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Sample records for observations comparing mdct

  1. Spectrum of Abdominal Aortic Disease in a Tertiary Health Care Setup: MDCT Based Observational Study

    PubMed Central

    Kumar, DG Santosh; Gadabanahalli, Karthik; Kalyanpur, Arjun

    2016-01-01

    considered for surgical treatment. Ten patients with dissection underwent endovascular procedure. Rest of the patients was managed conservatively. Conclusion Aortic disease was observed in 43% of investigated patients. Atherosclerosis with and without aortic aneurysm constituted the largest group. MDCT provided comprehensive information about the lesion and associated complications. In view of the wider availability and desired imaging qualities, MDCT provided optimal information for diagnosis and management of aortic pathology. Majority of our patients (90%) were treated conservatively. PMID:28050476

  2. Accuracy of Monte Carlo simulations compared to in-vivo MDCT dosimetry

    SciTech Connect

    Bostani, Maryam McMillan, Kyle; Cagnon, Chris H.; McNitt-Gray, Michael F.; Mueller, Jonathon W.; Cody, Dianna D.; DeMarco, John J.

    2015-02-15

    Purpose: The purpose of this study was to assess the accuracy of a Monte Carlo simulation-based method for estimating radiation dose from multidetector computed tomography (MDCT) by comparing simulated doses in ten patients to in-vivo dose measurements. Methods: MD Anderson Cancer Center Institutional Review Board approved the acquisition of in-vivo rectal dose measurements in a pilot study of ten patients undergoing virtual colonoscopy. The dose measurements were obtained by affixing TLD capsules to the inner lumen of rectal catheters. Voxelized patient models were generated from the MDCT images of the ten patients, and the dose to the TLD for all exposures was estimated using Monte Carlo based simulations. The Monte Carlo simulation results were compared to the in-vivo dose measurements to determine accuracy. Results: The calculated mean percent difference between TLD measurements and Monte Carlo simulations was −4.9% with standard deviation of 8.7% and a range of −22.7% to 5.7%. Conclusions: The results of this study demonstrate very good agreement between simulated and measured doses in-vivo. Taken together with previous validation efforts, this work demonstrates that the Monte Carlo simulation methods can provide accurate estimates of radiation dose in patients undergoing CT examinations.

  3. Hepatic Arterial Configuration in Relation to the Segmental Anatomy of the Liver; Observations on MDCT and DSA Relevant to Radioembolization Treatment

    SciTech Connect

    Hoven, Andor F. van den Leeuwen, Maarten S. van Lam, Marnix G. E. H. Bosch, Maurice A. A. J. van den

    2015-02-15

    PurposeCurrent anatomical classifications do not include all variants relevant for radioembolization (RE). The purpose of this study was to assess the individual hepatic arterial configuration and segmental vascularization pattern and to develop an individualized RE treatment strategy based on an extended classification.MethodsThe hepatic vascular anatomy was assessed on MDCT and DSA in patients who received a workup for RE between February 2009 and November 2012. Reconstructed MDCT studies were assessed to determine the hepatic arterial configuration (origin of every hepatic arterial branch, branching pattern and anatomical course) and the hepatic segmental vascularization territory of all branches. Aberrant hepatic arteries were defined as hepatic arterial branches that did not originate from the celiac axis/CHA/PHA. Early branching patterns were defined as hepatic arterial branches originating from the celiac axis/CHA.ResultsThe hepatic arterial configuration and segmental vascularization pattern could be assessed in 110 of 133 patients. In 59 patients (54 %), no aberrant hepatic arteries or early branching was observed. Fourteen patients without aberrant hepatic arteries (13 %) had an early branching pattern. In the 37 patients (34 %) with aberrant hepatic arteries, five also had an early branching pattern. Sixteen different hepatic arterial segmental vascularization patterns were identified and described, differing by the presence of aberrant hepatic arteries, their respective vascular territory, and origin of the artery vascularizing segment four.ConclusionsThe hepatic arterial configuration and segmental vascularization pattern show marked individual variability beyond well-known classifications of anatomical variants. We developed an individualized RE treatment strategy based on an extended anatomical classification.

  4. Simultaneous screening for osteoporosis at CT colonography: bone mineral density assessment using MDCT attenuation techniques compared with the DXA reference standard.

    PubMed

    Pickhardt, Perry J; Lee, Lawrence J; del Rio, Alejandro Muñoz; Lauder, Travis; Bruce, Richard J; Summers, Ron M; Pooler, B Dustin; Binkley, Neil

    2011-09-01

    The purpose of this study was to evaluate the utility of lumbar spine attenuation measurement for bone mineral density (BMD) assessment at screening computed tomographic colonography (CTC) using central dual-energy X-ray absorptiometry (DXA) as the reference standard. Two-hundred and fifty-two adults (240 women and 12 men; mean age 58.9 years) underwent CTC screening and central DXA BMD measurement within 2 months (mean interval 25.0 days). The lowest DXA T-score between the spine and hip served as the reference standard, with low BMD defined per World Health Organization as osteoporosis (DXA T-score ≤ -2.5) or osteopenia (DXA T-score between -1.0 and -2.4). Both phantomless quantitative computed tomography (QCT) and simple nonangled region-of-interest (ROI) multi-detector CT (MDCT) attenuation measurements were applied to the T(12) -L(5) levels. The ability to predict osteoporosis and low BMD (osteoporosis or osteopenia) by DXA was assessed. A BMD cut-off of 90 mg/mL at phantomless QCT yielded 100% sensitivity for osteoporosis (29 of 29) and a specificity of 63.8% (143 of 224); 87.2% (96 of 110) below this threshold had low BMD and 49.6% (69 of 139) above this threshold had normal BMD at DXA. At L(1) , a trabecular ROI attenuation cut-off of 160 HU was 100% sensitive for osteoporosis (29 of 29), with a specificity of 46.4% (104 of 224); 83.9% (125 of 149) below this threshold had low BMD and 57.5% (59/103) above had normal BMD at DXA. ROI performance was similar at all individual T(12) -L(5) levels. At ROC analysis, AUC for osteoporosis was 0.888 for phantomless QCT [95% confidence interval (CI) 0.780-0.946] and ranged from 0.825 to 0.853 using trabecular ROIs at single lumbar levels (0.864; 95% CI 0.752-0.930 at multivariate analysis). Supine-prone reproducibility was better with the simple ROI method compared with QCT. It is concluded that both phantomless QCT and simple ROI attenuation measurements of the lumbar spine are effective for BMD screening at CTC

  5. Evaluating the effect of two different anesthetic protocols on 64-MDCT coronary angiography in dogs

    PubMed Central

    Drees, Randi; Johnson, Rebecca A; Pinkerton, Marie; Del Rio, Alejandro Munoz; Saunders, Jimmy H; François, Christopher J

    2014-01-01

    Heart rate is a major factor influencing diagnostic image quality in computed tomographic coronary artery angiography (MDCT-CA) with an ideal heart rate of 60–65 beats/minute in humans. Using standardized contrast bolus volume, two different clinically applicable anesthetic protocols were compared for effect on cardiovascular parameters and 64-MDCT-CA quality in ten healthy dogs. The protocol using midazolam/fentanyl (A) was hypothesized to result in adequate reduction of heart rate achieving adequate image quality for MDCT-CA studies and having low impact on blood pressure, where as the protocol utilizing dexmedetomidine (B) was expected to result in reduction of heart rate to the target heart range resulting in excellent image quality while possibly showing undesirable effect on the blood pressure values measured. Heart rate was 80.6 ± 7.5bpm with protocol A and 79.2 ± 14.2bpm with protocol B during image acquisition (P=1). R-R intervals allowing for the best depiction of the individual coronary artery segments were found in the end diastolic period and varied between the 70–95% interval. Diagnostic quality was rated excellent, good and moderate in the majority of the segments evaluated, with higher scores given for more proximal segments and lower for more distal segments respectively. Blur was the most commonly observed artifact and most affected the distal segments. There was no significant difference for the optimal reconstruction interval, diagnostic quality and measured length individual segments or proximal diameter of the coronary arteries between both protocols (P=1). Both anesthetic protocols and the standardized bolus volume allow for diagnostic quality coronary 64-MDCT-CA exams. PMID:25065815

  6. Multidetector computed tomography (MDCT) evaluation of myocardial viability: intraindividual comparison of monomeric vs. dimeric contrast media in a rabbit model.

    PubMed

    Mahnken, Andreas H; Jost, Gregor; Bruners, Philipp; Sieber, Martin; Seidensticker, Peter R; Günther, Rolf W; Pietsch, Hubertus

    2009-02-01

    To evaluate the influence of different types of iodinated contrast media on the assessment of myocardial viability, acute myocardial infarction (MI) was surgically induced in six rabbits. Over a period of 45 min, contrast-enhanced cardiac MDCT (64 x 0.6 mm, 80 kV, 680 mAs(eff.)) was repeatedly performed using a contrast medium dose of 600 mg iodine/kg body weight. Animals received randomized iopromide 300 and iodixanol 320, respectively. Attenuation values of healthy and infarcted myocardium were measured. The size of MI was computed and compared with nitroblue tetrazolium (NBT)-stained specimen. The highest attenuation differences between infarcted and healthy myocardium occurred during the arterial phase with 140.0+/-3.5 HU and 141.0+/-2.2 HU for iopromide and iodixanol, respectively. For iodixanol the highest attenuation difference on delayed contrast-enhanced images was achieved 3 min post injection (73.5 HU). A slightly higher attenuation difference was observed for iopromide 6 min after contrast medium injection (82.2 HU), although not statistically significant (p=0.6437). Mean infarct volume as measured by NBT staining was 33.5%+/-13.6%. There was an excellent agreement of infarct sizes among NBT-, iopromide- and iodixanol-enhanced MDCT with concordance-correlation coefficients ranging from rho(c)=0.9928-0.9982. Iopromide and iodixanol both allow a reliable assessment of MI with delayed contrast-enhanced MDCT.

  7. Radiation dose measurement for various parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Lae; Kim, Hee-Joung; Jeon, Seong Su; Cho, Hyo-Min; Nam, So Ra; Jung, Ji-Young

    2008-03-01

    The MDCT parameters affecting radiation dose include tube voltage, tube current, change of beam collimation, and size of the human body. The purpose of this study was to measure and evaluate radiation dose for MDCT parameters. A comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber was performed. The ionization chamber was used for measuring radiation dose in the MDCT, as well as of CTDI W according to temperature and pressure correction factors in the CT room. As a result, the patient dose of CTDI W values linearly increased as tube voltage and current were increased, and nonlinearly decreased as beam collimation was increased. And the CTDI W value which was reflected calibration factors, as well as correction factors of temperature and pressure, was found to be greater by the range of 0.479 ~ 3.162 mGy in effective radiation dose than the uncorrected value. Also, Under the abdomen routine CT conditions used in hospitals, patient exposure dose showed a difference of a maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the application of temperature and pressure of the CT room are crucial in measuring and calculating patient exposure dose.

  8. Effect of Low-Dose MDCT and Iterative Reconstruction on Trabecular Bone Microstructure Assessment

    PubMed Central

    Baum, Thomas; Nasirudin, Radin A.; Mei, Kai; Garcia, Eduardo G.; Burgkart, Rainer; Rummeny, Ernst J.; Kirschke, Jan S.; Noël, Peter B.

    2016-01-01

    We investigated the effects of low-dose multi detector computed tomography (MDCT) in combination with statistical iterative reconstruction algorithms on trabecular bone microstructure parameters. Twelve donated vertebrae were scanned with the routine radiation exposure used in our department (standard-dose) and a low-dose protocol. Reconstructions were performed with filtered backprojection (FBP) and maximum-likelihood based statistical iterative reconstruction (SIR). Trabecular bone microstructure parameters were assessed and statistically compared for each reconstruction. Moreover, fracture loads of the vertebrae were biomechanically determined and correlated to the assessed microstructure parameters. Trabecular bone microstructure parameters based on low-dose MDCT and SIR significantly correlated with vertebral bone strength. There was no significant difference between microstructure parameters calculated on low-dose SIR and standard-dose FBP images. However, the results revealed a strong dependency on the regularization strength applied during SIR. It was observed that stronger regularization might corrupt the microstructure analysis, because the trabecular structure is a very small detail that might get lost during the regularization process. As a consequence, the introduction of SIR for trabecular bone microstructure analysis requires a specific optimization of the regularization parameters. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods. PMID:27447827

  9. Quantitative analysis of the central-chest lymph nodes based on 3D MDCT image data

    NASA Astrophysics Data System (ADS)

    Lu, Kongkuo; Bascom, Rebecca; Mahraj, Rickhesvar P. M.; Higgins, William E.

    2009-02-01

    Lung cancer is the leading cause of cancer death in the United States. In lung-cancer staging, central-chest lymph nodes and associated nodal stations, as observed in three-dimensional (3D) multidetector CT (MDCT) scans, play a vital role. However, little work has been done in relation to lymph nodes, based on MDCT data, due to the complicated phenomena that give rise to them. Using our custom computer-based system for 3D MDCT-based pulmonary lymph-node analysis, we conduct a detailed study of lymph nodes as depicted in 3D MDCT scans. In this work, the Mountain lymph-node stations are automatically defined by the system. These defined stations, in conjunction with our system's image processing and visualization tools, facilitate lymph-node detection, classification, and segmentation. An expert pulmonologist, chest radiologist, and trained technician verified the accuracy of the automatically defined stations and indicated observable lymph nodes. Next, using semi-automatic tools in our system, we defined all indicated nodes. Finally, we performed a global quantitative analysis of the characteristics of the observed nodes and stations. This study drew upon a database of 32 human MDCT chest scans. 320 Mountain-based stations (10 per scan) and 852 pulmonary lymph nodes were defined overall from this database. Based on the numerical results, over 90% of the automatically defined stations were deemed accurate. This paper also presents a detailed summary of central-chest lymph-node characteristics for the first time.

  10. Segmentation of the central-chest lymph nodes in 3D MDCT images.

    PubMed

    Lu, Kongkuo; Higgins, William E

    2011-09-01

    Central-chest lymph nodes play a vital role in lung-cancer staging. The definition of lymph nodes from three-dimensional (3D) multidetector computed-tomography (MDCT) images, however, remains an open problem. We propose two methods for computer-based segmentation of the central-chest lymph nodes from a 3D MDCT scan: the single-section live wire and the single-click live wire. For the single-section live wire, the user first applies the standard live wire to a single two-dimensional (2D) section after which automated analysis completes the segmentation process. The single-click live wire is similar but is almost completely automatic. Ground-truth studies involving human 3D MDCT scans demonstrate the robustness, efficiency, and intra-observer and inter-observer reproducibility of the methods.

  11. Postmortem imaging: MDCT features of postmortem change and decomposition.

    PubMed

    Levy, Angela D; Harcke, Howard Theodore; Mallak, Craig T

    2010-03-01

    Multidetector computed tomography (MDCT) has emerged as an effective imaging technique to augment forensic autopsy. Postmortem change and decomposition are always present at autopsy and on postmortem MDCT because they begin to occur immediately upon death. Consequently, postmortem change and decomposition on postmortem MDCT should be recognized and not mistaken for a pathologic process or injury. Livor mortis increases the attenuation of vasculature and dependent tissues on MDCT. It may also produce a hematocrit effect with fluid levels in the large caliber blood vessels and cardiac chambers from dependent layering erythrocytes. Rigor mortis and algor mortis have no specific MDCT features. In contrast, decomposition through autolysis, putrefaction, and insect and animal predation produce dramatic alterations in the appearance of the body on MDCT. Autolysis alters the attenuation of organs. The most dramatic autolytic changes on MDCT are seen in the brain where cerebral sulci and ventricles are effaced and gray-white matter differentiation is lost almost immediately after death. Putrefaction produces a pattern of gas that begins with intravascular gas and proceeds to gaseous distension of all anatomic spaces, organs, and soft tissues. Knowledge of the spectrum of postmortem change and decomposition is an important component of postmortem MDCT interpretation.

  12. Comparing Two Approaches for Assessing Observation Impact

    NASA Technical Reports Server (NTRS)

    Todling, Ricardo

    2013-01-01

    Langland and Baker introduced an approach to assess the impact of observations on the forecasts. In that approach, a state-space aspect of the forecast is defined and a procedure is derived ultimately relating changes in the aspect with changes in the observing system. Some features of the state-space approach are to be noted: the typical choice of forecast aspect is rather subjective and leads to incomplete assessment of the observing system, it requires availability of a verification state that is in practice correlated with the forecast, and it involves the adjoint operator of the entire data assimilation system and is thus constrained by the validity of this operator. This article revisits the topic of observation impacts from the perspective of estimation theory. An observation-space metric is used to allow inferring observation impact on the forecasts without the limitations just mentioned. Using differences of observation-minus-forecast residuals obtained from consecutive forecasts leads to the following advantages: (i) it suggests a rather natural choice of forecast aspect that directly links to the data assimilation procedure, (ii) it avoids introducing undesirable correlations in the forecast aspect since verification is done against the observations, and (iii) it does not involve linearization and use of adjoints. The observation-space approach has the additional advantage of being nearly cost free and very simple to implement. In its simplest form it reduces to evaluating the statistics of observationminus- background and observation-minus-analysis residuals with traditional methods. Illustrations comparing the approaches are given using the NASA Goddard Earth Observing System.

  13. MDCT Versus MRI Assessment of Tumor Response After Transarterial Chemoembolization for the Treatment of Hepatocellular Carcinoma

    SciTech Connect

    Kloeckner, Roman; Otto, Gerd; Biesterfeld, Stefan; Oberholzer, Katja; Dueber, Christoph; Pitton, Michael B.

    2010-06-15

    The purpose of this study was to compare the ability of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) to evaluate treatment results after transarterial chemoembolization (TACE), with a special focus on the influence of Lipiodol on calculation of tumor necrosis according to EASL criteria. A total of 115 nodules in 20 patients (17 males, 3 females; 69.5 {+-} 9.35 years) with biopsy-proven hepatocellular carcinoma were treated with TACE. Embolization was performed using a doxorubicin-Lipiodol emulsion (group I) or DC Beads loaded with doxorubicin (group II). Follow-up included triphasic contrast-enhanced 64-row MDCT (collimation, 0.625 mm; slice, 3 mm; contrast bolus, 120 ml iomeprol; delay by bolus trigger) and contrast-enhanced MRI (T1 native, T2 native; five dynamic contrast-enhanced phases; 0.1 mmol/kg body weight gadolinium-DTPA; slice thickness, 4 mm). Residual tumor and the extent of tumor necrosis were evaluated according to EASL. Contrast enhancement within tumor lesions was suspected to represent vital tumor. In the Lipiodol-based TACE protocol, MDCT underestimated residual viable tumor compared to MRI, due to Lipiodol artifacts (23.2% vs 47.7% after first, 11.9% vs 31.2% after second, and 11.4% vs 23.7% after third TACE; p = 0.0014, p < 0.001, and p < 0.001, respectively). In contrast to MDCT, MRI was completely free of any artifacts caused by Lipiodol. In the DC Bead-based Lipiodol-free TACE protocol, MRI and CT showed similar residual tumor and rating of treatment results (46.4% vs 41.2%, 31.9 vs 26.8%, and 26.0% vs 25.6%; n.s.). In conclusion, MRI is superior to MDCT for detection of viable tumor residuals after Lipiodol-based TACE. Since viable tumor tissue is superimposed by Lipiodol artifacts in MDCT, MRI is mandatory for reliable decision-making during follow-up after Lipiodol-based TACE protocols.

  14. Spontaneous Renal Artery Dissection as a Cause of Acute Renal Infarction: Clinical and MDCT Findings.

    PubMed

    Yoon, Kibo; Song, Soon Young; Lee, Chang Hwa; Ko, Byung Hee; Lee, Seunghun; Kang, Bo Kyeong; Kim, Mi Mi

    2017-04-01

    The purpose of this study was to assess the incidence of spontaneous renal artery dissection (SRAD) as a cause of acute renal infarction, and to evaluate the clinical and multidetector computed tomography (MDCT) findings of SRAD. From November 2011 to January 2014, 35 patients who were diagnosed with acute renal infarction by MDCT were included. We analyzed the 35 MDCT data sets and medical records retrospectively, and compared clinical and imaging features of SRAD with an embolism, using Fisher's exact test and the Mann-Whitney test. The most common cause of acute renal infarction was an embolism, and SRAD was the second most common cause. SRAD patients had new-onset hypertension more frequently than embolic patients. Embolic patients were found to have increased C-reactive protein (CRP) more often than SRAD patients. Laboratory results, including tests for lactate dehydrogenase (LDH) and blood urea nitrogen (BUN), and the BUN/creatinine ratio (BCR) were significantly higher in embolic patients than SRAD patients. Bilateral renal involvement was detected in embolic patients more often than in SRAD patients. MDCT images of SRAD patients showed the stenosis of the true lumen, due to compression by a thrombosed false lumen. None of SRAD patients progressed to an estimated glomerular filtration rate < 60 mL/min/1.73 m² or to end-stage renal disease during the follow-up period. SRAD is not a rare cause of acute renal infarction, and it has a benign clinical course. It should be considered in a differential diagnosis of acute renal infarction, particularly in patients with new-onset hypertension, unilateral renal involvement, and normal ranges of CRP, LDH, BUN, and BCR.

  15. Spontaneous Renal Artery Dissection as a Cause of Acute Renal Infarction: Clinical and MDCT Findings

    PubMed Central

    2017-01-01

    The purpose of this study was to assess the incidence of spontaneous renal artery dissection (SRAD) as a cause of acute renal infarction, and to evaluate the clinical and multidetector computed tomography (MDCT) findings of SRAD. From November 2011 to January 2014, 35 patients who were diagnosed with acute renal infarction by MDCT were included. We analyzed the 35 MDCT data sets and medical records retrospectively, and compared clinical and imaging features of SRAD with an embolism, using Fisher's exact test and the Mann-Whitney test. The most common cause of acute renal infarction was an embolism, and SRAD was the second most common cause. SRAD patients had new-onset hypertension more frequently than embolic patients. Embolic patients were found to have increased C-reactive protein (CRP) more often than SRAD patients. Laboratory results, including tests for lactate dehydrogenase (LDH) and blood urea nitrogen (BUN), and the BUN/creatinine ratio (BCR) were significantly higher in embolic patients than SRAD patients. Bilateral renal involvement was detected in embolic patients more often than in SRAD patients. MDCT images of SRAD patients showed the stenosis of the true lumen, due to compression by a thrombosed false lumen. None of SRAD patients progressed to an estimated glomerular filtration rate < 60 mL/min/1.73 m2 or to end-stage renal disease during the follow-up period. SRAD is not a rare cause of acute renal infarction, and it has a benign clinical course. It should be considered in a differential diagnosis of acute renal infarction, particularly in patients with new-onset hypertension, unilateral renal involvement, and normal ranges of CRP, LDH, BUN, and BCR. PMID:28244286

  16. Managing patient dose in multi-detector computed tomography(MDCT). ICRP Publication 102.

    PubMed

    Valentin, J

    2007-01-01

    Computed tomography (CT) technology has changed considerably in recent years with the introduction of increasing numbers of multiple detector arrays. There are several parameters specific to multi-detector computed tomography (MDCT) scanners that increase or decrease patient dose systematically compared to older single detector computed tomography (SDCT) scanners. This document briefly reviews the MDCT technology, radiation dose in MDCT, including differences from SDCT and factors that affect dose, radiation risks, and the responsibilities for patient dose management. The document recommends that users need to understand the relationship between patient dose and image quality and be aware that image quality in CT is often higher than that necessary for diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator from selection of scan parameters, and awareness of individual systems is important. Scanning protocols cannot simply be transferred between scanners from different manufacturers and should be determined for each MDCT. If the image quality is appropriately specified by the user, and suited to the clinical task, there will be a reduction in patient dose for most patients. Understanding of some parameters is not intuitive and the selection of image quality parameter values in AEC systems is not straightforward. Examples of some clinical situation shave been included to demonstrate dose management, e.g. CT examinations of the chest, the heart for coronary calcium quantification and non-invasive coronary angiography, colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided interventions. CT is increasingly being used to replace conventional x-ray studies and it is important that patient dose is given careful consideration, particularly with repeated or multiple examinations.

  17. Quantification of arterial plaque and lumen density with MDCT

    SciTech Connect

    Paul, Narinder S.; Blobel, Joerg; Kashani, Hany; Rice, Murray; Ursani, Ali

    2010-08-15

    Purpose: This study aimed to derive a mathematical correction function in order to normalize the CT number measurements for small volume arterial plaque and small vessel mimicking objects, imaged with multidetector CT (MDCT). Methods: A commercially available calcium plaque phantom (QRM GmbH, Moehrendorf, Germany) and a custom built cardiovascular phantom were scanned with 320 and 64 MDCT scanners. The calcium hydroxyapatite plaque phantom contained objects 0.5-5.0 mm in diameter with known CT attenuation nominal values ranging 50-800 HU. The cardiovascular phantom contained vessel mimicking objects 1.0-5.0 mm in diameter with different contrast media. Both phantoms were scanned using clinical protocols for CT angiography and images were reconstructed with different filter kernels. The measured CT number (HU) and diameter of each object were analyzed on three clinical postprocessing workstations. From the resultant data, a mathematical formula was derived based on absorption function exp(-{mu}{sup *}d) to demonstrate the relation between measured CT numbers and object diameters. Results: The percentage reduction in measured CT number (HU) for the group of selected filter kernels, apparent during CT angiography, is dependent only on the object size (plaque or vessel diameter). The derived formula of the form 1-c{sup *}exp(-a{sup *}d{sup b}) showed reduction in CT number for objects between 0.5 and 5 mm in diameter, with asymptote reaching background noise for small objects with diameters nearing the CT in-plane resolution (0.35 mm). No reduction was observed for the objects with diameters equal or larger than 5 mm. Conclusions: A clear mathematical relationship exists between object diameter and reduction in measured CT number in HU. This function is independent of exposure parameters and inherent attenuation properties of the objects studied. Future developments include the incorporation of this mathematical model function into quantification software in order to

  18. MDCT evaluation of potential living renal donor, prior to laparoscopic donor nephrectomy: What the transplant surgeon wants to know?

    PubMed

    Ghonge, Nitin P; Gadanayak, Satyabrat; Rajakumari, Vijaya

    2014-10-01

    As Laparoscopic Donor Nephrectomy (LDN) offers several advantages for the donor such as lesser post-operative pain, fewer cosmetic concerns and faster recovery time, there is growing global trend towards LDN as compared to open nephrectomy. Comprehensive pre-LDN donor evaluation includes assessment of renal morphology including pelvi-calyceal and vascular system. Apart from donor selection, evaluation of the regional anatomy allows precise surgical planning. Due to limited visualization during laparoscopic renal harvesting, detailed pre-transplant evaluation of regional anatomy, including the renal venous anatomy is of utmost importance. MDCT is the modality of choice for pre-LDN evaluation of potential renal donors. Apart from appropriate scan protocol and post-processing methods, detailed understanding of surgical techniques is essential for the Radiologist for accurate image interpretation during pre-LDN MDCT evaluation of potential renal donors. This review article describes MDCT evaluation of potential living renal donor, prior to LDN with emphasis on scan protocol, post-processing methods and image interpretation. The article laid special emphasis on surgical perspectives of pre-LDN MDCT evaluation and addresses important points which transplant surgeons want to know.

  19. Roles of Naturalistic Observation in Comparative Psychology

    ERIC Educational Resources Information Center

    Miller, David B.

    1977-01-01

    "Five roles are considered by which systematic, quantified field research can augment controlled laboratory experimentation in terms of increasing the validity of laboratory studies." Advocates that comparative psychologists should "take more initiative in designing, executing, and interpreting our experiments with regard to the natural history of…

  20. Comparative Effectiveness Research Using Observational Data: Active Comparators to Emulate Target Trials with Inactive Comparators

    PubMed Central

    Huitfeldt, Anders; Hernan, Miguel A.; Kalager, Mette; Robins, James M.

    2016-01-01

    Introduction: Because a comparison of noninitiators and initiators of treatment may be hopelessly confounded, guidelines for the conduct of observational research often recommend using an “active” comparator group consisting of people who initiate a treatment other than the medication of interest. In this paper, we discuss the conditions under which this approach is valid if the goal is to emulate a trial with an inactive comparator. Identification of Effects: We provide conditions under which a target trial in a subpopulation can be validly emulated from observational data, using an active comparator that is known or believed to be inactive for the outcome of interest. The average treatment effect in the population as a whole is not identified, but under certain conditions this approach can be used to emulate a trial in the subset of individuals who were treated with the treatment of interest, in the subset of individuals who were treated with the treatment of interest but not with the comparator, or in the subset of individuals who were treated with both the treatment of interest and the active comparator. The Plausibility of the Comparability Conditions: We discuss whether the required conditions can be expected to hold in pharmacoepidemiologic research, with a particular focus on whether the conditions are plausible in situations where the standard analysis fails due to unmeasured confounding by access to health care or health seeking behaviors. Discussion: The conditions discussed in this paper may at best be approximately true. Investigators using active comparator designs to emulate trials with inactive comparators should exercise caution. PMID:27891526

  1. Feasibility of Free-breathing CCTA using 256-MDCT.

    PubMed

    Liu, Zhuo; Sun, Ye; Zhang, Zhuolu; Chen, Lei; Hong, Nan

    2016-07-01

    Usually, coronary computed tomography angiography (CCTA) is performed during breath-holding to reduce artifact caused by respiration. The objective of this study was to evaluate the feasibility of free-breathing CCTA compared to breath-holding using CT scanner with wide detector. To evaluate the feasibility of CCTA during free-breathing using a 256-MDCT. In 80 patients who underwent CCTA, 40 were performed during breath-holding (group A), and the remaining 40 during free-breathing (group B). The quality scores for coronary arteries were analyzed and defined as: 3 (excellent), 2 (good), and 1 (poor). The image noise, signal-to-noise ratio and effective radiation dose as well as the heart rate variation were compared. The noise, signal-to-noise ratio, and effective radiation dose were not significantly different between the 2 groups. The mean heart rate variation between planning and scanning for group A was 7 ± 7.6 bpm, and larger than 3 ± 2.6 bpm for group B (P = 0.012). Quality scores of the free-breathing group were better than those of the breath-holding group (group A: 2.55 ± 0.64, group B: 2.85 ± 0.36, P = 0.018). Free-breathing CCTA is feasible on wide detector CT scanner to provide acceptable image quality with reduced heart rate variation and better images for certain patients.

  2. Comparison between a new reconstruction algorithm (OPED) and filtered backprojection (FBP) for MDCT data

    NASA Astrophysics Data System (ADS)

    Renger, Bernhard; No"l, Peter B.; Tischenko, Oleg; Rummeny, Ernst J.; Hoeschen, Christoph

    2012-03-01

    Previously the Orthogonal Polynomial Expansion on the Disk (OPED) algorithm was presented. Further, in prototype experiments in combination with the CT D`or geometry feasibility was demonstrated. In this study we implemented OPED with a clinical Scanner, and evaluated the potential using phantom studies. All studies were acquired on a Siemens Somatom 64 (Erlangen, Germany) scanner, where raw projection data were reconstructed with the conventional FBP reconstruction and the OPED algorithm. OPED allows one to use fan beam geometry directly without any additional procedures such as interpolation or rebinning if using the CT D`or geometry. In particular, OPED describes an approximation of the image function as a sum of polynomials using Chebychev polynomials. For performance evaluation, the Catphan phantom 600 was imaged. OPED Images where reconstructed using C++ and MATLAB® .We measured uniformity, MTF and CNR for different dose levels and compared these to standard FBP images reconstructions with different filter kernels. The integration and interpretation of the MDCT projection data for the OPED algorithm was accomplished. Reconstruction time is about 6 s on Quad-Core 3 GHz Intel Xeon processor. Typical artifacts are reduced when applying OPED. Using OPED the MTF maintains constant over the whole FOV. Uniformity and CNR are equal compared to FBP. Advantages of OPED were demonstrated by applying the algorithm to projections images from a clinical MDCT scanner. In the future, we see OPED applications for low-dose or limited angle geometries to reduce the radiation dose while improving diagnostic quality of the reconstructed slices.

  3. Vascular involvement in periampullary tumors: MDCT, EUS, and CDU.

    PubMed

    Gusmini, S; Nicoletti, R; Martinenghi, C; Del Maschio, A

    2009-07-01

    In patients affected by periampullary tumors, surgical resection represents the only treatment with curative intent. Preoperative evaluation of vascular involvement is necessary to avoid surgical treatments unable of curative intent resection. The aim of our update article is to assess the performance of multidetector computed tomography (MDCT), endoscopic ultrasonography (EUS), and color Doppler ultrasonography (CDU) in the evaluation of vascular involvement of major peripancreatic vessels, in periampullary tumors, analyzing the current and past literature.

  4. Extramural venous invasion detected by MDCT as an adverse imaging feature for predicting synchronous metastases in T4 gastric cancer.

    PubMed

    Cheng, Jin; Wu, Jing; Ye, Yingjiang; Zhang, Chunfang; Zhang, Yinli; Wang, Yi

    2017-04-01

    Background Extramural venous invasion (EMVI) is defined histologically as the active invasion of tumor cells to the lumens of mesenteric vessels beyond the muscularis propria in advanced gastrointestinal cancer, resulting in distant metastases. Purpose To determine the association between synchronous metastatic disease in patients with T4 gastric cancer and EMVI detected on contrast-enhanced multiple-row detector computed tomography (MDCT). Material and Methods A total of 152 patients with T4 gastric carcinoma were retrospectively reviewed and divided into EMVI-positive and EMVI-negative groups where EMVI, as detected on MDCT, was defined as a tubular or nodular soft tissue thickening extending from the tumor along the vessels of the mesentery. Synchronous metastases were detected by MDCT and/or confirmed by postoperative diagnosis. Logistic regression analyses were performed to analyze the predictive factors of synchronous metastases in gastric cancer. Results Synchronous metastases were found in 47 of 152 (30.9%) patients with T4 gastric cancer. Thirty-one of 77 (40.3%) patients in the EMVI-positive group had evidence of metastases compared to 16 (21.3%) of 75 patients in the EMVI-negative group ( P = 0.019). Synchronous metastases were significantly associated with EMVI with an odds ratio (OR) of 2.250 (95% CI, 1.072-4.724). Conclusion EMVI-positive tumors, as an adverse imaging feature, were significantly associated with synchronous metastases in patients with T4 gastric cancer.

  5. Comparing Learning from Observing and from Human Tutoring

    ERIC Educational Resources Information Center

    Muldner, Kasia; Lam, Rachel; Chi, Michelene T. H.

    2014-01-01

    A promising instructional approach corresponds to" learning by observing others learn" (i.e., by watching tutorial dialogue between a tutor and tutee). However, more work is needed to understand this approach's pedagogical utility. Thus, in 2 experiments we compared student learning from collaborative observation of dialogue with 2 other…

  6. Data compression in wireless sensors network using MDCT and embedded harmonic coding.

    PubMed

    Alsalaet, Jaafar K; Ali, Abduladhem A

    2015-05-01

    One of the major applications of wireless sensors networks (WSNs) is vibration measurement for the purpose of structural health monitoring and machinery fault diagnosis. WSNs have many advantages over the wired networks such as low cost and reduced setup time. However, the useful bandwidth is limited, as compared to wired networks, resulting in relatively low sampling. One solution to this problem is data compression which, in addition to enhancing sampling rate, saves valuable power of the wireless nodes. In this work, a data compression scheme, based on Modified Discrete Cosine Transform (MDCT) followed by Embedded Harmonic Components Coding (EHCC) is proposed to compress vibration signals. The EHCC is applied to exploit harmonic redundancy present is most vibration signals resulting in improved compression ratio. This scheme is made suitable for the tiny hardware of wireless nodes and it is proved to be fast and effective. The efficiency of the proposed scheme is investigated by conducting several experimental tests.

  7. MDCT imaging of the stomach: advances and applications.

    PubMed

    Nagpal, Prashant; Prakash, Anjali; Pradhan, Gaurav; Vidholia, Aditi; Nagpal, Nishant; Saboo, Sachin S; Kuehn, David M; Khandelwal, Ashish

    2017-01-01

    The stomach may be involved by a myriad of pathologies ranging from benign aetiologies like inflammation to malignant aetiologies like carcinoma or lymphoma. Multidetector CT (MDCT) of the stomach is the first-line imaging for patients with suspected gastric pathologies. Conventionally, CT imaging had the advantage of simultaneous detection of the mural and extramural disease extent, but advances in MDCT have allowed mucosal assessment by virtual endoscopy (VE). Also, better three-dimensional (3D) post-processing techniques have enabled more robust and accurate pre-operative planning in patients undergoing gastrectomy and even predict the response to surgery for patients undergoing laparoscopic sleeve gastrectomy for weight loss. The ability of CT to obtain stomach volume (for bariatric surgery patients) and 3D VE images depends on various patient and protocol factors that are important for a radiologist to understand. We review the appropriate CT imaging protocol in the patients with suspected gastric pathologies and highlight the imaging pearls of various gastric pathologies on CT and VE.

  8. MDCT of hand and wrist infections: emphasis on compartmental anatomy.

    PubMed

    Ahlawat, S; Corl, F M; LaPorte, D M; Fishman, E K; Fayad, L M

    2017-04-01

    Hand and wrist infections can present with a spectrum of manifestations ranging from cellulitis to deep-space collections. The various infectious processes can be categorised as superficial or deep infections based on their respective locations relative to the tendons. Superficial hand infections are located superficial to the tendons and are comprised of cellulitis, lymphangitis, paronychia, pulp-space infections, herpetic whitlow, and include volar as well as dorsal subcutaneous abscesses. Deep hand infections are located deep to the tendon sheaths and include synovial space infections, such as infectious tenosynovitis, deep fascial space infections, septic arthritis, necrotising fasciitis, and osteomyelitis. Knowledge of hand and wrist compartmental anatomy is essential for the accurate diagnosis and management of hand infections. Although early and superficial infections of the hand may respond to non-surgical management, most hand infections are surgical emergencies. Multidetector computed tomography (MDCT), with its muliplanar reformation (MPR) and three-dimensional (3D) capabilities, is a powerful tool in the emergency setting for the evaluation of acute hand and wrist pathology. The clinical and imaging features of hand and wrist infections as evident on MDCT will be reviewed with emphasis on contiguous and closed synovial and deep fascial spaces. Knowledge of hand compartmental anatomy enables accurate characterisation of the infectious process and localise the extent of disease in the acute setting.

  9. Mixed-radix Algorithm for the Computation of Forward and Inverse MDCT

    PubMed Central

    Wu, Jiasong; Shu, Huazhong; Senhadji, Lotfi; Luo, Limin

    2008-01-01

    The modified discrete cosine transform (MDCT) and inverse MDCT (IMDCT) are two of the most computational intensive operations in MPEG audio coding standards. A new mixed-radix algorithm for efficient computing the MDCT/IMDCT is presented. The proposed mixed-radix MDCT algorithm is composed of two recursive algorithms. The first algorithm, called the radix-2 decimation in frequency (DIF) algorithm, is obtained by decomposing an N-point MDCT into two MDCTs with the length N/2. The second algorithm, called the radix-3 decimation in time (DIT) algorithm, is obtained by decomposing an N-point MDCT into three MDCTs with the length N/3. Since the proposed MDCT algorithm is also expressed in the form of a simple sparse matrix factorization, the corresponding IMDCT algorithm can be easily derived by simply transposing the matrix factorization. Comparison of the proposed algorithm with some existing ones shows that our proposed algorithm is more suitable for parallel implementation and especially suitable for the layer III of MPEG-1 and MPEG-2 audio encoding and decoding. Moreover, the proposed algorithm can be easily extended to the multidimensional case by using the vector-radix method. PMID:21258639

  10. Is multidetector computed tomography comparable to magnetic resonance imaging for assessment of lumbar foraminal stenosis?

    PubMed

    Kang, Woo Young; Ahn, Joong Mo; Lee, Joon Woo; Lee, Eugene; Bae, Yun Jung; Seo, Jiwoon; Kim, Junghoon; Kang, Heung Sik

    2017-02-01

    Background Both multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) are used for assessment of lumbar foraminal stenosis (LFS). Therefore, it is relevant to assess agreement between these imaging modalities. Purpose To determine intermodality, inter-, and intra-observer agreement for assessment of LFS on MDCT and MRI. Material and Methods A total of 120 foramina in 20 patients who visited our institution in January and February 2014 were evaluated by six radiologists with different levels of experience. Radiologists evaluated presence and severity of LFS on sagittal CT and MR images according to a previously published LFS grading system. Intermodality agreement was analyzed by using weighted kappa statistics, while inter- and intra-observer agreement were analyzed by using intraclass correlation coefficients (ICCs) and kappa statistics. Results Overall intermodality agreement was moderate to good (kappa, 0.478-0.765). In particular, two professors and one fellow tended to overestimate the degree of LFS on CT compared with MRI. For inter-observer agreement of all six observers, ICCs indicated excellent agreement for both CT (0.774) and MRI (0.771), while Fleiss' kappa values showed moderate agreement for CT (0.482) and MRI (0.575). There was better agreement between professors and fellows compared with residents. For intra-observer agreement, ICCs indicated excellent agreement, while kappa values showed good to excellent agreement for both CT and MRI. Conclusion MDCT was comparable to MRI for diagnosis and assessment of LFS, especially for experienced observers. However, there was a tendency to overestimate the degree of LFS on MDCT compared with MRI.

  11. "Lies, damned lies ..." and observational studies in comparative effectiveness research.

    PubMed

    Albert, Richard K

    2013-06-01

    A new federal initiative has allocated $1.1 billion to comparative effectiveness research, and many have emphasized the importance of including observational studies in this effort. The rationale for using observational studies to assess comparative effectiveness is based on concerns that randomized controlled trials (RCTs) are not "real world" because they enroll homogeneous patient populations, measure study outcomes that are not important to patients, use protocols that are overly complex, are conducted in specialized centers, and use study treatments that are not consistent with usual care, and that RCTs are not always feasible because of a lack of equipoise, the need to assess delayed endpoints, and concerns that they take years to complete and are expensive. This essay questions the validity of each of these proposed limitations, summarizes concerns raised about the accuracy of results generated by observational studies, provides some examples of discrepancies between results of observational studies and RCTs that pertain to pulmonary and critical care, and suggests that using observational studies for comparative effectiveness research may increase rather than decrease the cost of health care and may harm patients.

  12. A Comparative Study of Cloud Observation between Instrumental Measurements and Visual Observations

    NASA Astrophysics Data System (ADS)

    Park, Y. S.; Jeong, J. Y.; Park, D. O.; Kang, J. J.; Choi, B. C.

    2014-12-01

    The microphysical observations of clouds have been performed by human observers who record the amount, height, and type of cloud. However, the observational methods of clouds by human observers have their limitations due to its difficulties in the punctuality and weakness of assessment. The Automatic Cloud Observation System(ACOS) has been developed by NIMR to obtain continuous informationof the amount and height of clouds. A set of ACOS is composed of two cameras and the amounts and heights of clouds are retrieved from the sky images. Four sets of the ACOS were installed during last 4 years at four locations in South Korea. They are compared with cloud observation data from visual observations and instrumental measurements using ceilometers, radiometers, and another camera-type instrument named "Sky View". Recent two-year observation data are analyzed, focused on the differences of cloud amounts and heights between cloud observation methods.

  13. Arterial double-contrast dual-energy MDCT: in-vivo rabbit atherosclerosis with iodinated nanoparticles and gadolinium agents

    NASA Astrophysics Data System (ADS)

    Carmi, Raz; Kafri, Galit; Altman, Ami; Goshen, Liran; Planer, David; Sosna, Jacob

    2010-03-01

    An in-vivo feasibility study of potentially improved atherosclerosis CT imaging is presented. By administration of two different contrast agents to rabbits with induced atherosclerotic plaques we aim at identifying both soft plaque and vessel lumen simultaneously. Initial injection of iodinated nanoparticle (INP) contrast agent (N1177 - Nanoscan Imaging), two to four hours before scan, leads to its later accumulation in macrophage-rich soft plaque, while a second gadolinium contrast agent (Magnevist) injected immediately prior to the scan blends with the aortic blood. The distinction between the two agents in a single scan is achieved with a double-layer dual-energy MDCT (Philips Healthcare) following material separation analysis using the reconstructed images of the different x-ray spectra. A single contrast agent injection scan, where only INP was injected two hours prior to the scan, was compared to a double-contrast scan taken four hours after INP injection and immediately after gadolinium injection. On the single contrast agent scan we observed along the aorta walls, localized iodine accumulation which can point on INP uptake by atherosclerotic plaque. In the double-contrast scan the gadolinium contributes a clearer depiction of the vessel lumen in addition to the lasting INP presence. The material separation shows a good correlation to the pathologies inferred from the conventional CT images of the two different scans while performing only a single scan prevents miss-registration problems and reduces radiation dose. These results suggest that a double-contrast dual-energy CT may be used for advanced clinical diagnostic applications.

  14. Polyarteritis nodosa: MDCT as a 'One-Stop Shop' Modality for Whole-Body Arterial Evaluation

    SciTech Connect

    Tsai, W.-L.; Tsai, I-C.; Lee Tain; Hsieh, C.-W.

    2008-07-15

    Polyarteritis nodosa is a rare disease, which is characterized by aneurysm formation and occlusion in the arteries of multiple systems. Due to its extensive involvement, whole-body evaluation is necessary for diagnosis and treatment monitoring. We report a case of polyarteritis nodosa using multidetector-row computed tomography (MDCT) as a 'one-stop shop' modality for whole-body arterial evaluation. With precise protocol design, MDCT can be used as a reliable noninvasive modality providing comprehensive whole-body arterial evaluation.

  15. Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

    SciTech Connect

    Gomez-Cardona, Daniel; Nagle, Scott K.; Li, Ke; Chen, Guang-Hong; Robinson, Terry E.

    2015-10-15

    Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiation dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo{sup TM}, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low radiation dose

  16. Halo Coronal Mass Ejections: Comparing Observations and Models

    NASA Technical Reports Server (NTRS)

    Gilbert, Holly; Orlove, Matthew; SaintCyr, O.; Mays, L.; Gopalswamy, N.

    2011-01-01

    Since 1996, the SOHO LASCO coronagraphs have detected "halo" CMEs that appear to be directed toward Earth, but information about the size and speed of these events seen face-on has been limited. From a single vantage point along the Sun-Earth line, the primary limitation has been ambiguity in fitting the cone model (or other forward-modeling techniques, e.g., Thernisian et al., 2006). But in the past few years, the STEREO mission has provided a view of Earth-directed events from the side. These events offer the opportunity to compare measurements (width and speed) of halo CMEs observed by STEREO with models that derive halo CME properties. We report here results of such a comparison on a large sample of LASCO CMEs in the STEREO era.

  17. Comparing soil moisture memory in satellite observations and models

    NASA Astrophysics Data System (ADS)

    Stacke, Tobias; Hagemann, Stefan; Loew, Alexander

    2013-04-01

    A major obstacle to a correct parametrization of soil processes in large scale global land surface models is the lack of long term soil moisture observations for large parts of the globe. Currently, a compilation of soil moisture data derived from a range of satellites is released by the ESA Climate Change Initiative (ECV_SM). Comprising the period from 1978 until 2010, it provides the opportunity to compute climatological relevant statistics on a quasi-global scale and to compare these to the output of climate models. Our study is focused on the investigation of soil moisture memory in satellite observations and models. As a proxy for memory we compute the autocorrelation length (ACL) of the available satellite data and the uppermost soil layer of the models. Additional to the ECV_SM data, AMSR-E soil moisture is used as observational estimate. Simulated soil moisture fields are taken from ERA-Interim reanalysis and generated with the land surface model JSBACH, which was driven with quasi-observational meteorological forcing data. The satellite data show ACLs between one week and one month for the greater part of the land surface while the models simulate a longer memory of up to two months. Some pattern are similar in models and observations, e.g. a longer memory in the Sahel Zone and the Arabian Peninsula, but the models are not able to reproduce regions with a very short ACL of just a few days. If the long term seasonality is subtracted from the data the memory is strongly shortened, indicating the importance of seasonal variations for the memory in most regions. Furthermore, we analyze the change of soil moisture memory in the different soil layers of the models to investigate to which extent the surface soil moisture includes information about the whole soil column. A first analysis reveals that the ACL is increasing for deeper layers. However, its increase is stronger in the soil moisture anomaly than in its absolute values and the first even exceeds the

  18. Comparative Structure of Saturn's Rings from Cassini Radio Occultation Observations

    NASA Astrophysics Data System (ADS)

    Marouf, Essam A.; French, R. G.; Rappaport, N. J.; McGhee, C. A.; Wong, K.; Thomson, F. S.; Anabtawi, A.

    2007-10-01

    Radio occultations of Saturn's rings during the Cassini prime mission fall into three main groups, depending on the rings opening angle B. The first is a set of eight diametric occultations completed early in the mission (March-September/2005) when |B| was relatively large (19.5 to 23.5°). They permitted multiple-longitude profiling of relatively optically thick ring features, revealing detailed structure of enigmatic Ring B. The second is to be completed late in the mission when the rings are relatively closed (|B| < 10°). They will provide enhanced sensitivity to tenuous ring material, hence complementary information about small optical depth structure. Bridging the two groups is a third composed of two specially designed occultations recently completed (May-June/2007). They capture the intermediate range |B| 15°. Because the rings were still reasonably open, much of the structure was profiled. The different occultation geometry from the diametric group provided enhanced sensitivity to bending waves and other inclined features. We comparatively consider variability (or lack of) of observed ring structure with B and longitude. The variability when present can be true (dynamically forced features) or apparent (azimuthal asymmetry due to preferentially aligned gravitational wakes). The multiple-longitude coverage provides rich characterization of the true variability, including remarkable variations in the morphology of gap-embedded ringlets in Ring C, clear variations in the width of gaps in the Cassini Division, wavelike features in Ring C (the "Rosen Waves"), classical satellite wake profiles due to Pan, in addition to many density and few bending waves. For the apparent asymmetry, observed optical depth variations with B, viewing geometry, and wavelength constrain physical properties of the rings microstructure (particle sizes, particle-cluster sizes and orientation, spatial cluster density, vertical ring profile and physical thickness, ...). Complementary

  19. Comparing the incomparable: hemodialysis versus peritoneal dialysis in observational studies.

    PubMed

    Foley, Robert N

    2004-01-01

    A randomized trial comparing survival in hemodialysis and peritoneal dialysis remains a utopian aspiration. Dialysis is still relatively rare on a population basis, and a natural tension exists between desirability and feasibility in terms of quality of evidence. In practice, it is very difficult to perform prospective comparisons with large groups of contemporary representative subjects, and much of the literature comes from retrospective national registries. This article considers several questions to address when trying to compare the outcomes of peritoneal dialysis and hemodialysis. Prognostic similarity at baseline is a fundamental issue. Traditionally, adjustment for known prognostic factors has been used in an attempt to minimize the bias caused by nonrandom treatment assignment. Propensity scores have been suggested to be superior, and matched-case analysis may also be a useful method for comparison. Other questions include, when, in relation to starting dialysis, to start the observation clock; the definition and handling of switches of dialysis therapy; and the decision to censor at transplantation. Finally, comparisons are complicated by hazards ratios that vary over time, and time-segmented analysis is obligatory. Many types of analytical approaches are needed to begin to appreciate outcome disparities between dialysis therapies.

  20. Three-dimensional reconstruction of upper airways from MDCT

    NASA Astrophysics Data System (ADS)

    Perchet, Diane; Fetita, Catalin; Preteux, Francoise

    2005-03-01

    Under the framework of clinical respiratory investigation, providing accurate modalities for morpho-functional analysis is essential for diagnosis improvement, surgical planning and follow-up. This paper focuses on the upper airways investigation and develops an automated approach for 3D mesh reconstruction from MDCT acquisitions. In order to overcome the difficulties related to the complex morphology of the upper airways and to the image gray level heterogeneity of the airway lumens and thin bony septa, the proposed 3D reconstruction methodology combines 2D segmentation and 3D surface regularization approaches. The segmentation algorithm relies on mathematical morphology theory and provides airway lumen robust discrimination from the surrounding tissues, while preserving the connectivity relationship between the different anatomical structures. The 3D regularization step uses an energy-based modeling in order to achieve a smooth and well-fitted 3D surface of the upper airways. An accurate 3D mesh representation of the reconstructed airways makes it possible to develop specific clinical applications such as virtual endoscopy, surgical planning and computer assisted intervention. In addition, building up patient-specific 3D models of upper airways is highly valuable for the study and design of inhaled medication delivery via computational fluid dynamics (CFD) simulations.

  1. Accurate 3D quantification of the bronchial parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Saragaglia, A.; Fetita, C.; Preteux, F.; Brillet, P. Y.; Grenier, P. A.

    2005-08-01

    The assessment of bronchial reactivity and wall remodeling in asthma plays a crucial role in better understanding such a disease and evaluating therapeutic responses. Today, multi-detector computed tomography (MDCT) makes it possible to perform an accurate estimation of bronchial parameters (lumen and wall areas) by allowing a quantitative analysis in a cross-section plane orthogonal to the bronchus axis. This paper provides the tools for such an analysis by developing a 3D investigation method which relies on 3D reconstruction of bronchial lumen and central axis computation. Cross-section images at bronchial locations interactively selected along the central axis are generated at appropriate spatial resolution. An automated approach is then developed for accurately segmenting the inner and outer bronchi contours on the cross-section images. It combines mathematical morphology operators, such as "connection cost", and energy-controlled propagation in order to overcome the difficulties raised by vessel adjacencies and wall irregularities. The segmentation accuracy was validated with respect to a 3D mathematically-modeled phantom of a pair bronchus-vessel which mimics the characteristics of real data in terms of gray-level distribution, caliber and orientation. When applying the developed quantification approach to such a model with calibers ranging from 3 to 10 mm diameter, the lumen area relative errors varied from 3.7% to 0.15%, while the bronchus area was estimated with a relative error less than 5.1%.

  2. Shading correction for on-board cone-beam CT in radiation therapy using planning MDCT images

    SciTech Connect

    Niu Tianye; Sun, Mingshan; Star-Lack, Josh; Gao Hewei; Fan Qiyong; Zhu Lei

    2010-10-15

    Purpose: Applications of cone-beam CT (CBCT) to image-guided radiation therapy (IGRT) are hampered by shading artifacts in the reconstructed images. These artifacts are mainly due to scatter contamination in the projections but also can result from uncorrected beam hardening effects as well as nonlinearities in responses of the amorphous silicon flat panel detectors. While currently, CBCT is mainly used to provide patient geometry information for treatment setup, more demanding applications requiring high-quality CBCT images are under investigation. To tackle these challenges, many CBCT correction algorithms have been proposed; yet, a standard approach still remains unclear. In this work, we propose a shading correction method for CBCT that addresses artifacts from low-frequency projection errors. The method is consistent with the current workflow of radiation therapy. Methods: With much smaller inherent scatter signals and more accurate detectors, diagnostic multidetector CT (MDCT) provides high quality CT images that are routinely used for radiation treatment planning. Using the MDCT image as ''free'' prior information, we first estimate the primary projections in the CBCT scan via forward projection of the spatially registered MDCT data. Since most of the CBCT shading artifacts stem from low-frequency errors in the projections such as scatter, these errors can be accurately estimated by low-pass filtering the difference between the estimated and raw CBCT projections. The error estimates are then subtracted from the raw CBCT projections. Our method is distinct from other published correction methods that use the MDCT image as a prior because it is projection-based and uses limited patient anatomical information from the MDCT image. The merit of CBCT-based treatment monitoring is therefore retained. Results: The proposed method is evaluated using two phantom studies on tabletop systems. On the Catphan(c)600 phantom, our approach reduces the reconstruction error

  3. Four- and Eight-Channel Aortoiliac CT Angiography: A Comparative Study

    SciTech Connect

    Karcaaltincaba, Musturay Foley, Dennis

    2005-04-15

    Purpose. To compare performance parameters, contrast material load and radiation dose in a patient cohort having aortoiliac CT angiography using 4- and 8-channel multidetector CT (MDCT) systems. Methods. Eighteen patients with abdominal aortic aneurysms underwent initial 4-channel and follow-up 8-channel MDCT angiography. Both the 4- and 8-channel MDCT systems utilized a matrix detector of 16 x 1.25 mm rows. Scan coverage included the abdominal aorta and iliac arteries to the level of the proximal femoral arteries. For 4-channel MDCT, nominal slice thickness and beam pitch were 1.25 mm and 1.5, respectively, and for 8-channel MDCT they were 1.25 mm and 1.35 or 1.65 respectively. Scan duration, iodinated contrast material load and mean aortoiliac attenuation were compared retrospectively. Comparative radiation dose measurements for 4- and 8-channel MDCT were obtained using a multiple scan average dose technique on an abdominal phantom. Results. Compared with 4-channel MDCT, 8-channel MDCT aortoiliac angiography was performed with equivalent collimation, decreased contrast load (mean 45% decrease: 144 ml versus 83 ml of 300 mg iodine/ml contrast material) and decreased acquisition time (mean 51% shorter: 34.4 sec versus 16.9 sec) without a significant change in mean aortic enhancement (299 HU versus 300 HU, p > 0.05). Radiation dose was 2 rad for the 4-channel system and 2/1.5 rad for the 8-channel system at 1.35/1.65 pitch respectively. Conclusion. Compared with 4-channel MDCT, aortoiliac CT angiography with 8-channel MDCT produces equivalent z-axis resolution with decreased contrast load and acquisition time without increased radiation exposure.

  4. Robust extraction of the aorta and pulmonary artery from 3D MDCT image data

    NASA Astrophysics Data System (ADS)

    Taeprasartsit, Pinyo; Higgins, William E.

    2010-03-01

    Accurate definition of the aorta and pulmonary artery from three-dimensional (3D) multi-detector CT (MDCT) images is important for pulmonary applications. This work presents robust methods for defining the aorta and pulmonary artery in the central chest. The methods work on both contrast enhanced and no-contrast 3D MDCT image data. The automatic methods use a common approach employing model fitting and selection and adaptive refinement. During the occasional event that more precise vascular extraction is desired or the method fails, we also have an alternate semi-automatic fail-safe method. The semi-automatic method extracts the vasculature by extending the medial axes into a user-guided direction. A ground-truth study over a series of 40 human 3D MDCT images demonstrates the efficacy, accuracy, robustness, and efficiency of the methods.

  5. A new approach to the assessment of lumen visibility of coronary artery stent at various heart rates using 64-slice MDCT

    PubMed Central

    Groen, J. M.; van Ooijen, P. M. A.; Oudkerk, M.

    2007-01-01

    Coronary artery stent lumen visibility was assessed as a function of cardiac movement and temporal resolution with an automated objective method using an anthropomorphic moving heart phantom. Nine different coronary stents filled with contrast fluid and surrounded by fat were scanned using 64-slice multi-detector computed tomography (MDCT) at 50–100 beats/min with the moving heart phantom. Image quality was assessed by measuring in-stent CT attenuation and by a dedicated tool in the longitudinal and axial plane. Images were scored by CT attenuation and lumen visibility and compared with theoretical scoring to analyse the effect of multi-segment reconstruction (MSR). An average increase in CT attenuation of 144 ± 59 HU and average diminished lumen visibility of 29 ± 12% was observed at higher heart rates in both planes. A negative correlation between image quality and heart rate was non-significant for the majority of measurements (P > 0.06). No improvement of image quality was observed in using MSR. In conclusion, in-stent CT attenuation increases and lumen visibility decreases at increasing heart rate. Results obtained with the automated tool show similar behaviour compared with attenuation measurements. Cardiac movement during data acquisition causes approximately twice as much blurring compared with the influence of temporal resolution on image quality. Electronic supplementary material The online version of this article (doi:10.1007/s00330-007-0568-8) contains supplementary material, which is available to authorized users. PMID:17429648

  6. Pelvic ultrasound immediately following MDCT in female patients with abdominal/pelvic pain: is it always necessary?

    PubMed

    Yitta, Silaja; Mausner, Elizabeth V; Kim, Alice; Kim, Danny; Babb, James S; Hecht, Elizabeth M; Bennett, Genevieve L

    2011-10-01

    To determine the added value of reimaging the female pelvis with ultrasound (US) immediately following multidetector CT (MDCT) in the emergent setting. CT and US exams of 70 patients who underwent MDCT for evaluation of abdominal/pelvic pain followed by pelvic ultrasound within 48 h were retrospectively reviewed by three readers. Initially, only the CT images were reviewed followed by evaluation of CT images in conjunction with US images. Diagnostic confidence was recorded for each reading and an exact Wilcoxon signed rank test was performed to compare the two. Changes in diagnosis based on combined CT and US readings versus CT readings alone were identified. Confidence intervals (95%) were derived for the percentage of times US reimaging can be expected to lead to a change in diagnosis relative to the diagnosis based on CT interpretation alone. Ultrasound changed the diagnosis for the ovaries/adnexa 8.1% of the time (three reader average); the majority being cases of a suspected CT abnormality found to be normal on US. Ultrasound changed the diagnosis for the uterus 11.9% of the time (three reader average); the majority related to the endometrial canal. The 95% confidence intervals for the ovaries/adnexa and uterus were 5-12.5% and 8-17%, respectively. Ten cases of a normal CT were followed by a normal US with 100% agreement across all three readers. Experienced readers correctly diagnosed ruptured ovarian cysts and tubo-ovarian abscesses (TOA) based on CT alone with 100% agreement. US reimaging after MDCT of the abdomen and pelvis is not helpful: (1) following a normal CT of the pelvic organs or (2) when CT findings are diagnostic and/or characteristic of certain entities such as ruptured cysts and TOA. Reimaging with ultrasound is warranted for (1) less-experienced readers to improve diagnostic confidence or when CT findings are not definitive, (2) further evaluation of suspected endometrial abnormalities. A distinction should be made between the need for

  7. Comparing Simulations and Observations of Reionization-Epoch Galaxies

    NASA Astrophysics Data System (ADS)

    Dave, Romeel; Finlator, Kristian

    2006-05-01

    We propose to test and constrain models of early galaxy formation through comparisons with observations of reionization-epoch (z>6) galaxies observed using Spitzer. The goals are to (1) Make predictions for z>6 objects using state-of-the-art cosmological hydrodynamic simulations of galaxy formation tailored to study the reionization epoch; (2) Develop a publicly-available tool called SPOC designed to obtain detailed constraints on physical properties of observed galaxies through comparisons with simulated galaxy catalogs; and (3) Use SPOC to test and constrain models of galaxy formation through comparisons with rapidly- advancing observations in the new frontier of early universe studies. The results of this study will yield deeper insights into the galaxy formation process at these mostly unexplored epochs, with implications for understanding the formation of massive galaxies, studying the topology and evolution of IGM reionization, and designing future surveys to detect first objects. The SPOC tool will facilitate a closer connection between observations and theory by enabling the community to interpret data within the framework of current hierarchical structure formation models, in turn providing detailed tests of these models that is essential for driving the field forward.

  8. Whistler Observations on DEMETER Compared with FWM Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Compston, A. J.; Cohen, M.; Lehtinen, N. G.; Inan, U.; Linscott, I.; Parrot, M.

    2012-12-01

    Terrestrial Very Low Frequency (VLF) electromagnetic radiation, which plays an important role in the Van Allen radiation belts, is injected into Earth's plasmasphere from two primary sources: man-made VLF transmitters and lightning discharges. Recent studies have called into question some of the numerical models that simulate radiation injection into the plasmasphere by VLF transmitters: specifically, said models have been shown to overestimate the electromagnetic fields by at least 10 dB when compared to satellite measurements. In this study, we compared lightning-induced whistlers on the low earth orbiting DEMETER satellite with an electromagnetic, frequency domain Full Wave Method (FWM) finite element numerical code. By correlating lightning discharge time, location, and peak current data from the National Lightning Detection Network (NLDN) in the United States with burst mode electromagnetic field measurements of the whistlers on DEMETER, we were able to make an accurate estimate of the field strengths on DEMETER from the FWM simulation results for over 5000 lightning discharges over more than 10 different DEMETER passes during both the day and night. The FWM field estimates match the DEMETER measurements to less than 5 dB.

  9. Three-dimensional MDCT angiography of splanchnic arteries: pearls and pitfalls.

    PubMed

    Dohan, A; Dautry, R; Guerrache, Y; Fargeaudou, Y; Boudiaf, M; Le Dref, O; Sirol, M; Soyer, P

    2015-02-01

    Fast scanning along with high resolution of multidetector computed tomography (MDCT) have expanded the role of non-invasive imaging of splanchnic arteries. Advancements in both MDCT scanner technology and three-dimensional (3D) imaging software provide a unique opportunity for non-invasive investigation of splanchnic arteries. Although standard axial computed tomography (CT) images allow identification of splanchnic arteries, visualization of small or distal branches is often limited. Similarly, a comprehensive assessment of the complex anatomy of splanchnic arteries is often beyond the reach of axial images. However, the submillimeter collimation that can be achieved with MDCT scanners now allows the acquisition of true isotropic data so that a high spatial resolution is now maintained in any imaging plane and in 3D mode. This ability to visualize the complex network of splanchnic arteries using 3D rendering and multiplanar reconstruction is of major importance for an optimal analysis in many situations. The purpose of this review is to discuss and illustrate the role of 3D MDCT angiography in the detection and assessment of abnormalities of splanchnic arteries as well as the limitations of the different reconstruction techniques.

  10. US and MDCT diagnosis of a rare cause of haematuria in children: Posterior nutcracker syndrome.

    PubMed

    Ozel, A; Tufaner, O; Kaya, E; Maldur, V

    2011-06-01

    Posterior nutcracker syndrome is caused by compression of the left renal vein between the abdominal aorta and the vertebral column. We present the case of a 14-year-old girl with vague left loin pain, mild haematuria and proteinuria. Diagnosis of this rare syndrome was achieved using color Doppler US and multidetector computed tomography (MDCT) angiography.

  11. Comparing Observed Hurricane Conditions Against Potential Future Climate Change Influences

    NASA Astrophysics Data System (ADS)

    Graham, W. D.

    2012-12-01

    Climate Adaptation Science Investigators: (CASI) is to advance and apply NASA's scientific expertise and products to develop climate adaptation strategies that support NASA's overall mission by minimizing risks to each center's operations, physical assets, and personnel. Using Hurricane Katrina observations as a baseline, we use ADCIRC to model surge extent with simple modifications of the storm track. We examine two time now (T0) scenarios of present-day climatological factors: 1) translating the 2005 path 7 km west; and 2) rotating the approach angle from due-north to WNW. Second, we examine two future time scenarios (TX) by infusing climate change conditions, such as sea level rise and increased storm intensity, into a T0 baseline to assess future impacts. The primary goal of this work entails planning and protecting NASA assets and infrastructure. The adjacent communities, state and local emergency managers, gain benefit from this NASA work as data and analysis includes the surrounding geography.

  12. Effects of computing parameters and measurement locations on the estimation of 3D NPS in non-stationary MDCT images.

    PubMed

    Miéville, Frédéric A; Bolard, Gregory; Bulling, Shelley; Gudinchet, François; Bochud, François O; Verdun, François R

    2013-11-01

    The goal of this study was to investigate the impact of computing parameters and the location of volumes of interest (VOI) on the calculation of 3D noise power spectrum (NPS) in order to determine an optimal set of computing parameters and propose a robust method for evaluating the noise properties of imaging systems. Noise stationarity in noise volumes acquired with a water phantom on a 128-MDCT and a 320-MDCT scanner were analyzed in the spatial domain in order to define locally stationary VOIs. The influence of the computing parameters in the 3D NPS measurement: the sampling distances bx,y,z and the VOI lengths Lx,y,z, the number of VOIs NVOI and the structured noise were investigated to minimize measurement errors. The effect of the VOI locations on the NPS was also investigated. Results showed that the noise (standard deviation) varies more in the r-direction (phantom radius) than z-direction plane. A 25 × 25 × 40 mm(3) VOI associated with DFOV = 200 mm (Lx,y,z = 64, bx,y = 0.391 mm with 512 × 512 matrix) and a first-order detrending method to reduce structured noise led to an accurate NPS estimation. NPS estimated from off centered small VOIs had a directional dependency contrary to NPS obtained from large VOIs located in the center of the volume or from small VOIs located on a concentric circle. This showed that the VOI size and location play a major role in the determination of NPS when images are not stationary. This study emphasizes the need for consistent measurement methods to assess and compare image quality in CT.

  13. Semi-automatic central-chest lymph-node definition from 3D MDCT images

    NASA Astrophysics Data System (ADS)

    Lu, Kongkuo; Higgins, William E.

    2010-03-01

    Central-chest lymph nodes play a vital role in lung-cancer staging. The three-dimensional (3D) definition of lymph nodes from multidetector computed-tomography (MDCT) images, however, remains an open problem. This is because of the limitations in the MDCT imaging of soft-tissue structures and the complicated phenomena that influence the appearance of a lymph node in an MDCT image. In the past, we have made significant efforts toward developing (1) live-wire-based segmentation methods for defining 2D and 3D chest structures and (2) a computer-based system for automatic definition and interactive visualization of the Mountain central-chest lymph-node stations. Based on these works, we propose new single-click and single-section live-wire methods for segmenting central-chest lymph nodes. The single-click live wire only requires the user to select an object pixel on one 2D MDCT section and is designed for typical lymph nodes. The single-section live wire requires the user to process one selected 2D section using standard 2D live wire, but it is more robust. We applied these methods to the segmentation of 20 lymph nodes from two human MDCT chest scans (10 per scan) drawn from our ground-truth database. The single-click live wire segmented 75% of the selected nodes successfully and reproducibly, while the success rate for the single-section live wire was 85%. We are able to segment the remaining nodes, using our previously derived (but more interaction intense) 2D live-wire method incorporated in our lymph-node analysis system. Both proposed methods are reliable and applicable to a wide range of pulmonary lymph nodes.

  14. A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

    SciTech Connect

    Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

    2013-07-01

    A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C{sub 1} continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

  15. A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

    NASA Astrophysics Data System (ADS)

    Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

    2013-07-01

    A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C1 continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

  16. In-Vivo Assessment of Femoral Bone Strength Using Finite Element Analysis (FEA) Based on Routine MDCT Imaging: A Preliminary Study on Patients with Vertebral Fractures

    PubMed Central

    Liebl, Hans; Garcia, Eduardo Grande; Holzner, Fabian; Noel, Peter B.; Burgkart, Rainer; Rummeny, Ernst J.; Baum, Thomas; Bauer, Jan S.

    2015-01-01

    Purpose To experimentally validate a non-linear finite element analysis (FEA) modeling approach assessing in-vitro fracture risk at the proximal femur and to transfer the method to standard in-vivo multi-detector computed tomography (MDCT) data of the hip aiming to predict additional hip fracture risk in subjects with and without osteoporosis associated vertebral fractures using bone mineral density (BMD) measurements as gold standard. Methods One fresh-frozen human femur specimen was mechanically tested and fractured simulating stance and clinically relevant fall loading configurations to the hip. After experimental in-vitro validation, the FEA simulation protocol was transferred to standard contrast-enhanced in-vivo MDCT images to calculate individual hip fracture risk each for 4 subjects with and without a history of osteoporotic vertebral fractures matched by age and gender. In addition, FEA based risk factor calculations were compared to manual femoral BMD measurements of all subjects. Results In-vitro simulations showed good correlation with the experimentally measured strains both in stance (R2 = 0.963) and fall configuration (R2 = 0.976). The simulated maximum stress overestimated the experimental failure load (4743 N) by 14.7% (5440 N) while the simulated maximum strain overestimated by 4.7% (4968 N). The simulated failed elements coincided precisely with the experimentally determined fracture locations. BMD measurements in subjects with a history of osteoporotic vertebral fractures did not differ significantly from subjects without fragility fractures (femoral head: p = 0.989; femoral neck: p = 0.366), but showed higher FEA based risk factors for additional incident hip fractures (p = 0.028). Conclusion FEA simulations were successfully validated by elastic and destructive in-vitro experiments. In the subsequent in-vivo analyses, MDCT based FEA based risk factor differences for additional hip fractures were not mirrored by according BMD measurements. Our

  17. Addressing Informatics Barriers to Conducting Observational Comparative Effectiveness Research: A Comparative Case Analysis

    ERIC Educational Resources Information Center

    Boone, Christopher P. D.

    2013-01-01

    Background: The U.S. health care system has been under immense scrutiny for ever-increasing costs and poor health outcomes for its patients. Comparative Effectiveness Research (CER) has emerged as a generally accepted practice by providers, policy makers, and scientists as an approach to identify the most clinical- and cost-effective interventions…

  18. Trabecular bone structure analysis in the osteoporotic spine using a clinical in vivo setup for 64-slice MDCT imaging: comparison to microCT imaging and microFE modeling.

    PubMed

    Issever, Ahi S; Link, Thomas M; Kentenich, Marie; Rogalla, Patrik; Schwieger, Karsten; Huber, Markus B; Burghardt, Andrew J; Majumdar, Sharmila; Diederichs, Gerd

    2009-09-01

    Assessment of trabecular microarchitecture may improve estimation of biomechanical strength, but visualization of trabecular bone structure in vivo is challenging. We tested the feasibility of assessing trabecular microarchitecture in the spine using multidetector CT (MDCT) on intact human cadavers in an experimental in vivo-like setup. BMD, bone structure (e.g., bone volume/total volume = BV/TV; trabecular thickness = Tb.Th; structure model index = SMI) and bone texture parameters were evaluated in 45 lumbar vertebral bodies using MDCT (mean in-plane pixel size, 274 microm(2); slice thickness, 500 microm). These measures were correlated with structure measures assessed with microCT at an isotropic spatial resolution of 16 microm and to microfinite element models (microFE) of apparent modulus and stiffness. MDCT-derived BMD and structure measures showed significant correlations to the density and structure obtained by microCT (BMD, R(2) = 0.86, p < 0.0001; BV/TV, R(2) = 0.64, p < 0.0001; Tb.Th, R(2) = 0.36, p < 0.01). When comparing microCT-derived measures with microFE models, the following correlations (p < 0.001) were found for apparent modulus and stiffness, respectively: BMD (R(2) = 0.58 and 0.66), BV/TV (R(2) = 0.44 and 0.58), and SMI (R(2) = 0.44 and 0.49). However, the overall highest correlation (p < 0.001) with microFE app. modulus (R(2) = 0.75) and stiffness (R(2) = 0.76) was achieved by the combination of QCT-derived BMD with the bone texture measure Minkowski Dimension. In summary, although still limited by its spatial resolution, trabecular bone structure assessment using MDCT is overall feasible. However, when comparing with microFE-derived bone properties, BMD is superior compared with single parameters for microarchitecture, and correlations further improve when combining with texture measures.

  19. Spectrum of MDCT Findings in Bowel Obstruction in a Tertiary Care Rural Hospital in Northern India

    PubMed Central

    Gupta, Ranjana; Mittal, Amit; Gupta, Sharad; Mittal, Kapish; Taneja, Arpit

    2016-01-01

    Introduction Multidetector Computed Tomography (MDCT) provides clinically and surgically important information in bowel obstruction. It can depict the severity, level and cause of obstruction. Aim To depict the spectrum of MDCT findings in cases of small and large bowel obstruction. Materials and Methods Contrast enhanced MDCT examination of 50 patients were retrospectively included in the study who had evidence of clinical as well as MDCT evidence of bowel obstruction and in whom surgical/clinical follow-up for final diagnosis was available. CT scan was done in all the patients with Ingenuity CT (128 slice MDCT, Philips Medical Systems). The axial sections were reconstructed in coronal and sagital planes to determine site and cause of bowel obstruction. Results There were 34 males and 16 females patients in this study with mean age of 28.4 years. The level of obstruction was in small bowel in 39 patients (76.67%) and large bowel in 11 patients (23.33%). Adhesive bands were the cause of Small Bowel Obstruction (SBO) in 17 patients (43.5% of SBO patients). The most common CT signs in adhesive band SBO were beak sign (seen in 70.6% patients) and fat notch sign (52.9% patients). Five cases of SBO were secondary to benign stricture. Matted adhesions were the cause of obstruction in 3 patients. All these patients showed transition zone in pelvis with positive small bowel faeces sign. Two patients with SBO due to adhesive band had evidence of closed loop obstruction with evidence of gangrenous gut on surgery. Large Bowel Obstruction (LBO) was seen in 11 patients. Most common cause of LBO was primary colonic malignancy, accounting for 7 patients (63.6%). In one patient, the cause was direct invasion of hepatic flexure by carcinoma of gall bladder. Other causes of LBO were pelvic adhesions, faecal impaction and ischaemic stricture. Conclusion SBO is more common than LBO with adhesive bands being the most common cause of SBO. MDCT is very useful for depicting site and cause

  20. Comparative energetics of the observed and simulated global circulation during the special observing periods of FGGE

    NASA Technical Reports Server (NTRS)

    Kung, E. C.; Baker, W. E.

    1986-01-01

    Energetics of the observed and simulated global circulation are evaluated in the zonal spectral domain for the special observing periods of FGGE. The study utilizes GLA analyses of FGGE observational data and parallel simulation experiments. There are noticeable differences in energy transformations between the observation and simulation during SOP-1. These include the baroclinic conversion C(n) by the zonal mean motion and short-wave disturbances, and the nonlinear wave-wave interaction L(n) at the long and short waves. The energy transformations of the short-wave disturbances are much more intense in the simulated circulation than in the observation. However, good agreement is noted in the conversion and dissipation of kinetic energy in the large- and cyclone-wave range n = 1-10. Spectral distributions of global energy transformations at the long- and cyclone-wave range indicate that the SOP-2 simulation agrees more closely with the observed fields than the SOP-1 simulation. Other pertinent points of energetics diagnosis are also included in the discussion.

  1. Ectopia cordis with tetralogy of Fallot in an infant with pentalogy of Cantrell: high-pitch MDCT exam.

    PubMed

    Santiago-Herrera, Rogerio; Ramirez-Carmona, Rocio; Criales-Vera, Sergio; Calderon-Colmenero, Juan; Kimura-Hayama, Eric

    2011-07-01

    We report the MDCT findings of a 17-month-old girl with Cantrell's pentalogy, a rare congenital disease characterized by several defects in the ventral thoracoabdominal wall including ectopia cordis, and, in this patient, associated with tetralogy of Fallot. This case provides an example of the utility of a wide volume in coverage and high-pitch MDCT scan in the evaluation of complex cardiovascular anatomy in infants with congenital heart disease without the need of an ECG-gating acquisition.

  2. Congenital thoracic vascular anomalies: evaluation with state-of-the-art MR imaging and MDCT.

    PubMed

    Hellinger, Jeffrey C; Daubert, Melissa; Lee, Edward Y; Epelman, Monica

    2011-09-01

    Congenital thoracic vascular anomalies include embryologic developmental disorders of the thoracic aorta, aortic arch branch arteries, pulmonary arteries, thoracic systemic veins, and pulmonary veins. Diagnostic evaluation of these anomalies in pediatric patients has evolved with innovations in diagnostic imaging technology. State-of-the-art magnetic resonance (MR) imaging, MR angiography multidetector-row computed tomographic (MDCT) angiography, and advanced postprocessing visualization techniques offer accurate and reliable high-resolution two-dimensional and three-dimensional noninvasive anatomic displays for interpretation and clinical management of congenital thoracic vascular anomalies. This article reviews vascular MR imaging, MR angiography, MDCT angiography, and advanced visualization techniques and applications for the assessment of congenital thoracic vascular anomalies, emphasizing clinical embryology and the characteristic imaging findings.

  3. State-of-the-art preoperative staging of gastric cancer by MDCT and magnetic resonance imaging

    PubMed Central

    Choi, Joon-Il; Joo, Ijin; Lee, Jeong Min

    2014-01-01

    Gastric cancer is one of the most common and fatal cancers. The importance of accurate staging for gastric cancer has become more critical due to the recent introduction of less invasive treatment options, such as endoscopic mucosal resection or laparoscopic surgery. The tumor-node-metastasis staging system is the generally accepted staging system for predicting the prognosis of patients with gastric cancer. Multidetector row computed tomography (MDCT) is a widely accepted imaging modality for the preoperative staging of gastric cancer that can simultaneously assess locoregional staging, including the gastric mass, regional lymph nodes, and distant metastasis. The diagnostic performance of MDCT for T- and N-staging has been improved by the technical development of isotropic imaging and 3D reformation. Although magnetic resonance imaging (MRI) was not previously used to evaluate gastric cancer due to the modality’s limitations, the development of high-speed sequences has made MRI a feasible tool for the staging of gastric cancer. PMID:24782607

  4. MDCT Imaging Findings of Liver Cirrhosis: Spectrum of Hepatic and Extrahepatic Abdominal Complications

    PubMed Central

    Sangster, Guillermo P.; Previgliano, Carlos H.; Nader, Mathieu; Chwoschtschinsky, Elisa; Heldmann, Maureen G.

    2013-01-01

    Hepatic cirrhosis is the clinical and pathologic result of a multifactorial chronic liver injury. It is well known that cirrhosis is the origin of multiple extrahepatic abdominal complications and a markedly increased risk of hepatocellular carcinoma (HCC). This tumor is the sixth most common malignancy worldwide and the third most common cause of cancer related death. With the rising incidence of HCC worldwide, awareness of the evolution of cirrhotic nodules into malignancy is critical for an early detection and treatment. Adequate imaging protocol selection with dynamic multiphase Multidetector Computed Tomography (MDCT) and reformatted images is crucial to differentiate and categorize the hepatic nodular dysplasia. Knowledge of the typical and less common extrahepatic abdominal manifestations is essential for accurately assessing patients with known or suspected hepatic disease. The objective of this paper is to illustrate the imaging spectrum of intra- and extrahepatic abdominal manifestations of hepatic cirrhosis seen on MDCT. PMID:23986608

  5. Robust method for extracting the pulmonary vascular trees from 3D MDCT images

    NASA Astrophysics Data System (ADS)

    Taeprasartsit, Pinyo; Higgins, William E.

    2011-03-01

    Segmentation of pulmonary blood vessels from three-dimensional (3D) multi-detector CT (MDCT) images is important for pulmonary applications. This work presents a method for extracting the vascular trees of the pulmonary arteries and veins, applicable to both contrast-enhanced and unenhanced 3D MDCT image data. The method finds 2D elliptical cross-sections and evaluates agreement of these cross-sections in consecutive slices to find likely cross-sections. It next employs morphological multiscale analysis to separate vessels from adjoining airway walls. The method then tracks the center of the likely cross-sections to connect them to the pulmonary vessels in the mediastinum and forms connected vascular trees spanning both lungs. A ground-truth study indicates that the method was able to detect on the order of 98% of the vessel branches having diameter >= 3.0 mm. The extracted vascular trees can be utilized for the guidance of safe bronchoscopic biopsy.

  6. Does Computed Tomography Change our Observation and Management of Fracture Non-Unions?

    PubMed Central

    Kleinlugtenbelt, Ydo V.; Scholtes, Vanessa A.B.; Toor, Jay; Amaechi, Christian; Maas, Mario; Bhandari, Mohit; Poolman, Rudolf W.; Kloen, Peter

    2016-01-01

    Background: The purpose of this study was to determine whether Multi-Detector Computed Tomography (MDCT) in addition to plain radiographs influences radiologists’ and orthopedic surgeons’ diagnosis and treatment plans for delayed unions and non-unions. Methods: A retrospective database of 32 non-unions was reviewed by 20 observers. On a scale of 1 to 5, observers rated on X-Ray and a subsequent Multi Detector Helical Computer Tomography (MDCT) scan was performed to determine the following categories: “healed”, “bridging callus present”, “persistent fracture line” or “surgery advised”. Interobserver reliability in each category was calculated using the Interclass Correlation Coefficient (ICC). The influence of the MDCT scan on the raters’ observations was determined in each case by subtracting the two scores of both time points. Results: All four categories show fair interobserver reliability when using plain radiographs. MDCT showed no improvement, the reliability was poor for the categories “bridging callus present” and “persistent fracture line”, and fair for “healed” and “surgery advised”. In none of the cases, MDCT led to a change of management from nonoperative to operative treatment or vice versa. For 18 out of 32 cases, the treatment plans did not alter. In seven cases MDCT led to operative treatment while on X-ray the treatment plan was undecided. Conclusion: In this study, the interobserver reliability of MDCT scan is not greater than conventional radiographs for determining non-union. However, a MDCT scan did lead to a more invasive approach in equivocal cases. Therefore a MDCT is only recommended for making treatment strategies in those cases. PMID:27847846

  7. Spectrum of imaging findings on MDCT enterography in patients with small bowel tuberculosis.

    PubMed

    Kalra, N; Agrawal, P; Mittal, V; Kochhar, R; Gupta, V; Nada, R; Singh, R; Khandelwal, N

    2014-03-01

    Abdominal tuberculosis (TB) is the sixth most common extrapulmonary site of involvement. The sites of involvement in abdominal tuberculosis, in descending order of frequency, are lymph nodes, genitourinary tract, peritoneal cavity, and gastrointestinal tract. The radiological armamentarium for evaluating tuberculosis of the small bowel (SBTB) includes barium studies (small bowel follow-through, SBFT), CT (multidetector CT, CT enterography, and CT enteroclysis), ultrasound (sonoenteroclysis), and magnetic resonance imaging (MRI; enterography and enteroclysis). In this review, we illustrate the abnormalities at MDCT enterography in 20 consecutive patients with SB TB and also describe extraluminal findings in these patients. MDCT enterography allows non-invasive good-quality assessment of well-distended bowel loops and the adjacent soft tissues. It displays the thickness and enhancement of the entire bowel wall in all three planes and allows examination of all bowel loops, especially the ileal loops, which are mostly superimposed. The terminal ileum and ileocaecal junction are the most common sites of small bowel involvement in intestinal TB. The most common abnormality is short-segment strictures with symmetrical concentric mural thickening and homogeneous mural enhancement. Other findings include lymphadenopathy, ascites, enteroliths, peritoneal thickening, and enhancement. In conclusion, MDCT enterography is a comprehensive technique for the evaluation of SB TB.

  8. The development, validation and application of a multi-detector CT (MDCT) scanner model for assessing organ doses to the pregnant patient and the fetus using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Gu, J.; Bednarz, B.; Caracappa, P. F.; Xu, X. G.

    2009-05-01

    The latest multiple-detector technologies have further increased the popularity of x-ray CT as a diagnostic imaging modality. There is a continuing need to assess the potential radiation risk associated with such rapidly evolving multi-detector CT (MDCT) modalities and scanning protocols. This need can be met by the use of CT source models that are integrated with patient computational phantoms for organ dose calculations. Based on this purpose, this work developed and validated an MDCT scanner using the Monte Carlo method, and meanwhile the pregnant patient phantoms were integrated into the MDCT scanner model for assessment of the dose to the fetus as well as doses to the organs or tissues of the pregnant patient phantom. A Monte Carlo code, MCNPX, was used to simulate the x-ray source including the energy spectrum, filter and scan trajectory. Detailed CT scanner components were specified using an iterative trial-and-error procedure for a GE LightSpeed CT scanner. The scanner model was validated by comparing simulated results against measured CTDI values and dose profiles reported in the literature. The source movement along the helical trajectory was simulated using the pitch of 0.9375 and 1.375, respectively. The validated scanner model was then integrated with phantoms of a pregnant patient in three different gestational periods to calculate organ doses. It was found that the dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. The paper also discusses how these fetal dose values can be used to evaluate imaging procedures and to assess risk using recommendations of the report from AAPM Task Group 36. This work demonstrates the ability of modeling and validating an MDCT scanner by the Monte Carlo method, as well as

  9. The development, validation and application of a multi-detector CT (MDCT) scanner model for assessing organ doses to the pregnant patient and the fetus using Monte Carlo simulations.

    PubMed

    Gu, J; Bednarz, B; Caracappa, P F; Xu, X G

    2009-05-07

    The latest multiple-detector technologies have further increased the popularity of x-ray CT as a diagnostic imaging modality. There is a continuing need to assess the potential radiation risk associated with such rapidly evolving multi-detector CT (MDCT) modalities and scanning protocols. This need can be met by the use of CT source models that are integrated with patient computational phantoms for organ dose calculations. Based on this purpose, this work developed and validated an MDCT scanner using the Monte Carlo method, and meanwhile the pregnant patient phantoms were integrated into the MDCT scanner model for assessment of the dose to the fetus as well as doses to the organs or tissues of the pregnant patient phantom. A Monte Carlo code, MCNPX, was used to simulate the x-ray source including the energy spectrum, filter and scan trajectory. Detailed CT scanner components were specified using an iterative trial-and-error procedure for a GE LightSpeed CT scanner. The scanner model was validated by comparing simulated results against measured CTDI values and dose profiles reported in the literature. The source movement along the helical trajectory was simulated using the pitch of 0.9375 and 1.375, respectively. The validated scanner model was then integrated with phantoms of a pregnant patient in three different gestational periods to calculate organ doses. It was found that the dose to the fetus of the 3 month pregnant patient phantom was 0.13 mGy/100 mAs and 0.57 mGy/100 mAs from the chest and kidney scan, respectively. For the chest scan of the 6 month patient phantom and the 9 month patient phantom, the fetal doses were 0.21 mGy/100 mAs and 0.26 mGy/100 mAs, respectively. The paper also discusses how these fetal dose values can be used to evaluate imaging procedures and to assess risk using recommendations of the report from AAPM Task Group 36. This work demonstrates the ability of modeling and validating an MDCT scanner by the Monte Carlo method, as well as

  10. Coronary fly-through or virtual angioscopy using dual-source MDCT data.

    PubMed

    van Ooijen, Peter M A; de Jonge, Gonda; Oudkerk, Matthijs

    2007-11-01

    Coronary fly-through or virtual angioscopy (VA) has been studied ever since its invention in 2000. However, application was limited because it requires an optimal computed tomography (CT) scan and time-consuming post-processing. Recent advances in post-processing software facilitate easy construction of VA, but until now image quality was insufficient in most patients. The introduction of dual-source multidetector CT (MDCT) could enable VA in all patients. Twenty patients were scanned using a dual-source MDCT (Definition, Siemens, Forchheim, Germany) using a standard coronary artery protocol. Post-processing was performed on an Aquarius Workstation (TeraRecon, San Mateo, Calif.). Length travelled per major branch was recorded in millimetres, together with the time required in minutes. VA could be performed in every patient for each of the major coronary arteries. The mean (range) length of the automated fly-through was 80 (32-107) mm for the left anterior descending (LAD), 75 (21-116) mm for the left circumflex artery (LCx), and 109 (21-190) mm for the right coronary artery (RCA). Calcifications and stenoses were visualised, as well as most side branches. The mean time required was 3 min for LAD, 2.5 min for LCx, and 2 min for the RCA. Dual-source MDCT allows for high quality visualisation of the coronary arteries in every patient because scanning with this machine is independent of the heart rate. This is clearly shown by the successful VA in all patients. Potential clinical value of VA should be determined in the near future.

  11. Live versus Video Observations: Comparing the Reliability and Validity of Two Methods of Assessing Classroom Quality

    ERIC Educational Resources Information Center

    Curby, Timothy W.; Johnson, Price; Mashburn, Andrew J.; Carlis, Lydia

    2016-01-01

    When conducting classroom observations, researchers are often confronted with the decision of whether to conduct observations live or by using pre-recorded video. The present study focuses on comparing and contrasting observations of live and video administrations of the Classroom Assessment Scoring System-PreK (CLASS-PreK). Associations between…

  12. Ileocaecal Intussusception with a Lead Point: Unusual MDCT Findings of Active Crohn's Disease Involving the Appendix

    PubMed Central

    Ozan, Ebru; Atac, Gokce Kaan; Akincioglu, Egemen; Keskin, Mete; Gulpinar, Kamil

    2015-01-01

    Adult intussusception is a rare entity accounting for 1% of all bowel obstructions. Unlike intussusceptions in children, which are idiopathic in 90% of cases, adult intussusceptions have an identifiable cause (lead point) in the majority of cases. Crohn's disease (CD) may affect any part of the gastrointestinal tract, including the appendix. It was shown to be a predisposing factor for intussusception. Here, we report a rare case of adult intussusception with a lead point, emphasizing diagnostic input of multidetector computed tomography (MDCT) in a patient with active CD that involves the appendix. PMID:26558130

  13. Esophagobronchial fistulae: Diagnosis by MDCT with oral contrast swallow examination of a benign and a malignant cause

    PubMed Central

    Hegde, Rahul G; Kalekar, Tushar M; Gajbhiye, Meenakshi I; Bandgar, Amol S; Pawar, Shephali S; Khadse, Gopal J

    2013-01-01

    We report two cases of esophagobronchial fistulae diagnosed by Multi-detector computed tomography (MDCT) oral contrast swallow examination. It is helpful to supplement the CT study with an oral contrast swallow as it aids in confirmation of a suspected fistula and also demonstrates the fistula tract better. We present the clinical details and the imaging findings on MDCT of two cases of esophagobronchial fistulae – one secondary to chronic chest tuberculosis and the other secondary to a squamous cell carcinoma of the upper esophagus – followed by discussion of the etiology, pathogenesis, and imaging of these fistulae. PMID:24082484

  14. Whole-Chest 64-MDCT of Emergency Department Patients with Nonspecific Chest Pain: Radiation Dose and Coronary Artery Image Quality with Prospective ECG Triggering Versus Retrospective ECG Gating

    PubMed Central

    Shuman, William P.; Branch, Kelley R.; May, Janet M.; Mitsumori, Lee M.; Strote, Jared N.; Warren, Bill H.; Dubinsky, Theodore J.; Lockhart, David W.; Caldwell, James H.

    2012-01-01

    Objective The purpose of this study was to compare the patient radiation dose and coronary artery image quality of long-z-axis whole-chest 64-MDCT performed with retrospective ECG gating with those of CT performed with prospective ECG triggering in the evaluation of emergency department patients with nonspecific chest pain. Subjects and Methods Consecutively registered emergency department patients with nonspecific low-to-moderate-risk chest pain underwent whole-chest CT with retrospective gating (n = 41) or prospective triggering (n = 31). Effective patient radiation doses were estimated and compared by use of unpaired Student's t tests. Two reviewers independently scored the quality of images of the coronary arteries, and the scores were compared by use of ordinal logistic regression. Results Age, heart rate, body mass index, and z-axis coverage were not statistically different between the two groups. For retrospective gating, the mean effective radiation dose was 31.8 ± 5.1 mSv; for prospective triggering, the mean effective radiation dose was 9.2 ± 2.2 mSv (prospective triggering 71% lower, p < 0.001). Two of 512 segments imaged with retrospective gating were nonevaluable (0.4%), and two of 394 segments imaged with prospective triggering were nonevaluable (0.5%). Prospectively triggered images were 2.2 (95% CI, 1.1–4.5) times as likely as retrospectively gated images to receive a high image quality score for each segment after adjustment for segment differences (p < 0.05). Conclusion For long-z-axis whole-chest 64-MDCT of emergency department patients with nonspecific chest pain, use of prospective ECG triggering may result in substantially lower patient radiation doses and better coronary artery image quality than is achieved with retrospective ECG gating. PMID:19457832

  15. Radiofrequency Ablation of Liver Metastases-Software-Assisted Evaluation of the Ablation Zone in MDCT: Tumor-Free Follow-Up Versus Local Recurrent Disease

    SciTech Connect

    Keil, Sebastian Bruners, Philipp; Schiffl, Katharina; Sedlmair, Martin; Muehlenbruch, Georg; Guenther, Rolf W.; Das, Marco; Mahnken, Andreas H.

    2010-04-15

    The purpose of this study was to investigate differences in change of size and CT value between local recurrences and tumor-free areas after CT-guided radiofrequency ablation (RFA) of hepatic metastases during follow-up by means of dedicated software for automatic evaluation of hepatic lesions. Thirty-two patients with 54 liver metastases from breast or colorectal cancer underwent triphasic contrast-enhanced multidetector-row computed tomography (MDCT) to evaluate hepatic metastatic spread and localization before CT-guided RFA and for follow-up after intervention. Sixteen of these patients (65.1 {+-} 10.3 years) with 30 metastases stayed tumor-free (group 1), while the other group (n = 16 with 24 metastases; 62.0 {+-} 13.8 years) suffered from local recurrent disease (group 2). Applying an automated software tool (SyngoCT Oncology; Siemens Healthcare, Forchheim, Germany), size parameters (volume, RECIST, WHO) and attenuation were measured within the lesions before, 1 day after, and 28 days after RFA treatment. The natural logarithm (ln) of the quotient of the volume 1 day versus 28 days after RFA treament was computed: lnQ1//28/0{sub volume}. Analogously, ln ratios of RECIST, WHO, and attenuation were computed and statistically evaluated by repeated-measures ANOVA. One lesion in group 2 was excluded from further evaluation due to automated missegmentation. Statistically significant differences between the two groups were observed with respect to initial volume, RECIST, and WHO (p < 0.05). Furthermore, ln ratios corresponding to volume, RECIST, and WHO differed significantly between the two groups. Attenuation evaluations showed no significant differences, but there was a trend toward attenuation assessment for the parameter lnQ28/0{sub attenuation} (p = 0.0527), showing higher values for group 1 (-0.4 {+-} 0.3) compared to group 2 (-0.2 {+-} 0.2). In conclusion, hepatic metastases and their zone of coagulation necrosis after RFA differed significantly between tumor

  16. Radiofrequency ablation of liver metastases-software-assisted evaluation of the ablation zone in MDCT: tumor-free follow-up versus local recurrent disease.

    PubMed

    Keil, Sebastian; Bruners, Philipp; Schiffl, Katharina; Sedlmair, Martin; Mühlenbruch, Georg; Günther, Rolf W; Das, Marco; Mahnken, Andreas H

    2010-04-01

    The purpose of this study was to investigate differences in change of size and CT value between local recurrences and tumor-free areas after CT-guided radiofrequency ablation (RFA) of hepatic metastases during follow-up by means of dedicated software for automatic evaluation of hepatic lesions. Thirty-two patients with 54 liver metastases from breast or colorectal cancer underwent triphasic contrast-enhanced multidetector-row computed tomography (MDCT) to evaluate hepatic metastatic spread and localization before CT-guided RFA and for follow-up after intervention. Sixteen of these patients (65.1 + or - 10.3 years) with 30 metastases stayed tumor-free (group 1), while the other group (n = 16 with 24 metastases; 62.0 + or - 13.8 years) suffered from local recurrent disease (group 2). Applying an automated software tool (SyngoCT Oncology; Siemens Healthcare, Forchheim, Germany), size parameters (volume, RECIST, WHO) and attenuation were measured within the lesions before, 1 day after, and 28 days after RFA treatment. The natural logarithm (ln) of the quotient of the volume 1 day versus 28 days after RFA treament was computed: lnQ1//28/0(volume). Analogously, ln ratios of RECIST, WHO, and attenuation were computed and statistically evaluated by repeated-measures ANOVA. One lesion in group 2 was excluded from further evaluation due to automated missegmentation. Statistically significant differences between the two groups were observed with respect to initial volume, RECIST, and WHO (p < 0.05). Furthermore, ln ratios corresponding to volume, RECIST, and WHO differed significantly between the two groups. Attenuation evaluations showed no significant differences, but there was a trend toward attenuation assessment for the parameter lnQ28/0(attenuation) (p = 0.0527), showing higher values for group 1 (-0.4 + or - 0.3) compared to group 2 (-0.2 + or - 0.2). In conclusion, hepatic metastases and their zone of coagulation necrosis after RFA differed significantly between tumor

  17. Comparison of hepatic MDCT, MRI, and DSA to explant pathology for the detection and treatment planning of hepatocellular carcinoma

    PubMed Central

    Ladd, Lauren M.; Tirkes, Temel; Tann, Mark; Agarwal, David M.; Johnson, Matthew S.; Tahir, Bilal; Sandrasegaran, Kumaresan

    2016-01-01

    Background/Aims The diagnosis and treatment plan for hepatocellular carcinoma (HCC) can be made from radiologic imaging. However, lesion detection may vary depending on the imaging modality. This study aims to evaluate the sensitivities of hepatic multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA) in the detection of HCC and the consequent management impact on potential liver transplant patients. Methods One hundred and sixteen HCC lesions were analyzed in 41 patients who received an orthotopic liver transplant (OLT). All of the patients underwent pretransplantation hepatic DSA, MDCT, and/or MRI. The imaging results were independently reviewed retrospectively in a blinded fashion by two interventional and two abdominal radiologists. The liver explant pathology was used as the gold standard for assessing each imaging modality. Results The sensitivity for overall HCC detection was higher for cross-sectional imaging using MRI (51.5%, 95% confidence interval [CI]=36.2-58.4%) and MDCT (49.8%, 95% CI=43.7-55.9%) than for DSA (41.7%, 95% CI=36.2-47.3%) (P=0.05). The difference in false-positive rate was not statistically significant between MRI (22%), MDCT (29%), and DSA (29%) (P=0.67). The sensitivity was significantly higher for detecting right lobe lesions than left lobe lesions for all modalities (MRI: 56.1% vs. 43.1%, MDCT: 55.0% vs. 42.0%, and DSA: 46.9% vs. 33.9%; all P<0.01). The sensitivities of the three imaging modalities were also higher for lesions ≥2 cm vs. <2 cm (MRI: 73.4% vs. 32.7%, MDCT: 66.9% vs. 33.8%, and DSA: 62.2% vs. 24.1%; all P<0.01). The interobserver correlation was rated as very good to excellent. Conclusion The sensitivity for detecting HCC is higher for MRI and MDCT than for DSA, and so cross-sectional imaging modalities should be used to evaluate OLT candidacy. PMID:27987537

  18. Solar irradiance computations compared with observations at the Baseline Surface Radiation Network Payerne site

    SciTech Connect

    Nowak, Daniela; Vuilleumier, Laurent; Long, Charles N.; Ohmura, Atsumu

    2008-07-18

    Radiative transfer model calculations of solar fluxes during cloud free periods often show considerable discrepancies with surface radiation observations. Many efforts have been undertaken to explain the differences between modeled and observed shortwave downward radiation (SDR). In this study, MODTRAN4v3r1TM (designed later simply as MODTRANTM) was used for model simulations and compared with high quality radiation observations of the Baseline Surface Radiation Network (BSRN) site at Payerne, Switzerland. Results are presented for cloud free shortwave downward radiation calculations. The median differences of modeled minus observed global SDR are small (< 1%) and within the instrumental error. The differences of modeled and observed direct and diffuse SDR show larger discrepancies of -1.8% and 5.2% respectively. The diffuse SDR is generally overestimated by the model and more important, the model to observation linear regression slope and zero-intercept differs significantly from their ideal values of 1 and 0. Possible reasons for the discrepancies are presented and discussed and some modifications are investigated for decreasing such differences between modeled and observed diffuse SDR. However, we could not resolve all the discrepancies. The best agreement is obtained when comparing model simulations whose 550nm aerosol optical depth input is inferred from observations using nine spectral channels, and using BSRN observations performed with a new and more precise shading disk and sun tracker system. In this case, the median bias between model simulations and observed diffuse SDR is -0.4 Wm-2 (< 1%).

  19. Comparing GOSAT observations of localized CO2 enhancements by large emitters with inventory-based estimates

    NASA Astrophysics Data System (ADS)

    Janardanan, Rajesh; Maksyutov, Shamil; Oda, Tomohiro; Saito, Makoto; Kaiser, Johannes W.; Ganshin, Alexander; Stohl, Andreas; Matsunaga, Tsuneo; Yoshida, Yukio; Yokota, Tatsuya

    2016-04-01

    We employed an atmospheric transport model to attribute column-averaged CO2 mixing ratios (XCO2) observed by Greenhouse gases Observing SATellite (GOSAT) to emissions due to large sources such as megacities and power plants. XCO2 enhancements estimated from observations were compared to model simulations implemented at the spatial resolution of the satellite observation footprint (0.1° × 0.1°). We found that the simulated XCO2 enhancements agree with the observed over several continental regions across the globe, for example, for North America with an observation to simulation ratio of 1.05 ± 0.38 (p < 0.1), but with a larger ratio over East Asia (1.22 ± 0.32; p < 0.05). The obtained observation-model discrepancy (22%) for East Asia is comparable to the uncertainties in Chinese emission inventories (~15%) suggested by recent reports. Our results suggest that by increasing the number of observations around emission sources, satellite instruments like GOSAT can provide a tool for detecting biases in reported emission inventories.

  20. Comparing GOSAT Observations of Localized CO2 Enhancements by Large Emitters with Inventory-Based Estimates

    NASA Technical Reports Server (NTRS)

    Janardanan, Rajesh; Maksyutov, Shamil; Oda, Tomohiro; Saito, Makoto; Kaiser, Johannes W.; Ganshin, Alexander; Stohl, Andreas; Matsunaga, Tsuneo; Yoshida, Yukio; Yokota, Tatsuya

    2016-01-01

    We employed an atmospheric transport model to attribute column-averaged CO2 mixing ratios (XCO2) observed by Greenhouse gases Observing SATellite (GOSAT) to emissions due to large sources such as megacities and power plants. XCO2 enhancements estimated from observations were compared to model simulations implemented at the spatial resolution of the satellite observation footprint (0.1deg × 0.1deg). We found that the simulated XCO2 enhancements agree with the observed over several continental regions across the globe, for example, for North America with an observation to simulation ratio of 1.05 +/- 0.38 (p<0.1), but with a larger ratio over East Asia (1.22 +/- 0.32; p<0.05). The obtained observation-model discrepancy (22%) for East Asia is comparable to the uncertainties in Chinese emission inventories (approx.15%) suggested by recent reports. Our results suggest that by increasing the number of observations around emission sources, satellite instruments like GOSAT can provide a tool for detecting biases in reported emission inventories.

  1. A Rare Presentation of an Entrapment in a Liver Transplant Candidate Depicted by MDCT Angiography

    PubMed Central

    Kantarci, Mecit; Aydin, Unal; Doganay, Selim; Aydinli, Bulent; Yuce, Ihsan; Polat, Kamil Yalcin

    2010-01-01

    Hypertrophic caudate lobe veins can mimic a normal venous configuration. In cases of multiple vascular collaterals, Doppler evaluations must be conducted, and the flow direction of these veins as well as the IVC should be evaluated. If the flow in the IVC is reversed, Budd-Chiari syndrome should be suspected; moreover, at the supra diaphragmatic level, which may be considered a blind spot, particularly for radiologists, a web should be searched for in the area where the IVC opens into the right atrium. In this study, we present the unique findings of multidetector computed tomography (MDCT) angiography for a liver transplant candidate with Budd-Chiari syndrome caused by a web in the proximal IVC. PMID:25610132

  2. Diagnostic Value and Interreader Agreement of the Pancreaticolienal Gap in Pancreatic Cancer on MDCT

    PubMed Central

    Schawkat, Khoschy; Kühn, Wolfgang; Inderbitzin, Daniel; Gloor, Beat; Heverhagen, Johannes T.; Runge, Val Murray; Christe, Andreas

    2016-01-01

    Objective The aim of this retrospective study was to evaluate the diagnostic value and measure interreader agreement of the pancreaticolienal gap (PLG) in the assessment of imaging features of pancreatic carcinoma (PC) on contrast-enhanced multi-detector computed tomography (CE-MDCT). Materials and Methods CE-MDCT studies in the portal venous phase were retrospectively reviewed for 66 patients with PC. The age- and gender-matched control group comprised 103 healthy individuals. Three radiologists with different levels of experience independently measured the PLG (the minimum distance of the pancreatic tail to the nearest border of the spleen) in the axial plane. The interreader agreement of the PLG and the receiver operating characteristic (ROC) curve was used to calculate the accuracy of the technique. Results While the control group (n = 103) showed a median PLG of 3 mm (Range: 0 – 39mm) the PC patients had a significantly larger PLG of 15mm (Range: 0 – 53mm)(p < 0.0001). A ROC curve demonstrated a cutoff-value of >12 mm for PC, with a sensitivity of 58.2% (95% CI = 45.5–70.1), specificity of 84.0% (95% CI = 75.6–90.4) and an area under the ROC curve of 0.714 (95% CI = 0.641 to 0.780). The mean interreader agreement showed correlation coefficient r of 0.9159. The extent of the PLG did not correlate with tumor stage but did correlate with pancreatic density (fatty involution) and age, the density decreased by 4.1 HU and the PLG increased by 0.8 mm within every 10 y. Conclusion The significant interreader agreement supports the use of the PLG as a characterizing feature of pancreatic cancer independent of the tumor stage on an axial plane. The increase in the PLG with age may represent physiological atrophy of the pancreatic tail. PMID:27893776

  3. On the Law of Comparative Judgment: Scaling with Intransitive Observers and Multidimensional Stimuli.

    ERIC Educational Resources Information Center

    Hull, R. Bruce, IV; Buhyoff, Gregory J.

    1981-01-01

    Intransitives in observers' preference judgements for multidimensional natural landscape scenes are examined. Thurstone's Law of Comparative Judgement (LCJ) psychophysical scaling routine is used to scale landscape preference. Both the method of Rank Ordering (RO) and the method of Paired Comparisons (PC) are used to gather the raw data necessary…

  4. Helping Teenagers Stop Smoking: Comparative Observations across Youth Settings in Cardiff

    ERIC Educational Resources Information Center

    Bowles, Hannah; Maher, Alison; Sage, Robert

    2009-01-01

    Objective: This paper presents comparative observations between schools/colleges, youth centres, and specialist youth provision, in relation to delivery of the 2tuff2puff six-week smoking cessation and awareness programme to young people in Cardiff. Design: A six-week smoking cessation programme was delivered to 12-23 year olds in various youth…

  5. Assessing Observer Accuracy in Continuous Recording of Rate and Duration: Three Algorithms Compared

    ERIC Educational Resources Information Center

    Mudford, Oliver C.; Martin, Neil T.; Hui, Jasmine K. Y.; Taylor, Sarah Ann

    2009-01-01

    The three algorithms most frequently selected by behavior-analytic researchers to compute interobserver agreement with continuous recording were used to assess the accuracy of data recorded from video samples on handheld computers by 12 observers. Rate and duration of responding were recorded for three samples each. Data files were compared with…

  6. Diagnostics comparing sea surface temperature feedbacks from operational hurricane forecasts to observations

    NASA Astrophysics Data System (ADS)

    Lloyd, Ian D.; Marchok, Timothy; Vecchi, Gabriel A.

    2011-04-01

    This paper examines the ability of recent versions of the Geophysical Fluid Dynamics Laboratory Operational Hurricane Forecast Model (GHM) to reproduce the observed relationship between hurricane intensity and hurricane-induced Sea Surface Temperature (SST) cooling. The analysis was performed by taking a Lagrangian composite of all hurricanes in the North Atlantic from 1998-2009 in observations and 2005-2009 for the GHM. A marked improvement in the intensity-SST relationship for the GHM compared to observations was found between the years 2005 and 2006-2009 due to the introduction of warm-core eddies, a representation of the loop current, and changes to the drag coefficient parameterization for bulk turbulent flux computation. A Conceptual Hurricane Intensity Model illustrates the essential steady-state characteristics of the intensity-SST relationship and is explained by two coupled equations for the atmosphere and ocean. The conceptual model qualitatively matches observations and the 2006-2009 period in the GHM, and presents supporting evidence for the conclusion that weaker upper oceanic thermal stratification in the Gulf of Mexico, caused by the introduction of the loop current and warm core eddies, is crucial to explaining the observed SST-intensity pattern. The diagnostics proposed by the conceptual model offer an independent set of metrics for comparing operational hurricane forecast models to observations.

  7. Comparing the Scoring of Human Decomposition from Digital Images to Scoring Using On-site Observations.

    PubMed

    Dabbs, Gretchen R; Bytheway, Joan A; Connor, Melissa

    2017-01-25

    When in forensic casework or empirical research in-person assessment of human decomposition is not possible, the sensible substitution is color photographic images. To date, no research has confirmed the utility of color photographic images as a proxy for in situ observation of the level of decomposition. Sixteen observers scored photographs of 13 human cadavers in varying decomposition stages (PMI 2-186 days) using the Total Body Score system (total n = 929 observations). The on-site TBS was compared with recorded observations from digital color images using a paired samples t-test. The average difference between on-site and photographic observations was -0.20 (t = -1.679, df = 928, p = 0.094). Individually, only two observers, both students with <1 year of experience, demonstrated TBS statistically significantly different than the on-site value, suggesting that with experience, observations of human decomposition based on digital images can be substituted for assessments based on observation of the corpse in situ, when necessary.

  8. Comparing Temperature and Precipitation Extremes Across Multiple Reanalyses and Gridded in Situ Observational Datasets

    NASA Astrophysics Data System (ADS)

    Donat, M.; Alexander, L. V.; Sillmann, J.; Wild, S.; Zwiers, F. W.; Lippmann, T.

    2014-12-01

    Changes in climate extremes are often monitored using global gridded datasets of climate extremes based on in situ observations or reanalysis data. This study assesses the consistency of temperature and precipitation extremes between these datasets. We compare temporal evolution and spatial patterns of annual climate extremes indices across multiple global gridded datasets of in situ observations and reanalyses to make inferences on the robustness of the obtained results. While there are distinct differences in the actual values of extremes, normalized time series generally compare well and temporal correlations are high for temperature extremes, in particular for the most recent three decades when satellite data are available for assimilation. Extreme precipitation is characterized by higher temporal and spatial variability than extreme temperatures, and there is less agreement between different datasets than for temperature. However, reasonable agreement between gridded precipitation extremes from the different datasets remains. While there is general agreement between the different reanalyses and gridded observational data in regions with dense observational coverage, different reanalyses show trends of partly opposing signs in areas where in situ observations are sparse, e.g. over parts of Africa and tropical South America. However, in the absence of reliable observations it is difficult to assess which reanalyses are more realistic here than others. Using data from the 20th Century reanalysis and a novel century-long gridded dataset of extremes we also investigate consistency of extremes from these two datasets back to the beginning of the 20th Century. Global average time series of different extremes indices compare generally well over the past 70 years but show larger differences before around 1940. However, in areas with good observational coverage, including North America, Europe and Australia, agreement remains strong also throughout the earlier decades

  9. Regression modeling of longitudinal data with outcome-dependent observation times: extensions and comparative evaluation.

    PubMed

    Tan, Kay See; French, Benjamin; Troxel, Andrea B

    2014-11-30

    Conventional longitudinal data analysis methods assume that outcomes are independent of the data-collection schedule. However, the independence assumption may be violated, for example, when a specific treatment necessitates a different follow-up schedule than the control arm or when adverse events trigger additional physician visits in between prescheduled follow-ups. Dependence between outcomes and observation times may introduce bias when estimating the marginal association of covariates on outcomes using a standard longitudinal regression model. We formulate a framework of outcome-observation dependence mechanisms to describe conditional independence given observed observation-time process covariates or shared latent variables. We compare four recently developed semi-parametric methods that accommodate one of these mechanisms. To allow greater flexibility, we extend these methods to accommodate a combination of mechanisms. In simulation studies, we show how incorrectly specifying the outcome-observation dependence may yield biased estimates of covariate-outcome associations and how our proposed extensions can accommodate a greater number of dependence mechanisms. We illustrate the implications of different modeling strategies in an application to bladder cancer data. In longitudinal studies with potentially outcome-dependent observation times, we recommend that analysts carefully explore the conditional independence mechanism between the outcome and observation-time processes to ensure valid inference regarding covariate-outcome associations.

  10. GRACE principles: recognizing high-quality observational studies of comparative effectiveness.

    PubMed

    Dreyer, Nancy A; Schneeweiss, Sebastian; McNeil, Barbara J; Berger, Marc L; Walker, Alec M; Ollendorf, Daniel A; Gliklich, Richard E

    2010-06-01

    Nonrandomized comparative effectiveness studies contribute to clinical and biologic understanding of treatments by themselves, via subsequent confirmation in a more targeted randomized clinical trial, or through advances in basic science. Although methodological challenges and a lack of accepted principles to assess the quality of nonrandomized studies of comparative effectiveness have limited the practical use of these investigations, even imperfect studies can contribute useful information if they are thoughtfully designed, well conducted, carefully analyzed, and reported in a manner that addresses concerns from skeptical readers and reviewers. The GRACE (Good Research for Comparative Effectiveness) principles have been developed to help healthcare providers, researchers, journal readers, and editors evaluate the quality inherent in observational research studies of comparative effectiveness. The GRACE principles were developed by experienced academic and private sector researchers and were vetted over several years through presentation, critique, and consensus building among outcomes researchers, pharmacoepidemiologists, and other medical scientists and via formal review by the International Society of Pharmacoepidemiology. In contrast to other documents that guide systematic review and reporting, the GRACE principles are high-level concepts about good practice for nonrandomized comparative effectiveness research. The GRACE principles comprise a series of questions to guide evaluation. No scoring system is provided or encouraged, as interpretation of these observational studies requires weighing of all available evidence, tempered by judgment regarding the applicability of the studies to routine care.

  11. Demystifying the Enigma of Smoking – An Observational Comparative Study on Tobacco Smoking

    PubMed Central

    Nallakunta, Rajesh; Reddy, Sudhakara Reddy; Chennoju, Sai Kiran

    2016-01-01

    Introduction Smoking is a hazardous habit which causes definite changes in the oral cavity, consequently there exist changes in the mucosa when subjected to smoking. Palatal mucosa is first to be affected. The present study determines the palatal status in reverse smokers and conventional smokers. Aim To study and compare the clinical, cytological and histopathological changes in palatal mucosa among reverse and conventional smokers. Materials and Methods Study sample was categorized into two groups. Group 1 comprised of 20 subjects with the habit of reverse smoking and Group 2 comprised of 20 subjects with the habit of conventional smoking. Initially, clinical appearance of the palatal mucosa was recorded, followed by a cytological smear and biopsy of the involved area among all the subjects. The findings were studied clinically, the specimens were analysed cytologically and histopathologically, and compared among the two groups. Results The severity of clinical changes of the palatal mucosa among reverse smokers was statistically significant when compared to those of conventional smokers. There was no statistically significant difference observed in cytological staging between the groups with a p-value of 0.35. The histopathological changes in both the groups showed a significant difference with a p-value of 0.02. A significant positive correlation was observed between the clinical appearance, and cytological, histopathological changes. Conclusion Profound clinically aggressive changes were observed in group I compared to group II. Severity of dysplastic changes have been detected in few subjects through histopathological examination irrespective of no prominent clinical and cytological changes observed among the two groups. PMID:27190962

  12. An Automated Comparative Observation System for Sun-Induced Chlorophyll Fluorescence of Vegetation Canopies

    PubMed Central

    Zhou, Xijia; Liu, Zhigang; Xu, Shan; Zhang, Weiwei; Wu, Jun

    2016-01-01

    Detecting sun-induced chlorophyll fluorescence (SIF) offers a new approach for remote sensing photosynthesis. However, to analyse the response characteristics of SIF under different stress states, a long-term time-series comparative observation of vegetation under different stress states must be carried out at the canopy scale, such that the similarities and differences in SIF change law can be summarized under different time scales. A continuous comparative observation system for vegetation canopy SIF is designed in this study. The system, which is based on a high-resolution spectrometer and an optical multiplexer, can achieve comparative observation of multiple targets. To simultaneously measure the commonly used vegetation index and SIF in the O2-A and O2-B atmospheric absorption bands, the following parameters are used: a spectral range of 475.9 to 862.2 nm, a spectral resolution of approximately 0.9 nm, a spectral sampling interval of approximately 0.4 nm, and the signal-to-noise ratio (SNR) can be as high as 1000:1. To obtain data for both the upward radiance of the vegetation canopy and downward irradiance data with a high SNR in relatively short time intervals, the single-step integration time optimization algorithm is proposed. To optimize the extraction accuracy of SIF, the FluorMOD model is used to simulate sets of data according to the spectral resolution, spectral sampling interval and SNR of the spectrometer in this continuous observation system. These data sets are used to determine the best parameters of Fraunhofer Line Depth (FLD), Three FLD (3FLD) and the spectral fitting method (SFM), and 3FLD and SFM are confirmed to be suitable for extracting SIF from the spectral measurements. This system has been used to observe the SIF values in O2-A and O2-B absorption bands and some commonly used vegetation index from sweet potato and bare land, the result of which shows: (1) the daily variation trend of SIF value of sweet potato leaves is basically same

  13. An Automated Comparative Observation System for Sun-Induced Chlorophyll Fluorescence of Vegetation Canopies.

    PubMed

    Zhou, Xijia; Liu, Zhigang; Xu, Shan; Zhang, Weiwei; Wu, Jun

    2016-05-27

    Detecting sun-induced chlorophyll fluorescence (SIF) offers a new approach for remote sensing photosynthesis. However, to analyse the response characteristics of SIF under different stress states, a long-term time-series comparative observation of vegetation under different stress states must be carried out at the canopy scale, such that the similarities and differences in SIF change law can be summarized under different time scales. A continuous comparative observation system for vegetation canopy SIF is designed in this study. The system, which is based on a high-resolution spectrometer and an optical multiplexer, can achieve comparative observation of multiple targets. To simultaneously measure the commonly used vegetation index and SIF in the O₂-A and O₂-B atmospheric absorption bands, the following parameters are used: a spectral range of 475.9 to 862.2 nm, a spectral resolution of approximately 0.9 nm, a spectral sampling interval of approximately 0.4 nm, and the signal-to-noise ratio (SNR) can be as high as 1000:1. To obtain data for both the upward radiance of the vegetation canopy and downward irradiance data with a high SNR in relatively short time intervals, the single-step integration time optimization algorithm is proposed. To optimize the extraction accuracy of SIF, the FluorMOD model is used to simulate sets of data according to the spectral resolution, spectral sampling interval and SNR of the spectrometer in this continuous observation system. These data sets are used to determine the best parameters of Fraunhofer Line Depth (FLD), Three FLD (3FLD) and the spectral fitting method (SFM), and 3FLD and SFM are confirmed to be suitable for extracting SIF from the spectral measurements. This system has been used to observe the SIF values in O₂-A and O₂-B absorption bands and some commonly used vegetation index from sweet potato and bare land, the result of which shows: (1) the daily variation trend of SIF value of sweet potato leaves is

  14. Comparing the diameters and visual albedos derived from radar and infrared observations

    NASA Astrophysics Data System (ADS)

    Taylor, P.; Howell, E.; Nolan, M.; Springmann, A.; Vervack, R., Jr.; Fernandez, Y.; Magri, C.

    2014-07-01

    Radar observations provide direct measurements of the physical sizes of near-Earth objects, independent of visual albedo, composition, and thermal properties, which can act as calibration or sanity checks for models of thermal-infrared emission by small bodies. Thermal modeling of infrared observations by the NEOWISE [1--3] and ExploreNEOs (Spitzer) [4--6] programs has provided diameters and visual albedos for several hundred near-Earth objects. Meanwhile, since 1998, the Arecibo radar program has detected over 350 near-Earth objects, including more than 40 objects from each of the NEOWISE and ExploreNEOs catalogs, providing rotation-rate, size, and shape constraints depending on the strength and resolution of the received echoes. In addition, our observations with the SpeX instrument on the NASA IRTF provide a sample of roughly two dozen objects, observed on multiple dates at different viewing geometries, that were also observed by the Arecibo radar and NEOWISE and/or ExploreNEOs programs. We will compare the diameters and visual albedos inferred from radar to those derived from thermal modeling of infrared observations from WISE, Spitzer, and/or the IRTF, and look for correlations between the outliers and their sizes, shapes, compositions, and viewing geometries, all of which can affect the assumptions made in the process of standard thermal modeling.

  15. Comparing USGS national seismic hazard maps with internet-based macroseismic intensity observations

    NASA Astrophysics Data System (ADS)

    Mak, Sum; Schorlemmer, Danijel

    2016-04-01

    Verifying a nationwide seismic hazard assessment using data collected after the assessment has been made (i.e., prospective data) is a direct consistency check of the assessment. We directly compared the predicted rate of ground motion exceedance by the four available versions of the USGS national seismic hazard map (NSHMP, 1996, 2002, 2008, 2014) with the actual observed rate during 2000-2013. The data were prospective to the two earlier versions of NSHMP. We used two sets of somewhat independent data, namely 1) the USGS "Did You Feel It?" (DYFI) intensity reports, 2) instrumental ground motion records extracted from ShakeMap stations. Although both are observed data, they come in different degrees of accuracy. Our results indicated that for California, the predicted and observed hazards were very comparable. The two sets of data gave consistent results, implying robustness. The consistency also encourages the use of DYFI data for hazard verification in the Central and Eastern US (CEUS), where instrumental records are lacking. The result showed that the observed ground-motion exceedance was also consistent with the predicted in CEUS. The primary value of this study is to demonstrate the usefulness of DYFI data, originally designed for community communication instead of scientific analysis, for the purpose of hazard verification.

  16. Anatomical knowledge gain through a clay-modeling exercise compared to live and video observations.

    PubMed

    Kooloos, Jan G M; Schepens-Franke, Annelieke N; Bergman, Esther M; Donders, Rogier A R T; Vorstenbosch, Marc A T M

    2014-01-01

    Clay modeling is increasingly used as a teaching method other than dissection. The haptic experience during clay modeling is supposed to correspond to the learning effect of manipulations during exercises in the dissection room involving tissues and organs. We questioned this assumption in two pretest-post-test experiments. In these experiments, the learning effects of clay modeling were compared to either live observations (Experiment I) or video observations (Experiment II) of the clay-modeling exercise. The effects of learning were measured with multiple choice questions, extended matching questions, and recognition of structures on illustrations of cross-sections. Analysis of covariance with pretest scores as the covariate was used to elaborate the results. Experiment I showed a significantly higher post-test score for the observers, whereas Experiment II showed a significantly higher post-test score for the clay modelers. This study shows that (1) students who perform clay-modeling exercises show less gain in anatomical knowledge than students who attentively observe the same exercise being carried out and (2) performing a clay-modeling exercise is better in anatomical knowledge gain compared to the study of a video of the recorded exercise. The most important learning effect seems to be the engagement in the exercise, focusing attention and stimulating time on task.

  17. A comparative study of multiwavelength theoretical and observed light curves of Cepheid variables

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Anupam; Kanbur, Shashi M.; Marconi, Marcella; Rejkuba, Marina; Singh, Harinder P.; Ngeow, Chow-Choong

    2017-04-01

    We analyse the theoretical light curves of Cepheid variables at optical (UBVRI) and near-infrared (JKL) wavelengths using the Fourier decomposition and principal component analysis methods. The Cepheid light curves are based on the full-amplitude, non-linear, convective hydrodynamical models for chemical compositions representative of Cepheids in the Galaxy (Y = 0.28, Z = 0.02), Large Magellanic Cloud (Y = 0.25, Z = 0.008) and Small Magellanic Cloud (Y = 0.25, Z = 0.004). We discuss the variation of light-curve parameters with different compositions and mass-luminosity levels as a function of period and wavelength, and compare our results with observations. For a fixed composition, the theoretical amplitude parameters decrease while the phase parameters increase with wavelength, similar to the observed Fourier parameters. The optical amplitude parameters obtained using canonical mass-luminosity Cepheid models exhibit a large offset with respect to the observations for periods between 7 and 11 d, when compared to the non-canonical mass-luminosity levels. The central minimum of the Hertzsprung progression for amplitude parameters shifts to the longer periods with decrease/increase in metallicity/wavelength for both theoretical and observed light curves. The principal components for Magellanic Cloud Cepheid models are consistent with observations at optical wavelengths. We also observe two distinct populations in the first principal component for optical and near-infrared wavelengths while the J band contributes to both populations. Finally, we take into account the variation in the convective efficiency by increasing the adopted mixing length parameter from the standard 1.5 to 1.8. This results in a zero-point offset in the bolometric mean magnitudes and in amplitude parameters (except close to 10 d), reducing the systematically large difference in theoretical amplitudes.

  18. Comparing Aircraft Observations of Snowfall to Forecasts Using Single or Two Moment Bulk Water Microphysics Schemes

    NASA Technical Reports Server (NTRS)

    Molthan, Andrew L.

    2010-01-01

    High resolution weather forecast models with explicit prediction of hydrometeor type, size distribution, and fall speed may be useful in the development of precipitation retrievals, by providing representative characteristics of frozen hydrometeors. Several single or double-moment microphysics schemes are currently available within the Weather Research and Forecasting (WRF) model, allowing for the prediction of up to three ice species. Each scheme incorporates different assumptions regarding the characteristics of their ice classes, particularly in terms of size distribution, density, and fall speed. In addition to the prediction of hydrometeor content, these schemes must accurately represent the vertical profile of water vapor to account for possible attenuation, along with the size distribution, density, and shape characteristics of ice crystals that are relevant to microwave scattering. An evaluation of a particular scheme requires the availability of field campaign measurements. The Canadian CloudSat/CALIPSO Validation Project (C3VP) obtained measurements of ice crystal shapes, size distributions, fall speeds, and precipitation during several intensive observation periods. In this study, C3VP observations obtained during the 22 January 2007 synoptic-scale snowfall event are compared against WRF model output, based upon forecasts using four single-moment and two double-moment schemes available as of version 3.1. Schemes are compared against aircraft observations by examining differences in size distribution, density, and content. In addition to direct measurements from aircraft probes, simulated precipitation can also be converted to equivalent, remotely sensed characteristics through the use of the NASA Goddard Satellite Data Simulator Unit. Outputs from high resolution forecasts are compared against radar and satellite observations emphasizing differences in assumed crystal shape and size distribution characteristics.

  19. The energy budget of stellar magnetic fields: comparing non-potential simulations and observations

    NASA Astrophysics Data System (ADS)

    Lehmann, L. T.; Jardine, M. M.; Vidotto, A. A.; Mackay, D. H.; See, V.; Donati, J.-F.; Folsom, C. P.; Jeffers, S. V.; Marsden, S. C.; Morin, J.; Petit, P.

    2017-03-01

    The magnetic geometry of the surface magnetic fields of more than 55 cool stars have now been mapped using spectropolarimetry. In order to better understand these observations, we compare the magnetic field topology at different surface scale sizes of observed and simulated cool stars. For ease of comparison between the high-resolution non-potential magnetofrictional simulations and the relatively low-resolution observations, we filter out the small-scale field in the simulations using a spherical harmonics decomposition. We show that the large-scale field topologies of the solar-based simulations produce values of poloidal/toroidal fields and fractions of energy in axisymmetric modes which are similar to the observations. These global non-potential evolution model simulations capture key magnetic features of the observed solar-like stars through the processes of surface flux transport and magnetic flux emergence. They do not, however, reproduce the magnetic field of M-dwarfs or stars with dominantly toroidal field. Furthermore, we analyse the magnetic field topologies of individual spherical harmonics for the simulations and discover that the dipole is predominately poloidal, while the quadrupole shows the highest fraction of toroidal fields. Magnetic field structures smaller than a quadrupole display a fixed ratio between the poloidal and toroidal magnetic energies.

  20. Mid-Continental Intensive Field Campaign Atmospheric CO2 Observations Compared to Forward Models

    NASA Astrophysics Data System (ADS)

    Diaz, L. I.; Davis, K. J.; Miles, N. L.; Richardson, S.; Schuh, A. E.; Denning, A.; Andrews, A. E.; Jacobson, A. R.; Corbin, K.

    2009-12-01

    Two commonly used approaches to study source/sinks of CO2 are the “bottom-up” and the “top-down” methods. Because of the large discrepancies between these approaches, the North America Carbon Program devised the Mid-Continental Intensive field campaign (MCI). The MCI campaign aims at improving the carbon flux estimates of both approaches with a combination of atmospheric transport models, a denser network of in-situ atmospheric CO2 measurements and agricultural inventories. The first step in evaluating and improving inverse models is to compare observed CO2 concentrations and predicted concentrations from forwards models. This study shows a model-data comparison at multiple temporal and spatial scales for the 2007 growing season. In-situ tower-based observations are compared to two different forwards models: NOAA’s Carbon Tracker and CSU’s SiBcrop-RAMS. Observations from two tall towers of the National Oceanic and Atmospheric Administration (NOAA) and five towers of Ring2 PSU network are used for this comparison. The towers are located in an intensively agricultural region of the North American continent. Comparisons to date show that both models predict higher mid-summer concentrations at three sites located in the “corn belt.” Both models have difficulty reproducing the observed monthly-average spatial gradient across these sites. The models also underestimate the maximum observed spatial gradients in daytime, daily-averaged boundary layer concentrations. These results suggest that the rapid photosynthetic rates found in corn are not yet well-simulated in these models, and that these data, when used in inversions, will provide a valuable constraint on regional fluxes.

  1. Comparing different Ultraviolet Imaging Spectrograph (UVIS) occultation observations using modeling of water vapor jets

    NASA Astrophysics Data System (ADS)

    Portyankina, Ganna; Esposito, Larry W.; Hansen, Candice; Aye, Klaus-Michael

    2016-10-01

    Motivation: On March 11, 2016 the Cassini UVIS observed its 6th star occultation by Enceladus' plume. This observation was aimed to determine variability in the total gas flux from the Enceladus' southern polar region. The analysis of the received data suggests that the total gas flux is moderately increased comparing to the average gas flux observed by UVIS from 2005 to 2011 [1]. However, UVIS detected variability in individual jets. In particular, Baghdad 1 is more collimated in 2016 than in 2005, meaning its gas escapes at higher velocity.Model and fits: We use 3D DSMC model for water vapor jets to compare different UVIS occultation observations from 2005 to 2016. The model traces test articles from jets' sources [2] into space and results in coordinates and velocities for a set of test particles. We convert particle positions into the particle number density and integrate along UVIS line of sight (LoS) for each time step of the UVIS observation using precise observational geometry derived from SPICE [3]. We integrate all jets that are crossed by the LoS and perform constrained least-squares fit of resulting modeled opacities to the observed data to solved for relative strengths of jets. The geometry of each occultation is specific, for example, during solar occultation in 2010 UVIS LoS was almost parallel to tiger stripes, which made it possible to distinguish jets venting from different tiger stripes. In 2011 Eps Orionis occultation LoS was perpendicular to tiger stripes and thus many of the jets were geometrically overlapping. Solar occultation provided us with the largest inventory of active jets - our model fit detects at least 43 non-zero jet contributions. Stellar occultations generally have lower temporal resolution and observe only a sub-set of these jets: 2011 Eps Orionis needs minimum 25 non-zero jets to fit UVIS data. We will discuss different occultations and models fits, including the most recent Epsilon Orionis occultation of 2016.[1] Hansen et al

  2. Bayesian Techniques for Comparing Time-dependent GRMHD Simulations to Variable Event Horizon Telescope Observations

    NASA Astrophysics Data System (ADS)

    Kim, Junhan; Marrone, Daniel P.; Chan, Chi-Kwan; Medeiros, Lia; Özel, Feryal; Psaltis, Dimitrios

    2016-12-01

    The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long-baseline interferometry (VLBI) experiment that is capable of observing black holes with horizon-scale resolution. Early observations have revealed variable horizon-scale emission in the Galactic Center black hole, Sagittarius A* (Sgr A*). Comparing such observations to time-dependent general relativistic magnetohydrodynamic (GRMHD) simulations requires statistical tools that explicitly consider the variability in both the data and the models. We develop here a Bayesian method to compare time-resolved simulation images to variable VLBI data, in order to infer model parameters and perform model comparisons. We use mock EHT data based on GRMHD simulations to explore the robustness of this Bayesian method and contrast it to approaches that do not consider the effects of variability. We find that time-independent models lead to offset values of the inferred parameters with artificially reduced uncertainties. Moreover, neglecting the variability in the data and the models often leads to erroneous model selections. We finally apply our method to the early EHT data on Sgr A*.

  3. Simulations of Solar Induced Fluorescence compared to observations from GOSAT and GOME-2 Satellites

    NASA Astrophysics Data System (ADS)

    Baker, I. T.; Berry, J. A.; Frankenberg, C.; Joiner, J.; Van der Tol, C.; Lee, J. E.; Denning, S.

    2014-12-01

    Observations of Solar-Induced Fluorescence (SIF) are currently retrieved from the GOSAT and GOME-2 satellites, and will become available from OCO-2 shortly. The GOSAT (and OCO-2) satellite has a midday overpass time, while GOME-2 has a variable observation of approximately 0800-1100 local time. Previous studies have demonstrated a linear relationship between SIF and Gross Primary Productivity (GPP), but lack the ability to investigate causes of spatiotemporal variability. We demonstrate an ability to simulate SIF using a landsurface model (the Simple Biosphere Model; SIB) for direct comparison to observations. We calculate fluorescence yield based on known relationships between photosynthesis and fluorescence, and calculate total SIF using existing leaf-to-canopy scaling factors. We find that simulated SIF exceeds GOSAT retrieved SIF, especially in tropical and Boreal forests. Simulated SIF exceeds GOME-2 values in Boreal forest and in lower-productivity areas such as marginal desert and tundra. Observed SIF GOME-2 in croplands is significantly higher than simulations. SIF simulated for low- and high-productivity grassland and savanna show much less seasonal and interannual amplitude when compared to values from both satellites, implicating that model phenology and/or response to meteorological forcing is damped. Simulated SIF seasonal cycles are similar to observed from both satellites, and simulations are able to reproduce drought events such as occurred in Russia in 2010 and the Central USA in 2012. As simulated SIF more closely resembles observations, model estimates of GPP become more robust, as does our ability to understand and recreate the mechanisms involved in vegetation response to seasonal cycles and anomalous stress events such as drought.

  4. Comparing a Carbon Budget for the Amazon Basin Derived from Aircraft Observations

    NASA Astrophysics Data System (ADS)

    Chow, V. Y.; Dayalu, A.; Wofsy, S. C.; Gerbig, C.

    2015-12-01

    We present and compare a carbon budget for the Brazilian Amazon Basin based on the Balanço Atmosférico Regional de Carbono na Amazônia (BARCA) aircraft program, which occurred in November 2008 & May 2009, to other published carbon budgets. In particular, we compare our budget and analysis to others also derived from aircraft observations. Using mesoscale meteorological fields from ECMWF and WRF, we drive the Stochastic Time-Inverted Lagrangian Transport (STILT) model and couple the footprint, or influence, to a biosphere model represented by the Vegetation Photosynthesis Respiration Model (VPRM). Since it is the main driver for the VPRM, we use observed shortwave radiation from towers in Brazil and French Guyana to examine the modeled shortwave radiation data from GL 1.2 (a global radiation model based on GOES 8 visible imagery), ECMWF, and WRF to determine if there are any biases in the modeled shortwave radiation output. We use WRF-STILT and ECMWF-STILT, GL 1.2 shortwave radiation, temperature, and vegetation maps (IGBP and SYNMAP) updated by landuse scenarios modeled by Sim Amazonia 2 and Sim Brazil, to compute hourly a priori CO2 fluxes by calculating Gross Ecosystem Exchange and Respiration for the 4 significant vegetation types across two (wet and dry) seasons as defined by 10-years of averaged TRIMM precipitation data. SF6 from stations and aircraft observations are used to determine the anthropogenic CO2 background and the lateral boundary conditions are taken from CarbonTracker2013B. The BARCA aircraft mixing ratios are then used as a top down constraint in an inversion framework that solves for the parameters controlling the fluxes for each vegetation type. The inversion provides scaling factors for GEE and R for each vegetation type in each season. From there, we derive a budget for the Basin and compare/contrast with other published basinwide CO2 fluxes.

  5. Ion cyclotron instability at Io: Hybrid simulation results compared to in situ observations

    NASA Astrophysics Data System (ADS)

    Šebek, Ondřej; Trávníček, Pavel M.; Walker, Raymond J.; Hellinger, Petr

    2016-08-01

    We present analysis of global three-dimensional hybrid simulations of Io's interaction with Jovian magnetospheric plasma. We apply a single-species model with simplified neutral-plasma chemistry and downscale Io in order to resolve the ion kinetic scales. We consider charge exchange, electron impact ionization, and photoionization by using variable rates of these processes to investigate their impact. Our results are in a good qualitative agreement with the in situ magnetic field measurements for five Galileo flybys around Io. The hybrid model describes ion kinetics self-consistently. This allows us to assess the distribution of temperature anisotropies around Io and thereby determine the possible triggering mechanism for waves observed near Io. We compare simulated dynamic spectra of magnetic fluctuations with in situ observations made by Galileo. Our results are consistent with both the spatial distribution and local amplitude of magnetic fluctuations found in the observations. Cyclotron waves, triggered probably by the growth of ion cyclotron instability, are observed mainly downstream of Io and on the flanks in regions farther from Io where the ion pickup rate is relatively low. Growth of the ion cyclotron instability is governed mainly by the charge exchange rate.

  6. COMPARING THE LIGHT CURVES OF SIMULATED TYPE Ia SUPERNOVAE WITH OBSERVATIONS USING DATA-DRIVEN MODELS

    SciTech Connect

    Diemer, Benedikt; Kessler, Richard; Graziani, Carlo; Jordan, George C. IV; Lamb, Donald Q.; Long, Min; Van Rossum, Daniel R.

    2013-08-20

    We propose a robust, quantitative method to compare the synthetic light curves of a Type Ia supernova (SN Ia) explosion model with a large set of observed SNe Ia, and derive a figure of merit for the explosion model's agreement with observations. The synthetic light curves are fit with the data-driven model SALT2 which returns values for stretch, color, and magnitude at peak brightness, as well as a goodness-of-fit parameter. Each fit is performed multiple times with different choices of filter bands and epoch range in order to quantify the systematic uncertainty on the fitted parameters. We use a parametric population model for the distribution of observed SN Ia parameters from large surveys, and extend it to represent red, dim, and bright outliers found in a low-redshift SN Ia data set. We discuss the potential uncertainties of this population model and find it to be reliable given the current uncertainties on cosmological parameters. Using our population model, we assign each set of fitted parameters a likelihood of being observed in nature, and a figure of merit based on this likelihood. We define a second figure of merit based on the quality of the light curve fit, and combine the two measures into an overall figure of merit for each explosion model. We compute figures of merit for a variety of one-, two-, and three-dimensional explosion models and show that our evaluation method allows meaningful inferences across a wide range of light curve quality and fitted parameters.

  7. Quality standards for real-world research. Focus on observational database studies of comparative effectiveness.

    PubMed

    Roche, Nicolas; Reddel, Helen; Martin, Richard; Brusselle, Guy; Papi, Alberto; Thomas, Mike; Postma, Dirjke; Thomas, Vicky; Rand, Cynthia; Chisholm, Alison; Price, David

    2014-02-01

    Real-world research can use observational or clinical trial designs, in both cases putting emphasis on high external validity, to complement the classical efficacy randomized controlled trials (RCTs) with high internal validity. Real-world research is made necessary by the variety of factors that can play an important a role in modulating effectiveness in real life but are often tightly controlled in RCTs, such as comorbidities and concomitant treatments, adherence, inhalation technique, access to care, strength of doctor-caregiver communication, and socio-economic and other organizational factors. Real-world studies belong to two main categories: pragmatic trials and observational studies, which can be prospective or retrospective. Focusing on comparative database observational studies, the process aimed at ensuring high-quality research can be divided into three parts: preparation of research, analyses and reporting, and discussion of results. Key points include a priori planning of data collection and analyses, identification of appropriate database(s), proper outcomes definition, study registration with commitment to publish, bias minimization through matching and adjustment processes accounting for potential confounders, and sensitivity analyses testing the robustness of results. When these conditions are met, observational database studies can reach a sufficient level of evidence to help create guidelines (i.e., clinical and regulatory decision-making).

  8. Propensity score models in observational comparative effectiveness studies: cornerstone of design or statistical afterthought?

    PubMed

    Robinson, John W

    2012-03-01

    Propensity score models are increasingly used in observational comparative effectiveness studies to reduce confounding by covariates that are associated with both a study outcome and treatment choice. Any such potentially confounding covariate will bias estimation of the effect of treatment on the outcome, unless the distribution of that covariate is well-balanced between treatment and control groups. Constructing a subsample of treated and control subjects who are matched on estimated propensity scores is a means of achieving such balance for covariates that are included in the propensity score model. If, during study design, investigators assemble a comprehensive inventory of known and suspected potentially confounding covariates, examination of how well this inventory is covered by the chosen dataset yields an assessment of the extent of bias reduction that is possible by matching on estimated propensity scores. These considerations are explored by examining the designs of three recently published comparative effectiveness studies.

  9. Designing premarket observational comparative studies using existing data as controls: challenges and opportunities.

    PubMed

    Yue, Lilly Q; Lu, Nelson; Xu, Yunling

    2014-01-01

    Due to the special nature of medical device clinical studies, observational (nonrandomized) comparative studies play important roles in the premarket safety/effectiveness evaluation of medical devices. While historical data collected in earlier investigational device exemption studies of a previously approved medical device have been used to form control groups in comparative studies, high-quality registry data are emerging to provide opportunities for the premarket evaluation of new devices. However, in such studies, various biases could be introduced in every stage and aspect of study and may compromise the objectivity of study design and validity of study results. In this article, challenges and opportunities in the design of such studies using propensity score methodology are discussed from regulatory perspectives.

  10. Morphological and functional MDCT: problem-solving tool and surrogate biomarker for hepatic disease clinical care and drug discovery in the era of personalized medicine.

    PubMed

    Wang, Liang

    2010-08-17

    This article explains the significant role of morphological and functional multidetector computer tomography (MDCT) in combination with imaging postprocessing algorithms served as a problem-solving tool and noninvasive surrogate biomarker to effectively improve hepatic diseases characterization, detection, tumor staging and prognosis, therapy response assessment, and novel drug discovery programs, partial liver resection and transplantation, and MDCT-guided interventions in the era of personalized medicine. State-of-the-art MDCT depicts and quantifies hepatic disease over conventional CT for not only depicting lesion location, size, and extent but also detecting changes in tumor biologic behavior caused by therapy or tumor progression before morphologic changes. Color-encoded parameter display provides important functional information on blood flow, permeability, leakage space, and blood volume. Together with other relevant biomarkers and genomics, the imaging modality is being developed and validated as a biomarker to early response to novel, targeted anti-VEGF(R)/PDGFR or antivascular/angiogenesis agents as its parameters correlate with immunohistochemical surrogates of tumor angiogenesis and molecular features of malignancies. MDCT holds incremental value to World Health Organization response criteria and Response Evaluation Criteria in Solid Tumors in liver disease management. MDCT volumetric measurement of future remnant liver is the most important factor influencing the outcome of patients who underwent partial liver resection and transplantation. MDCT-guided interventional methods deliver personalized therapies locally in the human body. MDCT will hold more scientific impact when it is fused with other imaging probes to yield comprehensive information regarding changes in liver disease at different levels (anatomic, metabolic, molecular, histologic, and other levels).

  11. Comparing Simulations and Observations of Galaxy Evolution: Methods for Constraining the Nature of Stellar Feedback

    NASA Astrophysics Data System (ADS)

    Hummels, Cameron

    Computational hydrodynamical simulations are a very useful tool for understanding how galaxies form and evolve over cosmological timescales not easily revealed through observations. However, they are only useful if they reproduce the sorts of galaxies that we see in the real universe. One of the ways in which simulations of this sort tend to fail is in the prescription of stellar feedback, the process by which nascent stars return material and energy to their immediate environments. Careful treatment of this interaction in subgrid models, so-called because they operate on scales below the resolution of the simulation, is crucial for the development of realistic galaxy models. Equally important is developing effective methods for comparing simulation data against observations to ensure galaxy models which mimic reality and inform us about natural phenomena. This thesis examines the formation and evolution of galaxies and the observable characteristics of the resulting systems. We employ extensive use of cosmological hydrodynamical simulations in order to simulate and interpret the evolution of massive spiral galaxies like our own Milky Way. First, we create a method for producing synthetic photometric images of grid-based hydrodynamical models for use in a direct comparison against observations in a variety of filter bands. We apply this method to a simulation of a cluster of galaxies to investigate the nature of the red-sequence/blue-cloud dichotomy in the galaxy color-magnitude diagram. Second, we implement several subgrid models governing the complex behavior of gas and stars on small scales in our galaxy models. Several numerical simulations are conducted with similar initial conditions, where we systematically vary the subgrid models, afterward assessing their efficacy through comparisons of their internal kinematics with observed systems. Third, we generate an additional method to compare observations with simulations, focusing on the tenuous circumgalactic

  12. A Numerical Study of Water Loss Rate Distributions in MDCT-based Human Airway Models

    PubMed Central

    Wu, Dan; Miyawaki, Shinjiro; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long

    2015-01-01

    Both three-dimensional (3D) and one-dimensional (1D) computational fluid dynamics (CFD) methods are applied to study regional water loss in three multi-detector row computed-tomography (MDCT)-based human airway models at the minute ventilations of 6, 15 and 30 L/min. The overall water losses predicted by both 3D and 1D models in the entire respiratory tract agree with available experimental measurements. However, 3D and 1D models reveal different regional water loss rate distributions due to the 3D secondary flows formed at bifurcations. The secondary flows cause local skewed temperature and humidity distributions on inspiration acting to elevate the local water loss rate; and the secondary flow at the carina tends to distribute more cold air to the lower lobes. As a result, the 3D model predicts that the water loss rate first increases with increasing airway generation, and then decreases as the air approaches saturation, while the 1D model predicts a monotonic decrease of water loss rate with increasing airway generation. Moreover, the 3D (or 1D) model predicts relatively higher water loss rates in lower (or upper) lobes. The regional water loss rate can be related to the non-dimensional wall shear stress (τ*) by the non-dimensional mass transfer coefficient (h0*) as h0* = 1.15 τ*0.272, R = 0.842. PMID:25869455

  13. Using radiative kernels to compare feedback behavior over different time scales in CMIP output and observations

    NASA Astrophysics Data System (ADS)

    Shell, K. M.; Flink, M. M.; Jonko, A. K.

    2011-12-01

    Accurate climate projections require an understanding of feedback behavior on centennial timescales. Unfortunately, satellite and reanalysis observations are available only for the last few decades. We seek to determine the extent to which the relatively short observation-based records can constrain model estimates of long-term (century-scale) climate change in response to anthropogenic forcing. The radiative kernel technique allows us to study feedbacks related to temperature, water vapor, surface albedo, and clouds in a consistent fashion. We are using Coupled Model Intercomparison Project (CMIP) simulations to determine whether (modeled) feedbacks differ for interannual- and decadal-scale versus centennial-scale climate change. We also are comparing short-term feedbacks derived from satellite (Atmospheric Infrared Sounder, AIRS) and reanalysis (ERA-Interim) data with modeled feedbacks. We use two strategies. The first is the standard kernel technique where feedbacks are determined by differencing mean variables between two states. Preliminary work with CMIP3 indicates that averaging periods (e.g., 10 years versus 20 years) can change feedback estimates by more 20%. In general, we expect longer averaging periods to result in more accurate estimates of feedbacks. However, transient GCMs runs (as well as observational data sets) may be only a few decades long. In these cases, we must determine the best averaging period to balance the increase of noise caused by a shorter averaging period and the decrease of climate signal resulting from averaging periods that are closer together. To address this issue, the second strategy is a modified kernel technique where anomalies from the mean climate are combined with the kernel for every month of the time series. This technique is more appropriate in cases where there is not a large external forcing. We are calculating feedbacks in the CMIP5 simulations using both strategies with different averaging periods and start

  14. Comparative observation of skeletal-dental abnormalities in wild, domestic, and laboratory rabbits.

    PubMed

    Okuda, Ayako; Hori, Yutaka; Ichihara, Nobutsune; Asari, Masao; Wiggs, Robert B

    2007-12-01

    Dietary habits must be considered as one of the major potential factors resulting in acquired malocclusions in rabbits. Although the dentition of the wild rabbit and the domesticated laboratory rabbit are basically identical, dietary habits are noticeably different. Therefore, the prevalence of tooth problems between these lagomorph species were investigated anatomically and radiographically. Mean measurements of the skull and dental arches suggested that wild rabbits have slightly shorter and wider skulls and dental arches compared with domestic laboratory rabbits. Root elongation of incisors and check teeth, and periodontal disease were more frequently observed in domestic laboratory rabbits. Diagnostic radiographs from domestic pet rabbits showed relatively higher crowns, severe root elongation, and advanced periodontitis. These results do not provide definitive evidence that dietary habits cause malocclusions, however they suggest that diet is a major factor in the initiation of malocclusions in rabbits.

  15. Comparative Analyses of the CSSS Calculation in the UCSD Tomographic Solar Observations

    NASA Astrophysics Data System (ADS)

    Dunn, T.; Jackson, B. V.; Hick, P. P.; Buffington, A.; Zhao, X. P.

    2005-04-01

    We describe a new method to derive the interplanetary magnetic field (IMF) out to 1 AU from photospheric magnetic field measurements. The method uses photospheric magnetograms to calculate a source surface magnetic field at 15R⊙. Specifically, we use Wilcox Solar Observatory (WSO) magnetograms as input for the Stanford Current-Sheet Source-Surface (CSSS) model. Beyond the source surface the magnetic field is convected along velocity flow lines derived by a tomographic technique developed at UCSD and applied to interplanetary scintillation (IPS) observations. We compare the results with in situ data smoothed by an 18-h running mean. Radial and tangential magnetic field amplitudes fit well for the 20 Carrington rotations studied, which are largely from the active phase of the solar cycle. We show exemplary results for Carrington rotation 1965, which includes the Bastille Day event.

  16. Statistical properties of a utility measure of observer performance compared to area under the ROC curve

    NASA Astrophysics Data System (ADS)

    Abbey, Craig K.; Samuelson, Frank W.; Gallas, Brandon D.; Boone, John M.; Niklason, Loren T.

    2013-03-01

    The receiver operating characteristic (ROC) curve has become a common tool for evaluating diagnostic imaging technologies, and the primary endpoint of such evaluations is the area under the curve (AUC), which integrates sensitivity over the entire false positive range. An alternative figure of merit for ROC studies is expected utility (EU), which focuses on the relevant region of the ROC curve as defined by disease prevalence and the relative utility of the task. However if this measure is to be used, it must also have desirable statistical properties keep the burden of observer performance studies as low as possible. Here, we evaluate effect size and variability for EU and AUC. We use two observer performance studies recently submitted to the FDA to compare the EU and AUC endpoints. The studies were conducted using the multi-reader multi-case methodology in which all readers score all cases in all modalities. ROC curves from the study were used to generate both the AUC and EU values for each reader and modality. The EU measure was computed assuming an iso-utility slope of 1.03. We find mean effect sizes, the reader averaged difference between modalities, to be roughly 2.0 times as big for EU as AUC. The standard deviation across readers is roughly 1.4 times as large, suggesting better statistical properties for the EU endpoint. In a simple power analysis of paired comparison across readers, the utility measure required 36% fewer readers on average to achieve 80% statistical power compared to AUC.

  17. Microphysical Simulations of Polar Stratospheric Clouds Compared with Calipso and MLS Observations

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Toon, O. B.; Kinnison, D. E.; Lambert, A.; Brakebusch, M.

    2014-12-01

    Polar stratospheric clouds (PSCs) form in the lower stratosphere during the polar night due to the cold temperature inside the polar vortex. PSCs are important to understand because they are responsible for the formation of the Antarctic ozone hole and the ozone depletion over the Arctic. In this work, we explore the formation and evolution of STS particles (Super-cooled Ternary Solution) and NAT (Nitric-acid Trihydrate) particles using the SD-WACCM/CARMA model. SD-WACCM/CARMA couples the Whole Atmosphere Community Climate Model using Specific Dynamics with the microphysics model (CARMA). The 2010-2011 Arctic winter has been simulated because the Arctic vortex remained cold enough for PSCs from December until the end of March (Manney et al., 2011). The unusual length of this cold period and the presence of PSCs caused strong ozone depletion. This model simulates the growth and evaporation of the STS particles instead of considering them as being in equilibrium as other models do (Carslaw et al., 1995). This work also explores the homogeneous nucleation of NAT particles and derives a scheme for NAT formation based on the observed denitrification during the winter 2010-2011. The simulated microphysical features (particle volumes, size distributions, etc.) of both STS (Supercooled Ternary Solutions) and NAT particles show a consistent comparison with historical observations. The modeled evolution of PSCs and gas phase ozone related chemicals inside the vortex such as HCl and ClONO2 are compared with the observations from MLS, MIPAS and CALIPSO over this winter. The denitrification history indicate the surface nucleation rate from Tabazadeh et al. (2002) removes too much HNO3 over the winter. With a small modification of the free energy term of the equation, the denitification and the PSC backscattering features are much closer to the observations. H2O, HCl, O3 and ClONO2 are very close to MLS and MIPAS observations inside the vortex. The model underestimates ozone

  18. The highs and lows of cloud radiative feedback: Comparing observational data and CMIP5 models

    NASA Astrophysics Data System (ADS)

    Jenney, A.; Randall, D. A.

    2014-12-01

    Clouds play a complex role in the climate system, and remain one of the more difficult aspects of the future climate to predict. Over subtropical eastern ocean basins, particularly next to California, Peru, and Southwest Africa, low marine stratocumulus clouds (MSC) help to reduce the amount of solar radiation that reaches the surface by reflecting incident sunlight. The climate feedback associated with these clouds is thought to be positive. This project looks at CMIP5 models and compares them to observational data from CERES and ERA-Interim to try and find observational evidence and model agreement for low, marine stratocumulus cloud feedback. Although current evidence suggests that the low cloud feedback is positive (IPCC, 2014), an analysis of the simulated relationship between July lower tropospheric stability (LTS) and shortwave cloud forcing in MSC regions suggests that this feedback is not due to changes in LTS. IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

  19. Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise

    PubMed Central

    Brown, Patrick T.; Li, Wenhong; Cordero, Eugene C.; Mauget, Steven A.

    2015-01-01

    The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much public and scientific attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible unforced states of the climate system (the Envelope of Unforced Noise; EUN). Typically, the EUN is derived from climate models themselves, but climate models might not accurately simulate the correct characteristics of unforced GMT variability. Here, we simulate a new, empirical, EUN that is based on instrumental and reconstructed surface temperature records. We compare the forced GMT signal produced by climate models to observations while noting the range of GMT values provided by the empirical EUN. We find that the empirical EUN is wide enough so that the interdecadal variability in the rate of global warming over the 20th century does not necessarily require corresponding variability in the rate-of-increase of the forced signal. The empirical EUN also indicates that the reduced GMT warming over the past decade or so is still consistent with a middle emission scenario's forced signal, but is likely inconsistent with the steepest emission scenario's forced signal. PMID:25898351

  20. COMPARING THE OBSERVABLE PROPERTIES OF DWARF GALAXIES ON AND OFF THE ANDROMEDA PLANE

    SciTech Connect

    Collins, Michelle L. M.; Martin, Nicolas F.; Rich, R. M.; Ibata, Rodrigo A.; Chapman, Scott C.; McConnachie, Alan W.; Ferguson, Annette M.; Irwin, Michael J.; Lewis, Geraint F.

    2015-01-20

    The thin, extended planes of satellite galaxies detected around both the Milky Way and Andromeda are not a natural prediction of the Λ-cold dark matter paradigm. Galaxies in these distinct planes may have formed and evolved in a different way (e.g., tidally) from their off-plane neighbors. If this were the case, one would expect the on- and off-plane dwarf galaxies in Andromeda to have experienced different evolutionary histories, which should be reflected by the chemistries, dynamics, and star formation histories of the two populations. In this work, we present new, robust kinematic observations for two on-plane M31 dwarf spheroidal galaxies (And XVI and XVII) and compile and compare all available observational metrics for the on- and off-plane dwarfs to search for a signal that would corroborate such a hypothesis. We find that, barring their spatial alignment, the on- and off-plane Andromeda dwarf galaxies are indistinguishable from one another, arguing against vastly different formative and evolutionary histories for these two populations.

  1. Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise.

    PubMed

    Brown, Patrick T; Li, Wenhong; Cordero, Eugene C; Mauget, Steven A

    2015-04-21

    The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much public and scientific attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible unforced states of the climate system (the Envelope of Unforced Noise; EUN). Typically, the EUN is derived from climate models themselves, but climate models might not accurately simulate the correct characteristics of unforced GMT variability. Here, we simulate a new, empirical, EUN that is based on instrumental and reconstructed surface temperature records. We compare the forced GMT signal produced by climate models to observations while noting the range of GMT values provided by the empirical EUN. We find that the empirical EUN is wide enough so that the interdecadal variability in the rate of global warming over the 20(th) century does not necessarily require corresponding variability in the rate-of-increase of the forced signal. The empirical EUN also indicates that the reduced GMT warming over the past decade or so is still consistent with a middle emission scenario's forced signal, but is likely inconsistent with the steepest emission scenario's forced signal.

  2. Comparing Vesta's Surface Roughness to the Moon Using Bistatic Radar Observations by the Dawn Mission

    NASA Astrophysics Data System (ADS)

    Palmer, E. M.; Heggy, E.; Kofman, W. W.; Moghaddam, M.

    2015-12-01

    The first orbital bistatic radar (BSR) observations of a small body have been conducted opportunistically by NASA's Dawn spacecraft at Asteroid Vesta using the telecommunications antenna aboard Dawn to transmit and the Deep Space Network 70-meter antennas on Earth to receive. Dawn's high-gain communications antenna continuously transmitted right-hand circularly polarized radio waves (4-cm wavelength), and due to the opportunistic nature of the experiment, remained in a fixed orientation pointed toward Earth throughout each BSR observation. As a consequence, Dawn's transmitted radio waves scattered from Vesta's surface just before and after each occultation of the Dawn spacecraft behind Vesta, resulting in surface echoes at highly oblique incidence angles of greater than 85 degrees, and a small Doppler shift of ~2 Hz between the carrier signal and surface echoes from Vesta. We analyze the power and Doppler spreading of Vesta's surface echoes to assess surface roughness, and find that Vesta's area-normalized radar cross section ranges from -8 to -17 dB, which is notably much stronger than backscatter radar cross section values reported for the Moon's limbs (-20 to -35 dB). However, our measurements correspond to the forward scattering regime--such that at high incidence, radar waves are expected to scatter more weakly from a rough surface in the backscatter direction than that which is scattered forward. Using scattering models of rough surfaces observed at high incidence, we report on the relative roughness of Vesta's surface as compared to the Moon and icy Galilean satellites. Through this, we assess the dominant processes that have influenced Vesta's surface roughness at centimeter and decimeter scales, which are in turn applicable to assisting future landing, sampling and orbital missions of other small bodies.

  3. Io's Volcanism: Thermo-Physical Models of Silicate Lava Compared with Observations of Thermal Emission

    NASA Technical Reports Server (NTRS)

    Davies, Ashely G.

    1996-01-01

    Analyses of thermal infrared outbursts from the jovian satellite Io indicate that at least some of these volcanic events are due to silicate lava. Analysis of the January 9, 1990 outburst indicates that this was an active eruption consisting of a large lava flow (with mass eruption rate of order 10(exp 5) cubic m/sec) and a sustained area at silicate liquidus temperatures. This is interpreted as a series of fire fountains along a rift zone. A possible alternative scenario is that of an overflowing lava lake with extensive fire fountaining. The January 9, 1990 event is unique as multispectral observations with respect to time were obtained. In this paper, a model is presented for the thermal energy lost by active and cooling silicate lava flows and lakes on Io. The model thermal emission is compared with Earth-based observations and Voyager IRIS data. The model (a) provides an explanation of the thermal anomalies on Io's surface; (b) provides constraints on flow behavior and extent and infers some flow parameters; and (c) determines flow geometry and change in flow size with time, and the temperature of each part of the flow or lava lake surface as a function of its age. Models of heat output from active lava flows or inactive but recently emplaced lava flows or overturning lava lakes alone are unable to reproduce the observations. If the January 9, 1990 event is the emplacement of a lava flow, the equivalent of 27 such events per year would yield a volume of material sufficient, if uniformly distributed, to resurface all of Io at a rate of 1 cm/year.

  4. Comparing human observer performance in detecting microcalcifications with energy weighting and photon counting breast CT

    NASA Astrophysics Data System (ADS)

    Kalluri, Kesava; Mahd, Mufeed; Glick, Stephen J.

    2012-03-01

    Breast CT (BCT) using a photon counting detector (PCD) has a number of advantages that can potentially improve clinical performance. Previous computer simulation studies showed that the signal to noise ratio (SNR) for microcalcifications is higher with energy weighted photon counting BCT as compared to cesium iodide energy integrating detector (CsI-EID) based BCT. CsI-EID inherently weighs the incident x-ray photons in direct proportion to the energy (contradicting the information content) which is not an optimal approach. PCD do not inherently weigh the incident photons. By choosing optimal energy weights, higher SNR can be achieved for microcalcifications and hence better detectability. In this simulation study, forward projection data of a numerical breast phantom with microcalcifications inserted were acquired using CsI-EID and PCD. The PCD projections were optimally weighed, and reconstructed using filtered back-projection. We compared observer performance in identifying microcalcifications in the reconstructed images using ROC analysis. ROC based results show that the average area(s) under curve(s) (AUC) for AUCPCD based methods are higher than the average AUCCsI-EID method.

  5. Potential for observing and discriminating impact craters and comparable volcanic landforms on Magellan radar images

    NASA Technical Reports Server (NTRS)

    Ford, J. P.

    1989-01-01

    Observations of small terrestrial craters by Seasat synthetic aperture radar (SAR) at high resolution (approx. 25 m) and of comparatively large Venusian craters by Venera 15/16 images at low resolution (1000 to 2000 m) and shorter wavelength show similarities in the radar responses to crater morphology. At low incidence angles, the responses are dominated by large scale slope effects on the order of meters; consequently it is difficult to locate the precise position of crater rims on the images. Abrupt contrasts in radar response to changing slope (hence incidence angle) across a crater produce sharp tonal boundaries normal to the illumination. Crater morphology that is radially symmetrical appears on images to have bilateral symmetry parallel to the illumination vector. Craters are compressed in the distal sector and drawn out in the proximal sector. At higher incidence angles obtained with the viewing geometry of SIR-A, crater morphology appears less compressed on the images. At any radar incidence angle, the distortion of a crater outline is minimal across the medial sector, in a direction normal to the illumination. Radar bright halos surround some craters imaged by SIR-A and Venera 15 and 16. The brightness probably denotes the radar response to small scale surface roughness of the surrounding ejecta blankets. Similarities in the radar responses of small terrestrial impact craters and volcanic craters of comparable dimensions emphasize the difficulties in discriminating an impact origin from a volcanic origin in the images. Similar difficulties will probably apply in discriminating the origin of small Venusian craters, if they exist. Because of orbital considerations, the nominal incidence angel of Magellan radar at the center of the imaging swath will vary from about 45 deg at 10 deg N latitude to about 16 deg at the north pole and at 70 deg S latitude. Impact craters and comparable volcanic landforms will show bilateral symmetry parallel to the illumination

  6. Creating a Common Data Model for Comparative Effectiveness with the Observational Medical Outcomes Partnership

    PubMed Central

    Resnic, F.S.; Robbins, S.L.; Denton, J.; Nookala, L.; Meeker, D.; Ohno-Machado, L.; Matheny, M.E.

    2015-01-01

    Summary Background Adoption of a common data model across health systems is a key infrastructure requirement to allow large scale distributed comparative effectiveness analyses. There are a growing number of common data models (CDM), such as Mini-Sentinel, and the Observational Medical Outcomes Partnership (OMOP) CDMs. Objectives In this case study, we describe the challenges and opportunities of a study specific use of the OMOP CDM by two health systems and describe three comparative effectiveness use cases developed from the CDM. Methods The project transformed two health system databases (using crosswalks provided) into the OMOP CDM. Cohorts were developed from the transformed CDMs for three comparative effectiveness use case examples. Administrative/billing, demographic, order history, medication, and laboratory were included in the CDM transformation and cohort development rules. Results Record counts per person month are presented for the eligible cohorts, highlighting differences between the civilian and federal datasets, e.g. the federal data set had more outpatient visits per person month (6.44 vs. 2.05 per person month). The count of medications per person month reflected the fact that one system’s medications were extracted from orders while the other system had pharmacy fills and medication administration records. The federal system also had a higher prevalence of the conditions in all three use cases. Both systems required manual coding of some types of data to convert to the CDM. Conclusions The data transformation to the CDM was time consuming and resources required were substantial, beyond requirements for collecting native source data. The need to manually code subsets of data limited the conversion. However, once the native data was converted to the CDM, both systems were then able to use the same queries to identify cohorts. Thus, the CDM minimized the effort to develop cohorts and analyze the results across the sites. PMID:26448797

  7. EuroInf: a multicenter comparative observational study of apomorphine and levodopa infusion in Parkinson's disease.

    PubMed

    Martinez-Martin, Pablo; Reddy, Prashanth; Katzenschlager, Regina; Antonini, Angelo; Todorova, Antoniya; Odin, Per; Henriksen, Tove; Martin, Anne; Calandrella, Daniela; Rizos, Alexandra; Bryndum, Narissah; Glad, Arne; Dafsari, Haidar Salimi; Timmermann, Lars; Ebersbach, Georg; Kramberger, Milica G; Samuel, Michael; Wenzel, Karoline; Tomantschger, Volker; Storch, Alexander; Reichmann, Heinz; Pirtosek, Zvezdan; Trost, Maja; Svenningsson, Per; Palhagen, Sven; Volkmann, Jens; Chaudhuri, K Ray

    2015-04-01

    Subcutaneous apomorphine infusion (Apo) and intrajejunal levodopa infusion (IJLI) are two treatment options for patients with advanced Parkinson's disease (PD) and refractory motor complications, with varying cost of treatment. There are no multicenter studies comparing the effects of the two strategies. This open-label, prospective, observational, 6-month, multicenter study compared 43 patients on Apo (48.8% males, age 62.3 ± 10.6 years; disease duration: 14 ± 4.4 years; median H & Y stage 3; interquartile range [IQR]: 3-4) and 44 on IJLI (56.8% males, age 62.7 ± 9.1 years; disease duration: 16.1 ± 6.7 years; median H & Y stage 4; IQR, 3-4). Cohen's effect sizes (≥0.8 considered as large) were "large" with both therapies with respect to total motor, nonmotor, and quality-of-life scores. The Non-Motor Symptoms Scale (NMSS) with Apo showed moderate improvement, whereas sleep/fatigue, gastrointestinal, urinary, and sexual dimensions of the NMSS showed significantly higher improvement with IJLI. Seventy-five percent on IJLI improved in their quality-of-life and nonmotor symptoms (NMS), whereas in the Apo group, a similar proportion improved in quality of life, but 40% in NMS. Adverse effects included peritonitis with IJLI and skin nodules on Apo. Based on this open-label, nonrandomized, comparative study, we report that, in advanced Parkinson's patients, both IJLI and Apo infusion therapy appear to provide a robust improvement in motor symptoms, motor complications, quality-of-life, and some NMS. Controlled, randomized studies are required.

  8. THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS

    SciTech Connect

    Federrath, Christoph; Klessen, Ralf S.

    2012-12-20

    The role of turbulence and magnetic fields is studied for star formation in molecular clouds. We derive and compare six theoretical models for the star formation rate (SFR)-the Krumholz and McKee (KM), Padoan and Nordlund (PN), and Hennebelle and Chabrier (HC) models, and three multi-freefall versions of these, suggested by HC-all based on integrals over the log-normal distribution of turbulent gas. We extend all theories to include magnetic fields and show that the SFR depends on four basic parameters: (1) virial parameter {alpha}{sub vir}; (2) sonic Mach number M; (3) turbulent forcing parameter b, which is a measure for the fraction of energy driven in compressive modes; and (4) plasma {beta}=2M{sub A}{sup 2}/M{sup 2} with the Alfven Mach number M{sub A}. We compare all six theories with MHD simulations, covering cloud masses of 300 to 4 Multiplication-Sign 10{sup 6} M{sub Sun} and Mach numbers M=3-50 and M{sub A}=1-{infinity}, with solenoidal (b = 1/3), mixed (b = 0.4), and compressive turbulent (b = 1) forcings. We find that the SFR increases by a factor of four between M=5 and 50 for compressive turbulent forcing and {alpha}{sub vir} {approx} 1. Comparing forcing parameters, we see that the SFR is more than 10 times higher with compressive than solenoidal forcing for M=10 simulations. The SFR and fragmentation are both reduced by a factor of two in strongly magnetized, trans-Alfvenic turbulence compared to hydrodynamic turbulence. All simulations are fit simultaneously by the multi-freefall KM and multi-freefall PN theories within a factor of two over two orders of magnitude in SFR. The simulated SFRs cover the range and correlation of SFR column density with gas column density observed in Galactic clouds, and agree well for star formation efficiencies SFE = 1%-10% and local efficiencies {epsilon} = 0.3-0.7 due to feedback. We conclude that the SFR is primarily controlled by interstellar turbulence, with a secondary effect coming from magnetic fields.

  9. The Star Formation Rate of Turbulent Magnetized Clouds: Comparing Theory, Simulations, and Observations

    NASA Astrophysics Data System (ADS)

    Federrath, Christoph; Klessen, Ralf S.

    2012-12-01

    The role of turbulence and magnetic fields is studied for star formation in molecular clouds. We derive and compare six theoretical models for the star formation rate (SFR)—the Krumholz & McKee (KM), Padoan & Nordlund (PN), and Hennebelle & Chabrier (HC) models, and three multi-freefall versions of these, suggested by HC—all based on integrals over the log-normal distribution of turbulent gas. We extend all theories to include magnetic fields and show that the SFR depends on four basic parameters: (1) virial parameter αvir (2) sonic Mach number {M}; (3) turbulent forcing parameter b, which is a measure for the fraction of energy driven in compressive modes; and (4) plasma \\beta =2 {M}_A^2/ {M}^2 with the Alfvén Mach number {M}_A. We compare all six theories with MHD simulations, covering cloud masses of 300 to 4 × 106 M ⊙ and Mach numbers {M}=3-50 and {M}_A=1-∞, with solenoidal (b = 1/3), mixed (b = 0.4), and compressive turbulent (b = 1) forcings. We find that the SFR increases by a factor of four between {M}=5 and 50 for compressive turbulent forcing and αvir ~ 1. Comparing forcing parameters, we see that the SFR is more than 10 times higher with compressive than solenoidal forcing for {M}=10 simulations. The SFR and fragmentation are both reduced by a factor of two in strongly magnetized, trans-Alfvénic turbulence compared to hydrodynamic turbulence. All simulations are fit simultaneously by the multi-freefall KM and multi-freefall PN theories within a factor of two over two orders of magnitude in SFR. The simulated SFRs cover the range and correlation of SFR column density with gas column density observed in Galactic clouds, and agree well for star formation efficiencies SFE = 1%-10% and local efficiencies epsilon = 0.3-0.7 due to feedback. We conclude that the SFR is primarily controlled by interstellar turbulence, with a secondary effect coming from magnetic fields.

  10. Automated diagnosis of interstitial lung diseases and emphysema in MDCT imaging

    NASA Astrophysics Data System (ADS)

    Fetita, Catalin; Chang Chien, Kuang-Che; Brillet, Pierre-Yves; Prêteux, Françoise

    2007-09-01

    Diffuse lung diseases (DLD) include a heterogeneous group of non-neoplasic disease resulting from damage to the lung parenchyma by varying patterns of inflammation. Characterization and quantification of DLD severity using MDCT, mainly in interstitial lung diseases and emphysema, is an important issue in clinical research for the evaluation of new therapies. This paper develops a 3D automated approach for detection and diagnosis of diffuse lung diseases such as fibrosis/honeycombing, ground glass and emphysema. The proposed methodology combines multi-resolution 3D morphological filtering (exploiting the sup-constrained connection cost operator) and graph-based classification for a full characterization of the parenchymal tissue. The morphological filtering performs a multi-level segmentation of the low- and medium-attenuated lung regions as well as their classification with respect to a granularity criterion (multi-resolution analysis). The original intensity range of the CT data volume is thus reduced in the segmented data to a number of levels equal to the resolution depth used (generally ten levels). The specificity of such morphological filtering is to extract tissue patterns locally contrasting with their neighborhood and of size inferior to the resolution depth, while preserving their original shape. A multi-valued hierarchical graph describing the segmentation result is built-up according to the resolution level and the adjacency of the different segmented components. The graph nodes are then enriched with the textural information carried out by their associated components. A graph analysis-reorganization based on the nodes attributes delivers the final classification of the lung parenchyma in normal and ILD/emphysematous regions. It also makes possible to discriminate between different types, or development stages, among the same class of diseases.

  11. Comparing and contrasting observed adaptations in three deltas: the Ganges-Meghna-Brahmaputra, Mahanadi and Volta

    NASA Astrophysics Data System (ADS)

    Nicholls, R. J.; Suckall, N.; Mensah, A.; Mondal, S.; Dey, S.; Hazra, S.

    2015-12-01

    In low and middle-income countries, many deltaic communities directly depend on the natural environment for income and well-being. Current environmental concerns that threaten deltaic communities, such as increasing salinity, sedimentation, erosion and subsidence are likely to be exacerbated by climate change and variability, for example sea-level rise, increased storminess and rising temperatures. Such changes, along with other social and environmental stressors, mean that communities must adapt. This paper outlines findings of a systematic review of the peer-reviewed and grey literature that examines observed adaptations in three deltas of differing sizes in various geographical contexts: the Ganges-Meghna-Brahmaputra in India and Bangladesh, the Mahanadi in India, and the Volta in Ghana. It compares and contrasts various elements of observed adaptations, including who is driving the adaptation, the beneficiaries, barriers to participation and evidence for maladaptation. The predominant drivers of adaptation vary from government (at state level in India and national level in Bangladesh) and NGOs (in Ghana). Autonomous adaptations are not widely reported in the literature from any of the deltas. In all three deltas there is a focus on supporting adaptation in farming rather than fishing; despite the fact that fisheries contribute to local food security as well as national economies. Lack of access to financial, natural, physical and human capital are common barriers to adaptation in all three deltas. Additionally the Indian literature in particular highlights the lack of coordination between different government departments, coupled with an excessively top-down (state-driven) approach to adaptation. Maladaptation is most commonly reported in the literature from Bangladesh, for example, loss of employment of inland fishermen in embanked areas. The paper concludes by highlighting some of the implications of these findings for adaptation policy in deltas.

  12. Comparing the relationships between aerosol optical depth and cloud properties in observations and global models

    NASA Astrophysics Data System (ADS)

    Gryspeerdt, Edward; Quaas, Johannes

    2016-04-01

    Aerosols impact the climate both directly, through their interaction with radiation and indirectly, via their ability to act as cloud condensation nuclei (CCN), modifying cloud properties. The influence of aerosols on cloud properties is highly uncertain. Many relationships between aerosol optical depth (AOD) and cloud properties have been observed using satellite data, but previous work has shown that some of these relationships are the product of the strong AOD-cloud fraction (CF) relationship. The confounding influence of local meteorology obscures the magnitude of any aerosol impact on CF, and so also the impact of aerosol on other cloud properties. For example, both AOD and CF are strongly influenced by relative humidity, which can generate a correlation between them. Previous studies have used reanalysis data to account for confounding meteorological variables. This requires knowledge of the relevant meteorological variables and is limited by the accuracy of the reanalysis data. Recent work has shown that by using the cloud droplet number concentration (CDNC) to mediate the AOD-CF relationship, the impact of relative humidity can be significantly reduced. This method removes the limitations imposed by the finite accuracy of reanalysis data. In this work we investigate the impact of the CDNC mediation on the AOD-CF relationship and on the relationship between AOD and other cloud properties in global atmospheric models. By comparing pre-industrial and present day runs, we investigate the success of the CDNC mediated AOD-CF relationship to predict the change in CF from the pre-industrial to the present day using only observations of the present day relationships between clouds and aerosol properties. This helps to determine whether the satellite-derived relationship provides a constraint on the aerosol indirect forcing due to changes in CF.

  13. A Proxy System Modeling Toolbox for Comparing Water Isotope Observations to Simulations

    NASA Astrophysics Data System (ADS)

    Dee, S. G.; Emile-Geay, J.; Evans, M. N.; Noone, D. C.

    2014-12-01

    Simulations which integrate both climate physics and the processes by which climate variations are imprinted in and sampled from paleoclimate archives may facilitate differentiation of the climate signal from random and systematic sources of uncertainty. We simulate the former using a newly developed efficient water-isotope-enabled atmospheric GCM, SPEEDY-IER (Molteni, 2003, Dee et al., submitted), and the latter using a toolbox of proxy system models (PSMs, Evans et al., 2013), synthesized, organized and coded within a self-consistent framework (Dee et al., in prep). SPEEDY-IER is forced with SSTs from the Last Millennium PMIP3 integration of the CCSM4 model (Landrum et al., 2012); relevant climate and isotope variables are extracted from the GCM simulation and used to drive PSMs. Through comparing simulated climate fields to simulated observations, we evaluate the extent to which linear and univariate calibrations on local temperature are valid, given bias in the simulated SST, moisture divergence, and associated isotopic composition of water vapor and precipitation. Taking this a step further, PSMs that incorporate the physical, biological, structural, and time-uncertain aspects of each proxy system help to explicitly quantify the errors accompanying the assumption of linear univariate response of proxy systems to climate forcing. We demonstrate the utility of the PSM toolbox with an integrative multi-PSM simulation spanning a realistic pan-tropical pacific proxy network of tree-ring cellulose, speleothem, and ice core oxygen isotopic composition (δ18O). The multi-PSM simulation is used as a testing ground to assess the robustness of frequently invoked teleconnections relating tropical SSTs to terrestrial hydroclimate proxies. By exploring modeled connections between ocean climate and the proxies (both by individual proxy class and for the entire network), we identify which tropical SST signals can be captured by the proxy network, track the individual

  14. The most characteristic lesions and radiologic signs of Crohn disease of the small bowel: air enteroclysis, MDCT, endoscopy, and pathology.

    PubMed

    Carbo, Alberto I; Reddy, Threta; Gates, Thomas; Vesa, Telciane; Thomas, Jaiyeola; Gonzalez, Enrique

    2014-02-01

    This pictorial essay describes the most characteristic lesions and radiologic signs of Crohn disease of the small bowel: nodular lymphoid hyperplasia, abnormal mucosal folds, villous pattern, aphthous ulcerations, linear ulcerations, cobblestone pattern, string sign, target sign, comb sign, creeping fat, sinus tracts, fistulas, and abscesses. Each description includes the definition, a correlation with the pathologic findings, an explanation of the possible physiopathologic mechanism, sample radiologic images with air enteroclysis or MDCT, the correspondence with the endoscopic findings when possible, and a list of differential diagnoses.

  15. Comparative incidence of pregnancy outcomes in treated obstetric antiphospholipid syndrome: the NOH-APS observational study.

    PubMed

    Bouvier, Sylvie; Cochery-Nouvellon, Eva; Lavigne-Lissalde, Géraldine; Mercier, Erick; Marchetti, Tess; Balducchi, Jean-Pierre; Marès, Pierre; Gris, Jean-Christophe

    2014-01-16

    The incidence of pregnancy outcomes for women with the purely obstetric form of antiphospholipid syndrome (APS) treated with prophylactic low-molecular-weight heparin (LMWH) plus low-dose aspirin (LDA) has not been documented. We observed women without a history of thrombosis who had experienced 3 consecutive spontaneous abortions before the 10th week of gestation or 1 fetal loss at or beyond the 10th week. We compared the frequencies of complications during new pregnancies between treated women with APS (n = 513; LMWH + LDA) and women negative for antiphospholipid antibodies as controls (n = 791; no treatment). Among APS women, prior fetal loss was a risk factor for fetal loss, preeclampsia (PE), premature birth, and the occurrence of any placenta-mediated complication. Being positive for anticardiolipin immunoglobulin M antibodies was a risk factor for any placenta-mediated complication. Among women with a history of recurrent abortion, APS women were at a higher risk than other women of PE, placenta-mediated complications, and neonatal mortality. Among women with prior fetal loss, LMWH + LDA-treated APS women had lower pregnancy loss rates but higher PE rates than other women. Improved therapies, in particular better prophylaxis of late pregnancy complications, are urgently needed for obstetric APS and should be evaluated according to the type of pregnancy loss.

  16. A Field Guide to Extra-Tropical Cyclones: Comparing Models to Observations

    NASA Astrophysics Data System (ADS)

    Bauer, M.

    2008-12-01

    Climate it is said is the accumulation of weather. And weather is not the concern of climate models. Justification for this latter sentiment has long hidden behind coarse model resolutions and blunt validation tools based on climatological maps and the like. The spatial-temporal resolutions of today's models and observations are converging onto meteorological scales however, which means that with the correct tools we can test the largely unproven assumption that climate model weather is correct enough, or at least lacks perverting biases, such that its accumulation does in fact result in a robust climate prediction. Towards this effort we introduce a new tool for extracting detailed cyclone statistics from climate model output. These include the usual cyclone distribution statistics (maps, histograms), but also adaptive cyclone- centric composites. We have also created a complementary dataset, The MAP Climatology of Mid-latitude Storminess (MCMS), which provides a detailed 6 hourly assessment of the areas under the influence of mid- latitude cyclones based on Reanalysis products. Using this we then extract complimentary composites from sources such as ISCCP and GPCP to create a large comparative dataset for climate model validation. A demonstration of the potential usefulness of these tools will be shown. dime.giss.nasa.gov/mcms/mcms.html

  17. Synchronous infection of the aorta and the testis: emphysematous epididymo-orchitis, abdominal aortic mycotic aneurysm, and testicular artery pseudoaneurysm diagnosed by use of MDCT.

    PubMed

    Hegde, Rahul G; Balani, Ankit; Merchant, Suleman A; Joshi, Anagha R

    2014-07-01

    We report clinical details and imaging findings for a case of emphysematous epididymo-orchitis with co-existing mycotic abdominal aortic aneurysm and a testicular artery pseudoaneurysm in a diabetic 65-year-old male. We report imaging findings from ultrasonography (USG) and contrast-enhanced multidetector computed tomography (MDCT). Use of MDCT to identify, confirm, and define the extent of the disease, and its utility in understanding the pathogenesis of this rare condition are highlighted. For such lethal infections, early diagnosis and intervention can be lifesaving; imaging can be of crucial importance in this.

  18. Three-dimensional simulations of gravitationally confined detonations compared to observations of SN 1991T

    NASA Astrophysics Data System (ADS)

    Seitenzahl, Ivo R.; Kromer, Markus; Ohlmann, Sebastian T.; Ciaraldi-Schoolmann, Franco; Marquardt, Kai; Fink, Michael; Hillebrandt, Wolfgang; Pakmor, Rüdiger; Röpke, Friedrich K.; Ruiter, Ashley J.; Sim, Stuart A.; Taubenberger, Stefan

    2016-07-01

    The gravitationally confined detonation (GCD) model has been proposed as a possible explosion mechanism for Type Ia supernovae in the single-degenerate evolution channel. It starts with ignition of a deflagration in a single off-centre bubble in a near-Chandrasekhar-mass white dwarf. Driven by buoyancy, the deflagration flame rises in a narrow cone towards the surface. For the most part, the main component of the flow of the expanding ashes remains radial, but upon reaching the outer, low-pressure layers of the white dwarf, an additional lateral component develops. This causes the deflagration ashes to converge again at the opposite side, where the compression heats fuel and a detonation may be launched. We first performed five three-dimensional hydrodynamic simulations of the deflagration phase in 1.4 M⊙ carbon/oxygen white dwarfs at intermediate-resolution (2563 computational zones). We confirm that the closer the initial deflagration is ignited to the centre, the slower the buoyant rise and the longer the deflagration ashes takes to break out and close in on the opposite pole to collide. To test the GCD explosion model, we then performed a high-resolution (5123 computational zones) simulation for a model with an ignition spot offset near the upper limit of what is still justifiable, 200 km. This high-resolution simulation met our deliberately optimistic detonation criteria, and we initiated a detonation. The detonation burned through the white dwarf and led to its complete disruption. For this model, we determined detailed nucleosynthetic yields by post-processing 106 tracer particles with a 384 nuclide reaction network, and we present multi-band light curves and time-dependent optical spectra. We find that our synthetic observables show a prominent viewing-angle sensitivity in ultraviolet and blue wavelength bands, which contradicts observed SNe Ia. The strong dependence on the viewing angle is caused by the asymmetric distribution of the deflagration ashes

  19. CFD Simulations of Supersonic Highly Swirling Flow Exiting a Turbine Vane Row Compared with Experimental Observations

    NASA Technical Reports Server (NTRS)

    West, Jeff S.; Richardson, Brian R.; Schmauch, Preston; Kenny, Robert J.

    2011-01-01

    Marshall Space Flight Center (MSFC) has been heavily involved in developing the J2-X engine. The Center has been testing a Work Horse Gas Generator (WHGG) to supply gas products to J2-X turbine components at realistic flight-like operating conditions. Three-dimensional time accurate CFD simulations and analytical fluid analysis have been performed to support WHGG tests at MSFC. The general purpose CFD program LOCI/Chem was utilized to simulate flow of products from the WHGG through a turbine manifold, a stationary row of turbine vanes, into a Can and orifice assembly used to control the back pressure at the turbine vane row and finally through an aspirator plate and flame bucket. Simulations showed that supersonic swirling flow downstream of the turbine imparted a much higher pressure on the Can wall than expected for a non-swirling flow. This result was verified by developing an analytical model that predicts wall pressure due to swirling flow. The CFD simulations predicted that the higher downstream pressure would cause the pressure drop across the nozzle row to be approximately half the value of the test objective. With CFD support, a redesign of the Can orifice and aspirator plate was performed. WHGG experimental results and observations compared well with pre-test and post-test CFD simulations. CFD simulations for both quasi-static and transient test conditions correctly predicted the pressure environment downstream of the turbine row and the behavior of the gas generator product plume as it exited the WHGG test article, impacted the flame bucket and interacted with the external environment.

  20. Determination of dark energy by the Einstein Telescope: Comparing with CMB, BAO, and SNIa observations

    NASA Astrophysics Data System (ADS)

    Zhao, W.; van den Broeck, C.; Baskaran, D.; Li, T. G. F.

    2011-01-01

    A design study is currently in progress for a third-generation gravitational-wave (GW) detector called the Einstein Telescope (ET). An important kind of source for ET will be the inspiral and merger of binary neutron stars up to z˜2. If binary neutron star mergers are the progenitors of short-hard γ-ray bursts, then some fraction of them will be seen both electromagnetically and through GW, so that the luminosity distance and the redshift of the source can be determined separately. An important property of these “standard sirens” is that they are self-calibrating: the luminosity distance can be inferred directly from the GW signal, with no need for a cosmic distance ladder. Thus, standard sirens will provide a powerful independent check of the ΛCDM model. In previous work, estimates were made of how well ET would be able to measure a subset of the cosmological parameters (such as the dark energy parameter w0) it will have access to, assuming that the others had been determined to great accuracy by alternative means. Here we perform a more careful analysis by explicitly using the potential Planck cosmic microwave background data as prior information for these other parameters. We find that ET will be able to constrain w0 and wa with accuracies Δw0=0.099 and Δwa=0.302, respectively. These results are compared with projected accuracies for the JDEM baryon acoustic oscillations project and the SNAP type Ia supernovae observations.

  1. Determination of dark energy by the Einstein Telescope: Comparing with CMB, BAO, and SNIa observations

    SciTech Connect

    Zhao, W.; Baskaran, D.; Van Den Broeck, C.; Li, T. G. F.

    2011-01-15

    A design study is currently in progress for a third-generation gravitational-wave (GW) detector called the Einstein Telescope (ET). An important kind of source for ET will be the inspiral and merger of binary neutron stars up to z{approx}2. If binary neutron star mergers are the progenitors of short-hard {gamma}-ray bursts, then some fraction of them will be seen both electromagnetically and through GW, so that the luminosity distance and the redshift of the source can be determined separately. An important property of these 'standard sirens' is that they are self-calibrating: the luminosity distance can be inferred directly from the GW signal, with no need for a cosmic distance ladder. Thus, standard sirens will provide a powerful independent check of the {Lambda}CDM model. In previous work, estimates were made of how well ET would be able to measure a subset of the cosmological parameters (such as the dark energy parameter w{sub 0}) it will have access to, assuming that the others had been determined to great accuracy by alternative means. Here we perform a more careful analysis by explicitly using the potential Planck cosmic microwave background data as prior information for these other parameters. We find that ET will be able to constrain w{sub 0} and w{sub a} with accuracies {Delta}w{sub 0}=0.099 and {Delta}w{sub a}=0.302, respectively. These results are compared with projected accuracies for the JDEM baryon acoustic oscillations project and the SNAP type Ia supernovae observations.

  2. Filtering and Gridding Satellite Observations of Cloud Variables to Compare with Climate Model Output

    NASA Astrophysics Data System (ADS)

    Pitts, K.; Nasiri, S. L.; Smith, N.

    2013-12-01

    Global climate models have improved considerably over the years, yet clouds still represent a large factor of uncertainty for these models. Comparisons of model-simulated cloud variables with equivalent satellite cloud products are the best way to start diagnosing the differences between model output and observations. Gridded (level 3) cloud products from many different satellites and instruments are required for a full analysis, but these products are created by different science teams using different algorithms and filtering criteria to create similar, but not directly comparable, cloud products. This study makes use of a recently developed uniform space-time gridding algorithm to create a new set of gridded cloud products from each satellite instrument's level 2 data of interest which are each filtered using the same criteria, allowing for a more direct comparison between satellite products. The filtering is done via several variables such as cloud top pressure/height, thermodynamic phase, optical properties, satellite viewing angle, and sun zenith angle. The filtering criteria are determined based on the variable being analyzed and the science question at hand. Each comparison of different variables may require different filtering strategies as no single approach is appropriate for all problems. Beyond inter-satellite data comparison, these new sets of uniformly gridded satellite products can also be used for comparison with model-simulated cloud variables. Of particular interest to this study are the differences in the vertical distributions of ice and liquid water content between the satellite retrievals and model simulations, especially in the mid-troposphere where there are mixed-phase clouds to consider. This presentation will demonstrate the proof of concept through comparisons of cloud water path from Aqua MODIS retrievals and NASA GISS-E2-[R/H] model simulations archived in the CMIP5 data portal.

  3. MDCT Anatomic Assessment of Right Inferior Phrenic Artery Origin Related to Potential Supply to Hepatocellular Carcinoma and its Embolization

    SciTech Connect

    Basile, Antonio Tsetis, Dimitrios; Montineri, Arturo; Puleo, Stefano; Massa Saluzzo, Cesare; Runza, Giuseppe; Coppolino, Francesco; Ettorre, Giovanni Carlo; Patti, Maria Teresa

    2008-03-15

    Purpose. To prospectively assess the anatomic variation of the right inferior phrenic artery (RIPA) origin with multidetector computed tomography (MDCT) scans in relation to the technical and angiographic findings during transcatheter arterial embolization of hepatocellular carcinoma (HCC). Methods. Two hundred patients with hepatocellular carcinomas were examined with 16-section CT during the arterial phase. The anatomy of the inferior phrenic arteries was recorded, with particular reference to their origin. All patients with subcapsular HCC located at segments VII and VIII underwent arteriography of the RIPA with subsequent embolization if neoplastic supply was detected. Results. The RIPA origin was detected in all cases (sensitivity 100%), while the left inferior phrenic artery origin was detected in 187 cases (sensitivity 93.5%). RIPAs originated from the aorta (49%), celiac trunk (41%), right renal artery (5.5%), left gastric artery (4%), and proper hepatic artery (0.5%), with 13 types of combinations with the left IPA. Twenty-nine patients showed subcapsular HCCs in segments VII and VIII and all but one underwent RIPA selective angiography, followed by embolization in 7 cases. Conclusion. MDCT assesses well the anatomy of RIPAs, which is fundamental for planning subsequent cannulation and embolization of extrahepatic RIPA supply to HCC.

  4. The impacts of open-mouth breathing on upper airway space in obstructive sleep apnea: 3-D MDCT analysis.

    PubMed

    Kim, Eun Joong; Choi, Ji Ho; Kim, Kang Woo; Kim, Tae Hoon; Lee, Sang Hag; Lee, Heung Man; Shin, Chol; Lee, Ki Yeol; Lee, Seung Hoon

    2011-04-01

    Open-mouth breathing during sleep is a risk factor for obstructive sleep apnea (OSA) and is associated with increased disease severity and upper airway collapsibility. The aim of this study was to investigate the effect of open-mouth breathing on the upper airway space in patients with OSA using three-dimensional multi-detector computed tomography (3-D MDCT). The study design included a case-control study with planned data collection. The study was performed at a tertiary medical center. 3-D MDCT analysis was conducted on 52 patients with OSA under two experimental conditions: mouth closed and mouth open. Under these conditions, we measured the minimal cross-sectional area of the retropalatal and retroglossal regions (mXSA-RP, mXSA-RG), as well as the upper airway length (UAL), defined as the vertical dimension from hard palate to hyoid. We also computed the volume of the upper airway space by 3-D reconstruction of both conditions. When the mouth was open, mXSA-RP and mXSA-RG significantly decreased and the UAL significantly increased, irrespective of the severity of OSA. However, between the closed- and open-mouth states, there was no significant change in upper airway volume at any severity of OSA. Results suggest that the more elongated and narrow upper airway during open-mouth breathing may aggravate the collapsibility of the upper airway and, thus, negatively affect OSA severity.

  5. Development of density plumes of dissolved CO2: Comparing experimental observations with numerical simulations

    NASA Astrophysics Data System (ADS)

    Kirk, Karen; Vosper, Hayley; Rochelle, Chris; Noy, Dave; Chadwick, Andy

    2014-05-01

    The long-term trapping of CO2 within deep geological storage reservoirs will be dependent upon CO2-water-rock geochemical reactions. The first, and most important, steps in this process will be dissolution of CO2 into the reservoir porewater and the transport of this dissolved CO2 through the reservoir. As part of the CO2CARE project we have investigated these via laboratory tests using a water-filled porous medium. Key experimental parameters were measured to determine system permeability, so that a high-resolution numerical model could be built in an attempt to reproduce the observed system behaviour. The Hele-Shaw cell comprised two glass sheets 65 cm wide and 36 cm high, separated by a spacing of 1.1 mm, and filled with closely-packed glass beads 0.4-0.6 mm in diameter. The surface of the glass was treated to prevent the formation of a higher permeability zone along this interface. A pH-sensitive dye was added to the pore-filling water to show where it had been acidified due to the presence of CO2. CO2 gas was introduced to a space at the top of the cell, which created a thin, diffusion-controlled boundary layer of CO2-rich water below the CO2-water interface. CO2 dissolution increased water density, resulting in gravitational instabilities and the formation of many small, downward-migrating plumes. Time-lapse photography was used to track the formation and progress of these plumes. As the plumes grew they increased in length relative to their width, and decreased in number over time. They also became more complex with time, splitting and forming several lobes, whose outer edges became more diffuse as they mixed with the CO2-poor water. The onset time of plume development and the horizontal wavelength (spacing) of the descending plumes are diagnostic measures of the system properties, notably permeability. They were analysed from the time-lapse images and expressed as probability density functions based on histograms of the observations. The derived

  6. Comparative analysis of decametre "drift pair" bursts observed in 2002 and 2015

    NASA Astrophysics Data System (ADS)

    Volvach, Ya. S.; Stanislavsky, A. A.; Konovalenko, A. A.; Koval, A. A.; Dorovskyy, V. V.

    2016-09-01

    We report about new observations of solar "drift pair" (DP) bursts by means of the UTR-2 radio telescope at frequencies 10-30 MHz. Our experimental data include both "forward" and "reverse" bursts with high frequency and time resolution. The records of 301 bursts, observed in 10-12 July of 2015, are investigated. The main properties of these bursts (frequency bandwidth, central frequency and others) have been analysed. In this report our main attention is paid to the comparison of our observations with the similar observations of decametre DPs performed earlier during 13-15 July of 2002 in the same frequency range. Common features of DPs in the two different pieces of data samples have been found. This may indicate the possible presence of stability in the frequency-time properties of decametre DPs from one cycle of solar activity to another.

  7. Comparative study of aerosols observed by YAG lidar and airborne detectors

    NASA Technical Reports Server (NTRS)

    Hirono, M.; Fujiwara, M.; Shibata, T.

    1985-01-01

    The causal relationships of very large (tropical) volcanic eruptions and El Nino Southern Oscillations (ENSO) based on the unequal atmospheric heating by aerosols observed by lidar and airborne detectors are discussed.

  8. Validity of the modified RULA for computer workers and reliability of one observation compared to six.

    PubMed

    Levanon, Yafa; Lerman, Yehuda; Gefen, Amit; Ratzon, Navah Z

    2014-01-01

    Awkward body posture while typing is associated with musculoskeletal disorders (MSDs). Valid rapid assessment of computer workers' body posture is essential for the prevention of MSD among this large population. This study aimed to examine the validity of the modified rapid upper limb assessment (mRULA) which adjusted the rapid upper limb assessment (RULA) for computer workers. Moreover, this study examines whether one observation during a working day is sufficient or more observations are needed. A total of 29 right-handed computer workers were recruited. RULA and mRULA were conducted. The observations were then repeated six times at one-hour intervals. A significant moderate correlation (r = 0.6 and r = 0.7 for mouse and keyboard, respectively) was found between the assessments. No significant differences were found between one observation and six observations per working day. The mRULA was found to be valid for the assessment of computer workers, and one observation was sufficient to assess the work-related risk factor.

  9. Interprofessional primary care team meetings: a qualitative approach comparing observations with personal opinions

    PubMed Central

    van Dongen, Jerôme Jean Jacques; van Bokhoven, Marloes Amantia; Daniëls, Ramon; Lenzen, Stephanie Anna; van der Weijden, Trudy; Beurskens, Anna

    2017-01-01

    Background. The number of people with multiple chronic conditions requiring primary care services increases. Professionals from different disciplines collaborate and coordinate care to deal with the complex health care needs. There is lack of information on current practices regarding interprofessional team (IPT) meetings. Objectives. This study aimed to improve our understanding of the process of interprofessional collaboration in primary care team meetings in the Netherlands by observing the current practice and exploring personal opinions. Methods. Qualitative study involving observations of team meetings and interviews with participants. Eight different IPT meetings (n = 8) in different primary care practices were observed by means of video recordings. Experiences were explored by conducting individual semi-structured interviews (n = 60) with participants (i.e. health care professionals from different disciplines) of the observed team meetings. The data were analysed by means of content analysis. Results. Most participants expressed favourable opinions about their team meetings. However, observations showed that team meetings were more or less hectic, and lacked a clear structure and team coordinator or leader. There appears to be a discrepancy between findings from observations and interviews. From the interviews, four main themes were extracted: (1) Team structure and composition, (2) Patient-centredness, (3) Interaction and (4) Attitude and motivation. Conclusion. IPT meetings could benefit from improvements in structure, patient-centredness and leadership by the chairpersons. Given the discrepancy between observations and interviews, it would appear useful to improve team members’ awareness of aspects that could be improved before training them in dealing with specific challenges. PMID:28122925

  10. Using data assimilation to compare models of Mars and Venus atmospheres with observations

    NASA Astrophysics Data System (ADS)

    Navarro, Thomas; Forget, Francois; Millour, Ehouarn

    2016-10-01

    Data assimilation is a technique that optimally reconstructs a best estimate of the atmospheric state by combining observations and an a priori provided by a numerical model. The aim of data assimilation is to extrapolate in space and time observations of the atmosphere with the means of a model in order to recover the state of the atmosphere as completely and as accurately as possible.In this work, we employ a state-of-the-art Martian Global Climate Model to assimilate vertical profiles of atmospheric temperature, airborne dust, and water ice clouds retrieved from observations of the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter. The assimilation is carried out using an Ensemble Kalman Filter technique, that maps covariances between model variables. Therefore, observations of one variable (e.g. temperature) can be used to estimate other unobserved variables (e.g. winds), using covariances constructed from an ensemble of model simulations for which initial states slightly differ. Using this method, one can estimate dust from temperature observations only, confirming the presence of detached layers of dust in the atmosphere from their thermal signature. Then, the joint assimilation of temperature, dust, and water ice clouds shows that the performance of the assimilation is limited due to model biases, such as an incorrect phasing of the thermal tide and observed dust diurnal variations unexplained by a model. However, dust estimation makes possible the predictability of the atmosphere, up to around ten days in the most favorable cases, a great improvement over previous studies.Future developments for an improved assimilation strongly suggest to assimilate model parameters, such as the ones for the representation of parameterized atmospheric gravity waves.Also, in the light of the recent global observations of the Venusian atmosphere from the Akastuki spacecraft, the case for the first-ever assimilation of Venus will be made.

  11. Bias in Observational Studies of Prevalent Users: Lessons for Comparative Effectiveness Research From a Meta-Analysis of Statins

    PubMed Central

    Danaei, Goodarz; Tavakkoli, Mohammad; Hernán, Miguel A.

    2012-01-01

    Randomized clinical trials (RCTs) are usually the preferred strategy with which to generate evidence of comparative effectiveness, but conducting an RCT is not always feasible. Though observational studies and RCTs often provide comparable estimates, the questioning of observational analyses has recently intensified because of randomized-observational discrepancies regarding the effect of postmenopausal hormone replacement therapy on coronary heart disease. Reanalyses of observational data that excluded prevalent users of hormone replacement therapy led to attenuated discrepancies, which begs the question of whether exclusion of prevalent users should be generally recommended. In the current study, the authors evaluated the effect of excluding prevalent users of statins in a meta-analysis of observational studies of persons with cardiovascular disease. The pooled, multivariate-adjusted mortality hazard ratio for statin use was 0.77 (95% confidence interval (CI): 0.65, 0.91) in 4 studies that compared incident users with nonusers, 0.70 (95% CI: 0.64, 0.78) in 13 studies that compared a combination of prevalent and incident users with nonusers, and 0.54 (95% CI: 0.45, 0.66) in 13 studies that compared prevalent users with nonusers. The corresponding hazard ratio from 18 RCTs was 0.84 (95% CI: 0.77, 0.91). It appears that the greater the proportion of prevalent statin users in observational studies, the larger the discrepancy between observational and randomized estimates. PMID:22223710

  12. Comparative studies on polar ionosphere and magnetotail dynamics based on simultaneous multi-point observations

    NASA Astrophysics Data System (ADS)

    Fukuda, Yoko; Hirahara, Masafumi; Sakanoi, Takeshi; Ebihara, Yusuke; Asamura, Kazushi; Yamazaki, Atsushi; Seki, Kanako; Miyashita, Yukinaga

    For observations of the nightside polar ionosphere, the Reimei satellite is capable of simultane-ous observations for auroral 2D distribution by Multi-spectral Aurora Imaging Camera (MAC) and auroral particles by Electron/Ion Energy Spectrum Analyzer (ESA/ISA). Reimei has been observing the auroral fine structures at altitudes of about 640km by the unprecedented high spatial and temporal resolutions and promoting the understanding of the their fine structures. On the other hand, the field-aligned electric field and Alfven waves have been investigated in the auroral acceleration region by using data of FAST, Polar, Akebono and the other satel-lites. The phenomena in this region are thought to be due to the fluctuation of plasma and electromagnetic field in the magnetotail. In addition to the auroral observations of the polar ionosphere, the data comparison between in the magnetotail and in the polar ionosphere will give us more comprehensive understandings of the auroral phenomena. For observations of the magnetotail, we use data by THEMIS satellites consisting of 5 probes. The simultaneous multipoint observations by these satellites are useful for the distinction between temporal vari-ation and spatial distribution. THEMIS-GBOs(Ground-based observatories) which are located on the Northern America also enable us to observe global aurora. In this presentation, in the dataset for 1.5-years interval possibly providing the simultaneous observations by Reimei and THEMIS, we focus on the data obtained on Feb. 9, 2008. When Reimei passed over Canada(70ILAT) from poleward to equatorward, the Inverted-V precipitating electrons signa-tures lasted about 13 seconds corresponding to 0.7 ILAT width, and the characteristic electron energy was 1-5keV according to the ESA measurement. Near the poleward edge observed for three seconds, a south-eastward flow and a folded arc were observed and then stable and faint aurora was observed according to the MAC. These two types of auroras

  13. Comparing regional modeling (CHIMERE) and satellite observations of aerosols (PARASOL): Methodology and case study over Mexico

    NASA Astrophysics Data System (ADS)

    Stromatas, Stavros

    2010-05-01

    S. Stromatas (1), S. Turquety (1), H. Chepfer (1), L. Menut (1), B. Bessagnet (2), JC Pere (2), D. Tanré (3) . (1) Laboratoire de Météorologie Dynamique, CNRS/IPSL, École Polytechnique, 91128 Palaiseau Cedex, France, (2) INERIS, Institut National de l'Environnement Industriel et des Risques, Parc technologique ALATA, 60550 Verneuil en Halatte, FRANCE, (3) Laboratoire d'Optique Atmosphérique/CNRS Univ. des Sciences et Tech. de Lille, 59650 - Villeneuve d'Ascq, France. Atmospheric suspended particles (aerosols) have significant radiative and environmental impacts, affecting human health, visibility and climate. Therefore, they are regulated by air quality standards worldwide, and monitored by regional observation networks. Satellite observations vastly improve the horizontal and temporal coverage, providing daily distributions. Aerosols are currently estimated using aerosol optical depth (AOD) retrievals, a quantitative measure of the extinction of solar radiation by aerosol scattering and absorption between the point of observation and the top of the atmosphere. Even though remarkable progresses in aerosol modeling by chemistry-transport models (CTM) and measurement experiments have been made in recent years, there is still a significant divergence between the modeled and observed results. However, AOD retrievals from satellites remains a highly challenging task mostly because it depends on a variety of different parameters such as cloud contamination, surface reflectance contributions and a priori assumptions on aerosol types, each one of them incorporating its own difficulties. Therefore, comparisons between CTM and observations are often difficult to interpret. In this presentation, we will discuss comparisons between regional modeling (CHIMERE CTM) over Mexico and satellite observations obtained by the POLDER instrument embarked on PARASOL micro-satellite. After a comparison of the model AOD with the retrieved L2 AOD, we will present an alternative

  14. Mental imagery of positive and neutral memories: A fMRI study comparing field perspective imagery to observer perspective imagery.

    PubMed

    Grol, Maud; Vingerhoets, Guy; De Raedt, Rudi

    2017-02-01

    Imagery perspective can influence what information is recalled, processing style, and emotionality; however, the understanding of possible mechanisms mediating these observed differences is still limited. We aimed to examine differences between memory recall from a field perspective and observer perspective at the neurobiological level, in order to improve our understanding of what is underlying the observed differences at the behavioral level. We conducted a fMRI study in healthy individuals, comparing imagery perspectives during recall of neutral and positive autobiographical memories. Behavioral results revealed field perspective imagery of positive memories, as compared to observer perspective, to be associated with more positive feelings afterwards. At the neurobiological level, contrasting observer perspective to field perspective imagery was associated with greater activity, or less decrease relative to the control visual search task, in the right precuneus and in the right temporoparietal junction (TPJ). Greater activity in the right TPJ during an observer perspective as compared to field perspective could reflect performing a greater shift of perspective and mental state during observer perspective imagery than field perspective imagery. Differential activity in the precuneus may reflect that during observer perspective imagery individuals are more likely to engage in (self-) evaluative processing and visuospatial processing. Our findings contribute to a growing understanding of how imagery perspective can influence the type of information that is recalled and the intensity of the emotional response. Observer perspective imagery may not automatically reduce emotional intensity but this could depend on how the imagined situation is evaluated in relation to the self-concept.

  15. Comparing Vignette Instruction and Assessment Tasks to Classroom Observations and Reflections

    ERIC Educational Resources Information Center

    Jeffries, Carolyn; Maeder, Dale W.

    2011-01-01

    The growing body of research on the use of vignettes in teacher education courses suggests that vignette-based instruction and assessment tasks may represent a viable alternative to traditional forms of scaffolded instruction and reflective essays following classroom observations, thereby creating a bridge between college and K-12 classrooms for…

  16. Comparative Analysis of Oscillations of a Solar Quiet Region Using Multi-Wavelength Observations

    NASA Astrophysics Data System (ADS)

    Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.

    2010-07-01

    We analyze the temporal behavior of a solar quiet region using a set of multi-wavelength observations obtained during a coordinated campaign. The observations were acquired by the ground-based Dutch Open Telescope (DOT), the Michelson Doppler Imager (MDI) on-board SOHO and the UV filters of the Transition Region and Coronal Explorer (TRACE). A large range of height in the solar atmosphere, from the deep photosphere to the upper chromosphere is covered by these instruments. We investigate the oscillation properties of the intensities and velocities in distinct regions of the quiet Sun, i.e. internetwork, bright points (NBP) defining the network boundaries and dark mottles forming a well-defined rosette, as observed by the different instruments and in the different heights. The variations of the intensities and velocities are studied with wavelet analysis. The aim of our work is to find similarities and/or differences in the oscillatory phenomena observed in the different examined regions, as well as comprehensive information on the interaction of the oscillations and the magnetic field.

  17. Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible un...

  18. Comparing Global Atmospheric CO2 Flux and Transport Models with Remote Sensing (and Other) Observations (Invited)

    NASA Astrophysics Data System (ADS)

    Kawa, S. R.; Collatz, G. J.; Pawson, S.; Wennberg, P. O.; Wofsy, S. C.; Andrews, A. E.

    2010-12-01

    We report recent progress derived from comparison of global CO2 flux and transport models with new remote sensing and other sources of CO2 data including those from satellite. The overall objective of this activity is to improve the process models that represent our understanding of the workings of the atmospheric carbon cycle. Model estimates of CO2 surface flux and atmospheric transport processes are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, to provide the basic framework for carbon data assimilation, and ultimately for future projections of carbon-climate interactions. Models can also be used to test consistency within and between CO2 data sets under varying geophysical states. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 2000 through 2009. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at 1x1 degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-3), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model’s ability to simulate CO2 flux and mixing ratio variability in comparison to remote sensing observations from TCCON, GOSAT, and AIRS as well as relevant in situ observations. Examples of the influence of key process representations are shown from both forward and inverse model comparisons. We find that the model can resolve much of the synoptic, seasonal, and interannual

  19. Comparing Global Atmospheric CO2 Flux and Transport Models with Remote Sensing (and Other) Observations

    NASA Technical Reports Server (NTRS)

    Kawa, S. R.; Collatz, G. J.; Pawson, S.; Wennberg, P. O.; Wofsy, S. C.; Andrews, A. E.

    2010-01-01

    We report recent progress derived from comparison of global CO2 flux and transport models with new remote sensing and other sources of CO2 data including those from satellite. The overall objective of this activity is to improve the process models that represent our understanding of the workings of the atmospheric carbon cycle. Model estimates of CO2 surface flux and atmospheric transport processes are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, to provide the basic framework for carbon data assimilation, and ultimately for future projections of carbon-climate interactions. Models can also be used to test consistency within and between CO2 data sets under varying geophysical states. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 2000 through 2009. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at 1x1 degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-3), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model's ability to simulate CO2 flux and mixing ratio variability in comparison to remote sensing observations from TCCON, GOSAT, and AIRS as well as relevant in situ observations. Examples of the influence of key process representations are shown from both forward and inverse model comparisons. We find that the model can resolve much of the synoptic, seasonal, and interannual

  20. Observing Political Systems: Political Systems, Unit One. Comparing Political Experiences, Experimental Materials.

    ERIC Educational Resources Information Center

    Gillespie, Judith A.; Patrick, John J.

    This first of three units of "Comparing Political Experiences", a first-semester course, provides 18 activities which introduce 12th-grade students to political system concepts that they will work with in-depth in succeeding units. The activities and readings, divided into seven sections, stress the development of political knowledge,…

  1. Observation

    ERIC Educational Resources Information Center

    Helfrich, Shannon

    2016-01-01

    Helfrich addresses two perspectives from which to think about observation in the classroom: that of the teacher observing her classroom, her group, and its needs, and that of the outside observer coming into the classroom. Offering advice from her own experience, she encourages and defends both. Do not be afraid of the disruption of outside…

  2. Observations

    ERIC Educational Resources Information Center

    Joosten, Albert Max

    2016-01-01

    Joosten begins his article by telling us that love and knowledge together are the foundation for our work with children. This combination is at the heart of our observation. With this as the foundation, he goes on to offer practical advice to aid our practice of observation. He offers a "List of Objects of Observation" to help guide our…

  3. Comparing 3D Solar Model Atmospheres with Observations: Hydrogen Lines and Centre-to-limb Variations

    NASA Astrophysics Data System (ADS)

    Pereira, Tiago M. D.; Asplund, Martin; Trampedach, Regner

    Three dimensional hydrodynamical stellar model atmospheres represent a major step forward in stellar spectroscopy. Making use of radiative-hydrodynamical convection simulations that contain no adjustable free parameters, the model atmospheres provide a robust and realistic treatment of convection. These models have been applied to several lines in the Sun and other stars, yielding an excellent agreement with observations (e.g., Asplund et al. (2000) [1]).

  4. June 13, 2013 U.S. East Coast Meteotsunami: Comparing a Numerical Model With Observations

    NASA Astrophysics Data System (ADS)

    Wang, D.; Becker, N. C.; Weinstein, S.; Whitmore, P.; Knight, W.; Kim, Y.; Bouchard, R. H.; Grissom, K.

    2013-12-01

    On June 13, 2013, a tsunami struck the U.S. East Coast and caused several reported injuries. This tsunami occurred after a derecho moved offshore from North America into the Atlantic Ocean. The presence of this storm, the lack of a seismic source, and the fact that tsunami arrival times at tide stations and deep ocean-bottom pressure sensors cannot be attributed to a 'point-source' suggest this tsunami was caused by atmospheric forces, i.e., a meteotsunami. In this study we attempt to reproduce the observed phenomenon using a numerical model with idealized atmospheric pressure forcing resembling the propagation of the observed barometric anomaly. The numerical model was able to capture some observed features of the tsunami at some tide stations, including the time-lag between the time of pressure jump and the time of tsunami arrival. The model also captures the response at a deep ocean-bottom pressure gauge (DART 44402), including the primary wave and the reflected wave. There are two components of the oceanic response to the propagating pressure anomaly, inverted barometer response and dynamic response. We find that the dynamic response over the deep ocean to be much smaller than the inverted barometer response. The time lag between the pressure jump and tsunami arrival at tide stations is due to the dynamic response: waves generated and/or reflected at the shelf-break propagate shoreward and amplify due to the shoaling effect. The evolution of the derecho over the deep ocean (propagation direction and intensity) is not well defined, however, because of the lack of data so the forcing used for this study is somewhat speculative. Better definition of the pressure anomaly through increased observation or high resolution atmospheric models would improve meteotsunami forecast capabilities.

  5. Low-frequency waves at comet 67P/Churyumov-Gerasimenko. Observations compared to numerical simulations

    NASA Astrophysics Data System (ADS)

    Koenders, C.; Perschke, C.; Goetz, C.; Richter, I.; Motschmann, U.; Glassmeier, K. H.

    2016-10-01

    Context. A new type of low-frequency wave was detected by the magnetometer of the Rosetta Plasma Consortium at the comet during the initial months after the arrival of the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. This large-amplitude, nearly continuous wave activity is observed in the frequency range from 30 mHz to 80 mHz where 40 mHz to 50 mHz is the dominant frequency. This type of low frequency is not closely related to the gyrofrequency of newborn cometary ions, which differs from previous wave activity observed in the interaction region of comets with the solar wind. Aims: This work aims to reveal a global view on the wave activity region using simulations of the comet-solar wind interaction region. Parameters, such as wavelength, propagation direction, and propagation patterns, are within the focus of this study. While the Rosetta observations only provide local information, numerical simulations provide further information on the global wave properties. Methods: Standard hybrid simulations were applied to the comet-solar wind interaction scenario. In the model, the ions were described as particles, which allows us to describe kinetic processes of the ions. The electrons were described as a fluid. Results: The simulations exhibit a threefold wave structure of the interaction region. A Mach cone and a Whistler wing are observed downstream of the comet. The third kind of wave activity found are low-frequency waves at 97 mHz, which corresponds to the waves observed by Richter et al. (2015, Ann. Geophys., 33, 1031). These waves are caused by the initial pick-up of the cometary ions that are perpendicular to the solar wind flow and in the interplanetary magnetic field direction. The associated electric current becomes unstable. The simulations show that wave activity is only detectable in the + E hemisphere and that the Mach cone and whistler wings need to be distinguished from the newly found instability driven wave activity. The movie associated to

  6. Safety and efficacy of hysteroscopic sterilization compared with laparoscopic sterilization: an observational cohort study

    PubMed Central

    Mao, Jialin; Pfeifer, Samantha; Schlegel, Peter

    2015-01-01

    Objective To compare the safety and efficacy of hysteroscopic sterilization with the “Essure” device with laparoscopic sterilization in a large, all-inclusive, state cohort. Design Population based cohort study. Settings Outpatient interventional setting in New York State. Participants Women undergoing interval sterilization procedure, including hysteroscopic sterilization with Essure device and laparoscopic surgery, between 2005 and 2013. Main outcomes measures Safety events within 30 days of procedures; unintended pregnancies and reoperations within one year of procedures. Mixed model accounting for hospital clustering was used to compare 30 day and 1 year outcomes, adjusting for patient characteristics and other confounders. Time to reoperation was evaluated using frailty model for time to event analysis. Results We identified 8048 patients undergoing hysteroscopic sterilization and 44 278 undergoing laparoscopic sterilization between 2005 and 2013 in New York State. There was a significant increase in the use of hysteroscopic procedures during this period, while use of laparoscopic sterilization decreased. Patients undergoing hysteroscopic sterilization were older than those undergoing laparoscopic sterilization and were more likely to have a history of pelvic inflammatory disease (10.3% v 7.2%, P<0.01), major abdominal surgery (9.4% v 7.9%, P<0.01), and cesarean section (23.2% v 15.4%, P<0.01). At one year after surgery, hysteroscopic sterilization was not associated with a higher risk of unintended pregnancy (odds ratio 0.84 (95% CI 0.63 to 1.12)) but was associated with a substantially increased risk of reoperation (odds ratio 10.16 (7.47 to 13.81)) compared with laparoscopic sterilization. Conclusions Patients undergoing hysteroscopic sterilization have a similar risk of unintended pregnancy but a more than 10-fold higher risk of undergoing reoperation compared with patients undergoing laparoscopic sterilization. Benefits and risks of both procedures

  7. Comparing simulated PSC optical properties with CALIPSO observations during the 2010 Antarctic winter

    NASA Astrophysics Data System (ADS)

    Zhu, Yunqian; Toon, Owen B.; Pitts, Michael C.; Lambert, Alyn; Bardeen, Charles; Kinnison, Douglas E.

    2017-01-01

    We simulate polar stratospheric clouds (PSCs) during the Antarctic winter of 2010 using the Specified Dynamics version of the Whole Atmosphere Community Climate Model/Community Aerosol and Radiation Model for Atmospheres (SD-WACCM/CARMA) model. The current PSC model contains microphysical schemes for supercooled ternary solutions (STS) and nitric acid trihydrate (NAT) particles, as well as a prognostic treatment for PSC ice particles and dehydration. Our simulations and CALIPSO satellite data suggest two major NAT particle formation mechanisms. The first mechanism is the nucleation of NAT from STS. Our model, with homogeneous nucleation rates of NAT from STS constrained by observations from the Arctic winter of 2010-2011, reproduces optical properties observed by CALIPSO over Antarctica in May and the timing of denitrification observed by the Microwave Limb Sounder within their uncertainties. On the other hand, the CALIPSO data indicate that our simulations are missing clouds containing small NAT particles with large number densities. We suggest these particles are most likely to form from ice clouds or STS in gravity waves, as found by previous investigations. The simulated cloud coverage agrees with the CALIPSO cloud coverage within a few percent on average with a correlation coefficient of 0.83. However, using the CALIPSO classification algorithm, simulated ice clouds often fall into Mix categories under the denitrified and dehydrated conditions. The model needs an improved ice microphysical representation, not only to allow ice particles to be a source of NAT but also to provide information on ice cloud particle number and size so that ice cloud optical properties can be more precisely calculated for comparison with CALIPSO data.

  8. A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies.

    PubMed

    Ibrom, Andreas; Jarvis, Paul G; Clement, Robert; Morgenstern, Kai; Oltchev, Alexander; Medlyn, Belinda E; Wang, Ying Ping; Wingate, Lisa; Moncrieff, John B; Gravenhorst, Gode

    2006-07-01

    Gross canopy photosynthesis (P(g)) can be simulated with canopy models or retrieved from turbulent carbon dioxide (CO2) flux measurements above the forest canopy. We compare the two estimates and illustrate our findings with two case studies. We used the three-dimensional canopy model MAESTRA to simulate P(g) of two spruce forests differing in age and structure. Model parameter acquisition and model sensitivity to selected model parameters are described, and modeled results are compared with independent flux estimates. Despite higher photon fluxes at the site, an older German Norway spruce (Picea abies L. (Karst.)) canopy took up 25% less CO2 from the atmosphere than a young Scottish Sitka spruce (Picea sitchensis (Bong.) Carr.) plantation. The average magnitudes of P(g) and the differences between the two canopies were satisfactorily represented by the model. The main reasons for the different uptake rates were a slightly smaller quantum yield and lower absorptance of the Norway spruce stand because of a more clumped canopy structure. The model did not represent the scatter in the turbulent CO2 flux densities, which was of the same order of magnitude as the non-photosynthetically-active-radiation-induced biophysical variability in the simulated P(g). Analysis of residuals identified only small systematic differences between the modeled flux estimates and turbulent flux measurements at high vapor pressure saturation deficits. The merits and limitations of comparative analysis for quality evaluation of both methods are discussed. From this analysis, we recommend use of both parameter sets and model structure as a basis for future applications and model development.

  9. COMPARATIVE STUDY OF ASYMMETRY ORIGIN OF GALAXIES IN DIFFERENT ENVIRONMENTS. I. OPTICAL OBSERVATIONS

    SciTech Connect

    Plauchu-Frayn, I.; Coziol, R. E-mail: rcoziol@astro.ugto.m

    2010-06-15

    This paper presents the first of two analyses about the influence of environment on the formation and evolution of galaxies observed in the nearby universe. For our study, we used three different samples representing different density environments: galaxies in Compact Groups (HCGs), Isolated Pairs of Galaxies (KPGs), and Isolated Galaxies (KIGs), which were taken as references. Usingboth characteristic isophotal parameters and evidence of asymmetries in the optical and the near-infrared, we are able to establish differences in the characteristics of galaxies with different morphologies in different environments, allowing us to better understand their different formation histories. In this first paper, we present the isophotal and asymmetry analyses of a sample of 214 galaxies in different environments observed in the optical (V and I images). For each galaxy, we have determined different characteristic isophotal parameters and V - I color profiles, as a function of semi-major axis, and performed a full asymmetry analysis in residual images using the V filter. Evidence of asymmetry in the optical is almost missing in the KIG sample and significantly more common in the KPG than in the HCG samples. Our isophotal analysis suggests that the stellar populations in the HCG galaxies are older and more dynamically relaxed than in the KPG. The HCG galaxies seem to be at a more advanced stage of interaction than the KPGs. One possible explanation is that these structures formed at different epochs: compact groups of galaxies would have formed before close pairs of galaxies, which only began interacting recently. However, similarities in the formation process of galaxies with same morphology suggest CGs and close pairs of galaxies share similar conditions; they are new structures forming relatively late in low-density environments.

  10. GEM-CEDAR Challenge: Comparing Ionospheric Models with Poynting Flux from DMSP Observations

    NASA Technical Reports Server (NTRS)

    Rastaetter, Lutz; Kuznetsova, Maria; Shim, Ja-Soon; Hesse, Michael; Knipp, Delores J.; Weimer, Daniel R.; Fuller-Rowell, Timothy J.; Ridley, Aaron J.; Raeder, Joachim; Maruyama, Naomi; Kilcomons, Liam; Wittberger, Michael James

    2011-01-01

    As part to the GEM-CEDAR challenge we are extending the model-data comparisons to electrodynamic in-situ measurements in low-Earth orbit. We use DMSP observations of electric and magnetic fields to compute Poynting Flux values along the satellite track in high latitudes including the auroral zones and the polar cap. Models of the ionosphere that include electrodynamic parameters have been run for five events selected for the GEM-CEDAR modeling challenge for which DMSP data are available for comparison. Combined with a magnetic field model we use the modeled electric fields to compute Poynting Flux and Joule Dissipation values from outputs of CTIPe, TIE-GCM, the ionospheric electrodynamics solvers of the SWMF, LFM and OpenGGCM magnetosphere-ionosphere coupled models, and the Weimer electric field model. The online metrics analysis tool at the Community Coordinated Modeling Center (CCMC) has been updated to handle the analysis of separate short segments of available data (high-latitude sections of the satellite orbit) with model outputs to analyze how well auroral patterns are being reproduced by the models. We present initial results from the new analysis tool in terms of model yields (ratio of the difference between maximum and minimum values of model results to the observation), timing/location errors of local maxima in the inbound and outbound auroral crossings as well as cross-correlations for individual passes. We collect the information for many DMSP passes and present an analysis for model performance during quiet and geomagnetically disturbed time periods using half-orbit integrated values as well.

  11. Observation

    ERIC Educational Resources Information Center

    Kripalani, Lakshmi A.

    2016-01-01

    The adult who is inexperienced in the art of observation may, even with the best intentions, react to a child's behavior in a way that hinders instead of helping the child's development. Kripalani outlines the need for training and practice in observation in order to "understand the needs of the children and...to understand how to remove…

  12. Are periprosthetic tissue reactions observed after revision of total disc replacement comparable to the reactions observed after total hip or knee revision surgery?

    PubMed Central

    Punt, Ilona M.; Austen, Shennah; Cleutjens, Jack P.M.; Kurtz, Steven M.; ten Broeke, René H.M.; van Rhijn, Lodewijk W.; Willems, Paul C.; van Ooij, André

    2011-01-01

    Study design Comparative study. Objective To compare periprosthetic tissue reactions observed after total disc replacement (TDR), total hip arthroplasty (THA) and total knee arthroplasty (TKA) revision surgery. Summary of background data Prosthetic wear debris leading to particle disease, followed by osteolysis, is often observed after THA and TKA. Although the presence of polyethylene (PE) particles and periprosthetic inflammation after TDR has been proven recently, osteolysis is rarely observed. The clinical relevance of PE wear debris in the spine remains poorly understood. Methods Number, size and shape of PE particles, as well as quantity and type of inflammatory cells in periprosthetic tissue retrieved during Charité TDR (n=22), THA (n=10) and TKA (n=4) revision surgery were compared. Tissue samples were stained with hematoxylin/eosin and examined by using light microscopy with bright field and polarized light. Results After THA, large numbers of PE particles <6 µm were observed, which were mainly phagocytosed by macrophages. The TKA group had a broad size range with many larger PE particles and more giant cells. In TDR, the size range was similar to that observed in TKA. However, the smallest particles were the most prevalent with 75% of the particles being <6 µm, as seen in revision THA. In TDR, both macrophages and giant cells were present with a higher number of macrophages. Conclusions Both small and large PE particles are present after TDR revision surgery compatible with both THA and TKA wear patterns. The similarities between periprosthetic tissue reactions in the different groups may give more insight in the clinical relevance of PE particles and inflammatory cells in the lumbar spine. The current findings may help to improve TDR design as applied from technologies previously developed in THA and TKA with the goal of a longer survival of TDR. PMID:21336235

  13. Mean Atlantic Meridional Overturning Circulation Across 26.5 degs N from Eddy-Resolving Simulations Compared to Observations

    DTIC Science & Technology

    2012-03-30

    Mean Atlantic meridional overturning circulation across 26.5N from eddy-resolving simulations compared to observations X. Xu,1 W. J. Schmitz Jr.,2 H...Observations along 26.5N are used to examine the time mean structure of the Atlantic meridional overturning circulation (AMOC) in eddy-resolving simulations...other ocean general circulation models and includes a secondary transport maximum near 4000 m corresponding to Nordic Seas Overflow Water. The modeled

  14. Posthole Broadband Sensor Emplacement vs. Surface Vaults: Observations of Comparative Noise Performance and Trade-offs

    NASA Astrophysics Data System (ADS)

    Sweet, J. R.; Beaudoin, B. C.; Barstow, N.; Pfeifer, M.; Anderson, K. R.; Frassetto, A.

    2015-12-01

    Advances in seismometer design have diversified the range of instruments available for use in temporary field installations. IRIS programs, primarily PASSCAL and the Transportable Array (TA), have helped steer development of these new instruments to meet these evolving needs. PASSCAL operates a small pool of posthole broadband sensors, purpose built for direct burial. Near surface posthole installations are a new, cost effective, and logistically simple technique for broadband emplacement that is an alternative to the vault installations used in portable broadband seismic experiments for nearly 30 years. Direct burial installation is limited to the time and effort required to dig the borehole and emplace the sensor, thus reducing both material costs and time to install. Also, in Alaska, extreme environments and difficult logistics make standard TA tank vaults inappropriate for most sites. TA has developed improved deployment strategies for these environments. There, holes for posthole sensors are hammer- drilled or augered to several meters depth in soil, permafrost, or bedrock and then cased. These emplacement costs are generally less than standard TA vaults. We compare various installation techniques for test cases as well as general deployments of PASSCAL and TA stations. Automated noise performance analyses have been part of the TA throughout its operation, but until recently vault performance for portable installations supported by the PASSCAL program was sparse. In this study, we select a suite of co-located direct burial and surface vault installations and compare their noise performance using probability density functions. Our initial analyses suggest that direct burial sensors have lower noise levels than vault installations on both horizontal and vertical channels across a range of periods spanning <1 s to 100 s. However, most of these initial experiments for PASSCAL were with sensors not purpose built for direct burial and it became obvious that a sensor

  15. Comparing ECMWF AOD with AERONET observations at visible and UV wavelengths

    NASA Astrophysics Data System (ADS)

    Cesnulyte, V.; Lindfors, A. V.; Pitkänen, M. R. A.; Lehtinen, K. E. J.; Morcrette, J.-J.; Arola, A.

    2014-01-01

    This paper presents validation results of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System MACC (Monitoring Atmospheric Composition and Climate) re-analysis aerosol optical depth (AOD) for the period 2003-2006. We evaluate the MACC AOD at a UV wavelength (340 nm) and at mid-visible (500 and 550 nm) by comparing against ground-based AERONET measurements at 12 sites. The AERONET sites cover various parts of the globe and are categorized in three groups: urban/anthropogenic, biomass burning and dust, depending on the typically dominating aerosol type. This is the first time a global model such as the ECMWF has been evaluated for the performance of AOD at a UV wavelength. The results show that the MACC system generally provides a good representation of the AOD on a monthly basis, showing a realistic seasonal cycle. The model is mostly able to capture major dust load events and also the peak months of biomass burning correctly. For Kanpur and Solar Village, however, the model overestimates the AOD during the monsoon period when the aerosol load is generally low. When comparing hourly AOD values, the model-measurement agreement is better for biomass burning and dust sites than for urban sites, with an average correlation coefficient around 0.90 for biomass burning sites, around 0.77 for dust sites, and below 0.70 for urban sites. The AOD at 500 nm averaged over all sites shows only a small systematic difference between modeled and measured values, with a relative mean bias of 0.02. However, for the AOD at 340 nm the relative mean bias is -0.2. All sites included in the study show a relative mean bias at 340 nm smaller (or more negative) than that at 500 nm, indicating a strong wavelength dependence in the performance of the AOD in the MACC system. A comparison against fine and coarse mode AOD of the AERONET indicates that this has to do with the size distribution of the model: generally, the ECMWF model overestimates the

  16. Comparing ECMWF AOD with AERONET observations at visible and UV wavelengths

    NASA Astrophysics Data System (ADS)

    Cesnulyte, V.; Lindfors, A. V.; Pitkänen, M. R. A.; Lehtinen, K. E. J.; Morcrette, J. J.; Arola, A.

    2013-07-01

    This paper presents validation results of the ECMWF Integrated Forecasting System MACC re-analysis aerosol optical depth (AOD) for the period 2003-2006. We evaluate the MACC AOD at a UV wavelength (340 nm) and at mid-visible (500 and 550 nm) by comparing against ground-based AERONET measurements at 12 sites. The AERONET sites cover various parts of the globe and are categorized in three groups: urban/anthropogenic, biomass burning and dust, depending on the typically dominating aerosol type. This is the first time when a global model such as the ECMWF is evaluated for the performance of AOD at a UV wavelength. The results show that the MACC system generally provides a good representation of the AOD on a monthly basis, showing a realistic seasonal cycle. The model is mostly able to capture major dust load events and also the peak months of biomass burning correctly. For Kanpur and Solar Village, however, the model overestimates the AOD during the monsoon period when the aerosol load is generally low. When comparing hourly AOD values, the model-measurement agreement is better for biomass burning and dust sites than for urban sites, with an average correlation coefficient around 0.90 for biomass burning sites, around 0.77 for dust sites, and below 0.70 for urban sites. The AOD at 500 nm averaged over all sites shows only a small systematic difference between modeled and measured values, with a relative mean bias of 0.02. However, for the AOD at 340 nm the relative mean bias is -0.2. All sites included in the study show a relative mean bias at 340 nm smaller (or more negative) than that at 500 nm, indicating a strong wavelength-dependence in the performance of the AOD in the MACC system. A comparison against fine and coarse mode AOD of the AERONET indicates that this has to do with the size distribution of the model: generally, the ECMWF model overestimates the contribution by coarse mode particles.

  17. A comparative study of local galaxy clusters - I. Derived X-ray observables

    NASA Astrophysics Data System (ADS)

    Rozo, E.; Rykoff, E. S.; Bartlett, J. G.; Evrard, A.

    2014-02-01

    We examine systematic differences in the derived X-ray properties of galaxy clusters as reported by three different groups: Vikhlinin et al., Mantz et al. and Plank Collaboration. The sample overlap between any two pairs of works ranges between 16 to 28 galaxy clusters. We find systematic differences in most reported X-ray properties, including the total cluster mass, M500. The most extreme case is an average 45 ± 5 per cent difference in cluster mass between the Plank Collaboration and Mantz et al., for clusters at z > 0.13 (averaged over 16 clusters). These differences also induce differences in cluster observables defined within an R500 aperture. After accounting for aperture differences, we find very good agreement in gas mass estimates between the different groups. However, the soft-band X-ray luminosity, LX, core-excised spectroscopic temperature, TX, and gas thermal energy, YX = MgasTX display mean differences at the 5-15 per cent level. We also find that the low (z ≤ 0.13) and high (z ≥ 0.13) redshift galaxy cluster samples in Plank Collaboration appear to be systematically different: the YSZ/YX ratio for each of these two sub-samples is ln (YSZ/YX) = -0.06 ± 0.04 and ln (YSZ/YX) = 0.08 ± 0.04, respectively.

  18. Comparing foreshock characteristics and foreshock forecasting in observed and simulated earthquake catalogs

    NASA Astrophysics Data System (ADS)

    Ogata, Yosihiko; Katsura, Koichi

    2014-11-01

    In this paper, we compare the empirical results regarding foreshocks obtained from the Japan data with results for synthetic catalogs in order to clarify whether or not the corresponding results are consistent with the description of the seismicity by a superposition of background activity and epidemic-type aftershock sequence (ETAS) models. This question is important, because it is still controversially discussed whether the nucleation process of large earthquakes is driven by seismically cascading (ETAS type) or by aseismic accelerating processes. To explore the foreshock characteristics, we first applied the same clustering algorithms to real and synthetic catalogs and analyzed the temporal, spatial, and magnitude distributions of the selected foreshocks. Most properties are qualitatively the same in the real data and in synthetic catalogs. However, we find some quantitative differences particularly in the temporal acceleration, spatial convergence, and magnitude dependence, which also depend on the assumed synthetic catalogs. Furthermore, we calculated forecast scores based on a single-link cluster algorithm which could be appropriate for real-time applications. We find that the Japan Meteorological Agency catalog yields higher scores than all synthetic catalogs and that the ETAS models having the same magnitude sequence as the original catalog performs better (more close to the reality) than ETAS models with randomly picked magnitudes. We also find that the ETAS model that takes account of the triggering effect by small earthquakes below threshold magnitude performs more closely to the reality.

  19. Passive SWIR airglow illuminated imaging compared with NIR-visible for low-light nighttime observations

    NASA Astrophysics Data System (ADS)

    Dayton, David C.; Allen, Jeffery; Gonglewski, John D.; Nolasco, Rudolph; Myers, Michael; Burns, Dennis; Mons, Ishan; Maia, Francisco

    2011-05-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band with wavelength between 0.9 and 1.7 μm. By examining images in an urban and a rural setting, we investigate the correlation between the appearances of passive dark of night images in the SWIR with NIR- visible. The experimental setup consists of two sensors, a NIR-visible CCD and an InGaAs array sensitive in the SWIR, both colocated on an AZ-EL mount, and both co-boresighted so that different viewing angles of the sky and terrestrial scenes are possible. By making corrections for focal length and pixel size, the visible and SWIR data can be compared. After taking several nights of data in the urban environment of Albuquerque, NM, the entire system was then re-located to a rural location on the island of Kauai in a rural setting with very low ambient light. It is shown that under most conditions the SWIR sensor produces significantly better imagery using the airglow illumination source.

  20. Comparative observations on levels of mercury in scalp hair of humans from different Islands

    NASA Astrophysics Data System (ADS)

    Renzoni, Aristeo

    1992-09-01

    Following the Minamata events, an extraordinary number of studies concerning mercury toxicity and human health have been undertaken. Particular attention has been given to the evaluation of the dose-response relationship, i.e., the body burden at which (evaluated through the mercury analyses in blood or hair) the risk of poisoning begins. The results of a comparative study concerning levels of mercury in the hair of fishermen living in small islands who eat seafood more than four times per week show that in two areas only, and only in a few cases in these areas, the mercury in the hair exceeds the limit at which a possible risk could exist. In fact, the limit of 50 mg/g of total mercury in the hair (indicated as the lower limit above which a possible risk could occur) is surpassed by nine fishermen out of a total of 39 at station 1 and by four fishermen out of a total of 26 at station 3. The average value at station 1 is 36.38 mg/g and that at station 3 is 30.31 mg. Many countries have set legal limits of mercury for seafood, but evidently the system does not offer a true protection for man. Only the provisional tolerable weekly intake (PTWI), as repeatedly suggested by WHO, should be considered the best guideline to prevent possibly harmful consequences.

  1. Comparing Goldstone Solar System Radar Earth-based Observations of Mars with Orbital Datasets

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Larsen, K. W.; Jurgens, R. F.; Slade, M. A.

    2005-01-01

    The Goldstone Solar System Radar (GSSR) has collected a self-consistent set of delay-Doppler near-nadir radar echo data from Mars since 1988. Prior to the Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) global topography for Mars, these radar data provided local elevation information, along with radar scattering information with global coverage. Two kinds of GSSR Mars delay-Doppler data exist: low 5 km x 150 km resolution and, more recently, high (5 to 10 km) spatial resolution. Radar data, and non-imaging delay-Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. Interpretation of these parameters, while limited by the complexities of electromagnetic scattering, provide information directly relevant to geophysical and geomorphic analyses of Mars. In this presentation we want to demonstrate how to compare GSSR delay-Doppler data to other Mars datasets, including some idiosyncracies of the radar data. Additional information is included in the original extended abstract.

  2. Comparing Foreshock Characteristics and Foreshock Forecasting in Observed and Simulated Earthquake Catalogs

    NASA Astrophysics Data System (ADS)

    Ogata, Y.

    2014-12-01

    In our previous papers (Ogata et al., 1995, 1996, 2012; GJI), we characterized foreshock activity in Japan, and then presented a model that forecasts the probability that one or more earthquakes form a foreshock sequence; then we tested prospectively foreshock probabilities in the JMA catalog. In this talk, I compare the empirical results with results for synthetic catalogs in order to clarify whether or not these results are consistent with the description of the seismicity by a superposition of background activity and epidemic-type aftershock sequences (ETAS models). This question is important, because it is still controversially discussed whether the nucleation process of large earthquakes is driven by seismically cascading (ETAS-type) or by aseismic accelerating processes. To explore the foreshock characteristics, I firstly applied the same clustering algorithms to real and synthetic catalogs and analyzed the temporal, spatial and magnitude distributions of the selected foreshocks, to find significant differences particularly in the temporal acceleration and magnitude dependence. Finally, I calculated forecast scores based on a single-link cluster algorithm which could be appropriate for real-time applications. I find that the JMA catalog yields higher scores than all synthetic catalogs and that the ETAS models having the same magnitude sequence as the original catalog performs significantly better (more close to the reality) than ETAS-models with randomly picked magnitudes.

  3. Technology assessment: observer study directly compares screen/film to CR mammography

    NASA Astrophysics Data System (ADS)

    Fletcher-Heath, Lynn; Richards, Anne; Ryan-Kron, Susan

    2007-03-01

    A new study supports and expands upon a previous reporting that computed radiography (CR) mammography offers as good, or better, image quality than state-of-the-art screen/film mammography. The suitability of CR mammography is explored through qualitative and quantitative study components: feature comparison and cancer detection rates of each modality. Images were collected from 150 normal and 50 biopsy-confirmed subjects representing a range of breast and pathology types. Comparison views were collected without releasing compression, using automatic exposure control on Kodak MIN-R films, followed by CR. Digital images were displayed as both softcopy (S/C) and hardcopy (H/C) for the feature comparison, and S/C for the cancer detection task. The qualitative assessment used preference scores from five board-certified radiologists obtained while viewing 100 screen/film-CR pairs from the cancer subjects for S/C and H/C CR output. Fifteen general image-quality features were rated, and up to 12 additional features were rated for each pair, based on the pathology present. Results demonstrate that CR is equivalent or preferred to conventional mammography for overall image quality (89% S/C, 95% H/C), image contrast (95% S/C, 98% H/C), sharpness (86% S/C, 93% H/C), and noise (94% S/C, 91% H/C). The quantitative objective was satisfied by asking 10 board-certified radiologists to provide a BI-RADS TM score and probability of malignancy per breast for each modality of the 200 cases. At least 28 days passed between observations of the same case. Average sensitivity and specificity was 0.89 and 0.82 for CR and 0.91 and 0.82 for screen/film, respectively.

  4. Multicenter, Phase 3 Trial Comparing Selenium Supplementation With Observation in Gynecologic Radiation Oncology

    SciTech Connect

    Muecke, Ralph; Schomburg, Lutz; Glatzel, Michael; Berndt-Skorka, Regina; Baaske, Dieter; Reichl, Berthold; Buentzel, Jens; Kundt, Guenter; Prott, Franz J.; Vries, Alexander de; Stoll, Guenther; Kisters, Klaus; Bruns, Frank; Schaefer, Ulrich; Willich, Norman; Micke, Oliver

    2010-11-01

    Purpose: We assessed whether adjuvant supplementation with selenium improves the selenium status and reduces side effects of patients treated by radiotherapy (RT) for cervical and uterine cancer. Methods and Materials: Whole-blood selenium concentrations were measured in patients with cervical cancer (n = 11) and uterine cancer (n = 70) after surgical treatment, during RT, at the end of RT, and 6 weeks after RT. Patients with initial selenium concentrations of less than 84{mu}g/L were randomized before RT either to receive 500 {mu}g of selenium (in the form of sodium selenite [selenase (registered) , biosyn Arzneimittel GmbH, Fellbach, Germany]) by mouth on the days of RT and 300 {mu}g of selenium on the days without RT or to receive no supplement during RT. The primary endpoint of this multicenter Phase 3 study was to assess the efficiency of selenium supplementation during RT; the secondary endpoint was to decrease radiation-induced diarrhea and other RT-dependent side effects. Results: A total of 81 patients were randomized. We enrolled 39 in the selenium group (SG) and 42 in the control group (CG). Selenium levels did not differ between the SG and CG upon study initiation but were significantly higher in the SG at the end of RT. The actuarial incidence of diarrhea of Grade 2 or higher according to Common Toxicity Criteria (version 2) in the SG was 20.5% compared with 44.5% in the CG (p = 0.04). Other blood parameters, Eastern Cooperative Oncology Group performance status, and self-reported quality of life were not different between the groups. Conclusions: Selenium supplementation during RT is effective in improving blood selenium status in selenium-deficient cervical and uterine cancer patients and reduces the number of episodes and severity of RT-induced diarrhea.

  5. Reduction in accuracy of genomic prediction for ordered categorical data compared to continuous observations

    PubMed Central

    2014-01-01

    Background Accuracy of genomic prediction depends on number of records in the training population, heritability, effective population size, genetic architecture, and relatedness of training and validation populations. Many traits have ordered categories including reproductive performance and susceptibility or resistance to disease. Categorical scores are often recorded because they are easier to obtain than continuous observations. Bayesian linear regression has been extended to the threshold model for genomic prediction. The objective of this study was to quantify reductions in accuracy for ordinal categorical traits relative to continuous traits. Methods Efficiency of genomic prediction was evaluated for heritabilities of 0.10, 0.25 or 0.50. Phenotypes were simulated for 2250 purebred animals using 50 QTL selected from actual 50k SNP (single nucleotide polymorphism) genotypes giving a proportion of causal to total loci of.0001. A Bayes C π threshold model simultaneously fitted all 50k markers except those that represented QTL. Estimated SNP effects were utilized to predict genomic breeding values in purebred (n = 239) or multibreed (n = 924) validation populations. Correlations between true and predicted genomic merit in validation populations were used to assess predictive ability. Results Accuracies of genomic estimated breeding values ranged from 0.12 to 0.66 for purebred and from 0.04 to 0.53 for multibreed validation populations based on Bayes C π linear model analysis of the simulated underlying variable. Accuracies for ordinal categorical scores analyzed by the Bayes C π threshold model were 20% to 50% lower and ranged from 0.04 to 0.55 for purebred and from 0.01 to 0.44 for multibreed validation populations. Analysis of ordinal categorical scores using a linear model resulted in further reductions in accuracy. Conclusions Threshold traits result in markedly lower accuracy than a linear model on the underlying variable. To achieve an accuracy equal or

  6. Comparing ligo merger rate observations with theory: distribution of star-forming conditions

    SciTech Connect

    Belczynski, Kryzysztof; Kopparapu, R; O' Shaughnessy, R

    2008-01-01

    -forming conditions depends on the binary evolution model and on the amount of relevant variation in star-forming conditions. For example, if after further comparison with electromagnetic and gravitational wave observations future population synthesis models suggest all BH-BH binary mergers occur promptly and therefore are associated with well-studied present-day star formation, the associated composition-related systematic uncertainty could be lower than the pessimistic value quoted above. Further, as gravitational wave detectors will make available many properties of each merger -- binary component masses, spins, and even short GRB associations and host galaxies could be available -- many detections can still be exploited to create high-precision constraints on binary compact object formation models.

  7. Comparing Stable Water Isotope Variation in Atmospheric Moisture Observed over Coastal Water and Forests

    NASA Astrophysics Data System (ADS)

    Lai, C. T.; Rambo, J. P.; Welp, L. R.; Bible, K.; Hollinger, D. Y.

    2014-12-01

    Stable oxygen (δ18O) and hydrogen (δD) isotopologues of atmospheric moisture are strongly influenced by large-scale synoptic weather cycles, surface evapotranspiration and boundary layer mixing. Atmospheric water isotope variation has been shown to empirically relate to relative humidity (Rh) of near surface moisture, and to a less degree, air temperature. Continuous δ18O and δD measurements are becoming more available, providing new opportunities to investigate processes that control isotope variability. This study shows the comparison of δ18O and δD measured at a continental location and over coastal waters for 3 seasons (spring to fall, 2014). The surface moisture isotope measurements were made using two LGR spectroscopy water vapor isotope analyzers (Los Gatos Research Inc.), one operated in an old-growth coniferous forest at Wind River field station, WA (45.8205°N, 121.9519°W), and another sampling marine air over seawater at the Scripps Pier in San Diego, CA (32.8654°N, 117.2536°W), USA. Isotope variations were measured at 1Hz and data were reported as hourly averages with an overall accuracy of ±0.1‰ for δ18O, ±0.5‰ for δ2H. Day-to-day variations in δ18O and δD are shown strongly influenced by synoptic weather events at both locations. Boundary layer mixing between surface moisture and the dry air entrained from the free troposphere exerts a midday maximum and a consistent diel pattern in deuterium excess (dx). At the forest site, surface moisture also interacts with leaf water through transpiration during the day and re-equilibration at night. The latter occurs by retro-diffusion of atmospheric H2O molecules into leaf intercellular space, which becomes intensified as Rh increaes after nightfall, and continues until sunrise, to counter-balance the evaporative isotopic enrichment in leaf water on a daily basis. These vegetation effects lead to negative dx values consistently observed at nighttime in this continental location that were not

  8. Interannual sedimentary effluxes of alkalinity in the southern North Sea: Model results compared with summer observations.

    NASA Astrophysics Data System (ADS)

    Paetsch, Johannes; Kuehn, Wilfried; Six, Katharina

    2016-04-01

    Alkalinity generation in the sediment of the southern North Sea is the focus of several recent studies. One motivation for these efforts is the potentially enhanced buffering capacity of anthropogenic CO2 invasion into the corresponding pelagic system. An adaptation of a global multilayer sediment model (Heinze et al., 1999) in combination with a pelagic ecosystem model for shelf sea dynamics was used to study the benthic reactions on very different annual cycles (2001 - 2009) including the River Elbe summer flooding in 2002. The focus of this study is the efflux of alkalinity, their different contributors (aerobic respiration, denitrification, net sulfate reduction, calcite dissolution, nitrification) and their seasonal and interannual cycles. Similar to the observations covering the southern North Sea (Brenner et al., 2015) the model results show large horizontal gradients from the near-shore high productive areas with benthic remineralization up to Rmin = 10.6 mol C m-2 yr-1 and TA generation RTA = 2 mol C m-2 yr-1 to off-shore moderate productive areas with mean Rmin = 2.5 mol C m-2 yr-1 and mean TA generation RTA = 0.4 mol C m-2 yr-1. Beside calcite dissolution, aerobic respiration (producing ammonium) and denitrification are the largest contributors to alkalinity generation. Nitrification is reducing alkalinity in the sediment. Due to low regenerated primary production in summer, the year 2001 exhibits the lowest input of particulate organic matter into the sediment (POCexp=2.3 mol C m-2 yr-1), while the year 2003 exhibits the highest export production (POCexp=2.6 mol C m-2 yr-1). The biogeochemical reactions and the effluxes from the sediment follow these pelagic amplitudes with a time lag of about one year with damped amplitudes. References Brenner, H., Braeckman, U., Le Guitton, M., Meysman, F.J.R., 2015. The impact of sedimentary alkalinity release on the water column CO2 system in the North Sea. Biogeosiences Discussion, 12(15): 12395-12453. Heinze, C

  9. Patient satisfaction with primary care: an observational study comparing anthroposophic and conventional care

    PubMed Central

    Esch, Barbara M; Marian, Florica; Busato, André; Heusser, Peter

    2008-01-01

    Background This study is part of a cross-sectional evaluation of complementary medicine providers in primary care in Switzerland. It compares patient satisfaction with anthroposophic medicine (AM) and conventional medicine (CON). Methods We collected baseline data on structural characteristics of the physicians and their practices and health status and demographics of the patients. Four weeks later patients assessed their satisfaction with the received treatment (five items, four point rating scale) and evaluated the praxis care (validated 23-item questionnaire, five point rating scale). 1946 adult patients of 71 CON and 32 AM primary care physicians participated. Results 1. Baseline characteristics: AM patients were more likely female (75.6% vs. 59.0%, p < 0.001) and had higher education (38.6% vs. 24.7%, p < 0.001). They suffered more often from chronic illnesses (52.8% vs. 46.2%, p = 0.015) and cancer (7.4% vs. 1.1%). AM consultations lasted on average 23,3 minutes (CON: 16,8 minutes, p < 0.001). 2. Satisfaction: More AM patients expressed a general treatment satisfaction (56.1% vs. 43.4%, p < 0.001) and saw their expectations completely fulfilled at follow-up (38.7% vs. 32.6%, p < 0.001). AM patients reported significantly fewer adverse side effects (9.3% vs. 15.4%, p = 0.003), and more other positive effects from treatment (31.7% vs. 17.1%, p < 0.001). Europep: AM patients appreciated that their physicians listened to them (80.0% vs. 67.1%, p < 0.001), spent more time (76.5% vs. 61.7%, p < 0.001), had more interest in their personal situation (74.6% vs. 60.3%, p < 0.001), involved them more in decisions about their medical care (67.8% vs. 58.4%, p = 0.022), and made it easy to tell the physician about their problems (71.6% vs. 62.9%, p = 0.023). AM patients gave significantly better rating as to information and support (in 3 of 4 items p [less than or equal to] 0.044) and for thoroughness (70.4% vs. 56.5%, p < 0.001). Conclusion AM patients were significantly

  10. How Physicians, Patients, and Observers Compare on the Use of Qualitative and Quantitative Measures of Physician-Patient Communication.

    PubMed

    Gordon, Howard S; Street, Richard L

    2016-12-01

    The purpose of this study was to compare several different measures of physician-patient communication. We compared data derived from different measures of three communication behaviors, patient participation, physician information giving, and physician participatory decision-making (PDM) style, from 83 outpatient visits to oncology or thoracic surgery clinics for pulmonary nodules or lung cancer. Communication was measured with rating scales completed by patients and physicians after the consultation and by two different groups of external observers who used rating scales or coded the frequency of communication behaviors, respectively, after listening to an audio recording of the consultation. Measures were compared using Pearson's correlations. Correlations of patients' and physicians' ratings of patient participation (r = .04) and physician PDM style (r = .03) were low and not significant (p > .0083, Bonferroni-adjusted). Correlations of observers' ratings with patients' or physicians' ratings for patient participation and physician PDM style were moderate or low (r = .15, .27, .07, and .01, respectively) but were not statistically significant (p > .0083, Bonferroni-adjusted). Correlations between observers' ratings and frequency measures were .31, .52, and .63 and were statistically significant with p values .005, <.0001, and <.0001, respectively, for PDM style, information giving, and patient participation. Our findings highlight the potential for using observers' ratings as an alternate measure of communication to more labor intensive frequency measures.

  11. Radiological surveillance of formerly asbestos-exposed power industry workers: rates and risk factors of benign changes on chest X-ray and MDCT

    PubMed Central

    2014-01-01

    Background To determine the prevalence of asbestos-related changes on chest X-ray (CXR) and low-dose multidetector-row CT (MDCT) of the thorax in a cohort of formerly asbestos-exposed power industry workers and to assess the importance of common risk factors associated with specific radiological changes. Methods To assess the influence of selected risk factors (age, time since first exposure, exposure duration, cumulative exposure and pack years) on typical asbestos-related radiographic changes, we employed multiple logistic regression and receiver operating characteristic (ROC) analysis. Results On CXR, pleural changes and asbestosis were strongly associated with age, years since first exposure and exposure duration. The MDCT results showed an association between asbestosis and age and between plaques and exposure duration, years since first exposure and cumulative exposure. Parenchymal changes on CXR and MDCT, and diffuse pleural thickening on CXR were both associated with smoking. Using a cut-off of 55 years for age, 17 years for exposure duration and 28 years for latency, benign radiological changes in the cohort with CXR could be predicted with a sensitivity of 82.0% for all of the three variables and a specificity of 47.4%, 39.0% and 40.6%, respectively. Conclusions Participants aged 55 years and older and those with an asbestos exposure of at least 17 years or 28 years since first exposure should be seen as having an increased risk of abnormal radiological findings. For implementing a more focused approach the routine use of low-dose MDCT rather than CXR at least for initial examinations would be justified. PMID:24808921

  12. Efficiency of the human observer compared to an ideal observer based on a generalized NEQ which incorporates scatter and geometric unsharpness: evaluation with a 2AFC experiment

    NASA Astrophysics Data System (ADS)

    Kyprianou, Iacovos S.; Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R.; Gallas, Brandon D.; Myers, Kyle J.

    2005-04-01

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQD) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and geometric unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTFD, and the detector Normalized-Noise-Power-Spectrum (NNPSD). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQD was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100-300 um) filled with iodine contrast (concentrations between 0-120 mg/cm3) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 um pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and geometric unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system.

  13. Efficiency of the Human Observer Compared to an Ideal Observer Based on a Generalized NEQ Which Incorporates Scatter and Geometric Unsharpness: Evaluation with a 2AFC Experiment.

    PubMed

    Kyprianou, Iacovos S; Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R; Gallas, Brandon D; Myers, Kyle J

    2005-01-01

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQ(D)) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and geometric unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTF(D), and the detector Normalized-Noise-Power-Spectrum (NNPS(D)). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQ(D) was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100-300 μm) filled with iodine contrast (concentrations between 0-120 mg/cm(3)) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 μm pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and geometric unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system.

  14. Efficiency of the Human Observer Compared to an Ideal Observer Based on a Generalized NEQ Which Incorporates Scatter and Geometric Unsharpness: Evaluation with a 2AFC Experiment

    PubMed Central

    Kyprianou, Iacovos S.; Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R.; Gallas, Brandon D.; Myers, Kyle J.

    2011-01-01

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQD) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and geometric unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTFD, and the detector Normalized-Noise-Power-Spectrum (NNPSD). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQD was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100–300 μm) filled with iodine contrast (concentrations between 0–120 mg/cm3) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 μm pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and geometric unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system. PMID:21311735

  15. Learning by viewing versus learning by doing: A comparative study of observer and participant experiences during an interprofessional simulation training.

    PubMed

    Reime, Marit Hegg; Johnsgaard, Tone; Kvam, Fred Ivan; Aarflot, Morten; Engeberg, Janecke Merethe; Breivik, Marit; Brattebø, Guttorm

    2017-01-01

    Larger student groups and pressure on limited faculty time have raised the question of the learning value of merely observing simulation training in emergency medicine, instead of active team participation. The purpose of this study was to examine observers and hands-on participants' self-reported learning outcomes during simulation-based interprofessional team training regarding non-technical skills. In addition, we compared the learning outcomes for different professions and investigated team performance relative to the number of simulations in which they participated. A concurrent mixed-method design was chosen to evaluate the study, using questionnaires, observations, and focus group interviews. Participants included a total of 262 postgraduate and bachelor nursing students and medical students, organised into 44 interprofessional teams. The quantitative data showed that observers and participants had similar results in three of six predefined learning outcomes. The qualitative data emphasised the importance of participating in different roles, training several times, and training interprofessionally to enhance realism. Observing simulation training can be a valuable learning experience, but the students' preferred hands-on participation and learning by doing. For this reason, one can legitimise the observer role, given the large student groups and limited faculty time, as long as the students are also given some opportunity for hands-on participation in order to become more confident in their professional roles.

  16. Comparing nadir and limb observations of polar mesospheric clouds: The effect of the assumed particle size distribution

    NASA Astrophysics Data System (ADS)

    Bailey, Scott M.; Thomas, Gary E.; Hervig, Mark E.; Lumpe, Jerry D.; Randall, Cora E.; Carstens, Justin N.; Thurairajah, Brentha; Rusch, David W.; Russell, James M.; Gordley, Larry L.

    2015-05-01

    Nadir viewing observations of Polar Mesospheric Clouds (PMCs) from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) spacecraft are compared to Common Volume (CV), limb-viewing observations by the Solar Occultation For Ice Experiment (SOFIE) also on AIM. CIPS makes multiple observations of PMC-scattered UV sunlight from a given location at a variety of geometries and uses the variation of the radiance with scattering angle to determine a cloud albedo, particle size distribution, and Ice Water Content (IWC). SOFIE uses IR solar occultation in 16 channels (0.3-5 μm) to obtain altitude profiles of ice properties including the particle size distribution and IWC in addition to temperature, water vapor abundance, and other environmental parameters. CIPS and SOFIE made CV observations from 2007 to 2009. In order to compare the CV observations from the two instruments, SOFIE observations are used to predict the mean PMC properties observed by CIPS. Initial agreement is poor with SOFIE predicting particle size distributions with systematically smaller mean radii and a factor of two more albedo and IWC than observed by CIPS. We show that significantly improved agreement is obtained if the PMC ice is assumed to contain 0.5% meteoric smoke by mass, in agreement with previous studies. We show that the comparison is further improved if an adjustment is made in the CIPS data processing regarding the removal of Rayleigh scattered sunlight below the clouds. This change has an effect on the CV PMC, but is negligible for most of the observed clouds outside the CV. Finally, we examine the role of the assumed shape of the ice particle size distribution. Both experiments nominally assume the shape is Gaussian with a width parameter roughly half of the mean radius. We analyze modeled ice particle distributions and show that, for the column integrated ice distribution, Log-normal and Exponential distributions better represent the range

  17. Systems for Lung Volume Standardization during Static and Dynamic MDCT-based Quantitative Assessment of Pulmonary Structure and Function

    PubMed Central

    Fuld, Matthew K.; Grout, Randall; Guo, Junfeng; Morgan, John H.; Hoffman, Eric A.

    2013-01-01

    Rationale and Objectives Multidetector-row Computed Tomography (MDCT) has emerged as a tool for quantitative assessment of parenchymal destruction, air trapping (density metrics) and airway remodeling (metrics relating airway wall and lumen geometry) in chronic obstructive pulmonary disease (COPD) and asthma. Critical to the accuracy and interpretability of these MDCT-derived metrics is the assurance that the lungs are scanned during a breath-hold at a standardized volume. Materials and Methods A computer monitored turbine-based flow meter system was developed to control patient breath-holds and facilitate static imaging at fixed percentages of the vital capacity. Due to calibration challenges with gas density changes during multi-breath xenon-CT an alternative system was required. The design incorporated dual rolling seal pistons. Both systems were tested in a laboratory environment and human subject trials. Results The turbine-based system successfully controlled lung volumes in 32/37 subjects, having a linear relationship for CT measured air volume between repeated scans: for all scans, the mean and confidence interval of the differences (scan1-scan2) was −9 ml (−169, 151); for TLC alone 6 ml (−164, 177); for FRC alone, −23 ml (−172, 126). The dual-piston system successfully controlled lung volume in 31/41 subjects. Study failures related largely to subject non-compliance with verbal instruction and gas leaks around the mouthpiece. Conclusion We demonstrate the successful use of a turbine-based system for static lung volume control and demonstrate its inadequacies for dynamic xenon-CT studies. Implementation of a dual-rolling seal spirometer has been shown to adequately control lung volume for multi-breath wash-in xenon-CT studies. These systems coupled with proper patient coaching provide the tools for the use of CT to quantitate regional lung structure and function. The wash-in xenon-CT method for assessing regional lung function, while not

  18. Simulation study comparing exposure matching with regression adjustment in an observational safety setting with group sequential monitoring.

    PubMed

    Stratton, Kelly G; Cook, Andrea J; Jackson, Lisa A; Nelson, Jennifer C

    2015-03-30

    Sequential methods are well established for randomized clinical trials (RCTs), and their use in observational settings has increased with the development of national vaccine and drug safety surveillance systems that monitor large healthcare databases. Observational safety monitoring requires that sequential testing methods be better equipped to incorporate confounder adjustment and accommodate rare adverse events. New methods designed specifically for observational surveillance include a group sequential likelihood ratio test that uses exposure matching and generalized estimating equations approach that involves regression adjustment. However, little is known about the statistical performance of these methods or how they compare to RCT methods in both observational and rare outcome settings. We conducted a simulation study to determine the type I error, power and time-to-surveillance-end of group sequential likelihood ratio test, generalized estimating equations and RCT methods that construct group sequential Lan-DeMets boundaries using data from a matched (group sequential Lan-DeMets-matching) or unmatched regression (group sequential Lan-DeMets-regression) setting. We also compared the methods using data from a multisite vaccine safety study. All methods had acceptable type I error, but regression methods were more powerful, faster at detecting true safety signals and less prone to implementation difficulties with rare events than exposure matching methods. Method performance also depended on the distribution of information and extent of confounding by site. Our results suggest that choice of sequential method, especially the confounder control strategy, is critical in rare event observational settings. These findings provide guidance for choosing methods in this context and, in particular, suggest caution when conducting exposure matching.

  19. Comparison of Airglow from excited O2- and OH-molecules in the global model EMAC compared to SCIAMACHY observations

    NASA Astrophysics Data System (ADS)

    Versick, Stefan; Bender, Stefan; von Savigny, Christian; Sinnhuber, Miriam; Teiser, Georg; Vlasov, Alexey; Zarboo, Amirmahdi

    2016-04-01

    Airglow is a luminous effect mainly in the upper atmosphere (mesosphere and thermosphere). It is caused by various processes. Airglow can be used to derive minor species abundances, to diagnose dynamical phenomena or to derive chemical heating rates (Mlynzcak 1999). Here we concentrate on Airglow from excited O2- and OH-molecules. For the presented study we use the newly developed extended EMAC (3d-CTM) version which includes the thermosphere and reaches upto about 170 km. We extended the chemistry by the relevant processes for airglow. The online-coupled chemistry module MECCA is calculating the different transitions of the excited OH-molecules. In this presentation we weill concentrate on the OH(3-1) transition at a wavelength of 1540 nm. We compare the model results to SCIAMACHY observations during the sudden stratospheric warming in the northern hemisphere winter 2008/09. The model results are qualitatively in good agreement with the observations. EMAC chemistry has also been extended by two excited states of molcular oxygen: O2(1Δ) at 1270 nm and O2(1Σ) at 762 nm. We show first results of the newly developed retrieval for the 762 nm band from SCIAMACHY-observations and compare it to EMAC results.

  20. Observational Study Designs for Comparative Effectiveness Research: An Alternative Approach to Close Evidence Gaps in Head-and-Neck Cancer

    SciTech Connect

    Goulart, Bernardo H.L.; Ramsey, Scott D.; Parvathaneni, Upendra

    2014-01-01

    Comparative effectiveness research (CER) has emerged as an approach to improve quality of care and patient outcomes while reducing healthcare costs by providing evidence to guide healthcare decisions. Randomized controlled trials (RCTs) have represented the ideal study design to support treatment decisions in head-and-neck (H and N) cancers. In RCTs, formal chance (randomization) determines treatment allocation, which prevents selection bias from distorting the measure of treatment effects. Despite this advantage, only a minority of patients qualify for inclusion in H and N RCTs, which limits the validity of their results to the broader H and N cancer patient population seen in clinical practice. Randomized controlled trials often do not address other knowledge gaps in the management of H and N cancer, including treatment comparisons for rare types of H and N cancers, monitoring of rare or late toxicity events (eg, osteoradionecrosis), or in some instances an RCT is simply not feasible. Observational studies, or studies in which treatment allocation occurs independently of investigators' choice or randomization, may address several of these gaps in knowledge, thereby complementing the role of RCTs. This critical review discusses how observational CER studies complement RCTs in generating the evidence to inform healthcare decisions and improve the quality of care and outcomes of H and N cancer patients. Review topics include a balanced discussion about the strengths and limitations of both RCT and observational CER study designs; a brief description of design and analytic techniques to handle selection bias in observational studies; examples of observational studies that inform current clinical practices and management of H and N cancers; and suggestions for relevant CER questions that could be addressed by an observational study design.

  1. Comparing observations of fossil fuel-derived CO2 in California with predictions from bottom-up inventories

    NASA Astrophysics Data System (ADS)

    Graven, H. D.; Lueker, T.; Fischer, M. L.; Guilderson, T. P.; Keeling, R. F.; Brophy, K.; Arnold, T.; Bambha, R.; Callahan, W.; Campbell, J. E.; Frankenberg, C.; Hsu, Y.; Iraci, L. T.; Jeong, S.; Kim, J.; LaFranchi, B. W.; Lehman, S.; Manning, A.; Michelsen, H. A.; Miller, J. B.; Newman, S.; Parazoo, N.; Sloop, C.; Walker, S.; Whelan, M.; Wunch, D.

    2015-12-01

    The US state of California has a progressive climate change mitigation policy, AB-32, enacted in 2006 to reduce greenhouse gas emissions 15% by 2020 and then a further 80% by 2050. Bottom-up inventories indicate California's fossil fuel CO2 emissions are currently about 100 Mt C per year, but different inventories show discrepancies of ±15% in the state-wide total, and some larger discrepancies in various sub-regions of the state. We are developing a top-down framework for investigating fossil fuel and biospheric CO2 fluxes in California using atmospheric observations and models. California has a relatively dense collaborative network of greenhouse gas observations run by several universities, government laboratories and Earth Networks. Using this collaborative network, we conducted three field campaigns in 2014-15 to sample flasks at 10 tower sites across the state. Flasks were analysed for atmospheric CO2 and CO concentrations and for stable isotopes and radiocarbon in CO2. The flask observations of radiocarbon in CO2 allow patterns of fossil fuel-derived and biospheric CO2 to be distinguished at relatively high resolution across the state. We will report initial results from the observations showing regional gradients in fossil fuel-derived CO2 and fluctuations from changing weather patterns. We will compare the observations of fossil fuel-derived CO2 to predictions from several bottom-up inventories and two atmospheric models. Linking the flask data with observations from OCO-2, TCCON, aircraft flights and ground-based in situ analyzers, we will examine the variation in total CO2 and its drivers over California. Further analysis is planned to integrate the data into an inversion framework for fossil fuel and biospheric CO2 fluxes over California.

  2. A comparative analysis of simulated and observed landslide locations triggered by Hurricane Camille in Nelson County, Virginia

    USGS Publications Warehouse

    Morrissey, M.M.; Wieczorek, G.F.; Morgan, B.A.

    2008-01-01

    In 1969, Nelson County, Virginia received up to 71 cm of rain within 12 h starting at 7 p.m. on August 19. The total rainfall from the storm exceeded the 1000-year return period in the region. Several thousands of landslides were induced by rainfall associated with Hurricane Camille causing fatalities and destroying infrastructure. We apply a distributed transient response model for regional slope stability analysis to shallow landslides. Initiation points of over 3000 debris flows and effects of flooding from this storm are applied to the model. Geotechnical data used in the calculations are published data from samples of colluvium. Results from these calculations are compared with field observations such as landslide trigger location and timing of debris flows to assess how well the model predicts the spatial and temporal distribution. of landslide initiation locations. The model predicts many of the initiation locations in areas where debris flows are observed. Copyright ?? 2007 John Wiley & Sons, Ltd.

  3. Comparative analysis of different sensor data (Landsat-TM and MOMS) for earth observation and impact on future sensor development

    NASA Technical Reports Server (NTRS)

    Bodechtel, J.; Zilger, J.; Salomonson, V. V.

    1986-01-01

    The missions of the German Modular Optoelectronic Multispectral Scanner (MOMS) aboard two STS flights demonstrated the feasibility of a novel concept with regard to both technical and scientific objectives. On account of the successful missions, a cooperation was agreed between the German Federal Minister for Research nad Technology and NASA for comparing MOMS observations with the more familiar operational Landsat-TM data over selected test sites, as a means of obtaining some relative measure of performance. This paper summarizes the results obtained and presents the MOMS-02, a further experimental representative of the MOMS program aiming at the realization of an operational system for the mid-nineties.

  4. A new method to compare hourly rainfall between station observations and satellite products over central-eastern China

    NASA Astrophysics Data System (ADS)

    Chen, Haoming; Yu, Rucong; Shen, Yan

    2016-08-01

    This study employs a newly defined regional-rainfall-event (RRE) concept to compare the hourly characteristics of warm-season (May-September) rainfall among rain gauge observations, China merged hourly precipitation analysis (CMPA-Hourly), and two commonly used satellite products (TRMM 3B42 and CMORPH). By considering the rainfall characteristics in a given limited area rather than a single point or grid, this method largely eliminates the differences in rainfall characteristics among different observations or measurements over central-eastern China. The results show that the spatial distribution and diurnal variation of RRE frequency and intensity are quite consistent among different datasets, and the performance of CMPA-Hourly is better than the satellite products when compared with station observations. A regional rainfall coefficient (RRC), which can be used to classify local rain and regional rain, is employed to represent the spatial spread of rainfall in the limited region defining the RRE. It is found that rainfall spread in the selected grid box is more uniform during the nocturnal to morning hours over central-eastern China. The RRC tends to reach its diurnal maximum several hours after the RRE intensity peaks, implying an intermediate transition stage from convective to stratiform rainfall. In the afternoon, the RRC reaches its minimum, implying the dominance of local convections on small spatial scale in those hours, which could cause large differences in rain gauge and satellite observations. Since the RRE method reflects the overall features of rainfall in a limited region rather than at a fixed point or in a single grid, the widely recognized overestimation of afternoon rainfall in satellite products is not obvious, and thus the satellite estimates are more reliable in representing sub-daily variation of rainfall from the RRE perspective. This study proposes a reasonable method to compare satellite products with rain gauge observations on the sub

  5. A Study of The Eastern Mediterranean Hydrology and Circulation By Comparing Observation and High Resolution Numerical Model Results.

    NASA Astrophysics Data System (ADS)

    Alhammoud, B.; Béranger, K.; Mortier, L.; Crépon, M.

    The Eastern Mediterranean hydrology and circulation are studied by comparing the results of a high resolution primitive equation model (described in dedicated session: Béranger et al.) with observations. The model has a horizontal grid mesh of 1/16o and 43 z-levels in the vertical. The model was initialized with the MODB5 climatology and has been forced during 11 years by the daily sea surface fluxes provided by the European Centre for Medium-range Weather Forecasts analysis in a perpetual year mode corresponding to the year March 1998-February 1999. At the end of the run, the numerical model is able to accurately reproduce the major water masses of the Eastern Mediterranean Basin (Levantine Surface Water, modi- fied Atlantic Water, Levantine Intermediate Water, and Eastern Mediterranean Deep Water). Comparisons with the POEM observations reveal good agreement. While the initial conditions of the model are somewhat different from POEM observations, dur- ing the last year of the simulation, we found that the water mass stratification matches that of the observations quite well in the seasonal mean. During the 11 years of simulation, the model drifts slightly in the layers below the thermocline. Nevertheless, many important physical processes were reproduced. One example is that the dispersal of Adriatic Deep Water into the Levantine Basin is rep- resented. In addition, convective activity located in the northern part of the Levantine Basin occurs in Spring as expected. The surface circulation is in agreement with in-situ and satellite observations. Some well known mesoscale features of the upper thermocline circulation are shown. Sea- sonal variability of transports through Sicily, Otranto and Cretan straits are inves- tigated as well. This work was supported by the french MERCATOR project and SHOM.

  6. Comparative analysis of atmosphere temperature variability for Northern Eurasia based on the Reanalysis and in-situ observed data

    NASA Astrophysics Data System (ADS)

    Shulgina, T.; Genina, E.; Gordov, E.; Nikitchuk, K.

    2009-04-01

    At present numerous data archives which include meteorological observations as well as climate processes modeling data are available for Earth Science specialists. Methods of mathematical statistics are widely used for their processing and analysis. In many cases they represent the only way of quantitative assessment of the meteorological and climatic information. Unified set of analysis methods allows us to compare climatic characteristics calculated on the basis of different datasets with the purpose of performing more detailed analysis of climate dynamics for both regional and global levels. The report presents the results of comparative analysis of atmosphere temperature behavior for the Northern Eurasia territory for the period from 1979 to 2004 based on the NCEP/NCAR Reanalysis, NCEP/DOE Reanalysis AMIP II, JMA/CRIEPI JRA-25 Reanalysis, ECMWF ERA-40 Reanalysis data and observation data obtained from meteorological stations of the former Soviet Union. Statistical processing of atmosphere temperature data included analysis of time series homogeneity of climate indices approved by WMO, such as "Number of frost days", "Number of summer days", "Number of icing days", "Number of tropical nights", etc. by means of parametric methods of mathematical statistics (Fisher and Student tests). That allowed conducting comprehensive research of spatio-temporal features of the atmosphere temperature. Analysis of the atmosphere temperature dynamics revealed inhomogeneity of the data obtained for large observation intervals. Particularly, analysis performed for the period 1979 - 2004 showed the significant increase of the number of frost and icing days approximately by 1 day for every 2 years and decrease roughly by 1 day for 2 years for the number of summer days. Also it should be mentioned that the growth period mean temperature have increased by 1.5 - 2° C for the time period being considered. The usage of different Reanalysis datasets in conjunction with in-situ observed

  7. Three-dimensional tropospheric water vapor in coupled climate models compared with observations from the AIRS satellite system

    NASA Astrophysics Data System (ADS)

    Pierce, David W.; Barnett, Tim P.; Fetzer, Eric J.; Gleckler, Peter J.

    2006-11-01

    Changes in the distribution of water vapor in response to anthropogenic forcing will be a major factor determining the warming the Earth experiences over the next century, so it is important to validate climate models' distribution of water vapor. In this work the three-dimensional distribution of specific humidity in state-of-the-art climate models is compared to measurements from the AIRS satellite system. We find the majority of models have a pattern of drier than observed conditions (by 10-25%) in the tropics below 800 hPa, but 25-100% too moist conditions between 300 and 600 hPa, especially in the extra-tropics. Analysis of the accuracy and sampling biases of the AIRS measurements suggests that these differences are due to systematic model errors, which might affect the model-estimated range of climate warming anticipated over the next century.

  8. A novel scheme for detection of diffuse lung disease in MDCT by use of statistical texture features

    NASA Astrophysics Data System (ADS)

    Wang, Jiahui; Li, Feng; Doi, Kunio; Li, Qiang

    2009-02-01

    The successful development of high performance computer-aided-diagnostic systems has potential to assist radiologists in the detection and diagnosis of diffuse lung disease. We developed in this study an automated scheme for the detection of diffuse lung disease on multi-detector computed tomography (MDCT). Our database consisted of 68 CT scans, which included 31 normal and 37 abnormal cases with three kinds of abnormal patterns, i.e., ground glass opacity, reticular, and honeycombing. Two radiologists first selected the CT scans with abnormal patterns based on clinical reports. The areas that included specific abnormal patterns in the selected CT images were then delineated as reference standards by an expert chest radiologist. To detect abnormal cases with diffuse lung disease, the lungs were first segmented from the background in each slice by use of a texture analysis technique, and then divided into contiguous volumes of interest (VOIs) with a 64×64×64 matrix size. For each VOI, we calculated many statistical texture features, including the mean and standard deviation of CT values, features determined from the run length matrix, and features from the co-occurrence matrix. A quadratic classifier was employed for distinguishing between normal and abnormal VOIs by use of a leave-one-case-out validation scheme. A rule-based criterion was employed to further determine whether a case was normal or abnormal. For the detection of abnormal VOIs, our CAD system achieved a sensitivity of 86% and a specificity of 90%. For the detection of abnormal cases, it achieved a sensitivity of 89% and a specificity of 90%. This preliminary study indicates that our CAD system would be useful for the detection of diffuse lung disease.

  9. Radiation dose from MDCT using Monte Carlo simulations: estimating fetal dose due to pulmonary embolism scans accounting for overscan

    NASA Astrophysics Data System (ADS)

    Angel, E.; Wellnitz, C.; Goodsitt, M.; DeMarco, J.; Cagnon, C.; Ghatali, M.; Cody, D.; Stevens, D.; McCollough, C.; Primak, A.; McNitt-Gray, M.

    2007-03-01

    Pregnant women with shortness of breath are increasingly referred for CT Angiography to rule out Pulmonary Embolism (PE). While this exam is typically focused on the lungs, extending scan boundaries and overscan can add to the irradiated volume and have implications on fetal dose. The purpose of this work was to estimate radiation dose to the fetus when various levels of overscan were encountered. Two voxelized models of pregnant patients derived from actual patient anatomy were created based on image data. The models represent an early (< 7 weeks) and late term pregnancy (36 weeks). A previously validated Monte Carlo model of an MDCT scanner was used that takes into account physical details of the scanner. Simulated helical scans used 120 kVp, 4x5 mm beam collimation, pitch 1, and varying beam-off locations (edge of the irradiated volume) were used to represent different protocols plus overscan. Normalized dose (mGy/100mAs) was calculated for each fetus. For the early term and the late term pregnancy models, fetal dose estimates for a standard thoracic PE exam were estimated to be 0.05 and 0.3 mGy/100mAs, respectively, increasing to 9 mGy/100mAs when the beam-off location was extended to encompass the fetus. When performing PE exams to rule out PE in pregnant patients, the beam-off location may have a large effect on fetal dose, especially for late term pregnancies. Careful consideration of ending location of the x-ray beam - and not the end of image data - could result in significant reduction in radiation dose to the fetus.

  10. The distribution of snow black carbon observed in the Arctic and compared to the GISS-PUCCINI model

    NASA Astrophysics Data System (ADS)

    Dou, T.; Xiao, C.; Shindell, D. T.; Liu, J.; Eleftheriadis, K.; Ming, J.; Qin, D.

    2012-09-01

    In this study, we evaluate the ability of the latest NASA GISS composition-climate model, GISS-E2-PUCCINI, to simulate the spatial distribution of snow BC (sBC) in the Arctic relative to present-day observations. Radiative forcing due to BC deposition onto Arctic snow and sea ice is also estimated. Two sets of model simulations are analyzed, where meteorology is linearly relaxed towards National Centers for Environmental Prediction (NCEP) and towards NASA Modern Era Reanalysis for Research and Applications (MERRA) reanalyses. Results indicate that the modeled concentrations of sBC are comparable with present-day observations in and around the Arctic Ocean, except for apparent underestimation at a few sites in the Russian Arctic. That said, the model has some biases in its simulated spatial distribution of BC deposition to the Arctic. The simulations from the two model runs are roughly equal, indicating that discrepancies between model and observations come from other sources. Underestimation of biomass burning emissions in Northern Eurasia may be the main cause of the low biases in the Russian Arctic. Comparisons of modeled aerosol BC (aBC) with long-term surface observations at Barrow, Alert, Zeppelin and Nord stations show significant underestimation in winter and spring concentrations in the Arctic (most significant in Alaska), although the simulated seasonality of aBC has been greatly improved relative to earlier model versions. This is consistent with simulated biases in vertical profiles of aBC, with underestimation in the lower and middle troposphere but overestimation in the upper troposphere and lower stratosphere, suggesting that the wet removal processes in the current model may be too weak or that vertical transport is too rapid, although the simulated BC lifetime seems reasonable. The combination of observations and modeling provides a comprehensive distribution of sBC over the Arctic. On the basis of this distribution, we estimate the decrease in snow

  11. The Distribution of Snow Black Carbon observed in the Arctic and Compared to the GISS-PUCCINI Model

    NASA Technical Reports Server (NTRS)

    Dou, T.; Xiao, C.; Shindell, D. T.; Liu, J.; Eleftheriadis, K.; Ming, J.; Qin, D.

    2012-01-01

    In this study, we evaluate the ability of the latest NASA GISS composition-climate model, GISS-E2- PUCCINI, to simulate the spatial distribution of snow BC (sBC) in the Arctic relative to present-day observations. Radiative forcing due to BC deposition onto Arctic snow and sea ice is also estimated. Two sets of model simulations are analyzed, where meteorology is linearly relaxed towards National Centers for Environmental Prediction (NCEP) and towards NASA Modern Era Reanalysis for Research and Applications (MERRA) reanalyses. Results indicate that the modeled concentrations of sBC are comparable with presentday observations in and around the Arctic Ocean, except for apparent underestimation at a few sites in the Russian Arctic. That said, the model has some biases in its simulated spatial distribution of BC deposition to the Arctic. The simulations from the two model runs are roughly equal, indicating that discrepancies between model and observations come from other sources. Underestimation of biomass burning emissions in Northern Eurasia may be the main cause of the low biases in the Russian Arctic. Comparisons of modeled aerosol BC (aBC) with long-term surface observations at Barrow, Alert, Zeppelin and Nord stations show significant underestimation in winter and spring concentrations in the Arctic (most significant in Alaska), although the simulated seasonality of aBC has been greatly improved relative to earlier model versions. This is consistent with simulated biases in vertical profiles of aBC, with underestimation in the lower and middle troposphere but overestimation in the upper troposphere and lower stratosphere, suggesting that the wet removal processes in the current model may be too weak or that vertical transport is too rapid, although the simulated BC lifetime seems reasonable. The combination of observations and modeling provides a comprehensive distribution of sBC over the Arctic. On the basis of this distribution, we estimate the decrease in snow

  12. Longitudinal changes in structural abnormalities using MDCT in COPD: do the CT measurements of airway wall thickness and small pulmonary vessels change in parallel with emphysematous progression?

    PubMed Central

    Takayanagi, Shin; Kawata, Naoko; Tada, Yuji; Ikari, Jun; Matsuura, Yukiko; Matsuoka, Shin; Matsushita, Shoichiro; Yanagawa, Noriyuki; Kasahara, Yasunori; Tatsumi, Koichiro

    2017-01-01

    Background Recent advances in multidetector computed tomography (MDCT) facilitate acquiring important clinical information for managing patients with COPD. MDCT can detect the loss of lung tissue associated with emphysema as a low-attenuation area (LAA) and the thickness of airways as the wall area percentage (WA%). The percentage of small pulmonary vessels <5 mm2 (% cross-sectional area [CSA] <5) has been recently recognized as a parameter for expressing pulmonary perfusion. We aimed to analyze the longitudinal changes in structural abnormalities using these CT parameters and analyze the effect of exacerbation and smoking cessation on structural changes in COPD patients. Methods We performed pulmonary function tests (PFTs), an MDCT, and a COPD assessment test (CAT) in 58 patients with COPD at the time of their enrollment at the hospital and 2 years later. We analyzed the change in clinical parameters including CT indices and examined the effect of exacerbations and smoking cessation on the structural changes. Results The CAT score and forced expiratory volume in 1 second (FEV1) did not significantly change during the follow-up period. The parameters of emphysematous changes significantly increased. On the other hand, the WA% at the distal airways significantly decreased or tended to decrease, and the %CSA <5 slightly but significantly increased over the same period, especially in ex-smokers. The parameters of emphysematous change were greater in patients with exacerbations and continued to progress even after smoking cessation. In contrast, the WA% and %CSA <5 did not change in proportion to emphysema progression. Conclusion The WA% at the distal bronchi and the %CSA <5 did not change in parallel with parameters of LAA over the same period. We propose that airway disease and vascular remodeling may be reversible to some extent by smoking cessation and appropriate treatment. Optimal management may have a greater effect on pulmonary vascularity and airway disease

  13. Comparing Herschel dust emission structures, magnetic fields observed by Planck, and dynamics: high-latitude star forming cloud L1642

    NASA Astrophysics Data System (ADS)

    Malinen, Johanna

    2016-01-01

    The nearby high-latitude cloud L1642 is one of only two known very high latitude (|b| > 30 deg) clouds actively forming stars. This cloud is a rare example of star formation in isolated conditions, and can reveal important details of star formation in general, e.g., of the effect of magnetic fields. We compare Herschel dust emission structures and magnetic field orientation revealed by Planck polarization maps in L1642, and also combine these with dynamic information from molecular line observations. The high-resolution Herschel data reveal a complex structure including a dense, compressed central blob with elongated extensions, low density striations, "fishbone" like structures with a spine and perpendicular striations, and a spiraling "tail". The Planck polarization data reveal an ordered magnetic field that pervades the cloud and is aligned with the surrounding low density striations. We show that there is a complex interplay between the cloud structure and large scale magnetic fields revealed by Planck polarization data at 10' resolution. This suggests that the magnetic field is closely linked to the formation and evolution of the cloud. We see a clear transition from aligned to perpendicular structures approximately at a column density of NH = 2x10^21 cm-2. We conclude that Planck polarization data revealing the large scale magnetic field orientation can be very useful even when comparing to the finest structures in higher resolution data, e.g. Herschel at ~18" resolution.

  14. Comparative ELM study between the observation by ECEI and linear/nonlinear simulation in the KSTAR plasmas

    NASA Astrophysics Data System (ADS)

    Kim, Minwoo; Park, Hyeon K.; Yun, Gunsu; Lee, Jaehyun; Lee, Jieun; Lee, Woochang; Jardin, Stephen; Xu, X. Q.; Kstar Team

    2015-11-01

    The modeling of the Edge-localized-mode (ELM) should be rigorously pursued for reliable and robust ELM control for steady-state long-pulse H-mode operation in ITER as well as DEMO. In the KSTAR discharge #7328, a linear stability of the ELMs is investigated using M3D-C1 and BOUT + + codes. This is achieved by linear simulation for the n = 8 mode structure of the ELM observed by the KSTAR electron cyclotron emission imaging (ECEI) systems. In the process of analysis, variations due to the plasma equilibrium profiles and transport coefficients on the ELM growth rate are investigated and simulation results with the two codes are compared. The numerical simulations are extended to nonlinear phase of the ELM dynamics, which includes saturation and crash of the modes. Preliminary results of the nonlinear simulations are compared with the measured images especially from the saturation to the crash. This work is supported by NRF of Korea under contract no. NRF-2014M1A7A1A03029865, US DoE by LLNL under contract DE-AC52-07NA27344 and US DoE by PPPL under contract DE-AC02-09CH11466.

  15. Retrospective observational study comparing the international hip dysplasia institute classification with the Tonnis classification of developmental dysplasia of the hip

    PubMed Central

    Miao, Mingyuan; Cai, Haiqing; Hu, Liwei; Wang, Zhigang

    2017-01-01

    Abstract The Tonnis radiographic classification of developmental dysplasia of the hip (DDH) has been widely used. The International Hip Dysplasia Institute (IHDI) classification, a new classification system recently developed by the IHDI, is beginning to be applied to evaluate DDH with the absence of an ossification center. This study aimed to validate its reliability in evaluating DDH with an ossification center and compared the 2 classifications in evaluating all DDH hips. In addition, the prediction values of the 2 classifications on clinical management selection were compared. In total, the pelvic radiographs of 212 DDH patients (318 hips) between the ages of 6 and 48 months admitted to Shanghai Children's Medical Center between 2007 and 2014 were assessed by 3 observers retrospectively using the 2 classifications. Intraobserver and interobserver agreements were evaluated using the kappa method. We also assessed the correlation of the 2 radiographic classifications in terms of treatment selection. In total, 216 hips received closed reduction, 61 hips received open reduction, and 41 hips received pelvic osteotomy. Both classifications showed excellent intraobserver and interobserver reliability. However, the IHDI demonstrated more interobserver reliability, especially for evaluating DDH without an ossification center. Both classifications were found to be relevant in detecting the DDH treatment type (P < 0.01). The Tonnis classification was also relevant, especially for evaluating DDH with an ossification center. The IHDI classification exhibited good practicability in classifying the radiographic severity of DDH compared to the Tonnis classification, particularly in hips without an ossification center. Like the Tonnis classification, the IHDI classification can predict treatment plans. Therefore, the IHDI classification seems to be the upgraded version of the Tonnis classification. PMID:28099350

  16. Punctal plugs versus artificial tears for treating dry eye: a comparative observation of their effects on contrast sensitivity.

    PubMed

    Qiu, Weiqiang; Liu, Ziyuan; Zhang, Zhihong; Ao, Mingxin; Li, Xuemin; Wang, Wei

    2012-01-01

    This study aimed to compare the effects of treatment with punctal plugs versus artificial tears on visual function and tear film stability for dry eye. A total of 56 consecutive eyes of 28 dry eye patients observed at our clinic from May to October in 2009 were divided into two groups. One group (32 eyes of 16 patients) was treated with artificial tears, and punctal plugs were used in the other group (24 eyes of 12 patients). A questionnaire was used in these patients before treatment and was repeated 2 weeks after treatment. Fluorescent staining for tear film break-up time (BUT), the Schirmer test I (STI), and contrast sensitivity was performed at the same time. The questionnaire indicated that all patients complained about the uncomfortable symptoms associated with dry eye. These symptoms were relieved after the application of artificial tears or punctal plugs, and there was no significant difference between these two groups. We found that the corneal fluorescent staining disappeared after treatment. The BUT was improved significantly after treatment in both groups, but the improvement was greater in patients who received punctal plugs than those that received artificial tears. There was no remarkable change in the STI in the artificial tears group, but a significant change was observed in the punctal plugs group. The contrast sensitivities were greatly improved in simulated daylight, night, and glare disability conditions after treatment with artificial tears and punctal plugs. However, the changes in contrast sensitivity did not significantly differ between groups. Both artificial tears and punctal plugs relieved dry eye symptoms, repaired corneal lesions, enhanced tear film stability, and improved contrast sensitivity. Punctal plugs could improve tear film stability and elongate the BUT better than artificial tears.

  17. Utilizing Free and Open Source Software to access, view and compare in situ observations, EO products and model output data

    NASA Astrophysics Data System (ADS)

    Vines, Aleksander; Hamre, Torill; Lygre, Kjetil

    2014-05-01

    The GreenSeas project (Development of global plankton data base and model system for eco-climate early warning) aims to advance the knowledge and predictive capacities of how marine ecosystems will respond to global change. A main task has been to set up a data delivery and monitoring core service following the open and free data access policy implemented in the Global Monitoring for the Environment and Security (GMES) programme. The aim is to ensure open and free access to historical plankton data, new data (EO products and in situ measurements), model data (including estimates of simulation error) and biological, environmental and climatic indicators to a range of stakeholders, such as scientists, policy makers and environmental managers. To this end, we have developed a geo-spatial database of both historical and new in situ physical, biological and chemical parameters for the Southern Ocean, Atlantic, Nordic Seas and the Arctic, and organized related satellite-derived quantities and model forecasts in a joint geo-spatial repository. For easy access to these data, we have implemented a web-based GIS (Geographical Information Systems) where observed, derived and forcasted parameters can be searched, displayed, compared and exported. Model forecasts can also be uploaded dynamically to the system, to allow modelers to quickly compare their results with available in situ and satellite observations. We have implemented the web-based GIS(Geographical Information Systems) system based on free and open source technologies: Thredds Data Server, ncWMS, GeoServer, OpenLayers, PostGIS, Liferay, Apache Tomcat, PRTree, NetCDF-Java, json-simple, Geotoolkit, Highcharts, GeoExt, MapFish, FileSaver, jQuery, jstree and qUnit. We also wanted to used open standards to communicate between the different services and we use WMS, WFS, netCDF, GML, OPeNDAP, JSON, and SLD. The main advantage we got from using FOSS was that we did not have to invent the wheel all over again, but could use

  18. Increased serum concentrations of circulating glycocalyx components in HELLP syndrome compared to healthy pregnancy: an observational study.

    PubMed

    Hofmann-Kiefer, Klaus F; Knabl, J; Martinoff, N; Schiessl, B; Conzen, P; Rehm, M; Becker, B F; Chappell, D

    2013-03-01

    Severe inflammation has been shown to induce a shedding of the endothelial glycocalyx (EGX). Inflammatory cytokines, such as tumor necrosis factor α (TNF-α), impede the thickness of the EGX. While a controlled inflammatory reaction occurs already in normal pregnancy, women with hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome had an exaggerated inflammatory response. This study investigates the shedding of the glycocalyx during normal pregnancy and in women with HELLP syndrome. Glycocalyx components (syndecan 1, heparan sulfate, and hyaluronic acid) were measured in serum of healthy women throughout pregnancy (4 time points, n = 26), in women with HELLP syndrome (n = 17) before delivery and in nonpregnant volunteers (n = 10). Serum concentrations of TNF-α and soluble TNF-α receptors (sTNF-Rs) were assessed once in all 3 groups. Syndecan 1 serum concentrations constantly rose throughout normal pregnancy. Immediately before delivery, a 159-fold increase was measured compared to nonpregnant controls (P < .01). Even higher amounts were observed in patients with HELLP prior to delivery (median 12 252 ng/mL) compared to healthy women matched by gestational age (median 5943 ng/mL; P < .01). Relevantly, increased serum levels of heparan sulfate, hyaluronic acid, and sTNF-Rs were only detected in patients with HELLP (P < .01). These findings suggest that considerable amounts of syndecan 1 are released into maternal blood during uncomplicated pregnancy. The HELLP syndrome is associated with an even more pronounced shedding of glycocalyx components. The maternal vasculature as well as the placenta has to be discussed as a possible origin of circulating glycocalyx components.

  19. The 2014 Lake Askja rockslide tsunami - optimization of landslide parameters comparing numerical simulations with observed run-up

    NASA Astrophysics Data System (ADS)

    Sif Gylfadóttir, Sigríður; Kim, Jihwan; Kristinn Helgason, Jón; Brynjólfsson, Sveinn; Höskuldsson, Ármann; Jóhannesson, Tómas; Bonnevie Harbitz, Carl; Løvholt, Finn

    2016-04-01

    The Askja central volcano is located in the Northern Volcanic Zone of Iceland. Within the main caldera an inner caldera was formed in an eruption in 1875 and over the next 40 years it gradually subsided and filled up with water, forming Lake Askja. A large rockslide was released from the Southeast margin of the inner caldera into Lake Askja on 21 July 2014. The release zone was located from 150 m to 350 m above the water level and measured 800 m across. The volume of the rockslide is estimated to have been 15-30 million m3, of which 10.5 million m3 was deposited in the lake, raising the water level by almost a meter. The rockslide caused a large tsunami that traveled across the lake, and inundated the shores around the entire lake after 1-2 minutes. The vertical run-up varied typically between 10-40 m, but in some locations close to the impact area it ranged up to 70 m. Lake Askja is a popular destination visited by tens of thousands of tourists every year but as luck would have it, the event occurred near midnight when no one was in the area. Field surveys conducted in the months following the event resulted in an extensive dataset. The dataset contains e.g. maximum inundation, high-resolution digital elevation model of the entire inner caldera, as well as a high resolution bathymetry of the lake displaying the landslide deposits. Using these data, a numerical model of the Lake Askja landslide and tsunami was developed using GeoClaw, a software package for numerical analysis of geophysical flow problems. Both the shallow water version and an extension of GeoClaw that includes dispersion, was employed to simulate the wave generation, propagation, and run-up due to the rockslide plunging into the lake. The rockslide was modeled as a block that was allowed to stretch during run-out after entering the lake. An optimization approach was adopted to constrain the landslide parameters through inverse modeling by comparing the calculated inundation with the observed run

  20. Efficacy and Effects of Parenteral Pethidine or Meptazinol and Regional Analgesia for Pain Relief during Delivery. A Comparative Observational Study

    PubMed Central

    Singer, J.; Jank, A.; Amara, S.; Stepan, P. D. H.; Kaisers, U.; Hoehne, C.

    2016-01-01

    Background: Peripartum anesthesia may consist of parenteral opioids and/or regional analgesia. There is only limited data in the literature comparing both methods in daily obstetric practice. This observational study investigated the opioids pethidine and meptazinol as well as regional analgesics with regard to their administration, efficacy, side effects and subjective maternal satisfaction with therapy. The rates of secondary regional analgesia administration after administration of the respective opioid served as a means of evaluating treatment. Methods: This study collected data on pain management during vaginal delivery in a German university hospital over a twelve month period. Severity of pain was measured intrapartum using a numerical rating scale. Maternal, neonatal and delivery-related data were obtained postpartum from the clinical records and from the mothers using a questionnaire. Results: The study is based on data obtained from 449 deliveries. Pain relief achieved by the administration of pethidine and meptazinol was similarly low; maternal satisfaction with the respective therapy was high. Meptazinol was usually administered intravenously (83 % vs. 6 %; p < 0.001), repeatedly (27 % vs. 6 %; p < 0.001) and closer to the birth (1.9 ± 2.7 h vs. 2.6 ± 2.8 h; p < 0.05) compared to pethidine. Secondary regional analgesia was more common after the administration of pethidine (16 % vs. 8 %; p < 0.05). Regional analgesia resulted in greater pain relief compared to opioid therapy (78 % vs. 24 % after 30 min; p < 0.001) and was associated with longer times to delivery (7.6 ± 2.5 h vs. 5.7 ± 2.5 h; p < 0.001) and higher levels of maternal satisfaction with therapy (6.1 ± 1.2 vs. 4.8 ± 1.6 on a 7-point scale; p < 0.001). Conclusion: In daily clinical practice, meptazinol can be adapted more readily to changes during birth and requires less secondary analgesia. Regional neuraxial

  1. A web portal for accessing, viewing and comparing in situ observations, EO products and model output data

    NASA Astrophysics Data System (ADS)

    Vines, Aleksander; Hamre, Torill; Lygre, Kjetil

    2014-05-01

    The GreenSeas project (Development of global plankton data base and model system for eco-climate early warning) aims to advance the knowledge and predictive capacities of how marine ecosystems will respond to global change. A main task has been to set up a data delivery and monitoring core service following the open and free data access policy implemented in the Global Monitoring for the Environment and Security (GMES) programme. A key feature of the system is its ability to compare data from different datasets, including an option to upload one's own netCDF files. The user can for example search in an in situ database for different variables (like temperature, salinity, different elements, light, specific plankton types or rate measurements) with different criteria (bounding box, date/time, depth, Longhurst region, cruise/transect) and compare the data with model data. The user can choose model data or Earth observation data from a list, or upload his/her own netCDF files to use in the comparison. The data can be visualized on a map, as graphs and plots (e.g. time series and property-property plots), or downloaded in various formats. The aim is to ensure open and free access to historical plankton data, new data (EO products and in situ measurements), model data (including estimates of simulation error) and biological, environmental and climatic indicators to a range of stakeholders, such as scientists, policy makers and environmental managers. We have implemented a web-based GIS(Geographical Information Systems) system and want to demonstrate the use of this. The tool is designed for a wide range of users: Novice users, who want a simple way to be able to get basic information about the current state of the marine planktonic ecosystem by utilizing predefined queries and comparisons with models. Intermediate level users who want to explore the database on their own and customize the prefedined setups. Advanced users who want to perform complex queries and

  2. The Dynamic Atmospheres of Mira Stars: Comparing the CODEX Models to PTI Time Series Observations of TU Andromedae

    NASA Astrophysics Data System (ADS)

    Hillen, M.; Verhoelst, T.; Degroote, P.; Acke, B.; Van Winckel, H.

    2015-08-01

    We present our already-published evaluation of the effectiveness of the CODEX models, released in 2011, in representing the atmospheres of M-type Mira variables. We present a high-precision interferometric K-band time series of TU And, consisting of 50 nights that cover eight consecutive pulsation cycles. At each phase, the flux at 2.2μm was obtained, along with the spectral shape and visibility points in five channels across the K band. We show a comparison between these data and the dynamical self-excited CODEX model which gives the closest match in stellar parameters yet available. Both the spectrum and the visibilities are consistently reproduced around visual minimum phases. Near the maximum phases, however, the current models predict a photosphere that is too hot and compact, surrounded by an extended atmosphere that lacks H2O opacity, compared to the observations. A better coverage in the model parameter space is needed to make firm conclusions as to the cause of the discrepancies. In the case of TU And, the discrepancy might be lifted by adopting a lower value of the mixing length parameter combined with an increased stellar mass and/or a decreased metallicity.

  3. Comparative observations of learning engagement by students with developmental disabilities using an Ipad and computer: a pilot study.

    PubMed

    Arthanat, Sajay; Curtin, Christine; Knotak, David

    2013-01-01

    This study examined the use of the Apple iPad for learning by children with developmental disabilities (DD), including those on the autism spectrum. A single case design was used to record the participation of four students with DD when taught with their standard computer at baseline, followed by the introduction of the iPad. A six-component participation scale was developed to quantify observations of these students during the learning sessions. Visual analysis of data indicated no differences in participation with the iPad as compared to the computer for three of the four subjects. One subject appeared to have notably higher participation with the iPad. Individual variations were identified in each student along with some common concerns with attention, task persistence, and goal directed behavior with use of the iPad. Student academic scores improved during the course of iPad use. Nevertheless, the findings drawn from this pilot study do not justify the use of the iPad over the computer (and vice versa) for achieving academic goals in students with DD. The need to document best practices and barriers in use of emerging touch-tablet devices to support individualized education was clearly evident.

  4. Oscillatory fluid flow in deformable tubes: Implications for pore-scale hydromechanics from comparing experimental observations with theoretical predictions.

    PubMed

    Kurzeja, Patrick; Steeb, Holger; Strutz, Marc A; Renner, Jörg

    2016-12-01

    Oscillatory flow of four fluids (air, water, two aqueous sodium-tungstate solutions) was excited at frequencies up to 250 Hz in tubes of two materials (steel, silicone) covering a wide range in length, diameter, and thickness. The hydrodynamical response was characterized by phase shift and amplitude ratio between pressures in an upstream (pressure excitation) and a downstream reservoir connected by the tubes. The resulting standing flow waves reflect viscosity-controlled diffusive behavior and inertia-controlled wave behavior for oscillation frequencies relatively low and high compared to Biot's critical frequency, respectively. Rigid-tube theories correspond well with the experimental results for steel tubes filled with air or water. The wave modes observed for silicone tubes filled with the rather incompressible liquids or air, however, require accounting for the solid's shear and bulk modulus to correctly predict speed of pressure propagation and deformation mode. The shear mode may be responsible for significant macroscopic attenuation in porous materials with effective frame-shear moduli lower than the bulk modulus of the pore fluid. Despite notable effects of the ratio of densities and of acoustic and shear velocity of fluid and solid, Biot's frequency remains an approximate indicator of the transition from the viscosity to the inertia controlled regime.

  5. Comparative Analysis of Gas Halos in High Redshift Galaxies: Observations vs Λ-CDM Simluations with Feedback

    NASA Astrophysics Data System (ADS)

    Churchill, Christopher W.; Klypin, A.; Ceverino, D.; Kacprzak, G. G.

    2007-12-01

    Analysis of mock quasar spectra of metal absorption lines in the proximity of formed galaxies in cosmological simulation is a highly promising approach for interpreting the efficiency with which gas is converted into stars in galaxies, the mechanisms of gas inflow in the context of the cosmic web, and the star-gas feedback processes in galaxies. We are undertaking a wholesale approach to use powerful Λ-CDM simulations to interpret high-quality absorption line data (HIRES/UVES) and high-quality galaxy imaging data (HST) for inferring the interplay between galaxies and metal enriched gas in the vicinity of galaxies (few hundred kpc). The simulations are performed using the Eulerian Gasdynamics plus N-body Adaptive Refinement Tree (ART) code, which has gas cell resolutions of 20-50 pc. Physical processes implemented in the code include radiative cooling, star formation, metal enrichment and thermal feedback due to type II and type Ia supernovae. We quantitatively compare the observed and simulated spatial and kinematic distribution of HI, MgII, CIV, and OVI absorption lines over a range of impact parameters as a function of redshift, and discuss key insights for interpreting the underlying temperature, density, and ionization structure of the halo/cosmic-web interface, and the influence of galaxies on its chemical enrichment. Disparities between the simulations and the statistical cross sections and velocity spreads of the absorption line data in turn provide powerful constraints on the galaxy feedback recipes, which we quantitatively examine.

  6. Observed & Modeled Changes in the Onset of Spring: A Preliminary Comparative Analysis by Geographic Regions of the USA

    NASA Astrophysics Data System (ADS)

    Enquist, C.

    2012-12-01

    Phenology, the study of seasonal life cycle events in plants and animals, is a well-recognized indicator of climate change impacts on people and nature. Models, experiments, and observational studies show changes in plant and animal phenology as a function of environmental change. Current research aims to improve our understanding of changes by enhancing existing models, analyzing observations, synthesizing previous research, and comparing outputs. Local to regional climatology is a critical driver of phenological variation of organisms across scales. Because plants respond to the cumulative effects of daily weather over an extended period, timing of life cycle events are effective integrators of climate data. One specific measure, leaf emergence, is particularly important because it often shows a strong response to temperature change, and is crucial for assessment of processes related to start and duration of the growing season. Schwartz et al. (2006) developed a suite of models (the "Spring Indices") linking plant development from historical data from leafing and flowering of cloned lilac and honeysuckle with basic climatic drivers to monitor changes related to the start of the spring growing season. These models can be generated at any location that has daily max-min temperature time series. The new version of these models is called the "Extended Spring Indices," or SI-x (Schwartz et al. in press). The SI-x model output (first leaf date and first bloom date) are produced similarly to the original models (SI-o), but do not incorporate accumulated chilling hours; rather energy accumulation starts for all stations on January 1. This change extends the locations SI model output can be generated into the sub-tropics, allowing full coverage of the conterminous USA. Both SI model versions are highly correlated, with mean bias and mean absolute differences around two days or less, and a similar bias and absolute errors when compared to cloned lilac data. To

  7. Criteria for establishing shielding of multi-detector computed tomography (MDCT) rooms.

    PubMed

    Verdun, F R; Aroua, A; Baechler, S; Schmidt, S; Trueb, P R; Bochud, F O

    2010-01-01

    The aim of this work is to compare two methods used for determining the proper shielding of computed tomography (CT) rooms while considering recent technological advances in CT scanners. The approaches of the German Institute for Standardisation and the US National Council on Radiation Protection and Measurements were compared and a series of radiation measurements were performed in several CT rooms at the Lausanne University Hospital. The following three-step procedure is proposed for assuring sufficient shielding of rooms hosting new CT units with spiral mode acquisition and various X-ray beam collimation widths: (1) calculate the ambient equivalent dose for a representative average weekly dose length product at the position where shielding is required; (2) from the maximum permissible weekly dose at the location of interest, calculate the transmission factor F that must be taken to ensure proper shielding and (3) convert the transmission factor into a thickness of lead shielding. A similar approach could be adopted to use when designing shielding for fluoroscopy rooms, where the basic quantity would be the dose area product instead of the load of current (milliampere-minute).

  8. Monte Carlo simulations in multi-detector CT (MDCT) for two PET/CT scanner models using MASH and FASH adult phantoms

    NASA Astrophysics Data System (ADS)

    Belinato, W.; Santos, W. S.; Paschoal, C. M. M.; Souza, D. N.

    2015-06-01

    The combination of positron emission tomography (PET) and computed tomography (CT) has been extensively used in oncology for diagnosis and staging of tumors, radiotherapy planning and follow-up of patients with cancer, as well as in cardiology and neurology. This study determines by the Monte Carlo method the internal organ dose deposition for computational phantoms created by multidetector CT (MDCT) beams of two PET/CT devices operating with different parameters. The different MDCT beam parameters were largely related to the total filtration that provides a beam energetic change inside the gantry. This parameter was determined experimentally with the Accu-Gold Radcal measurement system. The experimental values of the total filtration were included in the simulations of two MCNPX code scenarios. The absorbed organ doses obtained in MASH and FASH phantoms indicate that bowtie filter geometry and the energy of the X-ray beam have significant influence on the results, although this influence can be compensated by adjusting other variables such as the tube current-time product (mAs) and pitch during PET/CT procedures.

  9. Celiac Axis, Common Hepatic and Hepatic Artery Variants as Evidenced on MDCT Angiography in South Indian Population

    PubMed Central

    Parthasarathy, Ramesh

    2016-01-01

    Introduction With the increase in the hepatobiliary, pancreatic surgeries and liver transplantation, being aware of the anatomic variations of the celiac axis and the hepatic arteries is of paramount importance. Aim To illustrate the normal anatomy and variants of the celiac axis and the hepatic arteries with multidetector computed tomographic (MDCT) angiography in South Indian population and determine the potential variations in the celiac axis anatomy and the hepatic arteries, thus assisting the hepatobiliary surgeon and the interventional radiologist in avoiding iatrogenic injury to the arteries. Materials and Methods Two hundred patients undergoing abdominal CT angiography from July 2014 till July 2015 were retrospectively studied for hepatic arterial and celiac axis anatomical variation. The anatomic variations in our study were correlated with other studies. Results The celiac axis (CA) and the hepatic artery (HA) variations were analysed as per criteria laid by Song et al., and Michel. Out of 15 possible CA variations, 5 types of celiac artery variations were seen in 14 patients. A normal CA was seen in 179(89.5%) patients of the 200 patients. In the remaining 7 patients, the CA anatomy was classified as ambiguous since there was separate origin of the right and left hepatic arteries from the CA with absent common hepatic artery (CHA). The CHA originated normally from the celiac axis in 94% of the cases. Variation of CHA origin was seen in 5 patients. Normal HA anatomy was seen in 114 (57%) patients. Variation in HA anatomy was seen in 86 (43%) patients. Origin of the right hepatic artery (RHA) from the hepatic artery proper was seen in 182 (91%) patients and replaced origin of RHA from the superior mesenteric artery (SMA) was seen in 18 (9%) of the cases. Accessory RHA was seen in 7(3.5%) patients. The left hepatic artery (LHA) originated from the hepatic artery proper in 186 (93%) patients and replaced origin of LHA from the left gastric artery (LGA) was

  10. Seismic Network Performance Estimation: Comparing Predictions of Magnitude of Completeness and Location Accuracy to Observations from an Earthquake Catalogue

    NASA Astrophysics Data System (ADS)

    Spriggs, N.; Greig, D. W.; Ackerley, N. J.

    2014-12-01

    The design of seismic networks for the monitoring of induced seismicity is of critical importance. The recent introduction of regulations in various locations around the world (with more upcoming) has created a need for a priori confirmation that certain performance standards are met. We develop a tool to assess two key measures of network performance without an earthquake catalogue: magnitude of completeness and location accuracy. Site noise measurements are taken at existing seismic stations or as part of a noise survey. We then interpolate between measured values to determine a noise map for the entire region. The site noise is then summed with the instrument noise to determine the effective station noise at each of the proposed station locations. Location accuracy is evaluated by generating a covariance matrix that represents the error ellipsoid from the travel time derivatives (Peters and Crosson, 1972). To determine the magnitude of completeness we assume isotropic radiation and mandate a minimum signal to noise ratio for detection. For every gridpoint, we compute the Brune spectra for synthetic events and iterate to determine the smallest magnitude event that can be detected by at least four stations. We apply this methodology to an example network. We predict the magnitude of completeness and the location accuracy and compare the predicted values to observed values generated from the existing earthquake catalogue for the network. We discuss the effects of hypothetical station additions and removals on network performance to simulate network expansions and station failures. The ability to predict hypothetical station performance allows for the optimization of seismic network design and enables prediction of network performance even for a purely hypothetical seismic network. This allows the operators of networks for induced seismicity monitoring to be confident that performance criteria are met from day one of operations.

  11. Evaluation of Lung MDCT Nodule Annotation Across Radiologists and Methods1

    PubMed Central

    Meyer, Charles R.; Johnson, Timothy D.; McLennan, Geoffrey; Aberle, Denise R.; Kazerooni, Ella A.; MacMahon, Heber; Mullan, Brian F.; Yankelevitz, David F.; van Beek, Edwin J. R.; Armato, Samuel G.; McNitt-Gray, Michael F.; Reeves, Anthony P.; Gur, David; Henschke, Claudia I.; Hoffman, Eric A.; Bland, Peyton H.; Laderach, Gary; Pais, Richie; Qing, David; Piker, Chris; Guo, Junfeng; Starkey, Adam; Max, Daniel; Croft, Barbara Y.; Clarke, Laurence P.

    2007-01-01

    Rationale and Objectives Integral to the mission of the National Institutes of Health–sponsored Lung Imaging Database Consortium is the accurate definition of the spatial location of pulmonary nodules. Because the majority of small lung nodules are not resected, a reference standard from histopathology is generally unavailable. Thus assessing the source of variability in defining the spatial location of lung nodules by expert radiologists using different software tools as an alternative form of truth is necessary. Materials and Methods The relative differences in performance of six radiologists each applying three annotation methods to the task of defining the spatial extent of 23 different lung nodules were evaluated. The variability of radiologists’ spatial definitions for a nodule was measured using both volumes and probability maps (p-map). Results were analyzed using a linear mixed-effects model that included nested random effects. Results Across the combination of all nodules, volume and p-map model parameters were found to be significant at P < .05 for all methods, all radiologists, and all second-order interactions except one. The radiologist and methods variables accounted for 15% and 3.5% of the total p-map variance, respectively, and 40.4% and 31.1% of the total volume variance, respectively. Conclusion Radiologists represent the major source of variance as compared with drawing tools independent of drawing metric used. Although the random noise component is larger for the p-map analysis than for volume estimation, the p-map analysis appears to have more power to detect differences in radiologist-method combinations. The standard deviation of the volume measurement task appears to be proportional to nodule volume. PMID:16979075

  12. The spectrum of facial fractures in motor vehicle accidents: an MDCT study of 374 patients.

    PubMed

    Peltola, Elina M; Koivikko, Mika P; Koskinen, Seppo K

    2014-04-01

    Road traffic accidents are a major health problem worldwide resulting frequently in maxillofacial injuries. The purpose of the study was to assess the incidence and spectrum of facial fractures in patients involved in a motor vehicle accident (MVA). Using picture archiving and communication system, all requests for suspected facial trauma were retrieved during a 62-month period; 374 met the inclusion criteria. Two researchers interpreted the multidetector computed tomography images by consensus. The motor vehicles involved were divided into two groups: those involving a passenger car or a larger vehicle and those involving a motorized two-wheeler. Furthermore, the motor vehicle accidents were divided into collisions and run-off-road accidents. Of the 374 patients (aged 15-80, mean 34), 271 (72 %) were male and 103 (28 %) female. Of all patients, 262 (70 %) had a facial or skull base fracture; of these, multiple separate fractures were present in 56 %. Nasal fractures were the most common fractures followed by orbital, skull base, and maxillary fractures. Frontal bone, LeFort, and zygomatic arch fractures were always accompanied by other fractures. Fractures were more frequent in the group of collisions compared with run-off-road accidents. In the two-wheeled group, only 15 % did not have facial or skull base fractures. Fractures often occur in multitudes as 39 % of all patients have multiple facial or skull bone fractures, and thus, emergency radiologists should be familiar with the complexity of the injuries. Negative clear sinus sign and low-energy sentinel injuries should be trusted as indications of undetected injuries in MVA victims.

  13. Controversies about effects of low-kilovoltage MDCT acquisition on Agatston calcium scoring.

    PubMed

    Deprez, Fabrice C; Vlassenbroek, Alain; Ghaye, Benoît; Raaijmakers, Rolf; Coche, Emmanuel

    2013-01-01

    Recent articles have advocated the possibility of obtaining Agatston coronary calcium scoring at 100 kVp by using a single adapted elevated calcium threshold. To evaluate the influence of kilovoltage potential protocols on the Agatston score, we acquired successive scans of a calcium scoring phantom at 4 levels of kilovoltage potential (80, 100, 120, and 140 kVp, 55 mAs) and measured semiautomatically the individual and the total Agatston score of 6 inserts (of 5-mm and 3-mm diameter) containing hydroxyapatite at different concentrations (800, 400, 200 mg/cm(3)). Our results showed that Agatston scores obtained at various low-kilovoltage potential protocols can be highly overestimated in some particular cases. At 80 kVp, for example, mean measured Agatston score was multiplied by a factor from 1.06 (5-mm highest density insert) to 2.67 (3-mm lowest density insert) compared with the Agatston scores performed at 120 kVp. Indeed in the one hand, reducing kilovoltage potential in multidetector CT acquisitions increase the CT density of coronary calcifications that can be measured on the reconstructed images. On the other hand, Agatston score is a multi-threshold measurement (with a step weighting function). Consequently low kilovoltage potential can lead to overweight some calcifications scores. For these reasons, Agatston score with low kilovoltage potential acquisition cannot be reliably adapted by a unique recalibration of the standard calcium attenuation threshold of 130 HU and requires a standardized CT acquisition protocol at 120 kVp. Alternatives to performing low-dose coronary artery calcium scans are either using coronary calcium scans with reduced tube current (low mAs) at 120 kVp with the iterative reconstructions or using mass/volume scoring (not influenced by kilovoltage potential variations). Finally, we emphasized that incorrect Agatston score evaluation may have important clinical, financial, and health care implications.

  14. COMPARATIVE STUDY OF SINGLE AND MULTISLICE COMPUTED TOMOGRAPHY FOR ASSESSMENT OF THE MANDIBULAR CANAL

    PubMed Central

    Paes, Adriana da Silva Ferreira; Moreira, Carla Ruffeil; Sales, Marcelo Augusto Oliveira; Cavalcanti, Marcelo Gusmão Paraíso

    2007-01-01

    Objective: The purpose of this study was to evaluate the accuracy of relative measurements from the roof of the mandibular canal to the alveolar crest in multislice (multidetector) computed tomography (MDCT) and single-slice computed tomography (SSCT). Material and Methods: The sample consisted of 26 printed CT films (7 SSCT and 19 MDCT) from the files of the LABI-3D (3D Imaging Laboratory) of the School of Dentistry of the University of São Paulo (FOUSP), which had been acquired using different protocols. Two observers analyzed in a randomized and independent order a series of 22 oblique CT reconstructions of each patient. Each observer analyzed the CT scans twice. The length of the mandibular canal and the distance between the mandibular canal roof and the crest of the alveolar ridge were obtained. Dahlberg test was used for statistical analysis. Results: The mean error found for the mandibular canal length measurements obtained from SSCT was 0.53 mm in the interobserver analysis, and 0.38 mm for both observers. On MDCT images, the mean error was 0.0 mm in the interobserver analysis, and 0.0 and 0.23 mm in the intraobserver analysis. Regarding the distance between the mandibular canal roof and the alveolar bone crest, the SSCT images showed a mean error of 1.16 mm in the interobserver analysis and 0.66 and 0.59 mm in the intraobserver analysis. In the MDCT images, the mean error was 0.72 mm in the interobserver analysis and 0.50 and 0.54 mm in the intraobserver analysis. Conclusion: Multislice CT was demonstrated a more accurate method and demonstrated high reproducibility in the analysis of important anatomical landmarks for planning of mandibular dental implants, namely the mandibular canal pathway and alveolar crest height. PMID:19089133

  15. Comparing the strengths and weaknesses of observational and experimental studies using a postmarketing surveillance study as a protypic example.

    PubMed

    Furst, D E

    1993-10-01

    A recent prospective, observational study in rheumatoid arthritis patients indicated that the addition of hydroxychloroquine to either aspirin or methotrexate therapy decreased the incidence of hepatic enzyme abnormalities. This interesting finding is of potential clinical importance, but its validity needs to be examined in terms of the potential confounders inherent in observational studies. Although one of the study's strengths is its derivation from "real-life" data, some potential confounders that might weaken the data include a need to examine whether any scientific rationale can be discerned for the observation; examination of control-case matching (issues of randomization and baseline disease characteristics); the potential for attribution bias; data-collection methods (prospective versus retrospective, uniform versus chart review); and equivalency of treatment protocols, dosing regimens, and concomitant medications. Potential scientific rationale exists for the observed interaction, and data collection is both uniform and prospective. These strengths are confounded by the inevitable lack of randomization in observational studies, the potential for differences in baseline disease characteristics, attribution bias, a lack of controlled dosing regimens and treatment protocols, and an assumption that all nonsteroid antiinflammatory drugs are alike (which is not true). On balance, the hypothesis generated by these data is compelling enough to deserve further testing in both observational and experimental settings.

  16. Comparative Analysis of Five Observational Audit Tools to Assess the Physical Environment of Parks for Physical Activity, 2016

    PubMed Central

    Maddock, Jay E.

    2016-01-01

    We reviewed prominent audit tools used to assess the physical environment of parks and their potential to promote physical activity. To accomplish this, we manually searched the Active Living Research website (http://www.activelivingresearch.com) for published observational audit tools that evaluate the physical environment of parks, and we reviewed park audit tools used in studies included in a systematic review of observational park-based physical activity studies. We identified 5 observational audit tools for review: Bedimo-Rung Assessment Tool–Direct Observation (BRAT-DO), Community Park Audit Tool (CPAT), Environmental Assessment of Public Recreation Spaces (EAPRS) tool, Physical Activity Resource Assessment (PARA), and Quality of Public Open Space Tool (POST). All 5 tools have established inter-rater reliability estimates ranging from moderate to good. However, BRAT-DO is the only tool with published validity. We found substantial heterogeneity among the 5 in length, format, intended users, and specific items assessed. Researchers, practitioners, or community coalition members should review the goal of their specific project and match their goal with the most appropriate tool and the people who will be using it. PMID:27978411

  17. Combined observations of meteors by image-orthicon television camera and multi-station radar. [to compare ionization with luminosity

    NASA Technical Reports Server (NTRS)

    Cook, A. F.; Forti, G.; Mccrosky, R. E.; Posen, A.; Southworth, R. B.; Williams, J. T.

    1973-01-01

    Observations from multiple sites of a radar network and by television of 29 individual meteors from February 1969 through June 1970 are reported. Only 12 of the meteors did not appear to fragment over all the observed portion of their trajectories. From these 12, the relation for the radar magnitude to the panchromatic absolute magnitude was found in terms of velocity of the meteor. A very tentative fit to the data on the duration of long enduring echoes versus visual absolute magnitude is made. The exponential decay characteristics of the later parts of several of the light curves are pointed out as possible evidence of mutual coalescence of droplets into which the meteoroid has completely broken.

  18. Near-Infrared Spectra of IC 59/63 and NGC 1535: Comparing Infrared and Ultraviolet Observations of H2

    NASA Astrophysics Data System (ADS)

    Luhman, M. L.; Luhman, K. L.; Benedict, T.; Jaffe, D. T.; Fischer, J.

    1997-05-01

    We present observations of near-infrared H2 line emission toward the reflection/emission nebulae, IC 59 and IC 63, and the planetary nebula, NGC 1535. Each source has been observed previously in the ultraviolet, where H2 was detected in emission toward IC 63 and in absorption toward NGC 1535. In IC 63, we have detected the 1.601 μm v = 6-4 Q(1), 2.121 μm v = 1-0 S(1), and 2.247 μm v = 2-1 S(1) lines of H2 arising from a near-infrared fluorescent cascade following ultraviolet continuum pumping. The detection marks the first time that both infrared and ultraviolet portions of the H2 fluorescent cascade have been measured in a region exposed to far-ultraviolet continuum photons. Furthermore, we also report 1-0 S(1) and 2-1 S(1) fluorescent emission toward IC 59, a source previously thought to display no H2 fluorescence and considered devoid of molecules based on ultraviolet and CO observations. Toward NGC 1535, we find no H2 emission in the near-infrared, in spite of the reported ultraviolet H2 absorption.

  19. A comparative study of microwave radiometer observations over snowfields with radiative transfer model calculations. [for water runoff estimation

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Shiue, J. C.

    1979-01-01

    Truck mounted microwave instrumentation was used to study the microwave emission characteristics of the Colorado Rocky Mountain snowpack in the vicinity of Fraser, Colorado during the winter of 1978. The spectral signatures of 5.0, 10.7, 18, and 37 GHz radiometers with dual polarization were used to measure the snowpack density and temperature profiles, rain profile, and free water content. These data were compared with calculated results based on microscopic scattering models for dry, surface melting, and very wet snowpacks.

  20. The global geochemistry of bomb-produced tritium - General circulation model compared to available observations and traditional interpretations

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Broecker, Wallace S.; Jouzel, Jean; Suozzo, Robert J.; Russell, Gary L.; Rind, David

    1989-01-01

    Observational evidence suggests that of the tritium produced during nuclear bomb tests that has already reached the ocean, more than twice as much arrived through vapor impact as through precipitation. In the present study, the Goddard Institute for Space Studies 8 x 10 deg atmospheric general circulation model is used to simulate tritium transport from the upper atmosphere to the ocean. The simulation indicates that tritium delivery to the ocean via vapor impact is about equal to that via precipitation. The model result is relatively insensitive to several imposed changes in tritium source location, in model parameterizations, and in model resolution. Possible reasons for the discrepancy are explored.

  1. Overlap statistics of shallow boundary layer clouds: comparing ground-based observations with large-eddy simulations

    NASA Astrophysics Data System (ADS)

    Orlandi, Emiliano; Corbetta, Gabriele; Heus, Thijs; Neggers, Roel; Crewell, Susanne

    2016-04-01

    As large-scale models for weather and climate have coarse spatial resolutions, they cannot resolve clouds within a vertical grid column and thus rely on parameterizations, leading to uncertainty in the representation of clouds and the way they overlap in the vertical. The uncertainty in the cloud overlap parameterizations remains a significant source of error in the Earth's radiation budget in general circulation models (GCMs). Most studies concerning cloud overlap mainly focused on either large ensemble of cloud types or deep convective cloud fields. Cumuliform boundary layer cloud fields have been less researched despite the fact that their irregularity in shape and in spatial distribution at subgrid scales can impact the cloud overlap significantly. In this study, high-resolution ground-based measurements are used to assess the realism of fine-scale numerical simulations of shallow cumulus cloud fields. The overlap statistics of cumuli as produced by i) local large-eddy simulations (LES) as well as ii) the big-domain ICON at cloud resolving resolutions are confronted with CloudNet datasets at the Jülich ObservatorY for Cloud Evolution (JOYCE). Cloud fraction masks are derived for five different cases during the April-August 2013 period, using gridded time-height datasets at various temporal and vertical resolutions. The overlap ratio (R), i.e. the ratio between cloud fraction by volume and by area, is studied as a function of the vertical resolution. Good agreement is found between R derived from observations and simulations. Simulated and observed decorrelation lengths are smaller (< 300 m) than previously reported (> 1 km). A similar diurnal variation in the overlap efficiency is found in observations and simulations. The inefficient overlap we found at sub-grid vertical scales has the potential of significantly affecting the vertical transfer of radiation, yet few GCMs take such overlap at small, unresolved scales into account. A better understanding of the

  2. A Randomized Trial Comparing Part-time Patching with Observation for Intermittent Exotropia in Children 12 to 35 Months Old

    PubMed Central

    Mohney, Brian G.; Cotter, Susan A.; Chandler, Danielle L.; Holmes, Jonathan M.; Chen, Angela M.; Melia, Michele; Donahue, Sean P.; Wallace, David K.; Kraker, Raymond T.; Christian, Melanie L.; Suh, Donny W.

    2015-01-01

    Objective To determine the effectiveness of part-time patching for treating intermittent exotropia (IXT) in young children Design Multicenter, randomized clinical trial Participants Two hundred one children 12 to 35-months-old with untreated IXT meeting the following criteria: 1) IXT at distance OR constant exotropia at distance and either IXT or exophoria at near; 2) ≥15 prism diopter (Δ) exodeviation at distance or near by prism and alternate cover test (PACT) but at least 10Δ exodeviation at distance by PACT. Methods Participants were randomly assigned to either observation (no treatment for 6 months) or patching prescribed for 3 hours daily for 5 months, followed by 1 month of no patching. Main Outcome Measure The primary outcome was deterioration, defined as constant exotropia measuring at least 10Δ at distance and near or receipt of non-protocol treatment for IXT. Results Of the 177 participants (88%) completing the 6-month primary outcome examination, deterioration occurred in 4.6% (4 of 87) of the participants in the observation group and in 2.2% (2 of 90) of the participants in the patching group (difference = 2.4%; P = 0.27, 95% confidence interval (CI) = -3.8% to +9.4%). Motor deterioration occurred in 2.3% (2 of 87) of the observation group and in 2.2% (2 of 90) of the patching group (difference = 0.08%, P = 0.55, 95% CI = -5.8% to +6.1%). For the observation and patching groups respectively, 6-month mean PACT measurements were 27.9Δ versus 24.9Δ at distance (P = 0.02) and 19.3Δ versus 17.0Δ at near (P = 0.10); 6-month mean exotropia control scores were 2.8 vs. 2.3 points at distance (P = 0.02), and 1.4 vs. 1.1 points at near (P = 0.26). Conclusion Among children 12 to 35 months of age with previously untreated IXT, deterioration over 6 months was uncommon, with or without patching treatment. There was insufficient evidence to recommend part-time patching for the treatment of IXT in children in this age group. PMID:26072346

  3. Basal Temperature Measurement Using a Multi-Sensor Armband in Australian Young Women: A Comparative Observational Study

    PubMed Central

    Henningham, Lucy; Gorelik, Alexandra; Jayasinghe, Yasmin; Hartley, Stefanie; Garland, Suzanne Marie

    2015-01-01

    Background The menstrual cycle is a key marker of health in women of reproductive age. Monitoring ovulation is useful in health studies involving young women. The upward shift in basal body temperature, which occurs shortly after ovulation and continues until the next menses, is a potentially useful marker of ovulation, which has been exploited in clinical and research settings. Objective We investigated the utility of BodyMedia SenseWear (BMSW) in monitoring ovulation in young women by analyzing the correlation and agreement of basal temperatures measured using BMSW and a digital oral thermometer. Methods Kappa statistics were used to determine the agreement in ovulation detection between the two devices, for each participant, under each form of analysis. Participants also completed an online questionnaire assessing the acceptability of both devices. Results We recruited 16 participants with 15 of them providing analyzable data (11 OCP non-users, 4 OCP users). Weak to moderate correlations were observed between thermometer and BMSW temperature measurements averaged over 5 different time intervals. However, no agreement between methods was observed using Bland-Altman plots. There was a significant difference in the range of temperatures that each device recorded (thermometer: 35.3-37.2°C, BMSW: 29.7-36.7°C) with BMSW temperatures significantly lower than thermometer temperatures: mean 34.6°C (SD 1.2) versus 36.4°C (SD 0.3) respectively, P<.001. Poor agreement was observed between devices under quantitative analysis of ovulation while fair agreement was observed under visual analysis. Under both quantitative and visual analysis, there was 0% agreement for evidence of ovulation. Conclusions This study demonstrated the importance of evaluating biomeasures collected using mobile monitoring devices by comparison with standard methods. It revealed a relatively poor correlation between BMSW and oral thermometer temperature readings and suggested that BMSW is unlikely

  4. Atmospheric water parameters in mid-latitude cyclones observed by microwave radiometry and compared to model calculations

    NASA Technical Reports Server (NTRS)

    Katsaros, Kristina B.; Hammarstrand, Ulla; Petty, Grant W.

    1990-01-01

    Existing and experimental algorithms for various parameters of atmospheric water content such as integrated water vapor, cloud water, precipitation, are used to examine the distribution of these quantities in mid latitude cyclones. The data was obtained from signals given by the special sensor microwave/imager (SSM/I) and compared with data from the nimbus scanning multichannel microwave radiometer (SMMR) for North Atlantic cyclones. The potential of microwave remote sensing for enhancing knowledge of the horizontal structure of these storms and to aid the development and testing of the cloud and precipitation aspects of limited area numerical models of cyclonic storms is investigated.

  5. Chandra and RXTE Observations of 1E 1547.0-5408: Comparing the 2008 and 2009 Outbursts

    NASA Technical Reports Server (NTRS)

    Ng, C.-Y.; Kaspi, V. M.; Dib, R.; Olausen, S. A.; Scholz, P.; Guever, T.; Oezel, F.; Gavril, F. P.; Woods, P. M.

    2010-01-01

    We present results from observations of the magnetar 1E 1547.0-5408 (SGR J1550-5418) taken with the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer (RXTE) following the source s outbursts in 2008 October and 2009 January. During the time span of the Chandra observations, which covers days 4 through 23 and days 2 through 16 after the 2008 and 2009 events, respectively, the source spectral shape over the Chandraband remained stable, while the pulsar s spindown rate in the same span in 2008 increased by a factor of 2.2 as measured by RXTE. This suggests decoupling between the source s spin-down and radiative changes, hence between the spin-down-inferred magnetic field strength and that inferred spectrally. The lack of spectral variation during flux decay is surprising for models of magnetar outbursts. We also found a strong anti-correlation between the phase-averaged flux and the pulsed fraction in the 2008 and 2009 Chandra data, but not in the pre-2008 measurements. We discuss these results in the context of the magnetar model.

  6. ARTEMIS observations of lunar wake structure compared with hybrid ­kinetic simulations and an analytic model

    NASA Astrophysics Data System (ADS)

    Gharaee, H.; Rankin, R.; Marchand, R.; Paral, J.

    2014-12-01

    The ARTEMIS mission has made extensive measurements on the density and magnetic field structure of the lunar wake under different solar wind and magnetosphere conditions. Hybrid-kinetic simulations of the lunar wake have been found to be generally in good agreement with observations [Wiehle, S., et al., Planet. Space Sci., 2011], but are not readily available as they require access to large computers and human resources with expertise using this technology. It would be very useful to have an analytic model of the lunar wake, and one such model will be presented. It is based on an approach outlined by Hutchinson [Hutchinson, I., Physics Of Plasmas, 2008], and makes assumptions of cylindrical geometry, a strong and constant magnetic field, and fixed transverse velocity and temperature. Under these approximations the ion fluid equations (with massless electrons assumed) can be solved analytically by the method of characteristics. This paper demonstrates that the analytic model under these assumptions provides excellent agreement with observations and hybrid-kinetic simulations of the lunar wake. The approach outlined by Hutchinson is generalized to include an arbitrary angle between the interplanetary magnetic field and solar wind flow. This results in two angle-dependent characteristics for the fluid flow that can be solved for the density inside the wake region. The Density profiles for different orientations of magnetic field with respect to solar wind flow are in a good qualitative agreement with 2D Hybrid simulation results of the model developed by [Paral and Rankin, Nature Comms, 2012], and with ARTEMIS observations. Refrences, -Wiehle, S., et al. (2011), First Lunar wake passage of Artemis: Discrimination of wake effects and solar wind flactuations by 3D hybrid simulations, Planet. Space Sci., 59, 661-671, doi:10.1016/j.pss.2011.01.012. -Hutchinson, I. (2008),Oblique ion collection in the drift approximation:How magnetized Mach probes really work, Physics Of

  7. Scaling relations between black holes and their host galaxies: comparing theoretical and observational measurements, and the impact of selection effects

    NASA Astrophysics Data System (ADS)

    DeGraf, C.; Di Matteo, T.; Treu, T.; Feng, Y.; Woo, J.-H.; Park, D.

    2015-11-01

    We use the high-resolution simulation MassiveBlackII to examine scaling relations between black hole (BH) mass and host galaxy properties (σ, total M* and LV), finding good agreement with recent observational data, especially at the high-mass end. We find Gaussian intrinsic scatter (˜half the observed scatter) about all three relations, except among the most massive objects. Below z ˜ 2 the slope of the relations remain roughly z-independent, and only steepen by 50 per cent by z ˜ 4. The normalization of the σ, LV relations evolve by 0.3, 0.43 dex, while the M* correlation does not evolve out to at least z ˜ 2. Testing for selection biases, we find MBH- or M*-selected samples have steeper slopes than random samples, suggesting a constant-mass selection function can exhibit faster evolution than a random sample. We find a potential bias among high-LBH subsamples due to their more massive hosts, but that bright (active) active galactic nuclei exhibit no intrinsic bias relative to fainter (inactive) BHs in equivalent-mass hosts. Finally, we show that BHs below the local relation tend to grow faster than their host (72 per cent of BHs >0.3 dex below the mean relation have an MBH-M* trajectory steeper than the local relation), while those above have shallower trajectories (only 14 per cent are steeper than local). Thus BHs tend to grow faster than their hosts until surpassing the local relation, when their growth is suppressed, bringing them back towards the mean relation.

  8. Drivers' phone use at red traffic lights: a roadside observation study comparing calls and visual-manual interactions.

    PubMed

    Huth, Véronique; Sanchez, Yann; Brusque, Corinne

    2015-01-01

    Phone use while driving has become one of the priority issues in road safety, given that it may lead to decreased situation awareness and deteriorated driving performance. It has been suggested that drivers can regulate their exposure to secondary tasks and seek for compatibility of phone use and driving. Phone use strategies include the choice of driving situations with low demands and interruptions of the interaction when the context changes. Traffic light situations at urban intersections imply both a temptation to use the phone while waiting at the red traffic light and a potential threat due to the incompatibility of phone use and driving when the traffic light turns green. These two situations were targeted in a roadside observation study, with the aim to investigate the existence of a phone use strategy at the red traffic light and to test its effectiveness. N=124 phone users and a corresponding control group of non-users were observed. Strategic phone use behaviour was detected for visual-manual interactions, which are more likely to be initiated at the red traffic light and tend to be stopped before the vehicle moves off, while calls are less likely to be limited to the red traffic light situation. As an indicator of impaired situation awareness, delayed start was associated to phone use and in particular to visual-manual interactions, whether phone use was interrupted before moving off or not. Traffic light situations do not seem to allow effective application of phone use strategies, although drivers attempt to do so for the most demanding phone use mode. The underlying factors of phone use need to be studied so as to reduce the temptation of phone use and facilitate exposure regulation strategies.

  9. High-latitude E Region Ionosphere-thermosphere Coupling: A Comparative Study Using in Situ and Incoherent Scatter Radar Observations

    NASA Technical Reports Server (NTRS)

    Burchill, J. K.; Clemmons, J. H.; Knudsen, D. J.; Larsen, M.; Nicolls, M. J.; Pfaff, R. F.; Rowland, D.; Sangalli, L.

    2012-01-01

    We present in situ and ground-based measurements of the ratio k of ion cyclotronangular frequency to ion-neutral momentum transfer collision frequency to investigateionosphere-thermosphere (IT) coupling in the auroral E region. In situ observations were obtained by NASA sounding rocket 36.234, which was launched into the nightsideE region ionosphere at 1229 UT on 19 January 2007 from Poker Flat, AK. The payload carried instrumentation to determine ion drift angle and electric field vectors. Neutral winds were measured by triangulating a chemical tracer released from rocket 41.064 launched two minutes later. k is calculated from the rotation of the ion drift angle relative to the E-cross-B drift direction in a frame co-rotating with the payload. Between the altitudes of 118 km and 130 km k increases exponentially with a scale height of 9.3 +/- 0.7 km, deviating from an exponential above 130 km. k = 1 at an altitude z(sub0) of 119.9 +/- 0.5 km. The ratio was also estimated from Poker Flat Incoherent Scatter Radar (PFISR) measurements using the rotation of ion velocity with altitude. Exponential fits to the PFISR measurements made during the flight of 41.064 yield z(sub0) 115.9 +/- 1.2 km and a scale height of 9.1 +/- 1.0 km. Differences between in situ and ground-based measurements show that the E region atmospheric densities were structured vertically and/or horizontally on scales of 1 km to 10 km. There were no signs of ionospheric structure in ion density or ion temperature below scales of 1 km. The observations demonstrate the accuracy with which the in situ and PFISR data may be used as probes of IT coupling.

  10. Young Adult Utilization of a Smoking Cessation Website: An Observational Study Comparing Young and Older Adult Patterns of Use

    PubMed Central

    Ilakkuvan, Vinu; Graham, Amanda L; Richardson, Amanda; Xiao, Haijun; Mermelstein, Robin J; Curry, Susan J; Sporer, Amy K; Vallone, Donna M

    2016-01-01

    Background There is little research on how young adults or young adult subgroups utilize and engage with Web-based cessation interventions when trying to quit smoking. Addressing this knowledge gap is important to identify opportunities to optimize the effectiveness of online cessation programs across diverse young adult users. Objective This study examines utilization of the BecomeAnEX.org smoking cessation website among young adults and young adult subgroups compared with older adults to identify patterns of use by age, gender, and race/ethnicity. Methods Study participants were 5983 new registered users on a free smoking cessation website who were aged 18 to 70 years. Website utilization was tracked for 6 months; metrics of use included website visits, pages per visit, length of visit, and interaction with specific website features. Differences in website use by age were examined via bivariate analyses and multivariate logistic regression adjusted for age, gender, and race/ethnicity. Interactions were examined to determine differences by gender and race/ethnicity within young (18- to 24-year-olds and 25- to 34-year-olds) and older (35 years and older) adult segments. Results A greater percentage of young adults aged 18 to 34 years visited the site only once compared with older adults aged 35 years and older (72.05% vs 56.59%, respectively; P<.001). Young adults also spent less time on the site and viewed fewer pages than older adults. In adjusted analyses, young adults were significantly less likely than older adults to visit the site more than once (18-24 years: adjusted odds ratio [AOR] 0.58, 95% CI 0.49-0.68, P<.001; 25-34 years: AOR 0.56, 95% CI 0.50-0.64, P<.001), spend more than 3 minutes on the site (18-24 years: AOR 0.67, 95% CI 0.57-0.79, P<.001; 25-34 years: AOR 0.56, 95% CI 0.49-0.64, P<.001), view 12 or more pages (18-24 years: AOR 0.72, 95% CI 0.61-0.83; P<.001; 25-34 years: AOR 0.67, 95% CI 0.59-0.76, P<.001), utilize the BecomeAnEX.org community

  11. A Randomized Trial Comparing Part-time Patching with Observation for Children 3–10 Years Old with Intermittent Exotropia

    PubMed Central

    Cotter, Susan A.; Mohney, Brian G.; Chandler, Danielle L.; Holmes, Jonathan M.; Repka, Michael X.; Melia, Michele; Wallace, David K.; Beck, Roy W.; Birch, Eileen E.; Kraker, Raymond T.; Tamkins, Susanna M.; Miller, Aaron M.; Sala, Nicholas A.; Glaser, Stephen R.

    2014-01-01

    Objective To determine the effectiveness of prescribed part-time patching for treatment of intermittent exotropia in children Design Multicenter, randomized clinical trial Participants Three hundred fifty-eight children aged 3 to < 11 years old with previously untreated (except for refractive correction) intermittent exotropia (IXT) and near stereoacuity of 400 arcsec or better were enrolled. Intermittent exotropia met the following criteria: 1) constant or intermittent exotropia at distance and either intermittent exotropia or exophoria at near; 2) exodeviation (tropia or phoria) of at least 15 prism diopters (Δ) at distance or near by prism and alternate cover test (PACT); and 3) exodeviation of at least 10Δ at distance by PACT. Methods Participants were randomly assigned to either observation (no treatment for 6 months) or patching for 3 hours per day for 5 months, with a 1-month washout period of no patching before the 6-month primary outcome exam. Main Outcome Measure The primary outcome was deterioration at either the 3-month or the 6-month follow-up visit, defined as: 1) constant exotropia measuring at least 10Δ at distance and near by simultaneous prism and cover test, and/or 2) near stereoacuity decreased by at least 2 octaves from baseline, both assessed by a masked examiner and confirmed by a retest. Participants who were prescribed any non-randomized treatment without first meeting either deterioration criteria were also counted as having deteriorated. Results Of the 324 (91%) participants completing the 6-month primary outcome exam, deterioration occurred in 10 (6.1%) of the 165 participants in the observation group (3 of these 10 started treatment without meeting deterioration criteria) and in 1 (0.6%) of the 159 participants in the part-time patching group (difference = 5.4%, lower limit of one-sided exact 95% confidence interval = 2.0%; p value from one-sided hypothesis test = 0.004). Conclusion Deterioration of previously untreated childhood IXT

  12. Symptom Burden and Quality of Life in Patients with Follicular Lymphoma undergoing Maintenance Treatment with Rituximab Compared with Observation

    PubMed Central

    Walker, Mark S.; Stepanski, Edward J.; Reyes, Carolina; Satram-Hoang, Sacha; Houts, Arthur C.; Schwartzberg, Lee S.

    2011-01-01

    Background: The impact on health related quality of life (HRQoL) of rituximab maintenance (R-M) versus observation (OBS) after induction for treatment of follicular lymphoma (FL) is unclear. Methods: We reviewed the charts of 137 patients (53% female, 87% White, age 61.0 ± 12.4 years) who received either R-M (n = 53) or OBS (n = 84) after chemotherapy induction for newly diagnosed FL at community oncology practices within the US. Patients (65% with advanced disease; 48% with a high FLIPI score [3–5]) had completed ≥1 Patient Care Monitor HRQoL survey in the period following front-line therapy, and were excluded if they had progressed during front-line therapy. Results: Linear mixed models showed that postinduction, most symptoms were stable, with patients on R-M reporting HRQoL that was equal to that reported by OBS patients. Conclusions: Among R-M patients, receipt of rituximab was associated with improved psychological symptoms. PMID:23556084

  13. Comparing the ρ and χ class spectra of the microquasar GRS 1915+105 observed with BeppoSAX

    NASA Astrophysics Data System (ADS)

    Mineo, T.; Del Santo, M.; Massaro, E.; Massa, F.; D'Aì, A.

    2017-02-01

    Context. BeppoSAX observed GRS 1915+105 during two variability classes at the same 2-10 keV flux level. The ρ class is characterized by quasi-periodic flares recurring on a time-scale of 1 to 2 min, namely heartbeat, while the χ class is characterized by no strong temporal variability. Aims: The aim of this work is to coherently analyze the source spectrum in these two classes and to gain insight into the source conditions that inset the heartbeats. Methods: A single χ spectrum was accumulated, while ρ data were split in runs where five phase-resolved spectra were selected. In addition to the multicolor disc black body, the fitting model includes a hybrid Comptonization plus a Compton reflection component. Results: Our results show that the emission in the ρ class is dominated by the multi-temperature disk, while in the χ class the Comptonised component is dominant. The disk temperature varies between a maximum of 1.95 ± 0.11 keV reached at the peak and a minimum of 0.95 keV in the χ class. In both classes we detect a significant contribution from a non-thermal electron population to the total Comptonized emission. A broadened iron emission line is detected in the χ spectrum. We interpret the line shape as being due to reflection from an accretion disk extremely close to the black-hole ( gravitational radii), with an equivalent width of 200 ± 20 eV. Concomitantly, upper limits of 150 eV can be derived from the ρ spectra. Conclusions: In the framework of coupled disc-corona models, these results point out that the source emission is strongly affected by the fractions of accretion energy distributed between the disk, the corona, and possibly the wind, with no indication on the conditions that inset the heartbeats.

  14. Comparing the Invasibility of Experimental “Reefs” with Field Observations of Natural Reefs and Artificial Structures

    PubMed Central

    Dafforn, Katherine A.; Glasby, Tim M.; Johnston, Emma L.

    2012-01-01

    Natural systems are increasingly being modified by the addition of artificial habitats which may facilitate invasion. Where invaders are able to disperse from artificial habitats, their impact may spread to surrounding natural communities and therefore it is important to investigate potential factors that reduce or enhance invasibility. We surveyed the distribution of non-indigenous and native invertebrates and algae between artificial habitats and natural reefs in a marine subtidal system. We also deployed sandstone plates as experimental ‘reefs’ and manipulated the orientation, starting assemblage and degree of shading. Invertebrates (non-indigenous and native) appeared to be responding to similar environmental factors (e.g. orientation) and occupied most space on artificial structures and to a lesser extent reef walls. Non-indigenous invertebrates are less successful than native invertebrates on horizontal reefs despite functional similarities. Manipulative experiments revealed that even when non-indigenous invertebrates invade vertical “reefs”, they are unlikely to gain a foothold and never exceed covers of native invertebrates (regardless of space availability). Community ecology suggests that invertebrates will dominate reef walls and algae horizontal reefs due to functional differences, however our surveys revealed that native algae dominate both vertical and horizontal reefs in shallow estuarine systems. Few non-indigenous algae were sampled in the study, however where invasive algal species are present in a system, they may present a threat to reef communities. Our findings suggest that non-indigenous species are less successful at occupying space on reef compared to artificial structures, and manipulations of biotic and abiotic conditions (primarily orientation and to a lesser extent biotic resistance) on experimental “reefs” explained a large portion of this variation, however they could not fully explain the magnitude of differences. PMID

  15. Comparing Physically Abusive, Neglectful, and Non-Maltreating Parents during Interactions with Their Children: A Meta-Analysis of Observational Studies

    ERIC Educational Resources Information Center

    Wilson, Steven R.; Rack, Jessica J.; Shi, Xiaowei; Norris, Alda M.

    2008-01-01

    Objective: To clarify the nature and extent of differences in the ways that physically abusive, neglectful, and non-maltreating parents communicate during interactions with their children. Method: A meta-analysis was conducted of 33 observational studies comparing parent-child interactions in families where parents have a documented history of…

  16. Reducing radiation dose to selected organs by selecting the tube start angle in MDCT helical scans: A Monte Carlo based study

    SciTech Connect

    Zhang Di; Zankl, Maria; DeMarco, John J.; Cagnon, Chris H.; Angel, Erin; Turner, Adam C.; McNitt-Gray, Michael F.

    2009-12-15

    Purpose: Previous work has demonstrated that there are significant dose variations with a sinusoidal pattern on the peripheral of a CTDI 32 cm phantom or on the surface of an anthropomorphic phantom when helical CT scanning is performed, resulting in the creation of ''hot'' spots or ''cold'' spots. The purpose of this work was to perform preliminary investigations into the feasibility of exploiting these variations to reduce dose to selected radiosensitive organs solely by varying the tube start angle in CT scans. Methods: Radiation dose to several radiosensitive organs (including breasts, thyroid, uterus, gonads, and eye lenses) resulting from MDCT scans were estimated using Monte Carlo simulation methods on voxelized patient models, including GSF's Baby, Child, and Irene. Dose to fetus was also estimated using four pregnant female models based on CT images of the pregnant patients. Whole-body scans were simulated using 120 kVp, 300 mAs, both 28.8 and 40 mm nominal collimations, and pitch values of 1.5, 1.0, and 0.75 under a wide range of start angles (0 deg. - 340 deg. in 20 deg. increments). The relationship between tube start angle and organ dose was examined for each organ, and the potential dose reduction was calculated. Results: Some organs exhibit a strong dose variation, depending on the tube start angle. For small peripheral organs (e.g., the eye lenses of the Baby phantom at pitch 1.5 with 40 mm collimation), the minimum dose can be 41% lower than the maximum dose, depending on the tube start angle. In general, larger dose reductions occur for smaller peripheral organs in smaller patients when wider collimation is used. Pitch 1.5 and pitch 0.75 have different mechanisms of dose reduction. For pitch 1.5 scans, the dose is usually lowest when the tube start angle is such that the x-ray tube is posterior to the patient when it passes the longitudinal location of the organ. For pitch 0.75 scans, the dose is lowest when the tube start angle is such that the x

  17. Applications of propensity score methods in observational comparative effectiveness and safety research: where have we come and where should we go?

    PubMed

    Borah, Bijan J; Moriarty, James P; Crown, William H; Doshi, Jalpa A

    2014-01-01

    Propensity score (PS) methods have proliferated in recent years in observational studies in general and in observational comparative effectiveness research (CER) in particular. PS methods are an important set of tools for estimating treatment effects in observational studies, enabling adjustment for measured confounders in an easy-to-understand and transparent way. This article demonstrates how PS methods have been used to address specific CER questions from 2001 through to 2012 by identifying six impactful studies from this period. This article also discusses areas for improvement, including data infrastructure, and a unified set of guidelines in terms of PS implementation and reporting, which will boost confidence in evidence generated through observational CER using PS methods.

  18. A prospective, observational study comparing the PK/PD relationships of generic Meropenem (Mercide®) to the innovator brand in critically ill patients

    PubMed Central

    Mer, Mervyn; Snyman, Jacques Rene; van Rensburg, Constance Elizabeth Jansen; van Tonder, Jacob John; Laurens, Ilze

    2016-01-01

    Introduction Clinicians’ skepticism, fueled by evidence of inferiority of some multisource generic antimicrobial products, results in the underutilization of more cost-effective generics, especially in critically ill patients. The aim of this observational study was to demonstrate equivalence between the generic or comparator brand of meropenem (Mercide®) and the leading innovator brand (Meronem®) by means of an ex vivo technique whereby antimicrobial activity is used to estimate plasma concentration of the active moiety. Methods Patients from different high care and intensive care units were recruited for observation when prescribed either of the meropenem brands under investigation. Blood samples were collected over 6 hours after a 30 minute infusion of the different brands. Meropenem concentration curves were established against United States Pharmacopeia standard meropenem (Sigma-Aldrich) by using standard laboratory techniques for culture of Klebsiella pneumoniae. Patients’ plasma samples were tested ex vivo, using a disc diffusion assay, to confirm antimicrobial activity and estimate plasma concentrations of the two brands. Results Both brands of meropenem demonstrated similar curves in donor plasma when concentrations in vials were confirmed. Patient-specific serum concentrations were determined from zones of inhibition against a standard laboratory Klebsiella strain ex vivo, confirming at least similar in vivo concentrations as the concentration curves (90% confidence interval) overlapped; however, the upper limit of the area under the curve for the ratio comparator/innovator exceeded the 1.25-point estimate, i.e., 4% higher for comparator meropenem. Conclusion This observational, in-practice study demonstrates similar ex vivo activity and in vivo plasma concentration time curves for the products under observation. Assay sensitivity is also confirmed. Current registration status of generic small molecules is in place. The products are therefore

  19. Bone Mineral Density Estimations From Routine Multidetector Computed Tomography: A Comparative Study of Contrast and Calibration Effects

    PubMed Central

    Kaesmacher, Johannes; Liebl, Hans; Baum, Thomas; Kirschke, Jan Stefan

    2017-01-01

    Introduction Phantom-based (synchronous and asynchronous) and phantomless (internal tissue calibration based) assessment of bone mineral density (BMD) in routine MDCT (multidetector computed tomography) examinations potentially allows for diagnosis of osteoporosis. Although recent studies investigated the effects of contrast-medium application on phantom-calibrated BMD measurements, it remains uncertain to what extent internal tissue-calibrated BMD measurements are also susceptible to contrast-medium associated density variation. The present study is the first to systemically evaluate BMD variations related to contrast application comparing different calibration techniques. Purpose To compare predicative performance of different calibration techniques for BMD measurements obtained from triphasic contrast-enhanced MDCT. Materials and Methods Bone mineral density was measured on nonenhanced (NE), arterial (AR) and portal-venous (PV) contrast phase MDCT images of 46 patients using synchronous (SYNC) and asynchronous (ASYNC) phantom calibration as well as internal calibration (IC). Quantitative computed tomography (QCT) served as criterion standard. Density variations were analyzed for each contrast phase and calibration technique, and respective linear fitting was performed. Results Both asynchronous calibration-derived BMD values (NE-ASYNC) and values estimated using IC (NE-IC) on NE MDCT images did reasonably well in predicting QCT BMD (root-mean-square deviation, 8.0% and 7.8%, respectively). Average NE-IC BMD was 2.7% lower when compared with QCT (P = 0.017), whereas no difference could be found for NE-ASYNC (P = 0.957). All average BMD estimates derived from contrast-enhanced scans differed significantly from QCT BMD (all P < 0.005) and led to notable systemic BMD biases (mean difference at least > 6.0 mg/mL). All regression fits revealed a consistent linear dependency (R2 range, 0.861–0.963). Overall accuracy and goodness of fit tended to decrease from AR to

  20. Large-scale numerical simulations of star formation put to the test. Comparing synthetic images and actual observations for statistical samples of protostars

    NASA Astrophysics Data System (ADS)

    Frimann, S.; Jørgensen, J. K.; Haugbølle, T.

    2016-02-01

    Context. Both observations and simulations of embedded protostars have progressed rapidly in recent years. Bringing them together is an important step in advancing our knowledge about the earliest phases of star formation. Aims: To compare synthetic continuum images and spectral energy distributions (SEDs), calculated from large-scale numerical simulations, to observational studies, thereby aiding in both the interpretation of the observations and in testing the fidelity of the simulations. Methods: The adaptive mesh refinement code, RAMSES, is used to simulate the evolution of a 5 pc × 5 pc × 5 pc molecular cloud. The simulation has a maximum resolution of 8 AU, resolving simultaneously the molecular cloud on parsec scales and individual protostellar systems on AU scales. The simulation is post-processed with the radiative transfer code RADMC-3D, which is used to create synthetic continuum images and SEDs of the protostellar systems. In this way, more than 13 000 unique radiative transfer models, of a variety of different protostellar systems, are produced. Results: Over the course of 0.76 Myr the simulation forms more than 500 protostars, primarily within two sub-clusters. The synthetic SEDs are used to calculate evolutionary tracers Tbol and Lsmm/Lbol. It is shown that, while the observed distributions of the tracers are well matched by the simulation, they generally do a poor job of tracking the protostellar ages. Disks form early in the simulation, with 40% of the Class 0 protostars being encircled by one. The flux emission from the simulated disks is found to be, on average, a factor ~6 too low relative to real observations; an issue that can be traced back to numerical effects on the smallest scales in the simulation. The simulated distribution of protostellar luminosities spans more than three order of magnitudes, similar to the observed distribution. Cores and protostars are found to be closely associated with one another, with the distance distribution

  1. Comparative Evaluation of Retrocrural versus Transaortic Neurolytic Celiac Plexus Block for Pain Relief in Patients with Upper Abdominal Malignancy: A Retrospective Observational Study

    PubMed Central

    Tewari, Saipriya; Agarwal, Anil; Dhiraaj, Sanjay; Gautam, Sujeet K; Khuba, Sandeep; Madabushi, Rajashree; Shamshery, Chetna; Kumar, Sanjay

    2016-01-01

    Aim: To compare retrocrural versus transaortic techniques for neurolytic celiac plexus block (NCPB) in patients suffering from upper abdominal malignancy. Methods: In this retrospective observational study between October 2013 and April 2015, 64 patients with inoperable upper abdominal malignancy received fluoroscopy-guided percutaneous NCPB in our institute. Their case files were reviewed and the patients were divided into two groups depending on the technique used to perform NCPB: retrocrural (Group R; n = 36) versus transaortic (Group T; n = 28). The primary outcome measure was pain as assessed with a numeric rating scale (NRS) from 0 to 10; the secondary outcome measures were morphine consumption per day (M), quality of life (QOL) as assessed by comparing the percent of positive responses in each group, and complications if any. These were noted and analyzed prior to intervention and then on day 1, weeks 1, 2, 3, and months 1, 2, 3, 6 following NCPB. Results: Patients in Group R had significantly reduced NRS pain scores at week 1, 2, 3, month 1 and 2 as compared to Group T (P < 0.05). Morphine consumption also reduced significantly in Group R at day 1, week 1, 2, and 3 (P < 0.05). QOL was found to be comparable between the groups, and no major complications were noted. Conclusion: Retrocrural NCPB provides superior pain relief along with a reduction in morphine consumption as compared to transaortic NCPB in patients with pain due to upper abdominal malignancy. PMID:27559259

  2. A Randomized Trial Comparing the Efficacy and Safety of Intravitreal Triamcinolone With Observation to Treat Vision Loss Associated With Macular Edema Secondary to Central Retinal Vein Occlusion

    PubMed Central

    Ip, Michael S.; Scott, Ingrid U.; VanVeldhuisen, Paul C.; Oden, Neal L.; Blodi, Barbara A.; Fisher, Marian; Singerman, Lawrence J.; Tolentino, Michael; Chan, Clement K.; Gonzalez, Victor H.

    2009-01-01

    Objective: To compare the efficacy and safety of 1-mg and 4-mg doses of preservative-free intravitreal triamcinolone with observation for eyes with vision loss associated with macular edema secondary to perfused central retinal vein occlusion (CRVO). Methods: Multicenter, randomized, clinical trial of 271 participants. Main Outcome Measure: Gain in visual acuity letter score of 15 or more from baseline to month 12. Results: Seven percent, 27%, and 26% of participants achieved the primary outcome in the observation, 1-mg, and 4-mg groups, respectively. The odds of achieving the primary outcome were 5.0 times greater in the 1-mg group than the observation group (odds ratio [OR],5.0; 95% confidence interval [CI], 1.8-14.1; P=.001) and 5.0 times greater in 4-mg group than the observation group (OR,5.0; 95% CI, 1.8-14.4; P=.001); there was no difference identified between the 1-mg and 4-mg groups (OR, 1.0; 95% CI, 0.5-2.1; P=.97). The rates of elevated intraocular pressure and cataract were similar for the observation and 1-mg groups, but higher in the 4-mg group. Conclusions: Intravitreal triamcinolone is superior to observation for treating vision loss associated with macular edema secondary to CRVO in patients who have characteristics similar to those in the SCORE-CRVO trial. The 1-mg dose has a safety profile superior to that of the 4-mg dose. Application to Clinical Practice: Intravitreal triamcinolone in a 1-mg dose, following the retreatment criteria applied in the SCORE Study, should be considered for up to 1 year, and possibly 2 years, for patients with characteristics similar to those in the SCORE-CRVO trial. Trial Registration: clinicaltrials.gov Identifier: NCT00105027 PMID:19752419

  3. Observed and modelled effects of auroral precipitation on the thermal ionospheric plasma: comparing the MICA and Cascades2 sounding rocket events

    NASA Astrophysics Data System (ADS)

    Lynch, K. A.; Gayetsky, L.; Fernandes, P. A.; Zettergren, M. D.; Lessard, M.; Cohen, I. J.; Hampton, D. L.; Ahrns, J.; Hysell, D. L.; Powell, S.; Miceli, R. J.; Moen, J. I.; Bekkeng, T.

    2012-12-01

    Auroral precipitation can modify the ionospheric thermal plasma through a variety of processes. We examine and compare the events seen by two recent auroral sounding rockets carrying in situ thermal plasma instrumentation. The Cascades2 sounding rocket (March 2009, Poker Flat Research Range) traversed a pre-midnight poleward boundary intensification (PBI) event distinguished by a stationary Alfvenic curtain of field-aligned precipitation. The MICA sounding rocket (February 2012, Poker Flat Research Range) traveled through irregular precipitation following the passage of a strong westward-travelling surge. Previous modelling of the ionospheric effects of auroral precipitation used a one-dimensional model, TRANSCAR, which had a simplified treatment of electric fields and did not have the benefit of in situ thermal plasma data. This new study uses a new two-dimensional model which self-consistently calculates electric fields to explore both spatial and temporal effects, and compares to thermal plasma observations. A rigorous understanding of the ambient thermal plasma parameters and their effects on the local spacecraft sheath and charging, is required for quantitative interpretation of in situ thermal plasma observations. To complement this TRANSCAR analysis we therefore require a reliable means of interpreting in situ thermal plasma observation. This interpretation depends upon a rigorous plasma sheath model since the ambient ion energy is on the order of the spacecraft's sheath energy. A self-consistent PIC model is used to model the spacecraft sheath, and a test-particle approach then predicts the detector response for a given plasma environment. The model parameters are then modified until agreement is found with the in situ data. We find that for some situations, the thermal plasma parameters are strongly driven by the precipitation at the observation time. For other situations, the previous history of the precipitation at that position can have a stronger

  4. Validation of a previous day recall for measuring the location and purpose of active and sedentary behaviors compared to direct observation

    PubMed Central

    2014-01-01

    Purpose Gathering contextual information (i.e., location and purpose) about active and sedentary behaviors is an advantage of self-report tools such as previous day recalls (PDR). However, the validity of PDR’s for measuring context has not been empirically tested. The purpose of this paper was to compare PDR estimates of location and purpose to direct observation (DO). Methods Fifteen adult (18–75 y) and 15 adolescent (12–17 y) participants were directly observed during at least one segment of the day (i.e., morning, afternoon or evening). Participants completed their normal daily routine while trained observers recorded the location (i.e., home, community, work/school), purpose (e.g., leisure, transportation) and whether the behavior was sedentary or active. The day following the observation, participants completed an unannounced PDR. Estimates of time in each context were compared between PDR and DO. Intra-class correlations (ICC), percent agreement and Kappa statistics were calculated. Results For adults, percent agreement was 85% or greater for each location and ICC values ranged from 0.71 to 0.96. The PDR-reported purpose of adults’ behaviors were highly correlated with DO for household activities and work (ICCs of 0.84 and 0.88, respectively). Transportation was not significantly correlated with DO (ICC = -0.08). For adolescents, reported classification of activity location was 80.8% or greater. The ICCs for purpose of adolescents’ behaviors ranged from 0.46 to 0.78. Participants were most accurate in classifying the location and purpose of the behaviors in which they spent the most time. Conclusions This study suggests that adults and adolescents can accurately report where and why they spend time in behaviors using a PDR. This information on behavioral context is essential for translating the evidence for specific behavior-disease associations to health interventions and public policy. PMID:24490619

  5. Comparing methods for measuring peak look duration: are individual differences observed on screen-based tasks also found in more ecologically valid contexts?

    PubMed

    Wass, Sam V

    2014-08-01

    Convergent research points to the importance of studying the ontogenesis of sustained attention during the early years of life, but little research hitherto has compared and contrasted different techniques available for measuring sustained attention. Here, we compare methods that have been used to assess one parameter of sustained attention, namely infants' peak look duration to novel stimuli. Our focus was to assess whether individual differences in peak look duration are stable across different measurement techniques. In a single cohort of 42 typically developing 11-month-old infants we assessed peak look duration using six different measurement paradigms (four screen-based, two naturalistic). Zero-order correlations suggested that individual differences in peak look duration were stable across all four screen-based paradigms, but no correlations were found between peak look durations observed on the screen-based and the naturalistic paradigms. A factor analysis conducted on the dependent variable of peak look duration identified two factors. All four screen-based tasks loaded onto the first factor, but the two naturalistic tasks did not relate, and mapped onto a different factor. Our results question how individual differences observed on screen-based tasks manifest in more ecologically valid contexts.

  6. Comparing modelled predictions of neonatal mortality impacts using LiST with observed results of community-based intervention trials in South Asia

    PubMed Central

    Friberg, Ingrid K; Bhutta, Zulfiqar A; Darmstadt, Gary L; Bang, Abhay; Cousens, Simon; Baqui, Abdullah H; Kumar, Vishwajeet; Walker, Neff; Lawn, Joy E

    2010-01-01

    Background There is an increasing body of evidence from trials suggesting that major reductions in neonatal mortality are possible through community-based interventions. Since these trials involve packages of varying content, determining how much of the observed mortality reduction is due to specific interventions is problematic. The Lives Saved Tool (LiST) is designed to facilitate programmatic prioritization by modelling mortality reductions related to increasing coverage of specific interventions which may be combined into packages. Methods To assess the validity of LiST outputs, we compared predictions generated by LiST with observed neonatal mortality reductions in trials of packages which met inclusion criteria but were not used as evidence inputs for LiST. Results Four trials, all from South Asia, met the inclusion criteria. The neonatal mortality rate (NMR) predicted by LiST matched the observed rate very closely in two effectiveness-type trials. LiST predicted NMR reduction was close (absolute difference <5/1000 live births) in a third study. The NMR at the end of the fourth study (Shivgarh, India) was overestimated by 39% or 16/1000 live births. Conclusions These results suggest that LiST is a reasonably reliable tool for use by policymakers to prioritize interventions to reduce neonatal deaths, at least in South Asia and where empirical data are unavailable. Reasons for the underestimated reduction in one trial likely include the inability of LiST to model all effective interventions. PMID:20348113

  7. Validity and intra-observer reliability of three-dimensional scanning compared to conventional anthropometry for children and adolescents from a population-based cohort study.

    PubMed

    Glock, Fabian; Vogel, Mandy; Naumann, Stephanie; Kuehnapfel, Andreas; Scholz, Markus; Hiemisch, Andreas; Kirsten, Toralf; Rieger, Kristin; Koerner, Antje; Loeffler, Markus; Kiess, Wieland

    2017-01-04

    BackgroundConventional anthropometric measurements are time consuming and require well trained medical staff. To use three-dimensional whole body laser scanning in daily clinical work, validity and reliability have to be confirmed.MethodsWe compared a whole body laser scanner to conventional anthropometry in a group of 473 children and adolescents from the Leipzig Research Centre for Civilization Diseases (LIFE-Child). Concordance correlation coefficients (CCC) were calculated separately for sex, weight and age to assess validity. Overall CCC (OCCC) were used to analyze intra-observer reliability.ResultsBody height and the circumferences of waist, hip, upper arm and calf had an "excellent" (CCC ≥ 0.9), neck and thigh circumference a "good" (CCC ≥ 0.7) and head circumference a "low" (CCC < 0.5) degree of concordance over the complete study population. We observed dependencies of validity on sex, weight and age. Intra-observer reliability of both techniques is "excellent" (OCCC ≥ 0.9).ConclusionScanning is faster, requires a less intensive staff training and provides more information. It can be used in an epidemiologic setting with children and adolescents but some measurements should be considered with caution due to reduced agreement with conventional anthropometry.Pediatric Research (2017); doi:10.1038/pr.2016.274.

  8. Observer performance for adaptive, image-based denoising and filtered back projection compared to scanner-based iterative reconstruction for lower dose CT enterography

    PubMed Central

    Fletcher, Joel G.; Hara, Amy K.; Fidler, Jeff L.; Silva, Alvin C.; Barlow, John M.; Carter, Rickey E.; Bartley, Adam; Shiung, Maria; Holmes, David R.; Weber, Nicolas K.; Bruining, David H.; Yu, Lifeng; McCollough, Cynthia H.

    2015-01-01

    Purpose The purpose of this study was to compare observer performance for detection of intestinal inflammation for low-dose CT enterography (LD-CTE) using scanner-based iterative reconstruction (IR) vs. vendor-independent, adaptive image-based noise reduction (ANLM) or filtered back projection (FBP). Methods Sixty-two LD-CTE exams were performed. LD-CTE images were reconstructed using IR, ANLM, and FBP. Three readers, blinded to image type, marked intestinal inflammation directly on patient images using a specialized workstation over three sessions, interpreting one image type/patient/session. Reference standard was created by a gastroenterologist and radiologist, who reviewed all available data including dismissal Gastroenterology records, and who marked all inflamed bowel segments on the same workstation. Reader and reference localizations were then compared. Non-inferiority was tested using Jackknife free-response ROC (JAFROC) figures of merit (FOM) for ANLM and FBP compared to IR. Patient-level analyses for the presence or absence of inflammation were also conducted. Results There were 46 inflamed bowel segments in 24/62 patients (CTDIvol interquartile range 6.9–10.1 mGy). JAFROC FOM for ANLM and FBP were 0.84 (95% CI 0.75–0.92) and 0.84 (95% CI 0.75–0.92), and were statistically non-inferior to IR (FOM 0.84; 95% CI 0.76–0.93). Patient-level pooled confidence intervals for sensitivity widely overlapped, as did specificities. Image quality was rated as better with IR and AMLM compared to FBP (p < 0.0001), with no difference in reading times (p = 0.89). Conclusions Vendor-independent adaptive image-based noise reduction and FBP provided observer performance that was non-inferior to scanner-based IR methods. Adaptive image-based noise reduction maintained or improved upon image quality ratings compared to FBP when performing CTE at lower dose levels. PMID:25725794

  9. Stable time patterns of railway suicides in Germany: comparative analysis of 7,187 cases across two observation periods (1995–1998; 2005–2008)

    PubMed Central

    2014-01-01

    Background The majority of fatalities on the European Union (EU) railways are suicides, representing about 60% of all railway fatalities. The aim of this study was to compare time patterns of suicidal behaviour on railway tracks in Germany between two observation periods (1995–1998 and 2005–2008) in order to investigate their stability and value in railway suicide prevention. Methods Cases were derived from the National Central Registry of person accidents on the German railway network (STABAG). The association of daytime, weekday and month with the mean number of suicides was analysed applying linear regression. Potential differences by observation period were assessed by adding observation period and the respective interaction terms into the linear regression. A 95% confidence interval for the mean number of suicides was computed using the t distribution. Results A total of 7,187 railway suicides were recorded within both periods: 4,102 (57%) in the first period (1995–1998) and 3,085 (43%) in the second (2005–2008). The number of railway suicides was highest on Mondays and Tuesdays in the first period with an average of 3.2 and 3.5 events and of 2.6 events on both days in the second period. In both periods, railway suicides were more common between 6:00 am and noon, and between 6:00 pm and midnight. Seasonality was only prominent in the period 1995–1998. Conclusions Over the course of two observation periods, the weekday and circadian patterns of railway suicides remained stable. Therefore, these patterns should be an integral part of railway suicide preventive measures, e.g. gatekeeper training courses. PMID:24498876

  10. A comparative hospital-based observational study of mono- and co-infections of malaria, dengue virus and scrub typhus causing acute undifferentiated fever.

    PubMed

    Ahmad, S; Dhar, M; Mittal, G; Bhat, N K; Shirazi, N; Kalra, V; Sati, H C; Gupta, V

    2016-04-01

    Positive serology for dengue and/or scrub typhus infection with/without positive malarial smear (designated as mixed or co-infection) is being increasingly observed during epidemics of acute undifferentiated febrile illnesses (AUFIs). We planned to study the clinical and biochemical spectrum of co-infections with Plasmodium sp., dengue virus and scrub typhus and compare these with mono-infection by the same organisms. During the period from December 2012 to December 2013, all cases presenting with AUFIs to a single medical unit of a referral centre in Garhwal region of the north Indian state of Uttarakhand were retrospectively selected and categorised aetiologically as co-infections, malaria, dengue or scrub typhus. The groups thus created were compared in terms of demographic, clinical, biochemical and outcome parameters. The co-infection group (n = 49) was associated with milder clinical manifestations, fewer, milder and non-progressive organ dysfunction, and lesser need for intensive care, mechanical ventilation and dialysis as compared to mono-infections. When co-infections were sub-grouped and compared with the relevant mono-infections, there were differences in certain haematological and biochemical parameters; however, this difference did not translate into differential outcomes. Scrub typhus mono-infection was associated with severe disease in terms of both morbidity and mortality. Malaria, dengue and scrub typhus should be routinely tested in all patients with AUFIs. Co-infections, whether true or due to serological cross-reactivity, appear to be a separate entity so far as presentation and morbidity is concerned. Further insight is needed into the mechanism and identification of the protective infection.

  11. The clinical course of low back pain: a meta-analysis comparing outcomes in randomised clinical trials (RCTs) and observational studies

    PubMed Central

    2014-01-01

    Background Evidence suggests that the course of low back pain (LBP) symptoms in randomised clinical trials (RCTs) follows a pattern of large improvement regardless of the type of treatment. A similar pattern was independently observed in observational studies. However, there is an assumption that the clinical course of symptoms is particularly influenced in RCTs by mere participation in the trials. To test this assumption, the aim of our study was to compare the course of LBP in RCTs and observational studies. Methods Source of studies CENTRAL database for RCTs and MEDLINE, CINAHL, EMBASE and hand search of systematic reviews for cohort studies. Studies include individuals aged 18 or over, and concern non-specific LBP. Trials had to concern primary care treatments. Data were extracted on pain intensity. Meta-regression analysis was used to compare the pooled within-group change in pain in RCTs with that in cohort studies calculated as the standardised mean change (SMC). Results 70 RCTs and 19 cohort studies were included, out of 1134 and 653 identified respectively. LBP symptoms followed a similar course in RCTs and cohort studies: a rapid improvement in the first 6 weeks followed by a smaller further improvement until 52 weeks. There was no statistically significant difference in pooled SMC between RCTs and cohort studies at any time point:- 6 weeks: RCTs: SMC 1.0 (95% CI 0.9 to 1.0) and cohorts 1.2 (0.7to 1.7); 13 weeks: RCTs 1.2 (1.1 to 1.3) and cohorts 1.0 (0.8 to 1.3); 27 weeks: RCTs 1.1 (1.0 to 1.2) and cohorts 1.2 (0.8 to 1.7); 52 weeks: RCTs 0.9 (0.8 to 1.0) and cohorts 1.1 (0.8 to 1.6). Conclusions The clinical course of LBP symptoms followed a pattern that was similar in RCTs and cohort observational studies. In addition to a shared ‘natural history’, enrolment of LBP patients in clinical studies is likely to provoke responses that reflect the nonspecific effects of seeking and receiving care, independent of the study design. PMID:24607083

  12. Classification of Particle Shapes from Lidar Depolarization Ratios in Convective Ice Clouds Compared to in situ Observations During CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    Noel, Vincent; Winker, David; McGill, Matthew; Lawson, Paul

    2004-01-01

    This manuscript describes a method to class@ cirrus cloud ice particle shape using lidar depolarization measurements as a basis for segregating different particle shape regimes. Measurements from the ER-2 Cloud Physics Lidar (CPL) system during CRYSTAL-FACE provide the basis for this work. While the CPL onboard the ER-2 aircraft was providing remote sensing measurements of cirrus clouds, the Cloud Particle Imager (CPI) onboard the WB-57 aircraft was flying inside those same clouds to sample particle sizes. The results of classifying particle shapes using the CPL data are compared to the in situ measurements made using the CPI , and there is found to be good agreement between the particle shape inferred from the CPL data and that actually measured by the CPI. If proven practical, application of this technique to spaceborne observations could lead to large-scale classification of cirrus cloud particle shapes.

  13. Caregiver talk to young Spanish-English bilinguals: comparing direct observation and parent-report measures of dual-language exposure.

    PubMed

    Marchman, Virginia A; Martínez, Lucía Z; Hurtado, Nereyda; Grüter, Theres; Fernald, Anne

    2017-01-01

    In research on language development by bilingual children, the early language environment is commonly characterized in terms of the relative amount of exposure a child gets to each language based on parent report. Little is known about how absolute measures of child-directed speech in two languages relate to language growth. In this study of 3-year-old Spanish-English bilinguals (n = 18), traditional parent-report estimates of exposure were compared to measures of the number of Spanish and English words children heard during naturalistic audio recordings. While the two estimates were moderately correlated, observed numbers of child-directed words were more consistently predictive of children's processing speed and standardized test performance, even when controlling for reported proportion of exposure. These findings highlight the importance of caregiver engagement in bilingual children's language outcomes in both of the languages they are learning.

  14. Morphological and histochemical observations on the crural gland-spur apparatus of the echidna (Tachyglossus aculeatus) together with comparative observations on the femoral gland-spur apparatus of the duckbilled platypus (Ornithorhyncus anatinus).

    PubMed

    Krause, William J

    2010-01-01

    The echidna and platypus have a crural/femoral gland that is linked by a large duct to a canalized, keratinous spur located on the medial side of the ankle. The echidna crural gland, like the femoral gland of the platypus, exhibits cyclic activity, being prominent in both monotremes when they are sexually active. In the present study, we compared the structure and histochemistry of these glands. During the active phase, the secretory epithelium forming the respective glands of both species increased in height and became packed with secretory granules that differed markedly in structure. Secretory granules of the echidna crural gland were electron dense and characterized by cores or areas of increased electron density. Those of the platypus were initially electron dense, but then became less dense and coalesced into irregular complexes of secretory material. Large cytoplasmic blebs extended from epithelial cell apices and appeared to be shed into the lumen, resulting in an apocrine mode of secretion. Exocytosis was also observed. A similar form of release of secretory product was not observed in the echidna. Secretory granules of both species were periodic acid-Schiff positive and stained for protein, suggesting that much of the secretory product was glycoprotein. Myoepithelial cells enveloped the secretory tubules of the platypus femoral gland, whereas they were not observed surrounding tubules comprising the echidna crural gland. During the quiescent phase, the epithelial cells of both species lost their secretory granules and decreased in height. As a result, the secretory tubules became smaller, intralobular connective tissue increased and the glands decreased in overall size.

  15. Comparing Dark Energy Survey and HST –CLASH observations of the galaxy cluster RXC J2248.7–4431: Implications for stellar mass versus dark matter

    DOE PAGES

    Palmese, A.; Lahav, O.; Banerji, M.; ...

    2016-08-20

    We derive the stellar mass fraction in the galaxy cluster RXC J2248.7–4431 observed with the Dark Energy Survey (DES) during the Science Verification period. We compare the stellar mass results from DES (five filters) with those from the Hubble Space Telescope Cluster Lensing And Supernova Survey (CLASH; 17 filters). When the cluster spectroscopic redshift is assumed, we show that stellar masses from DES can be estimated within 25 per cent of CLASH values. We compute the stellar mass contribution coming from red and blue galaxies, and study the relation between stellar mass and the underlying dark matter using weak lensingmore » studies with DES and CLASH. An analysis of the radial profiles of the DES total and stellar mass yields a stellar-to-total fraction of f* = (6.8 ± 1.7) × 10–3 within a radius of r200c ≃ 2 Mpc. Our analysis also includes a comparison of photometric redshifts and star/galaxy separation efficiency for both data sets. We conclude that space-based small field imaging can be used to calibrate the galaxy properties in DES for the much wider field of view. In conclusion, the technique developed to derive the stellar mass fraction in galaxy clusters can be applied to the ~100 000 clusters that will be observed within this survey and yield important information about galaxy evolution.« less

  16. Comparative Critical Discourse Analysis (CDA): Interplay of discourses (D/D1) as third grade urban and suburban science students engage in hypothesis formulation and observation

    NASA Astrophysics Data System (ADS)

    Mendoza, Carmen Irene Reyes

    This qualitative research project is a comparative analysis of Discourses (D/D1) while focused upon the science processes of hypothesis generation and observation in an urban versus suburban elementary science classroom. D designates the instructional and formal academic science Discourse and D1 represents the students' informal, social or home language D1iscourses. In particular, this research study is a critical discourse analysis that examines how the science processes of hypothesis formulation and observation are constituted through the interplay of classroom Discourses (D/D1) as two third grade science teachers teach the same kit-based, inquiry science lessons with their respective urban and suburban students. The research also considers ethnicity, social class, language, and the central role science teachers play mediating between children's everyday world and the world of science. Communicative approach and distinctive patterns of interaction between the European American teachers and their respective students are analyzed through a critical lens to examine underlying issues of equity and power embedded in the instructional Discourse of science. Critical Discourse Analysis (CDA) provides both the theoretical framework and analytical lens. The research informs development of linguistic-based "best" practices to contribute toward promoting greater science teacher awareness in creating linguistic environments that support all students' learning science Discourse and to serve as a springboard for future educational science researchers' use of CDA.

  17. Comparing Dark Energy Survey and HST-CLASH observations of the galaxy cluster RXC J2248.7-4431: implications for stellar mass versus dark matter

    NASA Astrophysics Data System (ADS)

    Palmese, A.; Lahav, O.; Banerji, M.; Gruen, D.; Jouvel, S.; Melchior, P.; Aleksić, J.; Annis, J.; Diehl, H. T.; Hartley, W. G.; Jeltema, T.; Romer, A. K.; Rozo, E.; Rykoff, E. S.; Seitz, S.; Suchyta, E.; Zhang, Y.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Doel, P.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Li, T. S.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Miller, C. J.; Miquel, R.; Nord, B.; Ogando, R.; Plazas, A. A.; Roodman, A.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, D.; Vikram, V.

    2016-12-01

    We derive the stellar mass fraction in the galaxy cluster RXC J2248.7-4431 observed with the Dark Energy Survey (DES) during the Science Verification period. We compare the stellar mass results from DES (five filters) with those from the Hubble Space Telescope Cluster Lensing And Supernova Survey (CLASH; 17 filters). When the cluster spectroscopic redshift is assumed, we show that stellar masses from DES can be estimated within 25 per cent of CLASH values. We compute the stellar mass contribution coming from red and blue galaxies, and study the relation between stellar mass and the underlying dark matter using weak lensing studies with DES and CLASH. An analysis of the radial profiles of the DES total and stellar mass yields a stellar-to-total fraction of f⋆ = (6.8 ± 1.7) × 10-3 within a radius of r200c ≃ 2 Mpc. Our analysis also includes a comparison of photometric redshifts and star/galaxy separation efficiency for both data sets. We conclude that space-based small field imaging can be used to calibrate the galaxy properties in DES for the much wider field of view. The technique developed to derive the stellar mass fraction in galaxy clusters can be applied to the ˜100 000 clusters that will be observed within this survey and yield important information about galaxy evolution.

  18. Extinction coefficients from lidar observations in ice clouds compared to in-situ measurements from the Cloud Integrating Nephelometer during CRYSTAL-FACE

    NASA Technical Reports Server (NTRS)

    Noel, Vincent; Winker, D. M.; Garrett, T. J.; McGill, M.

    2005-01-01

    This paper presents a comparison of volume extinction coefficients in tropical ice clouds retrieved from two instruments : the 532-nm Cloud Physics Lidar (CPL), and the in-situ probe Cloud Integrating Nephelometer (CIN). Both instruments were mounted on airborne platforms during the CRYSTAL-FACE campaign and took measurements in ice clouds up to 17km. Coincident observations from three cloud cases are compared : one synoptically-generated cirrus cloud of low optical depth, and two ice clouds located on top of convective systems. Emphasis is put on the vertical variability of the extinction coefficient. Results show small differences on small spatial scales (approx. 100m) in retrievals from both instruments. Lidar retrievals also show higher extinction coefficients in the synoptic cirrus case, while the opposite tendency is observed in convective cloud systems. These differences are generally variations around the average profile given by the CPL though, and general trends on larger spatial scales are usually well reproduced. A good agreement exists between the two instruments, with an average difference of less than 16% on optical depth retrievals.

  19. Comparative genotoxic and cytotoxic effects of the oral antidiabetic drugs sitagliptin, rosiglitazone, and pioglitazone in patients with type-2 diabetes: a cross-sectional, observational pilot study.

    PubMed

    Oz Gul, Ozen; Cinkilic, Nilufer; Gul, Cuma Bulent; Cander, Soner; Vatan, Ozgur; Ersoy, Canan; Yılmaz, Dilek; Tuncel, Ercan

    2013-09-18

    This cross-sectional, observational pilot study was designed to investigate the frequency of different endpoints of genotoxicity (sister-chromatid exchange, total chromosome aberrations, and micronucleus formation) and cytotoxicity (mitotic index, replication index, and nuclear division index) in the peripheral lymphocytes of patients with type-2 diabetes treated with different oral anti-diabetic agents for 6 months. A total of 104 patients who met the American Diabetes Association criteria for type-2 diabetes were enrolled in the study. Of the 104 patients, 33 were being treated with sitagliptin (100mg/day), 25 with pioglitazone (30mg/day), 22 with rosiglitazone (4mg/day), and 24 with medical nutrition therapy (control group). The results for all the genotoxicity endpoints were significantly different across the four study groups. Post hoc analysis revealed that the genotoxicity observed in the sitagliptin group was significantly higher than that observed in the medical nutrition therapy group, but lower than that occurring in subjects who received thiazolidinediones. All of the three cytotoxicity endpoints were significantly lower in patients treated by oral anti-diabetic agents compared with those who received medical nutrition therapy. However, the three indexes did not differ significantly in the sitagliptin, rosiglitazone, and pioglitazone groups. Taken together, these pilot data indicate that sitagliptin and thiazolidinediones may exert genotoxic and cytotoxic effects in patients with type-2 diabetes. Further investigations are necessary to clarify the possible long-term differences between oral anti-diabetic drugs in terms of genotoxicity and cytotoxicity, and how these can modulate the risk of developing diabetic complications in general and cancer in particular.

  20. Outcomes of mitral valve repair compared with replacement in patients undergoing concomitant aortic valve surgery: a meta-analysis of observational studies.

    PubMed

    Saurav, Alok; Alla, Venkata Mahesh; Kaushik, Manu; Hunter, Claire C; Mooss, Aryan V

    2015-09-01

    Long-term superiority of mitral valve (MV) repair compared with replacement is well established in degenerative MV disease. In rheumatic heart disease, its advantages are unclear and it is often performed in conjunction with aortic valve (AV) replacement. Herein, we performed a systematic review and meta-analysis comparing outcomes of MV repair vs replacement in patients undergoing concomitant AV replacement. PubMed, Cochrane and Web of Science databases were searched up to 25 January 2014 for English language studies comparing outcomes of MV repair vs replacement in patients undergoing simultaneous AV replacement. Data of selected studies were extracted. Study quality, publication bias and heterogeneity were assessed. Analysis was performed using a random effects model (meta-analysis of observational studies in epidemiology recommendation). A total of 1202 abstracts/titles were screened. Of these, 20 were selected for full text review and 8 studies (3924 patients) were included in the final analysis: 1255 underwent MV repair and 2669 underwent replacement. Late outcome data were available in seven studies (cumulative follow-up: 15 654 patient-years). The early (in hospital and up to 30 days post-surgery) mortality [risk ratio (RR): 0.68, 95% confidence interval (CI): 0.53-0.87, P = 0.003] and late (>30 days post-surgery) mortality (RR: 0.76, 95% CI: 0.64-0.90 P = 0.001) were significantly lower in the MV repair group compared with the MV replacement group. The MV reoperation rate (RR: 1.89, 95% CI: 0.87-4.10, P = 0.108), thromboembolism (including valve thrombosis) (RR: 0.65, 95% CI: 0.38-1.13, P = 0.128) and major bleeding rates (RR: 0.88, 95% CI: 0.49-1.57, P = 0.659) were found to be comparable between the two groups. In a separate analysis of studies with exclusively rheumatic patients (n = 1106), the early as well as late mortality benefit of MV repair was lost (RR: 0.92, 95% CI: 0.44-1.90, P = 0.81 and RR: 0.69, 95% CI: 0.39-1.22, P = 0.199, respectively

  1. Patient and carer experiences of clinical uncertainty and deterioration, in the face of limited reversibility: A comparative observational study of the AMBER care bundle

    PubMed Central

    Bristowe, Katherine; Carey, Irene; Hopper, Adrian; Shouls, Susanna; Prentice, Wendy; Caulkin, Ruth; Higginson, Irene J; Koffman, Jonathan

    2015-01-01

    Background: Clinical uncertainty is emotionally challenging for patients and carers and creates additional pressures for those clinicians in acute hospitals. The AMBER care bundle was designed to improve care for patients identified as clinically unstable, deteriorating, with limited reversibility and at risk of dying in the next 1–2 months. Aim: To examine the experience of care supported by the AMBER care bundle compared to standard care in the context of clinical uncertainty, deterioration and limited reversibility. Design: A comparative observational mixed-methods study using semi-structured qualitative interviews and a followback survey. Setting/participants: Three large London acute tertiary National Health Service hospitals. Nineteen interviews with 23 patients and carers (10 supported by AMBER care bundle and 9 standard care). Surveys completed by next of kin of 95 deceased patients (59 AMBER care bundle and 36 standard care). Results: The AMBER care bundle was associated with increased frequency of discussions about prognosis between clinicians and patients (χ2 = 4.09, p = 0.04), higher awareness of their prognosis by patients (χ2 = 4.29, p = 0.04) and lower clarity in the information received about their condition (χ2 = 6.26, p = 0.04). Although the consistency and quality of communication were not different between the two groups, those supported by the AMBER care bundle described more unresolved concerns about caring for someone at home. Conclusion: Awareness of prognosis appears to be higher among patients supported by the AMBER care bundle, but in this small study this was not translated into higher quality communication, and information was judged less easy to understand. Adequately powered comparative evaluation is urgently needed. PMID:25829443

  2. Do heads of government age more quickly? Observational study comparing mortality between elected leaders and runners-up in national elections of 17 countries

    PubMed Central

    Olenski, Andrew R; Abola, Matthew V

    2015-01-01

    Objectives To determine whether being elected to head of government is associated with accelerated mortality by studying survival differences between people elected to office and unelected runner-up candidates who never served. Design Observational study. Setting Historical survival data on elected and runner-up candidates in parliamentary or presidential elections in Australia, Austria, Canada, Denmark, Finland, France, Germany, Greece, Ireland, Italy, New Zealand, Norway, Poland, Spain, Sweden, United Kingdom, and United States, from 1722 to 2015. Participants Elected and runner-up political candidates. Main outcome measure Observed number of years alive after each candidate’s last election, relative to what would be expected for an average person of the same age and sex as the candidate during the year of the election, based on historical French and British life tables. Observed post-election life years were compared between elected candidates and runners-up, adjusting for life expectancy at time of election. A Cox proportional hazards model (adjusted for candidate’s life expectancy at the time of election) considered years until death (or years until end of study period for those not yet deceased by 9 September 2015) for elected candidates versus runners-up. Results The sample included 540 candidates: 279 winners and 261 runners-up who never served. A total of 380 candidates were deceased by 9 September 2015. Candidates who served as a head of government lived 4.4 (95% confidence interval 2.1 to 6.6) fewer years after their last election than did candidates who never served (17.8 v 13.4 years after last election; adjusted difference 2.7 (0.6 to 4.8) years). In Cox proportional hazards analysis, which considered all candidates (alive or deceased), the mortality hazard for elected candidates relative to runners-up was 1.23 (1.00 to 1.52). Conclusions Election to head of government is associated with a substantial increase in mortality risk compared

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

    SciTech Connect

    Rezai, Pedram; Yaghmai, Vahid; Tochetto, Sandra M.; Galizia, Mauricio S.; Miller, Frank H.; Mulcahy, Mary F.; Small, William

    2011-10-01

    Purpose: To depict treatment response to chemoradiotherapy by comparing tumor growth rate between treated and untreated patients and to compare depicted response with objective response according to the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 guideline. Methods and Materials: This Health Insurance Portability and Accountability Act-compliant, retrospective study was approved by the institutional review board. Volume doubling time (DT) of histologically confirmed locally advanced pancreatic adenocarcinoma was calculated in 16 patients treated with chemoradiotherapy and 10 untreated patients by incorporating interscan interval ({Delta}t) and tumor volume at baseline (V0) and follow-up (V1) obtained by semiautomated segmentation into the following equation: DT = {Delta}t . log 2/log (V1/V0). Reciprocal of doubling time (RDT), which is the linear representation of tumor growth rate, was calculated by use of the following equation: RDT = 365/DT. The lowest RDT value of 2.42 in untreated patients was considered as the cutoff value for depiction of treatment response. Depicted response rate was defined as the proportion of patients with an RDT value of less than 2.42. Depicted response was compared with objective response according to the RECIST 1.1 guideline. The significance level was set at p < 0.05. Results: There was a significant difference in mean RDT between treated (range, -7.12 to 3.27; mean, -1.27; median, -1.30) and untreated (range, 2.42 to 10.74; mean, 5.33; median, 4.26) patients (p < 0.05). Reciprocal of doubling time was less than 2.42 in 14 treated patients, which corresponded to a depicted response rate of 87.50% as opposed to the objective response rate of 18.75% according to the RECIST 1.1 guideline (p < 0.05) and carbohydrate antigen 19-9 response rate of 62.50% (p > 0.05). Carbohydrate antigen 19-9 response was concordant with RDT and RECIST response in 12 patients (75.00%) ({kappa}, 0.38) and 9 patients (56.25%) ({kappa}, 0

  4. Comparative effectiveness of adrenal sparing radical nephrectomy and non-adrenal sparing radical nephrectomy in clear cell renal cell carcinoma: Observational study of survival outcomes

    PubMed Central

    Nason, Gregory J.; Walsh, Leon G.; Redmond, Ciaran E.; Kelly, Niall P.; McGuire, Barry B.; Sharma, Vidit; Kelly, Michael E.; Galvin, David J.; Mulvin, David W.; Lennon, Gerald M.; Quinlan, David M.; Flood, Hugh D.; Giri, Subhasis K.

    2015-01-01

    Introduction: We compare the survival outcomes of patients with clear cell renal cell carcinoma (RCC) treated with adrenal sparing radical nephrectomy (ASRN) and non-adrenal sparing radical nephrectomy (NASRN). Methods: We conducted an observational study based on a composite patient population from two university teaching hospitals who underwent RN for RCC between January 2000 and December 2012. Only patients with pathologically confirmed RCC were included. We excluded patients undergoing cytoreductive nephrectomy, with loco-regional lymph node involvement. In total, 579 patients (ASRN = 380 and NASRN = 199) met our study criteria. Patients were categorized by risk groups (all stage, early stage and locally advanced RCC). Overall survival (OS) and cancer-specific survival (CSS) were analyzed for risk groups. Survival analysis was performed using Kaplan-Meier curves and Cox proportional hazards regression. Results: The median follow-up was 41 months (range: 12–157). There were significant benefits in OS (ASRN 79.5% vs. NASRN 63.3%; p = 0.001) and CSS (84.3% vs. 74.9%; p = 0.001), with any differences favouring ASRN in all stage. On multivariate analysis, there was a trend towards worse OS (hazard ratio [HR] 1.759, 95% confidence interval [CI] 0.943–2.309, p = 0.089) and CSS (HR 1.797, 95% CI 0.967–3.337, p = 0.064) in patients with NASRN (although not statistically significant). Of these patients, only 11 (1.9%) had adrenal involvement. Conclusions: The inherent limitations in our study include the impracticality of conducting a prospective randomized trial in this scenario. Our observational study with a 13-year follow-up suggests ASRN leads to better survival than NASRN. ASRN should be considered the gold standard in treating patients with RCC, unless it is contraindicated. PMID:26425218

  5. Retrospective observational case-control study comparing prehospital thrombolytic therapy for ST-elevation myocardial infarction with in-hospital thrombolytic therapy for patients from same area

    PubMed Central

    Chittari, M; Ahmad, I; Chambers, B; Knight, F; Scriven, A; Pitcher, D

    2005-01-01

    Design: Retrospective observational case-control study comparing patients with suspected acute myocardial infarction (AMI) treated with thrombolytic therapy in the prehospital environment with patients treated in hospital. Setting: Wyre Forest District and Worcestershire Royal Hospital, UK. Participants: (A) All patients who received prehospital thrombolytic therapy for suspected AMI accompanied by electrocardiographic features considered diagnostic. (B) Patients who received thrombolytic therapy after arrival at hospital for the same indication, matched with group A by age, gender and postcode. Main outcome measures: 1. Call to needle time 2. Percentage of patients treated within one hour of calling for medical help 3. Appropriateness of thrombolytic therapy 4. Safety of thrombolytic therapy Results: 1. The median call to needle time for patients treated before arriving in hospital (n = 27) was 40 minutes with an inter-quartile range 25–112 (mean 43 minutes). Patients from the same area who were treated in hospital (n = 27) had a median time of 106 minutes with an inter-quartile range 50–285 (mean 126 minutes). This represents a median time saved by prehospital treatment of 66 minutes. 2. 60 minutes after medical contact, 96 % of patients treated before arrival in hospital had received thrombolytic therapy; this compares with 4% of patients from similar areas treated in hospital. 3. Myocardial infarction was confirmed in 92% (25/27) of patients who received prehospital thrombolytic therapy and similarly 92% (25/27) of those given in-hospital thrombolytic therapy. 4. No major bleeding occurred in either group. Group A suffered fewer in-hospital deaths than group B (1 versus 4). Cardiogenic shock (3 patients) and ventricular arrhythmia (5 patients) were seen only in group B. Conclusion: Paramedic-delivered thrombolytic therapy can be delivered appropriately, safely, and effectively. Time gains are substantial and can meet the national targets for early

  6. Cyanoacrylate Injection Compared with Band Ligation for Acute Gastric Variceal Hemorrhage: A Meta-Analysis of Randomized Controlled Trials and Observational Studies

    PubMed Central

    Huai, Jiaping; Chen, Yanping

    2014-01-01

    Background. Cyanoacrylate injection (GVO) and band ligation (GVL) are effective treatments for gastric variceal hemorrhage. However, data on the optimal treatment are still controversial. Methods. For our overall analysis, relevant studies were identified from several databases. For each outcome, data were pooled using a fixed-effect or random-effects model according to the result of a heterogeneity test. Results. Seven studies were included. Compared with GVL, GVO was associated with increased likelihood of hemostasis of active bleeding (odds ratio [OR] = 2.32; 95% confidence interval [CI] = 1.19–4.51) and a longer gastric variceal rebleeding-free period (hazard ratio = 0.37; 95% CI = 0.24–0.56). No significant differences were observed between GVL and GVO for mortality (hazard ratio = 0.66; 95% CI = 0.43–1.02), likelihood of variceal obliteration (OR = 0.89; 95% CI = 0.52–1.54), number of treatment sessions required for complete variceal eradication (weighted mean difference = −0.45; 95% CI = −1.14–0.23), or complications (OR = 1.02; 95% CI = 0.48–2.19). Conclusion. GVO may be superior to GVL for achieving hemostasis and preventing recurrence of gastric variceal rebleeding but has no advantage over GVL for mortality and complications. Additional studies are warranted to enable definitive conclusions. PMID:24868204

  7. Comparative incidence of a first thrombotic event in purely obstetric antiphospholipid syndrome with pregnancy loss: the NOH-APS observational study.

    PubMed

    Gris, Jean-Christophe; Bouvier, Sylvie; Molinari, Nicolas; Galanaud, Jean-Philippe; Cochery-Nouvellon, Eva; Mercier, Erik; Fabbro-Peray, Pascale; Balducchi, Jean-Pierre; Marès, Pierre; Quéré, Isabelle; Dauzat, Michel

    2012-03-15

    The incidence of thrombosis in the purely obstetric form of antiphospholipid syndrome is uncertain. We performed a 10-year observational study of 1592 nonthrombotic women who had experienced 3 consecutive spontaneous abortions before the 10th week of gestation or 1 fetal death at or beyond the 10th week of gestation. We compared the frequencies of thrombotic events among women positive for antiphospholipid Abs (n = 517), women carrying the F5 6025 or F2 rs1799963 polymorphism (n = 279), and women with negative thrombophilia screening results (n = 796). The annual rates of deep vein thrombosis (1.46%; range, 1.15%-1.82%), pulmonary embolism (0.43%; range, 0.26%-0.66%), superficial vein thrombosis (0.44%; range, 0.28%-0.68%), and cerebrovascular events (0.32%; range, 0.18%-0.53%) were significantly higher in aPLAbs women than in the other groups despite low-dose aspirin primary prophylaxis. Women carrying 1 of the 2 polymorphisms did not experience more thrombotic events than women who screened negative for thrombophilia. Lupus anticoagulant was a risk factor for unprovoked proximal and distal deep and superficial vein thrombosis and women in the upper quartile of lupus anticoagulant activity had the highest risk. Despite data suggesting that aPLAbs may induce pregnancy loss through nonthrombotic mechanisms, women with purely obstetric antiphospholipid syndrome are at risk for thrombotic complications.

  8. Aorto-Uni-Iliac Stent Grafts with and without Crossover Femorofemoral Bypass for Treatment of Abdominal Aortic Aneurysms: A Parallel Observational Comparative Study

    PubMed Central

    Elkassaby, Mohammed; Alawy, Mahmoud; Ali, Mohamed Zaki; Tawfick, Wael A.; Sultan, Sherif

    2015-01-01

    We investigated the safety and efficacy of primary aorto-uni-iliac (AUI) endovascular aortic repair (EVAR) without fem-fem crossover in patients with abdominal aortic aneurysm (AAA) and concomitant aortoiliac occlusive disease. 537 EVARs were implemented between 2002 and 2015 in University Hospital Galway, a tertiary referral center for aortic surgery and EVAR. We executed a parallel observational comparative study between 34 patients with AUI with femorofemoral crossover (group A) and six patients treated with AUI but without the crossover (group B). Group B patients presented with infrarenal AAAs with associated total occlusion of one iliac axis and high comorbidities. Technical success was 97% (n = 33) in group A and 85% (n = 5) in group B (P = 0.31). Primary and assisted clinical success at 24 months were 88% (n = 30) and 12% (n = 4), respectively, in group A, and 85% (n = 5) and 15% (n = 1), respectively, in group B (P = 0.125). Reintervention rate was 10% (n = 3) in group A and 0% in group B (P = 0.084). No incidence of postoperative critical lower limb ischemia or amputations occurred in the follow-up period. AUI without crossover bypass is a viable option in selected cases. PMID:26770825

  9. Punctal plugs versus artificial tears for treating primary Sjögren's syndrome with keratoconjunctivitis SICCA: a comparative observation of their effects on visual function.

    PubMed

    Qiu, Weiqiang; Liu, Ziyuan; Ao, Mingxin; Li, Xuemin; Wang, Wei

    2013-10-01

    To compare the effects of treatment with punctal plugs versus artificial tears on visual function for primary Sjögren's syndrome with dry eye. Forty-two eyes of 42 patients with primary Sjögren's syndrome were enrolled and were allocated randomly into artificial tears (AT) group and punctal plugs (PP) group. Ocular Surface Disease Index (OSDI) was used, and fluorescent staining for tear film break-up time (BUT), the Schirmer test I (STI) and contrast sensitivity was performed before treatment and was repeated 3 months after treatment. A follow-up of 3 months was achieved in 40 eyes of 40 patients, including 19 eyes in artificial tears group and 21 eyes in punctal plugs group. Statistically significant improvements were observed in the OSDI scores (AT: 52.6 ± 5.7, 15.9 ± 4.2; PP: 55.8 ± 4.9, 15.1 ± 4.2), corneal fluorescein staining scores (AT: 2.60 ± 1.76, 0.30 ± 0.57; PP: 1.91 ± 1.60, 0.09 ± 0.29), STI (AT: 3.85 ± 2.03, 8.95 ± 2.72; PP: 3.36 ± 1.62, 11.41 ± 2.65), and BUT (AT: 2.60 ± 1.39, 6.00 ± 1.81; PP: 2.27 ± 1.12, 7.82 ± 1.84) after treatment compared to those of pre-treatment. The values of STI (AT: 5.10 ± 1.80; PP: 8.05 ± 1.53) and BUT (AT: 3.40 ± 1.31; PP: 5.68 ± 1.13) in punctal plugs group were significantly more improved than those in the artificial tears group. The medium- and high-level frequencies contrast sensitivities were greatly improved in simulated daylight, night, and glare disability conditions after treatment with artificial tears and punctal plugs. However, the changes in contrast sensitivity did not significantly differ between groups. Both artificial tears and punctal plugs relieved dry eye symptoms, repaired corneal lesions, enhanced tear film stability, and improved contrast sensitivity. Punctal plugs could improve tear film stability and elongate the BUT better than artificial tears.

  10. Observations and Processes Near the Snow-Air Interface: Insights Gained from New and Comparative Sensor Systems in View of Snow Surface Energy Balance Closure

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Selker, J. S.; Calaf-Bracons, M.; Parlange, M. B.

    2007-12-01

    Global warming drastically affects the seasonal snow cover in high altitude regions. The thermodynamic evolution of the snow pack is mainly controlled by the surface energy balance, however, most studies to date fail to close this budget on short time scales when using measurements of all its components. Also dynamic processes such as air movement in the snow pack associated with air exchange and the snow-atmosphere interface have to be taken into account. To investigate snow-atmosphere interaction, measurements of radiative and turbulent heat fluxes, and other meteorological quantities were obtained over a snow-covered glacier in the Swiss Alps during winter 2007. Humidity, air, surface, and snow temperature - quantities required to calculate energy fluxes for the surface energy budget - were measured with different sensors and techniques. Data revealed significant discrepancies between individual measurements at a location and time mainly due to solar heating of the sensors. We show that even shielded sensors overestimate air temperature during the day when compared to a radiation-independent reference sensor (sonic anemometer). Subsurface heat flux was determined from snow internal temperature and density data. High resolution temperature profiles were measured in the snow using traditional (thermocouple) and novel fiber optic distributed temperature instrumentation. To better understand the rate of gas exchange with the atmosphere controlling latent heat transport in the snow associated to phase changes (sublimation/deposition), air movement in the snow was investigated with using a new in-situ carbon monoxide trace gas measurement system providing high-resolution observation of snow transport process without gas extraction.

  11. WIN OVER study: Efficacy and safety of olmesartan in Indian hypertensive patients: Results of an open label, non-comparative, multi-centric, post marketing observational study

    PubMed Central

    Kumbla, D.K.; Kumar, S.; Reddy, Y.V.; Trailokya, A.; Naik, M.

    2014-01-01

    Background Hypertension is a global health problem. Multiple classes of drugs including angiotensin receptor blockers (ARBs) are available for the treatment of hypertension. Olmesartan is a relatively newer ARB used in hypertension management. Objective To assess the efficacy and safety of WIN-BP (Olmesartan 20 mg/40 mg) tablet in Indian patients with hypertension. Material and methods An open label, non-comparative, multi-centric, real world post marketing observational study included Indian adult hypertensive patients who were treated with olmesartan 20 mg/40 mg tablet once daily for six months. The primary outcome was reduction of systolic blood pressure (SBP) to <140 mmHg and diastolic BP (DBP) to <90 mmHg at 3 and 6 months after initiation of treatment with olmesartan. All reported adverse events were recorded. Results A total of 8940 patients were enrolled in this study. Baseline SBP of 164 mmHg was reduced to 153, 145, 134 and 130 mmHg at the end of 15 days, 1, 3 and 6 months respectively. Similarly, baseline DBP of 100 mmHg was reduced to 93, 89, 84 and 82 mmHg at the end of 15 days, 1, 3 and 6 months respectively. The reduction in both systolic and diastolic blood pressure from day 15 to month 6 was statistically significant (p < 0.0001) with olmesartan treatment. The percentage of responders for both systolic and diastolic blood pressure increased consistently from day 15 to month 6. Only 0.08% patients reported the adverse events. No serious adverse event was reported in the study. Conclusion Olmesartan 20 mg/40 mg is effective and well tolerated without any serious adverse events in patients with hypertension. PMID:24973841

  12. Comparing Parent-Child Interactions in the Clinic and at Home: An Exploration of the Validity of Clinical Behavior Observations Using Sequential Analysis

    ERIC Educational Resources Information Center

    Shriver, Mark D.; Frerichs, Lynae J.; Williams, Melissa; Lancaster, Blake M.

    2013-01-01

    Direct observation is often considered the "gold standard" for assessing the function, frequency, and intensity of problem behavior. Currently, the literature investigating the construct validity of direct observation conducted in the clinic setting reveals conflicting results. Previous studies on the construct validity of clinic-based…

  13. Comparing the observed differences in snowmelt energy fluxes during rain-on-snow and clear sky conditions at numerous open and forested sites

    NASA Astrophysics Data System (ADS)

    Garvelmann, J.; Pohl, S.; Weiler, M.

    2013-12-01

    The spatial and temporal variability of snowcover processes and the associated energy balance factors are still not well understood, especially in forested environments. A high-density network consisting of novel, low cost, standalone snow monitoring stations (SnoMoS) was deployed to measure snow depth and the meteorological variables controlling the available energy fluxes at the snow surface in the Black Forest, a typical mid latitude medium elevation mountain range (500-1500m). The winter periods in this environment are characterized by multiple snow accumulation and melt periods including frequent rain-on-snow events. A stratified sampling design was set-up to cover most of the elevation range and exposures in the study area. Furthermore SnoMoS pairs (forest/open) were installed to investigate the influence of the forest cover on the snow accumulation and melt processes. The meteorological variables measured in hourly intervals allowed for a continuous direct estimation of the individual surface energy balance components for different topographic situations, different vegetation covers, and a variety of climatic conditions. The study shows the relative importance and quantifies the contributions of the individual snowmelt energy balance components along with their respective spatial variability during a rain-on-snow event in December 2012 compared to clear sky snowmelt in early spring 2013 based on the data of 65 SnoMoS. The derived snowmelt energy balance for the 65 open and forested locations in the study area show the importance of the turbulent fluxes of sensible and latent heat accounting for, on average, 62% of the total melt energy available for snowmelt at open sites during a rain-on-snow event. At the forested sites, net longwave radiation (55%) and turbulent energy fluxes (32%) dominated snowmelt during this time. In contrast, during clear sky conditions net global radiation was dominating the energy balance at the open sites (92%) and forested sites

  14. Multidetector-Row Computed Tomography in the Evaluation of Transjugular Intrahepatic Portosystemic Shunt Performed with Expanded-Polytetrafluoroethylene-Covered Stent-Graft

    SciTech Connect

    Fanelli, Fabrizio Bezzi, Mario; Bruni, Antonio; Corona, Mario; Boatta, Emanuele; Lucatelli, Pierleone; Passariello, Roberto

    2011-02-15

    We assessed, in a prospective study, the efficacy of multidetector spiral computed tomography (MDCT) in the evaluation of transjugular intrahepatic portosystemic shunt (TIPS) patency in patients treated with the Viatorr (Gore, Flagstaff, AZ) expanded-polytetrafluoroethylene (e-PTFE)-covered stent-graft. Eighty patients who underwent TIPS procedure using the Viatorr self-expanding e-PTFE stent-graft were evaluated at follow-up of 1, 3, 6, and 12 months with clinical and laboratory tests as well as ultrasound-color Doppler (USCD) imaging. In case of varices, upper gastrointestinal endoscopy was also performed. In addition, the shunt was evaluated using MDCT at 6 and 12 months. In all cases of abnormal findings and discrepancy between MDCT and USCD, invasive control venography was performed. MDCT images were acquired before and after injection of intravenous contrast media on the axial plane and after three-dimensional reconstruction using different algorithms. MDCT was successfully performed in all patients. No artefacts correlated to the Viatorr stent-graft were observed. A missing correlation between UCSD and MDCT was noticed in 20 of 80 (25%) patients. Invasive control venography confirmed shunt patency in 16 (80%) cases and shunt malfunction in 4 (20%) cases. According to these data, MDCT sensitivity was 95.2%; specificity was 96.6%; and positive (PPV) and negative predictive values (NPV) were 90.9 and 98.2%, respectively. USCD sensitivity was 90%; specificity was 75%; and PPV and NPV were 54.5 and 95.7%, respectively. A high correlation (K value = 0.85) between MDCT and invasive control venography was observed. On the basis of these results, MDCT shows superior sensitivity and specificity compared with USCD in those patients in whom TIPS was performed with the Viatorr stent-graft. MDCT can be considered a valid tool in the follow-up of these patients.

  15. The Comparative Characteristic of Components in the Iiib-Iii Pairs According to the Observation Data Obtained by Radio Telescope URAN-2

    NASA Astrophysics Data System (ADS)

    Brazhenko, A. I.; Melnik, V. N.; Konovalenko, A. A.; Dorovskiy, V. V.; Vashchishin, R. V.; Frantsuzenko, A. V.; Rucker, G.

    In this paper we analyze the properties of type IIIb and type III bursts in IIIb-III pairs observed by radio telescope URAN-2 at frequencies 16-32 MHz. We discuss pro and contra of harmonic phenomenon of decameter IIIb-III pairs.

  16. Comparative study of the Martian suprathermal electron depletions based on Mars Global Surveyor, Mars Express, and Mars Atmosphere and Volatile EvolutioN mission observations

    NASA Astrophysics Data System (ADS)

    Steckiewicz, M.; Garnier, P.; André, N.; Mitchell, D. L.; Andersson, L.; Penou, E.; Beth, A.; Fedorov, A.; Sauvaud, J.-A.; Mazelle, C.; Brain, D. A.; Espley, J. R.; McFadden, J.; Halekas, J. S.; Larson, D. E.; Lillis, R. J.; Luhmann, J. G.; Soobiah, Y.; Jakosky, B. M.

    2017-01-01

    Nightside suprathermal electron depletions have been observed at Mars by three spacecraft to date: Mars Global Surveyor, Mars Express, and the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. This spatial and temporal diversity of measurements allows us to propose here a comprehensive view of the Martian electron depletions through the first multispacecraft study of the phenomenon. We have analyzed data recorded by the three spacecraft from 1999 to 2015 in order to better understand the distribution of the electron depletions and their creation mechanisms. Three simple criteria adapted to each mission have been implemented to identify more than 134,500 electron depletions observed between 125 and 900 km altitude. The geographical distribution maps of the electron depletions detected by the three spacecraft confirm the strong link existing between electron depletions and crustal magnetic field at altitudes greater than 170 km. At these altitudes, the distribution of electron depletions is strongly different in the two hemispheres, with a far greater chance to observe an electron depletion in the Southern Hemisphere, where the strongest crustal magnetic sources are located. However, the unique MAVEN observations reveal that below a transition region near 160-170 km altitude the distribution of electron depletions is the same in both hemispheres, with no particular dependence on crustal magnetic fields. This result supports the suggestion made by previous studies that these low-altitudes events are produced through electron absorption by atmospheric CO2.

  17. The ACS LCID Project. XI. On the Early Time Resolution of SFHs of Local Group Dwarf Galaxies: Comparing the Effects of Reionization in Models with Observations

    NASA Astrophysics Data System (ADS)

    Aparicio, Antonio; Hidalgo, Sebastian L.; Skillman, Evan; Cassisi, Santi; Mayer, Lucio; Navarro, Julio; Cole, Andrew; Gallart, Carme; Monelli, Matteo; Weisz, Daniel; Bernard, Edouard; Dolphin, Andrew; Stetson, Peter

    2016-05-01

    The analysis of the early star formation history (SFH) of nearby galaxies, obtained from their resolved stellar populations, is relevant as a test for cosmological models. However, the early time resolution of observationally derived SFHs is limited by several factors. Thus, direct comparison of observationally derived SFHs with those derived from theoretical models of galaxy formation is potentially biased. Here we investigate and quantify this effect. For this purpose, we analyze the duration of the early star formation activity in a sample of four Local Group dwarf galaxies and test whether they are consistent with being true fossils of the pre-reionization era; i.e., if the quenching of their star formation occurred before cosmic reionization by UV photons was completed. Two classical dSph (Cetus and Tucana) and two dTrans (LGS-3 and Phoenix) isolated galaxies with total stellar masses between 1.3× {10}6 and 7.2× {10}6 {M}⊙ have been studied. Accounting for time resolution effects, the SFHs peak as much as 1.25 Gyr earlier than the optimal solutions. Thus, this effect is important for a proper comparison of model and observed SFHs. It is also shown that none of the analyzed galaxies can be considered a true fossil of the pre-reionization era, although it is possible that the outer regions of Cetus and Tucana are consistent with quenching by reionization. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #10505.

  18. Comparative Analysis of Two Inquiry Observational Protocols: Striving to Better Understand the Quality of Teacher-Facilitated Inquiry-Based Instruction

    ERIC Educational Resources Information Center

    Marshall, Jeff C.; Smart, Julie; Lotter, Christine; Sirbu, Cristina

    2011-01-01

    With inquiry being one of the central tenets of the national and most state standards, it is imperative that we have a solid means to measure the quality of inquiry-based instruction being led in classrooms. Many instruments are available and used for this purpose, but many are either invalid or too global. This study sought to compare two…

  19. Evaluation of spectroscopic databases through radiative transfer simulations compared to observations. Application to the validation of GEISA 2015 with IASI and TCCON

    NASA Astrophysics Data System (ADS)

    Armante, Raymond; Scott, Noelle; Crevoisier, Cyril; Capelle, Virginie; Crepeau, Laurent; Jacquinet, Nicole; Chédin, Alain

    2016-09-01

    The quality of spectroscopic parameters that serve as input to forward radiative transfer models are essential to fully exploit remote sensing of Earth atmosphere. However, the process of updating spectroscopic databases in order to provide the users with a database that insures an optimal characterization of spectral properties of molecular absorption for radiative transfer modeling is challenging. The evaluation of the databases content and the underlying choices made by the managing team is thus a crucial step. Here, we introduce an original and powerful approach for evaluating spectroscopic parameters: the Spectroscopic Parameters And Radiative Transfer Evaluation (SPARTE) chain. The SPARTE chain relies on the comparison between forward radiative transfer simulations made by the 4A radiative transfer model and observations of spectra made from various observations collocated over several thousands of well-characterized atmospheric situations. Averaging the resulting 'calculated-observed spectral' residuals minimizes the random errors coming from both the radiometric noise of the instruments and the imperfect description of the atmospheric state. The SPARTE chain can be used to evaluate any spectroscopic databases, from the visible to the microwave, using any type of remote sensing observations (ground-based, airborne or space-borne). We show that the comparison of the shape of the residuals enables: (i) identifying incorrect line parameters (line position, intensity, width, pressure shift, etc.), even for molecules for which interferences between the lines have to be taken into account; (ii) proposing revised values, in cooperation with contributing teams; and (iii) validating the final updated parameters. In particular, we show that the simultaneous availability of two databases such as GEISA and HITRAN helps identifying remaining issues in each database. The SPARTE chain has been here applied to the validation of the update of GEISA-2015 in 2 spectral regions

  20. A pilot study comparing observational and questionnaire measures as surrogates of residential pesticide exposures among residents impacted by the Ecuadorian Cut-Flower Farming industry

    PubMed Central

    Handal, Alexis J.; McGough-Maduena, Alison; Páez, Maritza; Skipper, Betty; Rowland, Andrew S.; Fenske, Richard A.; Harlow, Siobán D.

    2014-01-01

    Self-reported measures of residential pesticide exposure are commonly used in epidemiological studies, especially when financial and logistical resources are limited. However, self-reporting is prone to misclassification bias. This pilot study assesses the agreement between self-report of take-home pesticide exposure with direct observation measures, in an agricultural region of Ecuador, as a cross-validation method in 26 participants (16 rose workers and 10 controls), with percent agreement and kappa statistics calculated. Proximity of homes to nearby flower farms was found to have only fair agreement (kappa = 0.35). The use of discarded plastics (kappa = 0.06) and wood (kappa = 0.13) were found to have little agreement. Results indicate that direct observation or measurement may provide more accurate appraisals of residential exposures, such as proximity to industrial farmland and the use of discarded materials obtained from the flower farms. PMID:24455979

  1. Insights into Focused Fluid Conduit Formation from Comparing Seismic Chimneys and Pipes with Field Observations of Fluid Flow Manifestations in the Colorado Plateau

    NASA Astrophysics Data System (ADS)

    Karstens, J.; Berndt, C.

    2014-12-01

    The understanding of focused fluid flow in sedimentary basins builds on field geological observations and the interpretation of reflection seismic data, where fluid conduits manifest as anomalous amplitude patterns known as seismic chimneys or pipes. Seismic data is the most effective method for the analysis of entire fluid flow systems by constraining subsurface geometries, fluid accumulations and permeability barriers, but seismic data cannot provide information about the internal architecture, interaction with the bedrock and flow processes due to its coarse resolution. Field geological investigations of fluid conduit outcrops are capable of filling observation gaps on a sub-seismic scale and help constrain formation dynamics as well as hydraulic properties of fluid conduits and the bedrock. Here, we show that it is possible to correlate specific amplitude patterns of seismic chimneys with field observation of focused fluid conduits from the Colorado Plateau. The migrating fluids (gas, water, fluidized sediment) and their formation dynamics, which can be associated with different types of conduits (fractures, fluidizations, injections), result in distinguishable seismic signatures. These constrains improve the qualitative interpretation of seismic chimneys by adding information about migration and formation characteristics. A further integration of field geological and seismic investigation of focused fluid flow structures may help to quantify their hydraulic properties and how these evolve with time, which has important implications for the hydrocarbon prospection and the subsurface storage of wastewater and CO2.

  2. Low-Volume Brachial Plexus Block Providing Surgical Anesthesia for Distal Arm Surgery Comparing Supraclavicular, Infraclavicular, and Axillary Approach: A Randomized Observer Blind Trial

    PubMed Central

    Vazin, Mojgan; Jensen, Kenneth; Kristensen, Danja L.; Hjort, Mathias; Tanggaard, Katrine; Karmakar, Manoj K.; Bendtsen, Thomas F.

    2016-01-01

    Background. Distal arm surgery is widely performed under regional anesthesia with brachial plexus block. The preponderance of evidence for the efficacy relies upon injection of local anesthetic in excess of 30 mL. We aimed to compare three different ultrasound-guided brachial plexus block techniques restricting the total volume to 20 mL. Methods. 120 patients were prospectively randomized to ultrasound-guided brachial plexus block with 20 mL ropivacaine 0.75% at either the supraclavicular, infraclavicular, or axillary level. Multiinjection technique was performed with all three approaches. Primary outcome measure was performance time. Results. Performance time and procedural pain were similar between groups. Needle passes and injection numbers were significantly reduced in the infraclavicular group (P < 0.01). Nerve visibility was significantly reduced in the axillary group (P = 0.01). Success-rate was significantly increased in the supraclavicular versus the axillary group (P < 0.025). Total anesthesia-related time was significantly reduced in the supraclavicular compared to the infraclavicular group (P < 0.01). Block duration was significantly increased in the infraclavicular group (P < 0.05). No early adverse effects occurred. Conclusion. Supraclavicular and infraclavicular blocks exhibited favorable characteristics compared to the axillary block. Supraclavicular brachial plexus block with the multiinjection intracluster technique exhibited significantly reduced total anesthesia-related time and higher success rate without any early adverse events. PMID:27990435

  3. Long-Term Changes in Lower Tropospheric Baseline Ozone Concentrations:. [Comparing Chemistry-Climate Models and Observations at Northern Mid-Latitudes

    NASA Technical Reports Server (NTRS)

    Parrish, D. D.; Lamarque, J.-F.; Naik, V.; Horowitz, L.; Shindell, D. T.; Staehelin, J.; Derwent, R.; Cooper, O. R.; Tanimoto, H.; Volz-Thomas, A.; Gilge, S.; Scheel, H.-E.; Steinbacher, M.; Frohlich, M.

    2014-01-01

    Two recent papers have quantified long-term ozone (O3) changes observed at northernmidlatitude sites that are believed to represent baseline (here understood as representative of continental to hemispheric scales) conditions. Three chemistry-climate models (NCAR CAM-chem, GFDL-CM3, and GISS-E2-R) have calculated retrospective tropospheric O3 concentrations as part of the Atmospheric Chemistry and Climate Model Intercomparison Project and Coupled Model Intercomparison Project Phase 5 model intercomparisons. We present an approach for quantitative comparisons of model results with measurements for seasonally averaged O3 concentrations. There is considerable qualitative agreement between the measurements and the models, but there are also substantial and consistent quantitative disagreements. Most notably, models (1) overestimate absolute O3 mixing ratios, on average by approximately 5 to 17 ppbv in the year 2000, (2) capture only approximately 50% of O3 changes observed over the past five to six decades, and little of observed seasonal differences, and (3) capture approximately 25 to 45% of the rate of change of the long-term changes. These disagreements are significant enough to indicate that only limited confidence can be placed on estimates of present-day radiative forcing of tropospheric O3 derived from modeled historic concentration changes and on predicted future O3 concentrations. Evidently our understanding of tropospheric O3, or the incorporation of chemistry and transport processes into current chemical climate models, is incomplete. Modeled O3 trends approximately parallel estimated trends in anthropogenic emissions of NO(sub x), an important O3 precursor, while measured O3 changes increase more rapidly than these emission estimates.

  4. An observer-blind randomised parallel group study comparing the efficacy and tolerability of tenoxicam and piroxicam in the treatment of post-operative pain after oral surgery.

    PubMed

    Roelofse, J A; Swart, L C; Stander, I A

    1996-11-01

    Tenoxicam and piroxicam were compared for analgesic efficacy in 58 patients undergoing removal of bilateral impacted third molar teeth, under general anaesthesia. Pain intensity was assessed over a 7 day period by the patient using verbal and visual analogue scales. The patients received one hour pre-operatively dormicum 7.5 mg orally and either tenoxicam 40 mg or piroxicam 40 mg rectally. This was followed by tenoxicam 20 mg daily in effervescent form, or piroxicam 20 mg daily in despersible tablet form for 7 days. Surgical and anaesthetic techniques were standardized for all patients. Therapeutic gain was assessed by comparing hourly pain levels 4 hours post-operatively and then twice daily for 7 days. Trismus was evaluated pre-operatively, at one hour, 24 hours and 7 days post-operatively. Analysis of the results showed a statistical significant difference between the treatment groups only 4 hours post-operatively, patients in the tenoxicam group experiencing less pain than those in the piroxicam group (p = < 0.05).

  5. The European-Alpine collision during the last 45Myrs - constraints obtained from comparing 3-D numerical subduction models and tomographic observations

    NASA Astrophysics Data System (ADS)

    Morra, G.; Regenauer-Lieb, K.; Kissling, E.; Lippitsch, R.

    2003-04-01

    We analyze the interaction of Adriatic and the European Plates driven self-consistently by slab pull in order to seperate out the roles of (1) intrinsic dynamics of the slab driven Adriatic microplate system, (2) interaction with the subducting European plate, (3) the pushing African plate and (4) the feedback of slab induced flow within the mantle. The simulation is based on a new three-dimensional solid-fluid solver that we developed for plate tectonics reconstruction. The method embeds a Lagrangian Finite Element model of the lithosphere into a creeping medium (Stokeslet Method see poster) representing the mantle. Density inhomogeneities within the subducting plate are inserted to obtain realistic reconstructions of tomographically observed slab lengths in both the Central Mediterranean and European-Alpine subduction systems. In a first step we analyse the system in the absence of the African convergence. With this asssumption the model is only driven by gravity and thus gives an insight into the internal dynamics of the Central-European microplate evolution. In a second step we add the African convergence as a large scale distributed force. Using this method the mechanical origin of rotation of the Adriatic microplate in the vise of the African-European convergence can be analysed and its impact on the collision in the Alps derived. While our solution space is a first set, the aim of the analysis is to obtain constraints of the history of Adriatic-European collision using the new solver as a toolbox. The method has the potential to act as a filter between geological observation, tomographic data and mechanical constraints within the framework of a dynamic 3-D plate tectonic evolution.

  6. Variability in Antarctic ozone loss in the last decade (2004-2013): high-resolution simulations compared to Aura MLS observations

    NASA Astrophysics Data System (ADS)

    Kuttippurath, J.; Godin-Beekmann, S.; Lefèvre, F.; Santee, M. L.; Froidevaux, L.; Hauchecorne, A.

    2015-09-01

    A detailed analysis of the polar ozone loss processes during 10 recent Antarctic winters is presented with high-resolution MIMOSA-CHIM (Modèle Isentrope du transport Méso-échelle de l'Ozone Stratosphérique par Advection avec CHIMie) model simulations and high-frequency polar vortex observations from the Aura microwave limb sounder (MLS) instrument. The high-frequency measurements and simulations help to characterize the winters and assist the interpretation of interannual variability better than either data or simulations alone. Our model results for the Antarctic winters of 2004-2013 show that chemical ozone loss starts in the edge region of the vortex at equivalent latitudes (EqLs) of 65-67° S in mid-June-July. The loss progresses with time at higher EqLs and intensifies during August-September over the range 400-600 K. The loss peaks in late September-early October, when all EqLs (65-83° S) show a similar loss and the maximum loss (> 2 ppmv - parts per million by volume) is found over a broad vertical range of 475-550 K. In the lower stratosphere, most winters show similar ozone loss and production rates. In general, at 500 K, the loss rates are about 2-3 ppbv sh-1 (parts per billion by volume per sunlit hour) in July and 4-5 ppbv sh-1 in August-mid-September, while they drop rapidly to 0 by mid-October. In the middle stratosphere, the loss rates are about 3-5 ppbv sh-1 in July-August and October at 675 K. On average, the MIMOSA-CHIM simulations show that the very cold winters of 2005 and 2006 exhibit a maximum loss of ~ 3.5 ppmv around 550 K or about 149-173 DU over 350-850 K, and the warmer winters of 2004, 2010, and 2012 show a loss of ~ 2.6 ppmv around 475-500 K or 131-154 DU over 350-850 K. The winters of 2007, 2008, and 2011 were moderately cold, and thus both ozone loss and peak loss altitudes are between these two ranges (3 ppmv around 500 K or 150 ± 10 DU). The modeled ozone loss values are in reasonably good agreement with those estimated from

  7. Near-Infrared Faint Galaxies in the Subaru Deep Field: Comparing the Theory with Observations for Galaxy Counts, Colors, and Size Distributions to K ~ 24.5

    NASA Astrophysics Data System (ADS)

    Totani, Tomonori; Yoshii, Yuzuru; Maihara, Toshinori; Iwamuro, Fumihide; Motohara, Kentaro

    2001-10-01

    Galaxy counts in the K band, (J-K) colors, and apparent size distributions of faint galaxies in the Subaru Deep Field (SDF) down to K~24.5 were studied in detail. Special attention has been paid to take into account various selection effects, including the cosmological dimming of surface brightness, to avoid any systematic bias that may be the origin of controversy in previously published results. We also tried to be very careful about systematic model uncertainties; we present a comprehensive survey of these systematic uncertainties and dependence on various parameters, and we have shown that the dominant factors to determine galaxy counts in this band are cosmology and number evolution. We found that the pure luminosity evolution (PLE) model is very consistent with all the SDF data down to K~22.5, without any evidence for number or size evolution in a low-density, Λ-dominated flat universe, which is now favored by various cosmological observations. On the other hand, a number evolution of galaxies with η~2, when invoked as the luminosity conserving mergers as φ*~(1+z)η and L*~(1+z)-η for all types of galaxies, is necessary to explain the data in the Einstein-de Sitter universe. If the popular Λ-dominated universe is taken for granted, our result then gives a strong constraint on the number evolution of giant elliptical or early-type galaxies to z~1-2 that must be met by any models in the hierarchically clustering universe, since such galaxies are the dominant population in this magnitude range (K<~22.5). A number evolution with η~1 is already difficult to reconcile with the data in this universe. On the other hand, number evolution of late-type galaxies and/or dwarf galaxies, which has been suggested by previous studies of optical galaxies, is allowed from the data. In the fainter magnitude range of K>~22.5, we found a slight excess of observed counts over the prediction of the PLE model when elliptical galaxies are treated as a single population. We

  8. Comparing Local-Time and Storm-Phase Distributions of EMIC Waves Observed by Van Allen Probes A, GOES-13, and Halley, Antarctica

    NASA Astrophysics Data System (ADS)

    Ohnsted, M.; Engebretson, M. J.; Posch, J. L.; Lessard, M.; Singer, H. J.; Kletzing, C.; Smith, C. W.; Horne, R. B.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) waves are expected to be highly efficient in depleting the ring current and in removing outer radiation belt electrons. However, the distribution of these waves in subauroral regions has not been well characterized. In this study we present 0-5 Hz magnetic field data from the Van Allen Probes A (RBSP A) spacecraft (in elliptical equatorial orbit with apogee at 5.8 RE), 0-1 Hz data from GOES-13 (in geosynchronous orbit), and 0-5 Hz data from Halley, Antarctica (L ~4.6), during the first full local-time precession of the Van Allen Probes from October 2012 through July 2014. The considerably different hourly local time vs. L distributions observed point to distinct locations and geomagnetic activity-dependent patterns of EMIC wave activity. GOES-13 wave occurrences exhibited a broad peak in the noon-to-dusk sector. He+ band events peaked near dusk, while H+ band waves peaked near noon, with a secondary peak centered near dawn. More EMIC waves occurred during storm main phase in the He+ band (5%) than in the H+ band (1%), and 80% and 89% of the He+ and H+ band waves, respectively, occurred under late storm recovery or quiet conditions. During all storm phases the local time occurrence patterns of < 0.4 Hz and 0.4-1.0 Hz events at Halley resembled those of He+ and H+ band waves, respectively, at GOES-13. The relatively few wave events at Halley with f > 1.0 Hz occurred at all local times, but with a modest, broad peak near dawn. Roughly 90% of both the 1570 Halley events < 1.0 Hz and the 142 Halley events > 1.0 Hz occurred during late storm recovery and quiet conditions. Events during compressions at GOES-13 (10%), Halley (6%), and RBSP A (6%) peaked near local noon, but with a secondary peak near midnight. Waves observed by RBSP A were distributed rather evenly in local time in all L shell ranges between 3 and 6, and the percentage occurring during late storm recovery or quiet conditions was only 65%. We interpret the difference in

  9. Sagittal abdominal diameter is a more independent measure compared with waist circumference to predict arterial stiffness in subjects with type 2 diabetes - a prospective observational cohort study

    PubMed Central

    2013-01-01

    Background Anthropometric measurements are useful in clinical practice since they are non-invasive and cheap. Previous studies suggest that sagittal abdominal diameter (SAD) may be a better measure of visceral fat depots. The aim of this study was to prospectively explore and compare how laboratory and anthropometric risk markers predicted subclinical organ damage in 255 patients, with type 2 diabetes, after four years. Methods Baseline investigations were performed in 2006 and were repeated at follow-up in 2010. Carotid intima-media thickness (IMT) was evaluated by ultrasonography and aortic pulse wave velocity (PWV) was measured with applanation tonometry over the carotid and femoral arteries at baseline and at follow-up in a cohort of subjects with type 2 diabetes aged 55–65 years old. Results There were significant correlations between apolipoprotein B (apoB) (r = 0.144, p = 0.03), C - reactive protein (CRP) (r = 0.172, p = 0.009) at baseline and IMT measured at follow-up. After adjustment for sex, age, treatment with statins and Hba1c, the associations remained statistically significant. HbA1c, total cholesterol or LDL-cholesterol did not correlate to IMT at follow-up. Baseline body mass index (BMI) (r = 0.130, p = 0.049), waist circumference (WC) (r = 0.147, p = 0.027) and sagittal Abdominal Diameter (SAD) (r = 0.184, p = 0.007) correlated to PWV at follow-up. Challenged with sex, SBP and HbA1c, the association between SAD, not WC nor BMI, and PWV remained statistically significant (p = 0.036). In a stepwise linear regression, entering both SAD and WC, the association between SAD and PWV was stronger than the association between WC and PWV. Conclusions We conclude that apoB and CRP, but not LDL-cholesterol predicted subclinical atherosclerosis. Furthermore, SAD was more independent in predicting arterial stiffness over time, compared with WC, in middle-aged men and women with type 2 diabetes. PMID:23536999

  10. Growth data of underprivileged children living in rural areas of Chin State, Burma/Myanmar, compared to the WHO reference growth standards: an observational study

    PubMed Central

    Prenkert, Malin; Ehnfors, Margareta

    2016-01-01

    Objectives To explore growth data (height-for-age, weight-for-age and BMI-for-age) of children living in poor socioeconomic conditions in rural areas of Chin State, Burma/Myanmar; and to compare these data with the growth and development z-score (GDZ) values for school-aged children and adolescents, provided by the WHO. Setting A support and educational programme, run by the Swedish association Chin Development and Research Society (CDRS), was carried out among underprivileged school-aged children, unable to attend school without economic and practical support, living in villages and remote areas in Chin State. Participants Community leaders who were well familiar with the citizens in the community identified children in need of this support. Other community members could also suggest or apply for this. The sample includes all participating children in the CDRS programme at the time of the data collection in six townships. The children were placed in host families, close to a suitable school. Two samples with a total of 639 children from 144 villages and remote areas were obtained: 1. Children in the CDRS Chin Programme (CCP) (2007–2010) comprised 558 children: 50% girls and boys. 2. Children in the Chin Society (CCS) (2010) comprised 81 children: 44% girls and 56% boys. Primary outcome measures Growth data. Results All growth data from both groups deviated significantly from the WHO standard references (p≤0.001). The prevalence of stunting (height-for-age ≤–2SD) was 52% among girls and 68% among boys. High levels of wasting (weight-for-age ≤–2SD) were found among girls 29% and boys 36% aged 5–10 years. In addition, severe thinness (BMI-for-age ≤–2SD) was found among girls 31% and boys 44%, all results to be compared to the expected 2.27%. Conclusions Many more than expected—according to the WHO reference values—in CCP and CCS suffered from stunting, wasting and thinness. PMID:26787249

  11. Observations on cattle schistosomiasis in the Sudan, a study in comparative medicine. III. Field testing of an irradiated Schistosoma bovis vaccine

    SciTech Connect

    Majid, A.A.; Bushera, H.O.; Saad, A.M.; Hussein, M.F.; Taylor, M.G.; Dargie, J.D.; Marshall, T.F.; Nelson, G.S.

    1980-05-29

    Previous work has shown that cattle can acquire a strong resistance to Schistosoma bovis infection following repeated natural exposure. Partial resistance to a laboratory challenge with S. bovis has also been demonstrated in calves after immunization with an irradiated schistosomular or cercarial vaccine. The aim of the present study was to see whether this type of caccine could protect calves under the very different conditions of natural exposure to S. bovis in the field. Thirty 6- to 9-month-old calves were each immunized with 10,000 irradiated S. bovis schistosomula by intramuscular injection and 8 weeks later were released into an enzootic area along with 30 unvaccinated animals. The calves were followed up for 10 months, during which period protection was evidenced by a lower mortality rate, a slower rate of acquisition of infection, and lower fecal egg counts in the vaccinated calves. Necropsy of the survivors showed 60 to 70% reductions in worm and tissue egg counts of the vaccinated calves as compared to those not vaccinated.

  12. An observational retrospective/horizontal study to compare oxygen-ozone therapy and/or global postural re-education in complicated chronic low back pain

    PubMed Central

    Apuzzo, Dario; Giotti, Chiara; Pasqualetti, Patrizio; Ferrazza, Paolo; Soldati, Paola; Zucco, Gesualdo M.

    2014-01-01

    Summary Acute low back pain (LBP) is the fifth most common reason for physician visits and about nine out of ten adults experience back pain at some point in their life. In a large number of patients LBP is associated with disc herniation (DH). Recently, oxygen-ozone (O2O3) therapy has been used successfully in the treatment of LBP, reducing pain after the failure of other conservative treatments. The aim of this study was to assess the effects of O2O3 therapy in back pain rehabilitation, comparing three groups of patients suffering from chronic back pain associated with DH submitted to three different treatments: intramuscular O2O3 infiltrations, global postural re-education (GPR), or a combination of the two (O2O3+GPR). The data show that pain severity before treatment was significantly lower in the patients treated with GPR alone (VAS score 7.4) than in the O2O3+GPR patients (VAS score 8.5) and the O2O3 patients (VAS score 8.6). At the end of treatment, pain severity was lower in the O2O3 patients than in the GPR-alone patients. After some years of follow-up only the difference between O2O3+GPR and GPR-alone remained significant. PMID:25014047

  13. Comparing human papillomavirus prevalences in women with normal cytology or invasive cervical cancer to rank genotypes according to their oncogenic potential: a meta-analysis of observational studies

    PubMed Central

    2013-01-01

    Background Mucosal human papillomavirus (HPV) infection is a necessary cause of cervical cancer. Vaccine and non-vaccine genotype prevalences may change after vaccine introduction. Therefore, it appears essential to rank HPV genotypes according to their oncogenic potential for invasive cervical cancer, independently of their respective prevalences. Methods We performed meta-analyses of published observational studies and estimated pooled odds ratios with random-effects models for 32 HPV genotypes, using HPV-16 as the reference. Results Twenty-seven studies yielded 9,252 HPV-infected women: 2,902 diagnosed with invasive cervical cancer and 6,350 with normal cytology. Expressed as (odds ratio [95% confidence interval]), HPV-18 (0.63 [0.51, 0.78]) ranked closest to HPV-16, while other genotypes showed continuously decreasing relative oncogenic potentials: HPV-45 (0.35 [0.22, 0.55]), HPV-69 (0.28 [0.09, 0.92]), HPV-58 (0.24 [0.15, 0.38]), HPV-31 (0.22 [0.14, 0.35]), HPV-33 (0.22 [0.12, 0.38]), HPV-34 (0.21 [0.06, 0.80]), HPV-67 (0.21 [0.06, 0.67]), HPV-39 (0.17 [0.09, 0.30]), HPV-59 (0.17 [0.09, 0.31]), HPV-73 (0.16 [0.06, 0.41]), and HPV-52 (0.16 [0.11, 0.23]). Conclusions Our results support the markedly higher oncogenic potentials of HPV-16 and -18, followed by HPV-31, -33, -39, -45, -52, -58 and -59, and highlight the need for further investigation of HPV-34, -67, -69 and -73. Overall, these findings could have important implications for the prevention of cervical cancer. PMID:23941096

  14. Comparing probabilistic and descriptive analyses of time-dose-toxicity relationship for determining no-observed-adverse-effect level in drug development.

    PubMed

    Glatard, Anaïs; Berges, Aliénor; Sahota, Tarjinder; Ambery, Claire; Osborne, Jan; Smith, Randall; Hénin, Emilie; Chen, Chao

    2015-10-15

    The no-observed-adverse-effect level (NOAEL) of a drug defined from animal studies is important for inferring a maximal safe dose in human. However, several issues are associated with its concept, determination and application. It is confined to the actual doses used in the study; becomes lower with increasing sample size or dose levels; and reflects the risk level seen in the experiment rather than what may be relevant for human. We explored a pharmacometric approach in an attempt to address these issues. We first used simulation to examine the behaviour of the NOAEL values as determined by current common practice; and then fitted the probability of toxicity as a function of treatment duration and dose to data collected from all applicable toxicology studies of a test compound. Our investigation was in the context of an irreversible toxicity that is detected at the end of the study. Simulations illustrated NOAEL's dependency on experimental factors such as dose and sample size, as well as the underlying uncertainty. Modelling the probability as a continuous function of treatment duration and dose simultaneously to data from multiple studies allowed the estimation of the dose, along with its confidence interval, for a maximal risk level that might be deemed as acceptable for human. The model-based data integration also reconciled between-study inconsistency and explicitly provided maximised estimation confidence. Such alternative NOAEL determination method should be explored for its more efficient data use, more quantifiable insight to toxic doses, and the potential for more relevant animal-to-human translation.

  15. How revascularization on the beating heart with cardiopulmonary bypass compares to off-pump? A meta-analysis of observational studies.

    PubMed

    Sepehripour, Amir H; Chaudhry, Umar A; Suliman, Amna; Kidher, Emaddin; Sayani, Nusrat; Ashrafian, Hutan; Harling, Leanne; Athanasiou, Thanos

    2016-01-01

    Off-pump coronary artery bypass surgery has been a controversial area of debate and the outcome profile of the technique has been thoroughly investigated. Scepticism regarding the reported outcomes and the conduct of the randomized trials comparing this technique with conventional on-pump coronary artery bypass surgery has been widely voiced, and the technique of off-pump surgery remains as an infrequently adopted approach to myocardial revascularization worldwide. Criticisms of the technique are related to lower rates of complete revascularization and its unknown long-term consequences, the significant detrimental effects on mortality and major adverse events when emergency conversion is required, and the significant lack of long-term survival and morbidity data. The hybrid technique of myocardial revascularization on the beating heart with the use of cardiopulmonary bypass may theoretically provide the beneficial effects of off-pump surgery in terms of myocardial protection and organ protection, while providing the safety and stability of on-pump surgery to allow complete revascularization. Large randomized comparison to support evidence-based choices is currently lacking. In this article, we have meta-analysed the outcomes of on-pump beating heart surgery in comparison with off-pump surgery focusing on major adverse cardiovascular and cerebrovascular adverse events (MACCE) including mortality, stroke and myocardial infarction and the degree of revascularization and number of bypass grafts performed. It was demonstrated that the beating heart on-pump technique allows a significantly higher number of bypass grafts to be performed, resulting in significantly higher degree of revascularization. We have also demonstrated a slightly higher rate of 30-day mortality and MACCE with the technique although not at a statistically significant level. These results should be considered alongside the population risk profile, where a significantly higher risk cohort had

  16. Evaluation of postextraction bleeding incidence to compare patients receiving and not receiving warfarin therapy: a cross-sectional, multicentre, observational study

    PubMed Central

    Iwabuchi, Hiroshi; Imai, Yutaka; Asanami, Soichiro; Shirakawa, Masayori; Yamane, Gen-yuki; Ogiuchi, Hideki; Kurashina, Kenji; Miyata, Masaru; Nakao, Hiroyuki; Imai, Hirohisa

    2014-01-01

    Objectives We investigated incidence and risk factors for postextraction bleeding in patients receiving warfarin and those not receiving anticoagulation therapy. Design Cross-sectional, multicentre, observational study. Setting 26 hospitals where an oral surgeon is available. Participants Data on 2817 teeth (from 496 patients receiving warfarin, 2321 patients not receiving warfarin; mean age (SD): 62.2 (17.6)) extracted between 1 November 2008 and 31 March 2010, were collected. Warfarin-receiving patients were eligible when prothrombin time–international normalised ratio (PT-INR) measured within 7 days prior to the extraction was less than 3.0. Interventions Simple dental extraction was performed, and incidence of postextraction bleeding and comorbidities were recorded. Primary and secondary outcome measures Postextraction bleeding not controlled by basic haemostasis procedure was clinically significant. Results Bleeding events were reported for 35 (7.1%) and 49 (2.1%) teeth, of which 18 (3.6%) and 9 (0.4%) teeth were considered clinically significant, in warfarin and non-warfarin groups, respectively, the difference between which was 3.24% (CI 1.58% to 4.90%). The incidence rates by patients were 2.77% and 0.39%, in warfarin and non-warfarin groups, respectively (incidence difference 2.38%, CI 0.65% to 4/10%). Univariate analyses showed that age (OR 0.197, p=0.001), PT-INR (OR 3.635, p=0.003), mandibular foramen conduction anaesthesia (OR 4.854, p=0.050) and formation of abnormal granulation tissue in extraction socket (OR 2.900, p=0.031) significantly correlate with bleeding incidence. Multivariate analysis revealed that age (OR 0.126, p=0.001), antiplatelet drugs (OR 0.100, p=0.049), PT-INR (OR 7.797, p=0.001) and history of acute inflammation at extraction site (OR 3.722, p=0.037) were significant risk factors for postextraction bleeding. Conclusions Our results suggest that there is slight but significant increase in the incidences of postextraction

  17. Comparative impact of antiretroviral drugs on markers of inflammation and immune activation during the first two years of effective therapy for HIV-1 infection: an observational study

    PubMed Central

    2014-01-01

    Background Few studies have compared the impact of different antiretroviral regimens on residual immune activation and inflammation with discordant results. Aim of the study was to investigate the impact of various antiretroviral regimens on markers of immune activation and inflammation during the first two years of effective therapy. Methods We studied HIV-infected antiretroviral-naïve patients who began cART with either abacavir/lamivudine or tenofovir/emtricitabine, combined with ritonavir-boosted lopinavir (LPV/r), atazanavir (ATV/r) or efavirenz (EFV). All the patients had a virological response within 6 months, which was maintained for 2 years with no change in their ART regimen. C-reactive protein (hs-CRP), interleukin-6 (IL-6), soluble CD14 (sCD14), monokine induced by interferon-γ (MIG) and interferon-γ-inducible protein-10 (IP-10) were measured in stored plasma obtained at cART initiation and 24 months later. Mean changes from baseline were analyzed on loge-transformed values and multivariable linear regression models were used to study the effect of the treatment components, after adjusting for factors that might have influenced the choice of ART regimen or biomarker levels. Differences were expressed as the mean fold change percentage difference (Δ). Results Seventy-eight patients (91% males) with a median age of 43 years met the inclusion criteria. Their median baseline CD4 cell count was 315/mm3 and HIV-1 RNA level 4.6 log10 copies/ml. During the 2-years study period, IL-6, IP-10 and MIG levels fell significantly, while hs-CRP and sCD14 levels remained stable. IP-10 and MIG levels declined significantly less strongly with ATV/r than with EFV (IP-10Δ -57%, p = 0.011; MIGΔ -136%, p = 0.007), while no difference was noted between LPV/r and EFV. The decline in IL-6 did not differ significantly across the different treatment components. Conclusions After the first 2 years of successful cART, IL-6, IP-10 and MIG fell markedly while hs

  18. Large-scale processes relevant to extreme hot and dry summer conditions in the South Central U.S.: Comparing observations with CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Ryu, J. H.; Hayhoe, K.

    2015-12-01

    In recent years, record high temperatures combined with extreme precipitation deficits have led to record-breaking droughts that have affected the Southern Plains. The 2011 drought and heat wave caused over $12B in damages across the SP region. Here, we combine station data with reanalysis to identify the hottest summers in the last 30 years. Consistent with previous analysis, we find that very hot temperatures over the region are highly correlated both precipitation as well as soil moisture deficits. Atmospheric circulation in the SP region during summer is generally dominated by the North Atlantic Subtropical High (NASH), which extends westward from its winter position over the Atlantic. The anticyclonic circulation could play a role in reducing convective precipitation as well as preventing disturbances from moving into the SP region. Examining the NARR reanalysis for the hottest summers of record, we find that the anticyclonic circulation associated with the NASH extends over the SP region relatively earlier in the summer and results in a comparatively stronger anticyclonic circulation, which in turn seems to be influenced by the large-scale climate variability. Specifically, the negative phase of the Pacific/North American (PNA) teleconnection pattern is characterized by high pressure anomalies across the southeastern and south central U.S. during summer. The two hottest years in the last three decades (1980 and 2011) also correlate with the two strongest negative PNA phases over that time. One of the anticipated impacts of human-induced climate change is the increased risk of hot and potentially dry summers across the SP region. For that reason, we also assess to what extent CMIP5 models are able simulate the large-scale processes that, according to reanalysis, are closely related to extreme hot and dry summer conditions over the Southern Plains. Composite maps of extreme heat years simulated in the models do display a stronger-than-average anticyclonic

  19. Comparative ionospheres

    NASA Astrophysics Data System (ADS)

    Cravens, T.

    2003-04-01

    Ionospheres are created as a consequence of the ionization of the neutral atoms and molecules in a planet’s upper atmosphere either by solar radiation or by fast charged particles. Ionospheres have been detected at all the planets except for Mercury and Pluto, either remotely or by in situ instruments. Active comets have ionospheres as do many planetary satellites, including Io, Europa, Ganymede, Titan, and Triton. A comparative review of ionospheres throughout the solar system will be given in this paper. Observations and theoretical models will be included in the review.

  20. Comparative hemorheology.

    PubMed

    Baskurt, Oguz K; Meiselman, Herbert J

    2013-01-01

    Comparative data on blood composition and blood flow properties indicate different levels of interspecies variation for several parameters. Hematocrit and hemoglobin levels have relatively low variability among mammals, while mean cell volume and red blood cell (RBC) count are more variable. There is also a difference of variability between high and low shear rate blood viscosity in mammals, with low shear rate viscosity having a higher degree of interspecies variation. This observation parallels the diversity of RBC aggregation among mammalian species. Allometric relations for blood rheology parameters indicate highly significant correlations of low shear rate blood viscosity and RBC aggregation with body weight, especially if species belonging to the order Artiodactyla are excluded. These allometric relations can be used to formulate various hypotheses about the evolutionary histories of circulatory functions, as well as hypotheses related to the role of RBC aggregation in the mammalian circulatory system. Such comparative studies and analytical reasoning based on comparative data may contribute to answering the "why" questions, and accordingly may improve our understanding of circulatory functions and hence may have possible clinical importance. During the last several decades, similar approaches to various medical concepts have yielded a new approach to medicine that is now known as Evolutionary Medicine.

  1. Multidetector computed tomography analysis of benign and malignant nodules in patients with chronic lymphocytic thyroiditis.

    PubMed

    Zhu, Caisong; Liu, Wei; Yang, Jun; Yang, Jing; Shao, Kangwei; Yuan, Lixin; Chen, Hairong; Lu, Wei; Zhu, Ying

    2016-07-01

    The aim of the present study was to compare the multidetector computed tomography (MDCT) features of benign and malignant nodules in patients with chronic lymphocytic thyroiditis (CLT). MDCT findings, including the size, solid percentage, calcification, margin, capsule, anteroposterior-transverse diameter ratio as well as the mode and the degree of enhancement of 137 thyroid nodules in 127 CLT cases were retrospectively analyzed. Furthermore, the correlation between MDCT findings and pathological results combined with the CT perfusion imaging was analyzed for the differences between benign and malignant nodules. A total of 77.5% (31/40) of malignant nodules were completely solid, and 33% (32/97) of benign nodules were predominantly cystic. Compared with the benign nodules, micro-calcification and internal calcification were more frequently observed in the malignant nodules (P<0.05). MDCT features such as ill-defined margin, absence of capsule or incomplete capsule or homogeneous enhancement were more likely to be present in the malignant nodules (P<0.05). Nevertheless, no significant difference was observed in the enhancement degree at arterial or venous phase between benign and malignant nodules (P>0.05). MDCT features are useful in differentiating the benign and malignant nodules in CLT patients, and it may be essential for a radiologist to review the MDCT characteristics of nodules in the clinical practice.

  2. Quantitative planar and volumetric cardiac measurements using 64 MDCT and 3T MRI versus standard 2D and M-mode echocardiography: Does anesthetic protocol matter?

    PubMed Central

    Drees, Randi; Johnson, Rebecca A; Stepien, Rebecca L; Rio, Alejandro Munoz Del; Saunders, Jimmy H; François, Christopher J

    2016-01-01

    Cross-sectional imaging of the heart utilizing computed tomography (CT) and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P=1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs. PMID:26082285

  3. Modifications in Lipid Levels Are Independent of Serum TNF-α in Rheumatoid Arthritis: Results of an Observational 24-Week Cohort Study Comparing Patients Receiving Etanercept Plus Methotrexate or Methotrexate as Monotherapy

    PubMed Central

    Rodriguez-Jimenez, Norma Alejandra; Garcia-Gonzalez, Carlos E.; Ayala-Lopez, Karina Patricia; Trujillo-Hernandez, Benjamin; Aguilar-Chavez, Erika Anita; Rocha-Muñoz, Alberto Daniel; Vasquez-Jimenez, Jose Clemente; Olivas-Flores, Eva; Salazar-Paramo, Mario; Corona-Sanchez, Esther Guadalupe; Vazquez-Del Mercado, Monica; Varon-Villalpando, Evangelina; Cota-Sanchez, Adolfo; Cardona-Muñoz, Ernesto German; Gamez-Nava, Jorge I.; Gonzalez-Lopez, Laura

    2014-01-01

    Objective. To compare the modifications in lipids between patients with rheumatoid arthritis (RA) receiving etanercept plus methotrexate (ETA + MTX) versus methotrexate (MTX) and their relationship with serum levels of tumor necrosis factor-alpha (TNF-α). Methods. In an observational cohort study, we compared changes in lipid levels in patients receiving ETA + MTX versus MTX in RA. These groups were assessed at baseline and at 4 and 24 weeks, measuring clinical outcomes, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, and TNF-α. Results. Baseline values for lipid levels were similar in both groups. HDL-C levels increased significantly only in the ETA + MTX group (from 45.5 to 50.0 mg/dL at 4 weeks, a 10.2% increase, P < 0.001, and to 56.0 mg/dL at 24 weeks, a 25.1% increase, P < 0.001), while other lipids underwent no significant changes. ETA + MTX also exhibited a significant increase in TNF-α (44.8 pg/mL at baseline versus 281.4 pg/mL at 24 weeks, P < 0.001). The MTX group had no significant changes in lipids or TNF-α. Significant differences in HDL-C between groups were observed at 24 weeks (P = 0.04) and also in TNF-α  (P = 0.01). Conclusion. HDL-C levels increased significantly following treatment with ETA + MTX, without a relationship with decrease of TNF-α. PMID:25243145

  4. Comparing Dark Energy Survey and HST –CLASH observations of the galaxy cluster RXC J2248.7–4431: Implications for stellar mass versus dark matter

    SciTech Connect

    Palmese, A.; Lahav, O.; Banerji, M.; Gruen, D.; Jouvel, S.; Melchior, P.; Aleksić, J.; Annis, J.; Diehl, H. T.; Hartley, W. G.; Jeltema, T.; Romer, A. K.; Rozo, E.; Rykoff, E. S.; Seitz, S.; Suchyta, E.; Zhang, Y.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Doel, P.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Li, T. S.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Miller, C. J.; Miquel, R.; Nord, B.; Ogando, R.; Plazas, A. A.; Roodman, A.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, D.; Vikram, V.

    2016-08-20

    We derive the stellar mass fraction in the galaxy cluster RXC J2248.7–4431 observed with the Dark Energy Survey (DES) during the Science Verification period. We compare the stellar mass results from DES (five filters) with those from the Hubble Space Telescope Cluster Lensing And Supernova Survey (CLASH; 17 filters). When the cluster spectroscopic redshift is assumed, we show that stellar masses from DES can be estimated within 25 per cent of CLASH values. We compute the stellar mass contribution coming from red and blue galaxies, and study the relation between stellar mass and the underlying dark matter using weak lensing studies with DES and CLASH. An analysis of the radial profiles of the DES total and stellar mass yields a stellar-to-total fraction of f* = (6.8 ± 1.7) × 10–3 within a radius of r200c ≃ 2 Mpc. Our analysis also includes a comparison of photometric redshifts and star/galaxy separation efficiency for both data sets. We conclude that space-based small field imaging can be used to calibrate the galaxy properties in DES for the much wider field of view. In conclusion, the technique developed to derive the stellar mass fraction in galaxy clusters can be applied to the ~100 000 clusters that will be observed within this survey and yield important information about galaxy evolution.

  5. Comparing Dark Energy Survey and HST –CLASH observations of the galaxy cluster RXC J2248.7-4431: implications for stellar mass versus dark matter

    SciTech Connect

    Palmese, A.; Lahav, O.; Banerji, M.; Gruen, D.; Jouvel, S.; Melchior, P.; Aleksić, J.; Annis, J.; Diehl, H. T.; Hartley, W. G.; Jeltema, T.; Romer, A. K.; Rozo, E.; Rykoff, E. S.; Seitz, S.; Suchyta, E.; Zhang, Y.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Doel, P.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Li, T. S.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Miller, C. J.; Miquel, R.; Nord, B.; Ogando, R.; Plazas, A. A.; Roodman, A.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, D.; Vikram, V.

    2016-08-20

    We derive the stellar mass fraction in the galaxy cluster RXC J2248.7-4431 observed with the Dark Energy Survey (DES) during the Science Verification period. We compare the stellar mass results from DES (5 filters) with those from the Hubble Space Telescope CLASH (17 filters). When the cluster spectroscopic redshift is assumed, we show that stellar masses from DES can be estimated within 25% of CLASH values. We compute the stellar mass contribution coming from red and blue galaxies, and study the relation between stellar mass and the underlying dark matter using weak lensing studies with DES and CLASH. An analysis of the radial profiles of the DES total and stellar mass yields a stellar-to-total fraction of f*=7.0+-2.2x10^-3 within a radius of r_200c~3 Mpc. Our analysis also includes a comparison of photometric redshifts and star/galaxy separation efficiency for both datasets. We conclude that space-based small field imaging can be used to calibrate the galaxy properties in DES for the much wider field of view. The technique developed to derive the stellar mass fraction in galaxy clusters can be applied to the ~100 000 clusters that will be observed within this survey. The stacking of all the DES clusters would reduce the errors on f* estimates and deduce important information about galaxy evolution.

  6. Efficacy and tolerability of an ectoine mouth and throat spray compared with those of saline lozenges in the treatment of acute pharyngitis and/or laryngitis: a prospective, controlled, observational clinical trial.

    PubMed

    Müller, Dörte; Lindemann, Torben; Shah-Hosseini, Kija; Scherner, Olaf; Knop, Markus; Bilstein, Andreas; Mösges, Ralph

    2016-09-01

    The aim of this observational trial was to evaluate the efficacy and tolerability of a mouth and throat spray containing ectoine in the treatment of acute pharyngitis and/or laryngitis. The outcome was compared with control treatment using saline lozenges. This study was designed as a prospective, controlled, non-randomized, observational multicenter clinical trial and was conducted in Germany. The study population consisted of 95 patients. The decision for treatment with either spray or lozenges was based on the patients' preference for pharyngeal or oral application. Investigators assessed symptoms specific to acute pharyngitis/laryngitis and determined the pharyngitis symptom score. Both patients and investigators evaluated the tolerability and efficacy of the treatment applied. Treatment with the spray showed higher efficacy, 1.95 ± 0.81 versus 1.68 ± 0.67 (investigators) and 1.97 ± 0.88 versus 1.57 ± 0.69 (patients, p < 0.05). Treatment with the spray resulted in significantly greater reduction of cervical lymph node swelling (p < 0.05), ∆ spray = 0.44 ± 0.62, ∆ lozenges = 0.21 ± 0.62. The lozenges showed some advantage in relieving cough, ∆ lozenges = 0.62 ± 0.94 versus ∆ spray = 0.44 ± 0.85. Both patients and investigators rated the tolerability of both medical devices as "good" to "very good". Adverse events of mild to moderate severity were either possibly related or not related to the medical devices used. No serious adverse events occurred. Taken together, while the tolerability was consistent in both treatment groups, the ectoine-based spray showed superior efficacy in treating acute pharyngitis and/or laryngitis.

  7. Eight-year observation and comparative study of specific pathogen-free cats experimentally infected with feline immunodeficiency virus (FIV) subtypes A and B: terminal acquired immunodeficiency syndrome in a cat infected with FIV petaluma strain.

    PubMed

    Kohmoto, M; Uetsuka, K; Ikeda, Y; Inoshima, Y; Shimojima, M; Sato, E; Inada, G; Toyosaki, T; Miyazawa, T; Doi, K; Mikami, T

    1998-03-01

    Three specific pathogen-free cats experimentally infected with feline immunodeficiency virus (FIV) strains Petaluma, TM1 and TM2, respectively were observed for over 8 years. Without showing any significant clinical signs of immunodeficiency syndrome (AIDS) for 8 years and 4 months of asymptomatic phase, the Petaluma-infected cat exhibited severe stomatitis/gingivitis, anorexia, emaciation, hematological and immunological disorders such as severe anemia, lymphopenia, thrombocytopenia, and decrease of CD4/CD8 ratio to 0.075, and finally died with hemoperitoneum at 8 years and 8 months post-infection. Histopathological studies revealed that the cat had systemic lymphoid atrophy and bone marrow disorders indicating acute myelocytic leukemia (aleukemic type). Plasma viral titer of the cat at AIDS phase was considerably high and anti-FIV antibody titer was slightly low as compared with the other FIV-infected cats. In addition, immunoblotting analysis using serially collected serum/plasma samples of these cats revealed that antibodies against FIV proteins were induced in all the infected cats, however in the Petaluma-infected cat anti-Gag antibodies disappeared during the asymptomatic period. These results suggested that plasma viral load and anti-FIV Gag antibody response correlated with disease progression, and supported FIV-infected cats as a suitable animal model of human AIDS.

  8. MDCT evaluation of sternal variations: Pictorial essay

    PubMed Central

    Duraikannu, Chary; Noronha, Olma V; Sundarrajan, Pushparajan

    2016-01-01

    Sternal variations and anomalies have been identified in the past during autopsy or cadaveric studies. Recently, an increasing number of minor sternal variations have been reported with the advent of multidetector computed tomography (CT). Although there are many sternal variations that occur with varying appearance and prevalence, most of them are not recognized or are underreported during routine imaging of thorax. Identification of sternal variations is important to differentiate from pathological conditions and to prevent fatal complications prior to sternal interventions like marrow aspiration or acupuncture. This article aims to describe the minor and asymptomatic sternal variations by multidetector CT and their clinical significance. PMID:27413263

  9. Bladder carcinoma: MDCT cystography and virtual cystoscopy.

    PubMed

    Panebianco, Valeria; Sciarra, Alessandro; Di Martino, Michele; Bernardo, Silvia; Vergari, Valeria; Gentilucci, Alessandro; Catalano, Carlo; Passariello, Roberto

    2010-06-01

    Bladder carcinoma is the most common tumor among the low urinary tract, accounting for 90% of cancer cases. Conventional cystoscopy represents the gold standard for diagnosis and local management of bladder carcinoma. As the prevalence of transitional cell carcinoma is four-fold greater in men than in women, the endoscopic procedure presents objective difficulties related to the length and bending of male urethra. The most important problems are represented by intense discomfort for the patient and bleeding; furthermore, the high cost, invasivity, and local complications such as infections and mechanical lesions are well-known drawbacks. Additionally, conventional cystoscopy does not provide information about extravescical extensions of the tumor. CT cystography, combined with virtual cystoscopy, is mandatory for TNM staging of the tumor and also is useful when conventional cystoscopy is inconclusive or cannot be performed. We presents the CT cystography findings with virtual endoscopy correlation and bladder carcinoma appearance.

  10. Cardiac Computed Tomography (Multidetector CT, or MDCT)

    MedlinePlus

    ... Graft (CABG) Surgery Atherosclerosis Coronary Artery Disease (CAD) Heart Attack • Home • About Heart Attacks • Warning Signs of a ... Heart Attack • Heart Attack Tools & Resources • Support Network Heart Attack Tools & Resources What Is a Heart Attack? How ...

  11. The Prostate Cancer Intervention Versus Observation Trial: VA/NCI/AHRQ Cooperative Studies Program #407 (PIVOT): design and baseline results of a randomized controlled trial comparing radical prostatectomy with watchful waiting for men with clinically localized prostate cancer.

    PubMed

    Wilt, Timothy J

    2012-12-01

    Prostate cancer is the most common noncutaneous malignancy and the second leading cause of cancer death in men. In the United States, 90% of men with prostate cancer are more than age 60 years, diagnosed by early detection with the prostate-specific antigen (PSA) blood test, and have disease believed confined to the prostate gland (clinically localized). Common treatments for clinically localized prostate cancer include watchful waiting (WW), surgery to remove the prostate gland (radical prostatectomy), external-beam radiation therapy and interstitial radiation therapy (brachytherapy), and androgen deprivation. Little is known about the relative effectiveness and harms of treatments because of the paucity of randomized controlled trials. The Department of Veterans Affairs/National Cancer Institute/Agency for Healthcare Research and Quality Cooperative Studies Program Study #407:Prostate Cancer Intervention Versus Observation Trial (PIVOT), initiated in 1994, is a multicenter randomized controlled trial comparing radical prostatectomy with WW in men with clinically localized prostate cancer. We describe the study rationale, design, recruitment methods, and baseline characteristics of PIVOT enrollees. We provide comparisons with eligible men declining enrollment and men participating in another recently reported randomized trial of radical prostatectomy vs WW conducted in Scandinavia. We screened 13 022 men with prostate cancer at 52 US medical centers for potential enrollment. From these, 5023 met initial age, comorbidity, and disease eligibility criteria, and a total of 731 men agreed to participate and were randomized. The mean age of enrollees was 67 years. Nearly one-third were African American. Approximately 85% reported that they were fully active. The median PSA was 7.8ng/mL (mean 10.2ng/mL). In three-fourths of men, the primary reason for biopsy leading to a diagnosis of prostate cancer was a PSA elevation or rise. Using previously developed tumor risk

  12. Comparing Composites.

    ERIC Educational Resources Information Center

    Mathras, Michael S.

    1993-01-01

    Presents an activity that models the work of chemical engineers. Students design, fabricate, and perform mechanical tests on plaster matrix composites and compare the strength to mass ratios of several products. (PR)

  13. Comparing Futures or Comparing Pasts?

    ERIC Educational Resources Information Center

    Cowen, Robert

    2000-01-01

    Comparative education should stop trying to figure out how to borrow educational systems from one culture and transplant them into another. Instead, it should focus on how educational systems can be described and explained, comparatively, in a way that captures the intersections of forces of history, social structures, and individuals' pedagogic…

  14. Left ventricular remodelling and systolic function measurement with 64 multi-slice computed tomography versus second harmonic echocardiography in patients with coronary artery disease: a double blind study.

    PubMed

    Palazzuoli, Alberto; Cademartiri, Filippo; Geleijnse, Marcel L; Meijboom, Bob; Pugliese, Francesca; Soliman, Osama; Calabrò, Anna; Nuti, Ranuccio; de Feyter, Pim

    2010-01-01

    The present study evaluated LV volumes, ejection fraction (LVEF) and stroke volume (SV) obtained by 64-MDCT and to compare these data with those obtained by second harmonic 2D Echo, in patients referred for non-invasive coronary vessels evaluation. The most common technique in daily clinical practice used for determination of LV function is two-dimensional echocardiography (2D-TTE). Multi-detector computed tomography (MDCT) is an emerging new technique to detect coronary artery disease (CAD) and was recently proposed to assess LV function. 93 patients underwent to 64-MDCT for LV function and volumes assessment by segmental reconstruction algorithm (Argus) and compared with recent (2 months) 2D-TTE, all images were processed and interpreted by two observers blinded to the Echo and MDCT results. A close correlation between TTE and 64 MDCT was demonstrated for the ejection fraction LVEF (r=0.84), end-diastolic volume LVEDV (r=0.80) and end-systolic volume LVESV (r=0.85); acceptable correlation was recruited for stroke volume LVSV (r=0.58). Optimal results were recruited for inter-observer variability for 64-MDCT measured in 45 patients: LVESV (r=0.82, p<0.001), LVEDV (r=0.83, p<0.001), LVEF (r=0.69, p<0.002) and SV (r=0.66, p<0.001). Our results, showed that functional and temporal information contained in a coronary 64-MDCT study can be used to assess left ventricular (LV) systolic function and LV dimensions with good reproducibility and acceptable correlation respect to 2D-TTE. The combination of non-invasive coronary artery imaging and assessment of global LV function might became in the future a fast and conclusive cardiac work-up in patients with CAD.

  15. Comparing Crystals

    ERIC Educational Resources Information Center

    Sharp, Janet; Hoiberg, Karen; Chumbley, Scott

    2003-01-01

    This standard lesson on identifying salt and sugar crystals expands into an opportunity for students to develop their observation, questioning, and modeling skills. Although sugar and salt may look similar, students discovered that they looked very different under a magnifying glass and behaved differently when dissolved in water. In addition,…

  16. Comparing Pluralities

    ERIC Educational Resources Information Center

    Scontras, Gregory; Graff, Peter; Goodman, Noah D.

    2012-01-01

    What does it mean to compare sets of objects along a scale, for example by saying "the men are taller than the women"? We explore comparison of pluralities in two experiments, eliciting comparison judgments while varying the properties of the members of each set. We find that a plurality is judged as "bigger" when the mean size of its members is…

  17. Comparative Analysis.

    DTIC Science & Technology

    1987-11-01

    Al" 56 COMPARATIVE ANALYSIS(U) MASSACJWSETTS INST OF TECH 1/1 CAMBRIDGE ARTIFICIAL INTELLIGENCE LAO 9 S MELD NOV B, RI-N-95i NMM4-85-K-0124...0 0 0 0 0 0 i. -~~ --- WU V1 2 fwx~, - - W-na alc F!LFI MASSACHUSETTS INSTITUTE OF TECHNOLOGY CO ARTIFICIAL INTELLIGENCE LABORATORY Lfl 0 Al/Memo...differential qualita- tive (DQ) analysis, which solves the task, providing explanations suitable for use by design systems, automated diagnosis, intelligent

  18. Comparative evaluations.

    PubMed

    Bibace, Roger

    2008-03-01

    My response to Engelmann (2008) will be based on several questions that will allow both its author and the general reader to determine whether the assumptions I make as an interpreter of this complex paper are congruent or incongruent with their own interpretations of the text. The interpretations by the writer, by any commentator, and the diverse interpretations of a general audience together with my own interpretations will, I hope, facilitate some fruitful 'comparative evaluations.' I articulate my inferences of the most dense part of the paper, namely the 'concrete immediate Consciousness and the developing absent outside.' My hope is to address Engelmann's question: "Am I in a better disposition to judge modern theories of consciousness?" The last section of my response spells out more personal comments to my all too brief and single encounter with Arno Engelmann. It is there that Arno Engelmann's fascinating statement "I am a citizen of the world" is addressed through its counterparts in my life.

  19. Computing by Observing Changes

    NASA Astrophysics Data System (ADS)

    Cavaliere, Matteo; Leupold, Peter

    Computing by Observing is a paradigm for the implementation of models of Natural Computing. It was inspired by the setup of experiments in biochemistry. One central feature is an observer that translates the evolution of an underlying observed system into sequences over a finite alphabet. We take a step toward more realistic observers by allowing them to notice only an occurring change in the observed system rather than to read the system's entire configuration. Compared to previous implementations of the Computing by Observing paradigm, this decreases the computational power; but with relatively simple systems we still obtain the language class generated by matrix grammars.

  20. Diagnostic capability of gadoxetate disodium-enhanced liver MRI for diagnosis of hepatocellular carcinoma: comparison with multi-detector CT.

    PubMed

    Toyota, Naoyuki; Nakamura, Yuko; Hieda, Masashi; Akiyama, Naoko; Terada, Hiroaki; Matsuura, Noriaki; Nishiki, Masayo; Kono, Hirotaka; Kohno, Hiroshi; Irei, Toshimitsu; Yoshikawa, Yukinobu; Kuraoka, Kazuya; Taniyama, Kiyomi; Awai, Kazuo

    2013-09-01

    The purpose of this study was to evaluate the diagnostic capability of gadoxetate disodium (Gd-EOB)-MRI for the detection of hepatocellular carcinoma (HCC) compared with multidetector CT (MDCT). Fifty patients with 57 surgically proven HCCs who underwent Gd-EOB-MRI and MDCT from March 2008 to June 2011 were evaluated. Two observers evaluated MR and CT on a lesion-by-lesion basis. We analyzed sensitivity by grading on a 5-point scale, the degree of arterial enhancement and the differences in histological grades in the diffusion-weighted images (DWI). The results showed that the sensitivity of Gd-EOB-MRI was higher than that of MDCT especially for HCCs that were 1 cm in diameter or smaller. The hepatobiliary phase was useful for the detecting of small HCC. We had few cases in which it was difficult to judge HCC in the arterial enhancement between MRI and MDCT. In the diffusion-weighted image, well differentiated HCC tended to show a low signal intensity, and poorly differentiated HCC tended to show a high signal intensity. In moderately differentiated HCC's, the mean diameter of the high signal intensity group was larger than that of the low signal intensity group (24.5 mm vs. 15.8 mm). In conclusion, Gd-EOB-MRI tended to show higher sensitivity compared to MDCT in the detection of HCC.

  1. A comparative study of Solar-Heliospheric Observations during very active Sun intervals in the 21st and 23rd solar cycles (April 1979 and March-April, 2001)

    NASA Astrophysics Data System (ADS)

    Berdichevsky, D. B.; Farrugia, C. J.; Lepping, R. P.; Richardson, I. G.; Galvin, A. B.; Schwenn, R.; Reames, D. V.

    2002-05-01

    On March 24, 2001, the largest sun spot group in 10 years, consisting of three or more active regions (ARs) centered near AR 9393, emerged from behind the eastern limb of the Sun and began a 2-week passage across the visible hemisphere. During the same time, the Sun showed several other ARs so this period constituted a phase of unusually intense solar activity that continued almost 18 days beyond the disk passage of the largest sun spot group and included possibly the most energetic solar flare event in modern records (a > X20 flare in soft X-rays). We shall present an overview of the associated solar energetic particle events and an analysis of the thermodynamic characteristics of the shocks observed in the Earth's vicinity. The investigation includes cross-correlation analysis of interplanetary plasma and magnetic field observations at ACE (SWEPAM/MAG level-2 data) situated 250 Re upstream of Earth and at Wind (SWE/MFI data), which was ahead of Earth and executing a distant prograde orbit with large Y-coordinate. The interval under study bears a close resemblance to a similar active period during April 1979 (i.e., 2 solar cycles earlier) observed by the Helios 1/2 probes and Earth solar wind monitors (ISEE-3, IMP). The similarities and differences between the two intervals are examined further.

  2. Skin Barrier Function Is Not Impaired and Kallikrein 7 Gene Polymorphism Is Frequently Observed in Korean X-linked Ichthyosis Patients Diagnosed by Fluorescence in Situ Hybridization and Array Comparative Genomic Hybridization.

    PubMed

    Lee, Noo Ri; Yoon, Na Young; Jung, Minyoung; Kim, Ji-Yun; Seo, Seong Jun; Wang, Hye-Young; Lee, Hyeyoung; Sohn, Young Bae; Choi, Eung Ho

    2016-08-01

    X-linked ichthyosis (XLI) is a recessively inherited ichthyosis. Skin barrier function of XLI patients reported in Western countries presented minimally abnormal or normal. Here, we evaluated the skin barrier properties and a skin barrier-related gene mutation in 16 Korean XLI patients who were diagnosed by fluorescence in situ hybridization and array comparative genomic hybridization analysis. Skin barrier properties were measured, cytokine expression levels in the stratum corneum (SC) were evaluated with the tape stripped specimen from skin surface, and a genetic test was done on blood. XLI patients showed significantly lower SC hydration, but normal basal trans-epidermal water loss and skin surface pH as compared to a healthy control group. Histopathology of ichthyosis epidermis showed no acanthosis, and levels of the pro-inflammatory cytokines in the corneal layer did not differ between control and lesional/non-lesional skin of XLI patients. Among the mutations in filaggrin (FLG), kallikrein 7 (KLK7), and SPINK5 genes, the prevalence of KLK7 gene mutations was significantly higher in XLI patients (50%) than in controls (0%), whereas FLG and SPINK5 prevalence was comparable. Korean XLI patients exhibited unimpaired skin barrier function and frequent association with the KLK7 gene polymorphism, which may differentiate them from Western XLI patients.

  3. Skin Barrier Function Is Not Impaired and Kallikrein 7 Gene Polymorphism Is Frequently Observed in Korean X-linked Ichthyosis Patients Diagnosed by Fluorescence in Situ Hybridization and Array Comparative Genomic Hybridization

    PubMed Central

    2016-01-01

    X-linked ichthyosis (XLI) is a recessively inherited ichthyosis. Skin barrier function of XLI patients reported in Western countries presented minimally abnormal or normal. Here, we evaluated the skin barrier properties and a skin barrier-related gene mutation in 16 Korean XLI patients who were diagnosed by fluorescence in situ hybridization and array comparative genomic hybridization analysis. Skin barrier properties were measured, cytokine expression levels in the stratum corneum (SC) were evaluated with the tape stripped specimen from skin surface, and a genetic test was done on blood. XLI patients showed significantly lower SC hydration, but normal basal trans-epidermal water loss and skin surface pH as compared to a healthy control group. Histopathology of ichthyosis epidermis showed no acanthosis, and levels of the pro-inflammatory cytokines in the corneal layer did not differ between control and lesional/non-lesional skin of XLI patients. Among the mutations in filaggrin (FLG), kallikrein 7 (KLK7), and SPINK5 genes, the prevalence of KLK7 gene mutations was significantly higher in XLI patients (50%) than in controls (0%), whereas FLG and SPINK5 prevalence was comparable. Korean XLI patients exhibited unimpaired skin barrier function and frequent association with the KLK7 gene polymorphism, which may differentiate them from Western XLI patients. PMID:27478344

  4. Whipple Observations

    NASA Astrophysics Data System (ADS)

    Trangsrud, A.

    2015-12-01

    The solar system that we know today was shaped dramatically by events in its dynamic formative years. These events left their signatures at the distant frontier of the solar system, in the small planetesimal relics that populate the vast Oort Cloud, the Scattered Disk, and the Kuiper Belt. To peer in to the history and evolution of our solar system, the Whipple mission will survey small bodies in the large volume that begins beyond the orbit of Neptune and extends out to thousands of AU. Whipple detects these objects when they occult distant stars. The distance and size of the occulting object is reconstructed from well-understood diffraction effects in the object's shadow. Whipple will observe tens of thousands of stars simultaneously with high observing efficiency, accumulating roughly a billion "star-hours" of observations over its mission life. Here we describe the Whipple observing strategy, including target selection and scheduling.

  5. Low-latitude gravity wave variances in the mesosphere and lower thermosphere derived from SABER temperature observation and compared with model simulation of waves generated by deep tropical convection

    NASA Astrophysics Data System (ADS)

    Walterscheid, R. L.; Christensen, A. B.

    2016-10-01

    A portion of waves generated by deep convection have scales and amplitudes large enough to be detected by spaceborne instruments. We have analyzed temperature data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite for subtidal-scale fluctuations. Filtering was applied both vertically and horizontally to extract wave variances. We have analyzed the altitude region between 70 and 130 km and focus on the variances at equatorial latitudes for the altitude region between 70 and 120 km as a function of season, local time intervals, geographical location, and altitude. We find significant variances where convection is particularly prolific (Intertropical Convergence Zone) and at altitudes where wave trapping is known to be favored (e.g., the lower thermospheric duct). The locations of significant variances persist from year to year. Standard deviations of a few tens of kelvins are found. We have also performed simulations of the response to deep tropical convection with a time-dependent, high-resolution fully compressible dynamical model. Our simulations give wave amplitudes that agree reasonably well with the observed amplitudes and show layering that is consistent with the observations. Our main finding is that significant variations seen in TIMED/SABER temperature data have a convective wave source and are concentrated in layers where thermal ducts occur.

  6. Flare Observations.

    PubMed

    Benz, Arnold O

    Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays at 100 MeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, and SOHO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections (CMEs), electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s) of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting reconnection of magnetic field lines as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth's lower ionosphere. While flare scenarios have slowly converged over the past decades, every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions.

  7. Comparing model predictions and experimental data for the response of stomatal conductance and guard cell turgor to manipulations of cuticular conductance, leaf-to-air vapour pressure difference and temperature: feedback mechanisms are able to account for all observations.

    PubMed

    Eamus, Derek; Taylor, Daniel T; Macinnis-Ng, Catriona M O; Shanahan, Steve; De Silva, Lionel

    2008-03-01

    Stomata respond to increasing leaf-to-air vapour pressure difference (LAVPD) (D) by closing. The mechanism by which this occurs is debated. A role for feedback and peristomatal transpiration has been proposed. In this paper, we apply a recent mechanistic model of stomatal behaviour, and compare model and experimental data for the influence of increasing D on stomatal conductance. We manipulated cuticular conductance (g(c)) by three independent methods. First, we increased g(c) by using a solvent mixture applied to both leaf surfaces prior to determining stomatal responses to D; second, we increased g(c) by increasing leaf temperature at constant D; and third, we coated a small area of leaf with a light oil to decrease g(c). In all three experiments, experimental data and model outputs showed very close agreement. We conclude, from the close agreement between model and experimental data and the fact that manipulations of g(c), and hence cuticular transpiration, influenced g(s) in ways consistent with a feedback mechanism, that feedback is central in determining stomatal responses to D.

  8. Muon Observations

    NASA Astrophysics Data System (ADS)

    Duldig, Marc L.

    2000-07-01

    Muon observations are complementary to neutron monitor observations but there are some important differences in the two techniques. Unlike neutron monitors, muon telescope systems use coincidence techniques to obtain directional information about the arriving particle. Neutron monitor observations require simple corrections for pressure variations to compensate for the varying mass of atmospheric absorber over a site. In contrast, muon observations require additional corrections for the positive and negative temperature effects. Muon observations commenced many years before neutron monitors were constructed. Thus, muon data over a larger number of solar cycles is available to study solar modulation on anisotropies and other cosmic ray variations. The solar diurnal and semi-diurnal variations have been studied for many years. Using the techniques of Bieber and Chen it has been possible to derive the radial gradient, parallel mean-free path and symmetric latitude gradient of cosmic rays for rigidities <200 GV. The radial gradient varies with the 11-year solar activity cycle whereas the parallel mean-free path appears to vary with the 22-year solar magnetic cycle. The symmetric latitudinal gradient reverses at each solar polarity reversal. These results are in general agreement with predictions from modulation models. In undertaking these analyses the ratio of the parallel to perpendicular mean-free path must be assumed. There is strong contention in the literature about the correct value to employ but the results are sufficiently robust for this to be, at most, a minor problem. An asymmetric latitude gradient of highly variable nature has been found. These observations do not support current modulation models. Our view of the sidereal variation has undergone a revolution in recent times. Nagashima, Fujimoto and Jacklyn proposed a narrow Tail-In source anisotropy and separate Loss-Cone anisotropy as being responsible for the observed variations. A new analysis

  9. Shallow-source aeromagnetic anomalies observed over the West Antarctic Ice Sheet compared with coincident bed topography from radar ice sounding—new evidence for glacial "removal" of subglacially erupted late Cenozoic rift-related volcanic edifices

    NASA Astrophysics Data System (ADS)

    Behrendt, John C.; Blankenship, Donald D.; Morse, David L.; Bell, Robin E.

    2004-07-01

    Aeromagnetic and radar ice sounding results from the 1991-1997 Central West Antarctica (CWA) aerogeophysical survey over part of the West Antarctic Ice Sheet (WAIS) and subglacial area of the volcanically active West Antarctic rift system have enabled detailed examination of specific anomaly sources. These anomalies, previously interpreted as caused by late Cenozoic subglacial volcanic centers, are compared to newly available glacial bed-elevation data from the radar ice sounding compilation of the entire area of the aeromagnetic survey to test this hypothesis in detail. We examined about 1000 shallow-source magnetic anomalies for bedrock topographic expression. Using very conservative criteria, we found over 400 specific anomalies which correlate with bed topography directly beneath each anomaly. We interpret these anomalies as indicative of the relative abundance of volcanic anomalies having shallow magnetic sources. Of course, deeper source magnetic anomalies are present, but these have longer wavelengths, lower gradients and mostly lower amplitudes from those caused by the highly magnetic late Cenozoic volcanic centers. The great bulk of these >400 (40-1200-nT) anomaly sources at the base of the ice have low bed relief (60-600 m, with about 80%<200 m). We interpret this relief as an indication of residual topography after glacial removal of volcanic edifices comprising hyaloclastite, pillow breccia and other volcanic debris erupted into the moving ice during volcanism since the initiation of the WAIS >10 million years ago. Eighteen of the anomalies examined, about half concentrated in the area of the WAIS divide, have high-topographic expression (as great as 400 m above sea level) and high bed relief (up to 1500 m). All of these high-topography anomaly sources at the base of the ice would isostatically rebound to elevations above sea level were the ice removed. We interpret these 18 anomaly sources as evidence of subaerial eruption of volcanoes whose topography

  10. Shallow-source aeromagnetic anomalies observed over the West Antarctic Ice Sheet compared with coincident bed topography from radar ice sounding - New evidence for glacial "removal" of subglacially erupted late Cenozoic rift-related volcanic edifices

    USGS Publications Warehouse

    Behrendt, John C.; Blankenship, D.D.; Morse, D.L.; Bell, R.E.

    2004-01-01

    Aeromagnetic and radar ice sounding results from the 1991-1997 Central West Antarctica (CWA) aerogeophysical survey over part of the West Antarctic Ice Sheet (WAIS) and subglacial area of the volcanically active West Antarctic rift system have enabled detailed examination of specific anomaly sources. These anomalies, previously interpreted as caused by late Cenozoic subglacial volcanic centers, are compared to newly available glacial bed-elevation data from the radar ice sounding compilation of the entire area of the aeromagnetic survey to test this hypothesis in detail. We examined about 1000 shallow-source magnetic anomalies for bedrock topographic expression. Using very conservative criteria, we found over 400 specific anomalies which correlate with bed topography directly beneath each anomaly. We interpret these anomalies as indicative of the relative abundance of volcanic anomalies having shallow magnetic sources. Of course, deeper source magnetic anomalies are present, but these have longer wavelengths, lower gradients and mostly lower amplitudes from those caused by the highly magnetic late Cenozoic volcanic centers. The great bulk of these >400 (40-1200-nT) anomaly sources at the base of the ice have low bed relief (60-600 m, with about 80%10 million years ago. Eighteen of the anomalies examined, about half concentrated in the area of the WAIS divide, have high-topographic expression (as great as 400 m above sea level) and high bed relief (up to 1500 m). All of these high-topography anomaly sources at the base of the ice would isostatically rebound to elevations above sea level were the ice removed. We interpret these 18 anomaly sources as evidence of subaerial eruption of volcanoes whose topography was protected from erosion by competent volcanic flows similar to prominent volcanic peaks that are exposed above the surface of the WAIS. Further, we infer these volcanoes as possibly erupted at a time when the WAIS was absent. In contrast, at the other extreme

  11. Observational astrophysics.

    NASA Astrophysics Data System (ADS)

    Léna, P.; Lebrun, F.; Mignard, F.

    This book is the 2nd edition of an English translation published in 1988 (45.003.105) of the French original "Astrophysique: Méthodes physiques de l'observation" published in 1986 (42.003.048). Written specifically for physicists and graduate students in astronomy, this textbook focuses on astronomical observation and on the basic physical principles that astronomers use to conceive, build and exploit their instruments at their ultimate limits in sensitivity or resolution. This second edition has been entirely restructured and almost doubled in size, in order to improve its clarity and to account for the great progress achieved in the last 15 years. It deals with ground-based and space-based astronomy and their respective fields. It presents the new generation of giant ground-based telescopes, with the new methods of optical interferometry and adaptive optics, and also the ambitious concepts behind planned space missions for the next decades. Avoiding particulars, it covers the whole of the electromagnetic spectrum and touches upon the "new astronomies" becoming possible with gravitational waves and neutrinos.

  12. ASCA Observations

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1998-01-01

    This recently expired grant has supported the work of the PI, his students, and his collaborators on a variety of ASCA projects over the past four years. Annual reports have summarized much of the work accomplished; here we provide a brief review of the work resulting from this effort, and a summary of the personnel who have benefited from the grant's support. Starburst Galaxies with Extreme X-ray Luminosities This project began as a careful examination of the claims of Boller et al. (1992) that there were dozens of "normal" galaxies in the ROSAT All-Sky Survey that had X-ray luminosities in excess of 1042 erg sec, higher than that seen in the hundreds of non-AGN galaxies observed with Einstein. If true, this suggested that X-ray emission associated with star formation activity might have a significant contribution to make to the still unexplained cosmic X-ray background (XRB). Since some of our earlier work with the Einstein Observatory Deep Surveys had suggested a similar possibility and several sets of authors over the years had modelled the starburst XRB contribution, these claims were worth pursuing. Our work expanded the examination beyond the RASS to include earlier claims of high-luminosity galaxies powered by starburst emission (selected in this case on the basis of the far-IR luminosities). The result of extensive followup observations under several programs using ROSAT, ASCA, and ground-based facilities was to show that nearly all of these objects in fact have hidden AGN at their cores, and that their luminosities are not in any way extraordinary.

  13. Observations of FK Comae stars

    NASA Technical Reports Server (NTRS)

    Bopp, B. W.

    1981-01-01

    Observations on the FK Comae stars are described. FK Com, UZ Lib and HD 199178 are compared and related as a group of stars. The crucial observational tests of the proposed evolutionary status of these stars are noted.

  14. Energetics of a Global Ocean Circulation Model Compared to Observations

    DTIC Science & Technology

    2011-08-09

    in the dynamics of the ocean circulation with instabilities of the strong mean currents generating eddies in the upper ocean. Interactions between...obser- vations from surface drifters, geostrophic currents from satellite altimetry, subsurface floats and deep current meter moorings. HYCOM...rings of the boundary currents [Stammer, 1997; Ferrari and Wunsch, 2009, 2010], is generated by instabilities of the mean flow and direct wind forcing

  15. Observational exobiology

    NASA Technical Reports Server (NTRS)

    Tarter, J.

    1986-01-01

    The Earth's atmosphere absorbs partially or completely many ultraviolet, infrared and submillimeter wavelengths. Atmospheric seeing distorts small images, imposing a limit on the achievable angular resolution at optical and infrared wavelengths that is much poorer than the intrinsic capability of telescope optics. The atomic and molecular species of the atmosphere confuse or prevent the spectral studies of similar compounds outside of the terrestrial environment. Telescopes placed in orbit above the atmosphere avoid these problems and enjoy a unique view of the universe. There are many complex questions pertaining to the origin and evolution of the biogenic elements and compounds and the existence of terrestrial types of planets elsewhere that can be only tackled from orbiting facilities. The detailed nature of the spacecraft, platforms and instrumentation most likely to be launched by the United States and Europe in the near future in an attempt to determine what observational programs would be tractable and which areas of interest to exobiology required hardware capabilities beyond those currently envisioned are considered.

  16. Detection of root perforations using conventional and digital intraoral radiography, multidetector computed tomography and cone beam computed tomography

    PubMed Central

    Eskandarloo, Amir; Noruzi-Gangachin, Maruf; Khajeh, Samira

    2015-01-01

    Objectives This study aimed to compare the accuracy of conventional intraoral (CI) radiography, photostimulable phosphor (PSP) radiography, cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) for detection of strip and root perforations in endodontically treated teeth. Materials and Methods Mesial and distal roots of 72 recently extracted molar were endodontically prepared. Perforations were created in 0.2, 0.3, or 0.4 mm diameter around the furcation of 48 roots (strip perforation) and at the external surface of 48 roots (root perforation); 48 roots were not perforated (control group). After root obturation, intraoral radiography, CBCT and MDCT were taken. Discontinuity in the root structure was interpreted as perforation. Two observers examined the images. Data were analyzed using Stata software and Chi-square test. Results The sensitivity and specificity of CI, PSP, CBCT and MDCT in detection of strip perforations were 81.25% and 93.75%, 85.42% and 91.67%, 97.92% and 85.42%, and 72.92% and 87.50%, respectively. For diagnosis of root perforation, the sensitivity and specificity were 87.50% and 93.75%, 89.58% and 91.67%, 97.92% and 85.42%, and 81.25% and 87.50%, respectively. For detection of strip perforation, the difference between CBCT and all other methods including CI, PSP and MDCT was significant (p < 0.05). For detection of root perforation, only the difference between CBCT and MDCT was significant, and for all the other methods no statistically significant difference was observed. Conclusions If it is not possible to diagnose the root perforations by periapical radiographs, CBCT is the best radiographic technique while MDCT is not recommended. PMID:25671214

  17. Observations of Umbral Flashes

    NASA Astrophysics Data System (ADS)

    Rouppe van der Voort, L. H. M.; Krijger, J. M.

    2003-10-01

    We present observations of oscillations in the chromosphere of the umbra of sunspots. The observations were obtained with the Swedish Vacuum Solar Telescope (SVST) and the Dutch Open Telescope (DOT) on La Palma, comprising spectrograms and filtergrams in the Ca II H line. The sawtooth pattern in the spectroscopic time evolution of the Ca II H core is shown as well as evidence for a connection between umbral flashes and running penumbral waves from image sequences. Running waves, coherent over a large fraction of the penumbra, seem to be excited by flashes that occur close to the umbra-penumbral boundary. Comparing the intensity oscillations in the Ca II H line with TRACE observations in the 1600 Å passband, we find a phase difference of approximately 25 ° with 1600 Å leading the Ca II H intensity oscillation which we attribute to complex dynamical behaviour.

  18. Observation of WZ production.

    PubMed

    Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arguin, J-F; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Bedeschi, F; Behari, S; Belforte, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Budroni, S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciljak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenaro, C; Cuevas, J; Culbertson, R; Cully, J C; Cyr, D; DaRonco, S; Datta, M; D'Auria, S; Davies, T; D'Onofrio, M; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdeckerc, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; DiTuro, P; Dörr, C; Donati, S; Donega, M; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Griffiths, M; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ishizawa, Y; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jensen, H; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kovalev, A; Kraan, A C; Kraus, J; Kravchenko, I; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Manca, G; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McCarthy, K; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Nachtman, J; Nagano, A; Naganoma, J; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nigmanov, T; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ranjan, N; Rappoccio, S; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Sabik, S; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Saltzberg, D; Sánchez, C; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojma, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Sjolin, J; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuchiya, R; Tsuno, S; Turini, N; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vallecorsa, S; Vanguri, R; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Veramendi, G; Veszpremi, V; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waschke, S; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2007-04-20

    We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1 fb;-1 of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7+/-0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to 6 standard deviations. The measured cross section is sigma(pp-->WZ)=5.0(-1.6)(+1.8) pb, consistent with the standard model expectation.

  19. Awareness as observational heterarchy

    PubMed Central

    Sonoda, Kohei; Kodama, Kentaro; Gunji, Yukio-Pegio

    2013-01-01

    Libet et al. (1983) revealed that brain activity precedes conscious intention. For convenience in this study, we divide brain activity into two parts: a conscious field (CF) and an unconscious field (UF). Most studies have assumed a comparator mechanism or an illusion of CF and discuss the difference of prediction and postdiction. We propose that problems to be discussed here are a twisted sense of agency between CF and UF, and another definitions of prediction and postdiction in a mediation process for the twist. This study specifically examines the definitions throughout an observational heterarchy model based on internal measurement. The nature of agency must be emergence that involves observational heterarchy. Consequently, awareness involves processes having duality in the sense that it is always open to the world (postdiction) and that it also maintains self robustly (prediction). PMID:24101912

  20. COMPTEL solar flare observations

    NASA Technical Reports Server (NTRS)

    Ryan, J. M.; Aarts, H.; Bennett, K.; Debrunner, H.; Devries, C.; Denherder, J. W.; Eymann, G.; Forrest, D. J.; Diehl, R.; Hermsen, W.

    1992-01-01

    COMPTEL as part of a solar target of opportunity campaign observed the sun during the period of high solar activity from 7-15 Jun. 1991. Major flares were observed on 9 and 11 Jun. Although both flares were large GOES events (greater than or = X10), they were not extraordinary in terms of gamma-ray emission. Only the decay phase of the 15 Jun. flare was observed by COMPTEL. We report the preliminary analysis of data from these flares, including the first spectroscopic measurement of solar flare neutrons. The deuterium formation line at 2.223 MeV was present in both events and for at least the 9 Jun. event, was comparable to the flux in the nuclear line region of 4-8 MeV, consistent with Solar-Maximum Mission (SSM) Observations. A clear neutron signal was present in the flare of 9 Jun. with the spectrum extending up to 80 MeV and consistent in time with the emission of gamma-rays, confirming the utility of COMPTEL in measuring the solar neutron flux at low energies. The neutron flux below 100 MeV appears to be lower than that of the 3 Jun. 1982 flare by more than an order of magnitude. The neutron signal of the 11 Jun. event is under study. Severe dead time effects resulting from the intense thermal x-rays require significant corrections to the measured flux which increase the magnitude of the associated systematic uncertainties.

  1. Observing with the Armillary Astrolabe

    NASA Astrophysics Data System (ADS)

    Wlodarczyk, J.

    1987-08-01

    The author investigates the merits and limitations of the armillary astrolabe, which served for direct observations of the ecliptic longitudes and latitudes of the heavenly bodies from Antiquity to the end of the sixteenth century. Observations made with a modern replica of the instrument are compared with historical astrolabic observations as reported by Ptolemy in the Almagest and with measurements made in 1503-4 by Bernard Walther in Nuremberg.

  2. Understanding Comparability of Examination Standards

    ERIC Educational Resources Information Center

    Coe, Robert

    2010-01-01

    Much of the argument about comparability of examination standards is at cross-purposes; contradictory positions are in fact often both defensible, but they are using the same words to mean different things. To clarify this, two broad conceptualisations of standards can be identified. One sees the standard in the observed phenomena of performance…

  3. Observations to information

    NASA Astrophysics Data System (ADS)

    Cox, S. J.

    2013-12-01

    . Communities generating data using ships, satellites and aircraft habitually classify observations by the source platform and mission, as this implies a rich set of metadata to the cognoscenti. However, integrators are more likely to focus on the phenomenon being observed, together with the location of the features carrying it. In this context sensor information informs quality evaluation, as a secondary consideration following after data discovery. The observation model is specialized by constraining facets, such as observed property, sensor or procedure, to be taken from a specific set or vocabulary. Such vocabularies are typically developed on a project or community basis, but data fusion depends on them being widely accessible, and comparable with related vocabularies. Better still if they are transparently governed, trusted and stable enough to encourage re-use. Semantic web technologies support distribution of rigorously constructed vocabularies through standard interfaces, with standard mechanisms for asserting or inferring of proximity and other relationships. Interoperability of observation data in future is likely to depend on the development of a viable ecosystem of these secondary resources.

  4. Comparing Mutational Variabilities

    PubMed Central

    Houle, D.; Morikawa, B.; Lynch, M.

    1996-01-01

    We have reviewed the available data on V(M), the amount of genetic variation in phenotypic traits produced each generation by mutation. We use these data to make several qualitative tests of the mutation-selection balance hypothesis for the maintenance of genetic variance (MSB). To compare V(M) values, we use three dimensionless quantities: mutational heritability, V(M)/V(E); the mutational coefficient of variation, CV(M); and the ratio of the standing genetic variance to V(M), V(G)/V(M). Since genetic coefficients of variation for life history traits are larger than those for morphological traits, we predict that under MSB, life history traits should also have larger CV(M). This is confirmed; life history traits have a median CV(M) value more than six times higher than that for morphological traits. V(G)/V(M) approximates the persistence time of mutations under MSB in an infinite population. In order for MSB to hold, V(G)/V(M) must be small, substantially less than 1000, and life history traits should have smaller values than morphological traits. V(G)/V(M) averages about 50 generations for life history traits and 100 generations for morphological traits. These observations are all consistent with the predictions of a mutation-selection balance model. PMID:8807316

  5. Satellite signatures in SLR observations

    NASA Technical Reports Server (NTRS)

    Appleby, G. M.

    1993-01-01

    We examine the evidence for the detection of satellite-dependent signatures in the laser range observations obtained by the UK single-photon Satellite Laser Ranging (SLR) System models of the expected observation distributions from Ajisai and Lageos are developed from the published satellite spread functions and from the characteristics of the SLR System and compared with the observations. The effects of varying return strengths are discussed using the models and by experimental observations of Ajisai, during which a range of return levels from single to multiple photons is achieved. The implications of these results for system-dependent center for mass corrections are discussed.

  6. Observational Signatures of Magnetic Reconnection

    NASA Technical Reports Server (NTRS)

    Savage, Sabrina

    2014-01-01

    Magnetic reconnection is often referred to as the primary source of energy release during solar flares. Directly observing reconnection occurring in the solar atmosphere, however, is not trivial considering that the scale size of the diffusion region is magnitudes smaller than the observational capabilities of current instrumentation, and coronal magnetic field measurements are not currently sufficient to capture the process. Therefore, predicting and studying observationally feasible signatures of the precursors and consequences of reconnection is necessary for guiding and verifying the simulations that dominate our understanding. I will present a set of such observations, particularly in connection with long-duration solar events, and compare them with recent simulations and theoretical predictions.

  7. Nonlinear Observers for Gyro Calibration

    NASA Technical Reports Server (NTRS)

    Thienel, Julie; Sanner, Robert M.

    2003-01-01

    High precision estimation and control algorithms, to achieve unprecedented levels of pointing accuracy, will be required to support future formation flying missions such as interferometry missions. Achieving high pointing accuracy requires precise knowledge of the spacecraft rotation rate. Typically, the rotation rate is measured by a gyro. The measured rates can be corrupted by errors in alignment and scale factor, gyro biases, and noise. In this work, we present nonlinear observers for gyro calibration. Nonlinear observers are superior to extended or pseudo-linear Kalman filter type approaches for large errors and global stability. Three nonlinear gyro calibration observers are developed. The first observer estimates a constant gyro bias. The second observer estimates scale factor errors. The third observer estimates the gyro alignment for three orthogonal gyros. The convergence properties of all three observers are discussed. Additionally, all three observers are coupled with a nonlinear control algorithm. The stability of each of the resulting closed loop systems is analyzed. The observers are then combined, and the gyro calibration parameters are estimated simultaneously. The stability of the combined observers is addressed, as well as the stability of the resulting closed loop systems. Simulated test results are presented for each scenario. Finally, the nonlinear observers are compared to a pseudo-linear Kalman filter.

  8. The Comparative Method Revisited.

    ERIC Educational Resources Information Center

    Sanford, Glenn M.; Lutterschmidt, William I.; Hutchison, Victor H.

    2002-01-01

    Describes the history of comparative methods and their use in biology as an investigative philosophy. Discusses Bernard's and Krogh's ideas and supports Jorgensen's arguments. Explains conceptual change in the comparative studies which is referred to as "comparative phylogenetic method". (Contains 33 references.) (YDS)

  9. What is comparable in comparative cognition?

    PubMed Central

    Chittka, Lars; Rossiter, Stephen J.; Skorupski, Peter; Fernando, Chrisantha

    2012-01-01

    To understand how complex, or ‘advanced’ various forms of cognition are, and to compare them between species for evolutionary studies, we need to understand the diversity of neural–computational mechanisms that may be involved, and to identify the genetic changes that are necessary to mediate changes in cognitive functions. The same overt cognitive capacity might be mediated by entirely different neural circuitries in different species, with a many-to-one mapping between behavioural routines, computations and their neural implementations. Comparative behavioural research needs to be complemented with a bottom-up approach in which neurobiological and molecular-genetic analyses allow pinpointing of underlying neural and genetic bases that constrain cognitive variation. Often, only very minor differences in circuitry might be needed to generate major shifts in cognitive functions and the possibility that cognitive traits arise by convergence or parallel evolution needs to be taken seriously. Hereditary variation in cognitive traits between individuals of a species might be extensive, and selection experiments on cognitive traits might be a useful avenue to explore how rapidly changes in cognitive abilities occur in the face of pertinent selection pressures. PMID:22927566

  10. Ulysses: UVCS Coordinated Observations

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Poletto, G.; Corti, G.; Simnett, G.; Noci, G.; Romoli, M.; Kohl, J.; Goldstein, B.

    1998-01-01

    We present results from coordinated observations in which instruments on Solar and Heliospheric Observatory (SOHO) and Ulysses were used to measure the density and flow speed of plasma at the Sun and to again measure the same properties of essentially the same plasma in the solar wind. Plasma was sampled by Ultraviolet Coronagraph Spectrometer (UVCS) at 3.5 and 4.5 solar radii and by Ulysses/SWOOPS at 5 AU. Data were acquired during a nearly 2 week period in May-June 1997 at a latitude of 9-10 degrees north of the equator, on the east limb and, hence, in the streamer belt and the source location of slow wind. Density and outflow speed are compared, in order to check for preservation of the near Sun characteristics in the interplanetary medium. By chance, Ulysses was at the very northern edge of the visible streamer belt. Nevertheless, no evidence of fast wind, or mixing with fast wind coming from the northern polar coronal hole, was evident at Ulysses. The morphology of the streamer belt was similar at the beginning and end of the observation period, but was markedly different during the middle of the period. A corresponding change in density (but not flow speed) was noted at Ulysses.

  11. Observer's Interface for JWST Observation Specifications

    NASA Astrophysics Data System (ADS)

    Link, Miranda; Douglas, Robert; Moriarty, Christopher; Roman, Anthony

    2016-01-01

    In support of the launch of the James Webb Space Telescope, various teams at STScI (the Space Telescope Science Institute) have collaborated on how to re-structure the view of a an observing program within the Astronomer's Proposal Tool (APT) to accommodate for the differences between HST and JWST. For HST APT programs, the structure is visit-dominant, and there is one generic form for entering observing information that spans all instruments with their required fields and options. This can result in sometimes showing irrelevant fields to the user for a given observing goal. Also, the generation of mosaicked observations in HST requires the user to manually calculate the position of each tile within the mosaic, accounting for positional offsets and the roll of the telescope, which is a time consuming process. Now, for JWST programs in APT, the description of the observations has been segregated by instrument and mode into discrete observing templates. Each template's form allows instrument specific choices and displays of relevant information. APT will manually manage the number of visits needed to perform the observation. This is particularly useful for mosaics and dithering with JWST. For example, users will select how they would like a mosaic to be tiled at the observation level, and the visits are automatically created. In this, visits have been re-structured to be purely informational; all editing is done at the observation level. These options and concepts are illustrated to future users via the corresponding poster.

  12. AAVSO Solar Observers Worldwide

    NASA Astrophysics Data System (ADS)

    Howe, R.

    2013-06-01

    (Abstract only) For visual solar observers there has been no biological change in the "detector" (human eye) - at century scales (eye + visual cortex) does not change much over time. Our capacity to "integrate" seeing distortions is not just simple averaging! The visual cortex plays an essential role, and until recently only the SDO-HMI (Solar Dynamics Observatory, Helioseismic and Magnetic Imager) has had the capacity to detect the smallest sunspots, called pores. Prior to this the eye was superior to photography and CCD. Imaged data are not directly comparable or substitutable to counts by eye, as the effects of sensor/optical resolution and seeing will have a different influence on the resulting sunspot counts for images when compared to the human eye. Also contributing to the complex task of counting sunspots is differentiating between a sunspot (which is usually defined as having a darker center (umbra) and lighter outer ring (penumbra)) and a pore, made even more complex by the conflicting definitions of the word "pore" in the solar context: "pore" can mean a small spot without penumbra or "pore" can mean a random intergranular blemish that is not a true sunspot. The overall agreement is that the smallest spot size is near 2,000 km or ~3 arc sec, (Loughhead, R. E. and Bray, R. J. 1961, Australian J. Phys., 14, 347). Sunspot size is dictated by granulation dynamics rather than spot size (cancellation of convective motion), and by the lifetime of the pore, which averages from 10 to 30 minutes. There is no specific aperture required for AAVSO observers contributing sunspot observations. However, the detection of the smallest spots is influenced by the resolution of the telescope. Two factors to consider are the theoretical optical resolution (unobstructed aperture), Rayleigh criterion: theta = 138 / D(mm), and Dawes criterion: theta = 116 / D(mm) (http://www.telescope-optics.net/telescope_resolution.htm). However, seeing is variable with time; daytime range will

  13. The role of mobile computed tomography in mass fatality incidents.

    PubMed

    Rutty, Guy N; Robinson, Claire E; BouHaidar, Ralph; Jeffery, Amanda J; Morgan, Bruno

    2007-11-01

    Mobile multi-detector computed tomography (MDCT) scanners are potentially available to temporary mortuaries and can be operational within 20 min of arrival. We describe, to our knowledge, the first use of mobile MDCT for a mass fatality incident. A mobile MDCT scanner attended the disaster mortuary after a five vehicle road traffic incident. Five out of six bodies were successfully imaged by MDCT in c. 15 min per body. Subsequent full radiological analysis took c. 1 h per case. The results were compared to the autopsy examinations. We discuss the advantages and disadvantages of imaging with mobile MDCT in relation to mass fatality work, illustrating the body pathway process, and its role in the identification of the pathology, personal effects, and health and safety hazards. We propose that the adoption of a single modality of mobile MDCT could replace the current use of multiple radiological sources within a mass fatality mortuary.

  14. Oral Reading Observation System Observer's Training Manual.

    ERIC Educational Resources Information Center

    Brady, Mary Ella; And Others

    A self-instructional program for use by teachers of the handicapped, this training manual was developed to teach accurate coding with the Oral Reading Observation System (OROS)an observation system designed to code teacher-pupil verbal interaction during oral reading instruction. The body of the manual is organized to correspond to the nine…

  15. Learning to Observe--Observing to Learn.

    ERIC Educational Resources Information Center

    Cohen, Dorothy H.

    In this address, Dorothy H. Cohen admonishes teachers to remain aware that in the classroom they are both teachers and observers trying to find clues to understanding and interaction. Because teachers are human beings with attitudes and beliefs of their own, it is difficult to be objective in making observations of children. An open mind ready to…

  16. Ram Burn Observations (RAMBO)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Ram Burn Observations (RAMBO) is a Department of Defense experiment that observes shuttle Orbital Maneuvering System engine burns for the purpose of improving plume models. On STS-107 the appropriate sensors will observe selected rendezvous and orbit adjust burns.

  17. SMM Observations of Saturn

    NASA Technical Reports Server (NTRS)

    Schnopper, Herbert; Mushotzky, Richard (Technical Monitor)

    2001-01-01

    During the past year I have participated in a series of team telecons to I plan our observation of Saturn with SMM. The observation, scheduled for this month (September), was canceled and a new observation is being planned for 2002.

  18. Differential comparator cirucit

    DOEpatents

    Hickling, Ronald M.

    1996-01-01

    A differential comparator circuit for an Analog-to-Digital Converter (ADC) or other application includes a plurality of differential comparators and a plurality of offset voltage generators. Each comparator includes first and second differentially connected transistor pairs having equal and opposite voltage offsets. First and second offset control transistors are connected in series with the transistor pairs respectively. The offset voltage generators generate offset voltages corresponding to reference voltages which are compared with a differential input voltage by the comparators. Each offset voltage is applied to the offset control transistors of at least one comparator to set the overall voltage offset of the comparator to a value corresponding to the respective reference voltage. The number of offset voltage generators required in an ADC application can be reduced by a factor of approximately two by applying the offset voltage from each offset voltage generator to two comparators with opposite logical sense such that positive and negative offset voltages are produced by each offset voltage generator.

  19. Compare Gene Calls

    SciTech Connect

    Ecale Zhou, Carol L.

    2016-07-05

    Compare Gene Calls (CGC) is a Python code used for combining and comparing gene calls from any number of gene callers. A gene caller is a computer program that predicts the extends of open reading frames within genomes of biological organisms.

  20. Text File Comparator

    NASA Technical Reports Server (NTRS)

    Kotler, R. S.

    1983-01-01

    File Comparator program IFCOMP, is text file comparator for IBM OS/VScompatable systems. IFCOMP accepts as input two text files and produces listing of differences in pseudo-update form. IFCOMP is very useful in monitoring changes made to software at the source code level.

  1. WORLD SURFACE CURRENTS FROM SHIP'S DRIFT OBSERVATIONS

    SciTech Connect

    Duncan, C.P.; Schladow, S.G.

    1980-11-01

    Over 4 million observations of ship's drift are on file at the U.S. National Oceanographic Data Centre, in Washington, D. C., representing a vast amount of information on ocean surface currents. The observed drift speeds are dependent on the frequency of occurence of the particular current speeds and the frequency of observation. By comparing frequency of observation with the drift speeds observed it is possible to confirm known current patterns and detect singularities in surface currents.

  2. Gd-EOB-DTPA-enhanced 3.0-Tesla MRI findings for the preoperative detection of focal liver lesions: Comparison with iodine-enhanced multi-detector computed tomography

    NASA Astrophysics Data System (ADS)

    Park, Hyong-Hu; Goo, Eun-Hoe; Im, In-Chul; Lee, Jae-Seung; Kim, Moon-Jib; Kwak, Byung-Joon; Chung, Woon-Kwan; Dong, Kyung-Rae

    2012-12-01

    The safety of gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid (Gd-EOB-DTPA) has been confirmed, but more study is needed to assess the diagnostic accuracy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in patients with a hepatocellular carcinoma (HCC) for whom surgical treatment is considered or with a metastatic hepatoma. Research is also needed to examine the rate of detection of hepatic lesions compared to multi-detector computed tomography (MDCT), which is used most frequently to localize and characterize a HCC. Gd-EOB-DTPA-enhanced MRI and iodine-enhanced MDCT imaging were compared for the preoperative detection of focal liver lesions. The clinical usefulness of each method was examined. The current study enrolled 79 patients with focal liver lesions who preoperatively underwent MRI and MDCT. In these patients, there was less than one month between the two diagnostic modalities. Imaging data were taken before and after contrast enhancement in both methods. To evaluate the images, we analyzed the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) in the lesions and the liver parenchyma. To compare the sensitivity of the two methods, we performed a quantitative analysis of the percentage signal intensity of the liver (PSIL) on a high resolution picture archiving and communication system (PACS) monitor (paired-samples t-test, p < 0.05). The enhancement was evaluated based on a consensus of four observers. The enhancement pattern and the morphological features during the arterial and the delayed phases were correlated between the Gd-EOB-DTPA-enhanced MRI findings and the iodine-enhanced MDCT by using an adjusted x2 test. The SNRs, CNRs, and PSIL all had a greater detection rate in Gd-EOB-DTPA enhanced MRI than in iodine-enhanced MDCT. Hepatocyte-selective uptake was observed 20 minutes after the injection in the focal nodular hyperplasia (FNH, 9/9), adenoma (9/10), and highly-differentiated HCC (grade G1, 27/30). Rim

  3. A Week of Observations

    ERIC Educational Resources Information Center

    Colasacco, Jenne

    2011-01-01

    Even the most effective teachers have room to grow, but it's not always easy for principals to give adequate guidance through short observations. High school principal Jenne Colasacco decided to bring more depth to her observations by observing each of her teachers during one class for an entire week. The new observation structure, which included…

  4. The Observation Scientist

    ERIC Educational Resources Information Center

    O'Shaughnessy, Molly

    2016-01-01

    Once the reasons for habitual observation in the classroom have been established, and the intent to observe has been settled, the practical details of observation must be organized. In this article, O'Shaughnessy gives us a model for the implementation of observation. She thoroughly reviews Montessori's work curves and how they can be used to show…

  5. Comparative State Politics.

    ERIC Educational Resources Information Center

    Brooks, Gary H.

    1981-01-01

    Describes a college course dealing with comparative state politics. Students learn about the way in which political scientists employ the study of American state politics as a "laboratory" for the development of scientific explanations of political phenomena. (RM)

  6. Document Update and Compare

    NASA Technical Reports Server (NTRS)

    Knoch, C. F.; Caldwell, D. C.; Caldwell, D. L.

    1983-01-01

    Document Update and Compare programs provide simple computerized documentmaintenance system on Data General NOVA 840 computer. Document Update program allows user to update document either by batch or terminal input. Documents are modified and lists of modifications printed out.

  7. Comparative Packaging Study

    NASA Technical Reports Server (NTRS)

    Perchonok, Michele; Antonini, David

    2008-01-01

    This viewgraph presentation describes a comparative packaging study for use on long duration space missions. The topics include: 1) Purpose; 2) Deliverables; 3) Food Sample Selection; 4) Experimental Design Matrix; 5) Permeation Rate Comparison; and 6) Packaging Material Information.

  8. Mechanical code comparator

    DOEpatents

    Peter, Frank J.; Dalton, Larry J.; Plummer, David W.

    2002-01-01

    A new class of mechanical code comparators is described which have broad potential for application in safety, surety, and security applications. These devices can be implemented as micro-scale electromechanical systems that isolate a secure or otherwise controlled device until an access code is entered. This access code is converted into a series of mechanical inputs to the mechanical code comparator, which compares the access code to a pre-input combination, entered previously into the mechanical code comparator by an operator at the system security control point. These devices provide extremely high levels of robust security. Being totally mechanical in operation, an access control system properly based on such devices cannot be circumvented by software attack alone.

  9. Comparative Magma Oceanography

    NASA Technical Reports Server (NTRS)

    Jones, J. H.

    1999-01-01

    The question of whether the Earth ever passed through a magma ocean stage is of considerable interest. Geochemical evidence strongly suggests that the Moon had a magma ocean and the evidence is mounting that the same was true for Mars. Analyses of martian (SNC) meteorites have yielded insights into the differentiation history of Mars, and consequently, it is interesting to compare that planet to the Earth. Three primary features of Mars contrast strongly to those of the Earth: (i) the extremely ancient ages of the martian core, mantle, and crust (about 4.55 b.y.); (ii) the highly depleted nature of the martian mantle; and (iii) the extreme ranges of Nd isotopic compositions that arise within the crust and depleted mantle. The easiest way to explain the ages and diverse isotopic compositions of martian basalts is to postulate that Mars had an early magma ocean. Cumulates of this magma ocean were later remelted to form the SNC meteorite suite and some of these melts assimilated crustal materials enriched in incompatible elements. The REE pattern of the crust assimilated by these SNC magmas was LREE enriched. If this pattern is typical of the crust as a whole, the martian crust is probably similar in composition to melts generated by small degrees of partial melting (about 5%) of a primitive source. Higher degrees of partial melting would cause the crustal LREE pattern to be essentially flat. In the context of a magma ocean model, where large degrees of partial melting presumably prevailed, the crust would have to be dominated by late-stage, LREE-enriched residual liquids. Regardless of the exact physical setting, Nd and W isotopic evidence indicates that martian geochemical reservoirs must have formed early and that they have not been efficiently remixed since. The important point is that in both the Moon and Mars we see evidence of a magma ocean phase and that we recognize it as such. Several lines of theoretical inference point to an early Earth that was also hot

  10. Observability transition in real networks

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Radicchi, Filippo

    2016-09-01

    We consider the observability model in networks with arbitrary topologies. We introduce a system of coupled nonlinear equations, valid under the locally treelike ansatz, to describe the size of the largest observable cluster as a function of the fraction of directly observable nodes present in the network. We perform a systematic analysis on 95 real-world graphs and compare our theoretical predictions with numerical simulations of the observability model. Our method provides almost perfect predictions in the majority of the cases, even for networks with very large values of the clustering coefficient. Potential applications of our theory include the development of efficient and scalable algorithms for real-time surveillance of social networks, and monitoring of technological networks.

  11. Virtual Optical Comparator

    SciTech Connect

    Thompson, Greg

    2008-10-20

    The Virtual Optical Comparator, VOC, was conceived as a result of the limitations of conventional optical comparators and vision systems. Piece part designs for mechanisms have started to include precision features on the face of parts that must be viewed using a reflected image rather than a profile shadow. The VOC concept uses a computer generated overlay and a digital camera to measure features on a video screen. The advantage of this system is superior edge detection compared to traditional systems. No vinyl charts are procured or inspected. The part size and expensive fixtures are no longer a concern because of the range of the X-Y table of the Virtual Optical Comparator. Product redesigns require only changes to the CAD image overlays; new vinyl charts are not required. The inspection process is more ergonomic by allowing the operator to view the part sitting at a desk rather than standing over a 30 inch screen. The procurement cost for the VOC will be less than a traditional comparator with a much smaller footprint with less maintenance and energy requirements.

  12. Electrophysiological Correlates of Observational Learning in Children

    ERIC Educational Resources Information Center

    Rodriguez Buritica, Julia M.; Eppinger, Ben; Schuck, Nicolas W.; Heekeren, Hauke R.; Li, Shu-Chen

    2016-01-01

    Observational learning is an important mechanism for cognitive and social development. However, the neurophysiological mechanisms underlying observational learning in children are not well understood. In this study, we used a probabilistic reward-based observational learning paradigm to compare behavioral and electrophysiological markers of…

  13. A model for quantitative correction of coronary calcium scores on multidetector, dual source, and electron beam computed tomography for influences of linear motion, calcification density, and temporal resolution: A cardiac phantom study

    SciTech Connect

    Greuter, M. J. W.; Groen, J. M.; Nicolai, L. J.; Dijkstra, H.; Oudkerk, M.

    2009-11-15

    Purpose: The objective of this study is to quantify the influence of linear motion, calcification density, and temporal resolution on coronary calcium determination using multidetector computed tomography (MDCT), dual source CT (DSCT), and electron beam tomography (EBT) and to find a quantitative method which corrects for the influences of these parameters using a linear moving cardiac phantom. Methods: On a robotic arm with artificial arteries with four calcifications of increasing density, a linear movement was applied between 0 and 120 mm/s (step of 10 mm/s). The phantom was scanned five times on 64-slice MDCT, DSCT, and EBT using a standard acquisition protocol. The average Agatston, volume, and mass scores were determined for each velocity, calcification, and scanner. Susceptibility to motion was quantified using a cardiac motion susceptibility (CMS) index. Resemblance to EBT and physical volume and mass was quantified using a {Delta} index. Results: Increasing motion artifacts were observed at increasing velocities on all scanners, with increasing severity from EBT to DSCT to 64-slice MDCT. The calcium score showed a linear dependency on motion from which a correction factor could be derived. This correction factor showed a linear dependency on the mean calcification density with a good fit for all three scoring methods and all three scanners (0.73{<=}R{sup 2}{<=}0.95). The slope and offset of this correction factor showed a linear dependency on temporal resolution with a good fit for all three scoring methods and all three scanners (0.83{<=}R{sup 2}{<=}0.98). CMS was minimal for EBT and increasing values were observed for DSCT and highest values for 64-slice MDCT. CMS was minimal for mass score and increasing values were observed for volume score and highest values for Agatston score. For all densities and scoring methods DSCT showed on average the closest resemblance to EBT calcium scores. When using the correction factor, CMS index decreased on average by

  14. Ensembl comparative genomics resources.

    PubMed

    Herrero, Javier; Muffato, Matthieu; Beal, Kathryn; Fitzgerald, Stephen; Gordon, Leo; Pignatelli, Miguel; Vilella, Albert J; Searle, Stephen M J; Amode, Ridwan; Brent, Simon; Spooner, William; Kulesha, Eugene; Yates, Andrew; Flicek, Paul

    2016-01-01

    Evolution provides the unifying framework with which to understand biology. The coherent investigation of genic and genomic data often requires comparative genomics analyses based on whole-genome alignments, sets of homologous genes and other relevant datasets in order to evaluate and answer evolutionary-related questions. However, the complexity and computational requirements of producing such data are substantial: this has led to only a small number of reference resources that are used for most comparative analyses. The Ensembl comparative genomics resources are one such reference set that facilitates comprehensive and reproducible analysis of chordate genome data. Ensembl computes pairwise and multiple whole-genome alignments from which large-scale synteny, per-base conservation scores and constrained elements are obtained. Gene alignments are used to define Ensembl Protein Families, GeneTrees and homologies for both protein-coding and non-coding RNA genes. These resources are updated frequently and have a consistent informatics infrastructure and data presentation across all supported species. Specialized web-based visualizations are also available including synteny displays, collapsible gene tree plots, a gene family locator and different alignment views. The Ensembl comparative genomics infrastructure is extensively reused for the analysis of non-vertebrate species by other projects including Ensembl Genomes and Gramene and much of the information here is relevant to these projects. The consistency of the annotation across species and the focus on vertebrates makes Ensembl an ideal system to perform and support vertebrate comparative genomic analyses. We use robust software and pipelines to produce reference comparative data and make it freely available. Database URL: http://www.ensembl.org.

  15. Comparative oncology today.

    PubMed

    Paoloni, Melissa C; Khanna, Chand

    2007-11-01

    The value of comparative oncology has been increasingly recognized in the field of cancer research, including the identification of cancer-associated genes; the study of environmental risk factors, tumor biology, and progression; and, perhaps most importantly, the evaluation of novel cancer therapeutics. The fruits of this effort are expected to be the creation of better and more specific drugs to benefit veterinary and human patients who have cancer. The state of the comparative oncology field is outlined in this article, with an emphasis on cancer in dogs.

  16. SVOM Observing Strategy

    NASA Astrophysics Data System (ADS)

    Lachaud, C.; SVOM Consortium

    2016-10-01

    We will present the observing strategy developed to optimize the scientific return of the SVOM mission. We will review the attitude law, the communication processes and the different observation programs (Core Program, ToO and General Program).

  17. Comparable Wages, Inflation, and School Finance Equity

    ERIC Educational Resources Information Center

    Taylor, Lori L.

    2006-01-01

    A Comparable Wage Index (CWI) is an attractive mechanism for measuring geographic variations in the cost of education. A CWI measures uncontrollable variations in educator pay by observing systematic variations in the earnings of comparable workers who are not educators. Together, the 2000 census and the Occupational Employment Statistics survey…

  18. Comparing Teacher Roles in Denmark and England

    ERIC Educational Resources Information Center

    Kelly, Peter; Dorf, Hans; Pratt, Nick; Hohmann, Ulrike

    2014-01-01

    This article reports the findings of a comparative study of teaching in Denmark and England. Its broader aim is to help develop an approach for comparing pedagogy. Lesson observations and interviews identified the range of goals towards which teachers in each country worked and the actions these prompted. These were clustered using the lens of…

  19. Trends in Comparative Education.

    ERIC Educational Resources Information Center

    Altbach, Philip G.

    1991-01-01

    Examines societal and academic factors influencing the development of comparative education since 1945, particularly in the United States. Discusses the dominance of structural functionalism and human capital theory in the 1960s, the recent shift to diverse research orientations and ideologies, and effects of institutional decline and…

  20. Terrestrial Planets: Comparative Planetology

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Papers were presented at the 47th Annual Meteoritical Society Meeting on the Comparative planetology of Terrestrial Planets. Subject matter explored concerning terrestrial planets includes: interrelationships among planets; plaentary evolution; planetary structure; planetary composition; planetary Atmospheres; noble gases in meteorites; and planetary magnetic fields.

  1. Comparative Higher Education: Bibliography

    ERIC Educational Resources Information Center

    Cardozier, V. R.

    This comparative higher education bibliography from the graduate program in Higher Education at University of Texas at Austin provides references with publication dates through 1990 under the following categories: "General and Canada" (85); "Africa (Sub-Sahara)" (23); "Asia" (122); "Australia and New…

  2. Comparative Cognitive Development

    ERIC Educational Resources Information Center

    Matsuzawa, Tetsuro

    2007-01-01

    This paper aims to compare cognitive development in humans and chimpanzees to illuminate the evolutionary origins of human cognition. Comparison of morphological data and life history strongly highlights the common features of all primate species, including humans. The human mother-infant relationship is characterized by the physical separation of…

  3. Teacher Observation Scales.

    ERIC Educational Resources Information Center

    Purdue Univ., Lafayette, IN. Educational Research Center.

    The Teacher Observation Scales include four instruments: Observer Rating Scale (ORS), Reading Strategies Check List, Arithmetic Strategies Check List, and Classroom Description. These instruments utilize trained observers to describe the teaching behavior, instructional strategies and physical characteristics in each classroom. On the ORS, teacher…

  4. Observational biases for transiting planets

    NASA Astrophysics Data System (ADS)

    Kipping, David M.; Sandford, Emily

    2016-12-01

    Observational biases distort our view of nature, such that the patterns we see within a surveyed population of interest are often unrepresentative of the truth we seek. Transiting planets currently represent the most informative data set on the ensemble properties of exoplanets within 1 au of their star. However, the transit method is inherently biased due to both geometric and detection-driven effects. In this work, we derive the overall observational biases affecting the most basic transit parameters from first principles. By assuming a trapezoidal transit and using conditional probability, we infer the expected distribution of these terms both as a joint distribution and in a marginalized form. These general analytic results provide a baseline against which to compare trends predicted by mission-tailored injection/recovery simulations and offer a simple way to correct for observational bias. Our results explain why the observed population of transiting planets displays a non-uniform impact parameter distribution, with a bias towards near-equatorial geometries. We also find that the geometric bias towards observed planets transiting near periastron is attenuated by the longer durations which occur near apoastron. Finally, we predict that the observational bias with respect to ratio-of-radii is super-quadratic, scaling as (RP/R⋆)5/2, driven by an enhanced geometric transit probability and modestly longer durations.

  5. Actors', partners', and observers' perceptions of sarcasm.

    PubMed

    Rockwell, P

    2000-10-01

    This study compared actors', partners', and observers' perceptions of the amount of sarcasm used by participants (n = 80) in videotaped conversations. Significant differences were found among perceptions of actors, partners, and observers. Of the three perspectives, actors perceived themselves as using the greatest amount of sarcasm, followed by partners' perceptions of actors. Observers perceived actors as using the least amount of sarcasm. Correlations conducted to assess whether partners and observers recognized actors' individual attempts at sarcasm during the conversations were generally low.

  6. Comparison with European observations of meteor impact

    SciTech Connect

    Canavan, G.H.

    1997-06-01

    A model for the inference of object size and speed from observations is used to discuss European observations of impact. It compares the observed and predicted breakup altitudes for the objects larger than one meter and observes useful correlations. Trends in magnitude correlate well with measured velocities, altitudes, and trajectories and inferred size and strength parameters, but each parameter is subject to dispute, which can only be addressed when the sensitivity of predictions to uncertainties in these parameters is assessed.

  7. Fast Holographic Comparator

    NASA Technical Reports Server (NTRS)

    Vahey, D. W.

    1982-01-01

    Comparator is integrated-optical system constructed on a LiNb03sub. waveguide chip. Only the laser, lens and detector are external to chip. Aluminized surface gratings serve as input coupler and beam splitter. Light beams striking edges are returned by ordinary total internal reflection. Three operating modes are possible: A "screening" mode, an "identification" mode and a novel "self-subtraction" mode.

  8. Compare Gene Profiles

    SciTech Connect

    2014-05-31

    Compare Gene Profiles (CGP) performs pairwise gene content comparisons among a relatively large set of related bacterial genomes. CGP performs pairwise BLAST among gene calls from a set of input genome and associated annotation files, and combines the results to generate lists of common genes, unique genes, homologs, and genes from each genome that differ substantially in length from corresponding genes in the other genomes. CGP is implemented in Python and runs in a Linux environment in serial or parallel mode.

  9. Comparing Point Clouds

    DTIC Science & Technology

    2004-04-01

    Point clouds are one of the most primitive and fundamental surface representations. A popular source of point clouds are three dimensional shape...acquisition devices such as laser range scanners. Another important field where point clouds are found is in the representation of high-dimensional...framework for comparing manifolds given by point clouds is presented in this paper. The underlying theory is based on Gromov-Hausdorff distances, leading

  10. Banking: shop and compare.

    PubMed

    O'Brien, Jennifer A; DeJarnette, Sherry

    2014-01-01

    There are many reasons to take a critical look at the practice's banking relationship(s)--technology advancements, security measures, improvements in available services, recent banking enhancements designed specifically for medical practices, the impact of the financial crisis on bank ratings and stability, changing practice needs, opportunities for operational automation at the practice--and it is just simply smart to periodically evaluate and compare the features, pricing, and potential savings offered by vendors.

  11. BOOK REVIEW: Observational Cosmology Observational Cosmology

    NASA Astrophysics Data System (ADS)

    Howell, Dale Andrew

    2013-04-01

    Observational Cosmology by Stephen Serjeant fills a niche that was underserved in the textbook market: an up-to-date, thorough cosmology textbook focused on observations, aimed at advanced undergraduates. Not everything about the book is perfect - some subjects get short shrift, in some cases jargon dominates, and there are too few exercises. Still, on the whole, the book is a welcome addition. For decades, the classic textbooks of cosmology have focused on theory. But for every Sunyaev-Zel'dovich effect there is a Butcher-Oemler effect; there are as many cosmological phenomena established by observations, and only explained later by theory, as there were predicted by theory and confirmed by observations. In fact, in the last decade, there has been an explosion of new cosmological findings driven by observations. Some are so new that you won't find them mentioned in books just a few years old. So it is not just refreshing to see a book that reflects the new realities of cosmology, it is vital, if students are to truly stay up on a field that has widened in scope considerably. Observational Cosmology is filled with full-color images, and graphs from the latest experiments. How exciting it is that we live in an era where satellites and large experiments have gathered so much data to reveal astounding details about the origin of the universe and its evolution. To have all the latest data gathered together and explained in one book will be a revelation to students. In fact, at times it was to me. I've picked up modern cosmological knowledge through a patchwork of reading papers, going to colloquia, and serving on grant and telescope allocation panels. To go back and see them explained from square one, and summarized succinctly, filled in quite a few gaps in my own knowledge and corrected a few misconceptions I'd acquired along the way. To make room for all these graphs and observational details, a few things had to be left out. For one, there are few derivations

  12. Observing Double Stars

    NASA Astrophysics Data System (ADS)

    Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

    2012-05-01

    Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

  13. Assessing observational studies of medical treatments

    PubMed Central

    Hartz, Arthur; Bentler, Suzanne; Charlton, Mary; Lanska, Douglas; Butani, Yogita; Soomro, G Mustafa; Benson, Kjell

    2005-01-01

    Background Previous studies have assessed the validity of the observational study design by comparing results of studies using this design to results from randomized controlled trials. The present study examined design features of observational studies that could have influenced these comparisons. Methods To find at least 4 observational studies that evaluated the same treatment, we reviewed meta-analyses comparing observational studies and randomized controlled trials for the assessment of medical treatments. Details critical for interpretation of these studies were abstracted and analyzed qualitatively. Results Individual articles reviewed included 61 observational studies that assessed 10 treatment comparisons evaluated in two studies comparing randomized controlled trials and observational studies. The majority of studies did not report the following information: details of primary and ancillary treatments, outcome definitions, length of follow-up, inclusion/exclusion criteria, patient characteristics relevant to prognosis or treatment response, or assessment of possible confounding. When information was reported, variations in treatment specifics, outcome definition or confounding were identified as possible causes of differences between observational studies and randomized controlled trials, and of heterogeneity in observational studies. Conclusion Reporting of observational studies of medical treatments was often inadequate to compare study designs or allow other meaningful interpretation of results. All observational studies should report details of treatment, outcome assessment, patient characteristics, and confounding assessment. PMID:16137327

  14. Ferroelectric optical image comparator

    DOEpatents

    Butler, M.A.; Land, C.E.; Martin, S.J.; Pfeifer, K.B.

    1993-11-30

    A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image. 7 figures.

  15. Ferroelectric optical image comparator

    DOEpatents

    Butler, Michael A.; Land, Cecil E.; Martin, Stephen J.; Pfeifer, Kent B.

    1993-01-01

    A ferroelectric optical image comparator has a lead lanthanum zirconate titanate thin-film device which is constructed with a semi-transparent or transparent conductive first electrode on one side of the thin film, a conductive metal second electrode on the other side of the thin film, and the second electrode is in contact with a nonconducting substrate. A photoinduced current in the device represents the dot product between a stored image and an image projected onto the first electrode. One-dimensional autocorrelations are performed by measuring this current while displacing the projected image.

  16. Jupiter System Observer

    NASA Technical Reports Server (NTRS)

    Senske, Dave; Kwok, Johnny

    2008-01-01

    This slide presentation reviews the proposed mission for the Jupiter System Observer. The presentation also includes overviews of the mission timeline, science goals, and spacecraftspecifications for the satellite.

  17. BAA Observers' Workshops: Observing the aurora

    NASA Astrophysics Data System (ADS)

    Gavine, D.

    2004-10-01

    Although auroral and upper-atmosphere research is carried out mainly in polar regions by professional scientists, it is still worthwhile for the amateur to observe this beautiful and sometimes spectacular phenomenon for its own sake. Occasionally, however, the BAA Aurora Section is called upon to supply information on displays to a variety of professional organisations, and so it has become important to receive reports, to log them in a standardised method and to maintain a continuous archive which can be consulted by interested persons. Through the kindness and foresight of the late Dr Michael Gadsden this has been done - all our auroral and noctilucent cloud data from the time of Director James Paton in the 1940s up to the present is preserved in the special Balfour Stewart Archive at the Library of Aberdeen University.

  18. Manipulator comparative testing program

    SciTech Connect

    Draper, J.V.; Handel, S.J.; Sundstrom, E.; Herndon, J.N.; Fujita, Y.; Maida, M.

    1986-01-01

    The Manipulator Comparative Testing Program compared performance of selected manipulator systems under typical remote handling conditions. The site of testing was the Remote Operations and Maintenance Demonstration Facility operated by the Consolidated Fuel Reprocessing Program of the Oak Ridge National Laboratory. Three experiment examined differences among manipulator systems from the US and Japan. The manipulator systems included the Meidensha BILARM 83A, Central Research Laboratories' (CRL's) Model M-2, and GCA PaR systems Model 6000. Six manipulator and control mode combinations were evaluated: (a) the BILARM in master-slave mode without force reflection; (b) the BILARM in master-slave mode with force reflection; (c) the Model M-2 in master-slave mode without force reflection; (d) the Model M-2 in master-slave mode with force reflection; (e) the BILARM with switchbox controls; and (f) the PaR 6000 with switchbox controls. The experiments also examined differences between master-slave systems with and without force reflections, and differences between master-slave systems and switchbox-controlled systems.

  19. Comparing pedigree graphs.

    PubMed

    Kirkpatrick, Bonnie; Reshef, Yakir; Finucane, Hilary; Jiang, Haitao; Zhu, Binhai; Karp, Richard M

    2012-09-01

    Pedigree graphs, or family trees, are typically constructed by an expensive process of examining genealogical records to determine which pairs of individuals are parent and child. New methods to automate this process take as input genetic data from a set of extant individuals and reconstruct ancestral individuals. There is a great need to evaluate the quality of these methods by comparing the estimated pedigree to the true pedigree. In this article, we consider two main pedigree comparison problems. The first is the pedigree isomorphism problem, for which we present a linear-time algorithm for leaf-labeled pedigrees. The second is the pedigree edit distance problem, for which we present (1) several algorithms that are fast and exact in various special cases, and (2) a general, randomized heuristic algorithm. In the negative direction, we first prove that the pedigree isomorphism problem is as hard as the general graph isomorphism problem, and that the sub-pedigree isomorphism problem is NP-hard. We then show that the pedigree edit distance problem is APX-hard in general and NP-hard on leaf-labeled pedigrees. We use simulated pedigrees to compare our edit-distance algorithms to each other as well as to a branch-and-bound algorithm that always finds an optimal solution.

  20. Comparison of Diagnostic Accuracy of Radiation Dose-Equivalent Radiography, Multidetector Computed Tomography and Cone Beam Computed Tomography for Fractures of Adult Cadaveric Wrists

    PubMed Central

    Neubauer, Jakob; Benndorf, Matthias; Reidelbach, Carolin; Krauß, Tobias; Lampert, Florian; Zajonc, Horst; Kotter, Elmar; Langer, Mathias; Fiebich, Martin; Goerke, Sebastian M.

    2016-01-01

    Purpose To compare the diagnostic accuracy of radiography, to radiography equivalent dose multidetector computed tomography (RED-MDCT) and to radiography equivalent dose cone beam computed tomography (RED-CBCT) for wrist fractures. Methods As study subjects we obtained 10 cadaveric human hands from body donors. Distal radius, distal ulna and carpal bones (n = 100) were artificially fractured in random order in a controlled experimental setting. We performed radiation dose equivalent radiography (settings as in standard clinical care), RED-MDCT in a 320 row MDCT with single shot mode and RED-CBCT in a device dedicated to musculoskeletal imaging. Three raters independently evaluated the resulting images for fractures and the level of confidence for each finding. Gold standard was evaluated by consensus reading of a high-dose MDCT. Results Pooled sensitivity was higher in RED-MDCT with 0.89 and RED-MDCT with 0.81 compared to radiography with 0.54 (P = < .004). No significant differences were detected concerning the modalities’ specificities (with values between P = .98). Raters' confidence was higher in RED-MDCT and RED-CBCT compared to radiography (P < .001). Conclusion The diagnostic accuracy of RED-MDCT and RED-CBCT for wrist fractures proved to be similar and in some parts even higher compared to radiography. Readers are more confident in their reporting with the cross sectional modalities. Dose equivalent cross sectional computed tomography of the wrist could replace plain radiography for fracture diagnosis in the long run. PMID:27788215

  1. The hubris hypothesis: The downside of comparative optimism displays.

    PubMed

    Hoorens, Vera; Van Damme, Carolien; Helweg-Larsen, Marie; Sedikides, Constantine

    2017-04-01

    According to the hubris hypothesis, observers respond more unfavorably to individuals who express their positive self-views comparatively than to those who express their positive self-views non-comparatively, because observers infer that the former hold a more disparaging view of others and particularly of observers. Two experiments extended the hubris hypothesis in the domain of optimism. Observers attributed less warmth (but not less competence) to, and showed less interest in affiliating with, an individual displaying comparative optimism (the belief that one's future will be better than others' future) than with an individual displaying absolute optimism (the belief that one's future will be good). Observers responded differently to individuals displaying comparative versus absolute optimism, because they inferred that the former held a gloomier view of the observers' future. Consistent with previous research, observers still attributed more positive traits to a comparative or absolute optimist than to a comparative or absolute pessimist.

  2. Guest observer program OAO

    NASA Technical Reports Server (NTRS)

    Coyne, G. V.

    1972-01-01

    The OAO-A2 observations of two Be stars, 60 Cygnus and gamma Cassiopeia, were analyzed. It is shown that unpolarized radiation produced by continuous Balmer emission in the atmospheres of Be stars is significant in the explanation of the polarization observed below the Balmer discontinuity. Available multicolor polarimetry data was also analyzed with respect to interstellar polarization.

  3. Observe Your Shadow

    ERIC Educational Resources Information Center

    Rovšek, Barbara

    2016-01-01

    Observe Your Shadow was the title of an observational experiment that was, among others, conducted in the scope of the past year's (2014-2015) first Slovene science competition for elementary school pupils between the ages of 6 and 13. The main reason for establishing a new science competition was popularization of science and its experimental…

  4. Call for Observations

    NASA Astrophysics Data System (ADS)

    Pilcher, Frederick

    2017-04-01

    Observers who have made visual, photographic, or CCD measurements of positions of minor planets in calendar 2016 are encouraged to report them to this author on or before 2017 April 15. This will be the deadline for receipt of reports which can be included in the "General Report of Position Observations for 2016," to be published in MPB Vol. 44, No. 3.

  5. Crew Earth Observations

    NASA Technical Reports Server (NTRS)

    Runco, Susan

    2009-01-01

    Crew Earth Observations (CEO) takes advantage of the crew in space to observe and photograph natural and human-made changes on Earth. The photographs record the Earth's surface changes over time, along with dynamic events such as storms, floods, fires and volcanic eruptions. These images provide researchers on Earth with key data to better understand the planet.

  6. Becoming a Scientific Observer

    ERIC Educational Resources Information Center

    MacDonald, Greg

    2016-01-01

    Greg MacDonald leaves no stone unturned as he places the complexity of second-plane observation into one coherent vision that includes the fundamentals of self-construction, the essential field of observation (freedom of work within the prepared environment), the role of the human tendencies, the construction of developmental facets, and the…

  7. The Concerned Observer Experiment.

    ERIC Educational Resources Information Center

    Rabiger, Michael

    1991-01-01

    Describes a classroom experiment--the "concerned observer" experiment--for production students that dramatizes basic film language by relating it to several levels of human observation. Details the experiment's three levels, and concludes that film language mimics wide-ranging states of human emotion and ideological persuasion. (PRA)

  8. Observing Classroom Practice

    ERIC Educational Resources Information Center

    Danielson, Charlotte

    2012-01-01

    Classroom observation is a crucial aspect of any system of teacher evaluation. No matter how skilled a teacher is in other aspects of teaching--such as careful planning, working well with colleagues, and communicating with parents--if classroom practice is deficient, that individual cannot be considered a good teacher. Classroom observations can…

  9. Observation Scheduling System

    NASA Technical Reports Server (NTRS)

    Chien, Steve A.; Tran, Daniel Q.; Rabideau, Gregg R.; Schaffer, Steven R.

    2011-01-01

    Software has been designed to schedule remote sensing with the Earth Observing One spacecraft. The software attempts to satisfy as many observation requests as possible considering each against spacecraft operation constraints such as data volume, thermal, pointing maneuvers, and others. More complex constraints such as temperature are approximated to enable efficient reasoning while keeping the spacecraft within safe limits. Other constraints are checked using an external software library. For example, an attitude control library is used to determine the feasibility of maneuvering between pairs of observations. This innovation can deal with a wide range of spacecraft constraints and solve large scale scheduling problems like hundreds of observations and thousands of combinations of observation sequences.

  10. Visual observations over oceans

    NASA Technical Reports Server (NTRS)

    Terry, R. D.

    1979-01-01

    Important factors in locating, identifying, describing, and photographing ocean features from space are presented. On the basis of crew comments and other findings, the following recommendations can be made for Earth observations on Space Shuttle missions: (1) flyover exercises must include observations and photography of both temperate and tropical/subtropical waters; (2) sunglint must be included during some observations of ocean features; (3) imaging remote sensors should be used together with conventional photographic systems to document visual observations; (4) greater consideration must be given to scheduling earth observation targets likely to be obscured by clouds; and (5) an annotated photographic compilation of ocean features can be used as a training aid before the mission and as a reference book during space flight.

  11. Manipulator comparative testing program

    SciTech Connect

    Draper, J.V.; Handel, S.J.; Sundstrom, E.; Herndon, J.N.; Fujita, Y.; Maeda, M.

    1986-01-01

    The Manipulator Comparative Testing Program examined differences among manipulator systems from the United States and Japan. The manipulator systems included the Meidensha BILARM 83A, the Model M-2 of Central Research Laboratories Division of Sargent Industries (CRL), and the GCA Corporation PaR Systems Model 6000. The site of testing was the Remote Operations Maintenance Demonstration (ROMD) facility, operated by the Fuel Recycle Division in the Consolidated Fuel Reprocessing Program at the Oak Ridge National Laboratory (ORNL). In all stages of testing, operators using the CRL Model M-2 manipulator had consistently lower times to completion and error rates than they did using other machines. Performance was second best with the Meidensha BILARM 83A in master-slave mode. Performance with the BILARM in switchbox mode and the PaR 6000 manipulator was approximately equivalent in terms of criteria recorded in testing. These data show no impact of force reflection on task performance.

  12. Comparing new anticoagulants.

    PubMed

    Wooten, James M

    2012-12-01

    For years, the pharmaceutical industry has been trying to find a safe and effective drug to replace warfarin. Although warfarin is an effective anticoagulant, its pharmacology, adverse effects, and risk profiles dictate that patients taking this medication must be monitored judiciously. The US Food and Drug Administration has approved two drugs for commercial use, dabigatran and rivaroxaban, that will compete directly with warfarin for use in specific indications. Because of direct marketing to patients, physicians are being asked to comment on these new medications. This brief review illustrates the data available for the two new drugs when compared to warfarin for the specified indications. For some patients, these drugs may be highly beneficial and offer an excellent alternative to warfarin. For others, warfarin may still be the preferred drug.

  13. Comparing solar energy alternatives

    NASA Astrophysics Data System (ADS)

    White, J. R.

    1984-03-01

    This paper outlines a computational procedure for comparing the merits of alternative processes to convert solar radiation to heat, electrical power, or chemical energy. The procedure uses the ratio of equipment investment to useful work as an index. Comparisons with conversion counterparts based on conventional fuels are also facilitated by examining this index. The procedure is illustrated by comparisons of (1) photovoltaic converters of differing efficiencies; (2) photovoltaic converters with and without focusing concentrators; (3) photovoltaic conversion plus electrolysis vs photocatalysis for the production of hydrogen; (4) photovoltaic conversion plus plasma arcs vs photocatalysis for nitrogen fixation. Estimates for conventionally-fuelled processes are included for comparison. The reasons why solar-based concepts fare poorly in such comparisons are traced to the low energy density of solar radiation and its low stream time factor resulting from the limited number of daylight hours available and clouds obscuring the sun.

  14. Comparing dependent robust correlations.

    PubMed

    Wilcox, Rand R

    2016-11-01

    Let r1 and r2 be two dependent estimates of Pearson's correlation. There is a substantial literature on testing H0  : ρ1  = ρ2 , the hypothesis that the population correlation coefficients are equal. However, it is well known that Pearson's correlation is not robust. Even a single outlier can have a substantial impact on Pearson's correlation, resulting in a misleading understanding about the strength of the association among the bulk of the points. A way of mitigating this concern is to use a correlation coefficient that guards against outliers, many of which have been proposed. But apparently there are no results on how to compare dependent robust correlation coefficients when there is heteroscedasicity. Extant results suggest that a basic percentile bootstrap will perform reasonably well. This paper reports simulation results indicating the extent to which this is true when using Spearman's rho, a Winsorized correlation or a skipped correlation.

  15. Tactile perception during action observation.

    PubMed

    Vastano, Roberta; Inuggi, Alberto; Vargas, Claudia D; Baud-Bovy, Gabriel; Jacono, Marco; Pozzo, Thierry

    2016-09-01

    It has been suggested that tactile perception becomes less acute during movement to optimize motor control and to prevent an overload of afferent information generated during action. This empirical phenomenon, known as "tactile gating effect," has been associated with mechanisms of sensory feedback prediction. However, less attention has been given to the tactile attenuation effect during the observation of an action. The aim of this study was to investigate whether and how the observation of a goal-directed action influences tactile perception as during overt action. In a first experiment, we recorded vocal reaction times (RTs) of participants to tactile stimulations during the observation of a reach-to-grasp action. The stimulations were delivered on different body parts that could be either congruent or incongruent with the observed effector (the right hand and the right leg, respectively). The tactile stimulation was contrasted with a no body-related stimulation (an auditory beep). We found increased RTs for tactile congruent stimuli compared to both tactile incongruent and auditory stimuli. This effect was reported only during the observation of the reaching phase, whereas RTs were not modulated during the grasping phase. A tactile two-alternative forced-choice (2AFC) discrimination task was then conducted in order to quantify the changes in tactile sensitivity during the observation of the same goal-directed actions. In agreement with the first experiment, the tactile perceived intensity was reduced only during the reaching phase. These results suggest that tactile processing during action observation relies on a process similar to that occurring during action execution.

  16. Observing Protein & Energy Nutrition (OPEN) Study

    Cancer.gov

    The Observing Protein and Energy Nutrition (OPEN) Study was designed to assess dietary measurement error by comparing results from self-reported dietary intake data with four dietary biomarkers: doubly labeled water and urinary nitrogen, sodium, and potassium.

  17. Teacher Observation in Mexico.

    ERIC Educational Resources Information Center

    Mayo, Judith A.

    A comparative study was made of Mexican secondary teachers in the Telesecundaria (TS), which utilizes televised instructional programs, and in the Ensenanza Directa (ED), which does not. The aim was to describe the teaching done in the TS system, to compare the two systems, and to examine statistically the relation of teaching and learning…

  18. Mars Observer's costly solitude

    NASA Astrophysics Data System (ADS)

    Travis, John

    1993-09-01

    An evaluation is presented of the ramifications of the loss of contact with the Mars Observer spacecraft in August, 1993; the Observer constituted the first NASA mission to Mars in 17 years. It is noted that most, if not all of the scientists involved with the mission will have to find alternative employment within 6 months. The loss of the Observer will leave major questions concerning the geologic history of Mars, and its turbulent atmospheric circulation, unanswered. A detailed account of the discovery of the loss of communications, the unsuccessful steps taken to rectify the problem, and the financial losses incurred through the failure of the mission, are also given.

  19. Catalog of infrared observations

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Schmitz, M.; Mead, J. M.

    1982-01-01

    The infrared astronomical data base and its principal data product, the catalog of Infrared Observations (CIO), comprise a machine readable library of infrared (1 microns to 1000 microns astronomical observations. To date, over 1300 journal articles and 10 major survey catalogs are included in this data base, which contains about 55,000 individual observations of about 10,000 different infrared sources. Of these, some 8,000 sources are identifiable with visible objects, and about 2,000 do not have known visible counterparts.

  20. The Observable Universe

    NASA Astrophysics Data System (ADS)

    Tran, Kim-Vy

    2009-10-01

    This is a tour of the universe as we have come to understand it through observations taken at many different wavelengths. Stunning images from the Hubble Space Telescope and surprising observations from other space telescopes like Spitzer and Chandra have given us a deeper understanding of the universe, both near and far. Equally important have been observations taken with ground-based observatories such as the Very Large Telescope in Chile. I will describe the most recent advances astronomers have made using these observatories and what we hope to learn in the near future.

  1. Consideration of the Pathological Features of Pediatric Congenital Heart Diseases Which Are Ideally Suitable for Diagnosing With Multidetector-row CT

    PubMed Central

    Hayabuchi, Yasunobu; Inoue, Miki; Watanabe, Noriko; Sakata, Miho; Ohnishi, Tatsuya; Kagami, Shoji

    2011-01-01

    Background A lots of articles published regarding the usefulness of multidetector-row computed tomography (MDCT) in children with congenital heart disease (CHD) mostly describe that it can be an alternative to the invasive catheterization and angiography. The unique diagnostic features of this imaging modality have been largely ignored or disregarded. We described the pathological conditions that cannot be diagnosed by conventional angiography with cardiac catheterization but can be accurately diagnosed by MDCT. Methods We retrospectively reviewed non-ECG-gated MDCT images acquired from 452 children and young adults with CHD between 2005 and 2010 in our institute. In this article, we focused on the diagnostic advantages of MDCT, and indicated five pathological conditions. (1) When Blalock-Taussig shunt total occlusion prevents catheter insertion into the artificial vessel and angiography is ruled out, the peripheral pulmonary artery during the peripheral pulmonary artery can be imaged and diagnosed using MDCT based on blood flow supplied from many small collateral vessels originating from the aorta. (2) The location and protrusion of the device in the vessel after coil embolization to treat patent ductus arteriosus can be accurately visualized by virtual endoscopy using MDCT. (3) Calcification of patches, synthetic blood vessels, and other prostheses that is indistinct on conventional angiograms is clear on MDCT. (4) Simultaneous MDCT observations of the anatomical relationships between arterial and venous systems on the same image can clarify the detail diagnosis for surgical treatment. (5) Compression of the airways by the great vessels and pulmonary segmental emphysematous change can be diagnosed by MDCT. Results and Conclusions Among patients with CHD, MDCT is useful not only as a non-invasive alternative to conventional angiography, but also as a tool for specific morphological diagnoses. In the future, it will be necessary to accumulate experience in the

  2. Ebolavirus comparative genomics

    DOE PAGES

    Jun, Se-Ran; Leuze, Michael R.; Nookaew, Intawat; ...

    2015-07-14

    The 2014 Ebola outbreak in West Africa is the largest documented for this virus. We examine the dynamics of this genome, comparing more than one hundred currently available ebolavirus genomes to each other and to other viral genomes. Based on oligomer frequency analysis, the family Filoviridae forms a distinct group from all other sequenced viral genomes. All filovirus genomes sequenced to date encode proteins with similar functions and gene order, although there is considerable divergence in sequences between the three genera Ebolavirus, Cuevavirus, and Marburgvirus within the family Filoviridae. Whereas all ebolavirus genomes are quite similar (multiple sequences of themore » same strain are often identical), variation is most common in the intergenic regions and within specific areas of the genes encoding the glycoprotein (GP), nucleoprotein (NP), and polymerase (L). We predict regions that could contain epitope-binding sites, which might be good vaccine targets. In conclusion, this information, combined with glycosylation sites and experimentally determined epitopes, can identify the most promising regions for the development of therapeutic strategies.« less

  3. Asynchronous parallel status comparator

    DOEpatents

    Arnold, J.W.; Hart, M.M.

    1992-12-15

    Disclosed is an apparatus for matching asynchronously received signals and determining whether two or more out of a total number of possible signals match. The apparatus comprises, in one embodiment, an array of sensors positioned in discrete locations and in communication with one or more processors. The processors will receive signals if the sensors detect a change in the variable sensed from a nominal to a special condition and will transmit location information in the form of a digital data set to two or more receivers. The receivers collect, read, latch and acknowledge the data sets and forward them to decoders that produce an output signal for each data set received. The receivers also periodically reset the system following each scan of the sensor array. A comparator then determines if any two or more, as specified by the user, of the output signals corresponds to the same location. A sufficient number of matches produces a system output signal that activates a system to restore the array to its nominal condition. 4 figs.

  4. Asynchronous parallel status comparator

    DOEpatents

    Arnold, Jeffrey W.; Hart, Mark M.

    1992-01-01

    Apparatus for matching asynchronously received signals and determining whether two or more out of a total number of possible signals match. The apparatus comprises, in one embodiment, an array of sensors positioned in discrete locations and in communication with one or more processors. The processors will receive signals if the sensors detect a change in the variable sensed from a nominal to a special condition and will transmit location information in the form of a digital data set to two or more receivers. The receivers collect, read, latch and acknowledge the data sets and forward them to decoders that produce an output signal for each data set received. The receivers also periodically reset the system following each scan of the sensor array. A comparator then determines if any two or more, as specified by the user, of the output signals corresponds to the same location. A sufficient number of matches produces a system output signal that activates a system to restore the array to its nominal condition.

  5. What's observable tonight?

    NASA Astrophysics Data System (ADS)

    Relf, G.

    2011-02-01

    The BAA Computing Section's website at http://britastro.org/computing provides a simple graphical display for any date, which shows a large number of objects and enables you to assemble a detailed observing list quickly and easily.

  6. Observing earth from Skylab

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Skylab technology and observations of earth resources are discussed. Special attention was given to application of Skylab data to mapmaking, geology/geodesy, water resources, oceanography, meteorology, and geography/ecology.

  7. Mars Observer instrument complement

    NASA Astrophysics Data System (ADS)

    Komro, Fred G.; Hujber, Frank N.

    1991-10-01

    The mechanical and electrical characteristics and the functional designs of the eight scientific instruments of the Mars Observer's instrument complex are described, and their respective principal investigators and sponsoring institutions are listed. These instruments include a gamma-ray spectrometer, a magnetometer/electron reflectometer, the Mars balloon relay, the Mars Observer camera, the Mars Observer laser altimeter, a pressure modulator infrared radiometer, a thermal emission spectrometer, and an ultrastable oscillator. With these instruments, the Mars Observer will be able to determine the elemental and mineralogical character of Martial surface material; to define globally the topography and the gravitational field; to establish the nature of the magnetic field; to determine the spatial and temporal distribution abundances, sources, and sinks of volatile material and dust over a seasonal cycle; and to explore the structure and circulation of Martian atmosphere.

  8. Comparing NEO Search Telescopes

    NASA Astrophysics Data System (ADS)

    Myhrvold, Nathan

    2016-04-01

    Multiple terrestrial and space-based telescopes have been proposed for detecting and tracking near-Earth objects (NEOs). Detailed simulations of the search performance of these systems have used complex computer codes that are not widely available, which hinders accurate cross-comparison of the proposals and obscures whether they have consistent assumptions. Moreover, some proposed instruments would survey infrared (IR) bands, whereas others would operate in the visible band, and differences among asteroid thermal and visible-light models used in the simulations further complicate like-to-like comparisons. I use simple physical principles to estimate basic performance metrics for the ground-based Large Synoptic Survey Telescope and three space-based instruments—Sentinel, NEOCam, and a Cubesat constellation. The performance is measured against two different NEO distributions, the Bottke et al. distribution of general NEOs, and the Veres et al. distribution of Earth-impacting NEO. The results of the comparison show simplified relative performance metrics, including the expected number of NEOs visible in the search volumes and the initial detection rates expected for each system. Although these simplified comparisons do not capture all of the details, they give considerable insight into the physical factors limiting performance. Multiple asteroid thermal models are considered, including FRM, NEATM, and a new generalized form of FRM. I describe issues with how IR albedo and emissivity have been estimated in previous studies, which may render them inaccurate. A thermal model for tumbling asteroids is also developed and suggests that tumbling asteroids may be surprisingly difficult for IR telescopes to observe.

  9. OSSE Observations of Blazars

    DTIC Science & Technology

    1995-01-01

    jet emission is produced by plasma that is ejected at relativistic speeds from an accreting supermassive black hole . The OSSE observations address...produced by Eddington-limited accretion onto a supermassive black hole . Denoting the observed photon ux by () [photons cm 2 s 11], where the...limit, then even larger black hole masses are implied. An upper limit to the mass is inferred from the emission size scale implied by the variability time

  10. Observing Photons in Space

    NASA Astrophysics Data System (ADS)

    Huber, Martin C. E.; Pauluhn, Anuschka; Timothy, J. Gethyn

    This first chapter of the book "Observing Photons in Space" serves to illustrate the rewards of observing photons in space, to state our aims, and to introduce the structure and the conventions used. The title of the book reflects the history of space astronomy: it started at the high-energy end of the electromagnetic spectrum, where the photon aspect of the radiation dominates. Nevertheless, both the wave and the photon aspects of this radiation will be considered extensively. In this first chapter we describe the arduous efforts that were needed before observations from pointed, stable platforms, lifted by rocket above the Earth"s atmosphere, became the matter of course they seem to be today. This exemplifies the direct link between technical effort -- including proper design, construction, testing and calibration -- and some of the early fundamental insights gained from space observations. We further report in some detail the pioneering work of the early space astronomers, who started with the study of γ- and X-rays as well as ultraviolet photons. We also show how efforts to observe from space platforms in the visible, infrared, sub-millimetre and microwave domains developed and led to today"s emphasis on observations at long wavelengths.

  11. FuzzObserver

    NASA Technical Reports Server (NTRS)

    Howard, Ayanna; Bayard, David

    2006-01-01

    Fuzzy Feature Observation Planner for Small Body Proximity Observations (FuzzObserver) is a developmental computer program, to be used along with other software, for autonomous planning of maneuvers of a spacecraft near an asteroid, comet, or other small astronomical body. Selection of terrain features and estimation of the position of the spacecraft relative to these features is an essential part of such planning. FuzzObserver contributes to the selection and estimation by generating recommendations for spacecraft trajectory adjustments to maintain the spacecraft's ability to observe sufficient terrain features for estimating position. The input to FuzzObserver consists of data from terrain images, including sets of data on features acquired during descent toward, or traversal of, a body of interest. The name of this program reflects its use of fuzzy logic to reason about the terrain features represented by the data and extract corresponding trajectory-adjustment rules. Linguistic fuzzy sets and conditional statements enable fuzzy systems to make decisions based on heuristic rule-based knowledge derived by engineering experts. A major advantage of using fuzzy logic is that it involves simple arithmetic calculations that can be performed rapidly enough to be useful for planning within the short times typically available for spacecraft maneuvers.

  12. Ebolavirus comparative genomics.

    PubMed

    Jun, Se-Ran; Leuze, Michael R; Nookaew, Intawat; Uberbacher, Edward C; Land, Miriam; Zhang, Qian; Wanchai, Visanu; Chai, Juanjuan; Nielsen, Morten; Trolle, Thomas; Lund, Ole; Buzard, Gregory S; Pedersen, Thomas D; Wassenaar, Trudy M; Ussery, David W

    2015-09-01

    The 2014 Ebola outbreak in West Africa is the largest documented for this virus. To examine the dynamics of this genome, we compare more than 100 currently available ebolavirus genomes to each other and to other viral genomes. Based on oligomer frequency analysis, the family Filoviridae forms a distinct group from all other sequenced viral genomes. All filovirus genomes sequenced to date encode proteins with similar functions and gene order, although there is considerable divergence in sequences between the three genera Ebolavirus, Cuevavirus and Marburgvirus within the family Filoviridae. Whereas all ebolavirus genomes are quite similar (multiple sequences of the same strain are often identical), variation is most common in the intergenic regions and within specific areas of the genes encoding the glycoprotein (GP), nucleoprotein (NP) and polymerase (L). We predict regions that could contain epitope-binding sites, which might be good vaccine targets. This information, combined with glycosylation sites and experimentally determined epitopes, can identify the most promising regions for the development of therapeutic strategies.This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

  13. Comparing landslide inventory maps

    NASA Astrophysics Data System (ADS)

    Galli, Mirco; Ardizzone, Francesca; Cardinali, Mauro; Guzzetti, Fausto; Reichenbach, Paola

    Landslide inventory maps are effective and easily understandable products for both experts, such as geomorphologists, and for non experts, including decision-makers, planners, and civil defense managers. Landslide inventories are essential to understand the evolution of landscapes, and to ascertain landslide susceptibility and hazard. Despite landslide maps being compiled every year in the word at different scales, limited efforts are made to critically compare landslide maps prepared using different techniques or by different investigators. Based on the experience gained in 20 years of landslide mapping in Italy, and on the limited literature on landslide inventory assessment, we propose a general framework for the quantitative comparison of landslide inventory maps. To test the proposed framework we exploit three inventory maps. The first map is a reconnaissance landslide inventory prepared for the Umbria region, in central Italy. The second map is a detailed geomorphological landslide map, also prepared for the Umbria region. The third map is a multi-temporal landslide inventory compiled for the Collazzone area, in central Umbria. Results of the experiment allow for establishing how well the individual inventories describe the location, type and abundance of landslides, to what extent the landslide maps can be used to determine the frequency-area statistics of the slope failures, and the significance of the inventory maps as predictors of landslide susceptibility. We further use the results obtained in the Collazzone area to estimate the quality and completeness of the two regional landslide inventory maps, and to outline general advantages and limitations of the techniques used to complete the inventories.

  14. Ebolavirus comparative genomics

    PubMed Central

    Jun, Se-Ran; Leuze, Michael R.; Nookaew, Intawat; Uberbacher, Edward C.; Land, Miriam; Zhang, Qian; Wanchai, Visanu; Chai, Juanjuan; Nielsen, Morten; Trolle, Thomas; Lund, Ole; Buzard, Gregory S.; Pedersen, Thomas D.; Wassenaar, Trudy M.; Ussery, David W.

    2015-01-01

    The 2014 Ebola outbreak in West Africa is the largest documented for this virus. To examine the dynamics of this genome, we compare more than 100 currently available ebolavirus genomes to each other and to other viral genomes. Based on oligomer frequency analysis, the family Filoviridae forms a distinct group from all other sequenced viral genomes. All filovirus genomes sequenced to date encode proteins with similar functions and gene order, although there is considerable divergence in sequences between the three genera Ebolavirus, Cuevavirus and Marburgvirus within the family Filoviridae. Whereas all ebolavirus genomes are quite similar (multiple sequences of the same strain are often identical), variation is most common in the intergenic regions and within specific areas of the genes encoding the glycoprotein (GP), nucleoprotein (NP) and polymerase (L). We predict regions that could contain epitope-binding sites, which might be good vaccine targets. This information, combined with glycosylation sites and experimentally determined epitopes, can identify the most promising regions for the development of therapeutic strategies. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). PMID:26175035

  15. Microwave Oven Observations.

    ERIC Educational Resources Information Center

    Sumrall, William J.; Richardson, Denise; Yan, Yuan

    1998-01-01

    Explains a series of laboratory activities which employ a microwave oven to help students understand word problems that relate to states of matter, collect data, and calculate and compare electrical costs to heat energy costs. (DDR)

  16. Personalized numerical observer

    NASA Astrophysics Data System (ADS)

    Brankov, Jovan G.; Pretorius, P. Hendrik

    2010-02-01

    It is widely accepted that medical image quality should be assessed using task-based criteria, such as humanobserver (HO) performance in a lesion-detection (scoring) task. HO studies are time consuming and cost prohibitive to be used for image quality assessment during development of either reconstruction methods or imaging systems. Therefore, a numerical observer (NO), a HO surrogate, is highly desirable. In the past, we have proposed and successfully tested a NO based on a supervised-learning approach (namely a support vector machine) for cardiac gated SPECT image quality assessment. In the supervised-learning approach, the goal is to identify the relationship between measured image features and HO myocardium defect likelihood scores. Thus far we have treated multiple HO readers by simply averaging or pooling their respective scores. Due to observer variability, this may be suboptimal and less accurate. Therefore, in this work, we are setting our goal to predict individual observer scores independently in the hope to better capture some relevant lesion-detection mechanism of the human observers. This is even more important as there are many ways to get equivalent observer performance (measured by area under receiver operating curve), and simply predicting some joint (average or pooled) score alone is not likely to succeed.

  17. ALMA Observations of TNOs

    NASA Astrophysics Data System (ADS)

    Butler, Bryan J.; Brown, Michael E.

    2016-10-01

    Some of the most fundamental properties of TNOs are still quite poorly constrained, including diameter and density. Observations at long thermal wavelengths, in the millimeter and submillimeter, hold promise for determining these quantities, at least for the largest of these bodies (and notably for those with companions). Knowing this information can then yield clues as to the formation mechanism of these bodies, allowing us to distinguish between pairwise accretion and other formation scenarios.We have used the Atacama Large Millimeter/Submillimeter Array (ALMA) to observe Orcus, Quaoar, Salacia, and 2002 UX25 at wavelengths of 1.3 and 0.8 mm, in order to constrain the sizes of these bodies. We have also used ALMA to make astrometric observations of the Eris-Dysnomia system, in an attempt to measure the wobble of Eris and hence accurately determine its density. Dysnomia should also be directly detectable in those data, separate from Eris (ALMA has sufficient resolution in the configuration in which the observations were made). Results from these observations will be presented and discussed.

  18. Heisenberg's observability principle

    NASA Astrophysics Data System (ADS)

    Wolff, Johanna

    2014-02-01

    Werner Heisenberg's 1925 paper 'Quantum-theoretical re-interpretation of kinematic and mechanical relations' marks the beginning of quantum mechanics. Heisenberg famously claims that the paper is based on the idea that the new quantum mechanics should be 'founded exclusively upon relationships between quantities which in principle are observable'. My paper is an attempt to understand this observability principle, and to see whether its employment is philosophically defensible. Against interpretations of 'observability' along empiricist or positivist lines I argue that such readings are philosophically unsatisfying. Moreover, a careful comparison of Heisenberg's reinterpretation of classical kinematics with Einstein's argument against absolute simultaneity reveals that the positivist reading does not fit with Heisenberg's strategy in the paper. Instead the appeal to observability should be understood as a specific criticism of the causal inefficacy of orbital electron motion in Bohr's atomic model. I conclude that the tacit philosophical principle behind Heisenberg's argument is not a positivistic connection between observability and meaning, but the idea that a theory should not contain causally idle wheels.

  19. ISO observations of asteroids

    NASA Astrophysics Data System (ADS)

    Dotto, E.; Barucci, M. A.; Crovisier, J.; Doressoundiram, A.; Encrenaz, Th.; Fulchignoni, M.; Knacke, R.; Lellouch, E.; Morris, P. W.; Müller, T. G.; Owen, T.

    1999-03-01

    Asteroids were observed by ISO with several instruments (PHT-P, PHT-S and SWS). The aim of these observations was to investigate the asteroid physical and compositional properties. Sixteen asteroids have been observed by PHT-P and PHT-S: with PHT-P we obtained the observations at filters 3.6, 10, 11.5, 25, and 60 μm for 10 asteroids and only at filters 3.6 and 10 μm for the other 6 objects. With PHT-S we obtained simultaneously the 2.5-5 and 5.8-11.6 μm spectral ranges. Four of these asteroids have been also observed with SWS between 5.3 and 45 μm. The first analysis of the obtained spectra has shown some features which suggest the presence of oxides (e.g. magnetite, hematite, etc.) among the surface materials of 10 Hygiea and 308 Polyxo, indicating aqueous alteration on the surfaces of these objects.

  20. Ultraviolet observations of comets

    NASA Technical Reports Server (NTRS)

    Code, A. D.; Houck, T. E.; Lillie, C. F.

    1972-01-01

    The first observations of a comet in the vacuum ultraviolet were obtained on January 14, 1970, when OAO-2 recorded the spectrum of the bright comet Tago-Sato-Kosaka (1969g). The observations revealed, among other things, the predicted extensive hydrogen Lyman alpha halo. OAO-2 continued to collect spectrophotometric measurements of this comet throughout January of that year; a photograph of the nucleus in Lyman alpha revealed finer scale structures. In February of 1970, the bright comet Bennet (1969i) became favorable for space observations. On the basis of the OAO discovery, OGO-V made several measurements of comet Bennet with low spatial resolution photometers. Comet Enke was detected by OGO in January of 1971 at a large heliocentric distance from its Lyman alpha emission.

  1. Visual observations from space

    NASA Technical Reports Server (NTRS)

    Garriott, O. K.

    1979-01-01

    Visual observations from space reveal a number of fascinating natural phenomena of interest to meteorologists and aeronomists, such as aurorae, airglow, aerosol layers, lightning, and atmospheric refraction effects. Other man-made radiation, including city lights and laser beacons, are also of considerable interest. Of course, the most widely used space observations are of the large-scale weather systems viewed each day by millions of people on their local television. From lower altitudes than the geostationary meteorological satellite orbits, obliques and overlapping stereo views are possible, allow height information to be obtained directly, often a key element in the use of the photographs for research purposes. However, this note will discuss only the less common observations mentioned at the beginning of this paragraph.

  2. Observed Barium Emission Rates

    NASA Technical Reports Server (NTRS)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  3. First Observation with AIA

    NASA Astrophysics Data System (ADS)

    Title, Alan

    On February 11, 2010 at about 10:23 EST the Solar Dynamics Observatory (SDO) Atlas 5 launched from the Kennedy Spacecraft Center in central Florida. As this abstract is being written SDO is circling the Earth in preparation for injection into its final geosynchronous orbit. The current schedule plans the Atmospheric Imaging Assembly (AIA) instrument doors will open in 37 days from launch. After a week of checking systems and initial calibration initial observations will begin. During this period several observing sequences will be tested to evaluate normal and various special sequences. At COSPAR initial observations and evaluation of initial sequences will be presented. Because AIA, HMI, and EVE have open data policies the SDO mission represents a huge step forward in the amount and quality of solar data available to the science community. Significant international effort has gone into developing tools for both visualizing and mining the SDO database. Both the data and the data mining tools will be demonstrated.

  4. Observe Your Shadow

    NASA Astrophysics Data System (ADS)

    Rovšek, Barbara

    2016-04-01

    Observe Your Shadow was the title of an observational experiment that was, among others, conducted in the scope of the past year's (2014-2015) first Slovene science competition for elementary school pupils between the ages of 6 and 13. The main reason for establishing a new science competition was popularization of science and its experimental methods, particularly among elementary school students. Elementary school teachers are not generally specialists in science, but rather have (and should have) extremely wide scopes of interests and competencies. By providing them with ideas and instructions for science experiments, we aim to enrich regular school lessons. In the first year alone, the competition took place in over half of Slovene elementary schools, with a total of 9000 participating students. In this paper we shall report about pupils' responses to tasks related to one of the experiments, namely, observation of their shadows on a sunny day.

  5. Observed climate change hotspots

    NASA Astrophysics Data System (ADS)

    Turco, M.; Palazzi, E.; Hardenberg, J.; Provenzale, A.

    2015-05-01

    We quantify climate change hotspots from observations, taking into account the differences in precipitation and temperature statistics (mean, variability, and extremes) between 1981-2010 and 1951-1980. Areas in the Amazon, the Sahel, tropical West Africa, Indonesia, and central eastern Asia emerge as primary observed hotspots. The main contributing factors are the global increase in mean temperatures, the intensification of extreme hot-season occurrence in low-latitude regions and the decrease of precipitation over central Africa. Temperature and precipitation variability have been substantially stable over the past decades, with only a few areas showing significant changes against the background climate variability. The regions identified from the observations are remarkably similar to those defined from projections of global climate models under a "business-as-usual" scenario, indicating that climate change hotspots are robust and persistent over time. These results provide a useful background to develop global policy decisions on adaptation and mitigation priorities over near-time horizons.

  6. Interagency Ocean Observing Committee

    NASA Astrophysics Data System (ADS)

    Rome, N. A.

    2013-12-01

    Decades of focused investment in ocean observing and prediction have produced many examples of substantive societal and economic benefit resulting from improved knowledge of ocean and coastal waters and their behavior. Many complex and difficult questions about the ocean remain, including many that have implications for the lives and livelihoods of millions of Americans. The United States has embarked on a series of efforts to develop an ocean observing system capable of addressing broad societal needs. This system is known as the U.S. Integrated Ocean Observing System (U.S. IOOS). The activities and members of the U.S. IOOS community are broad and complex. There are 18 Federal agencies involved in the U.S. IOOS program, as well as 11 U.S. IOOS Regional Associations that encompass efforts focused in U.S. coastal waters, the Great Lakes, and U.S. territories and their waters in the Pacific and the Caribbean. In addition, there are many Federal and academic scientists representing the U.S. Government in various United Nations-sponsored groups that plan and oversee global ocean observation programs. This diverse community is managed largely through cooperation rather than clear directive or budgetary authority, which has contributed to both the strong growth, and the integration weaknesses, of the U.S. IOOS program. The Interagency Ocean Observation Committee (IOOC) is a dynamic group of federal leaders required by Congress to implement procedural, technical, and scientific requirements to ensure full execution of U.S. IOOS. A major focus for the next decade of the IOOC is to help guide comprehensive processes that more fully integrate the requirements, technologies, data/product development and dissemination, testing and modeling efforts across the regional, national, and global sectors of the U.S. IOOS program. This poster/presentation will increase awareness of IOOC efforts to coordinate physical, chemical, and biological observations -- a complementary objective

  7. The SETI observational plan

    NASA Technical Reports Server (NTRS)

    Berman, A. L.

    1980-01-01

    The SETI (Search for Extraterrestrial Intelligence) Project's primary thrust is to search the microwave region of the spectrum for signals of extraterrestrial intelligent origin. The project will search a well defined volume of search parameter space using existing antennae and a sophisticated data acquisition and analysis system. Two major components are included, the target survey, which will observe at very high sensitivity all attractive stellar candidates within 75 light years of the Sun, and the sky survey, which will observe the entire celestial sphere at a lower sensitivity.

  8. Observations of interstellar zinc

    NASA Technical Reports Server (NTRS)

    Jura, M.; York, D.

    1981-01-01

    The International Ultraviolet Explorer observations of interstellar zinc toward 10 stars are examined. It is found that zinc is at most only slightly depleted in the interstellar medium; its abundance may serve as a tracer of the true metallicity in the gas. The local interstellar medium has abundances that apparently are homogeneous to within a factor of two, when integrated over paths of about 500 pc, and this result is important for understanding the history of nucleosynthesis in the solar neighborhood. The intrinsic errors in detecting weak interstellar lines are analyzed and suggestions are made as to how this error limit may be lowered to 5 mA per target observation.

  9. Radio Observations of Meteors.

    PubMed

    Millman, P M

    1954-08-27

    To summarize, we find that the radio technique of meteor observation enables us to extend the systematic recording of meteor rates down to the 9th or 10th magnitude; to determine satisfactory heights and velocities on a scale previously impossible; to calculate the orbits of meteor showers and individual meteors, in particular those that appear only in the daytime; and to study wind drift and fine structure in the ionosphere. The radio observations have quite definitely indicated that down to the 9th magnitude, corresponding to particles approximately 1 mm in diameter, meteors are members of the solar system and do not come from interstellar space.

  10. The Mars observer camera

    NASA Technical Reports Server (NTRS)

    Malin, M. C.; Danielson, G. E.; Ingersoll, A. P.; Masursky, H.; Veverka, J.; Soulanille, T.; Ravine, M.

    1987-01-01

    A camera designed to operate under the extreme constraints of the Mars Observer Mission was selected by NASA in April, 1986. Contingent upon final confirmation in mid-November, the Mars Observer Camera (MOC) will begin acquiring images of the surface and atmosphere of Mars in September-October 1991. The MOC incorporates both a wide angle system for low resolution global monitoring and intermediate resolution regional targeting, and a narrow angle system for high resolution selective surveys. Camera electronics provide control of image clocking and on-board, internal editing and buffering to match whatever spacecraft data system capabilities are allocated to the experiment. The objectives of the MOC experiment follow.

  11. Observational astrochemistry - Recent results

    NASA Astrophysics Data System (ADS)

    Irvine, W. M.

    More than 80 molecular species have now been observed in the dense interstellar clouds where stars and planets form or in the envelopes expelled by evolved stars. Elemental constituents of these compounds include all of the biogenic elements, H, C, N, O, S and P. In addition, Si is found in several molecules, and a series of metal halides have recently been detected in the outflowing envelope of a nearby carbon star. Knowledge of the chemical reservoirs for the major volatile elements and a comparison between observed molecular abundances and theoretical models are both discussed.

  12. Observations from Sarmizegetusa Sanctuary

    NASA Astrophysics Data System (ADS)

    Barbosu, M.

    2000 years ago, Sarmizegetusa Regia was the capital of ancient Dacia (today: Romania). It is known that the Dacian high priests used the Sanctuary of Sarmizegetusa not only for religious ceremonies, but also for astronomical observations. After having completed geodesic measurements, we analyzed the architecture of the sanctuary with its main points, directions and circles. We discuss here what kind of astronomical observations could have been made with the scientific knowledge of that time. The final section of this work is dedicated to the remarkable resemblance between Sarmizegztusa and Stonehenge.

  13. Student Observational Form.

    ERIC Educational Resources Information Center

    Lindvall, C. M.; And Others

    Lindvall's observation system has been designed to assess elementary school students' behaviors in an Individually Prescribed Instruction (IPI) project. It measures the self-directiveness of the student by determining how pupils use their classroom time when they are not actively being guided by a teacher. The system focuses on student behaviors,…

  14. Classroom Observation Scales.

    ERIC Educational Resources Information Center

    Emmer, Edmund T.

    Nine scales were developed to measure a series of classroom behavior variables derived from a factor analytic study of five observation systems. The scales are multipoint check lists which are behaviorally referenced by different amounts and types of classroom behaviors. The scales measure such aspects of classroom behavior as teacher-initiated…

  15. Observing Community Residences.

    ERIC Educational Resources Information Center

    Taylor, Steven J.; Bogdan, Robert

    The document offers guidelines effectively monitoring the quality of care provided in community residences serving people with disabilities. An initial section offers suggestions on observation and evaluation procedures. The remainder of the document lists possible questions to be asked in 19 areas: location, building and yard, relations with the…

  16. On Observing the Weather

    ERIC Educational Resources Information Center

    Crane, Peter

    2004-01-01

    Rain, sun, snow, sleet, wind... the weather affects everyone in some way every day, and observing weather is a terrific activity to attune children to the natural world. It is also a great way for children to practice skills in gathering and recording information and to learn how to use simple tools in a standardized fashion. What better way to…

  17. Methods Evolved by Observation

    ERIC Educational Resources Information Center

    Montessori, Maria

    2016-01-01

    Montessori's idea of the child's nature and the teacher's perceptiveness begins with amazing simplicity, and when she speaks of "methods evolved," she is unveiling a methodological system for observation. She begins with the early childhood explosion into writing, which is a familiar child phenomenon that Montessori has written about…

  18. Shipboard Weather Observation.

    ERIC Educational Resources Information Center

    Palmaccio, Richard J.

    1983-01-01

    Details of how observers on a moving ship can furnish an accurate report of wind velocity are provided. A method employing vector addition and some trigonometry is covered. Wind velocity is initially indicated through an anemometer and a wind vane. Ships are urged to radio weather data. (MP)

  19. Why Unsharp Observables?

    NASA Astrophysics Data System (ADS)

    Carmeli, Claudio; Heinonen, Teiko; Toigo, Alessandro

    2008-01-01

    We discuss why projection valued measures are not sufficient in the description of position and momentum of a one dimensional particle. A satisfactory solution is offered using positive operator measures. We also argue why the relevant positive operator measures, but not all, may be called unsharp observables.

  20. Climate Observations from Space

    NASA Astrophysics Data System (ADS)

    Briggs, Stephen

    2016-07-01

    The latest Global Climate Observing System (GCOS) Status Report on global climate observations, delivered to the UNFCCC COP21 in November 2016, showed how satellite data are critical for observations relating to climate. Of the 50 Essential Climate Variables (ECVs) identified by GCOS as necessary for understanding climate change, about half are derived only from satellite data while half of the remainder have a significant input from satellites. Hence data from Earth observing satellite systems are now a fundamental requirement for understanding the climate system and for managing the consequences of climate change. Following the Paris Agreement of COP21 this need is only greater. Not only will satellites have to continue to provide data for modelling and predicting climate change but also for a much wider range of actions relating to climate. These include better information on loss and damage, resilience, improved adaptation to change, and on mitigation including information on greenhouse gas emissions. In addition there is an emerging need for indicators of the risks associated with future climate change which need to be better quantified, allowing policy makers both to understand what decisions need to be taken, and to see the consequences of their actions. The presentation will set out some of the ways in which satellite data are important in all aspects of understanding, managing and predicting climate change and how they may be used to support future decisions by those responsible for policy related to managing climate change and its consequences.

  1. Jupiter System Observer

    NASA Technical Reports Server (NTRS)

    Senske, Dave; Prockter, Louise

    2008-01-01

    This slide presentation reviews the scientific philosophy that is guiding the planning behind the Jupiter System Observer (JSO). The JSO would be a long-term platform for studying Jupiter and the complete Jovian system. The goal is to advance the understanding of the fundamental processes of planetary systems, their formation and evolution.

  2. Observing Changes in Nature.

    ERIC Educational Resources Information Center

    Pugh, Ava F.; Dukes, Lenell V.

    1986-01-01

    Presents an overview of a long-term unit centering on observations of biological change. Explains the purpose, procedures, and activities of long-term projects as: watching a plot of land; seeing how a baby grows, and witnessing kitten birth and growth. Suggests additional activities which address the concept of continuity. (ML)

  3. Observability of quarks

    SciTech Connect

    Bjorken, J.D.

    1985-12-01

    Even if stable hadrons with fractional charge do not exist, most of the criteria of observability used for ordinary elementary particles apply in principle to quarks as well. This is especially true in a simplified world containing only hadrons made of top quarks and gluons. In the real world containing light quarks, essential complications do occur, but most of the conclusions survive.

  4. Observations of classical cepheids

    NASA Technical Reports Server (NTRS)

    Pel, J. W.

    1980-01-01

    The observations of classical Cepheids are reviewed. The main progress that has been made is summarized and some of the problems yet to be solved are discussed. The problems include color excesses, calibration of color, duplicity, ultraviolet colors, temperature-color relations, mass discrepancies, and radius determination.

  5. Observer, Process, and Product.

    ERIC Educational Resources Information Center

    Schwartz, Noa

    1996-01-01

    The structure of art as a symbol system is composed of three dimensions: observer, process, and product. Each dimension is described, discussed, and its application to art therapy illustrated through the case study of a 12-year-old boy suffering from a progressive neurological disorder. (LSR)

  6. Comparative Habitability of Transiting Exoplanets

    NASA Astrophysics Data System (ADS)

    Barnes, Rory; Meadows, Victoria S.; Evans, Nicole

    2015-12-01

    Exoplanet habitability is traditionally assessed by comparing a planet’s semimajor axis to the location of its host star’s “habitable zone,” the shell around a star for which Earth-like planets can possess liquid surface water. The Kepler space telescope has discovered numerous planet candidates near the habitable zone, and many more are expected from missions such as K2, TESS, and PLATO. These candidates often require significant follow-up observations for validation, so prioritizing planets for habitability from transit data has become an important aspect of the search for life in the universe. We propose a method to compare transiting planets for their potential to support life based on transit data, stellar properties and previously reported limits on planetary emitted flux. For a planet in radiative equilibrium, the emitted flux increases with eccentricity, but decreases with albedo. As these parameters are often unconstrained, there is an “eccentricity-albedo degeneracy” for the habitability of transiting exoplanets. Our method mitigates this degeneracy, includes a penalty for large-radius planets, uses terrestrial mass-radius relationships, and, when available, constraints on eccentricity to compute a number we call the “habitability index for transiting exoplanets” that represents the relative probability that an exoplanet could support liquid surface water. We calculate it for Kepler ob