with increasing CIP concentration. This effect is more pronounced at higher temperatures. The simulations support the idea that optical heating of CNTs can assist in releasing encapsulated drugs.

  20. Factors Affecting Release of Heat-Labile Enterotoxin by Enterotoxigenic Escherichia coli

    PubMed Central

    Kunkel, Steven L.; Robertson, Donald C.

    1979-01-01

    Various conditions affecting the release of heat-labile enterotoxin (LT) by enterotoxigenic Escherichia coli have been examined. The pH of a defined medium containing three amino acids, M-9 salts, and 0.5% glucose decreased to less than 7.0 in early log phase of growth, and no extracellular LT was detected. Adjustment of the pH at 8 h from 6.0 to 8.0 resulted in a concomitant increase in LT activity in culture supernatants. The release of cell-associated LT was significantly reduced by preincubation with protease inhibitors and increased by preincubation with trypsin. Cell-associated LT was not released by pH adjustment of cells grown at 21°C; however, polymyxin B treatment released a toxin species active in only the pigeon erythrocyte lysate (PEL) assay system. As the growth temperature was increased, polymyxin B released toxin species which exhibited both PEL and Y-1 adrenal tumor cell activity. Polymyxin B extracts of enterotoxigenic E. coli in early log phase grown at 37°C possessed only PEL activity, whereas extracts from cells in late-log and stationary phases had biological activity in both assay systems. Also, LT released by pH adjustment from mid-log to stationary phase was active in both PEL and Y-1 adrenal tumor cell assays. Gel electrophoresis of polymyxin B extracts revealed at least three molecular weight species active in either the PEL (22,000 daltons and 30,000 daltons) or both the PEL and the Y-1 adrenal tumor cell assay (72,000 daltons), depending on the growth temperature. These observations may help to explain the chemical and biological heterogeneity of most LT preparations and facilitate purification of LT by increasing the yield of enterotoxin. PMID:37162

  1. Combustion Gases And Heat Release Analysis During Flame And Flameless Combustion Of Wood Pellets

    NASA Astrophysics Data System (ADS)

    Horváth, Jozef; Wachter, Igor; Balog, Karol

    2015-06-01

    With the growing prices of fossil fuels, alternative fuels produced of biomass come to the fore. They are made of waste materials derived from the processing of wood and wood materials. The main objective of this study was to analyse the fire-technical characteristics of wood pellets. The study analysed three dust samples acquired from wood pellets made of various types of wood biomass. Wood pellet dust is produced when manipulating with pellets. During this process a potentially hazardous situations may occur. Biomass is chemically composed mostly of hemicellulose, cellulose and lignin. During straining of the biomass by heat flux, combustion initiation occurs. Also, there was a change in the composition of material throughout combustion gases production, and the amount of heat generated by a flame or flameless combustion. Measurement of fire characteristics was conducted according to ISO 5660-1 standard using a cone calorimeter. Two samples of wood pellet dust were tested under the heat flux of 35 kW.m-2 and 50 kW.m-2. The process of combustion, the time to ignition, the carbon monoxide concentration and the amount of released heat were observed.

  2. Solar heat storage in phase change material

    SciTech Connect

    Phillips, H.J.

    1984-02-28

    The objective of this project was to develop a chemical heat storage system that had a phase change with release of latent heat at about 105/sup 0/F. The primary reason this kind on system was sought was that heat storage capacity of commonly used storage systems do not match the heat collection capacity of open air collectors. In addition to the phase change three other factors were considered: the cost of the material, the amount of heat the system would hold per unit volume, and the rate at which the system released sensible and latent heat. One hundred nineteen tests were made on 32 systems. Only data on six of the more promising are presented. In the six systems, borax was used as the major component with other materials used as nucleating agents toraise the temperature of phase change.

  3. Measurements of the heat release rate integral in turbulent premixed stagnation flames with particle image velocimetry

    SciTech Connect

    Chen, Yung-Cheng; Kim, Munki; Han, Jeongjae; Yun, Sangwook; Yoon, Youngbin

    2008-08-15

    A new definition of turbulent consumption speed is proposed in this work that is based on the heat release rate integral, rather than the mass burning rate integral. Its detailed derivation and the assumptions involved are discussed in a general context that applies to all properly defined reaction progress variables. The major advantage of the proposed definition is that it does not require the thin-flame assumption, in contrast to previous definitions. Experimental determination of the local turbulent displacement speed, S{sub D}, and the local turbulent consumption speed, S{sub C}, is also demonstrated with the particle image velocimetry technique in three turbulent premixed stagnation flames. The turbulence intensity of these flames is of the same order of the laminar burning velocity. Based on the current data, a model equation for the local mean heat release rate is proposed. The relationship between S{sub D} and S{sub C} is discussed along with a possible modeling approach for the turbulent displacement speed. (author)

  4. Planar laser-induced fluorescence imaging of flame heat release rate

    SciTech Connect

    Paul, P.H.; Najm, H.N.

    1997-12-12

    Local heat release rate represents one of the most interesting experimental observables in the study of unsteady reacting flows. The direct measure of burning or heat release rate as a field variable is not possible. Numerous experimental investigations have relied on inferring this type of information as well as flame front topology from indirect measures which are presumed to be correlated. A recent study has brought into question many of the commonly used flame front marker and burning rate diagnostics. This same study found that the concentration of formyl radical offers the best possibility for measuring flame burning rate. However, primarily due to low concentrations, the fluorescence signal level from formyl is too weak to employ this diagnostic for single-pulse measurements of turbulent reacting flows. In this paper the authors describe and demonstrate a new fluorescence-based reaction front imaging diagnostic suitable for single-shot applications. The measurement is based on taking the pixel-by-pixel product of OH and CH{sub 2}O planar laser-induced fluorescence images to yield an image closely related to a reaction rate. The spectroscopic and collisional processes affecting the measured signals are discussed and the foundation of the diagnostic, as based on laminar and unsteady flame calculations, is presented. The authors report the results of applying this diagnostic to the study of a laminar premixed flame subject to an interaction with an isolated line-vortex pair.

  5. δ-FeOOH: a superparamagnetic material for controlled heat release under AC magnetic field

    NASA Astrophysics Data System (ADS)

    Chagas, Poliane; da Silva, Adilson Cândido; Passamani, Edson Caetano; Ardisson, José Domingos; de Oliveira, Luiz Carlos Alves; Fabris, José Domingos; Paniago, Roberto M.; Monteiro, Douglas Santos; Pereira, Márcio César

    2013-04-01

    Experimental evidences on its in vitro use reveal that δ-FeOOH is a material that release-controlled amount of heat if placed under an AC magnetic field. δ-FeOOH nanoparticles were prepared by precipitating Fe(OH)2 in alkaline solution followed by fast oxidation with H2O2. XRD and 57Fe Mössbauer spectroscopy data confirmed that δ-FeOOH is indeed the only iron-bearing compound in the produced sample. TEM images evidence that the averaged particle sizes for this δ-FeOOH sample is 23 nm. Magnetization measurements indicate that these δ-FeOOH particles behave superparamagnetically at 300 K; its saturation magnetization was found to be 13.2 emu g-1; the coercivity and the remnant magnetization were zero at 300 K. The specific absorption rate values at 225 kHz were 2.1, 6.2, and 34.2 W g-1, under 38, 64, and 112 mT, respectively. The release rate of heat can be directly controlled by changing the mass of δ-FeOOH nanoparticles. In view of these findings, the so-prepared δ-FeOOH is a real alternative to be further tested as a material for medical practices in therapies involving magnetic hyperthermia as in clinical oncology.

  6. Comparison of the spatial and temporal distribution of fluxes of sensible heat, latent heat and CO2 from grid flights in BOREAS 1994 and 1996

    NASA Astrophysics Data System (ADS)

    Ogunjemiyo, Segun O.; Schuepp, Peter H.; MacPherson, Ian J.; Desjardins, Ray L.

    1999-11-01

    Analysis of airborne eddy correlation flux measurements of heat (H), moisture (LE) and CO2 (C) over two 16 km × 16 km heterogeneous grid sites in BOREAS 1994 (IFC-2) and 1996 are compared in order to examine persistence and variability in the distributions of surface characteristics and fluxes between the two years. The data used were obtained in grid patterns flown at 30 m above ground level, under generally clear sky and thermally unstable conditions. Maps of fluxes and surface characteristics were constructed by block averaging over 2 km windows along the flight lines, analyzed for similarities, and used to quantify spatial variability of the fluxes. Sensitivity analysis suggested minor effects of boundary layer variability and window size on the main features of the source/sink distributions. Incident radiation was more highly correlated with grid-averaged values of C than with H and LE. The dominant role of surface inhomogeneity, as opposed to local variations in solar energy input, on spatial variation of flux distributions was confirmed, and mesoscale motion was found negligible, probably because of the small sizes of homogeneous subareas with sufficient surface contrast to induce thermally generated motion. CO2 flux and greenness index were highly correlated, but correlation was site- and time-specific. The previously observed low correlation between sensible heat flux and surface minus air temperature difference (Ts-Ta), primarily over old black spruce, was confirmed. The high Bowen ratio over the forest contributed to the growth and development of the observed deep boundary layers over the sites, but no clear correlation emerged between boundary layer depth and observed near-surface fluxes.

  7. Measuring the Heats of Water.

    ERIC Educational Resources Information Center

    Hunt, James L.; Tegart, Tracy L.

    1994-01-01

    Uses common equipment (tea kettle and vacuum bottles) to precisely measure the specific heat, latent heat of fusion, and latent heat of vaporization of water. Provides descriptions for all three experiments. (MVL)

  8. Heat-Induced Reactivation of HSV-1 in Latent Mice: Upregulation in the TG of CD83 and Other Immune Response Genes and Their LAT-ICP0 Locus

    PubMed Central

    Clement, Christian; Bhattacharjee, Partha S.; Kaufman, Herbert E.; Hill, James M.

    2009-01-01

    Purpose To determine changes in host gene expression in HSV-1 latent trigeminal ganglia (TG) after hyperthermic stress. Methods Scarified corneas of 6-week-old female BALB/c mice were inoculated with either HSV-1 17Syn+ (high phenotypic reactivator) or 17ΔPst(LAT−) (low phenotypic reactivator) at 104 plaque-forming units/eye. At 28 days after infection, viral reactivation was induced in some of the infected mice with hyperthermic stress, and the mice were killed after 1 hour. Heat-treated uninfected mice served as the control. Labeled cRNA derived from TG-isolated total RNA was hybridized to 430 2.0 chips containing 14,000 mouse genes. Gene expression was confirmed by quantitative real-time PCR. Results There was no difference in gene expression in the non–heat-treated mice. Gene expression in the TG of each of the heat-treated mouse groups (17Syn+, 17ΔPst(LAT−) and uninfected) yielded upregulation of more than twofold of a group of the same genes, designated as heat stress–induced gene expression. Twenty-nine genes (0.2%) were significantly upregulated (2- to 17-fold) when the heat stress–induced gene expression was subtracted from the gene expression of 17Syn+ latent TG relative to 17ΔPst(LAT−) latent TG 1 hour after mouse hyperthermic stress. Nine host adaptive immunity genes comprising Ig molecules, CD83, CD8A, ADA, and CCL8 were the largest subset upregulated, and all were confirmed by real-time PCR. Others identified included genes involved in hypothalamic-pituitary gland functions. Conclusions Hyperthermic stress–induced reactivation of the HSV-1 high phenotypic reactivator can upregulate gene expression involved in B-cell function and in T-cell function. CD83 is implicated in HSV-1 latency, suggesting it could also be involved in immune-mediated mechanisms of viral reactivation. PMID:19151393

  9. Release of H and He from TiC, stainless steel and graphite by pulsed electron and furnace heating

    SciTech Connect

    Picraux, S.T.; Wampler, W.R.

    1980-01-01

    The release of implanted D and /sup 3/He from TiC coatings, SS 304 and graphite by pulsed electron beam (e-beam) heating and furnace heating has been investigated. Low fluence implants of D or /sup 3/He and saturation fluence D implants have been studied for 0.5 - 1.5 keV D and 3 keV /sup 3/He. The retained D or /sup 3/He was monitored by ion beam analysis. The 50 ns e-beam pulsing resulted in the release of D in all materials and was compared with release during isochronal annealing in a furnace. A substantial enhancement in the fractional D release was found for D saturated TiC (0.25 D to host atom ratio) compared with low fluence implants. In contrast no enhancement of D release was observed for D saturated graphite and SS 304 compared with low fluence implants. Release of /sup 3/He from TiC was also obtained by e-beam pulsed heating and this release was not affected by the presence of saturation concentrations of D. Comparison to furnace anneals and the calculated time evolution of the temperature profiles suggests a simple model for the D release based on diffusion-limited release in the case of pulsed e-beam treatments and trap-limited release in the case of furnace bulk heating. These processes are closely related to hydrogen recycle in tokamaks and have implications for T inventory control and He ash removal.

  10. Wet-season Dormancy Release in Seed Banks of a Tropical Leguminous Shrub is Determined by Wet Heat

    PubMed Central

    VAN KLINKEN, RIEKS D.; FLACK, LLOYD K.; PETTIT, WILLIAM

    2006-01-01

    • Background and Aims Hard-seeded (physical) dormancy is common among plants, yet mechanisms for dormancy release are poorly understood, especially in the tropics. The following questions are asked: (a) whether dormancy release in seed banks of the tropical shrub Parkinsonia aculeata (Caesalpiniaceae) is determined by wet heat (incubation under wet, warm to hot, conditions); and (b) whether its effect is modified by microclimate. • Methods A seed burial trial was conducted in the wet–dry tropics (northern Australia) to compare dormancy release across different habitats (open, artificial cover, ground cover and canopy cover), burial depths (0, 3 and 20 cm) and burial durations (2, 6 and 14 weeks). Results were compared with predictions using a laboratory-derived relationship between wet heat and dormancy release, and microclimate data collected during the trial. • Key Results Wet heat (defined as the soil temperature above which seeds were exposed to field capacity or higher for a cumulative total of 24 h) was 43·6 °C in the 0 cm open treatment, and decreased with increasing shade and depth to 29·5 °C at 20 cm under canopy cover. The dormancy release model showed that wet heat was a good predictor of the proportion of seeds remaining dormant. Furthermore, dormancy release was particularly sensitive to wet heat across the temperature range encountered across treatments. This resulted in a 16-fold difference in dormancy levels between open (<5 % of seeds still dormant) and covered (82 %) microhabitats. • Conclusions These results demonstrate that wet heat is the principal dormancy release mechanism for P. aculeata when conditions are hot and wet. They also highlight the potential importance of microclimate in driving the population dynamics of such species. PMID:16891334

  11. Towards Measurement of the Time-resolved Heat Release of Protein Conformation Dynamics

    NASA Technical Reports Server (NTRS)

    Puchalla, Jason; Adamek, Daniel; Austin, Robert

    2004-01-01

    We present a way to observe time-resolved heat release using a laminar flow diffusional mixer coupled with a highly sensitive infrared camera which measures the temperature change of the solvent. There are significant benefits to the use of laminar flow mixers for time-resolved calorimetry: (1) The thermal signal can be made position and time- stationary to allow for signal integration; (2) Extremely small volumes (nl/s) of sample are required for a measurement; (3) The same mixing environment can be observed spectroscopically to obtain state occupation information; (4) The mixer allows one to do out of equilibrium dynamic studies. The hope is that these measurements will allow us probe the non-equilibrium thermodynamics as a protein moves along a free energy trajectory from one state to another.

  12. Characterization of nonlinear heat release-acoustic interactions in gas turbine combustors

    NASA Astrophysics Data System (ADS)

    Bellows, Benjamin D.

    This thesis describes an experimental investigation of the flame transfer function between flow disturbances and heat release oscillations in lean, premixed combustors. This research effort was motivated by the fact that modern gas turbines, operating fuel lean to minimize exhaust emissions, are susceptible to self-excited combustion oscillations. These instabilities generally occur when the unsteady combustion process couples with the acoustic modes of the combustion chamber. The resultant flow and structural vibrations can substantially reduce hot section part life. As such, avoiding operating regimes where high dynamics occur often requires operating at lower power outputs and/or higher pollutant emissions than the turbine is otherwise capable. This work demonstrated nonlinearities in the chemiluminescence response at large amplitude velocity oscillations in a turbulent, swirling flame. It is observed that the nonlinear flame response can exhibit a variety of behaviors, both in the shape of the response curve and the forcing amplitude at which nonlinearity is first observed depending on the operating conditions of the combustor. The phase between the flow oscillations and heat release is also seen to have substantial amplitude dependence. In addition, the interactions between the fundamental frequency and the higher and subharmonics of the measured signals can significantly influence the flame as well as the frequency response of the system. The nonlinear flame dynamics are governed by different mechanisms in different frequency and flowrate regimes. Three mechanisms, vortex rollup, unsteady flame liftoff, and parametric instability, are identified to influence the nonlinear flame response in these combustors. Analysis of the results shows that the mechanisms responsible for nonlinearity m the flame response are influenced by the Strouhal number, the mean velocity at the combustor dump plane, and the ratio of the oscillating velocity amplitude to the laminar

  13. Extracellular Release and Signaling by Heat Shock Protein 27: Role in Modifying Vascular Inflammation

    PubMed Central

    Batulan, Zarah; Pulakazhi Venu, Vivek Krishna; Li, Yumei; Koumbadinga, Geremy; Alvarez-Olmedo, Daiana Gisela; Shi, Chunhua; O’Brien, Edward R.

    2016-01-01

    Heat shock protein 27 (HSP27) is traditionally viewed as an intracellular chaperone protein with anti-apoptotic properties. However, recent data indicate that a number of heat shock proteins, including HSP27, are also found in the extracellular space where they may signal via membrane receptors to alter gene transcription and cellular function. Therefore, there is increasing interest in better understanding how HSP27 is released from cells, its levels and composition in the extracellular space, and the cognate cell membrane receptors involved in effecting cell signaling. In this paper, the knowledge to date, as well as some emerging paradigms about the extracellular function of HSP27 is presented. Of particular interest is the role of HSP27 in attenuating atherogenesis by modifying lipid uptake and inflammation in the plaque. Moreover, the abundance of HSP27 in serum is an emerging new biomarker for ischemic events. Finally, HSP27 replacement therapy may represent a novel therapeutic opportunity for chronic inflammatory disorders, such as atherosclerosis. PMID:27507972

  14. Selective release from cultured mammalian cells of heat-shock (stress) proteins that resemble glia-axon transfer proteins.

    PubMed

    Hightower, L E; Guidon, P T

    1989-02-01

    Cultured rat embryo cells were stimulated to rapidly release a small group of proteins that included several heat-shock proteins (hsp110, hsp71, hscp73) and nonmuscle actin. The extracellular proteins were analyzed by two-dimensional polyacrylamide gel electrophoresis. Heat-shocked cells released the same set of proteins as control cells with the addition of the stress-inducible hsp110 and hsp71. Release of these proteins was not blocked by either monensin or colchicine, inhibitors of the common secretory pathway. A small amount of the glucose-regulated protein grp78 was externalized by this pathway. The extracellular accumulation of these proteins was inhibited after they were synthesized in the presence of the lysine analogue aminoethyl cysteine. It is likely that the analogue-substituted proteins were misfolded and could not be released from cells, supporting our conclusion that a selective release mechanism is involved. Remarkably, actin and the squid heat-shock proteins homologous to rat hsp71 and hsp110 are also among a select group of proteins transferred from glial cells to the squid giant axon, where they have been implicated in neuronal stress responses (Tytell et al.: Brain Res., 363:161-164, 1986). Based in part on the similarities between these two sets of proteins, we hypothesized that these proteins were released from labile cortical regions of animal cells in response to perturbations of homeostasis in cells as evolutionarily distinct as cultured rat embryo cells and squid glial cells.

  15. Effect of dry heating and ionic gum on the physicochemical and release properties of starch from Dioscorea.

    PubMed

    Vashisht, Deepika; Pandey, Anima; Hermenean, Anca; Yáñez-Gascón, Maria Josefa; Pérez-Sánchez, Horacio; Kumar, K Jayaram

    2017-02-01

    To meet the ever increasing industrial demand for excipients with desirable properties, modified starch is regarded as an alternative to it. With this in mind, the present study focuses on the modification of starches of Dioscorea from Jharkhand (India) using dry heat treatment with and without ionic gum. Modified starches were prepared using sodium alginate (1% w/w). Native and modified starches were subjected to heat treatment at 130°C for 2h and 4h. The effect of heating and ionic gum on the properties of Dioscorea starch was investigated. The amylose content, water holding capacity, micromeritic properties, swelling power, solubility and morphology of starches were evaluated. Dry heat treatment of starches without gum showed an increment in water-holding capacity after two-hours heating, but no such increment was found after four-hours heating. Oil binding capacity of starches modified with gum varied from 62% to 78%. Strongest effect of heat treatment occurred on the morphology of starches and thereby modified starches showed distorted surface morphology. Amylose content (21.09-21.89%) found to be decreased with the addition of gum which lead to decrease in paste clarity. Starches heated with gum at high-temperature resulted in restrict swelling and slight increase in solubility. Micromeritic properties of the modified starches showed the good flow properties. Further, the modified starches were investigated for in-vitro release studies and that the thermally modified derivatives can be a good prospect in slow release formulations.

  16. Low effective activation energies for oxygen release from metal oxides: evidence for mass-transfer limits at high heating rates.

    PubMed

    Jian, Guoqiang; Zhou, Lei; Piekiel, Nicholas W; Zachariah, Michael R

    2014-06-06

    Oxygen release from metal oxides at high temperatures is relevant to many thermally activated chemical processes, including chemical-looping combustion, solar thermochemical cycles and energetic thermite reactions. In this study, we evaluated the thermal decomposition of nanosized metal oxides under rapid heating (~10(5) K s(-1)) with time-resolved mass spectrometry. We found that the effective activation-energy values that were obtained using the Flynn-Wall-Ozawa isoconversional method are much lower than the values found at low heating rates, indicating that oxygen transport might be rate-determining at a high heating rate.

  17. Jet streak modification via diabatic heating during periods of intense cool-season precipitation

    NASA Astrophysics Data System (ADS)

    Market, Patrick Shawn

    The propagation of a jet streak in the presence of predominately stable latent heat release is examined. Unlike many prior studies which emphasized latent heat release due to mesoscale convective system activity this work addresses cool season mid-latitude weather systems in which stable latent heat release played a significant role. In both cool and warm seasons, the result is the same: the amplification of a pre-existing jet streak, or the in situ development of a new jet streak. The former situation is more typical of the cool season when thermal gradients and the jet stream are both stronger and more conducive to the transient baroclinic waves which engender streaks in the jet stream flow, while the latter development tends to be the product of a warm season environment when the background thermal and flow patterns are weaker. In this work, the development of a pre-existing straight- line jet streak upstream of its prior location (``backbuilding'') presumably due to latent heat release is studied. Both dry and moist adiabatic simulations with a mesoscale numerical model indicate that backbuilding occurs in the absence of latent heat release (dry run) due to confluence but is enhanced when such heating is included (moist run). This is due to the latent heat release and consequent warming of the column in which it occurs, thus altering the height gradient. Such a process causes accelerations in the flow. Moreover, the mid-tropospheric nature of the stable latent heating causes the backbuilding to be maximized in the mid-troposphere (500 to 400 hPa). Isentropic coordinate analyses of the model output are employed in the estimation of latent heating and ageostrophic wind components. In terms of sensible weather, the propagating jet streak tends to initiate precipitation in its right entrance region because of the induced ascent. In the present case, the latent heat release associated with this precipitation acted to anchor the jet streak in place and even build

  18. Recent advances in testing for latent TB.

    PubMed

    Schluger, Neil W; Burzynski, Joseph

    2010-12-01

    After more than a century of relying on skin testing for the diagnosis of latent TB infection, clinicians now have access to blood-based diagnostics in the form of interferon γ release assays (IGRAs). These tests are generally associated with higher sensitivity and specificity for diagnosis of latent TB infection. This article reviews the indications for testing and treatment of latent TB infection in the overall context of a TB control program and describes how IGRAs might be used in specific clinical settings and populations, including people having close contact with an active case of TB, the foreign born, and health-care workers.

  19. Generalized Latent Trait Models.

    ERIC Educational Resources Information Center

    Moustaki, Irini; Knott, Martin

    2000-01-01

    Discusses a general model framework within which manifest variables with different distributions in the exponential family can be analyzed with a latent trait model. Presents a unified maximum likelihood method for estimating the parameters of the generalized latent trait model and discusses the scoring of individuals on the latent dimensions.…

  20. Effect of chemical heat release in a temporally evolving mixing layer

    NASA Technical Reports Server (NTRS)

    Higuera, F. J.; Moser, R. D.

    1994-01-01

    Two-dimensional numerical simulations of a temporally evolving mixing layer with an exothermic infinitely fast diffusion flame between two unmixed reactants have been carried out in the limit of zero Mach number to study the effect of the heat release on the early stages of the evolution of the flow. Attention has been directed to relatively large values of the oxidizer-to-fuel mass stoichiometric ratio typical of hydrocarbon flames, and initial vorticity distributions thicker than the temperature and species distributions have been chosen to mimic the situation at the outlet of a jet. The results show that, during the stages of the evolution covered by the present simulations, enhancement of combustion occurs by local stretching of the flame without much augmentation of its area. The rate of product generation depends strongly on the initial conditions, which suggests the possibility of controlling the combustion by acting on the flow. Rollup and vortex amalgamation still occur in these reacting flows but are very much affected by the production of new vorticity by baroclinic torques. These torques lead to counter rotating vortex pairs around the flame and, more importantly, in thin layers of light fluid that leave the vicinity of the flame when the Kelvin-Helmholtz instability begins to develop. Propelled by the vortex pairs, these layers wind around, split on reaching high pressure regions, and originate new vortex pairs in a process that ends up building large-scale vortices with a vorticity distribution more complex than for a constant density fluid.

  1. α-Tocopherol-loaded niosome prepared by heating method and its release behavior.

    PubMed

    Basiri, Ladan; Rajabzadeh, Ghadir; Bostan, Aram

    2017-04-15

    α-Tocopherol-loaded niosome was developed using modified heating method. The influence of surfactants (Span60 and Tween60) in different mole ratios, presence or absence of cholesterol (Chol) and dicetyl phosphate (DCP) as well as different concentration of α-tocopherol (α-TOC) on mean size, polydispersity index, zeta potential and entrapment efficiency (EE) was evaluated. The results showed that α-TOC loaded niosomes exhibited a small mean size (73.85±0.6-186±0.58nm), narrow size distribution and high EE (61.13±0.52-98.92±0.92). By decreasing the HLB, the EE and stability of the niosomes increased. The DCP and Chol improved the physicochemical properties of niosomes. 3:1 mole ratio of Span 60:Tween 60, 4mg/ml of α-TOC and 25:12.5:2.5 mole ratio of surfactant:Chol:DCP was the optimum formulation in the encapsulation of α-TOC applying niosome system. The niosomes had sustained release profile in the simulated gastric and intestinal fluid.

  2. Stabilizing Alginate Confinement and Polymer Coating of CO-Releasing Molecules Supported on Iron Oxide Nanoparticles To Trigger the CO Release by Magnetic Heating.

    PubMed

    Meyer, Hajo; Winkler, Felix; Kunz, Peter; Schmidt, Annette M; Hamacher, Alexandra; Kassack, Matthias U; Janiak, Christoph

    2015-12-07

    Maghemite (Fe2O3) iron oxide nanoparticles (IONPs) were synthesized, modified with covalent surface-bound CO-releasing molecules of a tri(carbonyl)-chlorido-phenylalaninato-ruthenium(II) complex (CORM), and coated with a dextran polymer. The time- and temperature-dependent CO release from this CORM-3 analogue was followed by a myoglobin assay. A new measurement method for the myoglobin assay was developed, based on confining "water-soluble" polymer-coated Dextran500k@CORM@IONP particles in hollow spheres of nontoxic and easily prepared calcium alginate. Dropping a mixture of Dextran500k@CORM@IONP and sodium alginate into a CaCl2 solution leads to stable hollow spheres of Ca(2+) cross-linked alginate which contain the Dextran500k@CORM@IONP particles. This "alginate-method" (i) protects CORM-3 analogues from rapid CO-displacement reactions with a protein, (ii) enables a spatial separation of the CORM from its surrounding myoglobin assay with the alginate acting as a CO-permeable membrane, and (iii) allows the use of substances with high absorptivity (such as iron oxide nanoparticles) in the myoglobin assay without interference in the optical path of the UV cell. Embedding the CORM@IONP nanoparticles in the alginate vessel represents a compartmentation of the reactive component and allows for close contact with, yet facile separation from, the surrounding myoglobin assay. The half-life of the CO release from Dextran500k@CORM@IONP particles surrounded by alginate was determined to be 890 ± 70 min at 20 °C. An acceleration of the CO release occurs at higher temperature with a half-life of 172 ± 27 min at 37 °C and 45 ± 7 min at 50 °C. The CO release can be triggered in an alternating current magnetic field (31.7 kA m(-1), 247 kHz, 39.9 mT) through local magnetic heating of the susceptible iron oxide nanoparticles. With magnetic heating at 20 °C in the bulk solution, the half-life of CO release from Dextran500k@CORM@IONP particles decreased to 155 ± 18 min

  3. Numerical simulations on influence of urban land cover expansion and anthropogenic heat release on urban meteorological environment in Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Zhang, Ning; Wang, Xuemei; Chen, Yan; Dai, Wei; Wang, Xueyuan

    2016-11-01

    Urbanization is an extreme way in which human being changes the land use/land cover of the earth surface, and anthropogenic heat release occurs at the same time. In this paper, the anthropogenic heat release parameterization scheme in the Weather Research and Forecasting model is modified to consider the spatial heterogeneity of the release; and the impacts of land use change and anthropogenic heat release on urban boundary layer structure in the Pearl River Delta, China, are studied with a series of numerical experiments. The results show that the anthropogenic heat release contributes nearly 75 % to the urban heat island intensity in our studied period. The impact of anthropogenic heat release on near-surface specific humidity is very weak, but that on relative humidity is apparent due to the near-surface air temperature change. The near-surface wind speed decreases after the local land use is changed to urban type due to the increased land surface roughness, but the anthropogenic heat release leads to increases of the low-level wind speed and decreases above in the urban boundary layer because the anthropogenic heat release reduces the boundary layer stability and enhances the vertical mixing.

  4. Release behavior of non-network proteins and its relationship to the structure of heat-induced soy protein gels.

    PubMed

    Wu, Chao; Hua, Yufei; Chen, Yeming; Kong, Xiangzhen; Zhang, Caimeng

    2015-04-29

    Heat-induced soy protein gels were prepared by heating protein solutions at 12%, 15% ,or 18% for 0.5, 1.0, or 2.0 h. The release of non-network proteins from gel slices was conducted in 10 mM pH 7.0 sodium phosphate buffer. SDS-PAGE and diagonal electrophoresis demonstrated that the released proteins consisted of undenatured AB subunits and denatured proteins including monomers of A polypeptides, disulfide bond linked dimers, trimers, and polymers of A polypeptides, and an unidentified 15 kDa protein. SEC-HPLC analysis of non-network proteins revealed three major protein peaks, with molecular weights of approximately 253.9, 44.8, and 9.7 kDa. The experimental data showed that the time-dependent release of the three fractions from soy protein gels fit Fick's second law. An increasing protein concentration or heating time resulted in a decrease in diffusion coefficients of non-network proteins. A power law expression was used to describe the relationship between non-network protein diffusion coefficient and molecular weight, for which the exponent (α) shifted to higher value with an increase in protein concentration or heating time, indicating that a more compact gel structure was formed.

  5. Smoothing HCCI heat release with vaporization-cooling-induced thermal stratification using ethanol.

    SciTech Connect

    Dec, John E.; Sjoberg, Carl-Magnus G.

    2010-12-01

    Ethanol and ethanol/gasoline blends are being widely considered as alternative fuels for light-duty automotive applications. At the same time, HCCI combustion has the potential to provide high efficiency and ultra-low exhaust emissions. However, the application of HCCI is typically limited to low and moderate loads because of unacceptably high heat-release rates (HRR) at higher fueling rates. This work investigates the potential of lowering the HCCI HRR at high loads by using partial fuel stratification to increase the in-cylinder thermal stratification. This strategy is based on ethanol's high heat of vaporization combined with its true single-stage ignition characteristics. Using partial fuel stratification, the strong fuel-vaporization cooling produces thermal stratification due to variations in the amount of fuel vaporization in different parts of the combustion chamber. The low sensitivity of the autoignition reactions to variations of the local fuel concentration allows the temperature variations to govern the combustion event. This results in a sequential autoignition event from leaner and hotter zones to richer and colder zones, lowering the overall combustion rate compared to operation with a uniform fuel/air mixture. The amount of partial fuel stratification was varied by adjusting the fraction of fuel injected late to produce stratification, and also by changing the timing of the late injection. The experiments show that a combination of 60-70% premixed charge and injection of 30-40 % of the fuel at 80{sup o}CA before TDC is effective for smoothing the HRR. With CA50 held fixed, this increases the burn duration by 55% and reduces the maximum pressure-rise rate by 40%. Combustion stability remains high but engine-out NO{sub x} has to be monitored carefully. For operation with strong reduction of the peak HRR, ISNO{sub x} rises to around 0.20 g/kWh for an IMEP{sub g} of 440 kPa. The single-cylinder HCCI research engine was operated naturally aspirated

  6. Assessment of Heat Resistance of Bacterial Spores from Food Product Isolates by Fluorescence Monitoring of Dipicolinic Acid Release

    PubMed Central

    Kort, Remco; O'Brien, Andrea C.; van Stokkum, Ivo H. M.; Oomes, Suus J. C. M.; Crielaard, Wim; Hellingwerf, Klaas J.; Brul, Stanley

    2005-01-01

    This study is aimed at the development and application of a convenient and rapid optical assay to monitor the wet-heat resistance of bacterial endospores occurring in food samples. We tested the feasibility of measuring the release of the abundant spore component dipicolinic acid (DPA) as a probe for heat inactivation. Spores were isolated from the laboratory type strain Bacillus subtilis 168 and from two food product isolates, Bacillus subtilis A163 and Bacillus sporothermodurans IC4. Spores from the lab strain appeared much less heat resistant than those from the two food product isolates. The decimal reduction times (D values) for spores from strains 168, A163, and IC4 recovered on Trypticase soy agar were 1.4, 0.7, and 0.3 min at 105°C, 120°C, and 131°C, respectively. The estimated Z values were 6.3°C, 6.1°C, and 9.7°C, respectively. The extent of DPA release from the three spore crops was monitored as a function of incubation time and temperature. DPA concentrations were determined by measuring the emission at 545 nm of the fluorescent terbium-DPA complex in a microtiter plate fluorometer. We defined spore heat resistance as the critical DPA release temperature (Tc), the temperature at which half the DPA content has been released within a fixed incubation time. We found Tc values for spores from Bacillus strains 168, A163, and IC4 of 108°C, 121°C, and 131°C, respectively. On the basis of these observations, we developed a quantitative model that describes the time and temperature dependence of the experimentally determined extent of DPA release and spore inactivation. The model predicts a DPA release rate profile for each inactivated spore. In addition, it uncovers remarkable differences in the values for the temperature dependence parameters for the rate of spore inactivation, DPA release duration, and DPA release delay. PMID:16000762

  7. Solar heating system

    DOEpatents

    Schreyer, James M.; Dorsey, George F.

    1982-01-01

    An improved solar heating system in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75.degree. to 180.degree. F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing and releasing heat for distribution.

  8. Improved solar heating systems

    DOEpatents

    Schreyer, J.M.; Dorsey, G.F.

    1980-05-16

    An improved solar heating system is described in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75 to 180/sup 0/F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing ad releasing heat for distribution.

  9. On numerical model of time-dependent processes in three-dimensional porous heat-releasing objects

    NASA Astrophysics Data System (ADS)

    Lutsenko, Nickolay A.

    2016-10-01

    The gas flows in the gravity field through porous objects with heat-releasing sources are investigated when the self-regulation of the flow rate of the gas passing through the porous object takes place. Such objects can appear after various natural or man-made disasters (like the exploded unit of the Chernobyl NPP). The mathematical model and the original numerical method, based on a combination of explicit and implicit finite difference schemes, are developed for investigating the time-dependent processes in 3D porous energy-releasing objects. The advantage of the numerical model is its ability to describe unsteady processes under both natural convection and forced filtration. The gas cooling of 3D porous objects with different distribution of heat sources is studied using computational experiment.

  10. Comparison of two interferon-gamma release assays (QuantiFERON-TB Gold In-Tube and T-SPOT.TB) in testing for latent tuberculosis infection among HIV-infected adults.

    PubMed

    Sultan, B; Benn, P; Mahungu, T; Young, M; Mercey, D; Morris-Jones, S; Miller, R F

    2013-10-01

    There is currently no 'gold standard' for diagnosis of latent tuberculosis infection (LTBI), and both the tuberculin skin test and interferon-gamma release assays (IGRAs) are used for diagnosis; the latter have a higher sensitivity than tuberculin skin tests for diagnosis of LTBI in HIV-infected individuals with lower CD4 counts. No evidence base exists for selection of IGRA methodology to identify LTBI among human immunodeficiency virus-infected patients in the UK. We prospectively evaluated two commercially available IGRA methods (QuantiFERON-TB Gold In Tube [QFG] and T-SPOT.TB) for testing LTBI among HIV-infected patients potentially nosocomially exposed to an HIV-infected patient with 'smear-positive' pulmonary tuberculosis. Among the exposed patients median CD4 count was 550 cells/µL; 105 (90%) of 117 were receiving antiretroviral therapy, of who 104 (99%) had an undetectable plasma HIV load. IGRAs were positive in 12 patients (10.3%); QFG positive in 11 (9.4%) and T-SPOT.TB positive in six (5.1%); both IGRAs were positive in five patients (4.3%). There was one indeterminate QFG and one borderline T-SPOT.TB result. Concordance between the two IGRAs was moderate (κ = 0.56, 95% confidence interval = 0.27-0.85). IGRAs were positive in only 4 (29%) of 14 patients with previous culture-proven tuberculosis. No patient developed tuberculosis during 20 months of follow-up.

  11. Two-time correlation of heat release rate and spectrum of combustion noise from turbulent premixed flames

    NASA Astrophysics Data System (ADS)

    Liu, Yu

    2015-09-01

    The spectral characteristics of combustion noise are dictated by the temporal correlation of the overall change of heat release rate fluctuations which has not received sufficient attention in prior studies. In this work, the two-time correlation of the volumetric heat release rate fluctuations within the flame brush and its role in modeling combustion noise spectrum are investigated by analyzing direct numerical simulation (DNS) data of turbulent premixed V-flames. This two-time correlation can be well represented by Gaussian-type functions and it captures the slow global variation of the fluctuating heat release rate and hence the low-frequency noise sources of unsteady combustion. The resulting correlation model is applied to predict the far-field noise spectrum from test open flames, and different reference time scales are used to scale this correlation from the DNS data to the test flames. The comparison between predictions and measurements indicates that the correlation models of all reference time scales are capable of reproducing the essential spectral shape including the low- and high-frequency dependencies. Reasonable agreement in the peak frequency, peak sound pressure level, and the Strouhal number scaling of peak frequency is also achieved for two turbulent time scales. A promising convective time scale shows great potential for characterizing the spectral features, yet its predictive capabilities are to be further verified through a longer DNS signal of a bounded flame configuration.

  12. The pH effect of solvent in silanization on fluoride released and mechanical properties of heat-cured acrylic resin containing fluoride-releasing filler.

    PubMed

    Nakornchai, Natha; Arksornnukit, Mansuang; Kamonkhantikul, Krid; Takahashi, Hidekazu

    2016-01-01

    This study aimed to evaluate the effect of an acidic-adjusted pH of solvent in silanization on the amount of fluoride released and mechanical properties of heat-cured acrylic resin containing a silanized fluoride-releasing filler. The experimental groups were divided into 4 groups; non-silanized, acidic-adjusted pH, non-adjusted pH, and no filler as control. For fluoride measurement, each specimen was placed in deionized water which was changed every day for 7 days, every week for 7 weeks and measured. The flexural strength and flexural modulus were evaluated after aging for 48 h, 1, and 2 months. Two-way ANOVA indicated significant differences among groups, storage times, and its interaction in fluoride measurement and flexural modulus. For flexural strength, there was significant difference only among groups. Acidic-adjusted pH of solvent in silanization enhanced the amount of fluoride released from acrylic resin, while non-adjusted pH of solvent exhibited better flexural strength of acrylic resin.

  13. Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models

    SciTech Connect

    Tao, Wei-Kuo; Houze, Robert, A., Jr.; Zeng, Xiping

    2013-03-14

    were compared with three reanalyses (MERRA, ERA-Interim and CFSR). Although the MMF tends to produce a higher precipitation rate over some topical regions, it actually well captures the variations in the zonal and meridional means. Among the three reanalyses, ERA-Interim seems to have values close to those of the satellite retrievals especially for GPCP. It is interesting to note that the MMF obtained the best results in the rain forest of Africa even better than those of CFSR and ERA-Interim, when compared to CMORPH. MERRA fails to capture the precipitation in this region. We are now collaborating with Steve Rutledge (CSU) to validate the model results for AMMA 6. MC3E and the diurnal variation of precipitation processes The Midlatitude Continental Convective Clouds Experiment (MC3E) was a joint field campaign between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the NASA Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. It took place in central Oklahoma during the period April 22 _ June 6, 2011. Some of its major objectives involve the use of CRMs in precipitation science such as: (1) testing the fidelity of CRM simulations via intensive statistical comparisons between simulated and observed cloud properties and latent heating fields for a variety of case types, (2) establishing the limits of CRM space-time integration capabilities for quantitative precipitation estimates, and (3) supporting the development and refinement of physically-based GMI, DPR, and DPR-GMI combined retrieval algorithms using ground-based GPM GV Ku-Ka band radar and CRM simulations. The NASA unified WRF model (nu-WRF) was used for real time forecasts during the field campaign, and ten precipitation events were selected for post mission simulations. These events include well-organized squall lines, scattered storms and quasi-linear storms. A paper focused on the diurnal variation of precipitation will be

  14. LATENT LIFE OF ARTERIES.

    PubMed

    Carrel, A

    1910-07-23

    When a segment of artery, killed by heat, formalin or glycerin is transplanted, it undergoes a rapid degeneration. Its muscle fibers disappear while the tissue of the host reacts by building a new wall of connective tissue. When the transplanted vessel has been preserved in a condition of latent life, no degeneration of the wall occurs, or the wall undergoes only partial degeneration. The muscle fibers can keep their normal appearance, even for a long time after the operation. It is, therefore, demonstrated that arteries can be preserved outside of the body in a condition of unmanifested actual life. The best method of preservation consists of placing the vessels, immersed in vaselin, in an ice box, the temperature of which is slightly above the freezing point. From a surgical standpoint, the transplantation of preserved vessels can be used with some safety. When the arteries were kept in defibrinated blood or vaselin and in cold storage, the proportion of positive results was 75 and 80 per cent., and this can probably be increased.

  15. The effectiveness of organic PCM based on lauric acid from coconut oil and inorganic PCM based on salt hydrate CaCl2.6H2o as latent heat energy storage system in Indonesia

    NASA Astrophysics Data System (ADS)

    U, Sri Rahayu A.; Putri, Widya A.; Sutjahja, I. M.; Kurnia, D.; Wonorahardjo, S.

    2016-08-01

    A latent heat energy storage system utilizing phase change materials (PCM) is an alternative strategy to reduce the use of Air Conditioning (AC) system in big cities in Indonesia in order for energy conservation in the future. In this research we used two kinds of materials, namely organic PCM based on lauric acid from coconut oil (CO) and inorganic PCM based on salt hydrate CaCl2.6H2O, because they have thermophysical parameters suitable for human's thermal comfort application in the building. The CO which contained more than 50% lauric acid has the melting temperature (Tm ) of about 26 °C and heat entalphy (ΔH) around 103 kJ/kg, while CaCl2.6H2O has the melting point of 29 °C and heat entalphy of 190 kJ/kg. In this paper we report the effectiveness of those two kinds of PCM in reducing the air temperature as one of some criteria for human's thermal comfort. The experiments were performed in a close and adiabatic room and the time-temperature measurements were done automatically using Arduino microcontroller and LM35 temperature sensor connected to the PC.

  16. Latent Period of Relaxation.

    PubMed

    Kobayashi, M; Irisawa, H

    1961-10-27

    The latent period of relaxation of molluscan myocardium due to anodal current is much longer than that of contraction. Although the rate and the grade of relaxation are intimately related to both the stimulus condition and the muscle tension, the latent period of relaxation remains constant, except when the temperature of the bathing fluid is changed.

  17. Latent fingerprint matching.

    PubMed

    Jain, Anil K; Feng, Jianjiang

    2011-01-01

    Latent fingerprint identification is of critical importance to law enforcement agencies in identifying suspects: Latent fingerprints are inadvertent impressions left by fingers on surfaces of objects. While tremendous progress has been made in plain and rolled fingerprint matching, latent fingerprint matching continues to be a difficult problem. Poor quality of ridge impressions, small finger area, and large nonlinear distortion are the main difficulties in latent fingerprint matching compared to plain or rolled fingerprint matching. We propose a system for matching latent fingerprints found at crime scenes to rolled fingerprints enrolled in law enforcement databases. In addition to minutiae, we also use extended features, including singularity, ridge quality map, ridge flow map, ridge wavelength map, and skeleton. We tested our system by matching 258 latents in the NIST SD27 database against a background database of 29,257 rolled fingerprints obtained by combining the NIST SD4, SD14, and SD27 databases. The minutiae-based baseline rank-1 identification rate of 34.9 percent was improved to 74 percent when extended features were used. In order to evaluate the relative importance of each extended feature, these features were incrementally used in the order of their cost in marking by latent experts. The experimental results indicate that singularity, ridge quality map, and ridge flow map are the most effective features in improving the matching accuracy.

  18. National Athletic Trainers' Association Releases New Guidelines for Exertional Heat Illnesses: What School Nurses Need to Know.

    PubMed

    VanScoy, Rachel M; DeMartini, Julie K; Casa, Douglas J

    2016-05-01

    Exertional heat illnesses (EHI) occur in various populations and settings. Within a school setting, there are student athletes who take part in physical activity where the risk of EHI is increased. The National Athletic Trainers' Association (NATA) released an updated position statement on EHI in September of 2015. This article is a summary of the position statement. The sports medicine team, including school nurses and athletic trainers, provides quality health care to these physically active individuals. Thus, it is important for school nurses to understand the prevention, recognition, and treatment of EHI.

  19. Custom-designed Laser-based Heating Apparatus for Triggered Release of Cisplatin from Thermosensitive Liposomes with Magnetic Resonance Image Guidance.

    PubMed

    Dou, Yannan N; Weersink, Robert A; Foltz, Warren D; Zheng, Jinzi; Chaudary, Naz; Jaffray, David A; Allen, Christine

    2015-12-13

    Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e., gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.

  20. Maturation of Released Spores Is Necessary for Acquisition of Full Spore Heat Resistance during Bacillus subtilis Sporulation ▿

    PubMed Central

    Sanchez-Salas, Jose-Luis; Setlow, Barbara; Zhang, Pengfei; Li, Yong-qing; Setlow, Peter

    2011-01-01

    The first ∼10% of spores released from sporangia (early spores) during Bacillus subtilis sporulation were isolated, and their properties were compared to those of the total spores produced from the same culture. The early spores had significantly lower resistance to wet heat and hypochlorite than the total spores but identical resistance to dry heat and UV radiation. Early and total spores also had the same levels of core water, dipicolinic acid, and Ca and germinated similarly with several nutrient germinants. The wet heat resistance of the early spores could be increased to that of total spores if early spores were incubated in conditioned sporulation medium for ∼24 h at 37°C (maturation), and some hypochlorite resistance was also restored. The maturation of early spores took place in pH 8 buffer with Ca2+ but was blocked by EDTA; maturation was also seen with early spores of strains lacking the CotE protein or the coat-associated transglutaminase, both of which are needed for normal coat structure. Nonetheless, it appears to be most likely that it is changes in coat structure that are responsible for the increased resistance to wet heat and hypochlorite upon early spore maturation. PMID:21821751

  1. Small heat shock proteins can release light dependence of tobacco seed during germination.

    PubMed

    Koo, Hyun Jo; Park, Soo Min; Kim, Keun Pill; Suh, Mi Chung; Lee, Mi Ok; Lee, Seong-Kon; Xinli, Xia; Hong, Choo Bong

    2015-03-01

    Small heat shock proteins (sHSPs) function as ATP-independent molecular chaperones, and although the production and function of sHSPs have often been described under heat stress, the expression and function of sHSPs in fundamental developmental processes, such as pollen and seed development, have also been confirmed. Seed germination involves the breaking of dormancy and the resumption of embryo growth that accompany global changes in transcription, translation, and metabolism. In many plants, germination is triggered simply by imbibition of water; however, different seeds require different conditions in addition to water. For small-seeded plants, like Arabidopsis (Arabidopsis thaliana), lettuce (Lactuca sativa), tomato (Solanum lycopersicum), and tobacco (Nicotiana tabacum), light is an important regulator of seed germination. The facts that sHSPs accumulate during seed development, sHSPs interact with various client proteins, and seed germination accompanies synthesis and/or activation of diverse proteins led us to investigate the role of sHSPs in seed germination, especially in the context of light dependence. In this study, we have built transgenic tobacco plants that ectopically express sHSP, and the effect was germination of the seeds in the dark. Administering heat shock to the seeds also resulted in the alleviation of light dependence during seed germination. Subcellular localization of ectopically expressed sHSP was mainly observed in the cytoplasm, whereas heat shock-induced sHSPs were transported to the nucleus. We hypothesize that ectopically expressed sHSPs in the cytoplasm led the status of cytoplasmic proteins involved in seed germination to function during germination without additional stimulus and that heat shock can be another signal that induces seed germination.

  2. Global Atmospheric Heat Distributions Observed from Space

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Fan, Tai-Fang

    2009-01-01

    This study focuses on the observations of global atmospheric heat distributions using satellite measurements. Major heat components such as radiation energy, latent heat and sensible heat are considered. The uncertainties and error sources are assessed. Results show that the atmospheric heat is basically balanced, and the observed patterns of radiation and latent heat from precipitation are clearly related to general circulation.

  3. The Effect of Spray Initial Conditions on Heat Release and Emissions in LDI CFD Calculations (Preprint)

    DTIC Science & Technology

    2008-06-01

    equations, which are then advanced temporally by an explicit 4-stage Runge-Kutta scheme. For low Mach number compressible flow, a pre-conditioning is...currently valid OMB control number . PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 05-06-2008 2. REPORT TYPE...Technical Memo 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER The Effect of Spray Initial Conditions on Heat

  4. Mass spectrometric analysis of the volatiles released by heating or crushing rocks

    NASA Technical Reports Server (NTRS)

    Barker, C.; Sommer, M. A.

    1973-01-01

    Vacuum extraction with subsequent mass spectrometric analysis of evolved volatiles was selected as the analytical procedure. The high-vacuum gas-handling system was constructed of stainless steel. The system was completely free from mercury, grease, or volatile organic materials. The furnace for heating the samples is discussed together with the high-vacuum crusher, the mass spectrometer, and approaches for water determination. The analytical procedure is considered, giving attention to the extraction of volatiles, adsorption studies, and the analysis of volatiles.

  5. Contribution of Interferon gamma release assays testing to the diagnosis of latent tuberculosis infection in HIV-infected patients: A comparison of QuantiFERON-TB Gold In Tube, T-SPOT.TB and tuberculin skin test

    PubMed Central

    2012-01-01

    Background Diagnosis and treatment of latent tuberculosis infection (LTBI) is the most effective strategy to control tuberculosis (TB) among patients with HIV infection. The tuberculin skin test (TST) was the only available method to identify LTBI. The aim of the present work was to evaluate the usefulness of the interferon-gamma release assays (IGRAs): QuantiFERON-tuberculosis (TB) Gold-In-Tube test (QFG) and T-SPOT.TB for the diagnosis of LTBI in a diverse cohort of HIV-infected patients. Methods A prospective study was carried out in consecutive patients cared for in a single institution in Spain from January 2009 to October 2010. IGRAs and TST were performed simultaneously. TST induration ≥ 5 mm was considered positive. Results QFG, T-SPOT.TB and TST were performed in 373 subjects. Median CD4 cell count was 470/μl with a median nadir of 150/μl. TST, QFG and T-SPOT.TB were positive in 13.3%, 7.5% and 18.5% cases respectively. Among 277 patients with neither past or current TB nor previous treatment for LTBI and who had TST results, a positive TST result was obtained in 20 (7.2%) cases. When adding QFG results to TST, there were a total of 26 (8.6%) diagnoses of LTBI. When the results of both IGRAs were added, the number of diagnoses increased to 54 (17.9%) (incremental difference: 10.7% [95% confidence interval [CI]:5.3-16.2%] [p < 0.001]), and when both IGRAs were added, the number of diagnoses reached 56 (18.5%) (incremental difference: 11.3% [95% CI:5.7%–16.9%] [p < 0.001]). Patients with a CD4 cell count greater than 500 cells/μl and prior stay in prison were more likely to have a diagnosis of LTBI by TST and/or QFG and/or T-SPOT.TB (adjusted odds ratio [aOR]: 3.8; 95% CI, 1.4 – 9.9; and aOR: 3.3; 95% CI, 1.3 – 8.3, respectively). Conclusions IGRAs were more sensitive than TST for diagnosis of M. tuberculosis infection in HIV-infected patients. Dual sequential testing with TST and IGRAs may be the optimal approach for LTBI screening in this

  6. Effect of Wool Components in Pile Fabrics on Water Vapor Sorption, Heat Release, and Humidity Buffering

    DTIC Science & Technology

    2008-05-01

    extreme step change in relative humidity, the Knit C fabric (Wool/ PLA blend sample with highest wool content) will provide about twice the energy...difference between test results of varying fabric orientation. -5.0 -2.5 0 2.5 5.0 0 100 200 300 400 Knit C Wool/ PLA Blend (Wool Away From Body...Knit CWool/ PLA Blend (Wool Towards Body) Setpoint #6 (99% r.h.) Sorption Flow = 0.5 L/min Heat Flow into Body Setpoint #5 (1% r.h.) Desorption

  7. Effect of ATP on the release of hsp 70 and hsp 40 from the nucleus in heat-shocked HeLa cells.

    PubMed

    Ohtsuka, K; Utsumi, K R; Kaneda, T; Hattori, H

    1993-12-01

    We have recently found a novel 40-kDa heat-shock protein (hsp 40) in mammalian and avian cells and reported that the N-terminal amino acid sequence of mammalian hsp 40 has homology with the bacterial DnaJ heat-shock protein. Also, hsp 40 has been shown to be translocated from the cytoplasm into the nuclei/nucleoli by heat shock and colocalized with hsc 70 (p73) in the nucleoli of exactly the same cells. We here investigated the effect of ATP on the release of hsp 70 (both constitutive p73 and inducible p72) and hsp 40 from the nuclei/nucleoli of heat-shocked HeLa cells which were permeabilized with Nonidet-P40 using immunofluorescence and immunoblotting. Hsp 70 in the nucleoli was released by the addition of ATP but not by ADP, GTP, nonhydrolyzable ATP, nor high salt buffer. In contrast, hsp 40 was not released from the nucleoli with any of these treatments or any combination of these treatments. Thus, hsp 40 might dissociate spontaneously from the nucleoli after hsp 70 has been released in an ATP-dependent manner. Using cell fractionation methods, we showed that while the majority of hsp 40 is localized in the cytoplasm, a small portion of it is located in the microsome fraction in non-heat-shocked control cells and in cells which recovered from heat shock.

  8. Potentiation of latent inhibition.

    PubMed

    Rodriguez, Gabriel; Hall, Geoffrey

    2008-07-01

    Rats were given exposure either to an odor (almond) or a compound of odor plus taste (almond plus saline), prior to training in which the odor served as the conditioned stimulus. It was found, for both appetitive and aversive procedures, that conditioning was retarded by preexposure (a latent inhibition effect), and the extent of the retardation was greater in rats preexposed to the compound (i.e., latent inhibition to the odor was potentiated by the presence of the taste). In contrast, the presence of the taste during conditioning itself overshadowed learning about the odor. We argue that the presence of the salient taste in compound with the odor enhances the rate of associative learning, producing a rapid loss in the associability of the odor. This loss of associability will generate both overshadowing and the potentiation of latent inhibition that is observed after preexposure to the compound.

  9. Laser‐Triggered Small Interfering RNA Releasing Gold Nanoshells against Heat Shock Protein for Sensitized Photothermal Therapy

    PubMed Central

    Wang, Zhaohui; Li, Siwen; Zhang, Min; Ma, Yi; Liu, Yuxi; Gao, Weidong; Zhang, Jiaqi

    2016-01-01

    The resistance of cancer cells to photothermal therapy is closely related to the overexpression of heat shock proteins (HSPs), which are abnormally upregulated when cells are under lethal stresses. Common strategies that use small molecule inhibitors against HSPs to enhance hyperthermia effect lack spatial and temporal control of drug release, leading to unavoidable systemic toxicity. Herein, a versatile photothermal platform is developed which is composed of a hollow gold nanoshell core densely packed with small interfering RNAs against heat shock protein 70 (Hsp70). Upon near infrared light irradiation, the small interfering RNAs can detach from gold surface specifically and escape from endosomes for Hsp70 silencing. Meanwhile, the temperature increases for hyperthermia therapy due to the high photothermal efficiency of the nanoshells. Efficient downregulation of Hsp70 after light activation is achieved in vitro and in vivo. Ultimately, the light‐controlled dual functional nanosystem, with the effects of Hsp70 silencing and temperature elevation, results in sensitized photothermal therapy in nude mice model under mild temperature. This strategy smartly combines the localized photothermal therapy with controlled Hsp70 silencing, and has great potential for clinical translation with a simple and easily controlled structure. PMID:28251053

  10. Laser-Triggered Small Interfering RNA Releasing Gold Nanoshells against Heat Shock Protein for Sensitized Photothermal Therapy.

    PubMed

    Wang, Zhaohui; Li, Siwen; Zhang, Min; Ma, Yi; Liu, Yuxi; Gao, Weidong; Zhang, Jiaqi; Gu, Yueqing

    2017-02-01

    The resistance of cancer cells to photothermal therapy is closely related to the overexpression of heat shock proteins (HSPs), which are abnormally upregulated when cells are under lethal stresses. Common strategies that use small molecule inhibitors against HSPs to enhance hyperthermia effect lack spatial and temporal control of drug release, leading to unavoidable systemic toxicity. Herein, a versatile photothermal platform is developed which is composed of a hollow gold nanoshell core densely packed with small interfering RNAs against heat shock protein 70 (Hsp70). Upon near infrared light irradiation, the small interfering RNAs can detach from gold surface specifically and escape from endosomes for Hsp70 silencing. Meanwhile, the temperature increases for hyperthermia therapy due to the high photothermal efficiency of the nanoshells. Efficient downregulation of Hsp70 after light activation is achieved in vitro and in vivo. Ultimately, the light-controlled dual functional nanosystem, with the effects of Hsp70 silencing and temperature elevation, results in sensitized photothermal therapy in nude mice model under mild temperature. This strategy smartly combines the localized photothermal therapy with controlled Hsp70 silencing, and has great potential for clinical translation with a simple and easily controlled structure.

  11. Latent Variable Interaction Modeling.

    ERIC Educational Resources Information Center

    Schumacker, Randall E.

    2002-01-01

    Used simulation to study two different approaches to latent variable interaction modeling with continuous observed variables: (1) a LISREL 8.30 program and (2) data analysis through PRELIS2 and SIMPLIS programs. Results show that parameter estimation was similar but standard errors were different. Discusses differences in ease of implementation.…

  12. Latent Semantic Analysis.

    ERIC Educational Resources Information Center

    Dumais, Susan T.

    2004-01-01

    Presents a literature review that covers the following topics related to Latent Semantic Analysis (LSA): (1) LSA overview; (2) applications of LSA, including information retrieval (IR), information filtering, cross-language retrieval, and other IR-related LSA applications; (3) modeling human memory, including the relationship of LSA to other…

  13. Extending periodic eddy covariance latent heat fluxes through tree sap-flow measurements to estimate long-term total evaporation in a peat swamp forest

    NASA Astrophysics Data System (ADS)

    Clulow, A. D.; Everson, C. S.; Mengistu, M. G.; Price, J. S.; Nickless, A.; Jewitt, G. P. W.

    2015-05-01

    A combination of measurement and modelling was used to find a pragmatic solution to estimate the annual total evaporation from the rare and indigenous Nkazana Peat Swamp Forest (PSF) on the east coast of Southern Africa to improve the water balance estimates within the area. Actual total evaporation (ETa) was measured during three window periods (between 7 and 9 days each) using an eddy covariance (EC) system on a telescopic mast above the forest canopy. Sap flows of an understory tree and an emergent tree were measured using a low-maintenance heat pulse velocity system for an entire hydrological year (October 2009 to September 2010). An empirical model was derived, describing the relationship between ETa from the Nkazana PSF and sap-flow measurements. These overlapped during two of the window periods (R2 = 0.92 and 0.90), providing hourly estimates of ETa from the Nkazana PSF for a year, totalling 1125 mm (while rainfall was 650 mm). In building the empirical model, it was found that to include the understory tree sap flow provided no benefit to the model performance. In addition, the relationship between the emergent tree sap flow with ETa between the two field campaigns was consistent and could be represented by a single empirical model (R2 = 0.90; RMSE = 0.08 mm h-1). During the window periods of EC measurement, no single meteorological variable was found to describe the Nkazana PSF ETa satisfactorily. However, in terms of evaporation models, the hourly FAO Penman-Monteith reference evaporation (ETo) best described ETa during the August 2009 (R2 = 0.75), November 2009 (R2 = 0.85) and March 2010 (R2 = 0.76) field campaigns, compared to the Priestley-Taylor potential evaporation (ETp) model (R2 = 0.54, 0.74 and 0.62 during the respective field campaigns). From the extended record of ETa (derived in this study from sap flow) and ETo, a monthly crop factor (Kc) was derived for the Nkazana PSF, providing a method of estimating long-term swamp forest water-use from

  14. Partial fuel stratification to control HCCI heat release rates : fuel composition and other factors affecting pre-ignition reactions of two-stage ignition fuels.

    SciTech Connect

    Dec, John E.; Sjoberg, Carl-Magnus G.; Cannella, William; Yang, Yi; Dronniou, Nicolas

    2010-11-01

    Homogeneous charge compression ignition (HCCI) combustion with fully premixed charge is severely limited at high-load operation due to the rapid pressure-rise rates (PRR) which can lead to engine knock and potential engine damage. Recent studies have shown that two-stage ignition fuels possess a significant potential to reduce the combustion heat release rate, thus enabling higher load without knock.

  15. Controlling Heat Release from a Close-Packed Bisazobenzene-Reduced-Graphene-Oxide Assembly Film for High-Energy Solid-State Photothermal Fuels.

    PubMed

    Zhao, Xiaoze; Feng, Yiyu; Qin, Chengqun; Yang, Weixiang; Si, Qianyu; Feng, Wei

    2017-04-10

    A closed-cycle system for light-harvesting, storage, and heat release is important for utilizing and managing renewable energy. However, combining a high-energy, stable photochromic material with a controllable trigger for solid-state heat release remains a great challenge for developing photothermal fuels (PTFs). This paper presents a uniform PTF film fabricated by the assembly of close-packed bisazobenzene (bisAzo) grafted onto reduced graphene oxide (rGO). The assembled rGO-bisAzo template exhibited a high energy density of 131 Wh kg(-1) and a long half-life of 37 days owing to inter- or intramolecular H-bonding and steric hindrance. The rGO-bisAzo PTF film released and accumulated heat to realize a maximum temperature difference (DT) of 15 °C and a DT of over 10 °C for 30 min when the temperature difference of the environment was greater than100 °C. Controlling heat release in the solid-state assembly paves the way to develop highly efficient and high-energy PTFs for a multitude of applications.

  16. Thermally Stable, Latent Olefin Metathesis Catalysts

    PubMed Central

    Thomas, Renee M.; Fedorov, Alexey; Keitz, Benjamin K.

    2011-01-01

    Highly thermally stable N-aryl,N-alkyl N-heterocyclic carbene (NHC) ruthenium catalysts were designed and synthesized for latent olefin metathesis. These catalysts showed excellent latent behavior toward metathesis reactions, whereby the complexes were inactive at ambient temperature and initiated at elevated temperatures, a challenging property to achieve with second generation catalysts. A sterically hindered N-tert-butyl substituent on the NHC ligand of the ruthenium complex was found to induce latent behavior toward cross-metathesis reactions, and exchange of the chloride ligands for iodide ligands was necessary to attain latent behavior during ring-opening metathesis polymerization (ROMP). Iodide-based catalysts showed no reactivity toward ROMP of norbornene-derived monomers at 25 °C, and upon heating to 85 °C gave complete conversion of monomer to polymer in less than 2 hours. All of the complexes were very stable to air, moisture, and elevated temperatures up to at least 90 °C, and exhibited a long catalyst lifetime in solution at elevated temperatures. PMID:22282652

  17. Radio-frequency triggered heating and drug release using doxorubicin-loaded LSMO nanoparticles for bimodal treatment of breast cancer.

    PubMed

    Kulkarni, Vaishnavi M; Bodas, Dhananjay; Dhoble, Deepa; Ghormade, Vandana; Paknikar, Kishore

    2016-09-01

    Radio-frequency responsive nanomaterials combined with drugs for simultaneous hyperthermia and drug delivery are potential anti-cancer agents. In this study, chitosan coated La0.7Sr0.3MnO3 nanoparticles (C-LSMO NPs) were synthesized and characterized by X-ray diffraction, dynamic light scattering, Fourier transform infra red spectroscopy, vibrating sample magnetometer, scanning electron and atomic force microscopy. Under low radio-frequency (365kHz, RF), C-LSMO NPs (90nm) showed good colloidal stability (+22mV), superparamagnetic nature (15.4 emu/g) and heating capacity (57.4W/g SAR value). Chitosan facilitated doxorubicin entrapment (76%) resulted in DC-LSMO NPs that showed drug release upon a 5min RF exposure. MCF-7 and MDA-MB-231 cancer cells responded to a 5min RF exposure in the presence of bimodal DC-LSMO NPs with a significant decrease in viability to 73% and 88% (Pearson correlation, r=1, P<0.01) respectively, as compared to hyperthermia alone. Internalization of DC-LSMO NPs via the endosomal pathway led to an efficient localization of doxorubicin within the cell nucleus. The ensuing DNA damage, heat shock protein induction, and caspase production triggered apoptotic cell death. Moreover, DC-LSMO NPs successfully restricted the migration of metastatic MDA-MB-231 cancer cells. These data suggest that DC-LSMO NPs are potential bimodal therapeutic agents for cancer treatment and hold promise against disease recurrence and drug resistance.

  18. Latent effects decision analysis

    DOEpatents

    Cooper, J. Arlin; Werner, Paul W.

    2004-08-24

    Latent effects on a system are broken down into components ranging from those far removed in time from the system under study (latent) to those which closely effect changes in the system. Each component is provided with weighted inputs either by a user or from outputs of other components. A non-linear mathematical process known as `soft aggregation` is performed on the inputs to each component to provide information relating to the component. This information is combined in decreasing order of latency to the system to provide a quantifiable measure of an attribute of a system (e.g., safety) or to test hypotheses (e.g., for forensic deduction or decisions about various system design options).

  19. The invasion of non-native grasses into California grasslands has caused a shift in energy partitioning between latent and sensible heat flux, reduced albedo and higher surface temperatures

    NASA Astrophysics Data System (ADS)

    Koteen, L. E.; Harte, J.; Baldocchi, D. D.

    2012-12-01

    of latent to sensible heat flux is higher where native perennial grasses are found, particularly in wet years. Annual sums of total evaporation are likewise higher in native-dominated regions, and soil moisture is lower relative to non-natives in the deep soil. We also found that PAR albedo is lower in native grasslands compared to non-natives during significant portions of the year, and corresponding to the hotter months. In all, our findings indicate that the non-native annual grasses which now dominate California grasslands, promote conditions that support higher surface temperatures relative to native perennial grasses.

  20. Engine Operating Conditions and Fuel Properties on Pre-Spark Heat Release and SPI Promotion in SI Engines

    SciTech Connect

    Splitter, Derek A; Kaul, Brian C; Szybist, James P; Jatana, Gurneesh S

    2017-01-01

    This work explores the dependence of fuel ignition delay on stochastic pre-ignition (SPI). Findings are based on bulk gas thermodynamic state, where the effects of kinetically controlled bulk gas pre-spark heat release (PSHR) are correlated to SPI tendency and magnitude. Specifically, residual gas and low temperature PSHR chemistry effects and observations are explored, which are found to be indicative of bulk gas conditions required for strong SPI events. Analyzed events range from non-knocking SPI to knocking SPI and even detonation SPI events in excess of 325 bar peak cylinder pressure. The work illustrates that singular SPI event count and magnitude are found to be proportional to PSHR of the bulk gas mixture and residual gas fraction. Cycle-to-cycle variability in trapped residual mass and temperature are found to impose variability in singular SPI event count and magnitude. However, clusters and short lived bursts of multiple SPI events are found to better correlate with fuel-wall interaction. The results highlight the interplay of bulk gas thermodynamics and SPI ignition source, on SPI event magnitude and cluster tendency. Moreover, the results highlight fundamental fuel reactivity and associated hypersensitivity to operating conditions at SPI prone operating conditions.

  1. Latent heat characteristics of biobased oleochemical carbonates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oleochemical carbonates represent biobased materials that can be readily prepared through a carbonate interchange reaction between renewably available C10-C18 fatty alcohols. Although these carbonates have commercial use in cosmetics and lubricant applications, they have not been examined as phase ...

  2. Cyclic ADP-Ribose and Heat Regulate Oxytocin Release via CD38 and TRPM2 in the Hypothalamus during Social or Psychological Stress in Mice

    PubMed Central

    Zhong, Jing; Amina, Sarwat; Liang, Mingkun; Akther, Shirin; Yuhi, Teruko; Nishimura, Tomoko; Tsuji, Chiharu; Tsuji, Takahiro; Liu, Hong-Xiang; Hashii, Minako; Furuhara, Kazumi; Yokoyama, Shigeru; Yamamoto, Yasuhiko; Okamoto, Hiroshi; Zhao, Yong Juan; Lee, Hon Cheung; Tominaga, Makoto; Lopatina, Olga; Higashida, Haruhiro

    2016-01-01

    Hypothalamic oxytocin (OT) is released into the brain by cyclic ADP-ribose (cADPR) with or without depolarizing stimulation. Previously, we showed that the intracellular free calcium concentration ([Ca2+]i) that seems to trigger OT release can be elevated by β-NAD+, cADPR, and ADP in mouse oxytocinergic neurons. As these β-NAD+ metabolites activate warm-sensitive TRPM2 cation channels, when the incubation temperature is increased, the [Ca2+]i in hypothalamic neurons is elevated. However, it has not been determined whether OT release is facilitated by heat in vitro or hyperthermia in vivo in combination with cADPR. Furthermore, it has not been examined whether CD38 and TRPM2 exert their functions on OT release during stress or stress-induced hyperthermia in relation to the anxiolytic roles and social behaviors of OT under stress conditions. Here, we report that OT release from the isolated hypothalami of male mice in culture was enhanced by extracellular application of cADPR or increasing the incubation temperature from 35°C to 38.5°C, and simultaneous stimulation showed a greater effect. This release was inhibited by a cADPR-dependent ryanodine receptor inhibitor and a nonspecific TRPM2 inhibitor. The facilitated release by heat and cADPR was suppressed in the hypothalamus isolated from CD38 knockout mice and CD38- or TRPM2-knockdown mice. In the course of these experiments, we noted that OT release differed markedly between individual mice under stress with group housing. That is, when male mice received cage-switch stress and eliminated due to their social subclass, significantly higher levels of OT release were found in subordinates compared with ordinates. In mice exposed to anxiety stress in an open field, the cerebrospinal fluid (CSF) OT level increased transiently at 5 min after exposure, and the rectal temperature also increased from 36.6°C to 37.8°C. OT levels in the CSF of mice with lipopolysaccharide-induced fever (+0.8°C) were higher than those

  3. Cyclic ADP-Ribose and Heat Regulate Oxytocin Release via CD38 and TRPM2 in the Hypothalamus during Social or Psychological Stress in Mice.

    PubMed

    Zhong, Jing; Amina, Sarwat; Liang, Mingkun; Akther, Shirin; Yuhi, Teruko; Nishimura, Tomoko; Tsuji, Chiharu; Tsuji, Takahiro; Liu, Hong-Xiang; Hashii, Minako; Furuhara, Kazumi; Yokoyama, Shigeru; Yamamoto, Yasuhiko; Okamoto, Hiroshi; Zhao, Yong Juan; Lee, Hon Cheung; Tominaga, Makoto; Lopatina, Olga; Higashida, Haruhiro

    2016-01-01

    Hypothalamic oxytocin (OT) is released into the brain by cyclic ADP-ribose (cADPR) with or without depolarizing stimulation. Previously, we showed that the intracellular free calcium concentration ([Ca(2+)]i) that seems to trigger OT release can be elevated by β-NAD(+), cADPR, and ADP in mouse oxytocinergic neurons. As these β-NAD(+) metabolites activate warm-sensitive TRPM2 cation channels, when the incubation temperature is increased, the [Ca(2+)]i in hypothalamic neurons is elevated. However, it has not been determined whether OT release is facilitated by heat in vitro or hyperthermia in vivo in combination with cADPR. Furthermore, it has not been examined whether CD38 and TRPM2 exert their functions on OT release during stress or stress-induced hyperthermia in relation to the anxiolytic roles and social behaviors of OT under stress conditions. Here, we report that OT release from the isolated hypothalami of male mice in culture was enhanced by extracellular application of cADPR or increasing the incubation temperature from 35°C to 38.5°C, and simultaneous stimulation showed a greater effect. This release was inhibited by a cADPR-dependent ryanodine receptor inhibitor and a nonspecific TRPM2 inhibitor. The facilitated release by heat and cADPR was suppressed in the hypothalamus isolated from CD38 knockout mice and CD38- or TRPM2-knockdown mice. In the course of these experiments, we noted that OT release differed markedly between individual mice under stress with group housing. That is, when male mice received cage-switch stress and eliminated due to their social subclass, significantly higher levels of OT release were found in subordinates compared with ordinates. In mice exposed to anxiety stress in an open field, the cerebrospinal fluid (CSF) OT level increased transiently at 5 min after exposure, and the rectal temperature also increased from 36.6°C to 37.8°C. OT levels in the CSF of mice with lipopolysaccharide-induced fever (+0.8°C) were higher than

  4. Arabidopsis HIT4, a regulator involved in heat-triggered reorganization of chromatin and release of transcriptional gene silencing, relocates from chromocenters to the nucleolus in response to heat stress.

    PubMed

    Wang, Lian-Chin; Wu, Jia-Rong; Hsu, Yi-Ju; Wu, Shaw-Jye

    2015-01-01

    Arabidopsis HIT4 is known to mediate heat-induced decondensation of chromocenters and release from transcriptional gene silencing (TGS) with no change in the level of DNA methylation. It is unclear whether HIT4 and MOM1, a well-known DNA methylation-independent transcriptional silencer, have overlapping regulatory functions. A hit4-1/mom1 double mutant strain was generated. Its nuclear morphology and TGS state were compared with those of wild-type, hit4-1, and mom1 plants. Fluorescent protein tagging was employed to track the fates of HIT4, hit4-1 and MOM1 in vivo under heat stress. HIT4- and MOM1-mediated TGS were distinguishable. Both HIT4 and MOM1 were localized normally to chromocenters. Under heat stress, HIT4 relocated to the nucleolus, whereas MOM1 dispersed with the chromocenters. hit4-1 was able to relocate to the nucleolus under heat stress, but its relocation was insufficient to trigger the decompaction of chromocenters. The hypersensitivity to heat associated with the impaired reactivation of TGS in hit4-1 was not alleviated by mom1-induced release from TGS. HIT4 delineates a novel and MOM1-independent TGS regulation pathway. The involvement of a currently unidentified component that links HIT4 relocation and the large-scale reorganization of chromatin, and which is essential for heat tolerance in plants is hypothesized.

  5. Advancement of Latent Trait Theory.

    DTIC Science & Technology

    1988-02-01

    latent trait theory further, and include more varieties of situations. I [51 Investigation of ways of bridging across mathematical psychology and...five years on various topics in Latent Trait Theory, including more general topics such as the method of moments as the least squares solution for...response theory." The address described as (3) in the above list was a one hour special lecture overviewing latent trait models. There were more than two

  6. Effect of radiative transfer of heat released from combustion reaction on temperature distribution: A numerical study for a 2-D system

    NASA Astrophysics Data System (ADS)

    Zhou, Huai-Chun; Ai, Yu-Hua

    2006-09-01

    Both light and heat are produced during a chemical reaction in a combustion process, but traditionally all the energy released is taken as to be transformed into the internal energy of the combustion medium. So the temperature of the medium increases, and then the thermal radiation emitted from it increases too. Chemiluminescence is generated during a chemical reaction and independent of the temperature, and has been used widely for combustion diagnostics. It was assumed in this paper that the total energy released in a combustion reaction is divided into two parts, one part is a self-absorbed heat, and the other is a directly emitted heat. The former is absorbed immediately by the products, becomes the internal energy and then increases the temperature of the products as treated in the traditional way. The latter is emitted directly as radiation into the combustion domain and should be included in the radiation transfer equation (RTE) as a part of radiation source. For a simple, 2-D, gray, emitting absorbing, rectangular system, the numerical study showed that the temperatures in reaction zones depended on the fraction of the directly emitted energy, and the smaller the gas absorption coefficient was, the more strong the dependence appeared. Because the effect of the fraction of the directly emitted heat on the temperature distribution in the reacting zones for gas combustion is significant, it is required to conduct experimental measurements to determine the fraction of self-absorbed heat for different combustion processes.

  7. Learning multimodal latent attributes.

    PubMed

    Fu, Yanwei; Hospedales, Timothy M; Xiang, Tao; Gong, Shaogang

    2014-02-01

    The rapid development of social media sharing has created a huge demand for automatic media classification and annotation techniques. Attribute learning has emerged as a promising paradigm for bridging the semantic gap and addressing data sparsity via transferring attribute knowledge in object recognition and relatively simple action classification. In this paper, we address the task of attribute learning for understanding multimedia data with sparse and incomplete labels. In particular, we focus on videos of social group activities, which are particularly challenging and topical examples of this task because of their multimodal content and complex and unstructured nature relative to the density of annotations. To solve this problem, we 1) introduce a concept of semilatent attribute space, expressing user-defined and latent attributes in a unified framework, and 2) propose a novel scalable probabilistic topic model for learning multimodal semilatent attributes, which dramatically reduces requirements for an exhaustive accurate attribute ontology and expensive annotation effort. We show that our framework is able to exploit latent attributes to outperform contemporary approaches for addressing a variety of realistic multimedia sparse data learning tasks including: multitask learning, learning with label noise, N-shot transfer learning, and importantly zero-shot learning.

  8. A Latent Transition Model with Logistic Regression

    ERIC Educational Resources Information Center

    Chung, Hwan; Walls, Theodore A.; Park, Yousung

    2007-01-01

    Latent transition models increasingly include covariates that predict prevalence of latent classes at a given time or transition rates among classes over time. In many situations, the covariate of interest may be latent. This paper describes an approach for handling both manifest and latent covariates in a latent transition model. A Bayesian…

  9. Impact of Trench and Ramp Film Cooling Designs to Reduce Heat Release Effects in a Reacting Flow

    DTIC Science & Technology

    2012-03-22

    specific heats α angle of inclination τ characteristic time scale µ absolute viscosity σ standard deviation aw adiabatic wall Subscript c...engine’s hot sections located near the combustor. The heat generated by the combustion process is stored in the reacting gas and transfers to the...the combustion process . However, increasing equivalence ratio increases the heat load to the surrounding components and the probability of unburned

  10. A Magnetically Responsive Polydiacetylene Precursor for Latent Fingerprint Analysis.

    PubMed

    Lee, Joosub; Lee, Chan Woo; Kim, Jong-Man

    2016-03-09

    A magnetically responsive diacetylene (DA) powder was developed for the visualization of latent fingerprints. A mixture of the DA and magnetite nanoparticles, applied to a surface containing latent fingermarks, becomes immobilized along the ridge patterns of the fingerprints when a magnetic field is applied. Alignment along the ridge structures is a consequence of favorable hydrophobic interactions occurring between the long alkyl chains in the DAs and the lipid-rich, sebaceous latent fingermarks. UV irradiation of the DA-magnetite composite immobilized on the latent fingerprint results in the generation of blue-colored PDAs. Heat treatment of the blue-colored image promotes a blue-to-red transition as well as fluorescence turn-on. A combination of the aligned pale brown-colored monomeric state, UV irradiation generated blue-colored PDA state, as well as the heat treatment generated red-colored and fluorescent PDA state enables efficient visual imaging of a latent fingerprint, which is deposited on various colored solid surfaces.

  11. Predicting Latent Class Scores for Subsequent Analysis

    ERIC Educational Resources Information Center

    Petersen, Janne; Bandeen-Roche, Karen; Budtz-Jorgensen, Esben; Larsen, Klaus Groes

    2012-01-01

    Latent class regression models relate covariates and latent constructs such as psychiatric disorders. Though full maximum likelihood estimation is available, estimation is often in three steps: (i) a latent class model is fitted without covariates; (ii) latent class scores are predicted; and (iii) the scores are regressed on covariates. We propose…

  12. A solar-thermal energy harvesting scheme: enhanced heat capacity of molten HITEC salt mixed with Sn/SiO(x) core-shell nanoparticles.

    PubMed

    Lai, Chih-Chung; Chang, Wen-Chih; Hu, Wen-Liang; Wang, Zhiming M; Lu, Ming-Chang; Chueh, Yu-Lun

    2014-05-07

    We demonstrated enhanced solar-thermal storage by releasing the latent heat of Sn/SiO(x) core-shell nanoparticles (NPs) embedded in a eutectic salt. The microstructures and chemical compositions of Sn/SiO(x) core-shell NPs were characterized. In situ heating XRD provides dynamic crystalline information about the Sn/SiO(x) core-shell NPs during cyclic heating processes. The latent heat of ∼29 J g(-1) for Sn/SiO(x) core-shell NPs was measured, and 30% enhanced heat capacity was achieved from 1.57 to 2.03 J g(-1) K(-1) for the HITEC solar salt without and with, respectively, a mixture of 5% Sn/SiO(x) core-shell NPs. In addition, an endurance cycle test was performed to prove a stable operation in practical applications. The approach provides a method to enhance energy storage in solar-thermal power plants.

  13. Diabatic heating fields and the generation of available potential energy during FGGE

    NASA Technical Reports Server (NTRS)

    Salstein, David A.; Rosen, Richard D.; Baker, Wayman E.; Kalnay, Eugenia

    1986-01-01

    Global diabatic heating is estimated using fields of directly computed heating components, in particular those due to shortwave radiation, longwave radiation, sensible heating, and latent heating produced every 6 hours. The role of average fields of diabatic heating in the generation of available potential energy is examined. It is observed that latent heating is most significant in generating available potential energy.

  14. Bacterial lipopolysaccharide augments febrile-range hyperthermia-induced heat shock protein 70 expression and extracellular release in human THP1 cells.

    PubMed

    Tulapurkar, Mohan E; Ramarathnam, Aparna; Hasday, Jeffrey D; Singh, Ishwar S

    2015-01-01

    Sepsis, a devastating and often lethal complication of severe infection, is characterized by fever and dysregulated inflammation. While infections activate the inflammatory response in part through Toll-like receptors (TLRs), fever can partially activate the heat shock response with generation of heat shock proteins (HSPs). Since extracellular HSPs, especially HSP70 (eHSP70), are proinflammatory TLR agonists, we investigated how exposure to the TLR4 agonist, bacterial lipopolysaccharide (LPS) and febrile range hyperthermia (FRH; 39.5°C) modify HSP70 expression and extracellular release. Using differentiated THP1 cells, we found that concurrent exposure to FRH and LPS as well as TLR2 and TLR3 agonists synergized to activate expression of inducible HSP72 (HSPA1A) mRNA and protein via a p38 MAP kinase-requiring mechanism. Treatment with LPS for 6 h stimulated eHSP70 release; levels of eHSP70 released at 39.5°C were higher than at 37°C roughly paralleling the increase in intracellular HSP72 in the 39.5°C cells. By contrast, 6 h exposure to FRH in the absence of LPS failed to promote eHSP70 release. Release of eHSP70 by LPS-treated THP1 cells was inhibited by glibenclamide, but not brefeldin, indicating that eHSP70 secretion occurred via a non-classical protein secretory mechanism. Analysis of eHSP70 levels in exosomes and exosome-depleted culture supernatants from LPS-treated THP1 cells using ELISA demonstrated similar eHSP70 levels in unfractionated and exosome-depleted culture supernatants, indicating that LPS-stimulated eHSP70 release did not occur via the exosome pathway. Immunoblot analysis of the exosome fraction of culture supernatants from these cells showed constitutive HSC70 (HSPA8) to be the predominant HSP70 family member present in exosomes. In summary, we have shown that LPS stimulates macrophages to secrete inducible HSP72 via a non-classical non-exosomal pathway while synergizing with FRH exposure to increase both intracellular and secreted levels

  15. Epigenotypes of latent herpesvirus genomes.

    PubMed

    Minarovits, J

    2006-01-01

    Epigenotypes are modified cellular or viral genotypes which differ in transcriptional activity in spite of having an identical (or nearly identical) DNA sequence. Restricted expression of latent, episomal herpesvirus genomes is also due to epigenetic modifications. There is no virus production (lytic viral replication, associated with the expression of all viral genes) in tight latency. In vitro experiments demonstrated that DNA methylation could influence the activity of latent (and/or crucial lytic) promoters of prototype strains belonging to the three herpesvirus subfamilies (alpha-, beta-, and gamma-herpesviruses). In vivo, however, DNA methylation is not a major regulator of herpes simplex virus type 1 (HSV-1, a human alpha-herpesvirus) latent gene expression in neurons of infected mice. In these cells, the promoter/enhancer region of latency-associated transcripts (LATs) is enriched with acetyl histone H3, suggesting that histone modifications may control HSV-1 latency in terminally differentiated, quiescent neurons. Epstein-Barr virus (EBV, a human gamma-herpesvirus) is associated with a series of neoplasms. Latent, episomal EBV genomes are subject to host cell-dependent epigenetic modifications (DNA methylation, binding of proteins and protein complexes, histone modifications). The distinct viral epigenotypes are associated with distinct EBV latency types, i.e., cell type-specific usage of latent EBV promoters controlling the expression of latent, growth transformation-associated EBV genes. The contribution of major epigenetic mechanisms to the regulation of latent EBV promoters is variable. DNA methylation contributes to silencing of Wp and Cp (alternative promoters for transcripts coding for the nuclear antigens EBNA 1-6) and LMP1p, LMP2Ap, and LMP2Bp (promoters for transcripts encoding transmembrane proteins). DNA methylation does not control, however, Qp (a promoter for EBNA1 transcripts only) in lymphoblastoid cell lines (LCLs), although in vitro

  16. Simulation of surface heat fluxes of Typhoon Songda (Chedeng) 2011 using WRF-ARW model

    NASA Astrophysics Data System (ADS)

    Muhammad; Lestari, R. I.; Mulia, F.; Ilhamsyah, Y.; Jalil, Z.; Rizwan

    2017-02-01

    Heat fluxes particularly latent heat is important to drive the development, formation, and intensification of Typhoon Songda (Chedeng). The research was carried out by performing WRF ARW. Three domains with finest resolution at 3.2-km in domain three were utilized in the model. The model involved significant physics parameters, e.g., Kain-Fritsch in the cumulus scheme, Yonsei university in the PBL scheme, and WRF Single-Moment 3-class in the microphysics scheme . The analysis focused on May 26th upon mature stage of Songda (Chedeng). The result showed that the simulation of the eye, three-dimensional structure of internal wind flow, and surface heat fluxes were well-performed. The intensity of Songda (Chedeng) was represented by azimuthal velocity. It showed that the maximum wind was 72 ms-1 occurred at the eye wall at critical radius of 20-km from the eye center where large portion of latent heat available in the area. Significant variation of surface sensible and latent heat fluxes were occurred between the inner and outer core. Thus, it affected to develop a strong horizontal temperature gradient which further intensify the cyclonic inward penetration into the inner core. In terms of disaster risk reduction, this study bring benefit to assist operational weather forecaster to produce good short-range forecasts of the Typhoon intensities. If the surface heat fluxes increase gradually, early warning system on typhoon intensities that will affect over particular region is then released.

  17. The ongoing challenge of latent tuberculosis

    PubMed Central

    Esmail, H.; Barry, C. E.; Young, D. B.; Wilkinson, R. J.

    2014-01-01

    The global health community has set itself the task of eliminating tuberculosis (TB) as a public health problem by 2050. Although progress has been made in global TB control, the current decline in incidence of 2% yr−1 is far from the rate needed to achieve this. If we are to succeed in this endeavour, new strategies to reduce the reservoir of latently infected persons (from which new cases arise) would be advantageous. However, ascertainment of the extent and risk posed by this group is poor. The current diagnostics tests (tuberculin skin test and interferon-gamma release assays) poorly predict who will develop active disease and the therapeutic options available are not optimal for the scale of the intervention that may be required. In this article, we outline a basis for our current understanding of latent TB and highlight areas where innovation leading to development of novel diagnostic tests, drug regimens and vaccines may assist progress. We argue that the pool of individuals at high risk of progression may be significantly smaller than the 2.33 billion thought to be immune sensitized by Mycobacterium tuberculosis and that identifying and targeting this group will be an important strategy in the road to elimination. PMID:24821923

  18. Latent TGF-[beta] structure and activation

    SciTech Connect

    Shi, Minlong; Zhu, Jianghai; Wang, Rui; Chen, Xing; Mi, Lizhi; Walz, Thomas; Springer, Timothy A.

    2011-09-16

    Transforming growth factor (TGF)-{beta} is stored in the extracellular matrix as a latent complex with its prodomain. Activation of TGF-{beta}1 requires the binding of {alpha}v integrin to an RGD sequence in the prodomain and exertion of force on this domain, which is held in the extracellular matrix by latent TGF-{beta} binding proteins. Crystals of dimeric porcine proTGF-{beta}1 reveal a ring-shaped complex, a novel fold for the prodomain, and show how the prodomain shields the growth factor from recognition by receptors and alters its conformation. Complex formation between {alpha}v{beta}6 integrin and the prodomain is insufficient for TGF-{beta}1 release. Force-dependent activation requires unfastening of a 'straitjacket' that encircles each growth-factor monomer at a position that can be locked by a disulphide bond. Sequences of all 33 TGF-{beta} family members indicate a similar prodomain fold. The structure provides insights into the regulation of a family of growth and differentiation factors of fundamental importance in morphogenesis and homeostasis.

  19. Latent geometry of bipartite networks

    NASA Astrophysics Data System (ADS)

    Kitsak, Maksim; Papadopoulos, Fragkiskos; Krioukov, Dmitri

    2017-03-01

    Despite the abundance of bipartite networked systems, their organizing principles are less studied compared to unipartite networks. Bipartite networks are often analyzed after projecting them onto one of the two sets of nodes. As a result of the projection, nodes of the same set are linked together if they have at least one neighbor in common in the bipartite network. Even though these projections allow one to study bipartite networks using tools developed for unipartite networks, one-mode projections lead to significant loss of information and artificial inflation of the projected network with fully connected subgraphs. Here we pursue a different approach for analyzing bipartite systems that is based on the observation that such systems have a latent metric structure: network nodes are points in a latent metric space, while connections are more likely to form between nodes separated by shorter distances. This approach has been developed for unipartite networks, and relatively little is known about its applicability to bipartite systems. Here, we fully analyze a simple latent-geometric model of bipartite networks and show that this model explains the peculiar structural properties of many real bipartite systems, including the distributions of common neighbors and bipartite clustering. We also analyze the geometric information loss in one-mode projections in this model and propose an efficient method to infer the latent pairwise distances between nodes. Uncovering the latent geometry underlying real bipartite networks can find applications in diverse domains, ranging from constructing efficient recommender systems to understanding cell metabolism.

  20. Roles of Clathrate Hydrates in Crustal Heating and Volatile Storage/Release on Earth, Mars, and Beyond

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.; Beget, J.; Furfaro, R.; Prieto-Ballesteros, O.; Palmero-Rodriguez, J. A.

    2007-12-01

    Clathrate hydrates are stable through much of the Solar System. These materials and hydrate-like amorphous associations of water with N2, CO, CH4, CO2, O2 and other molecules could, in fact, constitute the bulk of the non-rock components of some icy satellites, comets, and Kuiper Belt Objects. CO2 clathrate is thermodynamically stable at the Martian South Pole surface and could form a significant fraction of both Martian polar caps and icy permafrost distributed across one-third of the Martian surface. CH4 clathrate is the largest clathrate material in Earth's permafrost and cold seafloor regions, and it may be a major volatile reservoir on Mars, too. CO2 clathrate is less abundant on Earth but it might store most of Mars' CO2 inventory and thus may be one of the critical components in the climate system of that planet, just as CH4 clathrate is for Earth. These ice-like phases not only store biologically, geologically, and climatologically important gases, but they also are natural thermal insulators. Thus, they retard the conductive flow of geothermal heat, and thick accumulations of them can modify geotherms, cause brines to exist where otherwise they would not, and induce low-grade metamorphism of upper crustal rocks underlying the insulating bodies. This mechanism of crustal heating may be especially important in assisting hydrogeologic activity on Mars, gas-rich carbonaceous asteroids, icy satellites, and Kuiper Belt Objects. These worlds, compared to Earth, are comparatively energy starved and frozen but may partly make up for their deficit of joules by having large accumulations of joule-conserving hydrates. Thick, continuous layers of clathrate may seal in gases and produce high gas fugacities in aquifers underlying the clathrates, thus producing gas-rich reservoirs capable of erupting violently. This may have happened repeatedly in Earth history, with global climatic consequences for abrupt climate change. We have hypothesized that such eruptions may have

  1. Efficient Heat Storage Materials: Metallic Composites Phase-Change Materials for High-Temperature Thermal Energy Storage

    SciTech Connect

    2011-11-21

    HEATS Project: MIT is developing efficient heat storage materials for use in solar and nuclear power plants. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun’s not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. MIT is designing nanostructured heat storage materials that can store a large amount of heat per unit mass and volume. To do this, MIT is using phase change materials, which absorb a large amount of latent heat to melt from solid to liquid. MIT’s heat storage materials are designed to melt at high temperatures and conduct heat well—this makes them efficient at storing and releasing heat and enhances the overall efficiency of the thermal storage and energy-generation process. MIT’s low-cost heat storage materials also have a long life cycle, which further enhances their efficiency.

  2. A DIRECT MEASUREMENT OF THE HEAT RELEASE IN THE OUTER CRUST OF THE TRANSIENTLY ACCRETING NEUTRON STAR XTE J1709-267

    SciTech Connect

    Degenaar, N.; Miller, J. M.; Wijnands, R.

    2013-04-20

    The heating and cooling of transiently accreting neutron stars provides a powerful probe of the structure and composition of their crust. Observations of superbursts and cooling of accretion-heated neutron stars require more heat release than is accounted for in current models. Obtaining firm constraints on the depth and magnitude of this extra heat is challenging and therefore its origin remains uncertain. We report on Swift and XMM-Newton observations of the transient neutron star low-mass X-ray binary XTE J1709-267, which were made in 2012 September-October when it transitioned to quiescence after a {approx_equal}10 week long accretion outburst. The source is detected with XMM-Newton at a 0.5-10 keV luminosity of L{sub X} {approx_equal} 2 Multiplication-Sign 10{sup 34}(D/8.5 kpc){sup 2} erg s{sup -1}. The X-ray spectrum consists of a thermal component that fits to a neutron star atmosphere model and a non-thermal emission tail, each of which contribute {approx_equal}50% to the total flux. The neutron star temperature decreases from {approx_equal}158 to {approx_equal}152 eV during the {approx_equal}8 hr long observation. This can be interpreted as cooling of a crustal layer located at a column density of y {approx_equal} 5 Multiplication-Sign 10{sup 12} g cm{sup -2} ({approx_equal}50 m inside the neutron star), which is just below the ignition depth of superbursts. The required heat generation in the layers on top would be {approx_equal}0.06-0.13 MeV per accreted nucleon. The magnitude and depth rule out electron captures and nuclear fusion reactions as the heat source, but it may be accounted for by chemical separation of light and heavy nuclei. Low-level accretion offers an alternative explanation for the observed variability.

  3. Heat transfer mechanisms in bubbly Rayleigh-Bénard convection.

    PubMed

    Oresta, Paolo; Verzicco, Roberto; Lohse, Detlef; Prosperetti, Andrea

    2009-08-01

    The heat transfer mechanism in Rayleigh-Bénard convection in a liquid with a mean temperature close to its boiling point is studied through numerical simulations with pointlike vapor bubbles, which are allowed to grow or shrink through evaporation and condensation and which act back on the flow both thermally and mechanically. It is shown that the effect of the bubbles is strongly dependent on the ratio of the sensible heat to the latent heat as embodied in the Jakob number Ja. For very small Ja the bubbles stabilize the flow by absorbing heat in the warmer regions and releasing it in the colder regions. With an increase in Ja, the added buoyancy due to the bubble growth destabilizes the flow with respect to single-phase convection and considerably increases the Nusselt number.

  4. Indexing by Latent Semantic Analysis.

    ERIC Educational Resources Information Center

    Deerwester, Scott; And Others

    1990-01-01

    Describes a new method for automatic indexing and retrieval called latent semantic indexing (LSI). Problems with matching query words with document words in term-based information retrieval systems are discussed, semantic structure is examined, singular value decomposition (SVD) is explained, and the mathematics underlying the SVD model is…

  5. Estimation in Latent Trait Models.

    ERIC Educational Resources Information Center

    Rigdon, Steven E.; Tsutakawa, Robert K.

    Estimation of ability and item parameters in latent trait models is discussed. When both ability and item parameters are considered fixed but unknown, the method of maximum likelihood for the logistic or probit models is well known. Discussed are techniques for estimating ability and item parameters when the ability parameters or item parameters…

  6. Euphorbia Kansui Reactivates Latent HIV

    PubMed Central

    Cary, Daniele C.; Fujinaga, Koh; Peterlin, B. Matija

    2016-01-01

    While highly active anti-retroviral therapy has greatly improved the lives of HIV infected individuals, these treatments are unable to eradicate the virus. Current approaches to reactivate the virus have been limited by toxicity, lack of an orally available therapy, and limited responses in primary CD4+ T cells and in clinical trials. The PKC agonist ingenol, purified from Euphorbia plants, is a potent T cell activator and reactivates latent HIV. Euphorbia kansui itself has been used for centuries in traditional Chinese medicine to treat ascites, fluid retention, and cancer. We demonstrate that an extract of this plant, Euphorbia kansui, is capable of recapitulating T cell activation induced by the purified ingenol. Indeed, Euphorbia kansui induced expression of the early T cell activation marker CD69 and P-TEFb in a dose-dependent manner. Furthermore, Euphorbia kansui reactivated latent HIV in a CD4+ T cell model of latency and in HIV+ HAART suppressed PBMC. When combined with the other latency reversing agents, the effective dose of Euphorbia kansui required to reactive HIV was reduced 10-fold and resulted in synergistic reactivation of latent HIV. We conclude that Euphorbia Euphorbia kansui reactivates latent HIV and activates CD4+ T cells. When used in combination with a latency reversing agent, the effective dose of Euphorbia kansui is reduced; which suggests its application as a combination strategy to reactivate latent HIV while limiting the toxicity due to global T cell activation. As a natural product, which has been used in traditional medicine for thousands of years, Euphorbia kansui is attractive as a potential treatment strategy, particularly in resource poor countries with limited treatment options. Further clinical testing will be required to determine its safety with current anti-retroviral therapies. PMID:27977742

  7. Nonstationary Heat Conduction in Atomic Systems

    NASA Astrophysics Data System (ADS)

    Singh, Amit K.

    Understanding heat at the atomistic level is an interesting exercises. It is fascinating to note how the vibration of atoms result into thermodynamic concept of heat. This thesis aims to bring insights into different constitutive laws of heat conduction. We also develop a framework in which the interaction of thermostats to the system can be studied and a well known Kapitza effect can be reduced. The thesis also explores stochastic and continuum methods to model the latent heat release in the first order transition of ideal silicon surfaces into dimers. We divide the thesis into three works which are connected to each other: 1. Fourier's law leads to a diffusive model of heat transfer in which a thermal signal propagates infinitely fast and the only material parameter is the thermal conductivity. In micro- and nano-scale systems, non-Fourier effects involving coupled diffusion and wavelike propagation of heat can become important. An extension of Fourier's law to account for such effects leads to a Jeffreys-type model for heat transfer with two relaxation times. In this thesis, we first propose a new Thermal Parameter Identification (TPI) method for obtaining the Jeffreys-type thermal parameters from molecular dynamics simulations. The TPI method makes use of a nonlinear regression-based approach for obtaining the coefficients in analytical expressions for cosine and sine-weighted averages of temperature and heat flux over the length of the system. The method is applied to argon nanobeams over a range of temperature and system sizes. The results for thermal conductivity are found to be in good agreement with standard Green-Kubo and direct method calculations. The TPI method is more efficient for systems with high diffusivity and has the advantage, that unlike the direct method, it is free from the influence of thermostats. In addition, the method provides the thermal relaxation times for argon. Using the determined parameters, the Jeffreys-type model is able to

  8. A Latent Class Model for Rating Data.

    ERIC Educational Resources Information Center

    Rost, Jurgen

    1985-01-01

    A latent class model for rating data is presented which provides an alternative to the latent trait approach of analyzing test data. It is the analog of Andrich's binomial Rasch model for Lazarsfeld's latent class analysis (LCA). Response probabilities for rating categories follow a binomial distribution and depend on class-specific item…

  9. Latent Growth Modeling for Logistic Response Functions

    ERIC Educational Resources Information Center

    Choi, Jaehwa; Harring, Jeffrey R.; Hancock, Gregory R.

    2009-01-01

    Throughout much of the social and behavioral sciences, latent growth modeling (latent curve analysis) has become an important tool for understanding individuals' longitudinal change. Although nonlinear variations of latent growth models appear in the methodological and applied literature, a notable exclusion is the treatment of growth following…

  10. Quarterly technical progress report No. 2, December 20-March 19, 1982. Second quarterly report on the effect of rapid heating rate on coal nitrogen and sulfur release

    SciTech Connect

    Gat, N.

    1982-04-26

    A laser pyrolysis technique is applied to the investigation of the effects of heating rate on release of coal-bound sulfur and nitrogen. An experimental system characterization and calibration has been completed. A detailed documentation was prepared describing the 3-color pyrometer and the data analysis technique. The coal particle feed system has been calibrated to provide accurate mass flow rate at pre-selected particle velocities. The first batch of samples submitted for chemical analysis will be used for the determination of kinetics parameters at a high heating rate (approximately equal to 10/sup 6/ K/s). The coal used presently is a Montana Rosebud. Two other coals are available; one is ILL No. 6 (through EERC) which will need to be pulverized and the second is a Pitt. hv-A (through KVB). It was confirmed that sieve and drag size distribution of coal differ significantly, and that particle shape effects may be significant in the modelling of particle dynamics.

  11. Aerodynamic Heating Computations for Projectiles. Volume 1. In-Depth Heat Conduction Modifications to the ABRES Shape Change Code (BRLASCC)

    DTIC Science & Technology

    1984-06-01

    Modifications .............................. 16 2.2.2 Explicit Grid Modifications .............................. 19 2.3 Latent Heat of Fusion ...equations are utilized more accurately The user may now input latent heat of fusion for melting materials and BRLASCC will account for this energy during...contact resistance to the finite-difference conduction equations, (3) improved in-depth modeling by inclusion of latent heat of fusion , (4) increased

  12. Mapping regional distribution of land surface heat fluxes on the southern side of the central Himalayas using TESEBS

    NASA Astrophysics Data System (ADS)

    Amatya, Pukar Man; Ma, Yaoming; Han, Cunbo; Wang, Binbin; Devkota, Lochan Prasad

    2016-05-01

    Recent scientific studies based on large-scale climate model have highlighted the importance of the heat release from the southern side of the Himalayas for the development of South Asian Summer Monsoon. However, studies related to land surface heat fluxes are nonexistent on the southern side. In this study, we test the feasibility of deriving land surface heat fluxes on the central Himalayan region using Topographically Enhanced Surface Energy Balance System (TESEBS), which is forced by MODIS land surface products and Global Land Data Assimilation System (GLDAS) meteorological data. The model results were validated using the first eddy covariance measurement system established in the southern side of the central Himalayas. The derived land surface heat fluxes were close to the field measurements with mean bias of 15.97, -19.89, 8.79, and -20.39 W m-2 for net radiation flux, ground heat flux, sensible heat flux, and latent heat flux respectively. Land surface heat fluxes show strong contrast in pre monsoon, summer monsoon, post monsoon, and winter seasons and different land surface states among the different physiographic regions. In the central Himalayas, the latent heat flux is the dominant consumer of available energy for all physiographic regions except for the High Himalaya where the sensible heat flux is high.

  13. Latent period in clinical radiation myelopathy

    SciTech Connect

    Schultheiss, T.E.; Higgins, E.M.; El-Mahdi, A.M.

    1984-07-01

    Seventy-seven papers containing data on more than 300 cases of radiation myelopathy have been analyzed. The data suggest that the latent periods are similar in the cervical and thoracic levels of the spinal cord and are bimodally distributed. Myelopathy of lumbar cord apparently has a shorter latent period. As in controlled animal experiments, the latent period decreases with increasing dose. Furthermore, the variation in latent periods also decreases with dose. It is also seen that retreated patients and pediatric or adolescent patients have greatly reduced latent periods. The implications of these findings as they compare with the animal data are discussed.

  14. Enceladus' Enigmatic Heat Flow

    NASA Astrophysics Data System (ADS)

    Howett, C.; Spencer, J. R.; Spencer, D.; Verbiscer, A.; Hurford, T.; Segura, M.

    2013-12-01

    Accurate knowledge of Enceladus' heat flow is important because it provides a vital constraint on Enceladus' tidal dissipation mechanisms, orbital evolution, and the physical processes that generate the plumes. In 2011 we published an estimate of the current heat flow from Enceladus' active south polar terrain: 15.8 +/- 3.1 GW (Howett et al., 2011). This value was calculated by first estimating by modeling, and then removing, the passive component from 17 to 1000 micron observations made of the entire south polar terrain by Cassini's Composite Infrared Spectrometer (CIRS). The heat flow was then directly calculated from the residual, assumed endogenic, component. The derived heat flow of 15.8 GW was surprisingly high, about 10 times greater than that predicted by steady-state tidal heating (Meyer and Wisdom, 2007). CIRS has also returned high spatial resolution observations of Enceladus' active south polar terrain. Two separate observations are used: 9 to 16 micron observations taken over nearly the complete south polar terrain and a single 17 to 1000 micron scan over Damascus, Baghdad and Cairo. The shorter wavelength observations are only sensitive to high temperature emission (>70 K), and so longer wavelength observations are required (despite their limited spatial coverage) to estimate the low temperature emission from the stripes. Analysis of these higher resolution observations tells a different story of Enceladus' endogenic heat flow: the preliminary estimate of the heat flow from the active tiger stripes using these observations is 4.2 GW. An additional 0.5 GW must be added to this number to account for the latent heat release by the plumes (Ingersoll and Pankine 2009), giving a total preliminary estimate of 4.9 GW. The discrepancy in these two numbers is significant and we are currently investigating the cause. One possible reason is that there is significantly higher endogenic emission from the regions between the tiger stripes than we currently estimate

  15. Tuberculosis Infection and Latent Tuberculosis

    PubMed Central

    2016-01-01

    Active tuberculosis (TB) has a greater burden of TB bacilli than latent TB and acts as an infection source for contacts. Latent tuberculosis infection (LTBI) is the state in which humans are infected with Mycobacterium tuberculosis without any clinical symptoms, radiological abnormality, or microbiological evidence. TB is transmissible by respiratory droplet nucleus of 1–5 µm in diameter, containing 1–10 TB bacilli. TB transmission is affected by the strength of the infectious source, infectiousness of TB bacilli, immunoresistance of the host, environmental stresses, and biosocial factors. Infection controls to reduce TB transmission consist of managerial activities, administrative control, engineering control, environmental control, and personal protective equipment provision. However, diagnosis and treatment for LTBI as a national TB control program is an important strategy on the precondition that active TB is not missed. Therefore, more concrete evidences for LTBI management based on clinical and public perspectives are needed. PMID:27790271

  16. Control of heat transfer in continuous-feeding Czochralski-silicon crystal growth with a water-cooled jacket

    NASA Astrophysics Data System (ADS)

    Zhao, Wenhan; Liu, Lijun

    2017-01-01

    The continuous-feeding Czochralski method is an effective method to reduce the cost of single crystal silicon. By promoting the crystal growth rate, the cost can be reduced further. However, more latent heat will be released at the melt-crystal interface under a high crystal growth rate. In this study, a water-cooled jacket was applied to enhance the heat transfer at the melt-crystal interface. Quasi-steady-state numerical calculation was employed to investigate the impact of the water-cooled jacket on the heat transfer at the melt-crystal interface. Latent heat released during the crystal growth process at the melt-crystal interface and absorbed during feedstock melting at the feeding zone was modeled in the simulations. The results show that, by using the water-cooled jacket, heat transfer in the growing crystal is enhanced significantly. Melt-crystal interface deflection and thermal stress increase simultaneously due to the increase of radial temperature at the melt-crystal interface. With a modified heat shield design, heat transfer at the melt-crystal interface is well controlled. The crystal growth rate can be increased by 20%.

  17. Anticancer drugs cause release of exosomes with heat shock proteins from human hepatocellular carcinoma cells that elicit effective natural killer cell antitumor responses in vitro.

    PubMed

    Lv, Li-Hong; Wan, Yun-Le; Lin, Yan; Zhang, Wei; Yang, Mei; Li, Guo-Lin; Lin, Hao-Ming; Shang, Chang-Zhen; Chen, Ya-Jin; Min, Jun

    2012-05-04

    Failure of immune surveillance related to inadequate host antitumor immune responses has been suggested as a possible cause of the high incidence of recurrence and poor overall survival outcome of hepatocellular carcinoma. The stress-induced heat shock proteins (HSPs) are known to act as endogenous "danger signals" that can improve tumor immunogenicity and induce natural killer (NK) cell responses. Exosome is a novel secretory pathway for HSPs. In our experiments, the immune regulatory effect of the HSP-bearing exosomes secreted by human hepatocellular carcinoma cells under stress conditions on NK cells was studied. ELISA results showed that the production of HSP60, HSP70, and HSP90 was up-regulated in both cell lines in a stress-specific manner. After exposure to hepatocellular carcinoma cell-resistant or sensitive anticancer drugs (hereafter referred to as "resistant" or "sensitive" anticancer drug), the membrane microvesicles were actively released by hepatocellular carcinoma cells, differing in their ability to present HSPs on the cell surface, which were characterized as exosomes. Acting as a decoy, the HSP-bearing exosomes efficiently stimulated NK cell cytotoxicity and granzyme B production, up-regulated the expression of inhibitory receptor CD94, and down-regulated the expression of activating receptors CD69, NKG2D, and NKp44. Notably, resistant anticancer drugs enhanced exosome release and generated more exosome-carried HSPs, which augmented the activation of the cytotoxic response. In summary, our findings demonstrated that exosomes derived from resistant anticancer drug-treated HepG2 cells conferred superior immunogenicity in inducing HSP-specific NK cell responses, which provided a clue for finding an efficient vaccine for hepatocellular carcinoma immunotherapy.

  18. The Effect of Ethanol Addition to Gasoline on Low- and Intermediate-Temperature Heat Release under Boosted Conditions in Kinetically Controlled Engines

    NASA Astrophysics Data System (ADS)

    Vuilleumier, David Malcolm

    The detailed study of chemical kinetics in engines has become required to further advance engine efficiency while simultaneously lowering engine emissions. This push for higher efficiency engines is not caused by a lack of oil, but by efforts to reduce anthropogenic carbon dioxide emissions, that cause global warming. To operate in more efficient manners while reducing traditional pollutant emissions, modern internal combustion piston engines are forced to operate in regimes in which combustion is no longer fully transport limited, and instead is at least partially governed by chemical kinetics of combusting mixtures. Kinetically-controlled combustion allows the operation of piston engines at high compression ratios, with partially-premixed dilute charges; these operating conditions simultaneously provide high thermodynamic efficiency and low pollutant formation. The investigations presented in this dissertation study the effect of ethanol addition on the low-temperature chemistry of gasoline type fuels in engines. These investigations are carried out both in a simplified, fundamental engine experiment, named Homogeneous Charge Compression Ignition, as well as in more applied engine systems, named Gasoline Compression Ignition engines and Partial Fuel Stratification engines. These experimental investigations, and the accompanying modeling work, show that ethanol is an effective scavenger of radicals at low temperatures, and this inhibits the low temperature pathways of gasoline oxidation. Further, the investigations measure the sensitivity of gasoline auto-ignition to system pressure at conditions that are relevant to modern engines. It is shown that at pressures above 40 bar and temperatures below 850 Kelvin, gasoline begins to exhibit Low-Temperature Heat Release. However, the addition of 20% ethanol raises the pressure requirement to 60 bar, while the temperature requirement remains unchanged. These findings have major implications for a range of modern engines

  19. The heat source of the foehn revisited

    NASA Astrophysics Data System (ADS)

    Ólafsson, H.; Petersen, G. N.

    2012-04-01

    A large observational data set from Iceland is used to explore the connection between the heat surplus on the downstream side of mountains, upstream precipitation and elements of the atmospheric flow. A typical foehn case is also simulated and used to explore the role of precipitation and latent heat in heating the downstream flow. Some of the key findings are that latent heating appears not to be an important factor for heating the foehn in Iceland and that there is no clear relationship between upstream precipitation and downstream heating. The heating on the downstream side is attributed to descent of potentially warm air and insolation. The case study suggests that the latent heating may have an impact, however not through heating aloft, but through cooling at low levels and enhanced upstream blocking effect.

  20. Toward Surface-Enhanced Raman Imaging of Latent Fingerprints

    SciTech Connect

    Connatser, Raynella M; Prokes, Sharka M.; Glembocki, Orest; Schuler, Rebecca A.; Gardner, Charles W.; Lewis Sr, Samuel Arthur; Lewis, Linda A

    2010-01-01

    Exposure to light or heat, or simply a dearth of fingerprint material, renders some latent fingerprints undetectable using conventional methods. We begin to address such elusive fingerprints using detection targeting photo- and thermally stable fingerprint constituents: surface-enhanced Raman spectroscopy (SERS). SERS can give descriptive vibrational spectra of amino acids, among other robust fingerprint constituents, and good sensitivity can be attained by improving metal-dielectric nanoparticle substrates. With SERS chemical imaging, vibrational bands intensities recreate a visual of fingerprint topography. The impact of nanoparticle synthesis route, dispersal methodology-deposition solvent, and laser wavelength are discussed, as are data from enhanced vibrational spectra of fingerprint components. SERS and Raman chemical images of fingerprints and realistic contaminants are shown. To our knowledge, this represents the first SERS imaging of fingerprints. In conclusion, this work progresses toward the ultimate goal of vibrationally detecting latent prints that would otherwise remain undetected using traditional development methods.

  1. Toward surface-enhanced Raman imaging of latent fingerprints.

    PubMed

    Connatser, R Maggie; Prokes, Sharka M; Glembocki, Orest J; Schuler, Rebecca L; Gardner, Charles W; Lewis, Samuel A; Lewis, Linda A

    2010-11-01

    Exposure to light or heat, or simply a dearth of fingerprint material, renders some latent fingerprints undetectable using conventional methods. We begin to address such elusive fingerprints using detection targeting photo- and thermally stable fingerprint constituents: surface-enhanced Raman spectroscopy (SERS). SERS can give descriptive vibrational spectra of amino acids, among other robust fingerprint constituents, and good sensitivity can be attained by improving metal-dielectric nanoparticle substrates. With SERS chemical imaging, vibrational bands' intensities recreate a visual of fingerprint topography. The impact of nanoparticle synthesis route, dispersal methodology-deposition solvent, and laser wavelength are discussed, as are data from enhanced vibrational spectra of fingerprint components. SERS and Raman chemical images of fingerprints and realistic contaminants are shown. To our knowledge, this represents the first SERS imaging of fingerprints. In conclusion, this work progresses toward the ultimate goal of vibrationally detecting latent prints that would otherwise remain undetected using traditional development methods.

  2. An evaluation of the assumed beta probability density function subgrid-scale model for large eddy simulation of nonpremixed, turbulent combustion with heat release

    SciTech Connect

    Wall, Clifton; Boersma, Bendiks Jan; Moin, Parviz

    2000-10-01

    The assumed beta distribution model for the subgrid-scale probability density function (PDF) of the mixture fraction in large eddy simulation of nonpremixed, turbulent combustion is tested, a priori, for a reacting jet having significant heat release (density ratio of 5). The assumed beta distribution is tested as a model for both the subgrid-scale PDF and the subgrid-scale Favre PDF of the mixture fraction. The beta model is successful in approximating both types of PDF but is slightly more accurate in approximating the normal (non-Favre) PDF. To estimate the subgrid-scale variance of mixture fraction, which is required by the beta model, both a scale similarity model and a dynamic model are used. Predictions using the dynamic model are found to be more accurate. The beta model is used to predict the filtered value of a function chosen to resemble the reaction rate. When no model is used, errors in the predicted value are of the same order as the actual value. The beta model is found to reduce this error by about a factor of two, providing a significant improvement. (c) 2000 American Institute of Physics.

  3. Electric field triggering the spin reorientation and controlling the absorption and release of heat in the induced multiferroic compound EuTiO{sub 3}

    SciTech Connect

    Ranke, P. J. von Ribeiro, P. O.; Alho, B. P.; Alvarenga, T. S. T.; Nobrega, E. P.; Caldas, A.; Sousa, V. S. R. de; Lopes, P. H. O.; Oliveira, N. A. de; Gama, S.; Carvalho, A. Magnus G.

    2015-12-28

    We report remarkable results due to the coupling between the magnetization and the electric field induced polarization in EuTiO{sub 3}. Using a microscopic model Hamiltonian to describe the three coupled sublattices, Eu-(spin-up), Eu-(spin-down), and Ti-(moment), the spin flop and spin reorientation phase transitions were described with and without the electric-magnetic coupling interaction. The external electric field can be used to tune the temperature of the spin reorientation phase transition T{sub SR} = T{sub SR}(E). When the T{sub SR} is tuned around the EuTiO{sub 3}—Néel temperature (T{sub N} = 5.5 K), an outstanding effect emerges in which EuTiO{sub 3} releases heat under magnetic field change. The electric field controlling the spin reorientation transition and the endo-exothermic processes are discussed through the microscopic interactions model parameters.

  4. Bayesian variable selection for latent class models.

    PubMed

    Ghosh, Joyee; Herring, Amy H; Siega-Riz, Anna Maria

    2011-09-01

    In this article, we develop a latent class model with class probabilities that depend on subject-specific covariates. One of our major goals is to identify important predictors of latent classes. We consider methodology that allows estimation of latent classes while allowing for variable selection uncertainty. We propose a Bayesian variable selection approach and implement a stochastic search Gibbs sampler for posterior computation to obtain model-averaged estimates of quantities of interest such as marginal inclusion probabilities of predictors. Our methods are illustrated through simulation studies and application to data on weight gain during pregnancy, where it is of interest to identify important predictors of latent weight gain classes.

  5. Relationships between outgoing longwave radiation and diabatic heating in reanalyses

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Randel, William J.; Fu, Rong

    2016-12-01

    This study investigates relationships between daily variability in National Oceanographic and Atmospheric Administration (NOAA) outgoing longwave radiation (OLR), as a proxy for deep convection, and the global diabatic heat budget derived from reanalysis data sets. Results are evaluated based on data from ECMWF Reanalysis (ERA-Interim), Japanese 55-year Reanalysis (JRA-55) and Modern-Era Retrospective Analysis for Research and Applications (MERRA2). The diabatic heating is separated into components linked to `physics' (mainly latent heat fluxes), plus longwave (LW) and shortwave (SW) radiative tendencies. Transient variability in deep convection is highly correlated with diabatic heating throughout the troposphere and stratosphere. Correlation patterns and composite analyses show that enhanced deep convection (lower OLR) is linked to amplified heating in the tropical troposphere and in the mid-latitude storm tracks, tied to latent heat release. Enhanced convection is also linked to radiative cooling in the lower stratosphere, due to weaker upwelling LW from lower altitudes. Enhanced transient deep convection increases LW and decreases SW radiation in the lower troposphere, with opposite effects in the mid to upper troposphere. The compensating effects in LW and SW radiation are largely linked to variations in cloud fraction and water content (vapor, liquid and ice). These radiative balances in reanalyses are in agreement with idealized calculations using a column radiative transfer model. The overall relationships between OLR and diabatic heating are robust among the different reanalyses, although there are differences in radiative tendencies in the tropics due to large differences of cloud water and ice content among the reanalyses. These calculations provide a simple statistical method to quantify variations in diabatic heating linked to transient deep convection in the climate system.

  6. Estimating and Interpreting Latent Variable Interactions: A Tutorial for Applying the Latent Moderated Structural Equations Method

    ERIC Educational Resources Information Center

    Maslowsky, Julie; Jager, Justin; Hemken, Douglas

    2015-01-01

    Latent variables are common in psychological research. Research questions involving the interaction of two variables are likewise quite common. Methods for estimating and interpreting interactions between latent variables within a structural equation modeling framework have recently become available. The latent moderated structural equations (LMS)…

  7. Optimization-Based Model Fitting for Latent Class and Latent Profile Analyses

    ERIC Educational Resources Information Center

    Huang, Guan-Hua; Wang, Su-Mei; Hsu, Chung-Chu

    2011-01-01

    Statisticians typically estimate the parameters of latent class and latent profile models using the Expectation-Maximization algorithm. This paper proposes an alternative two-stage approach to model fitting. The first stage uses the modified k-means and hierarchical clustering algorithms to identify the latent classes that best satisfy the…

  8. Semi-Nonparametric Methods for Detecting Latent Non-Normality: A Fusion of Latent Trait and Ordered Latent Class Modeling

    ERIC Educational Resources Information Center

    Schmitt, J. Eric; Mehta, Paras D.; Aggen, Steven H.; Kubarych, Thomas S.; Neale, Michael C.

    2006-01-01

    Ordered latent class analysis (OLCA) can be used to approximate unidimensional latent distributions. The main objective of this study is to evaluate the method of OLCA in detecting non-normality of an unobserved continuous variable (i.e., a common factor) used to explain the covariation between dichotomous item-level responses. Using simulation,…

  9. The Latent Structure of Autistic Traits: A Taxometric, Latent Class and Latent Profile Analysis of the Adult Autism Spectrum Quotient

    ERIC Educational Resources Information Center

    James, Richard J.; Dubey, Indu; Smith, Danielle; Ropar, Danielle; Tunney, Richard J.

    2016-01-01

    Autistic traits are widely thought to operate along a continuum. A taxometric analysis of Adult Autism Spectrum Quotient data was conducted to test this assumption, finding little support but identifying a high severity taxon. To understand this further, latent class and latent profile models were estimated that indicated the presence of six…

  10. External stimulation-controllable heat-storage ceramics

    PubMed Central

    Tokoro, Hiroko; Yoshikiyo, Marie; Imoto, Kenta; Namai, Asuka; Nasu, Tomomichi; Nakagawa, Kosuke; Ozaki, Noriaki; Hakoe, Fumiyoshi; Tanaka, Kenji; Chiba, Kouji; Makiura, Rie; Prassides, Kosmas; Ohkoshi, Shin-ichi

    2015-01-01

    Commonly available heat-storage materials cannot usually store the energy for a prolonged period. If a solid material could conserve the accumulated thermal energy, then its heat-storage application potential is considerably widened. Here we report a phase transition material that can conserve the latent heat energy in a wide temperature range, T<530 K and release the heat energy on the application of pressure. This material is stripe-type lambda-trititanium pentoxide, λ-Ti3O5, which exhibits a solid–solid phase transition to beta-trititanium pentoxide, β-Ti3O5. The pressure for conversion is extremely small, only 600 bar (60 MPa) at ambient temperature, and the accumulated heat energy is surprisingly large (230 kJ L−1). Conversely, the pressure-produced beta-trititanium pentoxide transforms to lambda-trititanium pentoxide by heat, light or electric current. That is, the present system exhibits pressure-and-heat, pressure-and-light and pressure-and-current reversible phase transitions. The material may be useful for heat storage, as well as in sensor and switching memory device applications. PMID:25962982

  11. External stimulation-controllable heat-storage ceramics.

    PubMed

    Tokoro, Hiroko; Yoshikiyo, Marie; Imoto, Kenta; Namai, Asuka; Nasu, Tomomichi; Nakagawa, Kosuke; Ozaki, Noriaki; Hakoe, Fumiyoshi; Tanaka, Kenji; Chiba, Kouji; Makiura, Rie; Prassides, Kosmas; Ohkoshi, Shin-ichi

    2015-05-12

    Commonly available heat-storage materials cannot usually store the energy for a prolonged period. If a solid material could conserve the accumulated thermal energy, then its heat-storage application potential is considerably widened. Here we report a phase transition material that can conserve the latent heat energy in a wide temperature range, T<530 K and release the heat energy on the application of pressure. This material is stripe-type lambda-trititanium pentoxide, λ-Ti3O5, which exhibits a solid-solid phase transition to beta-trititanium pentoxide, β-Ti3O5. The pressure for conversion is extremely small, only 600 bar (60 MPa) at ambient temperature, and the accumulated heat energy is surprisingly large (230 kJ L(-1)). Conversely, the pressure-produced beta-trititanium pentoxide transforms to lambda-trititanium pentoxide by heat, light or electric current. That is, the present system exhibits pressure-and-heat, pressure-and-light and pressure-and-current reversible phase transitions. The material may be useful for heat storage, as well as in sensor and switching memory device applications.

  12. Response of the mesoscale atmosphere to diabatic heating

    NASA Technical Reports Server (NTRS)

    Robertson, F. R.

    1985-01-01

    A study was initiated to determine the influence of convective latent heat release/diabatic heating on the production of kinetic energy during AVE/SESAME I. The primary focus has been on the relative importance of thermally forced modification of the wind field through thickness and height gradient changes versus inertial-advective effects via the diabatic component of vertical motion. Preliminary results have shown that because of the strong vertical shear over the convective region, ageostrophic response is primarily caused by the latter process. The diagnostic parameterization of convective heating has been extended for use in conjunction with satellite precipitation estimates in data-poor oceanic regions. An initial application was made to a mesoscale convective system embedded in the South Pacific convergence zone. Comparison to the heating field diagnosed as a residual in the thermodynamic equation using the ECMWF III-b analyses showed that the methodology will be useful in explaining the observed heating fields and determining the relative contribution of moist processes to the total diabatic heating. Research activities are now concentrated in the following areas: (1) Determining the sensitivity of vertical heating profiles to partitioning of gridscale versus convective precipitation; (2) assessing the possible effects of incorrect analyzed gridscale vertical motions on residuals in the heat budgets computed with the ECMWF III-b data sets.

  13. External stimulation-controllable heat-storage ceramics

    NASA Astrophysics Data System (ADS)

    Tokoro, Hiroko; Yoshikiyo, Marie; Imoto, Kenta; Namai, Asuka; Nasu, Tomomichi; Nakagawa, Kosuke; Ozaki, Noriaki; Hakoe, Fumiyoshi; Tanaka, Kenji; Chiba, Kouji; Makiura, Rie; Prassides, Kosmas; Ohkoshi, Shin-Ichi

    2015-05-01

    Commonly available heat-storage materials cannot usually store the energy for a prolonged period. If a solid material could conserve the accumulated thermal energy, then its heat-storage application potential is considerably widened. Here we report a phase transition material that can conserve the latent heat energy in a wide temperature range, T<530 K and release the heat energy on the application of pressure. This material is stripe-type lambda-trititanium pentoxide, λ-Ti3O5, which exhibits a solid-solid phase transition to beta-trititanium pentoxide, β-Ti3O5. The pressure for conversion is extremely small, only 600 bar (60 MPa) at ambient temperature, and the accumulated heat energy is surprisingly large (230 kJ L-1). Conversely, the pressure-produced beta-trititanium pentoxide transforms to lambda-trititanium pentoxide by heat, light or electric current. That is, the present system exhibits pressure-and-heat, pressure-and-light and pressure-and-current reversible phase transitions. The material may be useful for heat storage, as well as in sensor and switching memory device applications.

  14. Latent fingermark development using low-vacuum vaporization of ninhydrin.

    PubMed

    Chen, Chun-Chieh; Yang, Chao-Kai; Liao, Jeh-Shane; Wang, Sheng-Meng

    2015-12-01

    The vacuum technique is a method of vaporizing a solid material to its gas phase, helping deposit reagents gently on target surfaces to develop latent fingermarks. However, this application is rarely reported in the literature. In this study, a homemade fume hood with a built-in vacuum control system and programmable heating system designed by the Taiwan Criminal Investigation Bureau is introduced. Factors that affect the instrument's performance in developing fingermarks are discussed, including the quantity of chemicals for vaporization, heating program arrangement, and paper of different materials. The results show that fingermarks are effectively developed by vaporizing solid ninhydrin. This would be an alternative application in selecting a solvent-free method for protecting the environment and reducing health hazards in the lab. In terms of the heating program, the result indicates that under a low-vacuum condition (50 mTorr), 80-90 °C is a suitable temperature range for ninhydrin vaporization, allowing ninhydrin to be vaporized without bumping and waste. In terms of the performance on different material papers, this instrument demonstrates its capacity by developing latent fingermarks on thermal paper without discoloration or damaging the original writing, and the same results are also observed on Taiwan and United States banknotes. However, a coherent result could be hardly obtained using the same vaporization setting because different banknotes have their own surface features and water absorption ability or other unique factors may influence the effect of ninhydrin deposition. This study provides a reliable application for developing latent fingermarks without using solvents, and it is also expected to contribute to environmental protection along with the trend of green chemistry technology.

  15. Cognitive Diagnosis Using Latent Trait Models.

    ERIC Educational Resources Information Center

    Samejima, Fumiko

    This paper discusses the competency space approach to diagnosing misconceptions, skill, and knowledge acquisition. In some approaches that combine misconceptions, skill, and knowledge acquisition, the latent ability theta is used more or less as an insignificant element, but in the competency space approach, a multidimensional latent space is…

  16. Introduction to Latent Class Analysis with Applications

    ERIC Educational Resources Information Center

    Porcu, Mariano; Giambona, Francesca

    2017-01-01

    Latent class analysis (LCA) is a statistical method used to group individuals (cases, units) into classes (categories) of an unobserved (latent) variable on the basis of the responses made on a set of nominal, ordinal, or continuous observed variables. In this article, we introduce LCA in order to demonstrate its usefulness to early adolescence…

  17. A Vernacular for Linear Latent Growth Models

    ERIC Educational Resources Information Center

    Hancock, Gregory R.; Choi, Jaehwa

    2006-01-01

    In its most basic form, latent growth modeling (latent curve analysis) allows an assessment of individuals' change in a measured variable X over time. For simple linear models, as with other growth models, parameter estimates associated with the a construct (amount of X at a chosen temporal reference point) and b construct (growth in X per unit…

  18. Latent Memory for Sensitization in "Aplysia"

    ERIC Educational Resources Information Center

    Philips, Gary T.; Tzvetkova, Ekaterina I.; Marinesco, Stephane; Carew, Thomas J.

    2006-01-01

    In the analysis of memory it is commonly observed that, even after a memory is apparently forgotten, its latent presence can still be revealed in a subsequent learning task. Although well established on a behavioral level, the mechanisms underlying latent memory are not well understood. To begin to explore these mechanisms, we have used "Aplysia,"…

  19. Consequences of Fitting Nonidentified Latent Class Models

    ERIC Educational Resources Information Center

    Abar, Beau; Loken, Eric

    2012-01-01

    Latent class models are becoming more popular in behavioral research. When models with a large number of latent classes relative to the number of manifest indicators are estimated, researchers must consider the possibility that the model is not identified. It is not enough to determine that the model has positive degrees of freedom. A well-known…

  20. Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

    SciTech Connect

    Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

    2015-04-23

    We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injection strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still significant

  1. Variable Assessment in Latent Class Models

    PubMed Central

    Zhang, Q.; Ip, E. H.

    2014-01-01

    The latent class model provides an important platform for jointly modeling mixed-mode data — i.e., discrete and continuous data with various parametric distributions. Multiple mixed-mode variables are used to cluster subjects into latent classes. While the mixed-mode latent class analysis is a powerful tool for statisticians, few studies are focused on assessing the contribution of mixed-mode variables in discriminating latent classes. Novel measures are derived for assessing both absolute and relative impacts of mixed-mode variables in latent class analysis. Specifically, the expected posterior gradient and the Kolmogorov variation of the posterior distribution, as well as related properties are studied. Numerical results are presented to illustrate the measures. PMID:24910486

  2. Latent inhibition in human adults without masking.

    PubMed

    Escobar, Martha; Arcediano, Francisco; Miller, Ralph R

    2003-09-01

    Latent inhibition refers to attenuated responding to Cue X observed when the X-outcome pairings are preceded by X-alone presentations. It has proven difficult to obtain in human adults unless the preexposure (X-alone) presentations are embedded within a masking (i.e., distracting) task. The authors hypothesized that the difficulty in obtaining latent inhibition with unmasked tasks is related to the usual training procedures, in which the preexposure and conditioning experiences are separated by a set of instructions. Experiment 1 reports latent inhibition without masking in a task in which preexposure and conditioning occur without interruption. Experiments 2 and 3 demonstrate that this attenuation in responding to target Cue X does not pass a summation test for conditioned inhibition and is context specific, thereby confirming that it is latent inhibition. Experiments 3 and 4 confirm that introducing instructions between preexposure and conditioning disrupts latent inhibition.

  3. Epstein-Barr virus latent genes.

    PubMed

    Kang, Myung-Soo; Kieff, Elliott

    2015-01-23

    Latent Epstein-Barr virus (EBV) infection has a substantial role in causing many human disorders. The persistence of these viral genomes in all malignant cells, yet with the expression of limited latent genes, is consistent with the notion that EBV latent genes are important for malignant cell growth. While the EBV-encoded nuclear antigen-1 (EBNA-1) and latent membrane protein-2A (LMP-2A) are critical, the EBNA-leader proteins, EBNA-2, EBNA-3A, EBNA-3C and LMP-1, are individually essential for in vitro transformation of primary B cells to lymphoblastoid cell lines. EBV-encoded RNAs and EBNA-3Bs are dispensable. In this review, the roles of EBV latent genes are summarized.

  4. Diabatic heating, divergent circulation and moisture transport in the African monsoon system

    SciTech Connect

    Hagos, Samson M.; Zhang, Chidong

    2009-12-24

    The dynamics of the West African monsoon system is studied through the diagnosis of the roles of diabatic heating in the divergent circulation and moisture transport. The divergent circulation is partitioned into latent-heating and non-latent-heating (the sum of surface sensible heat flux and radiative heating) driven components based on its field properties and its relationship with diabatic heating profiles. Roles of latent and non-latent diabatic heating in the moisture transport of the monsoon system are thus distinguished. The gradient in surface sensible heat flux between the Saharan heat-low and the Gulf of Guinea drives a shallow meridional circulation, which transports moisture far into the continent on the northern side of the monsoon rain band and thereby promotes the seasonal northward migration of monsoon precipitation. In contrast, the circulation directly associated with latent heating is deep and the corresponding moisture convergence maximum is within the region of precipitation and thus enhances local monsoon precipitation. Meanwhile, latent heating also induces dry air advection from the north. The seasonal northward migration of precipitation is encouraged by neither of the two effects. On the other hand, the divergent circulation forced by remote latent heating influences local moisture distribution through advection. Specifically by bringing Saharan air from the north, and driving moisture to the adjacent oceans, global latent heating has an overall drying effect over the Sahel.

  5. Urban warming in the 2013 summer heat wave in eastern China

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Yan, Zhongwei; Quan, Xiao-Wei; Feng, Jinming

    2016-06-01

    The impact of urban warming during the 2013 July-August extreme heat wave event across the Yangtze River Delta (YRD) in China was assessed. Using a newly developed high-resolution, land-use dataset, urban stations were identified from a total of 101 stations in the YRD. The difference between urban and non-urban/rural stations indicates that urban warming reached 1.22 °C in the 2013 summer heat wave. The new land-use dataset was then input to the Weather Research and Forecasting model to further understand the dynamical/physical processes of the urban warming during the heat wave. The model-simulated urban warming is ~1.5 °C. Impacts of urbanization on near-surface temperature had strong diurnal variation, reaching a peak at 19:00 LST, around sunset. In the daytime, urban warming was mainly caused by enhanced sensible heat fluxes and longwave radiation from the surface. Because of reduced latent heat flux and increased heat capacity, urban ground stored much more heat than rural ground during the daytime, which is later released as sensible heat flux from the surface at night, leading to the nocturnal urban warming. The simulation results also suggest a positive feedback between urban warming and heat wave intensity, which makes the heat wave more intense in urban than rural areas and the urban warming during the extreme heat wave stronger than its climatological mean.

  6. [Possible mechanisms in latent learning formation investigated by using mutant mice].

    PubMed

    Noda, Y

    2001-03-01

    We examined possible mechanisms in the development of latent learning by methods of behavioral pharmacology and confirmed them by using mutant mice. Mice that received dopamine agonists, a noradrenergic neurotoxin or a traumatic brain injury showed impairment of latent learning. This impairment was suggested to be mediated by imbalance of dopaminergic and noradrenergic systems since the impairment was attenuated by a noradrenaline uptake inhibitor or a dopamine-D2 antagonist. The heterozygous mice for the tyrosine hydroxylase (TH) gene and for the cyclic AMP (cAMP) response element binding protein (CREB) binding protein (CBP) gene showed impairment of latent learning in the water finding task. The spatial learning and hippocampal long-term potentiation (LTP) were normal in both the mutants. TH heterozygous mice showed a reduction of high K(+)-evoked noradrenaline release in the frontal cortex by the microdialysis technique and a reduction of cAMP of the brain cAMP content. The central noradrenergic systems and/or cAMP signal pathways play an important role in latent learning, but not spatial memory. In contrast with TH and CBP mutant mice, nociceptin-knockout mice showed an enhanced retention of latent learning in the water finding task, greater learning ability in the water maze task and larger LTP than wild-type mice. Such mice showed hyperfunction of dopaminergic systems in the cortex. Nociceptin itself induced latent learning impairment in wild-type mice. These results suggest that the nociceptin system seems to play negative roles in learning and memory. In conclusion, the results of mutant mice further supported our previous results of behavioral pharmacology and suggest that the alternation of catecholamine biosynthesis and cAMP signal pathways may play a key role in development of latent learning. They further suggest that the expression of genes mediated by phosphorylated CREB may be involved in the development of latent learning.

  7. Evolution of a turbulent jet subjected to volumetric heating

    NASA Astrophysics Data System (ADS)

    Agrawal, Amit; Prasad, Ajay K.

    2004-07-01

    The goal of this study is to understand the effect of latent heat release on entrainment in cumulus clouds by employing a laboratory analogue consisting of a volumetrically heated turbulent axisymmetric jet. The jet fluid is volumetrically heated in an off-source manner to simulate condensation heat release in clouds. The experimental set-up is similar to Bhat & Narasimha (1996), and the current application of wholefield velocimetry and thermometry has allowed us to probe in detail the velocity and temperature fields within the heat injection zone (HIZ) for the first time, leading to several new results. We are able to demarcate three distinct zones within the HIZ based primarily on the nature of the cross-stream velocity profile, and we present sharp differences in flow properties in these zones. Thermochromic liquid crystal-based temperature visualizations have revealed details about the complex interplay of velocity, local concentration and temperature leading to a physically coherent understanding of this flow. We also provide evidence using linear stochastic estimates (LSE) to show that large eddies are disrupted in the latter part of the HIZ; the disruption of large eddies is linked to the change in the nature of the cross-stream velocity profile. While our results have confirmed certain previously reported observations such as a reduction in scalar width, we have measured significantly larger r.m.s. values within the HIZ than previously reported, which is corroborated by direct numerical simulation results.

  8. Orientation field estimation for latent fingerprint enhancement.

    PubMed

    Feng, Jianjiang; Zhou, Jie; Jain, Anil K

    2013-04-01

    Identifying latent fingerprints is of vital importance for law enforcement agencies to apprehend criminals and terrorists. Compared to live-scan and inked fingerprints, the image quality of latent fingerprints is much lower, with complex image background, unclear ridge structure, and even overlapping patterns. A robust orientation field estimation algorithm is indispensable for enhancing and recognizing poor quality latents. However, conventional orientation field estimation algorithms, which can satisfactorily process most live-scan and inked fingerprints, do not provide acceptable results for most latents. We believe that a major limitation of conventional algorithms is that they do not utilize prior knowledge of the ridge structure in fingerprints. Inspired by spelling correction techniques in natural language processing, we propose a novel fingerprint orientation field estimation algorithm based on prior knowledge of fingerprint structure. We represent prior knowledge of fingerprints using a dictionary of reference orientation patches. which is constructed using a set of true orientation fields, and the compatibility constraint between neighboring orientation patches. Orientation field estimation for latents is posed as an energy minimization problem, which is solved by loopy belief propagation. Experimental results on the challenging NIST SD27 latent fingerprint database and an overlapped latent fingerprint database demonstrate the advantages of the proposed orientation field estimation algorithm over conventional algorithms.

  9. Extraction of latent images from printed media

    NASA Astrophysics Data System (ADS)

    Sergeyev, Vladislav; Fedoseev, Victor

    2015-12-01

    In this paper we propose an automatic technology for extraction of latent images from printed media such as documents, banknotes, financial securities, etc. This technology includes image processing by adaptively constructed Gabor filter bank for obtaining feature images, as well as subsequent stages of feature selection, grouping and multicomponent segmentation. The main advantage of the proposed technique is versatility: it allows to extract latent images made by different texture variations. Experimental results showing performance of the method over another known system for latent image extraction are given.

  10. Technical note: physiological response of beef heifers after receiving a reused controlled internal drug release insert processed with different heat-treating methods.

    PubMed

    Dahlen, C R; Klein, S I; Lamb, G C; Mercadante, V R G; Steichen, P L

    2014-05-01

    Eighty-one prepubertal beef heifers were used to evaluate effects of used controlled internal drug release (CIDR) insert heating methods on concentrations of progesterone after CIDR insert reinsertion. Heifers were stratified by weight and birth date and then assigned to receive a new CIDR insert (New; n = 10) or 1 of 8 used (7 d prior use) CIDR insert treatments: 1) no processing (Used; n = 10), 2) autoclaved (Autoclaved; n = 8), 3) processed in dishwasher (Dishwasher; n = 8), 4) processed in microwave for 30 s (Microwave; n = 10), 5) processed in toaster oven (Oven; n = 9), 6) processed in clothes dryer (Dryer; n = 10), 7) processed in boiling water (Boiled; n = 8), or 8) stored outdoors for 60 d (Outside; n = 8). Used CIDR inserts were processed at 121°C for 30 min for autoclaved and oven treatments, at 121°C for boiled treatment, and for 30 min for dryer and dishwasher treatments. Blood samples were collected on d -10, immediately before CIDR insert insertion (d 0), 3 h after CIDR insert insertion (3 h), daily while CIDR insert was in place (d 1 to 11), and 24 h after CIDR insert removal (d 12) for analysis of concentrations of progesterone. Subjective color scores (1 = bright white to 5 = completely stained yellow/red) were assigned to each CIDR insert after d 11. A treatment × time interaction (P < 0.0001) was present for concentrations of progesterone. Concentrations of progesterone were similar (P > 0.10) for heifers receiving a used CIDR insert compared with heifers receiving CIDR inserts processed in a dishwasher, microwave, oven, dryer, or boiling water (collectively reported as "Processed"). However, heifers receiving autoclaved CIDR inserts had greater (P < 0.05) concentrations of progesterone from h 3 to d 3 but similar (P > 0.10) concentrations of progesterone from d 4 to d 11 compared with heifers receiving used or processed CIDR inserts. From d 1 to 11 heifers receiving outside CIDR inserts had decreased (P < 0.05) concentrations of progesterone

  11. Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

    DOE PAGES

    Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

    2015-04-23

    We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injectionmore » strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still

  12. Estimates of zonally averaged tropical diabatic heating in AMIP GCM simulations. PCMDI report No. 25

    SciTech Connect

    Boyle, J.S.

    1995-07-01

    An understanding of the processess that generate the atmospheric diabatic heating rates is basic to an understanding of the time averaged general circulation of the atmosphere and also circulation anomalies. Knowledge of the sources and sinks of atmospheric heating enables a fuller understanding of the nature of the atmospheric circulation. An actual assesment of the diabatic heating rates in the atmosphere is a difficult problem that has been approached in a number of ways. One way is to estimate the total diabatic heating by estimating individual components associated with the radiative fluxes, the latent heat release, and sensible heat fluxes. An example of this approach is provided by Newell. Another approach is to estimate the net heating rates from consideration of the balance required of the mass and wind variables as routinely observed and analyzed. This budget computation has been done using the thermodynamic equation and more recently done by using the vorticity and thermodynamic equations. Schaak and Johnson compute the heating rates through the integration of the isentropic mass continuity equation. The estimates of heating arrived at all these methods are severely handicapped by the uncertainties in the observational data and analyses. In addition the estimates of the individual heating components suffer an additional source of error from the parameterizations used to approximate these quantities.

  13. Multicomponent Implant Releasing Dexamethasone

    NASA Astrophysics Data System (ADS)

    Nikkola, L.; Vapalahti, K.; Ashammakhi, N.

    2008-02-01

    Several inflammatory conditions are usually treated with corticosteroids. There are various problems like side effects with traditional applications of steroids, e.g. topical, or systemic routes. Local drug delivery systems have been studied and developed to gain more efficient administration with fewer side effects. Earlier, we reported on developing Dexamethasone (DX) releasing biodegradable fibers. However, their drug release properties were not satisfactory in terms of onset of drug release. Thus, we assessed the development of multicomponent (MC) implant to enhance earlier drug release from such biodegradable fibers. Poly (lactide-co-glycolide) (PLGA) and 2 wt-% and 8 wt-% DX were compounded and extruded with twin-screw extruder to form of fibers. Some of the fibers were sterilized to obtain a change in drug release properties. Four different fiber classes were studied: 2 wt-%, 8 wt-%, sterilized 2 wt-%, and sterilized 8 wt-%. 3×4 different DX-releasing fibers were then heat-pressed to form one multicomponent rod. Half of the rods where sterilized. Drug release was measured from initial fibers and multicomponent rods using a UV/VIS spectrometer. Shear strength and changes in viscosity were also measured. Drug release studies showed that drug release commenced earlier from multicomponent rods than from component fibers. Drug release from multicomponent rods lasted from day 30 to day 70. The release period of sterilized rods extended from day 23 to day 57. When compared to the original component fibers, the drug release from MC rods commenced earlier. The initial shear strength of MC rods was 135 MPa and decreased to 105 MPa during four weeks of immersion in phosphate buffer solution. Accordingly, heat pressing has a positive effect on drug release. After four weeks in hydrolysis, no disintegration was observed.

  14. Reactivation of Latent Viruses in Space

    NASA Technical Reports Server (NTRS)

    Pierson, D. L.; Mehta, S. K.; Tyring, S. K.; Lugg, D. J.

    1999-01-01

    Reactivation of latent viruses is an important health risk for people working and living in physically isolated extreme environments such as Antarctica and space. Preflight quarantine does not significantly reduce the risk associated with latent viruses, however, pharmaceutical countermeasures are available for some viruses. The molecular basis of latency is not fully understood, but physical and psychosocial stresses are known to initiate the reactivation of latent viruses. Presumably, stress induced changes in selected hormones lead to alterations in the cell- mediated immune (CMI) response resulting in increased shedding of latent viruses. Limited access to space makes the use of ground-based analogs essential. The Australian Antarctic stations serve as a good stress model and simulate many aspects of space flight. Closed environmental chambers have been used to simulate space flight since the Skylab missions and have also proven to be a valuable analog of selected aspects of space flight.

  15. A solar-thermal energy harvesting scheme: enhanced heat capacity of molten HITEC salt mixed with Sn/SiOx core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Lai, Chih-Chung; Chang, Wen-Chih; Hu, Wen-Liang; Wang, Zhiming M.; Lu, Ming-Chang; Chueh, Yu-Lun

    2014-04-01

    We demonstrated enhanced solar-thermal storage by releasing the latent heat of Sn/SiOx core-shell nanoparticles (NPs) embedded in a eutectic salt. The microstructures and chemical compositions of Sn/SiOx core-shell NPs were characterized. In situ heating XRD provides dynamic crystalline information about the Sn/SiOx core-shell NPs during cyclic heating processes. The latent heat of ~29 J g-1 for Sn/SiOx core-shell NPs was measured, and 30% enhanced heat capacity was achieved from 1.57 to 2.03 J g-1 K-1 for the HITEC solar salt without and with, respectively, a mixture of 5% Sn/SiOx core-shell NPs. In addition, an endurance cycle test was performed to prove a stable operation in practical applications. The approach provides a method to enhance energy storage in solar-thermal power plants.We demonstrated enhanced solar-thermal storage by releasing the latent heat of Sn/SiOx core-shell nanoparticles (NPs) embedded in a eutectic salt. The microstructures and chemical compositions of Sn/SiOx core-shell NPs were characterized. In situ heating XRD provides dynamic crystalline information about the Sn/SiOx core-shell NPs during cyclic heating processes. The latent heat of ~29 J g-1 for Sn/SiOx core-shell NPs was measured, and 30% enhanced heat capacity was achieved from 1.57 to 2.03 J g-1 K-1 for the HITEC solar salt without and with, respectively, a mixture of 5% Sn/SiOx core-shell NPs. In addition, an endurance cycle test was performed to prove a stable operation in practical applications. The approach provides a method to enhance energy storage in solar-thermal power plants. Electronic supplementary information (ESI) available: Detailed experimental results are included for the following: SEM images of the HITEC molten salt with and without a mixture of Sn/SiOx core-shell NPs; statistical diameter distribution of pure Sn and Sn/SiOx core-shell NPs; the HAADF image and EDS linescan profile of a Sn/SiOx core-shell NP; XRD analysis for Sn NPs annealing at different heating

  16. Sequence-Controlled Polymers with Furan-Protected Maleimide as a Latent Monomer.

    PubMed

    Ji, Yuxuan; Zhang, Liuqiao; Gu, Xue; Zhang, Wei; Zhou, Nianchen; Zhang, Zhengbiao; Zhu, Xiulin

    2017-02-20

    Herein, a novel methodology for preparing sequence-controlled polymers is illustrated by using a latent monomer, furan protected maleimide (FMI). At 110 °C, FMI is deprotected by retro Diels-Alder (rDA) reaction, and the released MI is immediately involved in the cross-polymerization with styrene (St) to deliver heterosegments. At 40 °C the rDA reaction does not proceed, therefore homo-poly(styrene) segments are produced. By implementing programmable temperature changes during polymerization of St and FMI, "living" polymers with tailored a sequence are created. A ternary copolymerization produces complex sequences as designed. Alkynyl-functionalized FMI, used as a latent monomer, leads to the desirable placement of functional groups along the polymer chain. This latent-monomer-based strategy opens a new avenue for fabricating sequence-controlled polymers.

  17. Thermal energy storage heat exchanger: Molten salt heat exchanger design for utility power plants

    NASA Technical Reports Server (NTRS)

    Ferarra, A.; Yenetchi, G.; Haslett, R.; Kosson, R.

    1977-01-01

    Sizing procedures are presented for latent heat thermal energy storage systems that can be used for electric utility off-peak energy storage, solar power plants and other preliminary design applications.

  18. Energy released at Teide Volcano,Tenerife, Canary Islands

    NASA Astrophysics Data System (ADS)

    Lopez, D. L.; Perez, N. M.; Marrero, R.

    2003-12-01

    Teide volcano (3715 m high) is located at the northern scarp of the Las Ca¤adas caldera, a large depression at the center of Tenerife Island. Las Ca¤adas has been produced by multiple episodes of caldera collapse and giant landslides. The basanite-phonolite magmatic system associated with Teide volcano is emitting gases that reach the summit producing weak fumaroles. The chemical composition of these fumaroles and the flux of diffuse soil CO2 degassing at the summit cone (0.5 km2) has been used to determine the energy released as passive degassing in this volcano. Previous investigations show that Teide's summit is emitting 400 tons m2 day-1 of CO2 to the atmosphere. The composition of CH4, CO2, CO, and H2O indicate a chemical equilibrium temperature of 234° C and 75% condensation of water vapor within the volcanic edifice (Chiodini and Marini, 1998). The composition of the gases before condensation was restored and assumed to represent the composition at the equilibrium zone. The energy stored by the gases at the equilibration zone is assumed to be released as the gases move towards the discharge zone. The following processes are considered: change in pressure and temperature for water from the equilibration zone to the zone of condensation, latent heat released during the water condensation process, cooling of the condensed water from the condensation temperature to ambient temperature, and change of pressure and temperature for CO2 from the equilibrium to the discharge zone. Thermodynamic calculations of the energy released in each one of these processes indicate that 144 MW are released at Teide. Energy flux is 288 MW m-2. Most of this energy is released during the condensation process. This energy output compares with other hydrothermal systems of the world. These results show that during periods of passive degassing, fumarolic activity is limited by the geometry and elevation of the volcanic structure and the internal thermodynamic conditions.

  19. Habituation, latent inhibition, and extinction.

    PubMed

    Jordan, Wesley P; Todd, Travis P; Bucci, David J; Leaton, Robert N

    2015-06-01

    In two conditioned suppression experiments with a latent inhibition (LI) design, we measured the habituation of rats in preexposure, their LI during conditioning, and then extinction over days. In the first experiment, lick suppression, the preexposed group (PE) showed a significant initial unconditioned response (UR) to the target stimulus and significant long-term habituation (LTH) of that response over days. The significant difference between the PE and nonpreexposed (NPE) groups on the first conditioning trial was due solely to the difference in their URs to the conditioned stimulus (CS)-a habituated response (PE) and an unhabituated response (NPE). In the second experiment, bar-press suppression, little UR to the target stimulus was apparent during preexposure, and no detectable LTH. Thus, there was no difference between the PE and NPE groups on the first conditioning trial. Whether the UR to the CS confounds the interpretation of LI (Exp. 1) or not (Exp. 2) can only be known if the UR is measured. In both experiments, LI was observed in acquisition. Also in both experiments, rats that were preexposed and then conditioned to asymptote were significantly more resistant to extinction than were the rats not preexposed. This result contrasts with the consistently reported finding that preexposure either produces less resistance to extinction or has no effect on extinction. The effect of stimulus preexposure survived conditioning to asymptote and was reflected directly in extinction. These two experiments provide a cautionary procedural note for LI experiments and have shown an unexpected extinction effect that may provide new insights into the interpretation of LI.

  20. Omnigen-AF reduces basal plasma cortisol, AWA cortisol release to adrencocorticotropic hormone or corticotrophin releasing hormone & vasopressin in lactating dairy cows under thermoneutral or acute heat stress conditions.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Differences in the adrenal cortisol response of OmniGen-AF (OG) supplemented dairy cows to a corticotrophin releasing hormone (CRH) and vasopressin (VP) or an adrenocorticotropic hormone (ACTH) challenge when housed at different temperature-humidity indices (THI) were studied. Holstein cows (n=12; 1...

  1. New approaches in the diagnosis and treatment of latent tuberculosis infection

    PubMed Central

    2010-01-01

    With nearly 9 million new active disease cases and 2 million deaths occurring worldwide every year, tuberculosis continues to remain a major public health problem. Exposure to Mycobacterium tuberculosis leads to active disease in only ~10% people. An effective immune response in remaining individuals stops M. tuberculosis multiplication. However, the pathogen is completely eradicated in ~10% people while others only succeed in containment of infection as some bacilli escape killing and remain in non-replicating (dormant) state (latent tuberculosis infection) in old lesions. The dormant bacilli can resuscitate and cause active disease if a disruption of immune response occurs. Nearly one-third of world population is latently infected with M. tuberculosis and 5%-10% of infected individuals will develop active disease during their life time. However, the risk of developing active disease is greatly increased (5%-15% every year and ~50% over lifetime) by human immunodeficiency virus-coinfection. While active transmission is a significant contributor of active disease cases in high tuberculosis burden countries, most active disease cases in low tuberculosis incidence countries arise from this pool of latently infected individuals. A positive tuberculin skin test or a more recent and specific interferon-gamma release assay in a person without overt signs of active disease indicates latent tuberculosis infection. Two commercial interferon-gamma release assays, QFT-G-IT and T-SPOT.TB have been developed. The standard treatment for latent tuberculosis infection is daily therapy with isoniazid for nine months. Other options include therapy with rifampicin for 4 months or isoniazid + rifampicin for 3 months or rifampicin + pyrazinamide for 2 months or isoniazid + rifapentine for 3 months. Identification of latently infected individuals and their treatment has lowered tuberculosis incidence in rich, advanced countries. Similar approaches also hold great promise for other

  2. Primary Energy Efficiency Analysis of Different Separate Sensible and Latent Cooling Techniques

    SciTech Connect

    Abdelaziz, Omar

    2015-01-01

    Separate Sensible and Latent cooling (SSLC) has been discussed in open literature as means to improve air conditioning system efficiency. The main benefit of SSLC is that it enables heat source optimization for the different forms of loads, sensible vs. latent, and as such maximizes the cycle efficiency. In this paper I use a thermodynamic analysis tool in order to analyse the performance of various SSLC technologies including: multi-evaporators two stage compression system, vapour compression system with heat activated desiccant dehumidification, and integrated vapour compression with desiccant dehumidification. A primary coefficient of performance is defined and used to judge the performance of the different SSLC technologies at the design conditions. Results showed the trade-off in performance for different sensible heat factor and regeneration temperatures.

  3. Experimental Investigation of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2011-01-01

    Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.

  4. Experimental Investigation of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2012-01-01

    Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.

  5. Latent structure analysis in pharmaceutical formulations using Kohonen's self-organizing map and a Bayesian network.

    PubMed

    Kikuchi, Shingo; Onuki, Yoshinori; Yasuda, Akihito; Hayashi, Yoshihiro; Takayama, Kozo

    2011-03-01

    A latent structure analysis of pharmaceutical formulations was performed using Kohonen's self-organizing map (SOM) and a Bayesian network. A hydrophilic matrix tablet containing diltiazem hydrochloride (DTZ), a highly water-soluble model drug, was used as a model formulation. Nonlinear relationship correlations among formulation factors (oppositely charged dextran derivatives and hydroxypropyl methylcellulose), latent variables (turbidity and viscosity of the polymer mixtures and binding affinity of DTZ to polymers), and release properties [50% dissolution times (t50s) and similarity factor] were clearly visualized by self organizing feature maps. The quantities of dextran derivatives forming polyion complexes were strongly related to the binding affinity of DTZ to polymers and t50s. The latent variables were classified into five characteristic clusters with similar properties by SOM clustering. The probabilistic graphical model of the latent structure was successfully constructed using a Bayesian network. The causal relationships among the factors were quantitatively estimated by inferring conditional probability distributions. Moreover, these causal relationships estimated by the Bayesian network coincided well with estimations by SOM clustering, and the probabilistic graphical model was reflected in the characteristics of SOM clusters. These techniques provide a better understanding of the latent structure between formulation factors and responses in DTZ hydrophilic matrix tablet formulations.

  6. Vpx-containing Dendritic Cell Vaccine Vectors Induce CTLs and Reactivate Latent HIV-1 in vitro

    PubMed Central

    Norton, Thomas D.; Miller, Elizabeth A.; Bhardwaj, Nina; Landau, Nathaniel R.

    2015-01-01

    Eradication of HIV-1 from an infected individual requires a means of inducing production of virus from latently infected cells and stimulating an immune response against the infected cells. We report the development of lentiviral vectors that transduce dendritic cells (DCs) to both induce production of virus from latently infected cells and stimulate antigen-specific CTLs. The vectors package Vpx, a lentiviral accessory protein that counteracts the SAMHD1-mediated block to DC transduction, allowing for long-term expression of vector-encoded proteins. The vectors encode influenza or HIV-1-derived epitopes fused via a self-cleaving peptide to CD40L that releases the peptide into the endoplasmic reticulum for entry into the antigen presentation pathway. Expression of CD40L caused transduced DCs to mature and produce Th1-skewing cytokines. The DCs presented antigen to CD8 T cells, enhancing antigen-specific CTLs. Coculture of the transduced DCs with latently infected cells induced high level virus production, an effect that was mediated by TNF-α. The ability of a DC vaccine to reactivate latent HIV-1 and stimulate an adaptive immune response provides a means to reduce the size of the latent reservoir in patients. This strategy can also be applied to develop DC vaccines for other diseases. PMID:25567537

  7. Latent Curve Models and Latent Change Score Models Estimated in R

    ERIC Educational Resources Information Center

    Ghisletta, Paolo; McArdle, John J.

    2012-01-01

    In recent years the use of the latent curve model (LCM) among researchers in social sciences has increased noticeably, probably thanks to contemporary software developments and the availability of specialized literature. Extensions of the LCM, like the the latent change score model (LCSM), have also increased in popularity. At the same time, the R…

  8. Recombination Enhances HIV-1 Envelope Diversity by Facilitating the Survival of Latent Genomic Fragments in the Plasma Virus Population.

    PubMed

    Immonen, Taina T; Conway, Jessica M; Romero-Severson, Ethan O; Perelson, Alan S; Leitner, Thomas

    2015-12-01

    HIV-1 is subject to immune pressure exerted by the host, giving variants that escape the immune response an advantage. Virus released from activated latent cells competes against variants that have continually evolved and adapted to host immune pressure. Nevertheless, there is increasing evidence that virus displaying a signal of latency survives in patient plasma despite having reduced fitness due to long-term immune memory. We investigated the survival of virus with latent envelope genomic fragments by simulating within-host HIV-1 sequence evolution and the cycling of viral lineages in and out of the latent reservoir. Our model incorporates a detailed mutation process including nucleotide substitution, recombination, latent reservoir dynamics, diversifying selection pressure driven by the immune response, and purifying selection pressure asserted by deleterious mutations. We evaluated the ability of our model to capture sequence evolution in vivo by comparing our simulated sequences to HIV-1 envelope sequence data from 16 HIV-infected untreated patients. Empirical sequence divergence and diversity measures were qualitatively and quantitatively similar to those of our simulated HIV-1 populations, suggesting that our model invokes realistic trends of HIV-1 genetic evolution. Moreover, reconstructed phylogenies of simulated and patient HIV-1 populations showed similar topological structures. Our simulation results suggest that recombination is a key mechanism facilitating the persistence of virus with latent envelope genomic fragments in the productively infected cell population. Recombination increased the survival probability of latent virus forms approximately 13-fold. Prevalence of virus with latent fragments in productively infected cells was observed in only 2% of simulations when we ignored recombination, while the proportion increased to 27% of simulations when we allowed recombination. We also found that the selection pressures exerted by different fitness

  9. Recombination enhances HIV-1 envelope diversity by facilitating the survival of latent genomic fragments in the plasma virus population

    SciTech Connect

    Immonen, Taina T.; Conway, Jessica M.; Romero-Severson, Ethan O.; Perelson, Alan S.; Leitner, Thomas; Kouyos, Roger Dimitri

    2015-12-22

    HIV-1 is subject to immune pressure exerted by the host, giving variants that escape the immune response an advantage. Virus released from activated latent cells competes against variants that have continually evolved and adapted to host immune pressure. Nevertheless, there is increasing evidence that virus displaying a signal of latency survives in patient plasma despite having reduced fitness due to long-term immune memory. We investigated the survival of virus with latent envelope genomic fragments by simulating within-host HIV-1 sequence evolution and the cycling of viral lineages in and out of the latent reservoir. Our model incorporates a detailed mutation process including nucleotide substitution, recombination, latent reservoir dynamics, diversifying selection pressure driven by the immune response, and purifying selection pressure asserted by deleterious mutations. We evaluated the ability of our model to capture sequence evolution in vivo by comparing our simulated sequences to HIV-1 envelope sequence data from 16 HIV-infected untreated patients. Empirical sequence divergence and diversity measures were qualitatively and quantitatively similar to those of our simulated HIV-1 populations, suggesting that our model invokes realistic trends of HIV-1 genetic evolution. Moreover, reconstructed phylogenies of simulated and patient HIV-1 populations showed similar topological structures. Our simulation results suggest that recombination is a key mechanism facilitating the persistence of virus with latent envelope genomic fragments in the productively infected cell population. Recombination increased the survival probability of latent virus forms approximately 13-fold. Prevalence of virus with latent fragments in productively infected cells was observed in only 2% of simulations when we ignored recombination, while the proportion increased to 27% of simulations when we allowed recombination. We also found that the selection pressures exerted by different fitness

  10. Recombination Enhances HIV-1 Envelope Diversity by Facilitating the Survival of Latent Genomic Fragments in the Plasma Virus Population

    PubMed Central

    Immonen, Taina T.; Conway, Jessica M.; Romero-Severson, Ethan O.; Perelson, Alan S.; Leitner, Thomas

    2015-01-01

    HIV-1 is subject to immune pressure exerted by the host, giving variants that escape the immune response an advantage. Virus released from activated latent cells competes against variants that have continually evolved and adapted to host immune pressure. Nevertheless, there is increasing evidence that virus displaying a signal of latency survives in patient plasma despite having reduced fitness due to long-term immune memory. We investigated the survival of virus with latent envelope genomic fragments by simulating within-host HIV-1 sequence evolution and the cycling of viral lineages in and out of the latent reservoir. Our model incorporates a detailed mutation process including nucleotide substitution, recombination, latent reservoir dynamics, diversifying selection pressure driven by the immune response, and purifying selection pressure asserted by deleterious mutations. We evaluated the ability of our model to capture sequence evolution in vivo by comparing our simulated sequences to HIV-1 envelope sequence data from 16 HIV-infected untreated patients. Empirical sequence divergence and diversity measures were qualitatively and quantitatively similar to those of our simulated HIV-1 populations, suggesting that our model invokes realistic trends of HIV-1 genetic evolution. Moreover, reconstructed phylogenies of simulated and patient HIV-1 populations showed similar topological structures. Our simulation results suggest that recombination is a key mechanism facilitating the persistence of virus with latent envelope genomic fragments in the productively infected cell population. Recombination increased the survival probability of latent virus forms approximately 13-fold. Prevalence of virus with latent fragments in productively infected cells was observed in only 2% of simulations when we ignored recombination, while the proportion increased to 27% of simulations when we allowed recombination. We also found that the selection pressures exerted by different fitness

  11. Phase-Change Heat-Storage Module

    NASA Technical Reports Server (NTRS)

    Mulligan, James C.

    1989-01-01

    Heat-storage module accommodates momentary heating or cooling overload in pumped-liquid heat-transfer system. Large heat-storage capacity of module provided by heat of fusion of material that freezes at or near temperature desired to maintain object to be heated or cooled. Module involves relatively small penalties in weight, cost, and size and more than compensates by enabling design of rest of system to handle only average load. Latent heat of fusion of phase-change material provides large heat-storage capacity in small volume.

  12. Proliferation of latently infected CD4(+) T cells carrying replication-competent HIV-1: Potential role in latent reservoir dynamics.

    PubMed

    Hosmane, Nina N; Kwon, Kyungyoon J; Bruner, Katherine M; Capoferri, Adam A; Beg, Subul; Rosenbloom, Daniel I S; Keele, Brandon F; Ho, Ya-Chi; Siliciano, Janet D; Siliciano, Robert F

    2017-04-03

    A latent reservoir for HIV-1 in resting CD4(+) T lymphocytes precludes cure. Mechanisms underlying reservoir stability are unclear. Recent studies suggest an unexpected degree of infected cell proliferation in vivo. T cell activation drives proliferation but also reverses latency, resulting in productive infection that generally leads to cell death. In this study, we show that latently infected cells can proliferate in response to mitogens without producing virus, generating progeny cells that can release infectious virus. Thus, assays relying on one round of activation underestimate reservoir size. Sequencing of independent clonal isolates of replication-competent virus revealed that 57% had env sequences identical to other isolates from the same patient. Identity was confirmed by full-genome sequencing and was not attributable to limited viral diversity. Phylogenetic and statistical analysis suggested that identical sequences arose from in vivo proliferation of infected cells, rather than infection of multiple cells by a dominant viral species. The possibility that much of the reservoir arises by cell proliferation presents challenges to cure.

  13. Proliferation of latently infected CD4+ T cells carrying replication-competent HIV-1: Potential role in latent reservoir dynamics

    PubMed Central

    Hosmane, Nina N.; Kwon, Kyungyoon J.; Bruner, Katherine M.; Capoferri, Adam A.; Rosenbloom, Daniel I.S.; Keele, Brandon F.; Ho, Ya-Chi

    2017-01-01

    A latent reservoir for HIV-1 in resting CD4+ T lymphocytes precludes cure. Mechanisms underlying reservoir stability are unclear. Recent studies suggest an unexpected degree of infected cell proliferation in vivo. T cell activation drives proliferation but also reverses latency, resulting in productive infection that generally leads to cell death. In this study, we show that latently infected cells can proliferate in response to mitogens without producing virus, generating progeny cells that can release infectious virus. Thus, assays relying on one round of activation underestimate reservoir size. Sequencing of independent clonal isolates of replication-competent virus revealed that 57% had env sequences identical to other isolates from the same patient. Identity was confirmed by full-genome sequencing and was not attributable to limited viral diversity. Phylogenetic and statistical analysis suggested that identical sequences arose from in vivo proliferation of infected cells, rather than infection of multiple cells by a dominant viral species. The possibility that much of the reservoir arises by cell proliferation presents challenges to cure. PMID:28341641

  14. Tensor Decompositions for Learning Latent Variable Models

    DTIC Science & Technology

    2012-12-08

    of a tensor, 2011. arXiv:1004.4953. [CSC+12] S. B. Cohen, K. Stratos, M. Collins, D. P. Foster, and L. Ungar . Spectral learning of latent-variable...12] P. S. Dhillon, J. Rodu, M. Collins, D. P. Foster, and L. H. Ungar . Spectral dependency parsing with latent variables. In EMNLP-CoNLL, 2012. [DS07...Foster, J. Rodu, and L. H. Ungar . Spectral dimensionality reduction for HMMs, 2012. arXiv:1203.6130. [GvL96] G. H. Golub and C. F. van Loan. Matrix

  15. Intractable diarrhoea of infancy and latent otomastoiditis.

    PubMed Central

    Salazar de Sousa, J; da Silva, A; da Costa Ribeiro, V

    1980-01-01

    In 16 infants with intractable diarrhoea, latent otomastoiditis was found in 9 (3 at necropsy and 6 at myringotomy-antrotomy). In 5 of the 6 operated group, surgery was followed by a striking cessation of the diarrhoea and with weight gain. It is concluded that (1) latent otomastoiditis may be a perpetuating factor in intractable diarrhoea; (2) myringotomy-antrotomy should be considered if other forms of treatment have failed, and especially if there is leucocytosis; (3) mastoiditis with diffuse osteitis seems to be associated with a poor prognosis. PMID:7458392

  16. Latent Tuberculosis in Pregnancy: A Systematic Review

    PubMed Central

    Malhamé, Isabelle; Cormier, Maxime; Sugarman, Jordan; Schwartzman, Kevin

    2016-01-01

    Background In countries with low tuberculosis (TB) incidence, immigrants from higher incidence countries represent the major pool of individuals with latent TB infection (LTBI). The antenatal period represents an opportunity for immigrant women to access the medical system, and hence for potential screening and treatment of LTBI. However, such screening and treatment during pregnancy remains controversial. Objectives In order to further understand the prevalence, natural history, screening and management of LTBI in pregnancy, we conducted a systematic literature review addressing the screening and treatment of LTBI, in pregnant women without known HIV infection. Methods A systematic review of 4 databases (Embase, Embase Classic, Medline, Cochrane Library) covering articles published from January 1st 1980 to April 30th 2014. Articles in English, French or Spanish with relevant information on prevalence, natural history, screening tools, screening strategies and treatment of LTBI during pregnancy were eligible for inclusion. Articles were excluded if (1) Full text was not available (2) they were case series or case studies (3) they focused exclusively on prevalence, diagnosis and treatment of active TB (4) the study population was exclusively HIV-infected. Results Of 4,193 titles initially identified, 208 abstracts were eligible for review. Of these, 30 articles qualified for full text review and 22 were retained: 3 cohort studies, 2 case-control studies, and 17 cross-sectional studies. In the USA, the estimated prevalence of LTBI ranged from 14 to 48% in women tested, and tuberculin skin test (TST) positivity was associated with ethnicity. One study suggested that incidence of active TB was significantly increased during the 180 days postpartum (Incidence rate ratio, 1.95 (95% CI 1.24–3.07). There was a high level of adherence with both skin testing (between 90–100%) and chest radiography (93–100%.). In three studies from low incidence settings, concordance

  17. Anthropogenic heat flux estimation from space: first results

    NASA Astrophysics Data System (ADS)

    Chrysoulakis, Nektarios; Heldens, Wieke; Gastellu-Etchegorry, Jean-Philippe; Grimmond, Sue; Feigenwinter, Christian; Lindberg, Fredrik; Del Frate, Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Albitar, Ahmad; Gabey, Andrew; Parlow, Eberhard; Olofson, Frans

    2016-04-01

    While Earth Observation (EO) has made significant advances in the study of urban areas, there are several unanswered science and policy questions to which it could contribute. To this aim the recently launched Horizon 2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of EO to retrieve anthropogenic heat flux, as a key component in the urban energy budget. The anthropogenic heat flux is the heat flux resulting from vehicular emissions, space heating and cooling of buildings, industrial processing and the metabolic heat release by people. Optical, thermal and SAR data from existing satellite sensors are used to improve the accuracy of the radiation balance spatial distribution calculation, using also in-situ reflectance measurements of urban materials are for calibration. EO-based methods are developed for estimating turbulent sensible and latent heat fluxes, as well as urban heat storage flux and anthropogenic heat flux spatial patterns at city scale and local scale by employing an energy budget closure approach. Independent methods and models are engaged to evaluate the derived products and statistical analyses provide uncertainty measures as well. Ultimate goal of the URBANFLUXES is to develop a highly automated method for estimating urban energy budget components to use with Copernicus Sentinel data, enabling its integration into applications and operational services. Thus, URBANFLUXES prepares the ground for further innovative exploitation of European space data in scientific activities (i.e. Earth system modelling and climate change studies in cities) and future and emerging applications (i.e. sustainable urban planning) by exploiting the improved data quality, coverage and revisit times of the Copernicus data. The URBANFLUXES products will therefore have the potential to support both sustainable planning strategies to improve the quality of life in cities, as well as Earth system models to

  18. Immune Function and Reactivation of Latent Viruses

    NASA Technical Reports Server (NTRS)

    Butel, Janet S.

    1999-01-01

    A major concern associated with long-duration space flight is the possibility of infectious diseases posing an unacceptable medical risk to crew members. One major hypothesis addressed in this project is that space flight will cause alterations in the immune system that will allow latent viruses that are endogenous in the human population to reactivate and shed to higher levels than normal, which may affect the health of crew members. The second major hypothesis being examined is that the effects of space flight will alter the mucosal immune system, the first line of defense against many microbial infections, including herpesviruses, polyomaviruses, and gastroenteritis viruses, rendering crew members more susceptible to virus infections across the mucosa. We are focusing the virus studies on the human herpesviruses and polyomaviruses, important pathogens known to establish latent infections in most of the human population. Both primary infection and reactivation from latent infection with these groups of viruses (especially certain herpesviruses) can cause a variety of illnesses that result in morbidity and, occasionally, mortality. Both herpesviruses and polyomaviruses have been associated with human cancer, as well. Effective vaccines exist for only one of the eight known human herpesviruses and available antivirals are of limited use. Whereas normal individuals display minimal consequences from latent viral infections, events which alter immune function (such as immunosuppressive therapy following solid organ transplantation) are known to increase the risk of complications as a result of viral reactivations.

  19. Generalized Structured Component Analysis with Latent Interactions

    ERIC Educational Resources Information Center

    Hwang, Heungsun; Ho, Moon-Ho Ringo; Lee, Jonathan

    2010-01-01

    Generalized structured component analysis (GSCA) is a component-based approach to structural equation modeling. In practice, researchers may often be interested in examining the interaction effects of latent variables. However, GSCA has been geared only for the specification and testing of the main effects of variables. Thus, an extension of GSCA…

  20. CICATRIZATION OF WOUNDS : XI. LATENT PERIOD.

    PubMed

    Carrel, A; du Noüy, P L

    1921-09-30

    1. The latent period of cicatrization varies generally from 5 to 7 days. 2. It stops abruptly and contraction starts with its maximum velocity. 3. The formula of du Noüy applies to the beginning of the contraction period as well as to the subsequent periods.

  1. Detection of latent prints by Raman imaging

    DOEpatents

    Lewis, Linda Anne [Andersonville, TN; Connatser, Raynella Magdalene [Knoxville, TN; Lewis, Sr., Samuel Arthur

    2011-01-11

    The present invention relates to a method for detecting a print on a surface, the method comprising: (a) contacting the print with a Raman surface-enhancing agent to produce a Raman-enhanced print; and (b) detecting the Raman-enhanced print using a Raman spectroscopic method. The invention is particularly directed to the imaging of latent fingerprints.

  2. An Introduction to Latent Semantic Analysis.

    ERIC Educational Resources Information Center

    Landauer, Thomas K; Foltz, Peter W.; Laham, Darrell

    1998-01-01

    Offers an introduction to the theory and implementation of Latent Semantic Analysis (LSA), a theory and method for extracting and representing the contextual-usage meaning of words by statistical computations applied to a large corpus of text. Gives an overview of applications and modeling of human knowledge to which LSA has been applied. (SR)

  3. Essay Assessment with Latent Semantic Analysis

    ERIC Educational Resources Information Center

    Miller, Tristan

    2003-01-01

    Latent semantic analysis (LSA) is an automated, statistical technique for comparing the semantic similarity of words or documents. In this article, I examine the application of LSA to automated essay scoring. I compare LSA methods to earlier statistical methods for assessing essay quality, and critically review contemporary essay-scoring systems…

  4. Forensic Chemistry: The Revelation of Latent Fingerprints

    ERIC Educational Resources Information Center

    Friesen, J. Brent

    2015-01-01

    The visualization of latent fingerprints often involves the use of a chemical substance that creates a contrast between the fingerprint residues and the surface on which the print was deposited. The chemical-aided visualization techniques can be divided into two main categories: those that chemically react with the fingerprint residue and those…

  5. Component Latent Trait Models for Test Design.

    ERIC Educational Resources Information Center

    Embretson, Susan Whitely

    Latent trait models are presented that can be used for test design in the context of a theory about the variables that underlie task performance. Examples of methods for decomposing and testing hypotheses about the theoretical variables in task performance are given. The methods can be used to determine the processing components that are involved…

  6. Extended Generalized Linear Latent and Mixed Model

    ERIC Educational Resources Information Center

    Segawa, Eisuke; Emery, Sherry; Curry, Susan J.

    2008-01-01

    The generalized linear latent and mixed modeling (GLLAMM framework) includes many models such as hierarchical and structural equation models. However, GLLAMM cannot currently accommodate some models because it does not allow some parameters to be random. GLLAMM is extended to overcome the limitation by adding a submodel that specifies a…

  7. Latent mnemonic strengths are latent: a comment on Mickes, Wixted, and Wais (2007).

    PubMed

    Rouder, Jeffrey N; Pratte, Michael S; Morey, Richard D

    2010-06-01

    Mickes, Wixted, and Wais (2007) proposed a simple test of latent strength variability in recognition memory. They asked participants to rate their confidence using either a 20-point or a 99-point strength scale and plotted distributions of the resulting ratings. They found 25% more variability in ratings for studied than for new items, which they interpreted as providing evidence that latent mnemonic strength distributions are 25% more variable for studied than for new items. We show here that this conclusion is critically dependent on assumptions--so much so that these assumptions determine the conclusions. In fact, opposite conclusions, such that study does not affect the variability of latent strength, may be reached by making different but equally plausible assumptions. Because all measurements of mnemonic strength variability are critically dependent on untestable assumptions, all are arbitrary. Hence, there is no principled method for assessing the relative variability of latent mnemonic strength distributions.

  8. Crystallization, sublimation, and gas release in the interior of a porous comet nucleus

    NASA Technical Reports Server (NTRS)

    Prialnik, Dina

    1992-01-01

    A numerical code is developed for evolutionary calculations of the thermal structure and composition of a porous comet nucleus made of water ice, in amorphous or crystalline form, other volatiles, dust, and gases trapped in amorphous ice. Bulk evaporation, crystallization, gas release, and free (Knudsen) flow of gases through the pores are taken into account. The numerical scheme yields exact conservation laws for mass and energy. The code is used to study the effect of bulk evaporation of ice in the interior of a comet nucleus during crystallization. It is found that evaporation controls the temperature distribution; the vapor prevents cooling of the crystallized layer of ice, by recondensation and release of latent heat. Thus high temperatures are maintained below the surface of the nucleus and down to depths of tens or hundreds of meters, even at large heliocentric distances, as long as crystallization goes on. Gas trapped in the ice and released during the phase transition flows both toward the interior and toward the surface and out of the nucleus. The progress of crystallization is largely determined by the contribution of gas fluxes to heat transfer.

  9. Reactions of latent prints exposed to blood.

    PubMed

    Praska, Nicole; Langenburg, Glenn

    2013-01-10

    We explored whether an undeveloped latent print (fingermark) exposed to blood and later developed by enhancement with blood reagents such as amido black (AB) or leucocrystal violet (LCV) could appear as a genuine blood mark. We examined three different experimental conditions. In Experiment I, fingermark residue only was tested, as a control to confirm that fingermark residue alone does not react with the blood reagents AB and LCV. Experiment II investigated whether latent fingermarks exposed to blood dilutions could be treated with AB or LCV and subsequently appear as a genuine blood mark enhanced with AB or LCV. Experiment III tested whether latent fingermarks exposed to whole blood could be processed with AB or LCV and subsequently appear as a genuine blood mark enhanced with AB or LCV. The present study found that indeed, fingermark residue alone does not react with the blood reagents AB and LCV. In Experiment II, an interaction occurred between the fingermark residue and the diluted blood that caused the ridges to appear a red color. In the present study, this interaction is called a faux blood mark. While the faux blood mark phenomenon occurred most often following exposure to diluted blood, it did not occur consistently, and a predictable pattern could not be established. However, the reaction occurred more frequently following extended fingermark residue drying times. Faux blood marks are distinguishable from genuine blood marks prior to enhancement with blood reagents. Following treatment with blood reagents, it became increasingly difficult to determine whether the enhanced mark was a genuine blood print or a latent fingermark exposed to diluted blood. Latent fingermarks exposed to whole blood often resulted in a void prior to enhancement, but following treatment with blood reagents, were difficult to distinguish from a genuine blood mark enhanced with blood reagents.

  10. A Latent Variable Approach to the Simple View of Reading

    ERIC Educational Resources Information Center

    Kershaw, Sarah; Schatschneider, Chris

    2012-01-01

    The present study utilized a latent variable modeling approach to examine the Simple View of Reading in a sample of students from 3rd, 7th, and 10th grades (N = 215, 188, and 180, respectively). Latent interaction modeling and other latent variable models were employed to investigate (a) the functional form of the relationship between decoding and…

  11. The latent cytomegalovirus decreases telomere length by microcompetition

    PubMed Central

    Javaherian, Adrian

    2015-01-01

    Reduced telomere length has been associated with aging and age-related diseases. Latent infection with the Cytomegalovirus (CMV) induces telomere shortening in the infected cells. Latent CMV infection may cause reduced telomere length via GABP transcription factor deficiency, according to the Microcompetition Theory. Microcompetition and viral-induced transcription factor deficiency is important since most people harbor a latent viral infection.

  12. Bayesian Semiparametric Structural Equation Models with Latent Variables

    ERIC Educational Resources Information Center

    Yang, Mingan; Dunson, David B.

    2010-01-01

    Structural equation models (SEMs) with latent variables are widely useful for sparse covariance structure modeling and for inferring relationships among latent variables. Bayesian SEMs are appealing in allowing for the incorporation of prior information and in providing exact posterior distributions of unknowns, including the latent variables. In…

  13. Skills Diagnosis Using IRT-Based Continuous Latent Trait Models

    ERIC Educational Resources Information Center

    Stout, William

    2007-01-01

    This article summarizes the continuous latent trait IRT approach to skills diagnosis as particularized by a representative variety of continuous latent trait models using item response functions (IRFs). First, several basic IRT-based continuous latent trait approaches are presented in some detail. Then a brief summary of estimation, model…

  14. Modeling Interaction Effects in Latent Growth Curve Models.

    ERIC Educational Resources Information Center

    Li, Fuzhong; Duncan, Terry E.; Acock, Alan

    2000-01-01

    Presents an extension of the method of estimating interaction effects among latent variables to latent growth curve models developed by K. Joreskog and F. Yang (1996). Illustrates the procedure and discusses results in terms of practical and statistical problems associated with interaction analyses in latent curve models and structural equation…

  15. Stochastic Approximation Methods for Latent Regression Item Response Models

    ERIC Educational Resources Information Center

    von Davier, Matthias; Sinharay, Sandip

    2010-01-01

    This article presents an application of a stochastic approximation expectation maximization (EM) algorithm using a Metropolis-Hastings (MH) sampler to estimate the parameters of an item response latent regression model. Latent regression item response models are extensions of item response theory (IRT) to a latent variable model with covariates…

  16. Using Latent Class Analysis To Set Academic Performance Standards.

    ERIC Educational Resources Information Center

    Brown, Richard S.

    The use of latent class analysis for establishing student performance standards was studied. Latent class analysis (LCA) is an established procedure for investigating the latent structure of a set of data. LCA presumes that groups, classes, or respondents differ qualitatively from one another, and that these differences account for all of the…

  17. Fingerprint Minutiae from Latent and Matching Tenprint Images

    National Institute of Standards and Technology Data Gateway

    NIST Fingerprint Minutiae from Latent and Matching Tenprint Images (PC database for purchase)   NIST Special Database 27 contains latent fingerprints from crime scenes and their matching rolled fingerprint mates. This database can be used to develop and test new fingerprint algorithms, test commercial and research AFIS systems, train latent examiners, and promote the ANSI/NIST file format standard.

  18. A General Approach to Defining Latent Growth Components

    ERIC Educational Resources Information Center

    Mayer, Axel; Steyer, Rolf; Mueller, Horst

    2012-01-01

    We present a 3-step approach to defining latent growth components. In the first step, a measurement model with at least 2 indicators for each time point is formulated to identify measurement error variances and obtain latent variables that are purged from measurement error. In the second step, we use contrast matrices to define the latent growth…

  19. Modeling Nonlinear Change via Latent Change and Latent Acceleration Frameworks: Examining Velocity and Acceleration of Growth Trajectories

    ERIC Educational Resources Information Center

    Grimm, Kevin; Zhang, Zhiyong; Hamagami, Fumiaki; Mazzocco, Michele

    2013-01-01

    We propose the use of the latent change and latent acceleration frameworks for modeling nonlinear growth in structural equation models. Moving to these frameworks allows for the direct identification of "rates of change" and "acceleration" in latent growth curves--information available indirectly through traditional growth…

  20. Treatment guidelines for latent tuberculosis infection.

    PubMed

    2014-01-01

    The treatment of latent tuberculosis infection (LTBI) has been established as valid for patients at high risk for developing active tuberculosis. Treatment of LTBI is also considered an important strategy for eliminating tuberculosis (TB) in Japan. In recent years, interferon-gamma release assays have come into widespread use; isoniazid (INH) preventive therapy for HIV patients has come to be recommended worldwide; and there have been increases in both types of biologics used in the treatment of immune diseases as well as the diseases susceptible to treatment. In light of the above facts, the Prevention Committee and the Treatment Committee of the Japanese Society for Tuberculosis have jointly drafted these guidelines. In determining subjects for LTBI treatment, the following must be considered: 1) risk of TB infection/ development; 2) infection diagnosis; 3) chest image diagnosis; 4) the impact of TB development; 5) the possible manifestation of side effects; and 6) the prospects of treatment completion. LTBI treatment is actively considered when relative risk is deemed 4 or higher, including risk factors such as the following: HIV/AIDS, organ transplants (immunosuppressant use), silicosis, dialysis due to chronic renal failure, recent TB infection (within 2 years), fibronodular shadows in chest radiographs (untreated old TB), the use of biologics, and large doses of corticosteroids. Although the risk is lower, the following risk factors require consideration of LTBI treatment when 2 or more of them are present: use of oral or inhaled corticosteroids, use of other immunosuppressants, diabetes, being underweight, smoking, gastrectomy, and so on. In principle, INH is administered for a period of 6 or 9 months. When INH cannot be used, rifampicin is administered for a period of 4 or 6 months. It is believed that there are no reasons to support long-term LTBI treatment for immunosuppressed patients in Japan, where the risk of infection is not considered markedly high

  1. Two Studies of Specification Error in Models for Categorical Latent Variables

    ERIC Educational Resources Information Center

    Kaplan, David; Depaoli, Sarah

    2011-01-01

    This article examines the problem of specification error in 2 models for categorical latent variables; the latent class model and the latent Markov model. Specification error in the latent class model focuses on the impact of incorrectly specifying the number of latent classes of the categorical latent variable on measures of model adequacy as…

  2. The algebraic theory of latent projectors in lambda matrices

    NASA Technical Reports Server (NTRS)

    Denman, E. D.; Leyva-Ramos, J.; Jeon, G. J.

    1981-01-01

    Multivariable systems such as a finite-element model of vibrating structures, control systems, and large-scale systems are often formulated in terms of differential equations which give rise to lambda matrices. The present investigation is concerned with the formulation of the algebraic theory of lambda matrices and the relationship of latent roots, latent vectors, and latent projectors to the eigenvalues, eigenvectors, and eigenprojectors of the companion form. The chain rule for latent projectors and eigenprojectors for the repeated latent root or eigenvalues is given.

  3. Activation of a heat-stable cytolytic protein associated with the surface membrane of Naegleria fowleri.

    PubMed Central

    Lowrey, D M; McLaughlin, J

    1985-01-01

    Surface membrane-enriched fractions of Naegleria fowleri obtained after isopycnic centrifugation experiments contain a potent cytolytic activity as determined by hemolysis and 51Cr release assays. This surface membrane cytolysin was unaffected by a treatment at 75 degrees C for 30 min and accounted for 70 to 90% of cytolysis by whole-cell lysates of amoebae. This heat resistance as well as intimate membrane association distinguished the surface membrane cytolytic activity from a second heat-labile cytolytic activity which appears to be latent within lysosomes. The surface membrane cytolysin was found to be specifically activated by diluted samples of lysosomal fractions. The possible role of this surface membrane cytotoxin in the pathogenicity of N. fowleri is discussed. PMID:4055029

  4. Encapsulated nano-heat-sinks for thermal management of heterogeneous chemical reactions.

    PubMed

    Zhang, Minghui; Hong, Yan; Ding, Shujiang; Hu, Jianjun; Fan, Yunxiao; Voevodin, Andrey A; Su, Ming

    2010-12-01

    This paper describes a new way to control temperatures of heterogeneous exothermic reactions such as heterogeneous catalytic reaction and polymerization by using encapsulated nanoparticles of phase change materials as thermally functional additives. Silica-encapsulated indium nanoparticles and silica encapsulated paraffin nanoparticles are used to absorb heat released in catalytic reaction and to mitigate gel effect of polymerization, respectively. The local hot spots that are induced by non-homogenous catalyst packing, reactant concentration fluctuation, and abrupt change of polymerization rate lead to solid to liquid phase change of nanoparticle cores so as to avoid thermal runaway by converting energies from exothermic reactions to latent heat of fusion. By quenching local hot spots at initial stage, reaction rates do not rise significantly because the thermal energy produced in reaction is isothermally removed. Nanoparticles of phase change materials will open a new dimension for thermal management of exothermic reactions to quench local hot spots, prevent thermal runaway of reaction, and change product distribution.

  5. Encapsulated nano-heat-sinks for thermal management of heterogeneous chemical reactions

    NASA Astrophysics Data System (ADS)

    Zhang, Minghui; Hong, Yan; Ding, Shujiang; Hu, Jianjun; Fan, Yunxiao; Voevodin, Andrey A.; Su, Ming

    2010-12-01

    This paper describes a new way to control temperatures of heterogeneous exothermic reactions such as heterogeneous catalytic reaction and polymerization by using encapsulated nanoparticles of phase change materials as thermally functional additives. Silica-encapsulated indiumnanoparticles and silica encapsulated paraffin nanoparticles are used to absorb heat released in catalytic reaction and to mitigate gel effect of polymerization, respectively. The local hot spots that are induced by non-homogenous catalyst packing, reactant concentration fluctuation, and abrupt change of polymerization rate lead to solid to liquid phase change of nanoparticle cores so as to avoid thermal runaway by converting energies from exothermic reactions to latent heat of fusion. By quenching local hot spots at initial stage, reaction rates do not rise significantly because the thermal energy produced in reaction is isothermally removed. Nanoparticles of phase change materials will open a new dimension for thermal management of exothermic reactions to quench local hot spots, prevent thermal runaway of reaction, and change product distribution.

  6. Analysis of snowpack accumulation and the melting process of wet snow using a heat balance approach that emphasizes the role of underground heat flux

    NASA Astrophysics Data System (ADS)

    Maruyama, Toshisuke; Takimoto, Hiroshi; Ogura, Akira; Yoshida, Masashi

    2015-03-01

    Snowpack accumulation and melting, including the role of the heat flux underground, were investigated by employing the bulk transfer method and setting roughness lengths of ZO = ZT = 0.005 m and ZT = 0.007 m. Heat balance data were recorded for a period of 4 years, from the fall of 2009 to the spring of 2013, at a forest experiment station in the Hokuriku region, which lies along the Japan Sea. The findings of the research are as follows: (1) The observed temporal changes in the snowpack depth were well reproduced by our model using observed and estimated densities. (2) The importance and roles of the heat balance components were clarified. The total heat input during the 4 years was 252.2 MJ/m2 on average; 41.4% was provided by net radiation (Rn), 37.8% by sensible heat flux (H), and 13.2% by underground heat flux (G). The total output was 120.7 MJ/m2, of which 56.2% was accounted for by Rn and 31.1% by latent heat flux (lE). (3) Of the total heat input, 45.2% was released as freezing energy from the surface side and 2.6% was released from the bottom. (4) In the very cold season (December-February), the total input energy was 115.8 MJ/m2 on average; 75.0% was supplied by the surface and the remaining 25.0% from underground. In an anomalous year, 40.8% of the energy was supplied from underground.

  7. New tests will improve detection of latent TB.

    PubMed

    Chapman, Ann L N

    2011-11-01

    In the UK cases of active TB have risen substantially over the past 20 years. This increase has occurred almost exclusively in individuals born outside the UK, who now constitute more than two-thirds of cases. Only around one in ten people who are infected will develop active disease. The remaining 90% are presumed to have latent TB infection (LTBI) where viable mycobacteria are thought to persist for decades, and may reactivate if the host's immune system is weakened. In a country such as the UK with a low incidence of TB, a high proportion of cases result from reactivation of latent TB, rather than transmission by infectious cases. In the past 10 years a novel type of diagnostic test for LTBI has been developed: the interferon-gamma release assays (IGRA). Their major advantage over the tuberculin skin test is that they are not affected by prior BCG vaccination and they have a specificity of well over 90%. These tests are unable to distinguish between active and latent TB infection: this distinction must be performed purely on clinical grounds. Patients with a positive test should be assessed by a clinician with expertise in TB to ensure an appropriate management plan for each patient. The role of IGRAs in diagnosis of active TB is limited since in a patient with suspected active TB a positive result may indicate LTBI in combination with an alternative diagnosis. At a population level screening and chemoprophylaxis contributes usefully to TB control. However, only those under 35 with LTBI should receive prophylaxis. After this age the increasing risks of hepatotoxicity begin to outweigh the diminishing benefits of prophylaxis. The exceptions are healthcare workers, where the benefits are not just to the individual but also extend to their patients, and immunocompromised patients. The IGRAs represent a major development in the diagnosis of LTBI. While currently most of their use is through established TB screening services, it is likely in future that they will

  8. Blocking of potentiation of latent inhibition.

    PubMed

    Hall, Geoffrey; Rodriguez, Gabriel

    2011-01-01

    We present a theory of latent inhibition based on the Pearce-Hall (Pearce & Hall, 1980) model for classical conditioning. Its central features are (1) that the associability of a stimulus declines as it comes to predict its consequences and (2) that nonreinforced exposure to a stimulus engages an associative learning process that makes the stimulus an accurate predictor of its consequences (in this case, the occurrence of no event). A formalization of this theory is shown to accommodate the finding that preexposure in compound with another cue can potentiate latent inhibition to the target cue. It further predicts that preexposure to the added cue will eliminate the potentiation effect. An experiment using rats and the flavor-aversion procedure confirmed this prediction.

  9. Energy-Storage Modules for Active Solar Heating and Cooling

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1982-01-01

    34 page report describes a melting salt hydrate that stores 12 times as much heat as rocks and other heavy materials. Energy is stored mostly as latent heat; that is, heat that can be stored and recovered without any significant change in temperature. Report also describes development, evaluation and testing of permanently sealed modules containing salt hydrate mixture.

  10. The latent class multitrait-multimethod model.

    PubMed

    Oberski, Daniel L; Hagenaars, Jacques A P; Saris, Willem E

    2015-12-01

    A latent class multitrait-multimethod (MTMM) model is proposed to estimate random and systematic measurement error in categorical survey questions while making fewer assumptions than have been made so far in such evaluations, allowing for possible extreme response behavior and other nonmonotone effects. The method is a combination of the MTMM research design of Campbell and Fiske (1959), the basic response model for survey questions of Saris and Andrews (1991), and the latent class factor model of Vermunt and Magidson (2004, pp. 227-230). The latent class MTMM model thus combines an existing design, model, and method to allow for the estimation of the degree to and manner in which survey questions are affected by systematic measurement error. Starting from a general form of the response function for a survey question, we present the MTMM experimental approach to identification of the response function's parameters. A "trait-method biplot" is introduced as a means of interpreting the estimates of systematic measurement error, whereas the quality of the questions can be evaluated by item information curves and the item information function. An experiment from the European Social Survey is analyzed and the results are discussed, yielding valuable insights into the functioning of a set of example questions on the role of women in society in 2 countries.

  11. Latent common genetic components of obesity traits

    PubMed Central

    Harders, R; Luke, A; Zhu, X; Cooper, RS

    2008-01-01

    Background Obesity is rapidly becoming a global epidemic. Unlike many complex human diseases, obesity is defined not just by a single trait or phenotype, but jointly by measures of anthropometry and metabolic status. Methods We applied maximum likelihood factor analysis to identify common latent factors underlying observed covariance in multiple obesity-related measures. Both the genetic components and the mode of inheritance of the common factors were evaluated. A total of 1775 participants from 590 families for whom measures on obesity-related traits were available were included in this study. Results The average age of participants was 37 years, 39% of the participants were obese (body mass index ≥ 30.0 kg/m2) and 26% were overweight (body mass index 25.0 - 29.9 kg/m2). Two latent common factors jointly accounting for over 99% of the correlations among obesity-related traits were identified. Complex segregation analysis of the age and sex-adjusted latent factors provide evidence for a Mendelian mode of inheritance of major genetic effect with heritability estimates of 40.4% and 47.5% for the first and second factors, respectively. Conclusions These findings provide a support for multivariate-based approach for investigating pleiotropic effects on obesity-related traits which can be applied in both genetic linkage and association mapping. PMID:18936762

  12. Factors associated with latent fingerprint exclusion determinations.

    PubMed

    Ulery, Bradford T; Hicklin, R Austin; Roberts, Maria Antonia; Buscaglia, JoAnn

    2017-02-22

    Exclusion is the determination by a latent print examiner that two friction ridge impressions did not originate from the same source. The concept and terminology of exclusion vary among agencies. Much of the literature on latent print examination focuses on individualization, and much less attention has been paid to exclusion. This experimental study assesses the associations between a variety of factors and exclusion determinations. Although erroneous exclusions are more likely to occur on some images and for some examiners, they were widely distributed among images and examiners. Measurable factors found to be associated with exclusion rates include the quality of the latent, value determinations, analysis minutia count, comparison difficulty, and the presence of cores or deltas. An understanding of these associations will help explain the circumstances under which errors are more likely to occur and when determinations are less likely to be reproduced by other examiners; the results should also lead to improved effectiveness and efficiency of training and casework quality assurance. This research is intended to assist examiners in improving the examination process and provide information to the broader community regarding the accuracy, reliability, and implications of exclusion decisions.

  13. Visualization of latent fingerprint corrosion of metallic surfaces.

    PubMed

    Bond, John W

    2008-07-01

    Chemical reactions between latent fingerprints and a variety of metal surfaces are investigated by heating the metal up to temperatures of approximately 600 degrees C after deposition of the fingerprint. Ionic salts present in the fingerprint residue corrode the metal surface to produce an image of the fingerprint that is both durable and resistant to cleaning of the metal. The degree of fingerprint enhancement appears independent of the elapsed time between deposition and heating but is very dependent on both the composition of the metal and the level of salt secretion by the fingerprint donor. Results are presented that show practical applications for the enhancement to fingerprints deposited in arson crime scenes, contaminated by spray painting, or deposited on brass cartridge cases prior to discharge. The corrosion of the metal surface is further exploited by the demonstration of a novel technique for fingerprint enhancement based on the electrostatic charging of the metal and then the preferential adherence of a metallic powder to the corroded part of the metal surface.

  14. Desiccant Humidity Control System Using Waste Heat of Water Source Heat Pump

    NASA Astrophysics Data System (ADS)

    Wada, Kazuki; Mashimo, Kouichi; Takahashi, Mikio; Tanaka, Kitoshi; Toya, Saburo; Tateyama, Ryotaro; Miyamoto, Kazuhiro; Yamaguchi, Masahiro

    The authors hope to develop an air-conditioning system that processes the latent heat load and the sensible heat load separately. This would enable the efficiency of the chilling unit to be improved because the temperature of the chilled water used for cooling would be higher than normal. However, if lukewarm water is used, there is insufficient cooling and dehumidification. Therefore, a dehumidifier such as a desiccant air-conditioning system is needed. Using the waste heat generated when the desiccant air-conditioning system is in operation increases efficiency. The authors are developing a prototype desiccant humidity control system that makes use of the waste heat generated by a water source heat pump. This paper describes the results of an experiment that was conducted for this prototype based on the assumption that it would be installed in an office building. The dehumidification performance achieved was sufficient to process the indoor latent heat load. The prototype was able to adjust the indoor relative humidity from 40% to 60% under conditions in which the indoor latent heat load varied. Humidification without the use of water was possible even in the absence of an indoor latent heat load when the outdoor absolute humidity was 3.5 g/kg' or more.

  15. Microwave selective thermal development of latent fingerprints on porous surfaces: potentialities of the method and preliminary experimental results.

    PubMed

    Rosa, Roberto; Veronesi, Paolo; Leonelli, Cristina

    2013-09-01

    The thermal development of latent fingerprints on paper surfaces is a simple, safe, and chemicals-free method, based on the faster heating of the substrate underlying the print residue. Microwave heating is proposed for the first time for the development of latent fingerprints on cellulose-based substrate, in order to add to the thermal development mechanism the further characteristic of being able to heat the fingerprint residues to a different extent with respect to the substrate, due to the intrinsic difference in their dielectric properties. Numerical simulation was performed to confirm and highlight the selectivity of microwaves, and preliminary experimental results point out the great potentialities of this technique, which allowed developing both latent sebaceous-rich and latent eccrine-rich fingerprints on different porous surfaces, in less than 30 sec time with an applied output power of 500 W. Microwaves demonstrated more effectiveness in the development of eccrine-rich residues, aged up to 12 weeks.

  16. Conversion from latent to symptomatic Sheehan's syndrome by pegylated interferon therapy for chronic hepatitis C.

    PubMed

    Kanda, Keitaro; Kayahara, Takahisa; Seno, Hiroshi; Yamashita, Yukitaka; Chiba, Tsutomu

    2008-01-01

    A 58-year-old woman with chronic hepatitis C was admitted to our hospital to receive interferon (IFN) therapy. Twenty years earlier she had received blood transfusion because of obstetric hemorrhage. Blood test showed mild hypothyroidism and a relatively elevated eosinophil count. Therapy with pegylated IFNalpha-2a was started, and two days later she complained of nausea and severe malaise. Blood test showed hyponatremia, and plasma prolactin, growth hormone and cortisol levels were all decreased. A simultaneous administration test of lutenizing hormone releasing-, corticotrophin releasing-, growth hormone releasing- and thyrotropin releasing-hormones revealed that only adrenocorticotropic hormone was responsive. Magnetic resonance imaging showed atrophy of anterior lobe of pituitary gland. We diagnosed that IFN therapy disclosed latent Sheehan's syndrome due to previous obstetric hemorrhage. Following supplementation of thyroid and adrenal cortical hormones, we were able to complete IFN therapy. Thus, before IFN therapy for woman patients it is important to suspect latent Sheehan's syndrome when the patient had a history of obstetric hemorrhage.

  17. Understanding latent tuberculosis: the key to improved diagnostic and novel treatment strategies

    PubMed Central

    Esmail, Hanif; Barry, Clifton E; Wilkinson, Robert J

    2012-01-01

    Treatment of latent tuberculosis (LTBI) is a vital component of tuberculosis elimination but is not efficiently implemented with available diagnostics and therapeutics. The tuberculin skin test and interferon gamma release assays can inform that infection has occurred but do not prove that it persists. Treatment of LTBI with isoniazid targets actively replicating bacilli but not non-replicating populations, prolonging treatment duration. Developing more predictive diagnostic tests and treatments of shorter duration requires a greater understanding of the biology of latent tuberculosis, from both host and bacillary perspectives. In this article we discuss the basis of current diagnosis and treatment of LTBI and review recent developments in understanding the biology of latency that may enable future improved diagnostic and treatment strategies. PMID:22198298

  18. Rifapentine, Moxifloxacin, or DNA Vaccine Improves Treatment of Latent Tuberculosis in a Mouse Model

    PubMed Central

    Nuermberger, Eric; Tyagi, Sandeep; Williams, Kathy N.; Rosenthal, Ian; Bishai, William R.; Grosset, Jacques H.

    2005-01-01

    Rationale: Priorities for developing improved regimens for treatment of latent tuberculosis (TB) infection include (1) developing shorter and/or more intermittently administered regimens that are easier to supervise and (2) developing and evaluating regimens that are active against multidrug-resistant organisms. Objectives and Methods: By using a previously validated murine model that involves immunizing mice with Mycobacterium bovis bacillus Calmette-Guérin to augment host immunity before infection with virulent Mycobacterium tuberculosis, we evaluated new treatment regimens including rifapentine and moxifloxacin, and assessed the potential of the Mycobacterium leprae heat shock protein-65 DNA vaccine to augment the activity of moxifloxacin. Measurements: Quantitative spleen colony-forming unit counts, and the proportion of mice with culture-positive relapse after treatment, were determined. Main Results: Three-month, once-weekly regimens of rifapentine combined with either isoniazid or moxifloxacin were as active as daily isoniazid for 6–9 mo. Six-month daily combinations of moxifloxacin with pyrazinamide, ethionamide, or ethambutol were more active than pyrazinamide plus ethambutol, a regimen recommended for latent TB infection after exposure to multidrug-resistant TB. The combination of moxifloxacin with the experimental nitroimidazopyran PA-824 was especially active. Finally, the heat shock protein-65 DNA vaccine had no effect on colony-forming unit counts when given alone, but augmented the bactericidal activity of moxifloxacin. Conclusions: Together, these findings suggest that rifapentine, moxifloxacin, and, perhaps, therapeutic DNA vaccination have the potential to improve on the current treatment of latent TB infection. PMID:16151038

  19. Testing and Failure Mechanisms of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.; Hawkins-Reynolds, Ebony

    2010-01-01

    Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as Low Earth Orbit (LEO) and Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents the results of testing that occurred from March through September of 2010 and builds on testing that occurred during the previous year.

  20. Development, Testing, and Failure Mechanisms of a Replicative Ice Phase Change Material Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Hansen, Scott; Stephan, Ryan A.

    2009-01-01

    Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as Low Earth Orbit (LEO) and Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. Wax PCM units have been baselined for the Orion thermal control system and also provide risk mitigation for the Altair Lander. However, the use of water as a PCM has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. An ice PCM heat exchanger that replicates the thermal energy storage capacity of an existing wax PCM unit was fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion are investigated. This paper presents the results to date of this investigation.

  1. Development, Testing, and Failure Mechanisms of a Replicative Ice Phase Change Material Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Hansen, Scott; Stephan, Ryan A.

    2010-01-01

    Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as Low Earth Orbit (LEO) and Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM's have over evaporators in this scenario is that they do not use a consumable. Wax PCM units have been baselined for the Orion thermal control system and also provide risk mitigation for the Altair Lander. However, the use of water as a PCM has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. An ice PCM heat exchanger that replicates the thermal energy storage capacity of an existing wax PCM unit was fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion are investigated. This paper presents the results to date of this investigation. Nomenclature

  2. Testing and Failure Mechanisms of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.; Hawkins-Reynolds, Ebony

    2011-01-01

    Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as specific spacecraft orientations in Low Earth Orbit (LEO) and low beta angle Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. The use of water as a PCM rather than the more tradition