WorldWideScience

Sample records for lw radiative forcing

  1. Spinning projectile's attitude measurement with LW infrared radiation under sea-sky background

    Science.gov (United States)

    Xu, Miaomiao; Bu, Xiongzhu; Yu, Jing; He, Zilu

    2018-05-01

    With the further development of infrared radiation research in sea-sky background and the requirement of spinning projectile's attitude measurement, the sea-sky infrared radiation field is used to carry out spinning projectile's attitude angle instead of inertial sensors. Firstly, the generation mechanism of sea-sky infrared radiation is analysed. The mathematical model of sea-sky infrared radiation is deduced in LW (long wave) infrared 8 ∼ 14 μm band by calculating the sea surface and sky infrared radiation. Secondly, according to the movement characteristics of spinning projectile, the attitude measurement model of infrared sensors on projectile's three axis is established. And the feasibility of the model is analysed by simulation. Finally, the projectile's attitude calculation algorithm is designed to improve the attitude angle estimation accuracy. The results of semi-physical experiments show that the segmented interactive algorithm estimation error of pitch and roll angle is within ±1.5°. The attitude measurement method is effective and feasible, and provides accurate measurement basis for the guidance of spinning projectile.

  2. Improving Estimates of Cloud Radiative Forcing over Greenland

    Science.gov (United States)

    Wang, W.; Zender, C. S.

    2014-12-01

    Multiple driving mechanisms conspire to increase melt extent and extreme melt events frequency in the Arctic: changing heat transport, shortwave radiation (SW), and longwave radiation (LW). Cloud Radiative Forcing (CRF) of Greenland's surface is amplified by a dry atmosphere and by albedo feedback, making its contribution to surface melt even more variable in time and space. Unfortunately accurate cloud observations and thus CRF estimates are hindered by Greenland's remoteness, harsh conditions, and low contrast between surface and cloud reflectance. In this study, cloud observations from satellites and reanalyses are ingested into and evaluated within a column radiative transfer model. An improved CRF dataset is obtained by correcting systematic discrepancies derived from sensitivity experiments. First, we compare the surface radiation budgets from the Column Radiation Model (CRM) driven by different cloud datasets, with surface observations from Greenland Climate Network (GC-Net). In clear skies, CRM-estimated surface radiation driven by water vapor profiles from both AIRS and MODIS during May-Sept 2010-2012 are similar, stable, and reliable. For example, although AIRS water vapor path exceeds MODIS by 1.4 kg/m2 on a daily average, the overall absolute difference in downwelling SW is CRM estimates are within 20 W/m2 range of GC-Net downwelling SW. After calibrating CRM in clear skies, the remaining differences between CRM and observed surface radiation are primarily attributable to differences in cloud observations. We estimate CRF using cloud products from MODIS and from MERRA. The SW radiative forcing of thin clouds is mainly controlled by cloud water path (CWP). As CWP increases from near 0 to 200 g/m2, the net surface SW drops from over 100 W/m2 to 30 W/m2 almost linearly, beyond which it becomes relatively insensitive to CWP. The LW is dominated by cloud height. For clouds at all altitudes, the lower the clouds, the greater the LW forcing. By applying

  3. Sensitivity of surface temperature to radiative forcing by contrail cirrus in a radiative-mixing model

    Directory of Open Access Journals (Sweden)

    U. Schumann

    2017-11-01

    Full Text Available Earth's surface temperature sensitivity to radiative forcing (RF by contrail cirrus and the related RF efficacy relative to CO2 are investigated in a one-dimensional idealized model of the atmosphere. The model includes energy transport by shortwave (SW and longwave (LW radiation and by mixing in an otherwise fixed reference atmosphere (no other feedbacks. Mixing includes convective adjustment and turbulent diffusion, where the latter is related to the vertical component of mixing by large-scale eddies. The conceptual study shows that the surface temperature sensitivity to given contrail RF depends strongly on the timescales of energy transport by mixing and radiation. The timescales are derived for steady layered heating (ghost forcing and for a transient contrail cirrus case. The radiative timescales are shortest at the surface and shorter in the troposphere than in the mid-stratosphere. Without mixing, a large part of the energy induced into the upper troposphere by radiation due to contrails or similar disturbances gets lost to space before it can contribute to surface warming. Because of the different radiative forcing at the surface and at top of atmosphere (TOA and different radiative heating rate profiles in the troposphere, the local surface temperature sensitivity to stratosphere-adjusted RF is larger for SW than for LW contrail forcing. Without mixing, the surface energy budget is more important for surface warming than the TOA budget. Hence, surface warming by contrails is smaller than suggested by the net RF at TOA. For zero mixing, cooling by contrails cannot be excluded. This may in part explain low efficacy values for contrails found in previous global circulation model studies. Possible implications of this study are discussed. Since the results of this study are model dependent, they should be tested with a comprehensive climate model in the future.

  4. Intercomparison of radiative forcing calculations of stratospheric water vapour and contrails

    Energy Technology Data Exchange (ETDEWEB)

    Myhre, Gunnar [Dept. of Geosciences, Univ. of Oslo (Norway); Center for International Climate and Environmental Research-Oslo (CICERO), Oslo (Norway); Kvalevaag, Maria [Dept. of Geosciences, Univ. of Oslo (Norway); Raedel, Gaby; Cook, Jolene; Shine, Keith P. [Dept. of Meteorology, Univ. of Reading (United Kingdom); Clark, Hannah [CNRM/GAME Meteo France, Toulouse (France); Lab. d' Aerologie, Univ. de Toulouse (France); Karcher, Fernand [CNRM/GAME Meteo France, Toulouse (France); Markowicz, Krzysztof; Kardas, Aleksandra; Wolkenberg, Paulina [Inst. of Geophysics, Univ. of Warsaw (Poland); Balkanski, Yves [LSCE/IPSL, Lab. CEA-CNRS-UVSQ (France); Ponater, Michael [Deutsches Zentrum fuer Luft und Raumfahrt (DLR), Inst. fuer Physik der Atmosphaere, Oberpfaffenhofen (Germany); Forster, Piers; Rap, Alexandru [School of Earth and Environment, Univ. of Leeds (United Kingdom); Leon, Ruben Rodriguez de [Manchester Metropolitan Univ. (United Kingdom)

    2009-12-15

    Seven groups have participated in an intercomparison study of calculations of radiative forcing (RF) due to stratospheric water vapour (SWV) and contrails. a combination of detailed radiative transfer schemes and codes for global-scale calculations have been used, as well as a combination of idealized simulations and more realistic global-scale changes in stratospheric water vapour and contrails. Detailed line-by-line codes agree within about 15% for longwave (LW) and shortwave (SW) RF, except in one case where the difference is 30%. Since the LW and SW RF due to contrails and SWV changes are of opposite sign, the differences between the models seen in the individual LW and SW components can be either compensated or strengthened in the net RF. and thus in relative terms uncertainties are much larger for the net RF. Some of the models used for global-scale simulations of changes in SWV and contrails differ substantially in RF from the more detailed radiative transfer schemes. For the global-scale calculations we use a method of weighting the results to calculate a best estimate based on their performance compared to the more detailed radiative transfer schemes in the idealized simulations. (orig.)

  5. Factors Affecting Aerosol Radiative Forcing

    Science.gov (United States)

    Wang, J.; Lin, J.; Ni, R.

    2016-12-01

    Rapid industrial and economic growth has meant large amount of aerosols in the atmosphere with strong radiative forcing (RF) upon the climate system. Over parts of the globe, the negative forcing of aerosols has overcompensated for the positive forcing of greenhouse gases. Aerosol RF is determined by emissions and various chemical-transport-radiative processes in the atmosphere, a multi-factor problem whose individual contributors have not been well quantified. In this study, we analyze the major factors affecting RF of secondary inorganic aerosols (SIOAs, including sulfate, nitrate and ammonium), primary organic aerosol (POA), and black carbon (BC). We analyze the RFof aerosols produced by 11 major regions across the globe, including but not limited to East Asia, Southeast Asia, South Asia, North America, and Western Europe. Factors analyzed include population size, per capita gross domestic production (GDP), emission intensity (i.e., emissionsper unit GDP), chemical efficiency (i.e., mass per unit emissions) and radiative efficiency (i.e., RF per unit mass). We find that among the 11 regions, East Asia produces the largest emissions and aerosol RF, due to relatively high emission intensity and a tremendous population size.South Asia produce the second largest RF of SIOA and BC and the highest RF of POA, in part due to its highest chemical efficiency among all regions. Although Southeast Asia also has large emissions,its aerosol RF is alleviated by its lowest chemical efficiency.The chemical efficiency and radiative efficiency of BC produced by the Middle East-North Africa are the highest across the regions, whereas its RF is loweredbyasmall per capita GDP.Both North America and Western Europe have low emission intensity, compensating for the effects on RF of large population sizes and per capita GDP. There has been a momentum to transfer industries to Southeast Asia and South Asia, and such transition is expected to continue in the coming years. The resulting

  6. A Climatology of Midlatitude Continental Clouds from the ARM SGP Site. Part II; Cloud Fraction and Surface Radiative Forcing

    Science.gov (United States)

    Xi, B.; Minnis, P.

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Central Facility (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative forcing between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layered low (0-3 km), middle (3-6 km), and high clouds (more than 6 km) using ARM SCG ground-based paired lidar-radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements with uncertainties of approximately 10 Wm(exp -2). The annual averages of total, and single-layered low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Both total and low cloud amounts peak during January and February and reach a minimum during July and August, high clouds occur more frequently than other types of clouds with a peak in summer. The average annual downwelling surface SW fluxes for total and low clouds (151 and 138 Wm(exp-2), respectively) are less than those under middle and high clouds (188 and 201 Wm(exp -2), respectively), but the downwelling LW fluxes (349 and 356 Wm(exp -2)) underneath total and low clouds are greater than those from middle and high clouds (337 and 333 Wm(exp -2)). Low clouds produce the largest LW warming (55 Wm(exp -2) and SW cooling (-91 Wm(exp -2)) effects with maximum and minimum absolute values in spring and summer, respectively. High clouds have the smallest LW warming (17 Wm(exp -2)) and SW cooling (-37 Wm(exp -2)) effects at the surface. All-sky SW CRF decreases and LW CRF increases with increasing cloud fraction with mean slopes of -0.984 and 0.616 Wm(exp -2)%(exp -1), respectively. Over the entire diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW flux. The calculated CRFs do not appear to be significantly

  7. Spatially Refined Aerosol Direct Radiative Forcing Efficiencies

    Science.gov (United States)

    Global aerosol direct radiative forcing (DRF) is an important metric for assessing potential climate impacts of future emissions changes. However, the radiative consequences of emissions perturbations are not readily quantified nor well understood at the level of detail necessary...

  8. Acoustic radiation force control: Pulsating spherical carriers.

    Science.gov (United States)

    Rajabi, Majid; Mojahed, Alireza

    2018-02-01

    The interaction between harmonic plane progressive acoustic beams and a pulsating spherical radiator is studied. The acoustic radiation force function exerted on the spherical body is derived as a function of the incident wave pressure and the monopole vibration characteristics (i.e., amplitude and phase) of the body. Two distinct strategies are presented in order to alter the radiation force effects (i.e., pushing and pulling states) by changing its magnitude and direction. In the first strategy, an incident wave field with known amplitude and phase is considered. It is analytically shown that the zero- radiation force state (i.e., radiation force function cancellation) is achievable for specific pulsation characteristics belong to a frequency-dependent straight line equation in the plane of real-imaginary components (i.e., Nyquist Plane) of prescribed surface displacement. It is illustrated that these characteristic lines divide the mentioned displacement plane into two regions of positive (i.e., pushing) and negative (i.e., pulling) radiation forces. In the second strategy, the zero, negative and positive states of radiation force are obtained through adjusting the incident wave field characteristics (i.e., amplitude and phase) which insonifies the radiator with prescribed pulsation characteristics. It is proved that zero radiation force state occurs for incident wave pressure characteristics belong to specific frequency-dependent circles in Nyquist plane of incident wave pressure. These characteristic circles divide the Nyquist plane into two distinct regions corresponding to positive (out of circles) and negative (in the circles) values of radiation force function. It is analytically shown that the maximum amplitude of negative radiation force is exactly equal to the amplitude of the (positive) radiation force exerted upon the sphere in the passive state, by the same incident field. The developed concepts are much more deepened by considering the required

  9. On the forces acting on radiating charge

    International Nuclear Information System (INIS)

    Khachatrian, B.V.

    2001-01-01

    It is shown that the force acting on a radiating charge is stipulated by two reasons- owing to exchange of a momentum between the radiating charge and electromagnetic field of radiation, and also between the charge and field accompanying the charge. 7 refs

  10. Micromechanical Resonator Driven by Radiation Pressure Force.

    Science.gov (United States)

    Boales, Joseph A; Mateen, Farrukh; Mohanty, Pritiraj

    2017-11-22

    Radiation pressure exerted by light on any surface is the pressure generated by the momentum of impinging photons. The associated force - fundamentally, a quantum mechanical aspect of light - is usually too small to be useful, except in large-scale problems in astronomy and astrodynamics. In atomic and molecular optics, radiation pressure can be used to trap or cool atoms and ions. Use of radiation pressure on larger objects such as micromechanical resonators has been so far limited to its coupling to an acoustic mode, sideband cooling, or levitation of microscopic objects. In this Letter, we demonstrate direct actuation of a radio-frequency micromechanical plate-type resonator by the radiation pressure force generated by a standard laser diode at room temperature. Using two independent methods, the magnitude of the resonator's response to forcing by radiation pressure is found to be proportional to the intensity of the incident light.

  11. Tropospheric radiative forcing of CH4

    International Nuclear Information System (INIS)

    Grossman, A.S.; Grant, K.E.

    1994-04-01

    We have evaluated the tropospheric radiative forcing of CH 4 in the 0-3000 cm -1 wavenumber range and compared this with prior published calculations. The atmospheric test cases involved perturbed methane scenarios in both a McClatchey mid latitude, summer, clear sky approximation, model atmosphere, as well as a globally and seasonally averaged model atmosphere containing a representative cloud distribution. The scenarios involved pure CH 4 radiative forcing and CH 4 plus a mixture of H 2 O, CO 2 , O 3 , and N 2 O. The IR radiative forcing was calculated using a correlated k-distribution transmission model. The major purposes of this paper are to first, use the correlated k-distribution model to calculate the tropospheric radiative forcing for CH 4 , as the only radiatively active gas, and in a mixture with H 2 O, CO 2 , O 3 , and N 2 O, for a McClatchey mid-latitude summer, clear-sky model atmosphere, and to compare the results to those obtained in the studies mentioned above. Second, we will calculate the tropospheric methane forcing in a globally and annually averaged atmosphere with and without a representative cloud distribution in order to validate the conjecture given in IPCC (1990) that the inclusion of clouds in the forcing calculations results in forcing values which are approximately 20 percent less than those obtained using clear sky approximations

  12. Observations of black carbon aerosols characteristics over an urban environment: Radiative forcing and related implications.

    Science.gov (United States)

    Bibi, Samina; Alam, Khan; Chishtie, Farrukh; Bibi, Humera; Rahman, Said

    2017-12-15

    With observations of black carbon (BC) aerosol concentrations, optical and radiative properties were obtained over the urban city of Karachi during the period of March 2006-December 2008. BC concentrations were continuously measured using an Aethalometer, while optical and radiative properties were estimated through the Optical Properties of Aerosols and Clouds (OPAC) and Santa Barbra DISORT Atmospheric Radiative Transfer (SBDART) models, respectively. For the study period, the measured BC concentrations were higher during January, February and November, while lower during May, June, July and August. A maximum peak value was observed during January 2007 while the minimum value was observed during June 2006. The Short Wave (SW) BC Aerosol Radiative Forcing (ARF) both at Top of the Atmosphere (ToA) and within ATMOSphere (ATMOS) were positive during all the months, whereas negative SW BC ARF was found at the SurFaCe (SFC). Overall, SW BC ARF was higher during January, February and November, while relatively lower ARF was found during May, June, July and August. Conversely, the Long Wave (LW) BC ARF at ToA and SFC remained positive, whereas within ATMOS it shifted towards positive values (heating effect) during June-August. Finally, the net (SW+LW) BC ARF were found to be positive at ToA and in ATMOS, while negative at SFC. Moreover, a systematic increase in Atmospheric Heating Rate (AHR) was found during October to January. Additionally, we found highest correlation between Absorption Aerosol Optical Depth (AOD abs ) and SW BC ARF within ATMOS followed by SFC and ToA. Overall, the contribution of BC to the total ARF was found to greater than 84% for the whole observational period while contributing up to 93% during January 2007. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Radiative Forcing Over Ocean by Ship Wakes

    Science.gov (United States)

    Gatebe, Charles K.; Wilcox, E.; Poudyal, R.; Wang, J.

    2011-01-01

    Changes in surface albedo represent one of the main forcing agents that can counteract, to some extent, the positive forcing from increasing greenhouse gas concentrations. Here, we report on enhanced ocean reflectance from ship wakes over the Pacific Ocean near the California coast, where we determined, based on airborne radiation measurements that ship wakes can increase reflected sunlight by more than 100%. We assessed the importance of this increase to climate forcing, where we estimated the global radiative forcing of ship wakes to be -0.00014 plus or minus 53% Watts per square meter assuming a global distribution of 32331 ships of size of greater than or equal to 100000 gross tonnage. The forcing is smaller than the forcing of aircraft contrails (-0.007 to +0.02 Watts per square meter), but considering that the global shipping fleet has rapidly grown in the last five decades and this trend is likely to continue because of the need of more inter-continental transportation as a result of economic globalization, we argue that the radiative forcing of wakes is expected to be increasingly important especially in harbors and coastal regions.

  14. Final Technical Report 09 LW 112

    Energy Technology Data Exchange (ETDEWEB)

    Lenhoff, R J

    2010-11-28

    Since the development of new antibiotics is out-paced by the emergence of bacterial resistance to existing antibiotics, it is crucial to understand the genetic mechanisms underlying resistance existing antibiotics. At the center of this mystery is a poorly understood phenomenon, heteroresistance: the coexistence of multiple subpopulations with varying degrees of antibiotic resistance. A better understanding of the fundamental basis of heteroresistance could result in sorely needed breakthroughs in treatment options. This project proposed to leverage a novel microfluidic (microchemostat) technology to probe the heteroresistance phenomenon in bacteria, with the aim of restoring the efficacy of existing {beta}-lactam antibiotics. The clinically important bacteria Methicillin Resistant S. aureus (MRSA) was used as the test case of bacteria that exhibits antibiotic heteroresistance. MRSA is difficult to treat because it is resistant to all {beta}-lactam antibiotics, as well as other classes of antimicrobials. Whereas {beta}-lactams such as methicillin and oxacillin are the preferred antibiotics to treat S. aureus infections due to their efficacy and low side effects, accurate determination and use of oxacillin/methicillin dosage is hampered by heteroresistance. In fact, invasive MRSA infections now account for about 95,000 deaths per year, a number that exceeds the deaths due to either influenza or HIV (12). In some MRSA strains, two subpopulations of cells may coexist: both populations carry the mecA gene that confers resistance, but mecA is differentially expressed so that only a small number of cells are observed during in vitro testing. Why this occurs is not understood. Prior experiments have sought to explain this phenomenon with conflicting results, with technology being the primary barrier to test the system sufficiently. This is the final report on work accomplished under the Lab-wide LDRD project 09-LW-112. This project was awarded to Frederick Balagadde who

  15. Debate about anthropogenic radiative forcing

    International Nuclear Information System (INIS)

    Anon

    2001-01-01

    A recent paper by James Hansen and colleagues at the NASA Goddard Institute for Space Studies in the Proceedings of the National Academy of Science has been widely interpreted in the media, incorrectly as it turned out, that Hansen has changed his earlier views and concerns about climate change, that he no longer considers fossil fuel combustion as the primary concern in international efforts to reduce the risk of climate change. Some have gone so far as to cite the Hansen paper as further evidence that the ratification and implementation of the Kyoto protocols would be inappropriate. Despite various rebuttals, the confusion about Hansen's conclusion continues to persist. This analysis attempts to summarize the the key points made by Hansen and his colleagues, and to place their comments in the general context of the international science community, and to assess the real policy implications. The gist of the comments by Hansen et al. is that future growth rates in CO 2 concentrations may be weaker than some 'business as usual' scenarios suggest. If so, efforts to control CO 2 growth would be easier than presently assumed. The slower growth appears to be due to larger uptake of emitted CO 2 into the oceans and terrestrial biosphere. However, Hansen et al. also acknowledge that this enhanced sink may be temporary, and have in fact been increasing in recent years, and therefore to maintain a continued slow growth rate for CO 2 concentrations, fossil fuel emissions have to become lower than currently projected in 'business as usual' scenarios. The alternative mitigation scenario proposed by Hansen et al. promotes concentrated efforts to reduce emissions of non-CO 2 greenhouse gases. Hansen and co-workers suggest that reduction of non C O 2 emissions would probably allow forcing due to CO 2 emissions to increase a further 1 W/sq m by 2050 without compromising efforts to avoid dangerous climate change. These reviewers believe that the key feature of the Hansen approach

  16. Radiative forcing calculations for CH3Cl

    International Nuclear Information System (INIS)

    Grossman, A.S.; Grant, K.E.; Wuebbles, D.J.

    1994-06-01

    Methyl chloride, CH 3 Cl, is the major natural source of chlorine to the stratosphere. The production of CH 3 Cl is dominated by biological sources from the oceans and biomass burning. Production has a seasonal cycle which couples with the short lifetime of tropospheric CH 3 Cl to produce nonuniform global mixing. As an absorber of infrared radiation, CH 3 Cl is of interest for its potential affect on the tropospheric energy balance as well as for its chemical interactions. In this study, we estimate the radiative forcing and global warming potential (GWP) of CH 3 Cl. Our calculations use an infrared radiative transfer model based on the correlated k-distribution algorithm for band absorption. Global and annual average vertical profiles of temperature and trace gas concentration were assumed. The effects of clouds are modeled using three layers of global and annual average cloud optical properties. A radiative forcing value of 0.0053 W/m 2 ppbv was obtained for CH 3 Cl and is approximately linear in the background abundance. This value is about 2 percent of the forcing of CFC-11 and about 300 times the forcing of CO 2 , on a per molecule basis. The radiative forcing calculation for CH 3 Cl is used to estimate the global warming potential (GWP) of CH 3 Cl. The results give GWPs for CH 3 Cl of the order of 25 at a time of 20 years(CO 2 = 1). This result indicates that CH 3 Cl has the potential to be a major greenhouse gas if significant human related emissions were introduced into the atmosphere

  17. Resonant acoustic radiation force optical coherence elastography

    OpenAIRE

    Qi, Wenjuan; Li, Rui; Ma, Teng; Li, Jiawen; Kirk Shung, K.; Zhou, Qifa; Chen, Zhongping

    2013-01-01

    We report on a resonant acoustic radiation force optical coherence elastography (ARF-OCE) technique that uses mechanical resonant frequency to characterize and identify tissues of different types. The linear dependency of the resonant frequency on the square root of Young's modulus was validated on silicone phantoms. Both the frequency response spectrum and the 3D imaging results from the agar phantoms with hard inclusions confirmed the feasibility of deploying the resonant frequency as a mec...

  18. Radiative forcing calculations for CH3Br

    International Nuclear Information System (INIS)

    Grossman, A.S.; Blass, W.E.; Wuebbles, D.J.

    1995-06-01

    Methyl Bromide, CH 3 Br, is the major organobromine species in the lower atmosphere and is a primary source of bromine in the stratosphere. It has a lifetime of 1.3 years. The IR methyl bromide spectra in the atmospheric window region, 7--13μ, was determined using a well tested Coriolis resonance and ell-doubling (and ell-resonance) computational system. A radiative forcing value of 0.00493 W/m 2 /ppbv was obtained for CH 3 Br and is approximately linear in the background abundance. This value is about 2 percent of the forcing of CFC-11 and about 278 times the forcing of C0 2 , on a per molecule basis. The radiative forcing calculation is used to estimate the global warming potential (GWP) of CH 3 Br. The results give GWPs for CH 3 Br of the order of 13 for an integration period of 20 years and 4 for an integration period of 100 years (assuming C0 2 = 1, following IPCC [1994]). While CH 3 Br has a GWP which is approximately 25 percent of the GWP of CH 4 , the current emission rates are too low to cause serious atmospheric greenhouse heating effects at this time

  19. Dust aerosol properties and radiative forcing observed in spring during 2001-2014 over urban Beijing, China.

    Science.gov (United States)

    Yu, Xingna; Lü, Rui; Kumar, K Raghavendra; Ma, Jia; Zhang, Qiuju; Jiang, Yilun; Kang, Na; Yang, Suying; Wang, Jing; Li, Mei

    2016-08-01

    The ground-based characteristics (optical and radiative properties) of dust aerosols measured during the springtime between 2001 and 2014 were investigated over urban Beijing, China. The seasonal averaged aerosol optical depth (AOD) during spring of 2001-2014 was about 0.78 at 440 nm. During dust days, higher AOD occurred associated with lower Ångström exponent (AE). The mean AE440-870 in the springtime was about 1.0, indicating dominance of fine particles over the region. The back-trajectory analysis revealed that the dust was transported from the deserts of Inner Mongolia and Mongolia arid regions to Beijing. The aerosol volume size distribution showed a bimodal distribution pattern, with its highest peak observed in coarse mode for all episodes (especially for dust days with increased volume concentration). The single scattering albedo (SSA) increased with wavelength on dust days, indicating the presence of more scattering particles. Furthermore, the complex parts (real and imaginary) of refractive index showed distinct characteristics with lower imaginary values (also scattering) on dust days. The shortwave (SW; 0.2-4.0 μm) and longwave (LW; 4-100 μm) aerosol radiative forcing (ARF) values were computed from the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model both at the top of atmosphere (TOA) and the bottom of atmosphere (BOA) during dust and non-dust (dust free) days, and the corresponding heating rates and forcing efficiencies were also estimated. The SW (LW) ARF, therefore, produced significant cooling (warming) effects at both the TOA and the BOA over Beijing.

  20. A modeling perspective on cloud radiative forcing

    International Nuclear Information System (INIS)

    Potter, G.L.; Corsetti, L.; Slingo, J.M.

    1993-02-01

    Radiation fields from a perpetual July integration of a T106 version of the ECM-WF operational model are used to identify the most appropriate way to diagnose cloud radiative forcing in a general circulation model, for the purposes of intercomparison between models. Differences between the Methods I and II of Cess and Potter (1987) and a variant method are addressed. Method I is shown to be the least robust of all methods, due to the potential uncertainties related to persistent cloudiness, length of the sampling period and biases in retrieved clear-sky quantities due to insufficient sampling of the diurnal cycle. Method II is proposed as an unambiguous way to produce consistent radiative diagnostics for intercomparing model results. The impact of the three methods on the derived sensitivities and cloud feedbacks following an imposed change in sea surface temperature is discussed. The sensitivity of the results to horizontal resolution is considered by using the diagnostics from parallel integrations with T21 version of the model

  1. Radiative forcing for changes in tropospheric O3

    International Nuclear Information System (INIS)

    Grossman, A.S.; Wuebbles, D.J.; Grant, K.E.

    1994-06-01

    We have evaluated the radiative forcing for assumed changes in tropospheric O 3 in the 500-1650 cm -1 wavenumber range. The radiative forcing calculations were performed as a function of latitude as well as for a globally and seasonally averaged model atmosphere, both in a clear sky approximation and in a model containing a representative cloud distribution. The scenarios involved radiative forcing calculations for O 3 at normal atmospheric abundance and at a tropospheric abundance depleted by 25 ppbv, at each altitude, for all northern hemisphere latitudes. Normal abundances of H 2 O, CO 2 , CH 4 , and N 2 O were included in the calculations. The IR radiative forcing was calculated using a correlated k-distribution radiative transfer model. The tropospheric radiative forcing values are compared to the IPCC formulae for ozone tropospheric forcing as well as other published values to determine the validity of the correlated k-distribution approach to the radiative forcing calculations. The results for the global average atmosphere show agreement with previous results to the order of 10 percent. We conclude that the O 3 forcing is linear in the background abundance and that the radiative forcing for ozone for the globally averaged atmosphere and the latitude averaged radiative forcing in the clear sky approximation are in agreement to within 10 percent. For the case of an atmosphere in which the tropospheric ozone has been depleted by 25 ppbv at all altitudes in the northern hemisphere, the mid latitude zone contributes ∼50 percent of the forcing, tropic zone contributes ∼37 percent of the forcing and the polar zone contributes ∼13 percent of the total forcing

  2. Surface radiative forcing of forest disturbances over northeastern China

    International Nuclear Information System (INIS)

    Zhang, Yuzhen; Liang, Shunlin

    2014-01-01

    Forests provide important climate forcing through biogeochemical and biogeophysical processes. In this study, we investigated the climatic effects of forest disturbances due to changes in forest biomass and surface albedo in terms of radiative forcing over northeastern China. Four types of forest disturbances were considered: fires, insect damage, logging, and afforestation and reforestation. The mechanisms of the influence of forest disturbances on climate were different. ‘Instantaneous’ net radiative forcings caused by fires, insect damage, logging, and afforestation and reforestation were estimated at 0.53 ± 0.08 W m −2 , 1.09 ± 0.14 W m −2 , 2.23 ± 0.27 W m −2 , and 0.14 ± 0.04 W m −2 , respectively. Trajectories of CO 2 -driven radiative forcing, albedo-driven radiative forcing, and net forcing were different with time for each type of disturbance. Over a decade, the estimated net forcings were 2.24 ± 0.11 W m −2 , 0.20 ± 0.31 W m −2 , 1.06 ± 0.41 W m −2 , and −0.47 ± 0.07 W m −2 , respectively. These estimated radiative forcings from satellite observations provided evidence for the mechanisms of the influences of forest disturbances on climate. (paper)

  3. A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility. Part II; Cloud Fraction and Radiative Forcing

    Science.gov (United States)

    Dong, Xiquan; Xi, Baike; Minnis, Patrick

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) central facility are analyzed for determining the variability of cloud fraction and radiative forcing at several temporal scales between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layer low (0-3 km), middle (3-6 km), and high clouds (greater than 6 km) using ARM SGP ground-based paired lidar-radar measurements. Shortwave (SW), longwave (LW), and net cloud radiative forcings (CRF) are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements. The annual averages of total, and single-layer, nonoverlapped low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Total and low cloud amounts were greatest from December through March and least during July and August. The monthly variation of high cloud amount is relatively small with a broad maximum from May to August. During winter, total cloud cover varies diurnally with a small amplitude, mid-morning maximum and early evening minimum, and during summer it changes by more than 0.14 over the daily cycle with a pronounced early evening minimum. The diurnal variations of mean single-layer cloud cover change with season and cloud height. Annual averages of all-sky, total, and single-layer high, middle, and low LW CRFs are 21.4, 40.2, 16.7, 27.2, and 55.0 Wm(sup -2), respectively; and their SW CRFs are -41.5, -77.2, -37.0, -47.0, and -90.5 Wm(sup -2). Their net CRFs range from -20 to -37 Wm(sup -2). For all-sky, total, and low clouds, the maximum negative net CRFs of -40.1, -70, and -69.5 Wm(sup -2), occur during April; while the respective minimum values of -3.9, -5.7, and -4.6 Wm(sup -2), are found during December. July is the month having maximum negative net CRF of -46.2 Wm(sup -2) for middle clouds, and May has the maximum value of -45.9 Wm(sup -2) for high clouds. An

  4. Radiation-Force Assisted Targeting Facilitates Ultrasonic Molecular Imaging

    Directory of Open Access Journals (Sweden)

    Shukui Zhao

    2004-07-01

    Full Text Available Ultrasonic molecular imaging employs contrast agents, such as microbubbles, nanoparticles, or liposomes, coated with ligands specific for receptors expressed on cells at sites of angiogenesis, inflammation, or thrombus. Concentration of these highly echogenic contrast agents at a target site enhances the ultrasound signal received from that site, promoting ultrasonic detection and analysis of disease states. In this article, we show that acoustic radiation force can be used to displace targeted contrast agents to a vessel wall, greatly increasing the number of agents binding to available surface receptors. We provide a theoretical evaluation of the magnitude of acoustic radiation force and show that it is possible to displace micron-sized agents physiologically relevant distances. Following this, we show in a series of experiments that acoustic radiation force can enhance the binding of targeted agents: The number of biotinylated microbubbles adherent to a synthetic vessel coated with avidin increases as much as 20-fold when acoustic radiation force is applied; the adhesion of contrast agents targeted to αvβ3 expressed on human umbilical vein endothelial cells increases 27-fold within a mimetic vessel when radiation force is applied; and finally, the image signal-to-noise ratio in a phantom vessel increases up to 25 dB using a combination of radiation force and a targeted contrast agent, over use of a targeted contrast agent alone.

  5. Black carbon radiative forcing at TOA decreased during aging.

    Science.gov (United States)

    Wu, Yu; Cheng, Tianhai; Zheng, Lijuan; Chen, Hao

    2016-12-05

    During aging processing, black carbon (also called soot) particles may tend to be mixed with other aerosols, and highly influence their radiative forcing. In this study, freshly emitted soot particles were simulated as fractal aggregates composed of small spherical primary monomers. After aging in the atmosphere, soot monomers were coated by a thinly layer of sulfate as thinly coated soot particles. These soot particles were entirely embedded into large sulfate particle by further aging, and becoming heavily coated soot particles. In clear-sky conditions, black carbon radiative forcing with different aging states were investigated for the bottom and top of atmosphere (BOA and TOA). The simulations showed that black carbon radiative forcing increased at BOA and decreased at TOA after their aging processes. Thinly and heavily coated states increased up to ~12% and ~35% black carbon radiative forcing at BOA, and black carbon radiative forcing at TOA can reach to ~20% and ~100% smaller for thinly and heavily coated states than those of freshly emitted states, respectively. The effect of aging states of black carbon radiative forcing was varied with surface albedo, aerosol optical depth and solar zenith angles. These findings would be helpful for the assessments of climate change.

  6. The Effect of Forcing on Vacuum Radiation

    OpenAIRE

    Jones-Smith, Katherine; Mathur, Harsh; Lowenstein, Ashton

    2018-01-01

    Vacuum radiation has been the subject of theoretical study in both cosmology and condensed matter physics for many decades. Recently there has been impressive progress in experimental realizations as well. Here we study vacuum radiation when a field mode is driven both parametrically and by a classical source. We find that in the Heisenberg picture the field operators of the mode undergo a Bogolyubov transformation combined with a displacement, in the Schr\\"odinger picture the oscillator evol...

  7. On the role of coulomb forces in atomic radiative emission

    International Nuclear Information System (INIS)

    Yngstroem, S.

    1988-10-01

    It is shown how the generalized Coulomb interaction (electric and magnetic fields of force) competes with the radiative interaction causing overall inhibition of the radiative capability of atoms and ions in a gaseous sample of matter. Basic quantum mechanical aspects of the electromagnetic interaction are discussed in a heuristic introduction followed by a more precise treatment in the formalism of relativistic quantum electrodynamics. (author)

  8. Observationally constrained estimates of carbonaceous aerosol radiative forcing.

    Science.gov (United States)

    Chung, Chul E; Ramanathan, V; Decremer, Damien

    2012-07-17

    Carbonaceous aerosols (CA) emitted by fossil and biomass fuels consist of black carbon (BC), a strong absorber of solar radiation, and organic matter (OM). OM scatters as well as absorbs solar radiation. The absorbing component of OM, which is ignored in most climate models, is referred to as brown carbon (BrC). Model estimates of the global CA radiative forcing range from 0 to 0.7 Wm(-2), to be compared with the Intergovernmental Panel on Climate Change's estimate for the pre-Industrial to the present net radiative forcing of about 1.6 Wm(-2). This study provides a model-independent, observationally based estimate of the CA direct radiative forcing. Ground-based aerosol network data is integrated with field data and satellite-based aerosol observations to provide a decadal (2001 through 2009) global view of the CA optical properties and direct radiative forcing. The estimated global CA direct radiative effect is about 0.75 Wm(-2) (0.5 to 1.0). This study identifies the global importance of BrC, which is shown to contribute about 20% to 550-nm CA solar absorption globally. Because of the inclusion of BrC, the net effect of OM is close to zero and the CA forcing is nearly equal to that of BC. The CA direct radiative forcing is estimated to be about 0.65 (0.5 to about 0.8) Wm(-2), thus comparable to or exceeding that by methane. Caused in part by BrC absorption, CAs have a net warming effect even over open biomass-burning regions in Africa and the Amazon.

  9. Variability of the contrail radiative forcing due to crystal shape

    Science.gov (United States)

    Markowicz, K. M.; Witek, M. L.

    2011-12-01

    The aim of this study is to examine the influence of particles' shape and particles' optical properties on the contrail radiative forcing. Contrail optical properties in the shortwave and longwave range are derived using a ray-tracing geometric method and the discrete dipole approximation method, respectively. Both methods present good correspondence of the single scattering albedo and the asymmetry parameter in a transition range (3-7μm). We compare optical properties defined following simple 10 crystals habits randomly oriented: hexagonal plates, hexagonal columns with different aspect ratio, and spherical. There are substantial differences in single scattering properties between ten crystal models investigated here (e.g. hexagonal columns and plates with different aspect ratios, spherical particles). The single scattering albedo and the asymmetry parameter both vary up to 0.1 between various crystal shapes. Radiative forcing calculations were performed using a model which includes an interface between the state-of-the-art radiative transfer model Fu-Liou and databases containing optical properties of the atmosphere and surface reflectance and emissivity. This interface allows to determine radiative fluxes in the atmosphere and to estimate the contrail radiative forcing for clear- and all-sky (including natural clouds) conditions for various crystal shapes. The Fu-Liou code is fast and therefore it is suitable for computing radiative forcing on a global scale. At the same time it has sufficiently good accuracy for such global applications. A noticeable weakness of the Fu-Liou code is that it does not take into account the 3D radiative effects, e.g. cloud shading and horizontal. Radiative transfer model calculations were performed at horizontal resolution of 5x5 degree and time resolution of 20 min during day and 3 h during night. In order to calculate a geographic distribution of the global and annual mean contrail radiative forcing, the contrail cover must be

  10. Measuring the greenhouse effect and radiative forcing through the atmosphere

    Science.gov (United States)

    Philipona, Rolf; Kräuchi, Andreas; Brocard, Emmanuel

    2013-04-01

    In spite of a large body of existing measurements of incoming shortwave solar radiation and outgoing longwave terrestrial radiation at the Earth's surface and at the top of the atmosphere, there are few observations documenting how radiation profiles change through the atmosphere - information that is necessary to fully quantify the greenhouse effect of the Earth's atmosphere. Using weather balloons and specific radiometer equipped radiosondes, we continuously measured shortwave and longwave radiation fluxes from the surface of the Earth up to altitudes of 35 kilometers in the upper stratosphere. Comparing radiation profiles from night measurements with different amounts of water vapor, we show evidence of large greenhouse forcing. We show, that under cloud free conditions, water vapor increases with Clausius-Clapeyron ( 7% / K), and longwave downward radiation at the surface increases by 8 Watts per square meter per Kelvin. The longwave net radiation however, shows a positive increase (downward) of 2.4 Watts per square meter and Kelvin at the surface, which decreases with height and shows a similar but negative increase (upward) at the tropopause. Hence, increased tropospheric water vapor increases longwave net radiation towards the ground and towards space, and produces a heating of 0.42 Kelvin per Watt per square meter at the surface. References: Philipona et al., 2012: Solar and thermal radiation profiles and radiative forcing measured through the atmosphere. Geophys. Res. Lett., 39, L13806, doi: 10.1029/2012GL052087.

  11. Forcing the issue on radiation policy

    International Nuclear Information System (INIS)

    Rockwell, T.

    1999-01-01

    For those frustrated by an inability to get a fair hearing on evidence that challenges current radiation policy, the recent case of a group of tobacco interests suing the US Environmental Protection Agency (EPA) in Federal court on its policy on second-hand smoke has important implications for radiation policy. The issue was only tangentially about tobacco; its main thrust was at EPA's arbitrary and capricious rule-making process. The EPA is at least as vulnerable to the same charges in the radiation area, particularly with respect to radon. Radiation protection is associated in many people's minds with the US Nuclear Regulatory Commission (NRC), but other agencies have also been involved. Radon, like second-hand smoke, has been tolerated for generations, and EPA has the burden of proving that it is a public hazard. The law and the unwritten rules of science are quite explicit in defining what must be done to make such a finding. In the case of radon, there is no prior basis for public concern. In fact, the public uses radium spas with radon concentrations up to one million times as high as the EPA permissible limit. In many countries, such spa usage is formally prescribed by physicians and paid for by national health insurance. The health effects, if any, from radon, as from second-hand smoke, are hard to quantify. But, this does not justify--in either case--the EPA's straying from its published criteria and procedures for testing whether such health effects occur. A Federal court has now demonstrated its willingness to judge and strike down the EPA's actions regarding second-hand smoke on their own merits, without attempting to be an arbiter of science. The result is a welcome breath of fresh air and an object lesson for those concerned about the mounting costs of treating radon as a major public health hazard

  12. Radiation reaction force and unification of electromagnetic and gravitational fields

    International Nuclear Information System (INIS)

    Lo, C.Y.; Goldstein, G.R.; Napier, A.

    1981-04-01

    A unified theory of electromagnetic and gravitational fields should modify classical electrodynamics such that the radiation reaction force is accounted for. The analysis leads to a five-dimensional unified theory of five variables. The theory is supported by showing that, for the case of a charged particle moving in a constant magnetic field, the radiation reaction force is indeed included. Moreover, this example shows explicitly that physical changes are associated with the fifth variable. Thus, the notion of a physical five-dimensional space should be seriously taken into consideration

  13. Impact of Dust Radiative Forcing upon Climate. Chapter 13

    Science.gov (United States)

    Miller, Ronald L.; Knippertz, Peter; Perez Garcia-Pando, Carlos; Perlwitz, Jan P.; Tegan, Ina

    2014-01-01

    Dust aerosols perturb the atmospheric radiative flux at both solar and thermal wavelengths, altering the energy and water cycles. The climate adjusts by redistributing energy and moisture, so that local temperature perturbations, for example, depend upon the forcing over the entire extent of the perturbed circulation. Within regions frequently mixed by deep convection, including the deep tropics, dust particles perturb the surface air temperature primarily through radiative forcing at the top of the atmosphere (TOA). Many models predict that dust reduces global precipitation. This reduction is typically attributed to the decrease of surface evaporation in response to dimming of the surface. A counterexample is presented, where greater shortwave absorption by dust increases evaporation and precipitation despite greater dimming of the surface. This is attributed to the dependence of surface evaporation upon TOA forcing through its influence upon surface temperature and humidity. Perturbations by dust to the surface wind speed and vegetation (through precipitation anomalies) feed back upon the dust aerosol concentration. The current uncertainty of radiative forcing attributed to dust and the resulting range of climate perturbations calculated by models remain a useful test of our understanding of the mechanisms relating dust radiative forcing to the climate response.

  14. Black Carbon Radiative Forcing over the Tibetan Plateau

    Energy Technology Data Exchange (ETDEWEB)

    He, Cenlin; Li, Qinbin; Liou, K. N.; Takano, Y.; Gu, Yu; Qi, L.; Mao, Yuhao; Leung, Lai-Yung R.

    2014-11-28

    We estimate the snow albedo forcing and direct radiative forcing (DRF) of black carbon (BC) in the Tibetan Plateau using a global chemical transport model in conjunction with a stochastic snow model and a radiative transfer model. Our best estimate of the annual BC snow albedo forcing in the Plateau is 2.9 W m-2 (uncertainty: 1.5–5.0 W m-226 ). We find that BC-snow internal mixing increases the albedo forcing by 40-60% compared with external mixing and coated BC increases the forcing by 30-50% compared with uncoated BC, whereas Koch snowflakes reduce the forcing by 20-40% relative to spherical snow grains. Our best estimate of the annual BC DRF at the top of the atmosphere is 2.3 W m-2 (uncertainty: 0.7–4.3 W m-230 ) in the Plateau after scaling the modeled BC absorption optical depth to Aerosol Robotic Network (AERONET) observations. The BC forcings are attributed to emissions from different regions.

  15. Active electromagnetic invisibility cloaking and radiation force cancellation

    Science.gov (United States)

    Mitri, F. G.

    2018-03-01

    This investigation shows that an active emitting electromagnetic (EM) Dirichlet source (i.e., with axial polarization of the electric field) in a homogeneous non-dissipative/non-absorptive medium placed near a perfectly conducting boundary can render total invisibility (i.e. zero extinction cross-section or efficiency) in addition to a radiation force cancellation on its surface. Based upon the Poynting theorem, the mathematical expression for the extinction, radiation and amplification cross-sections (or efficiencies) are derived using the partial-wave series expansion method in cylindrical coordinates. Moreover, the analysis is extended to compute the self-induced EM radiation force on the active source, resulting from the waves reflected by the boundary. The numerical results predict the generation of a zero extinction efficiency, achieving total invisibility, in addition to a radiation force cancellation which depend on the source size, the distance from the boundary and the associated EM mode order of the active source. Furthermore, an attractive EM pushing force on the active source directed toward the boundary or a repulsive pulling one pointing away from it can arise accordingly. The numerical predictions and computational results find potential applications in the design and development of EM cloaking devices, invisibility and stealth technologies.

  16. Experimental Characterization of Radiation Forcing due to Atmospheric Aerosols

    Science.gov (United States)

    Sreenivas, K. R.; Singh, D. K.; Ponnulakshmi, V. K.; Subramanian, G.

    2011-11-01

    Micro-meteorological processes in the nocturnal atmospheric boundary layer (NBL) including the formation of radiation-fog and the development of inversion layers are controlled by heat transfer and the vertical temperature distribution close to the ground. In a recent study, it has been shown that the temperature profile close to the ground in stably-stratified, NBL is controlled by the radiative forcing due to suspended aerosols. Estimating aerosol forcing is also important in geo-engineering applications to evaluate the use of aerosols to mitigate greenhouse effects. Modeling capability in the above scenarios is limited by our knowledge of this forcing. Here, the design of an experimental setup is presented which can be used for evaluating the IR-radiation forcing on aerosols under either Rayleigh-Benard condition or under conditions corresponding to the NBL. We present results indicating the effect of surface emissivities of the top and bottom boundaries and the aerosol concentration on the temperature profiles. In order to understand the observed enhancement of the convection-threshold, we have determined the conduction-radiation time constant of an aerosol laden air layer. Our results help to explain observed temperature profiles in the NBL, the apparent stability of such profiles and indicate the need to account for the effect of aerosols in climatic/weather models.

  17. Laser radiation forces in laser-produced plasmas

    International Nuclear Information System (INIS)

    Stamper, J.A.

    1975-01-01

    There are two contributions to laser radiation forces acting on the electrons. Transfer of momentum from the fields to the electrons results in a field pressure contribution and occurs whenever there is absorption or reflection. The quiver pressure contribution, associated with electron quiver motion, is due to inhomogeneous fields inducing momentum transfer within the electron system. It is shown that the ponderomotive force with force density, (epsilon-1)/8πdel 2 >, does not include the field contribution and does not lead to a general description of macroscopic processes. A theory is discussed which does give a general macroscopic description (absorption, reflection, refraction, and magnetic field generation) and which reduces to the ponderomotive force for purely sinusoidal fields in a neutral, homogeneous, nonabsorbing plasma

  18. Cooling and trapping neutral atoms with radiative forces

    International Nuclear Information System (INIS)

    Bagnato, V.S.; Castro, J.C.; Li, M.S.; Zilio, S.C.

    1988-01-01

    Techniques to slow and trap neutral atoms at high densities with radiative forces are discussed in this review articles. Among several methods of laser cooling, it is emphasized Zeeman Tuning of the electronic levels and frequency-sweeping techniques. Trapping of neutral atoms and recent results obtained in light and magnetic traps are discussed. Techniques to further cool atoms inside traps are presented and the future of laser cooling of neutral atoms by means of radiation pressure is discussed. (A.C.A.S.) [pt

  19. Air pollution radiative forcing from specific emissions sectors at 2030

    Science.gov (United States)

    Unger, Nadine; Shindell, Drew T.; Koch, Dorothy M.; Streets, David G.

    2008-01-01

    Reduction of short-lived air pollutants can contribute to mitigate global warming in the near-term with ancillary benefits to human health. However, the radiative forcings of short-lived air pollutants depend on the location and source type of the precursor emissions. We apply the Goddard Institute for Space Studies atmospheric composition-climate model to quantify near-future (2030 A1B) global annual mean radiative forcing by ozone (O3) and sulfate from six emissions sectors in seven geographic regions. At 2030 the net forcings from O3, sulfate, black and organic carbon, and indirect CH4 effects for each emission sector are (in mWm-2) biomass burning, +95; domestic, +68; transportation, +67; industry, -131; and power, -224. Biomass burning emissions in East Asia and central and southern Africa, domestic biofuel emissions in East Asia, south Asia, and central and southern Africa, and transportation emissions in Europe and North America have large net positive forcings and are therefore attractive targets to counter global warming. Power and industry emissions from East Asia, south Asia, and north Africa and the Middle East have large net negative forcings. Therefore air quality control measures that affect these regional sectors require offsetting climate measures to avoid a warming impact. Linear relationships exist between O3 forcing and biomass burning and domestic biofuel CO precursor emissions independent of region with sensitivity of +0.2 mWm-2/TgCO. Similarly, linear relationships exist between sulfate forcing and SO2 precursor emissions that depend upon region but are independent of sector with sensitivities ranging from -3 to -12 mWm-2/TgS.

  20. One-dimensional central-force problem, including radiation reaction

    International Nuclear Information System (INIS)

    Kasher, J.C.

    1976-01-01

    Two equal masses of equal charge magnitude (either attractive or repulsive) are held a certain distance apart for their entire past history. AT t = 0 one of them is either started from rest or given an initial velocity toward or away from the other charge. When the Dirac radiation-reaction force is included in the force equation, our Taylor-series numerical calculations lead to two types of nonphysical results for both the attractive and repulsive cases. In the attractive case, the moving charge either stops and moves back out to infinity, or violates energy conservation as it nears collision with the fixed charge. For the repulsive charges, the moving particle either eventually approaches and collides with the fixed one, or violates energy conservation as it goes out to infinity. These results lead us to conclude that the Lorentz-Dirac equation is not valid for the one-dimensional central-force problem

  1. Electromagnetic radiation reaction force and radiation potential in general five-dimensional relativity

    International Nuclear Information System (INIS)

    Lo, C.Y.; Goldstein, G.R.; Napier, A.

    1989-01-01

    A unified theory of electromagnetic and gravitational fields should modify classical electrodynamics to account for the radiation reaction force. A conjecture that the radiation reaction force and the Lorentz force should be distinct, but in unified forms, results in a five-dimensional unified theory of five variables. It is found that a semicylindrical condition can reconcile the apparent differences between a five-dimensional physical space and our four-dimensional perceptions. Analysis of the geodesic equations results in the notion of gauge dynamics which manifests the influence of the unrestricted fifth variable. The element g 55 of the five-dimensional metric is identified as the radiation potential, which can directly determine the radiation reaction force. This gives a distinct physical origin for the radiation process in classical theory. The potential suggests that the electron can have excited states in quantum electrodynamics. This theory is supported with calculations which demonstrate that the motion of the fifth variable directly causes physical changes in the four-dimensional subspace

  2. Nonlinear aspects of acoustic radiation force in biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Ostrovsky, Lev, E-mail: Lev.A.Ostrovsky@noaa.gov [NOAA Earth System Research Laboratory, 325 Broadway, Boulder, Colorado 80305 (United States); Tsyuryupa, Sergey; Sarvazyan, Armen, E-mail: armen@artannlabs.com [Artann Laboratories, Inc., 1459 Lower Ferry Rd., West Trenton, New Jersey,08618 (United States)

    2015-10-28

    In the past decade acoustic radiation force (ARF) became a powerful tool in numerous biomedical applications. ARF from a focused ultrasound beam acts as a virtual “finger” for remote probing of internal anatomical structures and obtaining diagnostic information. This presentation deals with generation of shear waves by nonlinear focused beams. Albeit the ARF has intrinsically nonlinear origin, in most cases the primary ultrasonic wave was considered in the linear approximation. In this presentation, we consider the effects of nonlinearly distorted beams on generation of shear waves by such beams.

  3. Nonlinear aspects of acoustic radiation force in biomedical applications

    International Nuclear Information System (INIS)

    Ostrovsky, Lev; Tsyuryupa, Sergey; Sarvazyan, Armen

    2015-01-01

    In the past decade acoustic radiation force (ARF) became a powerful tool in numerous biomedical applications. ARF from a focused ultrasound beam acts as a virtual “finger” for remote probing of internal anatomical structures and obtaining diagnostic information. This presentation deals with generation of shear waves by nonlinear focused beams. Albeit the ARF has intrinsically nonlinear origin, in most cases the primary ultrasonic wave was considered in the linear approximation. In this presentation, we consider the effects of nonlinearly distorted beams on generation of shear waves by such beams

  4. Nonlinear aspects of acoustic radiation force in biomedical applications

    Science.gov (United States)

    Ostrovsky, Lev; Tsyuryupa, Sergey; Sarvazyan, Armen

    2015-10-01

    In the past decade acoustic radiation force (ARF) became a powerful tool in numerous biomedical applications. ARF from a focused ultrasound beam acts as a virtual "finger" for remote probing of internal anatomical structures and obtaining diagnostic information. This presentation deals with generation of shear waves by nonlinear focused beams. Albeit the ARF has intrinsically nonlinear origin, in most cases the primary ultrasonic wave was considered in the linear approximation. In this presentation, we consider the effects of nonlinearly distorted beams on generation of shear waves by such beams.

  5. Time evolution of tropospheric ozone and its radiative forcing

    International Nuclear Information System (INIS)

    Berntsen, Terje K.; Isaksen, Ivar S.A.; Myhre, Gunnar; Stordal, Frode

    1999-01-01

    The overview presents results from studies of ozone concentrations from pre industrial time and up to the end of the 20th century. Different models and also a global 3-D chemistry transport model have been used. Experiments have been performed for 1850, 1900, 1950, 1960, 1970, 1980 and 1990. The radiative forcing increases with increasing ozone levels and has been steadily increasing. It has escalated towards the end of the century. Comparative evaluations with project results and external results are presented. Connections to other greenhouse gases are mentioned

  6. Spectral Longwave Cloud Radiative Forcing as Observed by AIRS

    Science.gov (United States)

    Blaisdell, John M.; Susskind, Joel; Lee, Jae N.; Iredell, Lena

    2016-01-01

    AIRS V6 products contain the spectral contributions to Outgoing Longwave Radiation (OLR), clear-sky OLR (OLR(sub CLR)), and Longwave Cloud Radiative Forcing (LWCRF) in 16 bands from 100 cm(exp -1) to 3260 cm(exp -1). We show climatologies of selected spectrally resolved AIRS V6 products over the period of September 2002 through August 2016. Spectrally resolved LWCRF can better describe the response of the Earth system to cloud and cloud feedback processes. The spectral LWCRF enables us to estimate the fraction of each contributing factor to cloud forcing, i.e.: surface temperature, mid to upper tropospheric water vapor, and tropospheric temperature. This presentation also compares the spatial characteristics of LWCRF from AIRS, CERES_EBAF Edition-2.8, and MERRA-2. AIRS and CERES LWCRF products show good agreement. The OLR bias between AIRS and CERES is very close to that of OLR(sub CLR). This implies that both AIRS and CERES OLR products accurately account for the effect of clouds on OLR.

  7. Impact of nonlinear distortion on acoustic radiation force elastography.

    Science.gov (United States)

    Draudt, Andrew B; Cleveland, Robin O

    2011-11-01

    High-intensity focused ultrasound (HIFU) produces an acoustic radiation force that induces tissue displacement, which can be measured by monitoring time shifts in the backscattered signals from interrogation pulses. If the pulse occurs simultaneously with the HIFU, the arrival time of the backscatter will be biased because nonlinearity associated with the HIFU changes the local sound speed. Measurements of the pressure field using 1.1 MHz HIFU and a 7.5 MHz pulse in water exhibited a nonlinearly induced apparent displacement (NIAD) that varied with the HIFU pressure, propagation distance and the timing of the pulse relative to the HIFU. Nonlinear simulations employing the KZK equation predicted NIADs that agreed with measurements. Experiments with chicken breast demonstrated a NIAD with magnitude similar to that expected from the radiation force. Finally it was shown that if two pulses were fired with different phases relative to the HIFU, then upon averaging, the NIAD could be mitigated. Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  8. Contrasting regional versus global radiative forcing by megacity pollution emissions

    Science.gov (United States)

    Dang, H.; Unger, N.

    2015-10-01

    We assess the regional and global integrated radiative forcing on 20- and 100-year time horizons caused by a one-year pulse of present day pollution emissions from 10 megacity areas: Los Angeles, Mexico City, New York City, Sao Paulo, Lagos, Cairo, New Delhi, Beijing, Shanghai and Manila. The assessment includes well-mixed greenhouse gases: carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4); and short-lived climate forcers: tropospheric ozone (O3) and fine mode aerosol particles (sulfate, nitrate, black carbon, primary and secondary organic aerosol). All megacities contribute net global warming on both time horizons. Most of the 10 megacity areas exert a net negative effect on their own regional radiation budget that is 10-100 times larger in magnitude than their global radiative effects. Of the cities examined, Beijing, New Delhi, Shanghai and New York contribute most to global warming with values ranging from +0.03 to 0.05 Wm-2yr on short timescales and +0.07-0.10 Wm-2yr on long timescales. Regional net 20-year radiative effects are largest for Mexico City (-0.84 Wm-2yr) and Beijing (-0.78 Wm-2yr). Megacity reduction of non-CH4 O3 precursors to improve air quality offers zero co-benefits to global climate. Megacity reduction of aerosols to improve air quality offers co-benefits to the regional radiative budget but minimal or no co-benefits to global climate with the exception of black carbon reductions in a few cities, especially Beijing and New Delhi. Results suggest that air pollution and global climate change mitigation can be treated as separate environmental issues in policy at the megacity level with the exception of CH4 action. Individual megacity reduction of CO2 and CH4 emissions can mitigate global warming and therefore offers climate safety improvements to the entire planet.

  9. Radiative forcing in the ACCMIP historical and future climate simulations

    Directory of Open Access Journals (Sweden)

    D. T. Shindell

    2013-03-01

    Full Text Available The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5. The models reproduce present-day total aerosol optical depth (AOD relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980–2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. We examine both the direct radiative forcing (RF and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects. The models' all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range −0.26 W m−2; −0.06 to −0.49 W m−2. Screening based on model skill in capturing observed AOD yields a best estimate of −0.42 W m−2; −0.33 to −0.50 W m−2, including adjustment for missing aerosol components in some models. Many ACCMIP and CMIP5 models appear to produce substantially smaller aerosol RF than this best estimate. Climate feedbacks contribute substantially (35 to −58% to modeled historical aerosol RF. The 1850 to 2000 aerosol ERF is −1.17 W m−2; −0.71 to −1.44 W m−2. Thus adjustments, including clouds, typically cause greater forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic. Global aerosol RF

  10. Radiative forcing in the ACCMIP historical and future climate simulations

    Energy Technology Data Exchange (ETDEWEB)

    Shindell, D. T.; Lamarque, J. -F.; Schulz, M.; Flanner, M.; Jiao, C.; Chin, M.; Young, P. J.; Lee, Y. H.; Rotstayn, L.; Mahowald, N.; Milly, G.; Faluvegi, G.; Balkanski, Y.; Collins, W. J.; Conley, A. J.; Dalsoren, S.; Easter, R.; Ghan, S.; Horowitz, L.; Liu, X.; Myhre, G.; Nagashima, T.; Naik, V.; Rumbold, S. T.; Skeie, R.; Sudo, K.; Szopa, S.; Takemura, T.; Voulgarakis, A.; Yoon, J. -H.; Lo, F.

    2013-01-01

    The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5). The models reproduce present-day total aerosol optical depth (AOD) relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980-2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. We examine both the direct radiative forcing (RF) and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects). The models’ all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range) -0.26Wm-2-2. Screening based on model skill in capturing observed AOD yields a best estimate of -0.42Wm-2-2-2-2forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic. Global

  11. Radiative Forcing from Emissivity Response in Polar Regions

    Science.gov (United States)

    Kuo, C.; Feldman, D.; Huang, X.; Flanner, M.; Chen, X.; Yang, P.; Kuo, C.

    2016-12-01

    A detailed assessment of the radiative balance and its controlling factors in polar regions is a critical prerequisite for understanding and predicting the polar amplification of climate change. Accordingly, we investigate the role of infrared surface emissivity in polar regions as a potential feedback mechanism following Feldman et al, 2014. In this work, we investigate the climatic response of the Community Earth System Model (CESM) with spectral emissivity values that are implemented in a physically consistent manner for non-vegetated surfaces. In a control model run where 1850 CO2 volume mixing ratio (vmr) is fixed, the updated spectral emissivity values are imposed for modified surface boundary conditions in the atmospheric model component. Climatic stability in the emergent globally averaged surface temperature is observed on decadal scales for an unforced (control) run. Analytic kernels representing the change in top of the atmosphere OLR given changes in emissivity are calculated on-line during the model runs, incorporating spatially and temporally varied humidity profiles impactful to transmission. Globally averaged kernels of the sensitivity of OLR to surface emissivity calculated for control and ramped CO2 runs exhibit temporal evolution with statistically significant differences in shape. Additionally, kernel and spectrally-averaged emissivity differences between monthly-averaged maps of control and ramped runs demonstrate a seasonal cycle. Similar to the treatment of cryosphere radiative forcing in Flanner et al, 2011, we define emissivity response as the product of the emissivity kernel and the change in month-to-month emissivity. At the end of 20th century, the 10-year emissivity forcing averaged at latitudes > 60°, is found to be negative (positive) in January (July), due to increasing (decreasing) sea-ice. These findings indicate that differences in surface emissivity between frozen and unfrozen surfaces decrease wintertime and increase summertime

  12. Radiative Forcing in the ACCMIP Historical and Future Climate Simulations

    Science.gov (United States)

    Shindell, Drew Todd; Lamarque, J.-F.; Schulz, M.; Flanner, M.; Jiao, C.; Chin, M.; Young, P. J.; Lee, Y. H.; Rotstayn, L.; Mahowald, N.; hide

    2013-01-01

    A primary goal of the Atmospheric Chemistry and Climate Model IntercomparisonProject (ACCMIP) was to characterize the short-lived drivers of preindustrial to 2100climate change in the current generation of climate models. Here we evaluate historicaland 5 future radiative forcing in the 10 ACCMIP models that included aerosols, 8 of whichalso participated in the Coupled Model Intercomparison Project phase 5 (CMIP5).The models generally reproduce present-day climatological total aerosol opticaldepth (AOD) relatively well. components to this total, however, and most appear to underestimate AOD over East10 Asia. The models generally capture 1980-2000 AOD trends fairly well, though theyunderpredict AOD increases over the YellowEastern Sea. They appear to strongly underestimate absorbing AOD, especially in East Asia, South and Southeast Asia, SouthAmerica and Southern Hemisphere Africa.We examined both the conventional direct radiative forcing at the tropopause (RF) and the forcing including rapid adjustments (adjusted forcing AF, including direct andindirect effects). The models calculated all aerosol all-sky 1850 to 2000 global meanannual average RF ranges from 0.06 to 0.49 W m(sup -2), with a mean of 0.26 W m(sup -2) and a median of 0.27 W m(sup -2. Adjusting for missing aerosol components in some modelsbrings the range to 0.12 to 0.62W m(sup -2), with a mean of 0.39W m(sup -2). Screen20ing the models based on their ability to capture spatial patterns and magnitudes ofAOD and AOD trends yields a quality-controlled mean of 0.42W m(sup -2) and range of0.33 to 0.50 W m(sup -2) (accounting for missing components). The CMIP5 subset of ACCMIPmodels spans 0.06 to 0.49W m(sup -2), suggesting some CMIP5 simulations likelyhave too little aerosol RF. A substantial, but not well quantified, contribution to histori25cal aerosol RF may come from climate feedbacks (35 to 58). The mean aerosol AF during this period is 1.12W m(sup -2) (median value 1.16W m(sup -2), range 0.72 to1.44W m

  13. The radiative forcing potential of different climate geoengineering options

    Directory of Open Access Journals (Sweden)

    T. M. Lenton

    2009-08-01

    Full Text Available Climate geoengineering proposals seek to rectify the Earth's current and potential future radiative imbalance, either by reducing the absorption of incoming solar (shortwave radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in terms of radiative forcing potential. We use a simple analytical approach, based on energy balance considerations and pulse response functions for the decay of CO2 perturbations. This aids transparency compared to calculations with complex numerical models, but is not intended to be definitive. It allows us to compare the relative effectiveness of a range of proposals. We consider geoengineering options as additional to large reductions in CO2 emissions. By 2050, some land carbon cycle geoengineering options could be of comparable magnitude to mitigation "wedges", but only stratospheric aerosol injections, albedo enhancement of marine stratocumulus clouds, or sunshades in space have the potential to cool the climate back toward its pre-industrial state. Strong mitigation, combined with global-scale air capture and storage, afforestation, and bio-char production, i.e. enhanced CO2 sinks, might be able to bring CO2 back to its pre-industrial level by 2100, thus removing the need for other geoengineering. Alternatively, strong mitigation stabilising CO2 at 500 ppm, combined with geoengineered increases in the albedo of marine stratiform clouds, grasslands, croplands and human settlements might achieve a patchy cancellation of radiative forcing. Ocean fertilisation options are only worthwhile if sustained on a millennial timescale and phosphorus addition may have greater long-term potential than iron or nitrogen fertilisation. Enhancing ocean

  14. Radiation forces and the Abraham-Minkowski problem

    Science.gov (United States)

    Brevik, Iver

    2018-04-01

    Recent years have witnessed a number of beautiful experiments in radiation optics. Our purpose with this paper is to highlight some developments of radiation pressure physics in general, and thereafter to focus on the importance of the mentioned experiments in regard to the classic Abraham-Minkowski problem. That means, what is the “correct” expression for electromagnetic momentum density in continuous matter. In our opinion, one often sees that authors over-interpret the importance of their experimental findings with respect to the momentum problem. Most of these experiments are actually unable to discriminate between these energy-momentum tensors at all, since they can be easily described in terms of force expressions that are common for Abraham and Minkowski. Moreover, we emphasize the inherent ambiguity in applying the formal conservation principles to the radiation field in a dielectric, the reason being that the electromagnetic field in matter is only a subsystem which has to be supplemented by the mechanical subsystem to be closed. Finally, we make some suggestions regarding the connection between macroscopic electrodynamics and the Casimir effect, suggesting that there is a limit for the magnitudes of the cutoff parameters in QFT related to surface tension in ordinary hydromechanics.

  15. Novel applications of the temporal kernel method: Historical and future radiative forcing

    Science.gov (United States)

    Portmann, R. W.; Larson, E.; Solomon, S.; Murphy, D. M.

    2017-12-01

    We present a new estimate of the historical radiative forcing derived from the observed global mean surface temperature and a model derived kernel function. Current estimates of historical radiative forcing are usually derived from climate models. Despite large variability in these models, the multi-model mean tends to do a reasonable job of representing the Earth system and climate. One method of diagnosing the transient radiative forcing in these models requires model output of top of the atmosphere radiative imbalance and global mean temperature anomaly. It is difficult to apply this method to historical observations due to the lack of TOA radiative measurements before CERES. We apply the temporal kernel method (TKM) of calculating radiative forcing to the historical global mean temperature anomaly. This novel approach is compared against the current regression based methods using model outputs and shown to produce consistent forcing estimates giving confidence in the forcing derived from the historical temperature record. The derived TKM radiative forcing provides an estimate of the forcing time series that the average climate model needs to produce the observed temperature record. This forcing time series is found to be in good overall agreement with previous estimates but includes significant differences that will be discussed. The historical anthropogenic aerosol forcing is estimated as a residual from the TKM and found to be consistent with earlier moderate forcing estimates. In addition, this method is applied to future temperature projections to estimate the radiative forcing required to achieve those temperature goals, such as those set in the Paris agreement.

  16. Identifying Vulnerable Plaques with Acoustic Radiation Force Impulse Imaging

    Science.gov (United States)

    Doherty, Joshua Ryan

    The rupture of arterial plaques is the most common cause of ischemic complications including stroke, the fourth leading cause of death and number one cause of long term disability in the United States. Unfortunately, because conventional diagnostic tools fail to identify plaques that confer the highest risk, often a disabling stroke and/or sudden death is the first sign of disease. A diagnostic method capable of characterizing plaque vulnerability would likely enhance the predictive ability and ultimately the treatment of stroke before the onset of clinical events. This dissertation evaluates the hypothesis that Acoustic Radiation Force Impulse (ARFI) imaging can noninvasively identify lipid regions, that have been shown to increase a plaque's propensity to rupture, within carotid artery plaques in vivo. The work detailed herein describes development efforts and results from simulations and experiments that were performed to evaluate this hypothesis. To first demonstrate feasibility and evaluate potential safety concerns, finite- element method simulations are used to model the response of carotid artery plaques to an acoustic radiation force excitation. Lipid pool visualization is shown to vary as a function of lipid pool geometry and stiffness. A comparison of the resulting Von Mises stresses indicates that stresses induced by an ARFI excitation are three orders of magnitude lower than those induced by blood pressure. This thesis also presents the development of a novel pulse inversion harmonic tracking method to reduce clutter-imposed errors in ultrasound-based tissue displacement estimates. This method is validated in phantoms and was found to reduce bias and jitter displacement errors for a marked improvement in image quality in vivo. Lastly, this dissertation presents results from a preliminary in vivo study that compares ARFI imaging derived plaque stiffness with spatially registered composition determined by a Magnetic Resonance Imaging (MRI) gold standard

  17. Indirect radiative forcing by ion-mediated nucleation of aerosol

    Directory of Open Access Journals (Sweden)

    F. Yu

    2012-12-01

    Full Text Available A clear understanding of particle formation mechanisms is critical for assessing aerosol indirect radiative forcing and associated climate feedback processes. Recent studies reveal the importance of ion-mediated nucleation (IMN in generating new particles and cloud condensation nuclei (CCN in the atmosphere. Here we implement the IMN scheme into the Community Atmosphere Model version 5 (CAM5. Our simulations show that, compared to globally averaged results based on H2SO4-H2O binary homogeneous nucleation (BHN, the presence of ionization (i.e., IMN halves H2SO4 column burden, but increases the column integrated nucleation rate by around one order of magnitude, total particle number burden by a factor of ~3, CCN burden by ~10% (at 0.2% supersaturation to 65% (at 1.0% supersaturation, and cloud droplet number burden by ~18%. Compared to BHN, IMN increases cloud liquid water path by 7.5%, decreases precipitation by 1.1%, and increases total cloud cover by 1.9%. This leads to an increase of total shortwave cloud radiative forcing (SWCF by 3.67 W m−2 (more negative and longwave cloud forcing by 1.78 W m−2 (more positive, with large spatial variations. The effect of ionization on SWCF derived from this study (3.67 W m−2 is a factor of ~3 higher that of a previous study (1.15 W m−2 based on a different ion nucleation scheme and climate model. Based on the present CAM5 simulation, the 5-yr mean impacts of solar cycle induced changes in ionization rates on CCN and cloud forcing are small (~−0.02 W m−2 but have larger inter-annual (from −0.18 to 0.17 W m−2 and spatial variations.

  18. Solar Radiation as Driving Force In Early Evolution

    Science.gov (United States)

    Rothschild, Lynn J.; Peterson, David L. (Technical Monitor)

    2002-01-01

    Ultraviolet radiation (UVR) has provided an evolutionary challenge to life on Earth in that it is both an agent of mutation and as well as a selective force. Today surface fluxes of UVR vary diurnally, seasonally, etc. Still, the UVR flux was probably substantially higher during the early phases of evolution, suggesting that its role in evolution was even more prominent during this time. In this presentation, the creative role of UVR in evolution is discussed, specifically in connection with the role that UVR may have played in the evolution of early microbial ecosystems. The presentation will include discussions of the direct influence of UVR on such processes as photosynthesis and genetic damage, as well as the indirect influence of UVR as mediated through the production of reactive oxygen species. These biological effects of UVR will be viewed against the backdrop of the physical nature of the early Earth, surely a very different place then than now.

  19. AIRFORCE. Aircraft emissions and radiative forcing from emissions

    Energy Technology Data Exchange (ETDEWEB)

    Meijer, E W; Kelder, H; Velthoven, P F.J. van; Wauben, W M.F. [Royal Netherlands Meteorological Inst., De Bilt (Netherlands); Beck, J P; Velders, G J.M. [National Inst. of Public Health and the Environment, Bilthoven (Netherlands); Lelieveld, J; Scheeren, B A [Institute of Marine and Atmospheric Research Utrecht (Netherlands)

    1998-12-31

    The Dutch AIRFORCE project focuses on the effects of subsonic aircraft emissions on the chemical composition of the atmosphere and subsequent radiative forcing. It includes measurements in the tropopause region and the modelling of exhaust plumes and large-scale effects. An aircraft exhaust plume model has been developed to study plume processes. The results of the plume model are used in the global transport chemistry model CTMK to determine large-scale effects of plume processes. Due to the efficient conversion of NO{sub x} into HNO{sub 3} inside aircraft exhaust plumes, a decrease of about 25% of the O{sub 3} perturbation was found in the NAFC at 200 hPa in July. Measurements of hydrocarbons revealed a dominant role of the anthropogenic continental emissions of light hydrocarbons in the tropopause region. (author) 20 refs.

  20. AIRFORCE. Aircraft emissions and radiative forcing from emissions

    Energy Technology Data Exchange (ETDEWEB)

    Meijer, E.W.; Kelder, H.; Velthoven, P.F.J. van; Wauben, W.M.F. [Royal Netherlands Meteorological Inst., De Bilt (Netherlands); Beck, J.P.; Velders, G.J.M. [National Inst. of Public Health and the Environment, Bilthoven (Netherlands); Lelieveld, J.; Scheeren, B.A. [Institute of Marine and Atmospheric Research Utrecht (Netherlands)

    1997-12-31

    The Dutch AIRFORCE project focuses on the effects of subsonic aircraft emissions on the chemical composition of the atmosphere and subsequent radiative forcing. It includes measurements in the tropopause region and the modelling of exhaust plumes and large-scale effects. An aircraft exhaust plume model has been developed to study plume processes. The results of the plume model are used in the global transport chemistry model CTMK to determine large-scale effects of plume processes. Due to the efficient conversion of NO{sub x} into HNO{sub 3} inside aircraft exhaust plumes, a decrease of about 25% of the O{sub 3} perturbation was found in the NAFC at 200 hPa in July. Measurements of hydrocarbons revealed a dominant role of the anthropogenic continental emissions of light hydrocarbons in the tropopause region. (author) 20 refs.

  1. Placement and efficiency effects on radiative forcing of solar installations

    International Nuclear Information System (INIS)

    Burg, Brian R.; Ruch, Patrick; Paredes, Stephan; Michel, Bruno

    2015-01-01

    The promise for harnessing solar energy being hampered by cost, triggered efforts to reduce them. As a consequence low-efficiency, low-cost photovoltaics (PV) panels prevail. Conversely, in the traditional energy sector efficiency is extremely important due to the direct costs associated to fuels. This also affects solar energy due to the radiative forcing caused by the dark solar panels. In this paper we extend the concept of energy payback time by including the effect of albedo change, which gives a better assessment of the system sustainability. We present an analysis on the short and medium term climate forcing effects of different solar collectors in Riyadh, Saudi Arabia and demonstrate that efficiency is important to reduce the collector area and cost. This also influences the embodied energy and the global warming potential. We show that a placement of a high concentration photovoltaic thermal solar power station outside of the city using a district cooling system has a double beneficial effect since it improves the solar conversion efficiency and reduces the energy demand for cooling in the city. We also explain the mechanisms of the current economic development of solar technologies and anticipate changes

  2. Placement and efficiency effects on radiative forcing of solar installations

    Energy Technology Data Exchange (ETDEWEB)

    Burg, Brian R.; Ruch, Patrick; Paredes, Stephan; Michel, Bruno, E-mail: bmi@zurich.ibm.com [IBM Research - Zurich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland)

    2015-09-28

    The promise for harnessing solar energy being hampered by cost, triggered efforts to reduce them. As a consequence low-efficiency, low-cost photovoltaics (PV) panels prevail. Conversely, in the traditional energy sector efficiency is extremely important due to the direct costs associated to fuels. This also affects solar energy due to the radiative forcing caused by the dark solar panels. In this paper we extend the concept of energy payback time by including the effect of albedo change, which gives a better assessment of the system sustainability. We present an analysis on the short and medium term climate forcing effects of different solar collectors in Riyadh, Saudi Arabia and demonstrate that efficiency is important to reduce the collector area and cost. This also influences the embodied energy and the global warming potential. We show that a placement of a high concentration photovoltaic thermal solar power station outside of the city using a district cooling system has a double beneficial effect since it improves the solar conversion efficiency and reduces the energy demand for cooling in the city. We also explain the mechanisms of the current economic development of solar technologies and anticipate changes.

  3. Non-Kyoto radiative forcing in long-run greenhouse gas emissions and climate change scenarios

    NARCIS (Netherlands)

    Rose, S.K.; Kriegler, E.; Bibas, R.; Calvin, K.; Popp, A.; van Vuuren, D.P.|info:eu-repo/dai/nl/11522016X; Weyant, J.

    2014-01-01

    Climate policies must consider radiative forcing from Kyoto greenhouse gases, as well as other forcing constituents, such as aerosols and tropospheric ozone that result from air pollutants. Non-Kyoto forcing constituents contribute negative, as well as positive forcing, and overall increases in

  4. Radiative forcing of the desert aerosol at Ouarzazate (Morocco)

    Science.gov (United States)

    Tahiri, Abdelouahid; Diouri, Mohamed

    2018-05-01

    The atmospheric aerosol contributes to the definition of the climate with direct effect, the diffusion and absorption of solar and terrestrial radiations, and indirect, the cloud formation process where aerosols behave as condensation nuclei and alter the optical properties. Satellites and ground-based networks (solar photometers) allow the terrestrial aerosol observation and the determination of impact. Desert aerosol considered among the main types of tropospheric aerosols whose optical property uncertainties are still quite important. The analysis concerns the optical parameters recorded in 2015 at Ouarzazate solar photometric station (AERONET/PHOTONS network, http://aeronet.gsfc.nasa.gov/) close to Saharan zone. The daily average aerosol optical depthτaer at 0.5μm, are relatively high in summer and less degree in spring (from 0.01 to 1.82). Daily average of the Angstrom coefficients α vary between 0.01 and 1.55. The daily average of aerosol radiative forcing at the surface range between -150W/m2 and -10 W/m2 with peaks recorded in summer, characterized locally by large loads of desert aerosol in agreement with the advections of the Southeast of Morocco. Those recorded at the Top of the atmosphere show a variation from -74 W/m2 to +24 W/m2

  5. Radiative flux and forcing parameterization error in aerosol-free clear skies.

    Science.gov (United States)

    Pincus, Robert; Mlawer, Eli J; Oreopoulos, Lazaros; Ackerman, Andrew S; Baek, Sunghye; Brath, Manfred; Buehler, Stefan A; Cady-Pereira, Karen E; Cole, Jason N S; Dufresne, Jean-Louis; Kelley, Maxwell; Li, Jiangnan; Manners, James; Paynter, David J; Roehrig, Romain; Sekiguchi, Miho; Schwarzkopf, Daniel M

    2015-07-16

    Radiation parameterizations in GCMs are more accurate than their predecessorsErrors in estimates of 4 ×CO 2 forcing are large, especially for solar radiationErrors depend on atmospheric state, so global mean error is unknown.

  6. Study of Radiative Forcing of Dust Aerosols and its impact on Climate Characteristics

    KAUST Repository

    Qureshi, Fawwad H

    2012-01-01

    The purpose of following project is to study the effect of dust aerosols on the radiative forcing which is directly related to the surface temperature. A single column radiative convective model is used for simulation purpose. A series

  7. A numerical study of microparticle acoustophoresis driven by acoustic radiation forces and streaming-induced drag forces

    DEFF Research Database (Denmark)

    Muller, Peter Barkholt; Barnkob, Rune; Jensen, Mads Jakob Herring

    2012-01-01

    We present a numerical study of the transient acoustophoretic motion of microparticles suspended in a liquid-filled microchannel and driven by the acoustic forces arising from an imposed standing ultrasound wave: the acoustic radiation force from the scattering of sound waves on the particles...

  8. Aerosol optical properties and direct radiative forcing at Taihu.

    Science.gov (United States)

    Lü, Rui; Yu, Xingna; Jia, Hailing; Xiao, Sihan

    2017-09-01

    Ground-based characteristics (optical, type, size, and radiative properties) of aerosols measured between 2005 and 2012 were investigated over the Taihu rim region, which encompasses the cities of Shanghai, Suzhou, Wuxi, and Changzhou. The aerosol optical depth (AOD) showed a distinct seasonal variation with the highest value in summer and the lowest AOD in winter. There was broadest frequency distribution with a multimodal structure in summer. The Ångström exponent (AE) showed high values during spring; the relative frequency of AE in the range of 0-0.8 was 5-10 times greater than that of other seasons. The samples with high AOD 440 and low AE 440-870 were mainly observed in spring, which is attributed to the relative abundance of coarse particles. The monthly aerosol volume size distributions presented a bimodal structure (fine and coarse modes). The coarse mode was dominant during spring, while the fine mode was predominant in other seasons. The main aerosol type over Taihu during all the seasons was the mixed small-particle category, followed by the urban/industrial category. The minimum single scattering albedo (SSA) occurred in winter, suggesting that atmosphere aerosol had a higher absorption. All monthly averaged asymmetry factors (ASY) had positive values and no distinct seasonal variation. Both high real (Re) and imaginary (Im) parts of the refractive index occurred in winter. The atmospheric warming effect of aerosol was more significant in winter compared with other seasons, with the averaged atmosphere aerosol radiative forcing (ARF) and the corresponding atmospheric heating rate up to +69.46  W·m -2 and 1.95  K·day -1 , respectively. There existed a significant positive correlation between AOD and ARF (absolute value), and the correlation coefficients (r) exceeded 0.86 in each season with maximum r in summer. Along with the increasing of the SSA, the aerosol radiative forcing efficiency (absolute value) showed a decreasing trend at the

  9. Aerosol Direct Radiative Forcing and Forcing Efficiencies at Surface from the shortwave Irradiance Measurements in Abu Dhabi, UAE

    Science.gov (United States)

    Beegum S, N.; Ben Romdhane, H.; Ghedira, H.

    2013-12-01

    Atmospheric aerosols are known to affect the radiation balance of the Earth-Atmospheric system directly by scattering and absorbing the solar and terrestrial radiation, and indirectly by affecting the lifetime and albedo of the clouds. Continuous and simultaneous measurements of short wave global irradiance in combination with synchronous spectral aerosol optical depth (AOD) measurements (from 340 nm to 1640 nm in 8 channels), for a period of 1 year from June 2012 to May 2013, were used for the determination of the surface direct aerosol radiative forcing and forcing efficiencies under cloud free conditions in Abu Dhabi (24.42°N, 54.61o E, 7m MSL), a coastal location in United Arab Emirates (UAE) in the Arabian Peninsula. The Rotating Shadow band Pyranometer (RSP, LI-COR) was used for the irradiance measurements (in the spectral region 400-1100 nm), whereas the AOD measurements were carried out using CIMEL Sunphotometer (CE 318-2, under AERONET program). The differential method, which is neither sensitive to calibration uncertainties nor model assumptions, has been employed for estimating forcing efficiencies from the changes in the measured fluxes. The forcing efficiency, which quantifies the net change in irradiance per unit change in AOD, is an appropriate parameter for the characterization of the aerosol radiative effects even if the microphysical and optical properties of the aerosols are not completely understood. The corresponding forcing values were estimated from the forcing efficiencies. The estimated radiative forcing and forcing efficiencies exhibited strong monthly variations. The forcing efficiencies (absolute magnitudes) were highest during March, and showed continuous decrease thereafter to reach the lowest value during September. In contrast, the forcing followed a slightly different pattern of variability, with the highest solar dimming during April ( -60 W m-2) and the minimum during February ( -20 W m-2). The results indicate that the aerosol

  10. [Radiative and hygienic certification in Armed Forces, problems of its implementation and ways of perfection].

    Science.gov (United States)

    Rusakov, V N; Cherkashin, A V; Shishkanov, A P; Ian'shin, L A; Gracheva, T N

    2010-12-01

    Radiative and hygienic passportization is one of the most actual pattern of socio and hygienic monitoring in Armed Forces. Radiative and hygienic passport is the main document which characterizes the safety control in military unit and uses the sources of ionizing radiation. Sanitary and epidemiologic institutions were imputed to control the formation of radiative and hygienic passports, analysis and generalization of its data, formation of conclusions about the condition of radiation security in the military units. According to radiative and hygienic passportization, which took place in 2009, the radiation security in the Armed Forces and organizations is satisfactory, but there are some problems of providing of radiation security of personnel under the professional and medical radiation. The salvation of its problems requires the effective work of official functionary of radiac object and institutions of state sanitary and epidemiological supervision in Armed Forces of Russian Federation.

  11. Compression force and radiation dose in the Norwegian Breast Cancer Screening Program

    Energy Technology Data Exchange (ETDEWEB)

    Waade, Gunvor G.; Sanderud, Audun [Department of Life Sciences and Health, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, P.O. 4 St. Olavs Plass, 0130 Oslo (Norway); Hofvind, Solveig, E-mail: solveig.hofvind@kreftregisteret.no [Department of Life Sciences and Health, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, P.O. 4 St. Olavs Plass, 0130 Oslo (Norway); The Cancer Registry of Norway, P.O. 5313 Majorstuen, 0304 Oslo (Norway)

    2017-03-15

    Highlights: • Compression force and radiation dose for 17 951 screening mammograms were analyzed. • Large variations in mean applied compression force between the breast centers. • Limited associations between compression force and radiation dose. - Abstract: Purpose: Compression force is used in mammography to reduce breast thickness and by that decrease radiation dose and improve image quality. There are no evidence-based recommendations regarding the optimal compression force. We analyzed compression force and radiation dose between screening centers in the Norwegian Breast Cancer Screening Program (NBCSP), as a first step towards establishing evidence-based recommendations for compression force. Materials and methods: The study included information from 17 951 randomly selected screening examinations among women screened with equipment from four different venors at fourteen breast centers in the NBCSP, January-March 2014. We analyzed the applied compression force and radiation dose used on craniocaudal (CC) and mediolateral-oblique (MLO) view on left breast, by breast centers and vendors. Results: Mean compression force used in the screening program was 116N (CC: 108N, MLO: 125N). The maximum difference in mean compression force between the centers was 63N for CC and 57N for MLO. Mean radiation dose for each image was 1.09 mGy (CC: 1.04mGy, MLO: 1.14mGy), varying from 0.55 mGy to 1.31 mGy between the centers. Compression force alone had a negligible impact on radiation dose (r{sup 2} = 0.8%, p = < 0.001). Conclusion: We observed substantial variations in mean compression forces between the breast centers. Breast characteristics and differences in automated exposure control between vendors might explain the low association between compression force and radiation dose. Further knowledge about different automated exposure controls and the impact of compression force on dose and image quality is needed to establish individualised and evidence

  12. Quantifying immediate radiative forcing by black carbon and organic matter with the Specific Forcing Pulse

    Directory of Open Access Journals (Sweden)

    T. C. Bond

    2011-02-01

    12 additional models. We outline a framework for combining a large number of simple models with a smaller number of enhanced models that have greater complexity. Adjustments for black carbon internal mixing and for regional variability are discussed. Emitting regions with more deep convection have greater model diversity. Our best estimate of global-mean SFP is +1.03 ± 0.52 GJ g−1 for direct atmosphere forcing of black carbon, +1.15 ± 0.53 GJ g−1 for black carbon including direct and cryosphere forcing, and −0.064 (−0.02, −0.13 GJ g−1 for organic matter. These values depend on the region and timing of emission. The lowest OM:BC mass ratio required to produce a neutral effect on top-of-atmosphere direct forcing is 15:1 for any region. Any lower ratio results in positive direct forcing. However, important processes, particularly cloud changes that tend toward cooling, have not been included here.

    Global-average SFP for energy-related emissions can be converted to a 100-year GWP of about 740 ± 370 for BC without snow forcing, and 830 ± 440 with snow forcing. 100-year GWP for OM is −46 (−18, −92. Best estimates of atmospheric radiative impact (without snow forcing by black and organic matter are +0.47 ± 0.26 W m−2 and −0.17 (−0.07, −0.35 W m−2 for BC and OM, respectively, assuming total emission rates of 7.4 and 45 Tg yr−1. Anthropogenic forcing is +0.40 ± 0.18 W m−2 and −0.13 (−0.05, −0.25 W m−2 for BC and OM, respectively, assuming anthropogenic emission rates of 6.3 and 32.6 Tg yr−1. Black carbon forcing is only 18% higher than that given by the Intergovernmental Panel on Climate Change (IPCC, although the value presented here includes enhanced absorption due to internal mixing.

  13. Radiative forcing from particle emissions by future supersonic aircraft

    Directory of Open Access Journals (Sweden)

    G. Pitari

    2008-07-01

    Full Text Available In this work we focus on the direct radiative forcing (RF of black carbon (BC and sulphuric acid particles emitted by future supersonic aircraft, as well as on the ozone RF due to changes produced by emissions of both gas species (NOx, H2O and aerosol particles capable of affecting stratospheric ozone chemistry. Heterogeneous chemical reactions on the surface of sulphuric acid stratospheric particles (SSA-SAD are the main link between ozone chemistry and supersonic aircraft emissions of sulphur precursors (SO2 and particles (H2O–H2SO4. Photochemical O3 changes are compared from four independent 3-D atmosphere-chemistry models (ACMs, using as input the perturbation of SSA-SAD calculated in the University of L'Aquila model, which includes on-line a microphysics code for aerosol formation and growth. The ACMs in this study use aircraft emission scenarios for the year 2050 developed by AIRBUS as a part of the EU project SCENIC, assessing options for fleet size, engine technology (NOx emission index, Mach number, range and cruising altitude. From our baseline modeling simulation, the impact of supersonic aircraft on sulphuric acid aerosol and BC mass burdens is 53 and 1.5 μg/m2, respectively, with a direct RF of −11.4 and 4.6 mW/m2 (net RF=−6.8 mW/m2. This paper discusses the similarities and differences amongst the participating models in terms of changes to O3 precursors due to aircraft emissions (NOx, HOx,Clx,Brx and the stratospheric ozone sensitivity to them. In the baseline case, the calculated global ozone change is −0.4 ±0.3 DU, with a net radiative forcing (IR+UV of −2.5± 2 mW/m2. The fraction of this O3-RF attributable to SSA-SAD changes is, however, highly variable among the models, depending on the NOx removal

  14. Global source attribution of sulfate aerosol and its radiative forcing

    Science.gov (United States)

    Yang, Y.; Wang, H.; Smith, S.; Easter, R. C.; Ma, P. L.; Qian, Y.; Li, C.; Yu, H.; Rasch, P. J.

    2017-12-01

    Sulfate is an important aerosol that poses health risks and influences climate. Due to long-range atmospheric transport, local sulfate pollution could result from intercontinental influences, making domestic efforts of improving air quality inefficient. Accurate understanding of source attribution of sulfate and its radiative forcing is important for both regional air quality improvement and global climate mitigation. In this study, for the first time, a sulfur source-tagging capability is implemented in the Community Atmosphere Model (CAM5) to quantify the global source-receptor relationships of sulfate and its direct and indirect radiative forcing (DRF and IRF). Near-surface sulfate concentrations are mostly contributed by local emissions in regions with high emissions, while over regions with relatively low SO2 emissions, the near-surface sulfate is primarily attributed to non-local sources from long-range transport. The export of SO2 and sulfate from Europe contributes 20% of sulfate concentrations over North Africa, Russia and Central Asia. Sources from the Middle East account for 20% of sulfate over North Africa, Southern Africa and Central Asia in winter and autumn, and 20% over South Asia in spring. East Asia accounts for about 50% of sulfate over Southeast Asia in winter and autumn, 15% over Russia in summer, and 10% over North America in spring. South Asia contributes to 25% of sulfate over Southeast Asia in spring. Lifetime of aerosols, together with regional export, is found to determine regional air quality. The simulated global total sulfate DRF is -0.42 W m-2, with 75% contributed by anthropogenic sulfate and 25% contributed by natural sulfate. In the Southern Hemisphere tropics, dimethyl sulfide (DMS) contributes the most to the total DRF. East Asia has the largest contribution of 20-30% over the Northern Hemisphere mid- and high-latitudes. A 20% perturbation of sulfate and its precursor emissions gives a sulfate IRF of -0.44 W m-2. DMS has the

  15. Sulfate Aerosol in the Arctic: Source Attribution and Radiative Forcing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yang [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Wang, Hailong [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Smith, Steven J. [Joint Global Change Research Institute, Pacific Northwest National Laboratory, College Park MD USA; Easter, Richard C. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Rasch, Philip J. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA

    2018-02-08

    Source attributions of Arctic sulfate and its direct radiative effect for 2010–2014 are quantified in this study using the Community Earth System Model (CESM) equipped with an explicit sulfur source-tagging technique. Regions that have high emissions and/or are near/within the Arctic present relatively large contributions to Arctic sulfate burden, with the largest contribution from sources in East Asia (27%). East Asia and South Asia together have the largest contributions to Arctic sulfate concentrations at 9–12 km, whereas sources within or near the Arctic account largely below 2 km. For remote sources with strong emissions, their contributions to Arctic sulfate burden are primarily driven by meteorology, while contributions of sources within or near the Arctic are dominated by their emission strength. The sulfate direct radiative effect (DRE) is –0.080 W m-2 at the Arctic surface, offsetting the net warming effect from the combination of in-snow heating and DRE cooling from black carbon. East Asia, Arctic local and Russia/Belarus/Ukraine sources contribute –0.017, –0.016 and –0.014 W m-2, respectively, to Arctic sulfate DRE. A 20% reduction in anthropogenic SO2 emissions leads to a net increase of +0.013 W m-2 forcing at the Arctic surface. These results indicate that a joint reduction in BC emissions could prevent possible Arctic warming from future reductions in SO2 emissions. Sulfate DRE efficiency calculations suggest that short transport pathways together with meteorology favoring long sulfate lifetimes make certain sources more efficient in influencing the Arctic sulfate DRE.

  16. Direct weakening of tropical circulations from masked CO2 radiative forcing.

    Science.gov (United States)

    Merlis, Timothy M

    2015-10-27

    Climate models robustly simulate weakened mean circulations of the tropical atmosphere in direct response to increased carbon dioxide (CO2). The direct response to CO2, defined by the response to radiative forcing in the absence of changes in sea surface temperature, affects tropical precipitation and tropical cyclone genesis, and these changes have been tied to the weakening of the mean tropical circulation. The mechanism underlying this direct CO2-forced circulation change has not been elucidated. Here, I demonstrate that this circulation weakening results from spatial structure in CO2's radiative forcing. In regions of ascending circulation, such as the intertropical convergence zone, the CO2 radiative forcing is reduced, or "masked," by deep-convective clouds and high humidity; in subsiding regions, such as the subtropics, the CO2 radiative forcing is larger because the atmosphere is drier and deep-convective clouds are infrequent. The spatial structure of the radiative forcing reduces the need for the atmosphere to transport energy. This, in turn, weakens the mass overturning of the tropical circulation. The previously unidentified mechanism is demonstrated in a hierarchy of atmospheric general circulation model simulations with altered radiative transfer to suppress the cloud masking of the radiative forcing. The mechanism depends on the climatological distribution of clouds and humidity, rather than uncertain changes in these quantities. Masked radiative forcing thereby offers an explanation for the robustness of the direct circulation weakening under increased CO2.

  17. Mineral Dust Instantaneous Radiative Forcing in the Arctic

    Science.gov (United States)

    Kylling, A.; Groot Zwaaftink, C. D.; Stohl, A.

    2018-05-01

    Mineral dust sources at high and low latitudes contribute to atmospheric dust loads and dust deposition in the Arctic. With dust load estimates from Groot Zwaaftink et al. (https://doi.org/10.1002/2016JD025482), we quantify the mineral dust instantaneous radiative forcing (IRF) in the Arctic for the year 2012. The annual-mean top of the atmosphere IRF is 0.225 W/m2, with the largest contributions from dust transported from Asia south of 60°N and Africa. High-latitude (>60°N) dust sources contribute about 39% to top of the atmosphere IRF and have a larger impact (1 to 2 orders of magnitude) on IRF per emitted kilogram of dust than low-latitude sources. Mineral dust deposited on snow accounts for nearly all of the bottom of the atmosphere IRF of 0.135 W/m2. More than half of the bottom of the atmosphere IRF is caused by dust from high-latitude sources, indicating substantial regional climate impacts rarely accounted for in current climate models.

  18. Response of air stagnation frequency to anthropogenically enhanced radiative forcing

    International Nuclear Information System (INIS)

    Horton, Daniel E; Diffenbaugh, Noah S; Harshvardhan

    2012-01-01

    Stagnant atmospheric conditions can lead to hazardous air quality by allowing ozone and particulate matter to accumulate and persist in the near-surface environment. By changing atmospheric circulation and precipitation patterns, global warming could alter the meteorological factors that regulate air stagnation frequency. We analyze the response of the National Climatic Data Center (NCDC) air stagnation index (ASI) to anthropogenically enhanced radiative forcing using global climate model projections of late-21st century climate change (SRESA1B scenario). Our results indicate that the atmospheric conditions over the highly populated, highly industrialized regions of the eastern United States, Mediterranean Europe, and eastern China are particularly sensitive to global warming, with the occurrence of stagnant conditions projected to increase by 12–25% relative to late-20th century stagnation frequencies (3–18 + days yr −1 ). Changes in the position/strength of the polar jet, in the occurrence of light surface winds, and in the number of precipitation-free days all contribute to more frequent late-21st century air mass stagnation over these high-population regions. In addition, we find substantial inter-model spread in the simulated response of stagnation conditions over some regions using either native or bias corrected global climate model simulations, suggesting that changes in the atmospheric circulation and/or the distribution of precipitation represent important sources of uncertainty in the response of air quality to global warming. (letter)

  19. Atmospheric radiation measurement: A program for improving radiative forcing and feedback in general circulation models

    International Nuclear Information System (INIS)

    Patrinos, A.A.; Renne, D.S.; Stokes, G.M.; Ellingson, R.G.

    1991-01-01

    The Atmospheric Radiation Measurement (ARM) Program is a key element of the Department of Energy's (DOE's) global change research strategy. ARM represents a long-term commitment to conduct comprehensive studies of the spectral atmospheric radiative energy balance profile for a wide range of cloud conditions and surface types, and to develop the knowledge necessary to improve parameterizations of radiative processes under various cloud regimes for use in general circulation models (GCMs) and related models. The importance of the ARM program is a apparent from the results of model assessments of the impact on global climate change. Recent studies suggest that radiatively active trace gas emissions caused by human activity can lead to a global warming of 1.5 to 4.5 degrees Celsius and to important changes in water availability during the next century (Cess, et al. 1989). These broad-scale changes can be even more significant at regional levels, where large shifts in temperature and precipitation patterns are shown to occur. However, these analyses also indicate that considerable uncertainty exists in these estimates, with the manner in which cloud radiative processes are parameterized among the most significant uncertainty. Thus, although the findings have significant policy implications in assessment of global and regional climate change, their uncertainties greatly influence the policy debate. ARM's highly focused observational and analytical research is intended to accelerate improvements and reduce key uncertainties associated with the way in which GCMs treat cloud cover and cloud characteristics and the resulting radiative forcing. This paper summarizes the scientific context for ARM, ARM's experimental approach, and recent activities within the ARM program

  20. Radiation closure and diurnal cycle of the clear-sky dust instantaneous direct radiative forcing over Arabian Peninsula

    KAUST Repository

    Osipov, Sergey

    2015-04-01

    To better quantify radiative effects of dust over the Arabian Peninsula we have developed a standalone column radiation transport model coupled with the Mie calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments are carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18-20 March 2012. Comprehensive ground-based observations and satellite retrievals are used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing are estimated both from the model and from observations. Diurnal cycle of the the shortwave instantaneous dust direct radiative forcing is studied for a range of aerosol and surface characteristics representative for the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing are evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions along with anisotropic aerosol scattering are mostly responsible for diurnal effects. We also discuss estimates of the climatological dust instantaneous direct radiative forcing over land and the Red Sea using two approaches. The first approach is based on the probability density function of the aerosol optical depth, and the second is based on the climatologically average Spinning Enhanced Visible and Infrared Imager (SEVIRI) aerosol optical depth. Results are compared with Geostationary Earth Radiation Budget (GERB) derived top of the atmosphere climatological forcing over the Red Sea.

  1. On radiation forces acting on a transparent nanoparticle in the field of a focused laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Afanas' ev, A A; Rubinov, A N [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus); Gaida, L S; Guzatov, D V; Svistun, A Ch [Yanka Kupala State University of Grodno, Grodno (Belarus)

    2015-10-31

    Radiation forces acting on a transparent spherical nanoparticle in the field of a focused Gaussian laser beam are studied theoretically in the Rayleigh scattering regime. Expressions are derived for the scattering force and Cartesian components of the gradient force. The resultant force acting on a nanoparticle located in the centre of a laser beam is found. The parameters of the focused beam and optical properties of the nanoparticle for which the longitudinal component of the gradient force exceeds the scattering force are determined. Characteristics of the transverse gradient force are discussed. (nanophotonics)

  2. Winds from accretion disks driven by the radiation and magnetocentrifugal force

    OpenAIRE

    Proga, D.

    2000-01-01

    We study the 2-D, time-dependent hydrodynamics of radiation-driven winds from luminous accretion disks threaded by a strong, large-scale, ordered magnetic field. The radiation force is due to spectral lines and is calculated using a generalized multidimensional formulation of the Sobolev approximation. The effects of the magnetic field are approximated by adding a force that emulates a magnetocentrifugal force. Our approach allows us to calculate disk winds when the magnetic field controls th...

  3. Radiation closure and diurnal cycle of the clear-sky dust instantaneous direct radiative forcing over Arabian Peninsula

    KAUST Repository

    Osipov, Sergey; Stenchikov, Georgiy L.; Brindley,  Helen; Banks,  Jamie

    2015-01-01

    Spinning Enhanced Visible and Infrared Imager (SEVIRI) aerosol optical depth. Results are compared with Geostationary Earth Radiation Budget (GERB) derived top of the atmosphere climatological forcing over the Red Sea.

  4. Discussion on some issues for near surface disposal of L/I LW sandy soil

    International Nuclear Information System (INIS)

    Yu Mingde

    2006-01-01

    It is possible that very low level waste (VLLW) is defined from among LLW and disposed of through a simple/easy engineering method. Enhancing the barrier-function of buffer/backfill material will be favorable in a long-term way for controlling long-lived α-nuclides in near field. Designing the trench cover must suit measures to local conditions and lay stress on the key points. For long-term and efficacious supervision on L/I LW disposal facilities, it is very important to change managing ideologies. (authors)

  5. Design of two-DMD based zoom MW and LW dual-band IRSP using pixel fusion

    Science.gov (United States)

    Pan, Yue; Xu, Xiping; Qiao, Yang

    2018-06-01

    In order to test the anti-jamming ability of mid-wave infrared (MWIR) and long-wave infrared (LWIR) dual-band imaging system, a zoom mid-wave (MW) and long-wave (LW) dual-band infrared scene projector (IRSP) based on two-digital micro-mirror device (DMD) was designed by using a projection method of pixel fusion. Two illumination systems, which illuminate the two DMDs directly with Kohler telecentric beam respectively, were combined with projection system by a spatial layout way. The distances of projection entrance pupil and illumination exit pupil were also analyzed separately. MWIR and LWIR virtual scenes were generated respectively by two DMDs and fused by a dichroic beam combiner (DBC), resulting in two radiation distributions in projected image. The optical performance of each component was evaluated by ray tracing simulations. Apparent temperature and image contrast were demonstrated by imaging experiments. On the basis of test and simulation results, the aberrations of optical system were well corrected, and the quality of projected image meets test requirements.

  6. Acoustic radiation force on cylindrical shells in a plane standing wave

    International Nuclear Information System (INIS)

    Mitri, F G

    2005-01-01

    In this paper, the radiation force per length resulting from a plane standing wave incident on an infinitely long cylindrical shell is computed. The cases of elastic and viscoelastic shells immersed in ideal (non-viscous) fluids are considered with particular emphasis on their thickness and the content of their interior hollow spaces. Numerical calculations of the radiation force function Y st are performed. The fluid-loading effect on the radiation force function curves is analysed as well. The results show several features quite different when the interior hollow space is changed from air to water. Moreover, the theory developed here is more general since it includes the results on cylinders

  7. The Effect of Non-Lambertian Surface Reflectance on Aerosol Radiative Forcing

    Energy Technology Data Exchange (ETDEWEB)

    Ricchiazzi, P.; O' Hirok, W.; Gautier, C.

    2005-03-18

    Surface reflectance is an important factor in determining the strength of aerosol radiative forcing. Previous studies of radiative forcing assumed that the reflected surface radiance is isotropic and does not depend on incident illumination angle. This Lambertian reflection model is not a very good descriptor of reflectance from real land and ocean surfaces. In this study we present computational results for the seasonal average of short and long wave aerosol radiative forcing at the top of the atmosphere and at the surface. The effect of the Lambertian assumption is found through comparison with calculations using a more detailed bi-direction reflectance distribution function (BRDF).

  8. Resolution of the uncertainties in the radiative forcing of HFC-134a

    International Nuclear Information System (INIS)

    Forster, Piers M. de F; Burkholder, J.B.; Clerbaux, C.; Coheur, P.F.; Dutta, M.; Gohar, L.K.; Hurley, M.D.; Myhre, G.; Portmann, R.W.; Shine, K.P.; Wallington, T.J.; Wuebbles, D.

    2005-01-01

    HFC-134a (CF 3 CH 2 F) is the most rapidly growing hydrofluorocarbon in terms of atmospheric abundance. It is currently used in a large number of household refrigerators and air-conditioning systems and its concentration in the atmosphere is forecast to increase substantially over the next 50-100 years. Previous estimates of its radiative forcing per unit concentration have differed significantly ∼25%. This paper uses a two-step approach to resolve this discrepancy. In the first step six independent absorption cross section datasets are analysed. We find that, for the integrated cross section in the spectral bands that contribute most to the radiative forcing, the differences between the various datasets are typically smaller than 5% and that the dependence on pressure and temperature is not significant. A 'recommended' HFC-134a infrared absorption spectrum was obtained based on the average band intensities of the strongest bands. In the second step, the 'recommended' HFC-134a spectrum was used in six different radiative transfer models to calculate the HFC-134a radiative forcing efficiency. The clear-sky instantaneous radiative forcing, using a single global and annual mean profile, differed by 8%, between the 6 models, and the latitudinally-resolved adjusted cloudy sky radiative forcing estimates differed by a similar amount. We calculate that the radiative forcing efficiency of HFC-134a is 0.16+/-0.02Wm -2 ppbv -1

  9. Key drivers of ozone change and its radiative forcing over the 21st century

    Science.gov (United States)

    Iglesias-Suarez, Fernando; Kinnison, Douglas E.; Rap, Alexandru; Maycock, Amanda C.; Wild, Oliver; Young, Paul J.

    2018-05-01

    Over the 21st century changes in both tropospheric and stratospheric ozone are likely to have important consequences for the Earth's radiative balance. In this study, we investigate the radiative forcing from future ozone changes using the Community Earth System Model (CESM1), with the Whole Atmosphere Community Climate Model (WACCM), and including fully coupled radiation and chemistry schemes. Using year 2100 conditions from the Representative Concentration Pathway 8.5 (RCP8.5) scenario, we quantify the individual contributions to ozone radiative forcing of (1) climate change, (2) reduced concentrations of ozone depleting substances (ODSs), and (3) methane increases. We calculate future ozone radiative forcings and their standard error (SE; associated with inter-annual variability of ozone) relative to year 2000 of (1) 33 ± 104 m Wm-2, (2) 163 ± 109 m Wm-2, and (3) 238 ± 113 m Wm-2 due to climate change, ODSs, and methane, respectively. Our best estimate of net ozone forcing in this set of simulations is 430 ± 130 m Wm-2 relative to year 2000 and 760 ± 230 m Wm-2 relative to year 1750, with the 95 % confidence interval given by ±30 %. We find that the overall long-term tropospheric ozone forcing from methane chemistry-climate feedbacks related to OH and methane lifetime is relatively small (46 m Wm-2). Ozone radiative forcing associated with climate change and stratospheric ozone recovery are robust with regard to background climate conditions, even though the ozone response is sensitive to both changes in atmospheric composition and climate. Changes in stratospheric-produced ozone account for ˜ 50 % of the overall radiative forcing for the 2000-2100 period in this set of simulations, highlighting the key role of the stratosphere in determining future ozone radiative forcing.

  10. Experimental verification of theoretical equations for acoustic radiation force on compressible spherical particles in traveling waves

    Science.gov (United States)

    Johnson, Kennita A.; Vormohr, Hannah R.; Doinikov, Alexander A.; Bouakaz, Ayache; Shields, C. Wyatt; López, Gabriel P.; Dayton, Paul A.

    2016-05-01

    Acoustophoresis uses acoustic radiation force to remotely manipulate particles suspended in a host fluid for many scientific, technological, and medical applications, such as acoustic levitation, acoustic coagulation, contrast ultrasound imaging, ultrasound-assisted drug delivery, etc. To estimate the magnitude of acoustic radiation forces, equations derived for an inviscid host fluid are commonly used. However, there are theoretical predictions that, in the case of a traveling wave, viscous effects can dramatically change the magnitude of acoustic radiation forces, which make the equations obtained for an inviscid host fluid invalid for proper estimation of acoustic radiation forces. To date, experimental verification of these predictions has not been published. Experimental measurements of viscous effects on acoustic radiation forces in a traveling wave were conducted using a confocal optical and acoustic system and values were compared with available theories. Our results show that, even in a low-viscosity fluid such as water, the magnitude of acoustic radiation forces is increased manyfold by viscous effects in comparison with what follows from the equations derived for an inviscid fluid.

  11. Calculation of the radiation force on a cylinder in a standing wave acoustic field

    Energy Technology Data Exchange (ETDEWEB)

    Haydock, David [Unilever R and D Colworth, Sharnbrook, Bedford MK44 1LQ (United Kingdom); Department of Physics, Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

    2005-04-15

    We present a new calculation of the radiation force on a cylinder in a standing wave acoustic field. We use the formula to calculate the force on a cylinder which is free to move in the field and one which is fixed in space.

  12. Calculation of the radiation force on a cylinder in a standing wave acoustic field

    International Nuclear Information System (INIS)

    Haydock, David

    2005-01-01

    We present a new calculation of the radiation force on a cylinder in a standing wave acoustic field. We use the formula to calculate the force on a cylinder which is free to move in the field and one which is fixed in space

  13. Remote sensing of aerosol characteristics and radiative forcing in Pakistan

    International Nuclear Information System (INIS)

    Alam, K.

    2011-01-01

    This thesis investigates the aerosol characteristics over different cities of Pakistan through satellite borne sensors, namely the Total Ozone Mapping Spectrometer (TOMS), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Multi-angle Imaging Spectroradiometer (MISR), and ground-based instruments such as Aerosol Robotic Network (AERONET) and GRIMM 1.109 dust monitor. A Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used for trajectory analysis in order to visualize the origins of air masses and understand the spatio-temporal variability of aerosol concentrations. An assessment of seasonal variability in aerosol optical depth (AOD) for industrial, urban, semi-urban, rural, and semi-arid areas revealed maximum AOD values during summer over all the areas under investigation. The correlation between AERONET and MODIS/MISR AODs during 2007 was also analyzed for Karachi and Lahore. The correlation coefficient for Karachi was found to be relatively high between AERONET and MISR and lower between AERONET and MODIS. In contrast, the correlation coefficient for Lahore was higher between AERONET and MODIS than between AERONET and MISR. The results suggest that the MISR sensor provides better AOD estimates near the ocean while AOD estimates from the MODIS sensor are better over terrestrial regions (especially over vegetated surfaces). The assessment of aerosol optical properties and aerosol radiative forcing (ARF) through the ground-based Aerosol Robotic Network (AERONET) over Lahore and Karachi has also been investigated in this study. The monthly mean of AOD at 500 nm over Lahore and Karachi ranges from 0.39 to 0.76, and the monthly mean Angstrom Exponent ranges from 0.29 to 1.22. The relationship between the Absorption Angstrom Exponent and the Extinction Angstrom Exponent provided an indication of relative proportions of urban-industrial and mineral dust aerosols over both sites. The single scattering albedo (SSA) ranged from 0

  14. Cloud forming properties of ambient aerosol in the Netherlands and resultant shortwave radiative forcing of climate

    NARCIS (Netherlands)

    Khlystov, A.

    1998-01-01

    This thesis discusses properties of ambient aerosols in the Netherlands which are controlling the magnitude of the local aerosol radiative forcing. Anthropogenic aerosols influence climate by changing the radiative transfer through the atmosphere via two effects, one is direct and a second

  15. Acoustofluidics: Theory and simulation of streaming and radiation forces at ultrasound resonances in microfluidic devices

    DEFF Research Database (Denmark)

    Bruus, Henrik

    2009-01-01

    fields, which are directly related to the acoustic radiation force on single particles and to the acoustic streaming of the liquid. For the radiation pressure effects, there is good agreement between theory and simulation, while the numeric results for the acoustic streaming effects are more problematic...

  16. Satellite-derived aerosol radiative forcing from the 2004 British Columbia wildfires

    Science.gov (United States)

    Guo, Song; Leighton, H.

    2008-01-01

    The British Columbia wildfires of 2004 was one of the largest wildfire events in the last ten years in Canada. Both the shortwave and longwave smoke aerosol radiative forcing at the top-of-atmosphere (TOA) are investigated using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth's Radiant Energy System (CERES) instruments. Relationships between the radiative forcing fluxes (??F) and wildfire aerosol optical thickness (AOT) at 0.55 ??m (??0.55) are deduced for both noontime instantaneous forcing and diurnally averaged forcing. The noontime averaged instantaneous shortwave and longwave smoke aerosol radiative forcing at the TOA are 45.8??27.5 W m-2 and -12.6??6.9 W m-2, respectively for a selected study area between 62??N and 68??N in latitude and 125??W and 145??W in longitude over three mainly clear-sky days (23-25 June). The derived diurnally averaged smoke aerosol shortwave radiative forcing is 19.9??12.1 W m-2 for a mean ??0.55 of 1.88??0.71 over the same time period. The derived ??F-?? relationship can be implemented in the radiation scheme used in regional climate models to assess the effect of wildfire aerosols.

  17. Final Report: 06-LW-013, Nuclear Physics the Monte Carlo Way

    International Nuclear Information System (INIS)

    Ormand, W.E.

    2009-01-01

    This is document reports the progress and accomplishments achieved in 2006-2007 with LDRD funding under the proposal 06-LW-013, 'Nuclear Physics the Monte Carlo Way'. The project was a theoretical study to explore a novel approach to dealing with a persistent problem in Monte Carlo approaches to quantum many-body systems. The goal was to implement a solution to the notorious 'sign-problem', which if successful, would permit, for the first time, exact solutions to quantum many-body systems that cannot be addressed with other methods. In this document, we outline the progress and accomplishments achieved during FY2006-2007 with LDRD funding in the proposal 06-LW-013, 'Nuclear Physics the Monte Carlo Way'. This project was funded under the Lab Wide LDRD competition at Lawrence Livermore National Laboratory. The primary objective of this project was to test the feasibility of implementing a novel approach to solving the generic quantum many-body problem, which is one of the most important problems being addressed in theoretical physics today. Instead of traditional methods based matrix diagonalization, this proposal focused a Monte Carlo method. The principal difficulty with Monte Carlo methods, is the so-called 'sign problem'. The sign problem, which will discussed in some detail later, is endemic to Monte Carlo approaches to the quantum many-body problem, and is the principal reason that they have not been completely successful in the past. Here, we outline our research in the 'shifted-contour method' applied the Auxiliary Field Monte Carlo (AFMC) method

  18. ENSO surface longwave radiation forcing over the tropical Pacific

    Directory of Open Access Journals (Sweden)

    K. G. Pavlakis

    2007-01-01

    Full Text Available We have studied the spatial and temporal variation of the surface longwave radiation (downwelling and net over a 21-year period in the tropical and subtropical Pacific Ocean (40 S–40 N, 90 E–75 W. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database and reanalysis data from NCEP/NCAR (acronyms explained in main text, for the key atmospheric and surface input parameters. An excellent correlation was found between the downwelling longwave radiation (DLR anomaly and the Niño-3.4 index time-series, over the Niño-3.4 region located in the central Pacific. A high anti-correlation was also found over the western Pacific (15–0 S, 105–130 E. There is convincing evidence that the time series of the mean downwelling longwave radiation anomaly in the western Pacific precedes that in the Niño-3.4 region by 3–4 months. Thus, the downwelling longwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to asses whether or not El Niño or La Niña conditions prevail. Over the Niño-3.4 region, the mean DLR anomaly values range from +20 Wm−2 during El Niño episodes to −20 Wm−2 during La Niña events, while over the western Pacific (15–0 S, 105–130 E these values range from −15 Wm−2 to +10 Wm−2, respectively. The long- term average (1984–2004 distribution of the net downwelling longwave radiation at the surface over the tropical and subtropical Pacific for the three month period November-December-January shows a net thermal cooling of the ocean surface. When El Niño conditions prevail, the thermal radiative cooling in the central and south-eastern tropical Pacific becomes weaker by 10 Wm−2 south of the equator in the central Pacific (7–0 S, 160–120 W for the three-month period of NDJ, because the DLR increase is larger than the increase in surface thermal emission. In contrast, the

  19. Interagency task force on the health effects of ionizing radiation. final report

    International Nuclear Information System (INIS)

    1979-06-01

    This is the final report of the task force and incorporates the findings and recommendations of six smaller work groups, each with a more specific focus; i.e., science, privacy, care and benefits, exposure reduction, public information, and institutional arrangements. A research agenda that could provide some answers to questions about the effects of low-level radiation is proposed, along with recommendations to facilitate research. A public information program is outlined. Recommendations are advanced to improve systems that deliver care and benefits to those who may have been injured by exposure to radiation, and proposals for steps that might reduce unnecessary radiation exposure in the future are identified. The task force also recommends measures to institutionalize the interagency cooperation that characterized the task force. Three tables and one figure show the collective estimates of the U.S. general population, Federal research financing, cancer linked to radiation in particular populations, and a general dose-response model

  20. Study of Radiative Forcing of Dust Aerosols and its impact on Climate Characteristics

    KAUST Repository

    Qureshi, Fawwad H

    2012-12-01

    The purpose of following project is to study the effect of dust aerosols on the radiative forcing which is directly related to the surface temperature. A single column radiative convective model is used for simulation purpose. A series of simulations have been performed by varying the amount of dust aerosols present in the atmosphere to study the trends in ground temperature, heating rate and radiative forcing for both its longwave and shortwave components. A case study for dust storm is also performed as dust storms are common in Arabian Peninsula. A sensitivity analyses is also performed to study the relationship of surface temperature minimum and maximum against aerosol concentration, single scattering albedo and asymmetry factor. These analyses are performed to get more insight into the role of dust aerosols on radiative forcing.

  1. On the contribution of circumferential resonance modes in acoustic radiation force experienced by cylindrical shells

    Science.gov (United States)

    Rajabi, Majid; Behzad, Mehdi

    2014-10-01

    A body insonified by a constant (time-varying) intensity sound field is known to experience a steady (oscillatory) force that is called the steady-state (dynamic) acoustic radiation force. Using the classical resonance scattering theorem (RST) which suggests the scattered field as a superposition of a resonance field and a background (non-resonance) component, we show that the radiation force acting on a cylindrical shell may be synthesized as a composition of three components: background part, resonance part and their interaction. The background component reveals the pure geometrical reflection effects and illustrates a regular behavior with respect to frequency, while the others demonstrate a singular behavior near the resonance frequencies. The results illustrate that the resonance effects associated to partial waves can be isolated by the subtraction of the background component from the total (steady-state or dynamic) radiation force function (i.e., residue component). In the case of steady-state radiation force, the components are exerted on the body as static forces. For the case of oscillatory amplitude excitation, the components are exerted at the modulation frequency with frequency-dependant phase shifts. The results demonstrate the dominant contribution of the non-resonance component of dynamic radiation force at high frequencies with respect to the residue component, which offers the potential application of ultrasound stimulated vibro-acoustic spectroscopy technique in low frequency resonance spectroscopy purposes. Furthermore, the proposed formulation may be useful essentially due to its intrinsic value in physical acoustics. In addition, it may unveil the contribution of resonance modes in the dynamic radiation force experienced by the cylindrical objects and its underlying physics.

  2. Drift forces on vacancies and interstitials in alloys with radiation-induced segregation

    International Nuclear Information System (INIS)

    Wolfer, W.G.

    1983-01-01

    Radiation-induced segregation in alloys leads to compositional gradients around point defect sinks such as voids and dislocations. These compositional gradients in turn affect the drift forces on both interstitials and vacancies and thereby modify the bias. Linear irreversible thermodynamics is employed to derive the total drift force on interstitials and vacancies in substitutional binary alloys. The obtained results are evaluated for binary Fe-Ni alloys. It is shown that radiation-induced segregation produces new drift forces which can be of the same order of magnitude as the stress-induced drift force produced by edge dislocations in an alloy with uniform composition. Hence, segregation results in a significant modification of the bias for void nucleation and swelling. The additional drift forces on interstitials and vacancies are due to the compositional dependence of the formation and migration energies; due to the dependence of the point defect's strain energy on the local elastic properties; due to a coherency strain field caused by lattice parameter variations; and finally due to the Kirkendall force produced by the difference in tracer mobilities. Estimates of these forces given for Fe-Ni alloys indicate that the Kirkendall force is small compared to the other segregation-induced forces on interstitials. In contrast, the Kirkendall force seems to be the dominant one for vacancies. (orig.)

  3. Monsoon sensitivity to aerosol direct radiative forcing in the ...

    Indian Academy of Sciences (India)

    to the total, scattering aerosols and black carbon aerosols. ... acts as an internal damping mechanism spinning down the regional hydrological cycle and leading to sig- ... tion and emission of longwave radiation. ... effect of aerosols over India, where the emission of .... that aerosol effects on monsoon water cycle dynam-.

  4. The Use of Remote Sensing to Resolve the Aerosol Radiative Forcing

    Science.gov (United States)

    Kaufman, Y. J.; Tanre, D.; Remer, Lorraine

    1999-01-01

    Satellites are used for remote sensing of aerosol optical thickness and optical properties in order to derive the aerosol direct and indirect radiative forcing of climate. Accuracy of the derived aerosol optical thickness is used as a measure of the accuracy in deriving the aerosol radiative forcing. Several questions can be asked to challenge this concept. Is the accuracy of the satellite-derived aerosol direct forcing limited to the accuracy of the measured optical thickness? What are the spectral bands needed to derive the total aerosol forcing? Does most of the direct or indirect aerosol forcing of climate originate from regions with aerosol concentrations that are high enough to be detected from space? What should be the synergism ground-based and space-borne remote sensing to solve the problem? We shall try to answer some of these questions, using AVIRIS airborne measurements and simulations.

  5. Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years.

    Science.gov (United States)

    Joos, Fortunat; Spahni, Renato

    2008-02-05

    The rate of change of climate codetermines the global warming impacts on natural and socioeconomic systems and their capabilities to adapt. Establishing past rates of climate change from temperature proxy data remains difficult given their limited spatiotemporal resolution. In contrast, past greenhouse gas radiative forcing, causing climate to change, is well known from ice cores. We compare rates of change of anthropogenic forcing with rates of natural greenhouse gas forcing since the Last Glacial Maximum and of solar and volcanic forcing of the last millennium. The smoothing of atmospheric variations by the enclosure process of air into ice is computed with a firn diffusion and enclosure model. The 20th century increase in CO(2) and its radiative forcing occurred more than an order of magnitude faster than any sustained change during the past 22,000 years. The average rate of increase in the radiative forcing not just from CO(2) but from the combination of CO(2), CH(4), and N(2)O is larger during the Industrial Era than during any comparable period of at least the past 16,000 years. In addition, the decadal-to-century scale rate of change in anthropogenic forcing is unusually high in the context of the natural forcing variations (solar and volcanoes) of the past millennium. Our analysis implies that global climate change, which is anthropogenic in origin, is progressing at a speed that is unprecedented at least during the last 22,000 years.

  6. Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing using present-day spatiotemporal variability.

    Science.gov (United States)

    Ghan, Steven; Wang, Minghuai; Zhang, Shipeng; Ferrachat, Sylvaine; Gettelman, Andrew; Griesfeller, Jan; Kipling, Zak; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Zhang, Kai

    2016-05-24

    A large number of processes are involved in the chain from emissions of aerosol precursor gases and primary particles to impacts on cloud radiative forcing. Those processes are manifest in a number of relationships that can be expressed as factors dlnX/dlnY driving aerosol effects on cloud radiative forcing. These factors include the relationships between cloud condensation nuclei (CCN) concentration and emissions, droplet number and CCN concentration, cloud fraction and droplet number, cloud optical depth and droplet number, and cloud radiative forcing and cloud optical depth. The relationship between cloud optical depth and droplet number can be further decomposed into the sum of two terms involving the relationship of droplet effective radius and cloud liquid water path with droplet number. These relationships can be constrained using observations of recent spatial and temporal variability of these quantities. However, we are most interested in the radiative forcing since the preindustrial era. Because few relevant measurements are available from that era, relationships from recent variability have been assumed to be applicable to the preindustrial to present-day change. Our analysis of Aerosol Comparisons between Observations and Models (AeroCom) model simulations suggests that estimates of relationships from recent variability are poor constraints on relationships from anthropogenic change for some terms, with even the sign of some relationships differing in many regions. Proxies connecting recent spatial/temporal variability to anthropogenic change, or sustained measurements in regions where emissions have changed, are needed to constrain estimates of anthropogenic aerosol impacts on cloud radiative forcing.

  7. A study of the radiative forcing and global warming potentials of hydrofluorocarbons

    International Nuclear Information System (INIS)

    Zhang Hua; Wu Jinxiu; Lu Peng

    2011-01-01

    We developed a new radiation parameterization of hydrofluorocarbons (HFCs), using the correlated k-distribution method and the high-resolution transmission molecular absorption (HITRAN) 2004 database. We examined the instantaneous and stratospheric adjusted radiative efficiencies of HFCs for clear-sky and all-sky conditions. We also calculated the radiative forcing of HFCs from preindustrial times to the present and for future scenarios given by the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (SRES, in short). Global warming potential and global temperature potential were then examined and compared on the basis of the calculated radiative efficiencies. Finally, we discuss surface temperature changes due to various HFC emissions.

  8. The impact of diurnal variations of air traffic on contrail radiative forcing

    Directory of Open Access Journals (Sweden)

    N. Stuber

    2007-06-01

    Full Text Available We combined high resolution aircraft flight data from the EU Fifth Framework Programme project AERO2k with analysis data from the ECMWF's integrated forecast system to calculate diurnally resolved 3-D contrail cover. We scaled the contrail cover in order to match observational data for the Bakan area (eastern-Atlantic/western-Europe.

    We found that less than 40% of the global distance travelled by aircraft is due to flights during local night time. Yet, due to the cancellation of shortwave and longwave effects during daytime, night time flights contribute a disproportional 60% to the global annual mean forcing. Under clear sky conditions the night flights contribute even more disproportionally at 76%. There are pronounced regional variations in night flying and the associated radiative forcing. Over parts of the North Atlantic flight corridor 75% of air traffic and 84% of the forcing occurs during local night, whereas only 35% of flights are during local night in South-East Asia, yet these contribute 68% of the radiative forcing. In general, regions with a significant local contrail radiative forcing are also regions for which night time flights amount to less than half of the daily total of flights. Therefore, neglecting diurnal variations in air traffic/contrail cover by assuming a diurnal mean contrail cover can over-estimate the global mean radiative forcing by up to 30%.

  9. An exploration in acoustic radiation force experienced by cylindrical shells via resonance scattering theory.

    Science.gov (United States)

    Rajabi, Majid; Behzad, Mehdi

    2014-04-01

    In nonlinear acoustic regime, a body insonified by a sound field is known to experience a steady force that is called the acoustic radiation force (RF). This force is a second-order quantity of the velocity potential function of the ambient medium. Exploiting the sufficiency of linear solution representation of potential function in RF formulation, and following the classical resonance scattering theorem (RST) which suggests the scattered field as a superposition of the resonant field and a background (non-resonant) component, we will show that the radiation force is a composition of three components: background part, resonant part and their interaction. Due to the nonlinearity effects, each part contains the contribution of pure partial waves in addition to their mutual interaction. The numerical results propose the residue component (i.e., subtraction of the background component from the RF) as a good indicator of the contribution of circumferential surface waves in RF. Defining the modal series of radiation force function and its components, it will be shown that within each partial wave, the resonance contribution can be synthesized as the Breit-Wigner form for adequately none-close resonant frequencies. The proposed formulation may be helpful essentially due to its inherent value as a canonical subject in physical acoustics. Furthermore, it may make a tunnel through the circumferential resonance reducing effects on radiation forces. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing.

    Science.gov (United States)

    Kärcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Frömming, Christine

    2010-11-09

    Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model's diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m(2) to 11.6 mW/m(2) for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8-20 mW/m(2) for the air traffic in the year 2000.

  11. ENSO surface shortwave radiation forcing over the tropical Pacific

    Directory of Open Access Journals (Sweden)

    K. G. Pavlakis

    2008-09-01

    Full Text Available We have studied the spatial and temporal variation of the downward shortwave radiation (DSR at the surface of the Earth during ENSO events for a 21-year period over the tropical and subtropical Pacific Ocean (40° S–40° N, 90° E–75° W. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database, reanalysis data from NCEP/NCAR for the key atmospheric and surface input parameters, and aerosol parameters from GADS (acronyms explained in main text. A clear anti-correlation was found between the downward shortwave radiation anomaly (DSR-A time-series, in the region 7° S–5° N 160° E–160° W located west of the Niño-3.4 region, and the Niño-3.4 index time-series. In this region where the highest in absolute value DSR anomalies are observed, the mean DSR anomaly values range from −45 Wm−2 during El Niño episodes to +40 Wm−2 during La Niña events. Within the Niño-3.4 region no significant DSR anomalies are observed during the cold ENSO phase in contrast to the warm ENSO phase. A high correlation was also found over the western Pacific (10° S–5° N, 120–140° E, where the mean DSR anomaly values range from +20 Wm−2 to −20 Wm−2 during El Niño and La Niña episodes, respectively. There is also convincing evidence that the time series of the mean downward shortwave radiation anomaly in the off-equatorial western Pacific region 7–15° N 150–170° E, precedes the Niño-3.4 index time-series by about 7 months and the pattern of this anomaly is indicative of ENSO operating through the mechanism of the western Pacific oscillator. Thus, the downward shortwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to assess whether or not El Niño or La Niña conditions prevail.

  12. Nonlinear effects in the radiation force generated by amplitude-modulated focused beams

    Science.gov (United States)

    González, Nuria; Jiménez, Noé; Redondo, Javier; Roig, Bernardino; Picó, Rubén; Sánchez-Morcillo, Víctor; Konofagou, Elisa E.; Camarena, Francisco

    2012-10-01

    Harmonic Motion Imaging (HMI) uses an amplitude-modulated (AM) beam to induce an oscillatory radiation force before, during and after ablation. In this paper, the findings from a numerical analysis of the effects related with the nonlinear propagation of AM focused ultrasonic beams in water on the radiation force and the location of its maxima will be presented. The numerical modeling is performed using the KZK nonlinear parabolic equation. The radiation force is generated by a focused transducer with a gain of 18, a carrier frequency of 1 MHz and a modulation frequency of 25 kHz. The modulated excitation generates a spatially-invariant force proportional to the intensity. Regarding the nonlinear wave propagation, the force is no longer proportional to the intensity, reaching a factor of eight between the nonlinear and linear estimations. Also, a 9 mm shift in the on-axis force peak occurs when the initial pressure increased from 1 to 300 kPa. This spatial shift, due to the nonlinear effects, becomes dynamic in AM focused beams, as the different signal periods have different amplitudes. This study shows that both the value and the spatial position of the force peak are affected by the nonlinear propagation of the ultrasonic waves.

  13. Acoustic radiation force on a double-layer microsphere by a Gaussian focused beam

    International Nuclear Information System (INIS)

    Wu, Rongrong; Cheng, Kaixuan; Liu, Jiehui; Mao, Yiwei; Gong, Xiufen; Liu, Xiaozhou

    2014-01-01

    A new model for calculating the radiation force on double-layer microsphere is proposed based on the ray acoustics approach. The axial acoustic radiation force resulting from a focused Gaussian beam incident on spherical shells immersed in water is examined theoretically in relation to its thickness and the contents of its double-layer. The attenuation both in the water and inside the sphere is considered in this method, which cannot be ignored while the high frequency ultrasonic is used. Results of numerical calculations are presented for fat and low density polyethylene materials, with the hollow region filled with animal oil, water, or air. These results show how the acoustic impedance and the sound velocity of both layers, together with the thickness of the shell, affect the acoustic radiation force.

  14. The influence of the radiation pressure force on possible critical surfaces in binary systems

    International Nuclear Information System (INIS)

    Vanbeveren, D.

    1978-01-01

    Using a spherically symmetric approximation for the radiation pressure force to compute a possible critical surface for binary systems, previous authors found that the surface opens up at the far side of the companion. It is shown that this effect may be unreal, and could be a consequence of the simple approximation for the radiation pressure force, Due to the influence of the radiation force, mass will be lost over the whole surface of the star. In that way much mass could leave the system in massive binary systems. On the basis of evolutionary models, including mass loss by stellar wind, the results were applied on the X-ray binaries 3U 1700 - 37 and HD 77581. (Auth.)

  15. Magnitude and pattern of Arctic warming governed by the seasonality of radiative forcing.

    Science.gov (United States)

    Bintanja, R; Krikken, F

    2016-12-02

    Observed and projected climate warming is strongest in the Arctic regions, peaking in autumn/winter. Attempts to explain this feature have focused primarily on identifying the associated climate feedbacks, particularly the ice-albedo and lapse-rate feedbacks. Here we use a state-of-the-art global climate model in idealized seasonal forcing simulations to show that Arctic warming (especially in winter) and sea ice decline are particularly sensitive to radiative forcing in spring, during which the energy is effectively 'absorbed' by the ocean (through sea ice melt and ocean warming, amplified by the ice-albedo feedback) and consequently released to the lower atmosphere in autumn and winter, mainly along the sea ice periphery. In contrast, winter radiative forcing causes a more uniform response centered over the Arctic Ocean. This finding suggests that intermodel differences in simulated Arctic (winter) warming can to a considerable degree be attributed to model uncertainties in Arctic radiative fluxes, which peak in summer.

  16. Acoustic radiation force due to arbitrary incident fields on spherical particles in soft tissue

    Energy Technology Data Exchange (ETDEWEB)

    Treweek, Benjamin C., E-mail: btreweek@utexas.edu; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hamilton, Mark F. [Applied Research Laboratories, The University of Texas at Austin, P.O. Box 8029, Austin, TX 78713-8029 (United States)

    2015-10-28

    Acoustic radiation force is of interest in a wide variety of biomedical applications ranging from tissue characterization (e.g. elastography) to tissue treatment (e.g. high intensity focused ultrasound, kidney stone fragment removal). As tissue mechanical properties are reliable indicators of tissue health, the former is the focus of the present contribution. This is accomplished through an investigation of the acoustic radiation force on a spherical scatterer embedded in tissue. Properties of both the scatterer and the surrounding tissue are important in determining the magnitude and the direction of the force. As these properties vary, the force computation shows changes in magnitude and direction, which may enable more accurate noninvasive determination of tissue properties.

  17. Effect of chronic forced swimming stress on whole brain radiation induced cognitive dysfunction and related mechanism

    International Nuclear Information System (INIS)

    Zhang Yuan; Sun Rui; Zhu Yaqun; Zhang Liyuan; Ji Jianfeng; Li Kun; Tian Ye

    2014-01-01

    Objective: To explore whether chronic forced swimming stress could improve whole brain radiation induced cognitive dysfunction and possible mechanism. Methods: Thirty-nine one month old male Sprague-Dawley rats were randomized into sham control group(C), swimming group(C-S), radiation group(R), and radiation plus swimming group(R-S). Radiation groups were given a single dose of 20 Gy on whole-brain. Rats in the swimming groups were trained with swimming of 15 min/d, 5 d/w. Rat behavior was performed 3 months after radiation in an order of free activity in an open field and the Morris water maze test including the place navigation and spatial probe tests. Then, the protein expressions of BDNF, P-ERK, T-ERK, P-CREB and T-CREB in the rat hippocampus tissue were assayed by Western blot. Results: On the day 2, in the place navigation test of Morris water maze, the latency of swimming group was significantly shorter than that of sham group, the latency of sham group was significantly shorter than that of radiation group, and the latency of radiation swimming group was significantly shorter than that of radiation group(P 0.05). Western blot assay showed that the expressions of BDNF and its downstream signals including P-ERK and P-CREB were markedly reduced by radiation (P < 0.05), but this reduction was attenuated by the chronic forced swimming stress. Conclusion: The chronic forced swimming stress could improve whole brain radiation induced cognitive dysfunction by up-regulating the expressions of BDNF and its downstream signal molecules of P-ERK and P-CREB in hippocampus. (authors)

  18. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    OpenAIRE

    Y. Liu; W. Wu; M. P. Jensen; T. Toto

    2011-01-01

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fractio...

  19. Moderate Imaging Resolution Spectroradiometer (MODIS) Aerosol Optical Depth Retrieval for Aerosol Radiative Forcing

    Science.gov (United States)

    Asmat, A.; Jalal, K. A.; Ahmad, N.

    2018-02-01

    The present study uses the Aerosol Optical Depth (AOD) retrieved from Moderate Imaging Resolution Spectroradiometer (MODIS) data for the period from January 2011 until December 2015 over an urban area in Kuching, Sarawak. The results show the minimum AOD value retrieved from MODIS is -0.06 and the maximum value is 6.0. High aerosol loading with high AOD value observed during dry seasons and low AOD monitored during wet seasons. Multi plane regression technique used to retrieve AOD from MODIS (AODMODIS) and different statistics parameter is proposed by using relative absolute error for accuracy assessment in spatial and temporal averaging approach. The AODMODIS then compared with AOD derived from Aerosol Robotic Network (AERONET) Sunphotometer (AODAERONET) and the results shows high correlation coefficient (R2) for AODMODIS and AODAERONET with 0.93. AODMODIS used as an input parameters into Santa Barbara Discrete Ordinate Radiative Transfer (SBDART) model to estimate urban radiative forcing at Kuching. The observed hourly averaged for urban radiative forcing is -0.12 Wm-2 for top of atmosphere (TOA), -2.13 Wm-2 at the surface and 2.00 Wm-2 in the atmosphere. There is a moderate relationship observed between urban radiative forcing calculated using SBDART and AERONET which are 0.75 at the surface, 0.65 at TOA and 0.56 in atmosphere. Overall, variation in AOD tends to cause large bias in the estimated urban radiative forcing.

  20. Transverse components of the radiation force on nonspherical particles in the T-matrix formalism

    International Nuclear Information System (INIS)

    Saija, Rosalba; Antonia Iati, Maria; Giusto, Arianna; Denti, Paolo; Borghese, Ferdinando

    2005-01-01

    In the framework of the transition matrix approach, we calculate the force exerted by a plane wave (radiation force) on a dispersion of nonspherical particles modeled as aggregates of spheres. Beyond the customary radiation pressure we also consider the components of the radiation force in a plane orthogonal to the direction of incidence of the incoming wave (transverse components). Our calculations show that, although the latter are generally smaller than the radiation pressure, they are in no way negligible and may be important for some applications, e.g. when studying the dynamics of cosmic dust grains. We also calculate the ensemble average of the components of the radiation force over the orientation of the particles in two physically significant cases: the case of random distribution and the case in which the orientations are randomly distributed around an axis fixed in space (axial average). As expected, we find that, unlike the case of random orientation, the transverse components do not vanish for axial average

  1. Observational determination of surface radiative forcing by CO2 from 2000 to 2010.

    Science.gov (United States)

    Feldman, D R; Collins, W D; Gero, P J; Torn, M S; Mlawer, E J; Shippert, T R

    2015-03-19

    The climatic impact of CO2 and other greenhouse gases is usually quantified in terms of radiative forcing, calculated as the difference between estimates of the Earth's radiation field from pre-industrial and present-day concentrations of these gases. Radiative transfer models calculate that the increase in CO2 since 1750 corresponds to a global annual-mean radiative forcing at the tropopause of 1.82 ± 0.19 W m(-2) (ref. 2). However, despite widespread scientific discussion and modelling of the climate impacts of well-mixed greenhouse gases, there is little direct observational evidence of the radiative impact of increasing atmospheric CO2. Here we present observationally based evidence of clear-sky CO2 surface radiative forcing that is directly attributable to the increase, between 2000 and 2010, of 22 parts per million atmospheric CO2. The time series of this forcing at the two locations-the Southern Great Plains and the North Slope of Alaska-are derived from Atmospheric Emitted Radiance Interferometer spectra together with ancillary measurements and thoroughly corroborated radiative transfer calculations. The time series both show statistically significant trends of 0.2 W m(-2) per decade (with respective uncertainties of ±0.06 W m(-2) per decade and ±0.07 W m(-2) per decade) and have seasonal ranges of 0.1-0.2 W m(-2). This is approximately ten per cent of the trend in downwelling longwave radiation. These results confirm theoretical predictions of the atmospheric greenhouse effect due to anthropogenic emissions, and provide empirical evidence of how rising CO2 levels, mediated by temporal variations due to photosynthesis and respiration, are affecting the surface energy balance.

  2. Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula

    KAUST Repository

    Osipov, Sergey

    2015-08-27

    In this study we attempted to better quantify radiative effects of dust over the Arabian Peninsula and their dependence on input parameters. For this purpose we have developed a stand-alone column radiation transport model coupled with the Mie, T-matrix and geometric optics calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments were carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18–20 March 2012. Comprehensive ground-based observations and satellite retrievals were used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing were estimated both from the model and observations. Diurnal cycle of the shortwave instantaneous dust direct radiative forcing was studied for a range of aerosol and surface characteristics representative of the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing were evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions, along with anisotropic aerosol scattering, are mostly responsible for diurnal effects.

  3. Laser Wakefield Acceleration Driven by a CO2 Laser (STELLA-LW) - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Wayne D

    2008-06-27

    The original goals of the Staged Electron Laser Acceleration – Laser Wakefield (STELLA-LW) program were to investigate two new methods for laser wakefield acceleration (LWFA). In pseudo-resonant LWFA (PR-LWFA), a laser pulse experiences nonlinear pulse steepening while traveling through the plasma. This steepening allows the laser pulse to generate wakefields even though the laser pulse length is too long for resonant LWFA to occur. For the conditions of this program, PR-LWFA requires a minimum laser peak power of 3 TW and a low plasma density (10^16 cm^-3). Seeded self-modulated LWFA (seeded SM-LWFA) combines LWFA with plasma wakefield acceleration (PWFA). An ultrashort (~100 fs) electron beam bunch acts as a seed in a plasma to form a wakefield via PWFA. This wakefield is subsequently amplified by the laser pulse through a self-modulated LWFA process. At least 1 TW laser power and, for a ~100-fs bunch, a plasma density ~10^17 cm^-3 are required. STELLA-LW was located on Beamline #1 at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). The ATF TW CO2 laser served as the driving laser beam for both methods. For PR-LWFA, a single bunch was to probe the wakefield produced by the laser beam. For seeded SM-LWFA, the ATF linac would produce two bunches, where the first would be the seed and the second would be the witness. A chicane would compress the first bunch to enable it to generate wakefields via PWFA. The plasma source was a short-length, gas-filled capillary discharge with the laser beam tightly focused in the center of the capillary, i.e., no laser guiding was used, in order to obtain the needed laser intensity. During the course of the program, several major changes had to be made. First, the ATF could not complete the upgrade of the CO2 laser to the 3 TW peak power needed for the PR-LWFA experiment. Therefore, the PR-LWFA experiment had to be abandoned leaving only the seeded SM-LWFA experiment. Second, the ATF discovered that the

  4. Effects of anthropogenic emissions on tropospheric ozone and its radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Berntsen, T.; Isaksen, I.S.A.; Fuglestvedt, J.S.; Myhre, G.; Larsen, T. Alsvik; Stordal, F.; Freckleton, R.S.; Shine, K.P.

    1997-12-31

    As described in this report, changes in tropospheric ozone since pre-industrial times due to changes in emissions have been calculated by the University of Oslo global three-dimensional photochemical model. The radiative forcing caused by the increase in ozone has been calculated by means of two independent radiative transfer models: the University of Reading model (Reading), and the University of Oslo/Norwegian Institute for Air Research model (OsloRad). Significant increases in upper tropospheric ozone concentrations are found at northern mid-latitudes at about 10 km altitude. In the tropical regions the largest increase is found at about 15 km altitude. The increase is found to be caused mainly by enhanced in situ production due to transport of precursors from the boundary layer, with a smaller contribution from increased transport of ozone produced in the boundary layer. The lifetime of ozone in the troposphere decreased by about 35% as a result of enhanced concentrations of HO{sub 2}. The calculated increase in surface ozone in Europe is in good agreement with observations. The calculations of radiative forcing include the effect of clouds and allow for thermal adjustment in the stratosphere. The global and annual averaged radiative forcing at the tropopause from both models are in the lower part of the Intergovernmental Panel on Climate Change estimated range. The calculated radiative forcing is similar in magnitude to the negative radiative forcing by sulfate aerosols, but displaced southward in source regions at northern mid-latitudes. The increase in tropospheric ozone is calculated to have cooled the lower stratosphere by up to 0.9 K, with possibly half of this cooling occurring in the past 2 to 3 decades. 76 refs., 16 figs., 9 tabs.

  5. Accounting for radiative forcing from albedo change in future global land-use scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Andrew D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Calvin, Katherine V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Collins, William D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Edmonds, James A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-08-01

    We demonstrate the effectiveness of a new method for quantifying radiative forcing from land use and land cover change (LULCC) within an integrated assessment model, the Global Change Assessment Model (GCAM). The method relies on geographically differentiated estimates of radiative forcing from albedo change associated with major land cover transitions derived from the Community Earth System Model. We find that conversion of 1 km² of woody vegetation (forest and shrublands) to non-woody vegetation (crops and grassland) yields between 0 and –0.71 nW/m² of globally averaged radiative forcing determined by the vegetation characteristics, snow dynamics, and atmospheric radiation environment characteristic within each of 151 regions we consider globally. Across a set of scenarios designed to span a range of potential future LULCC, we find LULCC forcing ranging from –0.06 to –0.29 W/m² by 2070 depending on assumptions regarding future crop yield growth and whether climate policy favors afforestation or bioenergy crops. Inclusion of this previously uncounted forcing in the policy targets driving future climate mitigation efforts leads to changes in fossil fuel emissions on the order of 1.5 PgC/yr by 2070 for a climate forcing limit of 4.5 Wm–2, corresponding to a 12–67 % change in fossil fuel emissions depending on the scenario. Scenarios with significant afforestation must compensate for albedo-induced warming through additional emissions reductions, and scenarios with significant deforestation need not mitigate as aggressively due to albedo-induced cooling. In all scenarios considered, inclusion of albedo forcing in policy targets increases forest and shrub cover globally.

  6. Radiofrequency radiation: safe working practices in the Royal Australian Air Force

    International Nuclear Information System (INIS)

    Joyner, K.H.; Stone, K.R.

    1988-01-01

    The Royal Australian Air Force (RAAF) has long recognised the value of its work force and the need to preserve their health and wellbeing to achieve operational objectives. The Directorate of Air Force Safety (DAFS) is required by the Chief of the Air Staff to take all measures possible to prevent accidents and incidents in the RAAF, under the provisions of the Defence Instruction, 'Air Force Safety and Occupational Health Policy'. Consequently, the RAAF has exercised a pragmatic approach to radiofrequency radiation (RFR) and has always adopted and implemented strict exposure standards. DAFS receives technical advice on RFR from the Directorate of Telecommunications Engineering (DTELENG) and on occupational health from the Directorate General of Air Force Health Services (DGAFHS)

  7. Note: Measurement system for the radiative forcing of greenhouse gases in a laboratory scale

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Yoshiyuki [Department of Intelligent Mechanical Engineering, Fukuoka Institute of Technology, 3-30-1 Wajirohigashi, Higashiku, Fukuoka 811-0295 (Japan)

    2016-01-15

    The radiative forcing of the greenhouse gases has been studied being based on computational simulations or the observation of the real atmosphere meteorologically. In order to know the greenhouse effect more deeply and to study it from various viewpoints, the study on it in a laboratory scale is important. We have developed a direct measurement system for the infrared back radiation from the carbon dioxide (CO{sub 2}) gas. The system configuration is similar with that of the practical earth-atmosphere-space system. Using this system, the back radiation from the CO{sub 2} gas was directly measured in a laboratory scale, which roughly coincides with meteorologically predicted value.

  8. Note: Measurement system for the radiative forcing of greenhouse gases in a laboratory scale.

    Science.gov (United States)

    Kawamura, Yoshiyuki

    2016-01-01

    The radiative forcing of the greenhouse gases has been studied being based on computational simulations or the observation of the real atmosphere meteorologically. In order to know the greenhouse effect more deeply and to study it from various viewpoints, the study on it in a laboratory scale is important. We have developed a direct measurement system for the infrared back radiation from the carbon dioxide (CO2) gas. The system configuration is similar with that of the practical earth-atmosphere-space system. Using this system, the back radiation from the CO2 gas was directly measured in a laboratory scale, which roughly coincides with meteorologically predicted value.

  9. A general method for computing the total solar radiation force on complex spacecraft structures

    Science.gov (United States)

    Chan, F. K.

    1981-01-01

    The method circumvents many of the existing difficulties in computational logic presently encountered in the direct analytical or numerical evaluation of the appropriate surface integral. It may be applied to complex spacecraft structures for computing the total force arising from either specular or diffuse reflection or even from non-Lambertian reflection and re-radiation.

  10. Anthropogenic radiative forcing of southern African and Southern Hemisphere climate variability and change

    CSIR Research Space (South Africa)

    Engelbrecht, FA

    2014-10-01

    Full Text Available of stratospheric ozone, greenhouse gasses, aerosols and sulphur dioxide, can improve the model's skill to simulate inter-annual variability over southern Africa. The paper secondly explores the role of different radiative forcings of future climate change over...

  11. Impacts of Human Alteration of the Nitrogen Cycle in the U.S. on Radiative Forcing

    Science.gov (United States)

    Nitrogen cycling processes affect radiative forcing directly through emissions of nitrous oxide (N2O) and indirectly because emissions of nitrogen oxide (NO x ) and ammonia (NH3) affect atmospheric concentrations of methane (CH4), carbon dioxide (CO2), water vapor (H2O), ozone (O...

  12. Sonic excitation by means of ultrasound; an experimental illustration of acoustic radiation forces

    NARCIS (Netherlands)

    Roozen, N.B.; Nuij, P.W.J.M.

    2011-01-01

    Ultrasonic acoustic waves are known to induce a vibration of particles around an equilibrium position. However, for large acoustic amplitudes, due to non-linear acoustic effects, a rectified, net acoustic radiation force can occur. Experimental work is performed in which the non-linear behavior is

  13. Numerical study of acoustic streaming and radiation forces on micro particles

    DEFF Research Database (Denmark)

    Jensen, Mads Jakob Herring; Muller, Peter Barkholt; Barnkob, Rune

    2012-01-01

    , and 2) Stokes drag from the induced acoustic streaming flow. Both effects are second order and require the solution of the full linearized Navier-Stokes equation in order to be captured correctly. The model shows the transition from streaming drag to radiation force dominated regimes. The transition...

  14. LW6, a hypoxia-inducible factor 1 inhibitor, selectively induces apoptosis in hypoxic cells through depolarization of mitochondria in A549 human lung cancer cells.

    Science.gov (United States)

    Sato, Mariko; Hirose, Katsumi; Kashiwakura, Ikuo; Aoki, Masahiko; Kawaguchi, Hideo; Hatayama, Yoshiomi; Akimoto, Hiroyoshi; Narita, Yuichiro; Takai, Yoshihiro

    2015-09-01

    Hypoxia‑inducible factor 1 (HIF‑1) activates the transcription of genes that act upon the adaptation of cancer cells to hypoxia. LW6, an HIF‑1 inhibitor, was hypothesized to improve resistance to cancer therapy in hypoxic tumors by inhibiting the accumulation of HIF‑1α. A clear anti‑tumor effect under low oxygen conditions would indicate that LW6 may be an improved treatment strategy for cancer in hypoxia. In the present study, the HIF‑1 inhibition potential of LW6 on the growth and apoptosis of A549 lung cancer cells in association with oxygen availability was evaluated. LW6 was observed to inhibit the expression of HIF‑1α induced by hypoxia in A549 cells at 20 mM, independently of the von Hippel‑Lindau protein. In addition, at this concentration, LW6 induced hypoxia‑selective apoptosis together with a reduction in the mitochondrial membrane potential. The intracellular reactive oxygen species levels increased in LW6‑treated hypoxic A549 cells and LW6 induced a hypoxia‑selective increase of mitochondrial O2•‑. In conclusion, LW6 inhibited the growth of hypoxic A549 cells by affecting the mitochondria. The inhibition of the mitochondrial respiratory chain is suggested as a potentially effective strategy to target apoptosis in cancer cells.

  15. Reduced anthropogenic aerosol radiative forcing caused by biogenic new particle formation

    Science.gov (United States)

    Gordon, Hamish; Sengupta, Kamalika; Rap, Alexandru; Duplissy, Jonathan; Frege, Carla; Williamson, Christina; Heinritzi, Martin; Simon, Mario; Yan, Chao; Almeida, João; Tröstl, Jasmin; Nieminen, Tuomo; Ortega, Ismael K.; Wagner, Robert; Dunne, Eimear M.; Adamov, Alexey; Amorim, Antonio; Bernhammer, Anne-Kathrin; Bianchi, Federico; Breitenlechner, Martin; Brilke, Sophia; Chen, Xuemeng; Craven, Jill S.; Dias, Antonio; Ehrhart, Sebastian; Fischer, Lukas; Flagan, Richard C.; Franchin, Alessandro; Fuchs, Claudia; Guida, Roberto; Hakala, Jani; Hoyle, Christopher R.; Jokinen, Tuija; Junninen, Heikki; Kangasluoma, Juha; Kim, Jaeseok; Kirkby, Jasper; Krapf, Manuel; Kürten, Andreas; Laaksonen, Ari; Lehtipalo, Katrianne; Makhmutov, Vladimir; Mathot, Serge; Molteni, Ugo; Monks, Sarah A.; Onnela, Antti; Peräkylä, Otso; Piel, Felix; Petäjä, Tuukka; Praplan, Arnaud P.; Pringle, Kirsty J.; Richards, Nigel A. D.; Rissanen, Matti P.; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Scott, Catherine E.; Seinfeld, John H.; Sharma, Sangeeta; Sipilä, Mikko; Steiner, Gerhard; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Virtanen, Annele; Vogel, Alexander Lucas; Wagner, Andrea C.; Wagner, Paul E.; Weingartner, Ernest; Wimmer, Daniela; Winkler, Paul M.; Ye, Penglin; Zhang, Xuan; Hansel, Armin; Dommen, Josef; Donahue, Neil M.; Worsnop, Douglas R.; Baltensperger, Urs; Kulmala, Markku; Curtius, Joachim; Carslaw, Kenneth S.

    2016-10-01

    The magnitude of aerosol radiative forcing caused by anthropogenic emissions depends on the baseline state of the atmosphere under pristine preindustrial conditions. Measurements show that particle formation in atmospheric conditions can occur solely from biogenic vapors. Here, we evaluate the potential effect of this source of particles on preindustrial cloud condensation nuclei (CCN) concentrations and aerosol-cloud radiative forcing over the industrial period. Model simulations show that the pure biogenic particle formation mechanism has a much larger relative effect on CCN concentrations in the preindustrial atmosphere than in the present atmosphere because of the lower aerosol concentrations. Consequently, preindustrial cloud albedo is increased more than under present day conditions, and therefore the cooling forcing of anthropogenic aerosols is reduced. The mechanism increases CCN concentrations by 20-100% over a large fraction of the preindustrial lower atmosphere, and the magnitude of annual global mean radiative forcing caused by changes of cloud albedo since 1750 is reduced by 0.22 W m-2 (27%) to -0.60 W m-2. Model uncertainties, relatively slow formation rates, and limited available ambient measurements make it difficult to establish the significance of a mechanism that has its dominant effect under preindustrial conditions. Our simulations predict more particle formation in the Amazon than is observed. However, the first observation of pure organic nucleation has now been reported for the free troposphere. Given the potentially significant effect on anthropogenic forcing, effort should be made to better understand such naturally driven aerosol processes.

  16. Self-consistent Optomechanical Dynamics and Radiation Forces in Thermal Light Fields

    International Nuclear Information System (INIS)

    Sonnleitner, M.

    2014-01-01

    We discuss two different aspects of the mechanical interaction between neutral matter and electromagnetic radiation.The first part addresses the complex dynamics of an elastic dielectric deformed by optical forces. To do so we use a one-dimensional model describing the medium by an array of beam splitters such that the interaction with the incident waves can be described with a transfer-matrix approach. Since the force on each individual beam splitter is known we thus obtain the correct volumetric force density inside the medium. Sending a light field through an initially homogeneous dielectric then results in density modulations which in turn alter the optical properties of this medium.The second part is concerned with mechanical light-effects on atoms in thermal radiation fields. At hand of a generic setup of an atom interacting with a hot sphere emitting blackbody radiation we show that the emerging gradient force may surpass gravity by several orders of magnitude. The strength of the repulsive scattering force strongly depends on the spectrum of the involved atoms and can be neglected in some setups. A special emphasis lies on possible implications on astrophysical scenarios where the interactions between heated dust and atoms, molecules or nanoparticles are of crucial interest. (author) [de

  17. Reduced anthropogenic aerosol radiative forcing caused by biogenic new particle formation.

    Science.gov (United States)

    Gordon, Hamish; Sengupta, Kamalika; Rap, Alexandru; Duplissy, Jonathan; Frege, Carla; Williamson, Christina; Heinritzi, Martin; Simon, Mario; Yan, Chao; Almeida, João; Tröstl, Jasmin; Nieminen, Tuomo; Ortega, Ismael K; Wagner, Robert; Dunne, Eimear M; Adamov, Alexey; Amorim, Antonio; Bernhammer, Anne-Kathrin; Bianchi, Federico; Breitenlechner, Martin; Brilke, Sophia; Chen, Xuemeng; Craven, Jill S; Dias, Antonio; Ehrhart, Sebastian; Fischer, Lukas; Flagan, Richard C; Franchin, Alessandro; Fuchs, Claudia; Guida, Roberto; Hakala, Jani; Hoyle, Christopher R; Jokinen, Tuija; Junninen, Heikki; Kangasluoma, Juha; Kim, Jaeseok; Kirkby, Jasper; Krapf, Manuel; Kürten, Andreas; Laaksonen, Ari; Lehtipalo, Katrianne; Makhmutov, Vladimir; Mathot, Serge; Molteni, Ugo; Monks, Sarah A; Onnela, Antti; Peräkylä, Otso; Piel, Felix; Petäjä, Tuukka; Praplan, Arnaud P; Pringle, Kirsty J; Richards, Nigel A D; Rissanen, Matti P; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Scott, Catherine E; Seinfeld, John H; Sharma, Sangeeta; Sipilä, Mikko; Steiner, Gerhard; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Virtanen, Annele; Vogel, Alexander Lucas; Wagner, Andrea C; Wagner, Paul E; Weingartner, Ernest; Wimmer, Daniela; Winkler, Paul M; Ye, Penglin; Zhang, Xuan; Hansel, Armin; Dommen, Josef; Donahue, Neil M; Worsnop, Douglas R; Baltensperger, Urs; Kulmala, Markku; Curtius, Joachim; Carslaw, Kenneth S

    2016-10-25

    The magnitude of aerosol radiative forcing caused by anthropogenic emissions depends on the baseline state of the atmosphere under pristine preindustrial conditions. Measurements show that particle formation in atmospheric conditions can occur solely from biogenic vapors. Here, we evaluate the potential effect of this source of particles on preindustrial cloud condensation nuclei (CCN) concentrations and aerosol-cloud radiative forcing over the industrial period. Model simulations show that the pure biogenic particle formation mechanism has a much larger relative effect on CCN concentrations in the preindustrial atmosphere than in the present atmosphere because of the lower aerosol concentrations. Consequently, preindustrial cloud albedo is increased more than under present day conditions, and therefore the cooling forcing of anthropogenic aerosols is reduced. The mechanism increases CCN concentrations by 20-100% over a large fraction of the preindustrial lower atmosphere, and the magnitude of annual global mean radiative forcing caused by changes of cloud albedo since 1750 is reduced by [Formula: see text] (27%) to [Formula: see text] Model uncertainties, relatively slow formation rates, and limited available ambient measurements make it difficult to establish the significance of a mechanism that has its dominant effect under preindustrial conditions. Our simulations predict more particle formation in the Amazon than is observed. However, the first observation of pure organic nucleation has now been reported for the free troposphere. Given the potentially significant effect on anthropogenic forcing, effort should be made to better understand such naturally driven aerosol processes.

  18. Reduction of vibration forces transmitted from a radiator cooling fan to a vehicle body

    Science.gov (United States)

    Lim, Jonghyuk; Sim, Woojeong; Yun, Seen; Lee, Dongkon; Chung, Jintai

    2018-04-01

    This article presents methods for reducing transmitted vibration forces caused by mass unbalance of the radiator cooling fan during vehicle idling. To identify the effects of mass unbalance upon the vibration characteristics, vibration signals of the fan blades were experimentally measured both with and without an added mass. For analyzing the vibration forces transmitted to the vehicle body, a dynamic simulation model was established that reflected the vibration characteristics of the actual system. This process included a method described herein for calculating the equivalent stiffness and the equivalent damping of the shroud stators and rubber mountings. The dynamic simulation model was verified by comparing its results with experimental results of the radiator cooling fan. The dynamic simulation model was used to analyze the transmitted vibration forces at the rubber mountings. Also, a measure was established to evaluate the effects of varying the design parameters upon the transmitted vibration forces. We present design guidelines based on these analyses to reduce the transmitted vibration forces of the radiator cooling fan.

  19. Direct and semi-direct radiative forcing of smoke aerosols over clouds

    Directory of Open Access Journals (Sweden)

    E. M. Wilcox

    2012-01-01

    Full Text Available Observations from Earth observing satellites indicate that dark carbonaceous aerosols that absorb solar radiation are widespread in the tropics and subtropics. When these aerosols mix with clouds, there is generally a reduction of cloudiness owing to absorption of solar energy in the aerosol layer. Over the subtropical South Atlantic Ocean, where smoke from savannah burning in southern Africa resides above a persistent deck of marine stratocumulus clouds, radiative heating of the smoke layer leads to a thickening of the cloud layer. Here, satellite observations of the albedo of overcast scenes of 25 km2 size or larger are combined with additional satellite observations of clouds and aerosols to estimate the top-of-atmosphere direct radiative forcing attributable to presence of dark aerosol above bright cloud, and the negative semi-direct forcing attributable to the thickening of the cloud layer. The average positive direct radiative forcing by smoke over an overcast scene is 9.2±6.6 W m−2 for cases with an unambiguous signal of absorbing aerosol over cloud in passive ultraviolet remote sensing observations. However, cloud liquid water path is enhanced by 16.3±7.7 g m−2 across the range of values for sea surface temperature for cases of smoke over cloud. The negative radiative forcing associated with this semi-direct effect of smoke over clouds is estimated to be −5.9±3.5 W m−2. Therefore, the cooling associated with the semi-direct cloud thickening effect compensates for greater than 60 % of the direct radiative effect. Accounting for the frequency of occurrence of significant absorbing aerosol above overcast scenes leads to an estimate of the average direct forcing of 1.0±0.7 W m−2 contributed by these scenes averaged over the subtropical southeast Atlantic Ocean during austral winter. The regional average of the negative semi-direct forcing is −0.7±0.4 W m−2

  20. Climate Response to Negative Greenhouse Gas Radiative Forcing in Polar Winter

    Science.gov (United States)

    Flanner, M. G.; Huang, X.; Chen, X.; Krinner, G.

    2018-02-01

    Greenhouse gas (GHG) additions to Earth's atmosphere initially reduce global outgoing longwave radiation, thereby warming the planet. In select environments with temperature inversions, however, increased GHG concentrations can actually increase local outgoing longwave radiation. Negative top of atmosphere and effective radiative forcing (ERF) from this situation give the impression that local surface temperatures could cool in response to GHG increases. Here we consider an extreme scenario in which GHG concentrations are increased only within the warmest layers of winter near-surface inversions of the Arctic and Antarctic. We find, using a fully coupled Earth system model, that the underlying surface warms despite the GHG addition exerting negative ERF and cooling the troposphere in the vicinity of the GHG increase. This unique radiative forcing and thermal response is facilitated by the high stability of the polar winter atmosphere, which inhibit thermal mixing and amplify the impact of surface radiative forcing on surface temperature. These findings also suggest that strategies to exploit negative ERF via injections of short-lived GHGs into inversion layers would likely be unsuccessful in cooling the planetary surface.

  1. Direct radiative forcing due to aerosols in Asia during March 2002.

    Science.gov (United States)

    Park, Soon-Ung; Jeong, Jaein I

    2008-12-15

    The Asian dust aerosol model (ADAM) and the aerosol dynamic model including the gas-aerosol interaction processes together with the Column Radiation Model (CRM) of Community Climate Model 3 and the output of the fifth generation of meso-scale model (MM5) in a grid 60 x 60 km2 in the Asian domain (70-150E, Equator-50N) have been employed to estimate direct radiative forcing of the Asian dust and the anthropogenic aerosols including the BC, OC, secondary inorganic aerosol (SIA), mixed type aerosol (dust+BC+OC+SIA) and sea salt aerosols at the surface, the top of atmosphere (TOA) and in the atmosphere for the period of 1-31 March 2002 during which a severe Asian dust event has been occurred in the model domain. The results indicate that the ADAM model and the aerosol dynamic model simulate quite well the spatial and temporal distributions of the mass concentration of aerosols with the R2 value of more than 0.7. The estimated mean total column aerosol mass in the analysis domain for the whole period is found to be about 78 mg m(-2), of which 66% and 34% are, respectively, contributed by the Asian dust aerosol and all the other anthropogenic aerosols. However, the direct radiative forcing contributed by the Asian dust aerosol is about 22% of the mean radiative forcing at the surface (-6.8 W m(-2)), about 31% at the top of atmosphere (-2.9 W m(-2)) and about 13% in the atmosphere (3.8 W m(-2)), suggesting relatively inefficient contribution of the Asian dust aerosol on the direct radiative forcing compared to the anthropogenic aerosols. The aerosol direct radiative forcing at the surface is mainly contributed by the mixed type aerosol (30%) and the SIA aerosol (25%) while at the top of atmosphere it is mainly contributed by the SIA aerosol (43%) and the Asian dust aerosol (31%) with positively (warming) contributed by BC and mixed type aerosols. The atmosphere is warmed mainly by the mixed type aerosol (55%) and the BC aerosol (26%). However, the largest radiative

  2. Direct radiative forcing due to aerosols in Asia during March 2002

    International Nuclear Information System (INIS)

    Park, Soon-Ung; Jeong, Jaein I.

    2008-01-01

    The Asian dust aerosol model (ADAM) and the aerosol dynamic model including the gas-aerosol interaction processes together with the Column Radiation Model (CRM) of Community Climate Model 3 and the output of the fifth generation of meso-scale model (MM5) in a grid 60 x 60 km 2 in the Asian domain (70-150E, Equator-50N) have been employed to estimate direct radiative forcing of the Asian dust and the anthropogenic aerosols including the BC, OC, secondary inorganic aerosol (SIA), mixed type aerosol (dust + BC + OC + SIA) and sea salt aerosols at the surface, the top of atmosphere (TOA) and in the atmosphere for the period of 1-31 March 2002 during which a severe Asian dust event has been occurred in the model domain. The results indicate that the ADAM model and the aerosol dynamic model simulate quite well the spatial and temporal distributions of the mass concentration of aerosols with the R 2 value of more than 0.7. The estimated mean total column aerosol mass in the analysis domain for the whole period is found to be about 78 mg m -2 , of which 66% and 34% are, respectively, contributed by the Asian dust aerosol and all the other anthropogenic aerosols. However, the direct radiative forcing contributed by the Asian dust aerosol is about 22% of the mean radiative forcing at the surface (- 6.8 W m -2 ), about 31% at the top of atmosphere (- 2.9 W m -2 ) and about 13% in the atmosphere (3.8 W m -2 ), suggesting relatively inefficient contribution of the Asian dust aerosol on the direct radiative forcing compared to the anthropogenic aerosols. The aerosol direct radiative forcing at the surface is mainly contributed by the mixed type aerosol (30%) and the SIA aerosol (25%) while at the top of atmosphere it is mainly contributed by the SIA aerosol (43%) and the Asian dust aerosol (31%) with positively (warming) contributed by BC and mixed type aerosols. The atmosphere is warmed mainly by the mixed type aerosol (55%) and the BC aerosol (26%). However, the largest

  3. Structural analysis of γ radiation-induced chromosomal aberrations observed by atomic force microscopy

    International Nuclear Information System (INIS)

    Qu Shuang; Chen Ying; Ge Shili; Liu Xiulin; Zhou Pingkun; Zhang Sa; Zhang Detian

    2003-01-01

    Objective: To find a new method for the measurement of radiation-induced damage, the structures of normal chromosomes and 60 Co γ-ray-induced chromosomal aberration were analyzed by atomic force microscopy. Methods: Normal and irradiated chromosomes of human peripheral blood lymphocytes were prepared, then three-dimensional structure and height of chromosomes were analyzed by atomic force microscopy. Results: Three-dimensional structures of normal chromosomes and dicentric aberration in irradiated chromosomes were observed clearly. The data of chromosome height were helpful to recognizing the dicentric aberrations. Conclusion: Atomic force microscopy providing three-dimension image and linear measurement is a new and valuable tool for structural analysis of radiation-induced chromosomal aberrations

  4. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    International Nuclear Information System (INIS)

    Mitri, F. G.

    2015-01-01

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries

  5. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Science.gov (United States)

    Mitri, F. G.

    2015-12-01

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  6. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Energy Technology Data Exchange (ETDEWEB)

    Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology–ETC, Santa Fe, New Mexico 87508 (United States)

    2015-12-07

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  7. Acoustic backscattering and radiation force on a rigid elliptical cylinder in plane progressive waves.

    Science.gov (United States)

    Mitri, F G

    2016-03-01

    This work proposes a formal analytical theory using the partial-wave series expansion (PWSE) method in cylindrical coordinates, to calculate the acoustic backscattering form function as well as the radiation force-per-length on an infinitely long elliptical (non-circular) cylinder in plane progressive waves. The major (or minor) semi-axis of the ellipse coincides with the direction of the incident waves. The scattering coefficients for the rigid elliptical cylinder are determined by imposing the Neumann boundary condition for an immovable surface and solving a resulting system of linear equations by matrix inversion. The present method, which utilizes standard cylindrical (Bessel and Hankel) wave functions, presents an advantage over the solution for the scattering that is ordinarily expressed in a basis of elliptical Mathieu functions (which are generally non-orthogonal). Furthermore, an integral equation showing the direct connection of the radiation force function with the square of the scattering form function in the far-field from the scatterer (applicable for plane waves only), is noted and discussed. An important application of this integral equation is the adequate evaluation of the radiation force function from a bistatic measurement (i.e., in the polar plane) of the far-field scattering from any 2D object of arbitrary shape. Numerical predictions are evaluated for the acoustic backscattering form function and the radiation force function, which is the radiation force per unit length, per characteristic energy density, and per unit cross-sectional surface of the ellipse, with particular emphasis on the aspect ratio a/b, where a and b are the semi-axes, as well as the dimensionless size parameter kb, without the restriction to a particular range of frequencies. The results are particularly relevant in acoustic levitation, acousto-fluidics and particle dynamics applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets

    International Nuclear Information System (INIS)

    Menon, Surabi; Akbari, Hashem; Sednev, Igor; Levinson, Ronnen; Mahanama, Sarith

    2010-01-01

    The two main forcings that can counteract to some extent the positive forcings from greenhouse gases from pre-industrial times to present day are the aerosol and related aerosol-cloud forcings, and the radiative response to changes in surface albedo. Here, we quantify the change in radiative forcing and land surface temperature that may be obtained by increasing the albedos of roofs and pavements in urban areas in temperate and tropical regions of the globe by 0.1. Using the catchment land surface model (the land model coupled to the GEOS-5 Atmospheric General Circulation Model), we quantify the change in the total outgoing (outgoing shortwave+longwave) radiation and land surface temperature to a 0.1 increase in urban albedos for all global land areas. The global average increase in the total outgoing radiation was 0.5 W m -2 , and temperature decreased by ∼0.008 K for an average 0.003 increase in surface albedo. These averages represent all global land areas where data were available from the land surface model used and are for the boreal summer (June-July-August). For the continental US the total outgoing radiation increased by 2.3 W m -2 , and land surface temperature decreased by ∼0.03 K for an average 0.01 increase in surface albedo. Based on these forcings, the expected emitted CO 2 offset for a plausible 0.25 and 0.15 increase in albedos of roofs and pavements, respectively, for all global urban areas, was found to be ∼57 Gt CO 2 . A more meaningful evaluation of the impacts of urban albedo increases on global climate and the expected CO 2 offsets would require simulations which better characterize urban surfaces and represent the full annual cycle.

  9. Expert judgments about transient climate response to alternative future trajectories of radiative forcing.

    Science.gov (United States)

    Zickfeld, Kirsten; Morgan, M Granger; Frame, David J; Keith, David W

    2010-07-13

    There is uncertainty about the response of the climate system to future trajectories of radiative forcing. To quantify this uncertainty we conducted face-to-face interviews with 14 leading climate scientists, using formal methods of expert elicitation. We structured the interviews around three scenarios of radiative forcing stabilizing at different levels. All experts ranked "cloud radiative feedbacks" as contributing most to their uncertainty about future global mean temperature change, irrespective of the specified level of radiative forcing. The experts disagreed about the relative contribution of other physical processes to their uncertainty about future temperature change. For a forcing trajectory that stabilized at 7 Wm(-2) in 2200, 13 of the 14 experts judged the probability that the climate system would undergo, or be irrevocably committed to, a "basic state change" as > or =0.5. The width and median values of the probability distributions elicited from the different experts for future global mean temperature change under the specified forcing trajectories vary considerably. Even for a moderate increase in forcing by the year 2050, the medians of the elicited distributions of temperature change relative to 2000 range from 0.8-1.8 degrees C, and some of the interquartile ranges do not overlap. Ten of the 14 experts estimated that the probability that equilibrium climate sensitivity exceeds 4.5 degrees C is > 0.17, our interpretation of the upper limit of the "likely" range given by the Intergovernmental Panel on Climate Change. Finally, most experts anticipated that over the next 20 years research will be able to achieve only modest reductions in their degree of uncertainty.

  10. An automated approach to Litchfield and Wilcoxon's evaluation of dose–effect experiments using the R package LW1949

    Science.gov (United States)

    Adams, Jean V.; Slaght, Karen; Boogaard, Michael A.

    2016-01-01

    The authors developed a package, LW1949, for use with the statistical software R to automatically carry out the manual steps of Litchfield and Wilcoxon's method of evaluating dose–effect experiments. The LW1949 package consistently finds the best fitting dose–effect relation by minimizing the chi-squared statistic of the observed and expected number of affected individuals and substantially speeds up the line-fitting process and other calculations that Litchfield and Wilcoxon originally carried out by hand. Environ Toxicol Chem 2016;9999:1–4. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

  11. Revised model for the radiation force exerted by standing surface acoustic waves on a rigid cylinder

    Science.gov (United States)

    Liang, Shen; Chaohui, Wang

    2018-03-01

    In this paper, a model for the radiation force exerted by standing surface acoustic waves (SSAWs) on a rigid cylinder in inviscid fluids is extended to account for the dependence on the Rayleigh angle. The conventional model for the radiation force used in the SSAW-based applications is developed in plane standing waves, which fails to predict the movement of the cylinder in the SSAW. Our revised model reveals that, in the direction normal to the piezoelectric substrate on which the SSAW is generated, acoustic radiation force can be large enough to drive the cylinder even in the long-wavelength limit. Furthermore, the force in this direction can not only push the cylinder away, but also pull it back toward the substrate. In the direction parallel to the substrate, the equilibrium positions for particles can be actively tuned by changing Rayleigh angle. As an example considered in the paper, with the reduction of Rayleigh angle the equilibrium positions for steel cylinders in water change from pressure nodes to pressure antinodes. The model can thus be used in the design of SSAWs for particle manipulations.

  12. Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    M. Kopacz

    2011-03-01

    Full Text Available The remote and high elevation regions of central Asia are influenced by black carbon (BC emissions from a variety of locations. BC deposition contributes to melting of glaciers and questions exist, of both scientific and policy interest, as to the origin of the BC reaching the glaciers. We use the adjoint of the GEOS-Chem model to identify the location from which BC arriving at a variety of locations in the Himalayas and Tibetan Plateau originates. We then calculate its direct and snow-albedo radiative forcing. We analyze the seasonal variation in the origin of BC using an adjoint sensitivity analysis, which provides a detailed map of the location of emissions that directly contribute to black carbon concentrations at receptor locations. We find that emissions from northern India and central China contribute the majority of BC to the Himalayas, although the precise location varies with season. The Tibetan Plateau receives most BC from western and central China, as well as from India, Nepal, the Middle East, Pakistan and other countries. The magnitude of contribution from each region varies with season and receptor location. We find that sources as varied as African biomass burning and Middle Eastern fossil fuel combustion can significantly contribute to the BC reaching the Himalayas and Tibetan Plateau. We compute radiative forcing in the snow-covered regions and find the forcing due to the BC induced snow-albedo effect to vary from 5–15 W m−2 within the region, an order of magnitude larger than radiative forcing due to the direct effect, and with significant seasonal variation in the northern Tibetan Plateau. Radiative forcing from reduced snow albedo likely accelerates glacier melting. Our analysis may help inform mitigation efforts to slow the rate of glacial melt by identifying regions that make the largest contributions to BC deposition in the Himalayas and Tibetan Plateau.

  13. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  14. A simulation technique for 3D MR-guided acoustic radiation force imaging

    International Nuclear Information System (INIS)

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-01-01

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison

  15. Pushing, pulling and electromagnetic radiation force cloaking by a pair of conducting cylindrical particles

    Science.gov (United States)

    Mitri, F. G.

    2018-02-01

    The present analysis shows that two conducting cylindrical particles illuminated by an axially-polarized electric field of plane progressive waves at arbitrary incidence will attract, repel or become totally cloaked (i.e., invisible to the transfer of linear momentum carried by the incident waves), depending on their sizes, the interparticle distance as well as the angle of incidence of the incident field. Based on the rigorous multipole expansion method and the translational addition theorem of cylindrical wave functions, the electromagnetic (EM) radiation forces arising from multiple scattering effects between a pair of perfectly conducting cylindrical particles of circular cross-sections are derived and computed. An effective incident field on a particular particle is determined first, and used subsequently with its corresponding scattered field to derive the closed-form analytical expressions for the radiation force vector components. The mathematical expressions for the EM radiation force components (i.e. longitudinal and transverse) are exact, and have been formulated in partial-wave series expansions in cylindrical coordinates involving the angle of incidence, the interparticle distance and the expansion coefficients. Numerical examples illustrate the analysis for two perfectly conducting circular cylinders in a homogeneous nonmagnetic medium of wave propagation. The computations for the dimensionless radiation force functions are performed with particular emphasis on varying the angle of incidence, the interparticle distance, and the sizes of the particles. Depending on the interparticle distance and angle of incidence, the cylinders yield total neutrality (or invisibility); they experience no force and become unresponsive to the transfer of the EM linear momentum due to multiple scattering cancellation effects. Moreover, pushing or pulling EM forces between the two cylinders arise depending on the interparticle distance, the angle of incidence and their

  16. Tailored long range forces on polarizable particles by collective scattering of broadband radiation

    International Nuclear Information System (INIS)

    Holzmann, D; Ritsch, H

    2016-01-01

    Collective coherent light scattering by polarizable particles creates surprisingly strong, long range inter-particle forces originating from interference of the light scattered by different particles. While for monochromatic laser beams this interaction decays with the inverse distance, we show here that in general the effective interaction range and geometry can be controlled by the illumination bandwidth and geometry. As generic example we study the modifications inter-particle forces within a 1D chain of atoms trapped in the field of a confined optical nanofiber mode. For two particles we find short range attraction as well as optical binding at multiple distances. The range of stable distances shrinks with increasing light bandwidth and for a very large bandwidth field as e.g. blackbody radiation. We find a strongly attractive potential up to a critical distance beyond which the force gets repulsive. Including multiple scattering can even lead to the appearance of a stable configuration at a large distance. Such broadband scattering forces should be observable contributions in ultra-cold atom interferometers or atomic clocks setups. They could be studied in detail in 1D geometries with ultra-cold atoms trapped along or within an optical nanofiber. Broadband radiation force interactions might also contribute in astrophysical scenarios as illuminated cold dust clouds. (paper)

  17. Response of heterogeneous vegetation to aerosol radiative forcing over a northeast Indian station.

    Science.gov (United States)

    Latha, R; Vinayak, B; Murthy, B S

    2018-01-15

    Importance of atmospheric aerosols through direct and indirect effects on hydrological cycle is highlighted through multiple studies. This study tries to find how much the aerosols can affect evapo-transpiration (ET), a key component of the hydrological cycle over high NDVI (normalized difference vegetation index)/dense canopy, over Dibrugarh, known for vast tea plantation. The radiative effects of aerosols are calculated using satellite (Terra-MODIS) and reanalysis data on daily and monthly scales. Aerosol optical depth (AOD) obtained from satellite and ground observations compares well. Aerosol radiative forcing (ARF), calculated using MERRA data sets of 'clean-clear radiation' and 'clear-radiation' at the surface, shows a lower forcing efficiency, 35 Wm -zs , that is about half of that of ground observations. As vegetation controls ET over high NDVI area to the maximum and that gets modified through ARF, a regression equation is fitted between ET, AOD and NDVI for this station as ET = 0.25 + (-84.27) × AOD + (131.51) × NDVI that explains 82% of 'daily' ET variation using easily available satellite data. ET is found to follow net radiation closely and the direct relation between soil moisture and ET is weak on daily scale over this station as it may be acting through NDVI. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Top-of-atmosphere radiative forcing affected by brown carbon in the upper troposphere

    Science.gov (United States)

    Zhang, Yuzhong; Forrister, Haviland; Liu, Jiumeng; Dibb, Jack; Anderson, Bruce; Schwarz, Joshua P.; Perring, Anne E.; Jimenez, Jose L.; Campuzano-Jost, Pedro; Wang, Yuhang; Nenes, Athanasios; Weber, Rodney J.

    2017-07-01

    Carbonaceous aerosols affect the global radiative balance by absorbing and scattering radiation, which leads to warming or cooling of the atmosphere, respectively. Black carbon is the main light-absorbing component. A portion of the organic aerosol known as brown carbon also absorbs light. The climate sensitivity to absorbing aerosols rapidly increases with altitude, but brown carbon measurements are limited in the upper troposphere. Here we present aircraft observations of vertical aerosol distributions over the continental United States in May and June 2012 to show that light-absorbing brown carbon is prevalent in the troposphere, and absorbs more short-wavelength radiation than black carbon at altitudes between 5 and 12 km. We find that brown carbon is transported to these altitudes by deep convection, and that in-cloud heterogeneous processing may produce brown carbon. Radiative transfer calculations suggest that brown carbon accounts for about 24% of combined black and brown carbon warming effect at the tropopause. Roughly two-thirds of the estimated brown carbon forcing occurs above 5 km, although most brown carbon is found below 5 km. The highest radiative absorption occurred during an event that ingested a wildfire plume. We conclude that high-altitude brown carbon from biomass burning is an unappreciated component of climate forcing.

  19. Solar Radiation and Cloud Radiative Forcing in the Pacific Warm Pool Estimated Using TOGA COARE Measurements

    Science.gov (United States)

    Chou, Ming-Dah; Chou, Shu-Hsien; Zhao, Wenzhong

    1999-01-01

    The energy budget of the tropical western Pacific (TWP) is particularly important because this is one of the most energetic convection regions on the Earth. Nearly half of the solar radiation incident at the top of atmosphere is absorbed at the surface and only about 22% absorbed in the atmosphere. A large portion of the excess heat absorbed at the surface is transferred to the atmosphere through evaporation, which provides energy and water for convection and precipitation. The western equatorial Pacific is characterized by the highest sea surface temperature (SST) and heaviest rainfall in the world ocean. A small variation of SST associated with the eastward shift of the warm pool during El-Nino/Souther Oscillation changes the atmospheric circulation pattern and affects the global climate. In a study of the TWP surface heat and momentum fluxes during the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) Intensive observing period (IOP) from November 1992 to February have found that the solar radiation is the most important component of the surface energy budget, which undergoes significant temporal and spatial variation. The variations are influenced by the two 40-50 days Madden Julian Oscillations (MJOs) which propagated eastward from the Indian Ocean to the Central Pacific during the IOP. The TWP surface solar radiation during the COARE IOP was investigated by a number of studies. In addition, the effects of clouds on the solar heating of the atmosphere in the TWP was studied using energy budget analysis. In this study, we present some results of the TWP surface solar shortwave or SW radiation budget and the effect of clouds on the atmospheric solar heating using the surface radiation measurements and Japan's Geostationary Meteorological Satellite 4 radiance measurements during COARE IOP.

  20. Acoustic manipulation of active spherical carriers: Generation of negative radiation force

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, Majid, E-mail: majid_rajabi@iust.ac.ir; Mojahed, Alireza

    2016-09-15

    This paper examines theoretically a novel mechanism of generating negative (pulling) radiation force for acoustic manipulation of spherical carriers equipped with piezoelectric actuators in its inner surface. In this mechanism, the spherical particle is handled by common plane progressive monochromatic acoustic waves instead of zero-/higher- order Bessel beams or standing waves field. The handling strategy is based on applying a spatially uniform harmonic electrical voltage at the piezoelectric actuator with the same frequency of handling acoustic waves, in order to change the radiation force effect from repulsive (away from source) to attractive (toward source). This study may be considered as a start point for development of contact-free precise handling and entrapment technology of active carriers which are essential in many engineering and medicine applications.

  1. The Atmospheric Aerosols And Their Effects On Cloud Albedo And Radiative Forcing

    International Nuclear Information System (INIS)

    Stefan, S.; Iorga, G.; Zoran, M.

    2007-01-01

    The aim of this study is to provide results of the theoretical experiments in order to improve the estimates of indirect effect of aerosol on the cloud albedo and consequently on the radiative forcing. The cloud properties could be changed primarily because of changing of both the aerosol type and concentration in the atmosphere. Only a part of aerosol interacts effectively with water and will, in turn, determine the number concentration of cloud droplets (CDNC). We calculated the CDNC, droplet effective radius (reff), cloud optical thickness (or), cloud albedo and radiative forcing, for various types of aerosol. Our results show into what extent the change of aerosol characteristics (number concentration and chemical composition) on a regional scale can modify the cloud reflectivity. Higher values for cloud albedo in the case of the continental (urban) clouds were obtained

  2. Influence of Ice Particle Surface Roughening on the Global Cloud Radiative Effect

    Science.gov (United States)

    Yi, Bingqi; Yang, Ping; Baum, Bryan A.; LEcuyer, Tristan; Oreopoulos, Lazaros; Mlawer, Eli J.; Heymsfield, Andrew J.; Liou, Kuo-Nan

    2013-01-01

    Ice clouds influence the climate system by changing the radiation budget and large-scale circulation. Therefore, climate models need to have an accurate representation of ice clouds and their radiative effects. In this paper, new broadband parameterizations for ice cloud bulk scattering properties are developed for severely roughened ice particles. The parameterizations are based on a general habit mixture that includes nine habits (droxtals, hollow/solid columns, plates, solid/hollow bullet rosettes, aggregate of solid columns, and small/large aggregates of plates). The scattering properties for these individual habits incorporate recent advances in light-scattering computations. The influence of ice particle surface roughness on the ice cloud radiative effect is determined through simulations with the Fu-Liou and the GCM version of the Rapid Radiative Transfer Model (RRTMG) codes and the National Center for Atmospheric Research Community Atmosphere Model (CAM, version 5.1). The differences in shortwave (SW) and longwave (LW) radiative effect at both the top of the atmosphere and the surface are determined for smooth and severely roughened ice particles. While the influence of particle roughening on the single-scattering properties is negligible in the LW, the results indicate that ice crystal roughness can change the SW forcing locally by more than 10 W m(exp -2) over a range of effective diameters. The global-averaged SW cloud radiative effect due to ice particle surface roughness is estimated to be roughly 1-2 W m(exp -2). The CAM results indicate that ice particle roughening can result in a large regional SW radiative effect and a small but nonnegligible increase in the global LW cloud radiative effect.

  3. Jeans instability in collisional strongly coupled dusty plasma with radiative condensation and polarization force

    International Nuclear Information System (INIS)

    Prajapati, R. P.; Bhakta, S.; Chhajlani, R. K.

    2016-01-01

    The influence of dust-neutral collisions, polarization force, and electron radiative condensation is analysed on the Jeans (gravitational) instability of partially ionized strongly coupled dusty plasma (SCDP) using linear perturbation (normal mode) analysis. The Boltzmann distributed ions, dynamics of inertialess electrons, charged dust and neutral particles are considered. Using the plane wave solutions, a general dispersion relation is derived which is modified due to the presence of dust-neutral collisions, strong coupling effect, polarization force, electron radiative condensation, and Jeans dust/neutral frequencies. In the long wavelength perturbations, the Jeans instability criterion depends upon strong coupling effect, polarization interaction parameter, and thermal loss, but it is independent of dust-neutral collision frequency. The stability of the considered configuration is analysed using the Routh–Hurwitz criterion. The growth rates of Jeans instability are illustrated, and stabilizing influence of viscoelasticity and dust-neutral collision frequency while destabilizing effect of electron radiative condensation, polarization force, and Jeans dust-neutral frequency ratio is observed. This work is applied to understand the gravitational collapse of SCDP with dust-neutral collisions.

  4. Scenarios of Future Socio-Economics, Energy, Land Use, and Radiative Forcing

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Jiyong; Moss, Richard H.; Edmonds, James A.; Calvin, Katherine V.; Clarke, Leon E.; Dooley, James J.; Kim, Son H.; Kopp, Roberrt; Kyle, G. Page; Luckow, Patrick W.; Patel, Pralit L.; Thomson, Allison M.; Wise, Marshall A.; Zhou, Yuyu

    2013-04-13

    This chapter explores uncertainty in future scenarios of energy, land use, emissions and radiative forcing that span the range in the literature for radiative forcing, but also consider uncertainty in two other dimensions, challenges to mitigation and challenges to adaptation. We develop a set of six scenarios that we explore in detail including the underlying the context in which they are set, assumptions that drive the scenarios, the Global Change Assessment Model (GCAM), used to produce quantified implications for those assumptions, and results for the global energy and land-use systems as well as emissions, concentrations and radiative forcing. We also describe the history of scenario development and the present state of development of this branch of climate change research. We discuss the implications of alternative social, economic, demographic, and technology development possibilities, as well as potential stabilization regimes for the supply of and demand for energy, the choice of energy technologies, and prices of energy and agricultural commodities. Land use and land cover will also be discussed with the emphasis on the interaction between the demand for bioenergy and crops, crop yields, crop prices, and policy settings to limit greenhouse gas emissions.

  5. Comparison of radiative forcing impacts of the use of wood, peat, and fossil fuels

    International Nuclear Information System (INIS)

    Savolainen, I.; Hillebrand, K.; Nousiainen, I.; Sinisalo, J.

    1994-01-01

    The present study investigates the greenhouse impacts and the relevant time factors of the use of peat and wood for energy production and compares them with those of fossil fuels. Emissions and sinks of the whole energy production chain and subsequent use of the wood or peat production site are taken into account. The radiative forcing caused by energy production is used as a measure for the greenhouse impact. Economical considerations are not included. Radiative forcing is calculated for carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) emissions. The real emissions of energy production are calculated by subtracting the emissions of non-use from the emissions of energy production. All the emissions are given as a function of time, i.e. their evolution over time is taken into account. At this point the estimates for some emission developments are quite crude and should be considered exemplary. The studied energy production chains can be divided roughly into three groups, if the greenhouse impact caused by continuous energy production of hundred years is considered. In this case forest residues, planted stands and unused merchantable wood cause the least radiative forcing per unit of primary energy generated. Natural gas and peat from cultivated peatland form the middle group. According to the calculations coal and conventional peat cause the greatest greenhouse impact

  6. Loss tangent and complex modulus estimated by acoustic radiation force creep and shear wave dispersion.

    Science.gov (United States)

    Amador, Carolina; Urban, Matthew W; Chen, Shigao; Greenleaf, James F

    2012-03-07

    Elasticity imaging methods have been used to study tissue mechanical properties and have demonstrated that tissue elasticity changes with disease state. In current shear wave elasticity imaging methods typically only shear wave speed is measured and rheological models, e.g. Kelvin-Voigt, Maxwell and Standard Linear Solid, are used to solve for tissue mechanical properties such as the shear viscoelastic complex modulus. This paper presents a method to quantify viscoelastic material properties in a model-independent way by estimating the complex shear elastic modulus over a wide frequency range using time-dependent creep response induced by acoustic radiation force. This radiation force induced creep method uses a conversion formula that is the analytic solution of a constitutive equation. The proposed method in combination with shearwave dispersion ultrasound vibrometry is used to measure the complex modulus so that knowledge of the applied radiation force magnitude is not necessary. The conversion formula is shown to be sensitive to sampling frequency and the first reliable measure in time according to numerical simulations using the Kelvin-Voigt model creep strain and compliance. Representative model-free shear complex moduli from homogeneous tissue mimicking phantoms and one excised swine kidney were obtained. This work proposes a novel model-free ultrasound-based elasticity method that does not require a rheological model with associated fitting requirements.

  7. Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC.

    Science.gov (United States)

    Brühl, C; Lelieveld, J; Tost, H; Höpfner, M; Glatthor, N

    2015-03-16

    Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO 2 , the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO 2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO 2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO 2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m 2 . For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m 2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m 2 , leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions.

  8. Origin and radiative forcing of black carbon aerosol: production and consumption perspectives.

    Science.gov (United States)

    Meng, Jing; Liu, Junfeng; Yi, Kan; Yang, Haozhe; Guan, Dabo; Liu, Zhu; Zhang, Jiachen; Ou, Jiamin; Dorling, Stephen; Mi, Zhifu; Shen, Huizhong; Zhong, Qirui; Tao, Shu

    2018-04-24

    Air pollution, a threat to air quality and human health, has attracted ever-increasing attention in recent years. In addition to having local influence, air pollutants can also travel the globe via atmospheric circulation and international trade. Black carbon (BC), emitted from incomplete combustion, is a unique but representative particulate pollutant. This study tracked down the BC aerosol and its direct radiative forcing to the emission sources and final consumers using the global chemical transport model (MOZART-4), the rapid radiative transfer model for general circulation simulations (RRTM) and a multiregional input-output analysis (MRIO). BC is physically transported (i.e., atmospheric transport) from western to eastern countries in the mid-latitude westerlies, but its magnitude is near an order of magnitude higher if the virtual flow embodied in international trade is considered. The transboundary effects on East and South Asia by other regions increased from about 3% (physical transport only) to 10% when considering both physical and virtual transport. The influence efficiency on East Asia is also large because of the comparatively large emission intensity and emission-intensive exports (e.g., machinery and equipment). The radiative forcing in Africa imposed by consumption from Europe, North America and East Asia (0.01Wm-2) was even larger than the total forcing in North America. Understanding the supply chain and incorporating both atmospheric and virtual transport may improve multilateral cooperation on air pollutant mitigation both domestically and internationally.

  9. Toric focusing for radiation force applications using a toric lens coupled to a spherically focused transducer.

    Science.gov (United States)

    Arnal, Bastien; Nguyen, Thu-Mai; O'Donnell, Matthew

    2014-12-01

    Dynamic elastography using radiation force requires that an ultrasound field be focused during hundreds of microseconds at a pressure of several megapascals. Here, we address the importance of the focal geometry. Although there is usually no control of the elevational focal width in generating a tissue mechanical response, we propose a tunable approach to adapt the focus geometry that can significantly improve radiation force efficiency. Several thin, in-house-made polydimethylsiloxane lenses were designed to modify the focal spot of a spherical transducer. They exhibited low absorption and the focal spot widths were extended up to 8-fold in the elevation direction. Radiation force experiments demonstrated an 8-fold increase in tissue displacements using the same pressure level in a tissue-mimicking phantom with a similar shear wave spectrum, meaning it does not affect elastography resolution. Our results demonstrate that larger tissue responses can be obtained for a given pressure level, or that similar response can be reached at a much lower mechanical index (MI). We envision that this work will impact 3-D elastography using 2-D phased arrays, where such shaping can be achieved electronically with the potential for adaptive optimization.

  10. Acoustic radiation force on a multilayered sphere in a Gaussian standing field

    Science.gov (United States)

    Wang, Haibin; Liu, Xiaozhou; Gao, Sha; Cui, Jun; Liu, Jiehui; He, Aijun; Zhang, Gutian

    2018-03-01

    We develop a model for calculating the radiation force on spherically symmetric multilayered particles based on the acoustic scattering approach. An expression is derived for the radiation force on a multilayered sphere centered on the axis of a Gaussian standing wave propagating in an ideal fluid. The effects of the sound absorption of the materials and sound wave on acoustic radiation force of a multilayered sphere immersed in water are analyzed, with particular emphasis on the shell thickness of every layer, and the width of the Gaussian beam. The results reveal that the existence of particle trapping behavior depends on the choice of the non-dimensional frequency ka, as well as the shell thickness of each layer. This study provides a theoretical basis for the development of acoustical tweezers in a Gaussian standing wave, which may benefit the improvement and development of acoustic control technology, such as trapping, sorting, and assembling a cell, and drug delivery applications. Project supported by National Key R&D Program (Grant No. 2016YFF0203000), the National Natural Science Foundation of China (Grant Nos. 11774167 and 61571222), the Fundamental Research Funds for the Central Universities of China (Grant No. 020414380001), the Key Laboratory of Underwater Acoustic Environment, Institute of Acoustics, Chinese Academy of Sciences (Grant No. SSHJ-KFKT-1701), and the AQSIQ Technology R&D Program of China (Grant No. 2017QK125).

  11. Implications of Representative Concentration Pathway 4.5 Methane Emissions to Stabilize Radiative Forcing

    Energy Technology Data Exchange (ETDEWEB)

    Emanuel, William R.; Janetos, Anthony C.

    2013-02-01

    Increases in the abundance of methane (CH4) in the Earth’s atmosphere are responsible for significant radiative forcing of climate change (Forster et al., 2007; Wuebbles and Hayhoe, 2002). Since 1750, a 2.5 fold increase in atmospheric CH4 contributed 0.5 W/m2 to direct radiative forcing and an additional 0.2 W/m2 indirectly through changes in atmospheric chemistry. Next to water and carbon dioxide (CO2), methane is the most abundant greenhouse gas in the troposphere. Additionally, CH4 is significantly more effective as a greenhouse gas on a per molecule basis than is CO2, and increasing atmospheric CH4 has been second only to CO2 in radiative forcing (Forster et al., 2007). The chemical reactivity of CH4 is important to both tropospheric and stratospheric chemistry. Along with carbon monoxide, methane helps control the amount of the hydroxyl radical (OH) in the troposphere where oxidation of CH4 by OH leads to the formation of formaldehyde, carbon monoxide, and ozone.

  12. The Impact of Desert Dust Aerosol Radiative Forcing on Global and West African Precipitation

    Science.gov (United States)

    Jordan, A.; Zaitchik, B. F.; Gnanadesikan, A.; Dezfuli, A. K.

    2015-12-01

    Desert dust aerosols exert a radiative forcing on the atmosphere, influencing atmospheric temperature structure and modifying radiative fluxes at the top of the atmosphere (TOA) and surface. As dust aerosols perturb radiative fluxes, the atmosphere responds by altering both energy and moisture dynamics, with potentially significant impacts on regional and global precipitation. Global Climate Model (GCM) experiments designed to characterize these processes have yielded a wide range of results, owing to both the complex nature of the system and diverse differences across models. Most model results show a general decrease in global precipitation, but regional results vary. Here, we compare simulations from GFDL's CM2Mc GCM with multiple other model experiments from the literature in order to investigate mechanisms of radiative impact and reasons for GCM differences on a global and regional scale. We focus on West Africa, a region of high interannual rainfall variability that is a source of dust and that neighbors major Sahara Desert dust sources. As such, changes in West African climate due to radiative forcing of desert dust aerosol have serious implications for desertification feedbacks. Our CM2Mc results show net cooling of the planet at TOA and surface, net warming of the atmosphere, and significant increases in precipitation over West Africa during the summer rainy season. These results differ from some previous GCM studies, prompting comparative analysis of desert dust parameters across models. This presentation will offer quantitative analysis of differences in dust aerosol parameters, aerosol optical properties, and overall particle burden across GCMs, and will characterize the contribution of model differences to the uncertainty of forcing and climate response affecting West Africa.

  13. Radiation-reaction force on a small charged body to second order

    Science.gov (United States)

    Moxon, Jordan; Flanagan, Éanna

    2018-05-01

    In classical electrodynamics, an accelerating charged body emits radiation and experiences a corresponding radiation-reaction force, or self-force. We extend to higher order in the total charge a previous rigorous derivation of the electromagnetic self-force in flat spacetime by Gralla, Harte, and Wald. The method introduced by Gralla, Harte, and Wald computes the self-force from the Maxwell field equations and conservation of stress-energy in a limit where the charge, size, and mass of the body go to zero, and it does not require regularization of a singular self-field. For our higher-order computation, an adjustment of the definition of the mass of the body is necessary to avoid including self-energy from the electromagnetic field sourced by the body in the distant past. We derive the evolution equations for the mass, spin, and center-of-mass position of the body through second order. We derive, for the first time, the second-order acceleration dependence of the evolution of the spin (self-torque), as well as a mixing between the extended body effects and the acceleration-dependent effects on the overall body motion.

  14. DOE Task Force meeting on Electrical Breakdown of Insulating Ceramics in a High Radiation Field

    International Nuclear Information System (INIS)

    Green, P.H.

    1991-08-01

    This volume contains the abstracts and presentation material from the Research Assistance Task Force Meeting ''Electrical Breakdown of Insulating Ceramics in a High-Radiation Field.'' The meeting was jointly sponsored by the Office of Basic Energy Sciences and the Office of Fusion Energy of the US Department of Energy in Vail, Colorado, May 28--June 1, 1991. The 26 participants represented expertise in fusion, radiation damage, electrical breakdown, ceramics, and semiconductor and electronic structures. These participants came from universities, industries, national laboratories, and government. The attendees represented eight nations. The Task Force meeting was organized in response to the recent discovery that a combination of temperature, electric field, and radiation for an extended period of time has an unexplained adverse effect in ceramics, termed radiation-enhanced electrical degradation (REED). REED occurs after an incubation period and continues to accelerate with irradiation until the ceramics can no longer be regarded as insulators. It appears that REED is irreversible and the ceramic insulators cannot be readily annealed or otherwise repaired for future services. This effect poses a serious threat for fusion reactors, which require electrical insulators in diagnostic devices, in radio frequency and neutral beam systems, and in magnetic assemblies. The problem of selecting suitable electrical insulating materials in thus far more serious than previously anticipated

  15. Effect of magnetic field and radiative condensation on the Jeans instability of dusty plasma with polarization force

    International Nuclear Information System (INIS)

    Prajapati, R.P.

    2013-01-01

    The Jeans instability of self-gravitating dusty plasma with polarization force is investigated considering the effects of magnetic field, dust temperature and radiative condensation. The condition of Jeans instability and expression of critical Jeans wave number are obtained which depend upon polarization force and dust temperature but these are unaffected by the presence of magnetic field. The radiative heat-loss functions also modify the Jeans condition of instability and expression of critical Jeans wave number. It is observed that the polarization force and ratio of radiative heat-loss functions have destabilizing while magnetic field and dust temperature have stabilizing influence on the growth rate of Jeans instability.

  16. The outflows accelerated by the magnetic fields and radiation force of accretion disks

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xinwu, E-mail: cxw@shao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 (China)

    2014-03-01

    The inner region of a luminous accretion disk is radiation-pressure-dominated. We estimate the surface temperature of a radiation-pressure-dominated accretion disk, Θ=c{sub s}{sup 2}/r{sup 2}Ω{sub K}{sup 2}≪(H/r){sup 2}, which is significantly lower than that of a gas-pressure-dominated disk, Θ ∼ (H/r){sup 2}. This means that the outflow can be launched magnetically from the photosphere of the radiation-pressure-dominated disk only if the effective potential barrier along the magnetic field line is extremely shallow or no potential barrier is present. For the latter case, the slow sonic point in the outflow will probably be in the disk, which leads to a slow circular dense flow above the disk. This implies that hot gas (probably in the corona) is necessary for launching an outflow from the radiation-pressure-dominated disk, which provides a natural explanation for the observational evidence that the relativistic jets are related to hot plasma in some X-ray binaries and active galactic nuclei. We investigate the outflows accelerated from the hot corona above the disk by the magnetic field and radiation force of the accretion disk. We find that with the help of the radiation force, the mass loss rate in the outflow is high, which leads to a slow outflow. This may be why the jets in radio-loud narrow-line Seyfert galaxies are in general mildly relativistic compared with those in blazars.

  17. Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED summer 2013 campaign

    Directory of Open Access Journals (Sweden)

    M. Mallet

    2016-01-01

    direct forcing, in situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the aerosol direct radiative forcing (DRF. Results show significant surface SW instantaneous forcing (up to −90 W m−2 at noon. Aircraft observations provide also original estimates of the vertical structure of SW and LW radiative heating revealing significant instantaneous values of about 5° K per day in the solar spectrum (for a solar angle of 30° within the dust layer. Associated 3-D modeling studies from regional climate (RCM and chemistry transport (CTM models indicate a relatively good agreement for simulated AOD compared with observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky surface DRF indicate an average of about −10 to −20 W m−2 (for the whole period over the Mediterranean Sea together with maxima (−50 W m−2 over northern Africa. The top of the atmosphere (TOA DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa. Finally, a multi-year simulation, performed for the 2003 to 2009 period and including an ocean–atmosphere (O–A coupling, underlines the impact of the aerosol direct radiative forcing on the sea surface temperature, O–A fluxes and the hydrological cycle over the Mediterranean.

  18. On the relationship between aerosol model uncertainty and radiative forcing uncertainty.

    Science.gov (United States)

    Lee, Lindsay A; Reddington, Carly L; Carslaw, Kenneth S

    2016-05-24

    The largest uncertainty in the historical radiative forcing of climate is caused by the interaction of aerosols with clouds. Historical forcing is not a directly measurable quantity, so reliable assessments depend on the development of global models of aerosols and clouds that are well constrained by observations. However, there has been no systematic assessment of how reduction in the uncertainty of global aerosol models will feed through to the uncertainty in the predicted forcing. We use a global model perturbed parameter ensemble to show that tight observational constraint of aerosol concentrations in the model has a relatively small effect on the aerosol-related uncertainty in the calculated forcing between preindustrial and present-day periods. One factor is the low sensitivity of present-day aerosol to natural emissions that determine the preindustrial aerosol state. However, the major cause of the weak constraint is that the full uncertainty space of the model generates a large number of model variants that are equally acceptable compared to present-day aerosol observations. The narrow range of aerosol concentrations in the observationally constrained model gives the impression of low aerosol model uncertainty. However, these multiple "equifinal" models predict a wide range of forcings. To make progress, we need to develop a much deeper understanding of model uncertainty and ways to use observations to constrain it. Equifinality in the aerosol model means that tuning of a small number of model processes to achieve model-observation agreement could give a misleading impression of model robustness.

  19. Tropospheric Aerosol Radiative Forcing Observational eXperiment - University of Washington instrumented C-131A aircraft Data Set

    Data.gov (United States)

    National Aeronautics and Space Administration — TARFOX_UWC131A is the Tropospheric Aerosol Radiative Forcing Observational eXperiment (TARFOX) - University of Washington instrumented C-131A aircraft data set. The...

  20. Satellite observed impacts of wildfires on regional atmosphere composition and shortwave radiative forcing: multiple cases study

    Science.gov (United States)

    Fu, Y.; Li, R.; Huang, J.; Bergeron, Y.; Fu, Y.

    2017-12-01

    Emissions of aerosols and trace gases from wildfires and the direct shortwave radiative forcing were studied using multi-satellite/sensor observations from Aqua Moderate-Resolution Imaging Spectroradiometer (MODIS), Aqua Atmospheric Infrared Sounder (AIRS), Aura Ozone Monitoring Instrument (OMI), and Aqua Cloud's and the Earth's Radiant Energy System (CERES). The selected cases occurred in Northeast of China (NEC), Siberia of Russia, California of America have dominant fuel types of cropland, mixed forest and needleleaf forest, respectively. The Fire radiative power (FRP) based emission coefficients (Ce) of aerosol, NOx (NO2+NO), formaldehyde (HCHO), and carbon monoxide (CO) showed significant differences from case to case. 1) the FRP of the cropland case in NEC is strongest, however, the Ce of aerosol is the lowest (20.51 ± 2.55 g MJ-1). The highest Ce of aerosol is 71.34 ± 13.24 g MJ-1 in the needleleaf fire case in California. 2) For NOx, the highest Ce existed in the cropland case in NEC (2.76 ± 0.25 g MJ-1), which is more than three times of those in the forest fires in Siberia and California. 3) The Ce of CO is 70.21±10.97 and 88.38±46.16 g MJ-1 in the forest fires in Western Siberia and California, which are about four times of that in cropland fire. 4) The variation of Ce of HCHO are relatively small among cases. Strong spatial correlations are found among aerosol optical depth (AOD), NOx, HCHO, and CO. The ratios of NOx to AOD, HCHO, and CO in the cropland case in NEC show much higher values than those in other cases. Although huge differences of emissions and composition ratios exist among cases, the direct shortwave (SW) radiative forcing efficiency (SWARFE) of smoke at the top of the atmosphere (TOA) are in good agreement, with the shortwave radiative forcing efficiencies values of 20.09 to 22.93 per unit AOD. Results in this study reveal noteworthy variations of the FRP-based emissions coefficient and relative chemical composition in the smoke

  1. Long-term in vivo survival of Rh(D)-negative donor red cells in a patient with anti-LW

    International Nuclear Information System (INIS)

    Chaplin, H.; Hunter, V.L.; Rosche, M.E.; Shirey, R.S.

    1985-01-01

    The present study documents immediate and long-term survival of crossmatch-incompatible Rh(D)-negative donor red cells in a patient with anti-LW. A 67-year-old group A Rh(D)-positive man was admitted for urgent coronary artery bypass surgery. The direct antiglobulin test (DAT) was weakly positive in two of five laboratories. His serum contained anti-LW (two laboratories); his red cells were LW negative (three antisera). Two siblings were LW-positive. Surgery was delayed, and 3 ml Rh(D)-negative crossmatch-incompatible red cells stored in citrate-phosphate-dextrose-adenine-one were labeled with 25 microCi of 51 Cr and injected. Immediate survival was approximately 100 percent with 92 percent survival at 20 hours. Six daily blood samples showed a decreased red cell lifespan, (T 1/2 . 14 days). Because of medical complications, 4 units of Rh(D)-negative crossmatch-incompatible blood were then transfused without clinical or hemolytic reaction. The anti-IgG DAT became stronger. In vivo survival of the remaining 51 Cr-RBCs became normal (T 1/2 28 days over the succeeding 20 days). Following transfusion, no change in serum antibody strength was demonstrated by double-blind titration of seven coded samples. The observations support modest reduction of lifespan for 3 ml of LW-positive red cells, but normal survival following subsequent transfusion of approximately 700 ml of LW-positive red cells

  2. Temperature rise, sea level rise and increased radiative forcing - an application of cointegration methods

    Science.gov (United States)

    Schmith, Torben; Thejll, Peter; Johansen, Søren

    2016-04-01

    We analyse the statistical relationship between changes in global temperature, global steric sea level and radiative forcing in order to reveal causal relationships. There are in this, however, potential pitfalls due to the trending nature of the time series. We therefore apply a statistical method called cointegration analysis, originating from the field of econometrics, which is able to correctly handle the analysis of series with trends and other long-range dependencies. Further, we find a relationship between steric sea level and temperature and find that temperature causally depends on the steric sea level, which can be understood as a consequence of the large heat capacity of the ocean. This result is obtained both when analyzing observed data and data from a CMIP5 historical model run. Finally, we find that in the data from the historical run, the steric sea level, in turn, is driven by the external forcing. Finally, we demonstrate that combining these two results can lead to a novel estimate of radiative forcing back in time based on observations.

  3. Calculations of Aerosol Radiative Forcing in the SAFARI Region from MODIS Data

    Science.gov (United States)

    Remer, L. A.; Ichoku, C.; Kaufman, Y. J.; Chu, D. A.

    2003-01-01

    SAFARI 2000 provided the opportunity to validate MODIS aerosol retrievals and to correct any assumptions in the retrieval process. By comparing MODIS retrievals with ground-based sunphotometer data, we quantified the degree to which the MODIS algorithm underestimated the aerosol optical thickness. This discrepancy was attributed to underestimating the degree of light absorption by the southern African smoke aerosol. Correcting for this underestimation of absorption, produces more realistic aerosol retrievals that allow various applications of the MODIS aerosol products. One such application is the calculation of the aerosol radiative forcing at the top and bottom of the atmosphere. The combination of MODIS accuracy, coverage, resolution and the ability to separate fine and coarse mode make this calculation substantially advanced over previous attempts with other satellites. We focus on the oceans adjacent to southern Africa and use a solar radiative transfer model to perform the flux calculations. The forcing at the top of atmosphere is calculated to be 10 W/sq m, while the forcing at the surface is -26 W/sq m. These results resemble those calculated from INDOEX data, and are most sensitive to assumptions of aerosol absorption, the same parameter that initially interfered with our retrievals.

  4. Radiative forcing associated with particulate carbon emissions resulting from the use of mercury control technology.

    Science.gov (United States)

    Lin, Guangxing; Penner, Joyce E; Clack, Herek L

    2014-09-02

    Injection of powdered activated carbon (PAC) adsorbents into the flue gas of coal fired power plants with electrostatic precipitators (ESPs) is the most mature technology to control mercury emissions for coal combustion. However, the PAC itself can penetrate ESPs to emit into the atmosphere. These emitted PACs have similar size and optical properties to submicron black carbon (BC) and thus could increase BC radiative forcing unintentionally. The present paper estimates, for the first time, the potential emission of PAC together with their climate forcing. The global average maximum potential emissions of PAC is 98.4 Gg/yr for the year 2030, arising from the assumed adoption of the maximum potential PAC injection technology, the minimum collection efficiency, and the maximum PAC injection rate. These emissions cause a global warming of 2.10 mW m(-2) at the top of atmosphere and a cooling of -2.96 mW m(-2) at the surface. This warming represents about 2% of the warming that is caused by BC from direct fossil fuel burning and 0.86% of the warming associated with CO2 emissions from coal burning in power plants. Its warming is 8 times more efficient than the emitted CO2 as measured by the 20-year-integrated radiative forcing per unit of carbon input (the 20-year Global Warming Potential).

  5. The Effect of Asian Dust Aerosols on Cloud Properties and Radiative Forcing from MODIS and CERES

    Science.gov (United States)

    Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

    2005-01-01

    The effects of dust storms on cloud properties and radiative forcing are analyzed over northwestern China from April 2001 to June 2004 using data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of the cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. The humidity differences are larger in the dusty region than in the dust-free region, and may be caused by removal of moisture by wet dust precipitation. Due to changes in cloud microphysics, the instantaneous net radiative forcing is reduced from -71.2 W/m2 for dust contaminated clouds to -182.7 W/m2 for dust-free clouds. The reduced cooling effects of dusts may lead to a net warming of 1 W/m2, which, if confirmed, would be the strongest aerosol forcing during later winter and early spring dust storm seasons over the studied region.

  6. Host model uncertainties in aerosol radiative forcing estimates: results from the AeroCom Prescribed intercomparison study

    Directory of Open Access Journals (Sweden)

    P. Stier

    2013-03-01

    Full Text Available Simulated multi-model "diversity" in aerosol direct radiative forcing estimates is often perceived as a measure of aerosol uncertainty. However, current models used for aerosol radiative forcing calculations vary considerably in model components relevant for forcing calculations and the associated "host-model uncertainties" are generally convoluted with the actual aerosol uncertainty. In this AeroCom Prescribed intercomparison study we systematically isolate and quantify host model uncertainties on aerosol forcing experiments through prescription of identical aerosol radiative properties in twelve participating models. Even with prescribed aerosol radiative properties, simulated clear-sky and all-sky aerosol radiative forcings show significant diversity. For a purely scattering case with globally constant optical depth of 0.2, the global-mean all-sky top-of-atmosphere radiative forcing is −4.47 Wm−2 and the inter-model standard deviation is 0.55 Wm−2, corresponding to a relative standard deviation of 12%. For a case with partially absorbing aerosol with an aerosol optical depth of 0.2 and single scattering albedo of 0.8, the forcing changes to 1.04 Wm−2, and the standard deviation increases to 1.01 W−2, corresponding to a significant relative standard deviation of 97%. However, the top-of-atmosphere forcing variability owing to absorption (subtracting the scattering case from the case with scattering and absorption is low, with absolute (relative standard deviations of 0.45 Wm−2 (8% clear-sky and 0.62 Wm−2 (11% all-sky. Scaling the forcing standard deviation for a purely scattering case to match the sulfate radiative forcing in the AeroCom Direct Effect experiment demonstrates that host model uncertainties could explain about 36% of the overall sulfate forcing diversity of 0.11 Wm−2 in the AeroCom Direct Radiative Effect experiment. Host model errors in aerosol radiative forcing are largest in regions of uncertain host model

  7. Retention and radiative forcing of black carbon in eastern Sierra Nevada snow

    Directory of Open Access Journals (Sweden)

    K. M. Sterle

    2013-02-01

    Full Text Available When contaminated by absorbing particles, such as refractory black carbon (rBC and continental dust, snow's albedo decreases and thus its absorption of solar radiation increases, thereby hastening snowmelt. For this reason, an understanding of rBC's affect on snow albedo, melt processes, and radiation balance is critical for water management, especially in a changing climate. Measurements of rBC in a sequence of snow pits and surface snow samples in the eastern Sierra Nevada of California during the snow accumulation and ablation seasons of 2009 show that concentrations of rBC were enhanced sevenfold in surface snow (~25 ng g–1 compared to bulk values in the snowpack (~3 ng g–1. Unlike major ions, which were preferentially released during the initial melt, rBC and continental dust were retained in the snow, enhancing concentrations well into late spring, until a final flush occurred during the ablation period. We estimate a combined rBC and continental dust surface radiative forcing of 20 to 40 W m−2 during April and May, with dust likely contributing a greater share of the forcing.

  8. Source attribution of black carbon and its direct radiative forcing in China

    International Nuclear Information System (INIS)

    Yang, Yang; Wang, Hailong; Ma, Po-Lun; Rasch, Philip J.; Smith, Steven J.

    2017-01-01

    The source attributions for mass concentration, haze formation, transport and direct radiative forcing of black carbon (BC) in various regions of China are quantified in this study using the Community Earth System Model (CESM) with a source-tagging technique. Anthropogenic emissions are from the Community Emissions Data System that is newly developed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Over north China where the air quality is often poor, about 90 % of near-surface BC concentration is contributed by local emissions. Overall, 35 % of BC concentration over south China in winter can be attributed to emissions from north China, and 19 % comes from sources outside China in spring. For other regions in China, BC is largely contributed from nonlocal sources. We further investigated potential factors that contribute to the poor air quality in China. During polluted days, a net inflow of BC transported from nonlocal source regions associated with anomalous winds plays an important role in increasing local BC concentrations. BC-containing particles emitted from East Asia can also be transported across the Pacific. Our model results show that emissions from inside and outside China are equally important for the BC outflow from East Asia, while emissions from China account for 8 % of BC concentration and 29 % in column burden in the western United States in spring. Radiative forcing estimates show that 65 % of the annual mean BC direct radiative forcing (2.2 W m -2 ) in China results from local emissions, and the remaining 35 % is contributed by emissions outside of China. Efficiency analysis shows that a reduction in BC emissions over eastern China could have a greater benefit for the regional air quality in China, especially in the winter haze season.

  9. Impact of Two Intense Dust Storms on Aerosol Characteristics and Radiative Forcing over Patiala, Northwestern India

    Directory of Open Access Journals (Sweden)

    Deepti Sharma

    2012-01-01

    Full Text Available Impact of dust storms on the aerosol characteristics and radiative forcing over Patiala, northwestern India has been studied during April-June of 2010 using satellite observations and ground-based measurements. Six dust events (DE have been identified during the study period with average values of Aqua-MODIS AOD550 and Microtops-II AOD500 over Patiala as 1.00±0.51 and 0.84±0.41, respectively while Aura-OMI AI exhibits high values ranging from 2.01 to 6.74. The Ångström coefficients α380–870 and β range from 0.12 to 0.31 and 0.95 to 1.40, respectively. The measured spectral AODs, the OPAC-derived aerosol properties and the surface albedo obtained from MODIS were used as main inputs in SBDART model for the calculation of aerosol radiative forcing (ARF over Patiala. The ARF at surface (SRF and top of atmosphere (TOA ranges from ∼−50 to −100 Wm−2 and from ∼−10 to −25 Wm−2, respectively during the maximum of dust storms. The radiative forcing efficiency was found to be −66 Wm−2AOD−1 at SRF and −14 Wm−2AOD−1 at TOA. High values of ARF in the atmosphere (ATM, ranging between ∼+40 Wm−2 and +80.0 Wm−2 during the DE days, might have significant effect on the warming of the lower and middle atmosphere and, hence, on climate over northwestern India.

  10. The model evaluation of subsonic aircraft effect on the ozone and radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Rozanov, E; Zubov, V; Egorova, T; Ozolin, Y [Main Geophysical Observatory, St.Petersburg (Russian Federation)

    1998-12-31

    Two dimensional transient zonally averaged model was used for the evaluation of the effect of subsonic aircraft exhausts upon the ozone, trace gases and radiation in the troposphere and lower stratosphere. The mesoscale transformation of gas composition was included on the base of the box model simulations. It has been found that the transformation of the exhausted gases in sub-grid scale is able to influence the results of the modelling. The radiative forcing caused by gas, sulfate aerosol, soot and contrails changes was estimated as big as 0.12-0.15 W/m{sup 2} (0.08 W/m{sup 2} globally and annually averaged). (author) 10 refs.

  11. The model evaluation of subsonic aircraft effect on the ozone and radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Rozanov, E.; Zubov, V.; Egorova, T.; Ozolin, Y. [Main Geophysical Observatory, St.Petersburg (Russian Federation)

    1997-12-31

    Two dimensional transient zonally averaged model was used for the evaluation of the effect of subsonic aircraft exhausts upon the ozone, trace gases and radiation in the troposphere and lower stratosphere. The mesoscale transformation of gas composition was included on the base of the box model simulations. It has been found that the transformation of the exhausted gases in sub-grid scale is able to influence the results of the modelling. The radiative forcing caused by gas, sulfate aerosol, soot and contrails changes was estimated as big as 0.12-0.15 W/m{sup 2} (0.08 W/m{sup 2} globally and annually averaged). (author) 10 refs.

  12. Radiation forcing by the atmospheric aerosols in the nocturnal boundary layer

    Science.gov (United States)

    Singh, D. K.; Ponnulakshami, V. K.; Mukund, V.; Subramanian, G.; Sreenivas, K. R.

    2013-05-01

    We have conducted experimental and theoretical studies on the radiation forcing due to suspended aerosols in the nocturnal boundary layer. We present radiative, conductive and convective equilibrium profile for different bottom boundaries where calculated Rayleigh number is higher than the critical Rayleigh number in laboratory conditions. The temperature profile can be fitted using an exponential distribution of aerosols concentration field. We also present the vertical temperature profiles in a nocturnal boundary in the presence of fog in the field. Our results show that during the presence of fog in the atmosphere, the ground temperature is greater than the dew-point temperature. The temperature profiles before and after the formation of fog are also observed to be different.

  13. Acoustical radiation torque and force for spheres and Bessel beam extinction efficiency

    Science.gov (United States)

    Marston, Philip L.; Zhang, Likun

    2014-11-01

    The scattering of optical and acoustical beams is relevant to the levitation and manipulation of drops. Here we examine theoretical developments in the acoustical case. We previously showed how the optical theorem for extinction can be extended to invariant beams. The example of a sphere in a Bessel beam facilitates the direct comparison with a circular disc computed using Babinet's principle and the Kirchhoff approximation. In related work, by considering traveling or standing wave first-order vortex beams we previously showed that the radiation torque is the ratio of the absorbed power and the radian acoustic frequency. By modifying the scattering to account for the viscosity of the surrounding fluid in the analysis of the absorbed power, approximations for radiation torque and force are obtained at long wavelengths in special cases and these can be compared with results published elsewhere.

  14. Estimation of mechanical properties of gelatin using a microbubble under acoustic radiation force

    International Nuclear Information System (INIS)

    Shirota, Eriko; Ando, Keita

    2015-01-01

    This paper is concerned with observations of the translation of a microbubble (80 μm or 137 μm in radius) in a viscoelastic medium (3 w% gelatin), which is induced by acoustic radiation force originating from 1 MHz focused ultrasound. An optical system using a high-speed camera was designed to visualize the bubble translation and deformation. If the bubble remains its spherical shape under the sonication, the bubble translation we observed can be described by theory based on the Voigt model for linear viscoelastic solids; mechanical properties of the gelatin are calculated from measurements of the terminal displacement under the sonication. (paper)

  15. Greenhouse gases, radiative forcing, global warming potential and waste management – an introduction

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Kjeldsen, Peter; Gentil, Emmanuel

    2009-01-01

    forcing (RF) and global warming potential (GWP). This paper provides a general introduction of the factors that define a GHG and explains the scientific background for estimating RF and GWP, thereby exposing the lay reader to a brief overview of the methods for calculating the effects of GHGs on climate......Management of post-consumer solid waste contributes to emission of greenhouse gases (GHGs) representing about 3% of global anthropogenic GHG emissions. Most GHG reporting initiatives around the world utilize two metrics proposed by the Intergovernmental Panel on Climate Change (IPCC): radiative...

  16. Health physics experience with nondestructive X-radiation facilities in the US Air Force

    International Nuclear Information System (INIS)

    Stencel, J.R.; Piltingsrud, H.V.

    1976-01-01

    Radiation safety experience in the construction and use of enclosed nondestructive inspection (NDI) facilities in the US Air Force, has reaffirmed the constant need for the health physicist to continually monitor and assit in upgrading these facilities. Health physics contributions include evaluation of initial shielding requirements, proper selection of construction material, insuring that adequate safety devices are installed and adequate personnel dosimetry devices are available, surveying the facility, and assisting in the safety education program. There is a need to better define NDI warning/safety devices, using the National Bureau of Standards, (NBS) Handbook 107 as the most applicable guide

  17. Monthly and seasonal variations of aerosol optical properties and direct radiative forcing over Zanjan, Iran

    Science.gov (United States)

    Gharibzadeh, Maryam; Alam, Khan; Abedini, Yousefali; Bidokhti, Abbasali Aliakbari; Masoumi, Amir

    2017-11-01

    Aerosol optical properties and radiative forcing over Zanjan in northwest of Iran has been analyzed during 2010-2013. The aerosol optical and radiative properties are less studied over Zanjan, and therefore, require a careful and in depth analysis. The optical properties like Aerosol Optical Depth (AOD), Ångström Exponent (AE), ASYmmetry parameter (ASY), Single Scattering Albedo (SSA), and Aerosol Volume Size Distribution (AVSD) have been evaluated using the ground-based AErosol RObotic NETwork (AERONET) data. Higher AOD while relatively lower AE were observed in the spring and summer, which showed the presence of coarse mode particles in these seasons. An obvious increase of coarse mode particles in AVSD distribution, as well as a higher value of SSA represented considerable addition of coarse mode particles like dust into the atmosphere of Zanjan in these two seasons. Increase in AE, while a decrease in AOD was detected in the winter and fall. The presence of fine particles indicates the dominance of particles like urban-industrial aerosols from local sources especially in the winter. The Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model was utilized to calculate the Aerosol Radiative Forcing (ARF) at the Top of the Atmosphere (TOA), earth's surface and within the atmosphere. The annual averaged ARF values were -13.47 W m-2 and -36.1 W m-2 at the TOA and earth's surface, respectively, which indicate a significant cooling effect. Likewise, the ARF efficiencies at the TOA and earth's surface were -65.08 W m-2 and -158.43 W m-2, respectively. The annual mean atmospheric ARF and heating rate within the atmosphere were 22.63 W m-2 and 0.27 Kday-1 respectively, represented the warming effect within the atmosphere. Finally, a good agreement was found between AERONET retrieved ARF and SBDART simulated ARF.

  18. Interannual Variability in Dust Deposition, Radiative Forcing, and Snowmelt Rates in the Colorado River Basin

    Science.gov (United States)

    Skiles, M.; Painter, T. H.; Deems, J. S.; Barrett, A. P.

    2011-12-01

    Dust in snow accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. Since the Anglo expansion and disturbance of the western US that began in the mid 19th century, the mountain snow cover of the Colorado River Basin has been subject to five-fold greater dust loading. Here we present the impacts of dust deposition onto alpine snow cover using a 7-year energy balance record at the alpine and subalpine towers in the Senator Beck Basin Study Area (SBBSA), San Juan Mountains in southwestern Colorado, USA. We assess the radiative and hydrologic impacts with a two-layer point snow energy balance snowmelt model that calculates snowmelt and predicts point runoff using measured inputs of energy exchanges and snow properties. By removing the radiative forcing due to dust, we can determine snowmelt under observed dusty and modeled clean conditions. Additionally, we model the relative response of melt rates to simulated increases in air temperature. Our modeling results indicate that the number of days that dust advances retreat of snow cover and cumulative radiative forcing are linearly related to total dust concentration. The greatest dust radiative impact occurred in 2009, when the highest observed end of year dust concentrations reduced visible albedo to less than 0.35 during the last three weeks of snowcover and snow cover duration was shortened by 50 days. This work also shows that dust radiative forcing has a markedly greater impact on snow cover duration than increases in temperature in terms of acceleration of snowmelt. We have completed the same analysis over a 2-year energy balance record at the Grand Mesa Study plot (GMSP) in west central Colorado, 150 km north of SBBSA. This new location allows us to assess site variability. For example, at SBBSA 2010 and 2011 were the second and third highest dust deposition years, respectively, but 2010 was a larger year with 3

  19. Relationships between radiation, clouds, and convection during DYNAMO

    Science.gov (United States)

    Ciesielski, Paul E.; Johnson, Richard H.; Jiang, Xianan; Zhang, Yunyan; Xie, Shaocheng

    2017-03-01

    The relationships between radiation, clouds, and convection on an intraseasonal time scale are examined with data taken during the Dynamics of the Madden-Julian Oscillation (MJO) field campaign. Specifically, column-net, as well as vertical profiles of radiative heating rates, computed over Gan Island in the central Indian Ocean (IO) are used along with an objective analysis of large-scale fields to examine three MJO events that occurred during the 3 month period (October to December 2011) over this region. Longwave (LW) and shortwave radiative heating rates exhibit tilted structures, reflecting radiative effects associated with the prevalence of shallow cumulus during the dry, suppressed MJO phase followed by increasing deep convection leading into the active phase. As the convection builds going into the MJO active phase, there are increasingly top-heavy anomalous radiative heating rates while the column-net radiative cooling rate progressively decreases. Temporal fluctuations in the cloud radiative forcing, being quite sensitive to changes in high cloudiness, are dominated by LW effects with an intraseasonal variation of 0.4-0.6 K/d. While both the water vapor and cloud fields are inextricably linked, it appears that the tilted radiative structures are more related to water vapor effects. The intraseasonal variation of column-net radiative heating enhances the convective signal in the mean by 20% with a minimum in this enhancement 10 days prior to peak MJO rainfall and maximum 7 days after. This suggests that as MJO convective envelope weakens over the central IO, cloud-radiative feedbacks help maintain the mature MJO as it moves eastward.

  20. LW-214, a newly synthesized flavonoid, induces intrinsic apoptosis pathway by down-regulating Trx-1 in MCF-7 human breast cells.

    Science.gov (United States)

    Pan, Di; Li, Wei; Miao, Hanchi; Yao, Jing; Li, Zhiyu; Wei, Libin; Zhao, Li; Guo, Qinglong

    2014-02-15

    In this study, the anticancer effect of LW-214, a newly synthesized flavonoid, against MCF-7 human breast cancer cells and the underlying mechanisms were investigated. LW-214 triggered the mitochondrial apoptotic pathway by increasing Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm) and caspase-9 activation, degradation of poly (ADP-ribose) polymerase (PARP), cytochrome c (Cyt c) release and apoptosis-inducing factor (AIF) transposition. Further research revealed that both the reactive oxygen species (ROS) generation and the apoptosis signal regulating kinase 1 (ASK1) activation by LW-214 were induced by down-regulating the thioredoxin-1 (Trx-1) expression. The ROS elevation and ASK1 activation induced a sustained phosphorylation of c-Jun N-terminal kinase (JNK), while SP600125, as known as JNK inhibitor, almost reversed LW-214-induced apoptosis in MCF-7 cells. Overexpression of Trx-1 in MCF-7 cells attenuated LW-214-mediated apoptosis as well as the JNK activation and reversed the expression of mitochondrial apoptosis-related protein. Accordingly, the in vivo study showed that LW-214 exhibited a potential antitumor effect in BALB/c species mice inoculated MCF-7 tumor with low systemic toxicity, and the mechanism was the same as in vitro study. Taken together, these findings indicated that LW-214 may down-regulated Trx-1 function, causing intracellular ROS generation and releasing the ASK1, and lead to JNK activation, which consequently induced the mitochondrial apoptosis in vitro and in vivo. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Effect of holed reflector on acoustic radiation force in noncontact ultrasonic dispensing of small droplets

    Science.gov (United States)

    Tanaka, Hiroki; Wada, Yuji; Mizuno, Yosuke; Nakamura, Kentaro

    2016-06-01

    We investigated the fundamental aspects of droplet dispensing, which is an important procedure in the noncontact ultrasonic manipulation of droplets in air. A holed reflector was used to dispense a droplet from a 27.4 kHz standing-wave acoustic field to a well. First, the relationship between the hole diameter of the reflector and the acoustic radiation force acting on a levitated droplet was clarified by calculating the acoustic impedance of the point just above the hole. When the hole diameter was half of (or equal to) the acoustic wavelength λ, the acoustic radiation force was ∼80% (or 50%) of that without a hole. The maximal diameters of droplets levitated above the holes through flat and half-cylindrical reflectors were then experimentally investigated. For instance, with the half-cylindrical reflector, the maximal diameter was 5.0 mm for a hole diameter of 6.0 mm, and droplets were levitatable up to a hole diameter of 12 mm (∼λ).

  2. Shipwreck rates reveal Caribbean tropical cyclone response to past radiative forcing.

    Science.gov (United States)

    Trouet, Valerie; Harley, Grant L; Domínguez-Delmás, Marta

    2016-03-22

    Assessing the impact of future climate change on North Atlantic tropical cyclone (TC) activity is of crucial societal importance, but the limited quantity and quality of observational records interferes with the skill of future TC projections. In particular, North Atlantic TC response to radiative forcing is poorly understood and creates the dominant source of uncertainty for twenty-first-century projections. Here, we study TC variability in the Caribbean during the Maunder Minimum (MM; 1645-1715 CE), a period defined by the most severe reduction in solar irradiance in documented history (1610-present). For this purpose, we combine a documentary time series of Spanish shipwrecks in the Caribbean (1495-1825 CE) with a tree-growth suppression chronology from the Florida Keys (1707-2009 CE). We find a 75% reduction in decadal-scale Caribbean TC activity during the MM, which suggests modulation of the influence of reduced solar irradiance by the cumulative effect of cool North Atlantic sea surface temperatures, El Niño-like conditions, and a negative phase of the North Atlantic Oscillation. Our results emphasize the need to enhance our understanding of the response of these oceanic and atmospheric circulation patterns to radiative forcing and climate change to improve the skill of future TC projections.

  3. Electronic excitations and their effect on the interionic forces in simulations of radiation damage in metals

    International Nuclear Information System (INIS)

    Race, C P; Mason, D R; Sutton, A P

    2009-01-01

    Using time-dependent tight-binding simulations of radiation damage cascades in a model metal we directly investigate the nature of the excitations of a system of quantum mechanical electrons in response to the motion of a set of classical ions. We furthermore investigate the effect of these excitations on the attractive electronic forces between the ions. We find that the electronic excitations are well described by a Fermi-Dirac distribution at some elevated temperature, even in the absence of the direct electron-electron interactions that would be required in order to thermalize a non-equilibrium distribution. We explain this result in terms of the spectrum of characteristic frequencies of the ionic motion. Decomposing the electronic force into four well-defined components within the basis of instantaneous electronic eigenstates, we find that the effect of accumulated excitations in weakening the interionic bonds is mostly (95%) accounted for by a thermal model for the electronic excitations. This result justifies the use of the simplifying assumption of a thermalized electron system in simulations of radiation damage with an electronic temperature dependence and in the development of temperature-dependent classical potentials.

  4. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments.

    Science.gov (United States)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R; Collins, Donald R; Molina, Mario J; Zhang, Renyi

    2016-04-19

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

  5. Electronic excitations and their effect on the interionic forces in simulations of radiation damage in metals.

    Science.gov (United States)

    Race, C P; Mason, D R; Sutton, A P

    2009-03-18

    Using time-dependent tight-binding simulations of radiation damage cascades in a model metal we directly investigate the nature of the excitations of a system of quantum mechanical electrons in response to the motion of a set of classical ions. We furthermore investigate the effect of these excitations on the attractive electronic forces between the ions. We find that the electronic excitations are well described by a Fermi-Dirac distribution at some elevated temperature, even in the absence of the direct electron-electron interactions that would be required in order to thermalize a non-equilibrium distribution. We explain this result in terms of the spectrum of characteristic frequencies of the ionic motion. Decomposing the electronic force into four well-defined components within the basis of instantaneous electronic eigenstates, we find that the effect of accumulated excitations in weakening the interionic bonds is mostly (95%) accounted for by a thermal model for the electronic excitations. This result justifies the use of the simplifying assumption of a thermalized electron system in simulations of radiation damage with an electronic temperature dependence and in the development of temperature-dependent classical potentials.

  6. Direct radiative forcing properties of atmospheric aerosols over semi-arid region, Anantapur in India.

    Science.gov (United States)

    Kalluri, Raja Obul Reddy; Gugamsetty, Balakrishnaiah; Kotalo, Rama Gopal; Nagireddy, Siva Kumar Reddy; Tandule, Chakradhar Rao; Thotli, Lokeswara Reddy; Rajuru Ramakrishna, Reddy; Surendranair, Suresh Babu

    2016-10-01

    This paper describes the aerosols optical, physical characteristics and the aerosol radiative forcing pertaining to semi-arid region, Anantapur for the period January 2013-December 2014. Collocated measurements of Aerosol Optical Depth (AOD) and Black Carbon mass concentration (BC) are carried out by using MICROTOPS II and Aethalometer and estimated the aerosol radiative forcing over this location. The mean values of AOD at 500nm are found to be 0.47±0.09, 0.34±0.08, 0.29±0.06 and 0.30±0.07 during summer, winter, monsoon and post-monsoon respectively. The Angstrom exponent (α380-1020) value is observed maximum in March (1.25±0.19) and which indicates the predominance of fine - mode aerosols and lowest in the month of July (0.33±0.14) and may be due to the dominance of coarse-mode aerosols. The diurnal variation of BC is exhibited two height peaks during morning 07:00-08:00 (IST) and evening 19:00-21:00 (IST) hours and one minima noticed during afternoon (13:00-16:00). The highest monthly mean BC concentration is observed in the month of January (3.4±1.2μgm(-3)) and the lowest in July (1.1±0.2μgm(-3)). The estimated Aerosol Direct Radiative Forcing (ADRF) in the atmosphere is found to be +36.8±1.7Wm(-2), +26.9±0.2Wm(-2), +18.0±0.6Wm(-2) and +18.5±3.1Wm(-2) during summer, winter, monsoon and post-monsoon seasons, respectively. Large difference between TOA and BOA forcing is observed during summer which indicate the large absorption of radiant energy (36.80Wm(-2)) which contributes more increase in atmospheric heating by ~1K/day. The BC contribution on an average is found to be 64% and is responsible for aerosol atmospheric heating. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Assessment of the impact of the greenhouse gas emission and sink scenarios in Finland on radiative forcing and greenhouse effect

    Energy Technology Data Exchange (ETDEWEB)

    Savolainen, I.; Sinisalo, J.; Pipatti, R. [Technical Research Centre of Finland, Espoo (Finland)

    1996-12-31

    The objective of this work is to study greenhouse gas emissions and sinks and their greenhouse impact as a function of time. The greenhouse impact is expressed in terms of global average radiative forcing, which measures the perturbation in the Earth`s radiation budget. Radiative forcing is calculated on the basis of the concentration changes of the greenhouse gases and the radiation absorption properties of the gases. It takes into account the relatively slow changes in the concentrations due to natural removal and transformation processes and also allows a comparison of the impact of various greenhouse gases and their possible control options as a function of time. In addition to the applications mentioned above, the anthropogenic greenhouse gas emission histories of Nordic countries have been estimated, and the radiative forcing caused by them has been calculated with REFUGE. The dynamic impact of aerosol emissions both from the global point of view and in the context of different energy sources (coal, oil and natural gas) have also been studied. In some instances the caused radiative forcing has been examined on a per capita basis. The radiative forcing calculations contain considerable uncertainty due to inaccurately known factors at several stages of the calculation (emission estimation, concentration calculation and radiative forcing calculation). The total uncertainty of the results is typically on the order of +- 40 %, when absolute values are used. If the results are used in a relative way, e.g. to compare the impacts of different scenarios, the final uncertainty is considerably less (typically + 10 %), due to correlations in almost all stages of the calculation process

  8. Assessment of the impact of the greenhouse gas emission and sink scenarios in Finland on radiative forcing and greenhouse effect

    Energy Technology Data Exchange (ETDEWEB)

    Savolainen, I; Sinisalo, J; Pipatti, R [Technical Research Centre of Finland, Espoo (Finland)

    1997-12-31

    The objective of this work is to study greenhouse gas emissions and sinks and their greenhouse impact as a function of time. The greenhouse impact is expressed in terms of global average radiative forcing, which measures the perturbation in the Earth`s radiation budget. Radiative forcing is calculated on the basis of the concentration changes of the greenhouse gases and the radiation absorption properties of the gases. It takes into account the relatively slow changes in the concentrations due to natural removal and transformation processes and also allows a comparison of the impact of various greenhouse gases and their possible control options as a function of time. In addition to the applications mentioned above, the anthropogenic greenhouse gas emission histories of Nordic countries have been estimated, and the radiative forcing caused by them has been calculated with REFUGE. The dynamic impact of aerosol emissions both from the global point of view and in the context of different energy sources (coal, oil and natural gas) have also been studied. In some instances the caused radiative forcing has been examined on a per capita basis. The radiative forcing calculations contain considerable uncertainty due to inaccurately known factors at several stages of the calculation (emission estimation, concentration calculation and radiative forcing calculation). The total uncertainty of the results is typically on the order of +- 40 %, when absolute values are used. If the results are used in a relative way, e.g. to compare the impacts of different scenarios, the final uncertainty is considerably less (typically + 10 %), due to correlations in almost all stages of the calculation process

  9. Occurrence of the Microcystins MC-LW and MC-LF in Dutch Surface Waters and Their Contribution to Total Microcystin Toxicity

    Directory of Open Access Journals (Sweden)

    Elisabeth J. Faassen

    2013-07-01

    Full Text Available Microcystins (MCs are the most frequently found cyanobacterial toxins in freshwater systems. Many MC variants have been identified and variants differ in their toxicity. Recent studies showed that the variants MC-LW and MC-LF might be more toxic than MC-LR, the variant that is most abundant and mostly used for risk assessments. As little is known about the presence of these two variants in The Netherlands, we determined their occurrence by analyzing 88 water samples and 10 scum samples for eight MC variants ((dm-7-MC-RR, MC-YR, (dm-7-MC-LR, MC-LY, MC-LW and MC-LF by liquid chromatography with tandem mass spectrometry detection. All analyzed MC variants were detected, and MC-LW and/or MC-LF were present in 32% of the MC containing water samples. When MC-LW and MC-LF were present, they contributed to nearly 10% of the total MC concentrations, but due to their suspected high toxicity, their average contribution to the total MC toxicity was estimated to be at least 45%. Given the frequent occurrence and possible high toxicity of MC-LW and MC-LF, it seems better to base health risk assessments on the toxicity contributions of different MC variants than on MC-LR concentrations alone.

  10. Dust, Elemental Carbon and Other Impurities on Central Asian Glaciers: Origin and Radiative Forcing

    Science.gov (United States)

    Schmale, J.; Flanner, M.; Kang, S.; Sprenger, M.; Zhang, Q.; Li, Y.; Guo, J.; Schwikowski, M.

    2015-12-01

    In Central Asia, more than 60 % of the population depends on water stored in glaciers and mountain snow. While temperature, precipitation and dynamic processes are key drivers of glacial change, deposition of light absorbing impurities such as mineral dust and black carbon can lead to accelerated melting through surface albedo reduction. Here, we discuss the origin of deposited mineral dust and black carbon and their impacts on albedo change and radiative forcing (RF). 218 snow samples were taken from 13 snow pits on 4 glaciers, Abramov (Pamir), Suek, Glacier No. 354 and Golubin (Tien Shan), representing deposition between summer 2012 and 2014. They were analyzed for elemental and organic carbon by a thermo-optical method, mineral dust by gravimetry, and iron by ICP-MS. Back trajectory ensembles were released every 6 hours with the Lagranto model for the covered period at all sites. Boundary layer "footprints" were calculated to estimate general source regions and combined with MODIS fire counts for potential fire contributions. Albedo reduction due to black carbon and mineral dust was calculated with the Snow-Ice-Aerosol-Radiative model (SNICAR), and surface spectral irradiances were derived from atmospheric radiative transfer calculations to determine the RF under clear-sky and all sky conditions using local radiation measurements. Dust contributions came from Central Asia, the Arabian Peninsula, the Sahara and partly the Taklimakan. Fire contributions were higher in 2014 and generally came from the West and North. We find that EC exerts roughly 3 times more RF than mineral dust in fresh and relatively fresh snow (~5 W/m2) and up to 6 times more in snow that experienced melting (> 10 W/m2) even though EC concentrations (average per snow pit from 90 to 700 ng/g) were up to two orders of magnitude lower than mineral dust (10 to 140 μg/g).

  11. Quantifying the climatological cloud-free direct radiative forcing of aerosol over the Red Sea

    KAUST Repository

    Brindley, Helen

    2015-04-01

    A combination of ground-based and satellite observations are used, in conjunction with column radiative transfer modelling, to assess the climatological aerosol loading and quantify its corresponding cloud-free direct radiative forcing (DRF) over the Red Sea. While there have been campaigns designed to probe aerosol-climate interactions over much of the world, relatively little attention has been paid to this region. Because of the remoteness of the area, satellite retrievals provide a crucial tool for assessing aerosol loading over the Sea. However, agreement between aerosol properties inferred from measurements from different instruments, and even in some cases from the same measurements using different retrieval algorithms can be poor, particularly in the case of mineral dust. Ground based measurements which can be used to evaluate retrievals are thus highly desirable. Here we take advantage of ship-based sun-photometer micro-tops observations gathered from a series of cruises which took place across the Red Sea during 2011 and 2013. To our knowledge these data represent the first set of detailed aerosol measurements from the Sea. They thus provide a unique opportunity to assess the performance of satellite retrieval algorithms in this region. Initially two aerosol optical depth (AOD) retrieval algorithms developed for the MODerate Resolution Imaging Spectroradiometer (MODIS) and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instruments are evaluated via comparison with the co-located cruise observations. These show excellent agreement, with correlations typically better than 0.9 and very small root-mean-square and bias differences. Calculations of radiative fluxes and DRF along one of the cruises using the observed aerosol and meteorological conditions also show good agreement with co-located estimates from the Geostationary Earth Radiation Budget (GERB) instrument if the aerosol asymmetry parameter is adjusted to account for the presence of large

  12. Effect of spectrally varying albedo of vegetation surfaces on shortwave radiation fluxes and aerosol direct radiative forcing

    Directory of Open Access Journals (Sweden)

    L. Zhu

    2012-12-01

    Full Text Available This study develops an algorithm for representing detailed spectral features of vegetation albedo based on Moderate Resolution Imaging Spectrometer (MODIS observations at 7 discrete channels, referred to as the MODIS Enhanced Vegetation Albedo (MEVA algorithm. The MEVA algorithm empirically fills spectral gaps around the vegetation red edge near 0.7 μm and vegetation water absorption features at 1.48 and 1.92 μm which cannot be adequately captured by the MODIS 7 channels. We then assess the effects of applying MEVA in comparison to four other traditional approaches to calculate solar fluxes and aerosol direct radiative forcing (DRF at the top of atmosphere (TOA based on the MODIS discrete reflectance bands. By comparing the DRF results obtained through the MEVA method with the results obtained through the other four traditional approaches, we show that filling the spectral gap of the MODIS measurements around 0.7 μm based on the general spectral behavior of healthy green vegetation leads to significant improvement in the instantaneous aerosol DRF at TOA (up to 3.02 W m−2 difference or 48% fraction of the aerosol DRF, −6.28 W m−2, calculated for high spectral resolution surface reflectance from 0.3 to 2.5 μm for deciduous vegetation surface. The corrections of the spectral gaps in the vegetation spectrum in the near infrared, again missed by the MODIS reflectances, also contributes to improving TOA DRF calculations but to a much lower extent (less than 0.27 W m−2, or about 4% of the instantaneous DRF.

    Compared to traditional approaches, MEVA also improves the accuracy of the outgoing solar flux between 0.3 to 2.5 μm at TOA by over 60 W m−2 (for aspen 3 surface and aerosol DRF by over 10 W m−2 (for dry grass. Specifically, for Amazon vegetation types, MEVA can improve the accuracy of daily averaged aerosol radiative forcing in the spectral range of 0.3 to 2.5 μm at

  13. Factors Affecting Aerosol Radiative Forcing from Both Production-based and Consumption-based View

    Science.gov (United States)

    Wang, J.; Lin, J.; Ni, R.

    2017-12-01

    Aerosol radiative forcing (RF) is determined by emissions and various chemical-transport-radiative processes in the atmosphere, a multi-factor problem whose individual contributors have not been well quantified. This problem becomes more complicated when taking into account the role of international trade, which means reallocated aerosol RF due to separation of regions producing goods and emissions and regions consuming those goods. Here we analyze major factors affecting RF of secondary inorganic aerosols (SIOAs, including sulfate, nitrate and ammonium), primary organic aerosol (POA) and black carbon (BC), extending the work of Lin et al. (2016, Nature Geoscience). We contrast five factors determining production-based (RFp, due to a region's production of goods) and consumption-based (RFc, due to a region's consumption) forcing by 11 major regions, including population size, per capita output, emission intensity (emission per output), chemical efficiency (mass per unit emission) and radiative efficiency (RF per unit mass). Comparing across the 11 regions, East Asia produces the strongest RFp and RFc of SIOA and BC and the second largest RFp and RFc of POA primarily due to its high emission intensity. Although Middle East and North Africa has low emissions, its RFp is strengthened by its largest chemical efficiency for POA and BC and second largest chemical efficiency for SIOA. However, RFp of South-East Asia and Pacific is greatly weakened by its lowest chemical efficiency. Economic trade means that net importers (Western Europe, North America and Pacific OECD) have higher RFc than RFp by 50-100%. And such forcing difference is mainly due to the high emission intensity of the exporters supplying these regions. For North America, SIOA's RFc is 50% stronger than RFp, for that emission intensity of SIOA is 5.2 times in East Asia and 2.5 times in Latin America and Caribbean compared with that in North America, and the chemical efficiency in the top four exporters are

  14. Relationship of scattering phase shifts to special radiation force conditions for spheres in axisymmetric wave-fields.

    Science.gov (United States)

    Marston, Philip L; Zhang, Likun

    2017-05-01

    When investigating the radiation forces on spheres in complicated wave-fields, the interpretation of analytical results can be simplified by retaining the s-function notation and associated phase shifts imported into acoustics from quantum scattering theory. For situations in which dissipation is negligible, as taken to be the case in the present investigation, there is an additional simplification in that partial-wave phase shifts become real numbers that vanish when the partial-wave index becomes large and when the wave-number-sphere-radius product vanishes. By restricting attention to monopole and dipole phase shifts, transitions in the axial radiation force for axisymmetric wave-fields are found to be related to wave-field parameters for traveling and standing Bessel wave-fields by considering the ratio of the phase shifts. For traveling waves, the special force conditions concern negative forces while for standing waves, the special force conditions concern vanishing radiation forces. An intermediate step involves considering the functional dependence on phase shifts. An appendix gives an approximation for zero-force plane standing wave conditions. Connections with early investigations of acoustic levitation are mentioned and some complications associated with viscosity are briefly noted.

  15. Continuous micro-feeding of fine cohesive powders actuated by pulse inertia force and acoustic radiation force in ultrasonic standing wave field.

    Science.gov (United States)

    Wang, Hongcheng; Wu, Liqun; Zhang, Ting; Chen, Rangrang; Zhang, Linan

    2018-07-10

    Stable continuous micro-feeding of fine cohesive powders has recently gained importance in many fields. However, it remains a great challenge in practice because of the powder aggregate caused by interparticle cohesive forces in small capillaries. This paper describes a novel method of feeding fine cohesive powder actuated by a pulse inertia force and acoustic radiation force simultaneously in an ultrasonic standing wave field using a tapered glass nozzle. Nozzles with different outlet diameters are fabricated using glass via a heating process. A pulse inertia force is excited to drive powder movement to the outlet section of the nozzle in a consolidated columnar rod mode. An acoustic radiation force is generated to suspend the particles and make the rod break into large quantities of small agglomerates which impact each other randomly. So the aggregation phenomenon in the fluidization of cohesive powders can be eliminated. The suspended powder is discharged continuously from the nozzle orifice owing to the self-gravities and collisions between the inner particles. The micro-feeding rates can be controlled accurately and the minimum values for RespitoseSV003 and Granulac230 are 0.4 mg/s and 0.5 mg/s respectively. The relative standard deviations of all data points are below 0.12, which is considerably smaller than those of existing vibration feeders with small capillaries. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Shortwave radiative forcing and efficiency of key aerosol types using AERONET data

    Directory of Open Access Journals (Sweden)

    O. E. García

    2012-06-01

    Full Text Available The shortwave radiative forcingF and the radiative forcing efficiency (ΔFeff of natural and anthropogenic aerosols have been analyzed using estimates of radiation both at the Top (TOA and at the Bottom Of Atmosphere (BOA modeled based on AERONET aerosol retrievals. Six main types of atmospheric aerosols have been compared (desert mineral dust, biomass burning, urban-industrial, continental background, oceanic and free troposphere in similar observational conditions (i.e., for solar zenith angles between 55° and 65° in order to compare the nearly same solar geometry. The instantaneous ΔF averages obtained vary from −122 ± 37 Wm−2 (aerosol optical depth, AOD, at 0.55 μm, 0.85 ± 0.45 at the BOA for the mixture of desert mineral dust and biomass burning aerosols in West Africa and −42 ± 22 Wm−2 (AOD = 0.9 ± 0.5 at the TOA for the pure mineral dust also in this region up to −6 ± 3 Wm−2 and −4 ± 2 Wm−2 (AOD = 0.03 ± 0.02 at the BOA and the TOA, respectively, for free troposphere conditions. This last result may be taken as reference on a global scale. Furthermore, we observe that the more absorbing aerosols are overall more efficient at the BOA in contrast to at the TOA, where they backscatter less solar energy into the space. The analysis of the radiative balance at the TOA shows that, together with the amount of aerosols and their absorptive capacity, it is essential to consider the surface albedo of the region on which they are. Thus, we document that in regions with high surface reflectivity (deserts and snow conditions atmospheric aerosols lead to a warming of the Earth-atmosphere system.

  17. Modelled radiative forcing of the direct aerosol effect with multi-observation evaluation

    Directory of Open Access Journals (Sweden)

    G. Myhre

    2009-02-01

    Full Text Available A high-resolution global aerosol model (Oslo CTM2 driven by meteorological data and allowing a comparison with a variety of aerosol observations is used to simulate radiative forcing (RF of the direct aerosol effect. The model simulates all main aerosol components, including several secondary components such as nitrate and secondary organic carbon. The model reproduces the main chemical composition and size features observed during large aerosol campaigns. Although the chemical composition compares best with ground-based measurement over land for modelled sulphate, no systematic differences are found for other compounds. The modelled aerosol optical depth (AOD is compared to remote sensed data from AERONET ground and MODIS and MISR satellite retrievals. To gain confidence in the aerosol modelling, we have tested its ability to reproduce daily variability in the aerosol content, and this is performing well in many regions; however, we also identified some locations where model improvements are needed. The annual mean regional pattern of AOD from the aerosol model is broadly similar to the AERONET and the satellite retrievals (mostly within 10–20%. We notice a significant improvement from MODIS Collection 4 to Collection 5 compared to AERONET data. Satellite derived estimates of aerosol radiative effect over ocean for clear sky conditions differs significantly on regional scales (almost up to a factor two, but also in the global mean. The Oslo CTM2 has an aerosol radiative effect close to the mean of the satellite derived estimates. We derive a radiative forcing (RF of the direct aerosol effect of −0.35 Wm−2 in our base case. Implementation of a simple approach to consider internal black carbon (BC mixture results in a total RF of −0.28 Wm−2. Our results highlight the importance of carbonaceous particles, producing stronger individual RF than considered in the recent IPCC estimate; however, net RF is less different

  18. Evidence of glucuronidation of the glycation product LW-1: tentative structure and implications for the long-term complications of diabetes.

    Science.gov (United States)

    Sell, David R; Nemet, Ina; Liang, Zhili; Monnier, Vincent M

    2018-04-01

    LW-1 is a collagen-linked blue fluorophore whose skin levels increase with age, diabetes and end-stage renal disease (ESRD), and correlate with the long-term progression of microvascular disease and indices of subclinical cardiovascular disease in type 1 diabetes. The chemical structure of LW-1 is still elusive, but earlier NMR analyses showed it has a lysine residue in an aromatic ring coupled to a sugar molecule reminiscent of advanced glycation end-products (AGEs). We hypothesized and demonstrate here that the unknown sugar is a N-linked glucuronic acid. LW-1 was extracted and highly purified from ~99 g insoluble skin collagen obtained at autopsy from patients with diabetes/ESRD using multiple rounds of proteolytic digestion and purification by liquid chromatography (LC). Advanced NMR techniques ( 1 H-NMR, 13 C-NMR, 1 H- 13 C HSQC, 1 H- 1 H TOCSY, 1 H- 13 C HMBC) together with LC-mass spectrometry (MS) revealed a loss of 176 amu (atomic mass unit) unequivocally point to the presence of a glucuronic acid moiety in LW-1. To confirm this data, LW-1 was incubated with β-glycosidases (glucosidase, galactosidase, glucuronidase) and products were analyzed by LC-MS. Only glucuronidase could cleave the sugar from the parent molecule. These results establish LW-1 as a glucuronide, now named glucuronidine, and for the first time raise the possible existence of a "glucuronidation pathway of diabetic complications". Future research is needed to rigorously probe this concept and elucidate the molecular origin and biological source of a circulating glucuronidine aglycone.

  19. Electron Tomography of Nanoparticle Clusters: Implications for Atmospheric Lifetimes and Radiative Forcing of Soot

    Science.gov (United States)

    vanPoppel, Laura H.; Friedrich, Heiner; Spinsby, Jacob; Chung, Serena H.; Seinfeld, John H.; Buseck, Peter R.

    2005-01-01

    Nanoparticles are ubiquitous in nature. Their large surface areas and consequent chemical reactivity typically result in their aggregation into clusters. Their chemical and physical properties depend on cluster shapes, which are commonly complex and unknown. This is the first application of electron tomography with a transmission electron microscope to quantitatively determine the three-dimensional (3D) shapes, volumes, and surface areas of nanoparticle clusters. We use soot (black carbon, BC) nanoparticles as an example because it is a major contributor to environmental degradation and global climate change. To the extent that our samples are representative, we find that quantitative measurements of soot surface areas and volumes derived from electron tomograms differ from geometrically derived values by, respectively, almost one and two orders of magnitude. Global sensitivity studies suggest that the global burden and direct radiative forcing of fractal BC are only about 60% of the value if it is assumed that BC has a spherical shape.

  20. Applications of acoustic radiation force impulse quantification in chronic kidney disease: A review

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liang [Dept. of Ultrasound, Chinese Academy of Medical Sciences and Peking Union Medical College Hospital, Beijing (China)

    2016-08-15

    Acoustic radiation force impulse (ARFI) imaging is an emerging technique with great promise in the field of elastography. Previous studies have validated ARFI quantification as a method of estimating fibrosis in chronic liver disease. Similarly, fibrosis is the principal process underlying the progression of chronic kidney disease, which is the major cause of renal failure. However, the quantification of tissue stiffness using ARFI imaging is more complex in the kidney than in the liver. Moreover, not all previous studies are comparable because they employed different procedures. Therefore, subsequent studies are warranted, both in animal models and in clinical patients, in order to better understand the histopathological mechanisms associated with renal elasticity and to further improve this imaging method by developing a standardized guidelines for its implementation.

  1. Applications of acoustic radiation force impulse quantification in chronic kidney disease: A review

    International Nuclear Information System (INIS)

    Wang, Liang

    2016-01-01

    Acoustic radiation force impulse (ARFI) imaging is an emerging technique with great promise in the field of elastography. Previous studies have validated ARFI quantification as a method of estimating fibrosis in chronic liver disease. Similarly, fibrosis is the principal process underlying the progression of chronic kidney disease, which is the major cause of renal failure. However, the quantification of tissue stiffness using ARFI imaging is more complex in the kidney than in the liver. Moreover, not all previous studies are comparable because they employed different procedures. Therefore, subsequent studies are warranted, both in animal models and in clinical patients, in order to better understand the histopathological mechanisms associated with renal elasticity and to further improve this imaging method by developing a standardized guidelines for its implementation

  2. State-Space Realization of the Wave-Radiation Force within FAST: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, T.; Sarmento, A.; Alves, M.; Jonkman, J.

    2013-06-01

    Several methods have been proposed in the literature to find a state-space model for the wave-radiation forces. In this paper, four methods were compared, two in the frequency domain and two in the time domain. The frequency-response function and the impulse response of the resulting state-space models were compared against the ones derived by the numerical code WAMIT. The implementation of the state-space module within the FAST offshore wind turbine computer-aided engineering (CAE) tool was verified, comparing the results against the previously implemented numerical convolution method. The results agreed between the two methods, with a significant reduction in required computational time when using the state-space module.

  3. Direct radiative forcing properties of atmospheric aerosols over semi-arid region, Anantapur in India

    Energy Technology Data Exchange (ETDEWEB)

    Kalluri, Raja Obul Reddy; Gugamsetty, Balakrishnaiah [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Kotalo, Rama Gopal, E-mail: krgverma@yahoo.com [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Nagireddy, Siva Kumar Reddy; Tandule, Chakradhar Rao; Thotli, Lokeswara Reddy [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Rajuru Ramakrishna, Reddy [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Srinivasa Ramanujan Institute of Technology, B.K. Samudram Mandal, Anantapur 515 701, Andhra Pradesh (India); Surendranair, Suresh Babu [Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum 695 022, Kerala (India)

    2016-10-01

    This paper describes the aerosols optical, physical characteristics and the aerosol radiative forcing pertaining to semi-arid region, Anantapur for the period January 2013-December 2014. Collocated measurements of Aerosol Optical Depth (AOD) and Black Carbon mass concentration (BC) are carried out by using MICROTOPS II and Aethalometer and estimated the aerosol radiative forcing over this location. The mean values of AOD at 500 nm are found to be 0.47 ± 0.09, 0.34 ± 0.08, 0.29 ± 0.06 and 0.30 ± 0.07 during summer, winter, monsoon and post-monsoon respectively. The Angstrom exponent (α{sub 380–1020}) value is observed maximum in March (1.25 ± 0.19) and which indicates the predominance of fine - mode aerosols and lowest in the month of July (0.33 ± 0.14) and may be due to the dominance of coarse-mode aerosols. The diurnal variation of BC is exhibited two height peaks during morning 07:00–08:00 (IST) and evening 19:00–21:00 (IST) hours and one minima noticed during afternoon (13:00–16:00). The highest monthly mean BC concentration is observed in the month of January (3.4 ± 1.2 μg m{sup −3}) and the lowest in July (1.1 ± 0.2 μg m{sup −3}). The estimated Aerosol Direct Radiative Forcing (ADRF) in the atmosphere is found to be + 36.8 ± 1.7 W m{sup −2}, + 26.9 ± 0.2 W m{sup −2}, + 18.0 ± 0.6 W m{sup −2} and + 18.5 ± 3.1 W m{sup −2} during summer, winter, monsoon and post-monsoon seasons, respectively. Large difference between TOA and BOA forcing is observed during summer which indicate the large absorption of radiant energy (36.80 W m{sup −2}) which contributes more increase in atmospheric heating by ~ 1 K/day. The BC contribution on an average is found to be 64% and is responsible for aerosol atmospheric heating. - Highlights: • The mean values of AOD{sub 500} are found to be high during summer whereas low in monsoon. • The highest values of BC are observed in January and the lowest in the month of July. • The annual mean

  4. Direct radiative forcing properties of atmospheric aerosols over semi-arid region, Anantapur in India

    International Nuclear Information System (INIS)

    Kalluri, Raja Obul Reddy; Gugamsetty, Balakrishnaiah; Kotalo, Rama Gopal; Nagireddy, Siva Kumar Reddy; Tandule, Chakradhar Rao; Thotli, Lokeswara Reddy; Rajuru Ramakrishna, Reddy; Surendranair, Suresh Babu

    2016-01-01

    This paper describes the aerosols optical, physical characteristics and the aerosol radiative forcing pertaining to semi-arid region, Anantapur for the period January 2013-December 2014. Collocated measurements of Aerosol Optical Depth (AOD) and Black Carbon mass concentration (BC) are carried out by using MICROTOPS II and Aethalometer and estimated the aerosol radiative forcing over this location. The mean values of AOD at 500 nm are found to be 0.47 ± 0.09, 0.34 ± 0.08, 0.29 ± 0.06 and 0.30 ± 0.07 during summer, winter, monsoon and post-monsoon respectively. The Angstrom exponent (α_3_8_0_–_1_0_2_0) value is observed maximum in March (1.25 ± 0.19) and which indicates the predominance of fine - mode aerosols and lowest in the month of July (0.33 ± 0.14) and may be due to the dominance of coarse-mode aerosols. The diurnal variation of BC is exhibited two height peaks during morning 07:00–08:00 (IST) and evening 19:00–21:00 (IST) hours and one minima noticed during afternoon (13:00–16:00). The highest monthly mean BC concentration is observed in the month of January (3.4 ± 1.2 μg m"−"3) and the lowest in July (1.1 ± 0.2 μg m"−"3). The estimated Aerosol Direct Radiative Forcing (ADRF) in the atmosphere is found to be + 36.8 ± 1.7 W m"−"2, + 26.9 ± 0.2 W m"−"2, + 18.0 ± 0.6 W m"−"2 and + 18.5 ± 3.1 W m"−"2 during summer, winter, monsoon and post-monsoon seasons, respectively. Large difference between TOA and BOA forcing is observed during summer which indicate the large absorption of radiant energy (36.80 W m"−"2) which contributes more increase in atmospheric heating by ~ 1 K/day. The BC contribution on an average is found to be 64% and is responsible for aerosol atmospheric heating. - Highlights: • The mean values of AOD_5_0_0 are found to be high during summer whereas low in monsoon. • The highest values of BC are observed in January and the lowest in the month of July. • The annual mean atmospheric forcing is found to be

  5. Regional Modeling of Dust Mass Balance and Radiative Forcing over East Asia using WRF-Chem

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Siyu; Zhao, Chun; Qian, Yun; Leung, Lai-Yung R.; Huang, J.; Huang, Zhongwei; Bi, Jianrong; Zhang, Wu; Shi, Jinsen; Yang, Lei; Li, Deshuai; Li, Jinxin

    2014-12-01

    The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and radiative forcing. A variety of measurements from in-stu and satellite observations have been used to evaluate simulation results. Generally, WRF-Chem reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions of East Asia. We investigate the dust lifecycle and the factors that control the seasonal and spatial variations of dust mass balance and radiative forcing over the seven sub-regions of East Asia, i.e. source regions, the Tibetan Plateau, Northern China, Southern China, the ocean outflow region, and Korea-Japan regions. Results show that, over the source regions, transport and dry deposition are the two dominant sinks. Transport contributes to ~30% of the dust sink over the source regions. Dust results in a surface cooling of up to -14 and -10 W m-2, atmospheric warming of up to 20 and 15 W m-2, and TOA cooling of -5 and -8 W m-2 over the two major dust source regions of East Asia, respectively. Over the Tibetan Plateau, transport is the dominant source with a peak in summer. Over identified outflow regions, maximum dust mass loading in spring is contributed by the transport. Dry and wet depositions are the comparably dominant sinks, but wet deposition is larger than dry deposition over the Korea-Japan region, particularly in spring (70% versus 30%). The WRF-Chem simulations can generally capture the measured features of dust aerosols and its radaitve properties and dust mass balance over East Asia, which provides confidence for use in further investigation of dust impact on climate over East Asia.

  6. Acoustic Radiation Force-Induced Creep-Recovery (ARFICR): A Noninvasive Method to Characterize Tissue Viscoelasticity.

    Science.gov (United States)

    Amador Carrascal, Carolina; Chen, Shigao; Urban, Matthew W; Greenleaf, James F

    2018-01-01

    Ultrasound shear wave elastography is a promising noninvasive, low cost, and clinically viable tool for liver fibrosis staging. Current shear wave imaging technologies on clinical ultrasound scanners ignore shear wave dispersion and use a single group velocity measured over the shear wave bandwidth to estimate tissue elasticity. The center frequency and bandwidth of shear waves induced by acoustic radiation force depend on the ultrasound push beam (push duration, -number, etc.) and the viscoelasticity of the medium, and therefore are different across scanners from different vendors. As a result, scanners from different vendors may give different tissue elasticity measurements within the same patient. Various methods have been proposed to evaluate shear wave dispersion to better estimate tissue viscoelasticity. A rheological model such as the Kelvin-Voigt model is typically fitted to the shear wave dispersion to solve for the elasticity and viscosity of tissue. However, these rheological models impose strong assumptions about frequency dependence of elasticity and viscosity. Here, we propose a new method called Acoustic Radiation Force Induced Creep-Recovery (ARFICR) capable of quantifying rheological model-independent measurements of elasticity and viscosity for more robust tissue health assessment. In ARFICR, the creep-recovery time signal at the focus of the push beam is used to calculate the relative elasticity and viscosity (scaled by an unknown constant) over a wide frequency range. Shear waves generated during the ARFICR measurement are also detected and used to calculate the shear wave velocity at its center frequency, which is then used to calibrate the relative elasticity and viscosity to absolute elasticity and viscosity. In this paper, finite-element method simulations and experiments in tissue mimicking phantoms are used to validate and characterize the extent of viscoelastic quantification of ARFICR. The results suggest that ARFICR can measure tissue

  7. Analytical and numerical calculations of optimum design frequency for focused ultrasound therapy and acoustic radiation force.

    Science.gov (United States)

    Ergün, A Sanlı

    2011-10-01

    Focused ultrasound therapy relies on acoustic power absorption by tissue. The stronger the absorption the higher the temperature increase is. However, strong acoustic absorption also means faster attenuation and limited penetration depth. Hence, there is a trade-off between heat generation efficacy and penetration depth. In this paper, we formulated the acoustic power absorption as a function of frequency and attenuation coefficient, and defined two figures of merit to measure the power absorption: spatial peak of the acoustic power absorption density, and the acoustic power absorbed within the focal area. Then, we derived "rule of thumb" expressions for the optimum frequencies that maximized these figures of merit given the target depth and homogeneous tissue type. We also formulated a method to calculate the optimum frequency for inhomogeneous tissue given the tissue composition for situations where the tissue structure can be assumed to be made of parallel layers of homogeneous tissue. We checked the validity of the rules using linear acoustic field simulations. For a one-dimensional array of 4cm acoustic aperture, and for a two-dimensional array of 4×4cm(2) acoustic aperture, we found that the power absorbed within the focal area is maximized at 0.86MHz, and 0.79MHz, respectively, when the target depth is 4cm in muscle tissue. The rules on the other hand predicted the optimum frequencies for acoustic power absorption as 0.9MHz and 0.86MHz, respectively for the 1D and 2D array case, which are within 6% and 9% of the field simulation results. Because radiation force generated by an acoustic wave in a lossy propagation medium is approximately proportional to the acoustic power absorption, these rules can be used to maximize acoustic radiation force generated in tissue as well. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Response of the Water Cycle of West Africa and Atlantic to Radiative Forcing by Saharan Dust

    Science.gov (United States)

    Lau, K. M.; Kim, Kyu-Myong; Sud, Yogesh C.; Walker, Gregory L.

    2010-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence in support of the "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feed back triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Easter Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean. region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while long wave has the opposite response. The elevated dust layer warms the air over Nest Africa and the eastern Atlantic. The condensation heating associated with the induced deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface energy fluxes, resulting in cooling of the Nest African land and the eastern Atlantic, and a warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.

  9. Spatial variability of the direct radiative forcing of biomass burning aerosols and the effects of land use change in Amazonia

    Directory of Open Access Journals (Sweden)

    E. T. Sena

    2013-02-01

    Full Text Available This paper addresses the Amazonian shortwave radiative budget over cloud-free conditions after considering three aspects of deforestation: (i the emission of aerosols from biomass burning due to forest fires; (ii changes in surface albedo after deforestation; and (iii modifications in the column water vapour amount over deforested areas. Simultaneous Clouds and the Earth's Radiant Energy System (CERES shortwave fluxes and aerosol optical depth (AOD retrievals from the Moderate Resolution Imaging SpectroRadiometer (MODIS were analysed during the peak of the biomass burning seasons (August and September from 2000 to 2009. A discrete-ordinate radiative transfer (DISORT code was used to extend instantaneous remote sensing radiative forcing assessments into 24-h averages.

    The mean direct radiative forcing of aerosols at the top of the atmosphere (TOA during the biomass burning season for the 10-yr studied period was −5.6 ± 1.7 W m−2. Furthermore, the spatial distribution of the direct radiative forcing of aerosols over Amazonia was obtained for the biomass burning season of each year. It was observed that for high AOD (larger than 1 at 550 nm the maximum daily direct aerosol radiative forcing at the TOA may be as high as −20 W m−2 locally. The surface reflectance plays a major role in the aerosol direct radiative effect. The study of the effects of biomass burning aerosols over different surface types shows that the direct radiative forcing is systematically more negative over forest than over savannah-like covered areas. Values of −15.7 ± 2.4 W m−2τ550 nm and −9.3 ± 1.7 W m−2τ550 nm were calculated for the mean daily aerosol forcing efficiencies over forest and savannah-like vegetation respectively. The overall mean annual land use change radiative forcing due to deforestation over the state of Rondônia, Brazil, was determined as −7.3 ± 0.9 W m

  10. Observational Characterization of the Downward Atmospheric Longwave Radiation at the Surface in the City of São Paulo

    NARCIS (Netherlands)

    Wilde Barbaro, E.; Oliveira, A.P.; Soares, J.; Codato, G.; Ferreira, M.J.; Mlakar, P.; Boznar, M.Z.; Escobedo, J.

    2010-01-01

    This work describes the seasonal and diurnal variations of downward longwave atmospheric irradiance (LW) at the surface in São Paulo, Brazil, using 5-min-averaged values of LW, air temperature, relative humidity, and solar radiation observed continuously and simultaneously from 1997 to 2006 on a

  11. Modelling the effects of the radiation reaction force on the interaction of thin foils with ultra-intense laser fields

    Science.gov (United States)

    Duff, M. J.; Capdessus, R.; Del Sorbo, D.; Ridgers, C. P.; King, M.; McKenna, P.

    2018-06-01

    The effects of the radiation reaction (RR) force on thin foils undergoing radiation pressure acceleration (RPA) are investigated. Using QED-particle-in-cell simulations, the influence of the RR force on the collective electron dynamics within the target can be examined. The magnitude of the RR force is found to be strongly dependent on the target thickness, leading to effects which can be observed on a macroscopic scale, such as changes to the distribution of the emitted radiation and the target dynamics. This suggests that such parameters may be controlled in experiments at multi-PW laser facilities. In addition, the effects of the RR force are characterized in terms of an average radiation emission angle. We present an analytical model which, for the first time, describes the effect of the RR force on the collective electron dynamics within the ‘light-sail’ regime of RPA. The predictions of this model can be tested in future experiments with ultra-high intensity lasers interacting with solid targets.

  12. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    Science.gov (United States)

    Talman, Richard; Malitsky, Nikolay; Stulle, Frank

    2009-01-01

    -21, MOCOS05, available at http://www.JACoW.org], a code with similar capabilities. For this comparison an appropriately new, 50 MeV, “standard chicane” is introduced. Unlike CSRTrack (which neglects vertical forces) the present simulation shows substantial growth of vertical emittance. But “turning off” vertical forces in the UAL code (to match the CSRTrack treatment) brings the two codes into excellent agreement. (iii) Results are also obtained for 5 GeV electrons passing through a previously introduced “standard chicane” [Coherent Synchrotron Radiation, CSR Workshop, Berlin 2002, http://www.desy.de/csr] [of the sort needed for linear colliders and free electron lasers (FEL’s) currently under design or construction]. Relatively little emittance growth is predicted for typical bunch parameters at such high electron energy. Results are obtained for both round beams and ribbon beams (like those actually needed in practice). Little or no excess emittance growth is found for ribbon bunches compared to round bunches of the same charge and bunch width. The UAL string space charge formulation (like TraFic4 and CSRTrack) avoids the regularization step (subtracting the free-space space charge force) which is required (to remove divergence) in some methods. Also, by avoiding the need to calculate a retarded-time, four-dimensional field history, the computation time needed for realistic bunch evolution calculations is modest. Some theories of bunch dilution, because they ascribe emittance growth entirely to CSR, break down at low energy. In the present treatment, as well as CSR, all free-space Coulomb and magnetic space charge forces (but not image forces), and also the centrifugal space charge force (CSCF) are included. Charge-dependent beam steering due to CSCF, as observed recently by Beutner et al. [B. Beutner , in Proceedings of FEL Conference, BESSY, Berlin, Germany, 2006, MOPPH009], is also investigated.

  13. Ultrasound power measurements of HITU transducer with a more stable radiation force balance

    Energy Technology Data Exchange (ETDEWEB)

    Karaboece, B; Sadiko' lu, E; Bilgic, E, E-mail: baki.karaboce@ume.tubitak.gov.t [Tuebitak Ulusal Metroloji Enstituesue (UME), P.K. 54 41470 Gebze-Kocaeli (Turkey)

    2011-02-01

    A new radiation force balance (RFB) system was established at Turkish National Metrology Institute (UME) Ultrasonics Laboratory for High intensity therapeutic ultrasound (HITU) power measurements. The new system is highly stable at high power levels up to 500 Watts. The measurement system consists of a Plexiglas cylindrical balance arm, target mounting scale disks, conical reflecting and absorbing targets, adjustment nuts, and a hanging wire. Both of the two sides of balance were mounted similar size and weight targets. The equilibrium of the balance arm can be adjusted with nuts on screws located at both sides of the balance arm. Transducer was mounted to bottom of water tank. Absorbers in the bottom and the near walls of the tank were used for reflecting target case. Ultrasound power was applied to one scale of the balance where the reflecting/absorbing target was mounted and corresponding force was measured on the other scale of balance where was connected to a balance with a thin wire while the thin rest standing on a support. Ultrasound power of two HITU transducers at frequencies 0.93 MHz, 1.1 MHz and 3.3 MHz were measured with conventional and new system, the values were compared and uncertainty components were assessed in this paper.

  14. Ultrasound power measurements of HITU transducer with a more stable radiation force balance

    International Nuclear Information System (INIS)

    Karaboece, B; Sadiko'lu, E; Bilgic, E

    2011-01-01

    A new radiation force balance (RFB) system was established at Turkish National Metrology Institute (UME) Ultrasonics Laboratory for High intensity therapeutic ultrasound (HITU) power measurements. The new system is highly stable at high power levels up to 500 Watts. The measurement system consists of a Plexiglas cylindrical balance arm, target mounting scale disks, conical reflecting and absorbing targets, adjustment nuts, and a hanging wire. Both of the two sides of balance were mounted similar size and weight targets. The equilibrium of the balance arm can be adjusted with nuts on screws located at both sides of the balance arm. Transducer was mounted to bottom of water tank. Absorbers in the bottom and the near walls of the tank were used for reflecting target case. Ultrasound power was applied to one scale of the balance where the reflecting/absorbing target was mounted and corresponding force was measured on the other scale of balance where was connected to a balance with a thin wire while the thin rest standing on a support. Ultrasound power of two HITU transducers at frequencies 0.93 MHz, 1.1 MHz and 3.3 MHz were measured with conventional and new system, the values were compared and uncertainty components were assessed in this paper.

  15. Scattering and absorption characteristics of aerosols at an urban megacity over IGB: Implications to radiative forcing

    Science.gov (United States)

    Srivastava, A. K.; Bisht, D. S.; Singh, Sachchidanand; Kishore, N.; Soni, V. K.; Singh, Siddhartha; Tiwari, S.

    2018-06-01

    Aerosol scattering and absorption characteristics were investigated at an urban megacity Delhi in the western Indo-Gangetic Basin (IGB) during the period from October 2011 to September 2012 using different in-situ measurements. The scattering coefficient (σsp at 550 nm) varied between 71 and 3014 Mm-1 (mean 710 ± 615 Mm-1) during the entire study period, which was about ten times higher than the absorption coefficient (σabs at 550 nm 67 ± 40 Mm-1). Seasonally, σsp and σabs were substantially higher during the winter/post-monsoon periods, which also gave rise to single scattering albedo (SSA) by 5%. The magnitude of SSA (at 550 nm) varied between 0.81 and 0.94 (mean: 0.89 ± 0.05). Further, the magnitude of scattering Ångström exponent (SAE) and back-scattering Ångström exponent (BAE) showed a wide range from -1.20 to 1.57 and -1.13 to 0.87, respectively which suggests large variability in aerosol sizes and emission sources. Relatively higher aerosol backscatter fraction (b at 550 nm) during the monsoon (0.25 ± 0.10) suggests more inhomogeneous scattering, associated with the coarser dust particles. However, lower value of b during winter (0.13 ± 0.02) is associated with more isotropic scattering due to dominance of smaller size particles. This is further confirmed with the estimated asymmetry parameter (AP at 550 nm), which exhibits opposite trend with b. The aerosol optical parameters were used in a radiative transfer model to estimate aerosol radiative forcing. A mean radiative forcing of -61 ± 22 W m-2 (ranging from -111 to -40 W m-2) was observed at the surface and 42 ± 24 W m-2 (ranging from 18 to 87 W m-2) into the atmosphere, which can give rise to the mean atmospheric heating rate of 1.18 K day-1.

  16. Interagency task force on the health effects of ionizing radiation: report of the work group on public information

    International Nuclear Information System (INIS)

    1979-06-01

    The health effects of ionizing radiation recently have been the focus of increased public concern. In response to this concern, in a May 9, 1978, memorandum the White House requested the Secretary of Health, Education, and Welfare to coordinate an interagency program that would, among other things, ensure public awareness and knowledge of the health effects of ionizing radiation. As a result, the Interagency Task Force on Ionizing Radiation was formed. The Information Work Group of the Task Force was asked to outline a public information program to meet the needs of the general public, the health and scientific community, workers, and other persons exposed to low levels of ionizing radiation in the past and at present or who may be exposed in the future. The Work Group is composed of 16 members, each representing an agency participating on the Interagency Task Force on Ionizing Radiation. The Work Group members used the draft Reports of the Science Work Group, the Radiation Exposure Reduction Work Group, the Care and Benefits Work Group, and the Privacy Work Group as a basis for developing the Information Report. In addition, the Information Work Group conducted a preliminary review of existing federal information programs. Meetings were held with representatives of environmental and trade groups, unions, and professional societies to help define the dimensions and priorities of a public information program

  17. A review of measurement-based assessments of the aerosol direct radiative effect and forcing

    Directory of Open Access Journals (Sweden)

    H. Yu

    2006-01-01

    Full Text Available Aerosols affect the Earth's energy budget directly by scattering and absorbing radiation and indirectly by acting as cloud condensation nuclei and, thereby, affecting cloud properties. However, large uncertainties exist in current estimates of aerosol forcing because of incomplete knowledge concerning the distribution and the physical and chemical properties of aerosols as well as aerosol-cloud interactions. In recent years, a great deal of effort has gone into improving measurements and datasets. It is thus feasible to shift the estimates of aerosol forcing from largely model-based to increasingly measurement-based. Our goal is to assess current observational capabilities and identify uncertainties in the aerosol direct forcing through comparisons of different methods with independent sources of uncertainties. Here we assess the aerosol optical depth (τ, direct radiative effect (DRE by natural and anthropogenic aerosols, and direct climate forcing (DCF by anthropogenic aerosols, focusing on satellite and ground-based measurements supplemented by global chemical transport model (CTM simulations. The multi-spectral MODIS measures global distributions of aerosol optical depth (τ on a daily scale, with a high accuracy of ±0.03±0.05τ over ocean. The annual average τ is about 0.14 over global ocean, of which about 21%±7% is contributed by human activities, as estimated by MODIS fine-mode fraction. The multi-angle MISR derives an annual average AOD of 0.23 over global land with an uncertainty of ~20% or ±0.05. These high-accuracy aerosol products and broadband flux measurements from CERES make it feasible to obtain observational constraints for the aerosol direct effect, especially over global the ocean. A number of measurement-based approaches estimate the clear-sky DRE (on solar radiation at the top-of-atmosphere (TOA to be about -5.5±0.2 Wm-2 (median ± standard error from various methods over the global ocean. Accounting for thin cirrus

  18. Climatic effects of 1950–2050 changes in US anthropogenic aerosols – Part 1: Aerosol trends and radiative forcing

    Directory of Open Access Journals (Sweden)

    D. G. Streets

    2012-04-01

    Full Text Available We calculate decadal aerosol direct and indirect (warm cloud radiative forcings from US anthropogenic sources over the 1950–2050 period. Past and future aerosol distributions are constructed using GEOS-Chem and historical emission inventories and future projections from the IPCC A1B scenario. Aerosol simulations are evaluated with observed spatial distributions and 1980–2010 trends of aerosol concentrations and wet deposition in the contiguous US. Direct and indirect radiative forcing is calculated using the GISS general circulation model and monthly mean aerosol distributions from GEOS-Chem. The radiative forcing from US anthropogenic aerosols is strongly localized over the eastern US. We find that its magnitude peaked in 1970–1990, with values over the eastern US (east of 100° W of −2.0 W m−2 for direct forcing including contributions from sulfate (−2.0 W m−2, nitrate (−0.2 W m−2, organic carbon (−0.2 W m−2, and black carbon (+0.4 W m−2. The uncertainties in radiative forcing due to aerosol radiative properties are estimated to be about 50%. The aerosol indirect effect is estimated to be of comparable magnitude to the direct forcing. We find that the magnitude of the forcing declined sharply from 1990 to 2010 (by 0.8 W m−2 direct and 1.0 W m−2 indirect, mainly reflecting decreases in SO2 emissions, and project that it will continue declining post-2010 but at a much slower rate since US SO2 emissions have already declined by almost 60% from their peak. This suggests that much of the warming effect of reducing US anthropogenic aerosol sources has already been realized. The small positive radiative forcing from US BC emissions (+0.3 W m−2 over the eastern US in 2010; 5% of the global forcing from anthropogenic BC emissions worldwide suggests that a US emission control strategy focused on BC would have only limited climate benefit.

  19. Climatic Effects of 1950-2050 Changes in US Anthropogenic Aerosols. Part 1; Aerosol Trends and Radiative Forcing

    Science.gov (United States)

    Leibensperger, E. M.; Mickley, L. J.; Jacob, D. J.; Chen, W.-T.; Seinfeld, J. H.; Nenes, A.; Adams, P. J.; Streets, D. G.; Kumar, N.; Rind, D.

    2012-01-01

    We calculate decadal aerosol direct and indirect (warm cloud) radiative forcings from US anthropogenic sources over the 1950-2050 period. Past and future aerosol distributions are constructed using GEOS-Chem and historical emission inventories and future projections from the IPCC A1B scenario. Aerosol simulations are evaluated with observed spatial distributions and 1980-2010 trends of aerosol concentrations and wet deposition in the contiguous US. Direct and indirect radiative forcing is calculated using the GISS general circulation model and monthly mean aerosol distributions from GEOS-Chem. The radiative forcing from US anthropogenic aerosols is strongly localized over the eastern US. We find that its magnitude peaked in 1970-1990, with values over the eastern US (east of 100 deg W) of -2.0Wm(exp-2 for direct forcing including contributions from sulfate (-2.0Wm-2), nitrate (-0.2Wm(exp-2), organic carbon (-0.2Wm(exp-2), and black carbon (+0.4Wm(exp-2). The uncertainties in radiative forcing due to aerosol radiative properties are estimated to be about 50 %. The aerosol indirect effect is estimated to be of comparable magnitude to the direct forcing. We find that the magnitude of the forcing declined sharply from 1990 to 2010 (by 0.8Wm(exp-2) direct and 1.0Wm(exp-2 indirect), mainly reflecting decreases in SO2 emissions, and project that it will continue declining post-2010 but at a much slower rate since US SO2 emissions have already declined by almost 60% from their peak. This suggests that much of the warming effect of reducing US anthropogenic aerosol sources has already been realized. The small positive radiative forcing from US BC emissions (+0.3Wm(exp-2 over the eastern US in 2010; 5% of the global forcing from anthropogenic BC emissions worldwide) suggests that a US emission control strategy focused on BC would have only limited climate benefit.

  20. Idiopathic paraproteinemia. II. Transplantation of the paraprotein- producing clone from old to young C57BL/KaLwRij mice

    NARCIS (Netherlands)

    Radl, J.; Glopper, E.de; Schuit, H.R.E.; Zurcher, C.

    1979-01-01

    Transplantation experiments in the C57BL/KaLwRij mouse model of idiopathic paraproteinemia (IP) showed that an IP-producing clone can be further propagated in young, lethally irradiated mice and also equally as well in nonirradiated recipients by a bone marrow and/or spleen cell transfer. The

  1. Idiopathic paraproteinemia. III. Increased frequency of paraproteinemia in thymectomized aging C57BL/KaLwRij and CBA/BrARij mice

    NARCIS (Netherlands)

    Radl, J.; Glopper, E. de; Berg, P. van den; Zwieten, M.J. van

    1980-01-01

    The influence of thymectomy on the appearance of idiopathic paraproteinemia (IP) during aging was investigated in mice of the C57BL/KaLwRij and CBA/BrARij strains, which under normal conditions develop IP in high and low frequency, respectively. Compared with sham-thymectomized mice, C57BL mice

  2. Air Pollution Radiative Forcing From Specific Emissions Sectors at 2030: Prototype for a New IPCC Bar Chart

    Science.gov (United States)

    Unger, N.; Shindell, D. T.; Koch, D. M.

    2007-05-01

    Reduction of short-lived air pollutants provides a way to mitigate global warming in the short-term with ancillary benefits to human health. However, the radiative forcings of short-lived air pollutants depend on the location and source type of the precursor emissions. We apply the GISS atmospheric composition-climate model to quantify near future (2030 A1B) ozone (O3) and sulfate global mean direct radiative forcing impacts from 6 emissions sectors from 7 geographic regions. At 2030 the net forcings for the emissions sectors (including O3, sulfate, black and organic carbon forcings) are (in mW/m2): transportation = +106; biomass burning = +69; domestic = +38; power = -158; industry = -124. Hence the transportation sector is the most attractive target to counter global warming via reduction of short-lived air pollutants. Substantial transportation sector O3 forcings come from all regions (5-12 mW/m2). Central and Southern Africa and South America contribute the largest biomass burning O3 forcings (11-15 mW/m2). Domestic biofuel emissions from East Asia, South Asia and Central and South Africa and power and industry emissions from East Asia also contribute substantial O3 forcings (7-15mW/m2). The global mean sulfate forcings are dominated by the power and industry sectors with largest contributions from East Asia, South Asia and North Africa and Middle East (-30 to -50 mW/m2). Linear relationships exist between global mean radiative forcing by O3 and biomass burning and domestic biofuel CO precursor emissions independent of the region of origin with sensitivity of 0.02mW/m2/TgCO. Similarly, linear relationships are available for global mean radiative forcing by sulfate and SO2 precursor emissions that depend upon region but are independent of the emissions sector with sensitivities ranging from -3 to -12mW/m2/TgS. Such emissions to forcing diagnostics will assist development of climate-motivated policy for O3 and sulfate.

  3. Impact of uncertainties in inorganic chemical rate constants on tropospheric composition and ozone radiative forcing

    Directory of Open Access Journals (Sweden)

    B. Newsome

    2017-12-01

    regions such as the tropics, poles and upper troposphere are most uncertain. This chemical uncertainty is sufficiently large to suggest that rate constant uncertainty should be considered alongside other processes when model results disagree with measurement. Calculations for the pre-industrial simulation allow a tropospheric ozone radiative forcing to be calculated of 0.412 ± 0.062 W m−2. This uncertainty (13 % is comparable to the inter-model spread in ozone radiative forcing found in previous model–model intercomparison studies where the rate constants used in the models are all identical or very similar. Thus, the uncertainty of tropospheric ozone radiative forcing should expanded to include this additional source of uncertainty. These rate constant uncertainties are significant and suggest that refinement of supposedly well-known chemical rate constants should be considered alongside other improvements to enhance our understanding of atmospheric processes.

  4. Aerosol radiative forcing during African desert dust events (2005–2010 over Southeastern Spain

    Directory of Open Access Journals (Sweden)

    A. Valenzuela

    2012-11-01

    Full Text Available The daily (24 h averages of the aerosol radiative forcing (ARF at the surface and the top of the atmosphere (TOA were calculated during desert dust events over Granada (southeastern Spain from 2005 to 2010. A radiative transfer model (SBDART was utilized to simulate the solar irradiance values (0.31–2.8 μm at the surface and TOA, using as input aerosol properties retrieved from CIMEL sun photometer measurements via an inversion methodology that uses the sky radiance measurements in principal plane configuration and a spheroid particle shape approximation. This inversion methodology was checked by means of simulated data from aerosol models, and the derived aerosol properties were satisfactorily compared against well-known AERONET products. Good agreement was found over a common spectral interval (0.2–4.0 μm between the simulated SBDART global irradiances at surface and those provided by AERONET. In addition, simulated SBDART solar global irradiances at the surface have been successfully validated against CM-11 pyranometer measurements. The comparison indicates that the radiative transfer model slightly overestimates (mean bias of 3% the experimental solar global irradiance. These results show that the aerosol optical properties used to estimate ARF represent appropriately the aerosol properties observed during desert dust outbreak over the study area. The ARF mean monthly values computed during desert dust events ranged from −13 ± 8 W m−2 to −34 ± 15 W m−2 at surface, from −4 ± 3 W m−2 to −13 ± 7 W m−2 at TOA and from +6 ± 4 to +21 ± 12 W m−2 in the atmosphere. We have checked if the differences found in aerosol optical properties among desert dust sectors translate to differences in ARF. The mean ARF at surface (TOA were −20 ± 12 (−5 ± 5 W m−2, −21 ± 9 (−7 ± 5 W m−2 and −18 ± 9 (−6 ± 5 W m−2 for sector A

  5. Carbonaceous aerosols and pollutants over Delhi urban environment: Temporal evolution, source apportionment and radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Bisht, D.S. [Indian Institute of Tropical Meteorology, New Delhi (India); Dumka, U.C., E-mail: dumka@aries.res.in [Aryabhatta Research Institute of Observational Sciences, Nainital (India); Kaskaoutis, D.G. [School of Natural Sciences, Shiv Nadar University, Tehsil Dadri (India); Pipal, A.S. [Department of Chemistry, Savitribai Phule Pune University, Pune (India); Srivastava, A.K. [Indian Institute of Tropical Meteorology, New Delhi (India); Soni, V.K.; Attri, S.D.; Sateesh, M. [India Meteorology Department, Lodhi Road, New Delhi (India); Tiwari, S. [Indian Institute of Tropical Meteorology, New Delhi (India)

    2015-07-15

    Particulate matter (PM{sub 2.5}) samples were collected over Delhi, India during January to December 2012 and analysed for carbonaceous aerosols and inorganic ions (SO{sub 4}{sup 2−} and NO{sub 3}{sup −}) in order to examine variations in atmospheric chemistry, combustion sources and influence of long-range transport. The PM{sub 2.5} samples are measured (offline) via medium volume air samplers and analysed gravimetrically for carbonaceous (organic carbon, OC; elemental carbon, EC) aerosols and inorganic ions (SO{sub 4}{sup 2−} and NO{sub 3}{sup −}). Furthermore, continuous (online) measurements of PM{sub 2.5} (via Beta-attenuation analyser), black carbon (BC) mass concentration (via Magee scientific Aethalometer) and carbon monoxide (via CO-analyser) are carried out. PM{sub 2.5} (online) range from 18.2 to 500.6 μg m{sup −3} (annual mean of 124.6 ± 87.9 μg m{sup −3}) exhibiting higher night-time (129.4 μg m{sup −3}) than daytime (103.8 μg m{sup −3}) concentrations. The online concentrations are 38% and 28% lower than the offline during night and day, respectively. In general, larger night-time concentrations are found for the BC, OC, NO{sub 3}{sup −}and SO{sub 4}{sup 2−}, which are seasonally dependent with larger differences during late post-monsoon and winter. The high correlation (R{sup 2} = 0.74) between OC and EC along with the OC/EC of 7.09 (day time) and 4.55 (night-time), suggest significant influence of biomass-burning emissions (burning of wood and agricultural waste) as well as secondary organic aerosol formation during daytime. Concentrated weighted trajectory (CWT) analysis reveals that the potential sources for the carbonaceous aerosols and pollutants are local emissions within the urban environment and transported smoke from agricultural burning in northwest India during post-monsoon. BC radiative forcing estimates result in very high atmospheric heating rates (~ 1.8–2.0 K day{sup −1}) due to agricultural burning effects

  6. Carbonaceous aerosols and pollutants over Delhi urban environment: Temporal evolution, source apportionment and radiative forcing

    International Nuclear Information System (INIS)

    Bisht, D.S.; Dumka, U.C.; Kaskaoutis, D.G.; Pipal, A.S.; Srivastava, A.K.; Soni, V.K.; Attri, S.D.; Sateesh, M.; Tiwari, S.

    2015-01-01

    Particulate matter (PM 2.5 ) samples were collected over Delhi, India during January to December 2012 and analysed for carbonaceous aerosols and inorganic ions (SO 4 2− and NO 3 − ) in order to examine variations in atmospheric chemistry, combustion sources and influence of long-range transport. The PM 2.5 samples are measured (offline) via medium volume air samplers and analysed gravimetrically for carbonaceous (organic carbon, OC; elemental carbon, EC) aerosols and inorganic ions (SO 4 2− and NO 3 − ). Furthermore, continuous (online) measurements of PM 2.5 (via Beta-attenuation analyser), black carbon (BC) mass concentration (via Magee scientific Aethalometer) and carbon monoxide (via CO-analyser) are carried out. PM 2.5 (online) range from 18.2 to 500.6 μg m −3 (annual mean of 124.6 ± 87.9 μg m −3 ) exhibiting higher night-time (129.4 μg m −3 ) than daytime (103.8 μg m −3 ) concentrations. The online concentrations are 38% and 28% lower than the offline during night and day, respectively. In general, larger night-time concentrations are found for the BC, OC, NO 3 − and SO 4 2− , which are seasonally dependent with larger differences during late post-monsoon and winter. The high correlation (R 2 = 0.74) between OC and EC along with the OC/EC of 7.09 (day time) and 4.55 (night-time), suggest significant influence of biomass-burning emissions (burning of wood and agricultural waste) as well as secondary organic aerosol formation during daytime. Concentrated weighted trajectory (CWT) analysis reveals that the potential sources for the carbonaceous aerosols and pollutants are local emissions within the urban environment and transported smoke from agricultural burning in northwest India during post-monsoon. BC radiative forcing estimates result in very high atmospheric heating rates (~ 1.8–2.0 K day −1 ) due to agricultural burning effects during the 2012 post-monsoon season. - Highlights: • Very high PM 2.5 (> 200 µg m −3 ) levels

  7. Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

    Directory of Open Access Journals (Sweden)

    C. R. MacIntosh

    2015-04-01

    Full Text Available Multi-model ensembles are frequently used to assess understanding of the response of ozone and methane lifetime to changes in emissions of ozone precursors such as NOx, VOCs (volatile organic compounds and CO. When these ozone changes are used to calculate radiative forcing (RF (and climate metrics such as the global warming potential (GWP and global temperature-change potential (GTP there is a methodological choice, determined partly by the available computing resources, as to whether the mean ozone (and methane concentration changes are input to the radiation code, or whether each model's ozone and methane changes are used as input, with the average RF computed from the individual model RFs. We use data from the Task Force on Hemispheric Transport of Air Pollution source–receptor global chemical transport model ensemble to assess the impact of this choice for emission changes in four regions (East Asia, Europe, North America and South Asia. We conclude that using the multi-model mean ozone and methane responses is accurate for calculating the mean RF, with differences up to 0.6% for CO, 0.7% for VOCs and 2% for NOx. Differences of up to 60% for NOx 7% for VOCs and 3% for CO are introduced into the 20 year GWP. The differences for the 20 year GTP are smaller than for the GWP for NOx, and similar for the other species. However, estimates of the standard deviation calculated from the ensemble-mean input fields (where the standard deviation at each point on the model grid is added to or subtracted from the mean field are almost always substantially larger in RF, GWP and GTP metrics than the true standard deviation, and can be larger than the model range for short-lived ozone RF, and for the 20 and 100 year GWP and 100 year GTP. The order of averaging has most impact on the metrics for NOx, as the net values for these quantities is the residual of the sum of terms of opposing signs. For example, the standard deviation for the 20 year GWP is 2–3

  8. The Use of Acoustic Radiation Force Decorrelation-Weighted Pulse Inversion for Enhanced Ultrasound Contrast Imaging.

    Science.gov (United States)

    Herbst, Elizabeth B; Unnikrishnan, Sunil; Wang, Shiying; Klibanov, Alexander L; Hossack, John A; Mauldin, Frank William

    2017-02-01

    The use of ultrasound imaging for cancer diagnosis and screening can be enhanced with the use of molecularly targeted microbubbles. Nonlinear imaging strategies such as pulse inversion (PI) and "contrast pulse sequences" (CPS) can be used to differentiate microbubble signal, but often fail to suppress highly echogenic tissue interfaces. This failure results in false-positive detection and potential misdiagnosis. In this study, a novel acoustic radiation force (ARF)-based approach was developed for superior microbubble signal detection. The feasibility of this technique, termed ARF decorrelation-weighted PI (ADW-PI), was demonstrated in vivo using a subcutaneous mouse tumor model. Tumors were implanted in the hindlimb of C57BL/6 mice by subcutaneous injection of MC38 cells. Lipid-shelled microbubbles were conjugated to anti-VEGFR2 antibody and administered via bolus injection. An image sequence using ARF pulses to generate microbubble motion was combined with PI imaging on a Verasonics Vantage programmable scanner. ADW-PI images were generated by combining PI images with interframe signal decorrelation data. For comparison, CPS images of the same mouse tumor were acquired using a Siemens Sequoia clinical scanner. Microbubble-bound regions in the tumor interior exhibited significantly higher signal decorrelation than static tissue (n = 9, P < 0.001). The application of ARF significantly increased microbubble signal decorrelation (n = 9, P < 0.01). Using these decorrelation measurements, ADW-PI imaging demonstrated significantly improved microbubble contrast-to-tissue ratio when compared with corresponding CPS or PI images (n = 9, P < 0.001). Contrast-to-tissue ratio improved with ADW-PI by approximately 3 dB compared with PI images and 2 dB compared with CPS images. Acoustic radiation force can be used to generate adherent microbubble signal decorrelation without microbubble bursting. When combined with PI, measurements of the resulting microbubble signal

  9. Contributions of projected land use to global radiative forcing ascribed to local sources

    Science.gov (United States)

    Ward, D. S.; Mahowald, N. M.; Kloster, S.

    2013-12-01

    With global demand for food expected to dramatically increase and put additional pressures on natural lands, there is a need to understand the environmental impacts of land use and land cover change (LULCC). Previous studies have shown that the magnitude and even the sign of the radiative forcing (RF) of biogeophysical effects from LULCC depends on the latitude and forest ecology of the disturbed region. Here we ascribe the contributions to the global RF by land-use related anthropogenic activities to their local sources, organized on a grid of 1.9 degrees latitude by 2.5 degrees longitude. We use RF estimates for the year 2100, using five future LULCC projections, computed from simulations with the National Center for Atmospheric Research Community Land Model and Community Atmosphere Models and additional offline analyses. Our definition of the LULCC RF includes changes to terrestrial carbon storage, methane and nitrous oxide emissions, atmospheric chemistry, aerosol emissions, and surface albedo. We ascribe the RF to gridded locations based on LULCC-related emissions of relevant trace gases and aerosols, including emissions from fires. We find that the largest contributions to the global RF in year 2100 from LULCC originate in the tropics for all future scenarios. In fact, LULCC is the largest tropical source of anthropogenic RF. The LULCC RF in the tropics is dominated by emissions of CO2 from deforestation and methane emissions from livestock and soils. Land surface albedo change is rarely the dominant forcing agent in any of the future LULCC projections, at any location. By combining the five future scenarios we find that deforested area at a specific tropical location can be used to predict the contribution to global RF from LULCC at that location (the relationship does not hold as well in the extratropics). This information could support global efforts like REDD (Reducing Emissions from Deforestation and Forest Degradation), that aim to reduce greenhouse gas

  10. Impact of ice particle shape on short-wave radiative forcing: A case study for an arctic ice cloud

    International Nuclear Information System (INIS)

    Kahnert, Michael; Sandvik, Anne Dagrun; Biryulina, Marina; Stamnes, Jakob J.; Stamnes, Knut

    2008-01-01

    We used four different non-spherical particle models to compute optical properties of an arctic ice cloud and to simulate corresponding cloud radiative forcings and fluxes. One important finding is that differences in cloud forcing, downward flux at the surface, and absorbed flux in the atmosphere resulting from the use of the four different ice cloud particle models are comparable to differences in these quantities resulting from changing the surface albedo from 0.4 to 0.8, or by varying the ice water content (IWC) by a factor of 2. These findings show that the use of a suitable non-spherical ice cloud particle model is very important for a realistic assessment of the radiative impact of arctic ice clouds. The differences in radiative broadband fluxes predicted by the four different particle models were found to be caused mainly by differences in the optical depth and the asymmetry parameter. These two parameters were found to have nearly the same impact on the predicted cloud forcing. Computations were performed first by assuming a given vertical profile of the particle number density, then by assuming a given profile of the IWC. In both cases, the differences between the cloud radiative forcings computed with the four different non-spherical particle models were found to be of comparable magnitude. This finding shows that precise knowledge of ice particle number density or particle mass is not sufficient for accurate prediction of ice cloud radiative forcing. It is equally important to employ a non-spherical shape model that accurately reproduces the ice particle's dimension-to-volume ratio and its asymmetry parameter. The hexagonal column/plate model with air-bubble inclusions seems to offer the highest degree of flexibility

  11. A Study of Direct and Cloud-Mediated Radiative Forcing of Climate Due to Aerosols

    Science.gov (United States)

    Yu, Shao-Cai

    1999-01-01

    The Intergovernmental Panel on Climate Change (IPCC) has reported that in the southeastern US and eastern China, the general greenhouse warming due to anthropogenic gaseous emissions is dominated by the cooling effect of anthropogenic aerosols. To verify this model prediction in eastern China and southeastern US, we analyzed regional patterns of climate changes at 72 stations in eastern China during 1951- 94 (44 years), and at 52 stations in the southeastern US during 1949-94 (46 years) to detect the fingerprint of aerosol radiative forcing. It was found that the mean rates of change of annual mean daily, maximum, minimum temperatures and diurnal temperature range (DTR) in eastern China were 0.8, -0.2, 1.8, and -2.0 C/100 years respectively, while the mean rates of change of annual mean daily, maximum, minimum temperatures and DTR in the southeastern US were -0.2, -0.6, 0.2, and -0.8 C/100 years, respectively. This indicates that the high rate of increase in annual mean minimum temperature in eastern China results in a slightly warming trend of daily temperature, while the high rate of decrease in annual mean maximum temperature and low rate of increase in annual mean minimum temperature lead to the cooling trend of daily temperature in the southeastern US. We found that the warming from the longwave forcing due to both greenhouse gases and aerosols was completely counteracted by the shortwave aerosol forcing in the southeastern US in the past 46 years. A slightly overall warming trend in eastern China is evident; winters have become milder. This finding is explained by hypothesizing that increasing energy usage during the past 44 years has resulted in more coal and biomass burning, thus increasing the emission of absorbing soot and organic aerosols in eastern China. Such emissions, in addition to well-known Asia dust and greenhouse gases, may be responsible for the winter warming trend in eastern China that we have reported here. The sensitivity of aerosol

  12. Assessment of placental stiffness using acoustic radiation force impulse elastography in pregnant women with fetal anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Alan, Bircan; Goya, Cemil; Tunc, Senem; Teke, Memik; Hattapoglu, Salih [Dicle University Medical Faculty, Diyarbakir (Turkmenistan)

    2016-04-15

    We aimed to evaluate placental stiffness measured by acoustic radiation force impulse (ARFI) elastography in pregnant women in the second trimester with a normal fetus versus those with structural anomalies and non-structural findings. Forty pregnant women carrying a fetus with structural anomalies diagnosed sonographically at 18-28 weeks of gestation comprised the study group. The control group consisted of 34 healthy pregnant women with a sonographically normal fetus at a similar gestational age. Placental shear wave velocity (SWV) was measured by ARFI elastography and compared between the two groups. Structural anomalies and non-structural findings were scored based on sonographic markers. Placental stiffness measurements were compared among fetus anomaly categories. Doppler parameters of umbilical and uterine arteries were compared with placental SWV measurements. All placental SWV measurements, including minimum SWV, maximum SWV, and mean SWV were significantly higher in the study group than the control group ([0.86 ± 0.2, 0.74 ± 0.1; p < 0.001], [1.89 ± 0.7, 1.59 ± 0.5; p = 0.04], and [1.26 ± 0.4, 1.09 ± 0.2; p = 0.01]), respectively. Placental stiffness evaluated by ARFI elastography during the second trimester in pregnant women with fetuses with congenital structural anomalies is higher than that of pregnant women with normal fetuses.

  13. A modeling study of effective radiative forcing and climate response due to increased methane concentration

    Directory of Open Access Journals (Sweden)

    Bing Xie

    2016-12-01

    Full Text Available An atmospheric general circulation model BCC_AGCM2.0 and observation data from ARIS were used to calculate the effective radiative forcing (ERF due to increased methane concentration since pre-industrial times and its impacts on climate. The ERF of methane from 1750 to 2011 was 0.46 W m−2 by taking it as a well-mixed greenhouse gas, and the inhomogeneity of methane increased its ERF by about 0.02 W m−2. The change of methane concentration since pre-industrial led to an increase of 0.31 °C in global mean surface air temperature and 0.02 mm d−1 in global mean precipitation. The warming was prominent over the middle and high latitudes of the Northern Hemisphere (with a maximum increase exceeding 1.4 °C. The precipitation notably increased (maximum increase of 1.8 mm d−1 over the ocean between 10°N and 20°N and significantly decreased (maximum decrease >–0.6 mm d−1 between 10°S and 10°N. These changes caused a northward movement of precipitation cell in the Intertropical Convergence Zone (ITCZ. Cloud cover significantly increased (by approximately 4% in the high latitudes in both hemispheres, and sharply decreased (by approximately 3% in tropical areas.

  14. Artificial ion tracks in volcanic dark mica simulating natural radiation damage: A scanning force microscopy study

    International Nuclear Information System (INIS)

    Lang, M.; Glasmacher, U.A.; Moine, B.; Mueller, C.; Neumann, R.; Wagner, G.A.

    2002-01-01

    A new dating technique uses alpha-recoil tracks (ART), formed by the natural α-decay of U, Th and their daughter products, to determine the formation age of Quaternary volcanic rocks ( 6 a). Visualization of etched ART by scanning force microscopy (SFM) enables to access track densities beyond 10 8 cm -2 and thus extend the new ART-dating technique to an age range >10 6 a. In order to simulate natural radiation damage, samples of phlogopite, originating from Quaternary and Tertiary volcanic rocks of the Eifel (Germany) and Kerguelen Islands (Indian Ocean) were irradiated with U, Ni (11.4 MeV/u), Xe, Cr, Ne (1.4 MeV/u) and Bi (200 keV) ions. After irradiation and etching with HF at various etching times, phlogopite surfaces were visualized by SFM. Hexagonal etch pits are typical of U, Xe and Cr ion tracks, but the etch pits of Ni, Ne and Bi ion tracks are triangular. Surfaces irradiated with U, Xe, Cr and Ni ions do not show any significant difference between etch pit density and irradiation fluence, whereas the Ne-irradiated surface show ∼14 times less etch pit density. The etching rate v H (parallel to cleavage) depends on the chemical composition of the phlogopite. The etching rate v T ' (along the track) increases with energy loss

  15. In vivo visualization of abdominal malignancies with acoustic radiation force elastography

    International Nuclear Information System (INIS)

    Fahey, B J; Nelson, R C; Bradway, D P; Hsu, S J; Dumont, D M; Trahey, G E

    2008-01-01

    The utility of acoustic radiation force impulse (ARFI) imaging for real-time visualization of abdominal malignancies was investigated. Nine patients presenting with suspicious masses in the liver (n = 7) or kidney (n = 2) underwent combined sonography/ARFI imaging. Images were acquired of a total of 12 tumors in the nine patients. In all cases, boundary definition in ARFI images was improved or equivalent to boundary definition in B-mode images. Displacement contrast in ARFI images was superior to echo contrast in B-mode images for each tumor. The mean contrast for suspected hepatocellular carcinomas (HCCs) in B-mode images was 2.9 dB (range: 1.5-4.2) versus 7.5 dB (range: 3.1-11.9) in ARFI images, with all HCCs appearing more compliant than regional cirrhotic liver parenchyma. The mean contrast for metastases in B-mode images was 3.1 dB (range: 1.2-5.2) versus 9.3 dB (range: 5.7-13.9) in ARFI images, with all masses appearing less compliant than regional non-cirrhotic liver parenchyma. ARFI image contrast (10.4 dB) was superior to B-mode contrast (0.9 dB) for a renal mass. To our knowledge, we present the first in vivo images of abdominal malignancies in humans acquired with the ARFI method or any other technique of imaging tissue elasticity

  16. Acoustic radiation force induced resonance elastography of coagulating blood: theoretical viscoelasticity modeling and ex vivo experimentation

    Science.gov (United States)

    Bhatt, Manish; Montagnon, Emmanuel; Destrempes, François; Chayer, Boris; Kazemirad, Siavash; Cloutier, Guy

    2018-03-01

    Deep vein thrombosis is a common vascular disease that can lead to pulmonary embolism and death. The early diagnosis and clot age staging are important parameters for reliable therapy planning. This article presents an acoustic radiation force induced resonance elastography method for the viscoelastic characterization of clotting blood. The physical concept of this method relies on the mechanical resonance of the blood clot occurring at specific frequencies. Resonances are induced by focusing ultrasound beams inside the sample under investigation. Coupled to an analytical model of wave scattering, the ability of the proposed method to characterize the viscoelasticity of a mimicked venous thrombosis in the acute phase is demonstrated. Experiments with a gelatin-agar inclusion sample of known viscoelasticity are performed for validation and establishment of the proof of concept. In addition, an inversion method is applied in vitro for the kinetic monitoring of the blood coagulation process of six human blood samples obtained from two volunteers. The computed elasticity and viscosity values of blood samples at the end of the 90 min kinetics were estimated at 411  ±  71 Pa and 0.25  ±  0.03 Pa · s for volunteer #1, and 387  ±  35 Pa and 0.23  ±  0.02 Pa · s for volunteer #2, respectively. The proposed method allowed reproducible time-varying thrombus viscoelastic measurements from samples having physiological dimensions.

  17. Importance of aerosol non-sphericity in estimating aerosol radiative forcing in Indo-Gangetic Basin.

    Science.gov (United States)

    Srivastava, Parul; Dey, Sagnik; Srivastava, Atul Kumar; Singh, Sachchidanand; Mishra, S K; Tiwari, Suresh

    2017-12-01

    Aerosols are usually presumed spherical in shape while estimating the direct radiative forcing (DRF) using observations or in the models. In the Indo-Gangetic Basin (IGB), a regional aerosol hotspot where dust is a major aerosol species and has been observed to be non-spherical in shape, it is important to test the validity of this assumption. We address this issue using measured chemical composition at megacity Delhi, a representative site of the western IGB. Based on the observation, we choose three non-spherical shapes - spheroid, cylinder and chebyshev, and compute their optical properties. Non-spherical dust enhances aerosol extinction coefficient (β ext ) and single scattering albedo (SSA) at visible wavelengths by >0.05km -1 and >0.04 respectively, while it decreases asymmetry parameter (g) by ~0.1. Accounting non-sphericity leads top-of-the-atmosphere (TOA) dust DRF to more cooling due to enhanced backscattering and increases surface dimming due to enhanced β ext . Outgoing shortwave flux at TOA increases by up to 3.3% for composite aerosols with non-spherical dust externally mixed with other spherical species. Our results show that while non-sphericity needs to be accounted for, choice of shape may not be important in estimating aerosol DRF in the IGB. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Assessment of liver steatosis in chicken by using acoustic radiation force impulse imaging: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Guzman Aroca, Florentina; Serrano, Laura; Berna-Serna, Juan D.; Reus, Manuel [Virgen de la Arrixaca University Hospital, Department of Radiology, El Palmar, Murcia (Spain); Ayala, Ignacio [University of Murcia, Department of Animal Medicine and Surgery, Murcia (Spain); Castell, Maria T. [University of Murcia, Department of Cell Biology, Murcia (Spain); Garcia-Perez, Bartolome [Virgen de la Arrixaca University Hospital, Internal Medicine Service, El Palmar, Murcia (Spain)

    2010-10-15

    To evaluate acoustic radiation force impulse (ARFI) imaging as a non-invasive tool for quantification of the grades of liver steatosis in chickens. We used two different diets: a standard diet (SD group) and a hyperlipidaemic diet (HD group). The ARFI technique was performed in all the animals in the right hepatic lobe and shear wave velocity (SWV) was measured and expressed in metres per second (m/s). Plasma lipid levels were analysed. Steatosis was quantified by using semiquantitative analysis. Statistical analysis was used and Pearson's correlation coefficient was calculated. Mean SWV was 0.94 {+-} 0.16 m/s (range 0.8-1.3 m/s) in the SD group and 1.91 {+-} 0.25 m/s (range 1.3-2.2 m/s) in the HD group (p < 0.001). The lowest SWVs ({<=}1.3 m/s) corresponded to the chickens in the SD group, with 100% of the animals returning a score of 0, whereas the range of SWV in the HD group chickens was between 1.6 and 2.2 m/s. A substantial correlation was observed between SWVs with histological semiquantitative analysis of steatosis (r = 0.85, p < 0.001). ARFI imaging is a non-invasive diagnostic tool that allows discrimination between the grades of liver steatosis in chickens. (orig.)

  19. Asian Dust particles impacts on air quality and radiative forcing over Korea

    International Nuclear Information System (INIS)

    Kim, Y J; Noh, Y M; Song, C H; Yoon, S C; Han, J S

    2009-01-01

    Asian Dust particles originated from the deserts and loess areas of the Asian continent are often transported over Korea, Japan, and the North Pacific Ocean during spring season. Major air mass pathway of Asian dust storm to Korea is from either north-western Chinese desert regions or north-eastern Chinese sandy areas. The local atmospheric environment condition in Korea is greatly impacted by Asian dust particles transported by prevailing westerly wind. Since these Asian dust particles pass through heavily populated urban and industrial areas in China before it reach Korean peninsular, their physical, chemical and optical properties vary depending on the atmospheric conditions and air mass pathway characteristics. An integrated system approach has been adopted at the Advanced Environment Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST), Korea for effective monitoring of atmospheric aerosols utilizing various in-situ and optical remote sensing methods, which include a multi-channel Raman LIDAR system, sunphotometer, satellite, and in-situ instruments. Results from recent studies on impacts of Asian dust particles on local air quality and radiative forcing over Korea are summarized here.

  20. The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

    Science.gov (United States)

    Ganey, Gerard Q.; Loso, Michael G.; Burgess, Annie Bryant; Dial, Roman J.

    2017-10-01

    A lack of liquid water limits life on glaciers worldwide but specialized microbes still colonize these environments. These microbes reduce surface albedo, which, in turn, could lead to warming and enhanced glacier melt. Here we present results from a replicated, controlled field experiment to quantify the impact of microbes on snowmelt in red-snow communities. Addition of nitrogen-phosphorous-potassium fertilizer increased alga cell counts nearly fourfold, to levels similar to nitrogen-phosphorus-enriched lakes; water alone increased counts by half. The manipulated alga abundance explained a third of the observed variability in snowmelt. Using a normalized-difference spectral index we estimated alga abundance from satellite imagery and calculated microbial contribution to snowmelt on an icefield of 1,900 km2. The red-snow area extended over about 700 km2, and in this area we determined that microbial communities were responsible for 17% of the total snowmelt there. Our results support hypotheses that snow-dwelling microbes increase glacier melt directly in a bio-geophysical feedback by lowering albedo and indirectly by exposing low-albedo glacier ice. Radiative forcing due to perennial populations of microbes may match that of non-living particulates at high latitudes. Their contribution to climate warming is likely to grow with increased melt and nutrient input.

  1. Assessment of liver steatosis in chicken by using acoustic radiation force impulse imaging: preliminary results

    International Nuclear Information System (INIS)

    Guzman Aroca, Florentina; Serrano, Laura; Berna-Serna, Juan D.; Reus, Manuel; Ayala, Ignacio; Castell, Maria T.; Garcia-Perez, Bartolome

    2010-01-01

    To evaluate acoustic radiation force impulse (ARFI) imaging as a non-invasive tool for quantification of the grades of liver steatosis in chickens. We used two different diets: a standard diet (SD group) and a hyperlipidaemic diet (HD group). The ARFI technique was performed in all the animals in the right hepatic lobe and shear wave velocity (SWV) was measured and expressed in metres per second (m/s). Plasma lipid levels were analysed. Steatosis was quantified by using semiquantitative analysis. Statistical analysis was used and Pearson's correlation coefficient was calculated. Mean SWV was 0.94 ± 0.16 m/s (range 0.8-1.3 m/s) in the SD group and 1.91 ± 0.25 m/s (range 1.3-2.2 m/s) in the HD group (p < 0.001). The lowest SWVs (≤1.3 m/s) corresponded to the chickens in the SD group, with 100% of the animals returning a score of 0, whereas the range of SWV in the HD group chickens was between 1.6 and 2.2 m/s. A substantial correlation was observed between SWVs with histological semiquantitative analysis of steatosis (r = 0.85, p < 0.001). ARFI imaging is a non-invasive diagnostic tool that allows discrimination between the grades of liver steatosis in chickens. (orig.)

  2. Testicular microlithiasis and preliminary experience of acoustic radiation force impulse imaging

    International Nuclear Information System (INIS)

    Pedersen, Malene Roland; Osther, Palle Jørn Sloth; Rafaelsen, Søren Rafael

    2016-01-01

    Elastography of the testis can be used as a part of multiparametric examination of the scrotum. To determine the testicular stiffness using acoustic radiation force impulse imaging (ARFI) technique in men with testicular microlithiasis (TML). In 2013, 12 patients with diagnosed testicular microlithiasis in 2008 (mean age, 51 years; age range, 25–76 years) underwent a 5-year follow-up B-mode ultrasonography with three ARFI elastography measurements of each testis. We used a Siemens Acuson S3000 machine. No malignancy was found at the 5-year follow-up B-mode and elastography in 2013. However, we found an increase in TML; in the previous ultrasonography in 2008, eight men had bilateral TML, whereas in 2013, 10 men were diagnosed with bilateral TML. The mean elasticity of testicles with TML was 0.82 m/s (interquartile range [IQR], 0.72–0.88 m/s; range, 65–1.08 m/s). Elastography velocity of testis with TML seems to be in the same velocity range as in men with normal testis tissue

  3. Absorbing Aerosols Above Cloud: Detection, Quantitative Retrieval, and Radiative Forcing from Satellite-based Passive Sensors

    Science.gov (United States)

    Jethva, H.; Torres, O.; Remer, L. A.; Bhartia, P. K.

    2012-12-01

    , respectively. This study constitutes the first attempt to use non-polarized and non-lidar reflectance observations-both of them shown to have above-cloud aerosols retrieval capability, to retrieve above-cloud AOT by a passive non-polarized sensor. The uncertainty analysis suggests that the present method should retrieve above-cloud AOT within -10% to 50% which mainly arises due to uncertainty associated with the single-scattering albedo assumption. Although, currently tested by making use of OMI and MODIS measurements, the present color ratio method can be equally applied to the other satellite measurements that carry similar or near-by channels in VIS region of the spectrum such as MISR and NPP/VIIRS. The capability of quantifying the above-cloud aerosol load will facilitate several aspects of cloud-aerosol interaction research such as estimation of the direct radiative forcing of aerosols above clouds; the sign of which can be opposite (warming) to cloud-free aerosol forcing (cooling), aerosol transport, indirect effects of aerosols on clouds, and hydrological cycle.

  4. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    Directory of Open Access Journals (Sweden)

    Richard Talman

    2009-01-01

    2004 FEL Conference, pp. 18–21, MOCOS05, available at http://www.JACoW.org], a code with similar capabilities. For this comparison an appropriately new, 50 MeV, “standard chicane” is introduced. Unlike CSRTrack (which neglects vertical forces the present simulation shows substantial growth of vertical emittance. But “turning off” vertical forces in the UAL code (to match the CSRTrack treatment brings the two codes into excellent agreement. (iii Results are also obtained for 5 GeV electrons passing through a previously introduced “standard chicane” [Coherent Synchrotron Radiation, CSR Workshop, Berlin 2002, http://www.desy.de/csr] [of the sort needed for linear colliders and free electron lasers (FEL’s currently under design or construction]. Relatively little emittance growth is predicted for typical bunch parameters at such high electron energy. Results are obtained for both round beams and ribbon beams (like those actually needed in practice. Little or no excess emittance growth is found for ribbon bunches compared to round bunches of the same charge and bunch width. The UAL string space charge formulation (like TraFic4 and CSRTrack avoids the regularization step (subtracting the free-space space charge force which is required (to remove divergence in some methods. Also, by avoiding the need to calculate a retarded-time, four-dimensional field history, the computation time needed for realistic bunch evolution calculations is modest. Some theories of bunch dilution, because they ascribe emittance growth entirely to CSR, break down at low energy. In the present treatment, as well as CSR, all free-space Coulomb and magnetic space charge forces (but not image forces, and also the centrifugal space charge force (CSCF are included. Charge-dependent beam steering due to CSCF, as observed recently by Beutner et al. [B. Beutner et al., in Proceedings of FEL Conference, BESSY, Berlin, Germany, 2006, MOPPH009], is also investigated.

  5. Using ISCCP Weather States to Decompose Cloud Radiative Effects

    Science.gov (United States)

    Oreopoulos, L.; Rossow, W. B.

    2012-01-01

    The presentation will examine the shortwave (SW) and longwave (LW) cloud radiative effect CRE (aka "cloud radiative forcing") at the top-of-the-atmosphere and surface of ISCCP weather states (aka "cloud regimes") in three distinct geographical zones, one tropical and two mid-latitude. Our goal is to understand and quantify the contribution of the different cloud regimes to the planetary radiation budget. In the tropics we find that the three most convectively active states are the ones with largest SW, LW and net TOA CRE contributions to the overall daytime tropical CRE budget. They account for 59%, 71% and 55% of the total CRE, respectively. The boundary layer-dominated weather states account for only 34% of the total SW CRE and 41% of the total net CRE, so to focus only on them in cloud feedback studies may be imprudent. We also find that in both the northern and southern midlatitude zones only two weather states, the first and third most convectively active with large amounts of nimbostratus-type clouds, contribute ",40% to both the SW and net TOA CRE budgets, highlighting the fact that cloud regimes associated with frontal systems are not only important for weather (precipitation) but also for climate (radiation budget). While all cloud regimes in all geographical zones have a slightly larger SFC than TOA SW CRE, implying cooling of the surface and slight warming of the atmosphere, their LW radiative effects are more subtle: in the tropics the weather states with plentiful high clouds warm the atmosphere while those with copious amounts of low clouds cool the atmosphere. In both midlatitude zones only the weather states with peak cloud fractions at levels above 440 mbar warm the atmosphere while all the rest cool it. These results make the connection of the contrasting CRE effects to the atmospheric dynamics more explicit - "storms" tend to warm the atmosphere whereas fair weather clouds cool it, suggesting a positive feedback of clouds on weather systems. The

  6. The acoustic radiation force on a small thermoviscous or thermoelastic particle suspended in a viscous and heat-conducting fluid

    Science.gov (United States)

    Karlsen, Jonas; Bruus, Henrik

    2015-11-01

    We present a theoretical analysis (arxiv.org/abs/1507.01043) of the acoustic radiation force on a single small particle, either a thermoviscous fluid droplet or a thermoelastic solid particle, suspended in a viscous and heat-conducting fluid. Our analysis places no restrictions on the viscous and thermal boundary layer thicknesses relative to the particle radius, but it assumes the particle to be small in comparison to the acoustic wavelength. This is the limit relevant to scattering of ultrasound waves from sub-micrometer particles. For particle sizes smaller than the boundary layer widths, our theory leads to profound consequences for the acoustic radiation force. For example, for liquid droplets and solid particles suspended in gasses we predict forces orders of magnitude larger than expected from ideal-fluid theory. Moreover, for certain relevant choices of materials, we find a sign change in the acoustic radiation force on different-sized but otherwise identical particles. These findings lead to the concept of a particle-size-dependent acoustophoretic contrast factor, highly relevant to applications in acoustic levitation or separation of micro-particles in gases, as well as to handling of μm- and nm-sized particles such as bacteria and vira in lab-on-a-chip systems.

  7. Lateral expansion and carbon exchange of a boreal peatland in Finland resulting in 7000 years of positive radiative forcing

    Science.gov (United States)

    Mathijssen, Paul J. H.; Kähkölä, Noora; Tuovinen, Juha-Pekka; Lohila, Annalea; Minkkinen, Kari; Laurila, Tuomas; Väliranta, Minna

    2017-03-01

    Data on past peatland growth patterns, vegetation development, and carbon (C) dynamics during the various Holocene climate phases may help us to understand possible future climate-peatland feedback mechanisms. In this study, we analyzed and radiocarbon dated several peat cores from Kalevansuo, a drained bog in southern Finland. We investigated peatland succession and C dynamics throughout the Holocene. These data were used to reconstruct the long-term atmospheric radiative forcing, i.e., climate impact of the peatland since initiation. Kalevansuo peat records revealed a general development from fen to bog, typical for the southern boreal zone, but the timing of ombrotrophication varied in different parts of the peatland. Peat accumulation patterns and lateral expansion through paludification were influenced by fires and climate conditions. Long-term C accumulation rates were overall lower than the average values found from literature. We suggest the low accumulation rates are due to repeated burning of the peat surface. Drainage for forestry resulted in a nearly complete replacement of typical bog mosses by forest species within 40 years after drainage. The radiative forcing reconstruction suggested positive values (warming) for the first 7000 years following initiation. The change from positive to negative forcing was triggered by an expansion of bog vegetation cover and later by drainage. The strong relationship between peatland area and peat type with radiative forcing suggests a possible feedback for future changing climate, as high-latitude peatlands may experience prominent regime shifts, such as fen to bog transitions.

  8. Radiative forcing due to greenhouse gas emission and sink histories in Finland and its future control potential

    Energy Technology Data Exchange (ETDEWEB)

    Savolainen, I; Sinisalo, J; Pipatti, R [VTT Energy, Espoo (Finland)

    1996-12-31

    The effective atmospheric lifetimes of the greenhouse gases like carbon dioxide (CO{sub 2}),nitrous oxide (N{sub 2}O) and many of the CFCs are of the order of 100 years. Human activities, as an example GDP, very often change at rates of a few per cents per year,corresponding time constants of some tens of years. Also the forest ecosystems have time constants of this order. Even the human population of the globe is increasing by about two percent per year. Because so many natural and human-linked processes, which are relevant to global warming, have slow change rates of about same order, a time-dependent consideration of the greenhouse warming and its control can give useful information for the understanding of the problem. The objective of the work is to study the anthropogenic greenhouse gas emissions and sinks in Finland and their greenhouse impact as a function of time. The greenhouse impact is expressed in terms of radiative forcing which describes the perturbation in the Earth`s radiation budget. Radiative forcing allows a comparison of the impact of various greenhouse gases and their possible control options as a function of time. The idea behind the calculations is that Finland should in some way steer its share of the global radiative forcing and greenhouse effect. This presentation describes the calculation model REFUGE and the projects in which it has been used

  9. Radiative forcing due to greenhouse gas emission and sink histories in Finland and its future control potential

    Energy Technology Data Exchange (ETDEWEB)

    Savolainen, I.; Sinisalo, J.; Pipatti, R. [VTT Energy, Espoo (Finland)

    1995-12-31

    The effective atmospheric lifetimes of the greenhouse gases like carbon dioxide (CO{sub 2}),nitrous oxide (N{sub 2}O) and many of the CFCs are of the order of 100 years. Human activities, as an example GDP, very often change at rates of a few per cents per year,corresponding time constants of some tens of years. Also the forest ecosystems have time constants of this order. Even the human population of the globe is increasing by about two percent per year. Because so many natural and human-linked processes, which are relevant to global warming, have slow change rates of about same order, a time-dependent consideration of the greenhouse warming and its control can give useful information for the understanding of the problem. The objective of the work is to study the anthropogenic greenhouse gas emissions and sinks in Finland and their greenhouse impact as a function of time. The greenhouse impact is expressed in terms of radiative forcing which describes the perturbation in the Earth`s radiation budget. Radiative forcing allows a comparison of the impact of various greenhouse gases and their possible control options as a function of time. The idea behind the calculations is that Finland should in some way steer its share of the global radiative forcing and greenhouse effect. This presentation describes the calculation model REFUGE and the projects in which it has been used

  10. What is the impact of natural variability and aerosol-cloud interaction on the effective radiative forcing of anthropogenic aerosol?

    Science.gov (United States)

    Fiedler, S.; Stevens, B.; Mauritsen, T.

    2017-12-01

    State-of-the-art climate models have persistently shown a spread in estimates of the effective radiative forcing (ERF) associated with anthropogenic aerosol. Different reasons for the spread are known, but their relative importance is poorly understood. In this presentation we investigate the role of natural atmospheric variability, global patterns of aerosol radiative effects, and magnitudes of aerosol-cloud interaction in controlling the ERF of anthropogenic aerosol (Fiedler et al., 2017). We use the Earth system model MPI-ESM1.2 for conducting ensembles of atmosphere-only simulations and calculate the shortwave ERF of anthropogenic aerosol at the top of the atmosphere. The radiative effects are induced with the new parameterisation MACv2-SP (Stevens et al., 2017) that prescribes observationally constrained anthropogenic aerosol optical properties and an associated Twomey effect. Firstly, we compare the ERF of global patterns of anthropogenic aerosol from the mid-1970s and today. Our results suggest that such a substantial pattern difference has a negligible impact on the global mean ERF, when the natural variability of the atmosphere is considered. The clouds herein efficiently mask the clear-sky contributions to the forcing and reduce the detectability of significant anthropogenic aerosol radiative effects in all-sky conditions. Secondly, we strengthen the forcing magnitude through increasing the effect of aerosol-cloud interaction by prescribing an enhanced Twomey effect. In that case, the different spatial pattern of aerosol radiative effects from the mid-1970s and today causes a moderate change (15%) in the ERF of anthropogenic aerosol in our model. This finding lets us speculate that models with strong aerosol-cloud interactions would show a stronger ERF change with anthropogenic aerosol patterns. Testing whether the anthropogenic aerosol radiative forcing is model-dependent under prescribed aerosol conditions is currently ongoing work using MACv2-SP in

  11. Economic Value of Narrowing the Uncertainty in Climate Sensitivity: Decadal Change in Shortwave Cloud Radiative Forcing and Low Cloud Feedback

    Science.gov (United States)

    Wielicki, B. A.; Cooke, R. M.; Golub, A. A.; Mlynczak, M. G.; Young, D. F.; Baize, R. R.

    2016-12-01

    Several previous studies have been published on the economic value of narrowing the uncertainty in climate sensitivity (Cooke et al. 2015, Cooke et al. 2016, Hope, 2015). All three of these studies estimated roughly 10 Trillion U.S. dollars for the Net Present Value and Real Option Value at a discount rate of 3%. This discount rate is the nominal discount rate used in the U.S. Social Cost of Carbon Memo (2010). The Cooke et al studies approached this problem by examining advances in accuracy of global temperature measurements, while the Hope 2015 study did not address the type of observations required. While temperature change is related to climate sensitivity, large uncertainties of a factor of 3 in current anthropogenic radiative forcing (IPCC, 2013) would need to be solved for advanced decadal temperature change observations to assist the challenge of narrowing climate sensitivity. The present study takes a new approach by extending the Cooke et al. 2015,2016 papers to replace observations of temperature change to observations of decadal change in the effects of changing clouds on the Earths radiative energy balance, a measurement known as Cloud Radiative Forcing, or Cloud Radiative Effect. Decadal change in this observation is direclty related to the largest uncertainty in climate sensitivity which is cloud feedback from changing amount of low clouds, primarily low clouds over the world's oceans. As a result, decadal changes in shortwave cloud radiative forcing are more directly related to cloud feedback uncertainty which is the dominant uncertainty in climate sensitivity. This paper will show results for the new approach, and allow an examination of the sensitivity of economic value results to different observations used as a constraint on uncertainty in climate sensitivity. The analysis suggests roughly a doubling of economic value to 20 Trillion Net Present Value or Real Option Value at 3% discount rate. The higher economic value results from two changes: a

  12. Spectral Signature of Radiative Forcing by East Asian Dust-Soot Mixture

    Science.gov (United States)

    Zhu, A.; Ramanathan, V.

    2007-12-01

    The Pacific Dust Experiment (PACDEX) provides the first detailed sampling of dust-soot mixtures from the western Pacific to the eastern Pacific Ocean. The data includes down and up spectral irradiance, mixing state of dust and soot, and other aerosol properties. This study attempts to simulate the radiative forcing by dust-soot mixtures during the experimental period. The MODTRAN band model was employed to investigate the spectral signatures of solar irradiance change induced by aerosols at moderate spectral resolutions. For the short wave band (300-1100nm) used in this study, the reduction of downward irradiance at surface by aerosols greatly enhances with increasing wavelength in the UV band (300-400nm), reaches a maximum in the blue band, then gradually decreases toward the red band. In the near-IR band (700-1100nm), irradiance reduction by aerosols shows great fluctuations in the band with center wavelength at around 940nm, 820nm, 720nm, 760nm, 690nm, where the aerosol effect is overwhelmed by the water vapor and O2 absorptions. The spectral pattern of irradiance reduction varies for different aerosol species. The maximum reduction lies at around 450nm for soot, and shifting to about 490nm for East Asian mineral dust. It's worth noting that although soot aerosols reduce more irradiance than East Asian dust in the UV and blue band, the impact of dust to the irradiance exceeds that by soot at the longer wavelength band (i.e. around 550nm). The reduction of irradiance by East Asian dust (soot) in the UV band, visible band, and near-IR accounts for about 6% (10%), 56% (64%), and 38% (26%) of total irradiance reduction. As large amount of soot aerosols are involved during the long range transport of East Asian dust, the optical properties of dust aerosols are modified with different mixing state with soot, the spectral pattern of the irradiance reduction will be changed. The study of aerosol forcing at moderate spectral resolutions has the potential application for

  13. Tissue-mimicking bladder wall phantoms for evaluating acoustic radiation force-optical coherence elastography systems.

    Science.gov (United States)

    Ejofodomi, O'tega A; Zderic, Vesna; Zara, Jason M

    2010-04-01

    Acoustic radiation force-optical coherence elastography (ARF-OCE) systems are novel imaging systems that have the potential to simultaneously quantify and characterize the optical and mechanical properties of in vivo tissues. This article presents the construction of bladder wall phantoms for use in ARF-OCE systems. Mechanical, acoustic, and optical properties are reported and compared to published values for the urinary bladder. The phantom consisted of 0.2000 +/- 0.0089 and 6.0000 +/- 0.2830 microm polystyrene microspheres (Polysciences Inc., Warrington, PA, Catalog Nos. 07304 and 07312), 7.5 +/- 1.5 microm copolymer microspheres composed of acrylonitrile and vinylidene chloride, (Expancel, Duluth, GA, Catalog No. 461 DU 20), and bovine serum albumin within a gelatin matrix. Young's modulus was measured by successive compression of the phantom and obtaining the slope of the resulting force-displacement data. Acoustic measurements were performed using the transmission method. The phantoms were submerged in a water bath and placed between transmitting and receiving 13 mm diameter unfocused transducers operating at a frequency of 3.5 MHz. A MATLAB algorithm to extract the optical scattering coefficient from optical coherence tomography (OCT) images of the phantom was used. The phantoms possess a Young's modulus of 17.12 +/- 2.72 kPa, a mass density of 1.05 +/- 0.02 g/cm3, an acoustic attenuation coefficient of 0.66 +/- 0.08 dB/cm/MHz, a speed of sound of 1591 +/- 8.76 m/s, and an optical scattering coefficient of 1.80 +/- 0.23 mm(-1). Ultrasound and OCT images of the bladder wall phantom are presented. A material that mimics the mechanical, optical, and acoustic properties of healthy bladder wall has been developed. This tissue-mimicking bladder wall phantom was developed as a control tool to investigate the feasibility of using ARF-OCE to detect the mechanical and optical changes that may be indicative of the onset or development of cancer in the urinary bladder

  14. Net radiative forcing and air quality responses to regional CO emission reductions

    Directory of Open Access Journals (Sweden)

    M. M. Fry

    2013-05-01

    Full Text Available Carbon monoxide (CO emissions influence global and regional air quality and global climate change by affecting atmospheric oxidants and secondary species. We simulate the influence of halving anthropogenic CO emissions globally and individually from 10 regions on surface and tropospheric ozone, methane, and aerosol concentrations using a global chemical transport model (MOZART-4 for the year 2005. Net radiative forcing (RF is then estimated using the GFDL (Geophysical Fluid Dynamics Laboratory standalone radiative transfer model. We estimate that halving global CO emissions decreases global annual average concentrations of surface ozone by 0.45 ppbv, tropospheric methane by 73 ppbv, and global annual net RF by 36.1 mW m−2, nearly equal to the sum of changes from the 10 regional reductions. Global annual net RF per unit change in emissions and the 100 yr global warming potential (GWP100 are estimated as −0.124 mW m−2 (Tg CO−1 and 1.34, respectively, for the global CO reduction, and ranging from −0.115 to −0.131 mW m−2 (Tg CO−1 and 1.26 to 1.44 across 10 regions, with the greatest sensitivities for regions in the tropics. The net RF distributions show widespread cooling corresponding to the O3 and CH4 decreases, and localized positive and negative net RFs due to changes in aerosols. The strongest annual net RF impacts occur within the tropics (28° S–28° N followed by the northern midlatitudes (28° N–60° N, independent of reduction region, while the greatest changes in surface CO and ozone concentrations occur within the reduction region. Some regional reductions strongly influence the air quality in other regions, such as East Asia, which has an impact on US surface ozone that is 93% of that from North America. Changes in the transport of CO and downwind ozone production clearly exceed the direct export of ozone from each reduction region. The small variation in CO GWPs among world regions suggests that future international

  15. The cloud-radiative forcing of the U.S. landfalling atmospheric rivers

    Science.gov (United States)

    Luo, Qianwen

    Atmospheric rivers (ARs) are narrow channels in the atmosphere that transport an enormous amount of moisture from the tropics to the higher latitudes. Streaks of highly reflective clouds are observed along with the ARs in satellite imagery. These clouds both influence the moisture transport of ARs, as well as modify the Earth-Atmospheric energy budget through pathways such as cloud-radiative forcing (CRF). This dissertation studies the CRF of the U.S. Landfalling ARs in weather and climate scales. Three crucial questions are addressed. First, how do clouds produced by the ARs modulate the moisture and heat balance of the Earth-Atmospheric system? Even though studies of ARs date back to the 90s, past research has been primarily focused on their hydrological impacts. We addressed this research gap by comparing the dominant types of precipitating clouds and convection of two ARs. Through quantifying their effects on the energy balance in the midlatitudes, we found that when deep convection was the dominant cloud types of an AR, impressive CRF cooling was produced. Second, what are the sufficient climate conditions for the extensive CRF in the continental U.S.? We studied 60 ARs that reached the California coast (the Southwest ARs) and 60 ARs that reached Pacific Northwest during Nov-Mar, 2000-2008. It was found that when these West-Coast ARs were followed by the moisture surge from the Gulf of Mexico (the Gulf-Coast AR), it resulted in apparent statewide CRF. Such condition happened more frequently in the Southwest-AR scenario. Third, how does the subgrid-scale-convection-induced CRF influence the moisture transport of ARs?We ran two WRF ARW simulations for a Southwest-AR that was followed by a Gulf-Coast AR. The only difference between the two simulations was one considered the CRF of subgrid-scale clouds while the other did not. By comparing the two simulations, we found that the subgrid-scale-convection-induced CRF helped prolong the lifespan of clouds in an AR

  16. Radiative forcing over the conterminous United States due to contemporary land cover land use change and sensitivity to snow and interannual albedo variability

    Science.gov (United States)

    Barnes, Christopher A.; Roy, David P.

    2010-01-01

    Satellite-derived land cover land use (LCLU), snow and albedo data, and incoming surface solar radiation reanalysis data were used to study the impact of LCLU change from 1973 to 2000 on surface albedo and radiative forcing for 58 ecoregions covering 69% of the conterminous United States. A net positive surface radiative forcing (i.e., warming) of 0.029 Wm−2 due to LCLU albedo change from 1973 to 2000 was estimated. The forcings for individual ecoregions were similar in magnitude to current global forcing estimates, with the most negative forcing (as low as −0.367 Wm−2) due to the transition to forest and the most positive forcing (up to 0.337 Wm−2) due to the conversion to grass/shrub. Snow exacerbated both negative and positive forcing for LCLU transitions between snow-hiding and snow-revealing LCLU classes. The surface radiative forcing estimates were highly sensitive to snow-free interannual albedo variability that had a percent average monthly variation from 1.6% to 4.3% across the ecoregions. The results described in this paper enhance our understanding of contemporary LCLU change on surface radiative forcing and suggest that future forcing estimates should model snow and interannual albedo variation.

  17. Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. II. Radiation-Gas Interactions and Outflows

    Science.gov (United States)

    Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron

    2017-12-01

    Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.

  18. Global direct radiative forcing by process-parameterized aerosol optical properties

    Science.gov (United States)

    KirkevâG, Alf; Iversen, Trond

    2002-10-01

    A parameterization of aerosol optical parameters is developed and implemented in an extended version of the community climate model version 3.2 (CCM3) of the U.S. National Center for Atmospheric Research. Direct radiative forcing (DRF) by monthly averaged calculated concentrations of non-sea-salt sulfate and black carbon (BC) is estimated. Inputs are production-specific BC and sulfate from [2002] and background aerosol size distribution and composition. The scheme interpolates between tabulated values to obtain the aerosol single scattering albedo, asymmetry factor, extinction coefficient, and specific extinction coefficient. The tables are constructed by full calculations of optical properties for an array of aerosol input values, for which size-distributed aerosol properties are estimated from theory for condensation and Brownian coagulation, assumed distribution of cloud-droplet residuals from aqueous phase oxidation, and prescribed properties of the background aerosols. Humidity swelling is estimated from the Köhler equation, and Mie calculations finally yield spectrally resolved aerosol optical parameters for 13 solar bands. The scheme is shown to give excellent agreement with nonparameterized DRF calculations for a wide range of situations. Using IPCC emission scenarios for the years 2000 and 2100, calculations with an atmospheric global cliamte model (AFCM) yield a global net anthropogenic DRF of -0.11 and 0.11 W m-2, respectively, when 90% of BC from biomass burning is assumed anthropogenic. In the 2000 scenario, the individual DRF due to sulfate and BC has separately been estimated to -0.29 and 0.19 W m-2, respectively. Our estimates of DRF by BC per BC mass burden are lower than earlier published estimates. Some sensitivity tests are included to investigate to what extent uncertain assumptions may influence these results.

  19. Role of acoustic radiation force impulse elastography in the characterization of focal solid hepatic lesions

    Directory of Open Access Journals (Sweden)

    Harshavardhan Nagolu

    2018-01-01

    Full Text Available Objective: The purpose of the study is to investigate the usefulness of acoustic radiation force impulse (ARFI elastography in the characterization of focal solid liver lesions as benign, malignant, or metastatic using ARFI two-dimensional (2D imaging and ARFI quantification (shear wave velocities [SWVs]. Materials and Methods: Sixty lesions were included in this study. The lesions were classified into three groups: Group I included benign lesions (n = 25, Group II included malignant lesions (n = 27, and Group III included metastatic lesions (n = 8. ARFI elastography was performed in all these patients using a Siemens ACUSON S 2000TM ultrasound machine. Stiffness and size of the lesions were assessed on ARFI 2D images in correlation with B-mode ultrasound images. SWVs were obtained in these lesions for the quantification of stiffness. Results: In ARFI 2D images, malignant lesions were predominantly stiffer and larger, while benign lesions were softer and similar in size (P < 0.05. The mean SWVs in benign, malignant, and metastatic lesions were 1.30 ± 0.35 m/s, 2.93 ± 0.75 m/s, and 2.77 ± 0.90 m/s, respectively. The area under receiver operating characteristic curve of SWV for differentiating benign from malignant lesions was 0.877, suggesting fair accuracy (95% confidence interval: 0.777–0.976; with a cutoff value of 2 m/s, showing sensitivity: 92%; specificity: 96%; positive predictive value: 96%; negative predictive value: 93% (P < 0.05. Statistically significant difference exists in SWV of benign and malignant or metastatic lesions. Conclusion: ARFI elastography with 2D imaging and quantification might be useful in the characterization of benign and malignant liver lesions.

  20. Comparison between acoustic radiation force impulse quantification data and perfusion-CT parameters in hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Esser, Michael, E-mail: michael.esser@med.uni-tuebingen.de; Schneeweiß, Sven, E-mail: sven.schneeweiss@med.uni-tuebingen.de; Kolb, Manuel, E-mail: manuel.kolb@med.uni-tuebingen.de; Kurucay, Mustafa, E-mail: mustafa.kurucay@med.uni-tuebingen.de; Ruff, Christer, E-mail: christer.ruff@med.uni-tuebingen.de; Nikolaou, Konstantin, E-mail: konstantin.nikolaou@med.uni-tuebingen.de; Horger, Marius, E-mail: marius.horger@med.uni-tuebingen.de

    2017-04-15

    Highlights: • HCC tissue stiffness did not correlate with the degree of tumor vascularization. • HCC tissue stiffness declined while increasing HCC distance to the skin surface. • HCC tissue stiffness showed higher values the larger the respective tumor was. • Poorly differentiated HCCs showed increased values of tumor tissue stiffness. - Abstract: Objective: To find out, if ultrasound elastography of hepatocellular carcinoma (HCC) can predict patterns of tumor perfusion in volume perfusion computed tomography (VPCT). Material and methods: 25 consecutive patients (mean age, 68.9; range, 51–85 years) with liver cirrhosis suspected of HCC underwent VPCT and acoustic radiation force impulse (ARFI) elastography the same day. Quantitative elasticity values were registered, while blood flow (BF), blood volume (BV) and hepatic perfusion index (HPI) of the HCC lesions were calculated. Additionally, we identified histologic WHO grading, lesion size and localization. The Siemens Acuson S 3000 HELX-System with Virtual Touch™-Software and Siemens Somatom Definition Flash with Syngo{sup ®} software were used. Results: A total of 43 HCC lesions were assessed. Mean shear wave velocity was 2.6 m/s (range, 1.1–4.3 m/s). There was no significant linear correlation between the elasticity values and BF (p = 0.751), BV (p = 0.426) and HPI (p = 0.437). However, elasticity values were higher, the larger the tumor was (p = 0.008). Shear wave velocity declined with increasing distance of the HCC to the skin surface (p = 0.028) and depending on liver segment. In addition, elasticity values were higher in less differentiated HCCs. This trend was not statistically significant (p = 0.842). Conclusion: Tissue elasticity in HCC does not correlate with the degree of tumor vascularization, but calculated values are influenced both by the tumor size and localization inside the liver.

  1. Acoustic Radiation Force Impulse Elastography for Focal Hepatic Tumors: Usefulness for Differentiating Hemangiomas from Malignant Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Eun [Department of Radiology, Gyeongsang National University School of Medicine, Jinju 660-702 (Korea, Republic of); Lee, Jae Young [Department of Radiology and Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of); Bae, Kyung Soo [Department of Radiology, Gyeongsang National University School of Medicine, Jinju 660-702 (Korea, Republic of); Han, Joon Koo; Choi, Byung Ihn [Department of Radiology and Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744 (Korea, Republic of)

    2013-07-01

    The purpose of this study is to investigate whether acoustic radiation force impulse (ARFI) elastography with ARFI quantification and ARFI 2-dimensional (2D) imaging is useful for differentiating hepatic hemangiomas from malignant hepatic tumors. One-hundred-and-one tumors in 74 patients were included in this study: 28 hemangiomas, 26 hepatocellular carcinomas (HCCs), three cholangiocarcinomas (CCCs), 20 colon cancer metastases and 24 other metastases. B-mode ultrasound, ARFI 2D imaging, and ARFI quantification were performed in all tumors. Shear wave velocities (SWVs) of the tumors and the adjacent liver and their SWV differences were compared among the tumor groups. The ARFI 2D images were compared with B-mode images regarding the stiffness, conspicuity and size of the tumors. The mean SWV of the hemangiomas was significantly lower than the malignant hepatic tumor groups: hemangiomas, 1.80 ± 0.57 m/sec; HCCs, 2.66 ± 0.94 m/sec; CCCs, 3.27 ± 0.64 m/sec; colon cancer metastases, 3.70 ± 0.61 m/sec; and other metastases, 2.82 ± 0.96 m/sec (p < 0.05). The area under the receiver operating characteristics curve of SWV for differentiating hemangiomas from malignant tumors was 0.86, with a sensitivity of 96.4% and a specificity of 65.8% at a cut-off value of 2.73 m/sec (p < 0.05). In the ARFI 2D images, the malignant tumors except HCCs were stiffer and more conspicuous as compared with the hemangiomas (p < 0.05). ARFI elastography with ARFI quantification and ARFI 2D imaging may be useful for differentiating hepatic hemangiomas from malignant hepatic tumors.

  2. Global source attribution of sulfate concentration and direct and indirect radiative forcing

    Directory of Open Access Journals (Sweden)

    Y. Yang

    2017-07-01

    Full Text Available The global source–receptor relationships of sulfate concentrations, and direct and indirect radiative forcing (DRF and IRF from 16 regions/sectors for years 2010–2014 are examined in this study through utilizing a sulfur source-tagging capability implemented in the Community Earth System Model (CESM with winds nudged to reanalysis data. Sulfate concentrations are mostly contributed by local emissions in regions with high emissions, while over regions with relatively low SO2 emissions, the near-surface sulfate concentrations are primarily attributed to non-local sources from long-range transport. Regional source efficiencies of sulfate concentrations are higher over regions with dry atmospheric conditions and less export, suggesting that lifetime of aerosols, together with regional export, is important in determining regional air quality. The simulated global total sulfate DRF is −0.42 W m−2, with −0.31 W m−2 contributed by anthropogenic sulfate and −0.11 W m−2 contributed by natural sulfate, relative to a state with no sulfur emissions. In the Southern Hemisphere tropics, dimethyl sulfide (DMS contributes 17–84 % to the total DRF. East Asia has the largest contribution of 20–30 % over the Northern Hemisphere mid- and high latitudes. A 20 % perturbation of sulfate and its precursor emissions gives a sulfate incremental IRF of −0.44 W m−2. DMS has the largest contribution, explaining −0.23 W m−2 of the global sulfate incremental IRF. Incremental IRF over regions in the Southern Hemisphere with low background aerosols is more sensitive to emission perturbation than that over the polluted Northern Hemisphere.

  3. Global source attribution of sulfate concentration and direct and indirect radiative forcing

    Science.gov (United States)

    Yang, Yang; Wang, Hailong; Smith, Steven J.; Easter, Richard; Ma, Po-Lun; Qian, Yun; Yu, Hongbin; Li, Can; Rasch, Philip J.

    2017-07-01

    The global source-receptor relationships of sulfate concentrations, and direct and indirect radiative forcing (DRF and IRF) from 16 regions/sectors for years 2010-2014 are examined in this study through utilizing a sulfur source-tagging capability implemented in the Community Earth System Model (CESM) with winds nudged to reanalysis data. Sulfate concentrations are mostly contributed by local emissions in regions with high emissions, while over regions with relatively low SO2 emissions, the near-surface sulfate concentrations are primarily attributed to non-local sources from long-range transport. Regional source efficiencies of sulfate concentrations are higher over regions with dry atmospheric conditions and less export, suggesting that lifetime of aerosols, together with regional export, is important in determining regional air quality. The simulated global total sulfate DRF is -0.42 W m-2, with -0.31 W m-2 contributed by anthropogenic sulfate and -0.11 W m-2 contributed by natural sulfate, relative to a state with no sulfur emissions. In the Southern Hemisphere tropics, dimethyl sulfide (DMS) contributes 17-84 % to the total DRF. East Asia has the largest contribution of 20-30 % over the Northern Hemisphere mid- and high latitudes. A 20 % perturbation of sulfate and its precursor emissions gives a sulfate incremental IRF of -0.44 W m-2. DMS has the largest contribution, explaining -0.23 W m-2 of the global sulfate incremental IRF. Incremental IRF over regions in the Southern Hemisphere with low background aerosols is more sensitive to emission perturbation than that over the polluted Northern Hemisphere.

  4. Renal shear wave velocity by acoustic radiation force impulse did not reflect advanced renal impairment.

    Science.gov (United States)

    Takata, Tomoaki; Koda, Masahiko; Sugihara, Takaaki; Sugihara, Shinobu; Okamoto, Toshiaki; Miyoshi, Kenichi; Matono, Tomomitsu; Hosho, Keiko; Mae, Yukari; Iyama, Takuji; Fukui, Takeaki; Fukuda, Satoko; Munemura, Chishio; Isomoto, Hajime

    2016-12-01

    Acoustic radiation force impulse is a noninvasive method for evaluating tissue elasticity on ultrasound. Renal shear wave velocity measured by this technique has not been fully investigated in patients with renal disease. The aim of the present study was to compare renal shear wave velocity in end-stage renal disease patients and that in patients without chronic kidney disease and to investigate influencing factors. Renal shear wave velocities were measured in 59 healthy young subjects (control group), 31 subjects without chronic kidney disease (non-CKD group), and 39 end-stage renal disease patients (ESRD group). Each measurement was performed 10 times at both kidneys, and the mean value of eight of 10 measurements, excluding the maximum and minimum values, was compared. Renal shear wave velocity could be measured in all subjects. Renal shear wave velocity in the control group was higher than in the non-CKD group and in the ESRD group, and no difference was found between the non-CKD group and the ESRD group. Age and depth were negatively correlated to the renal shear wave velocity. In multiple regression analysis, age and depth were independent factors for renal shear wave velocity, while renal impairment was not. There was no difference between the non-CKD group and the ESRD group, even when ages were matched and depth was adjusted. Renal shear wave velocity was not associated with advanced renal impairment. However, it reflected alteration of renal aging, and this technique may be useful to detect renal impairment in the earlier stages. © 2015 Asian Pacific Society of Nephrology.

  5. Phase Aberration and Attenuation Effects on Acoustic Radiation Force-Based Shear Wave Generation.

    Science.gov (United States)

    Carrascal, Carolina Amador; Aristizabal, Sara; Greenleaf, James F; Urban, Matthew W

    2016-02-01

    Elasticity is measured by shear wave elasticity imaging (SWEI) methods using acoustic radiation force to create the shear waves. Phase aberration and tissue attenuation can hamper the generation of shear waves for in vivo applications. In this study, the effects of phase aberration and attenuation in ultrasound focusing for creating shear waves were explored. This includes the effects of phase shifts and amplitude attenuation on shear wave characteristics such as shear wave amplitude, shear wave speed, shear wave center frequency, and bandwidth. Two samples of swine belly tissue were used to create phase aberration and attenuation experimentally. To explore the phase aberration and attenuation effects individually, tissue experiments were complemented with ultrasound beam simulations using fast object-oriented C++ ultrasound simulator (FOCUS) and shear wave simulations using finite-element-model (FEM) analysis. The ultrasound frequency used to generate shear waves was varied from 3.0 to 4.5 MHz. Results: The measured acoustic pressure and resulting shear wave amplitude decreased approximately 40%-90% with the introduction of the tissue samples. Acoustic intensity and shear wave displacement were correlated for both tissue samples, and the resulting Pearson's correlation coefficients were 0.99 and 0.97. Analysis of shear wave generation with tissue samples (phase aberration and attenuation case), measured phase screen, (only phase aberration case), and FOCUS/FEM model (only attenuation case) showed that tissue attenuation affected the shear wave generation more than tissue aberration. Decreasing the ultrasound frequency helped maintain a focused beam for creation of shear waves in the presence of both phase aberration and attenuation.

  6. Differential diagnosis of idiopathic granulomatous mastitis and breast cancer using acoustic radiation force impulse imaging.

    Science.gov (United States)

    Teke, Memik; Teke, Fatma; Alan, Bircan; Türkoğlu, Ahmet; Hamidi, Cihad; Göya, Cemil; Hattapoğlu, Salih; Gumus, Metehan

    2017-01-01

    Differentiation of idiopathic granulomatous mastitis (IGM) from carcinoma with routine imaging methods, such as ultrasonography (US) and mammography, is difficult. Therefore, we evaluated the value of a newly developed noninvasive technique called acoustic radiation force impulse imaging in differentiating IGM versus malignant lesions in the breast. Four hundred and eighty-six patients, who were referred to us with a presumptive diagnosis of a mass, underwent Virtual Touch tissue imaging (VTI; Siemens) and Virtual Touch tissue quantification (VTQ; Siemens) after conventional gray-scale US. US-guided percutaneous needle biopsy was then performed on 276 lesions with clinically and radiologically suspicious features. Malignant lesions (n = 122) and IGM (n = 48) were included in the final study group. There was a statistically significant difference in shear wave velocity marginal and internal values between the IGM and malignant lesions. The median marginal velocity for IGM and malignant lesions was 3.19 m/s (minimum-maximum 2.49-5.82) and 5.05 m/s (minimum-maximum 2.09-8.46), respectively (p < 0.001). The median internal velocity for IGM and malignant lesions was 2.76 m/s (minimum-maximum 1.14-4.12) and 4.79 m/s (minimum-maximum 2.12-8.02), respectively (p < 0.001). The combination of VTI and VTQ as a complement to conventional US provides viscoelastic properties of tissues, and thus has the potential to increase the specificity of US.

  7. Acoustic radiation force impulse shear wave elastography (ARFI) of acute and chronic pancreatitis and pancreatic tumor

    Energy Technology Data Exchange (ETDEWEB)

    Goertz, Ruediger S., E-mail: ruediger.goertz@uk-erlangen.de; Schuderer, Johanna, E-mail: Johanna@schuderer-floss.de; Strobel, Deike, E-mail: deike.strobel@uk-erlangen.de; Pfeifer, Lukas, E-mail: Lukas.Pfeifer@uk-erlangen.de; Neurath, Markus F., E-mail: Markus.Neurath@uk-erlangen.de; Wildner, Dane, E-mail: Dane.Wildner@uk-erlangen.de

    2016-12-15

    Highlights: • ARFI elastography of the pancreas is feasible. • Shear wave velocities in patients with acute or chronic pancreatitis or carcinoma are higher than those occurring in normal tissue. • ARFI values considerable overlap between different pathologies. - Abstract: Introduction: Acoustic Radiation Force Impulse (ARFI) elastography evaluates tissue stiffness non-invasively and has rarely been applied to pancreas examinations so far. In a prospective and retrospective analysis, ARFI shear wave velocities of healthy parenchyma, pancreatic lipomatosis, acute and chronic pancreatitis, adenocarcinoma and neuroendocrine tumor (NET) of the pancreas were evaluated and compared. Material and methods: In 95 patients ARFI elastography of the pancreatic head, and also of the tail for a specific group, was analysed retrospectively. Additionally, prospectively in 100 patients ARFI was performed in the head and tail of the pancreas. Results: A total of 195 patients were included in the study. Healthy parenchyma (n = 21) and lipomatosis (n = 30) showed similar shear wave velocities of about 1.3 m/s. Acute pancreatitis (n = 35), chronic pancreatitis (n = 53) and adenocarcinoma (n = 52) showed consecutively increasing ARFI values, respectively. NET (n = 4) revealed the highest shear wave velocities amounting to 3.62 m/s. ARFI elastography showed relevant differences between acute pancreatitis and chronic pancreatitis or adenocarcinoma. With a cut-off value of 1.74 m/s for the diagnosis of a malignant disease the sensitivity was 91.1% whereas the specificity amounted to 60.4%. Conclusion: ARFI shear wave velocities present differences in various pathologies of the pancreas. Acute and chronic pancreatitis as well as neoplastic lesions show high ARFI values. Very high elasticity values may indicate malignant disease of the pancreas. However, there is a considerable overlap between the entities.

  8. Atomic force imaging microscopy investigation of the interaction of ultraviolet radiation with collagen thin films

    Science.gov (United States)

    Stylianou, A.; Yova, D.; Alexandratou, E.; Petri, A.

    2013-02-01

    Collagen is the major fibrous protein in the extracellular matrix and consists a significant component of skin, bone, cartilage and tendon. Due to its unique properties, it has been widely used as scaffold or culture substrate for tissue regeneration or/and cell-substrate interaction studies. The ultraviolet light-collagen interaction investigations are crucial for the improvement of many applications such as that of the UV irradiation in the field of biomaterials, as sterilizing and photo-cross-linking method. The aim of this paper was to investigate the mechanisms of UV-collagen interactions by developing a collagen-based, well characterized, surface with controlled topography of collagen thin films in the nanoscale range. The methodology was to quantify the collagen surface modification induced on ultraviolet radiation and correlate it with changes induced in cells. Surface nanoscale characterization was performed by Atomic Force Microscopy (AFM) which is a powerful tool and offers quantitative and qualitative information with a non-destructive manner. In order to investigate cells behavior, the irradiated films were used for in vitro cultivation of human skin fibroblasts and the cells morphology, migration and alignment were assessed with fluorescence microscopy imaging and image processing methods. The clarification of the effects of UV light on collagen thin films and the way of cells behavior to the different modifications that UV induced to the collagen-based surfaces will contribute to the better understanding of cell-matrix interactions in the nanoscale and will assist the appropriate use of UV light for developing biomaterials.

  9. Acoustic radiation force impulse shear wave elastography (ARFI) of acute and chronic pancreatitis and pancreatic tumor

    International Nuclear Information System (INIS)

    Goertz, Ruediger S.; Schuderer, Johanna; Strobel, Deike; Pfeifer, Lukas; Neurath, Markus F.; Wildner, Dane

    2016-01-01

    Highlights: • ARFI elastography of the pancreas is feasible. • Shear wave velocities in patients with acute or chronic pancreatitis or carcinoma are higher than those occurring in normal tissue. • ARFI values considerable overlap between different pathologies. - Abstract: Introduction: Acoustic Radiation Force Impulse (ARFI) elastography evaluates tissue stiffness non-invasively and has rarely been applied to pancreas examinations so far. In a prospective and retrospective analysis, ARFI shear wave velocities of healthy parenchyma, pancreatic lipomatosis, acute and chronic pancreatitis, adenocarcinoma and neuroendocrine tumor (NET) of the pancreas were evaluated and compared. Material and methods: In 95 patients ARFI elastography of the pancreatic head, and also of the tail for a specific group, was analysed retrospectively. Additionally, prospectively in 100 patients ARFI was performed in the head and tail of the pancreas. Results: A total of 195 patients were included in the study. Healthy parenchyma (n = 21) and lipomatosis (n = 30) showed similar shear wave velocities of about 1.3 m/s. Acute pancreatitis (n = 35), chronic pancreatitis (n = 53) and adenocarcinoma (n = 52) showed consecutively increasing ARFI values, respectively. NET (n = 4) revealed the highest shear wave velocities amounting to 3.62 m/s. ARFI elastography showed relevant differences between acute pancreatitis and chronic pancreatitis or adenocarcinoma. With a cut-off value of 1.74 m/s for the diagnosis of a malignant disease the sensitivity was 91.1% whereas the specificity amounted to 60.4%. Conclusion: ARFI shear wave velocities present differences in various pathologies of the pancreas. Acute and chronic pancreatitis as well as neoplastic lesions show high ARFI values. Very high elasticity values may indicate malignant disease of the pancreas. However, there is a considerable overlap between the entities.

  10. Impact of springtime biomass-burning aerosols on radiative forcing over northern Thailand during the 7SEAS campaign

    Science.gov (United States)

    Pani, Shantanu Kumar; Wang, Sheng-Hsiang; Lin, Neng-Huei; Lee, Chung-Te; Tsay, Si-Chee; Holben, Brent; Janjai, Serm; Hsiao, Ta-Chih; Chuang, Ming-Tung; Chantara, Somporn

    2016-04-01

    dominate the both surface mass concentration and the columnar burden. The BC contributed only 6% to the aerosol mass loading, but its contribution to the total AOD and net atmospheric forcing were 12% and 75%, respectively. The mean radiative forcing was -6.8 to -8.7 W m-2 at the top-of-atmosphere and -28 to -33 W m-2 at surface. Furthermore BC aerosols contributed 45-49% to the surface radiative forcing along with the water soluble aerosols (49-52%), thus, significantly contributing to solar dimming

  11. Ozone database in support of CMIP5 simulations: results and corresponding radiative forcing

    Directory of Open Access Journals (Sweden)

    I. Cionni

    2011-11-01

    total column ozone is overestimated in the southern polar latitudes during spring and tropospheric column ozone is slightly underestimated. Vertical profiles of tropospheric ozone are broadly consistent with ozonesondes and in-situ measurements, with some deviations in regions of biomass burning. The tropospheric ozone radiative forcing (RF from the 1850s to the 2000s is 0.23 W m−2, lower than previous results. The lower value is mainly due to (i a smaller increase in biomass burning emissions; (ii a larger influence of stratospheric ozone depletion on upper tropospheric ozone at high southern latitudes; and possibly (iii a larger influence of clouds (which act to reduce the net forcing compared to previous radiative forcing calculations. Over the same period, decreases in stratospheric ozone, mainly at high latitudes, produce a RF of −0.08 W m−2, which is more negative than the central Intergovernmental Panel on Climate Change (IPCC Fourth Assessment Report (AR4 value of −0.05 W m−2, but which is within the stated range of −0.15 to +0.05 W m−2. The more negative value is explained by the fact that the regression model simulates significant ozone depletion prior to 1979, in line with the increase in EESC and as confirmed by CCMs, while the AR4 assumed no change in stratospheric RF prior to 1979. A negative RF of similar magnitude persists into the future, although its location shifts from high latitudes to the tropics. This shift is due to increases in polar stratospheric ozone, but decreases in tropical lower stratospheric ozone, related to a strengthening of the Brewer-Dobson circulation, particularly through the latter half of the 21st century. Differences in trends in tropospheric ozone among the four RCPs are mainly driven by different methane concentrations, resulting in a range of tropospheric ozone RFs between 0.4 and 0.1 W m−2 by 2100. The ozone dataset described here has been released for

  12. Interannual Variability in Radiative Forcing and Snowmelt Rates by Desert Dust in Snowcover in the Colorado River Basin

    Science.gov (United States)

    Skiles, S.; Painter, T. H.; Barrett, A. P.; Landry, C.; Deems, J. S.; Winstral, A. H.

    2010-12-01

    Dust in snow accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. Since the Anglo expansion and disturbance of the western US that began in the mid 19th century, the mountain snow cover of the Colorado River Basin has been subject to five-fold greater dust loading. This research expands on the work done in Painter et al. (2007) by assessing the interannual variability in radiative forcing, melt rates, and shortening of snow cover duration from 2005 to 2010, and the relative response of melt rates to simulated increases in air temperature. We ran the SNOBAL snowmelt model over the 6 year energy balance record at the alpine and subalpine towers in the Senator Beck Basin Study Area, San Juan Mountains, Colorado, USA. Observations indicate that dust concentrations are not correlated with total number of dust events and that dust loading and concentrations vary by an order of magnitude during the 6 year record. Our modeling results indicate that the number of days that dust advances retreat of snow cover and cumulative radiative forcing are linearly related to total dust concentration. Over the 6 years of record we have shown that for all years dust advances melt relative to a clean snowpack, even in lowest dust concentration years melt is advanced by up to 26 days. The greatest dust radiative impact occurred in 2009, when snow cover duration was shortened by 50 days, and the highest observed end of year dust concentrations reduced visible albedo to less than 0.35 during the last three weeks of snowcover. This work also shows that dust radiative forcing has a markedly greater impact on snow cover duration than increases in temperature. In the presence of dust there is little impact from temperature increases of 2 °C and 4 °C (0-4 days) and, in the absence of dust radiative forcing, temperature increases shorten snow cover duration by 5-18 days, compared with the 26

  13. Interagency task force on the health effects of ionizing radiation: report of the work group on records and privacy

    International Nuclear Information System (INIS)

    1979-06-01

    Research scientists studying the health effects of ionizing radiation have expressed the view that their work is sometimes impeded by legal restrictions on access to necessary records. In light of the critical importance of scientifically sound, efficient, and timely epidemiological research to resolve the difficult issues raised by the President's memorandum, the Task Force determined to inquire into the extent of this problem, and to ascertain whether new legislation or regulation was needed to eliminate serious roadblocks

  14. Contribution of anthropogenic aerosols in direct radiative forcing and atmospheric heating rate over Delhi in the Indo-Gangetic Basin.

    Science.gov (United States)

    Srivastava, Atul K; Singh, Sachchidanand; Tiwari, S; Bisht, D S

    2012-05-01

    The present work is aimed to understand direct radiation effects due to aerosols over Delhi in the Indo-Gangetic Basin (IGB) region, using detailed chemical analysis of surface measured aerosols during the year 2007. An optically equivalent aerosol model was formulated on the basis of measured aerosol chemical compositions along with the ambient meteorological parameters to derive radiatively important aerosol optical parameters. The derived aerosol parameters were then used to estimate the aerosol direct radiative forcing at the top of the atmosphere, surface, and in the atmosphere. The anthropogenic components measured at Delhi were found to be contributing ∼ 72% to the composite aerosol optical depth (AOD(0.5) ∼ 0.84). The estimated mean surface and atmospheric forcing for composite aerosols over Delhi were found to be about -69, -85, and -78 W m(-2) and about +78, +98, and +79 W m(-2) during the winter, summer, and post-monsoon periods, respectively. The anthropogenic aerosols contribute ∼ 90%, 53%, and 84% to the total aerosol surface forcing and ∼ 93%, 54%, and 88% to the total aerosol atmospheric forcing during the above respective periods. The mean (± SD) surface and atmospheric forcing for composite aerosols was about -79 (± 15) and +87 (± 26) W m(-2) over Delhi with respective anthropogenic contributions of ∼ 71% and 75% during the overall period of observation. Aerosol induced large surface cooling, which was relatively higher during summer as compared to the winter suggesting an increase in dust loading over the station. The total atmospheric heating rate at Delhi averaged during the observation was found to be 2.42  ±  0.72 K day(-1), of which the anthropogenic fraction contributed as much as ∼ 73%.

  15. Observed linkages between the northern annular mode/North Atlantic Oscillation, cloud incidence, and cloud radiative forcing

    Science.gov (United States)

    Li, Ying; Thompson, David W. J.; Huang, Yi; Zhang, Minghong

    2014-03-01

    The signature of the northern annular mode/North Atlantic Oscillation (NAM/NAO) in the vertical and horizontal distribution of tropospheric cloudiness is investigated in CloudSat and CALIPSO data from June 2006 to April 2011. During the Northern Hemisphere winter, the positive polarity of the NAM/NAO is marked by increases in zonally averaged cloud incidence north of ~60°N, decreases between ~25 and 50°N, and increases in the subtropics. The tripolar-like anomalies in cloud incidence associated with the NAM/NAO are largest over the North Atlantic Ocean basin/Middle East and are physically consistent with the NAM/NAO-related anomalies in vertical motion. Importantly, the NAM/NAO-related anomalies in tropospheric cloud incidence lead to significant top of atmosphere cloud radiative forcing anomalies that are comparable in amplitude to those associated with the NAM/NAO-related temperature anomalies. The results provide observational evidence that the most prominent pattern of Northern Hemisphere climate variability is significantly linked to variations in cloud radiative forcing. Implications for two-way feedback between extratropical dynamics and cloud radiative forcing are discussed.

  16. Radiative forcing by aerosols as derived from the AeroCom present-day and pre-industrial simulations

    Directory of Open Access Journals (Sweden)

    M. Schulz

    2006-01-01

    Full Text Available Nine different global models with detailed aerosol modules have independently produced instantaneous direct radiative forcing due to anthropogenic aerosols. The anthropogenic impact is derived from the difference of two model simulations with prescribed aerosol emissions, one for present-day and one for pre-industrial conditions. The difference in the solar energy budget at the top of the atmosphere (ToA yields a new harmonized estimate for the aerosol direct radiative forcing (RF under all-sky conditions. On a global annual basis RF is −0.22 Wm−2, ranging from +0.04 to −0.41 Wm−2, with a standard deviation of ±0.16 Wm−2. Anthropogenic nitrate and dust are not included in this estimate. No model shows a significant positive all-sky RF. The corresponding clear-sky RF is −0.68 Wm−2. The cloud-sky RF was derived based on all-sky and clear-sky RF and modelled cloud cover. It was significantly different from zero and ranged between −0.16 and +0.34 Wm−2. A sensitivity analysis shows that the total aerosol RF is influenced by considerable diversity in simulated residence times, mass extinction coefficients and most importantly forcing efficiencies (forcing per unit optical depth. The clear-sky forcing efficiency (forcing per unit optical depth has diversity comparable to that for the all-sky/ clear-sky forcing ratio. While the diversity in clear-sky forcing efficiency is impacted by factors such as aerosol absorption, size, and surface albedo, we can show that the all-sky/clear-sky forcing ratio is important because all-sky forcing estimates require proper representation of cloud fields and the correct relative altitude placement between absorbing aerosol and clouds. The analysis of the sulphate RF shows that long sulphate residence times are compensated by low mass extinction coefficients and vice versa. This is explained by more sulphate particle humidity growth and thus higher extinction in those models where short-lived sulphate

  17. Three-body radiative heat transfer and Casimir-Lifshitz force out of thermal equilibrium for arbitrary bodies

    Science.gov (United States)

    Messina, Riccardo; Antezza, Mauro

    2014-05-01

    We study the Casimir-Lifshitz force and the radiative heat transfer in a system consisting of three bodies held at three independent temperatures and immersed in a thermal environment, the whole system being in a stationary configuration out of thermal equilibrium. The theory we develop is valid for arbitrary bodies, i.e., for any set of temperatures, dielectric, and geometrical properties, and describes each body by means of its scattering operators. For the three-body system we provide a closed-form unified expression of the radiative heat transfer and of the Casimir-Lifshitz force (both in and out of thermal equilibrium). This expression is thus first applied to the case of three planar parallel slabs. In this context we discuss the nonadditivity of the force at thermal equilibrium, as well as the equilibrium temperature of the intermediate slab as a function of its position between two external slabs having different temperatures. Finally, we consider the force acting on an atom inside a planar cavity. We show that, differently from the equilibrium configuration, the absence of thermal equilibrium admits one or more positions of minima for the atomic potential. While the corresponding atomic potential depths are very small for typical ground-state atoms, they may become particularly relevant for Rydberg atoms, becoming a promising tool to produce an atomic trap.

  18. Attribution of aerosol radiative forcing over India during the winter monsoon to emissions from source categories and geographical regions

    Science.gov (United States)

    Verma, S.; Venkataraman, C.; Boucher, O.

    2011-08-01

    We examine the aerosol radiative effects due to aerosols emitted from different emission sectors (anthropogenic and natural) and originating from different geographical regions within and outside India during the northeast (NE) Indian winter monsoon (January-March). These studies are carried out through aerosol transport simulations in the general circulation (GCM) model of the Laboratoire de Météorologie Dynamique (LMD). The model estimates of aerosol single scattering albedo (SSA) show lower values (0.86-0.92) over the region north to 10°N comprising of the Indian subcontinent, Bay of Bengal, and parts of the Arabian Sea compared to the region south to 10°N where the estimated SSA values lie in the range 0.94-0.98. The model estimated SSA is consistent with the SSA values inferred through measurements on various platforms. Aerosols of anthropogenic origin reduce the incoming solar radiation at the surface by a factor of 10-20 times the reduction due to natural aerosols. At the top-of-atmosphere (TOA), aerosols from biofuel use cause positive forcing compared to the negative forcing from fossil fuel and natural sources in correspondence with the distribution of SSA which is estimated to be the lowest (0.7-0.78) from biofuel combustion emissions. Aerosols originating from India and Africa-west Asia lead to the reduction in surface radiation (-3 to -8 W m -2) by 40-60% of the total reduction in surface radiation due to all aerosols over the Indian subcontinent and adjoining ocean. Aerosols originating from India and Africa-west Asia also lead to positive radiative effects at TOA over the Arabian Sea, central India (CNI), with the highest positive radiative effects over the Bay of Bengal and cause either negative or positive effects over the Indo-Gangetic plain (IGP).

  19. Investigating the Linear Dependence of Direct and Indirect Radiative Forcing on Emission of Carbonaceous Aerosols in a Global Climate Model

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yanju [Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana IL USA; Wang, Hailong [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Singh, Balwinder [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Ma, Po-Lun [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Rasch, Philip J. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland WA USA; Bond, Tami C. [Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana IL USA

    2018-02-02

    The linearity of dependence of aerosol direct and indirect radiative forcing (DRF and IRF) on emissions is essential to answer the policy-relevant question on how the change in forcing would result from a change in emission. In this study, the forcing-to-emission relationship is investigated for black carbon (BC) and primary organic carbon (OC) emitted from North America and Asia. Direct and indirect radiative forcing of BC and OC are simulated with the Community Atmosphere Model (CAM5.1). Two diagnostics are introduced to aid in policy-relevant discussion: emission-normalized forcing (ENF) and linearity (R). DRF is linearly related to emission for both BC and OC from the two regions and emission-normalized DRF is similar, within 15%. IRF is linear to emissions for weaker sources and regions far from source (North American BC and OC), while for large emission sources and near source regions (Asian OC) the response of forcing to emission is sub-linear. In North America emission-normalized IRF (ENIRF) is 2-4 times higher than that in Asia. The difference among regions and species is primarily caused by failure of accumulation mode particles to become CCN, and then to activate into CDNC. Optimal aggregation area (30ºx 30º) has been used to communicate the regional variation of forcing-to-emission relationship. For IRF, only 15-40% of the Earth’s surface is significantly affected by the two emission regions, but the forcing in these regions comprises most of the global impact. Linearity of IRF occurs in about two-thirds of the significant regions except for Asian OC. ENF is an effective tool to estimate forcing changes due to reduction of surface emissions, as long as there is sufficient attention to the causes of nonlinearity in the simulations used to derive ENIRF (emission into polluted regions and emission elevation). The differences in ENIRF have important implications for policy decisions. Lower ENIRF in more polluted region like Asia means that reductions of

  20. Black carbon radiative forcing derived from AERONET measurements and models over an urban location in the southeastern Iberian Peninsula

    Science.gov (United States)

    Valenzuela, A.; Arola, A.; Antón, M.; Quirantes, A.; Alados-Arboledas, L.

    2017-07-01

    This paper provides an account of observed variations in Black carbon (BC) aerosol concentrations and their induced radiative forcing for the first time over Granada a measurement site in Southeastern Iberian Peninsula. Column-integrated BC concentrations were retrieved for the period 2005-2012. Monthly averages of BC concentrations (± one standard deviation) ranged from higher values in January and December with 4.0 ± 2.5 and 4 ± 3 mg/m2, respectively, to lower values in July and August with 1.6 ± 1.2 and 2.0 ± 0.5 mg/m2, respectively. This reduction is not only observed in the average values, but also in the median, third and first quartiles. The average BC concentration in winter (3.8 ± 0.6 mg/m2) was substantially higher than in summer (1.9 ± 0.3 mg/m2), being the eight-year average of 2.9 ± 0.9 mg/m2. The reduction in the use of fossil fuels during the economic crisis contributed significantly to reduced atmospheric loadings of BC. According to our analysis this situation persisted until 2010. BC concentration values were analyzed in terms of air mass influence using cluster analysis. BC concentrations for cluster 1 (local and regional areas) showed high correlations with air masses frequency in winter and autumn. In these seasons BC sources were related to the intense road traffic and increased BC emissions from domestic heating. High BC concentrations were found in autumn just when air mass frequencies for cluster 3 (Mediterranean region) were more elevated, suggesting that air masses coming from that area transport biomass burning particles towards Granada. BC aerosol optical properties were retrieved from BC fraction using aerosol AERONET size volume distribution and Mie theory. A radiative transfer model (SBDART) was used to estimate the aerosol radiative forcing separately for composite aerosol (total aerosols) and exclusively for BC aerosols. The mean radiative forcing for composite aerosol was + 23 ± 6 W/m2 (heating rate of + 0.21 ± 0.06 K

  1. Reevaluation of Mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data

    Directory of Open Access Journals (Sweden)

    Y. Balkanski

    2007-01-01

    Full Text Available Modelling studies and satellite retrievals do not agree on the amplitude and/or sign of the direct radiative perturbation from dust. Modelling studies have systematically overpredicted mineral dust absorption compared to estimates based upon satellite retrievals. In this paper we first point out the source of this discrepancy, which originates from the shortwave refractive index of dust used in models. The imaginary part of the refractive index retrieved from AERONET over the range 300 to 700 nm is 3 to 6 times smaller than that used previously to model dust. We attempt to constrain these refractive indices using a mineralogical database and varying the abundances of iron oxides (the main absorber in the visible. We first consider the optically active mineral constituents of dust and compute the refractive indices from internal and external mixtures of minerals with relative amounts encountered in parent soils. We then compute the radiative perturbation due to mineral aerosols for internally and externally mixed minerals for 3 different hematite contents, 0.9%, 1.5% and 2.7% by volume. These constant amounts of hematite allow bracketing the influence of dust aerosol when it is respectively an inefficient, standard and a very efficient absorber. These values represent low, central and high content of iron oxides in dust determined from the mineralogical database. Linke et al. (2006 determined independently that iron-oxides represent 1.0 to 2.5% by volume using x-Ray fluorescence on 4 different samples collected over Morocco and Egypt. Based upon values of the refractive index retrieved from AERONET, we show that the best agreement between 440 and 1020 nm occurs for mineral dust internally mixed with 1.5% volume weighted hematite. This representation of mineral dust allows us to compute, using a general circulation model, a new global estimate of mineral dust perturbation between –0.47 and –0.24 Wm−2 at the top of the atmosphere, and between

  2. The Impact of Pre-Industrial Land Use Change on Atmospheric Composition and Aerosol Radiative Forcing.

    Science.gov (United States)

    Hamilton, D. S.; Carslaw, K. S.; Spracklen, D. V.; Folberth, G.; Kaplan, J. O.; Pringle, K.; Scott, C.

    2015-12-01

    Anthropogenic land use change (LUC) has had a major impact on the climate by altering the amount of carbon stored in vegetation, changing surface albedo and modifying the levels of both biogenic and pyrogenic emissions. While previous studies of LUC have largely focused on the first two components, there has recently been a recognition that changes to aerosol and related pre-cursor gas emissions from LUC are equally important. Furthermore, it has also recently been recognised that the pre-industrial (PI) to present day (PD) radiative forcing (RF) of climate from aerosol cloud interactions (ACI) due to anthropogenic emissions is highly sensitive to the amount of natural aerosol that was present in the PI. This suggests that anthropogenic RF from ACI may be highly sensitive to land-use in the PI. There are currently two commonly used baseline reference years for the PI; 1750 and 1860. Rapid LUC occurred between 1750 and 1860, with large reductions in natural vegetation cover in Eastern Northern America, Europe, Central Russia, India and Eastern China as well as lower reductions in parts of Brazil and Africa. This LUC will have led to significant changes in biogenic and fire emissions with implications for natural aerosol concentrations and PI-to-PD RF. The focus of this study is therefore to quantify the impact of LUC between 1750 and 1860 on aerosol concentrations and PI-to-PD RF calculations from ACI. We use the UK Met Office HadGEM3-UKCA coupled-chemistry-climate model to calculate the impacts of anthropogenic emissions and anthropogenic LUC on aerosol size distributions in both 1750 and 1860. We prescribe LUC using the KK10 historical dataset of land cover change. Monoterpene emissions are coupled directly to the prescribed LUC through the JULES land surface scheme in HadGEM3. Fire emissions from LUC were calculated offline using the fire module LPJ-LMfire in the Lund-Potsdam-Jena dynamic global vegetation model. To separate out the impacts of LUC from

  3. Preclinical evaluation of acoustic radiation force impulse measurements in regions of heterogeneous elasticity

    Energy Technology Data Exchange (ETDEWEB)

    Hollerieth, Katharina; Moog, Philipp; Vo-Cong, Minh-Truc; Heemann, Uwe [Nephrology Department, Klinikum Rechts der Isar of the Technical University of Munich, Munich (Germany); Gassmann, Bernhard [Meso International GmbH, Berlin (Germany); Wagenpfeil, Stefan [Institute for Medical Biometry, Epidemiology and Medical Informatics, Saarland University, Campus Homburg (Saar), Homburg (Germany)

    2016-08-15

    The purpose of this study was to compare the reliability of ultrasound-based shear wave elastography in regions of homogeneous versus heterogeneous elasticity by using two different probes. Using acoustic radiation force impulse (ARFI) elastography, we measured the shear wave velocity (SWV) in different lesions of an elastography phantom with the convex {sub 4}C{sub 1} probe and the linear {sub 9}L{sub 4} probe. The region of interest (ROI) was positioned in such a way that it was partly filled by one of the lesions (0%, 25%, 50%, 75%, and 100%) and partly by the background of the phantom (100%, 75%, 50%, 25%, and 0%, respectively). The success rate was 98.5%. The measured value and the reference value of SWV correlated significantly (r=0.89, P<0.001). Further, a comparison of the two probes revealed that there was no statistical difference in either the mean or the variance values. However, the deviation of SWV from the reference was higher in the case of the {sub 9}L{sub 4} probe than in the case of the {sub 4}C{sub 1} probe, both overall and in measurements in which the ROI contained structures of different elasticity (P=0.021 and P=0.002). Taking into account all data, for both probes, we found that there was a greater spread and deviation of the SWV from the reference value when the ROI was positioned in structures having different elastic properties (standard deviation, 0.02±0.01 m/sec vs. 0.04±0.04 m/sec; P=0.010; deviation from the reference value, 0.21±0.12 m/sec vs. 0.38±0.27 m/sec; P=0.050). Quantitative ARFI elastography was achievable in structures of different elasticity; however, the validity and the reliability of the SWV measurements decreased in comparison to those of the measurements performed in structures of homogeneous elasticity. Therefore, a convex probe is preferred for examining heterogeneous structures.

  4. Can acoustic radiation force impulse elastography be a substitute for liver biopsy in predicting liver fibrosis?

    International Nuclear Information System (INIS)

    Jain, V.; Dixit, R.; Chowdhury, V.; Puri, A.S.; Gondal, R.

    2016-01-01

    Aim: To evaluate the clinical feasibility and accuracy of acoustic radiation force impulse (ARFI) elastography for the detection of liver fibrosis in patients with chronic viral hepatitis. Materials and methods: ARFI-based ultrasound elastography was performed in 69 patients with chronic liver disease (CLD) of viral aetiology and 36 healthy volunteers. Fifty-eight patients with CLD also underwent liver biopsy. Results: ARFI was feasible in all 36 healthy volunteers and all 69 CLD patients, while valid measurements were obtained in 65 patients (95.6%) and all healthy volunteers. The mean shear-wave velocity (SWV) in healthy volunteers was 1.12±0.2 m/s. A gradual increase in mean SWV was noted from fibrosis of Grade F0 to F6 (Ishak's score) and a high positive correlation was found between the mean SWV on ARFI and fibrosis scores at liver biopsy (rho=0.789). The difference between the mild (F1 and F2) versus significant fibrosis (F3 and F4) was also statistically significant (p<0.001). The difference in the SWV measurements obtained from consecutive groups (i.e., F1 versus F2, F2 versus F3, and F3 versus F4) was not statistically significant. Using the area under the receiver operating characteristic curve (AUROC), the best calculated cut-off SWVs for the presence of fibrosis (≥F1), significant fibrosis (≥F3), severe fibrosis (≥F4), and cirrhosis (F6) were found to be 1.207, 1.347, 1.513, and 1.92 m/s, respectively. ARFI values were significantly higher in cirrhotic patients than in other patients (p<0.001). Conclusions: ARFI elastography allows valid non-invasive evaluation of liver stiffness and may help to distinguish between no/mild fibrosis and significant fibrosis and guide management decisions. - Highlights: • Our study included healthy volunteer with 28 males and 8 females in a ratio of 3:1 with mean SWV of 1.2±0.20m/s. • A high positive correlation was found between the SWV on ARFI and fibrosis scores. • There was a significantly higher mean

  5. Meeting the Radiative Forcing Targets of the Representative Concentration Pathways with Agricultural Climate Impacts

    Science.gov (United States)

    Kyle, P.; Müller, C.; Calvin, K. V.; Thomson, A. M.

    2013-12-01

    The Representative Concentration Pathways (RCPs) have formed the basis for much of the current scientific understanding of future climate change impacts and mitigation. However, the emissions scenarios underlying the RCPs were produced by integrated assessment models that did not include impacts of future climate change on the modeled evolution of the agricultural and energy systems. Given the prominent role of bioenergy in greenhouse gas emissions mitigation, and given the importance of land-use-related emissions in determining future atmospheric CO2 concentrations, it is possible that agricultural climate impacts may cause significant changes to the means and costs of mitigating greenhouse gas emissions. This study builds on several international modeling exercises aimed at improving understanding of climate change impacts--CMIP-5 and ISI-MIP--that have generated global gridded climate impacts on yields of major agricultural crops in each of the four RCPs. We use the climate outcomes from the HadGEM2-ES climate model, and the agricultural yield outcomes from the LPJmL crop growth model to inform inputs to the GCAM integrated assessment model, allowing analysis of how agricultural climate impacts may affect the long-term global and regional strategies for achieving the greenhouse gas concentration pathways of the RCPs. Our results indicate that for this combination of models and emissions scenarios, strongly negative climate impacts on several major commodity classes--prominently cereals and oil seeds, and particularly in the high-radiative-forcing RCPs--lead to a long-term increase in cropland and therefore land-use-related CO2 emissions. All else equal, this increases the emissions mitigation burden on the rest of the system, and therefore increases total net costs of emissions mitigation. However, the future climate change impacts on C4 bioenergy crops tend to be positive, limiting the shock of agricultural climate impacts on the modeled energy supply and

  6. Current Status and Recommendations for the Future of Research, Teaching, and Testing in the Biological Sciences of Radiation Oncology: Report of the American Society for Radiation Oncology Cancer Biology/Radiation Biology Task Force, Executive Summary

    Energy Technology Data Exchange (ETDEWEB)

    Wallner, Paul E., E-mail: pwallner@theabr.org [21st Century Oncology, LLC, and the American Board of Radiology, Bethesda, Maryland (United States); Anscher, Mitchell S. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Barker, Christopher A. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Bassetti, Michael [Department of Human Oncology, University of Wisconsin Carbone Cancer Center, Madison, Wisconsin (United States); Bristow, Robert G. [Departments of Radiation Oncology and Medical Biophysics, Princess Margaret Cancer Center/University of Toronto, Toronto, Ontario (Canada); Cha, Yong I. [Department of Radiation Oncology, Norton Cancer Center, Louisville, Kentucky (United States); Dicker, Adam P. [Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania (United States); Formenti, Silvia C. [Department of Radiation Oncology, New York University, New York, New York (United States); Graves, Edward E. [Departments of Radiation Oncology and Radiology, Stanford University, Stanford, California (United States); Hahn, Stephen M. [Department of Radiation Oncology, University of Pennsylvania (United States); Hei, Tom K. [Center for Radiation Research, Columbia University, New York, New York (United States); Kimmelman, Alec C. [Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts (United States); Kirsch, David G. [Department of Radiation Oncology, Duke University, Durham, North Carolina (United States); Kozak, Kevin R. [Department of Human Oncology, University of Wisconsin (United States); Lawrence, Theodore S. [Department of Radiation Oncology, University of Michigan (United States); Marples, Brian [Department of Radiation Oncology, Oakland University, Oakland, California (United States); and others

    2014-01-01

    In early 2011, a dialogue was initiated within the Board of Directors (BOD) of the American Society for Radiation Oncology (ASTRO) regarding the future of the basic sciences of the specialty, primarily focused on the current state and potential future direction of basic research within radiation oncology. After consideration of the complexity of the issues involved and the precise nature of the undertaking, in August 2011, the BOD empanelled a Cancer Biology/Radiation Biology Task Force (TF). The TF was charged with developing an accurate snapshot of the current state of basic (preclinical) research in radiation oncology from the perspective of relevance to the modern clinical practice of radiation oncology as well as the education of our trainees and attending physicians in the biological sciences. The TF was further charged with making suggestions as to critical areas of biological basic research investigation that might be most likely to maintain and build further the scientific foundation and vitality of radiation oncology as an independent and vibrant medical specialty. It was not within the scope of service of the TF to consider the quality of ongoing research efforts within the broader radiation oncology space, to presume to consider their future potential, or to discourage in any way the investigators committed to areas of interest other than those targeted. The TF charge specifically precluded consideration of research issues related to technology, physics, or clinical investigations. This document represents an Executive Summary of the Task Force report.

  7. A transitioning Arctic surface energy budget: the impacts of solar zenith angle, surface albedo and cloud radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Sedlar, Joseph; Tjernstroem, Michael; Leck, Caroline [Stockholm University, Department of Meteorology, Stockholm (Sweden); Mauritsen, Thorsten [Max-Planck-Institute for Meteorology, Hamburg (Germany); Shupe, Matthew D.; Persson, P.O.G. [University of Colorado, NOAA-ESRL-PSD, Boulder, CO (United States); Brooks, Ian M.; Birch, Cathryn E. [University of Leeds, School of Earth and Environment, Leeds (United Kingdom); Sirevaag, Anders [University of Bergen, Bjerknes Center for Climate Research, Bergen (Norway); Nicolaus, Marcel [Norwegian Polar Institute, Tromsoe (Norway); Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany)

    2011-10-15

    Snow surface and sea-ice energy budgets were measured near 87.5 N during the Arctic Summer Cloud Ocean Study (ASCOS), from August to early September 2008. Surface temperature indicated four distinct temperature regimes, characterized by varying cloud, thermodynamic and solar properties. An initial warm, melt-season regime was interrupted by a 3-day cold regime where temperatures dropped from near zero to -7 C. Subsequently mean energy budget residuals remained small and near zero for 1 week until once again temperatures dropped rapidly and the energy budget residuals became negative. Energy budget transitions were dominated by the net radiative fluxes, largely controlled by the cloudiness. Variable heat, moisture and cloud distributions were associated with changing air-masses. Surface cloud radiative forcing, the net radiative effect of clouds on the surface relative to clear skies, is estimated. Shortwave cloud forcing ranged between -50 W m{sup -2} and zero and varied significantly with surface albedo, solar zenith angle and cloud liquid water. Longwave cloud forcing was larger and generally ranged between 65 and 85 W m{sup -2}, except when the cloud fraction was tenuous or contained little liquid water; thus the net effect of the clouds was to warm the surface. Both cold periods occurred under tenuous, or altogether absent, low-level clouds containing little liquid water, effectively reducing the cloud greenhouse effect. Freeze-up progression was enhanced by a combination of increasing solar zenith angles and surface albedo, while inhibited by a large, positive surface cloud forcing until a new air-mass with considerably less cloudiness advected over the experiment area. (orig.)

  8. Tooth extraction by orthodontic force after radiation therapy: report of case

    Energy Technology Data Exchange (ETDEWEB)

    Rodu, B.; Filler, S.J.; Woodfin, G.K.

    1985-12-01

    This report presents a therapeutic approach to orthodontic tooth extraction in a patient at high risk for the development of osteoradionecrosis with conventional techniques. The rationale for this procedure is discussed in detail, combining principles of radiation biology, clinical radiation therapy, and biomechanics of tooth movement.

  9. Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula

    KAUST Repository

    Osipov, Sergey; Stenchikov, Georgiy L.; Brindley, H.; Banks, J.

    2015-01-01

    In this study we attempted to better quantify radiative effects of dust over the Arabian Peninsula and their dependence on input parameters. For this purpose we have developed a stand-alone column radiation transport model coupled with the Mie, T

  10. Tooth extraction by orthodontic force after radiation therapy: report of case

    International Nuclear Information System (INIS)

    Rodu, B.; Filler, S.J.; Woodfin, G.K.

    1985-01-01

    This report presents a therapeutic approach to orthodontic tooth extraction in a patient at high risk for the development of osteoradionecrosis with conventional techniques. The rationale for this procedure is discussed in detail, combining principles of radiation biology, clinical radiation therapy, and biomechanics of tooth movement

  11. Acoustic radiation force on an air bubble and soft fluid spheres in ideal liquids: example of a high-order Bessel beam of quasi-standing waves.

    Science.gov (United States)

    Mitri, F G

    2009-04-01

    The partial wave series for the scattering of a high-order Bessel beam (HOBB) of acoustic quasi-standing waves by an air bubble and fluid spheres immersed in water and centered on the axis of the beam is applied to the calculation of the acoustic radiation force. A HOBB refers to a type of beam having an axial amplitude null and an azimuthal phase gradient. Radiation force examples obtained through numerical evaluation of the radiation force function are computed for an air bubble, a hexane, a red blood and mercury fluid spheres in water. The examples were selected to illustrate conditions having progressive, standing and quasi-standing waves with appropriate selection of the waves' amplitude ratio. An especially noteworthy result is the lack of a specific vibrational mode contribution to the radiation force determined by appropriate selection of the HOBB parameters.

  12. Snow driven Radiative Forcing in High Latitude Areas of Disturbance Using Higher Resolution Albedo Products from Landsat and Sentinel-2

    Science.gov (United States)

    Erb, A.; Li, Z.; Schaaf, C.; Wang, Z.; Rogers, B. M.

    2017-12-01

    Land surface albedo plays an important role in the surface energy budget and radiative forcing by determining the proportion of absorbed incoming solar radiation available to drive photosynthesis and surface heating. In Arctic regions, albedo is particularly sensitive to land cover and land use change (LCLUC) and modeling efforts have shown it to be the primary driver of effective radiative forcing from the biogeophysical effects of LCLUC. In boreal forests, the effects of these changes are complicated during snow covered periods when newly exposed, highly reflective snow can serve as the primary driver of radiative forcing. In Arctic biomes disturbance scars from fire, pest and harvest can remain in the landscape for long periods of time. As such, understanding the magnitude and persistence of these disturbances, especially in the shoulder seasons, is critical. The Landsat and Sentinel-2 Albedo Products couple 30m and 20m surface reflectances with concurrent 500m BRDF Products from the MODerate resolution Imaging Spectroradiometer (MODIS). The 12 bit radiometric fidelity of Sentinel-2 and Landsat-8 allow for the inclusion of high-quality, unsaturated albedo calculations over snow covered surfaces at scales more compatible with fragmented landscapes. Recent work on the early spring albedo of fire scars has illustrated significant post-fire spatial heterogeneity of burn severity at the landscape scale and highlights the need for a finer spatial resolution albedo record. The increased temporal resolution provided by multiple satellite instruments also allows for a better understanding of albedo dynamics during the dynamic shoulder seasons and in historically difficult high latitude locations where persistent cloud cover limits high quality retrievals. Here we present how changes in the early spring albedo of recent boreal forest disturbance in Alaska and central Canada affects landscape-scale radiative forcing. We take advantage of the long historical Landsat record

  13. Aerosols, Chemistry, and Radiative Forcing: A 3-D Model Analysis of Satellite and ACE-Asia data (ACMAP)

    Science.gov (United States)

    Chin, Mian; Ginoux, Paul; Torres, Omar; Zhao, Xue-Peng

    2005-01-01

    We propose a research project to incorporate a global 3-D model and satellite data into the multi-national Aerosol Characterization Experiment-Asia (ACE-Asia) mission. Our objectives are (1) to understand the physical, chemical, and optical properties of aerosols and the processes that control those properties over the Asian-Pacific region, (2) to investigate the interaction between aerosols and tropospheric chemistry, and (3) to determine the aerosol radiative forcing over the Asia-Pacific region. We will use the Georgia TecWGoddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model to link satellite observations and the ACE-Asia measurements. First, we will use the GOCART model to simulate aerosols and related species, and evaluate the model with satellite and in-situ observations. Second, the model generated aerosol vertical profiles and compositions will be used to validate the satellite products; and the satellite data will be used for during- and post- mission analysis. Third, we will use the model to analyze and interpret both satellite and ACE- Asia field campaign data and investigate the aerosol-chemistry interactions. Finally, we will calculate aerosol radiative forcing over the Asian-Pacific region, and assess the influence of Asian pollution in the global atmosphere. We propose a research project to incorporate a global 3-D model and satellite data into

  14. GIS-based technology for marine geohazards in LW3-1 Gas Field of the South China Sea

    Science.gov (United States)

    Su, Tianyun; Liu, Lejun; Li, Xishuang; Hu, Guanghai; Liu, Haixing; Zhou, Lin

    2013-04-01

    been carried out with ships and AUV to collect multidisciplinary and massive submarine data such as multi-beam bathymetric data, sidescan sonar images, shallow-bottom profiling images, high-resolution multi-channel seismic data and boring test data. In order to make good use of these precious data, GIS technology is used in our research. Data model is designed to depict the structure, organization and relationship between multi disciplinary submarine data. With these data models, database is established to manage and share the attribute and spatial data effectively. The spatial datasets, such as contours, TIN models, DEM models, etc., can be generated. Some submarine characteristics, such as slope, aspects, curvature, landslide volume, etc., can be calculated and extracted with spatial analysis tools. The thematic map can be produced easily based on database and generated spatial dataset. Through thematic map, the multidisciplinary data spatial relationship can be easily established and provide helpful information for regional submarine geohazards identification, assessments and prediction. The produced thematic map of the LW3-1 Gas Field, reveal the strike of the seafloor topography to be NE to SW. Five geomorphological zones have been divided, which include the outer continental shelf margin zone with sand waves and mega-ripples, the continental slope zone with coral reefs and sand waves, the continental slope zone with a monocline shape, the continental slope zone with fault terraces and the continental slope zone with turbidity current deposits.

  15. The sensitivity of tropical convective precipitation to the direct radiative forcings of black carbon aerosols emitted from major regions

    Directory of Open Access Journals (Sweden)

    C. Wang

    2009-10-01

    Full Text Available Previous works have suggested that the direct radiative forcing (DRF of black carbon (BC aerosols are able to force a significant change in tropical convective precipitation ranging from the Pacific and Indian Ocean to the Atlantic Ocean. In this in-depth analysis, the sensitivity of this modeled effect of BC on tropical convective precipitation to the emissions of BC from 5 major regions of the world has been examined. In a zonal mean base, the effect of BC on tropical convective precipitation is a result of a displacement of ITCZ toward the forcing (warming hemisphere. However, a substantial difference exists in this effect associated with BC over different continents. The BC effect on convective precipitation over the tropical Pacific Ocean is found to be most sensitive to the emissions from Central and North America due to a persistent presence of BC aerosols from these two regions in the lowermost troposphere over the Eastern Pacific. The BC effect over the tropical Indian and Atlantic Ocean is most sensitive to the emissions from South as well as East Asia and Africa, respectively. Interestingly, the summation of these individual effects associated with emissions from various regions mostly exceeds their actual combined effect as shown in the model run driven by the global BC emissions, so that they must offset each other in certain locations and a nonlinearity of this type of effect is thus defined. It is known that anthropogenic aerosols contain many scattering-dominant constituents that might exert an effect opposite to that of absorbing BC. The combined aerosol forcing is thus likely differing from the BC-only one. Nevertheless, this study along with others of its kind that isolates the DRF of BC from other forcings provides an insight of the potentially important climate response to anthropogenic forcings particularly related to the unique particulate solar absorption.

  16. Reductions in soil surface albedo as a function of biochar application rate: implications for global radiative forcing

    International Nuclear Information System (INIS)

    Verheijen, Frank G A; Bastos, Ana Catarina; Keizer, Jan Jacob; Jeffery, Simon; Van der Velde, Marijn; Penížek, Vít; Beland, Martin

    2013-01-01

    Biochar can be defined as pyrolysed (charred) biomass produced for application to soils with the aim of mitigating global climate change while improving soil functions. Sustainable biochar application to soils has been estimated to reduce global greenhouse gas emissions by 71–130 Pg CO 2 -C e over 100 years, indicating an important potential to mitigate climate change. However, these estimates ignored changes in soil surface reflection by the application of dark-coloured biochar. Through a laboratory experiment we show a strong tendency for soil surface albedo to decrease as a power decay function with increasing biochar application rate, depending on soil moisture content, biochar application method and land use. Surface application of biochar resulted in strong reductions in soil surface albedo even at relatively low application rates. As a first assessment of the implications for climate change mitigation of these biochar–albedo relationships, we applied a first order global energy balance model to compare negative radiative forcings (from avoided CO 2 emissions) with positive radiative forcings (from reduced soil surface albedos). For a global-scale biochar application equivalent to 120 t ha −1 , we obtained reductions in negative radiative forcings of 5 and 11% for croplands and 11 and 23% for grasslands, when incorporating biochar into the topsoil or applying it to the soil surface, respectively. For a lower global biochar application rate (equivalent to 10 t ha −1 ), these reductions amounted to 13 and 44% for croplands and 28 and 94% for grasslands. Thus, our findings revealed the importance of including changes in soil surface albedo in studies assessing the net climate change mitigation potential of biochar, and we discuss the urgent need for field studies and more detailed spatiotemporal modelling. (letter)

  17. Acoustic Radiation Force Impulse Quantification in the Evaluation of Thyroid Elasticity in Pediatric Patients With Hashimoto Thyroiditis.

    Science.gov (United States)

    Yucel, Serap; Ceyhan Bilgici, Meltem; Kara, Cengiz; Can Yilmaz, Gulay; Aydin, H Murat; Elmali, Muzaffer; Tomak, Leman; Saglam, Dilek

    2018-05-01

    To evaluate the parenchymal elasticity of the thyroid gland with acoustic radiation force impulse imaging in pediatric patients with Hashimoto thyroiditis and to compare it with healthy volunteers. Twenty-six patients with Hashimoto thyroiditis and 26 healthy volunteers between 6 and 17 years were included. The shear wave velocity (SWV) values of both thyroid lobes in both groups were evaluated. The age and sex characteristics of the controls and patients with Hashimoto thyroiditis were similar. The SWV of the thyroid gland in patients with Hashimoto thyroiditis (mean ± SD, 1.67 ± 0.63 m/s) was significantly higher than that in the control group (1.30 ± 0.13 m/s; P thyroid lobes in both groups. A receiver operating characteristic curve analyses showed an optimal cutoff value of 1.41 m/s, with 73.1% sensitivity, 80.8% specificity, a 79.2 % positive predictive value, and a 75.0% negative predictive value (area under the curve, 0.806; P Hashimoto thyroiditis, there was a positive correlation between the SWV values versus anti-thyroperoxidase (Pearson r = 0.46; P = .038). There were no correlations between age, body mass index, thyroid function test results, and anti-thyroglobulin values and versus SWV values. Also, no significant differences were seen between the groups for gland size, gland vascularity, and l-thyroxine treatment. Acoustic radiation force impulse elastography showed a significant difference in the stiffness of the thyroid gland between children with Hashimoto thyroiditis and the healthy group. Using acoustic radiation force impulse elastography immediately after a standard ultrasound evaluation may predict chronic autoimmune thyroiditis. © 2017 by the American Institute of Ultrasound in Medicine.

  18. MO-FG-BRB-02: Uniform Access to Radiation Therapy by 2035: Global Task Force on Radiotherapy for Cancer Control

    International Nuclear Information System (INIS)

    Jaffray, D.

    2015-01-01

    The global burden of cancer is growing rapidly with an estimated 15 million new cases per year worldwide in 2015, growing to 19 million by 2025 and 24 million by 2035. The largest component of this growth will occur in low-to-middle income countries (LMICs). About half of these cases will require radiation treatment. The gap for available cancer treatment, including radiation therapy, between high-income countries (HICs) and LMICs is enormous. Accurate data and quantitative models to project the needs and the benefits of cancer treatment are a critical first step in closing the large cancer divide between LMICs and HICs. In this context, the Union for International Cancer Control (UICC) has developed a Global Task Force on Radiotherapy for Cancer Control (GTFRCC) with a charge to answer the question as to what it will take to close the gap between what exists today and reasonable access to radiation therapy globally by 2035 and what the potential clinical and economic benefits are for doing this. The Task Force has determined the projections of cancer incidence and the infrastructure required to provide access to radiation therapy globally. Furthermore it has shown that appropriate investment not only yields improved clinical outcomes for millions of patients but that it also provides an overall economic gain throughout all the income settings where this investment is made. This symposium will summarize the facets associated with this global cancer challenge by reviewing the cancer burden, looking at the requirements for radiation therapy, reviewing the benefits of providing such therapy both from a clinical and economic perspective and finally by looking at what approaches can be used to aid in the alleviation of this global cancer challenge. The speakers are world renowned experts in global public health issues (R. Atun), medical physics (D. Jaffray) and radiation oncology (N. Coleman). Learning Objectives: To describe the global cancer challenge and the

  19. MO-FG-BRB-02: Uniform Access to Radiation Therapy by 2035: Global Task Force on Radiotherapy for Cancer Control

    Energy Technology Data Exchange (ETDEWEB)

    Jaffray, D. [Princess Margaret Cancer Centre (Canada)

    2015-06-15

    The global burden of cancer is growing rapidly with an estimated 15 million new cases per year worldwide in 2015, growing to 19 million by 2025 and 24 million by 2035. The largest component of this growth will occur in low-to-middle income countries (LMICs). About half of these cases will require radiation treatment. The gap for available cancer treatment, including radiation therapy, between high-income countries (HICs) and LMICs is enormous. Accurate data and quantitative models to project the needs and the benefits of cancer treatment are a critical first step in closing the large cancer divide between LMICs and HICs. In this context, the Union for International Cancer Control (UICC) has developed a Global Task Force on Radiotherapy for Cancer Control (GTFRCC) with a charge to answer the question as to what it will take to close the gap between what exists today and reasonable access to radiation therapy globally by 2035 and what the potential clinical and economic benefits are for doing this. The Task Force has determined the projections of cancer incidence and the infrastructure required to provide access to radiation therapy globally. Furthermore it has shown that appropriate investment not only yields improved clinical outcomes for millions of patients but that it also provides an overall economic gain throughout all the income settings where this investment is made. This symposium will summarize the facets associated with this global cancer challenge by reviewing the cancer burden, looking at the requirements for radiation therapy, reviewing the benefits of providing such therapy both from a clinical and economic perspective and finally by looking at what approaches can be used to aid in the alleviation of this global cancer challenge. The speakers are world renowned experts in global public health issues (R. Atun), medical physics (D. Jaffray) and radiation oncology (N. Coleman). Learning Objectives: To describe the global cancer challenge and the

  20. Axial and transverse acoustic radiation forces on a fluid sphere placed arbitrarily in Bessel beam standing wave tweezers

    International Nuclear Information System (INIS)

    Mitri, F.G.

    2014-01-01

    The axial and transverse radiation forces on a fluid sphere placed arbitrarily in the acoustical field of Bessel beams of standing waves are evaluated. The three-dimensional components of the time-averaged force are expressed in terms of the beam-shape coefficients of the incident field and the scattering coefficients of the fluid sphere using a partial-wave expansion (PWE) method. Examples are chosen for which the standing wave field is composed of either a zero-order (non-vortex) Bessel beam, or a first-order Bessel vortex beam. It is shown here, that both transverse and axial forces can push or pull the fluid sphere to an equilibrium position depending on the chosen size parameter ka (where k is the wave-number and a the sphere’s radius). The corresponding results are of particular importance in biophysical applications for the design of lab-on-chip devices operating with Bessel beams standing wave tweezers. Moreover, potential investigations in acoustic levitation and related applications in particle rotation in a vortex beam may benefit from the results of this study. -- Highlights: •The axial and transverse forces on a fluid sphere in acoustical Bessel beams tweezers are evaluated. •The attraction or repulsion to an equilibrium position in the standing wave field is examined. •Potential applications are in particle manipulation using standing waves

  1. Axial and transverse acoustic radiation forces on a fluid sphere placed arbitrarily in Bessel beam standing wave tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Mitri, F.G., E-mail: mitri@chevron.com

    2014-03-15

    The axial and transverse radiation forces on a fluid sphere placed arbitrarily in the acoustical field of Bessel beams of standing waves are evaluated. The three-dimensional components of the time-averaged force are expressed in terms of the beam-shape coefficients of the incident field and the scattering coefficients of the fluid sphere using a partial-wave expansion (PWE) method. Examples are chosen for which the standing wave field is composed of either a zero-order (non-vortex) Bessel beam, or a first-order Bessel vortex beam. It is shown here, that both transverse and axial forces can push or pull the fluid sphere to an equilibrium position depending on the chosen size parameter ka (where k is the wave-number and a the sphere’s radius). The corresponding results are of particular importance in biophysical applications for the design of lab-on-chip devices operating with Bessel beams standing wave tweezers. Moreover, potential investigations in acoustic levitation and related applications in particle rotation in a vortex beam may benefit from the results of this study. -- Highlights: •The axial and transverse forces on a fluid sphere in acoustical Bessel beams tweezers are evaluated. •The attraction or repulsion to an equilibrium position in the standing wave field is examined. •Potential applications are in particle manipulation using standing waves.

  2. Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

    Directory of Open Access Journals (Sweden)

    Shilei Liu

    2017-07-01

    Full Text Available Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF and acoustic streaming (AS. In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV. Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning.

  3. Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

    Science.gov (United States)

    Yang, Yanye; Ni, Zhengyang; Guo, Xiasheng; Luo, Linjiao; Tu, Juan; Zhang, Dong

    2017-01-01

    Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF) and acoustic streaming (AS). In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV). Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning. PMID:28753955

  4. Structural analysis of radiation-induced chromosome aberrations by atomic force microscope (AFM) before and after Giemsa staining

    International Nuclear Information System (INIS)

    Murakami, M.; Kanda, R.; Minamihisamatsu, M.; Hayata, I.

    2003-01-01

    Full text: We have studied structures of chromosome aberration induced by ionizing radiation by an atomic force microscope (AFM). The AFM could visualize the fine structure of chromosomes on Giemsa stained or unstained samples, although it was difficult to visualize unstained chromosomes by light microscope. The height data of chromosomes obtained by AFM provided useful information to describe detailed structure of chromatid gaps induced by heavy ion irradiation. A fibrous structure was observed on the unstained chromosome and these structures were considered to be the 30nm fibers on the chromosome. These types of structures were observed in the gaps as well as on surface of the chromosome. Further more, other types of chromosome aberration induced by ionizing radiation visualized by AFM will be presented

  5. Non-Equilibrium Thermodynamic Analysis of Double Diffusive, Nanofluid Forced Convection in Catalytic Microreactors with Radiation Effects

    Directory of Open Access Journals (Sweden)

    Lilian Govone

    2017-12-01

    Full Text Available This paper presents a theoretical investigation of the second law performance of double diffusive forced convection in microreactors with the inclusion of nanofluid and radiation effects. The investigated microreactors consist of a single microchannel, fully filled by a porous medium. The transport of heat and mass are analysed by including the thick walls and a first order, catalytic chemical reaction on the internal surfaces of the microchannel. Two sets of thermal boundary conditions are considered on the external surfaces of the microchannel; (1 constant temperature and (2 constant heat flux boundary condition on the lower wall and convective boundary condition on the upper wall. The local thermal non-equilibrium approach is taken to thermally analyse the porous section of the system. The mass dispersion equation is coupled with the transport of heat in the nanofluid flow through consideration of Soret effect. The problem is analytically solved and illustrations of the temperature fields, Nusselt number, total entropy generation rate and performance evaluation criterion (PEC are provided. It is shown that the radiation effect tends to modify the thermal behaviour within the porous section of the system. The radiation parameter also reduces the overall temperature of the system. It is further demonstrated that, expectedly, the nanoparticles reduce the temperature of the system and increase the Nusselt number. The total entropy generation rate and consequently PEC shows a strong relation with radiation parameter and volumetric concentration of nanoparticles.

  6. Casimir Forces and Quantum Friction from Ginzburg Radiation in Atomic Bose-Einstein Condensates.

    Science.gov (United States)

    Marino, Jamir; Recati, Alessio; Carusotto, Iacopo

    2017-01-27

    We theoretically propose an experimentally viable scheme to use an impurity atom in an atomic Bose-Einstein condensate, in order to realize condensed-matter analogs of quantum vacuum effects. In a suitable atomic level configuration, the collisional interaction between the impurity atom and the density fluctuations in the condensate can be tailored to closely reproduce the electric-dipole coupling of quantum electrodynamics. By virtue of this analogy, we recover and extend the paradigm of electromagnetic vacuum forces to the domain of cold atoms, showing in particular the emergence, at supersonic atomic speeds, of a novel power-law scaling of the Casimir force felt by the atomic impurity, as well as the occurrence of a quantum frictional force, accompanied by the Ginzburg emission of Bogoliubov quanta. Observable consequences of these quantum vacuum effects in realistic spectroscopic experiments are discussed.

  7. Dust radiative forcing in snow of the Upper Colorado River Basin: 1. A 6 year record of energy balance, radiation, and dust concentrations

    Science.gov (United States)

    Painter, Thomas H.; Skiles, S. Mckenzie; Deems, Jeffrey S.; Bryant, Ann C.; Landry, Christopher C.

    2012-07-01

    Dust in snow accelerates snowmelt through its direct reduction of snow albedo and its further indirect reduction of albedo by accelerating the growth of snow grains. Since the westward expansion of the United States that began in the mid-19th century, the mountain snow cover of the Colorado River Basin has been subject to five-fold greater dust loading, largely from the Colorado Plateau and Great Basin. Radiative forcing of snowmelt by dust is not captured by conventional micrometeorological measurements, and must be monitored by a more comprehensive suite of radiation instruments. Here we present a 6 year record of energy balance and detailed radiation measurements in the Senator Beck Basin Study Area, San Juan Mountains, Colorado, USA. Data include broadband irradiance, filtered irradiance, broadband reflected flux, filtered reflected flux, broadband and visible albedo, longwave irradiance, wind speed, relative humidity, and air temperatures. The gradient of the snow surface is monitored weekly and used to correct albedo measurements for geometric effects. The snow is sampled weekly for dust concentrations in plots immediately adjacent to each tower over the melt season. Broadband albedo in the last weeks of snow cover ranged from 0.33 to 0.55 across the 6 years and two sites. Total end of year dust concentration in the top 3 cm of the snow column ranged from 0.23 mg g-1 to 4.16 mg g-1. These measurements enable monitoring and modeling of dust and climate-driven snowmelt forcings in the Upper Colorado River Basin.

  8. Behavior of adhesion forces of silicone adhesive sealants and mastic butyl under the influence of ionizing radiation

    International Nuclear Information System (INIS)

    Costa, Wanderley da

    2012-01-01

    Adhesives are products that can keep materials together by bonds between the surfaces. Sealants are products that can keep filled a space between two surfaces, through a barrier that is configured as a 'bridge' between the two surfaces. The mastic is a product made of a mixture of substances with the primary butyl polymer, with the consistency of a mass not dried that can be used as a sealant. The polysiloxane, also known as silicone are the most important synthetic polymers with inorganic structure, and are matrices of silicone adhesive sealants. To demonstrate the behavior of the adhesive forces of these products under different conditions, we used five different techniques. These products were subjected to two different conditions to verify the behavior of adhesion, one at the environmental condition and another under the ionizing radiation. The results showed not only differences between products (silicone and mastic), but also that the adhesive forces have different behaviors under the conditions which the samples were subjected. With this was reached the goal of this study that aspired show the differences between the mastic and silicone, this last one is often considered - erroneously - the same as mastic. Thus it was proven that: 1. silicone can be regarded as an adhesive and a sealant at ambient conditions, 2. mastic improves substantially adhesion in an environment of ionizing radiation and this property can be an excellent alternative to the adhesive market. (author)

  9. Future Climate Impacts of Direct Radiative Forcing Anthropogenic Aerosols, Tropospheric Ozone, and Long-lived Greenhouse Gases

    Science.gov (United States)

    Chen, Wei-Ting; Liao, Hong; Seinfeld, John H.

    2007-01-01

    Long-lived greenhouse gases (GHGs) are the most important driver of climate change over the next century. Aerosols and tropospheric ozone (O3) are expected to induce significant perturbations to the GHG-forced climate. To distinguish the equilibrium climate responses to changes in direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and GHG between present day and year 2100, four 80-year equilibrium climates are simulated using a unified tropospheric chemistry-aerosol model within the Goddard Institute for Space Studies (GISS) general circulation model (GCM) 110. Concentrations of sulfate, nitrate, primary organic (POA) carbon, secondary organic (SOA) carbon, black carbon (BC) aerosols, and tropospheric ozone for present day and year 2100 are obtained a priori by coupled chemistry-aerosol GCM simulations, with emissions of aerosols, ozone, and precursors based on the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenario (SRES) A2. Changing anthropogenic aerosols, tropospheric ozone, and GHG from present day to year 2100 is predicted to perturb the global annual mean radiative forcing by +0.18 (considering aerosol direct effects only), +0.65, and +6.54 W m(sup -2) at the tropopause, and to induce an equilibrium global annual mean surface temperature change of +0.14, +0.32, and +5.31 K, respectively, with the largest temperature response occurring at northern high latitudes. Anthropogenic aerosols, through their direct effect, are predicted to alter the Hadley circulation owing to an increasing interhemispheric temperature gradient, leading to changes in tropical precipitation. When changes in both aerosols and tropospheric ozone are considered, the predicted patterns of change in global circulation and the hydrological cycle are similar to those induced by aerosols alone. GHG-induced climate changes, such as amplified warming over high latitudes, weakened Hadley circulation, and increasing precipitation over the

  10. A Synthetical Estimation of Northern Hemisphere Sea-ice Albedo Radiative Forcing and Feedback between 1982 and 2009

    Science.gov (United States)

    Cao, Y.

    2014-12-01

    The decreasing surface albedo caused by continously vanishing sea ice over the Arctic plays a very important role in Arctic warming amplification. However, the quantification of the change of radiative forcing at top of atmosphere (TOA) introduced by the decreasing sea ice albedo and its generated feedback to the climate remain uncertain. Two recent representative studies showed a large difference with each other: Flanner et al. (2011) used a method of synthesis of surface albedo and radiative kernels and found that the change of sea ice radiative forcing (ΔSIRF) in Northern Hemisphere (NH) from 1979 to 2008 was 0.22 (0.15 - 0.32) W m-2, and the corresponding sea ice albedo feedback (SIAF) over NH was 0.28 (0.19 - 0.41) W m-2 K-1; while Pistone et al. (2014) directly used the observed planetary albedo to estimate the NH ΔSIRF and SIAF from 1979 to 2011 and draw a NH ΔSIRF of 0.43 ± 0.07 W m-2, which was nearly twice as larger as Flanner's result, and the estimated global SIAF was 0.31 ± 0.04 W m-2 K-1. Motivated by reconciling the difference between these two studies and obtaining a more accurate qualification of the NH ΔSIRF, we used a newly released satellite-retrieved surface albedo product CLARA-A1 and made an attempt in two steps: Firstly, based on synthesising the surface albedo and raditive kernels, we calcualted the ΔSIRF from 1982 to 2009 was 0.20 ± 0.05 W m-2, and the NH SIAF was 0.25 W m-2 K-1; After comparing with TOA observed radiative flux, we found it's quite likely the kernel methods yield an underestimation for the all-sky ΔSIRF. Then, we tried to use TOA observed broadband radiative flux to adjust the estimation with kernels. After an adjustment, the NH all-sky ΔSIRF was 0.34 ± 0.09 W m-2, and the corresponding SIAF was 0.43 W m-2 K-1 over NH and 0.31 W m-2 K-1 over the entire globe.

  11. Zonal Aerosol Direct and Indirect Radiative Forcing using Combined CALIOP, CERES, CloudSat, and CERES Data

    Science.gov (United States)

    Miller, W. F.; Kato, S.; Rose, F. G.; Sun-Mack, S.

    2009-12-01

    Under the NASA Energy and Water Cycle System (NEWS) program, cloud and aerosol properties derived from CALIPSO, CloudSat, and MODIS data then matched to the CERES footprint are used for irradiance profile computations. Irradiance profiles are included in the publicly available product, CCCM. In addition to the MODIS and CALIPSO generated aerosol, aerosol optical thickness is calculated over ocean by processing MODIS radiance through the Stowe-Ignatov algorithm. The CERES cloud mask and properties algorithm are use with MODIS radiance to provide additional cloud information to accompany the actively sensed data. The passively sensed data is the only input to the standard CERES radiative flux products. The combined information is used as input to the NASA Langley Fu-Liou radiative transfer model to determine vertical profiles and Top of Atmosphere shortwave and longwave flux for pristine, all-sky, and aerosol conditions for the special data product. In this study, the three sources of aerosol optical thickness will be compared directly and their influence on the calculated and measured TOA fluxes. Earlier studies indicate that the largest uncertainty in estimating direct aerosol forcing using aerosol optical thickness derived from passive sensors is caused by cloud contamination. With collocated CALIPSO data, we are able to estimate frequency of occurrence of cloud contamination, effect on the aerosol optical thickness and direct radiative effect estimates.

  12. Variability of radiatively forced diurnal cycle of intense convection in the tropical west pacific

    Energy Technology Data Exchange (ETDEWEB)

    Gray, W.M.; Sheaffer, J.D.; Thorson, W.B. [Colorado State Univ., Fort Collins, CO (United States)

    1996-04-01

    Strong differences occur in daytime versus nighttime (DVN) net radiative cooling in clear versus cloudy areas of the tropical atmosphere. Daytime average cooling is approximately -0.7{degrees}C/day, whereas nighttime net tropospheric cooling rates are about -1.5{degrees}C/day, an approximately two-to-one difference. The comparatively strong nocturnal cooling in clear areas gives rise to a diurnally varying vertical circulation and horizontal convergence cycle. Various manifestations of this cyclic process include the observed early morning heavy rainfall maxima over the tropical oceans. The radiatively driven DVN circulation appears to strongly modulate the resulting diurnal cycle of intense convection which creates the highest, coldest cloudiness over maritime tropical areas and is likely a fundamental mechanism governing both small and large scale dynamics over much of the tropical environment.

  13. Acoustic attraction, repulsion and radiation force cancellation on a pair of rigid particles with arbitrary cross-sections in 2D: Circular cylinders example

    Science.gov (United States)

    Mitri, F. G.

    2017-11-01

    The acoustic radiation forces arising on a pair of sound impenetrable cylindrical particles of arbitrary cross-sections are derived. Plane progressive, standing or quasi-standing waves with an arbitrary incidence angle are considered. Multiple scattering effects are described using the multipole expansion formalism and the addition theorem of cylindrical wave functions. An effective incident acoustic field on a particular object is determined, and used with the scattered field to derive closed-form analytical expressions for the radiation force vector components. The mathematical expressions for the radiation force components are exact, and have been formulated in partial-wave series expansions in cylindrical coordinates involving the angle of incidence, the reflection coefficient forming the progressive or the (quasi)standing wave field, the addition theorem, and the expansion coefficients. Numerical examples illustrate the analysis for two rigid circular cross-sections immersed in a non-viscous fluid. Computations for the dimensionless radiation force functions are performed with emphasis on varying the angle of incidence, the interparticle distance, the sizes of the particles as well as the characteristics of the incident field. Depending on the interparticle distance and angle of incidence, one of the particles yields neutrality; it experiences no force and becomes unresponsive (i.e., ;invisible;) to the linear momentum transfer of the effective incident field due to multiple scattering cancellation effects. Moreover, attractive or repulsive forces between the two particles may arise depending on the interparticle distance, the angle of incidence and size parameters of the particles. This study provides a complete analytical method and computations for the axial and transverse radiation force components in multiple acoustic scattering encompassing the cases of plane progressive, standing or quasi-standing waves of arbitrary incidence by a pair of scatterers

  14. Design of a phased array for the generation of adaptive radiation force along a path surrounding a breast lesion for dynamic ultrasound elastography imaging.

    Science.gov (United States)

    Ekeom, Didace; Hadj Henni, Anis; Cloutier, Guy

    2013-03-01

    This work demonstrates, with numerical simulations, the potential of an octagonal probe for the generation of radiation forces in a set of points following a path surrounding a breast lesion in the context of dynamic ultrasound elastography imaging. Because of the in-going wave adaptive focusing strategy, the proposed method is adapted to induce shear wave fronts to interact optimally with complex lesions. Transducer elements were based on 1-3 piezocomposite material. Three-dimensional simulations combining the finite element method and boundary element method with periodic boundary conditions in the elevation direction were used to predict acoustic wave radiation in a targeted region of interest. The coupling factor of the piezocomposite material and the radiated power of the transducer were optimized. The transducer's electrical impedance was targeted to 50 Ω. The probe was simulated by assembling the designed transducer elements to build an octagonal phased-array with 256 elements on each edge (for a total of 2048 elements). The central frequency is 4.54 MHz; simulated transducer elements are able to deliver enough power and can generate the radiation force with a relatively low level of voltage excitation. Using dynamic transmitter beamforming techniques, the radiation force along a path and resulting acoustic pattern in the breast were simulated assuming a linear isotropic medium. Magnitude and orientation of the acoustic intensity (radiation force) at any point of a generation path could be controlled for the case of an example representing a heterogeneous medium with an embedded soft mechanical inclusion.

  15. The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest-wetland landscape.

    Science.gov (United States)

    Helbig, Manuel; Chasmer, Laura E; Kljun, NatasCha; Quinton, William L; Treat, Claire C; Sonnentag, Oliver

    2017-06-01

    At the southern margin of permafrost in North America, climate change causes widespread permafrost thaw. In boreal lowlands, thawing forested permafrost peat plateaus ('forest') lead to expansion of permafrost-free wetlands ('wetland'). Expanding wetland area with saturated and warmer organic soils is expected to increase landscape methane (CH 4 ) emissions. Here, we quantify the thaw-induced increase in CH 4 emissions for a boreal forest-wetland landscape in the southern Taiga Plains, Canada, and evaluate its impact on net radiative forcing relative to potential long-term net carbon dioxide (CO 2 ) exchange. Using nested wetland and landscape eddy covariance net CH 4 flux measurements in combination with flux footprint modeling, we find that landscape CH 4 emissions increase with increasing wetland-to-forest ratio. Landscape CH 4 emissions are most sensitive to this ratio during peak emission periods, when wetland soils are up to 10 °C warmer than forest soils. The cumulative growing season (May-October) wetland CH 4 emission of ~13 g CH 4  m -2 is the dominating contribution to the landscape CH 4 emission of ~7 g CH 4  m -2 . In contrast, forest contributions to landscape CH 4 emissions appear to be negligible. The rapid wetland expansion of 0.26 ± 0.05% yr -1 in this region causes an estimated growing season increase of 0.034 ± 0.007 g CH 4  m -2  yr -1 in landscape CH 4 emissions. A long-term net CO 2 uptake of >200 g CO 2  m -2  yr -1 is required to offset the positive radiative forcing of increasing CH 4 emissions until the end of the 21st century as indicated by an atmospheric CH 4 and CO 2 concentration model. However, long-term apparent carbon accumulation rates in similar boreal forest-wetland landscapes and eddy covariance landscape net CO 2 flux measurements suggest a long-term net CO 2 uptake between 49 and 157 g CO 2  m -2  yr -1 . Thus, thaw-induced CH 4 emission increases likely exert a positive net radiative greenhouse gas

  16. Radiative forcing estimates of sulfate aerosol in coupled climate-chemistry models with emphasis on the role of the temporal variability

    Directory of Open Access Journals (Sweden)

    C. Déandreis

    2012-06-01

    Full Text Available This paper describes the impact on the sulfate aerosol radiative effects of coupling the radiative code of a global circulation model with a chemistry-aerosol module. With this coupling, temporal variations of sulfate aerosol concentrations influence the estimate of aerosol radiative impacts. Effects of this coupling have been assessed on net fluxes, radiative forcing and temperature for the direct and first indirect effects of sulfate.

    The direct effect respond almost linearly to rapid changes in concentrations whereas the first indirect effect shows a strong non-linearity. In particular, sulfate temporal variability causes a modification of the short wave net fluxes at the top of the atmosphere of +0.24 and +0.22 W m−2 for the present and preindustrial periods, respectively. This change is small compared to the value of the net flux at the top of the atmosphere (about 240 W m−2. The effect is more important in regions with low-level clouds and intermediate sulfate aerosol concentrations (from 0.1 to 0.8 μg (SO4 m−3 in our model.

    The computation of the aerosol direct radiative forcing is quite straightforward and the temporal variability has little effect on its mean value. In contrast, quantifying the first indirect radiative forcing requires tackling technical issues first. We show that the preindustrial sulfate concentrations have to be calculated with the same meteorological trajectory used for computing the present ones. If this condition is not satisfied, it introduces an error on the estimation of the first indirect radiative forcing. Solutions are proposed to assess radiative forcing properly. In the reference method, the coupling between chemistry and climate results in a global average increase of 8% in the first indirect radiative forcing. This change reaches 50% in the most sensitive regions. However, the reference method is not suited to run long climate

  17. The investigation of the light radiation caused polyethylene based materials deterioration by means of atomic force microscopy

    International Nuclear Information System (INIS)

    Sikora, A; Moroń, L; Wałecki, M; Kryla, P; Grabarek, A

    2016-01-01

    The impact of the environmental conditions on the materials used in various devices and constructions, in particular in electrotechnical applications, has an critical impact in terms of their reliability and utilization range in specific climatic conditions. Due to increasing utilitarian requirements, technological processes complexity and introducing new materials (for instance nanomaterials), advanced diagnostic techniques are desired. One of such techniques is atomic force microscopy (AFM), which allows to study the changes of the roughness and mechanical properties of the surface at the submicrometer scale, enabling the investigation of the degradation processes. In this work the deterioration of selected group of polyethylene based materials have been measured by means of AFM, as the samples were exposed to the simulated solar light and UV-C radiation. Such an analysis of the environmental conditions impact on the deterioration process using AFM methods for various versions of specific material was not presented before. (paper)

  18. Possible influences of Asian dust aerosols on cloud properties and radiative forcing observed from MODIS and CERES

    Science.gov (United States)

    Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

    2006-03-01

    The effects of dust storms on cloud properties and Radiative Forcing (RF) are analyzed over Northwestern China from April 2001 to June 2004 using data collected by the MODerate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. Due to changes in cloud microphysics, the instantaneous net RF is increased from -161.6 W/m2 for dust-free clouds to -118.6 W/m2 for dust-contaminated clouds.

  19. The Relationship Between Radiative Forcing and Temperature. What Do Statistical Analyses of the Instrumental Temperature Record Measure?

    International Nuclear Information System (INIS)

    Kaufmann, R.K.; Kauppi, H.; Stock, J.H.

    2006-01-01

    Comparing statistical estimates for the long-run temperature effect of doubled CO2 with those generated by climate models begs the question, is the long-run temperature effect of doubled CO2 that is estimated from the instrumental temperature record using statistical techniques consistent with the transient climate response, the equilibrium climate sensitivity, or the effective climate sensitivity. Here, we attempt to answer the question, what do statistical analyses of the observational record measure, by using these same statistical techniques to estimate the temperature effect of a doubling in the atmospheric concentration of carbon dioxide from seventeen simulations run for the Coupled Model Intercomparison Project 2 (CMIP2). The results indicate that the temperature effect estimated by the statistical methodology is consistent with the transient climate response and that this consistency is relatively unaffected by sample size or the increase in radiative forcing in the sample

  20. Acoustic radiation force impulse elastography of the kidneys: is shear wave velocity affected by tissue fibrosis or renal blood flow?

    Science.gov (United States)

    Asano, Kenichiro; Ogata, Ai; Tanaka, Keiko; Ide, Yoko; Sankoda, Akiko; Kawakita, Chieko; Nishikawa, Mana; Ohmori, Kazuyoshi; Kinomura, Masaru; Shimada, Noriaki; Fukushima, Masaki

    2014-05-01

    The aim of this study was to identify the main influencing factor of the shear wave velocity (SWV) of the kidneys measured by acoustic radiation force impulse elastography. The SWV was measured in the kidneys of 14 healthy volunteers and 319 patients with chronic kidney disease. The estimated glomerular filtration rate was calculated by the serum creatinine concentration and age. As an indicator of arteriosclerosis of large vessels, the brachial-ankle pulse wave velocity was measured in 183 patients. Compared to the degree of interobserver and intraobserver deviation, a large variance of SWV values was observed in the kidneys of the patients with chronic kidney disease. Shear wave velocity values in the right and left kidneys of each patient correlated well, with high correlation coefficients (r = 0.580-0.732). The SWV decreased concurrently with a decline in the estimated glomerular filtration rate. A low SWV was obtained in patients with a high brachial-ankle pulse wave velocity. Despite progression of renal fibrosis in the advanced stages of chronic kidney disease, these results were in contrast to findings for chronic liver disease, in which progression of hepatic fibrosis results in an increase in the SWV. Considering that a high brachial-ankle pulse wave velocity represents the progression of arteriosclerosis in the large vessels, the reduction of elasticity succeeding diminution of blood flow was suspected to be the main influencing factor of the SWV in the kidneys. This study indicates that diminution of blood flow may affect SWV values in the kidneys more than the progression of tissue fibrosis. Future studies for reducing data variance are needed for effective use of acoustic radiation force impulse elastography in patients with chronic kidney disease.

  1. Aging of black carbon particles under polluted urban environments: timescale, hygroscopicity and enhanced absorption and direct radiative forcing

    Science.gov (United States)

    Peng, J.; Hu, M.; Guo, S.; Du, Z.; Zheng, J.; Shang, D.; Levy Zamora, M.; Shao, M.; Wu, Y.; Zheng, J.; Wang, Y.; Zeng, L.; Collins, D. R.; Molina, M.; Zhang, R.

    2017-12-01

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the hygroscopic and optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using an outdoor environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. The κ (kappa) values of coating materials are calculated as 0.04 at both subsaturation and supersaturation conditions, respectively, indicating that the initial photochemical aging of BC particles does not appreciably alter the BC hygroscopicity. Our findings suggest that BC aging under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

  2. Fire-induced albedo change and surface radiative forcing in sub-Saharan Africa savanna ecosystems: Implications for the energy balance

    Science.gov (United States)

    Dintwe, Kebonye; Okin, Gregory S.; Xue, Yongkang

    2017-06-01

    Surface albedo is a critical parameter that controls surface energy balance. In dryland ecosystems, fires play a significant role in decreasing surface albedo, resulting in positive radiative forcing. Here we investigate the long-term effect of fire on surface albedo. We devised a method to calculate short-, medium-, and long-term effect of fire-induced radiative forcing and their relative effects on energy balance. We used Moderate Resolution Imaging Spectroradiometer (MODIS) data in our analysis, covering different vegetation classes in sub-Saharan Africa (SSA). Our analysis indicated that mean short-term fire-induced albedo change in SSA was -0.022, -0.035, and -0.041 for savannas, shrubland, and grasslands, respectively. At regional scale, mean fire-induced albedo change in savannas was -0.018 and -0.024 for northern sub-Saharan of Africa and the southern hemisphere Africa, respectively. The short-term mean fire-induced radiative forcing in burned areas in sub-Saharan Africa (SSA) was 5.41 W m-2, which contributed continental and global radiative forcings of 0.25 and 0.058 W m-2, respectively. The impact of fire in surface albedo has long-lasting effects that varies with vegetation type. The long-term energetic effects of fire-induced albedo change and associated radiative forcing were, on average, more than 19 times greater across SSA than the short-term effects, suggesting that fires exerted far more radiative forcing than previously thought. Taking into account the actual duration of fire's effect on surface albedo, we conclude that the contribution of SSA fires, globally and throughout the year, is 0.12 W m-2. These findings provide crucial information on possible impact of fire on regional climate variability.

  3. Mechanism of the quasi-zero axial acoustic radiation force experienced by elastic and viscoelastic spheres in the field of a quasi-Gaussian beam and particle tweezing.

    Science.gov (United States)

    Mitri, F G; Fellah, Z E A

    2014-01-01

    The present analysis investigates the (axial) acoustic radiation force induced by a quasi-Gaussian beam centered on an elastic and a viscoelastic (polymer-type) sphere in a nonviscous fluid. The quasi-Gaussian beam is an exact solution of the source free Helmholtz wave equation and is characterized by an arbitrary waist w₀ and a diffraction convergence length known as the Rayleigh range z(R). Examples are found where the radiation force unexpectedly approaches closely to zero at some of the elastic sphere's resonance frequencies for kw₀≤1 (where this range is of particular interest in describing strongly focused or divergent beams), which may produce particle immobilization along the axial direction. Moreover, the (quasi)vanishing behavior of the radiation force is found to be correlated with conditions giving extinction of the backscattering by the quasi-Gaussian beam. Furthermore, the mechanism for the quasi-zero force is studied theoretically by analyzing the contributions of the kinetic, potential and momentum flux energy densities and their density functions. It is found that all the components vanish simultaneously at the selected ka values for the nulls. However, for a viscoelastic sphere, acoustic absorption degrades the quasi-zero radiation force. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. The footprint of Alaskan tundra fires during the past half-century: implications for surface properties and radiative forcing

    International Nuclear Information System (INIS)

    Rocha, Adrian V; Loranty, Michael M; Higuera, Phil E; Mack, Michelle C; Hu Fengsheng; Jones, Benjamin M; Breen, Amy L; Rastetter, Edward B; Shaver, Gus R; Goetz, Scott J

    2012-01-01

    Recent large and frequent fires above the Alaskan arctic circle have forced a reassessment of the ecological and climatological importance of fire in arctic tundra ecosystems. Here we provide a general overview of the occurrence, distribution, and ecological and climate implications of Alaskan tundra fires over the past half-century using spatially explicit climate, fire, vegetation and remote sensing datasets for Alaska. Our analyses highlight the importance of vegetation biomass and environmental conditions in regulating tundra burning, and demonstrate that most tundra ecosystems are susceptible to burn, providing the environmental conditions are right. Over the past two decades, fire perimeters above the arctic circle have increased in size and importance, especially on the North Slope, indicating that future wildfire projections should account for fire regime changes in these regions. Remote sensing data and a literature review of thaw depths indicate that tundra fires have both positive and negative implications for climatic feedbacks including a decadal increase in albedo radiative forcing immediately after a fire, a stimulation of surface greenness and a persistent long-term (>10 year) increase in thaw depth. In order to address the future impact of tundra fires on climate, a better understanding of the control of tundra fire occurrence as well as the long-term impacts on ecosystem carbon cycling will be required. (letter)

  5. Analysis of radiation pressure force exerted on a biological cell induced by high-order Bessel beams using Debye series

    International Nuclear Information System (INIS)

    Li, Renxian; Ren, Kuan Fang; Han, Xiang'e; Wu, Zhensen; Guo, Lixin; Gong, Shuxi

    2013-01-01

    Debye series expansion (DSE) is employed to the analysis of radiation pressure force (RPF) exerted on biological cells induced by high-order Bessel beams (BB). The beam shape coefficients (BSCs) for high-order Bessel beams are calculated using analytical expressions obtained by the integral localized approximation (ILA). Different types of cells, including a real Chinese Hamster Ovary (CHO) cell and a lymphocyte which are respectively modeled by a coated and five-layered sphere, are considered. The RPF induced by high-order Bessel beams is compared with that by Gaussian beams and zeroth-order Bessel beams, and the effect of different scattering processes on RPF is studied. Numerical calculations show that high-order Bessel beams with zero central intensity can also transversely trap particle in the beam center, and some scattering processes can provide longitudinal pulling force. -- Highlights: ► BSCs for high-order Bessel beam (HOBB) is derived using ILA. ► DSE is employed to study the RPF induced by HOBB exerted on multilayered cells. ► RPF is decided by radius relative to the interval of peaks in intensity profile. ► HOBB can also transversely trap high-index particle in the vicinity of beam axis. ► RPF for some scattering processes can longitudinally pull particles back

  6. Varying the agglomeration position of particles in a micro-channel using Acoustic Radiation Force beyond the resonance condition.

    Science.gov (United States)

    Dron, Olivier; Aider, Jean-Luc

    2013-09-01

    It is well-known that particles can be focused at mid-height of a micro-channel using Acoustic Radiation Force (ARF) tuned at the resonance frequency (h=λ/2). The resonance condition is a strong limitation to the use of acoustophoresis (particles manipulation using acoustic force) in many applications. In this study we show that it is possible to focus the particles anywhere along the height of a micro-channel just by varying the acoustic frequency, in contradiction with the resonance condition. This result has been thoroughly checked experimentally. The different physical properties as well as wall materials have been changed. The wall materials is finally the only critical parameters. One of the specificity of the micro-channel is the thickness of the carrier and reflector layer. A preliminary analysis of the experimental results suggests that the acoustic focusing beyond the classic resonance condition can be explained in the framework of the multilayered resonator proposed by Hill [1]. Nevertheless, further numerical studies are needed in order to confirm and fully understand how the acoustic pressure node can be moved over the entire height of the micro channel by varying the acoustic frequency. Despite some uncertainties about the origin of the phenomenon, it is robust and can be used for improved acoustic sorting or manipulation of particles or biological cells in confined set-ups. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. The influence of cirrus cloud-radiative forcing on climate and climate sensitivity in a general circulation model

    International Nuclear Information System (INIS)

    Lohmann, U.; Roeckner, E.

    1994-01-01

    Six numerical experiments have been performed with a general circulation model (GCM) to study the influence of high-level cirrus clouds and global sea surface temperature (SST) perturbations on climate and climate sensitivity. The GCM used in this investigation is the third-generation ECHAM3 model developed jointly by the Max-Planck-Institute for Meteorology and the University of Hamburg. It is shown that the model is able to reproduce many features of the observed cloud-radiative forcing with considerable skill, such as the annual mean distribution, the response to seasonal forcing and the response to observed SST variations in the equatorial Pacific. In addition to a reference experiment where the cirrus emissivity is computed as a function of the cloud water content, two sensitivity experiments have been performed in which the cirrus emissivity is either set to zero everywhere above 400 hPa ('transparent cirrus') or set to one ('black cirrus'). These three experiments are repeated identically, except for prescribing a globally uniform SST warming of 4 K. (orig.)

  8. Is ultra-violet radiation the main force shaping molecular evolution of varicella-zoster virus?

    Science.gov (United States)

    2011-01-01

    Background Varicella (chickenpox) exhibits a characteristic epidemiological pattern which is associated with climate. In general, primary infections in tropical regions are comparatively less frequent among children than in temperate regions. This peculiarity regarding varicella-zoster virus (VZV) infection among certain age groups in tropical regions results in increased susceptibility during adulthood in these regions. Moreover, this disease shows a cyclic behavior in which the number of cases increases significantly during winter and spring. This observation further supports the participation of environmental factors in global epidemiology of chickenpox. However, the underlying mechanisms responsible for this distinctive disease behavior are not understood completely. In a recent publication, Philip S. Rice has put forward an interesting hypothesis suggesting that ultra-violet (UV) radiation is the major environmental factor driving the molecular evolution of VZV. Discussion While we welcomed the attempt to explain the mechanisms controlling VZV transmission and distribution, we argue that Rice's hypothesis takes lightly the circulation of the so called "temperate VZV genotypes" in tropical regions and, to certain degree, overlooks the predominance of such lineages in certain non-temperate areas. Here, we further discuss and present new information about the overwhelming dominance of temperate VZV genotypes in Mexico regardless of geographical location and climate. Summary UV radiation does not satisfactorily explain the distribution of VZV genotypes in different tropical and temperate regions of Mexico. Additionally, the cyclic behavior of varicella does not shown significant differences between regions with different climates in the country. More studies should be conducted to identify the factors directly involved in viral spreading. A better understanding of the modes of transmissions exploited by VZV and their effect on viral fitness is likely to facilitate

  9. Is ultra-violet radiation the main force shaping molecular evolution of varicella-zoster virus?

    Directory of Open Access Journals (Sweden)

    Escobar-Gutiérrez Alejandro

    2011-07-01

    Full Text Available Abstract Background Varicella (chickenpox exhibits a characteristic epidemiological pattern which is associated with climate. In general, primary infections in tropical regions are comparatively less frequent among children than in temperate regions. This peculiarity regarding varicella-zoster virus (VZV infection among certain age groups in tropical regions results in increased susceptibility during adulthood in these regions. Moreover, this disease shows a cyclic behavior in which the number of cases increases significantly during winter and spring. This observation further supports the participation of environmental factors in global epidemiology of chickenpox. However, the underlying mechanisms responsible for this distinctive disease behavior are not understood completely. In a recent publication, Philip S. Rice has put forward an interesting hypothesis suggesting that ultra-violet (UV radiation is the major environmental factor driving the molecular evolution of VZV. Discussion While we welcomed the attempt to explain the mechanisms controlling VZV transmission and distribution, we argue that Rice's hypothesis takes lightly the circulation of the so called "temperate VZV genotypes" in tropical regions and, to certain degree, overlooks the predominance of such lineages in certain non-temperate areas. Here, we further discuss and present new information about the overwhelming dominance of temperate VZV genotypes in Mexico regardless of geographical location and climate. Summary UV radiation does not satisfactorily explain the distribution of VZV genotypes in different tropical and temperate regions of Mexico. Additionally, the cyclic behavior of varicella does not shown significant differences between regions with different climates in the country. More studies should be conducted to identify the factors directly involved in viral spreading. A better understanding of the modes of transmissions exploited by VZV and their effect on viral

  10. Dust scattering and the radiation pressure force in the M82 superwind

    Energy Technology Data Exchange (ETDEWEB)

    Coker, Carl T.; Thompson, Todd A.; Martini, Paul, E-mail: coker@astronomy.ohio-state.edu, E-mail: thompson@astronomy.ohio-state.edu, E-mail: martini@astronomy.ohio-state.edu [Department of Astronomy and Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210 (United States)

    2013-11-20

    Radiation pressure on dust grains may be an important physical mechanism driving galaxy-wide superwinds in rapidly star-forming galaxies. We calculate the combined dust and gas Eddington ratio (Γ) for the archetypal superwind of M82. By combining archival Galaxy Evolution Explorer data, a standard dust model, Monte Carlo dust scattering calculations, and the Herschel map of the dust surface density distribution, the observed far-UV/near-UV surface brightness in the outflow constrains both the total UV luminosity escaping from the starburst along its minor axis (L {sub *,UV}) and the flux-mean opacity, thus allowing a calculation of Γ. We find that L {sub *,UV} ≈ (1-6) × 10{sup 42} erg s{sup –1}, ∼2-12 times greater than the UV luminosity observed from our line of sight. On a scale of 1-3 kpc above the plane of M82, we find that Γ ∼ 0.01-0.06. On smaller scales (∼0.25-0.5 kpc), where the enclosed mass decreases, our calculation of L {sub *,UV} implies that Γ ∼ 0.1 with factor of few uncertainties. Within the starburst itself, we estimate the single-scattering Eddington ratio to be of order unity. Thus, although radiation pressure is weak compared to gravity on kpc scales above the plane of M82, it may yet be important in launching the observed outflow. We discuss the primary uncertainties in our calculation, the sensitivity of Γ to the dust grain size distribution, and the time evolution of the wind following M82's recent starburst episodes.

  11. Dust scattering and the radiation pressure force in the M82 superwind

    International Nuclear Information System (INIS)

    Coker, Carl T.; Thompson, Todd A.; Martini, Paul

    2013-01-01

    Radiation pressure on dust grains may be an important physical mechanism driving galaxy-wide superwinds in rapidly star-forming galaxies. We calculate the combined dust and gas Eddington ratio (Γ) for the archetypal superwind of M82. By combining archival Galaxy Evolution Explorer data, a standard dust model, Monte Carlo dust scattering calculations, and the Herschel map of the dust surface density distribution, the observed far-UV/near-UV surface brightness in the outflow constrains both the total UV luminosity escaping from the starburst along its minor axis (L *,UV ) and the flux-mean opacity, thus allowing a calculation of Γ. We find that L *,UV ≈ (1-6) × 10 42 erg s –1 , ∼2-12 times greater than the UV luminosity observed from our line of sight. On a scale of 1-3 kpc above the plane of M82, we find that Γ ∼ 0.01-0.06. On smaller scales (∼0.25-0.5 kpc), where the enclosed mass decreases, our calculation of L *,UV implies that Γ ∼ 0.1 with factor of few uncertainties. Within the starburst itself, we estimate the single-scattering Eddington ratio to be of order unity. Thus, although radiation pressure is weak compared to gravity on kpc scales above the plane of M82, it may yet be important in launching the observed outflow. We discuss the primary uncertainties in our calculation, the sensitivity of Γ to the dust grain size distribution, and the time evolution of the wind following M82's recent starburst episodes.

  12. Effects of acoustic radiation force and shear waves for absorption and stiffness sensing in ultrasound modulated optical tomography.

    Science.gov (United States)

    Li, Rui; Elson, Daniel S; Dunsby, Chris; Eckersley, Robert; Tang, Meng-Xing

    2011-04-11

    Ultrasound-modulated optical tomography (UOT) combines optical contrast with ultrasound spatial resolution and has great potential for soft tissue functional imaging. One current problem with this technique is the weak optical modulation signal, primarily due to strong optical scattering in diffuse media and minimal acoustically induced modulation. The acoustic radiation force (ARF) can create large particle displacements in tissue and has been shown to be able to improve optical modulation signals. However, shear wave propagation induced by the ARF can be a significant source of nonlocal optical modulation which may reduce UOT spatial resolution and contrast. In this paper, the time evolution of shear waves was examined on tissue mimicking-phantoms exposed to 5 MHz ultrasound and 532 nm optical radiation and measured with a CCD camera. It has been demonstrated that by generating an ARF with an acoustic burst and adjusting both the timing and the exposure time of the CCD measurement, optical contrast and spatial resolution can be improved by ~110% and ~40% respectively when using the ARF rather than 5 MHz ultrasound alone. Furthermore, it has been demonstrated that this technique simultaneously detects both optical and mechanical contrast in the medium and the optical and mechanical contrast can be distinguished by adjusting the CCD exposure time. © 2011 Optical Society of America

  13. Radiation

    International Nuclear Information System (INIS)

    2013-01-01

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  14. MODIS Observation of Aerosols over Southern Africa During SAFARI 2000: Data, Validation, and Estimation of Aerosol Radiative Forcing

    Science.gov (United States)

    Ichoku, Charles; Kaufman, Yoram; Remer, Lorraine; Chu, D. Allen; Mattoo, Shana; Tanre, Didier; Levy, Robert; Li, Rong-Rong; Kleidman, Richard; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Aerosol properties, including optical thickness and size parameters, are retrieved operationally from the MODIS sensor onboard the Terra satellite launched on 18 December 1999. The predominant aerosol type over the Southern African region is smoke, which is generated from biomass burning on land and transported over the southern Atlantic Ocean. The SAFARI-2000 period experienced smoke aerosol emissions from the regular biomass burning activities as well as from the prescribed burns administered on the auspices of the experiment. The MODIS Aerosol Science Team (MAST) formulates and implements strategies for the retrieval of aerosol products from MODIS, as well as for validating and analyzing them in order to estimate aerosol effects in the radiative forcing of climate as accurately as possible. These activities are carried out not only from a global perspective, but also with a focus on specific regions identified as having interesting characteristics, such as the biomass burning phenomenon in southern Africa and the associated smoke aerosol, particulate, and trace gas emissions. Indeed, the SAFARI-2000 aerosol measurements from the ground and from aircraft, along with MODIS, provide excellent data sources for a more intensive validation and a closer study of the aerosol characteristics over Southern Africa. The SAFARI-2000 ground-based measurements of aerosol optical thickness (AOT) from both the automatic Aerosol Robotic Network (AERONET) and handheld Sun photometers have been used to validate MODIS retrievals, based on a sophisticated spatio-temporal technique. The average global monthly distribution of aerosol from MODIS has been combined with other data to calculate the southern African aerosol daily averaged (24 hr) radiative forcing over the ocean for September 2000. It is estimated that on the average, for cloud free conditions over an area of 9 million square kin, this predominantly smoke aerosol exerts a forcing of -30 W/square m C lose to the terrestrial

  15. Diurnal and seasonal characteristics of the optical properties and direct radiative forcing of different aerosol components in Seoul megacity.

    Science.gov (United States)

    Song, Sang-Keun; Shon, Zang-Ho; Park, Yeon-Hee

    2017-12-01

    The temporal variations (diurnal and seasonal) of the optical properties and direct aerosol radiative forcing (DARF) of different aerosol components (water-soluble, insoluble, black carbon (BC), and sea-salt) were analyzed using the hourly resolution data (PM 2.5 ) measured at an urban site in Seoul, Korea during 2010, based on a modeling approach. In general, the water-soluble component was predominant over all other components (with a higher concentration) in terms of its impact on the optical properties (except for absorbing BC) and DARF. The annual mean aerosol optical depth (AOD, τ) at 500nm for the water-soluble component was 0.38±0.07 (0.06±0.01 for BC). The forcing at the surface (DARF SFC ) and top of the atmosphere (DARF TOA ), and in the atmosphere (DARF ATM ) for most aerosol components (except for BC) during the daytime were highest in spring and lowest in late fall or early winter. The maximum DARF SFC occurred in the morning during most seasons (except for the water-soluble components showing peaks in the afternoon or noon in summer, fall, or winter), while the maximum DARF TOA occurred in the morning during spring and/or winter and in the afternoon during summer and/or fall. The estimated DARF SFC and DARF ATM of the water-soluble component were in the range of -49 to -84Wm -2 and +10 to +22Wm -2 , respectively. The DARF SFC and DARF ATM of BC were -26 to -39Wm -2 and +32 to +51Wm -2 , respectively, showing highest in summer and lowest in spring, with morning peaks regardless of the season. This positive DARF ATM of BC in this study area accounted for approximately 64% of the total atmospheric aerosol forcing due to strong radiative absorption, thus increasing atmospheric heating by 2.9±1.2Kday -1 (heating rate efficiency of 39K day -1 τ -1 ) and then causing further atmospheric warming. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Assessment of aerosols optical properties and radiative forcing over an Urban site in North-Western India.

    Science.gov (United States)

    Mor, Vikram; Dhankhar, Rajesh; Attri, S D; Soni, V K; Sateesh, M; Taneja, Kanika

    2017-05-01

    The present work is aimed to analyze aerosols optical properties and to estimate aerosol radiative forcing (ARF) from January to December 2013, using sky radiometer data over Rohtak, an urban site in North-Western India. The results reveal strong wavelength dependency of aerosol optical depth (AOD), with high values of AOD at shorter wavelengths and lower values at longer wavelength during the study period. The highest AOD values of 1.07 ± 0.45 at 500 nm were observed during July. A significant decline in Ångström exponent was observed during April-May, which represents the dominance of coarse mode particles due to dust-raising convective activities. Aerosols' size distribution exhibits a bimodal structure with fine mode particles around 0.17 µm and coarse mode particles with a radius around 5.28 µm. Single scattering albedo values were lowest during November-December at all wavelengths, ranging from 0.87 to 0.76, which corresponds to the higher absorption during this period. Aerosols optical properties retrieved during observation period are used as input for SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) to estimate the direct ARF at the surface, in the atmosphere and at the top of the atmosphere (TOA). The ARF at the TOA, surface and in the atmosphere are found to be in the range of -4.98 to -19.35 W m -2 , -8.01 to -57.66 W m -2 and +3.02 to +41.64 W m -2 , respectively. The averaged forcing for the whole period of observations at the TOA is -11.26 W m -2 , while at the surface it is -38.64 W m -2 , leading to atmospheric forcing of 27.38 W m -2 . The highest (1.168 K day -1 ) values of heating rate was estimated during November, whereas the lowest value (0.084 K day -1 ) was estimated for the February.

  17. Aerosol optical, microphysical and radiative forcing properties during variable intensity African dust events in the Iberian Peninsula

    Science.gov (United States)

    Fernández, A. J.; Molero, F.; Salvador, P.; Revuelta, A.; Becerril-Valle, M.; Gómez-Moreno, F. J.; Artíñano, B.; Pujadas, M.

    2017-11-01

    Aerosol measurements at two AERONET (AErosol RObotic NETwork) sites of the Iberian Peninsula: Madrid (40°.45N, 3.72W) and La Coruña (43°.36N, 8°.42W) have been analyzed for the period 2012-2015 to assess aerosol optical properties (intensive and extensive) throughout the atmospheric column and their radiative forcing (RF) and radiative forcing efficiency (RFeff) estimates at the Bottom and Top Of Atmosphere (BOA and TOA respectively). Specific conditions as dust-free and African dust have been considered for the study. Unprecedented, this work uses the quantification of the African dust aerosol at ground level which allows us to study such AERONET products at different intensity levels of African events: Low (L), High (H) and very high (VH). The statistical difference between dust-free and African dust conditions on the aforementioned parameters, quantified by means of the non-parametric Kolmogorov-Smirnov test, is quite clear in Madrid, however it is not in La Coruña. Scattering Angstrom Exponent (SAE) and Absorption Angstrom Exponent (AAE) were found to be 1.64 ± 0.29 and 1.14 ± 0.23 respectively in Madrid for dust-free conditions because typical aerosol sources are traffic emissions and residential heating, and black carbon is an important compound in this aerosol kind. On the other hand, SAE and AAE were 0.96 ± 0.60 and 1.44 ± 0.51 for African dust conditions in this location. RF (at shortwave radiation) seems to decrease as the African dust contribution at ground level is larger which indicates the cooling effect of African dust aerosol in Madrid. We have also proved the potential of a 2D-cluster analysis based on AAE and SAE to differentiate both situations in Madrid. Conversely, it is suggested that aerosols observed in La Coruña under dust-free conditions might come from different sources. Then, SAE and AAE are not good enough indicators to distinguish between dust-free and African dust conditions. Besides, as La Coruña is at a further distance

  18. Brightening of the global cloud field by nitric acid and the associated radiative forcing

    Directory of Open Access Journals (Sweden)

    R. Makkonen

    2012-08-01

    Full Text Available Clouds cool Earth's climate by reflecting 20% of the incoming solar energy, while also trapping part of the outgoing radiation. The effect of human activities on clouds is poorly understood, but the present-day anthropogenic cooling via changes of cloud albedo and lifetime could be of the same order as warming from anthropogenic addition in CO2. Soluble trace gases can increase water condensation to particles, possibly leading to activation of smaller aerosols and more numerous cloud droplets. We have studied the effect of nitric acid on the aerosol indirect effect with the global aerosol-climate model ECHAM5.5-HAM2. Including the nitric acid effect in the model increases cloud droplet number concentrations globally by 7%. The nitric acid contribution to the present-day cloud albedo effect was found to be −0.32 W m−2 and to the total indirect effect −0.46 W m−2. The contribution to the cloud albedo effect is shown to increase to −0.37 W m−2 by the year 2100, if considering only the reductions in available cloud condensation nuclei. Overall, the effect of nitric acid can play a large part in aerosol cooling during the following decades with decreasing SO2 emissions and increasing NOx and greenhouse gases.

  19. EDF FARN (fast action force in case of nuclear accident) - Focus on radiation protection of workers

    International Nuclear Information System (INIS)

    Le Guen, Bernard

    2014-01-01

    fully operational in an autonomous manner within 24 hours. Within this emergency response context, the radiological risk for the public, incorporated in the ability to reinstate the environmental measurement networks if they have been destroyed is factored into design, mainly with construction of the new emergency response management centre. In addition to the site equipment and human resources, the FARN has personnel trained in RP and stress management in emergency situations, personnel specialised in radiation protection in the field, an RP expert who coordinates response actions in radiation protection terms and a site doctor. Concerning equipment resources, EDF has opted for robust RP equipment common to all its personnel, factoring in Fukushima operating experience, both for worker protection and monitoring and for equipment and procedures appropriate to a high level of background noise. In order to reinstate environmental measurements, modular equipment enables the networks to be increasingly set up as and when the external emergency services arrive. The principle of radiological risk management is based on progressive scheduled enhancement of the different items of RP equipment provided for monitoring and optimum protection of the public and all the emergency response teams, right from the very start and throughout response. The shift crews present on site thus take the first radiation protection actions: worker protection, partial reinstatement of the radiation monitoring network providing the public authorities with information so that they can fulfil their remit of public protection. This approach is supplemented with assessment of release into the atmosphere and analysis of radiological impact using predictive tools at corporate level. Deployment of the FARN with additional input of equipment enables a complete environmental monitoring network to be reinstated within 24 hours, if need be, and additional radiological monitoring equipment to be deployed. Lastly

  20. Elevated atmospheric CO2 negatively impacts photosynthesis through radiative forcing and physiology-mediated climate feedback

    Science.gov (United States)

    Zhu, Peng; Zhuang, Qianlai; Ciais, Philippe; Welp, Lisa; Li, Wenyu; Xin, Qinchuan

    2017-02-01

    Increasing atmospheric CO2 affects photosynthesis involving directly increasing leaf carboxylation rates, stomatal closure, and climatic effects. The direct effects are generally thought to be positive leading to increased photosynthesis, while its climatic effects can be regionally positive or negative. These effects are usually considered to be independent from each other, but they are in fact coupled through interactions between land surface exchanges of gases and heat and the physical climate system. In particular, stomatal closure reduces evapotranspiration and increases sensible heat emissions from ecosystems, leading to decreased atmospheric moisture and precipitation and local warming. We use a coupled earth system model to attribute the influence of the increase in CO2 on gross primary productivity (GPP) during the period of 1930-2011. In our model, CO2 radiative effects cause climate change that has only a negligible effect on global GPP (a reduction of 0.9 ± 2% during the last 80 years) because of opposite responses between tropical and northern biomes. On the other hand, CO2 physiological effects on GPP are both positive, by increased carboxylation rates and water use efficiency (7.1 ± 0.48% increase), and negative, by vegetation-climate feedback reducing precipitation, as a consequence of decreased transpiration and increased sensible heat in areas without water limitation (2.7 ± 1.76% reduction).When considering the coupled atmosphere-vegetation system, negative climate feedback on photosynthesis and plant growth due to the current level of CO2 opposes 29-38% of the gains from direct fertilization effects.

  1. ACOUSTIC RADIATION FORCE IMPULSE IS EQUIVALENT TO LIVER BIOPSY TO EVALUATE LIVER FIBROSIS IN PATIENTS WITH CHRONIC HEPATITIS C AND NONALCOHOLIC FATTY LIVER DISEASE

    Directory of Open Access Journals (Sweden)

    Juliana Ayres de Alencar Arrais GUERRA

    2015-09-01

    Full Text Available BackgroundLiver biopsy is recommended as the gold standard method for assessing the stage of liver fibrosis in patients with chronic liver disease. However, it is invasive, with potential risks and complications. Elastography is an ultrasound technique that provides information of changes in the liver tissue, evaluating tissue elasticity and acoustic radiation force impulse is one of the available techniques.ObjectiveThe main objective of this study was to evaluate the sensitivity and specificity of acoustic radiation force impulse comparing to liver biopsy to evaluate fibrosis in patients with chronic hepatitis C virus and nonalcoholic fatty liver disease.MethodsTwenty four patients were included, everyone underwent liver biopsy and acoustic radiation force impulse, and the results were compared with values described in the literature by several authors.ResultsIn the population of patients with chronic hepatitis C, our data were better correlated with data published by Carmen Fierbinteanu-Braticevici et al., with an accuracy of 82.4%, sensitivity of 71.4% and specificity of 90%. For nonalcoholic fatty liver disease, our data were better correlated with data published by Masato Yoneda et al., with an accuracy of 85.7%, sensitivity 80% and specificity of 100%.ConclusionAcoustic radiation force impulse is a method with good accuracy to distinguish initial fibrosis from advanced fibrosis in hepatitis C virus and nonalcoholic fatty liver disease and can replace biopsy in most cases.

  2. The Role of Long-Lived Greenhouse Gases as Principal LW Control Knob that Governs the Global Surface Temperature for Past and Future Climate Change

    Science.gov (United States)

    Lacis, Andrew A.; Hansen, James E.; Russell, Gary L.; Oinas, Valdar; Jonas, Jeffrey

    2013-01-01

    The climate system of the Earth is endowed with a moderately strong greenhouse effect that is characterized by non-condensing greenhouse gases (GHGs) that provide the core radiative forcing. Of these, the most important is atmospheric CO2. There is a strong feedback contribution to the greenhouse effect by water vapor and clouds that is unique in the solar system, exceeding the core radiative forcing due to the non-condensing GHGs by a factor of three. The significance of the non-condensing GHGs is that once they have been injected into the atmosphere, they remain there virtually indefinitely because they do not condense and precipitate from the atmosphere, their chemical removal time ranging from decades to millennia. Water vapor and clouds have only a short lifespan, with their distribution determined by the locally prevailing meteorological conditions, subject to Clausius-Clapeyron constraint. Although solar irradiance is the ultimate energy source that powers the terrestrial greenhouse effect, there has been no discernible long-term trend in solar irradiance since precise monitoring began in the late 1970s. This leaves atmospheric CO2 as the effective control knob driving the current global warming trend. Over geological time scales, volcanoes are the principal source of atmospheric CO2, and the weathering of rocks is the principal sink, with the biosphere participating as both a source and a sink. The problem at hand is that human industrial activity is causing atmospheric CO2, to increase by 2 ppm per year, whereas the interglacial rate has been 0.005 ppm per year. This is a geologically unprecedented rate to turn the CO2 climate control knob. This is causing the global warming that threatens the global environment.

  3. The role of long-lived greenhouse gases as principal LW control knob that governs the global surface temperature for past and future climate change

    Directory of Open Access Journals (Sweden)

    Andrew A. Lacis

    2013-11-01

    Full Text Available The climate system of the Earth is endowed with a moderately strong greenhouse effect that is characterised by non-condensing greenhouse gases (GHGs that provide the core radiative forcing. Of these, the most important is atmospheric CO2. There is a strong feedback contribution to the greenhouse effect by water vapour and clouds that is unique in the solar system, exceeding the core radiative forcing due to the non-condensing GHGs by a factor of three. The significance of the non-condensing GHGs is that once they have been injected into the atmosphere, they remain there virtually indefinitely because they do not condense and precipitate from the atmosphere, their chemical removal time ranging from decades to millennia. Water vapour and clouds have only a short lifespan, with their distribution determined by the locally prevailing meteorological conditions, subject to Clausius–Clapeyron constraint. Although solar irradiance is the ultimate energy source that powers the terrestrial greenhouse effect, there has been no discernable long-term trend in solar irradiance since precise monitoring began in the late 1970s. This leaves atmospheric CO2 as the effective control knob driving the current global warming trend. Over geological time scales, volcanoes are the principal source of atmospheric CO2, and the weathering of rocks is the principal sink, with the biosphere participating as both a source and a sink. The problem at hand is that human industrial activity is causing atmospheric CO2, to increase by 2 ppm yr−1, whereas the interglacial rate has been 0.005 ppm yr−1. This is a geologically unprecedented rate to turn the CO2 climate control knob. This is causing the global warming that threatens the global environment.

  4. The role of long-lived greenhouse gases as principal LW control knob that governs the global surface temperature for past and future climate change

    Energy Technology Data Exchange (ETDEWEB)

    Lacis, Andrew A.; Hansen, James E.; Russell, Gary L.; Oinas, Valdar; Jonas, Jeffrey [NASA Goddard Inst. for Space Studies, New York (United States)], e-mail: Andrew.A.Lacis@nasa.gov

    2013-11-15

    The climate system of the Earth is endowed with a moderately strong greenhouse effect that is characterised by non-condensing greenhouse gases (GHGs) that provide the core radiative forcing. Of these, the most important is atmospheric CO{sub 2}. There is a strong feedback contribution to the greenhouse effect by water vapour and clouds that is unique in the solar system, exceeding the core radiative forcing due to the non-condensing GHGs by a factor of three. The significance of the non-condensing GHGs is that once they have been injected into the atmosphere, they remain there virtually indefinitely because they do not condense and precipitate from the atmosphere, their chemical removal time ranging from decades to millennia. Water vapour and clouds have only a short lifespan, with their distribution determined by the locally prevailing meteorological conditions, subject to Clausius-Clapeyron constraint. Although solar irradiance is the ultimate energy source that powers the terrestrial greenhouse effect, there has been no discern able long-term trend in solar irradiance since precise monitoring began in the late seventies. This leaves atmospheric CO{sub 2} as the effective control knob driving the current global warming trend. Over geological time scales, volcanoes are the principal source of atmospheric CO{sub 2}, and the weathering of rocks is the principal sink, with the biosphere participating as both a source and a sink. The problem at hand is that human industrial activity is causing atmospheric CO{sub 2}, to increase by 2 ppm yr{sup -1}, whereas the interglacial rate has been 0.005 ppm yr{sup -1}. This is a geologically unprecedented rate to turn the CO{sub 2} climate control knob. This is causing the global warming that threatens the global environment.

  5. Direct Aerosol Radiative Forcing from Combined A-Train Observations - Preliminary Comparisons with AeroCom Models and Pathways to Observationally Based All-sky Estimates

    Science.gov (United States)

    Redemann, J.; Livingston, J. M.; Shinozuka, Y.; Kacenelenbogen, M. S.; Russell, P. B.; LeBlanc, S. E.; Vaughan, M.; Ferrare, R. A.; Hostetler, C. A.; Rogers, R. R.; Burton, S. P.; Torres, O.; Remer, L. A.; Stier, P.; Schutgens, N.

    2014-12-01

    We describe a technique for combining CALIOP aerosol backscatter, MODIS spectral AOD (aerosol optical depth), and OMI AAOD (absorption aerosol optical depth) retrievals for the purpose of estimating full spectral sets of aerosol radiative properties, and ultimately for calculating the 3-D distribution of direct aerosol radiative forcing. We present results using one year of data collected in 2007 and show comparisons of the aerosol radiative property estimates to collocated AERONET retrievals. Use of the recently released MODIS Collection 6 data for aerosol optical depths derived with the dark target and deep blue algorithms has extended the coverage of the multi-sensor estimates towards higher latitudes. Initial calculations of seasonal clear-sky aerosol radiative forcing based on our multi-sensor aerosol retrievals compare well with over-ocean and top of the atmosphere IPCC-2007 model-based results, and with more recent assessments in the "Climate Change Science Program Report: Atmospheric Aerosol Properties and Climate Impacts" (2009). For the first time, we present comparisons of our multi-sensor aerosol direct radiative forcing estimates to values derived from a subset of models that participated in the latest AeroCom initiative. We discuss the major challenges that exist in extending our clear-sky results to all-sky conditions. On the basis of comparisons to suborbital measurements, we present some of the limitations of the MODIS and CALIOP retrievals in the presence of adjacent or underlying clouds. Strategies for meeting these challenges are discussed.

  6. Explaining the Diverse Response of the Ultra-relativistic Van Allen Radiation Belt to Solar Wind Forcing

    Science.gov (United States)

    Mann, I. R.; Ozeke, L.; Murphy, K. R.; Claudepierre, S. G.; Rae, J.; Milling, D. K.; Kale, A.; Baker, D. N.

    2017-12-01

    The NASA Van Allen Probes have opened a new window on the dynamics of ultra-relativistic electrons in the Van Allen radiation belts. Under different solar wind forcing the outer belt is seen to respond in a variety of apparently diverse and sometimes remarkable ways. For example, sometimes a third radiation belt is carved out (e.g., September 2012), or the belts can remain depleted for 10 days or more (September 2014). More usually there is a sequential response of a strong and sometimes rapid depletion followed by a re-energization, the latter increasing outer belt electron flux by orders of magnitude on hour timescales during some of the strongest storms of this solar cycle (e.g., March 2013, March 2015). Such dynamics also appear to be often bounded at low-L by an apparently impenetrable barrier at L 2.8 through which ultra-relativistic electrons do not penetrate. Many studies in the Van Allen Probes era have sought explanations for these apparently diverse features, often incorporating the effects from multiple plasma waves. In contrast, we show how this apparently diverse behaviour can instead be explained by one dominant process: ULF wave radial transport. Once ULF wave transport rates are accurately specified by observations, and coupled to the dynamical variation of the outer boundary condition at the edge of the outer belt, the observed diverse responses can all be explained. However, in order to get good agreement with observations, the modeling reveals the importance of still currently unexplained very fast loss in the main phase which results in an almost total extinction of the belts and decouples pre- and post-storm ultra-relativistic electron flux on hour timescales. Similarly, varying plasmasheet source populations are seen to be of critical importance such that near-tail dynamics play a crucial role in Van Allen belt dynamics. Nonetheless, simple models incorporating accurate transport rates derived directly from ULF wave measurements are shown to

  7. The use of Acoustic Radiation Force decorrelation-weighted pulse inversion (ADW-PI) for enhanced ultrasound contrast imaging

    Science.gov (United States)

    Herbst, Elizabeth; Unnikrishnan, Sunil; Wang, Shiying; Klibanov, Alexander L.; Hossack, John A.; Mauldin, F. William

    2016-01-01

    Objectives The use of ultrasound imaging for cancer diagnosis and screening can be enhanced with the use of molecularly targeted microbubbles. Nonlinear imaging strategies such as pulse inversion (PI) and “contrast pulse sequences” (CPS) can be used to differentiate microbubble signal, but often fail to suppress highly echogenic tissue interfaces. This failure results in false positive detection and potential misdiagnosis. In this study, a novel Acoustic Radiation Force (ARF) based approach was developed for superior microbubble signal detection. The feasibility of this technique, termed ARF-decorrelation-weighted PI (ADW-PI), was demonstrated in vivo using a subcutaneous mouse tumor model. Materials and Methods Tumors were implanted in the hindlimb of C57BL/6 mice by subcutaneous injection of MC38 cells. Lipid-shelled microbubbles were conjugated to anti-VEGFR2 antibody and administered via bolus injection. An image sequence using ARF pulses to generate microbubble motion was combined with PI imaging on a Verasonics Vantage programmable scanner. ADW-PI images were generated by combining PI images with inter-frame signal decorrelation data. For comparison, CPS images of the same mouse tumor were acquired using a Siemens Sequoia clinical scanner. Results Microbubble-bound regions in the tumor interior exhibited significantly higher signal decorrelation than static tissue (n = 9, p < 0.001). The application of ARF significantly increased microbubble signal decorrelation (n = 9, p < 0.01). Using these decorrelation measurements, ADW-PI imaging demonstrated significantly improved microbubble contrast-to-tissue ratio (CTR) when compared to corresponding CPS or PI images (n = 9, p < 0.001). CTR improved with ADW-PI by approximately 3 dB compared to PI images and 2 dB compared to CPS images. Conclusions Acoustic radiation force can be used to generate adherent microbubble signal decorrelation without microbubble bursting. When combined with pulse inversion

  8. Acoustic Radiation Force Impulse Elastography in Determining the Effects of Type 1 Diabetes on Pancreas and Kidney Elasticity in Children.

    Science.gov (United States)

    Sağlam, Dilek; Bilgici, Meltem Ceyhan; Kara, Cengiz; Yılmaz, Gülay Can; Çamlıdağ, İlkay

    2017-11-01

    The aim of this study is to determine the effects of type 1 diabetes on pancreas and kidney elasticity in children, using acoustic radiation force impulse ultrasound elastography. Sixty autoantibody-positive patients with type 1 diabetes (45% girls; mean [± SD] age, 11.7 ± 4.4 years; range, 1.9-19.3 years) admitted to the pediatric endocrinology outpatient clinic and 32 healthy children (50% girls; mean age, 10.2 ± 3.8 years; range, 2.1-17.3 years) were included in the study. Acoustic radiation force impulse elastography measurements were performed of the kidneys and pancreas in both groups. Body mass index, duration of diabetes, HbA1c levels, and insulin dosage of patients with type 1 diabetes were recorded. The mean shear-wave velocities of the pancreas were 0.99 ± 0.25 m/s in patients with type 1 diabetes and 1.09 ± 0.22 m/s in healthy control subjects; the difference was not significant (p = 0.08). The median shear-wave velocities of the right and left kidneys in patients with type 1 diabetes were 2.43 ± 0.29 and 2.47 ± 0.25 m/s, respectively. There were no significant differences in the shear-wave velocities of the right and left kidneys between the patients with type 1 diabetes and the healthy control subjects (p = 0.91 and p = 0.73, respectively). Correlation analysis showed no correlation between the shear-wave velocities of the pancreas and kidney versus HbA1c level, duration of diabetes, insulin dosage, height, weight, and body mass index of the patients with type 1 diabetes. The current study showed no significant difference in the shear-wave velocity of kidneys in children with type 1 diabetes with normoalbuminuria compared with the healthy control subjects. We also observed that the shear-wave velocity of the pancreas in children with type 1 diabetes and healthy control subjects did not differ significantly.

  9. Brown carbon aerosols from burning of boreal peatlands: microphysical properties, emission factors, and implications for direct radiative forcing

    Directory of Open Access Journals (Sweden)

    R. K. Chakrabarty

    2016-03-01

    Full Text Available The surface air warming over the Arctic has been almost twice as much as the global average in recent decades. In this region, unprecedented amounts of smoldering peat fires have been identified as a major emission source of climate-warming agents. While much is known about greenhouse gas emissions from these fires, there is a knowledge gap on the nature of particulate emissions and their potential role in atmospheric warming. Here, we show that aerosols emitted from burning of Alaskan and Siberian peatlands are predominantly brown carbon (BrC – a class of visible light-absorbing organic carbon (OC – with a negligible amount of black carbon content. The mean fuel-based emission factors for OC aerosols ranged from 3.8 to 16.6 g kg−1. Their mass absorption efficiencies were in the range of 0.2–0.8 m2 g−1 at 405 nm (violet and dropped sharply to 0.03–0.07 m2 g−1 at 532 nm (green, characterized by a mean Ångström exponent of  ≈  9. Electron microscopy images of the particles revealed their morphologies to be either single sphere or agglomerated “tar balls”. The shortwave top-of-atmosphere aerosol radiative forcing per unit optical depth under clear-sky conditions was estimated as a function of surface albedo. Only over bright surfaces with albedo greater than 0.6, such as snow cover and low-level clouds, the emitted aerosols could result in a net warming (positive forcing of the atmosphere.

  10. Chemical and climatic drivers of radiative forcing due to changes in stratospheric and tropospheric ozone over the 21st century

    Science.gov (United States)

    Banerjee, Antara; Maycock, Amanda C.; Pyle, John A.

    2018-02-01

    The ozone radiative forcings (RFs) resulting from projected changes in climate, ozone-depleting substances (ODSs), non-methane ozone precursor emissions and methane between the years 2000 and 2100 are calculated using simulations from the UM-UKCA chemistry-climate model (UK Met Office's Unified Model containing the United Kingdom Chemistry and Aerosols sub-model). Projected measures to improve air-quality through reductions in non-methane tropospheric ozone precursor emissions present a co-benefit for climate, with a net global mean ozone RF of -0.09 W m-2. This is opposed by a positive ozone RF of 0.05 W m-2 due to future decreases in ODSs, which is driven by an increase in tropospheric ozone through stratosphere-to-troposphere transport of air containing higher ozone amounts. An increase in methane abundance by more than a factor of 2 (as projected by the RCP8.5 scenario) is found to drive an ozone RF of 0.18 W m-2, which would greatly outweigh the climate benefits of non-methane tropospheric ozone precursor reductions. A small fraction (˜ 15 %) of the ozone RF due to the projected increase in methane results from increases in stratospheric ozone. The sign of the ozone RF due to future changes in climate (including the radiative effects of greenhouse gases, sea surface temperatures and sea ice changes) is shown to be dependent on the greenhouse gas emissions pathway, with a positive RF (0.05 W m-2) for RCP4.5 and a negative RF (-0.07 W m-2) for the RCP8.5 scenario. This dependence arises mainly from differences in the contribution to RF from stratospheric ozone changes. Considering the increases in tropopause height under climate change causes only small differences (≤ |0.02| W m-2) for the stratospheric, tropospheric and whole-atmosphere RFs.

  11. On Effective Radiative Forcing of Partial Internally and Externally Mixed Aerosols and Their Effects on Global Climate

    Science.gov (United States)

    Zhou, Chen; Zhang, Hua; Zhao, Shuyun; Li, Jiangnan

    2018-01-01

    The total effective radiative forcing (ERF) due to partial internally mixed (PIM) and externally mixed (EM) anthropogenic aerosols, as well as their climatic effects since the year of 1850, was evaluated and compared using the aerosol-climate online coupled model of BCC_AGCM2.0_CUACE/Aero. The influences of internal mixing (IM) on aerosol hygroscopicity parameter, optical properties, and concentration were considered. Generally, IM could markedly weaken the negative ERF and cooling effects of anthropogenic aerosols. The global annual mean ERF of EM anthropogenic aerosols from 1850 to 2010 was -1.87 W m-2, of which the aerosol-radiation interactive ERF (ERFari) and aerosol-cloud interactive ERF (ERFaci) were -0.49 and -1.38 W m-2, respectively. The global annual mean ERF due to PIM anthropogenic aerosols from 1850 to 2010 was -1.23 W m-2, with ERFari and ERFaci of -0.23 and -1.01 W m-2, respectively. The global annual mean surface temperature and water evaporation and precipitation were reduced by 1.74 K and 0.14 mm d-1 for EM scheme and 1.28 K and 0.11 mm d-1 for PIM scheme, respectively. However, the relative humidity near the surface was slightly increased for both mixing cases. The Intertropical Convergence Zone was southwardly shifted for both EM and PIM cases but was less southwardly shifted in PIM scheme due to the less reduction in atmospheric temperature in the midlatitude and low latitude of the Northern Hemisphere.

  12. Understanding the drivers of post-fire albedo and radiative forcing across Alaska and Canada: implications for management.

    Science.gov (United States)

    Potter, S.; Solvik, K.; Erb, A.; Goetz, S. J.; Johnstone, J. F.; Mack, M. C.; Randerson, J. T.; Roman, M. O.; Schaaf, C. L.; Turetsky, M. R.; Veraverbeke, S.; Wang, Z.; Rogers, B. M.

    2017-12-01

    Boreal forest dynamics including succession, composition, carbon cycling, and surface-atmosphere energy exchanges are largely driven by fire. In Alaska and Canada, burned area and fire frequency have increased since the 1970s, and are projected to continue increasing into the 21st century. In contrast to other biomes, alterations to surface albedo from fires in North American boreal forests are one of the primary feedbacks to climate. Understanding how altered fire regimes impact vegetation composition and energy budgets is therefore critical to forecasting regional and global climate change. High-severity fires cause winter and spring albedo to increase due to increased snow exposure and replacement of evergreen conifers by deciduous broadleaf trees. Although summer albedo decreases initially due to the deposition of black carbon and charred surfaces, it typically increases for several decades thereafter when younger and brighter deciduous trees dominate. The net effect of these albedo changes is expected to result in substantive radiative cooling, but there has been little research to examine how albedo trajectories differ spatially and temporally as a result of differences in burn severity, species composition, topography, climate and soil properties, and what the associated implications for future energy balances are. Here we investigate drivers of post-fire monthly albedo trajectories across Canada and Alaska using a new Collection V006 500 m MODIS daily blue-sky albedo product and historical fires from the Canadian and Alaskan National Fire Databases. The impacts of varying fuel type, landscape position, soils, climate, and burn severity on monthly albedo trajectories are explored using a Random Forest model. This information is then used to predict long-term monthly albedo and radiative forcing for fires that occurred during the MODIS era (2001-2012). We find that higher severity burns in denser forests and environmental conditions that promote either

  13. Estimation of shortwave direct aerosol radiative forcing at four locations on the Indo-Gangetic plains: Model results and ground measurement

    Science.gov (United States)

    Bibi, Humera; Alam, Khan; Bibi, Samina

    2017-08-01

    This study provides observational results of aerosol optical and radiative characteristics over four locations in IGP. Spectral variation of Aerosol Optical Depth (AOD), Single Scattering Albedo (SSA) and Asymmetry Parameter (AP) were analysed using AErosol RObotic NETwork (AERONET) data. The analysis revealed that coarse particles were dominant in summer and pre-monsoon, while fine particles were more pronounced in winter and post-monsoon. Furthermore, the spatio-temporal variations of Shortwave Direct Aerosol Radiative Forcing (SDARF) and Shortwave Direct Aerosol Radiative Forcing Efficiency (SDARFE) at the Top Of Atmosphere (TOA), SURface (SUR) and within ATMosphere (ATM) were calculated using SBDART model. The atmospheric Heating Rate (HR) associated with SDARFATM were also computed. It was observed that the monthly averaged SDARFTOA and SDARFSUR were found to be negative leading to positive SDARFATM during all the months over all sites. The increments in net atmospheric forcing lead to maximum HR in November-December and May. The seasonal analysis of SDARF revealed that SDARFTOA and SDARFSUR were negative during all seasons. The SW atmospheric absorption translates to highest atmospheric HR during summer over Karachi and during pre-monsoon over Lahore, Jaipur and Kanpur. Like SDARF, the monthly and seasonal variations of SDARFETOA and SDARFESUR were found to be negative, resulting in positive atmospheric forcing. Additionally, to compare the model estimated forcing against AERONET derived forcing, the regression analysis of AERONET-SBDART forcing were carried out. It was observed that SDARF at SUR and TOA showed relatively higher correlation over Lahore, moderate over Jaipur and Kanpur and lower over Karachi. Finally, the analysis of National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model revealed that air masses were arriving from multiple source locations.

  14. Acoustic radiation force impulse elastography of the liver. Can fat deposition in the liver affect the measurement of liver stiffness?

    International Nuclear Information System (INIS)

    Motosugi, Utaroh; Ichikawa, Tomoaki; Araki, Tsutomu; Niitsuma, Yoshibumi

    2011-01-01

    The aim of this study was to compare acoustic radiation force impulse (ARFI) results between livers with and without fat deposition. We studied 200 consecutive healthy individuals who underwent health checkups at our institution. The subjects were divided into three groups according to the echogenicity of the liver on ultrasonography (US) and the liver-spleen attenuation ratio index (LSR) on computed tomography: normal liver group (n=121, no evidence of bright liver on US and LSR >1); fatty liver group (n=46, bright liver on US and LSR 5 days a week (n=18) were excluded from the analysis. The velocities measured by ARFI in the normal and fatty liver groups were compared using the two one-sided test. The mean (SD) velocity measured in the normal and fatty liver groups were 1.03 (0.12) m/s and 1.02 (0.12) m/s, respectively. The ARFI results of the fatty liver group were similar to those of the normal liver group (P<0.0001). This study suggested that fat deposition in the liver does not affect the liver stiffness measurement determined by ARFI. (author)

  15. Changes in liver stiffness measurement using acoustic radiation force impulse elastography after antiviral therapy in patients with chronic hepatitis C.

    Directory of Open Access Journals (Sweden)

    Sheng-Hung Chen

    Full Text Available To compare on-treatment and off-treatment parameters acquired using acoustic radiation force impulse elastography, the Fibrosis-4 (FIB-4 index, and aspartate aminotransferase-to-platelet ratio index (APRI in patients with chronic hepatitis C (CHC.Patients received therapies based on pegylated interferon or direct-acting antiviral agents. The changes in paired patient parameters, including liver stiffness (LS values, the FIB-4 index, and APRI, from baseline to sustained virologic response (SVR visit (24 weeks after the end of treatment were compared. Multiple regression models were used to identify significant factors that explained the correlations with LS, FIB-4, and APRI values and SVR.A total of 256 patients were included, of which 219 (85.5% achieved SVR. The paired LS values declined significantly from baseline to SVR visit in all groups and subgroups except the nonresponder subgroup (n = 10. Body mass index (P = 0.0062 and baseline LS (P < 0.0001 were identified as independent factors that explained the LS declines. Likewise, the baseline FIB-4 (P < 0.0001 and APRI (P < 0.0001 values independently explained the declines in the FIB-4 index and APRI, respectively. Moreover, interleukin-28B polymorphisms, baseline LS, and rapid virologic response were identified as independent correlates with SVR.Paired LS measurements in patients treated for CHC exhibited significant declines comparable to those in FIB-4 and APRI values. These declines may have correlated with the resolution of necroinflammation. Baseline LS values predicted SVR.

  16.  Usefulness of acoustic radiation force impulse and fibrotest in liver fibrosis assessment after liver transplant.

    Science.gov (United States)

    Bignulin, Sara; Falleti, Edmondo; Cmet, Sara; Cappello, Dario; Cussigh, Annarosa; Lenisa, Ilaria; Dissegna, Denis; Pugliese, Fabio; Vivarelli, Cinzia; Fabris, Carlo; Fabris, Carlo; Toniutto, Pierluigi

    2016-01-01

     Background and rationale. Acoustic radiation force impulse (ARFI) is a non-invasive tool used in the evaluation of liver fibrosis in HCV positive immune-competent patients. This study aimed to assess the accuracy of ARFI in discriminating liver transplanted patients with different graft fibrosis severity and to verify whether ARFI, eventually combined with non-invasive biochemical tests, could spare liver biopsies. This prospective study included 51 HCV positive liver transplanted patients who consecutively underwent to annual liver biopsy concomitantly with ARFI and blood chemistry tests measurements needed to calculate several non-invasive liver fibrosis tests. Overall ARFI showed an AUC of 0.885 in discriminating between patients without or with significant fibrosis (Ishak score 0-2vs. 3-6). Using a cut-off of 1.365 m/s, ARFI possesses a negative predictive value of 100% in identifying patients without significant fibrosis. AUC for Fibrotest was 0.848 in discriminating patients with Ishak fibrosis score 0-2 vs. 3-6. The combined assessment of ARFI and Fibro-test did not improve the results obtained by ARFI alone. ARFI measurement in HCV positive liver transplanted patients can be considered an easy and accurate non-invasive tool in identify patients with a benign course of HCV recurrence.

  17. Acoustic radiation force impulse elastography for differentiation of benign and malignant thyroid nodules with concurrent Hashimoto's thyroiditis.

    Science.gov (United States)

    Liu, Bo-Ji; Xu, Hui-Xiong; Zhang, Yi-Feng; Xu, Jun-Mei; Li, Dan-Dan; Bo, Xiao-Wan; Li, Xiao-Long; Guo, Le-Hang; Xu, Xiao-Hong; Qu, Shen

    2015-03-01

    The purpose of the study was to explore the diagnostic performance of acoustic radiation force impulse (ARFI) elastography in differential diagnosis between benign and malignant thyroid nodules in patients with coexistent Hashimoto's thyroiditis (HT). A total of 141 pathological proven nodules in 141 HT patients (7 males and 134 females, mean age 50.1 years, range 23-75 years) received conventional ultrasound (US), elasticity imaging (EI) and ARFI elastography, including virtual touch tissue imaging (VTI) and virtual touch tissue quantification (VTQ), before surgery. Shear wave velocity (SWV) and SWV ratio were measured for each nodule on VTQ. The US, EI and ARFI elastography features were compared between benign and malignant nodules in HT patients. Receiver operating characteristic curve (ROC) analyses and area under curve (AUC) were performed to assess the diagnostic performance. Pathologically, 70 nodules were benign and 71 nodules were malignant. Significant differences were found between benign and malignant nodules in HT patients for EI (EI score) and ARFI (VTI grade and SWV) (all P value benign and malignant thyroid nodules in HT patients. The diagnostic performance of ARFI elastography is better than EI.

  18. Virtual touch tissue quantification of acoustic radiation force impulse: a new ultrasound elastic imaging in the diagnosis of thyroid nodules.

    Directory of Open Access Journals (Sweden)

    Yi-Feng Zhang

    Full Text Available OBJECTIVE: Virtual touch tissue quantification (VTQ of acoustic radiation force impulse (ARFI is a new quantitative technique to measure tissue stiffness. The study was aimed to assess the usefulness of VTQ in the diagnosis of thyroid nodules. METHODS: 173 pathologically proven thyroid nodules in 142 patients were included and all were examined by conventional ultrasound (US, conventional elasticity imaging (EI and VTQ of ARFI. The tissue stiffness for VTQ was expressed as shear wave velocity (SWV (m/s. Receiver-operating characteristic curve (ROC analyses were performed to assess the diagnostic performance. Intra- and inter-observer reproducibility of VTQ measurement was assessed. RESULTS: The SWVs of benign and malignant thyroid nodules were 2.34±1.17 m/s (range: 0.61-9.00 m/s and 4.82±2.53 m/s (range: 2.32-9.00 m/s respectively (P20 mm and lowest for those ≤10 mm. The correlation coefficients were 0.904 for intraobserver measurement and 0.864 for interobserver measurement. CONCLUSIONS: VTQ of ARFI provides quantitative and reproducible information about the tissue stiffness, which is useful for the differentiation between benign and malignant thyroid nodules. The diagnostic performance of VTQ is higher than that of conventional EI.

  19. The Impact of the Aerosol Direct Radiative Forcing on Deep Convection and Air Quality in the Pearl River Delta Region

    Science.gov (United States)

    Liu, Z.; Yim, Steve H. L.; Wang, C.; Lau, N. C.

    2018-05-01

    Literature has reported the remarkable aerosol impact on low-level cloud by direct radiative forcing (DRF). Impacts on middle-upper troposphere cloud are not yet fully understood, even though this knowledge is important for regions with a large spatial heterogeneity of emissions and aerosol concentration. We assess the aerosol DRF and its cloud response in June (with strong convection) in Pearl River Delta region for 2008-2012 at cloud-resolving scale using an air quality-climate coupled model. Aerosols suppress deep convection by increasing atmospheric stability leading to less evaporation from the ground. The relative humidity is reduced in middle-upper troposphere due to induced reduction in both evaporation from the ground and upward motion. The cloud reduction offsets 20% of the aerosol DRF. The weaker vertical mixing further increases surface aerosol concentration by up to 2.90 μg/m3. These findings indicate the aerosol DRF impact on deep convection and in turn regional air quality.

  20. Acoustic radiation force on a sphere in standing and quasi-standing zero-order Bessel beam tweezers

    International Nuclear Information System (INIS)

    Mitri, F.G.

    2008-01-01

    Starting from the exact acoustic scattering from a sphere immersed in an ideal fluid and centered along the propagation axis of a standing or quasi-standing zero-order Bessel beam, explicit partial-wave representations for the radiation force are derived. A standing or a quasi-standing acoustic field is the result of propagating two equal or unequal amplitude zero-order Bessel beams, respectively, along the same axis but in opposite sense. The Bessel beam is characterized by the half-cone angle β of its plane wave components, such that β = 0 represents a plane wave. It is assumed here that the half-cone angle β for each of the counter-propagating acoustic Bessel beams is equal. Fluid, elastic and viscoelastic spheres immersed in water are treated as examples. Results indicate the capability of manipulating spherical targets based on their mechanical and acoustical properties. This condition provides an impetus for further designing acoustic tweezers operating with standing or quasi-standing Bessel acoustic waves. Potential applications include particle manipulation in micro-fluidic lab-on-chips as well as in reduced gravity environments

  1. Impact of forced convective radiative heat and mass transfer mechanisms on 3D Carreau nanofluid: A numerical study

    Science.gov (United States)

    Khan, M.; Irfan, M.; Khan, W. A.

    2017-12-01

    Nanoliquids retain remarkable features that have fascinated various researchers owing to their utilization in nanoscience and nanotechnology. We will present a mathematical relation for 3D forced convective heat and mass transfer mechanism of a Carreau nanoliquid over a bidirectional stretched surface. Additionally, the features of heat source/sink and nonlinear thermal radiation are considered for the 3D Carreau nanoliquid. The governing nonlinear PDEs are established and altered into a set of nonlinear ODEs by utilizing a suitable conversion. A numerical approach, namely the bvp4c is adopted to resolve the resultant equations. The achieved outcomes are schemed and conferred in detail for somatic parameters. It is realized that amassed values of Brownian motion parameter Nb lead to enhance the temperature of the Carreau nanoliquid while quite conflicting behavior is being noticed for the concentration of the Carreau nanoliquid. Moreover, it is also noted that the influence of heat source δ > 0 is relatively antithetic to heat sink δ communication with these results.

  2. Air-coupled acoustic radiation force for non-contact generation of broadband mechanical waves in soft media

    Energy Technology Data Exchange (ETDEWEB)

    Ambroziński, Łukasz [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); AGH University of Science and Technology, Krakow 30059 (Poland); Pelivanov, Ivan, E-mail: ivanp3@uw.edu [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Faculty of Physics, Moscow State University, Moscow 119991 (Russian Federation); Song, Shaozhen; Yoon, Soon Joon; Gao, Liang; O' Donnell, Matthew [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Li, David [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Department of Chemical Engineering, University of Washington Seattle, Washington 98195 (United States); Shen, Tueng T.; Wang, Ruikang K. [Department of Bioengineering, University of Washington, Seattle, Washington 98195 (United States); Department of Ophthalmology, University of Washington, Seattle, Washington 98104 (United States)

    2016-07-25

    A non-contact method for efficient, non-invasive excitation of mechanical waves in soft media is proposed, in which we focus an ultrasound (US) signal through air onto the surface of a medium under study. The US wave reflected from the air/medium interface provides radiation force to the medium surface that launches a transient mechanical wave in the transverse (lateral) direction. The type of mechanical wave is determined by boundary conditions. To prove this concept, a home-made 1 MHz piezo-ceramic transducer with a matching layer to air sends a chirped US signal centered at 1 MHz to a 1.6 mm thick gelatin phantom mimicking soft biological tissue. A phase-sensitive (PhS)-optical coherence tomography system is used to track/image the mechanical wave. The reconstructed transient displacement of the mechanical wave in space and time demonstrates highly efficient generation, thus offering great promise for non-contact, non-invasive characterization of soft media, in general, and for elasticity measurements in delicate soft tissues and organs in bio-medicine, in particular.

  3. Diagnostic value of coustic radiation force impulse for BI-RADS category 4 breast lesions of different sizes.

    Science.gov (United States)

    Wu, Rong

    2018-04-14

    To determine the diagnostic value of combined conventional ultrasound (US) and acoustic radiation force impulse (ARFI) imaging for the differential diagnosis of BI-RADS category 4 breast lesions of different sizes. From April 2013 to January 2015, 283 patients (with a total of 292 breast lesions) who underwent US and ARFI examination were included in this retrospective study. The SWV for the lesion and adjacent normal breast tissue were measured and the SWV ratio was calculated. VTI grade was also assessed. The lesions were separated into three groups on the basis of size, and two combinations of ARFI parameters (SWV + VTI and SWV ratio + VTI) were applied to reassess the BI-RADS categories. Diagnoses were confirmed by pathological examination after biopsy or surgery. ROC analysis was performed to assess the diagnostic efficiency of each method. The Z test was used to compare the difference between AUC of the two methods. Significant improvement was seen in the diagnostic performance of US with the use of the ARFI parameters SWV + VTI (77/179 [43.0%] of BI-RADS category 4A breast lesions were downgraded) and SWV ratio + VTI (64/179 [35.8%] of BI-RADS category 4A breast lesions were downgraded, including two malignant cases that were misdiagnosed as benign) (P BI-RADS category 4 breast lesions. The combination of SWV ratio + VTI can improve BI-RADS classification of small lesions (<10 mm size).

  4. Assessing hepatic fibrosis: comparing the intravoxel incoherent motion in MRI with acoustic radiation force impulse imaging in US

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chih-Horng; Liang, Po-Chin; Shih, Tiffany Ting-Fang [National Taiwan University Hospital, Department of Medical Imaging, Taipei (China); National Taiwan University College of Medicine, Department of Radiology, Taipei (China); Ho, Ming-Chih; Hu, Rey-Heng; Lai, Hong-Shiee [National Taiwan University Hospital and College of Medicine, Department of Surgery, Taipei (China); Jeng, Yung-Ming [National Taiwan University Hospital and College of Medicine, Department of Pathology, Taipei (China)

    2015-12-15

    This study compared the diagnostic performance of intravoxel incoherent motion (IVIM) in magnetic resonance imaging (MRI) and acoustic radiation force impulse imaging (ARFI) in ultrasound (US) for liver fibrosis (LF) evaluation. A total of 49 patients scheduled for liver surgery were recruited. LF in the non-tumorous liver parenchyma at the right lobe was estimated using a slow diffusion coefficient, fast diffusion coefficient (D{sub fast}), perfusion fraction (f) of the IVIM parameters, the total apparent diffusion coefficient of conventional diffusion-weighted imaging and the shear wave velocity (Vs) of ARFI. LF was graded using the Metavir scoring system on histological examination. The Spearman rank correlation coefficient for correlation and analysis of variance was used for determining difference. The diagnostic performance was compared using receiver operating characteristic curve analysis. LF exhibited significant correlation with the three parameters D{sub fast}, f, and Vs (r = -0.528, -0.337, and 0.481, respectively, P < 0.05). The D{sub fast} values in the F4 group were significantly lower than those in the F0, F1 and F2 groups. D{sub fast} exhibited a non-inferior performance for diagnosing all fibrosis grades compared with that of Vs. Both IVIM and ARFI provide reliable estimations for the noninvasive assessment of LF. (orig.)

  5. Combination of elastography and tissue quantification using the acoustic radiation force impulse (ARFI) technology for differential diagnosis of breast masses.

    Science.gov (United States)

    Tozaki, Mitsuhiro; Isobe, Sachiko; Sakamoto, Masaaki

    2012-10-01

    We evaluated the diagnostic performance of elastography and tissue quantification using acoustic radiation force impulse (ARFI) technology for differential diagnosis of breast masses. There were 161 mass lesions. First, lesion correspondence on ARFI elastographic images to those on the B-mode images was evaluated: no findings on ARFI images (pattern 1), lesions that were bright inside (pattern 2), lesions that were dark inside (pattern 4), lesions that contained both bright and dark areas (pattern 3). In addition, pattern 4 was subdivided into 4a (dark area same as B-mode lesion) and 4b (dark area larger than lesion). Next, shear wave velocity (SWV) was measured using virtual touch tissue quantification. There were 13 pattern 1 lesions and five pattern 2 lesions; all of these lesions were benign, whereas all pattern 4b lesions (n = 43) were malignant. When the value of 3.59 m/s was chosen as the cutoff value, the combination of elastography and tissue quantification showed 91 % (83-91) sensitivity, 93 % (65-70) specificity, and 92 % (148-161) accuracy. The combination of elastography and tissue quantification is thought to be a promising ultrasound technique for differential diagnosis of breast-mass lesions.

  6. A sensitivity study on modeling black carbon in snow and its radiative forcing over the Arctic and Northern China

    International Nuclear Information System (INIS)

    Qian, Yun; Wang, Hailong; Rasch, Philip J; Zhang, Rudong; Flanner, Mark G

    2014-01-01

    Black carbon in snow (BCS) simulated in the Community Atmosphere Model (CAM5) is evaluated against measurements over Northern China and the Arctic, and its sensitivity to atmospheric deposition and two parameters that affect post-depositional enrichment is explored. Improvements in atmospheric BC transport and deposition significantly reduce the biases (by a factor of two) in the estimation of BCS concentration over both Northern China and the Arctic. Further sensitivity simulations using the improved CAM5 indicate that the melt-water scavenging efficiency (MSE) parameter plays an important role in regulating BC concentrations in the Arctic through the post-depositional enrichment, which not only drastically changes the amplitude but also shifts the seasonal cycle of the BCS concentration and its radiative forcing in the Arctic. The impact of the snow aging scaling factor (SAF) on BCS shows more complex latitudinal and seasonal dependence, and overall impact of SAF is much smaller than that of MSE. The improvements of BC transport and deposition in CAM5 have a stronger influence on BCS than perturbations of the two snow model parameters in Northern China. (letters)

  7. A Sensitivity Study on Modeling Black Carbon in Snow and its Radiative Forcing over the Arctic and Northern China

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Yun; Wang, Hailong; Zhang, Rudong; Flanner, M. G.; Rasch, Philip J.

    2014-06-02

    Black carbon in snow (BCS) simulated in the Community Atmosphere Model (CAM5) is evaluated against measurements over Northern China and the Arctic, and its sensitivity to atmospheric deposition and two parameters that affect post-depositional enrichment is explored. The BCS concentration is overestimated (underestimated) by a factor of two in Northern China (Arctic) in the default model, but agreement with observations is good over both regions in the simulation with improvements in BC transport and deposition. Sensitivity studies indicate that uncertainty in the melt-water scavenging efficiency (MSE) parameter substantially affects BCS and its radiative forcing (by a factor of 2-7) in the Arctic through post-depositional enrichment. The MSE parameter has a relatively small effect on the magnitude of BCS seasonal cycle but can alter its phase in Northern China. The impact of the snow aging scaling factor (SAF) on BCS, partly through the post-depositional enrichment effect, shows more complex latitudinal and seasonal dependence. Similar to MSE, SAF affects more significantly the magnitude (phase) of BCS season cycle over the Arctic (Northern China). While uncertainty associated with the representation of BC transport and deposition processes in CAM5 is more important than that associated with the two snow model parameters in Northern China, the two uncertainties have comparable effect in the Arctic.

  8. Understanding the Asian summer monsoon response to greenhouse warming: the relative roles of direct radiative forcing and sea surface temperature change

    Science.gov (United States)

    Li, Xiaoqiong; Ting, Mingfang

    2017-10-01

    Future hydroclimate projections from state-of-the-art climate models show large uncertainty and model spread, particularly in the tropics and over the monsoon regions. The precipitation and circulation responses to rising greenhouse gases involve a fast component associated with direct radiative forcing and a slow component associated with sea surface temperature (SST) warming; the relative importance of the two may contribute to model discrepancies. In this study, regional hydroclimate responses to greenhouse warming are assessed using output from coupled general circulation models in the Coupled Model Intercomparison Project-Phase 5 (CMIP5) and idealized atmospheric general circulation model experiments from the Atmosphere Model Intercomparison Project. The thermodynamic and dynamic mechanisms causing the rainfall changes are examined using moisture budget analysis. Results show that direct radiative forcing and SST change exert significantly different responses both over land and ocean. For most part of the Asian monsoon region, the summertime rainfall changes are dominated by the direct CO2 radiative effect through enhanced monsoon circulation. The response to SST warming shows a larger model spread compared to direct radiative forcing, possibly due to the cancellation between the thermodynamical and dynamical components. While the thermodynamical response of the Asian monsoon is robust across the models, there is a lack of consensus for the dynamical response among the models and weak multi-model mean responses in the CMIP5 ensemble, which may be related to the multiple physical processes evolving on different time scales.

  9. Chemical and climatic drivers of radiative forcing due to changes in stratospheric and tropospheric ozone over the 21st century

    Directory of Open Access Journals (Sweden)

    A. Banerjee

    2018-02-01

    Full Text Available The ozone radiative forcings (RFs resulting from projected changes in climate, ozone-depleting substances (ODSs, non-methane ozone precursor emissions and methane between the years 2000 and 2100 are calculated using simulations from the UM-UKCA chemistry–climate model (UK Met Office's Unified Model containing the United Kingdom Chemistry and Aerosols sub-model. Projected measures to improve air-quality through reductions in non-methane tropospheric ozone precursor emissions present a co-benefit for climate, with a net global mean ozone RF of −0.09 W m−2. This is opposed by a positive ozone RF of 0.05 W m−2 due to future decreases in ODSs, which is driven by an increase in tropospheric ozone through stratosphere-to-troposphere transport of air containing higher ozone amounts. An increase in methane abundance by more than a factor of 2 (as projected by the RCP8.5 scenario is found to drive an ozone RF of 0.18 W m−2, which would greatly outweigh the climate benefits of non-methane tropospheric ozone precursor reductions. A small fraction (∼ 15 % of the ozone RF due to the projected increase in methane results from increases in stratospheric ozone. The sign of the ozone RF due to future changes in climate (including the radiative effects of greenhouse gases, sea surface temperatures and sea ice changes is shown to be dependent on the greenhouse gas emissions pathway, with a positive RF (0.05 W m−2 for RCP4.5 and a negative RF (−0.07 W m−2 for the RCP8.5 scenario. This dependence arises mainly from differences in the contribution to RF from stratospheric ozone changes. Considering the increases in tropopause height under climate change causes only small differences (≤ |0.02| W m−2 for the stratospheric, tropospheric and whole-atmosphere RFs.

  10. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP

    Directory of Open Access Journals (Sweden)

    D. S. Stevenson

    2013-03-01

    Full Text Available Ozone (O3 from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP has been used to calculate tropospheric ozone radiative forcings (RFs. All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750 to present-day (2010 tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%, nitrogen oxides (31 ± 9%, carbon monoxide (15 ± 3% and non-methane volatile organic compounds (9 ± 2%; earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m−2; relative to 1750 for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5 of 350, 420, 370 and 460 (in 2030, and 200, 300, 280 and 600 (in 2100. Models show some coherent responses of ozone to climate change

  11. Usefulness of acoustic radiation force impulse elastography in the differential diagnosis of benign and malignant solid pancreatic lesions

    Energy Technology Data Exchange (ETDEWEB)

    Park, Min Kyoung; Jo, Jeong Hyun; Kwon, Hee Jin; Cho, Jin Han; Oh, Jong Young; Noh, Myung Hwan; Nam, Kyung Jin [Dong-A University College of Medicine, Busan (Korea, Republic of)

    2014-03-15

    The aim of this study was to evaluate the tissue stiffness of solid pancreatic lesions by using acoustic radiation force impulse (ARFI) elastography to differentiate benign from malignant pancreatic lesions. ARFI elastography was performed in 26 patients who had 27 focal solid pancreatic lesions, including 8 benign lesions (mass-forming pancreatitis, 5; autoimmune pancreatitis, 3) and 19 malignant lesions (pancreatic adenocarcinoma, 16; metastasis from colorectal cancer, 2; malignant neuroendocrine tumor, 1). On the elastographic images of virtual touch tissue imaging (VTI), the echogenicity of the mass was categorized on a 5-grade scale. On the elastographic image of virtual touch tissue quantification (VTQ), the shear wave velocities (SWVs) of the lesion and surrounding parenchyma were measured. On the VTI images, the mean echogenicity score of the malignant lesions (3.7±1.0) was higher than that of the benign lesions (3.1±0.4; P=0.023). On the VTQ images, there were no statistical differences in the mean SWV between the benign (2.4±1.1 m/sec) and malignant (3.3±1.0 m/sec) lesions (P=0.101). However, the mean SWV difference values between the lesion and background parenchyma of the malignant lesions (1.5±0.8 m/sec) were higher than those of the benign lesions (0.4±0.3 m/sec; P=0.011). ARFI elastography can determine the relative stiffness between a lesion and the background pancreatic parenchyma using VTI and VTQ, which is helpful in the differentiation between benign and malignant solid pancreatic lesions.

  12. Estimation of radiative forcing and chore length of shallow convective clouds (SCC) based on broadband pyranometer measurement network

    Science.gov (United States)

    Shi, H.

    2017-12-01

    We presented a method to identify and calculate cloud radiative forcing (CRF) and horizontal chore length (L) of shallow convective clouds (SCC) using a network of 9 broadband pyranometers. The analyzing data was collected from the SCC campaign during two years summers (2015 2016) at Baiqi site over Inner Mongolia grassland. The network of pyranometers was operated across a spatial domain covering 42.16-42.30° N and 114.83-114.98° E. The SCC detection method was verified by observer reports and cameras, which showed that the detection method and human observations were in agreement about 75 %. The differences between the SCC detection method and human observations can be responsible for following factors: 1) small or dissipating clouds can be neglected for the value of 1 min of temporal resolution of pyranometer; 2) human observation recorded weather conditions four times every day; 3) SCC was indistinguishable from coexistence of SCC and Cirrus (Ci); 4) the SCC detection method is weighted toward clouds crossing the sun's path, while the human observer can view clouds over the entire sky. The deviation of L can be attributed to two factors: 1) the accuracy of wind speed at height of SCC and the ratio of horizontal and vertical length play a key role in determine values of L; 2) the effect of variance of solar zenith angle can be negligible. The downwelling shortwave CRF of SCC was -134.1 Wm-2. The average value of L of SCC was 1129 m. Besides, the distribution of normalized cloud chore length agreed well with power-law fit.

  13. Age-related changes in liver, kidney, and spleen stiffness in healthy children measured with acoustic radiation force impulse imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Mi-Jung, E-mail: mjl1213@yuhs.ac [Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Yonsei University, College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Kim, Myung-Joon, E-mail: mjkim@yuhs.ac [Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Yonsei University, College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Han, Kyung Hwa, E-mail: khhan@yuhs.ac [Biostatistics Collaboration Unit, Yonsei University, College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Yoon, Choon Sik, E-mail: yooncs58@yuhs.ac [Department of Radiology, Gangnam Severance Hospital, Yonsei University, College of Medicine, 211 Unjoo-ro, Gangnam-gu, Seoul (Korea, Republic of)

    2013-06-15

    Objectives: To evaluate the feasibility and age-related changes of shear wave velocity (SWV) in normal livers, kidneys, and spleens of children using acoustic radiation force impulse (ARFI) imaging. Materials and methods: Healthy pediatric volunteers prospectively underwent abdominal ultrasonography and ARFI. The subjects were divided into three groups according to age: group 1: <5 years old; group 2: 5–10 years old; and group 3: >10 years old. The SWV was measured using a 4–9 MHz linear probe for group 1 and a 1–4 MHz convex probe for groups 2 and 3. Three valid SWV measurements were acquired for each organ. Results: Two hundred and two children (92 male, 110 female) with an average age of 8.1 years (±4.7) were included in this study and had a successful measurement rate of 97% (196/202). The mean SWVs were 1.12 m/s for the liver, 2.19 m/s for the right kidney, 2.33 m/s for the left kidney, and 2.25 m/s for the spleen. The SWVs for the right and left kidneys, and the spleen showed age-related changes in all children (p < 0.001). And the SWVs for the kidneys increased with age in group 1, and those for the liver changed with age in group 3. Conclusions: ARFI measurements are feasible for solid abdominal organs in children using high or low frequency probes. The mean ARFI SWV for the kidneys increased according to age in children less than 5 years of age and in the liver, it changed with age in children over 10.

  14. Greenhouse impact due to the use of combustible fuels: life cycle viewpoint and relative radiative forcing commitment.

    Science.gov (United States)

    Kirkinen, Johanna; Palosuo, Taru; Holmgren, Kristina; Savolainen, Ilkka

    2008-09-01

    Extensive information on the greenhouse impacts of various human actions is important in developing effective climate change mitigation strategies. The greenhouse impacts of combustible fuels consist not only of combustion emissions but also of emissions from the fuel production chain and possible effects on the ecosystem carbon storages. It is important to be able to assess the combined, total effect of these different emissions and to express the results in a comprehensive way. In this study, a new concept called relative radiative forcing commitment (RRFC) is presented and applied to depict the greenhouse impact of some combustible fuels currently used in Finland. RRFC is a ratio that accounts for the energy absorbed in the Earth system due to changes in greenhouse gas concentrations (production and combustion of fuel) compared to the energy released in the combustion of fuel. RRFC can also be expressed as a function of time in order to give a dynamic cumulative picture on the caused effect. Varying time horizons can be studied separately, as is the case when studying the effects of different climate policies on varying time scales. The RRFC for coal for 100 years is about 170, which means that in 100 years 170 times more energy is absorbed in the atmosphere due to the emissions of coal combustion activity than is released in combustion itself. RRFC values of the other studied fuel production chains varied from about 30 (forest residues fuel) to 190 (peat fuel) for the 100-year study period. The length of the studied time horizon had an impact on the RRFC values and, to some extent, on the relative positions of various fuels.

  15. The importance of acoustic radiation force impulse (ARFI) elastography in the diagnosis and clinical course of acute pancreatitis.

    Science.gov (United States)

    Kaya, Muhsin; Değirmenci, Serdar; Göya, Cemil; Tuncel, Elif Tuba; Uçmak, Feyzullah; Kaplan, Mehmet Ali

    2018-05-01

    Acute pancreatitis (AP) is characterized by acute inflammation of the pancreas and it has a highly variable clinical course. The aim of our study was to evaluate the value of acoustic radiation force impulse (ARFI) elastography in the diagnosis and clinical course of AP. Consecutive patients with a diagnosis of AP (patients group) and healthy subject (control group) were prospectively enrolled to the study. Demographic features and clinical, laboratory, and radiological data were recorded. Virtual Touch Tissue Quantification (VTQ) was used to implement ARFI elastography. The tissue elasticity is proportional to the square of the wave velocity (SWV). A total of 108 patients (age, 57±1.8 y) and 79 healthy subjects (age, 53.6±1.81 y) were included in the study. There were 100 (92.5%) edematous and 8 (7.4%) necrotizing AP. The mean SWV was significantly higher in the patient group than in the control group (2.43±0.08 vs. 1.27±0.025 m/s, p < 0.001). There was not significant difference between patient and control group regarding age and gender. SWV cutoff value of 1.63 m/s was associated with 100% sensitivity and 98% specificity for the diagnosis of AP. There was not significant difference between patients with and without complications and patients with edematous and necrotizing AP regarding mean SWV value. There was also not significant correlation between mean SWV value and age, mean length of hospital stay, and mean amylase level. ARFI elastography may be a feasible method for the diagnosis of AP, but it has no value for the prediction of clinical course of AP.

  16. Usefulness of percutaneous elastography by acoustic radiation force impulse for the non-invasive diagnosis of chronic pancreatitis

    Directory of Open Access Journals (Sweden)

    Camilo Julio Llamoza-Torres

    Full Text Available Objective: To determine the accuracy of the acoustic radiation force impulse (ARFI technique for the diagnosis of chronic pancreatitis. Materials and methods: We present an observational, single-center study that included patients with suspected chronic pancreatitis in the period between October 2012 and September 2015 who underwent endoscopic ultrasound (EUS and were classified according to the standard and Rosemont criteria. The same group of patients was assessed by the ARFI technology using ACUSON S2000™ equipment with Virtual Touch™ Quantification software for the assessment of pancreatic stiffness by obtaining the shear wave velocity (SWV in the head, body and tail of the pancreas. Data were analyzed using ANOVA and nonparametric correlation methods. Diagnostic accuracy was obtained by analyzing receiver operating characteristic (ROC curve. Results: A total of thirty-three patients were studied (45.5% women; mean age was 58.3 ± 11.8 years. Seventeen with a diagnosis of chronic pancreatitis and sixteen classified as normal according to standard criteria. A significant difference was detected between the means of SWV in pancreatic body of patients without (SWV: 1.27 m/s and with chronic pancreatitis (SWV 1.57 m/s, p = 0.037. The area under the ROC curve was 71.3% (95% CI 0.532-0.895 and the accuracy of ARFI for diagnosing chronic pancreatitis was 69.7% for a SWV of 1.4 m/s in the pancreatic body. The SWV means in head (r = 0.421, p < 0.05 and body (r = 0.455, p < 0.05 of the pancreas showed a significant correlation with the number of EUS criteria for chronic pancreatitis. Conclusion: Quantification of pancreatic stiffness with ARFI elastography technique has proven to be useful for the non-invasive diagnosis of chronic pancreatitis.

  17. Shear wave velocity measurements using acoustic radiation force impulse in young children with normal kidneys versus hydronephrotic kidneys

    Energy Technology Data Exchange (ETDEWEB)

    Shon, Beom Seok; Kim, Myung Joon; Han, Sang Won; Im, Young Jae; Lee, Mi Jung [Severance Children' s Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2014-04-15

    To measure shear wave velocities (SWVs) by acoustic radiation force impulse (ARFI) ultrasound elastography in normal kidneys and in hydronephrotic kidneys in young children and to compare SWVs between the hydronephrosis grades. This study was approved by an institutional review board, and informed consent was obtained from the parents of all the children included. Children under the age of 24 months were prospectively enrolled. Hydronephrosis grade was evaluated on ultrasonography, and three valid ARFI measurements were attempted using a high-frequency transducer for both kidneys. Hydronephrosis was graded from 0 to 4, and high-grade hydronephrosis was defined as grades 3 and 4. Fifty-one children underwent ARFI measurements, and three valid measurements for both kidneys were obtained in 96% (49/51) of the patients. Nineteen children (38.8%) had no hydronephrosis. Twenty-three children (46.9%) had unilateral hydronephrosis, and seven children (14.3%) had bilateral hydronephrosis. Seven children had ureteropelvic junction obstruction (UPJO). Median SWVs in kidneys with high-grade hydronephrosis (2.02 m/sec) were higher than those in normal kidneys (1.75 m/sec; P=0.027). However, the presence of UPJO did not influence the median SWVs in hydronephrotic kidneys (P=0.362). Obtaining ARFI measurements of the kidney is feasible in young children with median SWVs of 1.75 m/sec in normal kidneys. Median SWVs increased in high-grade hydronephrotic kidneys but were not different between hydronephrotic kidneys with and without UPJO.

  18. Shear wave velocity measurements using acoustic radiation force impulse in young children with normal kidneys versus hydronephrotic kidneys

    International Nuclear Information System (INIS)

    Shon, Beom Seok; Kim, Myung Joon; Han, Sang Won; Im, Young Jae; Lee, Mi Jung

    2014-01-01

    To measure shear wave velocities (SWVs) by acoustic radiation force impulse (ARFI) ultrasound elastography in normal kidneys and in hydronephrotic kidneys in young children and to compare SWVs between the hydronephrosis grades. This study was approved by an institutional review board, and informed consent was obtained from the parents of all the children included. Children under the age of 24 months were prospectively enrolled. Hydronephrosis grade was evaluated on ultrasonography, and three valid ARFI measurements were attempted using a high-frequency transducer for both kidneys. Hydronephrosis was graded from 0 to 4, and high-grade hydronephrosis was defined as grades 3 and 4. Fifty-one children underwent ARFI measurements, and three valid measurements for both kidneys were obtained in 96% (49/51) of the patients. Nineteen children (38.8%) had no hydronephrosis. Twenty-three children (46.9%) had unilateral hydronephrosis, and seven children (14.3%) had bilateral hydronephrosis. Seven children had ureteropelvic junction obstruction (UPJO). Median SWVs in kidneys with high-grade hydronephrosis (2.02 m/sec) were higher than those in normal kidneys (1.75 m/sec; P=0.027). However, the presence of UPJO did not influence the median SWVs in hydronephrotic kidneys (P=0.362). Obtaining ARFI measurements of the kidney is feasible in young children with median SWVs of 1.75 m/sec in normal kidneys. Median SWVs increased in high-grade hydronephrotic kidneys but were not different between hydronephrotic kidneys with and without UPJO.

  19. Acoustic radiation force impulse imaging with Virtual Touch™ tissue quantification: mean shear wave velocity of malignant and benign breast masses.

    Science.gov (United States)

    Wojcinski, Sebastian; Brandhorst, Kathrin; Sadigh, Gelareh; Hillemanns, Peter; Degenhardt, Friedrich

    2013-01-01

    Acoustic radiation force impulse imaging (ARFI) with Virtual Touch™ tissue quantification (VTTQ) enables the determination of shear wave velocity (SWV) in meters per second (m/s). The aim of our study was to describe the mean SWV in normal breast tissue and various breast masses. We performed measurements of SWV with ARFI VTTQ in 145 breast masses (57 malignant, 88 benign) and in the adjacent breast parenchyma and adipose tissue. The mean SWV as well as the rate of successful measurements were analyzed. The difference between adipose tissue and parenchyma was statistically significant (3.05 versus 3.65 m/s) (P breast masses, numerous measurements exceeded the upper limit of possible measurement (≥9.10 m/s, indicated as "X.XX m/s"). Nevertheless, the difference between the malignant and benign masses was statistically significant (8.38 ± 1.99 m/s versus 5.39 ± 2.95 m/s) (P < 0.001). The best diagnostic accuracy (75.9%) was achieved when the cutoff point for malignancy was set to 9.10 m/s in ARFI VTTQ. This implies that the SWV was regarded as suspicious when the upper limit of possible measurement was exceeded and the machine returned the value X.XX m/s. In conclusion, ARFI VTTQ is a feasible method for measurement of SWV in a region of interest. Furthermore, we propose the event of a highly elevated SWV as a significant criterion for malignancy. However, the method is technically not yet fully developed, and the problem of unsuccessful measurements must still be solved.

  20. Acoustic Radiation Force Impulse Elastography for fibrosis evaluation in patients with chronic hepatitis C: An international multicenter study

    Energy Technology Data Exchange (ETDEWEB)

    Sporea, Ioan, E-mail: isporea@umft.ro [Department of Gastroenterology and Hepatology, University of Medicine and Pharmacy Timisoara (Romania); Bota, Simona, E-mail: bota_simona1982@yahoo.com [Department of Gastroenterology and Hepatology, University of Medicine and Pharmacy Timisoara (Romania); Peck-Radosavljevic, Markus, E-mail: markus.peck@meduniwien.ac.at [Internal Medicine III, Division of Gastroenterology and Hepatology, Medical University of Vienna (Austria); Sirli, Roxana, E-mail: roxanasirli@gmail.com [Department of Gastroenterology and Hepatology, University of Medicine and Pharmacy Timisoara (Romania); Tanaka, Hironori, E-mail: hironori@hyo-med.ac.jp [Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya (Japan); Iijima, Hiroko, E-mail: hiroko.iijima@nifty.com [Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya (Japan); Badea, Radu, E-mail: rbadea2003@yahoo.com [3rd Medical Clinic, University of Medicine, Cluj Napoca (Romania); Lupsor, Monica, E-mail: monica.lupsor@umfcluj.ro [3rd Medical Clinic, University of Medicine, Cluj Napoca (Romania); Fierbinteanu-Braticevici, Carmen, E-mail: cfierbinteanu@yahoo.com [2nd Medical Clinic and Gastroenterology, University Hospital, Bucharest (Romania); Petrisor, Ana, E-mail: ana1petrisor@yahoo.com [2nd Medical Clinic and Gastroenterology, University Hospital, Bucharest (Romania); Saito, Hidetsugu, E-mail: hidetsugusaito@gmail.com [Department of Internal Medicine, School of Medicine, Keio University, Tokyo (Japan); Ebinuma, Hirotoshi, E-mail: ebinuma@a5.keio.jp [Department of Internal Medicine, School of Medicine, Keio University, Tokyo (Japan); Friedrich-Rust, Mireen, E-mail: Mireen.Friedrich-Rust@kgu.de [Department of Internal Medicine, J.W. Goethe University, Frankfurt/Main (Germany); Sarrazin, Christoph, E-mail: sarrazin@em.uni-frankfurt.de [Department of Internal Medicine, J.W. Goethe University, Frankfurt/Main (Germany); and others

    2012-12-15

    Aim: The aim of this international multicenter study was to evaluate the reliability of Acoustic Radiation Force Impulse (ARFI) elastography for predicting fibrosis severity, in patients with chronic hepatitis C. Patients and methods: We compared ARFI to liver biopsy (LB) in 914 patients (10 centers, 5 countries) with chronic hepatitis C. In each patient LB (evaluated according to the METAVIR score) and ARFI measurements were performed (median of 5–10 valid measurements, expressed in meters/second – m/s). In 400 from the 914 patients, transient elastography (TE) was also performed (median of 6–10 valid measurements, expressed in kiloPascals – kPa). Results: Valid ARFI measurements were obtained in 911 (99.6%) of 914 cases. On LB 61 cases (6.7%) had F0, 241 (26.4%) had F1, 202 (22.1%) had F2, 187 (20.4%) had F3, and 223 (24.4%) had F4 fibrosis. A highly significant correlation (r = 0.654) was found between ARFI measurements and fibrosis (p < 0.0001). The predictive values of ARFI for various stages of fibrosis were: F ≥ 1 – cut-off > 1.19 m/s (AUROC = 0.779), F ≥ 2 – cut-off > 1.33 m/s (AUROC = 0.792), F ≥ 3 – cut-off > 1.43 m/s (AUROC = 0.829), F = 4 – cut-off > 1.55 m/s (AUROC = 0.842). The correlation with histological fibrosis was not significantly different for TE in comparison with ARFI elastography: r = 0.728 vs. 0.689, p = 0.28. TE was better than ARFI for predicting the presence of liver cirrhosis (p = 0.01) and fibrosis (F ≥ 1, METAVIR) (p = 0.01). Conclusion: ARFI elastography is a reliable method for predicting fibrosis severity in chronic hepatitis C patients.

  1. Problems of organization of interaction of administrative bodies and the forces engaged in liquidation of after-effects of radiation accident

    International Nuclear Information System (INIS)

    Popov, A.P.; Perevezentsev, A.M.

    1995-01-01

    The paper defines the main problems arising in connection with organization of interaction of the administrative bodies and the forces involved in liquidation of after-effects of radiation accident. It is demonstrated that in order to increase the efficiency of interaction of the administrative bodies of various levels it is necessary to make it automatic. The paper revealed the meaning of the levels of relationship between various automatic systems. 4 refs

  2. Fog-induced variations in aerosol optical and physical properties over the Indo-Gangetic Basin and impact to aerosol radiative forcing

    Directory of Open Access Journals (Sweden)

    S. K. Das

    2008-06-01

    Full Text Available A detailed study on the changes in aerosol physical and optical properties during fog events were made in December 2004 at Hissar (29.13° N, 75.70° E, a city located in the Indo-Gangetic basin. The visible aerosol optical depth was relatively low (0.3 during the initial days, which, however, increased (0.86 as the month progressed. The increasing aerosol amount, the decreasing surface temperature and a higher relative humidity condition were found favoring the formation of fog. The fog event is also found to alter the aerosol size distribution. An increase in the number concentration of the nucleation mode (radius<0.1 μm particles, along with a decrease in the mode radius showed the formation of freshly nucleated aerosols. In the case of accumulation mode (0.1 μmradiative forcing. The top of the atmosphere forcing is found to increase during foggy days due to large backscattering of radiation back to space. It is also shown that during foggy days, as the day progresses the RH value decreases, which reduces the forcing value while the increasing solar elevation increases the forcing value. Thus the fog event which prolongs longer into the daytime has a stronger effect on the diurnally averaged aerosol radiative forcing than those events which are confined only to the early morning hours.

  3. Fog-induced variations in aerosol optical and physical properties over the Indo-Gangetic Basin and impact to aerosol radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.K.; Misra, A. [Physical Research Lab., Ahmedabad (India); Jayaraman, A. [National Atmospheric Research Lab., Gadanki (India)

    2008-07-01

    A detailed study on the changes in aerosol physical and optical properties during fog events were made in December 2004 at Hissar (29.13 N, 75.70 E), a city located in the Indo-Gangetic basin. The visible aerosol optical depth was relatively low (0.3) during the initial days, which, however, increased (0.86) as the month progressed. The increasing aerosol amount, the decreasing surface temperature and a higher relative humidity condition were found favoring the formation of fog. The fog event is also found to alter the aerosol size distribution. An increase in the number concentration of the nucleation mode (radius<0.1 {mu}m) particles, along with a decrease in the mode radius showed the formation of freshly nucleated aerosols. In the case of accumulation mode (0.1 {mu}mradiative forcing. The top of the atmosphere forcing is found to increase during foggy days due to large backscattering of radiation back to space. It is also shown that during foggy days, as the day progresses the RH value decreases, which reduces the forcing value while the increasing solar elevation increases the forcing value. Thus the fog event which prolongs longer into the daytime has a stronger effect on the diurnally averaged aerosol radiative forcing than those events which are confined only to the early morning hours. (orig.)

  4. Multi-Model Simulations of Aerosol and Ozone Radiative Forcing Due to Anthropogenic Emission Changes During the Period 1990-2015

    Science.gov (United States)

    Myhre, Gunnar; Aas, Wenche; Ribu, Cherian; Collins, William; Faluvegi, Gregory S.; Flanner, Mark; Forster, Piers; Hodnebrog, Oivind; Klimont, Zbigniew; Lund, Marianne T.

    2017-01-01

    Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990-2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g. 1 to 3 percent per year in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990-2015 period increased by 0.17 plus or minus 0.08 watts per square meter, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5 (Intergovernmental Panel on Climate Change Fifth Assessment Report). The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the new emission inventory compared to that used in the IPCC analysis, and higher black carbon emissions.

  5. Impact of mountain pine beetle outbreaks on forest albedo and radiative forcing, as derived from Moderate Resolution Imaging Spectroradiometer, Rocky Mountains, USA

    Science.gov (United States)

    Vanderhoof, M.; Williams, C. A.; Ghimire, B.; Rogan, J.

    2013-12-01

    pine beetle (Dendroctonus ponderosae) outbreaks in North America are widespread and have potentially large-scale impacts on albedo and associated radiative forcing. Mountain pine beetle outbreaks in Colorado and southern Wyoming have resulted in persistent and significant increases in both winter albedo (change peaked 10 years post outbreak at 0.06 ± 0.01 and 0.05 ± 0.01, in lodgepole pine (Pinus contorta) and ponderosa pine (Pinus ponderosa) stands, respectively) and spring albedo (change peaked 10 years post outbreak at 0.06 ± 0.01 and 0.04 ± 0.01, in lodgepole pine and ponderosa pine stands, respectively). Instantaneous top-of-atmosphere radiative forcing peaked for both lodgepole pine and ponderosa pine stands in winter at 10 years post outbreak at -1.7 ± 0.2 W m-2 and -1.4 ± 0.2 W m-2, respectively. The persistent increase in albedo with time since mountain pine beetle disturbance combined with the continued progression of the attack across the landscape from 1994-2011 resulted in an exponential increase in winter and annual radiative cooling (MW) over time. In 2011 the rate of radiative forcing within the study area reached -982.7 ± 139.0 MW, -269.8 ± 38.2 MW, -31.1 ± 4.4 MW, and -147.8 ± 20.9 MW in winter, spring, summer, and fall, respectively. An increase in radiative cooling has the potential to decrease sensible and/or latent heat flux by reducing available energy. Such changes could affect current mountain pine beetle outbreaks which are influenced by climatic conditions.

  6. A numerical study of three-dimensional flame propagation over thin solids in purely forced concurrent flow including gas-phase radiation

    Science.gov (United States)

    Feier, Ioan I., Jr.

    The effect of flame radiation on concurrent-flow flame spread over a thin solid sample of finite width in a low-speed wind tunnel is modeled using three-dimensional full Navier-Stokes equations and three-dimensional flame radiation transfer equations. The formulation includes the conservation of mass, momentum, energy, and species: fuel vapor, oxygen, carbon dioxide and water vapor. The SN discrete ordinates method is used to solve the radiation transfer equation with a mean absorption coefficient kappa = Ckappa p, where kappap is the Planck mean absorption coefficient of the gas mixture. The varying parameter C has a value between 0 and 1; C represents the strength of flame radiation. In addition, the solid fuel absorptivity alpha is varied to ascertain the effect of flame radiation heat feedback to the solid. The flow tunnel modeled has a dimension of 10x10x30 cm, the solid fuel has a width of 6-cm with two 1-cm inert strips as edges. Incoming forced flow velocity (5 cm/s) of 21% oxygen is assumed. For comparison with the three-dimensional results, corresponding two-dimensional computations are also performed. Detailed spatial flame profiles, solid surface profiles, and heat fluxes are presented. Increasing the flame radiation strength decreases the flame length. Although flame radiation provides an additional heat transfer mechanism to preheat the solid, it is insufficient to offset the decreased convective heating due to the shorter flame; the net effect is a slower spread rate. The percentage of unreacted fuel vapor that escapes from the flame is under 2%. It is theorized that some of the pyrolyzed fuel vapor diffuses sideway and reacts at the flame edges. A radiative energy balance is analyzed also. Flame radiative feedback to the solid plays a more important role in two-dimensional flames. With high solid fuel absorptivity, a peak in the flame spread rate occurs at an intermediate value of flame radiation strength---due to the competition between two

  7. Atmospheric aerosol radiative forcing over a semi-continental location Tripura in North-East India: Model results and ground observations.

    Science.gov (United States)

    Dhar, Pranab; De, Barin Kumar; Banik, Trisanu; Gogoi, Mukunda M; Babu, S Suresh; Guha, Anirban

    2017-02-15

    Northeast India (NEI) is located within the boundary of the great Himalayas in the north and the Bay of Bengal (BoB) in the southwest, experiences the mixed influence of the westerly dust advection from the Indian desert, anthropogenic aerosols from the highly polluted Indo-Gangetic Plains (IGP) and marine aerosols from BoB. The present study deals with the estimation and characterization of aerosol radiative forcing over a semi-continental site Tripura, which is a strategic location in the western part of NEI having close proximity to the outflow of the IGP. Continuous long term measurements of aerosol black carbon (BC) mass concentrations and columnar aerosol optical depth (AOD) are used for the estimation of aerosol radiative forcing in each monthly time scale. The study revealed that the surface forcing due to aerosols was higher during both winter and pre-monsoon seasons, having comparable values of 32W/m 2 and 33.45W/m 2 respectively. The atmospheric forcing was also higher during these months due to increased columnar aerosol loadings (higher AOD ~0.71) shared by abundant BC concentrations (SSA ~0.7); while atmospheric forcing decreased in monsoon due to reduced magnitude of BC (SSA ~0.94 in July) as well as columnar AOD. The top of the atmosphere (TOA) forcing is positive in pre-monsoon and monsoon months with the highest positive value of 3.78W/m 2 in June 2012. The results are discussed in light of seasonal source impact and transport pathways from adjacent regions. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Present and potential future contributions of sulfate, black and organic carbon aerosols from China to global air quality, premature mortality and radiative forcing

    Science.gov (United States)

    Saikawa, Eri; Naik, Vaishali; Horowitz, Larry W.; Liu, Junfeng; Mauzerall, Denise L.

    Aerosols are harmful to human health and have both direct and indirect effects on climate. China is a major contributor to global emissions of sulfur dioxide (SO 2), a sulfate (SO 42-) precursor, organic carbon (OC), and black carbon (BC) aerosols. Although increasingly examined, the effect of present and potential future levels of these emissions on global premature mortality and climate change has not been well quantified. Through both direct radiative effects and indirect effects on clouds, SO 42- and OC exert negative radiative forcing (cooling) while BC exerts positive forcing (warming). We analyze the effect of China's emissions of SO 2, SO 42-, OC and BC in 2000 and for three emission scenarios in 2030 on global surface aerosol concentrations, premature mortality, and radiative forcing (RF). Using global models of chemical transport (MOZART-2) and radiative transfer (GFDL RTM), and combining simulation results with gridded population data, mortality rates, and concentration-response relationships from the epidemiological literature, we estimate the contribution of Chinese aerosols to global annual premature mortality and to RF in 2000 and 2030. In 2000, we estimate these aerosols cause approximately 470 000 premature deaths in China and an additional 30 000 deaths globally. In 2030, aggressive emission controls lead to a 50% reduction in premature deaths from the 2000 level to 240 000 in China and 10 000 elsewhere, while under a high emissions scenario premature deaths increase 50% from the 2000 level to 720 000 in China and to 40 000 elsewhere. Because the negative RF from SO 42- and OC is larger than the positive forcing from BC, Chinese aerosols lead to global net direct RF of -74 mW m -2 in 2000 and between -15 and -97 mW m -2 in 2030 depending on the emissions scenario. Our analysis indicates that increased effort to reduce greenhouse gases is essential to address climate change as China's anticipated reduction of aerosols will result in the

  9. Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2injection studied with the LMDZ-S3A model

    Science.gov (United States)

    Kleinschmitt, Christoph; Boucher, Olivier; Platt, Ulrich

    2018-02-01

    The enhancement of the stratospheric sulfate aerosol layer has been proposed as a method of geoengineering to abate global warming. Previous modelling studies found that stratospheric aerosol geoengineering (SAG) could effectively compensate for the warming by greenhouse gases on the global scale, but also that the achievable cooling effect per sulfur mass unit, i.e. the forcing efficiency, decreases with increasing injection rate. In this study we use the atmospheric general circulation model LMDZ with the sectional aerosol module S3A to determine how the forcing efficiency depends on the injected amount of SO2, the injection height, and the spatio-temporal pattern of injection. We find that the forcing efficiency may decrease more drastically for larger SO2 injections than previously estimated. As a result, the net instantaneous radiative forcing does not exceed the limit of -2 W m-2 for continuous equatorial SO2 injections and it decreases (in absolute value) for injection rates larger than 20 Tg S yr-1. In contrast to other studies, the net radiative forcing in our experiments is fairly constant with injection height (in a range 17 to 23 km) for a given amount of SO2 injected. Also, spreading the SO2 injections between 30° S and 30° N or injecting only seasonally from varying latitudes does not result in a significantly larger (i.e. more negative) radiative forcing. Other key characteristics of our simulations include a consequent stratospheric heating, caused by the absorption of solar and infrared radiation by the aerosol, and changes in stratospheric dynamics, with a collapse of the quasi-biennial oscillation at larger injection rates, which has impacts on the resulting spatial aerosol distribution, size, and optical properties. But it has to be noted that the complexity and uncertainty of stratospheric processes cause considerable disagreement among different modelling studies of stratospheric aerosol geoengineering. This may be addressed through detailed

  10. Assessment of 1D and 3D model simulated radiation flux based on surface measurements and estimation of aerosol forcing and their climatological aspects

    Science.gov (United States)

    Subba, T.; Gogoi, M. M.; Pathak, B.; Ajay, P.; Bhuyan, P. K.; Solmon, F.

    2018-05-01

    Ground reaching solar radiation flux was simulated using a 1-dimensional radiative transfer (SBDART) and a 3-dimensional regional climate (RegCM 4.4) model and their seasonality against simultaneous surface measurements carried out using a CNR4 net Radiometer over a sub-Himalayan foothill site of south-east Asia was assessed for the period from March 2013-January 2015. The model simulated incoming fluxes showed a very good correlation with the measured values with correlation coefficient R2 0.97. The mean bias errors between these two varied from -40 W m-2 to +7 W m-2 with an overestimation of 2-3% by SBDART and an underestimation of 2-9% by RegCM. Collocated measurements of the optical parameters of aerosols indicated a reduction in atmospheric transmission path by 20% due to aerosol load in the atmosphere when compared with the aerosol free atmospheric condition. Estimation of aerosol radiative forcing efficiency (ARFE) indicated that the presence of black carbon (BC, 10-15%) led to a surface dimming by -26.14 W m-2 τ-1 and a potential atmospheric forcing of +43.04 W m-2 τ-1. BC alone is responsible for >70% influence with a major role in building up of forcing efficiency of +55.69 W m-2 τ-1 (composite) in the atmosphere. On the other hand, the scattering due to aerosols enhance the outgoing radiation at the top of the atmosphere (ARFETOA -12.60 W m-2 ω-1), the absence of which would have resulted in ARFETOA of +16.91 W m-2 τ-1 (due to BC alone). As a result, 3/4 of the radiation absorption in the atmosphere is ascribed to the presence of BC. This translated to an atmospheric heating rate of 1.0 K day-1, with 0.3 K day-1 heating over the elevated regions (2-4 km) of the atmosphere, especially during pre-monsoon season. Comparison of the satellite (MODIS) derived and ground based estimates of surface albedo showed seasonal difference in their magnitudes (R2 0.98 during retreating monsoon and winter; 0.65 during pre-monsoon and monsoon), indicating that the

  11. Quantifying enhancement in aerosol radiative forcing during ‘extreme aerosol days’ in summer at Delhi National Capital Region, India

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sumant [School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Dey, Sagnik [Centre for Atmospheric Sciences, IIT Delhi, New Delhi 110016 (India); Srivastava, Arun [School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

    2016-04-15

    Changes in aerosol characteristics (spectral aerosol optical depth, AOD and composition) are examined during the transition from ‘relatively clean’ to ‘extreme’ aerosol days in the summer of 2012 at Delhi National Capital Region (NCR), India. AOD smaller than 0.54 (i.e. 12-year mean AOD − 1σ) represents ‘relatively clean’ days in Delhi during the summer. ‘Extreme’ days are defined by the condition when AOD{sub 0.5} exceeds 12-year mean AOD + 1 standard deviation (σ). Mean (± 1σ) AOD increases to 1.2 ± 0.12 along with a decrease of Angstrom Exponent from 0.54 ± 0.09 to 0.22 ± 0.12 during the ‘extreme’ days. Aerosol composition is inferred by fixing the number concentrations of various individual species through iterative tweaking when simulated (following Mie theory) AOD spectrum matches with the measured one. Contribution of coarse mode dust to aerosol mass increased from 76.8% (relatively clean) to 96.8% (extreme events), while the corresponding contributions to AOD{sub 0.5} increased from 35.0% to 70.8%. Spectrally increasing single scattering albedo (SSA) and CALIPSO aerosol sub-type information support the dominant presence of dust during the ‘extreme’ aerosol days. Aerosol direct radiative forcing (ADRF) at the top-of-the-atmosphere increases from 21.2 W m{sup −2} (relatively clean) to 56.6 W m{sup −2} (extreme), while the corresponding change in surface ADRF is from − 99.5 W m{sup −2} to − 153.5 W m{sup −2}. Coarse mode dust contributes 60.3% of the observed surface ADRF during the ‘extreme’ days. On the contrary, 0.4% mass fraction of black carbon (BC) translates into 13.1% contribution to AOD{sub 0.5} and 33.5% to surface ADRF during the ‘extreme’ days. The atmospheric heating rate increased by 75.1% from 1.7 K/day to 2.96 K/day during the ‘extreme’ days. - Graphical abstract: Deviation (in %) of aerosol properties from ‘relatively clean’ days to ‘extreme’ aerosol days. - Highlights:

  12. Dust in Snow in the Colorado River Basin: Spatial Variability in Dust Concentrations, Radiative Forcing, and Snowmelt Rates

    Science.gov (United States)

    Skiles, M.; Painter, T.; Deems, J. S.; Landry, C.; Bryant, A.

    2012-12-01

    Since the disturbance of the western US that began with the Anglo settlement in the mid 19th century, the mountain snow cover of the Colorado River Basin (CRB) has been subject to five-fold greater dust loading. This dust deposition accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. We have previously quantified the impacts of dust in snow using a 6-year record of dust concentration and energy balance fluxes at the alpine and subalpine towers in the Senator Beck Basin Study Area (SBBSA), San Juan Mountains in southwestern Colorado, USA. Dust loading exhibited interannual variability, and end of year dust concentrations were not necessarily related to the number of dust deposition events. Radiative forcing enhanced springtime melt by 21 to 51 days with the magnitude of advanced loss being linearly related to total dust concentration at the end of snow cover. To expand our understanding of dust on snow deposition patterns we utilize collections of dust concentration at the Colorado Dust on Snow (CODOS) study sites, established in 2009 along the western side of the CRB, to assess spatial variability in dust loading. In situ sampling of dust stratigraphy and concentration occurs twice each season, once over peak snow water equivalent (15 April), and again during melt (15 May). Dust loading occurs at all sites; dust concentrations are always higher in May, vary between sites, and the highest and lowest dust years were 2009 and 2012, respectively. In the absence of regular sampling and energy balance instrumentation these sites do not allow us to quantify the advanced melt due to dust. To facilitate this a new energy balance site, Grand Mesa Study plot (GMSP), was established for water year 2010 in west central Colorado, 150 km north of SBBSA. Back trajectories indicate similar Colorado Plateau dust sources at both SBBSA and GMSP, yet GMSP exhibits slightly lower dust

  13. Columnar aerosol characteristics and radiative forcing over the Doon Valley in the Shivalik range of northwestern Himalayas.

    Science.gov (United States)

    Dumka, U C; Saheb, Shaik Darga; Kaskaoutis, D G; Kant, Yogesh; Mitra, D

    2016-12-01

    Spectral aerosol optical depth (AOD) measurements obtained from multi-wavelength radiometer under cloudless conditions over Doon Valley, in the foothills of the western Himalayas, are analysed during the period January 2007 to December 2012. High AOD values of 0.46 ± 0.08 and 0.52 ± 0.1 at 500 nm, along with low values of Ångström exponent (0.49 ± 0.01 and 0.44 ± 0.03) during spring (March-May) and summer (June-August), respectively, suggest a flat AOD spectrum indicative of coarse-mode aerosol abundance compared with winter (December-February) and autumn (September-November), which are mostly dominated by fine aerosols from urban/industrial emissions and biomass burning. The columnar size distributions (CSD) retrieved from the King's inversion of spectral AOD exhibit bimodal size patterns during spring and autumn, while combinations of the power-law and unimodal distributions better simulate the retrieved CSDs during winter and summer. High values of extinction coefficient near the surface (∼0.8-1.0 km -1 at 532 nm) and a steep decreasing gradient above are observed via CALIPSO profiles in autumn and winter, while spring and summer exhibit elevated aerosol layers between ∼1.5 and 3.5 km due to the presence of dust. The particle depolarisation ratio shows a slight increasing trend with altitude, with higher values in spring and summer indicative of non-spherical particles of dust origin. The aerosol-climate implications are evaluated via the aerosol radiative forcing (ARF), which is estimated via the synergy of OPAC and SBDART models. On the monthly basis, the ARF values range from ∼ -30 to -90 W m -2 at the surface, while aerosols cause an overall cooling effect at the top of atmosphere (approx. -5 to -15 W m -2 ). The atmospheric heating via aerosol absorption results in heating rates of 1.2-1.6 K day -1 during March-June, which may contribute to changes in monsoon circulation over northern India and the Himalayas.

  14. Quantifying enhancement in aerosol radiative forcing during 'extreme aerosol days' in summer at Delhi National Capital Region, India.

    Science.gov (United States)

    Kumar, Sumant; Dey, Sagnik; Srivastava, Arun

    2016-04-15

    Changes in aerosol characteristics (spectral aerosol optical depth, AOD and composition) are examined during the transition from 'relatively clean' to 'extreme' aerosol days in the summer of 2012 at Delhi National Capital Region (NCR), India. AOD smaller than 0.54 (i.e. 12-year mean AOD-1σ) represents 'relatively clean' days in Delhi during the summer. 'Extreme' days are defined by the condition when AOD0.5 exceeds 12-year mean AOD+1 standard deviation (σ). Mean (±1σ) AOD increases to 1.2±0.12 along with a decrease of Angstrom Exponent from 0.54±0.09 to 0.22±0.12 during the 'extreme' days. Aerosol composition is inferred by fixing the number concentrations of various individual species through iterative tweaking when simulated (following Mie theory) AOD spectrum matches with the measured one. Contribution of coarse mode dust to aerosol mass increased from 76.8% (relatively clean) to 96.8% (extreme events), while the corresponding contributions to AOD0.5 increased from 35.0% to 70.8%. Spectrally increasing single scattering albedo (SSA) and CALIPSO aerosol sub-type information support the dominant presence of dust during the 'extreme' aerosol days. Aerosol direct radiative forcing (ADRF) at the top-of-the-atmosphere increases from 21.2Wm(-2) (relatively clean) to 56.6Wm(-2) (extreme), while the corresponding change in surface ADRF is from -99.5Wm(-2) to -153.5Wm(-2). Coarse mode dust contributes 60.3% of the observed surface ADRF during the 'extreme' days. On the contrary, 0.4% mass fraction of black carbon (BC) translates into 13.1% contribution to AOD0.5 and 33.5% to surface ADRF during the 'extreme' days. The atmospheric heating rate increased by 75.1% from 1.7K/day to 2.96K/day during the 'extreme' days. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Does standoff material affect acoustic radiation force impulse elastography? A preclinical study of a modified elastography phantom

    Directory of Open Access Journals (Sweden)

    Katharina Hollerieth

    2018-04-01

    Full Text Available Purpose This study was conducted to determine the influence of standoff material on acoustic radiation force impulse (ARFI measurements in an elasticity phantom by using two different probes. Methods Using ARFI elastography, 10 observers measured the shear wave velocity (SWV, m/sec in different lesions of an elasticity phantom with a convex 4C1 probe and a linear 9L4 probe. The experimental setup was expanded by the use of an interposed piece of porcine muscle as standoff material. The probe pressure on the phantom was registered. Results Faulty ARFI measurements occurred more often when quantifying the hardest lesion (74.0 kPa 4.97 m/sec by the 9L4 probe with the porcine muscle as a standoff material interposed between the probe and the phantom. The success rate for ARFI measurements in these series was 52.4%, compared with 99.5% in the other series. The SWV values measured with the 9L4 probe were significantly higher (3.33±1.39 m/sec vs. 2.60±0.74 m/sec, P<0.001 in the group without muscle and were closer to the reference value than those measured with the 4C1 probe (0.25±0.23 m/sec vs. 0.85±1.21 m/sec, P<0.001 in the same group. The SWV values measured when using the muscle as a standoff material were lower than those without the muscle (significant for 9L4, P=0.040. The deviation from the reference value and the variance increased significantly with the 9L4 probe if the muscle was in situ (B=0.27, P=0.004 and B=0.32, P<0.001. In our study, the pressure exerted by the operator had no effect on the SWV values. Conclusion The presence of porcine muscle acting as a standoff material influenced the occurrence of failed measurements as well as the variance and the accuracy of the measured values. The linear high-frequency probe was particularly affected.

  16. Acoustic radiation force impulse imaging with Virtual Touch™ tissue quantification: mean shear wave velocity of malignant and benign breast masses

    Directory of Open Access Journals (Sweden)

    Wojcinski S

    2013-09-01

    Full Text Available Sebastian Wojcinski,1 Kathrin Brandhorst,2 Gelareh Sadigh,3 Peter Hillemanns,1 Friedrich Degenhardt2 1Department of Obstetrics and Gynecology, Hannover Medical School, Hannover, Germany; 2Department of Obstetrics and Gynecology, Franziskus Hospital, Bielefeld, Germany; 3Department of Radiology, Emory University, Atlanta, GA, USA Abstract: Acoustic radiation force impulse imaging (ARFI with Virtual Touch™ tissue quantification (VTTQ enables the determination of shear wave velocity (SWV in meters per second (m/s. The aim of our study was to describe the mean SWV in normal breast tissue and various breast masses. We performed measurements of SWV with ARFI VTTQ in 145 breast masses (57 malignant, 88 benign and in the adjacent breast parenchyma and adipose tissue. The mean SWV as well as the rate of successful measurements were analyzed. The difference between adipose tissue and parenchyma was statistically significant (3.05 versus 3.65 m/s (P < 0.001. Focusing on breast masses, numerous measurements exceeded the upper limit of possible measurement (≥9.10 m/s, indicated as "X.XX m/s". Nevertheless, the difference between the malignant and benign masses was statistically significant (8.38 ± 1.99 m/s versus 5.39 ± 2.95 m/s (P < 0.001. The best diagnostic accuracy (75.9% was achieved when the cutoff point for malignancy was set to 9.10 m/s in ARFI VTTQ. This implies that the SWV was regarded as suspicious when the upper limit of possible measurement was exceeded and the machine returned the value X.XX m/s. In conclusion, ARFI VTTQ is a feasible method for measurement of SWV in a region of interest. Furthermore, we propose the event of a highly elevated SWV as a significant criterion for malignancy. However, the method is technically not yet fully developed, and the problem of unsuccessful measurements must still be solved. Keywords: ARFI VTTQ, elastography, ultrasound, breast imaging

  17. Veterinary applications of ionising radiation HERCA Task Force on Veterinary Applications. Main results of the Questionnaire 'National regulatory requirements with regard to veterinary medical applications of ionising radiation' and conclusions of the TF

    International Nuclear Information System (INIS)

    Van Bladel, Lodewijk; Berlamont, Jolien; Michalczak, Herbert; Balogh, Lajos; Peremans, Kathelijne

    2013-11-01

    In the fall of 2012, the subject of radiation protection in veterinary medicine was raised during the meeting of the HERCA Board. Issues with regard to this subject had been brought to the attention of HERCA by the European College of Veterinary Diagnostic Imaging (ECVDI). In October 2012, the Board decided to charge a small Task Force (TF) to further explore the issues in this field. This TF drew up a questionnaire which looked at the general radiation protection regulatory requirements in veterinary medicine applications of ionizing radiation. The results of this study showed large differences in the requirements applicable in the HERCA member countries. The TF also noticed the increasing use of more complex imaging procedures and of different radio-therapeutic modalities, which may imply greater risks of exposure of humans to ionising radiation. These results were presented during the HERCA Board meeting in Berlin, Germany and on which the Board decided to establish a Working Group on veterinary applications of ionising radiations (WG Vet). The main results of the Questionnaire 'National regulatory requirements with regard to veterinary medicine applications of ionising radiation' is attached in Appendix

  18. Interagency task force on the health effects of ionizing radiation: report of the work group on care and benefits

    International Nuclear Information System (INIS)

    1979-06-01

    The report examines existing systems for providing care and benefits to persons who may have been injured by radiation exposure and recommends additional guidelines for handling radiation-related claims. The benefits systems examined are Veterans' benefits, Federal Employees Compensation Act, Longshoremen's and Harbor Workers' Compensation Act, State Workers' Compensation programs, Government and private 'back-up' program, Social Security Disability Insurance (Medicare), Supplemental Security Income (Medicaid), private health insurance, government hospitals, and remedies available under the judicial system. The report recommends that the Federal Government develop guidelines to determine the likelihood of a causal relationship between a person's illness and his exposure to radiation; that Federal compensation programs and State programs develop criteria for deciding radiation exposure claims, based on those guidelines; that a national registry of radiation workers be established to maintain individual radiation exposure records; and that the Federal Government annually compile compensation claims based on radiation exposure. Appendixes list those groups of people most likely to be exposed to radiation, and the benefits available under the various compensation programs listed above

  19. Axial acoustic radiation force on rigid oblate and prolate spheroids in Bessel vortex beams of progressive, standing and quasi-standing waves.

    Science.gov (United States)

    Mitri, F G

    2017-02-01

    The analysis using the partial-wave series expansion (PWSE) method in spherical coordinates is extended to evaluate the acoustic radiation force experienced by rigid oblate and prolate spheroids centered on the axis of wave propagation of high-order Bessel vortex beams composed of progressive, standing and quasi-standing waves, respectively. A coupled system of linear equations is derived after applying the Neumann boundary condition for an immovable surface in a non-viscous fluid, and solved numerically by matrix inversion after performing a single numerical integration procedure. The system of linear equations depends on the partial-wave index n and the order of the Bessel vortex beam m using truncated but converging PWSEs in the least-squares sense. Numerical results for the radiation force function, which is the radiation force per unit energy density and unit cross-sectional surface, are computed with particular emphasis on the amplitude ratio describing the transition from the progressive to the pure standing waves cases, the aspect ratio (i.e., the ratio of the major axis over the minor axis of the spheroid), the half-cone angle and order of the Bessel vortex beam, as well as the dimensionless size parameter. A generalized expression for the radiation force function is derived for cases encompassing the progressive, standing and quasi-standing waves of Bessel vortex beams. This expression can be reduced to other types of beams/waves such as the zeroth-order Bessel non-vortex beam or the infinite plane wave case by appropriate selection of the beam parameters. The results for progressive waves reveal a tractor beam behavior, characterized by the emergence of an attractive pulling force acting in opposite direction of wave propagation. Moreover, the transition to the quasi-standing and pure standing wave cases shows the acoustical tweezers behavior in dual-beam Bessel vortex beams. Applications in acoustic levitation, particle manipulation and acousto

  20. Simulating black carbon and dust and their radiative forcing in seasonal snow: a case study over North China with field campaign measurements

    Science.gov (United States)

    Zhao, C.; Hu, Z.; Qian, Y.; Leung, L. Ruby; Huang, J.; Huang, M.; Jin, J.; Flanner, M. G.; Zhang, R.; Wang, H.; Yan, H.; Lu, Z.; Streets, D. G.

    2014-10-01

    A state-of-the-art regional model, the Weather Research and Forecasting (WRF) model (Skamarock et al., 2008) coupled with a chemistry component (Chem) (Grell et al., 2005), is coupled with the snow, ice, and aerosol radiative (SNICAR) model that includes the most sophisticated representation of snow metamorphism processes available for climate study. The coupled model is used to simulate black carbon (BC) and dust concentrations and their radiative forcing in seasonal snow over North China in January-February of 2010, with extensive field measurements used to evaluate the model performance. In general, the model simulated spatial variability of BC and dust mass concentrations in the top snow layer (hereafter BCS and DSTS, respectively) are consistent with observations. The model generally moderately underestimates BCS in the clean regions but significantly overestimates BCS in some polluted regions. Most model results fall within the uncertainty ranges of observations. The simulated BCS and DSTS are highest with > 5000 ng g-1 and up to 5 mg g-1, respectively, over the source regions and reduce to dust in the atmosphere. This study represents an effort in using a regional modeling framework to simulate BC and dust and their direct radiative forcing in snowpack. Although a variety of observational data sets have been used to attribute model biases, some uncertainties in the results remain, which highlights the need for more observations, particularly concurrent measurements of atmospheric and snow aerosols and the deposition fluxes of aerosols, in future campaigns.

  1. Column-integrated aerosol optical properties and direct radiative forcing over the urban-industrial megacity Nanjing in the Yangtze River Delta, China.

    Science.gov (United States)

    Kang, Na; Kumar, K Raghavendra; Yu, Xingna; Yin, Yan

    2016-09-01

    Aerosol optical properties were measured and analyzed through the ground-based remote sensing Aerosol Robotic Network (AERONET) over an urban-industrial site, Nanjing (32.21° N, 118.72° E, and 62 m above sea level), in the Yangtze River Delta, China, during September 2007-August 2008. The annual averaged values of aerosol optical depth (AOD500) and the Ångström exponent (AE440-870) were measured to be 0.94 ± 0.52 and 1.10 ± 0.21, respectively. The seasonal averaged values of AOD500 (AE440-870) were noticed to be high in summer (autumn) and low in autumn (spring). The characterization of aerosol types showed the dominance of mixed type followed by the biomass burning and urban-industrial type of aerosol at Nanjing. Subsequently, the curvature (a 2) obtained from the second-order polynomial fit and the second derivative of AE (α') were also analyzed to understand the dominant aerosol type. The single scattering albedo at 440 nm (SSA440) varied from 0.88 to 0.93 with relatively lower (higher) values during the summer (spring), suggesting an increase in black carbon and mineral dust (desert dust) aerosols of absorbing (scattering) nature. The averaged monthly and seasonal evolutions of shortwave (0.3-4.0 μm) direct aerosol radiative forcing (DARF) values were computed from the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model both at the top of atmosphere (TOA) and bottom of atmosphere (SUR) during the study period. Further, the aerosol forcing efficiency (AFE) and the corresponding atmospheric heating rates (AHR) were also estimated from the forcing within the atmosphere (ATM). The derived DARF values, therefore, produced a warming effect within the atmosphere due to strong absorption of solar radiation.

  2. A GCM Study of Responses of the Atmospheric Water Cycle of West Africa and the Atlantic to Saharan Dust Radiative Forcing

    Science.gov (United States)

    Lau, K. M.; Kim, K. M.; Sud, Y. C.; Walker, G. K.

    2009-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summerr, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are ehanIed over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer overr the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at0

  3. Regional and monthly and clear-sky aerosol direct radiative effect (and forcing derived from the GlobAEROSOL-AATSR satellite aerosol product

    Directory of Open Access Journals (Sweden)

    G. E. Thomas

    2013-01-01

    Full Text Available Using the GlobAEROSOL-AATSR dataset, estimates of the instantaneous, clear-sky, direct aerosol radiative effect and radiative forcing have been produced for the year 2006. Aerosol Robotic Network sun-photometer measurements have been used to characterise the random and systematic error in the GlobAEROSOL product for 22 regions covering the globe. Representative aerosol properties for each region were derived from the results of a wide range of literature sources and, along with the de-biased GlobAEROSOL AODs, were used to drive an offline version of the Met Office unified model radiation scheme. In addition to the mean AOD, best-estimate run of the radiation scheme, a range of additional calculations were done to propagate uncertainty estimates in the AOD, optical properties, surface albedo and errors due to the temporal and spatial averaging of the AOD fields. This analysis produced monthly, regional estimates of the clear-sky aerosol radiative effect and its uncertainty, which were combined to produce annual, global mean values of (−6.7 ± 3.9 W m−2 at the top of atmosphere (TOA and (−12 ± 6 W m−2 at the surface. These results were then used to give estimates of regional, clear-sky aerosol direct radiative forcing, using modelled pre-industrial AOD fields for the year 1750 calculated for the AEROCOM PRE experiment. However, as it was not possible to quantify the uncertainty in the pre-industrial aerosol loading, these figures can only be taken as indicative and their uncertainties as lower bounds on the likely errors. Although the uncertainty on aerosol radiative effect presented here is considerably larger than most previous estimates, the explicit inclusion of the major sources of error in the calculations suggest that they are closer to the true constraint on this figure from similar methodologies, and point to the need for more, improved estimates of both global aerosol loading and aerosol optical properties.

  4. Fundamentals of negative refractive index optical trapping: forces and radiation pressures exerted by focused Gaussian beams using the generalized Lorenz-Mie theory.

    Science.gov (United States)

    Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

    2010-11-04

    Based on the generalized Lorenz-Mie theory (GLMT), this paper reveals, for the first time in the literature, the principal characteristics of the optical forces and radiation pressure cross-sections exerted on homogeneous, linear, isotropic and spherical hypothetical negative refractive index (NRI) particles under the influence of focused Gaussian beams in the Mie regime. Starting with ray optics considerations, the analysis is then extended through calculating the Mie coefficients and the beam-shape coefficients for incident focused Gaussian beams. Results reveal new and interesting trapping properties which are not observed for commonly positive refractive index particles and, in this way, new potential applications in biomedical optics can be devised.

  5. Radiations

    International Nuclear Information System (INIS)

    Pujol Mora, J.

    1999-01-01

    The exposition to ionizing radiations is a constant fact in the life of the human being and its utilization as diagnostic and therapeutic method is generalized. However, it is notorious how as years go on, the fear to the ionizing radiation seems to persist too, and this fact is not limited to the common individual, but to the technical personnel and professional personnel that labors with them same. (S. Grainger) [es

  6. Radiation

    International Nuclear Information System (INIS)

    Davidson, J.H.

    1986-01-01

    The basic facts about radiation are explained, along with some simple and natural ways of combating its ill-effects, based on ancient healing wisdom as well as the latest biochemical and technological research. Details are also given of the diet that saved thousands of lives in Nagasaki after the Atomic bomb attack. Special comment is made on the use of radiation for food processing. (U.K.)

  7. Simulating Black Carbon and Dust and their Radiative Forcing in Seasonal Snow: A Case Study over North China with Field Campaign Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chun; Hu, Zhiyuan; Qian, Yun; Leung, Lai-Yung R.; Huang, J.; Huang, Maoyi; Jin, Jiming; Flanner, M. G.; Zhang, Rudong; Wang, Hailong; Yan, Huiping; Lu, Zifeng; Streets, D. G.

    2014-10-30

    A state-of-the-art regional model, WRF-Chem, is coupled with the SNICAR model that includes the sophisticated representation of snow metamorphism processes available for climate study. The coupled model is used to simulate the black carbon (BC) and dust concentrations and their radiative forcing in seasonal snow over North China in January-February of 2010, with extensive field measurements used to evaluate the model performance. In general, the model simulated spatial variability of BC and dust mass concentrations in the top snow layer (hereafter BCS and DSTS, respectively) are quantitatively or qualitatively consistent with observations. The model generally moderately underestimates BCS in the clean regions but significantly overestimates BCS in some polluted regions. Most model results fall into the uncertainty ranges of observations. The simulated BCS and DSTS are highest with >5000 ng g-1 and up to 5 mg g-1, respectively, over the source regions and reduce to <50 ng g-1 and <1 μg g-1, respectively, in the remote regions. BCS and DSTS introduce similar magnitude of radiative warming (~10 W m-2) in snowpack, which is comparable to the magnitude of surface radiative cooling due to BC and dust in the atmosphere. This study represents the first effort in using a regional modeling framework to simulate BC and dust and their direct radiative forcing in snow. Although a variety of observational datasets have been used to attribute model biases, some uncertainties in the results remain, which highlights the need for more observations, particularly concurrent measurements of atmospheric and snow aerosols and the deposition fluxes of aerosols, in future campaigns.

  8. The Development of Radiation hardened tele-robot system - Development of artificial force reflection control for teleoperated mobile robots

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ju Jang; Hong, Sun Gi; Kang, Young Hoon; Kim, Min Soeng [Korea Advanced Institute of Science and Technology, Taejon (Korea)

    1999-04-01

    One of the most important issues in teleoperation is to provide the sense of telepresence so as to conduct the task more reliably. In particular, teleoperated mobile robots are needed to have some kinds of backup system when the operator is blind for remote situation owing to the failure of vision system. In the first year, the idea of artificial force reflection was researched to enhance the reliability of operation when the mobile robot travels on the plain ground. In the second year, we extend previous results to help the teleoperator even when the robot climbs stairs. Finally, we apply the developed control algorithms to real experiments. The artificial force reflection method has two modes; traveling on the plain ground and climbing stairs. When traveling on the plain ground, the force information is artificially generated by using the range data from the environment while generating the impulse force when climbing stairs. To verify the validity of our algorithm, we develop the simulator which consists of the joystick and the visual display system. Through some experiments using this system, we confirm the validity and effectiveness of our new idea of artificial force reflection in the teleoperated mobile robot. 11 refs., 30 figs. (Author)

  9. Radiation

    International Nuclear Information System (INIS)

    Winther, J.F.; Ulbak, K.; Dreyer, L.; Pukkala, E.; Oesterlind, A.

    1997-01-01

    Exposure to solar and ionizing radiation increases the risk for cancer in humans. Some 5% of solar radiation is within the ultraviolet spectrum and may cause both malignant melanoma and non-melanocytic skin cancer; the latter is regarded as a benign disease and is accordingly not included in our estimation of avoidable cancers. Under the assumption that the rate of occurrence of malignant melanoma of the buttocks of both men and women and of the scalp of women would apply to all parts of the body in people completely unexposed to solar radiation, it was estimated that approximately 95% of all malignant melanomas arising in the Nordic populations around the year 2000 will be due to exposure to natural ultraviolet radiation, equivalent to an annual number of about 4700 cas