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1

Lung Ventilation/Perfusion Scan  

MedlinePLUS

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

2

Measurement of continuous distributions of ventilation-perfusion ratios - Theory  

NASA Technical Reports Server (NTRS)

The resolution of the technique considered is sufficient to describe smooth distributions containing blood flow to unventilated regions (shunt), ventilation to unperfused regions (dead space), and up to three additional modes over the range of finite ventilation-perfusion ratios. In particular, areas whose ventilation-perfusion ratios are low can be separated from unventilated regions and those whose ventilation-perfusion ratios are high can similarly be distinguished from unperfused areas.

Wagner, P. D.; Saltzman, H. A.; West, J. B.

1974-01-01

3

Imbalances in Regional Lung Ventilation A Validation Study on Electrical Impedance Tomography  

Microsoft Academic Search

Imbalances in regional lung ventilation, with gravity-dependent collapse and overdistention of nondependent zones, are likely asso- ciated to ventilator-induced lung injury. Electric impedance tomog- raphy is a new imaging technique that is potentially capable of monitoring those imbalances. The aim of this study was to validate electrical impedance tomography measurements of ventilation dis- tribution, by comparison with dynamic computerized tomography

Joao B. Borges; Valdelis N. Okamoto; Gustavo F. J. Matos; Mauro R. Tucci; Maria P. R. Caramez; Harki Tanaka; Fernando Suarez Sipmann; Durval C. B. Santos; Carmen S. V. Barbas; Carlos R. R. Carvalho; Marcelo B. P. Amato

4

Ventilation-perfusion matching during exercise  

NASA Technical Reports Server (NTRS)

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

Wagner, P. D.

1992-01-01

5

Mediastinal sarcoidosis presenting as ventilation-perfusion mismatch.  

PubMed

Sarcoidosis is a disease of unknown etiology which is characterized pathologically by widespread noncaseating granulomas involving multiple organ systems. We report a case of sarcoidosis presenting as a ventilation-perfusion mismatch on a lung scan. PMID:8181357

Cohen, L A; Murphy, W D; Kelling, J S

1994-05-01

6

Inert gas analysis of ventilation-perfusion matching during hemodialysis.  

PubMed Central

The mechanism of hypoxemia during hemodialysis was investigated by the multiple inert gas elimination technique in anesthetized, paralyzed, mechanically ventilated dogs. Profound leukopenia occurred in the first hour of a 2-h hemodialysis with a cuprophan membrane and dialysate that contained acetate. Arterial partial pressure of O2 and CO2 and oxygen consumption remained unchanged during dialysis. Pulmonary carbon dioxide elimination and lung respiratory exchange ratio decreased with the initiation of dialysis, remained depressed throughout the duration of dialysis, and returned to predialysis levels after the cessation of dialysis. Cardiac output diminished during dialysis but did not return to base-line levels after dialysis. Multiple indices calculated from inert gas analysis revealed no ventilation-perfusion mismatching during dialysis. The shunt and perfusion to regions of low alveolar ventilation-to-perfusion ratio (VA/Q) were unchanged during dialysis. There was no change in the mean or standard deviation of the profile of the percentage of total perfusion to regions of the lung that had VA/Q near 1.0; nor was there any increase in the directly calculated arterial-alveolar partial pressure differences for the inert gases during dialysis. Dead space became mildly elevated during dialysis. These results show that during dialysis with controlled ventilation there is no ventilation-perfusion mismatching that leads to hypoxemia. During spontaneous ventilation any hypoxemia must occur due to hypoventilation secondary to the CO2 exchange by the dialyzer and subsequent reduction in pulmonary CO2 exchange. PMID:6715542

Ralph, D D; Ott, S M; Sherrard, D J; Hlastala, M P

1984-01-01

7

Combined MR Proton Lung Perfusion/Angiography and Helium Ventilation  

PubMed Central

Three-dimensional (3D) perfusion imaging allows the assessment of pulmonary blood flow in parenchyma and main pulmonary arteries simultaneously. MRI using laser-polarized 3He gas clearly shows the ventilation distribution with high signal-to-noise ratio (SNR). In this report, the feasibility of combined lung MR angiography, perfusion, and ventilation imaging is demonstrated in a porcine model. Ultrafast gradient-echo sequences have been used for 3D perfusion and angiographic imaging, in conjunction with the use of contrast agent injections. 2D multiple-section 3He imaging was performed subsequently by inhalation of 450 ml of hyperpolarized 3He gas. The MR techniques were examined in a series of porcine models with externally delivered pulmonary emboli and/or airway occlusions. With emboli, perfusion deficits without ventilation defects were observed; airway occlusion resulted in matched deficits in perfusion and ventilation. High-resolution MR angiography can unambiguously reveal the location and size of the blood emboli. The combination of the three imaging methods may provide complementary information on abnormal lung anatomy and function. PMID:11870828

Zheng, Jie; Leawoods, Jason C.; Nolte, Mark; Yablonskiy, Dmitriy A.; Woodard, Pamela K.; Laub, Gerhardt; Gropler, Robert J.; Conradi, Mark S.

2007-01-01

8

Teaching Ventilation/Perfusion Relationships in the Lung  

ERIC Educational Resources Information Center

This brief review is meant to serve as a refresher for faculty teaching respiratory physiology to medical students. The concepts of ventilation and perfusion matching are some of the most challenging ideas to learn and teach. Some strategies to consider in teaching these concepts are, first, to build from simple to more complex by starting with a…

Glenny, Robb W.

2008-01-01

9

Heterogeneity and Matching of Ventilation and Perfusion within Anatomical Lung Units in Rats  

PubMed Central

Prior studies exploring the spatial distributions of ventilation and perfusion have partitioned the lung into discrete regions not constrained by anatomical boundaries and may blur regional differences in perfusion and ventilation. To characterize the anatomical heterogeneity of regional ventilation and perfusion, we administered fluorescent microspheres to mark regional ventilation and perfusion in 5 Sprague-Dawley rats and then using highly automated computer algorithms, partitioned the lungs into regions defined by anatomical structures identified in the images. The anatomical regions ranged in size from the nearacinar to the lobar level. Ventilation and perfusion were well correlated at the smallest anatomical level. Perfusion and ventilation heterogeneity were relatively less in rats compared to data previously published in larger animals. The more uniform distributions may be due to a smaller gravitational gradient and/or the fewer number of generations in the distribution trees before reaching the level of gas exchange, making regional matching of ventilation and perfusion less extensive in small animals. PMID:23942308

Glenny, Robb W.; Bauer, Christian; Hofmanninger, Johannes; Lamm, Wayne J.; Krueger, Melissa A.; Beichel, Reinhard R.

2013-01-01

10

Lobe-based Estimating Ventilation and Perfusion from 3D CT scans of the Lungs  

E-print Network

Lobe-based Estimating Ventilation and Perfusion from 3D CT scans of the Lungs Travis McPhail Joe are the ventilation (air flow) and perfusion (blood flow) in the patient's lungs. Given the flow of air and blood as possible. The current state of the art technology for assessing the ventilation in a patient's lungs

Warren, Joe

11

Ventilation-perfusion matching in long-term microgravity  

NASA Technical Reports Server (NTRS)

We studied the ventilation-perfusion matching pattern in normal gravity (1 G) and short- and long-duration microgravity (microG) using the cardiogenic oscillations in the sulfur hexaflouride (SF(6)) and CO(2) concentration signals during the phase III portion of vital capacity single-breath washout experiments. The signal power of the cardiogenic concentration variations was assessed by spectral analysis, and the phase angle between the oscillations of the two simultaneously expired gases was obtained through cross-correlation. For CO(2), a significant reduction of cardiogenic power was observed in microG, with respect to 1 G, but the reduction was smaller and more variable in the case of SF(6). A shift from an in-phase condition in 1 G to an out-of-phase condition was found for both short- and long-duration microG. We conclude that, although the distribution of ventilation and perfusion becomes more homogeneous in microG, significant inhomogeneities persist and that areas of high perfusion become associated with areas of relatively lower ventilation. In addition, these modifications seem to remain constant during long-term exposure to microG.

Verbandt, Y.; Wantier, M.; Prisk, G. K.; Paiva, M.; West, J. B. (Principal Investigator)

2000-01-01

12

Gas exchange and ventilation-perfusion relationships in the lung.  

PubMed

This review provides an overview of the relationship between ventilation/perfusion ratios and gas exchange in the lung, emphasising basic concepts and relating them to clinical scenarios. For each gas exchanging unit, the alveolar and effluent blood partial pressures of oxygen and carbon dioxide (PO2 and PCO2) are determined by the ratio of alveolar ventilation to blood flow (V'A/Q') for each unit. Shunt and low V'A/Q' regions are two examples of V'A/Q' mismatch and are the most frequent causes of hypoxaemia. Diffusion limitation, hypoventilation and low inspired PO2 cause hypoxaemia, even in the absence of V'A/Q' mismatch. In contrast to other causes, hypoxaemia due to shunt responds poorly to supplemental oxygen. Gas exchanging units with little or no blood flow (high V'A/Q' regions) result in alveolar dead space and increased wasted ventilation, i.e. less efficient carbon dioxide removal. Because of the respiratory drive to maintain a normal arterial PCO2, the most frequent result of wasted ventilation is increased minute ventilation and work of breathing, not hypercapnia. Calculations of alveolar-arterial oxygen tension difference, venous admixture and wasted ventilation provide quantitative estimates of the effect of V'A/Q' mismatch on gas exchange. The types of V'A/Q' mismatch causing impaired gas exchange vary characteristically with different lung diseases. PMID:25063240

Petersson, Johan; Glenny, Robb W

2014-10-01

13

Regional ventilation/perfusion mismatch pattern in patient with Swyer James (MacLeod's) syndrome  

PubMed Central

Swyer James (McLeod's) syndrome (SJMS) is an uncommon disease, which occurs as a result of childhood bronchiolitis obliterans. Patients may not be diagnosed until later in their life. A 46-year-old man underwent ventilation/perfusion scintigraphy for acute onset of dyspnea. The scan showed markedly diminished ventilation and perfusion unilaterally on the right middle and inferior lobes. However, mismatched ventilation-perfusion pattern was shown on the upper right lobe, which was consistent with pulmonary embolism. Unilaterally matched ventilation/perfusion defect can see in SJMS in lung scintigraphy; however, when pulmoner embolism may accompany, scintigraphy should be carefully examined.

Sager, Sait; Asa, Sertac; Akyel, Re?it; Atahan, Ersan; Kanmaz, Bedii

2014-01-01

14

Ventilation/perfusion mismatch during lung aeration at birth.  

PubMed

At birth, the transition to newborn life is triggered by lung aeration, which stimulates a large increase in pulmonary blood flow (PBF). Current theories predict that the increase in PBF is spatially related to ventilated lung regions as they aerate after birth. Using simultaneous phase-contrast X-ray imaging and angiography we investigated the spatial relationships between lung aeration and the increase in PBF after birth. Six near-term (30-day gestation) rabbits were delivered by caesarean section, intubated and an intravenous catheter inserted, before they were positioned for X-ray imaging. During imaging, iodine was injected before ventilation onset, after ventilation of the right lung only, and after ventilation of both lungs. Unilateral ventilation increased iodine levels entering both left and right pulmonary arteries (PAs) and significantly increased heart rate, iodine ejection per beat, diameters of both left and right PAs, and number of visible vessels in both lungs. Within the 6th intercostal space, the mean gray level (relative measure of iodine level) increased from 68.3 ± 11.6 and 70.3 ± 7.5%·s to 136.3 ± 22.6 and 136.3 ± 23.7%·s in the left and right PAs, respectively. No differences were observed between vessels in the left and right lungs, despite the left lung not initially being ventilated. The increase in PBF at birth is not spatially related to lung aeration allowing a large ventilation/perfusion mismatch, or pulmonary shunting, to occur in the partially aerated lung at birth. PMID:24994883

Lang, Justin A R; Pearson, James T; te Pas, Arjan B; Wallace, Megan J; Siew, Melissa L; Kitchen, Marcus J; Fouras, Andreas; Lewis, Robert A; Wheeler, Kevin I; Polglase, Graeme R; Shirai, Mikiyasu; Sonobe, Takashi; Hooper, Stuart B

2014-09-01

15

EANM guidelines for ventilation/perfusion scintigraphy : Part 1. Pulmonary imaging with ventilation/perfusion single photon emission tomography.  

PubMed

Pulmonary embolism (PE) can only be diagnosed with imaging techniques, which in practice is performed using ventilation/perfusion scintigraphy (V/P(SCAN)) or multidetector computed tomography of the pulmonary arteries (MDCT). The epidemiology, natural history, pathophysiology and clinical presentation of PE are briefly reviewed. The primary objective of Part 1 of the Task Group's report was to develop a methodological approach to and interpretation criteria for PE. The basic principle for the diagnosis of PE based upon V/P(SCAN) is to recognize lung segments or subsegments without perfusion but preserved ventilation, i.e. mismatch. Ventilation studies are in general performed after inhalation of Krypton or technetium-labelled aerosol of diethylene triamine pentaacetic acid (DTPA) or Technegas. Perfusion studies are performed after intravenous injection of macroaggregated human albumin. Radiation exposure using documented isotope doses is 1.2-2 mSv. Planar and tomographic techniques (V/P(PLANAR) and V/P(SPECT)) are analysed. V/P(SPECT) has higher sensitivity and specificity than V/P(PLANAR). The interpretation of either V/P(PLANAR) or V/P(SPECT) should follow holistic principles rather than obsolete probabilistic rules. PE should be reported when mismatch of more than one subsegment is found. For the diagnosis of chronic PE, V/P(SCAN) is of value. The additional diagnostic yield from V/P(SCAN) includes chronic obstructive lung disease (COPD), heart failure and pneumonia. Pitfalls in V/P(SCAN) interpretation are considered. V/P(SPECT) is strongly preferred to V/P(PLANAR) as the former permits the accurate diagnosis of PE even in the presence of comorbid diseases such as COPD and pneumonia. Technegas is preferred to DTPA in patients with COPD. PMID:19562336

Bajc, M; Neilly, J B; Miniati, M; Schuemichen, C; Meignan, M; Jonson, B

2009-08-01

16

Idiopathic pulmonary fibrosis. A rare cause of scintigraphic ventilation-perfusion mismatch  

SciTech Connect

A case of idiopathic pulmonary fibrosis with multiple areas of mismatch on ventilation-perfusion lung imaging in the absence of pulmonary embolism is presented. Idiopathic pulmonary fibrosis is one of the few nonembolic diseases producing a pulmonary ventilation-perfusion mismatch. In this condition, chest radiographs may not detect the full extent of disease, and xenon-133 ventilation imaging may be relatively insensitive to morbid changes in small airways. Thus, when examining patients with idiopathic pulmonary fibrosis, one should be aware that abnormal perfusion imaging patterns without matching ventilation abnormalities are not always due to embolism. In this setting, contrast pulmonary angiography is often needed for accurate differential diagnosis.

Pochis, W.T.; Krasnow, A.Z.; Collier, B.D.; Mewissen, M.W.; Almagro, U.A.; Hellman, R.S.; Isitman, A.T. (Medical College of Wisconsin, Milwaukee (USA))

1990-05-01

17

Quantitative ventilation-perfusion lung scans in infants and children: utility of a submicronic radiolabeled aerosol to assess ventilation  

Microsoft Academic Search

The quantitative assessment of regional pulmonary ventilation and perfusion provides useful information regarding lung function. Its use in infants and young children, however, has been minimal because of practical and technical limitations when the distribution of ventilation is assessed by radioactive gases. In 16 infants and children we used an inexpensive commercially available nebulizer to produce a submicronic aerosol labeled

H. M. OBrodovich; G. Coates

1984-01-01

18

Teaching ventilation/perfusion relationships in the lung  

NSDL National Science Digital Library

This brief review is meant to serve as a refresher for faculty teaching respiratory physiology to medical students. The concepts of ventilation and perfusion matching are some of the most challenging ideas to learn and teach. Some strategies to consider in teaching these concepts are, first, to build from simple to more complex by starting with a single lung unit and then adding additional units representing shunting, mismatch, and deadspace. Second, use simplified analogies, such as a bathtub, to help students conceptualize new ideas. Third, introduce the concept of alveolar to arterial O2 differences and the mechanisms for increasing differences as additional lung units are added. Fourth, use the consistent thread of causes of hypoxemia through the lecture to maintain continuity and provide clinical relevance. Finally, use clinically relevant examples at each step and solidify new concepts by discussing differential diagnoses at the end of the lecture(s).

Robb W Glenny (University of Washington Medicine and Physiology and Biophysics)

2008-07-09

19

Ventilation-perfusion inequality in chronic obstructive pulmonary disease.  

PubMed Central

A multiple inert gas elimination method was used to study the mechanism of impaired gas exchange in 23 patients with advanced chronic obstructive pulmonary disease (COPD). Three patterns of ventilation-perfusion (Va/Q) inequality were found: (a) A pattern with considerable regions of high (greater than 3) VA/Q, none of low (less than 0.1) VA/Q, and essentially no shunt. Almost all patients with type A COPD showed this pattern, and it was also seen in some patients with type B. (b) A pattern with large amounts of low but almost none of high VA/Q, and essentially no shunt. This pattern was found in 4 of 12 type B patients and 1 of type A. (c) A pattern with both low and high VA/Q areas was found in the remaining 6 patients. Distributions with high VA/Q areas occurred mostly in patients with greatly increased compliance and may represent loss of blood-glow due to alveolar wall destruction. Similarly, well-defined modes of low VA/Q areas were seen mostly in patients with severe cough and sputum and may be due to reduced ventilation secondary to mechanical airways obstruction or distortion. There was little change in the VA/Q distributions on exercise or on breathing 100% O2. The observed patterns of VA/Q inequality and shunt accounted for all of the hypoxemia at rest and during exercise. There was therefore no evidence for hypoxemia caused by diffusion impairment. Patients with similar arterial blood gases often had dissimilar VA/Q patterns. As a consequence the pattern of VA/Q inequality could not necessarily be inferred from the arterial PO2 and PCO2. PMID:833271

Wagner, P D; Dantzker, D R; Dueck, R; Clausen, J L; West, J B

1977-01-01

20

Separation of ventilation and perfusion related signals within EIT-data streams  

NASA Astrophysics Data System (ADS)

Electrical impedance tomography is a widely established technique for ventilation monitoring in the case of clinical research. To assess the capability of a patient's gas exchange, it is necessary to determine the regional supply of ventilation V as well as the local perfusion Q. Therefore, many approaches have been investigated to extract both signals from EIT-data, which would allow a V/Q-mapping. The challenge of this issue depends on the very weak perfusion related signal compared to the signal of ventilation. First approaches to visualize the perfusion were performed inducing apnea, ECG-gating or were based on Fourier series. Rather new techniques use principle component analysis (PCA) defining eigenvectors as a signal in time and thus try to determine "typical" ventilatory as well perfusion related signal streams. In this work, the algorithms of separation will be analyzed and compared (using apnea needs no separation and will not be discussed in this work).

Pikkemaat, R.; Leonhardt, S.

2010-04-01

21

Ventilation/Perfusion Scintigraphy in Children with Post-Infectious Bronchiolitis Obliterans: A Pilot Study  

PubMed Central

Purpose Childhood post-infectious bronchiolitis obliterans (BO) is an infrequent lung disease leading to narrowing and/or complete obliteration of small airways. Ventilation and perfusion (V/Q) scan can provide both regional and global pulmonary information. However, only few retrospective researches investigating post-infectious BO involved V/Q scan, the clinical value of this method is unknown. This preliminary prospective study was aimed to evaluate the correlation of V/Q scan with disease severity, pulmonary function test results, and prognosis in children with post-infectious BO. Methods Twenty-five post-infectious BO children (18 boys and 7 girls; mean age, 41 months) underwent V/Q scan and pulmonary function tests. Patients were followed after their inclusion. Ventilation index and perfusion index obtained from V/Q scan were used to measure pulmonary abnormalities. Spearman's rank correlation test of ventilation index and perfusion index on disease severity, lung function tests indices, and follow-up results were performed. Results The median follow-up period was 4.6 years (range, 2.2 to 5.0 years). Ventilation index and perfusion index were both correlated with disease severity (r?=?0.72, p<0.01 and r?=?0.73, p<0.01), but only ventilation index was related to pulmonary function tests results (all p<0.05). In addition, Spearman test yielded significant correlations between perfusion index and prognosis (r?=?0.77, p<0.01), and ventilation index and prognosis (r?=?0.63, p?=?0.01). Conclusions For children with post-infectious BO, the present study preliminarily indicated that the degree of ventilation and perfusion abnormalities evaluated by V/Q scan may be used to assess disease severity, and may be predictive of patient's outcome. PMID:24852165

Xie, Bo-Qia; Wang, Wei; Zhang, Wen-Qian; Guo, Xin-Hua; Yang, Min-Fu; Wang, Li; He, Zuo-Xiang; Tian, Yue-Qin

2014-01-01

22

Dynamic chest radiography with a flat-panel detector (FPD): ventilation-perfusion study  

NASA Astrophysics Data System (ADS)

Pulmonary ventilation and blood flow are reflected in dynamic chest radiographs as changes in X-ray translucency, i.e., pixel values. This study was performed to investigate the feasibility of ventilation-perfusion (V/Q) study based on the changes in pixel value. Sequential chest radiographs of a patient with ventilation-perfusion mismatch were obtained during respiration using a dynamic flat-panel detector (FPD) system. The lung area was recognized and average pixel value was measured in each area, tracking and deforming the region of interest. Inter-frame differences were then calculated, and the absolute values were summed in each respiratory phase. The results were visualized as ventilation, blood flow, V/Q ratio distribution map and compared to distribution of radioactive counts on ventilation and perfusion scintigrams. In the results, abnormalities were appeared as a reduction of changes in pixel values, and a correlation was observed between the distribution of changes in pixel value and those of radioactivity counts (Ventilation; r=0.78, Perfusion; r=0.77). V/Q mismatch was also indicated as mismatch of changes in pixel value, and a correlation with V/Q calculated by radioactivity counts (r=0.78). These results indicated that the present method is potentially useful for V/Q study as an additional examination in conventional chest radiography.

Tanaka, R.; Sanada, S.; Fujimura, M.; Yasui, M.; Tsuji, S.; Hayashi, N.; Okamoto, H.; Nanbu, Y.; Matsui, O.

2011-03-01

23

Perfusion and ventilation filters for Fourier-decomposition MR lung imaging.  

PubMed

MR imaging without the use of contrast agents has recently been used for creating perfusion and ventilation functional lung images. The technique incorporates frequency- or wavelet-domain filters to separate the MR signal components. This paper presents a new, subject-adaptive algorithm for perfusion and ventilation filters design. The proposed algorithm uses a lung signal model for separation of the signal components in the frequency domain. Non-stationary lung signals are handled by a short time Fourier transform. This method was applied to sets of 192 and 90 co-registered non-contrast MR lung images measured for five healthy subjects at the rate of 3,33 images per second, using different slice thicknesses. In each case, the resulted perfusion and ventilation images showed a smaller amount of mutual information, when compared to those obtained using the known lowpass/highpass filter approach. PMID:25466452

Wujcicki, Artur; Corteville, Dominique; Materka, Andrzej; Schad, Lothar R

2014-11-20

24

Optimization of isolated perfused/ventilated mouse lung to study hypoxic pulmonary vasoconstriction  

PubMed Central

Hypoxic pulmonary vasoconstriction (HPV) is a compensatory physiological mechanism in the lung that optimizes the matching of ventilation to perfusion and thereby maximizes gas exchange. Historically, HPV has been primarily studied in isolated perfused/ventilated lungs; however, the results of these studies have varied greatly due to different experimental conditions and species. Therefore, in the present study, we utilized the mouse isolated perfused/ventilated lung model for investigation of the role of extracellular Ca2+ and caveolin-1 and endothelial nitric oxide synthase expression on HPV. We also compared HPV using different perfusate solutions: Physiological salt solution (PSS) with albumin, Ficoll, rat blood, fetal bovine serum (FBS), or Dulbecco's Modified Eagle Medium (DMEM). After stabilization of the pulmonary arterial pressure (PAP), hypoxic (1% O2) and normoxic (21% O2) gases were applied via a ventilator in five-minute intervals to measure HPV. The addition of albumin or Ficoll with PSS did not induce persistent and strong HPV with or without a pretone agent. DMEM with the inclusion of FBS in the perfusate induced strong HPV in the first hypoxic challenge, but the HPV was neither persistent nor repetitive. PSS with rat blood only induced a small increase in HPV amplitude. Persistent and repetitive HPV occurred with PSS with 20% FBS as perfusate. HPV was significantly decreased by the removal of extracellular Ca2+ along with addition of 1 mM EGTA to chelate residual Ca2+ and voltage-dependent Ca2+ channel blocker (nifedipine 1 ?M). PAP was also reactive to contractile stimulation by high K+ depolarization and U46619 (a stable analogue of thromboxane A2). In summary, optimal conditions for measuring HPV were established in the isolated perfused/ventilated mouse lung. Using this method, we further confirmed that HPV is dependent on Ca2+ influx. PMID:24015341

Yoo, Hae Young; Zeifman, Amy; Ko, Eun A.; Smith, Kimberly A.; Chen, Jiwang; Machado, Roberto F.; Zhao, You-Yang; Minshall, Richard D.; Yuan, Jason X.-J.

2013-01-01

25

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

SciTech Connect

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

Lee, H.K.; Skarzynski, J.J.; Spadaro, A. (Mount Sinai Services-City Hospital Center, Elmhurst, NY (USA))

1989-12-01

26

Unusual ventilation perfusion scintigram in a case of immunologic pulmonary edema clinically simulating pulmonary embolism  

SciTech Connect

A case of immunologic pulmonary edema secondary to hydrochlorothiazide allergy developed in a 55-year-old woman that clinically simulated pulmonary embolism. The patient had abnormal washin images with normal washout images on an Xe-133 ventilation study. On the perfusion study, large bilateral central and posterior perfusion defects were present that showed an unusual mirror image pattern on the lateral and posterior oblique views. Resolution of radiographic and scintigraphic abnormalities occurred over a 3-day period in conjunction with corticosteroid therapy.

Campeau, R.J.; Faust, J.M.; Ahmad, S.

1987-11-01

27

Distribution of pulmonary ventilation and perfusion during short periods of weightlessness  

NASA Technical Reports Server (NTRS)

Airborne experiments were conducted on four trained normal male subjects (28-40 yr) to study pulmonary function during short periods (22-27 sec) of zero gravity obtained by flying a jet aircraft through appropriate parabolic trajectories. The cabin was always pressurized to a sea-level altitude. The discussion is limited to pulmonary ventilation and perfusion. The results clearly demonstrate that gravity is the major factor causing nonuniformity in the topographical distribution of pulmonary ventilation. More importantly, the results suggest that virtually all the topographical nonuniformity of ventilation, blood flow, and lung volume observed under 1-G conditions are eliminated during short periods of zero gravity.

Michels, D. B.; West, J. B.

1978-01-01

28

Electrical Impedance Tomography for assessing Ventilation/Perfusion mismatch for Pulmonary Embolism detection without interruptions in respiration.  

PubMed

Recent studies have shown high correlation between pulmonary perfusion mapping with impedance contrast enhanced Electrical Impedance Tomography (EIT) and standard perfusion imaging methods such as Computed Tomography (CT) and Single Photon Emission Computerized Tomography (SPECT). EIT has many advantages over standard imaging methods as it is highly portable and non-invasive. Contrast enhanced EIT uses hypertonic saline bolus instead of nephrotoxic contrast medium that are utilized by CT and nuclear Ventilation/Perfusion (V/Q) scans. However, current implementation of contrast enhanced EIT requires induction of an apnea period for perfusion measurement, rendering it disadvantageous compared with current gold standard imaging modalities. In the present paper, we propose the use of a wavelet denoising algorithm to separate perfusion signal from ventilation signal such that no interruption in patient's ventilation would be required. Furthermore, right lung to left lung perfusion ratio and ventilation ratio are proposed to assess the mismatch between ventilation and perfusion for detection of Pulmonary Embolism (PE). The proposed methodology was validated on an ovine model (n=3, 83.7±7.7 kg) with artificially induced PE in the right lung. The results showed a difference in right lung to left lung perfusion ratio between baseline and diseased states in all cases with all paired t-tests between baseline and PE yielding p <; 0.01, while the right lung to left lung ventilation ratio remained unchanged in two out of three experiments. Statistics were pooled from multiple repetitions of measurements per experiment. PMID:25571381

Doan Trang Nguyen; Thiagalingam, Aravinda; Bhaskaran, Abhishek; Barry, Michael A; Pouliopoulos, Jim; Jin, Craig; McEwan, Alistair L

2014-08-01

29

Computation of ventilation-perfusion ratio with Kr-81m in pulmonary embolism  

SciTech Connect

Diagnostic difficulties occur in pulmonary embolism (PE) during visual analysis of ventilation-perfusion images in matched defects or in chronic obstructive lung disease (COPD). In 44 patients with angiographically confirmed PE and in 40 patients with COPD, the regional ventilation-perfusion ratios (V/Q) were therefore computed using krypton-81m for each perfusion defect, and were displayed in a functional image. In patients with PE and mismatched defects, a high V/Q (1.96) was observed. A V/Q > 1.25 was also found in nine of 11 patients having PE and indeterminate studies (studies with perfusion abnormalities matched by radiographic abnormalities). COPD was characterized by matched defects and low V/Q. The percentage of patients correctly classified as having PE or COPD increased from 56% when considering the match or mismatched character to 88% when based on a V/Q of 1.25 in the region of the perfusion defect. This quantitative analysis, therefore, seems useful in classifying patients with scintigraphic suspicion of PE.

Meignan, M.; Simonneau, G.; Oliveira, L.; Harf, A.; Cinotti, L.; Cavellier, J.F.; Duroux, P.; Ansquer, J.C.; Galle, P.

1984-02-01

30

Ventilation-perfusion lung scanning in patients detected by a screening program for early lung carcinoma  

SciTech Connect

Ventilation-perfusion (V-P) lung scans obtained in 114 patients in a screening program for the early detection of lung cancer were reviewed, and abnormalities were correlated with radiographic and surgical findings. Eighty-seven patients eventually had a tissue diagnosis of carcinoma; 65 (75%) had a perfusion defect and 56 (67%) had a ventilation abnormality at the tumor site. Lobar or segmental perfusion abnormalities were present at the tumor site in two of 13 patients whose lung cancer could not be localized by chest radiographs. However, 12 of these 13 patients and 54% of those with radiographically visible lesions had perfusion abnormalities in other lung regions. Twenty-seven patients with suspected carcinoma who were subsequently proved to have benign lesions had V-P abnormalities similar to those in patients with lung cancer. Thus, no pattern of V-P abnormalities allowed lung cancer in this screened population to be reliably distinguished from coexisting airway disease or nonmalignant pulmonary masses. V-P lung studies have a limited role in the early detection of lung cancer.

Katz, R.D.; Alderson, P.O.; Tockman, M.S.

1981-10-01

31

Ventilation-perfusion relationships in the lung during head-out water immersion  

NASA Technical Reports Server (NTRS)

Mechanisms of altered pulmonary gas exchange during water immersion were studied in 12 normal males: 6 young (aged 20-29) and 6 older (aged 40-45). It is concluded that, in young subjects with closing volume (CV) less than expiratory reserve volume (ERV), gas exchange was enhanced during immersion, because normal ventilation-perfusion relations were preserved, and by mass balance, the ventilation/O2 uptake changes elevated arterial P(O2). In older males with CV greater than ERV and 52 percent of tidal volume below CV, immersion-induced airways closure during tidal breathing was associated with minimally increased shunt that did not significantly impair gas exchange. It is suggested that airways closure of this degree is of little importance to gas exchange.

Derion, Toniann; Guy, Harold J. B.; Tsukimoto, Koichi; Schaffartzik, Walter; Prediletto, Renato; Poole, David C.; Knight, Douglas R.; Wagner, Peter D.

1992-01-01

32

Ventilation-perfusion scintigraphy in an adult with congenital unilateral hyperlucent lung  

SciTech Connect

A variety of congenital and acquired etiologies can give rise to the radiographic finding of a unilateral hyperlucent lung. An unusual case of congenital lobar emphysema diagnosed in a young adult following the initial discovery of a hyperexpanded, hyperlucent lung is reported. Although subsequent bronchoscopy and radiologic studies detailed extensive anatomic abnormalities, functional imaging also played an important role in arriving at this rare diagnosis. In particular, ventilation-perfusion scintigraphy identified the small contralateral lung as the functional lung and helped narrow the differential diagnosis to etiologies involving obstructive airway disorders.

Wegener, W.A.; Velchik, M.G. (Hospital of the University of Pennsylvania, Philadelphia (USA))

1990-10-01

33

Feasibility of Combining MR Perfusion, Angiography, and 3He Ventilation Imaging for Evaluation of Lung Function in a Porcine Model  

PubMed Central

Rationale and Objective To assess the feasibility of combining magnetic resonance (MR) perfusion, angiography, and 3He ventilation imaging for the evaluation of lung function in a porcine model. Materials and Methods Fourteen consecutive porcine models with externally delivered pulmonary emboli and/or airway occlusions were examined with MR perfusion, angiography, and 3He ventilation imaging. Ultrafast gradient-echo sequences were used for 3D perfusion and angiographic imaging, in conjunction with the use of contrast-agent injections. 2D multiple-section 3He imaging was performed subsequently via the inhalation of hyperpolarized 3He gas. The diagnostic accuracy of MR angiography for detecting pulmonary emboli was determined by two reviewers. The diagnostic confidence for different combinations of MR techniques was rated on the basis of a 5-point grading scale (5 = definite). Results The sensitivity, specificity, and accuracy of MR angiography for detecting pulmonary emboli were approximately 85.7%, 90.5%, and 88.1%, respectively. The interobserver agreement was very strong (k = 0.82). There was a clear tendency for confidence to increase when first perfusion and then ventilation imaging were added to the angiographic image (Wilcoxon signed ranks test, P = 0.03). Conclusion The combination of the three methods of MR perfusion, angiography, and 3H ventilation imaging may provide complementary information on abnormal lung anatomy and function. PMID:15721597

Hong, Cheng; Leawoods, Jason C.; Yablonskiy, Dmitriy A.; Leyendecker, John R.; Bae, Kyongtae T.; Pilgram, Thomas K.; Woodard, Pamela K.; Conradi, Mark S.; Zheng, Jie

2007-01-01

34

Regional ventilation-perfusion distribution is more uniform in the prone position  

NASA Technical Reports Server (NTRS)

The arterial blood PO(2) is increased in the prone position in animals and humans because of an improvement in ventilation (VA) and perfusion (Q) matching. However, the mechanism of improved VA/Q is unknown. This experiment measured regional VA/Q heterogeneity and the correlation between VA and Q in supine and prone positions in pigs. Eight ketamine-diazepam-anesthetized, mechanically ventilated pigs were studied in supine and prone positions in random order. Regional VA and Q were measured using fluorescent-labeled aerosols and radioactive-labeled microspheres, respectively. The lungs were dried at total lung capacity and cubed into 603-967 small ( approximately 1.7-cm(3)) pieces. In the prone position the homogeneity of the ventilation distribution increased (P = 0.030) and the correlation between VA and Q increased (correlation coefficient = 0.72 +/- 0.08 and 0.82 +/- 0.06 in supine and prone positions, respectively, P = 0.03). The homogeneity of the VA/Q distribution increased in the prone position (P = 0.028). We conclude that the improvement in VA/Q matching in the prone position is secondary to increased homogeneity of the VA distribution and increased correlation of regional VA and Q.

Mure, M.; Domino, K. B.; Lindahl, S. G.; Hlastala, M. P.; Altemeier, W. A.; Glenny, R. W.

2000-01-01

35

Validation of measurements of ventilation-to-perfusion ratio inequality in the lung from expired gas  

NASA Technical Reports Server (NTRS)

The analysis of the gas in a single expirate has long been used to estimate the degree of ventilation-perfusion (Va/Q) inequality in the lung. To further validate this estimate, we examined three measures of Va/Q inhomogeneity calculated from a single full exhalation in nine anesthetized mongrel dogs under control conditions and after exposure to aerosolized methacholine. These measurements were then compared with arterial blood gases and with measurements of Va/Q inhomogeneity obtained using the multiple inert gas elimination technique. The slope of the instantaneous respiratory exchange ratio (R slope) vs. expired volume was poorly correlated with independent measures, probably because of the curvilinear nature of the relationship due to continuing gas exchange. When R was converted to the intrabreath Va/Q (iV/Q), the best index was the slope of iV/Q vs. volume over phase III (iV/Q slope). This was strongly correlated with independent measures, especially those relating to inhomogeneity of perfusion. The correlations for iV/Q slope and R slope considerably improved when only the first half of phase III was considered. We conclude that a useful noninvasive measurement of Va/Q inhomogeneity can be derived from the intrabreath respiratory exchange ratio.

Prisk, G. Kim; Guy, Harold J B.; West, John B.; Reed, James W.

2003-01-01

36

Spatial correspondence of 4D CT ventilation and SPECT pulmonary perfusion defects in patients with malignant airway stenosis  

NASA Astrophysics Data System (ADS)

To determine the spatial overlap agreement between four-dimensional computed tomography (4D CT) ventilation and single photon emission computed tomography (SPECT) perfusion hypo-functioning pulmonary defect regions in a patient population with malignant airway stenosis. Treatment planning 4D CT images were obtained retrospectively for ten lung cancer patients with radiographically demonstrated airway obstruction due to gross tumor volume. Each patient also received a SPECT perfusion study within one week of the planning 4D CT, and prior to the initiation of treatment. Deformable image registration was used to map corresponding lung tissue elements between the extreme component phase images, from which quantitative three-dimensional (3D) images representing the local pulmonary specific ventilation were constructed. Semi-automated segmentation of the percentile perfusion distribution was performed to identify regional defects distal to the known obstructing lesion. Semi-automated segmentation was similarly performed by multiple observers to delineate corresponding defect regions depicted on 4D CT ventilation. Normalized Dice similarity coefficient (NDSC) indices were determined for each observer between SPECT perfusion and 4D CT ventilation defect regions to assess spatial overlap agreement. Tidal volumes determined from 4D CT ventilation were evaluated versus measurements obtained from lung parenchyma segmentation. Linear regression resulted in a linear fit with slope = 1.01 (R2 = 0.99). Respective values for the average DSC, NDSC1 mm and NDSC2 mm for all cases and multiple observers were 0.78, 0.88 and 0.99, indicating that, on average, spatial overlap agreement between ventilation and perfusion defect regions was comparable to the threshold for agreement within 1-2 mm uncertainty. Corresponding coefficients of variation for all metrics were similarly in the range: 0.10%-19%. This study is the first to quantitatively assess 3D spatial overlap agreement between clinically acquired SPECT perfusion and specific ventilation from 4D CT. Results suggest high correlation between methods within the sub-population of lung cancer patients with malignant airway stenosis.

Castillo, Richard; Castillo, Edward; McCurdy, Matthew; Gomez, Daniel R.; Block, Alec M.; Bergsma, Derek; Joy, Sarah; Guerrero, Thomas

2012-04-01

37

Influence of Perfusion and Ventilation Scans on Therapeutic Decision Making and Outcome in Cases of Possible Embolism  

PubMed Central

We examined the influence of perfusion (Q) and ventilation (V) scans on therapeutic decision making and outcome among 229 patients referred for lung scans because embolism was suggested and found that specific V/Q scan patterns strongly influenced postscan decisions regarding initiation, maintenance or cessation of heparin therapy. These therapeutic decisions bore a relationship to outcome (recurrences and death) and disclosed decision-making deficits that need remedy by future investigational and educational efforts. PMID:4013250

Mercandetti, Alex J.; Kipper, Michael S.; Moser, Kenneth M.

1985-01-01

38

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

39

Determination of regional ventilation and perfusion in the lung using xenon and computed tomography.  

PubMed

We propose a model to measure both regional ventilation (V) and perfusion (Q) in which the regional radiodensity (RD) in the lung during xenon (Xe) washin is a function of regional V (increasing RD) and Q (decreasing RD). We studied five anesthetized, paralyzed, mechanically ventilated, supine sheep. Four 2.5-mm-thick computed tomography (CT) images were simultaneously acquired immediately cephalad to the diaphragm at end inspiration for each breath during 3 min of Xe breathing. Observed changes in RD during Xe washin were used to determine regional V and Q. For 16 mm(3), Q displayed more variance than V: the coefficient of variance of Q (CV(Q)) = 1.58 +/- 0.23, the CV of V (CV(V)) = 0.46 +/- 0.07, and the ratio of CV(Q) to CV(V) = 3.5 +/- 1.1. CV(Q) (1.21 +/- 0.37) and the ratio of CV(Q) to CV(V) (2.4 +/- 1.2) were smaller at 1,000-mm(3) scale, but CV(V) (0.53 +/- 0.09) was not. V/Q distributions also displayed scale dependence: log SD of V and log SD of Q were 0.79 +/- 0.05 and 0.85 +/- 0.10 for 16-mm(3) and 0.69 +/- 0.20 and 0.67 +/- 0.10 for 1,000-mm(3) regions of lung, respectively. V and Q measurements made with CT and Xe also demonstrate vertically oriented and isogravitational heterogeneity, which are described using other methodologies. Sequential images acquired by CT during Xe breathing can be used to determine both regional V and Q noninvasively with high spatial resolution. PMID:11568158

Kreck, T C; Krueger, M A; Altemeier, W A; Sinclair, S E; Robertson, H T; Shade, E D; Hildebrandt, J; Lamm, W J; Frazer, D A; Polissar, N L; Hlastala, M P

2001-10-01

40

Krypton 81m ventilation/perfusion ratios (V/Q) measured in lateral decubitus in pulmonary embolism (P. E. )  

SciTech Connect

In normal subjects lateral decubitis induces in both independent (lower) and nondependent lung (upper), major changes in perfusion, ventilation and V/Q ratios which can be studied with the short life radioisotope Krypton 81m. Regional V/Q are computed from ventilation and perfusion scans, successively obtained with a gamma camera linked to a computer by continuous inhalation or infusion of this gas during tidal breathing. They were displayed as a color coded functional image. To assess the effect of posture on V/Q in P.E. and other diseases which decrease the regional perfusion, 32 patients with unilateral lung diseases were studied in supine posture and both lateral decubitis: 8 with proved P.E., (3 out of them having radiological opacity matching the perfusion defect), 9 with bullous emphysema, 6 with bronchogenic carcinoma, 9 with acute bacterial pneumonia. V/Q were computed in the region of the perfusion defect. In P.E. the mean V/Q was high (1.92 +- 0.6 SD), and did not change whatever the posture. Conversely major changes of V/Q were induced with postural changes in bullous emphysema and lung carcinoma whatever the V/Q in patient supine. In pneumonia low V/Q were observed in supine posture (.73 +- .2). They decreased significantly when the pneumonia was dependent (.53 +- .2 p < 0.02) and increased in the controlateral decubitis (1.07 +- .3, p < 0.001). Since posture has no or little effect on regional V/Q in P.E., it can be used to discriminate P.E., even in the case of radiological opacity, from other unilateral disease inducing perfusion defect.

Meignan, M.; Cinotti, L.; Harf, A.; Oliveira, L.; Simonneau, G.

1984-01-01

41

Automatic extraction of PIOPED interpretations from ventilation/perfusion lung scan reports.  

PubMed

Free-text documents are the main type of data produced by a radiology department in a hospital information system. While this type of data is readily accessible for clinical data review it can not be accessed by other applications to perform medical decision support, quality assurance, and outcome studies. In an attempt to solve this problem, natural language processing systems have been developed and tested against chest x-rays reports to extract relevant clinical information and make it accessible to other computer applications. We have used a natural language processing tool called SymText to extract relevant clinical information from a different type of radiology report, the Ventilation/Perfusion lung scan report. Results of this effort can be analyzed in terms of precision and recall. The overall precision was 0.88 and recall was 0.92. In addition, the natural language processing system functions differently in reports with and without an impression section. If this type of information can be successfully extracted from radiology reports, one can develop quality monitors for the diagnostic performance of the radiologist by correlating the impressions with gold standard data present in a hospital information system. Avoiding the manual effort previously necessary to create quality assurance data, can lead to a higher frequency of quality review in a radiology department. PMID:9929341

Fiszman, M; Haug, P J; Frederick, P R

1998-01-01

42

Impact of ventilation/perfusion single-photon emission computed tomography on treatment duration of pulmonary embolism  

PubMed Central

Purpose The aim of the study was to establish whether the duration of anticoagulant (AC) therapy can be tailored, on an objective basis, by using ventilation/perfusion single-photon emission computed tomography (V/P SPECT) and to assess the extent of residual perfusion defects over time. In particular, we addressed the following: (a) is the extent of perfusion recovery at 3 months of initial pulmonary embolism (PE) diagnosis a satisfactory criterion for deciding the duration of oral AC? (b) Is it safe to withdraw AC at 3 months if perfusion recovery is complete? Patients and methods Of 269 consecutive patients with suspected PE, 100 patients were diagnosed with PE using V/P SPECT. Sixty-seven patients with acute PE were followed up clinically and with V/P SPECT at 3 months. Sixty-four patients were subject to review and examination using V/P SPECT for a period of 6 months and 33 were followed up only clinically. Therapy was terminated after 3 months if perfusion was normalized, and patients were free of symptoms and the risk of hypercoagulability. Initial extension of PE did not have an impact on decision making. Results PE extension varied from 10 to 70% in the acute stage. After 3 months, complete resolution of PE was found in 48 patients. The treating pulmonologist decided to terminate therapy in 35 (73%) patients and to continue AC in 13 patients because of persistent risk factors. Six months later, at the second control stage, 53 patients had complete recovery of pulmonary perfusion. Eleven patients still had perfusion defects at 6 months. No recurrence was identified at 6 months in the 35 patients whose therapy was terminated after 3 months. No bleeding effects were observed in any of the patients during the 6-month follow-up. Conclusion This study shows that AC therapy can be tailored, on an objective basis, by using V/P SPECT. Normalization of perfusion at 3 months of initial PE diagnosis was a reliable indicator that AC could be safely withdrawn in patients who were without hypercoagulability risk. PMID:25321156

Begic, Amela; Opankovi?, Emina; ?uki?, Vesna; Rustempaši?, Medzida; Baši?, Amila; Miniati, Massimo; Jögi, Jonas

2015-01-01

43

Continuous monitoring of cortical perfusion by laser Doppler flowmetry in ventilated patients with head injury.  

PubMed Central

A method for monitoring cortical perfusion by laser Doppler flowmetry (LDF) in the neurointensive care unit is described. Out of 22 patients with head injuries, reliable and long term recordings were obtained in 16. Laser Doppler flowmetry registered changes in cortical microcirculatory flow in response to spontaneous waves of raised intracranial pressure, and to therapeutic manoeuvres that altered the cerebral perfusion pressure. Comparisons of variations in flux signal with cerebral perfusion pressure provided an indication of the autoregulatory state of the cortical microcirculation, and analysis of raw LDF data demonstrated an autoregulatory breakpoint of cerebral perfusion pressure of 58 mm Hg, below which cortical perfusion failed. Although middle cerebral artery flow velocities were generally tightly coupled with LDF signal changes, episodes of uncoupling were seen. The potential uses and limitations of LDF in the neurointensive care setting are discussed. Images PMID:7964816

Kirkpatrick, P J; Smielewski, P; Czosnyka, M; Pickard, J D

1994-01-01

44

Bronchopulmonary dysplasia: clinical grading in relation to ventilation/perfusion mismatch measured by single photon emission computed tomography.  

PubMed

Bronchopulmonary dysplasia (BPD) is a significant cause of morbidity in the preterm population. Clinical severity grading based on the need for supplemental oxygen and/or need for positive airway pressure at 36 weeks postmenstrual age does not yield reproducible predictive values for later pulmonary morbidity. Single photon emission computed tomography (SPECT) was used to measure the distribution of lung ventilation (V) and perfusion (Q) in 30 BPD preterm infants at a median age of 37 weeks postmenstrual age. The V and Q were traced with 5?MBq Technegas and Technetium-labeled albumin macro aggregates, respectively, and the V/Q match-mismatch was used to quantify the extent of lung function impairment. The latter was then compared with the clinical severity grading at 36 weeks, and time spent on mechanical ventilation, continuous positive airway pressure (CPAP) and supplemental oxygen. Of those with mild and moderate BPD 3/9 and 3/11 patients, respectively, showed significant V/Q mismatches. By contrast, 4/10 patients with severe BPD showed a satisfactory V/Q matching distribution. An unsatisfactory V/Q match was not correlated with time spent on supplemental oxygen or CPAP, but was significantly negatively correlated with time spent on mechanical ventilation. SPECT provides unique additional information about regional lung function. The results suggest that the current clinical severity grading can be improved and/or complemented with SPECT. PMID:23359534

Kjellberg, Malin; Björkman, Karin; Rohdin, Malin; Sanchez-Crespo, Alejandro; Jonsson, Baldvin

2013-12-01

45

The gravitational distribution of ventilation-perfusion ratio is more uniform in prone than supine posture in the normal human lung  

PubMed Central

The gravitational gradient of intrapleural pressure is suggested to be less in prone posture than supine. Thus the gravitational distribution of ventilation is expected to be more uniform prone, potentially affecting regional ventilation-perfusion (V?a/Q?) ratio. Using a novel functional lung magnetic resonance imaging technique to measure regional V?a/Q? ratio, the gravitational gradients in proton density, ventilation, perfusion, and V?a/Q? ratio were measured in prone and supine posture. Data were acquired in seven healthy subjects in a single sagittal slice of the right lung at functional residual capacity. Regional specific ventilation images quantified using specific ventilation imaging and proton density images obtained using a fast gradient-echo sequence were registered and smoothed to calculate regional alveolar ventilation. Perfusion was measured using arterial spin labeling. Ventilation (ml·min?1·ml?1) images were combined on a voxel-by-voxel basis with smoothed perfusion (ml·min?1·ml?1) images to obtain regional V?a/Q? ratio. Data were averaged for voxels within 1-cm gravitational planes, starting from the most gravitationally dependent lung. The slope of the relationship between alveolar ventilation and vertical height was less prone than supine (?0.17 ± 0.10 ml·min?1·ml?1·cm?1 supine, ?0.040 ± 0.03 prone ml·min?1·ml?1·cm?1, P = 0.02) as was the slope of the perfusion-height relationship (?0.14 ± 0.05 ml·min?1·ml?1·cm?1 supine, ?0.08 ± 0.09 prone ml·min?1·ml?1·cm?1, P = 0.02). There was a significant gravitational gradient in V?a/Q? ratio in both postures (P < 0.05) that was less in prone (0.09 ± 0.08 cm?1 supine, 0.04 ± 0.03 cm?1 prone, P = 0.04). The gravitational gradients in ventilation, perfusion, and regional V?a/Q? ratio were greater supine than prone, suggesting an interplay between thoracic cavity configuration, airway and vascular tree anatomy, and the effects of gravity on V?a/Q? matching. PMID:23620488

Sá, Rui Carlos; Theilmann, Rebecca J.; Buxton, Richard B.; Prisk, G. Kim; Hopkins, Susan R.

2013-01-01

46

Evaluation of a computer program for non-invasive determination of pulmonary shunt and ventilation-perfusion mismatch.  

PubMed

We describe a three-compartment model (shunt and two perfused compartments) to analyse the relationship between inspired oxygen (FIO2) and arterial oxygen saturation (SaO2) in terms of pulmonary shunt and ventilation-perfusion ratio (VA/Q). The program was tested using 24 exact datasets, each with six pairs of FIO2 and SaO2 data points with known VA/Q and shunt, generated by a complex calculator of gas exchange. Additional datasets were created by adding noise and rounding the exact sets, and by reducing the number of data points per dataset. The importance of the oxyhaemoglobin dissociation curve and the arterio-venous difference in oxygen content (avDO2) were also tested. Analysis using the three compartment model was more accurate than the two compartment model and less affected by data degradation. The absolute error in shunt estimation was never more than 2.2 % for the exact and rounded datasets, but the error in VA/Q estimation was -29 to 19 % of the true value (10th-90th centiles). The characteristics of the well-ventilated compartment were not determined accurately. At extremes of cardiac output, an assumed value of avDO2 resulted in significant errors. It is probably advantageous to correct for foetal haemoglobin in neonatal datasets. Analysis of FIO2 versus SaO2 datasets using a three compartment model provides accurate estimates of shunt and VA/Q when arterio-venous difference in oxygen content is known. The estimates may have value as objective measures of gas exchange, and as a visual guide for oxygen therapy. PMID:24402641

Lockwood, Geoffrey G; Fung, Nick L S; Jones, J Gareth

2014-12-01

47

Role of spiral volumetric computed tomographic scanning in the assessment of patients with clinical suspicion of pulmonary embolism and an abnormal ventilation\\/perfusion lung scan  

Microsoft Academic Search

BACKGROUND: A study was carried out to evaluate the potential place of spiral volumetric computed tomography (SVCT) in the diagnostic strategy for pulmonary embolism. METHODS: In a prospective study 249 patients with clinical suspicion of pulmonary embolism were evaluated with various imaging techniques. In all patients a ventilation\\/perfusion (V\\/Q) scan was performed. Seventy seven patients with an abnormal V\\/Q scan

A. B. van Rossum; F. E. Treurniet; G. J. Kieft; S. J. Smith; R. Schepers-Bok

1996-01-01

48

Imaging of the three-dimensional alveolar structure and the alveolar mechanics of a ventilated and perfused isolated rabbit lung with Fourier domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

In this feasibility study, Fourier domain optical coherence tomography (FDOCT) is used for visualizing the 3-D structure of fixated lung parenchyma and to capture real-time cross sectional images of the subpleural alveolar mechanics in a ventilated and perfused isolated rabbit lung. The compact and modular setup of the FDOCT system allows us to image the first 500 µm of subpleural lung parenchyma with a 3-D resolution of 16×16×8 µm (in air). During mechanical ventilation, real-time cross sectional FDOCT images visualize the inflation and deflation of alveoli and alveolar sacks (acini) in successive images of end-inspiratory and end-expiratory phase. The FDOCT imaging shows the relation of local alveolar mechanics to the setting of tidal volume (VT), peak airway pressure, and positive end-expiratory pressure (PEEP). Application of PEEP leads to persistent recruitment of alveoli and acini in the end-expiratory phase, compared to ventilation without PEEP where alveolar collapse and reinflation are observed. The imaging of alveolar mechanics by FDOCT will help to determine the amount of mechanical stress put on the alveolar walls during tidal ventilation, which is a key factor in understanding the development of ventilator induced lung injury (VILI).

Popp, Alexander; Wendel, Martina; Knels, Lilla; Koch, T.; Koch, Edmund

2006-01-01

49

CHARGE IMBALANCE  

SciTech Connect

The purpose of this article is to review the theory of charge imbalance, and to discuss its relevance to a number of experimental situations. We introduce the concepts of quasiparticle charge and charge imbalance, and discuss the generation and detection of charge imbalance by tunneling. We describe the relaxation of the injected charge imbalance by inelastic scattering processes, and show how the Boltzmann equation can be solved to obtain the steady state quasiparticle distribution and the charge relaxation rate. Details are given of experiments to measure charge imbalance and the charge relaxation rate when inelastic scattering is the predominant relaxation mechanism. Experiments on and theories of other charge relaxation mechanisms are discussed, namely relaxation via elastic scattering in the presence of energy gap anisotropy, or in the presence of a pair breaking mechanism such as magnetic impurities or an applied supercurrent or magnetic field. We describe three other situations in which charge imbalance occurs, namely the resistance of the NS interface, phase slip centers, and the flow of a supercurrent in the presence of a temperature gradient.

Clarke, John

1980-09-01

50

Changes in Global Function and Regional Ventilation and Perfusion on SPECT During the Course of Radiotherapy in Patients With Non-Small-Cell Lung Cancer  

SciTech Connect

Purpose: This study aimed to (1) examine changes in dyspnea, global pulmonary function test (PFT) results, and functional activity on ventilation (V)/perfusion (Q) single-photon emission computerized tomography (SPECT) scans during the course of radiation (RT), and (2) factors associated with the changes in patients with non-small-cell lung cancer (NSCLC). Methods and Materials: Fifty-six stage I to III NSCLC patients treated with definitive RT with or without chemotherapy were enrolled prospectively. Dyspnea was graded according to Common Terminology Criteria for Adverse Events version 3.0 prior to and weekly during RT. V/Q SPECT-computed tomography (CT) and PFTs were performed prior to and during RT at approximately 45 Gy. Functions of V and Q activities were assessed using a semiquantitative scoring of SPECT images. Results: Breathing improved significantly at the third week (mean dyspnea grade, 0.8 vs. 0.6; paired t-test p = 0.011) and worsened during the later course of RT (p > 0.05). Global PFT results did not change significantly, while regional lung function on V/Q SPECT improved significantly after {approx}45 Gy. The V defect score (DS) was 4.9 pre-RT versus 4.3 during RT (p = 0.01); Q DS was 4.3 pre-RT versus 4.0 during RT (p < 0.01). Improvements in V and Q functions were seen primarily in the ipsilateral lung (V DS, 1.9 pre-RT versus 1.4 during RT, p < 0.01; Q DS, 1.7 pre-RT versus 1.5 during RT, p < 0.01). Baseline primary tumor volume was significantly correlated with pre-RT V/Q DS (p < 0.01). Patients with central lung tumors had greater interval changes in V and Q than those with more peripheral tumors (p <0.05 for both V and Q DS). Conclusions: Regional ventilation and perfusion improved during RT at 45 Gy. This suggests that adaptive planning based on V/Q SPECT during RT may allow sparing of functionally recoverable lung tissue.

Yuan Shuanghu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiation Oncology, Shaexamndong Cancer Hospital and Institute, Jinan (China); Frey, Kirk A.; Gross, Milton D. [Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Hayman, James A. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Arenberg, Doug [Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (United States); Cai Xuwei [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Ramnath, Nithya; Hassan, Khaled [Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (United States); Moran, Jean; Eisbruch, Avraham; Ten Haken, Randall K. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Kong Fengming, E-mail: fengkong@med.umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Radiation Oncology, Veterans' Affairs Health Center, Ann Arbor, Michigan (United States)

2012-03-15

51

A compartment model of alveolar-capillary oxygen diffusion with ventilation-perfusion gradient and dynamics of air transport through the respiratory tract.  

PubMed

This paper presents a model of alveolar-capillary oxygen diffusion with dynamics of air transport through the respiratory tract. For this purpose electrical model representing the respiratory tract mechanics and differential equations representing oxygen membrane diffusion are combined. Relevant thermodynamic relations describing the mass of oxygen transported into the human body are proposed as the connection between these models, as well as the influence of ventilation-perfusion mismatch on the oxygen diffusion. The model is verified based on simulation results of varying exercise intensities and statistical calculations of the results obtained during various clinical trials. The benefit of the approach proposed is its application in simulation-based research aimed to generate quantitative data of normal and pathological conditions. Based on the model presented, taking into account many essential physiological processes and air transport dynamics, comprehensive and combined studies of the respiratory efficiency can be performed. The impact of physical exercise, precise changes in respiratory tract mechanics and alterations in breathing pattern can be analyzed together with the impact of various changes in alveolar-capillary oxygen diffusion. This may be useful in simulation of effects of many severe medical conditions and increased activity level. PMID:24950449

Jaworski, Jacek; Redlarski, Grzegorz

2014-08-01

52

Non?invasive measurement of reduced ventilation:perfusion ratio and shunt in infants with bronchopulmonary dysplasia: a physiological definition of the disease  

PubMed Central

Background An objective definition of bronchopulmonary dysplasia (BPD) is required to interpret trial outcomes and provide a baseline for prognostic studies. Current definitions do not quantify disease severity. The cardinal measures of impaired gas exchange are a reduced ventilation:perfusion ratio (VA:Q) and increased right to left shunt. These can be determined non?invasively by plotting arterial oxygen saturation (Spo2) against inspired oxygen pressure (PIo2). Aims To describe the reduced VA:Q and shunt in infants with BPD and evaluate these as graded measures of pulmonary dysfunction. Methods 21 preterm infants with BPD were studied. PIo2 was changed stepwise to vary Spo2 between 86% and 94%. Pairs of PIo2 and Spo2 data points for each infant were plotted and analysed to derive reduced VA:Q ratio and shunt. Results In every infant, the Spo2 versus PIo2 curve was shifted to the right of the normal because of a reduced VA:Q. The mean (SD) shift was 16.5 (4.7)?kPa (normal 6?kPa). Varying degrees of shunt were also present, but these were less important in determining Spo2 within the studied range. The degree of shift was strongly predictive of the PIo2 required to achieve any Spo2 within the range 86–94% (R2>0.9), permitting shift and VA:Q to be determined from a single pair of PIo2 and SpO2 values in this range. Conclusions The predominant gas exchange impairment in BPD is a reduced VA:Q, described by the right shift of the Spo2 versus PIo2 relationship. This provides a simpler method for defining BPD, which can grade disease severity. PMID:16798787

Quine, D; Wong, C M; Boyle, E M; Jones, J G; Stenson, B J

2006-01-01

53

Pulmonary ventilation/perfusion scan  

MedlinePLUS

... lung areas) lung function in people with advanced pulmonary disease , such as COPD ... any of the following: Airway obstruction Chronic obstructive pulmonary disease (COPD) Pneumonia Narrowing of the pulmonary artery Pneumonitis ...

54

Noninvasive ventilation in trauma  

PubMed Central

Trauma patients are a diverse population with heterogeneous needs for ventilatory support. This requirement depends mainly on the severity of their ventilatory dysfunction, degree of deterioration in gaseous exchange, any associated injuries, and the individual feasibility of potentially using a noninvasive ventilation approach. Noninvasive ventilation may reduce the need to intubate patients with trauma-related hypoxemia. It is well-known that these patients are at increased risk to develop hypoxemic respiratory failure which may or may not be associated with hypercapnia. Hypoxemia in these patients is due to ventilation perfusion mismatching and right to left shunt because of lung contusion, atelectasis, an inability to clear secretions as well as pneumothorax and/or hemothorax, all of which are common in trauma patients. Noninvasive ventilation has been tried in these patients in order to avoid the complications related to endotracheal intubation, mainly ventilator-associated pneumonia. The potential usefulness of noninvasive ventilation in the ventilatory management of trauma patients, though reported in various studies, has not been sufficiently investigated on a large scale. According to the British Thoracic Society guidelines, the indications and efficacy of noninvasive ventilation treatment in respiratory distress induced by trauma have thus far been inconsistent and merely received a low grade recommendation. In this review paper, we analyse and compare the results of various studies in which noninvasive ventilation was applied and discuss the role and efficacy of this ventilator modality in trauma. PMID:25685722

Karcz, Marcin K; Papadakos, Peter J

2015-01-01

55

Noninvasive ventilation in trauma.  

PubMed

Trauma patients are a diverse population with heterogeneous needs for ventilatory support. This requirement depends mainly on the severity of their ventilatory dysfunction, degree of deterioration in gaseous exchange, any associated injuries, and the individual feasibility of potentially using a noninvasive ventilation approach. Noninvasive ventilation may reduce the need to intubate patients with trauma-related hypoxemia. It is well-known that these patients are at increased risk to develop hypoxemic respiratory failure which may or may not be associated with hypercapnia. Hypoxemia in these patients is due to ventilation perfusion mismatching and right to left shunt because of lung contusion, atelectasis, an inability to clear secretions as well as pneumothorax and/or hemothorax, all of which are common in trauma patients. Noninvasive ventilation has been tried in these patients in order to avoid the complications related to endotracheal intubation, mainly ventilator-associated pneumonia. The potential usefulness of noninvasive ventilation in the ventilatory management of trauma patients, though reported in various studies, has not been sufficiently investigated on a large scale. According to the British Thoracic Society guidelines, the indications and efficacy of noninvasive ventilation treatment in respiratory distress induced by trauma have thus far been inconsistent and merely received a low grade recommendation. In this review paper, we analyse and compare the results of various studies in which noninvasive ventilation was applied and discuss the role and efficacy of this ventilator modality in trauma. PMID:25685722

Karcz, Marcin K; Papadakos, Peter J

2015-02-01

56

Imbalance rotating machine balancing  

NASA Astrophysics Data System (ADS)

Imbalance analysis is essential in the rotating machine. However, some problems still remain in the aspects of computational efficiency and accuracy. In the present paper, a new method was proposed for estimating the mass imbalance of a rotating shaft by using the vibration signals. This is a new method for the detection of a mass imbalance and its phase position. Based on the signal processing with FFT, an estimator was designed to detect the mass of imbalance. And an improved Lissajous diagram was also introduced with statistical analysis, which make it possible to compute the phase position of the mass imbalance efficiently and arranged at a certain location of the shaft. The proposed method was demonstrated and validated through several test examples.

Su, Hua; Choi, Han-Soo; Chong, Kil To

2005-12-01

57

Ventilation and ventilators.  

PubMed

The history of ventilation is reviewed briefly and recent developments in techniques of ventilation are discussed. Operating features of ventilators have changed in the past few years, partly as the result of clinical progress; yet, technology appears to have outstripped the clinician's ability to harness it most effectively. Clinical discipline and training of medical staff in the use of ventilators could be improved. The future is promising if clinician and designer can work together closely. Ergonomics of ventilators and their controls and the provision of alarms need special attention. Microprocessors are likely to feature prominently in the next generation of designs. PMID:6754938

Hayes, B

1982-01-01

58

The added value of hybrid ventilation/perfusion SPECT/CT in patients with stable COPD or apparently healthy smokers. Cancer-suspected CT findings in the lungs are common when hybrid imaging is used  

PubMed Central

Ventilation/perfusion (V/P) single-photon emission computed tomography (SPECT) is recognized as a diagnostic method with potential beyond the diagnosis of pulmonary embolism. V/P SPECT identifies functional impairment in diseases such as heart failure (HF), pneumonia, and chronic obstructive pulmonary disease (COPD). The development of hybrid SPECT/computed tomography (CT) systems, combining functional with morphological imaging through the addition of low-dose CT (LDCT), may be useful in COPD, as these patients are prone to lung cancer and other comorbidities. The aim of this study was to investigate the added value of LDCT among healthy smokers and patients with stable COPD, when examined with V/P SPECT/CT hybrid imaging. Sixty-nine subjects, 55 with COPD (GOLD I–IV) and 14 apparently healthy smokers, were examined with V/P SPECT and LDCT hybrid imaging. Spirometry was used to verify COPD grade. Only one apparently healthy smoker and three COPD patients had a normal or nearly normal V/P SPECT. All other patients showed various degrees of airway obstruction, even when spirometry was normal. The same interpretation was reached on both modalities in 39% of the patients. LDCT made V/P SPECT interpretation more certain in 9% of the patients and, in 52%, LDCT provided additional diagnoses. LDCT better characterized the type of emphysema in 12 patients. In 19 cases, tumor-suspected changes were reported. Three of these 19 patients (ie, 4.3% of all subjects) were in the end confirmed to have lung cancer. The majority of LDCT findings were not regarded as clinically significant. V/P SPECT identified perfusion patterns consistent with decompensated left ventricular HF in 14 COPD patients. In 16 patients (23%), perfusion defects were observed. HF and perfusion defects were not recognized with LDCT. In COPD patients and long-time smokers, hybrid imaging had added value compared to V/P SPECT alone, by identifying patients with lung malignancy and more clearly identifying emphysema. V/P SPECT visualizes comorbidities to COPD not seen with LDCT, such as pulmonary embolism and left ventricular HF.

Jögi, Jonas; Markstad, Hanna; Tufvesson, Ellen; Bjermer, Leif; Bajc, Marika

2015-01-01

59

The added value of hybrid ventilation/perfusion SPECT/CT in patients with stable COPD or apparently healthy smokers. Cancer-suspected CT findings in the lungs are common when hybrid imaging is used.  

PubMed

Ventilation/perfusion (V/P) single-photon emission computed tomography (SPECT) is recognized as a diagnostic method with potential beyond the diagnosis of pulmonary embolism. V/P SPECT identifies functional impairment in diseases such as heart failure (HF), pneumonia, and chronic obstructive pulmonary disease (COPD). The development of hybrid SPECT/computed tomography (CT) systems, combining functional with morphological imaging through the addition of low-dose CT (LDCT), may be useful in COPD, as these patients are prone to lung cancer and other comorbidities. The aim of this study was to investigate the added value of LDCT among healthy smokers and patients with stable COPD, when examined with V/P SPECT/CT hybrid imaging. Sixty-nine subjects, 55 with COPD (GOLD I-IV) and 14 apparently healthy smokers, were examined with V/P SPECT and LDCT hybrid imaging. Spirometry was used to verify COPD grade. Only one apparently healthy smoker and three COPD patients had a normal or nearly normal V/P SPECT. All other patients showed various degrees of airway obstruction, even when spirometry was normal. The same interpretation was reached on both modalities in 39% of the patients. LDCT made V/P SPECT interpretation more certain in 9% of the patients and, in 52%, LDCT provided additional diagnoses. LDCT better characterized the type of emphysema in 12 patients. In 19 cases, tumor-suspected changes were reported. Three of these 19 patients (ie, 4.3% of all subjects) were in the end confirmed to have lung cancer. The majority of LDCT findings were not regarded as clinically significant. V/P SPECT identified perfusion patterns consistent with decompensated left ventricular HF in 14 COPD patients. In 16 patients (23%), perfusion defects were observed. HF and perfusion defects were not recognized with LDCT. In COPD patients and long-time smokers, hybrid imaging had added value compared to V/P SPECT alone, by identifying patients with lung malignancy and more clearly identifying emphysema. V/P SPECT visualizes comorbidities to COPD not seen with LDCT, such as pulmonary embolism and left ventricular HF. PMID:25565797

Jögi, Jonas; Markstad, Hanna; Tufvesson, Ellen; Bjermer, Leif; Bajc, Marika

2015-01-01

60

The isolated perfused lung.  

PubMed Central

The unique nonrespiratory functions of the lungs have become more apparent in recent years. The isolated perfused lung model offers many advantages over other methods for the study of pulmonary metabolism, xenobiotic disposition and the influence of interactions among agents of different physical forms. Detailed descriptions of the experimental preparation are elements in evaluating and comparing data from various sources but these are frequently neglected. A discussion and critique of the following elements are provided in this review in order to elucidate the typical problems one might encounter in evaluating data: perfusate type, perfusion method, construction materials, ventilation method, temperature control, surgical procedure, microbiological contamination and evaluation criteria of the preparation. Examples are given where the IPL method has been applied and suggestions are made for future research efforts. PMID:6383800

Niemeier, R W

1984-01-01

61

Anaesthesia ventilators.  

PubMed

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits. PMID:24249886

Jain, Rajnish K; Swaminathan, Srinivasan

2013-09-01

62

Earth's Energy Imbalance  

NASA Astrophysics Data System (ADS)

'Global warming' from increased greenhouse gases really refers to a global energy imbalance at the top-of-atmosphere (TOA). TOA measurements of radiation from space can track changes over time but lack absolute accuracy. An inventory of energy shows that over 90% of the imbalance is manifested as ocean heat content (OHC). Here we use ORAS4 ocean reanalysis data and other OHC estimates to compare the OHC rates of change with model-based estimates of TOA energy imbalance (from CCSM4), and with TOA satellite measurements for the year 2000 onwards. Most of the ocean-only OHC analyses extend to only 700 m depth, have large discrepancies among the rates of change of OHC, and do not resolve interannual variability adequately to capture ENSO and volcanic eruption effects. For the first time we show that ORAS4 OHC quantitatively agrees with the radiative forcing estimates of impacts of the 3 major volcanic eruptions since 1960 (Mt. Agung 1963, El Chichón 1982, and Mt. Pinatubo 1991). The natural variability of the energy imbalance is substantial from month-to-month associated with cloud and weather variations, and interannually mainly associated with ENSO, while the sun affects 15% of the climate change signal on decadal timescales. All estimates (OHC and TOA) show that over the past decade the energy imbalance ranges between about 0.5 and 1 W m-2. By using the full-depth ocean, there is a better overall accounting for energy, but discrepancies remain at interannual timescales between OHC and TOA radiation measurements, notably in 2008-09.

Trenberth, K. E.; Fasullo, J.

2013-12-01

63

Fixed sagittal plane imbalance.  

PubMed

Study Design?Literature review. Objective?To discuss the evaluation and management of fixed sagittal plane imbalance. Methods?A comprehensive literature review was performed on the preoperative evaluation of patients with sagittal plane malalignment, as well as the surgical strategies to address sagittal plane deformity. Results?Sagittal plane imbalance is often caused by de novo scoliosis or iatrogenic flat back deformity. Understanding the etiology and magnitude of sagittal malalignment is crucial in realignment planning. Objective parameters have been developed to guide surgeons in determining how much correction is needed to achieve favorable outcomes. Currently, the goals of surgery are to restore a sagittal vertical axis?imbalance varies according to the etiology, location, and severity of the deformity. Fixed sagittal malalignment often requires complex reconstructive procedures that include osteotomy correction. Reestablishing harmonious spinopelvic alignment is associated with significant improvement in health-related quality-of-life outcome measures and patient satisfaction. PMID:25396111

Savage, Jason W; Patel, Alpesh A

2014-12-01

64

Krypton-81m ventilation scanning: acute respiratory disease  

SciTech Connect

From experience with 700 patients undergoing ventilation and perfusion lung scanning with krypton-81m/technetium-99m technique, 34 patients suffering from nonembolic acute respiratory disease were selected for review. In 16 patients with pneumonia, all had defects of ventilation corresponding to, or larger than, the radiologic consolidation. In 13 patients there was some preservation of perfusion in the consolidated region. In two of the three patients with matched defects, the pneumonia was of long standing. In seven patients with collapse or atelectasis and in 11 patients with acute reversible bronchial obstruction and normal volume lungs, a similar pattern or ventillation and perfusion was observed.

Lavender, J.P. (Royal Postgraduate Medical School, London, England); Irving, H.; Armstrong, J.D. II

1981-02-01

65

Unusual appearance of thromboembolism on perfusion lung imaging.  

PubMed

A 46-year-old woman with advanced ovarian carcinoma had progressive dyspnea and was evaluated with ventilation and perfusion lung imaging. A characteristic pattern of multiple branching perfusion defects of a segmental nature on the perfusion scan suggested tumor microembolism and lymphangitic carcinomatosis. However, in this case, this pattern was associated with pulmonary thromboembolism and was documented by the post mortem examination. Pulmonary thromboembolism should be included among the differential diagnoses in a patient with clinical symptoms and a perfusion scan that reveals multiple branching perfusion defects. PMID:10478745

Shadan, S; Challa, S; Hawkins, R A

1999-09-01

66

Ex vivo lung perfusion  

PubMed Central

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

Machuca, Tiago N.

2014-01-01

67

Ventilation Model  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. The purposes of Revision 01 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post-closure thermal models (Section 6.6). (3) To satisfy the remainder of KTI agreement TEF 2.07 (Reamer and Williams 2001b). Specifically to provide the results of post-test ANSYS modeling of the Atlas Facility forced convection tests (Section 7.1.2). This portion of the model report also serves as a validation exercise per AP-SIII.10Q, Models, for the ANSYS ventilation model. (4) To further satisfy KTI agreements RDTME 3.01 and 3.14 (Reamer and Williams 2001a) by providing the source documentation referred to in the KTI Letter Report, ''Effect of Forced Ventilation on Thermal-Hydrologic Conditions in the Engineered Barrier System and Near Field Environment'' (Williams 2002). Specifically to provide the results of the MULTIFLUX model which simulates the coupled processes of heat and mass transfer in and around waste emplacement drifts during periods of forced ventilation. This portion of the model report is presented as an Alternative Conceptual Model with a numerical application, and also provides corroborative results used for model validation purposes (Section 6.3 and 6.4).

V. Chipman

2002-10-05

68

Perfusion lung scan: an aid in detection of lymphangitic carcinomatosis  

SciTech Connect

Lymphangitic carcinomatosis is usually a late manifestation of metastatic disease. The patient usually presents with cough or dyspnea, and the chest radiograph is often nondiagnostic. Two patients are presented who developed symptoms while on adjuvant chemotherapy. Both had abnormal perfusion lung scans. One had matching ventilation defects; the other a normal ventilation study. Biopsy revealed metastatic carcinoma; in one case tumor was seen in both the pulmonary lymphatics and arterioles; in technique which can speed diagnosis and institution of therapy in lymphangitic carcinomatosis.

Bates, S.E.; Tranum, B.L.

1982-07-15

69

Ventilation shaft to increase effectiveness of natural ventilation.  

E-print Network

??Ventilation shafts can aid natural ventilation in buildings. Natural ventilation provides ventilation for occupants that can provide thermal comfort conditions. This study attempts to increase… (more)

Nagory, Abhay

2012-01-01

70

Microfluidic perfusion culture.  

PubMed

Microfluidic perfusion culture is a novel technique to culture animal cells in a small-scale microchamber with medium perfusion. Polydimethylsiloxane (PDMS) is the most popular material to fabricate a microfluidic perfusion culture chip. Photolithography and replica molding techniques are generally used for fabrication of a microfluidic perfusion culture chip. Pressure-driven perfusion culture system is convenient technique to carry out the perfusion culture of animal cells in a microfluidic device. Here, we describe a general theory on microfluid network design, microfabrication technique, and experimental technique for pressure-driven perfusion culture in an 8 × 8 microchamber array on a glass slide-sized microchip made out of PDMS. PMID:24297421

Hattori, Koji; Sugiura, Shinji; Kanamori, Toshiyuki

2014-01-01

71

Ventilator-driven xenon ventilation studies  

SciTech Connect

A modification of a common commerical Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilator rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

1984-07-01

72

Pulmonary blood flow distribution in sheep: effects of anesthesia, mechanical ventilation, and change in posture  

NASA Technical Reports Server (NTRS)

BACKGROUND: Recent studies providing high-resolution images of pulmonary perfusion have questioned the classical zone model of pulmonary perfusion. Hence the present work was undertaken to provide detailed maps of regional pulmonary perfusion to examine the influence of anesthesia, mechanical ventilation, and posture. METHODS: Pulmonary perfusion was analyzed with intravenous fluorescent microspheres (15 microm) in six sheep studied in four conditions: prone and awake, prone with pentobarbital-anesthesia and breathing spontaneously, prone with anesthesia and mechanical ventilation, and supine with anesthesia and mechanical ventilation. Lungs were air dried at total lung capacity and sectioned into approximately 1,100 pieces (about 2 cm3) per animal. The pieces were weighed and assigned spatial coordinates. Fluorescence was read on a spectrophotometer, and signals were corrected for piece weight and normalized to mean flow. Pulmonary blood flow heterogeneity was assessed using the coefficient of variation of flow data. RESULTS: Pentobarbital anesthesia and mechanical ventilation did not influence perfusion heterogeneity, but heterogeneity increased when the animals were in the supine posture (P < 0.01). Gravitational flow gradients were absent in the prone position but present in the supine (P < 0.001 compared with zero). Pulmonary perfusion was distributed with a hilar-to-peripheral gradient in animals breathing spontaneously (P < 0.05). CONCLUSIONS: The influence of pentobarbital anesthesia and mechanical ventilation on pulmonary perfusion heterogeneity is small compared with the effect of changes in posture. Analysis of flow gradients indicate that gravity plays a small role in determining pulmonary blood flow distribution.

Walther, S. M.; Domino, K. B.; Glenny, R. W.; Hlastala, M. P.

1997-01-01

73

Oxidative Imbalance and Anxiety Disorders  

PubMed Central

The oxidative imbalance appears to have an important role in anxiety development. Studies in both humans and animals have shown a strong correlation between anxiety and oxidative stress. In humans, for example, the increased malondialdehyde levels and discrepancies in antioxidant enzymes in erythrocytes have been observed. In animals, several studies also show that anxiety-like behavior is related to the oxidative imbalance. Moreover, anxiety-like behavior can be caused by pharmacological-induced oxidative stress. Studies using knockout or overexpression of antioxidant enzymes have shown a relationship between anxiety-like behavior and oxidative stress. Related factors of oxidative stress that could influence anxious behavior are revised, including impaired function of different mitochondrial proteins, inflammatory cytokines, and neurotrophic factors. It has been suggested that a therapy specifically focus in reducing reactive species production may have a beneficial effect in reducing anxiety. However, the neurobiological pathways underlying the effect of oxidative stress on anxiety symptoms are not fully comprehended. The challenge now is to identify the oxidative stress mechanisms likely to be involved in the induction of anxiety symptoms. Understanding these pathways could help to clarify the neurobiology of the anxiety disorder and provide tools for new discovery in therapies and preventive strategies. PMID:24669212

R, Krolow; D. M, Arcego; C, Noschang; S. N, Weis; C, Dalmaz

2014-01-01

74

Estimation of Lung Ventilation  

NASA Astrophysics Data System (ADS)

Since the primary function of the lung is gas exchange, ventilation can be interpreted as an index of lung function in addition to perfusion. Injury and disease processes can alter lung function on a global and/or a local level. MDCT can be used to acquire multiple static breath-hold CT images of the lung taken at different lung volumes, or with proper respiratory control, 4DCT images of the lung reconstructed at different respiratory phases. Image registration can be applied to this data to estimate a deformation field that transforms the lung from one volume configuration to the other. This deformation field can be analyzed to estimate local lung tissue expansion, calculate voxel-by-voxel intensity change, and make biomechanical measurements. The physiologic significance of the registration-based measures of respiratory function can be established by comparing to more conventional measurements, such as nuclear medicine or contrast wash-in/wash-out studies with CT or MR. An important emerging application of these methods is the detection of pulmonary function change in subjects undergoing radiation therapy (RT) for lung cancer. During RT, treatment is commonly limited to sub-therapeutic doses due to unintended toxicity to normal lung tissue. Measurement of pulmonary function may be useful as a planning tool during RT planning, may be useful for tracking the progression of toxicity to nearby normal tissue during RT, and can be used to evaluate the effectiveness of a treatment post-therapy. This chapter reviews the basic measures to estimate regional ventilation from image registration of CT images, the comparison of them to the existing golden standard and the application in radiation therapy.

Ding, Kai; Cao, Kunlin; Du, Kaifang; Amelon, Ryan; Christensen, Gary E.; Raghavan, Madhavan; Reinhardt, Joseph M.

75

Mechanical ventilator - infants  

MedlinePLUS

Ventilator - infants; Respirator - infants ... WHY IS A MECHANICAL VENTILATOR USED? A ventilator is used to provide breathing support for ill or immature babies. Sick or premature babies are often ...

76

Crankcase ventilator  

SciTech Connect

This patent describes a crankcase ventilator. It comprises: a conduct adapted to be attached to crankcase and a suction means for drawing air containing vapors from the crankcase through the conduit, a temperature sensitive element adapted to be placed in thermal contact with the crankcase, means for continuously varying the rate at which the suction means draws the air containing vapors from the crankcase according to temperature, and means connecting the varying means to the temperature sensitive element for causing the suction means to draw a greater volume of air from the crankcase when the crankcase is hot than when the crankcase is cold.

Pickering, J.J.

1989-11-14

77

What is Imbalance of Nature?  

NASA Astrophysics Data System (ADS)

The Mother Nature is imbalanced at all. The Mother Nature is every moment new, never returns to previous condition. The gravity and magnetosphere are changeable and imbalanced. The Sun is changeable and imbalanced. The climate is changeable and imbalanced. The atmosphere is changeable and imbalanced. The ocean is changeable and imbalanced. The crust and deep interior are changeable and imbalanced. The cryosphere is changeable and imbalanced. The life is simultaneously as the creator and the result of the imbalance of Nature. The people society is changeable and imbalanced. All chemical, physical, social, and other phenomenons are changeable and imbalanced. It's just that each phenomenon of the Mother Nature has some personal time-scale: one change in a nanosecond, and looks like for us as instable, i.e. imbalanced; while others change over millions years and, therefore, to us looks like not changeable, i.e. balanced. The scientists who are studying the Nature have convinced that the real balance never exist in Nature. Sometimes we can see something that is stable, i.e. balanced. But on closer study it appears that we are witnessing is not eternal rest and balance, it is not eternal STOP, but it is the perpetual motion, changing, there are a lot of imbalances. The balance it can be some result of the temporary mutual compensation the imbalanced processes in opposite directions. The balance it can be also some result of the inaccurate measurement, misunderstanding of conception or even request from bosses. But if we start use more accurate measurements, improve the models and not fear the bosses, than usually we got some new details. These new details show thet under the balanced visibility in really is hiding the interaction of many imbalanced processes of different directions. The balanced logic usually answers to question: What is it? The balanced answers are approximate and it will be updated many times during the development of science and practice. The imbalanced logic usually answers to question: How and why it is happened in details? The imbalanced answers are approximate also, and they will also be updated many times during the development of science and practice. But the imbalanced logic allows us to overcome of the inertia of the balanced logic and much closer come up to understanding the essence of Nature. We try to answer the central question of humanity: How to get calm, i.e. balanced life if the everything around us is imbalanced, the people themselves are restless and not eternal? The study of the Imbalance of Nature is multi-disciplinary because Nature is one. It is our main advantage.

Kontar, V. A.

2012-12-01

78

Gas exchange and intrapulmonary distribution of ventilation during continuous-flow ventilation  

SciTech Connect

In 12 anesthetized paralyzed dogs, pulmonary gas exchange and intrapulmonary inspired gas distribution were compared between continuous-flow ventilation (CFV) and conventional mechanical ventilation (CMV). Nine dogs were studied while they were lying supine, and three dogs were studied while they were lying prone. A single-lumen catheter for tracheal insufflation and a double-lumen catheter for bilateral endobronchial insufflation (inspired O2 fraction = 0.4; inspired minute ventilation = 1.7 +/- 0.3 (SD) 1.kg-1.min-1) were evaluated. Intrapulmonary gas distribution was assessed from regional 133Xe clearances. In dogs lying supine, CO2 elimination was more efficient with endobronchial insufflation than with tracheal insufflation, but the alveolar-arterial O2 partial pressure difference was larger during CFV than during CMV, regardless of the type of insufflation. By contrast, endobronchial insufflation maintained both arterial PCO2 and alveolar-arterial O2 partial pressure difference at significantly lower levels in dogs lying prone than in dogs lying supine. In dogs lying supine, the dependent lung was preferentially ventilated during CMV but not during CFV. In dogs lying prone, gas distribution was uniform with both modes of ventilation. The alveolar-arterial O2 partial pressure difference during CFV in dogs lying supine was negatively correlated with the reduced ventilation of the dependent lung, which suggests that increased ventilation-perfusion mismatching was responsible for the increase in alveolar-arterial O2 partial pressure difference. The more efficient oxygenation during CFV in dogs lying prone suggests a more efficient matching of ventilation to perfusion, presumably because the distribution of blood flow is also nearly uniform.

Vettermann, J.; Brusasco, V.; Rehder, K.

1988-05-01

79

Immune imbalance in cancer patients.  

PubMed

The immune status of the tumor-bearing patient remains poorly defined. In various solid-tumor-bearing patients, we demonstrated the absence of ADCC modifications in the patient in relapse or in evolution. These same patients presented a significant increase in immune complexes when compared with patients in remission. Furthermore, we noted a decreased NK activity, a decreased number of ARFC, corresponding to a helper T cell subpopulation, and a corollary increase in T-dependent suppressor activity. These results, on the whole, suggest an immune imbalance and that the helper cell-suppressor cell ratio should be investigated in greater depth within the context of the immune response in the cancer patient. PMID:6453412

Serrou, B; Gauci, L; Caraux, J; Cupissol, D; Thierry, C; Esteve, C

1980-01-01

80

Ventilator-driven xenon ventilation studies  

SciTech Connect

A modification of a common commercial Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilatory rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

1984-07-01

81

Meeting Residential Ventilation Standards  

E-print Network

LBNL 4591E Meeting Residential Ventilation Standards Through Dynamic Control of Ventilation Systems ventilation standards, including American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) Standard 62.2, specify continuous operation of a defined mechanical ventilation system to provide

82

Active correction of mass imbalance for a precise rotor  

Microsoft Academic Search

An active mass imbalance correction method for a precision rotor that is formulated iteratively is introduced. Since mass imbalance of a precise rotor has been one of the critical volume production issues for a long time especially in the data storage industry, various imbalance correction methods are developed and successfully implemented. Nevertheless, volume manufacturing tolerance of the mass imbalance has

J. K. Lee; Y. S. Ihn; J. C. Koo; Dongho Oh; Ho Sung Lee

2009-01-01

83

Active Correction of Dynamic Mass Imbalance for a Precise Rotor  

Microsoft Academic Search

An adaptive mass imbalance correction method for a precision rotor that is formulated in frequency domain is introduced. Various imbalance correction methods are developed and successfully implemented since mass imbalance of a precise rotor has been one of the critical volume production issues for decades, especially in the data storage industry. Meanwhile the volume manufacturing tolerance of the mass imbalance

Y. S. Ihn; J. K. Lee; D. H. Oh; H. S. Lee; J. C. Koo

2009-01-01

84

VENTILATION MODEL REPORT  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their postclosure analyses.

V. Chipman

2002-10-31

85

Home Ventilator Guide  

MedlinePLUS

... is ventilation? respiration? Ventilation is the process of moving air in and out of the lungs. Respiration ... when I'm talking and using the vent. Moving about in bed does not cause alarms as ...

86

Perfusion lung scan: an aid in detection of lymphangitic carcinomatosis  

SciTech Connect

Lymphangitic carcinomatosis is usually a late manifestation of metastatic disease. The patient usually presents with cough or dyspnea, and the chest radiograph is often nondiagnostic. Two patients are presented who developed symptoms while on adjuvant chemotherapy. Both had abnormal perfusion lung scans. One had matching ventilation defects; the other a normal ventilation study. Biopsy revealed metastatic carcinoma; in one case tumor was seen in both the pulmonary lymphatics and arterioles; in the other, tumor was identified but the site could not be specified. The radionuclide lung scan is a technique which can speed diagnosis and institution of therapy in lymphangitic carcinomatosis.

Bates, S.E.; Tranum, B.L.

1982-07-15

87

DEMAND CONTROLLED VENTILATION AND CLASSROOM VENTILATION  

SciTech Connect

This document summarizes a research effort on demand controlled ventilation and classroom ventilation. The research on demand controlled ventilation included field studies and building energy modeling. Major findings included: ? The single-location carbon dioxide sensors widely used for demand controlled ventilation frequently have large errors and will fail to effectively control ventilation rates (VRs).? Multi-location carbon dioxide measurement systems with more expensive sensors connected to multi-location sampling systems may measure carbon dioxide more accurately.? Currently-available optical people counting systems work well much of the time but have large counting errors in some situations. ? In meeting rooms, measurements of carbon dioxide at return-air grilles appear to be a better choice than wall-mounted sensors.? In California, demand controlled ventilation in general office spaces is projected to save significant energy and be cost effective only if typical VRs without demand controlled ventilation are very high relative to VRs in codes. Based on the research, several recommendations were developed for demand controlled ventilation specifications in the California Title 24 Building Energy Efficiency Standards.The research on classroom ventilation collected data over two years on California elementary school classrooms to investigate associations between VRs and student illness absence (IA). Major findings included: ? Median classroom VRs in all studied climate zones were below the California guideline, and 40percent lower in portable than permanent buildings.? Overall, one additional L/s per person of VR was associated with 1.6percent less IA. ? Increasing average VRs in California K-12 classrooms from the current average to the required level is estimated to decrease IA by 3.4percent, increasing State attendance-based funding to school districts by $33M, with $6.2 M in increased energy costs. Further VR increases would provide additional benefits.? Confirming these findings in intervention studies is recommended. ? Energy costs of heating/cooling unoccupied classrooms statewide are modest, but a large portion occurs in relatively few classrooms.

Fisk, William J.; Mendell, Mark J.; Davies, Molly; Eliseeva, Ekaterina; Faulkner, David; Hong, Tienzen; Sullivan, Douglas P.

2014-01-06

88

Abdominal Perfusion Computed Tomography  

PubMed Central

The purpose of this article is to provide an up to date review on the spectrum of applications of perfusion computed tomography (CT) in the abdomen. New imaging techniques have been developed with the objective of obtaining a structural and functional analysis of different organs. Recently, perfusion CT has aroused the interest of many researchers who are studying the applicability of imaging modalities in the evaluation of abdominal organs and diseases. Per-fusion CT enables fast, non-invasive imaging of the tumor vascular physiology. Moreover, it can act as an in vivo biomarker of tumor-related angiogenesis.

Ogul, Hayri; Bayraktutan, Ummugulsum; Kizrak, Yesim; Pirimoglu, Berhan; Yuceler, Zeynep; Sagsoz, M. Erdem; Yilmaz, Omer; Aydinli, Bulent; Ozturk, Gurkan; Kantarci, Mecit

2013-01-01

89

Global imbalances, saving glut and investment strike  

Microsoft Academic Search

The present state of the global economy is characterised by persistent and increasingly polarised current account imbalances, in a context of historically low long-term interest rates, which stand below the equilibrium levels proxied by potential growth and trend inflation. A comprehensive analysis by Ben Bernanke1 attributes those two phenomena to one common cause: a global saving glut outside the United

G. Moëc; L. Frey

2006-01-01

90

Computed Tomography Studies of Lung Ventilation and Perfusion  

Microsoft Academic Search

With the emergence of multidetector-row computed tomography (CT) it is now possible to image both structure and function via use of a single imaging modality. Breath-hold spiral CT provides detail of the airway and vascular trees along with texture reflective of the state of the lung parenchyma. Use of stable xenon gas wash- in and\\/or wash-out methods using an axial

Eric A. Hoffman; Deokiee Chon

2005-01-01

91

Protective garment ventilation system  

NASA Technical Reports Server (NTRS)

A method and apparatus for ventilating a protective garment, space suit system, and/or pressure suits to maintain a comfortable and nontoxic atmosphere within is described. The direction of flow of a ventilating and purging gas in portions of the garment may be reversed in order to compensate for changes in environment and activity of the wearer. The entire flow of the ventilating gas can also be directed first to the helmet associated with the garment.

Lang, R. (inventor)

1970-01-01

92

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY ...  

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

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

93

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS ...  

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

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION. - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

94

Ventilator for ignition distributor  

SciTech Connect

A ventilator for an ignition distributor is described in which bent air holes are provided in a housing of the distributor, and ventilation of the distributor is performed by utilizing rotation of air in the distributor caused by rotation of a distribution rotor. The improvement is that the angle of bend of each bent air hole is an obtuse angle and among the air holes, a cross-sectional area of a each ventilation intake port is larger than that of each ventilation exhaust port.

Arano, I.; Kokubun, T.

1988-12-27

95

Drillstring Component Mass Imbalance: A Major Source of Downhole Vibrations  

Microsoft Academic Search

A study consisting of surface and downhole field experiments, theoretical analysis, and numerical modeling has shown that mass imbalance of drillstring components is a major source of downhole lateral vibrations. Factors that contribute to imbalance include bore misalignment, initial curvature, and gradual wear during service. Field experiments were conducted on the surface to quantify drillstring component mass imbalance for modeling

M. W. Dykstra; D. C. K. Chen; T. M. Warren; J. J. Azar

1996-01-01

96

Effect of Ventilation Strategies on  

E-print Network

1 Effect of Ventilation Strategies on Residential Ozone Levels Iain S. Walker ventilation used to reduce concentrations of indoor-generated pollutants. When assessing the effect of deliberate ventilation on occupant health one should consider not only

97

Ventilator Associated Pneumonia (VAP)  

E-print Network

Ventilator Associated Pneumonia (VAP) Prevention in a CVSICU ­ A CUSP based framework Ventilator Associated Pneumonia (VAP) is a serious hospital acquired condition that develops within 72 hours- associated pneumonia in intensive care: Impact of implementing a care bundle*. Critical Care Medicine, 39

Connor, Ed

98

Prevention of ventilator-induced lung edema by inhalation of nanoparticles releasing ruthenium red.  

PubMed

The acute respiratory distress syndrome (ARDS), a devastating lung disease that has no cure, is exacerbated by life-supportive mechanical ventilation that worsens lung edema and inflammation through the syndrome of ventilator-induced lung injury. Recently, the membrane ion channel transient receptor potential vanilloid 4 (TRPV4) on alveolar macrophages was shown to mediate murine lung vascular permeability induced by high-pressure mechanical ventilation. The objective of this study was to determine whether inhalation of nanoparticles (NPs) containing the TRPV4 inhibitor ruthenium red (RR) prevents ventilator-induced lung edema in mice. Poly-lactic-co-glycolic acid NPs containing RR were evaluated in vitro for their ability to block TRPV4-mediated calcium signaling in alveolar macrophages and capillary endothelial cells. Lungs from adult C57BL6 mice treated with nebulized NPs were then used in ex vivo ventilation perfusion experiments to assess the ability of the NPs to prevent high-pressure mechanical ventilation-induced lung edema. Poly-lactic-co-glycolic acid NPs (300 nm) released RR for 150 hours in vitro, and blocked TRPV4-mediated calcium signaling in cells up to 7 days after phagocytosis. Inhaled NPs deposited in alveoli of spontaneously breathing mice were rapidly phagocytosed by alveolar macrophages, and blocked increased vascular permeability from high-pressure mechanical ventilation for 72 hours in ex vivo ventilation perfusion experiments. These data offer proof of principle that inhalation of NPs containing a TRPV4 inhibitor prevents ventilator damage for several days, and imply that this novel drug delivery strategy could be used to target alveolar macrophages in patients at risk of ventilator-induced lung injury before initiating mechanical ventilation. PMID:24405281

Jurek, Samuel C; Hirano-Kobayashi, Mariko; Chiang, Homer; Kohane, Daniel S; Matthews, Benjamin D

2014-06-01

99

The Global Imbalance of the Inanimate Nature  

NASA Astrophysics Data System (ADS)

The preservation laws serve is the general expression of balancing properties and stability in nature. The preservation laws, according to Noether's theorem, are displays of properties of uniformity and isotropy of space and time. So, in the most global representation, the imbalance of the Universe assumes presence of some large-scale non-uniformity in it. The scale of such non-uniformity may form the basis for balance and imbalance correlation in the nature as a whole. This heterogeneity may lead to global infringement of laws of preservation, such as laws of preservation of an impulse, the impulse and the moment of energy. So, the most global imbalance of the inanimate nature may be connected with existence of large-scale fluctuations of properties of the Universe matter. It is possible to think about existence of such imbalance with presence of the allocated areas and directions on celestial sphere. Now most of interest in a science is represented by some types of global anisotropy. First, it is spatial anisotropy of cosmic microwave background. It depends of direction on celestial sphere, including formation of the allocated directions, and also "hot" and "cold" spots. Secondly, it is anisotropy of substance's density, concerning clusters and super clusters of galaxies. It is known as a large-scale structure of the Universe. This kind of anisotropy is connected with imbalance between distributions of radiated substance and observable emptiness. The geometry of this kind of imbalance is that the shining matter forms "cellular", "sheet" or "filaments" structure, forming the cells, filled with visible "voids". Thirdly, it is the hypothetical anisotropy connected with prospective dependence of speed of expansion of the Universe with direction on celestial sphere, and also with time. The relative size for this speed is known as Hubble's parameter. The told testifies about actuality of systematization, and also revelation of an interconnection and mutual conditionality of various kinds of global anisotropy of the Universe. So, astro- and photometric characteristics of various types of remote quasi-stellar objects may be used. Modern catalogues contain more than one million quasars. If the property of quasars on the average is invariable in various directions and during the various moments of time, anisotropy of average luminosity received with the calculations is a consequence of anisotropy of properties of expansion of the Universe. For example, if in any direction average settlement luminosity of quasars is underestimated, it is necessary to considering as consequence of the raised speed of expansion of the Universe in this direction. Thus it is possible to establish both speed, and acceleration of expansion of the Universe in these directions during the various moments of time on the basis of difference in average luminosity of the quasars observed in various directions of the Universe and on various removals from the ground observer. Comparison of the allocated places and directions in the Universe which are found out by means of the analysis of luminosity of quasars, and also distributions of temperature of a cosmic microwave background and distributions of density of system of voids and filaments in large-scale structure of the Universe will allow to think about global correlation of balance and imbalance in the scale of all inanimate nature as a whole.

Vargashkin, V. Y.

2013-12-01

100

Ventilating Air-Conditioner  

NASA Technical Reports Server (NTRS)

Air-conditioner provides ventilation designed to be used alone or incorporated into cooling or heating system operates efficiently only by recirculating stale air within building. Energy needed to operate overall ventilating cooling or heating system slightly greater than operating nonventilating cooling or heating system. Helps to preserve energy efficiency while satisfying need for increased forced ventilation to prevent accumulation of undesired gases like radon and formaldehyde. Provides fresh treated air to variety of confined spaces: hospital surgeries, laboratories, clean rooms, and printing shops and other places where solvents used. In mobile homes and portable classrooms, eliminates irritant chemicals exuded by carpets, panels, and other materials, ensuring healthy indoor environment for occupants.

Dinh, Khanh

1994-01-01

101

What Is a Ventilator?  

MedlinePLUS

... tor) is a machine that supports breathing. These machines mainly are used in hospitals. Ventilators: Get oxygen into the lungs. Remove carbon dioxide from the body. (Carbon dioxide is a waste gas that can ...

102

Why We Ventilate  

SciTech Connect

It is widely accepted that ventilation is critical for providing good indoor air quality (IAQ) in homes. However, the definition of"good" IAQ, and the most effective, energy efficient methods for delivering it are still matters of research and debate. This paper presents the results of work done at the Lawrence Berkeley National Lab to identify the air pollutants that drive the need for ventilation as part of a larger effort to develop a health-based ventilation standard. First, we present results of a hazard analysis that identified the pollutants that most commonly reach concentrations in homes that exceed health-based standards or guidelines for chronic or acute exposures. Second, we present results of an impact assessment that identified the air pollutants that cause the most harm to the U.S. population from chronic inhalation in residences. Lastly, we describe the implications of our findings for developing effective ventilation standards.

Logue, Jennifer M.; Sherman, Max H.; Price, Phil N.; Singer, Brett C.

2011-09-01

103

The perfused swine uterus model: long-term perfusion  

PubMed Central

Background It has previously been shown that the viability of swine uteri can be maintained within the physiological range in an open perfusion model for up to 8 hours. The aim of this study was to assess medium- to long-term perfusion of swine uteri using a modified Krebs–Ringer bicarbonate buffer solution (KRBB) in the established open perfusion model. Methods In an experimental study at an infertility institute, 30 swine uteri were perfused: group 1: n?=?11, KRBB; group 2: n?=?8, modified KRBB with drainage of perfusate supernatant; group 3: n?=?11, modified KRBB with drainage of perfusate every 2 h and substitution with fresh medium. Modified and conventional KRBB were compared with regard to survival and contraction parameters: intrauterine pressure (IUP), area under the curve (AUC), and frequency of contractions (F). Results Modified KRBB showed significantly higher IUP, AUC, and F values than perfusion with conventional KRBB. In group 3, the organ survival time of up to 17 h, with a 98% rate of effective contraction time, differed significantly from group 1 (P?perfusate substitution improves the open model for perfusion of swine uteri with regard to survival time and quality of contraction parameters. This model can be used for medium- to long-term perfusion of swine uteri, allowing further metabolic ex vivo studies in a cost-effective way and with little logistic effort. PMID:23241226

2012-01-01

104

Conventional mechanical ventilation.  

PubMed

The provision of mechanical ventilation for the support of infants and children with respiratory failure or insufficiency is one of the most common techniques that are performed in the Pediatric Intensive Care Unit (PICU). Despite its widespread application in the PICUs of the 21st century, before the 1930s, respiratory failure was uniformly fatal due to the lack of equipment and techniques for airway management and ventilatory support. The operating rooms of the 1950s and 1960s provided the arena for the development of the manual skills and the refinement of the equipment needed for airway management, which subsequently led to the more widespread use of endotracheal intubation thereby ushering in the era of positive pressure ventilation. Although there seems to be an ever increasing complexity in the techniques of mechanical ventilation, its successful use in the PICU should be guided by the basic principles of gas exchange and the physiology of respiratory function. With an understanding of these key concepts and the use of basic concepts of mechanical ventilation, this technique can be successfully applied in both the PICU and the operating room. This article reviews the basic physiology of gas exchange, principles of pulmonary physiology, and the concepts of mechanical ventilation to provide an overview of the knowledge required for the provision of conventional mechanical ventilation in various clinical arenas. PMID:20927268

Tobias, Joseph D

2010-05-01

105

[Vestibulospinal reactions in cervicogenic disequilibrium. Cervicogenic imbalance].  

PubMed

A functional cervical spine disorder is often the cause for persistent vertigo, which can last months or several years. The existence of cervical vertigo is not generally recognized, mainly because an objectivation of the cervical nystagmus is not easily understood by many examiners. In this study we examine additional parameters, which underline the diagnosis of cervical imbalance. The anamnestic statement of staggering refers to a disturbance of the vestibulospinal reactions. In 67 patients in which cervical imbalance was suspected the vestibulospinal reactions were monitored directly before and after manual therapy of the cervical spine. The cranio-corpo-graphie (CCG) and the posturography were used to monitor the results. A highly significant improvement of pathological vestibulospinal reactions was seen after chiropractic manipulation of the spine. These results show that a functional disorder of the cervical vertebrae influences the vestibulospinal reactions. The pathological deficit of the vestibulospinal reactions is not solely a phenomenon of peripheric labyrinth malfunction, failure in the brainstem or in the area of the cerebellum ("brain stem staggering"), but can also be viewed nearly regularly by cervical disturbance of the equilibrium. The results of the treatment can be observed within a few hours. PMID:10810676

Hülse, M; Hölzl, M

2000-04-01

106

A Resonant Synchronous Vibration Based Approach for Rotor Imbalance Detection  

NASA Technical Reports Server (NTRS)

This paper presents a methodology of detecting rotor imbalances, such as mass imbalance and crack-induced imbalance, using shaft synchronous vibrations. An iterative scheme is developed to identify parameters from measured synchronous vibration data. A detection system is integrated by using state-of-the-art commercial analysis equipment. A laboratory rotor test rig is used to verify the system integration and algorithm validation. A real engine test has been carried out and the results are reported.

Luo, Huangeng; Rodriquez, Hector; Hallman, Darren; Lewicki, David G.

2006-01-01

107

Measuring continuous baseline covariate imbalances in clinical trial data  

PubMed Central

This paper presents and compares several methods of measuring continuous baseline covariate imbalance in clinical trial data. Simulations illustrate that though the t-test is an inappropriate method of assessing continuous baseline covariate imbalance, the test statistic itself is a robust measure in capturing imbalance in continuous covariate distributions. Guidelines to assess effects of imbalance on bias, type I error rate, and power for hypothesis test for treatment effect on continuous outcomes are presented, and the benefit of covariate-adjusted analysis (ANCOVA) is also illustrated. PMID:21865270

Ciolino, Jody D.; Martin, Renee’ H.; Zhao, Wenle; Hill, Michael D.; Jauch, Edward C.; Palesch, Yuko Y.

2014-01-01

108

Ventilator associated pneumonia  

PubMed Central

Hospital acquired or nosocomial infections continue to be an important cause of morbidity and mortality. The critically ill patient is at particular risk of developing intensive care unit acquired infection, with the lungs being especially vulnerable. Nosocomial bacterial pneumonia occurring after two days of mechanical ventilation is referred to as ventilator associated pneumonia, and is the most common nosocomial infection seen in the intensive care unit. Intubation of the trachea and mechanical ventilation is associated with a 7?fold to 21?fold increase in the incidence of pneumonia and up to 28% of patients receiving mechanical ventilation will develop this complication. Its development is associated with an attributable increase in morbidity and mortality. The establishment of an accurate diagnosis of ventilator associated pneumonia remains problematic and as yet there is still no accepted “gold standard” for diagnosis. The responsible pathogens vary according to case mix, local resistance patterns, and methodology of sampling. However, there is general agreement that rapid initiation of appropriate antimicrobial therapy improves outcome. PMID:16517798

Hunter, J D

2006-01-01

109

Clinical Impact of Proximal Autosomal Imbalances  

PubMed Central

Centromere-near gain of copy number can be induced by intra- or inter-chromosomal rearrangements or by the presence of a small supernumerary marker chromosome (sSMC). Interestingly, partial trisomy to hexasomy of euchromatic material may be present in clinically healthy or affected individuals, depending on origin and size of chromosomal material involved. Here we report the known minimal sizes of all centromere-near, i.e., proximal auto-somal regions in humans, which are tolerated; over 100 Mb of coding DNA are comprised in these regions. Additionally, we have summarized the typical symptoms for nine proximal autosomal regions including genes obviously sensitive to copy numbers. Overall, studying the carriers of specific chromosomal imbalances using genomics-based medicine, combined with single cell analysis can provide the genotype-phenotype correlations and can also give hints where copy-number-sensitive genes are located in the human genome. PMID:24052727

Hamid, AB; Weise, A; Voigt, M; Bucksch, M; Kosyakova, N; Liehr, T; Klein, E

2012-01-01

110

Perfusion Based Cell Culture Chips  

NASA Astrophysics Data System (ADS)

Performing cell culture in miniaturized perfusion chambers gives possibilities to experiment with cells under near in vivo like conditions. In contrast to traditional batch cultures, miniaturized perfusion systems provide precise control of medium composition, long term unattended cultures and tissue like structuring of the cultures. However, as this chapter illustrates, many issues remain to be identified regarding perfusion cell culture such as design, material choice and how to use these systems before they will be widespread amongst biomedical researchers.

Heiskanen, A.; Emnéus, J.; Dufva, M.

111

Imbalance of Water as an Example of Fundamental Imbalance of Nature.  

NASA Astrophysics Data System (ADS)

Water is one of the main attributes of the world around us. Turning into ice or water vapor it controls a wide range of natural phenomena. It is one of the most moving substances of Earth and in it as in a mirror all imbalance of the Nature reflects. The laws that govern the water are above all the laws of classical physics, laws of motion and conservation. They determine an equilibrium state and out of it when the balance of forces, flows and energy is disturbed. Volcanic eruption, earthquake, tsunami, hurricane or tornado formation are the extreme form of imbalance of Nature. Unfortunately they are involved in it as a genetic feature. Mass and energy flows pervade the natural world. The structure of the space makes them come into conflict. Internal stress increase, there is an imbalance resulting in the fast, catastrophic events. Whether it is possible to understand the reasons of similar imbalance and to find its critical conditions? The water in their states shows the most striking examples of imbalance of Nature. If the equilibrium of forces and flows is disturbed the nature of movement can fundamentally change. The dependence of the total flux I flowing through the structure of the pressure drop ?p causing this flow can serve as an important informative characteristic for the imbalance phenomena connected with water. This «flow - forcing» characteristic I(?p) qualitatively changes its form with changes of so-called bifurcation parameter. From monotonous it can become S- or N-shaped. The approach to the analysis of Nature imbalance phenomenon can be illustrated by geyser eruption mechanism which is theoretically described in (Nechayev, 2012). One-dimensional motion of water flow in the geyser conduit obeys the Navier-Stokes equation. The influx of masses of water vapor due to water boiling in an underground chamber creates increasing overpressure. Bifurcation parameter is the volume of this chamber. There is a critical value of this volume (as compared with the volume of conduit) when the acceleration of the flow becomes positive and the eruption starts. The steady-state characteristic I (?p) can become S-shaped. The process of the volcanic eruption development is probably similar. In our opinion the main driving power of volcanic eruption is a contact of deep water-bearing layers to the magmatic chamber. Thermal energy of magma is transferred to the overpressure of superheated water vapor in some porous zone which is isolated from the surface. Bifurcation parameter is the volume of this vapor area. The magnitude of this volume determines the power of eruption, the velocities of lava and pyroclastic material. For the hurricanes too it is possible to find the analogous characteristic I (?p) (Nechayev, Solovyev, 2011). It can be the dependence of a full vertical air flow of horizontal pressure drop. Bifurcation parameter is the saturation mixing ratio of the moist air in the lower troposphere. Thus, despite all complexity of natural phenomena, it is possible to propose a generalized approach to the analysis of imbalance states of Nature taking into account the integral characteristics and corresponding bifurcation parameters.

Nechayev, A.

2012-12-01

112

Combating the Small Sample Class Imbalance Problem Using Feature Selection  

Microsoft Academic Search

The class imbalance problem is encountered in real-world applications of machine learning and results in a classifier's suboptimal performance. Researchers have rigorously studied the resampling, algorithms, and feature selection approaches to this problem. No systematic studies have been conducted to understand how well these methods combat the class imbalance problem and which of these methods best manage the different challenges

Michael Wasikowski; Xue-wen Chen

2010-01-01

113

Adjustment of Global Imbalances and Its Impact on China's Economy  

Microsoft Academic Search

The present paper discusses ways of adjusting the imbalances of the global economy and its impact on China's economy. The analysis in the paper shows that the cut of US fiscal deficits and the appreciation of the currencies of East Asia, including China's RMB, are necessary for a smooth adjustment of the global imbalances. The adjustments will have a positive

Jianhuai Shi

2006-01-01

114

Novel method for indirect sensing of hard disk drive imbalance  

Microsoft Academic Search

At present, hard disk drives (HDD) are balanced using external balancing machine after all components of HDD are assembled. Therefore, company's throughput is limited by number of available balancing machines. Besides, imbalance is measured only once after assembly, and for this reason there is no possibility to measure if there is any change in imbalance of HDD during its operation.

Branislav Hredzak; Guoxiao Guo

2004-01-01

115

New Method for Sensorless Measurement of Hard Disk Drives Imbalance  

Microsoft Academic Search

At present, hard disk drives (HDDs) are balanced using external balancing machine after all the components of the HDD are assembled. Therefore, company's throughput is limited by a number of available balancing machines. Besides, an imbalance is measured only once after assembly, and for this reason, there is no possibility to measure if there is any change in imbalance of

Branislav Hredzak; Guoxiao Guo; Jingliang Zhang

2006-01-01

116

Natural ventilation generates building form  

E-print Network

Natural ventilation is an efficient design strategy for thermal comfort in hot and humid climates. The building forms can generate different pressures and temperatures to induce natural ventilation. This thesis develops a ...

Chen, Shaw-Bing

1996-01-01

117

Innovative Energy Efficient Industrial Ventilation  

E-print Network

This paper was written to describe an innovative “on-demand” industrial ventilation system for woodworking, metalworking, food processing, pharmaceutical, chemical, and other industries. Having analyzed existing industrial ventilation in 130...

Litomisky, A.

2005-01-01

118

Ventilation flow: Submerged  

NASA Technical Reports Server (NTRS)

The ventilation system on a submarine is discussed. When the submarine is submerged. The ventilation system provides a conditioned atmosphere in the ship with complete isolation from the outside. A conditioned atmosphere includes not only filtration and temperature and humidity control, but also air purification (removal of potentially harmful quantities of impurities and comtaminants) and revitalization (addition of vital life support oxygen). Carbon dioxide removal, the oxygen system, air conditioning, carbon monoxide removal, hydrogen removal, and atmosphere monitoring systems are among the topics discussed.

Hutchinson, D.

1985-01-01

119

A review on wind driven ventilation techniques  

Microsoft Academic Search

Natural ventilation has gained prominence in recent times as a bespoke method of ventilating buildings. The two fundamental principles of natural ventilation are stack effect and wind driven ventilation. This paper reviews miscellaneous wind driven ventilation designs with respect to traditional means such as wind towers and more modern techniques including turbine ventilators and wind catchers. A distinction is made

Naghman Khan; Yuehong Su; Saffa B. Riffat

2008-01-01

120

Perfusion Bioreactor Module  

NASA Technical Reports Server (NTRS)

Perfusion bioreactor module, self-contained, closed-loop cell-culture system that operates in microgravity or on Earth. Equipment supports growth or long-term maintenance of cultures of human or other fragile cells for experiments in basic cell biology or process technology. Designed to support proliferation (initially at exponential rates of growth) of cells in complex growth medium and to maintain confluent cells in defined medium under conditions optimized to permit or encourage selected functions of cells, including secretion of products of cells into medium.

Morrison, Dennis R.

1990-01-01

121

3, 805826, 2006 Ventilation under  

E-print Network

OSD 3, 805­826, 2006 Ventilation under global warming A. Gnanadesikan et al. Title Page Abstract ocean ventilation change under global warming? A. Gnanadesikan 1 , J. L. Russell 2 , and F. Zeng 3 1­826, 2006 Ventilation under global warming A. Gnanadesikan et al. Title Page Abstract Introduction

Paris-Sud XI, Université de

122

The International Journal of Ventilation  

E-print Network

The International Journal of Ventilation Volume 12 Number 4 ISSN 1473 - 3315 March 2014 Contents A and Mróz T 391 #12;International Journal of Ventilation ISSN 1473-3315 Volume 12 No 4 March 2014 air quality and reducing energy required for heating, cooling, and ventilation. One application

California at Davis, University of

123

Space station ventilation study  

NASA Technical Reports Server (NTRS)

A ventilation system design and selection method which is applicable to any manned vehicle were developed. The method was used to generate design options for the NASA 33-foot diameter space station, all of which meet the ventilation system design requirements. System characteristics such as weight, volume, and power were normalized to dollar costs for each option. Total system costs for the various options ranged from a worst case $8 million to a group of four which were all approximately $2 million. A system design was then chosen from the $2 million group and is presented in detail. A ventilation system layout was designed for the MSFC space station mockup which provided comfortable, efficient ventilation of the mockup. A conditioned air distribution system design for the 14-foot diameter modular space station, using the same techniques, is also presented. The tradeoff study resulted in the selection of a system which costs $1.9 million, as compared to the alternate configuration which would have cost $2.6 million.

Colombo, G. V.; Allen, G. E.

1972-01-01

124

RESIDENTIAL VENTILATION STUDY  

EPA Science Inventory

This project evaluated the effectiveness, first costs and operational costs of various types of residential ventilation systems in three different climates in the U.S. The Agency, through its Energy Star Program, recommends that builders construct homes that are energy efficient ...

125

Perfusion MRI of Acute Stroke  

Microsoft Academic Search

Perfusion MRI allows evaluation of the hemodynamic status of acutely ischemic tissue and has greatly improved evaluation of acute stroke. The CBV abnormality correlates highly with the DWI abnormality, which is thought to represent the ischemic core. With proximal emboli, CBF and tissue transit time maps demonstrate the operational ischemic penumbra, additional tissue with altered perfusion that is at risk

Pamela W. Schaefer; William A. Copen; R. Gilberto González

126

Intracranial perfusion imaging with ultrasound.  

PubMed

In the last several years, great progress has been made in ultrasound perfusion imaging of the brain. Different approaches have been assessed and shown to be capable of the early detection of cerebral perfusion deficits in stroke patients. Real-time low-mechanical index imaging simplifies the acquisition of perfusion parameters and alleviates many of the previous imaging problems related to shadowing, uniplanar analysis, and temporal resolution. With the advent of this new, highly sensitive contrast-specific imaging technique, new possibilities of the real-time visualization of brain infarctions and cerebral hemorrhages have emerged. This review will detail the methodology of ultrasound perfusion imaging, discuss aspects of its safety and present the emerging clinical applications of brain perfusion assessment with ultrasound in acute stroke patients. © 2015 S. Karger AG, Basel. PMID:25531663

Meairs, Stephen; Kern, Rolf

2015-01-01

127

Conditions governing the pulmonary vascular response to ventilation hypoxia and hypoxaemia in the dog  

PubMed Central

1. Isolated lung lobes of the dog perfused through the pulmonary circulation only with atropinized autologous blood obtained by bleeding out the animal under general anaesthesia or following premedication with morphine hydrochloride were subjected to repetitive tests of ventilation hypoxia, the control and test gas mixtures containing similar concentrations of CO2. 2. The pulmonary vasomotor response to ventilation hypoxia depended upon the temperature of the perfusate and the time which had elapsed from the death of the animal to the start of perfusion, termed the `ischaemic period'. The higher blood temperatures and shorter ischaemic periods favoured a pulmonary vasopressor response to hypoxia, and the lower temperatures and longer ischaemic periods a vasodepressor response or an absence of response. 3. The vasopressor responses to hypoxia were associated with a rise in the pH (average, 0·09 in 5 experiments) and a fall in the PCO2 of the blood. There were no consistent changes in the pH and PCO2 of the blood accompanying vasodepressor responses. 4. The vasopressor responses could be obtained over periods of perfusion lasting 4 hr or longer. 5. It is suggested that changes in the composition of blood equilibrated in the isolated perfused lung cannot be predicted from in vitro dissociation curves. PMID:5652881

Daly, I. de Burgh; Michel, C. C.; Ramsay, D. J.; Waaler, B. A.

1968-01-01

128

Noisy Ventilation Improves Lung Function  

NASA Astrophysics Data System (ADS)

It has been shown that mechanical ventilation in the setting of acute lung injury may propagate additional injury within the lung and numerous studies have been carried out to determine the optimal method of minimizing ventilator induced lung injury while still maintaining life-sustaining gas exchange. We have found that noise added to tidal volume and frequency, called noisy ventilation, during mechanical ventilation improves both lung mechanics and oxygenation in a rodent model of acute lung injury. Additionally, the standard deviation of the noise appears to be directly related to the magnitude of improvements seen with this ventilation modality in a manner similar to stochastic resonance. Furthermore, healthy guinea pigs that underwent with noisy ventilation exhibited increased surfactant content and reduced plasma proteins than their conventionally ventilated counterparts within the alveolar space of the lung. This suggests that not only did noisy ventilation induce endogenous surfactant release, but also served to reduce ventilator induced lung injury in this animal model. In conclusion, noisy ventilation improves blood oxygenation during acute lung injury and also serves to enhance lung function and reduce ventilator induced lung injury in healthy lungs.

Suki, Béla; Arold, Stephen P.; Alencar, Adriano; Lutchen, Kenneth R.; Ingenito, Edward P.

2003-05-01

129

ASHRAE and residential ventilation  

SciTech Connect

In the last quarter of a century, the western world has become increasingly aware of environmental threats to health and safety. During this period, people psychologically retreated away from outdoors hazards such as pesticides, smog, lead, oil spills, and dioxin to the seeming security of their homes. However, the indoor environment may not be healthier than the outdoor environment, as has become more apparent over the past few years with issues such as mold, formaldehyde, and sick-building syndrome. While the built human environment has changed substantially over the past 10,000 years, human biology has not; poor indoor air quality creates health risks and can be uncomfortable. The human race has found, over time, that it is essential to manage the indoor environments of their homes. ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation was traditionally not a major concern because it was felt that, between operable windows and envelope leakage, people were getting enough outside air in their homes. In the quarter of a century since the first oil shock, houses have gotten much more energy efficient. At the same time, the kinds of materials and functions in houses changed in character in response to people's needs. People became more environmentally conscious and aware not only about the resources they were consuming but about the environment in which they lived. All of these factors contributed to an increasing level of public concern about residential indoor air quality and ventilation. Where once there was an easy feeling about the residential indoor environment, there is now a desire to define levels of acceptability and performance. Many institutions--both public and private--have interests in Indoor Air Quality (IAQ), but ASHRAE, as the professional society that has had ventilation as part of its mission for over 100 years, is the logical place to provide leadership. This leadership has been demonstrated most recently by the publication of the first nationally recognized standard on ventilation in homes, ASHRAE Standard 62.2-2003, which builds on work that has been part of ASHRAE for many years and will presumably continue. Homeowners and occupants, which includes virtually all of us, will benefit from the application of Standard 62.2 and use of the top ten list. This activity is exactly the kind of benefit to society that the founders of ASHRAE envisioned and is consistent with ASHRAE's mission and vision. ASHRAE members should be proud of their Society for taking leadership in residential ventilation.

Sherman, Max H.

2003-10-01

130

Regional lung perfusion estimated by electrical impedance tomography in a piglet model of lung collapse.  

PubMed

The assessment of the regional match between alveolar ventilation and perfusion in critically ill patients requires simultaneous measurements of both parameters. Ideally, assessment of lung perfusion should be performed in real-time with an imaging technology that provides, through fast acquisition of sequential images, information about the regional dynamics or regional kinetics of an appropriate tracer. We present a novel electrical impedance tomography (EIT)-based method that quantitatively estimates regional lung perfusion based on first-pass kinetics of a bolus of hypertonic saline contrast. Pulmonary blood flow was measured in six piglets during control and unilateral or bilateral lung collapse conditions. The first-pass kinetics method showed good agreement with the estimates obtained by single-photon-emission computerized tomography (SPECT). The mean difference (SPECT minus EIT) between fractional blood flow to lung areas suffering atelectasis was -0.6%, with a SD of 2.9%. This method outperformed the estimates of lung perfusion based on impedance pulsatility. In conclusion, we describe a novel method based on EIT for estimating regional lung perfusion at the bedside. In both healthy and injured lung conditions, the distribution of pulmonary blood flow as assessed by EIT agreed well with the one obtained by SPECT. The method proposed in this study has the potential to contribute to a better understanding of the behavior of regional perfusion under different lung and therapeutic conditions. PMID:21960654

Borges, João Batista; Suarez-Sipmann, Fernando; Bohm, Stephan H; Tusman, Gerardo; Melo, Alexandre; Maripuu, Enn; Sandström, Mattias; Park, Marcelo; Costa, Eduardo L V; Hedenstierna, Göran; Amato, Marcelo

2012-01-01

131

L. Slimani / Quantification of liver perfusion with PET 1 Quantification of liver perfusion with [15  

E-print Network

L. Slimani / Quantification of liver perfusion with PET 1 Quantification of liver perfusion. Running Title : Quantification of liver perfusion with PET Corresponding authors: Patricia Iozzo, MD, Ph of liver perfusion with PET 2 Abstract (204 words) Background/Aims: Hepatic perfusion plays an important

Paris-Sud XI, Université de

132

Insulated heat activated ventilator  

SciTech Connect

A building construction is described comprising a building structure and a ventilator, the ventilator including a stack defining a passage having an inlet and an outlet communicating with one another, a closure operative to normally seal the passage, insulating material supported by the closure and providing an air seal within the passage under normal conditions, and normally inoperative vent actuating means associated with the closure, the vent actuating means being operative in response to the presence of combustion products for disabling the closure, the closure and the insulating material being automatically released from the passage of the stack upon disablement of the closure whereby the combustion products are exhausted through the passage of the stack to atmosphere.

Kelly, T.L.

1993-05-25

133

Investigation on tunnel fire phenomenon under different emergency ventilation systems.  

E-print Network

???In this research study, the ventilating effect on tunnel fire development has been investigated under 4 ventilation mode throughout the tunnel: natural ventilation, fully-transverse ventilation,… (more)

Se, Mei King (???)

2009-01-01

134

Combating the Class Imbalance Problem in Small Sample Data Sets  

E-print Network

rigorously studied resampling methods, new algorithms, and feature selection methods, but no studies have been conducted to understand how well these methods combat the class imbalance problem. In particular, feature selection has been rarely studied outside...

Wasikowski, Michael

2009-07-07

135

Isolated perfused lung preparation for studying altered gaseous environments.  

PubMed Central

The isolated perfused lung (IPL) preparation is ideally suited to investigate lung dynamics and cellular function, and is easily adapted to investigating biochemical and physiological responses to environmental insults. The IPL offers several advantages which permit one to study endothelial/epithelial interactions that are often disrupted with other model systems (e.g., isolated cells, minces, slices, homogenates, etc.). The IPL developed in our laboratory was devised for the rat lung and allows four lungs to be perfused simultaneously in which control over ventilation, flow, pressure, pH, PO2 and PCO2 can be maintained. Isolated lungs perfused for 1 to 2 hr at a flow rate of 10 mL/min exhibit less that 2% weight gain, maintain normal ATP levels, and exhibit linear substrate uptake. Mechanisms leading to changes in vascular and airway resistance, lipid metabolism, vasoactive hormones, blood gases and changes in vascular permeability mediated by environmental insults can be quantified in the IPL preparation. PMID:6383801

Rhoades, R A

1984-01-01

136

Lightweight ventilated facade prototype: acoustic performance evaluation when the ventilation surface of  

E-print Network

Lightweight ventilated facade prototype: acoustic performance evaluation when the ventilation Conference 23-27 April 2012, Nantes, France 3801 #12;1. INTRODUCTION Lightweight ventilated facades cavity is almost totally open, fully ventilated and not very wide. Therefore, its contribution

Boyer, Edmond

137

Hamstrings strength imbalance in professional football (soccer) players in Australia.  

PubMed

The aim of this study was to describe the isokinetic thigh muscle strength profile of professional male football players in Australia. Concentric (60° and 240°/second) and eccentric (30° and 120°/second) hamstrings and quadriceps isokinetic strength was measured with a HUMAC NORM dynamometer. The primary variables were bilateral concentric and eccentric hamstring and quadriceps peak torque ratios, concentric hamstring-quadriceps peak torque ratios, and mixed ratios (eccentric hamstring 30°/second ÷ concentric quadriceps 240°/second). Hamstring strength imbalance was defined as deficits in any two of: bilateral concentric hamstring peak torque ratio < 0.86, bilateral eccentric hamstring peak torque ratio < 0.86, concentric hamstring-quadriceps ratio < 0.47, mixed ratio < 0.80. Fifty-five strength tests involving 42 players were conducted. Ten players (24%) were identified as having hamstring strength imbalance. Athletes with strength imbalance had significantly reduced concentric and eccentric bilateral hamstring peak torque ratios at all angular velocities tested; and reduced eccentric quadriceps peak torque (30°/second) in their stance leg, compared to those without strength imbalance. Approximately one in four players had preseason hamstring strength imbalance; and all strength deficits were observed in the stance leg. Concentric and eccentric hamstrings strength imbalance may impact in-season football performance, and could have implications for the future risk of injury. PMID:25426513

Ardern, Clare L; Pizzari, Tania; Wollin, Martin; Webster, Kate E

2014-11-25

138

Pretest Predictions for Ventilation Tests  

SciTech Connect

The objective of this calculation is to predict the temperatures of the ventilating air, waste package surface, concrete pipe walls, and insulation that will be developed during the ventilation tests involving various test conditions. The results will be used as input to the following three areas: (1) Decisions regarding testing set-up and performance. (2) Assessing how best to scale the test phenomena measured. (3) Validating numerical approach for modeling continuous ventilation. The scope of the calculation is to identify the physical mechanisms and parameters related to thermal response in the ventilation tests, and develop and describe numerical methods that can be used to calculate the effects of continuous ventilation. Sensitivity studies to assess the impact of variation of linear power densities (linear heat loads) and ventilation air flow rates are included. The calculation is limited to thermal effect only.

Y. Sun; H. Yang; H.N. Kalia

2007-01-17

139

Gastrointestinal perfusion in septic shock.  

PubMed

Septic shock is characterised by vasodilation, myocardial depression and impaired microcirculatory blood flow, resulting in redistribution of regional blood flow. Animal and human studies have shown that gastrointestinal mucosal blood flow is impaired in septic shock. This is consistent with abnormalities found in many other microcirculatory vascular beds. Gastrointestinal mucosal microcirculatory perfusion deficits have been associated with gut injury and a decrease in gut barrier function, possibly causing augmentation of systemic inflammation and distant organ dysfunction. A range of techniques have been developed and used to quantify these gastrointestinal perfusion abnormalities. The following techniques have been used to study gastrointestinal perfusion in humans: tonometry, laser Doppler flowmetry, reflectance spectrophotometry, near-infrared spectroscopy, orthogonal polarisation spectral imaging, indocyanine green clearance, hepatic vein catheterisation and measurements of plasma D-lactate. Although these methods share the ability to predict outcome in septic shock patients, it is important to emphasise that the measurement results are not interchangeable. Different techniques measure different elements of gastrointestinal perfusion. Gastric tonometry is currently the most widely used technique because of its non-invasiveness and ease of use. Despite all the recent advances, the usefulness of gastrointestinal perfusion parameters in clinical decision-making is still limited. Treatment strategies specifically aimed at improving gastrointestinal perfuision have failed to actually correct mucosal perfusion abnormalities and hence not shown to improve important clinical endpoints. Current and future treatment strategies for septic shock should be tested for their effects on gastrointestinal perfusion; to further clarify its exact role in patient management, and to prevent therapies detrimental to gastrointestinal perfusion being implemented. PMID:17933153

van Haren, F M P; Sleigh, J W; Pickkers, P; Van der Hoeven, J G

2007-10-01

140

MR Perfusion in the Lung  

Microsoft Academic Search

Pulmonary perfusion is the blood flow of an organ at the capillary level. It is closely related to the blood supply of the\\u000a lung and moreover to lung function. It is altered in various diseases of the lung such as pulmonary hypertension or cystic\\u000a fibrosis, etc. Therefore, perfusion is an important functional parameter in the diagnosis of pulmonary diseases and

Frank Risse

141

Laboratory Ventilation SafetyLaboratory Ventilation Safety J. Scott WardJ. Scott Ward  

E-print Network

Laboratory Ventilation SafetyLaboratory Ventilation Safety J. Scott WardJ. Scott Ward #12;In 1925. Labconco CorporationLabconco Corporation #12;Laboratory VentilationLaboratory Ventilation #12;Laboratory Ventilation ProductsLaboratory Ventilation Products #12;History of Fume HoodsHistory of Fume Hoods Thomas

Farritor, Shane

142

Ventilator management protocols in pediatrics.  

PubMed

Management of mechanical ventilation is a complex process with outcomes affected by multiple patient and caregiver variable. Well-constructed protocols represent the synthesis of best available evidence regarding ventilator management. In adults, protocols improve important outcomes such as duration of mechanical ventilation, length of stay, and complication rates; however, protocols are not uniformly successful. In pediatrics, the available evidence does not suggest that ventilator management protocols should be adopted routinely, which may be due to pediatric-specific attributes such as a generally shorter weaning duration. Evidence suggests support for protocols to carefully titrate sedation. In addition, daily assessment of SBTs improves patient outcomes and should be more uniformly adopted in pediatrics. Ventilator-related outcomes may be affected by other confounding factors such as nutrition and fluid balance. Specific subpopulations, such as children who have congenital heart disease, may present opportunities for focused use of ventilator management protocols. Protocolized ventilation has an important place in trials of new therapeutic strategies such as surfactant or proning. It is hoped that future research will further define the appropriate use of protocols in the general PICU population. Although specific protocols cannot be routinely recommended, a multidisciplinary team approach to synthesizing available literature and determining best practice is a useful model. This approach will foster "team ownership" of ventilator management by all involved, thus engendering the best possible outcomes for critically ill children who require mechanical ventilation. PMID:16952800

Graham, Alan S; Kirby, Aileen L

2006-09-01

143

Mild Endotoxemia during Mechanical Ventilation Produces Spatially Heterogeneous Pulmonary Neutrophilic Inflammation in Sheep  

PubMed Central

Background There is limited information on the regional inflammatory effects of mechanical ventilation and endotoxemia on the production of acute lung injury. Measurement of 18F-fluorodeoxyglucose (18F-FDG) uptake with Positron Emission Tomography allows for the regional, in vivo and non-invasive, assessment of neutrophilic inflammation. We tested whether mild endotoxemia combined with large tidal volume mechanical ventilation bounded by pressures within clinically acceptable limits could yield measurable and anatomically localized neutrophilic inflammation. Methods Sheep were mechanically ventilated with plateau pressures=30–32 cmH2O and positive end-expiratory pressure=0 for 2h. Six sheep received IV endotoxin (10 ng.kg?1.min?1) while 6 did not (controls), in sequentially performed studies. We imaged with Positron Emission Tomography the intrapulmonary kinetics of infused 13N-nitrogen and 18F-FDG to compute regional perfusion and 18F-FDG uptake. Transmission scans were used to assess aeration. Results Mean gas fraction and perfusion distribution were similar between groups. In contrast, a significant increase in 18F-FDG uptake was observed in all lung regions of the endotoxin group. In this group, 18F-FDG uptake in middle and dorsal regions was significantly larger than that in ventral regions. Multivariate analysis showed that 18F-FDG uptake was associated with regional aeration (p<0.01) and perfusion (p<0.01). Conclusions Mild short-term endotoxemia in the presence of heterogeneous lung aeration and mechanical ventilation with pressures within clinically acceptable limits produces marked spatially heterogeneous increases in pulmonary neutrophilic inflammation. The dependence of inflammation on aeration and perfusion suggests a multifactorial basis for that finding. 18F-FDG uptake may be a sensitive marker of pulmonary neutrophilic inflammation in the studied conditions. PMID:20179503

Costa, Eduardo L.V.; Musch, Guido; Winkler, Tilo; Schroeder, Tobias; Harris, R. Scott; Jones, Hazel A; Venegas, Jose G.; Vidal Melo, Marcos F.

2009-01-01

144

Perfusion effects and hydrodynamics.  

PubMed

Biological processes within living systems are significantly influenced by the motion of the liquids and gases to which those tissues are exposed. Accordingly, tissue engineers must not only understand hydrodynamic phenomena, but also appreciate the vital role of those phenomena in cellular and physiologic processes both in vitro and in vivo. In particular, understanding the fundamental principles of fluid flow underlying perfusion effects in the organ-level internal environment and their relation to the cellular microenvironment is essential to successfully mimicking tissue behavior. In this work, the major principles of hemodynamic flow and transport are summarized, to provide readers with a physical understanding of these important issues. In particular, since quantifying hemodynamic events through experiments can require expensive and invasive techniques, the benefits that can be derived from the use of computational fluid dynamics (CFD) packages and neural networking (NN) models are stressed. A capstone illustration based on analysis of the hemodynamics of aortic aneurysms is presented as a representative example of this approach, to stress the importance of tissue responses to flow-induced events. PMID:17195462

Peattie, Robert A; Fisher, Robert J

2007-01-01

145

CAD of myocardial perfusion  

NASA Astrophysics Data System (ADS)

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

Storm, Corstiaan J.; Slump, Cornelis H.

2007-03-01

146

46 CFR 116.610 - Ventilation ducts.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ventilation ducts. 116.610 Section 116.610 Shipping COAST GUARD, DEPARTMENT OF HOMELAND...PASSENGERS CONSTRUCTION AND ARRANGEMENT Ventilation § 116.610 Ventilation ducts. (a) For the...

2010-10-01

147

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Ventilation. 194.20-5 Section 194...or Storerooms § 194.20-5 Ventilation. (a) Chemical storerooms shall be equipped with a power ventilation system of exhaust type. The...

2012-10-01

148

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ventilation. 194.20-5 Section 194...or Storerooms § 194.20-5 Ventilation. (a) Chemical storerooms shall be equipped with a power ventilation system of exhaust type. The...

2010-10-01

149

24 CFR 3285.505 - Crawlspace ventilation.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Crawlspace ventilation. 3285.505 Section 3285.505...Features § 3285.505 Crawlspace ventilation. (a) A crawlspace with skirting must be provided with ventilation openings. The minimum net area...

2010-04-01

150

24 CFR 3285.505 - Crawlspace ventilation.  

...2014-04-01 false Crawlspace ventilation. 3285.505 Section 3285.505...Features § 3285.505 Crawlspace ventilation. (a) A crawlspace with skirting must be provided with ventilation openings. The minimum net area...

2014-04-01

151

24 CFR 3285.505 - Crawlspace ventilation.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Crawlspace ventilation. 3285.505 Section 3285.505...Features § 3285.505 Crawlspace ventilation. (a) A crawlspace with skirting must be provided with ventilation openings. The minimum net area...

2013-04-01

152

24 CFR 3285.505 - Crawlspace ventilation.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Crawlspace ventilation. 3285.505 Section 3285.505...Features § 3285.505 Crawlspace ventilation. (a) A crawlspace with skirting must be provided with ventilation openings. The minimum net area...

2012-04-01

153

24 CFR 3285.505 - Crawlspace ventilation.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Crawlspace ventilation. 3285.505 Section 3285.505...Features § 3285.505 Crawlspace ventilation. (a) A crawlspace with skirting must be provided with ventilation openings. The minimum net area...

2011-04-01

154

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ventilation. 194.20-5 Section 194...or Storerooms § 194.20-5 Ventilation. (a) Chemical storerooms shall be equipped with a power ventilation system of exhaust type. The...

2011-10-01

155

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ventilation. 194.20-5 Section 194...or Storerooms § 194.20-5 Ventilation. (a) Chemical storerooms shall be equipped with a power ventilation system of exhaust type. The...

2013-10-01

156

Laboratory and Industrial Ventilation  

NASA Technical Reports Server (NTRS)

This handbook supplements the Facilities Engineering Handbook (NHB 7320.1) and provides additional policies and criteria for uniform application to ventilation systems. It expands basic requirements, provides additional design and construction guidance, and places emphasis on those design considerations which will provide for greater effectiveness in the use of these systems. The provisions of this handbook are applicable to all NASA field installations and the Jet Propulsion Laboratory. Since supply of this handbook is limited, abstracts of the portion or portions applicable to a given requirement will be made for the individual specific needs encountered rather than supplying copies of the handbook as has been past practice.

1972-01-01

157

Hepatic Blood Perfusion Estimated by Dynamic Contrast-Enhanced Computed Tomography in Pigs Limitations of the Slope Method  

PubMed Central

Objective To determine whether dynamic contrast-enhanced computed tomography (DCE-CT) and the slope method can provide absolute measures of hepatic blood perfusion from hepatic artery (HA) and portal vein (PV) at experimentally varied blood flow rates. Materials and Methods Ten anesthetized 40-kg pigs underwent DCE-CT during periods of normocapnia (normal flow), hypocapnia (decreased flow), and hypercapnia (increased flow), which was induced by adjusting the ventilation. Reference blood flows in HA and PV were measured continuously by surgically-placed ultrasound transit-time flowmeters. For each capnic condition, the DCE-CT estimated absolute hepatic blood perfusion from HA and PV were calculated using the slope method and compared with flowmeter based absolute measurements of hepatic perfusions and relative errors were analyzed. Results The relative errors (mean±SEM) of the DCE-CT based perfusion estimates were ?21±23% for HA and 81±31% for PV (normocapnia), 9±23% for HA and 92±42% for PV (hypocapnia), and 64±28% for HA and ?2±20% for PV (hypercapnia). The mean relative errors for HA were not significantly different from zero during hypo- and normocapnia, and the DCE-CT slope method could detect relative changes in HA perfusion between scans. Infusion of contrast agent led to significantly increased hepatic blood perfusion, which biased the PV perfusion estimates. Conclusions Using the DCE-CT slope method, HA perfusion estimates were accurate at low and normal flow rates whereas PV perfusion estimates were inaccurate and imprecise. At high flow rate, both HA perfusion estimates were significantly biased. PMID:22836307

Winterdahl, Michael; Sørensen, Michael; Keiding, Susanne; Mortensen, Frank V.; Alstrup, Aage K. O.; Hansen, Søren B.; Munk, Ole L.

2012-01-01

158

Subsurface Ventilation System Description Document  

Microsoft Academic Search

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development

Eric Loros

2001-01-01

159

Transpired Air Collectors - Ventilation Preheating  

SciTech Connect

Many commercial and industrial buildings have high ventilation rates. Although all that fresh air is great for indoor air quality, heating it can be very expensive. This short (2-page) fact sheet describes a technology available to use solar energy to preheat ventilation air and dramatically reduce utility bills.

Christensen, C.

2006-06-22

160

Mechanical ventilation in abdominal surgery.  

PubMed

One of the key challenges in perioperative care is to reduce postoperative morbidity and mortality. Patients who develop postoperative morbidity but survive to leave hospital have often reduced functional independence and long-term survival. Mechanical ventilation provides a specific example that may help us to shift thinking from treatment to prevention of postoperative complications. Mechanical ventilation in patients undergoing surgery has long been considered only as a modality to ensure gas exchange while allowing maintenance of anesthesia with delivery of inhaled anesthetics. Evidence is accumulating, however, suggesting an association between intraoperative mechanical ventilation strategy and postoperative pulmonary function and clinical outcome in patients undergoing abdominal surgery. Non-protective ventilator settings, especially high tidal volume (VT) (>10-12mL/kg) and the use of very low level of positive end-expiratory pressure (PEEP) (PEEP<5cmH2O) or no PEEP, may cause alveolar overdistension and repetitive tidal recruitment leading to ventilator-associated lung injury in patients with healthy lungs. Stimulated by previous findings in patients with acute respiratory distress syndrome, the use of lower tidal volume ventilation is becoming increasingly more common in the operating room. However, lowering tidal volume, though important, is only part of the overall multifaceted approach of lung protective mechanical ventilation. In this review, we aimed at providing the most recent and relevant clinical evidence regarding the use of mechanical ventilation in patients undergoing abdominal surgery. PMID:25153670

Futier, E; Godet, T; Millot, A; Constantin, J-M; Jaber, S

2014-01-01

161

New Ventilated Isolation Cage  

PubMed Central

A multifunction lid has been developed for a commercially available transparent animal cage which permits feeding, watering, viewing, long-term holding, and local transport of laboratory rodents on experiment while isolating the surrounding environment. The cage is airtight except for its inlet and exhaust high-efficiency particulate air filters, and it is completely steam-sterilizable. Opening of the cage's feed and water ports causes an inrush of high velocity air which prevents back-migration of aerosols and permits feeding and watering while eliminating need for chemical vapor decontamination. Ventilation system design permits the holding in adjacent cages of animals infected with different organisms without danger of cross-contamination; leaves the animal room odor-free; reduces required bedding changes to twice a month or less, and provides investigators with capability to control precisely individual cage ventilation rates. Forty-eight cages can be conveniently placed on a standard NIH “shoebox” cage rack (60 inches wide × 28 inches deep × 74 inches high) fitted with a simple manifold exhaust system. The entire system is mobile, requiring only an electrical power outlet. Principal application of the caging system is in the area of preventing exposure of animal caretakers to pathogenic substances associated with the animal host, and in reducing handling of animals and their exposure to extraneous contamination. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 9 PMID:5659368

Cook, Reginald O.

1968-01-01

162

Tracheostomy in mechanical ventilation.  

PubMed

Airway access for mechanical ventilation (MV) can be provided either by orotracheal intubation (OTI) or tracheostomy tube. During episodes of acute respiratory failure, patients are commonly ventilated through an orotracheal tube that represents an easy and rapid initial placement of the airway device. OTI avoids acute surgical complications such as bleeding, nerve and posterior tracheal wall injury, and late complications such as wound infection and tracheal lumen stenosis that may emerge due to tracheostomy tube placement. Tracheostomy is often considered when MV is expected to be applied for prolonged periods or for the improvement of respiratory status, as this approach provides airway protection, facilitates access for secretion removal, improves patient comfort, and promotes progression of care in and outside the intensive care unit (ICU). The aim of this review is to assess the frequency and performance of different surgical or percutaneous dilational tracheostomy and timing and safety procedures associated with the use of fiberoptic bronchoscopy and ultrasounds. Moreover, we analyzed the performance based on National European surveys to assess the current tracheostomy practice in ICUs. PMID:25111644

Terragni, Pierpaolo; Faggiano, Chiara; Martin, Erica L; Ranieri, V Marco

2014-08-01

163

Potential Role of Lung Ventilation Scintigraphy in the Assessment of COPD  

PubMed Central

Objective: To highlight the importance of the lung ventilation scintigraphy (LVS) to study the regional distribution of lung ventilation and to describe most frequent abnormal patterns of lung ventilation distribution obtained by this technique in COPD and to compare the information obtained by LVS with the that obtained by traditional lung function tests. Material and methods: The research was done in 20 patients with previously diagnosed COPD who were treated in Intensive care unit of Clinic for pulmonary diseases and TB “Podhrastovi” Clinical Center, University of Sarajevo in exacerbation of COPD during first three months of 2014. Each patient was undergone to testing of pulmonary function by body plethysmography and ventilation/perfusion lung scintigraphy with radio pharmaceutics Technegas, 111 MBq Tc -99m-MAA. We compared the results obtained by these two methods. Results: All patients with COPD have a damaged lung function tests examined by body plethysmography implying airflow obstruction, but LVS indicates not only airflow obstruction and reduced ventilation, but also indicates the disorders in distribution in lung ventilation. Conclusion: LVS may add further information to the functional evaluation of COPD to that provided by traditional lung function tests and may contribute to characterizing the different phenotypes of COPD. PMID:25132709

Cukic, Vesna; Begic, Amela

2014-01-01

164

Kinetics of reversible-sequestration of leukocytes by the isolated perfused rat lung  

SciTech Connect

The kinetics and morphology of sequestration and margination of rat leukocytes were studied using an isolated perfused and ventilated rat lung preparation. Whole rat blood, bone marrow suspension, or leukocyte suspensions, were used to perfuse the isolated rat lung. The lung was also perfused with latex particle suspensions and the passage of particles through the lung capillaries was studied. When a leukocyte suspension was perfused through the lung in the single-pass mode, the rate of sequestration decreased as more cells were perfused. In contrast, latex particles of a size comparable to that of leukocytes were totally stopped by the lung. When the leukocyte suspension was recirculated through the lung, cells were rapidly removed from circulation until a steady state was reached, after which no net removal of cells by the lung occurred. These results indicate that leukocytes are reversibly sequestered from circulation. The sequestered cells marginated and attached to the luminal surface of the endothelium of post-capillary venules and veins. A mathematical model was developed based on the assumption that the attachment and detachment of leukocytes to blood vessel walls follows first-order kinetics. The model correctly predicts the following characteristics of the system: (a) the kinetics of the sequestration of leukocytes by the lung; (b) the existence of a steady state when a suspension of leukocytes is recirculated through the lung; and (c) the independence of the fraction of cells remaining in circulation from the starting concentration for all values of starting concentration. (ERB)

Goliaei, B.

1980-08-01

165

4D micro-CT-based perfusion imaging in small animals  

NASA Astrophysics Data System (ADS)

Quantitative in-vivo imaging of lung perfusion in rodents can provide critical information for preclinical studies. However, the combined challenges of high temporal and spatial resolution have made routine quantitative perfusion imaging difficult in rodents. We have recently developed a dual tube/detector micro-CT scanner that is well suited to capture first-pass kinetics of a bolus of contrast agent used to compute perfusion information. Our approach is based on the paradigm that the same time density curves can be reproduced in a number of consecutive, small (i.e. 50?L) injections of iodinated contrast agent at a series of different angles. This reproducibility is ensured by the high-level integration of the imaging components of our system, with a micro-injector, a mechanical ventilator, and monitoring applications. Sampling is controlled through a biological pulse sequence implemented in LabVIEW. Image reconstruction is based on a simultaneous algebraic reconstruction technique implemented on a GPU. The capabilities of 4D micro-CT imaging are demonstrated in studies on lung perfusion in rats. We report 4D micro-CT imaging in the rat lung with a heartbeat temporal resolution of 140 ms and reconstructed voxels of 88 ?m. The approach can be readily extended to a wide range of important preclinical models, such as tumor perfusion and angiogenesis, and renal function.

Badea, C. T.; Johnston, S. M.; Lin, M.; Hedlund, L. W.; Johnson, G. A.

2009-02-01

166

Catheter based magnetic resonance compatible perfusion probe  

E-print Network

Neurosurgeons are using a thermal based technique to quantify brain perfusion. The thermal diffusion probe (TDP) technology measures perfusion in a relatively small volume of brain tissue. The neurosurgeon chooses the ...

Toretta, Cara Lynne

2007-01-01

167

Cardiac gated ventilation  

NASA Astrophysics Data System (ADS)

There are several theoretic advantages to synchronizing positive pressure breaths with the cardiac cycle, including the potential for improving distribution of pulmonary and myocardial blood flow and enhancing cardiac output. We evaluated the effects of synchronizing respiration to the cardiac cycle using a programmable ventilator and electron beam CT (EBCT) scanning. The hearts of anesthetized dogs were imaged during cardiac gated respiration with a 50msec scan aperture. Multislice, short axis, dynamic image data sets spanning the apex to base of the left ventricle were evaluated to determine the volume of the left ventricular chamber at end-diastole and end-systole during apnea, systolic and diastolic cardiac gating. We observed an increase in cardiac output of up to 30% with inspiration gated to the systolic phase of the cardiac cycle in a nonfailing model of the heart.

Hanson, C. William, III; Hoffman, Eric A.

1995-05-01

168

Solar ventilation and tempering  

NASA Astrophysics Data System (ADS)

The paper presents basic information about solar panels, designed, realized and used for solar ventilation of rooms. Used method of numerical flow simulation gives good overview about warming and flowing of the air in several kinds of realized panels (window, facade, chimney). Yearlong measurements give a good base for calculations of economic return of invested capital. The operation of the system in transient period (spring, autumn) prolongs the period without classical heating of the room or building, in winter the classical heating is supported. In the summer period the system, furnished with chimney, can exhaust inner warm air together with necessary cooling of the system by gravity circulation, only. System needs not any invoiced energy source; it is supplied entirely by solar energy. Large building systems are supported by classical electric fan respectively.

Adámek, Karel; Pavlů, Miloš; Bandouch, Milan

2014-08-01

169

Cardiac gated ventilation  

SciTech Connect

There are several theoretic advantages to synchronizing positive pressure breaths with the cardiac cycle, including the potential for improving distribution of pulmonary and myocardial blood flow and enhancing cardiac output. The authors evaluated the effects of synchronizing respiration to the cardiac cycle using a programmable ventilator and electron beam CT (EBCT) scanning. The hearts of anesthetized dogs were imaged during cardiac gated respiration with a 50 msec scan aperture. Multi slice, short axis, dynamic image data sets spanning the apex to base of the left ventricle were evaluated to determine the volume of the left ventricular chamber at end-diastole and end-systole during apnea, systolic and diastolic cardiac gating. The authors observed an increase in cardiac output of up to 30% with inspiration gated to the systolic phase of the cardiac cycle in a non-failing model of the heart.

Hanson, C.W. III [Hospital of the Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. Anesthesia; Hoffman, E.A. [Univ. of Iowa College of Medicine, Iowa City, IA (United States). Div. of Physiologic Imaging

1995-12-31

170

Marked differences between prone and supine sheep in effect of PEEP on perfusion distribution in zone II lung.  

PubMed

The classic four-zone model of lung blood flow distribution has been questioned. We asked whether the effect of positive end-expiratory pressure (PEEP) is different between the prone and supine position for lung tissue in the same zonal condition. Anesthetized and mechanically ventilated prone (n = 6) and supine (n = 5) sheep were studied at 0, 10, and 20 cm H2O PEEP. Perfusion was measured with intravenous infusion of radiolabeled 15-microm microspheres. The right lung was dried at total lung capacity and diced into pieces (approximately 1.5 cm3), keeping track of the spatial location of each piece. Radioactivity per unit weight was determined and normalized to the mean value for each condition and animal. In the supine posture, perfusion to nondependent lung regions decreased with little relative perfusion in nondependent horizontal lung planes at 10 and 20 cm H2O PEEP. In the prone position, the effect of PEEP was markedly different with substantial perfusion remaining in nondependent lung regions and even increasing in these regions with 20 cm H2O PEEP. Vertical blood flow gradients in zone II lung were large in supine, but surprisingly absent in prone, animals. Isogravitational perfusion heterogeneity was smaller in prone than in supine animals at all PEEP levels. Redistribution of pulmonary perfusion by PEEP ventilation in supine was largely as predicted by the zonal model in marked contrast to the findings in prone. The differences between postures in blood flow distribution within zone II strongly indicate that factors in addition to pulmonary arterial, venous, and alveolar pressure play important roles in determining perfusion distribution in the in situ lung. We suggest that regional variation in lung volume through the effect on vascular resistance is one such factor and that chest wall conformation and thoracic contents determine regional lung volume. PMID:15774701

Walther, Sten M; Johansson, Mats J; Flatebø, Torun; Nicolaysen, Anne; Nicolaysen, Gunnar

2005-09-01

171

External negative pressure ventilation techniques.  

PubMed

External ventilation was introduced at the beginning of the century to treat acute and chronic respiratory failure. Long-term negative pressure ventilation (NPV) has proved useful in patients with respiratory failure, secondary to a restrictive impairment of neuromusculoskeletal origin. Although NPV may be successfully used in acute-on-chronic respiratory failure in patients with chronic airflow obstruction (CAO), its use in the long-term management of this type of patient seems much less promising. The various types of ventilators, iron lung, pneumo-wrap and cuirass are discussed. All these prostheses, except for the pneumo-wrap, are connected to a pump able to generate negative and positive pressure. NPV must be a controlled ventilation, because an effective trigger is not yet available. The most important feature of the ventilator must be the ability to vary the ventilatory pattern to adapt the machine drive to the patient drive. The goal of NPV is not only to normalize gas exchange, but also to restore an effective spontaneous ventilation. This kind of ventilation has no negative effects on haemodynamics, because it does not vary physiological gradients of transthoracic pressure. However, due to lack of coordination between the respirator and the pharyngeal muscles of the patient, obstructive apnoeas may occur during NPV in sleeping patients. PMID:7711706

Schiavina, M; Fabiani, A; Gunella, G

1994-12-01

172

Subsurface Ventilation System Description Document  

SciTech Connect

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

Eric Loros

2001-07-25

173

Performance of ventilators for noninvasive positive pressure ventilation in children  

E-print Network

in children with neuromuscular disease [2, 3], upper airway obstruction and sleep apnea [4], and lung diseases the preset and measured airway pressure and between the tidal volume measured by the ventilator

Boyer, Edmond

174

Ventilator-delivered mask ventilation compared with three standard methods of mask ventilation in a manikin model  

Microsoft Academic Search

BackgroundLittle is known regarding the variations in effective ventilation during bag and mask resuscitation with standard methods compared with that delivered by ventilator-delivered mask ventilation (VDMV).AimTo measure the variations in delivered airway pressure, tidal volume (TV), minute ventilation (MV) and inspiratory time during a 3-min period of mask ventilation comparing VDMV with three commonly used hand-delivered methods of bag and

M. B. Tracy; J. Klimek; H. Coughtrey; V. Shingde; G. Ponnampalam; M. Hinder; R. Maheshwari; S. K. Tracy

2011-01-01

175

Ventilation Based on ASHRAE 62.2  

E-print Network

Indoor Ventilation Based on ASHRAE 62.2 Arnold Schwarzenegger Governor California Energy Commission Ventilation (ASHRAE 62.2) Minimum Best Practices Guide - Exhaust-Only Ventilation Introduction: The California/ASHRAE Standard 62.2-2007, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings (ASHRAE

176

Laboratory Ventilation Management Ralph Stuart, CHO  

E-print Network

Laboratory Ventilation Management Program Ralph Stuart, CHO Ellen Sweet, Laboratory Ventilation Specialist Cornell Department of Environmental Health and Safety 3/29/2013 #12;Laboratory Ventilation.1.2 Design and Construction Standards 10 7.1.3 Carbon Dioxide Ventilation Effectiveness Protocol 10 7.2 Job

Pawlowski, Wojtek

177

Preoperational test, vent building ventilation system  

SciTech Connect

Preoperational Test Procedure for Vent Building Ventilation System, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The Vent Building ventilation system provides ventilation, heating, cooling, and zone confinement control for the W-030 Project Vent Building. The tests verify correct System operation and correct indications displayed by the central Monitor and Control system.

Clifton, F.T., Westinghouse Hanford

1996-08-20

178

14 CFR 23.831 - Ventilation.  

...2014-01-01 2014-01-01 false Ventilation. 23.831 Section 23.831 Aeronautics...Cargo Accommodations § 23.831 Ventilation. (a) Each passenger and crew...adversely affect the ventilating air, the ventilation system must provide reasonable...

2014-01-01

179

14 CFR 23.831 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Ventilation. 23.831 Section 23.831 Aeronautics...Cargo Accommodations § 23.831 Ventilation. (a) Each passenger and crew...adversely affect the ventilating air, the ventilation system must provide reasonable...

2013-01-01

180

Preoperational test report, vent building ventilation system  

SciTech Connect

This represents a preoperational test report for Vent Building Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides Heating, Ventilation, and Air Conditioning (HVAC) for the W-030 Ventilation Building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-11-04

181

6. VIEW LOOKING SOUTHEAST AT VENTILATION EQUIPMENT IN SOUTH VENTILATION ...  

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

6. VIEW LOOKING SOUTHEAST AT VENTILATION EQUIPMENT IN SOUTH VENTILATION HOUSE. THIS AIR CONDITIONING SYSTEM WAS INSTALLED BY PARKS-CRAMER COMPANY OF FITCHBURG, MASSACHUSETTS WHEN THE MILL WAS CONSTRUCTED IN 1923-24. ONE AIR WASHER AND FAN ROOM EXTERIOR IS VISIBLE ON THE RIGHT. THE DUCTS FROM BOTH FAN ROOMS (CURVED METAL STRUCTURES AT CENTER AND LEFT OF PHOTO) ARE CONNECTED TO A COMMON AIR SHAFT. - Stark Mill, 117 Corinth Road, Hogansville, Troup County, GA

182

Reproducibility of regional lung ventilation distribution determined by electrical impedance tomography during mechanical ventilation  

Microsoft Academic Search

Electrical impedance tomography (EIT) has the potential to become a new tool for bedside monitoring of regional lung ventilation. The aim of our study was to assess the reproducibility of regional lung ventilation distribution determined by EIT during mechanical ventilation under identical ventilator settings. The experiments were performed on 10 anaesthetized supine pigs ventilated in a volume-controlled mode. EIT measurements

I Frerichs; G Schmitz; S Pulletz; G Zick; J Scholz; N Weiler

2007-01-01

183

Statistical inference of allelic imbalance from transcriptome data.  

PubMed

Next-generation sequencing and the availability of high-density genotyping arrays have facilitated an analysis of somatic and meiotic mutations at unprecedented level, but drawing sensible conclusions about the functional relevance of the detected variants still remains a formidable challenge. In this context, the study of allelic imbalance in intermediate RNA phenotypes may prove a useful means to elucidate the likely effects of DNA variants of unknown significance. We developed a statistical framework for the assessment of allelic imbalance in next-generation transcriptome sequencing (RNA-seq) data that requires neither an expression reference nor the underlying nuclear genotype(s), and that allows for allele miscalls. Using extensive simulation as well as publicly available whole-transcriptome data from European-descent individuals in HapMap, we explored the power of our approach in terms of both genotype inference and allelic imbalance assessment under a wide range of practically relevant scenarios. In so doing, we verified a superior performance of our methodology, particularly at low sequencing coverage, compared to the more simplistic approach of completely ignoring allele miscalls. Because the proposed framework can be used to assess somatic mutations and allelic imbalance in one and the same set of RNA-seq data, it will be particularly useful for the analysis of somatic genetic variation in cancer studies. PMID:21120951

Nothnagel, Michael; Wolf, Andreas; Herrmann, Alexander; Szafranski, Karol; Vater, Inga; Brosch, Mario; Huse, Klaus; Siebert, Reiner; Platzer, Matthias; Hampe, Jochen; Krawczak, Michael

2011-01-01

184

Reflex sympathetic imbalanceResponse to epidural blockade  

Microsoft Academic Search

Eleven patients (two male, nine female) were treated with epidural sympathetic blockade for reflex sympa thetic imbalance, an incomplete manifestation of reflex sympathetic dystrophy. Each had developed severe pain, sensitivity, and disability disproportionate to as sociated trauma. One patient injured an ankle, and the remaining 10 patients one or both knees (12 knees). Seven patients had undergone previous surgery. All

Amy L. Ladd; Kenneth E. DeHaven; Jaimala Thanik; Richard B. Patt; Michael Feuerstein

1989-01-01

185

Equivalence in Ventilation and Indoor Air Quality  

SciTech Connect

We ventilate buildings to provide acceptable indoor air quality (IAQ). Ventilation standards (such as American Society of Heating, Refrigerating, and Air-Conditioning Enginners [ASHRAE] Standard 62) specify minimum ventilation rates without taking into account the impact of those rates on IAQ. Innovative ventilation management is often a desirable element of reducing energy consumption or improving IAQ or comfort. Variable ventilation is one innovative strategy. To use variable ventilation in a way that meets standards, it is necessary to have a method for determining equivalence in terms of either ventilation or indoor air quality. This study develops methods to calculate either equivalent ventilation or equivalent IAQ. We demonstrate that equivalent ventilation can be used as the basis for dynamic ventilation control, reducing peak load and infiltration of outdoor contaminants. We also show that equivalent IAQ could allow some contaminants to exceed current standards if other contaminants are more stringently controlled.

Sherman, Max; Walker, Iain; Logue, Jennifer

2011-08-01

186

Myocardial perfusion scintigraphy: the evidence  

Microsoft Academic Search

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the

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

2004-01-01

187

Perfusion decellularization of whole organs.  

PubMed

The native extracellular matrix (ECM) outlines the architecture of organs and tissues. It provides a unique niche of composition and form, which serves as a foundational scaffold that supports organ-specific cell types and enables normal organ function. Here we describe a standard process for pressure-controlled perfusion decellularization of whole organs for generating acellular 3D scaffolds with preserved ECM protein content, architecture and perfusable vascular conduits. By applying antegrade perfusion of detergents and subsequent washes to arterial vasculature at low physiological pressures, successful decellularization of complex organs (i.e., hearts, lungs and kidneys) can be performed. By using appropriate modifications, pressure-controlled perfusion decellularization can be achieved in small-animal experimental models (rat organs, 4-5 d) and scaled to clinically relevant models (porcine and human organs, 12-14 d). Combining the unique structural and biochemical properties of native acellular scaffolds with subsequent recellularization techniques offers a novel platform for organ engineering and regeneration, for experimentation ex vivo and potential clinical application in vivo. PMID:24874812

Guyette, Jacques P; Gilpin, Sarah E; Charest, Jonathan M; Tapias, Luis F; Ren, Xi; Ott, Harald C

2014-01-01

188

Literature Review of Displacement Ventilation  

E-print Network

Performance Evaluation and Design Guidelines for Displacement Ventilation” by Chen and Clicksman (2003), were used to begin the literature search. Their references include papers, articles, and web sites presenting major contributions to the understanding...

Cho, S.; Im, P.; Haberl, J. S.

189

Transtracheal ventilation in oral surgery.  

PubMed Central

The use of transtracheal ventilation as a routine method of ventilation during anaesthesia for 60 patients with gross pathology requiring oral surgery is reported. Theoretical hazards of the technique and protection of the airway are discussed. There were no serious complications in this series. The technique is recommended as a simple and safe alternative to blind nasal intubation. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:6614769

Layman, P. R.

1983-01-01

190

Ventilation Model and Analysis Report  

SciTech Connect

This model and analysis report develops, validates, and implements a conceptual model for heat transfer in and around a ventilated emplacement drift. This conceptual model includes thermal radiation between the waste package and the drift wall, convection from the waste package and drift wall surfaces into the flowing air, and conduction in the surrounding host rock. These heat transfer processes are coupled and vary both temporally and spatially, so numerical and analytical methods are used to implement the mathematical equations which describe the conceptual model. These numerical and analytical methods predict the transient response of the system, at the drift scale, in terms of spatially varying temperatures and ventilation efficiencies. The ventilation efficiency describes the effectiveness of the ventilation process in removing radionuclide decay heat from the drift environment. An alternative conceptual model is also developed which evaluates the influence of water and water vapor mass transport on the ventilation efficiency. These effects are described using analytical methods which bound the contribution of latent heat to the system, quantify the effects of varying degrees of host rock saturation (and hence host rock thermal conductivity) on the ventilation efficiency, and evaluate the effects of vapor and enhanced vapor diffusion on the host rock thermal conductivity.

V. Chipman

2003-07-18

191

21 CFR 868.5905 - Noncontinuous ventilator (IPPB).  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Noncontinuous ventilator (IPPB). 868.5905 Section 868...Devices § 868.5905 Noncontinuous ventilator (IPPB). (a) Identification. A noncontinuous ventilator (intermittent positive...

2011-04-01

192

21 CFR 868.5905 - Noncontinuous ventilator (IPPB).  

...2014-04-01 false Noncontinuous ventilator (IPPB). 868.5905 Section 868...Devices § 868.5905 Noncontinuous ventilator (IPPB). (a) Identification. A noncontinuous ventilator (intermittent positive...

2014-04-01

193

Advanced Controls and Sustainable Systems for Residential Ventilation  

E-print Network

1 Advanced Controls and Sustainable Systems for Residential Ventilation William J.N. Turner & Iain..................................................................................................................... 8 Residential Ventilation Standards..........................................................................................9 Passive and Hybrid Ventilation

194

21 CFR 868.5905 - Noncontinuous ventilator (IPPB).  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Noncontinuous ventilator (IPPB). 868.5905 Section 868...Devices § 868.5905 Noncontinuous ventilator (IPPB). (a) Identification. A noncontinuous ventilator (intermittent positive...

2010-04-01

195

21 CFR 868.5905 - Noncontinuous ventilator (IPPB).  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Noncontinuous ventilator (IPPB). 868.5905 Section 868...Devices § 868.5905 Noncontinuous ventilator (IPPB). (a) Identification. A noncontinuous ventilator (intermittent positive...

2012-04-01

196

21 CFR 868.5905 - Noncontinuous ventilator (IPPB).  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Noncontinuous ventilator (IPPB). 868.5905 Section 868...Devices § 868.5905 Noncontinuous ventilator (IPPB). (a) Identification. A noncontinuous ventilator (intermittent positive...

2013-04-01

197

Comparison of the efficacy of University of Wisconsin solution and Newcastle organ perfusion fluid in the preservation of livers for transplantation.  

PubMed

University of Wisconsin solution (UW) is now used widely for the preservation of livers for transplantation. However, the use of commercial solutions has added considerably to the cost. We were able to produce a local version of organ perfusion fluid (NOPF) incorporating all the constituents of UW except for the hydroxyethyl starch and adenosine. We compared graft outcome using NOPF with imported grafts perfused with commercial UW solution. The two recipient groups (15 patients each) were similar with respect to age and sex distribution, urgency of transplantation, regraft status and patient and graft survival. Postoperative duration of ventilation, dialysis requirements, peak bilirubin, peak ALT and lowest unsupported prothrombin time were also similar in both groups. In conclusion, local perfusion fluids based on UW can be produced without detriment to graft outcome with considerable financial savings. At our institution, this represents a reduction of 33% in the cost of perfusion fluids. PMID:9665022

Krishnan, H; Hannon, M F; Bawa, S M; Talbot, D; Mirza, D; Manas, D; Thick, M

1998-01-01

198

Early Fault Feature Extraction of Rotor Imbalance and Self-Healing Monitoring  

Microsoft Academic Search

Based on the analysis of rotor imbalance mechanism, the presumption of extracting early fault features of rotor imbalance through the utilization of wavelet packet noise elimination and feature zoom as well as conducting self healing monitoring over the rotor imbalance through the utilization of electromagnetic induction principle is proposed. In addition, simulation experiment is applied to prove the feasibility of

Wang Zhongsheng; Wang Xiang; Luo Baopeng

2009-01-01

199

Right axillary and femoral artery perfusion with mild hypothermia for aortic arch replacement  

PubMed Central

Objectives Aortic arch replacement is associated with increased mortality and morbidity especially in acute type-A aortic dissection. Although hypothermic circulatory arrest with selective antegrade cerebral perfusion has been widely used because of its excellent cerebral protection, its optimal perfusion characteristics are unknown. The present study investigates clinical results obtained after perfusion method modification and temperature management during cardiopulmonary bypass (CPB). Methods Between July 2010 and August 2012, 16 consecutive adult patients (mean age 50.0 yr?±?14.1 yr, range 25 yr to 73 yr, 12 males, 4 females) who presented with acute Stanford type-A aortic dissection underwent aortic arch replacement (total arch, n?=?11; hemiarch, n?=?5) under mild hypothermia (31.1°C?±?1.5°C) with right axillary and femoral artery perfusion. Results The mean CPB time was 201 min?±?53 min, and the mean myocardial ischemic time was 140 min?±?42 min. The mean selective cerebral perfusion time was 80 min?±?16 min, and the mean lower-body circulatory arrest time was 20 min?±?13 min. No patient death occurred within 30 post-operative days. The following details were observed: new post-operative permanent neurologic deficit in 1 patient (6.3%), temporary neurologic deficit in 2 patients (12.5%), acute renal dysfunction (creatinine level?>?230 umol/L) in 3 patients (18.8%) and mechanical ventilation?>?72 h in 5 patients (31.2%). Conclusions Aortic arch replacement for acute type-A aortic dissection under mild hypothermia with right axillary and femoral artery perfusion could be safely performed in the patient cohort. PMID:24885031

2014-01-01

200

Vorticity imbalance and stability in relation to convection  

NASA Technical Reports Server (NTRS)

A complete synoptic-scale vorticity budget was related to convection storm development in the eastern two-thirds of the United States. The 3-h sounding interval permitted a study of time changes of the vorticity budget in areas of convective storms. Results of analyses revealed significant changes in values of terms in the vorticity equation at different stages of squall line development. Average budgets for all areas of convection indicate systematic imbalance in the terms in the vorticity equation. This imbalance resulted primarily from sub-grid scale processes. Potential instability in the lower troposphere was analyzed in relation to the development of convective activity. Instability was related to areas of convection; however, instability alone was inadequate for forecast purposes. Combinations of stability and terms in the vorticity equation in the form of indices succeeded in depicting areas of convection better than any one item separately.

Read, W. L.; Scoggins, J. R.

1977-01-01

201

Vasomotor tone does not affect perfusion heterogeneity and gas exchange in normal primate lungs during normoxia  

NASA Technical Reports Server (NTRS)

To determine whether vasoregulation is an important cause of pulmonary perfusion heterogeneity, we measured regional blood flow and gas exchange before and after giving prostacyclin (PGI(2)) to baboons. Four animals were anesthetized with ketamine and mechanically ventilated. Fluorescent microspheres were used to mark regional perfusion before and after PGI(2) infusion. The lungs were subsequently excised, dried inflated, and diced into approximately 2-cm(3) pieces (n = 1,208-1,629 per animal) with the spatial coordinates recorded for each piece. Blood flow to each piece was determined for each condition from the fluorescent signals. Blood flow heterogeneity did not change with PGI(2) infusion. Two other measures of spatial blood flow distribution, the fractal dimension and the spatial correlation, did not change with PGI(2) infusion. Alveolar-arterial O(2) differences did not change with PGI(2) infusion. We conclude that, in normal primate lungs during normoxia, vasomotor tone is not a significant cause of perfusion heterogeneity. Despite the heterogeneous distribution of blood flow, active regulation of regional perfusion is not required for efficient gas exchange.

Glenny, R. W.; Robertson, H. T.; Hlastala, M. P.

2000-01-01

202

Patterns of pulmonary perfusion scans in normal subjects. IV. The prevalence of abnormal scans in smokers 30 to 49 years of age  

SciTech Connect

The usefulness of ventilation-perfusion scans in the diagnosis of pulmonary embolism is limited by the wide range of pulmonary diseases that are associated with abnormal scans, and by the largely undetermined prevalence of abnormal scans in persons without cardiopulmonary disease. In prior studies, we found perfusion defects to be rarely present in young persons and in older nonsmokers. To determine if normal older smokers have a higher prevalence of abnormal ventilation and perfusion scans, we performed six-view /sup 99m/Tc perfusion (Q) scans and /sup 133/Xe ventilation (V) scans in 40 subjects 30 to 49 yr of age who had no known cardiopulmonary disease. Each subject had undergone a history, physical examination, electrocardiogram, spirometry, and posteroanterior chest roentgenogram prior to scanning. All V and Q scans were interpreted blindly and independently by two experienced readers. No subject demonstrated a lobar or segmental defect on two views. One subject had a matched subsegmental defect, and one subject had delayed washout from a subsegmental area of the right upper lobe during V scanning, with a normal Q scan. We conclude that abnormal V and Q scans are uncommon among normal smokers 30 to 49 yr of age.

Fedullo, P.F.; Kapitan, K.S.; Brewer, N.S.; Ashburn, W.L.; Hartman, M.T.; Moser, K.M.

1989-05-01

203

Intestinal perfusion monitoring using photoplethysmography  

PubMed Central

Abstract. In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed. PMID:23942635

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

2013-01-01

204

Intestinal perfusion monitoring using photoplethysmography.  

PubMed

In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed. PMID:23942635

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

2013-08-01

205

Residential ventilation standards scoping study  

SciTech Connect

The goals of this scoping study are to identify research needed to develop improved ventilation standards for California's Title 24 Building Energy Efficiency Standards. The 2008 Title 24 Standards are the primary target for the outcome of this research, but this scoping study is not limited to that timeframe. We prepared this scoping study to provide the California Energy Commission with broad and flexible options for developing a research plan to advance the standards. This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the ventilation needs of California residences, determining the bases for setting residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and corresponding levels of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

McKone, Thomas E.; Sherman, Max H.

2003-10-01

206

Money and age in schools: Bullying and power imbalances.  

PubMed

School bullying continues to be a serious problem around the world. Thus, it seems crucial to clearly identify the risk factors associated with being a victim or a bully. The current study focused in particular on the role that age and socio-economic differences between classmates could play on bullying. Logistic and multilevel analyses were conducted using data from 53,316 5th and 9th grade students from a representative sample of public and private Colombian schools. Higher age and better family socio-economic conditions than classmates were risk factors associated with being a bully, while younger age and poorer socio-economic conditions than classmates were associated with being a victim of bullying. Coming from authoritarian families or violent neighborhoods, and supporting beliefs legitimizing aggression, were also associated with bullying and victimization. Empathy was negatively associated with being a bully, and in some cases positively associated with being a victim. The results highlight the need to take into account possible sources of power imbalances, such as age and socio-economic differences among classmates, when seeking to prevent bullying. In particular, interventions focused on peer group dynamics might contribute to avoid power imbalances or to prevent power imbalances from becoming power abuse. Aggr. Behav. 9999:XX-XX, 2014. © 2014 Wiley Periodicals, Inc. PMID:25219327

Chaux, Enrique; Castellanos, Melisa

2014-09-12

207

Drillstring component mass imbalance: A major source of downhole vibrations  

SciTech Connect

A study consisting of surface and downhole field experiments, theoretical analysis, and numerical modeling has shown that mass imbalance of drillstring components is a major source of downhole lateral vibrations. Factors that contribute to imbalance include bore misalignment, initial curvature, and gradual wear during service. Field experiments were conducted on the surface to quantify drillstring component mass imbalance for modeling purposes. Tests focused on drill collars. Lateral displacements of collars were measured while each was rotated in the derrick, and results were interpreted with simple models. All collars were unbalanced to some extent. A similar procedure can be used in the field to identify nearly balanced collars for use near the bit. Field experiments conducted downhole used a bull nose in place of a bit to evaluate drillstring vibrations without the bit as a source. A pendulum assembly with stabilizers 65 and 95 ft from the bull nose was used. Simultaneous surface and downhole measurements of accelerations were made. Lateral shocks caused by collar/wellbore collisions were measured at various locations in the drillstring at rotary speeds that caused the collars to whirl. Acceleration magnitudes were heavily influenced by local formation strength. Backward whirl of the drillstring was observed while rotating both on and off bottom. It was identified through downhole measurements, and was associated with sudden, dramatic increases in surface torque.

Dykstra, M.W.; Chen, D.C.K.; Warren, T.M.; Azar, J.J. [Univ. of Tulsa, OK (United States)

1996-12-01

208

Survey of the Visual Exploration and Analysis of Perfusion Data  

Microsoft Academic Search

Dynamic contrast-enhanced image data (perfusion data) are used to characterize regional tissue perfusion. Perfusion data consist of a sequence of images, acquired after a contrast agent bolus is applied. Perfusion data are used for diagnostic purposes in oncology, ischemic stroke assessment or myocardial ischemia. The diagnostic evaluation of perfusion data is challenging, since the data is complex and exhibits various

Bernhard Preim; Steffen Oeltze; Matej Mlejnek; Eduard Gröller; Anja Hennemuth; Sarah Behrens

2009-01-01

209

ICA-based compensation for IQ imbalance in OFDM optical fiber communication  

NASA Astrophysics Data System (ADS)

A method based on the independent component analysis (ICA) is proposed to compensate the in-phase and quadrature-phase the (IQ) imbalance in orthogonal frequency division multiplexing (OFDM) optical fiber communication systems. The mathematical model of IQ imbalance system has been analyzed. Then, ICA algorithm is applied in the system to combat the mirror interference introduced by IQ imbalance. This algorithm can realize the joint compensation of both transmitter and receiver IQ imbalance with the optical channel that contains noise, attenuation and chromatic dispersion. The simulation shows that the performance degradation caused by IQ imbalance can be compensated by ICA algorithm effectively.

Jiang, Shan; Hu, Guijun; Li, Zhaoxi; Mu, Liping; Zhang, Jingdong

2014-01-01

210

REVIEW Open Access Ventilator-induced lung injury: historical  

E-print Network

REVIEW Open Access Ventilator-induced lung injury: historical perspectives and clinical Mechanical ventilation can produce lung physiological and morphological alterations termed ventilator to mechanically ventilated patients, and thus of the stress applied to their lungs, unambiguously contributed

Paris-Sud XI, Université de

211

30 CFR 57.8532 - Opening and closing ventilation doors.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Opening and closing ventilation doors. 57.8532 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8532 Opening and closing ventilation doors. When ventilation...

2012-07-01

212

30 CFR 57.8532 - Opening and closing ventilation doors.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Opening and closing ventilation doors. 57.8532 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8532 Opening and closing ventilation doors. When ventilation...

2011-07-01

213

30 CFR 57.8532 - Opening and closing ventilation doors.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Opening and closing ventilation doors. 57.8532 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8532 Opening and closing ventilation doors. When ventilation...

2013-07-01

214

30 CFR 57.8532 - Opening and closing ventilation doors.  

...2014-07-01 false Opening and closing ventilation doors. 57.8532 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8532 Opening and closing ventilation doors. When ventilation...

2014-07-01

215

30 CFR 57.8532 - Opening and closing ventilation doors.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Opening and closing ventilation doors. 57.8532 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8532 Opening and closing ventilation doors. When ventilation...

2010-07-01

216

33 CFR 183.620 - Natural ventilation system.  

...2014-07-01 false Natural ventilation system. 183.620 Section 183.620 Navigation...Ventilation § 183.620 Natural ventilation system...the atmosphere, a natural ventilation system...paragraph (c) of this section; (3)...

2014-07-01

217

33 CFR 183.620 - Natural ventilation system.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Natural ventilation system. 183.620 Section 183.620 Navigation...Ventilation § 183.620 Natural ventilation system...the atmosphere, a natural ventilation system...paragraph (c) of this section; (3)...

2013-07-01

218

33 CFR 183.620 - Natural ventilation system.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Natural ventilation system. 183.620 Section 183.620 Navigation...Ventilation § 183.620 Natural ventilation system...the atmosphere, a natural ventilation system...paragraph (c) of this section; (3)...

2012-07-01

219

33 CFR 183.620 - Natural ventilation system.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Natural ventilation system. 183.620 Section 183.620 Navigation...Ventilation § 183.620 Natural ventilation system...the atmosphere, a natural ventilation system...paragraph (c) of this section; (3)...

2011-07-01

220

Human versus Computer Controlled Selection of Ventilator Settings: An Evaluation of Adaptive Support Ventilation and Mid-Frequency Ventilation  

PubMed Central

Background. There are modes of mechanical ventilation that can select ventilator settings with computer controlled algorithms (targeting schemes). Two examples are adaptive support ventilation (ASV) and mid-frequency ventilation (MFV). We studied how different clinician-chosen ventilator settings are from these computer algorithms under different scenarios. Methods. A survey of critical care clinicians provided reference ventilator settings for a 70?kg paralyzed patient in five clinical/physiological scenarios. The survey-derived values for minute ventilation and minute alveolar ventilation were used as goals for ASV and MFV, respectively. A lung simulator programmed with each scenario's respiratory system characteristics was ventilated using the clinician, ASV, and MFV settings. Results. Tidal volumes ranged from 6.1 to 8.3?mL/kg for the clinician, 6.7 to 11.9?mL/kg for ASV, and 3.5 to 9.9?mL/kg for MFV. Inspiratory pressures were lower for ASV and MFV. Clinician-selected tidal volumes were similar to the ASV settings for all scenarios except for asthma, in which the tidal volumes were larger for ASV and MFV. MFV delivered the same alveolar minute ventilation with higher end expiratory and lower end inspiratory volumes. Conclusions. There are differences and similarities among initial ventilator settings selected by humans and computers for various clinical scenarios. The ventilation outcomes are the result of the lung physiological characteristics and their interaction with the targeting scheme. PMID:23119152

Mireles-Cabodevila, Eduardo; Diaz-Guzman, Enrique; Arroliga, Alejandro C.; Chatburn, Robert L.

2012-01-01

221

14 CFR 252.9 - Ventilation systems.  

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever the ventilation system is not fully functioning. Fully...

2011-01-01

222

14 CFR 252.9 - Ventilation systems.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.9 Ventilation systems. Air carriers shall prohibit smoking whenever the ventilation system is not fully functioning. Fully...

2010-01-01

223

JAMA Patient Page: Ventilator-Associated Pneumonia  

MedlinePLUS

... of the American Medical Association JAMA PATIENT PAGE Ventilator-Associated Pneumonia V entilator-associated pneumonia , defined as ... and life-threatening infection. Because individuals who contract ventilator-associated pneumonia are already critically ill (requiring mechanical ...

224

14 CFR 121.219 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...and Space 3 2011-01-01 2011-01-01 false Ventilation. 121.219 Section 121.219 Aeronautics and Space...OPERATIONS Special Airworthiness Requirements § 121.219 Ventilation. Each passenger or crew compartment must be suitably...

2011-01-01

225

14 CFR 125.117 - Ventilation.  

...and Space 3 2014-01-01 2014-01-01 false Ventilation. 125.117 Section 125.117 Aeronautics and Space...AIRCRAFT Special Airworthiness Requirements § 125.117 Ventilation. Each passenger or crew compartment must be suitably...

2014-01-01

226

14 CFR 125.117 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...and Space 3 2012-01-01 2012-01-01 false Ventilation. 125.117 Section 125.117 Aeronautics and Space...AIRCRAFT Special Airworthiness Requirements § 125.117 Ventilation. Each passenger or crew compartment must be suitably...

2012-01-01

227

14 CFR 121.219 - Ventilation.  

...and Space 3 2014-01-01 2014-01-01 false Ventilation. 121.219 Section 121.219 Aeronautics and Space...OPERATIONS Special Airworthiness Requirements § 121.219 Ventilation. Each passenger or crew compartment must be suitably...

2014-01-01

228

14 CFR 29.831 - Ventilation.  

...and Space 1 2014-01-01 2014-01-01 false Ventilation. 29.831 Section 29.831 Aeronautics and Space...Construction Personnel and Cargo Accommodations § 29.831 Ventilation. (a) Each passenger and crew compartment must...

2014-01-01

229

14 CFR 121.219 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...and Space 3 2012-01-01 2012-01-01 false Ventilation. 121.219 Section 121.219 Aeronautics and Space...OPERATIONS Special Airworthiness Requirements § 121.219 Ventilation. Each passenger or crew compartment must be suitably...

2012-01-01

230

46 CFR 194.10-25 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...MATERIALS Magazines § 194.10-25 Ventilation. (a) Integral magazines. (1) All integral magazines shall be provided with natural or mechanical ventilation. Design calculations shall be submitted demonstrating that the system...

2010-10-01

231

Ventilator-Associated Pneumonia: A Review  

Microsoft Academic Search

Ventilator-associated pneumonia is the most frequent intensive care unit (ICU)-related infection in patients requiring mechanical ventilation. In contrast to other ICU-related infections, which have a low mortality rate, the mortality rate for ventilator-associated pneumonia ranges from 20% to 50%. These clinically significant infections prolong duration of mechanical ventilation and ICU length of stay, underscoring the financial burden these infections impose

Kimberly A. Davis

2006-01-01

232

The fluid mechanics of natural ventilation  

Microsoft Academic Search

Natural ventilation of buildings is the flow generated by temperature differences and by the wind. Modern buildings have extreme designs with large, tall open plan spaces and large cooling requirements. Natural ventilation offers a means of cooling these buildings and providing good indoor air quality. The essential feature of ventilation is an exchange between an interior space and the external

Paul Linden

1999-01-01

233

Procedures and Standards for Residential Ventilation System  

E-print Network

1 Procedures and Standards for Residential Ventilation System Commissioning: An Annotated and by the California Energy Commission under Pier Contract 500-08-061. Key terms: residential, ventilation.C. and C.P. Wray. 2013. Procedures and Standards for Residential Ventilation System Commissioning

234

Kent Scientific Corporation DUAL MODE VENTILATOR  

E-print Network

Kent Scientific Corporation TOPO DUAL MODE VENTILATOR Operating Manual July 2005 #12;Kent of the labeling on the front of the ventilator may not completely match the digital photographs in this manual.2 Exhaust 8.3 Power Switch & Power Receptacle 9.0 Connecting the Animal to the Ventilator 10.0 Operation 10

235

May 1999 LBNL -42975 ASHRAE'S RESIDENTIAL VENTILATION  

E-print Network

May 1999 LBNL - 42975 ASHRAE'S RESIDENTIAL VENTILATION STANDARD: EXEGESIS OF PROPOSED STANDARD 62 Committee on "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings", SPC 62.2P, approved ASHRAE's first complete standard on residential ventilation for public review

236

WASTE HANDLING BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT  

Microsoft Academic Search

The Waste Handling Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Handling Building (WHB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition

P. A. Kumar

2000-01-01

237

WASTE TREATMENT BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT  

Microsoft Academic Search

The Waste Treatment Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Treatment Building (WTB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition

P. A. Kumar

2000-01-01

238

9 CFR 91.21 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Ventilation. 91.21 Section 91.21 Animals...Vessels and Accommodations § 91.21 Ventilation. Each underdeck compartment on...equipped with a system of mechanical ventilation that will furnish a complete...

2011-01-01

239

46 CFR 168.15-50 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ventilation. 168.15-50 Section 168.15-50... Accommodations § 168.15-50 Ventilation. (a) All quarters must be adequately...the vessel. (b) When mechanical ventilation is provided for sleeping rooms,...

2013-10-01

240

9 CFR 91.21 - Ventilation.  

...2014-01-01 2014-01-01 false Ventilation. 91.21 Section 91.21 Animals...Vessels and Accommodations § 91.21 Ventilation. Each underdeck compartment on...equipped with a system of mechanical ventilation that will furnish a complete...

2014-01-01

241

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ventilation. 194.15-5 Section 194.15-5...Scientific Laboratory § 194.15-5 Ventilation. (a) Operations, reactions...equipped with an independent power exhaust ventilation system which terminates so as to...

2011-10-01

242

9 CFR 91.21 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Ventilation. 91.21 Section 91.21 Animals...Vessels and Accommodations § 91.21 Ventilation. Each underdeck compartment on...equipped with a system of mechanical ventilation that will furnish a complete...

2010-01-01

243

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Ventilation. 194.15-5 Section 194.15-5...Scientific Laboratory § 194.15-5 Ventilation. (a) Operations, reactions...equipped with an independent power exhaust ventilation system which terminates so as to...

2012-10-01

244

9 CFR 91.21 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Ventilation. 91.21 Section 91.21 Animals...Vessels and Accommodations § 91.21 Ventilation. Each underdeck compartment on...equipped with a system of mechanical ventilation that will furnish a complete...

2012-01-01

245

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ventilation. 194.15-5 Section 194.15-5...Scientific Laboratory § 194.15-5 Ventilation. (a) Operations, reactions...equipped with an independent power exhaust ventilation system which terminates so as to...

2013-10-01

246

14 CFR 27.831 - Ventilation.  

...and Space 1 2014-01-01 2014-01-01 false Ventilation. 27.831 Section 27.831 Aeronautics and Space...Construction Personnel and Cargo Accommodations § 27.831 Ventilation. (a) The ventilating system for the pilot and...

2014-01-01

247

9 CFR 91.21 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Ventilation. 91.21 Section 91.21 Animals...Vessels and Accommodations § 91.21 Ventilation. Each underdeck compartment on...equipped with a system of mechanical ventilation that will furnish a complete...

2013-01-01

248

46 CFR 168.15-50 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ventilation. 168.15-50 Section 168.15-50... Accommodations § 168.15-50 Ventilation. (a) All quarters must be adequately...the vessel. (b) When mechanical ventilation is provided for sleeping rooms,...

2010-10-01

249

Formaldehyde Transfer in Residential Energy Recovery Ventilators  

E-print Network

design used in many energy recovery ventilators (ERVs) is designed to transfer heat and moisture betweenFormaldehyde Transfer in Residential Energy Recovery Ventilators Erin L. Hult, Henry Willem and Max and Sherman MH, 2014, Formaldehyde transfer in residential energy recovery ventilators, Building

250

46 CFR 168.15-50 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ventilation. 168.15-50 Section 168.15-50... Accommodations § 168.15-50 Ventilation. (a) All quarters must be adequately...the vessel. (b) When mechanical ventilation is provided for sleeping rooms,...

2011-10-01

251

The effect of changing ventilator settings on indices of ventilation inhomogeneity in small ventilated lungs  

PubMed Central

Background In ventilated newborns the use of multiple breath washout (MBW) techniques for measuring both lung volume and ventilation inhomogeneity (VI) is hampered by the comparatively high dead space fraction. We studied how changes in ventilator settings affected VI indices in this particular population. Methods Using a computer simulation of a uniformly ventilated volume the interaction between VI indices (lung clearance index (LCI), moment ratios (M1/M0, M2/M0, AMDN1, AMDN2) of the washout curve) and tidal volume (VT), dead space (VD) and functional residual capacity (FRC) were calculated. The theoretical results were compared with measurements in 15 ventilated piglets (age <12 h, median weight 1135 g) by increasing the peak inspiratory pressure (PIP). FRC and VI indices were measured by MBW using 0.8% heptafluoropropane as tracer gas. Results The computer simulation showed that the sensitivity of most VI indices to changes in VD/VT and VT/FRC increase, in particular for VD/VT > 0.5. In piglets, the raised PIP caused a significant increase of VT from 15.4 ± 9.5 to 21.9 ± 14.7 (p = 0.003) and of the FRC from 31.6 ± 14.7 mL to 35.0 ± 15.9 mL (p = 0.006), whereas LCI (9.15 ± 0.75 to 8.55 ± 0.74, p = 0.019) and the moment ratios M1/M0, M2/M0 (p < 0.02) decreased significantly. No significant changes were seen in AMDN1 and AMDN2. The within-subject variability of the VI indices (coefficient of variation in brackets) was distinctly higher (LCI (9.8%), M1/M0 (6.6%), M2/M0 (14.6%), AMDN1 (9.1%), AMDN2 (16.3%)) compared to FRC measurements (5.6%). Computer simulations showed that significant changes in VI indices were exclusively caused by changes in VT and FRC and not by an improvement of the homogeneity of alveolar ventilation. Conclusion In small ventilated lungs with a high dead space fraction, indices of VI may be misinterpreted if the changes in ventilator settings are not considered. Computer simulations can help to prevent this misinterpretation. PMID:16916474

Schmalisch, G; Proquitté, H; Roehr, CC; Wauer, RR

2006-01-01

252

Evaluation of Swedish ventilation systems  

Microsoft Academic Search

It is of great importance to the indoor air quality that the ventilation systems, not only directly after taken into operation, operate as they were designed and according to the regulations. The objective of the paper is to show how well the systems satisfy the national regulations after being in operation for several years and what their main defects are.

F. Engdahl

1998-01-01

253

Particle deposition in ventilation ducts  

Microsoft Academic Search

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence

Sippola; Mark R

2002-01-01

254

Preventing Ventilation On Sailboard Skegs  

NASA Technical Reports Server (NTRS)

Design effort undertaken to solve spinout problem plaguing high-performance sailboards. Proposed skeg section designed by use of computer model of pressure field and boundary layer. Prevents ventilation by maintaining attached boundary-layer flow throughout operating environment. Cavitation also avoided by preventing valleys in pressure distribution while skeg operated throughout its range.

Caldwell, Richard A.

1990-01-01

255

Reliability analysis of ventilation systems  

SciTech Connect

This article proposes design parameters and systems analysis procedures for a mine ventilation system which incorporates backup and redundancy in its switching and fan systems in order to optimize the safety and reliability of the overall system. Failure probabilities due to frost buildup and other factors are assessed and several design regimes are comparatively evaluated. Diagrams are included.

Petrov, N.N.; Butorina, O.S.

1987-09-01

256

Simultaneous Multiagent Hyperpolarized 13C Perfusion Imaging  

PubMed Central

Purpose To demonstrate simultaneous hyperpolarization and imaging of three 13C-labeled perfusion MRI contrast agents with dissimilar molecular structures ([13C]urea, [13C]hydroxymethyl cyclopropane, and [13C]t-butanol) and correspondingly variable chemical shifts and physiological characteristics, and to exploit their varying diffusibility for simultaneous measurement of vascular permeability and perfusion in initial preclinical studies. Methods Rapid and efficient dynamic multislice imaging was enabled by a novel pulse sequence incorporating balanced steady state free precession excitation and spectral-spatial readout by multiband frequency encoding, designed for the wide, regular spectral separation of these compounds. We exploited the varying bilayer permeability of these tracers to quantify vascular permeability and perfusion parameters simultaneously, using perfusion modeling methods that were investigated in simulations. “Tripolarized” perfusion MRI methods were applied to initial preclinical studies with differential conditions of vascular permeability, in normal mouse tissues and advanced transgenic mouse prostate tumors. Results Dynamic imaging revealed clear differences among the individual tracer distributions. Computed permeability maps demonstrated differential permeability of brain tissue among the tracers, and tumor perfusion and permeability were both elevated over values expected for normal tissues. Conclusion Tripolarized perfusion MRI provides new molecular imaging measures for specifically monitoring permeability, perfusion, and transport simultaneously in vivo. PMID:24382698

von Morze, Cornelius; Bok, Robert A.; Reed, Galen D.; Ardenkjaer-Larsen, Jan Henrik; Kurhanewicz, John; Vigneron, Daniel B.

2014-01-01

257

Night ventilation control strategies in office buildings  

SciTech Connect

In moderate climates night ventilation is an effective and energy-efficient approach to improve the indoor thermal environment for office buildings during the summer months, especially for heavyweight construction. However, is night ventilation a suitable strategy for office buildings with lightweight construction located in cold climates? In order to answer this question, the whole energy-consumption analysis software EnergyPlus was used to simulate the indoor thermal environment and energy consumption in typical office buildings with night mechanical ventilation in three cities in northern China. The summer outdoor climate data was analyzed, and three typical design days were chosen. The most important factors influencing night ventilation performance such as ventilation rates, ventilation duration, building mass and climatic conditions were evaluated. When night ventilation operation time is closer to active cooling time, the efficiency of night ventilation is higher. With night ventilation rate of 10 ach, the mean radiant temperature of the indoor surface decreased by up to 3.9 C. The longer the duration of operation, the more efficient the night ventilation strategy becomes. The control strategies for three locations are given in the paper. Based on the optimized strategies, the operation consumption and fees are calculated. The results show that more energy is saved in office buildings cooled by a night ventilation system in northern China than ones that do not employ this strategy. (author)

Wang, Zhaojun; Yi, Lingli; Gao, Fusheng [School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China)

2009-10-15

258

Clinical review: Liberation from mechanical ventilation  

PubMed Central

Mechanical ventilation is the defining event of intensive care unit (ICU) management. Although it is a life saving intervention in patients with acute respiratory failure and other disease entities, a major goal of critical care clinicians should be to liberate patients from mechanical ventilation as early as possible to avoid the multitude of complications and risks associated with prolonged unnecessary mechanical ventilation, including ventilator induced lung injury, ventilator associated pneumonia, increased length of ICU and hospital stay, and increased cost of care delivery. This review highlights the recent developments in assessing and testing for readiness of liberation from mechanical ventilation, the etiology of weaning failure, the value of weaning protocols, and a simple practical approach for liberation from mechanical ventilation. PMID:18710593

El-Khatib, Mohamad F; Bou-Khalil, Pierre

2008-01-01

259

Summary of human responses to ventilation  

SciTech Connect

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated risks is seldom possible. The selection of ventilation rates has to be based also on epidemiological research (e.g. Seppanen et al., 1999), laboratory and field experiments (e.g. CEN 1996, Wargocki et al., 2002a) and experience (e.g. ECA 2003). Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated as summarized by Seppdnen (2003). Ventilation may bring indoors harmful substances that deteriorate the indoor environment. Ventilation also affects air and moisture flow through the building envelope and may lead to moisture problems that deteriorate the structures of the building. Ventilation changes the pressure differences over the structures of building and may cause or prevent the infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. Ventilation can be implemented with various methods which may also affect health (e.g. Seppdnen and Fisk, 2002, Wargocki et al., 2002a). In non residential buildings and hot climates, ventilation is often integrated with air-conditioning which makes the operation of ventilation system more complex. As ventilation is used for many purposes its health effects are also various and complex. This paper summarizes the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus of the paper is on office-type working environment and residential buildings. In the industrial premises the problems of air quality are usually more complex and case specific. They are subject to occupational safety legislation and not discussed here.

Seppanen, Olli A.; Fisk, William J.

2004-06-01

260

Effects of imbalance and geometric error on precision grinding machines  

SciTech Connect

To study balancing in grinding, a simple mechanical system was examined. It was essential to study such a well-defined system, as opposed to a large, complex system such as a machining center. The use of a compact, well-defined system enabled easy quantification of the imbalance force input, its phase angle to any geometric decentering, and good understanding of the machine mode shapes. It is important to understand a simple system such as the one I examined given that imbalance is so intimately coupled to machine dynamics. It is possible to extend the results presented here to industrial machines, although that is not part of this work. In addition to the empirical testing, a simple mechanical system to look at how mode shapes, balance, and geometric error interplay to yield spindle error motion was modelled. The results of this model will be presented along with the results from a more global grinding model. The global model, presented at ASPE in November 1996, allows one to examine the effects of changing global machine parameters like stiffness and damping. This geometrically abstract, one-dimensional model will be presented to demonstrate the usefulness of an abstract approach for first-order understanding but it will not be the main focus of this thesis. 19 refs., 36 figs., 10 tables.

Bibler, J.E.

1997-06-01

261

Quantification of the effect of energy imbalance on bodyweight.  

PubMed

Obesity interventions can result in weight loss, but accurate prediction of the bodyweight time course requires properly accounting for dynamic energy imbalances. In this report, we describe a mathematical modelling approach to adult human metabolism that simulates energy expenditure adaptations during weight loss. We also present a web-based simulator for prediction of weight change dynamics. We show that the bodyweight response to a change of energy intake is slow, with half times of about 1 year. Furthermore, adults with greater adiposity have a larger expected weight loss for the same change of energy intake, and to reach their steady-state weight will take longer than it would for those with less initial body fat. Using a population-averaged model, we calculated the energy-balance dynamics corresponding to the development of the US adult obesity epidemic. A small persistent average daily energy imbalance gap between intake and expenditure of about 30 kJ per day underlies the observed average weight gain. However, energy intake must have risen to keep pace with increased expenditure associated with increased weight. The average increase of energy intake needed to sustain the increased weight (the maintenance energy gap) has amounted to about 0·9 MJ per day and quantifies the public health challenge to reverse the obesity epidemic. PMID:21872751

Hall, Kevin D; Sacks, Gary; Chandramohan, Dhruva; Chow, Carson C; Wang, Y Claire; Gortmaker, Steven L; Swinburn, Boyd A

2011-08-27

262

Origin of the imbalance between energy cascade and dissipation in turbulence.  

PubMed

It is shown in direct numerical simulations of homogeneous isotropic non-stationary turbulence that there is a systematic and significant imbalance between the non-linear energy cascade to fine scales and its dissipation. This imbalance stems from the power required to induce or annihilate fine-scale motions in order to change the level of dissipation. The imbalance is present regardless of transfer time-lags and is applicable to a wide range of Reynolds numbers. PMID:25215816

Valente, P C; Onishi, R; da Silva, C B

2014-08-01

263

The measurement of effort–reward imbalance at work: European comparisons  

Microsoft Academic Search

Using comparative data from five countries, this study investigates the psychometric properties of the effort–reward imbalance (ERI) at work model. In this model, chronic work-related stress is identified as non-reciprocity or imbalance between high efforts spent and low rewards received. Health-adverse effects of this imbalance were documented in several prospective and cross-sectional investigations. The internal consistency, discriminant validity and factorial

Johannes Siegrist; Dagmar Starke; Tarani Chandola; Isabelle Godin; Michael Marmot; Isabelle Niedhammer; Richard Peter

2004-01-01

264

Is unilateral antegrade cerebral perfusion equivalent to bilateral cerebral perfusion for patients undergoing aortic arch surgery?  

PubMed

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether unilateral antegrade cerebral perfusion is equivalent to bilateral cerebral plegia for cerebral protection during aortic arch surgery. Altogether 233 papers were found using the reported search, of which 17 presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. These papers documented antegrade selective cerebral perfusion in a total of 3548 patients: bilateral cerebral perfusion in 2949 patients and unilateral perfusion in 599 patients. Both methods of cerebral perfusion resulted in neurological injury rates of <5%, but the period of antegrade cerebral perfusion allowed by bilateral perfusion was significantly higher. While unilateral perfusion allowed around 30-50 min, bilateral perfusion allowed 86 to over 164 min of ASCP with an acceptably low CVA rate. Therefore, we conclude that while both methods are acceptable, once the ASCP time is expected to rise over 40-50 min, bilateral cerebral perfusion is the technique that is best documented to be safe. PMID:18644821

Malvindi, Pietro Giorgio; Scrascia, Giuseppe; Vitale, Nicola

2008-10-01

265

Prevention of ventilator-associated pneumonia.  

PubMed

Ventilator-associated pneumonia is the commonest, yet mostly preventable, infection in mechanically ventilated patients. Successful control of ventilator-associated pneumonia can save hospitalisation cost, and is possible by using a multidisciplinary clinical and administrative approach. The ventilator-associated pneumonia rate should be expressed as the number of ventilator-associated pneumonia days per 1000 ventilator days to take into account the device-utilisation duration for meaningful comparison. Various strategies address the issue, including general infection control measures, body positioning, intubation and mechanical ventilation, oral and gastro-intestinal tract, endotracheal tube, airway pressure, cuff pressure, selective digestive and/or oropharyngeal decontamination, and probiotic or early antibiotic treatment, as well as overall administration at a policy level. The rationale and controversy of these approaches are discussed in this article. The authors suggest that all units treating mechanically ventilated patients should have a ventilator-associated pneumonia prevention protocol in place, and ventilator-associated pneumonia should be seriously considered as a key performance indicator in local intensive care units. PMID:25593193

Lau, A Cw; So, H M; Tang, S L; Yeung, A; Lam, S M; Yan, W W

2015-02-01

266

Alterations in atrial perfusion during atrial fibrillation.  

PubMed

Left atrial (LA) perfusion during disease states has been a topic of much interest, because the clinical implications and detrimental effects of lack of blood flow to the atria are numerous. In the chronic setting, changes in perfusion may lead to LA ischaemia and structural remodelling, a factor implicated in the self-perpetuation of chronic atrial fibrillation (AF). The association between AF and altered LA perfusion has been studied, but a direct causal association between perfusion changes and AF has not been established. A comprehensive literature search of Medline, Embase and Google Scholar databases was conducted from 1960 to February 2014. We systematically analysed reference lists of physiological articles and reviews for other possibly relevant studies. The aim of this review is to provide a comprehensive discussion of the AF-mediated changes in LA perfusion and the potential mechanisms underlying the alterations in coronary flow to the LA in this setting. In addition, we discuss the clinical contexts in which changes in LA perfusion may be relevant. Finally, this article highlights the need for longitudinal studies of AF that would elucidate the changes in LA perfusion resulting from chronic AF and lead to advancements in effective treatments to prevent progression of this disease. PMID:25063838

Pacchia, Christina F; Dosdall, Derek J; Ranjan, Ravi; DiBella, Edward

2014-10-01

267

Ventilation effects on combustion products.  

PubMed

The effects of fire ventilation on combustion products are expressed in terms of relationship between concentration of products and equivalence ratio, phi. For well-ventilated fires, phi < 1.0, where mostly heat and products of complete combustion (such as CO2 and water) are generated. For ventilation-controlled fires, phi > 1.0, where mostly products of incomplete combustion are generated with very high concentrations in a transition region for phi between 1.0 and 3.5. The high concentrations of the products of incomplete combustion are dangerous to life and property. For halogenated materials, this condition occurs for phi < 1.0. The non-flaming region for fires is found to exist for phi > 3.5. Correlations have been developed for the prediction of concentrations of products at various phi values for the assessment of combustion toxicity and smoke damage hazards by zone fire models, such as Hazard 1. The correlations show good agreement with the measured concentrations. The concentrations of the products of incomplete combustion depend on the chemical structures of the materials. For the same phi values, the carbon monoxide concentrations are higher for materials with oxygen atoms in the structure, whereas smoke concentrations are higher for materials with carbon and hydrogen atoms in the structure. The results of the study suggest that it is necessary to examine the combustion behaviour of advanced materials for use in aircraft and other critical applications at various phi values, along with the toxicity experiments. PMID:9016749

Tewarson, A

1996-12-31

268

Effects of surfactant depletion on regional pulmonary metabolic activity during mechanical ventilation  

PubMed Central

Inflammation during mechanical ventilation is thought to depend on regional mechanical stress. This can be produced by concentration of stresses and cyclic recruitment in low-aeration dependent lung. Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) allows for noninvasive assessment of regional metabolic activity, an index of neutrophilic inflammation. We tested the hypothesis that, during mechanical ventilation, surfactant-depleted low-aeration lung regions present increased regional 18F-FDG uptake suggestive of in vivo increased regional metabolic activity and inflammation. Sheep underwent unilateral saline lung lavage and were ventilated supine for 4 h (positive end-expiratory pressure = 10 cmH2O, tidal volume adjusted to plateau pressure = 30 cmH2O). We used PET scans of injected 13N-nitrogen to compute regional perfusion and ventilation and injected 18F-FDG to calculate 18F-FDG uptake rate. Regional aeration was quantified with transmission scans. Whole lung 18F-FDG uptake was approximately two times higher in lavaged than in nonlavaged lungs (2.9 ± 0.6 vs. 1.5 ± 0.3 10?3/min; P < 0.05). The increased 18F-FDG uptake was topographically heterogeneous and highest in dependent low-aeration regions (gas fraction 10–50%, P < 0.001), even after correction for lung density and wet-to-dry lung ratios. 18F-FDG uptake in low-aeration regions of lavaged lungs was higher than that in low-aeration regions of nonlavaged lungs (P < 0.05). This occurred despite lower perfusion and ventilation to dependent regions in lavaged than nonlavaged lungs (P < 0.001). In contrast, 18F-FDG uptake in normally aerated regions was low and similar between lungs. Surfactant depletion produces increased and heterogeneously distributed pulmonary 18F-FDG uptake after 4 h of supine mechanical ventilation. Metabolic activity is highest in poorly aerated dependent regions, suggesting local increased inflammation. PMID:21799132

de Prost, Nicolas; Costa, Eduardo L.; Wellman, Tyler; Musch, Guido; Winkler, Tilo; Tucci, Mauro R.; Harris, R. Scott; Venegas, Jose G.

2011-01-01

269

Cyclooxygenase blockade (COB) attenuates ethanol-induced pulmonary vasoconstriction in perfused rat lungs  

SciTech Connect

Ethanol causes pulmonary vasoconstriction and vascular leak by obscure mechanisms. In lambs, COB with indomethacin (Indo) or meclofenamate (Meclo) block ethanol's circulatory effects. To test for these effects in rats, in-situ, ventilated, Krebs-Henselheit perfused (constant flow) lungs were studied in 6 groups: ethanol (ETOH) and perfusate controls; ETOH/Meclo, 0.5 and 1 mg/kg, IV; ETOH/Indo, 0.5 and 1 mg/kg, IV, given 30 minutes before study. They measured mean pulmonary arterial pressure (PAP), peak inspiratory pressure (PIP) and edema, indexed by reservoir weight change (RW), then by tracheal froth ( death'). ETOH doses (0.5, 1.3 and 2.2gm) were infused into the perfusate (60 ml). Data were analyzed by ANOVA and X{sup 2}; n = 9 in each group. PAP differed by treatment, by drug/dose, and by dose/treatment interactions; PIP, RW change, and death' were attenuated. Data show that COB lessens the vascular and edema effects of moderate dose ETOH, which larger ETOH doses override.

Drummond, W.H.; Lyles, D. (Univ. of Florida, Gainesville (United States))

1990-02-26

270

Calculation of the Respiratory Modulation of the Photoplethysmogram (DPOP) Incorporating a Correction for Low Perfusion  

PubMed Central

DPOP quantifies respiratory modulations in the photoplethysmogram. It has been proposed as a noninvasive surrogate for pulse pressure variation (PPV) used in the prediction of the response to volume expansion in hypovolemic patients. The correlation between DPOP and PPV may degrade due to low perfusion effects. We implemented an automated DPOP algorithm with an optional correction for low perfusion. These two algorithm variants (DPOPa and DPOPb) were tested on data from 20 mechanically ventilated OR patients split into a benign “stable region” subset and a whole record “global set.” Strong correlation was found between DPOP and PPV for both algorithms when applied to the stable data set: R = 0.83/0.85 for DPOPa/DPOPb. However, a marked improvement was found when applying the low perfusion correction to the global data set: R = 0.47/0.73 for DPOPa/DPOPb. Sensitivities, Specificities, and AUCs were 0.86, 0.70, and 0.88 for DPOPa/stable region; 0.89, 0.82, and 0.92 for DPOPb/stable region; 0.81, 0.61, and 0.73 for DPOPa/global region; 0.83, 0.76, and 0.86 for DPOPb/global region. An improvement was found in all results across both data sets when using the DPOPb algorithm. Further, DPOPb showed marked improvements, both in terms of its values, and correlation with PPV, for signals exhibiting low percent modulations. PMID:25177348

Addison, Paul S.; Wang, Rui; McGonigle, Scott J.; Bergese, Sergio D.

2014-01-01

271

Particle deposition in ventilation ducts  

SciTech Connect

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 {micro}m were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the experimental measurements was applied to evaluate particle losses in supply and return duct runs. Model results suggest that duct losses are negligible for particle sizes less than 1 {micro}m and complete for particle sizes greater than 50 {micro}m. Deposition to insulated ducts, horizontal duct floors and bends are predicted to control losses in duct systems. When combined with models for HVAC filtration and deposition to indoor surfaces to predict the ultimate fates of particles within buildings, these results suggest that ventilation ducts play only a small role in determining indoor particle concentrations, especially when HVAC filtration is present. However, the measured and modeled particle deposition rates are expected to be important for ventilation system contamination.

Sippola, Mark R.

2002-09-01

272

CFD applications in tunnel ventilation analysis  

SciTech Connect

Longitudinal ventilation systems in transit and rail tunnels are typically analyzed by one dimensional ventilation network simulation models, such as the Subway Environment Simulation (SES) program. However, in recent years computational fluid dynamics (CFD) modeling has been utilized in conjunction with one-dimensional ventilation network programs to study ventilation systems for large volume spaces such as transit stations and rail overbuilds, as well as for vehicular tunnels. CFD uses numerical methods to simulate complex fluid flow phenomena in three dimensions to predict the distribution of velocity, pressure, temperature, concentration, and other relevant variables throughout the volume. This paper presents an overview of CFD study results from emergency ventilation analysis for a transit station and both emergency ventilation and diesel emissions analysis for a rail overbuild.

Ray, R.E. Jr.; Zigh, A.

1999-07-01

273

CONFIDENTIAL: DO NOT QUOTE 1 Equivalence in Ventilation and  

E-print Network

CONFIDENTIAL: DO NOT QUOTE 1 Equivalence in Ventilation and Indoor Air Quality M. H. Sherman, I ventilate buildings to provide acceptable indoor air quality (IAQ). Ventilation standards (such as American ventilation rates without taking into account the impact of those rates on IAQ. Innovative ventilation

274

Colombian late cretaceous tropical planktonic foraminifera: Redressing the imbalance  

SciTech Connect

Recent work involving Late Cretaceous planktonic foraminifera has concentrated on European and other areas in the Northern Hemisphere. Many of the biostratigraphical and evolutionary models reflect this geographical restriction and ignore earlier studies from tropical areas. In 1955 Rolando Gandolfi described many new species and subspecies from Colombia and provided a different view of the evolutionary development of planktonic foraminifera. A re-examination of the Gandolfi type collection using Scanning Electron Micrography (Environmental Chamber technique) integrated with Colombian well samples from onshore Guajira area, Middle and Upper Magdalena Valley and Putumayo Basin has given a new view into the evolutionary development of Late Cretaceous planktonic foraminifera. This has enabled a modified globigerine Late Cretaceous biostratigraphy to be constructed for Colombia. This work redresses the imbalance between studies of tropical and northern high latitude Late Cretaceous planktonic foraminifera and provides an insight into the paleoenvironmental and paleoclimatological factors influencing the Colombian region at the time.

McCarthy, L.D.

1993-02-01

275

Microbial imbalance and intestinal pathologies: connections and contributions  

PubMed Central

Microbiome analysis has identified a state of microbial imbalance (dysbiosis) in patients with chronic intestinal inflammation and colorectal cancer. The bacterial phylum Proteobacteria is often overrepresented in these individuals, with Escherichia coli being the most prevalent species. It is clear that a complex interplay between the host, bacteria and bacterial genes is implicated in the development of these intestinal diseases. Understanding the basic elements of these interactions could have important implications for disease detection and management. Recent studies have revealed that E. coli utilizes a complex arsenal of virulence factors to colonize and persist in the intestine. Some of these virulence factors, such as the genotoxin colibactin, were found to promote colorectal cancer in experimental models. In this Review, we summarize key features of the dysbiotic states associated with chronic intestinal inflammation and colorectal cancer, and discuss how the dysregulated interplay between host and bacteria could favor the emergence of E. coli with pathological traits implicated in these pathologies. PMID:25256712

Yang, Ye; Jobin, Christian

2014-01-01

276

Evaluating the physiological significance of respiratory sinus arrhythmia: looking beyond ventilation–perfusion efficiency  

PubMed Central

We conducted a theoretical study of the physiological significance of respiratory sinus arrhythmia (RSA), a phenomenon used as an index of cardiac vagal tone and wellbeing, whereby the heart rate (HR) increases during inspiration and decreases during expiration. We first tested the hypothesis that RSA improves gas exchange efficiency but found that although gas exchange efficiency improved with slow and deep breathing and with increased mean heart rate, this was unrelated to RSA. We then formulated and tested a new hypothesis: that RSA minimizes the work done by the heart while maintaining physiological levels of arterial carbon dioxide. We tested the new hypothesis using two methods. First, the HR for which the work is minimized was calculated using techniques from optimal control theory. This calculation was done on simplified models that we derived from a previously published model of gas exchange in mammals. We found that the calculated HR was remarkably similar to RSA and that this became more profound under slow and deep breathing. Second, the HR was prescribed and the work done by the heart was calculated by conducting a series of numerical experiments on the previously published gas exchange model. We found that cardiac work was minimized for RSA-like HR functions, most profoundly under slow and deep breathing. These findings provide novel insights into potential reasons for and benefits of RSA under physiological conditions. PMID:22289913

Ben-Tal, A; Shamailov, S S; Paton, J F R

2012-01-01

277

"Molecular rulers" for calibrating phenotypic effects of telomere imbalance  

PubMed Central

As a result of the increasing use of genome wide telomere screening, it has become evident that a significant proportion of people with idiopathic mental retardation have subtle abnormalities involving the telomeres of human chromosomes. However, during the course of these studies, there have also been telomeric imbalances identified in normal people that are not associated with any apparent phenotype. We have begun to scrutinise cases from both of these groups by determining the extent of the duplication or deletion associated with the imbalance. Five cases were examined where the telomere rearrangement resulted in trisomy for the 16p telomere. The size of the trisomic segment ranged from ?4-7 Mb and the phenotype included mental and growth retardation, brain malformations, heart defects, cleft palate, pancreatic insufficiency, genitourinary abnormalities, and dysmorphic features. Three cases with telomeric deletions without apparent phenotypic effects were also examined, one from 10q and two from 17p. All three deletions were inherited from a phenotypically normal parent carrying the same deletion, thus without apparent phenotypic effect. The largest deletion among these cases was ?600 kb on 17p. Similar studies are necessary for all telomeric regions to differentiate between those telomeric rearrangements that are pathogenic and those that are benign variants. Towards this goal, we are developing "molecular rulers" that incorporate multiple clones at each telomere that span the most distal 5 Mb region. While telomere screening has enabled the identification of telomere rearrangements, the use of molecular rulers will allow better phenotype prediction and prognosis related to these findings. PMID:12362030

Martin, C; Waggoner, D; Wong, A; Uhrig, S; Roseberry, J; Hedrick, J; Pack, S; Russell, K; Zackai, E; Dobyns, W; Ledbetter, D

2002-01-01

278

Multi-delay Arterial Spin Labeling Perfusion MRI in Moyamoya Disease – Comparison with CT Perfusion Imaging  

PubMed Central

Purpose To present a multi-delay multi-parametric pseudo-continuous ASL (pCASL) protocol that offers simultaneous measurements of cerebral blood flow (CBF), arterial transit time (ATT) and arterial cerebral blood volume (aCBV) and to evaluate its accuracy by comparison with CT perfusion in moyamoya disease. Materials and Methods A 4 post-labeling delay (PLD) pCASL protocol was applied on 17 patients with moyamoya disease who also underwent CT perfusion imaging. ATT was estimated using the multi-delay protocol and included in the calculation of CBF. ASL and CT perfusion images were rated for lesion severity/conspicuity. Pearson correlation coefficients were calculated across voxels between the two modalities in grey and white matter of each subject respectively and between normalized mean values of ASL and CT perfusion measures in major vascular territories. Results Significant associations between ASL and CT perfusion were detected using subjective ratings, voxel-wise analysis in grey and white matter and region of interest (ROI) based analysis of normalized mean perfusion. The correlation between ASL CBF and CT perfusion was improved using the multi-delay pCASL protocol compared to CBF acquired at a single PLD of 2 s (p<0.05). Conclusion There is a correlation between perfusion data from ASL and CT perfusion imaging in patients with moyamoya disease. Multi-delay ASL can improve CBF quantification, which could be a prognostic imaging biomarker in patients with moyamoya disease. PMID:24557051

Wang, Rui; Yu, Songlin; Alger, Jeffry R.; Zuo, Zhentao; Chen, Juan; Wang, Rong; An, Jing; Wang, Bo; Zhao, Jizong; Xue, Rong; Wang, Danny JJ

2014-01-01

279

Uptake of exogenous spermidine by rat lungs perfused in situ  

SciTech Connect

Uptake of the polyamine spermidine (SPD) from the pulmonary circulation was characterized by using ventilated rat lungs perfused in situ with Krebs-Henseleit-bicarbonate buffer containing 4.5% bovine serum albumin, 5.6 mM glucose, and 20 amino acids at plasma levels. (/sup 14/C)SPD was accumulated by the lungs in a time- and concentration-dependent manner. The pathway of SPD uptake exhibited saturation kinetics with an apparent K/sub m/ in the range of 1 ..mu..M and a V/sub max/ of 450-540 pmol/g lung min. SPD uptake was inhibited by the naturally occurring polyamines putrescine and spermine (SPM) and by the inhibitor of polyamine synthesis, methyglyoxal bis(guanylhydrazone) (MGBG). Inhibition of SPD uptake by SPM followed competitive kinetics; although MGBG was also a competitive inhibitor of SPD uptake, MGBG was less effective than SPM. These observations indicate that SPD is taken up from the pulmonary circulation by a carrier-mediated pathway that is inhibited by other natural polyamines and by MGBG and exhibits by other natural polyamines and by MGBG and exhibits substrate affinity in the range of plasma SPD concentrations.

Rannels, D.E.; Addison, J.L.

1987-01-01

280

Patterns of pulmonary perfusion scans in normal subjects  

SciTech Connect

A vital factor conditioning the usage of the pulmonary perfusion (Q) scan in the evaluation of patients suspected of pulmonary embolism is the prevalence of abnormal Q scans in subjects free of cardiopulmonary disease. Because this prevalence has not been well defined, we performed Q scans in 80 nonsmoking subjects 18 to 29 yr of age having no known active cardiopulmonary disease. Each subject underwent a history, physical examination, electrocardiogram, spirometry, and PA chest roentgenogram, followed by a 6-view Q scan. Two subjects in whom a Q defect was suspected underwent a /sup 133/Xe equilibrium-washout ventilation (V) scan. All Q scans were interpreted blindly and independently by 2 experienced readers. Seventy-nine of the 80 Q scans were read as normal. No subject demonstrated a lobar or segmental defect. One of the 80 subjects, who had a mild pectus excavatum, had a left upper lobe subsegmental defect, which was not seen on the V scan. Based on the statistical analysis of these data, no more than 3.68% of normal nonsmoking persons in this age group may have a lobar or segmental Q scan defect and no more than 6.77% may have a subsegmental defect (with 95% confidence). Therefore, our study indicated that Q scan defects, particularly lobar or segmental, are rarely present among normal nonsmokers in this age group.

Wallace, J.M.; Moser, K.M.; Hartman, M.T.; Ashburn, W.L.

1981-01-01

281

Ventilation of sheep and goat barns.  

PubMed

Good ventilation is an important part of any livestock housing system. It may be accomplished by either natural or mechanical means. Generally, except for buildings that must be kept at warm, nonfluctuating temperatures, naturally ventilated cold housing is satisfactory for sheep and goats provided it is dry and draft-free in pen and resting areas, and air exchange is taking place at a rate high enough to remove moisture, gases, and airborne disease organisms from the building. Understanding the importance of site location, building orientation, and principles of ventilation design increases the likelihood of successful barn ventilation. PMID:2245366

Collins, E R

1990-11-01

282

Ventilation and Work Performance in Office Work  

SciTech Connect

Outdoor air ventilation rates vary considerably between and within buildings. The purpose of this study was to evaluate the potential work performance benefits of increased ventilation. They analyzed the literature relating work performance with ventilation rate and employed statistical analyses with weighting factors to combine the results of different studies. The studies included in the review assessed performance of various tasks in laboratory experiments and measured performance at work in real buildings. Almost all studies found increases in performance with higher ventilation rates. The studies indicated typically a 1-3% improvement in average performance per 10 L/s-person increase in outdoor air ventilation rate. The performance increase per unit increase in ventilation was bigger with ventilation rates below 20 L/s-person and almost negligible with ventilation rates over 45 L/s-person. The performance increase was statistically significant with increased ventilation rates up to 15 L/s-person with 95% CI and up to 17 L/s-person with 90% CI.

Seppanen, Olli; Fisk, William J.; Lei, Q.H.

2005-07-01

283

High-frequency ventilation and conventional mechanical ventilation in newborn babies with respiratory distress syndrome: A prospective, randomized trial  

Microsoft Academic Search

Objective. Morbidity and mortality remain high amongst babies ventilated for a respiratory distress syndrome (RDS). Whether newly developed ventilators allowing high frequency ventilation such as high frequen- cy flow interrupted ventilation (HFFIV) could decrease the morbidity and the mortality was investigated in a ran- domized study. Design: Preterm babies weighing < 1800 g suffering from RDS and ventilated by conventional

A. Pardou; D. Vermeylen; M. F. Muller; D. Detemmerman

1993-01-01

284

Interactive Simulation System for Artificial Ventilation on the Internet: Virtual Ventilator  

Microsoft Academic Search

Objective. To develop an interactive simulation system “virtual ventilator” that demonstrates the dynamics of pressure and flow in the respiratory system under the combination of spontaneous breathing, ventilation modes, and ventilator options. The simulation system was designed to be used by unexperienced health care professionals as a self-training tool. Methods. The system consists of a simulation controller and three modules:

Akihiro Takeuchi; Tadashi Abe; Minoru Hirose; Koichi Kamioka; Atsushi Hamada; Noriaki Ikeda

2004-01-01

285

Genome-wide Detection of Allelic Imbalance Using Human SNPs and High-density DNA Arrays  

Microsoft Academic Search

Most human cancers are characterized by genomic instability, the accumulation of multiple genetic alterations and allelic imbalance throughout the genome. Loss of heterozygosity (LOH) is a common form of allelic imbalance and the detection of LOH has been used to identify genomic regions that harbor tumor suppressor genes and to characterize tumor stages and progression. Here we describe the use

Rui Mei; Patricia C. Galipeau; Cynthia Prass; Anthony Berno; Ghassan Ghandour; Nila Patil; Roger K. Wolff; Mark S. Chee; Brian J. Reid; David J. Lockhart

2000-01-01

286

Glomerular filtration in the isolated perfused kidney  

Microsoft Academic Search

Glomerular hemodynamics were studied of isolated perfused kidneys of 12-wk-old normotensive (NR) and spontaneously hypertensive (SHR) rats, using Pluronic F108 (BASF, Wyandotte, MI, USA) as a plasma expander. Glomerular filtration rate (GFR), proximal tubular hydrostatic pressure (PT) and glomerular capillary hydrostatic pressure (PGC) were approximately linearly related with renal perfusion pressure.PGC measured directly by micropuncture was comparable toPGC calculated from

H. M. Brink; W. M. Moons; J. F. G. Slegers

1983-01-01

287

Pancreas transplants: Evaluation using perfusion scintigraphy  

SciTech Connect

To determine the value of scintigraphic perfusion studies in evaluating pancreas transplant patients, we reviewed 56 of these studies in 22 patients who had 27 transplants. Seventeen patients underwent two or more studies. The perfusion studies were performed with 20 mCi (740 MBq) of 99mTc-DTPA injected as a bolus followed by eight to 16 serial 2-sec images and a 500,000-count immediate static image. Images were evaluated for (1) the time and intensity of pancreatic peak radioactivity relative to the time and intensity of the iliac arterial peak; (2) relative pancreatic to iliac arterial intensity on the static image; and (3) size, homogeneity, and definition of the pancreas. Clinical diagnoses at the time of scintigraphy of normal function (n = 36), rejection (n = 13), pancreatitis (n = 6), or arterial thrombosis (n = 1) were based on insulin requirement, urine amylase, serum glucose, serum amylase, response to therapy, cultures, CT, MR, sonography, scintigraphy with 67Ga or 111In-WBCs, percutaneous drainage results, angiography, surgery, and pathologic examination of resected transplants. Three 99mTc-DTPA perfusion studies showed no pancreatic perfusion, four showed decreasing perfusion on serial studies, and five showed progressive loss of definition of the pancreas on serial studies. Of the three patients with no detectable perfusion, one had a normally functioning transplant, one had arterial thrombosis with transplant infarction, and one had severe rejection with minimal function. Decreasing perfusion was associated with rejection in three patients and pancreatitis in one. Decreasing definition was seen in four patients with rejection and one with pancreatitis. We conclude that perfusion scintigraphy is useful, primarily when performed serially, although nonspecific for evaluating pancreas transplants.

Kuni, C.C.; du Cret, R.P.; Boudreau, R.J.

1989-07-01

288

Interactive Visual Analysis of Perfusion Data  

Microsoft Academic Search

Abstract—Perfusion data are dynamic,medical image data which characterize the regional blood flow in human,tissue. These data have a great potential in medical diagnosis, since diseases can be better discriminated and detected at an earlier stage compared to static image data. The wide-spread use of perfusion data is hampered by the lack of efficient evaluation methods. For each voxel, a time-intensity

Steffen Oeltze; Helmut Doleisch; Helwig Hauser; Philipp Muigg; Bernhard Preim

2007-01-01

289

Soluble guanylyl cyclase contributes to ventilator-induced lung injury in mice  

PubMed Central

High tidal volume (HVT) ventilation causes pulmonary endothelial barrier dysfunction. HVT ventilation also increases lung nitric oxide (NO) and cGMP. NO contributes to HVT lung injury, but the role of cGMP is unknown. In the current study, ventilation of isolated C57BL/6 mouse lungs increased perfusate cGMP as a function of VT. Ventilation with 20 ml/kg VT for 80 min increased the filtration coefficient (Kf), an index of vascular permeability. The increased cGMP and Kf caused by HVT were attenuated by nitric oxide synthase (NOS) inhibition and in lungs from endothelial NOS knockout mice. Inhibition of soluble guanylyl cyclase (sGC) in wild-type lungs (10 ?M ODQ) also blocked cGMP generation and inhibited the increase in Kf, suggesting an injurious role for sGC-derived cGMP. sGC inhibition also attenuated lung Evans blue dye albumin extravasation and wet-to-dry weight ratio in an anesthetized mouse model of HVT injury. Additional activation of sGC (1.5 ?M BAY 41-2272) in isolated lungs at 40 min increased cGMP production and Kf in lungs ventilated with 15 ml/kg VT. HVT endothelial barrier dysfunction was attenuated with a nonspecific phosphodiesterase (PDE) inhibitor (100 ?M IBMX) as well as an inhibitor (10 ?M BAY 60-7550) specific for the cGMP-stimulated PDE2A. Concordantly, we found a VT-dependent increase in lung cAMP hydrolytic activity and PDE2A protein expression with a decrease in lung cAMP concentration that was blocked by BAY 60-7550. We conclude that HVT-induced endothelial barrier dysfunction resulted from a simultaneous increase in NO/sGC-derived cGMP and PDE2A expression causing decreased cAMP. PMID:18849438

Schmidt, Eric P.; Damarla, Mahendra; Rentsendorj, Otgonchimeg; Servinsky, Laura E.; Zhu, Bing; Moldobaeva, Aigul; Gonzalez, Alfredo; Hassoun, Paul M.; Pearse, David B.

2008-01-01

290

Perfusion visualization and analysis for pulmonary embolism  

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

291

Regional Lung Derecruitment and Inflammation during 16 Hours of Mechanical Ventilation in Supine Healthy Sheep  

PubMed Central

Background Lung derecruitment is common during general anesthesia. Mechanical ventilation with physiological tidal volumes could magnify derecruitment, and produce lung dysfunction and inflammation. We used Positron Emission Tomography to study the process of derecruitment in normal lungs ventilated for 16 h, and the corresponding changes in regional lung perfusion and inflammation. Methods Six anesthetized supine sheep were ventilated with VT = 8mL/kg and positive end-expiratory pressure = 0. Transmission scans were obtained at 2-h intervals to assess regional aeration. Emission scans were acquired at baseline and after 16 h for the tracers: (a) 18F-fluorodeoxyglucose to evaluate lung inflammation, and (b) 13NN to calculate regional perfusion and shunt fraction. Results Gas fraction decreased from baseline to 16 h in dorsal (0.31 ± 0.13 to 0.14 ± 0.12, P < 0.01) but not ventral regions (0.61 ± 0.03 to 0.63 ± 0.07, P = NS), with time constants of 1.5-44.6 h. Whereas the vertical distribution of relative perfusion did not change from baseline to 16 h, shunt increased in dorsal regions (0.34 ± 0.23 to 0.63 ± 0.35, P < 0.01). The average pulmonary net 18F-fluorodeoxyglucose uptake rate in six regions of interest along the ventral-dorsal direction increased from 3.4 ± 1.4·10-3min-1 at baseline to 4.1 ± 1.5·10-3min-1 after 16 h (P < 0.01), and the corresponding average regions of interest 18F-fluorodeoxyglucose phosphorylation rate increased from 2.0 ± 0.2·10-2min-1 to 2.5 ± 0.2·10-2min-1 (P < 0.01). Conclusions In normal lungs mechanically ventilated without positive end-expiratory pressure, loss of aeration occurs continuously for several hours and is preferentially localized to dorsal regions. Progressive lung derecruitment was associated with increased regional shunt, implying an insufficient hypoxic pulmonary vasoconstriction. The increased pulmonary net uptake and phosphorylation rates of 18F-fluorodeoxyglucose suggest incipient inflammation in these initially normal lungs. PMID:23535501

Tucci, Mauro R.; Costa, Eduardo L.V.; Wellman, Tyler J.; Musch, Guido; Winkler, Tilo; Harris, R. Scott; Venegas, Jose G.; Amato, Marcelo B. P.; Vidal Melo, Marcos F.

2014-01-01

292

21 CFR 868.5955 - Intermittent mandatory ventilation attachment.  

Code of Federal Regulations, 2011 CFR

... (a) Identification. An intermittent mandatory ventilation (IMV) attachment is a device attached to a mechanical ventilator that allows spontaneous breathing by a patient while providing mechanical ventilation at a preset rate. (b)...

2011-04-01

293

Evaluation of Existing Technologies for Meeting Residential Ventilation  

E-print Network

LBNL-59998 Evaluation of Existing Technologies for Meeting Residential Ventilation Requirements Ventilation Requirements and Distribution System Research for 2008 Building Efficiency Standards Task 3.2 Evaluation of Existing Technologies for Meeting Residential Ventilation Requirements Prepared in Support

294

Commissioning Residential Ventilation Systems: A Combined Assessment of  

E-print Network

Commissioning Residential Ventilation Systems: A Combined Assessment of Energy and Air Quality ventilation systems are being installed in new California homes. Few measurements are available of commissioning residential whole- house ventilation systems that are intended to comply

295

46 CFR 190.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2011 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...storerooms, and machinery spaces and for closing all doorways, ventilators, and annular spaces around funnels and other openings...

2011-10-01

296

21 CFR 868.5925 - Powered emergency ventilator.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Powered emergency ventilator. 868.5925 Section 868.5925...Devices § 868.5925 Powered emergency ventilator. (a) Identification. A powered emergency ventilator is a demand valve or inhalator...

2012-04-01

297

46 CFR 72.15-15 - Ventilation for closed spaces.  

Code of Federal Regulations, 2012 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...machinery and cargo spaces and for closing all doorways, ventilators and annular spaces around funnels and other openings...

2012-10-01

298

46 CFR 190.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2013 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...storerooms, and machinery spaces and for closing all doorways, ventilators, and annular spaces around funnels and other openings...

2013-10-01

299

21 CFR 868.5955 - Intermittent mandatory ventilation attachment.  

... (a) Identification. An intermittent mandatory ventilation (IMV) attachment is a device attached to a mechanical ventilator that allows spontaneous breathing by a patient while providing mechanical ventilation at a preset rate. (b)...

2014-04-01

300

21 CFR 868.5925 - Powered emergency ventilator.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Powered emergency ventilator. 868.5925 Section 868.5925...Devices § 868.5925 Powered emergency ventilator. (a) Identification. A powered emergency ventilator is a demand valve or inhalator...

2013-04-01

301

21 CFR 868.5955 - Intermittent mandatory ventilation attachment.  

Code of Federal Regulations, 2012 CFR

... (a) Identification. An intermittent mandatory ventilation (IMV) attachment is a device attached to a mechanical ventilator that allows spontaneous breathing by a patient while providing mechanical ventilation at a preset rate. (b)...

2012-04-01

302

21 CFR 868.5955 - Intermittent mandatory ventilation attachment.  

Code of Federal Regulations, 2013 CFR

... (a) Identification. An intermittent mandatory ventilation (IMV) attachment is a device attached to a mechanical ventilator that allows spontaneous breathing by a patient while providing mechanical ventilation at a preset rate. (b)...

2013-04-01

303

21 CFR 868.5935 - External negative pressure ventilator.  

...false External negative pressure ventilator. 868.5935 Section 868.5935...5935 External negative pressure ventilator. (a) Identification. An external negative pressure ventilator (e.g., iron lung,...

2014-04-01

304

46 CFR 190.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2012 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...storerooms, and machinery spaces and for closing all doorways, ventilators, and annular spaces around funnels and other openings...

2012-10-01

305

46 CFR 72.15-15 - Ventilation for closed spaces.  

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...machinery and cargo spaces and for closing all doorways, ventilators and annular spaces around funnels and other openings...

2014-10-01

306

21 CFR 868.5935 - External negative pressure ventilator.  

Code of Federal Regulations, 2011 CFR

...false External negative pressure ventilator. 868.5935 Section 868.5935...5935 External negative pressure ventilator. (a) Identification. An external negative pressure ventilator (e.g., iron lung,...

2011-04-01

307

21 CFR 868.5925 - Powered emergency ventilator.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Powered emergency ventilator. 868.5925 Section 868.5925...Devices § 868.5925 Powered emergency ventilator. (a) Identification. A powered emergency ventilator is a demand valve or inhalator...

2011-04-01

308

46 CFR 72.15-15 - Ventilation for closed spaces.  

Code of Federal Regulations, 2010 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...machinery and cargo spaces and for closing all doorways, ventilators and annular spaces around funnels and other openings...

2010-10-01

309

21 CFR 868.5925 - Powered emergency ventilator.  

...2014-04-01 false Powered emergency ventilator. 868.5925 Section 868.5925...Devices § 868.5925 Powered emergency ventilator. (a) Identification. A powered emergency ventilator is a demand valve or inhalator...

2014-04-01

310

46 CFR 72.15-15 - Ventilation for closed spaces.  

Code of Federal Regulations, 2011 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...machinery and cargo spaces and for closing all doorways, ventilators and annular spaces around funnels and other openings...

2011-10-01

311

21 CFR 868.5935 - External negative pressure ventilator.  

Code of Federal Regulations, 2010 CFR

...false External negative pressure ventilator. 868.5935 Section 868.5935...5935 External negative pressure ventilator. (a) Identification. An external negative pressure ventilator (e.g., iron lung,...

2010-04-01

312

21 CFR 868.5935 - External negative pressure ventilator.  

Code of Federal Regulations, 2012 CFR

...false External negative pressure ventilator. 868.5935 Section 868.5935...5935 External negative pressure ventilator. (a) Identification. An external negative pressure ventilator (e.g., iron lung,...

2012-04-01

313

21 CFR 868.5925 - Powered emergency ventilator.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Powered emergency ventilator. 868.5925 Section 868.5925...Devices § 868.5925 Powered emergency ventilator. (a) Identification. A powered emergency ventilator is a demand valve or inhalator...

2010-04-01

314

46 CFR 72.15-15 - Ventilation for closed spaces.  

Code of Federal Regulations, 2013 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...machinery and cargo spaces and for closing all doorways, ventilators and annular spaces around funnels and other openings...

2013-10-01

315

46 CFR 190.15-10 - Ventilation for closed spaces.  

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...storerooms, and machinery spaces and for closing all doorways, ventilators, and annular spaces around funnels and other openings...

2014-10-01

316

21 CFR 868.5935 - External negative pressure ventilator.  

Code of Federal Regulations, 2013 CFR

...false External negative pressure ventilator. 868.5935 Section 868.5935...5935 External negative pressure ventilator. (a) Identification. An external negative pressure ventilator (e.g., iron lung,...

2013-04-01

317

HVAC EFFICIENCY BUSINESS CASE DEMAND CONTROL KITCHEN VENTILATION  

E-print Network

HVAC EFFICIENCY BUSINESS CASE DEMAND CONTROL KITCHEN VENTILATION Selecting, financing ventilation (DCKV) for kitchen exhaust hoods. Implementation can be relatively simple in either new of demand control kitchen ventilation (DCKV) in many small, medium, and large kitchen exhaust hood

California at Davis, University of

318

21 CFR 868.5955 - Intermittent mandatory ventilation attachment.  

Code of Federal Regulations, 2010 CFR

... (a) Identification. An intermittent mandatory ventilation (IMV) attachment is a device attached to a mechanical ventilator that allows spontaneous breathing by a patient while providing mechanical ventilation at a preset rate. (b)...

2010-04-01

319

49 CFR 192.173 - Compressor stations: Ventilation.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Compressor stations: Ventilation. 192.173 Section...Design of Pipeline Components § 192.173 Compressor stations: Ventilation. Each compressor station building must be ventilated to...

2010-10-01

320

46 CFR 108.181 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2010 CFR

...SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Ventilation...means to close each vent or ventilating system. (c) Each fan in a ventilating system must have remote controls...

2010-10-01

321

46 CFR 108.181 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2012 CFR

...SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Ventilation...means to close each vent or ventilating system. (c) Each fan in a ventilating system must have remote controls...

2012-10-01

322

46 CFR 108.181 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Ventilation...means to close each vent or ventilating system. (c) Each fan in a ventilating system must have remote controls...

2011-10-01

323

46 CFR 127.260 - Ventilation for accommodations.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ventilation for accommodations. 127.260 ...Construction and Arrangements § 127.260 Ventilation for accommodations. (a) Each...tons must be provided with a mechanical ventilation system unless the cognizant OCMI...

2011-10-01

324

24 CFR 3280.103 - Light and ventilation.  

... 2014-04-01 false Light and ventilation. 3280.103 Section 3280.103...Considerations § 3280.103 Light and ventilation. (a) Lighting. Each habitable...whichever is greater. (b) Whole-house ventilation. Each manufactured home must be...

2014-04-01

325

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2012-04-01

326

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2013-04-01

327

46 CFR 127.260 - Ventilation for accommodations.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ventilation for accommodations. 127.260 ...Construction and Arrangements § 127.260 Ventilation for accommodations. (a) Each...tons must be provided with a mechanical ventilation system unless the cognizant OCMI...

2013-10-01

328

14 CFR 27.1187 - Ventilation and drainage.  

...2014-01-01 2014-01-01 false Ventilation and drainage. 27.1187 Section...Powerplant Fire Protection § 27.1187 Ventilation and drainage. Each compartment...installation must have provision for ventilation and drainage of flammable fluids....

2014-01-01

329

46 CFR 153.316 - Special cargo pumproom ventilation rate.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Special cargo pumproom ventilation rate. 153.316 Section 153.316...Design and Equipment Cargo Handling Space Ventilation § 153.316 Special cargo pumproom ventilation rate. When Table 1 refers to...

2013-10-01

330

46 CFR 127.260 - Ventilation for accommodations.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Ventilation for accommodations. 127.260 ...Construction and Arrangements § 127.260 Ventilation for accommodations. (a) Each...tons must be provided with a mechanical ventilation system unless the cognizant OCMI...

2012-10-01

331

46 CFR 111.103-3 - Machinery space ventilation.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop...

2011-10-01

332

46 CFR 154.1200 - Mechanical ventilation system: General.  

...2014-10-01 2014-10-01 false Mechanical ventilation system: General. 154.1200 Section...and Equipment Cargo Area: Mechanical Ventilation System § 154.1200 Mechanical ventilation system: General. (a) Each...

2014-10-01

333

49 CFR 192.187 - Vaults: Sealing, venting, and ventilation.  

Code of Federal Regulations, 2013 CFR

...false Vaults: Sealing, venting, and ventilation. 192.187 Section 192.187 ...187 Vaults: Sealing, venting, and ventilation. Each underground vault or closed...millimeters) in diameter; (2) The ventilation must be enough to minimize the...

2013-10-01

334

46 CFR 111.103-3 - Machinery space ventilation.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop...

2013-10-01

335

46 CFR 153.316 - Special cargo pumproom ventilation rate.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Special cargo pumproom ventilation rate. 153.316 Section 153.316...Design and Equipment Cargo Handling Space Ventilation § 153.316 Special cargo pumproom ventilation rate. When Table 1 refers to...

2011-10-01

336

46 CFR 153.316 - Special cargo pumproom ventilation rate.  

...2014-10-01 false Special cargo pumproom ventilation rate. 153.316 Section 153.316...Design and Equipment Cargo Handling Space Ventilation § 153.316 Special cargo pumproom ventilation rate. When Table 1 refers to...

2014-10-01

337

46 CFR 153.316 - Special cargo pumproom ventilation rate.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Special cargo pumproom ventilation rate. 153.316 Section 153.316...Design and Equipment Cargo Handling Space Ventilation § 153.316 Special cargo pumproom ventilation rate. When Table 1 refers to...

2010-10-01

338

24 CFR 3280.103 - Light and ventilation.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 false Light and ventilation. 3280.103 Section 3280.103...Considerations § 3280.103 Light and ventilation. (a) Lighting. Each habitable...whichever is greater. (b) Whole-house ventilation. Each manufactured home must be...

2011-04-01

339

24 CFR 3280.103 - Light and ventilation.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Light and ventilation. 3280.103 Section 3280.103...Considerations § 3280.103 Light and ventilation. (a) Lighting. Each habitable...whichever is greater. (b) Whole-house ventilation. Each manufactured home must be...

2012-04-01

340

24 CFR 3280.103 - Light and ventilation.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Light and ventilation. 3280.103 Section 3280.103...Considerations § 3280.103 Light and ventilation. (a) Lighting. Each habitable...whichever is greater. (b) Whole-house ventilation. Each manufactured home must be...

2013-04-01

341

14 CFR 27.1187 - Ventilation and drainage.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Ventilation and drainage. 27.1187 Section...Powerplant Fire Protection § 27.1187 Ventilation and drainage. Each compartment...installation must have provision for ventilation and drainage of flammable fluids....

2013-01-01

342

21 CFR 888.4230 - Cement ventilation tube.  

...2014-04-01 2014-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2014-04-01

343

49 CFR 192.187 - Vaults: Sealing, venting, and ventilation.  

Code of Federal Regulations, 2011 CFR

...false Vaults: Sealing, venting, and ventilation. 192.187 Section 192.187 ...187 Vaults: Sealing, venting, and ventilation. Each underground vault or closed...millimeters) in diameter; (2) The ventilation must be enough to minimize the...

2011-10-01

344

46 CFR 153.316 - Special cargo pumproom ventilation rate.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Special cargo pumproom ventilation rate. 153.316 Section 153.316...Design and Equipment Cargo Handling Space Ventilation § 153.316 Special cargo pumproom ventilation rate. When Table 1 refers to...

2012-10-01

345

46 CFR 127.260 - Ventilation for accommodations.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ventilation for accommodations. 127.260 ...Construction and Arrangements § 127.260 Ventilation for accommodations. (a) Each...tons must be provided with a mechanical ventilation system unless the cognizant OCMI...

2010-10-01

346

46 CFR 58.01-45 - Machinery space, ventilation.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Machinery space, ventilation. 58.01-45 Section 58.01-45 Shipping COAST...General Requirements § 58.01-45 Machinery space, ventilation. Each machinery space must be ventilated to...

2011-10-01

347

46 CFR 185.352 - Ventilation of gasoline machinery spaces.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Ventilation of gasoline machinery spaces...Operating Requirements § 185.352 Ventilation of gasoline machinery spaces. The mechanical exhaust for the ventilation of a gasoline machinery space,...

2011-10-01

348

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2010-04-01

349

49 CFR 192.187 - Vaults: Sealing, venting, and ventilation.  

Code of Federal Regulations, 2012 CFR

...false Vaults: Sealing, venting, and ventilation. 192.187 Section 192.187 ...187 Vaults: Sealing, venting, and ventilation. Each underground vault or closed...millimeters) in diameter; (2) The ventilation must be enough to minimize the...

2012-10-01

350

46 CFR 154.1200 - Mechanical ventilation system: General.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Mechanical ventilation system: General. 154.1200 Section...and Equipment Cargo Area: Mechanical Ventilation System § 154.1200 Mechanical ventilation system: General. (a) Each...

2012-10-01

351

46 CFR 111.103-3 - Machinery space ventilation.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop...

2012-10-01

352

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2011-04-01

353

46 CFR 154.1200 - Mechanical ventilation system: General.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Mechanical ventilation system: General. 154.1200 Section...and Equipment Cargo Area: Mechanical Ventilation System § 154.1200 Mechanical ventilation system: General. (a) Each...

2013-10-01

354

46 CFR 185.352 - Ventilation of gasoline machinery spaces.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ventilation of gasoline machinery spaces...Operating Requirements § 185.352 Ventilation of gasoline machinery spaces. The mechanical exhaust for the ventilation of a gasoline machinery space,...

2010-10-01

355

14 CFR 27.1187 - Ventilation and drainage.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Ventilation and drainage. 27.1187 Section...Powerplant Fire Protection § 27.1187 Ventilation and drainage. Each compartment...installation must have provision for ventilation and drainage of flammable fluids....

2010-01-01

356

46 CFR 185.352 - Ventilation of gasoline machinery spaces.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Ventilation of gasoline machinery spaces...Operating Requirements § 185.352 Ventilation of gasoline machinery spaces. The mechanical exhaust for the ventilation of a gasoline machinery space,...

2012-10-01

357

46 CFR 185.352 - Ventilation of gasoline machinery spaces.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Ventilation of gasoline machinery spaces...Operating Requirements § 185.352 Ventilation of gasoline machinery spaces. The mechanical exhaust for the ventilation of a gasoline machinery space,...

2013-10-01

358

Quantitative assessment of acute kidney injury by noninvasive arterial spin labeling perfusion MRI: a pilot study.  

PubMed

The kidneys are essential for maintaining homeostasis, are responsible for the reabsorption of water, glucose and amino acids, and filter the blood by removing waste. Acute kidney injury (AKI) is a syndrome characterized by the rapid loss of renal excretory function and the accumulation of end metabolic products of urea and creatinine. AKI is associated with the later development of chronic kidney disease and end-stage kidney disease, and may eventually be fatal. Early diagnosis of AKI and assessments of the effects of treatment, however, are challenging. The pathophysiological mechanism of AKI is thought to be the imbalance between oxygen supply and demand in the kidneys. We have assessed the ability of arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI), without the administration of contrast media, to quantify renal blood flow (RBF) non-invasively. We found that RBF was significantly lower in AKI patients than in healthy volunteers. These results suggest that ASL perfusion MRI, a noninvasive measurement of RBF, may be useful in the early diagnosis of AKI. PMID:23740361

Dong, Jian; Yang, Li; Su, Tao; Yang, XueDong; Chen, Bin; Zhang, Jue; Wang, XiaoYing; Jiang, XueXiang

2013-08-01

359

Commissioning Ventilated Containment Systems in the Laboratory  

SciTech Connect

This Best Practices Guide focuses on the specialized approaches required for ventilated containment systems, understood to be all components that drive and control ventilated enclosures and local exhaust systems within the laboratory. Geared toward architects, engineers, and facility managers, this guide provides information about technologies and practices to use in designing, constructing, and operating operating safe, sustainable, high-performance laboratories.

Not Available

2008-08-01

360

Characterization and measurement of ventilator performance  

NASA Astrophysics Data System (ADS)

The work of the ISO in drawing up ventilator norms is reviewed, and the scientific and technical difficulties encountered when investigating ventilators are summarized. Difficulties arise from the many forms of energy transfered to the fluid, the diversity of gases used, compressibility effects, the wide variety of equipment size and performance, the different functions required, and the heterogeneity of test methods.

Judetlelacombe, A.

361

Infiltration in ASHRAE's Residential Ventilation Standards  

SciTech Connect

The purpose of ventilation is to dilute or remove indoor contaminants that an occupant could be exposed to. It can be provided by mechanical or natural means. ASHRAE Standards including standards 62, 119, and 136 have all considered the contribution of infiltration in various ways, using methods and data from 20 years ago. The vast majority of homes in the United States and indeed the world are ventilated through natural means such as infiltration caused by air leakage. Newer homes in the western world are tight and require mechanical ventilation. As we seek to provide acceptable indoor air quality at minimum energy cost, it is important to neither over-ventilate norunder-ventilate. Thus, it becomes critically important to correctly evaluate the contribution infiltration makes to both energy consumption and equivalent ventilation. ASHRAE Standard 62.2 specifies how much mechanical ventilation is considered necessary to provide acceptable indoor air quality, but that standard is weak on how infiltration can contribute towards meeting the total requirement. In the past ASHRAE Standard 136 was used to do this, but new theoretical approaches and expanded weather data have made that standard out of date. This article will describe how to properly treat infiltration as an equivalent ventilation approach and then use new data and these new approaches to demonstrate how these calculations might be done both in general and to update Standard 136.

Sherman, Max

2008-10-01

362

Clinical review: Long-term noninvasive ventilation  

Microsoft Academic Search

Noninvasive positive ventilation has undergone a remarkable evolution over the past decades and is assuming an important role in the management of both acute and chronic respiratory failure. Long-term ventilatory support should be considered a standard of care to treat selected patients following an intensive care unit (ICU) stay. In this setting, appropriate use of noninvasive ventilation can be expected

Dominique Robert; Laurent Argaud

2007-01-01

363

Alternative ventilation strategies in cardiopulmonary resuscitation  

Microsoft Academic Search

The introduction of the 2000 Guidelines for Cardiopulmonary Resuscitation emphasizes a new, evidence-based approach to the science of ventilation during cardiopulmonary resuscitation (CPR). New laboratory and clinical science underemphasizes the role of ventilation immediately after a dysrhythmic cardiac arrest (arrest primarily resulting from a cardiovascular event, such as ventricular defibrillation or asystole). However, the classic airway patency, breathing, and circulation

Andrea Gabrielli; A. Joseph Layon; Volker Wenzel; Volker Dorges; Ahamed H. Idris

2002-01-01

364

Apparatus for ventilating an enclosed area  

Microsoft Academic Search

This patent describes an apparatus for attachment to a vent tube for ventilating an enclosed area comprising; a tube adaptor for mounting the ventilation apparatus on the vent tube; rotatable hub means secured to and coaxial with the tube adaptor; a substantially hemispherical domelike member rotatably secured to the hub means above the tube adaptor; internal exhaust fan blade means

Schad

1987-01-01

365

Preoperational test report, primary ventilation system  

SciTech Connect

This represents a preoperational test report for Primary Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space filtered venting of tanks AY101, AY102, AZ101, AZ102. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-11-04

366

Body mass index contributes to sympathovagal imbalance in prehypertensives  

PubMed Central

Background The present study was conducted to assess the nature of sympathovagal imbalance (SVI) in prehypertensives by short-term analysis of heart rate variability (HRV) to understand the alteration in autonomic modulation and the contribution of BMI to SVI in the genesis of prehypertension. Methods Body mass index (BMI), basal heart rate (BHR), blood pressure (BP), rate pressure product (RPP) and HRV indices such as total power (TP), low-frequency power (LF), normalized LF (LFnu), high-frequency power (HF), normalized HF (HFnu), LF-HF ratio, mean heart rate (mean RR), square root of the mean squared differences of successive normal to normal intervals (RMSSD), standard deviation of normal to normal RR interval (SDNN), the number of interval differences of successive NN intervals greater than 50?ms (NN50) and the proportion derived by dividing NN50 by the total number of NN intervals (pNN50) were assessed in three groups of subjects: normotensives having normal BMI (Group 1), prehypertensives having normal BMI (Group 2) and prehypertensives having higher BMI (Group 3). SVI was assessed from LF-HF ratio and correlated with BMI, BHR, BP and RPP in all the groups by Pearson correlation. The contribution of BMI to SVI was assessed by multiple regression analysis. Results LF and LFnu were significantly increased and HF and HFnu were significantly decreased in prehypertensive subjects in comparison to normotensive subjects and the magnitude of these changes was more prominent in subjects with higher BMI compared to that of normal BMI. LF-HF ratio, the sensitive indicator of sympathovagal balance had significant correlation with BMI (P?=?0.000) and diastolic blood pressure (DBP) (P?=?0.002) in prehypertensives. BMI was found to be an independent contributing factor to SVI (P?=?0.001) in prehypertensives. Conclusions It was concluded that autonomic imbalance in prehypertensives manifested in the form of increased sympathetic activity and vagal inhibition. In prehypertensives with higher BMI, vagal withdrawal was predominant than sympathetic overactivity. Magnitude of SVI (alteration in LF-HF ratio) was linked to changes in BMI and DBP. BMI had an independent influence on LF-HF ratio. It was advised that life-style modifications such as yoga and exercise would enable achieve the sympathovagal balance and blood pressure homeostasis in prehypertensives. PMID:22812583

2012-01-01

367

The Relation Between Perfusion Pattern of Hepatic Artery Perfusion Scintigraphy and Response to Y-90 Microsphere Therapy  

PubMed Central

Objective: Hepatic artery perfusion scintigraphy is a routine procedure for patient evaluation before Y-90 radiomicrosphere therapy and mostly used for prediction of extrahepatic leakage. Moreover, it also displays perfusion pattern of tumours, which is an important parameter on success of the therapy. The aim of this study is to assess the relation between the perfusion pattern on hepatic artery perfusion scintigraphy and radiomicrosphere therapy response. Methods: A total of 99 radiomicrosphere therapy applications were carried out in 80 patients (M/F: 55/25). Results: Heterogeneous and diffuse perfusion patterns were observed in 47 patients and 52 patients, respectively. The patients with diffuse perfusion pattern had better therapy response both on FDG PET/CT (p= 0.04) and CT (p=0.008) when compared to those with heterogenous perfusion pattern. Conclusion: Perfusion pattern observed on hepatic artery perfusion scintigraphy may be a successful predictor of early response to radiomicrosphere therapy. Conflict of interest:None declared. PMID:24416626

Volkan-Salanc?, Bilge; Bozkurt, Murat Fani; Peynircio?lu, Bora; Çil, Barbaros; U?ur, Ömer

2013-01-01

368

Biomedical Implications of Heavy Metals Induced Imbalances in Redox Systems  

PubMed Central

Several workers have extensively worked out the metal induced toxicity and have reported the toxic and carcinogenic effects of metals in human and animals. It is well known that these metals play a crucial role in facilitating normal biological functions of cells as well. One of the major mechanisms associated with heavy metal toxicity has been attributed to generation of reactive oxygen and nitrogen species, which develops imbalance between the prooxidant elements and the antioxidants (reducing elements) in the body. In this process, a shift to the former is termed as oxidative stress. The oxidative stress mediated toxicity of heavy metals involves damage primarily to liver (hepatotoxicity), central nervous system (neurotoxicity), DNA (genotoxicity), and kidney (nephrotoxicity) in animals and humans. Heavy metals are reported to impact signaling cascade and associated factors leading to apoptosis. The present review illustrates an account of the current knowledge about the effects of heavy metals (mainly arsenic, lead, mercury, and cadmium) induced oxidative stress as well as the possible remedies of metal(s) toxicity through natural/synthetic antioxidants, which may render their effects by reducing the concentration of toxic metal(s). This paper primarily concerns the clinicopathological and biomedical implications of heavy metals induced oxidative stress and their toxicity management in mammals. PMID:25184144

Singh, Shweta; Siddiqi, Nikhat J.

2014-01-01

369

Does Observation of Postural Imbalance Induce a Postural Reaction?  

PubMed Central

Background Several studies bring evidence that action observation elicits contagious responses during social interactions. However automatic imitative tendencies are generally inhibited and it remains unclear in which conditions mere action observation triggers motor behaviours. In this study, we addressed the question of contagious postural responses when observing human imbalance. Methodology/Principal Findings We recorded participants' body sway while they observed a fixation cross (control condition), an upright point-light display of a gymnast balancing on a rope, and the same point-light display presented upside down. Our results showed that, when the upright stimulus was displayed prior to the inverted one, centre of pressure area and antero-posterior path length were significantly greater in the upright condition compared to the control and upside down conditions. Conclusions/Significance These results demonstrate a contagious postural reaction suggesting a partial inefficiency of inhibitory processes. Further, kinematic information was sufficient to trigger this reaction. The difference recorded between the upright and upside down conditions indicates that the contagion effect was dependent on the integration of gravity constraints by body kinematics. Interestingly, the postural response was sensitive to habituation, and seemed to disappear when the observer was previously shown an inverted display. The motor contagion recorded here is consistent with previous work showing vegetative output during observation of an effortful movement and could indicate that lower level control facilitates contagion effects. PMID:21423622

Tia, Banty; Saimpont, Arnaud; Paizis, Christos; Mourey, France; Fadiga, Luciano; Pozzo, Thierry

2011-01-01

370

Allelic Imbalance in Drosophila Hybrid Heads: Exons, Isoforms, and Evolution  

PubMed Central

Unraveling how regulatory divergence contributes to species differences and adaptation requires identifying functional variants from among millions of genetic differences. Analysis of allelic imbalance (AI) reveals functional genetic differences in cis regulation and has demonstrated differences in cis regulation within and between species. Regulatory mechanisms are often highly conserved, yet differences between species in gene expression are extensive. What evolutionary forces explain widespread divergence in cis regulation? AI was assessed in Drosophila melanogaster–Drosophila simulans hybrid female heads using RNA-seq technology. Mapping bias was virtually eliminated by using genotype-specific references. Allele representation in DNA sequencing was used as a prior in a novel Bayesian model for the estimation of AI in RNA. Cis regulatory divergence was common in the organs and tissues of the head with 41% of genes analyzed showing significant AI. Using existing population genomic data, the relationship between AI and patterns of sequence evolution was examined. Evidence of positive selection was found in 30% of cis regulatory divergent genes. Genes involved in defense, RNAi/RISC complex genes, and those that are sex regulated are enriched among adaptively evolving cis regulatory divergent genes. For genes in these groups, adaptive evolution may play a role in regulatory divergence between species. However, there is no evidence that adaptive evolution drives most of the cis regulatory divergence that is observed. The majority of genes showed patterns consistent with stabilizing selection and neutral evolutionary processes. PMID:22319150

Graze, R. M.; Novelo, L. L.; Amin, V.; Fear, J. M.; Casella, G.; Nuzhdin, S. V.; McIntyre, L. M.

2012-01-01

371

22 year cycle in the imbalance of the photospheric magnetic fluxes  

NASA Astrophysics Data System (ADS)

The manifestation of the 22 year solar magnetic cycle in the imbalance of positive and negative photospheric magnetic fluxes is studied. For the analysis we use synoptic maps of the photospheric magnetic field of Kitt Peak Observatory (1976 - 2003) and John Wilcox Observatory in Stanford (1976 - 2012). We consider strong magnetic fields for the heliolatitudes in the interval from +40° to -40°. It is shown that the sign of the imbalance between positive and negative fluxes remains constant during 11 years from one inversion of the Sun’s global magnetic field to the next one and always coincides with the sign of the polar field in the Northern hemisphere. Thus, the imbalance between the magnetic fluxes of different polarities changes according to the 22 year cycle. The sign of the imbalance is determined both by the phase of the solar cycle (before or after the inversion) and by the parity of the solar cycle. The imbalance of positive and negative magnetic fluxes can be observed not only for the strong fields in the sunspot zone. The mean magnetic field of the Sun (Sun as a star), which is determined by the net flux of the background fields, changes according to the same pattern as the imbalance of the strong fields. The regular changes of the imbalance of the photospheric magnetic fields are reflected also in the parameters of heliosphere. We show the connection of the imbalance with the quadrupole component of the photospheric magnetic field and with the imbalance of the interplanetary magnetic field (the difference between the numbers of the days with positive and negative polarities of the interplanetary magnetic field near Earth).

Vernova, Elena; Baranov, Dmitrii; Tyasto, Marta

372

Cardiac tissue engineering using perfusion bioreactor systems  

PubMed Central

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

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

2009-01-01

373

Determination of an adequate perfusion pressure for continuous dual vessel hypothermic machine perfusion of the rat liver.  

PubMed

Hypothermic machine perfusion (HMP) provides better protection against ischemic damage of the kidney compared to cold-storage. The required perfusion pressures needed for optimal HMP of the liver are, however, unknown. Rat livers were preserved in University of Wisconsin organ preservation solution enriched with acridine orange (AO) to stain viable cells and propidium iodide (PI) to detect dead cells. Perfusion pressures of 12.5%, 25% or 50% of physiologic perfusion pressures were compared. Intravital fluorescence microscopy was used to assess liver perfusion by measuring the percentage of AO staining. After 1-h, the perfusion pressure of 12.5% revealed 72% +/- 3% perfusion of mainly the acinary zones one and two. The perfusion pressure of 25% and 50% showed complete perfusion. Furthermore, 12.5% showed 14.7 +/- 3.6, 25% showed 3.7 +/- 0.9, and 50% showed 11.2 +/- 1.4 PI positive cells. One hour was followed by another series of experiments comprising 24-h preservation. In comparison with 24-h cold-storage, HMP at 25% showed less PI positive cells and HMP at 50% showed more PI positive cells. In summary, perfusion at 25% showed complete perfusion, demonstrated by AO staining, with minimal cellular injury, shown with PI. This study indicates that fine-tuning of the perfusion pressure is crucial to balance (in)complete perfusion and endothelial injury. PMID:17326775

't Hart, Nils A; der van Plaats, Arjan; Leuvenink, Henri G D; van Goor, Harry; Wiersema-Buist, Janneke; Verkerke, Gijsbertus J; Rakhorst, Gerhard; Ploeg, Rutger J

2007-04-01

374

Optical Perfusion and Oxygenation Characterization in a Liver Phantom  

E-print Network

Continuous monitoring of blood perfusion and oxygenation is essential in assessing the health of a transplanted organ. Particularly, monitoring the perfusion and oxygenation of the organ during the two-week period after the transplant procedure...

King, Travis J.

2012-02-14

375

Blood leakage and melphalan leakage from the perfusion circuit during regional hyperthermic perfusion for malignant melanoma  

SciTech Connect

In regional hyperthermic perfusion with melphalan for patients with malignant melanoma of the leg, plasma leakage between the perfusion circuit and the systemic circulation was 4-7 ml X min-1. The melphalan concentration in the perfusate was biphasic, with half-lives of 8-12 mins for the initial phase and 19-28 mins for the second phase, after the first dose. After a second dose, the corresponding values were 11-13 and 26-34 mins. The highest concentration in general circulation was 0.38 micrograms X ml-1.

Hafstroem, L.; Hugander, A.; Joensson, P.E.; Westling, H.; Ehrsson, H.

1984-06-01

376

Dynamic perfusion patterns in temporal lobe epilepsy  

Microsoft Academic Search

Purpose  To investigate dynamic ictal perfusion changes during temporal lobe epilepsy (TLE).\\u000a \\u000a \\u000a \\u000a Methods  We investigated 37 patients with TLE by ictal and interictal SPECT. All ictal injections were performed within 60 s of seizure\\u000a onset. Statistical parametric mapping was used to analyse brain perfusion changes and temporal relationships with injection\\u000a time and seizure duration as covariates.\\u000a \\u000a \\u000a \\u000a Results  The analysis revealed significant ictal hyperperfusion in

Patrick Dupont; John J. Zaknun; Alex Maes; Supatporn Tepmongkol; Silvia Vasquez; C. S. Bal; Wim Van Paesschen; Silvina Carpintiero; Chaichon Locharernkul; Maurizio Dondi

2009-01-01

377

Position paper - primary ventilation system configuration  

SciTech Connect

The purpose of this paper is to develop and document a position on the configuration of the primary ventilation system. This configuration will be used on the waste storage tanks currently being designed for the Multi-Function Waste Tank Facility. The primary ventilation system provides a single treatment train and exhaust fan for each waste storage tank. The ventilation systems from each of two tanks are grouped with an additional treatment train and exhaust fan that function as backup to either of the two systems.

Dalpiaz, E.L.

1994-06-01

378

Preoperational test report, primary ventilation condensate system  

SciTech Connect

Preoperational test report for Primary Ventilation Condensate System, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides a collection point for condensate generated by the W-030 primary vent offgas cooling system serving tanks AYIOI, AY102, AZIOI, AZI02. The system is located inside a shielded ventilation equipment cell and consists of a condensate seal pot, sampling features, a drain line to existing Catch Tank 241-AZ-151, and a cell sump jet pump. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-01-29

379

Effects of laser acupuncture on blood perfusion rate  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

380

Association of sympathovagal imbalance with cardiovascular risks in young prehypertensives.  

PubMed

Although cardiovascular (CV) risks have been reported in prehypertension, their link to sympathovagal imbalance (SVI) has not been investigated. In the present study, we have assessed the factors contributing to SVI and the prediction of CV risk by SVI in prehypertensives. Body mass index, CV parameters such as heart rate, systolic blood pressure (BP), diastolic BP, mean arterial pressure, rate-pressure product (RPP), stroke volume, left ventricular ejection time, cardiac output, total peripheral resistance, baroreflex sensitivity recorded by continuous blood pressure variability monitoring using Finapres, autonomic function tests recorded by spectral analysis of heart rate variability (HRV), and heart rate and BP responses to standing, deep breathing, and isometric handgrip, and biochemical parameters such as homeostatic model assessment of insulin resistance, lipid risk factors, inflammatory markers, thyroid profile, and renin and oxidative stress parameters were analyzed in young normotensives (n = 118) and prehypertensives (n = 58). Contribution of CV risks to low-frequency/high-frequency (LF/HF) ratio of HRV, the marker of SVI, was determined by multiple regression analysis, and prediction of SVI to RPP, a known CV risk, was assessed by logisitic regression adjusted for body mass index. BP variability, HRV, and autonomic function test parameters were significantly altered in prehypertensives and these parameters were correlated with LF/HF. Insulin resistance, dyslipidemia, inflammation, and oxidative stress contributed to SVI in prehypertensives. LF/HF and baroreflex sensitivity had significant prediction of RPP in prehypertensives. In conclusion, SVI in young prehypertensives is due to both increased sympathetic and decreased vagal tone. CV risks are linked to SVI and SVI predicts cardiac risk in prehypertensives. PMID:24035167

Pal, Gopal K; Adithan, Chandrasekaran; Ananthanarayanan, Palghat H; Pal, Pravati; Nanda, Nivedita; Thiyagarajan, Durgadevi; Syamsunderkiran, Avupati N; Lalitha, Venugopal; Dutta, Tarun K

2013-12-01

381

T lymphocyte subset imbalances in patients contribute to ankylosing spondylitis  

PubMed Central

Ankylosing spondylitis is a chronic inflammatory rheumatic disease, which is characterized by inflammation of the spine and the sacroiliac joints. To date, the disease etiology remains unclear. In the present study, the correlation of T lymphocyte subset changes with the progression of ankylosing spondylitis was investigated. A total of 55 patients with ankylosing spondylitis (22 severe and 23 mild cases) and 20 healthy individuals were selected. Firstly, the punctured cells in the lesions and the serum were collected, and the lymphocytes and the peripheral blood mononuclear cells were prepared. Secondly, quantitative PCR, ELISA and flow cytometry analyses were carried out to detect the levels of a series of immunoglobulins, complements, helper T cells, cytotoxic T cells, regulatory cells and cytokines. The expression levels of ?-globulin, ?-globulin, immunoglobulin (Ig)G, IgA, IgM, serum complement C3, and complement C4 were found to be significantly increased in ankylosing spondylitis patients. In addition, the percentage of Th1 and Th17 cells was found to be significantly higher in the ankylosing spondylitis groups (mild and severe) compared with the healthy individuals. As a result, the Th1/Th2 and Th17/Treg ratios were significantly higher in patients with ankylosing spondylitis. In addition, T lymphocyte subset ratio imbalances contributed to an increased expression of immune mediators, including interferon (IFN)-? and interleukin (IL)-17A. The mRNA and protein expression levels of IFN-? and IL-17A were found to be higher in the ankylosing spondylitis groups compared with the control group. The present study provided further evidence on the function and underlying mechanism of T lymphocyte subsets, which may be useful in the diagnosis and treatment of ankylosing spondylitis. PMID:25452811

WANG, CHENGGONG; LIAO, QIANDE; HU, YIHE; ZHONG, DA

2015-01-01

382

T lymphocyte subset imbalances in patients contribute to ankylosing spondylitis.  

PubMed

Ankylosing spondylitis is a chronic inflammatory rheumatic disease, which is characterized by inflammation of the spine and the sacroiliac joints. To date, the disease etiology remains unclear. In the present study, the correlation of T lymphocyte subset changes with the progression of ankylosing spondylitis was investigated. A total of 55 patients with ankylosing spondylitis (22 severe and 23 mild cases) and 20 healthy individuals were selected. Firstly, the punctured cells in the lesions and the serum were collected, and the lymphocytes and the peripheral blood mononuclear cells were prepared. Secondly, quantitative PCR, ELISA and flow cytometry analyses were carried out to detect the levels of a series of immunoglobulins, complements, helper T cells, cytotoxic T cells, regulatory cells and cytokines. The expression levels of ?-globulin, ?-globulin, immunoglobulin (Ig)G, IgA, IgM, serum complement C3, and complement C4 were found to be significantly increased in ankylosing spondylitis patients. In addition, the percentage of Th1 and Th17 cells was found to be significantly higher in the ankylosing spondylitis groups (mild and severe) compared with the healthy individuals. As a result, the Th1/Th2 and Th17/Treg ratios were significantly higher in patients with ankylosing spondylitis. In addition, T lymphocyte subset ratio imbalances contributed to an increased expression of immune mediators, including interferon (IFN)-? and interleukin (IL)-17A. The mRNA and protein expression levels of IFN-? and IL-17A were found to be higher in the ankylosing spondylitis groups compared with the control group. The present study provided further evidence on the function and underlying mechanism of T lymphocyte subsets, which may be useful in the diagnosis and treatment of ankylosing spondylitis. PMID:25452811

Wang, Chenggong; Liao, Qiande; Hu, Yihe; Zhong, DA

2015-01-01

383

Assessment of Infantile Mineral Imbalances in Autism Spectrum Disorders (ASDs)  

PubMed Central

The interactions between genes and the environment are now regarded as the most probable explanation for autism. In this review, we summarize the results of a metallomics study in which scalp hair concentrations of 26 trace elements were examined for 1,967 autistic children (1,553 males and 414 females aged 0–15 years-old), and discuss recent advances in our understanding of epigenetic roles of infantile mineral imbalances in the pathogenesis of autism. In the 1,967 subjects, 584 (29.7%) and 347 (17.6%) were found deficient in zinc and magnesium, respectively, and the incidence rate of zinc deficiency was estimated at 43.5% in male and 52.5% in female infantile subjects aged 0–3 years-old. In contrast, 339 (17.2%), 168 (8.5%) and 94 (4.8%) individuals were found to suffer from high burdens of aluminum, cadmium and lead, respectively, and 2.8% or less from mercury and arsenic. High toxic metal burdens were more frequently observed in the infants aged 0–3 years-old, whose incidence rates were 20.6%, 12.1%, 7.5%, 3.2% and 2.3% for aluminum, cadmium, lead, arsenic and mercury, respectively. These findings suggest that infantile zinc- and magnesium-deficiency and/or toxic metal burdens may be critical and induce epigenetic alterations in the genes and genetic regulation mechanisms of neurodevelopment in the autistic children, and demonstrate that a time factor “infantile window” is also critical for neurodevelopment and probably for therapy. Thus, early metallomics analysis may lead to early screening/estimation and treatment/prevention for the autistic neurodevelopment disorders. PMID:24284360

Yasuda, Hiroshi; Tsutsui, Toyoharu

2013-01-01

384

Imbalance of ionic conductances contributes to diverse symptoms of demyelination  

PubMed Central

Fast axonal conduction of action potentials in mammals relies on myelin insulation. Demyelination can cause slowed, blocked, desynchronized, or paradoxically excessive spiking that underlies the symptoms observed in demyelination diseases. The diversity and timing of such symptoms are poorly understood, often intermittent, and uncorrelated with disease progress. We modeled the effects of demyelination (and secondary remodeling) on intrinsic axonal excitability using Hodgkin–Huxley and reduced Morris–Lecar models. Simulations and analysis suggested a simple explanation for the breadth of symptoms and revealed that the ratio of sodium to leak conductance, gNa/gL, acted as a four-way switch controlling excitability patterns that included spike failure, single spike transmission, afterdischarge, and spontaneous spiking. Failure occurred when this ratio fell below a threshold value. Afterdischarge occurred at gNa/gL just below the threshold for spontaneous spiking and required a slow inward current that allowed for two stable attractor states, one corresponding to quiescence and the other to repetitive spiking. A neuron prone to afterdischarge could function normally unless it was switched to its “pathological” attractor state; thus, although the underlying pathology may develop slowly by continuous changes in membrane conductances, a discontinuous change in axonal excitability can occur and lead to paroxysmal symptoms. We conclude that tonic and paroxysmal positive symptoms as well as negative symptoms may be a consequence of varying degrees of imbalance between gNa and gL after demyelination. The KCNK family of gL potassium channels may be an important target for new drugs to treat the symptoms of demyelination. PMID:20974975

Coggan, Jay S.; Prescott, Steven A.; Bartol, Thomas M.; Sejnowski, Terrence J.

2010-01-01

385

KRAS mutant allele-specific imbalance in lung adenocarcinoma.  

PubMed

The significance of KRAS mutant allele-specific imbalance (MASI) in lung adenocarcinomas is unknown. KRAS MASI was defined as predominance of the mutant allele over the wild-type allele. We assessed the frequency of KRAS MASI by comparing peak heights of mutant and wild-type alleles on sequencing electropherograms and by KRAS fluorescence in situ hybridization (FISH). A review of sequencing electropherograms of 207 KRAS-mutated lung adenocarcinomas demonstrated 23 (11%) cases with the mutant allele peak higher than the wild-type allele peak and 15 (7%) cases with the mutant allele peak equal to the wild-type allele peak. Of 17 cases with the mutant allele peak higher or equal to the wild-type allele peak, 8 (47%) showed KRAS amplification by FISH. KRAS FISH analysis of 36 KRAS-mutated lung adenocarcinomas with the mutant allele peak lower than the wild-type allele peak, 21 KRAS and EGFR wild-type and 16 EGFR-mutated adenocarcinomas showed no KRAS amplification. KRAS MASI was associated with selective amplification of the KRAS mutant allele (P<0.001). Patients with KRAS MASI showed worse overall survival. The cumulative proportion surviving at 17 months for KRAS MASI group was 35% compared with 84.1% for patients with KRAS mutant allele peak lower than wild-type allele peak (P=0.012). The adverse prognostic significance of KRAS MASI was independent of clinical stage and was maintained among stage I patients. The detection of KRAS MASI in lung adenocarcinomas by sequencing electropherograms may identify patients with more aggressive disease. PMID:21743433

Chiosea, Simion I; Sherer, Carol K; Jelic, Tomislav; Dacic, Sanja

2011-12-01

386

Measuring Residential Ventilation System Airflows: Part 1 Laboratory  

E-print Network

1 Measuring Residential Ventilation System Airflows: Part 1 ­ Laboratory Evaluation of Airflow: residential, mechanical ventilation, measurement, ASHRAE 62.2, flow hood ABSTRACT Building codes increasingly require tighter homes and mechanical ventilation per ASHRAE Standard 62.2. These ventilation flows must

387

THE MECHANICS OF LUNG TISSUE UNDER HIGH-FREQUENCY VENTILATION  

E-print Network

THE MECHANICS OF LUNG TISSUE UNDER HIGH-FREQUENCY VENTILATION MARKUS R. OWEN AND MARK A. LEWIS Abstract. High frequency ventilation is a radical departure from conventional lung ventilation question concerns ventilator induced damage to the lung tissue, and a clear protocol for the most effective

388

Round table March 2005, Brussels The ventilator of tomorrow  

E-print Network

Round table ­ March 2005, Brussels The ventilator of tomorrow Laurent Brochard, MD, Michel Dojat (France) Tél. 01.49.81.25.45 e-mail : laurent.brochard@hmn.aphp.fr #12;The ventilator of our dreams does this ventilator. Technology is very present in the intensive care unit. The field of mechanical ventilation has

Dojat, Michel

389

THE MECHANICS OF LUNG TISSUE UNDER HIGH-FREQUENCY VENTILATION  

E-print Network

THE MECHANICS OF LUNG TISSUE UNDER HIGH-FREQUENCY VENTILATION MARKUS R. OWEN AND MARK A. LEWIS SIAM­1761 Abstract. High-frequency ventilation is a radical departure from conventional lung ventilation question concerns ventilator-induced damage to the lung tissue, and a clear protocol for the most effective

Lewis, Mark

390

30 CFR 77.1911 - Ventilation of slopes and shafts.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Ventilation of slopes and shafts. 77.1911...Slope and Shaft Sinking § 77.1911 Ventilation of slopes and shafts. (a) All...shafts shall be ventilated by mechanical ventilation equipment during development....

2011-07-01

391

30 CFR 77.1911 - Ventilation of slopes and shafts.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Ventilation of slopes and shafts. 77.1911...Slope and Shaft Sinking § 77.1911 Ventilation of slopes and shafts. (a) All...shafts shall be ventilated by mechanical ventilation equipment during development....

2013-07-01

392

30 CFR 77.1911 - Ventilation of slopes and shafts.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Ventilation of slopes and shafts. 77.1911...Slope and Shaft Sinking § 77.1911 Ventilation of slopes and shafts. (a) All...shafts shall be ventilated by mechanical ventilation equipment during development....

2012-07-01

393

The effect of mono(2-ethylhexyl)phthalate on an isolated perfused rat heart-lung preparation.  

PubMed Central

Di(2-ethylhexyl)phthalate (DEHP), the plasticizer used in the biomedical production of blood storage bags, hemodialysis systems, cardiopulmonary bypass (CPB) circuitry, and intubation tubes, is extracted from the plastic material when it comes into contact with biological fluids and is converted to its principal metabolite, mono(2-ethylhexyl)phthalate (MEHP). We have shown that MEHP causes cardiac and respiratory arrest, as well as hypotension, when infused into anesthetized rats. Using a well-ventilated in vitro rat heart-lung preparation, we investigated the effect of MEHP on pulmonary artery pressure (PAP) and found that MEHP had a hypertensive effect on the pulmonary vasculature ending in constriction and edema. There was a significant increase of 0.58 mm Hg/min in the PAP of isolated rat lungs when perfused with MEHP dissolved in Krebs-Henseleit (K-H) buffer (p = 0.0003). The rat lungs that were perfused with K-H buffer only increased 0.094 mm Hg/min during the same perfusion time of 20 min. The water gained during this time was 0.22 g/min with MEHP in the buffer compared to 0.04 g/min with buffer alone. The pO2 in the effluent did not decrease during the perfusion time. The concentration of MEHP in the rat lungs after perfusion varied from 20 to 40 micrograms/g. Although the mechanism of action of MEHP on PAP is too complex to be fully elucidated by this model, the increase in PAP which we have demonstrated is significant and adds yet another toxic effect of this major metabolite of the ubiquitous plasticizer, DEHP. PMID:2088746

Labow, R S; Barry, Y A; Tocchi, M; Keon, W J

1990-01-01

394

C h a p t e r o n e trade Imbalances and the  

E-print Network

--fiscal union or, as I discuss in chapter 6, a major reversal of German trade imbalances--seem politically is likely to be on the political elite, who have benefitted most from the existing growth model

Landweber, Laura

395

SYSTEMIC IMBALANCE OF ESSENTIAL METALS AND CARDIAC GENE EXPRESSION IN RATS FOLLOWING ACUTE PULMONARY ZINC EXPOSURE  

EPA Science Inventory

We have recently demonstrated that PM containing water-soluble zinc may cause cardiac injury following pulmonary exposure. To investigate if pulmonary zinc exposure causes systemic metal imbalance and direct cardiac effects, we intratracheally (IT) instilled male Wistar Kyoto (WK...

396

Continuous covariate imbalance and conditional power for clinical trial interim analyses.  

PubMed

Oftentimes valid statistical analyses for clinical trials involve adjustment for known influential covariates, regardless of imbalance observed in these covariates at baseline across treatment groups. Thus, it must be the case that valid interim analyses also properly adjust for these covariates. There are situations, however, in which covariate adjustment is not possible, not planned, or simply carries less merit as it makes inferences less generalizable and less intuitive. In this case, covariate imbalance between treatment groups can have a substantial effect on both interim and final primary outcome analyses. This paper illustrates the effect of influential continuous baseline covariate imbalance on unadjusted conditional power (CP), and thus, on trial decisions based on futility stopping bounds. The robustness of the relationship is illustrated for normal, skewed, and bimodal continuous baseline covariates that are related to a normally distributed primary outcome. Results suggest that unadjusted CP calculations in the presence of influential covariate imbalance require careful interpretation and evaluation. PMID:24607294

Ciolino, Jody D; Martin, Renee' H; Zhao, Wenle; Jauch, Edward C; Hill, Michael D; Palesch, Yuko Y

2014-05-01

397

On the consequences of the energy imbalance for calculating surface conductance to water vapour  

PubMed Central

The Penman-Monteith combination equation, which is most frequently used to derive the surface conductance to water vapour (Gs), implicitly assumes the energy balance to be closed. Any energy imbalance (positive or negative) will thus affect the calculated Gs. Using eddy covariance energy flux data from a temperate grassland and a desert shrub ecosystem we explored five possible approaches of closing the energy imbalance and show that calculated Gs may differ considerably between these five approaches depending on the relative magnitudes of sensible and latent heat fluxes, and the magnitude and sign of the energy imbalance. Based on our limited understanding of the nature of the energy imbalance, we tend to favour an approach which preserves the Bowen-ratio and closes the energy balance on a larger time scale. PMID:24465070

Wohlfahrt, Georg; Haslwanter, Alois; Hörtnagl, Lukas; Jasoni, Richard L.; Fenstermaker, Lynn F.; Arnone, John A.; Hammerle, Albin

2014-01-01

398

Spin imbalance in hybrid superconducting structures with spin-active interfaces  

NASA Astrophysics Data System (ADS)

We consider a heterostructure consisting of a normal metal and a superconductor separated by a spin-active interface. At finite-bias voltages, spin-filtering and spin-mixing effects at the interface allow for an induced magnetization (spin imbalance) on the superconducting side of the junction, which relaxes to zero in the bulk. Such interfaces are also known to host a pair of in-gap Andreev bound states which were recently observed experimentally. We show that these states are responsible for the dominant contribution to the induced spin imbalance close to the interface. Motivated by recent experiments on spin-charge density separation in superconducting aluminum wires, we propose an alternative way to observe spin imbalance without applying an external magnetic field. We also suggest that the peculiar dependence of the spin imbalance on the applied bias voltage permits an indirect bound-state spectroscopy.

Shevtsov, Oleksii; Löfwander, Tomas

2014-08-01

399

A single-to-differential low-noise amplifier with low differential output imbalance  

NASA Astrophysics Data System (ADS)

This paper presents a single-ended input differential output low-noise amplifier intended for GPS applications. We propose a method to reduce the gain/amplitude and phase imbalance of a differential output exploiting the inductive coupling of a transformer or center-tapped differential inductor. A detailed analysis of the theory of imbalance reduction, as well as a discussion on the principle of choosing the dimensions of a transformer, are given. An LNA has been implemented using TSMC 0.18 ?m technology with ESD-protected. Measurement on board shows a voltage gain of 24.6 dB at 1.575 GHz and a noise figure of 3.2 dB. The gain imbalance is below 0.2 dB and phase imbalance is less than 2 degrees. The LNA consumes 5.2 mA from a 1.8 V supply.

Lian, Duan; Wei, Huang; Chengyan, Ma; Xiaofeng, He; Yuhua, Jin; Tianchun, Ye

2012-03-01

400

Are foreign investments in land leading to an imbalance in the hydrological cycle?  

NASA Astrophysics Data System (ADS)

Over the past few years, large-scale acquisitions of farmland have taken place across the world. Although the land acquisitions are generally portrayed as a land grab in Africa, in almost all cases it is the extra water that is consumed by the crops that brings a new imbalance in the hydrological science. Understanding the imbalance is central to livelihoods and food security of the people downstream because almost all rivers in Africa with the exception of the Congo are being fully consumed before they enter the ocean. In this talk we will show what the effects on the water imbalance caused by foreign and national investments in the Blue Nile basin in the Ethiopian highlands has on the water availability in the downstream countries and whether the imbalance can be made up by increasing irrigation efficiency.

Steenhuis, T. S.; Theodore, C.; Makki, F. M.

2012-12-01

401

Myocardial Perfusion Scintigraphy: Effect on Diagnostic and Clinical Management Algorithms  

Microsoft Academic Search

Research has demonstrated that myocardial perfusion imaging increases the sensitivity and specificity of stress electrocardiogra- phy. However, the additional effect of the perfusion component of a stress study on clinical management algorithms remains poorly defined. Methods: We prospectively assessed the decision-making process in 518 patients, from 191 clinicians, undergoing stress myocardial perfusion imaging in our departments. Each clinician was asked,

Nathan Better; J. Anthony Parker; Thomas P. Rocco; Michael Simons; Ernesto V. Cervino

402

Perfusion MRI: The Five Most Frequently Asked Clinical Questions  

PubMed Central

OBJECTIVE This article addresses questions that radiologists frequently ask when planning, performing, processing, and interpreting MRI perfusion studies in CNS imaging. CONCLUSION Perfusion MRI is a promising tool in assessing stroke, brain tumors, and neurodegenerative diseases. Most of the impediments that have limited the use of perfusion MRI can be overcome to allow integration of these methods into modern neuroimaging protocols. PMID:23971482

Essig, Marco; Nguyen, Thanh Binh; Shiroishi, Mark S.; Saake, Marc; Provenzale, James M.; Enterline, David S.; Anzalone, Nicoletta; Dörfler, Arnd; Rovira, Àlex; Wintermark, Max; Law, Meng

2013-01-01

403

Inhaled antibiotic therapy for ventilator-associated tracheobronchitis and ventilator-associated pneumonia: an Update  

Microsoft Academic Search

Ventilator-associated pneumonia (VAP) remains a leading cause of morbidity and mortality in mechanically-ventilated patients\\u000a in the Intensive Care Unit (ICU). Ventilator-associated tracheobronchitis (VAT) was previously believed to be an intermediate\\u000a stage between colonization of the lower respiratory tract and VAP. More recent data, however, suggest that VAT may be a separate\\u000a entity that increases morbidity and mortality, independently of the

Tareq Abu-Salah; Rajiv Dhand

404

Examination of Potential Benefits of an Energy Imbalance Market in the Western Interconnection  

SciTech Connect

In the Western Interconnection, there is significant interest in improving approaches to wide-area coordinated operations of the bulk electric power system, in part because of the increasing penetration of variable generation. One proposed solution is an energy imbalance market. This study focused on that approach alone, with the goal of identifying the potential benefits of an energy imbalance market in the year 2020.

Milligan, M.; Clark, K.; King, J.; Kirby, B.; Guo, T.; Liu, G.

2013-03-01

405

Joint compensation of IQ imbalance and frequency offset in OFDM systems  

Microsoft Academic Search

Zero-IF receivers are gaining interest because of their potential to enable low-cost OFDM terminals. However, zero-IF receivers introduce IQ imbalance which may have a huge impact on the performance. Rather than increasing design time or component cost to decrease the IQ unbalance, an alternative is to tolerate the IQ imbalance and compensate it digitally. Current solutions require extra analog hardware

J. Tubbax; B. Come; L. Van der Perre; S. Donnay; M. Engels; M. Moonen; H. De Man

2003-01-01

406

Respiratory care year in review 2010: part 2. Invasive mechanical ventilation, noninvasive ventilation, pediatric mechanical ventilation, aerosol therapy.  

PubMed

The purpose of this paper is to review the recent literature related to invasive mechanical ventilation, NIV, pediatric mechanical ventilation, and aerosol therapy. Topics covered related to invasive mechanical ventilation topics include the role of PEEP in providing lung protection during mechanical ventilation, unconventional modes for severe hypoxemia, and strategies to improve patient-ventilator interactions. Topics covered related to NIV include real-life NIV use, NIV and extubation failure, and NIV and pandemics. For pediatric mechanical ventilation, the topics addressed are NIV, invasive respiratory support, and inhaled nitric oxide. Topics covered related to aerosol therapy include short-acting ?-adrenergic agents, long-acting ?-adrenergic agents, long-acting antimuscarinic agents, inhaled corticosteroid therapy, phosphodiesterase type 4 (PDE4) inhibitors, long-acting ?-adrenergic plus inhaled corticosteroid, long-acting antimuscarinic plus inhaled corticosteroid, nebulized hypertonic saline, inhaled mannitol, and inhaled antibiotic therapy. These topics were chosen and reviewed in a manner that is most likely to have interest to the readers of Respiratory Care. PMID:21669105

Macintyre, Neil R; Nava, Stefano; Diblasi, Robert M; Restrepo, Ruben D; Hess, Dean R

2011-05-01

407

MR-compatible ventilator for small animals: computer-controlled ventilation for proton and noble gas imaging  

E-print Network

MR-compatible ventilator for small animals: computer-controlled ventilation for proton and noble; accepted 28 April 2000 Abstract We describe an MR-compatible ventilator that is computer controlled, and to support delivery of gas anesthesia and experimental inhalational gases. A key feature of this ventilator

408

Aspekter som avgör anestesisjuksköterskans val av peroperativ ventilation vid bukkirurgi, volym eller tryckkontrollerad ventilation?.  

E-print Network

?? Bakgrund. Enligt den nya kompetensbeskrivningen för anestesisjuksköterskor framgår bland annat att anestesisjuksköterskan ska ha kompetens att övervaka och följa upp ventilation och cirkulation hos… (more)

Chowdhury, Patrik

2009-01-01

409

Line-of-sight magnetic flux imbalances caused by electric currents  

NASA Technical Reports Server (NTRS)

Several physical and observational effects contribute to the significant imbalances of magnetic flux that are often observed in active regions. We consider an effect not previously treated: the influence of electric currents in the photosphere. Electric currents can cause a line-of-sight flux imbalance because of the directionality of the magnetic field they produce. Currents associated with magnetic flux tubes produce larger imbalances than do smoothly-varying distributions of flux and current. We estimate the magnitude of this effect for current densities, total currents, and magnetic geometry consistent with observations. The expected imbalances lie approximately in the range 0-15%, depending on the character of the current-carying fields and the angle from which they are viewed. Observationally, current-induced flux imbalances could be indicated by a statistical dependence of the imbalance on angular distance from disk center. A general study of magnetic flux balance in active regions is needed to determine the relative importance of other- probably larger- effects such as dilute flux (too weak to measure or rendered invisible by radiative transfer effects), merging with weak background fields, and long-range connections between active regions.

Gary, G. Allen; Rabin, Douglas

1995-01-01

410

Wide brick tunnel randomization - an unequal allocation procedure that limits the imbalance in treatment totals.  

PubMed

In open-label studies, partial predictability of permuted block randomization provides potential for selection bias. To lessen the selection bias in two-arm studies with equal allocation, a number of allocation procedures that limit the imbalance in treatment totals at a pre-specified level but do not require the exact balance at the ends of the blocks were developed. In studies with unequal allocation, however, the task of designing a randomization procedure that sets a pre-specified limit on imbalance in group totals is not resolved. Existing allocation procedures either do not preserve the allocation ratio at every allocation or do not include all allocation sequences that comply with the pre-specified imbalance threshold. Kuznetsova and Tymofyeyev described the brick tunnel randomization for studies with unequal allocation that preserves the allocation ratio at every step and, in the two-arm case, includes all sequences that satisfy the smallest possible imbalance threshold. This article introduces wide brick tunnel randomization for studies with unequal allocation that allows all allocation sequences with imbalance not exceeding any pre-specified threshold while preserving the allocation ratio at every step. In open-label studies, allowing a larger imbalance in treatment totals lowers selection bias because of the predictability of treatment assignments. The applications of the technique in two-arm and multi-arm open-label studies with unequal allocation are described. PMID:24302448

Kuznetsova, Olga M; Tymofyeyev, Yevgen

2014-04-30

411

Basic surgical techniques in the Göttingen minipig: intubation, bladder catheterization, femoral vessel catheterization, and transcardial perfusion.  

PubMed

The emergence of the Göttingen minipig in research of topics such as neuroscience, toxicology, diabetes, obesity, and experimental surgery reflects the close resemblance of these animals to human anatomy and physiology (1-6).The size of the Göttingen minipig permits the use of surgical equipment and advanced imaging modalities similar to those used in humans (6-8). The aim of this instructional video is to increase the awareness on the value of minipigs in biomedical research, by demonstrating how to perform tracheal intubation, transurethral bladder catheterization, femoral artery and vein catheterization, as well as transcardial perfusion. Endotracheal Intubation should be performed whenever a minipig undergoes general anesthesia, because it maintains a patent airway, permits assisted ventilation and protects the airways from aspirates. Transurethral bladder catheterization can provide useful information about about hydration state as well as renal and cardiovascular function during long surgical procedures. Furthermore, urinary catheterization can prevent contamination of delicate medico-technical equipment and painful bladder extension which may harm the animal and unnecessarily influence the experiment due to increased vagal tone and altered physiological parameters. Arterial and venous catheterization is useful for obtaining repeated blood samples and monitoring various physiological parameters. Catheterization of femoral vessels is preferable to catheterization of the neck vessels for ease of access, when performing experiments involving frame-based stereotaxic neurosurgery and brain imaging. When performing vessel catheterization in survival studies, strict aseptic technique must be employed to avoid infections(6). Transcardial perfusion is the most effective fixation method, and yields preeminent results when preparing minipig organs for histology and histochemistry(2,9). For more information about anesthesia, surgery and experimental techniques in swine in general we refer to Swindle 2007. Supplementary information about premedication and induction of anesthesia, assisted ventilation, analgesia, pre- and postoperative care of Göttingen minipigs are available via the internet at http://www.minipigs.com(10). For extensive information about porcine anatomy we refer to Nickel et al. Vol. 1-5(11). PMID:21730947

Ettrup, Kaare S; Glud, Andreas N; Orlowski, Dariusz; Fitting, Lise M; Meier, Kaare; Soerensen, Jens Christian; Bjarkam, Carsten R; Alstrup, Aage K Olsen

2011-01-01

412

Analysis to ventilation effectiveness in subway fire environment  

Microsoft Academic Search

When longitudinal ventilation is activated in subway station platform fire, smoke-control effectiveness depends on ventilation effectiveness. With the ventilation motion analyzed, its time at staircase is decreased and ventilation effectiveness gets better all along platform. In case of 30 MW fire with 80 m3\\/s smoke volume flow rate, longitudinal ventilation of bigger than 1.5 m\\/s freshens platform all around for

Wen-Zhong Wu; Shi-Jun You

2009-01-01

413

46 CFR 98.25-75 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk § 98.25-75 Ventilation. (a) All enclosed spaces containing cargo tanks fitted with bottom...

2012-10-01

414

46 CFR 98.25-75 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk § 98.25-75 Ventilation. (a) All enclosed spaces containing cargo tanks fitted with bottom...

2011-10-01

415

46 CFR 98.25-75 - Ventilation.  

...MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk § 98.25-75 Ventilation. (a) All enclosed spaces containing cargo tanks fitted with bottom...

2014-10-01

416

46 CFR 98.25-75 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk § 98.25-75 Ventilation. (a) All enclosed spaces containing cargo tanks fitted with bottom...

2013-10-01

417

46 CFR 98.25-75 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...MISCELLANEOUS VESSELS SPECIAL CONSTRUCTION, ARRANGEMENT, AND OTHER PROVISIONS FOR CERTAIN DANGEROUS CARGOES IN BULK Anhydrous Ammonia in Bulk § 98.25-75 Ventilation. (a) All enclosed spaces containing cargo tanks fitted with bottom...

2010-10-01

418

46 CFR 111.15-10 - Ventilation.  

...ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Storage Batteries and Battery Chargers: Construction and Installation § 111...General. Each room, locker, and box for storage batteries must be arranged or ventilated to prevent...

2014-10-01

419

EVALUATION OF VENTILATION PERFORMANCE FOR INDOOR SPACE  

EPA Science Inventory

The paper discusses a personal-computer-based application of computational fluid dynamics that can be used to determine the turbulent flow field and time-dependent/steady-state contaminant concentration distributions within isothermal indoor space. (NOTE: Ventilation performance ...

420

Midlevel Ventilation's Constraint on Tropical Cyclone Intensity  

E-print Network

Midlevel ventilation, or the flux of low-entropy air into the inner core of a tropical cyclone (TC), is a hypothesized mechanism by which environmental vertical wind shear can constrain a tropical cyclone’s intensity. An ...

Tang, Brian Hong-An

421

Tunnel ventilation effectiveness in fire scenarios   

E-print Network

Throughout most of a tunnel network the ventilation behaviour may be approximated with a simple 1D flow model. However, there are some important - but relatively small - regions of the tunnel that require CFD analysis. The multi-scale model...

Colella, Francesco; Rein, Guillermo; Carvel, Ricky O; Torero, Jose L

2010-01-01

422

14 CFR 23.831 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...sufficient amount of uncontaminated air to enable the flight crew members to perform their duties without undue discomfort or fatigue. For normal operating conditions, the ventilation system must be designed to provide each occupant with at least...

2012-01-01

423

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...HANDLING, USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-5 Ventilation. (a) Operations, reactions or experiments which produce toxic, noxious or...

2010-10-01

424

A Ventilation Index for Tropical Cyclones  

E-print Network

An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilation—or the flux of ...

Tang, Brian

425

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2010 CFR

...HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground...principal air flows; (2) Locations of seals used to isolate abandoned workings;...

2010-07-01

426

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2011 CFR

...HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground...principal air flows; (2) Locations of seals used to isolate abandoned workings;...

2011-07-01

427

30 CFR 57.8520 - Ventilation plan.  

...HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground...principal air flows; (2) Locations of seals used to isolate abandoned workings;...

2014-07-01

428

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2013 CFR

...HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground...principal air flows; (2) Locations of seals used to isolate abandoned workings;...

2013-07-01

429

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2012 CFR

...HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground...principal air flows; (2) Locations of seals used to isolate abandoned workings;...

2012-07-01

430

Midlevel ventilation's constraint on tropical cyclone intensity  

E-print Network

Midlevel ventilation, or the flux of low-entropy air into the inner core of a tropical cyclone (TC), is a hypothesized mechanism by which environmental vertical wind shear can constrain a TC's intensity. An idealized ...

Tang, Brian Hong-An

2010-01-01

431

Waste tank ventilation system waste material accumulations  

SciTech Connect

This paper calculates the amount of material that accumulates in the ventilation systems of various Tank Waste Remediation System facilities and estimates the amount of material that could be released due to a rapid pressurization.

Van Vleet, R.J., Westinghouse Hanford

1996-08-06

432

Scale model studies of displacement ventilation  

E-print Network

Displacement ventilation is an air conditioning method that provides conditioned air to indoor environments with the goal to improve air quality while reducing energy consumption. This study investigates the performance ...

Okutan, Galip Mehmet

1995-01-01

433

Sensor-based demand controlled ventilation  

SciTech Connect

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation rates are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.

De Almeida, A.T. [Universidade de Coimbra (Portugal). Dep. Eng. Electrotecnica; Fisk, W.J. [Lawrence Berkeley National Lab., CA (United States)

1997-07-01

434

Recovering Energy From Ventilation and Process Airstreams  

E-print Network

RECOVERING ENERGY FROM VENTILATION AND PROCESS AIRSTREAMS Heat Exchangers and contaminant Recovery William A. Cheney united Air Specialists, Inc. Cincinnati, Ohio The high cost of energy has prompted industry to look for new ways to reduce... operating expenses. Often ignored are the large amounts of recoverable energy present in the ventilation and process airstreams discharged from the plant. The recovery methods available range from fairly simple, well-known devices that have been around...

Cheney, W. A.

435

Lung Perfusion Scanning in Hepatic Cirrhosis  

PubMed Central

Abnormal lung perfusion scans using radioactive particles were found in five out of six cases of hepatic cirrhosis with arterial hypoxaemia. None had clinical evidence of cardiopulmonary disease or signs of pulmonary embolism on arteriography. The scan defects are probably caused by a disorder of the pulmonary microvasculature, which may show regional variation in severity. ImagesFIG. 1FIG. 2 PMID:4645896

Stanley, N. N.; Ackrill, P.; Wood, J.

1972-01-01

436

Lung perfusion imaging in small animals using 4D micro-CT at heartbeat temporal resolution  

PubMed Central

Purpose: Quantitative in vivo imaging of lung perfusion in rodents can provide critical information for preclinical studies. However, the combined challenges of high temporal and spatial resolution have made routine quantitative perfusion imaging difficult in small animals. The purpose of this work is to demonstrate 4D micro-CT for perfusion imaging in rodents at heartbeat temporal resolution and isotropic spatial resolution. Methods: We have recently developed a dual tube?detector micro-CT scanner that is well suited to capture first pass kinetics of a bolus of contrast agent used to compute perfusion information. Our approach is based on the paradigm that similar time density curves can be reproduced in a number of consecutive, small volume injections of iodinated contrast agent at a series of different angles. This reproducibility is ensured by the high-level integration of the imaging components of our system with a microinjector, a mechanical ventilator, and monitoring applications. Sampling is controlled through a biological pulse sequence implemented in LABVIEW. Image reconstruction is based on a simultaneous algebraic reconstruction technique implemented on a graphic processor unit. The capabilities of 4D micro-CT imaging are demonstrated in studies on lung perfusion in rats. Results: We report 4D micro-CT imaging in the rat lung with a heartbeat temporal resolution (approximately 150 ms) and isotropic 3D reconstruction with a voxel size of 88 ?m based on sampling using 16 injections of 50 ?L each. The total volume of contrast agent injected during the experiments (0.8 mL) was less than 10% of the total blood volume in a rat. This volume was not injected in a single bolus, but in multiple injections separated by at least 2 min interval to allow for clearance and adaptation. We assessed the reproducibility of the time density curves with multiple injections and found that these are very similar. The average time density curves for the first eight and last eight injections are slightly different, i.e., for the last eight injections, both the maximum of the average time density curves and its area under the curve are decreased by 3.8% and 7.2%, respectively, relative to the average time density curves based on the first eight injections. The radiation dose associated with our 4D micro-CT imaging is 0.16 Gy and is therefore in the range of a typical micro-CT dose. Conclusions: 4D micro-CT-based perfusion imaging demonstrated here has immediate application in a wide range of preclinical studies such as tumor perfusion, angiogenesis, and renal function. Although our imaging system is in many ways unique, we believe that our approach based on the multiple injection paradigm can be used with the newly developed flat-panel slip-ring-based micro-CT to increase their temporal resolution in dynamic perfusion studies. PMID:20175466

Badea, Cristian T.; Johnston, Samuel M.; Subashi, Ergys; Qi, Yi; Hedlund, Laurence W.; Johnson, G. Allan

2010-01-01

437

Clinical Neuroimaging Using Arterial Spin-Labeled Perfusion MRI  

PubMed Central

SUMMARY The two most common methods for measuring perfusion with MRI are based on dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL). Although clinical experience to date is much more extensive with DSC perfusion MRI, ASL methods offer several advantages. The primary advantages are that completely noninvasive absolute cerebral blood flow (CBF) measurements are possible with relative insensitivity to permeability, and that multiple repeated measurements can be obtained to evaluate one or more interventions or to perform perfusion-based functional MRI. ASL perfusion and perfusion-based fMRI methods have been applied in many clinical settings, including acute and chronic cerebrovascular disease, CNS neoplasms, epilepsy, aging and development, neurodegenerative disorders, and neuropsychiatric diseases. Recent technical advances have improved the sensitivity of ASL perfusion MRI, and increasing use is expected in the coming years. This review focuses on ASL perfusion MRI and applications in clinical neuroimaging. PMID:17599701

Wolf, Ronald L.; Detre, John A.

2007-01-01

438

Effect of hypothermic perfusion on corneal endothelial morphology.  

PubMed Central

The effect of moderate in-vivo hypothermic perfusion on corneal endothelial integrity was studied in the cat. Eleven cats underwent in-vivo anterior chamber perfusion for 30 minutes with either normothermic (23 degrees C) or hypothermic (5 degrees C) perfusate. Corneas were then evaluated clinically (biomicroscopy), functionally (vital staining), and morphologically (scanning electron microscopy) for changes attributable to hypothermic perfusion. All 3 modes of evaluation suggested no difference in corneal endothelial integrity under the 2 experimental perfusion conditions. At the clinical and scanning electron microscope levels hypothermic perfusion does not show any effects on the corneal endothelium. Regional hypothermia is of theoretical and potential utility in procedures involving prolonged intraocular perfusion. Images PMID:6671094

Mannis, M. J.; Miller, R. B.; Carlson, E. C.; Hinds, D.; May, D. R.

1983-01-01

439

Home mechanical ventilation for amyotrophic lateral sclerosis: nasal compared to tracheostomy-intermittent positive pressure ventilation  

Microsoft Academic Search

People with amyotrophic lateral sclerosis (ALS) usually die from respiratory failure unless they use mechanical ventilation (MV). Many die of respiratory failure without being adequately informed about the available options, such as MV, that can provide symptomatic relief and prolong survival. The traditional method of MV used for persons with ALS has been tracheostomy-intermittent positive pressure ventilation (IPPV). However, the

Pamela A. Cazzolli; Edward A. Oppenheimer

1996-01-01

440

Episodic ventilation lowers the efficiency of pulmonary CO2 excretion.  

PubMed

The ventilation pattern of many ectothermic vertebrates, as well as hibernating and diving endotherms, is episodic where breaths are clustered in bouts interspersed among apneas of varying duration. Using mechanically ventilated, anesthetized freshwater turtles (Trachemys scripta), a species that normally exhibits this episodic ventilation pattern, we investigated whether episodic ventilation affects pulmonary gas exchange compared with evenly spaced breaths. In two separate series of experiments (a noninvasive and an invasive), ventilation pattern was switched from a steady state, with evenly spaced breaths, to episodic ventilation while maintaining overall minute ventilation (30 ml·min(-1)·kg(-1)). On switching to an episodic ventilation pattern of 10 clustered breaths, mean CO2 excretion rate was reduced by 6 ± 5% (noninvasive protocol) or 20 ± 8% (invasive protocol) in the first ventilation pattern cycle, along with a reduction in the respiratory exchange ratio. O2 uptake was either not affected or increased in the first ventilation pattern cycle, while neither heart rate nor overall pulmonary blood flow was significantly affected by the ventilation patterns. The results confirm that, for a given minute ventilation, episodic ventilation is intrinsically less efficient for CO2 excretion, thereby indicating an increase in the total bodily CO2 store in the protocol. Despite the apparent CO2 retention, mean arterial Pco2 only increased 1 Torr during the episodic ventilation pattern, which was concomitant with a possible reduction of respiratory quotient. This would indicate a shift in metabolism such that less CO2 is produced when the efficiency of excretion is reduced. PMID:23970538

Malte, Christian Lind; Malte, Hans; Wang, Tobias

2013-11-01

441

Ventilation efficiencies of a desk-edge-mounted task ventilation system  

SciTech Connect

In chamber experiments, we investigated the effectiveness of a task ventilation system with an air supply nozzle located underneath the front edge of a desk and directing air toward a heated mannequin seated at the desk. The task ventilation system provided outside air, while another ventilation system provided additional space cooling but no outside air. Test variables included the vertical angle of air supply (-15{sup o} to 45{sup o} from horizontal), and the supply flow rate of (3.5 to 6.5 L s{sup -1}). Using the tracer gas step-up and step-down procedures, the measured air change effectiveness (i.e., exhaust air age divided by age of air at the mannequin's face) ranged from 1.4 to 2.7, which is higher than typically reported for commercially available task ventilation or displacement ventilation systems.

Faulkner, David; Fisk, William J.; Sullivan, Douglas P.; Lee, Seung Min

2002-03-01

442

Hydrostatic Hyperbaric Chamber Ventilation System  

NASA Technical Reports Server (NTRS)

The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy (HBOT) available in the developing world for the treatment of a variety of medical conditions. Specifically, HBOT is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. HBOT is simply too expensive and too dangerous to implement in the developing world using standard equipment. The HHC technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system to provide controlled pressurization and adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware, supports sustainability.

Sarguisingh, Miriam J.

2012-01-01

443

Hydrostatic Hyperbaric Chamber Ventilation System  

NASA Technical Reports Server (NTRS)

The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications, including the treatment of medical conditions. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy available in the developing world for the treatment of a variety of medical conditions. Specifically, hyperbaric oxygen therapy is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. Hyperbaric oxygen therapy is simply too expensive and too dangerous to implement in the developing world using standard equipment. The hydrostatic hyperbaric chamber technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system that will provide controlled pressurization of the system, and provide adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware, supports sustainability.

Sargusingh, Miriam M.

2011-01-01

444

The effect of mechanical ventilator settings during ventilator hyperinflation techniques: a bench-top analysis.  

PubMed

Ventilator hyperinflations are used by physiotherapists for the purpose of airway clearance in intensive care. There is limited data to guide the selection of mechanical ventilator modes and settings that may achieve desired flow patterns for ventilator hyperinflation. A mechanical ventilator was connected to two lung simulators and a respiratory mechanics monitor. Peak inspiratory (PIFR) and expiratory flow rates (PEFR) were measured during manipulation of ventilator modes (pressure support ventilation [PSV], volume-controlled synchronised intermittent mandatory ventilation [VC-SIMV] and pressure-controlled synchronised intermittent mandatory ventilation [PC-SIMV]) and ventilator settings (including set tidal volume, positive end-expiratory pressure, inspiratory flow rate, inspiratory pause, pressure support, inspiratory time and/or inflation pressure). Additionally, each trial was conducted with high (0.05 l/cmH2O) and low (0.01 l/cmH2O) compliance settings on the lung simulators. Each trial was dichotomised into success or failure under three categories (attainment of PIFR-PEFR less than or equal to 0.9, PEFR/PIFR greater than 17 l/min, PEFR greater than or equal to 40 l/min). A total of 232 trials were conducted (96 VC-SIMV, 96 PC-SIMV, 40 PSV). A greater proportion of VC-SIMV trials were ceased due to high peak inspiratory pressures (35%). However, VC-SIMV trials were more likely to be successful at meeting all three outcome measures (26 VC-SIMV trials, 7 PC-SIMV trials, 0 PSV trials). It was found that manipulation of settings in VC-SIMV mode appears more successful than PSV and PC-SIMV for ventilator hyperinflations. PMID:25579293

Thomas, P J

2015-01-01

445

WASTE HANDLING BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT  

SciTech Connect

The Waste Handling Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Handling Building (WHB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition to maintaining the proper environmental conditions for equipment operation and personnel comfort, the contamination confinement area ventilation system directs potentially contaminated air away from personnel in the WHB and confines the contamination within high-efficiency particulate air (HEPA) filtration units. The contamination confinement areas ventilation system creates airflow paths and pressure zones to minimize the potential for spreading contamination within the building. The contamination confinement ventilation system also protects the environment and the public by limiting airborne releases of radioactive or other hazardous contaminants from the WHB. The Waste Handling Building Ventilation System is designed to perform its safety functions under accident conditions and other Design Basis Events (DBEs) (such as earthquakes, tornadoes, fires, and loss of the primary electric power). Additional system design features (such as compartmentalization with independent subsystems) limit the potential for cross-contamination within the WHB. The system provides status of important system parameters and equipment operation, and provides audible and/or visual indication of off-normal conditions and equipment failures. The Waste Handling Building Ventilation System confines the radioactive and hazardous material within the building such that the release rates comply with regulatory limits. The system design, operations, and maintenance activities incorporate ALARA (as low as is reasonably achievable) principles to maintain personnel radiation doses to all occupational workers below regulatory limits and as low as is reasonably achievable. The Waste Handling Building Ventilation System interfaces with the Waste Handling Building System by being located within the WHB and by maintaining specific pressures, temperatures, and humidity within the building. The system also depends on the WHB for water supply. The system interfaces with the Site Radiological Monitoring System for continuous monitoring of the exhaust air; the Waste Handling Building Fire Protection System for detection of fire and smoke; the Waste Handling Building Electrical System for normal, emergency, and standby power; and the Monitored Geologic Repository Operations Monitoring and Control System for monitoring and control of the system.

P.A. Kumar

2000-06-21

446

WASTE TREATMENT BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT  

SciTech Connect

The Waste Treatment Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Treatment Building (WTB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition to maintaining the proper environmental conditions for personnel comfort and equipment operation, the contamination confinement area ventilation system directs potentially contaminated air away from personnel in the WTB and confines the contamination within high-efficiency particulate air (HEPA) filtration units. The contamination confinement area ventilation system creates airflow paths and pressure zones to minimize the potential for spreading contamination with the building. The contamination confinement ventilation system also protects the environment and the public by limiting airborne releases of radioactive or other hazardous contaminants from the WTB. The Waste Treatment Building Ventilation System confines the radioactive and hazardous material within the building such that the release rates comply with regulatory limits, The system design, operations, and maintenance activities incorporate ALARA (as low as is reasonably achievable) principles to maintain personnel radiation doses to all occupational workers below regulatory limits and as low as is reasonably achievable. The system provides status of important system parameters and equipment operation, and provides audible and/or visual indication of off-normal conditions and equipment failures. The Waste Treatment Building Ventilation System interfaces with the Waste Treatment Building System by being located in the WTB, and by maintaining specific pressure, temperature, and humidity environments within the building. The system also depends on the WTB for normal electric power supply and the required supply of water for heating, cooling, and humidification. Interface with the Waste Treatment Building System includes the WTB fire protection subsystem for detection of fire and smoke. The Waste Treatment Building Ventilation System interfaces with the Site Radiological Monitoring System for continuous monitoring of the exhaust air and key areas within the WTB, the Monitored Geologic Repository Operations Monitoring and Control System for monitoring and control of system operations, and the Site Generated Radiological Waste Handling System and Site Generated Hazardous, Non-Hazardous & Sanitary Waste Disposal System for routing of pretreated toxic, corrosive, and radiologically contaminated effluent from process equipment to the HEPA filter exhaust ductwork and air-cleaning unit.

P.A. Kumar

2000-06-22

447

Benchmarking mechanical ventilation services in teaching hospitals.  

PubMed

The purpose of this investigation was to examine the technical efficiency of mechanical ventilation nonsurgery (DRG 475) among University Hospital Consortium (UHC) hospitals that consists of volunteer, teaching hospitals across the nation. The data for this study was retrieved from the 1997 UHC database that includes charge and discharge information for 69 hospitals. Data on 7961 patients classified with mechanical ventilation were aggregated to the hospital level. We retained data from a total of 62 hospitals, the other seven hospitals had missing data. The research questions were (1) Do UHC hospitals differ significantly in their efficiencies in the treatment of mechanically ventilated patients? (2) What inputs and outputs contribute most to the inefficiencies associated with mechanical ventilation? Of the 62 hospitals analyzed using data envelopment analysis technique, 10 were considered efficient and 52 were inefficient as compared to their benchmark peers. Efficient and inefficient hospitals did significantly differ between the transferred output variable and between the respiratory, laboratory, and radiology input variables. All inputs demonstrated excessive resource utilization among inefficient hospitals as compared to efficient hospitals. A total reduction of about $19 million dollars in ancillary services would need to occur for inefficient hospitals to approach the frontier of efficient hospitals. This study demonstrates that mechanical ventilation is costly, yet the specified ancillary services are capable of being reduced yielding technical efficiency as demonstrated by 10 efficient hospitals. PMID:12018609

O'Neal, Pamela V; Ozcan, Yasar A; Ma, Yanqiang

2002-06-01

448

Design Feature 7: Continuous Preclosure Ventilation  

SciTech Connect

This design feature (DF) is intended to evaluate the effects of continuous ventilation in the emplacement drifts during preclosure and how the effects, if any, compare to the Viability Assessment (VA) reference design for postclosure long term performance. This DF will be evaluated against a set of criteria provided by the License Application Design Selection (LADS) group. The VA reference design included a continuous ventilation airflow quantity of 0.1 m{sup 3}/s in the emplacement drifts in the design of the repository subsurface facilities. The effects of this continuous ventilation during the preclosure was considered to have a negligible effect on postclosure performance and therefore is not included during postclosure in the assessment of the long term performance. This DF discusses the effects of continuous ventilation on the emplacement drift environment and surrounding rock conditions during preclosure for three increased airflow quantities. The three cases of continuous ventilation systems are: System A, 1.0 m{sup 3}/s (Section 8), System B, 5.0 m{sup 3}/s (Section 9), and System C, 10.0 m{sup 3}/s (Section 10) in each emplacement drift split. An emplacement drift split is half total length of emplacement drift going from the east or west main to the exhaust main. The difference in each system is the quantity of airflow in the emplacement drifts.

A.T. Watkins

1999-06-22

449

Imaging of drug effects in perfused liver  

NASA Astrophysics Data System (ADS)

Various medications affect the systemic circulation and organ oxygenation causing dilatation or constriction of blood vessels. Imminent liver failure can be generated by reduced perfusion of different origins. In this case hepatic vasodilatation would be a therapeutical approach for improving patient's condition. Our examinations have been performed in perfused rat liver using spectrometric methods. Two defined areas of the liver were measured punctually. We compared the influence of Tetramethylpyrazine and Glyceroltrinitrate on hemoglobin oxygenation (HbO2) and concentration (Hb-conc.) in rat liver after application of Norepinephrine, which caused a mid decrease in hemoglobin oxygenation of 47,9 %. Both increased the HbO2, but differed from each other in manner of time and extent. Tetramethylpyrazine indicated a longer effect than Glyceroltrinitrate. Furthermore, HbO2 and Hb-conc. showed a conversed relation. From the shape of the absorption spectra it is possible to derive the oxygenation of hemoglobin.

Dammann, Marc; Mahlke, Christine; Kessler, Manfred D.

2002-06-01

450

Visual analysis of longitudinal brain tumor perfusion  

NASA Astrophysics Data System (ADS)

In clinical research on diagnosis and evaluation of brain tumors, longitudinal perfusion MRI studies are acquired for tumor grading as well as to monitor and assess treatment response and patient prognosis. Within this work, we demonstrate how visual analysis techniques can be adapted to multidimensional datasets from such studies within a framework to support the computer-aided diagnosis of brain tumors. Our solution builds on two innovations: First, we introduce a pipeline yielding comparative, co-registered quantitative perfusion parameter maps over all time steps of the longitudinal study. Second, based on these time-dependent parameter maps, visual analysis methods were developed and adapted to reveal valuable insight into tumor progression, especially regarding the clinical research area of low grade glioma transformation into high grade gliomas. Our examination of four longitudinal brain studies demonstrates the suitability of the presented visual analysis methods and comprises new possibilities for the clinical researcher to characterize the development of low grade gliomas.

Glaßer, Sylvia; Oeltze, Steffen; Preim, Uta; Bjørnerud, Atle; Hauser, Helwig; Preim, Bernhard

2013-02-01

451

Magnetic resonance imaging evaluation of myocardial perfusion.  

PubMed

Noninvasive qualitative/quantitative assessment of myocardial perfusion is considered to be fundamental in the management of known and suspected coronary artery disease patients, as shown by the widespread utilization of thallium-201- and technetium-99m-labeled agents in myocardial single-photon emission computed tomography (SPECT) scintigraphy for diagnostic as well as prognostic purposes. Recently, the availability of subsecond ultrafast magnetic resonance imaging (MRI) sequences (FLASH, TurboFLASH, EPI) has provided new avenues for assessing myocardial perfusion by MRI in conjunction with contrast-agent bolus administration (contrast-enhanced first-pass MRI). MRI contrast agents can be classified into relaxation agents (T1 "positive") and susceptibility agents (T2 star [T2*] "negative"). All the commercially available MRI contrast agents used in clinical practice are relaxation agents employing the T1 shortening effect of metal ions like gadolinium (paramagnetism), thus producing a tissue signal-intensity increase on T1-weighted images (positive enhancement). On the other hand, T2* agents induce mainly susceptibility effects, i.e., rapid dephasing of spins with resultant signal loss on T2*-sensitive sequences (negative enhancement). Unfortunately, both relaxation and susceptibility agents are, by definition, "extracellular" contrast media, as they rapidly diffuse into the interstitial space, thus hampering the simple application of indicator-dilution kinetics for myocardial perfusion assessment. Blood pool agents are therefore needed to obtain predictable relations between the concentration of contrast medium in the myocardium and the change in signal intensity. In addition, newer MRI techniques for tissue perfusion quantitation have been recently reported, based on blood-sensitive sequences, thus without intravenous contrast administration. PMID:9662231

Passariello, R; De Santis, M

1998-06-18

452

Efficacy of intermittent ventilation for providing acceptable indoor air quality  

SciTech Connect

Ventilation standards and guidelines typically treat ventilation as a constant and specify its value. In many circumstances a designer wishes to use intermittent ventilation, rather than constant ventilation, but there are no easy equivalencies available. This report develops a model of efficacy that allows one to calculate how much intermittent ventilation one needs to get the same indoor air quality as a the continuous value specified. We have found that there is a simple relationship between three dimensionless quantities: the temporal ventilation effectiveness (which we call the efficacy), the nominal turn-over and the under-ventilation fraction. This relationship allows the calculation of intermittent ventilation for a wide variety of parameters and conditions. We can use the relationship to define a critical time that separates the regime in which ventilation variations can be averaged over from the regime in which variable ventilation is of low effectiveness. We have found that ventilation load-shifting, temporary protection against poor outdoor air quality and dynamic ventilation strategies can be quite effective in low-density buildings such as single-family houses or office spaces. The results of this work enable ventilation standards and guidelines to allow this extra flexibility and still provide acceptable indoor air quality.

Sherman, M.H.

2004-10-01

453

[Extracorporeal gas exchange--an alternative to ventilation of the premature newborn infant with respiratory insufficiency].  

PubMed

In spite of improvements in its prophylaxis and therapy the membrane syndrome is still one of the main causes of morbidity and mortality in newborns. In many perinatal centers in the United States extracorporeal gas exchange via an artificial lung is the ultimate step in therapy for this group of patients today. As a result of our own research work we are able to introduce an extracorporeal circulation system which is especially suited to the particular situation of the immature newborn and which enables a complete immobilization of the lung to avoid baro-trauma with alveolar oxygen diffusion and CO2-removal through the membrane lung. Using appropriate dimensions the system can be housed in a newborn incubator. With low total resistance the perfusion in the newborn is performed via an arterio-venous shunt of the umbilical vessels alternatively with and without a mechanical pump. We tested this perfusion system on premature lambs with a gestational age of 128 to 130 days. During a test period of from 6 to 8 hours at a low blood flow rate (200 ml/min) we achieved a sufficient CO2-removal via the membrane lung with enough oxygen supply through the non-ventilated lung. By means of suitable materials, and using CO2 gas priming procedure and employing prostacyclin analogons to inhibit thrombocyte aggregation, it was possible to lower the heparine dosage to a minimum. PMID:6591629

Schmidt, S; Dudenhausen, J W; Langner, K; Laiblin, C; Saling, E

1984-01-01

454

Inhomogeneity of pulmonary perfusion during sustained microgravity  

NASA Technical Reports Server (NTRS)

The effects of gravity on the inhomogeneity of pulmonary perfusion in man were studied by performing hyperventilation-breathhold single-breath measurements before, during and after 9 days of continuous exposure to microgravity. In microgravity the indicators of inhomogeneity of perfusion, especially the size of cardiogenic oscillations in expired CO2 and the height of phase 4, were both markedly reduced. Cardiogenic oscillations were reduced to approximately 60 of their preflight standing size, while the height of phase 4 was between 0 and -8% (a terminal fall became a small terminal rise) of preflights standing. The terminal change in CO2 was nearly abolished in microgravity indicating more uniformity of blood flow between lung units that close at the end of expiration and units that remain open. This may result from the disappearance of gravity-dependent topographical inequality of blood flow. The residual cardiographic oscillations in expired CO2 imply a persisting inhomogeneity of perfusion in the absence of gravity at a level larger than acinar.

Prisk, G. Kim; Guy, Harold J. B.; Elliott, Ann R.; West, John B.

1994-01-01

455

CT perfusion: principles, applications, and problems  

NASA Astrophysics Data System (ADS)

The fast scanning speed of current slip-ring CT scanners has enabled the development of perfusion imaging techniques with intravenous injection of contrast medium. In a typical CT perfusion study, contrast medium is injected and rapid scanning at a frequency of 1-2 Hz is used to monitor the first circulation of the injected contrast medium through a 1-2 cm thick slab of tissue. From the acquired time-series of CT images, arteries can be identified within the tissue slab to derive the arterial contrast concentration curve, Ca(t) while each individual voxel produces a tissue residue curve, Q(t) for the corresponding tissue region. Deconvolution between the measured Ca(t) and Q(t) leads to the determination of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in brain studies. In this presentation, an important application of CT perfusion in acute stroke studies - the identification of the ischemic penumbra via the CBF/CBV mismatch and factors affecting the quantitative accuracy of deconvolution, including partial volume averaging, arterial delay and dispersion are discussed.

Lee, Ting-Yim

2004-10-01

456

Regulation of skeletal muscle perfusion during exercise  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

457

30 CFR 57.8531 - Construction and maintenance of ventilation doors.  

Code of Federal Regulations, 2013 CFR

...Construction and maintenance of ventilation doors. 57.8531 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8531 Construction and maintenance of ventilation doors. Ventilation doors...

2013-07-01

458

30 CFR 57.8531 - Construction and maintenance of ventilation doors.  

Code of Federal Regulations, 2010 CFR

...Construction and maintenance of ventilation doors. 57.8531 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8531 Construction and maintenance of ventilation doors. Ventilation doors...

2010-07-01

459

30 CFR 57.8531 - Construction and maintenance of ventilation doors.  

Code of Federal Regulations, 2012 CFR

...Construction and maintenance of ventilation doors. 57.8531 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8531 Construction and maintenance of ventilation doors. Ventilation doors...

2012-07-01

460

30 CFR 57.8531 - Construction and maintenance of ventilation doors.  

Code of Federal Regulations, 2011 CFR

...Construction and maintenance of ventilation doors. 57.8531 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8531 Construction and maintenance of ventilation doors. Ventilation doors...

2011-07-01

461

30 CFR 57.8531 - Construction and maintenance of ventilation doors.  

...Construction and maintenance of ventilation doors. 57.8531 Section 57...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Underground Only § 57.8531 Construction and maintenance of ventilation doors. Ventilation doors...

2014-07-01

462

Phase imbalance on ComEd`s transmission and distribution systems  

SciTech Connect

Railroad rights-of-way are fast becoming the only alternative for construction of new transmission facilities. It is essential to provide correct and comprehensive information on expected EMF levels to consultants and railroads for inductive coordination. While techniques are proven and readily available to model the fields near transmission lines, the phase imbalance typical for various installations has never been accurately characterized at ComEd. These phase imbalances can have a very significant effect on the magnetic field density resulting from the lines. Typical values of phase imbalance for 345kV, 138kV, 34kV and 12kV lines, and the methodology for determining them are presented.

Cramer, B.S. [ComEd, Chicago, IL (United States)

1995-09-01

463

MODELING VENTILATION SYSTEM RESPONSE TO FIRE  

SciTech Connect

Fires in facilities containing nuclear material have the potential to transport radioactive contamination throughout buildings and may lead to widespread downwind dispersal threatening both worker and public safety. Development and implementation of control strategies capable of providing adequate protection from fire requires realistic characterization of ventilation system response which, in turn, depends on an understanding of fire development timing and suppression system response. This paper discusses work in which published HEPA filter data was combined with CFAST fire modeling predictions to evaluate protective control strategies for a hypothetical DOE non-reactor nuclear facility. The purpose of this effort was to evaluate when safety significant active ventilation coupled with safety class passive ventilation might be a viable control strategy.

Coutts, D

2007-04-17

464

Perfusion phantom: An efficient and reproducible method to simulate myocardial first-pass perfusion measurements with cardiovascular magnetic resonance.  

PubMed

The aim of this article is to describe a novel hardware perfusion phantom that simulates myocardial first-pass perfusion allowing comparisons between different MR techniques and validation of the results against a true gold standard. MR perfusion images were acquired at different myocardial perfusion rates and variable doses of gadolinium and cardiac output. The system proved to be sensitive to controlled variations of myocardial perfusion rate, contrast agent dose, and cardiac output. It produced distinct signal intensity curves for perfusion rates ranging from 1 to 10 mL/mL/min. Quantification of myocardial blood flow by signal deconvolution techniques provided accurate measurements of perfusion. The phantom also proved to be very reproducible between different sessions and different operators. This novel hardware perfusion phantom system allows reliable, reproducible, and efficient simulation of myocardial first-pass MR perfusion. Direct comparison between the results of image-based quantification and reference values of flow and myocardial perfusion will allow development and validation of accurate quantification methods. PMID:22532435

Chiribiri, Amedeo; Schuster, Andreas; Ishida, Masaki; Hautvast, Gilion; Zarinabad, Niloufar; Morton, Geraint; Otton, James; Plein, Sven; Breeuwer, Marcel; Batchelor, Philip; Schaeffter, Tobias; Nagel, Eike

2013-03-01

465

Effects of variation in perfusion rates and of perfusion models in computational models of radio frequency tumor ablation  

PubMed Central

Purpose: Finite element method (FEM) models are commonly used to simulate radio frequency (RF) tumor ablation. Prior FEM models of RF ablation have either ignored the temperature dependent effect of microvascular perfusion, or implemented the effect using simplified algorithms to reduce computational complexity. In this FEM modeling study, the authors compared the effect of different microvascular perfusion algorithms on ablation zone dimensions with two commercial RF electrodes in hepatic tissue. They also examine the effect of tissue type and inter-patient variation of perfusion on ablation zone dimensions. Methods and Materials: The authors created FEM models of an internally cooled and multi-tined expandable electrode. RF voltage was applied to both electrodes (for 12 or 15 min, respectively) such that the maximum temperature in the model was 105 °C. Temperature dependent microvascular perfusion was implemented using three previously reported methodologies: cessation above 60 °C, a standard first-order Arrhenius model with decreasing perfusion with increasing degree of vascular stasis, and an Arrhenius model that included the effects of increasing perfusion at the ablation zone boundary due to hyperemia. To examine the effects of interpatient variation, simulations were performed with base line and ±1 standard deviation values of perfusion. The base line perfusion was also varied to simulate the difference between normal and cirrhotic liver tissue. Results: The ablation zone volumes with the cessation above 60 °C perfusion algorithm and with the more complex Arrhenius model were up to 70% and 25% smaller, respectively, compared to the standard Arrhenius model. Ablation zone volumes were up to ?175% and ?100% different between the simulations where ?1 and +1 standard deviation values of perfusion were used in normal and cirrhotic liver tissue, respectively. Conclusions: The choice of microvascular perfusion algorithm has significant effects on final ablation zone dimensions in FEM models of RF ablation. The authors also found that both interpatient variation in base line tissue perfusion and the reduction in perfusion due to cirrhosis have considerable effect on ablation zone dimensions. PMID:18777906

Schutt, David J.; Haemmerich, Dieter

2008-01-01

466

A direct comparison of the sensitivity of CT and MR cardiac perfusion using a myocardial perfusion phantom  

PubMed Central

Background Direct comparison of CT and magnetic resonance (MR) perfusion techniques has been limited and in vivo assessment is affected by physiological variability, timing of image acquisition, and parameter selection. Objective We precisely compared high-resolution k-t SENSE MR cardiac perfusion at 3 T with single-phase CT perfusion (CTP) under identical imaging conditions. Methods We used a customized MR imaging and CT compatible dynamic myocardial perfusion phantom to represent the human circulation. CT perfusion studies were performed with a Philips iCT (256 slice) CT, with isotropic resolution of 0.6 mm3. MR perfusion was performed with k-t SENSE acceleration at 3 T and spatial resolution of 1.2 × 1.2 × 10 mm. The image contrast between normal and underperfused myocardial compartments was quantified at various perfusion and photon energy settings. Noise estimates were based on published clinical data. Results Contrast by CTP highly depends on photon energy and also timing of imaging within the myocardial perfusion upslope. For an identical myocardial perfusion deficit, the native image contrast-to-noise ratio (CNR) generated by CT and MR are similar. If slice averaging is used, the CNR of a perfusion deficit is expected to be greater for CTP than MR perfusion (MRP). Perfect timing during single time point CTP imaging is difficult to achieve, and CNR by CT decreases by 24%–31% two seconds from the optimal imaging time point. Although single-phase CT perfusion offers higher spatial resolution, MRP allows multiple time point sampling and quantitative analysis. Conclusion The ability of CTP and current optimal MRP techniques to detect simulated myocardial perfusion deficits is similar. PMID:23622506

Otton, James; Morton, Geraint; Schuster, Andreas; Bigalke, Boris; Marano, Riccardo; Olivotti, Luca; Nagel, Eike; Chiribiri, Amedeo

2013-01-01

467

Regenerative Blower for EVA Suit Ventilation Fan  

NASA Technical Reports Server (NTRS)

Portable life support systems in future space suits will include a ventilation subsystem driven by a dedicated fan. This ventilation fan must meet challenging requirements for pressure rise, flow rate, efficiency, size, safety, and reliability. This paper describes research and development that showed the feasibility of a regenerative blower that is uniquely suited to meet these requirements. We proved feasibility through component tests, blower tests, and design analysis. Based on the requirements for the Constellation Space Suit ventilation fan, we designed the critical elements of the blower. We measured the effects of key design parameters on blower performance using separate effects tests, and used the results of these tests to design a regenerative blower that will meet the ventilation fan requirements. We assembled a proof-of-concept blower and measured its performance at low pressures that simulate a PLSS environment. We obtained head/flow performance curves over a range of operating speeds, identified the maximum efficiency point for the blower, and used these results to specify the design and operating conditions for the ventilation fan. We designed a compact motor that can drive the blower under all anticipated operating requirements and operate with high efficiency during normal operation. We identified materials for the blower that will enhance safety for operation in a lunar environment. We produced a solid model that illustrates the final design. The proof-of-concept blower produced the flow rate and pressure rise needed for the CSSS ventilation subsystem while running at 5400 rpm and consuming only 9 W of electric power and using a non-optimized, commercial motor and controller and inefficient bearings. Scaling the test results to a complete design shows that a lightweight, compact, reliable, and low power blower can meet the performance requirements for future PLSSs.

Paul, Heather; Izenson, Mike; Chen, Weibo

2008-01-01

468

Towards robust deconvolution of low-dose perfusion CT: sparse perfusion deconvolution using online dictionary learning.  

PubMed

Computed tomography perfusion (CTP) is an important functional imaging modality in the evaluation of cerebrovascular diseases, particularly in acute stroke and vasospasm. However, the post-processed parametric maps of blood flow tend to be noisy, especially in low-dose CTP, due to the noisy contrast enhancement profile and the oscillatory nature of the results generated by the current computational methods. In this paper, we propose a robust sparse perfusion deconvolution method (SPD) to estimate cerebral blood flow in CTP performed at low radiation dose. We first build a dictionary from high-dose perfusion maps using online dictionary learning and then perform deconvolution-based hemodynamic parameters estimation on the low-dose CTP data. Our method is validated on clinical data of patients with normal and pathological CBF maps. The results show that we achieve superior performance than existing methods, and potentially improve the differentiation between normal and ischemic tissue in the brain. PMID:23542422

Fang, Ruogu; Chen, Tsuhan; Sanelli, Pina C

2013-05-01

469

Ethical and legal implications of elective ventilation and organ transplantation: "medicalization" of dying versus medical mission.  

PubMed

A critical controversy surrounds the type of allowable interventions to be carried out in patients who are potential organ donors, in an attempt to improve organ perfusion and successful transplantation. The main goal is to transplant an organ in conditions as close as possible to its physiological live state. "Elective ventilation" (EV), that is, the use of ventilation for the sole purpose of retrieving the organs of patients close to death, is an option which offsets the shortage of organ donation. We have analyzed the legal context of the dying process of the organ donor and the feasibility of EV in the Italian context. There is no legal framework regulating the practice of EV, neither is any real information given to the general public. A public debate has yet to be initiated. In the Italian cultural and legislative scenario, we believe that, under some circumstances (i.e., the expressed wishes of the patient, even in the form of advance directives), the use of EV does not violate the principle of beneficence. We believe that the crux of the matter lies in the need to explore the real determination and will of the patient and his/her orientation towards the specific aim of organ donation. PMID:25126582

Frati, Paola; Fineschi, Vittorio; Gulino, Matteo; Montanari Vergallo, Gianluca; Di Luca, Natale Mario; Turillazzi, Emanuela

2014-01-01

470

Ethical and Legal Implications of Elective Ventilation and Organ Transplantation: “Medicalization” of Dying versus Medical Mission  

PubMed Central

A critical controversy surrounds the type of allowable interventions to be carried out in patients who are potential organ donors, in an attempt to improve organ perfusion and successful transplantation. The main goal is to transplant an organ in conditions as close as possible to its physiological live state. “Elective ventilation” (EV), that is, the use of ventilation for the sole purpose of retrieving the organs of patients close to death, is an option which offsets the shortage of organ donation. We have analyzed the legal context of the dying process of the organ donor and the feasibility of EV in the Italian context. There is no legal framework regulating the practice of EV, neither is any real information given to the general public. A public debate has yet to be initiated. In the Italian cultural and legislative scenario, we believe that, under some circumstances (i.e., the expressed wishes of the patient, even in the form of advance directives), the use of EV does not violate the principle of beneficence. We believe that the crux of the matter lies in the need to explore the real determination and will of the patient and his/her orientation towards the specific aim of organ donation. PMID:25126582

Frati, Paola; Montanari Vergallo, Gianluca; Di Luca, Natale Mario; Turillazzi, Emanuela

2014-01-01

471

Brain perfusion monitoring with frequency-domain and continuous-wave near-infrared spectroscopy: a cross-correlation study in newborn piglets  

NASA Astrophysics Data System (ADS)

The newborn piglet brain model was used to correlate continuous-wave (CW) and frequency-domain (FD) near-infrared spectroscopy. Six ventilated and instrumented newborn piglets were subjected to a series of manipulations in blood oxygenation with the effects on brain perfusion known to be associated with brain hypoxia-ischaemia. An excellent agreement between the CW and FD was demonstrated. This agreement improved when the scattering properties (determined by the FD device) were employed to calculate the differential pathlength factor, an important step in CW data processing.

Zhang, G.; Katz, A.; Alfano, R. R.; Kofinas, A. D.; Kofinas, D. A.; Stubblefield, P. G.; Rosenfeld, W.; Beyer, D.; Maulik, D.; Stankovic, M. R.

2000-11-01

472

46 CFR 108.181 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2013 CFR

...108.181 Section 108.181 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Ventilation § 108.181 Ventilation for...

2013-10-01

473

46 CFR 108.185 - Ventilation for enclosed classified locations.  

...108.185 Section 108.185 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Ventilation § 108.185 Ventilation for...

2014-10-01

474

46 CFR 108.185 - Ventilation for enclosed classified locations.  

Code of Federal Regulations, 2010 CFR

...108.185 Section 108.185 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Ventilation § 108.185 Ventilation for...

2010-10-01

475

Review: Artifical ventilation with positive end-expiratory pressure (PEEP)  

Microsoft Academic Search

CPPV (continuous positive pressure ventilation) is obviously superior to IPPV (intermittent positive pressure ventilation) for the treatment of patients with acute respiratory insufficiency (ARI) and results within a few minutes in a considerable increase in the oxygen transport.

Dag Berger Stokke

1976-01-01

476

Post-Polio Health International including International Ventilator Users Network  

MedlinePLUS

... post-polio.org. Check out International Ventilator Users Network Post-Polio Health International's mission is to enhance ... Polio Health International (PHI) Including International Ventilator Users Network 4207 Lindell Blvd., #110, Saint Louis, MO 63108- ...

477

Study on Influencing Factors of Night Ventilation in Office Rooms  

E-print Network

A mathematical and physical model on night ventilation is set up. The fields of indoor air temperature, air velocity and thermal comfort are simulated using Airpak software. Some main influencing factors of night ventilation in office rooms...

Wang, Z.; Sun, X.

2006-01-01

478

Energy Saving Guidelines for Portland State University Heating and Ventilation  

E-print Network

Energy Saving Guidelines for Portland State University Heating and Ventilation Conditioned spaces. Building ventilation will be based on actual use of the space, as determined by Academic Schedules, Posted

Caughman, John

479

3. LEPLEY VENTILATOR FROM EAST. STEAM ENGINE CYLINDER AT LEFT, ...  

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

3. LEPLEY VENTILATOR FROM EAST. STEAM ENGINE CYLINDER AT LEFT, AEROVANE FAN HOOD AT RIGHT REAR. - Consolidation Coal Company Mine No. 11, Lepley Ventilator, East side of State Route 936, Midlothian, Allegany County, MD

480

2. BRICK END ELEVATION WITH X VENTILATORS, REDPAINTED GABLE WITH ...  

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

2. BRICK END ELEVATION WITH X VENTILATORS, RED-PAINTED GABLE WITH WHITE STARS AND A DOORWAY HOOD. ALSO SHOWS PORTION OF REAR ELEVATION WITH X VENTILATORS - Decorated Red Barn (1852), State Route 100 vicinity, Pottstown, Montgomery County, PA

481

A scale model study of displacement ventilation with chilled ceilings  

E-print Network

Displacement ventilation is a form of air-conditioning which provides good air quality and some energy savings. The air quality is better than for a conventional mixed ventilation system. The maximum amount of cooling that ...

Holden, Katherine J. A. (Katherine Joan Adrienne)

1995-01-01

482

Design of a Natural Ventilation System in the Dunhuang Museum  

E-print Network

that also meets architectural standards. Natural ventilation design methods are presented in this paper. A natural ventilation system is designed in the DunHuang museum. Thermal dynamic simulation and CFD simulation were analyzed in the exhibition hall...

Zhang, Y.; Guan, W.

2006-01-01

483

Study of natural ventilation in buildings with large eddy simulation  

E-print Network

With the discovery of many economic, environmental, and health problems in sealed and mechanically ventilated buildings, the concept of natural ventilation has been revived. "Buildings that breathe" have become more and ...

Jiang, Yi, 1972-

2002-01-01

484

12. NEW YORK SIDE, HUDSON RIVER VENTILATION BUILDING IN FOREGROUND; ...  

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

12. NEW YORK SIDE, HUDSON RIVER VENTILATION BUILDING IN FOREGROUND; NEW JERSEY SIDE, HUDSON RIVEN VENTILATION BUILDING IN BACKGROUND - Holland Tunnel, Beneath Hudson River between New York & Jersey City, New York, New York County, NY

485

Indoor Air Quality: Is Increased Ventilation the Answer?  

ERIC Educational Resources Information Center

Explains how indoor air quality is affected by pollutants in the air and also by temperature, humidity, and ventilation. Increased ventilation alone seldom solves the "sick building syndrome." Lists ways to improve indoor air quality and optimize energy efficiency. (MLF)

Hansen, Shirley

1989-01-01

486

30 CFR 57.14213 - Ventilation and shielding for welding.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Ventilation and shielding for welding. 57.14213 Section 57.14213 Mineral Resources...Procedures § 57.14213 Ventilation and shielding for welding. (a) Welding operations shall be shielded when performed at...