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Sample records for psp diffuse measurements

  1. Selective frontal neurodegeneration of the inferior fronto-occipital fasciculus in progressive supranuclear palsy (PSP demonstrated by diffusion tensor tractography

    Directory of Open Access Journals (Sweden)

    Elfgren Christina

    2011-01-01

    Full Text Available Abstract Background The clinical presentation in progressive supranuclear palsy (PSP, an atypical parkinsonian disorder, includes varying degrees of frontal dysexecutive symptoms. Using diffusion tensor imaging (DTI and tractography (DTT, we investigated whether diffusion changes and atrophy of the inferior fronto-occipital fasciculus (IFO occurs in PSP and if these changes correlate with disease stage and clinical phenotype. The corticospinal tract (CST, which is often involved in PSP, was investigated for comparison. Methods DTI of the whole brain was performed with a 3 T MR scanner using a single shot-EPI sequence with diffusion encoding in 48 directions. Scans were obtained in patients with PSP (n = 13 and healthy age-matched controls (n = 12. DTT of the IFO and CST was performed with the PRIDE fibre tracking tool (Philips Medical System. Fractional anisotropy (FA and apparent diffusion coefficient (ADC were calculated and correlated with disease stage and clinical phenotype. Results In patients with PSP, significantly decreased FA and increased ADC was found in the frontal part of IFO compared with the medial and occipital parts of IFO, as well as compared to controls. Four of the thirteen patients with PSP showed a marked decrease in the number of tracked voxels in the frontal part of IFO. These findings were most pronounced in patients with severe frontal cognitive symptoms, such as dysexecutive problems, apathy and personality change. There was a strong correlation (r2 = -0.84; p Conclusions DTT for identification of neuronal tracts with subsequent measurement of FA and ADC is a useful diagnostic tool for demonstrating patterns of neuronal tract involvement in neurodegenerative disease. In selected tracts, FA and ADC values might act as surrogate markers for disease stage.

  2. Simultaneous PSP and TSP measurements of transient flow in a long-duration hypersonic tunnel

    Science.gov (United States)

    Peng, Di; Jiao, Lingrui; Sun, Zhijun; Gu, Yunsong; Liu, Yingzheng

    2016-12-01

    The current work presents simultaneous measurements of transient flow using fast-responding pressure- and temperature-sensitive paints in a long-duration hypersonic tunnel; the pressure, temperature and heat flux fields were obtained on a standard model (HB-2) at Ma = 5. Fast PSP and TSP were applied symmetrically on the model with low thermal conductivity. Both coatings were illuminated by a UV-LED, and unsteady pressure and temperature data were recorded at 500 Hz using a high-speed camera. Time-dependent temperature correction was applied on the PSP data based on the TSP results, while the heat flux was calculated from the time-resolved temperature fields using a 1D semi-finite heat conduction model. The temperature-induced errors in PSP data were effectively removed by the current compensation method. The pressure and heat flux results showed good agreement with the reference data from previous studies. The key events throughout the hypersonic tunnel run were captured by the unsteady PSP/TSP data, including the tunnel start-up, the flow build-up, the steady flow period and the tunnel shutdown. The differences caused by the change of attack angle were also clearly recognized. The current PSP/TSP system has shown great potential for unsteady flow diagnostics in hypersonic flows.

  3. MEASUREMENTS OF PRESSURE DISTRIBUTIONS ON A ROTOR BLADE USING PSP TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Kidong Kim

    2011-12-01

    Full Text Available Surface pressure distributions on a rotating blade were measured by using pressure sensitive paint (PSP to understand aerodynamic characteristics of a rotor blade. The present study was conducted to investigate the PSP techniques for measuring the pressure distributions on a rotor blade. In order to perform the experiment, the PSP was required to response very fast due to rapid pressure fluctuations on a rotor blade. High energy excitation light source was also needed to acquire proper intensity images in a short excitation time. The techniques were based on a lifetime method. Qualitative pressure distributions on an upper surface of small scale rotor in hovering condition were measured as a preliminary experiment prior to forward flight conditions in the KARI low speed wind tunnel laboratory. From measured pressure distributions, striking pressure gradient was observed on an upper surface of rotor blade and the resulting pressure showed expected gradient depending on different collective pitch angles. ABSTRAK : Pengagihan tekanan permukaan ke atas berbilah putar disukat menggunakan cat sensitive tekanan (pressure sensitive paint (PSP untuk memahami sifat-sifat aerodinamik suatu berbilah putar. Kajian telah dijalankan untuk menyelidik teknik-teknik PSP dengan mengukur agihan tekanan ke atas suatu berbilah putar. Agar eksperimen dapat dijalankan dengan baik, PSP harus bertindak cepat kerana tekanan naik turun dengan pantas ke atas berbilah putar. Sumber cahaya ujaan tenaga tinggi diperlukan untuk mendapatkan imej keamatan wajar dalam jangka masa ujaan yang pendek. Teknik-teknik tersebut terhasil daripada kajian semasa hayat. Agihan tekanan kualitatif ke permukaan atas berskala kecil pemutar dalam keadaan mengapung diukur sebagai permulaan eksperimen, sebelum penerbangan kehadapan dalam makmal terowong angin laju rendah KARI. Daripada agihan tekanan yang disukat, kecerunan tekanan yang ketara diperolehi daripada permerhatian terhadap permukaan

  4. Advanced lifetime PSP imaging system for pressure and temperature field measurement

    Science.gov (United States)

    Mitsuo, Kazunori; Asai, Keisuke; Takahashi, Akira; Mizushima, Hiroshi

    2006-06-01

    The newly designed lifetime imaging system (LIS), which was composed of a multi-gated CCD camera and LED illuminators, has been developed to measure simultaneously pressure and temperature field from luminescent lifetime decay of pressure-sensitive paint (PSP). The new system could reduce the measurement error due to shot noise of a CCD and laser speckle, compared to the previous lifetime imaging system. Optimization of PSP film thickness on white basecoat was also conducted for improving measurement accuracy, and could minimize the measurement error. As a verification test, pressure and temperature images on a simple delta wing were visualized by the newly designed LIS. The quality of the pressure image was considerably improved in comparison with that measured by the previous system. These results indicated that the new LIS was a practical measurement tool to acquire simultaneously pressure and temperature field on an aerodynamic model surface.

  5. Single-shot lifetime-based PSP and TSP measurements on turbocharger compressor blades

    Science.gov (United States)

    Peng, Di; Jiao, Lingrui; Yu, Yuelong; Liu, Yingzheng; Oshio, Tetsuya; Kawakubo, Tomoki; Yakushiji, Akimitsu

    2017-09-01

    Fast-responding pressure-sensitive paint (Fast PSP) and temperature-sensitive paint (TSP) measurements were conducted on two turbocharger compressors using a single-shot lifetime-based technique. The fast PSP and TSP were applied on separate blades of one compressor, and both paints were excited by a pulsed 532 nm Nd:YAG laser. The luminescent decay signals following the laser pulse were recorded by a CCD camera in a double-exposure mode. Instantaneous pressure and temperature fields on compressor blades were obtained simultaneously, for rotation speeds up to 150,000 rpm. The variations in pressure and temperature fields with rotation speed, flow rate and runtime were clearly visualized, showing the advantage of high spatial resolution. Severe image blurring problems and significant temperature-induced errors in the PSP results were found at high rotation speeds. The first issue was addressed by incorporating a deconvolution-based deblurring algorithm to recover the clear image from the blurred image using the combination of luminescent lifetime and rotation speed. The second issue was resolved by applying a pixel-by-pixel temperature correction based on the TSP results. The current technique has shown great capabilities in flow diagnostics of turbomachinery and can serve as a powerful tool for CFD validations and design optimizations.

  6. Apparent diffusion coefficient measurements in progressive supranuclear palsy

    Energy Technology Data Exchange (ETDEWEB)

    Ohshita, T.; Oka, M.; Imon, Y.; Yamaguchi, S.; Mimori, Y.; Nakamura, S. [Hiroshima Univ. (Japan). School of Medicine

    2000-09-01

    We measured the apparent diffusion coefficient (ADC), using diffusion-weighted imaging (DWI) and signal intensity on T2-weighted MRI in the cerebral white matter of patients with progressive supranuclear palsy (PSP) and age-matched normal subjects. In PSP, ADC in the prefrontal and precentral white matter was significantly higher than in controls. There was no significant difference in signal intensity on T2-weighted images. The ADC did correlate with signal intensity. The distribution of the elevation of ADC may be the consequence of underlying pathological changes, such as neurofibrillary tangles or glial fibrillary tangles in the cortex. Our findings suggest that ADC measurement might be useful for demonstrating subtle neuropathological changes. (orig.)

  7. Self-Reported Graphic Personal and Social Performance Scale (SRG-PSP) for measuring functionality in patients with bipolar disorder.

    Science.gov (United States)

    Mei Bai, Ya; Li, Cheng-Ta; Chen, Mu-Hong; Kuang Yang, Yen

    2017-06-01

    The self-reported graphic version of the Personal and Social Performance Scale (SRG-PSP) is the first graphic, self-reported rating scale that assesses functioning, and its reliability and validity have been documented in patients with schizophrenia. This study investigated the validity of SRG-PSP in patients with bipolar disorder (BD). Patients with BD were recruited from psychiatric outpatient clinics, and assessed with the Young Mania Rating Scale (YMRS), the Montgomery-Åsberg Depression Rating Scale (MADRS), the Clinical Global Impression Scale (CGI)-Bipolar and CGI-Depression, the Positive and Negative Symptom Scale (PANSS), the Global assessment of function (GAF), and the PSP. All participants completed the self-rating questionnaires: the SRG-PSP, the 36-Item Short-Form Health Survey (SF-36), and the Sheehan disability Scale (SDS). In total, 114 patients with BD were enrolled. The criterion-related validities between the SRG-PSP and the PSP were all significantly correlated with their counterparts. The global score of the SRG-PSP was significantly correlated with the scores of the YMRS, MADRS, PANSS, CGI-Depression, GAF, SF-36, and SDS. Three SRG-PSP domains (socially useful activities, personal and social relationships, and self-care) were negatively correlated with the scores of the MADRS, PANSS, CGI-depression, and SDS; and were positively correlated with the GAF, SF-36 scores. The disturbing and aggressive behavior domain was positively correlated with the scores of the YMRS, MADRS, PANSS, CGI-Bipolar, CGI-Depression, and SDS; and was negatively correlated with the GAF, SF-36 scores (all p<0.01). The SRG-PSP is a validated self-reported scale for assessing functionality in patients with BD. Copyright © 2017. Published by Elsevier B.V.

  8. Development of Two-Photon Pump Polarization Spectroscopy Probe Technique Tpp-Psp for Measurements of Atomic Hydrogen .

    Science.gov (United States)

    Satija, Aman; Lucht, Robert P.

    2015-06-01

    Atomic hydrogen (H) is a key radical in combustion and plasmas. Accurate knowledge of its concentration can be used to better understand transient phenomenon such as ignition and extinction in combustion environments. Laser induced polarization spectroscopy is a spatially resolved absorption technique which we have adapted for quantitative measurements of H atom. This adaptation is called two-photon pump, polarization spectroscopy probe technique (TPP-PSP) and it has been implemented using two different laser excitation schemes. The first scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-3P levels using a circularly polarized 656-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 656 nm. As a result, the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. The laser beams were created by optical parametric generation followed by multiple pulse dye amplification stages. This resulted in narrow linewidth beams which could be scanned in frequency domain and varied in energy. This allowed us to systematically investigate saturation and Stark effect in 2S-3P transitions with the goal of developing a quantitative H atom measurement technique. The second scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-4P transitions using a circularly polarized 486-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 486 nm. As a result the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. A dye laser was pumped by third harmonic of a Nd:YAG laser to create a laser beam

  9. Simultaneous visualization of transonic buffet on a rocket faring model using unsteady PSP measurement and Schlieren method

    Science.gov (United States)

    Nakakita, K.

    2017-02-01

    Simultaneous visualization technique of the combination of the unsteady Pressure-Sensitive Paint and the Schlieren measurement was introduced. It was applied to a wind tunnel test of a rocket faring model at the JAXA 2mx2m transonic wind tunnel. Quantitative unsteady pressure field was acquired by the unsteady PSP measurement, which consisted of a high-speed camera, high-power laser diode, and so on. Qualitative flow structure was acquired by the Schlieren measurement using a high-speed camera and Xenon lamp with a blue optical filter. Simultaneous visualization was achieved 1.6 kfps frame rate and it gave the detailed structure of unsteady flow fields caused by the unsteady shock wave oscillation due to shock-wave/boundary-layer interaction around the juncture between cone and cylinder on the model. Simultaneous measurement results were merged into a movie including surface pressure distribution on the rocket faring and spatial structure of shock wave system concerning to transonic buffet. Constructed movie gave a timeseries and global information of transonic buffet flow field on the rocket faring model visually.

  10. Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Younkin, K; Long, CN

    2003-11-01

    Simple single black detector pyranometers, such as the Eppley Precision Spectral Pyranometer (PSP) used by the Atmospheric Radiation Measurement (ARM) Program, are known to lose energy via infrared (IR) emission to the sky. This is especially a problem when making clear-sky diffuse shortwave (SW) measurements, which are inherently of low magnitude and suffer the greatest IR loss. Dutton et al. (2001) proposed a technique using information from collocated pyrgeometers to help compensate for this IR loss. The technique uses an empirically derived relationship between the pyrgeometer detector data (and alternatively the detector data plus the difference between the pyrgeometer case and dome temperatures) and the nighttime pyranometer IR loss data. This relationship is then used to apply a correction to the diffuse SW data during daylight hours. We developed an ARM value-added product (VAP) called the SW DIFF CORR 1DUTT VAP to apply the Dutton et al. correction technique to ARM PSP diffuse SW measurements.

  11. Diffusion measurements by Raman spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Shapiro, Alexander; Berg, Rolf W.

    Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt......Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt...

  12. Anisotropy in "isotropic diffusion" measurements due to nongaussian diffusion

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Olesen, Jonas Lynge; Ianuş, Andrada

    2017-01-01

    model-free decomposition of diffusion signal kurtosis into terms originating from either ensemble variance of isotropic diffusivity or microscopic diffusion anisotropy. This ability rests on the assumption that diffusion can be described as a sum of multiple Gaussian compartments, but this is often...... dependence of the diffusion tensors, which causes the measured isotropic diffusivity to depend on gradient frame orientation. In turn, this conflates orientation dispersion with ensemble variance in isotropic diffusivity. Second, additional contributions to the apparent variance in isotropic diffusivity...

  13. Kurtosis as a diffuseness measure

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    This study presents a kurtosis analysis of room impulse responses as a potential room diffuseness measure. In the early part of an impulse response, sound pressure samples do not constitute a Gaussian distribution due to the direct sound and strong reflections. Such deterministic reflections...... are extreme events, which prevent the pressure samples from being normally distributed, leading to a high kurtosis. As the reflections are sparser and stronger, the sound field becomes less diffuse and the kurtosis systematically increases, indicating that it can be used as a diffuseness measure. The kurtosis...... converges to zero, as the reflection overlap becomes heavier, which is an important condition for a perfect diffuse field. Two rooms are analyzed. A small rectangular room shows that a non-uniform surface absorption distribution tends to increase the kurtosis significantly. A full scale reverberation...

  14. Effects of PspA and antibodies to PspA on activation and deposition of complement on the pneumococcal surface.

    Science.gov (United States)

    Ren, Bing; Szalai, Alexander J; Hollingshead, Susan K; Briles, David E

    2004-01-01

    Streptococcus pneumoniae infection is a frequent cause of pneumonia, otitis media, meningitis, and septicemia. Pneumococcal surface protein A (PspA) is an important virulence factor on the pathogen surface, and it is known to interfere with complement activation. In this study, flow cytometry was used to study the effects of PspA and antibodies to PspA on the deposition of complement C3 on the surface of a capsular type 3 strain, WU2, and its PspA- mutant, JY1119. Using naive mouse serum as a complement source, measurable deposition of C3 was observed within 4 min on PspA- pneumococci, and the amount of surface-bound C3 accumulated rapidly as the amount of serum was increased. In contrast, very little C3 was deposited on the PspA+ strain. In nonimmune mouse serum, the classical pathway was the dominant activation pathway triggered by PspA- pneumococci. Accordingly, EGTA blocked almost all of the complement activation. Moreover, a significant amount of C3 was still deposited on the PspA- strain when serum from factor B-deficient mice was used. This deposition was not observed on the PspA+ pneumococci, indicating that PspA may inhibit complement deposition via the classical pathway. Furthermore, under the conditions we tested, PspA also inhibited C3 deposition when the classical pathway was initiated by antibodies to capsular polysaccharide. Antibodies to PspA could overcome the anticomplementary effect of PspA, allowing for increased complement activation and C3 deposition onto PspA+ bacteria.

  15. PSP Program close out documentation

    Energy Technology Data Exchange (ETDEWEB)

    Andringa, K.; Hootman, H.E.; Ferrara, A.S.; Smith, P.K.; Congdon, J.W.; Randolph, H.W.; Young, R.H.; Driggers, F.E.; Topp, S.V.

    1985-12-31

    In December 1982 DOE-SR directed SRL to study the feasibility and impact of a program to lower the U-236 content of the Highly Enriched Uranium (HEU) stockpile used as fuel for the SRP reactors. In response to this request SRL assessed four technologies, Atomic Vapor Laser Isotope Separation (AVLIS), Molecular Laser Isotope Separation (MLIS), Gas Centrifuge, and the Plasma Separation Process (PSP) for this purpose with the assistance of the Engineering Department. In April 1983 cost/benefit analyses for these processes, high spot cost estimates for production facilities, and process uncertainties were submitted to DOE-SR with a recommendation to proceed with the conceptual design and supporting development programs for a facility based on the use of the PSP process. The current program status for the PSP development program at SRL and the design and documentation of a production facility at SRP, referred to as the Fuel Improvement Demonstration Facility (FIDF), is described in this report.

  16. Progressive Supranuclear Palsy (PSP): Frequently Asked Questions

    Science.gov (United States)

    ... PSP in some cases. Sinemet. This is the brand name for a combination of “levodopa” and “carbidopa.” ... A major goal of CurePSP is to increase awareness of PSP, CBD, MSA and related brain diseases ...

  17. MRI gray and white matter measures in progressive supranuclear palsy and corticobasal syndrome.

    Science.gov (United States)

    Upadhyay, Neeraj; Suppa, Antonio; Piattella, Maria Cristina; Bologna, Matteo; Di Stasio, Flavio; Formica, Alessandra; Tona, Francesca; Colosimo, Carlo; Berardelli, Alfredo; Pantano, Patrizia

    2016-10-01

    We evaluated MRI measures of gray and white matter damages in 19 patients with progressive supranuclear palsy (PSP), 11 with corticobasal syndrome (CBS), and 14 healthy subjects (HS) to differentiate patients with PSP from those with CBS. We calculated surface-based maps of the cortical volume, cortical thickness, surface area, and voxel level maps of sub-cortical volume, and diffusion tensor imaging parameters using automated scripts implemented in FreeSurfer and FSL toolboxes. No significant differences in cortical volume loss were observed between PSP and CBS. When cortical volume was divided into cortical thickness and surface area, cortical thickness in peri-rolandic brain regions was significantly smaller in CBS than in PSP patients, whereas surface area was significantly smaller in PSP than HS. We also found widespread volume loss in sub-cortical structures in patients with PSP and CBS in comparison to HS. Both patient groups displayed diffusion tensor imaging abnormalities: compared to HS, widespread fractional anisotropy and radial diffusivity changes were observed in PSP, whereas axial and radial diffusivity changes were prominent in CBS. Mini-mental state examination positively correlated with diffusion changes in patients with PSP. In conclusion, cortical thickness, surface area, and diffusion tensor imaging parameters may be sensitive enough to help differentiate patients with PSP from those with CBS.

  18. Diffusions conditioned on occupation measures

    Science.gov (United States)

    Angeletti, Florian; Touchette, Hugo

    2016-02-01

    A Markov process fluctuating away from its typical behavior can be represented in the long-time limit by another Markov process, called the effective or driven process, having the same stationary states as the original process conditioned on the fluctuation observed. We construct here this driven process for diffusions spending an atypical fraction of their evolution in some region of state space, corresponding mathematically to stochastic differential equations conditioned on occupation measures. As an illustration, we consider the Langevin equation conditioned on staying for a fraction of time in different intervals of the real line, including the positive half-line which leads to a generalization of the Brownian meander problem. Other applications related to quasi-stationary distributions, metastable states, noisy chemical reactions, queues, and random walks are discussed.

  19. Simultaneous measurements of thermal conductivity and diffusivity ...

    Indian Academy of Sciences (India)

    Abstract. Measurements of thermal conductivity and thermal diffusivity of twin pellets of Se80Te20–xInx. (x = 2, 4, 6 and 10) glasses, prepared under a load of 5 tons were carried out at room temperature using transient plane source (TPS) technique. The measured values of both thermal conductivity and diffusivity were used ...

  20. Resection methodology for PSP data processing: Recent ...

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    Experimental Aerodynamics Division, National Aerospace Laboratories,. P B No 1779, Airport Road, Bangalore e-mail: {craju,venkat}@ead.cmmacs.ernet.in. Abstract. PSP data processing, which primarily involves image alignment and image analysis, is a crucial element in obtaining accurate PSP results. There are two.

  1. Wanted: Scalable Tracers for Diffusion Measurements

    Science.gov (United States)

    2015-01-01

    Scalable tracers are potentially a useful tool to examine diffusion mechanisms and to predict diffusion coefficients, particularly for hindered diffusion in complex, heterogeneous, or crowded systems. Scalable tracers are defined as a series of tracers varying in size but with the same shape, structure, surface chemistry, deformability, and diffusion mechanism. Both chemical homology and constant dynamics are required. In particular, branching must not vary with size, and there must be no transition between ordinary diffusion and reptation. Measurements using scalable tracers yield the mean diffusion coefficient as a function of size alone; measurements using nonscalable tracers yield the variation due to differences in the other properties. Candidate scalable tracers are discussed for two-dimensional (2D) diffusion in membranes and three-dimensional diffusion in aqueous solutions. Correlations to predict the mean diffusion coefficient of globular biomolecules from molecular mass are reviewed briefly. Specific suggestions for the 3D case include the use of synthetic dendrimers or random hyperbranched polymers instead of dextran and the use of core–shell quantum dots. Another useful tool would be a series of scalable tracers varying in deformability alone, prepared by varying the density of crosslinking in a polymer to make say “reinforced Ficoll” or “reinforced hyperbranched polyglycerol.” PMID:25319586

  2. Conceptual design for PSP mounting bracket

    Energy Technology Data Exchange (ETDEWEB)

    Ransom, G.; Stein, R. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    Protective structural packages (PSP`s or overpacks) used to ship 2 1/2-ton UF{sub 6} product cylinders are bolted to truck trailers. All bolts penetrate two longitudinal rows of wooden planks. Removal and replacement is required at various intervals for maintenance and routine testing. A conceptual design is presented for mounting brackets which would securely attach PSP`s to trailer frames, reduce removal and replacement time, and minimize risk of personnel injury.

  3. Measuring nanoparticle diffusion in an ABELtrap

    Science.gov (United States)

    Dienerowitz, M.; Dienerowitz, F.; Börsch, M.

    2018-03-01

    Monitoring the Brownian motion of individual nanoscopic objects is key to investigate their transport properties and interactions with their close environment. Most techniques rely on transient diffusion through a detection volume or immobilisation, which restrict observation times or motility. We measure the diffusion coefficient and surface charge of individual nanoparticles and DNA molecules in an anti-Brownian electrokinetic trap (ABELtrap). This instrument is an active feedback trap confining the Brownian motion of a nanoparticle to the detection site by applying an electric field based on the particle’s current position. We simulate the Brownian motion of nanospheres in our sample geometry, including wall effects, due to partial confinement in the third dimension. The theoretically predicted values are in excellent agreement with our diffusion measurements in the ABELtrap. We also demonstrate the ABELtrap’s ability to measure varying sizes of DNA origami structures during denaturation.

  4. Local measurement of thermal conductivity and diffusivity

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, David H.; Schley, Robert S. [Materials Science and Engineering Department, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415-2209 (United States); Khafizov, Marat [Mechanical and Aerospace Engineering Department, The Ohio State University, 201 W. 19th Ave., Columbus, Ohio 43210 (United States); Wendt, Brycen L. [Nuclear Science and Engineering, Idaho State University, 921 S. 8th Ave., Pocatello, Idaho 83209-8060 (United States)

    2015-12-15

    Simultaneous measurement of local thermal diffusivity and conductivity is demonstrated on a range of ceramic samples. This was accomplished by measuring the temperature field spatial profile of samples excited by an amplitude modulated continuous wave laser beam. A thin gold film is applied to the samples to ensure strong optical absorption and to establish a second boundary condition that introduces an expression containing the substrate thermal conductivity. The diffusivity and conductivity are obtained by comparing the measured phase profile of the temperature field to a continuum based model. A sensitivity analysis is used to identify the optimal film thickness for extracting the both substrate conductivity and diffusivity. Proof of principle studies were conducted on a range of samples having thermal properties that are representatives of current and advanced accident tolerant nuclear fuels. It is shown that by including the Kapitza resistance as an additional fitting parameter, the measured conductivity and diffusivity of all the samples considered agreed closely with the literature values. A distinguishing feature of this technique is that it does not require a priori knowledge of the optical spot size which greatly increases measurement reliability and reproducibility.

  5. Simultaneous measurements of thermal conductivity and diffusivity ...

    Indian Academy of Sciences (India)

    80Te20–In ( = 2, 4, 6 and 10) glasses, prepared under a load of 5 tons were carried out at room temperature using transient plane source (TPS) technique. The measured values of both thermal conductivity and diffusivity were used to ...

  6. Detailed measurement on a HESCO diffuser

    DEFF Research Database (Denmark)

    Jensen, Rasmus Lund; Holm, Dorte; Nielsen, Peter V.

    2007-01-01

    This paper focuses on measuring the inlet velocity from a HESCO diffuser used in the IEA Annex 20 work as a function of the volume flow it provides. The aim of the present work is to establish a relation between the inlet velocity, the effective area and the airflow. This is important because the...

  7. Diffusion tensor analysis of corpus callosum in progressive supranuclear palsy

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Shoichi; Makino, Takahiro; Shirai, Wakako; Hattori, Takamichi [Department of Neurology, Graduate School of Medicine, Chiba University (Japan)

    2008-11-15

    Progressive supranuclear palsy (PSP) is a neurodegenerative disease featuring parkinsonism, supranuclear ophthalmoplegia, dysphagia, and frontal lobe dysfunction. The corpus callosum which consists of many commissure fibers probably reflects cerebral cortical function. Several previous reports showed atrophy or diffusion abnormalities of anterior corpus callosum in PSP patients, but partitioning method used in these studies was based on data obtained in nonhuman primates. In this study, we performed a diffusion tensor analysis using a new partitioning method for the human corpus callosum. Seven consecutive patients with PSP were compared with 29 age-matched patients with Parkinson's Disease (PD) and 19 age-matched healthy control subjects. All subjects underwent diffusion tensor magnetic resonance imaging, and the corpus callosum was partitioned into five areas on the mid-sagittal plane according to a recently established topography of human corpus callosum (CC1-prefrontal area, CC2-premotor and supplementary motor area, CC3-motor area, CC4-sensory area, CC5-parietal, temporal, and occipital area). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in each area and differences between groups were analyzed. In the PSP group, FA values were significantly decreased in CC1 and CC2, and ADC values were significantly increased in CC1 and CC2. Receiver operating characteristic analysis showed excellent reliability of FA and ADC analyses of CC1 for differentiating PSP from PD. The anterior corpus callosum corresponding to the prefrontal, premotor, and supplementary motor cortices is affected in PSP patients. This analysis can be an additional test for further confirmation of the diagnosis of PSP.

  8. 76 FR 5729 - Department of Defense Personnel Security Program (PSP)

    Science.gov (United States)

    2011-02-02

    ... of the Secretary 32 CFR Part 156 Department of Defense Personnel Security Program (PSP) AGENCY... for the Department of Defense (DoD) Personnel Security Program (PSP) in accordance with the provisions... Department of Defense Directive (DoDD) 5200.2, Personnel Security Program (PSP), codified at 32 CFR 156, was...

  9. Diffuse light correction for field reflectance measurements

    Science.gov (United States)

    Lamarr, John Henry

    The Remote Sensing Group of the Optical Sciences Center at the University of Arizona performs absolute radiometric calibration of Earth-viewing sensors using vicarious methods. The reflectance and irradiance-based methods require the nadir-view reflectance of a calibration site at sensor overpass. Errors in these reflectance data contribute directly to errors in the retrieved at sensor radiance, and therefore errors in the calibration. This research addresses two areas of improvement for the reflectance retrieval. The discreet laboratory data of the reference panel is spectrally interpolated using the measured hemispherical reflectance rather than a polynomial fit. This interpolation better fits an absorption feature of the reference material near 2200 nm. The desired reflectance is due to the directly- transmitted solar irradiance, but field measurements also include irradiance due to diffuse light. Non-lambertian properties of the reference and surface cause the ratio of the reflected total radiances to differ from the ratio of the reflected solar radiances. This difference can be corrected using additional field measurements, shaded surface/shaded-reference, output from a radiative transfer code, RTC-only, or a combination of both, shaded-reference. For the shaded-reference and RTC-only methods the shape of the bi-directional reflectance factor of the surface must be known to better than 10% to maintain a 2% accuracy for the retrievals, while the shaded-surface/shaded-reference method does not use the surface BRF. All three methods were applied to measurements of calibrated reflectance tarpaulins, and to measurements made at White Sands Missile Range. These data demonstrate that the shaded-surface/shaded-reference and RTC-only methods improve the surface reflectance retrieval, while the shaded-reference method is too sensitive to variations between the actual and modeled diffuse sky irradiance to be useful. This research represents significant improvements in

  10. The Disturbance of Gaze in Progressive Supranuclear Palsy (PSP: Implications for Pathogenesis

    Directory of Open Access Journals (Sweden)

    Athena L Chen

    2010-12-01

    Full Text Available Progressive supranuclear palsy (PSP is a disease of later life that is currently regarded as a form of neurodegenerative tauopathy. Disturbance of gaze is a cardinal clinical feature of PSP that often helps clinicians to establish the diagnosis. Since the neurobiology of gaze control is now well understood, it is possible to use eye movements as investigational tools to understand aspects of the pathogenesis of PSP. In this review, we summarize each disorder of gaze control that occurs in PSP, drawing on our studies of fifty patients, and on reports from other laboratories that have measured the disturbances of eye movements. When these gaze disorders are approached by considering each functional class of eye movements and its neurobiological basis, a distinct pattern of eye movement deficits emerges that provides insight into the pathogenesis of PSP. Although some aspects of all forms of eye movements are affected in PSP, the predominant defects concern vertical saccades (slow and hypometric, both up and down, impaired vergence, and inability to modulate the linear vestibulo-ocular reflex appropriately for viewing distance. These vertical and vergence eye movements habitually work in concert to enable visuomotor skills that are important during locomotion with the hands free. Taken with the prominent early feature of falls, these findings suggest that PSP tauopathy impairs a recently-evolved neural system concerned with bipedal locomotion in an erect posture and frequent gaze shifts between the distant environment and proximate hands. This approach provides a conceptual framework that can be used to address the nosological challenge posed by overlapping clinical and neuropathological features of neurodegenerative tauopathies.

  11. Operational Monitoring of Mines by COSMO-SkyMed PSP SAR Interferometry

    Science.gov (United States)

    Costantini, Mario; Malvarosa, Fabio; Miniati, Federico; de Assis, Luciano Mozer

    2016-08-01

    Synthetic aperture radar (SAR) interferometry is a powerful technology for detection and monitoring of slow ground surface movements. Monitoring of ground deformations in mining structures is an important application, particularly difficult because the scene changes with time. The persistent scatterer pair (PSP) approach, recently proposed to overcome some limitations of standard persistent scatter interferometry, proved to be effective also for mine monitoring. In this work, after resuming the main ideas of the PSP method, we describe the PSP measurements obtained from high- resolution X-band COSMO-SkyMed data over a large mining area in Minas Gerais state, Brazil. The outcomes demonstrate that dense and accurate ground deformation measurements can be obtained on the mining area and its structures (such as open pits, waste dumps, conveyor belts, water and tailings dams, etc.), achieving a consistent global view including also areas where field instruments are not installed.

  12. Principles and limitations of NMR diffusion measurements

    Directory of Open Access Journals (Sweden)

    Hrabe Jan

    2007-01-01

    Full Text Available Diffusion spectroscopy, imaging and particularly diffusion tensor imaging have become popular thanks to their numerous clinical and research applications which span from brain stroke evaluation to fiber tracking. With a few exceptions, these methods are rooted in the classic Stejskal-Tanner formula for the diffusion-attenuated signal, usually obtained by solving the Bloch-Torrey partial differential equations. Here we derive the Stejskal-Tanner formula in the simplest possible manner, avoiding integrals and differential equations. This approach makes it easy to understand the origin of the diffusion signal attenuation, the effects of various diffusion sequence parameters, and also the numerous important pitfalls, which are discussed in the last section.

  13. Metallic diffusion measured by a modified Knudsen technique

    Science.gov (United States)

    Fray, D. J.

    1969-01-01

    Diffusion coefficient of a metal in high temperature system is determined. From the measurement of the weight loss from a Knudsen cell, the vapor pressure of the escaping species can be calculated. If the only way this species can enter the Knudsen cell is by diffusion through a foil, the weight loss is diffusion flux.

  14. Measurements for Cu and Si diffusivities in Al-Cu-Si alloys by diffusion couples

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Dingfei [College of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China)]. E-mail: zhangdingfei@cqu.edu.cn; Morral, John E. [Department of Materials Science and Engineering, Ohio State University, OH 43210 (United States); Brody, Harold D. [Institute of Materials Science, University of Connecticut, CT 06268 (United States)

    2007-02-25

    This paper deals with diffusivity measurements for Cu and Si atoms in Al-Cu-Si alloys by diffusion couples. With Cu and Si concentration profiles in the diffusion couples treated by different heating temperatures and times, their diffusivities including D {sub CuCu}, D {sub SiSi}, D {sub CuSi} and D {sub SiCu} in Al-Cu-Si ternary alloys could be calculated and their D {sub 0} and Q also could be obtained by their diffusivities under different temperatures.

  15. Resolving and measuring diffusion in complex interfaces: Exploring new capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd M. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    This exploratory LDRD targeted the use of a new high resolution spectroscopic diffusion capabilities developed at Sandia to resolve transport processes at interfaces in heterogeneous polymer materials. In particular, the combination of high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy with pulsed field gradient (PFG) diffusion experiments were used to directly explore interface diffusion within heterogeneous polymer composites, including measuring diffusion for individual chemical species in multi-component mixtures. Several different types of heterogeneous polymer systems were studied using these HRMAS NMR diffusion capabilities to probe the resolution limitations, determine the spatial length scales involved, and explore the general applicability to specific heterogeneous systems. The investigations pursued included a) the direct measurement of the diffusion for poly(dimethyl siloxane) polymer (PDMS) on nano-porous materials, b) measurement of penetrant diffusion in additive manufactures (3D printed) processed PDMS composites, and c) the measurement of diffusion in swollen polymers/penetrant mixtures within nano-confined aluminum oxide membranes. The NMR diffusion results obtained were encouraging and allowed for an improved understanding of diffusion and transport processes at the molecular level, while at the same time demonstrating that the spatial heterogeneity that can be resolved using HRMAS NMR PFG diffusion experiment must be larger than ~μm length scales, expect for polymer transport within nanoporous carbons where additional chemical resolution improves the resolvable heterogeneous length scale to hundreds of nm.

  16. MEASUREMENT OF DIFFUSION COEFFICIENTS OF GAS MOLECULES IN ICE

    OpenAIRE

    サトウ, コウイチ; ウチダ, ツトム; ホンドウ, タケオ; マエ, シンジ; Kouichi, SATOH; Tsutomu, UCHIDA; Takeo, HONDOH; Shinji, MAE

    1994-01-01

    Measurements of diffusion coefficients of He gas and N_2 gas in ice crystals were carried out under the high pressure and atmosphere pressure. The understanding of diffusion phenomena of air molecules in ice is important on studying palaeo-environments by polar ice core analysis. But the measurements of gas molecules diffusion in ice have been done only for He and Ne. Thus we developed an apparatus to measure the diffusion coefficient of gas molecules in ice. In order to estimate the accuracy...

  17. Test-retest reliability of diffusion measures in cerebral white matter: A multiband diffusion MRI study.

    Science.gov (United States)

    Duan, Fei; Zhao, Tengda; He, Yong; Shu, Ni

    2015-10-01

    To investigate the test-retest (TRT) reliability of the diffusion measures in cerebral white matter obtained from the diffusion MRI dataset acquired with multiband acceleration. With the multiband diffusion MRI dataset with two repeated scanning sessions, the TRT reliability of diffusion measures (fractional anisotropy [FA], mean diffusivity [MD], primary diffusivity [PD] and transverse diffusivity [TD]) was investigated through several fully automated analysis methods, including two voxel-level analyses (voxel-based analysis [VBA] and tract-based spatial statistics [TBSS]) and an atlas ROI-based analysis. The reproducibility was assessed by the intra-class correlation coefficient (ICC). Our results demonstrated moderate to high reproducibility (ICC > 0.4) of diffusion measures from the multiband EPI sequence with different analysis approaches. Across different measures, FA exhibited the highest reproducibility (mean ICC = 0.70), while MD showed the lowest reliability (mean ICC = 0.55) (P = 0.006). Additionally, ICCs varied across different tract ROIs: Commissural tracts showed higher reproducibility than other categories of tracts (projection, association and brainstem), while the brainstem tracts exhibited the poorest reliability (P = 0.004). Our findings suggest a potential utility of the multiband EPI sequence for exploring individual differences of cerebral white matter and provide reference for future white matter studies. © 2015 Wiley Periodicals, Inc.

  18. DIFFUSION MEASUREMENTS DURING PERVAPORATION THROUGH A ZEOLITE MEMBRANE

    Science.gov (United States)

    An isotopic-transient technique was used to directly measure diffusion times of H2O, methanol, ethanol, 2-propanol, and acetone in pure and binary mixture feeds transporting through a zeolite membrane under steady-state pervaporation conditions. Diffusivities can be determ...

  19. Methods for measuring diffusion coefficients of radon in building materials

    NARCIS (Netherlands)

    Cozmuta, [No Value; van der Graaf, ER

    2001-01-01

    Two methods for determining the Rn-222 diffusion coefficient in concrete are presented. Experimentally, the flush and adsorption technique to measure radon release rates underlines both methods. Theoretically, the first method was developed fur samples of cubical geometry. The radon diffusion

  20. Comparative Study of Accuracy in E Speed Intra Oral Films, PSP Intra Oral Digital System and Panoramic Digital Systems (PSP&CCD for Identifying the Extent of Alveolar Bone Loss in Patients with Chronic Periodontitis

    Directory of Open Access Journals (Sweden)

    J. Moradi Haghgoo

    2014-04-01

    Full Text Available Introduction & Objective: Diagnosis of periodontal osseous lesions is very important in deter-mining prognosis, treatment plan and maintenance in the long term. This diagnosis can be achieved by using radiography. The aim of this study is to compare accuracy of E speed films, bitewing PSP, panoramic PSP and CCD for identifying the extent of destruction of al-veolar bone in chronic periodontitis. Materials & Methods: In this cross-sectional study, 272 interproximal surfaces were evaluated by 4 radiographic techniques after clinical examination by a periodontist and indication of flap surgery. The distance between CEJ and the alveolar crest was measured by Williams probe during the surgery and before osseous recontouring. These measures were considered as gold standard. This distance was measured using all 4 radiography techniques by 2 radi-ologists at standard conditions after calibration. Results: There was no significant difference between the 4 techniques. The mean distances from CEJ to alveolar crest in all techniques had no significant difference with gold standard, the least difference was in digital BW PSP and the greatest difference was in panoramic PSP. The non-measurable surfaces by E speed BW and panoramic PSP were the fewest and the most, respectively. Conclusion: Better relative accuracy with regard to variation range, mean difference of meas-ures based on gold standard and number of shown surfaces was observed in digital and conventional BW compared to digital panoramic images. (Sci J Hamadan Univ Med Sci 2014; 21 (1:41-48

  1. Thermal diffusivity measurement system applied to polymers

    Science.gov (United States)

    Abad, B.; Díaz-Chao, P.; Almarza, A.; Amantia, D.; Vázquez-Campos, S.; Isoda, Y.; Shinohara, Y.; Briones, F.; Martín-González, M. S.

    2012-06-01

    In the search for cleaner energy sources, the improvement of the efficiency of the actual ones appears as a primary objective. In this way, thermoelectric materials, which are able to convert wasted heat into electricity, are reveal as an interesting way to improve efficiency of car engines, for example. Cost-effective energy harvesting from thermoelectric devices requires materials with high electrical conductivities and Seebeck coefficient, but low thermal conductivity. Conductive polymers can fulfil these conditions if they are doped appropriately. One of the most promising polymers is Polyaniline. In this work, the thermal conductivity of the polyaniline and mixtures of polyaniline with nanoclays has been studied, using a new experimental set-up developed in the lab. The novel system is based on the steady-state method and it is used to obtain the thermal diffusivity of the polymers and the nanocomposites.

  2. Immunohistochemical localization of pancreatic spasmolytic polypeptide (PSP) in the pig

    DEFF Research Database (Denmark)

    Raaberg, Lasse; Poulsen, Steen Seier; Thim, L

    1992-01-01

    Pancreatic spasmolytic polypeptide (PSP) is a peptide that is isolated from the porcine pancreas and that affects intestinal motility and growth of intestinal tumour cells in vitro. The peptide was recently demonstrated to be present in large amounts in pancreatic juice. The cellular origin......, PSP immunoreactivity was seen in some of the cells in the epithelium of the crypts of Lieberkühn. A peptide chromatographically identical to highly purified PSP was identified in pancreas and stomach extracts. Thus epithelial cells in all parts of the stomach and small intestine contribute...

  3. A sliding cell technique for diffusion measurements in liquid metals

    OpenAIRE

    Yongliang Geng; Chunao Zhu; Bo Zhang

    2014-01-01

    The long capillary and shear cell techniques are the usual methods for diffusion measurements in liquid metals. Here we present a new “sliding cell technique” to measure interdiffusion in liquid alloys, which combines the merits of these two methods. Instead of a number of shear cells, as used in the shear cell method, only one sliding cell is designed to separate and join the liquid diffusion samples. Using the sliding cell technique, the influence of the heating process (which affects liqui...

  4. A sliding cell technique for diffusion measurements in liquid metals

    Directory of Open Access Journals (Sweden)

    Yongliang Geng

    2014-03-01

    Full Text Available The long capillary and shear cell techniques are the usual methods for diffusion measurements in liquid metals. Here we present a new “sliding cell technique” to measure interdiffusion in liquid alloys, which combines the merits of these two methods. Instead of a number of shear cells, as used in the shear cell method, only one sliding cell is designed to separate and join the liquid diffusion samples. Using the sliding cell technique, the influence of the heating process (which affects liquid diffusion measurements in the conventional long capillary method can be eliminated. Time-dependent diffusion measurements at the same isothermal temperature were carried out in Al-Cu liquids. Compared with the previous results measured by in-situ X-ray radiography, the obtained liquid diffusion coefficient in this work is believed to be influenced by convective flow. The present work further supports the idea that to obtain accurate diffusion constants in liquid metals, the measurement conditions must be well controlled, and there should be no temperature gradients or other disturbances.

  5. Diffusivity measurements of volatile organics in levitated viscous aerosol particles

    Science.gov (United States)

    Bastelberger, Sandra; Krieger, Ulrich K.; Luo, Beiping; Peter, Thomas

    2017-07-01

    Field measurements indicating that atmospheric secondary organic aerosol (SOA) particles can be present in a highly viscous, glassy state have spurred numerous studies addressing low diffusivities of water in glassy aerosols. The focus of these studies is on kinetic limitations of hygroscopic growth and the plasticizing effect of water. In contrast, much less is known about diffusion limitations of organic molecules and oxidants in viscous matrices. These may affect atmospheric chemistry and gas-particle partitioning of complex mixtures with constituents of different volatility. In this study, we quantify the diffusivity of a volatile organic in a viscous matrix. Evaporation of single particles generated from an aqueous solution of sucrose and small amounts of volatile tetraethylene glycol (PEG-4) is investigated in an electrodynamic balance at controlled relative humidity (RH) and temperature. The evaporative loss of PEG-4 as determined by Mie resonance spectroscopy is used in conjunction with a radially resolved diffusion model to retrieve translational diffusion coefficients of PEG-4. Comparison of the experimentally derived diffusivities with viscosity estimates for the ternary system reveals a breakdown of the Stokes-Einstein relationship, which has often been invoked to infer diffusivity from viscosity. The evaporation of PEG-4 shows pronounced RH and temperature dependencies and is severely depressed for RH ≲ 30 %, corresponding to diffusivities pollutant molecules such as polycyclic aromatic hydrocarbons (PAHs).

  6. MRI derived brain atrophy in PSP and MSA-P. Determining sample size to detect treatment effects.

    Science.gov (United States)

    Paviour, Dominic C; Price, Shona L; Lees, Andrew J; Fox, Nick C

    2007-04-01

    Progressive supranuclear palsy (PSP) and multiple system (MSA) atrophy are associated with progressive brain atrophy. Serial MRI can be applied in order to measure this change in brain volume and to calculate atrophy rates. We evaluated MRI derived whole brain and regional atrophy rates as potential markers of progression in PSP and the Parkinsonian variant of multiple system atrophy (MSA-P). 17 patients with PSP, 9 with MSA-P and 18 healthy controls underwent two MRI brain scans. MRI scans were registered, and brain and regional atrophy rates (midbrain, pons, cerebellum, third and lateral ventricles) measured. Sample sizes required to detect the effect of a proposed disease-modifying treatment were estimated. The effect of scan interval on the variance of the atrophy rates and sample size was assessed. Based on the calculated yearly rates of atrophy, for a drug effect equivalent to a 30% reduction in atrophy, fewer PSP subjects are required in each treatment arm when using midbrain rather than whole brain atrophy rates (183 cf. 499). Fewer MSA-P subjects are required, using pontine/cerebellar, rather than whole brain atrophy rates (164/129 cf. 794). A reduction in the variance of measured atrophy rates was observed with a longer scan interval. Regional rather than whole brain atrophy rates calculated from volumetric serial MRI brain scans in PSP and MSA-P provide a more practical and powerful means of monitoring disease progression in clinical trials.

  7. Measuring Charge Carrier Diffusion in Coupled Colloidal Quantum Dot Solids

    KAUST Repository

    Zhitomirsky, David

    2013-06-25

    Colloidal quantum dots (CQDs) are attractive materials for inexpensive, room-temperature-, and solution-processed optoelectronic devices. A high carrier diffusion length is desirable for many CQD device applications. In this work we develop two new experimental methods to investigate charge carrier diffusion in coupled CQD solids under charge-neutral, i.e., undepleted, conditions. The methods take advantage of the quantum-size-effect tunability of our materials, utilizing a smaller-bandgap population of quantum dots as a reporter system. We develop analytical models of diffusion in 1D and 3D structures that allow direct extraction of diffusion length from convenient parametric plots and purely optical measurements. We measure several CQD solids fabricated using a number of distinct methods and having significantly different doping and surface ligand treatments. We find that CQD materials recently reported to achieve a certified power conversion efficiency of 7% with hybrid organic-inorganic passivation have a diffusion length of 80 ± 10 nm. The model further allows us to extract the lifetime, trap density, mobility, and diffusion coefficient independently in each material system. This work will facilitate further progress in extending the diffusion length, ultimately leading to high-quality CQD solid semiconducting materials and improved CQD optoelectronic devices, including CQD solar cells. © 2013 American Chemical Society.

  8. Ensemble measurement of diffusion: novel beauty and evidence.

    Science.gov (United States)

    Chmelik, Christian; Heinke, Lars; Kortunov, Pavel; Li, Jing; Olson, David; Tzoulaki, Despina; Weitkamp, Jens; Kärger, Jörg

    2009-10-19

    Recording the evolution of concentration profiles in nanoporous materials opens a new field of diffusion research with particle ensembles. The technique is based on the complementary application of interference microscopy and IR micro-imaging. Combining the virtues of diffusion measurements with solids and fluids, it provides information of unprecedented wealth and visual power on transport phenomena in molecular ensembles. These phenomena include the diverging uptake and release patterns for concentration-dependent diffusivities, the mechanisms of mass transfer at the fluid-solid interface and opposing tendencies in local and global concentration evolution.

  9. Immunomodulatory and antitumor properties of polysaccharide peptide (PSP

    Directory of Open Access Journals (Sweden)

    Jakub Piotrowski

    2015-01-01

    Full Text Available Modern medicine successfully uses multiple immunomodulators of natural origin, that can affect biological reactions and support body’s natural defense mechanisms including antitumor activities. Among them is a group of products derived from fungi, including schizophyllan, lentinan, polysaccharide Krestin (PSK, and polysaccharidepeptide (PSP. Present paper is focused on polysaccharidepeptide, which due to the negligible toxicity and numerous benefits for health, is increasingly used in China and Japan as an adjuvant in the treatment of cancer. PSP is a protein-polisaccharide complex with a molecular weight 100 kDa derived from Coriolus versicolor mushroom. The results of numerous studies and clinical trials confirm that it inhibits the growth of cancer cells in in vitro and in vivo settings as well as decreases cancer treatment-related adverse side effects such as fatigue, loss of appetite, nausea, vomiting, and pain. PSP is able to restore weakened immune response observed in patients with cancer during chemotherapy. Its anti-tumor effects seemed to be mediated through immunomodulatory regulation. PSP stimulates cells of the immune system, induces synthesis of cytokines such as interleukin-1β (IL-1β, IL-6 and tumor necrosis factor-α (TNF-α, eicosanoids including prostaglandin E2 (PGE2, histamine, reactive oxygen species and nitrogen mediators. There is a growing interest in understanding the mechanisms of PSP action. Because of its unique properties and safety, PSP may become a widely used therapeutic agent in the near future.

  10. Paralytic shellfish poisoning (PSP) in Margarita Island, Venezuela.

    Science.gov (United States)

    La Barbera-Sánchez, Amelia; Franco Soler, Jose; Rojas de Astudillo, Luisa; Chang-Yen, Ivan

    2004-09-01

    A severe outbreak of Paralytic Shellfish Poisoning (PSP) occurred in Manzanillo and Guayacán, northwestern coast of Margarita Island, Venezuela, between August and October 1991. A bloom of dinoflagellates including Prorocentrum gracile, Gymnodinium catenatum and Alexandrium tamarense seemed to be responsible for this outbreak. Levels of PSP toxins in mussels (Perna perna) exceeded the international safety limit of saxitoxin, 80 microg STX/100 microg meat. PSP toxin values varied between 2548 and 115 microg STX/100 g meat in Manzanillo, and between 1422 and 86 microg STX/100 g meat in Guayacán. At both locations, the highest levels were detected in August, when 24 patients exhibited typical symptoms of PSP toxicity after consuming cooked mussels (16 required hospitalization). A high pressure liquid chromatographic (HPLC) procedure was recently used on the 1991 samples. The major toxin detected in samples of both locations was decarbamoyl saxitoxin (dcSTX), but low concentrations of saxitoxin were also found in Manzanillo samples. Gonyautoxins GTX1, GTX2 and GTX3 were detected only at Guayacán, while in both locations, decarbamoylgonyatouxin (dcGTX2,3) toxins were detected. These findings represent the first time that causative toxins of PSP in Venezuela have been chemically identified, and confirm the presence of dcSTX and dcGTX in mussels from the Caribbean Sea. The presence of dcSTX and dcGTX in shellfish is indicative that Gymnodinium catenatum was a causative organism for outbreak of PSP.

  11. Minority electron diffusion coefficient from lifetime measurement combination

    Science.gov (United States)

    Carotta, Maria Cristina; Merli, Marco; Passari, Luigi; Susi, Enrichetta

    1986-07-01

    Minority electron diffusion coefficients as a function of dopant density are evaluated from the comparison between a steady state diffusion length (photoelectromagnetic effect) and a transient lifetime (photoconductivity decay) measurement. The reliability of the method is discussed with reference to the limits inherent to the two techniques. Within the limits of the experimental data dispersion, minority values comparable to the majority ones for the doping range 3×1014

  12. Thermoelectric Measurements of Electronic Diffusivity in Bad Metals

    Science.gov (United States)

    Zhang, Jiecheng; Levenson-Falk, Eli; Kapitulnik, Aharon

    2015-03-01

    Many interesting materials, including cuprate superconductors and heavy-fermion systems, exhibit ``bad metal'' behavior at high temperatures, where the electronic mean free path is shorter than the de Broglie wavelength. Recent theory postulates that conduction in such systems is best described by collective incoherent transport, instead the standard quasiparticle model. This has implications for the temperature dependence of electronic diffusivity in these systems. We present a setup for measuring electronic diffusivity: a laser beam is focused onto a material surface and chopped, creating a periodic, concentrated heat source. The resulting thermoelectric signal is measured at various positions on the same surface with sharp voltage probes. By sweeping temperature in the range 10-450 K, we are able to measure the temperature dependence and anisotropy of the electronic diffusivity of the material. We discuss experimental improvements and measurements of cuprate superconductors. This work was funded by the Department of Energy.

  13. Measurement of light diffusion in ZnO nanowire forests

    NARCIS (Netherlands)

    Versteegh, M.A.M.; van der Wel, R.E.C.; Dijkhuis, J.I.

    2012-01-01

    Optimum design of efficient nanowire solar cells requires better understanding of light diffusion in a nanowire array. Here we demonstrate that our recently developed ultrafast all-optical shutter can be used to directly measure the dwell time of light in a nanowire array. Our measurements on

  14. Beam diffusion measurements using collimator scans in the LHC

    Directory of Open Access Journals (Sweden)

    Gianluca Valentino

    2013-02-01

    Full Text Available The time evolution of beam losses during a collimator scan provides information on halo diffusion and population. This is an essential input for machine performance characterization and for the design of collimation systems. Beam halo measurements in the CERN Large Hadron Collider were conducted through collimator scrapings in a dedicated beam study for the first time at 4 TeV. Four scans were performed with two collimators, in the vertical plane for beam 1 and horizontally for beam 2, before and after bringing the beams into collisions. Inward and outward steps were performed. A diffusion model was used to interpret the observed loss rate evolution in response to the collimator steps. With this technique, diffusion coefficients were estimated as a function of betatron oscillation amplitude from approximately 3 to 7 standard deviations of the transverse beam distribution. A comparison of halo diffusion and core emittance growth rates is also presented.

  15. Beam diffusion measurements using collimator scans in the LHC

    Science.gov (United States)

    Valentino, Gianluca; Aßmann, Ralph; Bruce, Roderik; Burkart, Florian; Previtali, Valentina; Redaelli, Stefano; Salvachua, Belen; Stancari, Giulio; Valishev, Alexander

    2013-02-01

    The time evolution of beam losses during a collimator scan provides information on halo diffusion and population. This is an essential input for machine performance characterization and for the design of collimation systems. Beam halo measurements in the CERN Large Hadron Collider were conducted through collimator scrapings in a dedicated beam study for the first time at 4 TeV. Four scans were performed with two collimators, in the vertical plane for beam 1 and horizontally for beam 2, before and after bringing the beams into collisions. Inward and outward steps were performed. A diffusion model was used to interpret the observed loss rate evolution in response to the collimator steps. With this technique, diffusion coefficients were estimated as a function of betatron oscillation amplitude from approximately 3 to 7 standard deviations of the transverse beam distribution. A comparison of halo diffusion and core emittance growth rates is also presented.

  16. [Microstructure of the lung: diffusion measurement of hyperpolarized 3Helium].

    Science.gov (United States)

    Morbach, Andreas E; Gast, Klaus K; Schmiedeskamp, Jörg; Herweling, Annette; Windirsch, Michael; Dahmen, Anja; Ley, Sebastian; Heussel, Claus-Peter; Heil, Werner; Kauczor, Hans-Ulrich; Schreiber, Wolfgang G

    2006-01-01

    Imaging methods to study the lung are traditionally based on x-ray or on radioactive contrast agents. Conventional magnetic resonance imaging (MRI) has only limited applications for lung imaging because of the low tissue density of protons concentration of hydrogen atoms, which are usually the basis for the imaging. The introduction of hyperpolarized noble gases as a contrast agent in MRI has opened new possibilities for lung diagnosis. The present paper describes this new technique. Diffusion-weighted MRI for assessment of the lung microstructure is presented here as an example of the new possibilities of functional imaging. Studies to determine the sensitivity of the diffusion measurement and regarding the correlation with traditionally established methods are also presented, along with results of the measurement of the reproducibility determined in a clinical pilot study on healthy volunteers and patients. Furthermore, a pilot measurement of the 3He diffusion tensor in the lung is presented.

  17. Measurements of the angular distribution of diffuse irradiance

    DEFF Research Database (Denmark)

    Andersen, Elsa; Nielsen, Kristian Pagh; Dragsted, Janne

    2015-01-01

    Advanced solar resource assessment and forecasting is necessary for optimal solar energy utilization. In order to investigate the short-term resource variability, for instance caused by clouds it is necessary to investigate how clouds affect the solar irradiance, including the angular distribution...... of the solar irradiance. The investigation is part of the Danish contribution to the taskforce 46 within the International Energy Agency and financed by the Danish Energy Agency. The investigation focuses on the distribution of the diffuse solar irradiance and is based on horizontal measurements of the solar...... irradiance from 8 different parts of the sky as well as horizontal measurements of the total beam and total diffuse irradiance....

  18. Geodesic-loxodromes for diffusion tensor interpolation and difference measurement.

    Science.gov (United States)

    Kindlmann, Gordon; Estépar, Raúl San José; Niethammer, Marc; Haker, Steven; Westin, Carl-Fredrik

    2007-01-01

    In algorithms for processing diffusion tensor images, two common ingredients are interpolating tensors, and measuring the distance between them. We propose a new class of interpolation paths for tensors, termed geodesic-loxodromes, which explicitly preserve clinically important tensor attributes, such as mean diffusivity or fractional anisotropy, while using basic differential geometry to interpolate tensor orientation. This contrasts with previous Riemannian and Log-Euclidean methods that preserve the determinant. Path integrals of tangents of geodesic-loxodromes generate novel measures of over-all difference between two tensors, and of difference in shape and in orientation.

  19. Water cooling thermal power measurement in a vacuum diffusion pump

    Directory of Open Access Journals (Sweden)

    Luís Henrique Cardozo Amorin

    2012-04-01

    Full Text Available Diffusion vacuum pumps are used both in industry and in laboratory science for high vacuum production. For its operation they must be refrigerated, and it is done by circulating water in open circuit. Considering that, vacuum systems stays operating by hours, the water consumption may be avoided if the diffusion vacuum pumps refrigeration were done in closed circuit. However, it is necessary to know the diffusion vacuum pump thermal power (the heat transferred to circulate water by time units to implement one of these and get in the refrigeration system dimension. In this paper the diffusion vacuum pump thermal power was obtained by measuring water flow and temperature variation and was calculated through the heat quantity variation equation time function. The thermal power value was 935,6 W, that is 397 W smaller and 35 W bigger than, respectively, the maximum and minimum diffusion pump thermal power suggested by its operation manual. This procedure have been shown useful to precisely determine the diffusion pump thermal power or of any other system that needs to be refrigerated in water closed circuit.

  20. Observation of $\\psp$ decays to $\\rho(770)\\pi$ and $\\rho(2150)\\pi$

    CERN Document Server

    Ablikim, M; Ban, Y; Bian, J G; Cai, X; Chang, J F; Chen, H F; Chen, H S; Chen, H X; Chen, J C; Chen, M L; Chen, Y B; Chi, S P; Chu, Y P; Cui, X Z; Dai, H L; Dai, Y S; Deng, Z Y; Dong, L Y; Du, S X; Du, Z Z; Fang, J; Fang, S S; Fu, C D; Fu, H Y; Gao, C S; Gao, Y N; Gong, M Y; Gong, W X; Gu, S D; Guo, Y N; Guo, Y Q; He, K L; He, M; He, X; Heng, Y K; Hu, H M; Hu, T; Huang, G S; Huang, L; Huang, X P; Ji, X B; Jia, Q Y; Jiang, C H; Jiang, X S; Jin, D P; Jin, S; Jin, Y; Lai, Y F; Li, F; Li, G; Li, H H; Li, J; Li, J C; Li, Q J; Li, R B; Li, R Y; Li, S M; Li, W G; Li, X L; Li, X Q; Li, X S; Liang, Y F; Liao, H B; Liu, C X; Liu, F; Liu, H M; Liu, J B; Liu, J P; Liu, R G; Liu, Z A; Liu, Z X; Lu, F; Lu, G R; Lu, J G; Luo, C L; Luo, X L; Ma, F C; Ma, J M; Ma, L L; Ma, Q M; Ma, X Y; Mao, Z P; Mo, X H; Nie, J; Nie, Z D; Peng, H P; Qi, N D; Qian, C D; Qin, H; Qiu, J F; Ren, Z Y; Rong, G; Shan, L Y; Shang, L; Shen, D L; Shen, X Y; Sheng, H Y; Shi, F; Shi, X; Sun, H S; Sun, S S; Sun, Y Z; Sun, Z J; Tang, X; Tao, N; Tian, Y R; Tong, G L; Wang, D Y; Wang, J Z; Wang, K; Wang, L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, S Z; Wang, W F; Wang, Y F; Wang, Z; Wang, Z Y; Wei, C L; Wei, D H; Wu, N; Wu, Y M; Xia, X M; Xie, X X; Xin, B; Xu, G F; Xu, H; Xu, Y; Xue, S T; Yan, M L; Yang, F; Yang, H X; Yang, J; Yang, S D; Yang, Y X; Ye, M; Ye, M H; Ye, Y X; Yi, L H; Yi, Z Y; Yu, C S; Yu, G W; Yuan, C Z; Yuan, J M; Yuan, Y; Yue, Q; Zang, S L; Zeng, Yu; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C C; Zhang, D H; Zhang, H Y; Zhang, J; Zhang, J Y; Zhang, J W; Zhang, L S; Zhang, Q J; Zhang, S Q; Zhang Xiao Min; Zhang, X Y; Zhang, Y J; Zhang, Y Y; Zhang, Z P; Zhang, Z Q; Zhao, D X; Zhao, J B; Zhao, J W; Zhao, M G; Zhao, P P; Zhao, W R; Zhao, X J; Zhao, Y B; Zhao, Z G; Zheng, H Q; Zheng, J P; Zheng, L S; Zheng, Z P; Zhong, X C; Zhou, B Q; Zhou, G M; Zhou, L; Zhou, N F; Zhu, K J; Zhu, Q M; Zhu, Y C; Zhu, Y S; Zhu, Z A; Zhuang, B A; Zou, B S

    2004-01-01

    \\pspto \\rho\\pi is observed for the fisrt time in a data sample of 14M \\psp decays collected by the BESII detector at BEPC. The branching fraction is measured to be \\BR(pspto\\rho\\pi)=(5.1+-0.7+-0.8)10-5, where the first error is statistical and the second one is systematic. A high mass excited \\rho state wirh mass around 2.15GeV/c2 is also observed wirh \\BR(pspto \\rho(2150)\\pi) \\ra pi+pi-pi0) =(19.4+-2.5+11.2-2.1)10-5. The branching fraction of \\pspto pi+pi-pi0 is measued with improved precision, \\BR(\\pspto pi+pi-pi0)=(18.1+-1.8+-1.9)10-5. The results may shed light on the understanding of the longstanding "\\rhopi puzzle" between \\jpsi and \\psp hadronic decays.

  1. Measurement of longitudinal electron diffusion in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yichen, E-mail: yichen@bnl.gov [Physics Department, Brookhaven National Laboratory, 20 Pennsylvania St., Building 510E, Upton, NY 11973 (United States); Tsang, Thomas [Instrumentation Division, Brookhaven National Laboratory, 20 N. Technology St., Building 535B, Upton, NY 11973 (United States); Thorn, Craig; Qian, Xin; Diwan, Milind; Joshi, Jyoti; Kettell, Steve; Morse, William [Physics Department, Brookhaven National Laboratory, 20 Pennsylvania St., Building 510E, Upton, NY 11973 (United States); Rao, Triveni [Instrumentation Division, Brookhaven National Laboratory, 20 N. Technology St., Building 535B, Upton, NY 11973 (United States); Stewart, James; Tang, Wei; Viren, Brett [Physics Department, Brookhaven National Laboratory, 20 Pennsylvania St., Building 510E, Upton, NY 11973 (United States)

    2016-04-21

    We report the measurement of longitudinal electron diffusion coefficients in liquid argon for electric fields between 100 and 2000 V/cm with a gold photocathode as a bright electron source. The measurement principle, apparatus, and data analysis are described. In the region between 100 and 350 V/cm, our results show a discrepancy with the previous measurement [1]. In the region between 350 and 2000 V/cm, our results represent the world's best measurement. Over the entire measured electric field range, our results are systematically higher than the calculation of Atrazhev‐Timoshkin [2]. The quantum efficiency of the gold photocathode, the drift velocity and longitudinal diffusion coefficients in gas argon are also presented.

  2. Real-time diameter measurement using diffuse light

    Science.gov (United States)

    Luo, Xiaohe; Hui, Mei; Zhu, Qiudong; Wang, Shanshan

    2016-09-01

    A method for on-line rapid determination of the diameter of metallic cylinder is introduced in this paper. Under the radiation of diffuse light, there is a bright area close to the margin of metallic cylinder, and the method of this paper is based on the intensity distribution of the bright area. In this paper, with the radiation by a diffuse plane light with special shape, we present the relation expression of the distance between the peak point and the real edge of the cylinder and the distance between the diffuse light and the pinhole aperture of the camera. With the expression, the diameter of the cylinder to be measured can be calculated. In the experiments, monochromatic LED uniting with ground glass forms the diffuse light source, then the light irradiates the tested cylinder. After the cylinder, we use a lens with a front pinhole stop to choose the light into CMOS, then a computer is used to analyze images and export the measurement results. The measuring system using this method is very easily implemented, so it can realize the on-line rapid measurement. Experimental results are presented for six metallic cylinders with the diameter in 5 18mm range and roughness in Ra- 0.02um, and the precision reaches 3um.

  3. Lateral diffusion on tubular membranes: quantification of measurements bias.

    Directory of Open Access Journals (Sweden)

    Marianne Renner

    Full Text Available Single Particle Tracking (SPT is a powerful technique for the analysis of the lateral diffusion of the lipid and protein components of biological membranes. In neurons, SPT allows the study of the real-time dynamics of receptors for neurotransmitters that diffuse continuously in and out synapses. In the simplest case where the membrane is flat and is parallel to the focal plane of the microscope the analysis of diffusion from SPT data is relatively straightforward. However, in most biological samples the membranes are curved, which complicates analysis and may lead to erroneous conclusions as for the mode of lateral diffusion. Here we considered the case of lateral diffusion in tubular membranes, such as axons, dendrites or the neck of dendritic spines. Monte Carlo simulations allowed us to evaluate the error in diffusion coefficient (D calculation if the curvature is not taken into account. The underestimation is determined by the diameter of the tubular surface, the frequency of image acquisition and the degree of mobility itself. We found that projected trajectories give estimates that are 25 to 50% lower than the real D in case of 2D-SPT over the tubular surface. The use of 3D-SPT improved the measurements if the frequency of image acquisition was fast enough in relation to the mobility of the molecules and the diameter of the tube. Nevertheless, the calculation of D from the components of displacements in the axis of the tubular structure gave accurate estimate of D, free of geometrical artefacts. We show the application of this approach to analyze the diffusion of a lipid on model tubular membranes and of a membrane-bound GFP on neurites from cultured rat hippocampal neurons.

  4. Measurements of charged fusion product diffusion in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R.L.

    1991-12-01

    The single particle confinement of charged fusion products, namely the 1 MeV triton and the 3 MeV proton, has been studied using a detector located near the outer midplane of TFTR. The detector, which measure the flux of escaping particles, is composed of a scintillator (ZnS(Ag)) and a system of collimating apertures, which permit pitch angle, energy and time resolution. It is mounted on a movable probe which can be inserted 25 cm into the vacuum vessel. Measurements indicate a level of losses higher than expected from a first-orbit loss mechanism alone. The primary candidate for explaining the observed anomalous losses is the toroidal field (TF) stochastic ripple diffusion, theoretically discovered by Goldston, White and Boozer. This loss mechanism is expected to be localized near the outer midplane where, at least at high current ({approx gt} 1.0 MA) it would locally dominate over first-orbit losses. Calculations made with a mapping particle orbit code (MAPLOS) show a semi-quantitative agreement with the measurements. The predominant uncertainties in the numerical simulations were found to originate from the modeling of the first wall geometry and also from the assumed plasma current and source profiles. Direct measurements of the diffusion rate were performed by shadowing the detector with a second movable probe used as an obstacle. The diffusion rate was also measured by moving the detector behind the radius of the RF limiters, located on the outer wall. Comparisons of these experimental results with numerical simulations, which include diffusive mechanisms, indicate a quantitative agreement with the TF stochastic ripple diffusion model.

  5. Measurements of charged fusion product diffusion in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, Rejean Louis [Princeton Univ., NJ (United States)

    1991-12-01

    The single particle confinement of charged fusion products, namely the 1 MeV triton and the 3 MeV proton, has been studied using a detector located near the outer midplane of TFTR. The detector, which measure the flux of escaping particles, is composed of a scintillator [ZnS(Ag)] and a system of collimating apertures, which permit pitch angle, energy and time resolution. It is mounted on a movable probe which can be inserted 25 cm into the vacuum vessel. Measurements indicate a level of losses higher than expected from a first-orbit loss mechanism alone. The primary candidate for explaining the observed anomalous losses is the toroidal field (TF) stochastic ripple diffusion, theoretically discovered by Goldston, White and Boozer. This loss mechanism is expected to be localized near the outer midplane where, at least at high current (≳ 1.0 MA) it would locally dominate over first-orbit losses. Calculations made with a mapping particle orbit code (MAPLOS) show a semi-quantitative agreement with the measurements. The predominant uncertainties in the numerical simulations were found to originate from the modeling of the first wall geometry and also from the assumed plasma current and source profiles. Direct measurements of the diffusion rate were performed by shadowing the detector with a second movable probe used as an obstacle. The diffusion rate was also measured by moving the detector behind the radius of the RF limiters, located on the outer wall. Comparisons of these experimental results with numerical simulations, which include diffusive mechanisms, indicate a quantitative agreement with the TF stochastic ripple diffusion model.

  6. Measurements of Charged Fusion Product Diffusion in Tftr

    Science.gov (United States)

    Boivin, Rejean Louis

    The single particle confinement of charged fusion products, namely the 1 MeV triton and the 3 MeV proton, has been studied using a detector located near the outer midplane of TFTR. The detector, which measures the flux of escaping particles, is composed of a scintillator (ZnS(Ag)) and a system of collimating apertures, which permit pitch angle, energy and time resolution. It is mounted on a movable probe which can be inserted 25 cm into the vacuum vessel. Measurements indicate a level of losses higher than expected from a first-orbit loss mechanism alone. The primary candidate for explaining the observed anomalous losses is the toroidal field (TF) stochastic ripple diffusion, theoretically discovered by Goldston, White and Boozer ^1. This loss mechanism is expected to be localized near the outer midplane where, at least at high current (_sp{~} {>}1.0 MA), it would locally dominate over first-orbit losses. Calculations made with a mapping particle orbit code (scMAPLOS) show a semi-quantitative agreement with the measurements. The predominant uncertainties in the numerical simulations were found to originate from the modeling of the first wall geometry and also from the assumed plasma current and source profiles. Direct measurements of the diffusion rate were performed by shadowing the detector with a second movable probe used as an obstacle. The diffusion rate was also measured by moving the detector behind the radius of the RF limiters, located on the outer wall. Comparisons of these experimental results with numerical simulations, which include diffusive mechanisms, indicate a quantitative agreement with the TF stochastic ripple diffusion model. ftn ^1R. J. Goldston, R. B. White, and A. H. Boozer, Phys. Rev. Lett. 47, 647 (1981).

  7. Experimental Measurements of Diffusivity of Vapors through Porous Substrates

    Science.gov (United States)

    Li, Hongyang; Rincon, Carlos; Bowden, Elizabeth; Zand, Ali; Sikorski, Yuri; Sanders, Matthew; Navaz, Homayun

    2007-05-01

    The release of numerous toxic chemicals, such as hydrocarbons, pesticides, chemical warfare agents, etc.; into soil, subsurface, concrete, brick and asphalt poses a great threat to the biosphere environment. The quantification and extent of spread of these chemicals has primary importance for carrying out the remediation work. There are several well known spread mechanisms which govern the mass transport in porous media. They include various regimes of liquid and vapor transport/diffusion. Modeling the transport of vapors in porous substrates requires the knowledge of the diffusivity of each particular vapor in each substrate. We present a simple, effective and inexpensive experimental method and apparatus for measurement of vapor diffusivity in porous media. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.OSS07.P1.24

  8. Measuring time-dependent diffusion in polymer matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Pilli, Siva Prasad; Smith, Lloyd V.; Shutthanandan, V.

    2014-11-01

    Moisture plays a significant role in influencing the mechanical behavior and long-term durability of polymer matrix composites (PMC’s). The common methods used to determine the moisture diffusion coefficients of PMCs are based on the solution of Fickian diffusion in the one-dimensional domain. Fick’s Law assumes that equilibrium between the material surface and the external vapor is established instantaneously. A time dependent boundary condition has been shown to improve correlation with some bulk diffusion measurements, but has not been validated experimentally. The surface moisture content in a Toray 800S/3900-2B toughened quasi-isotropic laminate system, [0/±60]s, was analyzed experimentally using Nuclear Reaction Analysis (NRA). It was found that the surface moisture content showed a rapid increase to an intermediate concentration C0, followed by a slow linear increase to the saturation level.

  9. Local diffusion and diffusion-T2distribution measurements in porous media.

    Science.gov (United States)

    Vashaee, S; Newling, B; MacMillan, B; Marica, F; Li, M; Balcom, B J

    2017-05-01

    Slice-selective pulsed field gradient (PFG) and PFG-T 2 measurements are developed to measure spatially-resolved molecular diffusion and diffusion-T 2 distributions. A spatially selective adiabatic inversion pulse was employed for slice-selection. The slice-selective pulse is able to select a coarse slice, on the order of 1cm, at an arbitrary position in the sample. The new method can be employed to characterize oil-water mixtures in porous media. The new technique has an inherent sensitivity advantage over phase encoding imaging based methods due to signal being localized from a thick slice. The method will be advantageous for magnetic resonance of porous media at low field where sensitivity is problematic. Experimental CPMG data, following PFG diffusion measurement, were compromised by a transient ΔB 0 (t) field offset. The off resonance effects of ΔB 0 (t) were examined by simulation. The ΔB 0 offset artifact in D-T 2 distribution measurements may be avoided by employing real data, instead of magnitude data. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Determination of surface relaxivity from NMR diffusion measurements.

    Science.gov (United States)

    Slijkerman, W F; Hofman, J P

    1998-01-01

    Nuclear magnetic resonance (NMR) T2-decay measurements are usually interpreted in terms of pore-size distributions. The T2 relaxation time of a water-wet pore is proportional to the size of the pore via surface relaxivity. Quantitative knowledge of the surface relaxivity is important when T2 spectra are to be used for further use such as NMR derived capillary curves. In this study, we demonstrate that surface relaxivity can be directly determined from NMR measurements. Diffusion of hydrogen spins is restricted by the pore size and this effect is independent of surface relaxivity. Hence, surface relaxivity can be determined by combining restricted diffusion and T2-relaxation. The latter two effects are measured simultaneously in a NMR T2 decay measurement performed in a static magnetic field gradient. This method generalises existing ones for uniform pore systems to full pore-size distributions of realistic rocks. We have performed laboratory NMR diffusion measurements on a number of sandstone core plugs. The surface relaxivities found from these data are compared to those obtained from other methods. This method of measuring surface relaxivity can in principle be applied to NMR data obtained in boreholes which leads to a new application of NMR logging in the characterisation of oil and gas reservoirs.

  11. Effects of Robot Assisted Gait Training in Progressive Supranuclear Palsy (PSP: a preliminary report.

    Directory of Open Access Journals (Sweden)

    Patrizio eSale

    2014-04-01

    Full Text Available Background and Purpose: Progressive supranuclear palsy (PSP is a rare neurodegenerative disease clinically characterized by prominent axial extrapyramidal motor symptoms with frequent falls. Over the last years the introduction of robotic technologies to recover lower limb function has been greatly employed in the rehabilitative practice. This observational trial is aimed at investigating the feasibility, the effectiveness and the efficacy of end-effector robot training in people with PSP.Method: Pilot observational trial.Participants: Five cognitively intact participants with PSP and gait disorders.Interventions: Patients were submitted to a rehabilitative program of robot-assisted walking sessions for 45 minutes, 5 times a week for 4 weeks.Main outcome measures: The spatiotemporal parameters at the beginning (T0 and at the end of treatment (T1 were recorded by a gait analysis laboratory.Results: Robot training was feasible, acceptable and safe and all participants completed the prescribed training sessions. All patients showed an improvement in the gait index (Mean velocity, Cadence, Step length and Step width (T0 versus T1.Conclusions: Robot training is a feasible and safe form of rehabilitation for cognitively intact people with PSP. This innovative approach can contribute to improve lower limb motor recovery. The focus on gait recovery is another quality that makes this research important for clinical practice. On the whole, the simplicity of treatment, the lack of side effects and the positive results in the patients support the recommendation to extend the trials of this treatment. Further investigation regarding the effectiveness of robot training in time is necessary.Trial registration: ClinicalTrials.gov NCT01668407.

  12. [Measurement of CO diffusion capacity (II): Standardization and quality criteria].

    Science.gov (United States)

    Salcedo Posadas, A; Villa Asensi, J R; de Mir Messa, I; Sardón Prado, O; Larramona, H

    2015-08-01

    The diffusion capacity is the technique that measures the ability of the respiratory system for gas exchange, thus allowing a diagnosis of the malfunction of the alveolar-capillary unit. The most important parameter to assess is the CO diffusion capacity (DLCO). New methods are currently being used to measure the diffusion using nitric oxide (NO). There are other methods for measuring diffusion, although in this article the single breath technique is mainly referred to, as it is the most widely used and best standardized. Its complexity, its reference equations, differences in equipment, inter-patient variability and conditions in which the DLCO is performed, lead to a wide inter-laboratory variability, although its standardization makes this a more reliable and reproductive method. The practical aspects of the technique are analyzed, by specifying the recommendations to carry out a suitable procedure, the calibration routine, calculations and adjustments. Clinical applications are also discussed. An increase in the transfer of CO occurs in diseases in which there is an increased volume of blood in the pulmonary capillaries, such as in the polycythemia and pulmonary hemorrhage. There is a decrease in DLCO in patients with alveolar volume reduction or diffusion defects, either by altered alveolar-capillary membrane (interstitial diseases) or decreased volume of blood in the pulmonary capillaries (pulmonary embolism or primary pulmonary hypertension). Other causes of decreased or increased DLCO are also highlighted. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

  13. Cumulant expansions for measuring water exchange using diffusion MRI

    Science.gov (United States)

    Ning, Lipeng; Nilsson, Markus; Lasič, Samo; Westin, Carl-Fredrik; Rathi, Yogesh

    2018-02-01

    The rate of water exchange across cell membranes is a parameter of biological interest and can be measured by diffusion magnetic resonance imaging (dMRI). In this work, we investigate a stochastic model for the diffusion-and-exchange of water molecules. This model provides a general solution for the temporal evolution of dMRI signal using any type of gradient waveform, thereby generalizing the signal expressions for the Kärger model. Moreover, we also derive a general nth order cumulant expansion of the dMRI signal accounting for water exchange, which has not been explored in earlier studies. Based on this analytical expression, we compute the cumulant expansion for dMRI signals for the special case of single diffusion encoding (SDE) and double diffusion encoding (DDE) sequences. Our results provide a theoretical guideline on optimizing experimental parameters for SDE and DDE sequences, respectively. Moreover, we show that DDE signals are more sensitive to water exchange at short-time scale but provide less attenuation at long-time scale than SDE signals. Our theoretical analysis is also validated using Monte Carlo simulations on synthetic structures.

  14. Acute and chronic changes in diffusivity measures after sports concussion.

    Science.gov (United States)

    Henry, Luke C; Tremblay, Julie; Tremblay, Sebastien; Lee, Agatha; Brun, Caroline; Lepore, Natasha; Theoret, Hugo; Ellemberg, Dave; Lassonde, Maryse

    2011-10-01

    Despite negative neuroimaging findings in concussed athletes, studies indicate that the acceleration and deceleration of the brain after concussive impacts result in metabolic and electrophysiological alterations that may be attributable to changes in white matter resulting from biomechanical strain. In the present study we investigated the effects of sports concussion on white matter using three different diffusion tensor imaging (DTI) measures: fractional anisotropy (FA), mean diffusivity (MD), and axial diffusivity (AD). We compared a group of 10 non-concussed athletes with a group of 18 concussed athletes of the same age (mean age 22.5 years) and education (mean 16 years) using a voxel-based approach (VBA) in both the acute and chronic post-injury phases. All concussed athletes were scanned 1-6 days post-concussion and again 6 months later in a 3T Siemens Trio(™) MRI. Three 2×2 repeated-measures analyses of variance (ANOVAs) were conducted, one for each measure of DTI used in the current study. There was a main group effect of FA, which was increased in dorsal regions of both corticospinal tracts (CST) and in the corpus callosum in concussed athletes at both time points. There was a main group effect of AD in the right CST, where concussed athletes showed elevated values relative to controls at both time points. MD values were decreased in concussed athletes, in whom analyses revealed significant group differences in the CST and corpus callosum at both time points. Although the use of VBA does limit the analyses to large tracts, and it has clinical limitations with regard to individual analyses, our results nevertheless indicate that sports concussions do result in changes in diffusivity in the corpus callosum and CST that are not detected using conventional neuroimaging techniques.

  15. Measurement of radon diffusion length in thin membranes.

    Science.gov (United States)

    Malki, A; Lavi, N; Moinester, M; Nassar, H; Neeman, E; Piasetzky, E; Steiner, V

    2012-07-01

    Building regulations in Israel require the insulating of buildings against radon (222)Rn penetration from soil. In radon-prone areas membranes stretched between the soil and the building foundation are used, together with sealing other possible penetration routes. Designing the radon mitigation procedure requires checking that all sealing materials are practically, radon tight, having a thickness of at least three times the radon diffusion length. In this work, a very simple technique to evaluate the radon diffusion length in thin membranes, using a radon source of known activity and an activated charcoal canister as radon detector is presented. The theoretical formalism and measurement results for polyethylene membranes of different densities obtained in a recent comparison exercise are presented.

  16. Paralytic Shellfish Poisoning (PSP in Margarita Island, Venezuela

    Directory of Open Access Journals (Sweden)

    Amelia La Barbera-Sánchez

    2004-09-01

    Full Text Available A severe outbreak of Paralytic Shellfish Poisoning (PSP occurred in Manzanillo and Guayacán, northwestern coast of Margarita Island, Venezuela, between August and October 1991. A bloom of dinoflagellates including Prorocentrum gracile, Gymnodinium catenatum and Alexandrium tamarense seemed to be responsible for this outbreak. Levels of PSP toxins in mussels (Perna perna exceeded the international safety limit of saxitoxin, 80 µg STX/100 g meat. PSP toxin values varied between 2 548 and 115 µg STX/100 g meat in Manzanillo, and between 1 422 and 86 µg STX/100 g meat in Guayacán. At both locations, the highest levels were detected in August, when 24 patients exhibited typical symptoms of PSP toxicity after consuming cooked mussels (16 required hospitalization. A high pressure liquid chromatographic (HPLC procedure was recently used on the 1991 samples. The major toxin detected in samples of both locations was decarbamoyl saxitoxin (dcSTX, but low concentrations of saxitoxin were also found in Manzanillo samples. Gonyautoxins GTX1, GTX2 and GTX3 were detected only at Guayacán, while in both locations, decarbamoylgonyatouxin (dcGTX2,3 toxins were detected. These findings represent the first time that causative toxins of PSP in Venezuela have been chemically identified, and confirm the presence of dcSTX and dcGTX in mussels from the Caribbean Sea. The presence of dcSTX and dcGTX in shellfish is indicative that Gymnodinium catenatum was a causative organism for outbreak of PSPUn severo brote de intoxicación paralizante por moluscos (PSP en inglés ocurrió en Manzanillo y Guayacán en la costa noroeste de la Isla de Margarita, Venezuela entre agosto y octubre de 1991. Una proliferación de Prorocentrum gracile, Gymnodinium catenatum y Alexandrium tamarense causó el brote. Los niveles de PSP en mejillón (Perna perna superaron los niveles máximos permisibles de saxitoxina, 80 µg STX/100g carne. Los niveles de toxinas variaron entre 2 548 y 115

  17. Effects of PspA and Antibodies to PspA on Activation and Deposition of Complement on the Pneumococcal Surface

    OpenAIRE

    Ren, Bing; Szalai, Alexander J.; Hollingshead, Susan K.; Briles, David E.

    2004-01-01

    Streptococcus pneumoniae infection is a frequent cause of pneumonia, otitis media, meningitis, and septicemia. Pneumococcal surface protein A (PspA) is an important virulence factor on the pathogen surface, and it is known to interfere with complement activation. In this study, flow cytometry was used to study the effects of PspA and antibodies to PspA on the deposition of complement C3 on the surface of a capsular type 3 strain, WU2, and its PspA− mutant, JY1119. Using naive mouse serum as a...

  18. Measurement of effective gas diffusion coefficients of catalyst layers of PEM fuel cells with a Loschmidt diffusion cell

    OpenAIRE

    Bessarabov, Dmitri; Shen, Jun; Zhou, Jianqin; Astrath, Nelson G.C.; Navessin, Titichai

    2011-01-01

    In this work, using an in-house made Loschmidt diffusion cell, we measure the effective coefficient of dry gas (O2–N2) diffusion in cathode catalyst layers of PEM fuel cells at 25 °C and 1 atmosphere. The thicknesses of the catalyst layers under investigation are from 6 to 29 μm. Each catalyst layer is deposited on an Al2O3 membrane substrate by an automated spray coater. Diffusion signal processing procedure is developed to deduce the effective diffusion coefficient, which is found to be (1....

  19. Thermal diffusivity measurement of ring specimens by infrared thermography

    Science.gov (United States)

    Ferrarini, G.; Bison, P.; Bortolin, A.; Cadelano, G.; Rossi, S.

    2017-05-01

    The thermal diffusivity of solid materials is usually measured with the well-known flash method. In the traditional setup, the tested specimens have the shape of a small disc. However, several industrial applications need to test different typologies of samples. This work is focused on ring specimens, that are widely used as joints or sealants in various applications. The goal is investigating the possibilities and limitations of the flash method, applying minimum adjustments to the traditional experimental setup. A preliminary numerical study is conducted with the creation of a finite element model. Firstly, the model is checked with the standard case of a full disk. Then the simulation investigates the case of an aluminum oxide ring, that is taken as the reference case to determine the reliability of the proposed technique. After the simulation, an experimental measurement is performed on the aluminum oxide ring reference case. Several samples are tested and useful information on the practical feasibility of the experimental setup are collected. The obtained thermal diffusivity values fall into the expected range for the material, confirming the validity of the suggested method.

  20. Measuring Lipid Membrane Viscosity Using Rotational and Translational Probe Diffusion

    Science.gov (United States)

    Hormel, Tristan T.; Kurihara, Sarah Q.; Brennan, M. Kathleen; Wozniak, Matthew C.; Parthasarathy, Raghuveer

    2014-05-01

    The two-dimensional fluidity of lipid bilayers enables the motion of membrane-bound macromolecules and is therefore crucial to biological function. Microrheological methods that measure fluid viscosity via the translational diffusion of tracer particles are challenging to apply and interpret for membranes, due to uncertainty about the local environment of the tracers. Here, we demonstrate a new technique in which determination of both the rotational and translational diffusion coefficients of membrane-linked particles enables quantification of viscosity, measurement of the effective radii of the tracers, and assessment of theoretical models of membrane hydrodynamics. Surprisingly, we find a wide distribution of effective tracer radii, presumably due to a variable number of lipids linked to each tracer particle. Furthermore, we show for the first time that a protein involved in generating membrane curvature, the vesicle trafficking protein Sar1p, dramatically increases membrane viscosity. Using the rheological method presented here, therefore, we are able to reveal a class of previously unknown couplings between protein activity and membrane mechanics.

  1. Plasmatocyte sensitivity to plasmatocyte spreading peptide (PSP) fluctuates with the larval molting cycle.

    Science.gov (United States)

    Clark, Kevin D; Kim, Y; Strand, Michael R

    2005-05-01

    Plasmatocyte spreading peptide (PSP) is a cytokine from the moth Pseudoplusia includens that activates a class of hemocytes called plasmatocytes to bind and spread on foreign surfaces. Previous structure-function studies on PSP used plasmatocytes collected from P. includens larvae that were in the late stages of the last (fifth) instar. Here, we report that plasmatocyte sensitivity to PSP varied significantly during the fourth and fifth instar. PSP weakly activated plasmatocytes early in the instar when hemolymph juvenile hormone (JH) titers were relatively high and ecdysteroid titers were low, but strongly activated plasmatocytes late in the instar after JH titers declined and ecdysteroid titers rose. In contrast, plasmatocytes did not vary in their response to plasma, which contains other factors besides PSP that affect plasmatocyte function. In vitro assays indicated that 20-hydroxyecdysone (20E) dose-dependently synergized PSP activity, whereas the JH analog methoprene antagonized PSP activity. Methoprene had no effect on adhesion and spreading of granular cells, but plasmatocytes from larvae topically treated with methoprene exhibited a reduction in sensitivity to PSP. Collectively, these results indicate that plasmatocyte sensitivity to PSP fluctuates in relation to the molting cycle, and that PSP activity is affected by juvenoids and ecdysone.

  2. Direct measurement of VOC diffusivities in tree tissues

    DEFF Research Database (Denmark)

    Baduru, K.K.; Trapp, Stefan; Burken, Joel G.

    2008-01-01

    fundamental terminal fate processes for VOCs that have been translocated from contaminated soil or groundwater, and diffusion constitutes the mass transfer mechanism to the plant−atmosphere interface. Therefore, VOC diffusion through woody plant tissues, that is, xylem, has a direct impact on contaminant fate......, and tetrachloroethane and aromatic hydrocarbons such as benzene, toluene, and methyl tert-butyl ether. All compounds tested are currently being treated at full scale with tree-based phytoremediation. Diffusivities were determined by modeling the diffusive transport data with a one-dimensional diffusive flux model...

  3. Diffusion

    OpenAIRE

    Gierl, Heribert

    1995-01-01

    Diffusion. - In: Handwörterbuch des Marketing / hrsg. von Bruno Tietz ... - 2., völlig neu gestalt. Aufl. - Stuttgart : Schäffer-Poeschel, 1995. - S. 469-477. - (Enzyklopädie der Betriebswirtschaftslehre ; 4)

  4. Measures for diffusion of solar PV in selected African countries

    DEFF Research Database (Denmark)

    Nygaard, Ivan; Hansen, Ulrich Elmer; Mackenzie, Gordon A.

    2017-01-01

    that governments’ strategies to promoting solar PV are moving from isolated projects towards frameworks for market development and that there are high expectations to upgrading in the PV value chain through local assembly of panels and local production of other system elements. Commonly identified measures include......This paper investigates how African governments are considering supporting and promoting the diffusion of solar PV. This issue is explored by examining so-called ‘technology action plans (TAPs)’, which were main outputs of the Technology Needs Assessment project implemented in 10 African countries...... from 2010 to 2013. The paper provides a review of three distinct but characteristic trajectories for PV market development in Kenya (private-led market for solar home systems), Morocco (utility-led fee-for service model) and Rwanda (donorled market for institutional systems). The paper finds...

  5. Measurement of relative permeability of fuel cell diffusion media

    KAUST Repository

    Hussaini, I.S.

    2010-06-01

    Gas diffusion layer (GDL) in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented and new correlations for in-plane relative permeability of water and air are established. © 2010 Elsevier B.V. All rights reserved.

  6. Measuring Lipid Membrane Viscosity Using Rotational and Translational Tracer Diffusion

    Science.gov (United States)

    Hormel, Tristan; Kurihara, Sarah; Reyer, Matthew; Parthasarathy, Raghuveer

    2014-03-01

    The two-dimensional fluidity of lipid membranes enables the motion of membrane-bound macromolecules and is therefore crucial to biological function. However, current methods of measuring membrane viscosity rely on particular membrane lipid compositions or geometries, making the comparison of different measurements difficult. We address this with a new technique for measuring lipid membrane viscosity, in which determination of both the rotational and translational diffusion coefficients of tracer particles enables quantification of viscosity as well as the effective size of the tracers. This technique is general, and can be applied to different model membrane systems to determine the effects of membrane composition and protein modulation. We present measurements of lipid membrane viscosity for two different lipids with phosphatidylcholine headgroups, finding a surprisingly wide distribution of effective tracer sizes, due presumably to a large variety of couplings to the membrane. We also compare the effective viscosity of two different structures - black lipid membranes and membrane multilayers - as well as changes in viscosity induced by peripheral protein binding.

  7. Unsaturated soil moisture drying and wetting diffusion coefficient measurements in the laboratory.

    Science.gov (United States)

    2009-09-01

    ABSTRACTTransient moisture flow in an unsaturated soil in response to suction changes is controlled by the unsaturated moisture diffusion coefficient. The moisture diffusion coefficient can be determined by measuring suction profiles over time. The l...

  8. Laser-saturated fluorescence measurements in laminar sooting diffusion flames

    Science.gov (United States)

    Wey, Changlie

    1993-01-01

    The hydroxyl radical is known to be one of the most important intermediate species in the combustion processes. The hydroxyl radical has also been considered a dominant oxidizer of soot particles in flames. In this investigation the hydroxyl concentration profiles in sooting diffusion flames were measured by the laser-saturated fluorescence (LSF) method. The temperature distributions in the flames were measured by the two-line LSF technique and by thermocouple. In the sooting region the OH fluorescence was too weak to make accurate temperature measurements. The hydroxyl fluorescence profiles for all four flames presented herein show that the OH fluorescence intensities peaked near the flame front. The OH fluorescence intensity dropped sharply toward the dark region of the flame and continued declining to the sooting region. The OH fluorescence profiles also indicate that the OH fluorescence decreased with increasing height in the flames for all flames investigated. Varying the oxidizer composition resulted in a corresponding variation in the maximum OH concentration and the flame temperature. Furthermore, it appears that the maximum OH concentration for each flame increased with increasing flame temperature.

  9. Personal and Social Performance (PSP scale for patients with schizophrenia: translation to Portuguese, cross-cultural adaptation and interrater reliability

    Directory of Open Access Journals (Sweden)

    Anny Karinna Pires Mendes Menezes

    2012-01-01

    Full Text Available INTRODUCTION: Schizophrenia is a chronic mental disorder associated with impairment in social functioning. The most widely used scale to measure social functioning is the GAF (Global Assessment of Functioning, but it has the disadvantage of measuring at the same time symptoms and functioning, as described in its anchors. OBJECTIVES:Translation and cultural adaptation of the PSP, proposing a final version in Portuguese for use in Brazil. METHODS: We performed five steps: 1 translation; 2 back translation; 3 formal assessment of semantic equivalence; 4 debriefing; 5 analysis by experts. Interrater reliability (Intraclass correlation, ICC between two raters was also measured. RESULTS: The final version was applied by two independent investigators in 18 adults with schizophrenia (DSM-IV-TR. The interrater reliability (ICC was 0.812 (p < 0.001. CONCLUSION: The translation and adaptation of the PSP had an adequate level of semantic equivalence between the Portuguese version and the original English version. There were no difficulties related to understanding the content expressed in the translated texts and terms. Its application was easy and it showed a good interrater reliability. The PSP is a valid instrument for the measurement of personal and social functioning in schizophrenia.

  10. Diffusion measurements in binary liquid mixtures by Raman spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Hansen, Susanne Brunsgaard; Shapiro, Alexander

    2007-01-01

    It is shown that Raman spectroscopy allows determination of the molar fractions in mixtures subjected to molecular diffusion. Spectra of three binary systems, benzene/n-hexane, benzene/cyclohexane, and benzene/ acetone, were obtained during vertical (exchange) diffusion at several different heights...... in the literature were found, even in a thermostatically controlled diffusion cell, recording spectra through circulating water. For the system benzene/acetone, the determined diffusion coefficients were in good agreement with the literature data. The limitations of the Raman method are discussed...

  11. Diffusion weighted imaging and estimation of prognosis using apparent diffusion coefficient measurements in ischemic stroke

    Energy Technology Data Exchange (ETDEWEB)

    Gonen, Korcan Aysun, E-mail: aysunbalc@yahoo.com [Department of Radiology, State Hospital, Eski Cami district, Hastane street, N:1, 59300, Tekirdag (Turkey); Simsek, Mehmet Masum, E-mail: radyoloji@haydapasanumune.gov.tr [Department of Radiology, Haydarpasa Numune Training and Research Hospital, Tibbiye street, Uskudar 34200, Istanbul (Turkey)

    2010-11-15

    Objective: Estimation of the prognosis of infarction by using diffusion weighted imaging (DWI) and quantitative apparent diffusion coefficient (ADC) measurements. Methods: 23 patients having acute stroke symptoms with verified infarction in magnetic resonance imaging (MRI) were included in this study. Their MRI studies were performed between 6 and 12 h after the onset of their symptoms and were repeated on the fifth day. The infarction volumes were calculated by using DWI and the patients were divided into two groups as the ones having an expansion in the infarction area (group 1, n = 16) and the others having no expansion in the infarction area (group 2, n = 7). Quantitative ADC values were estimated. The groups were compared in terms of the ADC values on ADC maps obtained from DWI, performed during the between 6 and 12 h from the onset of the symptoms, referring to the core of the infarction (ADC{sub IC}), ischemic penumbra (ADC{sub P}) and the nonischemic parenchymal tissue (ADC{sub N}). P values < 0.05 were accepted to be statistically significant. Results: During the between 6 and 12 h mean infarction volume calculated by DWI was 23.3 cm{sup 3} for group 1 patients (ranging from 1.1 to 68.6) and this was found to be 40.3 cm{sup 3} (ranging from 1.8 to 91.5) on the fifth day. For the group 2 patients these values were found to be 42.1 cm{sup 3} (ranging from 1 to 94.7) and 41.9 (ranging from 1 to 94.7) for the same intervals respectively. A significant statistical result was failed to be demonstrated between the mean ADC{sub IC} and ADC{sub N} values (p = 0.350 and p = 0.229 respectively). However the comparison of the ADC{sub P} values between the groups was found to be highly significant (p < 0.001). When the differences between the ADC{sub P} and ADC{sub IC} and ADC{sub N} and ADC{sub P} were compared the results proved to be statistically significant (p = 0.038 and p < 0.001 respectively). Conclusions: We believe that ADC results that would be obtained from

  12. PSP SAR interferometry monitoring of ground and structure deformations in the archeological site of Pompeii

    Science.gov (United States)

    Costantini, Mario; Francioni, Elena; Paglia, Luca; Minati, Federico; Margottini, Claudio; Spizzichino, Daniele; Trigila, Alessandro; Iadanza, Carla; De Nigris, Bruno

    2016-04-01

    The "Major Project Pompeii" (MPP) is a great collective commitment of different institututions and people to set about solving the serious problem of conservation of the largest archeological sites in the world. The ancient city of Pompeii with its 66 hectares, 44 of which are excaveted, is divided into 9 regiones (district), subdivided in 118 insulae (blocks) and almost 1500 domus (houses), and is Unesco site since 1996. The Italian Ministry for Heritage and Cultural Activities and Tourism (MiBACT) and Finmeccanica Group have sealed an agreement whereby the Finmeccanica Group will donate innovative technologies and services for monitoring and protecting the archaeological site of Pompeii. Moreover, the Italian Institute for Environment Protection and Research (ISPRA) - Geological Survey of Italy, was also involved to support the ground based analysis and interpretation of the measurements provided by the industrial team, in order to promote an interdisciplinary approach. In this work, we will focus on ground deformation measurements obtained by satellite SAR interferometry and on their interpretation. The satellite monitoring service is based on the processing of COSMO-SkyMed Himage data by the e-Geos proprietary Persistent Scatterer Pair (PSP) SAR interferometry technology. The PSP technique is a proven SAR interferometry method characterized by the fact of exploiting in the processing only the relative properties between close points (pairs) in order to overcome atmospheric artifacts (which are one of the main problems of SAR interferometry). Validations analyses showed that this technique applied to COSMO-SkyMed Himage data is able to retrieve very dense (except of course on vegetated or cultivated areas) millimetric deformation measurements with sub-metric localization. By means of the COSMO-SkyMed PSP SAR interferometry processing, a historical analysis of the ground and structure deformations occurred over the entire archaeological site of Pompeii in the

  13. Growth inhibition mediated by PSP94 or CRISP-3 is prostate cancer cell line specific.

    Science.gov (United States)

    Pathak, Bhakti R; Breed, Ananya A; Nakhawa, Vaishali H; Jagtap, Dhanashree D; Mahale, Smita D

    2010-09-01

    The prostate secretory protein of 94 amino acids (PSP94) has been shown to interact with cysteine-rich secretory protein 3 (CRISP-3) in human seminal plasma. Interestingly, PSP94 expression is reduced or lost in the majority of the prostate tumours, whereas CRISP-3 expression is upregulated in prostate cancer compared with normal prostate tissue. To obtain a better understanding of the individual roles these proteins have in prostate tumourigenesis and the functional relevance of their interaction, we ectopically expressed either PSP94 or CRISP-3 alone or PSP94 along with CRISP-3 in three prostate cell lines (PC3, WPE1-NB26 and LNCaP) and performed growth inhibition assays. Reverse transcription-polymerase chain reaction and Western blot analysis were used to screen prostate cell lines for PSP94 and CRISP-3 expression. Mammalian expression constructs for human PSP94 and CRISP-3 were also generated and the expression, localization and secretion of recombinant protein were assayed by transfection followed by Western blot analysis and immunofluorescence assay. The effect that ectopic expression of PSP94 or CRISP-3 had on cell growth was studied by clonogenic survival assay following transfection. To evaluate the effects of co-expression of the two proteins, stable clones of PC3 that expressed PSP94 were generated. They were subsequently transfected with a CRISP-3 expression construct and subjected to clonogenic survival assay. Our results showed that PSP94 and CRISP-3 could each induce growth inhibition in a cell line specific manner. Although the growth of CRISP-3-positive cell lines was inhibited by PSP94, growth inhibition mediated by CRISP-3 was not affected by the presence or absence of PSP94. This suggests that CRISP-3 may participate in PSP94-independent activities during prostate tumourigenesis.

  14. Cars temperature measurements in sooting, laminar diffusion flames

    Science.gov (United States)

    Boedeker, L. R.; Dobbs, G. M.

    1984-07-01

    Temperature distributions have been measured in axisymmetric ethylene-air diffusion flames using high spatial resolution coherent anti-Stokes Raman spectroscopy. As ethylene flow increased and the flame approached a smoke-point condition, the temperatures attained in the upper part of the flame were reduced by about 300K below the maximum radial temperatures low in the flame. Addition of diluent N2 to ethylene caused a reduction in temperature low in the flame but increased temperature higher in the flame. Maximum temperatures attained in all ethylene flames were between 0.84 and 0.89 of respective adiabatic flame temperatures (AFT). The upper temperature of the near-smoke-point flame was only 0.76 of AFT. Results are compared with the generalized flame front model of Mitchell. MIE scattering measurements are also discussed. Brief studies with propane and a nonsooting, CO flame are reported; maximum axial and radial temperatures were between 0.84 and 0.87 of AFT. Results indicate the importance of thermal loss from soot radiation, radial transport processes and fuel pyrolysis. Nonluminous radiation and finite reaction rates are other possible factors. The upper luminous part of the highly sooting ethylene flame is likely above the primary flame front and is a soot burnout zone.

  15. Comparative study of a wireless digital system and 2 PSP digital systems on proximal caries detection and pixel values.

    Science.gov (United States)

    dos Anjos Pontual, Andrea; de Melo, Daniela Pita; Pontual, Maria Luiza dos Anjos; de Almeida, Solange Maria; Haiter-Neto, Francisco

    2013-01-01

    This study compared the radiographic image quality of 2 photostimulable phosphor (PSP) plate systems with a radiographic system against a complementary metal oxide silicon (CMOS) system. Using the 3 digital systems, 160 approximal surfaces were radiographed under standardized conditions. Using a 5-point scale, 6 observers scored the resulting images for the presence of caries. The presence of caries was validated histologically, and the image receptors were evaluated using receiver operating characteristic curve analysis. The digital systems were used to take radiographs of an aluminum step wedge for objective analysis with pixel density measurements. The mean pixel values were analyzed statistically using the Kruskal-Wallis test and Dunn multiple comparison test (P < 0.01). The performance of the new CMOS system was comparable to the PSP plate systems and radiographic film.

  16. Comparison of technique errors of intraoral radiographs taken on film v photostimulable phosphor (PSP) plates.

    Science.gov (United States)

    Zhang, Wenjian; Huynh, Carolyn P; Abramovitch, Kenneth; Leon, Inga-Lill K; Arvizu, Liliana

    2012-06-01

    The objective of this study was to compare the technical errors of intraoral radiographs exposed on film v photostimulable phosphor (PSP) plates. The intraoral radiographic images exposed on phantoms from preclinical practical exams of dental and dental hygiene students were used. Each exam consisted of 10 designated periapical and bitewing views. A total of 107 film sets and 122 PSP sets were evaluated for technique errors, including placement, elongation, foreshortening, overlapping, cone cut, receptor bending, density, mounting, dot in apical area, and others. Some errors were further subcategorized as minor, major, or remake depending on the severity. The percentages of radiographs with various errors were compared between film and PSP by the Fisher's Exact Test. Compared with film, there was significantly less PSP foreshortening, elongation, and bending errors, but significantly more placement and overlapping errors. Using a wrong sized receptor due to the similarity of the color of the package sleeves is a unique PSP error. Optimum image quality is attainable with PSP plates as well as film. When switching from film to a PSP digital environment, more emphasis is necessary for placing the PSP plates, especially those with excessive packet edge, and then correcting the corresponding angulation for the beam alignment. Better design for improving intraoral visibility and easy identification of different sized PSP will improve the clinician's technical performance with this receptor.

  17. Prospects of Measuring the Angular Power Spectrum of the Diffuse ...

    Indian Academy of Sciences (India)

    The Diffuse Galactic Syncrotron Emission (DGSE) is the most important diffuse foreground component for future cosmological 21-cm observations. The DGSE is also an important probe of the cosmic ray electron and magnetic field distributions in the turbulent interstellar medium (ISM) of our galaxy. In this paper we briefly ...

  18. Estimation of the thermal diffusion coefficient in fusion plasmas taking frequency measurement uncertainties into account

    NARCIS (Netherlands)

    van Berkel, M.; Zwart, Heiko J.; Hogeweij, G.M.D.; van der Steen, G.; van den Brand, H.; de Baar, M.R.

    2014-01-01

    In this paper, the estimation of the thermal diffusivity from perturbative experiments in fusion plasmas is discussed. The measurements used to estimate the thermal diffusivity suffer from stochastic noise. Accurate estimation of the thermal diffusivity should take this into account. It will be

  19. Development of a new diffuse near-infrared food measuring

    Science.gov (United States)

    Zhang, Jun; Piao, Renguan

    2006-11-01

    Industries from agriculture to petrochemistry have found near infrared (NIR) spectroscopic analysis useful for quality control and quantitative analysis of materials and products. The general chemical, polymer chemistry, petrochemistry, agriculture, food and textile industries are currently using NIR spectroscopic methods for analysis. In this study, we developed a new sort NIR instrument for food measuring. The instrument consists of a light source, 12 filters to the prismatic part. The special part is that we use a mirror to get two beams of light. And two PbS detectors were used. One detector collected the radiation of one light beam directly and the value was set as the standard instead the standard white surface. Another light beam irradiate the sample surface, and the diffuse light was collected by another detector. The value of the two detectors was compared and the absorbency was computed. We tested the performance of the NIR instrument in determining the protein and fat content of milk powder. The calibration showed the accuracy of the instrument in practice.

  20. Diffusion characteristics of agarose hydrogel used in diffusive gradients in thin films for measurements of cations and anions.

    Science.gov (United States)

    Wang, Yan; Ding, Shiming; Gong, Mengdan; Xu, Shiwei; Xu, Weimin; Zhang, Chaosheng

    2016-11-16

    The agarose hydrogel has been increasingly used as a diffusive layer in diffusive gradients in thin films (DGT) measurements. However its diffusive characteristics have not been examined in detail. In this study, the performance of agarose gel was tested in DGT measurements of eight cations (Fe(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), and Cd(II)) and eight anions (P(V), As(V), Cr(VI), Mo(VI), Sb(V), Se(VI), V(V), and W(VI)). It was found that the thickness of agarose, a key parameter in the calculation of DGT measured concentration, remained unchanged after hydration followed by storage under the following conditions: pH 2-11, ionic strength 0-1.0 M, temperature 4-40 °C, and with the storage time extending to 300 d. Enrichment of cations and repelling of anions were observed in the gel under the ionic strengths of cations and anions through the agarose gel (plus a PVDF filter membrane) were on average 1.10 ± 0.04 times of the reported diffusion coefficients through the agarose cross-linked polyacrylamide (APA) hydrogel, typically used in DGT technique. The working pH ranges for the agarose gel-assembled DGTs were 4-10 and 5-9 for anions and cations, respectively. The use of agarose gel, either individually or along with different filter membranes, affected the overall diffusion rates of cations and anions. The measured DGT concentrations of cations and anions in filtered natural freshwater and seawater were mostly in line with those measured directly. The results showed that the agarose gel can be used as one of the standard diffusive layers in DGT measurements for a wide range of inorganic and organic analytes. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. A novel method for effective diffusion coefficient measurement in gas diffusion media of polymer electrolyte fuel cells

    Science.gov (United States)

    Yang, Linlin; Sun, Hai; Fu, Xudong; Wang, Suli; Jiang, Luhua; Sun, Gongquan

    2014-07-01

    A novel method for measuring effective diffusion coefficient of porous materials is developed. The oxygen concentration gradient is established by an air-breathing proton exchange membrane fuel cell (PEMFC). The porous sample is set in a sample holder located in the cathode plate of the PEMFC. At a given oxygen flux, the effective diffusion coefficients are related to the difference of oxygen concentration across the samples, which can be correlated with the differences of the output voltage of the PEMFC with and without inserting the sample in the cathode plate. Compared to the conventional electrical conductivity method, this method is more reliable for measuring non-wetting samples.

  2. Comparison of field-measured radon diffusion coefficients with laboratory-measured coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Lepel, E.A.; Silker, W.B.; Thomas, V.W.; Kalkwarf, D.R.

    1983-04-01

    Experiments were conducted to compare radon diffusion coefficients determined for 0.1-m depths of soils by a steady-state method in the laboratory and diffusion coefficients evaluated from radon fluxes through several-fold greater depths of the same soils covering uranium-mill tailings. The coefficients referred to diffusion in the total pore volume of the soils and are equivalent to values for the quantity, D/P, in the Generic Environmental Impact Statement on Uranium Milling prepared by the US Nuclear Regulatory Commission. Two soils were tested: a well-graded sand and an inorganic clay of low plasticity. For the flux evaluations, radon was collected by adsorption on charcoal following passive diffusion from the soil surface and also from air recirculating through an aluminum tent over the soil surface. An analysis of variance in the flux evaluations showed no significant difference between these two collection methods. Radon diffusion coefficients evaluated from field data were statistically indistinguishable, at the 95% confidence level, from those measured in the laboratory; however, the low precision of the field data prevented a sensitive validation of the laboratory measurements. From the field data, the coefficients were calculated to be 0.03 +- 0.03 cm/sup 2//s for the sand cover and 0.0036 +- 0.0004 cm/sup 2//s for the clay cover. The low precision in the coefficients evaluated from field data was attributed to high variation in radon flux with time and surface location at the field site.

  3. Holographic Measurement of the Diffusion Coefficient of Lithium Bromide in Aqueous Solution

    Science.gov (United States)

    Hattori, Masaru; Aoki, Kazuo; Yamada, Shuichi; Okubo, Takahiro

    About 90 points of diffusion coefficient of lithium bromide (LiBr) in aqueous solution were measured by holographic interferometry in the temperature range of 20∼50°C and the concentration range of 0.4∼55mass%. A correlation among concentration, temperature and diffusion coefficients was done, and an empirical equation to calculate the diffusion coefficient in the concentration and the temperature ranges mentioned above was proposed. Differences between experimental values and correlated expression were almost within±2%. Accuracy of the measured diffusion coefficients was discussed and the measurements are shown to be made within error of ±6.8%.

  4. Measurement of diffusion coefficient of liquid metals by using Gradient Heating Furnace in ISS

    OpenAIRE

    Masaki, Tadahiko; Itami, Toshio; Watanabe, Yuki; 正木 匡彦; 伊丹 俊夫; 渡辺 勇基

    2007-01-01

    The experimental techniques for the measurements of diffusion coefficient have been studied in JAXA toward the utilization of microgravity environment in ISS (International Space Station). The experimental cartridge for the gradient heating furnace, GHF (Gradient Heating Furnace), was developed for the application of shear cell which is the advanced technique of diffusion experiments. The temperature profiles of GHF were measured for the diffusion experiments and the isothermal condition can ...

  5. Thermal diffusivity measurement by lock-in photothermal shadowgraph method

    Energy Technology Data Exchange (ETDEWEB)

    Cifuentes, A. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Ciudad de México 11500 (Mexico); Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alameda Urquijo s/n, 48013 Bilbao (Spain); Alvarado, S. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Ciudad de México 11500 (Mexico); Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, Heverlee B-3001 (Belgium); Cabrera, H. [Centro Multidisciplinario de Ciencias, Instituto Venezolano de Investigaciones Científicas, IVIC, Mérida 5101, Venezuela and SPIE-ICTP Anchor Research in Optics Program Lab, International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste (Italy); Calderón, A.; Marín, E., E-mail: emarinm@ipn.mx [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Ciudad de México 11500 (Mexico)

    2016-04-28

    Here, we present a novel application of the shadowgraph technique for obtaining the thermal diffusivity of an opaque solid sample, inspired by the orthogonal skimming photothermal beam deflection technique. This new variant utilizes the shadow projected by the sample when put against a collimated light source. The sample is then heated periodically by another light beam, giving rise to thermal waves, which propagate across it and through its surroundings. Changes in the refractive index of the surrounding media due to the heating distort the shadow. This phenomenon is recorded and lock-in amplified in order to determine the sample's thermal diffusivity.

  6. Thermal diffusivity measurement of solid materials by the pulsed photothermal displacement technique

    Science.gov (United States)

    Bennis, G. L.; Vyas, R.; Gupta, R.; Ang, S.; Brown, W. D.

    1998-10-01

    A simple, noncontact technique for the measurement of thermal diffusivity of solids is experimentally demonstrated. The technique is based on the photothermal displacement effect. Excellent agreement between the quasistatic theory of photothermal displacement and the experiment has been obtained. The technique has been demonstrated by measuring the thermal diffusivities of GaAs and InGaAs/AlGaAs multiple quantum wells.

  7. In vivo magnetic resonance diffusion measurement in the brain of patients with multiple sclerosis

    DEFF Research Database (Denmark)

    Larsson, H B; Thomsen, C; Frederiksen, J

    1992-01-01

    Measurement of water self-diffusion in the brain in 25 patients with multiple sclerosis was performed by magnetic resonance imaging. Quantitative diffusion measurements were obtained using single spin-echo pulse sequences with pulsed magnetic field gradients of different magnitude. Twenty...

  8. Modeling dendrite density from magnetic resonance diffusion measurements

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Kroenke, CD; Østergaard, Leif

    2007-01-01

    .e., in extracellular space and glia cells. The model parameters are estimated from 153 diffusion-weighted images acquired from a formalin-fixed baboon brain. A close correspondence between the data and the signal model is found, with the model parameters consistent with literature values. The model provides...

  9. Thermal diffusivity measurements on porous carbon fiber reinforced polymer tubes

    Science.gov (United States)

    Gruber, Jürgen; Gresslehner, Karl Heinz; Mayr, Günther; Hendorfer, Günther

    2017-02-01

    This work presents the application of methods for the determination of the thermal diffusivity well suited for flat bodies adapted to cylindrical bodies. Green's functions were used to get the temperature time history for small and large times, for the approach of intersecting these two straight lines. To verify the theoretical considerations noise free data are generated by finite element simulations. Furthermore effects of inhomogeneous excitation and the anisotropic heat conduction of carbon fiber reinforced polymers were taken into account in these numerical simulations. It could be shown that the intersection of the two straight lines is suitable for the determination of the thermal diffusivity, although the results have to be corrected depending on the ratio of the cylinders inner and outer radii. Inhomogeneous excitation affects the results of this approach as it lead to multidimensional heat flux. However, based on the numerical simulations a range of the azimuthal angle exists, where the thermal diffusivity is nearly independent of the angle. The method to determine the thermal diffusivity for curved geometries by the well suited Thermographic Signal Reconstruction method and taking into account deviations from the slab by a single correction factor has great advantages from an industrial point of view, just like an easy implementation into evaluation software and the Thermographic Signal Reconstruction methods rather short processing time.

  10. Measurement of thermal conductivity and diffusivity in situ: Literature survey and theoretical modelling of measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kukkonen, I.; Suppala, I. [Geological Survey of Finland, Espoo (Finland)

    1999-01-01

    In situ measurements of thermal conductivity and diffusivity of bedrock were investigated with the aid of a literature survey and theoretical simulations of a measurement system. According to the surveyed literature, in situ methods can be divided into `active` drill hole methods, and `passive` indirect methods utilizing other drill hole measurements together with cutting samples and petrophysical relationships. The most common active drill hole method is a cylindrical heat producing probe whose temperature is registered as a function of time. The temperature response can be calculated and interpreted with the aid of analytical solutions of the cylindrical heat conduction equation, particularly the solution for an infinite perfectly conducting cylindrical probe in a homogeneous medium, and the solution for a line source of heat in a medium. Using both forward and inverse modellings, a theoretical measurement system was analysed with an aim at finding the basic parameters for construction of a practical measurement system. The results indicate that thermal conductivity can be relatively well estimated with borehole measurements, whereas thermal diffusivity is much more sensitive to various disturbing factors, such as thermal contact resistance and variations in probe parameters. In addition, the three-dimensional conduction effects were investigated to find out the magnitude of axial `leak` of heat in long-duration experiments. The radius of influence of a drill hole measurement is mainly dependent on the duration of the experiment. Assuming typical conductivity and diffusivity values of crystalline rocks, the measurement yields information within less than a metre from the drill hole, when the experiment lasts about 24 hours. We propose the following factors to be taken as basic parameters in the construction of a practical measurement system: the probe length 1.5-2 m, heating power 5-20 Wm{sup -1}, temperature recording with 5-7 sensors placed along the probe, and

  11. In vivo measurement of water self diffusion in the human brain by magnetic resonance imaging

    DEFF Research Database (Denmark)

    Thomsen, C; Henriksen, O; Ring, P

    1987-01-01

    coefficient of water with different temperatures. This phantom study showed that the water self diffusion could be measured accurately and that the inplane deviation was less than +/- 10 per cent. Seven healthy volunteers were studied with a 10 mm thick slice through the lateral ventricles, clear differences......A new pulse sequence for in vivo diffusion measurements by magnetic resonance imaging (MRI) is introduced. The pulse sequence was tested on phantoms to evaluate the accuracy, reproducibility and inplane variations. The sensitivity of the sequence was tested by measuring the self diffusion...... intracranial hypertension. The results indicate that brain water self diffusion can be measured in vivo with reasonable accuracy. The clinical examples suggest that diffusion measurements may be clinically useful adding further information about in vivo MR tissue characterization....

  12. NMR-based diffusion pore imaging by double wave vector measurements.

    Science.gov (United States)

    Kuder, Tristan Anselm; Laun, Frederik Bernd

    2013-09-01

    One main interest of nuclear magnetic resonance (NMR) diffusion experiments is the investigation of boundaries such as cell membranes hindering the diffusion process. NMR diffusion measurements allow collecting the signal from the whole sample. This mainly eliminates the problem of vanishing signal at increasing resolution. It has been a longstanding question if, in principle, the exact shape of closed pores can be determined by NMR diffusion measurements. In this work, we present a method using short diffusion gradient pulses only, which is able to reveal the shape of arbitrary closed pores without relying on a priori knowledge. In comparison to former approaches, the method has reduced demands on relaxation times due to faster convergence to the diffusion long-time limit and allows for a more flexible NMR sequence design, because, e.g., stimulated echoes can be used. Copyright © 2012 Wiley Periodicals, Inc.

  13. Measures for diffusion of solar PV in selected African countries

    OpenAIRE

    Nygaard, Ivan; Hansen, Ulrich Elmer; Mackenzie, Gordon A.; Pedersen, Mathilde Brix

    2017-01-01

    This paper investigates how African governments are considering supporting and promoting the diffusion of solar PV. This issue is explored by examining so-called ‘technology action plans (TAPs)’, which were main outputs of the Technology Needs Assessment project implemented in 10 African countries from 2010 to 2013. The paper provides a review of three distinct but characteristic trajectories for PV market development in Kenya (private-led market for solar home systems), Morocco (utility-led ...

  14. Proposal of novel measurement method for thermal diffusivity from infrared thermal movie

    Science.gov (United States)

    Okamoto, Yoichi; Watanabe, Shin; Ogata, Kento; Hiramatsu, Koji; Miyazaki, Hisashi; Morimoto, Jun

    2017-05-01

    A brand new thermal diffusivity measurement method was developed. In this new noncontact and absolute measurement method, thermal diffusivity was measured from infrared movie data. The model of one-dimensional thermal conduction was constructed by taking into account the thermal flow other than one-dimensional thermal conduction in the sample. On the basis of this thermal conduction model, the analytical equation for calculating thermal diffusivity was derived. A single-crystal sapphire plate was used as a test specimen for the new method. The test specimen was arranged to cause one-dimensional heat conduction. Infrared movies were taken by using an infrared camera at room temperature. Then, thermal diffusivity was numerically calculated from the acquired movie data using the analytical equation. It was experimentally demonstrated that thermal diffusivity was measured with an accuracy of around 10% error, from an infrared movie of a single-crystal sapphire sample.

  15. Rapid yet accurate measurement of mass diffusion coefficients by phase shifting interferometer

    CERN Document Server

    Guo Zhi Xiong; Komiya, A

    1999-01-01

    The technique of using a phase-shifting interferometer is applied to the study of diffusion in transparent liquid mixtures. A quick method is proposed for determining the diffusion coefficient from the measurements of the location of fringes on a grey level picture. The measurement time is very short (within 100 s) and a very small transient diffusion field can be observed and recorded accurately with a rate of 30 frames per second. The measurement can be completed using less than 0.12 cc of solutions. The influence of gravity on the measurement of the diffusion coefficient is eliminated in the present method. Results on NaCl-water diffusion systems are presented and compared with the reference data. (author)

  16. New sensitive micro-measurements of dynamic surface tension and diffusion coefficients

    DEFF Research Database (Denmark)

    Kinoshita, Koji; Ortiz, Elisa Parra; Needham, David

    2017-01-01

    Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain “dead time” at initial measurement...... for surface excess concentration. We found that the measured diffusion coefficient of 1-Octanol, 7.2 ± 0.8 × 10−6 cm2/s, showed excellent agreement with the result from an alternative method, “single microdroplet catching method”, to measure the diffusion coefficient from diffusion-controlled microdroplet...

  17. Plasmatocyte spreading peptide (PSP1) and growth blocking peptide (GBP) are multifunctional homologs.

    Science.gov (United States)

    Strand; Hayakawa; Clark

    2000-05-01

    Recently, we identified Plasmatocyte spreading peptide (PSP1) from the moth Pseudoplusia includens and reported that it mediates adhesion of hemocytes to foreign surfaces. PSP1 is structurally very similar to three classes of peptides identified earlier from other species of Lepidoptera: growth blocking peptide (GBP) originally identified in Pseudaletia separata, and a series of related peptides from other species designated as paralytic (PP) or cardioactive (CAP) peptides. In this study, we conducted parallel experiments in P. includens and P. separata to determine whether PSP1 and GBP have distinct or multiple biological activities. Both peptides affected the adhesive state of hemocytes from each moth very similarly. PSP1 and GBP exhibited significant growth blocking and paralytic activity in P. separata. Both peptides also had growth blocking activity in P. includens although larvae had to be injected with higher doses of each peptide to reduce weight gain than was observed for P. separata. However, GBP and PSP1 had little paralytic activity in P. includens. Collectively, our results indicate that GBP and PSP1 are multifunctional, but that some interspecific variation also exists in their growth blocking and paralytic activities. We suggest that all PSP1, GBP, PP and CAP family members are homologs that likely have multiple biological activities. Based upon the unique consensus sequence of their N termini, we propose that these molecules be henceforth referred to as members of the "ENF" peptide family.

  18. Contrasting physiological responses of two populations of the razor clam Tagelus dombeii with different histories of exposure to paralytic shellfish poisoning (PSP).

    Science.gov (United States)

    Navarro, Jorge M; González, Katerina; Cisternas, Barbara; López, Jorge A; Chaparro, Oscar R; Segura, Cristian J; Córdova, Marco; Suárez-Isla, Benjamín; Fernandez-Reiriz, María J; Labarta, Uxio

    2014-01-01

    This study describes the physiological performance of two populations of the razor clam Tagelus dombeii from two geographic areas with different histories of exposure to paralytic shellfish poisoning (PSP) linked to the toxic dinoflagellate Alexandrium catenella. Clams from Melinka-Aysén, which are frequently exposed to PSP, were not affected by the presence of toxins in the diet. However, clams from Corral-Valdivia, which have never been exposed to PSP, exhibited significantly reduced filtration activity and absorption, affecting the energy allocated to scope for growth (SFG). Ammonia excretion and oxygen uptake were not affected significantly by the presence of A. catenella in the diet. Measurements of energy acquisition and expenditure were performed during a 12-day intoxication period. According to three-way repeated measure ANOVAs, the origin of the clams had a highly significant effect on all physiological variables, and the interaction between diet and origin was significant for the clearance and absorption rates and for the scope for growth. The scope for growth index showed similar positive values for both the toxic and non-toxic individuals from the Melinka-Aysén population. However, it was significantly reduced in individuals from Corral-Valdivia when exposed to the diet containing A. catenella. The absence of differences between the physiological response of the toxic and non-toxic clams from Melinka-Aysén may be related to the frequent presence of A. catenella in the environment, indicating that this bivalve does not suffer negative consequences from PSP. By contrast, A. catenella has a negative effect on the physiological performance, primarily on the energy gained from the environment, on T. dombeii from Corral-Valdivia. This study supports the hypothesis that the history of PSP exposure plays an important role in the physiological performance and fitness of filter feeding bivalves.

  19. In vivo measurement of water self diffusion in the human brain by magnetic resonance imaging

    DEFF Research Database (Denmark)

    Thomsen, C; Henriksen, O; Ring, P

    1987-01-01

    A new pulse sequence for in vivo diffusion measurements by magnetic resonance imaging (MRI) is introduced. The pulse sequence was tested on phantoms to evaluate the accuracy, reproducibility and inplane variations. The sensitivity of the sequence was tested by measuring the self diffusion...... coefficient of water with different temperatures. This phantom study showed that the water self diffusion could be measured accurately and that the inplane deviation was less than +/- 10 per cent. Seven healthy volunteers were studied with a 10 mm thick slice through the lateral ventricles, clear differences...... between grey and white matter as well as regional differences within the white matter were seen. In two patients with infarction, alternations in water self diffusion were seen in the region of the infarct. Likewise, pronounced changes in brain water self diffusion were observed in a patient with benign...

  20. Measurement of biomolecular diffusion in extracellular matrix condensed by fibroblasts using fluorescence correlation spectroscopy.

    Directory of Open Access Journals (Sweden)

    Takanori Kihara

    Full Text Available The extracellular matrix (ECM comprises the heterogeneous environment outside of cells in a biological system. The ECM is dynamically organized and regulated, and many biomolecules secreted from cells diffuse throughout the ECM, regulating a variety of cellular processes. Therefore, investigation of the diffusive behaviors of biomolecules in the extracellular environment is critical. In this study, we investigated the diffusion coefficients of biomolecules of various sizes, measuring from 1 to 10 nm in radius, by fluorescence correlation spectroscopy in contracted collagen gel caused by fibroblasts, a traditional culture model of dynamic rearrangement of collagen fibers. The diffusion coefficients of the biomolecules in control collagen gel without cells decreased slightly as compared to those in solution, while the diffusion coefficients of biomolecules in the contracted gel at the cell vicinity decreased dramatically. Additionally, the diffusion coefficients of biomolecules were inversely correlated with molecular radius. In collagen gels populated with fibroblasts, the diffusion coefficient at the cell vicinity clearly decreased in the first 24 h of culture. Furthermore, molecular diffusion was greatly restricted, with a central focus on the populated cells. By using the obtained diffusion coefficients of biomolecules, we calculated the collagen fiber condensation ratio by fibroblasts in the cell vicinity at 3 days of culture to represent a 52-fold concentration. Thus, biomolecular diffusion is restricted in the vicinity of the cells where collagen fibers are highly condensed.

  1. A Simple Educational Method for the Measurement of Liquid Binary Diffusivities

    Science.gov (United States)

    Rice, Nicholas P.; de Beer, Martin P.; Williamson, Mark E.

    2014-01-01

    A simple low-cost experiment has been developed for the measurement of the binary diffusion coefficients of liquid substances. The experiment is suitable for demonstrating molecular diffusion to small or large undergraduate classes in chemistry or chemical engineering. Students use a cell phone camera in conjunction with open-source image…

  2. Diffusivity measurements in some organic solvents by a gas-liquid diaphragm cell

    NARCIS (Netherlands)

    Littel, R.J.; Littel, R.J.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1992-01-01

    A diaphragm cell has been developed for the measurement of diffusion coefficients of gases In liquids. The diaphragm cell is operated batchwise with respect to both gas and liquid phases, and the diffusion process Is followed by means of the gas pressure decrease which is recorded by means of a

  3. Diffusivity Measurements in Some Organic Solvents by a Gas-Liquid Diaphragm Cell

    NARCIS (Netherlands)

    Littel, Rob J.; Versteeg, Geert F.; Swaaij, Wim P.M. van

    1992-01-01

    A diaphragm cell has been developed for the measurement of diffusion coefficients of gases in liquids. The diaphragm cell is operated batchwise with respect to both gas and liquid phases, and the diffusion process is followed by means of the gas pressure decrease which is recorded by means of a

  4. Analysis and correction of gradient nonlinearity bias in apparent diffusion coefficient measurements.

    Science.gov (United States)

    Malyarenko, Dariya I; Ross, Brian D; Chenevert, Thomas L

    2014-03-01

    Gradient nonlinearity of MRI systems leads to spatially dependent b-values and consequently high non-uniformity errors (10-20%) in apparent diffusion coefficient (ADC) measurements over clinically relevant field-of-views. This work seeks practical correction procedure that effectively reduces observed ADC bias for media of arbitrary anisotropy in the fewest measurements. All-inclusive bias analysis considers spatial and time-domain cross-terms for diffusion and imaging gradients. The proposed correction is based on rotation of the gradient nonlinearity tensor into the diffusion gradient frame where spatial bias of b-matrix can be approximated by its Euclidean norm. Correction efficiency of the proposed procedure is numerically evaluated for a range of model diffusion tensor anisotropies and orientations. Spatial dependence of nonlinearity correction terms accounts for the bulk (75-95%) of ADC bias for FA = 0.3-0.9. Residual ADC non-uniformity errors are amplified for anisotropic diffusion. This approximation obviates need for full diffusion tensor measurement and diagonalization to derive a corrected ADC. Practical scenarios are outlined for implementation of the correction on clinical MRI systems. The proposed simplified correction algorithm appears sufficient to control ADC non-uniformity errors in clinical studies using three orthogonal diffusion measurements. The most efficient reduction of ADC bias for anisotropic medium is achieved with non-lab-based diffusion gradients. Copyright © 2013 Wiley Periodicals, Inc.

  5. Estimation and prediction of convection-diffusion-reaction systems from point measurement

    NARCIS (Netherlands)

    Vries, D.

    2008-01-01

    Different procedures with respect to estimation and prediction of systems characterized by convection, diffusion and reactions on the basis of point measurement data, have been studied. Two applications of these convection-diffusion-reaction (CDR) systems have been used as a case study of the

  6. Measurement and Analysis of the Diffusible Hydrogen in Underwater Wet Welding Joint

    Directory of Open Access Journals (Sweden)

    Kong Xiangfeng

    2016-01-01

    Full Text Available The diffusible hydrogen in steel weldments is one of the main reasons that led to hydrogen assisted cracking. In this paper, the results of literatures survey and preliminary tests of the diffusible hydrogen in underwater wet welding joint were presented. A fluid-discharge method of for measuring the diffusible hydrogen in weldment was introduced in detail. Two kinds of underwater welding electrode diffusible hydrogen are 26.5 mL/100g and 35.5 mL/100g by fluid-discharge method, which are high levels. The diffusible hydrogen of underwater welding is higher than atmospheric welding, and the result is closely related to welding material. The best way to control the diffusible hydrogen is adjusting welding material and improving fluidity of slag.

  7. Measurement and modeling of CO2 diffusion coefficient in Saline Aquifer at reservoir conditions

    Science.gov (United States)

    Azin, Reza; Mahmoudy, Mohamad; Raad, Seyed; Osfouri, Shahriar

    2013-12-01

    Storage of CO2 in deep saline aquifers is a promising techniques to mitigate global warming and reduce greenhouse gases (GHG). Correct measurement of diffusivity is essential for predicting rate of transfer and cumulative amount of trapped gas. Little information is available on diffusion of GHG in saline aquifers. In this study, diffusivity of CO2 into a saline aquifer taken from oil field was measured and modeled. Equilibrium concentration of CO2 at gas-liquid interface was determined using Henry's law. Experimental measurements were reported at temperature and pressure ranges of 32-50°C and 5900-6900 kPa, respectively. Results show that diffusivity of CO2 varies between 3.52-5.98×10-9 m2/s for 5900 kPa and 5.33-6.16×10-9 m2/s for 6900 kPa initial pressure. Also, it was found that both pressure and temperature have a positive impact on the measures of diffusion coefficient. Liquid swelling due to gas dissolution and variations in gas compressibility factor as a result of pressure decay was found negligible. Measured diffusivities were used model the physical model and develop concentration profile of dissolved gas in the liquid phase. Results of this study provide unique measures of CO2 diffusion coefficient in saline aquifer at high pressure and temperature conditions, which can be applied in full-field studies of carbon capture and sequestration projects.

  8. The Measurement of Thermal Diffusivity in Conductor and Insulator by Photodeflection Technique

    Science.gov (United States)

    Achathongsuk, U.; Rittidach, T.; Tipmonta, P.; Kijamnajsuk, P.; Chotikaprakhan, S.

    2017-09-01

    The purpose of this study is to estimate thermal diffusivities of high thermal diffusivity bulk material as well as low thermal diffusivity bulk material by using many types of fluid such as Ethyl alcohol and water. This method is studied by measuring amplitude and phase of photodeflection signal in various frequency modulations. The experimental setup consists of two laser lines: 1) a pump laser beams through a modulator, varied frequency, controlled by lock-in amplifier and focused on sample surface by lens. 2) a probe laser which parallels with the sample surface and is perpendicular to the pump laser beam. The probe laser deflection signal is obtained by a position sensor which controlled by lock-in amplifier. Thermal diffusivity is calculated by measuring the amplitude and phase of the photodeflection signal and compared with the thermal diffusivity of a standard value. The thermal diffusivity of SGG agrees well with the literature but the thermal diffusivity of Cu is less than the literature value by a factor of ten. The experiment requires further improvement to measure the thermal diffusivity of Cu. However, we succeed in using ethyl alcohol as the coupling medium instead of CCl4 which is highly toxic.

  9. A multi-slice sliding cell technique for diffusion measurements in liquid metals

    Science.gov (United States)

    Zhong, Langxiang; Hu, Jinliang; Geng, Yongliang; Zhu, Chunao; Zhang, Bo

    2017-09-01

    The long capillary and shear-cell techniques are traditionally used for diffusion measurements in liquid metals. Inspired by the idea of the shear-cell method, we have built a multi-slice sliding cell device for inter-diffusion measurements in liquid metals. The device is designed based on a linear sliding movement rather than a rotational shearing as used in the traditional shear-cell method. Compared with the normal shear-cell method, the present device is a more compact setup thus easier to handle. Also, it is expected to be easier to monitor with X-rays or neutrons if used in in situ experiments. A series of benchmark time-dependent diffusion experiments in Al-Cu melts carried out with the present technique reveal that accurate diffusion constants can be achieved only after a sufficient time. For short annealing times, the initial shearing process causing convective flow dominates the measurement and leads to an increase of the measured diffusion coefficient by a factor three. The diffusion data obtained for Al-Cu liquids are consistent with the most accurate data measured by the in situ X-ray radiography method under well controlled conditions of no temperature gradient or other perturbation. High accuracy and easy handling as well as superior adaptability make the present technique suitable for diffusion studies in liquid metals.

  10. Measurement of diffusion coefficient of propylene glycol in skin tissue

    Science.gov (United States)

    Genin, Vadim D.; Bashkatov, Alexey N.; Genina, Elina A.; Tuchin, Valery V.

    2015-03-01

    Optical clearing of the rat skin under the action of propylene glycol was studied ex vivo. It was found that collimated transmittance of skin samples increased, whereas weight and thickness of the samples decreased during propylene glycol penetration in skin tissue. A mechanism of the optical clearing under the action of propylene glycol is discussed. Diffusion coefficient of propylene glycol in skin tissue ex vivo has been estimated as (1.35±0.95)×10-7 cm2/s with the taking into account of kinetics of both weight and thickness of skin samples. The presented results can be useful for enhancement of many methods of laser therapy and optical diagnostics of skin diseases and localization of subcutaneous neoplasms.

  11. Hanford 67-series: a volume of atmospheric field diffusion measurements

    Energy Technology Data Exchange (ETDEWEB)

    Nickola, P.W.

    1977-11-01

    This volume documents atmospheric diffusion experiments carried out at the Hanford reservation during the period 1967 to 1973. A total of 103 tracer releases during 54 release periods is tabulated. Multi-tracer releases (generally from different elevations) were made during most of the experimental periods. Release heights varied from ground level to an elevation of 111 m. Tracers were sampled simultaneously on as many as 10 arcs at distances of up to 12.8 km from the tracer release point. As many as 718 field sampling locations were employed during some of the experiments. Vertical profiles of concentration were monitored on towers during 23 of the 54 release periods. Concurrent vertical profiles of mean temperature, of mean wind speed and direction, and of direction standard deviation are also tabled for elevations up to 122 m.

  12. In vivo measurement of brain extracellular space diffusion by cortical surface photobleaching.

    Science.gov (United States)

    Binder, Devin K; Papadopoulos, Marios C; Haggie, Peter M; Verkman, A S

    2004-09-15

    Molecular diffusion in the brain extracellular space (ECS) is an important determinant of neural function. We developed a brain surface photobleaching method to measure the diffusion of fluorescently labeled macromolecules in the ECS of the cerebral cortex. The ECS in mouse brain was labeled by exposure of the intact dura to fluorescein-dextrans (M(r) 4, 70, and 500 kDa). Fluorescein-dextran diffusion, detected by fluorescence recovery after laser-induced cortical photobleaching using confocal optics, was slowed approximately threefold in the brain ECS relative to solution. Cytotoxic brain edema (produced by water intoxication) or seizure activity (produced by convulsants) slowed diffusion by >10-fold and created dead-space microdomains in which free diffusion was prevented. The hindrance to diffusion was greater for the larger fluorescein-dextrans. Interestingly, slowed ECS diffusion preceded electroencephalographic seizure activity. In contrast to the slowed diffusion produced by brain edema and seizure activity, diffusion in the ECS was faster in mice lacking aquaporin-4 (AQP4), an astroglial water channel that facilitates fluid movement between cells and the ECS. Our results establish a minimally invasive method to quantify diffusion in the brain ECS in vivo, revealing stimulus-induced changes in molecular diffusion in the ECS with unprecedented spatial and temporal resolution. The in vivo mouse data provide evidence for: (1) dead-space ECS microdomains after brain swelling; (2) slowed molecular diffusion in the ECS as an early predictor of impending seizure activity; and (3) a novel role for AQP4 as a regulator of brain ECS.

  13. Detection of pregnancy by radioimmunoassay of a pregnancy serum protein (PSP60) in cattle

    Energy Technology Data Exchange (ETDEWEB)

    Mialon, M.M.; Renand, G.; Camous, S.; Martal, J.; Menissier, F. (Institut National de Recherches Agronomiques (INRA), 78 - Jouy-en-Josas (France))

    1994-01-01

    The accuracy and efficiency of pregnancy diagnoses in cattle by pregnancy serum protein (PSP60) radioimmunoassay, a progesterone radioimmunoassay or oestrus detection were compared. Blood samples were taken from 349 suckling heifers and cows ( 1 191 inseminations) at 28, 35, 50 and 90 d post-insemination for PSP60 determination and at 22-23 d for progesterone. Females were declared nonpregnant when plasma PSP60 concentration was lower than 0.2 ng/ml at 28, 35 and 50 d and 0.5 ng/ml at 90 d. When compared with rectal palpation at 90 d, the accuracy of positive (negative) diagnoses by progesterone assay was 80% (100%) in heifers and 75% (99%) in cows. The accuracy of positive diagnoses by PSP60 assay increased with gestation stage from 90% on d 28 in heifers (74% in cows) to 100% (99% in cows) at the time of rectal palpation. This accuracy was 84% on d 28 in cows when the interval from calving to blood sampling was higher than 115 d. Whatever the stage, the accuracy of negative diagnoses was higher than 90%. Efficiency in detecting pregnant or nonpregnant females on d 28 was equivalent to the progesterone assay. The method for detecting oestrus applied in this experiment was as efficient as the PSP60 or progesterone test at any stage of gestation. The PSP60 test is very flexible, which makes its use particularly interesting in naturally mated suckling herds because of the uncertainty regarding the date of fertilization. (authors).

  14. Time Resolved Thermal Diffusivity of Seasonal Snow Determined from Inexpensive, Easily-Implemented Temperature Measurements

    Science.gov (United States)

    Oldroyd, H. J.; Higgins, C. W.; Huwald, H.; Selker, J. S.; Parlange, M. B.

    2011-12-01

    Thermal diffusivity of snow is an important physical property associated with key hydrological phenomena such as snow melt and heat and water vapor exchange with the atmosphere. These phenomena have broad implications in studies of climate and heat and water budgets on many scales. However, direct measurements of snow thermal diffusivity require coupled point measurements of thermal conductivity and density, which are nonstationary due to snow metamorphism. Furthermore, thermal conductivity measurements are typically obtained with specialized heating probes or plates and snow density measurements require digging snow pits. Therefore, direct measurements are difficult to obtain with high enough temporal resolution such that direct comparisons with atmospheric conditions can be made. This study uses highly resolved (7.5 to 10 cm for depth and 1min for time) temperature measurements from the Plaine Morte glacier in Switzerland as initial and boundary conditions to numerically solve the 1D heat equation and iteratively optimize for thermal diffusivity. The method uses flux boundary conditions to constrain thermal diffusivity such that spuriously high values in thermal diffusivity are eliminated. Additionally, a t-test ensuring statistical significance between solutions of varied thermal diffusivity result in further constraints on thermal diffusivity that eliminate spuriously low values. The results show that time resolved (1 minute) thermal diffusivity can be determined from easily implemented and inexpensive temperature measurements of seasonal snow with good agreement to widely used parameterizations based on snow density. This high time resolution further affords the ability to explore possible turbulence-induced enhancements to heat and mass transfer in the snow.

  15. PSP SAR interferometry monitoring of ground and structure deformations applied to archaeological sites

    Science.gov (United States)

    Costantini, Mario; Francioni, Elena; Trillo, Francesco; Minati, Federico; Margottini, Claudio; Spizzichino, Daniele; Trigila, Alessandro; Iadanza, Carla

    2017-04-01

    Archaeological sites and cultural heritage are considered as critical assets for the society, representing not only the history of region or a culture, but also contributing to create a common identity of people living in a certain region. In this view, it is becoming more and more urgent to preserve them from climate changes effect and in general from their degradation. These structures are usually just as precious as fragile: remote sensing technology can be useful to monitor these treasures. In this work, we will focus on ground deformation measurements obtained by satellite SAR interferometry and on the methodology adopted and implemented in order to use the results operatively for conservation policies in a Italian archaeological site. The analysis is based on the processing of COSMO-SkyMed Himage data by the e-GEOS proprietary Persistent Scatterer Pair (PSP) SAR interferometry technology. The PSP technique is a proven SAR interferometry technology characterized by the fact of exploiting in the processing only the relative properties between close points (pairs) in order to overcome atmospheric artefacts (which are one of the main problems of SAR interferometry). Validations analyses [Costantini et al. 2015] settled that this technique applied to COSMO-SkyMed Himage data is able to retrieve very dense (except of course on vegetated or cultivated areas) millimetric deformation measurements with sub-metric localization. Considering the limitations of all the interferometric techniques, in particular the fact that the measurement are along the line of sight (LOS) and the geometric distortions, in order to obtain the maximum information from interferometric analysis, both ascending and descending geometry have been used. The ascending analysis allows selecting measurements points over the top and, approximately, South-West part of the structures, while the descending one over the top and the South-East part of the structures. The interferometric techniques needs

  16. A travelling photothermal technique employing pyroelectric detection to measure thermal diffusivity of films and coatings

    Science.gov (United States)

    Philip, J.; Manjusha, M. V.; Soumya, H.

    2011-10-01

    A travelling thermal wave technique employing optical excitation and pyroelectric detection of thermal waves propagating along a material film/coating on a substrate is described. The method enables direct measurement of thermal diffusivity. The technique involves measurement of the phase lag undergone by an optically excited thermal wave as it propagates along the coating. The set up has been automated for convenient and fast data acquisition and analysis. The technique has been adapted to measurement of thermal diffusivity of a commercial paint sample coated on glass and copper substrates. It is found that thermal diffusivity of the coating is independent of the thermal conductivity of the substrate. Dependence of thermal diffusivity on coating thickness shows exponential increase, with value reaching a constant at a characteristic high thickness. Measurements have been carried out on a few other samples with wide variations in thermal diffusivity, and the results compared with available reports or results obtained following other techniques. Analyses of the results show that the technique allows measurement of thermal diffusivity of coatings and films with uncertainties better than ±2.5%.

  17. Crystal surface integrity and diffusion measurements on Earth and planetary materials

    Science.gov (United States)

    Watson, E. B.; Cherniak, D. J.; Thomas, J. B.; Hanchar, J. M.; Wirth, R.

    2016-09-01

    Characterization of diffusion behavior in minerals is key to providing quantitative constraints on the ages and thermal histories of Earth and planetary materials. Laboratory experiments are a vital source of the needed diffusion measurements, but these can pose challenges because the length scales of diffusion achievable in a laboratory time are commonly less than 1 μm. An effective strategy for dealing with this challenge is to conduct experiments involving inward diffusion of the element of interest from a surface source, followed by quantification of the resulting diffusive-uptake profile using a high-resolution depth-profiling technique such as Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), or ion microprobe (SIMS). The value of data from such experiments is crucially dependent on the assumption that diffusion in the near-surface of the sample is representative of diffusion in the bulk material. Historical arguments suggest that the very process of preparing a polished surface for diffusion studies introduces defects-in the form of dislocations and cracks-in the outermost micrometer of the sample that make this region fundamentally different from the bulk crystal in terms of its diffusion properties. Extensive indirect evidence suggests that, in fact, the near-surface region of carefully prepared samples is no different from the bulk crystal in terms of its diffusion properties. A direct confirmation of this conclusion is nevertheless clearly important. Here we use transmission electron microscopy to confirm that the near-surface regions of olivine, quartz and feldspar crystals prepared using careful polishing protocols contain no features that could plausibly affect diffusion. This finding does not preclude damage to the mineral structure from other techniques used in diffusion studies (e.g., ion implantation), but even in this case the role of possible structural damage can be objectively assessed and controlled. While all

  18. Macromolecular Crowding Studies of Amino Acids Using NMR Diffusion Measurements and Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Amninder S Virk

    2015-02-01

    Full Text Available Molecular crowding occurs when the total concentration of macromolecular species in a solution is so high that a considerable proportion of the volume is physically occupied and therefore not accessible to other molecules. This results in significant changes in the solution properties of the molecules in such systems. Macromolecular crowding is ubiquitous in biological systems due to the generally high intracellular protein concentrations. The major hindrance to understanding crowding is the lack of direct comparison of experimental data with theoretical or simulated data. Self-diffusion is sensitive to changes in the molecular weight and shape of the diffusing species, and the available diffusion space (i.e., diffusive obstruction. Consequently, diffusion measurements are a direct means for probing crowded systems including the self-association of molecules. In this work, nuclear magnetic resonance measurements of the self-diffusion of four amino acids (glycine, alanine, valine and phenylalanine up to their solubility limit in water were compared directly with molecular dynamics simulations. The experimental data were then analyzed using various models of aggregation and obstruction. Both experimental and simulated data revealed that the diffusion of both water and the amino acids were sensitive to the amino acid concentration. The direct comparison of the simulated and experimental data afforded greater insights into the aggregation and obstruction properties of each amino acid.

  19. Development of Reference Materials for Thermal-Diffusivity Measurements by the Flash Method

    Science.gov (United States)

    Akoshima, M.; Abe, H.; Baba, T.

    2015-12-01

    The thermal conductivity of solid materials used for thermal simulations and thermal designs can be obtained as the product of thermal diffusivity, specific heat capacity, and bulk density in many cases. The thermal diffusivity is usually measured by the flash method, and the specific heat capacity is usually measured by differential scanning calorimetry. In order to obtain reliable thermal conductivities for strict thermal design, it is necessary to measure the thermal diffusivity using the flash method, a well-validated apparatus. Reference materials are an effective means for validation of most practical measurement apparatus. For the flash method, isotropic graphite was selected as a candidate reference material. A batch of isotropic graphite samples was prepared and characterized in detail in order to be a certified reference material for thermal-diffusivity measurement. The detailed characterization ensures the traceability of the measurement results to the international system of units (SI). A convenient reference material for thermal conductivity was also obtained by using the known thermal-diffusivity measurements, specific heat capacity, and density of the material.

  20. Measurement of diffuse and specular reflections through single cell layers

    CSIR Research Space (South Africa)

    Karsten, AE

    2006-07-01

    Full Text Available Reflections Through Single Cell Layers Presented at SAIP July 2006 Aletta E Karsten, J S Dam, A Singh National Laser Center 7 July 2006 Slide 2 © CSIR 2006 www.csir.co.za Outline • Background Why a Biophotonics group...532 Biomedical Optics ©1998 Steven L. Jacques, Scott A. Prahl, Oregon Graduate Institute Human tissue is considered a highly scattering media Slide 12 S a m p l e S a m p l e Integrating Sphere measurementsMeasurements of the total...

  1. Kurtosis of room impulse responses as a diffuseness measure for reverberation chambers

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    This study presents a kurtosis analysis of room impulse responses as a potential room diffuseness measure. The early part of an impulse response contains a direct sound and strong reflections. As these reflections are sparse and strong, the sound field is unlikely to be diffuse. Such deterministic...... reflections are extreme events, which prevent the pressure samples from being distributed Gaussianly, leading to a high kurtosis. This indicates that the kurtosis can be used as a diffuseness measure. Two rooms are analyzed. A non-uniform surface absorption distribution tends to increase the kurtosis...... significantly in a small room. A full scale reverberation chamber is tested with different diffuser settings, which shows that the kurtosis calculated from broadband impulse responses from 125 Hz to 4 kHz has a good correlation with the Sabine absorption coefficient according to ISO 354 (International...

  2. Field intercomparison of diffusive samplers for measuring ammonia.

    Science.gov (United States)

    Kirchner, M; Braeutigam, S; Ferm, M; Haas, M; Hangartner, M; Hofschreuder, P; Kasper-Giebl, A; Römmelt, H; Striedner, J; Terzer, W; Thöni, L; Werner, H; Zimmerling, R

    1999-06-01

    Agricultural production systems are recognised as a major source of atmospheric ammonia. Deposition of ammonia and ammonium may contribute to undesired changes in oligotrophic ecosystems. The continuous measurement of atmospheric ammonia requires expensive and sophisticated techniques and is performed only in a very restrict number of ambient air stations in Europe. Therefore, the application of passive samplers, which have the advantage of being easy to handle and cost-efficient, is useful. In the past the comparability of different passive samplers must be considered as rather scarce. In a joint European project under the leadership of the GSF-Forschungszentrum für Umwelt und Gesundheit, Neuherberg, in 1997 a comparison of different passive ammonia monitoring methods was carried out in a prealpine rural site near Garmisch-Partenkirchen. It was considered valuable to include not only well established systems but also methods still being developed. For the comparative test ten working groups with different methods took part. A wet annular denuder system, which has been developed by the Netherlands Energy Research Foundation for on-line measurement of atmospheric ammonia, served as reference of passive methods. The experiment, which started in June and finished in December, showed that most of the passive samplers fulfil the requirements and can be recommended for further measurements. Additional measurements of meteorological parameters were performed to check the influences of different weather conditions on passive sampling.

  3. Probe pressure effects on human skin diffuse reflectance and fluorescence spectroscopy measurements

    OpenAIRE

    Lim, Liang; Nichols, Brandon; Rajaram, Narasimhan; Tunnell, James W.

    2011-01-01

    Diffuse reflectance and fluorescence spectroscopy are popular research techniques for noninvasive disease diagnostics. Most systems include an optical fiber probe that transmits and collects optical spectra in contact with the suspected lesion. The purpose of this study is to investigate probe pressure effects on human skin spectroscopic measurements. We conduct an in-vivo experiment on human skin tissue to study the short-term (30 s) effects of probe pressure on diffuse reflectance and fluor...

  4. Effect of head impacts on diffusivity measures in a cohort of collegiate contact sport athletes.

    Science.gov (United States)

    McAllister, Thomas W; Ford, James C; Flashman, Laura A; Maerlender, Arthur; Greenwald, Richard M; Beckwith, Jonathan G; Bolander, Richard P; Tosteson, Tor D; Turco, John H; Raman, Rema; Jain, Sonia

    2014-01-07

    To determine whether exposure to repetitive head impacts over a single season affects white matter diffusion measures in collegiate contact sport athletes. A prospective cohort study at a Division I NCAA athletic program of 80 nonconcussed varsity football and ice hockey players who wore instrumented helmets that recorded the acceleration-time history of the head following impact, and 79 non-contact sport athletes. Assessment occurred preseason and shortly after the season with diffusion tensor imaging and neurocognitive measures. There was a significant (p = 0.011) athlete-group difference for mean diffusivity (MD) in the corpus callosum. Postseason fractional anisotropy (FA) differed (p = 0.001) in the amygdala (0.238 vs 0.233). Measures of head impact exposure correlated with white matter diffusivity measures in several brain regions, including the corpus callosum, amygdala, cerebellar white matter, hippocampus, and thalamus. The magnitude of change in corpus callosum MD postseason was associated with poorer performance on a measure of verbal learning and memory. This study suggests a relationship between head impact exposure, white matter diffusion measures, and cognition over the course of a single season, even in the absence of diagnosed concussion, in a cohort of college athletes. Further work is needed to assess whether such effects are short term or persistent.

  5. Voltammetric measurement of ultraslow diffusion rates in polymeric media with microdisk electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Longmire, M.L.; Watanabe, M.; Zhang, H.; Wooster, T.T.; Murray, R.W. (Univ. of North Carolina, Chapel Hill (USA))

    1990-04-01

    Cyclic voltammetry and chronoamperometry were used in conjunction with microdisk electrodes in polymeric solvents to measure diffusion coefficients of ferrocene redox solutes down to 10{sup {minus}12} cm{sup 2}/s. Experimental manipulation of the parameter {tau} ({tau} = 4Dt/r{sup 2}) results in diffusion profiles dominated by radial diffusion, linear diffusion, or a combination of the two. In the former two cases, adherence to the steady-state current equation for a a microdisk and the Cottrell equation, respectively, was observed. Under conditions of mixed contribution, evaluation of diffusion coefficients was based on comparison of experimental and simulated current-time curves. Generally, diffusion coefficients >10{sup {minus}7} cm{sup 2}/s were evaluated from steady-state potential sweeps. Diffusion coefficients <10{sup {minus}11} cm{sup 2}/s could be evaluated by a standard Cottrell analysis. Values in the transition region were evaluated from the slope of nonzero intercept Cottrell plots. A numerical guideline, based on {tau}, is presented.

  6. PIV measurements in a compact return diffuser under multi-conditions

    Science.gov (United States)

    Zhou, L.; Lu, W. G.; Shi, W. D.

    2013-12-01

    Due to the complex three-dimensional geometries of impellers and diffusers, their design is a delicate and difficult task. Slight change could lead to significant changes in hydraulic performance and internal flow structure. Conversely, the grasp of the pump's internal flow pattern could benefit from pump design improvement. The internal flow fields in a compact return diffuser have been investigated experimentally under multi-conditions. A special Particle Image Velocimetry (PIV) test rig is designed, and the two-dimensional PIV measurements are successfully conducted in the diffuser mid-plane to capture the complex flow patterns. The analysis of the obtained results has been focused on the flow structure in diffuser, especially under part-load conditions. The vortex and recirculation flow patterns in diffuser are captured and analysed accordingly. Strong flow separation and back flow appeared at the part-load flow rates. Under the design and over-load conditions, the flow fields in diffuser are uniform, and the flow separation and back flow appear at the part-load flow rates, strong back flow is captured at one diffuser passage under 0.2Qdes.

  7. Multiplexed measurement of protein diffusion in Caenorhabditis elegans embryos with SPIM-FCS

    Science.gov (United States)

    Struntz, Philipp; Weiss, Matthias

    2016-02-01

    Quantifying the diffusion behavior of proteins in different environments, e.g. on cellular membranes, is a key step in uncovering the vital action of protein networks in living organisms. While several established techniques for local diffusion measurements exist, the life sciences are currently in need of a multiplexed, i.e. spatially parallelized, data acquisition that allows for obtaining diffusion maps with high spatiotemporal resolution. Following this demand, the combination of camera-based single-plane illumination microscopy (SPIM) and fluorescence correlation spectroscopy (FCS) has recently emerged as a promising approach. So far, SPIM-FCS has mainly been used to assess the diffusion of soluble particles and proteins in vitro and in culture cells, but due to a particularly low photobleaching and -toxicity the method is also well applicable to developmental organisms. Here, we have probed the performance of SPIM-FCS on an established developmental model organism, the small nematode Caenorhabditis elegans. In particular, we have quantified the diffusion of the peripheral membrane protein PLC1δ 1 in the embryo’s cytoplasm and on the plasma membrane. As a result, we were able to derive diffusion maps of PLC1δ 1 in both compartments in multiple individuals, showing the spatially varying diffusion coefficients across the embryo. Our data also report on the dissociation kinetics of PLC1δ 1 from the plasma membrane, hence underlining that SPIM-FCS can be used to explore key features of peripheral membrane proteins in fragile developmental model organisms.

  8. Measurement of heat and momentum eddy diffusivities in recirculating LMFBR outlet plenum flows

    Energy Technology Data Exchange (ETDEWEB)

    Manno, V.P.; Golay, M.W.

    1978-06-01

    An optical technique has been developed for the measurement of the eddy diffusivity of heat in a transparent flowing medium. The method uses a combination of two established measurement tools: a Mach-Zehnder interferometer for the monitoring of turbulently fluctuating temperature and a Laser Doppler Anemometer (LDA) for the measurement of turbulent velocity fluctuations. The technique is applied to the investigation of flow fields characteristic of the LMFBR outlet plenum. The study is accomplished using air as the working fluid in a small scale Plexiglas test section. Lows are introduced into both the /sup 1///sub 15/ scale FFTF outlet plenum and the /sup 3///sub 80/ scale CRBR geometry plenum at inlet Reynolds numbers of 22,000. Measurements of the eddy diffusivity of heat and the eddy diffusivity of momentum are performed at a total of 11 measurement stations. Significant differences of the turbulence parameters are found between the two geometries, and the higher chimney structure of the CRBR case is found to be the major cause of the distinction. Spectral intensity studies of the fluctuating electronic analog signals of velocity and temperature are also performed. Error analysis of the overall technique indicates an experimental error of 10% in the determination of the eddy diffusivity of heat and 6% in the evaluation of turbulent momentum viscosity. In general it is seen that the turbulence in the cases observed is not isotropic, and use of isotropic turbulent heat and momentum diffusivities in transport modelling would not be a valid procedure.

  9. Mapping measures of microscopic diffusion anisotropy in human brain white matter in vivo with double-wave-vector diffusion-weighted imaging.

    Science.gov (United States)

    Lawrenz, Marco; Finsterbusch, Jürgen

    2015-02-01

    To demonstrate that rotationally invariant measures of the diffusion anisotropy on a microscopic scale can be mapped in human brain white matter in vivo. Echo-planar imaging experiments (resolution 3.0 × 3.0 × 3.0 mm(3) ) involving two diffusion-weighting periods (δ = 22 ms, Δ = 25 ms) in the same acquisition, so-called double-wave-vector or double-pulsed-field-gradient diffusion-weighting experiments, were performed on a 3 T whole-body magnetic resonance system with a long mixing time ( τm=45 ms) between the two diffusion weightings. The disturbing influences of background gradient fields, eddy currents, and the finite mixing time can be minimized using 84 direction combinations based on nine directions and their antipodes. In healthy volunteers, measures of the microscopic diffusion anisotropy ( IMA and MA indexes) could be mapped in white matter across the human brain. The measures were independent (i) of the absolute orientation of the head and of the diffusion directions and (ii) of the predominant fiber orientation. Compared to the fractional anisotropy derived from the conventional diffusion tensor, the double-wave-vector indexes exhibit a narrower distribution, which could reflect their independence of the fiber orientation distribution. Mapping measures of the microscopic diffusion anisotropy in human brain white matter is feasible in vivo and could help to characterize tissue microstructure in the healthy and pathological brain. © 2014 Wiley Periodicals, Inc.

  10. CONSEQUENCES OF USING HOME-MADE RADON SOURCES FOR MEASURING THE RADON DIFFUSION COEFFICIENT.

    Science.gov (United States)

    Dobrovolný, T; Jiránek, M

    2017-11-01

    The applicability of home-made radon sources for determining the radon diffusion coefficient of waterproofing materials was studied for three representatives of materials with a high radium content: uraninite, slag concrete and filter sand. The results of our investigation confirmed that the radon production rate of home-made radon sources is significantly lower than the radon production rate of artificial sources. Consequently, home-made sources are usually unable to generate concentrations higher than 100 kBq/m3 in the source container. Therefore, they cannot be used for determining radon diffusion coefficients lower than 1 × 10-12 m2/s. In addition, when home-made radon sources are used, only time-dependent mathematical solutions of the non-stationary radon diffusion can be used for determining the radon diffusion coefficient from the measured data. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Additive inhibition of complement deposition by pneumolysin and PspA facilitates Streptococcus pneumoniae septicemia.

    Science.gov (United States)

    Yuste, Jose; Botto, Marina; Paton, James C; Holden, David W; Brown, Jeremy S

    2005-08-01

    Streptococcus pneumoniae is a common cause of septicemia in the immunocompetent host. To establish infection, S. pneumoniae has to overcome host innate immune responses, one component of which is the complement system. Using isogenic bacterial mutant strains and complement-deficient immune naive mice, we show that the S. pneumoniae virulence factor pneumolysin prevents complement deposition on S. pneumoniae, mainly through effects on the classical pathway. In addition, using a double pspA-/ply- mutant strain we demonstrate that pneumolysin and the S. pneumoniae surface protein PspA act in concert to affect both classical and alternative complement pathway activity. As a result, the virulence of the pspA-/ply- strain in models of both systemic and pulmonary infection is greatly attenuated in wild-type mice but not complement deficient mice. The sensitivity of the pspA-/ply- strain to complement was exploited to demonstrate that although early innate immunity to S. pneumoniae during pulmonary infection is partially complement-dependent, the main effect of complement is to prevent spread of S. pneumoniae from the lungs to the blood. These data suggest that inhibition of complement deposition on S. pneumoniae by pneumolysin and PspA is essential for S. pneumoniae to successfully cause septicemia. Targeting mechanisms of complement inhibition could be an effective therapeutic strategy for patients with septicemia due to S. pneumoniae or other bacterial pathogens.

  12. Heterologous expression of pneumococcal virulence factor PspC on the surface of Lactococcus lactis confers adhesive properties.

    Science.gov (United States)

    Asmat, Tauseef M; Klingbeil, Katharina; Jensch, Inga; Burchhardt, Gerhard; Hammerschmidt, Sven

    2012-03-01

    Lactococcus lactis is a non-pathogenic bacterium that is used in the food industry but is also used as a heterologous host to reveal protein functions of pathogenic bacteria. The adhesin PspC from Streptococcus pneumoniae is a choline-binding protein that is non-covalently anchored to the bacterial cell wall. To assess the exclusive impact of pneumococcal surface protein C (PspC) on the interplay with its host we generated recombinant L. lactis producing a nisin-inducible and covalently anchored variant of PspC on the lactococcal cell surface. A translational fusion of the 5'-end of pspC3.4 with the 3'-end of hic (pspC11.4) was designed to decorate the surface of L. lactis with a chimeric PspC. The PspC3.4 part comprises the first 281 aa residues of PspC3.4, while the Hic sequence consists of the proline-rich and sortase-anchored domain. The results demonstrated that PspC is sufficient for adhesion and subsequent invasion of host epithelial cells expressing the human polymeric Ig receptor (hpIgR). Moreover, invasion via hpIgR was even more pronounced when the chimeric PspC was produced by lactococci compared with pneumococci. This study shows also for the first time that PspC plays no significant role during phagocytosis by macrophages. In contrast, recruitment of Factor H via the PspC chimer has a dramatic effect on phagocytosis of recombinant but not wild-type lactococci, as Factor H interacts specifically with the amino-terminal part of PspC and mediates the contact with phagocytes. Furthermore, L. lactis expressing PspC increased intracellular calcium levels in pIgR-expressing epithelial cells, thus resembling the effect of pneumococci, which induced release of Ca(2+) from intracellular stores via the PspC-pIgR mechanism. In conclusion, expression of the chimeric PspC confers adhesive properties to L. lactis and indicates the potential of L. lactis as a suitable host to study the impact of individual bacterial factors on their capacity to interfere with the

  13. PSP-SOI: An advanced surface potential based compact model of partially depleted SOI MOSFETs for circuit simulations

    Science.gov (United States)

    Wu, W.; Li, X.; Gildenblat, G.; Workman, G. O.; Veeraraghavan, S.; McAndrew, C. C.; van Langevelde, R.; Smit, G. D. J.; Scholten, A. J.; Klaassen, D. B. M.; Watts, J.

    2009-01-01

    This paper reports recent progress in partially depleted (PD) SOI MOSFET modeling using a surface potential based approach. The new model is formulated within the framework of the latest industry standard bulk MOSFET model PSP. In addition to its physics-based formulation and scalability inherited from PSP, PSP-SOI captures SOI specific effects by including floating body simulation capability, parasitic body currents and capacitances. A nonlinear body resistance model is included for accurate characterization and simulation of body-contacted SOI devices. The PSP-SOI model has been verified using test data from 90 nm to 65 nm PD/SOI processes.

  14. Diffusion measurement of intraplaque hemorrhage and intramural hematoma using diffusion weighted MRI at 3T in cervical artery

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Bin [The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi (China); Yang, Li [Fudan University, Department of Radiology, Shanghai Institute of Medical Imaging, Zhongshan Hospital, Shanghai (China); Wang, Guangbin; Shi, Honglu; Wang, Shanshan; Li, Huihua [Shandong University, Shandong Medical Imaging Research Institute, Jinan, Shandong (China); Chen, Weibo; Chan, Queenie [Philips Healthcare, Shanghai (China)

    2016-10-15

    To assess the difference between carotid haemorrhagic plaque and non-haemorrhagic plaque by using diffusion-weighted imaging (DWI) and to evaluate carotid intraplaque haemorrhage (IPH) and intramural hematoma (IMH) of cervical artery dissection with apparent diffusion coefficient (ADC) measurement. Fifty-one symptomatic patients underwent 3.0-T carotid MR imaging, including conventional sequences, three-dimensional (3D) magnetization-prepared rapid acquisition gradient-echo (MPRAGE) sequence, and DWI. Thirty-nine patients with carotid plaque and eight patients with IMH of cervical artery dissection were finally included. The groups of hemorrhagic plaque, non-hemorrhagic plaque and IMH were divided according to 3D MPRAGE sequence. ADC values of different groups were measured, and t tests were performed. The mean ADC values of hemorrhagic plaques, non-hemorrhagic plaque and IMH were (1.284 ± 0.327) x 10{sup -3}mm{sup 2}/s, (1.766 ± 0.477) x 10{sup -3}mm{sup 2}/s, and (0.563 ± 0.119) x 10{sup -3}mm{sup 2}/s, respectively. The mean ADC values of hemorrhagic and non-hemorrhagic regions in the hemorrhagic plaque group were (0.985 ± 0.376) x 10{sup -3}mm{sup 2}/s and (1.480 ± 0.465) x 10{sup -3}mm{sup 2}/s, respectively. The differences between the hemorrhagic plaque and non-hemorrhagic plaque, hemorrhagic region and non-hemorrhagic region in hemorrhagic plaque, and the hemorrhagic region in the hemorrhagic plaque and IMH of artery dissection were significant (P < 0.05). DWI may be a useful complement to conventional MR imaging for identifying haemorrhage of carotid plaques and differentiate IMHs from IPH. (orig.)

  15. Measurement of the Thermal Diffusivity of GaAs by Pulsed Photothermal Spectroscopy

    Science.gov (United States)

    Bennis, G. L.; Vyas, Reeta; Gupta, R.; Ang, S.; Brown, W. D.

    1997-03-01

    Pulsed photothermal spectroscopy has been used to measure thermal diffusivity of GaAs. In this technique, a short pulse of radiation from a Ti-Sapphire laser is used to produce local heating on a sample of GaAs wafer. The heating of the sample is monitored by deflection of a weak cw laser beam (probe beam). The thermal diffusivity of the sample is deduced from the time evolution of the deflection of the probe beam. Results of the latest measurements will be presented.

  16. Measurement of the diffusion coefficient of oriented Na atoms in different buffer gases

    Energy Technology Data Exchange (ETDEWEB)

    Bicchi, P. (Siena Univ. (Italy). Ist. di Fisica); Moi, L.; Savino, P.; Zambon, B. (Consiglio Nazionale delle Ricerche, Pisa (Italy). Lab. di Fisica Atomica e Moleculare)

    1980-01-11

    The authors report the measurements of the diffusion coefficients of Na in different buffer gases obtained through the study of the optical activity of Na vapour oriented by laser light. The reliability of this method is analyzed in the different physical situations to which the different buffer gases give rise. The accuracy of the method, in all cases in which extremely short relaxation processes are absent, is confirmed either by the comparison among the diffusion coefficient values here measured and those present in the literature obtained with different techniques, or by the analysis of the polarization distribution in steady conditions, which results to be in good agreement with the theoretical forecasts.

  17. Non-invasive measurements of tissue hemodynamics with hybrid diffuse optical methods

    Science.gov (United States)

    Durduran, Turgut

    Diffuse optical techniques were used to measure hemodynamics of tissues non-invasively. Spectroscopy and tomography of the brain, muscle and implanted tumors were carried out in animal models and humans. Two qualitatively different methods, diffuse optical tomography and diffuse correlation tomography, were hybridized permitting simultaneous measurement of total hemoglobin concentration, blood oxygen saturation and blood flow. This combination of information was processed further to derive estimates of oxygen metabolism (e.g. CMRO 2) in tissue. The diffuse correlation measurements of blood flow were demonstrated in human tissues, for the first time, demonstrating continous, non-invasive imaging of oxygen metabolism in large tissue volumes several centimeters below the tissue surface. The bulk of these investigations focussed on cerebral hemodynamics. Extensive validation of this methodology was carried out in in vivo rat brain models. Three dimensional images of deep tissue hemodynamics in middle cerebral artery occlusion and cortical spreading depression (CSD) were obtained. CSD hemodynamics were found to depend strongly on partial pressure of carbon dioxide. The technique was then adapted for measurement of human brain. All optical spectroscopic measurements of CMRO2 during functional activation were obtained through intact human skull non-invasively. Finally, a high spatio-temporal resolution measurement of cerebral blood flow due to somatosensory cortex activation following electrical forepaw stimulation in rats was carried out with laser speckle flowmetry. New analysis methods were introduced for laser speckle flowmetry. In other organs, deep tissue hemodynamics were measured on human calf muscle during exercise and cuff-ischemia and were shown to have some clinical utility for peripheral vascular disease. In mice tumor models, the measured hemodynamics were shown to be predictive of photodynamic therapy efficacy, again suggesting promise of clinical utility

  18. Diffusion voltage in polymer light emitting diodes measured with electric field induced second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, P.K.; Rafaelsen, J.; Pedersen, T.G.; Pedersen, K. [Department of Physics and Nanotechnology, Aalborg University, Pontoppidanstraede 103, 9220 Aalborg East (Denmark)

    2005-12-01

    We apply electric field induced second harmonic (EFISH) to polymer light emitting diodes (PLEDs) and demonstrate the ability to determine the diffusion voltage in PLED devices. The EFISH signal is proportional to the square of the effective field, which is the sum of the diffusion voltage and the applied voltage. By minimizing the EFISH-signal as a function of the applied voltage, the diffusion voltage is determined by measuring the applied voltage that cancels out the diffusion voltage. The PLEDs are fabricated with indium tin oxide (ITO) as the hole injecting contact and two different electron injecting contacts, namely aluminum and calcium. The diffusion voltage originates from the rearranged charges caused by the difference in Fermi levels in the materials in the PLEDs. Different contacts will thus cause different diffusion voltages. We demonstrate here that the EFISH signal is proportional to the square of the effective field in both reverse and forward bias, and discuss the dependence on contact materials. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Reproducibility and Variation of Diffusion Measures in the Squirrel Monkey Brain, In Vivo and Ex Vivo

    Science.gov (United States)

    Schilling, Kurt; Gao, Yurui; Stepniewska, Iwona; Choe, Ann S; Landman, Bennett A; Anderson, Adam W

    2016-01-01

    Purpose Animal models are needed to better understand the relationship between diffusion MRI (dMRI) and the underlying tissue microstructure. One promising model for validation studies is the common squirrel monkey, Saimiri sciureus. This study aims to determine (1) the reproducibility of in vivo diffusion measures both within and between subjects; (2) the agreement between in vivo and ex vivo data acquired from the same specimen and (3) normal diffusion values and their variation across brain regions. Methods Data were acquired from three healthy squirrel monkeys, each imaged twice in vivo and once ex vivo. Reproducibility of fractional anisotropy (FA), mean diffusivity (MD), and principal eigenvector (PEV) was assessed, and normal values were determined both in vivo and ex vivo. Results The calculated coefficients of variation (CVs) for both intra-subject and inter-subject MD were below 10% (low variability) while FA had a wider range of CVs, 2–14% intra-subject (moderate variability), and 3–31% inter-subject (high variability). MD in ex vivo tissue was lower than in vivo (30%–50% decrease), while FA values increased in all regions (30–39% increase). The mode of angular differences between in vivo and ex vivo PEVs was 12 degrees. Conclusion This study characterizes the diffusion properties of the squirrel monkey brain and serves as the groundwork for using the squirrel monkey, both in vivo and ex vivo, as a model for diffusion MRI studies. PMID:27587226

  20. Nuclear magnetic resonance relaxation and diffusion measurements as a proxy for soil properties

    Science.gov (United States)

    Duschl, Markus; Pohlmeier, Andreas; Galvosas, Petrik; Vereecken, Harry

    2013-04-01

    Nuclear Magnetic Resonance (NMR) relaxation and NMR diffusion measurements are two of a series of fast and non-invasive NMR applications widely used e.g. as well logging tools in petroleum exploration [1]. For experiments with water, NMR relaxation measures the relaxation behaviour of former excited water molecules, and NMR diffusion evaluates the self-diffusion of water. Applied in porous media, both relaxation and diffusion measurements depend on intrinsic properties of the media like pore size distribution, connectivity and tortuosity of the pores, and water saturation [2, 3]. Thus, NMR can be used to characterise the pore space of porous media not only in consolidated sediments but also in soil. The physical principle behind is the relaxation of water molecules in an external magnetic field after excitation. In porous media water molecules in a surface layer of the pores relax faster than the molecules in bulk water because of interactions with the pore wall. Thus, the relaxation in smaller pores is generally faster than in bigger pores resulting in a relaxation time distribution for porous media with a range of pore sizes like soil [4]. In NMR diffusion experiments, there is an additional encoding of water molecules by application of a magnetic field gradient. Subsequent storage of the magnetization and decoding enables the determination of the mean square displacement and therefore of the self-diffusion of the water molecules [5]. Employing various relaxation and diffusion experiments, we get a measure of the surface to volume ratio of the pores and the tortuosity of the media. In this work, we show the characterisation of a set of sand and soil samples covering a wide range of textural classes by NMR methods. Relaxation times were monitored by the Carr-Purcell-Meiboom-Gill sequence and analysed using inverse Laplace transformation. Apparent self-diffusion constants were detected by a 13-intervall pulse sequence and variation of the storage time. We

  1. Using a simple apparatus to measure direct and diffuse photosynthetically active radiation at remote locations.

    Directory of Open Access Journals (Sweden)

    Michael J Cruse

    Full Text Available Plant canopy interception of photosynthetically active radiation (PAR drives carbon dioxide (CO2, water and energy cycling in the soil-plant-atmosphere system. Quantifying intercepted PAR requires accurate measurements of total incident PAR above canopies and direct beam and diffuse PAR components. While some regional data sets include these data, e.g. from Atmospheric Radiation Measurement (ARM Program sites, they are not often applicable to local research sites because of the variable nature (spatial and temporal of environmental variables that influence incoming PAR. Currently available instrumentation that measures diffuse and direct beam radiation separately can be cost prohibitive and require frequent adjustments. Alternatively, generalized empirical relationships that relate atmospheric variables and radiation components can be used but require assumptions that increase the potential for error. Our goal here was to construct and test a cheaper, highly portable instrument alternative that could be used at remote field sites to measure total, diffuse and direct beam PAR for extended time periods without supervision. The apparatus tested here uses a fabricated, solar powered rotating shadowband and other commercially available parts to collect continuous hourly PAR data. Measurements of total incident PAR had nearly a one-to-one relationship with total incident radiation measurements taken at the same research site by an unobstructed point quantum sensor. Additionally, measurements of diffuse PAR compared favorably with modeled estimates from previously published data, but displayed significant differences that were attributed to the important influence of rapidly changing local environmental conditions. The cost of the system is about 50% less than comparable commercially available systems that require periodic, but not continual adjustments. Overall, the data produced using this apparatus indicates that this instrumentation has the

  2. A modified version of the combined in-diffusion/abrasive peeling technique for measuring diffusion of strongly sorbing radionuclides in argillaceous rocks: a test study on the diffusion of caesium in Opalinus Clay.

    Science.gov (United States)

    Van Loon, Luc R; Müller, Werner

    2014-08-01

    A filter free diffusion set-up was developed for measuring the diffusion of strongly sorbing radionuclides in indurated argillaceous rocks such as Opalinus Clay (OPA) that normally disintegrate when contacted with a solution. Small bore cores drilled parallel to the bedding plane and embedded in epoxy resin were found to be stable and could be used for performing in-diffusion measurements. The method was tested with the diffusion of caesium, spiked with caesium-134, in Opalinus Clay. The profile of Cs in the clay sample was determined with a modified version of the abrasive peeling technique. The diffusion parameters obtained for caesium were in fair agreement with those determined earlier using the classical through-diffusion technique where stainless steel filters were used to confine the samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. A transient divided-bar method for simultaneous measurements of thermal conductivity and thermal diffusivity

    DEFF Research Database (Denmark)

    Bording, Thue Sylvester; Nielsen, Søren Bom; Balling, Niels

    2016-01-01

    Accurate information on thermal conductivity and thermal diffusivity of materials is of central importance in relation to geoscience and engineering problems involving the transfer of heat. Within the geosciences, this applies to all aspects regarding the determination of terrestrial heat flow...... and subsurface temperature modelling. Several methods, including the classical divided-bar technique, are available for laboratory measurements of thermal conductivity, and much fewer for thermal diffusivity. We have generalized the divided-bar technique to the transient case, in which thermal conductivity...... and volumetric heat capacity, and thereby also thermal diffusivity, are measured simultaneously. As the density of samples is easily determined independently, specific heat capacity may also be determined. Finite element formulation provides a flexible forward solution for heat transfer across the bar...

  4. Electroluminescence pulse shape and electron diffusion in liquid argon measured in a dual-phase TPC

    Energy Technology Data Exchange (ETDEWEB)

    Agnes, P.; et al.

    2018-02-05

    We report the measurement of the longitudinal diffusion constant in liquid argon with the DarkSide-50 dual-phase time projection chamber. The measurement is performed at drift electric fields of 100 V/cm, 150 V/cm, and 200 V/cm using high statistics $^{39}$Ar decays from atmospheric argon. We derive an expression to describe the pulse shape of the electroluminescence signal (S2) in dual-phase TPCs. The derived S2 pulse shape is fit to events from the uppermost portion of the TPC in order to characterize the radial dependence of the signal. The results are provided as inputs to the measurement of the longitudinal diffusion constant DL, which we find to be (4.12 $\\pm$ 0.04) cm$^2$/s for a selection of 140keV electron recoil events in 200V/cm drift field and 2.8kV/cm extraction field. To study the systematics of our measurement we examine datasets of varying event energy, field strength, and detector volume yielding a weighted average value for the diffusion constant of (4.09 $\\pm$ 0.09) cm$^2$ /s. The measured longitudinal diffusion constant is observed to have an energy dependence, and within the studied energy range the result is systematically lower than other results in the literature.

  5. Measurement of Rapid Protein Diffusion in the Cytoplasm by Photo-Converted Intensity Profile Expansion

    Directory of Open Access Journals (Sweden)

    Rotem Gura Sadovsky

    2017-03-01

    Full Text Available The fluorescence microscopy methods presently used to characterize protein motion in cells infer protein motion from indirect observables, rather than measuring protein motion directly. Operationalizing these methods requires expertise that can constitute a barrier to their broad utilization. Here, we have developed PIPE (photo-converted intensity profile expansion to directly measure the motion of tagged proteins and quantify it using an effective diffusion coefficient. PIPE works by pulsing photo-convertible fluorescent proteins, generating a peaked fluorescence signal at the pulsed region, and analyzing the spatial expansion of the signal. We demonstrate PIPE’s success in measuring accurate diffusion coefficients in silico and in vitro and compare effective diffusion coefficients of native cellular proteins and free fluorophores in vivo. We apply PIPE to measure diffusion anomality in the cell and use it to distinguish free fluorophores from native cellular proteins. PIPE’s direct measurement and ease of use make it appealing for cell biologists.

  6. Increased self-diffusion of brain water in hydrocephalus measured by MR imaging

    DEFF Research Database (Denmark)

    Gideon, P; Thomsen, C; Gjerris, F

    1994-01-01

    We used MR imaging to measure the apparent brain water self-diffusion in 5 patients with normal pressure hydrocephalus (NPH), in 2 patients with high pressure hydrocephalus (HPH), and in 8 age-matched controls. In all patients with NPH significant elevations of the apparent diffusion coefficients...... brain water fraction. For further studies of brain water diffusion in hydrocephalus patients, echo-planar imaging techniques with imaging times of a few seconds may be valuable.......We used MR imaging to measure the apparent brain water self-diffusion in 5 patients with normal pressure hydrocephalus (NPH), in 2 patients with high pressure hydrocephalus (HPH), and in 8 age-matched controls. In all patients with NPH significant elevations of the apparent diffusion coefficients...... (ADC) of brain water were found within periventricular white matter, in the corpus callosum, in the internal capsule, within cortical gray matter, and in cerebrospinal fluid, whereas normal ADCs were found within the basal ganglia. In 2 patients with HPH elevated ADCs were found most prominently within...

  7. A comparison of concentration measurement techniques for the estimation of the apparent mass diffusion coefficient

    Directory of Open Access Journals (Sweden)

    L.M. Pereira

    2001-09-01

    Full Text Available In this article we compare two different techniques to measure the concentration of saline solutions for the identification of the apparent mass diffusion coefficient in soils saturated with distilled water. They are the radiation measurement technique and the electrical conductivity measurement technique. These techniques are compared in terms of measured quantities, sensitivity coefficients with respect to unknown parameters and the determinant of the information matrix. The apparent mass diffusion coefficient is estimated by utilizing simulated measurements containing random errors. The Levenberg-Marquardt method of minimization of the least-squares norm is used as the parameter estimation procedure. The effects of the volume of saline solution injected into the column devised for the experiments on the accuracy of the estimated parameters are also addressed in this article.

  8. Lunar occultation of the diffuse radio sky: LOFAR measurements between 35 and 80 MHz

    NARCIS (Netherlands)

    Vedantham, H. K.; Koopmans, L. V. E.; de Bruyn, A. G.; Wijnholds, S. J.; Brentjens, M.; Abdalla, F. B.; Asad, K. M. B.; Bernardi, G.; Bus, S.; Chapman, E.; Ciardi, B.; Daiboo, S.; Fernandez, E. R.; Ghosh, A.; Harker, G.; Jelic, V.; Jensen, H.; Kazemi, S.; Lambropoulos, P.; Martinez-Rubi, O.; Mellema, G.; Mevius, M.; Offringa, A. R.; Pandey, V. N.; Patil, A. H.; Thomas, R. M.; Veligatla, V.; Yatawatta, S.; Zaroubi, S.; Anderson, J.; Asgekar, A.; Bell, M. E.; Bentum, M. J.; Best, P.; Bonafede, A.; Breitling, F.; Broderick, J.; Brüggen, M.; Butcher, H. R.; Corstanje, A.; de Gasperin, F.; de Geus, E.; Deller, A.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fallows, R. A.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; Hassall, T. E.; Heald, G.; Hoeft, M.; Hörandel, J.; Iacobelli, M.; Juette, E.; Kondratiev, V. I.; Kuniyoshi, M.; Kuper, G.; Mann, G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; McKean, J. P.; Mulcahy, D. D.; Munk, H.; Nelles, A.; Norden, M. J.; Orru, E.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Renting, A.; Röttgering, H.; Schwarz, D.; Shulevski, A.; Smirnov, O.; Stappers, B. W.; Steinmetz, M.; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Thoudam, S.; Toribio, C.; Vocks, C.; Wise, M. W.; Wucknitz, O.; Zarka, P.

    2015-01-01

    We present radio observations of the Moon between 35 and 80 MHz to demonstrate a novel technique of interferometrically measuring large-scale diffuse emission extending far beyond the primary beam (global signal) for the first time. In particular, we show that (i) the Moon appears as a negative-flux

  9. The use of simple diffusion tube samplers for the measurement of

    African Journals Online (AJOL)

    The use of simple diffusion tube samplers for the measurement of nitrogen dioxide in an operating room using nitrogen oxide as an anaesthetic (July — November 1999). *E. E. Ukpebor and C. 0. lmarengiaye. *Department Qf Chemistry and Department of/1 naesthesiology. University of Benin, Benin City, Nigeria. Summary.

  10. The use of simple diffusion tube samplers for the measurement of ...

    African Journals Online (AJOL)

    Estimates have been made of the amount of nitrogen dioxide (NO2) in the operating room of the university of Benin Teaching Hospital (UBTH) where nitrous oxide (N2O) a potential source of NO is used as an anaesthetic agent. Measurements were made using palmes diffusion tubes, a device which is capable of taking ...

  11. The use of simple diffusion tube samplers for the measurement of

    African Journals Online (AJOL)

    1999-11-01

    Nov 1, 1999 ... The use of simple diffusion tube samplers for the measurement of nitrogen dioxide in an operating room using nitrogen oxide as an anaesthetic (July —. November 1999). *E. E. Ukpebor and C. O. Imarengiaye. *Department of Chemistry and Department of A naesthesiology. University of Benin, Benin City, ...

  12. Fe and N diffusion in nitrogen-rich FeN measured using neutron ...

    Indian Academy of Sciences (India)

    Fe and N diffusion in nitrogen-rich FeN measured using neutron reflectometry. MUKUL GUPTA1,∗, A GUPTA2, A WILDES3 and T GUTBERLET4. 1UGC-DAE Consortium for Scientific Research, R-5 Shed, Bhabha Atomic Research. Centre, Mumbai 400 085, India. 2UGC-DAE Consortium for Scientific Research, Khandwa ...

  13. Derivation of Inter-Atomic Force Constants of Cu2O from Diffuse Neutron Scattering Measurement

    Directory of Open Access Journals (Sweden)

    T. Makhsun

    2013-04-01

    Full Text Available Neutron scattering intensity from Cu2O compound has been measured at 10 K and 295 K with High Resolution Powder Diffractometer at JRR-3 JAEA. The oscillatory diffuse scattering related to correlations among thermal displacements of atoms was observed at 295 K. The correlation parameters were determined from the observed diffuse scattering intensity at 10 and 295 K. The force constants between the neighboring atoms in Cu2O were estimated from the correlation parameters and compared to those of Ag2O

  14. Increased self-diffusion of brain water in hydrocephalus measured by MR imaging

    DEFF Research Database (Denmark)

    Gideon, P; Thomsen, C; Gjerris, F

    1994-01-01

    We used MR imaging to measure the apparent brain water self-diffusion in 5 patients with normal pressure hydrocephalus (NPH), in 2 patients with high pressure hydrocephalus (HPH), and in 8 age-matched controls. In all patients with NPH significant elevations of the apparent diffusion coefficients...... (ADC) of brain water were found within periventricular white matter, in the corpus callosum, in the internal capsule, within cortical gray matter, and in cerebrospinal fluid, whereas normal ADCs were found within the basal ganglia. In 2 patients with HPH elevated ADCs were found most prominently within...

  15. Measurement of pore diffusion in catalytic materials. Report 1997-07-01--1997-12-31

    Energy Technology Data Exchange (ETDEWEB)

    Papadias, Dennis; Barbesta, Fabio; Foresti, Laura; Thevenin, Philippe; Bjoernbom, Pehr; Jaeraas, Sven [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Technology

    2000-05-01

    This report covers the work during the period (97-07-01--97-12-31) of NUTEK project P10313-1 'Measurement of pore diffusion in catalytic materials'. The project was carried out at the Department of Chemical Engineering and Technology - Chemical Technology at Kungliga Tekniska Hoegskolan. The performance of heterogeneous catalysts is strongly dependent of the combined rate of pore diffusion and chemical reaction. In order to describe correctly the interactions between physical and chemical phenomena in porous media, it is necessary to know the effective values of the diffusion coefficients in the catalyst. Existing mathematical correlations of the diffusivity coefficients may give misleading results so there is a need to determine those values experimentally. Literature studies and previous work in this laboratory have shown that pulse chromatography is to prefer as a fast and reliable method to measure effective diffusivities. In this study, the pulse chromatographic technique was used to determine the effective diffusivity in commercial cylindrical ring-shaped catalysts in order to validate and further develop this technique. The pellets, approximately 5-mm long, were mounted axially side by side and a dense polymer was shrunk at the outer wall, fastening the catalyst particles in a column of arbitrary length and with a rigid structure. The value of the diffusivity coefficient was determined by matching the experimental response curve by the theoretical one, solved numerically in the time domain using the finite difference method. Two types of model equations relating the transport processes occurring in the column were derived. In both models the stationary phase was treated as homogeneous and the axial diffusion in it was neglected. The more rigorous, or two dimensional model, accounted for radial diffusion in the gas phase, while in the simpler, or one dimensional model, the solute in the gas phase was averaged in terms of a local mean concentration

  16. On-body calibration and measurements using personal radiofrequency exposimeters in indoor diffuse and specular environments.

    Science.gov (United States)

    Aminzadeh, Reza; Thielens, Arno; Bamba, Aliou; Kone, Lamine; Gaillot, Davy Paul; Lienard, Martine; Martens, Luc; Joseph, Wout

    2016-07-01

    For the first time, response of personal exposimeters (PEMs) is studied under diffuse field exposure in indoor environments. To this aim, both numerical simulations, using finite-difference time-domain method, and calibration measurements were performed in the range of 880-5875 MHz covering 10 frequency bands in Belgium. Two PEMs were mounted on the body of a human male subject and calibrated on-body in an anechoic chamber (non-diffuse) and a reverberation chamber (RC) (diffuse fields). This was motivated by the fact that electromagnetic waves in indoor environments have both specular and diffuse components. Both calibrations show that PEMs underestimate actual incident electromagnetic fields. This can be compensated by using an on-body response. Moreover, it is shown that these responses are different in anechoic chamber and RC. Therefore, it is advised to use an on-body calibration in an RC in future indoor PEM measurements where diffuse fields are present. Using the response averaged over two PEMs reduced measurement uncertainty compared to single PEMs. Following the calibration, measurements in a realistic indoor environment were done for wireless fidelity (WiFi-5G) band. Measured power density values are maximally 8.9 mW/m(2) and 165.8 μW/m(2) on average. These satisfy reference levels issued by the International Commission on Non-Ionizing Radiation Protection in 1998. Power density values obtained by applying on-body calibration in RC are higher than values obtained from no body calibration (only PEMs) and on-body calibration in anechoic room, by factors of 7.55 and 2.21, respectively. Bioelectromagnetics. 37:298-309, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  17. Turbulent diffusivity in the free atmosphere inferred from MST radar measurements: a review

    Directory of Open Access Journals (Sweden)

    R. Wilson

    2004-11-01

    Full Text Available The actual impact on vertical transport of small-scale turbulence in the free atmosphere is still a debated issue. Numerous estimates of an eddy diffusivity exist, clearly showing a lack of consensus. MST radars were, and continue to be, very useful for studying atmospheric turbulence, as radar measurements allow one to estimate the dissipation rates of energy (kinetic and potential associated with turbulent events. The two commonly used methods for estimating the dissipation rates, from the backscattered power and from the Doppler width, are discussed. The inference methods of a local diffusivity (local meaning here "within" the turbulent patch by using the dissipation rates are reviewed, with some of the uncertainty causes being stressed. Climatological results of turbulence diffusivity inferred from radar measurements are reviewed and compared.

    As revealed by high resolution MST radar measurements, atmospheric turbulence is intermittent in space and time. Recent theoretical works suggest that the effective diffusivity of such a patchy turbulence is related to statistical parameters describing the morphology of turbulent events: filling factor, lifetime and height of the patches. It thus appears that a statistical description of the turbulent patches' characteristics is required in order to evaluate and parameterize the actual impact of small-scale turbulence on transport of energy and materials. Clearly, MST radars could be an essential tool in that matter.

  18. Turbulent diffusivity in the free atmosphere inferred from MST radar measurements: a review

    Directory of Open Access Journals (Sweden)

    R. Wilson

    2004-11-01

    Full Text Available The actual impact on vertical transport of small-scale turbulence in the free atmosphere is still a debated issue. Numerous estimates of an eddy diffusivity exist, clearly showing a lack of consensus. MST radars were, and continue to be, very useful for studying atmospheric turbulence, as radar measurements allow one to estimate the dissipation rates of energy (kinetic and potential associated with turbulent events. The two commonly used methods for estimating the dissipation rates, from the backscattered power and from the Doppler width, are discussed. The inference methods of a local diffusivity (local meaning here "within" the turbulent patch by using the dissipation rates are reviewed, with some of the uncertainty causes being stressed. Climatological results of turbulence diffusivity inferred from radar measurements are reviewed and compared. As revealed by high resolution MST radar measurements, atmospheric turbulence is intermittent in space and time. Recent theoretical works suggest that the effective diffusivity of such a patchy turbulence is related to statistical parameters describing the morphology of turbulent events: filling factor, lifetime and height of the patches. It thus appears that a statistical description of the turbulent patches' characteristics is required in order to evaluate and parameterize the actual impact of small-scale turbulence on transport of energy and materials. Clearly, MST radars could be an essential tool in that matter.

  19. Analysis of Pumped Storage Plants (PSP) viability associated with other types of intermittent renewable energy

    Science.gov (United States)

    Andrade, J. G. P.; Barbosa, P. S. F.; Luvizotto, E., Jr.; Zuculin, S.; Pinto, Marrc; Tiago Filho, G. L.

    2014-03-01

    The energy generated by wind or solar photovoltaic (PV system) can be used by PSP to accumulate water in the upper reservoir, in the form of potential energy to be used later, during periods of high energy demand. This procedure offers the advantage of enabling the use of intermittent renewable energy source in times of growing needs of the electric power supply. The location of the PSP, the environmental aspects involved, their possible use for various purposes (stability of the power system at peak times, associate the turbine water for public supply purposes, among others) and the discussion of regulatory issues needs to be debated in the current context, where environmental issues require reliable sources of power generation and demand shows strong growth rates. A dynamic model is used to analyze the behavior of a PSP proposal for a site in Brazil, analyzing a complete cycle of its operation as a pump or turbine. The existing difficulties to use this proposal based on existing regulatory policies are also discussed, and a list of recommended adjustments is provided to allow the penetrations of PSP projects in the Brazilian institutional framework, coupled with other intermittent energy sources.

  20. Measurements of thermal diffusivity, specific heat capacity and thermal conductivity with LFA 447 apparatus

    DEFF Research Database (Denmark)

    Zajas, Jan Jakub; Heiselberg, Per

    The LFA 447 can be successfully used for measurements of thermal diffusivity, specific heat and thermal conductivity of various samples. It is especially useful when determining the properties of materials on a very small scale. The matrix measurement mode allows for determining the local...... properties with a fine resolution, down to 1 millimeter. Special attention needs to be taken when determining the specific heat capacity in the comparative method. First of all, the test and reference sample should be of nearly identical thickness. Secondly, their heat diffusion time should be comparable, so...... that the heat losses from both samples during the measurement are similar. Finally, the leveling of the samples is very important. Very small discrepancies can cause a massive error in the derivation of specific heat capacity and, as a result, thermal conductivity....

  1. Benefits of the Mycorrhizal Fungi in Tomato Leaves Measured by Open Photoacoustic Cell Technique: Interpretation of the Diffusion Parameters

    Science.gov (United States)

    Sánchez-Rocha, S.; Vargas-Luna, M.; Gutiérrez-Juárez, G.; Huerta-Franco, R.; Olalde-Portugal, V.

    2008-12-01

    The open photoacoustic cell technique was used to measure tomato leaves from plants with and without mycorrhizal fungi ( Glomus fasciculatum). Based on measurement of the photobaric contribution of the photoacoustic signal, the exponential parameter of the diffusion behavior for this contribution was calculated. From this value, the oxygen diffusion coefficient was derived. The changes in the oxygen- diffusion-coefficient-dependent exponential parameter are statistically significant ( p mycorrhizal symbiosis. Potentially similar results obtained from the photothermal contribution are discussed.

  2. Microscale Diffusion Measurements and Simulation of a Scaffold with a Permeable Strut

    Directory of Open Access Journals (Sweden)

    Songwan Jin

    2013-10-01

    Full Text Available Electrospun nanofibrous structures provide good performance to scaffolds in tissue engineering. We measured the local diffusion coefficients of 3-kDa FITC-dextran in line patterns of electrospun nanofibrous structures fabricated by the direct-write electrospinning (DWES technique using the fluorescence recovery after photobleaching (FRAP method. No significant differences were detected between DWES line patterns fabricated with polymer supplied at flow rates of 0.1 and 0.5 mL/h. The oxygen diffusion coefficients of samples were estimated to be ~92%–94% of the oxygen diffusion coefficient in water based on the measured diffusion coefficient of 3-kDa FITC-dextran. We also simulated cell growth and distribution within spatially patterned scaffolds with struts consisting of either oxygen-permeable or non-permeable material. The permeable strut scaffolds exhibited enhanced cell growth. Saturated depths at which cells could grow to confluence were 15% deeper for the permeable strut scaffolds than for the non-permeable strut scaffold.

  3. Interferometric measurement of a diffusion coefficient: comparison of two methods and uncertainty analysis

    Energy Technology Data Exchange (ETDEWEB)

    Riquelme, Rodrigo [Department of Mechanical and Metallurgical Engineering, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, Santiago (Chile); Lira, Ignacio [Department of Mechanical and Metallurgical Engineering, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, Santiago (Chile); Perez-Lopez, Carlos [Centro de Investigaciones en Optica (CIO), Leon, Gto 37150 (Mexico); Rayas, Juan A [Centro de Investigaciones en Optica (CIO), Leon, Gto 37150 (Mexico); RodrIguez-Vera, Ramon [Centro de Investigaciones en Optica (CIO), Leon, Gto 37150 (Mexico)

    2007-05-07

    Two methods to measure the diffusion coefficient of a species in a liquid by optical interferometry were compared. The methods were tested on a 1.75 M NaCl aqueous solution diffusing into water at 26 deg. C. Results were D = 1.587 x 10{sup -9} m{sup 2} s{sup -1} with the first method and D = 1.602 x 10{sup -9} m{sup 2} s{sup -1} with the second method. Monte Carlo simulation was used to assess the possible dispersion of these results. The standard uncertainties were found to be of the order of 0.05 x 10{sup -9} m{sup 2} s{sup -1} with both methods. We found that the value of the diffusion coefficient obtained by either method is very sensitive to the magnification of the optical system, and that if diffusion is slow the measurement of time does not need to be very accurate.

  4. Probe pressure effects on human skin diffuse reflectance and fluorescence spectroscopy measurements

    Science.gov (United States)

    Lim, Liang; Nichols, Brandon; Rajaram, Narasimhan; Tunnell, James W.

    2011-01-01

    Diffuse reflectance and fluorescence spectroscopy are popular research techniques for noninvasive disease diagnostics. Most systems include an optical fiber probe that transmits and collects optical spectra in contact with the suspected lesion. The purpose of this study is to investigate probe pressure effects on human skin spectroscopic measurements. We conduct an in-vivo experiment on human skin tissue to study the short-term (30 s) effects of probe pressure on diffuse reflectance and fluorescence measurements. Short-term light probe pressure (P0 physiological properties extracted from diffuse reflectance and fluorescence measurements, and less than 0 +/- 5% for diagnostically significant physiological properties. Absorption decreases with site-specific variations due to blood being compressed out of the sampled volume. Reduced scattering coefficient variation is site specific. Intrinsic fluorescence shows a large standard error, although no specific pressure-related trend is observed. Differences in tissue structure and morphology contribute to site-specific probe pressure effects. Therefore, the effects of pressure can be minimized when the pressure is small and applied for a short amount of time; however, long-term and large pressures induce significant distortions in measured spectra.

  5. New insights for accurate chemically specific measurements of slow diffusing molecules

    Science.gov (United States)

    Hou, Jianbo; Madsen, Louis A.

    2013-02-01

    Investigating the myriad features of molecular transport in materials yields fundamental information for understanding processes such as ion conduction, chemical reactions, and phase transitions. Molecular transport especially impacts the performance of ion-containing liquids and polymeric materials when used as electrolytes and separation media, with applications encompassing battery electrolytes, reverse-osmosis membranes, mechanical transducers, and fuel cells. Nuclear magnetic resonance (NMR) provides a unique probe of molecular translations by allowing measurement of all mobile species via spectral selectivity, access to a broad range of transport coefficients, probing of any material direction, and investigation of variable lengthscales in a material, thus, tying morphology to transport. Here, we present new concepts to test for and guarantee robust diffusion measurements. We first employ a standard pulsed-field-gradient (PFG) calibration protocol using 2H2O and obtain expected results, but we observe crippling artifacts when measuring 1H-glycerol diffusion with the same experimental parameters. A mathematical analysis of 2H2O and glycerol signals in the presence of PFG transients show tight agreement with experimental observations. These analyses lead to our principal findings that (1) negligible artifacts observed with low gyromagnetic ratio (γ) nuclei may become dominant when observing high γ nuclei, and (2) reducing the sample dimension along the gradient direction predictably reduces non-ideal behaviors of NMR signals. We further provide a useful quantitative strategy for error minimization when measuring diffusing species slower than the one used for gradient calibration.

  6. Semi-empirical approach for calibration of CR-39 detectors in diffusion chambers for radon measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pereyra A, P.; Lopez H, M. E. [Pontificia Universidad Catolica del Peru, Av. Universitaria 1801, San Miguel Lima 32 (Peru); Palacios F, D.; Sajo B, L. [Universidad Simon Bolivar, Laboratorio de Fisica Nuclear, Apartado 89000 Caracas (Venezuela, Bolivarian Republic of); Valdivia, P., E-mail: ppereyr@pucp.edu.pe [Universidad Nacional de Ingenieria, Av. Tupac Amaru s/n, Rimac, Lima 25 (Peru)

    2016-10-15

    Simulated and measured calibration of PADC detectors is given for cylindrical diffusion chambers employed in environmental radon measurements. The method is based on determining the minimum alpha energy (E{sub min}), average critical angle (<Θ{sub c}>), and fraction of {sup 218}Po atoms; the volume of the chamber (f{sub 1}), are compared to commercially available devices. Radon concentration for exposed detectors is obtained from induced track densities and the well-established calibration coefficient for NRPB monitor. Calibration coefficient of a PADC detector in a cylindrical diffusion chamber of any size is determined under the same chemical etching conditions and track analysis methodology. In this study the results of numerical examples and comparison between experimental calibration coefficients and simulation purpose made code. Results show that the developed method is applicable when uncertainties of 10% are acceptable. (Author)

  7. /sup 15/N/sub 2/ diffusion in soil during biological dinitrogen fixation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, M.P. (Lyon-1 Univ., 69 - Villeurbanne (France). Dept. de Biologie Vegetale); Warembourg, F.R. (Centre National de la Recherche Scientifique, 34 - Montpellier (France). Centre d' Etudes Phytosociologiques et Ecologiques Louis-Emberger)

    1983-01-01

    The kinetic of /sup 15/N/sub 2/ diffusion has been measured in a system similar to that for the estimation of N/sub 2/ fixation in plant microorganism associations cultivated in soil. The /sup 15/N/sub 2/ enrichment of the soil atmosphere reached an homogenous value one hour after injection of /sup 15/N/sub 2/ and is identical to that obtained by calculation, indicating that no adsorption occurs in the soil particles.

  8. Temperature Measurements in an Ethylene-Air-Opposed Flow Diffusion Flame

    Science.gov (United States)

    2012-01-01

    camera optical pyrometer to thermocouple measurements and Cantera simulations for opposed flow diffusion flames. Unlike thermocouples, optical...above the fuel duct was acquired from the optical pyrometer . A maximum centerline flame temperature of 1898 K at 3.70 mm above the fuel duct was...Nikkor 24-85 mm f/2.8-4D IF lens, which has a macro mode feature. To ensure near-infrared (IR) radiation was blocked from reaching the CMOS image

  9. Measurements of molecule diffusion on surfaces using neutron and helium spin echo

    Energy Technology Data Exchange (ETDEWEB)

    Fouquet, Peter [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)]. E-mail: fouquet@ill.fr; Hedgeland, Holly [Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Jardine, Andrew [Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Alexandrowicz, Gil [Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Allison, William [Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Ellis, John [Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2006-11-15

    We present a new approach to gain detailed surface-molecule potential information by combining neutron and helium atom scattering. First results are presented for a prototype study of benzene molecule diffusion on graphite surfaces. The measurements show good agreement and confirm the transferability of the results between the two methods. Future instrumental improvements are described that will improve the sensitivity of NSE by a factor of 50 for studies of molecules adsorbed on surfaces and mesoporous substrates.

  10. Wide-aperture laser beam measurement using transmission diffuser: errors modeling

    Science.gov (United States)

    Matsak, Ivan S.

    2015-06-01

    Instrumental errors of measurement wide-aperture laser beam diameter were modeled to build measurement setup and justify its metrological characteristics. Modeled setup is based on CCD camera and transmission diffuser. This method is appropriate for precision measurement of large laser beam width from 10 mm up to 1000 mm. It is impossible to measure such beams with other methods based on slit, pinhole, knife edge or direct CCD camera measurement. The method is suitable for continuous and pulsed laser irradiation. However, transmission diffuser method has poor metrological justification required in field of wide aperture beam forming system verification. Considering the fact of non-availability of a standard of wide-aperture flat top beam modelling is preferred way to provide basic reference points for development measurement system. Modelling was conducted in MathCAD. Super-Lorentz distribution with shape parameter 6-12 was used as a model of the beam. Using theoretical evaluations there was found that the key parameters influencing on error are: relative beam size, spatial non-uniformity of the diffuser, lens distortion, physical vignetting, CCD spatial resolution and, effective camera ADC resolution. Errors were modeled for 90% of power beam diameter criteria. 12-order Super-Lorentz distribution was primary model, because it precisely meets experimental distribution at the output of test beam forming system, although other orders were also used. The analytic expressions were obtained analyzing the modelling results for each influencing data. Attainability of <1% error based on choice of parameters of expression was shown. The choice was based on parameters of commercially available components of the setup. The method can provide up to 0.1% error in case of using calibration procedures and multiple measurements.

  11. Mapping of the binding sites involved in PSP94-CRISP-3 interaction by molecular dissection of the complex.

    Science.gov (United States)

    Breed, Ananya A; Gomes, Amanda; Roy, Binita Sur; Mahale, Smita D; Pathak, Bhakti R

    2013-04-01

    Human Prostate Secretory Protein of 94 amino acids (PSP94) has been shown to bind human CRISP-3 (cysteine-rich secretory protein 3) with very high affinity. CRISP-3 belongs to the CRISP family of proteins having a PR-1 (pathogenesis related protein 1) domain at its N-terminal and ion channel regulatory (ICR) domain at its C-terminal connected by a hinge region. Functional significance of this complex is not yet known. In order to identify the residues and/or regions involved in PSP94-CRISP-3 interaction, site-directed mutagenesis was employed. Effect of the mutations on the interaction was studied by co-immunoprecipitation (Co-IP). For PSP94, amino acids Y(3), F(4), P(56) and the C-terminal β-strand were found to be crucial for interacting with CRISP-3. A disulfide bond between the two domains of PSP94 (C(37)A-C(73)A) was also important for this interaction. In case of CRISP-3, the N-terminal domain alone could not maintain a strong interaction with PSP94 but it required presence of the hinge region and not the C-terminal domain. Apart from CRISP-3, CRISP-2 was also found to interact with human PSP94. Based on our findings the most likely model of PSP94-CRISP-3 complex has been proposed. The terminal β-strands of PSP94 contact the first α-helix and the hinge region of CRISP-3. Involvement of the hinge region of CRISPs in interaction with PSP94 may affect the domain movement of CRISPs essential for the ion-channel regulatory activity resulting in inhibition of this activity. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Check-All-That-Apply (CATA), Sorting, and Polarized Sensory Positioning (PSP) with Astringent Stimuli.

    Science.gov (United States)

    Fleming, Erin E; Ziegler, Gregory R; Hayes, John E

    2015-10-01

    Multiple rapid sensory profiling techniques have been developed as more efficient alternatives to traditional sensory descriptive analysis. Here, we compare the results of three rapid sensory profiling techniques - check-all-that-apply (CATA), sorting, and polarized sensory positioning (PSP) - using a diverse range of astringent stimuli. These rapid methods differ in their theoretical basis, implementation, and data analyses, and the relative advantages and limitations are largely unexplored. Additionally, we were interested in using these methods to compare varied astringent stimuli, as these compounds are difficult to characterize using traditional descriptive analysis due to high fatigue and potential carry-over. In the CATA experiment, subjects (n=41) were asked to rate the overall intensity of each stimulus as well as to endorse any relevant terms (from a list of 13) which characterized the sample. In the sorting experiment, subjects (n=30) assigned intensity-matched stimuli into groups 1-on-1 with the experimenter. In the PSP experiment, (n=41) subjects first sampled and took notes on three blind references ('poles') before rating each stimulus for its similarity to each of the 3 poles. Two-dimensional perceptual maps from correspondence analysis (CATA), multidimensional scaling (sorting), and multiple factor analysis (PSP) were remarkably similar, with normalized RV coefficients indicating significantly similar plots, regardless of method. Agglomerative hierarchical clustering of all data sets using Ward's minimum variance as the linkage criteria showed the clusters of astringent stimuli were approximately based on the respective class of astringent agent. Based on the descriptive CATA data, it appears these differences may be due to the presence of side tastes such as bitterness and sourness, rather than astringent sub-qualities per se. Although all three methods are considered 'rapid,' our prior experience with sorting suggests it is best performed 1

  13. Using Noise and Fluctuations for In Situ Measurements of Nitrogen Diffusion Depth

    Science.gov (United States)

    Samoila, Cornel; Ursutiu, Doru; Schleer, Walter-Harald; Jinga, Vlad; Nascov, Victor

    2016-01-01

    In manufacturing processes involving diffusion (of C, N, S, etc.), the evolution of the layer depth is of the utmost importance: the success of the entire process depends on this parameter. Currently, nitriding is typically either calibrated using a “post process” method or controlled via indirect measurements (H2, O2, H2O + CO2). In the absence of “in situ” monitoring, any variation in the process parameters (gas concentration, temperature, steel composition, distance between sensors and furnace chamber) can cause expensive process inefficiency or failure. Indirect measurements can prevent process failure, but uncertainties and complications may arise in the relationship between the measured parameters and the actual diffusion process. In this paper, a method based on noise and fluctuation measurements is proposed that offers direct control of the layer depth evolution because the parameters of interest are measured in direct contact with the nitrided steel (represented by the active electrode). The paper addresses two related sets of experiments. The first set of experiments consisted of laboratory tests on nitrided samples using Barkhausen noise and yielded a linear relationship between the frequency exponent in the Hooge equation and the nitriding time. For the second set, a specific sensor based on conductivity noise (at the nitriding temperature) was built for shop-floor experiments. Although two different types of noise were measured in these two sets of experiments, the use of the frequency exponent to monitor the process evolution remained valid. PMID:28773941

  14. Using Noise and Fluctuations for In Situ Measurements of Nitrogen Diffusion Depth.

    Science.gov (United States)

    Samoila, Cornel; Ursutiu, Doru; Schleer, Walter-Harald; Jinga, Vlad; Nascov, Victor

    2016-10-05

    In manufacturing processes involving diffusion (of C, N, S, etc.), the evolution of the layer depth is of the utmost importance: the success of the entire process depends on this parameter. Currently, nitriding is typically either calibrated using a "post process" method or controlled via indirect measurements (H2, O2, H2O + CO2). In the absence of "in situ" monitoring, any variation in the process parameters (gas concentration, temperature, steel composition, distance between sensors and furnace chamber) can cause expensive process inefficiency or failure. Indirect measurements can prevent process failure, but uncertainties and complications may arise in the relationship between the measured parameters and the actual diffusion process. In this paper, a method based on noise and fluctuation measurements is proposed that offers direct control of the layer depth evolution because the parameters of interest are measured in direct contact with the nitrided steel (represented by the active electrode). The paper addresses two related sets of experiments. The first set of experiments consisted of laboratory tests on nitrided samples using Barkhausen noise and yieded a linear relationship between the frequency exponent in the Hooge equation and the nitriding time. For the second set, a specific sensor based on conductivity noise (at the nitriding temperature) was built for shop-floor experiments. Although two different types of noise were measured in these two sets of experiments, the use of the frequency exponent to monitor the process evolution remained valid.

  15. Histogram analysis of diffusion measures in clinically isolated syndromes and relapsing-remitting multiple sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Yu Chunshui [Department of Radiology, Xuanwu Hospital of Capital Medical University, Beijing (China); Education Ministry Key Laboratory for Neurodegenerative Disease, Beijing (China); Lin Fuchun [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China); Liu Yaou; Duan Yunyun [Department of Radiology, Xuanwu Hospital of Capital Medical University, Beijing (China); Lei Hao [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China); Li Kuncheng [Department of Radiology, Xuanwu Hospital of Capital Medical University, Beijing (China); Education Ministry Key Laboratory for Neurodegenerative Disease, Beijing (China)], E-mail: kunchengli1955@yahoo.com.cn

    2008-11-15

    Objective: The purposes of our study were to employ diffusion tensor imaging (DTI)-based histogram analysis to determine the presence of occult damage in clinically isolated syndrome (CIS), to compare its severity with relapsing-remitting multiple sclerosis (RRMS), and to determine correlations between DTI histogram measures and clinical and MRI indices in these two diseases. Materials and methods: DTI scans were performed in 19 CIS and 19 RRMS patients and 19 matched healthy volunteers. Histogram analyses of mean diffusivity and fractional anisotropy were performed in normal-appearing brain tissue (NABT), normal-appearing white matter (NAWM) and gray matter (NAGM). Correlations were analyzed between these measures and expanded disability status scale (EDSS) scores, T{sub 2}WI lesion volumes (LV) and normalized brain tissue volumes (NBTV) in CIS and RRMS patients. Results: Significant differences were found among CIS, RRMS and control groups in the NBTV and most of the DTI histogram measures of the NABT, NAWM and NAGM. In CIS patients, some DTI histogram measures showed significant correlations with LV and NBTV, but none of them with EDSS. In RRMS patients, however, some DTI histogram measures were significantly correlated with LV, NBTV and EDSS. Conclusion: Occult damage occurs in both NAGM and NAWM in CIS, but the severity is milder than that in RRMS. In CIS and RRMS, the occult damage might be related to both T2 lesion load and brain tissue atrophy. Some DTI histogram measures might be useful for assessing the disease progression in RRMS patients.

  16. Quantitative tract-specific measures of uncinate and cingulum in major depression using diffusion tensor imaging.

    Science.gov (United States)

    Zhang, Aifeng; Leow, Alex; Ajilore, Olusola; Lamar, Melissa; Yang, Shaolin; Joseph, Josh; Medina, Jennifer; Zhan, Liang; Kumar, Anand

    2012-03-01

    Previous findings suggested the role of the prefrontal cortex, hippocampus, and cingulate gyrus in major depressive disorders (MDD), but the white matter microstructural abnormalities of the fibers connecting these brain structures are not known. The purpose of this study was to test the hypothesis that white matter abnormalities are present in association fibers of the uncinate fasciculus (UF) and cingulum bundle (CB) among MDD subjects. A total of 21 MDD subjects aged between 30 and 65 years and 21 age-matched healthy controls (HC) were recruited. All subjects were right-handed and without history of diabetes or other cardiac diseases. We extracted quantitative tract-specific measures based on diffusion tensor imaging tractography to examine both diffusivity and geometric properties of the UF and CB. Significantly decreased fractional anisotropy (FA) and increased radial diffusivity of the right UF were observed in MDD patients compared with HC (pR) in both groups in the FA measure of the CB. Our study demonstrates novel findings of white matter microstructural abnormalities of the right UF in MDD. In the MDD group, the severity of depression is associated with reduced NNF in the right UF. These findings have implications for both clinical manifestations of depression as well as its pathophysiology.

  17. Measurement of gas-switching related diffusion phenomena in horizontal MOCVD reactors using biacetyl luminescence

    Science.gov (United States)

    Visser, E. P.; Govers, C. A. M.; Giling, L. J.

    1990-05-01

    The fading of concentration profiles due to diffusion, occuring after gas source switching in MOCVD growth, was simulated by biacetyl luminescence experiments. In particular the influence of thermally induced memory cells on the concentration transients was investigated. Biacetyl molecules were used instead of macroscopic particles (for instance TiO 2) because not only can the flow patterns thus be visualized, but also a more realistic simulation of diffusion phenomena is obtained. It is shown that memory cells give rise to an increase of the residence times of gases inside the reactor. For typical MOCVD conditions, increases of several seconds were measured. The influence on interface sharpness of a GaAs/AlGaAs heterojunction is discussed. Residence times were recorded as a function of the most important hydrodynamic parameters in the MOCVD process, both at atmospheric pressure and at low pressure.

  18. Fast Responding PSP for Rotorcraft Aerodynamic Investigations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed work focuses on implementing fast-response pressure-sensitive paint and Surface Stress Sensitive Films for measurements of unsteady pressure and skin...

  19. Fast Responding PSP for Rotorcraft Aerodynamic Investigations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall objective of the Phase I program was to demonstrate a system for simultaneous measurements of unsteady pressure and model geometry. During the Phase I...

  20. The epidermal resistance to diffusion of water vapour : an improved measuring method and field results in Indian corn (Zea mays)

    NARCIS (Netherlands)

    Stigter, C.J.

    1974-01-01

    The resistance of the epidermis of the leaf to diffusion of water vapour can be measured most accurately in the field by closed diffusion porometers. It was possible to overcome the problems related to calibration and to dynamical use of a LiCl humidity sensor in the porometer. The dynamic behaviour

  1. Diffuse reflectance spectra measured in vivo in human tissues during Photofrin-mediated pleural photodynamic therapy

    Science.gov (United States)

    Finlay, Jarod C.; Zhu, Timothy C.; Dimofte, Andreea; Friedberg, Joseph S.; Hahn, Stephen M.

    2006-02-01

    Optimal delivery of light in photodynamic therapy (PDT) requires not only optimal placement and power of light sources, but knowledge of the dynamics of light propagation in the tissue being treated and in the surrounding normal tissue, and of their respective accumulations of sensitizer. In an effort to quantify both tissue optical properties and sensitizer distribution, we have measured fluorescence emission and diffuse reflectance spectra at the surface of a variety of tissue types in the thoracic cavities of human patients. The patients studied here were enrolled in Phase II clinical trials of Photofrin-mediated PDT for the treatment of non-small cell lung cancer and cancers with pleural effusion. Patients were given Photofrin at dose of 2 mg per kg body weight 24 hours prior to treatment. Each patient received surgical resection of the affected lung and pleura. Patients received intracavity PDT at 630nm to a dose of 30 J/cm2, as determined by isotropic detectors sutured to the cavity walls. We measured the diffuse reflectance spectra before and after PDT in various positions within the cavity, including tumor, diaphragm, pericardium, skin, and chest wall muscle in 5 patients. The measurements we acquired using a specially designed fiber optic-based probe consisting of one fluorescence excitation fiber, one white light delivery fiber, and 9 detection fibers spaced at distances from 0.36 to 7.8 mm from the source, all of which are imaged via a spectrograph onto a CCD, allowing measurement of radially-resolved diffuse reflectance and fluorescence spectra. The light sources for these two measurements (a 403-nm diode laser and a halogen lamp, respectively) were blocked by computer-controlled shutters, allowing sequential fluorescence, reflectance, and background acquisition. The diffuse reflectance was analyzed to determine the absorption and scattering spectra of the tissue and from these, the concentration and oxygenation of hemoglobin and the local drug uptake

  2. Direct measurement of sequence-dependent transition path times and conformational diffusion in DNA duplex formation.

    Science.gov (United States)

    Neupane, Krishna; Wang, Feng; Woodside, Michael T

    2017-02-07

    The conformational diffusion coefficient, D, sets the timescale for microscopic structural changes during folding transitions in biomolecules like nucleic acids and proteins. D encodes significant information about the folding dynamics such as the roughness of the energy landscape governing the folding and the level of internal friction in the molecule, but it is challenging to measure. The most sensitive measure of D is the time required to cross the energy barrier that dominates folding kinetics, known as the transition path time. To investigate the sequence dependence of D in DNA duplex formation, we measured individual transition paths from equilibrium folding trajectories of single DNA hairpins held under tension in high-resolution optical tweezers. Studying hairpins with the same helix length but with G:C base-pair content varying from 0 to 100%, we determined both the average time to cross the transition paths, τtp, and the distribution of individual transit times, PTP(t). We then estimated D from both τtp and PTP(t) from theories assuming one-dimensional diffusive motion over a harmonic barrier. τtp decreased roughly linearly with the G:C content of the hairpin helix, being 50% longer for hairpins with only A:T base pairs than for those with only G:C base pairs. Conversely, D increased linearly with helix G:C content, roughly doubling as the G:C content increased from 0 to 100%. These results reveal that G:C base pairs form faster than A:T base pairs because of faster conformational diffusion, possibly reflecting lower torsional barriers, and demonstrate the power of transition path measurements for elucidating the microscopic determinants of folding.

  3. Estudio del Proceso Software Personal (PSP en un entorno académico

    Directory of Open Access Journals (Sweden)

    Omar S. Gómez

    2014-05-01

    Full Text Available El Proceso Software Personal (En Inglés, Personal Software Process o PSP es un proceso individual cuyo objetivo es ayudar a los ingenieros en software a medir y mejorar su productividad personal. El PSP suele enseñarse exclusivamente a profesionales, no obstante éste ha comenzado a incluirse como parte de cursos universitarios. En este trabajo se presenta un estudio sobre PSP efectuado en un entorno académico donde se analizan los siguientes indicadores: precisión en las estimaciones de tamaño y esfuerzo, calidad del producto así como productividad. Los resultados aquí reportados sugieren una mejoría parcial con respecto a la precisión de las estimaciones, una reducción sustantiva en la densidad de defectos de acuerdo a un factor de 6.6 y una productividad media de 53 líneas de código fuente por hora.

  4. dbPSP: a curated database for protein phosphorylation sites in prokaryotes.

    Science.gov (United States)

    Pan, Zhicheng; Wang, Bangshan; Zhang, Ying; Wang, Yongbo; Ullah, Shahid; Jian, Ren; Liu, Zexian; Xue, Yu

    2015-01-01

    As one of the most important post-translational modifications, phosphorylation is highly involved in almost all of biological processes through temporally and spatially modifying substrate proteins. Recently, phosphorylation in prokaryotes attracted much attention for its critical roles in various cellular processes such as signal transduction. Thus, an integrative data resource of the prokaryotic phosphorylation will be useful for further analysis. In this study, we presented a curated database of phosphorylation sites in prokaryotes (dbPSP, Database URL: http://dbpsp.biocuckoo.org) for 96 prokaryotic organisms, which belong to 11 phyla in two domains including bacteria and archaea. From the scientific literature, we manually collected experimentally identified phosphorylation sites on seven types of residues, including serine, threonine, tyrosine, aspartic acid, histidine, cysteine and arginine. In total, the dbPSP database contains 7391 phosphorylation sites in 3750 prokaryotic proteins. With the dataset, the sequence preferences of the phosphorylation sites and functional annotations of the phosphoproteins were analyzed, while the results shows that there were obvious differences among the phosphorylation in bacteria, archaea and eukaryotes. All the phosphorylation sites were annotated with original references and other descriptions in the database, which could be easily accessed through user-friendly website interface including various search and browse options. Taken together, the dbPSP database provides a comprehensive data resource for further studies of protein phosphorylation in prokaryotes. Database URL: http://dbpsp.biocuckoo.org © The Author(s) 2015. Published by Oxford University Press.

  5. Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films.

    Science.gov (United States)

    Cusnir, Ruslan; Steinmann, Philipp; Christl, Marcus; Bochud, François; Froidevaux, Pascal

    2015-11-09

    The biological uptake of plutonium (Pu) in aquatic ecosystems is of particular concern since it is an alpha-particle emitter with long half-life which can potentially contribute to the exposure of biota and humans. The diffusive gradients in thin films technique is introduced here for in-situ measurements of Pu bioavailability and speciation. A diffusion cell constructed for laboratory experiments with Pu and the newly developed protocol make it possible to simulate the environmental behavior of Pu in model solutions of various chemical compositions. Adjustment of the oxidation states to Pu(IV) and Pu(V) described in this protocol is essential in order to investigate the complex redox chemistry of plutonium in the environment. The calibration of this technique and the results obtained in the laboratory experiments enable to develop a specific DGT device for in-situ Pu measurements in freshwaters. Accelerator-based mass-spectrometry measurements of Pu accumulated by DGTs in a karst spring allowed determining the bioavailability of Pu in a mineral freshwater environment. Application of this protocol for Pu measurements using DGT devices has a large potential to improve our understanding of the speciation and the biological transfer of Pu in aquatic ecosystems.

  6. Apparent Diffusion Coefficient Measurement in Mediastinal Lymphadenopathies: Differentiation between Benign and Malignant Lesions

    Directory of Open Access Journals (Sweden)

    Fethi Emre Ustabasioglu

    2017-01-01

    Full Text Available Objectives: We aimed to prospectively assess the diagnostic value of apparent diffusion coefficient (ADC measurement in the differentiation of benign and malignant mediastinal lymphadenopathies. Materials and Methods: The study included 63 consecutive patients (28 women, 35 men; mean age 59.3 years with 125 mediastinal lymphadenopathies. Echoplanar diffusion-weighted magnetic resonance imaging of the mediastinum was performed with b-factors of 0 and 600 mm2/s before mediastinoscopy and mediastinotomy, and ADC values were measured. The ADC values were compared with the histological results, and statistical analysis was done. P < 0.05 was considered statistically significant. Results: The mean ADC value of malignant mediastinal lymphadenopathy (1.030 ± 0.245 × 10−3 mm2/s was significantly lower (P < 0.05 when compared to benign lymphadenopathies (1.571 ± 0.559 × 10−3 mm2/s. For differentiating malignant from benign mediastinal lymphadenopathy, the best result was obtained when an ADC value of 1.334 × 10−3 mm2/s was used as a threshold value; area under the curve 0.848, accuracy 78.4%, sensitivity 66%, specificity of 86%, positive predictive value 76.7%, and negative predictive value of 79.2%. Interobserver agreement was excellent for ADC measurements. Conclusions: ADC measurements could be considered an important supportive method in differentiating benign from malignant mediastinal lymphadenopathies.

  7. Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise

    Science.gov (United States)

    Henry, Brad; Zhao, Mingjun; Shang, Yu; Uhl, Timothy; Thomas, D. Travis; Xenos, Eleftherios S.; Saha, Sibu P.; Yu, Guoqiang

    2015-12-01

    Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of forearm muscle hemodynamics during handgrip exercises. The translation of these techniques from the forearm to the lower limb is the goal of this study as various diseases preferentially affect muscles in the lower extremity. This study adapted a hybrid near-infrared spectroscopy and diffuse correlation spectroscopy system with a gating algorithm to continuously quantify hemodynamic responses of medial gastrocnemius during plantar flexion exercises in 10 healthy subjects. The outcomes from optical measurement include oxy-, deoxy-, and total hemoglobin concentrations, blood oxygen saturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV˙O2). We calibrated rBF and rV˙O2 profiles with absolute baseline values of BF and V˙O2 obtained by venous and arterial occlusions, respectively. Results from this investigation were comparable to values from similar studies. Additionally, significant correlation was observed between resting local muscle BF measured by the optical technique and whole limb BF measured concurrently by a strain gauge venous plethysmography. The extensive hemodynamic and metabolic profiles during exercise will allow for future comparison studies to investigate the diagnostic value of hybrid technologies in muscles affected by disease.

  8. The measurement of self-diffusion coefficients in liquid metals with quasielastic neutron scattering

    Directory of Open Access Journals (Sweden)

    Meyer Andreas

    2015-01-01

    Full Text Available Quasielastic incoherent neutron scattering (QENS has proven to be a versatile tool to study self diffusion of atoms in liquid metals. Here it is shown, that coherent contributions to the signal in the small q limit appear as a flat and energy independent constant to the QENS signal in single-component liquid metals even for systems with a small incoherent scattering cross section, like aluminum. Container-less processing via electromagnetic or electrostatic levitation devices, especially designed for QENS, enables the in-situ measurement on liquid metallic droplets of sizes between 5 mm to 10 mm in diameter. This gives access to the study of chemically reactive, refractory metallic melts and extends the accessible temperature range to undercoolings of several hundred Kelvin below the respective melting point. Compared to experiments using a thin-walled crucible giving hollow-cylindrical sample geometry it is shown that multiple scattering on levitated droplets is negligible for the analysis of the self-diffusion coefficient. QENS results of liquid germanium and 73germanium isotope mixtures, titanium, nickel, copper and aluminum are reviewed. The self-diffusion coefficients of these systems are best described by an Arrhenius-type temperature dependence around their respective melting points.

  9. DCCO and SCCO: measurements of diffusion coefficients and of thermodiffusion in microgravity; DCCO et SCCO: mesures de coefficients de diffusion et de thermodiffusion en microgravite

    Energy Technology Data Exchange (ETDEWEB)

    Legros, J.C.; Van Vaerenbergh, S.; Dubois, F.; Decroly, Y. [Universite Libre de Bruxelles (Belgium); Montel, F. [ELF-Aquitaine Production, 64 - Pau (France); Goodman, S. [C-CORE, New Foundland, (Canada); Bekaert, G. [SABCA, Bruxelles (Belgium); Van Ransbeek, E. [IASB-BIRA, Bruxelles (Belgium)

    1996-12-31

    Measurements of diffusion coefficients of ternary systems and of thermodiffusion coefficients of multicomponent systems, including crude oils, have been undertaken by MRC and Elf-Aquitaine. The experiments DCCO and SCCO (respectively Diffusion and Soret Coefficients of Crude Oils) will be performed in 1997 and 1998 in GAS containers on the Space Shuttle. The 9 systems of DCCO are analyzed by Mach-Zehnder bicolor interferometry. The samples of the 18 systems of SCCO, among which three at 300 bars and at a mean temperature of 60 deg. C, will be analyzed after recovery on ground by a chromatographic technique. Such measurements performed in microgravity, like the measurements of Soret coefficients of binary solutions performed in the microgravity SCM experiments, are necessary reference measurements. (authors) 12 refs.

  10. Diffusion tensor imaging of the kidney at 3 Tesla MRI: normative values and repeatability of measurements in healthy volunteers.

    Science.gov (United States)

    Gürses, Bengi; Kiliçkesmez, Ozgür; Taşdelen, Neslihan; Firat, Zeynep; Gürmen, Nevzat

    2011-12-01

    To evaluate the feasibility of renal diffusion tensor imaging and determine the normative fractional anisotropy and apparent diffusion coefficient values at 3 Tesla magnetic resonance imaging (MRI) using parallel imaging and free breathing technique. A total of 52 young healthy volunteers with no history of renal disease were included in the study. MRI examinations were performed with 3 Tesla MRI equipment, using six-channel phased array SENSE Torso coil. In all subjects, T2-weighted turbo spin echo and diffusion tensor imaging using single shot echo planar imaging sequences were obtained in the coronal plane with free breathing. Field of view, slice thickness, and slice gap values were identical for both sequences for anatomic correlation during analysis of diffusion tensor imaging data. Parallel imaging method was used with a SENSE factor of 2. Diffusion tensor parameters of the cortex and medulla were determined and the intra- and inter-observer measurement variances were calculated. The mean fractional anisotropy of the medulla was significantly higher than that of the cortex, whereas the mean apparent diffusion coefficient of the medulla was lower when compared with that of the cortex. According to the two-sided paired samples Student's t test, the intra- and inter-observer measurements correlated well. This study shows the feasibility of renal diffusion tensor imaging and repeatibility of diffusion tensor parameter measurements in 3 Tesla MRI.

  11. Ultra-low-field NMR relaxation and diffusion measurements using an optical magnetometer.

    Science.gov (United States)

    Ganssle, Paul J; Shin, Hyun D; Seltzer, Scott J; Bajaj, Vikram S; Ledbetter, Micah P; Budker, Dmitry; Knappe, Svenja; Kitching, John; Pines, Alexander

    2014-09-08

    Nuclear magnetic resonance (NMR) relaxometry and diffusometry are important tools for the characterization of heterogeneous materials and porous media, with applications including medical imaging, food characterization and oil-well logging. These methods can be extremely effective in applications where high-resolution NMR is either unnecessary, impractical, or both, as is the case in the emerging field of portable chemical characterization. Here, we present a proof-of-concept experiment demonstrating the use of high-sensitivity optical magnetometers as detectors for ultra-low-field NMR relaxation and diffusion measurements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Chamber and Diffusive Based Carbon Flux Measurements in an Alaskan Arctic Ecosystem

    Science.gov (United States)

    Wilkman, E.; Oechel, W. C.; Zona, D.

    2013-12-01

    Eric Wilkman, Walter Oechel, Donatella Zona Comprising an area of more than 7 x 106 km2 and containing over 11% of the world's organic matter pool, Arctic terrestrial ecosystems are vitally important components of the global carbon cycle, yet their structure and functioning are sensitive to subtle changes in climate and many of these functional changes can have large effects on the atmosphere and future climate regimes (Callaghan & Maxwell 1995, Chapin et al. 2002). Historically these northern ecosystems have acted as strong C sinks, sequestering large stores of atmospheric C due to photosynthetic dominance in the short summer season and low rates of decomposition throughout the rest of the year as a consequence of cold, nutrient poor, and generally water-logged conditions. Currently, much of this previously stored carbon is at risk of loss to the atmosphere due to accelerated soil organic matter decomposition in warmer future climates (Grogan & Chapin 2000). Although there have been numerous studies on Arctic carbon dynamics, much of the previous soil flux work has been done at limited time intervals, due to both the harshness of the environment and labor and time constraints. Therefore, in June of 2013 an Ultraportable Greenhouse Gas Analyzer (UGGA - Los Gatos Research Inc.) was deployed in concert with the LI-8100A Automated Soil Flux System (LI-COR Biosciences) in Barrow, AK to gather high temporal frequency soil CO2 and CH4 fluxes from a wet sedge tundra ecosystem. An additional UGGA in combination with diffusive probes, installed in the same location, provides year-round soil and snow CO2 and CH4 concentrations. When used in combination with the recently purchased AlphaGUARD portable radon monitor (Saphymo GmbH), continuous soil and snow diffusivities and fluxes of CO2 and CH4 can be calculated (Lehmann & Lehmann 2000). Of particular note, measuring soil gas concentration over a diffusive gradient in this way allows one to separate both net production and

  13. A comparison of film and 3 digital imaging systems for natural dental caries detection: CCD, CMOS, PSP and film

    Energy Technology Data Exchange (ETDEWEB)

    Han, Won Jeong [Dankook University College of Medicine, Seoul (Korea, Republic of)

    2004-03-15

    To evaluate the diagnostic accuracy of occlusal and proximal caries detection using CCD, CMOS, PSP and film system. 32 occlusal and 30 proximal tooth surfaces were radiographed under standardized conditions using 3 digital systems; CCD (CDX-2000HQ, Biomedysis Co., Seoul, Korea), CMOS (Schick, Schick Inc., Long Island, USA), PSP (Digora FMX, Orion Co./Soredex, Helsinki, Finland) and 1 film system (Kodak Insight, Eastman Kodak, Rochester, USA). 5 observers examined the radiographs for occlusal and proximal caries using a 5-point confidence scale. The presence of caries was validated histologically and radiographically. Diagnostic accuracy was evaluated using ROC curve areas (AZ). Analysis using ROC curves revealed the area under each curve which indicated a diagnostic accuracy. For occlusal caries, Kodak Insight film had an Az of 0.765, CCD one of 0.730, CMOS one of 0.742 and PSP one of 0.735. For proximal caries, Kodak Insight film had an Az of 0.833, CCD one of 0.832, CMOS one of 0.828 and PSP one of 0.868. No statistically significant difference was noted between any of the imaging modalities. CCD, CMOS, PSP and film performed equally well in the detection of occlusal and proximal dental caries. CCD, CMOS and PSP-based digital images provided a level of diagnostic performance comparable to Kodak Insight film.

  14. Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements

    Science.gov (United States)

    Wang, H.; Porter, W. D.; Dinwiddie, R. B.

    2017-07-01

    We report the laser-induced pressure-wave and the barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (<1 ms) and negative transients during laser flash measurements were captured using the infrared detector on thin, high thermal conductivity samples. The standard thermal diffusivity analysis only focuses on the longer time scale thermal transient measured from the back-surface due to heat conduction. Previously, these negative transients or spikes were filtered out and ignored as noise or anomaly from the instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (<100 μs) is also known as the thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about 1 ms. The pressure-wave induced thermal signal was systematically studied and analyzed. The underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.

  15. Measurement of thermal conductivity and thermal diffusivity using a thermoelectric module

    Science.gov (United States)

    Beltrán-Pitarch, Braulio; Márquez-García, Lourdes; Min, Gao; García-Cañadas, Jorge

    2017-04-01

    A proof of concept of using a thermoelectric module to measure both thermal conductivity and thermal diffusivity of bulk disc samples at room temperature is demonstrated. The method involves the calculation of the integral area from an impedance spectrum, which empirically correlates with the thermal properties of the sample through an exponential relationship. This relationship was obtained employing different reference materials. The impedance spectroscopy measurements are performed in a very simple setup, comprising a thermoelectric module, which is soldered at its bottom side to a Cu block (heat sink) and thermally connected with the sample at its top side employing thermal grease. Random and systematic errors of the method were calculated for the thermal conductivity (18.6% and 10.9%, respectively) and thermal diffusivity (14.2% and 14.7%, respectively) employing a BCR724 standard reference material. Although errors are somewhat high, the technique could be useful for screening purposes or high-throughput measurements at its current state. This new method establishes a new application for thermoelectric modules as thermal properties sensors. It involves the use of a very simple setup in conjunction with a frequency response analyzer, which provides a low cost alternative to most of currently available apparatus in the market. In addition, impedance analyzers are reliable and widely spread equipment, which facilities the sometimes difficult access to thermal conductivity facilities.

  16. Experimental measurement of time-dependent photon scatter for diffuse optical tomography.

    Science.gov (United States)

    Valim, Niksa; Brock, James; Niedre, Mark

    2010-01-01

    Time-resolved measurement of early arriving photons through diffusive media has been shown to effectively reduce the high degree of light scatter in biological tissue. However, the experimentally achievable reduction in photon scatter and the impact of time-gated detection on instrument noise performance is not well understood. We measure time-dependent photon density sensitivity functions (PDSFs) between a pulsed laser source and a photomultiplier tube operating in time-correlated single-photon-counting mode. Our data show that with our system, measurement of early arriving photons reduces the full width half maximum of PDSFs on average by about 40 to 60% versus quasicontinuous wave photons over a range of experimental conditions similar to those encountered in small animal tomography, corresponding to a 64 to 84% reduction in PDSF volume. Factoring in noise considerations, the optimal operating point of our instrument is determined to be about the 10% point on the rising edge of the transmitted intensity curve. Time-dependent Monte Carlo simulations and the time-resolved diffusion approximation are used to model photon propagation and are evaluated for agreement with experimental data.

  17. Noninvasive photoacoustic measurement of absorption coefficient using internal light irradiation of cylindrical diffusing fiber

    Science.gov (United States)

    Peng, Dong-qing; Zhu, Li-li; Li, Zhi-fang; Li, Hui

    2017-09-01

    Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber (CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy.

  18. Method of measuring blood oxygenation based on spectroscopy of diffusely scattered light

    Science.gov (United States)

    Kleshnin, M. S.; Orlova, A. G.; Kirillin, M. Yu.; Golubyatnikov, G. Yu.; Turchin, I. V.

    2017-05-01

    A new approach to the measurement of blood oxygenation is developed and implemented, based on an original two-step algorithm reconstructing the relative concentration of biological chromophores (haemoglobin, water, lipids) from the measured spectra of diffusely scattered light at different distances from the radiation source. The numerical experiments and approbation of the proposed approach using a biological phantom have shown the high accuracy of the reconstruction of optical properties of the object in question, as well as the possibility of correct calculation of the haemoglobin oxygenation in the presence of additive noises without calibration of the measuring device. The results of the experimental studies in animals agree with the previously published results obtained by other research groups and demonstrate the possibility of applying the developed method to the monitoring of blood oxygenation in tumour tissues.

  19. Investigation of ESEM/EDX to measure liquor penetration and diffusion in Eucalyptus grandis wood chips during kraft pulping

    CSIR Research Space (South Africa)

    Grzeskowiak, V

    2011-01-01

    Full Text Available Environmental scanning electron microscopy coupled with energy dispersive x-ray (ESEM/EDX) was optimised to measure the penetration and diffusion of cooking liquor into Eucalyptus grandis wood chips during kraft pulping. The moisture content...

  20. Diffusion tensor imaging of Parkinson's disease, multiple system atrophy and progressive supranuclear palsy: a tract-based spatial statistics study.

    Directory of Open Access Journals (Sweden)

    Amanda Worker

    Full Text Available Although often clinically indistinguishable in the early stages, Parkinson's disease (PD, Multiple System Atrophy (MSA and Progressive Supranuclear Palsy (PSP have distinct neuropathological changes. The aim of the current study was to identify white matter tract neurodegeneration characteristic of each of the three syndromes. Tract-based spatial statistics (TBSS was used to perform a whole-brain automated analysis of diffusion tensor imaging (DTI data to compare differences in fractional anisotropy (FA and mean diffusivity (MD between the three clinical groups and healthy control subjects. Further analyses were conducted to assess the relationship between these putative indices of white matter microstructure and clinical measures of disease severity and symptoms. In PSP, relative to controls, changes in DTI indices consistent with white matter tract degeneration were identified in the corpus callosum, corona radiata, corticospinal tract, superior longitudinal fasciculus, anterior thalamic radiation, superior cerebellar peduncle, medial lemniscus, retrolenticular and anterior limb of the internal capsule, cerebral peduncle and external capsule bilaterally, as well as the left posterior limb of the internal capsule and the right posterior thalamic radiation. MSA patients also displayed differences in the body of the corpus callosum corticospinal tract, cerebellar peduncle, medial lemniscus, anterior and superior corona radiata, posterior limb of the internal capsule external capsule and cerebral peduncle bilaterally, as well as the left anterior limb of the internal capsule and the left anterior thalamic radiation. No significant white matter abnormalities were observed in the PD group. Across groups, MD correlated positively with disease severity in all major white matter tracts. These results show widespread changes in white matter tracts in both PSP and MSA patients, even at a mid-point in the disease process, which are not found in patients

  1. Modelling of agricultural diffuse pollution and mitigation measures effectiveness in Wallonia (Belgium)

    Science.gov (United States)

    Sohier, C.; Deraedt, D.; Degré, A.

    2012-04-01

    Implementation of European directives in the environmental field and, specially, in the water management field, generates a request from policy-makers for news tools able to evaluate impact of management measures aiming at reducing pressures on ecosystems. In Wallonia (Southern Region of Belgium), the Nitrate Directive (EEC/676/91) was transposed into the "Walloon action plan for nitrogen sustainable management in agriculture" (PGDA1) in 2002. In 2007, a second plan was launched to reinforce some topics (PGDA2). Furthermore, the goal of "good quality" of surface waters and groundwater imposed by the Water Framework Directive poses new challenges in water management. In this context, a "soil and vadose" hydrological model is used in order to evaluate diffuse pollutions and efficiency of mitigation measures. This model, called EPICgrid, has been developed at catchment scale with an original modular concept on the basis of the field scale "water-soil-plant" EPIC model (Williams J.R., Jones C.A., Dyke P.T. (1984). A modelling approach to determining the relationship between erosion and soil productivity. Transactions of the ASAE. 27, 129-144). The model estimates, for each HRU identified into a 1km2 grid, water and nutrients flows into the plant-soil-vadose zone system (Sohier C., Degré A., Dautrebande S. (2009). From root zone modelling to regional forecasting of nitrate concentration in recharge flows - The case of the Walloon Region (Belgium). Journal of Hydrology, Volume 369, Issues 3-4, 15 May 2009, Pages 350-359). The model is used to make prospective simulations in order to evaluate the impact of measures currently performed to reduce the effect of diffuse pollution on water surface quality and groundwater quality, at regional scale. Response of the soil-vadose zone to agricultural practices modification is analyzed for the deadlines of the Water Framework Directive: 2015, 2021 and 2027, taking into account two climatic scenarios. Simulations results showed

  2. Simulation study on the measurements of diffusion coefficients in solid materials by short-lived radiotracer beams

    CERN Document Server

    Jeong, S C; Kawakami, H

    2003-01-01

    We have examined, by a computer simulation, an on-line measurement of diffusion coefficients by using a short-lived alpha particle emitter, sup 8 Li (half life of 0.84s), as a radiotracer. The energy spectra of alpha particles emitted from diffusing sup 8 Li primarily implanted in the sample of LiAl ar simulated as a measure of the diffusion of sup 8 Li in the sample. As a possible time sequence for the measurement, a time cycle of 6s, i.e. the implantation of sup 8 Li for 1.5s and subsequent diffusion for 4.5s, is supposed. The sample is primarily set on a given temperature for the measurement. The time-dependent yields of alpha particles during the time cycle reveal the possibility to measure the diffusion coefficient with an accuracy of 10% if larger than 1 x 10 sup - sup 9 cm sup 2 /s, by the comparison with the experimental spectra measured at the temperature, i.e. at a certain diffusion coefficient. (author)

  3. Measurement of diffuse photon-pairs density wave in a multiple-scattering medium.

    Science.gov (United States)

    Yu, Li-Ping; Chou, Chien; Wu, Jheng-Syong; Chan, Yi-Hsin

    2008-05-10

    As a continuation of the previously developed theory of a diffuse photon-pairs density wave (DPPDW) [Appl. Opt.44, 1416-1425 (2005)APOPAI0003-693510.1364/AO.44.001416], this research experimentally studies and verifies the DPPDW theory in a heterogeneous multiple-scattering medium. The DPPDW is generated by collecting the scattered linear polarized photon pairs (LPPPs) in the multiple-scattering medium. Theoretically, the common-path propagation of LPPPs not only provides common phase noise rejection mode but also performs coherence technique via heterodyne detection. In addition, the polarization gating and spatial coherence gating of LPPPs would suppress the severe scattered photon in the multiple-scattering medium. In the experiment, the amplitude and phase wavefronts of DPPDWs, which are distorted by a small object embedded in a homogeneous multiple-scattering medium, are measured in one dimension or two dimensions by scanning the source detector pair. The measured distortion of DPPDW wavefronts are detected precisely and are consistent with the theoretical calculation of DPPDW. It implies an improvement on the detection sensitivity of a small object compared with the conventional diffuse photon density wave (DPDW).

  4. Frequency-dependent photothermal measurement of transverse thermal diffusivity of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Brill, J. W.; Shahi, Maryam; Yao, Y. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Payne, Marcia M.; Anthony, J. E. [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Edberg, Jesper; Crispin, Xavier [Department of Science and Technology, Organic Electronics, Linköping University, SE-601 74 Norrköping (Sweden)

    2015-12-21

    We have used a photothermal technique, in which chopped light heats the front surface of a small (∼1 mm{sup 2}) sample and the chopping frequency dependence of thermal radiation from the back surface is measured with a liquid-nitrogen-cooled infrared detector. In our system, the sample is placed directly in front of the detector within its dewar. Because the detector is also sensitive to some of the incident light, which leaks around or through the sample, measurements are made for the detector signal that is in quadrature with the chopped light. Results are presented for layered crystals of semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pn) and for papers of cellulose nanofibrils coated with semiconducting poly(3,4-ethylene-dioxythiophene):poly(styrene-sulfonate) (NFC-PEDOT). For NFC-PEDOT, we have found that the transverse diffusivity, smaller than the in-plane value, varies inversely with thickness, suggesting that texturing of the papers varies with thickness. For TIPS-pn, we have found that the interlayer diffusivity is an order of magnitude larger than the in-plane value, consistent with previous estimates, suggesting that low-frequency optical phonons, presumably associated with librations in the TIPS side groups, carry most of the heat.

  5. Network analysis of surgical innovation: Measuring value and the virality of diffusion in robotic surgery.

    Science.gov (United States)

    Garas, George; Cingolani, Isabella; Panzarasa, Pietro; Darzi, Ara; Athanasiou, Thanos

    2017-01-01

    Existing surgical innovation frameworks suffer from a unifying limitation, their qualitative nature. A rigorous approach to measuring surgical innovation is needed that extends beyond detecting simply publication, citation, and patent counts and instead uncovers an implementation-based value from the structure of the entire adoption cascades produced over time by diffusion processes. Based on the principles of evidence-based medicine and existing surgical regulatory frameworks, the surgical innovation funnel is described. This illustrates the different stages through which innovation in surgery typically progresses. The aim is to propose a novel and quantitative network-based framework that will permit modeling and visualizing innovation diffusion cascades in surgery and measuring virality and value of innovations. Network analysis of constructed citation networks of all articles concerned with robotic surgery (n = 13,240, Scopus®) was performed (1974-2014). The virality of each cascade was measured as was innovation value (measured by the innovation index) derived from the evidence-based stage occupied by the corresponding seed article in the surgical innovation funnel. The network-based surgical innovation metrics were also validated against real world big data (National Inpatient Sample-NIS®). Rankings of surgical innovation across specialties by cascade size and structural virality (structural depth and width) were found to correlate closely with the ranking by innovation value (Spearman's rank correlation coefficient = 0.758 (p = 0.01), 0.782 (p = 0.008), 0.624 (p = 0.05), respectively) which in turn matches the ranking based on real world big data from the NIS® (Spearman's coefficient = 0.673;p = 0.033). Network analysis offers unique new opportunities for understanding, modeling and measuring surgical innovation, and ultimately for assessing and comparing generative value between different specialties. The novel surgical innovation metrics developed may

  6. Quantitative skin color measurements in acanthosis nigricans patients: colorimetry and diffuse reflectance spectroscopy.

    Science.gov (United States)

    Pattamadilok, Bensachee; Devpura, Suneetha; Syed, Zain U; Agbai, Oma N; Vemulapalli, Pranita; Henderson, Marsha; Rehse, Steven J; Mahmoud, Bassel H; Lim, Henry W; Naik, Ratna; Hamzavi, Iltefat H

    2012-08-01

    Tristimulus colorimetry and diffuse reflectance spectroscopy (DRS) are white-light skin reflectance techniques used to measure the intensity of skin pigmentation. The tristimulus colorimeter is an instrument that measures a perceived color and the DRS instrument measures biological chromophores of the skin, including oxy- and deoxyhemoglobin, melanin and scattering. Data gathered from these tools can be used to understand morphological changes induced in skin chromophores due to conditions of the skin or their treatments. The purpose of this study was to evaluate the use of these two instruments in color measurements of acanthosis nigricans (AN) lesions. Eight patients with hyperinsulinemia and clinically diagnosable AN were seen monthly. Skin pigmentation was measured at three sites: the inner forearm, the medial aspect of the posterior neck, and anterior neck unaffected by AN. Of the three, measured tristimulus L*a*b* color parameters, the luminosity parameter L* was found to most reliably distinguish lesion from normally pigmented skin. The DRS instrument was able to characterize a lesion on the basis of the calculated melanin concentration, though melanin is a weak indicator of skin change and not a reliable measure to be used independently. Calculated oxyhemoglobin and deoxyhemoglobin concentrations were not found to be reliable indicators of AN. Tristimulus colorimetry may provide reliable methods for respectively quantifying and characterizing the objective color change in AN, while DRS may be useful in characterizing changes in skin melanin content associated with this skin condition. © 2012 John Wiley & Sons A/S.

  7. Optical measurements of absorption changes in two-layered diffusive media

    Energy Technology Data Exchange (ETDEWEB)

    Fabbri, Francesco [Department of Biomedical Engineering, Bioengineering Center, Tufts University, 4 Colby Street, Medford, MA 02155 (United States); Sassaroli, Angelo [Department of Biomedical Engineering, Bioengineering Center, Tufts University, 4 Colby Street, Medford, MA 02155 (United States); Henry, Michael E [McLean Hospital and Department of Psychiatry, Harvard Medical School, 115 Mill Street, Belmont, MA 02478 (United States); Fantini, Sergio [Department of Biomedical Engineering, Bioengineering Center, Tufts University, 4 Colby Street, Medford, MA 02155 (United States)

    2004-04-07

    We have used Monte Carlo simulations for a two-layered diffusive medium to investigate the effect of a superficial layer on the measurement of absorption variations from optical diffuse reflectance data processed by using: (a) a multidistance, frequency-domain method based on diffusion theory for a semi-infinite homogeneous medium; (b) a differential-pathlength-factor method based on a modified Lambert-Beer law for a homogeneous medium and (c) a two-distance, partial-pathlength method based on a modified Lambert-Beer law for a two-layered medium. Methods (a) and (b) lead to a single value for the absorption variation, whereas method (c) yields absorption variations for each layer. In the simulations, the optical coefficients of the medium were representative of those of biological tissue in the near-infrared. The thickness of the first layer was in the range 0.3-1.4 cm, and the source-detector distances were in the range 1-5 cm, which is typical of near-infrared diffuse reflectance measurements in tissue. The simulations have shown that (1) method (a) is mostly sensitive to absorption changes in the underlying layer, provided that the thickness of the superficial layer is {approx}0.6 cm or less; (2) method (b) is significantly affected by absorption changes in the superficial layer and (3) method (c) yields the absorption changes for both layers with a relatively good accuracy of {approx}4% for the superficial layer and {approx}10% for the underlying layer (provided that the absorption changes are less than 20-30% of the baseline value). We have applied all three methods of data analysis to near-infrared data collected on the forehead of a human subject during electroconvulsive therapy. Our results suggest that the multidistance method (a) and the two-distance partial-pathlength method (c) may better decouple the contributions to the optical signals that originate in deeper tissue (brain) from those that originate in more superficial tissue layers.

  8. An objective measure for the sensitivity of room impulse response and its link to a diffuse sound field

    DEFF Research Database (Denmark)

    Prislan, Rok; Brunskog, Jonas; Jacobsen, Finn

    2014-01-01

    - sequently examined experimentally. The sensitivity of a room due to changes in the initial condi- tions is quantified by measuring a pair of impulse responses in a room differing only in the sound source position. Such changes are linked to mixing and the diffuse sound field. The measure is based......This study is relevant to acoustic measurements in reverberation rooms such as measurements of sound transmission, sound absorption, and sound power levels of noise sources. The study presents a quantitative measure for the diffuseness in a room, which is first introduced theoretically and sub...

  9. A technique for measuring oxygen saturation in biological tissues based on diffuse optical spectroscopy

    Science.gov (United States)

    Kleshnin, Mikhail; Orlova, Anna; Kirillin, Mikhail; Golubiatnikov, German; Turchin, Ilya

    2017-07-01

    A new approach to optical measuring blood oxygen saturation was developed and implemented. This technique is based on an original three-stage algorithm for reconstructing the relative concentration of biological chromophores (hemoglobin, water, lipids) from the measured spectra of diffusely scattered light at different distances from the probing radiation source. The numerical experiments and approbation of the proposed technique on a biological phantom have shown the high reconstruction accuracy and the possibility of correct calculation of hemoglobin oxygenation in the presence of additive noise and calibration errors. The obtained results of animal studies have agreed with the previously published results of other research groups and demonstrated the possibility to apply the developed technique to monitor oxygen saturation in tumor tissue.

  10. Permeation measurement of gestodene for some biodegradable materials using Franz diffusion cells.

    Science.gov (United States)

    Liu, Danhua; Zhang, Chong; Zhang, Xiaowei; Zhen, Zhu; Wang, Ping; Li, Jianxin; Yi, Dongxu; Jin, Ying; Yang, Dan

    2015-09-01

    Biodegradable poly(d,l-lactide) (PDLLA), Poly(trimethylene carbonate) (PTMC), polycaprolactone (PCL), poly(caprolactone-co-d,l-lactide) (PCDLLA) and poly(trimethylene carbonate-co-caprolactone) (PTCL) are recently used for clinical drug delivery system such as subcutaneous contraceptive implant capsule due to their biodegradable properties that they could possess long-term stable performance in vivo without removal, however their permeation rate is unknown. In the work, biodegradable material membranes were prepared by solvent evaporation using chloroform, and commercial silicone rubber membrane served as a control. Gestodene was used as a model drug. Gestodene has high biologic progestational activity which allows for high contraceptive reliability at very low-dose levels. The permeation rate of gestodene for several biodegradable materials was evaluated. In vitro diffusion studies were done using Franz diffusion cells with a diffusion area of 1.33 cm(2). Phosphate buffer solution (PBS, pH 7.4), 10% methanol solution and distilled water were taken in donor and receiver chambers at temperature of 37 °C respectively. The in vitro experiments were conducted over a period of 24 h during which samples were collected at regular intervals. The withdrawn samples were appropriately diluted and measured on UV-vis spectrophotometer at 247 nm. Conclusion data from our study showed that permeation rate of PCDLLA with CL ratio more than 70% could be more excellent than commercial silicone rubber membrane. They may be suitable as a candidate carrier for gestodene subcutaneous contraceptive implants in contraceptive fields.

  11. An objective measure for the sensitivity of room impulse response and its link to a diffuse sound field.

    Science.gov (United States)

    Prislan, Rok; Brunskog, Jonas; Jacobsen, Finn; Jeong, Cheol-Ho

    2014-10-01

    This study is relevant to acoustic measurements in reverberation rooms such as measurements of sound transmission, sound absorption, and sound power levels of noise sources. The study presents a quantitative measure for the diffuseness in a room, which is first introduced theoretically and subsequently examined experimentally. The sensitivity of a room due to changes in the initial conditions is quantified by measuring a pair of impulse responses in a room differing only in the sound source position. Such changes are linked to mixing and the diffuse sound field. The measure is based on the maximum of the absolute value of the cross-correlation between the time windowed sections of the two impulse responses. By integrating this quantity normalized by the energy of the impulse response of the room, a single number rating is obtained. Results based on three sets of experiments indicate that the diffusers and absorbers in the room influence the proposed sensitivity measures systematically.

  12. Measurement and Computation of Supersonic Flow in a Lobed Diffuser-Mixer for Trapped Vortex Combustors

    Science.gov (United States)

    Brankovic, Andreja; Ryder, Robert C., Jr.; Hendricks, Robert C.; Liu, Nan-Suey; Gallagher, John R.; Shouse, Dale T.; Roquemore, W. Melvyn; Cooper, Clayton S.; Burrus, David L.; Hendricks, John A.

    2002-01-01

    The trapped vortex combustor (TVC) pioneered by Air Force Research Laboratories (AFRL) is under consideration as an alternative to conventional gas turbine combustors. The TVC has demonstrated excellent operational characteristics such as high combustion efficiency, low NO(x) emissions, effective flame stabilization, excellent high-altitude relight capability, and operation in the lean-burn or rich burn-quick quench-lean burn (RQL) modes of combustion. It also has excellent potential for lowering the engine combustor weight. This performance at low to moderate combustor mach numbers has stimulated interest in its ability to operate at higher combustion mach number, and for aerospace, this implies potentially higher flight mach numbers. To this end, a lobed diffuser-mixer that enhances the fuel-air mixing in the TVC combustor core was designed and evaluated, with special attention paid to the potential shock system entering the combustor core. For the present investigation, the lobed diffuser-mixer combustor rig is in a full annular configuration featuring sixfold symmetry among the lobes, symmetry within each lobe, and plain parallel, symmetric incident flow. During hardware cold-flow testing, significant discrepancies were found between computed and measured values for the pitot-probe-averaged static pressure profiles at the lobe exit plane. Computational fluid dynamics (CFD) simulations were initiated to determine whether the static pressure probe was causing high local flow-field disturbances in the supersonic flow exiting the diffuser-mixer and whether shock wave impingement on the pitot probe tip, pressure ports, or surface was the cause of the discrepancies. Simulations were performed with and without the pitot probe present in the modeling. A comparison of static pressure profiles without the probe showed that static pressure was off by nearly a factor of 2 over much of the radial profile, even when taking into account potential axial displacement of the

  13. Gold nanorods based diffusion reflection measurements: current status and perspectives for clinical applications

    Science.gov (United States)

    Ankri, Rinat; Fixler, Dror

    2017-07-01

    Optical imaging is a powerful tool for investigating the structure and function of tissues. Tissue optical imaging technologies are generally discussed under two broad regimes: microscopic and macroscopic, while the latter is widely investigated in the field of light-tissue interaction. Among the developed optical technologies for tissue investigation, the diffusion reflectance (DR) method is a simple and safe technology. However, this method suffers from low specificity and low signal-to-noise ratio, so the extraction of the tissue properties is not an easy task. In this review, we describe the use of gold nanorods (GNRs) in DR spectroscopy. The GNRs present unique optical properties which enhance the scattering and absorption properties of a tissue. The GNRs can be easily targeted toward abnormal sites in order to improve the DR signal and to distinguish between the healthy and the abnormal sites in the tissue, with high specificity. This article describes the use of the DR-GNRs method for the detection of cancer and atherosclerosis, from light transfer theory, through the extraction of the tissue properties using the diffusion theory and up to DR in vivo measurements.

  14. Quantitative diffusion and swelling kinetic measurements using large-angle interferometric refractometry.

    Science.gov (United States)

    Saunders, John E; Chen, Hao; Brauer, Chris; Clayton, McGregor; Chen, Weijian; Barnes, Jack A; Loock, Hans-Peter

    2015-12-07

    The uptake and release of sorbates into films and coatings is typically accompanied by changes of the films' refractive index and thickness. We provide a comprehensive model to calculate the concentration of the sorbate from the average refractive index and the film thickness, and validate the model experimentally. The mass fraction of the analyte partitioned into a film is described quantitatively by the Lorentz-Lorenz equation and the Clausius-Mosotti equation. To validate the model, the uptake kinetics of water and other solvents into SU-8 films (d = 40-45 μm) were explored. Large-angle interferometric refractometry measurements can be used to characterize films that are between 15 μm to 150 μm thick and, Fourier analysis, is used to determine independently the thickness, the average refractive index and the refractive index at the film-substrate interface at one-second time intervals. From these values the mass fraction of water in SU-8 was calculated. The kinetics were best described by two independent uptake processes having different rates. Each process followed one-dimensional Fickian diffusion kinetics with diffusion coefficients for water into SU-8 photoresist film of 5.67 × 10(-9) cm(2) s(-1) and 61.2 × 10(-9) cm(2) s(-1).

  15. Diffusion of CO2 in n-hexadecane determined from NMR relaxometry measurements

    Science.gov (United States)

    Hao, Min; Song, Yongchen; Su, Bo; Zhao, Yuechao

    2015-06-01

    In this study, we discuss the feasibility in computation of diffusion coefficient (D) using the longitudinal relaxation time T1. CO2-n-hexadecane in pure solutions and in a porous medium was tested separately by measuring the T1 of n-hexadecane at varying CO2 concentration (c). The relationship between T1 and c was correlated. The results show that T1 exponentially rises with the increase of c. Thus, we proposed the method to estimate D of CO2 using T1 through the relationship above and Fick's law. We computed D from T1 and compared this method with the traditional method. The two methods agree well with differences less than 10%. The new method is characterized by simpleness, convenience and flexibility, as it computes D with the only requirement of monitoring T1. This new method will guide the use of nuclear magnetic resonance logging in in-field testing of CO2 diffusion and migration laws.

  16. Thermal-Diffusivity Measurements of Mexican Citrus Essential Oils Using Photoacoustic Methodology in the Transmission Configuration

    Science.gov (United States)

    Muñoz, G. A. López; González, R. F. López; López, J. A. Balderas; Martínez-Pérez, L.

    2011-05-01

    Photoacoustic methodology in the transmission configuration (PMTC) was used to study the thermophysical properties and their relation with the composition in Mexican citrus essential oils providing the viability of using photothermal techniques for quality control and for authentication of oils and their adulteration. Linear relations for the amplitude (on a semi-log scale) and phase, as functions of the sample's thickness, for the PMTC was obtained through a theoretical model fit to the experimental data for thermal-diffusivity measurements in Mexican orange, pink grapefruit, mandarin, lime type A, centrifuged essential oils, and Mexican distilled lime essential oil. Gas chromatography for distilled lime essential oil and centrifuged lime essential oil type A is reported to complement the study. Experimental results showed close thermal-diffusivity values between Mexican citrus essential oils obtained by centrifugation, but a significant difference of this physical property for distilled lime oil and the corresponding value obtained by centrifugation, which is due to their different chemical compositions involved with the extraction processes.

  17. Lateral diffusion of PEG-Lipid in magnetically aligned bicelles measured using stimulated echo pulsed field gradient 1H NMR.

    Science.gov (United States)

    Soong, Ronald; Macdonald, Peter M

    2005-01-01

    Lateral diffusion measurements of PEG-lipid incorporated into magnetically aligned bicelles are demonstrated using stimulated echo (STE) pulsed field gradient (PFG) proton (1H) nuclear magnetic resonance (NMR) spectroscopy. Bicelles were composed of dimyristoyl phosphatidylcholine (DMPC) plus dihexanoyl phosphatidylcholine (DHPC) (q = DMPC/DHPC molar ratio = 4.5) plus 1 mol % (relative to DMPC) dimyristoyl phosphatidylethanolamine-N-[methoxy(polyethylene glycol)-2000] (DMPE-PEG 2000) at 25 wt % lipid. 1H NMR STE spectra of perpendicular aligned bicelles contained only resonances assigned to residual HDO and to overlapping contributions from a DMPE-PEG 2000 ethoxy headgroup plus DHPC choline methyl protons. Decay of the latter's STE intensity in the STE PFG 1H NMR experiment (g(z) = 244 G cm(-1)) yielded a DMPE-PEG 2000 (1 mol %, 35 degrees C) lateral diffusion coefficient D = 1.35 x 10(-11) m2 s(-1). Hence, below the "mushroom-to-brush" transition, DMPE-PEG 2000 lateral diffusion is dictated by its DMPE hydrophobic anchor. D was independent of the diffusion time, indicating unrestricted lateral diffusion over root mean-square diffusion distances of microns, supporting the "perforated lamellae" model of bicelle structure under these conditions. Overall, the results demonstrate the feasibility of lateral diffusion measurements in magnetically aligned bicelles using the STE PFG NMR technique.

  18. Accuracy of apparent diffusion coefficient value measurement on PACS workstation: A comparative analysis.

    Science.gov (United States)

    El Kady, Reem M; Choudhary, Arabinda Kumar; Tappouni, Rafel

    2011-03-01

    The purpose of this article is to evaluate the accuracy of apparent diffusion coefficient (ADC) measurements made with a PACS workstation compared with measurements made with a dedicated workstation, which is currently considered the reference standard. A retrospective review was performed in liver lesions from 79 patients using three MRI platforms. The final diagnosis was established by liver biopsy in 31 patients and by dynamic MRI and follow-up, both clinical and radiologic as indicated, in 48 patients. Each lesion that was clearly demonstrable on the ADC map was measured with a commercial dedicated postprocessing workstation and again with a PACS system. A two-sample t test was used to determine the statistically significant differences between the two ADC measurements. A total of 79 patients with 120 liver lesions were included. ADC values measured on the workstation were 0.4-4.38 × 10(-3) mm(2)/s. The ADC values measured on the PACS were 0.42-4.35 × 10(-3) mm(2)/s. The T value was -1.113, with 119 degrees of freedom, and the significance level was 0.268, which implies no significant difference between the two different measuring systems for all pathologic abnormalities and MRI scanners used. ADC values measured on a routine PACS workstation are as accurate as the values obtained on a dedicated specialized workstation. ADC value measurement on the routine PACS will save time and lead to increased utilization, which, in turn, will lead to an improved understanding of the different disease processes and their clinical management.

  19. Elimination of single-beam substitution error in diffuse reflectance measurements using an integrating sphere

    Science.gov (United States)

    Vidovič, Luka; Majaron, Boris

    2013-03-01

    Diffuse reflectance spectra (DRS) of biological samples are commonly measured using an integrating sphere (IS), in which spectrally broad illumination light is multiply scattered and homogenized. The measurement begins by placing a highly reflective white standard against the IS sample opening and collecting the reflected light at the signal output port to account for illumination field. After replacing the white standard with test sample of interest, DRS of the latter is determined as the ratio of the two values at each involved wavelength. However, because test samples are invariably less reflective than the white standard, such a substitution modifies the illumination field inside the IS. This leads to underestimation of the sample's reflectivity and distortion of measured DRS, which is known as single-beam substitution error (SBSE). Barring the use of much more complex dual-beam experimental setups, involving dedicated IS, literature states that only approximate corrections of SBSE are possible, e.g., by using look-up tables generated with calibrated low-reflectivity standards. We present a practical way to eliminate the SBSE using IS equipped with an additional "reference" output port. Two additional measurements performed at this port (of the white standard and sample, respectively) namely enable an accurate compensation for above described alteration of the illumination field. In addition, we analyze the dependency of SBSE on sample reflectivity and illustrate its impact on measurements of DRS in human skin with a typical IS.

  20. Antibodies to the pneumococcal surface protein A, PspA, can be produced in splenectomized and can protect splenectomized mice from infection with Streptococcus pneumoniae.

    Science.gov (United States)

    Coats, Mamie T; Benjamin, W H; Hollingshead, S K; Briles, D E

    2005-07-21

    Asplenic individuals have increased susceptibility to septicemia caused by encapsulated bacteria. Streptococcus pneumoniae, a pathogen carried in the nasal passages of many humans without complication, is responsible for a large proportion of infections seen in asplenic individuals. Our studies have evaluated the efficacy of antibodies to pneumococcal surface protein A (PspA) in protection of asplenic mice. In passive immunity studies, pneumococci were more completely cleared from the blood of splenectomized mice receiving passive antiserum to PspA than those receiving normal rabbit serum. From active mucosal (intranasal) and systemic (subcutaneous) immunizations with rPspA, we determined that the levels of PspA antibodies produced in splenectomized mice were not significantly different from levels seen in mock-splenectomized animals. This active immunity to PspA was able to protect splenectomized mice against death following infection with live pneumococci. Our results suggest that PspA immunization may also protect asplenic humans from pneumococcal infections.

  1. A Bibliography of the Personal Software Process (PSP) and the Team Software Process (TSP)

    Science.gov (United States)

    2009-10-01

    IEEE Computer Society Press, 1996. http://www.computer.org/portal/web/csdl/doi/10.1109/CSEE.1996.491362 El Emam, K.; Shostak, B .; & Madhavji, N... Marciniak Editor-in-Chief, New York, NY: John Wiley & Sons, 1994, 851-860. Humphrey, Watts S. ―Reflections on a Software Life,‖ In the Beginning...Adoption with PSP/TSP— TCAIM.‖ Proceedings of the TSP Symposium (September 2008). http://www.sei.cmu.edu/tspsymposium/ Nichols, B . & Willett, Alan

  2. Evaluation of policy measures and methods to reduce diffuse water pollution

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Ute; Doehler, Helmut; Eurich-Menden, Brigitte; Goemann, Horst; Jaeger, Peter; Kreins, Peter; Moeller, Christine; Prigge, Achim; Ristenpart, Erik; Schultheiss, Ute

    2006-11-15

    After considerable improvements of wastewater treatment, the loads of nutrients and plant protection agents, deriving from agriculture and heavy metals from urban drainages effluents as well as from erosion of agricultural soils are the main sources of nutrients and harmful substances in the loads of water bodies. The targets of the project were on the one hand the analysis of the political and legislative framework of both policy fields and on the other hand the evaluation of several, selected water protection measures with regard to their contribution to reduce water pollution, their economical effects as well as their political enforceability. The focus was laid on diffuse water pollution caused by agriculture. As main reasons for the diffuse water pollution stagnating at high level, the analysis of the political framework identified a lack of implementation discipline of water law, followed by the fragmented and insufficient water protection legislation itself and the previous design of the common agricultural policy slanted towards increasing productivity. For the future co-operation of agricultural and water authorities in implementation of their reforms and better definition of 'Good Farming Practice' are recommended. The second investigation level focuses on the analysis and assessment of selected measures to reduce the input of nutrients and plant protection agents. This part was done with help of calculation models focussing on the specific cost/benefit ratios for water protection. In detail the following measures have been analysed: decoupling of direct payments, coupling of livestock farming to areas, tax on mineral nitrogen, pesticide levy, buffer stripes alongside of watercourses, all season crop cover on arable land, soil cultivation procedures, changing the use of arable land, optimisation of animal nutrition, optimisation of manure storage and application, co-operative agreements, education and training. Co-operations and water protection

  3. Time-Resolved Phosphorescence Anisotropy For Measuring Slow Rotational Diffusion In The Erythrocyte Cytoskeleton

    Science.gov (United States)

    Woodhouse, A. G.; Czarnecki, J. J.; Blatt, E.; Sawyer, W. H.

    1988-06-01

    The cytoskeletal architecture of a cell controls many cell processes and characteristics (cell shape, motility, endocytosis, cell division, organelle position and movement). Many of these processes involve the assembly and disassembly of cytoskeletal elements, but the highly cross-linked polymer system must, of necessity, possess flexibility and motional freedom. Components of the erythrocyte cytoskeleton (actin, spectrin and band 4.1) may be reconstituted into a ternary complex which forms a viscous cross-linked gel. It is unlikely that this structure is identical to that existing in vivo, however, it does provide a convenient experimental model system in which the rotational motion of the individual components may be studied. We have examined this system using time-resolved phosphorescence anisotropy which measures rotational diffusion in the microsecond to millisecond time window.

  4. Influence of probe pressure on diffuse reflectance spectra of human skin measured in vivo.

    Science.gov (United States)

    Popov, Alexey P; Bykov, Alexander V; Meglinski, Igor V

    2017-11-01

    Mechanical pressure superficially applied on the human skin surface by a fiber-optic probe influences the spatial distribution of blood within the cutaneous tissues. Upon gradual load of weight on the probe, a stepwise increase in the skin reflectance spectra is observed. The decrease in the load follows the similar inverse staircase-like tendency. The observed stepwise reflectance spectra changes are due to, respectively, sequential extrusion of blood from the topical cutaneous vascular beds and their filling afterward. The obtained results are confirmed by Monte Carlo modeling. This implies that pressure-induced influence during the human skin diffuse reflectance spectra measurements in vivo should be taken into consideration, in particular, in the rapidly developing area of wearable gadgets for real-time monitoring of various human body parameters. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  5. Real space mapping of oxygen vacancy diffusion and electrochemical transformations by hysteretic current reversal curve measurements

    Science.gov (United States)

    Kalinin, Sergei V.; Balke, Nina; Borisevich, Albina Y.; Jesse, Stephen; Maksymovych, Petro; Kim, Yunseok; Strelcov, Evgheni

    2014-06-10

    An excitation voltage biases an ionic conducting material sample over a nanoscale grid. The bias sweeps a modulated voltage with increasing maximal amplitudes. A current response is measured at grid locations. Current response reversal curves are mapped over maximal amplitudes of the bias cycles. Reversal curves are averaged over the grid for each bias cycle and mapped over maximal bias amplitudes for each bias cycle. Average reversal curve areas are mapped over maximal amplitudes of the bias cycles. Thresholds are determined for onset and ending of electrochemical activity. A predetermined number of bias sweeps may vary in frequency where each sweep has a constant number of cycles and reversal response curves may indicate ionic diffusion kinetics.

  6. Spin diffusion in bulk GaN measured with MnAs spin injector

    KAUST Repository

    Jahangir, Shafat

    2012-07-16

    Spin injection and precession in bulk wurtzite n-GaN with different doping densities are demonstrated with a ferromagnetic MnAs contact using the three-terminal Hanle measurement technique. Theoretical analysis using minimum fitting parameters indicates that the spin accumulation is primarily in the n-GaN channel rather than at the ferromagnet (FM)/semiconductor (SC) interface states. Spin relaxation in GaN is interpreted in terms of the D’yakonov-Perel mechanism, yielding a maximum spin lifetime of 44 ps and a spin diffusion length of 175 nm at room temperature. Our results indicate that epitaxial ferromagnetic MnAs is a suitable high-temperature spin injector for GaN.

  7. Experimental estimation of the photons visiting probability profiles in time-resolved diffuse reflectance measurement.

    Science.gov (United States)

    Sawosz, P; Kacprzak, M; Weigl, W; Borowska-Solonynko, A; Krajewski, P; Zolek, N; Ciszek, B; Maniewski, R; Liebert, A

    2012-12-07

    A time-gated intensified CCD camera was applied for time-resolved imaging of light penetrating in an optically turbid medium. Spatial distributions of light penetration probability in the plane perpendicular to the axes of the source and the detector were determined at different source positions. Furthermore, visiting probability profiles of diffuse reflectance measurement were obtained by the convolution of the light penetration distributions recorded at different source positions. Experiments were carried out on homogeneous phantoms, more realistic two-layered tissue phantoms based on the human skull filled with Intralipid-ink solution and on cadavers. It was noted that the photons visiting probability profiles depend strongly on the source-detector separation, the delay between the laser pulse and the photons collection window and the complex tissue composition of the human head.

  8. SPME-Based Ca-History Method for Measuring SVOC Diffusion Coefficients in Clothing Material.

    Science.gov (United States)

    Cao, Jianping; Liu, Ningrui; Zhang, Yinping

    2017-08-15

    Clothes play an important role in dermal exposure to indoor semivolatile organic compounds (SVOCs). The diffusion coefficient of SVOCs in clothing material (Dm) is essential for estimating SVOC sorption by clothing material and subsequent dermal exposure to SVOCs. However, few studies have reported the measured Dm for clothing materials. In this paper, we present the solid-phase microextraction (SPME) based Ca-history method. To the best of our knowledge, this is the first try to measure Dm with known relative standard deviation (RSD). A thin sealed chamber is formed by a circular ring and two pieces of flat SVOC source materials that are tightly covered by the targeted clothing materials. Dm is obtained by applying an SVOC mass transfer model in the chamber to the history of gas-phase SVOC concentrations (Ca) in the chamber measured by SPME. Dm's of three SVOCs, di-iso-butyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and tris(1-chloro-2-propyl) phosphate (TCPP), in a cotton T-shirt can be obtained within 16 days, with RSD less than 3%. This study should prove useful for measuring SVOC Dm in various sink materials. Further studies are expected to facilitate application of this method and investigate the effects of temperature, relative humidity, and clothing material on Dm.

  9. Vertical-type chiroptical spectrophotometer (I): instrumentation and application to diffuse reflectance circular dichroism measurement.

    Science.gov (United States)

    Harada, Takunori; Hayakawa, Hiroshi; Kuroda, Reiko

    2008-07-01

    We have designed and built a novel universal chiroptical spectrophotometer (UCS-2: J-800KCMF), which can carry out in situ chirality measurement of solid samples without any pretreatment, in the UV-vis region and with high relative efficiency. The instrument was designed to carry out transmittance and diffuse reflectance (DR) circular dichroism (CD) measurements simultaneously, thus housing two photomultipliers. It has a unique feature that light impinges on samples vertically so that loose powders can be measured by placing them on a flat sample holder in an integrating sphere. As is our first universal chiroptical spectrophotometer, UCS-1, two lock-in amplifiers are installed to remove artifact signals arising from macroscopic anisotropies which are unique to solid samples. High performance was achieved by theoretically analyzing and experimentally proven the effect of the photoelastic modulator position on the CD base line shifts, and by selecting high-quality optical and electric components. Measurement of microcrystallines of both enantiomers of ammonium camphorsulfonate by the DRCD mode gave reasonable results.

  10. Stability of the cargo regions of the cfr-carrying, multiresistance plasmid pSP01 from Staphylococcus epidermidis.

    Science.gov (United States)

    Brenciani, Andrea; Morroni, Gianluca; Mingoia, Marina; Varaldo, Pietro E; Giovanetti, Eleonora

    2016-12-01

    This study investigated the stability or instability - i.e. the ability or inability to undergo excision in circular form - of the four cargo regions (cr1 to cr4) of the novel cfr-carrying, multiresistance plasmid pSP01, arboured by a clinical Staphylococcus epidermidis isolate. Only cr4 proved unstable. The stability of cr1 and cr2 was substantially expected. Insertion sequences (ISs) played an important role in the stability of cr3 (the cfr gene context) and in the instability of cr4. Whereas the stability of cfr genetic contexts is associated with the presence of a single IS copy (istAS-istBS in cr3), their instability is associated with two identical, flanking ISs with the same orientation. cr4 is bracketed between two identical IS257 elements, and appears to behave as a composite transposon. Its instability is of interest because of the existence of a closely related cfr plasmid from S. epidermidis (pSP01.1) that differs from pSP01 only by the lack of cr4. An integration/recombination mechanism is suggested to explain how cr4 may have moved to pSP01.1 to form pSP01. Copyright © 2016 Elsevier GmbH. All rights reserved.

  11. Removal of the phage-shock protein PspB causes reduction of virulence in Salmonella enterica serovar Typhimurium independently of NRAMP1

    DEFF Research Database (Denmark)

    Wallrodt, Inke; Jelsbak, Lotte; Thomsen, Line E.

    2014-01-01

    . In Salmonella enterica serovar Typhimurium (S. Typhimurium), it has recently been reported that PspA is essential for systemic infection of mice, but only in NRAMP1(+) mice, signifying that attenuation is related to coping with divalent cation starvation in the intracellular environment. In the present study......IV-induced secretin stress. In conclusion, our results demonstrate that removal of PspB reduces virulence in S. Typhimurium independently of host NRAMP1 expression, demonstrating that PspB has roles in intra-host survival distinct from the reported contributions of PspA....

  12. Mucosal immunization with PspA (Pneumococcal surface protein A-adsorbed nanoparticles targeting the lungs for protection against pneumococcal infection.

    Directory of Open Access Journals (Sweden)

    Tasson C Rodrigues

    Full Text Available Burden of pneumonia caused by Streptococcus pneumoniae remains high despite the availability of conjugate vaccines. Mucosal immunization targeting the lungs is an attractive alternative for the induction of local immune responses to improve protection against pneumonia. Our group had previously described the development of poly(glycerol adipate-co-ω-pentadecalactone (PGA-co-PDL polymeric nanoparticles (NPs adsorbed with Pneumococcal surface protein A from clade 4 (PspA4Pro within L-leucine microcarriers (nanocomposite microparticles-NCMPs for mucosal delivery targeting the lungs (NP/NCMP PspA4Pro. NP/NCMP PspA4Pro was now used for immunization of mice. Inoculation of this formulation induced anti-PspA4Pro IgG antibodies in serum and lungs. Analysis of binding of serum IgG to intact bacteria showed efficient binding to bacteria expressing PspA from clades 3, 4 and 5 (family 2, but no binding to bacteria expressing PspA from clades 1 and 2 (family 1 was observed. Both mucosal immunization with NP/NCMP PspA4Pro and subcutaneous injection of the protein elicited partial protection against intranasal lethal pneumococcal challenge with a serotype 3 strain expressing PspA from clade 5 (PspA5. Although similar survival levels were observed for mucosal immunization with NP/NCMP PspA4Pro and subcutaneous immunization with purified protein, NP/NCMP PspA4Pro induced earlier control of the infection. Conversely, neither immunization with NP/NCMP PspA4Pro nor subcutaneous immunization with purified protein reduced bacterial burden in the lungs after challenge with a serotype 19F strain expressing PspA from clade 1 (PspA1. Mucosal immunization with NP/NCMP PspA4Pro targeting the lungs is thus able to induce local and systemic antibodies, conferring protection only against a strain expressing PspA from the homologous family 2.

  13. Overexpression of PSP1 enhances growth of transgenic Arabidopsis plants under ambient air conditions.

    Science.gov (United States)

    Han, Xiaofang; Peng, Keli; Wu, Haixia; Song, Shanshan; Zhu, Yerong; Bai, Yanling; Wang, Yong

    2017-07-01

    The importance of the phosphorylated pathway (PPSB) of L-serine (Ser) biosynthesis in plant growth and development has been demonstrated, but its specific role in leaves and interaction with photorespiration, the main leaf Ser biosynthetic pathway at daytime, are still unclear. To investigate whether changes in biosynthesis of Ser by the PPSB in leaves could have an impact on photorespiration and plant growth, we overexpressed PSP1, the last enzyme of this pathway, under control of the Cauliflower Mosaic Virus 35S promoter in Arabidopsis thaliana. Overexpressor plants grown in normal air displayed larger rosette diameter and leaf area as well as higher fresh and dry weight than the wild type. By contrast, no statistically significant differences to the wild type were observed when the overexpressor seedlings were transferred to elevated CO2, indicating a relationship between PSP1 overexpression and photorespiration. Additionally, the transgenic plants displayed higher photorespiration, an increase in CO2 net-uptake and stronger expression in the light of genes encoding enzymes involved in photorespiration. We further demonstrated that expression of many genes involved in nitrogen assimilation was also promoted in leaves of transgenic plants and that leaf nitrate reductase activity increased in the light, too, although not in the dark. Our results suggest a close correlation between the function of PPSB and photorespiration, and also nitrogen metabolism in leaves.

  14. Application of Shear Plate Interferometry to Jet Diffusion Flame Temperature Measurements

    Science.gov (United States)

    VanDerWege, Brad A.; OBrien, Chris J.; Hochgreb, Simone

    1997-01-01

    The recent ban on the production of bromotrifluoromethane (CF3Br) because of its high stratospheric ozone depletion potential has led to interest in finding alternative agents for fire extinguishing applications. Some of the promising alternatives are fluorinated hydrocarbons. A clear understanding of the effects of CF3Br and alternative chemical suppressants on diffusion flames is therefore necessary in the selection of alternative suppressants for use in normal and microgravity. The flame inhibition effects of halogen compounds have been studied extensively in premixed systems. The effect of addition of halocarbons (carbon-halogen compounds) to diffusion flames has been studied experimentally in coflow configurations and in counterflow gaseous and liquid-pool flames. Halogenated compounds are believed to inhibit combustion by scavenging hydrogen radicals to form the relatively unreactive compound HF, or through a catalytic recombination cycle involving HBr to form H2. Comparisons between halogens show that bromine inhibition is significantly more effective than chlorine or fluorine. Although fluorinated compounds are only slightly more effective inhibitors on a mass basis than nitrogen, they are more effective on a volume basis and are easily stored in liquid form. The objectives of this study are (a) to determine the stability limits of laminar jet diffusion flames with respect to inhibitor concentration in both normal and microgravity, and (b) to investigate the structure of halocarbon-inhibited flames. In the initial phase of this project, visual diagnostics were used to observe the structure and behavior of normal and microgravity flames. The initial observations showed significant changes in the structure of the flames with the addition of halocarbons to the surrounding environment, as discussed below. Furthermore, the study established that the flames are more stable relative to the addition of halocarbons in microgravity than in normal gravity. Visual

  15. In situ lithium diffusion measurement in solid ionic conductors using short-lived radiotracer beam of {sup 8}Li

    Energy Technology Data Exchange (ETDEWEB)

    Ishiyama, H. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Jeong, S.C., E-mail: sunchan.jeong@kek.jp [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Watanabe, Y.X.; Hirayama, Y.; Imai, N.; Miyatake, H.; Oyaizu, M. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Osa, A.; Otokawa, Y.; Matsuda, M.; Nishio, K.; Makii, H.; Sato, T.K. [Japan Atomic Energy Agency (JAEA), Shirane 2-4, Tokai, Ibaraki 319-1195 (Japan); Kuwata, N.; Kawamura, J. [Institute of Multidisciplinary Research for Advance Materials, Tohoku University, Sendai 980-8577 (Japan); Nakao, A.; Ueno, H. [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Kim, Y.H. [Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-747 (Korea, Republic of); Kimura, S.; Mukai, M. [University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)

    2015-07-01

    We developed an in situ radiotracer method for diffusion studies in solids using short-lived α-emitting {sup 8}Li tracer. In the method, while implanting a pulsed {sup 8}Li beam into a solid material of interest, the α particles emitted into the implantation side of the sample surface were detected as a function of time. By changing the implantation depth and the detection angle against the sample surface according to lithium diffusivity (deep implantation and large angle with a large solid angle, or shallow implantation and small angle with a narrow solid angle), the method can be sensitive to a wide range of diffusion length ranging from micrometer scale to nanometer scale per second. The feasibility of the method was demonstrated by measuring the lithium diffusion coefficients to the order of 10{sup −12} cm{sup 2}/s in lithium ionic conductors.

  16. Methods for quantitative infrared directional-hemispherical and diffuse reflectance measurements using an FTIR and a commercial integrating sphere

    Energy Technology Data Exchange (ETDEWEB)

    Blake, Thomas A.; Johnson, Timothy J.; Tonkyn, Russell G.; Forland, Brenda M.; Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong; Bernacki, Bruce E.; Hanssen, Leonard; Gonzalez, Gerardo

    2018-01-01

    Infrared integrating sphere measurements of solid samples are important in providing reference data for contact, standoff and remote sensing applications. At the Pacific Northwest National Laboratory (PNNL) we have developed protocols to measure both the directional-hemispherical ( and diffuse (d) reflectances of powders, liquids, and disks of powders and solid materials using a commercially available, matte gold-coated integrating sphere and Fourier transform infrared spectrometer. Detailed descriptions of the sphere alignment and its use for making these reflectance measurements are given. Diffuse reflectance values were found to be dependent on the bidirectional reflection distribution function (BRDF) of the sample and the solid angle intercepted by the sphere’s specular exclusion port. To determine how well the sphere and protocols produce quantitative reflectance data, measurements were made of three diffuse and two specular standards prepared by the National institute of Standards and Technology (NIST, USA), LabSphere Infragold and Spectralon standards, hand-loaded sulfur and talc powder samples, and water. The five NIST standards behaved as expected: the three diffuse standards had a high degree of “diffuseness,” d/ = D > 0.9, whereas the two specular standards had D ≤ 0.03. The average absolute differences between the NIST and PNNL measurements of the NIST standards for both directional-hemispherical and diffuse reflectances are on the order of 0.01 reflectance units. Other quantitative differences between the PNNL-measured and calibration (where available) or literature reflectance values for these standards and materials are given and the possible origins of discrepancies are discussed. Random uncertainties and estimates of systematic uncertainties are presented. Corrections necessary to provide better agreement between the PNNL reflectance values as measured for the NIST standards and the NIST reflectance values for these same standards are also

  17. Apparent diffusion coefficient measurements with diffusion-weighted imaging for differential diagnosis of soft-tissue tumor

    Directory of Open Access Journals (Sweden)

    Yu Zou

    2016-01-01

    Conclusion: Our results provide strong evidence that patients diagnosed with malignant soft-tissue tumors have low ADC values of DWI compared to those with benign soft-tissue tumors. Therefore, ADC measurements with DWI may be reliable in differential diagnosis of soft-tissue tumors.

  18. APPLICATION Of MODEL PSP MANUAL AND SUPPORTED BY TOOL MARRIES IN A STUDY OF CASE OF BRAZILIAN PLANT OF SOFTWARE

    Directory of Open Access Journals (Sweden)

    Denis Ávila Montini

    2006-06-01

    Full Text Available In a context of continuous improvement of quality in software development’s projects, the PSP experimental process was applied to discipline some of the processes suggested by CMMI level 2 with two different strategies. The first one consists of observing the behavior of a software factory on collecting the necessary data to assist the PSP model manually, and in the second one the collecting happened with the help of a CASE tool. The results show the impacts in the performance and in the quality patterns that the two strategies provided with their advantages and their vulnerabilities. In both cases the fulfillment of the stated periods was obtained from the moment where the specification and the course of the activities were controlled by the two PSP’ strategies suggested. Key words: CMMI, PSP, CASE, Factory, Improvement of processes.

  19. Isolation, purification and spectrometric analysis of PSP toxins from moraxella sp., a bacterium associated with a toxic dinoflagellate

    Energy Technology Data Exchange (ETDEWEB)

    Boyce, S.D.; Doucette, G.J.

    1994-12-31

    Paralytic shellfish poisoning (PSP) is a seafood intoxication syndrome caused by the injestion of shellfish contaminated with toxins produced by algae known as dinoflagellates. The PSP toxins, saxitoxin and its derivatives, act to block voltage-dependent sodium channels and can cause paralysis and even death at higher doses. It is well documented that bacteria coexist with many harmful or toxic algal species, though the exact nature of the association in relation to toxin production is unknown. Recently, the bacterium Moraxella sp. was isolated from the PSP toxin producing dinoflagellate Alexandrium tamarense. Through HPLC analysis and saxitoxin receptor binding assays performed on crude bacterial extracts, it appears that Moraxella sp. is capable of producing saxitoxin and several of its derivatives. However, physical confirmation (e.g. mass spectrometry) of these results is still needed.

  20. Direct measurement of nanoscale lithium diffusion in solid battery materials using radioactive tracer of {sup 8}Li

    Energy Technology Data Exchange (ETDEWEB)

    Ishiyama, H.; Jeong, S.C. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Rare Isotope Science Project (RISP), Institute for Basic Science (IBS), Daejeon 305-811 (Korea, Republic of); Watanabe, Y.X.; Hirayama, Y. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Imai, N. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Center for Nuclear Studies (CNS), Tokyo University, Wako, Saitama 351-0198 (Japan); Jung, H.S.; Miyatake, H.; Oyaizu, M. [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Osa, A.; Otokawa, Y.; Matsuda, M.; Nishio, K.; Makii, H.; Sato, T.K. [Japan Atomic Energy Agency (JAEA), Shirane 2-4, Tokai, Ibaraki 319-1195 (Japan); Kuwata, N.; Kawamura, J. [Institute of Multidisciplinary Research for Advance Materials, Tohoku University, Sendai 980-8577 (Japan); Ueno, H. [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Kim, Y.H. [Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-747 (Korea, Republic of); Kimura, S.; Mukai, M. [University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)

    2016-06-01

    We have developed an in situ and nanoscale Li diffusion measurement method in Li battery materials using an α-emitting radioactive {sup 8}Li tracer. In this method, while implanting a low-energy (8 keV) {sup 8}Li beam, the α particles emitted at a small angle (10°) relative to the sample surface were detected as a function of time. Measurement for Li diffusion coefficients in a spinel phase LiMn{sub 2}O{sub 4} (LMO) thin film has been started, which is used as an electrode in a Li ion secondary battery. An obvious Li diffusion effect in LMO was observed at the sample temperature of 623 K, and the further measurement is underway.

  1. Composition-independent mean temperature measurements in laminar diffusion flames using spectral lineshape information

    Science.gov (United States)

    Zelenak, D.; Narayanaswamy, V.

    2017-10-01

    Temperature is an important thermochemical property in combusting flows that holds the key to uncovering pollutant formation, flame extinction, and heat release. In a practical combustion environment, the local composition is typically unknown, which hinders the effectiveness of many traditional non-intrusive thermometry techniques. This study aims to offset this limitation by developing a laser-based thermometry technique that does not require prior knowledge of the local composition. Two methods for obtaining temperature are demonstrated in this work, both of which make use of the spectral line broadening of an absorbing species (krypton) seeded into the flow. In the first method, the local Doppler broadening is extracted from an excitation scan to yield the corresponding temperature, while the second method utilizes compositional scaling information of the collisional broadening and collisional shift to determine the temperature. Both methods are demonstrated by measuring the radial temperature profile of a steady laminar CH4/N2 diffusion flame with an air co-flow. The accuracy of the temperature measurements obtained using both methods are evaluated using corresponding temperature profiles determined from computational simulations.

  2. Soot particle size measurements in ethylene diffusion flames at elevated pressures

    KAUST Repository

    Steinmetz, Scott

    2016-05-07

    Soot particle size is investigated in laminar nitrogen-diluted ethylene coflow diffusion flames at 4, 8, 12 and 16 atm. Line of sight attenuation and scattering are used to measure two-dimensional soot volume fraction and particle size fields for the first time at elevated pressures. Soot volume fraction dependence on pressure is consistent with the observations of similar studies, scaling approximately with the square of pressure. Scattering intensity is analyzed through Rayleigh and Rayleigh-Debye-Gans polydisperse fractal aggregate theories to provide two estimates of particle size. An increase in overall particle sizes with pressure is found, consistent with similar one-dimensional studies. Particle diameters in the annulus of the flame increase faster with pressure than those on centerline. Contrary to previous studies, the dependence of particle size on pressure was found to taper off between 8 and 12 atm, with little observed growth beyond 12 atm. The measurements provide additional data for one of the International Sooting Flame (ISF) workshop\\'s target pressurized flames.

  3. Simultaneous temperature and multispecies measurement in a lifted hydrogen diffusion flame

    Science.gov (United States)

    Cheng, T. S.; Wehrmeyer, J. A.; Pitz, R. W.

    1992-01-01

    UV spontaneous vibrational Raman scattering and laser-induced predissociative fluorescence (LIPF) techniques are combined and applied to a lifted hydrogen jet diffusion flame. Simultaneous, temporally and spatially resolved point measurements of temperature, major species concentrations (H2, O2, N2, H2O), and absolute hydroxyl radical concentration (OH) are obtained with a 'single' excimer laser for the first time. For OH measurements, the use of LIPF makes quenching corrections unnecessary. Results demonstrate that fuel and oxidizer are in a rich, premixed, and unignited condition in the center core of the lifted flame base. In the lifted zone, combustion occurs in an intermittent annular turbulent flame brush and strong finite-rate chemistry effects result in nonequilibrium values of temperature, major species, and OH radicals. Downstream in the slow three-body recombination zone, the major species concentrations are in partial equilibrium, the OH concentrations are in superequilibrium, and the temperatures are in subequilibrium. Far downstream in the flame, equilibrium values of temperature, OH radical, and major species are found.

  4. Improved measurement of the spectral index of the diffuse radio background between 90 and 190 MHz

    Science.gov (United States)

    Mozdzen, T. J.; Bowman, J. D.; Monsalve, R. A.; Rogers, A. E. E.

    2017-02-01

    We report absolutely calibrated measurements of diffuse radio emission between 90 and 190 MHz from the Experiment to Detect the Global EoR Signature (EDGES). EDGES employs a wide beam zenith-pointing dipole antenna centred on a declination of -26.7°. We measure the sky brightness temperature as a function of frequency averaged over the EDGES beam from 211 nights of data acquired from 2015 July to 2016 March. We derive the spectral index, β, as a function of local sidereal time (LST) and find -2.60 > β > -2.62 ± 0.02 between 0 and 12 h LST. When the Galactic Centre is in the sky, the spectral index flattens, reaching β = -2.50 ± 0.02 at 17.7 h. The EDGES instrument is shown to be very stable throughout the observations with night-to-night reproducibility of σβ GSM) of de Oliveira-Costa et al. and with fits between the Guzmán et al. 45 MHz and Haslam et al. 408 MHz maps. We find good agreement at the transit of the Galactic Centre. Away from transit, the GSM tends to overpredict (GSM less negative) by 0.05 < Δβ = βGSM - βEDGES < 0.12, while the 45-408 MHz fits tend to overpredict by Δβ < 0.05.

  5. Surface charge measurements on different dielectrics in diffuse and filamentary barrier discharges

    Science.gov (United States)

    Tschiersch, R.; Nemschokmichal, S.; Bogaczyk, M.; Meichsner, J.

    2017-03-01

    Previously, we reported on the measurement of surface charges during the operation of barrier discharges (BDs) using the electro-optic Pockels effect of a bismuth silicon oxide (BSO) crystal. With the present work, the next milestone is achieved by making this powerful method accessible to various dielectrics which are typically used in BD configurations. The dynamics and spatial distribution of positive and negative surface charges were determined on optically transparent borosilicate glass, mono-crystalline alumina and magnesia, respectively, covering the BSO crystal. By variation of the nitrogen admixture to helium and the pressure between 500~\\text{mbar} and 1~\\text{bar} , both the diffuse glow-like BD and the self-stabilized discharge filaments were operated inside of a gas gap of 3~\\text{mm} . The characteristics of the discharge and, especially, the influence of the different dielectrics on its development were studied by surface charge diagnostics, electrical measurements and ICCD camera imaging. Regarding the glow-like BD, the breakdown voltage changes significantly by variation of the cathodic dielectric, due to the different effective secondary electron emission (SEE) coefficients. These material-specific SEE yields were estimated using Townsend’s criterion in combination with analytical calculations of the effective ionization coefficient in helium with air impurities. Moreover, the importance of the surface charge memory effect for the self-stabilization of discharge filaments was quantified by the recalculated spatio-temporal behavior of the gap voltage.

  6. Changes in scalp and cortical blood flow during hyperventilation measured with diffusing-wave spectroscopy

    Science.gov (United States)

    Li, Jun; Ninck, Markus; Gisler, Thomas

    2009-07-01

    Changes in scalp and cortical blood flow induced by voluntary hyperventilation are investigated by near-infrared diffusing-wave spectroscopy. The temporal intensity autocorrelation function g(2) (τ) of multiply scattered light is recorded from the forehead of subjects during hyperventilation. Blood flow within the sampled tissue volume is estimated by the mean decay rate of g(2) (τ) . Data measured from six subjects show that the pattern of the hemodynamic response during 50 s hyperventilation is rather complicated: within the first 10 s, in three subjects an initial increase in blood flow is observed; from 10 s to 20 s, the mean blood flow is smaller than its baseline value for all six subjects; for the duration from 20 s to 30 s, the blood flow increases again. However, after 30 s the change is not consistent across subjects. Further study on one of these subjects by using two receivers probing the blood flow in the cortex and in the superficial layers simultaneously, reveals that during hyperventilation, the direction of change in blood flow within the scalp is opposite to the one in the brain. This helps to understand the complicated hemodynamic response observed in our measurements.

  7. Investigation of Unsteady Pressure-Sensitive Paint (uPSP) and a Dynamic Loads Balance to Predict Launch Vehicle Buffet Environments

    Science.gov (United States)

    Schuster, David M.; Panda, Jayanta; Ross, James C.; Roozeboom, Nettie H.; Burnside, Nathan J.; Ngo, Christina L.; Kumagai, Hiro; Sellers, Marvin; Powell, Jessica M.; Sekula, Martin K.; hide

    2016-01-01

    This NESC assessment examined the accuracy of estimating buffet loads on in-line launch vehicles without booster attachments using sparse unsteady pressure measurements. The buffet loads computed using sparse sensor data were compared with estimates derived using measurements with much higher spatial resolution. The current method for estimating launch vehicle buffet loads is through wind tunnel testing of models with approximately 400 unsteady pressure transducers. Even with this relatively large number of sensors, the coverage can be insufficient to provide reliable integrated unsteady loads on vehicles. In general, sparse sensor spacing requires the use of coherence-length-based corrections in the azimuthal and axial directions to integrate the unsteady pressures and obtain reasonable estimates of the buffet loads. Coherence corrections have been used to estimate buffet loads for a variety of launch vehicles with the assumption methodology results in reasonably conservative loads. For the Space Launch System (SLS), the first estimates of buffet loads exceeded the limits of the vehicle structure, so additional tests with higher sensor density were conducted to better define the buffet loads and possibly avoid expensive modifications to the vehicle design. Without the additional tests and improvements to the coherence-length analysis methods, there would have been significant impacts to the vehicle weight, cost, and schedule. If the load estimates turn out to be too low, there is significant risk of structural failure of the vehicle. This assessment used a combination of unsteady pressure-sensitive paint (uPSP), unsteady pressure transducers, and a dynamic force and moment balance to investigate the integration schemes used with limited unsteady pressure data by comparing them with direct integration of extremely dense fluctuating pressure measurements. An outfall of the assessment was to evaluate the potential of using the emerging uPSP technique in a production

  8. Comparison of NMR and Dynamic Light Scattering for Measuring Diffusion Coefficients of Formulated Insulin: Implications for Particle Size Distribution Measurements in Drug Products.

    Science.gov (United States)

    Patil, Sharadrao M; Keire, David A; Chen, Kang

    2017-11-01

    Particle size distribution, a measurable physicochemical quantity, is a critical quality attribute of drug products that needs to be controlled in drug manufacturing. The non-invasive methods of dynamic light scattering (DLS) and Diffusion Ordered SpectroscopY (DOSY) NMR can be used to measure diffusion coefficient and derive the corresponding hydrodynamic radius. However, little is known about their use and sensitivity as analytical tools for particle size measurement of formulated protein therapeutics. Here, DLS and DOSY-NMR methods are shown to be orthogonal and yield identical diffusion coefficient results for a homogenous monomeric protein standard, ribonuclease A. However, different diffusion coefficients were observed for five insulin drug products measured using the two methods. DOSY-NMR yielded an averaged diffusion coefficient among fast exchanging insulin oligomers, ranging between dimer and hexamer in size. By contrast, DLS showed several distinct species, including dimer, hexamer, dodecamer and other aggregates. The heterogeneity or polydisperse nature of insulin oligomers in formulation caused DOSY-NMR and DLS results to differ from each other. DLS measurements provided more quality attributes and higher sensitivity to larger aggregates than DOSY-NMR. Nevertheless, each method was sensitive to a different range of particle sizes and complemented each other. The application of both methods increases the assurance of complex drug quality in this similarity comparison.

  9. Fine-scale measurements of diffusivity in a microbial mat with NMR imaging

    NARCIS (Netherlands)

    Wieland, A.; Dusschoten, van D.; Damgaard, L.R.; Beer, de D.; Kuhl, M.; As, van H.

    2001-01-01

    Noninvasive 1H-nuclear magnetic resonance (NMR) imaging was used to investigate the diffusive properties of microbial mats in two dimensions. Pulsed field gradient NMR was used to acquire images of the H2O diffusion coefficient, Ds and multiecho imaging NMR was used to obtain images of the water

  10. Measuring diffusion-relaxation correlation maps using non-uniform field gradients of single-sided NMR devices.

    Science.gov (United States)

    Nogueira d'Eurydice, Marcel; Galvosas, Petrik

    2014-11-01

    Single-sided NMR systems are becoming a relevant tool in industry and laboratory environments due to their low cost, low maintenance and capacity to evaluate quantity and quality of hydrogen based materials. The performance of such devices has improved significantly over the last decade, providing increased field homogeneity, field strength and even controlled static field gradients. For a class of these devices, the configuration of the permanent magnets provides a linear variation of the magnetic field and can be used in diffusion measurements. However, magnet design depends directly on its application and, according to the purpose, the field homogeneity may significantly be compromised. This may prevent the determination of diffusion properties of fluids based on the natural inhomogeneity of the field using known techniques. This work introduces a new approach that extends the applicability of diffusion-editing CPMG experiments to NMR devices with highly inhomogeneous magnetic fields, which do not vary linearly in space. Herein, we propose a method to determine a custom diffusion kernel based on the gradient distribution, which can be seen as a signature of each NMR device. This new diffusion kernel is then utilised in the 2D inverse Laplace transform (2D ILT) in order to determine diffusion-relaxation correlation maps of homogeneous multi-phasic fluids. The experiments were performed using NMR MObile Lateral Explore (MOLE), which is a single-sided NMR device designed to maximise the volume at the sweet spot with enhanced depth penetration. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. A novel full-field experimental method to measure the local compressibility of gas diffusion media

    Science.gov (United States)

    Lai, Yeh-Hung; Li, Yongqiang; Rock, Jeffrey A.

    The gas diffusion medium (GDM) in a proton exchange membrane (PEM) fuel cell needs to simultaneously satisfy the requirements of transporting reactant gases, removing product water, conducting electrons and heat, and providing mechanical support to the membrane electrode assembly (MEA). Concerning the localized over-compression which may force carbon fibers and other conductive debris into the membrane to cause fuel cell failure by electronically shorting through the membrane, we have developed a novel full-field experimental method to measure the local thickness and compressibility of GDM. Applying a uniform air pressure upon a thin polyimide film bonded on the top surface of the GDM with support from the bottom by a flat metal substrate and measuring the thickness change using the 3-D digital image correlation technique with an out-of-plane displacement resolution less than 0.5 μm, we have determined the local thickness and compressive stress/strain behavior in the GDM. Using the local thickness and compressibility data over an area of 11.2 mm × 11.2 mm, we numerically construct the nominal compressive response of a commercial Toray™ TGP-H-060 based GDM subjected to compression by flat platens. Good agreement in the nominal stress/strain curves from the numerical construction and direct experimental flat-platen measurement confirms the validity of the methodology proposed in this article. The result shows that a nominal pressure of 1.4 MPa compressed between two flat platens can introduce localized compressive stress concentration of more than 3 MPa in up to 1% of the total area at various locations from several hundred micrometers to 1 mm in diameter. We believe that this full-field experimental method can be useful in GDM material and process development to reduce the local hard spots and help to mitigate the membrane shorting failure in PEM fuel cells.

  12. The Morphology of Chromium and LIF Measurement of Atomic Arsenic in Laminar Diffusion Flames

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Young Bin [Department of Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of)

    1997-06-26

    The morphology and size distribution of chromium oxides and the concentration measurement of atomic arsenic have been studied in laminar diffusion flames. Nitrogen was added to vary flame temperatures in hydrogen flames. Ethene flames were used in order to investigate the potential for interaction between the soot aerosol that is formed in these flames and the chromium aerosol. Two sources of chromium compounds were introduced:chromium nitrate and chromium hexacarbonyl. A detailed investigation of the morphology was carried out by scanning electron microscopy(SEM). The amounts of Cr(VI) and total Cr were determined by a spectrophotometric method and by X-ray fluorescence spectrometry, respectively. Also, LIF was used for the measurement of atomic arsenic, which was excited at 197.2 nm and was detected at 249.6 nm. Results showed that the morphology of the particles varied with the flame temperature and with the chromium source. The particles were characterized by porous structures, cenospheres and agglomerated dense particles when chromium nitrate solution was added to the flames. At low to moderate temperature, porous sintered cenospheric structures were formed, in some cases with a blow hole. At higher temperatures, an agglomerated cluster which was composed Cr(VI) from the undiluted H{sub 2} flame was more than 10 times larger than in the 50%H{sub 2}/50%N{sub 2} flame on a mass basis. Single point LIF measurement of atomic arsenic indicated that arsenic exist only in the low temperature, fuel rich region. (author). 14 refs., 1 tab., 7 figs.

  13. Instrumentation considerations for measurement of early arriving photons in diffuse optical tomography

    Science.gov (United States)

    Valim, Niksa; Niedre, Mark

    2012-03-01

    Time-resolved measurement of early-arriving photons has been shown by a number of groups to effectively reduce photon scatter and improve resolution in diffuse optical tomography (DOT) and fluorescence mediated tomography (FMT). Recently, we experimentally showed that measurement of early-arriving photons resulted in the reduction of the instrument photon density sensitivity function (PDSF) width by a factor of 2 to 2.5 over a wide range of relevant small-animal imaging conditions using a picosecond pulsed laser and time-resolved photon counting combination. However, we also showed that this experimental improvement was less than predicted from time-resolved Monte Carlo simulations. Specifically, a reduction by a factor of 4 or better was predicted, but this could not be achieved with our system. To better understand this, in this work we have experimentally tested the effect of a series instrumentation (hardware) parameters on the experimentally measured time-dependant PDSFs including, i) source and detector geometry, ii) detector sensitivity, iii) laser illumination intensity, and iv) instrument temporal impulse response function. Our ongoing research indicates that all of these parameters affected the relative PDSF width by as much as 10-25%, particularly at early time points. The results of this work are significant because they show in a number of cases that significant disagreement between experimental PDSFs and theoretical models exist as a result of minor changes in experimental configuration. We also anticipate that these results will be useful in the design of future time-resolved DOT and DFT imaging systems.

  14. Diffusion-weighted MR imaging of the normal pancreas: reproducibility and variations of apparent diffusion coefficient measurement at 1.5- and 3.0-Tesla.

    Science.gov (United States)

    Barral, M; Soyer, P; Ben Hassen, W; Gayat, E; Aout, M; Chiaradia, M; Rahmouni, A; Luciani, A

    2013-04-01

    To evaluate reproducibility and variations in apparent diffusion coefficient (ADC) measurement in normal pancreatic parenchyma at 1.5- and 3.0-Tesla and determine if differences may exist between the four pancreatic segments. Diffusion-weighted MR imaging of the pancreas was performed at 1.5-Tesla in 20 patients and at 3.0-Tesla in other 20 patients strictly matched for gender and age using the same b values (0, 400 and 800s/mm(2)). Two independent observers placed regions of interest within the four pancreatic segments to measure ADC at both fields. Intra- and inter-observer agreement in ADC measurement was assessed using Bland-Altman analysis and comparison between ADC values obtained at both fields using non-parametrical tests. There were no significant differences in ADC between repeated measurements and between ADC obtained at 1.5-Tesla and those at 3.0-Tesla. The 95% limits of intra-observer agreement between ADC were 2.3%-22.7% at 1.5-Tesla and 1%-24.2% at 3.0-Tesla and those for inter-observer agreement between 1.9%-14% at 1.5-Tesla and 8%-25% at 3.0-Tesla. ADC values were similar in all pancreatic segments at 3.0-T whereas the tail had lower ADC at 1.5-Tesla. ADC measurement conveys high degrees of intra- and inter-observer reproducibility. ADC have homogeneous distribution among the four pancreatic segments at 3.0-Tesla. Copyright © 2012 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  15. Longitudinal, transcranial measurement of functional activation in the rat brain by diffuse correlation spectroscopy.

    Science.gov (United States)

    Blanco, Igor; Zirak, Peyman; Dragojević, Tanja; Castellvi, Clara; Durduran, Turgut; Justicia, Carles

    2017-10-01

    Neural activity is an important biomarker for the presence of neurodegenerative diseases, cerebrovascular alterations, and brain trauma; furthermore, it is a surrogate marker for treatment effects. These pathologies may occur and evolve in a long time-period, thus, noninvasive, transcutaneous techniques are necessary to allow a longitudinal follow-up. In the present work, we have customized noninvasive, transcutaneous, diffuse correlation spectroscopy (DCS) to localize changes in cerebral blood flow (CBF) induced by neural activity. We were able to detect changes in CBF in the somatosensory cortex by using a model of electrical forepaw stimulation in rats. The suitability of DCS measurements for longitudinal monitoring was demonstrated by performing multiple sessions with the same animals at different ages (from 6 to 18 months). In addition, functional DCS has been cross-validated by comparison with functional magnetic resonance imaging (fMRI) in the same animals in a subset of the time-points. The overall results obtained with transcutaneous DCS demonstrates that it can be utilized in longitudinal studies safely and reproducibly to locate changes in CBF induced by neural activity in the small animal brain.

  16. Measurement of the diffusion coefficients of fluorescence beads and quantum dots by using fluorescence correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yesul; Lee, Jaeran; Lee, Yumi; Kim, Sokwon [University of Ulsan, Ulsan (Korea, Republic of)

    2011-11-15

    FCS (fluorescence correlation spectroscopy) is a technique used to determine the dynamic characteristics of particles in solution and became common in the field of biophysics with the development of the confocal microscope, the high-speed photo-detector, and real-time data acquisition systems. In this study, the FCS system was composed of a commercial fluorescence microscope, a He-Ne laser (632.8 nm), a data acquisition board, and a software correlator written with LabVIEW. Autocorrelation functions were obtained using the measured fluorescence fluctuations of fluorescent beads and Q-dots (quantum dots) coated with carboxylate in distilled water. The diffusion coefficients of the beads and the Q-dots in distilled water and PBS (phosphate buffered saline) solution were obtained using the viscosity of water and the bead size. Also, using the bead size, we calculated the viscosity of the PBS solution, and we compared the Q-dots in water and in the PBS solution. The result showed that the viscosity of the PBS solution was 2.5 times greater than that of water, and that the sizes of Q-dots in water and PBS solution were one-third and one-sixth smaller than the known values, respectively, due to the pH variation in the solutions.

  17. Measurements of residual strains in ceramic-elastomer composites with diffuse scattering of polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Zajac, Wojciech [H. Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow (Poland)], E-mail: Wojciech.Zajac@ifj.edu.pl; Boczkowska, Anna; Babski, Kamil; Kurzydlowski, Krzysztof J. [Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02-507 Warsaw (Poland); Deen, Pascale P. [Institute Laue-Langevin, 6 rue Jules Horowitz, 38000 Grenoble (France)

    2008-12-15

    An experiment of diffuse scattering (also referred to as wide-angle neutron scattering) of polarized neutrons with polarization analysis was performed in order to detect residual strains in ceramic-elastomer composites of porous SiO{sub 2} and poly(urea-urethane) elastomers. Two ceramics, with pore sizes of 20 and 70 {mu}m, and two elastomers, with hard/soft segments molar ratios of H/S = 0.25 and 1.5, were selected for composite fabrication. The use of polarization analysis made it possible to detect and study very weak coherent scattering peaks from the elastomer synthesized inside SiO{sub 2} ceramics. Residual strains were detected and measured based on interatomic distances in the SiO{sub 2}+ H/S = 1.5 composite but not in the SiO{sub 2}+ H/S = 0.25. The reason is sought in soft domains being ordered in the H/S = 0.25 elastomer as opposed to the H/S = 1.5 one.

  18. In vivo measurement of apparent diffusion coefficients of hyperpolarized 13C‐labeled metabolites

    DEFF Research Database (Denmark)

    Søgaard, Lise Vejby; Schilling, Franz; Janich, Martin A.

    2014-01-01

    The combination of hyperpolarized MRS with diffusion weighting (dw) allows for determination of the apparent diffusion coefficient (ADC), which is indicative of the intra‐ or extracellular localization of the metabolite. Here, a slice‐selective pulsed‐gradient spin echo sequence was implemented...... of two lower than the ADC of [1‐13C]pyruvate (1.1–1.5 µm2/ms). This indicates a more restricted diffusion space for the former two metabolites consistent with lactate and alanine being intracellular. The higher ADC for pyruvate (similar to the proton ADC) reflected that the injected substance...

  19. Comparison of diffusion tractography and tract-tracing measures of connectivity strength in rhesus macaque connectome.

    Science.gov (United States)

    van den Heuvel, Martijn P; de Reus, Marcel A; Feldman Barrett, Lisa; Scholtens, Lianne H; Coopmans, Fraukje M T; Schmidt, Ruben; Preuss, Todd M; Rilling, James K; Li, Longchuan

    2015-08-01

    With the mapping of macroscale connectomes by means of in vivo diffusion-weighted MR Imaging (DWI) rapidly gaining in popularity, one of the necessary steps is the examination of metrics of connectivity strength derived from these reconstructions. In the field of human macroconnectomics the number of reconstructed fiber streamlines (NOS) is more and more used as a metric of cortico-cortical interareal connectivity strength, but the link between DWI NOS and in vivo animal tract-tracing measurements of anatomical connectivity strength remains poorly understood. In this technical report, we communicate on a comparison between DWI derived metrics and tract-tracing metrics of projection strength. Tract-tracing information on projection strength of interareal pathways was extracted from two commonly used macaque connectome datasets, including (1) the CoCoMac database of collated tract-tracing experiments of the macaque brain and (2) the high-resolution tract-tracing dataset of Markov and Kennedy and coworkers. NOS and density of reconstructed fiber pathways derived from DWI data acquired across 10 rhesus macaques was found to positively correlate to tract-tracing based measurements of connectivity strength across both the CoCoMac and Markov dataset (both P strength of white matter pathways. Our findings provide confidence of in vivo DWI connectome reconstructions to represent fairly realistic estimates of the wiring strength of white matter projections. Our cross-modal comparison supports the notion of in vivo DWI to be a valid methodology for robust description and interpretation of brain wiring. © 2015 Wiley Periodicals, Inc.

  20. Schizophrenia symptomatic associations with diffusion tensor imaging measured fractional anisotropy of brain: a meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xu [Chongqing Medical University, Department of Medical Imaging, Second Affiliated Hospital, Chongqing (China); Fifth People' s Hospital of Chongqing, Department of Medical Imaging, Chongqing (China); Cao, Ding [Chongqing Medical University, Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing (China); Liang, Xiumei [Fifth People' s Hospital of Chongqing, Department of Medical Imaging, Chongqing (China); Zhao, Jiannong [Chongqing Medical University, Department of Medical Imaging, Second Affiliated Hospital, Chongqing (China)

    2017-07-15

    Several studies have examined the relationships between diffusion tensor imaging (DTI)-measured fractional anisotropy (FA) and the symptoms of schizophrenia, but results vary across the studies. The aim of this study was to carry out a meta-analysis of correlation coefficients reported by relevant studies to evaluate the correlative relationships between FA of various parts of the brain and schizophrenia symptomatic assessments. Literature was searched in several electronic databases, and study selection was based on precised eligibility criteria. Correlation coefficients between FA of a part of the brain and schizophrenia symptom were first converted into Fisher's z-scores for meta-analyses, and then overall effect sizes were back transformed to correlation coefficients. Thirty-three studies (1121 schizophrenia patients; age 32.66 years [95% confidence interval (CI) 30.19, 35.13]; 65.95 % [57.63, 74.28] males) were included in this meta-analysis. Age was inversely associated with brain FA (z-scores [95% CI] -0.23 [-0.14, -0.32]; p %<0.00001). Brain FA of various areas was inversely associated with negative symptoms of schizophrenia (z-score -0.30 [-0.23, -0.36]; p %<0.00001) but was positively associated with positive symptoms of schizophrenia (z-score 0.16 [0.04, 0.27]; p = 0.007) and general psychopathology of schizophrenia (z-score 0.26 [0.15, 0.37]; p = 0.00001). Although, DTI-measured brain FA is found to be inversely associated with negative symptoms and positively associated with positive symptoms and general psychopathology of schizophrenia, the effect sizes of these correlations are low and may not be clinically significant. Moreover, brain FA was also negatively associated with age of patients. (orig.)

  1. Schizophrenia symptomatic associations with diffusion tensor imaging measured fractional anisotropy of brain: a meta-analysis.

    Science.gov (United States)

    Yang, Xu; Cao, Ding; Liang, Xiumei; Zhao, Jiannong

    2017-07-01

    Several studies have examined the relationships between diffusion tensor imaging (DTI)-measured fractional anisotropy (FA) and the symptoms of schizophrenia, but results vary across the studies. The aim of this study was to carry out a meta-analysis of correlation coefficients reported by relevant studies to evaluate the correlative relationships between FA of various parts of the brain and schizophrenia symptomatic assessments. Literature was searched in several electronic databases, and study selection was based on précised eligibility criteria. Correlation coefficients between FA of a part of the brain and schizophrenia symptom were first converted into Fisher's z-scores for meta-analyses, and then overall effect sizes were back transformed to correlation coefficients. Thirty-three studies (1121 schizophrenia patients; age 32.66 years [95% confidence interval (CI) 30.19, 35.13]; 65.95 % [57.63, 74.28] males) were included in this meta-analysis. Age was inversely associated with brain FA (z-scores [95% CI] -0.23 [-0.14, -0.32]; p ˂ 0.00001). Brain FA of various areas was inversely associated with negative symptoms of schizophrenia (z-score -0.30 [-0.23, -0.36]; p ˂ 0.00001) but was positively associated with positive symptoms of schizophrenia (z-score 0.16 [0.04, 0.27]; p = 0.007) and general psychopathology of schizophrenia (z-score 0.26 [0.15, 0.37]; p = 0.00001). Although, DTI-measured brain FA is found to be inversely associated with negative symptoms and positively associated with positive symptoms and general psychopathology of schizophrenia, the effect sizes of these correlations are low and may not be clinically significant. Moreover, brain FA was also negatively associated with age of patients.

  2. Evaluation and comparison of diffusion MR methods for measuring apparent transcytolemmal water exchange rate constant

    Science.gov (United States)

    Tian, Xin; Li, Hua; Jiang, Xiaoyu; Xie, Jingping; Gore, John C.; Xu, Junzhong

    2017-02-01

    Two diffusion-based approaches, CG (constant gradient) and FEXI (filtered exchange imaging) methods, have been previously proposed for measuring transcytolemmal water exchange rate constant kin, but their accuracy and feasibility have not been comprehensively evaluated and compared. In this work, both computer simulations and cell experiments in vitro were performed to evaluate these two methods. Simulations were done with different cell diameters (5, 10, 20 μm), a broad range of kin values (0.02-30 s-1) and different SNR's, and simulated kin's were directly compared with the ground truth values. Human leukemia K562 cells were cultured and treated with saponin to selectively change cell transmembrane permeability. The agreement between measured kin's of both methods was also evaluated. The results suggest that, without noise, the CG method provides reasonably accurate estimation of kin especially when it is smaller than 10 s-1, which is in the typical physiological range of many biological tissues. However, although the FEXI method overestimates kin even with corrections for the effects of extracellular water fraction, it provides reasonable estimates with practical SNR's and more importantly, the fitted apparent exchange rate AXR showed approximately linear dependence on the ground truth kin. In conclusion, either CG or FEXI method provides a sensitive means to characterize the variations in transcytolemmal water exchange rate constant kin, although the accuracy and specificity is usually compromised. The non-imaging CG method provides more accurate estimation of kin, but limited to large volume-of-interest. Although the accuracy of FEXI is compromised with extracellular volume fraction, it is capable of spatially mapping kin in practice.

  3. Diffusion weighted imaging of the normal breast: reproducibility of apparent diffusion coefficient measurements and variation with menstrual cycle and menopausal status

    Energy Technology Data Exchange (ETDEWEB)

    O' Flynn, Elizabeth A.M.; Morgan, Veronica A.; Giles, Sharon L. [Cancer Research UK and ESPSRC Cancer Imaging Centre, Clinical Magnetic Resonance Group, Surrey (United Kingdom); deSouza, Nandita M. [Royal Marsden NHS Foundation Trust, Clinical Magnetic Resonance Group, Institute of Cancer Research, Surrey (United Kingdom)

    2012-07-15

    To establish the reproducibility of apparent diffusion coefficient (ADC) measurements in normal fibroglandular breast tissue and to assess variation in ADC values with phase of the menstrual cycle and menopausal status. Thirty-one volunteers (13 premenopausal, 18 postmenopausal) underwent magnetic resonance twice (interval 11-22 days) using diffusion-weighted MRI. ADC{sub total} and a perfusion-insensitive ADC{sub high} (omitting b = 0) were calculated. Reproducibility and inter-observer variability of mean ADC values were assessed. The difference in mean ADC values between the two phases of the menstrual cycle and the postmenopausal breast were evaluated. ADC{sub total} and ADC{sub high} showed good reproducibility (r% = 17.6, 22.4). ADC{sub high} showed very good inter-observer agreement (kappa = 0.83). The intraclass correlation coefficients (ICC) were 0.93 and 0.91. Mean ADC values were significantly lower in the postmenopausal breast (ADC{sub total} 1.46 {+-} 0.3 x 10{sup -3} mm{sup 2}/s, ADC{sub high} 1.33 {+-} 0.3 x 10{sup -3} mm{sup 2}/s) compared with the premenopausal breast (ADC{sub total} 1.84 {+-} 0.26 x 10{sup -3} mm{sup 2}/s, ADC{sub high} 1.77 {+-} 0.26 x 10{sup -3} mm{sup 2}/s; both P < 0.001). No significant difference was seen in ADC values in relation to menstrual cycle (ADC{sub total} P = 0.2, ADC{sub high} P = 0.24) or between postmenopausal women taking or not taking oestrogen supplements (ADC{sub total} P = 0.6, ADC{sub high} P = 0.46). ADC values in fibroglandular breast tissue are reproducible. Lower ADC values within the postmenopausal breast may reduce diffusion-weighted contrast and have implications for accurately detecting tumours. (orig.)

  4. Full Scale Measurements and CFD Simulations of Diffuse Ceiling Inlet for Ventilation and Cooling of Densely Occupied Rooms

    DEFF Research Database (Denmark)

    Mikeska, Tomás; Fan, Jianhua

    2015-01-01

    on gypsum boards with airtight connectionswas created utilizing the full potential of diffuse layer without undesirable crack flow reported by otherauthors. The measured values were used to validate the detailed Large Eddy Simulation model of testroom created in CFD software with aim to evaluate an indoor...... comfort numerically. Results of our investigations have shown that diffuse ceiling inlet is a suitable solution for the spaceswith high density occupancy. The results have shown that transient calculations using Large Eddy Simulation models can predict well temperatures and velocity magnitude of air flow...

  5. Generalizing the flash technique in the front-face configuration to measure the thermal diffusivity of semitransparent solids

    Energy Technology Data Exchange (ETDEWEB)

    Pech-May, Nelson Wilbur [Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alameda Urquijo s/n, 48013 Bilbao (Spain); Department of Applied Physics, CINVESTAV Unidad Mérida, carretera Antigua a Progreso km6, A.P. 73 Cordemex, Mérida Yucatán 97310, México (Mexico); Mendioroz, Arantza; Salazar, Agustín, E-mail: agustin.salazar@ehu.es [Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alameda Urquijo s/n, 48013 Bilbao (Spain)

    2014-10-15

    In this work, we have extended the front-face flash method to retrieve simultaneously the thermal diffusivity and the optical absorption coefficient of semitransparent plates. A complete theoretical model that allows calculating the front surface temperature rise of the sample has been developed. It takes into consideration additional effects, such as multiple reflections of the heating light beam inside the sample, heat losses by convection and radiation, transparency of the sample to infrared wavelengths, and heating pulse duration. Measurements performed on calibrated solids, covering a wide range of absorption coefficients (from transparent to opaque) and thermal diffusivities, validate the proposed method.

  6. Advantages of the phosphatidylserine-recognizing peptide PSP1 for molecular imaging of tumor apoptosis compared with annexin V.

    Directory of Open Access Journals (Sweden)

    Soyoun Kim

    Full Text Available A number of peptide-based indicators have been identified and reported as potential apoptosis probes, offering great promise for early assessment of therapeutic efficacy in several types of cancer. Direct comparison of the newly developed probes with previously used ones would be an important step in assessing possible applications. Here, we compared the newly identified peptide-based phosphatidylserine (PS indicator PSP1 (CLSYYPSYC with annexin V, a common probe for molecular imaging of apoptotic cells, with respect to PS binding kinetics, apoptotic cell-targeting ability, and the efficacy of homing to apoptotic tumor cells in a mouse model after treatment with the anticancer agent camptothecin. Our results indicate that PSP1 efficiently targeted apoptotic cells and generated apoptosis/tumor-specific signals after cancer treatment in the animal model, whereas a similar dose of annexin V showed weak signals. The formation of a stable complex of PSP1 with PS might be one reason for the efficient in vivo targeting. We suggest that PSP1 has potential advantages for in vivo apoptotic cell imaging and could serve as a platform for the development of de novo peptide-based probes for apoptosis.

  7. Measurement and Interpretation of Diffuse Scattering in X-Ray Diffraction for Macromolecular Crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Michael E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-16

    X-ray diffraction from macromolecular crystals includes both sharply peaked Bragg reflections and diffuse intensity between the peaks. The information in Bragg scattering reflects the mean electron density in the unit cells of the crystal. The diffuse scattering arises from correlations in the variations of electron density that may occur from one unit cell to another, and therefore contains information about collective motions in proteins.

  8. Simultaneous measurement of anisotropic solute diffusivity and binding reaction rates in biological tissues by FRAP.

    Science.gov (United States)

    Travascio, Francesco; Gu, Wei Yong

    2011-01-01

    Several solutes (e.g., growth factors, cationic solutes, etc.) can reversibly bind to the extracellular matrix (ECM) of biological tissues. Binding interactions have significant implications on transport of such solutes through the ECM. In order to fully delineate transport phenomena in biological tissues, knowledge of binding kinetics is crucial. In this study, a new method for the simultaneous determination of solute anisotropic diffusivity and binding reaction rates was presented. The new technique was solely based on Fourier analysis of fluorescence recovery after photobleaching (FRAP) images. Computer-simulated FRAP tests were used to assess the sensitivity and the robustness of the method to experimental parameters, such as anisotropic solute diffusivity and rates of binding reaction. The new method was applied to the determination of diffusivity and binding rates of 5-dodecanoylaminofluorescein (DAF) in bovine coccygeal annulus fibrosus (AF). Our findings indicate that DAF reversibly binds to the ECM of AF. In addition, it was found that DAF diffusion in AF is anisotropic. The results were in agreement with those reported in previous studies. This study provides a new tool for the simultaneous determination of solute anisotropic diffusion tensor and rates of binding reaction that can be used to investigate diffusive-reactive transport in biological tissues and tissue engineered constructs.

  9. Diffusion tensor imaging measures of white matter compared to myelin basic protein immunofluorescence in tissue cleared intact brains

    Directory of Open Access Journals (Sweden)

    Eric H. Chang

    2017-02-01

    Full Text Available We provide datasets from combined ex vivo diffusion tensor imaging (DTI and Clear Lipid-exchanged, Anatomically Rigid, Imaging/immunostaining compatible, Tissue hYdrogel (CLARITY performed on intact mouse brains. DTI-derived measures of fractional anisotropy (FA, radial diffusivity (RD, and axial diffusivity (AD were compared to antibody-based labeling of myelin basic protein (MBP, as measured by fluorescence microscopy. We used a customized CLARITY hydrogel solution to facilitate whole brain tissue clearing and subsequent immunolabeling. We describe how CLARITY was made compatible with magnetic resonance imaging with the intention of facilitating future multimodal imaging studies that may combine noninvasive imaging with 3D immunohistochemistry. These data and methods are related to the accompanying research article entitled, ‘The role of myelination in measures of white matter integrity: Combination of diffusion tensor imaging and two-photon microscopy of CLARITY intact brains’ (E.H. Chang, M. Argyelan, M. Aggarwal, T-S. Chandon, K.H. Karlsgodt, S. Mori, A.K. Malhotra, 2016 [1].

  10. Electrokinetics of diffuse soft interfaces. IV. Analysis of streaming current measurements at thermoresponsive thin films.

    Science.gov (United States)

    Duval, Jérôme F L; Zimmermann, Ralf; Cordeiro, Ana L; Rein, Nelly; Werner, Carsten

    2009-09-15

    Streaming current measurements were performed on poly(N-isopropylacrylamide)-co-N-(1-phenylethyl) acrylamide [P(NIPAAm-co-PEAAm)] thermoresponsive thin films above and below the transition temperature of the polymer (i.e., at 22 and 4 degrees C, respectively). Electrokinetic measurements (ionic strength 0.01-10 mM KCl, pH 2.5-9.5 in 1 mM KCl) revealed that the charging of the polymer/aqueous solution interface is determined by unsymmetrical adsorption of hydroxide and hydronium ions onto the Teflon AF substrate that supports the hydrogel film. The magnitude of the streaming current significantly decreased with decreasing temperature, that is, when the hydrogel was swelling. The pH- and ionic strength-dependent data for unswollen and swollen films were interpreted on the basis of the here-reported general theory for the electrokinetics of diffuse soft gel layers. The formalism based on the Debye-Brinkman equation for hydrodynamics and the nonlinear Poisson-Boltzmann equation for electrostatics extends previous theoretical studies by considering the most general situation of a charged gel layer supported by a charged rigid surface. Full analytical expression is provided for the streaming current in the limit of homogeneous distribution of segments under low potential conditions. Numerical analysis of the governing transport and electrostatic equations allows for the computation of streaming current for cases where analytical developments are not possible. The theory successfully reproduces the electrokinetic data for the P(NIPAAm-co-PEAAm) copolymer film at 22 and 4 degrees C over the whole range of pH and ionic strength examined. It is found that the 3-fold increase of the hydrogel film thickness with decreasing temperature from 22 to 4 degrees C (i.e., from 23 to 70 nm as measured by ellipsometry), is in line with homogeneous swelling and an increase of the hydrodynamic penetration length (1/lambdao) by a factor of approximately 1.6. Additionally, the hydrodynamic

  11. Safety assessment of near infrared light emitting diodes for diffuse optical measurements

    Directory of Open Access Journals (Sweden)

    Onaral Banu

    2004-03-01

    Full Text Available Abstract Background Near infrared (NIR light has been used widely to monitor important hemodynamic parameters in tissue non-invasively. Pulse oximetry, near infrared spectroscopy, and diffuse optical tomography are examples of such NIR light-based applications. These and other similar applications employ either lasers or light emitting diodes (LED as the source of the NIR light. Although the hazards of laser sources have been addressed in regulations, the risk of LED sources in such applications is still unknown. Methods Temperature increase of the human skin caused by near infrared LED has been measured by means of in-vivo and in-vitro experiments. Effects of the conducted and radiated heat in the temperature increase have been analyzed separately. Results Elevations in skin temperature up to 10°C have been observed. The effect of radiated heat due to NIR absorption is low – less than 0.5°C – since emitted light power is comparable to the NIR part of sunlight. The conducted heat due to semiconductor junction of the LED can cause temperature increases up to 9°C. It has been shown that adjusting operational parameters by amplitude modulating or time multiplexing the LED decreases the temperature increase of the skin significantly. Conclusion In this study, we demonstrate that the major risk source of the LED in direct contact with skin is the conducted heat of the LED semiconductor junction, which may cause serious skin burns. Adjusting operational parameters by amplitude modulating or time multiplexing the LED can keep the LED within safe temperature ranges.

  12. Recombinant BCG expressing a PspA-PdT fusion protein protects mice against pneumococcal lethal challenge in a prime-boost strategy.

    Science.gov (United States)

    Goulart, Cibelly; Rodriguez, Dunia; Kanno, Alex I; Lu, Ying-Jie; Malley, Richard; Leite, Luciana C C

    2017-03-23

    Pneumococcal proteins have been evaluated as genetically-conserved potential vaccine candidates. We have previously demonstrated that a fragment of PspA in fusion with PdT (rPspA-PdT) induced protective immune responses in mice. However, purified proteins have shown poor immunogenicity and often require the combination with strong adjuvants and booster doses. Here, we investigated the use of a Bacillus Calmette-Guérin (BCG) strain, a well-established prophylactic vaccine for tuberculosis with known adjuvant properties, for delivery of the PspA-PdT fusion protein. Immunization of mice in a prime-boost strategy, using rPspA-PdT as a boost, demonstrated that rBCG PspA-PdT/rPspA-PdT was able to induce an antibody response against both proteins, promoting an IgG1 to IgG2 antibody isotype shift. Sera from rBCG PspA-PdT/rPspA-PdT immunized mice showed antibodies able to bind to the pneumococcal surface and promoted higher complement deposition when compared with WT-BCG/rPspA-PdT or a single dose of rPspA-PdT. In addition, these antisera inhibited the cytolytic activity of Ply. Production of interleukin-6 (IL-6), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) was increased in splenocytes culture. Furthermore, a higher expression of CD69 early activation molecule was observed on splenic CD4 + T cells from mice immunized with rBCG PspA-PdT before and after the protein booster dose. Finally, immunization with rBCG PspA-PdT/rPspA-PdT protected mice against pneumococcal lethal challenge. These results support the further investigation of recombinant BCG strains to express pneumococcal proteins, which could be administered in early stages of life and lead to protective pneumococcal immunity in infants and children. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Ground Thermal Diffusivity Calculation by Direct Soil Temperature Measurement. Application to very Low Enthalpy Geothermal Energy Systems.

    Science.gov (United States)

    Andújar Márquez, José Manuel; Martínez Bohórquez, Miguel Ángel; Gómez Melgar, Sergio

    2016-02-29

    This paper presents a methodology and instrumentation system for the indirect measurement of the thermal diffusivity of a soil at a given depth from measuring its temperature at that depth. The development has been carried out considering its application to the design and sizing of very low enthalpy geothermal energy (VLEGE) systems, but it can has many other applications, for example in construction, agriculture or biology. The methodology is simple and inexpensive because it can take advantage of the prescriptive geotechnical drilling prior to the construction of a house or building, to take at the same time temperature measurements that will allow get the actual temperature and ground thermal diffusivity to the depth of interest. The methodology and developed system have been tested and used in the design of a VLEGE facility for a chalet with basement at the outskirts of Huelva (a city in the southwest of Spain). Experimental results validate the proposed approach.

  14. Measurements of beam halo diffusion and population density in the Tevatron and in the Large Hadron Collider

    CERN Document Server

    Stancari, Giulio

    Halo dynamics influences global accelerator performance: beam lifetimes, emittance growth, dynamic aperture, and collimation efficiency. Halo monitoring and control are also critical for the operation of high-power machines. For instance, in the high-luminosity upgrade of the LHC, the energy stored in the beam tails may reach several megajoules. Fast losses can result in superconducting magnet quenches, magnet damage, or even collimator deformation. The need arises to measure the beam halo and to remove it at controllable rates. In the Tevatron and in the LHC, halo population densities and diffusivities were measured with collimator scans by observing the time evolution of losses following small inward or outward collimator steps, under different experimental conditions: with single beams and in collision, and, in the case of the Tevatron, with a hollow electron lens acting on a subset of bunches. After the LHC resumes operations, it is planned to compare measured diffusivities with the known strength of tran...

  15. Ground Thermal Diffusivity Calculation by Direct Soil Temperature Measurement. Application to very Low Enthalpy Geothermal Energy Systems

    Directory of Open Access Journals (Sweden)

    José Manuel Andújar Márquez

    2016-02-01

    Full Text Available This paper presents a methodology and instrumentation system for the indirect measurement of the thermal diffusivity of a soil at a given depth from measuring its temperature at that depth. The development has been carried out considering its application to the design and sizing of very low enthalpy geothermal energy (VLEGE systems, but it can has many other applications, for example in construction, agriculture or biology. The methodology is simple and inexpensive because it can take advantage of the prescriptive geotechnical drilling prior to the construction of a house or building, to take at the same time temperature measurements that will allow get the actual temperature and ground thermal diffusivity to the depth of interest. The methodology and developed system have been tested and used in the design of a VLEGE facility for a chalet with basement at the outskirts of Huelva (a city in the southwest of Spain. Experimental results validate the proposed approach.

  16. Quantitative Measurements of CH* Concentration in Normal Gravity and Microgravity Coflow Laminar Diffusion Flames

    Science.gov (United States)

    Giassi, D.; Cao, S.; Stocker, D. P.; Takahashi, F.; Bennett, B. A.; Smooke, M. D.; Long, M. B.

    2015-01-01

    With the conclusion of the SLICE campaign aboard the ISS in 2012, a large amount of data was made available for the analysis of the effect of microgravity on laminar coflow diffusion flames. Previous work focused on the study of sooty flames in microgravity as well as the ability of numerical models to predict its formation in a simplified buoyancy-free environment. The current work shifts the investigation to soot-free flames, putting an emphasis on the chemiluminescence emission from electronically excited CH (CH*). This radical species is of significant interest in combustion studies: it has been shown that the CH* spatial distribution is indicative of the flame front position and, given the relatively simple diagnostic involved with its measurement, several works have been done trying to understand the ability of CH* chemiluminescence to predict the total and local flame heat release rate. In this work, a subset of the SLICE nitrogen-diluted methane flames has been considered, and the effect of fuel and coflow velocity on CH* concentration is discussed and compared with both normal gravity results and numerical simulations. Experimentally, the spectral characterization of the DSLR color camera used to acquire the flame images allowed the signal collected by the blue channel to be considered representative of the CH* emission centered around 431 nm. Due to the axisymmetric flame structure, an Abel deconvolution of the line-of-sight chemiluminescence was used to obtain the radial intensity profile and, thanks to an absolute light intensity calibration, a quantification of the CH* concentration was possible. Results show that, in microgravity, the maximum flame CH* concentration increases with the coflow velocity, but it is weakly dependent on the fuel velocity; normal gravity flames, if not lifted, tend to follow the same trend, albeit with different peak concentrations. Comparisons with numerical simulations display reasonably good agreement between measured and

  17. Quantitative Measurements of Electronically Excited CH Concentration in Normal Gravity and Microgravity Coflow Laminar Diffusion Flames

    Science.gov (United States)

    Giassi, D.; Cao, S.; Stocker, D. P.; Takahashi, F.; Bennett, B. A. V.; Smooke, M. D.; Long, M. B.

    2015-01-01

    With the conclusion of the SLICE campaign aboard the ISS in 2012, a large amount of data was made available for the analysis of the effect of microgravity on laminar coflow diffusion flames. Previous work focused on the study of sooty flames in microgravity as well as the ability of numerical models to predict its formation in a simplified buoyancy-free environment. The current work shifts the investigation to soot-free flames, putting an emphasis on the chemiluminescence emission from electronically excited CH (CH*). This radical species is of significant interest in combustion studies: it has been shown that the electronically excited CH spatial distribution is indicative of the flame front position and, given the relatively simple diagnostic involved with its measurement, several works have been done trying to understand the ability of electronically excited CH chemiluminescence to predict the total and local flame heat release rate. In this work, a subset of the SLICE nitrogen-diluted methane flames has been considered, and the effect of fuel and coflow velocity on electronically excited CH concentration is discussed and compared with both normal gravity results and numerical simulations. Experimentally, the spectral characterization of the DSLR color camera used to acquire the flame images allowed the signal collected by the blue channel to be considered representative of the electronically excited CH emission centered around 431 nm. Due to the axisymmetric flame structure, an Abel deconvolution of the line-of-sight chemiluminescence was used to obtain the radial intensity profile and, thanks to an absolute light intensity calibration, a quantification of the electronically excited CH concentration was possible. Results show that, in microgravity, the maximum flame electronically excited CH concentration increases with the coflow velocity, but it is weakly dependent on the fuel velocity; normal gravity flames, if not lifted, tend to follow the same trend

  18. A new gas/supercritical fluid (SCF diffusivity measurement method for CO2 saturated polymer systems using a dielectric property

    Directory of Open Access Journals (Sweden)

    S. X. Yao

    2017-08-01

    Full Text Available In this research, theoretical CO2 diffusivity coefficients in amorphous polymers were calculated from dielectric constant changes during CO2 desorption. These values showed agreement with experimental diffusivity coefficients from a gravimetric method. Three amorphous polymer films made from Polystyrene (PS, Polycarbonate (PC, and Cyclic Olefin Polymer (COP resins were saturated with supercritical CO2 at 5.5 MPa and 25 °C for 24 hours in a pressure chamber. The CO2 infused films were removed from the chamber for gas desorption experiments. The capacitance of the samples were recorded with an Inductance, Capacitance and Resistance (LCR meter. These values were used to calculate the change in dielectric constants. CO2 weight percentages measured by a scale was used to calculate experimental diffusivity and solubility coefficients. It was found that the trend of dielectric constant changes was similar to that of the CO2 weight percentage changes during gas desorption. A mathematical model was built to predict the CO2 weight percentages during desorption from the measured dielectric constants. Theoretical diffusivity coefficients from this work agree well with literature data.

  19. Characterizing acid diffusion lengths in chemically amplified resists from measurements of deprotection kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Abhijit A. [University of Houston, Department of Chemical and Biomolecular Engineering, 4800 Calhoun Road, Houston, Texas 77204, United States; Pandey, Yogendra Narayan [University of Houston, Department of Chemical and Biomolecular Engineering, 4800 Calhoun Road, Houston, Texas 77204, United States; Doxastakis, Manolis [Institute for Molecular Engineering, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States; Stein, Gila E. [University of Houston, Department of Chemical and Biomolecular Engineering, 4800 Calhoun Road, Houston, Texas 77204, United States

    2014-10-01

    The acid-catalyzed deprotection of glassy poly(4-hydroxystyrene-co-tertbutyl acrylate) films was studied with infrared absorbance spectroscopy and stochastic simulations. Experimental data were interpreted with a simple description of subdiffusive acid transport coupled to second-order acid loss. This model predicts key attributes of observed deprotection rates, such as fast reaction at short times, slow reaction at long times, and a nonlinear dependence on acid loading. Fickian diffusion is approached by increasing the post-exposure bake temperature or adding plasticizing agents to the polymer resin. These findings demonstrate that acid mobility and overall deprotection kinetics are coupled to glassy matrix dynamics. To complement the analysis of bulk kinetics, acid diffusion lengths were calculated from the anomalous transport model and compared with nanopattern line widths. The consistent scaling between experiments and simulations suggests that the anomalous diffusion model could be further developed into a predictive lithography tool.

  20. Mass diffusion coefficient measurement for vitreous humor using FEM and MRI

    Science.gov (United States)

    Rattanakijsuntorn, Komsan; Penkova, Anita; Sadha, Satwindar S.

    2018-01-01

    In early studies, the ‘contour method’ for determining the diffusion coefficient of the vitreous humor was developed. This technique relied on careful injection of an MRI contrast agent (surrogate drug) into the vitreous humor of fresh bovine eyes, and tracking the contours of the contrast agent in time. In addition, an analytical solution was developed for the theoretical contours built on point source model for the injected surrogate drug. The match between theoretical and experimental contours as a least square fit, while floating the diffusion coefficient, led to the value of the diffusion coefficient. This method had its limitation that the initial injection of the surrogate had to be spherical or ellipsoidal because of the analytical result based on the point-source model. With a new finite element model for the analysis in this study, the technique is much less restrictive and handles irregular shapes of the initial bolus. The fresh bovine eyes were used for drug diffusion study in the vitreous and three contrast agents of different molecular masses: gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA, 938 Da), non-ionic gadoteridol (Prohance, 559 Da), and bovine albumin conjugated with gadolinium (Galbumin, 74 kDa) were used as drug surrogates to visualize the diffusion process by MRI. The 3D finite element model was developed to determine the diffusion coefficients of these surrogates with the images from MRI. This method can be used for other types of bioporous media provided the concentration profile can be visualized (by methods such as MRI or fluorescence).

  1. Multitracer and filter-separated half-cell method for measuring solute diffusion in undisturbed soil

    DEFF Research Database (Denmark)

    Lægdsmand, Mette; Møldrup, Per; Schjønning, Per

    2010-01-01

    in the soil relative to water) in intact soil samples (the Multiple Tracer, Filter Separated half-cell method using a Dynamic Model for parameter estimation [MT-FS-DM]). The MT-FS-DM method consists of half-cell diffusion of two pairs of counterdiffusing anionic tracers and a parameter estimation scheme...... that allows diffusion coefficients for tracers in the two half-cells to be estimated on the basis of two concentration profiles in each sample. The parameter estimation scheme uses a fully dynamic (time-resolved) simulation model. From sensitivity and uncertainty analyses of the dynamic model, we found...

  2. Diffuse reflectance spectra measured in vivo in human tissues during Photofrin-mediated pleural photodynamic therapy: updated results

    Science.gov (United States)

    Finlay, Jarod C.; Zhu, Timothy C.; Dimofte, Andreea; Friedberg, Joseph S.; Cengel, Keith A.; Hahn, Stephen M.

    2009-02-01

    We present the results of a series of spectroscopic measurements made in vivo in patients undergoing photodynamic therapy (PDT). The patients studied here were enrolled in Phase II clinical trials of Photofrin-mediated PDT for the treatment of non-small cell lung cancer and cancers with pleural effusion. Patients were given Photofrin at dose of 2 mg per kg body weight 24 hours prior to treatment. Each patient received surgical debulking of the tumor followed by intracavity PDT at 630nm to a dose of 60 J/cm2. Dose was monitored continuously using implanted isotropic fiber-based light detectors. We measured the diffuse reflectance spectra before and after PDT in various positions within the cavity, including tumor, diaphragm, pericardium, skin, and chest wall muscle in 10 patients. The measurements were acquired using a specially designed fiber optic-based probe consisting of one fluorescence excitation fiber, one white light delivery fiber, and 9 detection fibers spaced at distances from 0.36 to 7.8 mm from the source, all of which are imaged via a spectrograph onto a CCD, allowing measurement of radially-resolved diffuse reflectance and fluorescence spectra. The absorption spectra were analyzed using an analytical model of light propagation in diffuse media based on the P3 approximation to radiative transport, assuming a known basis set of absorbers including hemoglobin in its oxygenated and deoxygenated forms and Photofrin. We find significant variation in hemodynamics and sensitizer concentration among patients and within tissues in a single patient.

  3. Comparison of diffusion tractography and tract-tracing measures of connectivity strength in rhesus macaque connectome

    NARCIS (Netherlands)

    van den Heuvel, Martijn P.; de Reus, Marcel A.; Feldman Barrett, Lisa; Scholtens, Lianne H.; Coopmans, Fraukje M T; Schmidt, Ruben; Preuss, Todd M.; Rilling, James K.; Li, Longchuan

    2015-01-01

    With the mapping of macroscale connectomes by means of in vivo diffusion-weighted MR Imaging (DWI) rapidly gaining in popularity, one of the necessary steps is the examination of metrics of connectivity strength derived from these reconstructions. In the field of human macroconnectomics the number

  4. Density profile evolution and nonequilibrium effects in partial and full spreading measurements of surface diffusion

    DEFF Research Database (Denmark)

    Nikunen, P.; Vattulainen, Ilpo Tapio; Ala-Nissila, T.

    2001-01-01

    (theta) to determine the locations of phase boundaries and find such data to be clearly time dependent during full spreading. We conclude that nonequilibrium effects seem to be an inherent feature in profile evolution studies of surface diffusion in all cases where ordering plays a prominent role. This warrants...

  5. Stability results for a reaction-diffusion system with a single measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ramoul, Hichem [Centre universitaire de Khenchela, Route de Batna, BP 1252, Liberte, 40004 Khenchela (Algeria); Gaitan, Patricia [Laboratoire d' analyse, topologie, probabilites CNRS UMR 6632, Marseille (France) and Universite Aix-Marseille II (France); Cristofol, Michel [Laboratoire d' analyse, topologie, probabilites CNRS UMR 6632, Marseille, France and Universite Aix-Marseille III (France)

    2007-06-15

    For a two by two reaction-diffusion system on a bounded domain we give a simultaneous stability result for one coefficient and for the initial conditions. The key ingredient is a global Carleman-type estimate with a single observation acting on a subdomain.

  6. Constraints on the Galactic Halo Dark Matter from Fermi-LAT Diffuse Measurements

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; hide

    2012-01-01

    We have performed an analysis of the diffuse gamma-ray emission with the Fermi Large Area Telescope (LAT) in the Milky Way halo region, searching for a signal from dark matter annihilation or decay. In the absence of a robust dark matter signal, constraints are presented. We consider both gamma rays produced directly in the dark matter annihilation/decay and produced by inverse Compton scattering of the e+/e- produced in the annihilation/decay. Conservative limits are derived requiring that the dark matter signal does not exceed the observed diffuse gamma-ray emission. A second set of more stringent limits is derived based on modeling the foreground astrophysical diffuse emission using the GALPROP code. Uncertainties in the height of the diffusive cosmic-ray halo, the distribution of the cosmic-ray sources in the Galaxy, the index of the injection cosmic-ray electron spectrum, and the column density of the interstellar gas are taken into account using a profile likelihood formalism, while the parameters governing the cosmic-ray propagation have been derived from fits to local cosmic-ray data. The resulting limits impact the range of particle masses over which dark matter thermal production in the early universe is possible, and challenge the interpretation of the PAMELA/Fermi-LAT cosmic ray anomalies as the annihilation of dark matter.

  7. Ion Permeability of Artificial Membranes Evaluated by Diffusion Potential and Electrical Resistance Measurements

    Science.gov (United States)

    Shlyonsky, Vadim

    2013-01-01

    In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and "n"-decane. The electrical resistance and potential…

  8. A novel diffusion-tensor MRI approach for skeletal muscle fascicle length measurements

    NARCIS (Netherlands)

    Oudeman, Jos; Mazzoli, Valentina; Marra, Marco A.; Nicolay, Klaas; Maas, Mario; Verdonschot, Nico; Sprengers, Andre M.; Nederveen, Aart J.; Strijkers, Gustav J.; Froeling, Martijn

    2016-01-01

    Musculoskeletal (dys-)function relies for a large part on muscle architecture which can be obtained using Diffusion-Tensor MRI (DT-MRI) and fiber tractography. However, reconstructed tracts often continue along the tendon or aponeurosis when using conventional methods, thus overestimating fascicle

  9. Diffusion abnormalities of the uncinate fasciculus in Alzheimer's disease: diffusion tensor tract-specific analysis using a new method to measure the core of the tract

    Energy Technology Data Exchange (ETDEWEB)

    Yasmin, Hasina; Nakata, Yasuhiro; Abe, Osamu; Masutani, Yoshitaka; Ohtomo, Kuni [University of Tokyo, Department of Radiology, Tokyo (Japan); Aoki, Shigeki [University of Tokyo, Department of Radiology, Tokyo (Japan); Sato, Noriko [National Center of Neurology and Psychiatry, Department of Radiology, National Center Hospital for Mental, Nervous and Muscular Disorders, Tokyo (Japan); Nemoto, Kiyotaka [Ibaraki Prefectural Tomobe Hospital, Department of Psychiatry, Ibaraki (Japan); Arima, Kunimasa; Furuta, Nobuo [National Center of Neurology and Psychiatry, Department of Psychiatry, National Center Hospital for Mental, Nervous and Muscular Disorders, Tokyo (Japan); Uno, Masatake [Yoshioka Rehabilitation Clinic, Department of Psychiatry, Tokyo (Japan); Hirai, Shigeo [Iruma Hirai Clinic, Department of Psychiatry, Saitama (Japan)

    2008-04-15

    Our aim was to determine diffusion abnormalities in the uncinate fasciculus (UF) in Alzheimer's disease (AD) by diffusion tensor tractography (DTT) using a new method for measuring the core of the tract. We studied 19 patients with AD and 19 age-matched control subjects who underwent MRI using diffusion tensor imaging (DTI). DTT of the UF was generated. The mean diffusivity (MD) and fractional anisotropy (FA) of the core of the tract were measured after voxelized tract shape processing. Student's t-test was used to compare results between patients with AD and controls. Intraobserver correlation tests were also performed. FA was significantly lower (P < 0.0001) in the UF of patients with AD than of controls. There was no significant difference in MD along the UF between the two groups. Intraobserver reliability (intraclass correlation coefficient) for the first and second measurement was r > 0.93 for measured FA and r > 0.92 for measured MD. Our results suggest that FA reflects progression of AD-related histopathological changes in the UF of the white matter and may represent a useful biological index in monitoring AD. Diffusion tensor tract-specific analysis with voxelized tract shape processing to measure the core of the tract may be a sensitive tool for evaluation of diffusion abnormalities of white matter tracts in AD. (orig.)

  10. The measuring technique developed to evaluate the thermal diffusivity of the multi-layered thin film specimens

    Directory of Open Access Journals (Sweden)

    Li Tse-Chang

    2017-01-01

    Full Text Available In the present study, the thermal diffusivities of the Al, Si and ITO films deposited on the SUS304 steel substrate are evaluated via the present technique. Before applying this technique, the temperature for the thin film of the multi-layered specimen is developed theoretically for the one- dimensional steady heat conduction in response to amplitude and frequency of the periodically oscillating temperature imposed by a peltier placed beneath the specimen's substrate. By the thermal-electrical data processing system excluding the lock-in amplifier, the temperature frequency a3 has been proved first to be independent of the electrical voltage applied to the peltier and the contact position of the thermocouples. The experimental data of phase difference for three kinds of specimen are regressed well by a straight line with a slope. Then, the thermal diffusivity of the thin film is thus determined if the slope value and the film- thickness are available. In the present arrangements for the thermocouples, two thermal diffusivity values are quite close each other and valid for every kind of specimen. This technique can provide an efficient, low-cost method for the thermal diffusivity measurements of thin films.

  11. Diffusion measures indicate fight exposure-related damage to cerebral white matter in boxers and mixed martial arts fighters.

    Science.gov (United States)

    Shin, W; Mahmoud, S Y; Sakaie, K; Banks, S J; Lowe, M J; Phillips, M; Modic, M T; Bernick, C

    2014-02-01

    Traumatic brain injury is common in fighting athletes such as boxers, given the frequency of blows to the head. Because DTI is sensitive to microstructural changes in white matter, this technique is often used to investigate white matter integrity in patients with traumatic brain injury. We hypothesized that previous fight exposure would predict DTI abnormalities in fighting athletes after controlling for individual variation. A total of 74 boxers and 81 mixed martial arts fighters were included in the analysis and scanned by use of DTI. Individual information and data on fight exposures, including number of fights and knockouts, were collected. A multiple hierarchical linear regression model was used in region-of-interest analysis to test the hypothesis that fight-related exposure could predict DTI values separately in boxers and mixed martial arts fighters. Age, weight, and years of education were controlled to ensure that these factors would not account for the hypothesized effects. We found that the number of knockouts among boxers predicted increased longitudinal diffusivity and transversal diffusivity in white matter and subcortical gray matter regions, including corpus callosum, isthmus cingulate, pericalcarine, precuneus, and amygdala, leading to increased mean diffusivity and decreased fractional anisotropy in the corresponding regions. The mixed martial arts fighters had increased transversal diffusivity in the posterior cingulate. The number of fights did not predict any DTI measures in either group. These findings suggest that the history of fight exposure in a fighter population can be used to predict microstructural brain damage.

  12. Measurement of ²²²Rn diffusion through sandy soil with solar cells photodiodes as the detector.

    Science.gov (United States)

    Shitrit, Y; Dody, A; Alfassi, Z B; Berant, Z

    2012-02-01

    An experimental system was developed to study the diffusion rate of radon (²²²Rn) gas through porous media as a function of soil porosity/grain size and soil water content. Columns with different grain sizes, soil water content and soil depths were used. The system used solar cells photodiodes as alpha (α) detectors. This new detector is highly efficient and low cost compared to other known detectors. Soil water content was found to be the most dominant factor affecting the ²²²Rn diffusion rate. A maximum diffusion rate value of (6.5 ± 0.07) × 10⁻⁶ m²/s was found in dry conditions. The minimum diffusion value of less than (3.9 ± 0.14) × 10⁻⁷ m²/s was found in 2% soil water content. The experimental results were compared with theoretical calculations done with the "GREEN equation". Two discrepancies were observed: the time to equilibrium state in the measurements was longer compare to the calculated values and the α count rates were lower in the experiment compared with the theoretical calculations. These results can be explained by the differences in the system geometry. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Measures for the Diffusion of Solar PV are Aligned in Technology Action Plans for Six Countries in Africa

    DEFF Research Database (Denmark)

    Nygaard, Ivan; Hansen, Ulrich Elmer; Pedersen, Mathilde Brix

    2014-01-01

    Recently, development projects have provided support to governments to facilitate technology transfer for climate change adaptation and mitigation. These include the Technology Needs Assessment (TNA) funded by the Global Environmental Facility (GEF). In the TNA project, which was implemented in t...... in these six countries are used as the basis for comparing how solar PV is perceived in these countries and how policy measures enabling environmental adjustments and investment programmes are being planned to promote diffusion of the technology in these different contexts....

  14. Existence of global solutions for reaction diffusion systems modeling the electrodeposition of alloys with initial data measures

    Directory of Open Access Journals (Sweden)

    Nour Eddine Alaa

    2017-01-01

    Full Text Available In this work, we are interested in the mathematical model of reaction diffusion systems. The originality of our study is to work with concentrations appearing in reactors together with measure initial data. To validate this model, we prove the existence of global weak solutions. The "j" technique introduced by Pierre and Martin [18] is suitable for this type of solutions. However, its adaptation has some new technical difficulties that we have to overcome.

  15. Combination of pneumococcal surface protein A (PspA with whole cell pertussis vaccine increases protection against pneumococcal challenge in mice.

    Directory of Open Access Journals (Sweden)

    Maria Leonor S Oliveira

    Full Text Available Streptococcus pneumoniae is the leading cause of respiratory acute infections around the world. In Latin America, approximately 20,000 children under 5 years of age die of pneumococcal diseases annually. Pneumococcal surface protein A (PspA is among the best-characterized pneumococcal antigens that confer protection in animal models of pneumococcal infections and, as such, is a good alternative for the currently available conjugated vaccines. Efficient immune responses directed to PspA in animal models have already been described. Nevertheless, few low cost adjuvants for a subunit pneumococcal vaccine have been proposed to date. Here, we have tested the adjuvant properties of the whole cell Bordetella pertussis vaccine (wP that is currently part of the DTP (diphtheria-tetanus-pertussis vaccine administrated to children in several countries, as an adjuvant to PspA. Nasal immunization of BALB/c mice with a combination of PspA5 and wP or wP(low--a new generation vaccine that contains low levels of B. pertussis LPS--conferred protection against a respiratory lethal challenge with S. pneumoniae. Both PspA5-wP and PspA5-wP(low vaccines induced high levels of systemic and mucosal antibodies against PspA5, with similar profile, indicating no essential requirement for B. pertussis LPS in the adjuvant properties of wP. Accordingly, nasal immunization of C3H/HeJ mice with PspA5-wP conferred protection against the pneumococcal challenge, thus ruling out a role for TLR4 responses in the adjuvant activity and the protection mechanisms triggered by the vaccines. The high levels of anti-PspA5 antibodies correlated with increased cross-reactivity against PspAs from different clades and also reflected in cross-protection. In addition, passive immunization experiments indicated that antibodies played an important role in protection in this model. Finally, subcutaneous immunization with a combination of PspA5 with DTP(low protected mice against challenge with two

  16. Testing a Comprehensive Model for Measuring Problem Solving and Problem Posing Skills of Primary Pupils

    Science.gov (United States)

    Charalambous, Charalambos; Kyriakides, Leonidas; Philippou, George

    2003-01-01

    The study reported in this paper is an attempt to develop a comprehensive model of measuring problem solving and posing (PSP) skills based on Marshall's schema theory (ST). A battery of tests on PSP skills was administered to 5th and 6th grade Cypriot students (n=2519). The Rasch model was used and a scale was created for the battery of tests and…

  17. Evaluasi Desain Dan Stabilitas Kapal Penangkap Ikan Di Palabuhanratu (Studi Kasus Kapal Psp 01) Fishing Vessel Design and Stability Evaluation in Palabuhanratu (Case Study of Psp 01 Training-fishing Vessel)

    OpenAIRE

    Susanto, Adi; Iskandar, Budhi Hascaryo; Imron, Mohammad

    2011-01-01

    PSP 01 is a training-fishing vessel that was built in a traditional dock yard in Palabuhanratu, so it was not completed with design drawings and stability calculation. This paper discusses on determining the vessel's suitability of design and stability condition followed by redesign of main dimension to obtain more optimal design. Simulation carried out in various load conditions and different vessel sizes to get the considerably ideal size of the vessel. The main dimension ratio and coeffici...

  18. Automatic classification of patients with idiopathic Parkinson's disease and progressive supranuclear palsy using diffusion MRI datasets

    Science.gov (United States)

    Talai, Sahand; Boelmans, Kai; Sedlacik, Jan; Forkert, Nils D.

    2017-03-01

    Parkinsonian syndromes encompass a spectrum of neurodegenerative diseases, which can be classified into various subtypes. The differentiation of these subtypes is typically conducted based on clinical criteria. Due to the overlap of intra-syndrome symptoms, the accurate differential diagnosis based on clinical guidelines remains a challenge with failure rates up to 25%. The aim of this study is to present an image-based classification method of patients with Parkinson's disease (PD) and patients with progressive supranuclear palsy (PSP), an atypical variant of PD. Therefore, apparent diffusion coefficient (ADC) parameter maps were calculated based on diffusion-tensor magnetic resonance imaging (MRI) datasets. Mean ADC values were determined in 82 brain regions using an atlas-based approach. The extracted mean ADC values for each patient were then used as features for classification using a linear kernel support vector machine classifier. To increase the classification accuracy, a feature selection was performed, which resulted in the top 17 attributes to be used as the final input features. A leave-one-out cross validation based on 56 PD and 21 PSP subjects revealed that the proposed method is capable of differentiating PD and PSP patients with an accuracy of 94.8%. In conclusion, the classification of PD and PSP patients based on ADC features obtained from diffusion MRI datasets is a promising new approach for the differentiation of Parkinsonian syndromes in the broader context of decision support systems.

  19. Electrical transport in a disordered medium: NMR measurement of diffusivity and electrical mobility of ionic charge carriers.

    Science.gov (United States)

    Heil, S R; Holz, M

    1998-11-01

    Electrical transport in porous media plays an important role in many fields of pure and applied science. The basic microscopic processes of the charge transport have attracted considerable theoretical interest for a long time. However, on a microscopic level there was up to now no experimental access to this problem. In the present paper we demonstrate, by using a suited porous system, that two combined NMR methods can offer such a first experimental access. We apply common PFG NMR methods and the special electrophoretic NMR (ENMR) technique for the measurement of self-diffusion coefficient D+ and electric mobility u+ of a cation ((C4H9)+4) in a disordered gel-like medium (Sephadex LH-20) filled with electrolyte solution. We find a, qualitatively expected, observation time-dependence of D+, but for the first time such a time-dependence is also observed for u+, which means the detection of the phenomenon of "anomalous field assisted diffusion" or "anomalous mobility." For the measurement of the short-time behavior of the mobility a new pulse sequence is presented. The time-dependent mobilities were measured at three different external electrical fields E. From the long-time behavior of D+, u+, and DH2O three independent values for the tortuosity T of the porous system could be derived. We find equality of the tortuosities T(D+) and T(u+), which represents a first experimental proof of the validity of the Einstein relation (D+ approximately u+) in a disordered medium. Finally, we discuss advantages of the possible use of "anomalous field assisted diffusion" over the commonly used "anomalous diffusion" in morphology studies by dynamic imaging in porous media. Copyright 1998 Academic Press.

  20. The measurement of self-diffusion coefficients in liquid metals with quasielastic neutron scattering

    OpenAIRE

    Meyer, A.

    2015-01-01

    Quasielastic incoherent neutron scattering (QENS) has proven to be a versatile tool to study self diffusion of atoms in liquid metals. Here it is shown, that coherent contributions to the signal in the small q limit appear as a flat and energy independent constant to the QENS signal in single-component liquid metals even for systems with a small incoherent scattering cross section, like aluminum. Container-less processing via electromagnetic or electrostatic levitation devices, especially des...

  1. Measuring Exciton Diffusion in Conjugated Polymer Films with Super-resolution Microscopy

    Science.gov (United States)

    Penwell, Samuel; Ginsberg, Lucas; Noriega Manez, Rodrigo; Ginsberg, Naomi

    2015-03-01

    Conjugated polymers are highly tunable organic semiconductors, which can be solution processed to form thin films, making them prime candidates for organic photovoltaic devices. One of the most important parameters in a conjugated polymer solar cell is the exciton diffusion length, which depends on intermolecular couplings, and is typically on the order of 10 nm. This mean exciton migration can vary dramatically between films and within a single film due to heterogeneities in morphology on length scales of 10's to 100's nm. To study the variability of exciton diffusion and morphology within individual conjugated polymer films, we are adapting stimulated emission depletion microscopy. STED is typically used in biology with well-engineered fluorescent labels or on NV-centers in diamond. I will, however, describe how we have demonstrated STED in conjugated polymer films of MEH-PPV and CN-PPV by taking care to first understand the film's photophysical properties. This new approach provides a way to study exciton diffusion by utilizing subdiffraction optical excitation volumes. In this way, we will obtain a spatiotemporal map of exciton distributions that will help to correlate the energetic landscape to film morphology at the nanoscale. This research is supported in part by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under Contract No. DE-AC05-06.

  2. Image-Based Measurement of H2O2 Reaction-Diffusion in Wounded Zebrafish Larvae.

    Science.gov (United States)

    Jelcic, Mark; Enyedi, Balázs; Xavier, João B; Niethammer, Philipp

    2017-05-09

    Epithelial injury induces rapid recruitment of antimicrobial leukocytes to the wound site. In zebrafish larvae, activation of the epithelial NADPH oxidase Duox at the wound margin is required early during this response. Before injury, leukocytes are near the vascular region, that is, ∼100-300 μm away from the injury site. How Duox establishes long-range signaling to leukocytes is unclear. We conceived that extracellular hydrogen peroxide (H2O2) generated by Duox diffuses through the tissue to directly regulate chemotactic signaling in these cells. But before it can oxidize cellular proteins, H2O2 must get past the antioxidant barriers that protect the cellular proteome. To test whether, or on which length scales this occurs during physiological wound signaling, we developed a computational method based on reaction-diffusion principles that infers H2O2 degradation rates from intravital H2O2-biosensor imaging data. Our results indicate that at high tissue H2O2 levels the peroxiredoxin-thioredoxin antioxidant chain becomes overwhelmed, and H2O2 degradation stalls or ceases. Although the wound H2O2 gradient reaches deep into the tissue, it likely overcomes antioxidant barriers only within ∼30 μm of the wound margin. Thus, Duox-mediated long-range signaling may require other spatial relay mechanisms besides extracellular H2O2 diffusion. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  3. Time-resolved measurements of laser-induced diffusion of CO molecules on stepped Pt(111)-surfaces; Zeitaufgeloeste Untersuchung der laser-induzierten Diffusion von CO-Molekuelen auf gestuften Pt(111)-Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Lawrenz, M.

    2007-10-30

    In the present work the dynamics of CO-molecules on a stepped Pt(111)-surface induced by fs-laser pulses at low temperatures was studied by using laser spectroscopy. In the first part of the work, the laser-induced diffusion for the CO/Pt(111)-system could be demonstrated and modelled successfully for step diffusion. At first, the diffusion of CO-molecules from the step sites to the terrace sites on the surface was traced. The experimentally discovered energy transfer time of 500 fs for this process confirms the assumption of an electronically induced process. In the following it was explained how the experimental results were modelled. A friction coefficient which depends on the electron temperature yields a consistent model, whereas for the understanding of the fluence dependence and time-resolved measurements parallel the same set of parameters was used. Furthermore, the analysis was extended to the CO-terrace diffusion. Small coverages of CO were adsorbed to the terraces and the diffusion was detected as the temporal evolution of the occupation of the step sites acting as traps for the diffusing molecules. The additional performed two-pulse correlation measurements also indicate an electronically induced process. At the substrate temperature of 40 K the cross-correlation - where an energy transfer time of 1.8 ps was extracted - suggests also an electronically induced energy transfer mechanism. Diffusion experiments were performed for different substrate temperatures. (orig.)

  4. Purification and characterization of CRISP-3 from human seminal plasma and its real-time binding kinetics with PSP94.

    Science.gov (United States)

    Anklesaria, Jenifer H; Pandya, Rushika R; Pathak, Bhakti R; Mahale, Smita D

    2016-12-15

    Cysteine-rich secretory proteins (CRISPs) have been postulated to have a role in male reproduction and prostate pathophysiology. Of the mammalian CRISPs, CRISP-3 levels in particular have been shown to be upregulated in prostate cancer. Efforts have been made to obtain highly pure CRISP-3 for gaining structure-function information of this protein. However, well characterized and highly pure protein is not available yet. CRISPs from snake venom have been purified using prostate secretory protein of 94 amino acids (PSP94) has been reported earlier. In the present study, CRISP-3 was purified to homogeneity from human seminal plasma using human PSP94-immnobilized affinity column. The molecular mass of the purified protein was determined by SDS-PAGE followed by immunoblotting and found to be ∼26kDa and ∼28kDa. The purity was further verified using MALDI-TOF MS analysis, where two peaks at m/z 25509 and 27715 were obtained. The lower molecular weight peak corresponds to the calculated molecular mass of CRISP-3 (∼26kDa); whereas the higher molecular weight peak was confirmed to be the glycosylated form (∼28kDa) from the deglycosylation experiment. Binding of PSP94 in increasing concentrations to purified CRISP-3 immobilized chip was further validated using surface plasmon resonance. The kinetics data suggested that purified CRISP-3 binds specifically and with high affinity to PSP94. In conclusion, a homogeneous preparation of highly pure CRISP-3 protein is obtained from human seminal plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Spin-lattice distribution MRI maps nigral pathology in progressive supranuclear palsy (PSP during life: a pilot study.

    Directory of Open Access Journals (Sweden)

    Michael Hutchinson

    Full Text Available An MRI biomarker for Parkinsonism has long been sought, but almost all attempts at conventional field strengths have proved unsatisfactory, since patients and controls are not separated. The exception is Spin-Lattice Distribution MRI (SLD-MRI, a technique which detects changes in the substantia nigra (SN due to changes in the spin-lattice relaxation time, T1. This easily separates patients with Parkinson's disease (PD from control subjects at 1.5 Tesla, suggesting that it may be sensitive to presymptomatic disease. SLD-MRI demonstrates a topography of signal change within the SN which is the same as the known topography of pathological change, where the lateral portions of the nucleus are more affected than the medial. In a further step towards its validation, we apply SLD-MRI to a disease control, Progressive Supranuclear Palsy (PSP, the most common of the atypical forms of Parkinsonism. In PSP the topography of pathological change in the SN is reversed. We therefore hypothesized that PSP would show a topography of SLD-MRI signal change in the SN that is the reverse of PD (i.e. the medial portion is more affected than the lateral. All 7 patients showed such a topography of MR signal, and all patients were separated from control subjects. Although this is a step toward validation of SLD-MRI with respect to sensitivity and disease specificity, nevertheless we stress that this is a pilot project only. Validation will only be possible when comparing larger cohorts of PSP, PD and control subjects.

  6. Measurements of thermal conductivity and thermal diffusivity of hen egg-white lysozyme crystals using a short hot wire method

    Science.gov (United States)

    Fujiwara, Seiji; Maki, Syou; Tanaka, Seiichi; Maekawa, Ryunosuke; Masuda, Tomoki; Hagiwara, Masayuki

    2017-07-01

    Thermal conductivity and thermal diffusivity of hen egg-white lysozyme (HEWL) crystals were examined by using the transient short hot wire method. This method is based on the conventional hot wire method, but improved by using a wire that is much shorter than conventional ones. The magneto-Archimedes levitation technique was utilized to attach the HEWL crystals onto the wire. Owing to the upward magnetic force, the HEWL crystals were deposited at the air-liquid interface of the protein buffer solution where the short hot wire was preliminarily fixed. In situ observation clarified that the wire was completely buried into the HEWL crystals. By means of these techniques, the measurement of thermal conductivity and thermal diffusivity of HEWL crystals was realized for the first time. Gadolinium chloride (a paramagnetic subject) was used as a precipitant agent of crystallization. Crystal growth was carried out over 20 h at 17.2 °C. The applied magnetic field was 4 T. Measurements were conducted during the crystal growth at two different times. The thermal conductivity and diffusivity of the HEWL crystals were determined to be 0.410 W/(m.K) and 3.77×10-8 m2/s at 14 h after, and 0.438 W/(m.K) and 5.18×10-8 m2/s at 20 h after, respectively. We emphasize that this method is versatile and applicable for other protein crystals.

  7. Parallel acquisition of q-space using second order magnetic fields for single-shot diffusion measurements.

    Science.gov (United States)

    Kittler, W C; Galvosas, P; Hunter, M W

    2014-07-01

    A proof of concept is presented for the parallel acquisition of q-space under diffusion using a second order magnetic field. The second order field produces a gradient strength which varies in space, allowing a range of gradients to be applied in a single pulse, and q-space encoded into real space. With the use of a read gradient, the spatial information is regained from the NMR signal, and real space mapped onto q-space for a thin slice excitation volume. As the diffusion encoded image for a thin slice can be mapped onto q-space, and the average propagator is the inverse Fourier transform of the q-space data, it follows that the acquisition of the echo is a direct measurement of the average propagator. In the absence of a thin slice selection, the real space to q-space mapping is lost, but the ability to measure the diffusion coefficient retained with an increase in signal to noise. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Direct measurement of gas solubility and diffusivity in poly(vinylidene fluoride) with a high-pressure microbalance

    DEFF Research Database (Denmark)

    von Solms, Nicolas; Zecchin, Nicoletta; Rubin, Adam

    2005-01-01

    We present solubility and diffusion data for the gases methane and carbon dioxide in the polymer poly(vinylidene fluoride). The polymer was cut from extruded piping intended for use in offshore oil and gas applications. Measurements were carried out using a purpose-built high-pressure microbalance....... These properties were determined in the temperature range 80-120degreesC and in the pressure range 50-150bar for methane and 20-40bar for carbon dioxide. In general, good agreement was obtained for similar measurements reported in the literature. Solubility follows a Henry's law (linear) dependence with pressure...

  9. Evaluation of a fast single-photon avalanche photodiode for measurement of early transmitted photons through diffusive media.

    Science.gov (United States)

    Mu, Ying; Valim, Niksa; Niedre, Mark

    2013-06-15

    We tested the performance of a fast single-photon avalanche photodiode (SPAD) in measurement of early transmitted photons through diffusive media. In combination with a femtosecond titanium:sapphire laser, the overall instrument temporal response time was 59 ps. Using two experimental models, we showed that the SPAD allowed measurement of photon-density sensitivity functions that were approximately 65% narrower than the ungated continuous wave case at very early times. This exceeds the performance that we have previously achieved with photomultiplier-tube-based systems and approaches the theoretical maximum predicted by time-resolved Monte Carlo simulations.

  10. Optical Transient-Grating Measurements of Spin Diffusion andRelaxation in a Two-Dimensional Electron Gas

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Christopher Phillip [Univ. of California, Berkeley, CA (United States)

    2005-01-01

    Spin diffusion in n-GaAs quantum wells, as measured by our optical transient-grating technique, is strongly suppressed relative to that of charge. Over a broad range of temperatures and dopings, the suppression of Ds relative to Dc agrees quantitatively with the prediction of ''spin Coulomb dra'' theory, which takes into account the exchange of spin in electron-electron collisions. Moreover, the spin-diffusion length, Ls, is a nearly constant 1 micrometer over the same range of T and n, despite Ds's varying by nearly two orders of magnitude. This constancy supports the D'yakonov-Perel'-Kachorovskii model of spin relaxation through interrupted precessional dephasing in the spin-orbit field.

  11. Estimation of diffuse reflectance spectrum from RGB values by the synthesis of new colors for tissue measurements

    Science.gov (United States)

    Chen, Shuo; Liu, Quan

    2012-03-01

    A modified Wiener estimation method is presented for the accurate estimation of diffuse reflectance spectra from RGB values. In this method, the original RGB values are combined with a set of synthetic optical filters to generate another new three color values by using the system matrix. A modified Wiener matrix can then be created with the RGB values and the new color values, which will yield more accurate estimation because of the new color information incorporated. This method is tested on in-vivo color measurements from 200 skin sites in 10 volunteers. The results show that the proposed method improves the accuracy of the estimated diffuse reflectance spectra significantly compared with the traditional Wiener estimation method. Because of the fast computation in Wiener estimation, this method could be potentially developed for a cost effective alternative to a spectral imager.

  12. Coupling Optical and Electrical Measurements in Artificial Membranes: Lateral Diffusion of Lipids and Channel Forming Peptides in Planar Bilayers

    Directory of Open Access Journals (Sweden)

    Duclohier H

    1998-01-01

    Full Text Available Planar lipid bilayers (PLB were prepared by the Montal-Mueller technique in a FRAP system designed to simultaneously measure conductivity across, and lateral diffusion of, the bilayer. In the first stage of the project the FRAP system was used to characterise the lateral dynamics of bilayer lipids with regards to phospholipid composition (headgroup, chain unsaturation etc., presence of cholesterol and the effect of divalent cations on negatively-charged bilayers. In the second stage of the project, lateral diffusion of two fluorescently-labelled voltage-dependent pore-forming peptides (alamethicin and S4s from Shaker K+ channel was determined at rest and in the conducting state. This study demonstrates the feasibility of such experiments with PLBs, amenable to physical constraints, and thus offers new opportunities for systematic studies of structure-function relationships in membrane-associating molecules.

  13. Diagnosis of artificially induced external root resorption using conventional intraoral film radiography, CCD, and PSP: an ex vivo study.

    Science.gov (United States)

    Kamburoğlu, Kivanç; Tsesis, Igor; Kfir, Anda; Kaffe, Israel

    2008-12-01

    To compare diagnosis of artificially induced external root resorption cavities using conventional intraoral film radiography (Kodak Insight), CCD sensor (Sopix wireless) and PSP sensor (Orex Digident). Two mandibles were obtained from cadavers and teeth extracted from their alveolus. Artificial external root resorptions were simulated using ISO 0.5 mm, 0.8 mm, and 1.2 mm diameter round burs by drilling to the entire depth in different locations at the cervical, middle, and apical thirds of the proximal and buccal root surfaces of 6 teeth in increasing order. Conventional and digital radiographs were obtained from 3 different views of each tooth in 3 steps (small = 0.5 mm; medium = 0.8 mm; and large = 1.2 mm diameter round burs). Three observers examined all images for the presence of resorption cavities. In the first session, each image was evaluated separately; in the second, examiners had access to all views. Data were statistically analyzed using 4-way analysis of variance. Pair-wise comparison between receptors, projection views, size, and location were made by Tukey test. Higher proportions of correct readings were obtained with the conventional film (Kodak Insight) and CCD receptor compared with the PSP receptor used in this study (PSP intraoral film and CCD sensor produced similar results in diagnosing simulated external root resorption.

  14. Hemodynamic measurements in rat brain and human muscle using diffuse near-infrared absorption and correlation spectroscopies

    Science.gov (United States)

    Yu, Guoqiang; Durduran, Turgut; Furuya, D.; Lech, G.; Zhou, Chao; Chance, Britten; Greenberg, J. H.; Yodh, Arjun G.

    2003-07-01

    Measurement of concentration, oxygenation, and flow characteristics of blood cells can reveal information about tissue metabolism and functional heterogeneity. An improved multifunctional hybrid system has been built on the basis of our previous hybrid instrument that combines two near-infrared diffuse optical techniques to simultaneously monitor the changes of blood flow, total hemoglobin concentration (THC) and blood oxygen saturation (StO2). Diffuse correlation spectroscopy (DCS) monitors blood flow (BF) by measuring the optical phase shifts caused by moving blood cells, while diffuse photon density wave spectroscopy (DPDW) measures tissue absorption and scattering. Higher spatial resolution, higher data acquisition rate and higher dynamic range of the improved system allow us to monitor rapid hemodynamic changes in rat brain and human muscles. We have designed two probes with different source-detector pairs and different separations for the two types of experiments. A unique non-contact probe mounted on the back of a camera, which allows continuous measurements without altering the blood flow, was employed to in vivo monitor the metabolic responses in rat brain during KCl induced cortical spreading depression (CSD). A contact probe was used to measure changes of blood flow and oxygenation in human muscle during and after cuff occlusion or exercise, where the non-contact probe is not appropriate for monitoring the moving target. The experimental results indicate that our multifunctional hybrid system is capable of in vivo and non-invasive monitoring of the hemodynamic changes in different tissues (smaller tissues in rat brain, larger tissues in human muscle) under different conditions (static versus moving). The time series images of flow during CSD obtained by our technique revealed spatial and temporal hemodynamic changes in rat brain. Two to three fold longer recovery times of flow and oxygenation after cuff occlusion or exercise from calf flexors in a

  15. [A case of cerebral venous thrombosis with reversible brain parenchymal lesions: usefulness of diffusion weighted imaging and measurement of apparent diffusion coefficient].

    Science.gov (United States)

    Kuwahara, S; Abe, T; Kawada, M; Uga, S; Shimizu, K

    2001-01-01

    A 47-year-old man with a history of thrombophlebitis of his left leg for several years presented with a mild left hemiparesis and ipsilateral hypesthesia. Magnetic resonance imaging showed subacute thrombosis of the superior sagittal sinus and a cortical vein of the right cerebral hemisphere. A linear hyperintense area was found in the white matter of the right postcentral gyrus on T 2- and diffusion weighted axial imagings on the 7 days after the onset. The patient was treated conservatively, and his clinical course was uneventful. His neurological dysfunctions recovered within approximately three weeks after the onset. The white matter lesion in the right postcentral gyrus also disappeared one month later. The apparent diffusion coefficients (ADCs) in the white matter of the pre- and postcentral gyrus were measured bilaterally on the ADC mapping imaging. In the subacute stage, the ADC values in the white matter of the right pre- and postcentral gyrus were 0.50 x 10(-3) mm2/sec and 0.91 x 10(-3) mm2/sec, respectively. The %ADC indicating the ratio of ADC value of the lesion to that of the contralateral brain tissue was calculated. The %ADCs in the white matter of the pre- and postcentral gyrus were 64.9% and 124.5% respectively. In the chronic stage, the ADC values in the white matter of the right pre- and postcentral gyrus were 0.96 x 10(-3) mm2/sec and 0.99 x 10(-3) mm2/sec, and the %ADCs improved to 106.7% and 106.5% respectively. The lesions in the white matter of the right pre- and postcentral gyrus were reversible. The former was thought to be mainly ascribed to cellular edema and the latter was vasogenic edema. The present case showed when %ADC of the ischemic lesion in cerebral venous thrombosis was higher than 60%-70%, conservative therapy alone is sufficient effective for the improvement of neurological deficits.

  16. Measuring Connectivity in the Primary Visual Pathway in Human Albinism Using Diffusion Tensor Imaging and Tractography.

    Science.gov (United States)

    Grigorian, Anahit; McKetton, Larissa; Schneider, Keith A

    2016-08-11

    In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed as candidate sites for misrouting. Since a correlation between the number of lateral geniculate nucleus (LGN) relay neurons and LGN size has been shown, and based on previously reported reductions in LGN volumes in human albinism, we suggest that fiber projections from LGN to the primary visual cortex (V1) are also reduced. Studying structural differences in the visual system of albinism can improve the understanding of the mechanism of misrouting and subsequent clinical applications. Diffusion data and tractography are useful for mapping the OR (optic radiation). This manuscript describes two algorithms for OR reconstruction in order to compare brain connectivity in albinism and controls.An MRI scanner with a 32-channel head coil was used to acquire structural scans. A T1-weighted 3D-MPRAGE sequence with 1 mm(3) isotropic voxel size was used to generate high-resolution images for V1 segmentation. Multiple proton density (PD) weighted images were acquired coronally for right and left LGN localization. Diffusion tensor imaging (DTI) scans were acquired with 64 diffusion directions. Both deterministic and probabilistic tracking methods were run and compared, with LGN as the seed mask and V1 as the target mask. Though DTI provides relatively poor spatial resolution, and accurate delineation of OR may be challenging due to its low fiber density, tractography has been shown to be advantageous both in research and clinically. Tract based spatial statistics (TBSS) revealed areas of significantly reduced white matter integrity within the OR in patients with albinism compared to controls. Pairwise comparisons revealed a significant reduction in LGN to V1 connectivity in albinism compared to controls. Comparing both tracking algorithms revealed common findings, strengthening the reliability of the technique.

  17. Familias de la proteína de superficie PspA de Streptococcus pneumoniae: Relación con serotipos y localización Pneumococcal surface protein A (PspA families: Relation with serotypes and clinical site of infection

    Directory of Open Access Journals (Sweden)

    Clara Mayoral

    2010-10-01

    Full Text Available PspA, proteína de superficie de Streptococcus pneumoniae es un factor de virulencia, fuertemente inmunogénica y común a todos los serotipos. Aunque el gen que codifica para esta proteína presenta una marcada heterogeneidad en la región correspondiente al N-terminal, la PspA contiene epitopes conservados de manera tal que la inmunización genera protección contra neumococos pertenecientes a diversos tipos capsulares y con distintas PspA. A pesar del marcado polimorfismo del gen pspA es posible agrupar las distintas variantes en 3 familias mayoritarias. Estas propiedades las convierten en candidatas ideales para elaborar vacunas. Debido a que la mayoría de los trabajos sobre identificación de familias fueron realizados sobre serotipos frecuentes en otros países, el objetivo fue identificar las familias de PspA de aislamientos de pacientes de nuestra región y relacionarlas con los serotipos prevalentes y patologías. Se estudiaron 70 aislamientos, provenientes de niños con infecciones invasoras. Se aplicó una PCR utilizando cebadores específicos de cada familia. El 60% fueron familia 1 y 34% familia 2. En un 6% no se identificó ninguna de las familias de PspA. Los serotipos 1 y 5 presentaron familia 1 únicamente; los serotipos 14, 6B, 19F y 18C mostraron genes de ambas familias. La familia 1 se observó en 60% de las neumonías y 50% de las meningitis. La familia 2 en 33% de neumonías y 50% de meningitis. Esta información podría ser un valioso aporte para la formulación de una vacuna regional efectiva utilizando PspA recombinante como inmunógeno.PspA, a pneumococcal surface protein, is highly immunogenic and common to all serotypes. Although pspA gene shows a great heterogeneity at the N-terminal region, PspA protein has conserved epytopes which are able to elicit protective cross-reaction against various serotypes presenting different PspA. In spite of the high polimorfism of the PspA, three majority families can be identified

  18. Measurement of ageing effect on chloride diffusion coefficients in cementitious matrices

    Science.gov (United States)

    Andrade, C.; Castellote, M.; d'Andrea, R.

    2011-05-01

    Most of the low-level nuclear waste disposal facilities are based in engineered multi barrier systems where reinforced concrete is one of the basic materials. The calculation of the time until steel reinforcement depassivation is a need due to the demand of prediction of the service life of concrete structures in radioactive repositories. In doing that, one of the main steps is the transport of chloride ions towards the reinforcement, as one of the most aggressive agents for the rebars in concrete is chloride ions. Ageing of concrete related to chloride penetration leads to significant decrease of the "apparent diffusion" coefficient with time. If this effect is not considered, considerable bias can be introduced when predicting service life of reinforced concrete of repositories. Several effects have been addressed on their influence on the ageing of concrete, including the evolution with time of the concrete pore refinement, the binding of chlorides to the cement phases and to the changes of chloride "surface concentration". These effects have been studied in specimens made with different mixes trying to represent a wide range of mineral addition proportions. The analysis of their evolution with time has shown that the resistivity alone or the joint consideration of resistivity and binding capacity ( Cb/ Cf), are appropriate parameters to appraise the diffusivity ageing. For practical reasons, an accelerated procedure is proposed in order to calculate ageing for short periods of time.

  19. Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy

    Science.gov (United States)

    Seong, Myeongsu; Phillips, Zephaniah; Mai, Phuong Minh; Yeo, Chaebeom; Song, Cheol; Lee, Kijoon; Kim, Jae Gwan

    2016-02-01

    A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements. In order to validate the system, a flow phantom test and an arm occlusion protocol for arterial and venous occlusion were performed. Shorter exposure times (oxyhemoglobin (OHb) and deoxyhemoglobin (RHb) during arterial occlusion (max RHb=0.0085±0.0024 mM/DPF, min OHb=-0.0057±0.0044 mM/DPF). The sensitivity of the system makes it a suitable modality to observe qualitative hemodynamic trends during induced physiological changes.

  20. Development of the diffusive gradients in thin films technique for the measurement of labile gold in natural waters.

    Science.gov (United States)

    Lucas, Andrew; Rate, Andrew; Zhang, Hao; Salmon, S Ursula; Radford, Nigel

    2012-08-21

    Gold is a precious metal that exists in most soils, sediments, and natural waters at extremely low concentrations (gold, but has not been developed for this metal. This work investigates the possibility of measuring labile gold using DGT by introducing a new binding layer based on activated carbon. The performance of this new technique was assessed using gold(III) chloride in solution by: (1) determining the diffusion coefficient of gold(III) in hydrogels; (2) determining the uptake of gold(III) chloride by the new activated carbon binding layer; (3) determining an elution methodology for the binding layer and evaluating its efficiency; (4) assessing the capacity of the activated carbon binding layer to adsorb gold; (5) determining the effect of pH and ionic strength (as NaCl) on performance, and (6) assessing the selectivity of the new binding layer for gold. It was found that the diffusion coefficient of gold(III) increased as solution pH decreased. The diffusion coefficient also increased at high ionic strength (≥0.1 M NaCl). Accounting for these phenomena, the DGT technique behaved predictably under all tested conditions. The technique can potentially be used as a geochemical exploration tool for gold in soils and in aqueous environments, with method detection limits as low as 0.9 ng/L for a 7-day deployment.

  1. Measurement of long-term average carbon dioxide concentrations using passive diffusion sampling

    Science.gov (United States)

    Bertoni, Giuliano; Ciuchini, Carla; Tappa, Remo

    A diffusive sampling device is proposed for long-term determination of average airborne concentration of CO 2 in urban and industrial areas, as well as in indoor sites. A hydro-alcoholic barium hydroxide solution is employed as a CO 2 reagent sink. The analytical method is based on the determination of the solute barium hydroxide remained after the acid-base reaction, in which its insoluble carbonate salt precipitates. Indoor laboratory experiments show that this technique exhibits a good precision and reproducibility. A 6-week internal consistency test demonstrates that this device has a constant uptake rate, allowing us to propose it as a suitable and inexpensive tool in performing the monitoring of urban and industrial sites over long periods and in indoor-outdoor studies, like those involved in the sick-building syndrome problem.

  2. Impact of blood volume changes within the human skin on the diffuse reflectance measurements in visible and NIR spectral ranges

    Science.gov (United States)

    Zherebtsov, Evgeny; Bykov, Alexander; Popov, Alexey; Doronin, Alexander; Meglinski, Igor

    2017-03-01

    We consider changes in the volume of blood and oxygen saturation caused by a pulse wave and their influence on the diffuse reflectance spectra in the visible/NIR spectral range. CUDA-based Monte-Carlo model was used for routine simulation of detector depth sensitivity (sampling volume) and skin spectra, and their variations associated with physiological changes in the human skin. The results presented in the form of animated graphs of sampling volume changes for scaling of the parameters of the main human skin layers related to the results of experimental measurements are of particular interest for pulse oximetry, photoplethysmography, Doppler flowmetry, reflectance spectroscopy.

  3. Electrochemical measurements of diffusion coefficients and activity coefficients for MnCl2 in molten eutectic LiCl-KCl

    Science.gov (United States)

    Horvath, D.; Rappleye, D.; Bagri, P.; Simpson, M. F.

    2017-09-01

    An electrochemical study of manganese chloride in molten salt mixtures of eutectic LiCl-KCl was carried out using a variety of electrochemical methods in a high temperature cell including cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA), and open circuit potentiometry. Single step reduction from Mn2+ to Mn(0) was observed on both W and Mo working electrodes. Using a combination of these methods, measurements were made of activity coefficient and diffusion coefficient for MnCl2 in LiCl-KCl as a function of concentration (3.54 × 10-4 to 3.60 × 10-3 mol fraction of MnCl2) at 773K. From OCP measurements, values for activity coefficient varied from 0.014 to 0.0071. Diffusion coefficients varied with concentration and differed based on measurement method (CV, CA, or CP). Based on cyclic Mn(II) ranged from 1.1 to 2.8 × 10-5 cm2/s depending on concentration.

  4. Determination of the Ability to Measure Traces of Water in Dehydrated Residues of Waste Water by IR Diffuse Reflectance Spectra

    Science.gov (United States)

    Pratsenka, S. V.; Voropai, E. S.; Belkin, V. G.

    2018-01-01

    Rapid measurement of the moisture content of dehydrated residues is a critical problem, the solution of which will increase the efficiency of treatment facilities and optimize the process of applying flocculants. The ability to determine the moisture content of dehydrated residues using a meter operating on the IR reflectance principle was confirmed experimentally. The most suitable interference filters were selected based on an analysis of the obtained diffuse reflectance spectrum of the dehydrated residue in the range 1.0-2.7 μm. Calibration curves were constructed and compared for each filter set. A measuring filter with a transmittance maximum at 1.19 μm and a reference filter with a maximum at 1.3 μm gave the best agreement with the laboratory measurements.

  5. Corrigendum to “Convergence of invariant measures for singular stochastic diffusion equations” [Stochastic Process. Appl. 122 (2012) 1998–2017

    OpenAIRE

    Ciotir, Ioana; Tölle, Jonas M.

    2013-01-01

    We correct a few errors that appeared in [Convergence of invariant measures for singular stochastic diffusion equations, Stochastic Process. Appl. 122 (2012), no. 4, 1998--2017] by I. Ciotir and J.M. T\\"olle.

  6. Blood flow measurement of human skeletal muscle during various exercise intensity using diffuse correlation spectroscopy (DCS)

    Science.gov (United States)

    Murakami, Yuya; Ono, Yumie; Ichinose, Masashi

    2017-02-01

    We studied blood flow dynamics of active skeletal muscle using diffuse correlation spectroscopy (DCS), an emerging optical modality that is suitable for noninvasive quantification of microcirculation level in deep tissue. Seven healthy subjects conducted 0.5 Hz dynamic handgrip exercise for 3 minutes at intensities of 10, 20, 30, and 50 % of maximal voluntary contraction (MVC). DCS could detect the time-dependent increase of the blood flow response of the forearm muscle for continuous exercises, and the increase ratios of the mean blood flow through the exercise periods showed good correlation with the exercise intensities. We also compared blood flow responses detected from DCS with two different photon sampling rates and found that an appropriate photon sampling rates should be selected to follow the wide-ranged increase in the muscle blood flow with dynamic exercise. Our results demonstrate the possibility for utilizing DCS in a field of sports medicine to noninvasively evaluate the dynamics of blood flow in the active muscles.

  7. Experimental Measurement of Diffusive Extinction Depth and Soil Moisture Gradients in Southwestern Saudi Arabian Dune Sand

    KAUST Repository

    Mughal, Iqra

    2013-05-01

    In arid lands, a major contribution to water loss is by soil water evaporation. Desert sand dunes in arid regions are devoid of runoff and have high rates of infiltration. Rainwater is commonly stored within them because of the low permeability soils in the underlying desert pavement. In such cases, moisture is confined in the sand dune below a depth, termed as the “extinction depth”, where it is protected from evaporation during long dry periods. Moreover, desert sand dunes have sparse vegetation, which results in low transpiration losses from the stored water. The water accumulated below the extinction depth of the sand dunes can be utilized for various purposes such as in irrigation to support desert agriculture. In this study, field experiments were conducted in Western Saudi Arabia to monitor the soil moisture gradients and determine the diffusive extinction depth of dune sand. The dune sand was saturated with water and was exposed to natural conditions (evaporation and precipitation). The decline of the water level in the sand column was continuously recorded using transducers and sensors installed at different depths monitored the temporal variation of temperature and moisture content within the sand. The hydrological simulator HYDRUS-1D was used to construct the vertical profiles of soil water content and temperature and the results obtained from HYDRUS-1D were compared to the gradients monitored by the sensors.

  8. Familias de la proteína de superficie PspA de Streptococcus pneumoniae: Relación con serotipos y localización

    Directory of Open Access Journals (Sweden)

    Clara Mayoral

    2010-10-01

    Full Text Available PspA, proteína de superficie de Streptococcus pneumoniae es un factor de virulencia, fuertemente inmunogénica y común a todos los serotipos. Aunque el gen que codifica para esta proteína presenta una marcada heterogeneidad en la región correspondiente al N-terminal, la PspA contiene epitopes conservados de manera tal que la inmunización genera protección contra neumococos pertenecientes a diversos tipos capsulares y con distintas PspA. A pesar del marcado polimorfismo del gen pspA es posible agrupar las distintas variantes en 3 familias mayoritarias. Estas propiedades las convierten en candidatas ideales para elaborar vacunas. Debido a que la mayoría de los trabajos sobre identificación de familias fueron realizados sobre serotipos frecuentes en otros países, el objetivo fue identificar las familias de PspA de aislamientos de pacientes de nuestra región y relacionarlas con los serotipos prevalentes y patologías. Se estudiaron 70 aislamientos, provenientes de niños con infecciones invasoras. Se aplicó una PCR utilizando cebadores específicos de cada familia. El 60% fueron familia 1 y 34% familia 2. En un 6% no se identificó ninguna de las familias de PspA. Los serotipos 1 y 5 presentaron familia 1 únicamente; los serotipos 14, 6B, 19F y 18C mostraron genes de ambas familias. La familia 1 se observó en 60% de las neumonías y 50% de las meningitis. La familia 2 en 33% de neumonías y 50% de meningitis. Esta información podría ser un valioso aporte para la formulación de una vacuna regional efectiva utilizando PspA recombinante como inmunógeno.

  9. Lung diffusion testing

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003854.htm Lung diffusion testing To use the sharing features on this page, please enable JavaScript. Lung diffusion testing measures how well the lungs exchange gases. This ...

  10. Transferring the calibration of direct solar irradiance to diffuse-sky radiance measurements for CIMEL Sun-sky radiometers.

    Science.gov (United States)

    Li, Zhengqiang; Blarel, Luc; Podvin, Thierry; Goloub, Philippe; Buis, Jean-Pierre; Morel, Jean-Philippe

    2008-04-01

    Two types of sunphotometric measurement are considered in this study: direct-Sun irradiance and diffuse-sky radiance. Based on CIMEL CE318 Sun-sky radiometer characteristics, we introduce a gain-corrected solid angle that allows interconverting calibration coefficients of these two types of measurement, thus realizing a "vicarious" radiance calibration. The accuracy of the gain-corrected solid angle depends on the number of available historical calibration records. The method is easy to use, provided that at least one laboratory calibration has been made previously. Examples coming from three distinct CE318 versions belonging to the AERONET/PHOTONS network are presented to provide details on the vicarious calibration method and protocols. From the error propagation analysis and the comparison with laboratory results, the uncertainty of the vicarious radiance calibration is shown to be comparable with the laboratory one, e.g., 3%-5%.

  11. Anisotropy of collagen fibre alignment in bovine cartilage: comparison of polarised light microscopy and spatially resolved diffusion-tensor measurements.

    Science.gov (United States)

    de Visser, S K; Bowden, J C; Wentrup-Byrne, E; Rintoul, L; Bostrom, T; Pope, J M; Momot, K I

    2008-06-01

    To compare collagen fibre alignment angles obtained from polarised light microscopy (PLM) and diffusion-tensor imaging (DTI) in bovine articular cartilage. Five samples of bovine articular cartilage from five different animals were studied using magnetic resonance imaging and PLM techniques. T(2)-weighted, diffusion-tensor (DT), and PLM images were acquired for each sample and average depth profiles of the PLM and DTI angles, as well as the banding patterns observed in T(2)-weighted magnetic resonance (MR) images, were compared. Statistical properties of the distributions of the DTI and PLM angles were examined. The samples exhibited a range of alignment morphologies. In the samples with the "conventional" three-zone alignment pattern, a correlation between the PLM and DTI alignment zones and the banding in T(2)-weighted MR images was observed. The shapes of the depth profiles of the PLM and DTI alignment angles were qualitatively similar for each sample. Three samples showed good quantitative correlation between the DT and PLM alignment angles. The correlation between the diffusion and PLM alignment angles was best in the regions of low degree of disorder of fibre alignment. This study provides the first quantitative comparison of DTI of cartilage with the more established PLM techniques. The correlation between alignment angles derived from PLM and DTI data was evident across a wide range of alignment morphologies. The results support the use of DTI for the quantitative measurement of collagen fibre alignment. The microscopic-scale (~10 microm) dispersion of fibre alignment angles appears to be an important factor for understanding the extent of quantitative correlation between PLM and DTI results.

  12. Structure and Permeability of Porous Silicon Investigated by Self-Diffusion NMR Measurements of Ethanol and Heptane

    Directory of Open Access Journals (Sweden)

    Puibasset J.

    2016-07-01

    Full Text Available The adsorption and phase transitions of confined fluids in nanoporous materials have been studied intensely because of both their fundamental interest and their crucial role in many technologies. Questions relating to the influence of the confinement of fluids, and the disorder or elastic deformation of porous solids on the liquid-gas phase transition are still under debate. Model systems are needed to understand the adsorption phenomenon. In this context, Porous Silicon (PoSi, which is a single crystal obtained by etching a (100 silicon wafer is an excellent candidate. Indeed, it consists of non-connected tubular pores running parallel to the [100] axis perpendicular to the wafer surface, with transverse sections with a polygonal shape of nanometric size whose areas are widely distributed. Once detached from the wafer, free PoSi membranes can be considered a nanoscale disordered honeycomb. Adsorption/desorption experiments have been performed to characterize the structure: they have shown that evaporation occurs collectively, an intriguing observation generally associated with a disordered pore structure with many interconnections through narrow necks. The characterization of fluid mobility inside the pores should give complementary information about the pore structure and topology. This paper focuses on the dynamics of a fluid confined inside the structure of porous silicon, and in particular the self-diffusion measurements (pulsed field gradient spin echo Nuclear Magnetic Resonance (NMR. The results show a strong anisotropy of the self-diffusion tensor, as expected in this highly anisotropic structure. However, a non-zero self-diffusion in the directions perpendicular to the pore axis is observed. In order to interpret these puzzling results, molecular and Brownian dynamics calculations are underway.

  13. The effect of diffusion and susceptibility differences on T2 measurements for fluids in porous media and biological tissues.

    Science.gov (United States)

    Borgia, G C; Brown, R J; Fantazzini, P

    1996-01-01

    A number of features of T2 measurements for fluids in porous media have shown behavior contrary to that suggested by intuition developed in other areas. For porous media with relatively uniform pore spaces the following have been observed, in each case for certain ranges only of Xv (susceptibility difference times frequency), D (diffusion coefficient), a (a pore dimension), porespace shape and distribution, echo-time t for single echoes and half-echo-spacing tau for CPMG): (1) In S(t) for FID (free induction decay, S for signal) with constant slope after an initial period of increasing slope; (2) In Ss(t) for single (subscript s) echoes linear (instead of cubic) in t after an initial period; (3) for CPMG R(tau) = 1/T2(tau) - 1/T2(tau-->0) linear in tau over a substantial range; (4) slope of R(tau) independent of D and alpha for this range; (5) slope R(s) of In Ss(t) independent of D and a, and (6) R(s)(t) and R(tau) at long times linear (instead of quadratic) in Xv. These features appear to be compatible with the assumption of a truncated Cauchy-Lorentz distribution of the local magnetic fields due to susceptibility differences. The statistics of repeated sampling of local fields in different parts of the porespace during diffusion lead to a suppression, after a short time, of the effects of diffusion on the FID decay rate and the single-echo decay rate over significant ranges of the parameters. Data are presented to extend the range of parameters studied previously.

  14. Increasing the sensitivity of NMR diffusion measurements by paramagnetic longitudinal relaxation enhancement, with application to ribosome–nascent chain complexes

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Sammy H. S.; Waudby, Christopher A.; Cassaignau, Anaïs M. E.; Cabrita, Lisa D.; Christodoulou, John, E-mail: j.christodoulou@ucl.ac.uk [University College London and Birkbeck College, Institute of Structural and Molecular Biology (United Kingdom)

    2015-10-15

    The translational diffusion of macromolecules can be examined non-invasively by stimulated echo (STE) NMR experiments to accurately determine their molecular sizes. These measurements can be important probes of intermolecular interactions and protein folding and unfolding, and are crucial in monitoring the integrity of large macromolecular assemblies such as ribosome–nascent chain complexes (RNCs). However, NMR studies of these complexes can be severely constrained by their slow tumbling, low solubility (with maximum concentrations of up to 10 μM), and short lifetimes resulting in weak signal, and therefore continuing improvements in experimental sensitivity are essential. Here we explore the use of the paramagnetic longitudinal relaxation enhancement (PLRE) agent NiDO2A on the sensitivity of {sup 15}N XSTE and SORDID heteronuclear STE experiments, which can be used to monitor the integrity of these unstable complexes. We exploit the dependence of the PLRE effect on the gyromagnetic ratio and electronic relaxation time to accelerate recovery of {sup 1}H magnetization without adversely affecting storage on N{sub z} during diffusion delays or introducing significant transverse relaxation line broadening. By applying the longitudinal relaxation-optimized SORDID pulse sequence together with NiDO2A to 70S Escherichia coli ribosomes and RNCs, NMR diffusion sensitivity enhancements of up to 4.5-fold relative to XSTE are achieved, alongside ∼1.9-fold improvements in two-dimensional NMR sensitivity, without compromising the sample integrity. We anticipate these results will significantly advance the use of NMR to probe dynamic regions of ribosomes and other large, unstable macromolecular assemblies.Graphical Abstract.

  15. Measurements on, and modelling of diffusive and advective radon transport in soil

    DEFF Research Database (Denmark)

    Graff, E.R. van der; Witteman, G.A.A.; Spoel, W.H. van der

    1994-01-01

    Results are presented of measurements on radon transport in soil under controlled conditions with a laboratory facility consisting of a stainless steel vessel (height and diameter 2 m) filled with a uniform column of sand. At several depths under the sand surface, probes are radially inserted...... into the vessel to measure the radon concentration in the soil gas. To study advective radon transport a perforated circular box is placed in the sand close to the bottom of the vessel. By pressurising this box, an air flow through the sand column is induced. Radon concentration profiles were measured without...... an air flow as a function of time, and for several values of the air flow, equilibrium radon concentration profiles were measured....

  16. Modified Wiener estimation of diffuse reflectance spectra from RGB values by the synthesis of new colors for tissue measurements

    Science.gov (United States)

    Chen, Shuo; Liu, Quan

    2012-03-01

    We present a new method for the accurate estimation of diffuse reflectance spectra from RGB values based on Wiener estimation. In the proposed method, a system matrix obtained from the original RGB values is combined with a set of synthetic optical filters to generate another three values corresponding to new colors. A modified Wiener matrix can then be created with the original RGB values and the new color values, which will yield a more accurate estimation because of the new color information that has been incorporated. This method was tested on in vivo color measurements from 200 skin sites in 10 volunteers. The results show that the proposed method is able to improve the estimation accuracy significantly compared with the traditional Wiener estimation method. The fast speed of this method may enable the estimation of diffuse reflectance spectra at multiple tissue locations from color images in real time, which provides a cost-effective alternative to spectral imaging with the additional advantage of high spectral resolution.

  17. End-of-Fill Diffusion and Halo Population Measurements with Physics Beams at 6.5 TeV

    CERN Document Server

    Valentino, Gianluca; Gorzawski, Arkadiusz; Redaelli, Stefano; Trad, Georges; Wagner, Joschka; Xu, Chen; CERN. Geneva. ATS Department

    2017-01-01

    Beam halo measurements at 6.5 TeV in the LHC were conducted with a full physics beam via collimator scrapings in end-of-fill MDs carried out in May and July 2016. From the time evolution of the beam losses in a collimator scan, it is possible to extract information on the halo diffusion and population. In the first MD, six scans were performed with two collimators in the vertical and horizontal planes in B1 and B2 respectively. The scans were done with squeezed colliding beams, with and without a gentle continuous transverse blow-up with the ADT (transverse damper) on a non-colliding bunch train. In the second MD, four scans were performed with the same collimators with squeezed colliding beams. The beam losses observed with the standard ionization chamber BLMs are compared to the diamond BLMs, and parametric fits of the diffusion model are applied to temporal loss patterns from colliding and non-colliding bunch trains. The results presented in this note also include the particle escape times and frequency an...

  18. Dark Matter implications of the Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background: Status report

    Energy Technology Data Exchange (ETDEWEB)

    Fornasa, Mattia, E-mail: fornasam@gmail.com [Instituto de Astrofisica de Andalucia - CSIC, Glorieta de la Astronomia, E-18008, Granada (Spain); Zavala, Jesus [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo (Canada); Sanchez-Conde, Miguel A. [KIPAC - SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Prada, Francisco [Instituto de Astrofisica de Andalucia - CSIC, Glorieta de la Astronomia, E-18008, Granada (Spain); Vogelsberger, Mark [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

    2012-11-11

    For the first time, the Fermi-LAT measured the angular power spectrum (APS) of anisotropies in the diffuse gamma-ray background. The data is found to be broadly compatible with a model with contributions from the point sources in the 1-yr catalog, the galactic diffuse background, and the extragalactic isotropic emission; however, deviations are present at both large and small angular scales. In this study, we complement the model with a contribution from Dark Matter (DM) whose distribution is modeled exploiting the results of the most recent N-body simulations, considering the contribution of extragalactic halos and subhalos (from Millennium-II) and of galactic substructures (from Aquarius). With the use of the Fermi Science Tools, these simulations serve as templates to produce mock gamma-ray count maps for DM gamma-ray emission, both in the case of an annihilating and a decaying DM candidate. The APS will then be computed and compared with the Fermi-LAT results to derive constraints on the DM particle physics properties. The possible systematic due to an imperfect model of the galactic foreground is also studied and taken into account properly. The present paper reports on the status of the project.

  19. Long Term Sorption Diffusion Experiment (LTDE-SD). Performance of main in situ experiment and results from water phase measurements

    Energy Technology Data Exchange (ETDEWEB)

    Widestrand, Henrik; Byegaard, Johan; Nilsson, Kersti; Hoeglund, Susanne; Gustafsson, Erik (Geosigma AB, Uppsala (Sweden)); Kronberg, Magnus (Swedish Nuclear Fuel and Waste Management Co. (Sweden))

    2010-12-15

    radionuclide sorption to colloids in the aqueous phase was of minor importance. Furthermore, the measurements performed after a general colloid filtration showed no significant concentrations of inorganic colloids. The natural redox conditions were difficult to maintain during the experiment. Therefore the experiment was performed under the oxidizing conditions (E{sub h} approx470 mV) that was obtained during the circulation of the groundwater. Sorption occurred on equipment during the experiment, in particular for some surface complexation sorbing tracers, possibly due to iron-oxy-hydroxides formed on equipment surfaces. Quantification was made of the amount of sorption on the equipment in order to enable corrections in the evaluation procedures. The sorption occurring for ion-exchange sorbing tracers was concluded to predominately be an effect of interaction with the geologic material since the sorbed amount on the equipment was found to be insignificant. Natural pressure conditions were maintained throughout the experiment time and consequently penetration into the rock matrix must be considered as a result only of diffusion since no advection could have been involved. Modelling in order to determine sorption coefficients (K{sub a}, K{sub d}) was performed using a homogeneous porosity sorption-diffusion model using fixed data for porosity and matrix diffusivity from laboratory investigations on LTDE-SD core materials. For the ion-exchange sorbing tracers, the in situ evaluated K{sub d} was in the range of the batch sorption results or near the highest values (fracture material) from the batch sorption results. This indicates that a sorption-diffusion model can describe the concentration losses reasonably well for the ion-exchange sorbing tracers. However, due to the sorption on equipment, one should treat these results with care and consider the analysis of the sampled rock material before any definitive conclusions can be made based on the actual penetration profiles of

  20. A numerical-statistical approach to determining the representative elementary volume (REV of cement paste for measuring diffusivity

    Directory of Open Access Journals (Sweden)

    Zhang, M. Z.

    2010-12-01

    Full Text Available Concrete diffusivity is a function of its microstructure on many scales, ranging from nanometres to millimetres. Multi-scale techniques are therefore needed to model this parameter. Representative elementary volume (REV, in conjunction with the homogenization principle, is one of the most common multi-scale approaches. This study aimed to establish a procedure for establishing the REV required to determine cement paste diffusivity based on a three-step, numerical-statistical approach. First, several series of 3D cement paste microstructures were generated with HYMOSTRUC3D, a cement hydration and microstructure model, for different volumes of cement paste and w/c ratios ranging from 0.30 to 0.60. Second, the finite element method was used to simulate the diffusion of tritiated water through these microstructures. Effective cement paste diffusivity values for different REVs were obtained by applying Fick’s law. Finally, statistical analysis was used to find the fluctuation in effective diffusivity with cement paste volume, from which the REV was then determined. The conclusion drawn was that the REV for measuring diffusivity in cement paste is 100x100x100 μm3.

    La difusividad del hormigón depende de su microestructura a numerosas escalas, desde nanómetros hasta milímetros, por lo que se precisa de técnicas multiescala para representar este parámetro. Junto con el principio de homogeneización, uno de los métodos multiescala más habituales es el volumen elemental representativo (VER. El objeto de este estudio era establecer un procedimiento que permitiera determinar el VER necesario para calcular la difusividad de la pasta de cemento, basándose en un método numéricoestadístico que consta de tres etapas. Primero, se crearon varias series de microestructuras de pasta de cemento en 3D con HYMOSTRUC3D, un programa que permite crear un modelo de la hidratación y microestructura del cemento. Luego se empleó el método de

  1. Redox characterization of semiconductors based on electrochemical measurements combined with UV-Vis diffuse reflectance spectroscopy.

    Science.gov (United States)

    Świętek, Elżbieta; Pilarczyk, Kacper; Derdzińska, Justyna; Szaciłowski, Konrad; Macyk, Wojciech

    2013-09-14

    Several techniques can be applied to characterize redox properties of wide bandgap semiconductors, however some of them are of limited use. In this paper we propose a new modification of the old spectroelectrochemical method developed two decades ago. A procedure based on measurements of the reflectance changes as a function of potential applied to the electrode coated with the studied material appears to be a very convenient tool for characterizing redox properties of semiconductors, forming either transparent or opaque films at a platinum electrode. A discussion on the measured redox parameters of semiconductor films concludes with a definition of a new term, the absorption onset potential of the material.

  2. Accelerating inference for diffusions observed with measurement error and large sample sizes using approximate Bayesian computation

    DEFF Research Database (Denmark)

    Picchini, Umberto; Forman, Julie Lyng

    2016-01-01

    a nonlinear stochastic differential equation model observed with correlated measurement errors and an application to protein folding modelling. An approximate Bayesian computation (ABC)-MCMC algorithm is suggested to allow inference for model parameters within reasonable time constraints. The ABC algorithm...

  3. Anisotropies in the Diffuse Gamma-Ray Background Measured by the Fermi LAT

    Science.gov (United States)

    2012-05-02

    VIH respectively. We note that the associated measurement uncertainties can be taken to be Gaussian, in which case the reported significance quantifies...interest. The analysis of the simulated isotropic component, pre- sented in Sec. VIH , provides another means of assessing the impact of the mask on the

  4. Comparison of measured and satellite-derived spectral diffuse attenuation coefficients for the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Talaulikar, M.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.

    , 555 and 670 nm, respectively. This profile corresponds to a chlorophyll value of about 1 mg m sup(−3). The maximum values of the measured Kd correspond to waters with chlorophyll of about 8 mg m sup(−3). Though the satellite-derived Kd...

  5. MEASUREMENTS ON, AND MODELING OF DIFFUSIVE AND ADVECTIVE RADON TRANSPORT IN SOIL

    NARCIS (Netherlands)

    VANDERGRAAF, ER; WITTEMAN, GAA; VANDERSPOEL, WH; ANDERSEN, CE; DEMEIJER, RJ

    1994-01-01

    Results are presented of measurements on radon transport in soil under controlled conditions with a laboratory facility consisting of a stainless steel vessel (height and diameter 2 m) filled with a uniform column of sand. At several depths under the sand surface, probes are radially inserted into

  6. Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy.

    Science.gov (United States)

    Seong, Myeongsu; Phillips, Zephaniah; Mai, Phuong Minh; Yeo, Chaebeom; Song, Cheol; Lee, Kijoon; Kim, Jae Gwan

    2016-02-01

    A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements. In order to validate the system, a flow phantom test and an arm occlusion protocol for arterial and venous occlusion were performed. Shorter exposure times (<1 ms ) show a higher drop (between 50% and 66%) and recovery of 1/K²S values after occlusion (approximately 150%), but longer exposure time (3 ms) shows more consistent hemodynamic changes. For four subjects, the 1/K²S values dropped to an average of 82.1±4.0% during the occlusion period and the average recovery of 1/K²S values after occlusion was 109.1±0.8% . There was also an approximately equivalent amplitude change in oxyhemoglobin (OHb) and deoxyhemoglobin (RHb) during arterial occlusion (max RHb=0.0085±0.0024 mM/DPF, min OHb=-0.0057±0.0044 mM/DPF). The sensitivity of the system makes it a suitable modality to observe qualitative hemodynamic trends during induced physiological changes.

  7. Implications of the Fermi-LAT diffuse gamma-ray measurements on annihilating or decaying dark matter

    Science.gov (United States)

    Hütsi, Gert; Hektor, Andi; Raidal, Martti

    2010-07-01

    We analyze the recently published Fermi-LAT diffuse gamma-ray measurements in the context of leptonically annihilating or decaying dark matter (DM) with the aim to explain simultaneously the isotropic diffuse gamma-ray and the PAMELA, Fermi and HESS (PFH) anomalous e± data. Five different DM annihilation/decay channels 2e, 2μ, 2τ, 4e, or 4μ (the latter two via an intermediate light particle phi) are generated with PYTHIA. We calculate both the Galactic and extragalactic prompt and inverse Compton (IC) contributions to the resulting gamma-ray spectra. To find the Galactic IC spectra we use the interstellar radiation field model from the latest release of GALPROP. For the extragalactic signal we show that the amplitude of the prompt gamma-emission is very sensitive to the assumed model for the extragalactic background light. For our Galaxy we use the Einasto, NFW and cored isothermal DM density profiles and include the effects of DM substructure assuming a simple subhalo model. Our calculations show that for the annihilating DM the extragalactic gamma-ray signal can dominate only if rather extreme power-law concentration-mass relation C(M) is used, while more realistic C(M) relations make the extragalactic component comparable or subdominant to the Galactic signal. For the decaying DM the Galactic signal always exceeds the extragalactic one. In the case of annihilating DM the PFH favored parameters can be ruled out by gamma-ray constraints only if power-law C(M) relation is assumed. For DM decaying into 2μ or 4μ the PFH favored DM parameters are not in conflict with the gamma-ray data. We find that, due to the (almost) featureless Galactic IC spectrum and the DM halo substructure, annihilating DM may give a good simultaneous fit to the isotropic diffuse gamma-ray and to the PFH e± data without being in clear conflict with the other Fermi-LAT gamma-ray measurements.

  8. Diffuse optical measurements of head and neck tumor hemodynamics for early prediction of radiation therapy (Conference Presentation)

    Science.gov (United States)

    Dong, Lixin; Kudrimoti, Mahesh; Irwin, Daniel; Chen, Li; Shang, Yu; Li, Xingzhe; Stevens, Scott D.; Shelton, Brent J.; Yu, Guoqiang

    2016-03-01

    Radiation therapy is a principal modality for head and neck cancers and its efficacy depends on tumor hemodynamics. Our laboratory developed a hybrid diffuse optical instrument allowing for simultaneous measurements of tumor blood flow and oxygenation. In this study, the clinically involved cervical lymph node was monitored by the hybrid instrument once a week over the treatment period of seven weeks. Based on treatment outcomes within one year, patients were classified into a complete response group (CR) and an incomplete response group (IR) with remote metastasis and/or local recurrence. A linear mixed models was used to compare tumor hemodynamic responses to the treatment between the two groups. Interestingly, we found that human papilloma virus (HPV-16) status largely affected tumor hemodynamic responses. For HPV-16 negative tumors, significant differences in blood flow index (BFI, p = 0.007) and reduced scattering coefficient (μs', p = 0.0005) were observed between the two groups; IR tumors exhibited higher μs' values and a continuous increase in BFI over the treatment period. For HPV-16 positive tumors, oxygenated hemoglobin concentration ([HbO2]) and blood oxygen saturation (StO2) were significant different (p = 0.003 and 0.01, respectively); IR group showed lower [HbO2] and StO2. Our results imply HPV-16 negative tumors with higher density of vasculature (μs') and higher blood flow show poor responses to radiotherapy and HPV-16 positive tumors with lower tissue oxygenation level (lower StO2 and [HbO2]) exhibit poor treatment outcomes. Our diffuse optical measurements show the great potential for early prediction of radiotherapy in head and neck cancers.

  9. A new tool for direct non-invasive evaluation of chlorophyll a content from diffuse reflectance measurements.

    Science.gov (United States)

    Muñoz-Ortuño, M; Serra-Mora, P; Herráez-Hernández, R; Verdú-Andrés, J; Campíns-Falcó, P

    2017-12-31

    Chlorophyll is a key biochemical component that is responsible for photosynthesis and is an indicator of plant health. The effect of stressors can be determined by measuring the amount of chlorophyll a, which is the most abundant chlorophyll, in vegetation in general. Nowadays, invasive methods and vegetation indices are used for establishing chlorophyll amount or an approximation to this value, respectively. This paper demonstrates that H-point curve isolation method (HPCIM) is useful for isolating the signal of chlorophyll a from non-invasive diffuse reflectance measurements of leaves. Spinach plants have been chosen as an example. For applying the HPCIM only the registers of both, a standard and the sample are needed. The results obtained by HPCIM and the invasive method were statistically similar for spinach leaves: 144±6mg/m(2) (n=5) and 155±40mg/m(2) (n=5), respectively. However, more precise values were achieved with the HPCIM, which also involved minimal experimental effort. The HPCIM method was applied to spinach plants stressed by the action of several pesticides and water scarcity, showing a decrease of chlorophyll a content with time, which is related with a loss of health. The results obtained were compared with those achieved by two different reflectance vegetation indices (Macc01 and NDVI). Although NDVI and HPCIM gave similar footprints for the plants tested, vegetation indices fail in the estimation of real content of the chlorophyll a. The HPCIM could contribute to improve the knowledge of the chlorophyll a content of vegetation like health indicator, by applying it to a much employed non-invasive technique such as diffuse reflectance, which can be used in place or in remote sensing mode. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Retinal degeneration in progressive supranuclear palsy measured by optical coherence tomography and scanning laser polarimetry.

    Science.gov (United States)

    Stemplewitz, Birthe; Kromer, Robert; Vettorazzi, Eik; Hidding, Ute; Frings, Andreas; Buhmann, Carsten

    2017-07-13

    This cross-sectional study compared the retinal morphology between patients with progressive supranuclear palsy (PSP) and healthy controls. (The retinal nerve fiber layer (RNFL) around the optic disc and the retina in the macular area of 22 PSP patients and 151 controls were investigated by spectral domain optical coherence tomography (SD-OCT). Additionally, the RNFL and the nerve fiber index (NFI) were measured by scanning laser polarimetry (SLP). Results of RNFL measurements with SD-OCT and SLP were compared to assess diagnostic discriminatory power. Applying OCT, PSP patients showed a smaller RNFL thickness in the inferior nasal and inferior temporal areas. The macular volume and the thickness of the majority of macular sectors were reduced compared to controls. SLP data showed a thinner RNFL thickness and an increase in the NFI in PSP patients. Sensitivity and specificity to discriminate PSP patients from controls were higher applying SLP than SD-OCT. Retinal changes did not correlate with disease duration or severity in any OCT or SLP measurement. PSP seems to be associated with reduced thickness and volume of the macula and reduction of the RNFL, independent of disease duration or severity. Retinal imaging with SD-OCT and SLP might become an additional tool in PSP diagnosis.

  11. Evaluation of Lithophysal Conductivity, Diffusivity, and Porosity Measurements Using the REKA Method

    Energy Technology Data Exchange (ETDEWEB)

    Danko, G.; Shah, N.; Bahrami, D.

    2002-02-26

    A method is presented, based on the NUFT and REKA V1.1 software packages combination, to study the nature of non-steady-state heat flow during a single-borehole REKA thermal probe thermophysical measurement in solid as well as lithophysal rock formation. The results prove the principle of the REKA method application in lithophysal formation. The numerical evaluation results, based on the use of two qualified software packages, show that the presented REKA probe arrangement is correctly modeled and that the effective heat conductivity and the lithophysal porosity can be evaluated correctly using the REKA probe method.

  12. Setup of a bench for short time laser flash diffusivity measurement; Mise en place d`un banc de mesure de diffusivite flash laser aux temps courts

    Energy Technology Data Exchange (ETDEWEB)

    Remy, B.; Maillet, D.; Degiovanni, A. [Centre National de la Recherche Scientifique (CNRS), 54 - Vandoeuvre-les-Nancy (France)

    1996-12-31

    In the domain of thermal engineering, new materials have been developed which are characterized by a high thermal diffusivity (5 to 10 times greater than the best usual conductors: gold, copper, silicon..) but also by a small thickness (from few hundreds of microns to few microns). Their time of response is very short (some few milliseconds to some few microseconds) and they are mainly used as heat dissipating materials. The classical thermal diffusivity measurement techniques are unable to analyze the thermal properties of these materials. Therefore, a bench for fast thermal diffusivity measurements has been developed that uses a laser system for the excitation and for the measurement of temperature (infrared detector). In this study, the measurement bench is described and the metrological problems encountered are discussed. (J.S.) 10 refs.

  13. Tackling agricultural diffuse pollution: What might uptake of farmer-preferred measures deliver for emissions to water and air?

    Science.gov (United States)

    Collins, A L; Zhang, Y S; Winter, M; Inman, A; Jones, J I; Johnes, P J; Cleasby, W; Vrain, E; Lovett, A; Noble, L

    2016-03-15

    Mitigation of agricultural diffuse pollution poses a significant policy challenge across Europe and particularly in the UK. Existing combined regulatory and voluntary approaches applied in the UK continue to fail to deliver the necessary environmental outcomes for a variety of reasons including failure to achieve high adoption rates. It is therefore logical to identify specific on-farm mitigation measures towards which farmers express positive attitudes for higher future uptake rates. Accordingly, a farmer attitudinal survey was undertaken during phase one of the Demonstration Test Catchment programme in England to understand those measures towards which surveyed farmers are most receptive to increasing implementation in the future. A total of 29 on-farm measures were shortlisted by this baseline farm survey. This shortlist comprised many low cost or cost-neutral measures suggesting that costs continue to represent a principal selection criterion for many farmers. The 29 measures were mapped onto relevant major farm types and input, assuming 95% uptake, to a national scale multi-pollutant modelling framework to predict the technically feasible impact on annual agricultural emissions to water and air, relative to business as usual. Simulated median emission reductions, relative to current practise, for water management catchments across England and Wales, were estimated to be in the order sediment (20%)>ammonia (16%)>total phosphorus (15%) ≫ nitrate/methane (11%)>nitrous oxide (7%). The corresponding median annual total cost of the modelled scenario to farmers was £3 ha(-1)yr(-1), with a corresponding range of -£84 ha(-1)yr(-1) (i.e. a net saving) to £33 ha(-1)yr(-1). The results suggest that those mitigation measures which surveyed farmers are most inclined to implement in the future would improve the environmental performance of agriculture in England and Wales at minimum to low cost per hectare. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Measuring the diffusion of palliative care in long-term care facilities – a death census

    Directory of Open Access Journals (Sweden)

    Santos-Eggimann Brigitte

    2009-01-01

    Full Text Available Abstract Background The dissemination of palliative care for patients presenting complex chronic diseases at various stages has become an important matter of public health. A death census in Swiss long-term care facilities (LTC was set up with the aim of monitoring the frequency of selected indicators of palliative care. Methods The survey covered 150 LTC facilities (105 nursing homes and 45 home health services, each of which was asked to complete a questionnaire for every non-accidental death over a period of six months. The frequency of 4 selected indicators of palliative care (resort to a specialized palliative care service, the administration of opiates, use of any pain measurement scale or other symptom measurement scale was monitored in respect of the stages of care and analysed based on gender, age, medical condition and place of residence. Results Overall, 1200 deaths were reported, 29.1% of which were related to cancer. The frequencies of each indicator varied according to the type of LTC, mostly regarding the administration of opiate. It appeared that the access to palliative care remained associated with cancer, terminal care and partly with age, whereas gender and the presence of mental disorders had no effect on the indicators. In addition, the use of drugs was much more frequent than the other indicators. Conclusion The profile of patients with access to palliative care must become more diversified. Among other recommendations, equal access to opiates in nursing homes and in home health services, palliative care at an earlier stage and the systematic use of symptom management scales when resorting to opiates have to become of prime concern.

  15. Frequency-domain inverse Monte Carlo simulation for the diagnosis of the early cervical cancer based on NIR diffuse measurement

    Science.gov (United States)

    Zhao, Huijuan; Zhang, Shunqi; Wang, Zhaoxia; Miao, Hui; Du, Zhen; Jiang, Jingying

    2008-02-01

    This article aims at the optical parameter reconstruction technology for the frequency- domain measurement of near-infrared diffused light. For mimicking the cervix, a cylindrical model with hole in the middle is used in the simulation and experiments. Concerning the structure of the cervix, Monte-Carlo simulation is adopted for describing the photon migration in tissue and Perturbation Monte-Carlo is used for the reconstruction of the optical properties of cervix. The difficulties in the reconstruction of cervical optical properties with frequency domain measurement are the description of the tissue boundary, expression of the frequency-domain signal, and development of rapid reconstruction method for clinical use. To get the frequency domain signal in Monte Carlos simulation, discrete Fourier transformation of the photon migration history in time-domain is employed. By combining the perturbation Monte-Carlo simulation and the LM optimization technology, a rapid reconstruction algorithm is constructed, by which only one Monte-Carlo simulation is needed. The reconstruction method is validated by simulation and experiments on solid phantom. Simulation results show that the inaccuracy in reconstruction of absorption coefficient is less than 3% for a certain range of optical properties. The algorithm is also proved to be robust to the initial guess of optical properties and noise. Experimental results showed that the absorption coefficient can be reconstructed with inaccuracy of less than 10%. The absorption coefficient reconstruction for one set of measurement data can be fulfilled within one minute.

  16. Diffusion and Sedimentation Interaction Parameters for Measuring the Second Virial Coefficient and Their Utility as Predictors of Protein Aggregation

    Science.gov (United States)

    Saluja, Atul; Fesinmeyer, R. Matthew; Hogan, Sabine; Brems, David N.; Gokarn, Yatin R.

    2010-01-01

    The concentration-dependence of the diffusion and sedimentation coefficients (kD and ks, respectively) of a protein can be used to determine the second virial coefficient (B2), a parameter valuable in predicting protein-protein interactions. Accurate measurement of B2 under physiologically and pharmaceutically relevant conditions, however, requires independent measurement of kD and ks via orthogonal techniques. We demonstrate this by utilizing sedimentation velocity (SV) and dynamic light scattering (DLS) to analyze solutions of hen-egg white lysozyme (HEWL) and a monoclonal antibody (mAb1) in different salt solutions. The accuracy of the SV-DLS method was established by comparing measured and literature B2 values for HEWL. In contrast to the assumptions necessary for determining kD and ks via SV alone, kD and ks were of comparable magnitudes, and solution conditions were noted for both HEWL and mAb1 under which 1), kD and ks assumed opposite signs; and 2), kD ≥ ks. Further, we demonstrate the utility of kD and ks as qualitative predictors of protein aggregation through agitation and accelerated stability studies. Aggregation of mAb1 correlated well with B2, kD, and ks, thus establishing the potential for kD to serve as a high-throughput predictor of protein aggregation. PMID:20959107

  17. A Novel Method for Measuring the Diffusion, Partition and Convective Mass Transfer Coefficients of Formaldehyde and VOC in Building Materials

    Science.gov (United States)

    Xiong, Jianyin; Huang, Shaodan; Zhang, Yinping

    2012-01-01

    The diffusion coefficient (Dm) and material/air partition coefficient (K) are two key parameters characterizing the formaldehyde and volatile organic compounds (VOC) sorption behavior in building materials. By virtue of the sorption process in airtight chamber, this paper proposes a novel method to measure the two key parameters, as well as the convective mass transfer coefficient (hm). Compared to traditional methods, it has the following merits: (1) the K, Dm and hm can be simultaneously obtained, thus is convenient to use; (2) it is time-saving, just one sorption process in airtight chamber is required; (3) the determination of hm is based on the formaldehyde and VOC concentration data in the test chamber rather than the generally used empirical correlations obtained from the heat and mass transfer analogy, thus is more accurate and can be regarded as a significant improvement. The present method is applied to measure the three parameters by treating the experimental data in the literature, and good results are obtained, which validates the effectiveness of the method. Our new method also provides a potential pathway for measuring hm of semi-volatile organic compounds (SVOC) by using that of VOC. PMID:23145156

  18. Measurement of effective bulk and contact resistance of gas diffusion layer under inhomogeneous compression - Part II: Thermal conductivity

    Science.gov (United States)

    Roy Chowdhury, Prabudhya; Vikram, Ajit; Phillips, Ryan K.; Hoorfar, Mina

    2016-07-01

    The gas diffusion layer (GDL) is a thin porous layer sandwiched between a bipolar plate (BPP) and a catalyst coated membrane in a fuel cell. Besides providing passage for water and gas transport from and to the catalyst layer, it is responsible for electron and heat transfer from and to the BPP. In this paper, a method has been developed to measure the GDL bulk thermal conductivity and the contact resistance at the GDL/BPP interface under inhomogeneous compression occurring in an actual fuel cell assembly. Toray carbon paper GDL TGP-H-060 was tested under a range of compression pressure of 0.34 to 1.71 MPa. The results showed that the thermal contact resistance decreases non-linearly (from 3.8 × 10-4 to 1.17 × 10-4 Km2 W-1) with increasing pressure due to increase in microscopic contact area between the GDL and BPP; while the effective bulk thermal conductivity increases (from 0.56 to 1.42 Wm-1 K-1) with increasing the compression pressure. The thermal contact resistance was found to be greater (by a factor of 1.6-2.8) than the effective bulk thermal resistance for all compression pressure ranges applied here. This measurement technique can be used to identify optimum GDL based on minimum bulk and contact resistances measured under inhomogeneous compression.

  19. Comparison of ultraviolet Bi-directional Reflectance Distribution Function (BRDF) measurements of diffusers used in the calibration of the Total Ozone Mapping Spectrometer (TOMS)

    NARCIS (Netherlands)

    Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.

    2002-01-01

    The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those

  20. Determination of diffusion coefficients of carbon dioxide in water between 268 and 473 K in a high-pressure capillary optical cell with in situ Raman spectroscopic measurements

    Science.gov (United States)

    Lu, Wanjun; Guo, Huirong; Chou, I.-Ming; Burruss, R.C.; Li, Lanlan

    2013-01-01

    Accurate values of diffusion coefficients for carbon dioxide in water and brine at reservoir conditions are essential to our understanding of transport behavior of carbon dioxide in subsurface pore space. However, the experimental data are limited to conditions at low temperatures and pressures. In this study, diffusive transfer of carbon dioxide in water at pressures up to 45 MPa and temperatures from 268 to 473 K was observed within an optical capillary cell via time-dependent Raman spectroscopy. Diffusion coefficients were estimated by the least-squares method for the measured variations in carbon dioxide concentration in the cell at various sample positions and time. At the constant pressure of 20 MPa, the measured diffusion coefficients of carbon dioxide in water increase with increasing temperature from 268 to 473 K. The relationship between diffusion coefficient of carbon dioxide in water [D(CO2) in m2/s] and temperature (T in K) was derived with Speedy–Angell power-law approach as: D(CO2)=D0[T/Ts-1]m where D0 = 13.942 × 10−9 m2/s, Ts = 227.0 K, and m = 1.7094. At constant temperature, diffusion coefficients of carbon dioxide in water decrease with pressure increase. However, this pressure effect is rather small (within a few percent).

  1. Improved differentiation between hepatic hemangioma and metastases on diffusion-weighted MRI by measurement of standard deviation of apparent diffusion coefficient.

    Science.gov (United States)

    Hardie, Andrew D; Egbert, Robert E; Rissing, Michael S

    2015-01-01

    Diffusion-weighted magnetic resonance imaging (DW-MR) can be useful in the differentiation of hemangiomata from liver metastasis, but improved methods other than by mean apparent diffusion coefficient (mADC) are needed. A retrospective review identified 109 metastatic liver lesions and 86 hemangiomata in 128 patients who had undergone DW-MR. For each lesion, mADC and the standard deviation of the mean ADC (sdADC) were recorded and compared by receiver operating characteristic analysis. Mean mADC was higher in benign hemangiomata (1.52±0.12 mm(2)/s) than in liver metastases (1.33±0.18 mm(2)/s), but there was significant overlap in values. The mean sdADC was lower in hemangiomata (101±17 mm(2)/s) than metastases (245±25 mm(2)/s) and demonstrated no overlap in values, which was significantly different (P<.0001). Hemangiomata may be better able to be differentiated from liver metastases on the basis of sdADC than by mADC, although further studies are needed. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Influence of wind-speed on short-duration NO2 measurements using Palmes and Ogawa passive diffusion samplers

    Science.gov (United States)

    Masey, Nicola; Gillespie, Jonathan; Heal, Mathew R.; Hamilton, Scott; Beverland, Iain J.

    2017-07-01

    We assessed the precision and accuracy of nitrogen dioxide (NO2) concentrations over 2-day, 3-day and 7-day exposure periods measured with the following types of passive diffusion samplers: standard (open) Palmes tubes; standard Ogawa samplers with commercially-prepared Ogawa absorbent pads (Ogawa[S]); and modified Ogawa samplers with absorbent-impregnated stainless steel meshes normally used in Palmes tubes (Ogawa[P]). We deployed these passive samplers close to the inlet of a chemiluminescence NO2 analyser at an urban background site in Glasgow, UK over 32 discrete measurement periods. Duplicate relative standard deviation was personal exposure monitoring, are likely to benefit from protection of these sampling devices from the effects of wind, for example by use of a mesh or membrane across the open end. The uptake rate of Ogawa[P] samplers was not associated with wind-speed resulting in a high correlation between estimated concentrations and observed analyser concentrations. The use of Palmes meshes in Ogawa[P] samplers reduced the cost of sampler preparation and removed uncertainty associated with the unknown manufacturing process for the commercially-prepared collection pads.

  3. Continuous measurement of soil carbon efflux with Forced Diffusion (FD) chambers in a tundra ecosystem of Alaska.

    Science.gov (United States)

    Kim, Yongwon; Park, Sang-Jong; Lee, Bang-Yong; Risk, David

    2016-10-01

    Soil is a significant source of CO2 emission to the atmosphere, and this process is accelerating at high latitudes due to rapidly changing climates. To investigate the sensitivity of soil CO2 emissions to high temporal frequency variations in climate, we performed continuous monitoring of soil CO2 efflux using Forced Diffusion (FD) chambers at half-hour intervals, across three representative Alaskan soil cover types with underlying permafrost. These sites were established during the growing season of 2015, on the Seward Peninsula of western Alaska. Our chamber system is conceptually similar to a dynamic chamber, though FD is more durable and water-resistant and consumes less power, lending itself to remote deployments. We first conducted methodological tests, testing different frequencies of measurement, and did not observe a significant difference between collecting data at 30-min and 10-min measurement intervals (averaged half-hourly) (pFD chamber networks would be an effective means for quantifying growing and non-growing season soil carbon budgets, with optimal pairing with time-lapse imagery for tracking local and regional changes in environment and climate in a warming Arctic. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  4. An automatic measuring system for mapping of spectral and angular dependence of direct and diffuse solar radiation; Et automatisk maalesystem for kartlegging av vinkel- og spektralfordeling av direkte og diffus solstraaling

    Energy Technology Data Exchange (ETDEWEB)

    Grandum, Oddbjoern

    1997-12-31

    In optimizing solar systems, it is necessary to know the spectral and angular dependence of the radiation. The general nonlinear character of most solar energy systems accentuates this. This thesis describes a spectroradiometer that will measure both the direct component of the solar radiation and the angular dependence of the diffuse component. Radiation from a selected part of the sky is transported through a movable set of tube sections on to a stationary set of three monochromators with detectors. The beam transport system may effectively be looked upon as a single long tube aimed at a particular spot in the sky. The half value of the effective opening angle is 1.3{sup o} for diffuse radiation and 2.8{sup o} for direct radiation. The whole measurement process is controlled and operated by a PC and normally runs without manual attention. The instrument is built into a caravan. The thesis describes in detail the experimental apparatus, calibration and measurement accuracies. To map the diffuse radiation, one divides the sky into 26 sectors of equal solid angle. A complete measurement cycle is then made at a random point within each sector. These measurements are modelled by fitting to spherical harmonics, enforcing symmetry around the solar direction and the horizontal plane. The direct radiation is measured separately. Also the circumsolar sector is given special treatment. The measurements are routinely checked against global radiation measured in parallel by a standard pyranometer, and direct solar radiation by a pyrheliometer. An extensive improvement programme is being planned for the instrument, including the use of a photomultiplier tube to measure the UV part of the spectrum, a diode array for the 400-1100 nm range, and use of a Ge diode for the 1000-1900 nm range. 78 refs., 90 figs., 31 tabs.

  5. "Diffusive Gradients in Thin Films" Techniques Provide Representative Time-Weighted Average Measurements of Inorganic Nutrients in Dynamic Freshwater Systems.

    Science.gov (United States)

    Huang, Jianyin; Bennett, William W; Welsh, David T; Li, Tianling; Teasdale, Peter R

    2016-12-20

    Nutrient concentrations in freshwater are highly variable over time, with changes driven by weather events, anthropogenic sources, modifications to catchment hydrology or habitats, and internal biogeochemical processes. Measuring infrequently collected grab samples is unlikely to adequately represent nutrient concentrations in such dynamic systems. In contrast, in situ passive sampling techniques, such as the "diffusive gradients in thin films" (DGT) technique, provide time-weighted average analyte concentrations over the entire deployment time. A pair of recently developed DGT techniques for nitrate (A520E-DGT) and ammonium (PrCH-DGT), as well as the Metsorb-DGT technique for phosphate, were used to monitor inorganic nutrients in different freshwater systems (i.e., streams and wetlands) with a range of environmental values and that were affected by different catchment types. Measurements of grab samples collected frequently (1-2 times daily, 8-10 a.m. and 2-4 p.m.) showed that concentrations of NH4-N and NO3-N changed dramatically in most of the studied freshwater systems over short time scales, while there were only relatively small fluctuations in PO4-P. The DGT measurements were highly representative in comparison with the average nutrient concentrations obtained from daily grab samples over short-term (24 h) and long-term (72 h) deployments. The ratios of DGT-labile concentrations to the average concentrations from grab samples were between 1.00 and 1.12 over the studied deployment periods. The results of this study confirmed that DGT measurements provided a reliable and robust method for monitoring NH4-N, NO3-N, and PO4-P in a diverse range of dynamic freshwater systems.

  6. A tensor model and measures of microscopic anisotropy for double-wave-vector diffusion-weighting experiments with long mixing times.

    Science.gov (United States)

    Lawrenz, Marco; Koch, Martin A; Finsterbusch, Jürgen

    2010-01-01

    Experiments with two diffusion-weighting periods applied successively in a single experiment, so-called double-wave-vector (DWV) diffusion-weighting experiments, are a promising tool for the investigation of material or tissue structure on a microscopic level, e.g. to determine cell or compartment sizes or to detect pore or cell anisotropy. However, the theoretical descriptions presented so far for experiments that aim to investigate the microscopic anisotropy with a long mixing time between the two diffusion weightings, are limited to certain wave vector orientations, specific pore shapes, and macroscopically isotropic samples. Here, the signal equations for fully restricted diffusion are re-investigated in more detail. A general description of the signal behavior for arbitrary wave vector directions, pore or cell shapes, and orientation distributions of the pores or cells is obtained that involves a fourth-order tensor approach. From these equations, a rotationally invariant measure of the microscopic anisotropy, termed MA, is derived that yields information complementary to that of the (macroscopic) anisotropy measures of standard diffusion-tensor acquisitions. Furthermore, the detailed angular modulation for arbitrary cell shapes with an isotropic orientation distribution is derived. Numerical simulations of the MR signal with a Monte-Carlo algorithms confirm the theoretical considerations. The extended theoretical description and the introduction of a reliable measure of the microscopic anisotropy may help to improve the applicability and reliability of corresponding experiments. Copyright 2009 Elsevier Inc. All rights reserved.

  7. Diffusion model for iontophoresis measured by laser-Doppler perfusion flowmetry, applied to normal and preeclamptic pregnancies

    NARCIS (Netherlands)

    de Mul, Frits F. M.; Blaauw, Judith; Smit, Andries J.; Rakhorst, Gerhard

    2007-01-01

    We present a physical model to describe iontophoresis time recordings. The model is a combination of monodimensional material diffusion and decay, probably due to transport by blood flow. It has four adjustable parameters, the diffusion coefficient, the decay constant, the height of the response,

  8. Adenosine triphosphate diffusion through poly(ethylene glycol) diacrylate hydrogels can be tuned by cross-link density as measured by PFG-NMR

    Science.gov (United States)

    Majer, Günter; Southan, Alexander

    2017-06-01

    The diffusion of small molecules through hydrogels is of great importance for many applications. Especially in biological contexts, the diffusion of nutrients through hydrogel networks defines whether cells can survive inside the hydrogel or not. In this contribution, hydrogels based on poly(ethylene glycol) diacrylate with mesh sizes ranging from ξ = 1.1 to 12.9 nm are prepared using polymers with number-average molecular weights between Mn = 700 and 8000 g/mol. Precise measurements of diffusion coefficients D of adenosine triphosphate (ATP), an important energy carrier in biological systems, in these hydrogels are performed by pulsed field gradient nuclear magnetic resonance. Depending on the mesh size, ξ, and on the polymer volume fraction of the hydrogel after swelling, ϕ, it is possible to tune the relative ATP diffusion coefficient D/D0 in the hydrogels to values between 0.14 and 0.77 compared to the ATP diffusion coefficient D0 in water. The diffusion coefficients of ATP in these hydrogels are compared with predictions of various mathematical expressions developed under different model assumptions. The experimental data are found to be in good agreement with the predictions of a modified obstruction model or the free volume theory in combination with the sieving behavior of the polymer chains. No reasonable agreement was found with the pure hydrodynamic model.

  9. Miniaturisation of Pressure-Sensitive Paint Measurement Systems Using Low-Cost, Miniaturised Machine Vision Cameras

    Directory of Open Access Journals (Sweden)

    Mark Kenneth Quinn

    2017-07-01

    Full Text Available Measurements of pressure-sensitive paint (PSP have been performed using new or non-scientific imaging technology based on machine vision tools. Machine vision camera systems are typically used for automated inspection or process monitoring. Such devices offer the benefits of lower cost and reduced size compared with typically scientific-grade cameras; however, their optical qualities and suitability have yet to be determined. This research intends to show relevant imaging characteristics and also show the applicability of such imaging technology for PSP. Details of camera performance are benchmarked and compared to standard scientific imaging equipment and subsequent PSP tests are conducted using a static calibration chamber. The findings demonstrate that machine vision technology can be used for PSP measurements, opening up the possibility of performing measurements on-board small-scale model such as those used for wind tunnel testing or measurements in confined spaces with limited optical access.

  10. Miniaturisation of Pressure-Sensitive Paint Measurement Systems Using Low-Cost, Miniaturised Machine Vision Cameras.

    Science.gov (United States)

    Quinn, Mark Kenneth; Spinosa, Emanuele; Roberts, David A

    2017-07-25

    Measurements of pressure-sensitive paint (PSP) have been performed using new or non-scientific imaging technology based on machine vision tools. Machine vision camera systems are typically used for automated inspection or process monitoring. Such devices offer the benefits of lower cost and reduced size compared with typically scientific-grade cameras; however, their optical qualities and suitability have yet to be determined. This research intends to show relevant imaging characteristics and also show the applicability of such imaging technology for PSP. Details of camera performance are benchmarked and compared to standard scientific imaging equipment and subsequent PSP tests are conducted using a static calibration chamber. The findings demonstrate that machine vision technology can be used for PSP measurements, opening up the possibility of performing measurements on-board small-scale model such as those used for wind tunnel testing or measurements in confined spaces with limited optical access.

  11. In situ measurements of thermal diffusivity in sediments of the methane-rich zone of Cascadia Margin, NE Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Kira Homola

    2015-02-01

    Full Text Available Abstract Thermal diffusivity (TD is a measure of the temperature response of a material to external thermal forcing. In this study, TD values for marine sediments were determined in situ at two locations on the Cascadia Margin using an instrumented sediment probe deployed by a remotely operated vehicle. TD measurements in this area of the NE Pacific Ocean are important for characterizing the upslope edge of the methane hydrate stability zone, which is the climate-sensitive boundary of a global-scale carbon reservoir. The probe was deployed on the Cascadia Margin at water depths of 552 and 1049 m for a total of 6 days at each site. The instrumented probe consisted of four thermistors aligned vertically, one sensor exposed to the bottom water and one each at 5, 10, and 15 cm within the sediment. Results from each deployment were analyzed using a thermal conduction model applying a range of TD values to obtain the best fit with the experimental data. TD values corresponding to the lowest standard deviations from the numerical model runs were selected as the best approximations. Overall TDs of Cascadia Margin sediments of 4.33 and 1.15 × 10–7 m2 s–1 were calculated for the two deployments. These values, the first of their kind to be determined from in situ measurements on a methane hydrate-rich continental margin, are expected to be useful in the development of models of bottom-water temperature increases and their implications on a global scale.

  12. Simultaneous retrieval of aerosol and surface optical properties from combined airborne- and ground-based direct and diffuse radiometric measurements

    Directory of Open Access Journals (Sweden)

    C. K. Gatebe

    2010-03-01

    Full Text Available This paper presents a new method for simultaneously retrieving aerosol and surface reflectance properties from combined airborne and ground-based direct and diffuse radiometric measurements. The method is based on the standard Aerosol Robotic Network (AERONET method for retrieving aerosol size distribution, complex index of refraction, and single scattering albedo, but modified to retrieve aerosol properties in two layers, below and above the aircraft, and parameters on surface optical properties from combined datasets (Cloud Absorption Radiometer (CAR and AERONET data. A key advantage of this method is the inversion of all available spectral and angular data at the same time, while accounting for the influence of noise in the inversion procedure using statistical optimization. The wide spectral (0.34–2.30 μm and angular range (180° of the CAR instrument, combined with observations from an AERONET sunphotometer, provide sufficient measurement constraints for characterizing aerosol and surface properties with minimal assumptions. The robustness of the method was tested on observations made during four different field campaigns: (a the Southern African Regional Science Initiative 2000 over Mongu, Zambia, (b the Intercontinental Transport Experiment-Phase B over Mexico City, Mexico (c Cloud and Land Surface Interaction Campaign over the Atmospheric Radiation Measurement (ARM Central Facility, Oklahoma, USA, and (d the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS over Elson Lagoon in Barrow, Alaska, USA. The four areas are dominated by different surface characteristics and aerosol types, and therefore provide good test cases for the new inversion method.

  13. Evaluation of Diffuse Reflection Infrared Spectrometry for End-of-Shift Measurement of α-quartz in Coal Dust Samples.

    Science.gov (United States)

    Miller, Arthur L; Murphy, Nathaniel C; Bayman, Sean J; Briggs, Zachary P; Kilpatrick, Andrew D; Quinn, Courtney A; Wadas, Mackenzie R; Cauda, Emanuele G; Griffiths, Peter R

    2015-01-01

    The inhalation of toxic substances is a major threat to the health of miners, and dust containing respirable crystalline silica (α-quartz) is of particular concern, due to the recent rise in cases of coal workers' pneumoconiosis and silicosis in some U.S. mining regions. Currently, there is no field-portable instrument that can measure airborne α-quartz and give miners timely feedback on their exposure. The U.S. National Institute for Occupational Safety and Health (NIOSH) is therefore conducting studies to investigate technologies capable of end-of-shift or real-time measurement of airborne quartz. The present study focuses on the potential application of Fourier transform infrared (FT-IR) spectrometry conducted in the diffuse reflection (DR) mode as a technique for measuring α-quartz in respirable mine dust. A DR accessory was used to analyze lab-generated respirable samples of Min-U-Sil 5 (which contains more than 90% α-quartz) and coal dust, at mass loadings in the ranges of 100-600 μg and 600-5300 μg, respectively. The dust samples were deposited onto three different types of filters, borosilicate fiberglass, nylon, and polyvinyl chloride (PVC). The reflectance, R, was calculated by the ratio of a blank filter and a filter with deposited mine dust. Results suggest that for coal and pure quartz dusts deposited on 37 mm PVC filters, measurements of -log R correlate linearly with known amounts of quartz on filters, with R(2) values of approximately 0.99 and 0.94, respectively, for samples loaded up to ∼4000 μg. Additional tests were conducted to measure quartz in coal dusts deposited onto the borosilicate fiberglass and nylon filter media used in the NIOSH-developed Personal Dust Monitor (PDM). The nylon filter was shown to be amenable to DR analysis, but quantification of quartz is more accurate when the filter is "free," as opposed to being mounted in the PDM filter holder. The borosilicate fiberglass filters were shown to produce excessive

  14. Soil Greenhouse Gas Flux Measurements with Automated and Manual Static Chambers, Forced Diffusion Chamber, and Concentration Profiles

    Science.gov (United States)

    Ruan, L.; Oikawa, P. Y.; Géli, M.; Verfaillie, J. G.; Sturtevant, C. S.; Knox, S. H.; Nickerson, N.; McArthur, G.; Creelman, C.; Saad, N.; Alstad, K. P.; Arata, C.; Baldocchi, D. D.; Silver, W. L.

    2014-12-01

    Accurate measurements of soil greenhouse gas fluxes are critical for determining the role of ecosystem dynamics, both natural and managed, in climate change. We compared concentration profile methods with static, forced diffusion, and automated flux chambers using a combination of infrared gas analyzers (IRGA), gas chromatography, and cavity ring-down laser absorption spectroscopy (Picarro G2508) during field campaigns in managed ecosystems in California. At a drained peatland pasture site, we observed large differences between methods (fluxes ranged between 2-15 μmol CO2 m-2 s-1). However, low temporal/high spatial replication measurements (manual LI6400 chamber measurements; n=6 collars) encompassed the full range of CO2 fluxes observed across all other methods. This suggests that the majority of variability in CO2 emissions was due to high spatial variation in soil respiration and not due to methodological differences across measurement systems. At a dry upland pasture site, water, nitrate solution and manure were applied during the experimental period to expand the range of greenhouse fluxes. Preliminary results showed good agreement of gas fluxes between static and automatic chamber sampling. We observed large CO2 and N2O fluxes after manure application with both methods. The two chamber types were highly significantly correlated for N2O (slope=0.74, r2=0.94). Mean CH4 fluxes measured by static chambers was -0.36 μg cm-2 h-1, similar to the -0.57 μg cm-2 h-1 measured by the automatic chamber and Picarro analyzer during the study period. Overall, our results suggest that both automated and static chamber methods are in good agreement, but automated chambers are advantageous for capturing diel dynamics and pulse responses to experimental treatments. Our results also highlight the importance of spatial replication, which can be difficult to achieve using expensive automated chambers. We suggest future research efforts to seek a combination of high spatially

  15. A protein chimera including PspA in fusion with PotD is protective against invasive pneumococcal infection and reduces nasopharyngeal colonization in mice.

    Science.gov (United States)

    Converso, T R; Goulart, C; Darrieux, M; Leite, L C C

    2017-09-12

    Despite the success of the available polysaccharide-based vaccines against Streptococcus pneumoniae in preventing invasive diseases, this bacterium remains a major cause of death in many parts of the world. New vaccine strategies are needed in order to increase protection. Thus, the utilization of fusion proteins is being investigated as an alternative to the current formulations. In the present work, we demonstrate that a chimeric protein, composed of PspA and PotD in fusion is able to maintain the protective characteristics of both parental proteins, providing protection against systemic infection while reducing nasal colonization. The hybrid was not able to improve the response against invasive disease elicited by PspA alone, but the inclusion of PotD was able to reduce colonization, an effect never observed using subcutaneous immunization with PspA. The mechanisms underlying the protective efficacy of the rPspA-PotD hybrid protein were investigated, revealing the production of antibodies with an increased binding capacity to pneumococcal strains of diverse serotypes and genetic backgrounds, enhanced opsonophagocytosis, and secretion of IL-17 by splenocytes. These findings reinforce the use of chimeric proteins based on surface antigens as an effective strategy against pneumococcal infections. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The putative thiosulfate sulfurtransferases PspE and GlpE contribute to virulence of Salmonella Typhimurium in the mouse model of systemic disease

    DEFF Research Database (Denmark)

    Wallrodt, Inke; Jelsbak, Lotte; Thorndahl, Lotte

    2013-01-01

    The phage-shock protein PspE and GlpE of the glycerol 3-phosphate regulon of Salmonella enterica serovar Typhimurium are predicted to belong to the class of thiosulfate sulfurtransferases, enzymes that traffic sulfur between molecules. In the present study we demonstrated that the two genes contr...

  17. Diffusion and molecular interactions in a methanol/polyimide system probed by coupling time-resolved FTIR spectroscopy with gravimetric measurements.

    Science.gov (United States)

    Musto, Pellegrino; Galizia, Michele; La Manna, Pietro; Pannico, Marianna; Mensitieri, Giuseppe

    2014-01-01

    In this contribution the diffusion of methanol in a commercial polyimide (PMDA-ODA) is studied by coupling gravimetric measurements with in-situ, time-resolved FTIR spectroscopy. The spectroscopic data have been treated with two complementary techniques, i.e., difference spectroscopy (DS) and least-squares curve fitting (LSCF). These approaches provided information about the overall diffusivity, the nature of the molecular interactions among the system components and the dynamics of the various molecular species. Additional spectroscopic measurements on thin film samples (about 2 μm) allowed us to identify the interaction site on the polymer backbone and to propose likely structures for the H-bonding aggregates. Molar absorptivity values from a previous literature report allowed us to estimate the population of first-shell and second-shell layers of methanol in the polymer matrix. In terms of diffusion kinetics, the gravimetric and spectroscopic estimates of the diffusion coefficients were found to be in good agreement with each other and with previous literature reports. A Fickian behavior was observed throughout, with diffusivity values markedly affected by the total concentration of sorbed methanol.

  18. Visible near infrared diffuse reflectance spectroscopy (VisNIR DRS) for rapid measurement of organic matter in compost.

    Science.gov (United States)

    McWhirt, Amanda L; Weindorf, David C; Chakraborty, Somsubhra; Li, Bin

    2012-10-01

    Commercial compost is the inherently variable organic product of a controlled decomposition process. In the USA, assessment of compost's physicochemical parameters presently relies on standard laboratory analyses set forth in Test Methods for the Examination of Composting and Compost (TMECC). A rapid, field-portable means of assessing the organic matter (OM) content of compost products would be useful to help producers ensure optimal uniformity in their compost products. Visible near infrared diffuse reflectance spectroscopy (VisNIR DRS) is a rapid, proximal-sensing technology proven effective at quantifying organic matter levels in soils. As such, VisNIR DRS was evaluated to assess its applicability to compost. Thirty-six compost samples representing a wide variety of source materials and moisture content were collected and scanned with VisNIR DRS under moist and oven-dry conditions. Partial least squares (PLS) regression and principal component regression (PCR) were used to relate the VisNIR DRS spectra with laboratory-measured OM to build compost OM prediction models. Raw reflectance, and first- and second-derivatives of the reflectance spectra were considered. In general, PLS regression outperformed PCR and the oven-dried first-derivative PLS model produced an r(2) value of 0.82 along with a residual prediction deviation value of 1.72. As such, VisNIR DRS shows promise as a suitable technique for the analysis of compost OM content for dried samples.

  19. Transport properties investigation of aqueous protic ionic liquid solutions through conductivity, viscosity, and NMR self-diffusion measurements.

    Science.gov (United States)

    Anouti, Mérièm; Jacquemin, Johan; Porion, Patrice

    2012-04-12

    We present a study on the transport properties through conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids--pyrrolidinium hydrogen sulfate, [Pyrr][HSO(4)], and pyrrolidinium trifluoroacetate, [Pyrr][CF(3)COO]--and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then investigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other words, for such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content, the labile protons are in solution as H(3)O(+). This water weight fraction appears to be the solvation limit of the H(+) ions by water molecules in these two PILs solutions. However, [Pyrr][HSO(4)] and [Pyrr][CF(3)COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF(3)COO], η, σ, D, and the attractive potential, E(pot), between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO(4)], the strong H-bond between the HSO(4)(-) anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS·cm(-1) for water weight fraction close to 60% at 298 K.

  20. Development and Application of a Two-Tier Diagnostic Test Measuring College Biology Students' Understanding of Diffusion and Osmosis after a Course of Instruction.

    Science.gov (United States)

    Odom, Arthur Louis; Barrow, Lloyd H.

    1995-01-01

    Presents a diagnostic test for measuring college biology students' understanding of diffusion. Three general steps were used: (1) defining the content boundaries; (2) collecting information on students' misconceptions; and (3) instrument development. The split half reliability was 0.74, difficulty indices ranged from 0.23 to 0.95, and the…

  1. Theoretical reconsiderations when estimating the mesophyll conductance to CO2 diffusion in leaves of C3 plants by analysis of combined gas exchange and chlorophyll fluorescence measurements

    NARCIS (Netherlands)

    Yin, X.; Struik, P.C.

    2009-01-01

    Existing methods to estimate the mesophyll conductance to CO2 diffusion (gm) are often based on combined gas exchange and chlorophyll fluorescence measurements. However, estimations of average gm by these methods are often unreliable either because the range of usable data is too narrow or because

  2. Diffusion of lipids and GPI-anchored proteins in actin-free plasma membrane vesicles measured by STED-FCS

    DEFF Research Database (Denmark)

    Schneider, Falk; Waithe, Dominic; Clausen, Mathias P

    2017-01-01

    Diffusion and interaction dynamics of molecules at the plasma membrane play an important role in cellular signalling, and they are suggested to be strongly associated with the actin cytoskeleton. Here, we utilise super-resolution STED microscopy combined with fluorescence correlation spectroscopy...... (STED-FCS) to access and compare the diffusion characteristics of fluorescent lipid analogues and GPI-anchored proteins (GPI-APs) in the live cell plasma membrane and in actin cytoskeleton-free cell-derived giant plasma membrane vesicles (GPMVs). Hindered diffusion of phospholipids and sphingolipids...... forming immobile clusters, both of which disappear in GPMVs. Our data underline the crucial role of the actin cortex in maintaining hindered diffusion modes of many but not all of the membrane molecules, and highlight a powerful experimental approach to decipher specific influences on molecular plasma...

  3. Solutions Network Formulation Report. Aerosol Polarimetry Sensor Measurements of Diffuse-to-Global Irradiance Ratio for Improved Forecasting of Plant Productivity and Health

    Science.gov (United States)

    Knowlton, Kelly; Andrews, Jane C.; Ryan, Robert E.

    2007-01-01

    Studies have shown that vegetation is directly sensitive to changes in the diffuse-to-global irradiance ratio and that increased percentage of diffuse irradiation can accelerate photosynthesis. Therefore, measurements of diffuse versus global irradiance could be useful for monitoring crop productivity and overall vegetative health as they relate to the total amount of particulates in the air that result from natural disasters or anthropogenic (manmade) causes. While the components of solar irradiance are measured by satellite and surface sensors and calculated with atmospheric models, disagreement exists between the results, creating a need for more accurate and comprehensive retrievals of atmospheric aerosol parameters. Two satellite sensors--APS and VIIRS--show promise for retrieving aerosol properties at an unprecedented level of accuracy. APS is expected to be launched in December 2008. The planned launch date for VIIRS onboard NPP is September 2009. Identified partners include the USDA s ARS, North Carolina State University, Purdue Climate Change Research Center, and the Cooperative Institute for Research in the Atmosphere at Colorado State University. Although at present no formal DSSs (decision support systems) require accurate values of diffuse-to-global irradiance, this parameter is sufficiently important that models are being developed that will incorporate these measurements. This candidate solution is aligned with the Agricultural Efficiency and Air Quality National Applications.

  4. Effect of modulation frequency bandwidth on measurement accuracy and precision for digital diffuse optical spectroscopy (dDOS)

    Science.gov (United States)

    Jung, Justin; Istfan, Raeef; Roblyer, Darren

    2014-03-01

    Near-infrared (NIR) frequency-domain Diffuse Optical Spectroscopy (DOS) is an emerging technology with a growing number of potential clinical applications. In an effort to reduce DOS system complexity and improve portability, we recently demonstrated a direct digital sampling method that utilizes digital signal generation and detection as a replacement for more traditional analog methods. In our technique, a fast analog-to-digital converter (ADC) samples the detected time-domain radio frequency (RF) waveforms at each modulation frequency in a broad-bandwidth sweep (50- 300MHz). While we have shown this method provides comparable results to other DOS technologies, the process is data intensive as digital samples must be stored and processed for each modulation frequency and wavelength. We explore here the effect of reducing the modulation frequency bandwidth on the accuracy and precision of extracted optical properties. To accomplish this, the performance of the digital DOS (dDOS) system was compared to a gold standard network analyzer based DOS system. With a starting frequency of 50MHz, the input signal of the dDOS system was swept to 100, 150, 250, or 300MHz in 4MHz increments and results were compared to full 50-300MHz networkanalyzer DOS measurements. The average errors in extracted μa and μs' with dDOS were lowest for the full 50-300MHz sweep (less than 3%) and were within 3.8% for frequency bandwidths as narrow as 50-150MHz. The errors increased to as much as 9.0% when a bandwidth of 50-100MHz was tested. These results demonstrate the possibility for reduced data collection with dDOS without critical compensation of optical property extraction.

  5. Effect of Lung Inflation Level on Hyperpolarized 3He Apparent Diffusion Coefficient Measurements in Never-Smokers

    Science.gov (United States)

    Halaweish, Ahmed F.; Thedens, Daniel R.; Fuld, Matthew K.; Sieren, Jered P.; van Beek, Edwin J. R.

    2013-01-01

    Purpose: To evaluate the effects of lung volume differences on apparent diffusion coefficient (ADC) measurements on a regional basis, with breath holds at volumes adjusted for differences in lung size across individuals according to the subject’s vital capacity (VC). Materials and Methods: This study was approved by the local institutional review board and was compliant with HIPAA. Informed consent was obtained from all subjects. Imaging was performed under a physician’s Investigational New Drug application from the Food and Drug Administration. ADC changes as a function of inflation levels were evaluated in 24 healthy never-smokers across three lung volumes (20%, 60%, and 100% VC) on the basis of the spirometric data collected from each subject. Response variables based on lung volume and anatomic position were assessed with multifactorial analysis of variance followed by posthoc pair-wise testing. Imaging was performed with a 1.5-T magnetic resonance (MR) unit with use of a two-dimensional gradient-echo fast low-angle shot sequence. Results: Significant differences in ADCs between lung volumes were observed for all inflation levels (20%, 60%, and 100% VC; P lung only). In addition, significant differences between mean values in the left and right lungs with respect to those in the whole lung were observed at the lower lung inflation levels (20% and 60% VC, P lung volume changes, emphasizing the need for tight control over lung volume when performing hyperpolarized helium 3 (3He) lung studies if 3He MR imaging is to be used to follow up small longitudinal changes in lung abnormalities. © RSNA, 2013 PMID:23592768

  6. Li diffusion in zircon

    Science.gov (United States)

    Cherniak, D. J.; Watson, E. B.

    2010-09-01

    Diffusion of Li under anhydrous conditions at 1 atm and under fluid-present elevated pressure (1.0-1.2 GPa) conditions has been measured in natural zircon. The source of diffusant for 1-atm experiments was ground natural spodumene, which was sealed under vacuum in silica glass capsules with polished slabs of zircon. An experiment using a Dy-bearing source was also conducted to evaluate possible rate-limiting effects on Li diffusion of slow-diffusing REE+3 that might provide charge balance. Diffusion experiments performed in the presence of H2O-CO2 fluid were run in a piston-cylinder apparatus, using a source consisting of a powdered mixture of spodumene, quartz and zircon with oxalic acid added to produce H2O-CO2 fluid. Nuclear reaction analysis (NRA) with the resonant nuclear reaction 7Li(p,γ)8Be was used to measure diffusion profiles for the experiments. The following Arrhenius parameters were obtained for Li diffusion normal to the c-axis over the temperature range 703-1.151°C at 1 atm for experiments run with the spodumene source: D_{text{Li}} = 7.17 × 10^{ - 7} { exp }( - 275 ± 11 {text{kJmol}}^{ - 1} /{text{RT}}){text{m}}2 {text{s}}^{ - 1}. Diffusivities are similar for transport parallel to the c-axis, indicating little anisotropy for Li diffusion in zircon. Similar Li diffusivities were also found for experiments run under fluid-present conditions and for the experiment run with the Dy-bearing source. Li diffusion is considerably faster than diffusion of other cations in zircon, with a smaller activation energy for diffusion. Although Li diffusion in zircon is comparatively rapid, zircons will be moderately retentive of Li signatures at mid-crustal metamorphic temperatures, but they are unlikely to retain this information for geologically significant times under high-grade metamorphism.

  7. Cortical thickness, surface area and volume measures in Parkinson's disease, multiple system atrophy and progressive supranuclear palsy.

    Directory of Open Access Journals (Sweden)

    Amanda Worker

    Full Text Available Parkinson's disease (PD, Multiple System Atrophy (MSA and Progressive Supranuclear Palsy (PSP are neurodegenerative diseases that can be difficult to distinguish clinically. The objective of the current study was to use surface-based analysis techniques to assess cortical thickness, surface area and grey matter volume to identify unique morphological patterns of cortical atrophy in PD, MSA and PSP and to relate these patterns of change to disease duration and clinical features.High resolution 3D T1-weighted MRI volumes were acquired from 14 PD patients, 18 MSA, 14 PSP and 19 healthy control participants. Cortical thickness, surface area and volume analyses were carried out using the automated surface-based analysis package FreeSurfer (version 5.1.0. Measures of disease severity and duration were assessed for correlation with cortical morphometric changes in each clinical group.Results show that in PSP, widespread cortical thinning and volume loss occurs within the frontal lobe, particularly the superior frontal gyrus. In addition, PSP patients also displayed increased surface area in the pericalcarine. In comparison, PD and MSA did not display significant changes in cortical morphology.These results demonstrate that patients with clinically established PSP exhibit distinct patterns of cortical atrophy, particularly affecting the frontal lobe. These results could be used in the future to develop a useful clinical application of MRI to distinguish PSP patients from PD and MSA patients.

  8. Easy measurement of diffusion coefficients of EGFP-tagged plasma membrane proteins using k-space Image Correlation Spectroscopy

    DEFF Research Database (Denmark)

    Christensen, Eva Arnspang; Koffman, Jennifer Skaarup; Marlar, Saw

    2014-01-01

    Lateral diffusion and compartmentalization of plasma membrane proteins are tightly regulated in cells and thus, studying these processes will reveal new insights to plasma membrane protein function and regulation. Recently, k-Space Image Correlation Spectroscopy (kICS)1 was developed to enable ro...

  9. Aplicando la Metodología PSP para el Desarrollo de un Sistema de Reconocimiento de Gestos

    Directory of Open Access Journals (Sweden)

    Erik Ramos Pérez

    2015-12-01

    Full Text Available MUDI es un sistema reconocedor de gestos, capaz de detectar el acercamiento, rotación y cambiar de pieza arqueológica modeladas en 3D existentes en el MureH. El sistema está contextualizado para un museo interactivo en el que los usuarios puedan descubrir las características de las piezas de una forma entretenida y divertida. Para desarrollar el sistema se utilizó PSP, el cual es una metodología encaminada al proceso personal, establecido y regido por etapas bien establecidas, una de ellas es el diseño que permite tener una buena estructura del sistema traduciéndose en una fácil implementación y control de los errores de codificación, así como el manejo de los requerimientos. Para medir la interacción, efectividad y facilidad de uso de MUDI se usaron técnicas de usabilidad, obteniendo resultados favorables, específicamente el acercamiento tuvo una calificación de 4.8, rotación de 4.0 y cambiar pieza de 4.4 en una escala del 0 al 5. Los usuarios manifestaron gran aceptación y buenos comentarios puesto que con MUDI se olvidaban de las visitas tradicionales.

  10. Diagnosis of Simulated External Root Resorption Using Conventional Intraoral Film Radiography, CCD, PSP, and CBCT: A Comparison Study

    Directory of Open Access Journals (Sweden)

    Abbas Shokri

    2013-02-01

    Full Text Available Background: Diagnosis of external root resorption (ERR cavities may be challenging, especially when no clinical signs are seen. Therefore, the aim of this study was to compare the efficacy of conventional intraoral film radiography, charge-coupled device (CCD detector, photostimulable phosphor plate (PSP detector, and cone beam computed tomography (CBCT for the detection of ERR. Methods: The study sample comprised 54 maxillary first premolars. Cavities were created by using a low-speed handpiece with round diamond burs of 1 mm in diameter. Digital and conventional radiographs were taken from each tooth. Three observers examined all images for the presence of resorption cavities. Data were statistically analyzed with the χ2 test. The reliability and degrees of agreement were also determined by the mean of Cohen's Kappa analysis. Results: The differences between the imaging methods in correct detection of root resorption for all sizes were not significant. For locations of root resorption, significant differences were found between CBCT and other methods in the apical regions. Conclusions: CBCT was only useful for detection of cavities located in the apical one-third of the root, compared to other digital or conventional methods.

  11. Diagnosis of simulated external root resorption using conventional intraoral film radiography, CCD, PSP, and CBCT: a comparison study.

    Science.gov (United States)

    Shokri, Abbas; Mortazavi, Hamed; Salemi, Fatemeh; Javadian, Adineh; Bakhtiari, Hamidreza; Matlabi, Hooman

    2013-01-01

    Diagnosis of external root resorption (ERR) cavities may be challenging, especially when no clinical signs are seen. Therefore, the aim of this study was to compare the efficacy of conventional intraoral film radiography, charge-coupled device (CCD) detector, photostimulable phosphor plate (PSP) detector, and cone beam computed tomography (CBCT) for the detection of ERR. The study sample comprised 54 maxillary first premolars. Cavities were created by using a low-speed handpiece with round diamond burs of 1 mm in diameter. Digital and conventional radiographs were taken from each tooth. Three observers examined all images for the presence of resorption cavities. Data were statistically analyzed with the χ(2) test. The reliability and degrees of agreement were also determined by the mean of Cohen's Kappa analysis. The differences between the imaging methods in correct detection of root resorption for all sizes were not significant. For locations of root resorption, significant differences were found between CBCT and other methods in the apical regions. CBCT was only useful for detection of cavities located in the apical one-third of the root, compared to other digital or conventional methods.

  12. Pressure-Sensitive Paint Measurements on the NASA Common Research Model in the NASA 11-ft Transonic Wind Tunnel

    Science.gov (United States)

    Bell, James H.

    2011-01-01

    The luminescence lifetime technique was used to make pressure-sensitive paint (PSP) measurements on a 2.7% Common Research Model in the NASA Ames 11ft Transonic Wind Tunnel. PSP data were obtained on the upper and lower surfaces of the wing and horizontal tail, as well as one side of the fuselage. Data were taken for several model attitudes of interest at Mach numbers between 0.70 and 0.87. Image data were mapped onto a three-dimensional surface grid suitable both for comparison with CFD and for integration of pressures to determine loads. Luminescence lifetime measurements were made using strobed LED (light-emitting diode) lamps to illuminate the PSP and fast-framing interline transfer cameras to acquire the PSP emission.

  13. The putative thiosulfate sulfurtransferases PspE and GlpE contribute to virulence of Salmonella Typhimurium in the mouse model of systemic disease.

    Directory of Open Access Journals (Sweden)

    Inke Wallrodt

    Full Text Available The phage-shock protein PspE and GlpE of the glycerol 3-phosphate regulon of Salmonella enterica serovar Typhimurium are predicted to belong to the class of thiosulfate sulfurtransferases, enzymes that traffic sulfur between molecules. In the present study we demonstrated that the two genes contribute to S. Typhimurium virulence, as a glpE and pspE double deletion strain showed significantly decreased virulence in a mouse model of systemic infection. However, challenge of cultured epithelial cells and macrophages did not reveal any virulence-associated phenotypes. We hypothesized that their contribution to virulence could be in sulfur metabolism or by contributing to resistance to nitric oxide, oxidative stress, or cyanide detoxification. In vitro studies demonstrated that glpE but not pspE was important for resistance to H2O2. Since the double mutant, which was the one affected in virulence, was not affected in this assay, we concluded that resistance to oxidative stress and the virulence phenotype was most likely not linked. The two genes did not contribute to nitric oxid stress, to synthesis of essential sulfur containing amino acids, nor to detoxification of cyanide. Currently, the precise mechanism by which they contribute to virulence remains elusive.

  14. ICT Statistics at the New Millennium ---Developing Official Statistics---Measuring the Diffusion of ICT and its Impact

    OpenAIRE

    Jeskanen-Sundström, Heli

    2003-01-01

    The paper gives a short and very rough overview of the ongoing work in the field of statistics relating to the development of information and communication technology (ICT) and its impacts on the economies and on the society as a whole. It introduces three slightly different approaches with different emphasis on describing the emergence and diffusion of ICT and the respective economic and social change. These are termed the indicators approach, the new economy approach and the int...

  15. Spread spectrum time-resolved diffuse optical measurement system for enhanced sensitivity in detecting human brain activity

    Science.gov (United States)

    Mehta, Kalpesh; Hasnain, Ali; Zhou, Xiaowei; Luo, Jianwen; Penney, Trevor B.; Chen, Nanguang

    2017-04-01

    Diffuse optical spectroscopy (DOS) and imaging methods have been widely applied to noninvasive detection of brain activity. We have designed and implemented a low cost, portable, real-time one-channel time-resolved DOS system for neuroscience studies. Phantom experiments were carried out to test the performance of the system. We further conducted preliminary human experiments and demonstrated that enhanced sensitivity in detecting neural activity in the cortex could be achieved by the use of late arriving photons.

  16. Measurement of the thermal diffusivity of a silica fiber bundle using a laser and an IR camera

    OpenAIRE

    Vignoles, Gérard; BRESSON, Grégory; Lorrette, Christophe; AHMADI-SENICHAULT, Azita

    2012-01-01

    International audience; We propose a lightweight method for the determination of heat diffusivity of silica fiber bundles based on the use of a laser and an IR camera. The fiber bundle is maintained in traction in a holder; exposition is made as a step function, followed by a laser shutdown. The movie obtained by the IR camera is then processed : frame averaging, backgraound computation and substraction, image smoothing, extraction of the IR signal along the fiber bundle. A 1D model has been ...

  17. Serial measurement of memory and diffusion tensor imaging changes within the first week following uncomplicated mild traumatic brain injury.

    Science.gov (United States)

    Wilde, Elisabeth A; McCauley, Stephen R; Barnes, Amanda; Wu, Trevor C; Chu, Zili; Hunter, Jill V; Bigler, Erin D

    2012-06-01

    Patients (n = 8) with uncomplicated mild traumatic brain injury (mTBI) underwent serial assessments (4) with diffusion tensor imaging (DTI) and neuropsychological testing within the first 8 days post-injury. Using a multi-case study design, we examined changes in brain parenchyma (via DTI-derived fractional anisotropy [FA], apparent diffusion coefficient [ADC], axial diffusivity [AD] and radial diffusivity [RD] in the left cingulum bundle) and in memory performance (via Hopkins Verbal Learning Test-Revised). Qualitative inspection of the results indicated that memory performance was transiently affected in most participants over the course of the week, with performance most negatively impacted on the second assessment (days 3-4 or 97-144 h post-injury), and then returning to within normal limits by 8 days post-injury. Alternatively, FA and other DTI metrics showed a more complex pattern, with the trajectory of some participants changing more prominently than others. For example, FA transiently increased in some participants over the study period, but the pattern was heterogeneous. Memory performance appeared to mirror changes in FA in certain cases, supporting a pathophysiological basis to memory impairment following mTBI. However, the pattern and the degree of symmetry between FA and memory performance was complex and did not always correspond. Serial imaging over the semi-acute recovery period may be important in reconciling conflicting findings in mTBI utilizing memory and/or DTI. Serial use of imaging modalities including DTI may aid understanding of underlying pathophysiological changes in the semi-acute post-injury period. Should a consistent pattern emerge that allows identification of patients at-risk for acute and/or persistent symptoms, such knowledge could guide development of therapeutic targets in mTBI and in understanding the most effective administration time window for these agents.

  18. Using Noise and Fluctuations for In Situ  Measurements of Nitrogen Diffusion Depth

    Directory of Open Access Journals (Sweden)

    Cornel Samoila

    2016-10-01

    Full Text Available In manufacturing processes involving diffusion (of C, N, S, etc., the evolution of the layer depth is of the utmost importance: the success of the entire process depends on this parameter. Currently, nitriding is typically either calibrated using a “post process” method or controlled via indirect measurements (H2, O2, H2O + CO2. In the absence of “in situ” monitoring, any variation in the process parameters (gas concentration, temperature, steel composition, distance between sensors and furnace chamber can cause expensive process inefficiency or failure. Indirect measurements can prevent process failure, but uncertainties and complications may arise in the relationship between the measured parameters and the actual diffusion process. In this paper, a method based on noise and fluctuation measurements is proposed that offers direct control of the layer depth evolution because the parameters of interest are measured in direct contact with the nitrided steel (represented by the active electrode. The paper addresses two related sets of experiments. The first set of experiments consisted of laboratory tests on nitrided samples using Barkhausen noise and yieded a linear relationship between the frequency exponent in the Hooge equation and the nitriding time. For the second set, a specific sensor based on conductivity noise (at the nitriding temperature was built for shop‐floor experiments. Although two different types of noise were measured in these two sets of experiments, the use of the frequency exponent to monitor the process evolution remained valid.

  19. Broadband time-resolved diffuse optical spectrometer for clinical diagnostics: characterization and in-vivo measurements in the 600-1350 nm spectral range

    Science.gov (United States)

    Konugolu Venkata Sekar, Sanathana; Farina, Andrea; Martinenghi, Edoardo; Dalla Mora, Alberto; Taroni, Paola; Pifferi, Antonio; Durduran, Turgut; Pagliazzi, Marco; Lindner, Claus; Farzam, Parisa; Mora, Mireia; Squarcia, Mattia; Urbano-Ispizua, A.

    2015-07-01

    We report on the design, performance assessment, and first in vivo measurement of a Time-Resolved Diffuse Optical system for broadband (600-1350 nm) nm measurement of absorption and scattering spectra of biological tissues for non-invasive clinical diagnostics. Two strategies to reduce drift and enhance responsivity are adopted. The system was enrolled in a first in vivo test phase on healthy volunteers, carrying out non-invasive, in vivo quantification of key tissue constituents (oxy- and deoxy-hemoglobin, water, lipids, collagen) and tissue micro-structure (scatterer size and density).

  20. Temperature dependence of the thermal diffusivity of GaAs in the 100-305 K range measured by the pulsed photothermal displacement technique

    Science.gov (United States)

    Soltanolkotabi, M.; Bennis, G. L.; Gupta, R.

    1999-01-01

    We have measured the variation of the value of the thermal diffusivity of semi-insulating GaAs in the 100-305 K range. The method used is the pulsed photothermal displacement technique. This is a noncontact technique, and the value of the thermal diffusivity is derived from the temporal evolution of the signal rather than its amplitude. This makes the technique less susceptible to uncertainties. We find that the temperature dependence of the thermal conductivity of semi-insulating GaAs follows a power law as T-1.62, in disagreement with results obtained previously. Possible reasons for the deviation within this very important intermediate temperature range are discussed.

  1. Determination of the Thermal Diffusivity of Electrically Non-Conductive Solids in the Temperature Range from 80 K to 300 K by Laser-Flash Measurement

    Science.gov (United States)

    Hemberger, F.; Göbel, A.; Ebert, H.-P.

    2010-12-01

    The adoption of the popular laser-flash method at temperatures far below 300 K is restricted by the weak signal-to-noise ratio and the limited spectral bandwidth of the commonly used mercury cadmium tellurite (MCT) infrared (IR) detector used as a non-contacting temperature probe. In this work, a different approach to measure the temperature rise in pulse heating experiments is described and evaluated. This method utilizes the change of the temperature-dependent electrical resistance of a thin strip of sputtered gold for the detection of a temperature rise as it was proposed by Kogure et al. The main advantage of this method at lower temperatures is the significantly higher signal-to-noise ratio compared to the commonly used IR detectors. A newly developed laser-flash apparatus using this detection method for the determination of the thermal diffusivity in the temperature range from 80 K to 300 K is presented. To test the accuracy of the new detection method, the thermal diffusivity of a borosilicate crown glass (BK7) specimen at 300 K was determined and compared to results derived with a MCT detector. Good agreement of the derived thermal diffusivity values within 3 % was found. The thermal diffusivity of BK7 and polycrystalline aluminum nitride (AlN) was measured at temperatures between 80 K and 300 K by a laser-flash method to test the functionality of the apparatus. Finally, the thermal conductivity was calculated using values for the specific heat capacity determined by temperature modulated differential scanning calorimetry (MDSC). Comparisons with literature data confirm the reliability of the experimental setup.

  2. Measurements of Thermal Conductivity and Thermal Diffusivity of Hen Egg-White Lysozyme Crystals and Its Solution Using the Transient Short Hot Wire Method

    Science.gov (United States)

    Fujiwara, Seiji; Maki, Syou; Maekawa, Ryunosuke; Tanaka, Seiichi; Hagiwara, Masayuki

    2017-08-01

    Protein crystals are an essentially important biological sample to advance the analysis of X-ray structure, but their thermophysical properties, especially thermal conductivity and thermal diffusivity, have not been studied sufficiently. This current situation can be attributed to various kinds of technical problems; e.g., the fragility of protein crystals and the difficulty of nucleation control. Ideally speaking, protein crystallization should be carried out under a " containerless condition" to eliminate any mechanical distortion of the crystals from the walls. To realize the condition, we have developed an original crystallization method by means of the magneto-Archimedes effect. In this paper, a transient short hot wire method was combined with the technique of magneto-Archimedes effect to realize simultaneous measurement of thermal conductivity and thermal diffusivity of hen egg-white lysozyme (HEWL) crystals. As the results, thermal conductivity and thermal diffusivity of HEWL crystals were found to be 0.410-0.438 \\hbox {W}\\cdot \\hbox {m}^{-1}\\cdot \\hbox {K}^{-1} and 3.77-5.18× 10^{-8} \\hbox {m}2\\cdot \\hbox {s}^{-1}, respectively. We clarified by the crystallizing process of HEWL that the crystals were magnetically levitated at the air-liquid interface and the short hot wire was completely buried into them as the crystals grew. We also measured the HEWL solution by the same methods. The thermal conductivity of the solution had almost the same value as that of water and had little dependency on the concentration of HEWL, but the thermal diffusivity was unclear.

  3. Measuring the Quality of Generalized Gradient Approximations in a Density Functional Theory Pseudopotential Environment for Solids

    Science.gov (United States)

    Nault, Zachary; Cancio, Antonio

    2013-03-01

    Much recent development in DFT has focused on improving GGAs. Two schemes are second order GGA (SOGGA) and the APBE which builds the GGA from atomic systems and not the HEG. Both of these have been tested within an all electron (AE) environment, providing the most accurate results. The focus of many simulations, however, is on large systems using pseudopotentials (PsP's). Are these PsP calculations, which rely on functionals tested in an AE environment, accurately reproducing the AE ground state properties? If not, can the deficiencies be identified? To assess this, we use the PsP generator APE, using the functional library libXC which works with the PsP package ABINIT and the AE package Elk. We generate standard Troullier-Martin PsP's based on common and new XC functionals (LDA, PBE, PBEsol, APBE, SOGGA) and test their performance in 13 solids (Na, Li, Al, C, Si, GaAs, NaCl, LiF, LiCl, Cu, Pd, Rh, and Ag). We measure how well three ground state properties (lattice constant, bulk modulus, and cohesive energy) are calculated with PsP's as compared to the corresponding AE calculations.

  4. The High Resolution Imaging Science Experiment (HiRISE) during MRO's Primary Science Phase (PSP)

    Science.gov (United States)

    McEwen, A.S.; Banks, M.E.; Baugh, N.; Becker, K.; Boyd, A.; Bergstrom, J.W.; Beyer, R.A.; Bortolini, E.; Bridges, N.T.; Byrne, S.; Castalia, B.; Chuang, F.C.; Crumpler, L.S.; Daubar, I.; Davatzes, A.K.; Deardorff, D.G.; DeJong, A.; Alan, Delamere W.; Dobrea, E.N.; Dundas, C.M.; Eliason, E.M.; Espinoza, Y.; Fennema, A.; Fishbaugh, K.E.; Forrester, T.; Geissler, P.E.; Grant, J. A.; Griffes, J.L.; Grotzinger, J.P.; Gulick, V.C.; Hansen, C.J.; Herkenhoff, K. E.; Heyd, R.; Jaeger, W.L.; Jones, D.; Kanefsky, B.; Keszthelyi, L.; King, R.; Kirk, R.L.; Kolb, K.J.; Lasco, J.; Lefort, A.; Leis, R.; Lewis, K.W.; Martinez-Alonso, S.; Mattson, S.; McArthur, G.; Mellon, M.T.; Metz, J.M.; Milazzo, M.P.; Milliken, R.E.; Motazedian, T.; Okubo, C.H.; Ortiz, A.; Philippoff, A.J.; Plassmann, J.; Polit, A.; Russell, P.S.; Schaller, C.; Searls, M.L.; Spriggs, T.; Squyres, S. W.; Tarr, S.; Thomas, N.; Thomson, B.J.; Tornabene, L.L.; Van Houten, C.; Verba, C.; Weitz, C.M.; Wray, J.J.

    2010-01-01

    The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ???0.55% of the surface. Images are typically 5-6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25 to 60 cm/pixel. Nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models (DTMs) completed; these data have led to some of the most significant science results. New methods to measure and correct distortions due to pointing jitter facilitate topographic and change-detection studies at sub-meter scales. Recent results address Noachian bedrock stratigraphy, fluvially deposited fans in craters and in or near Valles Marineris, groundwater flow in fractures and porous media, quasi-periodic layering in polar and non-polar deposits, tectonic history of west Candor Chasma, geometry of clay-rich deposits near and within Mawrth Vallis, dynamics of flood lavas in the Cerberus Palus region, evidence for pyroclastic deposits, columnar jointing in lava flows, recent collapse pits, evidence for water in well-preserved impact craters, newly discovered large rayed craters, and glacial and periglacial processes. Of particular interest are ongoing processes such as those driven by the wind, impact cratering, avalanches of dust and/or frost, relatively bright deposits on steep gullied slopes, and the dynamic seasonal processes over polar regions. HiRISE has acquired hundreds of large images of past, present and potential future landing sites and has contributed to scientific and engineering studies of those sites. Warming the focal-plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions. ?? 2009 Elsevier Inc.

  5. Diffusion coefficient, porosity measurement, dynamic and equilibrium swelling studies of Acrylic acid/Polyvinyl alcohol (AA/PVA hydrogels

    Directory of Open Access Journals (Sweden)

    Nazar Mohammad Ranjha

    2015-06-01

    Full Text Available Objective of the present work was to synthesize hydrogels of acrylic acid/polyvinyl alcohol (AA/PVA by free radical polymerization by using glutaradehyde (GA as crosslinkers. The hydrogels were evaluated for swelling, diffusion coefficient and network parameters like the average molecular weight between crosslink’s, polymer volume fraction in swollen state, number of repeating units between crosslinks and crosslinking density by using Flory-Huggins theory. It was found that the degree of swelling of AA/PVA hydrogels increases greatly within the pH range 5-7. The gel fraction and porosity increased by increasing the concentration of AA or PVA. Increase in degree of crosslinking, decreased the porosity and inverse was observed in gel fraction. Selected samples were loaded with metoprolol tartrate. Drug release was studied in USP hydrochloric acid solution of pH 1.2 and phosphate buffer solutions of pH 5.5 and 7.5. Various kinetics models like zero order, first order, Higuchi and Peppas model were used for in vitro kinetic studies. The results showed that the drug release followed concentration dependent effect (First order kinetics with non-Fickian diffusion. FTIR and SEM used to study the structure, crystallinity, compatibility, thermal stability and morphology of prepared and drug loaded hydrogels respectively.

  6. Estimates of DNA strand breakage in bottlenose dolphin (Tursiops truncatus leukocytes measured with the Comet and DNA diffusion assays

    Directory of Open Access Journals (Sweden)

    Adriana Díaz

    2009-01-01

    Full Text Available The analysis of DNA damage by mean of Comet or single cell gel electrophoresis (SCGE assay has been commonly used to assess genotoxic impact in aquatic animals being able to detect exposure to low concentrations of contaminants in a wide range of species. The aims of this work were 1 to evaluate the usefulness of the Comet to detect DNA strand breakage in dolphin leukocytes, 2 to use the DNA diffusion assay to determine the amount of DNA strand breakage associated with apoptosis or necrosis, and 3 to determine the proportion of DNA strand breakage that was unrelated to apoptosis and necrosis. Significant intra-individual variation was observed in all of the estimates of DNA damage. DNA strand breakage was overestimated because a considerable amount (~29% of the DNA damage was derived from apoptosis and necrosis. The remaining DNA damage in dolphin leukocytes was caused by factors unrelated to apoptosis and necrosis. These results indicate that the DNA diffusion assay is a complementary tool that can be used together with the Comet assay to assess DNA damage in bottlenose dolphins.

  7. Symmetry of the gradient profile as second experimental dimension in the short-time expansion of the apparent diffusion coefficient as measured with NMR diffusometry.

    Science.gov (United States)

    Laun, Frederik Bernd; Kuder, Tristan Anselm; Zong, Fangrong; Hertel, Stefan; Galvosas, Petrik

    2015-10-01

    The time-dependent apparent diffusion coefficient as measured by pulsed gradient NMR can be used to estimate parameters of porous structures including the surface-to-volume ratio and the mean curvature of pores. In this work, the short-time diffusion limit and in particular the influence of the temporal profile of diffusion gradients on the expansion as proposed by Mitra et al. (1993) is investigated. It is shown that flow-compensated waveforms, i.e. those whose first moment is zero, are blind to the term linear in observation time, which is the term that is proportional to mean curvature and surface permeability. A gradient waveform that smoothly interpolates between flow-compensated and bipolar waveform is proposed and the degree of flow-compensation is used as a second experimental dimension. This two-dimensional ansatz is shown to yield an improved precision when characterizing the confining domain. This technique is demonstrated with simulations and in experiments performed with cylindrical capillaries of 100 μm radius. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Oxygen diffusion in Y sub 1 sub - sub x Pr sub x Ba sub 2 Cu sub 3 O sub 7 sub - subdelta observed by resistivity measurements

    CERN Document Server

    Diosa, J E; Mellander, B E

    1997-01-01

    In situ resistivity measurements have been used to monitor the oxygen uptake and removal for the ceramic system Y sub 1 sub - sub x Pr sub x Ba sub 2 Cu sub 3 O sub 7 sub - subdelta (YPBCO) in the temperature range 300 - 1000 K. The study of the out-diffusion of oxygen was performed by annealing the oxygenated samples in ambient air at constant heating rates. We found that, independently of x, the oxygen concentration O sub 7 sub - subdelta is preserved up to 600 K, and that oxygen diffuses out of the oxides at temperatures higher than 600 K. However, the rate of oxygen removal from PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta (PBCO) is greatly reduced as compared to the rate for pure YBa sub 2 Cu sub 3 O sub 7 sub - subdelta (YBCO), and decreases with increasing x in YPBCO. The study of the in-diffusion of oxygen was performed by annealing the deoxygenated samples in ambient air at constant heating rates. We found that, independently of x, the oxygen uptake takes place in the temperature range 550 - 750 K, whe...

  9. Simultaneous Measurement of Thermal Diffusivity and Thermal Conductivity by Means of Inverse Solution for One-Dimensional Heat Conduction (Anisotropic Thermal Properties of CFRP for FCEV)

    Science.gov (United States)

    Kosaka, Masataka; Monde, Masanori

    2015-11-01

    For safe and fast fueling of hydrogen in a fuel cell electric vehicle at hydrogen fueling stations, an understanding of the heat transferred from the gas into the tank wall (carbon fiber reinforced plastic (CFRP) material) during hydrogen fueling is necessary. Its thermal properties are needed in estimating heat loss accurately during hydrogen fueling. The CFRP has anisotropic thermal properties, because it consists of an adhesive agent and layers of the CFRP which is wound with a carbon fiber. In this paper, the thermal diffusivity and thermal conductivity of the tank wall material were measured by an inverse solution for one-dimensional unsteady heat conduction. As a result, the thermal diffusivity and thermal conductivity were 2.09 × 10^{-6}{ m}2{\\cdot }{s}^{-1} and 3.06{ W}{\\cdot }{m}{\\cdot }^{-1}{K}^{-1} for the axial direction, while they were 6.03 × 10^{-7} {m}2{\\cdot }{s}^{-1} and 0.93 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} for the radial direction. The thermal conductivity for the axial direction was about three times higher than that for the radial direction. The thermal diffusivity shows the same trend in both directions because the thermal capacity, ρ c, is independent of direction, where ρ is the density and c is the heat capacity.

  10. Advancing Solar Irradiance Measurement for Climate-Related Studies: Accurate Constraint on Direct Aerosol Radiative Effect (DARE)

    Science.gov (United States)

    Tsay, Si-Chee; Ji, Q. Jack

    2011-01-01

    Earth's climate is driven primarily by solar radiation. As summarized in various IPCC reports, the global average of radiative forcing for different agents and mechanisms, such as aerosols or CO2 doubling, is in the range of a few W/sq m. However, when solar irradiance is measured by broadband radiometers, such as the fleet of Eppley Precision Solar Pyranometers (PSP) and equivalent instrumentation employed worldwide, the measurement uncertainty is larger than 2% (e.g., WMO specification of pyranometer, 2008). Thus, out of the approx. 184 W/sq m (approx.263 W/sq m if cloud-free) surface solar insolation (Trenberth et al. 2009), the measurement uncertainty is greater than +/-3.6 W/sq m, overwhelming the climate change signals. To discern these signals, less than a 1 % measurement uncertainty is required and is currently achievable only by means of a newly developed methodology employing a modified PSP-like pyranometer and an updated calibration equation to account for its thermal effects (li and Tsay, 2010). In this talk, we will show that some auxiliary measurements, such as those from a collocated pyrgeometer or air temperature sensors, can help correct historical datasets. Additionally, we will also demonstrate that a pyrheliometer is not free of the thermal effect; therefore, comparing to a high cost yet still not thermal-effect-free "direct + diffuse" approach in measuring surface solar irradiance, our new method is more economical, and more likely to be suitable for correcting a wide variety of historical datasets. Modeling simulations will be presented that a corrected solar irradiance measurement has a significant impact on aerosol forcing, and thus plays an important role in climate studies.

  11. Apparent diffusion coefficient measurements in diffusion-weighted magnetic resonance imaging of the anterior mediastinum: inter-observer reproducibility of five different methods of region-of-interest positioning

    Energy Technology Data Exchange (ETDEWEB)

    Priola, Adriano Massimiliano; Priola, Sandro Massimo; Parlatano, Daniela; Gned, Dario; Veltri, Andrea [San Luigi Gonzaga University Hospital, Department of Diagnostic Imaging, Regione Gonzole 10, Orbassano, Torino (Italy); Giraudo, Maria Teresa [University of Torino, Department of Mathematics ' ' Giuseppe Peano' ' , Torino (Italy); Giardino, Roberto; Ardissone, Francesco [San Luigi Gonzaga University Hospital, Department of Thoracic Surgery, Regione Gonzole 10, Orbassano, Torino (Italy); Ferrero, Bruno [San Luigi Gonzaga University Hospital, Department of Neurology, Regione Gonzole 10, Orbassano, Torino (Italy)

    2017-04-15

    To investigate inter-reader reproducibility of five different region-of-interest (ROI) protocols for apparent diffusion coefficient (ADC) measurements in the anterior mediastinum. In eighty-one subjects, on ADC mapping, two readers measured the ADC using five methods of ROI positioning that encompassed the entire tissue (whole tissue volume [WTV], three slices observer-defined [TSOD], single-slice [SS]) or the more restricted areas (one small round ROI [OSR], multiple small round ROI [MSR]). Inter-observer variability was assessed with interclass correlation coefficient (ICC), coefficient of variation (CoV), and Bland-Altman analysis. Nonparametric tests were performed to compare the ADC between ROI methods. The measurement time was recorded and compared between ROI methods. All methods showed excellent inter-reader agreement with best and worst reproducibility in WTV and OSR, respectively (ICC, 0.937/0.874; CoV, 7.3 %/16.8 %; limits of agreement, ±0.44/±0.77 x 10{sup -3} mm{sup 2}/s). ADC values of OSR and MSR were significantly lower compared to the other methods in both readers (p < 0.001). The SS and OSR methods required less measurement time (14 ± 2 s) compared to the others (p < 0.0001), while the WTV method required the longest measurement time (90 ± 56 and 77 ± 49 s for each reader) (p < 0.0001). All methods demonstrate excellent inter-observer reproducibility with the best agreement in WTV, although it requires the longest measurement time. (orig.)

  12. Speckle reducing anisotropic diffusion.

    Science.gov (United States)

    Yu, Yongjian; Acton, Scott T

    2002-01-01

    This paper provides the derivation of speckle reducing anisotropic diffusion (SRAD), a diffusion method tailored to ultrasonic and radar imaging applications. SRAD is the edge-sensitive diffusion for speckled images, in the same way that conventional anisotropic diffusion is the edge-sensitive diffusion for images corrupted with additive noise. We first show that the Lee and Frost filters can be cast as partial differential equations, and then we derive SRAD by allowing edge-sensitive anisotropic diffusion within this context. Just as the Lee and Frost filters utilize the coefficient of variation in adaptive filtering, SRAD exploits the instantaneous coefficient of variation, which is shown to be a function of the local gradient magnitude and Laplacian operators. We validate the new algorithm using both synthetic and real linear scan ultrasonic imagery of the carotid artery. We also demonstrate the algorithm performance with real SAR data. The performance measures obtained by means of computer simulation of carotid artery images are compared with three existing speckle reduction schemes. In the presence of speckle noise, speckle reducing anisotropic diffusion excels over the traditional speckle removal filters and over the conventional anisotropic diffusion method in terms of mean preservation, variance reduction, and edge localization.

  13. Diffuse pollution by persistent organic pollutants as measured in plastic pellets sampled from various beaches in Greece.

    Science.gov (United States)

    Karapanagioti, H K; Endo, S; Ogata, Y; Takada, H

    2011-02-01

    Plastic pellets found stranded on beaches are hydrophobic organic materials and thus, they are a favourable medium for persistent organic pollutants to absorb to. In the present study, plastic pellets are used to determine the diffuse pollution of selected Greek beaches. Samples of pellets were taken from these beaches and were analyzed for PCBs, DDTs, HCHs, and PAHs. The observed differences among pellets from various sampling sites are related to the pollution occurring at each site. Plastic pellets collected in Saronikos Gulf beaches demonstrate much higher pollutant loading than the ones collected in a remote island or close to an agricultural area. Based on data collected in this study and the International Pellet Watch program, pollution in Saronikos Gulf, Greece, is comparable to other heavily industrialized places of the world. The present study demonstrates the potential of pellet watch to be utilized as a detailed-scale monitoring tool within a single country. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Impact of acid diffusion length on resist LER and LWR measured by CD-AFM and CD-SEM

    Science.gov (United States)

    Foucher, J.; Pikon, A.; Andes, C.; Thackeray, J.

    2007-03-01

    The improvement of devices performances is due to many factors such as new architectures, new materials and better lithography resolution. Resist chemical components play a key role in the final performance of a specific resist. In addition to resist characteristics such as: resolution, etching selectivity, the final resist line edge roughness (LER) and line width roughness (LWR) becomes a critical issue because it can degrade resolution and linewidth accuracy and causes fluctuations of transistors performances 1,2. LER and LWR are currently calculated with top-down view SEM images. With chemically amplified resists, we can play on photoacid generator size to partially control acid diffusion length during the post exposure bake. In this paper we propose to compare two techniques, the CD-AFM and CD SEM in order to study the impact of various acid diffusion lengths on LER and LWR. The results show that globally the two techniques agree on most of the results and show the same trends. However, when the profiles vary the linearity between the two techniques can vary drastically. In addition, as a complementary technique to the CD-SEM technique, the CD-AFM gives additional information such as height (top loss), top rounding and sidewall angle which allow us to understand more deeply the impact of PAG size. Therefore, these additional information have a non negligible impact on near term new resist development and lithography processes development. As an illustration of this work, we will present the latest resist development coming from this understanding and leading to very low LER and LWR. Finally, we will propose strengths and weakness of each technique.

  15. Predilation, sizing and post-dilation scoring in patients undergoing everolimus-eluting bioresorbable scaffold implantation for prediction of cardiac adverse events: development and internal validation of the PSP score.

    Science.gov (United States)

    Ortega-Paz, Luis; Capodanno, Davide; Gori, Tommaso; Nef, Holger; Latib, Azeem; Caramanno, Giuseppe; Di Mario, Carlo; Naber, Christoph; Lesiak, Maciej; Capranzano, Piera; Wiebe, Jens; Mehilli, Julinda; Araszkiewicz, Aleksander; Pyxaras, Stelios; Mattesini, Alessio; Geraci, Salvatore; Naganuma, Toru; Colombo, Antonio; Münzel, Thomas; Sabaté, Manel; Tamburino, Corrado; Brugaletta, Salvatore

    2017-04-20

    The aim of the study was to develop a scoring model to evaluate the quality of bioresorbable vascular scaffold (BVS) implantation and determine the model's usefulness in predicting adverse cardiac events. The implantation technique and clinical outcomes of 1,736 lesions treated with BVS were analysed using the GHOST-EU registry. Predilation, scaffold sizing, and post-dilation (PSP) were scored according to the hazard model derived from the weight of these variables. The primary endpoint was a one-year device-oriented composite endpoint (DoCE) composed of cardiac death, target vessel myocardial infarction, and clinically driven target lesion revascularisation. Definite/probable scaffold thrombosis was also evaluated as defined by the Academic Research Consortium. The PSP model performance was evaluated by internal validation. Predilation, correct scaffold sizing, and post-dilation with a non-compliant balloon were performed in 95.7%, 50.2%, and 26.2% of the cases and scored 0.63, 1.96 and 1.93 points, respectively, in the PSP-1 model. PSP-1 was an independent predictor of one-year DoCE (HR 0.75, 95% CI: 0.61-0.93; p=0.007), but with poor calibration and discrimination (AUC 0.611, 95% CI: 0.545-0.677). No patient with a maximum PSP-1 score had scaffold thrombosis, compared to those with a non-maximum PSP-1 score (0% vs. 2.3%; p=0.095). At one-year follow-up, the PSP-1 score was an independent predictor of DoCE. External validation and prospective studies are needed to determine the clinical usefulness of this score.

  16. Matching the reaction-diffusion simulation to dynamic [18F]FMISO PET measurements in tumors: extension to a flow-limited oxygen-dependent model.

    Science.gov (United States)

    Shi, Kuangyu; Bayer, Christine; Gaertner, Florian C; Astner, Sabrina T; Wilkens, Jan J; Nüsslin, Fridtjof; Vaupel, Peter; Ziegler, Sibylle I

    2017-02-01

    Positron-emission tomography (PET) with hypoxia specific tracers provides a noninvasive method to assess the tumor oxygenation status. Reaction-diffusion models have advantages in revealing the quantitative relation between in vivo imaging and the tumor microenvironment. However, there is no quantitative comparison of the simulation results with the real PET measurements yet. The lack of experimental support hampers further applications of computational simulation models. This study aims to compare the simulation results with a preclinical [18F]FMISO PET study and to optimize the reaction-diffusion model accordingly. Nude mice with xenografted human squamous cell carcinomas (CAL33) were investigated with a 2 h dynamic [18F]FMISO PET followed by immunofluorescence staining using the hypoxia marker pimonidazole and the endothelium marker CD 31. A large data pool of tumor time-activity curves (TAC) was simulated for each mouse by feeding the arterial input function (AIF) extracted from experiments into the model with different configurations of the tumor microenvironment. A measured TAC was considered to match a simulated TAC when the difference metric was below a certain, noise-dependent threshold. As an extension to the well-established Kelly model, a flow-limited oxygen-dependent (FLOD) model was developed to improve the matching between measurements and simulations. The matching rate between the simulated TACs of the Kelly model and the mouse PET data ranged from 0 to 28.1% (on average 9.8%). By modifying the Kelly model to an FLOD model, the matching rate between the simulation and the PET measurements could be improved to 41.2-84.8% (on average 64.4%). Using a simulation data pool and a matching strategy, we were able to compare the simulated temporal course of dynamic PET with in vivo measurements. By modifying the Kelly model to a FLOD model, the computational simulation was able to approach the dynamic [18F]FMISO measurements in the investigated tumors.

  17. An evaluation of ferrihydrite- and Metsorb™-DGT techniques for measuring oxyanion species (As, Se, V, P): effective capacity, competition and diffusion coefficients.

    Science.gov (United States)

    Price, Helen L; Teasdale, Peter R; Jolley, Dianne F

    2013-11-25

    This study investigated several knowledge gaps with respect to the diffusive gradients in thin films (DGT) technique for measurement of oxyanions (As(III), As(V), Se(IV), Se(VI), PO4(3-), and V(V)) using the ferrihydrite and Metsorb™ binding layers. Elution efficiencies for each binding layer were higher with 1:20 dilutions, as analytical interferences for ICP-MS were minimised. Diffusion coefficients measured by diffusion cell and by DGT time-series experiments were found to agree well and generally agreed with previously reported values, although a range of diffusion coefficients have been reported for inorganic As and Se species. The relative binding affinity for both ferrihydrite and Metsorb™ was PO4(3-) ≈ As(V)>V(V) ≈ As(III)>Se(IV) > Se(VI) and effective binding capacities were measured in single ion solutions, and spiked synthetic freshwater and seawater, advising practical decisions about DGT monitoring. Under the conditions tested the performance of both ferrihydrite and Metsorb™ binding layers was directly comparable for As(V), As(III) Se(IV), V(V) and PO4(3-) over a deployment spanning ≤ 2 days for both freshwater and seawater. In order to return quantitative data for several analytes we recommend that the DGT method using either ferrihydrite or Metsorb™ be deployed for a maximum of 2 days in marine waters likely to contain high levels of the most strongly adsorbing oxyanions contaminants. The high pH, the competitive ions present in seawater and the identity of co-adsorbing ions affect the capacity of each binding layer for the analytes of interest. In freshwaters, longer deployment times can be considered but the concentration and identity of co-adsorbing ions may impact on quantitative uptake of Se(IV). This study found ferrihydrite-DGT outperformed Metsorb-DGT while previous studies have found the opposite, with variation in binding materials masses used being a likely reason. Clearly, preparation of both binding layers should always be

  18. The putative thiosulfate sulfurtransferases PspE and GlpE contribute to virulence of Salmonella Typhimurium in the mouse model of systemic disease

    DEFF Research Database (Denmark)

    Wallrodt, Inke; Jelsbak, Lotte; Thorndahl, Lotte

    2013-01-01

    that their contribution to virulence could be in sulfur metabolism or by contributing to resistance to nitric oxide, oxidative stress, or cyanide detoxification. In vitro studies demonstrated that glpE but not pspE was important for resistance to H2O2. Since the double mutant, which was the one affected in virulence......, was not affected in this assay, we concluded that resistance tooxidative stress and the virulence phenotype was most likely not linked. The two genes did not contribute to nitric oxide stress, to synthesis of essential sulfur containing amino acids, nor to detoxification of cyanide. Currently, the precise...

  19. Development of a diffusion-weighted MRI protocol for multi-centre abdominal imaging and evaluation of the effects of fasting on measurement of apparent diffusion coefficients (ADCs) in healthy liver

    NARCIS (Netherlands)

    Winfield, J.M.; Papoutsaki, M.-V.; Ragheb, H.; Morris, D.M.; Heerschap, A.; Voert, E.G.W. Ter; Kuijer, J.P.A.; Pieters, I.C.; Douglas, N.H.M.; Orton, M.; Desouza, N.M.

    2015-01-01

    To assess the effect of fasting and eating on estimates of apparent diffusion coefficient (ADC) in the livers of healthy volunteers using a diffusion-weighted magnetic resonance imaging (DW-MRI) protocol with b-values of 100, 500 and 900 s/mm(2) in a multicentre study at 1.5 T.Twenty volunteers were

  20. Development of a diffusion-weighted MRI protocol for multicentre abdominal imaging and evaluation of the effects of fasting on measurement of apparent diffusion coefficients (ADCs) in healthy liver

    NARCIS (Netherlands)

    Winfield, J.M.; Papoutsaki, M.V.; Ragheb, H.; Morris, D.M.; Heerschap, A.; Voert, E.G.W. Ter; Kuijer, J.P.A.; Pieters, I.C.; Douglas, N.H.M.; Orton, M.; Souza, N.M. de; Qu, I.C.C.C.

    2015-01-01

    OBJECTIVE: To assess the effect of fasting and eating on estimates of apparent diffusion coefficient (ADC) in the livers of healthy volunteers using a diffusion-weighted MRI protocol with b-values of 100, 500 and 900 s mm(-2) in a multicentre study at 1.5 T. METHODS: 20 volunteers were scanned using

  1. Development of a diffusion-weighted MRI protocol for multicentre abdominal imaging and evaluation of the effects of fasting on measurement of apparent diffusion coefficients (ADCs) in healthy liver

    NARCIS (Netherlands)

    Winfield, J.M.; Papoutsaki, M.V.; Ragheb, H.; Morris, D.M.; Heerschap, A.; ter Voert, E.G.W.; Kuijer, J.P.A.; Pieters, I.C.; Douglas, N.H.M.; Orton, M.; de Souza, N.M.

    2015-01-01

    Objective: To assess the effect of fasting and eating on estimates of apparent diffusion coefficient (ADC) in the livers of healthy volunteers using a diffusion-weighted MRI protocol with b-values of 100, 500 and 900smm-2 in a multicentre study at 1.5 T. Methods: 20 volunteers were scanned using 4

  2. Intra- and interrater reliability of ischemic lesion volume measurements on diffusion-weighted, mean transit time and fluid-attenuated inversion recovery MRI.

    Science.gov (United States)

    Luby, Marie; Bykowski, Julie L; Schellinger, Peter D; Merino, José G; Warach, Steven

    2006-12-01

    We investigated the intra- and interrater reliability of ischemic lesion volumes measurements assessed by different MRI sequences at various times from onset. Ischemic lesion volumes were measured for intrarater reliability using diffusion-weighted (DWI), mean transit time (MTT) perfusion and fluid-attenuated inversion recovery (FLAIR) MRI at chronic (>3 days from stroke onset) time points. A single intrarater reader, blind to clinical information and time point, repeated the volume measurements on two occasions separated by at least 1 week. Interrater reliability was also obtained in the second set of patients using acute DWI, MTT and chronic FLAIR MRI. Four blinded readers performed these volume measurements. Average deviations across repeat measurements per lesion and differences between sample means between the two measurements were calculated globally, ie, across all sequences and time points, and per reader type for each sequence at each time point. There was good concordance of the mean sample volumes of the 2 intrarater readings (deviations were <4% and 2 mL globally, <2% and 2 mL for DWI, <6% and 7 mL for MTT, and <2% and 1 mL for FLAIR). There was also good concordance of the interrater readings (<5% and 2 mL globally). Repeat measurements of stroke lesion volumes show excellent intra- and interrater concordance for DWI, MTT and FLAIR at acute through chronic time points.

  3. Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurments of diffuse light

    NARCIS (Netherlands)

    Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton; Steenbergen, Wiendelt

    2007-01-01

    The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a

  4. New sensitive micro-measurements of dynamic surface tension and diffusion coefficients: Validated and tested for the adsorption of 1-Octanol at a microscopic air-water interface and its dissolution into water.

    Science.gov (United States)

    Kinoshita, Koji; Parra, Elisa; Needham, David

    2017-02-15

    Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain "dead time" at initial measurement. These limitations create inconsistencies for the kinetic analysis of surfactant adsorption/desorption, especially significant for ionic surfactants. Here, the "micropipette interfacial area-expansion method" was introduced and validated as a new DST measurement having a high enough sensitivity to detect diffusion controlled molecular adsorption at the air-water interfaces. To validate the new technique, the diffusion coefficient of 1-Octanol in water was investigated with existing models: the Ward Tordai model for the long time adsorption regime (1-100s), and the Langmuir and Frumkin adsorption isotherm models for surface excess concentration. We found that the measured diffusion coefficient of 1-Octanol, 7.2±0.8×10 -6 cm 2 /s, showed excellent agreement with the result from an alternative method, "single microdroplet catching method", to measure the diffusion coefficient from diffusion-controlled microdroplet dissolution, 7.3±0.1×10 -6 cm 2 /s. These new techniques for determining adsorption and diffusion coefficients can apply for a range of surface active molecules, especially the less-characterized ionic surfactants, and biological compounds such as lipids, peptides, and proteins. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Biases in Metallicity Measurements from Global Galaxy Spectra: The Effects of Flux Weighting and Diffuse Ionized Gas Contamination

    Science.gov (United States)

    Sanders, Ryan L.; Shapley, Alice E.; Zhang, Kai; Yan, Renbin

    2017-12-01

    Galaxy metallicity scaling relations provide a powerful tool for understanding galaxy evolution, but obtaining unbiased global galaxy gas-phase oxygen abundances requires proper treatment of the various line-emitting sources within spectroscopic apertures. We present a model framework that treats galaxies as ensembles of H II and diffuse ionized gas (DIG) regions of varying metallicities. These models are based upon empirical relations between line ratios and electron temperature for H II regions, and DIG strong-line ratio relations from SDSS-IV MaNGA IFU data. Flux-weighting effects and DIG contamination can significantly affect properties inferred from global galaxy spectra, biasing metallicity estimates by more than 0.3 dex in some cases. We use observationally motivated inputs to construct a model matched to typical local star-forming galaxies, and quantify the biases in strong-line ratios, electron temperatures, and direct-method metallicities as inferred from global galaxy spectra relative to the median values of the H II region distributions in each galaxy. We also provide a generalized set of models that can be applied to individual galaxies or galaxy samples in atypical regions of parameter space. We use these models to correct for the effects of flux-weighting and DIG contamination in the local direct-method mass-metallicity and fundamental metallicity relations, and in the mass-metallicity relation based on strong-line metallicities. Future photoionization models of galaxy line emission need to include DIG emission and represent galaxies as ensembles of emitting regions with varying metallicity, instead of as single H II regions with effective properties, in order to obtain unbiased estimates of key underlying physical properties.

  6. Conventional 3T brain MRI and diffusion tensor imaging in the diagnostic workup of early stage parkinsonism

    Energy Technology Data Exchange (ETDEWEB)

    Meijer, Frederick J.A. [Radboud University Nijmegen Medical Center, Department of Radiology and Nuclear Medicine, Nijmegen (Netherlands); Rumund, Anouke van; Tuladhar, Anil M.; Aerts, Marjolein B.; Titulaer, Imke; Esselink, Rianne A.J.; Bloem, Bastiaan R. [Radboud University Nijmegen Medical Center, Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen (Netherlands); Verbeek, Marcel M. [Radboud University Nijmegen Medical Center, Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen (Netherlands); Radboud University Nijmegen Medical Center, Department of Laboratory Medicine, Nijmegen (Netherlands); Goraj, Bozena [Radboud University Nijmegen Medical Center, Department of Radiology and Nuclear Medicine, Nijmegen (Netherlands); Medical Center of Postgraduate Education, Department of Diagnostic Imaging, Warsaw (Poland)

    2015-07-15

    The aim of this study is to evaluate whether the diagnostic accuracy of 3 T brain MRI is improved by region of interest (ROI) measures of diffusion tensor imaging (DTI), to differentiate between neurodegenerative atypical parkinsonism (AP) and Parkinson's disease (PD) in early stage parkinsonism. We performed a prospective observational cohort study of 60 patients presenting with early stage parkinsonism and initial uncertain diagnosis. At baseline, patients underwent a 3 T brain MRI including DTI. After clinical follow-up (mean 28.3 months), diagnoses could be made in 49 patients (30 PD and 19 AP). Conventional brain MRI was evaluated for regions of atrophy and signal intensity changes. Tract-based spatial statistics and ROI analyses of DTI were performed to analyze group differences in mean diffusivity (MD) and fractional anisotropy (FA), and diagnostic thresholds were determined. Diagnostic accuracy of conventional brain MRI and DTI was assessed with the receiver operating characteristic (ROC). Significantly higher MD of the centrum semiovale, body corpus callosum, putamen, external capsule, midbrain, superior cerebellum, and superior cerebellar peduncles was found in AP. Significantly increased MD of the putamen was found in multiple system atrophy-parkinsonian form (MSA-P) and increased MD in the midbrain and superior cerebellar peduncles in progressive supranuclear palsy (PSP). The diagnostic accuracy of brain MRI to identify AP as a group was not improved by ROI measures of MD, though the diagnostic accuracy to identify MSA-P was slightly increased (AUC 0.82 to 0.85). The diagnostic accuracy of brain MRI to identify AP as a group was not improved by the current analysis approach to DTI, though DTI measures could be of added value to identify AP subgroups. (orig.)

  7. Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurments of diffuse light

    OpenAIRE

    Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton; Steenbergen, Wiendelt

    2007-01-01

    The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a turbid suspension of particles undergoing Brownian and translational motion. The path length resolution of this instrument is compared with a system using single mode fibers for illumination and de...

  8. Theory and experiments on surface diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Silvestri, W.L.

    1998-11-01

    The following topics were dealt with: adatom formation and self-diffusion on the Ni(100) surface, helium atom scattering measurements, surface-diffusion parameter measurements, embedded atom method calculations.

  9. On Diffusion and Permeation

    KAUST Repository

    Peppin, Stephen S. L.

    2009-01-01

    Diffusion and permeation are discussed within the context of irreversible thermodynamics. A new expression for the generalized Stokes-Einstein equation is obtained which links the permeability to the diffusivity of a two-component solution and contains the poroelastic Biot-Willis coefficient. The theory is illustrated by predicting the concentration and pressure profiles during the filtration of a protein solution. At low concentrations the proteins diffuse independently while at higher concentrations they form a nearly rigid porous glass through which the fluid permeates. The theoretically determined pressure drop is nonlinear in the diffusion regime and linear in the permeation regime, in quantitative agreement with experimental measurements. © 2009 Walter de Gruyter, Berlin, New York.

  10. Experimental study of an optimized PSP-OSTBC scheme with m-PPM in ultraviolet scattering channel for optical MIMO system.

    Science.gov (United States)

    Han, Dahai; Gu, Yanjie; Zhang, Min

    2017-08-10

    An optimized scheme of pulse symmetrical position-orthogonal space-time block codes (PSP-OSTBC) is proposed and applied with m-pulse positions modulation (m-PPM) without the use of a complex decoding algorithm in an optical multi-input multi-output (MIMO) ultraviolet (UV) communication system. The proposed scheme breaks through the limitation of the traditional Alamouti code and is suitable for high-order m-PPM in a UV scattering channel, verified by both simulation experiments and field tests with specific parameters. The performances of 1×1, 2×1, and 2×2 PSP-OSTBC systems with 4-PPM are compared experimentally as the optimal tradeoff between modification and coding in practical application. Meanwhile, the feasibility of the proposed scheme for 8-PPM is examined by a simulation experiment as well. The results suggest that the proposed scheme makes the system insensitive to the influence of path loss with a larger channel capacity, and a higher diversity gain and coding gain with a simple decoding algorithm will be achieved by employing the orthogonality of m-PPM in an optical-MIMO-based ultraviolet scattering channel.

  11. Displacement Ventilation by Different Types of Diffusers

    DEFF Research Database (Denmark)

    Nielsen, Peter V.; Hoff, Lars; Pedersen, Lars Germann

    The paper describes measuring results of the air movement from three different types of diffusers for displacement ventilation. Two of the diffusers are lowlevel wall mounted diffusers, one with a low and one with a high initial entrainment. The third diffuser is of the floor mounted type....

  12. A statistical method for estimating wood thermal diffusivity and probe geometry using in situ heat response curves from sap flow measurements.

    Science.gov (United States)

    Chen, Xingyuan; Miller, Gretchen R; Rubin, Yoram; Baldocchi, Dennis D

    2012-12-01

    The heat pulse method is widely used to measure water flux through plants; it works by using the speed at which a heat pulse is propagated through the system to infer the velocity of water through a porous medium. No systematic, non-destructive calibration procedure exists to determine the site-specific parameters necessary for calculating sap velocity, e.g., wood thermal diffusivity and probe spacing. Such parameter calibration is crucial to obtain the correct transpiration flux density from the sap flow measurements at the plant scale and subsequently to upscale tree-level water fluxes to canopy and landscape scales. The purpose of this study is to present a statistical framework for sampling and simultaneously estimating the tree's thermal diffusivity and probe spacing from in situ heat response curves collected by the implanted probes of a heat ratio measurement device. Conditioned on the time traces of wood temperature following a heat pulse, the parameters are inferred using a Bayesian inversion technique, based on the Markov chain Monte Carlo sampling method. The primary advantage of the proposed methodology is that it does not require knowledge of probe spacing or any further intrusive sampling of sapwood. The Bayesian framework also enables direct quantification of uncertainty in estimated sap flow velocity. Experiments using synthetic data show that repeated tests using the same apparatus are essential for obtaining reliable and accurate solutions. When applied to field conditions, these tests can be obtained in different seasons and can be automated using the existing data logging system. Empirical factors are introduced to account for the influence of non-ideal probe geometry on the estimation of heat pulse velocity, and are estimated in this study as well. The proposed methodology may be tested for its applicability to realistic field conditions, with an ultimate goal of calibrating heat ratio sap flow systems in practical applications.

  13. Sorption of Sr, Co and Zn on illite: Batch experiments and modelling including Co in-diffusion measurements on compacted samples

    Science.gov (United States)

    Montoya, V.; Baeyens, B.; Glaus, M. A.; Kupcik, T.; Marques Fernandes, M.; Van Laer, L.; Bruggeman, C.; Maes, N.; Schäfer, T.

    2018-02-01

    Experimental investigations on the uptake of divalent cations (Sr, Co and Zn) onto illite (Illite du Puy, Le-Puy-en-Velay, France) were carried out by three different international research groups (Institute for Nuclear Waste Disposal, KIT (Germany), Group Waste & Disposal, SCK-CEN, (Belgium) and Laboratory for Waste Management, PSI (Switzerland)) in the framework of the European FP7 CatClay project. The dependence of solid-liquid distribution ratios (Rd values) on pH at trace metal conditions (sorption edges) and on the metal ion concentration (sorption isotherms) was determined in dilute suspensions of homo-ionic Na-illite (Na-IdP) under controlled N2 atmosphere. The experimental results were modelled using the 2 Site Protolysis Non Electrostatic Surface Complexation and Cation Exchange (2SPNE SC/CE) sorption model. The sorption of Sr depends strongly on ionic strength, while a rather weak pH dependence is observed in a pH range between 3 and 11. The data were modelled with cation exchange reactions, taking into account competition with H, K, Ca, Mg and Al, and surface complexation on weak amphotheric edge sites at higher pH values. The sorption of Co on Na-IdP, however, is strongly pH dependent. Cation exchange on the planar sites and surface complexation on strong and weak amphoteric edge sites were used to describe the Co sorption data. Rd values for Co derived from in-diffusion measurements on compacted Na-IdP samples (bulk-dry density of 1700 kg m-3) between pH 5.0 and 9.0 are in good agreement with the batch sorption data. The equivalence of both approaches to measure sorption was thus confirmed for the present test system. In addition, the results highlight the importance of both major and minor surface species for the diffusive transport behaviour of strongly sorbing metal cations. While surface complexes at the edge sites determine largely the Rd value, the diffusive flux may be governed by those species bound to the planar sites, even at low fractional

  14. Isolation of Rhp-PSP, a member of YER057c/YjgF/UK114 protein family with antiviral properties, from the photosynthetic bacterium Rhodopseudomonas palustris strain JSC-3b.

    Science.gov (United States)

    Su, Pin; Feng, Tuizi; Zhou, Xuguo; Zhang, Songbai; Zhang, Yu; Cheng, Ju'e; Luo, Yuanhua; Peng, Jing; Zhang, Zhuo; Lu, Xiangyang; Zhang, Deyong; Liu, Yong

    2015-11-04

    Rhodopseudomonas palustris strain JSC-3b isolated from a water canal adjacent to a vegetable field produces a protein that was purified by bioactivity-guided fractionation based on ammonium sulfate precipitation, ion-exchange absorption and size exclusion. The protein was further identified as an endoribonuclease L-PSP (Liver-Perchloric acid-soluble protein) by shotgun mass spectrometry analysis and gene identification, and it is member of YER057c/YjgF/UK114 protein family. Herein, this protein is designated Rhp-PSP. Rhp-PSP exhibited significant inhibitory activities against tobacco mosaic virus (TMV) in vivo and in vitro. To our knowledge, this represents the first report on the antiviral activity of a protein of the YER057c/YjgF/UK114 family and also the first antiviral protein isolated from R. palustris. Our research provides insight into the potential of photosynthetic bacterial resources in biological control of plant virus diseases and sustainable agriculture.

  15. Low-speed pressure measurements using a luminescent coating system

    Science.gov (United States)

    Brown, Owen Clayton

    In this work, the history of the development of the Pressure Sensitive Paint (PSP) technique in both the United States and Russia is first discussed in detail. A review of the various PSP tests conducted to date is given. A thorough discussion of the physics and chemistry of luminescent coatings is provided. The processes of converting intensity signals in digital data values are described; image processing procedures used to remove noise sources and convert intensity data into pressure measurements are reviewed. A general uncertainty analysis of the technique is then conducted. A baseline series of low-speed tests at M NASCAR racing model at various drafting orientations.

  16. Construction, characterization and evaluation of the protective efficacy of the Streptococcus suis double mutant strain ΔSsPep/ΔSsPspC as a live vaccine candidate in mice.

    Science.gov (United States)

    Hu, Jin; You, Wujin; Wang, Bin; Hu, Xueying; Tan, Chen; Liu, Jinlin; Chen, Huanchun; Bei, Weicheng

    2015-01-01

    Streptococcus suis serotype 2 (S. suis 2) causes sepsis and meningitis in piglets and humans, and results in one of the most serious bacterial diseases affecting the production of commercial pigs around the world. Due to the failure of the current inactivated vaccine to protect against the disease, development of a new attenuated live vaccine against S. suis 2 by deleting essential virulence factors is urgently needed. We have previously reported the construction and characterization of an SsPep single gene deletion mutant strain ΔSsPep based on S. suis 2. Our previous results have shown that SsPep plays a critical role in the pathogenesis of S. suis 2. In this study, a precisely defined double-deletion mutant ΔSsPep/ΔSsPspC of S. suis 2 without antibiotic-resistance markers was constructed based on ΔSsPep, and the levels of virulence of the wild-type (WT) and ΔSsPep/ΔSsPspC were compared in a mouse experimental infection model. We demonstrated that the double mutant ΔSsPep/ΔSsPspC was less virulent than the WT, and could induce a noticeable antibody response. Analysis of IgG subclasses (IgG1 and IgG2a) indicated that both Th1 and Th2 responses were induced by ΔSsPep/ΔSsPspC, although the IgG2a (Th1) response predominated over the IgG1 (Th2) response. Moreover, ΔSsPep/ΔSsPspC could confer 90% protective efficacy against challenge with a lethal dose of fully virulent S. suis 2. Taken together, these data demonstrate that ΔSsPep/ΔSsPspC can be used as an effective live vaccine and provide a novel strategy against infection of S. suis 2. Copyright © 2014 Elsevier GmbH. All rights reserved.

  17. Diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kostorz, G. [Eidgenoessische Technische Hochschule, Angewandte Physik, Zurich (Switzerland)

    1996-12-31

    While Bragg scattering is characteristic for the average structure of crystals, static local deviations from the average lattice lead to diffuse elastic scattering around and between Bragg peaks. This scattering thus contains information on the occupation of lattice sites by different atomic species and on static local displacements, even in a macroscopically homogeneous crystalline sample. The various diffuse scattering effects, including those around the incident beam (small-angle scattering), are introduced and illustrated by typical results obtained for some Ni alloys. (author) 7 figs., 41 refs.

  18. Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurements of diffuse light.

    Science.gov (United States)

    Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G; Steenbergen, Wiendelt

    2007-12-01

    The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a turbid suspension of particles undergoing Brownian and translational motion. The path length resolution of this instrument is compared with a system using single mode fibers for illumination and detection. The optical path lengths are determined from the zero order moment of the phase modulation peak in the power spectrum. The weighted first moment, which is equal to the average Doppler shift, shows a linear response for different mean flow velocities within the physiological range.

  19. Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurements of diffuse light

    Science.gov (United States)

    Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G.; Steenbergen, Wiendelt

    2007-12-01

    The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a turbid suspension of particles undergoing Brownian and translational motion. The path length resolution of this instrument is compared with a system using single mode fibers for illumination and detection. The optical path lengths are determined from the zero order moment of the phase modulation peak in the power spectrum. The weighted first moment, which is equal to the average Doppler shift, shows a linear response for different mean flow velocities within the physiological range.

  20. Robust metamodel-based inverse estimation of bulk optical properties of turbid media from spatially resolved diffuse reflectance measurements.

    Science.gov (United States)

    Watté, Rodrigo; Aernouts, Ben; Van Beers, Robbe; Saeys, Wouter

    2015-10-19

    Estimation of the bulk optical properties of turbid samples from spatially resolved reflectance measurements remains challenging, as the relation between the bulk optical properties and the acquired spatially resolved reflectance profiles is influenced by wavelength-dependent properties of the measurement system. The resulting measurement noise is apparent in the estimation of the bulk optical properties. In this study, a constrained inverse metamodeling approach is proposed to overcome these problems. First, a metamodel has been trained on a set of intralipid phantoms covering a wide range of optical properties to link the acquired spatially resolved reflectance profiles to the respective combinations of bulk optical properties (absorption coefficient and reduced scattering coefficient). In this metamodel, the wavelength (500 - 1700 nm) is considered as a third input parameter for the model to account for the wavelength dependent effects introduced by the measurement system. Secondly, a smoothness constraint on the reduced scattering coefficient spectra was implemented in the iterative inverse estimation procedure to robustify it against measurement noise and increase the reliability of the obtained bulk absorption and reduced scattering coefficient spectra. As the estimated values in some regions may be more reliable than others, the difference between simulated and measured values as a function of the evaluated absorption and scattering coefficients was combined in a 2D cost function. This cost function was used as a weight in the fitting procedure to find the parameters of the µ(s)' function giving the lowest cost over all the wavelengths together. In accordance with previous research, an exponential function was considered to represent the µ(s)' spectra of intralipid phantoms. The fitting procedure also provides an absorption coefficient spectrum which is in accordance with the measurements and the estimated parameters of the exponential function. This

  1. Soot measurements by two angle scattering and extinction in an N 2 -diluted ethylene/air counterflow diffusion flame from 2 to 5 atm

    KAUST Repository

    Amin, Hafiz M.F.

    2016-06-27

    The soot formed in an N-diluted ethylene/air counterflow diffusion flame at elevated pressure was investigated using two angle light scattering/extinction technique. To provide a well-controlled pressurized environment for the flame, a novel pressure vessel was built with the required optical access. The soot parameters were measured along the centerline of the counterflow flame. These properties included soot volume fraction (f ), primary particle diameter (d ), population averaged radius of gyration (R ) and number density of primary particles (n ). The Rayleigh-Debye-Gans theory for Fractal Aggregates (RDG-FA) was used to retrieve these properties from scattering and extinction measurements. Soot volume fraction was measured via light extinction from 2 to 5atm while maintaining the same global strain rate at all pressures. Scattered light from soot particles was measured at 45° and 135° and primary particle diameter was calculated using scattering/extinction ratio and the radius of gyration was determined from the dissymmetry ratio. Soot volume fraction, primary particle diameter and radius of gyration all increased with pressure while the number density of primary particles decreased with increasing pressure.

  2. MD 2197: Experimental studies of Landau damping by means of Beam Transfer Function measurements in the presence of beam-beam interactions and diffusive mechanisms

    CERN Document Server

    Tambasco, Claudia; Barranco Garcia, Javier; Boccardi, Andrea; Buffat, Xavier; Bruce, Roderik; Gasior, Marek; Hostettler, Michi; Lefevre, Thibaut; Louro Alves, Diogo Miguel; Metral, Elias; Persson, Tobias Hakan Bjorn; Pieloni, Tatiana; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; CERN. Geneva. ATS Department

    2018-01-01

    Beam Transfer Function (BTF) measurements are direct measurement of the stability diagrams that define the stability threshold of coherent beam instabilities driven by the impedance. At the LHC, some coherent instabilities at flat top energy are still not fully understood and the BTF measurements provide a method to experimentally probe the Landau damping of the proton beams. The BTF response is sensitive to the particle distribution changes and contain information about the transverse tune spread in the beams. The BTF system has been installed in the LHC in the 2015 in order to investigate the Landau damping at different stages of the operational cycle, machine configurations (different octupole currents, crossing angles, tunes etc...) and in presence of beam-beam excited resonances that may provoke diffusion mechanisms with a consequence change of Landau damping. Past MDs showed some difficulties for the reconstruction of the stability diagram from BTF measurements and several improvements on the BTF sy...

  3. Adaptation of the "Dynamic Method" for measuring the specific respiration rate in oxygen transfer systems through diffusion membrane.

    Science.gov (United States)

    Pamboukian, Marilena Martins; Pereira, Carlos Augusto; Augusto, Elisabeth de Fatima Pires; Tonso, Aldo

    2011-12-01

    Monitoring the specific respiration rate (Q(O2)) is a valuable tool to evaluate cell growth and physiology. However, for low Q(O2) values the accuracy may depend on the measurement methodology, as it is the case in animal cell culture. The widely used "Dynamic Method" imposes serious difficulties concerning oxygen transfer cancellation, especially through membrane oxygenation. This paper presents an improved procedure to this method, through an automated control of the gas inlet composition that can minimize the residual oxygen transfer driving force during the Q(O2) measurement phase. The improved technique was applied to animal cell cultivation, particularly three recombinant S2 (Drosophila melanogaster) insect cell lines grown in a membrane aeration bioreactor. The average measurements of the proposed method reached 98% of stationary liquid phase balance method, taken as a reference, compared to 21% when the traditional method was used. Furthermore, this methodology does not require knowledge of the volumetric transfer coefficient k(L)a, which may vary during growth. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. A statistical method for estimating wood thermal diffusivity and probe geometry using in situ heat response curves from sap flow measurements

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xingyuan; Miller, Gretchen R.; Rubin, Yoram; Baldocchi, Dennis

    2012-09-13

    The heat pulse method is widely used to measure water flux through plants; it works by inferring the velocity of water through a porous medium from the speed at which a heat pulse is propagated through the system. No systematic, non-destructive calibration procedure exists to determine the site-specific parameters necessary for calculating sap velocity, e.g., wood thermal diffusivity and probe spacing. Such parameter calibration is crucial to obtain the correct transpiration flux density from the sap flow measurements at the plant scale; and consequently, to up-scale tree-level water fluxes to canopy and landscape scales. The purpose of this study is to present a statistical framework for estimating the wood thermal diffusivity and probe spacing simutaneously from in-situ heat response curves collected by the implanted probes of a heat ratio apparatus. Conditioned on the time traces of wood temperature following a heat pulse, the parameters are inferred using a Bayesian inversion technique, based on the Markov chain Monte Carlo sampling method. The primary advantage of the proposed methodology is that it does not require known probe spacing or any further intrusive sampling of sapwood. The Bayesian framework also enables direct quantification of uncertainty in estimated sap flow velocity. Experiments using synthetic data show that repeated tests using the same apparatus are essential to obtain reliable and accurate solutions. When applied to field conditions, these tests are conducted during different seasons and automated using the existing data logging system. The seasonality of wood thermal diffusivity is obtained as a by-product of the parameter estimation process, and it is shown to be affected by both moisture content and temperature. Empirical factors are often introduced to account for the influence of non-ideal probe geometry on the estimation of heat pulse velocity, and they are estimated in this study as well. The proposed methodology can be applied for

  5. Test of the diffusing-diffusivity mechanism using near-wall colloidal dynamics

    Science.gov (United States)

    Matse, Mpumelelo; Chubynsky, Mykyta V.; Bechhoefer, John

    2017-10-01

    The mechanism of diffusing diffusivity predicts that, in environments where the diffusivity changes gradually, the displacement distribution becomes non-Gaussian, even though the mean-square displacement grows linearly with time. Here, we report single-particle tracking measurements of the diffusion of colloidal spheres near a planar substrate. Because the local effective diffusivity is known, we have been able to carry out a direct test of this mechanism for diffusion in inhomogeneous media.

  6. Diffuse sound field: challenges and misconceptions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    Diffuse sound field is a popular, yet widely misused concept. Although its definition is relatively well established, acousticians use this term for different meanings. The diffuse sound field is defined by a uniform sound pressure distribution (spatial diffusion or homogeneity) and uniform...... incident intensity distribution (directional diffusion or isotropy). In practice, reverberation chambers are assumed to be acoustically diffuse, and important acoustic quantities measured in there, i.e., sound absorption, scattering, transmission, and power, etc. However, the measured quantities vary...... of mixing and diffuse sound field. Acousticians often refer diffuse reflections from surfaces to diffuseness in rooms, and vice versa. Subjective aspects of diffuseness have not been much investigated. Finally, ways to realize a diffuse sound field in a finite space are discussed....

  7. Diffuse sound field: challenges and misconceptions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    Diffuse sound field is a popular, yet widely misused concept. Although its definition is relatively well established, acousticians use this term for different meanings. The diffuse sound field is defined by a uniform sound pressure distribution (spatial diffusion or homogeneity) and uniform...... of mixing and diffuse sound field. Acousticians often refer diffuse reflections from surfaces to diffuseness in rooms, and vice versa. Subjective aspects of diffuseness have not been much investigated. Finally, ways to realize a diffuse sound field in a finite space are discussed....... incident intensity distribution (directional diffusion or isotropy). In practice, reverberation chambers are assumed to be acoustically diffuse, and important acoustic quantities measured in there, i.e., sound absorption, scattering, transmission, and power, etc. However, the measured quantities vary...

  8. Relativistic diffusion.

    Science.gov (United States)

    Haba, Z

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  9. Phase-conjugate resonant holographic interferometry applied to NH concentration measurements in a 2D diffusion flame

    Energy Technology Data Exchange (ETDEWEB)

    Tzannis, A.P.; Beaud, P.; Frey, H.M.; Gerber, T.; Mischler, B.; Radi, P.P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Resonant Holographic Interferometry is a method based on the anomalous dispersion of light having a frequency close to an electronic transition of a molecule. We propose a novel single-laser, two-colour setup for recording resonant holograms and apply it to 2D species concentration measurements. The second colour is generated by optical phase-conjugation from Stimulated Brillouin scattering in a cell. Phase-Conjugate Resonant Holographic Interferometry (PCRHI) is demonstrated in a 2D NH{sub 3}/O{sub 2} flame yielding interferograms that contain information on the NH radical distribution in the flame. Experimental results are quantified by applying a numerical computation of the Voigt profiles. (author) 1 fig., 3 refs.

  10. Modeling diffusion in colloidal suspensions by dynamical density functional theory using fundamental measure theory of hard spheres.

    Science.gov (United States)

    Stopper, Daniel; Marolt, Kevin; Roth, Roland; Hansen-Goos, Hendrik

    2015-08-01

    We study the dynamics of colloidal suspensions of hard spheres that are subject to Brownian motion in the overdamped limit. We obtain the time evolution of the self- and distinct parts of the van Hove function by means of dynamical density functional theory. The free-energy model for the hard-sphere fluid that we use is the very accurate White Bear II version of Rosenfeld's fundamental measure theory. However, in order to remove interactions within the self-part of the van Hove function, a nontrivial modification has to be applied to the free-energy functional. We compare our theoretical results with data that we obtain from dynamical Monte Carlo simulations, and we find that the latter are well described by our approach even for colloid packing fractions as large as 40%.

  11. Mean diffusivity of globus pallidus associated with verbal creativity measured by divergent thinking and creativity‐related temperaments in young healthy adults

    Science.gov (United States)

    Taki, Yasuyuki; Sekiguchi, Atsushi; Hashizume, Hiroshi; Nouchi, Rui; Sassa, Yuko; Kotozaki, Yuka; Miyauchi, Carlos Makoto; Yokoyama, Ryoichi; Iizuka, Kunio; Nakagawa, Seishu; Nagase, Tomomi; Kunitoki, Keiko; Kawashima, Ryuta

    2015-01-01

    Abstract Recent investigations revealed mean diffusivity (MD) in gray matter and white matter areas is correlated with individual cognitive differences in healthy subjects and show unique properties and sensitivity that other neuroimaging tools donot have. In this study, we tested the hypothesis that the MD in the dopaminergic system is associated with individual differences in verbal creativity measured by divergent thinking (VCDT) and novelty seeking based on prior studies suggesting associations between these and dopaminergic functions. We examined this issue in a large sample of right‐handed healthy young adults. We used analyses of MD and a psychological measure of VCDT, as well as personality measures of the Temperament and Character Inventory (TCI). Our results revealed associations between higher VCDT and lower MD in the bilateral globus pallidus. Furthermore, not only higher novelty seeking, but also lower harm avoidance, higher self‐directedness, and higher self‐transcendence were robustly associated with lower MD in the right globus pallidus, whereas higher persistence was associated with lower MD in the left globus pallidus. These personality variables were also associated with VCDT. The globus pallidus receives the dopaminergic input from the substantia nigra and plays a key role in motivation which is critically linked to dopamine. These results suggested the MD in the globus pallidus, underlie the association between VCDT and multiple personalities in TCI including novelty seeking. Hum Brain Mapp 36:1808–1827, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:25627674

  12. Mean diffusivity of globus pallidus associated with verbal creativity measured by divergent thinking and creativity-related temperaments in young healthy adults.

    Science.gov (United States)

    Takeuchi, Hikaru; Taki, Yasuyuki; Sekiguchi, Atsushi; Hashizume, Hiroshi; Nouchi, Rui; Sassa, Yuko; Kotozaki, Yuka; Miyauchi, Carlos Makoto; Yokoyama, Ryoichi; Iizuka, Kunio; Nakagawa, Seishu; Nagase, Tomomi; Kunitoki, Keiko; Kawashima, Ryuta

    2015-05-01

    Recent investigations revealed mean diffusivity (MD) in gray matter and white matter areas is correlated with individual cognitive differences in healthy subjects and show unique properties and sensitivity that other neuroimaging tools donot have. In this study, we tested the hypothesis that the MD in the dopaminergic system is associated with individual differences in verbal creativity measured by divergent thinking (VCDT) and novelty seeking based on prior studies suggesting associations between these and dopaminergic functions. We examined this issue in a large sample of right-handed healthy young adults. We used analyses of MD and a psychological measure of VCDT, as well as personality measures of the Temperament and Character Inventory (TCI). Our results revealed associations between higher VCDT and lower MD in the bilateral globus pallidus. Furthermore, not only higher novelty seeking, but also lower harm avoidance, higher self-directedness, and higher self-transcendence were robustly associated with lower MD in the right globus pallidus, whereas higher persistence was associated with lower MD in the left globus pallidus. These personality variables were also associated with VCDT. The globus pallidus receives the dopaminergic input from the substantia nigra and plays a key role in motivation which is critically linked to dopamine. These results suggested the MD in the globus pallidus, underlie the association between VCDT and multiple personalities in TCI including novelty seeking. © 2015 Wiley Periodicals, Inc.

  13. Lifetime, mobility, and diffusion of photoexcited carriers in ligand-exchanged lead selenide nanocrystal films measured by time-resolved terahertz spectroscopy.

    Science.gov (United States)

    Guglietta, Glenn W; Diroll, Benjamin T; Gaulding, E Ashley; Fordham, Julia L; Li, Siming; Murray, Christopher B; Baxter, Jason B

    2015-02-24

    Colloidal semiconductor nanocrystals have been used as building blocks for electronic and optoelectronic devices ranging from field-effect transistors to solar cells. Properties of the nanocrystal films depend sensitively on the choice of capping ligand to replace the insulating synthesis ligands. Thus far, ligands leading to the best performance in transistors result in poor solar cell performance, and vice versa. To gain insight into the nature of this dichotomy, we used time-resolved terahertz spectroscopy measurements to study the mobility and lifetime of PbSe nanocrystal films prepared with five common ligand-exchange reagents. Noncontact terahertz spectroscopy measurements of conductivity were corroborated by contacted van der Pauw measurements of the same samples. The films treated with different displacing ligands show more than an order of magnitude difference in the peak conductivities and a bifurcation of time dynamics. Inorganic chalcogenide ligand exchanges with sodium sulfide (Na2S) or ammonium thiocyanate (NH4SCN) show high mobilities but nearly complete decay of transient photocurrent in 1.4 ns. In contrast, ligand exchanges with 1,2-ethylenediamine (EDA), 1,2-ethanedithiol (EDT), and tetrabutylammonium iodide (TBAI) show lower mobilities but longer carrier lifetimes, resulting in longer diffusion lengths. This bifurcated behavior may explain the divergent performance of field-effect transistors and photovoltaics constructed from nanocrystal building blocks with different ligand exchanges.

  14. Diffuse light reflectance signals as potential indicators of loss of viability in brain tissue due to hypoxia: charge-coupled-device-based imaging and fiber-based measurement.

    Science.gov (United States)

    Kawauchi, Satoko; Nishidate, Izumi; Uozumi, Yoichi; Nawashiro, Hiroshi; Ashida, Hiroshi; Sato, Shunichi

    2013-01-01

    Brain tissue is highly vulnerable to ischemia/hypoxia, and real-time monitoring of its viability is important. By fiber-based measurements for rat brain, we previously observed a unique triphasic reflectance change (TRC) after a certain period of time after hypoxia. After TRC, rats could not be rescued, suggesting that TRC can be used as an indicator of loss of brain tissue viability. In this study, we investigated this diffuse-reflectance change due to hypoxia in three parts. First, we developed and validated a theoretical method to quantify changes in the absorption and reduced scattering coefficients involved in TRC. Second, we performed charge-coupled-device-based reflectance imaging of the rat brain during hypoxia followed by reoxygenation to examine spatiotemporal characteristics of the reflectance and its correlation with reversibility of brain tissue damage. Third, we made simultaneous imaging and fiber-based measurement of the reflectance for the rat to compare signals obtained by these two modalities. We observed a nontriphasic reflectance change by the imaging, and it was associated with brain tissue viability. We found that TRC measured by the fibers preceded the reflectance-signal change captured by the imaging. This time difference is attributable to the different observation depths in the brain with these two methods.

  15. The effect of hydrogen bonding on the diffusion of water in n-alkanes and n-alcohols measured with a novel single microdroplet method

    Science.gov (United States)

    Su, Jonathan T.; Duncan, P. Brent; Momaya, Amit; Jutila, Arimatti; Needham, David

    2010-01-01

    While the Stokes–Einstein (SE) equation predicts that the diffusion coefficient of a solute will be inversely proportional to the viscosity of the solvent, this relation is commonly known to fail for solutes, which are the same size or smaller than the solvent. Multiple researchers have reported that for small solutes, the diffusion coefficient is inversely proportional to the viscosity to a fractional power, and that solutes actually diffuse faster than SE predicts. For other solvent systems, attractive solute-solvent interactions, such as hydrogen bonding, are known to retard the diffusion of a solute. Some researchers have interpreted the slower diffusion due to hydrogen bonding as resulting from the effective diffusion of a larger complex of a solute and solvent molecules. We have developed and used a novel micropipette technique, which can form and hold a single microdroplet of water while it dissolves in a diffusion controlled environment into the solvent. This method has been used to examine the diffusion of water in both n-alkanes and n-alcohols. It was found that the polar solute water, diffusing in a solvent with which it cannot hydrogen bond, closely resembles small nonpolar solutes such as xenon and krypton diffusing in n-alkanes, with diffusion coefficients ranging from 12.5×10−5 cm2∕s for water in n-pentane to 1.15×10−5 cm2∕s for water in hexadecane. Diffusion coefficients were found to be inversely proportional to viscosity to a fractional power, and diffusion coefficients were faster than SE predicts. For water diffusing in a solvent (n-alcohols) with which it can hydrogen bond, diffusion coefficient values ranged from 1.75×10−5 cm2∕s in n-methanol to 0.364×10−5 cm2∕s in n-octanol, and diffusion was slower than an alkane of corresponding viscosity. We find no evidence for solute-solvent complex diffusion. Rather, it is possible that the small solute water may be retarded by relatively longer residence times (compared to non

  16. Bicarbonate diffusion through mucus.

    Science.gov (United States)

    Livingston, E H; Miller, J; Engel, E

    1995-09-01

    The mucus layer overlying duodenal epithelium maintains a pH gradient against high luminal acid concentrations. Despite these adverse conditions, epithelial surface pH remains close to neutrality. The exact nature of the gradient-forming barrier remains unknown. The barrier consists of mucus into which HCO3- is secreted. Quantification of the ability of HCO3- to establish and maintain the gradient depends on accurate measurement of this ion's diffusion coefficient through mucus. We describe new experimental and mathematical methods for diffusion measurement and report diffusion coefficients for HCO3- diffusion through saline, 5% mucin solutions, and rat duodenal mucus. The diffusion coefficients were 20.2 +/- 0.10, 3.02 +/- 0.31, and 1.81 +/- 0.12 x 10(-6) cm2/s, respectively. Modeling of the mucobicarbonate layer with this latter value suggests that for conditions of high luminal acid strength the neutralization of acid by HCO3- occurs just above the epithelial surface. Under these conditions the model predicts that fluid convection toward the lumen could be important in maintaining the pH gradient. In support of this hypothesis we were able to demonstrate a net luminal fluid flux of 5 microliters.min-1.cm-2 after perfusion of 0.15 N HCl in the rat duodenum.

  17. The apparent diffusion coefficient is strongly correlated with extracellular volume, a measure of myocardial fibrosis, and subclinical cardiomyopathy in patients with systemic lupus erythematosus.

    Science.gov (United States)

    Wu, Rui; An, Dong-Aolei; Hu, Jiani; Jiang, Meng; Guo, Qiang; Xu, Jian-Rong; Wu, Lian-Ming

    2017-01-01

    Background Extracellular volume (ECV) has been histologically validated as a non-invasive quantitative index of myocardial fibrosis that does not require the use of contrast, which is contraindicated in patients with renal insufficiency. Purpose To evaluate the correlation between the contrast-free apparent diffusion coefficient (ADC) and ECV, an index of fibrosis. Material and Methods Twenty-four patients with systemic lupus erythematosus (SLE), who were predominantly women (mean age = 36 ± 12 years) and 12 normal participants (mean age = 38 ± 10 years) underwent cardiac magnetic resonance (CMR) via 3.0 T MR with T1 mapping. Diffusion-weighted imaging (DWI) and late gadolinium-enhanced (LGE) imaging served as the reference standards with which CMR was compared. The mean ADC, native T1, and ECV were calculated for each patient, and the correlations among these parameters were analyzed. Results Both SLE LGE-positive (LGE+) and SLE LGE-negative (LGE-) participants had higher native T1 values, ECV, and ADC than normal controls ( P ECV (0.31 ± 0.02) and ADC (2.44 ± 0.32 × 10(-3 )mm(2)/s) than SLE LGE- participants ( p  0.05). ADC values were positively correlated with increased ECV (R(2 )= 0.62) and native T1 values (R(2 )= 0.28) in all participants. Conclusion ADC measurements are a suitable alternative to ECV that may be used to assess and quantify myocardial fibrosis in patients with SLE.

  18. Non-invasive measurements of hemoglobin + myoglobin, their oxygenation and NIR light pathlength in heart in vivo by diffuse reflectance spectroscopy

    Science.gov (United States)

    Gussakovsky, Eugene; Jilkina, Olga; Yang, Yanmin; Kupriyanov, Valery

    2009-02-01

    The existing non-invasive optical methods of the hemoglobin (Hb) and myoglobin (Mb) estimation in cardiac tissues imply knowledge of the light pathlength (L) when various modifications of Lambert-Beer law for either spectrophotometry or light diffuse reflectance is applied. For Hb and/or Mb quantification in tissue, a few invasive (biochemical) approaches were applied. For L (differential pathlength factor; DPF) determination in tissue, special optical methods were used. No approaches have been proposed to simultaneously and non-invasively determine Hb/Mb and L in cardiac or other muscle tissues. In the present study, the first derivative of the NIR diffuse reflectance spectrum is shown to be effective in simultaneous determination of Hb+Mb concentration (in mM) and L (in mm) in cardiac tissue in vivo. The results showed that measured in a few minutes in a normal pig heart in vivo the total Hb+Mb concentration was 0.9-1.2 mM of heme, tissue oxygen saturation parameter (OSP) was approximately 65%, and DPF at 700-965 nm was of 2.7-2.8. At the experimental ischemia, total [Hb+Mb] decreased by 25%, OSP reduced to zero, while DPF did not change. These results correlated with the previously published. The method may be applied during open-heart surgery, heart studies ex vivo or to any muscle tissue to continuously and non-invasively monitor the [Hb+Mb] content and oxygenation as well as L, which may reflect the changes in tissue structure.

  19. Global surface pressure measurements of static and dynamic stall on a wind turbine airfoil at low Reynolds number

    Science.gov (United States)

    Disotell, Kevin J.; Nikoueeyan, Pourya; Naughton, Jonathan W.; Gregory, James W.

    2016-05-01

    Recognizing the need for global surface measurement techniques to characterize the time-varying, three-dimensional loading encountered on rotating wind turbine blades, fast-responding pressure-sensitive paint (PSP) has been evaluated for resolving unsteady aerodynamic effects in incompressible flow. Results of a study aimed at demonstrating the laser-based, single-shot PSP technique on a low Reynolds number wind turbine airfoil in static and dynamic stall are reported. PSP was applied to the suction side of a Delft DU97-W-300 airfoil (maximum thickness-to-chord ratio of 30 %) at a chord Reynolds number of 225,000 in the University of Wyoming open-return wind tunnel. Static and dynamic stall behaviors are presented using instantaneous and phase-averaged global pressure maps. In particular, a three-dimensional pressure topology driven by a stall cell pattern is detected near the maximum lift condition on the steady airfoil. Trends in the PSP-measured pressure topology on the steady airfoil were confirmed using surface oil visualization. The dynamic stall case was characterized by a sinusoidal pitching motion with mean angle of 15.7°, amplitude of 11.2°, and reduced frequency of 0.106 based on semichord. PSP images were acquired at selected phase positions, capturing the breakdown of nominally two-dimensional flow near lift stall, development of post-stall suction near the trailing edge, and a highly three-dimensional topology as the flow reattaches. Structural patterns in the surface pressure topologies are considered from the analysis of the individual PSP snapshots, enabled by a laser-based excitation system that achieves sufficient signal-to-noise ratio in the single-shot images. The PSP results are found to be in general agreement with observations about the steady and unsteady stall characteristics expected for the airfoil.

  20. Diffusion in silicon isotope heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Silvestri, Hughes Howland [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    positively charged P species. Additionally, the temperature dependence of the diffusion coefficient of Si in Ge was measured over the temperature range of 550 C to 900 C using a buried Si layer in an epitaxially grown Ge layer.

  1. Refrigeration plants using carbon dioxide as refrigerant: measuring and modelling the solubility and diffusion of carbon dioxide in polymers used as sealing materials

    Energy Technology Data Exchange (ETDEWEB)

    von Solms, Nicolas; Kristensen, Jakob [Centre for Phase Equilibria and Separation Processes (IVC-SEP), Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2010-01-15

    Because of increased environmental pressure, there is currently a movement away from more traditional refrigerants such as HCFC's toward refrigerants with lower global warming potential such as carbon dioxide (CO{sub 2}). However, the use of CO{sub 2} as a refrigerant requires a refrigeration cycle with greater extremes of pressure, placing greater demands on the polymer materials used for seals and packing. In this work we have measured the solubility and diffusivity of gaseous CO{sub 2} in two polymers used as sealing materials in CO{sub 2} refrigeration plants. These are Hydrogenated Nitrile Butadiene Rubber (HNBR) and Ethylene Propylene Diene Monomer (EPDM) which are used in seals such as O-rings. The experiments were performed on a high-pressure microbalance. Solubility results were modelled using an equation of state for polymers (simplified PC-SAFT). The necessary polymer parameters were obtained using a previously published method. The measured results can be successfully correlated using simplified PC-SAFT. (author)

  2. Sodium polyacrylate as a binding agent in diffusive gradients in thin-films technique for the measurement of Cu2+ and Cd2+ in waters.

    Science.gov (United States)

    Fan, Hongtao; Sun, Ting; Li, Weijia; Sui, Dianpeng; Jin, Shuang; Lian, Xiaojing

    2009-10-15

    An aqueous solution containing sodium polyacrylate (PA, 0.0030M) was used in diffusive gradients in thin-films technique (DGT) to measure DGT-labile Cu(2+) and Cd(2+) concentrations. The DGT devices (PA DGT) were validated in four types of solutions, including synthetic river waters containing metal ions with or without complexing EDTA, natural river water (Hun River, Shenyang, China) spiked with Cu(2+) and Cd(2+), and an industrial wastewater (Shenyang, China). Results showed that only free metal ions were measured by PA DGT, recovery=98.79% for Cu(2+) and recovery=97.80% for Cd(2+) in solutions containing only free metal ions, recovery=51.02% for Cu(2+) and recovery=51.92% for Cd(2+) in solution with metal/EDTA molar ratio of 2:1 and recovery=0 in solutions with metal/EDTA molar ratio of 1:1 and 1:2. These indicated that the complexes of Cu-EDTA and Cd-EDTA were DGT-inert or not DGT-labile. The DGT performance in spiked river water (recovery=8.47% for Cu(2+) and recovery=27.48% for Cd(2+)) and in industrial wastewater (recovery=14.16% for Cd(2+)) were also investigated. Conditional stability constants (logK) of PA-Cu and PA-Cd complexes were determined as 6.98 and 5.61, respectively, indicating strong interaction between PA and the metals.

  3. Diffusion Tensor Fractional Anisotropy in the Superior Longitudinal Fasciculus Correlates with Functional Independence Measure Cognition Scores in Patients with Cerebral Infarction.

    Science.gov (United States)

    Koyama, Tetsuo; Domen, Kazuhisa

    2017-08-01

    This study aimed to determine the relationship between fiber tract degeneration measured by diffusion-tensor imaging (DTI) and outcome of patients after cerebral infarction. Fractional anisotropy (FA) maps were generated by DTI in patients 14-21 days after the first infarction and were analyzed by tract-based spatial statistics (TBSS). Mean FA values within the corticospinal tract (CST) and the superior longitudinal fasciculus (SLF) were extracted from individual TBSS data. Relationships between FA ratios (rFAs, lesioned to non-lesioned hemisphere) and outcomes assessed by Brunnstrom stage (BRS) and Functional Independence Measure (FIM) motor and cognition scores were examined using Spearman's rank correlation test. Forty patients (21 left and 19 right hemisphere lesions) were entered into an analytical database. BRS ranged from 1 to 6 (median, 5) for shoulder, elbow, or forearm; from 2 to 6 (median, 4.5) for hand or finger; and from 3 to 6 (median, 5) for lower extremity. FIM motor ranged from 51 to 91 (median, 79.5), and FIM cognition ranged from 16 to 35 (median, 29). rFA values in the CST ranged from .692 to 1.053 (median, .933), and those in the SLF ranged from .778 to 1.076 (median, .965). Mann-Whitney U test (P cognition scores (r = .409, P cognitive function and extremity function, respectively. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  4. Solute diffusivity in undisturbed soil

    DEFF Research Database (Denmark)

    Lægdsmand, Mette; Møldrup, Per; Schjønning, Per

    2012-01-01

    Solute diffusivity in soil plays a major role in many important processes with relation to plant growth and environmental issues. Soil solute diffusivity is affected by the volumetric water content as well as the morphological characteristics of water-filled pores. The solute diffusivity in intact...... tracers) for a better determination of the diffusivity. The diffusivity was higher in the below-till soil than the plowed soil at the same soil water matric potential due to higher water content but also due to higher continuity and lower tortuosity of the soil pores. We measured identical solute...... diffusivities independent of the tracer set used. We analyzed the whole data set using Archie's law and found a linear relation between Archie's exponent and the logarithm of the soil water matric suction in centimeters of water (pF). An analysis of seven data sets from the literature showed...

  5. SDSS-IV MaNGA: the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements

    Science.gov (United States)

    Zhang, Kai; Yan, Renbin; Bundy, Kevin; Bershady, Matthew; Haffner, L. Matthew; Walterbos, René; Maiolino, Roberto; Tremonti, Christy; Thomas, Daniel; Drory, Niv; Jones, Amy; Belfiore, Francesco; Sánchez, Sebastian F.; Diamond-Stanic, Aleksandar M.; Bizyaev, Dmitry; Nitschelm, Christian; Andrews, Brett; Brinkmann, Jon; Brownstein, Joel R.; Cheung, Edmond; Li, Cheng; Law, David R.; Roman Lopes, Alexandre; Oravetz, Daniel; Pan, Kaike; Storchi Bergmann, Thaisa; Simmons, Audrey

    2017-04-01

    Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG in star-forming galaxies impacts the measurements of emission-line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low ΣHα regions display enhanced [S II]/Hα, [N II]/Hα, [O II]/Hβ and [O I]/Hα. The gradients in these line ratios are determined by metallicity gradients and ΣHα. In line ratio diagnostic diagrams, contamination by DIG moves H II regions towards composite or low-ionization nuclear emission-line region (LI(N)ER)-like regions. A harder ionizing spectrum is needed to explain DIG line ratios. Leaky H II region models can only shift line ratios slightly relative to H II region models, and thus fail to explain the composite/LI(N)ER line ratios displayed by DIG. Our result favours ionization by evolved stars as a major ionization source for DIG with LI(N)ER-like emission. DIG can significantly bias the measurement of gas metallicity and metallicity gradients derived using strong-line methods. Metallicities derived using N2O2 are optimal because they exhibit the smallest bias and error. Using O3N2, R23, N2 = [N II]/Hα and N2S2Hα to derive metallicities introduces bias in the derived metallicity gradients as large as the gradient itself. The strong-line method of Blanc et al. (IZI hereafter) cannot be applied to DIG to get an accurate metallicity because it currently contains only H II region models that fail to describe the DIG.

  6. Models of diffuse solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Boland, John; Ridley, Barbara [Centre for Industrial and Applied Mathematics, University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, SA 5095 (Australia); Brown, Bruce [Department of Statistics and Applied Probability, National University of Singapore, Singapore 117546 (Singapore)

    2008-04-15

    For some locations both global and diffuse solar radiation are measured. However, for many locations, only global is measured, or inferred from satellite data. For modelling solar energy applications, the amount of radiation on a tilted surface is needed. Since only the direct component on a tilted surface can be calculated from trigonometry, we need to have diffuse on the horizontal available. There are regression relationships for estimating the diffuse on a tilted surface from diffuse on the horizontal. Models for estimating the diffuse radiation on the horizontal from horizontal global that have been developed in Europe or North America have proved to be inadequate for Australia [Spencer JW. A comparison of methods for estimating hourly diffuse solar radiation from global solar radiation. Sol Energy 1982; 29(1): 19-32]. Boland et al. [Modelling the diffuse fraction of global solar radiation on a horizontal surface. Environmetrics 2001; 12: 103-16] developed a validated model for Australian conditions. We detail our recent advances in developing the theoretical framework for the approach reported therein, particularly the use of the logistic function instead of piecewise linear or simple nonlinear functions. Additionally, we have also constructed a method, using quadratic programming, for identifying values that are likely to be erroneous. This allows us to eliminate outliers in diffuse radiation values, the data most prone to errors in measurement. (author)

  7. Apparent diffusion profile estimation from high angular resolution diffusion images

    Science.gov (United States)

    Descoteaux, Maxime; Angelino, Elaine; Fitzgibbons, Shaun; Deriche, Rachid

    2006-03-01

    High angular resolution diffusion imaging (HARDI) has recently been of great interest to characterize non-Gaussian diffusion process. In the white matter of the brain, this occurs when fiber bundles cross, kiss or diverge within the same voxel. One of the important goal is to better describe the apparent diffusion process in these multiple fiber regions, thus overcoming the limitations of classical diffusion tensor imaging (DTI). In this paper, we design the appropriate mathematical tools to describe noisy HARDI data. Using a meaningful modified spherical harmonics basis to capture the physical constraints of the problem, we propose a new regularization algorithm to estimate a smoother and closer diffusivity profile to the true diffusivities without noise. We exploit properties of the spherical harmonics to define a smoothing term based on the Laplace-Beltrami for functions defined on the unit sphere. An additional contribution of the paper is the derivation of the general transformation taking the spherical harmonics coefficients to the high order tensor independent elements. This allows the careful study of the state of the art high order anisotropy measures computed from either spherical harmonics or tensor coefficients. We analyze their ability to characterize the underlying diffusion process. We are able to recover voxels with isotropic, single fiber anisotropic and multiple fiber anisotropic diffusion. We test and validate the approach on diffusion profiles from synthetic data and from a biological rat phantom.

  8. Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS)