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Sample records for mdct generally underestimates

  1. Cardiac Computed Tomography (Multidetector CT, or MDCT)

    MedlinePlus

    ... High Blood Pressure Tools & Resources Stroke More Cardiac Computed Tomography (Multidetector CT, or MDCT) Updated:Sep 3,2015 ... facts MDCT is a very fast type of computed tomography (CT) scan. MDCT creates pictures of the healthy ...

  2. Autopsy radiography: digital radiographs (DR) vs multidetector computed tomography (MDCT) in high-velocity gunshot-wound victims.

    PubMed

    Harcke, H Theodore; Levy, Angela D; Abbott, Robert M; Mallak, Craig T; Getz, John M; Champion, Howard R; Pearse, Lisa

    2007-03-01

    This study compared full-body digital radiography (DR) with multidetector computed tomography (MDCT) in the postmortem evaluation of gunshot wound (GSW) victims. Thirteen consecutive male GSW victims (mean age, 27 years) had full-body DR and MDCT prior to routine autopsy. DR successfully identified all metallic fragments, but MDCT was superior in its ability to precisely determine location because it provided 3-dimensional anatomic localization. In all cases, MDCT more accurately assessed organ injuries and wound tracks. Both DR and MDCT are limited in classifying multiple wounds and major vessel injury, but MDCT is generally superior to DR. MDCT shows significant advantages over DR in the forensic evaluation of GSW victims. This is particularly advantageous for the pathologist retrieving metallic fragments and for describing fracture detail accurately. Use of MDCT instead of radiographs will require medical examiners to become familiar with reading cross-sectional images. PMID:17325457

  3. Imaging of acute thoracic injury: the advent of MDCT screening.

    PubMed

    Mirvis, Stuart E

    2005-10-01

    Chest radiography remains the primary screening study for the assessment of victims of chest trauma, but computed tomography (CT), particularly multidetector CT (MDCT), has progressively changed the imaging approach to these patients. MDCT acquires thinner sections with greater speed, allowing higher quality axial images and nonaxial reformations than conventional or single-detector helical CT. The speed of MDCT, both in acquiring data and in reconstructing images, makes the performance of total body surveys in the blunt polytrauma patient practicable. In general, CT has been well documented to offer major advantages over chest radiography in both screening for thoracic injuries and in characterizing such injuries. This capacity has been enhanced by the application of multichannel data acquisition. The greater sensitivity of MDCT has been well demonstrated in diagnosing vascular and diaphragmatic injuries. This article reviews current concepts of diagnostic imaging in acute chest trauma from blunt force and penetrating mechanisms emphasizing the spectrum of diagnostic imaging findings for various injuries, based primarily on radiographic and CT appearances. The advantages of MDCT for selected injuries are emphasized. PMID:16274001

  4. MDCT of abdominopelvic oncologic emergencies

    PubMed Central

    Tirumani, Sree Harsha; Gunabushanam, Gowthaman; Chintapalli, Kedar N; Ryan, John G; Reinhold, Caroline

    2013-01-01

    Abstract Acute complications arising in abdominopelvic malignancies represent a unique subset of patients presenting to the emergency room. The acute presentation can be due to complications occurring in the tumor itself or visceral or vascular structures harboring the tumor. Multidetector computed tomography (MDCT) is the investigation of choice in the workup of these patients and enables appropriate and timely management. Management of the complication depends primarily on the extent of the underlying malignancy and the involvement of other viscera. The purpose of this article is to depict the imaging features of these complications on MDCT. PMID:23876309

  5. Underestimation of Project Costs

    NASA Technical Reports Server (NTRS)

    Jones, Harry W.

    2015-01-01

    Large projects almost always exceed their budgets. Estimating cost is difficult and estimated costs are usually too low. Three different reasons are suggested: bad luck, overoptimism, and deliberate underestimation. Project management can usually point to project difficulty and complexity, technical uncertainty, stakeholder conflicts, scope changes, unforeseen events, and other not really unpredictable bad luck. Project planning is usually over-optimistic, so the likelihood and impact of bad luck is systematically underestimated. Project plans reflect optimism and hope for success in a supposedly unique new effort rather than rational expectations based on historical data. Past project problems are claimed to be irrelevant because "This time it's different." Some bad luck is inevitable and reasonable optimism is understandable, but deliberate deception must be condemned. In a competitive environment, project planners and advocates often deliberately underestimate costs to help gain project approval and funding. Project benefits, cost savings, and probability of success are exaggerated and key risks ignored. Project advocates have incentives to distort information and conceal difficulties from project approvers. One naively suggested cure is more openness, honesty, and group adherence to shared overall goals. A more realistic alternative is threatening overrun projects with cancellation. Neither approach seems to solve the problem. A better method to avoid the delusions of over-optimism and the deceptions of biased advocacy is to base the project cost estimate on the actual costs of a large group of similar projects. Over optimism and deception can continue beyond the planning phase and into project execution. Hard milestones based on verified tests and demonstrations can provide a reality check.

  6. Comparison between MDCT and Grayscale IVUS in a Quantitative Analysis of Coronary Lumen in Segments with or without Atherosclerotic Plaques

    PubMed Central

    Falcão, João L. A. A.; Falcão, Breno A. A.; Gurudevan, Swaminatha V.; Campos, Carlos M.; Silva, Expedito R.; Kalil-Filho, Roberto; Rochitte, Carlos E.; Shiozaki, Afonso A.; Coelho-Filho, Otavio R.; Lemos, Pedro A.

    2015-01-01

    Background The diagnostic accuracy of 64-slice MDCT in comparison with IVUS has been poorly described and is mainly restricted to reports analyzing segments with documented atherosclerotic plaques. Objectives We compared 64-slice multidetector computed tomography (MDCT) with gray scale intravascular ultrasound (IVUS) for the evaluation of coronary lumen dimensions in the context of a comprehensive analysis, including segments with absent or mild disease. Methods The 64-slice MDCT was performed within 72 h before the IVUS imaging, which was obtained for at least one coronary, regardless of the presence of luminal stenosis at angiography. A total of 21 patients were included, with 70 imaged vessels (total length 114.6 ± 38.3 mm per patient). A coronary plaque was diagnosed in segments with plaque burden > 40%. Results At patient, vessel, and segment levels, average lumen area, minimal lumen area, and minimal lumen diameter were highly correlated between IVUS and 64-slice MDCT (p < 0.01). However, 64-slice MDCT tended to underestimate the lumen size with a relatively wide dispersion of the differences. The comparison between 64-slice MDCT and IVUS lumen measurements was not substantially affected by the presence or absence of an underlying plaque. In addition, 64-slice MDCT showed good global accuracy for the detection of IVUS parameters associated with flow-limiting lesions. Conclusions In a comprehensive, multi-territory, and whole-artery analysis, the assessment of coronary lumen by 64-slice MDCT compared with coronary IVUS showed a good overall diagnostic ability, regardless of the presence or absence of underlying atherosclerotic plaques. PMID:25993595

  7. CT angiography of neonates and infants: comparison of radiation dose and image quality of target mode prospectively ECG-gated 320-MDCT and ungated helical 64-MDCT.

    PubMed

    Jadhav, Siddharth P; Golriz, Farahnaz; Atweh, Lamya A; Zhang, Wei; Krishnamurthy, Rajesh

    2015-02-01

    OBJECTIVE. The purpose of this study was to evaluate the radiation dose and image quality of target mode prospectively ECG-gated volumetric CT angiography (CTA) performed with a 320-MDCT scanner compared with the radiation dose and image quality of ungated helical CTA performed with a 64-MDCT scanner. MATERIALS AND METHODS. An experience with CTA for cardiovascular indications in neonates and infants 0-6 months old was retrospectively assessed. Radiation doses and quantitative and qualitative image quality scores of 28 CTA examinations performed with a 320-MDCT scanner and volumetric target mode prospective ECG gating plus iterative reconstruction (target mode) were compared with the doses and scores of 28 CTA examinations performed with a 64-MDCT scanner and ungated helical scanning plus filtered back projection reconstruction (ungated mode). All target mode studies were performed during free breathing. Seven ungated CTA examinations (25%) were performed with general endotracheal anesthesia. The findings of 17 preoperative CTA examinations performed in target mode were also compared with surgical reports for evaluation of diagnostic accuracy. RESULTS. All studies performed with target mode technique were diagnostic for the main clinical indication. Effective doses were significantly lower in the target mode group (0.51 ± 0.19 mSv) compared with the ungated mode group (4.8 ± 1.4 mSv) (p < 0.0001). Quantitative analysis revealed no statistically significant difference between the two groups with respect to signal-to-noise ratio (of pulmonary artery and aorta) and contrast-to-noise ratio. Subjective image quality was significantly better with target mode than with ungated mode (p < 0.0001). CONCLUSION. Target mode prospectively ECG-gated volumetric scanning with iterative reconstruction performed with a 320-MDCT scanner has several benefits in cardiovascular imaging of neonates and infants, including low radiation dose, improved image quality, high diagnostic

  8. 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.

  9. MDCT evaluation of acute aortic syndrome (AAS).

    PubMed

    Valente, Tullio; Rossi, Giovanni; Lassandro, Francesco; Rea, Gaetano; Marino, Maurizio; Muto, Maurizio; Molino, Antonio; Scaglione, Mariano

    2016-05-01

    Non-traumatic acute thoracic aortic syndromes (AAS) describe a spectrum of life-threatening aortic pathologies with significant implications on diagnosis, therapy and management. There is a common pathway for the various manifestations of AAS that eventually leads to a breakdown of the aortic intima and media. Improvements in biology and health policy and diffusion of technology into the community resulted in an associated decrease in mortality and morbidity related to aortic therapeutic interventions. Hybrid procedures, branched and fenestrated endografts, and percutaneous aortic valves have emerged as potent and viable alternatives to traditional surgeries. In this context, current state-of-the art multidetector CT (MDCT) is actually the gold standard in the emergency setting because of its intrinsic diagnostic value. Management of acute aortic disease has changed with the increasing realization that endovascular therapies may offer distinct advantages in these situations. This article provides a summary of AAS, focusing especially on the MDCT technique, typical and atypical findings and common pitfalls of AAS, as well as recent concepts regarding the subtypes of AAS, consisting of aortic dissection, intramural haematoma, penetrating atherosclerotic ulcer and unstable aortic aneurysm or contained aortic rupture. MDCT findings will be related to pathophysiology, timing and management options to achieve a definite and timely diagnostic and therapeutic definition. In the present article, we review the aetiology, pathophysiology, clinical presentation, outcomes and therapeutic approaches to acute aortic syndromes. PMID:27033344

  10. 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. PMID:20010292

  11. Comparison of conventional radiography and MDCT in suspected scaphoid fractures

    PubMed Central

    Behzadi, Cyrus; Karul, Murat; Henes, Frank Oliver; Laqmani, Azien; Catala-Lehnen, Philipp; Lehmann, Wolfgang; Nagel, Hans-Dieter; Adam, Gerhard; Regier, Marc

    2015-01-01

    AIM: To determine the diagnostic accuracy and radiation dose of conventional radiography and multidetector computed tomography (MDCT) in suspected scaphoid fractures. METHODS: One hundred twenty-four consecutive patients were enrolled in our study who had suffered from a wrist trauma and showed typical clinical symptoms suspicious of an acute scaphoid fracture. All patients had initially undergone conventional radiography. Subsequent MDCT was performed within 10 d because of persisting clinical symptoms. Using the MDCT data as the reference standard, a fourfold table was used to classify the test results. The effective dose and impaired energy were assessed in order to compare the radiation burden of the two techniques. The Wilcoxon test was performed to compare the two diagnostic modalities. RESULTS: Conventional radiography showed 34 acute fractures of the scaphoid in 124 patients (42.2%). Subsequent MDCT revealed a total of 42 scaphoid fractures. The sensitivity of conventional radiography for scaphoid fracture detection was 42.8% and its specificity was 80% resulting in an overall accuracy of 59.6%. Conventional radiography was significantly inferior to MDCT (P < 0.01) concerning scaphoid fracture detection. The mean effective dose of MDCT was 0.1 mSv compared to 0.002 mSv of conventional radiography. CONCLUSION: Conventional radiography is insufficient for accurate scaphoid fracture detection. Regarding the almost negligible effective dose, MDCT should serve as the first imaging modality in wrist trauma. PMID:25628802

  12. Congenital coronary arteries anomalies: review of the literature and multidetector computed tomography (MDCT)-appearance.

    PubMed

    Montaudon, M; Latrabe, V; Iriart, X; Caix, P; Laurent, F

    2007-07-01

    The prevalence of coronary arteries congenital anomalies is 1 to 2% in the general population. Although the spectrum of their clinical manifestations is very broad from total inocuity to lethal, anomalies of coronary arteries need to be recognized by clinicians in certain circumstances: they are the first cause of death in young adults under physical exercise and an abnormal course of a coronary artery can complicate a cardiac surgery. Therefore, a non-invasive test is highly suitable for detecting anomalies of coronary arteries and multidetector computed tomography (MDCT) is likely to be the best one. To understand how anomalies of coronary arteries may occur, we have reviewed the recent literature about their development. Then, the main types of anomalies are presented with their clinical context, and representative MDCT images from our personal database are used for illustration. PMID:17563833

  13. Fusion of MDCT-based endoluminal renderings and endoscopic video

    NASA Astrophysics Data System (ADS)

    Rai, Lav; Higgins, William E.

    2009-02-01

    Early lung cancer can cause structural and color changes to the airway mucosa. A three-dimensional (3D) multidetector CT (MDCT) chest scan provides 3D structural data for airway walls, but no detailed mucosal information. Conversely, bronchoscopy gives color mucosal information, due to airway-wall inflammation and early cancer formation. Unfortunately, each bronchoscopic video image provides only a limited local view of the airway mucosal surface and no 3D structural/location information. The physician has to mentally correlate the video images with each other and the airway surface data to analyze the airway mucosal structure and color. A fusion of the topographical information from the 3D MDCT data and the color information from the bronchoscopic video enables 3D visualization, navigation, localization, and combined color-topographic analysis of the airways. This paper presents a fast method for topographic airway-mucosal surface fusion of bronchoscopic video with 3D MDCT endoluminal views. Tests were performed on phantom sequences, real bronchoscopy patient video, and associated 3D MDCT scans. Results show that we can effectively accomplish mapping over a continuous sequence of airway images spanning several generations of airways in a few seconds. Real-time navigation and visualization of the combined data was performed. The average surface-point mapping error for a phantom case was estimated to be only on the order of 2 mm for 20 mm diameter airway.

  14. Underestimation of periodontitis in NHANES surveys.

    PubMed

    Albandar, Jasim M

    2011-03-01

    The study design of national surveys of periodontal disease often uses partial-mouth examination protocols to rationalize the need for resources so that the collection of data from a large number of subjects can be achieved within the available means without significantly sacrificing precision and validity. Studies show that surveys that use partial examination protocols underestimate the prevalence of periodontitis, and the amount of underestimation varies depending on the number and type of sites examined, the case-definition of periodontal disease, tooth loss, and prevalence and severity of the disease. If a survey uses a partial-mouth examination it is recommended that the amount of underestimation be assessed in the same sample. This could be achieved by performing a full-mouth examination on a randomly selected subsample. Inflation factors should be calculated and used to adjust for the underestimation in disease prevalence because of the use of partial examination. Based on the NHANES III (1988 to 1994) data and adjusting for the bias caused by the examination protocol, it is estimated that approximately half of the United States population aged ≥30 years has periodontitis. PMID:21214340

  15. 3-D segmentation of human sternum in lung MDCT images.

    PubMed

    Pazokifard, Banafsheh; Sowmya, Arcot

    2013-01-01

    A fully automatic novel algorithm is presented for accurate 3-D segmentation of the human sternum in lung multi detector computed tomography (MDCT) images. The segmentation result is refined by employing active contours to remove calcified costal cartilage that is attached to the sternum. For each dataset, costal notches (sternocostal joints) are localized in 3-D by using a sternum mask and positions of the costal notches on it as reference. The proposed algorithm for sternum segmentation was tested on 16 complete lung MDCT datasets and comparison of the segmentation results to the reference delineation provided by a radiologist, shows high sensitivity (92.49%) and specificity (99.51%) and small mean distance (dmean=1.07 mm). Total average of the Euclidean distance error for costal notches positioning in 3-D is 4.2 mm. PMID:24110446

  16. Underestimation of Invasive Meningococcal Disease in Italy

    PubMed Central

    Nieddu, Francesco; Moriondo, Maria; Indolfi, Giuseppe; Canessa, Clementina; Ricci, Silvia; Bianchi, Leila; Serranti, Daniele; Poggi, Giovanni Maria; Resti, Massimo

    2016-01-01

    Knowing the incidence of invasive meningococcal disease (IMD) is essential for planning appropriate vaccination policies. However, IMD may be underestimated because of misdiagnosis or insufficiently sensitive laboratory methods. Using a national molecular surveillance register, we assessed the number of cases misdiagnosed and diagnoses obtained postmortem with real-time PCR (rPCR), and we compared sensitivity of rPCR versus culture-based testing. A total of 222 IMD cases were identified: 11 (42%) of 26 fatal cases had been misdiagnosed or undiagnosed and were reclassified as IMD after rPCR showed meningococcal DNA in all available specimens taken postmortem. Of the samples tested with both rPCR and culture, 58% were diagnosed by using rPCR alone. The underestimation factor associated with the use of culture alone was 3.28. In countries such as Italy, where rPCR is in limited use, IMD incidence may be largely underestimated; thus, assessments of benefits of meningococcal vaccination may be prone to error. PMID:26890305

  17. Coronary lesion complexity assessed by SYNTAX score in 256-slice dual-source MDCT angiography

    PubMed Central

    Yüceler, Zeyneb; Kantarcı, Mecit; Tanboğa, İbrahim Halil; Sade, Recep; Kızrak, Yeşim; Pirimoğlu, Berhan; Bayraktutan, Ümmügülsüm; Oğul, Hayri; Aksakal, Enbiya

    2016-01-01

    PURPOSE The SYNTAX Score (SS) has an important role in grading the complexity of coronary artery disease (CAD) in patients undergoing revascularization. Noninvasive determination of SS prior to invasive coronary angiography (ICA) might optimize patient management. We aimed to evaluate the agreement between ICA and multidetector computed tomography (MDCT) while testing the diagnostic effectiveness of SS-MDCT. METHODS Our study included 108 consecutive patients who underwent both MDCT angiography with a 256-slice dual-source MDCT system and ICA within 14±3 days. SS was calculated for both ICA and MDCT coronary angiography. Spearman’s rank correlation coefficient was used to evaluate the association of SS-MDCT with SS-ICA, and Bland-Altman analysis was performed. RESULTS The degree of agreement between SS-ICA and SS-MDCT was moderate. The mean SS-MDCT was 14.5, whereas the mean SS-ICA was 15.9. After dividing SS into three groups (high [≥33], intermediate [23–32], and low [≤22] subgroups), agreement analysis was repeated. There was a significant correlation between SS-MDCT and SS-ICA in the low SS group (r=0.63, P = 0.043) but no significant correlation in the high SS group (r=0.036, P = 0.677). The inter-test agreement analysis showed at least moderate agreement, whereas thrombotic lesions and the type of bifurcation lesion showed fair agreement. CONCLUSION The calculation of SS-MDCT by adapting SS-ICA parameters achieved nearly the same degree of precision as SS-ICA and was better than SS-ICA, especially in the low SS group. PMID:27328718

  18. Coronary calcium mass scores measured by identical 64-slice MDCT scanners are comparable: a cardiac phantom study.

    PubMed

    Dijkstra, Hildebrand; Greuter, Marcel J W; Groen, Jaap M; Vliegenthart-Proença, Rozemarijn; Renema, Klaasjan W K; de Lange, Frank; Oudkerk, Matthijs

    2010-01-01

    To assess whether absolute mass scores are comparable or differ between identical 64-slice MDCT scanners of the same manufacturer and to compare absolute mass scores to the physical mass and between scan modes using a calcified phantom. A non-moving anthropomorphic phantom with nine calcifications of three sizes and three densities was scanned 30 times on three 64-slice MDCT scanners of manufacturer A and on three 64-slice MDCT scanners of manufacturer B in both sequential and spiral scan mode. The mean mass scores and mass score variabilities of seven calcifications were determined for all scanners; two non-detectable calcifications were omitted. It was analyzed whether identical scanners yielded similar or significantly different mass scores. Furthermore mass scores were compared to the physical mass and mass scores were compared between scan modes. The mass score calibration factor was determined for all scanners. Mass scores obtained on identical scanners were similar for almost all calcifications. Overall, mass score differences between the scanners were small ranging from 1.5 to 3.4% for the total mass scores, and most differences between scanners were observed for high density calcifications. Mass scores were significantly different from the physical mass for almost all calcifications and all scanners. In sequential mode the total physical mass (167.8 mg) was significantly overestimated (+2.3%) for 4 out of 6 scanners. In spiral mode a significant overestimation (+2.5%) was found for system B and a significant underestimation (-1.8%) for two scanners of system A. Mass scores were dependent on the scan mode, for manufacturer A scores were higher in sequential mode and for manufacturer B in spiral mode. For system A using spiral scan mode no differences were found between identical scanners, whereas a few differences were found using sequential mode. For system B the scan mode did not affect the number of different mass scores between identical scanners. Mass

  19. How was the French BSE epidemic underestimated?

    PubMed

    Supervie, Virginie; Costagliola, Dominique

    2006-02-01

    In a previous study, we showed that estimates of the BSE epidemic in France were censored by cattle mortality and by a lack of diagnosis. Indeed, we estimated that 51 300 cattle were infected by the BSE agent between 1987 and 1997, whereas only 103 clinical BSE cases were detected by the passive surveillance system up to June 2000. The question thus arises as to the part played by each form of censorship in this underestimation. Here, using an updated cattle survival distribution, we estimated that 44 800 cattle were infected by the BSE agent between 1987 and 1997, and that 7100 of them showed clinical signs of BSE up to June 2000, showing the low efficiency of the surveillance system. Moreover, between 2087 and 5980 'infectious' cattle, with clinical or preclinical BSE, entered the human food chain before July 1996, the date of the ban on specified bovine offal. PMID:16439340

  20. Numerosity underestimation in sets with illusory contours.

    PubMed

    Kirjakovski, Atanas; Matsumoto, Eriko

    2016-05-01

    People underestimate the numerosity of collections in which a few dots are connected in pairs by task-irrelevant lines. Such configural processing suggests that visual numerosity depends on the perceived scene segments, rather than on the perceived total area occupied by a collection. However, a methodology that uses irrelevant line connections may also introduce unnecessary distraction and variety, or obscure the perception of task-relevant items, given the saliency of the lines. To avoid such potentially confounding variables, we conducted four experiments where the line-connected dots were replaced with collinear inducers of Kanizsa-type illusory contours. Our participants had to compare two simultaneously presented collections and choose the more numerous one. Displays comprised c-shaped inducers and disks (Experiment 1), c-shaped inducers only (Experiments 2 and 4), or closed inducers (Experiment 3). One display always showed a 12- (Experiments 1-3) or 48-item reference pattern (Experiment 4); the other was a test pattern with numerosity varying between 9 and 15 (Experiments 1-3) or 36-60 items (Experiment 4). By manipulating the number of illusory contours in the test patterns, the level of connectedness increased or decreased respectively. The fitted psychometric functions revealed an underestimation that increased with the number of illusory contours in Experiments 1 and 2, but was absent in Experiments 3 and 4, where illusory contours were more difficult to perceive or larger numerosities were used. Results corroborate claims that visual numerosity estimation depends on segmented inputs, but only within moderate numerical ranges. PMID:27038561

  1. CT Hounsfield Numbers of Soft Tissues on Unenhanced Abdominal CT Scans: Variability Between Two Different Manufacturers’ MDCT Scanners

    PubMed Central

    Lamba, Ramit; McGahan, John P.; Corwin, Michael T.; Li, Chin-Shang; Tran, Tien; Seibert, J. Anthony; Boone, John M.

    2016-01-01

    OBJECTIVE The purpose of this study is to determine whether Hounsfield numbers of soft tissues on unenhanced abdominal CT of the same patient vary on repeat scans done on two different manufacturers’ MDCT scanners. MATERIALS AND METHODS A database search was performed to identify patients older than 18 years who underwent unenhanced CT of the abdomen and pelvis performed both on a Volume CT (GE Healthcare) and a Definition AS Plus (Siemens Healthcare) 64-MDCT scanner within 12 months of each other. After excluding those patients for whom Hounsfield unit measurements would be affected by mitigating factors, 48 patients (mean age, 58.8 years) were identified. Hounsfield unit measurements were obtained in nine different soft-tissue anatomic locations on each scan, and the location of these sites was kept identical on each scan pair. Data were analyzed to evaluate Hounsfield unit differences between these scanners. RESULTS In general, there was a low consistency in the Hounsfield unit measurements for each of these sites on scans obtained by the two scanners, with the subcutaneous fat in the left posterolateral flank showing the lowest correlation (intraclass correlation coefficient, 0.198). There were differences in the Hounsfield unit measurements obtained in all anatomic sites on scans obtained by both scanners. Mean Hounsfield unit measurements obtained on the Definition AS Plus scanner were lower than those obtained on the Volume CT scanner, with the intriguing exception of the anterior midline subcutaneous fat Hounsfield unit measurements, which were higher on the Definition AS Plus scanner. All differences were statistically significant (p < 0.05). CONCLUSION Hounsfield unit measurements for unenhanced abdominal soft tissues of the same patient vary between scanners of two common MDCT manufacturers. PMID:25341139

  2. Perinephric abscess caused by ruptured retrocecal appendix: MDCT demonstration

    PubMed Central

    Wani, Nisar Ahmad; Farooq, Mir; Gojwari, Tariq; Kosar, Tasleem

    2010-01-01

    Acute appendicitis may occasionally become extraordinarily complicated and life threatening yet difficult to diagnose. One such presentation is described in a 60-year-old man who was brought to the hospital due to right lumbar pain and fever for the last 15 days. Ultrasonography showed a right perinephric gas and fluid collection. Abdominal computed tomography with multidetector-row CT (MDCT) revealed gas-containing abscess in the right retroperitoneal region involving the perinephric space, extending from the lower pole of the right kidney up to the bare area of the liver. Inflamed retrocecal appendix was seen on thick multiplanar reformat images with its tip at the lower extent of the abscess. Laparotomy and retroperitoneal exploration were performed immediately and a large volume of foul smelling pus was drained. A ruptured retrocecal appendix was confirmed as the cause of the abscess. PMID:20842255

  3. 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.

  4. Diagnostic imaging strategy for MDCT- or MRI-detected breast lesions: use of targeted sonography

    PubMed Central

    2012-01-01

    Background Leading-edge technology such as magnetic resonance imaging (MRI) or computed tomography (CT) often reveals mammographically and ultrasonographically occult lesions. MRI is a well-documented, effective tool to evaluate these lesions; however, the detection rate of targeted sonography varies for MRI detected lesions, and its significance is not well established in diagnostic strategy of MRI detected lesions. We assessed the utility of targeted sonography for multidetector-row CT (MDCT)- or MRI-detected lesions in practice. Methods We retrospectively reviewed 695 patients with newly diagnosed breast cancer who were candidates for breast conserving surgery and underwent MDCT or MRI in our hospital between January 2004 and March 2011. Targeted sonography was performed in all MDCT- or MRI-detected lesions followed by imaging-guided biopsy. Patient background, histopathology features and the sizes of the lesions were compared among benign, malignant and follow-up groups. Results Of the 695 patients, 61 lesions in 56 patients were detected by MDCT or MRI. The MDCT- or MRI-detected lesions were identified by targeted sonography in 58 out of 61 lesions (95.1%). Patients with pathological diagnoses were significantly older and more likely to be postmenopausal than the follow-up patients. Pathological diagnosis proved to be benign in 20 cases and malignant in 25. The remaining 16 lesions have been followed up. Lesion size and shape were not significantly different among the benign, malignant and follow-up groups. Conclusions Approximately 95% of MDCT- or MRI-detected lesions were identified by targeted sonography, and nearly half of these lesions were pathologically proven malignancies in this study. Targeted sonography is a useful modality for MDCT- or MRI-detected breast lesions. PMID:22691539

  5. 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%.

  6. 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.

  7. 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.

  8. The underestimated impact of instabilities with nanoimprint

    NASA Astrophysics Data System (ADS)

    Mayer, A.; Dhima, K.; Wang, S.; Steinberg, C.; Papenheim, M.; Scheer, H.-C.

    2015-11-01

    With nanoimprint, instabilities of the polymeric layer between the substrate and the stamp are observed when incomplete filling of the stamp cavities prevails, resulting in capillary bridges and meandering structures. Experiments show that instabilities may also affect the initial situation of a thermal nanoimprint process. Already at the beginning of the actual imprint step, the polymeric surface may be highly non-uniform, with undulations of the film thickness, polymeric bridges and de-wetted regions; thus, the starting point for imprint may differ substantially from the general expectation of a uniform spin-coated layer. A detailed instability analysis considering the combined effect of van der Waals forces, electrostatic forces and temperature gradients under realistic imprint conditions clearly identifies temperature gradients to be the cause for high initial layer non-uniformities. We found that during heat-up (before imprint) temperature differences of 10 °C may exist between the top and bottom hotplate of a thermal imprint system. These temperature differences result in the non-uniformities of the polymeric layer observed, when stamp and sample are heated under low-pressure contact, where some small but locally arbitrary gaps exist between polymer and stamp. This result asks for a reconsideration of the thermal nanoimprint procedure. It also confirms the high impact of temperature control for uniform, low-defect imprint results; this is critical not only during imprint, but also during heat-up.

  9. A rare congenital anomaly, bridge-like appendiceal fistula to the terminal ileum, demonstrated by MDCT.

    PubMed

    Takeuchi, Kayo; Kosaka, Nobuyuki; Kinoshita, Kazuyuki; Sakai, Toyohiko; Sawai, Katsuji; Imamura, Yoshiaki; Kimura, Hirohiko

    2013-08-01

    Although appendiceal anatomical anomalies are very rare, understanding of the anatomical details of these anomalies is important for surgery. In this case report, we present images from multi-detector row computed tomography (MDCT) and histological findings of a rare anatomical appendiceal anomaly originating from the cecum and opening into the terminal ileum like a bridge. These anatomical details were clearly depicted on MDCT with multi-planar reconstruction. MDCT demonstrated a communication between the appendix and terminal ileum. Histological analysis revealed that a normal mucosal layer was maintained from the appendix to the connected ileum, without any evidence of inflammatory or neoplastic changes, and only thickening of the muscular layer of the appendix was identified. Based on these histological findings, the appendix was considered to represent an anatomical anomaly rather than secondary fistula caused by inflammation or neoplasm, which has not yet been reported. PMID:23247734

  10. 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.

  11. 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. PMID:27399104

  12. US and MDCT findings in a caudal blind ending bifid ureter with calculi

    PubMed Central

    Ustuner, Evren; Atman, Ebru Dusunceli; Yagci, Cemil; Tokatli, Zafer Nida; Uzun, Caglar

    2011-01-01

    Herein we present a rare ureteric duplication anomaly; blind ending bifid ureter with calculi which is asymptomatic unless complicated by infection, reflux, calculi or malignancy. The diagnosis is often missed at intravenous urography (IVU) and US because the ipsilateral ureter and kidney are grossly normal. In this case the diagnosis was established with ultrasound (US) and mainly with multidetector computerized tomography (MDCT) imaging using multiplanar reformats and 3-D reconstructions which were unique to this case. MDCT scans not only revealed the exact diagnosis and anatomic relationships but also ruled out other pathologies included in the differential diagnosis as well, such as ureter and bladder diverticula. PMID:24765338

  13. 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.

  14. 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.

  15. Intussusception in Adults: The Role of MDCT in the Identification of the Site and Cause of Obstruction

    PubMed Central

    Valentini, Viola; Buquicchio, Grazia Loretta; Galluzzo, Michele; Ianniello, Stefania; Di Grezia, Graziella; Ambrosio, Rosa; Trinci, Margherita; Miele, Vittorio

    2016-01-01

    Unlike pediatric intussusception, intestinal intussusception is infrequent in adults and it is often secondary to a pathological condition. The growing use of Multi-Detector Computed Tomography (MDCT) in abdominal imaging has increased the number of radiological diagnoses of intussusception, even in transient and nonobstructing cases. MDCT is well suited to delineate the presence of the disease and provides valuable information about several features, such as the site of intussusception, the intestinal segments involved, and the extent of the intussuscepted bowel. Moreover, MDCT can demonstrate the complications of intussusceptions, represented by bowel wall ischemia and perforation, which are mandatory to promptly refer for surgery. However, not all intussusceptions need an operative treatment. In this paper, we review the current role of MDCT in the diagnosis and management of intussusception in adults, focusing on features, as the presence of a leading point, that may guide an accurate selection of patients for surgery. PMID:26819606

  16. MDCT and MRI for the diagnosis of complex fractures of the tibial plateau: A case control study

    PubMed Central

    XU, YUNQIN; LI, QIANG; SU, PEIHUA; SHEN, TUGANG; ZHU, YAZHONG

    2014-01-01

    The aim of this study was to evaluate the clinical value of multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI) in the diagnosis and treatment of complex fractures of the tibial plateau. A total of 71 patients with complex fractures of the tibial plateau (estimated Schatzker classifications III, V and VI) were included in this study. The X-ray, MDCT and MRI data obtained from the patients were analyzed. MDCT was the most sensitive method in the diagnosis of tibial articular surface collapse, cruciate ligament tibial avulsion fracture, degree of fracture comminution and degree of fracture displacement (P<0.01). MRI was the most sensitive method in the diagnosis of injuries of the cruciate and collateral ligaments, menisci and cartilage peeling of the articular surfaces (P<0.01). MDCT and MRI were demonstrated to be more sensitive than X-rays for the diagnosis of insidious damage around the knee. PMID:24348790

  17. Coronary artery dissection with rupture of aortic valve commissure following type A aortic dissection: the role of 64-slice MDCT.

    PubMed

    Das, K M; Abdou, Sayed M; El-Menyar, Ayman; Ayman, El Menyar; Khulaifi, A A; Nabti, A L

    2008-01-01

    A rare case of bilateral coronary artery dissection with rupture of aortic valve commissure following type A aortic dissection is described. 64-slice multidetector computed tomography (MDCT) was able to demonstrate both this findings along with involvement of other neck vessels. TEE demonstrated the severity and mechanisms of aortic valve damage and assisted the surgeon in valve repair. MDCT has played an invaluable role in the diagnosis of the abnormal details of such life-threatening vascular complications. PMID:18384568

  18. People underestimate the value of persistence for creative performance.

    PubMed

    Lucas, Brian J; Nordgren, Loran F

    2015-08-01

    Across 7 studies, we investigated the prediction that people underestimate the value of persistence for creative performance. Across a range of creative tasks, people consistently underestimated how productive they would be while persisting (Studies 1-3). Study 3 found that the subjectively experienced difficulty, or disfluency, of creative thought accounted for persistence undervaluation. Alternative explanations based on idea quality (Studies 1-2B) and goal setting (Study 4) were considered and ruled out and domain knowledge was explored as a boundary condition (Study 5). In Study 6, the disfluency of creative thought reduced people's willingness to invest in an opportunity to persist, resulting in lower financial performance. This research demonstrates that persistence is a critical determinant of creative performance and that people may undervalue and underutilize persistence in everyday creative problem solving. PMID:26191961

  19. Evolution of imaging in rectal cancer: multimodality imaging with MDCT, MRI, and PET.

    PubMed

    Raman, Siva P; Chen, Yifei; Fishman, Elliot K

    2015-04-01

    Magnetic resonance imaging (MRI), multidetector computed tomography (MDCT), and positron emission tomography (PET) are complementary imaging modalities in the preoperative staging of patients with rectal cancer, and each offers their own individual strengths and weaknesses. MRI is the best available radiologic modality for the local staging of rectal cancers, and can play an important role in accurately distinguishing which patients should receive preoperative chemoradiation prior to total mesorectal excision. Alternatively, both MDCT and PET are considered primary modalities when performing preoperative distant staging, but are limited in their ability to locally stage rectal malignancies. This review details the role of each of these three modalities in rectal cancer staging, and how the three imaging modalities can be used in conjunction. PMID:25830037

  20. MDCT-Guided Transthoracic Needle Aspiration Biopsy of the Lung Using the Transscapular Approach

    SciTech Connect

    Rossi, Umberto G. Seitun, Sara; Ferro, Carlo

    2011-02-15

    The purpose of this study is to report our preliminary experience using MDCT-guided percutaneous transthoracic needle aspiration biopsy using the transscapular approach in the upper posterolateral lung nodules, an area that it is difficult or hazardous to reach with the conventional approach. Five patients underwent CT-guided percutaneous transthoracic needle aspiration biopsy of the lung via the transscapular approach. A coaxial needle technique was used in all patients. Biopsy was successful in all patients. No major complications were encountered. One patient developed a minimal pneumothorax next to the lesion immediately after biopsy, which resolved spontaneously. MDCT-guided percutaneous transthoracic needle aspiration biopsy of the lung via the transscapular approach is an effective and safe procedure that reduces the risk of pneumothorax in selected patients.

  1. 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.

  2. Evolution of imaging in rectal cancer: multimodality imaging with MDCT, MRI, and PET

    PubMed Central

    Chen, Yifei; Fishman, Elliot K.

    2015-01-01

    Magnetic resonance imaging (MRI), multidetector computed tomography (MDCT), and positron emission tomography (PET) are complementary imaging modalities in the preoperative staging of patients with rectal cancer, and each offers their own individual strengths and weaknesses. MRI is the best available radiologic modality for the local staging of rectal cancers, and can play an important role in accurately distinguishing which patients should receive preoperative chemoradiation prior to total mesorectal excision. Alternatively, both MDCT and PET are considered primary modalities when performing preoperative distant staging, but are limited in their ability to locally stage rectal malignancies. This review details the role of each of these three modalities in rectal cancer staging, and how the three imaging modalities can be used in conjunction. PMID:25830037

  3. Underestimation and undertreatment of pain in HIV disease: multicentre study.

    PubMed Central

    Larue, F.; Fontaine, A.; Colleau, S. M.

    1997-01-01

    OBJECTIVE: To measure the prevalence, severity, and impact of pain on quality of life for HIV patients; to identify factors associated with undertreatment of pain. DESIGN: Multicentre cross sectional survey. SETTINGS: 34 HIV treatment facilities, including inpatient hospital wards, day hospitals, and ambulatory care clinics, in 13 cities throughout France. SUBJECTS: 315 HIV patients at different stages of the disease. MAIN OUTCOME MEASURES: Patients: recorded presence and severity of pain and rated quality of life. Doctors: reported disease status, estimate of pain severity, and analgesic treatment ordered. RESULTS: From 30% (17/56) of outpatients to 62% (73/118) of inpatients reported pain due to HIV disease. Pain severity significantly decreased patients' quality of life. Doctors underestimated pain severity in 52% (70/135) of HIV patients reporting pain. Underestimation of pain severity was more likely for patients who reported moderate (odds ratio 24) or severe pain (165) and less likely for patients whose pain source was identified or who were perceived as more depressed. Of the patients reporting moderate or severe pain, 57% (61/107) did not receive any analgesic treatment; only 22% (23/107) received at least weak opioids. Likelihood of analgesic prescription increased when doctors estimated pain to be more severe and regarded patients as sicker. CONCLUSIONS: Pain is a common and debilitating symptom of HIV disease which is gravely underestimated and undertreated. PMID:9001475

  4. Reperfusion injury components and manifestations determined by cardiovascular MR and MDCT imaging

    PubMed Central

    Saeed, Maythem; Hetts, Steve; Wilson, Mark

    2010-01-01

    Advances in magnetic resonance (MR) and computed tomography (CT) imaging have improved visualization of acute and scar infarct. Over the past decade, there have been and continues to be many significant technical advancements in cardiac MR and multi-detector computed tomography (MDCT) technologies. The strength of MR imaging relies on a variety of pulse sequences and the ability to noninvasively provide information on myocardial structure, function and perfusion in a single imaging session. The recent technical developments may also allow CT technologies to rise to the forefront for evaluating clinical ischemic heart disease. Components of reperfusion injury including myocardial edema, hemorrhage, calcium deposition and microvascular obstruction (MO) have been demonstrated using MR and CT technologies. MR imaging can be used serially and noninvasively in assessing acute and chronic consequences of reperfusion injury because there is no radiation exposure or administration of radioactive materials. MDCT is better suited for assessing coronary artery stenosis and as an alternative technique for assessing viability in patients where MR imaging is contraindicated. Changes in left ventricular (LV) volumes and function measured on cine MR are directly related to infarct size measured on delayed contrast enhanced images. Recent MR studies found that transmural infarct, MO and peri-infarct zone are excellent predictors of poor post-infarct recovery and mortality. Recent MR studies provided ample evidence that growth factor genes and stem cells delivered locally have beneficial effects on myocardial viability, perfusion and function. The significance of deposited calcium in acute infarct detected on MDCT requires further studies. Cardiac MR and MDCT imaging have the potential for assessing reperfusion injury components and manifestations. PMID:21160735

  5. Individuals Underestimate Moderate and Vigorous Intensity Physical Activity

    PubMed Central

    Canning, Karissa L.; Brown, Ruth E.; Jamnik, Veronica K.; Salmon, Art; Ardern, Chris I.; Kuk, Jennifer L.

    2014-01-01

    Background It is unclear whether the common physical activity (PA) intensity descriptors used in PA guidelines worldwide align with the associated percent heart rate maximum method used for prescribing relative PA intensities consistently between sexes, ethnicities, age categories and across body mass index (BMI) classifications. Objectives The objectives of this study were to determine whether individuals properly select light, moderate and vigorous intensity PA using the intensity descriptions in PA guidelines and determine if there are differences in estimation across sex, ethnicity, age and BMI classifications. Methods 129 adults were instructed to walk/jog at a “light,” “moderate” and “vigorous effort” in a randomized order. The PA intensities were categorized as being below, at or above the following %HRmax ranges of: 50–63% for light, 64–76% for moderate and 77–93% for vigorous effort. Results On average, people correctly estimated light effort as 51.5±8.3%HRmax but underestimated moderate effort as 58.7±10.7%HRmax and vigorous effort as 69.9±11.9%HRmax. Participants walked at a light intensity (57.4±10.5%HRmax) when asked to walk at a pace that provided health benefits, wherein 52% of participants walked at a light effort pace, 19% walked at a moderate effort and 5% walked at a vigorous effort pace. These results did not differ by sex, ethnicity or BMI class. However, younger adults underestimated moderate and vigorous intensity more so than middle-aged adults (P<0.05). Conclusion When the common PA guideline descriptors were aligned with the associated %HRmax ranges, the majority of participants underestimated the intensity of PA that is needed to obtain health benefits. Thus, new subjective descriptions for moderate and vigorous intensity may be warranted to aid individuals in correctly interpreting PA intensities. PMID:24835105

  6. [Chronic kidney disease, an often underestimated complication of diabetes].

    PubMed

    Sauvanet, Jean-Pierre

    2015-03-01

    Diabetic kidney chronic kidney disease, an often underestimated complication of diabetes. Diabetic kidney disease is a serious complication which can evolve into severe chronic kidney disease (CKD), or even end-stage renal disease (ESRD). It impacts on the patient's quality of life and that of their family and significantly increases the cost of care. The development and progression of chronic kidney disease is prevented by strictly controlling blood sugar levels and cardiovascular risk factors as well as monitoring the markers of kidney disease. In the case of CKD, treatment may need to be adapted. PMID:26036123

  7. Does WISC-IV Underestimate the Intelligence of Autistic Children?

    PubMed

    Nader, Anne-Marie; Courchesne, Valérie; Dawson, Michelle; Soulières, Isabelle

    2016-05-01

    Wechsler Intelligence Scale for Children (WISC) is widely used to estimate autistic intelligence (Joseph in The neuropsychology of autism. Oxford University Press, Oxford, 2011; Goldstein et al. in Assessment of autism spectrum disorders. Guilford Press, New York, 2008; Mottron in J Autism Dev Disord 34(1):19-27, 2004). However, previous studies suggest that while WISC-III and Raven's Progressive Matrices (RPM) provide similar estimates of non-autistic intelligence, autistic children perform significantly better on RPM (Dawson et al. in Psychol Sci 18(8):657-662, doi: 10.1111/j.1467-9280.2007.01954.x , 2007). The latest WISC version introduces substantial changes in subtests and index scores; thus, we asked whether WISC-IV still underestimates autistic intelligence. Twenty-five autistic and 22 typical children completed WISC-IV and RPM. Autistic children's RPM scores were significantly higher than their WISC-IV FSIQ, but there was no significant difference in typical children. Further, autistic children showed a distinctively uneven WISC-IV index profile, with a "peak" in the new Perceptual Reasoning Index. In spite of major changes, WISC-IV FSIQ continues to underestimate autistic intelligence. PMID:25308198

  8. Templeton prediction model underestimates IVF success in an external validation.

    PubMed

    van Loendersloot, L L; van Wely, M; Repping, S; van der Veen, F; Bossuyt, P M M

    2011-06-01

    Prediction models for IVF can be used to identify couples that will benefit from IVF treatment. Currently there is only one prediction model with a good predictive performance that can be used for predicting pregnancy chances after IVF. That model was developed almost 15 years ago and since IVF has progressed substantially during the last two decades it is questionable whether the model is still valid in current clinical practice. The objective of this study was to validate the prediction model of Templeton for calculating pregnancy chances after IVF. The performance of the prediction model was assessed in terms of discrimination, i.e. the area under the receiver operation characteristic (ROC) curve and calibration. Likely causes for miscalibration were evaluated by refitting the Templeton model to the study data. The area under the ROC curve for the Templeton model was 0.61. Calibration showed a significant and systematic underestimation of success in IVF. Although the Templeton model can distinguish somewhat between women with a high and low success rate in IVF, it systematically underestimates pregnancy chances and has therefore no real value for current IVF practice. PMID:21493154

  9. Differences of Upper Airway Morphology According to Obesity: Study with Cephalometry and Dynamic MD-CT

    PubMed Central

    Kim, Tae Hoon; Chun, Bum Soo; Lee, Ho Won

    2010-01-01

    Objectives We investigated difference of parameters of polysomnography, cephalometry and dynamic multi-detector computerized tomography (MD-CT) in wake and sleep states according to obesity. Methods We evaluated 93 patients who underwent polysomnography and cephalometry. MD-CT was performed in 68 of these 93 patients. Fifty-nine and 34 patients were classified as obese and non-obese, with obesity defined as BMI ≥25. Cephalometry results were analyzed for 12 variables. Using the MD-CT, we evaluated dynamic upper airway morphology in wake and sleep states and divided the upper airway into four parts named as high retropalatal (HRP), low retropalatal (LRP), high retroglossal (HRG), and low retroglossal (LRG). A minimal cross sectional area (mCSA) and collapsibility index (CI) were calculated for each airway level. Results Diastolic blood pressure (P=0.0005), neck circumference (P<0.0001), and apnea-hypopnea index (P<0.0001) were statistically significantly different between the obese and non-obese group. Among 12 cephalometric variables, there was a significant difference in only the distance from mandibular plane to hyoid bone (P=0.003). There was statistical difference in CI of HRG and LRG in sleep state (P=0.0449, 0.0281) but no difference in mCSA in wake and sleep states. Conclusion The obese group had more severe sleep apnea than the non-obese group. We believe that the increased severity of apnea in the obese group may be have been due to increased collapsibility of the upper airway rather than decreased size of the upper airway. PMID:20978543

  10. Effects of two different anesthetic protocols on 64-MDCT coronary angiography in dogs.

    PubMed

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

    2015-01-01

    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/min in humans. The purpose of this prospective study was to compare effects of two different clinically applicable anesthetic protocols on cardiovascular parameters and 64-MDCT-CA quality in 10 healthy dogs. Scan protocols and bolus volumes were standardized. Image evaluations were performed in random order by a board-certified veterinary radiologist who was unaware of anesthetic protocols used. Heart rate during image acquisition did not differ between protocols (P = 1), with 80.6 ± 7.5 bpm for protocol A and 79.2 ± 14.2 bpm for protocol B. Mean blood pressure was significantly higher (P > 0.05) using protocol B (protocol A 62.9 ± 9.1 vs. protocol B 72.4 ± 15.9 mmHg). The R-R intervals allowing for best depiction of individual coronary artery segments were found in the end diastolic period and varied between the 70% and 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 mainly affected the distal segments. No significant differences were identified between the two protocols for optimal reconstruction interval, diagnostic quality and measured length individual segments, or proximal diameter of the coronary arteries (P = 1). Findings indicated that, when used with a standardized bolus volume, both of these anesthetic protocols yielded diagnostic quality coronary 64-MDCT-CA exams in healthy dogs. PMID:25065815

  11. Mucosal leishmaniasis: an underestimated presentation of a neglected disease.

    PubMed

    Strazzulla, Alessio; Cocuzza, Salvatore; Pinzone, Marilia Rita; Postorino, Maria Concetta; Cosentino, Stefano; Serra, Agostino; Cacopardo, Bruno; Nunnari, Giuseppe

    2013-01-01

    We present a review of current knowledge about mucosal leishmaniasis (ML). Although involvement of mucous membranes is classically admitted in New World leishmaniasis, particularly occurring in infection by Leishmania (L.) braziliensis species complex, ML is also a possible presentation of Old World leishmaniasis, in either L. donovani or L. major species complex infections. Thus, ML has to be considered not only as a Latin American disease but as an Old and New World disease. We describe ML epidemiology, pathogenesis, clinics, diagnosis, and therapy. Considering both its highly disfiguring lesions and its possible lethal outcome, ML should not be underestimated by physicians. Moreover, leishmaniasis is expected to increase its burden in many countries as sandfly vector distribution is widespreading towards non-endemic areas. Finally, the lack of clear understanding of ML pathogenesis and the absence of effective human vaccines strongly claim for more research. PMID:23853773

  12. Climate change velocity underestimates climate change exposure in mountainous regions

    PubMed Central

    Dobrowski, Solomon Z.; Parks, Sean A.

    2016-01-01

    Climate change velocity is a vector depiction of the rate of climate displacement used for assessing climate change impacts. Interpreting velocity requires an assumption that climate trajectory length is proportional to climate change exposure; longer paths suggest greater exposure. However, distance is an imperfect measure of exposure because it does not quantify the extent to which trajectories traverse areas of dissimilar climate. Here we calculate velocity and minimum cumulative exposure (MCE) in degrees Celsius along climate trajectories for North America. We find that velocity is weakly related to MCE; each metric identifies contrasting areas of vulnerability to climate change. Notably, velocity underestimates exposure in mountainous regions where climate trajectories traverse dissimilar climates, resulting in high MCE. In contrast, in flat regions velocity is high where MCE is low, as these areas have negligible climatic resistance to movement. Our results suggest that mountainous regions are more climatically isolated than previously reported. PMID:27476545

  13. [Aedes albopictus in Italy: an underestimated health problem].

    PubMed

    Romi, R

    2001-01-01

    Since 1990, Ae. albopictus has spread in 9 regions and 30 provinces of the country. This species was introduced in Italy in shipments of scrap tires form the USA. In Italy, Ae. albopictus is the major biting pest throughout much of its range and, although there is no evidence that this mosquito is the vector of human disease in the country, the species might be involved in the transmission of some arboviruses which have been reported in the Mediterranean Basin. Aim of this paper is to provide an update on the distribution of Ae. albopictus in Italy and to renew the interest in a problem frequently underestimated. Public health implications after a ten-year presence of the species are also discussed. PMID:11758282

  14. Climate change velocity underestimates climate change exposure in mountainous regions

    NASA Astrophysics Data System (ADS)

    Dobrowski, Solomon Z.; Parks, Sean A.

    2016-08-01

    Climate change velocity is a vector depiction of the rate of climate displacement used for assessing climate change impacts. Interpreting velocity requires an assumption that climate trajectory length is proportional to climate change exposure; longer paths suggest greater exposure. However, distance is an imperfect measure of exposure because it does not quantify the extent to which trajectories traverse areas of dissimilar climate. Here we calculate velocity and minimum cumulative exposure (MCE) in degrees Celsius along climate trajectories for North America. We find that velocity is weakly related to MCE; each metric identifies contrasting areas of vulnerability to climate change. Notably, velocity underestimates exposure in mountainous regions where climate trajectories traverse dissimilar climates, resulting in high MCE. In contrast, in flat regions velocity is high where MCE is low, as these areas have negligible climatic resistance to movement. Our results suggest that mountainous regions are more climatically isolated than previously reported.

  15. Climate change velocity underestimates climate change exposure in mountainous regions.

    PubMed

    Dobrowski, Solomon Z; Parks, Sean A

    2016-01-01

    Climate change velocity is a vector depiction of the rate of climate displacement used for assessing climate change impacts. Interpreting velocity requires an assumption that climate trajectory length is proportional to climate change exposure; longer paths suggest greater exposure. However, distance is an imperfect measure of exposure because it does not quantify the extent to which trajectories traverse areas of dissimilar climate. Here we calculate velocity and minimum cumulative exposure (MCE) in degrees Celsius along climate trajectories for North America. We find that velocity is weakly related to MCE; each metric identifies contrasting areas of vulnerability to climate change. Notably, velocity underestimates exposure in mountainous regions where climate trajectories traverse dissimilar climates, resulting in high MCE. In contrast, in flat regions velocity is high where MCE is low, as these areas have negligible climatic resistance to movement. Our results suggest that mountainous regions are more climatically isolated than previously reported. PMID:27476545

  16. Glycerol, an underestimated flavor precursor in the Maillard reaction.

    PubMed

    Smarrito-Menozzi, Candice; Matthey-Doret, Walter; Devaud-Goumoens, Stéphanie; Viton, Florian

    2013-10-30

    The objective of the present work was to investigate in depth the role of glycerol in Maillard reactions and its potential to act as an active flavor precursor. Reactions using isotopically labeled compounds (various reducing sugars, proline, and glycerol) unambiguously demonstrated that, in addition to its role of solvent, glycerol actively contributes to the formation of proline-specific compounds in Maillard model systems. Additionally, rhamnose and fucose/proline/glycerol systems generated the 2-propionyl-1(3),4,5,6-tetrahydropyridines, known for their roasty, popcorn aroma. Their formation from such systems is unprecedented. The results presented here have direct implications for flavor generation during thermal processing of foods containing glycerol, which is a ubiquitous food ingredient and an underestimated flavor precursor. PMID:23373461

  17. Quality of life and time to death: have the health gains of preventive interventions been underestimated?

    PubMed

    Gheorghe, Maria; Brouwer, Werner B F; van Baal, Pieter H M

    2015-04-01

    This article explores the implications of the relation between quality of life (QoL) and time to death (TTD) for economic evaluations of preventive interventions. By using health survey data on QoL for the general Dutch population linked to the mortality registry, we quantify the magnitude of this relationship. For addressing specific features of the nonstandard QoL distribution such as boundness, skewness, and heteroscedasticity, we modeled QoL using a generalized additive model for location, scale, and shape (GAMLSS) with a β inflated outcome distribution. Our empirical results indicate that QoL decreases when approaching death, suggesting that there is a strong relationship between TTD and QoL. Predictions of different regression models revealed that ignoring this relationship results in an underestimation of the quality-adjusted life year (QALY) gains for preventive interventions. The underestimation ranged between 3% and 7% and depended on age, the number of years gained from the intervention, and the discount rate used. PMID:25341681

  18. Coronary Abnormalities in Hyper-IgE Recurrent Infection Syndrome: Depiction at Coronary MDCT Angiography

    PubMed Central

    Gharib, Ahmed M.; Pettigrew, Roderic I.; Elagha, Abdalla; Hsu, Amy; Welch, Pam; Holland, Steven M.; Freeman, Alexandra F.

    2014-01-01

    OBJECTIVE Hyper-IgE recurrent infection syndrome (HIES or Job’s syndrome) is a rare disorder affecting the immune system and connective tissues. The purpose of this study is to describe the coronary abnormalities in genetically confirmed HIES patients as depicted by coronary MDCT angiography (MDCTA). CONCLUSION Coronary MDCTA has provided an opportunity for noninvasive evaluation of the coronary arteries in patients with HIES. These coronary abnormalities vary from tortuosity to ectatic dilation and focal aneurysms of the coronary arteries. Such an evaluation has potential value in identifying new aspects of this disease and thereby providing better understanding of the pathophysiology of the disorder. PMID:19933621

  19. Coronary Abnormalities in Hyper-IgE Recurrent Infection Syndrome: Depiction at Coronary MDCT Angiography

    PubMed Central

    Gharib, Ahmed M.; Pettigrew, Roderic I.; Elagha, Abdalla; Hsu, Amy; Welch, Pam; Holland, Steven M.; Freeman, Alexandra F.

    2014-01-01

    OBJECTIVE Hyper-IgE recurrent infection syndrome (HIES or Job’s syndrome) is a rare disorder affecting the immune system and connective tissues. The purpose of this study is to describe the coronary abnormalities in genetically confirmed HIES patients as depicted by coronary MDCT angiography (MDCTA). CONCLUSION Coronary MDCTA has provided an opportunity for noninvasive evaluation of the coronary arteries in patients with HIES. These coronary abnormalities vary from tortuosity to ectatic dilation and focal aneurysms of the coronary arteries. Such an evaluation has potential value in identifying new aspects of this disease and thereby providing better understanding of the pathophysiology of the disorder. PMID:21494893

  20. Underestimating the frequency, strength and cost of antipredator responses with data from GPS collars: an example with wolves and elk

    PubMed Central

    Creel, Scott; Winnie, John A; Christianson, David

    2013-01-01

    Field studies that rely on fixes from GPS-collared predators to identify encounters with prey will often underestimate the frequency and strength of antipredator responses. These underestimation biases have several mechanistic causes. (1) Step bias: The distance between successive GPS fixes can be large, and encounters that occur during these intervals go undetected. This bias will generally be strongest for cursorial hunters that can rapidly cover large distances (e.g., wolves and African wild dogs) and when the interval between GPS fixes is long relative to the duration of a hunt. Step bias is amplified as the path travelled between successive GPS fixes deviates from a straight line. (2) Scatter bias: Only a small fraction of the predators in a population typically carry GPS collars, and prey encounters with uncollared predators go undetected unless a collared group-mate is present. This bias will generally be stronger for fission–fusion hunters (e.g., spotted hyenas, wolves, and lions) than for highly cohesive hunters (e.g., African wild dogs), particularly when their group sizes are large. Step bias and scatter bias both cause underestimation of the frequency of antipredator responses. (3) Strength bias: Observations of prey in the absence of GPS fix from a collared predator will generally include a mixture of cases in which predators were truly absent and cases in which predators were present but not detected, which causes underestimation of the strength of antipredator responses. We quantified these biases with data from wolves and African wild dogs and found that fixes from GPS collars at 3-h intervals underestimated the frequency and strength of antipredator responses by a factor >10. We reexamined the results of a recent study of the nonconsumptive effects of wolves on elk in light of these results and confirmed that predation risk has strong effects on elk dynamics by reducing the pregnancy rate. PMID:24455148

  1. Underestimating the frequency, strength and cost of antipredator responses with data from GPS collars: an example with wolves and elk.

    PubMed

    Creel, Scott; Winnie, John A; Christianson, David

    2013-12-01

    Field studies that rely on fixes from GPS-collared predators to identify encounters with prey will often underestimate the frequency and strength of antipredator responses. These underestimation biases have several mechanistic causes. (1) Step bias: The distance between successive GPS fixes can be large, and encounters that occur during these intervals go undetected. This bias will generally be strongest for cursorial hunters that can rapidly cover large distances (e.g., wolves and African wild dogs) and when the interval between GPS fixes is long relative to the duration of a hunt. Step bias is amplified as the path travelled between successive GPS fixes deviates from a straight line. (2) Scatter bias: Only a small fraction of the predators in a population typically carry GPS collars, and prey encounters with uncollared predators go undetected unless a collared group-mate is present. This bias will generally be stronger for fission-fusion hunters (e.g., spotted hyenas, wolves, and lions) than for highly cohesive hunters (e.g., African wild dogs), particularly when their group sizes are large. Step bias and scatter bias both cause underestimation of the frequency of antipredator responses. (3) Strength bias: Observations of prey in the absence of GPS fix from a collared predator will generally include a mixture of cases in which predators were truly absent and cases in which predators were present but not detected, which causes underestimation of the strength of antipredator responses. We quantified these biases with data from wolves and African wild dogs and found that fixes from GPS collars at 3-h intervals underestimated the frequency and strength of antipredator responses by a factor >10. We reexamined the results of a recent study of the nonconsumptive effects of wolves on elk in light of these results and confirmed that predation risk has strong effects on elk dynamics by reducing the pregnancy rate. PMID:24455148

  2. Numerical Study of Turbulent Laryngeal Jet in the MDCT-based Human Lung Model.

    NASA Astrophysics Data System (ADS)

    Lin, Ching-Long; Tawhai, Merryn H.; McLennan, Geoffrey; Hoffman, Eric A.

    2006-11-01

    The geometry of the human upper respiratory tract is constructed from x-ray-based multidetector computed tomography (MDCT: Sensation 64) images using in house developed segmentation software. The geometry consists of a mouth piece, the mouth, the oropharynx, the larynx, and up to 6 generations of the intra-thoracic airway tree. We applied a custom-developed Characteristic-Galerkin finite element method, which solves the three-dimensional incompressible Navier-Stokes equations, to study the effect of turbulence on air flow structures in the MDCT-based lung model. In order to gather sufficient data for analysis of turbulence statistics, a constant flow rate of about 320 ml/s at the peak inspiratory phase is imposed at the terminal branches to draw air into the upper respiratory tract. The flow rate yields an average speed of about 2 m/s and a Reynolds number of 1,700 in the trachea. The characteristics of mean velocity and turbulent kinetic energy are analyzed. A curved sheet-like high-speed laryngeal jet with high turbulence intensity is formed in the trachea. Some peak frequencies associated with the jet flow are detected. Their association with turbulent coherent structures is examined. The work is sponsored by NIH Grants R01-EB-005823 and R01-HL-064368.

  3. Aortic ostia of the bronchial arteries and tracheal bifurcation: MDCT analysis

    PubMed Central

    Ziyawudong, Julaiti; Kawai, Nobuyuki; Sato, Morio; Ikoma, Akira; Sanda, Hiroki; Takeuchi, Taizo; Minamiguchi, Hiroki; Nakai, Motoki; Tanaka, Takami; Sonomura, Tetsuo

    2012-01-01

    AIM: To explore the anatomical relationships between bronchial artery and tracheal bifurcation using computed tomography angiography (CTA). METHODS: One hundred consecutive patients (84 men, 16 women; aged 46-85 years) who underwent CTA using multi-detector row CT (MDCT) were investigated retrospectively. The distance between sites of bronchial artery ostia and tracheal bifurcation, and dividing directions were explored. The directions of division from the descending aorta were described as on a clock face. RESULTS: We identified ostia of 198 bronchial arteries: 95 right bronchial arteries, 67 left bronchial arteries, 36 common trunk arteries. Of these, 172 (87%) divided from the descending aorta, 25 (13%) from the aortic arch, and 1 (0.5%) from the left subclavian artery. The right, left, and common trunk bronchial arteries divided at -1 to 2 cm from tracheal bifurcation with frequencies of 77% (73/95), 82% (54/66), and 70% (25/36), respectively. The dividing direction of right bronchial arteries from the descending aorta was 9 to 10 o’clock with a frequency of 81% (64/79); that of left and common tract bronchial arteries was 11 to 1 o’clock with frequencies of 70% (43/62) and 77% (24/31), respectively. CONCLUSION: CTA using MDCT provides details of the relation between bronchial artery ostia and tracheal bifurcation. PMID:22328969

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

    PubMed

    Kopp, Felix K; Holzapfel, Konstantin; 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

  5. 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.

  6. 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

  7. 3D MDCT-Based System for Planning Peripheral Bronchoscopic Procedures

    PubMed Central

    Gibbs, Jason D.; Graham, Michael W.; Higgins, William E.

    2009-01-01

    The diagnosis and staging of lung cancer often begins with the assessment of a suspect peripheral chest site. Such suspicious peripheral sites may be solitary pulmonary nodules or other abnormally appearing regions of interest (ROIs). The state-of-the-art process for assessing such peripheral ROIs involves off-line procedure planning using a three-dimensional (3D) multidetector computed tomography (MDCT) chest scan followed by bronchoscopy with an ultrathin bronchoscope. We present an integrated computer-based system for planning peripheral bronchoscopic procedures. The system takes a 3D MDCT chest image as input and performs nearly all operations automatically. The only interaction required by the physician is the selection of ROI locations. The system is computationally efficient and fits smoothly within the clinical work flow. Integrated into the system and described in detail in the paper is a new surface-definition method, which is vital for effective analysis and planning to peripheral sites. Results demonstrate the efficacy of the system and its usage for the live guidance of ultrathin bronchoscopy to the periphery. PMID:19217089

  8. The underestimation of egocentric distance: evidence from frontal matching tasks

    PubMed Central

    Li, Zhi; Phillips, John

    2011-01-01

    There is controversy over the existence, nature, and cause of error in egocentric distance judgments. One proposal is that the systematic biases often found in explicit judgments of egocentric distance along the ground may be related to recently observed biases in the perceived declination of gaze (Durgin & Li, Attention, Perception, & Psychophysics, in press), To measure perceived egocentric distance nonverbally, observers in a field were asked to position themselves so that their distance from one of two experimenters was equal to the frontal distance between the experimenters. Observers placed themselves too far away, consistent with egocentric distance underestimation. A similar experiment was conducted with vertical frontal extents. Both experiments were replicated in panoramic virtual reality. Perceived egocentric distance was quantitatively consistent with angular bias in perceived gaze declination (1.5 gain). Finally, an exocentric distance-matching task was contrasted with a variant of the egocentric matching task. The egocentric matching data approximate a constant compression of perceived egocentric distance with a power function exponent of nearly 1; exocentric matches had an exponent of about 0.67. The divergent pattern between egocentric and exocentric matches suggests that they depend on different visual cues. PMID:21735313

  9. Anemia in Inflammatory Bowel Disease: An Under-Estimated Problem?

    PubMed Central

    Rogler, Gerhard; Vavricka, Stephan

    2015-01-01

    Anemia is one of the most frequent complications and/or extraintestinal manifestations of inflammatory bowel disease (IBD). Iron deficiency is the most important cause of anemia in Crohn’s disease and ulcerative colitis patients. Iron deficiency even without anemia may impact the quality of life of our IBD patients. In the last 10 years, the understanding of the pathology of iron-deficiency anemia and “anemia of chronic diseases” has increased; new diagnostic tools have been developed and new therapeutic strategies have been discussed. Hepcidin has been identified to be a central regulator of iron absorption from the intestine and of iron plasma levels. Hepcidin is regulated by iron deficiency but also as an acute phase protein by pro-inflammatory mediators such as interleukin-6. Innovative diagnostic tools have not been introduced in clinical routine or are not available for routine diagnostics. As iron substitution therapy is easy these days with a preference for intravenous substitution, the impact of differential diagnosis of anemia in IBD patients is underestimated. PMID:25646159

  10. Quantifying Greenland freshwater flux underestimates in climate models

    NASA Astrophysics Data System (ADS)

    Little, Christopher M.; Piecuch, Christopher G.; Chaudhuri, Ayan H.

    2016-05-01

    Key processes regulating the mass balance of the Greenland Ice Sheet (GIS) are not represented in current-generation climate models. Here using output from 19 different climate models forced with a high-end business-as-usual emissions pathway, we compare modeled freshwater fluxes (FWF) to a parameterization based on midtropospheric temperature. By the mid 21st century, parameterized GIS FWF is 478 ± 215 km3 yr-1 larger than modeled—over 3 times the 1992-2011 rate of GIS mass loss. By the late 21st century, ensemble mean parameterized GIS FWF anomalies are comparable to FWF anomalies over the northern North Atlantic Ocean, equivalent to approximately 11 cm of global mean sea level rise. The magnitude and spread of these underestimates underscores the need for assessments of the coupled response of the ocean to increased FWF that recognize: (1) the widely varying freshwater budgets of each model and (2) uncertainty in the relationship between GIS FWF and atmospheric temperature.

  11. The MTT assay underestimates the growth inhibitory effects of interferons.

    PubMed Central

    Jabbar, S. A.; Twentyman, P. R.; Watson, J. V.

    1989-01-01

    The growth inhibitory effects of interferons, IFN-alpha and IFN-gamma on human lung cancer cell lines were studied using both a tetrazolium (MTT) colorimetric assay and direct cell counting. Significant discrepancies between the two assays were observed, the MTT assay consistently underestimating the growth inhibitory effects of the IFNs. There was no direct chemical effect of the IFNs on the tetrazolium reduction process. IFN treated cells showed increased cell size compared with control cells, although there was little or no change in cell cycle distribution. Mitochondrial activity was 30-50% greater in IFN-gamma treated cells (COR-L23) than the controls. Reduced formazan production per cell was observed in medium which had supported cell growth for several days. Differential 'medium conditioning' led to a difference in formazan production per cell between IFN and control cells and this was the major basis of the observed discrepancy. This discrepancy was not due to the differences in the glucose concentrations between these media. However, differences in pH between the media proved to be the major contributory factor of the discrepancy. PMID:2529890

  12. Don't underestimate the power of culture.

    PubMed

    Imes, Susan; Landry, Denise

    2002-01-01

    Integrating a client's health care beliefs into the plan of care is the first step in providing culturally congruent care. Since caring is largely defined within a cultural context, knowing how clients wish to be cared for, and knowing about their culture, is paramount for the nursing profession. Transcultural nursing, a specialized area within nursing, embraces the power of culture. Transcultural nurses recognize and utilize the role of culture in the provision of culturally congruent care. By the year 2060, non-Hispanic whites are projected to comprise about half of the U.S. population (49.4%). In the year 2000, an estimated 12% of registered nurses were from an identified minority group. Therefore, it is not surprising that the culture of nursing in the United States continues to reflect the predominant values of the non-Hispanic white or Anglo-American culture. Ethnocentrism and cultural imposition must be avoided. Three major health belief systems (biomedical, naturalistic, and magico-religious) are presented with emphasis on their influential power with respect to health care practices. Underestimating the power of culture may be harmful to the health of the client. PMID:12616779

  13. Satellite methods underestimate indirect climate forcing by aerosols

    PubMed Central

    Penner, Joyce E.; Xu, Li; Wang, Minghuai

    2011-01-01

    Satellite-based estimates of the aerosol indirect effect (AIE) are consistently smaller than the estimates from global aerosol models, and, partly as a result of these differences, the assessment of this climate forcing includes large uncertainties. Satellite estimates typically use the present-day (PD) relationship between observed cloud drop number concentrations (Nc) and aerosol optical depths (AODs) to determine the preindustrial (PI) values of Nc. These values are then used to determine the PD and PI cloud albedos and, thus, the effect of anthropogenic aerosols on top of the atmosphere radiative fluxes. Here, we use a model with realistic aerosol and cloud processes to show that empirical relationships for ln(Nc) versus ln(AOD) derived from PD results do not represent the atmospheric perturbation caused by the addition of anthropogenic aerosols to the preindustrial atmosphere. As a result, the model estimates based on satellite methods of the AIE are between a factor of 3 to more than a factor of 6 smaller than model estimates based on actual PD and PI values for Nc. Using ln(Nc) versus ln(AI) (Aerosol Index, or the optical depth times angstrom exponent) to estimate preindustrial values for Nc provides estimates for Nc and forcing that are closer to the values predicted by the model. Nevertheless, the AIE using ln(Nc) versus ln(AI) may be substantially incorrect on a regional basis and may underestimate or overestimate the global average forcing by 25 to 35%. PMID:21808047

  14. 3D Volumetric Evaluation of Lipiodol Retention in HCC after Chemoembolization: A Quantitative Comparison between CBCT and MDCT

    PubMed Central

    Wang, Zhijun; Lin, MingDe; Lesage, David; Chen, Rongxin; Chapiro, Julius; Gu, Tara; Tacher, Vania; Duran, Rafael; Geschwind, Jean-François

    2014-01-01

    Rationale and Objectives To evaluate the capability of cone-beam computed tomography (CBCT) acquired immediately after transcatheter arterial chemoembolization (TACE) in determining Lipiodol retention quantitatively and volumetrically when compared to 1-day post-procedure unenhanced MDCT. Materials and methods From June to December, 2012, fifteen patients met the inclusion criteria of unresectable hepatocellular carcinoma (HCC) that was treated with conventional TACE (cTACE), and had intra-procedural CBCT and 1-day post-TACE MDCT. Four patients were excluded because the Lipiodol was diffuse throughout the entire liver or Lipiodol deposition was not clear on both CBCT and MDCT. Eleven patients with a total of 31 target lesions were included in the analysis. A quantitative and 3D software was used to assess complete, localized and diffuse lipiodol deposition. Tumor volume, Lipiodol volume in the tumor, % Lipiodol retention, and Lipiodol enhancement in Hounsfield Unit (HU) were calculated and compared between CBCT and MDCT using two-tailed student’s t-test and Bland-Altman plots. Results The mean value of tumor volume, Lipiodol deposited regions, calculated average % Lipiodol retention, and HU value of CBCT were not significantly different from those of MDCT (tumor volume: 9.37±11.35cm3 vs. 9.34±11.44cm3, P=0.991; Lipiodol volume: 7.84±9.34cm3 vs. 7.84±9.60 cm3, P=0.998; % Lipiodol retention: 89.3%±14.7% vs. 90.2% ± 14.9%, P=0.811; HU value: 307.7±160.1 HU vs. 257.2±120.0 HU, P=0.139). Bland-Altman plots showed only minimal difference and high agreement when comparing CBCT to MDCT. Conclusion CBCT has a similar capability, intraprocedurally, to assess Lipiodol deposition in 3D for patients with HCC treated with cTACE when compared to MDCT. PMID:24507426

  15. Correcting eddy-covariance flux underestimates over a grassland.

    SciTech Connect

    Twine, T. E.; Kustas, W. P.; Norman, J. M.; Cook, D. R.; Houser, P. R.; Meyers, T. P.; Prueger, J. H.; Starks, P. J.; Wesely, M. L.; Environmental Research; Univ. of Wisconsin at Madison; DOE; National Aeronautics and Space Administration; National Oceanic and Atmospheric Administrationoratory

    2000-06-08

    Independent measurements of the major energy balance flux components are not often consistent with the principle of conservation of energy. This is referred to as a lack of closure of the surface energy balance. Most results in the literature have shown the sum of sensible and latent heat fluxes measured by eddy covariance to be less than the difference between net radiation and soil heat fluxes. This under-measurement of sensible and latent heat fluxes by eddy-covariance instruments has occurred in numerous field experiments and among many different manufacturers of instruments. Four eddy-covariance systems consisting of the same models of instruments were set up side-by-side during the Southern Great Plains 1997 Hydrology Experiment and all systems under-measured fluxes by similar amounts. One of these eddy-covariance systems was collocated with three other types of eddy-covariance systems at different sites; all of these systems under-measured the sensible and latent-heat fluxes. The net radiometers and soil heat flux plates used in conjunction with the eddy-covariance systems were calibrated independently and measurements of net radiation and soil heat flux showed little scatter for various sites. The 10% absolute uncertainty in available energy measurements was considerably smaller than the systematic closure problem in the surface energy budget, which varied from 10 to 30%. When available-energy measurement errors are known and modest, eddy-covariance measurements of sensible and latent heat fluxes should be adjusted for closure. Although the preferred method of energy balance closure is to maintain the Bowen-ratio, the method for obtaining closure appears to be less important than assuring that eddy-covariance measurements are consistent with conservation of energy. Based on numerous measurements over a sorghum canopy, carbon dioxide fluxes, which are measured by eddy covariance, are underestimated by the same factor as eddy covariance evaporation

  16. Impact of Aortic Valve Calcification, as Measured by MDCT, on Survival in Patients With Aortic Stenosis

    PubMed Central

    Clavel, Marie-Annick; Pibarot, Philippe; Messika-Zeitoun, David; Capoulade, Romain; Malouf, Joseph; Aggarval, Shivani; Araoz, Phillip A.; Michelena, Hector I.; Cueff, Caroline; Larose, Eric; Miller, Jordan D.; Vahanian, Alec; Enriquez-Sarano, Maurice

    2014-01-01

    BACKGROUND Aortic valve calcification (AVC) load measures lesion severity in aortic stenosis (AS) and is useful for diagnostic purposes. Whether AVC predicts survival after diagnosis, independent of clinical and Doppler echocardiographic AS characteristics, has not been studied. OBJECTIVES This study evaluated the impact of AVC load, absolute and relative to aortic annulus size (AVCdensity), on overall mortality in patients with AS under conservative treatment and without regard to treatment. METHODS In 3 academic centers, we enrolled 794 patients (mean age, 73 ± 12 years; 274 women) diagnosed with AS by Doppler echocardiography who underwent multidetector computed tomography (MDCT) within the same episode of care. Absolute AVC load and AVCdensity (ratio of absolute AVC to cross-sectional area of aortic annulus) were measured, and severe AVC was separately defined in men and women. RESULTS During follow-up, there were 440 aortic valve implantations (AVIs) and 194 deaths (115 under medical treatment). Univariate analysis showed strong association of absolute AVC and AVCdensity with survival (both, p < 0.0001) with a spline curve analysis pattern of threshold and plateau of risk. After adjustment for age, sex, coronary artery disease, diabetes, symptoms, AS severity on hemodynamic assessment, and LV ejection fraction, severe absolute AVC (adjusted hazard ratio [HR]: 1.75; 95% confidence interval [CI]: 1.04 to 2.92; p = 0.03) or severe AVCdensity (adjusted HR: 2.44; 95% CI: 1.37 to 4.37; p = 0.002) independently predicted mortality under medical treatment, with additive model predictive value (all, p ≤ 0.04) and a net reclassification index of 12.5% (p = 0.04). Severe absolute AVC (adjusted HR: 1.71; 95% CI: 1.12 to 2.62; p = 0.01) and severe AVCdensity (adjusted HR: 2.22; 95% CI: 1.40 to 3.52; p = 0.001) also independently predicted overall mortality, even with adjustment for time-dependent AVI. CONCLUSIONS This large-scale, multicenter outcomes study of

  17. Dynamic left ventricular outflow tract obstruction: underestimated cause of hypotension and hemodynamic instability

    PubMed Central

    2014-01-01

    Left ventricular outflow tract obstruction, which is typically associated with hypertrophic cardiomyopathy, is the third most frequent cause of unexplained hypotension. This underestimated problem may temporarily accompany various diseases (it is found in even <1% of patients with no tangible cardiac disease) and clinical situations (hypovolemia, general anesthesia). It is currently assumed that left ventricular outflow tract obstruction is a dynamic phenomenon, the occurrence of which requires the coexistence of predisposing anatomic factors and a physiological condition that induces it. The diagnosis of left ventricular outflow tract obstruction should entail immediate implementation of the therapy to eliminate the factors that can potentially intensify the obstruction. Echocardiography is the basic modality in the diagnosis and treatment of left ventricular outflow tract obstruction. This paper presents four patients in whom the immediate implementation of bedside echocardiography enabled a rapid diagnosis of left ventricular outflow tract obstruction and implementation of proper treatment. PMID:26674265

  18. What Pacific tsunamis tell us about underestimating hazard and risk

    NASA Astrophysics Data System (ADS)

    Goff, J. R.

    2011-12-01

    occurred in prehistory than have occurred in historic time. Larger events have occurred in prehistory than have been modelled in any probabilistic tsunami hazard assessment. This talk presents work that draws together much of the geological, TEK and archaeological evidence for such events and makes one key point - palaeotsunamis have had significant impact upon prehistoric coastal settlements and culture. We are currently underestimating the hazard and this does little to help in our assessment of the risk.

  19. Modelflow underestimates cardiac output in heat-stressed individuals.

    PubMed

    Shibasaki, Manabu; Wilson, Thad E; Bundgaard-Nielsen, Morten; Seifert, Thomas; Secher, Niels H; Crandall, Craig G

    2011-02-01

    An estimation of cardiac output can be obtained from arterial pressure waveforms using the Modelflow method. However, whether the assumptions associated with Modelflow calculations are accurate during whole body heating is unknown. This project tested the hypothesis that cardiac output obtained via Modelflow accurately tracks thermodilution-derived cardiac outputs during whole body heat stress. Acute changes of cardiac output were accomplished via lower-body negative pressure (LBNP) during normothermic and heat-stressed conditions. In nine healthy normotensive subjects, arterial pressure was measured via brachial artery cannulation and the volume-clamp method of the Finometer. Cardiac output was estimated from both pressure waveforms using the Modeflow method. In normothermic conditions, cardiac outputs estimated via Modelflow (arterial cannulation: 6.1 ± 1.0 l/min; Finometer 6.3 ± 1.3 l/min) were similar with cardiac outputs measured by thermodilution (6.4 ± 0.8 l/min). The subsequent reduction in cardiac output during LBNP was also similar among these methods. Whole body heat stress elevated internal temperature from 36.6 ± 0.3 to 37.8 ± 0.4°C and increased cardiac output from 6.4 ± 0.8 to 10.9 ± 2.0 l/min when evaluated with thermodilution (P < 0.001). However, the increase in cardiac output estimated from the Modelflow method for both arterial cannulation (2.3 ± 1.1 l/min) and Finometer (1.5 ± 1.2 l/min) was attenuated compared with thermodilution (4.5 ± 1.4 l/min, both P < 0.01). Finally, the reduction in cardiac output during LBNP while heat stressed was significantly attenuated for both Modelflow methods (cannulation: -1.8 ± 1.2 l/min, Finometer: -1.5 ± 0.9 l/min) compared with thermodilution (-3.8 ± 1.19 l/min). These results demonstrate that the Modelflow method, regardless of Finometer or direct arterial waveforms, underestimates cardiac output during heat stress and during subsequent reductions in cardiac output via LBNP. PMID:21084673

  20. Q fever--still a query and underestimated infectious disease.

    PubMed

    Kovácová, E; Kazár, J

    2002-01-01

    Coxiella burnetii (C.b.) is a strictly intracellular, Gram-negative bacterium. It causes Q fever in humans and animals worldwide. The animal Q fever is sometimes designated "coxiellosis". This infection has many different reservoirs including arthropods, birds and mammals. Domestic animals and pets, are the most frequent source of human infections. Q fever may appear basically in two forms, acute and chronic (persistent). The latter form of Q fever in animals is characteristic by shedding C.b. into the environment during parturition or abortion. Human Q fever results usually from inhalation of contaminated aerosols originating mostly from tissue and body fluids of infected animals. Q fever may appear in humans either in an acute form accompanied mainly by fever (pneumonia, flu-like disease, hepatitis) or in a chronic form (mainly endocarditis). Diagnosis of Q fever is based on isolation of the agent in cell culture, its direct detection, namely by PCR, and serology. Detection of high phase II antibodies titers 1-3 weeks after the onset of symptoms and identification of IgM antibodies are indicative to acute infection. High phase I IgG antibody titers >800 as revealed by microimmunofluorescence offer evidence of chronic C.b. infection. For acute Q fever, a two-weeks-treatment with doxycycline is recommended as the first-line therapy. In the case of Q fever endocarditis a long-term combined antibiotic therapy is necessary to prevent relapses. Application of Q fever vaccines containing or prepared from phase I C.b. corpuscles should be considered at least for professionally exposed groups of the population. Infections caused by C.b. are spread worldwide and may pose serious and often underestimated health problems in human but also in veterinary medicine. Though during the last decades substantial progress in investigation of C.b. has been achieved and many data concerning this pathogen has been accumulated, some questions, namely those related to the pathogenesis of

  1. Acute colonic diverticulitis: an update on clinical classification and management with MDCT correlation.

    PubMed

    Barat, Maxime; Dohan, Anthony; Pautrat, Karine; Boudiaf, Mourad; Dautry, Raphael; Guerrache, Youcef; Pocard, Marc; Hoeffel, Christine; Eveno, Clarisse; Soyer, Philippe

    2016-09-01

    Currently, the most commonly used classification of acute colonic diverticulitis (ACD) is the modified Hinchey classification, which corresponds to a slightly more complex classification by comparison with the original description. This modified classification allows to categorize patients with ACD into four major categories (I, II, III, IV) and two additional subcategories (Ia and Ib), depending on the severity of the disease. Several studies have clearly demonstrated the impact of this classification for determining the best therapeutic approach and predicting perioperative complications for patients who need surgery. This review provides an update on the classification of ACD along with a special emphasis on the corresponding MDCT features of the different categories and subcategories. This modified Hinchey classification should be known by emergency physicians, radiologists, and surgeons in order to improve patient care and management because each category has a specific therapeutic approach. PMID:27138434

  2. 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. PMID:25541332

  3. Multidetector CT in emergency radiology: acute and generalized non-traumatic abdominal pain.

    PubMed

    Paolantonio, Pasquale; Rengo, Marco; Ferrari, Riccardo; Laghi, Andrea

    2016-05-01

    Multidetector CT (MDCT) is an imaging technique that provides otherwise unobtainable information in the diagnostic work-up of patients presenting with acute abdominal pain. A correct working diagnosis depends essentially on understanding the individual patient's clinical data and laboratory findings. In haemodynamically stable patients with acute severe and generalized abdominal pain, MDCT is now the preferred imaging test and gives invaluable diagnostic information, also in unstable patients after stabilization. In this descriptive review, we focus our attention on acute, severe and generalized or undifferentiated non-traumatic abdominal pain. The main differential diagnoses are acute pancreatitis, gastrointestinal perforation, ruptured abdominal aneurysm and acute mesenteric ischaemia. We will provide radiologist readers with a technical guide to optimize MDCT imaging protocols and list the major CT signs essential to reach a correct diagnosis and guide the best treatment. PMID:26689097

  4. Underestimated Sensitivity of Mammalian Cochlear Hair Cells Due to Splay between Stereociliary Columns

    PubMed Central

    Nam, Jong-Hoon; Peng, Anthony W.; Ricci, Anthony J.

    2015-01-01

    Current-displacement (I-X) and the force-displacement (F-X) relationships characterize hair-cell mechano-transduction in the inner ear. A common technique for measuring these relationships is to deliver mechanical stimulations to individual hair bundles with microprobes and measure whole cell transduction currents through patch pipette electrodes at the basolateral membrane. The sensitivity of hair-cell mechano-transduction is determined by two fundamental biophysical properties of the mechano-transduction channel, the stiffness of the putative gating spring and the gating swing, which are derived from the I-X and F-X relationships. Although the hair-cell stereocilia in vivo deflect <100 nm even at high sound pressure levels, often it takes >500 nm of stereocilia displacement to saturate hair-cell mechano-transduction in experiments with individual hair cells in vitro. Despite such discrepancy between in vivo and in vitro data, key biophysical properties of hair-cell mechano-transduction to define the transduction sensitivity have been estimated from in vitro experiments. Using three-dimensional finite-element methods, we modeled an inner hair-cell and an outer hair-cell stereocilia bundle and simulated the effect of probe stimulation. Unlike the natural situation where the tectorial membrane stimulates hair-cell stereocilia evenly, probes deflect stereocilia unevenly. Because of uneven stimulation, 1) the operating range (the 10–90% width of the I-X relationship) increases by a factor of 2–8 depending on probe shapes, 2) the I-X relationship changes from a symmetric to an asymmetric function, and 3) the bundle stiffness is underestimated. Our results indicate that the generally accepted assumption of parallel stimulation leads to an overestimation of the gating swing and underestimation of the gating spring stiffness by an order of magnitude. PMID:26039165

  5. The feasibility of a 64-slice MDCT for detection of the Adamkiewicz artery: comparison of the detection rate of intravenous injection CT angiography using a 64-slice MDCT versus intra-arterial and intravenous injection CT angiography using a 16-slice MDCT.

    PubMed

    Nishii, Tatsuya; Kono, Atsushi K; Negi, Noriyuki; Hashimura, Hiromi; Uotani, Kensuke; Okita, Yutaka; Sugimura, Kazuro

    2013-12-01

    Identification of the Adamkiewicz artery (AKA) using CT angiography (CTA) is crucial in patients with thoracic aortic aneurysm (TAA) or aortic dissection (AD). The purpose of this study was to compare the AKA detection rate of intravenous injection with a 64-slice MDCT (IV64) versus a 16-slice MDCT (IV16) as well as by CTA using intra-arterial injection with a 16-slice MDCT (IA16). A retrospective review of 160 consecutive patients who underwent CTA was performed. There were 108 TAA and 52 AD cases, 105 of whom were examined with IV64, 15 with IV16, and 40 with IA16. The AKA detectability for each imaging method was assessed, and the factors influencing the detectability were analyzed by multivariate analysis. The detection rates for IV64, IV16, and IA16 were 85.7, 60.0, and 80.0 %, respectively, with IV64 being more sensitive than IV16 (P = 0.025). The detection rate for AD patients was 66.7 % with IV64, which was similar to IV16 (57.1 %) and IA16 (66.8 %). On the other hand, the detection rate for TAA patients was 93.3 % with IV64, which was higher than IV16 (62.5 %, P = 0.021) and similar to IA16 (88.0 %). Multivariate analysis demonstrated the independent factors for AKA detectability were TAA versus AD (P = 0.005, Odds ratio = 3.98) and IV64 versus IV16 (P = 0.037, Odds ratio = 4.03). The detection rate was higher for IV64 than for IV16, especially for TAA patients, while the rate was similar between IV64 and invasive IA16. A 64-slice MDCT thus provides a less invasive visualization of the AKA. PMID:24081485

  6. 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

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

    PubMed Central

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

    2009-01-01

    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°–340° in 20° 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

  8. Underestimation of Leptospirosis Incidence in the French West Indies

    PubMed Central

    Cassadou, Sylvie; Rosine, Jacques; Flamand, Claude; Escher, Martina; Ledrans, Martine; Bourhy, Pascale; Picardeau, Mathieu; Quénel, Philippe

    2016-01-01

    Background Leptospirosis is a neglected zoonosis affecting mainly tropical and subtropical regions worldwide, particularly South America and the Caribbean. As in many other countries, under-reporting of cases was suspected in the French West Indies because of inadequate access to diagnostic tests for the general population. Methodology/Principal findings In order to estimate the real incidence of leptospirosis in Guadeloupe and Martinique, a study was performed in 2011 using the three prevailing available biological tests for diagnosis: Microscopic Agglutination Test (MAT), IgM ELISA and PCR. The study investigated inpatients and outpatients and used active case ascertainment from data provided by a general practitioners’ sentinel network. The epidemiology of the disease was also described in terms of severity and demographic characteristics. Leptospirosis incidence was estimated at 69.4 (95%CI 47.6–91.1) and 60.6 (95%CI 36.3–85.0) annual cases per 100 000 inhabitants in Guadeloupe and Martinique, respectively, which was 3 and 4 times higher than previous estimations. Conclusion/Significance Inclusion of PCR and IgM ELISA tests for diagnosis of leptospirosis resulted in improved sensitivity in comparison with MAT alone. Our results highlighted the substantial health burden of the disease in these two territories and the importance of access to appropriate laboratory tests. Based on our results, PCR and IgM ELISA tests have now been included in the list of tests reimbursed by the national system of social security insurance in France. Our results also underline the relevance of implementing an integrated strategy for the surveillance, prevention and control of leptospirosis in the French West Indies. PMID:27128631

  9. Two underestimated threats in food transportation: mould and acceleration

    PubMed Central

    Janssen, S.; Pankoke, I.; Klus, K.; Schmitt, K.; Stephan, U.; Wöllenstein, J.

    2014-01-01

    Two important parameters are often neglected in the monitoring of perishable goods during transport: mould contamination of fresh food and the influence of acceleration or vibration on the quality of a product. We assert the claim that it is necessary to focus research on these two topics in the context of intelligent logistics in this opinion paper. Further, the technical possibilities for future measurement systems are discussed. By measuring taste deviations, we verified the effect on the quality of beer at different vibration frequencies. The practical importance is shown by examining transport routes and market shares. The general feasibility of a mobile mould detection system is established by examining the measurement resolution of semiconductor sensors for mould-related gases. Furthermore, as an alternative solution, we present a concept for a miniaturized and automated culture-medium-based system. Although there is a lack of related research to date, new efforts can make a vital contribution to the reduction of losses in the logistic chains for several products. PMID:24797139

  10. Archaea associated with human surfaces: not to be underestimated.

    PubMed

    Bang, Corinna; Schmitz, Ruth A

    2015-09-01

    Over 40 years ago, Carl Woese and his colleagues discovered the existence of two distinctly different groups of prokaryotes-Bacteria and Archaea. In the meantime, extensive research revealed that several hundred of bacterial species are intensely associated with humans' health and disease. Archaea, originally identified and described to occur mainly in extreme environments, have been shown to be ubiquitous and to appear frequently and in high numbers as part of human microbiota in recent years. Despite the improvement in methodologies leading to increased detection, archaea are often still not considered in many studies focusing on the interdependency between members of the microbiota and components of the human immune system. As a consequence, the knowledge on functional role(s) of archaeal species within the human body is mainly limited to their contribution to nutrient degradation in the intestine, and evidence for immunogenic properties of archaea as part of the human microbiota is generally rare. In this review, the current knowledge of human mucosa-associated archaeal species, their interaction with the human immune system and their potential contribution to humans' health and disease will be discussed. PMID:25907112

  11. Two underestimated threats in food transportation: mould and acceleration.

    PubMed

    Janssen, S; Pankoke, I; Klus, K; Schmitt, K; Stephan, U; Wöllenstein, J

    2014-06-13

    Two important parameters are often neglected in the monitoring of perishable goods during transport: mould contamination of fresh food and the influence of acceleration or vibration on the quality of a product. We assert the claim that it is necessary to focus research on these two topics in the context of intelligent logistics in this opinion paper. Further, the technical possibilities for future measurement systems are discussed. By measuring taste deviations, we verified the effect on the quality of beer at different vibration frequencies. The practical importance is shown by examining transport routes and market shares. The general feasibility of a mobile mould detection system is established by examining the measurement resolution of semiconductor sensors for mould-related gases. Furthermore, as an alternative solution, we present a concept for a miniaturized and automated culture-medium-based system. Although there is a lack of related research to date, new efforts can make a vital contribution to the reduction of losses in the logistic chains for several products. PMID:24797139

  12. Simulating solid lung nodules in MDCT images for CAD evaluation: modeling, validation, and applications

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangwei; Olcott, E.; Raffy, Philippe; Yu, Naichang; Chui, Haili

    2007-03-01

    A new lung nodule simulation model was designed to create and insert synthetic solid lung nodules, with shapes and density similar to real nodules, into normal MDCT chest exams. Nodule shapes were modeled using linearly deformed superquadrics with added randomly generated high dimensional deformations. Nodule density statistics and attenuation profiles were extracted from a group of real nodule samples, by dissecting each real nodule digitally layer by layer from the border to the core. A nodule created with modeled shape and density was inserted into real CT images by creating volume average layers using weighted averaging between nodule density and background density for each voxel. The nodule simulation model was validated both subjectively by human experts and quantitatively by comparing density attenuation profiles of simulated nodules with real nodules. These validation studies demonstrated a high level of similarity between the synthetic nodules and real nodules. This nodule simulation model was used to create objective test databases for use in evaluating a CAD system. The evaluation study showed that the CAD system was accurate in detection and volume measurement for isolated nodules, and also performed relatively well for juxta-vascular nodules. The CAD system also demonstrated stable performances for different dosages.

  13. [Measurement of scatter radiation on MDCT equipment using an OSL dosimeter].

    PubMed

    Tomita, Hironobu; Morozumi, Kunihiko

    2004-11-01

    The recent introduction of multi-detector row computed tomography (MDCT) has made it possible to scan the entire abdomen within approximately 10 sec in procedures such as interventional radiology computed tomography (IVRCT), which are associated with operator exposure. Therefore, anxious patients and patients who are not able to remain still can be examined with an assistant. In the present study, radiation exposure to the assistant was estimated, and the distribution of scattered radiation near the gantry was measured using an optically stimulated luminescence (OSL) dosimeter. Simultaneous measurements were obtained using a direction storage (DIS) dosimeter for reference. The maximum value of 1.47 mSv per examination was obtained at the point closest to the gantry's center (50 cm from the center at a height of 150 cm above the floor) . In addition, scattered radiation decreased as the measurement point was moved further from the gantry's center, falling below the limit of detection (0.1 mSv or less) at 200 cm and at the sides of the gantry. OSL dosimeters are also employed as personal dosimeters, permitting reliable values to be obtained easily. They were found to be an effective tool for the measurement of scattered radiation, as in the present study, helping to provide better understanding of the distribution of scattered radiation within the CT room. PMID:15568007

  14. The underestimated role of olfaction in avian reproduction ?

    PubMed Central

    Balthazart, Jacques; Taziaux, Mélanie

    2009-01-01

    Until the second half of the 20th century, it was broadly accepted that most birds are microsmatic if not anosmic and unable to detect and use olfactory information. Exceptions were eventually conceded for species like procellariiforms, vultures or kiwis that detect their food at least in part based on olfactory signals. During the past 20–30 years, many publications have appeared indicating that this view is definitely erroneous. We briefly review here anatomical, electrophysiological and behavioral data demonstrating that birds in general possess a functional olfactory system and are able to use olfactory information in a variety of ethological contexts, including reproduction. Recent work also indicates that brain activation induced by sexual interactions with a female is significantly affected by olfactory deprivation in Japanese quail. Brain activation was measured via immunocytochemical detection of the protein product of the immediate early gene c-fos. Changes observed concerned two brain areas that play a key role in the control of male sexual behavior, the medial preoptic nucleus and the bed nucleus of the stria terminalis therefore suggesting a potential role of olfaction in the control of reproduction. The widespread idea that birds are anosmic or microsmatic is thus not supported by the available experimental data and presumably originates in our anthropomorphic view that leads us to think that birds do not smell because they have a rigid beak and nostrils and do not obviously sniff. Experimental analysis of this phenomenon is thus warranted and should lead to a significant change in our understanding of avian biology. PMID:18804490

  15. Underestimation of mid-Holocene Arctic warming in PMIP simulations

    NASA Astrophysics Data System (ADS)

    Zhang, Qiong; Muschitiello, Francesco

    2016-04-01

    Due to the orbital forcing, Arctic is warmer during mid-Holocene (~ 6 kyr BP) in summer because the region received more insolation and also warmer in winter because of strong feedbacks, leads to an annual mean temperature warming. Existing proxy reconstructions show that the Arctic can be two degrees warmer than pre-industrial. However, not all the climate models can capture the warming, and the amplitude is about 0.5 degree less than that seen from proxy data. One possible reason is that these simulations did not take into account a fact of 'Green Sahara', where the large area of Sahara region is covered by vegetation instead of desert as it is today. By using a fully coupled climate model EC-Earth with about 100 km resolution, we have run a series of sensitivity experiments by changing the surface type, as well as accompanied change in dust emission over the northern Sahara. The results show that a green sahara not only results in local climate response such as the northward extension and strengthening of African monsoon, but also affect the large scale circulation and corresponding meridional heat transport. The combination of green sahara and reduced dust entails a general strengthening of the mid-latitude Westerlies, results in a change to more positive North Atlantic Oscillation-like conditions, and more heat transport from lower latitudes to high latitudes both in atmosphere and ocean, eventually leads to a shift towards warmer conditions over the North Atlantic and Arctic regions. This mechanism would explain the sign of rapid hydro-climatic perturbations recorded in several reconstructions from high northern latitudes after the termination of the African Humid Period around 5.5 - 5.0 kyr BP, suggesting that these regions are sensitive to changes in Saharan land cover during the present interglacial. This is central in the debate surrounding Arctic climate amplification and future projections for subtropical precipitation changes and related surface type

  16. Field Measurements Indicate Unexpected, Serious Underestimation of Mussel Heart Rates and Thermal Tolerance by Laboratory Studies.

    PubMed

    Tagliarolo, Morgana; McQuaid, Christopher D

    2016-01-01

    Attempts to predict the response of species to long-term environmental change are generally based on extrapolations from laboratory experiments that inevitably simplify the complex interacting effects that occur in the field. We recorded heart rates of two genetic lineages of the brown mussel Perna perna over a full tidal cycle in-situ at two different sites in order to evaluate the cardiac responses of the two genetic lineages present on the South African coast to temperature and the immersion/emersion cycle. "Robomussel" temperature loggers were used to monitor thermal conditions at the two sites over one year. Comparison with live animals showed that robomussels provided a good estimate of mussel body temperatures. A significant difference in estimated body temperatures was observed between the sites and the results showed that, under natural conditions, temperatures regularly approach or exceed the thermal limits of P. perna identified in the laboratory. The two P. perna lineages showed similar tidal and diel patterns of heart rate, with higher cardiac activity during daytime immersion and minimal values during daytime emersion. Comparison of the heart rates measured in the field with data previously measured in the laboratory indicates that laboratory results seriously underestimate heart rate activity, by as much as 75%, especially during immersion. Unexpectedly, field estimates of body temperatures indicated an ability to tolerate temperatures considered lethal on the basis of laboratory measurements. This suggests that the interaction of abiotic conditions in the field does not necessarily raise vulnerability to high temperatures. PMID:26840775

  17. Field Measurements Indicate Unexpected, Serious Underestimation of Mussel Heart Rates and Thermal Tolerance by Laboratory Studies

    PubMed Central

    Tagliarolo, Morgana; McQuaid, Christopher D.

    2016-01-01

    Attempts to predict the response of species to long-term environmental change are generally based on extrapolations from laboratory experiments that inevitably simplify the complex interacting effects that occur in the field. We recorded heart rates of two genetic lineages of the brown mussel Perna perna over a full tidal cycle in-situ at two different sites in order to evaluate the cardiac responses of the two genetic lineages present on the South African coast to temperature and the immersion/emersion cycle. “Robomussel” temperature loggers were used to monitor thermal conditions at the two sites over one year. Comparison with live animals showed that robomussels provided a good estimate of mussel body temperatures. A significant difference in estimated body temperatures was observed between the sites and the results showed that, under natural conditions, temperatures regularly approach or exceed the thermal limits of P. perna identified in the laboratory. The two P. perna lineages showed similar tidal and diel patterns of heart rate, with higher cardiac activity during daytime immersion and minimal values during daytime emersion. Comparison of the heart rates measured in the field with data previously measured in the laboratory indicates that laboratory results seriously underestimate heart rate activity, by as much as 75%, especially during immersion. Unexpectedly, field estimates of body temperatures indicated an ability to tolerate temperatures considered lethal on the basis of laboratory measurements. This suggests that the interaction of abiotic conditions in the field does not necessarily raise vulnerability to high temperatures. PMID:26840775

  18. Underestimating the Toxicological Challenges Associated with the Use of Herbal Medicinal Products in Developing Countries

    PubMed Central

    Neergheen-Bhujun, Vidushi S.

    2013-01-01

    Various reports suggest a high contemporaneous prevalence of herb-drug use in both developed and developing countries. The World Health Organisation indicates that 80% of the Asian and African populations rely on traditional medicine as the primary method for their health care needs. Since time immemorial and despite the beneficial and traditional roles of herbs in different communities, the toxicity and herb-drug interactions that emanate from this practice have led to severe adverse effects and fatalities. As a result of the perception that herbal medicinal products have low risk, consumers usually disregard any association between their use and any adverse reactions hence leading to underreporting of adverse reactions. This is particularly common in developing countries and has led to a paucity of scientific data regarding the toxicity and interactions of locally used traditional herbal medicine. Other factors like general lack of compositional and toxicological information of herbs and poor quality of adverse reaction case reports present hurdles which are highly underestimated by the population in the developing world. This review paper addresses these toxicological challenges and calls for natural health product regulations as well as for protocols and guidance documents on safety and toxicity testing of herbal medicinal products. PMID:24163821

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

    PubMed

    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 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. PMID:23794749

  20. Dynamic real-time 4D cardiac MDCT image display using GPU-accelerated volume rendering.

    PubMed

    Zhang, Qi; Eagleson, Roy; Peters, Terry M

    2009-09-01

    Intraoperative cardiac monitoring, accurate preoperative diagnosis, and surgical planning are important components of minimally-invasive cardiac therapy. Retrospective, electrocardiographically (ECG) gated, multidetector computed tomographical (MDCT), four-dimensional (3D + time), real-time, cardiac image visualization is an important tool for the surgeon in such procedure, particularly if the dynamic volumetric image can be registered to, and fused with the actual patient anatomy. The addition of stereoscopic imaging provides a more intuitive environment by adding binocular vision and depth cues to structures within the beating heart. In this paper, we describe the design and implementation of a comprehensive stereoscopic 4D cardiac image visualization and manipulation platform, based on the opacity density radiation model, which exploits the power of modern graphics processing units (GPUs) in the rendering pipeline. In addition, we present a new algorithm to synchronize the phases of the dynamic heart to clinical ECG signals, and to calculate and compensate for latencies in the visualization pipeline. A dynamic multiresolution display is implemented to enable the interactive selection and emphasis of volume of interest (VOI) within the entire contextual cardiac volume and to enhance performance, and a novel color and opacity adjustment algorithm is designed to increase the uniformity of the rendered multiresolution image of heart. Our system provides a visualization environment superior to noninteractive software-based implementations, but with a rendering speed that is comparable to traditional, but inferior quality, volume rendering approaches based on texture mapping. This retrospective ECG-gated dynamic cardiac display system can provide real-time feedback regarding the suspected pathology, function, and structural defects, as well as anatomical information such as chamber volume and morphology. PMID:19467840

  1. A Numerical Study of Heat and Water Vapor Transfer in MDCT-Based Human Airway Models

    PubMed Central

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

    2014-01-01

    A three-dimensional (3D) thermo-fluid model is developed to study regional distributions of temperature and water vapor in three multi-detector row computed-tomography (MDCT)-basedhuman airwayswith minute ventilations of 6, 15 and 30 L/min. A one-dimensional (1D) model is also solved to provide necessary initial and boundary conditionsforthe 3D model. Both 3D and 1D predicted temperature distributions agree well with available in vivo measurement data. On inspiration, the 3D cold high-speed air stream is split at the bifurcation to form secondary flows, with its cold regions biased toward the inner wall. The cold air flowing along the wall is warmed up more rapidly than the air in the lumen center. The repeated splitting pattern of air streams caused by bifurcations acts as an effective mechanism for rapid heat and mass transfer in 3D. This provides a key difference from the 1D model, where heating relies largely on diffusion in the radial direction, thus significantly affecting gradient-dependent variables, such as energy flux and water loss rate. We then propose the correlations for respective heat and mass transfer in the airways of up to 6 generations: Nu=3.504(ReDaDt)0.277, R = 0.841 and Sh=3.652(ReDaDt)0.268, R = 0.825, where Nu is the Nusselt number, Sh is the Sherwood number, Re is the branch Reynolds number, Da is the airway equivalent diameter, and Dt is the tracheal equivalentdiameter. PMID:25081386

  2. 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.

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

    PubMed Central

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

    2012-01-01

    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. PMID:23794749

  4. Improvement of image quality in MDCT by high-frequency sampling of x-, y- and z-direction

    NASA Astrophysics Data System (ADS)

    Yasuda, Naruomi; Ishikawa, Yoko; Kodera, Yoshie

    2006-03-01

    The multi-detector row computed tomography (MDCT) has dramatically increased speed of scanning, and allows high-resolution imaging compared with the conventional single-detector row CT (SDCT). However, use of the MDCT was making use of three-dimensional (3D) volume scanning and four-dimensional (4D) dynamic scanning increase, and made radiation dose to patients increase simultaneously. In addition, in recent years, lung-cancer screening CT (LSCT) is introduced, and low-dose scanning is strongly required to increase the benefit/risk ratio. In this study, high-frequency volume data sampling (over-sampling) method of x-, y- and z-direction was proposed as technique for reduction of image noise in the MDCT and discussed about reduction of radiation dose and improvement of image quality. In this proposed method, volume data are obtained by over-sampling of x-, y- and z-direction and image is obtained by averaging these data. In x- and y-direction, over-sampling is equivalent to obtaining projection data using large matrix size for same scan-field of view (scan-FOV), and in z-direction, equivalent to using thin slice. Normally, when signal with which noise distribution differs are averaged n-times, signal-to-noise ratio (SNR) will increases by factor of [square root of] n. In this method, each pixel value of the image is obtained from n2 x,yn z pixels by n x,y-times sampling for x- and y-direction, and n z-times sampling for z-direction. In other words, SNR of the image increases [square root of] n2 x,yn z-times. In this high-frequency data sampling method, it is possible to obtain high-quality image as compared with conventional image. Moreover, by applying to noisy image obtained with low-dose scanning, reduction of radiation dose to patients is possible.

  5. Visual vs Fully Automatic Histogram-Based Assessment of Idiopathic Pulmonary Fibrosis (IPF) Progression Using Sequential Multidetector Computed Tomography (MDCT)

    PubMed Central

    Colombi, Davide; Dinkel, Julien; Weinheimer, Oliver; Obermayer, Berenike; Buzan, Teodora; Nabers, Diana; Bauer, Claudia; Oltmanns, Ute; Palmowski, Karin; Herth, Felix; Kauczor, Hans Ulrich; Sverzellati, Nicola

    2015-01-01

    Objectives To describe changes over time in extent of idiopathic pulmonary fibrosis (IPF) at multidetector computed tomography (MDCT) assessed by semi-quantitative visual scores (VSs) and fully automatic histogram-based quantitative evaluation and to test the relationship between these two methods of quantification. Methods Forty IPF patients (median age: 70 y, interquartile: 62-75 years; M:F, 33:7) that underwent 2 MDCT at different time points with a median interval of 13 months (interquartile: 10-17 months) were retrospectively evaluated. In-house software YACTA quantified automatically lung density histogram (10th-90th percentile in 5th percentile steps). Longitudinal changes in VSs and in the percentiles of attenuation histogram were obtained in 20 untreated patients and 20 patients treated with pirfenidone. Pearson correlation analysis was used to test the relationship between VSs and selected percentiles. Results In follow-up MDCT, visual overall extent of parenchymal abnormalities (OE) increased in median by 5 %/year (interquartile: 0 %/y; +11 %/y). Substantial difference was found between treated and untreated patients in HU changes of the 40th and of the 80th percentiles of density histogram. Correlation analysis between VSs and selected percentiles showed higher correlation between the changes (Δ) in OE and Δ 40th percentile (r=0.69; p<0.001) as compared to Δ 80th percentile (r=0.58; p<0.001); closer correlation was found between Δ ground-glass extent and Δ 40th percentile (r=0.66, p<0.001) as compared to Δ 80th percentile (r=0.47, p=0.002), while the Δ reticulations correlated better with the Δ 80th percentile (r=0.56, p<0.001) in comparison to Δ 40th percentile (r=0.43, p=0.003). Conclusions There is a relevant and fully automatically measurable difference at MDCT in VSs and in histogram analysis at one year follow-up of IPF patients, whether treated or untreated: Δ 40th percentile might reflect the change in overall extent of lung

  6. 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. PMID:24173609

  7. The preoperative intraocular pressure level predicts the amount of underestimated intraocular pressure after LASIK for myopia

    PubMed Central

    Chihara, E; Takahashi, H; Okazaki, K; Park, M; Tanito, M

    2005-01-01

    Aims: To evaluate the statistical significance of the parameters that affect underestimation of intraocular pressure (IOP) after laser in situ keratomileusis (LASIK) for myopia. Methods: In this prospective case series study, patient age, axial length, preoperative corneal curvature, preoperative central corneal thickness (CCT), preoperative IOP, and ablation depth were studied to determine whether they affect the underestimation of IOP in the right eyes of 100 consecutive patients who underwent LASIK. Results: The preoperative IOP was the most important parameter for an amount of underestimated Goldmann applanation tonometric IOP (GAT) and non-contact tonometric IOP (ncIOP) at 1 month (r = 0.654, p<0.0001, R2 = 0.427, and r = 0.694, p<0.0001, R2 = 0.481, respectively) and 3 months (r = 0.637, p<0.0001, R2 = 0.406, and r = 0.726, p<0.0001, R2 = 0.527, respectively). Patient age was statistically significant for underestimating the GAT at 1 month, and both the ablation depth and CCT were statistically significant parameters for underestimating the ncIOP at 1 month and at 3 months by stepwise multiple regression analysis (F>4.000). However, these parameters had small bivariate correlation coefficients, and were considered as minor parameters. Conclusion: Preoperative IOP is the most important parameter that affects an underestimation of IOP after LASIK for myopia. Eyes with a higher true IOP have a larger underestimation of the IOP after LASIK for myopia. From these results, the importance of the modulus of elasticity on IOP measurements was discussed. PMID:15665345

  8. Seabird bycatch in pelagic longline fisheries is grossly underestimated when using only haul data.

    PubMed

    Brothers, Nigel; Duckworth, Alan R; Safina, Carl; Gilman, Eric L

    2010-01-01

    Hundreds of thousands of seabirds are killed each year as bycatch in longline fisheries. Seabirds are predominantly caught during line setting but bycatch is generally recorded during line hauling, many hours after birds are caught. Bird loss during this interval may lead to inaccurate bycatch information. In this 15 year study, seabird bycatch was recorded during both line setting and line hauling from four fishing regions: Indian Ocean, Southern Ocean, Coral Sea and central Pacific Ocean. Over 43,000 albatrosses, petrels and skuas representing over 25 species were counted during line setting of which almost 6,000 seabirds attempted to take the bait. Bait-taking interactions were placed into one of four categories. (i) The majority (57%) of bait-taking attempts were "unsuccessful" involving seabirds that did not take the bait nor get caught or hooked. (ii) One-third of attempts were "successful" with seabirds removing the bait while not getting caught. (iii) One-hundred and seventy-six seabirds (3% of attempts) were observed being "caught" during line setting, with three albatross species - Laysan (Phoebastria immutabilis), black-footed (P. nigripes) and black-browed (Thalassarche melanophrys)- dominating this category. However, of these, only 85 (48%) seabird carcasses were retrieved during line hauling. Most caught seabirds were hooked through the bill. (iv) The remainder of seabird-bait interactions (7%) was not clearly observed, but likely involved more "caught" seabirds. Bait taking attempts and percentage outcome (e.g. successful, caught) varied between seabird species and was not always related to species abundance around fishing vessels. Using only haul data to calculate seabird bycatch grossly underestimates actual bycatch levels, with the level of seabird bycatch from pelagic longline fishing possibly double what was previously thought. PMID:20824163

  9. Misery Has More Company Than People Think: Underestimating the Prevalence of Others’ Negative Emotions

    PubMed Central

    Jordan, Alexander H.; Monin, Benoît; Dweck, Carol S.; Lovett, Benjamin J.; John, Oliver P.; Gross, James J.

    2014-01-01

    Four studies document underestimations of the prevalence of others’ negative emotions, and suggest causes and correlates of these erroneous perceptions. In Study 1A, participants reported that their negative emotions were more private or hidden than their positive emotions; in Study 1B, participants underestimated the peer prevalence of common negative, but not positive, experiences described in Study 1A. In Study 2, people underestimated negative emotions and overestimated positive emotions even for well-known peers, and this effect was partially mediated by the degree to which those peers reported suppression of negative (vs. positive) emotions. Study 3 showed that lower estimations of the prevalence of negative emotional experiences predicted greater loneliness and rumination and lower life satisfaction, and that higher estimations for positive emotional experiences predicted lower life satisfaction. Taken together, these studies suggest that people may think they are more alone in their emotional difficulties than they really are. PMID:21177878

  10. 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.

  11. 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

  12. Calorie Underestimation When Buying High-Calorie Beverages in Fast-Food Contexts.

    PubMed

    Franckle, Rebecca L; Block, Jason P; Roberto, Christina A

    2016-07-01

    We asked 1877 adults and 1178 adolescents visiting 89 fast-food restaurants in New England in 2010 and 2011 to estimate calories purchased. Calorie underestimation was greater among those purchasing a high-calorie beverage than among those who did not (adults: 324 ±698 vs 102 ±591 calories; adolescents: 360 ±602 vs 198 ±509 calories). This difference remained significant for adults but not adolescents after adjusting for total calories purchased. Purchasing high-calorie beverages may uniquely contribute to calorie underestimation among adults. PMID:27196648

  13. Underestimating the Duration of Future Events: Memory Incorrectly Used or Memory Bias?

    ERIC Educational Resources Information Center

    Roy, Michael M.; Christenfeld, Nicholas J. S.; McKenzie, Craig R. M.

    2005-01-01

    People frequently underestimate how long it will take them to complete a task. The prevailing view is that during the prediction process, people incorrectly use their memories of how long similar tasks have taken in the past because they take an overly optimistic outlook. A variety of evidence is reviewed in this article that points to a…

  14. Preferred child body size and parental underestimation of child weight in Mexican-American families

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: To determine whether parents who prefer a heavier child would underestimate their child's weight more than those who prefer a leaner child. Methods: Participants were Mexican-American families (312 mothers, 173 fathers, and 312 children ages 8-10) who were interviewed and had height and w...

  15. 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

  16. Tick-borne encephalitis (TBE): an underestimated risk…still: report of the 14th annual meeting of the International Scientific Working Group on Tick-Borne Encephalitis (ISW-TBE).

    PubMed

    Kunze, Ursula

    2012-06-01

    Today, the risk of getting tick-borne encephalitis (TBE) is still underestimated in many parts of Europe and worldwide. Therefore, the 14th meeting of the International Scientific Working Group on Tick-Borne Encephalitis (ISW-TBE) - a group of neurologists, general practitioners, clinicians, travel physicians, virologists, pediatricians, and epidemiologists - was held under the title "Tick-borne encephalitis: an underestimated risk…still". Among the discussed issues were: TBE, an underestimated risk in children, a case report in two Dutch travelers, the very emotional report of a tick victim, an overview of the epidemiological situation, investigations to detect new TBE cases in Italy, TBE virus (TBEV) strains circulation in Northern Europe, TBE Program of the European Centre for Disease Prevention and Control (ECDC), efforts to increase the TBE vaccination rate in the Czech Republic, positioning statement of the World Health Organization (WHO), and TBE in dogs. To answer the question raised above: Yes, the risk of getting TBE is underestimated in children and adults, because awareness is still too low. It is still underestimated in several areas of Europe, where, for a lack of human cases, TBEV is thought to be absent. It is underestimated in travelers, because they still do not know enough about the risk, and diagnostic awareness in non-endemic countries is still low. PMID:22765977

  17. Correlating MDCT Liver Injury Grade and Clinical Outcome in Patients Without Significant Extra-hepatic Injury.

    PubMed

    Kumar, Ravi; Kumar, Atin; Baliyan, Vinit; Gamanagatti, Shivanand; Bhalla, Ashu Seith; Sharma, Raju; Gupta, Amit; Kumar, Subodh; Misra, M C

    2016-08-01

    The aim of the study was to correlate multi-detector computed tomography (MDCT) grading with clinical severity and outcome in liver trauma patients without significant extrahepatic injury. Over a period of 2 years (2011-2013), all patients showing evidence of liver injury on contrast-enhanced CT (CECT) abdomen and without significant extrahepatic trauma were prospectively included in the study. Correlation between the CT injury grade and outcome in terms of mortality, duration of ICU/hospital stay, fluid and blood requirements, need for intervention and complications were assessed. The significance of the difference in mortality, duration of ICU/hospital stay, fluid requirement and blood requirements among the patients with various injury grades was assessed by Kruskal-Wallis test. The significance of the difference in need for intervention and complications among the patients with various injury grades was assessed by Fisher's exact test. A total of 198 patients were found to have evidence of hepatic injury on CECT. Out of 198 patients, 117 had insignificant extrahepatic trauma. The overall mean age for these 117 patients was 25.74 ± 15.53 (age range 2-84 years). Death rates according to AAST grades were 0 % in grades II and III, 6.89 % in grade IV and 9.09 % in grade V (p = 0.053). The mean ICU and total hospital stay for grade II was 1.32 and 5.91 days, for grade III was 1.76 and 8.48, for grade IV was 2.86 and 10.31 days and for grade V was 6.54 and 12 days, respectively (p = 0.0001 for ICU, p = 0.0003 for total stay). Mean input and fluid deficit according to various grades were 8634/2607 ml for grade II, 9535/2555 ml for grade III, 15,549/6242 ml for grade IV and 19,958/8280 ml for grade V (p value input-0.0016, output-input (fluid deficit)-0.0001). Average unit of RBC and sum of the blood products transfused were 1.73 and 2.26 for grade II, 2.18 and 2.72 for grade III, 3.03 and 6.27 for grade IV, 6.85 and 38.12 for grade V

  18. Uncinate Process Variations and Their Relationship with Ostiomeatal Complex: A Pictorial Essay of Multidedector Computed Tomography (MDCT) Findings.

    PubMed

    Güngör, Gülay; Okur, Nazan; Okur, Erdoğan

    2016-01-01

    The ostiomeatal complex (OMC) is a key area for the drainage and ventilation of the paranasal sinuses. Stenosis created by inflammation and anatomic variations in this region causes an ideal ground for parasanal sinus infections, by preventing the drainage and ventilation of the sinuses. In today's diagnostics of paranasal sinus infections, the role of evaluation of OMC anatomical variations and soft tissue pathology has increased.. Knowing the anatomical details is important in terms of directing both medical and surgical treatment. The uncinate process (UP) constitutes the most important structure of the ostiomeatal complex, playing a role in mucociliary activity. UP variations can cause mucociliary drainage and ventilation problems, causing complications during surgery. Therefore, knowing and identifying their appearances in multidetector computed tomography (MDCT), the most frequently used radiological imaging method for these variations, becomes a very important consideration. PMID:27158282

  19. Uncinate Process Variations and Their Relationship with Ostiomeatal Complex: A Pictorial Essay of Multidedector Computed Tomography (MDCT) Findings

    PubMed Central

    Güngör, Gülay; Okur, Nazan; Okur, Erdoğan

    2016-01-01

    Summary The ostiomeatal complex (OMC) is a key area for the drainage and ventilation of the paranasal sinuses. Stenosis created by inflammation and anatomic variations in this region causes an ideal ground for parasanal sinus infections, by preventing the drainage and ventilation of the sinuses. In today’s diagnostics of paranasal sinus infections, the role of evaluation of OMC anatomical variations and soft tissue pathology has increased.. Knowing the anatomical details is important in terms of directing both medical and surgical treatment. The uncinate process (UP) constitutes the most important structure of the ostiomeatal complex, playing a role in mucociliary activity. UP variations can cause mucociliary drainage and ventilation problems, causing complications during surgery. Therefore, knowing and identifying their appearances in multidetector computed tomography (MDCT), the most frequently used radiological imaging method for these variations, becomes a very important consideration. PMID:27158282

  20. Evidence for link between modelled trends in Antarctic sea ice and underestimated westerly wind changes.

    PubMed

    Purich, Ariaan; Cai, Wenju; England, Matthew H; Cowan, Tim

    2016-01-01

    Despite global warming, total Antarctic sea ice coverage increased over 1979-2013. However, the majority of Coupled Model Intercomparison Project phase 5 models simulate a decline. Mechanisms causing this discrepancy have so far remained elusive. Here we show that weaker trends in the intensification of the Southern Hemisphere westerly wind jet simulated by the models may contribute to this disparity. During austral summer, a strengthened jet leads to increased upwelling of cooler subsurface water and strengthened equatorward transport, conducive to increased sea ice. As the majority of models underestimate summer jet trends, this cooling process is underestimated compared with observations and is insufficient to offset warming in the models. Through the sea ice-albedo feedback, models produce a high-latitude surface ocean warming and sea ice decline, contrasting the observed net cooling and sea ice increase. A realistic simulation of observed wind changes may be crucial for reproducing the recent observed sea ice increase. PMID:26842498

  1. The Effect of Swelling Ratio on the Coulter Underestimation of Hydrogel Microsphere Diameters

    PubMed Central

    Pellegrini, Michael; Cherukupalli, Abhimanyu; Medini, Michael; Falkowski, Ron

    2015-01-01

    It has been demonstrated that the diameters of porous particles are underestimated by Coulter measurements. This phenomenon has also been observed in hydrogel particles, but not characterized. Since the Coulter principle uses the displacement of electrolyte to determine particle size, electrolyte contained within the swelled hydrogel microparticles results in an underestimate of actual particle diameters. The increased use of hydrogel microspheres in biomedical applications has led to the increased application of the Coulter principle to evaluate the size distribution of microparticles. A relationship between the swelling ratio of the particles and their reported Coulter diameters will permit calculation of the actual diameters of these particles. Using polyethylene glycol diacrylate hydrogel microspheres, we determined a correction factor that relates the polymer swelling ratio and the reported Coulter diameters to their actual size. PMID:26414785

  2. Evidence for link between modelled trends in Antarctic sea ice and underestimated westerly wind changes

    PubMed Central

    Purich, Ariaan; Cai, Wenju; England, Matthew H.; Cowan, Tim

    2016-01-01

    Despite global warming, total Antarctic sea ice coverage increased over 1979–2013. However, the majority of Coupled Model Intercomparison Project phase 5 models simulate a decline. Mechanisms causing this discrepancy have so far remained elusive. Here we show that weaker trends in the intensification of the Southern Hemisphere westerly wind jet simulated by the models may contribute to this disparity. During austral summer, a strengthened jet leads to increased upwelling of cooler subsurface water and strengthened equatorward transport, conducive to increased sea ice. As the majority of models underestimate summer jet trends, this cooling process is underestimated compared with observations and is insufficient to offset warming in the models. Through the sea ice-albedo feedback, models produce a high-latitude surface ocean warming and sea ice decline, contrasting the observed net cooling and sea ice increase. A realistic simulation of observed wind changes may be crucial for reproducing the recent observed sea ice increase. PMID:26842498

  3. Do seasonal-to-decadal climate predictions underestimate the predictability of the real world?

    PubMed Central

    Eade, Rosie; Smith, Doug; Scaife, Adam; Wallace, Emily; Dunstone, Nick; Hermanson, Leon; Robinson, Niall

    2014-01-01

    Seasonal-to-decadal predictions are inevitably uncertain, depending on the size of the predictable signal relative to unpredictable chaos. Uncertainties can be accounted for using ensemble techniques, permitting quantitative probabilistic forecasts. In a perfect system, each ensemble member would represent a potential realization of the true evolution of the climate system, and the predictable components in models and reality would be equal. However, we show that the predictable component is sometimes lower in models than observations, especially for seasonal forecasts of the North Atlantic Oscillation and multiyear forecasts of North Atlantic temperature and pressure. In these cases the forecasts are underconfident, with each ensemble member containing too much noise. Consequently, most deterministic and probabilistic measures underestimate potential skill and idealized model experiments underestimate predictability. However, skilful and reliable predictions may be achieved using a large ensemble to reduce noise and adjusting the forecast variance through a postprocessing technique proposed here. PMID:25821271

  4. Evidence for link between modelled trends in Antarctic sea ice and underestimated westerly wind changes

    NASA Astrophysics Data System (ADS)

    Purich, Ariaan; Cai, Wenju; England, Matthew H.; Cowan, Tim

    2016-02-01

    Despite global warming, total Antarctic sea ice coverage increased over 1979-2013. However, the majority of Coupled Model Intercomparison Project phase 5 models simulate a decline. Mechanisms causing this discrepancy have so far remained elusive. Here we show that weaker trends in the intensification of the Southern Hemisphere westerly wind jet simulated by the models may contribute to this disparity. During austral summer, a strengthened jet leads to increased upwelling of cooler subsurface water and strengthened equatorward transport, conducive to increased sea ice. As the majority of models underestimate summer jet trends, this cooling process is underestimated compared with observations and is insufficient to offset warming in the models. Through the sea ice-albedo feedback, models produce a high-latitude surface ocean warming and sea ice decline, contrasting the observed net cooling and sea ice increase. A realistic simulation of observed wind changes may be crucial for reproducing the recent observed sea ice increase.

  5. Preferred Child Body Size and Parental Underestimation of Child Weight in Mexican-American Families.

    PubMed

    Pasch, Lauri A; Penilla, Carlos; Tschann, Jeanne M; Martinez, Suzanna M; Deardorff, Julianna; de Groat, Cynthia L; Gregorich, Steven E; Flores, Elena; Butte, Nancy F; Greenspan, Louise C

    2016-09-01

    Objective To determine whether parents who prefer a heavier child would underestimate their child's weight more than those who prefer a leaner child. Methods Participants were Mexican-American families (312 mothers, 173 fathers, and 312 children ages 8-10) who were interviewed and had height and weight measurements. Parents reported their preferred child body size and their perceptions of their child's weight. Parents' underestimation of their child's weight was calculated as the standardized difference between parent's perception of their child's weight and the child's body mass index (BMI) z-score. Demographic factors and parental BMI were also assessed. Results Although 50 % of children were overweight or obese, only 11 % of mothers and 10 % of fathers perceived their children as being somewhat or very overweight. Multiple regressions controlling for covariates (parental BMI and child age) showed that parents who preferred a heavier child body size underestimated their children's weight more, compared to those who preferred a leaner child (β for mothers = .13, p < .03; β for fathers = .17, p < .03). Conclusions for Practice Parents who preferred a heavier child body size underestimated their child's weight to a greater degree than parents who preferred a leaner child. Attempts by pediatricians to correct parents' misperceptions about child weight may damage rapport and ultimately fail if the misperception is actually a reflection of parents' preferences, which may not be readily amenable to change. Future research should address optimal methods of communication about child overweight which take into account parent preferences. PMID:27016351

  6. Hearing in slow-motion: Humans underestimate the speed of moving sounds

    PubMed Central

    Senna, Irene; Parise, Cesare V.; Ernst, Marc O.

    2015-01-01

    Perception can often be described as a statistically optimal inference process whereby noisy and incomplete sensory evidence is combined with prior knowledge about natural scene statistics. Previous evidence has shown that humans tend to underestimate the speed of unreliable moving visual stimuli. This finding has been interpreted in terms of a Bayesian prior favoring low speed, given that in natural visual scenes objects are mostly stationary or slowly-moving. Here we investigated whether an analogous tendency to underestimate speed also occurs in audition: even if the statistics of the visual environment seem to favor low speed, the statistics of the stimuli reaching the individual senses may differ across modalities, hence potentially leading to different priors. Here we observed a systematic bias for underestimating the speed of unreliable moving sounds. This finding suggests the existence of a slow-motion prior in audition, analogous to the one previously found in vision. The nervous system might encode the overall statistics of the world, rather than the specific properties of the signals reaching the individual senses. PMID:26370720

  7. "People underestimate the value of persistence for creative performance": Correction to Lucas and Nordgren (2015).

    PubMed

    2016-04-01

    Reports an error in "People underestimate the value of persistence for creative performance" by Brian J. Lucas and Loran F. Nordgren (Journal of Personality and Social Psychology, 2015[Aug], Vol 109[2], 232-243). In the article, there are misaligned headers and incorrect means and standard deviations for the first six columns in Table 2 due to a production error. The corrected table is present in the erratum. (The following abstract of the original article appeared in record 2015-31619-002.) Across 7 studies, we investigated the prediction that people underestimate the value of persistence for creative performance. Across a range of creative tasks, people consistently underestimated how productive they would be while persisting (Studies 1-3). Study 3 found that the subjectively experienced difficulty, or disfluency, of creative thought accounted for persistence undervaluation. Alternative explanations based on idea quality (Studies 1-2B) and goal setting (Study 4) were considered and ruled out and domain knowledge was explored as a boundary condition (Study 5). In Study 6, the disfluency of creative thought reduced people's willingness to invest in an opportunity to persist, resulting in lower financial performance. This research demonstrates that persistence is a critical determinant of creative performance and that people may undervalue and underutilize persistence in everyday creative problem solving. (PsycINFO Database Record PMID:27078509

  8. the Underestimation of Isorene in Houston during the Texas 2013 DISCOVER-AQ Campaign

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Diao, L.; Czader, B.; Li, X.; Estes, M. J.

    2014-12-01

    This study applies principal component analysis to aircraft data from the Texas 2013 DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field campaign to characterize isoprene sources over Houston during September 2013. The biogenic isoprene signature appears in the third principal component and anthropogenic signals in the following two. Evaluations of the Community Multiscale Air Quality (CMAQ) model simulations of isoprene with airborne measurements are more accurate for suburban areas than for industrial areas. This study also compares model outputs to eight surface automated gas chromatograph (Auto-GC) measurements near the Houston ship channel industrial area during the nighttime and shows that modeled anthropogenic isoprene is underestimated by a factor of 10.60. This study employs a new simulation with a modified anthropogenic emissions inventory (constraining using the ratios of observed values versus simulated ones) that yields closer isoprene predictions at night with a reduction in the mean bias by 56.93%, implying that model-estimated isoprene emissions from the 2008 National Emission Inventory are underestimated in the city of Houston and that other climate models or chemistry and transport models using the same emissions inventory might also be underestimated in other Houston-like areas in the United States.

  9. Sap flow is Underestimated by Thermal Dissipation Sensors due to Alterations of Wood Anatomy

    NASA Astrophysics Data System (ADS)

    Marañón-Jiménez, S.; Wiedemann, A.; van den Bulcke, J.; Cuntz, M.; Rebmann, C.; Steppe, K.

    2014-12-01

    The thermal dissipation technique (TD) is one of the most commonly adopted methods for sap flow measurements. However, underestimations of up to 60% of the tree transpiration have been reported with this technique, although the causes are not certainly known. The insertion of TD sensors within the stems causes damage of the wood tissue and subsequent healing reactions, changing wood anatomy and likely the sap flow path. However, the anatomical changes in response to the insertion of sap flow sensors and the effects on the measured flow have not been assessed yet. In this study, we investigate the alteration of vessel anatomy on wounds formed around TD sensors. Our main objectives were to elucidate the anatomical causes of sap flow underestimation for ring-porous and diffuse-porous species, and relate these changes to sap flow underestimations. Successive sets of TD probes were installed in early, mid and end of the growing season in Fagus sylvatica (diffuse-porous) and Quercus petraea (ring-porous) trees. They were logged after the growing season and additional sets of sensors were installed in the logged stems with presumably no healing reaction. The wood tissue surrounding each sensor was then excised and analysed by X-ray computed microtomography (X-ray micro CT). This technique allowed the quantification of vessel anatomical characteristics and the reconstruction of the 3-D internal microstructure of the xylem vessels so that extension and shape of the altered area could be determined. Gels and tyloses clogged the conductive vessels around the sensors in both beech and oak. The extension of the affected area was larger for beech although these anatomical changes led to similar sap flow underestimations in both species. The higher vessel size in oak may explain this result and, therefore, larger sap flow underestimation per area of affected conductive tissue. The wound healing reaction likely occurred within the first weeks after sensor installation, which

  10. 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

  11. Pulmonary 64-MDCT angiography with 50 mL of iodinated contrast material in an unselected patient population: a feasible protocol*

    PubMed Central

    Trad, Henrique Simão; Boasquevisque, Gustavo Santos; Giacometti, Tiago Rangon; Trad, Catherine Yang; Zoghbi Neto, Orlando Salomão; Trad, Clovis Simão

    2016-01-01

    Objective To propose a protocol for pulmonary angiography using 64-slice multidetector computed tomography (64-MDCT) with 50 mL of iodinated contrast material, in an unselected patient population, as well as to evaluate vascular enhancement and image quality. Materials and Methods We evaluated 29 patients (22-86 years of age). The body mass index ranged from 19.0 kg/m2 to 41.8 kg/m2. Patients underwent pulmonary CT angiography in a 64-MDCT scanner, receiving 50 mL of iodinated contrast material via venous access at a rate of 4.5 mL/s. Bolus tracking was applied in the superior vena cava. Two experienced radiologists assessed image quality and vascular enhancement. Results The mean density was 382 Hounsfield units (HU) for the pulmonary trunk; 379 and 377 HU for the right and left main pulmonary arteries, respectively; and 346 and 364 HU for the right and left inferior pulmonary arteries, respectively. In all patients, subsegmental arteries were analyzed. There were streak artifacts from contrast material in the superior vena cava in all patients. However, those artifacts did not impair the image analysis. Conclusion Our findings suggest that pulmonary angiography using 64-MDCT with 50 mL of iodinated contrast can produce high quality images in unselected patient populations. PMID:27141128

  12. Underestimation of the Maximal Capacity of the Mitochondrial Electron Transport System in Oligomycin-Treated Cells

    PubMed Central

    Ruas, Juliana S.; Siqueira-Santos, Edilene S.; Amigo, Ignacio; Rodrigues-Silva, Erika; Kowaltowski, Alicia J.; Castilho, Roger F.

    2016-01-01

    The maximal capacity of the mitochondrial electron transport system (ETS) in intact cells is frequently estimated by promoting protonophore-induced maximal oxygen consumption preceded by inhibition of oxidative phosphorylation by oligomycin. In the present study, human glioma (T98G and U-87MG) and prostate cancer (PC-3) cells were titrated with different concentrations of the protonophore CCCP to induce maximal oxygen consumption rate (OCR) within respirometers in a conventional growth medium. The results demonstrate that the presence of oligomycin or its A-isomer leads to underestimation of maximal ETS capacity. In the presence of oligomycin, the spare respiratory capacity (SRC), i.e., the difference between the maximal and basal cellular OCR, was underestimated by 25 to 45%. The inhibitory effect of oligomycin on SRC was more pronounced in T98G cells and was observed in both suspended and attached cells. Underestimation of SRC also occurred when oxidative phosphorylation was fully inhibited by the ATP synthase inhibitor citreoviridin. Further experiments indicated that oligomycin cannot be replaced by the adenine nucleotide translocase inhibitors bongkrekic acid or carboxyatractyloside because, although these compounds have effects in permeabilized cells, they do not inhibit oxidative phosphorylation in intact cells. We replaced CCCP by FCCP, another potent protonophore and similar results were observed. Lower maximal OCR and SRC values were obtained with the weaker protonophore 2,4-dinitrophenol, and these parameters were not affected by the presence of oligomycin. In permeabilized cells or isolated brain mitochondria incubated with respiratory substrates, only a minor inhibitory effect of oligomycin on CCCP-induced maximal OCR was observed. We conclude that unless a previously validated protocol is employed, maximal ETS capacity in intact cells should be estimated without oligomycin. The inhibitory effect of an ATP synthase blocker on potent protonophore

  13. Underestimation of the Maximal Capacity of the Mitochondrial Electron Transport System in Oligomycin-Treated Cells.

    PubMed

    Ruas, Juliana S; Siqueira-Santos, Edilene S; Amigo, Ignacio; Rodrigues-Silva, Erika; Kowaltowski, Alicia J; Castilho, Roger F

    2016-01-01

    The maximal capacity of the mitochondrial electron transport system (ETS) in intact cells is frequently estimated by promoting protonophore-induced maximal oxygen consumption preceded by inhibition of oxidative phosphorylation by oligomycin. In the present study, human glioma (T98G and U-87MG) and prostate cancer (PC-3) cells were titrated with different concentrations of the protonophore CCCP to induce maximal oxygen consumption rate (OCR) within respirometers in a conventional growth medium. The results demonstrate that the presence of oligomycin or its A-isomer leads to underestimation of maximal ETS capacity. In the presence of oligomycin, the spare respiratory capacity (SRC), i.e., the difference between the maximal and basal cellular OCR, was underestimated by 25 to 45%. The inhibitory effect of oligomycin on SRC was more pronounced in T98G cells and was observed in both suspended and attached cells. Underestimation of SRC also occurred when oxidative phosphorylation was fully inhibited by the ATP synthase inhibitor citreoviridin. Further experiments indicated that oligomycin cannot be replaced by the adenine nucleotide translocase inhibitors bongkrekic acid or carboxyatractyloside because, although these compounds have effects in permeabilized cells, they do not inhibit oxidative phosphorylation in intact cells. We replaced CCCP by FCCP, another potent protonophore and similar results were observed. Lower maximal OCR and SRC values were obtained with the weaker protonophore 2,4-dinitrophenol, and these parameters were not affected by the presence of oligomycin. In permeabilized cells or isolated brain mitochondria incubated with respiratory substrates, only a minor inhibitory effect of oligomycin on CCCP-induced maximal OCR was observed. We conclude that unless a previously validated protocol is employed, maximal ETS capacity in intact cells should be estimated without oligomycin. The inhibitory effect of an ATP synthase blocker on potent protonophore

  14. Underestimation of oxygen deficiency hazard through use of linearized temperature profiles

    SciTech Connect

    Kerby, J.

    1989-06-15

    The failure mode analysis for any cryogenic system includes the effects of a large liquid spill due to vessel rupture or overfilling. The Oxygen Deficiency Hazard (ODH) analysis for this event is a strong function of the estimated heat flux entering the spilled liquid. A common method for estimating the heat flux is to treat the surface on which the liquid spills as a semi-infinite solid. This note addresses the effect of linearizing the temperature profile in this form of analysis, and shows it to cause the calculated flux to be underestimated by more than a factor of two. 3 refs., 2 figs.

  15. Transducer Shadowing Explains Observed Underestimates in Vertical Wind Velocity from Non-orthogonal Sonic Anemometers

    NASA Astrophysics Data System (ADS)

    Frank, J. M.; Massman, W. J.; Swiatek, E.; Zimmerman, H.; Ewers, B. E.

    2014-12-01

    Sonic anemometry is fundamental to all eddy-covariance studies of surface energy and ecosystem carbon and water balance. While recent studies have shown that some anemometers underestimate vertical wind, we hypothesize that this is caused by the lack of transducer shadowing correction in non-orthogonal models. We tested this in an experiment comparing three sonic anemometer designs: orthogonal (O), non-orthogonal (NO), and quasi-orthogonal (QO); using four models: K-probe (O) and A-probe (NO) (Applied Technologies, Inc.) and CSAT3 (NO) and CSAT3V (QO) (Campbell Scientific, Inc.). For each of a 12-week experiment at the GLEES AmeriFlux site, five instruments from a pool of twelve (three of each model) were randomly selected and located around a control (CSAT3); mid-week all but the control were re-mounted horizontally. We used Bayesian analysis to test differences between models in half-hour standard deviations (σu, σv, σw, and σT), turbulent kinetic energy (TKE), and the ratio between vertical/horizontal TKE (VHTKE). The K-probe experiences horizontal transducer shadowing which is effectively corrected using an established wind-tunnel derived algorithm. We constructed shadow correction algorithms for the NO/QO anemometers by applying the K-probe function to each non-orthogonal transducer pair (SC1) as well as a stronger correction of twice the magnitude (SC2). While the partitioning of VHTKE was higher in O than NO/QO anemometers, the application of SC1 explained 45-60% of this discrepancy while SC2 overcorrected it. During the horizontal manipulation changes in the NO/QO were moderate in σu (4-8% decrease), very strong in σv (9-11% decrease), and minimal in σw (-3 to 4% change) while only σu measurements changed (3% decrease) with the K-probe. These changes were predicted by both shadow correction algorithms, with SC2 better explaining the data. This confirms our hypothesis while eliminating others that attribute the underestimate to a systematic bias in

  16. 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

  17. Predictive equations underestimate resting energy expenditure in female adolescents with phenylketonuria

    PubMed Central

    Quirk, Meghan E.; Schmotzer, Brian J.; Schmotzer, Brian J.; Singh, Rani H.

    2010-01-01

    Resting energy expenditure (REE) is often used to estimate total energy needs. The Schofield equation based on weight and height has been reported to underestimate REE in female children with phenylketonuria (PKU). The objective of this observational, cross-sectional study was to evaluate the agreement of measured REE with predicted REE for female adolescents with PKU. A total of 36 females (aged 11.5-18.7 years) with PKU attending Emory University’s Metabolic Camp (June 2002 – June 2008) underwent indirect calorimetry. Measured REE was compared to six predictive equations using paired Student’s t-tests, regression-based analysis, and assessment of clinical accuracy. The differences between measured and predicted REE were modeled against clinical parameters to determine to if a relationship existed. All six selected equations significantly under predicted measured REE (P< 0.005). The Schofield equation based on weight had the greatest level of agreement, with the lowest mean prediction bias (144 kcal) and highest concordance correlation coefficient (0.626). However, the Schofield equation based on weight lacked clinical accuracy, predicting measured REE within ±10% in only 14 of 36 participants. Clinical parameters were not associated with bias for any of the equations. Predictive equations underestimated measured REE in this group of female adolescents with PKU. Currently, there is no accurate and precise alternative for indirect calorimetry in this population. PMID:20497783

  18. Underestimated risks of recurrent long-range ash dispersal from northern Pacific Arc volcanoes

    PubMed Central

    Bourne, A. J.; Abbott, P. M.; Albert, P. G.; Cook, E.; Pearce, N. J. G.; Ponomareva, V.; Svensson, A.; Davies, S. M.

    2016-01-01

    Widespread ash dispersal poses a significant natural hazard to society, particularly in relation to disruption to aviation. Assessing the extent of the threat of far-travelled ash clouds on flight paths is substantially hindered by an incomplete volcanic history and an underestimation of the potential reach of distant eruptive centres. The risk of extensive ash clouds to aviation is thus poorly quantified. New evidence is presented of explosive Late Pleistocene eruptions in the Pacific Arc, currently undocumented in the proximal geological record, which dispersed ash up to 8000 km from source. Twelve microscopic ash deposits or cryptotephra, invisible to the naked eye, discovered within Greenland ice-cores, and ranging in age between 11.1 and 83.7 ka b2k, are compositionally matched to northern Pacific Arc sources including Japan, Kamchatka, Cascades and Alaska. Only two cryptotephra deposits are correlated to known high-magnitude eruptions (Towada-H, Japan, ca 15 ka BP and Mount St Helens Set M, ca 28 ka BP). For the remaining 10 deposits, there is no evidence of age- and compositionally-equivalent eruptive events in regional volcanic stratigraphies. This highlights the inherent problem of under-reporting eruptions and the dangers of underestimating the long-term risk of widespread ash dispersal for trans-Pacific and trans-Atlantic flight routes. PMID:27445233

  19. A Large Underestimate of Formic Acid from Tropical Fires: Constraints from Space-Borne Measurements.

    PubMed

    Chaliyakunnel, S; Millet, D B; Wells, K C; Cady-Pereira, K E; Shephard, M W

    2016-06-01

    Formic acid (HCOOH) is one of the most abundant carboxylic acids and a dominant source of atmospheric acidity. Recent work indicates a major gap in the HCOOH budget, with atmospheric concentrations much larger than expected from known sources. Here, we employ recent space-based observations from the Tropospheric Emission Spectrometer with the GEOS-Chem atmospheric model to better quantify the HCOOH source from biomass burning, and assess whether fire emissions can help close the large budget gap for this species. The space-based data reveal a severe model HCOOH underestimate most prominent over tropical burning regions, suggesting a major missing source of organic acids from fires. We develop an approach for inferring the fractional fire contribution to ambient HCOOH and find, based on measurements over Africa, that pyrogenic HCOOH:CO enhancement ratios are much higher than expected from direct emissions alone, revealing substantial secondary organic acid production in fire plumes. Current models strongly underestimate (by 10 ± 5 times) the total primary and secondary HCOOH source from African fires. If a 10-fold bias were to extend to fires in other regions, biomass burning could produce 14 Tg/a of HCOOH in the tropics or 16 Tg/a worldwide. However, even such an increase would only represent 15-20% of the total required HCOOH source, implying the existence of other larger missing sources. PMID:27149080

  20. Quantifying the underestimation of relative risks from genome-wide association studies.

    PubMed

    Spencer, Chris; Hechter, Eliana; Vukcevic, Damjan; Donnelly, Peter

    2011-03-01

    Genome-wide association studies (GWAS) have identified hundreds of associated loci across many common diseases. Most risk variants identified by GWAS will merely be tags for as-yet-unknown causal variants. It is therefore possible that identification of the causal variant, by fine mapping, will identify alleles with larger effects on genetic risk than those currently estimated from GWAS replication studies. We show that under plausible assumptions, whilst the majority of the per-allele relative risks (RR) estimated from GWAS data will be close to the true risk at the causal variant, some could be considerable underestimates. For example, for an estimated RR in the range 1.2-1.3, there is approximately a 38% chance that it exceeds 1.4 and a 10% chance that it is over 2. We show how these probabilities can vary depending on the true effects associated with low-frequency variants and on the minor allele frequency (MAF) of the most associated SNP. We investigate the consequences of the underestimation of effect sizes for predictions of an individual's disease risk and interpret our results for the design of fine mapping experiments. Although these effects mean that the amount of heritability explained by known GWAS loci is expected to be larger than current projections, this increase is likely to explain a relatively small amount of the so-called "missing" heritability. PMID:21437273

  1. Cancer stem cells are underestimated by standard experimental methods in clear cell renal cell carcinoma.

    PubMed

    Gedye, Craig; Sirskyj, Danylo; Lobo, Nazleen C; Meens, Jalna; Hyatt, Elzbieta; Robinette, Michael; Fleshner, Neil; Hamilton, Robert J; Kulkarni, Girish; Zlotta, Alexandre; Evans, Andrew; Finelli, Antonio; Jewett, Michael A S; Ailles, Laurie E

    2016-01-01

    Rare cancer stem cells (CSC) are proposed to be responsible for tumour propagation and re-initiation and are functionally defined by identifying tumour-initiating cells (TICs) using the xenotransplantation limiting dilution assay (LDA). While TICs in clear cell renal cell carcinoma (ccRCC) appeared rare in NOD/SCID/IL2Rγ(-/-) (NSG) mice, xenografts formed more efficiently from small tumour fragments, indicating the LDA underestimated ccRCC TIC frequency. Mechanistic interrogation of the LDA identified multiple steps that influence ccRCC TIC quantitation. For example, tissue disaggregation destroys most ccRCC cells, common assays significantly overestimate tumour cell viability, and microenvironmental supplementation with human extracellular factors or pharmacological inhibition of anoikis increase clonogenicity and tumourigenicity of ccRCC cell lines and primary tumour cells. Identification of these previously uncharacterized concerns that cumulatively lead to substantial underestimation of TICs in ccRCC provides a framework for development of more accurate TIC assays in the future, both for this disease and for other cancers. PMID:27121191

  2. Underestimated risks of recurrent long-range ash dispersal from northern Pacific Arc volcanoes.

    PubMed

    Bourne, A J; Abbott, P M; Albert, P G; Cook, E; Pearce, N J G; Ponomareva, V; Svensson, A; Davies, S M

    2016-01-01

    Widespread ash dispersal poses a significant natural hazard to society, particularly in relation to disruption to aviation. Assessing the extent of the threat of far-travelled ash clouds on flight paths is substantially hindered by an incomplete volcanic history and an underestimation of the potential reach of distant eruptive centres. The risk of extensive ash clouds to aviation is thus poorly quantified. New evidence is presented of explosive Late Pleistocene eruptions in the Pacific Arc, currently undocumented in the proximal geological record, which dispersed ash up to 8000 km from source. Twelve microscopic ash deposits or cryptotephra, invisible to the naked eye, discovered within Greenland ice-cores, and ranging in age between 11.1 and 83.7 ka b2k, are compositionally matched to northern Pacific Arc sources including Japan, Kamchatka, Cascades and Alaska. Only two cryptotephra deposits are correlated to known high-magnitude eruptions (Towada-H, Japan, ca 15 ka BP and Mount St Helens Set M, ca 28 ka BP). For the remaining 10 deposits, there is no evidence of age- and compositionally-equivalent eruptive events in regional volcanic stratigraphies. This highlights the inherent problem of under-reporting eruptions and the dangers of underestimating the long-term risk of widespread ash dispersal for trans-Pacific and trans-Atlantic flight routes. PMID:27445233

  3. Drastic underestimation of amphipod biodiversity in the endangered Irano-Anatolian and Caucasus biodiversity hotspots.

    PubMed

    Katouzian, Ahmad-Reza; Sari, Alireza; Macher, Jan N; Weiss, Martina; Saboori, Alireza; Leese, Florian; Weigand, Alexander M

    2016-01-01

    Biodiversity hotspots are centers of biological diversity and particularly threatened by anthropogenic activities. Their true magnitude of species diversity and endemism, however, is still largely unknown as species diversity is traditionally assessed using morphological descriptions only, thereby ignoring cryptic species. This directly limits evidence-based monitoring and management strategies. Here we used molecular species delimitation methods to quantify cryptic diversity of the montane amphipods in the Irano-Anatolian and Caucasus biodiversity hotspots. Amphipods are ecosystem engineers in rivers and lakes. Species diversity was assessed by analysing two genetic markers (mitochondrial COI and nuclear 28S rDNA), compared with morphological assignments. Our results unambiguously demonstrate that species diversity and endemism is dramatically underestimated, with 42 genetically identified freshwater species in only five reported morphospecies. Over 90% of the newly recovered species cluster inside Gammarus komareki and G. lacustris; 69% of the recovered species comprise narrow range endemics. Amphipod biodiversity is drastically underestimated for the studied regions. Thus, the risk of biodiversity loss is significantly greater than currently inferred as most endangered species remain unrecognized and/or are only found locally. Integrative application of genetic assessments in monitoring programs will help to understand the true magnitude of biodiversity and accurately evaluate its threat status. PMID:26928527

  4. Drastic underestimation of amphipod biodiversity in the endangered Irano-Anatolian and Caucasus biodiversity hotspots

    PubMed Central

    Katouzian, Ahmad-Reza; Sari, Alireza; Macher, Jan N.; Weiss, Martina; Saboori, Alireza; Leese, Florian; Weigand, Alexander M.

    2016-01-01

    Biodiversity hotspots are centers of biological diversity and particularly threatened by anthropogenic activities. Their true magnitude of species diversity and endemism, however, is still largely unknown as species diversity is traditionally assessed using morphological descriptions only, thereby ignoring cryptic species. This directly limits evidence-based monitoring and management strategies. Here we used molecular species delimitation methods to quantify cryptic diversity of the montane amphipods in the Irano-Anatolian and Caucasus biodiversity hotspots. Amphipods are ecosystem engineers in rivers and lakes. Species diversity was assessed by analysing two genetic markers (mitochondrial COI and nuclear 28S rDNA), compared with morphological assignments. Our results unambiguously demonstrate that species diversity and endemism is dramatically underestimated, with 42 genetically identified freshwater species in only five reported morphospecies. Over 90% of the newly recovered species cluster inside Gammarus komareki and G. lacustris; 69% of the recovered species comprise narrow range endemics. Amphipod biodiversity is drastically underestimated for the studied regions. Thus, the risk of biodiversity loss is significantly greater than currently inferred as most endangered species remain unrecognized and/or are only found locally. Integrative application of genetic assessments in monitoring programs will help to understand the true magnitude of biodiversity and accurately evaluate its threat status. PMID:26928527

  5. A large underestimate of the pyrogenic source of formic acid inferred from space-borne measurements.

    NASA Astrophysics Data System (ADS)

    Chaliyakunnel, S.; Millet, D. B.; Wells, K. C.; Cady-Pereira, K.; Shephard, M.

    2015-12-01

    Formic acid (HCOOH) is one of the most abundant carboxylic acids in the atmosphere, and a dominant source of acidity in the global troposphere. Recent work has revealed a major gap in our present understanding of the atmospheric formic acid budget, with observed concentrations much larger than can be reconciled with current estimates of its sources. In this work, we employ new space-based observations from the Tropospheric Emission Spectrometer (TES) satellite instrument with the GEOS-Chem chemical transport model to better quantify the source of atmospheric formic acid from biomass burning, and assess the degree to which this source can help close the large budget gap for this species. The space-based formic acid data reveal a severe model underestimate for HCOOH that is most prominent over tropical biomass burning regions, indicating a major missing source of organic acids from fires. Based on two independent methods for inferring the fractional contribution of fires to the measured HCOOH abundance, we find that the pyrogenic HCOOH:CO enhancement ratio measured by TES (including direct emissions plus secondary production) is 5-10 times higher than current estimates of the direct emission ratio, providing evidence of substantial secondary production of HCOOH in fire plumes. We further show that current models significantly underestimate (by a factor of 2-6) the total primary and secondary source of HCOOH from tropical fires.

  6. Underestimated risks of recurrent long-range ash dispersal from northern Pacific Arc volcanoes

    NASA Astrophysics Data System (ADS)

    Bourne, A. J.; Abbott, P. M.; Albert, P. G.; Cook, E.; Pearce, N. J. G.; Ponomareva, V.; Svensson, A.; Davies, S. M.

    2016-07-01

    Widespread ash dispersal poses a significant natural hazard to society, particularly in relation to disruption to aviation. Assessing the extent of the threat of far-travelled ash clouds on flight paths is substantially hindered by an incomplete volcanic history and an underestimation of the potential reach of distant eruptive centres. The risk of extensive ash clouds to aviation is thus poorly quantified. New evidence is presented of explosive Late Pleistocene eruptions in the Pacific Arc, currently undocumented in the proximal geological record, which dispersed ash up to 8000 km from source. Twelve microscopic ash deposits or cryptotephra, invisible to the naked eye, discovered within Greenland ice-cores, and ranging in age between 11.1 and 83.7 ka b2k, are compositionally matched to northern Pacific Arc sources including Japan, Kamchatka, Cascades and Alaska. Only two cryptotephra deposits are correlated to known high-magnitude eruptions (Towada-H, Japan, ca 15 ka BP and Mount St Helens Set M, ca 28 ka BP). For the remaining 10 deposits, there is no evidence of age- and compositionally-equivalent eruptive events in regional volcanic stratigraphies. This highlights the inherent problem of under-reporting eruptions and the dangers of underestimating the long-term risk of widespread ash dispersal for trans-Pacific and trans-Atlantic flight routes.

  7. Cancer stem cells are underestimated by standard experimental methods in clear cell renal cell carcinoma

    PubMed Central

    Gedye, Craig; Sirskyj, Danylo; Lobo, Nazleen C.; Meens, Jalna; Hyatt, Elzbieta; Robinette, Michael; Fleshner, Neil; Hamilton, Robert J; Kulkarni, Girish; Zlotta, Alexandre; Evans, Andrew; Finelli, Antonio; Jewett, Michael A. S.; Ailles, Laurie E.

    2016-01-01

    Rare cancer stem cells (CSC) are proposed to be responsible for tumour propagation and re-initiation and are functionally defined by identifying tumour-initiating cells (TICs) using the xenotransplantation limiting dilution assay (LDA). While TICs in clear cell renal cell carcinoma (ccRCC) appeared rare in NOD/SCID/IL2Rγ−/− (NSG) mice, xenografts formed more efficiently from small tumour fragments, indicating the LDA underestimated ccRCC TIC frequency. Mechanistic interrogation of the LDA identified multiple steps that influence ccRCC TIC quantitation. For example, tissue disaggregation destroys most ccRCC cells, common assays significantly overestimate tumour cell viability, and microenvironmental supplementation with human extracellular factors or pharmacological inhibition of anoikis increase clonogenicity and tumourigenicity of ccRCC cell lines and primary tumour cells. Identification of these previously uncharacterized concerns that cumulatively lead to substantial underestimation of TICs in ccRCC provides a framework for development of more accurate TIC assays in the future, both for this disease and for other cancers. PMID:27121191

  8. Climate reconstructions of the NH mean temperature: Can underestimation of trends and variability be avoided?

    NASA Astrophysics Data System (ADS)

    Christiansen, Bo

    2010-05-01

    Knowledge about the climate in the period before instrumental records are available is based on climate proxies obtained from tree-rings, sediments, ice-cores etc. Reconstructing the climate from such proxies is therefore necessary for studies of climate variability and for placing recent climate change into a longer term perspective. More than a decade ago pioneering attempts at using a multi-proxy dataset to reconstruct the Northern Hemisphere (NH) mean temperature resulted in the much published "hockey-stick"; a NH mean temperature that did not vary much before the rapid increase in the last century. Subsequent reconstructions show some differences but the overall "hockey-stick" structure seems to be a persistent feature However, there has been an increasing awareness of the fact that the applied reconstruction methods underestimate the low-frequency variability and trends. The recognition of the inadequacies of the reconstruction methods has to a large degree originated from pseudo-proxy studies, i.e., from long climate model experiments where artificial proxies have been generated and reconstructions based on these have been compared to the known model climate. It has also been found that reconstructions contain a large element of stochasticity which is revealed as broad distributions of skills. This means that it is very difficult to draw conclusions from a single or a few realizations. Climate reconstruction methods are based on variants of linear regression models relating temperatures and proxies. In this contribution we review some of the theory of linear regression and error-in-variables models to identify the sources of the underestimation of variability. Based on the gained insight we formulate a reconstruction method supposed to minimize this underestimation. The method is tested by applying it to an ensemble of surrogate temperature fields based on two climate simulations covering the last 500 and 1000 years. Compared to the RegEM TTLS method and a

  9. Does verbatim sentence recall underestimate the language competence of near-native speakers?

    PubMed Central

    Schweppe, Judith; Barth, Sandra; Ketzer-Nöltge, Almut; Rummer, Ralf

    2015-01-01

    Verbatim sentence recall is widely used to test the language competence of native and non-native speakers since it involves comprehension and production of connected speech. However, we assume that, to maintain surface information, sentence recall relies particularly on attentional resources, which differentially affects native and non-native speakers. Since even in near-natives language processing is less automatized than in native speakers, processing a sentence in a foreign language plus retaining its surface may result in a cognitive overload. We contrasted sentence recall performance of German native speakers with that of highly proficient non-natives. Non-natives recalled the sentences significantly poorer than the natives, but performed equally well on a cloze test. This implies that sentence recall underestimates the language competence of good non-native speakers in mixed groups with native speakers. The findings also suggest that theories of sentence recall need to consider both its linguistic and its attentional aspects. PMID:25698996

  10. Systematic Underestimation of Earthquake Magnitudes from Large Intracontinental Reverse Faults: Historical Ruptures Break Across Segment Boundaries

    NASA Technical Reports Server (NTRS)

    Rubin, C. M.

    1996-01-01

    Because most large-magnitude earthquakes along reverse faults have such irregular and complicated rupture patterns, reverse-fault segments defined on the basis of geometry alone may not be very useful for estimating sizes of future seismic sources. Most modern large ruptures of historical earthquakes generated by intracontinental reverse faults have involved geometrically complex rupture patterns. Ruptures across surficial discontinuities and complexities such as stepovers and cross-faults are common. Specifically, segment boundaries defined on the basis of discontinuities in surficial fault traces, pronounced changes in the geomorphology along strike, or the intersection of active faults commonly have not proven to be major impediments to rupture. Assuming that the seismic rupture will initiate and terminate at adjacent major geometric irregularities will commonly lead to underestimation of magnitudes of future large earthquakes.

  11. Yellow jackets may be an underestimated component of an ant-seed mutualism

    USGS Publications Warehouse

    Bale, M.T.; Zettler, J.A.; Robinson, B.A.; Spira, T.P.; Allen, C.R.

    2003-01-01

    Yellow jackets (Hymenoptera: Vespidae) are attracted to the typically ant-dispersed seeds of trilliums and will take seeds from ants in the genus Aphaenogaster. To determine if yellow jacket, Vespula maculifrons (Buysson), presence interferes with seed foraging by ants, we presented seeds of Trillium discolor Wray to three species (A. texana carolinensis Wheeler, Formica schaufussi Mayr, and Solenopsis invicta Buren) of seed-carrying ants in areas where vespids were present or excluded. We found that interspecific aggression between yellow jackets and ants is species specific. Vespid presence decreased average foraging time and increased foraging efficiency of two of the three ant species studied, a situation that might reflect competition for a limited food source. We also found that yellow jackets removed more seeds than ants, suggestive that vespids are important, albeit underestimated, components of ant-seed mutualisms.

  12. Hemoglobin precipitation by polyethylene glycols leads to underestimation of membrane pore sizes.

    PubMed

    Quijano, Jairo C; Lemeshko, Victor V

    2008-12-01

    The size of pores formed in the plasma membrane by various substances is frequently determined using polyethylene glycols as osmotic protectants. In this work, we have found that the size of pores formed by saponin in the red blood cell membrane determined by hemolysis versus molecular weight of polyethylene glycol was different to that estimated by light dispersion of cell suspensions. After complete swelling of cells induced by saponin in semiisotonic salt media containing 150 mOsm PEG-4000 or PEG-3000, a significant increase in the light absorbance at 640 nm was developed resulting from the formation of hemoglobin precipitates. Easily sedimenting aggregates were also formed when the supernatant of lysed cells was added to the equiosmotic solutions of polyethylene glycols with molecular weight higher than 1000. We suggest that the real size of large pores could be underestimated due to the phenomenon of hemoglobin precipitation by polyethylene glycols. PMID:18692020

  13. Terrestrial pesticide exposure of amphibians: An underestimated cause of global decline?

    PubMed Central

    Brühl, Carsten A.; Schmidt, Thomas; Pieper, Silvia; Alscher, Annika

    2013-01-01

    Amphibians, a class of animals in global decline, are present in agricultural landscapes characterized by agrochemical inputs. Effects of pesticides on terrestrial life stages of amphibians such as juvenile and adult frogs, toads and newts are little understood and a specific risk assessment for pesticide exposure, mandatory for other vertebrate groups, is currently not conducted. We studied the effects of seven pesticide products on juvenile European common frogs (Rana temporaria) in an agricultural overspray scenario. Mortality ranged from 100% after one hour to 40% after seven days at the recommended label rate of currently registered products. The demonstrated toxicity is alarming and a large-scale negative effect of terrestrial pesticide exposure on amphibian populations seems likely. Terrestrial pesticide exposure might be underestimated as a driver of their decline calling for more attention in conservation efforts and the risk assessment procedures in place do not protect this vanishing animal group. PMID:23350038

  14. Light obscuration measurements of highly viscous solutions: sample pressurization overcomes underestimation of subvisible particle counts.

    PubMed

    Weinbuch, Daniel; Jiskoot, Wim; Hawe, Andrea

    2014-09-01

    Light obscuration (LO) is the current standard technique for subvisible particle analysis in the quality control of parenterally administered drugs, including therapeutic proteins. Some of those, however, exhibit high viscosities due to high protein concentrations, which can lead to false results by LO measurements. In this study, we show that elevated sample viscosities, from about 9 cP, lead to an underestimation of subvisible particle concentrations, which is easily overlooked when considering reported data alone. We evaluated a solution to this problem, which is the application of sample pressurization during analysis. The results show that this is an elegant way to restore the reliability of LO analysis of highly viscous products without the necessity of additional sample preparation. PMID:24934297

  15. Virus mutation frequencies can be greatly underestimated by monoclonal antibody neutralization of virions.

    PubMed Central

    Holland, J J; de la Torre, J C; Steinhauer, D A; Clarke, D; Duarte, E; Domingo, E

    1989-01-01

    Monoclonal antibody-resistant mutants have been widely used to estimate virus mutation frequencies. We demonstrate that standard virion neutralization inevitably underestimates monoclonal antibody-resistant mutant genome frequencies of vesicular stomatitis virus, due to phenotypic masking-mixing when wild-type (wt) virions are present in thousandsfold greater numbers. We show that incorporation of antibody into the plaque overlay medium (after virus penetration at 37 degrees C) can provide accurate estimates of genome frequencies of neutral monoclonal antibody-resistant mutant viruses in wt clones. By using this method, we have observed two adjacent G----A base transition frequencies in the I3 epitope to be of the order of 10(-4) in a wt glycine codon. This appears to be slightly lower than the frequencies observed at other sites for total (viable and nonviable) virus genomes when using a direct sequence approach. Images PMID:2479770

  16. Runners greatly underestimate sweat losses before and after a 1-hr summer run.

    PubMed

    O'Neal, Eric K; Davis, Brett A; Thigpen, Lauren K; Caufield, Christina R; Horton, Anthony D; McIntosh, Joyce R

    2012-10-01

    The purpose of this study was to determine how accurately runners estimate their sweat losses. Male (n = 19) and female (n = 20) runners (41 ± 10 yr, VO2max 57 ± 9 ml · kg(-1) · min(-1) from the southeastern U.S. completed an ~1-hr run during late summer on a challenging outdoor road course (wet bulb globe temperature 24.1 ± 1.5 °C). Runs began at ~6:45 a.m. or p.m. Before and after running, participants filled race-aid-station paper cups with a volume of fluid they felt would be equivalent to their sweat losses. Total sweat losses and losses by percent body weight differed (p < .01) between men (1,797 ± 449 ml, 2.3% ± 0.6%) and women (1,155 ± 258 ml, 1.9% ± 0.4%). Postrun estimates (738 ± 470 ml) were lower (p < .001) than sweat losses (1,468 ± 484 ml), equaling underestimations of 50% ± 23%, with no differences in estimation accuracy by percentage between genders. Runners who reported measuring changes in pre- and postrun weight to assess sweat losses within the previous month (n = 9, -54% ± 18%) were no more accurate (p = .55) than runners who had not (n = 30, -48% ± 24%). These results suggest that inadequate fluid intake during runs or between runs may stem from underestimations of sweat losses and that runners who do assess sweat-loss changes may be making sweat-loss calculation errors or do not accurately translate changes in body weight to physical volumes of water. PMID:23011653

  17. Parenting Practices, Parents’ Underestimation of Daughters’ Risks and Alcohol and Sexual Behaviors of Urban Girls

    PubMed Central

    O’Donnell, Lydia; Stueve, Ann; Duran, Richard; Myint-U, Athi; Agronick, Gail; San Doval, Alexi; Wilson-Simmons, Renée

    2008-01-01

    Purpose In urban economically distressed communities, high rates of early sexual initiation combined with alcohol use place adolescent girls at risk of myriad negative health consequences. This paper reports on extent to which parents of young teens underestimate both the risks their daughters are exposed to and the considerable influence they have over their children’s decisions and behaviors. Methods Surveys were conducted with over 700 6th grade girls and their parents recruited from 7 New York City schools serving low-income families. Bivariate and multivariate analyses examined relationships among parents’ practices and perceptions of daughters’ risks, girls’ reports of parenting, and outcomes of girls’ alcohol use, media and peer conduct, and heterosexual romantic and social behaviors that typically precede sexual intercourse. Results 22% of girls reported drinking in the past year, but only 4 parents thought daughters had used alcohol. About 5% of parents thought daughters had hugged and kissed a boy for a long time or hung out with older boys; 38% of girls reported these behaviors. Parents’ underestimation of risk was correlated with lower reports of positive parenting practices by daughters. In multivariate analyses, girls’ reports of parental oversight, rules, and disapproval of risk are associated with all three behavioral outcomes. Adult reports of parenting practices are associated with girls’ conduct and heterosexual behaviors, but not alcohol use. Conclusion Creating greater awareness of the early onset of risk behaviors among urban adolescent girls is important for fostering positive parenting practices which, in turn, may help parents support their daughters’ healthier choices. PMID:18407045

  18. 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.

  19. 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.

  20. Unenhanced MDCT in Suspected Urolithiasis: Improved Stone Detection and Density Measurements Using Coronal Maximum-Intensity-Projection Images

    PubMed Central

    Corwin, Michael T.; Hsu, Margaret; McGahan, John P.; Wilson, Machelle; Lamba, Ramit

    2016-01-01

    OBJECTIVE The purpose of this study was to determine whether coronal maximum-intensity-projection (MIP) reformations improve urinary tract stone detection and density measurements compared with routine axial and coronal images. MATERIALS AND METHODS Forty-five consecutive patients who underwent MDCT for suspected urolithiasis were included. Two radiologists independently determined the number of stones on 5-, 3-, and 1.25-mm axial, 5- and 3-mm coronal, and 5-mm coronal MIP images. The reference standard was obtained by consensus review using all six datasets. Stone density was determined for all calculi 4 mm or larger on all datasets. RESULTS There were a total of 115 stones. Reader 1 identified 111 (96.5%), 112 (97.4%), 97 (84.3%), 102 (88.7%), 99 (86.1%), and 85 (73.9%) stones and reader 2 identified 105 (91.3%), 102 (88.7%), 85 (73.9%), 89 (77.4%), 89 (77.4%), and 76 (66.1%) stones on the MIP, 1.25-mm axial, 3-mm axial, 3-mm coronal, 5-mm coronal, and 5-mm axial images, respectively. Both readers identified more stones on the MIP images than on the 3- or 5-mm axial or coronal images (p < 0.0001). The mean difference in stone attenuation compared with the thin axial images was significantly less for the MIP images (44.6 HU) compared with 3-mm axial (235 HU), 3-mm coronal (309 HU), and 5-mm coronal (329.6 HU) or axial images (347.8 HU) (p < 0.0001). CONCLUSION Coronal MIP reformations allow more accurate identification and density measurements of urinary tract stones compared with routine axial and coronal reformations. PMID:24147474

  1. 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

  2. The feasibility of a scanner-independent technique to estimate organ dose from MDCT scans: Using CTDIvol to account for differences between scanners

    PubMed Central

    Turner, Adam C.; Zankl, Maria; DeMarco, John J.; Cagnon, Chris H.; Zhang, Di; Angel, Erin; Cody, Dianna D.; Stevens, Donna M.; McCollough, Cynthia H.; McNitt-Gray, Michael F.

    2010-01-01

    Purpose: Monte Carlo radiation transport techniques have made it possible to accurately estimate the radiation dose to radiosensitive organs in patient models from scans performed with modern multidetector row computed tomography (MDCT) scanners. However, there is considerable variation in organ doses across scanners, even when similar acquisition conditions are used. The purpose of this study was to investigate the feasibility of a technique to estimate organ doses that would be scanner independent. This was accomplished by assessing the ability of CTDIvol measurements to account for differences in MDCT scanners that lead to organ dose differences. Methods: Monte Carlo simulations of 64-slice MDCT scanners from each of the four major manufacturers were performed. An adult female patient model from the GSF family of voxelized phantoms was used in which all ICRP Publication 103 radiosensitive organs were identified. A 120 kVp, full-body helical scan with a pitch of 1 was simulated for each scanner using similar scan protocols across scanners. From each simulated scan, the radiation dose to each organ was obtained on a per mA s basis (mGy∕mA s). In addition, CTDIvol values were obtained from each scanner for the selected scan parameters. Then, to demonstrate the feasibility of generating organ dose estimates from scanner-independent coefficients, the simulated organ dose values resulting from each scanner were normalized by the CTDIvol value for those acquisition conditions. Results: CTDIvol values across scanners showed considerable variation as the coefficient of variation (CoV) across scanners was 34.1%. The simulated patient scans also demonstrated considerable differences in organ dose values, which varied by up to a factor of approximately 2 between some of the scanners. The CoV across scanners for the simulated organ doses ranged from 26.7% (for the adrenals) to 37.7% (for the thyroid), with a mean CoV of 31.5% across all organs. However, when organ

  3. Factors Associated with Underestimation of Weight Status among Caucasian, Latino, Filipino, and Korean Americans—DiLH Survey

    PubMed Central

    Choi, JiWon; Bender, Melinda S.; Arai, Shoshana; Fukuoka, Yoshimi

    2015-01-01

    Objective To describe weight misperception and to examine the influence of sociodemographic factors on underestimation of weight status in Caucasian, Latino, Filipino, and Korean Americans. Design Data from 886 non-pregnant adults who participated in a cross-sectional survey administered in English, Spanish, and Korean, were analyzed. The actual weight status derived from the participants’ body mass index (BMI) categories and their perceived weight status were compared. A multiple logistic regression model was used to explore if underestimation of weight status was associated with ethnicity, gender, and education level. Results Caucasians, Latinos, Filipinos, and Koreans represented 19.4%, 26.8%, 27.4%, and 26.4% of the total sample of 886. Overall, 2 in 3 participants correctly perceived their weight status, but 42% of Latinos underestimated their weight status and 22% of Koreans overestimated their weight status. Latino ethnicity, male, and low education (≤ high school) were related to greater underestimation of weight status (p < 0.05). In contrast, Korean ethnicity was related to less underestimation of weight status (p < 0.05). Conclusions Misperception of weight status should be counted in any efforts to develop a weight management intervention for Latino and Korean Americans. PMID:26118149

  4. Latent ability: grades and test scores systematically underestimate the intellectual ability of negatively stereotyped students.

    PubMed

    Walton, Gregory M; Spencer, Steven J

    2009-09-01

    Past research has assumed that group differences in academic performance entirely reflect genuine differences in ability. In contrast, extending research on stereotype threat, we suggest that standard measures of academic performance are biased against non-Asian ethnic minorities and against women in quantitative fields. This bias results not from the content of performance measures, but from the context in which they are assessed-from psychological threats in common academic environments, which depress the performances of people targeted by negative intellectual stereotypes. Like the time of a track star running into a stiff headwind, such performances underestimate the true ability of stereotyped students. Two meta-analyses, combining data from 18,976 students in five countries, tested this latent-ability hypothesis. Both meta-analyses found that, under conditions that reduce psychological threat, stereotyped students performed better than nonstereotyped students at the same level of past performance. We discuss implications for the interpretation of and remedies for achievement gaps. PMID:19656335

  5. Asymmetries of Poverty: Why Global Burden of Disease Valuations Underestimate the Burden of Neglected Tropical Diseases

    PubMed Central

    King, Charles H.; Bertino, Anne-Marie

    2008-01-01

    The disability-adjusted life year (DALY) initially appeared attractive as a health metric in the Global Burden of Disease (GBD) program, as it purports to be a comprehensive health assessment that encompassed premature mortality, morbidity, impairment, and disability. It was originally thought that the DALY would be useful in policy settings, reflecting normative valuations as a standardized unit of ill health. However, the design of the DALY and its use in policy estimates contain inherent flaws that result in systematic undervaluation of the importance of chronic diseases, such as many of the neglected tropical diseases (NTDs), in world health. The conceptual design of the DALY comes out of a perspective largely focused on the individual risk rather than the ecology of disease, thus failing to acknowledge the implications of context on the burden of disease for the poor. It is nonrepresentative of the impact of poverty on disability, which results in the significant underestimation of disability weights for chronic diseases such as the NTDs. Finally, the application of the DALY in policy estimates does not account for the nonlinear effects of poverty in the cost-utility analysis of disease control, effectively discounting the utility of comprehensively treating NTDs. The present DALY framework needs to be substantially revised if the GBD is to become a valid and useful system for determining health priorities. PMID:18365036

  6. Asbestos in Belgium: an underestimated health risk. The evolution of mesothelioma mortality rates (1969–2009)

    PubMed Central

    Van den Borre, Laura; Deboosere, Patrick

    2014-01-01

    Background: Although Belgium was once a major international manufacturer of asbestos products, asbestos-related diseases in the country have remained scarcely researched. Objectives: The aim of this study is to provide a descriptive analysis of Belgian mesothelioma mortality rates in order to improve the understanding of asbestos health hazards from an international perspective. Methods: Temporal and geographical analyses were performed on cause-specific mortality data (1969–2009) using quantitative demographic measures. Results were compared to recent findings on global mesothelioma deaths. Results: Belgium has one of the highest mesothelioma mortality rates in the world, following the UK, Australia, and Italy. With a progressive increase of male mesothelioma deaths in the mid-1980s, large differences in mortality rates between sexes are apparent. Mesothelioma deaths are primarily concentrated in geographic areas with proximity to former asbestos industries. Conclusions: Asbestos mortality in Belgium has been underestimated for decades. Our findings suggest that the location of asbestos industries is correlated with rates of mesothelioma, underlining the need to avert future asbestos exposure by thorough screening of potential contaminated sites and by pursuing a global ban on asbestos. PMID:24999848

  7. X-ray refinement significantly underestimates the level of microscopic heterogeneity in biomolecular crystals

    PubMed Central

    Kuzmanic, Antonija; Pannu, Navraj S.; Zagrovic, Bojan

    2014-01-01

    Biomolecular X-ray structures typically provide a static, time- and ensemble-averaged view of molecular ensembles in crystals. In the absence of rigid-body motions and lattice defects, B-factors are thought to accurately reflect the structural heterogeneity of such ensembles. In order to study the effects of averaging on B-factors, we employ molecular dynamics simulations to controllably manipulate microscopic heterogeneity of a crystal containing 216 copies of villin headpiece. Using average structure factors derived from simulation, we analyse how well this heterogeneity is captured by high-resolution molecular-replacement-based model refinement. We find that both isotropic and anisotropic refined B-factors often significantly deviate from their actual values known from simulation: even at high 1.0 Å resolution and Rfree of 5.9%, B-factors of some well-resolved atoms underestimate their actual values even sixfold. Our results suggest that conformational averaging and inadequate treatment of correlated motion considerably influence estimation of microscopic heterogeneity via B-factors, and invite caution in their interpretation. PMID:24504120

  8. Gender differences in the effects of parental underestimation of youths' secondary exposure to community violence.

    PubMed

    Zimmerman, Gregory M; Farrell, Amy S

    2013-10-01

    Secondary exposure to community violence is particularly detrimental for male youths, who disproportionately report witnessing community violence and suffering associated trauma-related symptoms. Yet, few studies have investigated whether parents perceive and report similar gender disparities among youths. In addition, few studies have examined the potentially negative effects of parent-child discord as to the youth's level of exposure to violence, or whether these effects vary across gender. Therefore, this study investigated whether differences between parents' and youths' reports of youths' exposure to violence, and the consequences of such reporting discord, varied across the gender of the youth informant. Participants were adolescents aged approximately 12 and 15 years at baseline (N = 1,517; 51 % female). Descriptive analyses indicated that male youths reported significantly higher levels of exposure to violence than female youths, but parents similarly under-reported their male and female children's experiences with violence. Hierarchical analyses indicated that parental underestimation of youths' exposure to violence had negative consequences. Moreover, significant interaction effects demonstrated that only females responded to reporting discord with internalizing problems. Conversely, both male and female youths responded to reporting discord with externalizing problems and offending. The results suggest that while parent-child discord is associated with negative outcomes for both male and female youths, discord may be disproportionately associated with negative outcomes among young females. The findings speak to the utility of examining the correlates and consequences of exposure to violence from a "gendered" perspective. PMID:23277295

  9. Short-term studies underestimate 30-generation changes in a butterfly metapopulation.

    PubMed Central

    Thomas, Chris D; Wilson, Robert J; Lewis, Owen T

    2002-01-01

    Most studies of rare and endangered species are based on work carried out within one generation, or over one to a few generations of the study organism. We report the results of a study that spans 30 generations (years) of the entire natural range of a butterfly race that is endemic to 35 km(2) of north Wales, UK. Short-term studies (surveys in single years and dynamics over 4 years) of this system led to the prediction that the regional distribution would be quite stable, and that colonization and extinction dynamics would be relatively unimportant. However, a longer-term study revealed unexpectedly high levels of population turnover (local extinction and colonization), affecting 18 out of the 20 patches that were occupied at any time during the period. Modelling the system (using the 'incidence function model' (IFM) for metapopulations) also showed higher levels of colonization and extinction with increasing duration of the study. The longer-term dynamics observed in this system can be compared, at a metapopulation level, with the increased levels of variation observed with increasing time that have been observed in single populations. Long-term changes may arise from local changes in the environment that make individual patches more or less suitable for the butterfly, or from unusual colonization or extinction events that take metapopulations into alternative states. One implication is that metapopulation and population viability analyses based on studies that cover only a few animal or plant generations may underestimate extinction threats. PMID:11916471

  10. Misdiagnosis of Sacral Stress Fracture: An Underestimated Cause of Low Back Pain in Pregnancy?

    PubMed Central

    Perdomo, Ambar Deschamps; Tomé-Bermejo, Félix; Piñera, Angel R.; Alvarez, Luis

    2015-01-01

    Patient: Female, 28 Final Diagnosis: Sacral stress fracture Symptoms: Lumbosacral pain during pregnancy Medication: — Clinical Procedure: Activity modification • conservative treatment Specialty: Orthopedics and Traumatology Objective: Challenging differential diagnosis Background: Sacral stress fracture during pregnancy is an uncommon condition with unclear pathophysiology, presenting with non-specific symptoms and clinical findings. To date, few cases have been published in the literature describing the occurrence of sacral stress fracture during pregnancy. Case Report: We report a 28-year-old primigravid patient who developed lumbosacral pain at the end of the second trimester. Symptoms were overlooked throughout pregnancy and the postpartum period, resulting in the development of secondary chronic gait and balance problems. Conclusions: Stress fracture of the sacrum should be included in the differential diagnosis of low back and sacral pain during pregnancy. Its prevalence is probably underestimated because of the lack of specificity of the symptoms. Plain radiographs are not appropriate due to radiation exclusion; magnetic resonance is the only method that can be applied safely. There is limited information on natural history but many patients are expected to have a benign course. However, misdiagnosis may lead to prolonged morbidity and the development of secondary gait abnormalities. Stress fracture of the sacrum should be included in the differential diagnosis of low back and sacral pain during pregnancy. A high index of suspicion is necessary to establish an early diagnosis and appropriate treatment. PMID:25656418

  11. National joint registry data underestimates the burden of prosthetic joint infection

    PubMed Central

    Young, Simon; Zhu, Mark; Ravi, Saiprasad; Luey, Chris

    2016-01-01

    Objective: Joint registries are powerful tools for tracking outcomes following joint arthroplasty. However recent literature has exposed deficiencies in data accuracy when reporting re-operations for prosthetic joint infections (PJI), particularly when no components are changed. The aim of this study was to compare accuracy of data from the New Zealand Joint Registry (NZJR) to a multi-centre audit of hospital records to establish the rate of capture for PJI reoperations. Methods: We followed 4009 patients undergoing total knee or hip arthroplasty performed at the three tertiary referral hospitals from January 2006 to December 2008 for two years. The reoperation rate for PJIs was extracted from the NZJR. In addition, an audit of hospital records for the same patients was carried out to identify reoperations for PJI. The audit data was then compared to the NZJR data. Results: The NZJR reported a reoperation rate of 0.67% for PJI within two years of the primary arthroplasty compared to 1.1% from the audit of hospital records, giving the NZJR a sensitivity of 63%. Only 36% of washout only procedures and 58% of modular exchange procedures were captured. Surgeons were more likely to report PJIs to NZJR if they performed the primary procedure. Conclusion: National joint registry data significantly underestimates the rate of reoperation for PJI. Strategies for improving data accuracy may include revising the registry forms to include reoperation without change of components and frequent validation of national data with other databases.

  12. New Zealand Joint Registry data underestimates the rate of prosthetic joint infection.

    PubMed

    Zhu, Mark; Ravi, Saiprasad; Frampton, Chris; Luey, Chris; Young, Simon

    2016-08-01

    Background and purpose - Recent studies have revealed deficiencies in the accuracy of data from joint registries when reoperations for prosthetic joint infections (PJIs) are reported, particularly when no components are changed. We compared the accuracy of data from the New Zealand Joint Registry (NZJR) to a multicenter audit of hospital records to establish the rate of capture for PJI reoperations. Methods - 4,009 cases undergoing total knee or hip arthroplasty performed at 3 tertiary referral hospitals over a 3-year period were audited using multiple hospital datasets and the NZJR. The number of reoperations for PJI that were performed within 2 years of the primary arthroplasty was obtained using both methods and the data were compared. Results - The NZJR reported a 2-year reoperation rate for PJI of 0.67%, as compared to 1.1% from the audit of hospital records, giving the NZJR a sensitivity of 63%. Only 4 of 11 debridement-in-situ-only procedures and 7 of 12 modular exchange procedures were captured in the NZJR. Interpretation - The national joint registry underestimated the rate of reoperation for PJI by one third. Strategies for improving the accuracy of data might include revising and clarifying the registry forms to include all reoperations for PJI and frequent validation of the registry data against other databases. PMID:27348450

  13. 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.

  14. Concomitant spuriously elevated white blood cell count, a previously underestimated phenomenon in EDTA-dependent pseudothrombocytopenia.

    PubMed

    Xiao, Yufei; Xu, Yang

    2015-01-01

    The proportion and potential risk of concomitant spuriously elevated white blood cell count (SEWC) are underestimated in ethylenediaminetetraacetic acid (EDTA)-dependent pseudothrombocytopenia (PTCP). The proportion, kinetics and prevention of SEWC remain poorly understood. A total of 25 patients with EDTA-dependent PTCP were enrolled in this study. With the hematology analyzer Coulter LH 750, we determined the time courses of WBC count, WBC differential and platelet count in EDTA- and sodium citrate-anticoagulated blood, respectively. Blood smears were prepared to inspect the presence of platelet clumps using light microscopy. The effect of automatic instrumental correction on the extent of SEWC was evaluated. The proportion of SEWC was 92% in EDTA-dependent PTCP and 73.9% of SEWCs were within the normal range. The development of SEWC was time-dependent, and neutrophils and lymphocytes were the main subpopulations involved in SEWC. A strong and significant correlation (r = 0.9937, p < 0.001) was found between the increased WBC count and the decreased platelet count. Both corrected and uncorrected WBC counts at 15 minutes or later after blood collection in EDTA were significantly higher than their basal counts, respectively, p < 0.05. Interestingly, in citrated blood, WBC counts after blood collection were not significantly different from its basal counts, p > 0.05. A high proportion of concomitant SEWCs, which are mainly within normal range, are present in patients with EDTA-dependent PTCP. Proper interpretation of SEWC is crucial to avoid clinic errors. SEWC develops in a time-dependent pattern, although the Coulter LH 750 only partly mitigates the extent of SEWC, sodium citrate is able to effectively prevent SEWC. PMID:25275874

  15. Underestimation of Species Richness in Neotropical Frogs Revealed by mtDNA Analyses

    PubMed Central

    Fouquet, Antoine; Gilles, André; Vences, Miguel; Marty, Christian; Blanc, Michel; Gemmell, Neil J.

    2007-01-01

    Background Amphibians are rapidly vanishing. At the same time, it is most likely that the number of amphibian species is highly underestimated. Recent DNA barcoding work has attempted to define a threshold between intra- and inter-specific genetic distances to help identify candidate species. In groups with high extinction rates and poorly known species boundaries, like amphibians, such tools may provide a way to rapidly evaluate species richness. Methodology Here we analyse published and new 16S rDNA sequences from 60 frog species of Amazonia-Guianas to obtain a minimum estimate of the number of undescribed species in this region. We combined isolation by distance, phylogenetic analyses, and comparison of molecular distances to evaluate threshold values for the identification of candidate species among these frogs. Principal Findings In most cases, geographically distant populations belong to genetically highly distinct lineages that could be considered as candidate new species. This was not universal among the taxa studied and thus widespread species of Neotropical frogs really do exist, contrary to previous assumptions. Moreover, the many instances of paraphyly and the wide overlap between distributions of inter- and intra-specific distances reinforce the hypothesis that many cryptic species remain to be described. In our data set, pairwise genetic distances below 0.02 are strongly correlated with geographical distances. This correlation remains statistically significant until genetic distance is 0.05, with no such relation thereafter. This suggests that for higher distances allopatric and sympatric cryptic species prevail. Based on our analyses, we propose a more inclusive pairwise genetic distance of 0.03 between taxa to target lineages that could correspond to candidate species. Conclusions Using this approach, we identify 129 candidate species, two-fold greater than the 60 species included in the current study. This leads to estimates of around 170 to 460

  16. Closed system respirometry may underestimate tissue gas exchange and bias the respiratory exchange ratio (RER).

    PubMed

    Malte, Christian Lind; Nørgaard, Simon; Wang, Tobias

    2016-02-01

    Closed respirometry is a commonly used method to measure gas exchange in animals due to its apparent simplicity. Typically, the rates of O2 uptake and CO2 excretion (VO2 and VCO2, respectively) are assumed to be in steady state, such that the measured rates of gas exchange equal those at tissue level. In other words, the respiratory gas exchange ratio (RER) is assumed to equal the respiratory quotient (RQ). However, because the gas concentrations change progressively during closure, the animal inspires air with a progressively increasing CO2 concentration and decreasing O2 concentration. These changes will eventually affect gas exchange causing the O2 and CO2 stores within the animal to change. Because of the higher solubility/capacitance of CO2 in the tissues of the body, VCO2 will be more affected than VO2, and we hypothesize therefore that RER will become progressively underestimated as closure time is prolonged. This hypothesis was addressed by a combination of experimental studies involving closed respirometry on ball pythons (Python regius) as well as mathematical models of gas exchange. We show that increased closed duration of the respirometer reduces RER by up to 13%, and these findings may explain previous reports of RER values being below 0.7. Our model reveals that the maximally possible reduction in RER is determined by the storage capacity of the body for CO2 (product of size and specific capacitance) relative to the respirometer storage capacity. Furthermore, modeling also shows that pronounced ventilatory and circulatory response to hypercapnia can alleviate the reduction in RER. PMID:26523499

  17. Underestimation of boreal soil carbon stocks by mathematical soil carbon models linked to soil nutrient status

    NASA Astrophysics Data System (ADS)

    Ťupek, Boris; Ortiz, Carina A.; Hashimoto, Shoji; Stendahl, Johan; Dahlgren, Jonas; Karltun, Erik; Lehtonen, Aleksi

    2016-08-01

    Inaccurate estimate of the largest terrestrial carbon pool, soil organic carbon (SOC) stock, is the major source of uncertainty in simulating feedback of climate warming on ecosystem-atmosphere carbon dioxide exchange by process-based ecosystem and soil carbon models. Although the models need to simplify complex environmental processes of soil carbon sequestration, in a large mosaic of environments a missing key driver could lead to a modeling bias in predictions of SOC stock change.We aimed to evaluate SOC stock estimates of process-based models (Yasso07, Q, and CENTURY soil sub-model v4) against a massive Swedish forest soil inventory data set (3230 samples) organized by a recursive partitioning method into distinct soil groups with underlying SOC stock development linked to physicochemical conditions.For two-thirds of measurements all models predicted accurate SOC stock levels regardless of the detail of input data, e.g., whether they ignored or included soil properties. However, in fertile sites with high N deposition, high cation exchange capacity, or moderately increased soil water content, Yasso07 and Q models underestimated SOC stocks. In comparison to Yasso07 and Q, accounting for the site-specific soil characteristics (e. g. clay content and topsoil mineral N) by CENTURY improved SOC stock estimates for sites with high clay content, but not for sites with high N deposition.Our analysis suggested that the soils with poorly predicted SOC stocks, as characterized by the high nutrient status and well-sorted parent material, indeed have had other predominant drivers of SOC stabilization lacking in the models, presumably the mycorrhizal organic uptake and organo-mineral stabilization processes. Our results imply that the role of soil nutrient status as regulator of organic matter mineralization has to be re-evaluated, since correct SOC stocks are decisive for predicting future SOC change and soil CO2 efflux.

  18. Neglecting rice milling yield and quality underestimates economic losses from high-temperature stress.

    PubMed

    Lyman, Nathaniel B; Jagadish, Krishna S V; Nalley, L Lanier; Dixon, Bruce L; Siebenmorgen, Terry

    2013-01-01

    Future increases in global surface temperature threaten those worldwide who depend on rice production for their livelihoods and food security. Past analyses of high-temperature stress on rice production have focused on paddy yield and have failed to account for the detrimental impact of high temperatures on milling quality outcomes, which ultimately determine edible (marketable) rice yield and market value. Using genotype specific rice yield and milling quality data on six common rice varieties from Arkansas, USA, combined with on-site, half-hourly and daily temperature observations, we show a nonlinear effect of high-temperature stress exposure on yield and milling quality. A 1 °C increase in average growing season temperature reduces paddy yield by 6.2%, total milled rice yield by 7.1% to 8.0%, head rice yield by 9.0% to 13.8%, and total milling revenue by 8.1% to 11.0%, across genotypes. Our results indicate that failure to account for changes in milling quality leads to understatement of the impacts of high temperatures on rice production outcomes. These dramatic losses result from reduced paddy yield and increased percentages of chalky and broken kernels, which together decrease the quantity and market value of milled rice. Recently published estimates show paddy yield reductions of up to 10% across the major rice-producing regions of South and Southeast Asia due to rising temperatures. The results of our study suggest that the often-cited 10% figure underestimates the economic implications of climate change for rice producers, thus potentially threatening future food security for global rice producers and consumers. PMID:23991056

  19. 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

  20. Disguised Distress in Children and Adolescents "Flying under the Radar": Why Psychological Problems Are Underestimated and How Schools Must Respond

    ERIC Educational Resources Information Center

    Flett, Gordon L.; Hewitt, Paul L.

    2013-01-01

    It is now recognized that there is a very high prevalence of psychological disorders among children and adolescents and relatively few receive psychological treatment. In the current article, we present the argument that levels of distress and dysfunction among young people are substantially underestimated and the prevalence of psychological…

  1. Underestimated public health risks caused by overestimated VOC removal in wastewater treatment processes.

    PubMed

    Yang, Junchen; Wang, Kun; Zhao, Qingliang; Huang, Likun; Yuan, Chung-Shin; Chen, Wei-Hsiang; Yang, Wen-Bin

    2014-02-01

    The uncontrolled release of volatile organic compounds (VOCs) from wastewater treatment plants (WWTPs) and the adverse health effects on the public have been of increasing concern. In this study, a lab-scale bioreactor was prepared to analyze the mass distribution of three aromatic (benzene, toluene, and xylenes) and four chlorinated VOCs (chloroform, carbon tetrachloride, trichloroethylene, and tetrachloroethylene) among the air, water and sludge phases in wastewater treatment processes. The VOC distribution through a full-scale WWTP in northern China was further investigated with respect to the effects of seasonal temperature variations and treatment technologies, followed by the cancer risk assessment using a steady-state Gaussian plume model (Industrial Source Complex) to simulate the atmospheric behaviors of the VOCs emitted from the WWTP. It was found that three aromatic hydrocarbons, notably benzene, were more readily released from the wastewater into the atmosphere, whereas the chlorinated compounds except chloroform were mainly present in the water phase through the treatment processes. The primary clarifier was the technology releasing high levels of VOCs into the atmosphere from the wastewater. The extents of volatilization or biodegradation, two important mechanisms to remove VOCs from wastewater, appeared to be determined by the physicochemical characteristics of the compounds, as the influence of treatment technologies (e.g., aeration) and seasonal temperature variations was rather limited. More importantly, the people living in the areas even more than 4 km away from the WWTP were still potentially exposed to cancer risks exceeding the regulatory threshold limit. The findings described the complex nature of VOC emissions from WWTPs and quantitatively indicated that the associated health impacts on the public near the WWTPs could be severely underestimated, whereas their treatment efficiencies by wastewater treatment technologies were overestimated

  2. The underestimated challenges of burst-mode WDM transmission in TWDM-PON

    NASA Astrophysics Data System (ADS)

    Bonk, R.; Poehlmann, W.; van Veen, D.; Galaro, J.; Farah, R.; Schmuck, H.; Pfeiffer, Th.

    2015-12-01

    In this paper, the underestimated challenges of the burst-mode operation in the upstream path of time-and-wavelength-division-multiplexed passive optical networks are analyzed. Various challenges are disclosed, the influence of the associated physical effects on the signal quality is discussed and mitigation proposals are described: Intra-channel cross-talk can arise from optical network units induced background amplified-spontaneous emission noise and inter-channel cross-talk can be caused by non-ideal filter suppression between wavelength channels at the optical line termination receivers. Such cross-talk effects can be counteracted by reducing the laser burst-signal output power as well as its rival noise power simultaneously, i.e. by applying power leveling. A fast frequency drift in burst-mode operation is inherent to directly modulated lasers, but depends on the specific laser design, the laser output power and the burst length. Mitigation mechanisms are an optimized non-standard laser design or a specific mode of operation, e.g. an increase of the frequency drift during the preamble of the burst. The power dynamic range an optical pre-amplifier as part of the upstream signal receivers needs to handle can be in range of up to 40 dB, because of the multi-wavelength channel operation and of the optical distribution network differential path loss. This power dynamic faced at the receiver can not only cause challenges for the optical amplifier, but also for the burst-mode receivers. Additionally, the physical layer operation and maintenance of the upstream path is challenging too. Each optical network unit laser needs to be either wavelength pre-calibrated, which adds undesired costs or cross-channel synchronization of ranging windows has to be ensured. Otherwise rogue optical network unit behavior in wavelength and time domain will deteriorate system performance with every new optical network unit entering the network. Further, the operation of the optical

  3. Pesticide Mixtures, Endocrine Disruption, and Amphibian Declines: Are We Underestimating the Impact?

    PubMed Central

    Hayes, Tyrone B.; Case, Paola; Chui, Sarah; Chung, Duc; Haeffele, Cathryn; Haston, Kelly; Lee, Melissa; Mai, Vien Phoung; Marjuoa, Youssra; Parker, John; Tsui, Mable

    2006-01-01

    increase in plasma levels of the stress hormone corticosterone. Although it cannot be determined whether all the pesticides in the mixture contribute to these adverse effects or whether some pesticides are effectors, some are enhancers, and some are neutral, the present study revealed that estimating ecological risk and the impact of pesticides on amphibians using studies that examine only single pesticides at high concentrations may lead to gross underestimations of the role of pesticides in amphibian declines. PMID:16818245

  4. Underestimation of soil carbon stocks by Yasso07, Q, and CENTURY models in boreal forest linked to overlooking site fertility

    NASA Astrophysics Data System (ADS)

    Ťupek, Boris; Ortiz, Carina; Hashimoto, Shoji; Stendahl, Johan; Dahlgren, Jonas; Karltun, Erik; Lehtonen, Aleksi

    2016-04-01

    The soil organic carbon stock (SOC) changes estimated by the most process based soil carbon models (e.g. Yasso07, Q and CENTURY), needed for reporting of changes in soil carbon amounts for the United Nations Framework Convention on Climate Change (UNFCCC) and for mitigation of anthropogenic CO2 emissions by soil carbon management, can be biased if in a large mosaic of environments the models are missing a key factor driving SOC sequestration. To our knowledge soil nutrient status as a missing driver of these models was not tested in previous studies. Although, it's known that models fail to reconstruct the spatial variation and that soil nutrient status drives the ecosystem carbon use efficiency and soil carbon sequestration. We evaluated SOC stock estimates of Yasso07, Q and CENTURY process based models against the field data from Swedish Forest Soil National Inventories (3230 samples) organized by recursive partitioning method (RPART) into distinct soil groups with underlying SOC stock development linked to physicochemical conditions. These models worked for most soils with approximately average SOC stocks, but could not reproduce higher measured SOC stocks in our application. The Yasso07 and Q models that used only climate and litterfall input data and ignored soil properties generally agreed with two third of measurements. However, in comparison with measurements grouped according to the gradient of soil nutrient status we found that the models underestimated for the Swedish boreal forest soils with higher site fertility. Accounting for soil texture (clay, silt, and sand content) and structure (bulk density) in CENTURY model showed no improvement on carbon stock estimates, as CENTURY deviated in similar manner. We highlighted the mechanisms why models deviate from the measurements and the ways of considering soil nutrient status in further model development. Our analysis suggested that the models indeed lack other predominat drivers of SOC stabilization

  5. Detection of small (≤ 2 cm) pancreatic adenocarcinoma and surrounding parenchyma: correlations between enhancement patterns at triphasic MDCT and histologic features

    PubMed Central

    2014-01-01

    Background The aim is to assess the time-density curves (TDCs) and correlate the histologic results for small (≤ 2 cm) PDA and surrounding parenchyma at triphasic Multidetector-row CT (MDCT). Methods Triphasic MDCT scans of 38 consecutive patients who underwent surgery for a small PDA were retrospectively reviewed. The TDCs were analyzed and compared with histologic examination of the PDA and pancreas upstream/downstream in all cases. Three enhancement patterns were identified: 1) enhancement peak during pancreatic parenchymal phase (PPP) followed by a rapid decline on portal venous phase (PVP) and delayed phase (DP) at 5 minutes (type 1 pattern: normal pancreas); 2) maximum enhancement in PVP that gradually decreases in DP (type 2 pattern: mild chronic pancreatitis or PDA with mild fibrous stroma); 3) progressive enhancement with maximum peak in DP (type 3 pattern: severe chronic pancreatitis or PDA with severe fibrous stroma). A p value less than 0.05 was considered statistically significant. Sensitivity was calculated for PDA detection and an attenuation difference with the surrounding tissue of at least 10 HU was considered. Results PDA showed type 2 pattern in 5/38 cases (13.2%) and type 3 pattern in 33/38 cases (86,8%). Pancreas upstream to the tumor had type 2 pattern in 20/38 cases (52,6%) and type 3 pattern in 18/38 cases (47,4%). Pancreas downstream to the tumor had type 1 pattern in 19/25 cases (76%) and type 2 pattern in 6/25 cases (24%). Attenuation difference between tumor and parenchyma upstream was higher of 10 UH on PPP in 31/38 patients (sensitivity = 81.6%), on PVP in 29/38 (sensitivity = 76.3%) and on DP in 17/38 (sensitivity = 44.7%). Attenuation difference between tumor and parenchyma downstream was higher of 10 UH on PPP in 25/25 patients (sensitivity = 100%), on PVP in 22/25 (sensitivity = 88%) and on DP in 20/25 (sensitivity = 80%). Small PDAs were isodense to the pancreas upstream to the tumor, and therefore

  6. Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions

    NASA Astrophysics Data System (ADS)

    Stohl, A.; Klimont, Z.; Eckhardt, S.; Kupiainen, K.; Shevchenko, V. P.; Kopeikin, V. M.; Novigatsky, A. N.

    2013-09-01

    BC surface concentrations due to residential combustion by 68% when using daily emissions. A large part (93%) of this systematic increase can be captured also when using monthly emissions; the increase is compensated by a decreased BC burden at lower latitudes. In a comparison with BC measurements at six Arctic stations, we find that using daily-varying residential combustion emissions and introducing gas flaring emissions leads to large improvements of the simulated Arctic BC, both in terms of mean concentration levels and simulated seasonality. Case studies based on BC and carbon monoxide (CO) measurements from the Zeppelin observatory appear to confirm flaring as an important BC source that can produce pollution plumes in the Arctic with a high BC / CO enhancement ratio, as expected for this source type. BC measurements taken during a research ship cruise in the White, Barents and Kara seas north of the region with strong flaring emissions reveal very high concentrations of the order of 200-400 ng m-3. The model underestimates these concentrations substantially, which indicates that the flaring emissions (and probably also other emissions in northern Siberia) are rather under- than overestimated in our emission data set. Our results suggest that it may not be "vertical transport that is too strong or scavenging rates that are too low" and "opposite biases in these processes" in the Arctic and elsewhere in current aerosol models, as suggested in a recent review article (Bond et al., Bounding the role of black carbon in the climate system: a scientific assessment, J. Geophys. Res., 2013), but missing emission sources and lacking time resolution of the emission data that are causing opposite model biases in simulated BC concentrations in the Arctic and in the mid-latitudes.

  7. 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.

  8. MDCT findings of renal cell carcinoma associated with Xp11.2 translocation and TFE3 gene fusion and papillary renal cell carcinoma.

    PubMed

    Woo, Sungmin; Kim, Sang Youn; Lee, Myoung Seok; Moon, Kyung Chul; Kim, See Hyung; Cho, Jeong Yeon; Kim, Seung Hyup

    2015-03-01

    OBJECTIVE. The purpose of this study was to compare the MDCT features of renal cell carcinoma (RCC) associated with Xp11.2 translocation and TFE3 gene fusion (Xp11 RCC) and papillary RCC. MATERIALS AND METHODS. The study included 19 and 39 patients with histologically proven Xp11 RCC and papillary RCC, respectively, who underwent multiphase renal MDCT before nephrectomy. CT findings were compared between Xp11 RCC and papillary RCC using the Student t test and chi-square test. Subgroup analyses of small (< 4 cm) renal masses for these features were performed. RESULTS. Patients with Xp11 RCC were younger (p < 0.001), and it was more prevalent in women (p = 0.007). Tumor size was greater in Xp11 RCC (p = 0.004) and more common in cystic change (p < 0.001). Calcification and unenhanced high-attenuating areas were more frequent in Xp11 RCC (p = 0.001 and 0.026, respectively). Xp11 RCCs were more prevalent in lymph node and distant metastasis (p < 0.001 and p = 0.031, respectively). Xp11 RCC and papillary RCC showed no significant difference in epicenter, margin, and venous and collecting duct invasion (p = 0.403-1.000). Although Xp11 RCC and papillary RCC had lower attenuation than the renal cortex on corticomedullary and early excretory phases (p < 0.001), only Xp11 RCCs were hyperattenuating to the cortex on the unenhanced phase (p < 0.001). Xp11 RCCs had significantly higher attenuation compared with papillary RCCs on all phases (p ≤ 0.02). Regarding small masses, cystic change, calcification, and lymph node metastasis were still more frequent in Xp11 RCCs (p ≤ 0.016). CONCLUSION. Greater size, more cystic change, calcification, high-attenuating areas on unenhanced imaging, and lymph node and distant metastasis were helpful for differentiating Xp11 RCC from papillary RCC. PMID:25714283

  9. Two-way hydro-mechanical coupling is required not to underestimate fault fluid flow in numerical simulations

    NASA Astrophysics Data System (ADS)

    Tillner, Elena; Nakaten, Benjamin; Kempka, Thomas

    2015-04-01

    Pressure elevation in saturated porous media induced by any kind of fluid injection into a reservoir generally triggers pore volume changes in the host rocks and/or adjacent fault zones due to volumetric strain increments. Consequently, the hydraulic conductivity of faults can increase by several orders of magnitude, and thus allows for unwanted upward migration of fluids accompanied by environmental impacts in shallower aquifers. Interaction between hydraulic and mechanical processes is significant in this context. Hence, coupled hydro-mechanical simulations were applied in the present study to assess the impact of saline aquifer utilization on the recent stress state and fluid flow at a prospective German onshore carbon dioxide storage site, in particular with regard to present fault zones. The location of interest is a Mesozoic anticline structure, approximately 80 km southeast of the German capital Berlin [1, 2]. A Lower Triassic saline sandstone aquifer, the Detfurth Formation located at a depth of about 1,080 m, was chosen as storage horizon for 34 Mt CO2, injected within 20 years. Four major regional fault zones consisting of individual faults with different dip angles and directions are located at a distance of minimum 5 km and maximum 45 km from the injection location at the anticline top. The storage formation is overlain by several cap rocks from the Triassic to Tertiary with thicknesses varying between 50 m and 520 m. The Upper Tertiary Rupelian clay forms the main regional barrier separating salt water bearing aquifers from Tertiary and Quaternary freshwater reservoirs. However, glacial erosion resulted in thinning or a complete absence of the Rupelian clay in some areas that meet parts of the fault zones. The structural geological model applied for coupled hydro-mechanical simulations has an extent of 70 km x 100 km and extends from 5,000 m depth up to the ground surface. Multi-phase flow simulations were carried out using the scientific code TOUGH2

  10. Don’t underestimate fournier’s gangrene: report of 8 cases in 10 month survey

    PubMed Central

    Danesh, Hosein Ali; Saboury, Mahdy; Sabzi, Ameneh; Saboury, Moosa; Jafary, Maryamsadat; Saboury, Shahriar

    2015-01-01

    Background: Fourniers gangrene caused by synergic aerobic and anaerobic organism is a life threatening disorder. Methods: The medical records of 8 among 839 patients admitted to imam ali general hospital Zahedan university of Medical Sciences with fourniers gangrene during the 10 months period between 2012 and 2013 were reviewed. Results: The most common etiology and presentation were abscess and perianal pain respectively. Mixed bacterial flora was common finding in patient. Single debridement was carried out in 2 patients and repeated procedure was needed in 6. Conclusion: This disease is characterized with high mortality of up to 75% but in our study the rate was 37.5%. In other studies diabetes mellitus was found to be the common condition related to fourniers gangrene but in our study the common etiology was perianal abscess. Fourniers gangrene should be rule out in any patient with perianal pain and flulike, swelling skin. PMID:26034725

  11. Diagnosis of Columnar Cell Lesions and Atypical Ductal Hyperplasia by Ultrasound-Guided Core Biopsy: Findings Associated with Underestimation of Breast Carcinoma.

    PubMed

    Ahn, Hye Shin; Jang, Mijung; Kim, Sun Mi; Yun, Bo La; Kim, Sung-Won; Kang, Eun Young; Park, So Yeon

    2016-07-01

    The aim of the study described here was to determine underestimation rates and identify radiologic predictors of underestimation for columnar cell lesions (CCLs) and atypical ductal hyperplasia (ADH) detected by ultrasound-guided core needle biopsy. A total of 103 CCLs and ADH lesions in 100 patients diagnosed by ultrasound-guided core needle biopsy were evaluated. Breast sonographic and mammographic findings were reviewed, and underestimation rates were determined by surgical excision, percutaneous vacuum-assisted excision or 2-y imaging follow-up. All underestimated lesions were ductal carcinoma in situ, and the underestimation rates of flat epithelial atypia (FEA), FEA + ADH and ADH were 5.9% (1/17), 44.4% (4/9) and 27.3% (12/44), respectively. There was no underestimation of CCLs without atypia. The presence of calcifications on ultrasound was significantly associated with underestimation (p = 0.010). Therefore, except for CCLs without atypia, all other lesions may require excision, especially when calcification is present on ultrasound or when FEA + ADH is found. PMID:27067419

  12. Loiasis--a neglected and under-estimated affliction: endemicity, morbidity and perceptions in eastern Cameroon.

    PubMed

    Takougang, I; Meli, J; Lamlenn, S; Tatah, P N; Ntep, M

    2007-03-01

    Loiasis is a neglected disease that may have great social and economic impact in some endemic areas. This study was designed to update the geographical distribution of loiasis and assess the frequency and perceptions of the clinical signs of the disease in the Eastern province of Cameroon. The investigation covered 32 villages and involved 4146 respondents. Human infection with Loa loa was endemic in all the study villages but the prevalence of microfilaraemia generally decreased from south to north. All of the study villages had local names for eye worm and Calabar swellings that varied in meaning and among the various ethnic groups. The most common traditional treatment for eye worm was garlic or onion juice, which is dripped into the affected eye. The body sites that were most affected by Calabar swellings were the upper (30%) or lower (32%) limbs. The swellings were very painful (46%), mildly painful (28%) or painless (26%). Most respondents (94%) reported that the swellings itched. The prevalence of L. loa microfilaraemia in most of the study villages was >20%. These villages are clearly at risk of severe adverse events, with encephalopathy, following mass distribution of ivermectin. The prevalence of the main clinical manifestations of loiasis (i.e. eye worm and/or Calabar swellings) was twice that of detectable microfilaraemia. PMID:17316501

  13. Absorbed Radiation Dose in Radiosensitive Organs During Coronary CT Angiography Using 320-MDCT: Effect of Maximum Tube Voltage and Heart Rate Variations

    PubMed Central

    Nikolic, Boris; Khosa, Faisal; Lin, Pei-Jan Paul; Khan, Atif N.; Sarwar, Sheryar; Yam, Chun-Shan; Court, Laurence E.; Raptopoulos, Vassilios; Clouse, Melvin E.

    2012-01-01

    OBJECTIVE The purpose of this article is to estimate the absorbed radiation dose in radiosensitive organs during coronary MDCT angiography using 320-MDCT and to determine the effects of tube voltage variation and heart rate (HR) control on absorbed radiation dose. MATERIALS AND METHODS Semiconductor field effect transistor detectors were used to measure absorbed radiation doses for the thyroid, midbreast, breast, and midlung in an anthropomorphic phantom at 100, 120, and 135 kVp at two different HRs of 60 and 75 beats per minute (bpm) with a scan field of view of 320 mm, 400 mA, 320 × 0.5 mm detectors, and 160 mm collimator width (160 mm range). The paired Student’s t test was used for data evaluation. RESULTS At 60 bpm, absorbed radiation doses for 100, 120, and 135 kVp were 13.41 ± 3.59, 21.7 ± 4.12, and 29.28 ± 5.17 mGy, respectively, for midbreast; 11.76 ± 0.58, 18.86 ± 1.06, and 24.82 ± 1.45 mGy, respectively, for breast; 12.19 ± 2.59, 19.09 ± 3.12, and 26.48 ± 5.0 mGy, respectively, for lung; and 0.37 ± 0.14, 0.69 ± 0.14, and 0.92 ± 0.2 mGy, respectively, for thyroid. Corresponding absorbed radiation doses for 75 bpm were 38.34 ± 2.02, 59.72 ± 3.13, and 77.8 ± 3.67 mGy for midbreast; 26.2 ± 1.74, 44 ± 1.11, and 52.84 ± 4.07 mGy for breast; 38.02 ± 1.58, 58.89 ± 1.68, and 78 ± 2.93 mGy for lung; and 0.79 ± 0.233, 1.04 ± 0.18, and 2.24 ± 0.52 mGy for thyroid. Absorbed radiation dose changes were significant for all organs for both tube voltage reductions as well as for HR control from 75 to 60 bpm at all tube voltage settings (p < 0.05). The absorbed radiation doses for the calcium score protocol were 11.2 ± 1.4 mGy for midbreast, 9.12 ± 0.48 mGy for breast, 10.36 ± 1.3 mGy for lung, and 0.4 ± 0.05 mGy for thyroid. CONCLUSION CT angiography with 320-MDCT scanners results in absorbed radiation doses in radiosensitive organs that compare favorably to those previously reported. Significant dose reductions can be achieved by tube

  14. Underestimating the effects of spatial heterogeneity due to individual movement and spatial scale: infectious disease as an example

    USGS Publications Warehouse

    Cross, Paul C.; Caillaud, Damien; Heisey, Dennis M.

    2013-01-01

    Many ecological and epidemiological studies occur in systems with mobile individuals and heterogeneous landscapes. Using a simulation model, we show that the accuracy of inferring an underlying biological process from observational data depends on movement and spatial scale of the analysis. As an example, we focused on estimating the relationship between host density and pathogen transmission. Observational data can result in highly biased inference about the underlying process when individuals move among sampling areas. Even without sampling error, the effect of host density on disease transmission is underestimated by approximately 50 % when one in ten hosts move among sampling areas per lifetime. Aggregating data across larger regions causes minimal bias when host movement is low, and results in less biased inference when movement rates are high. However, increasing data aggregation reduces the observed spatial variation, which would lead to the misperception that a spatially targeted control effort may not be very effective. In addition, averaging over the local heterogeneity will result in underestimating the importance of spatial covariates. Minimizing the bias due to movement is not just about choosing the best spatial scale for analysis, but also about reducing the error associated with using the sampling location as a proxy for an individual’s spatial history. This error associated with the exposure covariate can be reduced by choosing sampling regions with less movement, including longitudinal information of individuals’ movements, or reducing the window of exposure by using repeated sampling or younger individuals.

  15. Subalpine Species Response to Past Climate Change and Fire Activity: Are We Underestimating the Biotic Resilience?

    NASA Astrophysics Data System (ADS)

    Whitlock, C. L.; Iglesias, V.; Krause, T.

    2014-12-01

    Climate-change impacts on species distributions will be especially complex in mountain systems with steep environmental gradients and heterogeneous landscapes. In the western US, projected climate conditions include rising temperatures, decreased snowpack, and increased moisture deficits, all of which will impact species distributions at high elevations. Whitebark pine (Pinus albicaulis; WBP) is a keystone species in subalpine environments and one that is highly vulnerable to projected climate trends. In the past two decades, WBP populations dramatically declined as a result of bark beetle infestation, blister rust, high-severity fires, and drought. Species-niche modeling used to map future WPB distributions is based on the relation between present-day occurrence and bioclimatic parameters. While these models capture the realized niche, the full niche space inferred from paleo-observations appears to be much larger. To assess a broad range of bioclimatic conditions for WPB, we examined its response to past changes in climate, fire activity, and species competition. General additive modeling of pollen/charcoal data from the Greater Yellowstone area indicate that WBP reached maximum population size and distribution ~12,000 -7500 years ago and declined thereafter. Population dynamics tracked variations in summer insolation, such that WBP was most abundant when summer temperatures and fire frequency were higher than at present. Competition from lodgepole pine after ~10,000 years ago limited WBP at middle elevations. Paleoecological data indicate that the fundamental WBP niche is considerably larger than assumed, and simulations that project the demise of WBP in the next 50 years are probably too dramatic given WPB's ability to thrive under warm conditions and high fire activity in the past. Management strategies that reduce biotic competition and nonnative pathogens should help increase the future resilience of WBP and other subalpine species.

  16. Tidal marsh accretion processes in the San Francisco Bay-Delta - are our models underestimating the historic and future importance of plant-mediated organic accretion?

    NASA Astrophysics Data System (ADS)

    Windham-Myers, L.; Drexler, J. Z.; Byrd, K. B.; Schile, L. M.

    2012-12-01

    Peat-accreting coastal wetlands have the potential to keep elevational pace with sea-level rise, thus providing both adaptation and mitigation for expected rises in atmospheric concentrations of greenhouse gases (GHGs). Due to oxidation and sedimentation processes, marsh elevations are generally constrained by sea level rise (1-2 mm yr-1). However, the relative importance of mineral vs. organic accretion remain poorly understood. At least four lines of evidence from the brackish-fresh region of California's SFBay-Delta suggest that potential rates of organic accretion may be underestimated in calibration datasets of the last century. First, tidal marsh elevations have been maintained with changing rates of SLR over the past 6700 years even during periods of low sediment availability. Second, the presence of fibric remnants in historic peat cores suggests that millennial preservation of autochtonous material may be greater in the absence of mineral inputs. Third, an experimental restoration of emergent marsh on subsided peat soil has generated new "proto-peat" at average rates of 4 cm y-1, nearly 40-times mean sea level rise, storing an average of 1 kg C m-2 yr-1 since 1997. Fourth, annual measurements of root production of the dominant fresh-brackish marsh species tule (Schoenoplectus acutus) show high productivity and minimal sensitivity to variable tidal range elevations and fresh-brackish salinities. Separating the relative importance of belowground productivity from decomposition in driving rates of organic accretion may be possible by assessment of fibric remnants, as an index of organic "preservation". Using three distinct peat cores from a larger study with calibrated dating and geochemistry data, fibric remnants (particles >2mm) were assessed at 10 cm intervals and compared with physical and associated geochemical down-core variability (n=230 segments). The presence of fibric remnants was reduced in the presence of sediment, as indicated by mineral content

  17. 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

  18. Underestimation of the pentose–phosphate pathway in intact primary neurons as revealed by metabolic flux analysis

    PubMed Central

    Rodriguez-Rodriguez, Patricia; Fernandez, Emilio; Bolaños, Juan P

    2013-01-01

    The rates of glucose oxidized at glycolysis and pentose–phosphate pathway (PPP) in neurons are controversial. Using [3-3H]-, [1-14C]-, and [6-14C]glucose to estimate fluxes through these pathways in resting, intact rat cortical primary neurons, we found that the rate of glucose oxidized through PPP was, apparently, ∼14% of total glucose metabolized. However, inhibition of PPP rate-limiting step, glucose-6-phosphate (G6P) dehydrogenase, increased approximately twofold the glycolytic rate; and, knockdown of phosphoglucose isomerase increased ∼1.8-fold the PPP rate. Thus, in neurons, a considerable fraction of fructose-6-phosphate returning from the PPP contributes to the G6P pool that re-enters PPP, largely underestimating its flux. PMID:24064491

  19. Diagnostic underestimation of atypical ductal hyperplasia and ductal carcinoma in situ at percutaneous core needle and vacuum-assisted biopsies of the breast in a Brazilian reference institution*

    PubMed Central

    Badan, Gustavo Machado; Roveda Júnior, Decio; Piato, Sebastião; Fleury, Eduardo de Faria Castro; Campos, Mário Sérgio Dantas; Pecci, Carlos Alberto Ferreira; Ferreira, Felipe Augusto Trocoli; D'Ávila, Camila

    2016-01-01

    Objective To determine the rates of diagnostic underestimation at stereotactic percutaneous core needle biopsies (CNB) and vacuum-assisted biopsies (VABB) of nonpalpable breast lesions, with histopathological results of atypical ductal hyperplasia (ADH) or ductal carcinoma in situ (DCIS) subsequently submitted to surgical excision. As a secondary objective, the frequency of ADH and DCIS was determined for the cases submitted to biopsy. Materials and Methods Retrospective review of 40 cases with diagnosis of ADH or DCIS on the basis of biopsies performed between February 2011 and July 2013, subsequently submitted to surgery, whose histopathological reports were available in the internal information system. Biopsy results were compared with those observed at surgery and the underestimation rate was calculated by means of specific mathematical equations. Results The underestimation rate at CNB was 50% for ADH and 28.57% for DCIS, and at VABB it was 25% for ADH and 14.28% for DCIS. ADH represented 10.25% of all cases undergoing biopsy, whereas DCIS accounted for 23.91%. Conclusion The diagnostic underestimation rate at CNB is two times the rate at VABB. Certainty that the target has been achieved is not the sole determining factor for a reliable diagnosis. Removal of more than 50% of the target lesion should further reduce the risk of underestimation. PMID:26929454

  20. A method to compensate for the underestimation of collagen with polarized picrosirius red imaging in human artery atherosclerotic plaques

    NASA Astrophysics Data System (ADS)

    Greiner, C. A.; Grainger, S. J.; Su, J. L.; Madden, S. P.; Muller, J. E.

    2016-04-01

    Although picrosirius red (PSR) is known to be in quantifying collagen under polarized light (PL), commonly used linearly PL can result in an underestimation of collagen, as some of the fibers may appear dark if aligned with the transmission axis of the polarizers. To address this, a sample may be imaged with circularly polarized light at the expense of higher background intensity. However, the quality and alignment of the microscope illumination optics, polarizers and waveplates can still produce imaging variability with circular polarization. A simpler technique was tested that minimized variability and background intensity with linear polarization by acquiring images at multiple angles of histology slide rotation to create a composite co-registered image, permitting the optimal semi-quantitative visualization of collagen. Linear polarization imaging was performed on PSR stained artery sections. By rotating the slide at 60° intervals while maintaining illumination, polarization and exposure parameters, 6 images were acquired for each section. A composite image was created from the 6 co-registered images, and comprised of the maximum pixel intensity at each point. Images from any of the 6 rotation positions consistently showed variation in PSR signal. A composite image compensates for this variability, without loss of spatial resolution. Additionally, grayscale analysis showed an increased intensity range of 15 - 50% with a linearly polarized composite image over a circularly polarized image after background correction, indicating better SNR. This proposed technique will be applied in the development of a near infrared spectroscopy algorithm to detect vulnerable atherosclerotic plaques in vivo.

  1. Culture of dialysis fluids on nutrient-rich media for short periods at elevated temperatures underestimate microbial contamination.

    PubMed

    Pass, T; Wright, R; Sharp, B; Harding, G B

    1996-01-01

    Recommended culture methods for monitoring bacterial contamination of H2O, dialysate and bicarbonate concentrate in dialysis centers in the USA involves culturing these fluids for 48 h at 37 degrees C. A variety of media and commercial culture methods are accepted for monitoring these fluids. Over a 3-month a comparison was made between an acceptable culture method, tryptic soy agar (TSA) employing the pour plate (PP) technique at 37 degrees C for 48 h, and PP cultures on standard methods agar (SMA) and R2A agar, incubated at ambient temperature (23 degrees C) for 48, 72, 168 h. Increases in the colony counts over time occurred for all three fluids. However, counts wee greater on SMA and R2A than on TSA. The increases over the standard 48-hour TSA cultures ranged as high as 10(4) times for 23 degrees C cultures at 7 days of incubation. Endotoxin levels even in the most contaminated samples were found to be below the acceptable 5 EU/ml recommended for reprocessor water. Bacterial colonies that appeared at 48, 72 and 168 h were isolated and identified. Pseudomonas, Moraxella, Acinetobacter and CDC group VI C-2 were among some of the common bacteria isolated. This study indicates that the media utilized, the time and temperature of incubation may result in a significant underestimation of the bacterial population of water and dialysis fluids, thus potentially placing the patient at a higher risk. PMID:8785029

  2. Isolated assessment of translation or rotation severely underestimates the effects of subject motion in fMRI data.

    PubMed

    Wilke, Marko

    2014-01-01

    Subject motion has long since been known to be a major confound in functional MRI studies of the human brain. For resting-state functional MRI in particular, data corruption due to motion artefacts has been shown to be most relevant. However, despite 6 parameters (3 for translations and 3 for rotations) being required to fully describe the head's motion trajectory between timepoints, not all are routinely used to assess subject motion. Using structural (n = 964) as well as functional MRI (n = 200) data from public repositories, a series of experiments was performed to assess the impact of using a reduced parameter set (translationonly and rotationonly) versus using the complete parameter set. It could be shown that the usage of 65 mm as an indicator of the average cortical distance is a valid approximation in adults, although care must be taken when comparing children and adults using the same measure. The effect of using slightly smaller or larger values is minimal. Further, both translationonly and rotationonly severely underestimate the full extent of subject motion; consequently, both translationonly and rotationonly discard substantially fewer datapoints when used for quality control purposes ("motion scrubbing"). Finally, both translationonly and rotationonly severely underperform in predicting the full extent of the signal changes and the overall variance explained by motion in functional MRI data. These results suggest that a comprehensive measure, taking into account all available parameters, should be used to characterize subject motion in fMRI. PMID:25333359

  3. Morphological Retrospective Study of Peritoneal Biopsies from Patients with Encapsulating Peritoneal Sclerosis: Underestimated Role of Adipocytes as New Fibroblasts Lineage?

    PubMed Central

    Tooulou, Monika; Demetter, Pieter; Hamade, Anwar; Keyzer, Caroline; Nortier, Joëlle L.; Pozdzik, Agnieszka A.

    2015-01-01

    Background. Encapsulating peritoneal sclerosis (EPS) is a rare but serious complication of peritoneal dialysis (PD). Besides the endothelial-to-mesenchymal transition (EMT), recently peritoneal adipocytes emerged as a potential source of fibrosis. We performed immunohistochemistry to approach EMT and to localize peritoneal adipocytes in peritoneal biopsies from PD-related EPS patients. Material and Methods. We investigated tissue expression of podoplanin, cytokeratin AE1/AE3 (mesothelium), calretinin (adipocytes), alpha-smooth muscle actin [α-SMA] (mesenchymal cells), interstitial mononuclear cell inflammation, and neoangiogenesis (CD3, CD4, CD8, CD20, CD68, and CD31 immunostainings, resp.). Results. Three patients (1 man/2 women; 17, 64, and 39 years old, resp.) developed EPS after 21, 90, and 164 months of PD therapy. In patients with EPS, we observed (1) loss of AE1/AE3 cytokeratin+ mesothelial cells without any evidence of migration into the interstitium, (2) disappearance of adipose tissue, (3) diffuse infiltration of calretinin+ cells in the areas of submesothelial fibrosis with a huge number of α-SMA and calretinin+ fusiform cells, and (4) increased vascular density. Conclusion. We report that the involvement of EMT in peritoneal fibrosis is difficult to demonstrate and that the calretinin+ adipocytes might be an underestimated component and a new source of myofibroblasts in peritoneal remodeling during PD-related EPS. PMID:26366298

  4. Phylogenetic Relationships among NE Atlantic Plocamionida Topsent (1927) (Porifera, Poecilosclerida): Under-Estimated Diversity in Reef Ecosystems

    PubMed Central

    Reveillaud, Julie; van Soest, Rob; Derycke, Sofie; Picton, Bernard; Rigaux, Annelien; Vanreusel, Ann

    2011-01-01

    Background Small and cryptic sponges associated with cold-water coral reefs are particularly numerous and challenging to identify, but their ecological and biochemical importance is likely to compete with megabenthic specimens. Methodology/Principal Findings Here we use a combination of the standard M1M6 and I3M11 partitions of the COI fragment, partial rDNA 28S sequences and morphology to delineate small encrusting Plocamionida species. In total, 46 specimens were retrieved from seven shallow to deep-water coral locations, crossing 3,000 km along the European margins. Our work provides evidence that the Plocamionida ambigua f. tylotata and f. grandichelata can be considered valid species, whereas Plocamionida ambigua f. tornata corresponds to the species P. ambigua. Within the monophyletic group of Plocamionida, P. microcionides is shown as really divergent from the other taxa, and four putative new Plocamionida species are suggested. Conclusions/Significance This study shows that the use of molecular and morphological information in an integrative approach is a powerful tool for the identification of sponge species, and suggests that an under-estimated biodiversity of sponges occurs in cold-water coral reefs. PMID:21347368

  5. Cigar, cigarillo, and little cigar use among Canadian youth: are we underestimating the magnitude of this problem?

    PubMed

    Leatherdale, Scott T; Rios, Patricia; Elton-Marshall, Tara; Burkhalter, Robin

    2011-08-01

    Data from 29,296 students in grades 9-12 as part of the 2008-2009 Youth Smoking Survey were used to examine the prevalence of cigar, cigarillo, and little cigar use and factors associated with their use. Among Canadian youth in grades 9-12, 12.9% reported current use of cigarillos or little cigars, and 8.1% reported current use of cigars. The characteristics of youth most likely to use either cigars or cigarillos and little cigars were being male, being in grade 11 or 12, being a daily or occasional cigarette smoker, having more than $20 of weekly spending money, and having ever tried flavored tobacco. Our findings suggest that cigars, cigarillos, and little cigars are used by a substantial number of Canadian youth, many of whom do not smoke cigarettes. As such, current national prevalence estimates of youth smoking may be underestimated, and existing tobacco control prevention programs and policies may be overlooking a large population of at-risk youth. PMID:21809109

  6. Possible underestimations of risks for the environment due to unregulated emissions of biocides from households to wastewater.

    PubMed

    Wieck, Stefanie; Olsson, Oliver; Kümmerer, Klaus

    2016-09-01

    The aim of this study was to investigate the role of household products as possible sources of biocidal active substances in municipal wastewater and their regulation under the Biocidal Products Regulation (EU) 528/2012. In 131 households, we investigated the prevalence of products used to control pests, washing and cleaning agents and select personal care products with high release to wastewater. Inventories of these products were established with the help of barcode scanning. All uses of biocidal active substances were evaluated regarding their assessment under the Biocidal Products Regulation. 2963 products were scanned in total, with 48% being washing and cleaning agents, 43% personal care products and 9% products used to control pests. Biocidal active substances were found in each household. These were observed primarily in washing and cleaning agents and personal care products (90%), while only a small percentage of the observations of biocidal active substances was in biocidal products. 64% of the observations of biocidal active substances were in applications that do not fall under the Biocidal Products Regulation and are thus not subject to its environmental risk assessment. This study shows clearly that risks for the environment are underestimated because unregulated emissions to wastewater occur. It demonstrates that there are gaps in the current chemical legislation that lead to a release of substances into wastewater that were not subject to environmental risk assessment under the Biocidal Products Regulation. This is one example of the limitations of scientific risk assessment of chemicals - its complexity is immense. From our point of view, the results underline the importance of a sustainable use of the substances as this is the only way to decrease yet unidentified risks. PMID:27448707

  7. Toxicity characteristic leaching procedure over- or under-estimates leachability of lead in phosphate-amended contaminated soils.

    PubMed

    Sima, Jingke; Cao, Xinde; Zhao, Ling; Luo, Qishi

    2015-11-01

    In this study, Pb(NO3)2-, PbSO4-, or PbCO3-contaminated soils were treated with triple super phosphate (TSP) or phosphate rock (PR) and then subjected to the toxicity characteristic leaching procedure (TCLP) to assess Pb leachability. Soluble TSP resulted in the transformation of Pb into insoluble Pb phosphate precipitates in all contaminated soils, and the transformation increased with extended leaching times. Consequently, Pb concentrations in the TCLP leachates treated with TSP were reduced by 97.3-99.7% compared with the untreated soils, and Pb leaching decreased over the extraction time and did not reach equilibrium even after 96 h of extraction. Precipitation of Pb phosphate minerals in the less soluble PR-treated soil was limited, and Pb leaching was controlled by the dissolution of the Pb compounds, resulting in elevation of Pb in the TCLP leachate. Pb leaching continued to increase with time due to continuous dissolution of PbSO4 and PbCO3. The results indicated that Pb leaching is kinetically controlled by either Pb compound dissolution or phosphate mineral formation. The standard TCLP test using a designated 18 h incubation time can overestimate the leachability of Pb in soils contaminated with lead and amended with soluble TSP and underestimate the leachability of Pb in soils contaminated with Pb and amended with less soluble PR. Therefore, wide use of TCLP for assessing Pb leachability in all contaminated soils is insufficient, and development of a site-specific evaluation method is urgently needed. PMID:26275597

  8. Bicyclists overestimate their own night-time conspicuity and underestimate the benefits of retroreflective markers on the moveable joints.

    PubMed

    Wood, Joanne M; Tyrrell, Richard A; Marszalek, Ralph; Lacherez, Philippe; Carberry, Trent

    2013-06-01

    Conspicuity limitations make bicycling at night dangerous. This experiment quantified bicyclists' estimates of the distance at which approaching drivers would first recognize them. Twenty five participants (including 13 bicyclists who rode at least once per week, and 12 who rode once per month or less) cycled in place on a closed-road circuit at night-time and indicated when they were confident that an approaching driver would first recognize that a bicyclist was present. Participants wore black clothing alone or together with a fluorescent bicycling vest, a fluorescent bicycling vest with additional retroreflective tape, or the fluorescent retroreflective vest plus ankle and knee reflectors in a modified 'biomotion' configuration. The bicycle had a light mounted on the handlebars which was either static, flashing or off. Participants judged that black clothing made them least visible, retroreflective strips on the legs in addition to a retroreflective vest made them most visible and that adding retroreflective materials to a fluorescent vest provides no conspicuity benefits. Flashing bicycle lights were associated with higher conspicuity than static lights. Additionally, occasional bicyclists judged themselves to be more visible than did frequent bicyclists. Overall, bicyclists overestimated their conspicuity compared to previously collected recognition distances and underestimated the conspicuity benefits of retroreflective markings on their ankles and knees. Participants mistakenly judged that a fluorescent vest that did not include retroreflective material would enhance their night-time conspicuity. These findings suggest that bicyclists have dangerous misconceptions concerning the magnitude of the night-time conspicuity problem and the potential value of conspicuity treatments. PMID:23542135

  9. Look before You Leap: Underestimating Chinese Student History, Chinese University Setting and Chinese University Steering in Sino-British HE Joint Ventures?

    ERIC Educational Resources Information Center

    Dow, Ewan G.

    2010-01-01

    This article makes the case--in three parts--that many Anglo-Chinese university collaborations (joint ventures) to date have seriously underestimated Chinese (student) history, the Chinese university setting and Chinese national governmental steering as part of the process of "glocalisation". Recent turbulence in this particular HE collaborative…

  10. Overestimation and Underestimation: Adolescents' Weight Perception in Comparison to BMI-Based Weight Status and How It Varies across Socio-Demographic Factors

    ERIC Educational Resources Information Center

    Park, Eunkyung

    2011-01-01

    Background: Weight perception has been studied with a limited focus on "feeling overweight." This study, using a more inclusive definition of overestimation and underestimation, examines adolescents' weight perception focusing on how accurate it is in relation to body mass index (BMI)-based weight status and how it varies across socio-demographic…

  11. General Dentist

    MedlinePlus

    ... to your desktop! more... What Is a General Dentist? Article Chapters What Is a General Dentist? General ... Reviewed: January 2012 ?xml:namespace> Related Articles: General Dentists FAGD and MAGD: What Do These Awards Mean? ...

  12. Substantial Underestimation of Post-harvest Burning Emissions in East China as Seen by Multi-species Space Observations

    NASA Astrophysics Data System (ADS)

    Stavrakou, T.; Muller, J. F.; Bauwens, M.; De Smedt, I.; Lerot, C.; Van Roozendael, M.

    2015-12-01

    Crop residue burning is an important contributor to global biomass burning. In the North China Plain, one of the largest and densely populated world plains, post-harvest crop burning is a common agricultural management practice, allowing for land clearing from residual straw and preparation for the subsequent crop cultivation. The most extensive crop fires occur in the North China Plain in June after the winter wheat comes to maturity, and have been blamed for spikes in air pollution leading to serious health problems. Estimating harvest season burning emissions is therefore of primary importance to assess air quality and define best policies for its improvement in this sensitive region. Bottom-up approaches, either based on crop production and emission factors, or on satellite burned area and fire radiative power products, have been adopted so far, however, these methods crucially depend, among other assumptions, on the satellite skill to detect small fires, and could lead to underestimation of the actual emissions. The flux inversion of atmospheric observations is an alternative, independent approach for inferring the emissions from crop fires. Satellite column observations of formaldehyde (HCHO) exhibit a strong peak over the North China Plain in June, resulting from enhanced pyrogenic emissions of a large suite of volatile organic compounds (VOCs), precursors of HCHO. We use vertical columns of formaldehyde retrieved from the OMI instrument between 2005 and 2012 as constraints in an adjoint inversion scheme built on IMAGESv2 CTM, and perform the optimization of biogenic, pyrogenic, and anthropogenic emission parameters at the model resolution. We investigate the interannual variability of the top-down source, quantify its importance for the atmospheric composition on the regional scale, and explore its uncertainties. The OMI-based crop burning source is compared with the corresponding anthropogenic flux in the North China Plain, and is evaluated against HCHO

  13. How systematic age underestimation can impede understanding of fish population dynamics: Lessons learned from a Lake Superior cisco stock

    USGS Publications Warehouse

    Yule, D.L.; Stockwell, J.D.; Black, J.A.; Cullis, K.I.; Cholwek, G.A.; Myers, J.T.

    2008-01-01

    Systematic underestimation of fish age can impede understanding of recruitment variability and adaptive strategies (like longevity) and can bias estimates of survivorship. We suspected that previous estimates of annual survival (S; range = 0.20-0.44) for Lake Superior ciscoes Coregonus artedi developed from scale ages were biased low. To test this hypothesis, we estimated the total instantaneous mortality rate of adult ciscoes from the Thunder Bay, Ontario, stock by use of cohort-based catch curves developed from commercial gill-net catches and otolith-aged fish. Mean S based on otolith ages was greater for adult females (0.80) than for adult males (0.75), but these differences were not significant. Applying the results of a study of agreement between scale and otolith ages, we modeled a scale age for each otolith-aged fish to reconstruct catch curves. Using modeled scale ages, estimates of S (0.42 for females, 0.36 for males) were comparable with those reported in past studies. We conducted a November 2005 acoustic and midwater trawl survey to estimate the abundance of ciscoes when the fish were being harvested for roe. Estimated exploitation rates were 0.085 for females and 0.025 for males, and the instantaneous rates of fishing mortality were 0.089 for females and 0.025 for males. The instantaneous rates of natural mortality were 0.131 and 0.265 for females and males, respectively. Using otolith ages, we found that strong year-classes at large during November 2005 were caught in high numbers as age-1 fish in previous annual bottom trawl surveys, whereas weak or absent year-classes were not. For decades, large-scale fisheries on the Great Lakes were allowed to operate because ciscoes were assumed to be short lived and to have regular recruitment. We postulate that the collapse of these fisheries was linked in part to a misunderstanding of cisco biology driven by scale-ageing error. ?? Copyright by the American Fisheries Society 2008.

  14. On underestimation of global vulnerability to tree mortality and forest die-off from hotter drought in the Anthropocene

    USGS Publications Warehouse

    Allen, Craig D.; Breshears, David D.; McDowell, Nathan G.

    2015-01-01

    hotter drought, consistent with fundamental physiology; (5) shorter droughts occur more frequently than longer droughts and can become lethal under warming, increasing the frequency of lethal drought nonlinearly; and (6) mortality happens rapidly relative to growth intervals needed for forest recovery. These high-confidence drivers, in concert with research supporting greater vulnerability perspectives, support an overall viewpoint of greater forest vulnerability globally. We surmise that mortality vulnerability is being discounted in part due to difficulties in predicting threshold responses to extreme climate events. Given the profound ecological and societal implications of underestimating global vulnerability to hotter drought, we highlight urgent challenges for research, management, and policy-making communities.

  15. Estimating trematode prevalence in snail hosts using a single-step duplex PCR: how badly does cercarial shedding underestimate infection rates?

    PubMed Central

    2014-01-01

    Background Trematode communities often consist of different species exploiting the same host population, with two or more trematodes sometimes co-occuring in the same host. A commonly used diagnostic method to detect larval trematode infections in snails has been based on cercarial shedding, though it is often criticized as inaccurate. In the present study we compare infection prevalences determined by cercarial emission with those determined, for the first time, by molecular methods, allowing us to quantify the underestimation of single and double infections based on cercarial emission. We thus developed a duplex PCR for two host-parasite systems, to specifically differentiate between single and double infections. The Ebro samples include two morphologically similar opecoelids, whereas the Otago samples include two morphologically different larval trematodes. Methods Snails were screened for infections by incubating them individually to induce cercarial emission, thus determining infection following the “classical” detection method. Snail tissue was then removed and fixed for the duplex PCR. After obtaining ITS rDNA sequences, four species-specific primers were designed for each snail-trematode system, and duplex PCR prevalence was determined for each sample. Results from both methods were statistically compared using the McNemar’s Chi-squared test and Cohen’s Kappa Statistic for agreement between outcomes. Results Overall infection prevalences determined by duplex PCR were consistently and substantially higher than those based on cercarial shedding: among Ebro samples, between 17.9% and 60.1% more snails were found infected using the molecular method, whereas in the Otago samples, the difference was between 9.9% and 20.6%. Kappa values generally indicated a fair to substantial agreement between both detection methods, showing a lower agreement for the Ebro samples. Conclusions We demonstrate that molecular detection of single and double infections by

  16. Gastrointestinal hemorrhage: evaluation with MDCT.

    PubMed

    Soto, Jorge A; Park, Seong Ho; Fletcher, Joel G; Fidler, Jeff L

    2015-06-01

    Gastrointestinal (GI) bleeding is a common medical problem, with high associated morbidity and mortality. The clinical presentation of gastrointestinal hemorrhage varies with the location of the bleeding source, the intensity of the bleed, and the presence of comorbidities that affect the ability to tolerate blood loss. Conventional endoscopic examinations are usually the initial diagnostic tests in patients presenting with overt gastrointestinal hemorrhage. However, implementation of upper tract endoscopy and colonoscopy in the emergency setting can be challenging due to inconsistent availability of the service and difficulties in achieving adequate colonic cleansing in emergent situations. Thus, imaging tests are often relied upon to establish the location and the cause of bleeding, either for initial diagnosis or after non-revealing upper and lower tract endoscopies ("obscure" bleeding). This article discusses the imaging evaluation of patients with gastrointestinal bleeding and reviews the imaging appearance of the most common causes, taking into account the two most relevant clinical presentations: overt bleeding and obscure bleeding. PMID:25637128

  17. Antialiasing backprojection for helical MDCT.

    PubMed

    Mori, I

    2008-03-01

    Helical CTs are well known to suffer from aliasing artifacts because of their finite longitudinal sampling pitch. The artifact pattern is typically strong streaks from bone edges in clinical images. Especially in the case of multidetector row CT, the artifact resulting from longitudinal aliasing is often called a windmill artifact because the visible streaks form a windmill pattern when the object is of a particular shape. The scan must be performed using a very thin slice thickness, i.e., fine sampling in the longitudinal direction, with a longer scan time to mitigate this aliasing artifact. Some elaborate longitudinal interpolation methods to remediate longitudinal aliasing have been proposed, but they have not been successful in practice despite their theoretical importance. A periodic swing of the focal spot in the longitudinal direction, a so-called z-flying focal spot, was introduced recently to achieve finer sampling. Although it is a useful technique, some important deficiencies exist: It is sufficiently effective only near the isocenter and is difficult to apply to a scan using a thick slice thickness, even though longitudinal aliasing is more serious at the thicker scan. In this paper, the author addresses the nature of interlaced (or unequally spaced) sampling and derives a new principle of data treatment that can suppress the aliased spectra selectively. According to this principle, the common practice of image reconstruction, which backprojects data along the original sampling ray path, is never the best choice. The author proposes a new scheme of backprojection, which involves the longitudinal shift of projection data. A proper choice of longitudinal shift for backprojection provides effective and selective suppression of aliased spectra, with retention of the original frequency spectrum depending on the level of focus swing. With this shifted backprojection, the swing of focus can be made much smaller than for a conventional z-flying focal spot. The required amount of shift for backprojection is position dependent. Nevertheless, its implementation in the reconstruction process can be achieved simply by relocating the x-ray source and detector assembly from positions of actual scanning. Through simulation, the combination of shifted backprojection and the small swing of focus is evaluated. Results confirm that the artifact attributable to longitudinal aliasing is well suppressed in the entire field of view, whereas the penalty on the slice sensitivity profile (or longitudinal resolution) can be kept minimal. Moreover, this method solves other deficiencies of z-flying focus, such as inapplicability to scans with a thicker slice thickness. PMID:18404941

  18. Numerical study identifying the factors causing the significant underestimation of the specific discharge estimated using the modified integral pumping test method in a laboratory experiment

    NASA Astrophysics Data System (ADS)

    Sun, Kerang

    2015-09-01

    A three-dimensional finite element model is constructed to simulate the experimental conditions presented in a paper published in this journal [Goltz et al., 2009. Validation of two innovative methods to measure contaminant mass flux in groundwater. Journal of Contaminant Hydrology 106 (2009) 51-61] where the modified integral pumping test (MIPT) method was found to significantly underestimate the specific discharge in an artificial aquifer. The numerical model closely replicates the experimental configuration with explicit representation of the pumping well column and skin, allowing for the model to simulate the wellbore flow in the pumping well as an integral part of the porous media flow in the aquifer using the equivalent hydraulic conductivity approach. The equivalent hydraulic conductivity is used to account for head losses due to friction within the wellbore of the pumping well. Applying the MIPT method on the model simulated piezometric heads resulted in a specific discharge that underestimates the true specific discharge in the experimental aquifer by 18.8%, compared with the 57% underestimation of mass flux by the experiment reported by Goltz et al. (2009). Alternative simulation shows that the numerical model is capable of approximately replicating the experiment results when the equivalent hydraulic conductivity is reduced by an order of magnitude, suggesting that the accuracy of the MIPT estimation could be improved by expanding the physical meaning of the equivalent hydraulic conductivity to account for other factors such as orifice losses in addition to frictional losses within the wellbore. Numerical experiments also show that when applying the MIPT method to estimate hydraulic parameters, use of depth-integrated piezometric head instead of the head near the pump intake can reduce the estimation error resulting from well losses, but not the error associated with the well not being fully screened.

  19. Numerical study identifying the factors causing the significant underestimation of the specific discharge estimated using the modified integral pumping test method in a laboratory experiment.

    PubMed

    Sun, Kerang

    2015-09-01

    A three-dimensional finite element model is constructed to simulate the experimental conditions presented in a paper published in this journal [Goltz et al., 2009. Validation of two innovative methods to measure contaminant mass flux in groundwater. Journal of Contaminant Hydrology 106 (2009) 51-61] where the modified integral pumping test (MIPT) method was found to significantly underestimate the specific discharge in an artificial aquifer. The numerical model closely replicates the experimental configuration with explicit representation of the pumping well column and skin, allowing for the model to simulate the wellbore flow in the pumping well as an integral part of the porous media flow in the aquifer using the equivalent hydraulic conductivity approach. The equivalent hydraulic conductivity is used to account for head losses due to friction within the wellbore of the pumping well. Applying the MIPT method on the model simulated piezometric heads resulted in a specific discharge that underestimates the true specific discharge in the experimental aquifer by 18.8%, compared with the 57% underestimation of mass flux by the experiment reported by Goltz et al. (2009). Alternative simulation shows that the numerical model is capable of approximately replicating the experiment results when the equivalent hydraulic conductivity is reduced by an order of magnitude, suggesting that the accuracy of the MIPT estimation could be improved by expanding the physical meaning of the equivalent hydraulic conductivity to account for other factors such as orifice losses in addition to frictional losses within the wellbore. Numerical experiments also show that when applying the MIPT method to estimate hydraulic parameters, use of depth-integrated piezometric head instead of the head near the pump intake can reduce the estimation error resulting from well losses, but not the error associated with the well not being fully screened. PMID:26210034

  20. A Molecular Genetic Timescale for the Diversification of Autotrophic Stramenopiles (Ochrophyta): Substantive Underestimation of Putative Fossil Ages

    PubMed Central

    Brown, Joseph W.; Sorhannus, Ulf

    2010-01-01

    Background Stramenopiles constitute a large and diverse eukaryotic clade that is currently poorly characterized from both phylogenetic and temporal perspectives at deeper taxonomic levels. To better understand this group, and in particular the photosynthetic stramenopiles (Ochrophyta), we analyzed sequence data from 135 taxa representing most major lineages. Our analytical approach utilized several recently developed methods that more realistically model the temporal evolutionary process. Methodology/Principal Findings Phylogenetic reconstruction employed a Bayesian joint rate- and pattern-heterogeneity model to reconstruct the evolutionary history of these taxa. Inferred phylogenetic resolution was generally high at all taxonomic levels, sister-class relationships in particular receiving good statistical support. A signal for heterotachy was detected in clustered portions of the tree, although this does not seem to have had a major influence on topological inference. Divergence time estimates, assuming a lognormally-distributed relaxed molecular clock while accommodating topological uncertainty, were broadly congruent over alternative temporal prior distributions. These data suggest that Ochrophyta originated near the Proterozoic-Phanerozoic boundary, diverging from their sister-taxon Oomycota. The evolution of the major ochrophyte lineages appears to have proceeded gradually thereafter, with most lineages coming into existence by ∼200 million years ago. Conclusions/Significance The evolutionary timescale of the autotrophic stramenopiles reconstructed here is generally older than previously inferred from molecular clocks. However, this more ancient timescale nevertheless casts serious doubt on the taxonomic validity of putative xanthophyte/phaeophyte fossils from the Proterozoic, which predate by as much as a half billion years or more the age suggested by our molecular genetic data. If these fossils truly represent crown stramenopile lineages, then this would

  1. Haemoglobin J-Baltimore can be detected by HbA1c electropherogram but with underestimated HbA1c value

    PubMed Central

    Brunel, Valéry; Lahary, Agnčs; Chagraoui, Abdeslam; Thuillez, Christian

    2016-01-01

    Glycated haemoglobin (HbA1c) is considered the gold standard for assessing diabetes compensation and treatment. In addition, fortuitous detection of haemoglobin variants during HbA1c measurement is not rare. Recently, two publications reported different conclusions on accuracy of HbA1c value using capillary electrophoresis method in presence of haemoglobin J-Baltimore (HbJ).
Here we describe the fortuitous detection of unknown HbJ using capillary electrophoresis for measurement of HbA1c. A patient followed for gestational diabetes in our laboratory presented unknown haemoglobin on Capillarys 2 Flex Piercing analyser which was identified as HbJ. HbJ is not associated with haematological abnormalities. High Performance Liquid Chromatography methods are known to possibly underestimate HbA1c value in the presence of this variant. This variant and its glycated form are clearly distinguished on electropherogram but HbJ was responsible for underestimating the true area of HbA1c.
Capillary electrophoresis is a good method for detecting HbJ but does not seem suitable for evaluation of HbA1C value in patients in presence of HbJ variant. PMID:27346969

  2. Causes of systematic over- or underestimation of low streamflows by use of index-streamgage approaches in the United States

    USGS Publications Warehouse

    Eng, K.; Kiang, J.E.; Chen, Y.-Y.; Carlisle, D.M.; Granato, G.E.

    2011-01-01

    Low-flow characteristics can be estimated by multiple linear regressions or the index-streamgage approach. The latter transfers streamflow information from a hydrologically similar, continuously gaged basin ('index streamgage') to one with a very limited streamflow record, but often results in biased estimates. The application of the index-streamgage approach can be generalized into three steps: (1) selection of streamflow information of interest, (2) definition of hydrologic similarity and selection of index streamgage, and (3) application of an information-transfer approach. Here, we explore the effects of (1) the range of streamflow values, (2) the areal density of streamgages, and (3) index-streamgage selection criteria on the bias of three information-transfer approaches on estimates of the 7-day, 10-year minimum streamflow (Q7, 10). The three information-transfer approaches considered are maintenance of variance extension, base-flow correlation, and ratio of measured to concurrent gaged streamflow (Q-ratio invariance). Our results for 1120 streamgages throughout the United States suggest that only a small portion of the total bias in estimated streamflow values is explained by the areal density of the streamgages and the hydrologic similarity between the two basins. However, restricting the range of streamflow values used in the index-streamgage approach reduces the bias of estimated Q7, 10 values substantially. Importantly, estimated Q7, 10 values are heavily biased when the observed Q7, 10 values are near zero. Results of the analysis also showed that Q7, 10 estimates from two of the three index-streamgage approaches have lower root-mean-square error values than estimates derived from multiple regressions for the large regions considered in this study.

  3. Estimating fitness consequences of dispersal: a road to 'know-where'? Non-random dispersal and the underestimation of dispersers' fitness.

    PubMed

    Doligez, Blandine; Pärt, Tomas

    2008-11-01

    1. Many studies investigating fitness correlates of dispersal in vertebrates report dispersers to have lower fitness than philopatric individuals. However, if dispersers are more likely to produce dispersing young or are more likely to disperse again in the next year(s) than philopatric individuals, there is a risk that fitness estimates based on local adult survival and local recruitment will be underestimated for dispersers. 2. We review the available empirical evidence on parent-offspring resemblance and individual lifelong consistency in dispersal behaviour, and relate these studies to recent studies of fitness correlates of dispersal in vertebrates. 3. Of the 12 studies testing directly for parent-offspring resemblance in dispersal propensity, five report a significant resemblance. The average effect size (r) of parent-offspring resemblance in dispersal was 0.15 [95% confidence interval (CI) = 0.07-0.22], with no difference between the sexes (average weighted effect size of 0.12 (0.08-0.16) and 0.16 (0.11-0.20) for females and males, respectively). Only three studies report data on within-individual consistency in dispersal propensity, of which two suggest dispersers to be more likely to disperse again. 4. To assess the magnitude of fitness underestimation expected for dispersing individuals depending on the heritability of dispersal distance and study area size, we used a simulation approach. Even when study area size is 10 times the mean dispersal distance, local recruitment per breeding event may be underestimated by 4-10%, generating a potential difference of 4-60% in average lifetime production of recruits between dispersing and philopatric individuals, with larger differences in long-lived species. 5. Estimates of both fitness correlates of dispersal and parent-offspring resemblance or within-individual consistency in dispersal behaviour have been reported for 11 species. Although some comparisons suggest genuine differences in fitness components between

  4. Auras in generalized epilepsy

    PubMed Central

    Carlson, Chad; Bluvstein, Judith; Chong, Derek J.; Friedman, Daniel; Kirsch, Heidi E.

    2014-01-01

    Objective: We studied the frequency of auras in generalized epilepsy (GE) using a detailed semistructured diagnostic interview. Methods: In this cross-sectional study, participants with GE were drawn from the Epilepsy Phenome/Genome Project (EPGP). Responses to the standardized diagnostic interview regarding tonic-clonic (grand mal) seizures were then examined. This questionnaire initially required participants to provide their own description of any subjective phenomena before their “grand mal seizures.” Participants who provided answers to these questions were considered to have an aura. All participants were then systematically queried regarding a list of specific symptoms occurring before grand mal seizures, using structured (closed-ended) questions. Results: Seven hundred ninety-eight participants with GE were identified, of whom 530 reported grand mal seizures. Of these, 112 (21.3%) reported auras in response to the open-ended question. Analysis of responses to the closed-ended questions suggested that 341 participants (64.3%) experienced at least one form of aura. Conclusions: Auras typically associated with focal epilepsy were reported by a substantial proportion of EPGP subjects with GE. This finding may support existing theories of cortical and subcortical generators of GE with variable spread patterns. Differences between responses to the open-ended question and closed-ended questions may also reflect clinically relevant variation in patient responses to history-taking and surveys. Open-ended questions may underestimate the prevalence of specific types of auras and may be in part responsible for the underrecognition of auras in GE. In addition, structured questions may influence participants, possibly leading to a greater representation of symptoms. PMID:25230998

  5. Surgeon General

    MedlinePlus

    ... the Conversation → Step it Up! Help Make Our Communities Walkable YouTube embedded video: https://www.youtube-nocookie. ... Surgeon General Vivek H. Murthy to make our communities more walkable. Watch the video . See All Videos → ...

  6. General anesthesia

    MedlinePlus

    General anesthesia is treatment with certain medicines that puts you into a deep sleep so you do not feel ... doctor called an anesthesiologist will give you the anesthesia. Sometimes, a certified and registered nurse anesthetist will ...

  7. Pitfalls of the MTT assay: Direct and off-target effects of inhibitors can result in over/underestimation of cell viability.

    PubMed

    Stepanenko, A A; Dmitrenko, V V

    2015-12-15

    The MTT assay (to a less degree MTS, XTT or WST) is a widely exploited approach for measuring cell viability/drug cytotoxicity. MTT reduction occurs throughout a cell and can be significantly affected by a number of factors, including metabolic and energy perturbations, changes in the activity of oxidoreductases, endo-/exocytosis and intracellular trafficking. Over/underestimation of cell viability by the MTT assay may be due to both adaptive metabolic and mitochondrial reprogramming of cells subjected to drug treatment-mediated stress and inhibitor off-target effects. Previously, imatinib, rottlerin, ursolic acid, verapamil, resveratrol, genistein nanoparticles and some polypeptides were shown to interfere with MTT reduction rate resulting in inconsistent results between the MTT assay and alternative assays. Here, to test the under/overestimation of viability by the MTT assay, we compared results derived from the MTT assay with the trypan blue exclusion assay after treatment of glioblastoma U251, T98G and C6 cells with three widely used inhibitors with the known direct and side effects on energy and metabolic homeostasis - temozolomide (TMZ), a DNA-methylating agent, temsirolimus (TEM), an inhibitor of mTOR kinase, and U0126, an inhibitor of MEK1/2 kinases. Inhibitors were applied shortly as in IC50 evaluating studies or long as in studies focusing on drug resistance acquisition. We showed that over/underestimation of cell viability by the MTT assay and its significance depends on a cell line, a time point of viability measurement and other experimental parameters. Furthermore, we provided a comprehensive survey of factors that should be accounted in the MTT assay. To avoid result misinterpretation, supplementation of the tetrazolium salt-based assays with other non-metabolic assays is recommended. PMID:26260013

  8. A Trans-Amazonian Screening of mtDNA Reveals Deep Intraspecific Divergence in Forest Birds and Suggests a Vast Underestimation of Species Diversity

    PubMed Central

    Milá, Borja; Tavares, Erika S.; Muñoz Saldaña, Alberto; Karubian, Jordan; Smith, Thomas B.; Baker, Allan J.

    2012-01-01

    The Amazonian avifauna remains severely understudied relative to that of the temperate zone, and its species richness is thought to be underestimated by current taxonomy. Recent molecular systematic studies using mtDNA sequence reveal that traditionally accepted species-level taxa often conceal genetically divergent subspecific lineages found to represent new species upon close taxonomic scrutiny, suggesting that intraspecific mtDNA variation could be useful in species discovery. Surveys of mtDNA variation in Holarctic species have revealed patterns of variation that are largely congruent with species boundaries. However, little information exists on intraspecific divergence in most Amazonian species. Here we screen intraspecific mtDNA genetic variation in 41 Amazonian forest understory species belonging to 36 genera and 17 families in 6 orders, using 758 individual samples from Ecuador and French Guiana. For 13 of these species, we also analyzed trans-Andean populations from the Ecuadorian Chocó. A consistent pattern of deep intraspecific divergence among trans-Amazonian haplogroups was found for 33 of the 41 taxa, and genetic differentiation and genetic diversity among them was highly variable, suggesting a complex range of evolutionary histories. Mean sequence divergence within families was the same as that found in North American birds (13%), yet mean intraspecific divergence in Neotropical species was an order of magnitude larger (2.13% vs. 0.23%), with mean distance between intraspecific lineages reaching 3.56%. We found no clear relationship between genetic distances and differentiation in plumage color. Our results identify numerous genetically and phenotypically divergent lineages which may result in new species-level designations upon closer taxonomic scrutiny and thorough sampling, although lineages in the tropical region could be older than those in the temperate zone without necessarily representing separate species. In-depth phylogeographic surveys

  9. Underestimation of Risk of a BRCA1 or BRCA2 Mutation in Women With High-Grade Serous Ovarian Cancer by BRCAPRO: A Multi-Institution Study

    PubMed Central

    Daniels, Molly S.; Babb, Sheri A.; King, Robin H.; Urbauer, Diana L.; Batte, Brittany A.L.; Brandt, Amanda C.; Amos, Christopher I.; Buchanan, Adam H.; Mutch, David G.; Lu, Karen H.

    2014-01-01

    Purpose Identification of the 10% to 15% of patients with ovarian cancer who have germline BRCA1 or BRCA2 mutations is important for management of both patients and relatives. The BRCAPRO model, which estimates mutation likelihood based on personal and family cancer history, can inform genetic testing decisions. This study's purpose was to assess the accuracy of BRCAPRO in women with ovarian cancer. Methods BRCAPRO scores were calculated for 589 patients with ovarian cancer referred for genetic counseling at three institutions. Observed mutations were compared with those predicted by BRCAPRO. Analysis of variance was used to assess factors impacting BRCAPRO accuracy. Results One hundred eighty (31%) of 589 patients with ovarian cancer tested positive. At BRCAPRO scores less than 40%, more mutations were observed than expected (93 mutations observed v 34.1 mutations expected; P < .001). If patients with BRCAPRO scores less than 10% had not been tested, 51 (28%) of 180 mutations would have been missed. BRCAPRO underestimated the risk for high-grade serous ovarian cancers but overestimated the risk for other histologies (P < .001), underestimation increased as age at diagnosis decreased (P = .02), and model performance varied by institution (P = .02). Conclusion Patients with ovarian cancer classified as low risk by BRCAPRO are more likely to test positive than predicted. The risk of a mutation in patients with low BRCAPRO scores is high enough to warrant genetic testing. This study demonstrates that assessment of family history by a validated model cannot effectively target testing to a high-risk ovarian cancer patient population, which strongly supports the recommendation to offer BRCA1/BRCA2 genetic testing to all patients with high-grade serous ovarian cancer regardless of family history. PMID:24638001

  10. A trans-Amazonian screening of mtDNA reveals deep intraspecific divergence in forest birds and suggests a vast underestimation of species diversity.

    PubMed

    Milá, Borja; Tavares, Erika S; Muñoz Saldaña, Alberto; Karubian, Jordan; Smith, Thomas B; Baker, Allan J

    2012-01-01

    The Amazonian avifauna remains severely understudied relative to that of the temperate zone, and its species richness is thought to be underestimated by current taxonomy. Recent molecular systematic studies using mtDNA sequence reveal that traditionally accepted species-level taxa often conceal genetically divergent subspecific lineages found to represent new species upon close taxonomic scrutiny, suggesting that intraspecific mtDNA variation could be useful in species discovery. Surveys of mtDNA variation in Holarctic species have revealed patterns of variation that are largely congruent with species boundaries. However, little information exists on intraspecific divergence in most Amazonian species. Here we screen intraspecific mtDNA genetic variation in 41 Amazonian forest understory species belonging to 36 genera and 17 families in 6 orders, using 758 individual samples from Ecuador and French Guiana. For 13 of these species, we also analyzed trans-Andean populations from the Ecuadorian Chocó. A consistent pattern of deep intraspecific divergence among trans-Amazonian haplogroups was found for 33 of the 41 taxa, and genetic differentiation and genetic diversity among them was highly variable, suggesting a complex range of evolutionary histories. Mean sequence divergence within families was the same as that found in North American birds (13%), yet mean intraspecific divergence in Neotropical species was an order of magnitude larger (2.13% vs. 0.23%), with mean distance between intraspecific lineages reaching 3.56%. We found no clear relationship between genetic distances and differentiation in plumage color. Our results identify numerous genetically and phenotypically divergent lineages which may result in new species-level designations upon closer taxonomic scrutiny and thorough sampling, although lineages in the tropical region could be older than those in the temperate zone without necessarily representing separate species. In-depth phylogeographic surveys

  11. Focusing on fast food restaurants alone underestimates the relationship between neighborhood deprivation and exposure to fast food in a large rural area

    PubMed Central

    2011-01-01

    Background Individuals and families are relying more on food prepared outside the home as a source for at-home and away-from-home consumption. Restricting the estimation of fast-food access to fast-food restaurants alone may underestimate potential spatial access to fast food. Methods The study used data from the 2006 Brazos Valley Food Environment Project (BVFEP) and the 2000 U.S. Census Summary File 3 for six rural counties in the Texas Brazos Valley region. BVFEP ground-truthed data included identification and geocoding of all fast-food restaurants, convenience stores, supermarkets, and grocery stores in study area and on-site assessment of the availability and variety of fast-food lunch/dinner entrées and side dishes. Network distance was calculated from the population-weighted centroid of each census block group to all retail locations that marketed fast food (n = 205 fast-food opportunities). Results Spatial access to fast-food opportunities (FFO) was significantly better than to traditional fast-food restaurants (FFR). The median distance to the nearest FFO was 2.7 miles, compared with 4.5 miles to the nearest FFR. Residents of high deprivation neighborhoods had better spatial access to a variety of healthier fast-food entrée and side dish options than residents of low deprivation neighborhoods. Conclusions Our analyses revealed that identifying fast-food restaurants as the sole source of fast-food entrées and side dishes underestimated neighborhood exposure to fast food, in terms of both neighborhood proximity and coverage. Potential interventions must consider all retail opportunities for fast food, and not just traditional FFR. PMID:21266055

  12. Sampling in Atypical Endometrial Hyperplasia: Which Method Results in the Lowest Underestimation of Endometrial Cancer? A Systematic Review and Meta-analysis.

    PubMed

    Bourdel, Nicolas; Chauvet, Pauline; Tognazza, Enrica; Pereira, Bruno; Botchorishvili, Revaz; Canis, Michel

    2016-01-01

    Our objective was to identify the most accurate method of endometrial sampling for the diagnosis of complex atypical hyperplasia (CAH), and the related risk of underestimation of endometrial cancer. We conducted a systematic literature search in PubMed and EMBASE (January 1999-September 2013) to identify all registered articles on this subject. Studies were selected with a 2-step method. First, titles and abstracts were analyzed by 2 reviewers, and 69 relevant articles were selected for full reading. Then, the full articles were evaluated to determine whether full inclusion criteria were met. We selected 27 studies, taking into consideration the comparison between histology of endometrial hyperplasia obtained by diagnostic tests of interest (uterine curettage, hysteroscopically guided biopsy, or hysteroscopic endometrial resection) and subsequent results of hysterectomy. Analysis of the studies reviewed focused on 1106 patients with a preoperative diagnosis of atypical endometrial hyperplasia. The mean risk of finding endometrial cancer at hysterectomy after atypical endometrial hyperplasia diagnosed by uterine curettage was 32.7% (95% confidence interval [CI], 26.2-39.9), with a risk of 45.3% (95% CI, 32.8-58.5) after hysteroscopically guided biopsy and 5.8% (95% CI, 0.8-31.7) after hysteroscopic resection. In total, the risk of underestimation of endometrial cancer reaches a very high rate in patients with CAH using the classic method of evaluation (i.e., uterine curettage or hysteroscopically guided biopsy). This rate of underdiagnosed endometrial cancer leads to the risk of inappropriate surgical procedures (31.7% of tubal conservation in the data available and no abdominal exploration in 24.6% of the cases). Hysteroscopic resection seems to reduce the risk of underdiagnosed endometrial cancer. PMID:27058769

  13. [Arcobacter - an underestimated zoonotic pathogen?].

    PubMed

    Hänel, Ingrid; Tomaso, Herbert; Neubauer, Heinrich

    2016-06-01

    The relevance for public health of the agent Arcobacter is mostly unclear despite of an increasing number of studies. Recent evidence shows that especially Arcobacter (A.) butzleri but also A. cryaerophilus and A. skirrowii may be involved in human enteric diseases. However, little is currently known about pathogenicity or potential virulence factors. Livestock animals, particularly poultry and pigs, might be a significant reservoir of Arcobacter spp. Furthermore, Arcobacter spp. could be isolated from retail raw meat products of these animals as well as from drinking water. There are currently no standardized isolation and detection methods to collect comparable data. Further studies and efforts of both human and veterinary medicine are needed to elucidate prevalence, epidemiology, the pathogenic role and potential virulence factors of Arcobacter spp. These data are the necessary basis for further risk assessment. PMID:27177896

  14. Severe scurvy: an underestimated disease.

    PubMed

    Levavasseur, M; Becquart, C; Pape, E; Pigeyre, M; Rousseaux, J; Staumont-Sallé, D; Delaporte, E

    2015-09-01

    Scurvy is one of the oldest diseases in human history. Nowadays, although scurvy tends to become a forgotten disease in developed country, rare cases still occur, especially in people undergoing extreme diet, old people or children with poor diet and patients with malabsorption. We describe three cases of scurvy. The first case is a patient diagnosed with Crohn's disease, the second one is in a context of anorexia nervosa and drug addiction, and the third case is in a context of social isolation. Early recognition of scurvy can be difficult because symptoms may appear nonspecific and can mimic more common conditions. In any patient with spontaneous hematoma and purpura, in the context of nutritional disorder, scurvy should be systematically considered. As this disease can lead to severe complications, such as bone pain, heart failure or gastrointestinal symptoms, nothing should delay vitamin C supplementation, which is a simple and rapidly effective treatment. PMID:26081492

  15. [Lipoid pneumonia - an underestimated syndrome].

    PubMed

    Schwaiblmair, M; Berghaus, T; Haeckel, T; Wagner, T; Scheidt, W von

    2010-01-01

    Lipoid pneumonia, first described by Laughlen 1925 may be classified as endogenous or exogenous. The endogenous form is seen when fat is deposited into the lung tissue. It is usually associated with proximal obstructive lesions, necrotic tissue after radio- or chemotherapy, with lipid storage disease or hyperlipidemia . Exogenous lipoid pneumonia results from inhaling or aspirating animal, vegetable or mineral oil. There are usually some underlying neurological defects or esophageal abnormalities. Patients may present with cough, sputum, hemoptysis and chest pain or may be asymptomatic. There is no classic chest film appearance: it may appear as diffuse airspace infiltration or localized consolidation simulating tumour. Computed tomography is diagnostically helpful and shows hypodense areas measuring from -100 to - 30 Hounsfield units. Bronchoscopic biopsies are mandatory for histological confirmation of the diagnosis. Treatment of exogenous lipoid pneumonia has always been conservative by discontinuing the use of oil, correction of underlying defects that may favor aspiration and treatment of intercurrent pneumonia. Other measures, for example corticosteroid therapy, are of uncertain benefit. Complications of lipoid pneumonia that worsen prognosis are recurrent bacterial pneumonias including nontuberculous mycobacteria or aspergillus, or lung cancer that has developed in areas of pre-existing exogenous lipoid pneumonia. PMID:20024881

  16. Generalized Parabolas

    ERIC Educational Resources Information Center

    Joseph, Dan; Hartman, Gregory; Gibson, Caleb

    2011-01-01

    In this article we explore the consequences of modifying the common definition of a parabola by considering the locus of all points equidistant from a focus and (not necessarily linear) directrix. The resulting derived curves, which we call "generalized parabolas," are often quite beautiful and possess many interesting properties. We show that…

  17. The importance of associations with saprotrophic non-Rhizoctonia fungi among fully mycoheterotrophic orchids is currently under-estimated: novel evidence from sub-tropical Asia

    PubMed Central

    Lee, Yung-I; Yang, Chih-Kai; Gebauer, Gerhard

    2015-01-01

    Background and Aims Most fully mycoheterotrophic (MH) orchids investigated to date are mycorrhizal with fungi that simultaneously form ectomycorrhizas with forest trees. Only a few MH orchids are currently known to be mycorrhizal with saprotrophic, mostly wood-decomposing, fungi instead of ectomycorrhizal fungi. This study provides evidence that the importance of associations between MH orchids and saprotrophic non-Rhizoctonia fungi is currently under-estimated. Methods Using microscopic techniques and molecular approaches, mycorrhizal fungi were localized and identified for seven MH orchid species from four genera and two subfamilies, Vanilloideae and Epidendroideae, growing in four humid and warm sub-tropical forests in Taiwan. Carbon and nitrogen stable isotope natural abundances of MH orchids and autotrophic reference plants were used in order to elucidate the nutritional resources utilized by the orchids. Key Results Six out of the seven MH orchid species were mycorrhizal with either wood- or litter-decaying saprotrophic fungi. Only one orchid species was associated with ectomycorrhizal fungi. Stable isotope abundance patterns showed significant distinctions between orchids mycorrhizal with the three groups of fungal hosts. Conclusions Mycoheterotrophic orchids utilizing saprotrophic non-Rhizoctonia fungi as a carbon and nutrient source are clearly more frequent than hitherto assumed. On the basis of this kind of nutrition, orchids can thrive in deeply shaded, light-limiting forest understoreys even without support from ectomycorrhizal fungi. Sub-tropical East Asia appears to be a hotspot for orchids mycorrhizal with saprotrophic non-Rhizoctonia fungi. PMID:26113634

  18. Congenital cataract, facial dysmorphism and demyelinating neuropathy (CCFDN) in 10 Czech gypsy children – frequent and underestimated cause of disability among Czech gypsies

    PubMed Central

    2014-01-01

    Background Congenital Cataract Facial Dysmorphism and demyelinating Neuropathy (CCFDN, OMIM 604468) is an autosomal recessive multi-system disorder which was first described in Bulgarian Gypsies in 1999. It is caused by the homozygous founder mutation c.863 + 389C > T in the CTDP1 gene. The syndrome has been described exclusively in patients of Gypsy ancestry. The prevalence of this disorder in the Gypsy population in the Czech Republic and Central Europe is not known and is probably underestimated and under-diagnosed. Methods We clinically diagnosed and assessed 10 CCFDN children living in the Czech Republic. All patients are children of different ages, all of Gypsy origin born in the Czech Republic. Molecular genetic testing for the founder CTDP1 gene mutation was performed. Results All patients are homozygous for the c.863 + 389C > T mutation in the CTDP1 gene. All patients presented a bilateral congenital cataract and microphthalmos and had early cataract surgery. Correct diagnosis was not made until the age of two. All patients had variably delayed motor milestones. Gait is characteristically paleocerebellar in all the patients. Mental retardation was variable and usually mild. Conclusions Clinical diagnosis of CCFDN should be easy for an informed pediatrician or neurologist by the obligate signalling trias of congenital bilateral cataract, developmental delay and later demyelinating neuropathy. Our data indicate a probably high prevalence of CCFDN in the Czech Gypsy ethnic subpopulation. PMID:24690360

  19. National survey data for zoonotic schistosomiasis in the Philippines grossly underestimates the true burden of disease within endemic zones: implications for future control.

    PubMed

    Olveda, Remigio M; Tallo, Veronica; Olveda, David U; Inobaya, Marianette T; Chau, Thao N; Ross, Allen G

    2016-04-01

    Zoonotic schistosomiasis has a long endemic history in the Philippines. Human mass drug administration has been the cornerstone of schistosomiasis control in the country for the past three decades. Recent publications utilizing retrospective national survey data have indicated that the national human prevalence of the disease is <1%, hence the disease is now close to elimination. However, the evidence for such a claim is weak, given that less than a third of the human population is currently being treated annually within endemic zones and only a third of those treated actually swallow the tablets. For those who consume the drug at the single oral dose of 40mg/kg, the estimated cure rate is 52% based on a recent meta-analysis. Thus, approximately 5% of the endemic human population is in reality receiving the appropriate treatment. To compound this public health problem, most of the bovines in the endemic communities are concurrently infected but are not treated under the current national control programme. Given this evidence, it is believed that the human prevalence of schistosomiasis within endemic regions has been grossly underestimated. Inherent flaws in the reporting of national schistosomiasis prevalence data are reported here, and the problems of utilizing national retrospective data in making geographic information system (GIS) risk maps and advising policy makers of the outcomes are highlighted. PMID:26820760

  20. Dynamic Evolutionary Changes in Blood Flow Measured by MDCT in a Hepatic VX2 Tumor Implant over an Extended 28-day Growth Period: Time-Density Curve Analysis1

    PubMed Central

    Wu, Hanping; Exner, Agata A.; Shi, Hong; Bear, Joshua; Haaga, John R.

    2012-01-01

    Rationale and Objectives The enhancement pattern of malignant tumors has been studied in short-term animal models (7–14 days), but the reported results have been variable and inconsistent. The purpose of this study was to investigate the changing blood flow characteristics of VX2 tumors implanted in rabbit livers with contrast-enhanced multidetector computed tomography (MDCT) to establish a predictable pattern of vascular evolution over an extended 28-day growth period. Materials and Methods VX2 carcinoma was implanted in livers of 10 male New Zealand White rabbits. Dynamic CT (2/seconds × 60 seconds) was conducted on days 7, 14, 21, and 28 after tumor implantation. Enhancement parameters of time-density curve (TDC), time to start (T0), time to peak (TP), maximum enhancement (ΔH), slope of enhancement (SLe), and washout (SLw) in tumor center, tumor rim, and normal liver were analyzed. Tumor samples corresponding to CT images of one tumor on days 14 and 21 and seven tumors on day 28 were stained with hematoxylin and eosin and anti-CD31 monoclonal antibody. The relationship between enhancement parameters and histology parameters (thickness of tumor border, extent of blood stasis, and luminar vessel density) was analyzed. Results Consistent growth, appearance, and vascular changes occurred in 7 of 10 animals over the 4-week observation period. Peripheral rim-like enhancement was noted in CT images. TDC analysis showed that tumor rim enhancement was pronounced and more rapid than normal liver initially but this difference diminished with tumor progression. The SLe, SLw, and ΔH decreased from 10.03 ± 3.25 Hu/second, 0.42 ± 0.25 Hu/sec, and 58.00 ± 25.27 Hu on day 7 to 5.86 ± 2.73 Hu/second, 0.10 ± 0.13 Hu/second, and 37.78 ± 8.89 Hu/second on day 28, respectively. TP increased from 12.71 ± 4.85 seconds on day 7 to 25.57 ± 7.75 seconds on day 28. No significant changes were noted on the TDC parameters in normal liver. The maximum density difference between

  1. A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle

    PubMed Central

    Kok, Jasper F.

    2011-01-01

    Mineral dust aerosols impact Earth’s radiation budget through interactions with clouds, ecosystems, and radiation, which constitutes a substantial uncertainty in understanding past and predicting future climate changes. One of the causes of this large uncertainty is that the size distribution of emitted dust aerosols is poorly understood. The present study shows that regional and global circulation models (GCMs) overestimate the emitted fraction of clay aerosols (< 2 μm diameter) by a factor of ∼2–8 relative to measurements. This discrepancy is resolved by deriving a simple theoretical expression of the emitted dust size distribution that is in excellent agreement with measurements. This expression is based on the physics of the scale-invariant fragmentation of brittle materials, which is shown to be applicable to dust emission. Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity of emitted dust. On local and regional scales, this affects the magnitude and possibly the sign of the dust radiative forcing, with implications for numerical weather forecasting and regional climate predictions in dusty regions. On a global scale, the dust cycle in most GCMs is tuned to match radiative measurements, such that the overestimation of the radiative cooling of a given quantity of emitted dust has likely caused GCMs to underestimate the global dust emission rate. This implies that the deposition flux of dust and its fertilizing effects on ecosystems may be substantially larger than thought. PMID:21189304

  2. Is worst-case scenario streamflow drought underestimated in British Columbia? A multi-century perspective for the south coast, derived from tree-rings

    NASA Astrophysics Data System (ADS)

    Coulthard, Bethany; Smith, Dan J.; Meko, David M.

    2016-03-01

    Recent streamflow droughts in south coastal British Columbia have had major socioeconomic and ecological impacts. Increasing drought severity under projected climate change poses serious water management challenges, particularly in the small coastal watersheds that serve as primary water sources for most communities in the region. A 332-year dendrohydrological record of regionalized mean summer streamflow for four watersheds is analyzed to place recent drought magnitudes in a long-term perspective. We present a novel approach for optimizing tree-ring based reconstructions in small watersheds in temperate environments, combining winter snow depth and summer drought sensitive proxies as model predictors. The reconstruction model, estimated by regression of observed flows on Tsuga mertensiana ring-width variables and a tree-ring derived paleorecord of the Palmer Drought Severity Index, explains 64% of the regionalized streamflow variance. The model is particularly accurate at estimating lowest flow events, and provides the strongest annually resolved paleohydrological record in British Columbia. The extended record suggests that since 1658 sixteen natural droughts have occurred that were more extreme than any within the instrumental period. Flow-duration curves show more severe worst-case scenario droughts and a higher probability of those droughts in the long-term reconstruction than in the hydrometric data. Such curves also highlight the value of dendrohydrology for probabilistic drought assessment. Our results suggest current water management strategies based on worst-case scenarios from historical gauge data likely underestimate the potential magnitudes of natural droughts. If the low-flow magnitudes anticipated under climate change co-occur with lowest possible natural flows, streamflow drought severities in small watersheds in south coastal British Columbia could exceed any of those experienced in the past ∼350 years.

  3. Are We Under-Estimating the Association between Autism Symptoms?: The Importance of Considering Simultaneous Selection When Using Samples of Individuals Who Meet Diagnostic Criteria for an Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Murray, Aja Louise; McKenzie, Karen; Kuenssberg, Renate; O'Donnell, Michael

    2014-01-01

    The magnitude of symptom inter-correlations in diagnosed individuals has contributed to the evidence that autism spectrum disorders (ASD) is a fractionable disorder. Such correlations may substantially under-estimate the population correlations among symptoms due to simultaneous selection on the areas of deficit required for diagnosis. Using…

  4. On the order of general linear methods.

    SciTech Connect

    Constantinescu, E. M.; Mathematics and Computer Science

    2009-09-01

    General linear (GL) methods are numerical algorithms used to solve ODEs. The standard order conditions analysis involves the GL matrix itself and a starting procedure; however, a finishing method (F) is required to extract the actual ODE solution. The standard order analysis and stability are sufficient for the convergence of any GL method. Nonetheless, using a simple GL scheme, we show that the order definition may be too restrictive. Specifically, the order for GL methods with low order intermediate components may be underestimated. In this note we explore the order conditions for GL schemes and propose a new definition for characterizing the order of GL methods, which is focused on the final result--the outcome of F--and can provide more effective algebraic order conditions.

  5. 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

  6. The case for case studies in nursing research: the problem of generalization.

    PubMed

    Sharp, K

    1998-04-01

    This paper examines the logic of generalizing from case studies and other nonrepresentative samples. It is argued that the generalizability of such research is often underestimated, because of a fundamental confusion about two quite distinct logical bases upon which generalizations can be made: empirical and theoretical. It is suggested that once it is accepted that theoretical generalizations do not depend upon representativeness for their validity, the full value of case study, and other small-scale qualitative research to nursing and other health care disciplines, can be appreciated. PMID:9578209

  7. A verified spider bite and a review of the literature confirm Indian ornamental tree spiders (Poecilotheria species) as underestimated theraphosids of medical importance.

    PubMed

    Fuchs, Joan; von Dechend, Margot; Mordasini, Raffaella; Ceschi, Alessandro; Nentwig, Wolfgang

    2014-01-01

    Literature on bird spider or tarantula bites (Theraphosidae) is rare. This is astonishing as they are coveted pets and interaction with their keepers (feeding, cleaning the terrarium or taking them out to hold) might increase the possibility for bites. Yet, this seems to be a rare event and might be why most theraphosids are considered to be harmless, even though the urticating hairs of many American species can cause disagreeable allergic reactions. We are describing a case of a verified bite by an Indian ornamental tree spider (Poecilotheria regalis), where the patient developed severe, long lasting muscle cramps several hours after the bite. We present a comprehensive review of the literature on bites of these beautiful spiders and conclude that a delayed onset of severe muscle cramps, lasting for days, is characteristic for Poecilotheria bites. We discuss Poecilotheria species as an exception from the general assumption that theraphosid bites are harmless to humans. PMID:24215987

  8. Do we Underestimate the Importance of Leaf Size in Plant Economics? Disproportional Scaling of Support Costs Within the Spectrum of Leaf Physiognomy

    PubMed Central

    Niinemets, Ülo; Portsmuth, Angelika; Tena, David; Tobias, Mari; Matesanz, Silvia; Valladares, Fernando

    2007-01-01

    Background Broad scaling relationships between leaf size and function do not take into account that leaves of different size may contain different fractions of support in petiole and mid-rib. Methods The fractions of leaf biomass in petiole, mid-rib and lamina, and the differences in chemistry and structure among mid-ribs, petioles and laminas were investigated in 122 species of contrasting leaf size, life form and climatic distribution to determine the extent to which differences in support modify whole-lamina and whole-leaf structural and chemical characteristics, and the extent to which size-dependent support investments are affected by plant life form and site climate. Key Results For the entire data set, leaf fresh mass varied over five orders of magnitude. The percentage of dry mass in mid-rib increased strongly with lamina size, reaching more than 40 % in the largest laminas. The whole-leaf percentage of mid-rib and petiole increased with leaf size, and the overall support investment was more than 60 % in the largest leaves. Fractional support investments were generally larger in herbaceous than in woody species and tended to be lower in Mediterranean than in cool temperate and tropical plants. Mid-ribs and petioles had lower N and C percentages, and lower dry to fresh mass ratio, but greater density (mass per unit volume) than laminas. N percentage of lamina without mid-rib was up to 40 % higher in the largest leaves than the total-lamina (lamina and mid-rib) N percentage, and up to 60 % higher than whole-leaf N percentage, while lamina density calculated without mid-rib was up to 80 % less than that with the mid-rib. For all leaf compartments, N percentage was negatively associated with density and dry to fresh mass ratio, while C percentage was positively linked to these characteristics, reflecting the overall inverse scaling between structural and physiological characteristics. However, the correlations between N and C percentages and structural

  9. Generalized holomorphic structures

    NASA Astrophysics Data System (ADS)

    Wang, Yicao

    2014-12-01

    We define the notion of generalized holomorphic principal bundles and establish that their associated vector bundles of holomorphic representations are generalized holomorphic vector bundles defined by M. Gualtieri. Motivated by our definition, several examples of generalized holomorphic structures are constructed. A reduction theorem of generalized holomorphic structures is also included.

  10. General Aviation Propulsion

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Programs exploring and demonstrating new technologies in general aviation propulsion are considered. These programs are the quiet, clean, general aviation turbofan (QCGAT) program; the general aviation turbine engine (GATE) study program; the general aviation propeller technology program; and the advanced rotary, diesel, and reciprocating engine programs.

  11. Generalized Cartan Calculus in general dimension

    DOE PAGESBeta

    Wang, Yi -Nan

    2015-07-22

    We develop the generalized Cartan Calculus for the groups G = SL(2,R) × R+, SL(5,R) and SO(5,5). They are the underlying algebraic structures of d=9,7,6 exceptional field theory, respectively. These algebraic identities are needed for the "tensor hierarchy" structure in exceptional field theory. The validity of Poincar\\'e lemmas in this new differential geometry is also discussed. Lastly, we explore some possible extension of the generalized Cartan calculus beyond the exceptional series.

  12. Generalized Cartan Calculus in general dimension

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Nan

    2015-07-01

    We develop the generalized Cartan Calculus for the groups and SO(5 , 5). They are the underlying algebraic structures of d = 9 , 7 , 6 exceptional field theory, respectively. These algebraic identities are needed for the "tensor hierarchy" structure in exceptional field theory. The validity of Poincaré lemmas in this new differential geometry is also discussed. Finally we explore some possible extension of the generalized Cartan calculus beyond the exceptional series.

  13. General Medical Surveillance Program

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Background on the General Medical Surveillance Program at LeRC is presented. The purpose of the General Medical Surveillance Program at LeRC is outlined, and the specifics of the program are discussed.

  14. Generalized Cartan Calculus in general dimension

    SciTech Connect

    Wang, Yi -Nan

    2015-07-22

    We develop the generalized Cartan Calculus for the groups G = SL(2,R) × R+, SL(5,R) and SO(5,5). They are the underlying algebraic structures of d=9,7,6 exceptional field theory, respectively. These algebraic identities are needed for the "tensor hierarchy" structure in exceptional field theory. The validity of Poincar\\'e lemmas in this new differential geometry is also discussed. Lastly, we explore some possible extension of the generalized Cartan calculus beyond the exceptional series.

  15. The General Conference Mennonites.

    ERIC Educational Resources Information Center

    Ediger, Marlow

    General Conference Mennonites and Old Order Amish are compared and contrasted in the areas of physical appearance, religious beliefs, formal education, methods of farming, and home settings. General Conference Mennonites and Amish differ in physical appearance and especially in dress. The General Conference Mennonite men and women dress the same…

  16. Generalized quantum entropies

    NASA Astrophysics Data System (ADS)

    Santos, A. P.; Silva, R.; Alcaniz, J. S.; Anselmo, D. H. A. L.

    2011-08-01

    A deduction of generalized quantum entropies within the Tsallis and Kaniadakis frameworks is derived using a generalization of the ordinary multinomial coefficient. This generalization is based on the respective deformed multiplication and division. We show that the two above entropies are consistent with ones arbitrarily assumed at other contexts.

  17. General Music Today Yearbook

    ERIC Educational Resources Information Center

    Rowman & Littlefield Education, 2005

    2005-01-01

    The collected 2004-2005 issues of General Music Today, the online journal of MENC's Society for General Music includes articles, research, reviews and resources of interest to general music teachers of all levels. Topics covered include working with special-needs students; emphasizing early childhood environment to enhance musical growth;…

  18. Assessing General Education Outcomes

    ERIC Educational Resources Information Center

    Yin, Alexander C.; Volkwein, J. Fredericks

    2010-01-01

    In both purpose and practice, general education in American higher education has experienced several recurring debates and national revivals. In a world with constantly evolving technology, students need a strong general education to be flexible and adaptable to the changes of the world. General education is an important component and requirement…

  19. Forces in General Relativity

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2010-01-01

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…

  20. Reframing General Education

    ERIC Educational Resources Information Center

    Zai, Robert, III.

    2015-01-01

    From the colonial colleges to the present-day flagship universities, the undergraduate general education curriculum has dramatically shifted from a single, faculty-prescribed, general program to a diverse array of elective, student-choice-driven, specialized programs of general studies. This transformation has also encouraged, if not established,…

  1. Self-report may underestimate trauma intrusions.

    PubMed

    Takarangi, Melanie K T; Strange, Deryn; Lindsay, D Stephen

    2014-07-01

    Research examining maladaptive responses to trauma routinely relies on spontaneous self-report to index intrusive thoughts, which assumes people accurately recognize and report their intrusive thoughts. However, "mind-wandering" research reveals people are not always meta-aware of their thought content: they often fail to notice shifts in their attention. In two experiments, we exposed subjects to trauma films, then instructed them to report intrusive thoughts during an unrelated reading task. Intermittently, we asked whether they were thinking about the trauma. As expected, subjects often spontaneously reported intrusive thoughts. However, they were also "caught" engaging in unreported trauma-oriented thoughts. The presence and frequency of intermittent probes did not influence self-caught intrusions. Both self-caught and probe-caught intrusions were related to an existing tendency toward intrusive cognition, film-related distress, and thought suppression attempts. Our data suggest people may lack meta-awareness of trauma-related thoughts, which has implications for theory, research and treatment relating to trauma-related psychopathology. PMID:24993526

  2. [Somatization disorder - an overdiagnosed but underestimated illness].

    PubMed

    Karvonen, Juha T; Läksy, Kristian; Räsänen, Sami

    2016-01-01

    Physical symptoms often occur in the absence of physical illness. This is termed somatization when the symptoms are caused by psychic factors. When abundant symptoms affect the functional capacity and cause subjective harm and seeking healthcare services, a psychic disorder may be in question. Somatization may be associated with numerous psychic disorders. It may, however, also be a question of a somatoform disorder having a physical symptom picture. Somatization disorder is one of the somatoform disorders. Recognition of the disorder is often the problem in its treatment. Establishing a long-term treatment relationship actually forms the basis for therapy. PMID:26951025

  3. Urinary diversion metabolic complications - underestimated problem.

    PubMed

    Krajewski, Wojciech; Piszczek, Radosław; Krajewska, Magdalena; Dembowski, Janusz; Zdrojowy, Romuald

    2014-01-01

    Bladder cancer is one of the most frequent human cancers. In 2011 more than six thousand people in Poland developed BC and more than three thousand died because of it. Treatment of bladder cancer depends on its stage. In less advanced tumours (Ta, Tcis, T1) transurethral resection of bladder tumor with adjuvant immunotherapy is often therapeutic. In more advanced cases (≥ T2) radical cystectomy is needed. There are several surgical types of post-cystectomy urinary diversion divided into two fundamental types - enabling and not enabling urine continence. The most common procedures include ureterocutaneostomy, ileal or colon conduit, orthopic ileal bladder, heterotopic continent bladder replacement (pouch) and urinary diversion via the rectum. Depending on type of cystectomy, various metabolic complications occur, because the absorptive-secretory function of used bowel segment is intact. Complications include bowel dysfunction, malabsorption of various vitamins, acid-base imbalance, electrolyte imbalance, abnormalities in bone metabolism, formation of renal calculi, secondary malignancies and disturbances in function of kidneys or liver. Early diagnosed complications can be treated easier, recognised in advanced stages are often irreversible. In our paper we present review of different approaches to bladder cancer treatment and metabolic complications occurring after these procedures. PMID:25166450

  4. Gut: An underestimated target organ for Aluminum.

    PubMed

    Vignal, C; Desreumaux, P; Body-Malapel, M

    2016-06-01

    Since World War II, several factors such as an impressive industrial growth, an enhanced environmental bioavailability and intensified food consumption have contributed to a significant amplification of human exposure to aluminum. Aluminum is particularly present in food, beverages, some drugs and airbone dust. In our food, aluminum is superimposed via additives and cooking utensils. Therefore, the tolerable intake of aluminum is exceeded for a significant part of the world population, especially in children who are more vulnerable to toxic effects of pollutants than adults. Faced with this oral aluminum influx, intestinal tract is an essential barrier, especially as 38% of ingested aluminum accumulates at the intestinal mucosa. Although still poorly documented to date, the impact of oral exposure to aluminum in conditions relevant to real human exposure appears to be deleterious for gut homeostasis. Aluminum ingestion affects the regulation of the permeability, the microflora and the immune function of intestine. Nowadays, several arguments are consistent with an involvement of aluminum as an environmental risk factor for inflammatory bowel diseases. PMID:26970682

  5. We underestimate uncertainties in our predictions.

    SciTech Connect

    Pilch, Martin M.

    2010-04-01

    Prediction is defined in the American Heritage Dictionary as follows: 'To state, tell about, or make known in advance, especially on the basis of special knowledge.' What special knowledge do we demand of modeling and simulation to assert that we have a predictive capability for high consequence applications? The 'special knowledge' question can be answered in two dimensions: the process and rigor by which modeling and simulation is executed and assessment results for the specific application. Here we focus on the process and rigor dimension and address predictive capability in terms of six attributes: (1) geometric and representational fidelity, (2) physics and material model fidelity, (3) code verification, (4) solution verification, (5) validation, and (6) uncertainty quantification. This presentation will demonstrate through mini-tutorials, simple examples, and numerous case studies how each attribute creates opportunities for errors, biases, or uncertainties to enter into simulation results. The demonstrations will motivate a set of practices that minimize the risk in using modeling and simulation for high-consequence applications while defining important research directions. It is recognized that there are cultural, technical, infrastructure, and resource barriers that prevent analysts from performing all analyses at the highest levels of rigor. Consequently, the audience for this talk is (1) analysts, so they can know what is expected of them, (2) decision makers, so they can know what to expect from modeling and simulation, and (3) the R&D community, so they can address the technical and infrastructure issues that prevent analysts from executing analyses in a practical, timely, and quality manner.

  6. [Toxocariasis - an underestimated problem in paediatrics].

    PubMed

    Hozyasz, Kamil; Milanowski, Andrzej

    2002-01-01

    Aspects of Toxocara spp. epidemiology and paratenic infestation of children are described. Human toxocariasis is caused by infestation of zoonotic roundworms of dogs and cats. Soil sampling showes widespread contamination of the environment, particularly parks and playgrounds, with the eggs of Toxocara spp. Toxocara seroprevelance values in children vary between 3.5% in the West Poland and 19% in the South-East Poland. Children more frequently have clinical symptoms o the disease because of the closer contact with contaminated soil in sand-boxes and relatively frequent geophagia. A 3 years old girl with covert toxocariasis is described. As this case illustrates, this disease can be present without its classic visceral, ocular or neurological manifestations. On admission to the hospital the results of blood tests were as follows: white blood cells count, 43x10(3)/ mm3 (norm <13x10(3)) and hyperosinophilia, 81%. The girl was treated with albendazole 15 mg/kg for five days, after one year the treatment was repeated. The patient was followed with blood samples throughout a period of one and half year. During that time results of serological tests for Toxocara canis were strongly positive. The lowest blood count was 20.0x10(3)/mm3 and eosinophilia, 19%. Possible association between high eosinophilia in toxocariasis and development of allergic and cardiovascular diseases is discussed. PMID:12426460

  7. [Drugs: an underestimated cause of arterial hypertension].

    PubMed

    Serveaux, Marianne; Burnier, Michel; Pruijm, Menno

    2014-09-10

    In Switzerland, as in other Occidental countries, the prevalence of arterial hypertension (AHT) in the adult population is around 30-40%. Among the causes of secondary AHT, drug induced hypertension is sometimes omitted. Many molecules can induce AHT or worsen it due to an interaction with anti hypertensive drugs. Among these, NSAIDs and anti depressants, widely prescribed, should be used with caution, particularly in patients at risk, namely: those with preexisting AHT, the elderly, or patients suffering from kidney disease, diabetes, and/or heart failure. Increases in blood pressure have also been described with anti-vascular endothelial growth factor (VEGF) drugs, used in the treatment of (metastatic) cancer. A thorough anamnesis of drugs, including over the counter ones, should be performed in every hypertensive patient, and can avoid cumbersome and unnecessary investigations and therapy. PMID:25322625

  8. The underestimated biodiversity of tropical grassy biomes.

    PubMed

    Murphy, Brett P; Andersen, Alan N; Parr, Catherine L

    2016-09-19

    For decades, there has been enormous scientific interest in tropical savannahs and grasslands, fuelled by the recognition that they are a dynamic and potentially unstable biome, requiring periodic disturbance for their maintenance. However, that scientific interest has not translated into widespread appreciation of, and concern about threats to, their biodiversity. In terms of biodiversity, grassy biomes are considered poor cousins of the other dominant biome of the tropics-forests. Simple notions of grassy biomes being species-poor cannot be supported; for some key taxa, such as vascular plants, this may be valid, but for others it is not. Here, we use an analysis of existing data to demonstrate that high-rainfall tropical grassy biomes (TGBs) have vertebrate species richness comparable with that of forests, despite having lower plant diversity. The Neotropics stand out in terms of both overall vertebrate species richness and number of range-restricted vertebrate species in TGBs. Given high rates of land-cover conversion in Neotropical grassy biomes, they should be a high priority for conservation and greater inclusion in protected areas. Fire needs to be actively maintained in these systems, and in many cases re-introduced after decades of inappropriate fire exclusion. The relative intactness of TGBs in Africa and Australia make them the least vulnerable to biodiversity loss in the immediate future. We argue that, like forests, TGBs should be recognized as a critical-but increasingly threatened-store of global biodiversity.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'. PMID:27502382

  9. America's Seniors: Marketers Are Underestimating Their Power.

    ERIC Educational Resources Information Center

    Clayton, Catherine

    Society has stereotyped the elderly as those who are unable, dependent, institutionalized, and handicapped in various other ways. Stereotyping older people in this manner allows them to be cast aside in the market as well. The marketing community should concentrate more on this thriving aggregate, for they have disposable income--some for the…

  10. Triangulating speech sound generalization.

    PubMed

    Miccio, Adele W; Powell, Thomas W

    2010-01-01

    Generalization refers to the extension of learned behaviours to novel conditions, and it is one of the criteria by which the effectiveness and efficiency of a remediation programme may be judged. This article extracts principles of generalization from the treatment literature, and provides examples of how this information may be used to help guide treatment decisions. Included is a discussion of client, clinician, and treatment variables that may contribute to the generalization process. PMID:20345260

  11. General practice 'going places'.

    PubMed

    Hughes, C

    1992-05-01

    This paper, which was presented at the Annual General Meeting of the Royal Australian College of General Practitioners in September 1991, outlines possible roles for the general practitioner in the public health system. Four fundamental steps need to be taken: affirmative action by health boards to include GPs in all activities; representation of the RACGP on health boards; adequate remuneration; and part time employment of GPs in all health care delivery service units. PMID:1520131

  12. Generalized quasi variational inequalities

    SciTech Connect

    Noor, M.A.

    1996-12-31

    In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.

  13. Generalized Fibonacci photon sieves

    NASA Astrophysics Data System (ADS)

    Ke, Jie; Zhang, Junyong

    2015-08-01

    We propose a family of zone plates which are produced by the generalized Fibonacci sequences and their axial focusing properties are analyzed in detail. Compared with traditional Fresnel zone plates, the generalized Fibonacci zone plates present two axial foci with equal intensity. Besides, we propose an approach to adjust the axial locations of the two foci by means of different optical path difference, and further give the deterministic ratio of the two focal distances which attributes to their own generalized Fibonacci sequences. The generalized Fibonacci zone plates may allow for new applications in micro and nanophotonics.

  14. Discrimination and Generalization.

    ERIC Educational Resources Information Center

    Stokes, Trevor

    1992-01-01

    This response to Chandler et al. (EC 604 147) suggests that generalization of social competence training be viewed from both functional and topographical perspectives which have scientific and practice biases, respectively. The paper proposes a generalization-discrimination continuum along which behaviors may be placed for optimum utility. (DB)

  15. NASA and general aviation

    NASA Technical Reports Server (NTRS)

    Ethell, J. L.

    1986-01-01

    General aviation remains the single most misunderstood sector of aeronautics in the United States. A detailed look at how general aviation functions and how NASA helps keep it on the cutting edge of technology in airfoils, airframes, commuter travel, environmental concerns, engines, propellers, air traffic control, agricultural development, electronics, and safety is given.

  16. Accountability for General Education.

    ERIC Educational Resources Information Center

    Klein, A. Owen

    This discussion of the role of general education in community college programs in Ontario begins with an acknowledgement of the absence of a broadly accepted working definition of general education and an admonition to community colleges to accept the responsibility for providing students with a total education. Next, the paper proposes various…

  17. Assessment of General Education

    ERIC Educational Resources Information Center

    Furman, Tanya

    2013-01-01

    The assessment of general education is often approached through broad surveys or standardized instruments that fail to capture the learning goals most faculty members desire for this portion of the curriculum. The challenge in remedying this situation lies, first, in defining general education in meaningful ways that can be both articulated and…

  18. Reliability Generalization: "Lapsus Linguae"

    ERIC Educational Resources Information Center

    Smith, Julie M.

    2011-01-01

    This study examines the proposed Reliability Generalization (RG) method for studying reliability. RG employs the application of meta-analytic techniques similar to those used in validity generalization studies to examine reliability coefficients. This study explains why RG does not provide a proper research method for the study of reliability,…

  19. General aviation's meteorological requirements

    NASA Technical Reports Server (NTRS)

    Newton, D.

    1985-01-01

    Communication of weather theory and information about weather service products to pilots in an accurate and comprehensible manner is essential to flying safety in general. Probably no one needs weather knowledge more than the people who fly through it. The specific subject of this overview is General Aviation's Meteorological Requirements.

  20. Triangulating Speech Sound Generalization

    ERIC Educational Resources Information Center

    Miccio, Adele W.; Powell, Thomas W.

    2010-01-01

    Generalization refers to the extension of learned behaviours to novel conditions, and it is one of the criteria by which the effectiveness and efficiency of a remediation programme may be judged. This article extracts principles of generalization from the treatment literature, and provides examples of how this information may be used to help guide…

  1. General Education! Not Again?

    ERIC Educational Resources Information Center

    Marsee, Stuart

    After reviewing definitions of general education and statements regarding its importance found in the literature, this paper presents observations to be considered in updating or developing general education programs. It is observed that many disciplines have developed excessive departmentalization; that administrators tend to view general…

  2. Communication: General Semantics Perspectives.

    ERIC Educational Resources Information Center

    Thayer, Lee, Ed.

    This book contains the edited papers from the eleventh International Conference on General Semantics, titled "A Search for Relevance." The conference questioned, as a central theme, the relevance of general semantics in a world of wars and human misery. Reacting to a fundamental Korzybski-ian principle that man's view of reality is distorted by…

  3. General George C. Marshall

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This is a portrait of General George C. Marshall in Army uniform. The Marshall Space Flight Center, a NASA field installation, was established in Huntsville, Alabama, in 1960. The Center was named in honor of General George C. Marshall, the Army Chief of Staff during World War II, Secretary of State, and Nobel Prize Wirner for his world-renowned Marshall Plan.

  4. General cardinality genetic algorithms

    PubMed

    Koehler; Bhattacharyya; Vose

    1997-01-01

    A complete generalization of the Vose genetic algorithm model from the binary to higher cardinality case is provided. Boolean AND and EXCLUSIVE-OR operators are replaced by multiplication and addition over rings of integers. Walsh matrices are generalized with finite Fourier transforms for higher cardinality usage. Comparison of results to the binary case are provided. PMID:10021767

  5. General Machinists Course Outline.

    ERIC Educational Resources Information Center

    Wilcox, Chester; And Others

    This curriculum guide for a general machinists course is intended for use in a program combining vocational English as a second language (VESL) with bilingual vocational education. A description of the VESL program design appears first. The next section provides a format on developing lesson plans for teaching the technical and general vocational…

  6. Generalized Latent Trait Models.

    ERIC Educational Resources Information Center

    Moustaki, Irini; Knott, Martin

    2000-01-01

    Discusses a general model framework within which manifest variables with different distributions in the exponential family can be analyzed with a latent trait model. Presents a unified maximum likelihood method for estimating the parameters of the generalized latent trait model and discusses the scoring of individuals on the latent dimensions.…

  7. General relativity and cosmology

    NASA Astrophysics Data System (ADS)

    Bucher, Martin; Ni, Wei-Tou

    2015-10-01

    This year marks the 100th anniversary of Einstein’s 1915 landmark paper “Die Feldgleichungen der Gravitation” in which the field equations of general relativity were correctly formulated for the first time, thus rendering general relativity a complete theory. Over the subsequent hundred years, physicists and astronomers have struggled with uncovering the consequences and applications of these equations. This paper, which was written as an introduction to six chapters dealing with the connection between general relativity and cosmology that will appear in the two-volume book One Hundred Years of General Relativity: From Genesis and Empirical Foundations to Gravitational Waves, Cosmology and Quantum Gravity, endeavors to provide a historical overview of the connection between general relativity and cosmology, two areas whose development has been closely intertwined.

  8. Evaluation of clouds and radiative fluxes in the EC-Earth general circulation model

    NASA Astrophysics Data System (ADS)

    Lacagnina, Carlo; Selten, Frank

    2014-11-01

    Observations, mostly from the International Satellite Cloud Climatology (ISCCP), are used to assess clouds and radiative fluxes in the EC-Earth general circulation model, when forced by prescribed observed sea surface temperatures. An ISCCP instrument simulator is employed to consistently compare model outputs with satellite observations. The use of a satellite simulator is shown to be imperative for model evaluation. EC-Earth exhibits the largest cloud biases in the tropics. It generally underestimates the total cloud cover but overestimates the optically thick clouds, with the net result that clouds exert an overly strong cooling effect in the model. Every cloud type has its own source of bias. The magnitude of the cooling due to the shortwave cloud radiative effect () is underestimated for the stratiform low-clouds, because the model simulates too few of them. In contrast, is overestimated for trade wind cumulus clouds, because in the model these are too thick. The clouds in the deep convection regions also lead to overestimate the . These clouds are generally too thick and there are too few mid and high thin clouds. These biases are consistent with the positive precipitation bias and the overly strong mass flux for deep convective plumes. Potential sources for the various cloud biases in the model are discussed.

  9. Generalized Fibonacci photon sieves.

    PubMed

    Ke, Jie; Zhang, Junyong

    2015-08-20

    We successfully extend the standard Fibonacci zone plates with two on-axis foci to the generalized Fibonacci photon sieves (GFiPS) with multiple on-axis foci. We also propose the direct and inverse design methods based on the characteristic roots of the recursion relation of the generalized Fibonacci sequences. By switching the transparent and opaque zones, according to the generalized Fibonacci sequences, we not only realize adjustable multifocal distances but also fulfill the adjustable compression ratio of focal spots in different directions. PMID:26368763

  10. General Chemistry for Engineers.

    ERIC Educational Resources Information Center

    Kybett, B. D.

    1982-01-01

    Discusses the relationship between molecular structure, intermolecular forces, and tensile strengths of a polymer and suggests that this is a logical way to introduce polymers into a general chemistry course. (Author/JN)

  11. Tuberculosis: General Information

    MedlinePlus

    TB Elimination Tuberculosis: General Information What is TB? Tuberculosis (TB) is a disease caused by germs that are spread from person ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination CS227840_A What Does a Positive Test ...

  12. General Information about Melanoma

    MedlinePlus

    ... Screening Research Melanoma Treatment (PDQ®)–Patient Version General Information About Melanoma Go to Health Professional Version Key ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  13. Generalizing twisted gauge invariance

    SciTech Connect

    Duenas-Vidal, Alvaro; Vazquez-Mozo, Miguel A.

    2009-05-01

    We discuss the twisting of gauge symmetry in noncommutative gauge theories and show how this can be generalized to a whole continuous family of twisted gauge invariances. The physical relevance of these twisted invariances is discussed.

  14. Generalized Anxiety Disorder

    MedlinePlus

    MENU Return to Web version Generalized Anxiety Disorder Overview What is anxiety? Anxiety is a word that describes feelings of worry, nervousness, fear, apprehension, concern or restlessness. Normal feelings ...

  15. Generalized higher gauge theory

    NASA Astrophysics Data System (ADS)

    Ritter, Patricia; Sämann, Christian; Schmidt, Lennart

    2016-04-01

    We study a generalization of higher gauge theory which makes use of generalized geometry and seems to be closely related to double field theory. The local kinematical data of this theory is captured by morphisms of graded manifolds between the canonical exact Courant Lie 2-algebroid T M ⊕ T ∗ M over some manifold M and a semistrict gauge Lie 2-algebra. We discuss generalized curvatures and infinitesimal gauge transformations. Finite gauge transformation as well as global kinematical data are then obtained from principal 2-bundles over 2-spaces. As dynamical principle, we consider first the canonical Chern-Simons action for such a gauge theory. We then show that a previously proposed 3-Lie algebra model for the six-dimensional (2,0) theory is very naturally interpreted as a generalized higher gauge theory.

  16. General Relativity and Energy

    ERIC Educational Resources Information Center

    Jackson, A. T.

    1973-01-01

    Reviews theoretical and experimental fundamentals of Einstein's theory of general relativity. Indicates that recent development of the theory of the continually expanding universe may lead to revision of the space-time continuum of the finite and unbounded universe. (CC)

  17. Science in General Education

    ERIC Educational Resources Information Center

    Read, Andrew F.

    2013-01-01

    General education must develop in students an appreciation of the power of science, how it works, why it is an effective knowledge generation tool, and what it can deliver. Knowing what science has discovered is desirable but less important.

  18. Generalized eruptive syringomas.

    PubMed

    Jamalipour, Mahnaz; Heidarpour, Mitra; Rajabi, Parvin

    2009-01-01

    Generalized eruptive syringoma is a rare clinical presentation of a benign adnexal tumor that derives from the intraepidermal portion of the eccrine sweat ducts. It presents as successive crops of small flesh-colored papules on the anterior body surfaces. It generally occurs in the peripubertal period. Treatment of this benign condition is cosmetic only. A case of a 28-year-old female with an eight-year history of eruptive syringoma is presented. PMID:20049275

  19. Symmetric generalized binomial distributions

    SciTech Connect

    Bergeron, H.; Curado, E. M. F.; Gazeau, J. P.; Rodrigues, Ligia M. C. S. E-mail: evaldo@cbpf.br E-mail: ligia@cbpf.br

    2013-12-15

    In two recent articles, we have examined a generalization of the binomial distribution associated with a sequence of positive numbers, involving asymmetric expressions of probabilities that break the symmetry win-loss. We present in this article another generalization (always associated with a sequence of positive numbers) that preserves the symmetry win-loss. This approach is also based on generating functions and presents constraints of non-negativeness, similar to those encountered in our previous articles.

  20. Matter in general relativity

    NASA Technical Reports Server (NTRS)

    Ray, J. R.

    1982-01-01

    Two theories of matter in general relativity, the fluid theory and the kinetic theory, were studied. Results include: (1) a discussion of various methods of completing the fluid equations; (2) a method of constructing charged general relativistic solutions in kinetic theory; and (3) a proof and discussion of the incompatibility of perfect fluid solutions in anisotropic cosmologies. Interpretations of NASA gravitational experiments using the above mentioned results were started. Two papers were prepared for publications based on this work.

  1. General aviation and community development

    NASA Technical Reports Server (NTRS)

    Sincoff, M. Z. (Editor); Dajani, J. S. (Editor)

    1975-01-01

    The summer program is summarized. The reports presented concern (1) general aviation components, (2) general aviation environment, (3) community perspective, and (4) transportation and general aviation in Virginia.

  2. Limitations of clinical trials in chronic diseases: is the efficacy of methotrexate (MTX) underestimated in polyarticular psoriatic arthritis on the basis of limitations of clinical trials more than on limitations of MTX, as was seen in rheumatoid arthritis?

    PubMed

    Pincus, Theodore; Bergman, Martin J; Yazici, Yusuf

    2015-01-01

    Clinical trials are the optimal method to establish efficacy of a drug versus placebo or another drug. Nonetheless, important limitations are seen, particularly in chronic diseases over long periods, although most are ignored. Pragmatic limitations of clinical trials include a relatively short observation period, suboptimal dosage schedules, suboptimal surrogate markers for long-term outcomes, statistically significant results which may not be clinically unimportant and vice versa. Even ideal clinical trials have intrinsic limitations, including the influence of design on results, data reported in groups which ignore individual variation, non-standard observer-dependent interpretation of a balance of efficacy and toxicity, and distortion of a "placebo effect." Limitations are seen in many clinical trials of methotrexate (MTX) in rheumatoid arthritis (RA) and psoriatic arthritis (PsA). The first MTX clinical trial in rheumatology documented excellent efficacy in PsA, but frequent adverse events in 1964, explained by intravenous doses up to 150 kg. MTX was abandoned until the 1980s for RA, while gold salts and penicillamine were termed "remission-inducing," on the basis limitations of clinical trials. In the most recent MTX in PsA (MIPA) trial, all outcomes favoured MTX, but only patient and physician global estimates met the p<0.05 criterion. A conclusion of "no evidence for MTX improving synovitis" appears explained by insufficient statistical power, wide individual variation, no subsets, low doses, and other limitations. MTX appears less efficacious in PsA than RA, but may be underestimated in PsA, similar to historical problems in RA, resulting more from limitations of clinical trials than from limitations of MTX. PMID:26472658

  3. Generalized galilean genesis

    SciTech Connect

    Nishi, Sakine; Kobayashi, Tsutomu

    2015-03-31

    The galilean genesis scenario is an alternative to inflation in which the universe starts expanding from Minkowski in the asymptotic past by violating the null energy condition stably. Several concrete models of galilean genesis have been constructed so far within the context of galileon-type scalar-field theories. We give a generic, unified description of the galilean genesis scenario in terms of the Horndeski theory, i.e., the most general scalar-tensor theory with second-order field equations. In doing so we generalize the previous models to have a new parameter (denoted by α) which results in controlling the evolution of the Hubble rate. The background dynamics is investigated to show that the generalized galilean genesis solution is an attractor, similarly to the original model. We also study the nature of primordial perturbations in the generalized galilean genesis scenario. In all the models described by our generalized genesis Lagrangian, amplification of tensor perturbations does not occur as opposed to what happens in quasi-de Sitter inflation. We show that the spectral index of curvature perturbations is determined solely from the parameter α and does not depend on the other details of the model. In contrast to the original model, a nearly scale-invariant spectrum of curvature perturbations is obtained for a specific choice of α.

  4. Generalized energy failure criterion

    PubMed Central

    Qu, R. T.; Zhang, Z. J.; Zhang, P.; Liu, Z. Q.; Zhang, Z. F.

    2016-01-01

    Discovering a generalized criterion that can predict the mechanical failure of various different structural materials is one of ultimate goals for scientists in both material and mechanics communities. Since the first study on the failure criterion of materials by Galileo, about three centuries have passed. Now we eventually find the “generalized energy criterion”, as presented here, which appears to be one universal law for various different kinds of materials. The validity of the energy criterion for quantitatively predicting the failure is experimentally confirmed using a metallic glass. The generalized energy criterion reveals the competition and interaction between shear and cleavage, the two fundamental inherent failure mechanisms, and thus provides new physical insights into the failure prediction of materials and structural components. PMID:26996781

  5. Generalized energy failure criterion.

    PubMed

    Qu, R T; Zhang, Z J; Zhang, P; Liu, Z Q; Zhang, Z F

    2016-01-01

    Discovering a generalized criterion that can predict the mechanical failure of various different structural materials is one of ultimate goals for scientists in both material and mechanics communities. Since the first study on the failure criterion of materials by Galileo, about three centuries have passed. Now we eventually find the "generalized energy criterion", as presented here, which appears to be one universal law for various different kinds of materials. The validity of the energy criterion for quantitatively predicting the failure is experimentally confirmed using a metallic glass. The generalized energy criterion reveals the competition and interaction between shear and cleavage, the two fundamental inherent failure mechanisms, and thus provides new physical insights into the failure prediction of materials and structural components. PMID:26996781

  6. Warped general gauge mediation

    NASA Astrophysics Data System (ADS)

    McGarrie, Moritz; Thompson, Daniel C.

    2010-12-01

    We develop the formalism of “general gauge mediation” for five-dimensional theories in a slice of AdS space. A set of current correlators encodes the effect of a supersymmetry breaking hidden sector localized on the IR brane. These current correlators provide a tree-level gaugino mass and loop-level sfermion masses on the UV brane. We also use this formalism to calculate the Casimir energy and masses for bulk hyperscalars. To illustrate this general construction we consider a perturbative hidden sector of generalized messengers coupled to a spurion. For models with large warping, we find that when the AdS warp factor k is less than the characteristic mass scale M of the hidden sector, the whole Kaluza-Klein tower of vector superfields propagate supersymmetry breaking effects to the UV brane. When M is less than k, the zero modes dominate.

  7. Generalized energy failure criterion

    NASA Astrophysics Data System (ADS)

    Qu, R. T.; Zhang, Z. J.; Zhang, P.; Liu, Z. Q.; Zhang, Z. F.

    2016-03-01

    Discovering a generalized criterion that can predict the mechanical failure of various different structural materials is one of ultimate goals for scientists in both material and mechanics communities. Since the first study on the failure criterion of materials by Galileo, about three centuries have passed. Now we eventually find the “generalized energy criterion”, as presented here, which appears to be one universal law for various different kinds of materials. The validity of the energy criterion for quantitatively predicting the failure is experimentally confirmed using a metallic glass. The generalized energy criterion reveals the competition and interaction between shear and cleavage, the two fundamental inherent failure mechanisms, and thus provides new physical insights into the failure prediction of materials and structural components.

  8. General Relativity Today

    NASA Astrophysics Data System (ADS)

    Blandford, Roger D.

    2016-01-01

    A hundred years after its birth, general relativity has become a highly successful theory in the sese that it has passed many experimental and observational tests and finds widespread application to diverse set of cosmic phenomena. It remains an accurate research field as more tests are deployed, epitomized by the exciting prospect of detecting gravitational radiation directly. General realtivity is the essential foundation of modern cosmology and underlies our detailed description of the black holes and neutron stars that are ultimately responsible for the most powerful and dramatic cosmic sources. The interface with physics on both the largest and the smallest scales continues to be very fertile. In this talk I will attempt to highlight some key steps along the way to general relativity today.

  9. Generalized Random Events

    NASA Astrophysics Data System (ADS)

    Skřivánek, Václav; Frič, Roman

    2015-12-01

    Phenomena in quantum physics motivate studies of mathematical quantum structures and generalized probability. We introduce a new domain of generalized probability which is equivalent to the difference posets (also to effect algebras) of fuzzy sets. It is in terms of a partial operation of addition and it has a natural interpretation as a disjunction in the original spirit of G. Boole. The extension to a binary operation leads to the Łukasiewicz operations, bold algebras and fuzzy probability. We study states on products and mention some applications.

  10. General aviation technology assessment

    NASA Technical Reports Server (NTRS)

    Jacobson, I. D.

    1975-01-01

    The existing problem areas in general aviation were investigated in order to identify those which can benefit from technological payoffs. The emphasis was placed on acceptance by the pilot/passenger in areas such as performance, safety, handling qualities, ride quality, etc. Inputs were obtained from three sectors: industry; government; and user, although slanted toward the user group. The results should only be considered preliminary due to the small sample sizes of the data. Trends are evident however and a general methodology for allocating effort in future programs is proposed.

  11. Generalized Communities in Networks.

    PubMed

    Newman, M E J; Peixoto, Tiago P

    2015-08-21

    A substantial volume of research is devoted to studies of community structure in networks, but communities are not the only possible form of large-scale network structure. Here, we describe a broad extension of community structure that encompasses traditional communities but includes a wide range of generalized structural patterns as well. We describe a principled method for detecting this generalized structure in empirical network data and demonstrate with real-world examples how it can be used to learn new things about the shape and meaning of networks. PMID:26340218

  12. Generalized compliant motion primitive

    NASA Technical Reports Server (NTRS)

    Backes, Paul G. (Inventor)

    1994-01-01

    This invention relates to a general primitive for controlling a telerobot with a set of input parameters. The primitive includes a trajectory generator; a teleoperation sensor; a joint limit generator; a force setpoint generator; a dither function generator, which produces telerobot motion inputs in a common coordinate frame for simultaneous combination in sensor summers. Virtual return spring motion input is provided by a restoration spring subsystem. The novel features of this invention include use of a single general motion primitive at a remote site to permit the shared and supervisory control of the robot manipulator to perform tasks via a remotely transferred input parameter set.

  13. Generalized Communities in Networks

    NASA Astrophysics Data System (ADS)

    Newman, M. E. J.; Peixoto, Tiago P.

    2015-08-01

    A substantial volume of research is devoted to studies of community structure in networks, but communities are not the only possible form of large-scale network structure. Here, we describe a broad extension of community structure that encompasses traditional communities but includes a wide range of generalized structural patterns as well. We describe a principled method for detecting this generalized structure in empirical network data and demonstrate with real-world examples how it can be used to learn new things about the shape and meaning of networks.

  14. General Environmental Verification Specification

    NASA Technical Reports Server (NTRS)

    Milne, J. Scott, Jr.; Kaufman, Daniel S.

    2003-01-01

    The NASA Goddard Space Flight Center s General Environmental Verification Specification (GEVS) for STS and ELV Payloads, Subsystems, and Components is currently being revised based on lessons learned from GSFC engineering and flight assurance. The GEVS has been used by Goddard flight projects for the past 17 years as a baseline from which to tailor their environmental test programs. A summary of the requirements and updates are presented along with the rationale behind the changes. The major test areas covered by the GEVS include mechanical, thermal, and EMC, as well as more general requirements for planning, tracking of the verification programs.

  15. Generalized Structured Component Analysis

    ERIC Educational Resources Information Center

    Hwang, Heungsun; Takane, Yoshio

    2004-01-01

    We propose an alternative method to partial least squares for path analysis with components, called generalized structured component analysis. The proposed method replaces factors by exact linear combinations of observed variables. It employs a well-defined least squares criterion to estimate model parameters. As a result, the proposed method…

  16. GENERAL PERMITS DATABASE

    EPA Science Inventory

    Resource Purpose:This database was used to provide permit writers with a library of examples for writing general permits. It has not been maintained and is outdated and will be removed. Water Permits Division is trying to determine whether or not to recreate this databas...

  17. Generalized Procrustes Analysis

    ERIC Educational Resources Information Center

    Gower, J. C.

    1975-01-01

    Concerned with another form of analysis of m sets of matrices, the Procrustes idea is generalized so that all m sets are simultaneously translated, rotated, reflected and scaled so that a goodness of fit criterion is optimised. A computational technique is given, results of which can be summarized in analysis of variance form. (RC)

  18. General Construction. Instructor Manual.

    ERIC Educational Resources Information Center

    Laborers-AGC Education and Training Fund, Pomfret Center, CT.

    This guide contains materials for a general construction course. Introductory materials include a list of videos, schedule for the 10-day course, and tools and material list. The course is divided into 10 sections. Each section consists of some or all of these components: list of trainee objectives, instructor notes, instructor outline,…

  19. General Aviation Manpower Study.

    ERIC Educational Resources Information Center

    Feller, Richard

    1982-01-01

    Highlights a study examining manpower supply/demand in general aviation. Eight job categories were examined: pilots, flight instructors, engineers, machinists/toolers, and A&P, airframe, and avionics technicians. Findings among others indicate that shortages in indicated job categories exist because personnel are recruited by other industries. (JN)

  20. General Achievement Trends: Maryland

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  1. General Achievement Trends: Arkansas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  2. General Achievement Trends: Idaho

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  3. General Achievement Trends: Nebraska

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  4. General Achievement Trends: Colorado

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  5. General Achievement Trends: Iowa

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  6. General Achievement Trends: Hawaii

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  7. General Achievement Trends: Kentucky

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  8. General Achievement Trends: Florida

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  9. General Achievement Trends: Texas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  10. General Achievement Trends: Oregon

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  11. General Achievement Trends: Virginia

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  12. 14 CFR 4 - General

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false General Section 4 Section Section 4 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Balance...

  13. 14 CFR 8 - General

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false General Section 8 Section Section 8 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Profit and...

  14. General Achievement Trends: Tennessee

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  15. Inspector General Spotlight.

    ERIC Educational Resources Information Center

    Office of Inspector General (ED), Washington, DC.

    This pamphlet summarizes the accomplishments of the United States Department of Education's Office of Inspector General (OIG) during the 6-month period ended March 31, 1990. The pamphlet focuses on audit, investigative, and other activities, in order to provide information about current OIG efforts to prevent and detect fraud, waste, or…

  16. General George C. Marshall

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The Marshall Space Flight Center, a NASA field installation, was established at Huntsville, Alabama, in 1960. The Center was named in honor of General George C. Marshall, the Army Chief of Staff during World War II, Secretary of State, and Nobel Prize Wirner for his world-renowned Marshall Plan.

  17. Chemistry as General Education

    ERIC Educational Resources Information Center

    Tro, Nivaldo J.

    2004-01-01

    The efficacy of different science and chemistry courses for science-major and non-major students, and the question of chemistry's contribution to general education are evaluated. Chemistry and science curriculum are too profession- and consumer-oriented, and to overcome this problem, it is advised that all disciplines must incorporate the major…

  18. IAHS General Assembly

    NASA Astrophysics Data System (ADS)

    Peters, Helen J.

    The International Association of Hydrological Sciences (IAHS) General Assembly, held as part of the International Union of Geodesy and Geophysics (IUGG) Assembly, August 9-22, 1987, in Vancouver, Canada, had an estimated 500 attendees. At least 20 countries were represented by official delegates. Attendance from the United States is estimated at 120, with Helen J. Peters (California Department of Water Resources, Sacramento) as chief delegate and Marshall E. Moss (U.S. Geological Survey (USGS), Reston, Va.) as alternate delegate and future chief delegate for the 1991 General Assembly.The Canadian Organizing Committee had done a masterful job of organizing the assembly, with excellent housing and meeting facilities on the University of British Columbia campus. In addition to five symposia and nine workshops, the IAHS Bureau and all commissions and the committees held several meetings. Some excellent social events and tours were included.

  19. Tests of General Relativity

    SciTech Connect

    Kramer, Michael

    2011-09-22

    The last years have seen continuing activities in the exploration of our understanding of gravity, motivated by results from precision cosmology and new precision astrophysical experiments. At the centre of attention lies the question as to whether general relativity is the correct theory of gravity. In answering this question, we work not only towards correctly interpreting the phenomenon of 'dark energy' but also towards the goal of achieving a quantum theory of gravity. In these efforts, the observations of pulsars, especially those in binary systems, play an important role. Pulsars do not only provide the only evidence for the existence of gravitational waves so far, but they also provide precision tests of general relativity and alternative theories of gravity. This talk summarizes the current state-of-art in these experiments and looks into the future.

  20. General stress response signaling

    PubMed Central

    Huo, Yi-Xin; Rosenthal, Adam Z.; Gralla, Jay D.

    2008-01-01

    E. coli responds to stress by a combination of specific and general transcription signaling pathways. The general pathways typically require the master stress regulator sigma38 (rpoS). Here we show that the signaling from multiple stresses that relax DNA is processed by a non-conserved 8 amino acid tail of the sigma 38 C-terminal domain (CTD). By contrast, responses to stresses that accumulate potassium glutamate do not rely on this short tail, but still require the overall CTD. In vitro transcription and footprinting studies suggest that multiple stresses can target a poised RNA polymerase and activate it by unwrapping DNA from a nucleosome-like state, allowing the RNA polymerase to escape into productive mode. This transition can be accomplished by either the DNA relaxation or potassium glutamate accumulation that characterizes many stresses. PMID:18761624

  1. Generalized constructive tree weights

    SciTech Connect

    Rivasseau, Vincent E-mail: adrian.tanasa@ens-lyon.org; Tanasa, Adrian E-mail: adrian.tanasa@ens-lyon.org

    2014-04-15

    The Loop Vertex Expansion (LVE) is a quantum field theory (QFT) method which explicitly computes the Borel sum of Feynman perturbation series. This LVE relies in a crucial way on symmetric tree weights which define a measure on the set of spanning trees of any connected graph. In this paper we generalize this method by defining new tree weights. They depend on the choice of a partition of a set of vertices of the graph, and when the partition is non-trivial, they are no longer symmetric under permutation of vertices. Nevertheless we prove they have the required positivity property to lead to a convergent LVE; in fact we formulate this positivity property precisely for the first time. Our generalized tree weights are inspired by the Brydges-Battle-Federbush work on cluster expansions and could be particularly suited to the computation of connected functions in QFT. Several concrete examples are explicitly given.

  2. General Education for Engineers

    NASA Astrophysics Data System (ADS)

    Takeda, Kunihiko

    The basic program of general education of engineers is based on European culture from the times of ancient Greece to the 20th century. However, when considering its results, such as colonialism and the World Wars, this system can be said to lack the most important goal of “culture,” which is “to accept the existence of others.” In particular, the cooperation of European culture and engineering has ravaged the weaker cultures and is currently causing severe environmental problems in nature. Therefore, when considering the general education of engineers, it is indispensable to doubt European scholarship and to analyze what is lacking in current Japanese educational programs. Then, it is desirable that the relationship between the mind and the body, the characteristics of the Japanese climate, and the essence of Japanese artisanship be taken into consideration. It may also be beneficial to study the Ainu culture for its qualities as a peaceful culture.

  3. Categorization = Decision Making + Generalization

    PubMed Central

    Seger, Carol A; Peterson, Erik J.

    2013-01-01

    We rarely, if ever, repeatedly encounter exactly the same situation. This makes generalization crucial for real world decision making. We argue that categorization, the study of generalizable representations, is a type of decision making, and that categorization learning research would benefit from approaches developed to study the neuroscience of decision making. Similarly, methods developed to examine generalization and learning within the field of categorization may enhance decision making research. We first discuss perceptual information processing and integration, with an emphasis on accumulator models. We then examine learning the value of different decision making choices via experience, emphasizing reinforcement learning modeling approaches. Next we discuss how value is combined with other factors in decision making, emphasizing the effects of uncertainty. Finally, we describe how a final decision is selected via thresholding processes implemented by the basal ganglia and related regions. We also consider how memory related functions in the hippocampus may be integrated with decision making mechanisms and contribute to categorization. PMID:23548891

  4. Generalized fiber Fourier optics.

    PubMed

    Cincotti, Gabriella

    2011-06-15

    A twofold generalization of the optical schemes that perform the discrete Fourier transform (DFT) is given: new passive planar architectures are presented where the 2 × 2 3 dB couplers are replaced by M × M hybrids, reducing the number of required connections and phase shifters. Furthermore, the planar implementation of the discrete fractional Fourier transform (DFrFT) is also described, with a waveguide grating router (WGR) configuration and a properly modified slab coupler. PMID:21686007

  5. Entrepreneurship within General Aviation

    NASA Technical Reports Server (NTRS)

    Ullmann, Brian M.

    1995-01-01

    Many modern economic theories place great importance upon entrepreneurship in the economy. Some see the entrepreneur as the individual who bears risk of operating a business in the face of uncertainty about future conditions and who is rewarded through profits and losses. The 20th century economist Joseph Schumpter saw the entrepreneur as the medium by which advancing technology is incorporated into society as businesses seek competitive advantages through more efficient product development processes. Due to the importance that capitalistic systems place upon entrepreneurship, it has become a well studied subject with many texts to discuss how entrepreneurs can succeed in modern society. Many entrepreneuring and business management courses go so far as to discuss the characteristic phases and prominent challenges that fledgling companies face in their efforts to bring a new product into a competitive market. However, even with all of these aids, start-up companies fail at an enormous rate. Indeed, the odds of shepherding a new company through the travails of becoming a well established company (as measured by the ability to reach Initial Public Offering (IPO)) have been estimated to be six in 1,000,000. Each niche industry has characteristic challenges which act as barriers to entry for new products into that industry. Thus, the applicability of broad generalizations is subject to limitations within niche markets. This paper will discuss entrepreneurship as it relates to general aviation. The goals of this paper will be to: introduce general aviation; discuss the details of marrying entrepreneurship with general aviation; and present a sample business plan which would characterize a possible entrepreneurial venture.

  6. The generalized quaternion sequence

    NASA Astrophysics Data System (ADS)

    Deveci, Ömür

    2016-04-01

    In this work, we define the recurrence sequence by using the relation matrix of the generalized quaternion group and then, we obtain miscellaneous properties of this sequence. Also, we obtain the cyclic groups and the semigroups which are produced by generating matrix of the sequence defined when read modulo m. Furthermore, we study this sequence modulo m, and then we derive the relationship among the order the cyclic groups obtained and the periods of the sequence defined.

  7. Turbulent General Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Eyink, G. L.

    2015-07-01

    Plasma flows with a magnetohydrodynamic (MHD)-like turbulent inertial range, such as the solar wind, require a generalization of general magnetic reconnection (GMR) theory. We introduce the slip velocity source vector per unit arclength of field line, the ratio of the curl of the non-ideal electric field in the generalized Ohm’s Law and magnetic field strength. It diverges at magnetic nulls, unifying GMR with null-point reconnection. Only under restrictive assumptions is the slip velocity related to the gradient of quasi-potential (which is the integral of parallel electric field along magnetic field lines). In a turbulent inertial range, the non-ideal field becomes tiny while its curl is large, so that line slippage occurs even while ideal MHD becomes accurate. The resolution is that ideal MHD is valid for a turbulent inertial range only in a weak sense that does not imply magnetic line freezing. The notion of weak solution is explained in terms of renormalization group (RG) type theory. The weak validity of the ideal Ohm’s law in the inertial range is shown via rigorous estimates of the terms in the generalized Ohm’s Law. All non-ideal terms are irrelevant in the RG sense and large-scale reconnection is thus governed solely by ideal dynamics. We discuss the implications for heliospheric reconnection, in particular for deviations from the Parker spiral model. Solar wind observations show that reconnection in a turbulence-broadened heliospheric current sheet, which is consistent with Lazarian-Vishniac theory, leads to slip velocities that cause field lines to lag relative to the spiral model.

  8. Alopecia in general medicine.

    PubMed

    Nalluri, Rajani; Harries, Matthew

    2016-02-01

    Appreciation of different types of hair loss (alopecia) that may be encountered in hospital medicine is important to ensure accurate diagnosis and management, identify underlying medical conditions or treatments that may present with increased hair loss, recognise autoimmune alopecias and their associations, and understand the significant psychological impact of hair loss on an individual. This article discusses common causes of hair loss, as well as those conditions that may be associated with systemic disease, relevant to a general physician. PMID:26833522

  9. On generalized logarithmic electrodynamics

    NASA Astrophysics Data System (ADS)

    Kruglov, S. I.

    2015-02-01

    The generalized logarithmic electrodynamics with two parameters and is considered. The indexes of refraction of light in the external magnetic field are calculated. In the case we come to results obtained by Gaete and Helayël-Neto (Eur Phys J C 74:2816, 2014). The bound on the values of , was obtained from the Biréfringence Magnétique du Vide (BMV) experiment. The symmetrical Belinfante energy-momentum tensor and dilatation current are found.

  10. Content of general practice.

    PubMed

    Lim, T O

    1991-06-01

    Eight general practitioners participated in a survey of content of general practice. This is useful as an indicator or morbidity in the community as well as of workload of general practice. A total of 3164 consultations were recorded, of which 2764 (87%) were because of an illness and the rest (13%) for other reasons like medical examinations, antenatal check, family planning advice, pregnancy tests, pap smear and vaccination. The old and the young have high consultation rates for an illness, men consulted as often as women. The most common illness seen was upper respiratory tract infections, accounting for 37% of all illnesses. Other common minor illnesses were skin infections (6%), genito-urinary infections (5%), minor musculoskeletal (6%) and gastrointestinal (6%) complaints as well as minor injuries and cuts (4%). Major disorders form an unusually low proportion (18%) of all illnesses seen, in comparison with figures from United Kingdom. The common major disorders seen were hypertension, asthma, chronic rheumatic disorders and diabetes. Circulatory disorders were remarkably rare, accounting for only 1% of illnesses. Psychological disorders, both major and minor, were also rarely seen, accounting for only 1% of illnesses which is in marked contrast with figures from the United Kingdom. Factors contributing to these notable findings are discussed. PMID:1839420

  11. Beyond generalized Proca theories

    NASA Astrophysics Data System (ADS)

    Heisenberg, Lavinia; Kase, Ryotaro; Tsujikawa, Shinji

    2016-09-01

    We consider higher-order derivative interactions beyond second-order generalized Proca theories that propagate only the three desired polarizations of a massive vector field besides the two tensor polarizations from gravity. These new interactions follow the similar construction criteria to those arising in the extension of scalar-tensor Horndeski theories to Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories. On the isotropic cosmological background, we show the existence of a constraint with a vanishing Hamiltonian that removes the would-be Ostrogradski ghost. We study the behavior of linear perturbations on top of the isotropic cosmological background in the presence of a matter perfect fluid and find the same number of propagating degrees of freedom as in generalized Proca theories (two tensor polarizations, two transverse vector modes, and two scalar modes). Moreover, we obtain the conditions for the avoidance of ghosts and Laplacian instabilities of tensor, vector, and scalar perturbations. We observe key differences in the scalar sound speed, which is mixed with the matter sound speed outside the domain of generalized Proca theories.

  12. Generalized Causal Mediation Analysis

    PubMed Central

    Albert, Jeffrey M.; Nelson, Suchitra

    2010-01-01

    Summary The goal of mediation analysis is to assess direct and indirect effects of a treatment or exposure on an outcome. More generally, we may be interested in the context of a causal model as characterized by a directed acyclic graph (DAG), where mediation via a specific path from exposure to outcome may involve an arbitrary number of links (or ‘stages’). Methods for estimating mediation (or pathway) effects are available for a continuous outcome and a continuous mediator related via a linear model, while for a categorical outcome or categorical mediator, methods are usually limited to two-stage mediation. We present a method applicable to multiple stages of mediation and mixed variable types using generalized linear models. We define pathway effects using a potential outcomes framework and present a general formula that provides the effect of exposure through any specified pathway. Some pathway effects are nonidentifiable and their estimation requires an assumption regarding the correlation between counterfactuals. We provide a sensitivity analysis to assess of the impact of this assumption. Confidence intervals for pathway effect estimates are obtained via a bootstrap method. The method is applied to a cohort study of dental caries in very low birth weight adolescents. A simulation study demonstrates low bias of pathway effect estimators and close-to-nominal coverage rates of confidence intervals. We also find low sensitivity to the counterfactual correlation in most scenarios. PMID:21306353

  13. General Relativity and Gravitation

    NASA Astrophysics Data System (ADS)

    Ashtekar, Abhay; Berger, Beverly; Isenberg, James; MacCallum, Malcolm

    2015-07-01

    Part I. Einstein's Triumph: 1. 100 years of general relativity George F. R. Ellis; 2. Was Einstein right? Clifford M. Will; 3. Cosmology David Wands, Misao Sasaki, Eiichiro Komatsu, Roy Maartens and Malcolm A. H. MacCallum; 4. Relativistic astrophysics Peter Schneider, Ramesh Narayan, Jeffrey E. McClintock, Peter Mészáros and Martin J. Rees; Part II. New Window on the Universe: 5. Receiving gravitational waves Beverly K. Berger, Karsten Danzmann, Gabriela Gonzalez, Andrea Lommen, Guido Mueller, Albrecht Rüdiger and William Joseph Weber; 6. Sources of gravitational waves. Theory and observations Alessandra Buonanno and B. S. Sathyaprakash; Part III. Gravity is Geometry, After All: 7. Probing strong field gravity through numerical simulations Frans Pretorius, Matthew W. Choptuik and Luis Lehner; 8. The initial value problem of general relativity and its implications Gregory J. Galloway, Pengzi Miao and Richard Schoen; 9. Global behavior of solutions to Einstein's equations Stefanos Aretakis, James Isenberg, Vincent Moncrief and Igor Rodnianski; Part IV. Beyond Einstein: 10. Quantum fields in curved space-times Stefan Hollands and Robert M. Wald; 11. From general relativity to quantum gravity Abhay Ashtekar, Martin Reuter and Carlo Rovelli; 12. Quantum gravity via unification Henriette Elvang and Gary T. Horowitz.

  14. Generalized Maximum Entropy

    NASA Technical Reports Server (NTRS)

    Cheeseman, Peter; Stutz, John

    2005-01-01

    A long standing mystery in using Maximum Entropy (MaxEnt) is how to deal with constraints whose values are uncertain. This situation arises when constraint values are estimated from data, because of finite sample sizes. One approach to this problem, advocated by E.T. Jaynes [1], is to ignore this uncertainty, and treat the empirically observed values as exact. We refer to this as the classic MaxEnt approach. Classic MaxEnt gives point probabilities (subject to the given constraints), rather than probability densities. We develop an alternative approach that assumes that the uncertain constraint values are represented by a probability density {e.g: a Gaussian), and this uncertainty yields a MaxEnt posterior probability density. That is, the classic MaxEnt point probabilities are regarded as a multidimensional function of the given constraint values, and uncertainty on these values is transmitted through the MaxEnt function to give uncertainty over the MaXEnt probabilities. We illustrate this approach by explicitly calculating the generalized MaxEnt density for a simple but common case, then show how this can be extended numerically to the general case. This paper expands the generalized MaxEnt concept introduced in a previous paper [3].

  15. Awareness under general anesthesia.

    PubMed

    Sigalovsky, Natalie

    2003-10-01

    General anesthesia aims to eliminate patients' awareness of excruciating pain during surgery. Nevertheless, rare occurrences of patient awareness continue because the problem is not yet completely preventable. One study puts the incidence of awareness at 0.18% for patients receiving muscle relaxants and at 0.10% for patients not given relaxant drugs. Awareness experiences frighten patients and impact their implicit and explicit memories in ways that can leave a lifetime of residual emotional and psychological problems ranging from sleep disturbances, nightmares, and daytime anxiety that may subside with time to development of post-traumatic stress disorder. Most anesthetists monitor depth of anesthesia by assessing intraoperative hemodynamic responses to surgical stimuli--an approach questioned by some authors. Several depth-of-anesthesia monitors are available, but there is no ideal monitor that is 100% reliable. This review provides an overview of literature that reports findings associated with the monitoring and occurrence of intraoperative awareness. These studies indicate assessment methods that can be trusted when we provide general anesthesia and what measures can be taken to prevent recall by patients under general anesthesia. PMID:14625975

  16. General aviation in China

    NASA Astrophysics Data System (ADS)

    Hu, Xiaosi

    In the last four decades, China has accomplished economic reform successfully and grown to be a leading country in the world. As the "world factory", the country is able to manufacture a variety of industrial products from clothes and shoes to rockets and satellites. But the aviation industry has always been a weak spot and even the military relies on imported turbofan engines and jet fighters, not to mention the airlines. Recently China has launched programs such as ARJ21 and C919, and started reform to change the undeveloped situation of its aviation industry. As the foundation of the aviation industry, the development of general aviation is essential for the rise of commercial aviation. The primary goal of this study is to examine the general aviation industry and finds the issues that constrain the development of the industry in the system. The research method used in this thesis is the narrative research of qualitative approach since the policy instead of statistical data is analyzed. It appears that the main constraint for the general aviation industry is the government interference.

  17. Hyperuniformity and its generalizations.

    PubMed

    Torquato, Salvatore

    2016-08-01

    Disordered many-particle hyperuniform systems are exotic amorphous states of matter that lie between crystal and liquid: They are like perfect crystals in the way they suppress large-scale density fluctuations and yet are like liquids or glasses in that they are statistically isotropic with no Bragg peaks. These exotic states of matter play a vital role in a number of problems across the physical, mathematical as well as biological sciences and, because they are endowed with novel physical properties, have technological importance. Given the fundamental as well as practical importance of disordered hyperuniform systems elucidated thus far, it is natural to explore the generalizations of the hyperuniformity notion and its consequences. In this paper, we substantially broaden the hyperuniformity concept along four different directions. This includes generalizations to treat fluctuations in the interfacial area (one of the Minkowski functionals) in heterogeneous media and surface-area driven evolving microstructures, random scalar fields, divergence-free random vector fields, and statistically anisotropic many-particle systems and two-phase media. In all cases, the relevant mathematical underpinnings are formulated and illustrative calculations are provided. Interfacial-area fluctuations play a major role in characterizing the microstructure of two-phase systems (e.g., fluid-saturated porous media), physical properties that intimately depend on the geometry of the interface, and evolving two-phase microstructures that depend on interfacial energies (e.g., spinodal decomposition). In the instances of random vector fields and statistically anisotropic structures, we show that the standard definition of hyperuniformity must be generalized such that it accounts for the dependence of the relevant spectral functions on the direction in which the origin in Fourier space is approached (nonanalyticities at the origin). Using this analysis, we place some well-known energy

  18. Hyperuniformity and its generalizations

    NASA Astrophysics Data System (ADS)

    Torquato, Salvatore

    2016-08-01

    Disordered many-particle hyperuniform systems are exotic amorphous states of matter that lie between crystal and liquid: They are like perfect crystals in the way they suppress large-scale density fluctuations and yet are like liquids or glasses in that they are statistically isotropic with no Bragg peaks. These exotic states of matter play a vital role in a number of problems across the physical, mathematical as well as biological sciences and, because they are endowed with novel physical properties, have technological importance. Given the fundamental as well as practical importance of disordered hyperuniform systems elucidated thus far, it is natural to explore the generalizations of the hyperuniformity notion and its consequences. In this paper, we substantially broaden the hyperuniformity concept along four different directions. This includes generalizations to treat fluctuations in the interfacial area (one of the Minkowski functionals) in heterogeneous media and surface-area driven evolving microstructures, random scalar fields, divergence-free random vector fields, and statistically anisotropic many-particle systems and two-phase media. In all cases, the relevant mathematical underpinnings are formulated and illustrative calculations are provided. Interfacial-area fluctuations play a major role in characterizing the microstructure of two-phase systems (e.g., fluid-saturated porous media), physical properties that intimately depend on the geometry of the interface, and evolving two-phase microstructures that depend on interfacial energies (e.g., spinodal decomposition). In the instances of random vector fields and statistically anisotropic structures, we show that the standard definition of hyperuniformity must be generalized such that it accounts for the dependence of the relevant spectral functions on the direction in which the origin in Fourier space is approached (nonanalyticities at the origin). Using this analysis, we place some well-known energy

  19. Tachyons in general relativity

    SciTech Connect

    Schwartz, Charles

    2011-05-15

    We consider the motion of tachyons (faster-than-light particles) in the framework of general relativity. An important feature is the large contribution of low energy tachyons to the energy-momentum tensor. We also calculate the gravitational field produced by tachyons in particular geometric arrangements; and it appears that there could be self-cohering bundles of such matter. This leads us to suggest that such theoretical ideas might be relevant to major problems (dark matter and dark energy) in current cosmological models.

  20. Itch Management: General Principles.

    PubMed

    Misery, Laurent

    2016-01-01

    Like pain, itch is a challenging condition that needs to be managed. Within this setting, the first principle of itch management is to get an appropriate diagnosis to perform an etiology-oriented therapy. In several cases it is not possible to treat the cause, the etiology is undetermined, there are several causes, or the etiological treatment is not effective enough to alleviate itch completely. This is also why there is need for symptomatic treatment. In all patients, psychological support and associated pragmatic measures might be helpful. General principles and guidelines are required, yet patient-centered individual care remains fundamental. PMID:27578069

  1. Generalized qudit Choi maps

    SciTech Connect

    Jafarizadeh, M. A.; Rezaee, M.; Ahadpour, S.

    2006-10-15

    Following the linear programming prescription of Jafarizadeh et al. [Phys. Rev. A 72, 062106 (2005)], the d(multiply-in-circle sign)d Bell diagonal entanglement witnesses are provided. By using Jamiolkowski isomorphism, it is shown that the corresponding positive maps are the generalized qudit Choi maps. Also by manipulating particular d(multiply-in-circle sign)d Bell diagonal separable states and constructing corresponding bound entangled states, it is shown that the obtained d(multiply-in-circle sign)d Bell states diagonal entanglement witnesses (consequently qudit Choi maps) are nondecomposable in a certain range of their parameters.

  2. On generalized Volterra systems

    NASA Astrophysics Data System (ADS)

    Charalambides, S. A.; Damianou, P. A.; Evripidou, C. A.

    2015-01-01

    We construct a large family of evidently integrable Hamiltonian systems which are generalizations of the KM system. The algorithm uses the root system of a complex simple Lie algebra. The Hamiltonian vector field is homogeneous cubic but in a number of cases a simple change of variables transforms such a system to a quadratic Lotka-Volterra system. We present in detail all such systems in the cases of A3, A4 and we also give some examples from higher dimensions. We classify all possible Lotka-Volterra systems that arise via this algorithm in the An case.

  3. Nonlocal General Relativity

    NASA Astrophysics Data System (ADS)

    Mashhoon, Bahram

    2014-12-01

    A brief account of the present status of the recent nonlocal generalization of Einstein's theory of gravitation is presented. The main physical assumptions that underlie this theory are described. We clarify the physical meaning and significance of Weitzenbock's torsion and emphasize its intimate relationship with the gravitational field, characterized by the Riemannian curvature of spacetime. In this theory, nonlocality can simulate dark matter; in fact, in the Newtonian regime, we recover the phenomenological Tohline-Kuhn approach to modified gravity. To account for the observational data regarding dark matter, nonlocality is associated with a characteristic length scale of order 1 kpc. The confrontation of nonlocal gravity with observation is briefly discussed.

  4. Generalized tonic-clonic seizure

    MedlinePlus

    ... Seizure - grand mal; Grand mal seizure; Seizure - generalized; Epilepsy - generalized seizure ... occur as part of a repeated, chronic illness (epilepsy). Some seizures are due to psychological problems (psychogenic).

  5. General Healthcare Maintenance of IBD

    MedlinePlus

    ... health care provider about other important issues including: Vaccinations: Adults with IBD should generally follow the same vaccination schedules as the general population. The only exceptions ...

  6. General composite Higgs models

    NASA Astrophysics Data System (ADS)

    Marzocca, David; Serone, Marco; Shu, Jing

    2012-08-01

    We construct a general class of pseudo-Goldstone composite Higgs models, within the minimal SO(5)/SO(4) coset structure, that are not necessarily of moose-type. We characterize the main properties these models should have in order to give rise to a Higgs mass around 125 GeV. We assume the existence of relatively light and weakly coupled spin 1 and 1/2 resonances. In absence of a symmetry principle, we introduce the Minimal Higgs Potential (MHP) hypothesis: the Higgs potential is assumed to be one-loop dominated by the SM fields and the above resonances, with a contribution that is made calculable by imposing suitable generalizations of the first and second Weinberg sum rules. We show that a 125 GeV Higgs requires light, often sub-TeV, fermion resonances. Their presence can also be important for the models to successfully pass the electroweak precision tests. Interestingly enough, the latter can also be passed by models with a heavy Higgs around 320 GeV. The composite Higgs models of the moose-type considered in the literature can be seen as particular limits of our class of models.

  7. Functional Generalized Additive Models.

    PubMed

    McLean, Mathew W; Hooker, Giles; Staicu, Ana-Maria; Scheipl, Fabian; Ruppert, David

    2014-01-01

    We introduce the functional generalized additive model (FGAM), a novel regression model for association studies between a scalar response and a functional predictor. We model the link-transformed mean response as the integral with respect to t of F{X(t), t} where F(·,·) is an unknown regression function and X(t) is a functional covariate. Rather than having an additive model in a finite number of principal components as in Müller and Yao (2008), our model incorporates the functional predictor directly and thus our model can be viewed as the natural functional extension of generalized additive models. We estimate F(·,·) using tensor-product B-splines with roughness penalties. A pointwise quantile transformation of the functional predictor is also considered to ensure each tensor-product B-spline has observed data on its support. The methods are evaluated using simulated data and their predictive performance is compared with other competing scalar-on-function regression alternatives. We illustrate the usefulness of our approach through an application to brain tractography, where X(t) is a signal from diffusion tensor imaging at position, t, along a tract in the brain. In one example, the response is disease-status (case or control) and in a second example, it is the score on a cognitive test. R code for performing the simulations and fitting the FGAM can be found in supplemental materials available online. PMID:24729671

  8. General Aviation Data Framework

    NASA Technical Reports Server (NTRS)

    Blount, Elaine M.; Chung, Victoria I.

    2006-01-01

    The Flight Research Services Directorate at the NASA Langley Research Center (LaRC) provides development and operations services associated with three general aviation (GA) aircraft used for research experiments. The GA aircraft includes a Cessna 206X Stationair, a Lancair Colombia 300X, and a Cirrus SR22X. Since 2004, the GA Data Framework software was designed and implemented to gather data from a varying set of hardware and software sources as well as enable transfer of the data to other computers or devices. The key requirements for the GA Data Framework software include platform independence, the ability to reuse the framework for different projects without changing the framework code, graphics display capabilities, and the ability to vary the interfaces and their performance. Data received from the various devices is stored in shared memory. This paper concentrates on the object oriented software design patterns within the General Aviation Data Framework, and how they enable the construction of project specific software without changing the base classes. The issues of platform independence and multi-threading which enable interfaces to run at different frame rates are also discussed in this paper.

  9. Generalized gamma frailty model.

    PubMed

    Balakrishnan, N; Peng, Yingwei

    2006-08-30

    In this article, we present a frailty model using the generalized gamma distribution as the frailty distribution. It is a power generalization of the popular gamma frailty model. It also includes other frailty models such as the lognormal and Weibull frailty models as special cases. The flexibility of this frailty distribution makes it possible to detect a complex frailty distribution structure which may otherwise be missed. Due to the intractable integrals in the likelihood function and its derivatives, we propose to approximate the integrals either by Monte Carlo simulation or by a quadrature method and then determine the maximum likelihood estimates of the parameters in the model. We explore the properties of the proposed frailty model and the computation method through a simulation study. The study shows that the proposed model can potentially reduce errors in the estimation, and that it provides a viable alternative for correlated data. The merits of proposed model are demonstrated in analysing the effects of sublingual nitroglycerin and oral isosorbide dinitrate on angina pectoris of coronary heart disease patients based on the data set in Danahy et al. (sustained hemodynamic and antianginal effect of high dose oral isosorbide dinitrate. Circulation 1977; 55:381-387). PMID:16220516

  10. Mechanisms of general anesthesia.

    PubMed Central

    Franks, N P; Lieb, W R

    1990-01-01

    Although general anesthetics are often said to be nonspecific agents, it is likely that they act at a much more restricted set of target sites than commonly believed. The traditional view has been that the primary targets are lipid portions of nerve membranes, but recent evidence shows that the effects on lipid bilayers of clinically relevant levels of anesthetics are very small. Effects on most proteins are also small, but there are notable examples of proteins that are extremely sensitive to anesthetics and mimic the pharmacological profile of anesthetic target sites in animals. Such target sites are amphiphilic in nature, having both hydrophobic and polar components. The polar components appear to behave as good hydrogen-bond acceptors but poor hydrogen-bond donors. Although the targets can accept molecules with a wide variety of shapes and chemical groupings, they are unaffected by molecules exceeding a certain size. Overall, the data can be explained by supposing that the primary target sites underlying general anesthesia are amphiphilic pockets of circumscribed dimensions on particularly sensitive proteins in the central nervous system. PMID:2269226

  11. Closed-Form Solutions for a Circular Tunnel in Elastic-Brittle-Plastic Ground with the Original and Generalized Hoek-Brown Failure Criteria

    NASA Astrophysics Data System (ADS)

    Chen, Ran; Tonon, Fulvio

    2011-03-01

    The paper presents a closed-form solution for the convergence curve of a circular tunnel in an elasto-brittle-plastic rock mass with both the Hoek-Brown and generalized Hoek-Brown failure criteria, and a linear flow rule, i.e., the ratio between the minor and major plastic strain increments is constant. The improvement over the original solution of Brown et al. (J Geotech Eng ASCE 109(1):15-39, 1983) consists of taking into account the elastic strain variation in the plastic annulus, which was assumed to be fixed in the original solution by Brown et al. The improvement over Carranza-Torres' solution (Int J Rock Mech Min Sci 41(Suppl 1):629-639, 2004) consists of providing a closed-form solution, rather than resorting to numerical integration of an ordinary differential equation. The presented solution, by rigorously following the theory of plasticity, takes into account that the elastic strain components change with radial and circumferential stress changes within the plastic annulus. For the original Hoek-Brown failure criterion, disregarding the elastic strain change leads to underestimate the convergence by up to 55%. For a rock mass failing according to the generalized Hoek-Brown failure criterion, using the original failure criterion leads to a high probability (97%) of underestimating the convergence by up to 100%. As a consequence, the onset or degree of squeezing may be underestimated, and the loading on the support/reinforcement calculated with the convergence/confinement method may be largely underestimated.

  12. General airplane performance

    NASA Technical Reports Server (NTRS)

    Rockfeller, W C

    1939-01-01

    Equations have been developed for the analysis of the performance of the ideal airplane, leading to an approximate physical interpretation of the performance problem. The basic sea-level airplane parameters have been generalized to altitude parameters and a new parameter has been introduced and physically interpreted. The performance analysis for actual airplanes has been obtained in terms of the equivalent ideal airplane in order that the charts developed for use in practical calculations will for the most part apply to any type of engine-propeller combination and system of control, the only additional material required consisting of the actual engine and propeller curves for propulsion unit. Finally, a more exact method for the calculation of the climb characteristics for the constant-speed controllable propeller is presented in the appendix.

  13. Generalized entanglement entropy

    NASA Astrophysics Data System (ADS)

    Taylor, Marika

    2016-07-01

    We discuss two measures of entanglement in quantum field theory and their holographic realizations. For field theories admitting a global symmetry, we introduce a global symmetry entanglement entropy, associated with the partitioning of the symmetry group. This quantity is proposed to be related to the generalized holographic entanglement entropy defined via the partitioning of the internal space of the bulk geometry. Thesecond measure of quantum field theory entanglement is the field space entanglement entropy, obtained by integrating out a subset of the quantum fields. We argue that field space entanglement entropy cannot be precisely realised geometrically in a holographic dual. However, for holographic geometries with interior decoupling regions, the differential entropy provides a close analogue to the field space entanglement entropy. We derive generic descriptions of such inner throat regions in terms of gravity coupled to massive scalars and show how the differential entropy in the throat captures features of the field space entanglement entropy.

  14. Generalized quantum secret sharing

    SciTech Connect

    Singh, Sudhir Kumar; Srikanth, R.

    2005-01-01

    We explore a generalization of quantum secret sharing (QSS) in which classical shares play a complementary role to quantum shares, exploring further consequences of an idea first studied by Nascimento, Mueller-Quade, and Imai [Phys. Rev. A 64, 042311 (2001)]. We examine three ways, termed inflation, compression, and twin thresholding, by which the proportion of classical shares can be augmented. This has the important application that it reduces quantum (information processing) players by replacing them with their classical counterparts, thereby making quantum secret sharing considerably easier and less expensive to implement in a practical setting. In compression, a QSS scheme is turned into an equivalent scheme with fewer quantum players, compensated for by suitable classical shares. In inflation, a QSS scheme is enlarged by adding only classical shares and players. In a twin-threshold scheme, we invoke two separate thresholds for classical and quantum shares based on the idea of information dilution.

  15. Generalized teleportation protocol

    SciTech Connect

    Gordon, Goren; Rigolin, Gustavo

    2006-04-15

    A generalized teleportation protocol (GTP) for N qubits is presented, where the teleportation channels are nonmaximally entangled and all the free parameters of the protocol are considered: Alice's measurement basis, her sets of acceptable results, and Bob's unitary operations. The full range of fidelity (F) of the teleported state and the probability of success (P{sub suc}) to obtain a given fidelity are achieved by changing these free parameters. A channel efficiency bound is found, where one can determine how to divide it between F and P{sub suc}. A one-qubit formulation is presented and then expanded to N qubits. A proposed experimental setup that implements the GTP is given using linear optics.

  16. Generalized channeled polarimetry.

    PubMed

    Alenin, Andrey S; Tyo, J Scott

    2014-05-01

    Channeled polarimeters measure polarization by modulating the measured intensity in order to create polarization-dependent channels that can be demodulated to reveal the desired polarization information. A number of channeled systems have been described in the past, but their proposed designs often unintentionally sacrifice optimality for ease of algebraic reconstruction. To obtain more optimal systems, a generalized treatment of channeled polarimeters is required. This paper describes methods that enable handling of multi-domain modulations and reconstruction of polarization information using linear algebra. We make practical choices regarding use of either Fourier or direct channels to make these methods more immediately useful. Employing the introduced concepts to optimize existing systems often results in superficial system changes, like changing the order, orientation, thickness, or spacing of polarization elements. For the two examples we consider, we were able to reduce noise in the reconstruction to 34.1% and 57.9% of the original design values. PMID:24979633

  17. Neutron stars - General review

    NASA Technical Reports Server (NTRS)

    Cameron, A. G. W.; Canuto, V.

    1974-01-01

    A review is presented of those properties of neutron stars upon which there is general agreement and of those areas which currently remain in doubt. Developments in theoretical physics of neutron star interiors are summarized with particular attention devoted to hyperon interactions and the structure of interior layers. Determination of energy states and the composition of matter is described for successive layers, beginning with the surface and proceeding through the central region into the core. Problems encountered in determining the behavior of matter in the ultra-high density regime are discussed, and the effects of the magnetic field of a neutron star are evaluated along with the behavior of atomic structures in the field. The evolution of a neutron star is outlined with discussion centering on carbon detonation, cooling, vibrational damping, rotation, and pulsar glitches. The role of neutron stars in cosmic-ray propagation is considered.

  18. Generalized gravitational entropy

    NASA Astrophysics Data System (ADS)

    Lewkowycz, Aitor; Maldacena, Juan

    2013-08-01

    We consider classical Euclidean gravity solutions with a boundary. The boundary contains a non-contractible circle. These solutions can be interpreted as computing the trace of a density matrix in the full quantum gravity theory, in the classical approximation. When the circle is contractible in the bulk, we argue that the entropy of this density matrix is given by the area of a minimal surface. This is a generalization of the usual black hole entropy formula to euclidean solutions without a Killing vector. A particular example of this set up appears in the computation of the entanglement entropy of a subregion of a field theory with a gravity dual. In this context, the minimal area prescription was proposed by Ryu and Takayanagi. Our arguments explain their conjecture.

  19. [General aspects of homeopathy].

    PubMed

    Avello L, Marcia; Avendaño O, Cristian; Mennickent C, Sigrid

    2009-01-01

    Homeopathic medicine is a type of therapy that appeared in Europe at the end of the eighteenth century. At the present time, it is widely accepted in developed countries as a form of alternative medicine. In Chile, health regulation includes homeopathy as pharmaceutical products and homeopathy is also considered a form of complementary medicine, that is well accepted by the public. The scientific rationale of homeopathy is based on an empiric type of thought that goes from the general to the particular. The symptoms that are valued are those that are particular to each sick individual. It uses diluted solutions of plants, minerals, animals and even venoms. There are basically two hypotheses to explain its mechanisms of action: The "immunological memory" and the "memory of water" or the transmission of electromagnetic information of the water. There still is needed to perform new studies to scientifically assess homeopathy and its usefulness, as an accepted alternative therapy. PMID:19399332

  20. General linear chirplet transform

    NASA Astrophysics Data System (ADS)

    Yu, Gang; Zhou, Yiqi

    2016-03-01

    Time-frequency (TF) analysis (TFA) method is an effective tool to characterize the time-varying feature of a signal, which has drawn many attentions in a fairly long period. With the development of TFA, many advanced methods are proposed, which can provide more precise TF results. However, some restrictions are introduced inevitably. In this paper, we introduce a novel TFA method, termed as general linear chirplet transform (GLCT), which can overcome some limitations existed in current TFA methods. In numerical and experimental validations, by comparing with current TFA methods, some advantages of GLCT are demonstrated, which consist of well-characterizing the signal of multi-component with distinct non-linear features, being independent to the mathematical model and initial TFA method, allowing for the reconstruction of the interested component, and being non-sensitivity to noise.

  1. Finding General Dyke.

    PubMed

    Dyke, Charles William; Dyke, Ann Bisconti

    2011-01-01

    A hemorrhagic stroke and aphasia suddenly changed the life of Charles William (Bill) Dyke, Army Lt. General (Retired), Ranger strong with 2 silver stars and 3 bronze stars among his many decorations and founder and CEO of a Washington, DC, consulting firm. Gen. Dyke and his wife Ann provide their personal perspectives on the path to his remarkable recovery and return to full-time work. They found that the most effective therapy linked to who he was and is. Standard therapy tools and impersonal approaches frequently created barriers. Instead, when health professionals related the therapy objectives to his interests and involved him in the process of setting objectives to meet the challenges, they gained his trust, cooperation, participation, and focus on learning. PMID:21447463

  2. Generalized convexity and inequalities

    NASA Astrophysics Data System (ADS)

    Anderson, G. D.; Vamanamurthy, M. K.; Vuorinen, M.

    2007-11-01

    Let and let be the family of all mean values of two numbers in (some examples are the arithmetic, geometric, and harmonic means). Given , we say that a function is (m1,m2)-convex if f(m1(x,y))[less-than-or-equals, slant]m2(f(x),f(y)) for all . The usual convexity is the special case when both mean values are arithmetic means. We study the dependence of (m1,m2)-convexity on m1 and m2 and give sufficient conditions for (m1,m2)-convexity of functions defined by Maclaurin series. The criteria involve the Maclaurin coefficients. Our results yield a class of new inequalities for several special functions such as the Gaussian hypergeometric function and a generalized Bessel function.

  3. Generalized mid dermal elastolysis

    PubMed Central

    Cruz, Maria João; Barros, Ana Margarida; Azevedo, Filomena

    2011-01-01

    Mid-dermal elastolysis (MDE) is a rare skin disorder clinically characterized by the appearance of diffuse fine wrinkling, most often of the trunk and arms. This entity is distinguished from other elastolytic disorders by its characteristic selective loss of elastic fibers of the mid dermis. The aetiopathogenesis of the disease is still unclear as well as the effective treatment. Half of the cases described in the literature are associated with ultraviolet radiation exposure. Other reported triggering conditions such as urticaria, eczema and granuloma annulare suggests different eliciting inflammatory pathways. The authors describe the case of a 38-year-old woman who developed an urticarial eruption during months which progressed to generalized and severe fine wrinkling. PMID:25386304

  4. Ocean General Circulation Models

    SciTech Connect

    Yoon, Jin-Ho; Ma, Po-Lun

    2012-09-30

    1. Definition of Subject The purpose of this text is to provide an introduction to aspects of oceanic general circulation models (OGCMs), an important component of Climate System or Earth System Model (ESM). The role of the ocean in ESMs is described in Chapter XX (EDITOR: PLEASE FIND THE COUPLED CLIMATE or EARTH SYSTEM MODELING CHAPTERS). The emerging need for understanding the Earth’s climate system and especially projecting its future evolution has encouraged scientists to explore the dynamical, physical, and biogeochemical processes in the ocean. Understanding the role of these processes in the climate system is an interesting and challenging scientific subject. For example, a research question how much extra heat or CO2 generated by anthropogenic activities can be stored in the deep ocean is not only scientifically interesting but also important in projecting future climate of the earth. Thus, OGCMs have been developed and applied to investigate the various oceanic processes and their role in the climate system.

  5. Generalized conjugate gradient squared

    SciTech Connect

    Fokkema, D.R.; Sleijpen, G.L.G.

    1994-12-31

    In order to solve non-symmetric linear systems of equations, the Conjugate Gradient Squared (CGS) is a well-known and widely used iterative method. In practice the method converges fast, often twice as fast as the Bi-Conjugate Gradient method. This is what you may expect, since CGS uses the square of the BiCG polynomial. However, CGS may suffer from its erratic convergence behavior. The method may diverge or the approximate solution may be inaccurate. BiCGSTAB uses the BiCG polynomial and a product of linear factors in an attempt to smoothen the convergence. In many cases, this has proven to be very effective. Unfortunately, the convergence of BiCGSTAB may stall when a linear factor (nearly) degenerates. BiCGstab({ell}) is designed to overcome this degeneration of linear factors. It generalizes BiCGSTAB and uses both the BiCG polynomial and a product of higher order factors. Still, CGS may converge faster than BiCGSTAB or BiCGstab({ell}). So instead of using a product of linear or higher order factors, it may be worthwhile to look for other polynomials. Since the BiCG polynomial is based on a three term recursion, a natural choice would be a polynomial based on another three term recursion. Possibly, a suitable choice of recursion coefficients would result in method that converges faster or as fast as CGS, but less erratic. It turns out that an algorithm for such a method can easily be formulated. One particular choice for the recursion coefficients leads to CGS. Therefore one could call this algorithm generalized CGS. Another choice for the recursion coefficients leads to BiCGSTAB. It is therefore possible to mix linear factors and some polynomial based on a three term recursion. This way one may get the best of both worlds. The authors will report on their findings.

  6. Generalizing Contextual Analysis.

    PubMed

    Bourrat, Pierrick

    2016-06-01

    Okasha, in Evolution and the Levels of Selection, convincingly argues that two rival statistical decompositions of covariance, namely contextual analysis and the neighbour approach, are better causal decompositions than the hierarchical Price approach. However, he claims that this result cannot be generalized in the special case of soft selection and argues that the Price approach represents in this case a better option. He provides several arguments to substantiate this claim. In this paper, I demonstrate that these arguments are flawed and argue that neither the Price equation nor the contextual and neighbour partitionings sensu Okasha are adequate causal decompositions in cases of soft selection. The Price partitioning is generally unable to detect cross-level by-products and this naturally also applies to soft selection. Both contextual and neighbour partitionings violate the fundamental principle of determinism that the same cause always produces the same effect. I argue that a fourth partitioning widely used in the contemporary social sciences, under the generic term of 'hierarchical linear model' and related to contextual analysis understood broadly, addresses the shortcomings of the three other partitionings and thus represents a better causal decomposition. I then defend this model against the argument that because it predicts that there is some organismal selection in some specific cases of segregation distortion then it should be rejected. I show that cases of segregation distortion that intuitively seem to contradict the conclusion drawn from the hierarchical linear model are in fact cases of multilevel selection 2 while the assessment of the different partitionings are restricted to multilevel selection 1. PMID:27230419

  7. Special and general superatoms.

    PubMed

    Luo, Zhixun; Castleman, A Welford

    2014-10-21

    of application of the jellium model and modification of the theory to account for nonspherical symmetry and nonmetal-doped metal clusters are still illusive to be further developed. It is still worth mentioning that a superatom concept has also been introduced in ligand-stabilized metal clusters which could also follow the major shell-closing electron count for a spherical, square-well potential. By proposing a new concept named as special and general superatoms, herein we try to summarize all these investigations in series, expecting to provide an overview of this field with a primary focus on the joint undertakings which have given rise to the superatom concept. To be specific, for special superatoms, we limit to clusters under a strict jellium model and simply classify them into groups based on their valence electron counts. While for general superatoms we emphasize on nonmetal-doped metal clusters and ligand-stabilized metal clusters, as well as a few isovalent cluster systems. Hopefully this summary of special and general superatoms benefits the further development of cluster-related theory, and lights up the prospect of using them as building blocks of new materials with tailored properties, such as inexpensive isovalent systems for industrial catalysis, semiconductive superatoms for transistors, and magnetic superatoms for spin electronics. PMID:25252219

  8. Generalized emissivity inverse problem.

    PubMed

    Ming, DengMing; Wen, Tao; Dai, XianXi; Dai, JiXin; Evenson, William E

    2002-04-01

    Inverse problems have recently drawn considerable attention from the physics community due to of potential widespread applications [K. Chadan and P. C. Sabatier, Inverse Problems in Quantum Scattering Theory, 2nd ed. (Springer Verlag, Berlin, 1989)]. An inverse emissivity problem that determines the emissivity g(nu) from measurements of only the total radiated power J(T) has recently been studied [Tao Wen, DengMing Ming, Xianxi Dai, Jixin Dai, and William E. Evenson, Phys. Rev. E 63, 045601(R) (2001)]. In this paper, a new type of generalized emissivity and transmissivity inverse (GETI) problem is proposed. The present problem differs from our previous work on inverse problems by allowing the unknown (emissivity) function g(nu) to be temperature dependent as well as frequency dependent. Based on published experimental information, we have developed an exact solution formula for this GETI problem. A universal function set suggested for numerical calculation is shown to be robust, making this inversion method practical and convenient for realistic calculations. PMID:12005916

  9. Generalized Linear Covariance Analysis

    NASA Technical Reports Server (NTRS)

    Carpenter, James R.; Markley, F. Landis

    2014-01-01

    This talk presents a comprehensive approach to filter modeling for generalized covariance analysis of both batch least-squares and sequential estimators. We review and extend in two directions the results of prior work that allowed for partitioning of the state space into solve-for'' and consider'' parameters, accounted for differences between the formal values and the true values of the measurement noise, process noise, and textita priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator's epoch time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the variance sandpile'' and the sensitivity mosaic,'' and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.

  10. Generalized reduced MHD equations

    SciTech Connect

    Kruger, S.E.; Hegna, C.C.; Callen, J.D.

    1998-07-01

    A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general toroidal configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson.

  11. Generalized Effective Radiance Temperature

    NASA Astrophysics Data System (ADS)

    Yuan, Z.

    2015-12-01

    Radiance temperature is one of the most important and widely used concepts in radiation thermometry. The usual definition of radiance temperature does not strictly apply for complex situations, such as when surrounding radiation is non-negligible or when corrections are applied to measurements made using an inappropriate emissivity setting. A novel concept, generalized effective radiance temperature (GERT), that adopts a graybody as the reference radiator is proposed in this study to express and explain the actual measurands that exist extensively in practical radiation thermometry applications; for example, a measurement result by a spectral-band radiation thermometer whose instrumental emissivity setting is less than 1. An effective wavelength approach has been developed to elucidate the relationship between a thermometer-dependent temperature (reading from an actual spectral-band radiation thermometer) and the object-side parameter GERT. The characteristics of GERT and the effective wavelength of a GERT measurement are discussed. Choosing an arbitrary emissivity setting to correct for the emissivity of a real target is equivalent to using this value as the emissivity of the reference graybody of the GERT. The GERT can be used in calibrations of both sources and thermometers.

  12. Generalized teleparallel theory

    NASA Astrophysics Data System (ADS)

    Junior, Ednaldo L. B.; Rodrigues, Manuel E.

    2016-07-01

    We construct a theory in which the gravitational interaction is described only by torsion, but that generalizes the teleparallel theory still keeping the invariance of local Lorentz transformations in one particular case. We show that our theory falls, in a certain limit of a real parameter, under f(bar{R}) gravity or, in another limit of the same real parameter, under modified f( T) gravity; on interpolating between these two theories it still can fall under several other theories. We explicitly show the equivalence with f(bar{R}) gravity for the cases of a Friedmann-Lemaître-Robertson-Walker flat metric for diagonal tetrads, and a metric with spherical symmetry for diagonal and non-diagonal tetrads. We study four applications, one in the reconstruction of the de Sitter universe cosmological model, for obtaining a static spherically symmetric solution of de Sitter type for a perfect fluid, for evolution of the state parameter ω _{DE}, and for the thermodynamics of the apparent horizon.

  13. Generalized Canonical Time Warping.

    PubMed

    Zhou, Feng; De la Torre, Fernando

    2016-02-01

    Temporal alignment of human motion has been of recent interest due to its applications in animation, tele-rehabilitation and activity recognition. This paper presents generalized canonical time warping (GCTW), an extension of dynamic time warping (DTW) and canonical correlation analysis (CCA) for temporally aligning multi-modal sequences from multiple subjects performing similar activities. GCTW extends previous work on DTW and CCA in several ways: (1) it combines CCA with DTW to align multi-modal data (e.g., video and motion capture data); (2) it extends DTW by using a linear combination of monotonic functions to represent the warping path, providing a more flexible temporal warp. Unlike exact DTW, which has quadratic complexity, we propose a linear time algorithm to minimize GCTW. (3) GCTW allows simultaneous alignment of multiple sequences. Experimental results on aligning multi-modal data, facial expressions, motion capture data and video illustrate the benefits of GCTW. The code is available at http://humansensing.cs.cmu.edu/ctw. PMID:26761734

  14. Generalized Multicoincidence Analysis Methods

    SciTech Connect

    Warren, Glen A.; Smith, Leon E.; Aalseth, Craig E.; Ellis, J. E.; Valsan, Andrei B.; Mengesha, Wondwosen

    2005-10-01

    The ability to conduct automated trace radionuclide analysis at or near the sample collection point would provide a valuable tool for emergency response, nuclear forensics and environmental monitoring. Pacific Northwest National Laboratory is developing systems for this purpose based on dual gamma-ray spectrometers, e.g. NaI(TI) or HPGe, combined with thin organic scintillator sensors to detect light charged particles. Translating the coincident signatures recorded by these systems, which include , and , into the concentration of detectable radionuclides in the sample requires generalized multicoincidence analysis tools. The development and validation of the Coincidence Lookup Library, which currently contains the probabilities of single and coincidence signatures from more than 420 isotopes, is described. Also discussed is a method to calculate the probability of observing a coincidence signature which incorporates true coincidence summing effects. These effects are particularly important for high-geometric-efficiency detection systems. Finally, a process for validating the integrated analysis software package is demonstrated using GEANT 4 simulations of the prototype detector systems.

  15. Generalized Multicoincidence Analysis Methods

    SciTech Connect

    Warren, Glen A.; Smith, Leon E.; Aalseth, Craig E.; Ellis, J. E.; Valsan, Andrei B.; Mengesha, Wondwosen

    2006-02-01

    The ability to conduct automated trace radionuclide analysis at or near the sample collection point would provide a valuable tool for emergency response, environmental monitoring, and verification of treaties and agreements. Pacific Northwest National Laboratory is developing systems for this purpose based on dual gamma-ray spectrometers, e.g. NaI(TI) or HPGe, combined with thin organic scintillator sensors to detect light charged particles. Translating the coincident signatures recorded by these systems, which include beta-gamma, gamma-gamma and beta-gamma-gamma, into the concentration of detectable radionuclides in the sample requires generalized multicoincidence analysis tools. The development and validation of the Coincidence Lookup Library, which currently contains the probabilities of single and coincidence signatures from more than 420 isotopes, is described. Also discussed is a method to calculate the probability of observing a coincidence signature which incorporates true coincidence summing effects. These effects are particularly important for high-geometric-efficiency detection systems. Finally, a process for verifying the integrated analysis software package is demonstrated using GEANT 4 simulations of the prototype detector systems.

  16. General defocusing particle tracking.

    PubMed

    Barnkob, Rune; Kähler, Christian J; Rossi, Massimiliano

    2015-09-01

    A General Defocusing Particle Tracking (GDPT) method is proposed for tracking the three-dimensional motion of particles in Lab-on-a-chip systems based on a set of calibration images and the normalized cross-correlation function. In comparison with other single-camera defocusing particle-tracking techniques, GDPT possesses a series of key advantages: it is applicable to particle images of arbitrary shapes, it is intuitive and easy to use, it can be used without advanced knowledge of optics and velocimetry theory, it is robust against outliers and overlapping particle images, and it requires only equipment which is standard in microfluidic laboratories. We demonstrate the method by tracking the three-dimensional motion of 2 μm spherical particles in a microfluidic channel using three different optical arrangements. The position of the particles was measured with an estimated uncertainty of 0.1 μm in the in-plane direction and 2 μm in the depth direction for a measurement volume of 1510 × 1270 × 160 μm(3). A ready-to-use GUI implementation of the method can be acquired on . PMID:26201498

  17. Generalized Linear Covariance Analysis

    NASA Technical Reports Server (NTRS)

    Carpenter, J. Russell; Markley, F. Landis

    2008-01-01

    We review and extend in two directions the results of prior work on generalized covariance analysis methods. This prior work allowed for partitioning of the state space into "solve-for" and "consider" parameters, allowed for differences between the formal values and the true values of the measurement noise, process noise, and a priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and a priori solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator s anchor time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the "variance sandpile" and the "sensitivity mosaic," and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.

  18. Generalized reduced magnetohydrodynamic equations

    SciTech Connect

    Kruger, S.E.

    1999-02-01

    A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-Alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson. The equations have been programmed into a spectral initial value code and run with shear flow that is consistent with the equilibrium input into the code. Linear results of tearing modes with shear flow are presented which differentiate the effects of shear flow gradients in the layer with the effects of the shear flow decoupling multiple harmonics.

  19. Obesity in general practice

    PubMed Central

    Malterud, Kirsti; Ulriksen, Kjersti

    2010-01-01

    Objective To explore obese patients' experiences with GPs' management of their weight problems. Methods Focus-group study with a purposive sample of 13 participants (eight women and five men), aged 30–55 years, with BMI above 40, or BMI above 35 with additional weight-related problems. Two focus-group interviews were conducted, inviting the participants to speak about their health care experiences from general practice. Analysis applied Systematic Text Condensation inspired by Giorgi's approach, searching for issues describing or discussing participants' experiences of GPs' obesity management. Results Obese patients want their GPs to put their weight problems on the agenda. When the patient appears reluctant, it may be a sign of embarrassment rather than rejection of the issue. However, restricted attention to obesity could lead to neglect of patients' problems. Participants complained that GPs often demonstrated insufficient engagement and knowledge regarding service resources for obesity treatment, leaving the responsibility for information on available referral resources to the patient. Finally, considerate attitudes in the GPs are needed for follow-up to be experienced as helpful by the patients. Vulnerable feelings of failure could be reinforced by well-intended advice. Degrading attitudes were perceived as especially subversive when they came from doctors. Conclusions The challenge for the GP is to increase his or her competence in individualized and evidence-based counselling, while acknowledging the efforts needed by the patient to achieve permanent change, and shifting attention from shame to coping. PMID:20942741

  20. The Madden-Julian Oscillation in General Circulation Models

    SciTech Connect

    Sperber, K R; Gleckler, P J; Doutriaux, C; Groups, A M; Groups, C M; Slingo, J M; Inness, P M; Gualdi, S; Li, W

    2003-10-27

    A methodology is utilized to analyze in a standardized fashion the Madden-Julian Oscillation (MJO) in general circulation models. This is attained by projecting 20-100 day bandpass filtered outgoing longwave radiation (OLR) from the models onto the two leading empirical orthogonal functions (EOF's) of observed OLR that characterize the propagation of MJO convection from the Indian Ocean to the central Pacific Ocean. The resulting principal component time series are then screened to isolate boreal winters during which they exhibit a lead-lag relationship consistent with observations. This PC subset is used for linear regression to determine the ability of the models to simulate the observed spacetime variability of the MJO. The vast majority of models underestimate the amplitude of the MJO convective anomalies by a factor of two or more, and the eastward propagation of convection is less coherent than observed, typically. For a given family of models, coupling to an ocean leads to better organization of the large-scale convection. The low-level moisture convergence mechanism for eastward propagation is represented in limited cases, as is the vertical structure of the MJO.

  1. 2. General view to southwest, showing general context at low ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. General view to southwest, showing general context at low tide, with Building 24 in background right. - Charlestown Navy Yard, Marine Railway, Between Piers 2 & 3, on Charlestown Waterfront at west end of Navy Yard, Boston, Suffolk County, MA

  2. Action principle for the generalized harmonic formulation of general relativity

    SciTech Connect

    Brown, J. David

    2011-10-15

    An action principle for the generalized harmonic formulation of general relativity is presented. The action is a functional of the spacetime metric and the gauge source vector. An action principle for the Z4 formulation of general relativity has been proposed recently by Bona, Bona-Casas, and Palenzuela. The relationship between the generalized harmonic action and the Bona, Bona-Casas, and Palenzuela action is discussed in detail.

  3. Directions in General Relativity

    NASA Astrophysics Data System (ADS)

    Hu, B. L.; Ryan, M. P., Jr.; Vishveshwara, C. V.

    2005-10-01

    Preface; Dieter Brill: a spacetime perspective; 1. Thawing the frozen formalism: the difference between observables and what we observe A. Anderson; 2. Jacobi's action and the density of states J. D. Brown and J. W. York; 3. Decoherence of correlation histories E. Calzetta and B. L. Hu; 4. The initial value problem in light of Ashtekar's variables R. Capovilla, J. Dell and T. Jacobson; 5. Status report on an axiomatic basis for functional integration P. Cartier and C. DeWitt-Morette; 6. Solution of the coupled Einstein constraints on asymptotically Euclidean manifolds Y. Choquet-Bruhat; 7. Compact Cauchy horizons and Cauchy surfaces P. Chrusciel and J. Isenberg; 8. The classical electron J. M. Cohen and E. Mustafa; 9. Gauge (in)variance, mass and parity in D=3 revisited S. Deser; 10. Triality, exceptional Lie groups and Dirac operators F. Flaherty; 11. The reduction of the state vector and limitations on measurement in the quantum mechanics of closed systems J. B. Hartle; 12 Quantum linearization instabilities of de Sitter spacetime A. Higuchi; 13. What is the true description of charged black holes? G. T. Horowitz; 14. Limits on the adiabatic index in static stellar models L. Lindblom and A. K. M. Masood-ul-Alam; 15. On the relativity of rotation B. Mashhoon; 16. Recent progress and open problems in linearization stability V. E. Moncrief; 17. Brill waves N. Ó Murchadha; 18. You can't get there from here: constraints on topology change K. Schleich and D. M. Witt; 19. Time, measurement and information loss in quantum cosmology L. Smolin; 20. Impossible measurements on quantum fields R. Sorkin; 21. A new condition implying the existence of a constant mean curvature foliation F. J. Tipler; 22. Maximal slices in stationary spacetimes with ergoregions R. M. Wald; 23. (1 + 1) - Dimensional methods for general relativity J. H. Yoon; 24. Coalescence of primal gravity waves to make cosmological mass without matter D. E. Holz, W. A. Miller, M. Wakano and J. A. Wheeler.

  4. Aquaglyceroporins: generalized metalloid channels

    PubMed Central

    Mukhopadhyay, Rita; Bhattacharjee, Hiranmoy; Rosen, Barry P.

    2014-01-01

    Background: Aquaporins (AQPs), members of a superfamily of transmembrane channel proteins, are ubiquitous in all domains of life. They fall into a number of branches that can be functionally categorized into two major sub-groups: i) orthodox aquaporins, which are water-specific channels, and ii) aquaglyceroporins, which allow the transport of water, non-polar solutes, such as urea or glycerol, the reactive oxygen species hydrogen peroxide, and gases such as ammonia, carbon dioxide and nitric oxide and, as described in this review, metalloids. Scope of Review: This review summarizes the key findings that AQP channels conduct bidirectional movement of metalloids into and out of cells. Major Conclusions: As(OH)3 and Sb(OH)3 behave as inorganic molecular mimics of glycerol, a property that allows their passage through AQP channels. Plant AQPs also allow the passage of boron and silicon as their hydroxyacids, boric acid (B(OH)3) and orthosilicic acid (Si(OH)4), respectively. Genetic analysis suggests that germanic acid (GeO2) is also a substrate. While As(III), Sb(III) and Ge(IV) are toxic metalloids, borate (B(III)) and silicate (Si(IV)) are essential elements in higher plants. General Significance: The uptake of environmental metalloids by aquaporins provides an understanding of (i) how toxic elements such as arsenic enter the food chain; (ii) the delivery of arsenic and antimony containing drugs in the treatment of certain forms of leukemia and chemotherapy of diseases caused by pathogenic protozoa; and (iii) the possibility that food plants such as rice could be made safer by genetically modifying them to exclude arsenic while still accumulating boron and silicon. PMID:24291688

  5. GVS - GENERAL VISUALIZATION SYSTEM

    NASA Technical Reports Server (NTRS)

    Keith, S. R.

    1994-01-01

    The primary purpose of GVS (General Visualization System) is to support scientific visualization of data output by the panel method PMARC_12 (inventory number ARC-13362) on the Silicon Graphics Iris computer. GVS allows the user to view PMARC geometries and wakes as wire frames or as light shaded objects. Additionally, geometries can be color shaded according to phenomena such as pressure coefficient or velocity. Screen objects can be interactively translated and/or rotated to permit easy viewing. Keyframe animation is also available for studying unsteady cases. The purpose of scientific visualization is to allow the investigator to gain insight into the phenomena they are examining, therefore GVS emphasizes analysis, not artistic quality. GVS uses existing IRIX 4.0 image processing tools to allow for conversion of SGI RGB files to other formats. GVS is a self-contained program which contains all the necessary interfaces to control interaction with PMARC data. This includes 1) the GVS Tool Box, which supports color histogram analysis, lighting control, rendering control, animation, and positioning, 2) GVS on-line help, which allows the user to access control elements and get information about each control simultaneously, and 3) a limited set of basic GVS data conversion filters, which allows for the display of data requiring simpler data formats. Specialized controls for handling PMARC data include animation and wakes, and visualization of off-body scan volumes. GVS is written in C-language for use on SGI Iris series computers running IRIX. It requires 28Mb of RAM for execution. Two separate hardcopy documents are available for GVS. The basic document price for ARC-13361 includes only the GVS User's Manual, which outlines major features of the program and provides a tutorial on using GVS with PMARC_12 data. Programmers interested in modifying GVS for use with data in formats other than PMARC_12 format may purchase a copy of the draft GVS 3.1 Software Maintenance

  6. Human factors in general aviation

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The relation of the pilot to the aircraft in general aviation is considered. The human component is analyzed, along with general aviation facilities. The man-machine interface, and the man-environment interface are discussed.

  7. General Information about Cervical Cancer

    MedlinePlus

    ... Research Cervical Cancer Treatment (PDQ®)–Patient Version General Information About Cervical Cancer Go to Health Professional Version ... the NCI website . Cervical Cancer During Pregnancy General Information About Cervical Cancer During Pregnancy Treatment of cervical ...

  8. [Manual therapy in general practice].

    PubMed

    Березуцкий, Владимир И

    2016-01-01

    The article is devoted to manual therapy practice for diagnostics and treatment of vertebrogenic pain syndrome in general practice. Analytical roundup of sources proves medical advantage of implementation of manual therapy basic methods by general practice specialists. PMID:27487550

  9. The Status of General Chemistry

    ERIC Educational Resources Information Center

    Brooks, David W.

    1977-01-01

    Presents the first of a series of papers discussing the major features and underlying philosophies of general college chemistry. This first paper reviews secondary level course content as well as college level general chemistry curricula. (SL)

  10. The General Factor of Personality: A General Critique

    PubMed Central

    Revelle, William; Wilt, Joshua

    2013-01-01

    Recently, it has been proposed that all non-cognitive measures of personality share a general factor of personality. A problem with many of these studies is a lack of clarity in defining a general factor. In this paper we address the multiple ways in which a general factor has been identified and argue that many of these approaches find factors that are not in fact general. Through the use of artificial examples, we show that a general factor is not: The first factor or component of a correlation or covariance matrix.The first factor resulting from a bifactor rotation or biquartimin transformationNecessarily the result of a confirmatory factor analysis forcing a bifactor solution We consider how the definition of what constitutes a general factor can lead to confusion, and we will demonstrate alternative ways of estimating the general factor saturation that are more appropriate. PMID:23956474

  11. The Generalized DINA Model Framework

    ERIC Educational Resources Information Center

    de la Torre, Jimmy

    2011-01-01

    The G-DINA ("generalized deterministic inputs, noisy and gate") model is a generalization of the DINA model with more relaxed assumptions. In its saturated form, the G-DINA model is equivalent to other general models for cognitive diagnosis based on alternative link functions. When appropriate constraints are applied, several commonly used…

  12. General Aviation Pilot Education Program.

    ERIC Educational Resources Information Center

    Cole, Warren L.

    General Aviation Pilot Education (GAPE) was a safety program designed to improve the aeronautical education of the general aviation pilot in anticipation that the national aircraft accident rate might be improved. GAPE PROGRAM attempted to reach the average general aviation pilot with specific and factual information regarding the pitfalls of his…

  13. Regularized Generalized Canonical Correlation Analysis

    ERIC Educational Resources Information Center

    Tenenhaus, Arthur; Tenenhaus, Michel

    2011-01-01

    Regularized generalized canonical correlation analysis (RGCCA) is a generalization of regularized canonical correlation analysis to three or more sets of variables. It constitutes a general framework for many multi-block data analysis methods. It combines the power of multi-block data analysis methods (maximization of well identified criteria) and…

  14. Generalized Multilevel Structural Equation Modeling

    ERIC Educational Resources Information Center

    Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

    2004-01-01

    A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…

  15. OLEDS FOR GENERAL LIGHTING

    SciTech Connect

    Anil Duggal; Don Foust; Chris Heller; Bill Nealon; Larry Turner; Joe Shiang; Nick Baynes; Tim Butler; Nalin Patel

    2004-02-29

    The goal of this program was to reduce the long term technical risks that were keeping the lighting industry from embracing and developing organic light-emitting diode (OLED) technology for general illumination. The specific goal was to develop OLEDs for lighting to the point where it was possible to demonstrate a large area white light panel with brightness and light quality comparable to a fluorescence source and with an efficacy comparable to that of an incandescent source. it was recognized that achieving this would require significant advances in three area: (1) the improvement of white light quality for illumination, (2) the improvement of OLED energy efficiency at high brightness, and (3) the development of cost-effective large area fabrication techniques. The program was organized such that, each year, a ''deliverable'' device would be fabricated which demonstrated progress in one or more of the three critical research areas. In the first year (2001), effort concentrated on developing an OLED capable of generating high illumination-quality white light. Ultimately, a down-conversion method where a blue OLED was coupled with various down-conversion layers was chosen. Various color and scattering models were developed to aid in material development and device optimization. The first year utilized this approach to deliver a 1 inch x 1 inch OLED with higher illumination-quality than available fluorescent sources. A picture of this device is shown and performance metrics are listed. To their knowledge, this was the first demonstration of true illumination-quality light from an OLED. During the second year, effort concentrated on developing a scalable approach to large area devices. A novel device architecture consisting of dividing the device area into smaller elements that are monolithically connected in series was developed. In the course of this development, it was realized that, in addition to being scalable, this approach made the device tolerant to the most

  16. Small bowel wall thickening: MDCT evaluation in the emergency room.

    PubMed

    Akcalar, Seray; Turkbey, Baris; Karcaaltincaba, Musturay; Akpinar, Erhan; Akhan, Okan

    2011-10-01

    Small bowel wall thickening detected on computed tomography is a frequent finding in patients referring to emergency room with acute abdominal pain. In this pictorial review, we aim to discuss patterns of small bowel wall thickening and to explain hints for differential diagnosis with imaging findings. PMID:21681404

  17. General aviation avionics equipment maintenance

    NASA Technical Reports Server (NTRS)

    Parker, C. D.; Tommerdahl, J. B.

    1978-01-01

    Maintenance of general aviation avionics equipment was investigated with emphasis on single engine and light twin engine general aviation aircraft. Factors considered include the regulatory agencies, avionics manufacturers, avionics repair stations, the statistical character of the general aviation community, and owners and operators. The maintenance, environment, and performance, repair costs, and reliability of avionics were defined. It is concluded that a significant economic stratification is reflected in the maintenance problems encountered, that careful attention to installations and use practices can have a very positive impact on maintenance problems, and that new technologies and a general growth in general aviation will impact maintenance.

  18. Telephone triage in general practices: A written case scenario study in the Netherlands

    PubMed Central

    Smits, Marleen; Hanssen, Suzan; Huibers, Linda; Giesen, Paul

    2016-01-01

    Objective General practices increasingly use telephone triage to manage patient flows. During triage, the urgency of the call and required type of care are determined. This study examined the organization and adequacy of telephone triage in general practices in the Netherlands. Design Cross-sectional observational study using a web-based survey among practice assistants including questions on background characteristics and triage organization. Furthermore, practice assistants were asked to assess the required type of care of written case scenarios with varying health problems and levels of urgency. To determine the adequacy of the assessments, a comparison with a reference standard was made. In addition, the association between background characteristics and triage organization and the adequacy of triage was examined. Setting Daytime general practices. Subjects Practice assistants. Main outcome measures Over- and under-estimation, sensitivity, specificity. Results The response rate was 41.1% (n = 973). The required care was assessed adequately in 63.6% of cases, was over-estimated in 19.3%, and under-estimated in 17.1%. The sensitivity of identifying patients with a highly urgent problem was 76.7% and the specificity was 94.0%. The adequacy of the assessments of the required care was higher for more experienced assistants and assistants with fixed daily work meetings with the GP. Triage training, use of a triage tool, and authorization of advice were not associated with adequacy of triage. Conclusion Triage by practice assistants in general practices is efficient (high specificity), but potentially unsafe in highly urgent cases (suboptimal sensitivity). It is important to train practice assistants in identifying highly urgent cases. Key pointsGeneral practices increasingly use telephone triage to manage patient flows, but little is known about the organization and adequacy of triage in daytime practices.Telephone triage by general practice assistants is

  19. Deeply Virtual Compton Scattering on nucleons and nuclei in generalized vector meson dominance model

    SciTech Connect

    Vadim Guzey; Klaus Goeke; Marat Siddikov

    2008-02-01

    We consider Deeply Virtual Compton Scattering (DVCS) on nucleons and nuclei in the framework of generalized vector meson dominance (GVMD) model. We demonstrate that the GVMD model provides a good description of the HERA data on the dependence of the proton DVCS cross section on $Q^2$, $W$ (at $Q^2=4$ GeV$^2$) and $t$. At $Q^2 = 8$ GeV$^2$, the soft $W$-behavior of the GVMD model somewhat underestimates the $W$-dependence of the DVCS cross section due to the hard contribution not present in the GVMD model. We estimate $1/Q^2$ power-suppressed corrections to the DVCS amplitude and the DVCS cross section and find them large. We also make predictions for the nuclear DVCS amplitude and cross section in the kinematics of the future Electron-Ion Collider. We predict significant nuclear shadowing, which matches well predictions of the leading-twist nuclear shadowing in DIS on nuclei.

  20. Conditioned Fear Acquisition and Generalization in Generalized Anxiety Disorder.

    PubMed

    Tinoco-González, Daniella; Fullana, Miquel Angel; Torrents-Rodas, David; Bonillo, Albert; Vervliet, Bram; Blasco, María Jesús; Farré, Magí; Torrubia, Rafael

    2015-09-01

    Abnormal fear conditioning processes (including fear acquisition and conditioned fear-generalization) have been implicated in the pathogenesis of anxiety disorders. Previous research has shown that individuals with panic disorder present enhanced conditioned fear-generalization in comparison to healthy controls. Enhanced conditioned fear-generalization could also characterize generalized anxiety disorder (GAD), but research so far is inconclusive. An important confounding factor in previous research is comorbidity. The present study examined conditioned fear-acquisition and fear-generalization in 28 patients with GAD and 30 healthy controls using a recently developed fear acquisition and generalization paradigm assessing fear-potentiated startle and online expectancies of the unconditioned stimulus. Analyses focused on GAD patients without comorbidity but included also patients with comorbid anxiety disorders. Patients and controls did not differ as regards fear acquisition. However, contrary to our hypothesis, both groups did not differ either in most indexes of conditioned fear-generalization. Moreover, dimensional measures of GAD symptoms were not correlated with conditioned fear-generalization indexes. Comorbidity did not have a significant impact on the results. Our data suggest that conditioned fear-generalization is not enhanced in GAD. Results are discussed with special attention to the possible effects of comorbidity on fear learning abnormalities. PMID:26459843

  1. Primary reasoning behind the double ITCZ phenomenon in a coupled ocean-atmosphere general circulation model

    NASA Astrophysics Data System (ADS)

    Li, Jianglong; Zhang, Xuehong; Yu, Yongqiang; Dai, Fushan

    2004-12-01

    This paper investigates the processes behind the double ITCZ phenomenon, a common problem in Coupled ocean-atmosphere General Circulation Models (CGCMs), using a CGCM—FGCM-0 (Flexible General Circulation Model, version 0). The double ITCZ mode develops rapidly during the first two years of the integration and becomes a perennial phenomenon afterwards in the model. By way of Singular Value Decomposition (SVD) for SST, sea surface pressure, and sea surface wind, some air-sea interactions are analyzed. These interactions prompt the anomalous signals that appear at the beginning of the coupling to develop rapidly. There are two possible reasons, proved by sensitivity experiments: (1) the overestimated east-west gradient of SST in the equatorial Pacific in the ocean spin-up process, and (2) the underestimated amount of low-level stratus over the Peruvian coast in CCM3 (the Community Climate Model, Version Three). The overestimated east-west gradient of SST brings the anomalous equatorial easterly. The anomalous easterly, affected by the Coriolis force in the Southern Hemisphere, turns into an anomalous westerly in a broad area south of the equator and is enhanced by atmospheric anomalous circulation due to the underestimated amount of low-level stratus over the Peruvian coast simulated by CCM3. The anomalous westerly leads to anomalous warm advection that makes the SST warm in the southeast Pacific. The double ITCZ phenomenon in the CGCM is a result of a series of nonlocal and nonlinear adjustment processes in the coupled system, which can be traced to the uncoupled models, oceanic component, and atmospheric component. The zonal gradient of the equatorial SST is too large in the ocean component and the amount of low-level stratus over the Peruvian coast is too low in the atmosphere component.

  2. The general NFP hospital model.

    PubMed

    Al-Amin, Mona

    2012-01-01

    Throughout the past 30 years, there has been a lot of controversy surrounding the proliferation of new forms of health care delivery organizations that challenge and compete with general NFP community hospitals. Traditionally, the health care system in the United States has been dominated by general NFP (NFP) voluntary hospitals. With the number of for-profit general hospitals, physician-owned specialty hospitals, and ambulatory surgical centers increasing, a question arises: “Why is the general NFP community hospital the dominant model?” In order to address this question, this paper reexamines the history of the hospital industry. By understanding how the “general NFP hospital” model emerged and dominated, we attempt to explain the current dominance of general NFP hospitals in the ever changing hospital industry in the United States. PMID:22324062

  3. [European general practice research agenda].

    PubMed

    Mäntyselkä, Pekka; Koskela, Tuomas

    2014-01-01

    The EGPRN (European General Practice Research Network) research agenda is a review compiling the strengths and areas of development of European general practice, based on a systematic literature survey and its versatile analysis. The research agenda is a framework paper sharpening the definition and functions of general practice as well as its significance for researchers and decisionmakers. The agenda is useful in structuring the research, evaluation of research needs, strengthening of infrastructure and strategic planning of new research. PMID:24961062

  4. 3. General view of site from Lawrence General Hospital parking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. General view of site from Lawrence General Hospital parking deck (former location of coating mill) showing north side of structures; view to southeast. - Champion-International Paper Company, West bank of Spicket River at Canal Street, Lawrence, Essex County, MA

  5. Generalized second law for cosmology

    NASA Astrophysics Data System (ADS)

    Bousso, Raphael; Engelhardt, Netta

    2016-01-01

    We conjecture a novel generalized second law that can be applied in cosmology, regardless of whether an event horizon is present: the generalized entropy increases monotonically outside of certain hypersurfaces we call past Q-screens. A past Q-screen is foliated by surfaces whose generalized entropy (sum of area and entanglement entropy) is stationary along one future null direction and increasing along the other. We prove that our generalized second law holds in spacetimes obeying the quantum focusing conjecture. An analogous law applies to future Q-screens, which appear inside evaporating black holes and in collapsing regions.

  6. General Practice in Northern Norway

    PubMed Central

    Black, D. P.

    1975-01-01

    A study was made of general practice in northern Norway where conditions are similar to parts of rural Canada. The Norwegian general practitioner has developed expertise in the preventive and psychosocial aspects of practice and the team concept is highly developed. Since the general practitioner is separated from the hospital, his facilities for procedures and diagnostic workups are primitive. Involvement of general practitioners in medical education is not yet well developed although all new graduates spend a compulsory period in rural practice. PMID:20469187

  7. Modelling of filariasis in East Java with Poisson regression and generalized Poisson regression models

    NASA Astrophysics Data System (ADS)

    Darnah

    2016-04-01

    Poisson regression has been used if the response variable is count data that based on the Poisson distribution. The Poisson distribution assumed equal dispersion. In fact, a situation where count data are over dispersion or under dispersion so that Poisson regression inappropriate because it may underestimate the standard errors and overstate the significance of the regression parameters, and consequently, giving misleading inference about the regression parameters. This paper suggests the generalized Poisson regression model to handling over dispersion and under dispersion on the Poisson regression model. The Poisson regression model and generalized Poisson regression model will be applied the number of filariasis cases in East Java. Based regression Poisson model the factors influence of filariasis are the percentage of families who don't behave clean and healthy living and the percentage of families who don't have a healthy house. The Poisson regression model occurs over dispersion so that we using generalized Poisson regression. The best generalized Poisson regression model showing the factor influence of filariasis is percentage of families who don't have healthy house. Interpretation of result the model is each additional 1 percentage of families who don't have healthy house will add 1 people filariasis patient.

  8. [May the general practitioner not be concerned about the alcohol consumption of his patients?].

    PubMed

    Cnockaert, P

    2002-09-01

    Based on a literature review, the author points out the importance, in adult general medicine practice, of the prevalences in different alcohol consumption levels, alcohol induced sicknesses and dependencies. The very large frequency of these problems in general practice, the somatic repercussions of an excessive consumption and the general practitioner's possibilities of action on preventive and curative levels lead the physician to make a research about the alcohol consumption level of all his patients, to write it down on the patients files, to give at least a pronounced advice and to carry out a follow-up. The actual commitment of general practitioners and their issues are tackled. French inquiries show that if intention of research on risk patients is very frequent (85% of the practitioners), this attitude is far from being systematic for a whole practice (research by less than 50% of the practitioners and inscription in a space for less than 30% of the patients files). This relative commitment seems to be induced (french and belgian inquiries) by an underestimation of the effect of the advice given to the patient, and by a discouragement feeling in front of the impression of low treatment efficiency as well as the relapses and the attitudes of that kind of patients. PMID:12422453

  9. Generally Covariant Hamiltonian Approach to the Generalized Harmonic Formulation of General Relativity

    NASA Astrophysics Data System (ADS)

    Cao, Meng

    The goal of this dissertation is to develop a generally covariant Hamiltonian approach to the generalized harmonic formulation of general relativity. As en route investigations, an important class of coordinate transformations in the context of the 3 + 1 decomposition, foliation preserving transformations, is defined; transformation rules of various 3 + 1 decomposition variables under this change of coordinates are investigated; the notion of covariant time derivative under foliation preserving transformations is defined; gauge conditions of various numerical relativity formulations are rewritten in generally covariant form. The Hamiltonian formulation of the generalized harmonic system is defined in the latter part of this dissertation. With the knowledge of covariant time derivative, the Hamiltonian formulation is extended to achieve general covariance. The Hamiltonian formulation is further proved to be symmetric hyperbolic.

  10. Integrability and generalized monodromy matrix

    SciTech Connect

    Lhallabi, T.; Moujib, A.

    2007-09-15

    We construct the generalized monodromy matrix M-circumflex({omega}) of two-dimensional string effective action by introducing the T-duality group properties. The integrability conditions with general solutions depending on spectral parameter are given. This construction is investigated for the exactly solvable Wess, Zumino, Novikov, and Witten model in pp-wave limit when B=0.

  11. Sampling Assumptions in Inductive Generalization

    ERIC Educational Resources Information Center

    Navarro, Daniel J.; Dry, Matthew J.; Lee, Michael D.

    2012-01-01

    Inductive generalization, where people go beyond the data provided, is a basic cognitive capability, and it underpins theoretical accounts of learning, categorization, and decision making. To complete the inductive leap needed for generalization, people must make a key "sampling" assumption about how the available data were generated. Previous…

  12. Using "Informances" in General Music

    ERIC Educational Resources Information Center

    Zaffini, Erin Dineen

    2015-01-01

    General music teachers might be faced with formal performance expectations placed on them by administrators. While performance expectations are common in performance-based ensembles, meeting these expectations can be cumbersome and daunting to those who serve in the realm of general music. Informances--informative presentations of student learning…

  13. Social Justice as General Education

    ERIC Educational Resources Information Center

    Russo, Richard A.

    2004-01-01

    This paper addresses the neglect of social justice a social change in the undergraduate general education curriculum at a community college. The intended audience of this paper is community college instructors with heavy teaching loads of mostly general education courses. Without pretending to be a rigorous analysis of theories of radical pedagogy…

  14. General Education: An Interdisciplinary Approach.

    ERIC Educational Resources Information Center

    Scott, Charles V.; Moore, Kenneth D.

    The University of Science and Arts of Oklahoma, an experimental college, has developed an innovative general education program. Teaching approaches and organizational structures of the program have been changed to accommodate the new curriculum. The general education core, called the Interdisciplinary Studies Sequence (IDS), includes courses in…

  15. General-Aviation Control Loader

    NASA Technical Reports Server (NTRS)

    Baltrus, Daniel W.; Albang, Leroy F.; Hallinger, John A.; Burge, W. Wayne

    1988-01-01

    Artificial-feel system designed for general-aviation flight simulators. New system developed to replace directly lateral and longitudinal controls in general-aviation cockpit for use in flight-simulation research. Using peaucellier's cell to convert linear motion to rotary motion, control-loading system provides realistic control-force feedback to cockpit wheel and column controls.

  16. 14 CFR Section 4 - General

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Balance Sheet Classifications Section 4 General (a) The balance sheet accounts are designed to show the financial condition of the air... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false General Section 4 Section 4 Aeronautics...

  17. 14 CFR Section 4 - General

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Balance Sheet Classifications Section 4 General (a) The balance sheet accounts are designed to show the financial condition of the air... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false General Section 4 Section 4 Aeronautics...

  18. Personality, Intelligence and General Knowledge

    ERIC Educational Resources Information Center

    Furnham, Adrian; Chamorro-Premuzic, Tomas

    2006-01-01

    Three studies, all on student populations, looked at the relationship between a recently psychometrised measure of General Knowledge [Irwing, P., Cammock, T., & Lynn, R. (2001). Some evidence for the existence of a general factor of semantic memory and its components. "Personality and Individual Differences," 30, 857-871], both long and short…

  19. Freshman General Studies Thematic. 1973-.

    ERIC Educational Resources Information Center

    California State Univ., Chico.

    The Freshman General Studies Thematic Program (GST) at California State University, Chico was established in 1973 to create a general education program for freshmen and to give faculty the opportunity to explore innovative teaching methods. What resulted was a 33-unit, year-long interdisciplinary course for 36 well-motivated, well-prepared…

  20. General practice in Croatia, Yugoslavia

    PubMed Central

    Skupnjak, B.; Novosel, M.

    1976-01-01

    The position and importance of general practice in the Yugoslavian Health Service is being reviewed in a study of the working conditions, the composition and relationship of the primary health care team, the workload, and the opinions of the patients in Croatia, Yugoslavia. We found that many practices had barely half the recommended equipment, that the average workload was 40 patients a day, and that many general practitioners expected others to improve their organisation rather than undertaking it themselves. Those general-practitioner teams which we rated highly were also the most popular with patients. The job satisfaction of nurses varied and was highest when the doctors in the team did not have a high need for status for themselves. We consider general practice to be of crucial importance in the total system of health care in our country and believe that general practitioners should have the same status as specialists. PMID:1003392

  1. Louisiana Title V General Permits

    SciTech Connect

    Boyer, B.E.; Neal, T.L.

    1995-12-31

    Title V of the Federal Clean Air Act Amendments of 1990 requires federal operating permits for all major sources of air pollution. In 1992, Title 40, Part 70 of the Code of Federal Regulations (40 CFR Part 70) codified the law s requirements. These federal regulations, entitled Operating Permit Program, define the minimum requirements for state administered operating permit programs. The intent of Title V is to put into one document all requirements of an operating permit. General Permits for oil and gas facilities may be preferred if the facility can comply with all permit requirements. If greater flexibility than allowed by the General Permit is required, then the facility should apply for an individual Title V permit. General Permits are designed to streamline the permitting process, shorten the time it takes to obtain approval for initial and modified permits. The advantages of the General Permit include reduced paperwork and greater consistency because the permits are standardized. There should be less uncertainty because permit requirements will be known at the time of application. Approval times for Initial and modified General Permits should be reduced. Lengthy public notice procedures (and possible hearings) will be required for only the initial approval of the General Permit and not for each applicant to the permit. A disadvantage of General Permits is reduced flexibility since the facility must comply with the requirements of a standardized permit.

  2. Shape Reconstruction from Generalized Projections

    NASA Astrophysics Data System (ADS)

    Viikinkoski, Matti

    2016-01-01

    In this thesis we develop methods for recovering the three-dimensional shape of an object from generalized projections. We particularly focus on the problems encountered when data are presented as discrete image fields. We demonstrate the usefulness of the Fourier transform in transferring the image data and shape model projections to a domain more suitable for gradient based optimization. To substantiate the general applicability of our methods to observational astronomy, we reconstruct shape models for several asteroids observed with adaptive optics, thermal infrared interferometry, or range-Doppler radar. The reconstructions are carried out with the ADAM software package that we have designed for general use.

  3. Computations of generalized Dolbeault cohomology

    SciTech Connect

    Cavalcanti, Gil R.

    2009-02-02

    We study the (generalized Dolbeault) cohomology of generalized complex manifolds in 4 real dimensions. We show that in 4 real dimensions, the first cohomology around a nondegenerate type change point is given by holomorphic (1,0) forms defined on the type change locus. We use this to compute the cohomology of a neighbourhood of a compact component of the type change locus as well as that of the blow-up of a type change point. Finally, we use these computations to determine the generalized cohomology of some concrete examples.

  4. Generalized Klein-Kramers equations

    NASA Astrophysics Data System (ADS)

    Fa, Kwok Sau

    2012-12-01

    A generalized Klein-Kramers equation for a particle interacting with an external field is proposed. The equation generalizes the fractional Klein-Kramers equation introduced by Barkai and Silbey [J. Phys. Chem. B 104, 3866 (2000), 10.1021/jp993491m]. Besides, the generalized Klein-Kramers equation can also recover the integro-differential Klein-Kramers equation for continuous-time random walk; this means that it can describe the subdiffusive and superdiffusive regimes in the long-time limit. Moreover, analytic solutions for first two moments both in velocity and displacement (for force-free case) are obtained, and their dynamic behaviors are investigated.

  5. Recent advances in general relativity

    SciTech Connect

    Janis, A.I.; Porter, J.R.

    1992-01-01

    The papers included in this book arose from a Discussion Conference on Recent Advances in General Relativity, which was held at the University of Pittsburgh, May 3-5, 1990, in honor of Ted Newman on the occasion of his 60th birthday. The book opens with a contribution outlining successes and problems of general relativity. Two contributions are devoted to quantum gravity. Discussions are included about general relativistic astrophysics, mathematics, and gravitational radiation. There are also workshop reports on classical gravity and quantum gravity.

  6. Alternative fuels for general aviation

    SciTech Connect

    Not Available

    1983-01-01

    The price and availability of fuel continues to be a major barrier to the free expansion of general aviation. Although this increase in fuel prices had a more severe impact on airlines, it has also slowed the demand for general aviation aircraft. With the sales of general aviation aircraft in a depressed state, the development of alternative fuels such as liquid methane, ethanol, methanol, and automobile gasoline can help spur the industry back to health. Recent flight tests of these alternative fuels are examined.

  7. General Aviation Task Force report

    NASA Technical Reports Server (NTRS)

    1993-01-01

    General aviation is officially defined as all aviation except scheduled airlines and the military. It is the only air transportation to many communities throughout the world. In order to reverse the recent decline in general aviation aircraft produced in the United States, the Task Force recommends that NASA provide the expertise and facilities such as wind tunnels and computer codes for aircraft design. General aviation manufacturers are receptive to NASA's innovations and technological leadership and are expected to be effective users of NASA-generated technologies.

  8. Anisotropic inflation with general potentials

    NASA Astrophysics Data System (ADS)

    Shi, JiaMing; Huang, XiaoTian; Qiu, TaoTao

    2016-04-01

    Anomalies in recent observational data indicate that there might be some "anisotropic hair" generated in an inflation period. To obtain general information about the effects of this anisotropic hair to inflation models, we studied anisotropic inflation models that involve one vector and one scalar using several types of potentials. We determined the general relationship between the degree of anisotropy and the fraction of the vector and scalar fields, and concluded that the anisotropies behave independently of the potentials. We also generalized our study to the case of multi-directional anisotropies.

  9. General relativity in Newtonian form

    NASA Astrophysics Data System (ADS)

    Gautreau, Ronald

    1990-06-01

    It is shown how the use of coordinates where time is measured with clocks moving radially in a spherically symmetric gravitational field leads to general relativistic dynamical expressions that are exactly identical to corresponding expressions in Newtonian theory. The general formalism is developed for the case where the stress-energy tensor is that of a perfect fluid. Expressions like the Newtonian inverse square gravitational law, the Newtonian equation of continuity for fluid flow, Newtonian conservation of energy, etc., follow quite naturally from the fully-fledged exact general relativistic equations. Specific examples involving cosmology and gravitational collapse are given.

  10. A generalized window energy rating system for typical office buildings

    SciTech Connect

    Tian, Cheng; Chen, Tingyao; Yang, Hongxing; Chung, Tse-ming

    2010-07-15

    Detailed computer simulation programs require lengthy inputs, and cannot directly provide an insight to relationship between the window energy performance and the key window design parameters. Hence, several window energy rating systems (WERS) for residential houses and small buildings have been developed in different countries. Many studies showed that utilization of daylight through elaborate design and operation of windows leads to significant energy savings in both cooling and lighting in office buildings. However, the current WERSs do not consider daylighting effect, while most of daylighting analyses do not take into account the influence of convective and infiltration heat gains. Therefore, a generalized WERS for typical office buildings has been presented, which takes all primary influence factors into account. The model includes embodied and operation energy uses and savings by a window to fully reflect interactions among the influence parameters. Reference locations selected for artificial lighting and glare control in the current common simulation practice may cause uncompromised conflicts, which could result in over- or under-estimated energy performance. Widely used computer programs, DOE2 and ADELINE, for hourly daylighting and cooling simulations have their own weaknesses, which may result in unrealistic or inaccurate results. An approach is also presented for taking the advantages of the both programs and avoiding their weaknesses. The model and approach have been applied to a typical office building of Hong Kong as an example to demonstrate how a WERS in a particular location can be established and how well the model can work. The energy effect of window properties, window-to-wall ratio (WWR), building orientation and lighting control strategies have been analyzed, and can be indicated by the localized WERS. An application example also demonstrates that the algebraic WERS derived from simulation results can be easily used for the optimal design of

  11. The Role of Spatial Disorientation in Fatal General Aviation Accidents

    NASA Technical Reports Server (NTRS)

    Scheuring, RIchard

    2005-01-01

    In-flight Spatial Disorientation (SD) in pilots is a serious threat to aviation safety. Indeed, SD may play a much larger role in aviation accidents than the approximate 6-8% reported by the National Transportation Safety Board (NTSB) each year, because some accidents coded by the NTSB as aircraft control-not maintained (ACNM) may actually result from SD. The purpose of this study is to determine whether SD is underestimated as a cause of fatal general aviation (GA) accidents in the NTSB database. Fatal GA airplane accidents occurring between January 1995 and December 1999 were reviewed from the NTSB aviation accident database. Cases coded as ACNM or SD as the probable cause were selected for review by a panel of aerospace medicine specialists. Using a rating scale, each rater was instructed to determine if SD was the probable cause of the accident. Agreement between the raters and agreement between the raters and the NTSB were evaluated by Kappa statistics. The raters agreed that 11 out of 20 (55%) accidents coded by the NTSB as ACNM were probably caused by SD (p less than 0.05). Agreement between the raters and the NTSB did not reach significance (p greater than 0.05). The 95% C.I. for the sampling population estimated that between 33-77% of cases that the NTSB identified as ACNM could be identified by aerospace medicine experts as SD. Aerospace medicine specialists agreed that some cases coded by the NTSB as ACNM were probably caused by SD. Consequently, a larger number of accidents may be caused by the pilot succumbing to SD than indicated in the NTSB database. This new information should encourage regulating agencies to insure that pilots receive SD recognition training, enabling them to take appropriate corrective actions during flight. This could lead to new training standards, ultimately saving lives among GA airplane pilots.

  12. General Information about Pancreatic Cancer

    MedlinePlus

    ... Research Pancreatic Cancer Treatment (PDQ®)–Patient Version General Information About Pancreatic Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  13. General Information about Vaginal Cancer

    MedlinePlus

    ... Research Vaginal Cancer Treatment (PDQ®)–Patient Version General Information About Vaginal Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  14. General Information about Gallbladder Cancer

    MedlinePlus

    ... Treatment Gallbladder Cancer Treatment (PDQ®)–Patient Version General Information About Gallbladder Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  15. General Information about Ewing Sarcoma

    MedlinePlus

    ... Research Ewing Sarcoma Treatment (PDQ®)–Patient Version General Information About Ewing Sarcoma Go to Health Professional Version ... the PDQ Pediatric Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  16. General Information about Laryngeal Cancer

    MedlinePlus

    ... Research Laryngeal Cancer Treatment (PDQ®)–Patient Version General Information About Laryngeal Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  17. General Information about Kaposi Sarcoma

    MedlinePlus

    ... Research Kaposi Sarcoma Treatment (PDQ®)–Patient Version General Information About Kaposi Sarcoma Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  18. General Information about Bladder Cancer

    MedlinePlus

    ... Research Bladder Cancer Treatment (PDQ®)–Patient Version General Information About Bladder Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  19. General Information About Endometrial Cancer

    MedlinePlus

    ... Research Endometrial Cancer Treatment (PDQ®)–Patient Version General Information About Endometrial Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  20. General Information about Childhood Astrocytomas

    MedlinePlus

    ... Research Childhood Astrocytomas Treatment (PDQ®)–Patient Version General Information About Childhood Astrocytomas Go to Health Professional Version ... the PDQ Pediatric Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  1. General Information about Vulvar Cancer

    MedlinePlus

    ... Research Vulvar Cancer Treatment (PDQ®)–Patient Version General Information About Vulvar Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  2. General Information about Childhood Ependymoma

    MedlinePlus

    ... Research Childhood Ependymoma Treatment (PDQ®)–Patient Version General Information About Childhood Ependymoma Go to Health Professional Version ... body and the age of the child. The information from tests and procedures done to detect (find) ...

  3. General Information about Thyroid Cancer

    MedlinePlus

    ... Research Thyroid Cancer Treatment (PDQ®)–Patient Version General Information About Thyroid Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  4. General Information about Gastric Cancer

    MedlinePlus

    ... Research Gastric Cancer Treatment (PDQ®)–Patient Version General Information About Gastric Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  5. General Information about Esophageal Cancer

    MedlinePlus

    ... Research Esophageal Cancer Treatment (PDQ®)–Patient Version General Information About Esophageal Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  6. General Information About Uterine Sarcoma

    MedlinePlus

    ... Research Uterine Sarcoma Treatment (PDQ®)–Patient Version General Information About Uterine Sarcoma Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  7. General Information about Rectal Cancer

    MedlinePlus

    ... Research Rectal Cancer Treatment (PDQ®)–Patient Version General Information About Rectal Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  8. General Information about Penile Cancer

    MedlinePlus

    ... Treatment Penile Cancer Treatment (PDQ®)–Patient Version General Information About Penile Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  9. General Information about Hypopharyngeal Cancer

    MedlinePlus

    ... Research Hypopharyngeal Cancer Treatment (PDQ®)–Patient Version General Information About Hypopharyngeal Cancer Go to Health Professional Version ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  10. On superpotentials in general relativity

    NASA Astrophysics Data System (ADS)

    Stolín, Oldřich; Novotný, Jan

    2001-10-01

    It is shown that the Einstein—Freud, Landau—Lifshitz and Møller tetrad super-potentials represent special cases of a more general construction. The tetrad version of the Landau—Lifshitz superpotential is derived.

  11. General Information about Breast Cancer

    MedlinePlus

    ... of Breast & Gynecologic Cancers Breast Cancer Screening Research Breast Cancer Treatment (PDQ®)–Patient Version General Information About Breast Cancer Go to Health Professional Version Key Points Breast ...

  12. A General Questionnaire Analysis Program

    ERIC Educational Resources Information Center

    Aiken, Lewis R.

    1978-01-01

    A general FORTRAN computer program for analyzing categorical or frequency data obtained from questionnaires is described. A variety of descriptive statistics, chi square, Kendall's tau and Cramer's statistic are provided. (Author/JKS)

  13. Generalized melting criterion for amorphization

    SciTech Connect

    Devanathan, R. |; Lam, N.Q.; Okamoto, P.R.; Meshii, M.

    1992-12-01

    We present a thermodynamic model of solid-state amorphization based on a generalization of the well-known Lindemann criterion. The original Lindemann criterion proposes that melting occurs when the root-mean-square amplitude of thermal displacement exceeds a critical value. This criterion can be generalized to include solid-state amorphization by taking into account the static displacements. In an effort to verify the generalized melting criterion, we have performed molecular dynamics simulations of radiation-induced amorphization in NiZr, NiZr{sub 2}, NiTi and FeTi using embedded-atom potentials. The average shear elastic constant G was calculated as a function of the total mean-square atomic displacement following random atom-exchanges and introduction of Frenkel pairs. Results provide strong support for the generalized melting criterion.

  14. On generalized distributions and pathways

    NASA Astrophysics Data System (ADS)

    Mathai, A. M.; Haubold, H. J.

    2008-03-01

    The scalar version of the pathway model of Mathai [A.M. Mathai, Linear Alg. Appl. 396 (2005) 317] is shown to be associated with a large number of probability models used in physics. Different families of densities are listed here, which are all connected through the pathway parameter α, generating a distributional pathway. The idea is to switch from one functional form to another through this parameter and it is shown that one can proceed from the generalized type-1 beta family to generalized type-2 beta family to generalized gamma family. It is also shown that the pathway model is available by maximizing a generalized measure of entropy, leading to an entropic pathway, covering the particularly interesting cases of Tsallis statistics [C. Tsallis, J. Stat. Phys. 52 (1988) 479] and superstatistics [C. Beck, E.G.D. Cohen, Physica A 322 (2003) 267].

  15. Generalized Teleportation and Entanglement Recycling

    NASA Astrophysics Data System (ADS)

    Strelchuk, Sergii; Horodecki, Michał; Oppenheim, Jonathan

    2013-01-01

    We introduce new teleportation protocols which are generalizations of the original teleportation protocols that use the Pauli group and the port-based teleportation protocols, introduced by Hiroshima and Ishizaka, that use the symmetric permutation group. We derive sufficient conditions for a set of operations, which in general need not form a group, to give rise to a teleportation protocol and provide examples of such schemes. This generalization leads to protocols with novel properties and is needed to push forward new schemes of computation based on them. Port-based teleportation protocols and our generalizations use a large resource state consisting of N singlets to teleport only a single qubit state reliably. We provide two distinct protocols which recycle the resource state to teleport multiple states with error linearly increasing with their number. The first protocol consists of sequentially teleporting qubit states, and the second teleports them in a bulk.

  16. Problem Solving with General Semantics.

    ERIC Educational Resources Information Center

    Hewson, David

    1996-01-01

    Discusses how to use general semantics formulations to improve problem solving at home or at work--methods come from the areas of artificial intelligence/computer science, engineering, operations research, and psychology. (PA)

  17. Generalized teleportation and entanglement recycling.

    PubMed

    Strelchuk, Sergii; Horodecki, Michał; Oppenheim, Jonathan

    2013-01-01

    We introduce new teleportation protocols which are generalizations of the original teleportation protocols that use the Pauli group and the port-based teleportation protocols, introduced by Hiroshima and Ishizaka, that use the symmetric permutation group. We derive sufficient conditions for a set of operations, which in general need not form a group, to give rise to a teleportation protocol and provide examples of such schemes. This generalization leads to protocols with novel properties and is needed to push forward new schemes of computation based on them. Port-based teleportation protocols and our generalizations use a large resource state consisting of N singlets to teleport only a single qubit state reliably. We provide two distinct protocols which recycle the resource state to teleport multiple states with error linearly increasing with their number. The first protocol consists of sequentially teleporting qubit states, and the second teleports them in a bulk. PMID:23383769

  18. A generalized gyrokinetic Poisson solver

    SciTech Connect

    Lin, Z.; Lee, W.W.

    1995-03-01

    A generalized gyrokinetic Poisson solver has been developed, which employs local operations in the configuration space to compute the polarization density response. The new technique is based on the actual physical process of gyrophase-averaging. It is useful for nonlocal simulations using general geometry equilibrium. Since it utilizes local operations rather than the global ones such as FFT, the new method is most amenable to massively parallel algorithms.

  19. Speed limits in general relativity

    NASA Astrophysics Data System (ADS)

    Low, Robert J.

    1999-02-01

    Some standard results on the initial value problem of general relativity in matter are reviewed. These results are applied first to show that in a well defined sense, finite perturbations in the gravitational field travel no faster than light, and second to show that it is impossible to construct a warp drive as considered by Alcubierre (1994 The warp drive: hyper-fast travel within general relativity Class. Quantum Grav. 11 L73-7) in the absence of exotic matter.

  20. Modeling Nucleon Generalized Parton Distributions

    SciTech Connect

    Radyushkin, Anatoly V.

    2013-05-01

    We discuss building models for nucleon generalized parton distributions (GPDs) H and E that are based on the formalism of double distributions (DDs). We find that the usual "DD+D-term'' construction should be amended by an extra term, generated by GPD E(x,\\xi). Unlike the $D$-term, this function has support in the whole -1 < x< 1 region, and in general does not vanish at the border points|x|=\\xi.

  1. A generalized nonlocal vector calculus

    NASA Astrophysics Data System (ADS)

    Alali, Bacim; Liu, Kuo; Gunzburger, Max

    2015-10-01

    A nonlocal vector calculus was introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) that has proved useful for the analysis of the peridynamics model of nonlocal mechanics and nonlocal diffusion models. A formulation is developed that provides a more general setting for the nonlocal vector calculus that is independent of particular nonlocal models. It is shown that general nonlocal calculus operators are integral operators with specific integral kernels. General nonlocal calculus properties are developed, including nonlocal integration by parts formula and Green's identities. The nonlocal vector calculus introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) is shown to be recoverable from the general formulation as a special example. This special nonlocal vector calculus is used to reformulate the peridynamics equation of motion in terms of the nonlocal gradient operator and its adjoint. A new example of nonlocal vector calculus operators is introduced, which shows the potential use of the general formulation for general nonlocal models.

  2. Future climate of the Caribbean from a super-high-resolution atmospheric general circulation model

    NASA Astrophysics Data System (ADS)

    Hall, Trevor C.; Sealy, Andrea M.; Stephenson, Tannecia S.; Kusunoki, Shoji; Taylor, Michael A.; Chen, A. Anthony; Kitoh, Akio

    2013-07-01

    Present-day (1979-2003) and future (2075-2099) simulations of mean and extreme rainfall and temperature are examined using data from the Meteorological Research Institute super-high-resolution atmospheric general circulation model. Analyses are performed over the 20-km model grid for (1) a main Caribbean basin, (2) sub-regional zones, and (3) specific Caribbean islands. Though the model's topography underestimates heights over the eastern Caribbean, it captures well the present-day spatial and temporal variations of seasonal and annual climates. Temperature underestimations range from 0.1 °C to 2 °C with respect to the Japanese Reanalysis and the Climatic Research Unit datasets. The model also captures fairly well sub-regional scale variations in the rainfall climatology. End-of-century projections under the Intergovernmental Panel on Climate Change SRES A1B scenario indicate declines in rainfall amounts by 10-20 % for most of the Caribbean during the early (May-July) and late (August-October) rainy seasons relative to the 1979-2003 baselines. The early dry season (November-January) is also projected to get wetter in the far north and south Caribbean by approximately 10 %. The model also projects a warming of 2-3 °C over the Caribbean region. Analysis of future climate extremes indicate a 5-10 % decrease in the simple daily precipitation intensity but no significant change in the number of consecutive dry days for Cuba, Jamaica, southern Bahamas, and Haiti. There is also indication that the number of hot days and nights will significantly increase over the main Caribbean basin.

  3. A confirmation of the general relativistic prediction of the Lense-Thirring effect.

    PubMed

    Ciufolini, I; Pavlis, E C

    2004-10-21

    An important early prediction of Einstein's general relativity was the advance of the perihelion of Mercury's orbit, whose measurement provided one of the classical tests of Einstein's theory. The advance of the orbital point-of-closest-approach also applies to a binary pulsar system and to an Earth-orbiting satellite. General relativity also predicts that the rotation of a body like Earth will drag the local inertial frames of reference around it, which will affect the orbit of a satellite. This Lense-Thirring effect has hitherto not been detected with high accuracy, but its detection with an error of about 1 per cent is the main goal of Gravity Probe B--an ongoing space mission using orbiting gyroscopes. Here we report a measurement of the Lense-Thirring effect on two Earth satellites: it is 99 +/- 5 per cent of the value predicted by general relativity; the uncertainty of this measurement includes all known random and systematic errors, but we allow for a total +/- 10 per cent uncertainty to include underestimated and unknown sources of error. PMID:15496915

  4. Derivation of the Generally Covariant Generalization of the Dirac Equation

    SciTech Connect

    Maker, David

    2010-09-30

    From the Occam's razor optimized assumption of a geometric point we derive a new generally covariant generalization of the Dirac equation. We solve that equation in domains r>r{sub H}, r{approx_equal}r{sub H}, and r

  5. Evaluation of the Catalytic Contribution from a Positioned General Base in Ketosteroid Isomerase.

    PubMed

    Lamba, Vandana; Yabukarski, Filip; Pinney, Margaux; Herschlag, Daniel

    2016-08-10

    Proton transfer reactions are ubiquitous in enzymes and utilize active site residues as general acids and bases. Crystal structures and site-directed mutagenesis are routinely used to identify these residues, but assessment of their catalytic contribution remains a major challenge. In principle, effective molarity measurements, in which exogenous acids/bases rescue the reaction in mutants lacking these residues, can estimate these catalytic contributions. However, these exogenous moieties can be restricted in reactivity by steric hindrance or enhanced by binding interactions with nearby residues, thereby resulting in over- or underestimation of the catalytic contribution, respectively. With these challenges in mind, we investigated the catalytic contribution of an aspartate general base in ketosteroid isomerase (KSI) by exogenous rescue. In addition to removing the general base, we systematically mutated nearby residues and probed each mutant with a series of carboxylate bases of similar pKa but varying size. Our results underscore the need for extensive and multifaceted variation to assess and minimize steric and positioning effects and determine effective molarities that estimate catalytic contributions. We obtained consensus effective molarities of ∼5 × 10(4) M for KSI from Comamonas testosteroni (tKSI) and ∼10(3) M for KSI from Pseudomonas putida (pKSI). An X-ray crystal structure of a tKSI general base mutant showed no additional structural rearrangements, and double mutant cycles revealed similar contributions from an oxyanion hole mutation in the wild-type and base-rescued reactions, providing no indication of mutational effects extending beyond the general base site. Thus, the high effective molarities suggest a large catalytic contribution associated with the general base. A significant portion of this effect presumably arises from positioning of the base, but its large magnitude suggests the involvement of additional catalytic mechanisms as well

  6. The Typical General Aviation Aircraft

    NASA Technical Reports Server (NTRS)

    Turnbull, Andrew

    1999-01-01

    The reliability of General Aviation aircraft is unknown. In order to "assist the development of future GA reliability and safety requirements", a reliability study needs to be performed. Before any studies on General Aviation aircraft reliability begins, a definition of a typical aircraft that encompasses most of the general aviation characteristics needs to be defined. In this report, not only is the typical general aviation aircraft defined for the purpose of the follow-on reliability study, but it is also separated, or "sifted" into several different categories where individual analysis can be performed on the reasonably independent systems. In this study, the typical General Aviation aircraft is a four-place, single engine piston, all aluminum fixed-wing certified aircraft with a fixed tricycle landing gear and a cable operated flight control system. The system breakdown of a GA aircraft "sifts" the aircraft systems and components into five categories: Powerplant, Airframe, Aircraft Control Systems, Cockpit Instrumentation Systems, and the Electrical Systems. This breakdown was performed along the lines of a failure of the system. Any component that caused a system to fail was considered a part of that system.

  7. Generalized bi-circular projections

    NASA Astrophysics Data System (ADS)

    Lin, Pei-Kee

    2008-04-01

    Recall that a projection P on a complex Banach space X is a generalized bi-circular projection if P+[lambda](I-P) is a (surjective) isometry for some [lambda] such that [lambda]=1 and [lambda][not equal to]1. It is easy to see that every hermitian projection is generalized bi-circular. A generalized bi-circular projection is said to be nontrivial if it is not hermitian. Botelho and Jamison showed that a projection P on C([0,1]) is a nontrivial generalized bi-circular projection if and only if P-(I-P) is a surjective isometry. In this article, we prove that if P is a projection such that P+[lambda](I-P) is a (surjective) isometry for some [lambda], then either P is hermitian or [lambda] is an nth unit root of unity. We also show that for any nth unit root [lambda] of unity, there are a complex Banach space X and a nontrivial generalized bi-circular projection P on X such that P+[lambda](I-P) is an isometry.

  8. SOFIA general investigator science program

    NASA Astrophysics Data System (ADS)

    Young, Erick T.; Andersson, B.-G.; Becklin, Eric E.; Reach, William T.; Sankrit, Ravi; Zinnecker, Hans; Krabbe, Alfred

    2014-07-01

    SOFIA is a joint project between NASA and DLR, the German Aerospace Center, to provide the worldwide astronomical community with an observatory that offers unique capabilities from visible to far-infrared wavelengths. SOFIA consists of a 2.7-m telescope mounted in a highly modified Boeing 747-SP aircraft, a suite of instruments, and the scientific and operational infrastructure to support the observing program. This paper describes the current status of the observatory and details the General Investigator program. The observatory has recently completed major development activities, and it has transitioned into full operational status. Under the General Investigator program, astronomers submit proposals that are peer reviewed for observation on the facility. We describe the results from the first two cycles of the General Investigator program. We also describe some of the new observational capabilities that will be available for Cycle 3, which will begin in 2015.

  9. New roles for general practitioners.

    PubMed Central

    Handysides, S.

    1994-01-01

    General practice is likely to change greatly over the next few years. Increases in care in the community and day surgery will lead to more work, and the demand for better data on practice activity will mean the development of audit and epidemiological work. To make time general practitioners will have to learn to delegate work that does not require a doctor. Fundholding has already stimulated some practices to bring services to patients rather than send patients to hospital, and this trend seems set to continue. It is important to pool resources, not only within practices but among other practices in the area--joint action will increase the ability to improve the services for patients. If general practitioners take the opportunity to gain control of the changes the morale of the profession should improve. Images p513-a p514-a PMID:8136671

  10. Generalization of the Euler Angles

    NASA Technical Reports Server (NTRS)

    Bauer, Frank H. (Technical Monitor); Shuster, Malcolm D.; Markley, F. Landis

    2002-01-01

    It is shown that the Euler angles can be generalized to axes other than members of an orthonormal triad. As first shown by Davenport, the three generalized Euler axes, hereafter: Davenport axes, must still satisfy the constraint that the first two and the last two axes be mutually perpendicular if these axes are to define a universal set of attitude parameters. Expressions are given which relate the generalized Euler angles, hereafter: Davenport angles, to the 3-1-3 Euler angles of an associated direction-cosine matrix. The computation of the Davenport angles from the attitude matrix and their kinematic equation are presented. The present work offers a more direct development of the Davenport angles than Davenport's original publication and offers additional results.

  11. Generalized pruritus preceding paraneoplastic neuropathy.

    PubMed

    Hébant, Benjamin; Miret, Nicolas; Berthelot, Lucile; Jaafar, Mohamad; Maltête, David; Lefaucheur, Romain

    2016-04-01

    Paraneoplastic syndromes are a group of rare disorders involving non-metastatic systemic effects accompanying malignancies, and occur remotely from the tumor itself. Chronic pruritus lasting more than 6 weeks can be from paraneoplastic origin. A 65-year-old woman was admitted for generalized pruritus lasting for 1 month, despite treatment with prednisolone, levocetirizine and hydroxyzine. General examination was normal. Biological data and gastroscopy were normal. One month later, the patient was readmitted for worsening of her pruritus and walking impairment, revealing a severe sensory neuropathy. Blood anti-Hu antibodies returned positive at a level of 400 (normal <100). Bronchoscopy and bronchial biopsies revealed small-cell lung carcinoma. To our knowledge, the association of generalized pruritus and paraneoplastic neuropathy has been rarely reported. Our observation raises the question of a pathophysiological continuum between pruritus and neuropathy in a paraneoplastic context. PMID:26633089

  12. Generalized expression for polarization density

    SciTech Connect

    Wang Lu; Hahm, T. S.

    2009-06-15

    A general polarization density which consists of classical and neoclassical parts is systematically derived via modern gyrokinetics and bounce kinetics by employing a phase-space Lagrangian Lie-transform perturbation method. The origins of polarization density are further elucidated. Extending the work on neoclassical polarization for long wavelength compared to ion banana width [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)], an analytical formula for the generalized neoclassical polarization including both finite-banana-width and finite-Larmor-radius effects for arbitrary radial wavelength in comparison to banana width and gyroradius is derived. In additional to the contribution from trapped particles, the contribution of passing particles to the neoclassical polarization is also explicitly calculated. The generalized analytic expression agrees very well with the previous numerical results for a wide range of radial wavelength.

  13. A general approach to bosonization

    NASA Astrophysics Data System (ADS)

    Setlur, Girish S.; Meera, V.

    2007-10-01

    We summarize recent developments in the field of higher dimensional bosonization made by Setlur and collaborators and propose a general formula for the field operator in terms of currents and densities in one dimension using a new ingredient known as a `singular complex number'. Using this formalism, we compute the Green function of the homogeneous electron gas in one spatial dimension with short-range interaction leading to the Luttinger liquid and also with long-range interactions that lead to a Wigner crystal whose momentum distribution computed recently exhibits essential singularities. We generalize the formalism to finite temperature by combining with the author's hydrodynamic approach. The one-particle Green function of this system with essential singularities cannot be easily computed using the traditional approach to bosonization which involves the introduction of momentum cutoffs, hence the more general approach of the present formalism is proposed as a suitable alternative.

  14. Generalized Edgeworth-Pareto principle

    NASA Astrophysics Data System (ADS)

    Noghin, V. D.

    2015-12-01

    The general multicriteria choice problem with m individual preference relations and an asymmetric collective preference relation is considered. The concept of a k-effective alternative is introduced, which coincides with an effective alternative for k = 1 and represents a weakly effective alternative for k = m. For the other integer values of k, it lies somewhere in between. In terms of the general multicriteria choice problem, the Pareto axiom and the exclusion axiom for dominated alternatives are stated. Assuming that these axioms hold, a generalized Edgeworth-Pareto principle is established, which was earlier introduced by the author in the special case k = 1. The results are extended to a fuzzy collective preference relation and to a fuzzy set of initial alternatives.

  15. Determination of ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in NORM products from oil and gas exploration: problems in activity underestimation due to the presence of metals and self-absorption of photons.

    PubMed

    Landsberger, S; Brabec, C; Canion, B; Hashem, J; Lu, C; Millsap, D; George, G

    2013-11-01

    Typical calibration of solid environmental samples for the determination of (226)Ra, (228)Ra and (210)Pb entails the use of standard reference materials which have a very similar matrix. However, TENORM samples from the oil and gas exploration contain unusually high amounts of calcium, strontium and barium which can severely attenuate the photons of (210)Pb and (226)Ra with their characteristic 46.1 keV and 186.2 keV gamma-rays, respectively and to some extent (228)Ra with the characteristic gamma-rays of 911.2 keV and 969.0 keV. We used neutron activation analysis to evaluate the content of TENORM for calcium, barium and strontium and then used a software program SELABS to determine the self-absorption. Our results confirm that even in Petrie containers with small dimensions the (210)Pb can be underestimated by almost by a factor of four while (226)Ra can be underestimated by 5%. The (228)Ra activities are virtually unaffected due to the higher energy gamma-rays. However, the implications for TENORM studies that employ large Marinelli containers having sample sizes between 0.25 and 1.0 L may be severely compromised by the presence of high Z elements in elevated concentrations. The usual spectral interferences on (226)Ra, (228)Ra and (210)Pb coming from other radionuclides in the (234)U, (235)U and (238)U decay chains are virtually nonexistent due the very high activity levels of (226)Ra, (228)Ra and (210)Pb in the tens of thousands of Bq/kg. PMID:23514714

  16. The MRI-measured arterial input function resulting from a bolus injection of Gd-DTPA in a rat model of stroke slightly underestimates that of Gd-[14C]DTPA and marginally overestimates the blood-to-brain influx rate constant determined by Patlak plots.

    PubMed

    Nagaraja, Tavarekere N; Karki, Kishor; Ewing, James R; Divine, George W; Fenstermacher, Joseph D; Patlak, Clifford S; Knight, Robert A

    2010-06-01

    The hypothesis that the arterial input function (AIF) of gadolinium-diethylenetriaminepentaacetic acid injected by intravenous bolus and measured by the change in the T(1)-relaxation rate (Delta R(1); R(1) = 1/T(1)) of superior sagittal sinus blood (AIF-I) approximates the AIF of (14)C-labeled gadolinium-diethylenetriaminepentaacetic acid measured in arterial blood (reference AIF) was tested in a rat stroke model (n = 13). Contrary to the hypothesis, the initial part of the Delta R(1)-time curve was underestimated, and the area under the normalized curve for AIF-I was about 15% lower than that for the reference AIF. Hypothetical AIFs for gadolinium-diethylenetriaminepentaacetic acid were derived from the reference AIF values and averaged to obtain a cohort-averaged AIF. Influx rate constants (K(i)) and proton distribution volumes at zero time (V(p) + V(o)) were estimated with Patlak plots of AIF-I, hypothetical AIFs, and cohort-averaged AIFs and tissue Delta R(1) data. For the regions of interest, the K(i)s estimated with AIF-I were slightly but not significantly higher than those obtained with hypothetical AIFs and cohort-averaged AIF. In contrast, V(p) + V(o) was significantly higher when calculated with AIF-I. Similar estimates of K(i) and V(p) + V(o) were obtained with hypothetical AIFs and cohort-averaged AIF. In summary, AIF-I underestimated the reference AIF; this shortcoming had little effect on the K(i) calculated by Patlak plot but produced a significant overestimation of V(p) + V(o). PMID:20512853

  17. Fourth order deformed general relativity

    NASA Astrophysics Data System (ADS)

    Cuttell, Peter D.; Sakellariadou, Mairi

    2014-11-01

    Whenever the condition of anomaly freedom is imposed within the framework of effective approaches to loop quantum cosmology, one seems to conclude that a deformation of general covariance is required. Here, starting from a general deformation we regain an effective gravitational Lagrangian including terms up to fourth order in extrinsic curvature. We subsequently constrain the form of the corrections for the homogeneous case, and then investigate the conditions for the occurrence of a big bounce and the realization of an inflationary era, in the presence of a perfect fluid or scalar field.

  18. General aviation IFR operational problems

    NASA Technical Reports Server (NTRS)

    Bolz, E. H.; Eisele, J. E.

    1979-01-01

    Operational problems of general aviation IFR operators (particularly single pilot operators) were studied. Several statistical bases were assembled and utilized to identify the more serious problems and to demonstrate their magnitude. These bases include official activity projections, historical accident data and delay data, among others. The GA operating environment and cockpit environment were analyzed in detail. Solutions proposed for each of the problem areas identified are based on direct consideration of currently planned enhancements to the ATC system, and on a realistic assessment of the present and future limitations of general aviation avionics. A coordinated set of research program is suggested which would provide the developments necessary to implement the proposed solutions.

  19. Quasilocal Hamiltonians in general relativity

    SciTech Connect

    Anderson, Michael T.

    2010-10-15

    We analyze the definition of quasilocal energy in general relativity based on a Hamiltonian analysis of the Einstein-Hilbert action initiated by Brown-York. The role of the constraint equations, in particular, the Hamiltonian constraint on the timelike boundary, neglected in previous studies, is emphasized here. We argue that a consistent definition of quasilocal energy in general relativity requires, at a minimum, a framework based on the (currently unknown) geometric well-posedness of the initial boundary value problem for the Einstein equations.

  20. Spinning fluids in general relativity

    NASA Technical Reports Server (NTRS)

    Ray, J. R.; Smalley, L. L.

    1982-01-01

    General relativity field equations are employed to examine a continuous medium with internal spin. A variational principle formerly applied in the special relativity case is extended to the general relativity case, using a tetrad to express the spin density and the four-velocity of the fluid. An energy-momentum tensor is subsequently defined for a spinning fluid. The equations of motion of the fluid are suggested to be useful in analytical studies of galaxies, for anisotropic Bianchi universes, and for turbulent eddies.