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Sample records for perfusion diffusion confusion

  1. Reduce Confusion about Diffusion.

    ERIC Educational Resources Information Center

    Hebrank, Mary R.

    1997-01-01

    Presents activities that allow students to explore the fundamental but poorly understood concept of diffusion by appealing to their kinesthetic senses first, then challenging their analytical skills as they try to deduce the mathematical principle involved. Presents a computer simulation of diffusion and discusses diffusion's limitations and…

  2. Demonstrating Diffusion: Why the Confusion?

    ERIC Educational Resources Information Center

    Panizzon, Debra Lee

    1998-01-01

    Examines the principles of diffusion and how it may be confused with convection. Suggests that educators may be misleading students and clouding their understanding of the process. Provides two contemporary examples to explain the process of diffusion and how it differs from convection. (Author/CCM)

  3. Living with Technology Diffusion Confusion.

    ERIC Educational Resources Information Center

    Isaak, Troy; Ward, John

    This paper is a report on the implementation of a project to diffuse technology throughout a teacher education program in elementary education at Millersville University (Pennsylvania). Rather than relying on a single technology course in a preservice program, students develop technology skills in a variety of courses in the education sequence and…

  4. Confusion

    MedlinePlus

    ... or drug intoxication Brain tumor Head trauma or head injury ( concussion ) Fever Fluid and electrolyte imbalance Illness in ... someone with diabetes Confusion came on after a head injury The person becomes unconscious at any time If ...

  5. Scintigraphic perfusion patterns in patients with diffuse lung disease

    SciTech Connect

    Newman, G.E.; Sullivan, D.C.; Gottschalk, A.; Putman, C.E.

    1982-04-01

    Perfusion scintigrams of 55 patients with radiographic evidence of diffuse lung disease were reviewed. Thirty-nine had acute and/or chronic changes caused by congestive heart failure, and 16 had diffuse reticulonodular disease. A normal or near-normal perfusion pattern was seen in 40/55 (73%), and this finding was equally common in the two groups. The authors conclude that perfusion scintigraphy is useful in excluding pulmonary embolism in patients with radiographic evidence of diffuse, symmetrical lung disease.

  6. Using Diffusion of Innovations Theory to implement the confusion assessment method for the intensive care unit.

    PubMed

    Bowen, Constance Mary; Stanton, Marietta; Manno, Martin

    2012-01-01

    Routine screening of mechanically ventilated patients for delirium is essential for prompt recognition and management; however, this represents a change in practice. Rogers' Diffusion of Innovations Theory can be useful as a strategy to facilitate adoption of a practice change. This case study describes the effectiveness of identifying barriers to a change in practice and developing strategies, specific to Rogers' innovation decision process, for implementing the Confusion Assessment Method for the intensive care unit. PMID:22367153

  7. Diffusion and perfusion MRI of the lung and mediastinum.

    PubMed

    Henzler, Thomas; Schmid-Bindert, Gerald; Schoenberg, Stefan O; Fink, Christian

    2010-12-01

    With ongoing technical improvements such as multichannel MRI, systems with powerful gradients as well as the development of innovative pulse sequence techniques implementing parallel imaging, MRI has now entered the stage of a radiation-free alternative to computed tomography (CT) for chest imaging in clinical practice. Whereas in the past MRI of the lung was focused on morphological aspects, current MRI techniques also enable functional imaging of the lung allowing for a comprehensive assessment of lung disease in a single MRI exam. Perfusion imaging can be used for the visualization of regional pulmonary perfusion in patients with different lung diseases such as lung cancer, chronic obstructive lung disease, pulmonary embolism or for the prediction of postoperative lung function in lung cancer patients. Over the past years diffusion-weighted MR imaging (DW-MRI) of the thorax has become feasible with a significant reduction of the acquisition time, thus minimizing artifacts from respiratory and cardiac motion. In chest imaging, DW-MRI has been mainly suggested for the characterization of lung cancer, lymph nodes and pulmonary metastases. In this review article recent MR perfusion and diffusion techniques of the lung and mediastinum as well as their clinical applications are reviewed. PMID:20627435

  8. Diffusion and Perfusion: The Keys to Fat Grafting

    PubMed Central

    Khouri, Roger K.; Khouri, Raoul-Emil R.; Lujan-Hernandez, Jorge R.; Khouri, Khalil R.; Lancerotto, Luca

    2014-01-01

    Background: Fat grafting is now widely used in plastic surgery. Long-term graft retention can be unpredictable. Fat grafts must obtain oxygen via diffusion until neovascularization occurs, so oxygen delivery may be the overarching variable in graft retention. Methods: We studied the peer-reviewed literature to determine which aspects of a fat graft and the microenvironment surrounding a fat graft affect oxygen delivery and created 3 models relating distinct variables to oxygen delivery and graft retention. Results: Our models confirm that thin microribbons of fat maximize oxygen transport when injected into a large, compliant, well-vascularized recipient site. The “Microribbon Model” predicts that, in a typical human, fat injections larger than 0.16 cm in radius will have a region of central necrosis. Our “Fluid Accommodation Model” predicts that once grafted tissues approach a critical interstitial fluid pressure of 9 mm Hg, any additional fluid will drastically increase interstitial fluid pressure and reduce capillary perfusion and oxygen delivery. Our “External Volume Expansion Effect Model” predicts the effect of vascular changes induced by preoperative external volume expansion that allow for greater volumes of fat to be successfully grafted. Conclusions: These models confirm that initial fat grafting survival is limited by oxygen diffusion. Preoperative expansion increases oxygen diffusion capacity allowing for additional graft retention. These models provide a scientific framework for testing the current fat grafting theories. PMID:25426403

  9. Contrast-enhanced diffuse optical tomography of brain perfusion in humans using ICG

    NASA Astrophysics Data System (ADS)

    Habermehl, Christina; Schmitz, Christoph; Steinbrink, Jens

    2012-02-01

    Regular monitoring of brain perfusion at the bedside in neurointensive care is desirable. Currently used imaging modalities are not suited for constant monitoring and often require a transport of the patient. Noninvasive near infrared spectroscopy (NIRS) in combination with an injection of a safe dye (indocyanine green, ICG) could serve as a quasi-continuous brain perfusion monitor. In this work, we evaluate prerequisites for the development of a brain perfusion monitor using continuous wave (cw) NIRS technique. We present results from a high-resolution diffuse optical tomography (HR-DOT) experiment in humans demonstrating the separation of signals from skin from the brain. This technique can help to monitor neurointensive care patients on a regular basis, detecting changes in cortical perfusion in time.

  10. Perfusion and diffusion MRI of glioblastoma progression in a four-year prospective temozolomide clinical trial

    SciTech Connect

    Leimgruber, Antoine; Ostermann, Sandrine; Yeon, Eun Jo; Buff, Evelyn; Maeder, Philippe P.; Stupp, Roger; Meuli, Reto A. . E-mail: Reto.Meuli@chuv.ch

    2006-03-01

    Purpose: This study was performed to determine the impact of perfusion and diffusion magnetic resonance imaging (MRI) sequences on patients during treatment of newly diagnosed glioblastoma. Special emphasis has been given to these imaging technologies as tools to potentially anticipate disease progression, as progression-free survival is frequently used as a surrogate endpoint. Methods and Materials: Forty-one patients from a phase II temolozomide clinical trial were included. During follow-up, images were integrated 21 to 28 days after radiochemotherapy and every 2 months thereafter. Assessment of scans included measurement of size of lesion on T1 contrast-enhanced, T2, diffusion, and perfusion images, as well as mass effect. Classical criteria on tumor size variation and clinical parameters were used to set disease progression date. Results: A total of 311 MRI examinations were reviewed. At disease progression (32 patients), a multivariate Cox regression determined 2 significant survival parameters: T1 largest diameter (p < 0.02) and T2 size variation (p < 0.05), whereas perfusion and diffusion were not significant. Conclusion: Perfusion and diffusion techniques cannot be used to anticipate tumor progression. Decision making at disease progression is critical, and classical T1 and T2 imaging remain the gold standard. Specifically, a T1 contrast enhancement over 3 cm in largest diameter together with an increased T2 hypersignal is a marker of inferior prognosis.

  11. Phase-based metamorphosis of diffusion lesion in relation to perfusion values in acute ischemic stroke.

    PubMed

    Rekik, Islem; Allassonnière, Stéphanie; Luby, Marie; Carpenter, Trevor K; Wardlaw, Joanna M

    2015-01-01

    Examining the dynamics of stroke ischemia is limited by the standard use of 2D-volume or voxel-based analysis techniques. Recently developed spatiotemporal models such as the 4D metamorphosis model showed promise for capturing ischemia dynamics. We used a 4D metamorphosis model to evaluate acute ischemic stroke lesion morphology from the acute diffusion-weighted imaging (DWI) to final T2-weighted imaging (T2-w). In 20 representative patients, we metamorphosed the acute lesion to subacute lesion to final infarct. From the DWI lesion deformation maps we identified dynamic lesion areas and examined their association with perfusion values inside and around the lesion edges, blinded to reperfusion status. We then tested the model in ten independent patients from the STroke Imaging Repository (STIR). Perfusion values varied widely between and within patients, and were similar in contracting and expanding DWI areas in many patients in both datasets. In 25% of patients, the perfusion values were higher in DWI-contracting than DWI-expanding areas. A similar wide range of perfusion values and ongoing expansion and contraction of the DWI lesion were seen subacutely. There was more DWI contraction and less expansion in patients who received thrombolysis, although with widely ranging perfusion values that did not differ. 4D metamorphosis modeling shows promise as a method to improve use of multimodal imaging to understand the evolution of acute ischemic tissue towards its fate. PMID:26288755

  12. Diffusion-perfusion relationships in skeletal muscle: models and experimental evidence from inert gas washout.

    PubMed

    Piiper, J; Meyer, M

    1984-01-01

    In order to study the dependence of blood-tissue gas exchange upon diffusion, the simultaneous washout of two inert gases of differing diffusivity was investigated in isolated-perfused dog gastrocnemius preparations. The muscles were equilibrated with CH4 and SF6 via arterial blood. The washout kinetics were determined from venous blood samples analyzed by gas chromatography. The results revealed the following features: The washout of the test gases was pronouncedly multi-exponential, and could be described by three exponential components when analyzed to 5% of the initial value. The non-exponential washout was attributed to unequal distribution of capillary blood flow to tissue volume. The mean ratio of washout rate constants CH4/SF6 was within 1.10-1.25 and was even smaller than the ratio expected for pure perfusion limitation (1.46). Therefore, no evidence for effective tissue-blood diffusion limitation was obtained. The observed washout rate constant ratio could be explained by a model with veno-arterial back diffusion which more strongly retards washout kinetics of the better diffusible gas (CH4) as compared to the less diffusible gas (SF6). PMID:6731103

  13. Diffusing capacities and ventilation: perfusion ratios in patients with the clinical syndrome of alveolar capillary block

    PubMed Central

    Arndt, Hartmut; King, Thomas K. C.; Briscoe, William A.

    1970-01-01

    Studies were performed on 10 patients with the clinical syndrome of alveolar capillary block while each patient was breathing four different inspired oxygen mixtures. The data were interpreted using the principle of the Bohr integral isopleth with which alveolar oxygen tension in the differently ventilated parts of the lung can initially be treated as unknown. It is then possible to determine the distribution of ventilation, of perfusion, of diffusing capacity, of lung volume, and of alveolar and end capillary blood oxygen tension in the variously functioning parts of the lung. In two patients shunts were the major factor interfering with oxygen transfer. In four others inequalities in ventilation: perfusion ratios and in diffusing capacity in different parts of the lung were the factors interfering with oxygen transfer. In four more patients ventilation: perfusion ratios were the same throughout the lung, the only disturbance of oxygen transfer being in the total diffusing capacity or in its distribution between the different parts of the lung. PMID:5411791

  14. Validation of diffuse correlation spectroscopy for muscle blood flow with concurrent arterial spin labeled perfusion MRI

    NASA Astrophysics Data System (ADS)

    Yu, Guoqiang; Floyd, Thomas F.; Durduran, Turgut; Zhou, Chao; Wang, Jiongjiong; Detre, John A.; Yodh, Arjun G.

    2007-02-01

    Calf blood flow was measured simultaneously in healthy human subjects (n = 7) during cuff inflation and deflation using near-infrared diffuse correlation spectroscopy (DCS) and arterial spin labeled perfusion MRI (ASL-MRI). The DCS and ASL-MRI data exhibited highly correlated absolute and relative dynamic flow responses in each individual (p < 0.001). Peak flow variations during hyperemia were also significantly correlated, though more for relative (p = 0.003) than absolute (p = 0.016) flow. Repeated measurement variation was less than 8% for both modalities. The results provide much needed quantitative blood flow validation of the diffuse optical correlation method in humans.

  15. Comparison of stroke infarction between CT perfusion and diffusion weighted imaging: preliminary results

    NASA Astrophysics Data System (ADS)

    Abd. Rahni, Ashrani Aizzuddin; Arka, Israna Hossain; Chellappan, Kalaivani; Mukari, Shahizon Azura; Law, Zhe Kang; Sahathevan, Ramesh

    2016-03-01

    In this paper we present preliminary results of comparison of automatic segmentations of the infarct core, between that obtained from CT perfusion (based on time to peak parameter) and diffusion weighted imaging (DWI). For each patient, the two imaging volumes were automatically co-registered to a common frame of reference based on an acquired CT angiography image. The accuracy of image registration is measured by the overlap of the segmented brain from both images (CT perfusion and DWI), measured within their common field of view. Due to the limitations of the study, DWI was acquired as a follow up scan up to a week after initial CT based imaging. However, we found significant overlap of the segmented brain (Jaccard indices of approximately 0.8) and the percentage of infarcted brain tissue from the two modalities were still fairly highly correlated (correlation coefficient of approximately 0.9). The results are promising with more data needed in future for clinical inference.

  16. Multiparametric Characterization of Grade 2 Glioma Subtypes Using Magnetic Resonance Spectroscopic, Perfusion, and Diffusion Imaging1

    PubMed Central

    Bian, Wei; Khayal, Inas S; Lupo, Janine M; McGue, Colleen; Vandenberg, Scott; Lamborn, Kathleen R; Chang, Susan M; Cha, Soonmee; Nelson, Sarah J

    2009-01-01

    BACKGROUND AND PURPOSE: The purpose of this study was to derive quantitative parameters from magnetic resonance (MR) spectroscopic, perfusion, and diffusion imaging of grade 2 gliomas according to the World Health Organization and to investigate how these multiple imaging modalities can contribute to evaluating their histologic subtypes and spatial characteristics. MATERIALS AND METHODS: MR spectroscopic, perfusion, and diffusion images from 56 patients with newly diagnosed grade 2 glioma (24 oligodendrogliomas, 18 astrocytomas, and 14 oligoastrocytomas) were retrospectively studied. Metabolite intensities, relative cerebral blood volume (rCBV), and apparent diffusion coefficient (ADC) were statistically evaluated. RESULTS: The 75th percentile rCBV and median ADC were significantly different between oligodendrogliomas and astrocytomas (P < .0001) and between oligodendrogliomas and oligoastrocytomas (P < .001). Logistic regression analysis identified both 75th percentile rCBV and median ADC as significant variables in the differentiation of oligodendrogliomas from astrocytomas and oligoastrocytomas. Group differences in metabolite intensities were not significant, but there was a much larger variation in the volumes and maximum values of metabolic abnormalities for patients with oligodendroglioma compared with the other tumor subtypes. CONCLUSIONS: Perfusion and diffusion imaging provide quantitative MR parameters that can help to differentiate grade 2 oligodendrogliomas from grade 2 astrocytomas and oligoastrocytomas. The large variations in the magnitude and spatial extent of the metabolic lesions between patients and the fact that their values are not correlated with the other imaging parameters indicate that MR spectroscopic imaging may provide complementary information that is helpful in targeting therapy, evaluating residual disease, and assessing response to therapy. PMID:19956389

  17. Methylene blue treatment delays progression of perfusion-diffusion mismatch to infarct in permanent ischemic stroke

    PubMed Central

    Rodriguez, Pavel; Jiang, Zhao; Huang, Shiliang; Shen, Qiang; Duong, Timothy Q

    2016-01-01

    Stroke is a leading cause of morbidity and mortality in the world. Low-dose methylene blue (MB), which has been used safely to treat methemoglobinemia and cyanide poisoning in humans, has energy enhancing and antioxidant properties. We tested the hypothesis that methylene blue treatment delays progression of at-risk tissue (ca. perfusion-diffusion mismatch) to infarct in permanent middle cerebral artery occlusion in rats at two MB treatment doses. Serial MRI was used to evaluate MB treatment efficacy. The major findings were: (i) MB significantly prolonged the perfusion-diffusion mismatch, (ii) MB mildly increased the CBF in the hypoperfused tissue, (iii) MB did not change the final infarct volume in permanent ischemic stroke, and (iv) there were no dose-dependent effects on mismatch progression for the 1 and 3mg/kg doses studied. This neuroprotective effect is likely the result of sustained ATP production and increased CBF to tissue at risk. This work has the potential to readily lead to clinical stroke trials given MB's excellent safety profile. PMID:25218555

  18. Prognostic value of combined visualization of MR diffusion and perfusion maps in glioblastoma.

    PubMed

    Deike, Katerina; Wiestler, Benedikt; Graf, Markus; Reimer, Caroline; Floca, Ralf O; Bäumer, Philipp; Kickingereder, Philipp; Heiland, Sabine; Schlemmer, Heinz-Peter; Wick, Wolfgang; Bendszus, Martin; Radbruch, Alexander

    2016-02-01

    We analyzed whether the combined visualization of decreased apparent diffusion coefficient (ADC) values and increased cerebral blood volume (CBV) in perfusion imaging can identify prognosis-related growth patterns in patients with newly diagnosed glioblastoma. Sixty-five consecutive patients were examined with diffusion and dynamic susceptibility-weighted contrast-enhanced perfusion weighted MRI. ADC and CBV maps were co-registered on the T1-w image and a region of interest (ROI) was manually delineated encompassing the enhancing lesion. Within this ROI pixels with ADC values the 70th percentile (CBVmax) and the intersection of pixels with ADCmin and CBVmax were automatically calculated and visualized. Initially, all tumors with a mean intersection greater than the upper quartile of the normally distributed mean intersection of all patients were subsumed to the first growth pattern termed big intersection (BI). Subsequently, the remaining tumors' growth patterns were categorized depending on the qualitative representation of ADCmin, CBVmax and their intersection. Log-rank test exposed a significantly longer overall survival of BI (n = 16) compared to non-BI group (n = 49) (p = 0.0057). Thirty-one, four and 14 patients of the non-BI group were classified as predominant ADC-, CBV- and mixed growth group, respectively. In a multivariate Cox regression model, the BI-, CBV- and mixed groups had significantly lower adjusted hazard ratios (p-value, α(Bonferroni) < 0.006) when compared to the reference group ADC: 0.29 (0.0027), 0.11 (0.038) and 0.33 (0.0059). Our study provides evidence that the combination of diffusion and perfusion imaging allows visualization of different glioblastoma growth patterns that are associated with prognosis. A possible biological hypothesis for this finding could be the interpretation of the ADCmin fraction as the invasion-front of tumor cells while the CBVmax fraction might represent

  19. Comparison of Perfusion- and Diffusion-weighted Imaging Parameters in Brain Tumor Studies Processed Using Different Software Platforms

    PubMed Central

    Milchenko, Mikhail V.; Rajderkar, Dhanashree; LaMontagne, Pamela; Massoumzadeh, Parinaz; Bogdasarian, Ronald; Schweitzer, Gordon; Benzinger, Tammie; Marcus, Dan; Shimony, Joshua S.; Fouke, Sarah Jost

    2015-01-01

    Rationale and Objectives To compare quantitative imaging parameter measures from diffusion- and perfusion-weighted imaging magnetic resonance imaging (MRI) sequences in subjects with brain tumors that have been processed with different software platforms. Materials and Methods Scans from 20 subjects with primary brain tumors were selected from the Comprehensive Neuro-oncology Data Repository at Washington University School of Medicine (WUSM) and the Swedish Neuroscience Institute. MR images were coregistered, and each subject's data set was processed by three software packages: 1) vendor-specific scanner software, 2) research software developed at WUSM, and 3) a commercially available, Food and Drug Administration–approved, processing platform (Nordic Ice). Regions of interest (ROIs) were chosen within the brain tumor and normal nontumor tissue. The results obtained using these methods were compared. Results For diffusion parameters, including mean diffusivity and fractional anisotropy, concordance was high when comparing different processing methods. For perfusion-imaging parameters, a significant variance in cerebral blood volume, cerebral blood flow, and mean transit time (MTT) values was seen when comparing the same raw data processed using different software platforms. Correlation was better with larger ROIs (radii ≥ 5 mm). Greatest variance was observed in MTT. Conclusions Diffusion parameter values were consistent across different software processing platforms. Perfusion parameter values were more variable and were influenced by the software used. Variation in the MTT was especially large suggesting that MTT estimation may be unreliable in tumor tissues using current MRI perfusion methods. PMID:25088833

  20. Temporal Evolution of Ischemic Lesions in Nonhuman Primates: A Diffusion and Perfusion MRI Study

    PubMed Central

    Zhang, Xiaodong; Tong, Frank; Li, Chun-Xia; Yan, Yumei; Kempf, Doty; Nair, Govind; Wang, Silun; Muly, E. Chris; Zola, Stuart; Howell, Leonard

    2015-01-01

    Background and Purpose Diffusion-weighted imaging (DWI) and perfusion MRI were used to examine the spatiotemporal evolution of stroke lesions in adult macaques with ischemic occlusion. Methods Permanent MCA occlusion was induced with silk sutures through an interventional approach via the femoral artery in adult rhesus monkeys (n = 8, 10–21 years old). The stroke lesions were examined with high-resolution DWI and perfusion MRI, and T2-weighted imaging (T2W) on a clinical 3T scanner at 1–6, 48, and 96 hours post occlusion and validated with H&E staining. Results The stroke infarct evolved via a natural logarithmic pattern with the mean infarct growth rate = 1.38 ± 1.32 ml per logarithmic time scale (hours) (n = 7) in the hyperacute phase (1–6 hours). The mean infarct volume after 6 hours post occlusion was 3.6±2.8 ml (n = 7, by DWI) and increased to 3.9±2.9 ml (n = 5, by T2W) after 48 hours, and to 4.7±2.2ml (n = 3, by T2W) after 96 hours post occlusion. The infarct volumes predicted by the natural logarithmic function were correlated significantly with the T2W-derived lesion volumes (n = 5, r = 0.92, p = 0.01) at 48 hours post occlusion. The final infarct volumes derived from T2W were correlated significantly with those from H&E staining (r = 0.999, p < 0.0001, n = 4). In addition, the diffusion-perfusion mismatch was visible generally at 6 hours but nearly diminished at 48 hours post occlusion. Conclusion The infarct evolution follows a natural logarithmic pattern in the hyperacute phase of stroke. The logarithmic pattern of evolution could last up to 48 hours after stroke onset and may be used to predict the infarct volume growth during the acute phase of ischemic stroke. The nonhuman primate model, MRI protocols, and post data processing strategy may provide an excellent platform for characterizing the evolution of acute stroke lesion in mechanistic studies and therapeutic interventions of stroke disease. PMID:25659092

  1. Alveolar ventilation to perfusion heterogeneity and diffusion impairment in a mathematical model of gas exchange

    NASA Technical Reports Server (NTRS)

    Vidal Melo, M. F.; Loeppky, J. A.; Caprihan, A.; Luft, U. C.

    1993-01-01

    This study describes a two-compartment model of pulmonary gas exchange in which alveolar ventilation to perfusion (VA/Q) heterogeneity and impairment of pulmonary diffusing capacity (D) are simultaneously taken into account. The mathematical model uses as input data measurements usually obtained in the lung function laboratory. It consists of two compartments and an anatomical shunt. Each compartment receives fractions of alveolar ventilation and blood flow. Mass balance equations and integration of Fick's law of diffusion are used to compute alveolar and blood O2 and CO2 values compatible with input O2 uptake and CO2 elimination. Two applications are presented. The first is a method to partition O2 and CO2 alveolar-arterial gradients into VA/Q and D components. The technique is evaluated in data of patients with chronic obstructive pulmonary disease (COPD). The second is a theoretical analysis of the effects of blood flow variation in alveolar and blood O2 partial pressures. The results show the importance of simultaneous consideration of D to estimate VA/Q heterogeneity in patients with diffusion impairment. This factor plays an increasing role in gas alveolar-arterial gradients as severity of COPD increases. Association of VA/Q heterogeneity and D may produce an increase of O2 arterial pressure with decreasing QT which would not be observed if only D were considered. We conclude that the presented computer model is a useful tool for description and interpretation of data from COPD patients and for performing theoretical analysis of variables involved in the gas exchange process.

  2. Analytical estimation of ultrasound properties, thermal diffusivity, and perfusion using magnetic resonance-guided focused ultrasound temperature data

    NASA Astrophysics Data System (ADS)

    Dillon, C. R.; Borasi, G.; Payne, A.

    2016-01-01

    For thermal modeling to play a significant role in treatment planning, monitoring, and control of magnetic resonance-guided focused ultrasound (MRgFUS) thermal therapies, accurate knowledge of ultrasound and thermal properties is essential. This study develops a new analytical solution for the temperature change observed in MRgFUS which can be used with experimental MR temperature data to provide estimates of the ultrasound initial heating rate, Gaussian beam variance, tissue thermal diffusivity, and Pennes perfusion parameter. Simulations demonstrate that this technique provides accurate and robust property estimates that are independent of the beam size, thermal diffusivity, and perfusion levels in the presence of realistic MR noise. The technique is also demonstrated in vivo using MRgFUS heating data in rabbit back muscle. Errors in property estimates are kept less than 5% by applying a third order Taylor series approximation of the perfusion term and ensuring the ratio of the fitting time (the duration of experimental data utilized for optimization) to the perfusion time constant remains less than one.

  3. Analytical estimation of ultrasound properties, thermal diffusivity, and perfusion using magnetic resonance-guided focused ultrasound temperature data.

    PubMed

    Dillon, C R; Borasi, G; Payne, A

    2016-01-21

    For thermal modeling to play a significant role in treatment planning, monitoring, and control of magnetic resonance-guided focused ultrasound (MRgFUS) thermal therapies, accurate knowledge of ultrasound and thermal properties is essential. This study develops a new analytical solution for the temperature change observed in MRgFUS which can be used with experimental MR temperature data to provide estimates of the ultrasound initial heating rate, Gaussian beam variance, tissue thermal diffusivity, and Pennes perfusion parameter. Simulations demonstrate that this technique provides accurate and robust property estimates that are independent of the beam size, thermal diffusivity, and perfusion levels in the presence of realistic MR noise. The technique is also demonstrated in vivo using MRgFUS heating data in rabbit back muscle. Errors in property estimates are kept less than 5% by applying a third order Taylor series approximation of the perfusion term and ensuring the ratio of the fitting time (the duration of experimental data utilized for optimization) to the perfusion time constant remains less than one. PMID:26741344

  4. Perfusion and diffusion sensitive 13C stimulated-echo MRSI for metabolic imaging of cancer.

    PubMed

    Larson, Peder E Z; Hurd, Ralph E; Kerr, Adam B; Pauly, John M; Bok, Robert A; Kurhanewicz, John; Vigneron, Daniel B

    2013-06-01

    Metabolic imaging with hyperpolarized [1-(13)C]-pyruvate can rapidly probe tissue metabolic profiles in vivo and has been shown to provide cancer imaging biomarkers for tumor detection, progression, and response to therapy. This technique uses a bolus injection followed by imaging within 1-2 minutes. The observed metabolites include vascular components and their generation is also influenced by cellular transport. These factors complicate image interpretation, especially since [1-(13)C]lactate, a metabolic product that is a biomarker of cancer, is also produced by red blood cells. It would be valuable to understand the distribution of metabolites between the vasculature, interstitial space, and intracellular compartments. The purpose of this study was to better understand this compartmentalization by using a perfusion and diffusion-sensitive stimulated-echo acquisition mode (STEAM) MRSI acquisition method tailored to hyperpolarized substrates. Our results in mouse models showed that among metabolites, the injected substrate (13)C-pyruvate had the largest vascular fraction overall while (13)C-alanine had the smallest vascular fraction. We observed a larger vascular fraction of pyruvate and lactate in the kidneys and liver when compared to back muscle and prostate tumor tissue. Our data suggests that (13)C-lactate in prostate tumor tissue voxels was the most abundant labeled metabolite intracellularly. This was shown in STEAM images that highlighted abnormal cancer cell metabolism and suppressed vascular (13)C metabolite signals. PMID:23260391

  5. Production of Xylella fastidiosa diffusible signal factor in transgenic grape causes pathogen confusion and reduction in severity of Pierce's disease.

    PubMed

    Lindow, Steven; Newman, Karyn; Chatterjee, Subhadeep; Baccari, Clelia; Lavarone, Anthony T; Ionescu, Michael

    2014-03-01

    The rpfF gene from Xylella fastidiosa, encoding the synthase for diffusible signal factor (DSF), was expressed in 'Freedom' grape to reduce the pathogen's growth and mobility within the plant. Symptoms in such plants were restricted to near the point of inoculation and incidence of disease was two- to fivefold lower than in the parental line. Both the longitudinal and lateral movement of X. fastidiosa in the xylem was also much lower. DSF was detected in both leaves and xylem sap of RpfF-expressing plants using biological sensors, and both 2-Z-tetradecenoic acid, previously identified as a component of X. fastidiosa DSF, and cis-11-methyl-2-dodecenoic acid were detected in xylem sap using electrospray ionization mass spectrometry. A higher proportion of X. fastidiosa cells adhered to xylem vessels of the RpfF-expressing line than parental 'Freedom' plants, reflecting a higher adhesiveness of the pathogen in the presence of DSF. Disease incidence in RpfF-expressing plants in field trials in which plants were either mechanically inoculated with X. fastidiosa or subjected to natural inoculation by sharpshooter vectors was two- to fourfold lower in than that of the parental line. The number of symptomatic leaves on infected shoots was reduced proportionally more than the incidence of infection, reflecting a decreased ability of X. fastidiosa to move within DSF-producing plants. PMID:24499029

  6. A practical assessment of magnetic resonance diffusion-perfusion mismatch in acute stroke: observer variation and outcome.

    PubMed

    Kane, I; Hand, P J; Rivers, C; Armitage, P; Bastin, M E; Lindley, R; Dennis, M; Wardlaw, J M

    2009-11-01

    MR diffusion/perfusion mismatch may help identify patients for acute stroke treatment, but mixed results from clinical trials suggest that further evaluation of the mismatch concept is required. To work effectively, mismatch should predict prognosis on arrival at hospital. We assessed mismatch duration and associations with functional outcome in acute stroke. We recruited consecutive patients with acute stroke, recorded baseline clinical variables, performed MR diffusion and perfusion imaging and assessed 3-month functional outcome. We assessed practicalities, agreement between mismatch on mean transit time (MTT) or cerebral blood flow (CBF) maps, visually and with lesion volume, and the relationship of each to functional outcome. Of 82 patients starting imaging, 14 (17%) failed perfusion imaging. Overall, 42% had mismatch (56% at <6 h; 41% at 12-24 h; 23% at 24-48 h). Agreement for mismatch by visual versus volume assessment was fair using MTT (kappa 0.59, 95% CI 0.34-0.84) but poor using CBF (kappa 0.24, 95% CI 0.01-0.48). Mismatch by either definition was not associated with functional outcome, even when the analysis was restricted to just those with mismatch. Visual estimation is a reasonable proxy for mismatch volume on MTT but not CBF. Perfusion is more difficult for acute stroke patients than diffusion imaging. Mismatch is present in many patients beyond 12 h after stroke. Mismatch alone does not distinguish patients with good and poor prognosis; both can do well or poorly. Other factors, e.g. reperfusion, may influence outcome more strongly, even in patients without mismatch. PMID:19536582

  7. WE-G-18C-09: Separating Perfusion and Diffusion Components From Diffusion Weighted MRI of Rectum Tumors Based On Intravoxel Incoherent Motion (IVIM) Analysis

    SciTech Connect

    Tyagi, N; Wengler, K; Mazaheri, Y; Hunt, M; Deasy, J; Gollub, M

    2014-06-15

    Purpose: Pseudodiffusion arises from the microcirculation of blood in the randomly oriented capillary network and contributes to the signal decay acquired using a multi-b value diffusion weighted (DW)-MRI sequence. This effect is more significant at low b-values and should be properly accounted for in apparent diffusion coefficient (ADC) calculations. The purpose of this study was to separate perfusion and diffusion component based on a biexponential and a segmented monoexponential model using IVIM analysis Methods. The signal attenuation is modeled as S(b) = S0[(1−f)exp(−bD) + fexp(−bD*)]. Fitting the biexponetial decay leads to the quantification of D, the true diffusion coefficient, D*, the pseudodiffusion coefficient, and f, the perfusion fraction. A nonlinear least squares fit and two segmented monoexponential models were used to derive the values for D, D*,‘and f. In the segmented approach b = 200 s/mm{sup 2} was used as the cut-off value for calculation of D. DW-MRI's of a rectum cancer patient were acquired before chemotherapy, before radiation therapy (RT), and 4 weeks into RT and were investigated as an example case. Results: Mean ADC for the tumor drawn on the DWI cases was 0.93, 1.0 and 1.13 10{sup −3}×mm{sup 2}/s before chemotherapy, before RT and 4 weeks into RT. The mean (D.10{sup −3} × mm{sup 2}/s, D* 10{sup −3} × mm{sup 2}/s, and f %) based on biexponential fit was (0.67, 18.6, and 27.2%), (0.72, 17.7, and 28.9%) and (0.83,15.1, and 30.7%) at these time points. The mean (D, D* f) based on segmented fit was (0.72, 10.5, and 12.1%), (0.72, 8.2, and 17.4%) and (.82, 8.1, 16.5%) Conclusion: ADC values are typically higher than true diffusion coefficients. For tumors with significant perfusion effect, ADC should be analyzed at higher b-values or separated from the perfusion component. Biexponential fit overestimates the perfusion fraction because of increased sensitivity to noise at low b-values.

  8. Detecting the subregion proceeding to infarction in hypoperfused cerebral tissue: a study with diffusion and perfusion weighted MRI.

    PubMed

    Liu, Y; Karonen, J O; Vanninen, R L; Nuutinen, J; Perkiö, J; Vainio, P A; Soimakallio, S; Aronen, H J

    2003-06-01

    Diffusion and perfusion weighted MRI have been widely used in ischaemic stroke. We studied 17 patients in whom ischaemic areas showed an ischaemic core, an area of infarct growth and hypoperfused but ultimately surviving tissue. Apparent diffusion coefficients (ADC) were measured on days 1, 2, and 8 in the three subregions and in contralateral control areas. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were measured in these regions on day 1 perfusion maps. On day 1, the ischaemic core had very low ADC and CBF and increased MTT. The ADC in the ischaemic core gradually increased during the week. The area of infarct growth on day 1 had slightly but significantly decreased ADC (96% of control, P=0.028), moderately decreased CBF and increased MTT. On day 1 the hypoperfused but surviving tissue had slightly but significantly increased ADC (103% of control, P=0.001), mildly decreased CBF and increased CBV and MTT. The ADC of the area of infarct growth decreased to the same level as in the ischaemic core on days 2 and 8. That of surviving tissue was still above normal on day 2 (103% of control), but had returned to the normal level by day 8. Measurement of ADC combined with perfusion MRI may help distinguish different subregions in acutely hypoperfused brain. PMID:12750863

  9. Cerebral hemodynamics in human acute ischemic stroke: a study with diffusion- and perfusion-weighted magnetic resonance imaging and SPECT.

    PubMed

    Liu, Y; Karonen, J O; Vanninen, R L; Ostergaard, L; Roivainen, R; Nuutinen, J; Perkiö, J; Könönen, M; Hämäläinen, A; Vanninen, E J; Soimakallio, S; Kuikka, J T; Aronen, H J

    2000-06-01

    Nineteen patients with acute ischemic stroke (<24 hours) underwent diffusion-weighted and perfusion-weighted (PWI) magnetic resonance imaging at the acute stage and 1 week later. Eleven patients also underwent technetium-99m ethyl cysteinate dimer single-photon emission computed tomography (SPECT) at the acute stage. Relative (ischemic vs. contralateral control) cerebral blood flow (relCBF), relative cerebral blood volume, and relative mean transit time were measured in the ischemic core, in the area of infarct growth, and in the eventually viable ischemic tissue on PWI maps. The relCBF was also measured from SPECT. There was a curvilinear relationship between the relCBF measured from PWI and SPECT (r = 0.854; P < 0.001). The tissue proceeding to infarction during the follow-up had significantly lower initial CBF and cerebral blood volume values on PWI maps (P < 0.001) than the eventually viable ischemic tissue had. The best value for discriminating the area of infarct growth from the eventually viable ischemic tissue was 48% for PWI relCBF and 87% for PWI relative cerebral blood volume. Combined diffusion and perfusion-weighted imaging enables one to detect hemodynamically different subregions inside the initial perfusion abnormality. Tissue survival may be different in these subregions and may be predicted. PMID:10894174

  10. [Simultaneous analysis of the distribution of ventilation and diffusive conductance to perfusion in the lungs].

    PubMed

    Yamaguchi, K

    1989-12-01

    Theoretical analysis and experimental observations were performed to establish an essential method allowing demonstration of the characteristics of distribution of ventilation (VA) as well as of diffusive conductance (G) to perfusion (Q) in the lungs. O2, CO2 and CO binding to hemoglobin molecules within erythrocytes, together with six inert gases including SF6, ethane, cyclopropane, halothane, diethyl ether and acetone, possessing various degrees of solubility in blood and different degrees of diffusibility in lung tissue were used as indicator gases. Fifteen patients with interstitial pneumonia of unknown etiology, placed in a supine position, were given a mixture of 21% O2 and 0.1% CO in N2 as the inspired gas and normal saline containing appropriate amounts of the six inert gases via the antecubital vein. After a steady state was established, the expired gas was collected and both arterial and mixed venous blood were simultaneously sampled through the catheter inserted either into the femoral or pulmonary artery. The concentrations of the indicator gases in the samples were measured by gas chromatography, with electrodes or with Scholander gas analyzer. Assuming that the mass transfer efficiency of a given indicator gas at each gas exchange unit would be limited by the ratio of VA to Q (VA/Q) and by that of G/Q, the data obtained from the human subjects were analyzed in terms of a lung model having 20 units along the VA/Q and G/Q axes, respectively. The numerical analysis including the procedure of a simultaneous Bohr integration for O2, CO2 and CO in a pulmonary capillary and the method of weighted least-squares combined with the idea of constrained optimization permitted the data to be transformed into a virtually continuous distribution of Q against VA/Q and G/Q axes. The numerical procedure was strictly tested based on many artificial distributions of VA/Q and G/Q ratios, showing that it could characterize distributions containing up to at least two modes

  11. Myocardial function and perfusion in the CREST syndrome variant of progressive systemic sclerosis. Exercise radionuclide evaluation and comparison with diffuse scleroderma

    SciTech Connect

    Follansbee, W.P.; Curtiss, E.I.; Medsger, T.A. Jr.; Owens, G.R.; Steen, V.D.; Rodnan, G.P.

    1984-09-01

    Myocardial function and perfusion were evaluated in 22 patients with progressive systemic sclerosis with the CREST syndrome using exercise and radionuclide techniques, pulmonary function testing, and chest roentgenography. The results were compared with a similar study of 26 patients with progressive systemic sclerosis with diffuse scleroderma. The prevalence of thallium perfusion abnormalities was similar in the groups with CREST syndrome and diffuse scleroderma, (64 percent versus 77 percent), but the defects were significantly smaller in the CREST syndrome (p less than 0.01). Reperfusion thallium defects in the absence of extramural coronary artery disease were seen in 38 percent of patients with diffuse scleroderma. This finding was not seen in any of the patients with the CREST syndrome. In diffuse scleroderma, abnormalities of both right and left ventricular function were related to larger thallium perfusion defects. In the CREST syndrome, abnormalities of left ventricular function were minor, were seen only during exercise, and were unrelated to thallium perfusion defects. Abnormal resting right ventricular function was seen in 36 percent of the patients with the CREST syndrome and was associated with an isolated decrease in diffusing capacity of carbon monoxide. It is concluded that the cardiac manifestations of the CREST syndrome are distinct from those found in diffuse scleroderma. Unlike diffuse scleroderma, abnormalities of left ventricular function in the CREST syndrome are minor and are unrelated to abnormalities of coronary perfusion. Right ventricular dysfunction in the CREST syndrome appears to be primarily related to pulmonary vascular disease.

  12. Apolipoprotein E polymorphism and acute ischemic stroke: a diffusion- and perfusion-weighted magnetic resonance imaging study.

    PubMed

    Liu, Yawu; Laakso, Mikko P; Karonen, Jari O; Vanninen, Ritva L; Nuutinen, Juho; Soimakallio, Seppo; Aronen, Hannu J

    2002-11-01

    Diffusion- and perfusion-weighted magnetic resonance imaging (MRI) was used to study the putative effects of apolipoprotein E (ApoE) polymorphism in stroke. Thirty-one patients with acute stroke, comparative for age and gender were scanned, nine of whom were ApoE allele epsilon 4 carriers. Initially, less than 24 hours from the onset of stroke, the epsilon 4 carriers had significantly smaller volumes of hypoperfusion on relative cerebral blood volume map (P = 0.001), and smaller infarct volumes (P = 0.008) compared with the noncarriers. By day 8, this difference in the infarct volumes had disappeared, suggesting relatively enhanced infarct growth. On average, the total infarct volume increased 145% of the initial infarct volume in the epsilon 4 carriers, and 84% in the noncarriers. There were strong correlations between the imaging findings and clinical status initially and with the outcome 3 months after the stroke in the epsilon 4 noncarriers, but, with a single exception at acute phase, a lack thereof in the epsilon 4 carriers. These patterns were virtually similar in a subgroup of patients with middle cerebral artery stroke. These data support the hypothesis of increased general vulnerability of the brain in the epsilon 4 carriers. Thus, the effects of ApoE polymorphism should be accounted for when interpreting diffusion- and perfusion-weighted MRI studies, particularly if predicting lesion growth. PMID:12439291

  13. Design and testing of diffuse reflectance sensor for continuous monitoring of cutaneous blood perfusion

    NASA Astrophysics Data System (ADS)

    Zakharov, P.; Talary, M. S.; Caduff, A.

    2009-07-01

    A dual-wavelength reflectance optical sensor for monitoring cutaneous blood perfusion is presented as a part of multisensor glucose monitoring system. A Monte-Carlo simulation of partial differential pathlengths has been used for the optimization of the distance from light source to detector. The simulation indicated that the light pathlength within the upper vascularised skin layers increases before reaching saturation at separation distances larger than 3 mm. Thus the sensor sensitivity does not benefit from larger source-detector distances. At the same time with a higher separation of the detector from the source, the intensity exponentially decreases while undesirable sensitivity to the muscle perfusion increases. The hardware prototype has been developed based on the simulation findings and tested in a laboratory setting and in a home use study by patients with diabetes. For both testing procedures the optical sensor demonstrated high sensitivity to perfusion changes. The effect of initial cutaneous blood increase under the sensor has been observed which can be associated with pressure-induced vasodilation as a response to the sensor application.

  14. Quantitative Perfusion- and Diffusion-Weighted Magnetic Resonance Imaging of Gastrointestinal Cancers Treated With Multikinase Inhibitors: A Pilot Study

    PubMed Central

    Keene, Kimberly S.; Sarver, David B.; Lee, S. Kyle; Beasley, T. Mark; Morgan, Desiree E.; Posey, James A.

    2014-01-01

    ABSTRACT BACKGROUND: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) are often used to detect the early response of solid tumors to an effective therapy. The early changes in intratumoral physiological parameters measured by DCE-MRI/DWI have been evaluated as surrogate biomarkers allowing a tailored treatment for the individual patient. METHODS: Patients with newly diagnosed, biopsy-proven, treatment-naïve gastrointestinal stromal tumor (GIST) or hepatocellular carcinoma (HCC) were enrolled prospectively after institutional review board (IRB)–approved informed consent (5 patients per tumor type). Patients with GIST were treated with sunitinib over 6 weeks. DCE-MRI/DWI was applied before therapy (baseline imaging) and at 2 and 6 weeks after therapy initiation. Patients with HCC were treated with radiation during the first 2 weeks and then with sorafenib for the next 6 weeks. DCE-MRI/DWI was applied in all patients with HCC before and after radiation therapy and at the end of sorafenib therapy. Tumor volume, perfusion parameters (Ktrans, the forward volume-transfer constant, and kep, the reverse reflux-rate constant) and the apparent diffusion coefficient (ADC) were measured. RESULTS: During 2 weeks of sunitinib therapy, GIST volume, Ktrans, and kep decreased 32 ± 13, 45 ± 24, and 42 ± 15%, respectively, whereas ADC increased 76 ± 24%. After 6 weeks of sunitinib therapy, GIST volume, Ktrans, and kep decreased 56 ± 7, 70 ± 7, and 50 ± 12%, respectively, whereas ADC increased 85 ± 33%. After completion of radiation therapy, HCC volume, Ktrans, and kep decreased 34 ± 14, 35 ± 12, and 4 ± 21%, respectively, but ADC increased 21 ± 9%. During the entire 10-week therapeutic period, HCC volume, Ktrans, and kep decreased 65 ± 15, 40 ± 9, and 26 ± 2%, respectively, whereas ADC increased 28 ± 10%. CONCLUSION: DCE-MRI/DWI can measure the perfusion and diffusion changes in GISTs or HCCs treated with

  15. Confusion, Conflict--Cooperation?

    ERIC Educational Resources Information Center

    Lind, Joan Dyste

    1982-01-01

    Ethnocentrism and cultural isolation characterize current curriculum on western civilization. By adopting an interdisciplinary approach, and after overcoming the dual hurdles of confusion and interpersonal conflict in the disciplines, the college curriculum may begin to change this trend. (MSE)

  16. Successful outcome after endovascular thrombolysis for acute ischemic stroke with basis on perfusion-diffusion mismatch after 24 h of symptoms onset

    PubMed Central

    Mattei, Tobias A.; Rehman, Azeem A.; Goulart, Carlos R.; Sória, Marília G.; Rizelio, Vanessa; Meneses, Murilo S.

    2016-01-01

    Background: Although intravenous thrombolysis is the Food and Drug Administration-approved treatment for acute ischemic stroke (AIS) within 3 h, combined intravenous and intra-arterial thrombolysis with endovascular techniques may be able to extend this traditional time window. Case Description: We present the clinical evolution of a 45-year-old male presenting with acute left hemiparesis. Magnetic resonance imaging revealed a small diffusion restriction at the right basal ganglia with perfusion compromise in the entire right middle cerebral artery (MCA) territory. Angiography revealed a complete occlusion of MCA at its M1 segment. The patient underwent endovascular mechanical thrombectomy with additional intra-arterial thrombolysis more than 24 hours after the onset of the initial symptoms and experienced complete vessel recanalization. At 1 year, the patient had global independence with minor residual motor impairment in the left arm. Conclusions: We report the case of a successful thrombolytic therapy following AIS performed more than 24 h after the initial symptoms based on the presence of a perfusion-diffusion mismatch. This report is expected to stimulate the development of future prospective studies with special focus on the role of perfusion-diffusion mismatch in patient selection for treatment of AIS, especially in those presenting outside the traditional time window. PMID:27313971

  17. LISA source confusion

    SciTech Connect

    Crowder, Jeff; Cornish, Neil J.

    2004-10-15

    The Laser Interferometer Space Antenna will detect thousands of gravitational wave sources. Many of these sources will be overlapping in the sense that their signals will have a nonzero cross correlation. Such overlaps lead to source confusion, which adversely affects how well we can extract information about the individual sources. Here we study how source confusion impacts parameter estimation for galactic compact binaries, with emphasis on the effects of the number of overlaping sources, the time of observation, the gravitational wave frequencies of the sources, and the degree of the signal correlations. Our main findings are that the parameter resolution decays exponentially with the number of overlapping sources and superexponentially with the degree of cross correlation. We also find that an extended mission lifetime is key to disentangling the source confusion as the parameter resolution for overlapping sources improves much faster than the usual square root of the observation time.

  18. Is Neurolaw Conceptually Confused?

    PubMed

    Levy, Neil

    2014-06-01

    In Minds, Brains, and Law, Michael Pardo and Dennis Patterson argue that current attempts to use neuroscience to inform the theory and practice of law founder because they are built on confused conceptual foundations. Proponents of neurolaw attribute to the brain or to its parts psychological properties that belong only to people; this mistake vitiates many of the claims they make. Once neurolaw is placed on a sounder conceptual footing, Pardo and Patterson claim, we will see that its more dramatic claims are false or meaningless, though it might be able to provide inductive evidence for particular less dramatic claims (that a defendant may be lying, or lacks control over their behavior, for instance). In response, I argue that the central conceptual confusions identified by Pardo and Patterson are not confusions at all. Though some of the claims made by its proponents are hasty and sometimes they are confused, there are no conceptual barriers to attributing psychological properties to brain states. Neuroscience can play a role in producing evidence that is more reliable than subjective report or behavior; it therefore holds out the possibility of dramatically altering our self-conception as agents and thereby the law. PMID:25009442

  19. Histiocytosis X. Unusual-confusing features of eosinophilic granuloma.

    PubMed

    Pomeranz, S J; Proto, A V

    1986-01-01

    We report our experience with seven cases of eosinophilic granuloma in which unusual and/or confusing features were encountered. These features include: histologic confusion with desquamative interstitial pneumonitis, diffuse histiocytic lymphoma, eosinophilic pneumonia; cysts filled with air and/or fluid; radiographic onset in the eighth decade of life; intratracheal mass; and focal parenchymal consolidation. PMID:3484446

  20. Quantitative MR evaluation of atrophy, as well as perfusion and diffusion alterations within hippocampi in patients with Alzheimer’s disease and mild cognitive impairment

    PubMed Central

    Zimny, Anna; Bladowska, Joanna; Neska, Małgorzata; Petryszyn, Kamila; Guziński, Maciej; Szewczyk, Paweł; Leszek, Jerzy; Sąsiadek, Marek

    2013-01-01

    Background The aim of this study was to evaluate atrophy rates, perfusion, and diffusion disturbances within the hippocampus, which is the site of characteristic changes in Alzheimer’s disease (AD) and mild cognitive impairment (MCI). Material/Methods Thirty patients with AD (mean age 71.2 yrs) – 34 with MCI (mean age 67.7 yrs) and 20 healthy controls (mean age 68.1 yrs) – underwent structural MR examination followed by perfusion and diffusion-weighted imaging on a 1.5 T scanner. Visual rating of hippocampal atrophy, planimetric measurements of hippocampal formation (HF) and perihippocampal fluid spaces (PFSs), and values of relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) were assessed. The results were correlated with the MMSE scores. Results In AD we found decreased size of HF and increased diameters of PFSs and ADC values, compared to MCI and control group. Compared to normal controls, the MCI group showed decreased HF size and increased diameters of only medial PFS. There were no differences in rCBV values among all the subject groups. Planimetric measurements of hippocampal atrophy showed the highest accuracy in diagnosing AD and MCI. In all patients, the increased rates of hippocampal atrophy correlated with the increased ADC values. In MCI, MMSE scores correlated with the HF size and ADC values. Conclusions In AD and MCI, hippocampal atrophy is associated with decreased tissue integrity without coexisting perfusion disturbances. Of all evaluated hippocampal measurements, atrophy rates seem to be the most useful parameters in detecting changes among AD, MCI, and control subjects. PMID:23377218

  1. Multimodal imaging in diagnosis of Alzheimer's disease and amnestic mild cognitive impairment: value of magnetic resonance spectroscopy, perfusion, and diffusion tensor imaging of the posterior cingulate region.

    PubMed

    Zimny, Anna; Szewczyk, Pawel; Trypka, Elzbieta; Wojtynska, Renata; Noga, Leszek; Leszek, Jerzy; Sasiadek, Marek

    2011-01-01

    The purpose of this study was to assess metabolic, perfusion, and microstructural changes within the posterior cingulate area in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) using advanced MR techniques such as: spectroscopy (MRS), perfusion weighted imaging (PWI), and diffusion tensor imaging (DTI). Thirty patients with AD (mean age 71.5 y, MMSE 18), 23 with aMCI (mean age 66 y, MMSE 27.4), and 15 age-matched normal controls (mean age 69 y, MMSE 29.5) underwent conventional MRI followed by MRS, PWI, and DTI on 1.5 Tesla MR unit. Several metabolite ratios (N-acetylaspartate [NAA]/creatine [Cr], choline [Ch]/Cr, myoinositol [mI]/Cr, mI/NAA, mI/Cho) as well as parameters of cerebral blood volume relative to cerebellum and fractional anisotropy were obtained in the posterior cingulate region. The above parameters were correlated with the results of neuropsychological tests. AD patients showed significant abnormalities in all evaluated parameters while subjects with aMCI showed only perfusion and diffusion changes in the posterior cingulate area. Only PWI and DTI measurements revealed significant differences among the three evaluated subject groups. DTI, PWI, and MRS results showed significant correlations with neuropsychological tests. DTI changes correlated with both PWI and MRS abnormalities. Of neuroimaging methods, DTI revealed the highest accuracy in diagnosis of AD and aMCI (0.95, 0.79) followed by PWI (0.87, 0.67) and MRS (0.82, 0.47), respectively. In conclusion, AD is a complex pathology regarding both grey and white matter. DTI seems to be the most useful imaging modality to distinguish between AD, aMCI, and control group, followed by PWI and MRS. PMID:21841260

  2. Intravoxel Incoherent Motion MR Imaging: Comparison of Diffusion and Perfusion Characteristics for Differential Diagnosis of Soft Tissue Tumors

    PubMed Central

    Du, Jun; Li, Kun; Zhang, Weisheng; Wang, Shaowu; Song, Qingwei; Liu, Ailian; Miao, Yanwei; Lang, Zhijin; Zhang, Lina; Zheng, Minting

    2015-01-01

    Abstract We used intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) to explore the possibility of preoperative diagnosis of soft tissue tumors (STTs). This prospective study enrolled 23 patients. Conventional MRI and IVIM examinations were performed on a 3.0T MR imager. Eight (35%) hemangiomas, 11 (47%) benign soft tissue tumors excluding hemangiomas (BSTTEHs) and 4 soft tissue sarcomas (STSs) were assessed. The mean tumor size was about 1652.36 ± 233.66 mm2. Ten b values (0–800 s/mm2) were used to evaluate diffusion and perfusion characteristics of IVIM. IVIM parameters (ADCstandard, ADCslow, ADCfast, and f) of STTs were measured and evaluated for differentiating hemangiomas, BSTTEHs, and STSs. ADCslow and ADCfast value were different for hemangiomas, BSTTEHs, and STSs separately (P < 0.001, P < 0.001, and P = 0.001). ADCslow, cut-off value smaller than 0.93 × 10–3 mm2/s, was the best parameter to differ STSs (0.689 ± 0.173 × 10−3 mm2/s) from hemangiomas (0.933 ± 0.237 × 10−3 mm2/s) and BSTTEHs (1.156 ± 0.120 × 10−3 mm2/s) (P = 0.001). ADCslow (0.93 × 10−3 mm2/s

  3. Current concepts on magnetic resonance imaging (MRI) perfusion-diffusion assessment in acute ischaemic stroke: a review & an update for the clinicians.

    PubMed

    Roldan-Valadez, Ernesto; Lopez-Mejia, Mariana

    2014-12-01

    Recently, several medical societies published joint statements about imaging recommendations for acute stroke and transient ischaemic attack patients. In following with these published guidelines, we considered it appropriate to present a brief, practical and updated review of the most relevant concepts on the MRI assessment of acute stroke. Basic principles of the clinical interpretation of diffusion, perfusion, and MRI angiography (as part of a global MRI protocol) are discussed with accompanying images for each sequence. Brief comments on incidence and differential diagnosis are also included, together with limitations of the techniques and levels of evidence. The purpose of this article is to present knowledge that can be applied in day-to-day clinical practice in specialized stroke units or emergency rooms to attend patients with acute ischaemic stroke or transient ischaemic attack according to international standards. PMID:25758570

  4. WE-G-18C-02: Estimation of Optimal B-Value Set for Obtaining Apparent Diffusion Coefficient Free From Perfusion in Non-Small Cell Lung Cancer

    SciTech Connect

    Karki, K; Hugo, G; Ford, J; Saraiya, S; Weiss, E; Olsen, K; Groves, R

    2014-06-15

    Purpose: Diffusion-weighted MRI (DW-MRI) is increasingly being investigated for radiotherapy planning and response assessment. Selection of a limited number of b-values in DW-MRI is important to keep geometrical variations low and imaging time short. We investigated various b-value sets to determine an optimal set for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in nonsmall cell lung cancer. Methods: Seven patients had 27 DW-MRI scans before and during radiotherapy in a 1.5T scanner. Respiratory triggering was applied to the echo-planar DW-MRI with TR=4500ms approximately, TE=74ms, pixel size=1.98X1.98mm{sub 2}, slice thickness=4–6mm and 7 axial slices. Diffusion gradients were applied to all three axes producing traceweighted images with eight b-values of 0–1000μs/μm{sup 2}. Monoexponential model ADC values using various b-value sets were compared to ADCIVIM using all b-values. To compare the relative noise in ADC maps, intra-scan coefficient of variation (CV) of active tumor volumes was computed. Results: ADCIVIM, perfusion coefficient and perfusion fraction for tumor volumes were in the range of 880-1622 μm{sup 2}/s, 8119-33834 μm{sup 2}/s and 0.104–0.349, respectively. ADC values using sets of 250, 800 and 1000; 250, 650 and 1000; and 250–1000μs/μm{sup 2} only were not significantly different from ADCIVIM(p>0.05, paired t-test). Error in ADC values for 0–1000, 50–1000, 100–1000, 250–1000, 500–1000, and three b-value sets- 250, 500 and 1000; 250, 650 and 1000; and 250, 800 and 1000μs/μm{sup 2} were 15.0, 9.4, 5.6, 1.4, 11.7, 3.7, 2.0 and 0.2% relative to the reference-standard ADCIVIM, respectively. Mean intrascan CV was 20.2, 20.9, 21.9, 24.9, 32.6, 25.8, 25.4 and 24.8%, respectively, whereas that for ADCIVIM was 23.3%. Conclusion: ADC values of two 3 b-value sets

  5. Diffusion, perfusion and the exclusion principles in the structural and functional organization of the living cell: reappraisal of the properties of the 'ground substance'.

    PubMed

    Wheatley, Denys N

    2003-06-01

    The thesis is presented that only within very small microdomains of the cell internum might diffusion operate in the sorting of molecular affinities. Much of cell metabolism is guided and controlled in rate by the speed with which molecules that have to interact encounter one another. What is clear, however, is that the cell does not have a single 'modus operandi' but has the choice of many different strategies, each of which can contribute in different proportion to the rate of ongoing activity. It is probably our own desire to simplify things and use the most (or more) probable strategy that confines our appreciation of the overall robustness of the cell as a 'survival machine'. The main operative process at any given time (perfusion, diffusion or whatever) has always to be considered very carefully in relation to the organisational structure of the cell, which can be transient and fickle but nevertheless has been seen as involving an extensive cytomatrix, a ground substance, within an aqueous environment in which the degree of water structuring is even more fickle. PMID:12756276

  6. Diffusion and Perfusion MRI to Differentiate Treatment-Related Changes Including Pseudoprogression from Recurrent Tumors in High-Grade Gliomas with Histopathologic Evidence

    PubMed Central

    Prager, A.J.; Martinez, N.; Beal, K.; Omuro, A.; Zhang, Z.; Young, R.J.

    2016-01-01

    BACKGROUND AND PURPOSE Treatment-related changes and recurrent tumors often have overlapping features on conventional MR imaging. The purpose of this study was to assess the utility of DWI and DSC perfusion imaging alone and in combination to differentiate treatment-related effects and recurrent high-grade gliomas. MATERIALS AND METHODS We retrospectively identified 68 consecutive patients with high-grade gliomas treated by surgical resection followed by radiation therapy and temozolomide, who then developed increasing enhancing mass lesions indeterminate for treatment-related changes versus recurrent tumor. All lesions were diagnosed by histopathology at repeat surgical resection. ROI analysis was performed of the enhancing lesion on the ADC and DSC maps. Measurements made by a 2D ROI of the enhancing lesion on a single slice were recorded as ADCLesion and rCBVLesion, and measurements made by the most abnormal small fixed diameter ROI as ADCROI and rCBVROI. Statistical analysis was performed with Wilcoxon rank sum tests with P = .05. RESULTS Ten of the 68 patients (14.7%) had treatment-related changes, while 58 patients (85.3%) had recurrent tumor only (n = 19) or recurrent tumor mixed with treatment effect (n = 39). DWI analysis showed higher ADCLesion in treatment-related changes than in recurrent tumor (P = .003). DSC analysis revealed lower relative cerebral blood volume (rCBV)Lesion and rCBVROI in treatment-related changes (P=.003 andP=.011, respectively). Subanalysis of patients with suspected pseudoprogression also revealed higher ADCLesion (P = .001) and lower rCBVLesion (P = .028) and rCBVROI (P = .032) in treatment-related changes. Applying a combined ADCLesion and rCBVLesion model did not outperform either the ADC or rCBV metric alone. CONCLUSIONS Treatment-related changes showed higher diffusion and lower perfusion than recurrent tumor. Similar correlations were found for patients with suspected pseudoprogression. PMID:25593202

  7. The role of diffusion and perfusion weighted imaging in the differential diagnosis of cerebral tumors: a review and future perspectives

    PubMed Central

    2014-01-01

    The role of conventional Magnetic Resonance Imaging (MRI) in the detection of cerebral tumors has been well established. However its excellent soft tissue visualization and variety of imaging sequences are in many cases non-specific for the assessment of brain tumor grading. Hence, advanced MRI techniques, like Diffusion-Weighted Imaging (DWI), Diffusion Tensor Imaging (DTI) and Dynamic-Susceptibility Contrast Imaging (DSCI), which are based on different contrast principles, have been used in the clinical routine to improve diagnostic accuracy. The variety of quantitative information derived from these techniques provides significant structural and functional information in a cellular level, highlighting aspects of the underlying brain pathophysiology. The present work, reviews physical principles and recent results obtained using DWI/DTI and DSCI, in tumor characterization and grading of the most common cerebral neoplasms, and discusses how the available MR quantitative data can be utilized through advanced methods of analysis, in order to optimize clinical decision making. PMID:25609475

  8. Confusion background from compact binaries

    NASA Astrophysics Data System (ADS)

    Regimbau, T.; Hughes, Scott A.

    2010-05-01

    Double neutron stars are one of the most promizing sources for terrestrial gravitational wave interferometers. For actual interferometers and their planned upgrades, the probability of having a signal present in the data is small, but as the sensitivity improves, the detection rate increases and the waveforms may start to overlap, creating a confusion background, ultimately limiting the capabilities of future detectors. The third generation Einstein Telescope, with an horizon of z > 1 and very low frequency "seismic wall" may be affected by such confusion noise. At a minimum, careful data analysis will be require to separate signals which will appear confused. This result should be borne in mind when designing highly advanced future instruments.

  9. In vivo evaluation of brain damage in the course of systemic lupus erythematosus using magnetic resonance spectroscopy, perfusion-weighted and diffusion-tensor imaging.

    PubMed

    Zimny, A; Szmyrka-Kaczmarek, M; Szewczyk, P; Bladowska, J; Pokryszko-Dragan, A; Gruszka, E; Wiland, P; Sasiadek, M

    2014-01-01

    Twenty-two neuropsychiatric (NPSLE) and 13 systemic lupus erythematosus (SLE) patients with a normal appearing brain on plain magnetic resonance (MR) as well as 20 age-matched healthy controls underwent MR spectroscopy (MRS), perfusion-weighted (PWI) and diffusion-tensor imaging (DTI). In MRS NAA/Cr, Cho/Cr and mI/Cr ratios were calculated from the posterior cingulate cortex and left parietal white matter. In PWI, values of cerebral blood volume (CBV) were assessed from 14 regions, including gray and white matter. In DTI fractional anisotropy (FA) values were obtained from 14 white matter tracts including projection, commissural and association fibers. All MR measurements were correlated with clinical data. SLE and NPSLE patients showed significantly (p < 0.05) lower NAA/Cr ratios within both evaluated regions and FA values within the cingulum, as well as a tendency to cortical hypoperfusion. Compared to SLE, NPSLE subjects revealed lower FA values within a wide range of association fibers and corpus callosum. Advanced MR techniques are capable of in vivo detection of complex microstructural brain damage in SLE and NPSLE subjects regarding neuronal loss, mild hypoperfusion and white matter disintegrity. MRS and DTI seem to show the highest usefulness in depicting early changes in normal appearing gray and white matter in SLE patients. PMID:24192079

  10. Confusion

    MedlinePlus

    ... imbalance Illness in an elderly person, such as loss of brain function ( dementia ) Illness in a person with existing neurological disease, such as a stroke Infections Lack of sleep (sleep deprivation) Low blood sugar Low levels of oxygen (for ...

  11. A hybrid microfluidic platform for cell-based assays via diffusive and convective trans-membrane perfusion

    PubMed Central

    Vereshchagina, Elizaveta; Mc Glade, Declan; Glynn, Macdara; Ducrée, Jens

    2013-01-01

    We present a novel 3D hybrid assembly of a polymer microfluidic chip with polycarbonate track-etched membrane (PCTEM) enabling membrane-supported cell culture. Two chip designs have been developed to establish either diffusive or convective reagent delivery using the integrated PCTEM. While it is well suited to a range of cell-based assays, we specifically employ this platform for the screening of a common antitumor chemotoxic agent (mitomycin C – MMC) on the HL60 myeloid leukemia cell line. The toxic activity of MMC is based on the generation of severe DNA damage in the cells. Using either mode of operation, the HL60 cells were cultured on-chip before, during, and after exposure to MMC at concentrations ranging from 0 to 50 μM. Cell viability was analysed off-chip by the trypan blue dye exclusion assay. The results of the on-chip viability assay were found to be consistent with those obtained off-chip and indicated ca. 40% cell survival at MMC concentration of 50 μM. The catalogue of capabilities of the here described cell assay platform comprises of (i) the culturing of cells either under shear-free conditions or under induced through-membrane flows, (ii) the tight time control of the reagent exposure, (iii) the straightforward assembly of devices, (iv) the flexibility on the choice of the membrane, and, prospectively, (v) the amenability for large-scale parallelization. PMID:24404021

  12. Concussion is confusing us all

    PubMed Central

    Sharp, David J

    2015-01-01

    It is time to stop using the term concussion as it has no clear definition and no pathological meaning. This confusion is increasingly problematic as the management of ‘concussed’ individuals is a pressing concern. Historically, it has been used to describe patients briefly disabled following a head injury, with the assumption that this was due to a transient disorder of brain function without long-term sequelae. However, the symptoms of concussion are highly variable in duration, and can persist for many years with no reliable early predictors of outcome. Using vague terminology for post-traumatic problems leads to misconceptions and biases in the diagnostic process, producing uninterpretable science, poor clinical guidelines and confused policy. We propose that the term concussion should be avoided. Instead neurologists and other healthcare professionals should classify the severity of traumatic brain injury and then attempt to precisely diagnose the underlying cause of post-traumatic symptoms. PMID:25977270

  13. Central Nervous System Lymphoma in a 3-Year-Old Male Suffering from a Severe Juvenile Xanthogranuloma – the Usefulness of Perfusion Weighted Imaging and Diffusion Weighted Imaging in the Diagnostics of Pediatric Brain Tumors

    PubMed Central

    Neska-Matuszewska, Małgorzata; Zimny, Anna; Kałwak, Krzysztof; Sąsiadek, Marek J.

    2015-01-01

    Summary Background Primary Central Nervous System Lymphomas (PCNSLs) are rare, malignant brain tumors derived from lymphocytes B. Juvenile xanthogranuloma (JXG) is a non-Langerhans histiocytic cell disorder in children which mostly affects the skin. Rare fatalities have been reported in extracutaneous manifestation. Brain magnetic resonance imaging (MRI) is a method of choice in the diagnostics of all neoplastic CNS lesions. Perfusion weighted imaging (PWI) and diffusion weighted imaging (DWI) allow for more detailed analysis of brain tumors including the rate of neoangiogenesis and cellularity. We presented a pediatric patient suffering from JXG with CNS involvement and the role of brain MRI including DWI and PWI in the evaluation of brain focal lesions. Case Report A 3-year-old male with severe JXG underwent two stem cell transplantations with a development of neurological complications. The patient underwent emergency CT and MRI which revealed a non-specific enhancing focal brain lesion. In DWI it showed restricted diffusion while PWI revealed low values of rCBV and the signal intensity curve returning above the baseline level. Advanced MRI techniques such as DWI and PWI suggested PCNSL. Stereotactic biopsy confirmed PCNSL due to Ebstein-Barr virus reactivation. Conclusions The use of advanced MRI sequences is important to differentiate brain lesions in pediatric patients. The use of PWI and DWI facilitated the diagnosis of PCNSL. It is important to remember that PCNSLs show a very typical pattern of changes visualized with MRI such as: usually strong homogenous enhancement, restricted diffusion and low perfusion. PMID:25624957

  14. Estimation of optimal b-value sets for obtaining apparent diffusion coefficient free from perfusion in non-small cell lung cancer

    NASA Astrophysics Data System (ADS)

    Karki, Kishor; Hugo, Geoffrey D.; Ford, John C.; Olsen, Kathryn M.; Saraiya, Siddharth; Groves, Robert; Weiss, Elisabeth

    2015-10-01

    The purpose of this study was to determine optimal sets of b-values in diffusion-weighted MRI (DW-MRI) for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in non-small cell lung cancer. Ten subjects had 40 DW-MRI scans before and during radiotherapy in a 1.5 T MRI scanner. Respiratory triggering was applied to the echo-planar DW-MRI with \\text{TR}≈ 4500 ms, TE  =  74 ms, eight b-values of 0-1000 μs μm-2, pixel size  =  1.98× 1.98 mm2, slice thickness  =  6 mm, interslice gap  =  1.2 mm, 7 axial slices and total acquisition time ≈6 min. One or more DW-MRI scans together covered the whole tumour volume. Monoexponential model ADC values using various b-value sets were compared to reference-standard ADCIVIM values using all eight b-values. Intra-scan coefficient of variation (CV) of active tumour volumes was computed to compare the relative noise in ADC maps. ADC values for one pre-treatment DW-MRI scan of each of the 10 subjects were computed using b-value pairs from DW-MRI images synthesized for b-values of 0-2000 μs μm-2 from the estimated IVIM parametric maps and corrupted by various Rician noise levels. The square root of mean of squared error percentage (RMSE) of the ADC value relative to the corresponding ADCIVIM for the tumour volume of the scan was computed. Monoexponential ADC values for the b-value sets of 250 and 1000; 250, 500 and 1000; 250, 650 and 1000; 250, 800 and 1000; and 250-1000 μs μm-2 were not significantly different from ADCIVIM values (p>0.05 , paired t-test). Mean error in ADC values for these sets relative to ADCIVIM were within 3.5%. Intra-scan CVs for these sets were comparable to that for ADCIVIM. The monoexponential ADC values for other sets—0-1000 50-1000 100-1000 500-1000 and 250 and 800 μs μm-2 were significantly different from the ADCIVIM values. From Rician noise simulation

  15. Analyzing phonetic confusions using formal concept analysis.

    PubMed

    Peláez-Moreno, C; García-Moral, A I; Valverde-Albacete, F J

    2010-09-01

    Confusion matrices have been used as a tool for the analysis of speech perception or human speech recognition (HSR) for decades. However, they are rarely employed in automatic speech recognition (ASR) mainly due to the lack of a systematic procedure for their exploration. The generalization of formal concept analysis employed in this paper provides a conceptual interpretation of confusion matrices that enables the analysis of the structure of confusions for both human and machine performances. Generalized formal concept analysis transforms confusion matrices into ordered lattices of confusion events, supporting classic results in HSR that identify a hierarchy of virtual articulatory-acoustic channels. Translating this technique into ASR, a detailed map of the relationships among the speech units employed in the system can be traced to make different sources of confusions apparent: the influence of the lexicon, segmentation errors, dialectal variations or limitations of the feature extraction procedures, among others. PMID:20815472

  16. In Acute Stroke, Can CT Perfusion-Derived Cerebral Blood Volume Maps Substitute for Diffusion-Weighted Imaging in Identifying the Ischemic Core?

    PubMed Central

    Copen, William A.; Morais, Livia T.; Wu, Ona; Schwamm, Lee H.; Schaefer, Pamela W.; González, R. Gilberto; Yoo, Albert J.

    2015-01-01

    Background and Purpose In the treatment of patients with suspected acute ischemic stroke, increasing evidence suggests the importance of measuring the volume of the irreversibly injured “ischemic core.” The gold standard method for doing this in the clinical setting is diffusion-weighted magnetic resonance imaging (DWI), but many authors suggest that maps of regional cerebral blood volume (CBV) derived from computed tomography perfusion imaging (CTP) can substitute for DWI. We sought to determine whether DWI and CTP-derived CBV maps are equivalent in measuring core volume. Methods 58 patients with suspected stroke underwent CTP and DWI within 6 hours of symptom onset. We measured low-CBV lesion volumes using three methods: “objective absolute,” i.e. the volume of tissue with CBV below each of six published absolute thresholds (0.9–2.5 mL/100 g), “objective relative,” whose six thresholds (51%-60%) were fractions of mean contralateral CBV, and “subjective,” in which two radiologists (R1, R2) outlined lesions subjectively. We assessed the sensitivity and specificity of each method, threshold, and radiologist in detecting infarction, and the degree to which each over- or underestimated the DWI core volume. Additionally, in the subset of 32 patients for whom follow-up CT or MRI was available, we measured the proportion of CBV- or DWI-defined core lesions that exceeded the follow-up infarct volume, and the maximum amount by which this occurred. Results DWI was positive in 72% (42/58) of patients. CBV maps’ sensitivity/specificity in identifying DWI-positive patients were 100%/0% for both objective methods with all thresholds, 43%/94% for R1, and 83%/44% for R2. Mean core overestimation was 156–699 mL for objective absolute thresholds, and 127–200 mL for objective relative thresholds. For R1 and R2, respectively, mean±SD subjective overestimation were -11±26 mL and -11±23 mL, but subjective volumes differed from DWI volumes by up to 117 and 124

  17. CT and MRI of diffuse lobar involvement pattern in liver pathology.

    PubMed

    Karçaaltincaba, Muşturay; Sirlin, Claude B

    2011-12-01

    Focal, segmental, and diffuse liver pathologies have been described in the literature. This article describes a pattern in which liver pathology is confined to a lobe. This lobar pattern has not been described previously to our knowledge. Herein, we illustrate computed tomography (CT) and magnetic resonance imaging (MRI) findings of diffuse lobar involvement patterns in various liver conditions. Diffuse lobar involvement can be observed in benign (steatosis, hepatic iron overload, cholestasis, perfusion alterations, infarction, alveolar hydatid cysts, trauma, and hemangiomas) and primary malignant (hepatocellular carcinoma) pathologies. Diffuse lobar involvement in metastatic disease appears to be rare. Due in part to their potentially unusual appearances, the diagnosis of lobar pathologies using imaging can be challenging, and entities with lobar patterns can cause diagnostic confusion. Liver MRI can be used as a problem-solving tool for diffuse lobar pathologies detected on ultrasonography and CT. Inand out-of-phase MRI can help in the assessment of lobar fat accumulation. PMID:21053176

  18. Web life: Confused at a Higher Level

    NASA Astrophysics Data System (ADS)

    2010-08-01

    This two-person blog owes its name to Enrico Fermi, who supposedly informed a visiting lecturer that although he used to be confused about the lecture topic, "having listened to your lecture, I am still confused. But on a higher level".

  19. Core Knowledge Confusions among University Students

    ERIC Educational Resources Information Center

    Lindeman, Marjaana; Svedholm, Annika M.; Takada, Mikito; Lonnqvist, Jan-Erik; Verkasalo, Markku

    2011-01-01

    Previous studies have demonstrated that university students hold several paranormal beliefs and that paranormal beliefs can be best explained with core knowledge confusions. The aim of this study was to explore to what extent university students confuse the core ontological attributes of lifeless material objects (e.g. a house, a stone), living…

  20. Consumer Confusion: Reduction Strategies in Higher Education

    ERIC Educational Resources Information Center

    Drummond, Graeme

    2004-01-01

    This paper highlights the increasingly important topic of consumer confusion. Drawing parallels with experiences in the private sector, the concept of consumer confusion is explored within the higher education sector; what causes the phenomenon, how do consumers react to it and how can it be negated/minimised? The expansion and commercialisation…

  1. The Confusion of Molecular Particles with Substances.

    ERIC Educational Resources Information Center

    Selley, N. J.

    1978-01-01

    Objects to the idea of treating molecular particles, such as molecules and atoms, as equal in kind to substances when discussing chemical reactions, thus confusing their different roles in the theory of matter. (GA)

  2. Pulmonary ventilation/perfusion scan

    MedlinePlus

    V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan ... A pulmonary ventilation/perfusion scan is actually two tests. They may be done separately or together. During the perfusion scan, a health ...

  3. Time-resolved multi-channel optical system for assessment of brain oxygenation and perfusion by monitoring of diffuse reflectance and fluorescence

    NASA Astrophysics Data System (ADS)

    Milej, D.; Gerega, A.; Kacprzak, M.; Sawosz, P.; Weigl, W.; Maniewski, R.; Liebert, A.

    2014-03-01

    Time-resolved near-infrared spectroscopy is an optical technique which can be applied in tissue oxygenation assessment. In the last decade this method is extensively tested as a potential clinical tool for noninvasive human brain function monitoring and imaging. In the present paper we show construction of an instrument which allows for: (i) estimation of changes in brain tissue oxygenation using two-wavelength spectroscopy approach and (ii) brain perfusion assessment with the use of single-wavelength reflectometry or fluorescence measurements combined with ICG-bolus tracking. A signal processing algorithm based on statistical moments of measured distributions of times of flight of photons is implemented. This data analysis method allows for separation of signals originating from extra- and intracerebral tissue compartments. In this paper we present compact and easily reconfigurable system which can be applied in different types of time-resolved experiments: two-wavelength measurements at 687 and 832 nm, single wavelength reflectance measurements at 760 nm (which is at maximum of ICG absorption spectrum) or fluorescence measurements with excitation at 760 nm. Details of the instrument construction and results of its technical tests are shown. Furthermore, results of in-vivo measurements obtained for various modes of operation of the system are presented.

  4. Dichotic Listening and Left-Right Confusion

    ERIC Educational Resources Information Center

    Hirnstein, Marco

    2011-01-01

    The present study examined the relationship between individual differences in dichotic listening (DL) and the susceptibility to left-right confusion (LRC). Thirty-six men and 59 women completed a consonant-vowel DL test, a behavioral LRC task, and an LRC self-rating questionnaire. Significant negative correlations between overall DL accuracy and…

  5. Avogadro Number and Mole: A Royal Confusion.

    ERIC Educational Resources Information Center

    Emiliani, Cesare

    1991-01-01

    There is a great deal of confusion in physics and chemistry textbooks, dictionaries, manuals, and handbooks about the definition of Avogadro's number and the term "mole." Avogadro's number is defined simply as the number of atomic mass units in one gram. Mole is defined as the mass of one Avogadro number of identical items. (Author/PR)

  6. Confusion between Odds and Probability, a Pandemic?

    ERIC Educational Resources Information Center

    Fulton, Lawrence V.; Mendez, Francis A.; Bastian, Nathaniel D.; Musal, R. Muzaffer

    2012-01-01

    This manuscript discusses the common confusion between the terms probability and odds. To emphasize the importance and responsibility of being meticulous in the dissemination of information and knowledge, this manuscript reveals five cases of sources of inaccurate statistical language imbedded in the dissemination of information to the general…

  7. When is stacking confusing? The impact of confusion on stacking in deep H I galaxy surveys

    NASA Astrophysics Data System (ADS)

    Jones, Michael G.; Haynes, Martha P.; Giovanelli, Riccardo; Papastergis, Emmanouil

    2016-01-01

    We present an analytic model to predict the H I mass contributed by confused sources to a stacked spectrum in a generic H I survey. Based on the ALFALFA (Arecibo Legacy Fast ALFA) correlation function, this model is in agreement with the estimates of confusion present in stacked Parkes telescope data, and was used to predict how confusion will limit stacking in the deepest Square Kilometre Array precursor H I surveys. Stacking with LADUMA (Looking At the Distant Universe with MeerKAT) and DINGO UDEEP (Deep Investigation of Neutral Gas Origins - Ultra Deep) data will only be mildly impacted by confusion if their target synthesized beam size of 10 arcsec can be achieved. Any beam size significantly above this will result in stacks that contain a mass in confused sources that is comparable to (or greater than) that which is detectable via stacking, at all redshifts. CHILES (COSMOS H I Large Extragalactic Survey) 5 arcsec resolution is more than adequate to prevent confusion influencing stacking of its data, throughout its bandpass range. FAST (Five hundred metre Aperture Spherical Telescope) will be the most impeded by confusion, with H I surveys likely becoming heavily confused much beyond z = 0.1. The largest uncertainties in our model are the redshift evolution of the H I density of the Universe and the H I correlation function. However, we argue that the two idealized cases we adopt should bracket the true evolution, and the qualitative conclusions are unchanged regardless of the model choice. The profile shape of the signal due to confusion (in the absence of any detection) was also modelled, revealing that it can take the form of a double Gaussian with a narrow and wide component.

  8. Perfusion visualization and analysis for pulmonary embolism

    NASA Astrophysics Data System (ADS)

    Vaz, Michael S.; Kiraly, Atilla P.; Naidich, David P.; Novak, Carol L.

    2005-04-01

    Given the nature of pulmonary embolism (PE), timely and accurate diagnosis is critical. Contrast enhanced high-resolution CT images allow physicians to accurately identify segmental and sub-segmental emboli. However, it is also important to assess the effect of such emboli on the blood flow in the lungs. Expanding upon previous research, we propose a method for 3D visualization of lung perfusion. The proposed method allows users to examine perfusion throughout the entire lung volume at a single glance, with areas of diminished perfusion highlighted so that they are visible independent of the viewing location. This may be particularly valuable for better accuracy in assessing the extent of hemodynamic alterations resulting from pulmonary emboli. The method also facilitates user interaction and may help identify small peripheral sub-segmental emboli otherwise overlooked. 19 patients referred for possible PE were evaluated by CT following the administration of IV contrast media. An experienced thoracic radiologist assessed the 19 datasets with 17 diagnosed as being positive for PE with multiple emboli. Since anomalies in lung perfusion due to PE can alter the distribution of parenchymal densities, we analyzed features collected from histograms of the computed perfusion maps and demonstrate their potential usefulness as a preliminary test to suggest the presence of PE. These histogram features also offer the possibility of distinguishing distinct patterns associated with chronic PE and may even be useful for further characterization of changes in perfusion or overall density resulting from associated conditions such as pneumonia or diffuse lung disease.

  9. Applying the concept of consumer confusion to healthcare: development and validation of a patient confusion model.

    PubMed

    Gebele, Christoph; Tscheulin, Dieter K; Lindenmeier, Jörg; Drevs, Florian; Seemann, Ann-Kathrin

    2014-01-01

    As patient autonomy and consumer sovereignty increase, information provision is considered essential to decrease information asymmetries between healthcare service providers and patients. However, greater availability of third party information sources can have negative side effects. Patients can be confused by the nature, as well as the amount, of quality information when making choices among competing health care providers. Therefore, the present study explores how information may cause patient confusion and affect the behavioral intention to choose a health care provider. Based on a quota sample of German citizens (n = 198), the present study validates a model of patient confusion in the context of hospital choice. The study results reveal that perceived information overload, perceived similarity, and perceived ambiguity of health information impact the affective and cognitive components of patient confusion. Confused patients have a stronger inclination to hastily narrow down their set of possible decision alternatives. Finally, an empirical analysis reveals that the affective and cognitive components of patient confusion mediate perceived information overload, perceived similarity, and perceived ambiguity of information. PMID:25595013

  10. Confusion and hypnotics in demented patients

    PubMed Central

    Mead, M. G.; Castleden, C. M.

    1982-01-01

    Eleven elderly confused patients were given a single dose of chlormethiazole, temazepam and placebo on separate nights with-in a 10-day period. There was no statistically significant difference between the three treatments the next morning in any of the tests, which included subjective and objective measures of mental ability, orientation and hangover effect. These results mirror those previously found in normal, healthy, elderly patients, and do not therefore support the contention that hypnotics increase confusion in demented patients, or that such patients are more sensitive to their actions. Indeed, plasma drug concentrations were on average twice as high in demented as in normal elderly subjects, thus raising the possibility of decreased sensitivity in the demented group. There was little correlation between plasma concentration and pharmacological effect. PMID:6130151

  11. An analysis of auditory alphabet confusions.

    PubMed

    Walker, M E

    1989-04-01

    The present study, using the nonhierarchical overlapping clustering algorithm MAPCLUS to fit the Shepard-Arabie (1979) ADCLUS model, attempted to derive a set of features that would accurately describe the auditory alphabet confusions present in the data matrices of Conrad (1964) and Hull (1973). Separate nine-cluster solutions accounted for 80% and 89% of the variance in the matrices, respectively. The clusters revealed that the most frequently confused letter names contained common vowels and phonetically similar consonants. Further analyses using INDCLUS, an individual differences extension of the MAPCLUS algorithm and ADCLUS model, indicated that while the patterns of errors in the two matrices were remarkably similar, some differences were also apparent. These differences reflected the differing amounts of background noise present in the two studies. PMID:2710632

  12. Analyzing Mode Confusion via Model Checking

    NASA Technical Reports Server (NTRS)

    Luettgen, Gerald; Carreno, Victor

    1999-01-01

    Mode confusion is one of the most serious problems in aviation safety. Today's complex digital flight decks make it difficult for pilots to maintain awareness of the actual states, or modes, of the flight deck automation. NASA Langley leads an initiative to explore how formal techniques can be used to discover possible sources of mode confusion. As part of this initiative, a flight guidance system was previously specified as a finite Mealy automaton, and the theorem prover PVS was used to reason about it. The objective of the present paper is to investigate whether state-exploration techniques, especially model checking, are better able to achieve this task than theorem proving and also to compare several verification tools for the specific application. The flight guidance system is modeled and analyzed in Murphi, SMV, and Spin. The tools are compared regarding their system description language, their practicality for analyzing mode confusion, and their capabilities for error tracing and for animating diagnostic information. It turns out that their strengths are complementary.

  13. Medial perirhinal cortex disambiguates confusable objects

    PubMed Central

    Tyler, Lorraine K.; Monsch, Andreas U.; Taylor, Kirsten I.

    2012-01-01

    Our brain disambiguates the objects in our cluttered visual world seemingly effortlessly, enabling us to understand their significance and to act appropriately. The role of anteromedial temporal structures in this process, particularly the perirhinal cortex, is highly controversial. In some accounts, the perirhinal cortex is necessary for differentiating between perceptually and semantically confusable objects. Other models claim that the perirhinal cortex neither disambiguates perceptually confusable objects nor plays a unique role in semantic processing. One major hurdle to resolving this central debate is the fact that brain damage in human patients typically encompasses large portions of the anteromedial temporal lobe, such that the identification of individual substructures and precise neuroanatomical locus of the functional impairments has been difficult. We tested these competing accounts in patients with Alzheimer’s disease with varying degrees of atrophy in anteromedial structures, including the perirhinal cortex. To assess the functional contribution of each anteromedial temporal region separately, we used a detailed region of interest approach. From each participant, we obtained magnetic resonance imaging scans and behavioural data from a picture naming task that contrasted naming performance with living and non-living things as a way of manipulating perceptual and semantic confusability; living things are more similar to one another than non-living things, which have more distinctive features. We manually traced neuroanatomical regions of interest on native-space cortical surface reconstructions to obtain mean thickness estimates for the lateral and medial perirhinal cortex and entorhinal cortex. Mean cortical thickness in each region of interest, and hippocampal volume, were submitted to regression analyses predicting naming performance. Importantly, atrophy of the medial perirhinal cortex, but not lateral perirhinal cortex, entorhinal cortex or

  14. Keats'"Negative Capability" and "Disinterestedness": A Confusion of Ideals

    ERIC Educational Resources Information Center

    Guilhamet, Leon M.

    1970-01-01

    Though the moral and poetic realms need not be kept separate, keats saw the relationship between them in a confused way....(This article is) an attempt to specify the sources of the confusion in Keats's mind." (Author)

  15. Confusion and Complex Learning during Interactions with Computer Learning Environments

    ERIC Educational Resources Information Center

    Lehman, Blair; D'Mello, Sidney; Graesser, Art

    2012-01-01

    Folk wisdom holds that being confused is detrimental to learning. However, research on emotions and learning suggest a somewhat more complex relationship between confusion and learning outcomes. In fact, it has been proposed that impasses that trigger states of cognitive disequilibrium and confusion can create opportunities for deep learning of…

  16. Making Sense of Confusion: Relating Performance, Confidence, and Self-Efficacy to Expressions of Confusion in an Introductory Physics Class

    ERIC Educational Resources Information Center

    Dowd, Jason E.; Araujo, Ives; Mazur, Eric

    2015-01-01

    Although confusion is generally perceived to be negative, educators dating as far back as Socrates, who asked students to question assumptions and wrestle with ideas, have challenged this notion. Can confusion be productive? How should instructors interpret student expressions of confusion? During two semesters of introductory physics that…

  17. Confusion and its dynamics during device comprehension with breakdown scenarios.

    PubMed

    D'Mello, Sidney; Graesser, Art

    2014-09-01

    The incidence and dynamics of confusion during complex learning and problem solving were investigated in an experiment where participants first read illustrated texts on everyday devices (e.g., an electric bell) followed by breakdown scenarios reflecting device malfunctions (e.g., "When a person rang the bell there was a short ding and then no sound was heard"). The breakdown scenarios were expected to trigger impasses and put participants in a state of cognitive disequilibrium where they would experience confusion and engage in effortful confusion resolution activities in order to restore equilibrium. The results confirmed that participants reported more confusion when presented with the breakdown scenarios compared to control scenarios that involved focusing on important device components in the absence of malfunctions. A second-by-second analysis of the dynamics of confusion yielded two characteristic trajectories that distinguished participants who partially resolved their confusion from those who remained confused. Participants who were successful in partial confusion resolution while processing the breakdowns outperformed their counterparts on knowledge assessments after controlling for scholastic aptitude, engagement, and frustration. This effect was amplified for those who were highly confused by the breakdowns. There was no direct breakdown vs. control effect on learning, but being actively engaged and partially resolving confusion during breakdown processing were positive predictors of increased learning with the breakdown compared to control scenarios. Implications of our findings for theories that highlight the role of impasses, cognitive disequilibrium, and confusion to learning are discussed. PMID:24973629

  18. EBM, HTA, and CER: Clearing the Confusion

    PubMed Central

    Luce, Bryan R; Drummond, Michael; Jönsson, Bengt; Neumann, Peter J; Schwartz, J Sanford; Siebert, Uwe; Sullivan, Sean D

    2010-01-01

    Context: The terms evidence-based medicine (EBM), health technology assessment (HTA), comparative effectiveness research (CER), and other related terms lack clarity and so could lead to miscommunication, confusion, and poor decision making. The objective of this article is to clarify their definitions and the relationships among key terms and concepts. Methods: This article used the relevant methods and policy literature as well as the websites of organizations engaged in evidence-based activities to develop a framework to explain the relationships among the terms EBM, HTA, and CER. Findings: This article proposes an organizing framework and presents a graphic demonstrating the differences and relationships among these terms and concepts. Conclusions: More specific terminology and concepts are necessary for an informed and clear public policy debate. They are even more important to inform decision making at all levels and to engender more accountability by the organizations and individuals responsible for these decisions. PMID:20579285

  19. Why the confusion in Hashimoto's encephalopathy?

    PubMed

    Jayasekera, Bodiabaduge A P; McShane, Michael Anthony; Roy, Prem; Anand, Geetha

    2011-01-01

    A 13-year-old girl presented with an afebrile seizure followed by prolonged confusion and visual hallucinations. Initial investigations in the form of blood tests, cerebrospinal fluid analysis and head imaging by CT, were normal. She represented with two further episodes within a period of 3 weeks. Further investigations considering infective, metabolic and some autoimmune causes of encephalopathy were negative. An MRI head scan was normal. Thyroid function testing disclosed primary hypothyroidism and elevated antithyroid antibodies. She responded well to glucocorticoid therapy for presumed Hashimoto's encephalopathy (HE). HE describes patients with various neurological manifestations with elevated titres of antithyroid antibodies. There are no clear criteria for diagnosis, with many cases labelled as HE. Responses to corticosteroid therapy are favourable. In patients with unexplained encephalopathy, HE should be considered given the favourable response to glucocorticoid therapy. PMID:22691944

  20. Econometric models for predicting confusion crop ratios

    NASA Technical Reports Server (NTRS)

    Umberger, D. E.; Proctor, M. H.; Clark, J. E.; Eisgruber, L. M.; Braschler, C. B. (Principal Investigator)

    1979-01-01

    Results for both the United States and Canada show that econometric models can provide estimates of confusion crop ratios that are more accurate than historical ratios. Whether these models can support the LACIE 90/90 accuracy criterion is uncertain. In the United States, experimenting with additional model formulations could provide improved methods models in some CRD's, particularly in winter wheat. Improved models may also be possible for the Canadian CD's. The more aggressive province/state models outperformed individual CD/CRD models. This result was expected partly because acreage statistics are based on sampling procedures, and the sampling precision declines from the province/state to the CD/CRD level. Declining sampling precision and the need to substitute province/state data for the CD/CRD data introduced measurement error into the CD/CRD models.

  1. Myocardial infarction--fusion or confusion?

    PubMed

    Ardhanari, Sivakumar; Shah, Ashok J; Thakur, Ranjan K

    2009-09-01

    A patient with a dualchamber pacemaker with dynamic atrioventricular delay (AVD) experienced acute substernal chest pain. The rhythm strip in the ambulance showed intermittent ST elevation in the inferior leads. An emergent cardiac catheterization revealed nonobstructive coronary artery disease. Rate-responsive dual-chamber pacing with dynamic AVD was responsible for varying devvgrees of ventricular fusion due to competition with the patient's normal conduction. Intermittent ST elevation, evident only during ventricular fusion should have suggested secondary ventricular repolarization and not myocardial injury, but concomitant chest pain and inconspicuous bipolar pacing artifacts added to the confusion. Ventricular pacing may not only mask acute ST-T changes due to myocardial injury, but can also mimic acute myocardial infarction. PMID:19726827

  2. Experimental glomerulonephritis in the isolated perfused rat kidney.

    PubMed Central

    Couser, W G; Steinmuller, D R; Stilmant, M M; Salant, D J; Lowenstein, L M

    1978-01-01

    The development of immune deposits on the subepithelial surface of the glomerular capillary wall was studied in isolated rat kidneys perfused at controlled perfusion pressure, pH, temperature, and flow rates with recirculating oxygenated perfusate containing bovine serum albumin (BSA) in buffer and sheep antibody to rat proximal tubular epithelial cell brush border antigen (Fx1A). Control kidney were perfused with equal concentrations of non-antibody immunoglobulin (Ig)G. Renal function was monitored by measuring inulin clearance, sodium reabsorption, and urine flow as well as BSA excretion and fractional clearance. Perfused kidneys were studied by light, immunofluorescence, and electron microscopy. All kidneys perfused with anti-Fx1A developed diffuse, finely granular deposits of IgG along the glomerular capillary wall by immunofluorescence. Electron microscopy revealed these deposits to be localized exclusively in the subepithelial space and slit pores. Similar deposits were produced in a nonrecirculating perfusion system, thereby excluding the formation of immune complexes in the perfusate caused by renal release of tubular antigen. Control kidneys perfused with nonantibody IgG did not develop glomerular immune deposits. Renal function and BSA excretion were the same in experimental and control kidneys. Glomerular deposits in antibody perfused kidneys were indistinguishable from deposits in rats injected with anti-Fx1A or immunized with Fx1A to produce autologous immune complex nephropathy. These studies demonstrate that subepithelial immune deposits can be produced in the isolated rat kidney by perfusion with specific antibody to Fx1A in the absence of circulating immune complexes. In this model deposits result from in situ complex formation rather than circulating immune complex deposition. Images PMID:372233

  3. Star Confusion Effect on SIM PlanetQuest Astrometric Performance

    NASA Technical Reports Server (NTRS)

    Zhai, C.; Yu, M.; Milman, M.; Fathpour, N.; Morales, M.; Nemati, B.; Regehr, M.; Heflin, M.; Sievers, L.

    2007-01-01

    SIM PlanetQuest will measure star positions to an accuracy of a few microarcseconds using precise white light fringe measurements. One challenge for SIM observation scenario is "star confusion," where multiple stars are present in the instrument field of view. This is especially relevant for observing dim science targets because the density of number of stars increases rapidly with star magnitude. We study the effect of star confusion on the SIM astrometric performance due to systematic fringe errors caused by the extra photons from the confusion star(s}. Since star confusion from multiple stars may be analyzed as a linear superposition of the effect from single star confusion, we quantify the astrometric errors due to single star confusion surveying over many spectral types, including AOV, FOV, K5III, and MOV, and for various visual magnitude differences. To the leading order, the star confusion effect is characterized by the magnitude difference, spectral difference, and the angular separation between the target and confusion stars.Strategies for dealing with star confusion are presented. For example, since the presence of additional sources in the field of view leads to inconsistent delay estimates from different channels, with sufficient signal to noise ratio, the star confusion can be detected using chi-square statistics of fringe measurements from multiple spectral channels. An interesting result is that the star confusion can be detected even though the interferometer cannot resolve the separation between the target and confusion stars when their spectra are sufficiently different. Other strategies for mitigating the star confusion effect are also discussed.

  4. Making sense of confusion: Relating performance, confidence, and self-efficacy to expressions of confusion in an introductory physics class

    NASA Astrophysics Data System (ADS)

    Dowd, Jason E.; Araujo, Ives; Mazur, Eric

    2015-06-01

    Although confusion is generally perceived to be negative, educators dating as far back as Socrates, who asked students to question assumptions and wrestle with ideas, have challenged this notion. Can confusion be productive? How should instructors interpret student expressions of confusion? During two semesters of introductory physics that involved Just-in-Time Teaching (JiTT) and research-based reading materials, we evaluated performance on reading assignments while simultaneously measuring students' self-assessment of their confusion over the preclass reading material (N =137 ; Nfall=106 , Nspring=88 ). We examined the relationship between confusion and correctness, confidence in reasoning, and (in the spring) precourse self-efficacy. We find that student expressions of confusion before coming to class are negatively related to correctness on preclass content-related questions, confidence in reasoning on those questions, and self-efficacy, but weakly positively related to final grade when controlling for these factors (β =0.23 , p =0.03 ).

  5. Intraosseous haemangioma: semantic and medical confusion.

    PubMed

    Kadlub, N; Dainese, L; Coulomb-L'Hermine, A; Galmiche, L; Soupre, V; Lepointe, H Ducou; Vazquez, M-P; Picard, A

    2015-06-01

    The literature is rich in case reports of intraosseous haemangioma, although most of these are actually cases of venous or capillary malformations. To illustrate this confusion in terminology, we present three cases of slow-flow vascular malformations misnamed as intraosseous haemangioma. A retrospective study of children diagnosed with intraosseous haemangioma was conducted. Clinical and radiological data were evaluated. Histopathological examinations and immunohistochemical studies were redone by three independent pathologists to classify the lesions according to the International Society for the Study of Vascular Anomalies (ISSVA) and World Health Organization (WHO) classifications. Three children who had presented with jaw haemangiomas were identified. Computed tomography scan patterns were not specific. All tumours were GLUT-1-negative and D2-40-negative. The lesions were classified as central haemangiomas according to the WHO, and as slow-flow malformations according to the ISSVA. The classification of vascular anomalies is based on clinical, radiological, and histological differences between vascular tumours and malformations. Based on this classification, the evolution of the lesion can be predicted and adequate treatment applied. The binary ISSVA classification is widely accepted and should be applied for all vascular lesions. PMID:25703595

  6. Ex vivo lung perfusion.

    PubMed

    Reeb, Jeremie; Cypel, Marcelo

    2016-03-01

    Lung transplantation is an established life-saving therapy for patients with end-stage lung disease. Unfortunately, greater success in lung transplantation is hindered by a shortage of lung donors and the relatively poor early-, mid-, and long-term outcomes associated with severe primary graft dysfunction. Ex vivo lung perfusion has emerged as a modern preservation technique that allows for a more accurate lung assessment and improvement in lung quality. This review outlines the: (i) rationale behind the method; (ii) techniques and protocols; (iii) Toronto ex vivo lung perfusion method; (iv) devices available; and (v) clinical experience worldwide. We also highlight the potential of ex vivo lung perfusion in leading a new era of lung preservation. PMID:26700566

  7. "Apparent Weight": A Concept that Is Confusing and Unnecessary

    ERIC Educational Resources Information Center

    Bartlett, Albert A.

    2010-01-01

    Two recent articles make prominent use of the concept of "apparent weight." The concept of "apparent weight" leads to two confusing inconsistencies. We need to know that with very little change in our representations, we can give our students an improved understanding of "weight" without ever having to invent the appealing but confusing concept of…

  8. Clustering, Seriation, and Subset Extraction of Confusion Data

    ERIC Educational Resources Information Center

    Brusco, Michael J.; Steinley, Douglas

    2006-01-01

    The study of confusion data is a well established practice in psychology. Although many types of analytical approaches for confusion data are available, among the most common methods are the extraction of 1 or more subsets of stimuli, the partitioning of the complete stimulus set into distinct groups, and the ordering of the stimulus set. Although…

  9. Dyscalculia, Dysgraphia, and Left-Right Confusion from a Left Posterior Peri-Insular Infarct

    PubMed Central

    Bhattacharyya, S.; Cai, X.; Klein, J. P.

    2014-01-01

    The Gerstmann syndrome of dyscalculia, dysgraphia, left-right confusion, and finger agnosia is generally attributed to lesions near the angular gyrus of the dominant hemisphere. A 68-year-old right-handed woman presented with sudden difficulty completing a Sudoku grid and was found to have dyscalculia, dysgraphia, and left-right confusion. Magnetic resonance imaging (MRI) showed a focus of abnormal reduced diffusivity in the left posterior insula and temporoparietal operculum consistent with acute infarct. Gerstmann syndrome from an insular or peri-insular lesion has not been described in the literature previously. Pathological and functional imaging studies show connections between left posterior insular region and inferior parietal lobe. We postulate that the insula and operculum lesion disrupted key functional networks resulting in a pseudoparietal presentation. PMID:24817791

  10. Dyscalculia, dysgraphia, and left-right confusion from a left posterior peri-insular infarct.

    PubMed

    Bhattacharyya, S; Cai, X; Klein, J P

    2014-01-01

    The Gerstmann syndrome of dyscalculia, dysgraphia, left-right confusion, and finger agnosia is generally attributed to lesions near the angular gyrus of the dominant hemisphere. A 68-year-old right-handed woman presented with sudden difficulty completing a Sudoku grid and was found to have dyscalculia, dysgraphia, and left-right confusion. Magnetic resonance imaging (MRI) showed a focus of abnormal reduced diffusivity in the left posterior insula and temporoparietal operculum consistent with acute infarct. Gerstmann syndrome from an insular or peri-insular lesion has not been described in the literature previously. Pathological and functional imaging studies show connections between left posterior insular region and inferior parietal lobe. We postulate that the insula and operculum lesion disrupted key functional networks resulting in a pseudoparietal presentation. PMID:24817791

  11. Importance of capillary perfusion.

    PubMed

    Hardaway, R M

    1979-11-01

    Perfusion is more critical than oxygen in the maintenance of cell viability. A high hematocrit or high fibrinogen level increases blood viscosity and predisposes to disseminated intravascular coagulation. It is recommended that a hematocrit of about 30 be maintained in periods of circulatory stress such as shock or extracorporeal circulation. PMID:495856

  12. Distribution of perfusion.

    PubMed

    Glenny, Robb; Robertson, H Thomas

    2011-01-01

    Local driving pressures and resistances within the pulmonary vascular tree determine the distribution of perfusion in the lung. Unlike other organs, these local determinants are significantly influenced by regional hydrostatic and alveolar pressures. Those effects on blood flow distribution are further magnified by the large vertical height of the human lung and the relatively low intravascular pressures in the pulmonary circulation. While the distribution of perfusion is largely due to passive determinants such as vascular geometry and hydrostatic pressures, active mechanisms such as vasoconstriction induced by local hypoxia can also redistribute blood flow. This chapter reviews the determinants of regional lung perfusion with a focus on vascular tree geometry, vertical gradients induced by gravity, the interactions between vascular and surrounding alveolar pressures, and hypoxic pulmonary vasoconstriction. While each of these determinants of perfusion distribution can be examined in isolation, the distribution of blood flow is dynamically determined and each component interacts with the others so that a change in one region of the lung influences the distribution of blood flow in other lung regions. PMID:23737171

  13. Regional Myocardial Perfusion Rates in Patients with Coronary Artery Disease

    PubMed Central

    Cannon, Paul J.; Dell, Ralph B.; Dwyer, Edward M.

    1972-01-01

    Regional myocardial perfusion rates were estimated from the myocardial washout of 133Xenon in 24 patients with heart disease whose coronary arteriograms were abnormal and 17 similar subjects whose coronary arteriograms were judged to be normal. Disappearance rates of 133Xe from multiple areas of the heart were monitored externally with a multiple-crystal scintillation camera after the isotope had been injected into a coronary artery and local myocardial perfusion rates were calculated by the Kety formula. The mean myocardial perfusion rates in the left ventricle exceeded those in the right ventricle or atrial regions in subjects without demonstrable coronary artery disease. In this group there was a significant lack of homogeneity of local perfusion rates in left ventricular myocardium; the mean coefficient of variation of left ventricular local perfusion rates was 15.8%. In the patients with radiographically demonstrable coronary artery disease, a variety of myocardial perfusion patterns were observed. Local capillary blood flow rates were depressed throughout the myocardium of patients with diffuse coronary disease but were subnormal only in discrete myocardial regions of others with localized occlusive disease. Local myocardial perfusion rates were similar to those found in the group with normal coronary arteriograms in patients with slight degrees of coronary disease and in those areas of myocardium distal to marked coronary constrictions or occlusions which were well supplied by collateral vessels. In subjects with right coronary disease, the mean right ventricular perfusion rates were significantly subnormal; in seven subjects of this group perfusion of the inferior left ventricle by a dominant right coronary artery was absent or depressed. The average mean left ventricular perfusion rate of 12 subjects with significant disease of two or more branches of the left coronary artery was significantly lower than that of the group with normal left coronary

  14. Incidence and Prevalence: Confusion in Need of Clarification.

    ERIC Educational Resources Information Center

    Marozas, Donald S.; And Others

    1980-01-01

    Confusing definitions presented in textbooks are reviewed. Many texts used the terms incidence and prevalence interchangeably, some did not define the terms at all, and others presented completely contradictory definitions. A definition is recommended for use and clarification. (Author)

  15. PREVENTING SURGICAL CONFUSIONS IN OPHTHALMOLOGY (AN AMERICAN OPHTHALMOLGICAL SOCIETY THESIS)

    PubMed Central

    Simon, John W.

    2007-01-01

    Purpose Surgical confusions have been rarely studied, especially in ophthalmology. The author hypothesized that such confusions occur rarely but are unacceptable in the public, legal, and regulatory arenas; often occur in circumstances presenting predictable risk; more often involve wrong lens implant than wrong eye, procedure, or patient; and can be prevented by following the Universal Protocol. Methods A retrospective series of 106 cases occurring between 1982 and 2005 included 42 closed files from the Ophthalmic Mutual Insurance Company and 64 cases reported to the New York State Health Department. Records were grouped by procedure planned and analyzed to answer these questions: How did the error occur? By whom and when was the error recognized? Who was responsible? Was the patient informed? What was done to the patient? What was the outcome? What liability payments were made? What policy changes or sanctions resulted? Was the error preventable by following the Universal Protocol? Results The most common confusion was wrong lens implant, accounting for 67 (63%) of the 106 cases. Wrong eye surgery occurred in 15 cases, wrong eye blocks in 14, wrong patient/procedure in 8, and wrong corneal transplant in 2. In 16 cases, the Universal Protocol would have been unlikely to prevent the confusion. Conclusions Surgical confusions occur infrequently and usually cause little or no permanent injury, but they may be devastating to the patient, the physician, and the profession. Measures to prevent such confusions, including the Universal Protocol and related checklists, deserve the acceptance, support, and active participation of ophthalmologists. PMID:18427628

  16. A disposable flexible skin patch for clinical optical perfusion monitoring at multiple depths

    NASA Astrophysics Data System (ADS)

    Farkas, Dana L.; Kolodziejski, Noah J.; Stapels, Christopher J.; McAdams, Daniel R.; Fernandez, Daniel E.; Podolsky, Matthew J.; Christian, James F.; Ward, Brent B.; Vartarian, Mark; Feinberg, Stephen E.; Lee, Seung Yup; Parikh, Urmi; Mycek, Mary-Ann; Joyner, Michael J.; Johnson, Christopher P.; Paradis, Norman A.

    2016-03-01

    Stable, relative localization of source and detection fibers is necessary for clinical implementation of quantitative optical perfusion monitoring methods such as diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy (DRS). A flexible and compact device design is presented as a platform for simultaneous monitoring of perfusion at a range of depths, enabled by precise location of optical fibers in a robust and secure adhesive patch. We will discuss preliminary data collected on human subjects in a lower body negative pressure model for hypovolemic shock. These data indicate that this method facilitates simple and stable simultaneous monitoring of perfusion at multiple depths and within multiple physiological compartments.

  17. The diffusion of ions in unconsolidated sediments

    USGS Publications Warehouse

    Manheim, F. T.

    1970-01-01

    Diffusion in unconsolidated sediments generally proceeds at rates ranging from half to one twentieth of those applying to diffusion of ions and molecules in free solution. Diffusion rates are predictable with respect to porosity and path tortuosity in host sediments, and can be conveniently measured by determinations of electrical resistivity on bulk sediment samples. Net ion flux is further influenced by reactions of diffusing species with enclosing sediments, but such influences should not be confused with or lumped with diffusion processes. ?? 1970.

  18. Regulation of skeletal muscle perfusion during exercise

    NASA Technical Reports Server (NTRS)

    Delp, M. D.; Laughlin, M. H.

    1998-01-01

    For exercise to be sustained, it is essential that adequate blood flow be provided to skeletal muscle. The local vascular control mechanisms involved in regulating muscle perfusion during exercise include metabolic control, endothelium-mediated control, propagated responses, myogenic control, and the muscle pump. The primary determinant of muscle perfusion during sustained exercise is the metabolic rate of the muscle. Metabolites from contracting muscle diffuse to resistance arterioles and act directly to induce vasodilation, or indirectly to inhibit noradrenaline release from sympathetic nerve endings and oppose alpha-adrenoreceptor-mediated vasoconstriction. The vascular endothelium also releases vasodilator substances (e.g., prostacyclin and nitric oxide) that are prominent in establishing basal vascular tone, but these substances do not appear to contribute to the exercise hyperemia in muscle. Endothelial and smooth muscle cells may also be involved in propagating vasodilator signals along arterioles to parent and daughter vessels. Myogenic autoregulation does not appear to be involved in the exercise hyperemia in muscle, but the rhythmic propulsion of blood from skeletal muscle veins facilitates venous return to the heart and muscle perfusion. It appears that the primary determinants of sustained exercise hyperemia in skeletal muscle are metabolic vasodilation and increased vascular conductance via the muscle pump. Additionally, sympathetic neural control is important in regulating muscle blood flow during exercise.

  19. Source confusion as an explanation of cultivation: a test of the mechanisms underlying confusion of fiction with reality on television.

    PubMed

    Koolstra, Cees M

    2007-02-01

    Cultivation studies have found evidence that heavy television viewers adopt a world view congruent with how the world is portrayed in fictional television programs. An explanation is that viewers may remember fictional TV stories as realistic stories or news (fiction-to-news confusion). Until now, fiction-to-news confusion was found only if at least a week evolved between watching TV and asking viewers what was remembered. The present study conducted with a purposive sample of students and employees of a college in The Netherlands (N=96; M age = 28.6 yr., SD = 10.9) indicates that fiction-to-news confusions can also occur almost immediately after watching. In addition, whereas earlier research suggests that fiction-to-news confusions are associated with heavy viewing, i.e., more confusion when more hours per day are spent on TV viewing in leisure time, and faulty memory, the present study more specifically suggests that participants make many fiction-to-news confusions when they are exposed to relatively many fictional TV fragments that contain threatening, violent events. PMID:17450970

  20. Lung Ventilation/Perfusion Scan

    MedlinePlus

    ... from the NHLBI on Twitter. What Is a Lung Ventilation/Perfusion Scan? A lung ventilation/perfusion scan, or VQ scan, is a ... that measures air and blood flow in your lungs. A VQ scan most often is used to ...

  1. Diagnosing acute lacunar infarction using CT perfusion.

    PubMed

    Cao, Wenjie; Yassi, Nawaf; Sharma, Gagan; Yan, Bernard; Desmond, Patricia M; Davis, Stephen M; Campbell, Bruce C V

    2016-07-01

    The value of CT perfusion (CTP) in detecting acute lacunar infarcts (LACI) has not been well established. We tested the sensitivity of CTP for LACI. CTP maps of consecutive stroke patients from 2009-2013 were examined. MRI diffusion imaging was used to identify those with LACI. Two stroke neurologists independently evaluated the CTP maps for evidence of a perfusion lesion in a deep perforating artery territory. Cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) and time to maximum (Tmax) maps were first examined in isolation and then in combination. Inter-observer agreement was measured using Cohen's κ. The lesions identified were later confirmed against the diffusion MRI reference and the sensitivity and specificity of CTP maps calculated. A total of 63 patient scans were analysed. There were 32 patients with MRI-confirmed LACI within the coverage of CTP; 18 in the striatum, 10 thalamic, and four in the corona radiata. Another 31 patients had normal MRI. Inter-rater agreement was good (κ=0.83). Sensitivity (blinded consensus) was highest for MTT (56.2%) compared to Tmax (25%, p<0.001), CBV (9.3%, p=0.021) and CBF (43.7%, p<0.001). MTT maps enable detection of a significant proportion of LACI using CTP. PMID:26899357

  2. (abstract) An All Sky Cirrus Confusion Noise Map for WIRE

    NASA Technical Reports Server (NTRS)

    Gautier, T. N.

    1996-01-01

    The Wide Field Infrared Explorer (WIRE) is a Small Explorer (SMEX) satellite scheduled for launch in 1998 which will carry out a sky survey of at least 100 square degrees in the wavelength regions of 9-15(micro)m and 21-27(micro)m with spatial resolution of approximately 20 arcsec and sensitivity exceeding 0.6mJy. At this sensitivity level WIRE observations can be seriously affected by the confusion noise contribution from the infrared cirrus emission, so the WIRE survey must be planned with some knowledge of the expected level of cirrus confusion. Production of a cirrus confusion noise map with 0.5 degree resolution based on the spatial power spectral density of the cirrus emission in the IRAS ISSA data is in progess using the method described by Gauthier, et al. Spectrally resolved power spectra density data is obtained from the ISSA maps with a wavelet transform technique.

  3. Circle of least confusion of a spherical reflector.

    PubMed

    Hosken, Robert W

    2007-06-01

    A simple, tractable equation is provided for determining the size and location of the circle of least confusion of a concave spherical reflector. This method is exact for the object at infinity and with wave effects neglected. Designers of large radius Arecibo-like telescopes, both radio and optical, with symmetrical, spherical primaries should find the method useful. The mathematical results are valid for apertures with an angle of incidence up to 45 degrees. Comparisons of the location of the disk of least confusion with longitudinal spherical aberration and the radius of the disk with transverse spherical aberration are presented. PMID:17514263

  4. Addressing the Philosophical Confusion Regarding Constructivism in Chemical Education

    NASA Astrophysics Data System (ADS)

    Bernal, Pedro J.

    2006-02-01

    In the Chemical Education Today section of the May 2003 issue of this Journal , Eric Scerri wrote about the consequences of what he regards as a philosophical confusion in the work of constructivist chemical education researchers. This issue has important implications for both the teaching and practice of science. I offer a view of the confusion that places the emphasis on the careless use of philosophical terms that Scerri noted and on the tendency of psychological constructivists to go from psychological premises to unwarranted epistemological conclusions.

  5. Ex vivo lung perfusion.

    PubMed

    Machuca, Tiago N; Cypel, Marcelo

    2014-08-01

    Lung transplantation (LTx) is an established treatment option for eligible patients with end-stage lung disease. Nevertheless, the imbalance between suitable donor lungs available and the increasing number of patients considered for LTx reflects in considerable waitlist mortality. Among potential alternatives to address this issue, ex vivo lung perfusion (EVLP) has emerged as a modern preservation technique that allows for more accurate lung assessment and also improvement of lung function. Its application in high-risk donor lungs has been successful and resulted in safe expansion of the donor pool. This article will: (I) review the technical details of EVLP; (II) the rationale behind the method; (III) report the worldwide clinical experience with the EVLP, including the Toronto technique and others; (IV) finally, discuss the growing literature on EVLP application for donation after cardiac death (DCD) lungs. PMID:25132972

  6. Ex vivo lung perfusion

    PubMed Central

    Machuca, Tiago N.

    2014-01-01

    Lung transplantation (LTx) is an established treatment option for eligible patients with end-stage lung disease. Nevertheless, the imbalance between suitable donor lungs available and the increasing number of patients considered for LTx reflects in considerable waitlist mortality. Among potential alternatives to address this issue, ex vivo lung perfusion (EVLP) has emerged as a modern preservation technique that allows for more accurate lung assessment and also improvement of lung function. Its application in high-risk donor lungs has been successful and resulted in safe expansion of the donor pool. This article will: (I) review the technical details of EVLP; (II) the rationale behind the method; (III) report the worldwide clinical experience with the EVLP, including the Toronto technique and others; (IV) finally, discuss the growing literature on EVLP application for donation after cardiac death (DCD) lungs. PMID:25132972

  7. John Wilson's Confused "Perspectives on the Philosophy of Education"

    ERIC Educational Resources Information Center

    Standish, Paul

    2006-01-01

    In his "Perspectives on the Philosophy of Education" John Wilson laments the confusion that surrounds the current state of the philosophy of education. Unlike other branches of philosophy, he claims, it is not clear what the philosophy of education is about, and a snapshot of current work in the field reveals its lack of coherence. To remedy this…

  8. Remembering Actions: An Analysis of the Sources of Children's Confusions.

    ERIC Educational Resources Information Center

    Foley, Mary Ann; Aman, Christine

    Involving children 7 and 10 years of age, two experiments aimed to clarify the basis of children's confusion about actions they performed and actions they imagined performing. In experiment 1, subjects were assigned to one of three conditions, each involving two different types of tracing exercises. Children traced simple or complex pictures by…

  9. Toxic "ictal" confusion in middle age: treatment with benzodiazepines.

    PubMed Central

    Van Sweden, B

    1985-01-01

    In adult and elderly non-epileptic subjects psychoactive drugs may cause an altered state of consciousness and repetitive irritative EEG discharges. The neurotoxic pathogenesis of this drug-induced confusion and the differentiation from absence status are discussed. Dramatic relief by intravenous benzodiazepines is detailed. Recovery is complete and prognosis is excellent on withdrawal of the offending drug. PMID:2860211

  10. RTI Confusion in the Case Law and the Legal Commentary

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2011-01-01

    This article expresses the position that the current legal commentary and cases do not sufficiently differentiate response to intervention (RTI) from the various forms of general education interventions that preceded it, thus compounding confusion in professional practice as to legally defensible procedures for identifying children as having a…

  11. Confusion in the Periodic Table of the Elements.

    ERIC Educational Resources Information Center

    Fernelius, W. C.; Powell, W. H.

    1982-01-01

    Discusses long (expanded), short (condensed), and pyramidal periodic table formats and documents events leading to a periodic table in which subgroups (families) are designated with the letters A and B, suggesting that this format is confusing for those consulting the table. (JN)

  12. Class and Culture: Sources of Confusion in Educational Sociology

    ERIC Educational Resources Information Center

    Wrigley, Terry

    2013-01-01

    This paper reiterates the centrality of economics (relations of production) in Marxist models of class, while avoiding the crude determinism which results from a neglect of cultural aspects of class formation. It explores the confusion in education and educational sociology arising from non-Marxist conceptions of class which place an exaggerated…

  13. Alleviating the Common Confusion Caused by Polarity in Electrochemistry.

    ERIC Educational Resources Information Center

    Moran, P. J.; Gileadi, E.

    1989-01-01

    Discussed is some of the confusion encountered in electrochemistry due to misunderstandings of sign conventions and simple mathematical errors. Clarified are issues involving emf series, IUPAC sign conventions, calculation of cell potentials, reference electrodes, the polarity of electrodes in electrochemical devices, and overpotential. (CW)

  14. Women, Education and the Law: Vouchers, Tax Credits, & Legal Confusion

    ERIC Educational Resources Information Center

    First, Patricia F.

    2003-01-01

    In early 2003, two distinguished researchers in school law analyzed aspects of the law vis-a-vis vouchers and tax credits and the public schools (McCarthy, 2003; Welner, 2003). The issues were confusing, and the author wondered how educators and the public responded. How can policy makers make reasonable decisions about public education without a…

  15. {sup 99m}Tc radiopharmaceuticals for brain perfusion imaging

    SciTech Connect

    Deutsch, E.; Volkert, W.A.

    1991-12-31

    It is well established that small, neutral, lipophilic technetium complexes can diffuse into the brain and then be trapped intracellularly by a variety of mechanisms. A more detailed understanding of the structural and chemical parameters which promote efficient diffusion into the brain, and which underlie the trapping mechanisms, will be necessary to delineate the clinical relevance of current agents, and to design improved technetium 99 pharmaceuticals. Current technetium 99 brain-perfusion imaging agents do not show ideal characteristics of brain uptake and retention. Furthermore, significant fractions of the technetium 99 complexes are lost between site of injection and the brain. Thus, it is difficult to use these current agents to quantitate regional cerebral blood flow. Nevertheless, these agents are proving extremely valuable for the SPECT evaluation of abnormalities in brain perfusion patients with neurological disorders.

  16. Hydrostatic determinants of cerebral perfusion

    SciTech Connect

    Wagner, E.M.; Traystman, R.J.

    1986-05-01

    We examined the cerebral blood flow response to alterations in perfusion pressure mediated through decreases in mean arterial pressure, increases in cerebrospinal fluid (CSF) pressure, and increases in jugular venous (JV) pressure in 42 pentobarbital anesthetized dogs. Each of these three pressures was independently controlled. Cerebral perfusion pressure was defined as mean arterial pressure minus JV or CSF pressure, depending on which was greater. Mean hemispheric blood flow was measured with the radiolabeled microsphere technique. Despite 30-mm Hg reductions in mean arterial pressure or increases in CSF or JV pressure, CBF did not change as long as the perfusion pressure remained greater than approximately 60 mm Hg. However, whenever perfusion pressure was reduced to an average of 48 mm Hg, cerebral blood flow decreased 27% to 33%. These results demonstrate the capacity of the cerebral vascular bed to respond similarly to changes in the perfusion pressure gradient obtained by decreasing mean arterial pressure, increasing JV pressure or increasing CSF pressure, and thereby support the above definition of cerebral perfusion pressure.

  17. CAD of myocardial perfusion

    NASA Astrophysics Data System (ADS)

    Storm, Corstiaan J.; Slump, Cornelis H.

    2007-03-01

    Our purpose is in the automated evaluation of the physiological relevance of lesions in coronary angiograms. We aim to extract as much as possible quantitative information about the physiological condition of the heart from standard angiographic image sequences. Coronary angiography is still the gold standard for evaluating and diagnosing coronary abnormalities as it is able to locate precisely the coronary artery lesions. The dimensions of the stenosis can be assessed nowadays successfully with image processing based Quantitative Coronary Angiography (QCA) techniques. Our purpose is to assess the clinical relevance of the pertinent stenosis. We therefore analyze the myocardial perfusion as revealed in standard angiographic image sequences. In a Region-of-Interest (ROI) on the angiogram (without an overlaying major blood vessel) the contrast is measured as a function of time (the so-called time-density curve). The required hyperemic state of exercise is induced artificially by the injection of a vasodilator drug e.g. papaverine. In order to minimize motion artifacts we select based on the recorded ECG signal end-diastolic images in both a basal and a hyperemic run in the same projection to position the ROI. We present the development of the algorithms together with results of a small study of 20 patients which have been catheterized following the standard protocol.

  18. Measuring velocity and temperature profile sectional pipeline behind confuser

    NASA Astrophysics Data System (ADS)

    Siažik, Ján; Malcho, Milan; Lenhard, Richard; Novomestský, Marcel

    2016-06-01

    The article deals with the measuring of temperature and velocity profile in area behind confuser in real made scale model of bypass. For proper operation of the equipment it is necessary to know the actual flow in the pipe. Bypasses have wide application and can be also associated with devices for heat recovery, heat exchangers different designs in which may be used in certain circumstances. In the present case, the heat that would otherwise has not been used is used for heating of insulators, and heating the air in the spray-dryer. The measuring principle was verify how the above-mentioned temperature and velocity profile decomposition above confuser on real made scale model.

  19. RESOLVING THE RADIO SOURCE BACKGROUND: DEEPER UNDERSTANDING THROUGH CONFUSION

    SciTech Connect

    Condon, J. J.; Cotton, W. D.; Fomalont, E. B.; Kellermann, K. I.; Miller, N.; Perley, R. A.; Scott, D.; Vernstrom, T.; Wall, J. V.

    2012-10-10

    We used the Karl G. Jansky Very Large Array to image one primary beam area at 3 GHz with 8'' FWHM resolution and 1.0 {mu}Jy beam{sup -1} rms noise near the pointing center. The P(D) distribution from the central 10 arcmin of this confusion-limited image constrains the count of discrete sources in the 1 < S({mu}Jy) < 10 range. At this level, the brightness-weighted differential count S {sup 2} n(S) is converging rapidly, as predicted by evolutionary models in which the faintest radio sources are star-forming galaxies; and Almost-Equal-To 96% of the background originating in galaxies has been resolved into discrete sources. About 63% of the radio background is produced by active galactic nuclei (AGNs), and the remaining 37% comes from star-forming galaxies that obey the far-infrared (FIR)/radio correlation and account for most of the FIR background at {lambda} Almost-Equal-To 160 {mu}m. Our new data confirm that radio sources powered by AGNs and star formation evolve at about the same rate, a result consistent with AGN feedback and the rough correlation of black hole and stellar masses. The confusion at centimeter wavelengths is low enough that neither the planned Square Kilometre Array nor its pathfinder ASKAP EMU survey should be confusion limited, and the ultimate source detection limit imposed by 'natural' confusion is {<=}0.01 {mu}Jy at {nu} = 1.4 GHz. If discrete sources dominate the bright extragalactic background reported by ARCADE 2 at 3.3 GHz, they cannot be located in or near galaxies and most are {<=}0.03 {mu}Jy at 1.4 GHz.

  20. MR Perfusion Imaging in Acute Ischemic Stroke

    PubMed Central

    Copen, William A.; Schaefer, Pamela W.; Wu, Ona

    2011-01-01

    MR perfusion imaging offers the potential for measuring brain perfusion in acute stroke patients, at a time when treatment decisions based upon these measurements may affect outcomes dramatically. Rapid advancements in both acute stroke therapy and perfusion imaging techniques have resulted in continuing redefinition of the role that perfusion imaging should play in patient management. This review first discusses the basic pathophysiology of acute stroke, with specific attention to alterations in the various perfusion-related parameters that can be studied by MR perfusion imaging. Although these parameters are sometimes treated as somewhat interchangeable, they reveal greatly different information about brain perfusion. Therefore, subsequent discussion of the utility of different kinds of perfusion images focuses on the differences between them, as well as important artifacts that can complicate their interpretation. Finally, research on the continually evolving role of MR perfusion imaging in acute stroke care is summarized. PMID:21640299

  1. Detecting Mode Confusion Through Formal Modeling and Analysis

    NASA Technical Reports Server (NTRS)

    Miller, Steven P.; Potts, James N.

    1999-01-01

    Aircraft safety has improved steadily over the last few decades. While much of this improvement can be attributed to the introduction of advanced automation in the cockpit, the growing complexity of these systems also increases the potential for the pilots to become confused about what the automation is doing. This phenomenon, often referred to as mode confusion, has been involved in several accidents involving modern aircraft. This report describes an effort by Rockwell Collins and NASA Langley to identify potential sources of mode confusion through two complementary strategies. The first is to create a clear, executable model of the automation, connect it to a simulation of the flight deck, and use this combination to review of the behavior of the automation and the man-machine interface with the designers, pilots, and experts in human factors. The second strategy is to conduct mathematical analyses of the model by translating it into a formal specification suitable for analysis with automated tools. The approach is illustrated by applying it to a hypothetical, but still realistic, example of the mode logic of a Flight Guidance System.

  2. Computed tomography perfusion imaging in spectacular shrinking deficit.

    PubMed

    Lee, Vivien H; John, Sayona; Mohammad, Yousef; Prabhakaran, Shyam

    2012-02-01

    Spectacular shrinking deficit (SSD) is characterized by abrupt onset of a major hemispheric stroke syndrome, followed by dramatic and rapid improvement. We retrospectively identified patients with SSD diagnosed at our institution between December 1, 2007, and June 30, 2009. We reviewed computed tomography perfusion (CTP) imaging to determine perfusion defect as a measure of initial ischemic penumbra, and magnetic resonance imaging diffusion-weighted imaging (DWI) to determine the final infarct core. Among the 472 consecutive ischemic stroke patients, 126 (27%) presented with major hemispheric ischemic stroke syndrome, defined as National Institutes of Health Stroke Scale score (NIHSS) ≥8 in the territory of the middle cerebral artery (MCA) or internal carotid artery (ICA). Out of these patients, we identified 8 SSD patients with available CTP data. In these 8 patients, the mean time to dramatic recovery was 3.4 hours (range, 0.75-7 hours), and the mean time from onset to CTP was 12.7 hours (range, 3-30 hours). All 8 patients had perfusion abnormalities in portions of the MCA territory (partial MCA territory in 5 patients and complete MCA territory in 3 patients). The mean time from onset to MRI DWI was 15.5 hours (range, 7.9-34 hours). Restricted diffusion was present in all patients in the corresponding MCA distribution. Vascular imaging revealed MCA occlusion in 2 patients. Cervical vascular imaging revealed carotid occlusion in 2 patients and high-grade carotid stenosis in 2 patients. The stroke mechanisms were cardioembolism in 2 patients, large artery in 4 patients, and unknown in 2 patients. Four patients had repeat CTP imaging available that demonstrated eventual resolution of the perfusion defect. SSD is associated with a "shrinking" clinical syndrome and a "shrinking" perfusion pattern on CTP that lags behind clinical recovery. CTP imaging corroborates that a larger territory is at risk in SSD and contributes to better understanding of SSD. PMID:20702113

  3. Self-rated right-left confusability and performance on the Money Road-Map Test.

    PubMed

    Yamashita, Hikari

    2013-09-01

    This study assessed the relationship between self-rated right-left confusability and performance on the Money Road-Map Test (MRMT). Eighty-six undergraduate university students (44 women and 42 men) rated right-left subjective confusability using a questionnaire, and then completed the MRMT. Low- and high-confusability groups were determined using self-rated confusability scores. The high-confusability participants were less accurate and slower than the low-confusability participants in completing the MRMT. Self-confusability ratings significantly correlated with both accuracy scores and completion times on the MRMT. Although, women showed a significantly greater inclination than men to judge themselves as being more prone to confusion in right-left discrimination, the male advantage was not observed in terms of accuracy of response: there was a significant difference only in the completion time on the MRMT. PMID:22965921

  4. Acute subendocardial infarction with diffuse intense Tc-99m PYP uptake and minimal Tl-201 abnormality.

    PubMed

    Taki, J; Taki, S; Ichiyanagi, K; Akashi, Y; Hisada, K

    1992-08-01

    Tc-99m PYP scintigraphy performed on a patient with severe anterior chest pain showed diffuse intense uptake with central decreased activity corresponding to the left ventricular cavity. Tl-201 myocardial perfusion scintigraphy at rest revealed a minimal perfusion abnormality with decreased apical uptake in the lateral view. Because of these findings, diffuse subendocardial infarction was suggested. PMID:1387053

  5. Spectral Confusion for Cosmological Surveys of Redshifted C II Emission

    NASA Astrophysics Data System (ADS)

    Kogut, A.; Dwek, E.; Moseley, S. H.

    2015-06-01

    Far-infrared cooling lines are ubiquitous features in the spectra of star-forming galaxies. Surveys of redshifted fine-structure lines provide a promising new tool to study structure formation and galactic evolution at redshifts including the epoch of reionization as well as the peak of star formation. Unlike neutral hydrogen surveys, where the 21 cm line is the only bright line, surveys of redshifted fine-structure lines suffer from confusion generated by line broadening, spectral overlap of different lines, and the crowding of sources with redshift. We use simulations to investigate the resulting spectral confusion and derive observing parameters to minimize these effects in pencil-beam surveys of redshifted far-IR line emission. We generate simulated spectra of the 17 brightest far-IR lines in galaxies, covering the 150–1300 μm wavelength region corresponding to redshifts 0 < z < 7, and develop a simple iterative algorithm that successfully identifies the 158 μm [C ii] line and other lines. Although the [C ii] line is a principal coolant for the interstellar medium, the assumption that the brightest observed lines in a given line of sight are always [C ii] lines is a poor approximation to the simulated spectra once other lines are included. Blind line identification requires detection of fainter companion lines from the same host galaxies, driving survey sensitivity requirements. The observations require moderate spectral resolution 700 < R < 4000 with angular resolution between 20″ and 10‧, sufficiently narrow to minimize confusion yet sufficiently large to include a statistically meaningful number of sources.

  6. Retrograde heart perfusion: the Langendorff technique of isolated heart perfusion.

    PubMed

    Bell, Robert M; Mocanu, Mihaela M; Yellon, Derek M

    2011-06-01

    In the late 19th century, a number of investigators were working on perfecting isolated heart model, but it was Oscar Langendorff who, in 1895, pioneered the isolated perfused mammalian heart. Since that time, the Langendorff preparation has evolved and provided a wealth of data underpinning our understanding of the fundamental physiology of the heart: its contractile function, coronary blood flow regulation and cardiac metabolism. In more recent times, the procedure has been used to probe pathophysiology of ischaemia/reperfusion and disease states, and with the dawn of molecular biology and genetic manipulation, the Langendorff perfused heart has remained a stalwart tool in the study of the impact upon the physiology of the heart by pharmacological inhibitors and targeted deletion or up-regulation of genes and their impact upon intracellular signalling and adaption to clinically relevant stressful stimuli. We present here the basic structure of the Langendorff system and the fundamental experimental rules which warrant a viable heart preparation. In addition, we discuss the use of the isolated retrograde perfused heart in the model of ischaemia-reperfusion injury ex-vivo, and its applicability to other areas of study. The Langendorff perfusion apparatus is highly adaptable and this is reflected not only in the procedure's longevity but also in the number of different applications to which it has been turned. PMID:21385587

  7. A Formal Methods Approach to the Analysis of Mode Confusion

    NASA Technical Reports Server (NTRS)

    Butler, Ricky W.; Miller, Steven P.; Potts, James N.; Carreno, Victor A.

    2004-01-01

    The goal of the new NASA Aviation Safety Program (AvSP) is to reduce the civil aviation fatal accident rate by 80% in ten years and 90% in twenty years. This program is being driven by the accident data with a focus on the most recent history. Pilot error is the most commonly cited cause for fatal accidents (up to 70%) and obviously must be given major consideration in this program. While the greatest source of pilot error is the loss of situation awareness , mode confusion is increasingly becoming a major contributor as well. The January 30, 1995 issue of Aviation Week lists 184 incidents and accidents involving mode awareness including the Bangalore A320 crash 2/14/90, the Strasbourg A320 crash 1/20/92, the Mulhouse-Habsheim A320 crash 6/26/88, and the Toulouse A330 crash 6/30/94. These incidents and accidents reveal that pilots sometimes become confused about what the cockpit automation is doing. Consequently, human factors research is an obvious investment area. However, even a cursory look at the accident data reveals that the mode confusion problem is much deeper than just training deficiencies and a lack of human-oriented design. This is readily acknowledged by human factors experts. It seems that further progress in human factors must come through a deeper scrutiny of the internals of the automation. It is in this arena that formal methods can contribute. Formal methods refers to the use of techniques from logic and discrete mathematics in the specification, design, and verification of computer systems, both hardware and software. The fundamental goal of formal methods is to capture requirements, designs and implementations in a mathematically based model that can be analyzed in a rigorous manner. Research in formal methods is aimed at automating this analysis as much as possible. By capturing the internal behavior of a flight deck in a rigorous and detailed formal model, the dark corners of a design can be analyzed. This paper will explore how formal

  8. Bilateral basal Xe-133 retention and ventilation/perfusion patterns in mild and subclinical congestive heart failure

    SciTech Connect

    Lee, H.K.; Skarzynski, J.J.; Spadaro, A. )

    1989-12-01

    The Xe-133 ventilation pattern in congestive heart failure (CHF) was assessed using 24 inpatient ventilation/perfusion studies performed to rule out pulmonary embolism. Patients with histories of CHF, myocardial infarction (MI), and cardiomyopathy were included in the study. Frank pulmonary edema, pulmonary embolism, and other known lung diseases such as chronic obstructive lung disease, tumor, and pneumonia were excluded. Fifteen of the 24 patients had abnormal ventilation scans. Twelve of the 15 showed bilateral basal Xe-133 retention on washout; the remaining 3 showed diffuse, posterior regional retention. On perfusion scans, 14 of the 15 abnormal ventilation patients showed evidence of CHF such as inverted perfusion gradient, enlarged cardiac silhouette, or patchy perfusion, and all of them had a history of CHF or cardiac disease. Nine of the 24 patients had normal ventilation scans, including normal washout patterns. Seven of the nine had normal perfusion (p less than 0.01). Four of the nine normal ventilation patients had a history of cardiac disease or CHF but no recent acute MI. Bilateral basal regional Xe-133 retention, coupled with perfusion scan evidence of CHF such as inverted perfusion gradient, enlarged cardiac silhouette, and patchy perfusion pattern, appears to be a sensitive and characteristic ventilation/perfusion finding in mild or subclinical CHF.

  9. Developing a tissue perfusion sensor.

    PubMed

    Harvey, S L R; Parker, K H; O'Hare, D

    2007-01-01

    The development of a electrochemical tissue perfusion sensor is presented. The sensor is a platinum/platinum ring-disc microelectrode that relies on the principle of collector-generator to monitor mass transport within its vicinity. Tissue perfusion is a mass transport mechanism that describes the movement of respiratory gases, nutrients and metabolites in tissue. The sensor's capability of detecting perfusion at the cellular level in a continuous fashion is unique. This sensor will provide insight into the way nutrients and metabolites are transported in tissue especially in cases were perfusion is low such as in wounds or ischemic tissue. We present experimental work for the development and testing of the sensors in vitro. Experimental flow recordings in free steam solutions as well as the flow through tissue-like media are shown. Tests on post operative human tissue are also presented. The sensor's feature such as the continuous recoding capacities, spatial resolution and the measurement range from ml/min to microl/min are highlighted. PMID:18002549

  10. Countering Climate Confusion in the Classroom: New Methods and Initiatives

    NASA Astrophysics Data System (ADS)

    McCaffrey, M.; Berbeco, M.; Reid, A. H.

    2014-12-01

    Politicians and ideologues blocking climate education through legislative manipulation. Free marketeers promoting the teaching of doubt and controversy to head off regulation. Education standards and curricula that skim over, omit, or misrepresent the causes, effects, risks and possible responses to climate change. Teachers who unknowingly foster confusion by presenting "both sides" of a phony scientific controversy. All of these contribute to dramatic differences in the quality and quantity of climate education received by U.S. students. Most U.S. adults and teens fail basic quizzes on energy and climate basics, in large part, because climate science has never been fully accepted as a vital component of a 21st-century science education. Often skipped or skimmed over, human contributions to climate change are sometimes taught as controversy or through debate, perpetuating a climate of confusion in many classrooms. This paper will review recent history of opposition to climate science education, and explore initial findings from a new survey of science teachers on whether, where and how climate change is being taught. It will highlight emerging effective pedagogical practices identified in McCaffrey's Climate Smart & Energy Wise, including the role of new initiatives such as the Next Generation Science Standards and Green Schools, and detail efforts of the Science League of America in countering denial and doubt so that educators can teach consistently and confidently about climate change.

  11. The Cook Mountain problem: Stratigraphic reality and semantic confusion

    SciTech Connect

    Ewing, T.E. |

    1994-12-31

    Historical inconsistency as to what constitutes the Cook Mountain Formation illustrates the semantic confusion resulting from extending surface-derived stratigraphic names into the subsurface without a full understanding of basin architecture. At the surface, the Cook Mountain Formation consists of fossilerous marine shale, glaucony and marl, and marginal-marine sandstone and shale between the nonmarine Sparta Formation sandstones below and the nonmarine Yegua Formation sandstones and lignitic shales above. Fossils are abundant, including the benthic foraminifer Ceratobulimina eximia. As subsurface exploration began, the first occurrence of Ceratobulimina eximia {open_quotes}Cerat{close_quotes} was used as the top of the marine {open_quotes}Cook Mountain Shale{close_quotes} below the Yegua section. Downdip, the overlying Yegua was found to become a sequence of marine shales and marginal-marine sandstones, the lower part of which yielded {open_quotes}Cerat{close_quotes}. Because of this, the lower sandstones were called {open_quotes}Cook Mountain{close_quotes} in many fields. At the Yegua shelf margin, {open_quotes}Cerat{close_quotes} is absent. Different exploration teams have used their own definitions for {open_quotes}Cook Mountain{close_quotes}, leading to substantial confusion.

  12. Auditory versus phonetic accounts of observed confusions between consonant phonemes.

    PubMed

    Soli, S D; Arabie, P

    1979-07-01

    The utility of phonetic features versus acoustic properties for describing perceptual relations among speech sounds was evaluated with a multidimensional scaling analysis of Miller and Nicely's [J. Acoust. Soc. Am. 27, 338-352 (1955)] consonant confusions data. The INDSCAL method and program were employed with the original data log transformed to enhance consistency with the linear INDSCAL model. A four-dimensional solution accounted for 69% of the variance and was best characterized in terms of acoustic properties of the speech signal, viz., temporal relationship of periodicity and burst onset, shape of voiced first formanant transition, shape of voiced second formanant transition, and amount of initial spectral dispersion, rather than in terms of phonetic features. The amplitude and spectral location of acoustic energy specifying each perceptual dimension were found to determine a dimension's perceptual effect as the signal was degraded by masking noise and bandpass filtering. Consequently, the perceptual bases of identification confusions between pairs of syllables were characterized in terms of the shared acoustic properties which remained salient in the degraded speech. Implications of these findings for feature-based accounts of perceptual relationships between phonemes are considered. PMID:489832

  13. Delusional Confusion of Dreaming and Reality in Narcolepsy

    PubMed Central

    Wamsley, Erin; Donjacour, Claire E.H.M.; Scammell, Thomas E.; Lammers, Gert Jan; Stickgold, Robert

    2014-01-01

    Study Objectives: We investigated a generally unappreciated feature of the sleep disorder narcolepsy, in which patients mistake the memory of a dream for a real experience and form sustained delusions about significant events. Design: We interviewed patients with narcolepsy and healthy controls to establish the prevalence of this complaint and identify its predictors. Setting: Academic medical centers in Boston, Massachusetts and Leiden, The Netherlands. Participants: Patients (n = 46) with a diagnosis of narcolepsy with cataplexy, and age-matched healthy healthy controls (n = 41). Interventions: N/A. Measurements and Results: “Dream delusions” were surprisingly common in narcolepsy and were often striking in their severity. As opposed to fleeting hypnagogic and hypnopompic hallucinations of the sleep/wake transition, dream delusions were false memories induced by the experience of a vivid dream, which led to false beliefs that could persist for days or weeks. Conclusions: The delusional confusion of dreamed events with reality is a prominent feature of narcolepsy, and suggests the possibility of source memory deficits in this disorder that have not yet been fully characterized. Citation: Wamsley E; Donjacour CE; Scammell TE; Lammers GJ; Stickgold R. Delusional confusion of dreaming and reality in narcolepsy. SLEEP 2014;37(2):419-422. PMID:24501437

  14. "Matching" ventilation/perfusion images in fat embolization.

    PubMed

    Skarzynski, J J; Slavin, J D; Spencer, R P; Karimeddini, M K

    1986-01-01

    Forty-eight hours after fracture of the tibia and fibula, a 27-year-old man developed the triad of findings noted in the fat embolism syndrome (neurologic changes, respiratory distress, and petechiae). An initially normal chest-x-ray, which progressed to one of bilateral fluffy diffuse infiltrates, aided in making the diagnosis. Ventilation/perfusion lung images were performed at the time of the radiographic changes and showed "matching" defects. Transcapillary passage of lipid breakdown products was considered to be the cause. While all parts of the lung showed reduced ventilation/perfusion, the upper half of the lung fields was affected more prominently, as opposed to emboli of venous origin, which most frequently involve the lung bases. PMID:3943243

  15. Effects of lung ventilation–perfusion and muscle metabolism–perfusion heterogeneities on maximal O2 transport and utilization

    PubMed Central

    Cano, I; Roca, J; Wagner, P D

    2015-01-01

    Previous models of O2 transport and utilization in health considered diffusive exchange of O2 in lung and muscle, but, reasonably, neglected functional heterogeneities in these tissues. However, in disease, disregarding such heterogeneities would not be justified. Here, pulmonary ventilation–perfusion and skeletal muscle metabolism–perfusion mismatching were added to a prior model of only diffusive exchange. Previously ignored O2 exchange in non-exercising tissues was also included. We simulated maximal exercise in (a) healthy subjects at sea level and altitude, and (b) COPD patients at sea level, to assess the separate and combined effects of pulmonary and peripheral functional heterogeneities on overall muscle O2 uptake ( and on mitochondrial (). In healthy subjects at maximal exercise, the combined effects of pulmonary and peripheral heterogeneities reduced arterial () at sea level by 32 mmHg, but muscle by only 122 ml min−1 (–3.5%). At the altitude of Mt Everest, lung and tissue heterogeneity together reduced by less than 1 mmHg and by 32 ml min−1 (–2.4%). Skeletal muscle heterogeneity led to a wide range of potential among muscle regions, a range that becomes narrower as increases, and in regions with a low ratio of metabolic capacity to blood flow, can exceed that of mixed muscle venous blood. For patients with severe COPD, peak was insensitive to substantial changes in the mitochondrial characteristics for O2 consumption or the extent of muscle heterogeneity. This integrative computational model of O2 transport and utilization offers the potential for estimating profiles of both in health and in diseases such as COPD if the extent for both lung ventilation–perfusion and tissue metabolism–perfusion heterogeneity is known. PMID:25640017

  16. [Pleasure and confusion. A footnote to Freud's translations of Mill].

    PubMed

    Molnar, Michael

    2014-01-01

    In 1863 Theodor Gomperz came to England to propose to Helen Taylor Mill, step-daughter of J. S. Mill. For several months he delayed the proposal while studying transcripts of the Philodemus papyri in the Bodleian Library. There a threatening note, supposedly left on his desk, triggered an attack of paranoia. My study of this incident, initially a mere footnote, expanded into an examination of the obscure causes of this attack. The philosophical question of the nature of desire and the researcher's passion to reconstruct a fragmented classical text are related to Gomperz's unfocussed relationship with both Mill and his step-daughter, and his ensuing confusion between reality and fantasy. The incident is considered paradigmatic of the perils of scholarly research, when the desire to possess knowledge becomes entangled with transferential relationships. PMID:24988804

  17. States of confusion: Jurisdictional variation in Australian medicines nomenclature.

    PubMed

    Hope, Denise; King, Michelle

    2015-06-01

    In December 2000, the Galbally Review recommended Australia achieve national uniformity in drugs and poisons legislation. While the Commonwealth Poisons Standard classifies and schedules medicines and poisons, the Australian States and Territories are responsible for regulating the supply of medicines and poisons through individual medicines legislation. In December 2013, this legislation was examined to identify the nomenclature used to describe medicines. The research found considerable variation across jurisdictions in terms of the nomenclature used, in particular the terms used for Schedules in the State and Territory legislation were often inconsistent with each other and the terms used in the Poisons Standard. Of most concern is that the same term may be used to describe different medicines in different jurisdictions, leading to possible confusion for health practitioners working across jurisdictions as is now possible under national registration. It is therefore imperative that national uniformity of drugs and poisons legislation is achieved to facilitate a common practice reference. PMID:26349380

  18. Visualizing confusion matrices for multidimensional signal detection correlational methods

    NASA Astrophysics Data System (ADS)

    Zhou, Yue; Wischgoll, Thomas; Blaha, Leslie M.; Smith, Ross; Vickery, Rhonda J.

    2013-12-01

    Advances in modeling and simulation for General Recognition Theory have produced more data than can be easily visualized using traditional techniques. In this area of psychological modeling, domain experts are struggling to find effective ways to compare large-scale simulation results. This paper describes methods that adapt the web-based D3 visualization framework combined with pre-processing tools to enable domain specialists to more easily interpret their data. The D3 framework utilizes Javascript and scalable vector graphics (SVG) to generate visualizations that can run readily within the web browser for domain specialists. Parallel coordinate plots and heat maps were developed for identification-confusion matrix data, and the results were shown to a GRT expert for an informal evaluation of their utility. There is a clear benefit to model interpretation from these visualizations when researchers need to interpret larger amounts of simulated data.

  19. High levels of confusion for cholesterol awareness campaigns.

    PubMed

    Hall, Danika V

    2008-09-15

    Earlier this year, two industry-sponsored advertising campaigns for cholesterol awareness that target the general public were launched in Australia. These campaigns aimed to alert the public to the risks associated with having high cholesterol and encouraged cholesterol testing for wider groups than those specified by the National Heart Foundation. General practitioners should be aware of the potential for the two campaigns to confuse the general public as to who should be tested, and where. The campaign sponsors (Unilever Australasia and Pfizer) each have the potential to benefit by increased market share for their products, and increased profits. These disease awareness campaigns are examples of what is increasingly being termed "condition branding" by pharmaceutical marketing experts. PMID:18803537

  20. Acute postictal confusion and violence: Two cases with unfortunate outcomes☆

    PubMed Central

    Grant, Arthur C.; Koziorynska, Ewa; Lushbough, Catherine; Maus, Douglas; Mortati, Katherine

    2013-01-01

    Patients with temporal lobe epilepsy (TLE) often have a brief postictal state characterized by confusion and disorientation. Less common postictal behaviors include wandering and violence — both reactive and spontaneous. We describe two male patients with left TLE and unusual postictal states that led to unfortunate outcomes. The first patient's postictal state included an intense urge to peregrinate, as well as reactive violence. When a frightened houseguest prevented the patient from exiting his bedroom during a postictal state, the patient climbed out the window and fell to his death. The second patient's postictal state included menacing posturing, loud exclamation of guttural sounds or profanities, clapping or smacking his hands together, and punching nearby objects. During a postictal state at home, he grabbed a bat and destroyed furnishings. After he had two seizures at work followed by his typical postictal state, he was dismissed because of his perceived threat to coworkers. PMID:25667832

  1. EFFECT OF VENTILATION AND PERFUSION IMBALANCE ON INERT GAS REBREATHING VARIABLES

    EPA Science Inventory

    The effects of ventilation-to-perfusion (Va/Qc) maldistribution within the lungs on measured multiple gas rebreathing variables were studied in 14 dogs. The rebreathing method (using He, C18C, and C2H2) allows for measurements of pulmonary capillary blood flow (Qc), diffusing cap...

  2. Ex vivo lung graft perfusion.

    PubMed

    Briot, Raphaël; Gennai, Stéphane; Maignan, Maxime; Souilamas, Redha; Pison, Christophe

    2016-04-01

    This review proposes an update of the state of the art and the ongoing clinical trials of ex vivo lung perfusion for lung transplantation in patients. Ex vivo lung perfusion techniques (EVLP) can be used to evaluate a lung graft outside of the body. The goal of EVLP is to study the functional status of lung grafts that were first rejected for transplantation because they did not match all criteria for a conventional transplantation. After an EVLP evaluation, some of these lungs may be requalified for a possible transplantation in patients. This article proposes an overview of the developments of EVLP techniques. During EVLP, the perfusion and ventilation of the isolated lung preparation are very progressive in order to avoid oedema due to ischaemia-reperfusion injuries. Lung evaluation is mainly based on gasometric (PaO2/FiO2) and rheological criteria (low pulmonary arterial resistance). Several series of patients transplanted with EVLP evaluated lungs have been recently published with promising results. EVLP preparations also allow a better understanding of the physiopathology and treatments of ischaemia-reperfusion injuries. Organ procurements from "non-heart-beating" donors will probably require a wider application of these ex vivo techniques. The development of semi-automated systems might facilitate the clinical use of EVLP techniques. PMID:26746565

  3. Intestinal perfusion monitoring using photoplethysmography

    NASA Astrophysics Data System (ADS)

    Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Coté, Gerard L.

    2013-08-01

    In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.

  4. Perfusion Angiography of the Foot in Patients with Critical Limb Ischemia: Description of the Technique

    SciTech Connect

    Jens, Sjoerd Marquering, Henk A.; Koelemay, Mark J. W.; Reekers, Jim A.

    2015-02-15

    ObjectiveTo study the feasibility of 2D perfusion imaging in critical limb ischemia (CLI).Methods/ResultsPerfusion angiography is a new technology which was tested in 18 patients with CLI of the foot. A standardized protocol was used with a catheter placed at the mid-part of the popliteal artery, and a total of 9 cc of non-ionic iodinated contrast material was injected at a rate of 3 cc/sec. The technology is based on early cardiology research where iodinated contrast agents were used for imaging of cardiac perfusion. During the first pass of the contrast, there is a significant diffusion of the contrast agents into the interstitial space, particularly for non-ionic and low-molecular-weight compounds.DiscussionThe original angiography data can be used to make a time–density curve, which represents the actual perfusion of the foot in time. Angiographic perfusion imaging is a post-processing modality for which no extra contrast or radiation is needed. With this technique, it is possible to get more information about the perfusion status and microcirculation of the foot. This is a step toward functional imaging in CLI patients.

  5. Ultrasound perfusion signal processing for tumor detection

    NASA Astrophysics Data System (ADS)

    Kim, MinWoo; Abbey, Craig K.; Insana, Michael F.

    2016-04-01

    Enhanced blood perfusion in a tissue mass is an indication of neo-vascularity and a sign of a potential malignancy. Ultrasonic pulsed-Doppler imaging is a preferred modality for noninvasive monitoring of blood flow. However, the weak blood echoes and disorganized slow flow make it difficult to detect perfusion using standard methods without the expense and risk of contrast enhancement. Our research measures the efficiency of conventional power-Doppler (PD) methods at discriminating flow states by comparing measurement performance to that of an ideal discriminator. ROC analysis applied to the experimental results shows that power Doppler methods are just 30-50 % efficient at perfusion flows less than 1ml/min, suggesting an opportunity to improve perfusion assessment through signal processing. A new perfusion estimator is proposed by extending the statistical discriminator approach. We show that 2-D perfusion color imaging may be enhanced using this approach.

  6. Myocardial perfusion imaging using contrast echocardiography.

    PubMed

    Pathan, Faraz; Marwick, Thomas H

    2015-01-01

    Microbubbles are an excellent intravascular tracer, and both the rate of myocardial opacification (analogous to coronary microvascular perfusion) and contrast intensity (analogous to myocardial blood volume) provide unique insights into myocardial perfusion. A strong evidence base has been accumulated to show comparability with nuclear perfusion imaging and incremental diagnostic and prognostic value relative to wall motion analysis. This technique also provides the possibility to measure myocardial perfusion at the bedside. Despite all of these advantages, the technique is complicated, technically challenging, and has failed to scale legislative and financial hurdles. The development of targeted imaging and therapeutic interventions will hopefully rekindle interest in this interesting modality. PMID:25817740

  7. Estimating a regional ventilation-perfusion index

    PubMed Central

    Muller, P A; Li, T; Isaacson, D; Newell, J C; Saulnier, G J; Kao, Tzu-Jen; Ashe, Jeffrey

    2015-01-01

    This is a methods paper, where an approximation to the local ventilation-perfusion ratio is derived. This approximation, called the ventilation-perfusion index since it is not exactly the physiological ventilation-perfusion ratio, is calculated using conductivity reconstructions obtained using electrical impedance tomography. Since computation of the ventilation-perfusion index only requires knowledge of the internal conductivity, any conductivity reconstruction method may be used. The method is explained, and results are presented using conductivities obtained from two EIT systems, one using an iterative method and the other a linearization method. PMID:26006279

  8. Assessment of the kidneys: magnetic resonance angiography, perfusion and diffusion

    PubMed Central

    2011-01-01

    Renal magnetic resonance (MR) imaging has undergone major improvements in the past several years. This review focuses on the technical basics and clinical applications of MR angiography (MRA) with the goal of enabling readers to acquire high-resolution, high quality renal artery MRA. The current role of contrast agents and their safe use in patients with renal impairment is discussed. In addition, an overview of promising techniques on the horizon for renal MR is provided. The clinical value and specific applications of renal MR are critically discussed. PMID:22085467

  9. Ventilation-perfusion matching during exercise

    NASA Technical Reports Server (NTRS)

    Wagner, P. D.

    1992-01-01

    In normal subjects, exercise widens the alveolar-arterial PO2 difference (P[A-a]O2) despite a more uniform topographic distribution of ventilation-perfusion (VA/Q) ratios. While part of the increase in P(A-a)O2 (especially during heavy exercise) is due to diffusion limitation, a considerable amount is caused by an increase in VA/Q mismatch as detected by the multiple inert gas elimination technique. Why this occurs is unknown, but circumstantial evidence suggests it may be related to interstitial pulmonary edema rather than to factors dependent on ventilation, airway gas mixing, airway muscle tone, or pulmonary vascular tone. In patients with lung disease, the gas exchange consequences of exercise are variable. Thus, arterial PO2 may increase, remain the same, or fall. In general, patients with advanced chronic obstructive pulmonary disease (COPD) or interstitial fibrosis who exercise show a fall in PO2. This is usually not due to worsening VA/Q relationships but mostly to the well-known fall in mixed venous PO2, which itself results from a relatively smaller increase in cardiac output than VO2. However, in interstitial fibrosis (but not COPD), there is good evidence that a part of the fall in PO2 on exercise is caused by alveolar-capillary diffusion limitation of O2 transport; in COPD (but not interstitial fibrosis), a frequent additional contributing factor to the hypoxemia of exercise is an inadequate ventilatory response, such that minute ventilation does not rise as much as does CO2 production or O2 uptake, causing arterial PCO2 to increase and PO2 to fall.

  10. Quantification of brain perfusion with tracers retained by the brain

    SciTech Connect

    Pupi, A.; Bacciottini, L.; De Cristofaro, M.T.R.; Formiconi, A.R.; Castagnoli, A.

    1991-12-31

    Almost a decade ago, tracers, labelled with {sup 123}I and {sup 99m}Tc, that are retained by the brain, started to be used for studies of regional brain perfusion (regional cerebral blood flow, rCBF). To date, these tracers have been used for brain perfusion imaging with SPECT in brain disorders as well as for physiological activation protocols. Only seldom, however, have they been used in protocols that quantitatively measure rCBF. Nevertheless, comparative studies with perfusion reference tracers have repeatedly demonstrated that the brain uptake of these brain-retained tracers is correlated to perfusion, the major determinant of the distribution of these tracers in the brain. The brain kinetics of {sup 99m}Tc HMPAO, which is the tracer most commonly used, was described with a two-compartment tissue model. The theoretical approach, which is, in itself, sufficient for modeling quantitative measurements with {sup 99m}Tc HMPAO, initially suggested the possibility of empirically narrowing the distance between the brain`s regional uptake of the tracer and rCBF with a linearization algorithm which uses the cerebellum as the reference region. The value of this empirical method is hampered by the fact that the cerebellum can be involved in cerebrovascular disease (i.e. cerebellar diaschisis) as well as in several other brain disorders (e.g. anxiety, and dementia of the Alzheimer type). It also was proposed that different reference regions (occipital, whole slice, or whole brain) should be selected in relation to the brain disorder under study. However, this approach does not solve the main problem because it does not equip us with a reliable tool to evaluate rCBF with a high predictive value, and, at the same time, to reduce intersubject variability. The solution would be to measure a quantitative parameter which directly reflects rCBF, such as the unidirectional influx constant of the freely diffusible flow-limited tracers. 45 refs., 3 figs., 1 tab.

  11. Objections, confusion among pharmacists threaten access to emergency contraception.

    PubMed

    Cohen, S A

    1999-06-01

    Emergency contraception (EC) involves women taking a high dose of regular oral contraceptives very shortly after unprotected intercourse. Specifically, emergency contraceptive pills (ECPs) can prevent pregnancy if taken within 72 hours of intercourse in cases of known or suspected contraception failure or when no contraception was used. Adherence to this approach is now widely accepted as capable of dramatically contributing toward the reduction of unintended pregnancies and subsequent abortions. However, in the media and in political debates, ECPs are often confused with mifepristone (RU-486), which is clearly an abortion-inducing drug. The misconception that EC is a method of abortion must be corrected. For example, in some cases, pharmacists refuse to fill prescriptions for ECPs, presumably because they believe they are facilitating abortion. Wal-Mart, one of the country's largest drug retailers, has decided to not sell ECPs. A concerted public education effort is needed to make more people both aware and properly informed of EC in the US. Educational efforts targeted to physicians and women over the past several years appear to have already resulted in a marked increase in the knowledge and use of EC nationwide. Those efforts were likely bolstered by the 1998 US Food and Drug Administration approval, for the first time, of an oral contraception regimen to be packaged and marketed in the US specifically for postcoital use. PMID:12295186

  12. Contrast, contours and the confusion effect in dazzle camouflage

    PubMed Central

    Scott-Samuel, Nicholas E.; Cuthill, Innes C.

    2016-01-01

    ‘Motion dazzle camouflage’ is the name for the putative effects of highly conspicuous, often repetitive or complex, patterns on parameters important in prey capture, such as the perception of speed, direction and identity. Research into motion dazzle camouflage is increasing our understanding of the interactions between visual tracking, the confusion effect and defensive coloration. However, there is a paucity of research into the effects of contrast on motion dazzle camouflage: is maximal contrast a prerequisite for effectiveness? If not, this has important implications for our recognition of the phenotype and understanding of the function and mechanisms of potential motion dazzle camouflage patterns. Here we tested human participants' ability to track one moving target among many identical distractors with surface patterns designed to test the influence of these factors. In line with previous evidence, we found that targets with stripes parallel to the object direction of motion were hardest to track. However, reduction in contrast did not significantly influence this result. This finding may bring into question the utility of current definitions of motion dazzle camouflage, and means that some animal patterns, such as aposematic or mimetic stripes, may have previously unrecognized multiple functions. PMID:27493775

  13. Discrete representation of perceptual structure underlying consonant confusions.

    PubMed

    Soli, S D; Arabie, P; Carroll, J D

    1986-03-01

    The perceptual representation of speech is generally assumed to be discrete rather than continuous, pointing to the need for general discrete analytic models to represent observed perceptual similarities among speech sounds. The INDCLUS (INdividual Differences CLUStering) model and algorithm [J.D. Carroll and P. Arabie, Psychometrika 48, 157-169 (1983)] can provide this generality, representing symmetric three-way similarity data (stimuli X stimuli X conditions) as an additive combination of overlapping, and generally not hierarchial, clusters whose weights (which are numerical values gauging the importance of the clusters) vary both as a function of the cluster and condition being considered. INDCLUS was used to obtain a discrete representation of underlying perceptual structure in the Miller and Nicely consonant confusion data [G.A. Miller and P.E. Nicely, J. Acoust. Soc. Am. 27, 338-352 (1955)]. A 14-cluster solution accounted for 82.9% of total variance across the 17 listening conditions. The cluster composition and the variations in cluster weights as a function of stimulus degradation were interpreted in terms of the common and unique perceptual attributes of the consonants within each cluster. Low-pass filtering and noise masking selectively degraded unique attributes, especially the cues for place of articulation, while high-pass filtering degraded both unique and common attributes. The clustering results revealed that perceptual similarities among consonants are accurately modeled by additive combinations of their specific and discrete acoustic attributes whose weights are determined by the nature of the stimulus degradation. PMID:3958325

  14. Coherence, competence, and confusion in narratives of middle childhood.

    PubMed

    Weinstein, Lissa; Shustorovich, Ellen

    2011-01-01

    Middle childhood is a pivotal time in character development during which enduring internal structures are formed. Fiction can offer insights into the cognitive and affective shifts of this developmental phase and how they are transformed in adulthood. While the success of beloved books for latency age children lies in the solutions they offer to the conflict between the pull toward independence and the pull back to the safety of childhood, the enduring stories for adults about children in their middle years can be seen as works of mourning for the relationship with the parents and the childhood self, but more importantly as attempts to transform their experience of middle childhood through the retrospective creation of a coherence that was initially absent. Thematic and structural elements distinguish two groups of stories for adults: the first appears to solve the conflicts of this period by importing adult knowledge and perspective into the narrative of childhood; the second describes the unconscious disorganizing aspects of this period, thereby offering readers a chance to reorganize their own memories, to make a coherent whole out of the fragmented, the confusing, and the unresolved. PMID:26027140

  15. Contrast, contours and the confusion effect in dazzle camouflage.

    PubMed

    Hogan, Benedict G; Scott-Samuel, Nicholas E; Cuthill, Innes C

    2016-07-01

    'Motion dazzle camouflage' is the name for the putative effects of highly conspicuous, often repetitive or complex, patterns on parameters important in prey capture, such as the perception of speed, direction and identity. Research into motion dazzle camouflage is increasing our understanding of the interactions between visual tracking, the confusion effect and defensive coloration. However, there is a paucity of research into the effects of contrast on motion dazzle camouflage: is maximal contrast a prerequisite for effectiveness? If not, this has important implications for our recognition of the phenotype and understanding of the function and mechanisms of potential motion dazzle camouflage patterns. Here we tested human participants' ability to track one moving target among many identical distractors with surface patterns designed to test the influence of these factors. In line with previous evidence, we found that targets with stripes parallel to the object direction of motion were hardest to track. However, reduction in contrast did not significantly influence this result. This finding may bring into question the utility of current definitions of motion dazzle camouflage, and means that some animal patterns, such as aposematic or mimetic stripes, may have previously unrecognized multiple functions. PMID:27493775

  16. Annual Percentage Rate and Annual Effective Rate: Resolving Confusion in Intermediate Accounting Textbooks

    ERIC Educational Resources Information Center

    Vicknair, David; Wright, Jeffrey

    2015-01-01

    Evidence of confusion in intermediate accounting textbooks regarding the annual percentage rate (APR) and annual effective rate (AER) is presented. The APR and AER are briefly discussed in the context of a note payable and correct formulas for computing each is provided. Representative examples of the types of confusion that we found is presented…

  17. The Lost Lamb: A Literature Review on the Confusion of College Students in China

    ERIC Educational Resources Information Center

    Dong, Jianmei; Han, Fubin

    2010-01-01

    With the development of mass higher education in China, confusion--a contradictory state between college students' awareness of employment, learning, morality, and their own behavior and societal requirements--is proving a ubiquitous problem among college students. His confusion has garnered much social attention. In this paper, the origins of…

  18. The Legal Dimension of RTI--Confusion Confirmed: A Response to Walker and Daves

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2012-01-01

    In this issue of "Learning Disability Quarterly" (LDQ), Professors Daves and Walker reply to my earlier LDQ article on confusion in the cases and commentary about the legal dimension of RTI. In this brief rejoinder, I show that their reply confirms rather than resolves the confusion in their original commentary in 2010. This persistent problem…

  19. The Role of Source Confusions in Television's Cultivation of Social Reality Judgments.

    ERIC Educational Resources Information Center

    Mares, Marie-Louise

    1996-01-01

    Examines whether errors in memory (specifically source confusions) contribute to the link between television viewing and social reality judgments. Finds that a manipulation of the visual similarity of the news and fictional programming affected subjects' tendency to make source confusions. (RS)

  20. Visual and Acoustic Confusability of Target Letters and the Word Superiority Effect.

    ERIC Educational Resources Information Center

    Chastain, Garvin; And Others

    The hypothesis that word context reduces visual rather than acoustic confusion between possible targets was tested in a series of experiments. All involved tachistoscopic presentation of letter strings followed by a pattern mask. Data from eight college students showed that target letters that are confusable only visually and acoustically ("b" and…

  1. Long term perfusion system supporting adipogenesis

    PubMed Central

    Abbott, Rosalyn D.; Raja, Waseem K.; Wang, Rebecca Y.; Stinson, Jordan A.; Glettig, Dean L.; Burke, Kelly A.; Kaplan, David L.

    2015-01-01

    Adipose tissue engineered models are needed to enhance our understanding of disease mechanisms and for soft tissue regenerative strategies. Perfusion systems generate more physiologically relevant and sustainable adipose tissue models, however adipocytes have unique properties that make culturing them in a perfusion environment challenging. In this paper we describe the methods involved in the development of two perfusion culture systems (2D and 3D) to test their applicability for long term in vitro adipogenic cultures. It was hypothesized that a silk protein biomaterial scaffold would provide a 3D framework, in combination with perfusion flow, to generate a more physiologically relevant sustainable adipose tissue engineered model than 2D cell culture. Consistent with other studies evaluating 2D and 3D culture systems for adipogenesis we found that both systems successfully model adipogensis, however 3D culture systems were more robust, providing the mechanical structure required to contain the large, fragile adipocytes that were lost in 2D perfused culture systems. 3D perfusion also stimulated greater lipogenesis and lipolysis and resulted in decreased secretion of LDH compared to 2D perfusion. Regardless of culture configuration (2D or 3D) greater glycerol was secreted with the increased nutritional supply provided by perfusion of fresh media. These results are promising for adipose tissue engineering applications including long term cultures for studying disease mechanisms and regenerative approaches, where both acute (days to weeks) and chronic (weeks to months) cultivation are critical for useful insight. PMID:25843606

  2. Confusion: acetaminophen dosing changes based on NO evidence in adults.

    PubMed

    Krenzelok, Edward P; Royal, Mike A

    2012-06-01

    Acetaminophen (paracetamol) plays a vital role in American health care, with in excess of 25 billion doses being used annually as a nonprescription medication. Over 200 million acetaminophen-containing prescriptions, usually in combination with an opioid, are dispensed annually. While acetaminophen is recognized as a safe and effective analgesic and antipyretic, it is also associated with significant morbidity and mortality (hepatotoxicity) if doses in excess of the therapeutic amount are ingested inappropriately. The maximum daily therapeutic dose of 3900-4000 mg was established in separate actions in 1977 and 1988, respectively, via the Food and Drug Administration (FDA) monograph process for nonprescription medications. The FDA has conducted multiple advisory committee meetings to evaluate acetaminophen and its safety profile, and has suggested (but not mandated) a reduction in the maximum daily dosage from 3900-4000 mg to 3000-3250 mg. In 2011, McNeil, the producer of the Tylenol® brand of acetaminophen, voluntarily reduced the maximum daily dose of its 500 mg tablet product to 3000 mg/day, and it has pledged to change the labeling of its 325 mg/tablet product to reflect a maximum of 3250 mg/day. Generic manufacturers have not changed their dosing regimens and they have remained consistent with the established monograph dose. Therefore, confusion will be inevitable as both consumers and health care professionals try to determine the proper therapeutic dose of acetaminophen. Which is the correct dose of acetaminophen: 3000 mg if 500 mg tablets are used, 3250 mg with 325 mg tablets, or 3900 mg when 650 mg arthritis-strength products are used? PMID:22530736

  3. Myocardial perfusion with rubidium-82. III. Theory relating severity of coronary stenosis to perfusion deficit

    SciTech Connect

    Mullani, N.A.

    1984-11-01

    The relation between the quantitative perfusion deficit, as measured by emission computerized tomography, and the severity of coronary artery stenosis is important for the noninvasive clinical evaluation of coronary artery disease in man. Positron emission tomography allows direct noninvasive measurement of myocardial perfusion and quantification of the size of the perfusion defect. Given this important imformation, a mathematical model has been derived to gauge the severity of a coronary stenosis from quantitative perfusion measurements in the normal and poststenotic regions of the heart. The theoretical basis is presented for relating regional myocardial perfusion and regional perfusion resistance to total, coronary blood flow and resistance at normal resting flow and during maximal coronary vasodilation. The concept of perfusion reserve is presented as a clinical measure of the severity of a stenosis.

  4. Investigation of source-detector separation optimization for an implantable perfusion and oxygenation sensor for liver blood vessels

    NASA Astrophysics Data System (ADS)

    Baba, J. S.; Akl, T. J.; Coté, G. L.; Wilson, M. A.; Ericson, M. N.

    2011-03-01

    An implanted system is being developed to monitor transplanted liver health during the critical 7-10 day period posttransplantation. The unit will monitor organ perfusion and oxygen consumption using optically-based probes placed on both the inflow and outflow blood vessels, and on the liver parenchymal surface. Sensing probes are based on a 3- wavelength LED source and a photodiode detector. Sample diffuse reflectance is measured at 735, 805, and 940 nm. To ascertain optimal source-to-photodetector spacing for perfusion measurement in blood vessels, an ex vivo study was conducted. In this work, a dye mixture simulating 80% blood oxygen saturation was developed and perfused through excised porcine arteries while collecting data for various preset probe source-to-photodetector spacings. The results from this study demonstrate a decrease in the optical signal with decreasing LED drive current and a reduction in perfusion index signal with increasing probe spacing. They also reveal a 2- to 4-mm optimal range for blood vessel perfusion probe source-to-photodetector spacing that allows for sufficient perfusion signal modulation depth with maximized signal to noise ratio (SNR). These findings are currently being applied to guide electronic configuration and probe placement for in vivo liver perfusion porcine model studies.

  5. Dependence of Brain Intravoxel Incoherent Motion Perfusion Parameters on the Cardiac Cycle

    PubMed Central

    Federau, Christian; Hagmann, Patric; Maeder, Philippe; Müller, Markus; Meuli, Reto; Stuber, Matthias; O’Brien, Kieran

    2013-01-01

    Measurement of microvascular perfusion with Intravoxel Incoherent Motion (IVIM) MRI is gaining interest. Yet, the physiological influences on the IVIM perfusion parameters (“pseudo-diffusion” coefficient D*, perfusion fraction f, and flow related parameter fD*) remain insufficiently characterized. In this article, we hypothesize that D* and fD*, which depend on blood speed, should vary during the cardiac cycle. We extended the IVIM model to include time dependence of D* = D*(t), and demonstrate in the healthy human brain that both parameters D* and fD* are significantly larger during systole than diastole, while the diffusion coefficient D and f do not vary significantly. The results non-invasively demonstrate the pulsatility of the brain’s microvasculature. PMID:24023649

  6. Wernicke's Encephalopathy Mimicking Acute Onset Stroke Diagnosed by CT Perfusion

    PubMed Central

    Advani, Rajiv; Kurz, Kathinka D.; Kurz, Martin W.

    2014-01-01

    Background. Metabolic syndromes such as Wernicke's encephalopathy may present with a sudden neurological deficit, thus mimicking acute onset stroke. Due to current emphasis on rapid admission and treatment of acute stroke patients, there is a significant risk that these stroke mimics may end up being treated with thrombolysis. Rigorous clinical and radiological skills are necessary to correctly identify such metabolic stroke mimics, in order to avoid doing any harm to these patients due to the unnecessary use of thrombolysis. Patient. A 51-year-old Caucasian male was admitted to our hospital with suspicion of an acute stroke due to sudden onset dysarthria and unilateral facial nerve paresis. Clinical examination revealed confusion and dysconjugate gaze. Computed tomography (CT) including a CT perfusion (CTP) scan revealed bilateral thalamic hyperperfusion. The use of both clinical and radiological findings led to correctly diagnosing Wernicke's encephalopathy. Conclusion. The application of CTP as a standard diagnostic tool in acute stroke patients can improve the detection of stroke mimics caused by metabolic syndromes as shown in our case report. PMID:24716022

  7. Assessment of foot perfusion in patients with a diabetic foot ulcer.

    PubMed

    Forsythe, Rachael O; Hinchliffe, Robert J

    2016-01-01

    Assessment of foot perfusion is a vital step in the management of patients with diabetic foot ulceration, in order to understand the risk of amputation and likelihood of wound healing. Underlying peripheral artery disease is a common finding in patients with foot ulceration and is associated with poor outcomes. Assessment of foot perfusion should therefore focus on identifying the presence of peripheral artery disease and to subsequently estimate the effect this may have on wound healing. Assessment of perfusion can be difficult because of the often complex, diffuse and distal nature of peripheral artery disease in patients with diabetes, as well as poor collateralisation and heavy vascular calcification. Conventional methods of assessing tissue perfusion in the peripheral circulation may be unreliable in patients with diabetes, and it may therefore be difficult to determine the extent to which poor perfusion contributes to foot ulceration. Anatomical data obtained on cross-sectional imaging is important but must be combined with measurements of tissue perfusion (such as transcutaneous oxygen tension) in order to understand the global and regional perfusion deficit present in a patient with diabetic foot ulceration. Ankle-brachial pressure index is routinely used to screen for peripheral artery disease, but its use in patients with diabetes is limited in the presence of neuropathy and medial arterial calcification. Toe pressure index may be more useful because of the relative sparing of pedal arteries from medial calcification but may not always be possible in patients with ulceration. Fluorescence angiography is a non-invasive technique that can provide rapid quantitative information about regional tissue perfusion; capillaroscopy, iontophoresis and hyperspectral imaging may also be useful in assessing physiological perfusion but are not widely available. There may be a future role for specialized perfusion imaging of these patients, including magnetic resonance

  8. TISSUE ENGINEERING PERFUSABLE CANCER MODELS

    PubMed Central

    Fong, E.L.; Santoro, M.; Farach-Carson, M.C.; Kasper, F.K.; Mikos, A.G.

    2014-01-01

    The effect of fluid flow on cancer progression is currently not well understood, highlighting the need for perfused tumor models to close this gap in knowledge. Enabling biological processes at the cellular level to be modeled with high spatiotemporal control, microfluidic tumor models have demonstrated applicability as platforms to study cell-cell interactions, effect of interstitial flow on tumor migration and the role of vascular barrier function. To account for the multi-scale nature of cancer growth and invasion, macroscale models are also necessary. The consideration of fluid dynamics within tumor models at both the micro- and macroscopic levels may greatly improve our ability to more fully mimic the tumor microenvironment. PMID:24634812

  9. Optical modeling toward optimizing monitoring of intestinal perfusion in trauma patients

    SciTech Connect

    Akl, Tony; Wilson, Mark A.; Ericson, Milton Nance; Cote, Gerard L.

    2013-01-01

    Trauma is the number one cause of death for people between the ages 1 and 44 years in the United States. In addition, according to the Centers of Disease Control and Prevention, injury results in over 31 million emergency department visits annually. Minimizing the resuscitation period in major abdominal injuries increases survival rates by correcting impaired tissue oxygen delivery. Optimization of resuscitation requires a monitoring method to determine sufficient tissue oxygenation. Oxygenation can be assessed by determining the adequacy of tissue perfusion. In this work, we present the design of a wireless perfusion and oxygenation sensor based on photoplethysmography. Through optical modeling, the benefit of using the visible wavelengths 470, 525 and 590nm (around the 525nm hemoglobin isobestic point) for intestinal perfusion monitoring is compared to the typical near infrared (NIR) wavelengths (805nm isobestic point) used in such sensors. Specifically, NIR wavelengths penetrate through the thin intestinal wall (~4mm) leading to high background signals. However, these visible wavelengths have two times shorter penetration depth that the NIR wavelengths. Monte-Carlo simulations show that the transmittance of the three selected wavelengths is lower by 5 orders of magnitude depending on the perfusion state. Due to the high absorbance of hemoglobin in the visible range, the perfusion signal carried by diffusely reflected light is also enhanced by an order of magnitude while oxygenation signal levels are maintained. In addition, short source-detector separations proved to be beneficial for limiting the probing depth to the thickness of the intestinal wall.

  10. A spatially-distributed computational model to quantify behaviour of contrast agents in MR perfusion imaging

    PubMed Central

    Cookson, A.N.; Lee, J.; Michler, C.; Chabiniok, R.; Hyde, E.; Nordsletten, D.; Smith, N.P.

    2014-01-01

    Contrast agent enhanced magnetic resonance (MR) perfusion imaging provides an early, non-invasive indication of defects in the coronary circulation. However, the large variation of contrast agent properties, physiological state and imaging protocols means that optimisation of image acquisition is difficult to achieve. This situation motivates the development of a computational framework that, in turn, enables the efficient mapping of this parameter space to provide valuable information for optimisation of perfusion imaging in the clinical context. For this purpose a single-compartment porous medium model of capillary blood flow is developed which is coupled with a scalar transport model, to characterise the behaviour of both blood-pool and freely-diffusive contrast agents characterised by their ability to diffuse through the capillary wall into the extra-cellular space. A parameter space study is performed on the nondimensionalised equations using a 2D model for both healthy and diseased myocardium, examining the sensitivity of system behaviour to Peclet number, Damköhler number (Da), diffusivity ratio and fluid porosity. Assuming a linear MR signal response model, sample concentration time series data are calculated, and the sensitivity of clinically-relevant properties of these signals to the model parameters is quantified. Both upslope and peak values display significant non-monotonic behaviour with regard to the Damköhler number, with these properties showing a high degree of sensitivity in the parameter range relevant to contrast agents currently in use. However, the results suggest that signal upslope is the more robust and discerning metric for perfusion quantification, in particular for correlating with perfusion defect size. Finally, the results were examined in the context of nonlinear signal response, flow quantification via Fermi deconvolution and perfusion reserve index, which demonstrated that there is no single best set of contrast agent parameters

  11. Induction of Hepatic and Endothelial Differentiation by Perfusion in a Three-Dimensional Cell Culture Model of Human Fetal Liver

    PubMed Central

    Pekor, Christopher; Gerlach, Jörg C.; Nettleship, Ian

    2015-01-01

    The development of functional engineered tissue constructs depends on high cell densities and appropriate vascularization. In this study we implemented a four-compartment three-dimensional perfusion bioreactor culture model for studying the effects of medium perfusion on endothelial, hepatic, and hematopoietic cell populations of primary human fetal liver in an in vivo-like environment. Human fetal liver cells were cultured in bioreactors configured to provide either perfusion or diffusion conditions. Metabolic activities of the cultures were monitored daily by measuring glucose consumption and lactate production. Cell viability during culture was analyzed by lactate dehydrogenase activity. Hepatic functionality was determined by the release of albumin and alpha-fetoprotein (AFP) in culture medium samples. After 4 days of culture, cells were analyzed for the expression of a variety of endothelial, hepatic, and hematopoietic genes, as well as the surface marker expression of CD31 and CD34 in flow cytometry. We found that medium perfusion increased the gene expression of endothelial markers such as CD31, von Willebrand factor (vWF), CD140b, CD309, and CD144 while decreasing the gene expression of the erythrocyte-surface marker CD235a. Hepatic differentiation was promoted under perfusion conditions as demonstrated by lower AFP and higher albumin secretion compared with cultures not exposed to medium perfusion. Additionally, cultures exposed to medium perfusion gave higher rates of glucose consumption and lactate production, indicating increased metabolic activity. In conclusion, high-density bioreactors configured to provide constant medium perfusion significantly induced hepatic and endothelial cell differentiation and provided improved conditions for the culture of human fetal liver cells compared with cultures without perfusion. PMID:25559936

  12. Induction of Hepatic and Endothelial Differentiation by Perfusion in a Three-Dimensional Cell Culture Model of Human Fetal Liver.

    PubMed

    Pekor, Christopher; Gerlach, Jörg C; Nettleship, Ian; Schmelzer, Eva

    2015-07-01

    The development of functional engineered tissue constructs depends on high cell densities and appropriate vascularization. In this study we implemented a four-compartment three-dimensional perfusion bioreactor culture model for studying the effects of medium perfusion on endothelial, hepatic, and hematopoietic cell populations of primary human fetal liver in an in vivo-like environment. Human fetal liver cells were cultured in bioreactors configured to provide either perfusion or diffusion conditions. Metabolic activities of the cultures were monitored daily by measuring glucose consumption and lactate production. Cell viability during culture was analyzed by lactate dehydrogenase activity. Hepatic functionality was determined by the release of albumin and alpha-fetoprotein (AFP) in culture medium samples. After 4 days of culture, cells were analyzed for the expression of a variety of endothelial, hepatic, and hematopoietic genes, as well as the surface marker expression of CD31 and CD34 in flow cytometry. We found that medium perfusion increased the gene expression of endothelial markers such as CD31, von Willebrand factor (vWF), CD140b, CD309, and CD144 while decreasing the gene expression of the erythrocyte-surface marker CD235a. Hepatic differentiation was promoted under perfusion conditions as demonstrated by lower AFP and higher albumin secretion compared with cultures not exposed to medium perfusion. Additionally, cultures exposed to medium perfusion gave higher rates of glucose consumption and lactate production, indicating increased metabolic activity. In conclusion, high-density bioreactors configured to provide constant medium perfusion significantly induced hepatic and endothelial cell differentiation and provided improved conditions for the culture of human fetal liver cells compared with cultures without perfusion. PMID:25559936

  13. Ventilation-perfusion imaging in pulmonary papillomatosis

    SciTech Connect

    Espinola, D.; Rupani, H.; Camargo, E.E.; Wagner, H.N. Jr.

    1981-11-01

    Three children with laryngeal papillomas involving the lungs had serial ventilation-perfusion scintigrams to assess results of therapy designed to reduce the bronchial involvement. Different imaging patterns were observed depending on size, number, and location of lesions. In early parenchymal involvement a ventilation-perfusion mismatch was seen. The initial and follow-up studies correlated well with clinical and radiographic findings. This noninvasive procedure is helpful in evaluating ventilatory and perfusion impairment in these patients as well as their response to treatment.

  14. Cochlear perfusion with a viscous fluid.

    PubMed

    Wang, Yi; Olson, Elizabeth S

    2016-07-01

    The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawn from basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner's membrane (RM), while in cochleae perfused with 0.125% and 0.25% HA RM was torn. Thus, the CAP threshold elevation was likely due to the broken RM, likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and

  15. Luminal distension as a possible consequence of experimental intestinal perfusion

    PubMed Central

    Wingate, David; Hyams, Ashley; Phillips, Sidney

    1974-01-01

    In an experimental jejunal perfusion study, distress in healthy subjects occurred during eight out of 16 perfusions in which intestinal secretion was provoked. Calculation demonstrates the volumetric consequences of inadequate recovery of secretory perfusates, and analysis of the perfusion studies shows that distress was significantly associated with poor recovery of the perfusate. These observations are pertinent to increasing interest in the phenomenon of intestinal fluid secretion. PMID:4435588

  16. Perfusion education and training in Europe.

    PubMed

    Merkle, Frank

    2006-01-01

    Perfusion education and training varies considerably throughout Europe. Unlike in the US, where a common curriculum for perfusion education has been established, each European country has its own education system. This fact is further complicated by a multitude of national languages and cultures. Thus, perfusion education programmes vary, not only in content, but also in their academic levels. This article aims to give a comprehensive overview of the situation in each of the 20 member states of the European Board of Cardiovascular Perfusion (EBCP). The EBCP delegates were polled for a description of the process of training and education of clinical perfusionists in their respective countries. Following the initial delegate poll in 2001, an update of the material was performed in spring 2005. In summary, training of clinical perfusionists in Europe varies considerably between countries. A professional body is necessary to oversee the training process and to guarantee a minimum level of clinical competency for cardiovascular perfusionists. PMID:16485693

  17. Uterine perfusion model for analyzing barriers to transport in fibroids.

    PubMed

    Stirland, Darren L; Nichols, Joseph W; Jarboe, Elke; Adelman, Marisa; Dassel, Mark; Janát-Amsbury, Margit-Maria; Bae, You Han

    2015-09-28

    This project uses an ex vivo human perfusion model for studying transport in benign, fibrous tumors. The uterine arteries were cannulated to perfuse the organ with a buffer solution containing blood vessel stain and methylene blue to analyze intratumoral transport. Gross examination revealed tissue expansion effects and a visual lack of methylene blue in the fibroids. Some fibroids exhibited regions with partial methylene blue penetration into the tumor environment. Histological analysis comparing representative sections of fibroids and normal myometrium showed a smaller number of vessels with decreased diameters within the fibroid. Imaging of fluorescently stained vessels exposed a stark contrast between fluorescence within the myometrium and relatively little within the fibroid tissues. Imaging at higher magnification revealed that fibroid blood vessels were indeed perfused and stained with the lipophilic membrane dye; however, the vessels were only the size of small capillaries and the blood vessel coverage was only 12% that of the normal myometrium. The majority of sampled fibroids had a strong negative correlation (Pearson's r=-0.68 or beyond) between collagen and methylene blue staining. As methylene blue was able to passively diffuse into fibroid tissue, the true barrier to transport in these fibroids is likely high interstitial fluid pressure, correlating with high collagen content and solid stress observed in the fibroid tissue. Fibroids had an average elevated interstitial fluid pressure of 4mmHg compared to -1mmHg in normal myometrium. Our findings signify relationships between drug distribution in fibroids and between vasculature characteristics, collagen levels, and interstitial fluid pressure. Understanding these barriers to transport can lead to developments in drug delivery for the treatment of uterine fibroids and tumors of similar composition. PMID:26184049

  18. Myocardial perfusion imaging with 201Tl.

    PubMed

    Pagnanelli, Robert A; Basso, Danny A

    2010-03-01

    The object of this review is to provide information about (201)Tl-thallous chloride in radionuclide myocardial perfusion imaging. This technique has experienced a recent resurgence because of the shortage of (99m)Tc. After reading this article, the technologist will be able to describe the properties and uptake mechanism of (201)Tl, the procedure for myocardial perfusion imaging with this agent, and the advantages and disadvantages of thallium, compared with the technetium agents. PMID:20159930

  19. Improved exercise myocardial perfusion during lidoflazine therapy

    SciTech Connect

    Shapiro, W.; Narahara, K.A.; Park, J.

    1983-11-01

    Lidoflazine is a synthetic drug with calcium-channel blocking effects. In a study of 6 patients with severe classic angina pectoris, single-blind administration of lidoflazine was associated with improved myocardial perfusion during exercise as determined by thallium-201 stress scintigraphy. These studies demonstrate that lidoflazine therapy is associated with relief of angina, an increased physical work capacity, and improved regional myocardial perfusion during exercise.

  20. Methodology for ventilation/perfusion SPECT.

    PubMed

    Bajc, Marika; Neilly, Brian; Miniati, Massimo; Mortensen, Jan; Jonson, Björn

    2010-11-01

    Ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) is the scintigraphic technique of choice for the diagnosis of pulmonary embolism and many other disorders that affect lung function. Data from recent ventilation studies show that the theoretic advantages of Technegas over radiolabeled liquid aerosols are not restricted to the presence of obstructive lung disease. Radiolabeled macroaggregated human albumin is the imaging agent of choice for perfusion scintigraphy. An optimal combination of nuclide activities and acquisition times for ventilation and perfusion, collimators, and imaging matrix yields an adequate V/Q SPECT study in approximately 20 minutes of imaging time. The recommended protocol based on the patient remaining in an unchanged position during the initial ventilation study and the perfusion study allows presentation of matching ventilation and perfusion slices in all projections as well as in rotating volume images based upon maximum intensity projections. Probabilistic interpretation of V/Q SPECT should be replaced by a holistic interpretation strategy on the basis of all relevant information about the patient and all ventilation/perfusion patterns. PE is diagnosed when there is more than one subsegment showing a V/Q mismatch representing an anatomic lung unit. Apart from pulmonary embolism, other pathologies should be identified and reported, for example, obstructive disease, heart failure, and pneumonia. Pitfalls exist both with respect to imaging technique and scan interpretation. PMID:20920632

  1. Experiences with the magnetism of conducting loops: Historical instruments, experimental replications, and productive confusions

    NASA Astrophysics Data System (ADS)

    Cavicchi, Elizabeth

    2003-02-01

    This study investigates nineteenth century laboratory work on electromagnetism through historical accounts and experimental replications. Oersted found that when a magnetic needle was placed in varying positions around a conducting wire, its orientation changed: in moving from a spot above the wire to one below, its sense inverted. This behavior was confusing and provocative. Early experimenters such as Johann Schweigger, Johann Poggendorff, and James Cumming engaged it by bending wire into loops. These loops, which increased the magnetic effect on a compass placed within, also provided evidence of their understanding and confusion. Coiling conducting wires around iron magnetized it, but when some wires coiled oppositely from others, the effect diminished. This effect confused contemporaries of Joseph Henry who made electromagnets, and amateurs later in the century who constructed multisection induction coils. I experienced these confusions myself while working with multilayer coils and induction coils that I made to replicate the historical instruments. This study shows how confusion can be a productive element in learning, by engaging learners to ask questions and invent experiments. By providing space for learners' confusions, teachers can support the development of their students' physical understandings.

  2. Gravitational-wave confusion background from cosmological compact binaries: Implications for future terrestrial detectors

    NASA Astrophysics Data System (ADS)

    Regimbau, T.; Hughes, Scott A.

    2009-03-01

    Increasing the sensitivity of a gravitational-wave (GW) detector improves our ability to measure the characteristics of detected sources. It also increases the number of weak signals that contribute to the data. Because GW detectors have nearly all-sky sensitivity, they can be subject to a confusion limit: Many sources which cannot be distinguished may be measured simultaneously, defining a stochastic noise floor to the sensitivity. For GW detectors operating at present and for their planned upgrades, the projected event rate is sufficiently low that we are far from the confusion-limited regime. However, some detectors currently under discussion may have large enough reach to binary inspiral that they enter the confusion-limited regime. In this paper, we examine the binary inspiral confusion limit for terrestrial detectors. We consider a broad range of inspiral rates in the literature, several planned advanced gravitational-wave detectors, and the highly advanced “Einstein telescope” design. Though most advanced detectors will not be impacted by this limit, the Einstein telescope with a very low-frequency “seismic wall” may be subject to confusion noise. At a minimum, careful data analysis will be require to separate signals which will appear confused. This result should be borne in mind when designing highly advanced future instruments.

  3. The relationship between magical thinking, inferential confusion and obsessive-compulsive symptoms.

    PubMed

    Goods, N A R; Rees, C S; Egan, S J; Kane, R T

    2014-01-01

    Inferential confusion is an under-researched faulty reasoning process in obsessive-compulsive disorder (OCD). Based on an overreliance on imagined possibilities, it shares similarities with the extensively researched construct of thought-action fusion (TAF). While TAF has been proposed as a specific subset of the broader construct of magical thinking, the relationship between inferential confusion and magical thinking is unexplored. The present study investigated this relationship, and hypothesised that magical thinking would partially mediate the relationship between inferential confusion and obsessive-compulsive symptoms. A non-clinical sample of 201 participants (M = 34.94, SD = 15.88) were recruited via convenience sampling. Regression analyses found the hypothesised mediating relationship was supported, as magical thinking did partially mediate the relationship between inferential confusion and OC symptoms. Interestingly, inferential confusion had the stronger relationship with OC symptoms in comparison to the other predictor variables. Results suggest that inferential confusion can both directly and indirectly (via magical thinking) impact on OC symptoms. Future studies with clinical samples should further investigate these constructs to determine whether similar patterns emerge, as this may eventually inform which cognitive errors to target in treatment of OCD. PMID:25265223

  4. Hypothermic machine perfusion of the liver and the critical balance between perfusion pressures and endothelial injury.

    PubMed

    't Hart, N A; van der Plaats, A; Leuvenink, H G D; van Goor, H; Wiersema-Buist, J; Verkerke, G J; Rakhorst, G; Ploeg, R J

    2005-01-01

    Hypothermic machine perfusion (HMP) provides better protection against cold ischemic injury than cold storage in marginal donor kidneys. Also, in liver transplantation a switch from static cold storage to HMP could be beneficial as it would allow longer preservation times and the use of marginal donors. A critical question concerning application of HMP in liver preservation is the crucial balance between perfusion pressure and occurrence of endothelial injury. Rat livers were cold-perfused for 24 hours to study perfusion pressures for both hepatic artery and portal vein. Cold storage served as control and was compared to HMP-preserved livers using a mean arterial perfusion pressure of 25 mm Hg and a portal perfusion pressure of 4 mm Hg (25% of normothermic liver circulation) and to HMP at 50 mm Hg and 8 mm Hg perfusion, respectively (50% of normothermic liver circulation). UW solution was enriched with 14.9 micromol/L propidium iodide (PI) to stain for dead cells and with an additional 13.5 micromol/L acridine orange to stain for viable hepatocytes. A low PI-positive cell count was found using HMP at 25% of normal circulation compared to cold storage. The PI count was high for the HMP group perfused at just 50% of normal circulation compared to HMP at 25% and compared to cold storage. In summary, for liver HMP, perfusion at 25% showed complete perfusion with minimal cellular injury. HMP using perfusion pressures of 25 mm Hg for the hepatic artery and 4 mm Hg for the portal vein is feasible without induction of endothelial injury. PMID:15808634

  5. Perfusion measures from dynamic ICG scanning laser ophthalmoscopy

    NASA Astrophysics Data System (ADS)

    Larkin, Sean; Invernizzi, Alessandro; Beecher, David; Staurenghi, Giovanni; Holmes, Tim

    2010-02-01

    Movies acquired from fundus imaging using Indocyanine Green (ICG) and a scanning laser ophthalmoscope provide information for identifying vascular and other retinal abnormalities. Today, the main limitation of this modality is that it requires esoteric training for interpretation. A straightforward interpretation of these movies by objective measurements would aid in eliminating this training barrier. A software program has been developed and tested that produces and visualizes 2D maps of perfusion measures. The program corrects for frame-to-frame misalignment caused by eye motion, including rigid misalignment and warp. The alignment method uses a cross-correlation operation that automatically detects the distance due to motion between adjacent frames. The d-ICG movie is further corrected by removing flicker and vignetting artifacts. Each pixel in the corrected movie sequence is fit with a least-squares spline to yield a smooth intensity temporal profile. From the dynamics of these intensity curves, several perfusion measures are calculated. The most effective of these measures include a metric that represents the amount of time required for a vessel to fill with dye, a metric that represents the diffusion of dye, and a metric that is affected by local blood volume. These metrics are calculated from movies acquired before and after treatment for a neovascular condition. A comparison of these before and after measures may someday provide information to the clinician that helps them to evaluate disease progression and response to treatment.

  6. Tissue Thermal Property Reconstruction by Stopping Heating And Perfusion

    NASA Astrophysics Data System (ADS)

    Sumi, C.; Uchida, T.; Ooba, T.; Inoue, K.

    In this paper, we report robust noninvasive techniques for reconstructing the thermal properties of living tissues, such as thermal conductivity, thermal capacity and thermal diffusivity, for the diagnosis, monitoring and planning of thermal treatments such as high-intensity focus ultrasound (HIFU). Internal tissue temperature distributions can be measured using ultrasonic imaging or magnetic resonance imaging. Provided that the reference thermal properties of living tissues are given in the region of interest (ROI) as initial conditions, we can determine thermal property distributions by solving bioheat transfer equations as simultaneous first-order partial differential equations having temperature distributions as inhomogeneous coefficients. By using the reported technique, the perfusion by blood flow and thermal sources or sinks can also be reconstructed. However, in this study, we perform reconstruction after stopping heating and perfusion; only the thermal properties of living tissues can be reconstructed under such conditions. Simulations were conducted to verify the feasibility of the reconstruction. A minimally invasive thermal treatment will be realized by using our proposed reconstruction technique.

  7. Brain perfusion in acute and chronic hyperglycemia in rats

    SciTech Connect

    Kikano, G.E.; LaManna, J.C.; Harik, S.I. )

    1989-08-01

    Recent studies show that acute and chronic hyperglycemia cause a diffuse decrease in regional cerebral blood flow and that chronic hyperglycemia decreases the brain L-glucose space. Since these changes can be caused by a decreased density of perfused brain capillaries, we used 30 adult male Wistar rats to study the effect of acute and chronic hyperglycemia on (1) the brain intravascular space using radioiodinated albumin, (2) the anatomic density of brain capillaries using alkaline phosphatase histochemistry, and (3) the fraction of brain capillaries that are perfused using the fluorescein isothiocyanate-dextran method. Our results indicate that acute and chronic hyperglycemia do not affect the brain intravascular space nor the anatomic density of brain capillaries. Also, there were no differences in capillary recruitment among normoglycemic, acutely hyperglycemic, and chronically hyperglycemic rats. These results suggest that the shrinkage of the brain L-glucose space in chronic hyperglycemia is more likely due to changes in the blood-brain barrier permeability to L-glucose.

  8. Noninvasive cerebral perfusion imaging in high-risk neonates.

    PubMed

    Goff, Donna A; Buckley, Erin M; Durduran, Turgut; Wang, Jiongjong; Licht, Daniel J

    2010-02-01

    Advances in medical and surgical care of the high-risk neonate have led to increased survival. A significant number of these neonates suffer from neurodevelopmental delays and failure in school. The focus of clinical research has shifted to understanding events contributing to neurological morbidity in these patients. Assessing changes in cerebral oxygenation and regulation of cerebral blood flow (CBF) is important in evaluating the status of the central nervous system. Traditional CBF imaging methods fail for both ethical and logistical reasons. Optical near infrared spectroscopy (NIRS) is increasingly being used for bedside monitoring of cerebral oxygenation and blood volume in both very low birth weight infants and neonates with congenital heart disease. Although trends in CBF may be inferred from changes in cerebral oxygenation and/or blood volume, NIRS does not allow a direct measure of CBF in these populations. Two relatively new modalities, arterial spin-labeled perfusion magnetic resonance imaging and optical diffuse correlation spectroscopy, provide direct, noninvasive measures of cerebral perfusion suitable for the high-risk neonates. Herein we discuss the instrumentation, applications, and limitations of these noninvasive imaging techniques for measuring and/or monitoring CBF. PMID:20109972

  9. [Pulmonary ventilation/perfusion ratio].

    PubMed

    Guenard, H

    1987-01-01

    The ratios of ventilatory (V) and perfusion (Q) flow rates in the lung are to a large extent responsible for the efficiency of gas exchange. In a simplified monocompartmental model of the lung, the arterial partial pressure of a given gas (Pa) is a function of several factors: the solubility of this gas in blood, its venous and inspired partial pressures and the V/Q ratio. In a multicompartemental model, the mean arterial partial pressure of the gas is a function of the individual values of Pa in each compartment as well as the distribution of V/Q ratios in the lung and the relationship between the concentration and the partial pressure of the gas. The heterogeneity of the distribution of V/Q results from those of both V and Q. Two factors are mainly responsible for this heterogeneity: the gravity and the morphometric characteristics of bronchi and vessels. V/Q ratios are partially controlled at least in low V/Q compartments since hypoxia in these compartments leads to pulmonary arteriolar vasoconstriction. However lungs V/Q ratios range from 0.1 to 10 with a mode around 1. Age, muscular exercise, posture, accelerations, anesthesia, O2 breathing, pulmonary pathology are factors which may alter the distribution of V/Q ratios. PMID:3332289

  10. Fluorescence-based enhanced reality (FLER) for real-time estimation of bowel perfusion in minimally invasive surgery

    NASA Astrophysics Data System (ADS)

    Diana, Michele

    2016-03-01

    Pre-anastomotic bowel perfusion is a key factor for a successful healing process. Clinical judgment has limited accuracy to evaluate intestinal microperfusion. Fluorescence videography is a promising tool for image-guided intraoperative assessment of the bowel perfusion at the future anastomotic site in the setting of minimally invasive procedures. The standard configuration for fluorescence videography includes a Near-Infrared endoscope able to detect the signal emitted by a fluorescent dye, more frequently Indocyanine Green (ICG), which is administered by intravenous injection. Fluorescence intensity is proportional to the amount of fluorescent dye diffusing in the tissue and consequently is a surrogate marker of tissue perfusion. However, fluorescence intensity alone remains a subjective approach and an integrated computer-based analysis of the over-time evolution of the fluorescence signal is required to obtain quantitative data. We have developed a solution integrating computer-based analysis for intra-operative evaluation of the optimal resection site, based on the bowel perfusion as determined by the dynamic fluorescence intensity. The software can generate a "virtual perfusion cartography", based on the "fluorescence time-to-peak". The virtual perfusion cartography can be overlapped onto real-time laparoscopic images to obtain the Enhanced Reality effect. We have defined this approach FLuorescence-based Enhanced Reality (FLER). This manuscript describes the stepwise development of the FLER concept.

  11. Effects of Steroid Hormones on Sex Differences in Cerebral Perfusion

    PubMed Central

    Ghisleni, Carmen; Bollmann, Steffen; Biason-Lauber, Anna; Poil, Simon-Shlomo; Brandeis, Daniel; Martin, Ernst; Michels, Lars; Hersberger, Martin; Suckling, John

    2015-01-01

    Sex differences in the brain appear to play an important role in the prevalence and progression of various neuropsychiatric disorders, but to date little is known about the cerebral mechanisms underlying these differences. One widely reported finding is that women demonstrate higher cerebral perfusion than men, but the underlying cause of this difference in perfusion is not known. This study investigated the putative role of steroid hormones such as oestradiol, testosterone, and dehydroepiandrosterone sulphate (DHEAS) as underlying factors influencing cerebral perfusion. We acquired arterial spin labelling perfusion images of 36 healthy adult subjects (16 men, 20 women). Analyses on average whole brain perfusion levels included a multiple regression analysis to test for the relative impact of each hormone on the global perfusion. Additionally, voxel-based analyses were performed to investigate the sex difference in regional perfusion as well as the correlations between local perfusion and serum oestradiol, testosterone, and DHEAS concentrations. Our results replicated the known sex difference in perfusion, with women showing significantly higher global and regional perfusion. For the global perfusion, DHEAS was the only significant predictor amongst the steroid hormones, showing a strong negative correlation with cerebral perfusion. The voxel-based analyses revealed modest sex-dependent correlations between local perfusion and testosterone, in addition to a strong modulatory effect of DHEAS in cortical, subcortical, and cerebellar regions. We conclude that DHEAS in particular may play an important role as an underlying factor driving the difference in cerebral perfusion between men and women. PMID:26356576

  12. GPU-accelerated voxelwise hepatic perfusion quantification.

    PubMed

    Wang, H; Cao, Y

    2012-09-01

    Voxelwise quantification of hepatic perfusion parameters from dynamic contrast enhanced (DCE) imaging greatly contributes to assessment of liver function in response to radiation therapy. However, the efficiency of the estimation of hepatic perfusion parameters voxel-by-voxel in the whole liver using a dual-input single-compartment model requires substantial improvement for routine clinical applications. In this paper, we utilize the parallel computation power of a graphics processing unit (GPU) to accelerate the computation, while maintaining the same accuracy as the conventional method. Using compute unified device architecture-GPU, the hepatic perfusion computations over multiple voxels are run across the GPU blocks concurrently but independently. At each voxel, nonlinear least-squares fitting the time series of the liver DCE data to the compartmental model is distributed to multiple threads in a block, and the computations of different time points are performed simultaneously and synchronically. An efficient fast Fourier transform in a block is also developed for the convolution computation in the model. The GPU computations of the voxel-by-voxel hepatic perfusion images are compared with ones by the CPU using the simulated DCE data and the experimental DCE MR images from patients. The computation speed is improved by 30 times using a NVIDIA Tesla C2050 GPU compared to a 2.67 GHz Intel Xeon CPU processor. To obtain liver perfusion maps with 626 400 voxels in a patient's liver, it takes 0.9 min with the GPU-accelerated voxelwise computation, compared to 110 min with the CPU, while both methods result in perfusion parameters differences less than 10(-6). The method will be useful for generating liver perfusion images in clinical settings. PMID:22892645

  13. FATTY ACID CHAIN-ELONGATION IN PERFUSED RAT HEART: SYNTHESIS OF STEAROYLCARNITINE FROM PERFUSED PALMITATE

    PubMed Central

    Kerner, Janos; Minkler, Paul E.; Lesnefsky, Edward J.; Hoppel, Charles L.

    2009-01-01

    Rat hearts perfused for up to 60 min in the working mode with palmitate, but not with glucose, resulted in substantial formation of palmitoylcarnitine and stearoylcarnitine. To test whether lipolysis of endogenous lipids was responsible for the increased stearoylcarnitine content or whether some of the perfused palmitate underwent chain elongation, hearts were perfused with hexadecanoic-16,16,16-d3 acid (M+3). The pentafluorophenacyl ester of deuterium labeled stearoylcarnitine had an M+3 (639.4 m/z) compared to the unlabeled M+0 (636.3 m/z) consistent with a direct chain elongation of the perfused palmitate. Furthermore, the near equal isotope enrichment of palmitoyl- (90.2 ± 5.8 %) and stearoylcarnitine (78.0 ± 7.1 %) suggest that both palmitoyl- and stearoyl-CoA have ready access to mitochondrial carnitine palmitoyltransferase and that most of the stearoylcarnitine is derived from the perfused palmitate. PMID:17761175

  14. Pulmonary perfusion during anesthesia and mechanical ventilation.

    PubMed

    Hedenstierna, G

    2005-06-01

    Cardiac output and the pulmonary perfusion can be affected by anesthesia and by mechanical ventilation. The changes contribute to impeded oxygenation of the blood. The major determinant of perfusion distribution in the lung is the relation between alveolar and pulmonary capillary pressures. Perfusion increases down the lung, due to hydrostatic forces. Since atelectasis is located in dependent lung regions, perfusion of non-ventilated lung parenchyma is common, producing shunt of around 8-10% of cardiac output. In addition, non-gravitational inhomogeneity of perfusion, that can be greater than the gravitational inhomogeneity, adds to impeded oxygenation of blood. Essentially all anaesthetics exert some, although mild, cardiodepressant action with one exception, ketamine. Ketamine may also increase pulmonary artery pressure, whereas other agents have little effect on pulmonary vascular tone. Mechanical ventilation impedes venous return and pushes blood flow downwards to dependent lung regions, and the effect may be striking with higher levels of PEEP. During one-lung anesthesia, there is shunt blood flow both in the non-ventilated and the ventilated lung, and shunt can be much larger in the ventilated lung than thought of. Recruitment manoeuvres shall be directed to the ventilated lung and other physical and pharmacological measures can be taken to manipulate blood flow in one lung anesthesia. PMID:15886595

  15. Perfusion harmonic imaging of the human brain

    NASA Astrophysics Data System (ADS)

    Metzler, Volker H.; Seidel, Guenter; Wiesmann, Martin; Meyer, Karsten; Aach, Til

    2003-05-01

    The fast visualisation of cerebral microcirculation supports diagnosis of acute cerebrovascular diseases. However, the commonly used CT/MRI-based methods are time consuming and, moreover, costly. Therefore we propose an alternative approach to brain perfusion imaging by means of ultrasonography. In spite of the low signal/noise-ratio of transcranial ultrasound and the high impedance of the skull, flow images of cerebral blood flow can be derived by capturing the kinetics of appropriate contrast agents by harmonic ultrasound image sequences. In this paper we propose three different methods for human brain perfusion imaging, each of which yielding flow images indicating the status of the patient's cerebral microcirculation by visualising local flow parameters. Bolus harmonic imaging (BHI) displays the flow kinetics of bolus injections, while replenishment (RHI) and diminution harmonic imaging (DHI) compute flow characteristics from contrast agent continuous infusions. RHI measures the contrast agents kinetics in the influx phase and DHI displays the diminution kinetics of the contrast agent acquired from the decay phase. In clinical studies, BHI- and RHI-parameter images were found to represent comprehensive and reproducible distributions of physiological cerebral blood flow. For DHI it is shown, that bubble destruction and hence perfusion phenomena principally can be displayed. Generally, perfusion harmonic imaging enables reliable and fast bedside imaging of human brain perfusion. Due to its cost efficiency it complements cerebrovascular diagnostics by established CT/MRI-based methods.

  16. Radionuclide cerebral perfusion imaging: Normal pattern

    SciTech Connect

    Goldsmith, S.J.; Stritzke, P.; Losonczy, M.; Vallabhajosula, S.; Holan, V.; DaCosta, M.; Muzinic, M.

    1991-12-31

    Regional cerebral perfusion imaging using a new class of {sup 99m}Tc and {sup 123}I labeled compounds which traverse the blood brain barrier and SPECT imaging technology provides an opportunity to assess this physiologic phenomenon during normal cerebral function and as a manifestation of disease in the central nervous system disease. These applications pose a challenge to the nuclear medicine physician for several reasons: (a) the complex and somewhat unfamiliar functional anatomy, (b) the marked regional differences in regional cerebral perfusion at rest, (c) the lack of understanding of the effect of variations in ambient conditions on regional cerebral perfusion. The difficulties in interpretation are augmented by the display itself. There is frequently no difficulty in differentiating between gray and white matter. However, the frequently used {open_quotes}hot body{close_quotes} color maps, introduce a good deal of contrast, producing displays with apparent interruption in regional cortical perfusion whereas black and white displays provide minimal contrast in the regional cortical activity. The authors sought to define how much variation in regional cerebral perfusion is {open_quotes}allowed{close_quotes} under controlled conditions, to establish a basis to interpret if changes in the environment, psychological interventions, or disease states are accompanied by a measurable change. 2 figs., 1 tab.

  17. Spectroscopic confusion: its impact on current and future extragalactic H I surveys

    NASA Astrophysics Data System (ADS)

    Jones, Michael G.; Papastergis, Emmanouil; Haynes, Martha P.; Giovanelli, Riccardo

    2015-05-01

    We present a comprehensive model to predict the rate of spectroscopic confusion in H I surveys, and demonstrate good agreement with the observable confusion in existing surveys. Generically the action of confusion on the H I mass function was found to be a suppression of the number count of sources below the `knee', and an enhancement above it. This results in a bias, whereby the `knee' mass is increased and the faint end slope is steepened. For ALFALFA and HIPASS, we find that the maximum impact this bias can have on the Schechter fit parameters is similar in magnitude to the published random errors. On the other hand, the impact of confusion on the H I mass functions of upcoming medium depth interferometric surveys, will be below the level of the random errors. In addition, we find that previous estimates of the number of detections for upcoming surveys with Square Kilometre Array-precursor telescopes may have been too optimistic, as the framework implemented here results in number counts between 60 and 75 per cent of those previously predicted, while accurately reproducing the counts of existing surveys. Finally, we argue that any future single dish, wide area surveys of H I galaxies would be best suited to focus on deep observations of the local Universe (z < 0.05), as confusion may prevent them from being competitive with interferometric surveys at higher redshift, while their lower angular resolution allows their completeness to be more easily calibrated for nearby extended sources.

  18. A NOVEL TECHNIQUE TO IMPROVE PHOTOMETRY IN CONFUSED IMAGES USING GRAPHS AND BAYESIAN PRIORS

    SciTech Connect

    Safarzadeh, Mohammadtaher; Ferguson, Henry C.; Lu, Yu; Inami, Hanae; Somerville, Rachel S.

    2015-01-10

    We present a new technique for overcoming confusion noise in deep far-infrared Herschel space telescope images making use of prior information from shorter λ < 2 μm wavelengths. For the deepest images obtained by Herschel, the flux limit due to source confusion is about a factor of three brighter than the flux limit due to instrumental noise and (smooth) sky background. We have investigated the possibility of de-confusing simulated Herschel PACS 160 μm images by using strong Bayesian priors on the positions and weak priors on the flux of sources. We find the blended sources and group them together and simultaneously fit their fluxes. We derive the posterior probability distribution function of fluxes subject to these priors through Monte Carlo Markov Chain (MCMC) sampling by fitting the image. Assuming we can predict the FIR flux of sources based on the ultraviolet-optical part of their SEDs to within an order of magnitude, the simulations show that we can obtain reliable fluxes and uncertainties at least a factor of three fainter than the confusion noise limit of 3σ {sub c} = 2.7 mJy in our simulated PACS-160 image. This technique could in principle be used to mitigate the effects of source confusion in any situation where one has prior information of positions and plausible fluxes of blended sources. For Herschel, application of this technique will improve our ability to constrain the dust content in normal galaxies at high redshift.

  19. In vivo perfusion assessment of an anastomosis surgery on porcine intestinal model (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Le, Hanh N. D.; Opferman, Justin; Decker, Ryan; Cheon, Gyeong W.; Kim, Peter C. W.; Kang, Jin U.; Krieger, Axel

    2016-04-01

    Anastomosis, the connection of two structures, is a critical procedure for reconstructive surgery with over 1 million cases/year for visceral indication alone. However, complication rates such as strictures and leakage affect up to 19% of cases for colorectal anastomoses and up to 30% for visceral transplantation anastomoses. Local ischemia plays a critical role in anastomotic complications, making blood perfusion an important indicator for tissue health and predictor for healing following anastomosis. In this work, we apply a real time multispectral imaging technique to monitor impact on tissue perfusion due to varying interrupted suture spacing and suture tensions. Multispectral tissue images at 470, 540, 560, 580, 670 and 760 nm are analyzed in conjunction with an empirical model based on diffuse reflectance process to quantify the hemoglobin oxygen saturation within the suture site. The investigated tissues for anastomoses include porcine small (jejunum and ileum) and large (transverse colon) intestines. Two experiments using interrupted suturing with suture spacing of 1, 2, and 3 mm and tension levels from 0 N to 2.5 N are conducted. Tissue perfusion at 5, 10, 20 and 30 min after suturing are recorded and compared with the initial normal state. The result indicates the contrast between healthy and ischemic tissue areas and assists the determination of suturing spacing and tension. Therefore, the assessment of tissue perfusion will permit the development and intra-surgical monitoring of an optimal suture protocol during anastomosis with less complications and improved functional outcome.

  20. Effect of methotrexate on perfusion and nitrogen-13 glutamate uptake in the Walker-256 carcinosarcoma

    SciTech Connect

    Knapp, W.H.; Panzer, M.; Helus, F.; Layer, K.; Sinn, H.J.; Ostertag, H.

    1988-02-01

    The tissue uptake of (/sup 13/N)glutamate (glu) was related to that of (/sup 11/C)butanol (but), a highly diffusible perfusion tracer. In 25 rats bearing Walker-256 carcinomas tumor-to-muscle glu uptake averaged 6.34 +/- 2.84 (s.d.) prior to interventions and the respective uptake of but was 6.79 +/- 3.08 (y = 0.03 + 0.94x). One hour after selective intraarterial administration of methotrexate (mtx), glu uptake fell by 47%, whereas blood flow remained within the pretreatment range (N = 9). Four hours after mtx, perfusion was reduced by approximately 40%, and 2 days later both perfusion and glu uptake reached extremely low levels. No significant difference in the effect of 10 and 50 mg/kg mtx was observed. Regional tissue mtx uptake estimations using /sup 77/Br-labeled bromomethotrexate did not reveal any significant uptake in muscle. The relationship between tumor-to-muscle uptake of glu and but (/sup 13/N//sup 11/C-index) was 0.94 +/- 0.015 (s.e.m., N = 25) before intervention. After methotrexate (1 hr, 4 hr, and 2 days) this index was 0.58 +/- 0.06 (N = 9), and 0.85 +/- 0.04 (N = 11) and 1.03 +/- 0.05 (N = 5), respectively. These values demonstrate an early mtx-induced uncoupling of glu uptake with respect to perfusion.

  1. In vitro performance of a perfusion and oxygenation optical sensor using a unique liver phantom

    NASA Astrophysics Data System (ADS)

    Akl, Tony J.; King, Travis J.; Long, Ruiqi; Ericson, M. N.; Wilson, Mark A.; McShane, Michael J.; Coté, Gerard L.

    2012-03-01

    Between the years 1999 and 2008, on average 2,052 people died per year on the waiting list for liver transplants. Monitoring perfusion and oxygenation in transplanted organs in the 7 to 14 days period post-transplant can enhance graft and patient survival rates, and resultantly increase the availability of organs. In this work, we present in vitro results using a unique liver phantom that support the ability of our sensor to detect perfusion changes in the portal vein at low levels (50 mL/min . 4.5% of normal level). Our sensor measures diffuse reflection from three wavelengths (735, 805 and 940 nm) around the hemoglobin isobestic point (805 nm) to determine perfusion and oxygenation separately. To assess the sensitivity of our sensor to flow changes in the low range, we used two peristaltic pumps to pump a dye solution mimicking the optical properties of oxygenated blood, at various rates, through a PDMS based phantom mimicking the optical properties of liver tissue. The collected pulsatile signal increased by 120% (2.2X) for every 100 mL/min flow rise for all three wavelengths in the range 50 to 500 mL/min. In addition, we used different dye mixtures to mimic oxygenation changes at constant perfusion/flow levels. The optical properties of the dye mixtures mimic oxygen saturations ranging between 0 and 100%. The sensor was shown to be sensitive to changes in oxygen saturations above 50%.

  2. Whole-Brain CT Perfusion to Quantify Acute Ischemic Penumbra and Core.

    PubMed

    Lin, Longting; Bivard, Andrew; Krishnamurthy, Venkatesh; Levi, Christopher R; Parsons, Mark W

    2016-06-01

    Purpose To validate the use of perfusion computed tomography (CT) with whole-brain coverage to measure the ischemic penumbra and core and to compare its performance to that of limited-coverage perfusion CT. Materials and Methods Institutional ethics committee approval and informed consent were obtained. Patients (n = 296) who underwent 320-detector CT perfusion within 6 hours of the onset of ischemic stroke were studied. First, the ischemic volume at CT perfusion was compared with the penumbra and core reference values at magnetic resonance (MR) imaging to derive CT perfusion penumbra and core thresholds. Second, the thresholds were tested in a different group of patients to predict the final infarction at diffusion-weighted imaging 24 hours after CT perfusion. Third, the change in ischemic volume delineated by the optimal penumbra and core threshold was determined as the brain coverage was gradually reduced from 160 mm to 20 mm. The Wilcoxon signed-rank test, concordance correlation coefficient (CCC), and analysis of variance were used for the first, second, and third steps, respectively. Results CT perfusion at penumbra and core thresholds resulted in the least volumetric difference from MR imaging reference values with delay times greater than 3 seconds and delay-corrected cerebral blood flow of less than 30% (P = .34 and .33, respectively). When the thresholds were applied to the new group of patients, prediction of the final infarction was allowed with delay times greater than 3 seconds in patients with no recanalization of the occluded artery (CCC, 0.96 [95% confidence interval: 0.92, 0.98]) and with delay-corrected cerebral blood flow less than 30% in patients with complete recanalization (CCC, 0.91 [95% confidence interval: 0.83, 0.95]). However, the ischemic volume with a delay time greater than 3 seconds was underestimated when the brain coverage was reduced to 80 mm (P = .04) and the core volume measured as cerebral blood flow less than 30% was

  3. Cardiac tissue engineering using perfusion bioreactor systems

    PubMed Central

    Radisic, Milica; Marsano, Anna; Maidhof, Robert; Wang, Yadong; Vunjak-Novakovic, Gordana

    2009-01-01

    This protocol describes tissue engineering of synchronously contractile cardiac constructs by culturing cardiac cell populations on porous scaffolds (in some cases with an array of channels) and bioreactors with perfusion of culture medium (in some cases supplemented with an oxygen carrier). The overall approach is ‘biomimetic’ in nature as it tends to provide in vivo-like oxygen supply to cultured cells and thereby overcome inherent limitations of diffusional transport in conventional culture systems. In order to mimic the capillary network, cells are cultured on channeled elastomer scaffolds that are perfused with culture medium that can contain oxygen carriers. The overall protocol takes 2–4 weeks, including assembly of the perfusion systems, preparation of scaffolds, cell seeding and cultivation, and on-line and end-point assessment methods. This model is well suited for a wide range of cardiac tissue engineering applications, including the use of human stem cells, and high-fidelity models for biological research. PMID:18388955

  4. Perfusion in Britain: the early days.

    PubMed

    Braimbridge, Mark V

    2004-07-01

    Experimental perfusion was largely the province of Germany in the nineteenth century but in the mid-twentieth century the focus of perfusion switched to the USA with the explosive clinical advances of Lillehei, Kirklin and Cooley. British clinical perfusion started with Melrose in 1953 at the Postgraduate Medical School in London but, as in other centres at that time, stopped due to the high mortality. The arrival of hands-on experience of American expertise via returning research fellows and other visitors to the USA enabled the first successful on-going series to begin at the Hammersmith Hospital with Cleland in 1957 and then to spread around the country. The various problems of those early 1950s days are described in the units starting then. PMID:15376765

  5. Perfusion and ventilation of isolated canine lungs

    PubMed Central

    Otto, T. J.; Trenkner, M.; Stopczyk, A.; Gawdziński, M.; Chełstowska, B.

    1968-01-01

    In order to evaluate methods of preserving lungs for use in transplantation, experiments on 28 mongrel dogs were carried out. Two methods were tried—first, mechanical respiration of isolated lungs under deep hypothermia, with the vascular bed filled with blood; and, secondly, the perfusion of isolated lungs with the aid of a modified DeWall's apparatus. Allogenic transplantations of lungs preserved in both ways were carried out. Gasometric and histological examinations of preserved lungs, before and after transplantation, were performed. The best results were obtained with perfusion under hypothermic conditions; ventilation without perfusion resulted in failure. Lung transplantation was successful when, after being preserved, the lung remained unchanged. Major discrepancies between the macroscopic and microscopic findings in preserved lungs were observed. An original classification of the changes occurring in preserved lungs is proposed. PMID:4886091

  6. Myocardial perfusion scintigraphy: the evidence.

    PubMed

    Underwood, S R; Anagnostopoulos, C; Cerqueira, M; Ell, P J; Flint, E J; Harbinson, M; Kelion, A D; Al-Mohammad, A; Prvulovich, E M; Shaw, L J; Tweddel, A C

    2004-02-01

    This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by

  7. Biomimetic direction of arrival estimation for resolving front-back confusions in hearing aids

    PubMed Central

    Archer-Boyd, Alan W.; Whitmer, William M.; Brimijoin, W. Owen; Soraghan, John J.

    2015-01-01

    Sound sources at the same angle in front or behind a two-microphone array (e.g., bilateral hearing aids) produce the same time delay and two estimates for the direction of arrival: A front-back confusion. The auditory system can resolve this issue using head movements. To resolve front-back confusion for hearing-aid algorithms, head movement was measured using an inertial sensor. Successive time-delay estimates between the microphones are shifted clockwise and counterclockwise by the head movement between estimates and aggregated in two histograms. The histogram with the largest peak after multiple estimates predicted the correct hemifield for the source, eliminating the front-back confusions. PMID:25994734

  8. Biomimetic direction of arrival estimation for resolving front-back confusions in hearing aids.

    PubMed

    Archer-Boyd, Alan W; Whitmer, William M; Brimijoin, W Owen; Soraghan, John J

    2015-05-01

    Sound sources at the same angle in front or behind a two-microphone array (e.g., bilateral hearing aids) produce the same time delay and two estimates for the direction of arrival: A front-back confusion. The auditory system can resolve this issue using head movements. To resolve front-back confusion for hearing-aid algorithms, head movement was measured using an inertial sensor. Successive time-delay estimates between the microphones are shifted clockwise and counterclockwise by the head movement between estimates and aggregated in two histograms. The histogram with the largest peak after multiple estimates predicted the correct hemifield for the source, eliminating the front-back confusions. PMID:25994734

  9. Characteristics of Patients Who Report Confusion After Reading Their Primary Care Clinic Notes Online.

    PubMed

    Root, Joseph; Oster, Natalia V; Jackson, Sara L; Mejilla, Roanne; Walker, Jan; Elmore, Joann G

    2016-01-01

    Patient access to online electronic medical records (EMRs) is increasing and may offer benefits to patients. However, the inherent complexity of medicine may cause confusion. We elucidate characteristics and health behaviors of patients who report confusion after reading their doctors' notes online. We analyzed data from 4,528 patients in Boston, MA, central Pennsylvania, and Seattle, WA, who were granted online access to their primary care doctors' clinic notes and who viewed at least one note during the 1-year intervention. Three percent of patients reported confusion after reading their visit notes. These patients were more likely to be at least 70 years of age (p < .0001), have fewer years of education (p < .0017), be unemployed (p < .0001), have lower levels of self-reported health (p < .0043), and worry more after reading visit notes (relative risk [RR] 4.83; confidence interval [CI] 3.17, 7.36) compared to patients who were not confused. In adjusted analyses, they were less likely to report feeling more in control of their health (RR 0.42; CI 0.25, 0.71), remembering their care plan (RR 0.26; CI 0.17, 0.42), and understanding their medical conditions (RR 0.32; CI 0.19, 0.54) as a result of reading their doctors' notes compared to patients who were not confused. Patients who were confused by reading their doctors' notes were less likely to report benefits in health behaviors. Understanding this small subset of patients is a critical step in reducing gaps in provider-patient communication and in efforts to tailor educational approaches for patients. PMID:26529325

  10. Indication Alerts Intercept Drug Name Confusion Errors during Computerized Entry of Medication Orders

    PubMed Central

    Galanter, William L.; Bryson, Michelle L.; Falck, Suzanne; Rosenfield, Rachel; Laragh, Marci; Shrestha, Neeha; Schiff, Gordon D.; Lambert, Bruce L.

    2014-01-01

    Background Confusion between similar drug names is a common cause of potentially harmful medication errors. Interventions to prevent these errors at the point of prescribing have had limited success. The purpose of this study is to measure whether indication alerts at the time of computerized physician order entry (CPOE) can intercept drug name confusion errors. Methods and Findings A retrospective observational study of alerts provided to prescribers in a public, tertiary hospital and ambulatory practice with medication orders placed using CPOE. Consecutive patients seen from April 2006 through February 2012 were eligible if a clinician received an indication alert during ordering. A total of 54,499 unique patients were included. The computerized decision support system prompted prescribers to enter indications when certain medications were ordered without a coded indication in the electronic problem list. Alerts required prescribers either to ignore them by clicking OK, to place a problem in the problem list, or to cancel the order. Main outcome was the proportion of indication alerts resulting in the interception of drug name confusion errors. Error interception was determined using an algorithm to identify instances in which an alert triggered, the initial medication order was not completed, and the same prescriber ordered a similar-sounding medication on the same patient within 5 minutes. Similarity was defined using standard text similarity measures. Two clinicians performed chart review of all cases to determine whether the first, non-completed medication order had a documented or non-documented, plausible indication for use. If either reviewer found a plausible indication, the case was not considered an error. We analyzed 127,458 alerts and identified 176 intercepted drug name confusion errors, an interception rate of 0.14±.01%. Conclusions Indication alerts intercepted 1.4 drug name confusion errors per 1000 alerts. Institutions with CPOE should consider

  11. Holographic diffusers

    NASA Astrophysics Data System (ADS)

    Wadle, Stephen; Wuest, Daniel; Cantalupo, John; Lakes, Roderic S.

    1994-01-01

    Holographic diffusers are prepared using silver halide (Agfa 8E75 and Kodak 649F) and photopolymer (Polaroid DMP 128 and DuPont 600, 705, and 150 series) media. It is possible to control the diffusion angle in three ways: by selection of the properties of the source diffuser, by control of its subtended angle, and by selection of the holographic medium. Several conventional diffusers based on refraction or scattering of light are examined for comparison.

  12. Effects of laser acupuncture on blood perfusion rate

    NASA Astrophysics Data System (ADS)

    Wang, Xian-ju; Zeng, Chang-chun; Liu, Han-ping; Liu, Song-hao; Liu, Liang-gang

    2006-09-01

    Based on Pennes equation, the influences of the intensity and the impulse frequency of laser acupuncture on the point tissues' blood flow perfusion rate are discussed. We find that the blood perfusion rate of point tissue increases with the intensity of laser acupuncture increasing. After impulse laser acupuncture the point tissue blood perfusion rate increase little, but after continuum laser acupuncture the point tissues blood perfusion rate increase much.

  13. Object Sizes from Reionization to the Present, and the Natural Confusion Limit Expected in Ultradeep Surveys

    NASA Astrophysics Data System (ADS)

    Windhorst, R.; Cohen, S.; Jansen, R.; Odewahn, S.; Driver, S.; Kawata, D.; Gibson, B.; Gardner, J. P.; Hopkins, A.

    2002-12-01

    We discuss the ph natural confusion limit for the 6m James Webb Space Telescope (JWST; launch planned in 2010), and for the Square Kilometer Array (SKA; becoming reality in a decade). First, we summarize the observed half-light radius vs. flux relation for the galaxy population from the RC3 level to the HDF limit. Together with size estimates from hierarchical models fainter than J(1.35μ )AB~=28 mag and model extrapolations of the faint galaxy counts from JAB~=28 to 34 mag, we estimate the ph natural confusion limit for JWST due to the finite object sizes. A rather unexpected result is that for ultradeep surveys with ~=0.1" FWHM resolution, the ph natural confusion limit may become ph more important in the definition of faint source samples than the traditional surface brightness (SB) limits. This may already be somewhat visible in the deepest HDF images for AB>=25 mag. This does, however, ph not mean that the deepest JWST samples will be fundamentally limited by ph natural confusion. Instead, for JAB>=28--30 mag, faint objects seen by JWST are likely mostly unresolved at 0.08" FWHM. In this case, the deepest JWST images will be limited only by ph instrumental confusion (i.e., by the telescope FWHM), which doesn't set in until around JAB>=33.5 mag. Last, we compute the SKA ph natural confusion limit from the JWST results, assuming that the same population of faint irregular, peculiar and merging/star-forming objects that dominates the faint galaxy counts likely dominates the radio source counts at nanoJansky levels. The SKA will need to have resolutions better than 50--100 m.a.s. (FWHM) to not run into the ph instrumental confusion limit at nanoJy levels. At S1.4~=10 nanoJy, the SKA will likely not run into the ph natural confusion limit, ph if the slope of the nanoJy counts remains below γ <=1.7 ph and if the ratio of radio to optical--near-IR sizes remains close to unity. We acknowledge funding from NASA Grant NAG5-12460.

  14. Subsyllabic structure reflected in letter confusability effects in Korean word recognition.

    PubMed

    Lee, Chang H; Taft, Marcus

    2011-02-01

    Korean subsyllabic structure was investigated by observing the pattern of responses arising from letter transpositions within a syllable in the Hangul script. Experiment 1 revealed no confusions when the onset and coda of one syllable of a disyllabic word were transposed. This was also the case in Experiment 2, where the transposition took place within a syllable having a coda composed of two consonants. However, confusion with the baseword was observed when the two consonants within the complex coda were themselves transposed. These results are taken to support the view that Hangul (and possibly all concatenating orthographic scripts) is processed based on its onset, vowel, and coda structure. PMID:21327354

  15. Diffusion MRI

    NASA Astrophysics Data System (ADS)

    Fukuyama, Hidenao

    Recent advances of magnetic resonance imaging have been described, especially stressed on the diffusion sequences. We have recently applied the diffusion sequence to functional brain imaging, and found the appropriate results. In addition to the neurosciences fields, diffusion weighted images have improved the accuracies of clinical diagnosis depending upon magnetic resonance images in stroke as well as inflammations.

  16. The prognostic value of non-perfusion variables obtained during vasodilator stress myocardial perfusion imaging.

    PubMed

    Bajaj, Navkaranbir S; Singh, Siddharth; Farag, Ayman; El-Hajj, Stephanie; Heo, Jack; Iskandrian, Ami E; Hage, Fadi G

    2016-06-01

    Myocardial perfusion imaging (MPI) is an established diagnostic test that provides useful prognostic data in patients with known or suspected coronary artery disease. In more than half of the patients referred for stress testing, vasodilator stress is used in lieu of exercise. Unlike exercise, vasodilator stress does not provide information on exercise and functional capacity, heart rate recovery, and chronotropy, and ECG changes are less frequent. These non-perfusion data provide important prognostic and patient management information. Further, event rates in patients undergoing vasodilator MPI are higher than in those undergoing exercise MPI and even in those with normal images probably due to higher pretest risk. However, there are a number of non-perfusion variables that are obtained during vasodilator stress testing, which have prognostic relevance but their use has not been well emphasized. The purpose of this review is to summarize the prognostic values of these non-perfusion data obtained during vasodilator MPI. PMID:26940574

  17. Nuclear cardiology: Myocardial perfusion and function

    SciTech Connect

    Seldin, D.W. )

    1991-08-01

    Myocardial perfusion studies continue to be a major focus of research, with new investigations of the relationship of exercise-redistribution thallium imaging to diagnosis, prognosis, and case management. The redistribution phenomenon, which seemed to be fairly well understood a few years ago, is now recognized to be much more complex than originally thought, and various strategies have been proposed to clarify the meaning of persistent defects. Pharmacologic intervention with dipyridamole and adenosine has become available as an alternative to exercise, and comparisons with exercise imaging and catheterization results have been described. Thallium itself is no longer the sole single-photon perfusion radiopharmaceutical; two new technetium agents are now widely available. In addition to perfusion studies, advances in the study of ventricular function have been made, including reports of studies performed in conjunction with technetium perfusion studies, new insights into cardiac physiology, and the prognostic and case-management information that function studies provide. Finally, work has continued with monoclonal antibodies for the identification of areas of myocyte necrosis. 41 references.

  18. Asynchronicity of Facial Blood Perfusion in Migraine

    PubMed Central

    Zaproudina, Nina; Teplov, Victor; Nippolainen, Ervin; Lipponen, Jukka A.; Kamshilin, Alexei A.; Närhi, Matti; Karjalainen, Pasi A.; Giniatullin, Rashid

    2013-01-01

    Asymmetrical changes in blood perfusion and asynchronous blood supply to head tissues likely contribute to migraine pathophysiology. Imaging was widely used in order to understand hemodynamic variations in migraine. However, mapping of blood pulsations in the face of migraineurs has not been performed so far. We used the Blood Pulsation Imaging (BPI) technique, which was recently developed in our group, to establish whether 2D-imaging of blood pulsations parameters can reveal new biomarkers of migraine. BPI characteristics were measured in migraineurs during the attack-free interval and compared to healthy subjects with and without a family history of migraine. We found a novel phenomenon of transverse waves of facial blood perfusion in migraineurs in contrast to healthy subjects who showed synchronous blood delivery to both sides of the face. Moreover, the amplitude of blood pulsations was symmetrically distributed over the face of healthy subjects, but asymmetrically in migraineurs and subjects with a family history of migraine. In the migraine patients we found a remarkable correlation between the side of unilateral headache and the direction of the blood perfusion wave. Our data suggest that migraine is associated with lateralization of blood perfusion and asynchronous blood pulsations in the facial area, which could be due to essential dysfunction of the autonomic vascular control in the face. These findings may further enhance our understanding of migraine pathophysiology and suggest new easily available biomarkers of this pathology. PMID:24324592

  19. Gradient-enhanced FAWSETS perfusion measurements

    NASA Astrophysics Data System (ADS)

    Marro, Kenneth I.; Lee, Donghoon; Hyyti, Outi M.

    2005-08-01

    This work describes the use of custom-built gradients to enhance skeletal muscle perfusion measurements acquired with a previously described arterial spin labeling technique known as FAWSETS (flow-driven arterial water stimulation with elimination of tissue signal). Custom-built gradients provide active control of the static magnetic field gradient on which FAWSETS relies for labeling. This allows selective, 180° modulations of the phase of the perfusion component of the signal. Phase cycling can then be implemented to eliminate all extraneous components leaving a signal that exclusively reflects capillary-level perfusion. Gradient-enhancement substantially reduces acquisition time and eliminates the need to acquire an ischemic signal to quantify perfusion. This removes critical obstacles to application of FAWSETS in organs other than skeletal muscle and makes the measurements more desirable for clinical environments. The basic physical principles of gradient-enhancement are demonstrated in flow phantom experiments and in vivo utility is demonstrated in rat hind limb during stimulated exercise.

  20. Urate synthesis in the perfused chick liver

    PubMed Central

    Barratt, Eileen; Buttery, Peter J.; Boorman, K. Neil

    1974-01-01

    Urate synthesis was studied in a perfused chicken liver preparation. The perfused liver had an ATP/ADP ratio of 0.29±0.05(6) compared with 0.34±0.07(10) in liver obtained from chicks under ether anaesthesia. Lactate/pyruvate ratios were 9.4±1.7(5) in the perfused liver and 14.8±1.8(5) in the rapidly sampled liver. Urate synthesis was only marginally stimulated by glycine, glutamine, aspartic acid or NH4Cl, but significant increases were observed with phosphoribosyl pyrophosphate, aminoimidazolecarboxylic acid riboside, inosine, inosinic acid and xanthine. Urate synthesis from glycine, glutamine, NH4Cl, asparagine, alanine, histidine and a mixture of 21 amino acids was obtained on inclusion of insulin in the perfusion medium. Evidence for the inclusion of the carbon of histidine into uric acid was obtained. Aspects of the energy consumption associated with the conversion of excess of amino acid into uric acid are considered. PMID:4462579

  1. Automated sonographic evaluation of testicular perfusion

    NASA Astrophysics Data System (ADS)

    Thierman, Jonathan S.; Clement, Gregory T.; Kalish, Leslie A.; O'Kane, Patrick L.; Frauscher, Ferdinand; Paltiel, Harriet J.

    2006-07-01

    Contrast-enhanced ultrasound (US) imaging is potentially applicable to the investigation of vascular disorders of the testis. We investigated the ability of two automated computer algorithms to analyse contrast-enhanced pulse inversion US data in a rabbit model of unilateral testicular ischaemia and to correctly determine relative testicular perfusion: nonlinear curve fitting of the US backscatter intensity as a function of time; and spectral analysis of the intensity time trace. We compared (i) five metrics based on the algorithmic data to testicular perfusion ratios obtained with radiolabelled microspheres, a reference standard; (ii) qualitative assessment of the US images by two independent readers blinded to the side of the experimental and control testes to the radiolabelled microsphere perfusion ratios; and (iii) results of the algorithmically-derived metrics to the qualitative assessments of the two readers. For the curve fit method, the algorithmically-derived metrics agreed with the reference standard in 54% to 68% of all cases. For the spectral method, the results agreed in 70% of all cases. The two readers agreed with the reference standard in 40% and 35% of all cases, respectively. These results suggest that automated methods of analysis may provide useful information in the assessment of testicular perfusion.

  2. Simplified prototyping of perfusable polystyrene microfluidics

    PubMed Central

    Tran, Reginald; Ahn, Byungwook; R. Myers, David; Qiu, Yongzhi; Sakurai, Yumiko; Moot, Robert; Mihevc, Emma; Trent Spencer, H.; Doering, Christopher; A. Lam, Wilbur

    2014-01-01

    Cell culture in microfluidic systems has primarily been conducted in devices comprised of polydimethylsiloxane (PDMS) or other elastomers. As polystyrene (PS) is the most characterized and commonly used substrate material for cell culture, microfluidic cell culture would ideally be conducted in PS-based microsystems that also enable tight control of perfusion and hydrodynamic conditions, which are especially important for culture of vascular cell types. Here, we report a simple method to prototype perfusable PS microfluidics for endothelial cell culture under flow that can be fabricated using standard lithography and wet laboratory equipment to enable stable perfusion at shear stresses up to 300 dyn/cm2 and pumping pressures up to 26 kPa for at least 100 h. This technique can also be extended to fabricate perfusable hybrid PS-PDMS microfluidics of which one application is for increased efficiency of viral transduction in non-adherent suspension cells by leveraging the high surface area to volume ratio of microfluidics and adhesion molecules that are optimized for PS substrates. These biologically compatible microfluidic devices can be made more accessible to biological-based laboratories through the outsourcing of lithography to various available microfluidic foundries. PMID:25379106

  3. Comparing Normothermic Machine Perfusion Preservation With Different Perfusates on Porcine Livers From Donors After Circulatory Death.

    PubMed

    Liu, Q; Nassar, A; Farias, K; Buccini, L; Mangino, M J; Baldwin, W; Bennett, A; O'Rourke, C; Iuppa, G; Soliman, B G; Urcuyo-Llanes, D; Okamoto, T; Uso, T D; Fung, J; Abu-Elmagd, K; Miller, C; Quintini, C

    2016-03-01

    The utilization of normothermic machine perfusion (NMP) may be an effective strategy to resuscitate livers from donation after circulatory death (DCD). There is no consensus regarding the efficacy of different perfusates on graft and bile duct viability. The aim of this study was to compare, in an NMP porcine DCD model, the preservation potential of three different perfusates. Twenty porcine livers with 60 min of warm ischemia were separated into four preservation groups: cold storage (CS), NMP with Steen solution (Steen; XVIVO Perfusion Inc., Denver, CO), Steen plus red blood cells (RBCs), or whole blood (WB). All livers were preserved for 10 h and reperfused to simulate transplantation for 24 h. During preservation, the NMP with Steen group presented the highest hepatocellular injury. At reperfusion, the CS group had the lowest bile production and the worst hepatocellular injury compared with all other groups, followed by NMP with Steen; the Steen plus RBC and WB groups presented the best functional and hepatocellular injury outcomes, with WB livers showing lower aspartate aminotransferase release and a trend toward better results for most parameters. Based on our results, a perfusate that contains an oxygen carrier is most effective in a model of NMP porcine DCD livers compared with Steen solution. Specifically, WB-perfused livers showed a trend toward better outcomes compared with Steen plus RBCs. PMID:26663737

  4. Confusion and Slurred Speech in a 34-Year-Old Woman from India

    PubMed Central

    Chugh, Chandril; Wadhwani, N.; Biller, José

    2011-01-01

    A 34-year-old woman from India, presented with episodes of confusion and progressive speech deterioration. She also had a painless neck “lump”, which persisted despite antibiotics. She was diagnosed to have a space occupying lesion in the left parietal lobe, which was subsequently biopsied. PMID:21687701

  5. Delictual Negligence of Educators in Schools: The Confusing Influence of the "in loco parentis" Doctrine

    ERIC Educational Resources Information Center

    Potgieter, Johan

    2004-01-01

    This article points out that the "in loco parentis" maxim is partly to blame for introducing the confusing "reasonable parent" doctrine as the test for delictual negligence of educators in the school context. It is argued that the standard of care exercised by parents over their children is not appropriate to determine the negligence of educators.…

  6. 17 CFR 260.7a-32 - Incorporation by reference rendering document incomplete, unclear, or confusing.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Incorporation by reference rendering document incomplete, unclear, or confusing. 260.7a-32 Section 260.7a-32 Commodity and Securities... OF 1939 Incorporation by Reference § 260.7a-32 Incorporation by reference rendering...

  7. 17 CFR 260.7a-32 - Incorporation by reference rendering document incomplete, unclear, or confusing.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Incorporation by reference rendering document incomplete, unclear, or confusing. 260.7a-32 Section 260.7a-32 Commodity and Securities... OF 1939 Incorporation by Reference § 260.7a-32 Incorporation by reference rendering...

  8. 17 CFR 260.7a-32 - Incorporation by reference rendering document incomplete, unclear, or confusing.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Incorporation by reference rendering document incomplete, unclear, or confusing. 260.7a-32 Section 260.7a-32 Commodity and Securities... OF 1939 Incorporation by Reference § 260.7a-32 Incorporation by reference rendering...

  9. 17 CFR 260.7a-32 - Incorporation by reference rendering document incomplete, unclear, or confusing.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Incorporation by reference rendering document incomplete, unclear, or confusing. 260.7a-32 Section 260.7a-32 Commodity and Securities... OF 1939 Incorporation by Reference § 260.7a-32 Incorporation by reference rendering...

  10. 17 CFR 260.7a-32 - Incorporation by reference rendering document incomplete, unclear, or confusing.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Incorporation by reference rendering document incomplete, unclear, or confusing. 260.7a-32 Section 260.7a-32 Commodity and Securities... OF 1939 Incorporation by Reference § 260.7a-32 Incorporation by reference rendering...

  11. Perception and Confusion of Speech Sounds by Adults with a Cochlear Implant

    ERIC Educational Resources Information Center

    Rodvik, Arne K.

    2008-01-01

    The aim of this pilot study was to identify the most common speech sound confusions of 5 Norwegian cochlear implanted post-lingually deafened adults. We played recorded nonwords, aCa, iCi and bVb, to our informants, asked them to repeat what they heard, recorded their repetitions and transcribed these phonetically. We arranged the collected data…

  12. The Susceptibility of Young Preschoolers to Source Similarity Effects: Confusing Story or Video Events with Reality

    ERIC Educational Resources Information Center

    Thierry, Karen L.; Pipe, Margaret-Ellen

    2009-01-01

    This study examined children's tendency to confuse events that varied in source similarity, which was manipulated using different media of event presentation. In Experiment 1, children in two age groups (3- and 4-year-olds and 5- and 6-year-olds) experienced a live presentation of an event, and another event was either heard from a story (low…

  13. Molecular techniques for detection of confused flour beetle infestations in stored products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tribolium confusum (confused flour beetle) is a stored-product pest which contaminates a wide range of food products, from flour and cereals to spices. The insect reduces food quality and is responsible for large economic losses every year. Although a number of methods for detection of stored-produc...

  14. A Hierarchy of "Confusable" High-Frequency Words in Isolation and Context.

    ERIC Educational Resources Information Center

    Krieger, Veronica K.

    1981-01-01

    The study assessed the degree to which two sets of disabled readers (17 clinic students with a mean CA of 9 years and 13 fourth-grade disabled readers) commonly and identically confuse high frequency sight words in isolation and context. (Author/CL)

  15. Confusion and the Older Adult. Module A-8. Block A. Basic Knowledge of the Aging Process.

    ERIC Educational Resources Information Center

    Harvey, Dexter; Cap, Orest

    This instructional module on confusion and the older adult is one in a block of 10 modules designed to provide the human services worker who works with older adults with basic information regarding the aging process. An introduction provides an overview of the module content. A listing of general objectives follows. Three sections present…

  16. Clearing the Confusion: Response-to-Intervention as a Set of Principles

    ERIC Educational Resources Information Center

    Barnes, Aaron C.; Harlacher, Jason E.

    2008-01-01

    Response-to-Intervention is a new method of service delivery being implemented in schools. However, the lack of emphasis on the flexible nature of Response-to-Intervention and the varying descriptions of its features within the literature may lead to confusion among school professionals. In order to provide more uniformity among the literature, 5…

  17. Confusions and Contradictions in Family Policy Developments: Application of a Model.

    ERIC Educational Resources Information Center

    Zimmerman, Shirley L.

    1982-01-01

    Applies a model of change to an analysis of recent developments in family policy. The model includes such concepts as cultural values, ideology, purposive group action, and structural relations. Clarifies some of the contradictions and confusions of recent political and organizational developments concerning families. (Author/RC)

  18. Compounding Confusion? When Illustrative Practical Work Falls Short of Its Purpose--A Case Study

    ERIC Educational Resources Information Center

    Haigh, Mavis; France, Beverley; Gounder, Roshni

    2012-01-01

    Illustrative practical work is commonly used in chemistry education to enrich students' understandings of chemical phenomena. However, it is possible that such practical work may not serve to foster understanding but rather cause further confusion. This paper reports the struggles experienced by a group of senior (Year 12) secondary chemistry…

  19. It Was the Most Confusing To Read; It Became Easier To Understand.

    ERIC Educational Resources Information Center

    Lambert, Michele

    1999-01-01

    Describes a writing assignment in which students read only the first two paragraphs of Charles Dickens's novel "A Tale of Two Cities" and then, after some brainstorming and prewriting, write a paragraph or two modeled on those, explaining the confusion and turmoil of the present day. Notes how Dickens's expressions become more familiar and his…

  20. Mental Rotation Does Not Account for Sex Differences in Left-Right Confusion

    ERIC Educational Resources Information Center

    Ocklenburg, Sebastian; Hirnstein, Marco; Ohmann, Hanno Andreas; Hausmann, Markus

    2011-01-01

    Several studies have demonstrated that women believe they are more prone to left-right confusion (LRC) than men. However, while some studies report that there is also a sex difference in LRC tasks favouring men, others report that men and women perform equally well. Recently, it was suggested that sex differences only emerge in LRC tasks when they…

  1. Vowel Confusion Patterns in Adults during Initial 4 Years of Implant Use

    ERIC Educational Resources Information Center

    Vaalimaa, Taina T.; Sorri, Martti J.; Laitakari, Jaakko; Sivonen, Ville; Muhli, Arto

    2011-01-01

    This study investigated adult cochlear implant users' (n == 39) vowel recognition and confusions by an open-set syllable test during 4 years of implant use, in a prospective repeated-measures design. Subjects' responses were coded for phoneme errors and estimated by the generalized mixed model. Improvement in overall vowel recognition was highest…

  2. The Treatment of Six Sigma in Introductory Operations Management Textbooks: Clearing Up the Confusion

    ERIC Educational Resources Information Center

    Ravinder, Handanhal; Misra, Ram B.

    2016-01-01

    This paper critically examines the treatment of the statistical basis for Six Sigma and process capability in popular operations management textbooks. It discusses areas of confusion and suggest ways of treating the topic that make sense to instructors as well as students. Even though Six Sigma was introduced almost 30 years ago, misconceptions…

  3. Mirror-Image Confusions: Implications for Representation and Processing of Object Orientation

    ERIC Educational Resources Information Center

    Gregory, Emma; McCloskey, Michael

    2010-01-01

    Perceiving the orientation of objects is important for interacting with the world, yet little is known about the mental representation or processing of object orientation information. The tendency of humans and other species to confuse mirror images provides a potential clue. However, the appropriate characterization of this phenomenon is not…

  4. Confusing Aspects in the Calculation of the Electrostatic Potential of an Infinite Line of Charge

    ERIC Educational Resources Information Center

    Jimenez, J. L.; Campos, I.; Roa-Neri, J. A. E.

    2012-01-01

    In this work we discuss the trick of eliminating infinite potential of reference arguing that it corresponds to a constant of integration, in the problem of determining the electrostatic potential of an infinite line of charge with uniform density, and show how the problem must be tackled properly. The usual procedure is confusing for most…

  5. Straw Men and False Dichotomies: Overcoming Philosophical Confusion in Chemical Education

    ERIC Educational Resources Information Center

    Taber, Keith S.

    2010-01-01

    Constructivism has been widely considered the most influential perspective in science education research for some decades, and has been the basis of widespread pedagogic advice in many educational contexts. Yet it has been claimed in this "Journal" that the philosophical basis of constructivist thought in chemical education is confused, and…

  6. Energy and the Confused Student IV: A Global Approach to Energy

    ERIC Educational Resources Information Center

    Jewett, John W., Jr.

    2008-01-01

    Energy is a critical concept in physics problem-solving, but is often a major source of confusion for students if the presentation is not carefully crafted by the instructor or the textbook. In the first three articles in this series we discussed several issues related to the teaching of energy concepts. We have saved a major single issue for this…

  7. Is the Word-Superiority Effect in Target Search Tasks Based on Perceptual Confusions?

    ERIC Educational Resources Information Center

    Chastain, Garvin; And Others

    It has been hypothesized that letters in orthographic strings (those that follow the rules of English) are more accurately identified than letters in nonorthographic strings because confusions about the positions of letters are more likely in nonorthographic strings. This hypothesis was tested by giving 16 college students a set of targets, one of…

  8. Attempting To Understand the Class Size and Pupil-Teacher Ratio (PTR) Confusion: A Pilot Study.

    ERIC Educational Resources Information Center

    Achilles, C. M.; Sharp, Mark; Nye, B. A.

    Confusion over the concepts of class size and pupil-teacher ratio (PTR) creates a conundrum for researchers, policy makers, and practitioners. An examination of how these two concepts are different is presented in this paper. A review of the literature suggests that class-size reduction makes a positive overall difference in student achievement,…

  9. Psychometric properties of the Flemish translation of the NEECHAM Confusion Scale

    PubMed Central

    Milisen, Koen; Foreman, Marquis D; Hendrickx, Annik; Godderis, Jan; Abraham, Ivo L; Broos, Paul LO; De Geest, Sabina

    2005-01-01

    Background Determination of a patient's cognitive status by use of a valid and reliable screening instrument is of major importance as early recognition and accurate diagnosis of delirium is necessary for effective management. This study determined the reliability, validity and diagnostic value of the Flemish translation of the NEECHAM Confusion Scale. Methods A sample of 54 elderly hip fracture patients with a mean age of 80.9 years (SD = 7.85) were included. To test the psychometric properties of the NEECHAM Confusion Scale, performance on the NEECHAM was compared to the Confusion Assessment Method (CAM) and the Mini-Mental State Examination (MMSE), by using aggregated data based on 5 data collection measurement points (repeated measures). The CAM and MMSE served as gold standards. Results The alpha coefficient for the total NEECHAM score was high (0.88). Principal components analysis yielded a two-component solution accounting for 70.8% of the total variance. High correlations were found between the total NEECHAM scores and total MMSE (0.75) and total CAM severity scores (-0.73), respectively. Diagnostic values using the CAM algorithm as gold standard showed 76.9% sensitivity, 64.6% specificity, 13.5% positive and 97.5% negative predictive values, respectively. Conclusion This validation of the Flemish version of the NEECHAM Confusion Scale adds to previous evidence suggesting that this scale holds promise as a valuable screening instrument for delirium in clinical practice. Further validation studies in diverse clinical populations; however, are needed. PMID:15792498

  10. Factors in myocardial "perfusion" imaging with ultrafast MRI and Gd-DTPA administration.

    PubMed

    Burstein, D; Taratuta, E; Manning, W J

    1991-08-01

    Ultrafast magnetic resonance imaging (MRI) and first pass observation of an interstitial contrast agent are currently being used to study myocardial perfusion. Image intensity, however, is a function of several parameters, including the delivery of the contrast agent to the interstitium (coronary flow rate and diffusion into the interstitium) and the relaxation properties of the tissue (contrast agent concentration, proton exchange rates, and relative intra- and extracellular volume fractions). In this study, image intensity during gadopentetate dimeglumine (Gd-DTPA) administration with T1-weighted ultrafast MR imaging was assessed in an isolated heart preparation. With increasing Gd-DTPA concentration, the steady-state myocardial image intensity increased but the time to reach steady state remained unchanged, resulting in an increased slope of image intensity change. A range of physiologic perfusion pressures (and resulting coronary flow rates) had insignificant effects on kinetics of Gd-DTPA wash-in or steady-state image intensity, suggesting that diffusion of Gd-DTPA into the interstitium is the rate limiting step in image intensity change with this preparation. Following global ischemia and reperfusion, transmural differences in the slope of image intensity change were apparent. However, the altered steady-state image intensity (due to postischemic edema) makes interpretation of this finding difficult. The studies described here demonstrate that although Gd-DTPA administration combined with ultrafast imaging may be a sensitive indicator of perfusion abnormalities, factors other than perfusion will affect image intensity. Extensive studies will be required before image intensity with this protocol is fully understood. PMID:1775055