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All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

CLUMPY GALAXIES IN CANDELS. I. THE DEFINITION OF UV CLUMPS AND THE FRACTION OF CLUMPY GALAXIES AT 0.5 < z < 3

Although giant clumps of stars are thought to be crucial to galaxy formation and evolution, the most basic demographics of clumps are still uncertain, mainly because the definition of clumps has not been thoroughly discussed. In this paper, we carry out a study of the basic demographics of clumps in star-forming galaxies at 0.5 < z < 3, using our proposed physical definition that UV-bright clumps are discrete star-forming regions that individually contribute more than 8% of the rest-frame UV light of their galaxies. Clumps defined this way are significantly brighter than the H II regions of nearby large spiral galaxies, either individually or blended, when physical spatial resolution and cosmological dimming are considered. Under this definition, we measure the fraction of star-forming galaxies that have at least one off-center clump (f {sub clumpy}) and the contributions of clumps to the rest-frame UV light and star formation rate (SFR) of star-forming galaxies in the CANDELS/GOODS-S and UDS fields, where our mass-complete sample consists of 3239 galaxies with axial ratio q > 0.5. The redshift evolution of f {sub clumpy} changes with the stellar mass (M {sub *}) of the galaxies. Low-mass (log (M {sub *}/M {sub ☉}) < 9.8) galaxies keep an almost constant f {sub clumpy} of ∼60% from z ∼ 3 to z ∼ 0.5. Intermediate-mass and massive galaxies drop their f {sub clumpy} from 55% at z ∼ 3 to 40% and 15%, respectively, at z ∼ 0.5. We find that (1) the trend of disk stabilization predicted by violent disk instability matches the f {sub clumpy} trend of massive galaxies; (2) minor mergers are a viable explanation of the f {sub clumpy} trend of intermediate-mass galaxies at z < 1.5, given a realistic observability timescale; and (3) major mergers are unlikely responsible for the f {sub clumpy} trend in all masses at z < 1.5. The clump contribution to the rest-frame UV light of star-forming galaxies shows a broad peak around galaxies with log (M {sub *}/M {sub ☉}) ∼ 10.5 at all redshifts. The clump contribution in the intermediate-mass and massive galaxies is possibly linked to the molecular gas fraction of the galaxies. The clump contribution to the SFR of star-forming galaxies, generally around 4%-10%, also shows dependence on the galaxy M {sub *}, but for a given galaxy M {sub *}, its dependence on the redshift is mild.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Diurnal observations of basal stem CO2 efflux in three canopy dominant trees in the central Amazon

We explored mechanisms responsible for disturbance-induced shifts in carbon metabolism in forests north of Manaus, Brazil (S2º 38' 17", W60º 09' 25"), using data from a selective logging experiment (BIONTE). BIONTE (the BIOmass and NuTrient Experiment) selective logging treatments were initiated in the mid-1980s and comprised variable removal of commercial tree (not total) species basal area (T1 =32%, T2 = 42%, T3 = 69%), and control plots with no logging (T0). Raw data including tree base diameter (Db), CO2 concentration versus time inside a static stem chamber, and wood density were used to derive stem respiration rates (Rw), wood production rates (Pw), and wood carbon use efficiency (CUE). Changes in tree base diameter (Db; measured at 1.3 m height, or above the buttresses) was used to calculate wood production for individual trees (Pw). Wood density enabled calculation of stem growth rate in the same units as stem respiration (mmol C m-2 s-1). Four trees were randomly selected from five tree growth rate classes for each treatment block, for a total of 20 trees per treatment block, or 80 trees total from the BIONTE plots. Each of the 80 trees selected for the Rw study were outfitted with dendrometer bands (da Silva et al. 2002). Stem respiration was measured using the method described in Chambers et al. (2004). Briefly, an infra-red gas analyzer (LiCor 820) was operated as a closed dynamic chamber with a flow rate of 1.0 L min-1. Polyvinyl chloride (PVC) semi-cylindrical chambers (250–400 mL) were secured to the tree stem near the dendrometer bands using nylon straps. The measurement interval spanned 1–2 min, and the CO2 flux from the stem of each tree was quantified using the enclosed stem area and slope of the stem CO2 concentration versus time.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1993

Thermal history effects on electrical relaxation and conductivity for potassium silicate glass with low alkali concentrations

Electrical response measurements from 10 Hz to 100 kHz between 120 and 540 C were made on potassium-silicate glasses with alkali oxide contents of 2, 3, 5 and 10 mol percent. Low alkali content glasses were chosen in order to try to reduce the Coulombic interactions between alkali ions to the point that frozen structural effects from the glass could be observed. Conductivity and electrical relaxation responses for both annealed and quenched glasses of the same composition were compared. Lower DC conductivity (sigma(sub DC)) activation energies were measured for the quenched compared to the annealed glasses. The two glasses with the lowest alkali contents exhibited a non-Arrhenius concave up curvature in the log(sigma(sub DC)) against 1/T plots, which decreased upon quenching. A sharp decrease in sigma(sub DC) was observed for glasses containing K2O concentrations of 5 mol percent or less. The log modulus loss peak (M'') maximum frequency plots against 1/T all showed Arrhenius behavior for both annealed and quenched samples. The activation energies for these plots closely agreed with the sigma(sub DC) activation energies. A sharp increase in activation energy was observed for both series as the potassium oxide concentration decreased. Changes in the electrical response are attributed to structural effects due to different alkali concentrations. Differences between the annealed and quenched response are linked to a change in the distribution of activation energies (DAE).

Angel, Paul W.↗
NASA NTRS1982

The influence of varied gravito-inertial fields on the cardiac response of orb-weaving spiders

The Gz transfer function was described for the orb weaving spider A. sericatus. The functional relationship between the heartrate and the intensity of G is linear in the form of: Y = a Log Gz-1 +k. The heartrate in unrestrained animals was recorded by a laser plethysmograph developed specifically for this purpose. Following a control, sample heartrate were taken postrotation between 1.001 and 1.5 Gz in 6 steps. The underlying distribution of heartrates does not appear significantly different from a Gaussian distribution. A method of varnishing the legs of the spider was developed. This was done in order to compromise the lyriform organs, especially those located on the patellae. The lyriform organ is hypothesized to serve the receptor role in the transduction of gravity related stimuli. In preliminary animals the Gz function, post varnishing of the patellae, appears to be changed in the direction of poorer discrimination. We also observed that the resting heartrate following the varnish procedure is substantially increased.

Finck, A.↗
DOE OSTI2024

Characterization of sub-micrometre-sized voids in fixed human brain tissue using scanning X-ray microdiffraction

Using a 5 µm-diameter X-ray beam, we collected scanning X-ray microdiffraction in both the small-angle (SAXS) and the wide-angle (WAXS) regimes from thin sections of fixed human brain tissue from Alzheimer's subjects. The intensity of scattering in the SAXS regime of these patterns exhibits essentially no correlation with the observed intensity in the WAXS regime, indicating that the structures responsible for these two portions of the diffraction patterns, which reflect different length scales, are distinct. SAXS scattering exhibits a power-law behavior in which the log of intensity decreases linearly with the log of the scattering angle. The slope of the log–log curve is roughly proportional to the intensity in the SAXS regime and, surprisingly, inversely proportional to the intensity in the WAXS regime. We interpret these observations as being due to the presence of sub-micrometre-sized voids formed during dehydration of the fixed tissue. The SAXS intensity is due largely to scattering from these voids, while the WAXS intensity derives from the secondary structures of macromolecular material surrounding the voids. The ability to detect and map the presence of voids within thin sections of fixed tissue has the potential to provide novel information on the degradation of human brain tissue in neurodegenerative diseases.

Chemistry↗
DOE OSTI2014

NGC 1365: A low column density state unveiling a low ionization disk wind

We present the time-resolved spectral analysis of the XMM-Newton data of NGC 1365 collected during one XMM-Newton observation, which caught this 'changing-look' active galactic nucleus in a high flux state characterized also by a low column density (N {sub H} ∼ 10{sup 22} cm{sup –2}) of the X-ray absorber. During this observation, the low-energy photoelectric cut-off is at about ∼1 keV and the primary continuum can be investigated with the XMM-Newton-RGS data, which show strong spectral variability that can be explained as a variable low N {sub H} that decreased from N {sub H} ∼ 10{sup 23} cm{sup –2} to 10{sup 22} cm{sup –2} in a 100 ks timescale. The spectral analysis of the last segment of the observation revealed the presence of several absorption features that can be associated with an ionized (log ξ ∼ 2 erg cm s{sup –1}) outflowing wind (v {sub out} ∼ 2000 km s{sup –1}). We detected for the first time a possible P-Cygni profile of the Mg XII Lyα line associated with this mildly ionized absorber indicative of a wide angle outflowing wind. We suggest that this wind is a low ionization zone of the highly ionized wind present in NGC 1365, which is responsible for the iron K absorption lines and is located within the variable X-ray absorber. At the end of the observation, we detected a strong absorption line at E ∼ 0.76 keV most likely associated with a lower ionization zone of the absorber (log ξ ∼ 0.2 erg cm s{sup –1}, N {sub H} ∼ 10{sup 22} cm{sup –2}), which suggests that the variable absorber in NGC 1365 could be a low ionization zone of the disk wind.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Effect of micron-scale manufacturing flaws on the tensile response of centimeter sized two-photon polymerization microlattices

Two-photon polymerization (TPP) is a unique fabrication technique that enables sub-micron scale resolution. Herein, we report on uniaxial tensile tests on millimeter-sized TPP log-pile structures that were fabricated using a recently developed interdigitated stitching strategy. As expected, the Young’s modulus increased with laser intensity, however elastic modulus, ultimate strength and strain-at-failure varied widely, even for nominally identical samples. Post-mortem analysis revealed a series of print defects resulting from various sources including misalignments, resin shrinkage, laser beam shadowing, and local depletion of the oxygen inhibitor. While some of the defects can be eliminated, such as misalignments due to insufficient precision of the mechanical stage, others are more intrinsic to TPP and thus more difficult to address.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Proton Beam Therapy and Concurrent Chemotherapy for Esophageal Cancer

Purpose: Proton beam therapy (PBT) is a promising modality for the management of thoracic malignancies. We report our preliminary experience of treating esophageal cancer patients with concurrent chemotherapy (CChT) and PBT (CChT/PBT) at MD Anderson Cancer Center. Methods and Materials: This is an analysis of 62 esophageal cancer patients enrolled on a prospective study evaluating normal tissue toxicity from CChT/PBT from 2006 to 2010. Patients were treated with passive scattering PBT with two- or three-field beam arrangement using 180 to 250 MV protons. We used the Kaplan-Meier method to assess time-to-event outcomes and compared the distributions between groups using the log-rank test. Results: The median follow-up time was 20.1 months for survivors. The median age was 68 years (range, 38-86). Most patients were males (82%) who had adenocarcinomas (76%) and Stage II-III disease (84%). The median radiation dose was 50.4 Gy (RBE [relative biologic equivalence]) (range, 36-57.6). The most common grade 2 to 3 acute toxicities from CChT/PBT were esophagitis (46.8%), fatigue (43.6%), nausea (33.9%), anorexia (30.1%), and radiation dermatitis (16.1%). There were two cases of grade 2 and 3 radiation pneumonitis and two cases of grade 5 toxicities. A total of 29 patients (46.8%) received preoperative CChT/PBT, with one postoperative death. The pathologic complete response (pCR) rate for the surgical cohort was 28%, and the pCR and near CR rates (0%-1% residual cells) were 50%. While there were significantly fewer local-regional recurrences in the preoperative group (3/29) than in the definitive CChT/PBT group (16/33) (log-rank test, p = 0.005), there were no differences in distant metastatic (DM)-free interval or overall survival (OS) between the two groups. Conclusions: This is the first report of patients treated with PBT/CChT for esophageal cancer. Our data suggest that this modality is associated with a few severe toxicities, but the pathologic response and clinical outcomes are encouraging. Prospective comparison with more traditional approach is warranted.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2024

Summary and Annotated Bibliography of Measurement Error Corrections with Potential Application in Future Quesst Mission Community Noise Studies

This document is motivated by likely needs of the Quesst mission community response tests, which will culminate in data collection and estimation of dose-response regression relationships for consideration by domestic and international aviation regulators. Furthermore, basic research questions evaluating interactions between rates of community annoyance, dose levels, and indicators of the presence of rattle, vibration, and startle hinge on hypothesis testing in the context of regression models. For a variety of reasons, noise doses may be known only imprecisely and may not reflect the actual level experienced by responding subjects. These differences between true dose and estimated dose, be they systematic or random, constitute covariate measurement error. Available statistics literature speaks to the impacts of measurement error on regression models, both in terms of bias in estimated coefficients and predicted values, and in terms of the loss of statistical power for hypothesis testing. Given the particulars of a categorical annoyance response variable and a continuous noise dose predictor variable subject to measurement error during testing, the emphasis of this report is on findings and methods pertinent to generalized linear (and mixed) models likely to be employed during the Quesst mission community tests. We reach the following conclusions: 1. Of four reviewed methods, structural Bayesian measurement error models and simulation extrapolation (SIMEX) may be the most readily applicable to Quesst mission community noise study objectives. 2. If warranted, a linear measurement model can help model systematic sources of measurement error that the classical measurement error does not. 3. For its ready implementation and small additional input requirements, simulation extrapolation may be ideally suited for addressing secondary research questions involving interactions between annoyance, noise dose, and other factors through hypothesis testing. 4. For their flexibility and ability to propagate uncertainty, structural Bayesian hierarchical models have great appeal for mission purposes; some care may be needed in developing appropriate probability models describing actual noise exposure during testing. An annotated bibliography logs additional papers and resources that may be of value to analysts in other projects and disciplines.

Dose-Response Model↗
NASA NTRS1993

X-ray/microwave relation of different types of active stars

Coronal active stars of seven classes between spectral types F and M, single and double, are compared in their quiescent radio and X-ray luminosities L(R) and L(X). We find, largely independent of stellar class, log L(X) is less than about log L(R) + 15.5. This general relation points to an intimate connection between the nonthermal, energetic electrons causing the radio emission and the bulk plasma of the corona responsible for thermal X-rays. The relation, observed over six orders of magnitude, suggests that the heating mechanism necessarily involves particle acceleration. We derive requirements for simple models based on optically thin gyrosynchrotron emission of mildly relativistic electrons and thermal X-rays from the bulk plasma. We discuss the possibility that a portion of the accelerated particles heats the ambient plasma by collisions. More likely, plasma heating and particle acceleration may occur in parallel and in the same process, but at a fixed ratio.

Guedel, Manuel↗
NASA NTRS1995

The threshold for stellar winds in hot main-sequence stars

The profiles of ultraviolet resonance lines of C IV were surveyed in a sample of 29 cluster and association members in the spectral type range O9-B2 III-V, together with a few field stars of interest. The temperatures and gravities of the stars were taken from the model atmosphere analysis by Grigsby, Morrison, & Anderson (1992), and the luminosities were estimated on the basis of cluster and association distances from the recent literature. A parameter P(sub w) was defined in order to describe the degree and assymetry of the C IV profile. This parameter, together with total C IV equivalent width, was found to be well correlated with stellar luminosity and temperature. A few anomalous stars were noted: tau Sco, HD 66665, HD 13621, and the ON stars HD12323 and HD 201345. The results suggest a sudden onset of observable mass loss at T(effective) = 27,500 +/- 500 K, log (L/solar luminosity) = 4.4 +/- 0.12, in agreement with the previous study by Prinja (1989). At T(effective) = 28,000 K and log g = 4, our non-LTE model atmospheres show an enhancement in the ground-state population of C(+3) in their topmost layer, which could be responsible for initiation of the winds via radiation pressure on the C(+3) ions, or for the onset of visibility of C(+3) ions in the wind because of an increase in the optical depth in the C IV lines in the outermost layers.

Grigsby, James A.↗
DOE OSTI2013

Phosphor Thermometry Signal Analysis and Interpretation

Since the last International Temperature Symposium, phosphor thermometry has continued to mature with considerable attention given to combustion and turbine engine applications. More recently the utility to problems on the micro- and nano-scales has appreciated, particularly in regard to biological and biomedical situations. The method is therefore used for a wide range of situations. Signal interpretation is important and experience teaches that without sufficient care phosphor signals can be misleading. In order to advance the method, signal analysis investigations should prove fruitful. The specific aspect addressed here is the question of waveform sampling. A simple phenomenological approach is described that explores how the number of points digitized per waveform affects the measurement repeatability and accuracy. This is demonstrated for single shot signals and the average of 512 sequential waveforms. A bright temperature-independent luminescence signal from YVO4:Eu is sampled every 800 ps for a highly sampled condition and every 8 microseconds for a low sampled condition. When the average of 512 waveforms are compared for the two sampling conditions, they differ by only 0.4%. For the highly sampled case, a noisy single shot waveform compared to the averaged waveform differed by 1.8%. Future efforts on this subject will address intermediate and lower sampling rates. Also, variable window techniques should be explored that are especially important for non-log-linear signals. Investigations, such as this, give the developer the requisite information for designing analysis systems appropriate for the intended application in terms of precision, accuracy, and response time.

Fluorescence thermometry↗
DOE OSTI2016

Standardization of Geophysical Logging Data at the Hanford Site - 16208

Gamma activity has been measured in boreholes at the US DOE Hanford Site in southeastern Washington State since the 1940's. Over the years, detectors and data recording methods have changed, but the accumulated data provide a record of subsurface gamma activity spanning the period from active operations into interim stabilization. A basic problem is comparability of data between different detectors over a wide range of gamma activity. Many logs are simply presented in terms of raw count rate, and it is difficult to compare count rates between two different detectors, particularly when they have very different response characteristics. The Hanford Gamma Unit (HGU) is proposed as an empirical unit of gamma activity. The HGU is defined in terms of gamma activity at a specified location at the Hanford Borehole Model Facility, and its magnitude is defined such that 1 HGU is approximately equal to typical background gamma activity in uncontaminated soil. The HGU provides a means to convey information about the basic level of subsurface contamination without any implications as to the specific source of the gamma activity. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2003

MODIS NDVI Response Following Fires in Siberia

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

Ranson, K. Jon↗
DOE OSTI2023

Conditional Karhunen–Loève regression model with Basis Adaptation for high-dimensional problems: Uncertainty quantification and inverse modeling

Here, we propose a methodology for improving the accuracy of surrogate models of the observable response of physical systems as a function of the systems’ spatially heterogeneous parameter fields, with applications to uncertainty quantification and parameter estimation in high-dimensional problems. Practitioners often formulate finite-dimensional representations of spatially heterogeneous parameter fields using truncated unconditional Karhunen–Loève expansions (KLEs) for a certain choice of unconditional covariance kernel and construct surrogate models of the observable response with respect to the KLE coefficients. When direct measurements of the parameter fields are available, we propose improving the accuracy of these surrogate models by representing the parameter fields via conditional Karhunen-Loève expansions (CKLEs). CKLEs are constructed by conditioning the covariance kernel of the unconditional expansion on the direct measurements of the parameter field via Gaussian process regression, and then truncating the corresponding KLE. We apply the proposed methodology to constructing surrogate models via the Basis Adaptation (BA) method of the stationary hydraulic head response, measured at spatially discrete observation locations, of a groundwater flow model of the Hanford Site, as a function of the 1000-dimensional representation of the model’s log-transmissivity field. We find that BA surrogate models of the hydraulic head based on CKLEs are more accurate than BA surrogate models based on unconditional expansions for forward uncertainty quantification tasks. Furthermore, we find that inverse estimates of the hydraulic transmissivity field computed using CKLE-based BA surrogate models are more accurate than those computed using unconditional BA surrogate models.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS2014

CEO Sites Mission Management System (SMMS)

Late in fiscal year 2011, the Crew Earth Observations (CEO) team was tasked to upgrade its science site database management tool, which at the time was integrated with the Automated Mission Planning System (AMPS) originally developed for Earth Observations mission planning in the 1980s. Although AMPS had been adapted and was reliably used by CEO for International Space Station (ISS) payload operations support, the database structure was dated, and the compiler required for modifications would not be supported in the Windows 7 64-bit operating system scheduled for implementation the following year. The Sites Mission Management System (SMMS) is now the tool used by CEO to manage a heritage Structured Query Language (SQL) database of more than 2,000 records for Earth science sites. SMMS is a carefully designed and crafted in-house software package with complete and detailed help files available for the user and meticulous internal documentation for future modifications. It was delivered in February 2012 for test and evaluation. Following acceptance, it was implemented for CEO mission operations support in April 2012. The database spans the period from the earliest systematic requests for astronaut photography during the shuttle era to current ISS mission support of the CEO science payload. Besides logging basic image information (site names, locations, broad application categories, and mission requests), the upgraded database management tool now tracks dates of creation, modification, and activation; imagery acquired in response to requests; the status and location of ancillary site information; and affiliations with studies, their sponsors, and collaborators. SMMS was designed to facilitate overall mission planning in terms of site selection and activation and provide the necessary site parameters for the Satellite Tool Kit (STK) Integrated Message Production List Editor (SIMPLE), which is used by CEO operations to perform daily ISS mission planning. The CEO team uses the SMMS for three general functions - database queries of content and status, individual site creation and updates, and mission planning. The CEO administrator of the science site database is able to create or modify the content of sites and activate or deactivate them based on the requirements of the sponsors. The administrator supports and implements ISS mission planning by assembling, reporting, and activating mission-specific site selections for management; deactivating sites as requirements are met; and creating new sites, such as International Charter sites for disasters, as circumstances warrant. In addition to the above CEO internal uses, when site planning for a specific ISS mission is complete and approved, the SMMS can produce and export those essential site database elements for the mission into XML format for use by onboard Earth-location systems, such as Worldmap. The design, development, and implementation of the SMMS resulted in a superior database management system for CEO science sites by focusing on the functions and applications of the database alone instead of integrating the database with the multipurpose configuration of the AMPS. Unlike the AMPS, it can function and be modified within the existing Windows 7 environment. The functions and applications of the SMMS were expanded to accommodate more database elements, report products, and a streamlined interface for data entry and review. A particularly elegant enhancement in data entry was the integration of the Google Earth application for the visual display and definition of site coordinates for site areas defined by multiple coordinates. Transfer between the SMMS and Google Earth is accomplished with a Keyhole Markup Language (KML) expression of geographic data (see figures 3 and 4). Site coordinates may be entered into the SMMS panel directly for display in Google Earth, or the coordinates may be defined on the Google Earth display as a mouse-controlled polygonal definition and transferred back into the SMMS as KML input. This significantly reduces the possibility of errors in coordinate entries and provides visualization of the scale of the site being defined. CEO now has a powerful tool for managing and defining sites on the Earth's surface for both targets of astronaut photography or other onboard remote sensing systems. It can also record and track results by sponsor, collaborator, or type of study.

Trenchard, Mike↗
DOE OSTI2011

Change in the Growth Rate of Localized Pancreatic Adenocarcinoma in Response to Gemcitabine, Bevacizumab, and Radiation Therapy on MDCT

Purpose: To depict treatment response to chemoradiotherapy by comparing tumor growth rate between treated and untreated patients and to compare depicted response with objective response according to the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 guideline. Methods and Materials: This Health Insurance Portability and Accountability Act-compliant, retrospective study was approved by the institutional review board. Volume doubling time (DT) of histologically confirmed locally advanced pancreatic adenocarcinoma was calculated in 16 patients treated with chemoradiotherapy and 10 untreated patients by incorporating interscan interval ({Delta}t) and tumor volume at baseline (V0) and follow-up (V1) obtained by semiautomated segmentation into the following equation: DT = {Delta}t . log 2/log (V1/V0). Reciprocal of doubling time (RDT), which is the linear representation of tumor growth rate, was calculated by use of the following equation: RDT = 365/DT. The lowest RDT value of 2.42 in untreated patients was considered as the cutoff value for depiction of treatment response. Depicted response rate was defined as the proportion of patients with an RDT value of less than 2.42. Depicted response was compared with objective response according to the RECIST 1.1 guideline. The significance level was set at p < 0.05. Results: There was a significant difference in mean RDT between treated (range, -7.12 to 3.27; mean, -1.27; median, -1.30) and untreated (range, 2.42 to 10.74; mean, 5.33; median, 4.26) patients (p < 0.05). Reciprocal of doubling time was less than 2.42 in 14 treated patients, which corresponded to a depicted response rate of 87.50% as opposed to the objective response rate of 18.75% according to the RECIST 1.1 guideline (p < 0.05) and carbohydrate antigen 19-9 response rate of 62.50% (p > 0.05). Carbohydrate antigen 19-9 response was concordant with RDT and RECIST response in 12 patients (75.00%) ({kappa}, 0.38) and 9 patients (56.25%) ({kappa}, 0.24), respectively. Conclusions: There was a significant difference between depicted response according to RDT and objective response according to RECIST. Reciprocal of doubling time might serve as a valuable biomarker for evaluation of treatment response when depiction of small changes in tumor size is concerned.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Bidisperse and polydisperse suspension rheology at large solid fraction

At the same solid volume fraction, bidisperse and polydisperse suspensions display lower viscosities, and weaker normal stress response, compared to monodisperse suspensions. The reduction of viscosity associated with size distribution can be explained by an increase of the maximum flowable, or jamming, solid fraction. In this work, concentrated or "dense" suspensions are simulated under strong shearing, where thermal motion and repulsive forces are negligible, but we allow for particle contact with a mild frictional interaction with interparticle friction coefficient of 0.2. Aspects of bidisperse suspension rheology are first revisited to establish that the approach reproduces established trends; the study of bidisperse suspensions at size ratios of large to small particle radii (2 to 4) shows that a minimum in the viscosity occurs for zeta slightly above 0.5, where zeta=phi_{large}/phi is the fraction of the total solid volume occupied by the large particles. The simple shear flows of polydisperse suspensions with truncated normal and log normal size distributions, and bidisperse suspensions which are statistically equivalent with these polydisperse cases up to third moment of the size distribution, are simulated and the rheologies are extracted. Prior work shows that such distributions with equivalent low-order moments have similar phi_{m}, and the rheological behaviors of normal, log normal and bidisperse cases are shown to be in close agreement for a wide range of standard deviation in particle size, with standard correlations which are functionally dependent on phi/phi_{m} providing excellent agreement with the rheology found in simulation. The close agreement of both viscosity and normal stress response between bi- and polydisperse suspensions demonstrates the controlling in influence of the maximum packing fraction in noncolloidal suspensions. Microstructural investigations and the stress distribution according to particle size are also presented.

Pednekar, Sidhant↗