412 research outputs found

    A laboratory study to estimate pore geometric parameters of sandstones using complex conductivity and nuclear magnetic resonance for permeability prediction

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    We estimate parameters from the Katz and Thompson permeability model using laboratory complex electrical conductivity (CC) and nuclear magnetic resonance (NMR) data to build permeability models parameterized with geophysical measurements. We use the Katz and Thompson model based on the characteristic hydraulic length scale, determined from mercury injection capillary pressure estimates of pore throat size, and the intrinsic formation factor, determined from multi-salinity conductivity measurements, for this purpose. Two new permeability models are tested, one based on CC data and another that incorporates CC and NMR data. From measurements made on forty-five sandstone cores collected from fifteen different formations, we evaluate how well the CC relaxation time and the NMR transverse relaxation times compare to the characteristic hydraulic length scale and how well the formation factor estimated from CC parameters compares to the intrinsic formation factor. We find: (1) the NMR transverse relaxation time models the characteristic hydraulic length scale more accurately than the CC relaxation time (R2 of 0.69 and 0.39 and normalized root mean square errors (NRMSE) of 0.16 and 0.20, respectively); (2) the CC estimated formation factor is well correlated with the intrinsic formation factor (NRMSE=0.23). We demonstrate that that permeability estimates from the joint-NMR-CC model (NRMSE=0.13) compare favorably to estimates from the Katz and Thompson model (NRMSE=0.074). This model advances the capability of the Katz and Thompson model by employing parameters measureable in the field giving it the potential to more accurately estimate permeability using geophysical measurements than are currently possible

    Exploring the physiological correlates of chronic mild traumatic brain injury symptoms

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    We report on the results of a multimodal imaging study involving behavioral assessments, evoked and resting-state BOLD fMRI, and DTI in chronic mTBI subjects. We found that larger task-evoked BOLD activity in the MT+/LO region in extra-striate visual cortex correlated with mTBI and PTSD symptoms, especially light sensitivity. Moreover, higher FA values near the left optic radiation (OR) were associated with both light sensitivity and higher BOLD activity in the MT+/LO region. The MT+/LO region was localized as a region of abnormal functional connectivity with central white matter regions previously found to have abnormal physiological signals during visual eye movement tracking (Astafiev et al., 2015). We conclude that mTBI symptoms and light sensitivity may be related to excessive responsiveness of visual cortex to sensory stimuli. This abnormal sensitivity may be related to chronic remodeling of white matter visual pathways acutely injured

    Examples of trends in water management systems under influence of modern technologies

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    Dobivanje pouzdanih i pravovremenih informacija o trenutačnom i o budućem stanju voda omogućava učinkovito upravljanje vodnogospodarskim sustavima. U ovom se radu prikazuju prednosti i izazovi primjene naprednih tehnologija pri prikupljanju, obradi i integraciji podataka unutar nekoliko primjera sustava gospodarenja vodama. Pokazuje se kako napredne tehnologije imaju izraženu učinkovitost u preciznom praćenju različitih fenomena okoliša, u povećanju sigurnosti vodnih resursa i objekata te omogućavaju smanjenje potrošnje vode i energije uz povećanje kvalitete vode.Reliable and timely information about the current and future condition of water enables an efficient management of water management systems. Advantages and challenges of the use of modern technologies in the collection, analysis, and integration of data, are presented in this paper by means of several examples of water management systems. It is shown how advanced technologies demonstrate a pronounced efficiency in accurate monitoring of various environmental phenomena and in increasing safety of water resources and facilities, while also enabling low water and energy consumption, with simultaneous increase in water quality

    Review of empirical models for estimation of dune field characteristics

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    U radu je prikazan pregled sadašnjih spoznaja i pristup istraživanju dina proučavanjem neposrednih generatora fizikalnih procesa u koritu. On se temelji na mjerenjima brzine pokretnog dna koja karakterizira kretanje vučenog nanosa pomoću akustičnog strujomjera (ADCP-a). Utjecaj brzine pokretnog dna na morfodinamičke procese do danas je ostao neistražen.The paper presents an overview of the current state-of-the art and an approach to the study of dunes by analysing direct generators of physical processes in river beds. The approach is based on velocity measurements for mobile bed characterised by transport of bed load using the acoustic doppler current profiler (ADCP). The influence of mobile bed velocity on morphodynamic processes has remained unexplored to this day

    An overview of the applications of wavelet transform for discharge and suspended sediment analysis

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    Analiza i modeliranje vremenskih serija protoka i suspendiranog nanosa je vrlo važan zadatak u hidrologiji i gospodarenju vodama. Vremenske serije protoka i suspendiranog nanosa uvjetovane su složenim fizikalnim procesima i karakterizirane su nestacionarnošću. Valićna transformacija omogućava prikaz nestacionarnosti u vremensko-frekvencijskoj domeni, rastavljanje i rekonstrukciju serija te potiskivanje šuma u serijama, te time predstavlja moćan alat za analizu hidroloških vremenskih serija. U ovom radu je dan pregled primjene spomenutih prednosti valićne transformacije s fokusom na vremenske serije protoka i suspendiranog nanosa prikazan kroz: (i) viševremensku skalenu analizu varijabilnosti serija (ii) analizu trenda na više skala; (iii) predviđanje i prognoziranje serija hibridnim modelima crne-kutije baziranim na valićima te (iv) simulaciju sintetičkih serija potpomognutu valićnom transformacijom.Analysis and modelling of discharge and suspended sediment time series is of great importance in hydrology and water management. Discharge and suspended sediment time series are the result of complex physical processes and characterized by non-stationarity. Wavelet transform enables representation of non-stationarities in time-frequency domain, decomposition and reconstruction of series and de-noising of series, and therefore represents powerful tool for analysis of hydrological time series. Overview of mentioned wavelet transform advantages is given in this paper with focus on discharge and suspended sediment time series, presented through: (i) multi-temporal scale analysis of series variability; (ii) multi-scale trend analysis; (iii) prediction and forecasting of series with wavelet based hybrid black-box models, and (iv) wavelet-aided simulation of synthetic series

    Improvements in depressive symptoms following a brief relationship intervention

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    In the United States, 21 million adults are diagnosed with depression. Couple therapy effectively treats depression, however, couples encounter access barriers. The Relationship Checkup is an assessment and feedback intervention delivered in participants\u27 homes. The current study examines changes in relationship satisfaction and depressive symptoms, and moderators and mechanisms of change in a community sample (N = 85 couples). Changes in depressive symptoms and satisfaction, and the association between changes in satisfaction and depressive symptoms were examined with multilevel modeling. Depressive symptoms (Cohen\u27s d = 0.36) and satisfaction (d = 1.43) improved from baseline to 1-month follow-up, with greater declines in depression (d = 0.44) for those with more severe symptoms. Increases in satisfaction were associated with decreases in depressive symptoms (d = 0.23), and decreases in depressive symptoms were associated with increases in satisfaction (d = 0.33). Individuals with depression and relationship distress may be well served by this intervention. © 2023 The Authors. Journal of Marital and Family Therapy published by Wiley Periodicals LLC on behalf of American Association for Marriage and Family Therapy

    Pharmacologically relevant doses of valproate upregulate CD20 expression in three diffuse large B-cell lymphoma patients in vivo.

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    Epigenetic code modifications by histone deacetylase inhibitors (HDACi) have been proposed as potential new therapies for lymphoid malignancies. Diffuse large B-cell lymphoma (DLBCL) is the most common type of aggressive lymphoma for which standard first line treatment is the chemotherapy regimen CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) combined with the monoclonal anti-CD20 antibody rituximab (R-CHOP). The HDACi valproate, which has for long been utilized in anti-convulsive therapy, has been shown to sensitize to chemotherapy in vitro. Valproate upregulates expression of CD20 in lymphoma cell lines; therefore, 48 hour pre-treatment with valproate before first line R-CHOP in DLBCL stages II-IV is evaluated in the phase I clinical trial VALFRID; Valproate as First line therapy in combination with Rituximab and CHOP in Diffuse large B-cell lymphoma

    Anomalous solute transport in saturated porous media:linking transport model parameters to electrical and nuclear magnetic resonance properties

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    The advection-dispersion equation (ADE) fails to describe commonly observed non-Fickian solute transport in saturated porous media, necessitating the use of other models such as the dual-domain mass-transfer (DDMT) model. DDMT model parameters are commonly calibrated via curve fitting, providing little insight into the relation between effective parameters and physical properties of the medium. There is a clear need for material characterization techniques that can provide insight into the geometry and connectedness of pore spaces related to transport model parameters. Here, we consider proton nuclear magnetic resonance (NMR), direct-current (DC) resistivity, and complex conductivity (CC) measurements for this purpose, and assess these methods using glass beads as a control and two different samples of the zeolite clinoptilolite, a material that demonstrates non-Fickian transport due to intragranular porosity. We estimate DDMT parameters via calibration of a transport model to column-scale solute tracer tests, and compare NMR, DC resistivity, CC results, which reveal that grain size alone does not control transport properties and measured geophysical parameters; rather, volume and arrangement of the pore space play important roles. NMR cannot provide estimates of more-mobile and less-mobile pore volumes in the absence of tracer tests because these estimates depend critically on the selection of a material-dependent and flow-dependent cutoff time. Increased electrical connectedness from DC resistivity measurements are associated with greater mobile pore space determined from transport model calibration. CC was hypothesized to be related to length scales of mass transfer, but the CC response is unrelated to DDMT

    Clickers Can Promote Fact Retention But Impede Conceptual Understanding: The Effect of the Interaction Between Clicker Use and Pedagogy on Learning

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    Highlights Two experiments explored the role of clickers on factual and conceptual learning. One course emphasized fact retention and the other emphasized conceptual understanding. Factual and conceptual clicker questions enhanced only fact learning in the didactic course. Factual questions impaired conceptual learning in the problem-oriented course. Clicker effects are mediated by pedagogy, learning strategy, and prior knowledge
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