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Sample records for size distribution analysis

  1. Remnant lipoprotein size distribution profiling via dynamic light scattering analysis.

    PubMed

    Chandra, Richa; Mellis, Birgit; Garza, Kyana; Hameed, Samee A; Jurica, James M; Hernandez, Ana V; Nguyen, Mia N; Mittal, Chandra K

    2016-11-01

    Remnant lipoproteins (RLP) are a metabolically derived subpopulation of triglyceride-rich lipoproteins (TRL) in human blood that are involved in the metabolism of dietary fats or triglycerides. RLP, the smaller and denser variants of TRL particles, are strongly correlated with cardiovascular disease (CVD) and were listed as an emerging atherogenic risk factor by the AHA in 2001. Varying analytical techniques used in clinical studies in the size determination of RLP contribute to conflicting hypotheses in regard to whether larger or smaller RLP particles contribute to CVD progression, though multiple pathways may exist. We demonstrated a unique combinatorial bioanalytical approach involving the preparative immunoseparation of RLP, and dynamic light scattering for size distribution analysis. This is a new facile and robust methodology for the size distribution analysis of RLP that in conjunction with clinical studies may reveal the mechanisms by which RLP cause CVD progression. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Growing axons analysis by using Granulometric Size Distribution

    NASA Astrophysics Data System (ADS)

    Gonzalez, Mariela A.; Ballarin, Virginia L.; Rapacioli, Melina; Celín, A. R.; Sánchez, V.; Flores, V.

    2011-09-01

    Neurite growth (neuritogenesis) in vitro is a common methodology in the field of developmental neurobiology. Morphological analyses of growing neurites are usually difficult because their thinness and low contrast usually prevent to observe clearly their shape, number, length and spatial orientation. This paper presents the use of the granulometric size distribution in order to automatically obtain information about the shape, size and spatial orientation of growing axons in tissue cultures. The results here presented show that the granulometric size distribution results in a very useful morphological tool since it allows the automatic detection of growing axons and the precise characterization of a relevant parameter indicative of the axonal growth spatial orientation such as the quantification of the angle of deviation of the growing direction. The developed algorithms automatically quantify this orientation by facilitating the analysis of these images, which is important given the large number of images that need to be processed for this type of study.

  3. Characterization of Flocs and Floc Size Distributions Using Image Analysis.

    PubMed

    Sun, Siwei; Weber-Shirk, Monroe; Lion, Leonard W

    2016-01-01

    A nonintrusive digital imaging process was developed to study particle size distributions created through flocculation and sedimentation. Quantification of particle size distributions under different operating conditions can be of use in the understanding of aggregation mechanisms. This process was calibrated by measuring standardized polystyrene particles of known size and was utilized to count and measure individual kaolin clay particles as well as aggregates formed by coagulation with polyaluminum chloride and flocculation. Identification of out-of-focus flocs was automated with LabVIEW and used to remove them from the database that was analyzed. The particle diameter of the test suspension of kaolinite clay was measured to be 7.7 ± 3.8 μm and a linear relationship was obtained between turbidity and the concentration of clay particles determined by imaging. The analysis technique was applied to characterize flocs and floc particle size distribution as a function of coagulant dose. Removal of flocs by sedimentation was characterized by imaging, and the negative logarithm of the fraction of turbidity remaining after settling had a linear relationship with the logarithm of aluminum dose. The maximum floc size observed in the settled water was less than 120 μm, which was in accordance with the value predicted by a model for the capture velocity of the experimental tube settler of 0.21 mm/s.

  4. Characterization of Flocs and Floc Size Distributions Using Image Analysis

    PubMed Central

    Sun, Siwei; Weber-Shirk, Monroe; Lion, Leonard W.

    2016-01-01

    Abstract A nonintrusive digital imaging process was developed to study particle size distributions created through flocculation and sedimentation. Quantification of particle size distributions under different operating conditions can be of use in the understanding of aggregation mechanisms. This process was calibrated by measuring standardized polystyrene particles of known size and was utilized to count and measure individual kaolin clay particles as well as aggregates formed by coagulation with polyaluminum chloride and flocculation. Identification of out-of-focus flocs was automated with LabVIEW and used to remove them from the database that was analyzed. The particle diameter of the test suspension of kaolinite clay was measured to be 7.7 ± 3.8 μm and a linear relationship was obtained between turbidity and the concentration of clay particles determined by imaging. The analysis technique was applied to characterize flocs and floc particle size distribution as a function of coagulant dose. Removal of flocs by sedimentation was characterized by imaging, and the negative logarithm of the fraction of turbidity remaining after settling had a linear relationship with the logarithm of aluminum dose. The maximum floc size observed in the settled water was less than 120 μm, which was in accordance with the value predicted by a model for the capture velocity of the experimental tube settler of 0.21 mm/s. PMID:26909006

  5. Analysis of scale-invariant slab avalanche size distributions

    NASA Astrophysics Data System (ADS)

    Faillettaz, J.; Louchet, F.; Grasso, J.-R.; Daudon, D.

    2003-04-01

    Scale invariance of snow avalanche sizes was reported for the first time in 2001 by Louchet et al. at the EGS conference, using both acoustic emission duration, and the surface of the crown step left at the top of the starting zone, where the former parameter characterises the size of the total avalanche flow, and the latter that of the starting zone. The present paper focuses on parameters of the second type, that are more directly related to precise release mechanisms, vz. the crown crack length L, the crown crack or slab depth H, the crown step surface HxL, the volume HxL^2 of the snow involved in the starting zone, and LxH^2 which is a measure of the stress concentration at the basal crack tip at failure. The analysis is performed on two data sets, from la Grande Plagne (GP) and Tignes (T) ski resorts. For both catalogs, cumulative distributions of L, H, HxL, HxL^2 and LxH^2 are shown to be roughly linear in a log-log plot. i.e. consistent with so-called scale invariant (or power law) distributions for both triggered and natural avalanches. Plateaus are observed at small sizes, and roll-offs at large sizes. The power law exponents for each of these quantities are roughly independent of the ski resort (GP or T) they come from. In contrast, exponents for natural events are significantly smaller than those for artificial ones. We analyse the possible reasons for the scale invariance of these quantities, for the possible "universality" of the exponents corresponding to a given triggering mode, and for the difference in exponents between triggered and natural events. The physical meaning of the observed roll-offs and plateaus is also discussed. The power law distributions analysed here provide the occurrence probability of an avalanche of a given (starting) volume in a given time period on a given area. A possible use of this type of distributions for snow avalanche hazard assessment is contemplated, as it is for earthquakes or rockfalls.

  6. Rank-size distribution and primate city characteristics in India--a temporal analysis.

    PubMed

    Das, R J; Dutt, A K

    1993-02-01

    "This paper is an analysis of the historical change in city size distribution in India....Rank-size distribution at national level and primate city-size distribution at regional levels are examined....The paper also examines, in the Indian context, the relation between rank-size distribution and an integrated urban system, and the normative nature of the latter as a spatial organization of human society. Finally, we have made a modest attempt to locate the research on city-size distribution...." excerpt

  7. Modelling adipocytes size distribution.

    PubMed

    Soula, H A; Julienne, H; Soulage, C O; Géloën, A

    2013-09-07

    Adipocytes are cells whose task is to store excess energy as lipid droplets in their cytoplasm. Adipocytes can adapt their size according to the lipid amount to be stored. Adipocyte size variation can reach one order of magnitude inside the same organism which is unique among cells. A striking feature in adipocytes size distribution is the lack of characteristic size since typical size distributions are bimodal. Since energy can be stored and retrieved and adipocytes are responsible for these lipid fluxes, we propose a simple model of size-dependent lipid fluxes that is able to predict typical adipocytes size distribution. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. An analysis of the size distribution of Italian firms by age

    NASA Astrophysics Data System (ADS)

    Cirillo, Pasquale

    2010-02-01

    In this paper we analyze the size distribution of Italian firms by age. In other words, we want to establish whether the way that the size of firms is distributed varies as firms become old. As a proxy of size we use capital. In [L.M.B. Cabral, J. Mata, On the evolution of the firm size distribution: Facts and theory, American Economic Review 93 (2003) 1075-1090], the authors study the distribution of Portuguese firms and they find out that, while the size distribution of all firms is fairly stable over time, the distributions of firms by age groups are appreciably different. In particular, as the age of the firms increases, their size distribution on the log scale shifts to the right, the left tails becomes thinner and the right tail thicker, with a clear decrease of the skewness. In this paper, we perform a similar analysis with Italian firms using the CEBI database, also considering firms’ growth rates. Although there are several papers dealing with Italian firms and their size distribution, to our knowledge a similar study concerning size and age has not been performed yet for Italy, especially with such a big panel.

  9. Nanomaterial size distribution analysis via liquid nebulization coupled with ion mobility spectrometry (LN-IMS).

    PubMed

    Jeon, Seongho; Oberreit, Derek R; Van Schooneveld, Gary; Hogan, Christopher J

    2016-02-21

    We apply liquid nebulization (LN) in series with ion mobility spectrometry (IMS, using a differential mobility analyzer coupled to a condensation particle counter) to measure the size distribution functions (the number concentration per unit log diameter) of gold nanospheres in the 5-30 nm range, 70 nm × 11.7 nm gold nanorods, and albumin proteins originally in aqueous suspensions. In prior studies, IMS measurements have only been carried out for colloidal nanoparticles in this size range using electrosprays for aerosolization, as traditional nebulizers produce supermicrometer droplets which leave residue particles from non-volatile species. Residue particles mask the size distribution of the particles of interest. Uniquely, the LN employed in this study uses both online dilution (with dilution factors of up to 10(4)) with ultra-high purity water and a ball-impactor to remove droplets larger than 500 nm in diameter. This combination enables hydrosol-to-aerosol conversion preserving the size and morphology of particles, and also enables higher non-volatile residue tolerance than electrospray based aerosolization. Through LN-IMS measurements we show that the size distribution functions of narrowly distributed but similarly sized particles can be distinguished from one another, which is not possible with Nanoparticle Tracking Analysis in the sub-30 nm size range. Through comparison to electron microscopy measurements, we find that the size distribution functions inferred via LN-IMS measurements correspond to the particle sizes coated by surfactants, i.e. as they persist in colloidal suspensions. Finally, we show that the gas phase particle concentrations inferred from IMS size distribution functions are functions of only of the liquid phase particle concentration, and are independent of particle size, shape, and chemical composition. Therefore LN-IMS enables characterization of the size, yield, and polydispersity of sub-30 nm particles.

  10. Comparison of photon correlation spectroscopy with photosedimentation analysis for the determination of aqueous colloid size distributions

    USGS Publications Warehouse

    Rees, T.F.

    1990-01-01

    Photon correlation spectroscopy (PCS) utilizes the Doppler frequency shift of photons scattered off particles undergoing Brownian motion to determine the size of colloids suspended in water. Photosedimentation analysis (PSA) measures the time-dependent change in optical density of a suspension of colloidal particles undergoing centrifugation. A description of both techniques, important underlying assumptions, and limitations are given. Results for a series of river water samples show that the colloid-size distribution means are statistically identical as determined by both techniques. This also is true of the mass median diameter (MMD), even though MMD values determined by PSA are consistently smaller than those determined by PCS. Because of this small negative bias, the skew parameters for the distributions are generally smaller for the PCS-determined distributions than for the PSA-determined distributions. Smaller polydispersity indices for the distributions are also determined by PCS. -from Author

  11. Measurement of bubble and pellet size distributions: past and current image analysis technology.

    PubMed

    Junker, Beth

    2006-08-01

    Measurements of bubble and pellet size distributions are useful for biochemical process optimizations. The accuracy, representation, and simplicity of these measurements improve when the measurement is performed on-line and in situ rather than off-line using a sample. Historical and currently available measurement systems for photographic methods are summarized for bubble and pellet (morphology) measurement applications. Applications to cells, mycelia, and pellets measurements have driven key technological developments that have been applied for bubble measurements. Measurement trade-offs exist to maximize accuracy, extend range, and attain reasonable cycle times. Mathematical characterization of distributions using standard statistical techniques is straightforward, facilitating data presentation and analysis. For the specific application of bubble size distributions, selected bioreactor operating parameters and physicochemical conditions alter distributions. Empirical relationships have been established in some cases where sufficient data have been collected. In addition, parameters and conditions with substantial effects on bubble size distributions were identified and their relative effects quantified. This information was used to guide required accuracy and precision targets for bubble size distribution measurements from newly developed novel on-line and in situ bubble measurement devices.

  12. Hail Size Distribution Mapping

    NASA Technical Reports Server (NTRS)

    2008-01-01

    A 3-D weather radar visualization software program was developed and implemented as part of an experimental Launch Pad 39 Hail Monitor System. 3DRadPlot, a radar plotting program, is one of several software modules that form building blocks of the hail data processing and analysis system (the complete software processing system under development). The spatial and temporal mapping algorithms were originally developed through research at the University of Central Florida, funded by NASA s Tropical Rainfall Measurement Mission (TRMM), where the goal was to merge National Weather Service (NWS) Next-Generation Weather Radar (NEXRAD) volume reflectivity data with drop size distribution data acquired from a cluster of raindrop disdrometers. In this current work, we adapted these algorithms to process data from a cluster of hail disdrometers positioned around Launch Pads 39A or 39B, along with the corresponding NWS radar data. Radar data from all NWS NEXRAD sites is archived at the National Climatic Data Center (NCDC). That data can be readily accessed at . 3DRadPlot plots Level III reflectivity data at four scan elevations (this software is available at Open Channel Software, ). By using spatial and temporal interpolation/extrapolation based on hydrometeor fall dynamics, we can merge the hail disdrometer array data coupled with local Weather Surveillance Radar-1988, Doppler (WSR-88D) radial velocity and reflectivity data into a 4-D (3-D space and time) picture of hail size distributions. Hail flux maps can then be generated and used for damage prediction and assessment over specific surfaces corresponding to structures within the disdrometer array volume. Immediately following a hail storm, specific damage areas and degree of damage can be identified for inspection crews.

  13. A comparative study of submicron particle sizing platforms: accuracy, precision and resolution analysis of polydisperse particle size distributions.

    PubMed

    Anderson, Will; Kozak, Darby; Coleman, Victoria A; Jämting, Åsa K; Trau, Matt

    2013-09-01

    The particle size distribution (PSD) of a polydisperse or multimodal system can often be difficult to obtain due to the inherent limitations in established measurement techniques. For this reason, the resolution, accuracy and precision of three new and one established, commercially available and fundamentally different particle size analysis platforms were compared by measuring both individual and a mixed sample of monodisperse, sub-micron (220, 330, and 410 nm - nominal modal size) polystyrene particles. The platforms compared were the qNano Tunable Resistive Pulse Sensor, Nanosight LM10 Particle Tracking Analysis System, the CPS Instruments's UHR24000 Disc Centrifuge, and the routinely used Malvern Zetasizer Nano ZS Dynamic Light Scattering system. All measurements were subjected to a peak detection algorithm so that the detected particle populations could be compared to 'reference' Transmission Electron Microscope measurements of the individual particle samples. Only the Tunable Resistive Pulse Sensor and Disc Centrifuge platforms provided the resolution required to resolve all three particle populations present in the mixed 'multimodal' particle sample. In contrast, the light scattering based Particle Tracking Analysis and Dynamic Light Scattering platforms were only able to detect a single population of particles corresponding to either the largest (410 nm) or smallest (220 nm) particles in the multimodal sample, respectively. When the particle sets were measured separately (monomodal) each platform was able to resolve and accurately obtain a mean particle size within 10% of the Transmission Electron Microscope reference values. However, the broadness of the PSD measured in the monomodal samples deviated greatly, with coefficients of variation being ~2-6-fold larger than the TEM measurements across all four platforms. The large variation in the PSDs obtained from these four, fundamentally different platforms, indicates that great care must still be taken in

  14. A statistical analysis of North East Atlantic (submicron) aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Dall'Osto, M.; Monahan, C.; Greaney, R.; Beddows, D. C. S.; Harrison, R. M.; Ceburnis, D.; O'Dowd, C. D.

    2011-12-01

    The Global Atmospheric Watch research station at Mace Head (Ireland) offers the possibility to sample some of the cleanest air masses being imported into Europe as well as some of the most polluted being exported out of Europe. We present a statistical cluster analysis of the physical characteristics of aerosol size distributions in air ranging from the cleanest to the most polluted for the year 2008. Data coverage achieved was 75% throughout the year. By applying the Hartigan-Wong k-Means method, 12 clusters were identified as systematically occurring. These 12 clusters could be further combined into 4 categories with similar characteristics, namely: coastal nucleation category (occurring 21.3 % of the time), open ocean nucleation category (occurring 32.6% of the time), background clean marine category (occurring 26.1% of the time) and anthropogenic category (occurring 20% of the time) aerosol size distributions. The coastal nucleation category is characterised by a clear and dominant nucleation mode at sizes less than 10 nm while the open ocean nucleation category is characterised by a dominant Aitken mode between 15 nm and 50 nm. The background clean marine aerosol exhibited a clear bimodality in the sub-micron size distribution, with although it should be noted that either the Aitken mode or the accumulation mode may dominate the number concentration. However, peculiar background clean marine size distributions with coarser accumulation modes are also observed during winter months. By contrast, the continentally-influenced size distributions are generally more monomodal (accumulation), albeit with traces of bimodality. The open ocean category occurs more often during May, June and July, corresponding with the North East (NE) Atlantic high biological period. Combined with the relatively high percentage frequency of occurrence (32.6%), this suggests that the marine biota is an important source of new nano aerosol particles in NE Atlantic Air.

  15. Structure analysis and size distribution of particulate matter from candles and kerosene combustion in burning chamber

    NASA Astrophysics Data System (ADS)

    Baitimirova, M.; Osite, A.; Katkevics, J.; Viksna, A.

    2012-08-01

    Burning of candles generates particulate matter of fine dimensions that produces poor indoor air quality, so it may cause harmful impact on human health. In this study solid aerosol particles of burning of candles of different composition and kerosene combustion were collected in a closed laboratory system. Present work describes particulate matter collection for structure analysis and the relationship between source and size distribution of particulate matter. The formation mechanism of particulate matter and their tendency to agglomerate also are described. Particles obtained from kerosene combustion have normal size distribution. Whereas, particles generated from the burning of stearin candles have distribution shifted towards finer particle size range. If an additive of stearin to paraffin candle is used, particle size distribution is also observed in range of towards finer particles. A tendency to form agglomerates in a short time is observed in case of particles obtained from kerosene combustion, while in case of particles obtained from burning of candles of different composition such a tendency is not observed. Particles from candles and kerosene combustion are Aitken and accumulation mode particles

  16. Measurements of droplet size distribution and analysis of nasal spray atomization from different actuation pressure.

    PubMed

    Inthavong, Kiao; Fung, Man Chiu; Yang, William; Tu, Jiyuan

    2015-02-01

    To evaluate the deposition efficiency of spray droplets in a nasal cavity produced from a spray device, it is important to determine droplet size distribution, velocity, and its dispersion during atomization. Due to the limiting geometric dimensions of the nasal cavity airway, the spray plume cannot develop to its full size inside the nasal vestibule to penetrate the nasal valve region for effective drug deposition. Particle/droplet image analysis was used to determine local mean droplet sizes at eight regions within the spray plume under different actuation pressures that represent typical hand operation from pediatric to adult patients. The results showed that higher actuation pressure produces smaller droplets in the atomization. Stronger actuation pressure typical of adult users produces a longer period of the fully atomized spray stage, despite a shorter overall spray duration. This produces finer droplets when compared with the data obtained by weaker actuation pressure, typical of pediatric users. The experimental technique presented is able to capture a more complete representation of the droplet size distribution and the atomization process during an actuation. The measured droplet size distribution produced can be related to the empirically defined deposition efficiency curve of the nasal cavity, allowing a prediction of the likely deposition.

  17. Business size distributions

    NASA Astrophysics Data System (ADS)

    D'Hulst, R.; Rodgers, G. J.

    2001-10-01

    In a recent work, we introduced two models for the dynamics of customers trying to find the business that best corresponds to their expectation for the price of a commodity. In agreement with the empirical data, a power-law distribution for the business sizes was obtained, taking the number of customers of a business as a proxy for its size. Here, we extend one of our previous models in two different ways. First, we introduce a business aggregation rate that is fitness dependent, which allows us to reproduce a spread in empirical data from one country to another. Second, we allow the bankruptcy rate to take a different functional form, to be able to obtain a log-normal distribution with power-law tails for the size of the businesses.

  18. Sampling surface particle size distributions and stability analysis of deep channel in the Pearl River Estuary

    NASA Astrophysics Data System (ADS)

    Feng, Hao-chuan; Zhang, Wei; Zhu, Yu-liang; Lei, Zhi-yi; Ji, Xiao-mei

    2017-06-01

    Particle size distributions (PSDs) of bottom sediments in a coastal zone are generally multimodal due to the complexity of the dynamic environment. In this paper, bottom sediments along the deep channel of the Pearl River Estuary (PRE) are used to understand the multimodal PSDs' characteristics and the corresponding depositional environment. The results of curve-fitting analysis indicate that the near-bottom sediments in the deep channel generally have a bimodal distribution with a fine component and a relatively coarse component. The particle size distribution of bimodal sediment samples can be expressed as the sum of two lognormal functions and the parameters for each component can be determined. At each station of the PRE, the fine component makes up less volume of the sediments and is relatively poorly sorted. The relatively coarse component, which is the major component of the sediments, is even more poorly sorted. The interrelations between the dynamics and particle size of the bottom sediment in the deep channel of the PRE have also been investigated by the field measurement and simulated data. The critical shear velocity and the shear velocity are calculated to study the stability of the deep channel. The results indicate that the critical shear velocity has a similar distribution over large part of the deep channel due to the similar particle size distribution of sediments. Based on a comparison between the critical shear velocities derived from sedimentary parameters and the shear velocities obtained by tidal currents, it is likely that the depositional area is mainly distributed in the northern part of the channel, while the southern part of the deep channel has to face higher erosion risk.

  19. Advanced analysis of polymer emulsions: Particle size and particle size distribution by field-flow fractionation and dynamic light scattering.

    PubMed

    Makan, Ashwell C; Spallek, Markus J; du Toit, Madeleine; Klein, Thorsten; Pasch, Harald

    2016-04-15

    Field flow fractionation (FFF) is an advanced fractionation technique for the analyses of very sensitive particles. In this study, different FFF techniques were used for the fractionation and analysis of polymer emulsions/latexes. As model systems, a pure acrylic emulsion and emulsions containing titanium dioxide were prepared and analyzed. An acrylic emulsion polymerization was conducted, continuously sampled from the reactor and subsequently analyzed to determine the particle size, radius of gyration in specific, of the latex particles throughout the polymerization reaction. Asymmetrical flow field-flow fractionation (AF4) and sedimentation field-flow fractionation (SdFFF), coupled to a multidetector system, multi-angle laser light scattering (MALLS), ultraviolet (UV) and refractive index (RI), respectively, were used to investigate the evolution of particle sizes and particle size distributions (PSDs) as the polymerization progressed. The obtained particle sizes were compared against batch-mode dynamic light scattering (DLS). Results indicated differences between AF4 and DLS results due to DLS taking hydration layers into account, whereas both AF4 and SdFFF were coupled to MALLS detection, hence not taking the hydration layer into account for size determination. SdFFF has additional separation capabilities with a much higher resolution compared to AF4. The calculated radii values were 5 nm larger for SdFFF measurements for each analyzed sample against the corresponding AF4 values. Additionally a low particle size shoulder was observed for SdFFF indicating bimodality in the reactor very early during the polymerization reaction. Furthermore, different emulsions were mixed with inorganic species used as additives in cosmetics and coatings such as TiO2. These complex mixtures of species were analyzed to investigate the retention and particle interaction behavior under different AF4 experimental conditions, such as the mobile phase. The AF4 system was coupled online

  20. Size matters: point pattern analysis biases the estimation of spatial properties of stomata distribution.

    PubMed

    Naulin, Paulette I; Valenzuela, Gerardo; Estay, Sergio A

    2017-03-01

    Stomata distribution is an example of biological patterning. Formal methods used to study stomata patterning are generally based on point-pattern analysis, which assumes that stomata are points and ignores the constraints imposed by size on the placement of neighbors. The inclusion of size in the analysis requires the use of a null model based on finite-size object geometry. In this study, we compare the results obtained by analyzing samples from several species using point and disc null models. The results show that depending on the null model used, there was a 20% reduction in the number of samples classified as uniform; these results suggest that stomata patterning is not as general as currently reported. Some samples changed drastically from being classified as uniform to being classified as clustered. In samples of Arabidopsis thaliana, only the disc model identified clustering at high densities of stomata. This reinforces the importance of selecting an appropriate null model to avoid incorrect inferences about underlying biological mechanisms. Based on the results gathered here, we encourage researchers to abandon point-pattern analysis when studying stomata patterning; more realistic conclusions can be drawn from finite-size object analysis. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  1. Finite-size analysis of a continuous-variable quantum key distribution

    SciTech Connect

    Leverrier, Anthony; Grangier, Philippe

    2010-06-15

    The goal of this paper is to extend the framework of finite-size analysis recently developed for quantum key distribution to continuous-variable protocols. We do not solve this problem completely here, and we mainly consider the finite-size effects on the parameter estimation procedure. Despite the fact that some questions are left open, we are able to give an estimation of the secret key rate for protocols which do not contain a postselection procedure. As expected, these results are significantly more pessimistic than those obtained in the asymptotic regime. However, we show that recent continuous-variable protocols are able to provide fully secure secret keys in the finite-size scenario, over distances larger than 50 km.

  2. MetaZipf. A dynamic meta-analysis of city size distributions

    PubMed Central

    2017-01-01

    The results from urban scaling in recent years have held the promise of increased efficiency to the societies who could actively control the distribution of their cities’ size. However, little evidence exists as to the factors which influence the level of urban unevenness, as expressed by the slope of the rank-size distribution, partly because the diversity of results found in the literature follows the heterogeneity of analysis specifications. In this study, I set up a meta-analysis of Zipf’s law which accounts for technical as well as topical factors of variations of Zipf’s coefficient. I found 86 studies publishing at least one empirical estimation of this coefficient and recorded their metadata into an open database. I regressed the 1962 corresponding estimates with variables describing the study and the estimation process as well as socio-demographic variables describing the territory under enquiry. A dynamic meta-analysis was also performed to look for factors of evolution of city size unevenness. The results of the most interesting models are presented in the article, whereas all analyses can be reproduced on a dedicated online platform. The results show that on average, 40% of the variation of Zipf’s coefficients is due to the technical choices. The main other variables associated with distinct evolutions are linked to the urbanisation process rather than the process of economic development and population growth. Finally, no evidence was found to support the effectiveness of past planning actions in modifying this urban feature. PMID:28850594

  3. MetaZipf. A dynamic meta-analysis of city size distributions.

    PubMed

    Cottineau, Clémentine

    2017-01-01

    The results from urban scaling in recent years have held the promise of increased efficiency to the societies who could actively control the distribution of their cities' size. However, little evidence exists as to the factors which influence the level of urban unevenness, as expressed by the slope of the rank-size distribution, partly because the diversity of results found in the literature follows the heterogeneity of analysis specifications. In this study, I set up a meta-analysis of Zipf's law which accounts for technical as well as topical factors of variations of Zipf's coefficient. I found 86 studies publishing at least one empirical estimation of this coefficient and recorded their metadata into an open database. I regressed the 1962 corresponding estimates with variables describing the study and the estimation process as well as socio-demographic variables describing the territory under enquiry. A dynamic meta-analysis was also performed to look for factors of evolution of city size unevenness. The results of the most interesting models are presented in the article, whereas all analyses can be reproduced on a dedicated online platform. The results show that on average, 40% of the variation of Zipf's coefficients is due to the technical choices. The main other variables associated with distinct evolutions are linked to the urbanisation process rather than the process of economic development and population growth. Finally, no evidence was found to support the effectiveness of past planning actions in modifying this urban feature.

  4. Sample size calculation for differential expression analysis of RNA-seq data under Poisson distribution

    PubMed Central

    Li, Chung-I; Su, Pei-Fang; Guo, Yan

    2013-01-01

    Sample size determination is an important issue in the experimental design of biomedical research. Because of the complexity of RNA-seq experiments, however, the field currently lacks a sample size method widely applicable to differential expression studies utilizing RNA-seq technology. In this report, we propose several methods for sample size calculation for single-gene differential expression analysis of RNA-seq data under Poisson distribution. These methods are then extended to multiple genes, with consideration for addressing the multiple testing problem by controlling false discovery rate. Moreover, most of the proposed methods allow for closedform sample size formulas with specification of the desired minimum fold change and minimum average read count, and thus are not computationally intensive. Simulation studies to evaluate the performance of the proposed sample size formulas are presented; the results indicate that our methods work well, with achievement of desired power. Finally, our sample size calculation methods are applied to three real RNA-seq data sets. PMID:24088268

  5. Sample size calculation for differential expression analysis of RNA-seq data under Poisson distribution.

    PubMed

    Li, Chung-I; Su, Pei-Fang; Guo, Yan; Shyr, Yu

    2013-01-01

    Sample size determination is an important issue in the experimental design of biomedical research. Because of the complexity of RNA-seq experiments, however, the field currently lacks a sample size method widely applicable to differential expression studies utilising RNA-seq technology. In this report, we propose several methods for sample size calculation for single-gene differential expression analysis of RNA-seq data under Poisson distribution. These methods are then extended to multiple genes, with consideration for addressing the multiple testing problem by controlling false discovery rate. Moreover, most of the proposed methods allow for closed-form sample size formulas with specification of the desired minimum fold change and minimum average read count, and thus are not computationally intensive. Simulation studies to evaluate the performance of the proposed sample size formulas are presented; the results indicate that our methods work well, with achievement of desired power. Finally, our sample size calculation methods are applied to three real RNA-seq data sets.

  6. Latitudinal variation in the shape of the species body size distribution: an analysis using freshwater fishes.

    PubMed

    Knouft, Jason H

    2004-05-01

    Many taxonomic and ecological assemblages of species exhibit a right-skewed body size-frequency distribution when characterized at a regional scale. Although this distribution has been frequently described, factors influencing geographic variation in the distribution are not well understood, nor are mechanisms responsible for distribution shape. In this study, variation in the species body size-frequency distributions of 344 regional communities of North American freshwater fishes is examined in relation to latitude, species richness, and taxonomic composition. Although the distribution of all species of North American fishes is right-skewed, a negative correlation exists between latitude and regional community size distribution skewness, with size distributions becoming left-skewed at high latitudes. This relationship is not an artifact of the confounding relationship between latitude and species richness in North American fishes. The negative correlation between latitude and regional community size distribution skewness is partially due to the geographic distribution of families of fishes and apparently enhanced by a nonrandom geographic distribution of species within families. These results are discussed in the context of previous explanations of factors responsible for the generation of species size-frequency distributions related to the fractal nature of the environment, energetics, and evolutionary patterns of body size in North American fishes.

  7. Digital Image Analysis Algorithm For Determination of Particle Size Distributions In Diesel Engines

    NASA Astrophysics Data System (ADS)

    Armas, O.; Ballesteros, R.; Gomez, A.

    One of the most serious problems associated to Diesel engines is pollutant emissions, standing out nitrogen oxides and particulate matter. However, although current emis- sions standards in Europe and America with regard to light vehicles and heavy duty engines refer the particulate limit in mass units, concern for knowing size and number of particles emitted by engines is being increased recently. This interest is promoted by last studies about particle harmful effects on health and is enhanced by recent changes in internal combustion engines technology. This study is focused on the implementation of a method to determine the particle size distribution made up in current methodology for vehicles certification in Europe. It will use an automated Digital Image Analysis Algorithm (DIAA) to determine particle size trends from Scanning Electron Microscope (SEM) images of filters charged in a dilution system used for measuring specific particulate emissions. The experimental work was performed on a steady state direct injection Diesel en- gine with 0.5 MW rated power, being considered as a typical engine in middle power industries. Particulate size distributions obtained using DIAA and a Scanning Mobil- ity Particle Sizer (SMPS), nowadays considered as the most reliable technique, were compared. Although number concentration detected by this method does not repre- sent real flowing particle concentration, this algorithm fairly reproduces the trends observed with SMPS when the engine load is varied.

  8. Analysis of Nuclear Mitochondrial DNA Segments of Nine Plant Species: Size, Distribution, and Insertion Loci

    PubMed Central

    Ko, Young-Joon

    2016-01-01

    Nuclear mitochondrial DNA segment (Numt) insertion describes a well-known phenomenon of mitochondrial DNA transfer into a eukaryotic nuclear genome. However, it has not been well understood, especially in plants. Numt insertion patterns vary from species to species in different kingdoms. In this study, the patterns were surveyed in nine plant species, and we found some tip-offs. First, when the mitochondrial genome size is relatively large, the portion of the longer Numt is also larger than the short one. Second, the whole genome duplication event increases the ratio of the shorter Numt portion in the size distribution. Third, Numt insertions are enriched in exon regions. This analysis may be helpful for understanding plant evolution. PMID:27729838

  9. Quantitative analysis of virus-like particle size and distribution by field-flow fractionation.

    PubMed

    Chuan, Yap P; Fan, Yuan Y; Lua, Linda; Middelberg, Anton P J

    2008-04-15

    Asymmetric flow field-flow fractionation (AFFFF) coupled with multiple-angle light scattering (MALS) is a powerful technique showing potential for the analysis of pharmaceutically-relevant virus-like particles (VLPs). A lack of published methods, and concerns that membrane adsorption during sample fractionation may cause sample aggregation, have limited widespread acceptance. Here we report a reliable optimized method for VLP analysis using AFFFF-MALS, and benchmark it against dynamic light scattering (DLS) and transmission electron microscopy (TEM). By comparing chemically identical VLPs having very different quaternary structure, sourced from both bacteria and insect cells, we show that optimized AFFFF analysis does not cause significant aggregation, and that accurate size and distribution information can be obtained for heterogeneous samples in a way not possible with TEM and DLS. Optimized AFFFF thus provides a quantitative way to monitor batch consistency for new vaccine products, and rapidly provides unique information on the whole population of particles within a sample.

  10. Real-Time Measurement of Electronic Cigarette Aerosol Size Distribution and Metals Content Analysis

    PubMed Central

    Brinkman, Marielle C.; Granville, Courtney A.; Gordon, Sydney M.; Clark, Pamela I.

    2016-01-01

    Introduction: Electronic cigarette (e-cigarette) use is increasing worldwide and is highest among both daily and nondaily smokers. E-cigarettes are perceived as a healthier alternative to combustible tobacco products, but their health risk factors have not yet been established, and one of them is lack of data on aerosol size generated by e-cigarettes. Methods: We applied a real-time, high-resolution aerosol differential mobility spectrometer to monitor the evolution of aerosol size and concentration during puff development. Particles generated by e-cigarettes were immediately delivered for analysis with minimal dilution and therefore with minimal sample distortion, which is critically important given the highly dynamic aerosol/vapor mixture inherent to e-cigarette emissions. Results: E-cigarette aerosols normally exhibit a bimodal particle size distribution: nanoparticles (11–25nm count median diameter) and submicron particles (96–175nm count median diameter). Each mode has comparable number concentrations (107–108 particles/cm3). “Dry puff” tests conducted with no e-cigarette liquid (e-liquid) present in the e-cigarette tank demonstrated that under these conditions only nanoparticles were generated. Analysis of the bulk aerosol collected on the filter showed that e-cigarette emissions contained a variety of metals. Conclusions: E-cigarette aerosol size distribution is different from that of combustible tobacco smoke. E-cigarettes generate high concentrations of nanoparticles and their chemical content requires further investigation. Despite the small mass of nanoparticles, their toxicological impact could be significant. Toxic chemicals that are attached to the small nanoparticles may have greater adverse health effects than when attached to larger submicron particles. Implications: The e-cigarette aerosol size distribution is different from that of combustible tobacco smoke and typically exhibits a bimodal behavior with comparable number concentrations

  11. Pore size distribution analysis of activated carbons prepared from coconut shell using methane adsorption data

    NASA Astrophysics Data System (ADS)

    Ahmadpour, A.; Okhovat, A.; Darabi Mahboub, M. J.

    2013-06-01

    The application of Stoeckli theory to determine pore size distribution (PSD) of activated carbons using high pressure methane adsorption data is explored. Coconut shell was used as a raw material for the preparation of 16 different activated carbon samples. Four samples with higher methane adsorption were selected and nitrogen adsorption on these adsorbents was also investigated. Some differences are found between the PSD obtained from the analysis of nitrogen adsorption isotherms and their PSD resulting from the same analysis using methane adsorption data. It is suggested that these differences may arise from the specific interactions between nitrogen molecules and activated carbon surfaces; therefore caution is required in the interpretation of PSD obtained from the nitrogen isotherm data.

  12. Particle size distribution of brown and white rice during gastric digestion measured by image analysis.

    PubMed

    Bornhorst, Gail M; Kostlan, Kevin; Singh, R Paul

    2013-09-01

    The particle size distribution of foods during gastric digestion indicates the amount of physical breakdown that occurred due to the peristaltic movement of the stomach walls in addition to the breakdown that initially occurred during oral processing. The objective of this study was to present an image analysis technique that was rapid, simple, and could distinguish between food components (that is, rice kernel and bran layer in brown rice). The technique was used to quantify particle breakdown of brown and white rice during gastric digestion in growing pigs (used as a model for an adult human) over 480 min of digestion. The particle area distributions were fit to a Rosin-Rammler distribution function. Brown and white rice exhibited considerable breakdown as the number of particles per image decreased over time. The median particle area (x(50)) increased during digestion, suggesting a gastric sieving phenomenon, where small particles were emptied and larger particles were retained for additional breakdown. Brown rice breakdown was further quantified by an examination of the bran layer fragments and rice grain pieces. The percentage of total particle area composed of bran layer fragments was greater in the distal stomach than the proximal stomach in the first 120 min of digestion. The results of this study showed that image analysis may be used to quantify particle breakdown of a soft food product during gastric digestion, discriminate between different food components, and help to clarify the role of food structure and processing in food breakdown during gastric digestion.

  13. SANDY: A Matlab tool to estimate the sediment size distribution from a sieve analysis

    NASA Astrophysics Data System (ADS)

    Ruiz-Martínez, Gabriel; Rivillas-Ospina, Germán Daniel; Mariño-Tapia, Ismael; Posada-Vanegas, Gregorio

    2016-07-01

    This paper presents a new computational tool called SANDY© which calculates the sediment size distribution and its textural parameters from a sieved sediment sample using Matlab®. The tool has been developed for professionals involved in the study of sediment transport along coastal margins, estuaries, rivers and desert dunes. The algorithm uses several types of statistical analyses to obtain the main textural characteristics of the sediment sample (D50, mean, sorting, skewness and kurtosis). SANDY© includes the method of moments (geometric, arithmetic and logarithmic approaches) and graphical methods (geometric, arithmetic and mixed approaches). In addition, it provides graphs of the sediment size distribution and its classification. The computational tool automatically exports all the graphs as enhanced metafile images and the final report is also exported as a plain text file. Parameters related to bed roughness such as Nikuradse and roughness length are also computed. Theoretical depositional environments are established by a discriminant function analysis. Using the uniformity coefficient the hydraulic conductivity of the sand as well as the porosity and void ratio of the sediment sample are obtained. The maximum relative density related to sand compaction is also computed. The Matlab® routine can compute one or several samples. SANDY© is a useful tool for estimating the sediment textural parameters which are the basis for studies of sediment transport.

  14. A theoretical analysis and prediction of pore size and pore size distribution in electrospun multilayer nanofibrous materials.

    PubMed

    Bagherzadeh, Roohollah; Najar, Saeed Shaikhzadeh; Latifi, Masoud; Tehran, Mohammad Amani; Kong, Lingxue

    2013-07-01

    Electrospinning process can fabricate nanomaterials with unique nanostructures for potential biomedical and environmental applications. However, the prediction and, consequently, the control of the porous structure of these materials has been impractical due to the complexity of the electrospinning process. In this research, a theoretical model for characterizing the porous structure of the electrospun nanofibrous network has been developed by combining the stochastic and stereological probability approaches. From consideration of number of fiber-to-fiber contacts in an electrospun nanofibrous assembly, geometrical and statistical theory relating morphological and structural parameters of the network to the characteristic dimensions of interfibers pores is provided. It has been shown that these properties are strongly influenced by the fiber diameter, porosity, and thickness of assembly. It is also demonstrated that at a given network porosity, increasing fiber diameter and thickness of the network reduces the characteristic dimensions of pores. It is also discussed that the role of fiber diameter and number of the layer in the assembly is dominant in controlling the pore size distribution of the networks. The theory has been validated experimentally and results compared with the existing theory to predict the pore size distribution of nanofiber mats. It is believed that the presented theory for estimation of pore size distribution is more realistic and useful for further studies of multilayer random nanofibrous assemblies. Copyright © 2013 Wiley Periodicals, Inc.

  15. Application of maximum entropy method for droplet size distribution prediction using instability analysis of liquid sheet

    NASA Astrophysics Data System (ADS)

    Movahednejad, E.; Ommi, F.; Hosseinalipour, S. M.; Chen, C. P.; Mahdavi, S. A.

    2011-12-01

    This paper describes the implementation of the instability analysis of wave growth on liquid jet surface, and maximum entropy principle (MEP) for prediction of droplet diameter distribution in primary breakup region. The early stage of the primary breakup, which contains the growth of wave on liquid-gas interface, is deterministic; whereas the droplet formation stage at the end of primary breakup is random and stochastic. The stage of droplet formation after the liquid bulk breakup can be modeled by statistical means based on the maximum entropy principle. The MEP provides a formulation that predicts the atomization process while satisfying constraint equations based on conservations of mass, momentum and energy. The deterministic aspect considers the instability of wave motion on jet surface before the liquid bulk breakup using the linear instability analysis, which provides information of the maximum growth rate and corresponding wavelength of instabilities in breakup zone. The two sub-models are coupled together using momentum source term and mean diameter of droplets. This model is also capable of considering drag force on droplets through gas-liquid interaction. The predicted results compared favorably with the experimentally measured droplet size distributions for hollow-cone sprays.

  16. Size distributions in urban aerosols

    SciTech Connect

    Lippmann, M.

    1980-01-01

    Data on the size distributions of urban aerosols are reviewed with emphasis on the physical characteristics of the particles. Types of size distributions, the reliability of size distribution data, and factors affecting urban aerosol size distributions are considered. As examples, the grand average number aerosol distribution from the 1969 Los Angeles smog experiment is compared with a Junge power law distribution calculated with the constants of Clark and Whitby. The computer-prepared volume size distribution measured during the General Motors Sulfate Study in Milford, Mich. is presented, the median size distribution by number for the New York Summer Aerosol Study is considered, and volume concentration distributions for Denver-area aerosols are presented.

  17. Analysis of the relationship between landslides size distribution and earthquake source area

    NASA Astrophysics Data System (ADS)

    Valagussa, Andrea; Crosta, Giovanni B.; Frattini, Paolo; Xu, Chong

    2014-05-01

    The spatial distribution of earthquake induced landslides around the seismogenetic source has been analysed to better understand the triggering of landslides in seismic areas and to forecast the maximum distance at which an earthquake, with a certain magnitude, can induce landslides (e.g Keefer, 1984). However, when applying such approaches to old earthquakes (e.g 1929 Buller and 1968 Iningahua earthquakes New Zealand; Parker, 2013; 1976 Friuli earthquake, Italy) one should be concerned about the undersampling of smaller landslides which can be cancelled by erosion and landscape evolution. For this reason, it is important to characterize carefully the relationship between landslide area and number with distance from the source, but also the size distribution of landslides as a function of distance from the source. In this paper, we analyse the 2008 Wenchuan earthquake landslide inventory (Xu et al, 2013). The earthquake triggered more than 197,000 landslides of different type, including rock avalanches, rockfalls, translational and rotational slides, lateral spreads and derbies flows. First, we calculated the landslide intensity (number of landslides per unit area) and spatial density (landslide area per unit area) as a function of distance from the source area of the earthquake. Then, we developed magnitude frequency curves (MFC) for different distances from the source area. Comparing these curves, we can describe the relation between the distance and the frequency density of landslide in seismic area. Keefer D K (1984) Landslides caused by earthquakes. Geological Society of America Bulletin, 95(4), 406-421. Parker R N, (2013) Hillslope memory and spatial and temporal distributions of earthquake-induced landslides, Durham theses, Durham University. Xu, C., Xu, X., Yao, X., & Dai, F. (2013). Three (nearly) complete inventories of landslides triggered by the May 12, 2008 Wenchuan Mw 7.9 earthquake of China and their spatial distribution statistical analysis

  18. Particles emitted from indoor combustion sources: size distribution measurement and chemical analysis.

    PubMed

    Roy, A A; Baxla, S P; Gupta, Tarun; Bandyopadhyaya, R; Tripathi, S N

    2009-08-01

    This study is primarily focused toward measuring the particle size distribution and chemical analysis of particulate matter that originates from combustion sources typically found in Indian urban homes. Four such sources were selected: cigarette, incense stick, mosquito coil, and dhoop, the latter being actually a thick form of incense stick. Altogether, seven of the most popular brands available in the Indian market were tested. Particle size distribution in the smoke was measured using a scanning mobility particle sizer, using both long and nano forms of differential mobility analyzer (DMA), with readings averaged from four to six runs. The measurable particle size range of the nano DMA was 4.6 nm to 157.8 nm, whereas that of the long DMA was 15.7 nm to 637.8 nm. Therefore, readings obtained from the long and the nano DMA were compared for different brands as well as for different sources. An overlap was seen in the readings in the common range of measurement. The lowest value of peak concentration was seen for one brand of incense stick (0.9 x 10(6) cm(-3)), whereas the highest (7.1 x 10(6) cm(-3)) was seen for the dhoop. Generally, these sources showed a peak between 140 and 170 nm; however, 2 incense stick brands showed peaks at 79 nm and 89 nm. The dhoop showed results much different from the rest of the sources, with a mode at around 240 nm. Chemical analysis in terms of three heavy metals (cadmium, zinc, and lead) was performed using graphite tube atomizer and flame-atomic absorption spectrophotometer. Calculations were made to assess the expected cancer and noncancer risks, using published toxicity potentials for these three heavy metals. Our calculations revealed that all the sources showed lead concentrations much below the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) level. One of the two mosquito coil brands (M(2)) showed cadmium concentrations two times higher than the California Environmental

  19. Assessing tephra total grain-size distribution: Insights from field data analysis

    NASA Astrophysics Data System (ADS)

    Costa, A.; Pioli, L.; Bonadonna, C.

    2016-06-01

    The Total Grain-Size Distribution (TGSD) of tephra deposits is crucial for hazard assessment and provides fundamental insights into eruption dynamics. It controls both the mass distribution within the eruptive plume and the sedimentation processes and can provide essential information on the fragmentation mechanisms. TGSD is typically calculated by integrating deposit grain-size at different locations. The result of such integration is affected not only by the number, but also by the spatial distribution and distance from the vent of the sampling sites. In order to evaluate the reliability of TGSDs, we assessed representative sampling distances for pyroclasts of different sizes through dedicated numerical simulations of tephra dispersal. Results reveal that, depending on wind conditions, a representative grain-size distribution of tephra deposits down to ∼100 μm can be obtained by integrating samples collected at distances from less than one tenth up to a few tens of the column height. The statistical properties of TGSDs representative of a range of eruption styles were calculated by fitting the data with a few general distributions given by the sum of two log-normal distributions (bi-Gaussian in Φ-units), the sum of two Weibull distributions, and a generalized log-logistic distribution for the cumulative number distributions. The main parameters of the bi-lognormal fitting correlate with height of the eruptive columns and magma viscosity, allowing general relationships to be used for estimating TGSD generated in a variety of eruptive styles and for different magma compositions. Fitting results of the cumulative number distribution show two different power law trends for coarse and fine fractions of tephra particles, respectively. Our results shed light on the complex processes that control the size of particles being injected into the atmosphere during volcanic explosive eruptions and represent the first attempt to assess TGSD on the basis of pivotal physical

  20. Comparison of particle size distribution data obtained with cascade impaction samplers and from Voulter counter analysis of total dust samples

    SciTech Connect

    Treaftis, H.N.; Kacsmar, P.; Suppers, K., Tomb, T.F.

    1986-02-01

    The paper discusses the results of a study conducted to evaluate two different methods used to measure the particle size distribution of an aerosol. Comparative samples were collected in the laboratory with Sierra's Models 260 and 298 cascade impaction samplers and a sampler consisting of a pump and filter using coal and limestone aerosols of varying particle size distributions. The particle size distributions determined from each of the impaction samples were compared to each other as well as to the particle size distribution determined from data obtained from a Coulter Counter analysis of the total dust sample collected on the filter. The results of the laboratory study are discussed and compared to a limited amount of similar data obtained from samples collected with the impaction samplers in underground coal mines.

  1. Interference from Proteins and Surfactants on Particle Size Distributions Measured by Nanoparticle Tracking Analysis (NTA).

    PubMed

    Bai, Kelvin; Barnett, Gregory V; Kar, Sambit R; Das, Tapan K

    2017-04-01

    Characterization of submicron protein particles continues to be challenging despite active developments in the field. NTA is a submicron particle enumeration technique, which optically tracks the light scattering signal from suspended particles undergoing Brownian motion. The submicron particle size range NTA can monitor in common protein formulations is not well established. We conducted a comprehensive investigation with several protein formulations along with corresponding placebos using NTA to determine submicron particle size distributions and shed light on potential non-particle origin of size distribution in the range of approximately 50-300 nm. NTA and DLS are performed on polystyrene size standards as well as protein and placebo formulations. Protein formulations filtered through a 20 nm filter, with and without polysorbate-80, show NTA particle counts. As such, particle counts above 20 nm are not expected in these solutions. Several other systems including positive and negative controls were studied using NTA and DLS. These apparent particles measured by NTA are not observed in DLS measurements and may not correspond to real particles. The intent of this article is to raise awareness about the need to interpret particle counts and size distribution from NTA with caution.

  2. Particle-Size Analysis

    SciTech Connect

    Gee, Glendon W. ); Or, Dani; J.H. Dane and G.C. Topp

    2002-11-01

    Book Chapter describing methods of particle-size analysis for soils. Includes a variety of classification schemes. Standard methods for size distributions using pipet and hydrometer techniques are described. New laser-light scattering and related techniques are discussed. Complete with updated references.

  3. Sieveless particle size distribution analysis of particulate materials through computer vision

    SciTech Connect

    Igathinathane, C.; Pordesimo, L. O.; Columbus, Eugene P; Batchelor, William D; Sokhansanj, Shahabaddine

    2009-05-01

    This paper explores the inconsistency of length-based separation by mechanical sieving of particulate materials with standard sieves, which is the standard method of particle size distribution (PSD) analysis. We observed inconsistencies of length-based separation of particles using standard sieves with manual measurements, which showed deviations of 17 22 times. In addition, we have demonstrated the falling through effect of particles cannot be avoided irrespective of the wall thickness of the sieve. We proposed and utilized a computer vision with image processing as an alternative approach; wherein a user-coded Java ImageJ plugin was developed to evaluate PSD based on length of particles. A regular flatbed scanner acquired digital images of particulate material. The plugin determines particles lengths from Feret's diameter and width from pixel-march method, or minor axis, or the minimum dimension of bounding rectangle utilizing the digital images after assessing the particles area and shape (convex or nonconvex). The plugin also included the determination of several significant dimensions and PSD parameters. Test samples utilized were ground biomass obtained from the first thinning and mature stand of southern pine forest residues, oak hard wood, switchgrass, elephant grass, giant miscanthus, wheat straw, as well as Basmati rice. A sieveless PSD analysis method utilized the true separation of all particles into groups based on their distinct length (419 639 particles based on samples studied), with each group truly represented by their exact length. This approach ensured length-based separation without the inconsistencies observed with mechanical sieving. Image based sieve simulation (developed separately) indicated a significant effect (P < 0.05) on number of sieves used in PSD analysis, especially with non-uniform material such as ground biomass, and more than 50 equally spaced sieves were required to match the sieveless all distinct particles PSD analysis

  4. Numerical simulation and sensitivity analysis of detailed soot particle size distribution in laminar premixed ethylene flames

    SciTech Connect

    Singh, Jasdeep; Patterson, Robert I.A.; Kraft, Markus; Wang, Hai

    2006-04-15

    In this paper, the prediction of a soot model [J. Appel, H. Bockhorn, M. Frenklach, Combust. Flame 121 (2000) 122-136] is compared to a recently published set of highly detailed soot particle size distributions [B. Zhao, Z. Yang, Z. Li, M.V. Johnston, H. Wang, Proc. Combust. Inst. 30 (2005)]. A stochastic approach is used to obtain soot particle size distributions (PSDs). The key features of the measured and simulated particle size distributions are identified and used as a simple way of comparing PSDs. The sensitivity of the soot PSDs to the parameters defining parts of the soot model, such as soot inception, particle and PAH collision efficiency and enhancement, and surface activity is investigated. Incepting soot particle size is found to have a very significant effect on the small-size end of the PSDs, especially the position of the trough for a bimodal soot PSDs. A new model for the decay in the surface activity is proposed in which the activity of the soot particle depends only on the history of that particle and the local temperature in the flame. This is a first attempt to use local flame variables to define the surface aging which has major impact on the prediction of the large-size end of the PSDs. Using these modifications to the soot model it is possible to improve the agreement between some of the points of interest in the simulated and measured PSDs. The paper achieves the task to help advance the soot models to predict soot PSD in addition to soot volume fraction and number density, which has been the focus of the literature. (author)

  5. Size-distribution analysis of proteins by analytical ultracentrifugation: strategies and application to model systems.

    PubMed Central

    Schuck, Peter; Perugini, Matthew A; Gonzales, Noreen R; Howlett, Geoffrey J; Schubert, Dieter

    2002-01-01

    Strategies for the deconvolution of diffusion in the determination of size-distributions from sedimentation velocity experiments were examined and developed. On the basis of four different model systems, we studied the differential apparent sedimentation coefficient distributions by the time-derivative method, g(s*), and by least-squares direct boundary modeling, ls-g*(s), the integral sedimentation coefficient distribution by the van Holde-Weischet method, G(s), and the previously introduced differential distribution of Lamm equation solutions, c(s). It is shown that the least-squares approach ls-g*(s) can be extrapolated to infinite time by considering area divisions analogous to boundary divisions in the van Holde-Weischet method, thus allowing the transformation of interference optical data into an integral sedimentation coefficient distribution G(s). However, despite the model-free approach of G(s), for the systems considered, the direct boundary modeling with a distribution of Lamm equation solutions c(s) exhibited the highest resolution and sensitivity. The c(s) approach requires an estimate for the size-dependent diffusion coefficients D(s), which is usually incorporated in the form of a weight-average frictional ratio of all species, or in the form of prior knowledge of the molar mass of the main species. We studied the influence of the weight-average frictional ratio on the quality of the fit, and found that it is well-determined by the data. As a direct boundary model, the calculated c(s) distribution can be combined with a nonlinear regression to optimize distribution parameters, such as the exact meniscus position, and the weight-average frictional ratio. Although c(s) is computationally the most complex, it has the potential for the highest resolution and sensitivity of the methods described. PMID:11806949

  6. Analysis of stratocumulus cloud fields using LANDSAT imagery: Size distributions and spatial separations

    NASA Technical Reports Server (NTRS)

    Welch, R. M.; Sengupta, S. K.; Chen, D. W.

    1990-01-01

    Stratocumulus cloud fields in the FIRE IFO region are analyzed using LANDSAT Thematic Mapper imagery. Structural properties such as cloud cell size distribution, cell horizontal aspect ratio, fractional coverage and fractal dimension are determined. It is found that stratocumulus cloud number densities are represented by a power law. Cell horizontal aspect ratio has a tendency to increase at large cell sizes, and cells are bi-fractal in nature. Using LANDSAT Multispectral Scanner imagery for twelve selected stratocumulus scenes acquired during previous years, similar structural characteristics are obtained. Cloud field spatial organization also is analyzed. Nearest-neighbor spacings are fit with a number of functions, with Weibull and Gamma distributions providing the best fits. Poisson tests show that the spatial separations are not random. Second order statistics are used to examine clustering.

  7. Bubble size distribution analysis and control in high frequency ultrasonic cleaning processes

    NASA Astrophysics Data System (ADS)

    Hauptmann, M.; Struyf, H.; Mertens, P.; Heyns, M.; De Gendt, S.; Glorieux, C.; Brems, S.

    2012-12-01

    In the semiconductor industry, the ongoing down-scaling of nanoelectronic elements has lead to an increasing complexity of their fabrication. Hence, the individual fabrication processes become increasingly difficult to handle. To minimize cross-contamination, intermediate surface cleaning and preparation steps are inevitable parts of the semiconductor process chain. Here, one major challenge is the removal of residual nano-particulate contamination resulting from abrasive processes such as polishing and etching. In the past, physical cleaning techniques such as megasonic cleaning have been proposed as suitable solutions. However, the soaring fragility of the smallest structures is constraining the forces of the involved physical removal mechanisms. In the case of "megasonic" cleaning -cleaning with ultrasound in the MHz-domain - the main cleaning action arises from strongly oscillating microbubbles which emerge from the periodically changing tensile strain in the cleaning liquid during sonication. These bubbles grow, oscillate and collapse due to a complex interplay of rectified diffusion, bubble coalescence, non-linear pulsation and the onset of shape instabilities. Hence, the resulting bubble size distribution does not remain static but alternates continuously. Only microbubbles in this distribution that show a high oscillatory response are responsible for the cleaning action. Therefore, the cleaning process efficiency can be improved by keeping the majority of bubbles around their resonance size. In this paper, we propose a method to control and characterize the bubble size distribution by means of "pulsed" sonication and measurements of acoustic cavitation spectra, respectively. We show that the so-obtained bubble size distributions can be related to theoretical predictions of the oscillatory responses of and the onset of shape instabilities for the respective bubbles. We also propose a mechanism to explain the enhancement of both acoustic and cleaning activity

  8. Cumulative frequency fit for particle size distribution.

    PubMed

    Xu, Zhuyun; Gautam, Mridul; Mehta, Sandeep

    2002-08-01

    A cumulative frequency distribution fit method is presented for analyzing particle size distributions by minimizing the summation of the square of cumulative frequency errors. Compared to the frequency fit method, the cumulative frequency fit method yields a more accurate solution. Based upon this, a spreadsheet was developed for analyzing multi-modal particle size distribution. The motivation for the work presented in this article was the current interest in ultra-fine and nano-sized particle exhaust emissions from heavy-duty diesel engines. The new spreadsheet provides a quick and convenient way to conduct particle size distribution analysis.

  9. Analysis of indoor particle size distributions in an occupied townhouse using positive matrix factorization.

    PubMed

    Ogulei, D; Hopke, P K; Wallace, L A

    2006-06-01

    From late 1999 to early March 2000, measurements of particle number (particles 0.01-20 microm in aerodynamic diameter) concentrations were made inside of a townhouse occupied by two non-smoking adults and located in Reston, VA (approximately 25 miles northwest of Washington, DC). The particle size measurements were made using an SMPS and an APS as well as a Climet optical scattering instrument. In this study, positive matrix factorization (PMF) was used to study the indoor particle size distributions. The size distributions or profiles obtained were identified by relating the obtained source contributions to the source information provided by the occupants. Nine particle sources were identified, including two sources associated with gas burner use: boiling water and frying tortillas. Boiling water for tea or coffee was found to be associated only with the smallest particles, with a number mode close to the detection limit of the SMPS (i.e., 0.01 microm). Frying tortillas produced particles with a number mode at about 0.09 microm while broiling fish produced particles with a number mode at about 0.05 microm. A citronella candle was often burned during the study period, and this practice was found to produce a 0.2-microm modal number distribution. Other indoor particle sources identified included sweeping/vacuuming (volume mode at 2 microm); use of the electric toaster oven (number mode at 0.03 microm); and pouring of kitty litter (volume mode over 10 microm). Two outdoor sources were also resolved: traffic (number mode at about 0.15 microm) and wood smoke (major number mode at about 0.07 microm). The volume distributions showed presence of coarse particles in most of the resolved indoor sources probably caused by personal cloud emissions as the residents performed the various indoor activities. This study has shown that continuous measurements of indoor particle number and volume concentrations together with records of personal activities are useful for indoor

  10. Meta-analysis using effect size distributions of only statistically significant studies.

    PubMed

    van Assen, Marcel A L M; van Aert, Robbie C M; Wicherts, Jelte M

    2015-09-01

    Publication bias threatens the validity of meta-analytic results and leads to overestimation of the effect size in traditional meta-analysis. This particularly applies to meta-analyses that feature small studies, which are ubiquitous in psychology. Here we develop a new method for meta-analysis that deals with publication bias. This method, p-uniform, enables (a) testing of publication bias, (b) effect size estimation, and (c) testing of the null-hypothesis of no effect. No current method for meta-analysis possesses all 3 qualities. Application of p-uniform is straightforward because no additional data on missing studies are needed and no sophisticated assumptions or choices need to be made before applying it. Simulations show that p-uniform generally outperforms the trim-and-fill method and the test of excess significance (TES; Ioannidis & Trikalinos, 2007b) if publication bias exists and population effect size is homogenous or heterogeneity is slight. For illustration, p-uniform and other publication bias analyses are applied to the meta-analysis of McCall and Carriger (1993) examining the association between infants' habituation to a stimulus and their later cognitive ability (IQ). We conclude that p-uniform is a valuable technique for examining publication bias and estimating population effects in fixed-effect meta-analyses, and as sensitivity analysis to draw inferences about publication bias. (c) 2015 APA, all rights reserved).

  11. City-size distribution and the size of urban systems.

    PubMed

    Thomas, I

    1985-07-01

    "This paper is an analysis of the city-size distribution for thirty-five countries of the world in 1975; the purpose is to explain statistically the regularity of the rank-size distribution by the number of cities included in the urban systems. The rank-size parameters have been computed for each country and also for four large urban systems in which several population thresholds have been defined. These thresholds seem to have more influence than the number of cities included in the urban system on the regularity of the distribution." The data are from the U.N. Demographic Yearbook. excerpt

  12. Automated system for kinetic analysis of particle size distributions for pharmaceutically relevant systems.

    PubMed

    Green, John-Bruce D; Carter, Phillip W; Zhang, Yingqing; Patel, Dipa; Kotha, Priyanka; Gonyon, Thomas

    2014-01-01

    Detailing the kinetics of particle formation for pharmaceutically relevant solutions is challenging, especially when considering the combination of formulations, containers, and timescales of clinical importance. This paper describes a method for using commercial software Automate with a stream-selector valve capable of sampling container solutions from within an environmental chamber. The tool was built to monitor changes in particle size distributions via instrumental particle counters but can be adapted to other solution-based sensors. The tool and methodology were demonstrated to be highly effective for measuring dynamic changes in emulsion globule distributions as a function of storage and mixing conditions important for parenteral nutrition. Higher levels of agitation induced the fastest growth of large globules (≥5 μm) while the gentler conditions actually showed a decrease in the number of these large globules. The same methodology recorded calcium phosphate precipitation kinetics as a function of [Ca(2+)] and pH. This automated system is readily adaptable to a wide range of pharmaceutically relevant systems where the particle size is expected to vary with time. This instrumentation can dramatically reduce the time and resources needed to probe complex formulation issues while providing new insights for monitoring the kinetics as a function of key variables.

  13. Automated System for Kinetic Analysis of Particle Size Distributions for Pharmaceutically Relevant Systems

    PubMed Central

    Green, John-Bruce D.; Carter, Phillip W.; Zhang, Yingqing; Patel, Dipa; Kotha, Priyanka

    2014-01-01

    Detailing the kinetics of particle formation for pharmaceutically relevant solutions is challenging, especially when considering the combination of formulations, containers, and timescales of clinical importance. This paper describes a method for using commercial software Automate with a stream-selector valve capable of sampling container solutions from within an environmental chamber. The tool was built to monitor changes in particle size distributions via instrumental particle counters but can be adapted to other solution-based sensors. The tool and methodology were demonstrated to be highly effective for measuring dynamic changes in emulsion globule distributions as a function of storage and mixing conditions important for parenteral nutrition. Higher levels of agitation induced the fastest growth of large globules (≥5 μm) while the gentler conditions actually showed a decrease in the number of these large globules. The same methodology recorded calcium phosphate precipitation kinetics as a function of [Ca2+] and pH. This automated system is readily adaptable to a wide range of pharmaceutically relevant systems where the particle size is expected to vary with time. This instrumentation can dramatically reduce the time and resources needed to probe complex formulation issues while providing new insights for monitoring the kinetics as a function of key variables. PMID:25140276

  14. Size exclusion chromatography-multiangle laser light scattering analysis of hyaluronan size distributions made by membrane-bound hyaluronan synthase.

    PubMed

    Baggenstoss, Bruce A; Weigel, Paul H

    2006-05-15

    Size exclusion chromatography-multiangle laser light scattering (SEC-MALLS) analyses of Escherichia coli membranes expressing Streptococcus equisimilis hyaluronan synthase (seHAS) demonstrated an inherent artifact (10-100 MDa) that coeluted with hyaluronan (HA) and skewed the apparent weight-average mass of HA to erroneously high values. Briefly heating samples to 65-75 degrees C eliminated this artifact and increased the yield of recovered HA due to the release of HA chains that were attached to membrane-bound HAS. Inclusion of alkaline phosphatase, which removed uridine 5'-diphosphate (UDP) produced during the reaction, improved the linearity of HA synthesis-even at high substrate use. Surprisingly, the addition of EDTA, to chelate Mg(2+) ions, did not completely stop the HAS reaction at 30 degrees C or at 4 degrees C. The best conditions for stopping the reaction without altering SEC-MALLS profiles of the product HA were to chill samples on ice in the presence of both EDTA and UDP. Even with excess substrate, the maximum size of product HA decreased as the enzyme concentration increased. Therefore, the maximum HA size made by HAS was determined by extrapolation to zero enzyme concentration. Using the above conditions, membrane-bound seHAS synthesized a cohort of HA products that steadily increased in weight-average molar mass, reaching a final maximal steady-state size of 4 to 6 MDa within 2-4 h.

  15. Centaur size distribution with DECam

    NASA Astrophysics Data System (ADS)

    Fuentes, Cesar; Trilling, David E.; Schlichting, Hilke

    2014-11-01

    We present the results of the 2014 centaur search campaign on the Dark Energy Camera (DECam) in Tololo, Chile. This is the largest debiased Centaur survey to date, measuring for the first time the size distribution of small Centaurs (1-10km) and the first time the sizes of planetesimals from which the entire Solar System formed are directly detected.The theoretical model for the coagulation and collisional evolution of the outer solar system proposed in Schlichting et al. 2013 predicts a steep rise in the size distribution of TNOs smaller than 10km. These objects are below the detection limit of current TNO surveys but feasible for the Centaur population. By constraining the number of Centaurs and this feature in their size distribution we can confirm the collisional evolution of the Solar System and estimate the rate at which material is being transferred from the outer to the inner Solar System. If the shallow power law behavior from the TNO size distribution at ~40km can be extrapolated to 1km, the size of the Jupiter Family of Comets (JFC), there would not be enough small TNOs to supply the JFC population (Volk & Malhotra, 2008), debunking the link between TNOs and JFCs.We also obtain the colors of small Centaurs and TNOs, providing a signature of collisional evolution by measuring if there is in fact a relationship between color and size. If objects smaller than the break in the TNO size distribution are being ground down by collisions then their surfaces should be fresh, and then appear bluer in the optical than larger TNOs that are not experiencing collisions.

  16. Measurement of the aerosol size distribution with NRL's mobility analyzer

    NASA Technical Reports Server (NTRS)

    Hoppel, W. A.

    1981-01-01

    The size distribution was measured in the size range between 0.0057 and 0.57 micrometer radius. A description of the instrumentation and data analysis is given, together with the measured size distributions calculated for 23 experiments.

  17. Comparative analysis of raindrop size distribution between southern Korea and Norman, Oklahoma

    NASA Astrophysics Data System (ADS)

    Lee, GyuWon; Bang, WanBae; Ryzhkov, Alexander; Schuur, Terry

    2017-04-01

    The particle size distributions (PSD) are key component to describe microphysical processes and furthermore to predict precipitation amount in numerical weather prediction. PSDs vary from storm to strom and depends on different climatic regimes. The variation of PSD causes significant uncertainty in retrieval techniques in remote sensing, precipitation estimation, and forecasting. In this study, the characteristics of PSD are examined in two regions (East Asia: Daegu city, DG and North America: Oklahoma city, OK) using radar measurement and microphysical parameters such as intercept parameter (Nw), mass-weighted mean diameter (Dm), rainfall intensity (R), and average PSDs derived from distrometric measurement. 2-dimensional Video Distrometer (2DVD) data are obtained from rain cases during 2011-2012 year in DG and during 1998-2006 year in OK. The microphysical parameters (Nw, Dm, R) are calculated by moment (Mn) method. The probability density functions of these parameters and average PSDs are compared as functions of different reflectivity (Z). PSD from DG has relatively large Nw and small Dm, whereas that of OK is characterized by small Nw and large Dm. The differences are noticeable when Z >35 dBZ. This indicates that dominant microphysical process of heavy rain differs from DG and OK. We will explore possible microphysical processes that are responsible for the difference.

  18. Assessment of particulate matter in the urban atmosphere: size distribution, metal composition and source characterization using principal component analysis.

    PubMed

    Onat, Burcu; Alver Şahin, Ülkü; Bayat, Cuma

    2012-05-01

    In this study, the size distribution of airborne particles and related heavy metals Co, Cd, Sn, Cu, Ni, Cr, Pb and V in two urban areas in Istanbul: Yenibosna and Goztepe, were examined. The different inhalable particles were collected by using a cascade impactor in eight size fractions (<0.4 μm, 0.4-0.7 μm, 1.1-2.1 μm, 2.1-3.3 μm, 3.3-4.7 μm, 4.7-5.8 μm, 5.8-9 μm and >9 μm) for six months at each station. Samples were collected on glass fiber filters and filters were extracted and analyzed using ICP-MS. Log-normal distributions showed that the particles collected at the Yenibosna site have a smaller size compared to the Goztepe samples and the size distribution of PM was represented the best by the tri-modal. The average total particle concentrations and standard deviations were obtained as 67.7 ± 17.0 μg m(-3) and 82.1 ± 21.2 μg m(-3), at the Yenibosna and Göztepe sites, respectively. The higher metal rate in fine and medium coarse PM showed that the anthropogenic sources were the most significant pollutant source. Principal component analysis identified five components for PM namely traffic, road dust, coal and fuel oil combustion, and industrial.

  19. Assessment of optimum threshold and particle shape parameter for the image analysis of aggregate size distribution of concrete sections

    NASA Astrophysics Data System (ADS)

    Ozen, Murat; Guler, Murat

    2014-02-01

    Aggregate gradation is one of the key design parameters affecting the workability and strength properties of concrete mixtures. Estimating aggregate gradation from hardened concrete samples can offer valuable insights into the quality of mixtures in terms of the degree of segregation and the amount of deviation from the specified gradation limits. In this study, a methodology is introduced to determine the particle size distribution of aggregates from 2D cross sectional images of concrete samples. The samples used in the study were fabricated from six mix designs by varying the aggregate gradation, aggregate source and maximum aggregate size with five replicates of each design combination. Each sample was cut into three pieces using a diamond saw and then scanned to obtain the cross sectional images using a desktop flatbed scanner. An algorithm is proposed to determine the optimum threshold for the image analysis of the cross sections. A procedure was also suggested to determine a suitable particle shape parameter to be used in the analysis of aggregate size distribution within each cross section. Results of analyses indicated that the optimum threshold hence the pixel distribution functions may be different even for the cross sections of an identical concrete sample. Besides, the maximum ferret diameter is the most suitable shape parameter to estimate the size distribution of aggregates when computed based on the diagonal sieve opening. The outcome of this study can be of practical value for the practitioners to evaluate concrete in terms of the degree of segregation and the bounds of mixture's gradation achieved during manufacturing.

  20. Size distribution of ring polymers

    PubMed Central

    Medalion, Shlomi; Aghion, Erez; Meirovitch, Hagai; Barkai, Eli; Kessler, David A.

    2016-01-01

    We present an exact solution for the distribution of sample averaged monomer to monomer distance of ring polymers. For non-interacting and local-interaction models these distributions correspond to the distribution of the area under the reflected Bessel bridge and the Bessel excursion respectively, and are shown to be identical in dimension d ≥ 2, albeit with pronounced finite size effects at the critical dimension, d = 2. A symmetry of the problem reveals that dimension d and 4 − d are equivalent, thus the celebrated Airy distribution describing the areal distribution of the d = 1 Brownian excursion describes also a polymer in three dimensions. For a self-avoiding polymer in dimension d we find numerically that the fluctuations of the scaled averaged distance are nearly identical in dimension d = 2, 3 and are well described to a first approximation by the non-interacting excursion model in dimension 5. PMID:27302596

  1. Statistical Analysis of Streambed Sediment Grain Size Distributions: Implications for Environmental Management and Regulatory Policy

    Treesearch

    Brenda Rosser; Matt O' Connor

    2007-01-01

    Fish habitat in cold water streams in many northwestern California watersheds has been declared degraded under provisions of the Federal Clean Water Act, contributing to listings of anadromous fish species under the Endangered Species Act. It is believed that past and present land management activities induce erosion that contributes excess sand-size and finer sediment...

  2. SEC-MALLS ANALYSIS OF HYALURONAN SIZE DISTRIBUTIONS MADE BY MEMBRANE-BOUND HYALURONAN SYNTHASE

    PubMed Central

    Baggenstoss, Bruce A.; Weigel, Paul H.

    2006-01-01

    SEC-MALLS analyses of E. coli membranes expressing Streptococcus equisimilis hyaluronan synthase (seHAS) demonstrated an inherent artifact (10–100 MDa) that co-eluted with HA, and skewed the apparent weight-average mass of HA to erroneously high values. Briefly heating samples to 65–75°C eliminated this artifact and increased the yield of recovered HA, due to the release of HA chains that were attached to membrane-bound HAS. Inclusion of alkaline phosphatase, which removed UDP produced during the reaction, improved the linearity of HA synthesis - even at high substrate utilization. Surprisingly, addition of EDTA, to chelate Mg+2 ions, did not completely stop the HAS reaction at 30°C or at 4°C. The best conditions for stopping the reaction without altering SEC-MALLS profiles of the product HA were to chill samples on ice in the presence of both EDTA and UDP. Even with excess substrate, the maximum size of product HA decreased as the enzyme concentration increased. Therefore, the maximum HA size made by HAS was determined by extrapolation to zero enzyme concentration. Using the above conditions, membrane-bound seHAS synthesized a cohort of HA products that steadily increased in weight-average molar mass, reaching a final maximal steady-state size of 4–6 MDa within 2–4 hours. PMID:16476403

  3. Exponential Size Distribution of von Willebrand Factor

    PubMed Central

    Lippok, Svenja; Obser, Tobias; Müller, Jochen P.; Stierle, Valentin K.; Benoit, Martin; Budde, Ulrich; Schneppenheim, Reinhard; Rädler, Joachim O.

    2013-01-01

    Von Willebrand Factor (VWF) is a multimeric protein crucial for hemostasis. Under shear flow, it acts as a mechanosensor responding with a size-dependent globule-stretch transition to increasing shear rates. Here, we quantify for the first time, to our knowledge, the size distribution of recombinant VWF and VWF-eGFP using a multilateral approach that involves quantitative gel analysis, fluorescence correlation spectroscopy, and total internal reflection fluorescence microscopy. We find an exponentially decaying size distribution of multimers for recombinant VWF as well as for VWF derived from blood samples in accordance with the notion of a step-growth polymerization process during VWF biosynthesis. The distribution is solely described by the extent of polymerization, which was found to be reduced in the case of the pathologically relevant mutant VWF-IIC. The VWF-specific protease ADAMTS13 systematically shifts the VWF size distribution toward smaller sizes. This dynamic evolution is monitored using fluorescence correlation spectroscopy and compared to a computer simulation of a random cleavage process relating ADAMTS13 concentration to the degree of VWF breakdown. Quantitative assessment of VWF size distribution in terms of an exponential might prove to be useful both as a valuable biophysical characterization and as a possible disease indicator for clinical applications. PMID:24010664

  4. Coupling gravitational and flow field-flow fractionation, and size-distribution analysis of whole yeast cells.

    PubMed

    Sanz, Ramsés; Puignou, Lluís; Galceran, Maria Teresa; Reschiglian, Pierluigi; Zattoni, Andrea; Melucci, Dora

    2004-08-01

    This work continues the project on field-flow fractionation characterisation of whole wine-making yeast cells reported in previous papers. When yeast cells are fractionated by gravitational field-flow fractionation and cell sizing of the collected fractions is achieved by the electrosensing zone technique (Coulter counter), it is shown that yeast cell retention depends on differences between physical indexes of yeast cells other than size. Scanning electron microscopy on collected fractions actually shows co-elution of yeast cells of different size and shape. Otherwise, the observed agreement between the particle size distribution analysis obtained by means of the Coulter counter and by flow field-flow fractionation, which employs a second mobile phase flow as applied field instead of Earth's gravity, indicates that yeast cell density can play a major role in the gravitational field-flow fractionation retention mechanism of yeast cells, in which flow field-flow fractionation retention is independent of particle density. Flow field-flow fractionation is then coupled off-line to gravitational field-flow fractionation for more accurate characterisation of the doubly-fractionated cells. Coupling gravitational and flow field-flow fractionation eventually furnishes more information on the multipolydispersity indexes of yeast cells, in particular on their shape and density polydispersity.

  5. A Hierarchical Cluster end-member modeling analysis (CEMMA) for searching unmixing Grain-size Distributions in Sediments

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Zhou, A.; Wang, X.; Zhao, Y.; Xie, H.; Chen, F.

    2016-12-01

    Sediments' grain-size distribution (GSD) analysis, as one of the most widely used proxies in sedimentary environmental and paleoclimatological studies, provides direct and abundant information on the process of deposition as well as sedimentary environment. Numerous studies have employed various parameters of GSD to infer including hydrodynamic condition, dust activity and deposition source of sediments, while most analytical methods just analyze parts of the distributions, hindering their wide extrapolation. End-member modeling analysis (EMMA) provides a flexible method for unmixing GSD. However, many issues still remain unresolved using existing EMMA method. Here we present a hierarchical cluster end-member modeling analysis (CEMMA) for searching unmixing GSD in sediments. Within the cluster framework, the number of end-members can be inferred by the agglomeration schedule, while end-member spectra are searched out based on the average distance of samples in the clusters. We use nonnegative constrained least-squares algorithm to calculate the scores of each end-member. To test the CEMMA method, a real-world dataset of lake sediments derived from Wulungu Lake was run. Turned out that this CEMMA method can yield geologically and mathematically meaningful output, thereby is a fast and flexible approach for GSD analysis. For the convenience of every researcher, all the algorithms of this method have been written in a package named CEM which could be edited and run in software Matlab.

  6. Analysis of a Stochastic Model for Bacterial Growth and the Lognormality of the Cell-Size Distribution

    NASA Astrophysics Data System (ADS)

    Yamamoto, Ken; Wakita, Jun-ichi

    2016-07-01

    This paper theoretically analyzes a phenomenological stochastic model for bacterial growth. This model comprises cell division and the linear growth of cells, where growth rates and cell cycles are drawn from lognormal distributions. We find that the cell size is expressed as a sum of independent lognormal variables. We show numerically that the quality of the lognormal approximation greatly depends on the distributions of the growth rate and cell cycle. Furthermore, we show that actual parameters of the growth rate and cell cycle take values that give a good lognormal approximation; thus, the experimental cell-size distribution is in good agreement with a lognormal distribution.

  7. Distribution and determinants of eye size and shape in newborn children: a magnetic resonance imaging analysis.

    PubMed

    Lim, Laurence Shen; Chong, Gim Hong; Tan, Pei Ting; Chong, Yap-Seng; Kwek, Kenneth; Gluckman, Peter D; Fortier, Marielle V; Saw, Seang-Mei; Qiu, Anqi

    2013-07-16

    To determine the eye size and shape obtained by magnetic resonance imaging (MRI), and to determine associations with antenatal factors in newborn children. A subset of 173 full-term newborn children from the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) birth cohort underwent MRI. Eye volume and surface area were measured. Eye shape was assessed qualitatively from three-dimensional models, and quantitatively by measurement of longitudinal axial length (AL, the length from the posterior corneal surface to the retinal surface), and horizontal width and vertical height of the internal eye along the cardinal axes. Oblateness was calculated as 1-(AL/width) or 1-(AL/height). Oblate eyes had oblateness>+0.01, spherical eyes had oblateness between +0.01 and -0.01, and prolate eyes had oblateness<-0.01. A total of 346 eyes of 173 children were included. Mean oblateness using width was -0.06±0.05 (range, -0.23 to +0.08), and mean oblateness using height was -0.01±0.04 (range, -0.19 to +0.13). Using width, most eyes were prolate (294 eyes, 85%); and using height, the largest proportion of eyes was prolate (163 eyes, 47%). Eyes with longer ALs had greater widths, heights, volumes, and surface areas than eyes with shorter ALs (P<0.001 for all). With increasing AL, eyes became increasingly prolate. Children of less educated mothers had longer ALs (P=0.02). Malay children had larger eye volumes and surface areas than Chinese or Indian children. Most newborn Singaporean Asian children are born with prolate eyes. A longitudinal study is required to determine if globe shape at birth influences subsequent refractive changes.

  8. Automated quantitative 3D analysis of aorta size, morphology, and mural calcification distributions

    SciTech Connect

    Kurugol, Sila Come, Carolyn E.; Diaz, Alejandro A.; Ross, James C.; Washko, George R.; San Jose Estepar, Raul; Kinney, Greg L.; Black-Shinn, Jennifer L.; Hokanson, John E.; Budoff, Matthew J.

    2015-09-15

    Purpose: The purpose of this work is to develop a fully automated pipeline to compute aorta morphology and calcification measures in large cohorts of CT scans that can be used to investigate the potential of these measures as imaging biomarkers of cardiovascular disease. Methods: The first step of the automated pipeline is aorta segmentation. The algorithm the authors propose first detects an initial aorta boundary by exploiting cross-sectional circularity of aorta in axial slices and aortic arch in reformatted oblique slices. This boundary is then refined by a 3D level-set segmentation that evolves the boundary to the location of nearby edges. The authors then detect the aortic calcifications with thresholding and filter out the false positive regions due to nearby high intensity structures based on their anatomical location. The authors extract the centerline and oblique cross sections of the segmented aortas and compute the aorta morphology and calcification measures of the first 2500 subjects from COPDGene study. These measures include volume and number of calcified plaques and measures of vessel morphology such as average cross-sectional area, tortuosity, and arch width. Results: The authors computed the agreement between the algorithm and expert segmentations on 45 CT scans and obtained a closest point mean error of 0.62 ± 0.09 mm and a Dice coefficient of 0.92 ± 0.01. The calcification detection algorithm resulted in an improved true positive detection rate of 0.96 compared to previous work. The measurements of aorta size agreed with the measurements reported in previous work. The initial results showed associations of aorta morphology with calcification and with aging. These results may indicate aorta stiffening and unwrapping with calcification and aging. Conclusions: The authors have developed an objective tool to assess aorta morphology and aortic calcium plaques on CT scans that may be used to provide information about the presence of cardiovascular

  9. PM10 size distribution of metals and environmental-sanitary risk analysis in the city of Torino.

    PubMed

    Romanazzi, Valeria; Casazza, Marco; Malandrino, Mery; Maurino, Valter; Piano, Angelo; Schilirò, Tiziana; Gilli, Giorgio

    2014-10-01

    The mechanisms responsible for negative biological effects due to airborne particulate matter (PM) exposure are still being studied, however the interactions between metals and biologic systems seem to be of primary importance. The aim of the study was to estimate a healthy risk linked to exposure to airborne PM10 metals by means of an environmental-sanitary risk assessment. Metals PM10 size distribution analysis was carried out in a central site of Torino city - Italy, then the Target Hazard Quotient (THQ) and the Cancer Risk (CR) were applied, according to standard EPA methods. All sampled metals were present on the different PM10 fractions, however some metals were distributed in some specific fractions: ANOVA test shows Cr, Cu, Mo and Pb as differently distributed among the eight fractions, rising the hypothesis of potential effects in specific tracts of respiratory system. Regarding the risk assessment, in general the CR was higher for an adult than for a child, conversely the THQ resulted higher for a child. While the concentrations of all the sampled metals appeared to be under control, their presence in the different PM10 fractions and their THQ and CR provided indications related to the body districts potentially in contact with these substances.

  10. Planetary surface dating from crater size-frequency distribution measurements: Poisson timing analysis

    NASA Astrophysics Data System (ADS)

    Michael, G. G.; Kneissl, T.; Neesemann, A.

    2016-10-01

    The predictions of crater chronology models have customarily been evaluated by dividing a crater population into discrete diameter intervals, plotting the crater density for each, and finding a best-fit model isochron, with the uncertainty in the procedure being assessed using 1/√n estimates, where n is the number of craters in an interval. This approach yields an approximate evaluation of the model predictions. The approximation is good until n becomes small, hence the often-posed question: what is the minimum number of craters for an adequate prediction? This work introduces an approach for exact evaluation of a crater chronology model using Poisson statistics and Bayesian inference, expressing the result as a likelihood function with an intrinsic uncertainty. We demonstrate that even in the case of no craters at all, a meaningful likelihood function can be obtained. Thus there is no required minimum count: there is only varying uncertainty, which can be well described. We recommend that the Poisson timing analysis should be preferred over binning/best-fit approaches. Additionally, we introduce a new notation to make it consistently clear that crater chronology model calibration errors are inseparable from stated crater model ages and their associated statistical errors.

  11. Laboratory measurements to determine the grain size distribution of a sand-gravel bed surface and substrate: image analysis and CT scanner analysis

    NASA Astrophysics Data System (ADS)

    Orru, C.; Blom, A.; Uijttewaal, W.

    2012-12-01

    Spatial and temporal changes in the grain size distribution are crucial to describe sediment transport and the related grain size selective processes. Two complimentary laboratory techniques are presented to determine such variations of the grain size distribution of the bed surface and substrate: (1) particle coloring in combination with photogrammetric analysis, and (2) core sampling combined with three-dimensional imaging. The two techniques will be used in later flume experiments that are aimed at studying the response of the river bed to nonsteady boundary conditions. In these flume experiments, the bed surface and substrate grain size distribution needs to be measured using reliable and preferentially rapid techniques. The techniques were evaluated conducting an experiment that partially reproduced the conditions of the later flume experiments. Three nonoverlapping grain size fractions (i.e. within the range of coarse sand to fine gravel) were used and they were painted in different colors. Various mixtures of the three grain size fractions were composed of various color combinations. Patches of the mixtures were installed in a pool. Images were taken of the bed surface and the images were analyzed using an algorithm based on color segmentation. The algorithm provides values of the surface fraction of the bed covered by a certain color (i.e. a size fraction). The influence of water depth on the results of the image analysis was studied. To this end pictures were taken without water and for three water depths. The image analysis results shows that the technique can be used effectively for images of the bed in a flume filled with water. This is beneficiary in applying the technique in the later flume experiments. The second technique comprises core sampling in combination with three-dimensional imaging. Samples taken with tube cores were fixed with wallpaper glue and analyzed using a micro computed tomography scanner (micro CT scanner). The scans provide a

  12. An improved size exclusion-HPLC method for molecular size distribution analysis of immunoglobulin G using sodium perchlorate in the eluent.

    PubMed

    Wang, Hsiaoling; Levi, Mark S; Del Grosso, Alfred V; McCormick, William M; Bhattacharyya, Lokesh

    2017-05-10

    Size exclusion (SE) high performance liquid chromatography (HPLC) is widely used for the molecular size distribution (MSD) analyses of various therapeutic proteins. We report development and validation of a SE-HPLC method for MSD analyses of immunoglobulin G (IgG) in products using a TSKgel SuperSW3000 column and eluting it with 0.4M NaClO4, a chaotropic salt, in 40mM phosphate buffer, pH 6.8. The chromatograms show distinct peaks of aggregates, tetramer, and two dimers, as well as the monomer and fragment peaks. In addition, the method offers about half the run time (12min), better peak resolution, improved peak shape and more stable base-line compared to HPLC methods reported in the literature, including that in the European Pharmacopeia (EP). A comparison of MSD analysis results between our method and the EP method shows interactions between the protein and the stationary phase and partial adsorption of aggregates and tetramer on the stationary phase, when the latter method is used. Thus, the EP method shows lower percent of aggregates and tetramer than are actually present in the products. In view of the fact that aggregates have been attributed to playing a critical role in adverse reactions due to IgG products, our observation raises a major concern regarding the actual aggregate content in these products since the EP method is widely used for MSD analyses of IgG products. Our method eliminates (or substantially reduces) the interactions between the proteins and stationary phase as well as the adsorption of proteins onto the column. Our results also show that NaClO4 in the eluent is more effective in overcoming the protein/column interactions compared to Arg-HCl, another chaotropic salt. NaClO4 is shown not to affect the molecular size and relative distribution of different molecular forms of IgG. The method validated as per ICH Q2(R1) guideline using IgG products, shows good specificity, accuracy, precision and a linear concentration dependence of peak areas

  13. Aerosol and air pollution size distribution

    NASA Astrophysics Data System (ADS)

    Shani, Gad; Haccoun, A.; Kushelevsky, A.

    The size distribution of aerosols was measured in a moderately industrial city, in a semi-arid zone on the Negev desert border. The aerosols in the city of Beer Sheva are from two sources: the dust coming from the desert and urban pollution. The size measurements were done with a cascade impactor. The elemental content of the aerosols was investigated by neutron activation analysis and X-ray fluorescence. The main elements of the dust are: Ca, Si, Fe, Na and the trace elements are: Sc, Se, La, Sm, Hf and others. The main elements of the urban pollution are S, Br, Pb, Cl, Hg and others. It was found that the elements belonging to each group can easily be classified by the size distribution. The analytical consideration of the aerosol size distribution of each group are discussed and two corresponding analytical expressions are suggested. It is shown that aerosols originating in the dust have a hump shape distribution around ~ 4μm, and those originating in urban pollution have a distribution decreasing with increasing aerosol diameter. Many examples are given to prove the conclusions.

  14. Analysis of field size distributions, LACIE test sites 5029, 5033, and 5039, Anhwei Province, People's Republic of China

    NASA Technical Reports Server (NTRS)

    Podwysocki, M. H.

    1976-01-01

    A study was made of the field size distributions for LACIE test sites 5029, 5033, and 5039, People's Republic of China. Field lengths and widths were measured from LANDSAT imagery, and field area was statistically modeled. Field size parameters have log-normal or Poisson frequency distributions. These were normalized to the Gaussian distribution and theoretical population curves were made. When compared to fields in other areas of the same country measured in the previous study, field lengths and widths in the three LACIE test sites were 2 to 3 times smaller and areas were smaller by an order of magnitude.

  15. AFM topographies of densely packed nanoparticles: a quick way to determine the lateral size distribution by autocorrelation function analysis

    NASA Astrophysics Data System (ADS)

    Fekete, L.; Kůsová, K.; Petrák, V.; Kratochvílová, I.

    2012-08-01

    The distribution of sizes is one of the basic characteristics of nanoparticles. Here, we propose a novel way to determine the lateral distribution of sizes from AFM topographies. Our algorithm is based on the autocorrelation function and can be applied both on topographies containing spatially separated and densely packed nanoparticles as well as on topographies of polycrystalline films. As no manual treatment is required, this algorithm can be easily automatable for batch processing. The algorithm works in principle with any kind of spatially mapped information (AFM current maps, optical microscope images, etc.), and as such has no size limitations. However, in the case of AFM topographies, the tip/sample convolution effects will be the factor limiting the smallest size to which the algorithm is applicable. Here, we demonstrate the usefulness of this algorithm on objects with sizes ranging between 20 nm and 1.5 μm.

  16. Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki

    2016-10-01

    This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

  17. Pulsed Laser Ablation-Induced Green Synthesis of TiO2 Nanoparticles and Application of Novel Small Angle X-Ray Scattering Technique for Nanoparticle Size and Size Distribution Analysis.

    PubMed

    Singh, Amandeep; Vihinen, Jorma; Frankberg, Erkka; Hyvärinen, Leo; Honkanen, Mari; Levänen, Erkki

    2016-12-01

    This paper aims to introduce small angle X-ray scattering (SAXS) as a promising technique for measuring size and size distribution of TiO2 nanoparticles. In this manuscript, pulsed laser ablation in liquids (PLAL) has been demonstrated as a quick and simple technique for synthesizing TiO2 nanoparticles directly into deionized water as a suspension from titanium targets. Spherical TiO2 nanoparticles with diameters in the range 4-35 nm were observed with transmission electron microscopy (TEM). X-ray diffraction (XRD) showed highly crystalline nanoparticles that comprised of two main photoactive phases of TiO2: anatase and rutile. However, presence of minor amounts of brookite was also reported. The traditional methods for nanoparticle size and size distribution analysis such as electron microscopy-based methods are time-consuming. In this study, we have proposed and validated SAXS as a promising method for characterization of laser-ablated TiO2 nanoparticles for their size and size distribution by comparing SAXS- and TEM-measured nanoparticle size and size distribution. SAXS- and TEM-measured size distributions closely followed each other for each sample, and size distributions in both showed maxima at the same nanoparticle size. The SAXS-measured nanoparticle diameters were slightly larger than the respective diameters measured by TEM. This was because SAXS measures an agglomerate consisting of several particles as one big particle which slightly increased the mean diameter. TEM- and SAXS-measured mean diameters when plotted together showed similar trend in the variation in the size as the laser power was changed which along with extremely similar size distributions for TEM and SAXS validated the application of SAXS for size distribution measurement of the synthesized TiO2 nanoparticles.

  18. Sedimentologic Assessment of a Makran Tsunami Depsoit in Sur Lagoon Using High- Resolution Particle Size Distributions (PSDs) and Cluster Analysis

    NASA Astrophysics Data System (ADS)

    Reinhardt, E. G.; Donato, S. V.; Boyce, J. I.; Pilarczyk, J. E.

    2008-12-01

    The Makran subduction zone, which conveys the Arabian plate beneath Eurasia, has a poorly understood potential to generate tsunamis that would strike Oman, Iran, Pakistan, and India. The 1945 Makran earthquake (M 8.1), which resulted from a rupture 100-150 km long, caused a tsunami that reached heights of 5-15 m and killed an estimated 3,000 people on the coast of what is now Pakistan. The possibility of a full- length Makran rupture, approx. 750 km long, remains untested. The arid coastlines of the northern Arabian Sea (including parts of Oman, Iran, Pakistan and India) have had little attention regarding paleo-tsunami research. They lack the main environments where tsumani deposits have been found on temperate shores: tidal marshes, peatlands, and coastal lakes. Instead they offer sandy lagoons and salt flats where tsunami-laid sand sheets can be removed by wind, confused with the deposits of wadi sheet floods, and obliterated by burrowing crabs. Recent research has shown that a shell bed in Oman, likely from the 1945 tsunami (Sur Lagoon - Donato et al., 2008), contained distinctive molluscan assemblages and taphonomy, showing promise as a tsunami indicator for these arid settings. However, the large size of the molluscs is problematic in cores with small sample sizes, as the taphonomic data might not be representative enough to determine a tsunami origin without the use of additional proxies. Further characterization of the shell bed in Oman utilized high-resolution (cm scale) PSDs and Q-mode cluster analysis to identify the tsunami bed in cores (n=8). Results showed that the shell bed was more poorly sorted, and heterogeneous than the background lagoonal sediments. The tsunami bed thickness correlated generally with the thickness of the shell-bed, however cluster analysis of the particle size distributions (PSDs) extended the unit several centimeters above or below the shell-bed in some cores. The use of the full PSD (94 size classes) better characterized the

  19. Potential of ultrafiltration for organic matter removal in the polymer industry effluent based on particle size distribution analysis.

    PubMed

    Doğruel, Serdar; Çokgör, Emine Ubay; Ince, Orhan; Sözen, Seval; Orhon, Derin

    2013-01-01

    The purpose of the study was the experimental evaluation of ultrafiltration as a potential innovative technology for the removal of organic matter of around 15,000 mg chemical oxygen demand (COD) per liter in the polymer industry wastewater. Particle size distribution (PSD) analysis served as the major experimental instrument along with conventional chemical settling. Biodegradation characteristics of the remaining COD after ultrafiltration were determined by model interpretation of the corresponding oxygen uptake rate (OUR) profile. The study first involved a detailed characterization of the polymer wastewater including PSD analysis of the COD content. Chemical treatability was investigated using lime alone and with ferric chloride as coagulants followed with a PSD assessment of the chemically settled effluent. Modeling of the OUR profile generated by the ultrafiltration effluent defined related biodegradation kinetics and provided information on the overall COD removal potential. PSD analysis indicated that more than 70 % of the total COD accumulated in the 220- to 450-nm size range. It indicated that ultrafiltration was potentially capable of removing more than 90 % of the COD with an effluent lower than 1,500 mg COD/L. Chemical settling with 750 mg/L of FeCl(3) dosing at a pH of 7.0 provided a similar performance. The ultrafiltration effluent included mainly hydrolysable COD and proved to be biodegradable, with the process kinetics compatible with domestic sewage. PSD evaluation proved to be a valuable scientific instrument for underlining the merit of ultrafiltration as the appropriate innovative technology for polymer wastewater, removing the major portion of the COD in a way that is suitable for recovery and reuse and producing a totally biodegradable effluent.

  20. Permeability-Selectivity Analysis of Microfiltration and Ultrafiltration Membranes: Effect of Pore Size and Shape Distribution and Membrane Stretching

    PubMed Central

    Siddiqui, Muhammad Usama; Arif, Abul Fazal Muhammad; Bashmal, Salem

    2016-01-01

    We present a modeling approach to determine the permeability-selectivity tradeoff for microfiltration and ultrafiltration membranes with a distribution of pore sizes and pore shapes. Using the formulated permeability-selectivity model, the effect of pore aspect ratio and pore size distribution on the permeability-selectivity tradeoff of the membrane is analyzed. A finite element model is developed to study the effect of membrane stretching on the distribution of pore sizes and shapes in the stretched membrane. The effect of membrane stretching on the permeability-selectivity tradeoff of membranes is also analyzed. The results show that increasing pore aspect ratio improves membrane performance while increasing the width of pore size distribution deteriorates the performance. It was also found that the effect of membrane stretching on the permeability-selectivity tradeoff is greatly affected by the uniformity of pore distribution in the membrane. Stretching showed a positive shift in the permeability-selectivity tradeoff curve of membranes with well-dispersed pores while in the case of pore clustering, a negative shift in the permeability-selectivity tradeoff curve was observed. PMID:27509528

  1. Permeability-Selectivity Analysis of Microfiltration and Ultrafiltration Membranes: Effect of Pore Size and Shape Distribution and Membrane Stretching.

    PubMed

    Siddiqui, Muhammad Usama; Arif, Abul Fazal Muhammad; Bashmal, Salem

    2016-08-06

    We present a modeling approach to determine the permeability-selectivity tradeoff for microfiltration and ultrafiltration membranes with a distribution of pore sizes and pore shapes. Using the formulated permeability-selectivity model, the effect of pore aspect ratio and pore size distribution on the permeability-selectivity tradeoff of the membrane is analyzed. A finite element model is developed to study the effect of membrane stretching on the distribution of pore sizes and shapes in the stretched membrane. The effect of membrane stretching on the permeability-selectivity tradeoff of membranes is also analyzed. The results show that increasing pore aspect ratio improves membrane performance while increasing the width of pore size distribution deteriorates the performance. It was also found that the effect of membrane stretching on the permeability-selectivity tradeoff is greatly affected by the uniformity of pore distribution in the membrane. Stretching showed a positive shift in the permeability-selectivity tradeoff curve of membranes with well-dispersed pores while in the case of pore clustering, a negative shift in the permeability-selectivity tradeoff curve was observed.

  2. Analysis of phytoplankton distribution and community structure in the German Bight with respect to the different size classes

    NASA Astrophysics Data System (ADS)

    Wollschläger, Jochen; Wiltshire, Karen Helen; Petersen, Wilhelm; Metfies, Katja

    2015-05-01

    Investigation of phytoplankton biodiversity, ecology, and biogeography is crucial for understanding marine ecosystems. Research is often carried out on the basis of microscopic observations, but due to the limitations of this approach regarding detection and identification of picophytoplankton (0.2-2 μm) and nanophytoplankton (2-20 μm), these investigations are mainly focused on the microphytoplankton (20-200 μm). In the last decades, various methods based on optical and molecular biological approaches have evolved which enable a more rapid and convenient analysis of phytoplankton samples and a more detailed assessment of small phytoplankton. In this study, a selection of these methods (in situ fluorescence, flow cytometry, genetic fingerprinting, and DNA microarray) was placed in complement to light microscopy and HPLC-based pigment analysis to investigate both biomass distribution and community structure of phytoplankton. As far as possible, the size classes were analyzed separately. Investigations were carried out on six cruises in the German Bight in 2010 and 2011 to analyze both spatial and seasonal variability. Microphytoplankton was identified as the major contributor to biomass in all seasons, followed by the nanophytoplankton. Generally, biomass distribution was patchy, but the overall contribution of small phytoplankton was higher in offshore areas and also in areas exhibiting higher turbidity. Regarding temporal development of the community, differences between the small phytoplankton community and the microphytoplankton were found. The latter exhibited a seasonal pattern regarding number of taxa present, alpha- and beta-diversity, and community structure, while for the nano- and especially the picophytoplankton, a general shift in the community between both years was observable without seasonality. Although the reason for this shift remains unclear, the results imply a different response of large and small phytoplankton to environmental influences.

  3. A branching process model for the analysis of abortive colony size distributions in carbon ion-irradiated normal human fibroblasts.

    PubMed

    Sakashita, Tetsuya; Hamada, Nobuyuki; Kawaguchi, Isao; Hara, Takamitsu; Kobayashi, Yasuhiko; Saito, Kimiaki

    2014-05-01

    A single cell can form a colony, and ionizing irradiation has long been known to reduce such a cellular clonogenic potential. Analysis of abortive colonies unable to continue to grow should provide important information on the reproductive cell death (RCD) following irradiation. Our previous analysis with a branching process model showed that the RCD in normal human fibroblasts can persist over 16 generations following irradiation with low linear energy transfer (LET) γ-rays. Here we further set out to evaluate the RCD persistency in abortive colonies arising from normal human fibroblasts exposed to high-LET carbon ions (18.3 MeV/u, 108 keV/µm). We found that the abortive colony size distribution determined by biological experiments follows a linear relationship on the log-log plot, and that the Monte Carlo simulation using the RCD probability estimated from such a linear relationship well simulates the experimentally determined surviving fraction and the relative biological effectiveness (RBE). We identified the short-term phase and long-term phase for the persistent RCD following carbon-ion irradiation, which were similar to those previously identified following γ-irradiation. Taken together, our results suggest that subsequent secondary or tertiary colony formation would be invaluable for understanding the long-lasting RCD. All together, our framework for analysis with a branching process model and a colony formation assay is applicable to determination of cellular responses to low- and high-LET radiation, and suggests that the long-lasting RCD is a pivotal determinant of the surviving fraction and the RBE.

  4. A branching process model for the analysis of abortive colony size distributions in carbon ion-irradiated normal human fibroblasts

    PubMed Central

    Sakashita, Tetsuya; Hamada, Nobuyuki; Kawaguchi, Isao; Hara, Takamitsu; Kobayashi, Yasuhiko; Saito, Kimiaki

    2014-01-01

    A single cell can form a colony, and ionizing irradiation has long been known to reduce such a cellular clonogenic potential. Analysis of abortive colonies unable to continue to grow should provide important information on the reproductive cell death (RCD) following irradiation. Our previous analysis with a branching process model showed that the RCD in normal human fibroblasts can persist over 16 generations following irradiation with low linear energy transfer (LET) γ-rays. Here we further set out to evaluate the RCD persistency in abortive colonies arising from normal human fibroblasts exposed to high-LET carbon ions (18.3 MeV/u, 108 keV/µm). We found that the abortive colony size distribution determined by biological experiments follows a linear relationship on the log–log plot, and that the Monte Carlo simulation using the RCD probability estimated from such a linear relationship well simulates the experimentally determined surviving fraction and the relative biological effectiveness (RBE). We identified the short-term phase and long-term phase for the persistent RCD following carbon-ion irradiation, which were similar to those previously identified following γ-irradiation. Taken together, our results suggest that subsequent secondary or tertiary colony formation would be invaluable for understanding the long-lasting RCD. All together, our framework for analysis with a branching process model and a colony formation assay is applicable to determination of cellular responses to low- and high-LET radiation, and suggests that the long-lasting RCD is a pivotal determinant of the surviving fraction and the RBE. PMID:24501383

  5. Flare Size Distributions and Active Region Types

    NASA Astrophysics Data System (ADS)

    Bai, Taeil

    2007-05-01

    Size distributions of solar flares measured by various size indicators follow a power law with a negative index of about 1.8. On the basis of general appearance of power-law distributions, Lu and his collegues proposed an avalenche model. According to this model, the power-law index should be independent of active region size, but the cutoff size above which the size distribution steepens rapidly is expected to depend on the active region size. I have analyzed the size distribution of flares, using GOES soft X-ray observations for 2004 and 2005. For flares observed by GOES during these years, their locations are almost completely identified even for C-class flares. This enable us to study the dependence of size distribution on active region type. Comparing the power-law portion of size distributions below the high-end cutoff, I have found that the size distribution index depends on active region type. Flares from prolific active regions exhibit a flatter distribution, while flares from non-prolific active regions exhibit a steeper distribution. I plan to discuss a plausible mechanism for such behavior.

  6. Remote Laser Diffraction Particle Size Distribution Analyzer

    SciTech Connect

    Batcheller, Thomas Aquinas; Huestis, Gary Michael; Bolton, Steven Michael

    2001-03-01

    In support of a radioactive slurry sampling and physical characterization task, an “off-the-shelf” laser diffraction (classical light scattering) particle size analyzer was utilized for remote particle size distribution (PSD) analysis. Spent nuclear fuel was previously reprocessed at the Idaho Nuclear Technology and Engineering Center (INTEC—formerly recognized as the Idaho Chemical Processing Plant) which is on DOE’s INEEL site. The acidic, radioactive aqueous raffinate streams from these processes were transferred to 300,000 gallon stainless steel storage vessels located in the INTEC Tank Farm area. Due to the transfer piping configuration in these vessels, complete removal of the liquid can not be achieved. Consequently, a “heel” slurry remains at the bottom of an “emptied” vessel. Particle size distribution characterization of the settled solids in this remaining heel slurry, as well as suspended solids in the tank liquid, is the goal of this remote PSD analyzer task. A Horiba Instruments Inc. Model LA-300 PSD analyzer, which has a 0.1 to 600 micron measurement range, was modified for remote application in a “hot cell” (gamma radiation) environment. This technology provides rapid and simple PSD analysis, especially down in the fine and microscopic particle size regime. Particle size analysis of these radioactive slurries down in this smaller range was not previously achievable—making this technology far superior than the traditional methods used. Successful acquisition of this data, in conjunction with other characterization analyses, provides important information that can be used in the myriad of potential radioactive waste management alternatives.

  7. Particle Size Analysis.

    ERIC Educational Resources Information Center

    Barth, Howard G.; Sun, Shao-Tang

    1989-01-01

    Presents a review of research focusing on scattering, elution techniques, electrozone sensing, filtration, centrifugation, comparison of techniques, data analysis, and particle size standards. The review covers the period 1986-1988. (MVL)

  8. Particle Size Analysis.

    ERIC Educational Resources Information Center

    Barth, Howard G.; Sun, Shao-Tang

    1989-01-01

    Presents a review of research focusing on scattering, elution techniques, electrozone sensing, filtration, centrifugation, comparison of techniques, data analysis, and particle size standards. The review covers the period 1986-1988. (MVL)

  9. Variations of sediment size and size distribution along a river

    NASA Astrophysics Data System (ADS)

    Jan, C. D.; Tsai, Y. C.; Yang, S. Y.

    2015-12-01

    Sediment material of a river bed is an important factor for river morphodynamics. Typically, alluvial rivers construct their own geometries based on the sediment size and its distribution that affect the sediment transport capacity in river channel networks, involving the issues of watershed sediment yield, flood controls and the evolution of flood plain, habitats, deltas and adjacent coastline. Hence, investigating grain size and size distribution of sediment materials on riverbeds is important for practical river management and assessment of landscape evolution. In this study, we collected total 43 sediment samplings along the Koaping River in southern Taiwan to analyze the grain size and its distribution along the river. Spatial distributions of different representative grain sizes, such as D50 and D90, and the size corresponding Manning's n values are analyzed and discussed in this paper. An exponential grain size distribution (GSD) formula is used to explore the relation between the frequency and size of riverbed sediment. Results show that the grain size has a wide range distribution in the river upstream but displays a narrow-range variation in the river downstream. For example, the sediment medium size D50 ranges from 1.25 mm to 391.27 mm with an average of 49.36 mm in the upstream while it ranges from 0.135 mm to 0.625 mm with an average of 0.338 mm in the downstream. The best fitting curves of GSD with exponential scaling are analyzed with an empirical parameter Dc that is used to normalize the sediment grain size. This study finds that the empirical parameter Dc could be replaced by the sediment resentative size D65 (65% of sediment smaller than it). The results obtained herein could be useful not only in analyzing sediment transport of a river but also in river management.

  10. KNIFE MILL COMMINUTION ENERGY ANALYSIS OF SWITCHGRASS, WHEAT STRAW, AND CORN STOVER AND CHARACTERIZATION OF PARTICLE SIZE DISTRIBUTIONS

    SciTech Connect

    Bitra, V.S.P.; Womac, A.R.; Sokhansanj, Shahabaddine; Igathinathane, C.

    2010-01-01

    Biomass preprocessing and pretreatment technologies such as size reduction and chemical preconditioning are aimed at reducing the cost of ethanol production from lignocellulosic biomass. Size reduction is an energy-intensive biomass preprocessing unit operation. In this study, switchgrass, wheat straw, and corn stover were chopped in an instrumented knife mill to evaluate size reduction energy and corresponding particle size distribution as determined with a standard forage sieve analyzer. Direct mechanical power inputs were determined using a dedicated data acquisition system for knife mill screen openings from 12.7 to 50.8 mm, rotor speeds between 250 and 500 rpm, and mass feed rates from 1 to 11 kg/min. A speed of 250 rpm gave optimum performance of the mill. Optimum feed rates for 25.4 mm screen and 250 rpm were 7.6, 5.8, and 4.5 kg/min for switchgrass, wheat straw, and corn stover, respectively. Total specific energy (MJ/Mg) was defined as the size reduction energy required to operate the knife mill plus that imparted to the biomass. Effective specific energy was defined as the energy imparted to the biomass. For these conditions, total specific energies were 27.3, 37.9, and 31.9 MJ/Mg and effective specific energies were 10.1, 15.5, and 3.2 MJ/Mg for switchgrass, wheat straw, and corn stover, respectively. These results demonstrated that biomass selection affects the size reduction energy, even for biomass with similar features. Second-order polynomial equations for the total specific energy requirement fitted well (R2 > 0.95) as a function of knife mill screen size, mass feed rate, and speed for biomass materials tested. The Rosin-Rammler equation fitted the cumulative undersize mass of switchgrass, wheat straw, and corn stover chop passed through ASABE sieves with high R2 (>0.983). Knife mill chopping of switchgrass, wheat straw, and corn stover resulted in particle size distributions classified as 'well-graded strongly fine-skewed mesokurtic', 'well

  11. How does biomass distribution change with size and differ among species? An analysis for 1200 plant species from five continents.

    PubMed

    Poorter, Hendrik; Jagodzinski, Andrzej M; Ruiz-Peinado, Ricardo; Kuyah, Shem; Luo, Yunjian; Oleksyn, Jacek; Usoltsev, Vladimir A; Buckley, Thomas N; Reich, Peter B; Sack, Lawren

    2015-11-01

    We compiled a global database for leaf, stem and root biomass representing c. 11 000 records for c. 1200 herbaceous and woody species grown under either controlled or field conditions. We used this data set to analyse allometric relationships and fractional biomass distribution to leaves, stems and roots. We tested whether allometric scaling exponents are generally constant across plant sizes as predicted by metabolic scaling theory, or whether instead they change dynamically with plant size. We also quantified interspecific variation in biomass distribution among plant families and functional groups. Across all species combined, leaf vs stem and leaf vs root scaling exponents decreased from c. 1.00 for small plants to c. 0.60 for the largest trees considered. Evergreens had substantially higher leaf mass fractions (LMFs) than deciduous species, whereas graminoids maintained higher root mass fractions (RMFs) than eudicotyledonous herbs. These patterns do not support the hypothesis of fixed allometric exponents. Rather, continuous shifts in allometric exponents with plant size during ontogeny and evolution are the norm. Across seed plants, variation in biomass distribution among species is related more to function than phylogeny. We propose that the higher LMF of evergreens at least partly compensates for their relatively low leaf area : leaf mass ratio.

  12. [The fractal characteristics of particle size distribution and conservation relationship].

    PubMed

    Jin, Peng-kang; Wang, Xiao-chang

    2004-01-01

    Using a microscopic technique, the characteristics of particle size distribution of Al-humic flocs were studied. The results showed that Al-humic floc size followed a lognormal distribution. By introducing the lognormal distribution and fractal dimension into the fundamental kinetic equation of flocculation, a conservation relationship was obtained between the total number of particles, average floc volume and standard deviation of floc size distribution. Significance of the relation can greatly simplify the complicated procedure of kinetic analysis and enable a more accurate evaluation of floc size distribution.

  13. Body size distribution of the dinosaurs.

    PubMed

    O'Gorman, Eoin J; Hone, David W E

    2012-01-01

    The distribution of species body size is critically important for determining resource use within a group or clade. It is widely known that non-avian dinosaurs were the largest creatures to roam the Earth. There is, however, little understanding of how maximum species body size was distributed among the dinosaurs. Do they share a similar distribution to modern day vertebrate groups in spite of their large size, or did they exhibit fundamentally different distributions due to unique evolutionary pressures and adaptations? Here, we address this question by comparing the distribution of maximum species body size for dinosaurs to an extensive set of extant and extinct vertebrate groups. We also examine the body size distribution of dinosaurs by various sub-groups, time periods and formations. We find that dinosaurs exhibit a strong skew towards larger species, in direct contrast to modern day vertebrates. This pattern is not solely an artefact of bias in the fossil record, as demonstrated by contrasting distributions in two major extinct groups and supports the hypothesis that dinosaurs exhibited a fundamentally different life history strategy to other terrestrial vertebrates. A disparity in the size distribution of the herbivorous Ornithischia and Sauropodomorpha and the largely carnivorous Theropoda suggests that this pattern may have been a product of a divergence in evolutionary strategies: herbivorous dinosaurs rapidly evolved large size to escape predation by carnivores and maximise digestive efficiency; carnivores had sufficient resources among juvenile dinosaurs and non-dinosaurian prey to achieve optimal success at smaller body size.

  14. Body Size Distribution of the Dinosaurs

    PubMed Central

    O’Gorman, Eoin J.; Hone, David W. E.

    2012-01-01

    The distribution of species body size is critically important for determining resource use within a group or clade. It is widely known that non-avian dinosaurs were the largest creatures to roam the Earth. There is, however, little understanding of how maximum species body size was distributed among the dinosaurs. Do they share a similar distribution to modern day vertebrate groups in spite of their large size, or did they exhibit fundamentally different distributions due to unique evolutionary pressures and adaptations? Here, we address this question by comparing the distribution of maximum species body size for dinosaurs to an extensive set of extant and extinct vertebrate groups. We also examine the body size distribution of dinosaurs by various sub-groups, time periods and formations. We find that dinosaurs exhibit a strong skew towards larger species, in direct contrast to modern day vertebrates. This pattern is not solely an artefact of bias in the fossil record, as demonstrated by contrasting distributions in two major extinct groups and supports the hypothesis that dinosaurs exhibited a fundamentally different life history strategy to other terrestrial vertebrates. A disparity in the size distribution of the herbivorous Ornithischia and Sauropodomorpha and the largely carnivorous Theropoda suggests that this pattern may have been a product of a divergence in evolutionary strategies: herbivorous dinosaurs rapidly evolved large size to escape predation by carnivores and maximise digestive efficiency; carnivores had sufficient resources among juvenile dinosaurs and non-dinosaurian prey to achieve optimal success at smaller body size. PMID:23284818

  15. Scaling in animal group-size distributions

    PubMed Central

    Bonabeau, Eric; Dagorn, Laurent; Fréon, Pierre

    1999-01-01

    An elementary model of animal aggregation is presented. The group-size distributions resulting from this model are truncated power laws. The predictions of the model are found to be consistent with data that describe the group-size distributions of tuna fish, sardinellas, and African buffaloes. PMID:10200286

  16. City size distributions and spatial economic change.

    PubMed

    Sheppard, E

    1982-10-01

    "The concept of the city size distribution is criticized for its lack of consideration of the effects of interurban interdependencies on the growth of cities. Theoretical justifications for the rank-size relationship have the same shortcomings, and an empirical study reveals that there is little correlation between deviations from rank-size distributions and national economic and social characteristics. Thus arguments suggesting a close correspondence between city size distributions and the level of development of a country, irrespective of intranational variations in city location and socioeconomic characteristics, seem to have little foundation." (summary in FRE, ITA, JPN, ) excerpt

  17. An analysis of the growth based on the size and age distributions of the hawksbill sea turtle inhabiting Cuban waters.

    PubMed

    Kobayashi, M

    2000-11-01

    The first costal scute (C 1) collected from 2, 749 hawksbill turtle (Eretmochelys imbricata) captured in Cuban waters in 1993 and 1994 were analyzed to determine their body size and age distributions. The C 1 width (C 1 W) was converted to the straight carapace length (SCL) using a formula, SCL = 4.3527 (C 1 W)0.8484, to examine its body size distribution. The SCL ranged from 51.3 to 96.1 cm with 68.8 cm of mean and 68.6 cm of median. Ages of captured turtles estimated from the C 1 surface patterns were ranged from 3.3 to 61.5 years old with 15.8 years of mean and 14.5 years of median. A growth function of van Bertalanffy, M(t) = A(1-Be-kt), was applied to determine the relationship between the age and body size (SCL). A formula, SCL = 80.4(1 -0.663e-0.118(Age)), was derived and indicated a slowdown in the growth after about 14 years old. The maturation age and the rate of sexually matured Cuban hawksbill turtles were also discussed based on these results.

  18. Evaluation of droplet size distributions using univariate and multivariate approaches.

    PubMed

    Gaunø, Mette Høg; Larsen, Crilles Casper; Vilhelmsen, Thomas; Møller-Sonnergaard, Jørn; Wittendorff, Jørgen; Rantanen, Jukka

    2013-01-01

    Pharmaceutically relevant material characteristics are often analyzed based on univariate descriptors instead of utilizing the whole information available in the full distribution. One example is droplet size distribution, which is often described by the median droplet size and the width of the distribution. The current study was aiming to compare univariate and multivariate approach in evaluating droplet size distributions. As a model system, the atomization of a coating solution from a two-fluid nozzle was investigated. The effect of three process parameters (concentration of ethyl cellulose in ethanol, atomizing air pressure, and flow rate of coating solution) on the droplet size and droplet size distribution using a full mixed factorial design was used. The droplet size produced by a two-fluid nozzle was measured by laser diffraction and reported as volume based size distribution. Investigation of loading and score plots from principal component analysis (PCA) revealed additional information on the droplet size distributions and it was possible to identify univariate statistics (volume median droplet size), which were similar, however, originating from varying droplet size distributions. The multivariate data analysis was proven to be an efficient tool for evaluating the full information contained in a distribution.

  19. Particles size distribution in diluted magnetic fluids

    NASA Astrophysics Data System (ADS)

    Yerin, Constantine V.

    2017-06-01

    Changes in particles and aggregates size distribution in diluted kerosene based magnetic fluids is studied by dynamic light scattering method. It has been found that immediately after dilution in magnetic fluids the system of aggregates with sizes ranging from 100 to 250-1000 nm is formed. In 50-100 h after dilution large aggregates are peptized and in the sample stationary particles and aggregates size distribution is fixed.

  20. Size distributions of solar energetic particle events

    NASA Technical Reports Server (NTRS)

    Cliver, E.; Reames, D.; Kahler, S.; Cane, H.

    1991-01-01

    NASA particle detectors on the IMP-8 are employed to determine the size distributions of the peak fluxes of events related to solar-energetic particles including protons and electrons. The energetic proton events show a flatter size distribution which suggests that not all flares are proton flares. Both the electron and proton events are classified as either 'impulsive' or 'gradual', and the impulsive events tend to have a steeper power-law distribution.

  1. Experimental determination of size distributions: analyzing proper sample sizes

    NASA Astrophysics Data System (ADS)

    Buffo, A.; Alopaeus, V.

    2016-04-01

    The measurement of various particle size distributions is a crucial aspect for many applications in the process industry. Size distribution is often related to the final product quality, as in crystallization or polymerization. In other cases it is related to the correct evaluation of heat and mass transfer, as well as reaction rates, depending on the interfacial area between the different phases or to the assessment of yield stresses of polycrystalline metals/alloys samples. The experimental determination of such distributions often involves laborious sampling procedures and the statistical significance of the outcome is rarely investigated. In this work, we propose a novel rigorous tool, based on inferential statistics, to determine the number of samples needed to obtain reliable measurements of size distribution, according to specific requirements defined a priori. Such methodology can be adopted regardless of the measurement technique used.

  2. First analysis of the size-frequency distribution of boulders ge 7m on comet 67P

    NASA Astrophysics Data System (ADS)

    Pajola, M.; Vincent, J. B.; Güttler, C.; Lee, J.-C.; Massironi, M.; Bertini, I.; Simioni, E.; Marzari, F.; Giacomini, L.; Barbieri, C.; Cremonese, G.; Naletto, G.; Pommerol, A.; El Maarry, M. R.; Besse, S.; Küppers, M.; La Forgia, F.; Lazzarin, M.; Thomas, N.; Auger, A. T.; Ip, W.-H.; Lin, Z.-Y.; Sierks, H.; OSIRIS Team; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Da Deppo, V.; Davidsson, B.; De Cecco, M.; Debei, S.; Ferri, F.; Fornasier, S.; Fulle, M.; Groussin, O.; Gutierrez, P. J.; Hviid, S. F.; Jorda, L.; Keller, H. U.; Knollenberg, J.; Koschny, D.; Kramm, J.-R.; Kürt, E.; Lamy, P.; Lara, L. M.; Lopez Moreno, J. J.; Magrin, S.; Michalik, H.; Moissl, R.; Mottola, S.; Oklay, N.; Preusker, F.; Rickman, H.; Rodrigo, R.; Scholten, F.; Tubiana, C.

    Images of the surface of comet 67P Churyumov-Gerasimenko taken by the OSIRIS camera on board the Rosetta spacecraft have been used to study the statistical distribution and morphological properties of both cluster and isolated roundish structures ('boulders') scattered all over the surface. We used NAC images taken on Aug 5-6, 2014, at a distance between 131.45 - 109.76 km, with a spatial resolution ranging from 2.44 - 2.03 m/px (Fig. 1). Such data cover a full rotation of 67P, providing the first ever full size frequency distribution coverage of boulders ≥ 7m visible on a cometary illuminated side. Boulders are ubiquitous on the head, neck, and body of 67P \\citep{thomas15}. The initial count of 4,976 boulders was reduced to 3,546 for statistical purposes taking into consideration only those with a diameter larger than 7 m \\citep{pajola15}.

  3. Asteroid Size-Frequency Distribution

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    2001-01-01

    A total of six deep exposures (using AOT CAM01 with a 6 inch PFOV) through the ISOCAM LW10 filter (IRAS Band 1, i.e. 12 micron) were obtained on an approximately 15 arcminute square field centered on the ecliptic plane. Point sources were extracted using the technique described. Two known asteroids appear in these frames and 20 sources moving with velocities appropriate for main belt asteroids are present. Most of the asteroids detected have flux densities less than 1 mJy, i,e., between 150 and 350 times fainter than any of the asteroids observed by IRAS. These data provide the first direct measurement of the 12 pm sky-plane density for asteroids on the ecliptic equator. The median zodiacal foreground, as measured by ISOCAM during this survey, is found to be 22.1 +/- 1.5 mJy per pixel, i.e., 26.2 +/- 1.7 MJy/sr. The results presented here imply that the actual number of kilometer-sized asteroids is significantly greater than previously believed and in reasonable agreement with the Statistical Asteroid Model.

  4. Analysis of the adequate size of a cord blood bank and comparison of HLA haplotype distributions between four populations.

    PubMed

    Haimila, Katri; Penttilä, Antti; Arvola, Anne; Auvinen, Marja-Kaisa; Korhonen, Matti

    2013-02-01

    The number of units and especially the number of different HLA haplotypes present in a cord blood (CB) bank is a crucial determinant of its usefulness. We generated data relevant to the development of our national CB in Finland. The HLA haplotype distribution was examined between specific populations. We developed graphical ways of data presentation that enable easy visualization of differences. First, we estimated the optimal size of a CB bank for Finland and found that approximately 1700 units are needed to provide a 5/6 HLA-matched donor for 80% of Finnish patients. Secondly, we evaluated HLA haplotype distributions between four locations, Finland, Japan, Sweden and Belgium. Our results showed that the Japanese Tokyo Cord Blood Bank differs in both the frequency and distribution of haplotypes from the European banks. The European banks (Finnish Cord Blood Registry, The Swedish National Cord Blood Bank, and Marrow Donor Program-Belgium) have similar frequencies of common haplotypes, but 26% of the haplotypes in the Finnish CB bank are unique, which justifies the existence of a national bank. The tendency to a homogenous HLA haplotype distribution in banks underlines the need for targeting recruitment at the poorly represented minority populations.

  5. Electronic cigarette aerosol particle size distribution measurements.

    PubMed

    Ingebrethsen, Bradley J; Cole, Stephen K; Alderman, Steven L

    2012-12-01

    The particle size distribution of aerosols produced by electronic cigarettes was measured in an undiluted state by a spectral transmission procedure and after high dilution with an electrical mobility analyzer. The undiluted e-cigarette aerosols were found to have particle diameters of average mass in the 250-450 nm range and particle number concentrations in the 10(9) particles/cm(3) range. These measurements are comparable to those observed for tobacco burning cigarette smoke in prior studies and also measured in the current study with the spectral transmission method and with the electrical mobility procedure. Total particulate mass for the e-cigarettes calculated from the size distribution parameters measured by spectral transmission were in good agreement with replicate determinations of total particulate mass by gravimetric filter collection. In contrast, average particle diameters determined for e-cigarettes by the electrical mobility method are in the 50 nm range and total particulate masses calculated based on the suggested diameters are orders of magnitude smaller than those determined gravimetrically. This latter discrepancy, and the very small particle diameters observed, are believed to result from almost complete e-cigarette aerosol particle evaporation at the dilution levels and conditions of the electrical mobility analysis. A much smaller degree, ~20% by mass, of apparent particle evaporation was observed for tobacco burning cigarette smoke. The spectral transmission method is validated in the current study against measurements on tobacco burning cigarette smoke, which has been well characterized in prior studies, and is supported as yielding an accurate characterization of the e-cigarette aerosol particle size distribution.

  6. Measurement of nonvolatile particle number size distribution

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G. I.; Papanastasiou, D. K.; Florou, K.; Kaltsonoudis, C.; Louvaris, E.; Pandis, S. N.

    2016-01-01

    An experimental methodology was developed to measure the nonvolatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a nonvolatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol (OA; 40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50-60 % of the particles had a nonvolatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon with an 80 % contribution, while OA was responsible for another 15-20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type of OA

  7. Landslide size distribution in seismic areas

    NASA Astrophysics Data System (ADS)

    Valagussa, Andrea; Frattini, Paolo; Crosta, Giovanni B.

    2015-04-01

    In seismic areas, the analysis of the landslides size distribution with the distance from the seismic source is very important for hazard zoning and land planning. From numerical modelling (Bourdeau et al., 2004), it has been observed that the area of the sliding mass tends to increase with the ground-motion amplitude up to a certain threshold input acceleration. This has been also observed empirically for the 1989 Loma Prieta earthquake (Keefer and Manson, 1998) and 1999 Chi Chi earthquake (Khazai and Sitar, 2003). Based on this, it possible to assume that the landslide size decreases with the increase of the distance from the seismic source. In this research, we analysed six earthquakes-induced landslides inventories (Papua New Guinea Earthquake, 1993; Northridge Earthquake, 1994; Niigata-Chuetsu Earthquake 2004; Iwate-Miyagi Nairiku Earthquake, 2008; Wenchuan Earthquake, 2008; Tohoku Earthquake, 2011) with a magnitude ranging between 6.6 and 9.0 Mw. For each earthquake, we first analysed the size of landslides as a function of different factors such as the lithology, the PGA, the relief, the distance from the seismic sources (both fault and epicentre). Then, we analysed the magnitude frequency curves for different distances from the source area and for each lithology. We found that a clear relationship between the size distribution and the distance from the seismic source is not evident, probably due to the combined effect of the different influencing factors and to the non-linear relationship between the ground-motion intensity and the distance from the seismic source.

  8. [The finite element analysis of stress distribution in different size of MO cavities restored with composite resin inlays].

    PubMed

    Zhang, Long; Lu, Yi; Yang, Bo-song; Guo, Yan; Li, Fang-ping

    2015-04-01

    To explore the effect of different depth and width of meiso-occlusal (Class II) cavity type on the tooth tissue resistance stress after restoration with composite resin inlays. The 3-D finite element model of mandibular first molar with meiso-occlusal (Class II) cavity restored with composite resin inlay was established by using CBCT scanning and reverse engineering software Mimics, Geomagic Studio, and finite element analysis software ANSYS. Comparative analysis of restoration with different depth and width meiso-occlusal (Class II) cavity under the same load of perpendicular and 45° deviation was explored, and finally the main stress and Von-mises stress changed as well as stress distribution were analyzed. The main stress was located in the gingival wall opposite to the inlay, while the major stress concentration area of the tooth was distributed near the canal at the bottom of the cavity. With the increase of the depth and width, the main stress and Von-mises stress distribution areas of tooth were getting larger. The Von-mises stress of tooth was influenced by the width variation of the cavity, while that depth change of cavity was affected by Von Mises stress of the inlay. With the increase of the depth and width of the cavity as well as lateral loading force, the peak stress of tooth with inlays increased and the distribution of stress concentration is modified after meiso-occlusal (Class II) cavity being inlayed with composite resin.

  9. Understanding Animal Group-Size Distributions

    PubMed Central

    Griesser, Michael; Ma, Qi; Webber, Simone; Bowgen, Katharine; Sumpter, David J. T.

    2011-01-01

    One of the most striking aspects of animal groups is their remarkable variation in size, both within and between species. While a number of mechanistic models have been proposed to explain this variation, there are few comprehensive datasets against which these models have been tested. In particular, we only vaguely understand how environmental factors and behavioral activities affect group-size distributions. Here we use observations of House sparrows (Passer domesticus) to investigate the factors determining group-size distribution. Over a wide range of conditions, we observed that animal group sizes followed a single parameter distribution known as the logarithmic distribution. This single parameter is the mean group size experienced by a randomly chosen individual (including the individual itself). For sparrows, the experienced mean group size, and hence the distribution, was affected by four factors: morning temperature, place, behavior and the degree of food spillage. Our results further indicate that the sparrows regulate the mean group size they experience, either by groups splitting more or merging less when local densities are high. We suggest that the mean experienced group size provides a simple but general tool for assessing the ecology and evolution of grouping. PMID:21912596

  10. Analytic modeling of aerosol size distributions

    NASA Technical Reports Server (NTRS)

    Deepack, A.; Box, G. P.

    1979-01-01

    Mathematical functions commonly used for representing aerosol size distributions are studied parametrically. Methods for obtaining best fit estimates of the parameters are described. A catalog of graphical plots depicting the parametric behavior of the functions is presented along with procedures for obtaining analytical representations of size distribution data by visual matching of the data with one of the plots. Examples of fitting the same data with equal accuracy by more than one analytic model are also given.

  11. Eruption of Deep Mushy Magma from the Searchlight Magma System, Southern Nevada (USA): a Crystal Size Distribution and Geochemical Analysis

    NASA Astrophysics Data System (ADS)

    Bazar, D.; Miller, J.; Miller, C.; Dodge, M.; Hodge, K.; Faulds, J.

    2006-12-01

    The Miocene Searchlight pluton and overlying volcanic rocks are exposed in the Eldorado Mountains of southern Nevada within the Colorado River Extensional Corridor. Steep tilting of the pluton and its cover provides an exceptional opportunity to study the magmatic plumbing system from bottom to top, including possible eruptions of magma from the Searchlight magma system. The pluton is approximately 10 km thick and divided into three compositionally distinct units that solidified in monotonic fashion: a 2 km thick upper fine-grained quartz monzonite (solidification front), a 6 km thick lower, more mafic quartz monzonite (cumulate), and a 2 km thick middle granite (extracted melt) [ref]. In addition, near E-W-striking rhyolite and trachydacite porphyry dikes intrude the upper quartz monzonite unit (but not the lower or middle units), and identical trachydacite porphyries (locally > 45 vol. % crystals) occur as irregular pods and masses in the roof area. The trachydacite porphyries superficially resemble trachydacite lavas in part of the overlying volcanic section. Ion probe zircon ages are identical within error for the upper unit, the lower unit, and the trachydacite dikes and pods (206Pb/238U age for samples of each ranging from 16.6±0.3 Ma to 16.9±0.2 Ma 2σ). Ages for the middle granite unit and rhyolite dikes are consistently younger (15.8-16.0 Ma). Crystal size distribution (CSD) analysis on plagioclase has been undertaken on samples from the upper Searchlight and overlying volcanic rocks in order to establish and corroborate linkages between the volcanic and intrusive units and to better understand the growth and solidification history of the Searchlight magma system. The CSD's for the intermediate porphyry dikes and pods that intrude upper Searchlight pluton are identical to trachydacite lava flows and domes erupted onto Proterozoic gneiss and earlier lava flows that comprise the roof of the pluton. The CSD's for these rocks are distinctly concave up and

  12. Rock size-frequency distributions analysis at lunar landing sites based on remote sensing and in-situ imagery

    NASA Astrophysics Data System (ADS)

    Li, Bo; Ling, Zongcheng; Zhang, Jiang; Chen, Jian

    2017-10-01

    Rock populations can supply fundamental geological information about origin and evolution of a planet. In this paper, we used Lunar Reconnaissance Orbiter (LRO) narrow-angle camera (NAC) images to identify rocks at the lunar landing sites (including Chang'e 3 (CE-3), Apollo and Surveyor series). The diameter and area of each identified rock were measured to generate distributions of rock cumulative fractional area and size-frequency on a log-log plot. The two distributions both represented the same shallow slopes at smaller diameters followed by steeper slopes at larger diameters. A reasonable explanation for the lower slopes may be the resolution and space weathering effects. By excluding the smaller diameters, rock populations derived from NAC images showed approximately linear relationships and could be fitted well by power laws. In the last, the entire rock populations derived from both NAC and in-situ imagery could be described by one power function at the lunar landing sites except the CE-3 and Apollo 11 landing sites. This may be because that the process of a large rock breaking down to small rocks even fine particles can be modeled by fractal theories. Thus, rock populations on lunar surfaces can be extrapolated along the curves of rock populations derived from NAC images to smaller diameters. In the future, we can apply rock populations from remote sensing images to estimate the number of rocks with smaller diameters to select the appropriate landing sites for the CE-4 and CE-5 missions.

  13. Is there a size limit for cosmopolitan distribution in free-living microorganisms? A biogeographical analysis of testate amoebae from polar areas.

    PubMed

    Yang, Jun; Smith, Humphrey G; Sherratt, Thomas N; Wilkinson, David M

    2010-05-01

    A long-standing debate in microbial ecology is the extent to which free-living microorganisms exhibit cosmopolitan distributions. We use a comparison of testate amoebae communities in cold "polar" locations (Arctic, Antarctic, and Tibet) to investigate how a microorganism's size affects its probability of having a cosmopolitan distribution. We show that the probability a given taxa being reported in all three locations increases as testate size decreases. Likewise, excluding those testates found only in Tibet, very small testates (<20 microm) are more likely to occur in both the Arctic and Antarctic than in either of these poles alone. Attempting to correct for phylogeny reduces the number of statistically significant relationships--both because of decreased sample size and potentially real phylogenetic patterns, although some size-dependent effects were still apparent. In particular, taxa found in both the Arctic and Antarctic poles were significantly smaller than congeneric taxa found only in Tibet. This pattern may in part be due to habitat effects, with the Tibetan samples being more likely to have come from aquatic sites which may be more suitable for larger taxa. Overall, our analysis suggests that, at least within testate amoebae, a cosmopolitan distribution becomes increasingly common as median taxon size decreases.

  14. Particle Size Distributions in Atmospheric Clouds

    NASA Technical Reports Server (NTRS)

    Paoli, Roberto; Shariff, Karim

    2003-01-01

    In this note, we derive a transport equation for a spatially integrated distribution function of particles size that is suitable for sparse particle systems, such as in atmospheric clouds. This is done by integrating a Boltzmann equation for a (local) distribution function over an arbitrary but finite volume. A methodology for evolving the moments of the integrated distribution is presented. These moments can be either tracked for a finite number of discrete populations ('clusters') or treated as continuum variables.

  15. Direct mechanical energy measures of hammer mill comminution of switchgrass, wheat straw, and corn stover and analysis of their particle size distributions

    SciTech Connect

    Bitra, V.S.P; Womac, A.R.; Chevanan, Nehru; Miu, P.I.; Smith, D.R.; Igathinathane, C.; Sokhansanj, Shahabaddine

    2009-07-01

    particles. Uniformity coefficient was < 4.0 for wheat straw, which indicated uniform mix of particles, and it was about 4.0 for switchgrass and corn stover, which indicated a moderate assortment of particles. Size-related parameters, namely, geometric mean diameter, Rosin Rammler size parameter, median diameter, and effective size had strong correlation among themselves and good negative correlation with speed. Distribution-related parameters, namely, Rosin Rammler distribution parameter, mass relative span, inclusive graphic skewness, graphic kurtosis, uniformity index, uniformity coefficient, coefficient of gradation and distribution geometric standard deviation had strong correlation among themselves and a weak correlation with mill speed. Results of this extensive analysis of specific energy and particle sizes can be applied to selection of hammer mill operating factors to produce a particular size of switchgrass, wheat straw, and corn stover grind, and will serve as a guide for relations among the energy and various analytic descriptors of biomass particle distributions.

  16. Knife mill operating factors effect on switchgrass particle size distributions.

    PubMed

    Bitra, Venkata S P; Womac, Alvin R; Yang, Yuechuan T; Igathinathane, C; Miu, Petre I; Chevanan, Nehru; Sokhansanj, Shahab

    2009-11-01

    Biomass particle size impacts handling, storage, conversion, and dust control systems. Switchgrass (Panicum virgatum L.) particle size distributions created by a knife mill were determined for integral classifying screen sizes from 12.7 to 50.8 mm, operating speeds from 250 to 500 rpm, and mass input rates from 2 to 11 kg/min. Particle distributions were classified with standardized sieves for forage analysis that included horizontal sieving motion with machined-aluminum sieves of thickness proportional to sieve opening dimensions. Then, a wide range of analytical descriptors were examined to mathematically represent the range of particle sizes in the distributions. Correlation coefficient of geometric mean length with knife mill screen size, feed rate, and speed were 0.872, 0.349, and 0.037, respectively. Hence, knife mill screen size largely determined particle size of switchgrass chop. Feed rate had an unexpected influence on particle size, though to a lesser degree than screen size. The Rosin-Rammler function fit the chopped switchgrass size distribution data with an R(2)>0.982. Mass relative span was greater than 1, which indicated a wide distribution of particle sizes. Uniformity coefficient was more than 4.0, which indicated a large assortment of particles and also represented a well-graded particle size distribution. Knife mill chopping of switchgrass produced 'strongly fine skewed mesokurtic' particles with 12.7-25.4 mm screens and 'fine skewed mesokurtic' particles with 50.8 mm screen. Results of this extensive analysis of particle sizes can be applied to selection of knife mill operating parameters to produce a particular size of switchgrass chop, and will serve as a guide for relations among the various analytic descriptors of biomass particle distributions.

  17. Knife mill operating factors effect on switchgrass particle size distributions

    SciTech Connect

    Bitra, V.S.P.; Womac, A.R.; Yang, Y.T.; Igathinathane, C.; Miu, P.I; Chevanan, Nehru; Sokhansanj, Shahabaddine

    2009-06-01

    Biomass particle size impacts handling, storage, conversion, and dust control systems. Switchgrass (Panicum virgatum L.) particle size distributions created by a knife mill were determined for integral classifying screen sizes from 12.7 to 50.8 mm, operating speeds from 250 to 500 rpm, and mass input rates from 2 to 11 kg/min. Particle distributions were classified with standardized sieves for forage analysis that included horizontal sieving motion with machined-aluminum sieves of thickness proportional to sieve opening dimensions. Then, a wide range of analytical descriptors were examined to mathematically represent the range of particle sizes in the distributions. Correlation coefficient of geometric mean length with knife mill screen size, feed rate, and speed were 0.872, 0.349, and 0.037, respectively. Hence, knife mill screen size largely determined particle size of switchgrass chop. Feed rate had an unexpected influence on particle size, though to a lesser degree than screen size. The Rosin Rammler function fit the chopped switchgrass size distribution data with an R2 > 0.982. Mass relative span was greater than 1, which indicated a wide distribution of particle sizes. Uniformity coefficient was more than 4.0, which indicated a large assortment of particles and also represented a well-graded particle size distribution. Knife mill chopping of switchgrass produced strongly fine skewed mesokurtic particles with 12.7 25.4 mm screens and fine skewed mesokurtic particles with 50.8 mm screen. Results of this extensive analysis of particle sizes can be applied to selection of knife mill operating parameters to produce a particular size of switchgrass chop, and will serve as a guide for relations among the various analytic descriptors of biomass particle distributions.

  18. A sensitivity analysis of the modified chi-square ratio statistic for equivalence testing of aerodynamic particle size distribution.

    PubMed

    Weber, Benjamin; Lee, Sau L; Lionberger, Robert; Li, Bing V; Tsong, Yi; Hochhaus, Guenther

    2013-04-01

    Demonstration of equivalence in aerodynamic particle size distribution (APSD) is one key component for establishing bioequivalence of orally inhaled drug products. We previously proposed a modified version of the Chi-square ratio statistic (mCSRS) for APSD equivalence testing and demonstrated that the median of the distribution of the mCSRS (MmCSRS) is a robust metric when test (T) and reference (R) cascade impactor (CI) profiles are identical. Here, we systematically evaluate the behavior of the MmCSRS when T and R CI profiles differ from each other in their mean deposition and variability on a single and multiple sites. All CI profiles were generated by Monte-Carlo simulations based upon modified actual CI data. Twenty thousand sets of 30 T and 30 R CI profiles were simulated for each scenario, and the behavior of the MmCSRS was correlated to metrics that characterize the difference between T and R product in mean deposition and variability. The two key findings were, first, that the MmCSRS is more sensitive to difference between T and R CI profiles on high deposition sites, and second, that a cut-off value for APSD equivalence testing based on the MmCSRS needs to be scaled on the variability of the R product. The former is considered as beneficial for equivalence testing of CI profiles as it decreases the likelihood of failing identical CI profiles by chance, in part, due to increasing analytical variability associated with lower deposition sites. The latter is expected to be important for consistently being able to discriminate equivalent from inequivalent CI profiles.

  19. Analysis of the one-dimensional Yut-Nori game: Winning strategy and avalanche-size distribution

    NASA Astrophysics Data System (ADS)

    Park, Hye Jin; Sim, Hasung; Jo, Hang-Hyun; Kim, Beom Jun

    2013-10-01

    In the Korean traditional board game Yut-Nori, teams compete by moving their pieces on a two-dimensional game board, and the team whose all pieces complete a round trip on the board wins. In every round, teams throw four wooden sticks of the shape of half-cut cylinders and the number of sticks that show belly sides, i.e., the flat sides, determines the number of steps the team's piece can advance on the board. It is possible to pile up one team's pieces if their sites are identical so that pieces as a group can move together afterwards (piling). If a team's piece(s) arrives at a site occupied by an opponent's piece(s), it is caught and removed from the board, and the team is given one more chance to throw the sticks and proceed (catching). For simplicity, we simulate this game on a one-dimensional board with the same number of sites as the original game and show that catching is a more advantageous strategy than piling to win. We also study the avalanche-size distribution in the thermodynamic limit and find that it follows an exponential form.

  20. Size dependent pore size distribution of shales by gas physisorption

    NASA Astrophysics Data System (ADS)

    Roshan, Hamid; Andersen, Martin S.; Yu, Lu; Masoumi, Hossein; Arandian, Hamid

    2017-04-01

    Gas physisorption, in particular nitrogen adsorption-desorption, is a traditional technique for characterization of geomaterials including the organic rich shales. The low pressure nitrogen is used together with adsorption-desorption physical models to study the pore size distribution (PSD) and porosity of the porous samples. The samples are usually crushed to a certain fragment size to measure these properties however there is not yet a consistent standard size proposed for sample crushing. Crushing significantly increases the surface area of the fragments e.g. the created surface area is differentiated from that of pores using BET technique. In this study, we show that the smaller fragment sizes lead to higher cumulative pore volume and smaller pore diameters. It is also shown that some of the micro-pores are left unaccounted because of the correction of the external surface area. In order to illustrate this, the nitrogen physisorption is first conducted on the identical organic rich shale samples with different sizes: 20-25, 45-50 and 63-71 µm. We then show that such effects are not only a function of pore structure changes induced by crushing, but is linked to the inability of the physical models in differentiating between the external surface area (BET) and micro-pores for different crushing sizes at relatively low nitrogen pressure. We also discuss models currently used in nano-technology such as t-method to address this issue and their advantages and shortcoming for shale rock characterization.

  1. Body size, body composition and fat distribution: comparative analysis of European, Maori, Pacific Island and Asian Indian adults.

    PubMed

    Rush, Elaine C; Freitas, Ismael; Plank, Lindsay D

    2009-08-01

    Although there is evidence that Asian Indians, Polynesians and Europeans differ in their body fat (BF)-BMI relationships, detailed comparative analysis of their underlying body composition and build characteristics is lacking. We investigated differences in the relationships between body fatness and BMI, fat distribution, muscularity, bone mineral mass, leg length and age-related changes in body composition between these ethnic groups. Cross-sectional analysis of 933 European, Maori, Pacific Island and Asian Indian adult volunteers was performed for total and percentage of BF, abdominal fat, thigh fat, appendicular muscle mass, bone mineral content and leg length measured by dual-energy X-ray absorptiometry. Asian Indian men and women (BMI of 24 and 26 kg/m2, respectively) had the same percentage of BF as Europeans with a BMI of 30 kg/m2 or Pacific men and women with BMI of 34 and 35 kg/m2, respectively. Asian Indians had more fat, both total and in the abdominal region, with less lean mass, skeletal muscle and bone mineral than all other ethnic groups. Leg length was relatively longer in Pacific men and Asian and Pacific women than in other ethnic groups. In Asian Indians, abdominal fat increased with increasing age, while the percentage of BF showed little change. In the other ethnic groups, both abdominal and total BF increased with age. In conclusion, ethnic differences in fat distribution, muscularity, bone mass and leg length may contribute to ethnic-specific relationships between body fatness and BMI. The use of universal BMI cut-off points may not be appropriate for the comparison of obesity prevalence between ethnic groups.

  2. Characterization of Grain Size Distribution and Grain Shape Analysis of Tephra Deposits: a New Approach Based on Automated Microscopy and Image Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Volentik, A. C.; Bonadonna, C.; Connor, C. B.

    2006-12-01

    Grain size distribution (GSD) is a key parameter in physical volcanology, not only for the characterization of tephra deposits, but also for the application of numerical models and for the compilation of reliable tephra hazard assessments. In addition, grain shape analysis (GSA) has important implications in the determination of particle settling velocities, crucial factor in tephra dispersal models. We present a new method for the determination of reliable GSD together with 2D GSA for volcanic particle ranging between 0.5 μ and 2 mm in size (from 13 to -1 in the Φ scale): the application of the Malvern PharmaVision 830 (PVS) automated optical device. PVS provides several morphological parameters that can be used to determine GSD of volcanic ash. We have compared GSD results for 3 different morphological parameters (mean diameter, maximum length and width) of three samples collected along a dispersal axis of a Plinian eruption of Pululagua volcano (Ecuador). GSD based on particle width gives the best fit with GSD data resulting from sieving techniques and is thus recommended when GSD of volcanic ash (< 2mm) has to be combined with GSD of volcanic lapilli (> 2mm) that require hand sieving. GSA data were investigated to characterize morphology variations with magma composition and with distance from the volcanic vent. In fact, GSA results were analyzed for 3 different tephra deposits with different magma composition: (i) Cerro Negro (basaltic), (ii) Pululagua (dacitic) and (iii) Bishop Tuff (rhyolitic). In particular, we have found that particle intensity shows the same trend for all deposits, whereas trends of roundness and convexity are different for different magma compositions, suggesting that roundness and convexity are strongly dependent on magma fragmentation mechanisms. Preliminary results have also shown that mean roundness, mean convexity and mean intensity do not vary significantly with distance from vent for Pululagua. Finally, an attempt has been made

  3. Analysis of Molecular Size Distributions of Cellulose Molecules during Hydrolysis of Cellulose by Recombinant Cellulomonas fimi β-1,4-Glucanases

    PubMed Central

    Stålbrand, Henrik; Mansfield, Shawn D.; Saddler, John N.; Kilburn, Douglas G.; Warren, R. Antony J.; Gilkes, Neil R.

    1998-01-01

    Four β-1,4-glucanases (cellulases) of the cellulolytic bacterium Cellulomonas fimi were purified from Escherichia coli cells transformed with recombinant plasmids. Previous analyses using soluble substrates had suggested that CenA and CenC were endoglucanases while CbhA and CbhB resembled the exo-acting cellobiohydrolases produced by cellulolytic fungi. Analysis of molecular size distributions during cellulose hydrolysis by the individual enzymes confirmed these preliminary findings and provided further evidence that endoglucanase CenC has a more processive hydrolytic activity than CenA. The significant differences between the size distributions obtained during hydrolysis of bacterial microcrystalline cellulose and acid-swollen cellulose can be explained in terms of the accessibility of β-1,4-glucan chains to enzyme attack. Endoglucanases and cellobiohydrolases were much more easily distinguished when the acid-swollen substrate was used. PMID:9647802

  4. Activity size distribution of some natural radionuclides.

    PubMed

    Mohery, M; Abdallah, A M; Al-Amoudi, Z M; Baz, S S

    2014-03-01

    In this study, the results concerning the activity size distribution of the long-lived ((210)Pb) radon decay product aerosols and the thoron decay product aerosols ((212)Pb) and ((7)Be) of the outdoor atmosphere are presented. Also, the mass size distribution of the aerosol particles is determined. The low-pressure Berner cascade impactor Model 20/0.015 was used as a sampling device. The activity size distribution of these radionuclides was determined by one log-normal distribution (accumulation mode) whereas the mass size distribution was by two log-normal distributions (accumulation and coarse mode). The activity median aerodynamic diameter (AMAD) of (212)Pb was found to be 305 nm with a geometric standard deviation (σg) of 2.41. The specific air activity concentration of (212)Pb was found to be 0.14 ± 0.012 Bq m(-3). An AMAD of (210)Pb of 610 nm with σg of 1.8 was determined, whereas that of 550 nm with σg of 1.97 was determined for (7)Be. The specific air activity concentration of (210)Pb and (7)Be was found to be 0.0016±2.5×10(-4) and 0.00348 ± 4×10(-4) Bq m(-3), respectively. Using a dosimetric model, the total deposition fraction as well as the total equivalent dose has been evaluated considering the observed parameters of the activity size distribution of (212)Pb. At a total deposition fraction of ∼21 %, the total equivalent dose was found to be 0.41 µSv.

  5. Martian crater size distributions and terrain age

    NASA Technical Reports Server (NTRS)

    Barlow, N. G.; Strom, R. G.

    1984-01-01

    The crater size/frequency distributions of large ( 8 km) craters on the Moon and terrestrial planets display two very different curves representing two crater populations. The heavily cratered regions of the Moon, Mercury, and Mars show the same highly structured curve which cannot be represented by a single slope distribution function. In contrast, the lunar post mare crater population has a size/frequency distribution which differs significantly from that in the highlands over the same diameter range, and can be represented by a single-slope distribution function of -2.8 differential. On areas of martian lightly cratered northern plains, the crater population is essentially identical to that of the post mare population. This indicates that the same two families of impacting objects were responsible for the cratering records on both Moon and Mars. The thickness of mantling material varies among the various plains units, and can be calculated from the depth/diameter scaling relations for martian craters.

  6. Effect of roll compaction on granule size distribution of microcrystalline cellulose–mannitol mixtures: computational intelligence modeling and parametric analysis

    PubMed Central

    Kazemi, Pezhman; Khalid, Mohammad Hassan; Pérez Gago, Ana; Kleinebudde, Peter; Jachowicz, Renata; Szlęk, Jakub; Mendyk, Aleksander

    2017-01-01

    Dry granulation using roll compaction is a typical unit operation for producing solid dosage forms in the pharmaceutical industry. Dry granulation is commonly used if the powder mixture is sensitive to heat and moisture and has poor flow properties. The output of roll compaction is compacted ribbons that exhibit different properties based on the adjusted process parameters. These ribbons are then milled into granules and finally compressed into tablets. The properties of the ribbons directly affect the granule size distribution (GSD) and the quality of final products; thus, it is imperative to study the effect of roll compaction process parameters on GSD. The understanding of how the roll compactor process parameters and material properties interact with each other will allow accurate control of the process, leading to the implementation of quality by design practices. Computational intelligence (CI) methods have a great potential for being used within the scope of quality by design approach. The main objective of this study was to show how the computational intelligence techniques can be useful to predict the GSD by using different process conditions of roll compaction and material properties. Different techniques such as multiple linear regression, artificial neural networks, random forest, Cubist and k-nearest neighbors algorithm assisted by sevenfold cross-validation were used to present generalized models for the prediction of GSD based on roll compaction process setting and material properties. The normalized root-mean-squared error and the coefficient of determination (R2) were used for model assessment. The best fit was obtained by Cubist model (normalized root-mean-squared error =3.22%, R2=0.95). Based on the results, it was confirmed that the material properties (true density) followed by compaction force have the most significant effect on GSD. PMID:28176905

  7. Effect of roll compaction on granule size distribution of microcrystalline cellulose-mannitol mixtures: computational intelligence modeling and parametric analysis.

    PubMed

    Kazemi, Pezhman; Khalid, Mohammad Hassan; Pérez Gago, Ana; Kleinebudde, Peter; Jachowicz, Renata; Szlęk, Jakub; Mendyk, Aleksander

    2017-01-01

    Dry granulation using roll compaction is a typical unit operation for producing solid dosage forms in the pharmaceutical industry. Dry granulation is commonly used if the powder mixture is sensitive to heat and moisture and has poor flow properties. The output of roll compaction is compacted ribbons that exhibit different properties based on the adjusted process parameters. These ribbons are then milled into granules and finally compressed into tablets. The properties of the ribbons directly affect the granule size distribution (GSD) and the quality of final products; thus, it is imperative to study the effect of roll compaction process parameters on GSD. The understanding of how the roll compactor process parameters and material properties interact with each other will allow accurate control of the process, leading to the implementation of quality by design practices. Computational intelligence (CI) methods have a great potential for being used within the scope of quality by design approach. The main objective of this study was to show how the computational intelligence techniques can be useful to predict the GSD by using different process conditions of roll compaction and material properties. Different techniques such as multiple linear regression, artificial neural networks, random forest, Cubist and k-nearest neighbors algorithm assisted by sevenfold cross-validation were used to present generalized models for the prediction of GSD based on roll compaction process setting and material properties. The normalized root-mean-squared error and the coefficient of determination (R(2)) were used for model assessment. The best fit was obtained by Cubist model (normalized root-mean-squared error =3.22%, R(2)=0.95). Based on the results, it was confirmed that the material properties (true density) followed by compaction force have the most significant effect on GSD.

  8. Comparison of drop size distributions from two droplet sizing systems

    NASA Technical Reports Server (NTRS)

    Oldenburg, John R.; Ide, Robert F.

    1990-01-01

    A comparison between the Phase Doppler Particle Analyzer and the combined measurements from Particle Measuring Systems' Forward Scattering Spectrometer Probe and the Optical Array Probe was conducted in an icing wind tunnel using NASA Icing Research Tunnel spray nozzles to produce the supercooled water droplet cloud. Clouds having a range of volume median diameters from 10 to greater than 50 microns were used for the instrument comparisons. A volume median diameter was calculated from combining the droplet distributions of the Optical Array Probe and the Forward Scattering Spectrometer Probe. A comparison of the combined volume median diameters and the Phase Doppler Particle Analyzer volume median diameters showed agreement from 10 microns up to 30 microns. Typical drop size distributions from the Phase Doppler Particle Analyzer, the Forward Scattering Spectrometer Probe, and Optical Array Probe are presented for several median volume diameters. A comparison of the distributions illustrates regions of the distributions where there is good agreement and other regions where there are discrepancies between the Phase Doppler Particle Analyzer and the Particle Measuring Systems' droplet size instruments.

  9. Size distributions in two porous chondritic micrometeorites

    NASA Astrophysics Data System (ADS)

    Rietmeijer, F. J. M.

    1993-06-01

    Quantitative size measurements of granular units (GUs), and nm-sized minerals in these units, in two porous chondritic micrometeorites are investigated. The matrix of these micrometeorites consist of loosely packed, 0.1 micron-sized, GUs. These objects were a major component of the solar nebula dust that accreted into protoplanets. The matrix in micrometeorite W7010*A2 has a fractal dimension with a small coefficient that supports efficient sticking of carbon-rich GUs during accretion. The fractal nature of the matrix provides a way to calculate the density using the aggregate size. The resulting very low density for porous chondritic micrometeorites is 0.08-0.14 g/cu cm, which supports the view that they are the solid debris from unconsolidated solar system bodies. Chondritic GUs contain ultrafine olivines, pyroxenes, and sulfides, embedded in hydrocarbons and amorphous carbons. Nanocrystals in the micrometeorites W7010*A2 and U2015*B show log normal size distributions. The high incidence of disk-shaped grains, a changeover from disk-shaped to euhedral grains, the unevolved nature of the size distributions, and multiple populations for grains less than 127 nm in size, are consistent with continuous postaccretion nucleation and growth in amorphous GUs, including coarsening via Ostwald ripening.

  10. PARTICLE SIZE DISTRIBUTIONS FOR AN OFFICE AEROSOL

    EPA Science Inventory

    The article discusses an evaluation of the effect of percent outdoor air supplied and occupation level on the particle size distributions and mass concentrations for a typical office building. (NOTE: As attention has become focused on indoor air pollution control, it has become i...

  11. PARTICLE SIZE DISTRIBUTIONS FOR AN OFFICE AEROSOL

    EPA Science Inventory

    The article discusses an evaluation of the effect of percent outdoor air supplied and occupation level on the particle size distributions and mass concentrations for a typical office building. (NOTE: As attention has become focused on indoor air pollution control, it has become i...

  12. Raindrop Size Distribution Measurements in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Tokay, Ali; Bashor, Paul G.; Habib, Emad; Kasparis, Takis

    2008-01-01

    Characteristics of the raindrop size distribution in seven tropical cyclones have been studied through impact-type disdrometer measurements at three different sites during the 2004-06 Atlantic hurricane seasons. One of the cyclones has been observed at two different sites. High concentrations of small and/or midsize drops were observed in the presence or absence of large drops. Even in the presence of large drops, the maximum drop diameter rarely exceeded 4 mm. These characteristics of raindrop size distribution were observed in all stages of tropical cyclones, unless the storm was in the extratropical stage where the tropical cyclone and a midlatitude frontal system had merged. The presence of relatively high concentrations of large drops in extratropical cyclones resembled the size distribution in continental thunderstorms. The integral rain parameters of drop concentration, liquid water content, and rain rate at fixed reflectivity were therefore lower in extratropical cyclones than in tropical cyclones. In tropical cyclones, at a disdrometercalculated reflectivity of 40 dBZ, the number concentration was 700 plus or minus 100 drops m(sup -3), while the liquid water content and rain rate were 0.90 plus or minus 0.05 g m(sup -3) and 18.5 plus or minus 0.5 mm h(sup -1), respectively. The mean mass diameter, on the other hand, was 1.67 plus or minus 0.3 mm. The comparison of raindrop size distributions between Atlantic tropical cyclones and storms that occurred in the central tropical Pacific island of Roi-Namur revealed that the number density is slightly shifted toward smaller drops, resulting in higher-integral rain parameters and lower mean mass and maximum drop diameters at the latter site. Considering parameterization of the raindrop size distribution in tropical cyclones, characteristics of the normalized gamma distribution parameters were examined with respect to reflectivity. The mean mass diameter increased rapidly with reflectivity, while the normalized

  13. Raindrop Size Distribution Measurements in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Tokay, Ali; Bashor, Paul G.; Habib, Emad; Kasparis, Takis

    2008-01-01

    Characteristics of the raindrop size distribution in seven tropical cyclones have been studied through impact-type disdrometer measurements at three different sites during the 2004-06 Atlantic hurricane seasons. One of the cyclones has been observed at two different sites. High concentrations of small and/or midsize drops were observed in the presence or absence of large drops. Even in the presence of large drops, the maximum drop diameter rarely exceeded 4 mm. These characteristics of raindrop size distribution were observed in all stages of tropical cyclones, unless the storm was in the extratropical stage where the tropical cyclone and a midlatitude frontal system had merged. The presence of relatively high concentrations of large drops in extratropical cyclones resembled the size distribution in continental thunderstorms. The integral rain parameters of drop concentration, liquid water content, and rain rate at fixed reflectivity were therefore lower in extratropical cyclones than in tropical cyclones. In tropical cyclones, at a disdrometercalculated reflectivity of 40 dBZ, the number concentration was 700 plus or minus 100 drops m(sup -3), while the liquid water content and rain rate were 0.90 plus or minus 0.05 g m(sup -3) and 18.5 plus or minus 0.5 mm h(sup -1), respectively. The mean mass diameter, on the other hand, was 1.67 plus or minus 0.3 mm. The comparison of raindrop size distributions between Atlantic tropical cyclones and storms that occurred in the central tropical Pacific island of Roi-Namur revealed that the number density is slightly shifted toward smaller drops, resulting in higher-integral rain parameters and lower mean mass and maximum drop diameters at the latter site. Considering parameterization of the raindrop size distribution in tropical cyclones, characteristics of the normalized gamma distribution parameters were examined with respect to reflectivity. The mean mass diameter increased rapidly with reflectivity, while the normalized

  14. Particle size and shape distributions of hammer milled pine

    SciTech Connect

    Westover, Tyler Lott; Matthews, Austin Colter; Williams, Christopher Luke; Ryan, John Chadron Benjamin

    2015-04-01

    Particle size and shape distributions impact particle heating rates and diffusion of volatized gases out of particles during fast pyrolysis conversion, and consequently must be modeled accurately in order for computational pyrolysis models to produce reliable results for bulk solid materials. For this milestone, lodge pole pine chips were ground using a Thomas-Wiley #4 mill using two screen sizes in order to produce two representative materials that are suitable for fast pyrolysis. For the first material, a 6 mm screen was employed in the mill and for the second material, a 3 mm screen was employed in the mill. Both materials were subjected to RoTap sieve analysis, and the distributions of the particle sizes and shapes were determined using digital image analysis. The results of the physical analysis will be fed into computational pyrolysis simulations to create models of materials with realistic particle size and shape distributions. This milestone was met on schedule.

  15. Multi-scale analysis in carbonates by X-ray microtomography: Characterization of the porosity and pore size distribution

    NASA Astrophysics Data System (ADS)

    Fernandes, Jaquiel S.; Nagata, Rodrigo; Moreira, Anderson C.; Fernandes, Celso P.; Appoloni, Carlos R.

    2013-05-01

    The porous systems of reservoir rocks present a complex geometry, involving aspects of shape of pores (morphology) and connectivity between the pores (topology). The macroscopic physical properties of these materials are strongly dependent of their microstructures. Based on these aspects, the present study has as main objective the characterization of the porous system geometry and computational determination of petrophysics properties of carbonate reservoir rocks through the X-ray microtomography methodology. Samples were microtomographed with the microtomographs Skyscan model 1172, installed at the PETROBRAS Research and Development Center (CENPES), Rio de Janeiro-RJ, Brazil and model 1173, installed at Sedimentary Geology Laboratory (LAGESD) in the Federal University of Rio de Janeiro (UFRJ). Two samples of carbonates were measured, Travertine and Dolomite, with spatial resolutions of 7 μm and 9.8 μm and 1.3 μm, 7 μm and 17 μm, respectively for the travertine and dolomite. With the data collected in the acquisitions, 900 transversal sections were reconstructed for each one of the referred resolutions. For the sample of dolomite, the average porosity found was 21.64%, 20.92% and 15.97% for resolutions of 1.3 μm, 7 μm and 17 μm, respectively. For the sample of travertine, the average porosity was 7.80 % and 7.52 % for resolutions of 7 μm and 9.8 μm, respectively. For the sample of dolomite, the pore size distribution showed that 50 % of the porous phase has pores with radius up to 37.6 μm, 84.6 μm and 84.4 μm, for the spatial resolutions of 1.3 μm, 7 μm and 17 μm, respectively. For the sample of travertine, 50 % of the pores have radius up to 148.1 μm and 158.1 μm, for the spatial resolutions of 7 μm and 9.8 μm.

  16. Body size distributions signal a regime shift in a lake ...

    EPA Pesticide Factsheets

    Communities of organisms, from mammals to microorganisms, have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at multiple spatial and temporal scales. In this study, we assessed whether body size patterns serve as an indicator of a threshold between alternative regimes. Over the past 7000 years, the biological communities of Foy Lake (Montana,USA) have undergone a major regime shift owing to climate change. We used a palaeoecological record of diatom communities to estimate diatom sizes, and then analysed the discontinuous distribution of organism sizes over time. We used Bayesian classification and regression tree models to determine that all time intervals exhibited aggregations of sizes separated by gaps in the distribution and found a significant change in diatom body size distributions approximately 150 years before the identified ecosystem regime shift. We suggest that discontinuity analysis is a useful addition to the suite of tools for the detection of early warning signals of regime shifts. Communities of organisms from mammals to microorganisms have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at discrete spatial and temporal scales within ecosystems. Here, a paleoecological record of diatom community change is use

  17. Multivariate data analysis as a semi-quantitative tool for interpretive evaluation of comparability or equivalence of aerodynamic particle size distribution profiles.

    PubMed

    Shi, Shuai; Hickey, Anthony J

    2009-01-01

    The purpose of this article is to investigate the performance of multivariate data analysis, especially orthogonal partial least square (OPLS) analysis, as a semi-quantitative tool to evaluate the comparability or equivalence of aerodynamic particle size distribution (APSD) profiles of orally inhaled and nasal drug products (OINDP). Monte Carlo simulation was employed to reconstitute APSD profiles based on 55 realistic scenarios proposed by the Product Quality Research Institute (PQRI) working group. OPLS analyses with different data pretreatment methods were performed on each of the reconstituted profiles. Compared to unit-variance scaling, equivalence determined based on OPLS analysis with Pareto scaling was shown to be more consistent with the working group assessment. Chi-square statistics was employed to compare the performance of OPLS analysis (Pareto scaling) with that of the combination test (i.e., chi-square ratio statistics and population bioequivalence test for impactor-sized mass) in terms of achieving greater consistency with the working group evaluation. A p value of 0.036 suggested that OPLS analysis with Pareto scaling may be more predictive than the combination test with respect to consistency. Furthermore, OPLS analysis may also be employed to analyze part of the APSD profiles that contribute to the calculation of the mass median aerodynamic diameter. Our results show that OPLS analysis performed on partial deposition sites do not interfere with the performance on all deposition sites.

  18. Size distributions of submicrometer aerosols from cooking

    SciTech Connect

    Li, C.S.; Lin, W.H.; Jeng, F.T. )

    1993-01-01

    Although gas stove usage varies from country to country, it is still one of the major indoor combustion sources. In order to assess the health effects of using gas stoves, the physical characteristics of the particle emissions from cooking were conducted in a first-floor apartment in the Taipei area. The particle size distributions from scrambling eggs, frying chicken, and cooking soup were measured in the kitchen by a high resolution particle sizer, which could measure the particles in the size range of 0.01 [mu]m to 1 [mu]m. The concentrations of the submicrometer particles increased significantly from 15,000 cm[sup [minus]3] to 150,000 cm[sup [minus]3] during cooking. Additionally, the ultrafine particles constituted 60%--70% of the total submicron aerosols. The changes in the size distributions and the concentrations of the submicrometer aerosols before, during, and after the aerosol generations were compared. On the average, the median diameters of scrambling eggs, frying chicken, cooking soup, and of the background conditions were 40 nm, 50 nm, 30 nm, and 70 nm, respectively. Regarding the surface area-weighted size distributions, the surface median diameters of the four situations were 180 nm, 300 nm, 150 nm, and 220 nm, respectively. Furthermore, the volume median diameters in the conditions mentioned above were almost similar, namely 300--350 nm. 10 refs., 6 figs., 2 tabs.

  19. Modelling complete particle-size distributions from operator estimates of particle-size

    NASA Astrophysics Data System (ADS)

    Roberson, Sam; Weltje, Gert Jan

    2014-05-01

    Estimates of particle-size made by operators in the field and laboratory represent a vast and relatively untapped data archive. The wide spatial distribution of particle-size estimates makes them ideal for constructing geological models and soil maps. This study uses a large data set from the Netherlands (n = 4837) containing both operator estimates of particle size and complete particle-size distributions measured by laser granulometry. This study introduces a logit-based constrained-cubic-spline (CCS) algorithm to interpolate complete particle-size distributions from operator estimates. The CCS model is compared to four other models: (i) a linear interpolation; (ii) a log-hyperbolic interpolation; (iii) an empirical logistic function; and (iv) an empirical arctan function. Operator estimates were found to be both inaccurate and imprecise; only 14% of samples were successfully classified using the Dutch classification scheme for fine sediment. Operator estimates of sediment particle-size encompass the same range of values as particle-size distributions measured by laser analysis. However, the distributions measured by laser analysis show that most of the sand percentage values lie between zero and one, so the majority of the variability in the data is lost because operator estimates are made to the nearest 1% at best, and more frequently to the nearest 5%. A method for constructing complete particle-size distributions from operator estimates of sediment texture using a logit constrained cubit spline (CCS) interpolation algorithm is presented. This model and four other previously published methods are compared to establish the best approach to modelling particle-size distributions. The logit-CCS model is the most accurate method, although both logit-linear and log-linear interpolation models provide reasonable alternatives. Models based on empirical distribution functions are less accurate than interpolation algorithms for modelling particle-size distributions in

  20. Company size distribution in different countries

    NASA Astrophysics Data System (ADS)

    Ramsden, J. J.; Kiss-Haypál, Gy.

    2000-03-01

    The distribution of companies in a country, ranked in order of size (annual net revenue) s, follows the simplified canonical law s r∼(r+ρ) -1/θ remarkably well, where r is the rank, and θ and ρ are the parameters of the distribution. These parameters have been determined for 20 countries in America, Asia and Europe. Significant differences between countries are found. Neither θ nor ρ appears to correlate well with traditional economic indicators; indeed some countries often thought to be economically and politically, but not necessarily socially, similar show surprising differences, suggesting that wealth and prosperity are influenced by hidden layers hitherto inaccessible through standard economic theory.

  1. Online particle size distribution estimation of a mixture of similar sized particles with acoustic emissions

    NASA Astrophysics Data System (ADS)

    Nsugbe, Ejay; Starr, Andrew; Jennions, Ian; Ruiz Carcel, Cristobal

    2017-08-01

    Particle processing plants regard the Particle Size Distribution (PSD) as a key quality factor as it influences the bulk and flow properties of the particles. In this work, Acoustic Emission (AE) is used to estimate the PSD of a mixture that comprise of similar sized particles. The experiments involved the use of regular sized particles (glass beads) and with the aid of a time domain based threshold analysis of the particle impacts the PSD of the mixtures could be estimated.

  2. Tracing Particle Size Distribution Curves Using an Analogue Circuit.

    ERIC Educational Resources Information Center

    Bisschop, F. De; Segaert, O.

    1986-01-01

    Proposes an analog circuit for use in sedimentation analysis of finely divided solid materials. Discusses a method of particle size distribution analysis and provides schematics of the circuit with list of components as well as a discussion about the operation of the circuit. (JM)

  3. Tracing Particle Size Distribution Curves Using an Analogue Circuit.

    ERIC Educational Resources Information Center

    Bisschop, F. De; Segaert, O.

    1986-01-01

    Proposes an analog circuit for use in sedimentation analysis of finely divided solid materials. Discusses a method of particle size distribution analysis and provides schematics of the circuit with list of components as well as a discussion about the operation of the circuit. (JM)

  4. Particle Size Distributions in Atmospheric Clouds

    DTIC Science & Technology

    2003-12-01

    UNCLASSIFIED Center for Turbulence Research 39 Annual Research Briefs 2003 Particle size distributions in atmospheric clouds By Roberto Paoli & Karim...atmospheric turbulence is an important, though complex, problem in cloud physics ( Shaw 2003). From a computational point of view, two major factors...contribute to this complexity. First is the very high turbulence Reynolds number and the large range of spatial scales (Vaillancourt & Yau 2000; Shaw 2003

  5. Genome Sizes and the Benford Distribution

    PubMed Central

    Friar, James L.; Goldman, Terrance; Pérez–Mercader, Juan

    2012-01-01

    Background Data on the number of Open Reading Frames (ORFs) coded by genomes from the 3 domains of Life show the presence of some notable general features. These include essential differences between the Prokaryotes and Eukaryotes, with the number of ORFs growing linearly with total genome size for the former, but only logarithmically for the latter. Results Simply by assuming that the (protein) coding and non-coding fractions of the genome must have different dynamics and that the non-coding fraction must be particularly versatile and therefore be controlled by a variety of (unspecified) probability distribution functions (pdf’s), we are able to predict that the number of ORFs for Eukaryotes follows a Benford distribution and must therefore have a specific logarithmic form. Using the data for the 1000+ genomes available to us in early 2010, we find that the Benford distribution provides excellent fits to the data over several orders of magnitude. Conclusions In its linear regime the Benford distribution produces excellent fits to the Prokaryote data, while the full non-linear form of the distribution similarly provides an excellent fit to the Eukaryote data. Furthermore, in their region of overlap the salient features are statistically congruent. This allows us to interpret the difference between Prokaryotes and Eukaryotes as the manifestation of the increased demand in the biological functions required for the larger Eukaryotes, to estimate some minimal genome sizes, and to predict a maximal Prokaryote genome size on the order of 8–12 megabasepairs.These results naturally allow a mathematical interpretation in terms of maximal entropy and, therefore, most efficient information transmission. PMID:22629319

  6. Size distribution of ions in atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Krivácsy, Z.; Molnár, Á.

    The aim of this paper is to present data about the concentration and size distribution of ions in atmospheric aerosol under slightly polluted urban conditions in Hungary. Concentration of inorganic cations (ammonium, sodium, potassium, calcium, magnesium), inorganic anions (sulfate, nitrate, chloride, carbonate) and organic acids (oxalic, malonic, succinic, formic and acetic acid) for 8 particle size range between 0.0625 and 16 μm were determined. As was the case for ammonium, sulfate and nitrate, the organic acids were mostly found in the fine particle size range. Potassium and chloride were rather uniformly distributed between fine and coarse particles. Sodium, calcium, magnesium and carbonate were practically observed in the coarse mode. The results obtained for the summer and the winter half-year were also compared. The mass concentrations were recalculated in equivalents, and the ion balance was found to be reasonable in most cases. Measurement of the pH of the aerosol extracts indicates that the aerosol is acidic in the fine mode, but alkaline in the coarse particle size range.

  7. A statistical approach to estimate the 3D size distribution of spheres from 2D size distributions

    USGS Publications Warehouse

    Kong, M.; Bhattacharya, R.N.; James, C.; Basu, A.

    2005-01-01

    Size distribution of rigidly embedded spheres in a groundmass is usually determined from measurements of the radii of the two-dimensional (2D) circular cross sections of the spheres in random flat planes of a sample, such as in thin sections or polished slabs. Several methods have been devised to find a simple factor to convert the mean of such 2D size distributions to the actual 3D mean size of the spheres without a consensus. We derive an entirely theoretical solution based on well-established probability laws and not constrained by limitations of absolute size, which indicates that the ratio of the means of measured 2D and estimated 3D grain size distribution should be r/4 (=.785). Actual 2D size distribution of the radii of submicron sized, pure Fe0 globules in lunar agglutinitic glass, determined from backscattered electron images, is tested to fit the gamma size distribution model better than the log-normal model. Numerical analysis of 2D size distributions of Fe0 globules in 9 lunar soils shows that the average mean of 2D/3D ratio is 0.84, which is very close to the theoretical value. These results converge with the ratio 0.8 that Hughes (1978) determined for millimeter-sized chondrules from empirical measurements. We recommend that a factor of 1.273 (reciprocal of 0.785) be used to convert the determined 2D mean size (radius or diameter) of a population of spheres to estimate their actual 3D size. ?? 2005 Geological Society of America.

  8. Atmospheric Ion Clusters: Properties and Size Distributions

    NASA Astrophysics Data System (ADS)

    D'Auria, R.; Turco, R. P.

    2002-12-01

    Ions are continuously generated in the atmosphere by the action of galactic cosmic radiation. Measured charge concentrations are of the order of 103 ~ {cm-3} throughout the troposphere, increasing to about 5 x 103 ~ {cm-3} in the lower stratosphere [Cole and Pierce, 1965; Paltridge, 1965, 1966]. The lifetimes of these ions are sufficient to allow substantial clustering with common trace constituents in air, including water, nitric and sulfuric acids, ammonia, and a variety of organic compounds [e.g., D'Auria and Turco, 2001 and references cited therein]. The populations of the resulting charged molecular clusters represent a pre-nucleation phase of particle formation, and in this regard comprise a key segment of the over-all nucleation size spectrum [e.g., Castleman and Tang, 1972]. It has been suggested that these clusters may catalyze certain heterogeneous reactions, and given their characteristic crystal-like structures may act as freezing nuclei for supercooled droplets. To investigate these possibilities, basic information on cluster thermodynamic properties and chemical kinetics is needed. Here, we present new results for several relevant atmospheric ion cluster families. In particular, predictions based on quantum mechanical simulations of cluster structure, and related thermodynamic parameters, are compared against laboratory data. We also describe a hybrid approach for modeling cluster sequences that combines laboratory measurements and quantum predictions with the classical liquid droplet (Thomson) model to treat a wider range of cluster sizes. Calculations of cluster mass distributions based on this hybrid model are illustrated, and the advantages and limitations of such an analysis are summarized. References: Castelman, A. W., Jr., and I. N. Tang, Role of small clusters in nucleation about ions, J. Chem. Phys., 57, 3629-3638, 1972. Cole, R. K., and E. T. Pierce, Electrification in the Earth's atmosphere for altitudes between 0 and 100 kilometers, J

  9. A new strategy for pressed powder eye shadow analysis: allergenic metal ion content and particle size distribution.

    PubMed

    Contado, Catia; Pagnoni, Antonella

    2012-08-15

    Nine cheap eye shadow products were analyzed through graphite furnace atomic absorption spectrometry (GF-AAS) to quantify their Cr, Co and Ni contents, all known to be skin sensitizers. In many cases, the concentrations were higher than 1 or 5 ppm (μg/g), i.e. the limits recommended in the scientific literature to minimize the risk of reaction in particularly sensitive subjects. In most cases, the concentration of Cr was higher than that of Ni and Co, up to a limit case of 150 mg/g. In this particular sample, the potential amount of Cr that could be released in ionic form was determined in sweat simulating solutions by GF-AAS and confirmed through a specific spectrofluorimetric method; the results indicated the presence of approximately 80-90 ppb (ng/g) of Cr(3+). The water dispersible particles were isolated from the eye shadow powders through a simple solvent extraction procedure. The aqueous suspensions were then sorted through sedimentation field flow fractionation (SdFFF) and the particles sizes were calculated from experimental fractograms using theory. For the most part, the computed sizes were in the micron range, as confirmed by some SEM photographs taken on fractions collected during the separations. The SdFFF coupled off-line with the GFAAS enabled elemental characterization of pigment particles as a function of size. This finding reduces the concern that the ingredients of such makeup formulations may contain nanoparticles. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. The invariances of power law size distributions.

    PubMed

    Frank, Steven A

    2016-01-01

    Size varies. Small things are typically more frequent than large things. The logarithm of frequency often declines linearly with the logarithm of size. That power law relation forms one of the common patterns of nature. Why does the complexity of nature reduce to such a simple pattern? Why do things as different as tree size and enzyme rate follow similarly simple patterns? Here I analyze such patterns by their invariant properties. For example, a common pattern should not change when adding a constant value to all observations. That shift is essentially the renumbering of the points on a ruler without changing the metric information provided by the ruler. A ruler is shift invariant only when its scale is properly calibrated to the pattern being measured. Stretch invariance corresponds to the conservation of the total amount of something, such as the total biomass and consequently the average size. Rotational invariance corresponds to pattern that does not depend on the order in which underlying processes occur, for example, a scale that additively combines the component processes leading to observed values. I use tree size as an example to illustrate how the key invariances shape pattern. A simple interpretation of common pattern follows. That simple interpretation connects the normal distribution to a wide variety of other common patterns through the transformations of scale set by the fundamental invariances.

  11. The invariances of power law size distributions

    PubMed Central

    Frank, Steven A.

    2016-01-01

    Size varies. Small things are typically more frequent than large things. The logarithm of frequency often declines linearly with the logarithm of size. That power law relation forms one of the common patterns of nature. Why does the complexity of nature reduce to such a simple pattern? Why do things as different as tree size and enzyme rate follow similarly simple patterns? Here I analyze such patterns by their invariant properties. For example, a common pattern should not change when adding a constant value to all observations. That shift is essentially the renumbering of the points on a ruler without changing the metric information provided by the ruler. A ruler is shift invariant only when its scale is properly calibrated to the pattern being measured. Stretch invariance corresponds to the conservation of the total amount of something, such as the total biomass and consequently the average size. Rotational invariance corresponds to pattern that does not depend on the order in which underlying processes occur, for example, a scale that additively combines the component processes leading to observed values. I use tree size as an example to illustrate how the key invariances shape pattern. A simple interpretation of common pattern follows. That simple interpretation connects the normal distribution to a wide variety of other common patterns through the transformations of scale set by the fundamental invariances. PMID:27928497

  12. Fine-Scale Topographic Analysis of Rock Size Distributions Derived from High-Resolution Ground-Based LiDAR

    NASA Astrophysics Data System (ADS)

    Finnegan, D. C.; Arcone, S. A.; Bulmer, M. H.; Anderson, S. W.

    2007-05-01

    Quantitative factors such as RMS height, correlation lengths and surface slope derived from fine-scale topographic datasets hold the potential for characterizing surface morphology in relation to its underlying geologic processes. In an attempt to better understand the relationships between topographic roughness characteristics and geologic processes responsible for creating a distinct surface morphology, we utilize ground-based terrestrial LiDAR and coincidental orthorectified imagery to quantify the variability in RMS heights and correlation lengths. The purpose of this study is to understand directly how various topographic data collection techniques such as LiDAR and manual field-based measurements compare to one another and which techniques are most appropriate for characterizing topography at various scales. Topographic data from several platforms were acquired over desert surfaces in the Mojave Desert near Palm Springs, California and southwestern Arizona. The desert surfaces imaged in the Mojave contained average rock sizes ranging from decimeters to a maximum size near one meter and revealed wide variations in RMS heights and correlation lengths, in keeping with the highly variable surface. Alternately, the Arizona site exhibits less topographic variability and consistent statistics. The data are useful for characterizing the roughness of surfaces for a variety of disciplines, such as penetration of remote sensing signals, upwelling of radiation and characterizing the genetic origin of surfaces. Furthermore, these data become essential to airborne and ground-based imaging sensors and understanding how topographic irregularities affect data fidelity.

  13. Efficient approximation of the cluster size distribution in binary condensation

    NASA Astrophysics Data System (ADS)

    van Putten, Dennis S.; Sidin, Ryan S. R.; Hagmeijer, Rob

    2010-05-01

    We propose a computationally efficient method for the calculation of the binary cluster size distribution. This method is based on the phase path analysis algorithm, which was originally derived for single-component condensation. We extend this method by constructing the binary general dynamic equation, which introduces clusters at a point in two component n1,n2-space. The location of this source point is determined by the Gibbs free energy of formation and the impingement rates of the two constituents. The resulting model describes the binary cluster size distribution along a line in n1,n2-space. The solution of the binary general dynamic equation is compared with the solution of formally exact binary Becker-Döring equations for a typical nucleation pulse experiment. The results show good agreement for the cluster composition and size and the integral properties of the size distribution.

  14. Raindrop Size Distribution Measurements in Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Tokay, A.; Bashor, P. G.; Habib, E.; Kasparis, T. C.

    2006-12-01

    Measurements of the raindrop size distribution (RSD) have been collected in tropical cyclones and hurricanes with an impact type disdrometer during the past three Atlantic hurricane seasons. The measurements were taken at Wallops Island, Virginia, Lafayette, Louisiana, and Orlando, Florida. The RSDs from the remnants of tropical cyclones or hurricanes at 40 dBZ agreed well with each other where the mean mass diameter was 1.65-1.7 mm, and the total concentration had a range of 600 to 800 drops/m3. Assuming the normalized gamma size distribution, the shape parameter will be 5-8 to satisfy the observed rain rate of 18-20 mm/hr. If the observations were taken during the extratropical phase of the storm where the tropical cyclone merges with a frontal system, the composite spectra at 40 dBZ include more large drops and less small to mid-size drops, typical for continental thunderstorms. Thus, the mean mass diameter was larger, while total concentration, and rain rate was less in extratropical cyclones than in tropical cyclones.

  15. Particle size distribution of indoor aerosol sources

    SciTech Connect

    Shah, K.B.

    1990-10-24

    As concern about Indoor Air Quality (IAQ) has grown in recent years, it has become necessary to determine the nature of particles produced by different indoor aerosol sources and the typical concentration that these sources tend to produce. These data are important in predicting the dose of particles to people exposed to these sources and it will also enable us to take effective mitigation procedures. Further, it will also help in designing appropriate air cleaners. A new state of the art technique, DMPS (Differential Mobility Particle Sizer) System is used to determine the particle size distributions of a number of sources. This system employs the electrical mobility characteristics of these particles and is very effective in the 0.01--1.0 {mu}m size range. A modified system that can measure particle sizes in the lower size range down to 3 nm was also used. Experimental results for various aerosol sources is presented in the ensuing chapters. 37 refs., 20 figs., 2 tabs.

  16. Particle Size Distribution in Aluminum Manufacturing Facilities

    PubMed Central

    Liu, Sa; Noth, Elizabeth M.; Dixon-Ernst, Christine; Eisen, Ellen A.; Cullen, Mark R.; Hammond, S. Katharine

    2015-01-01

    As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminum industry, area particle samples were collected in production facilities to assess instrument reliability and particle size distribution at different process areas. Personal modular impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used. The coefficient of variation (CV) of co-located samples was used to evaluate the reproducibility of the samplers. PM2.5 measured by PMI was compared to PM2.5 calculated from MiniMOUDI data. Mass median aerodynamic diameter (MMAD) and concentrations of sub-micrometer (PM1.0) and quasi-ultrafine (PM0.56) particles were evaluated to characterize particle size distribution. Most of CVs were less than 30%. The slope of the linear regression of PMI_PM2.5 versus MiniMOUDI_PM2.5 was 1.03 mg/m3 per mg/m3 (± 0.05), with correlation coefficient of 0.97 (± 0.01). Particle size distribution varied substantively in smelters, whereas it was less variable in fabrication units with significantly smaller MMADs (arithmetic mean of MMADs: 2.59 μm in smelters vs. 1.31 μm in fabrication units, p = 0.001). Although the total particle concentration was more than two times higher in the smelters than in the fabrication units, the fraction of PM10 which was PM1.0 or PM0.56 was significantly lower in the smelters than in the fabrication units (p < 0.001). Consequently, the concentrations of sub-micrometer and quasi-ultrafine particles were similar in these two types of facilities. It would appear, studies evaluating ultrafine particle exposure in aluminum industry should focus on not only the smelters, but also the fabrication facilities. PMID:26478760

  17. Particle Size Distribution in Aluminum Manufacturing Facilities.

    PubMed

    Liu, Sa; Noth, Elizabeth M; Dixon-Ernst, Christine; Eisen, Ellen A; Cullen, Mark R; Hammond, S Katharine

    2014-10-01

    As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminum industry, area particle samples were collected in production facilities to assess instrument reliability and particle size distribution at different process areas. Personal modular impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used. The coefficient of variation (CV) of co-located samples was used to evaluate the reproducibility of the samplers. PM2.5 measured by PMI was compared to PM2.5 calculated from MiniMOUDI data. Mass median aerodynamic diameter (MMAD) and concentrations of sub-micrometer (PM1.0) and quasi-ultrafine (PM0.56) particles were evaluated to characterize particle size distribution. Most of CVs were less than 30%. The slope of the linear regression of PMI_PM2.5 versus MiniMOUDI_PM2.5 was 1.03 mg/m(3) per mg/m(3) (± 0.05), with correlation coefficient of 0.97 (± 0.01). Particle size distribution varied substantively in smelters, whereas it was less variable in fabrication units with significantly smaller MMADs (arithmetic mean of MMADs: 2.59 μm in smelters vs. 1.31 μm in fabrication units, p = 0.001). Although the total particle concentration was more than two times higher in the smelters than in the fabrication units, the fraction of PM10 which was PM1.0 or PM0.56 was significantly lower in the smelters than in the fabrication units (p < 0.001). Consequently, the concentrations of sub-micrometer and quasi-ultrafine particles were similar in these two types of facilities. It would appear, studies evaluating ultrafine particle exposure in aluminum industry should focus on not only the smelters, but also the fabrication facilities.

  18. Aerosol Size Distribution in the marine regions

    NASA Astrophysics Data System (ADS)

    Markuszewski, Piotr; Petelski, Tomasz; Zielinski, Tymon; Pakszys, Paulina; Strzalkowska, Agata; Makuch, Przemyslaw; Kowalczyk, Jakub

    2014-05-01

    We would like to present the data obtained during the regular research cruises of the S/Y Oceania over a period of time between 2009 - 2012. The Baltic Sea is a very interesting polygon for aerosol measurements, however, also difficult due to the fact that mostly cases of a mixture of continental and marine aerosols are observed. It is possible to measure clear marine aerosol, but also advections of dust from southern Europe or even Africa. This variability of data allows to compare different conditions. The data is also compared with our measurements from the Arctic Seas, which have been made during the ARctic EXperiment (AREX). The Arctic Seas are very suitable for marine aerosol investigations since continental advections of aerosols are far less frequent than in other European sea regions. The aerosol size distribution was measured using the TSI Laser Aerosol Spectrometer model 3340 (99 channels, measurement range 0.09 μm to 7 μm), condensation particle counter (range 0.01 μm to 3 μm) and laser particle counter PMS CSASP-100-HV-SP (range 0.5 μm to 47 μm in 45 channels). Studies of marine aerosol production and transport are important for many Earth sciences such as cloud physics, atmospheric optics, environmental pollution studies and interaction between ocean and atmosphere. All equipment was placed on one of the masts of S/Y Oceania. Measurements using the laser aerosol spectrometer and condensation particle counter were made on one level (8 meters above sea level). Measurements with the laser particle counter were performed at five different levels above the sea level (8, 11, 14, 17 and 20 m). Based on aerosol size distribution the parameterizations with a Log-Normal and a Power-Law distributions were made. The aerosol source functions, characteristic for the region were also determined. Additionally, poor precision of the sea spray emission determination was confirmed while using only the aerosol concentration data. The emission of sea spray depends

  19. Formation and size distribution of self-assembled vesicles.

    PubMed

    Huang, Changjin; Quinn, David; Sadovsky, Yoel; Suresh, Subra; Hsia, K Jimmy

    2017-03-14

    When detergents and phospholipid membranes are dispersed in aqueous solutions, they tend to self-assemble into vesicles of various shapes and sizes by virtue of their hydrophobic and hydrophilic segments. A clearer understanding of such vesiculation processes holds promise for better elucidation of human physiology and disease, and paves the way to improved diagnostics, drug development, and drug delivery. Here we present a detailed analysis of the energetics and thermodynamics of vesiculation by recourse to nonlinear elasticity, taking into account large deformation that may arise during the vesiculation process. The effects of membrane size, spontaneous curvature, and membrane stiffness on vesiculation and vesicle size distribution were investigated, and the critical size for vesicle formation was determined and found to compare favorably with available experimental evidence. Our analysis also showed that the critical membrane size for spontaneous vesiculation was correlated with membrane thickness, and further illustrated how the combined effects of membrane thickness and physical properties influenced the size, shape, and distribution of vesicles. These findings shed light on the formation of physiological extracellular vesicles, such as exosomes. The findings also suggest pathways for manipulating the size, shape, distribution, and physical properties of synthetic vesicles, with potential applications in vesicle physiology, the pathobiology of cancer and other diseases, diagnostics using in vivo liquid biopsy, and drug delivery methods.

  20. Formation and size distribution of self-assembled vesicles

    PubMed Central

    Huang, Changjin; Quinn, David; Suresh, Subra

    2017-01-01

    When detergents and phospholipid membranes are dispersed in aqueous solutions, they tend to self-assemble into vesicles of various shapes and sizes by virtue of their hydrophobic and hydrophilic segments. A clearer understanding of such vesiculation processes holds promise for better elucidation of human physiology and disease, and paves the way to improved diagnostics, drug development, and drug delivery. Here we present a detailed analysis of the energetics and thermodynamics of vesiculation by recourse to nonlinear elasticity, taking into account large deformation that may arise during the vesiculation process. The effects of membrane size, spontaneous curvature, and membrane stiffness on vesiculation and vesicle size distribution were investigated, and the critical size for vesicle formation was determined and found to compare favorably with available experimental evidence. Our analysis also showed that the critical membrane size for spontaneous vesiculation was correlated with membrane thickness, and further illustrated how the combined effects of membrane thickness and physical properties influenced the size, shape, and distribution of vesicles. These findings shed light on the formation of physiological extracellular vesicles, such as exosomes. The findings also suggest pathways for manipulating the size, shape, distribution, and physical properties of synthetic vesicles, with potential applications in vesicle physiology, the pathobiology of cancer and other diseases, diagnostics using in vivo liquid biopsy, and drug delivery methods. PMID:28265065

  1. Particle size distribution from a GTL engine.

    PubMed

    Li, Xinling; Huang, Zhen; Wang, Jiasong; Zhang, Wugao

    2007-09-01

    Measurements of exhaust particle number concentration and size distribution from an engine fueled with GTL at different engine loads and speeds were carried out by using a two-stage dilution system. The results for GTL were compared with those from the original engine fueled with diesel. The fuel composition and engine operation condition had significant effects on the exhaust particle size distribution, the total exhaust particle number and volume concentrations. For both fuels, the load had no significant influence on the total exhaust particle number concentration at middle speed, while the total exhaust particle number concentration increased with the increase of the load at high speed. At 1400 rpm and 2200 rpm, the total exhaust particle volume concentration increased as the load increased for both fuels. GTL was found to be a "cleaner" fuel. Compared with diesel, under the same operation conditions, the total exhaust particle number concentrations decreased 18-92%, and the total exhaust particle volume concentrations for GTL decreased 21-59%.

  2. Environmental DNA particle size distribution from Brook Trout (Salvelinus fontinalis)

    Treesearch

    Taylor M. Wilcox; Kevin S. McKelvey; Michael K. Young; Winsor H. Lowe; Michael K. Schwartz

    2015-01-01

    Environmental DNA (eDNA) sampling has become a widespread approach for detecting aquatic animals with high potential for improving conservation biology. However, little research has been done to determine the size of particles targeted by eDNA surveys. In this study, we conduct particle distribution analysis of eDNA from a captive Brook Trout (Salvelinus fontinalis) in...

  3. Modeling The Size Distribution Of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Albers, Nicole; Esposito, L. W.

    2007-10-01

    Spatial structures such as density and bending waves, self-gravity and moonlet wakes are among the better known pieces in the puzzle of the formation and evolution of Saturn's main rings. But also the actual sizes of ring particles are very important to understand the long-term behavior or the system. The Cassini mission is continuing to provide a wealth of new observations. Among those are the transient features, bright clumps, and brightness fluctuations in the rather mysterious F ring that are partially attributed to a population of moonlets hidden well within the bright core of the structure. Detections of opaque features during stellar occultations of the UVIS and VIMS instruments strongly support this idea. Further, the discovery of embedded moonlets in Saturn's A ring raises questions about the origin of these objects; not to forget about the km-sized moons, Pan and Daphnis, orbiting within the A ring. Are they remnants of a shattered moon or is it possible to accrete these objects from the surrounding ring material? Currently, the theory still lags behind the observations. Here, we employ a generalized kinetic approach aiming at the long-term evolution of the size distribution that cannot be achieved by current N-body simulations and discuss its implications for the evolution and origin of Saturn's rings.

  4. Synthesis of MSnO{sub 3} (M = Ba, Sr) nanoparticles by reverse micelle method and particle size distribution analysis by whole powder pattern modeling

    SciTech Connect

    Ahmed, Jahangeer; Blakely, Colin K.; Bruno, Shaun R.; Poltavets, Viktor V.

    2012-09-15

    Highlights: ► BaSnO{sub 3} and SrSnO{sub 3} nanoparticles synthesized using the reverse micelle method. ► Particle size and size distribution studied by whole powder pattern modeling. ► Nanoparticles are of optimal size for investigation in dye-sensitized solar cells. -- Abstract: Light-to-electricity conversion efficiency in dye-sensitized solar cells critically depends not only on the dye molecule, semiconducting material and redox shuttle selection but also on the particle size and particle size distribution of the semiconducting photoanode. In this study, nanocrystalline BaSnO{sub 3} and SrSnO{sub 3} particles have been synthesized using the microemulsion method. Particle size distribution was studied by whole powder pattern modeling which confirmed narrow particle size distribution with an average size of 18.4 ± 8.3 nm for SrSnO{sub 3} and 15.8 ± 4.2 nm for BaSnO{sub 3}. These values are in close agreement with results of transmission electron microscopy. The prepared materials have optimal microstructure for successive investigation in dye-sensitized solar cells.

  5. A Comparison of the Performance of Efficient Data Analysis Versus Fine Particle Dose as Metrics for the Quality Control of Aerodynamic Particle Size Distributions of Orally Inhaled Pharmaceuticals.

    PubMed

    Tougas, Terrence P; Goodey, Adrian P; Hardwell, Gareth; Mitchell, Jolyon; Lyapustina, Svetlana

    2017-02-01

    The performance of two quality control (QC) tests for aerodynamic particle size distributions (APSD) of orally inhaled drug products (OIPs) is compared. One of the tests is based on the fine particle dose (FPD) metric currently expected by the European regulators. The other test, called efficient data analysis (EDA), uses the ratio of large particle mass to small particle mass (LPM/SPM), along with impactor sized mass (ISM), to detect changes in APSD for QC purposes. The comparison is based on analysis of APSD data from four products (two different pressurized metered dose inhalers (MDIs) and two dry powder inhalers (DPIs)). It is demonstrated that in each case, EDA is able to detect shifts and abnormalities that FPD misses. The lack of sensitivity on the part of FPD is due to its "aggregate" nature, since FPD is a univariate measure of all particles less than about 5 μm aerodynamic diameter, and shifts or changes within the range encompassed by this metric may go undetected. EDA is thus shown to be superior to FPD for routine control of OIP quality. This finding augments previously reported superiority of EDA compared with impactor stage groupings (favored by US regulators) for incorrect rejections (type I errors) when incorrect acceptances (type II errors) were adjusted to the same probability for both approaches. EDA is therefore proposed as a method of choice for routine quality control of OIPs in both European and US regulatory environments.

  6. Particle size distributions and the vertical distribution of suspended matter in the upwelling region off Oregon

    NASA Technical Reports Server (NTRS)

    Kitchen, J. C.

    1977-01-01

    Various methods of presenting and mathematically describing particle size distribution are explained and evaluated. The hyperbolic distribution is found to be the most practical but the more complex characteristic vector analysis is the most sensitive to changes in the shape of the particle size distributions. A method for determining onshore-offshore flow patterns from the distribution of particulates was presented. A numerical model of the vertical structure of two size classes of particles was developed. The results show a close similarity to the observed distributions but overestimate the particle concentration by forty percent. This was attributed to ignoring grazing by zooplankton. Sensivity analyses showed the size preference was most responsive to the maximum specific growth rates and nutrient half saturation constants. The verical structure was highly dependent on the eddy diffusivity followed closely by the growth terms.

  7. A Monte-Carlo simulation analysis for evaluating the severity distribution functions (SDFs) calibration methodology and determining the minimum sample-size requirements.

    PubMed

    Shirazi, Mohammadali; Reddy Geedipally, Srinivas; Lord, Dominique

    2017-01-01

    Severity distribution functions (SDFs) are used in highway safety to estimate the severity of crashes and conduct different types of safety evaluations and analyses. Developing a new SDF is a difficult task and demands significant time and resources. To simplify the process, the Highway Safety Manual (HSM) has started to document SDF models for different types of facilities. As such, SDF models have recently been introduced for freeway and ramps in HSM addendum. However, since these functions or models are fitted and validated using data from a few selected number of states, they are required to be calibrated to the local conditions when applied to a new jurisdiction. The HSM provides a methodology to calibrate the models through a scalar calibration factor. However, the proposed methodology to calibrate SDFs was never validated through research. Furthermore, there are no concrete guidelines to select a reliable sample size. Using extensive simulation, this paper documents an analysis that examined the bias between the 'true' and 'estimated' calibration factors. It was indicated that as the value of the true calibration factor deviates further away from '1', more bias is observed between the 'true' and 'estimated' calibration factors. In addition, simulation studies were performed to determine the calibration sample size for various conditions. It was found that, as the average of the coefficient of variation (CV) of the 'KAB' and 'C' crashes increases, the analyst needs to collect a larger sample size to calibrate SDF models. Taking this observation into account, sample-size guidelines are proposed based on the average CV of crash severities that are used for the calibration process.

  8. The Italian primary school-size distribution and the city-size: a complex nexus

    PubMed Central

    Belmonte, Alessandro; Di Clemente, Riccardo; Buldyrev, Sergey V.

    2014-01-01

    We characterize the statistical law according to which Italian primary school-size distributes. We find that the school-size can be approximated by a log-normal distribution, with a fat lower tail that collects a large number of very small schools. The upper tail of the school-size distribution decreases exponentially and the growth rates are distributed with a Laplace PDF. These distributions are similar to those observed for firms and are consistent with a Bose-Einstein preferential attachment process. The body of the distribution features a bimodal shape suggesting some source of heterogeneity in the school organization that we uncover by an in-depth analysis of the relation between schools-size and city-size. We propose a novel cluster methodology and a new spatial interaction approach among schools which outline the variety of policies implemented in Italy. Different regional policies are also discussed shedding lights on the relation between policy and geographical features. PMID:24954714

  9. The Size Distribution of Cometary Nuclei

    NASA Astrophysics Data System (ADS)

    Weissman, P. R.; Lowry, S. C.

    2001-11-01

    We are conducting a program of ground-based CCD photometry of distant cometary nuclei, in order to estimate their sizes, shapes, rotation periods and axial ratios. We have combined our data with that reported in the literature by other observers to obtain an estimate of the size distribution of observed Jupiter-family and Halley-type comets. The catalog consists of 79 measurements of 52 JF and HT comets using a variety of techniques, including CCD photometry, IR photometry, and HST imaging. The data has been normalized to an assumed albedo of 0.04 except in cases where the albedo was directly measured. We find that the cumulative number of comets at or larger than a given radius can be described by a power law function with a slope of --1.40 +/- 0.03. This corresponds to a slope of --0.28 +/- 0.01 for the cumulative luminosity function, close to the slope of --0.32 +/- 0.02 found by Lowry (2001), derived from a homogeneously reduced CCD survey of distant JF comets. Both values are considerably less than the slope of --0.53 +/- 0.05 found by Fernández et al. (1999). This inconsistency is most likely attributed to the inhomogeneous nature of the Fernández et al. dataset, and the inclusion of active comets within their sample. Typical values of the CLF slope for Kuiper belt objects are --0.64 to --0.69 (Gladman et al. 2001; Trujillo et al. 2001). The shallower slope of the JF and HT comets, which are considerably smaller than the measured Kuiper belt objects, may be due to intrinsic differences in the KBO size distribution at the different size ranges (Weissman & Levison 1998) or to the physical evolution of JF and HT comets as they lose mass through sublimation and fragmentation (Lowry 2001). This work was supported by the NASA Planetary Astronomy and Planetary Geology & Geophysics Programs. Support from the National Research Council is also gratefully acknowledged.

  10. Mass size distribution of particle-bound water

    NASA Astrophysics Data System (ADS)

    Canepari, S.; Simonetti, G.; Perrino, C.

    2017-09-01

    The thermal-ramp Karl-Fisher method (tr-KF) for the determination of PM-bound water has been applied to size-segregated PM samples collected in areas subjected to different environmental conditions (protracted atmospheric stability, desert dust intrusion, urban atmosphere). This method, based on the use of a thermal ramp for the desorption of water from PM samples and the subsequent analysis by the coulometric KF technique, had been previously shown to differentiate water contributes retained with different strength and associated to different chemical components in the atmospheric aerosol. The application of the method to size-segregated samples has revealed that water showed a typical mass size distribution in each one of the three environmental situations that were taken into consideration. A very similar size distribution was shown by the chemical PM components that prevailed during each event: ammonium nitrate in the case of atmospheric stability, crustal species in the case of desert dust, road-dust components in the case of urban sites. The shape of the tr-KF curve varied according to the size of the collected particles. Considering the size ranges that better characterize the event (fine fraction for atmospheric stability, coarse fraction for dust intrusion, bi-modal distribution for urban dust), this shape is coherent with the typical tr-KF shape shown by water bound to the chemical species that predominate in the same PM size range (ammonium nitrate, crustal species, secondary/combustion species - road dust components).

  11. Aggregate size distribution of the soil loss

    NASA Astrophysics Data System (ADS)

    Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka; Józsa, Sándor; Szalai, Zoltán; Centeri, Csaba

    2016-04-01

    aggregate size distribution which is led to nutrient and organic matter redistribution is one of a key questions to improve erosion estimation. G. Jakab was supported by the János Bolyai fellowship of the HAS.

  12. Elemental composition and size distribution of particulates in Cleveland, Ohio

    NASA Technical Reports Server (NTRS)

    King, R. B.; Fordyce, J. S.; Neustadter, H. E.; Leibecki, H. F.

    1975-01-01

    Measurements were made of the elemental particle size distribution at five contrasting urban environments with different source-type distributions in Cleveland, Ohio. Air quality conditions ranged from normal to air pollution alert levels. A parallel network of high-volume cascade impactors (5-state) were used for simultaneous sampling on glass fiber surfaces for mass determinations and on Whatman-41 surfaces for elemental analysis by neutron activation for 25 elements. The elemental data are assessed in terms of distribution functions and interrelationships and are compared between locations as a function of resultant wind direction in an attempt to relate the findings to sources.

  13. Power laws, discontinuities and regional city size distributions

    USGS Publications Warehouse

    Garmestani, A.S.; Allen, C.R.; Gallagher, C.M.

    2008-01-01

    Urban systems are manifestations of human adaptation to the natural environment. City size distributions are the expression of hierarchical processes acting upon urban systems. In this paper, we test the entire city size distributions for the southeastern and southwestern United States (1990), as well as the size classes in these regions for power law behavior. We interpret the differences in the size of the regional city size distributions as the manifestation of variable growth dynamics dependent upon city size. Size classes in the city size distributions are snapshots of stable states within urban systems in flux. ?? 2008.

  14. Parameterizing Size Distribution in Ice Clouds

    SciTech Connect

    DeSlover, Daniel; Mitchell, David L.

    2009-09-25

    PARAMETERIZING SIZE DISTRIBUTIONS IN ICE CLOUDS David L. Mitchell and Daniel H. DeSlover ABSTRACT An outstanding problem that contributes considerable uncertainty to Global Climate Model (GCM) predictions of future climate is the characterization of ice particle sizes in cirrus clouds. Recent parameterizations of ice cloud effective diameter differ by a factor of three, which, for overcast conditions, often translate to changes in outgoing longwave radiation (OLR) of 55 W m-2 or more. Much of this uncertainty in cirrus particle sizes is related to the problem of ice particle shattering during in situ sampling of the ice particle size distribution (PSD). Ice particles often shatter into many smaller ice fragments upon collision with the rim of the probe inlet tube. These small ice artifacts are counted as real ice crystals, resulting in anomalously high concentrations of small ice crystals (D < 100 µm) and underestimates of the mean and effective size of the PSD. Half of the cirrus cloud optical depth calculated from these in situ measurements can be due to this shattering phenomenon. Another challenge is the determination of ice and liquid water amounts in mixed phase clouds. Mixed phase clouds in the Arctic contain mostly liquid water, and the presence of ice is important for determining their lifecycle. Colder high clouds between -20 and -36 oC may also be mixed phase but in this case their condensate is mostly ice with low levels of liquid water. Rather than affecting their lifecycle, the presence of liquid dramatically affects the cloud optical properties, which affects cloud-climate feedback processes in GCMs. This project has made advancements in solving both of these problems. Regarding the first problem, PSD in ice clouds are uncertain due to the inability to reliably measure the concentrations of the smallest crystals (D < 100 µm), known as the “small mode”. Rather than using in situ probe measurements aboard aircraft, we employed a treatment of ice

  15. APSAS; an Automated Particle Size Analysis System

    USGS Publications Warehouse

    Poppe, Lawrence J.; Eliason, A.H.; Fredericks, J.J.

    1985-01-01

    The Automated Particle Size Analysis System integrates a settling tube and an electroresistance multichannel particle-size analyzer (Coulter Counter) with a Pro-Comp/gg microcomputer and a Hewlett Packard 2100 MX(HP 2100 MX) minicomputer. This system and its associated software digitize the raw sediment grain-size data, combine the coarse- and fine-fraction data into complete grain-size distributions, perform method of moments and inclusive graphics statistics, verbally classify the sediment, generate histogram and cumulative frequency plots, and transfer the results into a data-retrieval system. This system saves time and labor and affords greater reliability, resolution, and reproducibility than conventional methods do.

  16. Gas accumulations and their association with particle size distribution patterns in the Ría de Arousa seabed (Galicia, NW Spain): an application of discriminant analysis

    NASA Astrophysics Data System (ADS)

    Diez, R.; García-Gil, S.; Durán, R.; Vilas, F.

    2007-06-01

    Gassy sediments in the Ría de Arousa are preferentially distributed in areas of muddy seabed sediments. The close relationship between seabed sediment parameters and gas distribution is here studied in detail to establish better constraints on the presence of gas. Discriminant analysis was applied to the textural and compositional characteristics of 303 seabed sediment samples to classify gas-related and gas-free areas in the Ría de Arousa. The parameters considered in the classification were: particle size data (percentages of clay, silt, sand and gravel), the total inorganic carbon and the total organic carbon contents of the samples. The samples were initially classified in two groups according to the presence or absence of acoustic turbidity in the seismic profiles, shallower than 150 cm below seabed. Of the total known cases, 85.5% were correctly classified using these variables. Applying the Wilks’ lambda criterion, the most influential textural discriminating variables were the percentage of clay and the percentage of coarse fraction (gravel and sand) in the sediment sample. Discriminant analysis has achieved good differentiation between gas-related and gas-free sediments using near-seabed sediment information. The application of the discriminant method has enabled the estimation of the total area covered by gassy sediments in the Ría de Arousa. The area calculated based on the seismic data (30 km2) is a minimum estimate that is constrained by the limits of the existing seismic data. Based on the sediment information obtained from seabed samples, the statistical method estimates a total area of gassy sediments of 39 km2. The new gassy areas recognized are located around the gas field at the inner ría, and the gas field west of Arousa Island, which increase in area by 8.3 and 0.4 km2 respectively.

  17. Determination of atmospheric particle size distribution from forward scattering data.

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.

    1973-01-01

    Description of an analytic method of reconstructing the particle size distribution of atmospheric aerosols when no a priori information is available regarding the refractive index of the particles, the analytic form of the distribution, the size range, and the size extremal values. The method applies in principle to angle-dependent scattering data at a fixed wave number, or to wave-number-dependent scattering data at a fixed angle, or to a combination of the two. Some results of an angular scan study of the aureole are presented to illustrate the effectiveness of the method. In conclusion, an analysis is made of the efficiency and accuracy of the method, the uniqueness of the inverse solutions, and the stability of the method relative to experimental noise.

  18. Quantifying the PAH Size Distribution in H II-Regions

    NASA Astrophysics Data System (ADS)

    Allamandola, Louis

    distribution in the selected H II-regions. Because the analysis is based on the spectra of actual PAH molecules, quantitative size information is intrinsic to this analysis. This makes it possible to determine the sizes of the PAHs that contribute to the spectrum and aggregate them into specific PAH size bins. With this information, other observational proxies (such as the 7.6/11.2 µm PAH band strength ratio) that have been suggested as PAH size indicators will also be tested. The long term goal of this proposal is to provide the astronomical community with tools and calibration charts that are straightforward to use for analyzing the PAH spectra of any object emitting the PAH features obtained by JWST and quantitatively determine the PAH size distribution in those objects. JWST is the first telescope that will capture the complete midinfrared PAH spectrum with fully resolved features, through a single aperture, and along narrow, single, lines-of-sight. In short, the work proposed here represents an important step in enabling the PAH model to reach its full potential as a diagnostic of the physical and chemical conditions in the astronomical objects that span the Universe.

  19. Particle size distribution: a key factor in estimating powder dustiness.

    PubMed

    López-Lilao, Ana; Sanfélix, Forner Vicenta; Mallol, Gasch Gustavo; Monfort, Gimeno Eliseo

    2017-08-01

    ASTRACT A wide variety of raw materials, involving more than twenty samples of quartzes, feldspars, nephelines, carbonates, dolomites, sands, zircons, and alumina, were selected and characterised. Dustiness, i.e. a materials' tendency to generate dust on handling, was determined using the continuous drop method. These raw materials were selected to encompass a wide range of particle sizes (1.6-294 µm) and true densities (2650-4680 kg/m(3)). The dustiness of the raw materials, i.e. their tendency to generate dust on handling, was determined using the continuous drop method. The influence of some key material parameters (particle size distribution, flowability and specific surface area) on dustiness was assessed. In this regard, dustiness was found to be significantly affected by particle size distribution. Data analysis enabled development of a model for predicting the dustiness of the studied materials, assuming that dustiness depended on the particle fraction susceptible to emission and on the bulk material's susceptibility to release these particles. On the one hand, the developed model allows the dustiness mechanisms to be better understood. In this regard, it may be noted that relative emission increased with mean particle size. However, this did not necessarily imply that dustiness did, because dustiness also depended on the fraction of particles susceptible to be emitted. On the other hand, the developed model enables dustiness to be estimated using just the particle size distribution data. The quality of the fits was quite good and the fact that only particle size distribution data are needed facilitates industrial application, since these data are usually known by raw materials managers, thus making additional tests unnecessary. This model may therefore be deemed a key tool in drawing up efficient preventive and/or corrective measures to reduce dust emissions during bulk powder processing, both inside and outside industrial facilities. It is recommended

  20. Distributional shifts in size structure of phytoplankton community

    NASA Astrophysics Data System (ADS)

    Waga, H.; Hirawake, T.; Fujiwara, A.; Nishino, S.; Kikuchi, T.; Suzuki, K.; Takao, S.

    2015-12-01

    Increased understanding on how marine species shift their distribution is required for effective conservation of fishery resources under climate change. Previous studies have often predicted distributional shifts of fish using satellite derived sea surface temperature (SST). However, SST may not fully represent the changes in species distribution through food web structure and as such this remains an open issue due to lack of ecological perspective on energy transfer process in the earlier studies. One of the most important factors in ecosystem is composition of phytoplankton community, and its size structure determines energy flow efficiency from base to higher trophic levels. To elucidate spatiotemporal variation in phytoplankton size structure, chlorophyll-a size distribution (CSD) algorithm was developed using spectral variance of phytoplankton absorption coefficient through principal component analysis. Slope of CSD (CSD slope) indicates size structure of phytoplankton community where, strong and weak magnitudes of CSD slope indicate smaller and larger phytoplankton structure, respectively. Shifts in CSD slope and SST were derived as the ratio of temporal trend over the 12-year period (2003-2014) to 2-dimensional spatial gradient and the resulting global median velocity of CSD slope and SST were 0.361 and 0.733 km year-1, respectively. In addition, the velocity of CSD slope monotonically increases with increasing latitude, while relatively complex latitudinal pattern for SST emerged. Moreover, angle of shifts suggest that species are required to shift their distribution toward not limited to simple pole-ward migration, and some regions exhibit opposite direction between the velocity of CSD slope and SST. These findings further imply that combined phytoplankton size structure and SST may contribute for more accurate prediction of species distribution shifts relative to existing studies which only considering variations in thermal niches.

  1. Soil signature simulation of complex mixtures and particle size distributions

    NASA Astrophysics Data System (ADS)

    Carson, Tyler; Bachmann, Charles M.; Salvaggio, Carl

    2015-09-01

    Soil reflectance signatures were modeled using the digital imaging and remote sensing image generation model and Blender three-dimensional (3-D) graphic design software. Using these tools, the geometry, radiometry, and chemistry of quartz and magnetite were exploited to model the presence of particle size and porosity effects in the visible and the shortwave infrared spectrum. Using the physics engines within the Blender 3-D graphic design software, physical representations of granular soil scenes were created. Each scene characterized a specific particle distribution and density. Chemical and optical properties of pure quartz and magnetite were assigned to particles in the scene based on particle size. This work presents a model to describe an observed phase-angle dependence of beach sand density. Bidirectional reflectance signatures were simulated for targets of varying size distribution and density. This model provides validation for a phenomenological trade space between density and particle size distribution in complex, heterogeneous soil mixtures. It also confirms the suggestion that directional reflectance signatures can be defined by intimate mixtures that depend on pore spacing. The study demonstrated that by combining realistic target geometry and spectral measurements of pure quartz and magnetite, effects of soil particle size and density could be modeled without functional data fitting or rigorous analysis of material dynamics. This research does not use traditional function-based models for simulation. The combination of realistic geometry, physically viable particle structure, and first-principles ray-tracing enables the ability to represent signature changes that have been observed in experimental observations.

  2. A fractal-based approach to lake size-distributions

    NASA Astrophysics Data System (ADS)

    Seekell, David A.; Pace, Michael L.; Tranvik, Lars J.; Verpoorter, Charles

    2013-02-01

    The abundance and size distribution of lakes is critical to assessing the role of lakes in regional and global biogeochemical processes. Lakes are fractal but do not always conform to the power law size-distribution typically associated with fractal geographical features. Here, we evaluate the fractal geometry of lakes with the goal of explaining apparently inconsistent observations of power law and non-power law lake size-distributions. The power law size-distribution is a special case for lakes near the mean elevation. Lakes in flat regions are power law distributed, while lakes in mountainous regions deviate from power law distributions. Empirical analyses of lake size data sets from the Adirondack Mountains in New York and the flat island of Gotland in Sweden support this finding. Our approach provides a unifying framework for lake size-distributions, indicates that small lakes cannot dominate total lake surface area, and underscores the importance of regional hypsometry in influencing lake size-distributions.

  3. Collagen fibril arrangement and size distribution in monkey oral mucosa

    PubMed Central

    OTTANI, V.; FRANCHI, M.; DE PASQUALE, V.; LEONARDI, L.; MOROCUTTI, M.; RUGGERI, A.

    1998-01-01

    Collagen fibre organisation and fibril size were studied in the buccal gingival and hard palate mucosa of Macacus rhesus monkey. Light and electron microscopy analysis showed connective papillae exhibiting a similar inner structure in the different areas examined, but varying in distribution, shape and size. Moving from the deep to surface layers of the buccal gingival mucosa (free and attached portions), large collagen fibril bundles became smaller and progressively more wavy with decreasing collagen fibril diameter. This gradual diameter decrease did not occur in the hard palate mucosa (free portion, rugae and interrugal regions) where the fibril diameter remained constant. A link between collagen fibril diameter and mechanical function is discussed. PMID:9688498

  4. Evaluation of the Malvern optical particle monitor. [Volumetric size distribution

    SciTech Connect

    Anderson, R. J.; Johnson, E.

    1983-07-01

    The Malvern 2200/3300 Particle Sizer is a laser-based optical particle sizing device which utilizes the principle of Fraunhofer Diffraction as the means of particle size measurement. The instrument is designed to analyze particle sizes in the range of 1 to 1800 microns diameter through a selection of lenses for the receiving optics. It is not a single-particle counter but rather an ensemble averager over the distribution of particles present in the measuring volume. Through appropriate measurement techniques, the instrument can measure the volumetric size distribution of: solids in gas or liquid suspension; liquid droplets in gas or other immiscible liquids; and, gas bubbles in liquid. (Malvern Handbook, Version 1.5). This report details a limited laboratory evaluation of the Malvern system to determine its operational characteristics, limitations, and accuracy. This investigation focused on relatively small particles in the range of 5 to 150 microns. Primarily, well characterized particles of coal in a coal and water mixture were utilized, but a selection of naturally occurring, industrially generated, and standard samples (i.e., glass beads) wer also tested. The characteristic size parameter from the Malvern system for each of these samples was compared with the results of a Coulter particle counter (Model TA II) analysis to determine the size measurement accuracy. Most of the particulate samples were suspended in a liquid media (water or isoton, plus a dispersant) for the size characterization. Specifically, the investigations contained in this report fall into four categories: (a) Sample-to-lense distance and sample concentration studies, (b) studies testing the applicability to aerosols, (c) tests of the manufacturer supplied software, and (d) size measurement comparisons with the results of Coulter analysis. 5 references, 15 figures, 2 tables.

  5. Evaluation of Factors Affecting Size and Size Distribution of Chitosan-Electrosprayed Nanoparticles.

    PubMed

    Abyadeh, Morteza; Karimi Zarchi, Ali Akbar; Faramarzi, Mohammad Ali; Amani, Amir

    2017-01-01

    Size and size distribution of polymeric nanoparticles have important effect on their properties for pharmaceutical application. In this study, Chitosan nanoparticles were prepared by electrospray method (electrohydrodynamic atomization) and parameters that simultaneously affect size and/or size distribution of chitosan nanoparticles were optimized. Effect of formulation/processing three independent formulation/processing parameters, namely concentration, flow rate and applied voltage was investigated on particle size and size distribution of generated nanoparticles using a Box-Behnken experimental design. All the studied factors showed important effects on average size and size distribution of nanoparticles. A decrease in size and size distribution was obtainable with decreasing flow rate and concentration and increasing applied voltage. Eventually, a sample with minimum size and polydispersity was obtained with polymer concentration, flow rate and applied voltage values of 0.5 %w/v, 0.05 ml/hr and 15 kV, respectively. The experimentally prepared nanoparticles, expected having lowest size and size distribution values had a size of 105 nm, size distribution of 36 and Zeta potential of 59.3 mV. Results showed that optimum condition for production of chitosan nanoparticles with the minimum size and narrow size distribution was a minimum value for flow rate and highest value for applied voltage along with an optimum chitosan concentration.

  6. Size distributions and failure initiation of submarine and subaerial landslides

    NASA Astrophysics Data System (ADS)

    ten Brink, U. S.; Barkan, R.; Andrews, B. D.; Chaytor, J. D.

    2009-09-01

    affected by subaerial landslides is comparable to that calculated by slope stability analysis for submarine landslides. The area distribution of subaerial landslides from a single event may be determined by the size distribution of the morphology of the affected area, not by the initiation process.

  7. Size distributions and failure initiation of submarine and subaerial landslides

    USGS Publications Warehouse

    ten Brink, U.S.; Barkan, R.; Andrews, B.D.; Chaytor, J.D.

    2009-01-01

    affected by subaerial landslides is comparable to that calculated by slope stability analysis for submarine landslides. The area distribution of subaerial landslides from a single event may be determined by the size distribution of the morphology of the affected area, not by the initiation process. ?? 2009 Elsevier B.V.

  8. Effects of particle size distribution in thick film conductors

    NASA Technical Reports Server (NTRS)

    Vest, R. W.

    1983-01-01

    Studies of particle size distribution in thick film conductors are discussed. The distribution of particle sizes does have an effect on fired film density but the effect is not always positive. A proper distribution of sizes is necessary, and while the theoretical models can serve as guides to selecting this proper distribution, improved densities can be achieved by empirical variations from the predictions of the models.

  9. Improved Root Normal Size Distributions for Liquid Atomization

    DTIC Science & Technology

    2015-11-01

    Improved Root Normal Size Distributions for Liquid Atomization Distribution Statement A. Approved for public release; distribution is unlimited... Atomization Culbert B. Laney1 Engility Corp., 8211 Terminal Rd, Lorton, VA 22079 U.S.A. Abstract: This paper identifies two issues with traditional...root normal size distributions, which are commonly fitted to experimental results for liquid atomization and sprays. First, while root normal size

  10. High Sensitivity Method to Estimate Distribution of Hyaluronan Molecular Sizes in Small Biological Samples Using Gas-Phase Electrophoretic Mobility Molecular Analysis

    PubMed Central

    Do, Lan; Dahl, Christen P.; Kerje, Susanne; Hansell, Peter; Mörner, Stellan; Lindqvist, Ulla; Engström-Laurent, Anna; Larsson, Göran; Hellman, Urban

    2015-01-01

    Hyaluronan is a negatively charged polydisperse polysaccharide where both its size and tissue concentration play an important role in many physiological and pathological processes. The various functions of hyaluronan depend on its molecular size. Up to now, it has been difficult to study the role of hyaluronan in diseases with pathological changes in the extracellular matrix where availability is low or tissue samples are small. Difficulty to obtain large enough biopsies from human diseased tissue or tissue from animal models has also restricted the study of hyaluronan. In this paper, we demonstrate that gas-phase electrophoretic molecular mobility analyzer (GEMMA) can be used to estimate the distribution of hyaluronan molecular sizes in biological samples with a limited amount of hyaluronan. The low detection level of the GEMMA method allows for estimation of hyaluronan molecular sizes from different parts of small organs. Hence, the GEMMA method opens opportunity to attain a profile over the distribution of hyaluronan molecular sizes and estimate changes caused by disease or experimental conditions that has not been possible to obtain before. PMID:26448761

  11. Evolution of grain size distribution during deformation of superplastic materials

    SciTech Connect

    Lesuer, D.R.; Glaser, R.; Syn, C.K.

    1997-10-28

    Grain size distribution and its evolution during superplastic deformation has been studied for two materials- ultrahigh carbon steel, which has a two phase microstructure, and a copper alloy, which has a quasi-single phase microstructure. For both materials the distribution of initial grain size is very accurately represented by a lognormal throughout the deformation history. The evolution of the parameters characterizing the log normal distribution have also been studied and found to vary in a systematic manner results. Results can be used to specify the grain size distribution as a function of strain during superplastic deformation and thus should prove useful for computational studies in which grain size distribution is evaluated.

  12. The determination and optimization of (rutile) pigment particle size distributions

    NASA Technical Reports Server (NTRS)

    Richards, L. W.

    1972-01-01

    A light scattering particle size test which can be used with materials having a broad particle size distribution is described. This test is useful for pigments. The relation between the particle size distribution of a rutile pigment and its optical performance in a gray tint test at low pigment concentration is calculated and compared with experimental data.

  13. The determination and optimization of (rutile) pigment particle size distributions

    NASA Technical Reports Server (NTRS)

    Richards, L. W.

    1972-01-01

    A light scattering particle size test which can be used with materials having a broad particle size distribution is described. This test is useful for pigments. The relation between the particle size distribution of a rutile pigment and its optical performance in a gray tint test at low pigment concentration is calculated and compared with experimental data.

  14. Analysis of the vertical structure and size distribution of dust aerosols over the semi-arid region of the Loess Plateau in China

    NASA Astrophysics Data System (ADS)

    Zhou, B.; Zhang, L.; Cao, X.; Li, X.; Huang, J.; Shi, J.; Bi, J.

    2012-02-01

    Using measurements of dual-wavelength polarisation lidar, particle sizer, and nephelometer from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), the properties of dust aerosol extinction coefficient, optical depth, depolarisation ratio, colour ratio, size distribution, and concentration over the semi-arid region of the Loess Plateau in north-western China are analysed in a case study of dust storms from 16-18 March 2010. The results show that dust aerosols are distributed mostly within the lower layer (below 3.0 km), with the dust aerosol extinction coefficient ranging from 0.1 to 1.0 km-1. The average optical depth and depolarisation ratio are near 0.6 and 0.3, respectively, while the colour ratio ranges from 0.8 to 1.0. The mass size distribution of dust aerosols has two peaks at 0.7 μm and 5.0 μm, respectively, while the number size distribution of dust aerosols is log-normal with a maximum near 0.8 μm. Particles in the fine mode (r ≤ 2.5 μm) are predominant in the dust storm. Their number concentration decreases while those of particles in the moderate (2.5 μm < r ≤ 10.0 μm) and coarse (10.0 μm < r ≤ 20.0 μm) modes increase. Based on Mie theory and the number size distribution of the aerosol, the dust aerosol scattering coefficient and its variation with particle size are calculated and analysed. A fairly close correlation is found with that measured by the nephelometer, for which the correlation coefficients are 0.89 and 0.94, respectively, at 520 and 700 nm. It shows a Gaussian distribution of dust aerosol scattering coefficient against effective diameter, with a fitting coefficient of 0.96 and centre diameter of 5.5 μm. The contribution percentages of aerosol within fine, moderate, and coarse modes to dust aerosol scattering coefficient are 20.95%, 62.93%, and 16.12%, respectively, meaning that PM10 is a dominant factor in the dust aerosol scattering properties.

  15. Multifractal Characteristics of Bimodal Mercury Pore Size Distribution Curves

    NASA Astrophysics Data System (ADS)

    dos Santos Bonini, C.; Alves, M. C.; Paz González, A.

    2012-04-01

    Characterization of Hg pore size distribution (PSDs) curves by monofractal or multifractal analysis has been demonstrated to be an useful tool, which allows a better understanding of the organization of the soil pore space. There are also evidences that multiscale analysis of different segments found in bimodal pore size distributions measured by Hg intrusion can provide further valuable information. In this study we selected bimodal PSDs from samples taken from an experimental area in São Paulo state, Brazil, where a revegetation trial was set up over saprolitic material. The saprolite was left abandoned after decapitation of an Oxisol for building purposes. The field trial consisted of various treatments with different grass species and amendments. Pore size distribution of the sampled aggregates was measured in the equivalent diameter range from 0.005 to about 50 μm and it was characterized by a bimodal pattern, so that two compartments, i.e. 0.005 to 0.2 μm and 0.2 to 50 μm, could be distinguished. The multifractal theory was used to analyse both segments. The scaling properties of these two segments could be fitted reasonably well with multifractal models. Multifractal parameters obtained for equivalent diameters for the segments > 0.2 and < 0.2 μm showed great differences. For example, entropy dimension, D1, values from the segment 0.005-0.2 μm were always lower than those for the segment 0.2-50 μm form NDI , whereas the Hólder exponent of order zero, α0, were higher for the former segment. These results indicate the probability different degrees of heterogeneity within the Hg pore size distributions studied.

  16. Cloud object analysis of CERES Aqua observations of tropical and subtropical cloud regimes: Evolution of cloud object size distributions during the Madden-Julian Oscillation

    NASA Astrophysics Data System (ADS)

    Xu, Kuan-Man; Wong, Takmeng; Dong, Shengtao; Chen, Feng; Kato, Seiji; Taylor, Patrick C.

    2017-02-01

    In this study, we analyze cloud object data from the Aqua satellite between July 2006 and June 2010 that are matched with the real-time multivariate Madden-Julian Oscillation (MJO) index to examine the impact of MJO evolution on the evolutions of the size distributions of cloud object types. These types include deep convective (DC), cirrostratus, shallow cumulus, stratocumulus and overcast-stratus. A cloud object is a contiguous region of the earth with a single dominant cloud-system type. It is found that the cloud object size distributions of some phases depart greatly from the 8-phase combined distribution at large cloud-object diameters. The large-size group of cloud objects contributes to most of the temporal variations during the MJO evolution. For deep convective and cirrostratus cloud objects, there is a monotonic increase in both the number and footprint of large objects from the depressed to mature phases, which is attributed to the development and maturing of deep convection and anvils. The largest increase in the mean diameter during the mature phases that lasts to the early dissipating phase is related to growth of anvil clouds and is accompanied by moderate decreases in small-size objects. For shallow cumulus, the large objects decrease in number at the mature phases, but increase in number for both sizes before the mature phase. The opposite is true for the large overcast-stratus objects. The temporal evolution of large stratocumulus objects is similar to that of deep convective and cirrostratus object types except for peaking slightly earlier.

  17. How Sample Size Affects a Sampling Distribution

    ERIC Educational Resources Information Center

    Mulekar, Madhuri S.; Siegel, Murray H.

    2009-01-01

    If students are to understand inferential statistics successfully, they must have a profound understanding of the nature of the sampling distribution. Specifically, they must comprehend the determination of the expected value and standard error of a sampling distribution as well as the meaning of the central limit theorem. Many students in a high…

  18. How Sample Size Affects a Sampling Distribution

    ERIC Educational Resources Information Center

    Mulekar, Madhuri S.; Siegel, Murray H.

    2009-01-01

    If students are to understand inferential statistics successfully, they must have a profound understanding of the nature of the sampling distribution. Specifically, they must comprehend the determination of the expected value and standard error of a sampling distribution as well as the meaning of the central limit theorem. Many students in a high…

  19. Remote analysis of changes in the number of small thermokarst lakes and their distribution with respect to their sizes in the cryolithozone of Western Siberia, 2015

    NASA Astrophysics Data System (ADS)

    Polishchuk, Y. M.; Bryksina, N. A.; Polishchuk, V. Y.

    2015-12-01

    Regularities of changes in the number of thermokarst lakes in the cryolithozone of Western Siberia have been studied using multitemporal satellite images. The studies were conducted on 33 test sites selected in different landscape zones of the study area with the use of 134 cloud-free Landsat images obtained during warm months in the period from 1973 to 2013. It is shown that the total number of new lakes is significantly (almost 20 times) higher than the number of disappeared lakes. The area of newly formed thermokarst lakes is, on average, 22 times smaller than the size of disappearing lakes. Therefore, one can assume that the rapid growth in the number of small thermokarst lakes that is observed under the conditions of global warming will lead to an increase in methane emissions into the atmosphere in permafrost zones in the Arctic territories. Results of remote sensing of statistical distribution of small thermokarst lakes with respect to their sizes are given. The studies were performed on eight test sites selected in different permafrost zones of Western Siberia. The size of small lakes was determined according to QuickBird super-high resolution satellite images. It is shown that histograms of distribution of lakes with respect to their sizes allow their approximation by power and exponential functions, which can be used for modeling and predicting the dynamics of thermokarst methane emission in permafrost zones.

  20. Quantitative analysis of senile plaques in Alzheimer disease: observation of log-normal size distribution and molecular epidemiology of differences associated with apolipoprotein E genotype and trisomy 21 (Down syndrome).

    PubMed Central

    Hyman, B T; West, H L; Rebeck, G W; Buldyrev, S V; Mantegna, R N; Ukleja, M; Havlin, S; Stanley, H E

    1995-01-01

    The discovery that the epsilon 4 allele of the apolipoprotein E (apoE) gene is a putative risk factor for Alzheimer disease (AD) in the general population has highlighted the role of genetic influences in this extremely common and disabling illness. It has long been recognized that another genetic abnormality, trisomy 21 (Down syndrome), is associated with early and severe development of AD neuropathological lesions. It remains a challenge, however, to understand how these facts relate to the pathological changes in the brains of AD patients. We used computerized image analysis to examine the size distribution of one of the characteristic neuropathological lesions in AD, deposits of A beta peptide in senile plaques (SPs). Surprisingly, we find that a log-normal distribution fits the SP size distribution quite well, motivating a porous model of SP morphogenesis. We then analyzed SP size distribution curves in genotypically defined subgroups of AD patients. The data demonstrate that both apoE epsilon 4/AD and trisomy 21/AD lead to increased amyloid deposition, but by apparently different mechanisms. The size distribution curve is shifted toward larger plaques in trisomy 21/AD, probably reflecting increased A beta production. In apoE epsilon 4/AD, the size distribution is unchanged but the number of SP is increased compared to apoE epsilon 3, suggesting increased probability of SP initiation. These results demonstrate that subgroups of AD patients defined on the basis of molecular characteristics have quantitatively different neuropathological phenotypes. Images Fig. 2 Fig. 4 PMID:7724603

  1. Determination of the cumulus size distribution from LANDSAT pictures

    NASA Technical Reports Server (NTRS)

    Karg, E.; Mueller, H.; Quenzel, H.

    1983-01-01

    Varying insolation causes undesirable thermic stress to the receiver of a solar power plant. The rapid change of insolation depends on the size distribution of the clouds; in order to measure these changes, it is suitable to determine typical cumulus size distributions. For this purpose, LANDSAT-images are adequate. Several examples of cumulus size distributions will be presented and their effects on the operation of a solar power plant are discussed.

  2. How dense can one pack spheres of arbitrary size distribution?

    NASA Astrophysics Data System (ADS)

    Reis, S. D. S.; Araújo, N. A. M.; Andrade, J. S., Jr.; Herrmann, Hans J.

    2012-01-01

    We present the first systematic algorithm to estimate the maximum packing density of spheres when the grain sizes are drawn from an arbitrary size distribution. With an Apollonian filling rule, we implement our technique for disks in 2d and spheres in 3d. As expected, the densest packing is achieved with power-law size distributions. We also test the method on homogeneous and on empirical real distributions, and we propose a scheme to obtain experimentally accessible distributions of grain sizes with low porosity. Our method should be helpful in the development of ultra-strong ceramics and high-performance concrete.

  3. Observations of urban airborne particle number concentrations during rush-hour conditions: analysis of the number based size distributions and modal parameters.

    PubMed

    Lingard, Justin J N; Agus, Emily L; Young, David T; Andrews, Gordon E; Tomlin, Alison S

    2006-12-01

    A summertime study of the number concentration and the size distribution of combustion derived nanometre sized particles (termed nanoparticles) from diesel and spark-ignition (SI) engine emissions were made under rush-hour and free-flow traffic conditions at an urban roadside location in Leeds, UK in July 2003. The measured total particle number concentrations (N(TOTAL)) were of the order 1.8 x 10(4) to 3.4 x 10(4) cm(-3), and tended to follow the diurnal traffic flow patterns. The N(TOTAL) was dominated by particles < or =100 nm in diameter which accounted for between 89-93% of the measured particle number. By use of a log-normal fitting procedure, the modal parameters of the number based particle size distribution of urban airborne particulates were derived from the roadside measurements. Four component modes were identified. Two nucleation modes were found, with a smaller, more minor, mode composed principally of sub-11 nm particles, believed to be derived from particles formed from the nucleation of gaseous species in the atmosphere. A second mode, much larger in terms of number, was composed of particles within the size range of 10-20 nm. This second mode was believed to be principally derived from the condensation of the unburned fuel and lube oil (the solvent organic fraction or SOF) as it cooled on leaving the engine exhaust. Third and fourth modes were noted within the size ranges of 28-65 nm and 100-160 nm, respectively. The third mode was believed to be representative of internally mixed Aitken mode particles composed of a soot/ash core with an adsorbed layer of readily volatilisable material. The fourth mode was believed to be composed of chemically aged, secondary particles. The larger nucleation and Aitken modes accounted for between 80-90% of the measured N(TOTAL), and the particles in these modes were believed to be derived from SI and diesel engine emissions. The overall size distribution, particularly in modes II-IV, was observed to be strongly

  4. Analysis of long-term aerosol size distribution data from Jungfraujoch with emphasis on free tropospheric conditions, cloud influence, and air mass transport

    NASA Astrophysics Data System (ADS)

    Herrmann, Erik; Weingartner, Ernest; Henne, Stephan; Vuilleumier, Laurent; Bukowiecki, Nicolas; Steinbacher, Martin; Conen, Franz; Collaud Coen, Martine; Hammer, Emanuel; Jurányi, Zsofia; Baltensperger, Urs; Gysel, Martin

    2015-09-01

    Six years of aerosol size distribution measurements between 20 and 600 nm diameters and total aerosol concentration above 10 nm from March 2008 to February 2014 at the high-alpine site Jungfraujoch are presented. The size distribution was found to be typically bimodal with mode diameters and widths relatively stable throughout the year and the observation period. New particle formation was observed on 14.5% of all days without a seasonal preference. Particles typically grew only into the Aitken mode and did not reach cloud condensation nucleus (CCN) sizes on the time scale of several days. Growth of preexisting particles in the Aitken mode, on average, contributed very few CCN. We concluded that the dominant fraction of CCN at Jungfraujoch originated in the boundary layer. A number of approaches were used to distinguish free tropospheric (FT) conditions and episodes with planetary boundary layer (PBL) influence. In the absence of PBL injections, the concentration of particles larger than 90 nm (N90, roughly corresponding to the CCN concentration) reached a value ~40 cm-3 while PBL influence caused N90 concentrations of several hundred or even 1000 cm-3. Comparing three criteria for free tropospheric conditions, we found FT prevalence for 39% of the time with over 60% during winter and below 20% during summer. It is noteworthy that a simple criterion based on standard trace gas measurements appeared to outperform alternative approaches.

  5. Size resolved ultrafine particles emission model--a continues size distribution approach.

    PubMed

    Nikolova, Irina; Janssen, Stijn; Vrancken, Karl; Vos, Peter; Mishra, Vinit; Berghmans, Patrick

    2011-08-15

    A new parameterization for size resolved ultrafine particles (UFP) traffic emissions is proposed based on the results of PARTICULATES project (Samaras et al., 2005). It includes the emission factors from the Emission Inventory Guidebook (2006) (total number of particles, #/km/veh), the shape of the corresponding particle size distribution given in PARTICULATES and data for the traffic activity. The output of the model UFPEM (UltraFine Particle Emission Model) is a sum of continuous distributions of ultrafine particles emissions per vehicle type (passenger cars and heavy duty vehicles), fuel (petrol and diesel) and average speed representative for urban, rural and highway driving. The results from the parameterization are compared with measured total number of ultrafine particles and size distributions in a tunnel in Antwerp (Belgium). The measured UFP concentration over the entire campaign shows a close relation to the traffic activity. The modelled concentration is found to be lower than the measured in the campaign. The average emission factor from the measurement is 4.29E+14 #/km/veh whereas the calculated is around 30% lower. A comparison of emission factors with literature is done as well and in overall a good agreement is found. For the size distributions it is found that the measured distributions consist of three modes--Nucleation, Aitken and accumulation and most of the ultrafine particles belong to the Nucleation and the Aitken modes. The modelled Aitken mode (peak around 0.04-0.05 μm) is found in a good agreement both as amplitude of the peak and the number of particles whereas the modelled Nucleation mode is shifted to smaller diameters and the peak is much lower that the observed. Time scale analysis shows that at 300 m in the tunnel coagulation and deposition are slow and therefore neglected. The UFPEM emission model can be used as a source term in dispersion models. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Distributed analysis at LHCb

    NASA Astrophysics Data System (ADS)

    Williams, Mike; Egede, Ulrik; Paterson, Stuart; LHCb Collaboration

    2011-12-01

    The distributed analysis experience to date at LHCb has been positive: job success rates are high and wait times for high-priority jobs are low. LHCb users access the grid using the GANGA job-management package, while the LHCb virtual organization manages its resources using the DIRAC package. This clear division of labor has benefitted LHCb and its users greatly; it is a major reason why distributed analysis at LHCb has been so successful. The newly formed LHCb distributed analysis support team has also proved to be a success.

  7. Ejected Particle Size Distributions from Shocked Metal Surfaces

    DOE PAGES

    Schauer, M. M.; Buttler, W. T.; Frayer, D. K.; ...

    2017-04-12

    Here, we present size distributions for particles ejected from features machined onto the surface of shocked Sn targets. The functional form of the size distributions is assumed to be log-normal, and the characteristic parameters of the distribution are extracted from the measured angular distribution of light scattered from a laser beam incident on the ejected particles. We also found strong evidence for a bimodal distribution of particle sizes with smaller particles evolved from features machined into the target surface and larger particles being produced at the edges of these features.

  8. Pareto tails and lognormal body of US cities size distribution

    NASA Astrophysics Data System (ADS)

    Luckstead, Jeff; Devadoss, Stephen

    2017-01-01

    We consider a distribution, which consists of lower tail Pareto, lognormal body, and upper tail Pareto, to estimate the size distribution of all US cities. This distribution fits the data more accurately than a distribution that comprises of only lognormal and the upper tail Pareto.

  9. Changes of firm size distribution: The case of Korea

    NASA Astrophysics Data System (ADS)

    Kang, Sang Hoon; Jiang, Zhuhua; Cheong, Chongcheul; Yoon, Seong-Min

    2011-01-01

    In this paper, the distribution and inequality of firm sizes is evaluated for the Korean firms listed on the stock markets. Using the amount of sales, total assets, capital, and the number of employees, respectively, as a proxy for firm sizes, we find that the upper tail of the Korean firm size distribution can be described by power-law distributions rather than lognormal distributions. Then, we estimate the Zipf parameters of the firm sizes and assess the changes in the magnitude of the exponents. The results show that the calculated Zipf exponents over time increased prior to the financial crisis, but decreased after the crisis. This pattern implies that the degree of inequality in Korean firm sizes had severely deepened prior to the crisis, but lessened after the crisis. Overall, the distribution of Korean firm sizes changes over time, and Zipf’s law is not universal but does hold as a special case.

  10. Hierarchy, cities size distribution and Zipf's law

    NASA Astrophysics Data System (ADS)

    Semboloni, F.

    2008-06-01

    We show that a hierarchical cities structure can be generated by a self-organized process which grows with a bottom-up mechanism, and that the resulting distribution is power law. First we analytically prove that the power law distribution satisfies the balance between the offer of the city and the demand of its basin of attraction, and that the exponent in the Zipf's law corresponds to the multiplier linking the population of the central city to the population of its basin of attraction. Moreover, the corresponding hierarchical structure shows a variable spanning factor, and the population of the cities linked to the same city up in the hierarchy is variable as well. Second a stochastic dynamic spatial model is proposed, whose numerical results confirm the analytical findings. In this model, inhabitants minimize the transportation cost, so that the greater the importance of this cost, the more stable is the system in its microscopic aspect. After a comparison with the existent methods for the generation of a power law distribution, conclusions are drawn on the connection of hierarchical structure, and power law distribution, with the functioning of the system of cities.

  11. Evolution of Particle Size Distributions in Fragmentation Over Time

    NASA Astrophysics Data System (ADS)

    Charalambous, C. A.; Pike, W. T.

    2013-12-01

    We present a new model of fragmentation based on a probabilistic calculation of the repeated fracture of a particle population. The resulting continuous solution, which is in closed form, gives the evolution of fragmentation products from an initial block, through a scale-invariant power-law relationship to a final comminuted powder. Models for the fragmentation of particles have been developed separately in mainly two different disciplines: the continuous integro-differential equations of batch mineral grinding (Reid, 1965) and the fractal analysis of geophysics (Turcotte, 1986) based on a discrete model with a single probability of fracture. The first gives a time-dependent development of the particle-size distribution, but has resisted a closed-form solution, while the latter leads to the scale-invariant power laws, but with no time dependence. Bird (2009) recently introduced a bridge between these two approaches with a step-wise iterative calculation of the fragmentation products. The development of the particle-size distribution occurs with discrete steps: during each fragmentation event, the particles will repeatedly fracture probabilistically, cascading down the length scales to a final size distribution reached after all particles have failed to further fragment. We have identified this process as the equivalent to a sequence of trials for each particle with a fixed probability of fragmentation. Although the resulting distribution is discrete, it can be reformulated as a continuous distribution in maturity over time and particle size. In our model, Turcotte's power-law distribution emerges at a unique maturation index that defines a regime boundary. Up to this index, the fragmentation is in an erosional regime with the initial particle size setting the scaling. Fragmentation beyond this index is in a regime of comminution with rebreakage of the particles down to the size limit of fracture. The maturation index can increment continuously, for example under

  12. The southern hemisphere of 67P/Churyumov-Gerasimenko: Analysis of the preperihelion size-frequency distribution of boulders ≥7 m

    NASA Astrophysics Data System (ADS)

    Pajola, Maurizio; Lucchetti, Alice; Vincent, Jean-Baptiste; Oklay, Nilda; El-Maarry, Mohamed R.; Bertini, Ivano; Naletto, Giampiero; Lazzarin, Monica; Massironi, Matteo; Sierks, Holger; Barbieri, Cesare; Lamy, Philippe; Rodrigo, Rafael; Koschny, Detlef; Rickman, Hans; Keller, Horst U.; Agarwal, Jessica; A'Hearn, Michael F.; Barucci, Maria A.; Bertaux, Jean-Loup; Boudreault, Steve; Cremonese, Gabriele; Da Deppo, Vania; Davidsson, Björn; Debei, Stefano; De Cecco, Mariolino; Deller, Jakob; Fornasier, Sonia; Fulle, Marco; Gicquel, Adeline; Groussin, Olivier; Gutierrez, Pedro J.; Güttler, Carsten; Hofmann, Marc; Höfner, Sebastian; Hviid, Stubbe F.; Ip, Wing-Huen; Jorda, Laurent; Knollenberg, Jörg; Kramm, J.-Rainer; Kührt, Ekkehard; Küppers, Michael; La Forgia, Fiorangela; Lara, Luisa M.; Lee, Jui-Chi; Lin, Zhong-Yi; Lopez Moreno, Jose J.; Marzari, Francesco; Michalik, Harald; Mottola, Stefano; Preusker, Frank; Scholten, Frank; Thomas, Nicholas; Toth, Imre; Tubiana, Cecilia

    2016-07-01

    Aims: We calculate the size-frequency distribution of the boulders on the southern hemisphere of comet 67P Churyumov-Gerasimenko (67P), which was in shadow before the end of April 2015. We compare the new results with those derived from the northern hemisphere and equatorial regions of 67P, highlighting the possible physical processes that lead to these boulder size distributions. Methods: We used images acquired by the OSIRIS Narrow Angle Camera (NAC) on 2 May 2015 at a distance of 125 km from the nucleus. The scale of this dataset is 2.3 m/px; the high resolution of the images, coupled with the favorable observation phase angle of 62°, provided the possibility to unambiguously identify boulders ≥7 m on the surface of 67P and to manually extract them with the software ArcGIS. We derived the size-frequency distribution of the illuminated southern hemisphere. Results: We found a power-law index of -3.6 ± 0.2 for the boulders on the southern hemisphere with a diameter range of 7-35 m. The power-law index is equal to the one previously found on northern and equatorial regions of 67P, suggesting that similar boulder formation processes occur in both hemispheres. The power-law index is related to gravitational events triggered by sublimation and/or thermal fracturing causing regressive erosion. In addition, the presence of a larger number of boulders per km2 in the southern hemisphere, which is a factor of 3 higher with respect to the northern hemisphere, suggests that the southernmost terrains of 67P are affected by a stronger thermal fracturing and sublimating activity, hence possibly causing larger regressive erosion and gravitational events.

  13. The distribution of bubble sizes during reionization

    NASA Astrophysics Data System (ADS)

    Lin, Yin; Oh, S. Peng; Furlanetto, Steven R.; Sutter, P. M.

    2016-09-01

    A key physical quantity during reionization is the size of H II regions. Previous studies found a characteristic bubble size which increases rapidly during reionization, with apparent agreement between simulations and analytic excursion set theory. Using four different methods, we critically examine this claim. In particular, we introduce the use of the watershed algorithm - widely used for void finding in galaxy surveys - which we show to be an unbiased method with the lowest dispersion and best performance on Monte Carlo realizations of a known bubble size probability density function (PDF). We find that a friends-of-friends algorithm declares most of the ionized volume to be occupied by a network of volume-filling regions connected by narrow tunnels. For methods tuned to detect the volume-filling regions, previous apparent agreement between simulations and theory is spurious, and due to a failure to correctly account for the window function of measurement schemes. The discrepancy is already obvious from visual inspection. Instead, H II regions in simulations are significantly larger (by factors of 10-1000 in volume) than analytic predictions. The size PDF is narrower, and evolves more slowly with time, than predicted. It becomes more sharply peaked as reionization progresses. These effects are likely caused by bubble mergers, which are inadequately modelled by analytic theory. Our results have important consequences for high-redshift 21 cm observations, the mean free path of ionizing photons, and the visibility of Lyα emitters, and point to a fundamental failure in our understanding of the characteristic scales of the reionization process.

  14. Multimodal Dispersion of Nanoparticles: A Comprehensive Evaluation of Size Distribution with 9 Size Measurement Methods.

    PubMed

    Varenne, Fanny; Makky, Ali; Gaucher-Delmas, Mireille; Violleau, Frédéric; Vauthier, Christine

    2016-05-01

    Evaluation of particle size distribution (PSD) of multimodal dispersion of nanoparticles is a difficult task due to inherent limitations of size measurement methods. The present work reports the evaluation of PSD of a dispersion of poly(isobutylcyanoacrylate) nanoparticles decorated with dextran known as multimodal and developed as nanomedecine. The nine methods used were classified as batch particle i.e. Static Light Scattering (SLS) and Dynamic Light Scattering (DLS), single particle i.e. Electron Microscopy (EM), Atomic Force Microscopy (AFM), Tunable Resistive Pulse Sensing (TRPS) and Nanoparticle Tracking Analysis (NTA) and separative particle i.e. Asymmetrical Flow Field-Flow Fractionation coupled with DLS (AsFlFFF) size measurement methods. The multimodal dispersion was identified using AFM, TRPS and NTA and results were consistent with those provided with the method based on a separation step prior to on-line size measurements. None of the light scattering batch methods could reveal the complexity of the PSD of the dispersion. Difference between PSD obtained from all size measurement methods tested suggested that study of the PSD of multimodal dispersion required to analyze samples by at least one of the single size particle measurement method or a method that uses a separation step prior PSD measurement.

  15. Morphology, size distribution and elemental composition of several dental debris

    NASA Astrophysics Data System (ADS)

    Abe, Shigeaki; Iwadera, Nobuki; Esaki, Mitsue; Aoyama, Ken-Ichi; Akasaka, Tsukasa; Uo, Motohiro; Morita, Manabu; Yawaka, Yasutaka; Watari, Fumio

    2012-12-01

    We investigated morphologies, size distributions and elemental compositions of dental debris formed by cutting/grinding teeth or dental alloys. The average size of debris formed by cutting/grinding dental alloy was around 100 μm and that of teeth was 20 μm. The debris formed by grinding with diamond or carborundum point had isotropic irregular shape, while the debris formed by cutting with carbide bar had characteristic lathe-cut shape. The elemental analysis indicated that the debris formed by grinding dental alloy with carborundum point consisted of not only the particles of the alloy but also the particles of Si compounds with the size of around 10 μm. The particles of Si compounds would be formed by abrasion of the grinding instrument (carborundum, SiC). Similarly, the debris formed by grinding with diamond point also contained submicro-sized particles consisting of C compounds. The results indicate that the morphology and composition of dental debris are varied depending on the combination between the workpiece and the cutting/grinding materials and that the dental debris consist of both the workpiece and the cutting/grinding materials in some combination. In addition, some of the debris of tooth had the size less than 2 μm, which has a potential to induce inflammation. Though the inflammation can be expected at low level, it is required to investigate the details in future.

  16. Evaluation of and Suggested Improvements to the Morrison Microphysics in WRF Model. Part I: Analysis on Triple-moment Size Distribution Function and Sedimentation Section

    NASA Astrophysics Data System (ADS)

    Shan, Y.; Wilcox, E. M.; Zhao, T.; Yin, Y.; Gao, L.

    2016-12-01

    Observed rain droplet size distribution (DSD) could be employed to evaluate fitting ability of assumed size distribution functions (SDF) in bulk microphysics schemes, such as M-P Distribution and Gamma Distribution. Former observation studies used look-up table or fixed moment group methods to solve parameters in M-P SDF and Gamma SDF in order to fit observed DSDs. But these methods could hardly be applied into microphysics scheme directly, because only source/sink terms of zeroth and third order moments are possibly simulated in microphysics schemes. So, this study evaluated multiple parameter-solving methods available to microphysics schemes and quantified reliabilities of each ones. By comparison, more than 50% relative error for first to sixth order moments caused by M-P SDF could be modified, when it was replaced by a Gamma SDF with a diagnosed shape parameter. The improvement could be up to over 75% when solved shape parameter methods were used. These advantages of Gamma SDF showed requirement and possibility to add the third predicted parameter, namely the shape parameter, into SDF. Further, sedimentation section in Morrison Scheme was divided from its source code and converted into a triple-moment version. Then both original and converted versions were evaluated based on DSDs observed on three different heights. By analyzing source/sink terms and some modification, modeled number mixing ratio could be in same magnitude range with observed data. Summarized experiment results in this paper could serve as suggestions about how to develop and improve a triple-moment Morrison Microphysics Scheme.

  17. Determination of the mineral distribution in pulverized coal using densitometry and laser particle sizing

    SciTech Connect

    Hong Zhang; Yan-xue Mo; Ming Sun; Xian-yong Wei

    2005-12-01

    Coal particle size and mineral matter content have important effects on coal combustion. The mineral content of five Chinese coals was determined by a method combining densitometry and particle-size analysis. The finer particles of pulverized samples were found to contain more mineral content. Rank also had a significant influence on the particle-size ash-content distribution of pulverized coal particles. The sharpest size-ash distribution was found in pulverized anthracite samples; a broader distribution was found with bituminous coal samples, while a uniform distribution was observed in pulverized lignite samples. Ash in higher ash anthracite or lower ash bituminous coal is more evenly distributed. It is a combined effect of size distribution, yield, and proximate analysis of their density separation fractions. Mineral matter tends to distribute more evenly in finer pulverized coals. This results from a relative increase of the low-density fraction in the finer particles. 13 refs., 10 figs., 10 tabs.

  18. Lunar soil: Size distribution and mineralogical constituents

    USGS Publications Warehouse

    Duke, M.B.; Woo, C.C.; Bird, M.L.; Sellers, G.A.; Finkelman, R.B.

    1970-01-01

    The lunar soil collected by Apollo 11 consists primarily of submillimeter material and is finer in grain size than soil previously recorded photographically by Surveyor experiments. The main constituents are fine-grained to glassy rocks of basaltic affinity and coherent breccia of undetermined origin. Dark glass, containing abundant nickel-iron spheres, coats many rocks, mineral, and breccia fragments. Several types of homogeneous glass occur as fragments and spheres. Colorless spheres, probably an exotic component, are abundant in the fraction finer than 20 microns.

  19. Universal functional form of 1-minute raindrop size distribution?

    NASA Astrophysics Data System (ADS)

    Cugerone, Katia; De Michele, Carlo

    2015-04-01

    Rainfall remains one of the poorly quantified phenomena of the hydrological cycle, despite its fundamental role. No universal laws describing the rainfall behavior are available in literature. This is probably due to the continuous description of rainfall, which is a discrete phenomenon, made by drops. From the statistical point of view, the rainfall variability at particle size scale, is described by the drop size distribution (DSD). With this term, it is generally indicated as the concentration of raindrops per unit volume and diameter, as the probability density function of drop diameter at the ground, according to the specific problem of interest. Raindrops represent the water exchange, under liquid form, between atmosphere and earth surface, and the number of drops and their size have impacts in a wide range of hydrologic, meteorologic, and ecologic phenomena. DSD is used, for example, to measure the multiwavelength rain attenuation for terrestrial and satellite systems, it is an important input for the evaluation of the below cloud scavenging coefficient of the aerosol by precipitation, and is of primary importance to make estimates of rainfall rate through radars. In literature, many distributions have been used to this aim (Gamma and Lognormal above all), without statistical supports and with site-specific studies. Here, we present an extensive investigation of raindrop size distribution based on 18 datasets, consisting in 1-minute disdrometer data, sampled using Joss-Waldvogel or Thies instrument in different locations on Earth's surface. The aim is to understand if an universal functional form of 1-minute drop diameter variability exists. The study consists of three main steps: analysis of the high order moments, selection of the model through the AIC index and test of the model with the use of goodness-of-fit tests.

  20. The size distribution of inhabited planets

    NASA Astrophysics Data System (ADS)

    Simpson, Fergus

    2016-02-01

    Earth-like planets are expected to provide the greatest opportunity for the detection of life beyond the Solar system. However, our planet cannot be considered a fair sample, especially if intelligent life exists elsewhere. Just as a person's country of origin is a biased sample among countries, so too their planet of origin may be a biased sample among planets. The magnitude of this effect can be substantial: over 98 per cent of the world's population live in a country larger than the median. In the context of a simple model where the mean population density is invariant to planet size, we infer that a given inhabited planet (such as our nearest neighbour) has a radius r < 1.2r⊕ (95 per cent confidence bound). We show that this result is likely to hold not only for planets hosting advanced life, but also for those which harbour primitive life forms. Further, inferences may be drawn for any variable which influences population size. For example, since population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300 kg.

  1. Shape, size, and distribution of magnetic particles in Bjurbole chondrules

    NASA Technical Reports Server (NTRS)

    Nava, David F.

    1994-01-01

    Chondrules from the Bjurbole chondritic meteorite (L4) exhibit saturation remanence magnetization (SIRM) values which vary over three orders of magnitude. REM values (Natural Remanence Magnetization/SIRM) for Allende (C3V) and Chainpur (LL3) are less than 0.01 but in Bjurbole some chondrules were found to have REM values greater than 0.1 with several greater than 0.2. REM values greater than 0.1 are abnormal and cannot be acquired during weak field cooling. If exposure to a strong field (whatever the source) during the chondrules' history is responsible for the high REM values, was such history associated with a different processing which might have resulted in different shape, size, and distribution of metal particles compared to chondrules having REM values of less than 0.01? Furthermore, magnetic hysteresis results show a broad range of magnetic hardness and other intrinsic magnetic properties. These features must be related to (1) size and amount of metal; and (2) properties of, and amount of, tetrataenite in the chondrules (all chondrules thus far subjected to thermomagnetic analysis show the presence of tetrataenite). A scanning electron microscopy (SEM) study is underway to determine the relationship between the shape, size, and distribution of metal particles within individual chondrules and the magnetic properties of these chondrules. Results from the SEM study in conjunction with magnetic property data may also help to discern effects from possible lightning strikes in the nebula prior to incorporation of the chondrules into the parent body.

  2. Optical heterodyne measurement of cloud droplet size distributions.

    PubMed

    Gollub, J P; Chabay, L; Flygare, W H

    1973-12-01

    Optical heterodyne spectra of laser light quasi-elastically scattered by falling water droplets (1-10-micro radius) in a diffusion cloud chamber were used to determine the droplet size distribution. The rate of fall depends on radius in a known way, thus yielding a heterodyne spectrum manifesting a distribution of Doppler shifts. This spectrum, in conjunction with the calculated Mie scattering intensity as a function of droplet radius, provides a direct measure of the droplet size distribution for droplets large enough that Brownian motion is negligible. The experiments described in this paper demonstrate the technique and establish the potential for further more quantitative studies of size distributions.

  3. The equilibrium size distribution of rouleaux.

    PubMed Central

    Perelson, A S; Wiegel, F W

    1982-01-01

    Rouleaux are formed by the aggregation of red blood cells in the presence of macromolecules that bridge the membranes of adherent erythrocytes. We compute the size and degree of branching of rouleaux for macroscopic systems in thermal equilibrium in the absence of fluid flow. Using techniques from statistical mechanics, analytical expressions are derived for (a) the average number of rouleaux consisting of n cells and having m branch points; (b) the average number of cells per rouleau; (c) the average number of branch points per rouleau; and (d) the number of rouleaux with n cells, n = 1, 2, ..., in a system containing a total of N cells. We also present the results of numerical evaluations to establish the validity of asymptotic expressions that simplify our formal analytic results. Images FIGURE 1 PMID:7059653

  4. Empirical Reference Distributions for Networks of Different Size

    PubMed Central

    Smith, Anna; Calder, Catherine A.; Browning, Christopher R.

    2016-01-01

    Network analysis has become an increasingly prevalent research tool across a vast range of scientific fields. Here, we focus on the particular issue of comparing network statistics, i.e. graph-level measures of network structural features, across multiple networks that differ in size. Although “normalized” versions of some network statistics exist, we demonstrate via simulation why direct comparison is often inappropriate. We consider normalizing network statistics relative to a simple fully parameterized reference distribution and demonstrate via simulation how this is an improvement over direct comparison, but still sometimes problematic. We propose a new adjustment method based on a reference distribution constructed as a mixture model of random graphs which reflect the dependence structure exhibited in the observed networks. We show that using simple Bernoulli models as mixture components in this reference distribution can provide adjusted network statistics that are relatively comparable across different network sizes but still describe interesting features of networks, and that this can be accomplished at relatively low computational expense. Finally, we apply this methodology to a collection of ecological networks derived from the Los Angeles Family and Neighborhood Survey activity location data. PMID:27721556

  5. Estimating Flaw Size Distributions From Service Inspection Results (Preprint)

    DTIC Science & Technology

    2006-12-01

    equivalent initial flaw size model...the adequacy of the model, only whether or not the parameters are equal to 0. One reason the model did not fit well is that the equivalent initial flaw size (EIFS...curve model was used along with a lognormal equivalent initial flaw size distribution. The parameter values were chosen to approximate the real

  6. Powder Size and Distribution in Ultrasonic Gas Atomization

    NASA Astrophysics Data System (ADS)

    Rai, G.; Lavernia, E.; Grant, N. J.

    1985-08-01

    Ultrasonic gas atomization (USGA) produces powder sizes dependent on the ratio of the nozzle jet diameter to the distance of spread dt/R, Powder size distribution is attributed to the spread of atomizing gas jets during travel from the nozzle exit to the metal stream. The spread diminishes at higher gas atomization pressures. In this paper, calculated powder sizes and distribution are compared with experimentally determined values.

  7. Size distribution of Amazon River bed sediment

    USGS Publications Warehouse

    Nordin, C.F.; Meade, R.H.; Curtis, W.F.; Bosio, N.J.; Landim, P.M.B.

    1980-01-01

    The first recorded observations of bed material of the Amazon River were made in 1843 by Lt William Lewis Herndon of the US Navy, when he travelled the river from its headwaters to its mouth, sounding its depths, and noting the nature of particles caught in a heavy grease smeared to the bottom of his sounding weight1. He reported the bed material of the river to be mostly sand and fine gravel. Oltman and Ames took samples at a few locations in 1963 and 1964, and reported the bed material at O??bidos, Brazil, to be fine sands, with median diameters ranging from 0.15 to 0.25 mm (ref. 2). We present here a summary of particle-size analyses of samples of streambed material collected from the Amazon River and its major tributaries along a reach of the river from Iquitos in Peru, ???3,500 km above Macapa?? Brazil, to a point 220 km above Macapa??3. ?? 1980 Nature Publishing Group.

  8. Initial size distributions and hygroscopicity of indoor combustion aerosol particles

    SciTech Connect

    Li, W.; Hopke, P.K.

    1993-10-01

    Cigarette smoke, incense smoke, natural gas flames, propane fuel flames, and candle flames are contributors of indoor aerosol particles. To provide a quantitative basis for the modeling of inhaled aerosol deposition pattern, the hygroscopic growth of particles from these five sources as well as the source size distributions were measured. Because the experiments were performed on the bases of particles of single size, it provided not only the averaged particle`s hygroscopic growth of each source, but also the detailed size change for particles of different sizes within the whole size spectrum. The source particle size distribution measurements found that cigarette smoke and incense smoke contained particles in the size range of 100-700 nm, while the natural gas, propane, and candle flames generated particles between 10 and 100 nm. The hygroscopic growth experiments showed that these combustion aerosol particles could grow 10% to 120%, depending on the particle sizes and origins. 18 refs., 15 figs., 3 tabs.

  9. AnalySize: New software for analyzing and unmixing sediment grain size distribution spectra

    NASA Astrophysics Data System (ADS)

    Paterson, G. A.; Heslop, D.

    2015-12-01

    Grain size distribution (GSD) data are a widely used tool in Earth sciences, particularly in understanding sediment transportation and sourcing. Although large data sets are regularly generated, detailed numerical analyses, such as grain size unmixing, are not routinely performed. Unmixing of GSD data involves approximating a given data set by a small number of GSDs, known as end members. These end members, along with their relative abundances, can be used to fully characterize the variability of the data. End member analysis (EMA), which fits one set of end members to a single data set, is one the most robust ways to do this. This approach estimates the form of the end members from the data set itself; hence it is a non-parametric approach. Available algorithms, however, either produce sub-optimal solutions, or are time consuming. To aid investigators in exploring the full potential of their data, we introduce AnalySize, which is a GUI based tool that allows for comprehensive processing and unmixing of grain size data obtained from laser diffraction particle grain size analyzers. AnalySize brings together methods from other disciplines in Earth sciences as well as introducing new techniques and improvements to provide a complete software package for unmixing GSD data. The software utilizes the rapid HALS-NMF algorithm from hyperspectral image analysis to perform non-parametric EMA, which is demonstrated to yield results that are an improvement over algorithms currently used in GSD analysis. Non-parametric EMA, however, is often unable to clearly identify discrete unimodal grain size sub-populations, which can more detailed information about sediment sources. To alleviate this, we introduce a new algorithm to perform parametric EMA, whereby an entire GSD data set can be unmixed into unimodal parametric end members (e.g., lognormal or Weibull end members). This allows individual grain size sub-populations to be more readily identifiable in highly mixed data set

  10. Size distribution of folded chain crystal nuclei of polyethylene on active centers.

    PubMed

    Kožíšek, Zdeněk; Hikosaka, Masamichi; Okada, Kiyoka; Demo, Pavel

    2011-03-21

    Kinetic equations describing temporal evolution of the size distribution of crystalline nuclei of folded chain polyethylene on active centers are solved numerically. Basic characteristics of nucleation processes (the total number of supercritical nuclei and the size distribution of nuclei) are determined and compared with the experimental data. It is shown that even though the total number of supercritical nuclei coincides with the experimental data, the size distribution prediction fails. This is caused by the fact that the total number of nuclei (usually used in analysis of the experimental data), in contrast to the size distribution of nuclei, represents an integral quantity. Using the experimental data of the steady state size distribution of nuclei enables us to determine thermodynamic parameters (especially interfacial energies) of the studied system more precisely and consequently to correct kinetic parameters to get coincidence of kinetic model with the experimental data in both, the total number of supercritical nuclei and also the size distribution of nuclei.

  11. Measurement of non-volatile particle number size distribution

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G. I.; Papanastasiou, D. K.; Florou, K.; Kaltsonoudis, C.; Louvaris, E.; Pandis, S. N.

    2015-06-01

    An experimental methodology was developed to measure the non-volatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a non-volatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol, OA (40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50-60 % of the particles had a non-volatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon (BC) with an 80 % contribution, while OA was responsible for another 15-20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type

  12. Size distributions of quantum islands on stepped substrates.

    PubMed

    Liang, S; Zhu, H L; Wang, W

    2009-10-21

    The size distributions of self-assembled quantum islands on stepped substrates are studied using kinetic Monte Carlo simulations. It is found that the energy barrier E(SW) between the step and the terrace region is the key factor in affecting the size distribution of islands. With small E(SW) (< or = 0.1 eV), lines of uniform islands can be obtained at relative low surface coverage. As the surface coverage is increased, wirelike islands can be obtained. Scaling behavior is obeyed for the size distributions of the wirelike islands. When the size distributions are separated into their width and length components, however, scaling is only observed in the length distribution of the wirelike islands. With larger E(SW), the size distribution of islands shows a clear bimodal size distribution and anomalous growth temperature dependent island size evolutions are observed. The simulation results reproduce qualitatively the phenomena observed in the cases of InAs islands grown on stepped GaAs substrates.

  13. Distributed analysis in ATLAS

    NASA Astrophysics Data System (ADS)

    Dewhurst, A.; Legger, F.

    2015-12-01

    The ATLAS experiment accumulated more than 140 PB of data during the first run of the Large Hadron Collider (LHC) at CERN. The analysis of such an amount of data is a challenging task for the distributed physics community. The Distributed Analysis (DA) system of the ATLAS experiment is an established and stable component of the ATLAS distributed computing operations. About half a million user jobs are running daily on DA resources, submitted by more than 1500 ATLAS physicists. The reliability of the DA system during the first run of the LHC and the following shutdown period has been high thanks to the continuous automatic validation of the distributed analysis sites and the user support provided by a dedicated team of expert shifters. During the LHC shutdown, the ATLAS computing model has undergone several changes to improve the analysis workflows, including the re-design of the production system, a new analysis data format and event model, and the development of common reduction and analysis frameworks. We report on the impact such changes have on the DA infrastructure, describe the new DA components, and include recent performance measurements.

  14. THE COLLISIONAL DIVOT IN THE KUIPER BELT SIZE DISTRIBUTION

    SciTech Connect

    Fraser, Wesley C.

    2009-11-20

    This paper presents the results of collisional evolution calculations for the Kuiper Belt starting from an initial size distribution similar to that produced by accretion simulations of that region-a steep power-law large object size distribution that breaks to a shallower slope at r approx 1-2 km, with collisional equilibrium achieved for objects r approx< 0.5 km. We find that the break from the steep large object power law causes a divot, or depletion of objects at r approx 10-20 km, which, in turn, greatly reduces the disruption rate of objects with r approx> 25-50 km, preserving the steep power-law behavior for objects at this size. Our calculations demonstrate that the roll-over observed in the Kuiper Belt size distribution is naturally explained as an edge of a divot in the size distribution; the radius at which the size distribution transitions away from the power law, and the shape of the divot from our simulations are consistent with the size of the observed roll-over, and size distribution for smaller bodies. Both the kink radius and the radius of the divot center depend on the strength scaling law in the gravity regime for Kuiper Belt objects. These simulations suggest that the sky density of r approx 1 km objects is approx10{sup 6}-10{sup 7} objects per square degree. A detection of the divot in the size distribution would provide a measure of the strength of large Kuiper Belt objects, and constrain the shape of the size distribution at the end of accretion in the Kuiper Belt.

  15. Development of equilibrium raindrop size distribution in natural rain.

    NASA Astrophysics Data System (ADS)

    Pio D'Adderio, Leo; Porcu, Federico; Tokay, Ali

    2015-04-01

    The NASA's Global Precipitation Measurement (GPM) mission dual-frequency precipitation radar retrieval has adopted a three-parameter gamma distribution to retrieve the raindrop size distribution (DSD) from dual-frequency precipitation radar (DPR) measurements. Recent analysis from disdrometric measurements collected during GPM ground validation (GV) field experiments shows that the three-parameter gamma distribution does not well fit the observed spectra in the presence of collisional break-up, i.e. when the DSD reaches the equilibrium stage. An automatic algorithm is used to select equilibrium DSD in six datasets for a total number of more than 12,000 minutes with rain rate higher than 5 mmh-1 collected from 2-DVD disdrometers. The algorithm is based on the analysis of the DSD slope in the interval 1.0-2.5 mm diameter. The 1-minute time series are studied in order to assess the conditions more favorable for equilibrium DSD to take place, showing the transition between the one-peak DSD to the 2-peak DSD, for selected case studies, over a wide range of rainrate values. The results are discussed in terms of precipitation type and intensity, showing a very rapid onset and dissipation of equilibrium DSD conditions. The temporal evolution of some DSD parameters is also analyzed, and, for two of the six datasets (MC3E and Wallops), was also possible to evaluate the small-scale spatial structure of equilibrium DSD.

  16. Analysis of the atmospheric aerosol size distribution information retrievable from near-limb angular radiance measurements taken on Mauna Loa, Hawaii

    SciTech Connect

    Grant, K.E.

    1981-12-01

    Angular radiance measurements of the near-limb solar aureole were analyzed for information regarding the light-scattering aerosol particles in the atmospheric column above Mauna Loa, Hawaii. The Mauna Loa Observatory, located at 19/sup 0/ 33' N latitude, 155/sup 0/ 35' W longitude, and 3460 metres elevation, is in unpolluted air above the easterly trade wind inversion and has been designated as a site for the Geophysical Monitoring for Climatic Change (GMCC) program. Circumsolar radiance and polarization measurements have been collected on Mauna Loa since 1963 by the High Altitude Observatory (HAO), National Center for Atmospheric Research (NCAR) as part of a program for the daily observation of the solar corona. Strip charts containing radiance measurements made from January 1976 through June 1978 were made available for this study. By the use of Mie scattering theory, generalized to treat the sun as a finite diameter light source with limb-darkening, a theoretical scattering matrix was calculated for observation angles between 17' and 300' measured from the center of the solar disk, and aerosol size parameters (2..pi..r/lambda) between 10 and 300. An information content criterion is presented, based on the expected relative norm of the measurement errors and on the eigenvalues of the radiance covariance matrix of the scattering matrix. The observed aureole radiance gradients and two test gradients were inverted to obtain aerosol size distributions using a constrained linear inversion algorithm.

  17. Intercomparison of 15 aerodynamic particle size spectrometers (APS 3321): uncertainties in particle sizing and number size distribution

    NASA Astrophysics Data System (ADS)

    Pfeifer, S.; Müller, T.; Weinhold, K.; Zikova, N.; Santos, S.; Marinoni, A.; Bischof, O. F.; Kykal, C.; Ries, L.; Meinhardt, F.; Aalto, P.; Mihalopoulos, N.; Wiedensohler, A.

    2015-11-01

    Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network), 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA) were compared with a focus on flow rates accuracy, particle sizing, and unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent), while the sizing accuracy was found to be within 10 % compared to polystyrene latex (PSL) reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10-20 % for particles in the range of 0.9 up to 3 μm, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60 %, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9 μm in aerodynamic diameter should be only used with caution. For particles larger than 3 μm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. This uncertainty of the particle number size distribution has especially to be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size range 0.5-3

  18. Intercomparison of 15 aerodynamic particle size spectrometers (APS 3321): uncertainties in particle sizing and number size distribution

    NASA Astrophysics Data System (ADS)

    Pfeifer, Sascha; Müller, Thomas; Weinhold, Kay; Zikova, Nadezda; Martins dos Santos, Sebastiao; Marinoni, Angela; Bischof, Oliver F.; Kykal, Carsten; Ries, Ludwig; Meinhardt, Frank; Aalto, Pasi; Mihalopoulos, Nikolaos; Wiedensohler, Alfred

    2016-04-01

    Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network), 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA) were compared with a focus on flow rates, particle sizing, and the unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent), while the sizing accuracy was found to be within 10 % compared to polystyrene latex (PSL) reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10 % to 20 % for particles in the range of 0.9 up to 3 µm, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60 %, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9 µm in aerodynamic diameter should only be used with caution. For particles larger than 3 µm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. Particularly this uncertainty of the particle number size distribution must be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size range 0.5-3 µm

  19. The Size Distribution of Jupiter-Family Cometary Nuclei

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.; Lowry, Stephen C.

    2003-01-01

    Introduction: We are continuing our program to determine the size distribution of cometary nuclei. We have compiled a catalog of 105 measurements of 57 cometary nuclei, drawn from the general literature, from our own program of CCD photometry of distant cometary nuclei (Lowry and Weissman), and from unpublished observations by colleagues. We model the cumulative size distribution of the nuclei as a power law. Previous determinations of the size distribution slope do not agree. Fernandez et al. found a slope of alpha = 2.65+/-0.25 whereas Lowry et al. and Weissman and Lowry each found a slope of alpha = 1.60+/-0.10.

  20. Free Volume Size Distribution in Some Natural Polymers

    NASA Astrophysics Data System (ADS)

    Chandrashekara, M. N.; Ranganathaiah, C.

    2011-07-01

    Positron lifetime technique was used to determine the size distribution of free volume holes in some natural polymers-animal hair, feather, cotton and silk. The effect of fiber swelling on the nature of size distribution was also monitored. The obtained positron lifetime spectra were analyzed by using the computer program CONTIN (PALS-2). Significant differences in the size distribution were observed for these biological polymers (and even among the different animal hair types), possibly due to the structural differences, which have not been investigated hitherto.

  1. Pore-size-distribution of cationic polyacrylamide hydrogels. Progress report

    SciTech Connect

    Kremer, M.; Prausnitz, J.M.

    1992-06-01

    The pore size distribution of a AAm/MAPTAC (acrylamide copolymerized with (3-methacrylamidopropyl)trimethylammonium chloride) hydrogel was investigated using Kuga`s mixed-solute-exclusion method, taking into account the wall effect. A Brownian-motion model is also used. Results show the feasibility of determining pore-size distribution of porous materials using the mixed-solute-exclusion method in conjunction with solution of the Fredholm equation; good agreement was obtained with experiment, even for bimodal pore structures. However, different pore size distributions were calculated for the two different probe-solutes (Dextran and poly(ethylene glycol/oxide)). Future work is outlined. 32 figs, 25 refs.

  2. Pore-size-distribution of cationic polyacrylamide hydrogels

    SciTech Connect

    Kremer, M.; Prausnitz, J.M.

    1992-06-01

    The pore size distribution of a AAm/MAPTAC (acrylamide copolymerized with (3-methacrylamidopropyl)trimethylammonium chloride) hydrogel was investigated using Kuga's mixed-solute-exclusion method, taking into account the wall effect. A Brownian-motion model is also used. Results show the feasibility of determining pore-size distribution of porous materials using the mixed-solute-exclusion method in conjunction with solution of the Fredholm equation; good agreement was obtained with experiment, even for bimodal pore structures. However, different pore size distributions were calculated for the two different probe-solutes (Dextran and poly(ethylene glycol/oxide)). Future work is outlined. 32 figs, 25 refs.

  3. The Size Distribution of Jupiter-Family Cometary Nuclei

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.; Lowry, Stephen C.

    2003-01-01

    Introduction: We are continuing our program to determine the size distribution of cometary nuclei. We have compiled a catalog of 105 measurements of 57 cometary nuclei, drawn from the general literature, from our own program of CCD photometry of distant cometary nuclei (Lowry and Weissman), and from unpublished observations by colleagues. We model the cumulative size distribution of the nuclei as a power law. Previous determinations of the size distribution slope do not agree. Fernandez et al. found a slope of alpha = 2.65+/-0.25 whereas Lowry et al. and Weissman and Lowry each found a slope of alpha = 1.60+/-0.10.

  4. Impact of microphysical processes on ice crystal size distributions

    NASA Astrophysics Data System (ADS)

    Lüttmer, Tim; Spichtinger, Peter

    2017-04-01

    Cirrus clouds affect the Earth's radiation budget significantly. Their radiative properties depend on the microphysical properties and ice crystal size distribution. Microphysical processes affect the type and structure of ice crystal distributions strongly. However, bulk microphysics schemes are not able to represent changes in distribution type; thus, effects concerning changes in the distribution cannot be investigated using such simplified parameterizations. A size-resolved bin model was developed to study the influence of microphysical processes on ice crystal size distributions of cirrus clouds. The model is based on a consistent treatment of the relevant processes and ice crystal properties. Results of 1-D simulations investigating the temporal and spatial evolution of cirrus ice distributions under various idealized environmental conditions are presented. Emphasis is placed on the effects of sedimentation and depositional growth, but other processes such as ice nucleation are also considered in the simulations.

  5. A stability analysis of a modified version of the chi-square ratio statistic: implications for equivalence testing of aerodynamic particle size distribution.

    PubMed

    Weber, Benjamin; Hochhaus, Guenther; Adams, Wallace; Lionberger, Robert; Li, Bing; Tsong, Yi; Lee, Sau L

    2013-01-01

    Demonstration of equivalence in aerodynamic particle size distribution (APSD; e.g., by comparing cascade impactor (CI) profiles) constitutes one of key in vitro tests for supporting bioequivalence between test (T) and reference (R) orally inhaled drug products (OIDPs). A chi-square ratio statistic (CSRS) was previously proposed for equivalence testing of CI profiles. However, it was reported that the CSRS could not consistently discriminate between equivalent and inequivalent CI profiles. The objective of the overall project was to develop a robust and sensitive methodology for assessing equivalence of APSD profiles of T and R OIDPs. We propose here a modified version of the CSRS (mCSRS) and evaluated systematically its behavior when T and R CI profiles were identical. Different scenarios comprising CI profiles with different number of deposition sites and shapes were generated by Monte-Carlo simulation. For each scenario, the mCSRS was applied to 20,000 independent sets of 30 T and 30 R CI profiles that were identical. Different metrics (including mean and median) of the distribution of 900 mCSRSs (30 T × 30 R) were then evaluated for their suitability as a test statistic (i.e., independent of the number of sites and shape of the CI profile) for APSD equivalence testing. The median of the distribution of 900 mCSRSs (MmCSRS) was one regardless of the number of sites and shape of the CI profile. Hence, the MmCSRS is a robust metric for CI profile equivalence testing when T and R CI profiles are identical and potentially useful for APSD equivalence testing.

  6. Environmental control of natural gap size distribution in tropical forests

    NASA Astrophysics Data System (ADS)

    Goulamoussène, Youven; Bedeau, Caroline; Descroix, Laurent; Linguet, Laurent; Hérault, Bruno

    2017-01-01

    Natural disturbances are the dominant form of forest regeneration and dynamics in unmanaged tropical forests. Monitoring the size distribution of treefall gaps is important to better understand and predict the carbon budget in response to land use and other global changes. In this study, we model the size frequency distribution of natural canopy gaps with a discrete power law distribution. We use a Bayesian framework to introduce and test, using Monte Carlo Markov chain and Kuo-Mallick algorithms, the effect of local physical environment on gap size distribution. We apply our methodological framework to an original light detecting and ranging dataset in which natural forest gaps were delineated over 30 000 ha of unmanaged forest. We highlight strong links between gap size distribution and environment, primarily hydrological conditions and topography, with large gaps being more frequent on floodplains and in wind-exposed areas. In the future, we plan to apply our methodological framework on a larger scale using satellite data. Additionally, although gap size distribution variation is clearly under environmental control, variation in gap size distribution in time should be tested against climate variability.

  7. What We Can Learn From Supernova Remnant Size Distributions

    NASA Astrophysics Data System (ADS)

    Elwood, Benjamin; Murphy, Jeremiah; Diaz, Mariangelly

    2016-01-01

    Previous literature regarding size distributions of supernova remnants generally discuss a uniform distribution for the radius, occasionally considering a Gaussian alternative. We indeed show that these distributions are consistent with log-normal, which can be considered a natural consequence of the Central Limit Theorem and Sedov expansion. Modeling explosion energy, remnant age, and ambient density as independent, random distributions, we show, using simple Monte Carlo simulations, that the size distribution is indistinguishable from log-normal when the SNR sample size is of order three hundred. This implies that these SNR distributions provide only information on the mean and variance, yielding additional information only when the sample size grows large. We then proceed to Bayesian statistical inference to characterize the information provided by the size distributions. In particular, we use the mean and variance of sizes and explosion energies to subsequently estimate the mean and variance of the ambient medium surrounding SNR progenitors. This in turn allows us to characterize potential bias in studies involving samples of supernova remnants.

  8. Effects of Mixtures on Liquid and Solid Fragment Size Distributions

    DTIC Science & Technology

    2016-05-01

    treated steel ; 67.0/ mn Table 11 gives examples of size distributions taken from the research literature on atomization and sprays where mn...impact (0.5–2.0 km/s) on thin steel plates.” More specifically, he studied “spherical porous aluminum projectiles 2.51 cm in diameter … cut from a...Effects of Mixtures on Liquid and Solid Fragment Size Distributions Distribution Statement A. Approved for public release; distribution is unlimited

  9. Self-consistent Size and Velocity Distributions of Collisional Cascades

    NASA Astrophysics Data System (ADS)

    Pan, Margaret; Schlichting, Hilke E.

    2012-03-01

    The standard theoretical treatment of collisional cascades derives a steady-state size distribution assuming a single constant velocity dispersion for all bodies regardless of size. Here we relax this assumption and solve self-consistently for the bodies' steady-state size and size-dependent velocity distributions. Specifically, we account for viscous stirring, dynamical friction, and collisional damping of the bodies' random velocities in addition to the mass conservation requirement typically applied to find the size distribution in a steady-state cascade. The resulting size distributions are significantly steeper than those derived without velocity evolution. For example, accounting self-consistently for the velocities can change the standard q = 3.5 power-law index of the Dohnanyi differential size spectrum to an index as large as q = 4. Similarly, for bodies held together by their own gravity, the corresponding power-law index range 2.88 < q < 3.14 of Pan & Sari can steepen to values as large as q = 3.26. Our velocity results allow quantitative predictions of the bodies' scale heights as a function of size. Together with our predictions, observations of the scale heights for different-sized bodies for the Kuiper belt, the asteroid belt, and extrasolar debris disks may constrain the mass and number of large bodies stirring the cascade as well as the colliding bodies' internal strengths.

  10. SELF-CONSISTENT SIZE AND VELOCITY DISTRIBUTIONS OF COLLISIONAL CASCADES

    SciTech Connect

    Pan, Margaret; Schlichting, Hilke E. E-mail: hilke@ucla.edu

    2012-03-10

    The standard theoretical treatment of collisional cascades derives a steady-state size distribution assuming a single constant velocity dispersion for all bodies regardless of size. Here we relax this assumption and solve self-consistently for the bodies' steady-state size and size-dependent velocity distributions. Specifically, we account for viscous stirring, dynamical friction, and collisional damping of the bodies' random velocities in addition to the mass conservation requirement typically applied to find the size distribution in a steady-state cascade. The resulting size distributions are significantly steeper than those derived without velocity evolution. For example, accounting self-consistently for the velocities can change the standard q = 3.5 power-law index of the Dohnanyi differential size spectrum to an index as large as q = 4. Similarly, for bodies held together by their own gravity, the corresponding power-law index range 2.88 < q < 3.14 of Pan and Sari can steepen to values as large as q = 3.26. Our velocity results allow quantitative predictions of the bodies' scale heights as a function of size. Together with our predictions, observations of the scale heights for different-sized bodies for the Kuiper belt, the asteroid belt, and extrasolar debris disks may constrain the mass and number of large bodies stirring the cascade as well as the colliding bodies' internal strengths.

  11. Appendix B: Summary of TEM Particle Size Distribution Datasets

    EPA Pesticide Factsheets

    As discussed in the main text (see Section 5.3.2), calculation of the concentration of asbestos fibers in each of the bins of potential interest requires particle size distribution data derived using transmission electron microscopy (TEM).

  12. Grain Size Distribution in the Matrix of Primitive Meteorites

    NASA Astrophysics Data System (ADS)

    Vaccaro, E.; Wozniakiewicz, P. J.; Starkey, N. A.; Franchi, I. A.; Russell, S. S.

    2015-07-01

    We describe the abundances and size distribution of discrete grains of different phases observed within the matrix of: Acfer 094, ALHA77307, MIL 07687 and QUE 99177 and discuss how the observed differences may be evidence of parent body processes.

  13. A model for predicting fog aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Rudiger, Joshua J.; Book, Kevin; Baker, Brooke; deGrassie, John Stephen; Hammel, Stephen

    2016-09-01

    An accurate model and parameterization of fog is needed to increase the reliability and usefulness of electro-optical systems in all relevant environments. Current models vary widely in their ability to accurately predict the size distribution and subsequent optical properties of fog. The Advanced Navy Aerosol Model (ANAM), developed to model the distribution of aerosols in the maritime environment, does not currently include a model for fog. One of the more prevalent methods for modeling particle size spectra consists of fitting a modified gamma function to fog measurement data. This limits the fog distribution to a single mode. Here we establish an empirical model for predicting complicated multimodal fog droplet size spectra using machine learning techniques. This is accomplished through careful measurements of fog in a controlled laboratory environment and measuring fog particle size distributions during outdoor fog events.

  14. The best nanoparticle size distribution for minimum thermal conductivity.

    PubMed

    Zhang, Hang; Minnich, Austin J

    2015-03-11

    Which sizes of nanoparticles embedded in a crystalline solid yield the lowest thermal conductivity? Nanoparticles have long been demonstrated to reduce the thermal conductivity of crystals by scattering phonons, but most previous works assumed the nanoparticles to have a single size. Here, we use optimization methods to show that the best nanoparticle size distribution to scatter the broad thermal phonon spectrum is not a similarly broad distribution but rather several discrete peaks at well-chosen nanoparticle radii. For SiGe, the best size distribution yields a thermal conductivity below that of amorphous silicon. Further, we demonstrate that a simplified distribution yields nearly the same low thermal conductivity and can be readily fabricated. Our work provides important insights into how to manipulate the full spectrum of phonons and will guide the design of more efficient thermoelectric materials.

  15. The best nanoparticle size distribution for minimum thermal conductivity

    PubMed Central

    Zhang, Hang; Minnich, Austin J.

    2015-01-01

    Which sizes of nanoparticles embedded in a crystalline solid yield the lowest thermal conductivity? Nanoparticles have long been demonstrated to reduce the thermal conductivity of crystals by scattering phonons, but most previous works assumed the nanoparticles to have a single size. Here, we use optimization methods to show that the best nanoparticle size distribution to scatter the broad thermal phonon spectrum is not a similarly broad distribution but rather several discrete peaks at well-chosen nanoparticle radii. For SiGe, the best size distribution yields a thermal conductivity below that of amorphous silicon. Further, we demonstrate that a simplified distribution yields nearly the same low thermal conductivity and can be readily fabricated. Our work provides important insights into how to manipulate the full spectrum of phonons and will guide the design of more efficient thermoelectric materials. PMID:25757414

  16. INITIAL PLANETESIMAL SIZES AND THE SIZE DISTRIBUTION OF SMALL KUIPER BELT OBJECTS

    SciTech Connect

    Schlichting, Hilke E.; Fuentes, Cesar I.; Trilling, David E.

    2013-08-01

    The Kuiper Belt is a remnant from the early solar system and its size distribution contains many important constraints that can be used to test models of planet formation and collisional evolution. We show, by comparing observations with theoretical models, that the observed Kuiper Belt size distribution is well matched by coagulation models, which start with an initial planetesimal population with radii of about 1 km, and subsequent collisional evolution. We find that the observed size distribution above R {approx} 30 km is primordial, i.e., it has not been modified by collisional evolution over the age of the solar system, and that the size distribution below R {approx} 30 km has been modified by collisions and that its slope is well matched by collisional evolution models that use published strength laws. We investigate in detail the resulting size distribution of bodies ranging from 0.01 km to 30 km and find that its slope changes several times as a function of radius before approaching the expected value for an equilibrium collisional cascade of material strength dominated bodies for R {approx}< 0.1 km. Compared to a single power-law size distribution that would span the whole range from 0.01 km to 30 km, we find in general a strong deficit of bodies around R {approx} 10 km and a strong excess of bodies around 2 km in radius. This deficit and excess of bodies are caused by the planetesimal size distribution left over from the runaway growth phase, which left most of the initial mass in small planetesimals while only a small fraction of the total mass is converted into large protoplanets. This excess mass in small planetesimals leaves a permanent signature in the size distribution of small bodies that is not erased after 4.5 Gyr of collisional evolution. Observations of the small Kuiper Belt Object (KBO) size distribution can therefore test if large KBOs grew as a result of runaway growth and constrained the initial planetesimal sizes. We find that results from

  17. Remote sensing of floe size distribution and surface topography

    NASA Technical Reports Server (NTRS)

    Rothrock, D. A.; Thorndike, A. S.

    1984-01-01

    Floe size can be measured by several properties p- for instance, area or mean caliper diameter. Two definitions of floe size distribution seem particularly useful. F(p), the fraction of area covered by floes no smaller than p; and N(p), the number of floes per unit area no smaller than p. Several summertime distributions measured are a graph, their slopes range from -1.7 to -2.5. The variance of an estimate is also calculated.

  18. Determination of lateral size distribution of type-II ZnTe/ZnSe stacked submonolayer quantum dots via spectral analysis of optical signature of the Aharanov-Bohm excitons

    SciTech Connect

    Ji, Haojie; Dhomkar, Siddharth; Roy, Bidisha; Kuskovsky, Igor L.; Shuvayev, Vladimir; Deligiannakis, Vasilios; Tamargo, Maria C.; Ludwig, Jonathan; Smirnov, Dmitry; Wang, Alice

    2014-10-28

    For submonolayer quantum dot (QD) based photonic devices, size and density of QDs are critical parameters, the probing of which requires indirect methods. We report the determination of lateral size distribution of type-II ZnTe/ZnSe stacked submonolayer QDs, based on spectral analysis of the optical signature of Aharanov-Bohm (AB) excitons, complemented by photoluminescence studies, secondary-ion mass spectroscopy, and numerical calculations. Numerical calculations are employed to determine the AB transition magnetic field as a function of the type-II QD radius. The study of four samples grown with different tellurium fluxes shows that the lateral size of QDs increases by just 50%, even though tellurium concentration increases 25-fold. Detailed spectral analysis of the emission of the AB exciton shows that the QD radii take on only certain values due to vertical correlation and the stacked nature of the QDs.

  19. Size-biased distributions in the generalized beta distribution family, with applications to forestry

    Treesearch

    Mark J. Ducey; Jeffrey H. Gove

    2015-01-01

    Size-biased distributions arise in many forestry applications, as well as other environmental, econometric, and biomedical sampling problems. We examine the size-biased versions of the generalized beta of the first kind, generalized beta of the second kind and generalized gamma distributions. These distributions include, as special cases, the Dagum (Burr Type III),...

  20. Estimation and applications of size-biased distributions in forestry

    Treesearch

    Jeffrey H. Gove

    2003-01-01

    Size-biased distributions arise naturally in several contexts in forestry and ecology. Simple power relationships (e.g. basal area and diameter at breast height) between variables are one such area of interest arising from a modelling perspective. Another, probability proportional to size PPS) sampling, is found in the most widely used methods for sampling standing or...

  1. Estimation and applications of size-based distributions in forestry

    Treesearch

    Jeffrey H. Gove

    2003-01-01

    Size-based distributions arise in several contexts in forestry and ecology. Simple power relationships (e.g., basal area and diameter at breast height) between variables are one such area of interest arising from a modeling perspective. Another, probability proportional to size sampline (PPS), is found in the most widely used methods for sampling standing or dead and...

  2. Machine vision based particle size and size distribution determination of airborne dust particles of wood and bark pellets

    SciTech Connect

    Igathinathane, C; Pordesimo, L.O.

    2009-08-01

    Dust management strategies in industrial environment, especially of airborne dust, require quantification and measurement of size and size distribution of the particles. Advanced specialized instruments that measure airborne particle size and size distribution apply indirect methods that involve light scattering, acoustic spectroscopy, and laser diffraction. In this research, we propose a simple and direct method of airborne dust particle dimensional measurement and size distribution analysis using machine vision. The method involves development of a user-coded ImageJ plugin that measures particle length and width and analyzes size distribution of particles based on particle length from high-resolution scan images. Test materials were airborne dust from soft pine wood sawdust pellets and ground pine tree bark pellets. Subsamples prepared by dividing the actual dust using 230 mesh (63 m) sieve were analyzed as well. A flatbed document scanner acquired the digital images of the dust particles. Proper sampling, layout of dust particles in singulated arrangement, good contrast smooth background, high resolution images, and accurate algorithm are essential for reliable analysis. A halo effect around grey-scale images ensured correct threshold limits. The measurement algorithm used Feret s diameter for particle length and pixel-march technique for particle width. Particle size distribution was analyzed in a sieveless manner after grouping particles according to their distinct lengths, and several significant dimensions and parameters of particle size distribution were evaluated. Results of the measurement and analysis were presented in textual and graphical formats. The developed plugin was evaluated to have a dimension measurement accuracy in excess of 98.9% and a computer speed of analysis of <8 s/image. Arithmetic mean length of actual wood and bark pellets airborne dust particles were 0.1138 0.0123 and 0.1181 0.0149 mm, respectively. The airborne dust particles of

  3. Phase-transfer based size refining of metal nanoparticles from arbitrary particle size distributions.

    PubMed

    Liu, Hui; Qu, Jianglan; Ye, Feng; Wang, Caixia; Yang, Jun

    2013-02-01

    The size-dependent phase-transfer property of metal nanoparticles is used to develop a simple experimental procedure that can effectively refine the particle size from colloidal solutions prepared by wet-chemistry. The protocol calls for firstly the mixing of the metal hydrosol with an ethanol solution of dodecylamine, and then the extraction of the dodecylamine-stabilized metal nanoparticles into toluene. This method offers an effective approach to prepare metal nanoparticles with narrow size distribution from an arbitrary particle size distribution.

  4. Strategic Petroleum Reserve: Analysis of size options

    SciTech Connect

    Not Available

    1990-02-01

    This report presents the results of the deliberations of the interagency group formed to study the costs and benefits of expanding the size of the SPR. The study concentrated on severe oil supply disruptions involving sharp reductions in world oil production that were 2 to 4 times larger than the largest 1970s interruption. The disruption sizes and estimated probability of occurrence of these scenarios were supplied by the CIA. The most critical part of the CIA's analysis was the assessment of likelihood of these cases occurring. The CIA approached the likelihood problem by combining an examination of past oil supply disruptions with qualitative analysis of important oil market and regional trends. The study group then used statistical techniques and probability distributions to synthesize the historical data with CIA evaluations of as yet unobserved events. The SPR size study assumed direct purchases of SPR oil and did not assume the use of alternative financing mechanisms. Members of the working group with foreign policy and national security responsibilities provided an in-depth review of strategic considerations affecting SPR size. A number of prior studies, some classified, have addressed the strategic importance and insurance value of the SPR to the US and its allies. The results of these studies have also been incorporated in the current effort. 10 refs., 5 figs.

  5. Determination of particle size distributions from acoustic wave propagation measurements

    SciTech Connect

    Spelt, P.D.; Norato, M.A.; Sangani, A.S.; Tavlarides, L.L.

    1999-05-01

    The wave equations for the interior and exterior of the particles are ensemble averaged and combined with an analysis by Allegra and Hawley [J. Acoust. Soc. Am. {bold 51}, 1545 (1972)] for the interaction of a single particle with the incident wave to determine the phase speed and attenuation of sound waves propagating through dilute slurries. The theory is shown to compare very well with the measured attenuation. The inverse problem, i.e., the problem of determining the particle size distribution given the attenuation as a function of frequency, is examined using regularization techniques that have been successful for bubbly liquids. It is shown that, unlike the bubbly liquids, the success of solving the inverse problem is limited since it depends strongly on the nature of particles and the frequency range used in inverse calculations. {copyright} {ital 1999 American Institute of Physics.}

  6. Sample sizes and model comparison metrics for species distribution models

    Treesearch

    B.B. Hanberry; H.S. He; D.C. Dey

    2012-01-01

    Species distribution models use small samples to produce continuous distribution maps. The question of how small a sample can be to produce an accurate model generally has been answered based on comparisons to maximum sample sizes of 200 observations or fewer. In addition, model comparisons often are made with the kappa statistic, which has become controversial....

  7. A comprehensive physicochemical, thermal, and spectroscopic characterization of zinc (II) chloride using X-ray diffraction, particle size distribution, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis, ultraviolet-visible, and Fourier transform-infrared spectroscopy

    PubMed Central

    Trivedi, Mahendra Kumar; Sethi, Kalyan Kumar; Panda, Parthasarathi; Jana, Snehasis

    2017-01-01

    Objective: Zinc chloride is an important inorganic compound used as a source of zinc and has other numerous industrial applications. Unfortunately, it lacks reliable and accurate physicochemical, thermal, and spectral characterization information altogether. Hence, the authors tried to explore in-depth characterization of zinc chloride using the modern analytical technique. Materials and Methods: The analysis of zinc chloride was performed using powder X-ray diffraction (PXRD), particle size distribution, differential scanning calorimetry (DSC), thermogravimetric analysis/differential thermogravimetric analysis (TGA/DTG), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform-infrared (FT-IR) analytical techniques. Results: The PXRD patterns showed well-defined, narrow, sharp, and the significant peaks. The crystallite size was found in the range of 14.70–55.40 nm and showed average crystallite size of 41.34 nm. The average particle size was found to be of 1.123 (d10), 3.025 (d50), and 6.712 (d90) μm and average surface area of 2.71 m2/g. The span and relative span values were 5.849 μm and 1.93, respectively. The DSC thermogram showed a small endothermic inflation at 308.10°C with the latent heat (ΔH) of fusion 28.52 J/g. An exothermic reaction was observed at 449.32°C with the ΔH of decomposition 66.10 J/g. The TGA revealed two steps of the thermal degradation and lost 8.207 and 89.72% of weight in the first and second step of degradation, respectively. Similarly, the DTG analysis disclosed Tmax at 508.21°C. The UV-vis spectrum showed absorbance maxima at 197.60 nm (λmax), and FT-IR spectrum showed a peak at 511/cm might be due to the Zn–Cl stretching. Conclusions: These in-depth, comprehensive data would be very much useful in all stages of nutraceuticals/pharmaceuticals formulation research and development and other industrial applications. PMID:28405577

  8. A comprehensive physicochemical, thermal, and spectroscopic characterization of zinc (II) chloride using X-ray diffraction, particle size distribution, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis, ultraviolet-visible, and Fourier transform-infrared spectroscopy.

    PubMed

    Trivedi, Mahendra Kumar; Sethi, Kalyan Kumar; Panda, Parthasarathi; Jana, Snehasis

    2017-01-01

    Zinc chloride is an important inorganic compound used as a source of zinc and has other numerous industrial applications. Unfortunately, it lacks reliable and accurate physicochemical, thermal, and spectral characterization information altogether. Hence, the authors tried to explore in-depth characterization of zinc chloride using the modern analytical technique. The analysis of zinc chloride was performed using powder X-ray diffraction (PXRD), particle size distribution, differential scanning calorimetry (DSC), thermogravimetric analysis/differential thermogravimetric analysis (TGA/DTG), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform-infrared (FT-IR) analytical techniques. The PXRD patterns showed well-defined, narrow, sharp, and the significant peaks. The crystallite size was found in the range of 14.70-55.40 nm and showed average crystallite size of 41.34 nm. The average particle size was found to be of 1.123 (d10), 3.025 (d50), and 6.712 (d90) μm and average surface area of 2.71 m(2)/g. The span and relative span values were 5.849 μm and 1.93, respectively. The DSC thermogram showed a small endothermic inflation at 308.10°C with the latent heat (ΔH) of fusion 28.52 J/g. An exothermic reaction was observed at 449.32°C with the ΔH of decomposition 66.10 J/g. The TGA revealed two steps of the thermal degradation and lost 8.207 and 89.72% of weight in the first and second step of degradation, respectively. Similarly, the DTG analysis disclosed Tmax at 508.21°C. The UV-vis spectrum showed absorbance maxima at 197.60 nm (λmax), and FT-IR spectrum showed a peak at 511/cm might be due to the Zn-Cl stretching. These in-depth, comprehensive data would be very much useful in all stages of nutraceuticals/pharmaceuticals formulation research and development and other industrial applications.

  9. The Seasonal Evolution of Sea Ice Floe Size Distribution

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. “The Seasonal Evolution of Sea Ice Floe Size Distribution...This work was motivated by the desire to improve the understanding of processes governing the evolution of the marginal ice zone that forms...seasonally in the southern Beaufort and Chukchi Seas region. OBJECTIVES The objective of this work was to determine the seasonal evolution of the

  10. Airborne Particle Size Distribution Measurements at USDOE Fernald

    SciTech Connect

    Harley, N.H.; Chittaporn, P.; Heikkinen, M.; Medora, R.; Merrill, R.

    2003-03-27

    There are no long term measurements of the particle size distribution and concentration of airborne radionuclides at any USDOE facility except Fernald. Yet the determinant of lung dose is the particle size, determining the airway and lower lung deposition. Beginning in 2000, continuous (6 to 8 weeks) measurements of the aerosol particle size distribution have been made with a miniature sampler developed under EMSP. Radon gas decays to a chain of four short lived solid radionuclides that attach immediately to the resident atmospheric aerosol. These in turn decay to long lived polonium 210. Alpha emitting polonium is a tracer for any atmospheric aerosol. Six samplers at Fernald and four at QC sites in New Jersey show a difference in both polonium concentration and size distribution with the winter measurements being higher/larger than summer by almost a factor of two at all locations. EMSP USDOE Contract DE FG07 97ER62522.

  11. Bubble size distribution in a laboratory-scale electroflotation study.

    PubMed

    Alam, Raquibul; Shang, Julie Q; Khan, Adnan Hossain

    2017-04-01

    The performance of electroflotation (EF) is strongly influenced by the size of O2 and H2 bubbles. Therefore, in this study, the bubble sizes are measured in a lab-scale EF cell using a high-speed camera. The mean bubble size is found to vary in the range of 32.7-68.6 μm under different operating conditions. This study shows that the electrode material, current density, water pH, ionic strength, and frother (Tennafroth 250) concentration are important factors in controlling the bubble size. Furthermore, four mathematical distributions (normal, log-normal, Weibull, and gamma distributions) are fitted to the experimental data, among which the log-normal distribution is found to be the best fit based on the lower Anderson-Darling (AD) value.

  12. Size distribution of microbubbles as a function of shell composition.

    PubMed

    Dicker, Stephen; Mleczko, Michał; Schmitz, Georg; Wrenn, Steven P

    2013-09-01

    The effect of modifying the shell composition of a population of microbubbles on their size demonstrated through experiment. Specifically, these variations include altering both the mole fraction and molecular weight of functionalized polymer, polyethylene glycol (PEG) in the microbubble phospholipid monolayer shell (1-15 mol% PEG, and 1000-5000 g/mole, respectively). The size distribution is measured with an unbiased image segmentation program written in MATLAB which identifies and sizes bubbles from micrographs. For a population of microbubbles with a shell composition of 5 mol% PEG2000, the mean diameter is 1.42 μm with a variance of 0.244 μm. For the remainder of the shell compositions studied herein, we find that the size distributions do not show a statistically significant correlation to either PEG molecular weight or mole fraction. All the measured distributions are nearly Gaussian in shape and have a monomodal peak.

  13. Characterizations of particle size distribution in Guangzhou during dry season

    NASA Astrophysics Data System (ADS)

    Li, Fei

    2017-04-01

    The relationship of ambient aerosol and visibility deterioration over Pearl River Delta(PRD) have attached more and more attentions in recent years. The extinction coefficient of ambient aerosol can be calculated with the Mie theory(N. Ma, 2014), which is based on a set of measured dry aerosol number size distribution, ambient relative humidity, aerosol hygroscopic growth factor, and the assumption of no activation. Using the parameters that can be easily measured would make the extinction coefficient of ambient aerosol calculation more widely available. PM2.5 (total mass concentration of dry aerosols with the aerodynamic diameter smaller than 2.5μm) measurements are widely applied in PRD, the aerosol concentrations could be estimated based on PM2.5 measurements and used to calculate the extinction. However, with different size distributions, aerosol with the same mass concentration may have different extinction coefficients. Ignoring the variations of the shapes of aerosol size distributions may introduce an uncertainty in the calculation of aerosol extinction coefficient. In order to quantify this uncertainty, the historical data of aerosol size distribution need to be analyzed. In this paper, continuous measurements of particle number size distributions and PM2.5 were simultaneously performed at Guangzhou urban site from Nov. 2014 to Jan. 2015. The temporal and diurnal statistical results of dry seasons would be used in the calculation of aerosol extinction coefficient, and the extinction coefficients corresponding to a certain aerosol volume concentration and relative humidity are given in the form of probability distribution.

  14. Packing fraction of particles with lognormal size distribution

    NASA Astrophysics Data System (ADS)

    Brouwers, H. J. H.

    2014-05-01

    This paper addresses the packing and void fraction of polydisperse particles with a lognormal size distribution. It is demonstrated that a binomial particle size distribution can be transformed into a continuous particle-size distribution of the lognormal type. Furthermore, an original and exact expression is derived that predicts the packing fraction of mixtures of particles with a lognormal distribution, which is governed by the standard deviation, mode of packing, and particle shape only. For a number of particle shapes and their packing modes (close, loose) the applicable values are given. This closed-form analytical expression governing the packing fraction is thoroughly compared with empirical and computational data reported in the literature, and good agreement is found.

  15. Inferring Past Effective Population Size from Distributions of Coalescent Times

    PubMed Central

    Gattepaille, Lucie; Günther, Torsten; Jakobsson, Mattias

    2016-01-01

    Inferring and understanding changes in effective population size over time is a major challenge for population genetics. Here we investigate some theoretical properties of random-mating populations with varying size over time. In particular, we present an exact solution to compute the population size as a function of time, Ne(t), based on distributions of coalescent times of samples of any size. This result reduces the problem of population size inference to a problem of estimating coalescent time distributions. To illustrate the analytic results, we design a heuristic method using a tree-inference algorithm and investigate simulated and empirical population-genetic data. We investigate the effects of a range of conditions associated with empirical data, for instance number of loci, sample size, mutation rate, and cryptic recombination. We show that our approach performs well with genomic data (≥ 10,000 loci) and that increasing the sample size from 2 to 10 greatly improves the inference of Ne(t) whereas further increase in sample size results in modest improvements, even under a scenario of exponential growth. We also investigate the impact of recombination and characterize the potential biases in inference of Ne(t). The approach can handle large sample sizes and the computations are fast. We apply our method to human genomes from four populations and reconstruct population size profiles that are coherent with previous finds, including the Out-of-Africa bottleneck. Additionally, we uncover a potential difference in population size between African and non-African populations as early as 400 KYA. In summary, we provide an analytic relationship between distributions of coalescent times and Ne(t), which can be incorporated into powerful approaches for inferring past population sizes from population-genomic data. PMID:27638421

  16. Cell-size distribution in epithelial tissue formation and homeostasis.

    PubMed

    Puliafito, Alberto; Primo, Luca; Celani, Antonio

    2017-03-01

    How cell growth and proliferation are orchestrated in living tissues to achieve a given biological function is a central problem in biology. During development, tissue regeneration and homeostasis, cell proliferation must be coordinated by spatial cues in order for cells to attain the correct size and shape. Biological tissues also feature a notable homogeneity of cell size, which, in specific cases, represents a physiological need. Here, we study the temporal evolution of the cell-size distribution by applying the theory of kinetic fragmentation to tissue development and homeostasis. Our theory predicts self-similar probability density function (PDF) of cell size and explains how division times and redistribution ensure cell size homogeneity across the tissue. Theoretical predictions and numerical simulations of confluent non-homeostatic tissue cultures show that cell size distribution is self-similar. Our experimental data confirm predictions and reveal that, as assumed in the theory, cell division times scale like a power-law of the cell size. We find that in homeostatic conditions there is a stationary distribution with lognormal tails, consistently with our experimental data. Our theoretical predictions and numerical simulations show that the shape of the PDF depends on how the space inherited by apoptotic cells is redistributed and that apoptotic cell rates might also depend on size. © 2017 The Author(s).

  17. Critical Initial Flaw Size Analysis

    NASA Technical Reports Server (NTRS)

    Dawicke, David S.; Raju, Ivatury S.; Cheston, Derrick J.

    2008-01-01

    An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). The USS consists of several "tuna can" segments that are approximately 216 inches in diameter, 115 inches tall, and 0.5 inches thick. A 6 inch wide by 1 inch thick flange is welded to the skin and is used to fasten adjacent tuna cans. A schematic of a "tuna can" and the location of the flange-to-skin weld are shown in Figure 1. Gussets (shown in yellow in Figure 1) are welded to the skin and flange every 10 degrees around the circumference of the "tuna can". The flange-to-skin weld is a flux core butt weld with a fillet weld on the inside surface, as illustrated in Figure 2. The welding process may create loss of fusion defects in the weld that could develop into fatigue cracks and jeopardize the structural integrity of the Ares I-X vehicle. The CIFS analysis was conducted to determine the largest crack in the weld region that will not grow to failure within 4 lifetimes, as specified by NASA standard 5001 & 5019 [1].

  18. Crater size distributions on Ganymede and Callisto: fundamental issues

    NASA Astrophysics Data System (ADS)

    Wagner, Roland; Schmedemann, Nico; Werner, Stefanie; Ivanov, Boris; Stephan, Katrin; Jaumann, Ralf

    2015-04-01

    Crater size distributions on the two largest Jovian satellites Ganymede and Callisto and the origin of impactors are subject of intense and controversial debates. In this paper, we reinvestigate crater size distributions measured in surface units derived from a recently published global geologic map, based on Voyager and Galileo SSI images at a scale of 1 km/pxl (Collins G. C. et al. (2013), U. S. Geol. Surv., Sci. Inv. Map 3237). These units are used as a context to units mapped in more detail at higher resolution in Galileo SSI images. We focus on the following fundamental issues: (1) Similarity between shapes of crater distributions on the Galilean satellites and on inner solar system bodies; (2) production versus equilibrium distributions; (3) apex/antapex variations in crater distributions. First, our results show a strong similarity in shape between the crater distributions on the most densely cratered regions on Ganymede and Callisto with those in the lunar highlands. We conclude that the shape of the crater distributions on these two Jovian satellites implies the craters were preferentially formed from members of a collisionally evolved projectile family, derived either from Main Belt asteroids as candidates of impactors on the Jovian satellites, or from projectiles stemming from the outer solar system which have undergone collisional evolution, resulting in a size distribution similar to those of Main Belt asteroids. Second, the complex shape of the crater distributions on Ganymede and Callisto indicates they are mostly production distributions and can be used to infer the underlying shape of the projectile size distribution. Locally, equilibrium distributions occur, especially at smaller sub-kilometer diameters. Third, the most densely cratered regions on both satellites do not show apex-antapex variations in crater frequency, as inferred for bodies from heliocentric orbits (e.g., Zahnle K. et al. (2003), Icarus 163, 263-289). This indicates that these

  19. Vesicle Size Distribution as a Novel Nuclear Forensics Tool.

    PubMed

    Donohue, Patrick H; Simonetti, Antonio

    The first nuclear bomb detonation on Earth involved a plutonium implosion-type device exploded at the Trinity test site (33°40'38.28″N, 106°28'31.44″W), White Sands Proving Grounds, near Alamogordo, New Mexico. Melting and subsequent quenching of the local arkosic sand produced glassy material, designated "Trinitite". In cross section, Trinitite comprises a thin (1-2 mm), primarily glassy surface above a lower zone (1-2 cm) of mixed melt and mineral fragments from the precursor sand. Multiple hypotheses have been put forward to explain these well-documented but heterogeneous textures. This study reports the first quantitative textural analysis of vesicles in Trinitite to constrain their physical and thermal history. Vesicle morphology and size distributions confirm the upper, glassy surface records a distinct processing history from the lower region, that is useful in determining the original sample surface orientation. Specifically, the glassy layer has lower vesicle density, with larger sizes and more rounded population in cross-section. This vertical stratigraphy is attributed to a two-stage evolution of Trinitite glass from quench cooling of the upper layer followed by prolonged heating of the subsurface. Defining the physical regime of post-melting processes constrains the potential for surface mixing and vesicle formation in a post-detonation environment.

  20. Vesicle Size Distribution as a Novel Nuclear Forensics Tool

    PubMed Central

    Simonetti, Antonio

    2016-01-01

    The first nuclear bomb detonation on Earth involved a plutonium implosion-type device exploded at the Trinity test site (33°40′38.28″N, 106°28′31.44″W), White Sands Proving Grounds, near Alamogordo, New Mexico. Melting and subsequent quenching of the local arkosic sand produced glassy material, designated “Trinitite”. In cross section, Trinitite comprises a thin (1–2 mm), primarily glassy surface above a lower zone (1–2 cm) of mixed melt and mineral fragments from the precursor sand. Multiple hypotheses have been put forward to explain these well-documented but heterogeneous textures. This study reports the first quantitative textural analysis of vesicles in Trinitite to constrain their physical and thermal history. Vesicle morphology and size distributions confirm the upper, glassy surface records a distinct processing history from the lower region, that is useful in determining the original sample surface orientation. Specifically, the glassy layer has lower vesicle density, with larger sizes and more rounded population in cross-section. This vertical stratigraphy is attributed to a two-stage evolution of Trinitite glass from quench cooling of the upper layer followed by prolonged heating of the subsurface. Defining the physical regime of post-melting processes constrains the potential for surface mixing and vesicle formation in a post-detonation environment. PMID:27658210

  1. Size Distributions of Solar Proton Events: Methodological and Physical Restrictions

    NASA Astrophysics Data System (ADS)

    Miroshnichenko, L. I.; Yanke, V. G.

    2016-12-01

    Based on the new catalogue of solar proton events (SPEs) for the period of 1997 - 2009 (Solar Cycle 23) we revisit the long-studied problem of the event-size distributions in the context of those constructed for other solar-flare parameters. Recent results on the problem of size distributions of solar flares and proton events are briefly reviewed. Even a cursory acquaintance with this research field reveals a rather mixed and controversial picture. We concentrate on three main issues: i) SPE size distribution for {>} 10 MeV protons in Solar Cycle 23; ii) size distribution of {>} 1 GV proton events in 1942 - 2014; iii) variations of annual numbers for {>} 10 MeV proton events on long time scales (1955 - 2015). Different results are critically compared; most of the studies in this field are shown to suffer from vastly different input datasets as well as from insufficient knowledge of underlying physical processes in the SPEs under consideration. New studies in this field should be made on more distinct physical and methodological bases. It is important to note the evident similarity in size distributions of solar flares and superflares in Sun-like stars.

  2. Extension of discrete tribocharging models to continuous size distributions

    NASA Astrophysics Data System (ADS)

    Carter, Dylan; Hartzell, Christine

    2017-01-01

    Triboelectric charging, the phenomenon by which electrical charge is exchanged during contact between two surfaces, has been known to cause significant charge separation in granular mixtures, even between chemically identical grains. This charging is a stochastic size-dependent process resulting from random collisions between grains. The prevailing models and experimental results suggest that, in most cases, larger grains in a mixture of dielectric grains acquire a positive charge, while smaller grains charge negatively. These models are typically restricted to mixtures of two discrete grain sizes, which are not representative of most naturally occurring granular mixtures, and neglect the effect of grain size on individual charging events. We have developed a model that predicts the average charge distribution in a granular mixture, for any continuous size distribution of dielectric grains of a single material. Expanding to continuous size distributions enables the prediction of charge separation in many natural granular phenomena, including terrestrial dust storms and industrial powder handling operations. The expanded model makes predictions about the charge distribution, including specific conditions under which the usual size-dependent polarity is reversed such that larger grains charge negatively.

  3. Determining Size Distribution at the Phoenix Landing Site

    NASA Astrophysics Data System (ADS)

    Mason, E. L.; Lemmon, M. T.

    2016-12-01

    Dust aerosols play a crucial role in determining atmospheric radiative heating on Mars through absorption and scattering of sunlight. How dust scatters and absorbs light is dependent on size, shape, composition, and quantity. Optical properties of the dust have been well constrained in the visible and near infrared wavelengths using various methods [Wolff et al. 2009, Lemmon et al. 2004]. In addition, the dust is nonspherical, and irregular shapes have shown to work well in determining effective particle size [Pollack et al. 1977]. Variance of the size distribution is less constrained but constitutes an important parameter in fully describing the dust. The Phoenix Lander's Surface Stereo Imager performed several cross-sky brightness surveys to determine the size distribution and scattering properties of dust in the wavelength range of 400 to 1000 nm. In combination with a single-layer radiative transfer model, these surveys can be used to help constrain variance of the size distribution. We will present a discussion of seasonal size distribution as it pertains to the Phoenix landing site.

  4. Modelling and validation of particle size distributions of supported nanoparticles using the pair distribution function technique

    DOE PAGES

    Gamez-Mendoza, Liliana; Terban, Maxwell W.; Billinge, Simon J. L.; ...

    2017-04-13

    The particle size of supported catalysts is a key characteristic for determining structure–property relationships. It is a challenge to obtain this information accurately and in situ using crystallographic methods owing to the small size of such particles (<5 nm) and the fact that they are supported. In this work, the pair distribution function (PDF) technique was used to obtain the particle size distribution of supported Pt catalysts as they grow under typical synthesis conditions. The PDF of Pt nanoparticles grown on zeolite X was isolated and refined using two models: a monodisperse spherical model (single particle size) and a lognormalmore » size distribution. The results were compared and validated using scanning transmission electron microscopy (STEM) results. Both models describe the same trends in average particle size with temperature, but the results of the number-weighted lognormal size distributions can also accurately describe the mean size and the width of the size distributions obtained from STEM. Since the PDF yields crystallite sizes, these results suggest that the grown Pt nanoparticles are monocrystalline. As a result, this work shows that refinement of the PDF of small supported monocrystalline nanoparticles can yield accurate mean particle sizes and distributions.« less

  5. Thresholded Power law Size Distributions of Instabilities in Astrophysics

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.

    2015-11-01

    Power-law-like size distributions are ubiquitous in astrophysical instabilities. There are at least four natural effects that cause deviations from ideal power law size distributions, which we model here in a generalized way: (1) a physical threshold of an instability; (2) incomplete sampling of the smallest events below a threshold x0; (3) contamination by an event-unrelated background xb; and (4) truncation effects at the largest events due to a finite system size. These effects can be modeled in the simplest terms with a “thresholded power law” distribution function (also called generalized Pareto [type II] or Lomax distribution), N(x){dx}\\propto {(x+{x}0)}-a{dx}, where x0 > 0 is positive for a threshold effect, while x0 < 0 is negative for background contamination. We analytically derive the functional shape of this thresholded power law distribution function from an exponential growth evolution model, which produces avalanches only when a disturbance exceeds a critical threshold x0. We apply the thresholded power law distribution function to terrestrial, solar (HXRBS, BATSE, RHESSI), and stellar flare (Kepler) data sets. We find that the thresholded power law model provides an adequate fit to most of the observed data. Major advantages of this model are the automated choice of the power law fitting range, diagnostics of background contamination, physical instability thresholds, instrumental detection thresholds, and finite system size limits. When testing self-organized criticality models that predict ideal power laws, we suggest including these natural truncation effects.

  6. Lognormal Behavior of the Size Distributions of Animation Characters

    NASA Astrophysics Data System (ADS)

    Yamamoto, Ken

    This study investigates the statistical property of the character sizes of animation, superhero series, and video game. By using online databases of Pokémon (video game) and Power Rangers (superhero series), the height and weight distributions are constructed, and we find that the weight distributions of Pokémon and Zords (robots in Power Rangers) follow the lognormal distribution in common. For the theoretical mechanism of this lognormal behavior, the combination of the normal distribution and the Weber-Fechner law is proposed.

  7. Rank-Size Distribution of Notes in Harmonic Music: Hierarchic Shuffling of Distributions

    NASA Astrophysics Data System (ADS)

    Del Río, Manuel Beltrán; Cocho, Germinal

    We trace the rank size distribution of notes in harmonic music, which on previous works we suggested was much better represented by the Two-parameter, first class Beta distribution than the customary power law, to the ranked mixing of distributions dictated by the harmonic and instrumental nature of the piece. The same representation is shown to arise in other fields by the same type of ranked shuffling of distributions. We include the codon content of intergenic DNA sequences and the ranked distribution of sizes of trees in a determined area as examples. We show that the fittings proposed increase their accuracy with the number of distributions that are mixed and ranked.

  8. Molecular theory of size exclusion chromatography for wide pore size distributions.

    PubMed

    Sepsey, Annamária; Bacskay, Ivett; Felinger, Attila

    2014-02-28

    Chromatographic processes can conveniently be modeled at a microscopic level using the molecular theory of chromatography. This molecular or microscopic theory is completely general; therefore it can be used for any chromatographic process such as adsorption, partition, ion-exchange or size exclusion chromatography. The molecular theory of chromatography allows taking into account the kinetics of the pore ingress and egress processes, the heterogeneity of the pore sizes and polymer polydispersion. In this work, we assume that the pore size in the stationary phase of chromatographic columns is governed by a wide lognormal distribution. This property is integrated into the molecular model of size exclusion chromatography and the moments of the elution profiles were calculated for several kinds of pore structure. Our results demonstrate that wide pore size distributions have strong influence on the retention properties (retention time, peak width, and peak shape) of macromolecules. The novel model allows us to estimate the real pore size distribution of commonly used HPLC stationary phases, and the effect of this distribution on the size exclusion process. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Global Patterns of City Size Distributions and Their Fundamental Drivers

    PubMed Central

    Decker, Ethan H.; Kerkhoff, Andrew J.; Moses, Melanie E.

    2007-01-01

    Urban areas and their voracious appetites are increasingly dominating the flows of energy and materials around the globe. Understanding the size distribution and dynamics of urban areas is vital if we are to manage their growth and mitigate their negative impacts on global ecosystems. For over 50 years, city size distributions have been assumed to universally follow a power function, and many theories have been put forth to explain what has become known as Zipf's law (the instance where the exponent of the power function equals unity). Most previous studies, however, only include the largest cities that comprise the tail of the distribution. Here we show that national, regional and continental city size distributions, whether based on census data or inferred from cluster areas of remotely-sensed nighttime lights, are in fact lognormally distributed through the majority of cities and only approach power functions for the largest cities in the distribution tails. To explore generating processes, we use a simple model incorporating only two basic human dynamics, migration and reproduction, that nonetheless generates distributions very similar to those found empirically. Our results suggest that macroscopic patterns of human settlements may be far more constrained by fundamental ecological principles than more fine-scale socioeconomic factors. PMID:17895975

  10. Production, depreciation and the size distribution of firms

    NASA Astrophysics Data System (ADS)

    Ma, Qi; Chen, Yongwang; Tong, Hui; Di, Zengru

    2008-05-01

    Many empirical researches indicate that firm size distributions in different industries or countries exhibit some similar characters. Among them the fact that many firm size distributions obey power-law especially for the upper end has been mostly discussed. Here we present an agent-based model to describe the evolution of manufacturing firms. Some basic economic behaviors are taken into account, which are production with decreasing marginal returns, preferential allocation of investments, and stochastic depreciation. The model gives a steady size distribution of firms which obey power-law. The effect of parameters on the power exponent is analyzed. The theoretical results are given based on both the Fokker-Planck equation and the Kesten process. They are well consistent with the numerical results.

  11. Initial drop size and velocity distributions for airblast coaxial atomizers

    NASA Technical Reports Server (NTRS)

    Eroglu, H.; Chigier, N.

    1991-01-01

    Phase Doppler measurements were used to determine initial drop size and velocity distributions after a complete disintegration of coaxial liquid jets. The Sauter mean diameter (SMD) distribution was found to be strongly affected by the structure and behavior of the preceding liquid intact jet. The axial measurement stations were determined from the photographs of the coaxial liquid jet at very short distances (1-2 mm) downstream of the observed break-up locations. Minimum droplet mean velocities were found at the center, and maximum velocities were near the spray boundary. Size-velocity correlations show that the velocity of larger drops did not change with drop size. Drop rms velocity distributions have double peaks whose radial positions coincide with the maximum mean velocity gradients.

  12. Aerosol size distribution at Nansen Ice Sheet Antarctica

    NASA Astrophysics Data System (ADS)

    Belosi, F.; Contini, D.; Donateo, A.; Santachiara, G.; Prodi, F.

    2012-04-01

    During austral summer 2006, in the framework of the XXII Italian Antarctic expedition of PNRA (Italian National Program for Research in Antarctica), aerosol particle number size distribution measurements were performed in the 10-500 range nm over the Nansen Ice Sheet glacier (NIS, 74°30' S, 163°27' E; 85 m a.s.l), a permanently iced branch of the Ross Sea. Observed total particle number concentrations varied between 169 and 1385 cm- 3. A monomodal number size distribution, peaking at about 70 nm with no variation during the day, was observed for continental air mass, high wind speed and low relative humidity. Trimodal number size distributions were also observed, in agreement with measurements performed at Aboa station, which is located on the opposite side of the Antarctic continent to the NIS. In this case new particle formation, with subsequent particle growth up to about 30 nm, was observed even if not associated with maritime air masses.

  13. Recovering 3D particle size distributions from 2D sections

    NASA Astrophysics Data System (ADS)

    Cuzzi, Jeffrey N.; Olson, Daniel M.

    2017-03-01

    We discuss different ways to convert observed, apparent particle size distributions from 2D sections (thin sections, SEM maps on planar surfaces, etc.) into true 3D particle size distributions. We give a simple, flexible, and practical method to do this; show which of these techniques gives the most faithful conversions; and provide (online) short computer codes to calculate both 2D-3D recoveries and simulations of 2D observations by random sectioning. The most important systematic bias of 2D sectioning, from the standpoint of most chondrite studies, is an overestimate of the abundance of the larger particles. We show that fairly good recoveries can be achieved from observed size distributions containing 100-300 individual measurements of apparent particle diameter.

  14. Initial drop size and velocity distributions for airblast coaxial atomizers

    NASA Technical Reports Server (NTRS)

    Eroglu, H.; Chigier, N.

    1991-01-01

    Phase Doppler measurements were used to determine initial drop size and velocity distributions after a complete disintegration of coaxial liquid jets. The Sauter mean diameter (SMD) distribution was found to be strongly affected by the structure and behavior of the preceding liquid intact jet. The axial measurement stations were determined from the photographs of the coaxial liquid jet at very short distances (1-2 mm) downstream of the observed break-up locations. Minimum droplet mean velocities were found at the center, and maximum velocities were near the spray boundary. Size-velocity correlations show that the velocity of larger drops did not change with drop size. Drop rms velocity distributions have double peaks whose radial positions coincide with the maximum mean velocity gradients.

  15. Measurement of the (212)Pb particle size distribution indoors.

    PubMed

    Zhang, L; Guo, Q; Zhuo, W

    2010-10-01

    A new device has been developed for the measurement of the (212)Pb particle size distribution indoors. This device consists of two wire screens and a back-up filter with a diameter of 2.0 cm. The sampling flow rate is typically 3.0 l min(-1). After 3-h sampling time and 6-h waiting time, a CR-39 detector is used for the registration of the alpha particles from the (212)Pb, deposited on the wire screens and the filter, respectively. It appears clear from field measurements that there are no appreciable differences among the particle size distributions from different dwellings within the same location and under the same climate conditions. However, the (212)Pb particle size distributions from the countryside dwellings have different results from those of the city dwellings.

  16. Dynamic Scaling of Island-size Distribution on Anisotropic Surfaces

    NASA Astrophysics Data System (ADS)

    Li, Maozhi; Wang, E. G.; Liu, Banggui; Zhang, Zhenyu

    2002-03-01

    Dynamic scaling of island-size distribution on isotropic and anisotropic surfaces in submonolayer growth is systematically studied using kinetic Monte Carlo simulations. It is found that the island-size distribution in anisotropic submonolayer growth exhibits a general dynamic scaling behavior. An analytic expression is proposed for the scaling function, and is compared with the simulation results. This scaling function not only improves previous results for the isotropic growth (1), but also describes the scaling behavior of the island-size distribution in anisotropic submonolayer growth very well (2). 1. J. G. Amar and F. Family, Phys. Rev. Lett. 74, 2066 (1995). 2. M. Z. Li, E. G. Wang, B. G. Liu, and Z. Y. Zhang, Phys. Rev. Lett. (submitted).

  17. The Size Frequency Distribution of Small Main-Belt Asteroids

    NASA Technical Reports Server (NTRS)

    Burt, Brian J.; Trilling, David E.; Hines, Dean C.; Stapelfeldt, Karl R.; Rebull, Luisa M.; Fuentes, Cesar I.; Hulsebus, Alan

    2012-01-01

    The asteroid size distribution informs us about the formation and composition of the Solar System. We build on our previous work in which we harvest serendipitously observed data of the Taurus region and measure the brightness and size distributions of Main-belt asteroids. This is accomplished with the highly sensitive MIPS 24 micron channel. We expect to catalog 104 asteroids, giving us a statistically significant data set. Results from this investigation will allow us to characterize the total population of small, Main-belt asteroids. Here we will present new results on the completeness of our study; on the presence of size distribution variations with inclination and radial distance in the belt; and early result on other archival fields.

  18. Endogenic craters on basaltic lava flows - Size frequency distributions

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Gault, D. E.

    1979-01-01

    Circular crater forms, termed collapse depressions, which occur on many basalt flows on the earth have also been detected on the moon and Mars and possibly on Mercury and Io. The admixture of collapse craters with impact craters would affect age determinations of planetary surface units based on impact crater statistics by making them appear anomalously old. In the work described in the present paper, the techniques conventionally used in planetary crater counting were applied to the determination of the size range and size frequency distribution of collapse craters on lava flows in Idaho, California, and New Mexico. Collapse depressions range in size from 3 to 80 m in diameter; their cumulative size distributions are similar to those of small impact craters on the moon.

  19. Guest Editorial Particle Sizing And Spray Analysis

    NASA Astrophysics Data System (ADS)

    Chigier, Norman; Stewart, Gerald

    1984-10-01

    The measurement of particle size and velocity in particle laden flows is a subject of interest in a variety of industrial applications. In combustion systems for electricity generation, industrial processes and heating, and transportation, where liquid and solid fuels are injected into air streams for burning in furnaces, boilers, and gas turbine and diesel engines, the initial size and velocity distributions of particles are determining factors in the overall combustion efficiency and the emission of pollutants and particulates. In the design of injectors and burners for the atomization of liquid fuels, a great deal of attention is being focused on developing instrumentation for the accurate measurement of size and velocity distributions in sprays as a function of space and time. Most recent advances in optical engineering techniques using lasers for particle measurement have focused on detailed spray characterization, where there is a major concern with spherical liquid droplets within the size range of 1 to 500 μm in diameter, with droplet velocities within the range of 1 to 100 m/s, and the requirement for making in situ measurements of moving particles by nonintrusive optical probes. The instruments being developed for spray analysis have much wider applications. These include measurement in particle laden flows encountered in a variety of industrial processes with solid particles in gas and liquid streams and liquid particles in gas streams. Sprays used in agriculture, drying, food processing, coating of materials, chemical processing, clean rooms, pharmaceuticals, plasma spraying, and icing wind tunnels are examples of systems for which information is being sought on particle and fluid dynamic interactions in which there is heat, mass, and momentum transfer in turbulent reacting flows.

  20. Particle size distribution and particle size-related crystalline silica content in granite quarry dust.

    PubMed

    Sirianni, Greg; Hosgood, Howard Dean; Slade, Martin D; Borak, Jonathan

    2008-05-01

    Previous studies indicate that the relationship between empirically derived particle counts, particle mass determinations, and particle size-related silica content are not constant within mines or across mine work tasks. To better understand the variability of particle size distributions and variations in silica content by particle size in a granite quarry, exposure surveys were conducted with side-by-side arrays of four closed face cassettes, four cyclones, four personal environmental monitors, and a real-time particle counter. In general, the proportion of silica increased as collected particulate size increased, but samples varied in an inconstant way. Significant differences in particle size distributions were seen depending on the extent of ventilation and the nature and activity of work performed. Such variability raises concerns about the adequacy of silica exposure assessments based on only limited numbers of samples or short-term samples.

  1. General expression for the component size distribution in infinite configuration networks

    NASA Astrophysics Data System (ADS)

    Kryven, Ivan

    2017-05-01

    In the infinite configuration network the links between nodes are assigned randomly with the only restriction that the degree distribution has to match a predefined function. This work presents a simple equation that gives for an arbitrary degree distribution the corresponding size distribution of connected components. This equation is suitable for fast and stable numerical computations up to the machine precision. The analytical analysis reveals that the asymptote of the component size distribution is completely defined by only a few parameters of the degree distribution: the first three moments, scale, and exponent (if applicable). When the degree distribution features a heavy tail, multiple asymptotic modes are observed in the component size distribution that, in turn, may or may not feature a heavy tail.

  2. Influence of multidroplet size distribution on icing collection efficiency

    NASA Technical Reports Server (NTRS)

    Chang, H.-P.; Kimble, K. R.; Frost, W.; Shaw, R. J.

    1983-01-01

    Calculation of collection efficiencies of two-dimensional airfoils for a monodispersed droplet icing cloud and a multidispersed droplet is carried out. Comparison is made with the experimental results reported in the NACA Technical Note series. The results of the study show considerably improved agreement with experiment when multidroplet size distributions are employed. The study then investigates the effect of collection efficiency on airborne particle droplet size sampling instruments. The biased effect introduced due to sampling from different collection volumes is predicted.

  3. The Size Distribution of Jupiter-Family Comet Nuclei

    NASA Astrophysics Data System (ADS)

    Weissman, Paul R.; Snodgrass, C.; Fitzsimmons, A.; Lowry, S. C.

    2009-09-01

    We present an updated size distribution for the nuclei of Jupiter-Family Comets, based on observations of nuclei at large heliocentric distances. The data set used includes our own recently published work and that of others published since the comprehensive review by Lamy et al. (2004, in Comets II), in addition to older measurements from the refereed literature that were included in that compilation. We apply a new approach to make a rigorous assessment of the uncertainty on the size distribution power law slope, taking into account all unknown factors and sources of uncertainty. We include: 1) the uncertainty on the original photometry; 2) the difference between the measured effective radius from snap-shot observations and the mean effective radius for observations at unknown rotational phase of a nucleus with unknown pole orientation and axial ratio; 3) the unknown solar phase function; and 4) the unknown albedo. We use a Monte Carlo technique to look at how the size distribution changes when allowing individual size measurements to vary within these uncertainties. We find the cumulative size distribution can be fit by a power law, N( > r) r^{-a}, where r is the radius and the slope, a = 1.86 ± 0.15. This work was funded in part by the NASA Planetary Astronomy Program and was performed in part at the Jet Propulsion Laboratory under contract with NASA.

  4. Three optical methods for remotely measuring aerosol size distributions.

    NASA Technical Reports Server (NTRS)

    Reagan, J. A.; Herman, B. M.

    1971-01-01

    Three optical probing methods for remotely measuring atmospheric aerosol size distributions are discussed and contrasted. The particular detection methods which are considered make use of monostatic lidar (laser radar), bistatic lidar, and solar radiometer sensing techniques. The theory of each of these measurement techniques is discussed briefly, and the necessary constraints which must be applied to obtain aerosol size distribution information from such measurements are pointed out. Theoretical and/or experimental results are also presented which demonstrate the utility of the three proposed probing methods.

  5. Size distribution of Portuguese firms between 2006 and 2012

    NASA Astrophysics Data System (ADS)

    Pascoal, Rui; Augusto, Mário; Monteiro, A. M.

    2016-09-01

    This study aims to describe the size distribution of Portuguese firms, as measured by annual sales and total assets, between 2006 and 2012, giving an economic interpretation for the evolution of the distribution along the time. Three distributions are fitted to data: the lognormal, the Pareto (and as a particular case Zipf) and the Simplified Canonical Law (SCL). We present the main arguments found in literature to justify the use of distributions and emphasize the interpretation of SCL coefficients. Methods of estimation include Maximum Likelihood, modified Ordinary Least Squares in log-log scale and Nonlinear Least Squares considering the Levenberg-Marquardt algorithm. When applying these approaches to Portuguese's firms data, we analyze if the evolution of estimated parameters in both lognormal power and SCL is in accordance with the known existence of a recession period after 2008. This is confirmed for sales but not for assets, leading to the conclusion that the first variable is a best proxy for firm size.

  6. Consistent patterns of the size distribution of thermokarst lakes

    NASA Astrophysics Data System (ADS)

    Viktorov, A. S.; Kapralova, V. N.; Orlov, T. V.; Trapeznikova, O. N.; Arkhipova, M. V.; Berezin, P. V.; Zverev, A. V.; Panchenko, E. N.; Sadkov, S. A.

    2017-06-01

    The purpose of this work is to study empirically the patterns of size distribution of thermokarst lakes within lacustrine thermokarst plains. Investigations were performed at 16 sites with various geomorphological, geocryological, and physical geographical conditions (Kolyma Lowland, Western Siberia, Lena River valley, Alaska). The accordance of the distribution area with the lognormal and exponential laws, and the accordance of the average diameter distribution with the normal law have been tested; the tested laws of distribution resulted from previous investigations. The results have shown that the lognormal law of distribution of thermokarst lake areas is valid for the vast majority of cases, and the other types of distribution are inconsistent with empirical data. This evidence favors the development pattern for lacustrine thermokarst plains, when thermokarst processes started simultaneously and the rate of lake growth was proportional to the density of heat loss through the side surface.

  7. Effective scatterer diameter estimates for broad scatterer size distributions.

    PubMed

    Nordberg, Eric P; Hall, Timothy J

    2015-01-01

    Acoustic form factors have been used to model the frequency dependence of acoustic scattering in phantoms and tissues. This work demonstrates that a broad range of scatterer sizes, individually well represented by Faran theory or a Gaussian form factor, is not accurately described by a single effective scatterer from either of these models. Contributions from a distribution of discrete scatterer sizes for two different form factor functions (Gaussian form factors and scattering functions from Faran's theory) were calculated and linearly combined. Composite form factors created from Gaussian distributions of scatterer sizes centered at 50 µm with standard deviations of up to σ = 40 µm were fit to each scattering model between 2 and 12 MHz. Scatterer distributions were generated using one of two assumptions: the number density of the scatterer diameter distribution was Gaussian distributed, or the volume fraction of each scatterer diameter in the distribution was Gaussian distributed. Each simulated form factor was fit to a single-diameter form factor model for Gaussian and exponential form factors. The mean-squared error (MSE) between the composite simulated data and the best-fit single-diameter model was smaller with an exponential form factor model, compared with a Gaussian model, for distributions with standard deviations larger than 30% of the centroid value. In addition, exponential models were shown to have better ability to distinguish between Faran scattering model-based distributions with varying center diameters than the Gaussian form factor model. The evidence suggests that when little is known about the scattering medium, an exponential scattering model provides a better first approximation to the scattering correlation function for a broad distribution of spherically symmetric scatterers than when a Gaussian form factor model is assumed.

  8. Particle size distributions of several commonly used seeding aerosols

    NASA Technical Reports Server (NTRS)

    Crosswy, F. L.

    1985-01-01

    During the course of experimentation, no solid particle powder could be found which produced an aerosol with a narrow particle size distribution when fluidization was the only flow process used in producing the aerosol. The complication of adding particle size fractionation processes to the aerosol generation effort appears to be avoidable. In this regard, a simple sonic orifice is found to be effective in reducing the percentage of agglomerates in the several metal oxide powders tested. Marginally beneficial results are obtained for a 0.5/99.5 percent by weight mixture of the flow agent and metal oxide powder. However, agglomeration is observed to be enhanced when the flow agent percentage is increased to 5 percent. Liquid atomization using the Collison nebulizer as well as a version of the Laskin nozzle resulted in polydispersed aerosols with particle size distributions heavily weighted by the small particle end of the size spectrum. The aerosol particle size distributions produced by the vaporization/condensation seeder are closer to the ideal monodispersed aerosol than any of the other aerosols tested. In addition, this seeding approach affords a measure of control over particle size and particle production rate.

  9. Interpolation of the raindrop size distribution over a GPM-pixel-sized region.

    NASA Astrophysics Data System (ADS)

    Berne, A.; Raupach, T.

    2014-12-01

    The raindrop size distribution (DSD) is crucial information on the structure of rainfall. All bulk rainfall variables of interest can be derived as weighted moments of the DSD. Usually the DSD is measured at point locations using disdrometers. In some contexts, such as the investigation of scale-change effects, it would be useful to be able to interpolate the DSD across space between point measurements. Traditionally such studies are performed by interpolating bulk variables individually. Such an approach fails to take into account any interrelationships between the bulk variables and information is lost. We present a spatial interpolation method for the whole drop size distribution. Instead of using multivariate geostatistics, we use a principle component analysis (PCA) to identify orthogonal components of the DSD. These components are independent, and thus we can apply univariate geostatistics to each one individually. Interpolation is carried out using ordinary kriging. Once components are interpolated, the interpolation of the DSD can be recovered at any requested point by recombining and back-transforming the components. The advantages of the method are that the DSD is interpolated in full, the use of PCA allows us to control and quantify the amount of information loss that occurs, and relationships between any bulk variables are maintained through the process. An important feature of rainfall that is considered in the proposed interpolation method is the intermittency and its influence on the spatial distribution of raindrops. We have applied this technique to DSDs recorded at point locations in a GPM-pixel sized area in Ardèche, France in the framework of the HyMeX project. To test the results we use leave-one-out testing and compare to interpolation of individual bulk variables; the results are favourable. An investigation of the radar reflectivity to rain-rate (Z-R) relationship shows that our DSD interpolation technique maintains the relationships

  10. Size distribution of biogenic aerosol particles from the amazon basin

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Hansson, Hans-Christen

    The size distribution and elemental composition of natural background aerosol particles from the tropical rain forest of the Amazon Basin were measured. A 45 m high tower installed in an undisturbed forest near Manaus was used and aerosol was sampled in three levels of the tower. Single orifice Batelle-type cascade impactors with 5 stages and backup filter were used. A total of 50 complete cascade impactor sets was sampled in April and May 1987, during the wet season, when no forest burning occurs. Particle-induced X-ray emission (PIXE) was used to measure elemental concentrations of 20 elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr and Pb). Absolute factor analysis was used to interpret the large data set of the trace element concentrations and to obtain quantitative elemental source profiles. The identified components in all size ranges comprise biogenic aerosol naturally released by the forest, mineral dust aerosol particles and sea salt. The elements associated with the biogenic component were potassium, phosphorus, sulphur, zinc, strontium and others in smaller proportions. The mineral dust component comprises most of the concentration of aluminium, silicon, calcium, titanium, manganese and iron. Chlorine was found to be associated with the aeolean dust component because of the long-range transport of Sahara dust over the Atlantic ocean, bringing Cl together with mineral dust particles. The size distribution of the elements associated with the windblown dust (Al, Si, Ca, Ti, Mn, Fe and Cl) shows in the coarse mode, with an average aerodynamic diameter of 4 μm. Two different biogenic aerosol components were observed. A fine mode component ( d50 ≈ 0.5 μm), characterised by the the elements S, Zn and Sr and the mode biogenic component ( d50 ≈ 3.0 μm) characterised by the presence of P, K, Cl and Sr. The coarse biogenic (P, K, Cl, Sr) component is predominant at ground level under the forest canopy. The fine mode biogenic

  11. Particle size distributions by transmission electron microscopy: an interlaboratory comparison case study

    PubMed Central

    Rice, Stephen B; Chan, Christopher; Brown, Scott C; Eschbach, Peter; Han, Li; Ensor, David S; Stefaniak, Aleksandr B; Bonevich, John; Vladár, András E; Hight Walker, Angela R; Zheng, Jiwen; Starnes, Catherine; Stromberg, Arnold; Ye, Jia; Grulke, Eric A

    2015-01-01

    This paper reports an interlaboratory comparison that evaluated a protocol for measuring and analysing the particle size distribution of discrete, metallic, spheroidal nanoparticles using transmission electron microscopy (TEM). The study was focused on automated image capture and automated particle analysis. NIST RM8012 gold nanoparticles (30 nm nominal diameter) were measured for area-equivalent diameter distributions by eight laboratories. Statistical analysis was used to (1) assess the data quality without using size distribution reference models, (2) determine reference model parameters for different size distribution reference models and non-linear regression fitting methods and (3) assess the measurement uncertainty of a size distribution parameter by using its coefficient of variation. The interlaboratory area-equivalent diameter mean, 27.6 nm ± 2.4 nm (computed based on a normal distribution), was quite similar to the area-equivalent diameter, 27.6 nm, assigned to NIST RM8012. The lognormal reference model was the preferred choice for these particle size distributions as, for all laboratories, its parameters had lower relative standard errors (RSEs) than the other size distribution reference models tested (normal, Weibull and Rosin–Rammler–Bennett). The RSEs for the fitted standard deviations were two orders of magnitude higher than those for the fitted means, suggesting that most of the parameter estimate errors were associated with estimating the breadth of the distributions. The coefficients of variation for the interlaboratory statistics also confirmed the lognormal reference model as the preferred choice. From quasi-linear plots, the typical range for good fits between the model and cumulative number-based distributions was 1.9 fitted standard deviations less than the mean to 2.3 fitted standard deviations above the mean. Automated image capture, automated particle analysis and statistical evaluation of the data and fitting coefficients provide a

  12. Particle size distributions by transmission electron microscopy: an interlaboratory comparison case study.

    PubMed

    Rice, Stephen B; Chan, Christopher; Brown, Scott C; Eschbach, Peter; Han, Li; Ensor, David S; Stefaniak, Aleksandr B; Bonevich, John; Vladár, András E; Hight Walker, Angela R; Zheng, Jiwen; Starnes, Catherine; Stromberg, Arnold; Ye, Jia; Grulke, Eric A

    2013-11-01

    This paper reports an interlaboratory comparison that evaluated a protocol for measuring and analysing the particle size distribution of discrete, metallic, spheroidal nanoparticles using transmission electron microscopy (TEM). The study was focused on automated image capture and automated particle analysis. NIST RM8012 gold nanoparticles (30 nm nominal diameter) were measured for area-equivalent diameter distributions by eight laboratories. Statistical analysis was used to (1) assess the data quality without using size distribution reference models, (2) determine reference model parameters for different size distribution reference models and non-linear regression fitting methods and (3) assess the measurement uncertainty of a size distribution parameter by using its coefficient of variation. The interlaboratory area-equivalent diameter mean, 27.6 nm ± 2.4 nm (computed based on a normal distribution), was quite similar to the area-equivalent diameter, 27.6 nm, assigned to NIST RM8012. The lognormal reference model was the preferred choice for these particle size distributions as, for all laboratories, its parameters had lower relative standard errors (RSEs) than the other size distribution reference models tested (normal, Weibull and Rosin-Rammler-Bennett). The RSEs for the fitted standard deviations were two orders of magnitude higher than those for the fitted means, suggesting that most of the parameter estimate errors were associated with estimating the breadth of the distributions. The coefficients of variation for the interlaboratory statistics also confirmed the lognormal reference model as the preferred choice. From quasi-linear plots, the typical range for good fits between the model and cumulative number-based distributions was 1.9 fitted standard deviations less than the mean to 2.3 fitted standard deviations above the mean. Automated image capture, automated particle analysis and statistical evaluation of the data and fitting coefficients provide a

  13. Size Evolution and Stochastic Models: Explaining Ostracod Size through Probabilistic Distributions

    NASA Astrophysics Data System (ADS)

    Krawczyk, M.; Decker, S.; Heim, N. A.; Payne, J.

    2014-12-01

    The biovolume of animals has functioned as an important benchmark for measuring evolution throughout geologic time. In our project, we examined the observed average body size of ostracods over time in order to understand the mechanism of size evolution in these marine organisms. The body size of ostracods has varied since the beginning of the Ordovician, where the first true ostracods appeared. We created a stochastic branching model to create possible evolutionary trees of ostracod size. Using stratigraphic ranges for ostracods compiled from over 750 genera in the Treatise on Invertebrate Paleontology, we calculated overall speciation and extinction rates for our model. At each timestep in our model, new lineages can evolve or existing lineages can become extinct. Newly evolved lineages are assigned sizes based on their parent genera. We parameterized our model to generate neutral and directional changes in ostracod size to compare with the observed data. New sizes were chosen via a normal distribution, and the neutral model selected new sizes differentials centered on zero, allowing for an equal chance of larger or smaller ostracods at each speciation. Conversely, the directional model centered the distribution on a negative value, giving a larger chance of smaller ostracods. Our data strongly suggests that the overall direction of ostracod evolution has been following a model that directionally pushes mean ostracod size down, shying away from a neutral model. Our model was able to match the magnitude of size decrease. Our models had a constant linear decrease while the actual data had a much more rapid initial rate followed by a constant size. The nuance of the observed trends ultimately suggests a more complex method of size evolution. In conclusion, probabilistic methods can provide valuable insight into possible evolutionary mechanisms determining size evolution in ostracods.

  14. Application of bag sampling technique for particle size distribution measurements.

    PubMed

    Mazaheri, M; Johnson, G R; Morawska, L

    2009-11-01

    Bag sampling techniques can be used to temporarily store the aerosol and therefore provide sufficient time to utilize sensitive but slow instrumental techniques for recording detailed particle size distributions. Laboratory based assessment of the method was conducted to examine size dependant deposition loss coefficients for aerosols held in Velostat bags conforming to a horizontal cylindrical geometry. Deposition losses of NaCl particles in the range of 10 nm to 160 nm were analysed in relation to the bag size, storage time, and sampling flow rate. Results of this study suggest that the bag sampling method is most useful for moderately short sampling periods of about 5 minutes.

  15. Size distributions of gold nanoclusters studied by liquid chromatography

    SciTech Connect

    WILCOXON,JESS P.; MARTIN,JAMES E.; PROVENCIO,PAULA P.

    2000-05-23

    The authors report high pressure liquid chromatography, (HPLC), and transmission electron microscopy, (TEM), studies of the size distributions of nanosize gold clusters dispersed in organic solvents. These metal clusters are synthesized in inverse micelles at room temperature and those investigated range in diameter from 1--10 nm. HPLC is sensitive enough to discern changes in hydrodynamic volume corresponding to only 2 carbon atoms of the passivating agent or metal core size changes of less than 4 {angstrom}. The authors have determined for the first time how the total cluster volume (metal core + passivating organic shell) changes with the size of the passivating agent.

  16. The size-distribution of Earth’s lakes

    PubMed Central

    Cael, B. B.; Seekell, D. A.

    2016-01-01

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth’s lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km2 are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes <8.5 km2 are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales. PMID:27388607

  17. Aerosol mobility imaging for rapid size distribution measurements

    SciTech Connect

    Wang, Jian; Hering, Susanne Vera; Spielman, Steven Russel; Kuang, Chongai

    2016-07-19

    A parallel plate dimensional electrical mobility separator and laminar flow water condensation provide rapid, mobility-based particle sizing at concentrations typical of the remote atmosphere. Particles are separated spatially within the electrical mobility separator, enlarged through water condensation, and imaged onto a CCD array. The mobility separation distributes particles in accordance with their size. The condensation enlarges size-separated particles by water condensation while they are still within the gap of the mobility drift tube. Once enlarged the particles are illuminated by a laser. At a pre-selected frequency, typically 10 Hz, the position of all of the individual particles illuminated by the laser are captured by CCD camera. This instantly records the particle number concentration at each position. Because the position is directly related to the particle size (or mobility), the particle size spectra is derived from the images recorded by the CCD.

  18. Particle Size Distribution in Saturn’s Ring C

    NASA Astrophysics Data System (ADS)

    Marouf, Essam A.; Wong, K.; French, R.; Rappaport, N.

    2012-10-01

    Information about particle sizes in Saturn’s rings is provided by two complementary types of Cassini radio occultation measurements. The first is differential extinction of three coherent sinusoidal signals transmitted by Cassini through the rings back to Earth (wavelength = 0.94, 3.6, and 13 cm, respectively). The differential measurements strongly constraint three parameters of an assumed power-law size distribution n(a) = n0 (a/a0)q, amin ≤ a ≤ amax: namely, the power law index q, the minimum radius amin, and reference abundance n0 at reference radius a0. The differential measurements are particularly sensitive to radii in the range 0.1 mm < a < 1 m. Complementing this capability, is a second type of measurements that is particularly sensitive to the larger radii 1 m < a < 20 m and their abundance. Signature of the collective near-forward scattering by these particles is captured in power spectrum measurements as broadened component of width, shape, and strength that depend on ring particle sizes, their spatial distribution, and observation geometry. Contributions of ring features of width as small several hundred kilometers can be identified and isolated in the measured spectra for a small subset of Cassini orbits of favorable geometry. We use three inverse scattering algorithms (Bayes, constrained linear inversion, generalized singular-value-decomposition) to recover the size distribution of particles of resolved ring features over the size range 1 m < a < 20 m without assuming an explicit size distribution model. We also investigate consistency of the results with a single power-law model extending over 0.1 mm < a < 20 m and implications to the spatial distribution of ring particles normal to the ring plane (vertical ring thickness). We present example results for selected features across Saturn’s Ring C where little evidence for gravitational wakes is present, hence the approaches above are applicable.

  19. THE SIZE-LUMINOSITY DISTRIBUTIONS OF LYMAN-BREAK GALAXIES

    NASA Astrophysics Data System (ADS)

    Huang, Kuang-Han; CANDELS Collaboration

    2014-01-01

    Lyman-break galaxies (LBGs) comprise the largest sample of star-forming galaxies at z>3 and are crucial to our understanding of galaxy formation and evolution. Their luminosity functions allow us to calculate the cosmic star formation history, and their sizes also provide valuable information about the angular momentum content of the galaxies and dark matter halos. However, due to surface brightness dimming effects, galaxies at high redshifts are especially susceptible to selection effects; it is important to understand the selection effects before we can draw conclusions from the statistics of LBG properties. In this work we will investigate the size--luminosity distribution of LBGs between 3 and 6 with careful modeling of selection effects and measurement errors of size and magnitude. Our modeling is more careful than previous studies because it is performed in the two-dimensional size--magnitude space. The results of this work show that (1) the effective radii of star-forming galaxies likely evolve as H(z)^{-2/3} at a fixed luminosity, (2) the widths of the LBG size distribution are larger than expected from the spin parameter distribution of dark matter halos, and (3) the size--luminosity relation slopes of LBGs are similar to those for late-type disk galaxies in the local universe. These results favor the disk formation theory put forward by Fall & Efstathiou (1980) if the majority of LBGs are disks, but more observational evidence is needed to confirm the kinematical structure of LBGs as well as to explain the widths of the size distribution.

  20. The Lunar Rock Size Frequency Distribution from Diviner Infrared Measurements

    NASA Astrophysics Data System (ADS)

    Elder, C. M.; Hayne, P. O.; Piqueux, S.; Bandfield, J.; Williams, J. P.; Ghent, R. R.; Paige, D. A.

    2016-12-01

    Knowledge of the rock size frequency distribution on a planetary body is important for understanding its geologic history and for selecting landing sites. The rock size frequency distribution can be estimated by counting rocks in high resolution images, but most bodies in the solar system have limited areas with adequate coverage. We propose an alternative method to derive and map rock size frequency distributions using multispectral thermal infrared data acquired at multiple times during the night. We demonstrate this new technique for the Moon using data from the Lunar Reconnaissance Orbiter (LRO) Diviner radiometer in conjunction with three dimensional thermal modeling, leveraging the differential cooling rates of different rock sizes. We assume an exponential rock size frequency distribution, which has been shown to yield a good fit to rock populations in various locations on the Moon, Mars, and Earth [2, 3] and solve for the best radiance fits as a function of local time and wavelength. This method presents several advantages: 1) unlike other thermally derived rock abundance techniques, it is sensitive to rocks smaller than the diurnal skin depth; 2) it does not result in apparent decrease in rock abundance at night; and 3) it can be validated using images taken at the lunar surface. This method yields both the fraction of the surface covered in rocks of all sizes and the exponential factor, which defines the rate of drop-off in the exponential function at large rock sizes. We will present maps of both these parameters for the Moon, and provide a geological interpretation. In particular, this method reveals rocks in the lunar highlands that are smaller than previous thermal methods could detect. [1] Bandfield J. L. et al. (2011) JGR, 116, E00H02. [2] Golombek and Rapp (1997) JGR, 102, E2, 4117-4129. [3] Cintala, M.J. and K.M. McBride (1995) NASA Technical Memorandum 104804.

  1. Fractal analysis of the fracture strength of lava dome material based on the grain size distribution of block-and-ash flow deposits at Unzen Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Suzuki-Kamata, Keiko; Kusano, Takashi; Yamasaki, Kazuhito

    2009-10-01

    A fractal theory of rock fragmentation is applied to block-and-ash flow deposits from the Fugendake dome, Unzen Volcano, Kyushu, Japan, in order to analyze the material strength and the energy required for size reduction of the source lava dome. Two fractal dimensions h and Ds, which are mutually interchangeable, represent the relative strength and energy for particles reduced to a given size. They can be theoretically estimated from the power relations of a reference grain size to the cumulative mass and number of fragments smaller than that size. The Unzen-Fugendake block-and-ash flow deposits have been further modified by size sorting and secondary fragmentation that occurred during flowage, so that the h value decreases (or Ds value increases) with increasing distance from the source. Coarse, reversely graded deposits are, however, found to retain the original size population relatively well. The Ds values estimated from deposits of this type are compatible with those previously reported from decompression-fragmentation experiments conducted on the same dome material. The employed fractal approach could thus give insights into the potential mode of dome collapse that generates block-and-ash flows.

  2. Selecting series size where the generalized Pareto distribution best fits

    NASA Astrophysics Data System (ADS)

    Ben-Zvi, Arie

    2016-10-01

    Rates of arrival and magnitudes of hydrologic variables are frequently described by the Poisson and the generalized Pareto (GP) distributions. Variations of their goodness-of-fit to nested series are studied here. The variable employed is depth of rainfall events at five stations of the Israel Meteorological Service. Series sizes range from about 50 (number of years on records) to about 1000 (total number of recorded events). The goodness-of-fit is assessed by the Anderson-Darling test. Three versions of this test are applied here. These are the regular two-sided test (of which the statistic is designated here by A2), the upper one-sided test (UA2) and the adaptation to the Poisson distribution (PA2). Very good fits, with rejection significance levels higher than 0.5 for A2 and higher than 0.25 for PA2, are found for many series of different sizes. Values of the shape parameter of the GP distribution and of the predicted rainfall depths widely vary with series size. Small coefficients of variation are found, at each station, for the 100-year rainfall depths, predicted through the series with very good fit of the GP distribution. Therefore, predictions through series of very good fit appear more consistent than through other selections of series size. Variations of UA2, with series size, are found narrower than those of A2. Therefore, it is advisable to predict through the series of low UA2. Very good fits of the Poisson distribution to arrival rates are found for series with low UA2. But, a reversed relation is not found here. Thus, the model of Poissonian arrival rates and GP distribution of magnitudes suits here series with low UA2. It is recommended to predict through the series, to which the lowest UA2 is obtained.

  3. Statistical properties of the normalized ice particle size distribution

    NASA Astrophysics Data System (ADS)

    Delanoë, Julien; Protat, Alain; Testud, Jacques; Bouniol, Dominique; Heymsfield, A. J.; Bansemer, A.; Brown, P. R. A.; Forbes, R. M.

    2005-05-01

    Testud et al. (2001) have recently developed a formalism, known as the "normalized particle size distribution (PSD)", which consists in scaling the diameter and concentration axes in such a way that the normalized PSDs are independent of water content and mean volume-weighted diameter. In this paper we investigate the statistical properties of the normalized PSD for the particular case of ice clouds, which are known to play a crucial role in the Earth's radiation balance. To do so, an extensive database of airborne in situ microphysical measurements has been constructed. A remarkable stability in shape of the normalized PSD is obtained. The impact of using a single analytical shape to represent all PSDs in the database is estimated through an error analysis on the instrumental (radar reflectivity and attenuation) and cloud (ice water content, effective radius, terminal fall velocity of ice crystals, visible extinction) properties. This resulted in a roughly unbiased estimate of the instrumental and cloud parameters, with small standard deviations ranging from 5 to 12%. This error is found to be roughly independent of the temperature range. This stability in shape and its single analytical approximation implies that two parameters are now sufficient to describe any normalized PSD in ice clouds: the intercept parameter N*0 and the mean volume-weighted diameter Dm. Statistical relationships (parameterizations) between N*0 and Dm have then been evaluated in order to reduce again the number of unknowns. It has been shown that a parameterization of N*0 and Dm by temperature could not be envisaged to retrieve the cloud parameters. Nevertheless, Dm-T and mean maximum dimension diameter -T parameterizations have been derived and compared to the parameterization of Kristjánsson et al. (2000) currently used to characterize particle size in climate models. The new parameterization generally produces larger particle sizes at any temperature than the Kristjánsson et al. (2000

  4. Pore-size distributions of N-isopropylacrylamide (NIPA) hydrogels

    SciTech Connect

    Walther, D.H.; Blanch, H.W.; Prausnitz, J.M. |

    1993-11-01

    Pore-size distributions have been measured for N-isopropylacrylamide (NIPA) hydrogels at 25 and 32{degrees}C with swelling capacities 11.3 and 6.0 g swollen gel per g dry gel. The mixed-solute-exclusion method (introduced by Kuga) was used to obtain the experimental solute-exclusion curve which represents the amount of imbibed liquid inside the gel inaccessible for a solute of radius r. The pore-size distributions were obtained by using Casassa`s Brownian-motion model and numerically solving the Fredholm integral equation. The pore-size distributions of temperature-sensitive NIPA hydrogels are strongly dependent on temperature which determines swelling capacity. With increasing swelling capacity (from 6.0 to 11.3), the pore-size distribution shifts to higher mode values (27.3 to 50.6 {angstrom}) and to higher variance (1.07{center_dot}10{sup 3} to 3.58{center_dot}10{sup 3} {angstrom}{sup 2}).

  5. Asymmetric competition causes multimodal size distributions in spatially structured populations.

    PubMed

    Velázquez, Jorge; Allen, Robert B; Coomes, David A; Eichhorn, Markus P

    2016-01-27

    Plant sizes within populations often exhibit multimodal distributions, even when all individuals are the same age and have experienced identical conditions. To establish the causes of this, we created an individual-based model simulating the growth of trees in a spatially explicit framework, which was parametrized using data from a long-term study of forest stands in New Zealand. First, we demonstrate that asymmetric resource competition is a necessary condition for the formation of multimodal size distributions within cohorts. By contrast, the legacy of small-scale clustering during recruitment is transient and quickly overwhelmed by density-dependent mortality. Complex multi-layered size distributions are generated when established individuals are restricted in the spatial domain within which they can capture resources. The number of modes reveals the effective number of direct competitors, while the separation and spread of modes are influenced by distances among established individuals. Asymmetric competition within local neighbourhoods can therefore generate a range of complex size distributions within even-aged cohorts. © 2016 The Author(s).

  6. Modeling of Microporosity Size Distribution in Aluminum Alloy A356

    NASA Astrophysics Data System (ADS)

    Yao, Lu; Cockcroft, Steve; Zhu, Jindong; Reilly, Carl

    2011-12-01

    Porosity is one of the most common defects to degrade the mechanical properties of aluminum alloys. Prediction of pore size, therefore, is critical to optimize the quality of castings. Moreover, to the design engineer, knowledge of the inherent pore population in a casting is essential to avoid potential fatigue failure of the component. In this work, the size distribution of the porosity was modeled based on the assumptions that the hydrogen pores are nucleated heterogeneously and that the nucleation site distribution is a Gaussian function of hydrogen supersaturation in the melt. The pore growth is simulated as a hydrogen-diffusion-controlled process, which is driven by the hydrogen concentration gradient at the pore liquid interface. Directionally solidified A356 (Al-7Si-0.3Mg) alloy castings were used to evaluate the predictive capability of the proposed model. The cast pore volume fraction and size distributions were measured using X-ray microtomography (XMT). Comparison of the experimental and simulation results showed that good agreement could be obtained in terms of both porosity fraction and size distribution. The model can effectively evaluate the effect of hydrogen content, heterogeneous pore nucleation population, cooling conditions, and degassing time on microporosity formation.

  7. Sample Size Tables, "t" Test, and a Prevalent Psychometric Distribution.

    ERIC Educational Resources Information Center

    Sawilowsky, Shlomo S.; Hillman, Stephen B.

    Psychology studies often have low statistical power. Sample size tables, as given by J. Cohen (1988), may be used to increase power, but they are based on Monte Carlo studies of relatively "tame" mathematical distributions, as compared to psychology data sets. In this study, Monte Carlo methods were used to investigate Type I and Type II…

  8. Size and moisture distribution characteristics of walnuts and their components

    USDA-ARS?s Scientific Manuscript database

    The objective of this study was to determine the size characteristics and moisture content (MC) distributions of individual walnuts and their components, including hulls, shells and kernels under different harvest conditions. Measurements were carried out for three walnut varieties, Tulare, Howard a...

  9. Asymmetric competition causes multimodal size distributions in spatially structured populations

    PubMed Central

    Velázquez, Jorge; Allen, Robert B.; Coomes, David A.; Eichhorn, Markus P.

    2016-01-01

    Plant sizes within populations often exhibit multimodal distributions, even when all individuals are the same age and have experienced identical conditions. To establish the causes of this, we created an individual-based model simulating the growth of trees in a spatially explicit framework, which was parametrized using data from a long-term study of forest stands in New Zealand. First, we demonstrate that asymmetric resource competition is a necessary condition for the formation of multimodal size distributions within cohorts. By contrast, the legacy of small-scale clustering during recruitment is transient and quickly overwhelmed by density-dependent mortality. Complex multi-layered size distributions are generated when established individuals are restricted in the spatial domain within which they can capture resources. The number of modes reveals the effective number of direct competitors, while the separation and spread of modes are influenced by distances among established individuals. Asymmetric competition within local neighbourhoods can therefore generate a range of complex size distributions within even-aged cohorts. PMID:26817778

  10. Stand size, stand distribution, and rotation lengths for forest wildlife

    Treesearch

    Steven E. Backs; Russel R. Titus

    1989-01-01

    The key to managing forest wildlife is providing diverse habitats. Stand size, stand distribution, and rotation length determine how diverse habitats will be. Since the tenure of private forest owners is generally shorter than prescribed rotations, rotation recommendations serve more as guides to the amount and intensity of cutting needed to maintain desired habitat....

  11. Factors influencing the effect size distribution of adaptive substitutions

    PubMed Central

    Oakley, Christopher G.; Gould, Billie A.; Schemske, Douglas W.

    2016-01-01

    The distribution of effect sizes of adaptive substitutions has been central to evolutionary biology since the modern synthesis. Early theory proposed that because large-effect mutations have negative pleiotropic consequences, only small-effect mutations contribute to adaptation. More recent theory suggested instead that large-effect mutations could be favoured when populations are far from their adaptive peak. Here we suggest that the distributions of effect sizes are expected to differ among study systems, reflecting the wide variation in evolutionary forces and ecological conditions experienced in nature. These include selection, mutation, genetic drift, gene flow, and other factors such as the degree of pleiotropy, the distance to the phenotypic optimum, whether the optimum is stable or moving, and whether new mutation or standing genetic variation provides the source of adaptive alleles. Our goal is to review how these factors might affect the distribution of effect sizes and to identify new research directions. Until more theory and empirical work is available, we feel that it is premature to make broad generalizations about the effect size distribution of adaptive substitutions important in nature. PMID:27053750

  12. The Detection and Measurement of the Activity Size Distributions

    NASA Astrophysics Data System (ADS)

    Ramamurthi, Mukund

    The infiltration of radon into the indoor environment may cause the exposure of the public to excessive amounts of radioactivity and has spurred renewed research interest over the past several years into the occurrence and properties of radon and its decay products in indoor air. The public health risks posed by the inhalation and subsequent lung deposition of the decay products of Rn-222 have particularly warranted the study of their diffusivity and attachment to molecular cluster aerosols in the ultrafine particle size range (0.5-5 nm) and to accumulation mode aerosols. In this research, a system for the detection and measurement of the activity size distributions and concentration levels of radon decay products in indoor environments has been developed. The system is microcomputer-controlled and involves a combination of multiple wire screen sampler -detector units operated in parallel. The detection of the radioactivity attached to the aerosol sampled in these units permits the determination of the radon daughter activity -weighted size distributions and concentration levels in indoor air on a semi-continuous basis. The development of the system involved the design of the detection and measurement system, its experimental characterization and testing in a radon-aerosol chamber, and numerical studies for the optimization of the design and operating parameters of the system. Several concepts of utility to aerosol size distribution measurement methods sampling the ultrafine cluster size range evolved from this study, and are discussed in various chapters of this dissertation. The optimized multiple wire screen (Graded Screen Array) system described in this dissertation is based on these concepts. The principal facet of the system is its ability to make unattended measurements of activity size distributions and concentration levels of radon decay products on a semi-continuous basis. Thus, the capability of monitoring changes in the activity concentrations and size

  13. Novel magnetic Fe onion-like fullerene micrometer-sized particles of narrow size distribution

    NASA Astrophysics Data System (ADS)

    Snovski, Ron; Grinblat, Judith; Margel, Shlomo

    2012-01-01

    Magnetic polydivinylbenzene (PDVB)/magnetite micrometer-sized particles of narrow size distribution were prepared by entrapping Fe(CO)5 within the pores of uniform porous PDVB particles, followed by the thermal decomposition of the encapsulated Fe(CO)5 at 300 °C in a sealed cell under inert atmosphere. Magnetic Fe onion-like fullerene micrometer-sized particles of narrow size distribution have been prepared by the thermal decomposition of the PDVB/magnetite magnetic microspheres at 1100 °C under inert atmosphere. The graphitic coating protects the elemental iron particles from oxidation and thereby preserves their very high magnetic moment for at least a year. Characterization of these unique magnetic carbon graphitic particles was also performed.

  14. Size and energy distributions of interplanetary magnetic flux ropes

    NASA Astrophysics Data System (ADS)

    Feng, H. Q.; Wu, D. J.; Chao, J. K.

    2007-02-01

    In observations from 1995 to 2001 from the Wind spacecraft, 144 interplanetary magnetic flux ropes were identified in the solar wind around 1 AU. Their durations vary from tens of minutes to tens of hours. These magnetic flux ropes include many small- and intermediate-sized structures and display a continuous distribution in size. Energies of these flux ropes are estimated and it is found that the distribution of their energies is a good power law spectrum with an index ~-0.87. The possible relationship between them and solar eruptions is discussed. It is suggested that like interplanetary magnetic clouds are interplanetary coronal mass ejections, the small- and intermediate-sized interplanetary magnetic flux ropes are the interplanetary manifestations of small coronal mass ejections produced in small solar eruptions. However, these small coronal mass ejections are too weak to appear clearly in the coronagraph observations as an ordinary coronal mass ejection.

  15. Turbulent Concentration of Chondrules: Size Distribution and Multifractal Scaling

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.; Hogan, Robert C.; Paque, Julie M.; Dobrovolskis, Anthony R.

    1999-01-01

    Size-selective concentration of particles in 3D turbulence may be related to collection of chondrules and other constituents into primitive bodies in a weakly turbulent protoplanetary nebula. In the terrestrial planet region, both the characteristic size and narrow size distribution of chondrules are explained, whereas "fluffier" particles would be concentrated in lower density, or more intensely turbulent, regions of the nebula. The spatial distribution of concentrated particle density obeys multifractal scaling, suggesting a dose tie to the turbulent cascade process. This scaling behavior allows predictions of the concentration probabilities to be made in the protoplanetary nebula, which are so large (> 10(exp 3) - 10(exp 4)) that further studies must be made of the role of mass loading.

  16. The Size Distribution of Stardust Injected into the ISM

    NASA Technical Reports Server (NTRS)

    Krueger, D.; Sedlmayr, E.

    1996-01-01

    A multi-component method for the description of the evolution of the grain size distribution in consideration of a size dependent grain drift and growth rate is applied in order to model dust driven winds around cool C-stars. Grain drift introduces several modifications concerning dust growth: on one hand the residence time in the region of efficient growth is reduced, on the other hand the growth efficiency is higher due to an increased collisional rate. For carbon grains the surface density of radical sites is increased, but on the other hand there is a reduction of the sticking efficiency of the growth species for drift velocities larger than a few km/s. It is found that the consideration of drift results in a considerable distortion of the size distribution as compared to the case of zero drift velocity. Generally, there are less, but larger grains if drift is included.

  17. Can the Size Distributions of Talus Particles be Predicted from Fracture Spacing Distributions on Adjacent Bedrock Cliffs?

    NASA Astrophysics Data System (ADS)

    Verdian, J. P.; Sklar, L. S.; Moore, J. R.; Rosenberg, D. J.

    2016-12-01

    What controls the size of sediments produced on hillslopes and supplied to river channels? This is an important but unanswered question in geomorphology and sedimentology. One hypothesis is that the initial size distribution of rock fragments eroded from bedrock is related to the distribution of spacing between pre-existing fractures in the bedrock. Slopes of talus that accumulate below eroding cliffs provide a simple natural experiment to test this hypothesis. We studied talus slopes and cliff faces at more than 20 locations in California, USA, where cliff retreat rates were previously measured by Moore et al., 2009. Rock types included andesite, basalt, granodiorite and meta-sediment. To quantify fracture spacing we measured fracture frequency and orientation along scan lines at the base of the cliff. We also used scaled photographs of the cliff face to characterize the shape, size and surface area of discrete blocks. We measured talus particle size distributions using surface point counts along transects oriented downslope from the cliff face, and mapped facies of distinct size distributions. To explore the effect of chemical weathering on talus size we sampled cliff faces and talus particles for x-ray fluorescence analysis to test for depletion of labile cations relative to source rock. Preliminary results suggest that talus size distributions are strongly correlated with bedrock fracture spacing, although systematic differences do occur. In some cases, talus sizes are larger than the spacing between fractures because the detached particles still retain truncated fractures. In other cases, talus is smaller than cliff fracture spacing, presumably because particle size is reduced by fragmentation on impact and weathering during transport down the talus slope. Further analysis will explore whether cliff retreat rate and extent of chemical weathering, as well as rock type and local climate, can explain between-site differences in the size of particles produced.

  18. Lognormal field size distributions as a consequence of economic truncation

    USGS Publications Warehouse

    Attanasi, E.D.; Drew, L.J.

    1985-01-01

    The assumption of lognormal (parent) field size distributions has for a long time been applied to resource appraisal and evaluation of exploration strategy by the petroleum industry. However, frequency distributions estimated with observed data and used to justify this hypotheses are conditional. Examination of various observed field size distributions across basins and over time shows that such distributions should be regarded as the end result of an economic filtering process. Commercial discoveries depend on oil and gas prices and field development costs. Some new fields are eliminated due to location, depths, or water depths. This filtering process is called economic truncation. Economic truncation may occur when predictions of a discovery process are passed through an economic appraisal model. We demonstrate that (1) economic resource appraisals, (2) forecasts of levels of petroleum industry activity, and (3) expected benefits of developing and implementing cost reducing technology are sensitive to assumptions made about the nature of that portion of (parent) field size distribution subject to economic truncation. ?? 1985 Plenum Publishing Corporation.

  19. Experimental comparison of measurement techniques for drop size distributions in liquid/liquid dispersions

    NASA Astrophysics Data System (ADS)

    Maaß, S.; Wollny, S.; Voigt, A.; Kraume, M.

    2011-02-01

    An online measurement technique for drop size distribution in stirred tank reactors is needed but has not yet been developed. Different approaches and different techniques have been published as the new standard during the last decade. Three of them (focus beam reflectance measurement, two-dimensional optical reflectance measurement techniques and a fiber optical FBR sensor) are tested, and their results are compared with trustful image analysis results from an in situ microscope. The measurement of drop sizes in liquid/liquid distribution is a major challenge for all tested measurement probes, and none provides exact results for the tested system of pure toluene/water compared to an endoscope. Not only the size analysis but also the change of the size over time gives unreasonable results. The influence of the power input on the drop size distribution was the only reasonable observation in this study. The FBR sensor was not applicable at all to the used system. While all three probes are based on laser back scattering, the general question of the usability of this principle for measuring evolving drop size distributions in liquid/liquid system is asked. The exterior smooth surface of droplets in such systems is leading to strong errors in the measurement of the size of the drops. That leads to widely divergent results. A different measurement principle should be used for online measurements of drop size distributions than laser back scattering.

  20. Prey size-distributions and size-specific foraging success of Ambystoma larvae.

    PubMed

    Smith, C K; Petranka, J W

    1987-01-01

    We examined how prey size-distributions influence size-specific foraing rate and food gain, i.e., food intake scaled to metabolic demands, in Jefferson's and small-mouth salamander larvae. Ambystoma jeffersonianum larvae sampled on 17 dates from a farm pond whose fauna was dominated by macrozooplankton and chironomid larvae were rarely gape-limited, and total volume of food in the stomach (VS) showed only a slight tendency to increase with larval size. Although 15 of 17 correlation coefficients of VS with larval size were positive, only 1 of 17 correlations were statistically significant, and body size explained only 8% of the overall variation in VS. Correlation coefficients of food gain and body size were positive in 9 cases and negative in 8, but only 3 were statistically significant.In contrast, Ambystoma texanum larvae in 42 samples taken from five sites dominated by macrozooplankton as well as relatively large isopods and amphipods were almost always gape-limited, and VS tended to increase markedly with larval size. 40 of 42 correlation coefficients of VS and larval size were positive, and 19 correlations were statistically significant. Body size in turn explained about 35% of the overall variation in VS. Correlation coefficients of food gain and larval size were positive in 32 of 42 samples, and 9 of 10 significant correlations were positive.When food is limiting and prey selection is not limited by gape, smaller larvae may grow as fast or in some cases faster than larger larvae because they are nearly as effective foragers, but have lower metabolic demands. Larger larvae may in turn grow faster than smaller larvae in environments which support a broad size spectrum of prey, particularly when gape limitations are highly disproportionate among size classes. The growth rate of larvae in one size class relative to another depends primarily on the extent to which increased foraging rate compensates for higher energy demands as body size increases. Size

  1. EXPLAINING THE GALACTIC INTERSTELLAR DUST GRAIN SIZE DISTRIBUTION FUNCTION

    SciTech Connect

    Casuso, E.; Beckman, J. E.

    2010-04-15

    We present here a new theoretical model designed to explain the interstellar dust grain size distribution function (IDGSDF), and compare its results with previous observationally derived distributions and with previous theoretical models. The range of grain sizes produced in the late stages of stars with different masses is considered, and folded into a model which takes into account the observed changes in the historical local star formation rate. Stars in different mass ranges reach their grain producing epochs at times whose mass dependence is quantifiable, and the range of grain sizes produced has also been estimated as a function of stellar mass. The results show an IDGSDF that has a global slope comparable to the observationally derived plot and three peaks at values of the grain radius comparable to those in the observationally derived distribution, which have their ultimate origin in three major peaks which have been observed in the star formation rate (SFR) over the past 15 Gyr. The model uses grain-grain interactions to modify pre-existing size distributions at lower grain sizes, where collisions appear more important. The interactions include disruption by collisions as well as coagulation to form larger grains. The initial distributions are given a range of initial functions (flat, Gaussian, fractal) for their physical parameters, as well as geometrical forms ranging from spherical to highly elongated. The particles are constrained in an imaginary box, and laws of inelastic collisions are applied. Finally, we combine the two models and produce an IDGSDF which is a notably good match to the observational fit, and specifically at small grain radii reproduces the data better than the 'SFR model' alone.

  2. Intensity and degree of segregation in bimodal and multimodal grain size distributions

    NASA Astrophysics Data System (ADS)

    Katra, Itzhak; Yizhaq, Hezi

    2017-08-01

    The commonly used grain size analysis technique which applies moments (sorting, skewness and kurtosis) is less useful in the case of sediments with bimodal size distributions. Herein we suggest a new simple method for analyzing the degree of grain size segregation in sand-sized sediment that has clear bimodal size distributions. Two main features are used to characterize the bimodal distribution: grain diameter segregation, which is the normalized difference between coarse and fine grain diameters, and the frequency segregation which is the normalized difference in frequencies between two modes. The new defined indices can be calculated from frequency plot curves and can be graphically represented on a two dimensional coordinate system showing the dynamical aspects of the size distribution. The results enable comparison between granular samples from different locations and/or times to shed new light on the dynamic processes involved in grain size segregation of sediments. We demonstrate here the use of this method to analyze bimodal distributions of aeolian granular samples mostly from aeolian megaripples. Six different aeolian cases were analyzed to highlight the method's applicability, which is relevant to wide research themes in the Earth and environmental sciences, and can furthermore be easily adapted to analyze polymodal grain size distributions.

  3. Optimizing the grain size distribution of allografts in bone impaction grafting.

    PubMed

    Putzer, David; Coraça-Huber, Debora; Wurm, Alexander; Schmoelz, Werner; Nogler, Michael

    2014-08-01

    In bone impaction grafting, allografts in the form of bone chips are used for reconstruction of defects and to induce bone remodeling. Optimizing grain size distribution of this allograft material should help prevent implant subsidence by achieving higher primary stability of the graft. We evaluated the influence of grain size distribution on the mechanical stability of allograft material. Bone tissue was rinsed, and the grain size distribution of the allograft material was determined by performing a sieve analysis. Uniaxial compression tests were carried out before and after a standardized compaction procedure for samples with controlled grain size distribution and a control group. Allografts with controlled grain size distribution showed a yield limit almost twice as high as in the control group after a standardized compaction procedure. A better interlocking between bone particles was observed compared to the control group. Thus, grain size distribution has a major impact on the mechanical stability of bone grafts. By controlling the grain size distribution of allograft material, a tighter packing can be achieved and subsequently implant subsidence of implants could be avoided. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  4. Particle-Size-Distribution of Nevada Test Site Soils

    SciTech Connect

    Spriggs, G; Ray-Maitra, A

    2007-09-17

    The amount of each size particle in a given soil is called the particle-size distribution (PSD), and the way it feels to the touch is called the soil texture. Sand, silt, and clay are the three particle sizes of mineral material found in soils. Sand is the largest sized particle and it feels gritty; silt is medium sized and it feels floury; and clay is the smallest and if feels sticky. Knowing the particle-size distribution of a soil sample helps to understand many soil properties such as how much water, heat, and nutrients the soil will hold, how fast water and heat will move through the soil, and what kind of structure, bulk density and consistence the soil will have. Furthermore, the native particle-size distribution of the soil in the vicinity of ground zero of a nuclear detonation plays a major role in nuclear fallout. For soils that have a high-sand content, the near-range fallout will be relatively high and the far-range fallout will be relatively light. Whereas, for soils that have a high-silt and high-clay content, the near-range fallout will be significantly lower and the far-range fallout will be significantly higher. As part of a program funded by the Defense Threat Reduction Agency (DTRA), the Lawrence Livermore National Laboratory (LLNL) has recently measured the PSDs from the various major areas at the Nevada Test Site where atmospheric detonations and/or nuclear weapon safety tests were performed back in the 50s and 60s. The purpose of this report is to document those results.

  5. Aged Boreal Biomass Burning Size Distributions from Bortas 2011

    NASA Astrophysics Data System (ADS)

    Pierce, J. R.; Sakamoto, K.; Allan, J. D.; Coe, H.; Taylor, J.; Duck, T.

    2014-12-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are strong functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate model inventories lead to uncertainties in the CCN concentrations and forcing estimates derived from these models. The BORTAS-B measurement campaign was designed to sample boreal biomass-burning outflow over Eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (aged ~ 1.5 - 2 days) from boreal wildfires in Northwestern Ontario. The composite median size-distribution yields a single dominant accumulation mode with Dpm = 232 nm, σ = 1.7, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA/ΔCO) along the path of Flight b622 show values of 0.08-0.18 μg m-3 ppbv-1 with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA production/evaporation within the aged plume over the sampling period. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution and flux corresponding to the BORTAS-B aged size-distributions. The model was restricted to coagulation and dilution processes only based on the insignificant net OA production/evaporation derived from the ΔOA/ΔCO enhancement ratios. Depending on the, we estimate that the fresh-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8. Thus, the size of the freshly emitted particles is somewhat unconstrained due to the uncertainties in the plume dilution rates.

  6. Size distribution of mist generated during metal machining.

    PubMed

    Thornburg, J; Leith, D

    2000-08-01

    Mist generated by machining processes is formed by three mechanisms: impaction, centrifugal force, and evaporation/condensation. This study characterized the size distribution of soluble and mineral oil mists that resulted from these formation mechanisms. Salient parameters influencing the particle size distributions also were identified. Variables investigated included metalworking fluid and machining characteristics. The size distribution of the mist generated on a small lathe by each mechanism was measured using an Aerosizer LD. For impaction, only the mineral oil viscosity influenced the mass median diameter of the mist. No parameter affected the geometric standard deviation. High-viscosity mineral oil mist had a mass median diameter of 6.1 microns and a geometric standard deviation of 2.0. Low-viscosity mineral oil mist had a mass median diameter of 21.9 microns and a geometric standard deviation of 2.2. The mass median diameter of the mist generated by centrifugal force depended on the type of metalworking fluid, fluid flow, and rotational speed of the lathe. Mass median diameters for low-viscosity mineral oil mist ranged from 5 to 110 microns. Mass median diameters for soluble oil mist varied between 40 and 80 microns. The average geometric standard deviation was 2.4, and was not affected by any parameter. The mass median diameter and geometric standard deviation of the mist generated by evaporation/condensation varied with the type of metalworking fluid. The mineral oil mist and soluble oil mist mass median diameters were 2.1 microns and 3.2 microns, respectively. No machining or fluid parameter was important because the mist size distribution depended on the rate of condensation, coagulation processes, and the dynamics of the apparatus. Using the size distribution data from all three mechanisms, the estimated inhalable, thoracic, and respirable fractions of the total mass generated for each metalworking fluid were 60 percent, 12 percent, and 8 percent

  7. Transneptunians as probes of planet building: The Plutino size distribution

    NASA Astrophysics Data System (ADS)

    Alexandersen, M.; Gladman, B.; Kavelaars, J.; Petit, J.; Gwyn, S.

    2014-07-01

    Planetesimals that formed during planet formation are the building blocks of giant planet cores; some are preserved as large transneptunian objects (TNOs). Previous work has shown steep power-law size distributions for TNOs of diameters > 100 km. Recent results claim a dramatic roll-over or divot in the size distribution of Neptunian Trojans (1:1 resonance with Neptune) and scattering TNOs, with a significant lack of intermediate-size D < 100 km planetesimals [1,2,3]. One theoretical explanation for this is that planetesimals were born big, skipping the intermediate sizes, contrary to the expectation of bottom-up planetesimal formation. Exploration of the TNO size distribution requires more precisely calibrated detections in order to improve statistics on these results. We have searched a 32 sq.deg. area near RA=2 hr to an r-band limiting magnitude of m_r=24.6 using the Canada-France-Hawaii Telescope. This coverage was near the Neptunian L4 region to maximise our detection rate, as this is where Neptunian Trojans reside and where Plutinos (and several other resonant populations) come to perihelion. This program successfully detected and tracked 77 TNOs and Centaurs for up to 17 months, giving us both the high-quality orbits and the quantitative detection efficiency needed for precise modelling. Among our detections were one Uranian Trojan, two Neptunian Trojans, 18 Plutinos (3:2 resonance with Neptune) and other resonant objects. We test TNO size and orbital-distribution models using a survey simulator, which simulates the detectability of model objects, accounting for the survey biases. We show that the Plutino size distribution cannot continue as a rising power law past H_r˜8.3 (equivalent to ˜100 km). A single power law is found rejectable at 99.5 % confidence, and a knee (a broken power law to a softer slope) is also rejectable. A divot (sudden drop in number of objects at a transition size), with parameters found independently for scattering TNOs by Shankman

  8. Size-frequency distributions of chondrules in CO3 chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1989-01-01

    The size-frequency distributions of chondrules were determined for eleven CO3 chondrites (including ALHA77003, ALHA77307, ALH82101, ALH85003, Colony, Felix, Isna, Kainsaz, Lance, Ornans, and Warrenton), using the results of petrographic analyses of thin sections. The mean proportion of different chondrule types in CO3 chondrites were estimated to be 69 percent POP, 18 percent PP, 8 percent PO, 2 percent BO, 2 percent RP, 1 percent C, and less than 0.1 percent GOP. These proportions are very different from those in ordinary or EH and CV chondrites, with the smaller proportion of nonporphyritic chondrules than EH chondrites, but a larger proportion than CV chondrites. Relative proportions of chondrule types vary with size interval; thus, with decreasing chondrule size, PO chondrules decrease fairly regularly in abundance, while RP chondrules are most abundant in the smallest size intervals.

  9. Determination of the pore size distribution and porosity of aerobic granules using size-exclusion chromatography.

    PubMed

    Zheng, Yu-Ming; Yu, Han-Qing

    2007-01-01

    The pore size distribution and porosity of aerobic granules with different diameters were evaluated using size-exclusion chromatography, in which polyethylene glycols and distilled water were, respectively, used as solute and mobile phase. The porosity of the aerobic granules varied from 68% to 93% and the exclusion limit, expressed as molecular mass, showed a significant difference. For the small-size granules with a diameter of 0.2-0.6mm, molecules greater than 137,000Da could not penetrate the pores, while the exclusion limits of the middle-size granules with a diameter of 0.6-0.9mm and large-size ones with a diameter of 0.9-1.5mm were 76,000 and 29,000Da, respectively. The extracellular polymeric substances of the granules might clog the pores and might be responsible for the reduced porosity. A correlation between the bioactivity and available porosity of the aerobic granules was found. The experimental results show that the size-exclusion chromatography was appropriate for elucidating the pore size distribution and porosity of the aerobic granules.

  10. Quasi-elastic light scattering determination of the size distribution of extruded vesicles.

    PubMed

    Kölchens, S; Ramaswami, V; Birgenheier, J; Nett, L; O'Brien, D F

    1993-04-01

    The size distribution of phospholipid vesicles prepared by the freeze thaw-extrusion method were determined by the non-perturbing technique of quasi-elastic light scattering (QELS) and compared to latex particles of known size. Multiangle QELS experiments were performed to avoid errors due to the angular dependence of the scattering function of the particles. The experimentally determined autocorrelation function was analyzed by multiple mathematical procedures, i.e. single exponential, CUMULANT, exponential sampling, non-negatively constrained least square and CONTIN, in order to select suitable models for vesicle characterization. The most consistent results were obtained with CUMULANT, non-negatively constrained least square and CONTIN. In many instances single exponential analysis gave comparable results to these procedures, which indicates the vesicles have a narrow distribution of sizes. The influence of filter pore size, extrusion pressure and lipid concentration on the size and size distribution of extruded vesicles was determined. Extrusion through 100-, 200- and 400-nm pore size filters produced a unimodal distribution of vesicles, with somewhat smaller diameters as the extrusion pressure increased. The larger the filter pore size, the more dependent the vesicle size was on applied pressure. The observed vesicle size was independent of the lipid concentration between 0.1 and 10 mg ml-1.

  11. New image processing software for analyzing object size-frequency distributions, geometry, orientation, and spatial distribution

    NASA Astrophysics Data System (ADS)

    Beggan, Ciarán; Hamilton, Christopher W.

    2010-04-01

    Geological Image Analysis Software (GIAS) combines basic tools for calculating object area, abundance, radius, perimeter, eccentricity, orientation, and centroid location, with the first automated method for characterizing the aerial distribution of objects using sample-size-dependent nearest neighbor (NN) statistics. The NN analyses include tests for (1) Poisson, (2) Normalized Poisson, (3) Scavenged k=1, and (4) Scavenged k=2 NN distributions. GIAS is implemented in MATLAB with a Graphical User Interface (GUI) that is available as pre-parsed pseudocode for use with MATLAB, or as a stand-alone application that runs on Windows and Unix systems. GIAS can process raster data (e.g., satellite imagery, photomicrographs, etc.) and tables of object coordinates to characterize the size, geometry, orientation, and spatial organization of a wide range of geological features. This information expedites quantitative measurements of 2D object properties, provides criteria for validating the use of stereology to transform 2D object sections into 3D models, and establishes a standardized NN methodology that can be used to compare the results of different geospatial studies and identify objects using non-morphological parameters.

  12. Aerosol size distribution, composition, and CO2 backscatter

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.; Porter, John N.

    1991-01-01

    The aerosol size distribution, composition, and CO2 backscatter at 10.6 microns (beta-CO2) were measured continuosly at the Mauna Loa Observatory (Hawaii) during January-March and November-December, 1988 periods to compare the characteristics of periods associated with appreciable Asian dust transport to that site (January-March) with those of periods characterized by low-dust condition. The aerosol size distribution in the range 0.15 micron to 7.6 microns was measured at temperatures of 40, 150, and 340 C to differentiate between volatile and nonvolatile aerosols. Large ranges of variability was found in measurements of aerosol size distribution during both periods, but the average distributions were similar for both the high-dust and the low-dust periods. However, values for beta-CO2 were more elevated (by about six times) during periods associated with active Asian dust transport to the observatory site than during the low-dust periods.

  13. Laboratory air bubble generation of various size distributions

    SciTech Connect

    Puleo, Jack A.; Johnson, Rex V.; Kooney, Tim N.

    2004-11-01

    Air bubble size in aqueous environments is an important factor governing natural processes ranging from fluid/atmosphere gas transfer to noise production. Bubbles are also known to affect various scientific instruments. In this study we investigate the production capability of eight inexpensive bubble generators using optical imaging techniques. Specific emphasis is directed towards determining bubble size and distribution for a given device, flow conditions, and type of water used (fresh vs salt). In almost all cases tested here, bubbles produced in salt water were more numerous, and smaller than for the same bubbler and conditions in fresh water. For porous media, the finer the pore size, the smaller the bubble produced with some variation depending on thickness of material containing the pore and water type. While no single generator tested was capable of spanning all the bubble sizes observed (100 to 6000 microns), the data contained herein will enable proper choice of bubbler or combinations thereof for future studies depending on the size and distribution of bubbles required.

  14. Effects of Grain Size Distributions on Fluid-Sediment Feedback

    NASA Astrophysics Data System (ADS)

    Conley, Daniel; Buscombe, Daniel

    2010-05-01

    Accounting for the feedback effects between sediment suspension and the generation of turbulence (Conley et al., 2008) has recently been shown to improve predictions of morphological evolution (Falchetti et al. 2010). Accounting for these interactions, which in general lead to an increase in the wave coherent component of transport relative to the mean component of transport, have been shown to even result in a change of transport direction. However most research to date has focused on simulations representing the unrealistic case of sediment beds composed of a single grain size. The recently initiated project TSSAR Waves (Turbulence, Sediment Stratification and Altered Resuspension under Waves) has initially focused on examining how the size distribution of bed sediments affects this fluid-sediment feedback. It has already been demonstrated (Conley et al. 2008) that the magnitude of the effects of sediment stratification scale with the ratio of maximum orbital velocity to grain settling velocity suggesting that the effects will be highly dependent on the grain size distribution. The nature of these effects has been investigated utilizing a modified version of the Generalized Ocean Turbulence Model (GOTM). Implementation of the ability to handle size distributions involved investigating questions such as how the mobility of individual scaseize fractions are related to total bed mobility, how excess shear stress is partitioned among size classes and grain size dependency of the Schmidt number. Observations from these investigations will be presented as well as predictions of sediment mobilization and suspension which are compared to appropriate laboratory experiments. Reference: Conley, D.C., Falchetti, S., Lohmann, I.P., Brocchini, M. (2008) The effects of flow stratification by non-cohesive sediment on transport in high-energy wave-driven flows. J. Fluid Mech., 610, 43-67. Falchetti, S., Conley, D.C., Brocchini, M. Elgar, S. (2010), Nearshore bar migration and

  15. Clone size distributions in networks of genetic similarity

    NASA Astrophysics Data System (ADS)

    Hernández-García, E.; Rozenfeld, A. F.; Eguíluz, V. M.; Arnaud-Haond, S.; Duarte, C. M.

    2006-12-01

    We build networks of genetic similarity in which the nodes are organisms sampled from biological populations. The procedure is illustrated by constructing networks from genetic data of a marine clonal plant. An important feature in the networks is the presence of clone subgraphs, i.e. sets of organisms with identical genotype forming clones. As a first step to understanding the dynamics that has shaped these networks, we point up a relationship between a particular degree distribution and the clone size distribution in the populations. We construct a dynamical model for the population dynamics, focussing on the dynamics of the clones, and solve it for the required distributions. Scale free and exponentially decaying forms are obtained depending on parameter values, the first type being obtained when clonal growth is the dominant process. Average distributions are dominated by the power law behavior presented by the fastest replicating populations.

  16. Measurement of Droplet Size Distribution in Insecticide and Herbicide Sprays.

    DTIC Science & Technology

    1983-04-01

    exceeding 100 :m, this result is not critical to the measurement requirements of the U.S. Army. o The spread in the processed signal is less for mineral oil...AD-A136 391 MEASUREMENT OF DROPLET SIZE DISTRIRUTION IN INSECTICIDE 1/1 AND HERRICIDE SPRAYS(UI KLD ASSOCIATES INC HUNTINGTON U D S MAHLER APR 83...NATIONAL BUREAU Of SIANDARDS 1963 A r TR- 126 AD______ MEASUREMENT Or DROPLET SIZE DISTRIBUTION IN INSECTICIDE AND HERBICIDE SPRAYS Phase.I Final

  17. Rock sampling. [method for controlling particle size distribution

    NASA Technical Reports Server (NTRS)

    Blum, P. (Inventor)

    1971-01-01

    A method for sampling rock and other brittle materials and for controlling resultant particle sizes is described. The method involves cutting grooves in the rock surface to provide a grouping of parallel ridges and subsequently machining the ridges to provide a powder specimen. The machining step may comprise milling, drilling, lathe cutting or the like; but a planing step is advantageous. Control of the particle size distribution is effected primarily by changing the height and width of these ridges. This control exceeds that obtainable by conventional grinding.

  18. Particle size and surface area distributions of pharmaceutical powders by microcomputerized mercury porosimetry.

    PubMed

    Carli, F; Motta, A

    1984-02-01

    The Mayer-Stowe theory was applied to derive the particle size distribution of powders of pharmaceutical interest using mercury porosimetry. Particle size data obtained by this approach are fairly comparable with data derived by other, more popular, techniques such as the electrical sensing zone or the air jet sieving methods provided that the experimental value of the mercury-powder contact angle and the state of aggregation of the powder are carefully studied. Furthermore, by applying the Rootare-Prenzlow method a surface area distribution can also be derived from the same porosimetry data used to obtain the particle size distribution. All experiments were carried out with a microcomputerized mercury porosimeter, which allows storage of data during the analysis and a subsequent fast elaboration at the end of the run, with fully printed data on pore size, pore volume, surface area, and particle size of the powder sample.

  19. Effect of Particle Size Distribution on Slurry Rheology: Nuclear Waste Simulant Slurries

    SciTech Connect

    Chun, Jaehun; Oh, Takkeun; Luna, Maria L.; Schweiger, Michael J.

    2011-07-05

    Controlling the rheological properties of slurries has been of great interest in various industries such as cosmetics, ceramic processing, and nuclear waste treatment. Many physicochemical parameters, such as particle size, pH, ionic strength, and mass/volume fraction of particles, can influence the rheological properties of slurry. Among such parameters, the particle size distribution of slurry would be especially important for nuclear waste treatment because most nuclear waste slurries show a broad particle size distribution. We studied the rheological properties of several different low activity waste nuclear simulant slurries having different particle size distributions under high salt and high pH conditions. Using rheological and particle size analysis, it was found that the percentage of colloid-sized particles in slurry appears to be a key factor for rheological characteristics and the efficiency of rheological modifiers. This behavior was shown to be coupled with an existing electrostatic interaction between particles under a low salt concentration. Our study suggests that one may need to implement the particle size distribution as a critical factor to understand and control rheological properties in nuclear waste treatment plants, such as the U.S. Department of Energy’s Hanford and Savannah River sites, because the particle size distributions significantly vary over different types of nuclear waste slurries.

  20. Ultrafine particle size distributions near freeways: Effects of differing wind directions on exposure.

    PubMed

    Kozawa, Kathleen H; Winer, Arthur M; Fruin, Scott A

    2012-12-01

    High ambient ultrafine particle (UFP) concentrations may play an important role in the adverse health effects associated with living near busy roadways. However, UFP size distributions change rapidly as vehicle emissions dilute and age. These size changes can influence UFP lung deposition rates and dose because deposition in the respiratory system is a strong function of particle size. Few studies to date have measured and characterized changes in near-road UFP size distributions in real-time, thus missing transient variations in size distribution due to short-term fluctuations in wind speed, direction, or particle dynamics. In this study we measured important wind direction effects on near-freeway UFP size distributions and gradients using a mobile platform with 5-s time resolution. Compared to more commonly measured perpendicular (downwind) conditions, parallel wind conditions appeared to promote formation of broader and larger size distributions of roughly one-half the particle concentration. Particles during more parallel wind conditions also changed less in size with downwind distance and the fraction of lung-deposited particle number was calculated to be 15% lower than for downwind conditions, giving a combined decrease of about 60%. In addition, a multivariate analysis of several variables found meteorology, particularly wind direction and temperature, to be important in predicting UFP concentrations within 150 m of a freeway (R(2) = 0.46, p = 0.014).

  1. Ultrafine particle size distributions near freeways: Effects of differing wind directions on exposure

    NASA Astrophysics Data System (ADS)

    Kozawa, Kathleen H.; Winer, Arthur M.; Fruin, Scott A.

    2012-12-01

    High ambient ultrafine particle (UFP) concentrations may play an important role in the adverse health effects associated with living near busy roadways. However, UFP size distributions change rapidly as vehicle emissions dilute and age. These size changes can influence UFP lung deposition rates and dose because deposition in the respiratory system is a strong function of particle size. Few studies to date have measured and characterized changes in near-road UFP size distributions in real-time, thus missing transient variations in size distribution due to short-term fluctuations in wind speed, direction, or particle dynamics. In this study we measured important wind direction effects on near-freeway UFP size distributions and gradients using a mobile platform with 5-s time resolution. Compared to more commonly measured perpendicular (downwind) conditions, parallel wind conditions appeared to promote formation of broader and larger size distributions of roughly one-half the particle concentration. Particles during more parallel wind conditions also changed less in size with downwind distance and the fraction of lung-deposited particle number was calculated to be 15% lower than for downwind conditions, giving a combined decrease of about 60%. In addition, a multivariate analysis of several variables found meteorology, particularly wind direction and temperature, to be important in predicting UFP concentrations within 150 m of a freeway (R2 = 0.46, p = 0.014).

  2. Pore size distribution in an uncompacted equilibrated ordinary chondrite

    SciTech Connect

    Friedrich, J.M.; Macke, R.J.; Wignarajah, D.P.; Rivers, M.L.; Britt, D.T.; Ebel, D.S.

    2008-05-30

    The extraordinarily uncompacted nature of the ordinary L chondrite fall Baszkowka gives a unique opportunity to investigate the potentially pre-compaction pore size distribution in an equilibrated ordinary chondrite. Using X-ray microtomography and helium pycnometry on two samples of Baszkowka, we have found that on average, two-thirds of the 19.0% porosity resides in inter- and intra-granular voids with volumes between {approx}3 x10{sup 05} and 3 mm{sup 3}. We show the cumulative number density of pore volumes observable by X-ray microtomography obeys a power law distribution function in this equilibrated ordinary chondrite. We foresee these data adding to our understanding of the impact processing of chondrites and their parent asteroids, where porosity and pore size play significant roles in the parameterization of impact events.

  3. Size distribution of cell pattern observed in gravitational instability.

    PubMed

    Shimokawa, Michiko; Kitahata, Hiroyuki; Sakurai, Tatsunari

    2013-01-01

    Gravitational instability occurs at the interface of two solutions when a higher-density solution (HDS) is placed on the surface of a lower-density solution (LDS). As the HDS sinks, a cell pattern forms on the surface. We investigate the size distribution of the cells in this pattern. We show that the cumulative size distribution obeys a power law with a power index that is independent of time as long as it is possible to neglect the interactions among the cells. To understand the power law mechanism, a simple model excluding the interactions is proposed, and we demonstrate that this simple model provides the power law measured in experiments. Our results indicate that independent cell generation and growth are key factors to understand the feature of the cell pattern.

  4. Group-size distribution of skeins of wild geese

    NASA Astrophysics Data System (ADS)

    Hayakawa, Yoshinori; Furuhashi, Sho

    2012-09-01

    In appropriate situations, large populations of geese exhibit dynamical rearrangements by repeated mergers and splits among the groups. We describe the grouping process in terms of a mean-field model based on the Smoluchowski equation of coagulation with fragmentation and observationally plausible kernels. To verify our model, we conducted field observations on skeins of airborne geese, noting both the group-size distribution and the group-forming processes. We found that the group-size distribution we obtained in our field measurements could be represented by a fractional power function with an exponential cutoff. This function matches the asymptotic form of the steady-state solution of our model. Furthermore, we estimated the effective number of individuals involved in interactions by comparison of the model to our field data.

  5. Computer Modeling of Crystallization and Crystal Size distributions

    NASA Astrophysics Data System (ADS)

    Amenta, R. V.

    2002-05-01

    The crystal size distribution of an igneous rock has been shown to be related to the crystallization kinetics. In order to better understand crystallization processes, the nucleation and growth of crystals in a closed system is modeled computationally and graphically. Units of volume analogous to unit cells are systematically attached to stationary crystal nuclei. The number of volume units attached to each crystal per growth stage is proportional to the crystal size insuring that crystal dimensional growth rates are constant regardless of their size. The number of new crystal nuclei per total system volume that form in each growth stage increases exponentially Cumulative crystal size distributions (CCSD) are determined for various stages of crystallization (30 percent, 60 pct, etc) from a database generated by the computer model, and each distribution is fit to an exponential function of the same form. Simulation results show that CCSD functions appear to fit the data reasonably well (R-square) with the greatest misfit at 100 pct crystallization. The crystal size distribution at each pct crystallization can be obtained from the derivative of the respective CCSD function. The log form of each crystal size distribution (CSD) is a linear function with negative slope. Results show that the slopes of the CSD functions at pcts crystallization up to 90 pct are parallel, but the slope at 100 pct crystallization differs from the others although still in approximate alignment. We suggest that real crystallization of igneous rocks may show this pattern. In the early stages of crystallization crystals are far apart and CSD's are ideal as predicted by theory based on growth of crystals in a brine. At advanced stages of crystallization growth collision boundaries develop between crystals. As contiguity increases crystals become blocked and inactive because they can no longer grow. As crystallization approaches 100 pct a significant number of inactive crystals exist resulting in

  6. The fossilized size distribution of the main asteroid belt

    NASA Astrophysics Data System (ADS)

    Bottke, William F.; Durda, Daniel D.; Nesvorný, David; Jedicke, Robert; Morbidelli, Alessandro; Vokrouhlický, David; Levison, Hal

    2005-05-01

    Planet formation models suggest the primordial main belt experienced a short but intense period of collisional evolution shortly after the formation of planetary embryos. This period is believed to have lasted until Jupiter reached its full size, when dynamical processes (e.g., sweeping resonances, excitation via planetary embryos) ejected most planetesimals from the main belt zone. The few planetesimals left behind continued to undergo comminution at a reduced rate until the present day. We investigated how this scenario affects the main belt size distribution over Solar System history using a collisional evolution model (CoEM) that accounts for these events. CoEM does not explicitly include results from dynamical models, but instead treats the unknown size of the primordial main belt and the nature/timing of its dynamical depletion using innovative but approximate methods. Model constraints were provided by the observed size frequency distribution of the asteroid belt, the observed population of asteroid families, the cratered surface of differentiated Asteroid (4) Vesta, and the relatively constant crater production rate of the Earth and Moon over the last 3 Gyr. Using CoEM, we solved for both the shape of the initial main belt size distribution after accretion and the asteroid disruption scaling law QD∗. In contrast to previous efforts, we find our derived QD∗ function is very similar to results produced by numerical hydrocode simulations of asteroid impacts. Our best fit results suggest the asteroid belt experienced as much comminution over its early history as it has since it reached its low-mass state approximately 3.9-4.5 Ga. These results suggest the main belt's wavy-shaped size-frequency distribution is a "fossil" from this violent early epoch. We find that most diameter D≳120 km asteroids are primordial, with their physical properties likely determined during the accretion epoch. Conversely, most smaller asteroids are byproducts of fragmentation

  7. Airblast atomization: studies on drop-size distribution

    SciTech Connect

    Rizk, N.K.; Lefebvze, A.H.

    1982-09-01

    The influence of air velocity and liquid properties on drop-size distribution is examined using an airblast atomizer in which a flat liquid sheet is exposed to high velocity air on both sides. Both photographic and lightscattering techniques are employed to measure drop sizes. The effect of the physical properties of liquids is studied by preparing special liquid solutions to obtain wide variations in one property while keeping the others sensibly constant. The results obtained show that increases in air velocity and/or reduction in liquid flow rate lead to more uniform sprays and a lower mean drop size. Higher values of viscosity and surface tension result in coarser sprays of larger mean drop size. The effect of liquid density on spray characteristics appears to be quite small. In general, it is found that any change in liquid properties or atomizer operating conditions which tends to lower the mean drop size will also tend to narrow the range of drop sizes produced.

  8. Size distributions of manure particles released under simulated rainfall.

    PubMed

    Pachepsky, Yakov A; Guber, Andrey K; Shelton, Daniel R; McCarty, Gregory W

    2009-03-01

    Manure and animal waste deposited on cropland and grazing lands serve as a source of microorganisms, some of which may be pathogenic. These microorganisms are released along with particles of dissolved manure during rainfall events. Relatively little if anything is known about the amounts and sizes of manure particles released during rainfall, that subsequently may serve as carriers, abode, and nutritional source for microorganisms. The objective of this work was to obtain and present the first experimental data on sizes of bovine manure particles released to runoff during simulated rainfall and leached through soil during subsequent infiltration. Experiments were conducted using 200 cm long boxes containing turfgrass soil sod; the boxes were designed so that rates of manure dissolution and subsequent infiltration and runoff could be monitored independently. Dairy manure was applied on the upper portion of boxes. Simulated rainfall (ca. 32.4 mm h(-1)) was applied for 90 min on boxes with stands of either live or dead grass. Electrical conductivity, turbidity, and particle size distributions obtained from laser diffractometry were determined in manure runoff and soil leachate samples. Turbidity of leachates and manure runoff samples decreased exponentially. Turbidity of manure runoff samples was on average 20% less than turbidity of soil leachate samples. Turbidity of leachate samples from boxes with dead grass was on average 30% less than from boxes with live grass. Particle size distributions in manure runoff and leachate suspensions remained remarkably stable after 15 min of runoff initiation, although the turbidity continued to decrease. Particles had the median diameter of 3.8 microm, and 90% of particles were between 0.6 and 17.8 microm. The particle size distributions were not affected by the grass status. Because manure particles are known to affect transport and retention of microbial pathogens in soil, more information needs to be collected about the

  9. Power law olivine crystal size distributions in lithospheric mantle xenoliths

    NASA Astrophysics Data System (ADS)

    Armienti, P.; Tarquini, S.

    2002-12-01

    Olivine crystal size distributions (CSDs) have been measured in three suites of spinel- and garnet-bearing harzburgites and lherzolites found as xenoliths in alkaline basalts from Canary Islands, Africa; Victoria Land, Antarctica; and Pali Aike, South America. The xenoliths derive from lithospheric mantle, from depths ranging from 80 to 20 km. Their textures vary from coarse to porphyroclastic and mosaic-porphyroclastic up to cataclastic. Data have been collected by processing digital images acquired optically from standard petrographic thin sections. The acquisition method is based on a high-resolution colour scanner that allows image capturing of a whole thin section. Image processing was performed using the VISILOG 5.2 package, resolving crystals larger than about 150 μm and applying stereological corrections based on the Schwartz-Saltykov algorithm. Taking account of truncation effects due to resolution limits and thin section size, all samples show scale invariance of crystal size distributions over almost three orders of magnitude (0.2-25 mm). Power law relations show fractal dimensions varying between 2.4 and 3.8, a range of values observed for distributions of fragment sizes in a variety of other geological contexts. A fragmentation model can reproduce the fractal dimensions around 2.6, which correspond to well-equilibrated granoblastic textures. Fractal dimensions >3 are typical of porphyroclastic and cataclastic samples. Slight bends in some linear arrays suggest selective tectonic crushing of crystals with size larger than 1 mm. The scale invariance shown by lithospheric mantle xenoliths in a variety of tectonic settings forms distant geographic regions, which indicate that this is a common characteristic of the upper mantle and should be taken into account in rheological models and evaluation of metasomatic models.

  10. The temperature and size distribution of large water clusters from a non-equilibrium model

    SciTech Connect

    Gimelshein, N.; Gimelshein, S.; Pradzynski, C. C.; Zeuch, T.; Buck, U.

    2015-06-28

    A hybrid Lagrangian-Eulerian approach is used to examine the properties of water clusters formed in neon-water vapor mixtures expanding through microscale conical nozzles. Experimental size distributions were reliably determined by the sodium doping technique in a molecular beam machine. The comparison of computed size distributions and experimental data shows satisfactory agreement, especially for (H{sub 2}O){sub n} clusters with n larger than 50. Thus validated simulations provide size selected cluster temperature profiles in and outside the nozzle. This information is used for an in-depth analysis of the crystallization and water cluster aggregation dynamics of recently reported supersonic jet expansion experiments.

  11. A POSSIBLE DIVOT IN THE SIZE DISTRIBUTION OF THE KUIPER BELT'S SCATTERING OBJECTS

    SciTech Connect

    Shankman, C.; Gladman, B. J.; Kaib, N.; Kavelaars, J. J.; Petit, J. M.

    2013-02-10

    Via joint analysis of a calibrated telescopic survey, which found scattering Kuiper Belt objects, and models of their expected orbital distribution, we explore the scattering-object (SO) size distribution. Although for D > 100 km the number of objects quickly rise as diameters decrease, we find a relative lack of smaller objects, ruling out a single power law at greater than 99% confidence. After studying traditional ''knees'' in the size distribution, we explore other formulations and find that, surprisingly, our analysis is consistent with a very sudden decrease (a divot) in the number distribution as diameters decrease below 100 km, which then rises again as a power law. Motivated by other dynamically hot populations and the Centaurs, we argue for a divot size distribution where the number of smaller objects rises again as expected via collisional equilibrium. Extrapolation yields enough kilometer-scale SOs to supply the nearby Jupiter-family comets. Our interpretation is that this divot feature is a preserved relic of the size distribution made by planetesimal formation, now ''frozen in'' to portions of the Kuiper Belt sharing a ''hot'' orbital inclination distribution, explaining several puzzles in Kuiper Belt science. Additionally, we show that to match today's SO inclination distribution, the supply source that was scattered outward must have already been vertically heated to the of order 10 Degree-Sign .

  12. Universal Asymptotic Clone Size Distribution for General Population Growth.

    PubMed

    Nicholson, Michael D; Antal, Tibor

    2016-11-01

    Deterministically growing (wild-type) populations which seed stochastically developing mutant clones have found an expanding number of applications from microbial populations to cancer. The special case of exponential wild-type population growth, usually termed the Luria-Delbrück or Lea-Coulson model, is often assumed but seldom realistic. In this article, we generalise this model to different types of wild-type population growth, with mutants evolving as a birth-death branching process. Our focus is on the size distribution of clones-that is the number of progeny of a founder mutant-which can be mapped to the total number of mutants. Exact expressions are derived for exponential, power-law and logistic population growth. Additionally, for a large class of population growth, we prove that the long-time limit of the clone size distribution has a general two-parameter form, whose tail decays as a power-law. Considering metastases in cancer as the mutant clones, upon analysing a data-set of their size distribution, we indeed find that a power-law tail is more likely than an exponential one.

  13. Taurocholate pool size and distribution in the fetal rat.

    PubMed Central

    Little, J M; Richey, J E; Van Thiel, D H; Lester, R

    1979-01-01

    Taurocholate concentrations in fetal and neonatal rats were determined by radioimmunoassay. Total body taurocholate pool size varied from 0.0049 +/- 0.0008 to 203 +/- 8 nmol/g body weight from day 5 of gestation to 5 d after birth. A 50-fold increase in taurocholate pool size was observed between days 15 and 19 of gestation. The distribution of taurocholate between liver, intestine, and the remainder of the carcass was determined for rats of gestational age 19 d to 5 d after birth. The major fraction of total body taurocholate was in the liver and intestine, with less than 15% in the remainder of the carcass. The ratio of taurocholate in intestine to taurocholate in liver, which was 1:17 at 19 d of gestation, had altered substantially to a ratio of 6:1 by 5 d after birth. Treatment of pregnant rats with 60 microgram/d of dexamethasone from gestational day 9 until sacrifice increased fetal taurocholate pool size by 80% at 15 d, 40% at 19 d, and 16% at 1 d after birth. Administration of dexamethasone to the mother also changed the ratio of taurocholate in intestine to taurocholate in liver. At 19 d of gestation, dexamethasone-treated mothers had fetuses with approximately equal amounts of taurocholate in intestine and liver. This suggested that adrenocorticosteroids stimulate the early maturation of factors controlling taurocholate pool size and tissue distribution in the rat fetus. PMID:447826

  14. Rheology of PVC Plastisol: Particle Size Distribution and Viscoelastic Properties.

    PubMed

    Nakajima, N.; Harrell, E. R.

    2001-06-01

    Plastisols of poly(vinyl chloride), PVC, are suspensions of fine particles in plasticizer with about 50% resin volume fraction. Typically, the gross particle size ranges from 15 to 0.2 &mgr;m and smaller, where the common practice of spray-drying these resins and subsequent grinding of larger particles dictate the size ranges including agglomerates as well as the primary particles. The plastisol is a pastelike liquid, which may be spread to coat substrates. The coated substrates are heated in an oven to gel and fuse the material for producing uniform, rubbery products. Because the first step of processing is spreading the plastisol on a substrate, rheology at room temperature is obviously important. The material is thixotropic under very low stress. The flow behavior is pseudoplastic and exhibits dilatancy and fracture at high shear rate. This work is concerned with the pseudoplastic behavior but the dynamic mechanical measurements are employed instead of the usual steady-state shear flow measurements. This is because the steady shear may break up agglomerates. The dynamic measurements with small strain-amplitude avoid the break-up of the agglomerates. This is important, because this work is concerned with the effects of the particle size distribution on the material behavior. The frequency dependence of both viscous and elastic behavior is recorded and presented with samples varying in particle size distribution. Copyright 2001 Academic Press.

  15. Use of elemental size distributions in identifying particle formation modes

    SciTech Connect

    Dunxi Yu; Minghou Xu; Hong Yao; Jiancai Sui; Xiaowei Liu; Yun Yu; Qian Cao

    2007-07-01

    The chemical composition of particles generated during pulverized coal combustion is the consequence of their formation processes. This work aims to use the size resolved elemental composition of coal-derived particles to identify their formation modes. A size-classified bituminous coal is burnt in a laboratory drop tube furnace at 1150, 1250, and 1350{sup o}C, respectively. The elemental composition of the size-segregated particles from coal combustion is analyzed and the total mass fraction size distributions of Si and Al are obtained. Three particle formation modes are observed in these distribution profiles. The coarse mode has the highest value of the total mass fraction of Si and Al while the ultrafine mode has the lowest one. The total mass fraction of Si and Al in these two modes is nearly independent of particle size. It is believed that the coarse mode is formed by the mineral coalescence mechanism and the ultrafine mode by the vaporization-condensation mechanism. The difference in the total mass fraction of Si and Al between the central mode and the other two indicates that the central mode is formed by different mechanisms. Based on the observation that the total mass fraction of Si and Al in this mode increases with increasing particle size, heterogeneous condensation of vaporized species on existing fine residual ash particles is proposed to account for the formation of these particles. The study of the elemental composition of the three modes represented in five categories verifies the proposed formation mechanisms for them to some extent. 30 refs., 5 figs., 2 tabs.

  16. Truncated shifted pareto distribution in assessing size distribution of oil and gas fields

    SciTech Connect

    Houghton, J.C.

    1988-11-01

    The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to the left-hand and right-hand side reduce the number of parameters to two. The TSP distribution has advantages over the more customary lognormal distribution because it has a simple analytic expression, allowing exact computation of several statistics of interest, has a J-shape, and has more flexibility in the thickness of the right-hand tail. Oil field sizes from the Minnelusa play in the Powder River Basin, Wyoming and Montana, are used as a case study. Probability plotting procedures allow easy visualization of the fit and help the assessment.

  17. Use of the truncated shifted Pareto distribution in assessing size distribution of oil and gas fields

    USGS Publications Warehouse

    Houghton, J.C.

    1988-01-01

    The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to the left-hand and right-hand side reduce the number of parameters to two. The TSP distribution has advantages over the more customary lognormal distribution because it has a simple analytic expression, allowing exact computation of several statistics of interest, has a "J-shape," and has more flexibility in the thickness of the right-hand tail. Oil field sizes from the Minnelusa play in the Powder River Basin, Wyoming and Montana, are used as a case study. Probability plotting procedures allow easy visualization of the fit and help the assessment. ?? 1988 International Association for Mathematical Geology.

  18. Characterizations of particle size distribution of the droplets exhaled by sneeze

    PubMed Central

    Han, Z. Y.; Weng, W. G.; Huang, Q. Y.

    2013-01-01

    This work focuses on the size distribution of sneeze droplets exhaled immediately at mouth. Twenty healthy subjects participated in the experiment and 44 sneezes were measured by using a laser particle size analyser. Two types of distributions are observed: unimodal and bimodal. For each sneeze, the droplets exhaled at different time in the sneeze duration have the same distribution characteristics with good time stability. The volume-based size distributions of sneeze droplets can be represented by a lognormal distribution function, and the relationship between the distribution parameters and the physiological characteristics of the subjects are studied by using linear regression analysis. The geometric mean of the droplet size of all the subjects is 360.1 µm for unimodal distribution and 74.4 µm for bimodal distribution with geometric standard deviations of 1.5 and 1.7, respectively. For the two peaks of the bimodal distribution, the geometric mean (the geometric standard deviation) is 386.2 µm (1.8) for peak 1 and 72.0 µm (1.5) for peak 2. The influences of the measurement method, the limitations of the instrument, the evaporation effects of the droplets, the differences of biological dynamic mechanism and characteristics between sneeze and other respiratory activities are also discussed. PMID:24026469

  19. Quality of the log-geometric distribution extrapolation for smaller undiscovered oil and gas pool size

    USGS Publications Warehouse

    Chenglin, L.; Charpentier, R.R.

    2010-01-01

    The U.S. Geological Survey procedure for the estimation of the general form of the parent distribution requires that the parameters of the log-geometric distribution be calculated and analyzed for the sensitivity of these parameters to different conditions. In this study, we derive the shape factor of a log-geometric distribution from the ratio of frequencies between adjacent bins. The shape factor has a log straight-line relationship with the ratio of frequencies. Additionally, the calculation equations of a ratio of the mean size to the lower size-class boundary are deduced. For a specific log-geometric distribution, we find that the ratio of the mean size to the lower size-class boundary is the same. We apply our analysis to simulations based on oil and gas pool distributions from four petroleum systems of Alberta, Canada and four generated distributions. Each petroleum system in Alberta has a different shape factor. Generally, the shape factors in the four petroleum systems stabilize with the increase of discovered pool numbers. For a log-geometric distribution, the shape factor becomes stable when discovered pool numbers exceed 50 and the shape factor is influenced by the exploration efficiency when the exploration efficiency is less than 1. The simulation results show that calculated shape factors increase with those of the parent distributions, and undiscovered oil and gas resources estimated through the log-geometric distribution extrapolation are smaller than the actual values. ?? 2010 International Association for Mathematical Geology.

  20. Characterizations of particle size distribution of the droplets exhaled by sneeze.

    PubMed

    Han, Z Y; Weng, W G; Huang, Q Y

    2013-11-06

    This work focuses on the size distribution of sneeze droplets exhaled immediately at mouth. Twenty healthy subjects participated in the experiment and 44 sneezes were measured by using a laser particle size analyser. Two types of distributions are observed: unimodal and bimodal. For each sneeze, the droplets exhaled at different time in the sneeze duration have the same distribution characteristics with good time stability. The volume-based size distributions of sneeze droplets can be represented by a lognormal distribution function, and the relationship between the distribution parameters and the physiological characteristics of the subjects are studied by using linear regression analysis. The geometric mean of the droplet size of all the subjects is 360.1 µm for unimodal distribution and 74.4 µm for bimodal distribution with geometric standard deviations of 1.5 and 1.7, respectively. For the two peaks of the bimodal distribution, the geometric mean (the geometric standard deviation) is 386.2 µm (1.8) for peak 1 and 72.0 µm (1.5) for peak 2. The influences of the measurement method, the limitations of the instrument, the evaporation effects of the droplets, the differences of biological dynamic mechanism and characteristics between sneeze and other respiratory activities are also discussed.

  1. Single-size thermometric measurements on a size distribution of neutral fullerenes.

    PubMed

    Cauchy, C; Bakker, J M; Huismans, Y; Rouzée, A; Redlich, B; van der Meer, A F G; Bordas, C; Vrakking, M J J; Lépine, F

    2013-05-10

    We present measurements of the velocity distribution of electrons emitted from mass-selected neutral fullerenes, performed at the intracavity free electron laser FELICE. We make use of mass-specific vibrational resonances in the infrared domain to selectively heat up one out of a distribution of several fullerene species. Efficient energy redistribution leads to decay via thermionic emission. Time-resolved electron kinetic energy distributions measured give information on the decay rate of the selected fullerene. This method is generally applicable to all neutral species that exhibit thermionic emission and provides a unique tool to study the stability of mass-selected neutral clusters and molecules that are only available as part of a size distribution.

  2. Simulation of 2D Fields of Raindrop Size Distributions

    NASA Astrophysics Data System (ADS)

    Berne, A.; Schleiss, M.; Uijlenhoet, R.

    2008-12-01

    The raindrop size distribution (DSD hereafter) is of primary importance for quantitative applications of weather radar measurements. The radar reflectivity~Z (directly measured by radar) is related to the power backscattered by the ensemble of hydrometeors within the radar sampling volume. However, the rain rate~R (the flux of water to the surface) is the variable of interest for many applications (hydrology, weather forecasting, air traffic for example). Usually, radar reflectivity is converted into rain rate using a power law such as Z=aRb. The coefficients a and b of the Z-R relationship depend on the DSD. The variability of the DSD in space and time has to be taken into account to improve radar rain rate estimates. Therefore, the ability to generate a large number of 2D fields of DSD which are statistically homogeneous provides a very useful simulation framework that nicely complements experimental approaches based on DSD data, in order to investigate radar beam propagation through rain as well as radar retrieval techniques. The proposed approach is based on geostatistics for structural analysis and stochastic simulation. First, the DSD is assumed to follow a gamma distribution. Hence a 2D field of DSDs can be adequately described as a 2D field of a multivariate random function consisting of the three DSD parameters. Such fields are simulated by combining a Gaussian anamorphosis and a multivariate Gaussian random field simulation algorithm. Using the (cross-)variogram models fitted on data guaranties that the spatial structure of the simulated fields is consistent with the observed one. To assess its validity, the proposed method is applied to data collected during intense Mediterranean rainfall. As only time series are available, Taylor's hypothesis is assumed to convert time series in 1D range profile. Moreover, DSD fields are assumed to be isotropic so that the 1D structure can be used to simulate 2D fields. A large number of 2D fields of DSD parameters are

  3. Finite-size effects on return interval distributions for weakest-link-scaling systems

    NASA Astrophysics Data System (ADS)

    Hristopulos, Dionissios T.; Petrakis, Manolis P.; Kaniadakis, Giorgio

    2014-05-01

    The Weibull distribution is a commonly used model for the strength of brittle materials and earthquake return intervals. Deviations from Weibull scaling, however, have been observed in earthquake return intervals and the fracture strength of quasibrittle materials. We investigate weakest-link scaling in finite-size systems and deviations of empirical return interval distributions from the Weibull distribution function. Our analysis employs the ansatz that the survival probability function of a system with complex interactions among its units can be expressed as the product of the survival probability functions for an ensemble of representative volume elements (RVEs). We show that if the system comprises a finite number of RVEs, it obeys the κ-Weibull distribution. The upper tail of the κ-Weibull distribution declines as a power law in contrast with Weibull scaling. The hazard rate function of the κ-Weibull distribution decreases linearly after a waiting time τc∝n1/m, where m is the Weibull modulus and n is the system size in terms of representative volume elements. We conduct statistical analysis of experimental data and simulations which show that the κ Weibull provides competitive fits to the return interval distributions of seismic data and of avalanches in a fiber bundle model. In conclusion, using theoretical and statistical analysis of real and simulated data, we demonstrate that the κ-Weibull distribution is a useful model for extreme-event return intervals in finite-size systems.

  4. Zooplankton size and distribution within mesoscale structures in the Mozambique Channel: A comparative approach using the TAPS acoustic profiler, a multiple net sampler and ZooScan image analysis

    NASA Astrophysics Data System (ADS)

    Lebourges-Dhaussy, A.; Huggett, J.; Ockhuis, S.; Roudaut, G.; Josse, E.; Verheye, H.

    2014-02-01

    Two surveys were conducted in the Mozambique Channel in November 2009 and April/May 2010 to study the influence of mesoscale eddies on the zooplanktonic component of the ecosystem. Three complementary methods were used to sample zooplankton: (1) hydro-acoustics with a TAPS™ multi-frequency zooplankton profiler; (2) in situ biological sampling using a Multinet with samples processed via the classical settled biovolume technique; (3) ZooScan image analysis which determines biovolume, size and taxonomic composition. This approach presented an ideal opportunity to compare the results of these different methods which highlighted a large overlap in their detectable size range. Each method favoured a particular size fraction of the population, i.e. TAPS for the microzooplankton (<0.1 mm ESR) and the Multinet and ZooScan for larger sizes (>3 mm ESR). In the case of the 2009 cruise, a well-established cyclone-anticyclone dipole was sampled, with results clearly indicating a higher concentration of zooplankton in the cyclonic eddy compared to the anticyclonic counterpart. The TAPS also detected high surface (0-22 m) concentrations of what appeared to be microzooplankton or marine snow in the cyclone. In 2010, the eddy field was less defined and more spatially variable compared to that in 2009. Two cyclonic and anticyclonic features were sampled during the cruise, each with different life histories and levels of stability. Results were inconsistent compared to those of 2009 and dependent on the size component of the population, with both cyclonic and anticyclonic features capable of having higher planktonic biomass. Differences in species composition between these mesoscale features were not too different and mainly a matter of relative biovolume. Less well formed eddy fields, particularly in the mid-Mozambique Channel, therefore appear to result in indistinct vertical and horizontal zooplankton distribution patterns.

  5. Modeling the dust size distribution in comets with dust fragmentation

    NASA Technical Reports Server (NTRS)

    Konno, Ichishiro; Huebner, Walter F.

    1990-01-01

    A hydrodynamic model was developed of a spherically symmetric dusty gas flow in a cometary atmosphere assuming a single fluid, inviscid, perfect gas. The hydrodynamics for gas and dust, which involves the gas drag force (momentum transfer), heat exchange between gas and dust, photodissociation energy for H2O gas, and radiative heating and cooling terms for dust particles, are solved using the Gear method for stiff, coupled differential equations. Calculations were done with a dust size distribution for radii alpha = 0.01 micron to 10 cm with densities variable with the size. A nucleus size of 4.0 km radius with a density of 0.5 g/cu cm and a total dust-to-gas mass ratio chi = 1 was adopted. There are indications from in situ observations that dust particle fragment into smaller ones. Fragmentation of dust particles was incorporated into the model. This is done by adding source and sink terms in the continuity equations for the dust. Lifetimes for the decay of dust particles were assumed as a function of particle size. It is also assumed that dust particles always fragment only into the next smaller size.

  6. INITIAL SIZE DISTRIBUTION OF THE GALACTIC GLOBULAR CLUSTER SYSTEM

    SciTech Connect

    Shin, Jihye; Kim, Sungsoo S.; Yoon, Suk-Jin; Kim, Juhan

    2013-01-10

    Despite the importance of their size evolution in understanding the dynamical evolution of globular clusters (GCs) of the Milky Way, studies that focus specifically on this issue are rare. Based on the advanced, realistic Fokker-Planck (FP) approach, we theoretically predict the initial size distribution (SD) of the Galactic GCs along with their initial mass function and radial distribution. Over one thousand FP calculations in a wide parameter space have pinpointed the best-fit initial conditions for the SD, mass function, and radial distribution. Our best-fit model shows that the initial SD of the Galactic GCs is of larger dispersion than today's SD, and that the typical projected half-light radius of the initial GCs is {approx}4.6 pc, which is 1.8 times larger than that of the present-day GCs ({approx}2.5 pc). Their large size signifies greater susceptibility to the Galactic tides: the total mass of destroyed GCs reaches 3-5 Multiplication-Sign 10{sup 8} M {sub Sun }, several times larger than previous estimates. Our result challenges a recent view that the Milky Way GCs were born compact on the sub-pc scale, and rather implies that (1) the initial GCs were generally larger than the typical size of the present-day GCs, (2) the initially large GCs mostly shrank and/or disrupted as a result of the galactic tides, and (3) the initially small GCs expanded by two-body relaxation, and later shrank by the galactic tides.

  7. Fog-Influenced Submicron Aerosol Number Size Distributions

    NASA Astrophysics Data System (ADS)

    Zikova, N.; Zdimal, V.

    2013-12-01

    The aim of this work is to evaluate the influence of fog on aerosol particle number size distributions (PNSD) in submicron range. Thus, five-year continuous time series of the SMPS (Scanning Mobility Particle Sizer) data giving information on PNSD in five minute time step were compared with detailed meteorological records from the professional meteorological station Kosetice in the Czech Republic. The comparison included total number concentration and PNSD in size ranges between 10 and 800 nm. The meteorological records consist from the exact times of starts and ends of individual meteorological phenomena (with one minute precision). The records longer than 90 minutes were considered, and corresponding SMPS spectra were evaluated. Evaluation of total number distributions showed considerably lower concentration during fog periods compared to the period when no meteorological phenomenon was recorded. It was even lower than average concentration during presence of hydrometeors (not only fog, but rain, drizzle, snow etc. as well). Typical PNSD computed from all the data recorded in the five years is in Figure 1. Not only median and 1st and 3rd quartiles are depicted, but also 5th and 95th percentiles are plotted, to see the variability of the concentrations in individual size bins. The most prevailing feature is the accumulation mode, which seems to be least influenced by the fog presence. On the contrary, the smallest aerosol particles (diameter under 40 nm) are effectively removed, as well as the largest particles (diameter over 500 nm). Acknowledgements: This work was supported by the projects GAUK 62213 and SVV-2013-267308. Figure 1. 5th, 25th, 50th, 75th and 95th percentile of aerosol particle number size distributions recorded during fog events.

  8. Measuring Technique of Bubble Size Distributions in Dough

    NASA Astrophysics Data System (ADS)

    Maeda, Tatsurou; Do, Gab-Soo; Sugiyama, Junichi; Oguchi, Kosei; Tsuta, Mizuki

    A novel technique to recognize bubbles in bread dough and analyze their size distribution was developed by using a Micro-Slicer Image Processing System (MSIPS). Samples were taken from the final stage of the mixing process of bread dough which generally consists of four distinctive stages. Also, to investigate the effect of freeze preservation on the size distribution of bubbles, comparisons were made between fresh dough and the dough that had been freeze preserved at .30°C for three months. Bubbles in the dough samples were identified in the images of MSIPS as defocusing spots due to the difference in focal distance created by vacant spaces. In case of the fresh dough, a total of 910 bubbles were recognized and their maximum diameter ranged from 0.4 to 70.5μm with an average of 11.1μm. On the other hand, a total of 1,195 bubbles were recognized from the freeze-preserved sample, and the maximum diameter ranged from 0.9 to 32.7μm with an average of 6.7μm. Small bubbles with maximum diameters less than 10μm comprised approximately 59% and 78% of total bubbles for fresh and freeze-preserved dough samples, respectively. The results indicated that the bubble size of frozen dough is smaller than that of unfrozen one. The proposed method can provide a novel tool to investigate the effects of mixing and preservation treatments on the size, morphology and distribution of bubbles in bread dough.

  9. Size distribution and dry deposition of road dust PAHs

    SciTech Connect

    Yang, H.H.; Chiang, C.F.; Lee, W.J.; Hwang, K.P.; Wu, E.M.Y.

    1999-07-01

    The size distribution of polycyclic aromatic hydrocarbons (PAHs) for road dust and for the engine exhaust of both gasoline-powered cars and motorcycles was investigated. In addition, by using the measured size distribution data, monitoring and modeling the PAH dry deposition, the contribution fraction of road dust on the dry deposition materials was also studied. Twenty-one PAHs were analyzed primarily by using a gas chromatograph/mass spectrometer (GC/MS). The mass median diameters (MMDs) of 21 individual PAHs for resuspendable road dust (cut size < 100 {micro}m) ranged between 63.4 {micro}m and 65.5 {micro}m. However, the MMDs of total-PAH size distributions for the engine exhaust of both gasoline-powered cars and four-stroke motorcycles averaged 0.45 {micro}m and 0.35 {micro}m, respectively, which were near the MMDs of PAHs (average 0.50 {micro}m) in the ambient air of traffic intersections. Suspended particle-phase total PAHs in the ambient air of traffic intersections were found to be more than 90% of the result of the automobile exhaust; that is, less than 10% of the amount was contributed by the road dust. However, the modeled MMDs of 21 individual PAHs on the dry deposition material were between 22.1 {micro}m and 44.6 {micro}m, and the contribution fraction of road dust on the PAH dry deposition was found to be more than 95%, even though the suspendable ambient-air PAHs were mainly from the mobile exhaust.

  10. Binary nucleation kinetics. I. Self-consistent size distribution

    SciTech Connect

    Wilemski, G.; Wyslouzil, B.E. ||

    1995-07-15

    Using the principle of detailed balance, we derive a new self-consistency requirement, termed the kinetic product rule, relating the evaporation coefficients and equilibrium cluster distribution for a binary system. We use this result to demonstrate and resolve an inconsistency for an idealized Kelvin model of nucleation in a simple binary mixture. We next examine several common forms for the equilibrium distribution of binary clusters based on the capillarity approximation and ideal vapor behavior. We point out fundamental deficiencies for each expression. We also show that each distribution yields evaporation coefficients that formally satisfy the new kinetic product rule but are physically unsatisfactory because they depend on the monomer vapor concentrations. We then propose a new form of the binary distribution function that is free of the deficiencies of the previous functions except for its reliance on the capillarity approximation. This new self-consistent classical (SCC) size distribution for binary clusters has the following properties: It satisfies the law of mass action; it reduces to an SCC unary distribution for clusters of a single component; and it produces physically acceptable evaporation rate coefficients that also satisfy the new kinetic product rule. Since it is possible to construct other examples of similarly well-behaved distributions, our result is not unique in this respect, but it does give reasonable predictions. As an illustration, we calculate binary nucleation rates and vapor activities for the ethanol--hexanol system at 260 K using the new SCC distribution and compare them to experimental results. The theoretical rates are uniformly higher than the experimental values over the entire vapor composition range. Although the predicted activities are lower, we find good agreement between the measured and theoretical slope of the critical vapor activity curve at a constant nucleation rate of 10{sup 7} cm{sup {minus}3} s{sup {minus}2}.

  11. Universal scaling of grain size distributions during dislocation creep

    NASA Astrophysics Data System (ADS)

    Aupart, Claire; Dunkel, Kristina G.; Angheluta, Luiza; Austrheim, Håkon; Ildefonse, Benoît; Malthe-Sørenssen, Anders; Jamtveit, Bjørn

    2017-04-01

    Grain size distributions are major sources of information about the mechanisms involved in ductile deformation processes and are often used as paleopiezometers (stress gauges). Several factors have been claimed to influence the stress vs grain size relation, including the water content (Jung & Karato 2001), the temperature (De Bresser et al., 2001), the crystal orientation (Linckens et al., 2016), the presence of second phase particles (Doherty et al. 1997; Cross et al., 2015), and heterogeneous stress distributions (Platt & Behr 2011). However, most of the studies of paleopiezometers have been done in the laboratory under conditions different from those in natural systems. It is therefore essential to complement these studies with observations of naturally deformed rocks. We have measured olivine grain sizes in ultramafic rocks from the Leka ophiolite in Norway and from Alpine Corsica using electron backscatter diffraction (EBSD) data, and calculated the corresponding probability density functions. We compared our results with samples from other studies and localities that have formed under a wide range of stress and strain rate conditions. All distributions collapse onto one universal curve in a log-log diagram where grain sizes are normalized by the mean grain size of each sample. The curve is composed of two straight segments with distinct slopes for grains above and below the mean grain size. These observations indicate that a surprisingly simple and universal power-law scaling describes the grain size distribution in ultramafic rocks during dislocation creep irrespective of stress levels and strain rates. Cross, Andrew J., Susan Ellis, and David J. Prior. 2015. « A Phenomenological Numerical Approach for Investigating Grain Size Evolution in Ductiley Deforming Rocks ». Journal of Structural Geology 76 (juillet): 22-34. doi:10.1016/j.jsg.2015.04.001. De Bresser, J. H. P., J. H. Ter Heege, and C. J. Spiers. 2001. « Grain Size Reduction by Dynamic

  12. Cloud droplet size distributions in low-level stratiform clouds

    SciTech Connect

    Miles, N.L.; Verlinde, J.; Clothiaux, E.E.

    2000-01-15

    A database of stratus cloud droplet size distribution parameters, derived from in situ data reported in the existing literature, was created, facilitating intercomparison among datasets and quantifying typical values and their variability. From the datasets, which were divided into marine and continental groups, several parameters are presented, including the total number concentration, effective diameter, mean diameter, standard deviation of the droplet diameters about the mean diameter, and liquid water content, as well as the parameters of modified gamma and lognormal distributions. In light of these results, the appropriateness of common assumptions used in remote sensing of cloud droplet size distributions is discussed. For example, vertical profiles of mean diameter, effective diameter, and liquid water content agreed qualitatively with expectations based on the current paradigm of cloud formation. Whereas parcel theory predicts that the standard deviation about the mean diameter should decrease with height, the results illustrated that the standard deviation generally increases with height. A feature common to all marine clouds was their approximately constant total number concentration profiles; however, the total number concentration profiles of continental clouds were highly variable. Without cloud condensation nuclei spectra, classification of clouds into marine and continental groups is based on indirect methods. After reclassification of four sets of measurements in the database, there was a fairly clear dichotomy between marine and continental clouds, but a great deal of variability within each classification. The relevant applications of this study lie in radiative transfer and climate issues, rather than in cloud formation and dynamics. Techniques that invert remotely sensed measurements into cloud droplet size distributions frequently rely on a priori assumptions, such as constant number concentration profiles and constant spectral width. The

  13. Predictive control of crystal size distribution in protein crystallization.

    PubMed

    Shi, Dan; Mhaskar, Prashant; El-Farra, Nael H; Christofides, Panagiotis D

    2005-07-01

    This work focuses on the modelling, simulation and control of a batch protein crystallization process that is used to produce the crystals of tetragonal hen egg-white (HEW) lysozyme. First, a model is presented that describes the formation of protein crystals via nucleation and growth. Existing experimental data are used to develop empirical models of the nucleation and growth mechanisms of the tetragonal HEW lysozyme crystal. The developed growth and nucleation rate expressions are used within a population balance model to simulate the batch crystallization process. Then, model reduction techniques are used to derive a reduced-order moments model for the purpose of controller design. Online measurements of the solute concentration and reactor temperature are assumed to be available, and a Luenberger-type observer is used to estimate the moments of the crystal size distribution based on the available measurements. A predictive controller, which uses the available state estimates, is designed to achieve the objective of maximizing the volume-averaged crystal size while respecting constraints on the manipulated input variables (which reflect physical limitations of control actuators) and on the process state variables (which reflect performance considerations). Simulation results demonstrate that the proposed predictive controller is able to increase the volume-averaged crystal size by 30% and 8.5% compared to constant temperature control (CTC) and constant supersaturation control (CSC) strategies, respectively, while reducing the number of fine crystals produced. Furthermore, a comparison of the crystal size distributions (CSDs) indicates that the product achieved by the proposed predictive control strategy has larger total volume and lower polydispersity compared to the CTC and CSC strategies. Finally, the robustness of the proposed method (achieved due to the presence of feedback) with respect to plant-model mismatch is demonstrated. The proposed method is

  14. The superbubble size distribution in the interstellar medium of galaxies.

    NASA Astrophysics Data System (ADS)

    Oey, M. S.; Clarke, C. J.

    1997-08-01

    We use the standard, adiabatic shell evolution to predict the differential size distribution N(R) for populations of OB superbubbles in a uniform ISM. Assuming that shell growth stalls upon pressure equilibrium with the ambient ISM, and that all shells have the same lifetime t_e, we derive N(R) for simple cases of superbubble creation rate and mechanical luminosity function (MLF). For constant creation and an MLF phi(L) ~ L^{-beta}, we find that N(R) ~ R^{1-2 beta} for R < R_e, and N(R) ~ R^{4-5 beta} for R > R_e, where the characteristic radius R_e ~ 1300 pc is the stall radius associated with t_e. For R < R_e, N(R) is dominated by stalled objects, while for R > R_e it is dominated by growing objects. The relation N(R) ~ R^{1-2\\beta} appears to be quite robust, and also results from the momentum-conserving shell evolution. We predict a peak in N(R) corresponding to individual SNRs, and suggest that the contribution of Type Ia SNRs should be apparent in the observed form of N(R). We present expressions for the porosity parameters, Q2D and Q3D, derived from our analysis. Q2D is dominated by the largest superbubbles for beta < 2 and individual SNRs for beta > 2, whereas Q3D is normally dominated by the few largest shells. We examine evolutionary effects on the HII region luminosity function (HII LF), in order to estimate beta. If the nebular luminosity {\\Lha} fades too quickly, the observed slope a of the HII LF will be steepened, since bright objects are quickly diminished. We find that for a nebular fading {\\Lha} ~ t^{-eta}, there is a minimum observed slope amin for the HII LFs, describing the relative importance of this effect. Empirical measurements all show a > amin, therefore implying that usually we may take \\beta = a. We also find that if nebular luminosity is instantaneously extinguished at some given age, rather than continuously fading, no amin will be observed. Comparison with the largely complete HI hole catalog for the SMC shows surprising

  15. Linking species abundance distributions and body size in monogenean communities.

    PubMed

    Poulin, Robert; Justine, Jean-Lou

    2008-06-01

    Parasite communities are characterised by one or a few numerically dominant species and many rare species. Although this pattern is well recognised, its underlying causes remain unknown. In this study, we tested whether variation in abundance among species within parasite communities can be explained by interspecific variation in body size. We used data on nine fish species (families Serranidae and Lethrinidae) from New Caledonia, each harbouring strictly host-specific diplectanid monogenean species with very uneven abundances. On each fish species, the most abundant monogenean species accounted for between one half and two thirds of all individuals recovered from the community, and its abundance was between 2 and 114 times greater than that of the second-most abundant species. However, there was no convincing evidence that the ratio of abundance values between the two most abundant species in a community co-varied with the ratio in their body sizes; thus, size differences cannot explain these differences in abundances between common species. It is surprising to note that in two of the three communities with enough species for an analysis to be performed, body size tended to correlate positively with abundance among all species of diplectanid monogeneans. Thus, although body size variation on its own cannot account for the pronounced differences in abundance among monogenean species within the same community, body size remains an important determinant of abundance as it relates to life-history traits underpinning reproductive rates and population growth in these unsaturated communities.

  16. The smallest crater production size-frequency distribution on Mars

    NASA Astrophysics Data System (ADS)

    Werner, Stephanie C.; Popova, Olga P.; Quantin, Cathy; Hartmann, William K.

    2015-04-01

    We selected areas on Mars that are mapped as very young, where we anticipate minimal surface modification since crater formation. By comparing shapes of the size-frequency distribution (SFD) of craters, measured with HiRISE and other image data in several such areas, we attempt to determine the least altered SFD, and thus identify the shape of the pristine, or "production" distribution (PSFD) at meter- and decameter-scale crater sizes on the surface of Mars. We identify several effects, dependent on factors such as surface materials, layered target materials, surface elevation, and the somewhat stochastic meteorite breakup mechanics, which may cause modest variations in the shape of the observed distributions at meter scales from one place to another on Mars, and suggest that surface modification on Mars, especially aeolian deposition modifies the crater record in very short time-scales. Better understanding of the PSFD shape not only allows more accurate crater chronometry of Mars, but also places limits on losses of weak bolides during passage through the atmosphere of Mars. We estimate the PSFD of Martian craters (including the effects of atmospheric loss of weak meteoroids, for craters down to diameter D ~ 2m) and will propose a new polynomial description for the smallest crater range currently covered by modern imagery.

  17. SIZE DISTRIBUTIONS OF SOLAR FLARES AND SOLAR ENERGETIC PARTICLE EVENTS

    SciTech Connect

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-09-10

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast ({>=}1000 km s{sup -1}) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes ({alpha} values) of power-law size distributions of the peak 1-8 A fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes {>=}1 pr cm{sup -2} s{sup -1} sr{sup -1}) and (b) fast CMEs were {approx}1.3-1.4 compared to {approx}1.2 for the peak proton fluxes of >10 MeV SEP events and {approx}2 for the peak 1-8 A fluxes of all SXR flares. The difference of {approx}0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  18. Size Distributions of Solar Flares and Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-01-01

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (much > 1000 km/s) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (alpha values) of power-law size distributions of the peak 1-8 Angs fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes much > 1 pr/sq cm/s/sr) and (b) fast CMEs were approx 1.3-1.4 compared to approx 1.2 for the peak proton fluxes of >10 MeV SEP events and approx 2 for the peak 1-8 Angs fluxes of all SXR flares. The difference of approx 0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  19. Marked point process models of raindrop-size distributions

    NASA Technical Reports Server (NTRS)

    Smith, James A.

    1993-01-01

    The principal process considered in this paper is the flux of raindrops through a volume of the atmosphere. This process is of fundamental importance for a wide variety of engineering and environmental problems, notably remote sensing of precipitation, infiltration of rainfall, soil erosion, atmospheric deposition of pollutants, and design of microwave communication systems. A marked point process model is developed in which the point process represents the arrival times of drops at the upper surface of a sample volume and the mark associated with a drop is its diameter. In the model, both the rate of occurrence of raindrops and the distribution of drop diameters vary randomly over time. Results that relate the drop-size distribution within the sample volume to the probability law of the drop-arrival process are presented. These results allow straightforward comparisons between temporal characterizations of drop-size distributions and spatial characterizations. Representations for derived processes such as rainfall rate and reflectivity are shown to be quite accurate using raindrop data from North Carolina.

  20. Marked point process models of raindrop-size distributions

    NASA Technical Reports Server (NTRS)

    Smith, James A.

    1993-01-01

    The principal process considered in this paper is the flux of raindrops through a volume of the atmosphere. This process is of fundamental importance for a wide variety of engineering and environmental problems, notably remote sensing of precipitation, infiltration of rainfall, soil erosion, atmospheric deposition of pollutants, and design of microwave communication systems. A marked point process model is developed in which the point process represents the arrival times of drops at the upper surface of a sample volume and the mark associated with a drop is its diameter. In the model, both the rate of occurrence of raindrops and the distribution of drop diameters vary randomly over time. Results that relate the drop-size distribution within the sample volume to the probability law of the drop-arrival process are presented. These results allow straightforward comparisons between temporal characterizations of drop-size distributions and spatial characterizations. Representations for derived processes such as rainfall rate and reflectivity are shown to be quite accurate using raindrop data from North Carolina.

  1. On computational approaches for size-and-shape distributions from sedimentation velocity analytical ultracentrifugation

    PubMed Central

    2009-01-01

    Sedimentation velocity analytical ultracentrifugation has become a very popular technique to study size distributions and interactions of macromolecules. Recently, a method termed two-dimensional spectrum analysis (2DSA) for the determination of size-and-shape distributions was described by Demeler and colleagues (Eur Biophys J 2009). It is based on novel ideas conceived for fitting the integral equations of the size-and-shape distribution to experimental data, illustrated with an example but provided without proof of the principle of the algorithm. In the present work, we examine the 2DSA algorithm by comparison with the mathematical reference frame and simple well-known numerical concepts for solving Fredholm integral equations, and test the key assumptions underlying the 2DSA method in an example application. While the 2DSA appears computationally excessively wasteful, key elements also appear to be in conflict with mathematical results. This raises doubts about the correctness of the results from 2DSA analysis. PMID:19806353

  2. Quantitative ultrasound estimates from populations of scatterers with continuous size distributions - Effects of the size estimator algorithm

    PubMed Central

    Oelze, Michael

    2012-01-01

    Quantitative ultrasonic techniques using backscatter coefficients (BSCs) may fail to produce physically meaningful estimates of effective scatterer diameter (ESD) when the analysis media contains scatterers of different sizes. In this work, three different estimator algorithms were used to produce estimates of ESD. The performance of the three estimators was compared over different frequency bands using simulations and experiments with physical phantoms. All estimators produced ESD estimates by comparing the estimated BSCs with a scattering model based on the backscattering cross-section of a single spherical fluid scatterer. The first estimator consisted of minimizing the average square deviation of the ratio between the estimated BSCs and the scattering model with both expressed in decibels. The second and third estimators consisted of minimizing the mean square error between the estimated BSCs and a linear transformation of the scattering model with and without considering an intercept, respectively. Simulations were conducted over several analysis bandwidths between 1 and 40 MHz from populations of scatterers with either a uniform size distribution or a distribution based on the inverse cubic of the size. Diameters of the distributions ranged between [25, 100], [25, 50], [50, 100], and [50, 75] μm. Experimental results were obtained from two gelatin phantoms containing Sephadex spheres ranging in diameter from 28 to 130 μm and 70 to 130 μm, respectively, and 5, 7.5, 10, and 13 MHz focused transducers. Significant differences in the performances of the ESD estimator algorithms as a function of the analysis frequency were observed. Specifically, the third estimator exhibited potential to produce physically meaningful ESD estimates even for large ka values when using a single-size scattering model if sufficient analysis bandwidth was available. PMID:23007782

  3. Quantitative ultrasound estimates from populations of scatterers with continuous size distributions: effects of the size estimator algorithm.

    PubMed

    Lavarello, Roberto; Oelze, Michael

    2012-09-01

    Quantitative ultrasonic techniques using backscatter coefficients (BSCs) may fail to produce physically meaningful estimates of effective scatterer diameter (ESD) when the analysis media contains scatterers of different sizes. In this work, three different estimator algorithms were used to produce estimates of ESD. The performance of the three estimators was compared over different frequency bands using simulations and experiments with physical phantoms. All estimators produced ESD estimates by comparing the estimated BSCs with a scattering model based on the backscattering cross section of a single spherical fluid scatterer. The first estimator consisted of minimizing the average square deviation of the logarithmically compressed ratio between the estimated BSCs and the scattering model. The second and third estimators consisted of minimizing the mean square error between the estimated BSCs and a linear transformation of the scattering model with and without considering an intercept, respectively. Simulations were conducted over several analysis bandwidths between 1 and 40 MHz from populations of scatterers with either a uniform size distribution or a distribution based on the inverse cubic of the size. Diameters of the distributions ranged between [25, 100], [25, 50], [50, 100], and [50, 75] μm. Experimental results were obtained from two gelatin phantoms containing cross-linked dextran gel spheres ranging in diameter from 28 to 130 μm and 70 to 130 μm, respectively, and 5-, 7.5-, 10-, and 13-MHz focused transducers. Significant differences in the performances of the ESD estimator algorithms as a function of the analysis frequency were observed. Specifically, the third estimator exhibited potential to produce physically meaningful ESD estimates even for large ka values when using a single-size scattering model if sufficient analysis bandwidth was available.

  4. Method for measuring the size distribution of airborne rhinovirus

    SciTech Connect

    Russell, M.L.; Goth-Goldstein, R.; Apte, M.G.; Fisk, W.J.

    2002-01-01

    About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor.

  5. Approximate sample sizes required to estimate length distributions

    USGS Publications Warehouse

    Miranda, L.E.

    2007-01-01

    The sample sizes required to estimate fish length were determined by bootstrapping from reference length distributions. Depending on population characteristics and species-specific maximum lengths, 1-cm length-frequency histograms required 375-1,200 fish to estimate within 10% with 80% confidence, 2.5-cm histograms required 150-425 fish, proportional stock density required 75-140 fish, and mean length required 75-160 fish. In general, smaller species, smaller populations, populations with higher mortality, and simpler length statistics required fewer samples. Indices that require low sample sizes may be suitable for monitoring population status, and when large changes in length are evident, additional sampling effort may be allocated to more precisely define length status with more informative estimators. ?? Copyright by the American Fisheries Society 2007.

  6. Dust generation in powders: Effect of particle size distribution

    NASA Astrophysics Data System (ADS)

    Chakravarty, Somik; Le Bihan, Olivier; Fischer, Marc; Morgeneyer, Martin

    2017-06-01

    This study explores the relationship between the bulk and grain-scale properties of powders and dust generation. A vortex shaker dustiness tester was used to evaluate 8 calcium carbonate test powders with median particle sizes ranging from 2μm to 136μm. Respirable aerosols released from the powder samples were characterised by their particle number and mass concentrations. All the powder samples were found to release respirable fractions of dust particles which end up decreasing with time. The variation of powder dustiness as a function of the particle size distribution was analysed for the powders, which were classified into three groups based on the fraction of particles within the respirable range. The trends we observe might be due to the interplay of several mechanisms like de-agglomeration and attrition and their relative importance.

  7. The scattering matrix for size distributions of irregular particles

    NASA Astrophysics Data System (ADS)

    Moreno, F.; Vilaplana, R.; Muñoz, O.; Molina, A.

    2005-05-01

    We have performed extensive calculations to obtain the scattering matrix elements for a size distribution of irregularly-shaped, randomly oriented particles by the Discrete Dipole Approximation (DDA) method, at size parameters X<25. We have studied the effects of changing the porosity of the particles and their refractive index on the scattering properties. To study both the color at blue and red incident wavelengths. The results will be used in the future for the interpretation of polarimetric observations of cosmic dust and laboratory measurements of scattering matrices of dust samples in a new light scattering facility which is currently built at the Instituto de Astrofísica de Andalucía in Granada, Spain.

  8. Evaluation of eruptive energy of a pyroclastic deposit applying fractal geometry to fragment size distributions

    NASA Astrophysics Data System (ADS)

    Paredes Marino, Joali; Morgavi, Daniele; Di Vito, Mauro; de Vita, Sandro; Sansivero, Fabio; Perugini, Diego

    2016-04-01

    Fractal fragmentation theory has been applied to characterize the particle size distribution of pyroclastic deposits generated by volcanic explosions. Recent works have demonstrated that fractal dimension on grain size distributions can be used as a proxy for estimating the energy associated with volcanic eruptions. In this work we seek to establish a preliminary analytical protocol that can be applied to better characterize volcanic fall deposits and derive the potential energy for fragmentation that was stored in the magma prior/during an explosive eruption. The methodology is based on two different techniques for determining the grain-size distribution of the pyroclastic samples: 1) dry manual sieving (particles larger than 297μm), and 2) automatic grain size analysis via a CamSizer-P4®device, the latter measure the distribution of projected area, obtaining a cumulative distribution based on volume fraction for particles up to 30mm. Size distribution data have been analyzed by applying the fractal fragmentation theory estimating the value of Df, i.e. the fractal dimension of fragmentation. In order to test our protocol we studied the Cretaio eruption, Ischia island, Italy. Results indicate that size distributions of pyroclastic fall deposits follow a fractal law, indicating that the fragmentation process of these deposits reflects a scale-invariant fragmentation mechanism. Matching the results from manual and automated techniques allows us to obtain a value of the "fragmentation energy" from the explosive eruptive events that generate the Cretaio deposits. We highlight the importance of these results, based on fractal statistics, as an additional volcanological tool for addressing volcanic risk based on the analyses of grain size distributions of natural pyroclastic deposits. Keywords: eruptive energy, fractal dimension of fragmentation, pyroclastic fallout.

  9. Saharan Dust Particle Size And Concentration Distribution In Central Ghana

    NASA Astrophysics Data System (ADS)

    Sunnu, A. K.

    2010-12-01

    A.K. Sunnu*, G. M. Afeti* and F. Resch+ *Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology (KNUST) Kumasi, Ghana. E-mail: albertsunnu@yahoo.com +Laboratoire Lepi, ISITV-Université du Sud Toulon-Var, 83162 La Valette cedex, France E-mail: resch@univ-tln.fr Keywords: Atmospheric aerosol; Saharan dust; Particle size distributions; Particle concentrations. Abstract The Saharan dust that is transported and deposited over many countries in the West African atmospheric environment (5°N), every year, during the months of November to March, known locally as the Harmattan season, have been studied over a 13-year period, between 1996 and 2009, using a location at Kumasi in central Ghana (6° 40'N, 1° 34'W) as the reference geographical point. The suspended Saharan dust particles were sampled by an optical particle counter, and the particle size distributions and concentrations were analysed. The counter gives the total dust loads as number of particles per unit volume of air. The optical particle counter used did not discriminate the smoke fractions (due to spontaneous bush fires during the dry season) from the Saharan dust. Within the particle size range measured (0.5 μm-25 μm.), the average inter-annual mean particle diameter, number and mass concentrations during the northern winter months of January and February were determined. The average daily number concentrations ranged from 15 particles/cm3 to 63 particles/cm3 with an average of 31 particles/cm3. The average daily mass concentrations ranged from 122 μg/m3 to 1344 μg/m3 with an average of 532 μg/m3. The measured particle concentrations outside the winter period were consistently less than 10 cm-3. The overall dust mean particle diameter, analyzed from the peak representative Harmattan periods over the 13-year period, ranged from 0.89 μm to 2.43 μm with an average of 1.5 μm ± 0.5. The particle size distributions exhibited the typical distribution pattern for

  10. The size frequency distribution of dormant Jupiter family comets

    NASA Astrophysics Data System (ADS)

    Whitman, Kathryn; Morbidelli, Alessandro; Jedicke, Robert

    2006-07-01

    We estimate the total number and the slope of the size-frequency distribution (SFD) of dormant Jupiter family comets (JFCs) by fitting a one-parameter model to the known population. We first select 61 near-Earth objects (NEOs) that are likely to be dormant JFCs because their orbits are dynamically coupled to Jupiter [Bottke, W.F., Morbidelli, A., Jedicke, R., Petit, J., Levison, H.F., Michel, P., Metcalfe, T.S., 2002a. Icarus 156, 399-433]. Then, from the numerical simulations of Levison and Duncan [1997. Icarus 127, 13-32], we construct an orbit distribution model for JFCs in the NEO orbital element space. We assume an orbit-independent SFD for all JFCs, the slope of which is our unique free parameter. Finally, we compute observational biases for dormant JFCs using a calibrated NEO survey simulator [Jedicke, R., Morbidelli, A., Spahr, T., Petit, J., Bottke, W.F., 2003. Icarus 161, 17-33]. By fitting the biased model to the data, we estimate that there are ˜75 dormant JFCs with H<18 in the NEO region and that the slope of their cumulative SFD is -1.5±0.3. Our slope for the SFD of dormant JFCs is very close to that of active JFCs as determined by Weissman and Lowry [2003. Lunar Planet. Sci. 34. Abstract 2003]. Thus, we argue that when JFCs fade they are likely to become dormant rather than to disrupt and that the fate of faded comets is size-independent. Our results imply that the size distribution of the JFC progenitors—the scattered disk trans-neptunian population—either (i) has a similar and shallow SFD or ( i) is slightly steeper and physical processes acting on the comets in a size-dependent manner creates the shallower active comet SFD. Our measured slope, typical of collisionally evolved populations with a size-dependent impact strength [Benz, W., Asphaug, E., 1999. Icarus 142, 5-20], suggests that scattered disk bodies reached collisional equilibrium inside the protoplanetary disk prior to their removal from the planetary region.

  11. Snow grain size and shape distributions in northern Canada

    NASA Astrophysics Data System (ADS)

    Langlois, A.; Royer, A.; Montpetit, B.; Roy, A.

    2016-12-01

    Pioneer snow work in the 1970s and 1980s proposed new approaches to retrieve snow depth and water equivalent from space using passive microwave brightness temperatures. Numerous research work have led to the realization that microwave approaches depend strongly on snow grain morphology (size and shape), which was poorly parameterized since recently, leading to strong biases in the retrieval calculations. Related uncertainties from space retrievals and the development of complex thermodynamic multilayer snow and emission models motivated several research works on the development of new approaches to quantify snow grain metrics given the lack of field measurements arising from the sampling constraints of such variable. This presentation focuses on the unknown size distribution of snow grain sizes. Our group developed a new approach to the `traditional' measurements of snow grain metrics where micro-photographs of snow grains are taken under angular directional LED lighting. The projected shadows are digitized so that a 3D reconstruction of the snow grains is possible. This device has been used in several field campaigns and over the years a very large dataset was collected and is presented in this paper. A total of 588 snow photographs from 107 snowpits collected during the European Space Agency (ESA) Cold Regions Hydrology high-resolution Observatory (CoReH2O) mission concept field campaign, in Churchill, Manitoba Canada (January - April 2010). Each of the 588 photographs was classified as: depth hoar, rounded, facets and precipitation particles. A total of 162,516 snow grains were digitized across the 588 photographs, averaging 263 grains/photo. Results include distribution histograms for 5 `size' metrics (projected area, perimeter, equivalent optical diameter, minimum axis and maximum axis), and 2 `shape' metrics (eccentricity, major/minor axis ratio). Different cumulative histograms are found between the grain types, and proposed fits are presented with the

  12. Mass size distributions of elemental aerosols in industrial area.

    PubMed

    Moustafa, Mona; Mohamed, Amer; Ahmed, Abdel-Rahman; Nazmy, Hyam

    2015-11-01

    Outdoor aerosol particles were characterized in industrial area of Samalut city (El-minia/Egypt) using low pressure Berner cascade impactor as an aerosol sampler. The impactor operates at 1.7 m(3)/h flow rate. Seven elements were investigated including Ca, Ba, Fe, K, Cu, Mn and Pb using atomic absorption technique. The mean mass concentrations of the elements ranged from 0.42 ng/m(3) (for Ba) to 89.62 ng/m(3) (for Fe). The mass size distributions of the investigated elements were bi-modal log normal distribution corresponding to the accumulation and coarse modes. The enrichment factors of elements indicate that Ca, Ba, Fe, K, Cu and Mn are mainly emitted into the atmosphere from soil sources while Pb is mostly due to anthropogenic sources.

  13. ELECTROSTATIC BARRIER AGAINST DUST GROWTH IN PROTOPLANETARY DISKS. I. CLASSIFYING THE EVOLUTION OF SIZE DISTRIBUTION

    SciTech Connect

    Okuzumi, Satoshi; Sakagami, Masa-aki; Tanaka, Hidekazu; Takeuchi, Taku

    2011-04-20

    Collisional growth of submicron-sized dust grains into macroscopic aggregates is the first step of planet formation in protoplanetary disks. These grains are expected to carry nonzero negative charges in the weakly ionized disks, but its effect on their collisional growth has not been fully understood so far. In this paper, we investigate how the charging affects the evolution of the dust size distribution properly taking into account the charging mechanism in a weakly ionized gas as well as porosity evolution through low-energy collisions. To clarify the role of the size distribution, we divide our analysis into two steps. First, we analyze the collisional growth of charged aggregates assuming a monodisperse (i.e., narrow) size distribution. We show that the monodisperse growth stalls due to the electrostatic repulsion when a certain condition is met, as was already expected in our previous work. Second, we numerically simulate dust coagulation using Smoluchowski's method to see how the outcome changes when the size distribution is allowed to freely evolve. We find that, under certain conditions, the dust undergoes bimodal growth where only a limited number of aggregates continue to grow, carrying a major part of the dust mass in the system. This occurs because remaining small aggregates efficiently sweep up free electrons to prevent the larger aggregates from being strongly charged. We obtain a set of simple criteria that allows us to predict how the size distribution evolves for a given condition. In Paper II, we apply these criteria to dust growth in protoplanetary disks.

  14. Estimation of riverbed grain-size distribution using image-processing techniques

    NASA Astrophysics Data System (ADS)

    Chang, Fi-John; Chung, Chang-Han

    2012-05-01

    SummaryQuantification of the grain size distribution of fluvial gravels remains an important and challenging issue in the study of river behavior. It is desirable for sampling techniques to achieve accurate estimation of grain size distribution, while simultaneously reducing the time spent. Recent advances in image analysis techniques have facilitated automated grain identification and measurement within digital images. In this study, an image-processing method fusing feedback pulse couple neural network and multilevel thresholding, the I-FM method, is proposed for automatic extraction of grain-size distribution based on digital photographs taken from a river-bed. A decisive image-merging algorithm is also developed for improving the quality of image segmentation in grain-size measurements. The experiments were conducted in both lab and field, and the proposed method was compared with traditional image processing methods. The proposed I-FM produces much more satisfactory results in estimating the amount of gravel and the percentiles of grain-size distribution in comparison with other image processing methods and manual sieving methods. It demonstrates the I-FM method is an efficient method for precisely measuring the grain-size distribution of river-bed material.

  15. Permeability of packed coal beds: The effect of particle size distribution, particle size and coal type

    SciTech Connect

    Greeff, S.C.; Slaghuis, J.H.; Walt, T.J. van der

    1998-12-31

    Sasol operates 97 Lurgi type gasifiers for the production of syngas using lump coal obtained from 7 captive coal mines. Permeability of packed coal beds of the coal has been identified as one of the major variables affecting stable operation which in turn affects maximum coal throughput and gas production. A tenth scale instrumented cold perspex model simulating a gasifier was constructed in which the pressure drop per unit bed length for a given gas flow could be measured. The effect of particle size distribution, particle size and coal type on the pressure drop (and hence permeability) was measured. The results were augmented by measuring void fractions as well as shape factors for the different coal types. The effect of size segregation during filling of the scale model was also investigated. Results have shown that bed permeability is strongly affected by the 3 variables investigated. The change in void fraction was found to be very small and could not be linked to the change in permeability. Size segregation resulted in a difference in gas flow rate between the center of the coal bed and against the wall of the model. The significance of the observations are discussed in terms of gasifier stability, optimum pressure drop and the effect of thermal size stability of coal upon entering the gasifier.

  16. Body size distributions signal a regime shift in a lake ecosystem

    USGS Publications Warehouse

    Spanbauer, Trisha; Allen, Craig R.; Angeler, David G.; Eason, Tarsha; Fritz, Sherilyn C.; Garmestani, Ahjond S.; Nash, Kirsty L.; Stone, Jeffery R.; Stow, Craig A.; Sundstrom, Shana M.

    2016-01-01

    Communities of organisms, from mammals to microorganisms, have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at multiple spatial and temporal scales. In this study, we assessed whether body size patterns serve as an indicator of a threshold between alternative regimes. Over the past 7000 years, the biological communities of Foy Lake (Montana, USA) have undergone a major regime shift owing to climate change. We used a palaeoecological record of diatom communities to estimate diatom sizes, and then analysed the discontinuous distribution of organism sizes over time. We used Bayesian classification and regression tree models to determine that all time intervals exhibited aggregations of sizes separated by gaps in the distribution and found a significant change in diatom body size distributions approximately 150 years before the identified ecosystem regime shift. We suggest that discontinuity analysis is a useful addition to the suite of tools for the detection of early warning signals of regime shifts.

  17. Body size distributions signal a regime shift in a lake ecosystem.

    PubMed

    Spanbauer, Trisha L; Allen, Craig R; Angeler, David G; Eason, Tarsha; Fritz, Sherilyn C; Garmestani, Ahjond S; Nash, Kirsty L; Stone, Jeffery R; Stow, Craig A; Sundstrom, Shana M

    2016-06-29

    Communities of organisms, from mammals to microorganisms, have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at multiple spatial and temporal scales. In this study, we assessed whether body size patterns serve as an indicator of a threshold between alternative regimes. Over the past 7000 years, the biological communities of Foy Lake (Montana, USA) have undergone a major regime shift owing to climate change. We used a palaeoecological record of diatom communities to estimate diatom sizes, and then analysed the discontinuous distribution of organism sizes over time. We used Bayesian classification and regression tree models to determine that all time intervals exhibited aggregations of sizes separated by gaps in the distribution and found a significant change in diatom body size distributions approximately 150 years before the identified ecosystem regime shift. We suggest that discontinuity analysis is a useful addition to the suite of tools for the detection of early warning signals of regime shifts.

  18. Backscattering enhancement from a random distribution of large discrete spherical scatterers with a size distribution

    SciTech Connect

    Mandt, C.E.; Leung Tsang )

    1992-12-01

    The authors study backscattering enhancement from a sparse random distribution of large scatterers wtih a size distribution. Second-order multiple-scattering theory based on the Bethe-Salpeter equation is used to compute the scattered field. The second-order cyclical term is used to account for the enhancement. The effects of polarization are included by using the Mie theory to account for scattering by individual particles, and the result is then averaged over the size distribution. Comparisons are made with experimental data for the case of a slab medium of sparsely distributed dielectric spheres with average ka of 298 and moderate optical thickness. Agreement between theory and experiment is good for both the copolarized and the cross-polarized returns. The Mueller matrix is also derived, an the degree of polarization is computed for the same case. Results show that including the cyclical term reduces the degree of polarization of the computed backscattered return. 19 refs., 5 figs., 2 tabs.

  19. Debiased Orbital and Size Distributions of the NEOs

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Morbidelli, A.; Jedicke, R.; Petit, J. M.; Levison, H. F.

    2001-11-01

    The orbital and absolute magnitude distribution of the Near-Earth Objects (NEOs) is difficult to compute, partly because known NEOs are biased by complicated observational selection effects but also because only a modest fraction of the entire NEO population has been discovered so far. To circumvent these problems, we created a model NEO population which was fit to known NEOs discovered or accidentally rediscovered by Spacewatch. Our method was to numerically integrate thousands of test bodies from four ``intermediate sources'': three in or adjacent to the main asteroid belt (Bottke et al. 2000, Science 288, 2190.) and one in the Kuiper belt (Levison and Duncan 1997, Icarus 127, 13). The test bodies which passed into the NEO region were tracked until they were eliminated. Next, we calculated the observational biases and assumed a functional form for the absolute magnitude (H) distribution associated with objects on those orbits. By merging the observational biases with our NEO dynamical ``roadmaps'' and an observed NEO H distribution, we produced a probability distribution which was fit to the biased NEO population. By testing a range of possible source combinations, a ``best-fit'' distribution was then deconvolved to provide the debiased orbital and H distributions for the NEO population as well as the relative importance of each NEO replenishment source. Our best-fit model predicts there are ~ 1010 H < 18 NEOs out to T > 2 (i.e., a < ~ 7.4 AU), with ~ 55% coming from the inner main belt (a < 2.5 AU), ~ 30% from the central main belt (2.5 < a < 2.8 AU), and ~ 15% from the Jupiter-family comet region. These results suggest that roughly 40% of the H < 18 NEOs have been found. The Amor, Apollo, and Aten populations contain 30%, 64%, and 6% of the H < 22 NEO population, respectively. The population of objects inside Earth's orbit (IEOs) are about 2% the size of the NEO population. Active and extinct comets make up a third of the entire km-sized NEO population with T

  20. Estimation of Weibull parameters from parameters of initial distribution of flaw size

    NASA Astrophysics Data System (ADS)

    Wakabayashi, C.; Yasuda, K.; Shiota, T.

    2009-11-01

    The distribution of the largest flaw size is derived from the initial distribution of flaw size based on extreme value statistics, and also the distribution of fracture origin size is given by transforming Weibull distribution by fracture mechanical relation. These two distributions are equivalent under uniaxial loading. By using this relation, their parameters are related each other and Weibull parameters are estimated from the parameters of the initial distribution of flaw size and the number of links.

  1. Light scattering by lunar-like particle size distributions

    NASA Technical Reports Server (NTRS)

    Goguen, Jay D.

    1991-01-01

    A fundamental input to models of light scattering from planetary regoliths is the mean phase function of the regolith particles. Using the known size distribution for typical lunar soils, the mean phase function and mean linear polarization for a regolith volume element of spherical particles of any composition were calculated from Mie theory. The two contour plots given here summarize the changes in the mean phase function and linear polarization with changes in the real part of the complex index of refraction, n - ik, for k equals 0.01, the visible wavelength 0.55 micrometers, and the particle size distribution of the typical mature lunar soil 72141. A second figure is a similar index-phase surface, except with k equals 0.1. The index-phase surfaces from this survey are a first order description of scattering by lunar-like regoliths of spherical particles of arbitrary composition. They form the basis of functions that span a large range of parameter-space.

  2. Influence of molecular size on tissue distribution of antibody fragments

    PubMed Central

    Li, Zhe; Krippendorff, Ben-Fillippo; Sharma, Sharad; Walz, Antje C.; Lavé, Thierry; Shah, Dhaval K.

    2016-01-01

    Biodistribution coefficients (BC) allow estimation of the tissue concentrations of proteins based on the plasma pharmacokinetics. We have previously established the BC values for monoclonal antibodies. Here, this concept is extended by development of a relationship between protein size and BC values. The relationship was built by deriving the BC values for various antibody fragments of known molecular weight from published biodistribution studies. We found that there exists a simple exponential relationship between molecular weight and BC values that allows the prediction of tissue distribution of proteins based on molecular weight alone. The relationship was validated by a priori predicting BC values of 4 antibody fragments that were not used in building the relationship. The relationship was also used to derive BC50 values for all the tissues, which is the molecular weight increase that would result in 50% reduction in tissue uptake of a protein. The BC50 values for most tissues were found to be ~35 kDa. An ability to estimate tissue distribution of antibody fragments based on the BC vs. molecular size relationship established here may allow better understanding of the biologics concentrations in tissues responsible for efficacy or toxicity. This relationship can also be applied for rational development of new biotherapeutic modalities with optimal biodistribution properties to target (or avoid) specific tissues. PMID:26496429

  3. Coarse atmospheric aerosol: size distributions of trace elements

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, K.; Colbeck, I.

    A sampler, employing nine single stage impactors placed in parallel within a portable wind tunnel, has been used to determine the metal content of coarse atmospheric aerosol. The wind tunnel maintains a constant flow environment for the collectors housed inside it, so that representative sampling conditions are achieved compared to the varied ambient wind conditions. At a flow rate of 8 m s -1 the 50% cut-off diameters of the impactors ranged from 7.8 to 38.8 μm. Measurements were conducted at a rural and urban site near Colchester in south east England. The samplers were analysed by PIXE for P, K, Ca, Fe, Ti, Mn, Cu, V, Co, Cr, Br, Zn, Ni, Sc and Pb. It is found that the sampler can be employed to quantitatively characterise the elemental mass size distribution for aerosol larger than 10 μm. The results indicate that a small fraction of the above earth and trace elements' metal mass is present in particles greater than 10 μm. This fraction for earth metals (Ca, K, Ti) is comparatively greater in the rural site than the urban site, while for trace metals (Mn, V, Cu, Cr) this fraction constitutes a more significant part of the coarse mass at the urban site. Trace element concentrations were of a similar order of magnitude to earlier literature reports. Although the number of measurements was limited it can be concluded that the size distributions obtained were characteristic of an unpolluted area.

  4. Measurement of size distributions of a coagulating aerosol. [Calcium carbonate

    SciTech Connect

    Loos, H.G.

    1984-05-01

    Measurements have been performed for the determination of the size distribution of a coagulating ultrafine aerosol over a time interval of up to about 30 min. The aerosol was contained in a balloon with an initial volume of 60 l subject to a temperature inversion for the purpose of quenching the free convection and thereby diminishing the aerosol loss to the balloon wall. The aerosol size distribution was measured with the TSI electrostatic aerosol classifier hooked up to a TSI aerosol electrometer. The initial aerosol had an average diameter of about 12 nm. Measurements were taken by computer at a rate of 1 measurement cycle every 3 s; 1 cycle consists of a measurement of time, and burst measurements of electrometer current, classifier rod voltage, 3 flow rates, and 5 temperatures, followed by the calculation of averages and standard deviations, and storage of the results in a data string. The TSI instruments have been modified to permit the automatic computer reading of the parameters mentioned above. A multiplexer has been built to allow the multiplet data to be measured by a single system voltmeter. Channel switching in the multiplexer can be done either automatically by using the ''delay'' signal emitted by the system voltmeter every time it makes a reading or by software control through the 16-bit parallel interface of the computer.

  5. Influence of molecular size on tissue distribution of antibody fragments.

    PubMed

    Li, Zhe; Krippendorff, Ben-Fillippo; Sharma, Sharad; Walz, Antje C; Lavé, Thierry; Shah, Dhaval K

    2016-01-01

    Biodistribution coefficients (BC) allow estimation of the tissue concentrations of proteins based on the plasma pharmacokinetics. We have previously established the BC values for monoclonal antibodies. Here, this concept is extended by development of a relationship between protein size and BC values. The relationship was built by deriving the BC values for various antibody fragments of known molecular weight from published biodistribution studies. We found that there exists a simple exponential relationship between molecular weight and BC values that allows the prediction of tissue distribution of proteins based on molecular weight alone. The relationship was validated by a priori predicting BC values of 4 antibody fragments that were not used in building the relationship. The relationship was also used to derive BC50 values for all the tissues, which is the molecular weight increase that would result in 50% reduction in tissue uptake of a protein. The BC50 values for most tissues were found to be ~35 kDa. An ability to estimate tissue distribution of antibody fragments based on the BC vs. molecular size relationship established here may allow better understanding of the biologics concentrations in tissues responsible for efficacy or toxicity. This relationship can also be applied for rational development of new biotherapeutic modalities with optimal biodistribution properties to target (or avoid) specific tissues.

  6. Microbubble Size Distributions Data Collection and Analysis

    DTIC Science & Technology

    2016-06-13

    Fog Nozzle, Inc., Greenfield, MA. Stored threshold criteria eliminated much of the potential errors associated with the manual subjective assignment...Greenfield, MA. Stored threshold criteria eliminated much of t~e potential errors associated with the manual subjective assignment of in-focus, single...and a computer image analyses system, with software designed to analyze bubbles. Stored threshold criteria eliminated 5 TM 841204 many of the

  7. The Analysis of Sodalime Granule Size Distributions

    DTIC Science & Technology

    2002-08-01

    340" Next idx Call ChiSquare Call BarGraph Label(37).Caption = Format$(minerror, "#.#####") Label(39).Caption...mesh30fit Graph1.LegendText = "measured" Graph1.LegendText = "best fit" Graph1.DrawMode = 2 End Sub F-6 Public Sub ChiSquare

  8. Size distribution and energy spectrum in the mixed state induced by Rayleigh-Taylor instability.

    PubMed

    Hazak, G; Elbaz, Y; Gardner, J H; Velikovich, A L; Schmitt, A J; Zalesak, S T

    2006-04-01

    A study--based on simulations and experiments as well as analytical derivations--of the internal structure of the fragmented ("mixed") state induced by the Rayleigh-Taylor instability at the interface between two fluids is presented. The distribution of sizes and the energy spectrum in the fragmented state are derived from the symmetries exhibited by the data and by dimensional analysis.

  9. The Angstrom Exponent and Bimodal Aerosol Size Distributions

    NASA Technical Reports Server (NTRS)

    Schuster, Gregory L.; Dubovik, Oleg; Holben, Brent H.

    2005-01-01

    Powerlaws have long been used to describe the spectral dependence of aerosol extinction, and the wavelength exponent of the aerosol extinction powerlaw is commonly referred to as the Angstrom exponent. The Angstrom exponent is often used as a qualitative indicator of aerosol particle size, with values greater than two indicating small particles associated with combustion byproducts, and values less than one indicating large particles like sea salt and dust. In this study, we investigate the relationship between the Angstrom exponent and the mode parameters of bimodal aerosol size distributions using Mie theory calculations and Aerosol Robotic Network (AERONET) retrievals. We find that Angstrom exponents based upon seven wavelengths (0.34, 0.38, 0.44, 0.5, 0.67, 0.87, and 1.02 micrometers) are sensitive to the volume fraction of aerosols with radii less then 0.6 micrometers, but not to the fine mode effective radius. The Angstrom exponent is also known to vary with wavelength, which is commonly referred to as curvature; we show how the spectral curvature can provide additional information about aerosol size distributions for intermediate values of the Angstrom exponent. Curvature also has a significant effect on the conclusions that can be drawn about two-wavelength Angstrom exponents; long wavelengths (0.67, 0.87 micrometers) are sensitive to fine mode volume fraction of aerosols but not fine mode effective radius, while short wavelengths (0.38, 0.44 micrometers) are sensitive to the fine mode effective radius but not the fine mode volume fraction.

  10. TNT particle size distributions from detonated 155-mm howitzer rounds.

    PubMed

    Taylor, Susan; Hewitt, Alan; Lever, James; Hayes, Charlotte; Perovich, Laura; Thorne, Phil; Daghlian, Chuck

    2004-04-01

    To achieve sustainable range management and avoid or minimize environmental contamination, the Army needs to know the amount of explosives deposited on ranges from different munitions and how these are degraded and transported under different geological and climatic conditions. The physical form of the deposited explosives has a bearing on this problem, yet the shapes and size distributions of the explosive particles remaining after detonations are not known. We collected residues from 8 high-order and 6 low-order non-tactical detonations of TNT-filled 155-mm rounds. We found significant variation in the amount of TNT scattered from the high-order detonations, ranging from 0.00001 to 2% of the TNT in the original shell. All low-order detonations scattered percent-level amounts of TNT. We imaged thousands of TNT particles and determined the size, mass and surface-area distributions of particles collected from one high-order and one low-order detonation. For the high-order detonation, particles smaller than 1 mm contribute most of the mass and surface area of the TNT scattered. For the low-order detonation, most of the scattered TNT mass was in the form of un-heated, centimeter-sized pieces whereas most of the surface area was again from particles smaller than 1 mm. We also observed that the large pieces of TNT disintegrate readily, giving rise to many smaller particles that can quickly dissolve. We suggest picking up the large pieces of TNT before they disintegrate to become point sources of contamination.

  11. Measurement of particle size distribution of soil and selected aggregate sizes using the hydrometer method and laser diffractometry

    NASA Astrophysics Data System (ADS)

    Guzmán, G.; Gómez, J. A.; Giráldez, J. V.

    2010-05-01

    Soil particle size distribution has been traditionally determined by the hydrometer or the sieve-pipette methods, both of them time consuming and requiring a relatively large soil sample. This might be a limitation in situations, such as for instance analysis of suspended sediment, when the sample is small. A possible alternative to these methods are the optical techniques such as laser diffractometry. However the literature indicates that the use of this technique as an alternative to traditional methods is still limited, because the difficulty in replicating the results obtained with the standard methods. In this study we present the percentages of soil grain size determined using laser diffractometry within ranges set between 0.04 - 2000 μm. A Beckman-Coulter ® LS-230 with a 750 nm laser beam and software version 3.2 in five soils, representative of southern Spain: Alameda, Benacazón, Conchuela, Lanjarón and Pedrera. In three of the studied soils (Alameda, Benacazón and Conchuela) the particle size distribution of each aggregate size class was also determined. Aggregate size classes were obtained by dry sieve analysis using a Retsch AS 200 basic ®. Two hundred grams of air dried soil were sieved during 150 s, at amplitude 2 mm, getting nine different sizes between 2000 μm and 10 μm. Analyses were performed by triplicate. The soil sample preparation was also adapted to our conditions. A small amount each soil sample (less than 1 g) was transferred to the fluid module full of running water and disaggregated by ultrasonication at energy level 4 and 80 ml of sodium hexametaphosphate solution during 580 seconds. Two replicates of each sample were performed. Each measurement was made for a 90 second reading at a pump speed of 62. After the laser diffractometry analysis, each soil and its aggregate classes were processed calibrating its own optical model fitting the optical parameters that mainly depends on the color and the shape of the analyzed particle. As a

  12. Ramifications of a Divot in the Kuiper Belt's Size Distribution

    NASA Astrophysics Data System (ADS)

    Gladman, Brett; Shankman, C.; Kaib, N.; Kavelaars, J.; Petit, J.

    2012-10-01

    Our recent detection (see Shankman et al., this meeting) of a divot in the distribution of numbers of Scattering TNOs as a function of absolute magnitude would, if extended to all Kuiper Belt sub-populations, simultaneously explain several outstanding curiosities in the literature. We examine these puzzles in the context of our proposed divot scenario and provide a cohesive picture of the "hot" Trans-Neptunian populations (the scattering, inner belt, hot main belt, outer/detached, and resonant populations). We explore the observed rollover in the Kuiper Belt's luminosity function, the "missing" Neptune Trojans, the source of the Jupiter Family Comets, and patterns seen in the hot/cold ratio as a function of magnitude. Our interpretation is that a detected divot is a preserved relic of the size distribution made by planetesimal formation, now "frozen in" to portions of the Kuiper Belt which share a "hot" orbital inclination distribution. This research was supported by the Canadian National Sciences and Engineering Research Council.

  13. The Use of Statistical End-Member Mixing Analysis (EMMA) of Grain Size Distributions to Characterize Site Deposition of a Deeply Stratified Paleoindian Rock Shelter, Harney Basin, Eastern Oregon

    NASA Astrophysics Data System (ADS)

    Collins, J. D., Jr.

    2014-12-01

    Sedimentological investigations were conducted on Excavation Unit 2 of Rimrock Draw Rockshelter (35HA3855), a deeply stratified, multi-component Paleoindian site located along the western margin of the Harney Basin, eastern Oregon. Field descriptions and end-member mixing analysis (EMMA) of grain-size distributions (GSD) of 13 sediment samples identified six stages of site formation: three stratigraphic units (SU), two unconformities, and a relict Bt soil horizon. EMMA resulted in the characterization of three end-members (EM) that correlate with field descriptions. EM's 1 and 2 represent 88.4% of the total variance among samples and are present within the upper-most stratigraphic unit, SU1, and the lower-most stratigraphic unit, SU3. EM 3 correlates with the poorly developed Bt horizon within the middle stratigraphic unit, SU2. EM 1 is a well-sorted coarse to medium sand interpreted as fluvial deposition. EM 2 is a trimodal deposit of poorly sorted sand, silt, and clay, interpreted as a predominantly aeolian deposition occasionally punctuated by colluvium derived from the colluvial wedge to the east of the Unit and from the brow of the rockshelter. EM 3 is a bimodal distribution of medium sand to fine silts and clays that represent a predominately aeolian deposit overprinted by a Bt horizon. The results of this study demonstrate the applicability of EMMA to distinguish between depositional units within an archaeological context and provide geologically meaningful interpretations of paleoenvironments for the development of hypotheses related to human environmental interactions.

  14. Grain-size distribution of volcaniclastic rocks 2: Characterizing grain size and hydraulic sorting

    NASA Astrophysics Data System (ADS)

    Jutzeler, Martin; McPhie, Jocelyn; Allen, Sharon R.; Proussevitch, A. A.

    2015-08-01

    Quantification of the grain size distribution of sediments allows interpretation of processes of transport and deposition. Jutzeler et al. (2012) developed a technique to determine grain size distribution of consolidated clastic rocks using functional stereology, allowing direct comparison between unconsolidated sediments and rocks. Here, we develop this technique to characterize hydraulic sorting and infer transport and deposition processes. We compare computed grain size and sorting of volcaniclastic rocks with field-based characteristics of volcaniclastic facies for which transport and depositional mechanisms have been inferred. We studied pumice-rich, subaqueous facies of volcaniclastic rocks from the Oligocene Ohanapecosh Formation (Ancestral Cascades, Washington, USA), Pliocene Dogashima Formation (Izu Peninsula, Honshu, Japan), Miocene Manukau Subgroup (Northland, New Zealand) and the Quaternary Sierra La Primavera caldera (Jalisco State, Mexico). These sequences differ in bed thickness, grading and abundance of matrix. We propose to evaluate grain size and sorting of volcaniclastic deposits by values of their modes, matrix proportion (< 2 mm; F-1) and D16, instead of median diameter (D50) and standard deviation parameters. F-1 and D16 can be uniformly used to characterize and compare sieving and functional stereology data. Volcaniclastic deposits typically consist of mixtures of particles that vary greatly in density and porosity. Hydraulic sorting ratios can be used to test whether mixed clast populations of pumice and dense clasts are hydraulically sorted with each other, considering various types of transport underwater. Evaluation of this ratio for our samples shows that most studied volcaniclastic facies are deposited by settling from density currents, and that basal dense clast breccias are emplaced by shear rolling. These hydraulic sorting ratios can be applied to any type of clastic rocks, and indifferently on consolidated and unconsolidated samples.

  15. Determining particle size distributions in the inhalable size range for wood dust collected by air samplers.

    PubMed

    Harper, Martin; Muller, Brian S; Bartolucci, Al

    2002-10-01

    In the absence of methods for determining particle size distributions in the inhalable size range with good discrimination, the samples collected by personal air sampling devices can only be characterized by their total mass. This parameter gives no information regarding the size distribution of the aerosol or the size-selection characteristics of different samplers in field use conditions. A method is described where the particles collected by a sampler are removed, suspended, and re-deposited on a mixed cellulose-ester filter, and examined by optical microscopy to determine particle aerodynamic diameters. This method is particularly appropriate to wood dust particles which are generally large and close to rectangular prisms in shape. Over 200 wood dust samples have been collected in three different wood-products industries, using the traditional closed-face polystyrene/acrylonitrile cassette, the Institute of Occupational Medicine inhalable sampler, and the Button sampler developed by the University of Cincinnati. A portion of these samples has been analyzed to determine the limitations of this method. Extensive quality control measures are being developed to improve the robustness of the procedure, and preliminary results suggest the method has an accuracy similar to that required of National Institute for Occupational Safety and Health (NIOSH) methods. The results should provide valuable insights into the collection characteristics of the samplers and the impact of these characteristics on comparison of sampler results to present and potential future limit values. The NIOSH Deep South Education and Research Center has a focus on research into hazards of the forestry and associated wood-products industry, and it is hoped to expand this activity in the future.

  16. Scale effects on the variability of the raindrop size distribution

    NASA Astrophysics Data System (ADS)

    Raupach, Timothy; Berne, Alexis

    2016-04-01

    The raindrop size distribution (DSD) is of utmost important to the study of rainfall processes and microphysics. All important rainfall variables can be calculated as weighted moments of the DSD. Qualitative precipitation estimation (QPE) algorithms and numerical weather prediction (NWP) models both use the DSD in order to calculate quantities such as the rain rate. Often these quantities are calculated at a pixel scale: radar reflectivities, for example, are integrated over a volume, so a DSD for the volume must be calculated or assumed. We present results of a study in which we have investigated the change of support problem with respect to the DSD. We have attempted to answer the following two questions. First, if a DSD measured at point scale is used to represent an area, how much error does this introduce? Second, how representative are areal DSDs calculated by QPE and NWP algorithms of the microphysical process happening inside the pixel of interest? We simulated fields of DSDs at two representative spatial resolutions: at the 2.1x2.1 km2 resolution of a typical NWP pixel, and at the 5x5 km2 resolution of a Global Precipitation Mission (GPM) satellite-based weather radar pixel. The simulation technique uses disdrometer network data and geostatistics to simulate the non-parametric DSD at 100x100 m2 resolution, conditioned by the measured DSD values. From these simulations, areal DSD measurements were derived and compared to point measurements of the DSD. The results show that the assumption that a point represents an area introduces error that increases with areal size and drop size and decreases with integration time. Further, the results show that current areal DSD estimation algorithms are not always representative of sub-grid DSDs. Idealised simulations of areal DSDs produced representative values for rain rate and radar reflectivity, but estimations of drop concentration and characteristic drop size that were often outside the sub-grid value ranges.

  17. Prediction of size distribution of Ag nanoparticles synthesized via gamma-ray radiolysis

    NASA Astrophysics Data System (ADS)

    Liang, Jia-liang; Shen, Sheng-wen; Ye, Sheng-ying; Ye, Lü-meng

    2015-09-01

    The spherical shape Ag nanoparticles synthesized via gamma-ray radiolysis were observed with the transmission electron microscope (TEM). Diameters of Ag nanoparticles were measured from the TEM photographs. Statistical analysis showed that the particle diameter complied with a linear-converted Poisson distribution. The distribution parameter, which was the average of diameters, was related to the ultraviolet-visible spectrum peak position of the nanosilver collosol. An empirical equation was established to predicting size distribution of Ag nanoparticles with the peak position. Nanosilver of different sizes could be synthesized by adjusting the intensity of γ-irradiation, the kind and the addition amount of the stabilizing agent. Because particle size affects the physiochemical properties of nanosilver material, results of this paper would be of practical significance for the application of nanosilver.

  18. Pore-size distribution in loamy soils: A comparison between microtomographic and capillarimetric determination methods

    NASA Astrophysics Data System (ADS)

    Shein, E. V.; Skvortsova, E. B.; Dembovetskii, A. V.; Abrosimov, K. N.; Il'in, L. I.; Shnyrev, N. A.

    2016-03-01

    Pore-size distribution in a soddy-podzolic silt loamy soil developing from mantle loesslike loam (Eutric Albic Retisol (Loamic, Cutanic)) was calculated from the water retention curve according to Jurin's equation and directly determined in microtomographic experiments. Rounded macropores with the diameter of their sections from 75 to 1000 μm predominate in horizontal sections if the studied soil samples. A larger part of the soil pores (>30-35%) belongs to micro- and nanopores, and they cannot be quantitatively determined by the tomographic method, because their sizes are smaller than the detection limit of the applied X-ray microtomography (8.75 μm per pixel). This leads to a significantly larger pore volume determined from the water retention curve in comparison with the "tomographic" pore volume. A comparative analysis of pore-size distribution curves obtained by these methods shows that the major regularities of the pore-size distribution in the range from 30 to 5000 μm are similar in both cases. Fine macropores and, partly, mesopores predominate. Common characteristics of the pore-size distribution curves obtained by these methods, including the coincidence of the peaks, attest to the validity of classical approaches, according to which the hydrology of soil pore space can be perceived as a physical model of cylindrical capillaries of different sizes with capillary-sorbed water.

  19. Effect Of Grain Size-Distribution And Nonthermal Ion Distribution On Dust Acoustic Solitons

    SciTech Connect

    Annou, K.; Annou, R.

    2005-10-31

    The investigation of the formation of non-linear coherent structures in dusty plasmas taking into account the dust size and non-thermal ion distributions is conducted. Conditions of the existence of solitons in terms of the Mach number, concentration of non-thermal ions, dust charge and the permeability of the grains are evaluated.

  20. Finite Size Effects on the Real-Space Pair Distribution Function of Nanoparticles

    SciTech Connect

    Gilbert, Benjamin

    2008-10-01

    The pair distribution function (PDF) method is a powerful approach for the analysis of the structure of nanoparticles. An important approximation used in nanoparticle PDF simulations is the incorporation of a form factor describing nanoparticle size and shape. The precise effect of the form factor on the PDF is determined by both particle shape and structure if these characteristics are both anisotropic and correlated. The correct incorporation of finite size effects is important for distinguishing and quantifying the structural consequences of small particle size in nanomaterials.

  1. On the asteroid belt's orbital and size distribution

    NASA Astrophysics Data System (ADS)

    Gladman, Brett J.; Davis, Donald R.; Neese, Carol; Jedicke, Robert; Williams, Gareth; Kavelaars, J. J.; Petit, Jean-Marc; Scholl, Hans; Holman, Matthew; Warrington, Ben; Esquerdo, Gil; Tricarico, Pasquale

    2009-07-01

    For absolute magnitudes greater than the current completeness limit of H-magnitude ∼15 the main asteroid belt's size distribution is imperfectly known. We have acquired good-quality orbital and absolute H-magnitude determinations for a sample of small main-belt asteroids in order to study the orbital and size distribution beyond H = 15, down to sub-kilometer sizes (H > 18). Based on six observing nights over a 11-night baseline we have detected, measured photometry for, and linked observations of 1087 asteroids which have one-week time baselines or more. The linkages allow the computation of full heliocentric orbits (as opposed to statistical distances determined by some past surveys). Judged by known asteroids in the field the typical uncertainty in the (a / e / i) orbital elements is less than 0.03 AU/0.03/0.5°. The distances to the objects are sufficiently well known that photometric uncertainties (of 0.3 magnitudes or better) dominate the error budget of their derived H-magnitudes. The detected asteroids range from HR = 12- 22 and provide a set of objects down to sizes below 1 km in diameter. We find an on-sky surface density of 210 asteroids per square degree in the ecliptic with opposition magnitudes brighter than mR = 23, with the cumulative number of asteroids increasing by a factor of 100.27/mag from mR = 18 down to the mR ≃ 23.5 limit of our survey. In terms of absolute H magnitudes, we find that beyond H = 15 the belt exhibits a constant power-law slope with the number increasing proportional to 100.30H from H ≃ 15 to 18, after which incompleteness begins in the survey. Examining only the subset of detections inside 2.5 AU, we find weak evidence for a mildly shallower slope for H = 15- 19.5. We provide the information necessary such that anyone wishing to model the main asteroid belt can compare a detailed model to our detected sample.

  2. Size and composition distribution of fine particulate matter emitted from wood burning, meat charbroiling, and cigarettes

    SciTech Connect

    Kleeman, M.J.; Schauer, J.J.; Cass, G.R.

    1999-10-15

    A dilution source sampling system is augmented to measure the size-distributed chemical composition of fine particle emissions from air pollution sources. Measurements are made using a laser optical particle counter (OPC), a differential mobility analyzer/condensation nucleus counter (DMA/CNC) combination, and a pair of microorifice uniform deposit impactors (MOUDIs). The sources tested with this system include wood smoke (pine, oak, eucalyptus), meat charbroiling, and cigarettes. The particle mass distributions from all wood smoke sources have a single mode that peaks at approximately 0.1--0.2 {micro}m particle diameter. The smoke from meat charbroiling shows a major peak in the particle mass distribution at 0.1--0.2 {micro}m particle diameter, with some material present at larger particle sizes. Particle mass distributions from cigarettes peak between 0.3 and 0.4 {micro}m particle diameter. Chemical composition analysis reveals that particles emitted from the sources tested here are largely composed of organic compounds. Noticeable concentrations of elemental carbon are found in the particles emitted from wood burning. The size distributions of the trace species emissions from these sources also are presented, including data for Na, K, Ti, Fe, Br, Ru, Cl, Al, Zn, Ba, Sr, V, Mn, Sb, La, Ce, as well as sulfate, nitrate, and ammonium ion when present in statistically significant amounts. These data are intended for use with air quality models that seek to predict the size distribution of the chemical composition of atmospheric fine particles.

  3. Digital grain-size analysis based on autocorrelation algorithm

    NASA Astrophysics Data System (ADS)

    Cheng, Zhixuan; Liu, Haijiang

    2015-08-01

    Grain size is one of the most important parameters in geology and coastal engineering. However, all traditional methods are time consuming, laborious, and expensive. In this study, the autocorrelation technique, which was first expounded by Rubin (2004), was extended to estimate the size of well-sorted sediments and the grain-size distribution of mixed-size sediments. Long and intermediate axes of well-sorted sediments ranging from 1 to 20 mm obtained from applying the autocorrelation method are compared with the corresponding results measured using a vernier caliper. Using the autocorrelation technique, the sediment mean size was calculated and was found to compare better with point counts than sieving. Regarding the mixed-size sediment, a nonlinear programming method, which is different from the conventional 'least-squares with non-negativity' method, the kernel density method, and the maximum entropy method, was used to obtain the representative grain sizes and associated sediment inherent parameters, such as mean diameter, median diameter, sorting, skewness, and kurtosis. Image pre-processing was used in the present analysis to enhance the contrast of the recorded image, and a conversion method applied to take into account the difference between the two-dimensional digital image method and the three-dimensional sieving method. Using the modified fitting points and the improved Gaussian function fitting method, the cumulative grain-size distribution curve and the probability density curve of the mixed-size sediments were obtained. The enhanced autocorrelation technique that was developed from the traditional 'look-up-catalogue' approach provided a more accurate estimation of the grain-size distribution, as well as the relevant physical parameters of the mixed-size sediment.

  4. Characterizing Particle Size Distributions of Crystalline Silica in Gold Mine Dust

    PubMed Central

    Chubb, Lauren G.; Cauda, Emanuele G.

    2017-01-01

    Dust containing crystalline silica is common in mining environments in the U.S. and around the world. The exposure to respirable crystalline silica remains an important occupational issue and it can lead to the development of silicosis and other respiratory diseases. Little has been done with regard to the characterization of the crystalline silica content of specific particle sizes of mine-generated dust. Such characterization could improve monitoring techniques and control technologies for crystalline silica, decreasing worker exposure to silica and preventing future incidence of silicosis. Three gold mine dust samples were aerosolized in a laboratory chamber. Particle size-specific samples were collected for gravimetric analysis and for quantification of silica using the Microorifice Uniform Deposit Impactor (MOUDI). Dust size distributions were characterized via aerodynamic and scanning mobility particle sizers (APS, SMPS) and gravimetrically via the MOUDI. Silica size distributions were constructed using gravimetric data from the MOUDI and proportional silica content corresponding to each size range of particles collected by the MOUDI, as determined via X-ray diffraction and infrared spectroscopic quantification of silica. Results indicate that silica does not comprise a uniform proportion of total dust across all particle sizes and that the size distributions of a given dust and its silica component are similar but not equivalent. Additional research characterizing the silica content of dusts from a variety of mine types and other occupational environments is necessary in order to ascertain trends that could be beneficial in developing better monitoring and control strategies. PMID:28217139

  5. Characterizing Particle Size Distributions of Crystalline Silica in Gold Mine Dust.

    PubMed

    Chubb, Lauren G; Cauda, Emanuele G

    2017-01-01

    Dust containing crystalline silica is common in mining environments in the U.S. and around the world. The exposure to respirable crystalline silica remains an important occupational issue and it can lead to the development of silicosis and other respiratory diseases. Little has been done with regard to the characterization of the crystalline silica content of specific particle sizes of mine-generated dust. Such characterization could improve monitoring techniques and control technologies for crystalline silica, decreasing worker exposure to silica and preventing future incidence of silicosis. Three gold mine dust samples were aerosolized in a laboratory chamber. Particle size-specific samples were collected for gravimetric analysis and for quantification of silica using the Microorifice Uniform Deposit Impactor (MOUDI). Dust size distributions were characterized via aerodynamic and scanning mobility particle sizers (APS, SMPS) and gravimetrically via the MOUDI. Silica size distributions were constructed using gravimetric data from the MOUDI and proportional silica content corresponding to each size range of particles collected by the MOUDI, as determined via X-ray diffraction and infrared spectroscopic quantification of silica. Results indicate that silica does not comprise a uniform proportion of total dust across all particle sizes and that the size distributions of a given dust and its silica component are similar but not equivalent. Additional research characterizing the silica content of dusts from a variety of mine types and other occupational environments is necessary in order to ascertain trends that could be beneficial in developing better monitoring and control strategies.

  6. Size distributions of circular molecules in plant mitochondrial DNAs.

    PubMed

    Bailey-Serres, J; Leroy, P; Jones, S S; Wahleithner, J A; Wolstenholme, D R

    1987-01-01

    Some physicochemical properties of the mitochondrial DNAs (mtDNA) from plants of flax, broad bean and mung bean, and from tissue culture cells of jimson weed, soybean, petunia and tobacco were determined. Circular molecules were observed in electron microscope preparations of each mtDNA. In soybean, petunia, broad bean and mung bean mtDNAs, the circular molecules had a continuous distribution of lengths (ranges between 1 to 36 kb, and 1 to 126 kb), heavily skewed toward smaller molecules. Eighty-six percent of the flax circular molecules were from 27 to 54 kb in size, and 78% of the jimson weed circular molecules were from 4 to 15 kb. Replicative forms of 1.2-1.6 kb circular molecules were observed in electron microscope preparations of broad bean mtDNA.

  7. Particle size distribution and metal content in street sediments

    SciTech Connect

    Viklander, M.

    1998-08-01

    Sediments that had accumulated during the winter season, and which were left at the surface when the snow had melted, were studied with regard to physical and chemical characteristics. The investigation was carried out in the city of Luleaa, which is located in northern Sweden. Sediment samples were collected in the city center and in a housing area at streets with different traffic loads. The results showed that the amount of the sediments at a street surface was evidently affected by the presence of a sidewalk. The street with a sidewalk accumulated much more sediment than the street without a sidewalk. Both of these streets had approximately the same traffic load. The sidewalk also affected the particle size distribution. The content of heavy metals in the sediments varied with the traffic load and the area type. The highest concentration of cadmium, lead, and zinc was found in the street with the highest traffic load.

  8. Particle size distribution dynamics during precipitative softening: constant solution composition.

    PubMed

    Nason, Jeffrey A; Lawler, Desmond F

    2008-08-01

    In the treatment of surface water for potable use, precipitative coagulation (e.g., lime softening, alum or iron sweep coagulation) is widely utilized prior to particle removal processes. The particle size distribution (PSD) formed during such processes is a prime determinant of the removal efficiency for suspended and dissolved contaminants, but little is known quantitatively about how PSDs change by simultaneous precipitation and flocculation. Using precipitative softening as an example, detailed measurements of the PSD (using electronic particle counting) were made during precipitation of CaCO(3) under conditions of constant solution composition. Examination of the time-varying PSDs revealed dramatic changes resulting from nucleation, crystal growth, and flocculation. The influence of the saturation ratio, seed concentration, and mixing intensity on those processes was quantified. Implications with respect to the design and operation of water treatment facilities are discussed.

  9. Influence of particle size distribution on nanopowder cold compaction processes

    NASA Astrophysics Data System (ADS)

    Boltachev, G.; Volkov, N.; Lukyashin, K.; Markov, V.; Chingina, E.

    2017-06-01

    Nanopowder uniform and uniaxial cold compaction processes are simulated by 2D granular dynamics method. The interaction of particles in addition to wide-known contact laws involves the dispersion forces of attraction and possibility of interparticle solid bridges formation, which have a large importance for nanopowders. Different model systems are investigated: monosized systems with particle diameter of 10, 20 and 30 nm; bidisperse systems with different content of small (diameter is 10 nm) and large (30 nm) particles; polydisperse systems corresponding to the log-normal size distribution law with different width. Non-monotone dependence of compact density on powder content is revealed in bidisperse systems. The deviations of compact density in polydisperse systems from the density of corresponding monosized system are found to be minor, less than 1 per cent.

  10. Raindrop size distributions and storm classification in Mexico City

    NASA Astrophysics Data System (ADS)

    Amaro-Loza, Alejandra; Pedrozo-Acuña, Adrián; Agustín| Breña-Naranjo, José

    2017-04-01

    Worldwide, the effects of urbanization and land use change have caused alterations to the hydrological response of urban catchments. This observed phenomenon implies high resolution measurements of rainfall patterns. The work provides the first dataset of raindrop size distributions and storm classification, among others, across several locations of Mexico City. Data were derived from a recent established network of laser optical disdrometers (LOD) and retrieving measurements of rainrate, reflectivity, number of drops, drop diameter & velocity, and kinetic energy, at a 1-minute resolution. Moreover, the comparison of hourly rainfall patterns revealed the origin and classification of storms into three types: stratiform, transition and convective, by means of its corresponding reflectivity and rainrate relationship (Z-R). Finally, a set of rainfall statistics was applied to evaluate the performance of the LOD disdrometer and weighing precipitation gauge (WPG) data at different aggregated timescales. It was found that WPG gauge estimates remain below the precipitation amounts measured by the LOD.

  11. Particle-size distribution in soils of West Antarctica

    NASA Astrophysics Data System (ADS)

    Abakumov, E. V.

    2010-03-01

    The particle-size distribution in soils sampled near Russian polar stations in West Antarctica has been studied. It is shown that the soils of the Subantarctic zone (the Bellingshausen Station on King George Island) are characterized by a higher content of silt and clay in the fine earth fraction and by a higher content of the fine earth fraction in comparison with the soils of the proper Antarctic tundra barrens near the Lenin-gradskaya Station and the Antarctic cold desert near the Russkaya Station. In the latter soils, the content of rock fragments is higher than that in the soils of the Antarctic tundra barrens. In the soils of the tundra barrens, a considerable accumulation of fine earth may take place in large cavities (hollows) on the stony bedrock surface. Desert pavements are formed in both types of Antarctic landscapes.

  12. Monte Carlo predictions of DNA fragment-size distributions for large sizes after HZE particle irradiation

    NASA Technical Reports Server (NTRS)

    Ponomarev, A. L.; Cucinotta, F. A.; Sachs, R. K.; Brenner, D. J.

    2001-01-01

    DSBs (double-strand breaks) produced by densely ionizing space radiation are not located randomly in the genome: recent data indicate DSB clustering along chromosomes. DSB clustering at large scales, from >100 Mbp down to approximately 2 kbp, is modeled using a Monte-Carlo algorithm. A random-walk model of chromatin is combined with a track model, that predicts the radial distribution of energy from an ion, and the RLC (randomly-located-clusters) formalism, in software called DNAbreak. This model generalizes the random-breakage model, whose broken-stick fragment-size distribution is applicable to low-LET radiation. DSB induction due to track interaction with the DNA volume depends on the radiation quality parameter Q. This dose-independent parameter depends only weakly on LET. Multi-track, high-dose effects depend on the cluster intensity parameter lambda, proportional to fluence as defined by the RLC formalism. After lambda is determined by a numerical experiment, the model reduces to one adjustable parameter Q. The best numerical fits to the experimental data, determining Q, are obtained. The knowledge of lambda and Q allows us to give biophysically based extrapolations of high-dose DNA fragment-size data to low doses or to high LETs.

  13. Monte Carlo predictions of DNA fragment-size distributions for large sizes after HZE particle irradiation

    NASA Technical Reports Server (NTRS)

    Ponomarev, A. L.; Cucinotta, F. A.; Sachs, R. K.; Brenner, D. J.

    2001-01-01

    DSBs (double-strand breaks) produced by densely ionizing space radiation are not located randomly in the genome: recent data indicate DSB clustering along chromosomes. DSB clustering at large scales, from >100 Mbp down to approximately 2 kbp, is modeled using a Monte-Carlo algorithm. A random-walk model of chromatin is combined with a track model, that predicts the radial distribution of energy from an ion, and the RLC (randomly-located-clusters) formalism, in software called DNAbreak. This model generalizes the random-breakage model, whose broken-stick fragment-size distribution is applicable to low-LET radiation. DSB induction due to track interaction with the DNA volume depends on the radiation quality parameter Q. This dose-independent parameter depends only weakly on LET. Multi-track, high-dose effects depend on the cluster intensity parameter lambda, proportional to fluence as defined by the RLC formalism. After lambda is determined by a numerical experiment, the model reduces to one adjustable parameter Q. The best numerical fits to the experimental data, determining Q, are obtained. The knowledge of lambda and Q allows us to give biophysically based extrapolations of high-dose DNA fragment-size data to low doses or to high LETs.

  14. Measurements of Gas Bubble Size Distributions in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Riemer, Bernie; Abdou, Ashraf A

    2012-01-01

    ABSTRACT Pressure waves created in liquid mercury pulsed spallation targets have been shown to induce cavitation damage on the target container. One way to mitigate such damage would be to absorb the pressure pulse energy into a dispersed population of small bubbles, however, measuring such a population in mercury is difficult since it is opaque and the mercury is involved in a turbulent flow. Ultrasonic measurements have been attempted on these types of flows, but the flow noise can interfere with the measurement, and the results are unverifiable and often unrealistic. Recently, a flow loop was built and operated at Oak Ridge National Labarotory to assess the capability of various bubbler designs to deliver an adequate population of bubbles to mitigate cavitation damage. The invented diagnostic technique involves flowing the mercury with entrained gas bubbles in a steady state through a horizontal piping section with a glass-window observation port located on the top. The mercury flow is then suddenly stopped and the bubbles are allowed to settle on the glass due to buoyancy. Using a bright-field illumination and a high-speed camera, the arriving bubbles are detected and counted, and then the images can be processed to determine the bubble populations. After using this technique to collect data on each bubbler, bubble size distributions were built for the purpose of quantifying bubbler performance, allowing the selection of the best bubbler options. This paper presents the novel procedure, photographic technique, sample visual results and some example bubble size distributions. The best bubbler options were subsequently used in proton beam irradiation tests performed at the Los Alamos National Laboratory. The cavitation damage results from the irradiated test plates in contact with the mercury are available for correlation with the bubble populations. The most effective mitigating population can now be designed into prototypical geometries for implementation into

  15. A possible divot in the Kuiper belt's scattered-object size distribution

    NASA Astrophysics Data System (ADS)

    Shankman, C.; Kavelaars, J.; Gladman, B.; Petit, J.

    2014-07-01

    The formation and evolution history of the Solar System, while not directly accessible, has measurable signatures in the present-day size distributions of the Trans-Neptunian Object (TNO) populations. The form of the size distribution is modelled as a power law with number going as size to some characteristic slope. Recent works have shown that a single power law does not match the observations across all sizes; the power law breaks to a different form [1, 2, 3]. The large- size objects record the accretion history, while the small-size objects record the collision history. The changes of size-distribution shape and slope as one moves from 'large' to 'medium' to 'small' KBOs are the signature needed to constrain the formation and collision history of the Solar System. The scattering TNOs are those TNOs undergoing strong (scattering) interactions Neptune. The scattering objects can come to pericentre in the giant planet region. This close-in pericentre passage allows for the observation of smaller objects, and thus for the constraint of the small-size end of the size distribution. Our recent analysis of the Canada France Ecliptic Plane Survey's (CFEPS) scattering objects revealed an exciting potential form for the scattering object size distribution - a divot (see Figure). Our divot (a sharp drop in the number of objects per unit size which then returns at a potentially different slope) matches our observations well and can simultaneously explain observed features in other inclined (so-called "hot") Kuiper Belt populations. In this scenario all of the hot populations would share the same source and have been implanted in the outer solar system through scattering processes. If confirmed, our divot would represent a new exciting paradigm for the formation history of the Kuiper Belt. Here we present the results of an extension of our previous work to include a new, deeper, Kuiper Belt survey. By the addition of two new faint scattering objects from this survey which

  16. Airborne Measurements of Aerosol Size Distributions During PACDEX

    NASA Astrophysics Data System (ADS)

    Rogers, D. C.; Gandrud, B.; Campos, T.; Kok, G.; Stith, J.

    2007-12-01

    The Pacific Dust Experiment (PACDEX) is an airborne project that attempts to characterize the indirect aerosol effect by tracing plumes of dust and pollution across the Pacific Ocean. This project occurred during April-May 2007 and used the NSF/NCAR HIAPER research aircraft. When a period of strong generation of dust particles and pollution was detected by ground-based and satellite sensors, then the aircraft was launched from Colorado to Alaska, Hawaii, and Japan. Its mission was to intercept and track these plumes from Asia, across the Pacific Ocean, and ultimately to the edges of North America. For more description, see the abstract by Stith and Ramanathan (this conference) and other companion papers on PACDEX. The HIAPER aircraft carried a wide variety of sensors for measuring aerosols, cloud particles, trace gases, and radiation. Sampling was made in several weather regimes, including clean "background" air, dust and pollution plumes, and regions with cloud systems. Altitude ranges extended from 100 m above the ocean to 13.4 km. This paper reports on aerosol measurements made with a new Ultra-High Sensitivity Aerosol Spectrometer (UHSAS), a Radial Differential Mobility Analyzer (RDMA), a water-based CN counter, and a Cloud Droplet Probe (CDP). These cover the size range 10 nm to 10 um diameter. In clear air, dust was detected with the UHSAS and CDP. Polluted air was identified with high concentrations of carbon monoxide, ozone, and CN. Aerosol size distributions will be presented, along with data to define the context of weather regimes.

  17. THE EFFECT OF THE DUST SIZE DISTRIBUTION ON ASTEROID POLARIZATION

    SciTech Connect

    Masiero, Joseph; Hartzell, Christine; Scheeres, Daniel J. E-mail: christine.hartzell@colorado.edu

    2009-12-15

    We have developed a theoretical description of how of an asteroid's polarization-phase curve will be affected by the removal of the dust from the surface due to a size-dependent phenomenon such as radiation pressure-driven escape of levitated particles. We test our calculations against new observations of four small (D {approx} 1 km) near-Earth asteroids (NEAs; (85236), (142348), (162900), and 2006 SZ{sub 217}) obtained with the Dual Beam Imaging Polarimeter on the University of Hawaii's 2.2 m telescope, as well as previous observations of (25143) Itokawa and (433) Eros. We find that the polarization of the light reflected from an asteroid is controlled by the mineralogical and chemical composition of the surface and is independent of dust particle. The relation between the slope of the polarization-phase curve beyond the inversion angle and the albedo of an asteroid is thus independent of the surface regolith size distribution and is valid for both Main Belt and NEAs.

  18. Concentrations and size distributions of Antarctic stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Ferry, G. V.; Pueschel, R. F.; Neish, E.; Schultz, M.

    1989-01-01

    Particle Measuring Systems laser particle spectrometer (ASAS-X and FSSP) probes were used to measure aerosol particle concentrations and size distributions during 11 ER-2 flights between Punta Arenas (53 deg S) and Antarctica (up to 72 deg S) from August 17 to September 22, 1987. The time resolution was 10 s, corresponding to a spatial resolution of 2 km. The data were divided into two size classes (0.05-0.25 and 0.53-5.5 micron radius) to separate the small particle from the coarse particle populations. Results show that the small-particle concentrations are typical for a background aerosol during volcanic quiescence. This concentration is generally constant along a flight track; in only one instance a depletion of small particles during a polar stratospheric cloud (PSC) encounter was measured, suggesting a nucleation of type I PSC particles on background aerosols. Temporary increases of the coarse particle concentrations indicated the presence of tenuous polar stratospheric clouds that were encountered most frequently at the southernmost portion of a flight track and when the aircraft descended to lower altitudes. During 'particle events', particle modes were found at 0.6-micron radius, corresponding to type I PSCs, and occasionally, at 2.0-micron radius corresponding to type II PSCs.

  19. Polyester scaffolds with bimodal pore size distribution for tissue engineering.

    PubMed

    Sosnowski, Stanislaw; Woźniak, Piotr; Lewandowska-Szumieł, Małgorzata

    2006-06-16

    This paper presents a method for the preparation of porous poly(L-lactide)/poly[(L-lactide)-co-glycolide] scaffolds for tissue engineering. Scaffolds were prepared by a mold pressing-salt leaching technique from structured microparticles. The total porosity was in the range 70-85%. The pore size distribution was bimodal. Large pores, susceptible for osteoblasts growth and proliferation had the dimensions 50-400 microm. Small pores, dedicated to the diffusion of nutrients or/and metabolites of bone forming cells, as well as the products of hydrolysis of polyesters from the walls of the scaffold, had sizes in the range 2 nm-5 microm. The scaffolds had good mechanical strength (compressive modulus equal to 41 MPa and a strength of 1.64 MPa for 74% porosity). Scaffolds were tested in vitro with human osteoblast-like cells (MG-63). It was found that the viability of cells seeded within the scaffolds obtained using the mold pressing-salt leaching technique from structured microparticles was better when compared to cells cultured in scaffolds obtained by traditional methods. After 34 d of culture, cells within the tested scaffolds were organized in a tissue-like structure. Photos of section of macro- and mesoporous PLLA/PLGA scaffold containing 50 wt.-% of PLGA microspheres after 34 d of culture. Dark spots mark MG-63 cells, white areas belong to the scaffold. The specimen was stained with haematoxylin/eosin. Bar = 100 microm.

  20. Comparison of Raindrop Size Distribution Measurements by Collocated Disdrometers

    NASA Technical Reports Server (NTRS)

    Tokay, Ali; Petersen, Walter A.; Gatlin, Patrick; Wingo, Matthew

    2013-01-01

    An impact-type Joss-Waldvogel disdrometer (JWD), a two-dimensional video disdrometer (2DVD), and a laser optical OTT Particle Size and Velocity (PARSIVEL) disdrometer (PD) were used to measure the raindrop size distribution (DSD) over a 6-month period in Huntsville, Alabama. Comparisons indicate event rain totals for all three disdrometers that were in reasonable agreement with a reference rain gauge. In a relative sense, hourly composite DSDs revealed that the JWD was more sensitive to small drops (,1 mm), while the PD appeared to severely underestimate small drops less than 0.76mm in diameter. The JWD and 2DVD measured comparable number concentrations of midsize drops (1-3mm) and large drops (3-5 mm), while the PD tended to measure relatively higher drop concentrations at sizes larger than 2.44mm in diameter. This concentration disparity tended to occur when hourly rain rates and drop counts exceeded 2.5mm/h and 400/min, respectively. Based on interactions with the PD manufacturer, the partially inhomogeneous laser beam is considered the cause of the PD drop count overestimation. PD drop fall speeds followed the expected terminal fall speed relationship quite well, while the 2DVD occasionally measured slower drops for diameters larger than 2.4mm, coinciding with events where wind speeds were greater than 4m/s. The underestimation of small drops by the PD had a pronounced effect on the intercept and shape of parameters of gamma-fitted DSDs, while the overestimation of midsize and larger drops resulted in higher mean values for PD integral rain parameters

  1. Changes in tropical precipitation cluster size distributions under global warming

    NASA Astrophysics Data System (ADS)

    Neelin, J. D.; Quinn, K. M.

    2016-12-01

    The total amount of precipitation integrated across a tropical storm or other precipitation feature (contiguous clusters of precipitation exceeding a minimum rain rate) is a useful measure of the aggregate size of the disturbance. To establish baseline behavior in current climate, the probability distribution of cluster sizes from multiple satellite retrievals and National Center for Environmental Prediction (NCEP) reanalysis is compared to those from Coupled Model Intercomparison Project (CMIP5) models and the Geophysical Fluid Dynamics Laboratory high-resolution atmospheric model (HIRAM-360 and -180). With the caveat that a minimum rain rate threshold is important in the models (which tend to overproduce low rain rates), the models agree well with observations in leading properties. In particular, scale-free power law ranges in which the probability drops slowly with increasing cluster size are well modeled, followed by a rapid drop in probability of the largest clusters above a cutoff scale. Under the RCP 8.5 global warming scenario, the models indicate substantial increases in probability (up to an order of magnitude) of the largest clusters by the end of century. For models with continuous time series of high resolution output, there is substantial spread on when these probability increases for the largest precipitation clusters should be detectable, ranging from detectable within the observational period to statistically significant trends emerging only in the second half of the century. Examination of NCEP reanalysis and SSMI/SSMIS series of satellite retrievals from 1979 to present does not yield reliable evidence of trends at this time. The results suggest improvements in inter-satellite calibration of the SSMI/SSMIS retrievals could aid future detection.

  2. Event-based total suspended sediment particle size distribution model

    NASA Astrophysics Data System (ADS)

    Thompson, Jennifer; Sattar, Ahmed M. A.; Gharabaghi, Bahram; Warner, Richard C.

    2016-05-01

    One of the most challenging modelling tasks in hydrology is prediction of the total suspended sediment particle size distribution (TSS-PSD) in stormwater runoff generated from exposed soil surfaces at active construction sites and surface mining operations. The main objective of this study is to employ gene expression programming (GEP) and artificial neural networks (ANN) to develop a new model with the ability to more accurately predict the TSS-PSD by taking advantage of both event-specific and site-specific factors in the model. To compile the data for this study, laboratory scale experiments using rainfall simulators were conducted on fourteen different soils to obtain TSS-PSD. This data is supplemented with field data from three construction sites in Ontario over a period of two years to capture the effect of transport and deposition within the site. The combined data sets provide a wide range of key overlooked site-specific and storm event-specific factors. Both parent soil and TSS-PSD in runoff are quantified by fitting each to a lognormal distribution. Compared to existing regression models, the developed model more accurately predicted the TSS-PSD using a more comprehensive list of key model input parameters. Employment of the new model will increase the efficiency of deployment of required best management practices, designed based on TSS-PSD, to minimize potential adverse effects of construction site runoff on aquatic life in the receiving watercourses.

  3. Using radial NMR profiles to characterize pore size distributions

    NASA Astrophysics Data System (ADS)

    Deriche, Rachid; Treilhard, John

    2012-02-01

    Extracting information about axon diameter distributions in the brain is a challenging task which provides useful information for medical purposes; for example, the ability to characterize and monitor axon diameters would be useful in diagnosing and investigating diseases