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1

EFFECT OF VENTILATION AND PERFUSION IMBALANCE ON INERT GAS REBREATHING VARIABLES  

EPA Science Inventory

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

2

Pulmonary perfusion ''without ventilation''  

SciTech Connect

An 88-yr-old man, with prior left upper lobectomy and phrenic nerve injury, had a ventilation/perfusion lung image. Both wash-in and equilibrium ventilation images showed no radioactive gas in the left lung. Nevertheless, the left lung was perfused. A similar result was obtained on a repeat study 8 days later. Delayed images, during washout, showed some radioactive gas in the left lung. Nearly absent ventilation (but continued perfusion) of that lung might have been related to altered gas dynamics brought about by the prior lobectomy, a submucosal bronchial lesion, phrenic nerve damage, and limited motion of the left part of the diaphragm. This case raises the issue of the degree of ventilation (and the phase relationship between the lungs) required for the entry of radioactive gas into a diseased lung, and the production of a ''reversed ventilation/perfusion mismatch.''

Chapman, C.N.; Sziklas, J.J.; Spencer, R.P.; Rosenberg, R.J.

1983-12-01

3

Lung Ventilation/Perfusion Scan  

MedlinePLUS

... ventilation and perfusion. The ventilation scan shows where air flows in your lungs. The perfusion scan shows where ... body use the energy to create images of air and blood flow patterns in your lungs. Outlook VQ scans involve ...

4

Ventilation-perfusion imaging in pulmonary papillomatosis  

SciTech Connect

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

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

1981-11-01

5

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

6

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

7

Ventilation and perfusion magnetic resonance imaging of the lung  

PubMed Central

Summary A close interaction between the respiratory pump, pulmonary parenchyma and blood circulation is essential for a normal lung function. Many pulmonary diseases present, especially in their initial phase, a variable regional impairment of ventilation and perfusion. In the last decades various techniques have been established to measure the lung function. Besides the global pulmonary function tests (PFTs) imaging techniques gained increasing importance to detect local variations in lung function, especially for ventilation and perfusion assessment. Imaging modalities allow for a deeper regional insight into pathophysiological processes and enable improved planning of invasive procedures. In contrast to computed tomography (CT) and the nuclear medicine techniques, magnetic resonance imaging (MRI), as a radiation free imaging modality gained increasing importance since the early 1990 for the assessment of pulmonary function. The major inherent problems of lung tissue, namely the low proton density and the pulmonary and cardiac motion, were overcome in the last years by a constant progress in MR technology. Some MR techniques are still under development, a process which is driven by scientific questions regarding the physiology and pathophysiology of pulmonary diseases, as well as by the need for fast and robust clinically applicable imaging techniques as safe therapy monitoring tools. MRI can be considered a promising ionizing-free alternative to techniques like CT or nuclear medicine techniques for the evaluation of lung function. The goal of this article is to provide an overview on selected MRI techniques for the assessment of pulmonary ventilation and perfusion. PMID:22802864

Bauman, Grzegorz; Eichinger, Monika

2012-01-01

8

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

9

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

10

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

11

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

12

Lung Ventilation\\/Perfusion SPECT: The Right Technique for Hard Times  

Microsoft Academic Search

One of the main problems encoun- tered in the analysis of ventilation\\/per- fusion (V\\/P) lung scans for the diag- nosis of pulmonary embolism (PE) is difficulty in assessing the size of the perfusion defect, which then influences the probabilistic classification de- scribed in the Prospective Investiga- tion of Pulmonary Embolism Diagno- sis (PIOPED) study (1). In the original study, high

Michel A. Meignan; Hôpital Henri Mondor

13

Prediction of postoperative pulmonary function following thoracic operations. Value of ventilation-perfusion scanning  

SciTech Connect

Surgical resection of lung cancer is frequently required in patients with severely impaired lung function resulting from chronic obstructive pulmonary disease. Twenty patients with obstructive lung disease and cancer (mean preoperative forced expiratory volume in 1 second (FEV1) . 1.73 L) were studied preoperatively and postoperatively by spirometry and radionuclide perfusion, single-breath ventilation, and washout techniques to test the ability of these methods to predict preoperatively the partial loss of lung function by the resection. Postoperative FEV1 and forced vital capacity (FVC) were accurately predicted by the formula: postoperative FEV1 (or FVC) . preoperative FEV1 X percent function of regions of lung not to be resected (r . 0.88 and 0.95, respectively). Ventilation and perfusion scans are equally effective in prediction. Washout data add to the sophistication of the method by permitting the qualitative evaluation of ventilation during tidal breathing. Criteria for patients requiring the study are suggested.

Bria, W.F.; Kanarek, D.J.; Kazemi, H.

1983-08-01

14

Evaluation of pulmonary perfusion in lung regions showing isolated xenon-133 ventilation washout defects  

SciTech Connect

Xenon-133 washout phase imaging is often used to help determine whether the etiology of a perfusion defect is embolic or due to pulmonary parenchymal pathology, such as chronic obstructive pulmonary disease. This study was designed to evaluate the pulmonary blood flow patterns associated with isolated defects on xenon washout images. Scintigraphic lung studies were reviewed until 100 cases with abnormal ventilation results were obtained. Ventilation abnormalities were compared with the corresponding perfusion scan results at the same anatomic site. Of the 208 individual lung regions with xenon abnormalities, 111 showed isolated washout defects (that is, with normal washin). Ninety-four of these 111 sites showed either normal perfusion or a small, nonsegmental corresponding perfusion defect. Three segmental perfusion defects were noted in association with isolated xenon retention. In each of these cases, however, the patient was felt actually to have pulmonary embolism. Thus, it is recommended that, for interpretation of scintigraphic images in the assessment of pulmonary embolism, lung pathology associated with isolated xenon retention not be considered a potential cause for large or segmental perfusion defects.

Bushnell, D.L.; Sood, K.B.; Shirazi, P.; Pal, I. (VA Hines Hospital, IL (USA))

1990-08-01

15

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

16

Validation of a two-compartment model of ventilation\\/perfusion distribution  

Microsoft Academic Search

Ventilation (V?A) to perfusion (Q?) heterogeneity (V?A\\/Q?) analyses by a two-compartment lung model (2C), utilizing routine gas exchange measurements and a computer solution to account for O2 and CO2 measurements, were compared with multiple inert gas elimination technique (MIGET) analyses and a multi-compartment (MC) model. The 2C and MC estimates of V?A\\/Q? mismatch were obtained in 10 healthy subjects, 43

Jack A. Loeppky; Arvind Caprihan; Stephen A. Altobelli; Milton V. Icenogle; Pietro Scotto; Marcos F. Vidal Melo

2006-01-01

17

Deep Hypothermic Circulatory Arrest with Lung Perfusion/Ventilation in a Patient with Acute Type A Aortic Dissection  

PubMed Central

A 50-year-old black male presented with acute type A aortic dissection. Surgical repair was performed under deep hypothermic circulatory arrest (DHCA) with lung perfusion/ventilation throughout the procedure. Details of the lung perfusion technique and its potential benefits and drawbacks are discussed. PMID:22474459

Rodriguez-Blanco, Yiliam F.; Garcia, Lester; Brice, Tania; Ricci, Marco; Salerno, Tomas A.

2012-01-01

18

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

19

The matching of ventilation and perfusion in the lung of the Tegu lizard, Tupinambis nigropunctatus.  

PubMed

Ventilation-perfusion (VA/Q) distribution was evaluated in the Tegu lizard, Tupinambis nigropunctatus, using the multiple inert gas elimination technique (MIGET) in order to define the limitations to gas exchange in the large chambered unicameral lung. The lizards (0.52-1.1 kg) were anesthetized with halothane and ventilated. Body temperature was maintained at 35 degrees C. Arterial and sinus venosus PO2 averaged 79.4 +/- 5.9 and 47.3 +/- 6.4 torr while breathing air and 232.1 +/- 31 and 64.8 +/- 11.5 torr while breathing oxygen. VA/Q distributions were broad and right-to-left shunt averaged 21% while breathing air and 27% while breathing oxygen. Gas exchange was significantly impaired due to the presence of both shunt and VA/Q heterogeneity. The walls of the lung enclose a large axial air chamber. Microscopic examination revealed approximately three generations of septa which subdivided the wall into tubular-shaped gas-exchange chambers. Wall thickness averages 2.8 mm at the anterior end of the lung, 2.1 mm in the middle portion of the lung and 1.4 mm at the posterior end. The thickness of the blood-air barrier (epithelial-basal lamina-endothelial cell layer) ranged from 0.35 to 0.90 micron. Although this barrier is slightly thicker than in the mammalian lung (0.1-0.5 micron), it is unlikely to be a source of diffusion limitation in gas exchange at rest. PMID:4035106

Hlastala, M P; Standaert, T A; Pierson, D J; Luchtel, D L

1985-06-01

20

A novel quantitative dual-isotope method for simultaneous ventilation and perfusion lung SPET.  

PubMed

A quantitative dual-isotope single-photon emission tomography (SPET) technique for the assessment of lung ventilation (V) and perfusion (Q) using, respectively, technetium-99m labelled Technegas (140 keV) and indium-113m labelled macro-aggregated albumin (392 keV), is presented, validated and clinically tested in a healthy volunteer. In order to assess V, Q and V/Q distributions in quantitative terms, algorithms which correct for down scattering, photon scattering and attenuation, as well as an organ outline algorithm, were implemented. Scatter and down-scatter correction were made in the spatial domain by pixel-wise image subtraction of projection-dependent global scattering factors obtained from the energy domain. The attenuation correction was based on an iterative projection/back-projection method. All studies were made on a three-headed SPET system (Trionix) with medium-energy parallel-hole collimators. The set of input data for quantification was based on SPET acquisition of emission data in four separate energy windows, the associated cumulative energy spectra and transmission data. The attenuation correction routine as well as the edge detection algorithm utilized data from (99m)Tc transmission tomography. Attenuation data for (113m)In were obtained by linear scaling of the (99m)Tc attenuation maps. The correction algorithms were experimentally validated with a stack phantom system and applied on a healthy volunteer. The mean difference between the corrected SPET data of the dense stack lung phantom and those obtained from the corresponding scatter- and attenuation-"free" version was only 1.9% for (99m)Tc and 0.9% for (113m)In. The estimated fractional V/Q distribution in the 3-D lung phantom volume had its peak at V/Q=1, with a width (FWHM) of 0.31 due to noise, particularly in the (113m)In images, and to partial volume effects. For a healthy volunteer, the corresponding values were 0.9 and 0.35, respectively. This method allows accurate assessment of radionuclide distribution on a regional basis. For basic lung physiology and clinical practice, the method allows assessment of the global frequency functions of the V, Q and V/Q distributions. PMID:12111126

Sánchez-Crespo, Alejandro; Petersson, Johan; Nyren, Sven; Mure, Margareta; Glenny, Robb W; Thorell, Jan-Olov; Jacobsson, Hans; Lindahl, Sten G E; Larsson, Stig A

2002-07-01

21

Mixed Acid-Base Disorders, Hydroelectrolyte Imbalance and Lactate Production in Hypercapnic Respiratory Failure: The Role of Noninvasive Ventilation  

PubMed Central

Background Hypercapnic Chronic Obstructive Pulmonary Disease (COPD) exacerbation in patients with comorbidities and multidrug therapy is complicated by mixed acid-base, hydro-electrolyte and lactate disorders. Aim of this study was to determine the relationships of these disorders with the requirement for and duration of noninvasive ventilation (NIV) when treating hypercapnic respiratory failure. Methods Sixty-seven consecutive patients who were hospitalized for hypercapnic COPD exacerbation had their clinical condition, respiratory function, blood chemistry, arterial blood gases, blood lactate and volemic state assessed. Heart and respiratory rates, pH, PaO2 and PaCO2 and blood lactate were checked at the 1st, 2nd, 6th and 24th hours after starting NIV. Results Nine patients were transferred to the intensive care unit. NIV was performed in 11/17 (64.7%) mixed respiratory acidosis–metabolic alkalosis, 10/36 (27.8%) respiratory acidosis and 3/5 (60%) mixed respiratory-metabolic acidosis patients (p?=?0.026), with durations of 45.1±9.8, 36.2±8.9 and 53.3±4.1 hours, respectively (p?=?0.016). The duration of ventilation was associated with higher blood lactate (p<0.001), lower pH (p?=?0.016), lower serum sodium (p?=?0.014) and lower chloride (p?=?0.038). Hyponatremia without hypervolemic hypochloremia occurred in 11 respiratory acidosis patients. Hypovolemic hyponatremia with hypochloremia and hypokalemia occurred in 10 mixed respiratory acidosis–metabolic alkalosis patients, and euvolemic hypochloremia occurred in the other 7 patients with this mixed acid-base disorder. Conclusions Mixed acid-base and lactate disorders during hypercapnic COPD exacerbations predict the need for and longer duration of NIV. The combination of mixed acid-base disorders and hydro-electrolyte disturbances should be further investigated. PMID:22539963

Terzano, Claudio; Di Stefano, Fabio; Conti, Vittoria; Di Nicola, Marta; Paone, Gregorino; Petroianni, Angelo; Ricci, Alberto

2012-01-01

22

Increase in Pulmonary Ventilation-Perfusion Inequality with Age in Healthy Individuals  

Microsoft Academic Search

Arterial oxygen tension (Pa O 2 ) is known to decrease with age, and this is accompanied by a number of changes in mechanical properties of the lungs, including loss of elastic recoil and increase in clos- ing volume. The changes in respiratory mechanics with age could induce greater ventilation\\/perfu- sion ( ) mismatch and thus explain the decrease in

JAUME CARDÚS; FELIP BURGOS; ORLANDO DIAZ; JOSEP ROCA; JOAN ALBERT BARBERÀ; RAMÓN M. MARRADES; ROBERT RODRIGUEZ-ROISIN; PETER D. WAGNER

1997-01-01

23

Lung ventilation- and perfusion-weighted Fourier decomposition magnetic resonance imaging: in vivo validation with hyperpolarized 3He and dynamic contrast-enhanced MRI.  

PubMed

The purpose of this work was to validate ventilation-weighted (VW) and perfusion-weighted (QW) Fourier decomposition (FD) magnetic resonance imaging (MRI) with hyperpolarized (3)He MRI and dynamic contrast-enhanced perfusion (DCE) MRI in a controlled animal experiment. Three healthy pigs were studied on 1.5-T MR scanner. For FD MRI, the VW and QW images were obtained by postprocessing of time-resolved lung image sets. DCE acquisitions were performed immediately after contrast agent injection. (3)He MRI data were acquired following the administration of hyperpolarized helium and nitrogen mixture. After baseline MR scans, pulmonary embolism was artificially produced. FD MRI and DCE MRI perfusion measurements were repeated. Subsequently, atelectasis and air trapping were induced, which followed with FD MRI and (3)He MRI ventilation measurements. Distributions of signal intensities in healthy and pathologic lung tissue were compared by statistical analysis. Images acquired using FD, (3)He, and DCE MRI in all animals before the interventional procedure showed homogeneous ventilation and perfusion. Functional defects were detected by all MRI techniques at identical anatomical locations. Signal intensity in VW and QW images was significantly lower in pathological than in healthy lung parenchyma. The study has shown usefulness of FD MRI as an alternative, noninvasive, and easily implementable technique for the assessment of acute changes in lung function. PMID:22392633

Bauman, Grzegorz; Scholz, Alexander; Rivoire, Julien; Terekhov, Maxim; Friedrich, Janet; de Oliveira, Andre; Semmler, Wolfhard; Schreiber, Laura Maria; Puderbach, Michael

2013-01-01

24

Artificial perfusion of the ponto-medullary region of cats. A method for separation of central and peripheral effects of chemical stimulation of ventilation.  

PubMed

A technique is described by which the ponto-medullary region of anaesthetized cats is artificially perfused with their own blood in which the blood gas tensions are varied independently from gas exchange in the lung. Blood from a femoral artery is fed into a foamer and defoamer. After alteration of the blood gas tensions in this equilibrator it is pumped via a cannulated vertebral artery into the medulla oblongata, pons and cerebellum. In this way two separately perfused areas are obtained in which the blood gas tensions can be changed independently. The peripheral chemoreceptors are supplied with blood of the systemic circulation while the central chemoreceptors and respiratory integrating centres are artificially perfused. With this technique the contribution of the peripheral and central chemoreceptors to the total ventilation and their interaction can be assessed. In addition the method is also suitable for studying the effects of drugs on the central regulation of respiration and circulation. PMID:493755

Berkenbosch, A; Heeringa, J; Olievier, C N; Kruyt, E W

1979-08-01

25

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

26

The Bedside Investigation of Pulmonary Embolism Diagnosis Study A Double-blind Randomized Controlled Trial Comparing Combinations of 3 Bedside Tests vs Ventilation-Perfusion Scan for the Initial Investigation of Suspected Pulmonary Embolism  

Microsoft Academic Search

Background: We sought to determine whether using combinations of 3 bedside tests (7-variable clinical model, non-enzyme-linked immunosorbent assay D-dimer test, and alveolar dead-space fraction) to exclude pulmonary embolism (PE) before diagnostic imaging was as safe as a standard strategy of starting with ventilation- perfusion (V\\/Q) scan. Methods: In this double-blind, randomized, con- trolled equivalency trial, patients were randomized to ini-

Marc A. Rodger; Christopher N. Bredeson; Gwynne Jones; Pasteur Rasuli; Francois Raymond; Anne Marie Clement; Alan Karovitch; Helene Brunette; Dimitri Makropoulos; Mark Reardon; Ian Stiell; Rama Nair; Philip S. Wells

2006-01-01

27

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

28

An evaluation of preoperative and postoperative ventilation and perfusion lung scintigraphy in the screening for pulmonary embolism after elective orthopedic surgery  

SciTech Connect

One hundred two patients undergoing elective knee or hip arthroplasty were studied with radionuclide ventilation scans (V) and perfusion scans (Q) preoperatively (preop) and postoperatively (postop) to assess their relative value in the diagnosis of asymptomatic pulmonary embolism (PE) after orthopedic surgery. Postop Q were read in combination with preop V and Q and postop V using prospective investigation of pulmonary embolism diagnosis (PIOPED) criteria. Of 25 postop Q interpreted as either high or intermediate probability for PE, preop Q were judged useful in 96%; the postop V were useful in 78%; and the preop V were not helpful in any of the cases. Of 63 postop Q interpreted as low probability, preop Q were useful in 74%; the postop V were useful in only 33%; and the preop V were useful in only one case. When postop Q were read as normal (14 cases), none of the three auxiliary studies were found to be useful. Overall, postop V were more helpful than preop Q in only 2%, and preop V contributed significantly in only 1%. This experience suggests that preop Q alone is the most useful adjunct to the postop Q in the postoperative evaluation for PE. The authors conclude that to screen for asymptomatic PE after elective orthopedic surgery, preop Q should be performed in all cases, preop V are not necessary, and postop V need be performed only if a baseline preop Q is not available.

Keenan, A.M.; Palevsky, H.I.; Steinberg, M.E.; Hartman, K.M.; Alavi, A.; Lotke, P.A. (Univ. of Pennsylvania, Philadelphia (USA))

1991-01-01

29

N-terminal natriuretic peptide and ventilation-perfusion lung scan in sickle cell disease and thalassemia patients with pulmonary hypertension.  

PubMed

The aim of this study was to determine the prevalence of pulmonary hypertension (PH) in sickle cell disease and thalassemia patients in relation to clinical and laboratory parameters of hemolysis and hemosidersosis, as well as plasma N-terminal pro-brain natriuretic peptide (NT-pro-BNP). The study also aimed to define the role of thromboembolic pulmonary artery (PA) obstruction in its etiology. Forty sickle cell disease and 30 thalassemia patients [15 beta-thalassemia major (beta-TM) and 15 beta-thalassemia intermedia (beta-TI)] were screened for PH defined as tricuspid regurgitant velocity (TRV) >2.5 m/sec and evaluated for PA obstruction using ventilation-perfusion lung scan (V/Q), together with measurement of their plasma levels of NT-pro-BNP. Patients were prospectively followed up for a mean of 18 +/- 6.1 months. The prevalence of PH was 37.5, 40.0 and 26.7% in sickle cell disease, beta-TI and beta-TM patients, respectively. Pulmonary hypertension patients were older, had longer disease duration, higher serum ferritin, serum lactate dehydrogenase (LDH) and NT-pro-BNP with lower hemoglobin (Hb) levels compared to patients without PH. N-terminal pro-BNP was positively correlated with duration of illness, TRV, LDH, serum ferritin, and negatively correlated with Hb levels. The strongest predictor for TRV was serum ferritin followed by the NT-pro-BNP level. Forty-six-point-seven percent of sickle cell disease patients with PH had either high or intermediate probability V/Q scan results compared to 10% of thalassemic patients with PH who had high probability V/Q scan results. Pulmonary hypertension is highly prevalent in young sickle cell disease and thalassemia patients, where elevated serum ferritin and NT-pro-BNP are the main indicators. PMID:20113292

Mokhtar, Galila M; Adly, Amira A M; El Alfy, Mohsen S; Tawfik, Lamis M; Khairy, Ahmed T

2010-01-01

30

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

31

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

32

Muscle imbalance among elite athletes  

Microsoft Academic Search

BackgroundPrevious research in team sports, such as football and cricket, has found muscle imbalances in the lumbo-pelvic region, especially in muscles involved in joint stability and protection. It is thought that these muscle imbalances occur as a result of the specific requirements of the sport. However, this pattern of muscular imbalance may not be isolated to team sports and may

M Franettovich; J Hides; M D Mendis; H Littleworth

2011-01-01

33

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

34

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

35

Ventilative cooling  

E-print Network

This thesis evaluates the performance of daytime and nighttime passive ventilation cooling strategies for Beijing, Shanghai and Tokyo. A new simulation method for cross-ventilated wind driven airflow is presented . This ...

Graça, Guilherme Carrilho da, 1972-

1999-01-01

36

Repeat perfusion imaging may differentiate airways obstruction from pulomonary embolic disease: report of two cases  

SciTech Connect

Two cases are presented in which patients with obstructive lung disease were considered to have a pulmonary embolism (PE). Emergency lung perfusion scans supported the diagnosis of PE in both cases. However, rapid resolution of the symptoms and perfusion defects by repeat ventilation-perfusion scanning at 24 hr suggested that PE was unlikely. In selected cases of wheezing patients, repeat perfusion scans may obviate the need for pulmonary angiography. The authors report two cases in which repeat perfusion scans almost normalized by 24 hr. Review of the literature indicates that the rate of resolution of perfusion defects would have been much slower had pulmonary embolism occurred.

Greenspon, L.W.; LaManna, M.M.; Dhand, S.

1987-06-01

37

Simulation investigation of wind turbine imbalance faults  

Microsoft Academic Search

This paper investigates the use of simulations to study wind turbine imbalance faults. The dynamics of a model wind turbine generator (WTG) are simulated in a combined environment of TurbSim, FAST (Fatigue, Aerodynamics, Structures, Turbulence), and Simulink in three different scenarios, i.e., normal operating conditions, blade imbalance, and aerodynamic asymmetry. The blade imbalance is simulated by scaling the mass density

Xiang Gong; Wei Qiao

2010-01-01

38

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

39

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

40

Assessment of Changes in Distribution of Lung Perfusion by Electrical Impedance Tomography  

Microsoft Academic Search

Background: Electrical impedance tomography (EIT) is able to detect variations in regional lung electrical impedance associated with changes in both air and blood content and potentially capable of assessing regional ventilation-perfusion relationships. However, regional lung perfusion is difficult to determine because the impedance changes synchronous with the heart rate are of very small amplitude. Objectives: The aim of our study

Inéz Frerichs; Sven Pulletz; Gunnar Elke; Florian Reifferscheid; Dirk Schädler; Jens Scholz; Norbert Weiler

2009-01-01

41

Earth's Energy Imbalance and Implications  

NASA Astrophysics Data System (ADS)

Improving observations of ocean heat content show that Earth is absorbing more energy from the Sun than it is radiating to space as heat, even during the recent solar minimum. We update our analysis of Earth's observed energy imbalance through 2011 and compare this with climate simulations. Observed global surface temperature change and ocean heat gain together constrain the net climate forcing, implying existence of a large negative forcing by human-made aerosols. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We discuss implications of the trend of observed sea level rise in recent years, and its consistency with reported ice melt rates and ocean thermal expansion.

Hansen, J.; von Schuckmann, K.; Sato, M.; Kharecha, P.

2012-04-01

42

Sustained Pressure Perfusion Method.  

National Technical Information Service (NTIS)

A reliable and effective method of perfusing animal tissue in vivo under a constantly monitored pressure was described. The method was successfully used for perfusion of brain tissues of Cebus apella monkeys. Using the proper fixative, this method can be ...

L. J. Ackerman, R. S. Demaree, D. L. Anderson

1971-01-01

43

FATE OF INHALED NITROGEN DIOXIDE IN ISOLATED PERFUSED RAT LUNG  

EPA Science Inventory

The fate of inhaled NO2 was studied with isolated perfused rat lungs. The isolated lungs were exposed to 5 ppm NO2 for 90 min at a ventilation rate of 45 ml/min. The NO2 exposure had no adverse effects on the lungs as judged from their weights, glucose uptake, or lactate producti...

44

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.

45

Regional pulmonary perfusion following human heart-lung transplantation  

SciTech Connect

Ventilation and perfusion scans were obtained in six subjects who had undergone heart-lung transplantation with consequent denervation of the cardiopulmonary axis. Two of the subjects had developed obliterative bronchiolitis, which is believed to be a form of chronic rejection. Their pulmonary function tests demonstrated airflow obstruction and their scintigraphic studies were abnormal. In the remaining four subjects without obstructive airways disease, ventilation and planar perfusion scans were normal. Single photon emission computed tomography imaging of pulmonary perfusion in these patients revealed a layered distribution of blood flow indistinguishable from that of normal individuals. It is concluded that neurogenic mechanisms have little influence on the pattern of local pulmonary blood flow at rest.

Lisbona, R.; Hakim, T.S.; Dean, G.W.; Langleben, D.; Guerraty, A.; Levy, R.D. (Royal Victoria Hospital, Montreal, Quebec (Canada))

1989-08-01

46

The surface energy imbalance problem  

NASA Astrophysics Data System (ADS)

The 'energy imbalance problem' in micrometeorology arises because at most flux measurement sites the sum of eddy fluxes of sensible latent heat (H + ?E) is 50 - 200 W m-2 less than the available energy (A) at half-hourly time scales. Thus either eddy fluxes of H and ?Eare underestimated or A is overestimated. Lack of energy closure is caused by: 1) a failure to satisfy the fundamental assumption of one-dimensional transport needed for measurements on a single tower to represent spatially-averaged fluxes to/from the underlying surface; 2) measurement errors in: i) eddy fluxes, ii) net radiation, iii) changes in energy storage in soils, air, and biomass below the measurement height. Review of the literature shows that radiometric errors are unlikely to cause significant overestimates of A at all flux measurement sites, but phase lags between H + ?E and A caused by incorrect estimates of the energy storage terms that contribute to A can explain why H + ?E systematically underestimates A at half-hourly time scales. Energy closure is observed at only 8% of flux sites in the La Thuile dataset (http://www.fluxdata.org/DataInfo/default.aspx), with a median slope of 0.75 for H + ?E versus A for half-hourly averages. Using 24h averages leads to energy closure at 45% of the La Thuile sites, and the median slope of H + ?E versus A increases to 0.90. Increasing the averaging time reduces the bias in A because energy entering the soil, air and biomass in the morning is returned in the afternoon and evening. Unrealistically large positive horizontal temperature gradients of 4 - 10 °K km-1 are needed for horizontal advective flux divergences to explain the 50 - 200 W m-2 underestimate of H + ?E compared to A often observed at half-hourly time scales. Similarly, unrealistically large mean vertical velocities and temperature gradients are needed for vertical advective flux divergences to account for the 'missing' energy. Imbalances between H + ?E and A still occur in daily averages but the small residual energy imbalances are explicable by positive and negative horizontal and vertical advective flux divergences. Systematic underestimates of the vertical heat flux also occur if horizontal u'T'covariances contaminate the vertical w'T' signal due to incorrect coordinate rotations. An incorrect tilt angle of 2° will cause a 5% underestimate of H. Closure of the energy balance is possible at half-hourly time scales by careful selection of horizontally homogeneous sites to satisfy the assumptions of one-dimensional transport underpinning eddy covariance measurements on single towers , attention to all sources of measurement and data processing errors in the eddy covariance system, and by accurate measurement of net radiation and every energy storage term needed to calculate available energy.

Leuning, R.; van Gorsel, E.; Massman, W.

2012-04-01

47

Earth's energy imbalance and implications  

NASA Astrophysics Data System (ADS)

Improving observations of ocean heat content show that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.59 ± 0.15 W m-2 during the 6-year period 2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be -1.6 ± 0.3 W m-2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade. Humanity is potentially vulnerable to global temperature change, as discussed in the Intergovernmental Panel on Climate Change (IPCC, 2001, 2007) reports and by innumerable authors. Although climate change is driven by many climate forcing agents and the climate system also exhibits unforced (chaotic) variability, it is now widely agreed that the strong global warming trend of recent decades is caused predominantly by human-made changes of atmospheric composition (IPCC, 2007). The basic physics underlying this global warming, the greenhouse effect, is simple. An increase of gases such as CO2 makes the atmosphere more opaque at infrared wavelengths. This added opacity causes the planet's heat radiation to space to arise from higher, colder levels in the atmosphere, thus reducing emission of heat energy to space. The temporary imbalance between the energy absorbed from the sun and heat emission to space, causes the planet to warm until planetary energy balance is restored. The planetary energy imbalance caused by a change of atmospheric composition defines a climate forcing. Climate sensitivity, the eventual global temperature change per unit forcing, is known with good accuracy from Earth's paleoclimate history. However, two fundamental uncertainties limit our ability to predict global temperature change on decadal time scales. First, although climate forcing by human-made greenhouse gases (GHGs) is known accurately, climate forcing caused by changing human-made aerosols is practically unmeasured. Aerosols are fine particles suspended in the air, such as dust, sulfates, and black soot (Ramanathan et al., 2001). Aerosol climate forcing is complex, because aerosols both reflect solar radiation to space (a cooling effect) and absorb solar radiation (a warming effect). In addition, atmospheric aerosols can alter cloud cover and cloud properties. Therefore, precise composition-specific measurements of aerosols and their effects on clouds are needed to assess the aerosol role in climate change. Second, the rate at which Earth's surface temperature approaches a new equilibrium in response to a climate forcing depends on how efficiently heat perturbations are mixed into the deeper ocean. Ocean mixing is complex and not necessarily simulated well by climate models. Empirical data on ocean heat uptake are improving rapidly, but still suffer limitations. We summarize current understanding of this basic physics of global warming and note observations needed to narrow uncertainties. Appropriate measurements can quantify the major factors driving climate change, reveal how much additional global warming is already in the pipeline, and help define the reduction of climate forcing needed to stabilize climate.

Hansen, J.; Sato, M.; Kharecha, P.; von Schuckmann, K.

2011-09-01

48

Earth's Energy Imbalance and Implications  

E-print Network

Abstract. Improving observations of ocean heat content show that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.59 ± 0.15 W/m 2 during the 6-year period 2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be ?1.6 ± 0.3 W/m 2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade.

James Hansen; Makiko Sato; Pushker Kharecha

49

Earth's energy imbalance and implications  

NASA Astrophysics Data System (ADS)

Improving observations of ocean heat content show that Earth is absorbing more energy from the Sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.58 ± 0.15 W m-2 during the 6-yr period 2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be -1.6 ± 0.3 W m-2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade.

Hansen, J.; Sato, M.; Kharecha, P.; von Schuckmann, K.

2011-12-01

50

Meeting Residential Ventilation Standards  

E-print Network

LBNL 4591E Meeting Residential Ventilation Standards Through Dynamic Control of Ventilation Systems Orlando Lawrence Berkeley National Laboratory is an equal opportunity employer. #12;ABSTRACT Existing of whole-house ventilation systems to meet the intent of ventilation standards and demonstrates the dynamic

51

VENTILATION NEEDS DURING CONSTRUCTION  

SciTech Connect

The purpose of this analysis is to determine ventilation needs during construction and development of the subsurface repository and develop systems to satisfy those needs. For this analysis, construction is defined as pre-emplacement excavation and development is excavation that takes place simultaneously with emplacement. The three options presented in the ''Overall Development and Emplacement Ventilation Systems'' analysis (Reference 5.5) for development ventilation will be applied to construction ventilation in this analysis as well as adding new and updated ventilation factors to each option for both construction and development. The objective of this analysis is to develop a preferred ventilation system to support License Application Design. The scope of this analysis includes: (1) Description of ventilation conditions; (2) Ventilation factors (fire hazards, dust control, construction logistics, and monitoring and control systems); (3) Local ventilation alternatives; (4) Global ventilation options; and (5) Evaluation of options.

C.R. Gorrell

1998-07-23

52

Governmental-Owner Power Imbalance and Privatization  

E-print Network

relationships of SOEs and their governmental owners. Four panel databases of 206 pharmaceutical firms across eight years in China were combined to answer the research question of this dissertation: What is the role of power imbalance between different...

Xu, Kehan

2011-10-21

53

Redox imbalance and biochemical changes in cancer.  

PubMed

For this article, we explore a hypothesis involving the possible role of reduction/oxidation (redox) state in cancer. We hypothesize that many modifications in cellular macromolecules, observed in cancer progression, may be caused by redox imbalance. Recent biochemical data suggest that human prostate cancer cell lines show a redox imbalance (oxidizing) compared with benign primary prostate epithelial cells; the degree of oxidation varied with aggressive behavior of each cell line. Our recent data suggest that human breast cancer tissues show a redox imbalance (reducing) compared with benign adjacent breast tissues. Accumulating data summarized in this article suggest that redox imbalance may regulate gene expression and alter protein stability by posttranslational modifications, in turn modulating existing cellular programs. Despite significant improvements in cancer therapeutics, resistance occurs, and redox imbalance may play a role in this process. Studies show that some cancer therapeutic agents increase generation of reactive oxygen/nitrogen species and antioxidant enzymes, which may alter total antioxidant capacity, cause cellular adaptation, and result in reduced effectiveness of treatment modalities. Approaches involving modulations of intra- and extracellular redox states, in combination with other therapies, may lead to new treatment options, especially for patients who are resistant to standard treatments. PMID:23878188

Jorgenson, Tonia C; Zhong, Weixiong; Oberley, Terry D

2013-10-15

54

JAMA Patient Page: Mechanical Ventilation  

MedlinePLUS

... of the American Medical Association JAMA PATIENT PAGE Mechanical Ventilation T he support of respiration (breathing) with devices is known as mechanical ventilation . Mechanical ventilation, provided by ventilators , is used ...

55

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

56

VENTILATION TECHNOLOGY SYSTEMS ANALYSIS  

EPA Science Inventory

The report gives results of a project to develop a systems analysis of ventilation technology and provide a state-of-the-art assessment of ventilation and indoor air quality (IAQ) research needs. (NOTE: Ventilation technology is defined as the hardware necessary to bring outdoor ...

57

Sympathovagal Imbalance in Patients with Vasovagal Syncope  

Microsoft Academic Search

Background: Vasovagal syncope (VVS) is one of the most frequent causes of unexplained syncope and can be assessed by a Tilt Table Test (TTT). The pathophysiology of VVS is related to an imbalance of the autonomic nervous system (ANS). The aim of this study was to compare the autonomic status by Heart Rate Variability (HRV) during asymptomatic periods in patients

Monsawan Miniphan; Rungroj Krittayaphong

2009-01-01

58

Patient-ventilator asynchrony during assisted mechanical ventilation  

Microsoft Academic Search

Objective  The incidence, pathophysiology, and consequences of patient-ventilator asynchrony are poorly known. We assessed the incidence of patient-ventilator asynchrony during assisted mechanical ventilation and we identified associated factors.Methods  Sixty-two consecutive patients requiring mechanical ventilation for more than 24?h were included prospectively as soon as they triggered all ventilator breaths: assist-control ventilation (ACV) in 11 and pressure-support ventilation (PSV) in 51.Measurements  Gross asynchrony detected

Arnaud W. Thille; Pablo Rodriguez; Belen Cabello; François Lellouche; Laurent Brochard

2006-01-01

59

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

60

Education in the imbalance of Nature  

NASA Astrophysics Data System (ADS)

There are two concepts understanding of the real Nature: balanced and imbalanced. The traditional balanced concept understanding of Nature was originated in prehistoric times to calm the frightened souls of prehistoric man and manage groups of people. The balanced concept presupposes that Nature is isotropic, balanced, etc. The balanced concept of understanding of Nature gradually has moved to science and technology. The balanced concept of understanding of Nature is dominating from the prehistoric time up to today. But always parallel and opposite was exists the concept imbalanced understanding of Nature, which presupposes that Nature is anisotropy, imbalanced, etc. The balanced concept is much simpler than Imbalanced. The balanced concept has given mankind a lot of rough description of Nature which helped to solve a lot of practical problems but with sufficient accuracy, i.e. approximately, but not with an absolute precision. While people were few, and a lot of resources, person could take from Nature only what Nature gave willingly. During this period, people feared and respected Nature and Nature was able easily compensate the activity of people. The high accuracy of the description of Nature was not needed when resources were plentiful and people were few. But now the situation is completely different. The population has become a very large and growing. Traditional resources are almost run out and the lack of resources escalates. People are not afraid of Nature and bravely try to take by force what Nature does not give voluntarily. People invaded into imbalance Nature, and Nature can no longer compensate activity of people. The era of global change is started, including those that man provokes. In the conditions of global changes is insufficiently of the approximate solutions of the traditional balanced concept. The balanced concept is exhausted, and increasingly misleads people. The balanced concept cannot solve the problems that arise in the global change. The Concept imbalance of Nature is more suitable to solve problems of global change. Many thousands of scientists and practical from around the world are working already in the field of imbalance of Nature. Now is a time when the concept imbalance of Nature should be included into the training programs at universities, colleges and schools. We have experts who can teach students in imbalance of Nature. We have a list of topics for Ph.D. dissertations in field of imbalance of Nature. Now we are preparing the fundamental scientific book on all major issues imbalance of Nature. On the basis of this fundamental scientific work will be prepared the textbooks for students of different levels, non-fiction books, will organized promotion of the imbalance of Nature in the media, social networks, etc. People need to understand the real Nature as it is. This new knowledge will help humanity make the right and safer decisions in the era of global change. We invite the universities, colleges, schools, community organizations, sponsors and just responsible people of any country in the world to take part in this noble and vital issue. Humanity has no choice. Or mankind will have time to learn how to live in the era of global change or perish. The concept imbalance of Nature gives humanity the chance to survive.

Shlafman, L. M.; Kontar, V. A.

2013-12-01

61

Order imbalance and stock returns: Evidence from China  

E-print Network

We investigate the relation between daily order imbalance and return in the Chinese stock markets of Shenzhen and Shanghai. Prior studies have found that daily order imbalance is predictive of subsequent returns. On the ...

Shenoy, Catherine

2007-01-01

62

Lung scan perfusion defects limited to matching pleural effusions: low probability of pulmonary embolism  

SciTech Connect

Patients with a new pleural effusion are often sent for a ventilation-perfusion scan to exclude a pulmonary embolism. This retrospective study assessed the probability of pulmonary embolism when a pleural effusion and a perfusion defect of similar size are the only significant imaging abnormalities. In 451 reports of patients who were scanned for suspected pulmonary embolism, 53 had perfusion defects secondary to pleural effusion without other significant perfusion defects. Using pulmonary angiography, venography, analysis of pleural fluid, clinical course, and other radiographic and laboratory studies to establish the final diagnosis, only two patients had documented venous thrombotic disease: one had pulmonary emboli, the other thrombophlebitis. Lung scans having significant perfusion defects limited to pleural effusions and matching them in size have a low probability for pulmonary embolism.

Bedont, R.A.; Datz, F.L.

1985-12-01

63

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 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. Revision 01 ICN 01 included the results of the unqualified software code MULTIFLUX to assess the influence of moisture on the ventilation efficiency. The purposes of Revision 02 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 asses the impacts of moisture on the ventilation efficiency.

V. Chipman; J. Case

2002-12-20

64

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

65

Earth's Energy Imbalance and Ocean Heat Storage  

NASA Astrophysics Data System (ADS)

The Earth's energy imbalance, i.e., the difference between solar energy absorbed and thermal energy emitted by the planet, is fundamental to global climate change, as it measures the net forcing acting on the climate system. The imbalance is now positive on decadal time scales, due to dominance of increasing greenhouse gas (GHG) forcing, and, with canonical climate sensitivity, it yields an estimate of the amount of global warming that remains "in the pipeline" due to GHGs already in the atmosphere. The ocean is the largest sink for excess incoming energy. Inference of information from the energy imbalance is affected by a trade-off between decreasing accuracy of earlier data and the added information from longer time scales. We use two atmosphere-ocean models, with ocean heat and sea level measurements, to study the roles of different climate forcings, unforced climate variability including ocean- cloud interactions, and limitations of data sampling. We find that observed decrease in ocean heat content in the upper 750m in 2004-2005 does not significantly alter the estimate of ~0.5C global warming still "in the pipeline". Continuation and refinement of measurements of ocean heat, sea level, and ice sheet mass balance have the potential to greatly refine understanding of global warming, its practical implications, and important climate processes, but to be most useful they need to be supplemented by better measurements of deep ocean heat content changes and precise measurements of changing climate forcings such as tropospheric aerosols.

Hansen, J.; Willis, J.; Leuliette, E.; Bleck, R.; Lo, K.; Ruedy, R.; Sato, M.; Sun, S.

2006-12-01

66

Collateral ventilation and gas exchange in emphysema.  

PubMed

Resistance to collateral flow of gas is high in the normal human lung but may be lower in emphysema. However, the contribution of collateral ventilation to gas exchange in emphysema remains unclear. This study evaluates the role and magnitude of collateral ventilation between bronchopulmonary segments in six patients with clinical, functional, and computed tomographic evidence of emphysema, compared with our previous findings in 12 normal subjects. To assess collateral flow, a balloon-tipped catheter with a lumen that opened distal to the balloon was inflated in segmental bronchi during fiberoptic bronchoscopy. Respiratory gas tensions were sampled by mass spectrometer from beyond the occlusion via the catheter lumen. Subjects breathed air until occlusion was established and then switched to 79% helium/21% oxygen. The rate of rise of helium concentration was measured within occluded segments and used as an index of collateral ventilation. The mean (+/- SEM) rate of rise of helium concentration was ten times greater in emphysema patients (9.5 +/- 2.7%/min) compared with normal subjects (0.8 +/- 0.3%/min) (p = 0.009). The mean PO2 within occluded segments was similar in normal subjects and emphysema patients: 45.4 +/- 1.8 mm Hg and 44.8 +/- 3.6 mm Hg, respectively. Mean PCO2 within occluded segments was lower in patients (40.1 +/- 1.9 mm Hg) than in normal subjects (46.4 +/- 1.3 mm Hg), probably due to higher regional ventilation-perfusion ratios in emphysema patients rather than collateral ventilation. In emphysema patients there was a positive correlation between rate of rise of helium concentration and final PO2 within an occluded segment (r = 0.73; p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8087331

Morrell, N W; Wignall, B K; Biggs, T; Seed, W A

1994-09-01

67

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

68

Contaminants in Naturally Ventilated  

E-print Network

a natural ventilation/flushing Volcanic Magma Chambers Deep Ocean Recirculation Basins Lakes Buildings (My? Passive (Gaseous) Particulate Radon Paint Fumes Gas Odours CO2 This is a very short, very incomplete list;Displacement Ventilation An air distribution system in which incoming air originates at floor level and rises

Politècnica de Catalunya, Universitat

69

Multifamily Ventilation Retrofit Strategies  

SciTech Connect

In multifamily buildings, central ventilation systems often have poor performance, overventilating some portions of the building (causing excess energy use), while simultaneously underventilating other portions (causing diminished indoor air quality). BSC and Innova Services Corporation performed a series of field tests at a mid-rise test building undergoing a major energy audit and retrofit, which included ventilation system upgrades.

Ueno, K.; Lstiburek, J.; Bergey, D.

2012-12-01

70

[Human resources and their mitigatable imbalances].  

PubMed

In this paper, the policy-sensitive imbalances in the health professional markets are discussed. In Spain, the current staffing levels are still the result of unforeseen demographic and socio-economic developments. In some specialties and areas, there are selective shortages which in all likelihood will become more serious in the coming years due to the objective causes analyzed in this text. We propose a gradual increase in the medical schools numerus clausus and in the number of residents positions, the use of a variety of incentives to attract professionals to specific positions and, particularly, to increase the standing and quality of primary care. PMID:16539972

González López-Valcárcel, Beatriz; Barber-Pérez, Patricia

2006-03-01

71

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

72

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

73

[High frequency jet ventilation].  

PubMed

High frequency jet ventilation (HFJV) is a new ventilation technique which ensures satisfactory gas exchanges with tidal volumes of about 2 ml . kg-1. A gas mixture under high pressure is "chopped up" by an electrically-controlled solenoid valve and delivered to the patient by an injection system. A specific heater-humidifier is required for optimal humidity and warmth of the gas mixture. HFJV creates a positive end-expiratory pressure effect in the alveoles, and the increase of mean intratracheal pressure observed accurately reflects the increase of mean alveolar pressure. Convection by direct alveolar ventilation plays a determinant role in CO2 clearance under HFJV, the other gas transport mechanisms being accessory. In respiratory failure with shock HFJV is better tolerated haemodynamically than conventional ventilation. The main indications of the new technique are ENT surgery, thoracic and tracheal surgery, lithotripsy, broncho-pleural and oesophago-tracheal fistulae and circulatory shock. PMID:2958820

Rouby, J J; Viars, P

1987-09-26

74

Ventilation Air Preconditioning Systems  

E-print Network

dedicated to preconditioning the outside air. This paper discusses two such systems for cooling and dehumidification applications: one with a separate preconditioning unit and one with separate ventilation and return air paths in a single unit. Both deep...

Khattar, M.; Brandemuehl, M. J.

1996-01-01

75

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

76

Conventional mechanical ventilation  

PubMed Central

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.

2010-01-01

77

Earth's Energy Imbalance: Confirmation and Implications  

NASA Astrophysics Data System (ADS)

Our climate model, driven mainly by increasing human-made greenhouse gases and aerosols, among other forcings, calculates that Earth is now absorbing 0.85 +/- 0.15 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years. Implications include (i) the expectation of additional global warming of about 0.6°C without further change of atmospheric composition; (ii) the confirmation of the climate system's lag in responding to forcings, implying the need for anticipatory actions to avoid any specified level of climate change; and (iii) the likelihood of acceleration of ice sheet disintegration and sea level rise.

Hansen, James; Nazarenko, Larissa; Ruedy, Reto; Sato, Makiko; Willis, Josh; Del Genio, Anthony; Koch, Dorothy; Lacis, Andrew; Lo, Ken; Menon, Surabi; Novakov, Tica; Perlwitz, Judith; Russell, Gary; Schmidt, Gavin A.; Tausnev, Nicholas

2005-06-01

78

Hindlimb unloading elicits anhedonia and sympathovagal imbalance  

PubMed Central

The hindlimb-unloaded (HU) rat model elicits cardiovascular deconditioning and simulates the physiological adaptations to microgravity or prolonged bed rest in humans. Although psychological deficits have been documented following bed rest and spaceflight in humans, few studies have explored the psychological effects of cardiovascular deconditioning in animal models. Given the bidirectional link established between cardiac autonomic imbalance and psychological depression in both humans and in animal models, we hypothesized that hindlimb unloading would elicit an alteration in sympathovagal tone and behavioral indexes of psychological depression. Male, Sprague-Dawley rats confined to 14 days of HU displayed anhedonia (a core feature of human depression) compared with casted control (CC) animals evidenced by reduced sucrose preference (CC: 81 ± 2.9% baseline vs. HU: 58 ± 4.5% baseline) and reduced (rightward shift) operant responding for rewarding electrical brain stimulation (CC: 4.4 ± 0.3 ?A vs. 7.3 ± 1.0 ?A). Cardiac autonomic blockade revealed elevated sympathetic [CC: ?54 ± 14.1 change in (?) beats/min vs. HU: ?118 ± 7.6 ? beats/min] and reduced parasympathetic (CC: 45 ± 11.8 ? beats/min vs. HU: 8 ± 7.3 ? beats/min) cardiac tone in HU rats. Heart rate variability was reduced (CC: 10 ± 1.4 ms vs. HU: 7 ± 0.7 ms), and spectral analysis of blood pressure indicated loss of total, low-, and high-frequency power, consistent with attenuated baroreflex function. These data indicate that cardiovascular deconditioning results in sympathovagal imbalance and behavioral signs consistent with psychological depression. These findings further elucidate the pathophysiological link between cardiovascular diseases and affective disorders. PMID:18635876

Moffitt, Julia A.; Grippo, Angela J.; Beltz, Terry G.; Johnson, Alan Kim

2008-01-01

79

Exercise training attenuates placental ischemia induced hypertension and angiogenic imbalance in the rat  

PubMed Central

An imbalance between pro-angiogenic (vascular endothelial growth factor, VEGF) and anti-angiogenic (soluble fms-like tyrosine kinase-1, sFlt-1) factors plays an important role in hypertension associated with reduced utero-placental perfusion (RUPP). Exercise has been shown to stimulate pro-angiogenic factors such as VEGF in both the pregnant and non-pregnant state, thus we hypothesized exercise training would attenuate both angiogenic imbalance and hypertension due to RUPP. Four groups of animals were studied: RUPP and normal pregnant (NP) controls and NP and RUPP + exercise training (NP or RUPP+EX). Exercise training attenuated RUPP-induced: hypertension (P<0.05); increased sFlt-1(P<0.05); decreased VEGF (P<0.05), and elevated sFlt-1:VEGF ratio. The positive effects of exercise on angiogenic balance in the RUPP rats were confirmed by restoration (P<0.05) of the RUPP-induced decrease in endothelial tube formation in HUVECs treated with serum from each of the experimental groups. Placental prolyl hydroxylase-1 (PHD1) was increased (P<0.05) in RUPP+Ex rats. Decreased trolox equivalent antioxidant capacity in the placenta, amniotic fluid and kidney of the RUPP rats was reversed by exercise. RUPP induced increase in renal TBARS was attenuated by exercise. The present data show exercise training before and during pregnancy attenuates placental ischemia-induced hypertension, angiogenic imbalance and oxidative stress in the RUPP rat and reveals that increased PHD1 is associated with decreased sFlt-1 thus revealing several potential pathways for exercise training to mitigate the effects of placental ischemia-induced hypertension. Lastly, the present study demonstrates exercise training may be a useful approach to attenuate the development of placental ischemia-induced hypertension during pregnancy. PMID:23090773

Gilbert, Jeffrey S; Banek, Christopher T; Bauer, Ashley J; Gingery, Anne; Needham, Karen

2013-01-01

80

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

81

THE ROLE OF IONORGANIC ION IMBALANCE IN AQUATIC TOXICITY TESTING  

EPA Science Inventory

This paper assessess the issue of ion imbalance, provides summary of applicable data, presents several successful technical tools to address toxicity resulting from salinity and ion imbalances, and discusses regulatory/compliance options to manage discharges with salinity/ion imb...

82

Determination of Functional Strength Imbalance of the Lower Extremities  

Microsoft Academic Search

The purposes of this study were (a) to determine whether a significant strength imbalance existed between the left and right or dominant (D) and nondominant (ND) legs and (b) to investigate possible correlations among various unilateral and bilateral closed kinetic chain tests, including a field test, and traditional isokinetic dynamometry used to determine strength imbalance. Fourteen Division I collegiate women

Robert U. Newton; Aimee Gerber; Sophia Nimphius; Jae K. Shim; Brandon K. Doan; Mike Robertson; David R. Pearson; Bruce W. Craig; Keijo Hakkinen; William J. Kraemer

2006-01-01

83

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

84

High-frequency ventilation of ducks and geese.  

PubMed

We studied gas exchange in anesthetized ducks and geese artificially ventilated at normal tidal volumes (VT) and respiratory frequencies (fR) with a Harvard respirator (control ventilation, CV) or at low VT-high fR using an oscillating pump across a bias flow with mean airway opening pressure regulated at 0 cmH2O (high-frequency ventilation, HFV). VT was normalized to anatomic plus instrument dead space (VT/VD) for analysis. Arterial PCO2 was maintained at or below CV levels by HFV with VT/VD less than 0.5 and fR = 9 and 12 s-1 but not at fR = 6 s-1. For 0.4 less than or equal to VT/VD less than or equal to 0.85 and 3 s-1. less than or equal to fR less than or equal to 12 s-1, increased VT/VD was twice as effective as increased fR at decreasing arterial PCO2, consistent with oscillatory dispersion in a branching network being an important gas transport mechanism in birds on HFV. Ventilation of proximal exchange units with fresh gas due to laminar flow is not the necessary mechanism supporting gas exchange in HFV, since exchange could be maintained with VT/VD less than 0.5. Interclavicular and posterior thoracic air sac ventilation measured by helium washout did not change as much as expired minute ventilation during HFV. PCO2 was equal in both air sacs during HFV. These results could be explained by alterations in aerodynamic valving and flow patterns with HFV. Ventilation-perfusion distributions measured by the multiple inert gas elimination technique show increased inhomogeneity with HFV. Elimination of soluble gases was also enhanced in HFV as reported for mammals.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3114225

Hastings, R H; Powell, F L

1987-07-01

85

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

86

Ventilation technologies scoping study  

SciTech Connect

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 needs of California, determining 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 level 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).

Walker, Iain S.; Sherman, Max H.

2003-09-30

87

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

88

Bench performance of ventilators during simulated paediatric ventilation.  

PubMed

This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2. PMID:23659397

Park, M A J; Freebairn, R C; Gomersall, C D

2013-05-01

89

Meeting Residential Ventilation Standards Through Dynamic Control of Ventilation Systems  

SciTech Connect

Existing 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 minimum ventilation, with time-based intermittent operation as an option. This requirement ignores several factors and concerns including: other equipment such as household exhaust fans that might incidentally provide ventilation, negative impacts of ventilation when outdoor pollutant levels are high, the importance of minimizing energy use particularly during times of peak electricity demand, and how the energy used to condition air as part of ventilation system operation changes with outdoor conditions. Dynamic control of ventilation systems can provide ventilation equivalent to or better than what is required by standards while minimizing energy costs and can also add value by shifting load during peak times and reducing intake of outdoor air contaminants. This article describes the logic that enables dynamic control of whole-house ventilation systems to meet the intent of ventilation standards and demonstrates the dynamic ventilation system control concept through simulations and field tests of the Residential Integrated Ventilation-Energy Controller (RIVEC).

Sherman, Max H.; Walker, Iain S.

2011-04-01

90

Immunological hazards from nutritional imbalance in athletes.  

PubMed

This review examines the influences of nutritional imbalance on immune function of competitive athletes, who may adopt an unusual diet in an attempt to enhance performance. A major increase in body fat can have adverse effects on immune response. In contrast, a negative energy balance and reduction of body mass are likely to impair immune function in an already thin athlete. A moderate increase in polyunsaturated fat enhances immune function, but excessive consumption can be detrimental. Since endurance exercise leads to protein catabolism, an athlete may need 2.0 g/kg protein rather than the 0.7-1.0 g/kg recommended for a sedentary individual. Both sustained exercise and overtraining reduce plasma glutamine levels, which may contribute to suppressed immune function postexercise. A large intake of carbohydrate counters glutamine depletion but may also modify immune responses by altering the secretion of glucose-regulating hormones. Vitamins are important to immune function because of their antioxidant role. However, the clinical benefits of vitamin C supplementation are not enhanced by the use of more complex vitamin mixtures, and excessive vitamin E can have negative effects. Iron, selenium, zinc, calcium, and magnesium ion all influence immune function. Supplements may be required after heavy sweating, but an excessive intake of iron facilitates bacterial growth. In making dietary recommendations to athletes, it is important to recognize that immune response can be jeopardized not only by deficiencies but also by excessive intake of certain nutrients. The goal should be a well-balanced diet. PMID:9644093

Shephard, R J; Shek, P N

1998-01-01

91

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

92

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

93

Literature Review of Displacement Ventilation  

E-print Network

of Ventilated Rooms, Oslo, Norway. Nielsen, P.V., Hoff, L., Pedersen, L.G. 1988. Displacement Ventilation by Different Types of Diffusers. Proceedings of the 9 th AIVC Conference, Warwick. Niu, J. 1994. Modeling of Cooled-Ceiling Air-Conditioning Systems Ph... slender cylinder in a ventilated room. Proceedings of ROOMVENT ?90: International Conference on Engineergin Aero- and Thermodynamics of Ventilated Rooms, Oslo, Norway. This paper deals with some of the effects of persons present in a displacement...

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

94

[Non-invasive ventilation].  

PubMed

The advent of non-invasive mechanical ventilation (NIMV) has radically changed the management of acute and chronic respiratory failure. Over the last few years, the number of possible applications of NIMV has progressively increased, both in the hospital and extrahospital setting. NIMV is now used in all hospitals and resident physicians currently receive specific training -nonexistent until a few years ago- in this modality. It falls to all of us to push forward the clinical and scientific advances represented by the development of NIMV, by promoting the events that accompany better knowledge of the physiopathological bases of ventilation and of its continuous applications in daily clinical practice and by perfecting the elements required for the correct application of this technique. The present review aims to provide a broad overview of NIMV, from the most theoretical knowledge (the physiopathology of NIMV) to the most practical skills (recognition of patient-ventilator asynchrony). Through this progression from the complex to the most basic, or from the basics to the most complex, depending on the perspective taken, we aim to provide deeper knowledge of the concepts required to understand the technical functioning of the ventilator, describing its distinct modes and parameters and the abilities that must be developed for the correct indication, use and monitoring of the technique. We provide a final reflection on other forms of respiratory support that can be offered to patients with ventilatory failure. PMID:21316544

Gallardo Romero, Jose Manuel; García, Teresa Gómez; Sancho Chust, José Norberto; González Martínez, Mónica

2010-10-01

95

Laboratory Ventilation and Safety.  

ERIC Educational Resources Information Center

In order to meet the needs of both safety and economy, laboratory ventilation systems must effectively remove air-borne toxic and flammable materials and at the same time exhaust a minimum volume of air. Laboratory hoods are the most commonly used means of removing gases, dusts, mists, vapors, and fumed from laboratory operations. To be effective,…

Steere, Norman V.

1965-01-01

96

Measure Guideline: Ventilation Cooling  

SciTech Connect

The purpose of this measure guideline on ventilation cooling is to provide information on a cost-effective solution for reducing cooling system energy and demand in homes located in hot-dry and cold-dry climates. This guideline provides a prescriptive approach that outlines qualification criteria, selection considerations, and design and installation procedures.

Springer, D.; Dakin, B.; German, A.

2012-04-01

97

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 ...

98

Heating and ventilation system  

Microsoft Academic Search

A system is described for controlling the temperature, ventilation, illumination, and humidity within an enclosed building having at least one wall exposed to solar radiation comprising: a double glazed window mounted on the wall; means for measuring the net heat energy flow through the window; means for automatically adjusting the heat energy flow; means provided for absorbing at least a

1974-01-01

99

Optimizing ventilation in conjunction with phased chest and abdominal compression-decompression (Lifestick) resuscitation.  

PubMed

The best method for employment of phased chest and abdominal compression-decompression (Lifestick) cardiopulmonary resuscitation (CPR) has yet to be determined. Of particular concern with using this technique is the combining of ventilation with the phased compressions and decompressions. Twenty domestic swine (50+/-1 kg) were equally divided into four groups. Following 10 min of untreated VF, CPR was begun. Group 1 received Lifestick (LS) CPR with only passive ventilation ('passive'); Group 2 received LS-CPR with synchronized positive pressure ventilations (ppv) at a chest compression ratio of 15:2 (15:2 S); Group 3 had LS-CPR with synchronized ppv at 5:1 (5:1 S); and Group 4 received LS-CPR with asynchronous ppv at 5:1 (5:1 A). Endpoints included hemodynamics, blood gases, minute ventilation, and 24 h outcome. Asynchronous ventilation (5:1 A) had significantly worse hemodynamics including aortic and right atrial systolic, aortic diastolic, and coronary perfusion pressures than the other groups (P<0.05). Passive ventilation had the poorest arterial and mixed venous blood gases (P<0.05), but did not differ from 15:2 S in minute ventilation produced (8 vs 10 l/min). No differences in outcome were seen. The ventilation technique combined with LS-CPR can make a significant difference in hemodynamics as well as ventilation. Optimizing other forms of basic and advanced cardiac life support through different ventilation methods deserves new consideration, including a re-examination of the current single rescuer recommendation of a 15:2 ratio. Optimal ventilation strategy when using the LS device at 60 compressions per min appears to be 5:1 S. Such data is important for conducting clinical trials with this new CPR adjunct. PMID:11801354

Kern, Karl B; Hilwig, Ronald W; Berg, Robert A; Schock, Robert B; Ewy, Gordon A

2002-01-01

100

Impact of Energy Imbalance Tariff on Wind Energy  

SciTech Connect

This paper summarizes the results of a study that uses actual wind power data and actual energy prices to analyze the impact of an energy imbalance tariff imposed by the Federal Energy Regulatory Commission on wind power.

Wan, Y.; Milligan, M.; Kirby, B.

2007-07-01

101

Noninvasive ventilation in postoperative care of lung transplant recipients.  

PubMed

Noninvasive positive pressure ventilation (NIPPV), which provides consolidated treatment of both acute and chronic respiratory failure, is increasingly being used in the postoperative care of lung transplant patients. Graft- and patient-related respiratory insufficiency requiring mechanical ventilation are common features in the postoperative period; they may persist for hours to days. Prolonged intubation, particularly in these immunocompromised patients, has been considered one of the main predisposing factors for developing nosocomial pneumonia. It has been associated with increased length of intensive care unit (ICU) stay as well. Noninvasive mechanical ventilation is nowadays an attractive choice to shorten weaning time and avoid reintubation following lung transplantation. Rapid extubation plus prompt NIPPV application is a useful strategy for lung recipients who do not completely fulfill the criteria for safe extubation. Unloading respiratory muscles, decreasing respiratory rate and sensation of dyspnea, improving ventilation/perfusion abnormalities, decreasing the heart rate, and improving hemodynamics are among the recognized benefits. Adding a noninvasive inspiratory support plus positive end-expiratory pressure (PEEP) to lung transplant recipients has been helpful to prevent airway injury and infections, avoiding the need for reintubation in cases of extubation failure, facilitating nocturnal sedation, treating the post-reimplantation syndrome and postoperative phrenic nerve dysfunction, and preventing reintubation in cases of readmission to the ICU. In our practice, the helmet system has emerged as the preferred interface; in cases of dyshomogeneous dorsobasal lung infiltrates, it allows effective ventilatory support in the prone position as well. PMID:19460554

Feltracco, P; Serra, E; Barbieri, S; Milevoj, M; Furnari, M; Rizzi, S; Rea, F; Marulli, G; Ori, C

2009-05-01

102

Effect of Prone Position on Regional Shunt, Aeration and Perfusion in Experimental Acute Lung Injury  

Microsoft Academic Search

Rationale: The prone position is used to improve gas exchange in patients with acute respiratory distress syndrome. However, the regional mechanism by which the prone position improves gas ex- change in acutely injured lungs is still incompletely defined. Methods:Weusedpositronemissiontomographyimagingof( 13 N)nitro- gen to assess the regional distribution of pulmonary shunt, aeration, perfusion, and ventilation in seven surfactant-depleted sheep in supineandpronepositions.Results:Inthesupineposition,thedorsal

Torsten Richter; Giacomo Bellani; R. Scott Harris; Marcos F. Vidal Melo; Tilo Winkler; Jose G. Venegas; Guido Musch

2005-01-01

103

Perfusion imaging in renal diseases.  

PubMed

Functional imaging of the kidney using radiological techniques has a great potential of development because the functional parameters, which can be approached non-invasively, are multiple. CT can provide measurement of perfusion and glomerular filtration but has the inconvenient to deliver irradiation and potentially nephrotoxicity due to iodine agents in this context. Sonography is able to evaluate perfusion only but quantification remains problematic. Therefore, MR imaging shows the greatest flexibility measuring blood volume and perfusion as well as split renal function. The main applications of perfusion imaging of the kidney are vascular diseases, as renal artery stenosis, renal obstruction and follow-up of renal tumors under antiangiogenic therapy. However, full clinical validation of these methods and the evaluation of their clinical impact are still often worthwhile. PMID:24135032

Grenier, N; Cornelis, F; Le Bras, Y; Rigou, G; Boutault, J R; Bouzgarrou, M

2013-12-01

104

Perfusion MRI of Acute Stroke  

Microsoft Academic Search

\\u000a Perfusion-weighted magnetic resonance imaging (PWI) describes MRI techniques that visually depict hemodynamic conditions at\\u000a the microvascular level. This is in contrast to other vascular MR imaging techniques, notably magnetic resonance angiography\\u000a (MRA) that depict the flow of blood in larger, macroscopically visible vessels. Ischemic damage to brain tissue is caused\\u000a most directly by impairments in microvascular perfusion, rather than by

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

105

Ventilator-associated pneumonia.  

PubMed

Ventilator-associated pneumonia is a pneumonia that develops initially more than 48 h from the start of tracheal intubation and mechanical ventilation. The route of infection is almost always through the respiratory tract. Intake of contaminants from outside the tracheal tube (silent aspiration) is considered a key route, and suctioning of secretions that have accumulated above the cuff of the endotracheal tubes is effective in preventing infection. The circuit is managed and heated-wire humidifiers and suction are manipulated based on appropriate infection control measures. To diagnose pathogens, efforts should be made to collect specimens from the pneumonia focus. Realistically, however, diagnosis can also be achieved based on the clinical course and from the results of culture of samples from tracheal aspirate. Use of prophylactic antimicrobials is not recommended, but once a diagnosis is made, antimicrobials are administered that combat the causative microorganism. PMID:19857223

2009-11-01

106

Hydrostatic determinants of cerebral perfusion  

SciTech Connect

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

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

1986-05-01

107

Difficult mask ventilation.  

PubMed

Mask ventilation is the most fundamental skill in airway management. In this review, we summarize the current knowledge about difficult mask ventilation (DMV) situations. Various definitions for DMV have been used in the literature. The lack of a precise standard definition creates a problem for studies on DMV and causes confusion in data communication and comparisons. DMV develops because of multiple factors that are technique related and/or airway related. Frequently, the pathogenesis involves a combination of these factors interacting to cause the final clinical picture. The reported incidence of DMV varies widely (from 0.08% to 15%) depending on the criteria used for its definition. Obesity, age older than 55 yr, history of snoring, lack of teeth, the presence of a beard, Mallampati Class III or IV, and abnormal mandibular protrusion test are all independent predictors of DMV. These signs should, therefore, be recognized and documented during the preoperative evaluation. DMV can be even more challenging in infants and children, because they develop hypoxemia much faster than adults. Finally, difficult tracheal intubation is more frequent in patients who experience DMV, and thus, clinicians should be familiar with the corrective measures and management options when faced with a challenging, difficult, or impossible mask ventilation situation. PMID:19923516

El-Orbany, Mohammad; Woehlck, Harvey J

2009-12-01

108

Systemic oxygen delivery by peritoneal perfusion of oxygen microbubbles.  

PubMed

Severe hypoxemia refractory to pulmonary mechanical ventilation remains life-threatening in critically ill patients. Peritoneal ventilation has long been desired for extrapulmonary oxygenation owing to easy access of the peritoneal cavity for catheterization and the relative safety compared to an extracorporeal circuit. Unfortunately, prior attempts involving direct oxygen ventilation or aqueous perfusates of fluorocarbons or hemoglobin carriers have failed, leading many researchers to abandon the method. We attribute these prior failures to limited mass transfer of oxygen to the peritoneum and have designed an oxygen formulation that overcomes this limitation. Using phospholipid-coated oxygen microbubbles (OMBs), we demonstrate 100% survival for rats experiencing acute lung trauma to at least 2 h. In contrast, all untreated rats and rats treated with peritoneal oxygenated saline died within 30 min. For rats treated with OMBs, hemoglobin saturation and heart rate were at normal levels over the 2-h timeframe. Peritoneal oxygenation with OMBs was therefore shown to be safe and effective, and the method requires less equipment and technical expertise than initiating and maintaining an extracorporeal circuit. Further translation of peritoneal oxygenation with OMBs may provide therapy for acute respiratory distress syndrome arising from trauma, sepsis, pneumonia, aspiration, burns and other pulmonary diseases. PMID:24439406

Feshitan, Jameel A; Legband, Nathan D; Borden, Mark A; Terry, Benjamin S

2014-03-01

109

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

110

Ventilation in chest trauma  

PubMed Central

Chest trauma is one important factor for total morbidity and mortality in traumatized emergency patients. The complexity of injury in trauma patients makes it challenging to provide an optimal oxygenation while protecting the lung from further ventilator-induced injury to it. On the other hand, lung trauma needs to be treated on an individual basis, depending on the magnitude, location and type of lung or chest injury. Several aspects of ventilatory management in emergency patients are summarized herein and may give the clinician an overview of the treatment possibilities for chest trauma victims. PMID:21769213

Richter, Torsten; Ragaller, Maximilian

2011-01-01

111

Itinerant ferromagnetism in an interacting Fermi gas with mass imbalance  

SciTech Connect

We study the emergence of itinerant ferromagnetism in an ultracold atomic gas with a variable mass ratio between the up- and down-spin species. Mass imbalance breaks the SU(2) spin symmetry, leading to a modified Stoner criterion. We first elucidate the phase behavior in both the grand canonical and canonical ensembles. Second, we apply the formalism to a harmonic trap to demonstrate how a mass imbalance delivers unique experimental signatures of ferromagnetism. These could help future experiments to better identify the putative ferromagnetic state. Furthermore, we highlight how a mass imbalance suppresses the three-body loss processes that handicap the formation of a ferromagnetic state. Finally, we study the time-dependent formation of the ferromagnetic phase following a quench in the interaction strength.

Keyserlingk, C. W. von [Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Conduit, G. J. [Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Physics Department, Ben Gurion University, Beer Sheva 84105 (Israel)

2011-05-15

112

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2013 CFR

...Ventilation plan. A plan of the mine ventilation...annually. The ventilation plan or revisions thereto...written request. The plan shall, where applicable...of internal combustion engine units used underground, including make and model of unit, type of...

2013-07-01

113

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2011 CFR

...Ventilation plan. A plan of the mine ventilation...annually. The ventilation plan or revisions thereto...written request. The plan shall, where applicable...of internal combustion engine units used underground, including make and model of unit, type of...

2011-07-01

114

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2012 CFR

...Ventilation plan. A plan of the mine ventilation...annually. The ventilation plan or revisions thereto...written request. The plan shall, where applicable...of internal combustion engine units used underground, including make and model of unit, type of...

2012-07-01

115

30 CFR 57.8520 - Ventilation plan.  

Code of Federal Regulations, 2010 CFR

...Ventilation plan. A plan of the mine ventilation...annually. The ventilation plan or revisions thereto...written request. The plan shall, where applicable...of internal combustion engine units used underground, including make and model of unit, type of...

2010-07-01

116

30 CFR 57.8520 - Ventilation plan.  

...Ventilation plan. A plan of the mine ventilation...annually. The ventilation plan or revisions thereto...written request. The plan shall, where applicable...of internal combustion engine units used underground, including make and model of unit, type of...

2014-07-01

117

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

118

New ventilated isolation cage.  

PubMed

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 x 28 inches deep x 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. PMID:5659368

Cook, R O

1968-05-01

119

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

120

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

121

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

122

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

123

RESIDENTIAL VENTILATION AND ENERGY CHARACTERISTICS*  

E-print Network

Berkeley, California The role of ventilation in the housing stock is to provide fresh air and to dilute the outdoor air for thermal comfort. Different kinds of ventilation systems have different energy requirements and to estimate the energy savings or penalties associated with tightening or loosening the building envelope

124

Effect of Prone Position on Regional Shunt, Aeration, and Perfusion in Experimental Acute Lung Injury  

PubMed Central

Rationale: The prone position is used to improve gas exchange in patients with acute respiratory distress syndrome. However, the regional mechanism by which the prone position improves gas exchange in acutely injured lungs is still incompletely defined. Methods: We used positron emission tomography imaging of [13N]nitrogen to assess the regional distribution of pulmonary shunt, aeration, perfusion, and ventilation in seven surfactant-depleted sheep in supine and prone positions. Results: In the supine position, the dorsal lung regions had a high shunt fraction, high perfusion, and poor aeration. The prone position was associated with an increase in lung gas content and with a more uniform distribution of aeration, as the increase in aeration in dorsal lung regions was not offset by loss of aeration in ventral regions. Consequently, the shunt fraction decreased in dorsal regions in the prone position without a concomitant impairment of gas exchange in ventral regions, thus leading to a significant increase in the fraction of pulmonary perfusion participating in gas exchange. In addition, the vertical distribution of specific alveolar ventilation became more uniform in the prone position. A biphasic relation between regional shunt fraction and gas fraction showed low shunt for values of gas fraction higher than a threshold, and a steep linear increase in shunt for lower values of gas fraction. Conclusion: In a surfactant-deficient model of lung injury, the prone position improved gas exchange by restoring aeration and decreasing shunt while preserving perfusion in dorsal lung regions, and by making the distribution of ventilation more uniform. PMID:15901611

Richter, Torsten; Bellani, Giacomo; Harris, R. Scott; Melo, Marcos F. Vidal; Winkler, Tilo; Venegas, Jose G.; Musch, Guido

2005-01-01

125

The Isolated Perfused Heart and Its Pioneers.  

PubMed

In 1866, Carl Ludwig together with Elias Cyon created the first isolated perfused frog heart preparation. Perfusion systems for the isolated mammalian heart were developed by H. Newell Martin in 1883 and by Oscar Langendorff in 1895. In its working mode, the isolated perfused rat heart was established in the 1960s. PMID:11390791

Zimmer, Heinz-Gerd

1998-08-01

126

Ventilation and gas exchange in the mute swan, Cygnus olor.  

PubMed

Ventilation and gas exchange have been continuously measured in the mute swan using pneumotachography and breath to breath analysis of the ventilated gas by mass spectrometry combined with blood gas analysis. The breathing frequency was much lower and the tidal volume much higher than values predicted from allometric relations. The breathing cycles typically showed long end-inspiratory breath holding periods. End-tidal PCO2 and PO2 were above and below respectively typical end-tidal gas tensions reported earlier in birds. A pronounced positive PCO2 difference between end-tidal gas and mixed venous blood was present averaging 9.8 mm Hg. The blood-gas values found in the mute swan fall within a range typical of birds. A very low air convection requirement (13.6 ml . ml-1) and high O2 extraction coefficient (33.0%) indicate a high gas exchange efficiency of the swan lung. The unusually large tidal volumes and the long breath holds succeeding each inspiration are likely contributing factors to the high exchange efficiency. Calculated low values for the blood convection requirement (12.8 ml . ml-1) match the low air convection requirements and result in a ventilation/perfusion ratio near unity (VI/Q=1.06). PMID:6770431

Bech, C; Johansen, K

1980-03-01

127

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

128

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

2014-06-01

129

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

130

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

131

Global Imbalances and the U.S. Trade Deficit  

E-print Network

Global Imbalances and the U.S. Trade Deficit By Robert A. Blecker* Revised May 2011 * Professor and Chair, Department of Economics, and Affiliate Faculty, School of International Service, American the prospects for a sustained recovery is the large U.S. trade deficit and the correspondingly large surpluses

Lansky, Joshua

132

Allelic imbalance of 14q32 in esophageal carcinoma  

Microsoft Academic Search

It has been demonstrated that the accumulation of alterations in several oncogenes and tumor suppressor genes plays a role in the initiation and progression of esophageal carcinoma. However, to our knowledge, very few studies have described the molecular genetic changes of chromosome arm 14q in esophageal carcinoma. In this study, we examined 35 primary esophageal carcinomas for allelic imbalance on

Yuji Ihara; Yuji Kato; Tadashi Bando; Fuminori Yamagishi; Tetsuji Minamimura; Takashi Sakamoto; Kazuhiro Tsukada; Masaharu Isobe

2002-01-01

133

Macroeconomic Asymmetry and Imbalance in the Eurozone Catherine SIFAKIS KAPETANAKIS  

E-print Network

crisis, has prompted a growing awareness of the disparities in the economic conditions and competitive advantages of European economic and monetary union, and the costs and risks associated with the system set up the accumulation of lasting imbalances at the expense of Europe's least developed nations. While giving rise

Paris-Sud XI, Université de

134

Gender Imbalance in Accounting Academia: Past and Present  

ERIC Educational Resources Information Center

Studies conducted in the late 1980s and early 1990s reflected a gender imbalance in the accounting academy as the proportion of female professors fell far below the percentage of women accountants in practice. For a sample of doctoral-granting and nondoctoral-granting Association to Advance Collegiate Schools of Business (AACSB) institutions, the…

Jordan, Charles E.; Pate, Gwen R.; Clark, Stanley J.

2006-01-01

135

THE ROLE OF INORGANIC ION IMBALANCE IN AQUATIC TOXICITY TESTING  

EPA Science Inventory

Effluent toxicity testing methods have been well defined, but to a large part have not attempted to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role that various total dissolved solids in effluents have on regula...

136

Thermally induced quasiparticle branch imbalance in thin film superconductors  

Microsoft Academic Search

Thermoelectric effects in superconductors are quite different than in normal metals. One effect is the voltage difference generated between the normal electrons and the superelectrons by a temperature gradient in an electrically isolated thin film of superconductor, the thermally induced quasiparticle branch imbalance. The theoretical background of the effect is investigated, using a two fluid model for the quasiparticle-superelectron system,

P. J. Dolan; P. J. Jr

1984-01-01

137

[The effects of the pause at the end of inspiration on gas exchange and hemodynamics during artificial ventilation].  

PubMed

We have studied the effects of an inspiratory pause (PI) during artificial ventilation in 13 patients in acute respiratory insufficiency. The effects on gas exchange, haemodynamics and distribution of ventilation were observed. During the period of study the total volume, the inspiration/expiration ratio and the inspired oxygen concentration were all maintained constant. With the inspiratory pause arterial oxygenation has not changed significantly, whereas it did change favourably with PEEP. The physiological dead space (VD/VT) was reduced in proportion to the duration of the inspiratory pause. These results suggest that the inspiratory pause triggers regional modification of the ventilation/perfusion ratio, favouring a reduction of the VD/VT ratio. However, this improvement of the VD/VT ratio does not seem to influence the oxygenation or the total distribution of ventilation in this type of patient. PMID:332285

Suter, P M; Jevic, M G; Hemmer, M; Gemperle, M

1977-09-01

138

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

139

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.

NONE

2000-10-12

140

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

141

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

142

Humidity as a Control Parameter for Ventilation  

Microsoft Academic Search

The objective of this study was to develop energy efficient ventilation strategies that will provide both a healthy and comfortable indoor climate and reduce energy consumption compared to present ventilation standards. Humidity was used as a control parameter for the ventilation. Four different ventilation strategies were tested in a test apartment. The results of the experiments indicated that humidity can

Alireza Afshari; Niels C. Bergsøe

2003-01-01

143

Noninvasive Positive Pressure Ventilation in the Emergency  

E-print Network

an Electrolux or Hoover vacuum cleaner to supply air at positive pressure to treat patients with ``cardiacNoninvasive Positive Pressure Ventilation in the Emergency Department Mei-Ean Yeow, MDa , Jairo I ventilators consist of both negative and positive pressure ventilators. Because negative pressure ventilation

144

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

145

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

146

Imbalance response of a rigid rotor supported on end sealed integral squeeze film dampers  

E-print Network

of imbalance, allow the determination of system amplification factors and the Measurements of oil flow rates, impact tests and imbalance response tests demonstrate that end gap seals render a substantial increase in the ISFD viscous damping coefficients...

De Santiago Duran, Oscar Cesar

2012-06-07

147

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

148

Verifying ventilation flows  

SciTech Connect

An innovative technique using a hot-film anemometer has been developed for measuring the flow distribution through generator rotors. When designing large air-cooled generators with the highest efficiency, engineers need to know the total flow rate to the rotor as well as the flow distribution to ensure there are no local hot spots. However, gaining an understanding of generator ventilation has been hampered by a lack of experimental data on rotating machines. Furthermore, while the axial flow distribution along the rotor body can be estimated using standard techniques, such methods average the flow in the circumferential direction. To overcome these limitations, engineers at Westinghouse Electric Corp.`s Power Generation Technology Division in Orlando, Fla., have developed a novel technique for measuring airflow through each vent hole. The technique uses a hot-film anemometer--a velocity-measurement device with a very-high-frequency response--to measure such flows separately while the rotor is spinning at a rated speed of 3,600 rpm.

Laster, W.R. [Westinghouse Electric Corp., Orlando, FL (United States). Power Generation Technology Div.; Sanford, G.W. [Westinghouse Electric Corp., Charlotte, NC (United States)

1996-10-01

149

High frequency jet ventilation and intermittent positive pressure ventilation. Effect of cerebral blood flow in patients after open heart surgery  

SciTech Connect

Attenuation of ventilator-synchronous pressure fluctuations of intracranial pressure has been demonstrated during high frequency ventilation in animal and human studies, but the consequences of this effect on cerebral blood flow have not been investigated in man. We compared the effects of high frequency jet ventilation and intermittent positive pressure ventilation on CBF in 24 patients investigated three hours after completion of open-heart surgery. The patients were investigated during three consecutive periods with standard sedation (morphine, pancuronium): a. IPPV; b. HFJV; c. IPPV. Partial pressure of arterial CO{sub 2} (PaCO{sub 2}: 4.5-5.5 kPa) and rectal temperature (35.5 to 37.5{degree}C) were maintained constant during the study. The CBF was measured by intravenous {sup 133}Xe washout technique. The following variables were derived from the cerebral clearance of {sup 133}Xe: the rapid compartment flow, the initial slope index, ie, a combination of the rapid and the slow compartment flows, and the ratio of fast compartment flow over total CBF (FF). Compared to IPPV, HFJV applied to result in the same mean airway pressure did not produce any change in pulmonary gas exchange, mean systemic arterial pressure, and cardiac index. Similarly, CBF was not significantly altered by HFJV. However, important variations of CBF values were observed in three patients, although the classic main determinants of CBF (PaCO{sub 2}, cerebral perfusion pressure, Paw, temperature) remained unchanged. Our results suggest that in patients with normal systemic hemodynamics, the effects of HFJV and IPPV on CBF are comparable at identical levels of mean airway pressure.

Pittet, J.F.; Forster, A.; Suter, P.M. (University Hospital of Geneva (Switzerland))

1990-02-01

150

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; Cote, Gerard L.

2013-01-01

151

Sectoral Imbalance and Unemployment in the United Kingdom: 1963-84  

Microsoft Academic Search

Quarterly measures of U.K. labor market sectoral imbalance are computed using industrial and regional data. Cyclically corrected measures are used to examine the extent to which changes in sectoral imbalance affect the position of the unemployment-vacancy rule curve. The substantial increase in industrial imbalance beginning in 1980 is estimated to have accounted for an increase in the unemployment rate, measured

George W Evans

1993-01-01

152

Global imbalances: as giants evolve - a conference sponsored by the Federal Reserve Bank of Boston  

Microsoft Academic Search

“Global imbalances” are currently attracting much attention in policy and financial circles. In most official forecasts the threat of a disorderly correction of these huge imbalances appears as a key risk to the global outlook. While the phrase generally refers to net deficits or surpluses in international trade and investment, when these imbalances are large and persistent, they usually reflect

anonymous

2006-01-01

153

The role of grade sensitivity in explaining the gender imbalance in undergraduate economics  

Microsoft Academic Search

There is a gender imbalance in undergraduate economics departments with most departments educating a strong majority of young men. This imbalance has led many economists to ponder the question of why relatively few women choose to take courses and major in economics. Our hypothesis is that the gender imbalance in undergraduate economics, particularly at institutions with traditional liberal arts curriculums,

Kevin Rask; Jill Tiefenthaler

2008-01-01

154

Different nutritional states and autonomic imbalance in childhood.  

PubMed

Autonomic imbalance, measured as heart rate variability (HRV), and an increased cardiovascular risk are described for overweight children, as well as for patients with anorexia nervosa. We investigate whether body mass index or actual caloric intake influences HRV. In our cross-sectional study, we compared HRV parameters for a healthy control group (n=52), anorexia nervosa patients (n=17), thin (n=18) and overweight children (n=19). Anorexia nervosa patients showed significantly lower heart rates at night (P<0.001) and significantly higher SDNN (standard deviation of all RR-intervals) (P<0.001 ), whereas overweight children showed an opposing pattern. SDNN and heart rate at night are highly correlated (r=0.89, R(2)=0.79, P<0.001). We conclude that not current body mass index but caloric intake determines HRV. Obesity and anorexia nervosa are characterized by a specific pattern of autonomic imbalance. PMID:25248356

Dippacher, S; Willaschek, C; Buchhorn, R

2014-11-01

155

Spinal pedicle subtraction osteotomy for fixed sagittal imbalance patients  

PubMed Central

In addressing spinal sagittal imbalance through a posterior approach, the surgeon now may choose from among a variety of osteotomy techniques. Posterior column osteotomies such as the facetectomy or Ponte or Smith-Petersen osteotomy provide the least correction, but can be used at multiple levels with minimal blood loss and a lower operative risk. Pedicle subtraction osteotomies provide nearly 3 times the per-level correction of Ponte/Smith-Petersen osteotomies; however, they carry increased technical demands, longer operative time, and greater blood loss and associated significant morbidity, including neurological injury. The literature focusing on pedicle subtraction osteotomy for fixed sagittal imbalance patients is reviewed. The long-term overall outcomes, surgical tips to reduce the complications and suggestions for their proper application are also provided. PMID:24340276

Hyun, Seung-Jae; Kim, Yongjung J; Rhim, Seung-Chul

2013-01-01

156

MMSE WL Equalizer in Presence of Receiver IQ Imbalance  

Microsoft Academic Search

In this correspondence, with reference to the transmission over a linear time-dispersive channel, we address the problem of the in-phase and quadrature-phase (IQ) imbalance compensation when a single-carrier modulation scheme is used. Low-cost fabrication technologies and high data-rate transmissions render the conventional receivers very sensitive to the imperfections of their analog stage and, hence, proper countermeasures need to be adopted.

Davide Mattera; Luigi Paura; Fabio Sterle

2008-01-01

157

Human APC2 Localization and Allelic Imbalance1  

Microsoft Academic Search

A second adenomatous polyposis coli (APC)-like gene, APC2\\/APCL, was recently described and localized to chromosome 19. We have fine mapped APC2 to a small region of chromosome 19p13.3 containing mark- ers D19S883 and WI-19632, a region commonly lost in a variety of cancers, particularly ovarian cancer. Interphase fluorescence in situ hy- bridization analysis revealed an APC2 allelic imbalance in 19

Christy Rothwell Jarrett; Jan Blancato; Tin Cao; D. S. Bressette; M. Cepeda; Paul E. Young; C. Richter King; Stephen W. Byers

2001-01-01

158

Chronic cholinergic imbalances promote brain diffusion and transport abnormalities  

Microsoft Academic Search

Cholinergic imbalances occur after traumatic effects and in the initial stages of neuro- degenerative diseases, but their long-lasting effects remained largely unexplained. To address this, we used TgS transgenic mice constitutively overexpress- ing synaptic acetylcholinesterase (AChE-S) and pre- senting a complex phenotype of progressive neuro- deterioration. T1- and T2-weighted magnetic resonance (MR) brain images appeared similar. How- ever, diffusion-weighted MRI

Eran Meshorer; Inbal E. Biton; Yoram Ben-Shaul; Shani Ben-Ari; Yaniv Assaf; Hermona Soreq; Yoram Cohen

2005-01-01

159

Child Underreporting, Fertility, and Sex Ratio Imbalance in China  

Microsoft Academic Search

Child underreporting is often neglected in studies of fertility and sex ratio imbalance in China. To improve estimates of\\u000a these measures, I use intercensal comparisons to identify a rise in underreporting, which followed the increased enforcement\\u000a and penalization under the birth planning system in 1991. A new triangulation of evidence indicates that about 19% of children\\u000a at ages 0–4 were

Daniel Goodkind

2011-01-01

160

Vorticity imbalance and stability in relation to convection  

E-print Network

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 con- vection indicate systematic imbalance in the terms... developed along a quasi- stationary polar front through the midwest in response to two relatively weak short wave perturbations in the upper levels. The first short wave was centered in the Midwest at the start of the experiment and a squall line...

Read, William Light

2012-06-07

161

Polygonalization of Wheel Treads Caused by Static and Dynamic Imbalances  

NASA Astrophysics Data System (ADS)

High speed wheelsets of railway systems differ from classical ones. These dynamics are determined by gyroscopic and inertia moments. A dynamical model with 40-DOF was generated using elastic beam elements to describe the axle, connected to rigid wheel and brake disks. Imbalance calculations and wear simulations were carried out resulting in polygonalization of the circular wheel surface. Even when starting the simulation with wheels of constant radius, the unroundness grows to unacceptable values.

MEINKE, P.; MEINKE, S.

1999-11-01

162

Chromosomal imbalances in carcinoma showing thymus-like elements (CASTLE).  

PubMed

Carcinoma showing thymus-like elements (CASTLE) is a rare neoplasm of the thyroid gland resembling lymphoepithelioma-like and squamous cell carcinoma of the thymus and is thought to arise from ectopic thymic tissue within the thyroid gland or rudimentary branchial pouches along the thymic line. Using comparative genomic hybridization (CGH), chromosomal imbalances have been detected in several types of thymomas and thymic carcinomas. To evaluate whether there are hints of an underlying sequence in the pathogenesis of CASTLE analogue to those found in thymomas and thymic carcinomas, we evaluated four of these rare neoplasms for chromosomal imbalances using CGH. The most frequent gains were seen on chromosomal arm 1q (3/4), and losses were most frequently detected on 6p (4/4), 6q (3/4) and 16q (3/4). These CGH data show that CASTLE is characterized by chromosomal imbalances similar to those found in thymomas and thymic carcinomas and indicate a similar sequence in tumour development. PMID:21735166

Veits, Lothar; Mechtersheimer, Gunhild; Steger, Christina; Freitag, Jens; Mikuz, Gregor; Schmid, Kurt W; Hofmann, Walter; Schirmacher, Peter; Hartmann, Arndt; Rieker, Ralf J

2011-08-01

163

Flux emergence, flux imbalance, magnetic free energy and solar flares  

NASA Astrophysics Data System (ADS)

Emergence of complex magnetic flux in the solar active regions lead to several observational effects such as a change in sunspot area and flux embalance in photospheric magnetograms. The flux emergence also results in twisted magnetic field lines that add to free energy content. The magnetic field configuration of these active regions relax to near potential-field configuration after energy release through solar flares and coronal mass ejections. In this paper, we study the relation of flare productivity of active regions with their evolution of magnetic flux emergence, flux imbalance and free energy content. We use the sunspot area and number for flux emergence study as they contain most of the concentrated magnetic flux in the active region. The magnetic flux imbalance and the free energy are estimated using the HMI/SDO magnetograms and Virial theorem method. We find that the active regions that undergo large changes in sunspot area are most flare productive. The active regions become flary when the free energy content exceeds 50% of the total energy. Although, the flary active regions show magnetic flux imbalance, it is hard to predict flare activity based on this parameter alone.

Choudhary, Debi Prasad; Gosain, Sanjay; Gopalswamy, Nat; Manoharan, P. K.; Chandra, R.; Uddin, W.; Srivastava, A. K.; Yashiro, S.; Joshi, N. C.; Kayshap, P.; Dwivedi, V. C.; Mahalakshmi, K.; Elamathi, E.; Norris, Max; Awasthi, A. K.; Jain, R.

2013-10-01

164

Contaminants in ventilated filling boxes  

NASA Astrophysics Data System (ADS)

While energy efficiency is important, the adoption of energy-efficient ventilation systems still requires the provision of acceptable indoor air quality. Many low-energy systems, such as displacement or natural ventilation, rely on temperature stratification within the interior environment, always extracting the warmest air from the top of the room. Understanding buoyancy-driven convection in a confined ventilated space is key to understanding the flow that develops with many of these modern low-energy ventilation schemes. In this work we study the transport of an initially uniformly distributed passive contaminant in a displacement-ventilated space. Representing a heat source as an ideal sourced of buoyancy, analytical and numerical models are developed that allow us to compare the average efficiency of contaminant removal between traditional mixing and modern low-energy systems. A set of small-scale analogue laboratory experiments was also conducted to further validate our analytical and numerical solutions.We find that on average traditional and low-energy ventilation methods are similar with regard to pollutant flushing efficiency. This is because the concentration being extracted from the system at any given time is approximately the same for both systems. However, very different vertical concentration gradients exist. For the low-energy system, a peak in contaminant concentration occurs at the temperature interface that is established within the space. This interface is typically designed to sit at some intermediate height in the space. Since this peak does not coincide with the extraction point, displacement ventilation does not offer the same benefits for pollutant flushing as it does for buoyancy removal.

Bolster, D. T.; Linden, P. F.

165

Animal models of ex vivo lung perfusion as a platform for transplantation research  

PubMed Central

Ex vivo lung perfusion (EVLP) is a powerful experimental model for isolated lung research. EVLP allows for the lungs to be manipulated and characterized in an external environment so that the effect of specific ventilation/perfusion variables can be studied independent of other confounding physiologic contributions. At the same time, EVLP allows for normal organ level function and real-time monitoring of pulmonary physiology and mechanics. As a result, this technique provides unique advantages over in vivo and in vitro models. Small and large animal models of EVLP have been developed and each of these models has their strengths and weaknesses. In this manuscript, we provide insight into the relative strengths of each model and describe how the development of advanced EVLP protocols is leading to a novel experimental platform that can be used to answer critical questions in pulmonary physiology and transplant medicine. PMID:24977117

Nelson, Kevin; Bobba, Christopher; Ghadiali, Samir; Jr, Don Hayes; Black, Sylvester M; Whitson, Bryan A

2014-01-01

166

Cigarette smoke ventilation decreases prostaglandin inactivation in rat and hamster lungs  

SciTech Connect

The effects of cigarette smoke on the metabolism of exogenous PGE2 and PGF2 alpha were investigated in isolated rat and hamster lungs. When isolated lungs from animals were ventilated with cigarette smoke during pulmonary infusion of 100 nmol of PGE2 or PGF2 alpha, the amounts of the 15-keto-metabolites in the perfusion effluent were decreased. Pre-exposure of animals to cigarette smoke daily for 3 weeks did not change the metabolism of PGE2 when the lungs were ventilated with air. Cigarette smoke ventilation of lungs from pre-exposed animals caused, however, a similar decrease in the metabolism of PGE2 as in animals not previously exposed to smoke. After pulmonary injection of 10 nmol of /sup 14/C-PGE2 the radioactivity appeared more rapidly in the effluent during cigarette smoke ventilation suggesting inhibition of the PGE2 uptake mechanism. In rat lungs pulmonary vascular pressor responses to PGE2 and PGF2 alpha were inhibited by smoke ventilation.

Maennistoe, J.; Uotila, P.

1982-06-01

167

Musculoskeletal pain and effort-reward imbalance- a systematic review  

PubMed Central

Background Musculoskeletal pain may be triggered by physical strains and psychosocial risk factors. The effort-reward imbalance model (ERI model) is a stress model which measures psychosocial factors in the working world. The question is whether workers with an effort-reward imbalance report musculoskeletal pain more frequently than those with no effort-reward imbalance. A systematic review using a best evidence synthesis approach was conducted to answer this question. Methods A literature search was conducted for the period from 1996 to 2012, using three databases (Pubmed, Embase and PsycINFO). The research criteria related to psychosocial, work-related stress as per the ERI model and to musculoskeletal pain. A quality score was developed using various quality criteria to assess the standard of the studies. The level of evidence was graded as in (Am J Ind Med 39:180–193, 2001). Results After applying the inclusion criteria, a total of 19 studies were included in the review: 15 cross-sectional studies, three prospective studies and one case–control study. 74% of all studies exhibited good methodological quality, 53% collected data using the original ERI questionnaire, and in 42% of the studies, there was adequate control for physical working conditions. Furthermore, different cut-off points were used to classify exposed and non-exposed individuals. On the basis of 13 studies with a positive, statistically significant association, a moderate level of evidence was inferred for the association between effort-reward imbalance and musculoskeletal pain. The evidence for a role of over-commitment and for its interaction with effort-reward imbalance was rated as inconclusive - on the basis of eight and five studies, respectively. Conclusions On the basis of the available evidence, no reliable conclusion may be drawn about any association between the psychosocial factors ascertained using the ERI model and musculoskeletal pain. Before a reliable statement can be made on the association between ERI and musculoskeletal pain, additional longitudinal studies must be performed - with a standardised method for recording and classifying exposure, as well as control of physical confounders. Appropriate preventive measures can then be specified. PMID:24428955

2014-01-01

168

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

169

Lung-lung interaction in isolated perfused unilateral hyperventilated rat lungs.  

PubMed

The technique of conducting high tidal volume (TV) ventilation-induced lung inflammation including remote organs is still open to discussion, and our aim is to investigate this issue in isolated ventilated rat lungs perfused with salt solution. Selective right lung (RL) hyperventilation (TV of 15 mL/kg with air containing 5% CO(2) on zero or 2.5 cm H(2)0 end expiratory pressure [ZEEP or PEEP] in addition to left lung (LL) on 2.5 cm H(2)0 continuous positive airway pressure (CPAP) for 60 min, was realized after 30 min both lungs ventilation by occluding the left main bronchus, and it was allocated to the following 5 groups: groups 1 and 2 underwent hyperventilation under ZEEP, groups 3 and 4 underwent hyper ventilation under PEEP with recirculation or nonrecirculation (R-ZEEP or NR-ZEEP and R-PEEP or NR-PEEP), and group 5 served as the control group. Recirculation means the same perfusate recirculates the system throughout the procedure. The wet/dry ratio and protein content of bronchoalveolar lavage fluid (Prot-BALF), cytokine messenger RNAs (mRNAs), localization of tumor necrosis factor-alpha (TNF-alpha) by immunofluorescence double staining, and TNF-alpha concentration in the perfusate and BALF in each lung were measured and compared between groups by Kruskal-Wallis test. Lung injury (increased wet/dry ratio, Prot-BALF, and TNF-alpha on endothelial and epithelial cells) was shown in the hyperventilated RLs with ZEEP compared with their corresponding CPAP LLs. PEEP prevented these injuries. Lung injury was also demonstrated in the recirculated LL compared with the nonrecirculated LL (Prot-BALF, TNF-alpha and interleukin-1beta [IL-1beta] mRNAs: the LL of the R-ZEEP is greater than the LL of NR-ZEEP by P < 0.01). Unilateral hyperventilated lungs with ZEEP induced TNF-alpha, increased permeability, and injured the control lung via perfusion. PMID:20403578

Bilali, Aishan; Kurata, Shunichi; Ikeda, Satoshi; Georgieva, Gabriela S; Zhu, Chenting; Tomita, Makoto; Katoh, Iyoko; Mitaka, Chieko; Eishi, Yoshinobu; Imai, Takasuke

2010-05-01

170

Visualization of Myocardial Perfusion Derived from Coronary Anatomy  

E-print Network

on the perfusion of the heart muscle in patients with coronary artery disease remains a challenging task. We, coronary artery territories, myocardial perfusion. 1 Introduction Coronary Artery Disease (CADVisualization of Myocardial Perfusion Derived from Coronary Anatomy Maurice Termeer, Javier Oliv

171

Interplay between Nuclear Factor Erythroid 2-Related Factor 2 and Amphiregulin during Mechanical Ventilation.  

PubMed

Mechanical ventilation (MV) elicits complex and clinically relevant cellular responses in the lungs. The current study was designed to define the role of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), a major regulator of the cellular antioxidant defense system, in the pulmonary response to MV. Nrf2 activity was quantified in ventilated isolated perfused mouse lungs (IPL). Regulation of amphiregulin (AREG) was investigated in BEAS-2B cells with inactivated Nrf2 or Keap1, the inhibitor of Nrf2, using a luciferase vector with AREG promoter. AREG-dependent Nrf2 activity was examined in BEAS-2B cells, murine precision-cut lung slices (PCLS), and IPL. Finally, Nrf2 knockout and wild-type mice were ventilated to investigate the interplay between Nrf2 and AREG during MV in vivo. Lung functions and inflammatory parameters were measured. Nrf2 was activated in a ventilation-dependent manner. The knockdown of Nrf2 and Keap1 via short hairpin RNA in BEAS-2B cells and an EMSA with lung tissue revealed that AREG is regulated by Nrf2. Conversely, AREG application induced a significant Nrf2 activation in BEAS-2B cells, PCLS, and IPL. The signal transduction of ventilation-induced Nrf2 activation was shown to be p38 MAP kinase-dependent. In vivo ventilation experiments indicated that AREG is regulated by Nrf2 during MV. We conclude that Areg expression is regulated by Nrf2. During high-pressure ventilation, Nrf2 becomes activated and induces AREG, leading to a positive feedback loop between Nrf2 and AREG, which involves the p38 MAPK and results in the expression of cytoprotective genes. PMID:24921206

Reiss, Lucy Kathleen; Fragoulis, Athanassios; Siegl, Stephanie; Platen, Christopher; Kan, Yuet Wai; Nautiyal, Jaya; Parker, Malcom; Pufe, Thomas; Uhlig, Ulrike; Martin, Christian; Uhlig, Stefan; Wruck, Christoph Jan

2014-11-01

172

The Imbalance of Water in Nature as System  

NASA Astrophysics Data System (ADS)

Consider some of the water-containing area. Choose some the factors which we consider important to the system. The system contains a system factors, and the external environment these factors doesn't contain. Between the system and the external environment must be some flows into the system, out of the system and along the border. If the flows into and out of the system are not equal, that means within the system exactly something is happening. But the equality of the flows into and out of the system does not mean that within the system nothing happens. It is extremely important to determine the time factor. Everything has a beginning and an end. Each factor has its own life from 0 to 1, as well as their watches. Thus that within the system and the environment at the same time are going a lot of the watches and each watch is going by their own pace. System-wide time is needed to describe the system as a whole and to be able to re-measure the individual time of each factor. It is also very important to identify each factor of the system, environment and border. Definition of each particular factor depends on the level of our knowledge. There are many examples where one factor was divided into several, and vice versa, several factors have combined in one or even disappear as a non-existent. Each factor is determined by specific people for reasons of convenience, the specific of tasks, the possible accuracy of measurement, available resources, etc. The development of the science and applications are going to the direction of the clearer separation of factors and the precision of their measurements. Now is extremely important to more clearly define the boundaries of systems, factors and the allowed accuracy of their measurements. With such a revision, many previously balanced situations become to the imbalance. There are many specific details for each case, but they do not change the basic approach described above. If not clearly resolved the questions listed above so will not be obtained any reliable results. For example, the real water arrival occurs in the modes of imbalances such as increasing or decreasing. Water departure also is some set of the several imbalance increase and decrease types. The processes with various orientations interact between each other and reinforce or depress the conjoint effect. This creates some unstable situation, which are not visible by the balanced approach. Therefore some natural disasters actually are coming as unexpected. But in really there are some consequences of the methodological blindness. The Nature is unstable. The imbalance is the main state of the Nature. But mankind does not yet have adequate tools to describing imbalance as it is. In generally now is used more or less successful extrapolation and interpolation of the balance logic. But this is not enough now. So we tried to sharpen here the importance of the works with the imbalance directly.

Kontar, V. A.; Imbalance of Water in Nature

2011-12-01

173

Ionic imbalance due to hydrogen carbonate from Asian dust  

NASA Astrophysics Data System (ADS)

In an attempt to identify the ionic imbalance, hydrogen carbonate, HCO 3- (bicarbonate), was determined together with the commonly determined nine major ions because the imbalance was frequently encountered in the chemical analysis of samples with high pHs. Titration method was applied for the determination of the samples with pH higher than 5.6. These samples amounted to 102 of the 1536 samples collected in Hokkaido, Northern Japan, from April 1998 to December 2002. Of the 102 samples, 74 (Group A) showed an acceptable ion balance without including HCO 3-. In the other 28 (Group B), however, inclusion of HCO 3- successfully improved the ion balance. These results suggested that hydrogen carbonate was a potential candidate for explaining the imbalance. The hydrogen carbonate concentrations showed a strong correlation with the corresponding non-sea salt calcium (nss-Ca 2+) concentrations, which implied that hydrogen carbonate was derived from calcium carbonate particles incorporated into falling raindrops or cloud droplets. For Group A, the relationship between hydrogen carbonate and the nss-calcium ion concentration was very similar to that for commonly suspended particles in Hokkaido. On the other hand, Group B exhibited a stronger but significantly different correlation. To the samples of Group B, a back-trajectory analysis was applied to demonstrate that the samples were associated with aerosol travelling from Northern China or Mongolia, which indicated that alkaline aerosol affected the chemistry. In consideration of these findings, the current standard of the ion balance should be critically reviewed for modification in regard to the contribution of hydrogen carbonate not only in source areas but also in receptor areas of alkaline aerosol.

Noguchi, Izumi; Hara, Hiroshi

174

REVIEW ARTICLES Dobutamine Stress Myocardial Perfusion Imaging  

Microsoft Academic Search

In patients with limited exercise capacity and (relative) contraindications to direct vasodilators such as dipyridamole or adenosine, dobutamine stress nuclear myocardial perfusion imaging (DSMPI) represents an alternative, exercise-independent stress modality for the detection of coronary artery disease (CAD). Nondiagnostic test results (absence of reversible perfusion defects with submaximal stress) do occur in approximately 10% of patients. Serious side effects during

Marcel L. Geleijnse; Abdou Elhendy; Paolo M. Fioretti; Jos R. T. C. Roelandt

175

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

SciTech Connect

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

Mullani, N.A.

1984-11-01

176

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

177

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

178

14 CFR 252.9 - Ventilation systems.  

...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...

2014-01-01

179

14 CFR 252.9 - Ventilation systems.  

Code of Federal Regulations, 2012 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...

2012-01-01

180

14 CFR 252.9 - Ventilation systems.  

Code of Federal Regulations, 2013 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...

2013-01-01

181

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...The terminals shall be equipped with acceptable flame screens. (b) Chemical laboratories shall be equipped with power ventilation...Ventilation of air conditioning systems serving the chemical laboratory shall be designed so that air...

2010-10-01

182

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...The terminals shall be equipped with acceptable flame screens. (b) Chemical laboratories shall be equipped with power ventilation...Ventilation of air conditioning systems serving the chemical laboratory shall be designed so that air...

2013-10-01

183

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...The terminals shall be equipped with acceptable flame screens. (b) Chemical laboratories shall be equipped with power ventilation...Ventilation of air conditioning systems serving the chemical laboratory shall be designed so that air...

2011-10-01

184

Western Interconnection Energy Imbalance Market Status and Prospects (Presentation)  

SciTech Connect

This presentation describes how a new wholesale electricity market for energy imbalance ancillary services could be implemented and operated. Some conclusions of this presentation are: (1) Method for calculating additional reserve requirements due to wind and solar production; (2) EIM results in substantial reduction in reserves requirements and ramping demand; (3) Reduced participation reduces benefits for all but reduces the benefits to non-participants the most; (4) Full participation leads to maximum benefit across the Western Interconnection, up to 42% of total reserve requirement; and (5) Regional EIM implementations have smaller but substantial benefits.

Milligan, M.; Kirby, B.; King, J.; Beuning, S.

2011-10-01

185

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

186

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

187

Humidity Implications for Meeting Residential Ventilation Requirements  

E-print Network

for Meeting Residential Ventilation Requirements ABSTRACT In 2003 ASHRAE approved the nation's first1 LBNL-62182 Humidity Implications for Meeting Residential Ventilation Requirements Iain S. Walker residential ventilation standard, ASHRAE Standard 62.2. Because meeting this standard can significantly change

188

Quality control of mechanical ventilation at the patient's home  

Microsoft Academic Search

Objective. During home mechanical ventilation the prescribed settings are applied without permanent supervision of health professionals. After a long-time period of unattended operation at home the ventilator may not apply the ventilation parameters prescribed. This quality control study of home mechanical ventilation assessed whether tidal volume (VT), frequency (f), and minute ventilation (V' E) actually applied by the ventilator coincide

Ramon Farré; Esther Giró; Vinyet Casolivé; Daniel Navajas; Joan Escarrabill

2003-01-01

189

46 CFR 153.312 - Ventilation system standards.  

Code of Federal Regulations, 2010 CFR

...must be operable from outside the space it ventilates. (e) A ventilation...change the air in the ventilated space at least 30 times per hour. (f) A ventilation...stagnate in any part of a ventilated space. (g) A ventilation...

2010-10-01

190

46 CFR 153.312 - Ventilation system standards.  

...must be operable from outside the space it ventilates. (e) A ventilation...change the air in the ventilated space at least 30 times per hour. (f) A ventilation...stagnate in any part of a ventilated space. (g) A ventilation...

2014-10-01

191

Unilateral high frequency jet ventilation  

Microsoft Academic Search

A young alcoholic presented with severe bilateral bronchopneumonia, which required prolonged treatment with intermittent positive pressure ventilation. High airway pressures were necessary for effective gas exchange. A recurrent tension pneumothorax led to a persistent bronchopleural fistula which resulted in hypercarbia and hypoxaemia despite the use of large minute volumes. Surgical resection was not considered feasible because of extensive local infection.

A. J. Mortimer; P. S. Laurie; H. Garrett; J. H. Kerr

1984-01-01

192

Thermally induced quasiparticle branch imbalance in thin film superconductors  

SciTech Connect

Thermoelectric effects in superconductors are quite different than in normal metals. One effect is the voltage difference generated between the normal electrons and the superelectrons by a temperature gradient in an electrically isolated thin film of superconductor, the thermally induced quasiparticle branch imbalance. The theoretical background of the effect is investigated, using a two fluid model for the quasiparticle-superelectron system, with attention being given to the question of thermal contract between the sample (thin Sn film) and the (sapphire) substrate. Sample fabrication, using liftoff photolithography to pattern normal metal (Ag) tunnel junction probes (which sample the potential of the quasiparticles) is discussed, as is the experimental apparatus, and the scheme for making measurements using a SQUID picovoltmeter. The thermopower of Sn films in the normal state was measured to be between .19 and 1.4 nV/K, varying with thickness of the film, a value which is considerably smaller than the bulk value of 20 nV/K. An experimental upper bound was placed on the branch imbalance voltage of 10 pV, which gives an upper bound for the thermopower of the normal electrons in the superconductor of 2 nV/K, in agreement with the theory presented.

Dolan, P.J. Jr.

1984-01-01

193

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

194

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

195

Evaluation of hemodynamic perfusion MR images.  

PubMed

Perfusion normally refers to the delivery of blood at the level of capillaries. Hemodynamic perfusion magnetic resonance (MR) imaging has been used in clinics for a series of applications including tumor characterization (histological type diagnosis and grading), diagnosis and the follow up of stroke, and several other disorders. For this study a platform to investigate the theoretical basis of perfusion imaging was developed. Using dynamic measurements of contrast agents in magnetic resonance imaging (MRI) relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and mean transit time (MTT) are calculated. These three parameters are quantized, and displayed as color images for diagnostic and follow up studies. The comparative studies in MR perfusion must address issues such as; image registration, region of interest (ROI) selection, threshold identification and quantization of rCBV, rCBF and rMTT. The evaluation process involved the comparison of the diagnostic capabilities of the three perfusion images (rCBV, rCBF, MTT). Digital Substraction angiography was used as the gold standard in these comparisons. The study group comprises 16 patients with the diagnosis of subarachnoid bleeding and intracranial aneurysms. The proposed cerebral MR perfusion analysis system has been accepted by the radiologists as a useful tool for their perfusion studies and clinical evaluation. PMID:17281575

Agus, Onur; Ozkan, Mehmed; Aydin, Kubilay; Sahinbas, Muge; Sencer, Serra

2005-01-01

196

Imbalance Fault Detection of Direct-Drive Wind Turbines Using Generator Current Signals  

Microsoft Academic Search

Imbalance faults constitute a significant portion of all faults in wind turbine generators (WTGs). WTG imbalance fault detection using generator current measurements has advantages over traditional vibration-based methods in terms of cost, implementation, and system reliability. However, there are challenges in using current signals for imbalance fault detection due to low signal-to-noise ratio of the useful information in current signals

Xiang Gong; Wei Qiao

2012-01-01

197

Joint estimation of carrier frequency offset and IQ imbalance for 4G mobile wireless systems  

Microsoft Academic Search

In the context of 4G wireless mobile systems with direct conversion receivers, an new algorithm for carrier frequency offset (CFO) and IQ-imbalance estimation and compensation at the receiver is proposed. All processing for estimation and compensation of both CFO and IQ-imbalance is done in the time domain. Because the CFO is estimated while taking into account the presence of IQ-imbalance,

Stefaan De Rore; Eduardo Lopez-Estraviz; F. Horlin; L. Van der Perre

2006-01-01

198

Impacts of I\\/Q imbalance on QPSK-OFDM-QAM detection  

Microsoft Academic Search

The impacts of the I\\/Q imbalance in the quadrature down-converter on the performance of a QPSK-OFDM-QAM system are studied. Either amplitude or phase imbalance introduces inter-channel interference (ICI). In addition to the ICI, there is a cross-talk between in-phase and quadrature channels in each and every sub-carrier when both amplitude and phase imbalances are present. The BER (bit error ratio)

Chia-Ling Liu

1998-01-01

199

Pulmonary Perfused Blood Volume with Dual-Energy CT as Surrogate for Pulmonary Perfusion Assessed with Dynamic Multidetector CT  

PubMed Central

Purpose: To compare measurements of regional pulmonary perfused blood volume (PBV) and pulmonary blood flow (PBF) obtained with computed tomography (CT) in two pig models. Materials and Methods: The institutional animal care and use committee approved all animal studies. CT-derived PBF and PBV were determined in four anesthetized, mechanically ventilated, supine swine by using two methods for creating pulmonary parenchymal perfusion heterogeneity. Two animals were examined after sequentially moving a pulmonary arterial balloon catheter from a distal to a central location, and two others were examined over a range of static airway pressures, which varied the extents of regional PBF. Lung sections were divided into blocks and Pearson correlation coefficients calculated to compare matching regions between the two methods. Results: CT-derived PBF, CT-derived PBV, and their associated coefficients of variation (CV) were closely correlated on a region-by-region basis in both the balloon occlusion (Pearson R = 0.91 and 0.73 for animals 1 and 2, respectively; Pearson R = 0.98 and 0.87 for comparison of normalized mean and CV for animals 1 and 2, respectively) and lung inflation studies (Pearson R = 0.94 and 0.74 for animals 3 and 4, respectively; Pearson R = 0.94 and 0.69 for normalized mean and CV for animals 3 and 4, respectively). When accounting for region-based effects, correlations remained highly significant at the P < .001 level. Conclusion: CT-derived PBV heterogeneity is a suitable surrogate for CT-derived PBF heterogeneity. ©RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112789/-/DC1 PMID:23192773

Fuld, Matthew K.; Halaweish, Ahmed F.; Haynes, Susan E.; Divekar, Abhay A.; Guo, Junfeng

2013-01-01

200

Non-invasive ventilation in prone position for refractory hypoxemia after bilateral lung transplantation.  

PubMed

Temporary graft dysfunction with gas exchange abnormalities is a common finding during the postoperative course of a lung transplant and is often determined by the post-reimplantation syndrome. Supportive measures including oxygen by mask, inotropes, diuretics, and pulmonary vasodilators are usually effective in non-severe post-reimplantation syndromes. However, in less-responsive clinical pictures, tracheal intubation with positive pressure ventilation, or non-invasive positive pressure ventilation (NIV), is necessary. We report on the clinical course of two patients suffering from refractory hypoxemia due to post-reimplantation syndrome treated with NIV in the prone and Trendelenburg positions. NIV was well tolerated and led to resolution of atelectactic areas and dishomogeneous lung infiltrates. Repeated turning from supine to prone under non invasive ventilation determined a stable improvement of gas exchange and prevented a more invasive approach. Even though NIV in the prone position has not yet entered into clinical practice, it could be an interesting option to achieve a better match between ventilation and perfusion. This technique, which we successfully applied in lung transplantation, can be easily extended to other lung diseases with non-recruitable dorso-basal areas. PMID:19637990

Feltracco, Paolo; Serra, Eugenio; Barbieri, Stefania; Persona, Paolo; Rea, Federico; Loy, Monica; Ori, Carlo

2009-01-01

201

[The effect of non-invasive mechanical ventilation in postoperative respiratory failure].  

PubMed

Postoperative respiratory failure is related with the highest mortality and morbidity among all perioperative complications. The most common underlying mechanism of postoperative respiratory failure is the development of atelectasis. Anaesthesia, medications which cause respiratory depression, high FiO2 use, postoperative pain and disruption of muscle forces due to surgery leads to decrease in functional residual capacity and results in atelectasis formation. Atelectasis causes severe hypoxemia due to ventilation, perfusion mismatch, shunt and increased peripheral vascular resistance. Intrathoracic positive pressure is an effective therapeutic option in both prevention and treatment of atelectasis. Non-invasive mechanical ventilation is related with a lower mortality and morbidity rate due to lack of any potential complication risks of endotracheal intubation. Non-invasive mechanical ventilation can be applied as prophylactic or curative. Both of these techniques are related with lower reintubation rates, nosocomial infections, duration of hospitalization and mortality in patients with postoperative respiratory failure. The differences of this therapy from standard application and potential complications should be well known in order to improve prognosis in these group of patients. The primary aim of this review is to underline the pathogenesis of postoperative respiratory failure. The secondary aim is to clarify the optimum method, effect and complications of non-invasive mechanical ventilation therapy under the light of the studies which was performed in specific patient groups. PMID:22779943

Ozy?lmaz, Ezgi; Kaya, Ak?n

2012-01-01

202

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

203

Models for prediction of temperature difference and ventilation effectiveness with displacement ventilation  

SciTech Connect

Displacement ventilation may provide better indoor air quality than mixing ventilation. Proper design of displacement ventilation requires information concerning the air temperature difference between the head and foot level of a sedentary person and the ventilation effectiveness at the breathing level. This paper presents models to predict the air temperature difference and the ventilation effectiveness, based on a database of 56 cases with displacement ventilation. The database was generated by using a validated CFD program and covers four different types of US buildings: small offices, large offices with partitions, classrooms, and industrial workshops under different thermal and flow boundary conditions. Both the maximum cooling load that can be removed by displacement ventilation and the ventilation effectiveness are shown to depend on the heat source type and ventilation rate in a room.

Yuan, X.; Chen, Q.; Glicksman, L.R.

1999-07-01

204

ISOLATION-PERFUSION OF OVINE HIND LIMBS. III. PERFUSATE LYSINE LEVELS 1  

Microsoft Academic Search

SUMMARY Fifteen wether lambs averaging 25.4 kg were utilized in a study to determine the influence of different perfusate lysine levels on amino acid metabolism in isolated-perfused ovine hind limbs. Lysine containing 50\\/~Ci of 14 C-L-lysine (UL) was added to the modified whole blood perfusate at levels equivalent to 0, 9 and 18 \\/amole of added lysine per 100 ml

J. A. Boling; J. C. Willard; W. R. Burris

205

Residual Energy and Imbalance in Solar Wind Turbulence  

NASA Astrophysics Data System (ADS)

The energy spectra of magnetic field and velocity have been well measured in inertial range solar wind turbulence. It is not well understood, however, why these spectra, on average, display different power law behavior. Here, we present new measurements of the residual energy scaling and its variation with relevant solar wind parameters. These measurements are compared to theoretical predictions to determine the cause of this difference. We also examine the local properties of both the residual energy and cross helicity in the solar wind, finding that globally balanced turbulence can consist of patches of local imbalance at all scales and that the residual energy is consistently negative at all scales. The importance of these findings for the turbulence dynamics is discussed.

Chen, C. H.; Salem, C. S.; Bale, S. D.

2012-12-01

206

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

207

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

PubMed

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

2012-04-15

208

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

209

Comparative evaluation of the effects of indomethacin and ibuprofen on cerebral perfusion and oxygenation in preterm infants with patent ductus arteriosus  

Microsoft Academic Search

Objective: To compare the effects on cerebral perfusion and oxygenation of intravenous ibuprofen and indomethacin as treatment for patent ductus arteriosus in preterm infants.Study design: Sixteen infants receiving mechanical ventilation (< 31 weeks gestation) with patent ductus arteriosus received either 0.2 mg\\/kg indomethacin ( n = 8) or 10 mg\\/kg ibuprofen ( n = 8) infused over 1 minute. Near-infrared

Fabio Mosca; Milena Bray; Maria Lattanzio; Monica Fumagalli; Camillo Tosetto

1997-01-01

210

Microcirculation Perfusion Monitor on the Back of the Health Volunteers  

PubMed Central

Objective. To observe the dermal microcirculation blood perfusion characterization of meridians channels (acupoints). Methods. 20 healthy human subjects were monitored using Pericam Perfusion Speckle Imager (PSI) for the changes in dermal microcirculation blood perfusion on governor meridian and other respective dermal regions as a control. Result. The microcirculation blood perfusion on Governor Meridian is higher than its control area. Conclusion. The dermal microcirculation blood perfusion on certain parts of Governor Meridian of healthy human subjects showed specifics. PMID:24371463

Li, Yanqi; Li, Xiaomei; Zhou, Dan; Wang, Kang; Liu, Yangyang; Guo, Yi; Qiu, Shuang; Zhai, Tianchen; Liu, Shuang; Liu, Jingjing; Ming, Dong

2013-01-01

211

Perfusion Quantification Using Gaussian Process Deconvolution  

E-print Network

using dynamic susceptibility contrast MRI (DSC-MRI) requires deconvolution to obtain the residual imaging (DSC- MRI) (1,2). The first perfusion measurements using DSC- MRI were performed by Villringer et

212

Site of pulmonary vasodilation by inhaled nitric oxide in the perfused lung  

SciTech Connect

Site of pulmonary vasodilation by inhaled nitric oxide in the perfused lung. To determine the site of inhaled nitric oxide (NO)-induced pulmonary vasodilation, a double vascular occlusion technique was used with rabbit lungs ventilated and perfused at 20 ml/min with Krebs solution containing 3% dextran and 30 {mu}M indomethacin. Inhaled NO (120 ppm for 3% min) reduced pulmonary vasoconstriction produced by U-46619 infusion (0.5 -1.2 nmol/min), significantly decreasing total resistance (RT) [1,080 {plus_minus} 51 (SE) vs. 1,545 {plus_minus} 109 mmHg-min/l; P < 0.01]. Acetylcholine infusion (ACh; 2-5 nmol/min) and nitroglycerin (NTG; 0.35 {mu}mol) likewise decreased RT. Arterial resistance (Ra) was also significantly less with inhaled NO, ACh, and NTG compared with U-46619 alone. Venous resistance (Rv), however, was unchanged. When the direction of perfusion was reversed in the lung, inhaled NO, ACh, and NTG significantly decreased RT compared with U-46619 alone, and Rv was also reduced by all three agents. After electrolysis-induced acute lung injury, inhaled NO significantly reduced both RT and Ra compared with U-46619 alone, whereas Rv was unaffected. Our results demonstrate that inhaled NO gas affects primarily the arterial (precapillary) component of the pulmonary circulation but, under conditions of extreme venous constriction, may dilate the postcapillary component as well. 25 refs., 4 figs.

Rimar, S.; Gillis, C.N. [Yale Univ. School of Medicine, New Haven, CT (United States)

1995-05-01

213

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

214

Development of a Residential Integrated Ventilation Controller  

SciTech Connect

The goal of this study was to develop a Residential Integrated Ventilation Controller (RIVEC) to reduce the energy impact of required mechanical ventilation by 20percent, maintain or improve indoor air quality and provide demand response benefits. This represents potential energy savings of about 140 GWh of electricity and 83 million therms of natural gas as well as proportional peak savings in California. The RIVEC controller is intended to meet the 2008 Title 24 requirements for residential ventilation as well as taking into account the issues of outdoor conditions, other ventilation devices (including economizers), peak demand concerns and occupant preferences. The controller is designed to manage all the residential ventilation systems that are currently available. A key innovation in this controller is the ability to implement the concept of efficacy and intermittent ventilation which allows time shifting of ventilation. Using this approach ventilation can be shifted away from times of high cost or high outdoor pollution towards times when it is cheaper and more effective. Simulations, based on the ones used to develop the new residential ventilation requirements for the California Buildings Energy code, were used to further define the specific criteria and strategies needed for the controller. These simulations provide estimates of the energy, peak power and contaminant improvement possible for different California climates for the various ventilation systems. Results from a field test of the prototype controller corroborate the predicted performance.

Staff Scientist; Walker, Iain; Sherman, Max; Dickerhoff, Darryl

2011-12-01

215

Improved exercise myocardial perfusion during lidoflazine therapy  

SciTech Connect

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

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

1983-11-01

216

Cerebral Perfusion CT: Technique and Clinical Applications  

Microsoft Academic Search

Perfusion computed tomography (PCT) is an imaging technique that allows rapid, noninvasive, quantitative evaluation of cerebral\\u000a perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The concepts\\u000a behind this imaging technique were developed in the 1980s, but its widespread clinical use was allowed by the recent introduction\\u000a of rapid, large-coverage multidetector-

Max Wintermark

217

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

218

Assessment of regional lung ventilation by electrical impedance tomography in a patient with unilateral bronchial stenosis and a history of tuberculosis*  

PubMed Central

Bronchial stenosis can impair regional lung ventilation by causing abnormal, asymmetric airflow limitation. Electrical impedance tomography (EIT) is an imaging technique that allows the assessment of regional lung ventilation and therefore complements the functional assessment of the lungs. We report the case of a patient with left unilateral bronchial stenosis and a history of tuberculosis, in whom regional lung ventilation was assessed by EIT. The EIT results were compared with those obtained by ventilation/perfusion radionuclide imaging. The patient was using nasal continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea syndrome. Therefore, we studied the effects of postural changes and of the use of nasal CPAP. The EIT revealed heterogeneous distribution of regional lung ventilation, the ventilation being higher in the right lung, and this distribution was influenced by postural changes and CPAP use. The EIT assessment of regional lung ventilation produced results similar to those obtained with the radionuclide imaging technique and had the advantage of providing a dynamic evaluation without radiation exposure. PMID:24473768

Marinho, Liégina Silveira; de Sousa, Nathalia Parente; Barros, Carlos Augusto Barbosa da Silveira; Matias, Marcelo Silveira; Monteiro, Luana Torres; Beraldo, Marcelo do Amaral; Costa, Eduardo Leite Vieira; Amato, Marcelo Britto Passos; Holanda, Marcelo Alcantara

2013-01-01

219

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

220

Efficiency Measurement of Momentum Imbalance Trigger at CMS for Supersymmetry Searches  

E-print Network

EFFICIENCY MEASUREMENT OF MOMENTUM IMBALANCE TRIGGER FOR SUPERSYMMETRY SEARCHES AT CMS AT THE LHC An Undergraduate Research Scholars Thesis by CHRISTOPHER J. DAVIS Submitted to Honors and Undergraduate Research Texas A&M University... : : : : : : : : : : : : : : : : : : : : : : : : : 28 REFERENCES : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 30 ABSTRACT E ciency Measurement of Momentum Imbalance Trigger for Supersymmetry Searches at CMS at the LHC. (May 2013) Christopher J. Davis Department...

Davis, Christopher J

2013-02-01

221

Mapping of Chromosomal Imbalances in Pancreatic Carcinoma by Comparative Genomic Hybridization1  

Microsoft Academic Search

To identify recurrent chromosomal imbalances in pancreatic adenocar- cinoma, 27 tumors were analyzed by using comparative genomic hybrid ization. In 23 cases chromosomal imbalances were found. Gains of chro mosomal material were much more frequent than losses. The most common overrepresentations were observed on chromosomes 16p (eight cases), 20q (seven cases), 22q (six cases), and 17q (five cases) and under-

Sabina Solinas-Toldo; Christine Wallrapp; Martin Bentz; Thomas Gress; Peter Lichter

222

A Study with Class Imbalance and Random Sampling for a Decision Tree  

E-print Network

. Prati, Gustavo E. A. P. A Batista, and Maria Carolina Monard Abstract Sampling methods are a direct-ended question about sampling methods is which distribution can provide the best results, if any. In this work we imbalance is present[2, 10]. Sampling methods are a direct approach to tackle the problem of class imbalance

Batista, Gustavo

223

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

224

Imbalance between neuroexcitatory and neuroinhibitory amino acids causes craving for ethanol  

Microsoft Academic Search

Long-term exposure to ethanol leads to an imbalance in different excitatory and inhibitory amino acids. When ethanol consumption is reduced or completely stopped, these imbalances in different amino acids and neurotransmitters are behaviorally expressed in the form of ethanol withdrawal. Glutamate, a major excitatory amino acid, and GABA, a major inhibitory amino acid, are responsible, at least partly, for ethanol

Philippe De Witte

2004-01-01

225

Wife Beating in South Africa: An Imbalance Theory of Resources and Power  

ERIC Educational Resources Information Center

This article develops an imbalance theory to explain physical violence against women in intimate relationships in South Africa. The theory proposes four typologies: dependence, compensation, submission, and transgression, through which imbalances in resource contribution and power distribution between spouses are hypothesized to contribute to…

Choi, Susanne Y. P.; Ting, Kwok-Fai

2008-01-01

226

Low-complexity pilot-aided compensation for carrier frequency offset and I\\/Q imbalance  

Microsoft Academic Search

We propose a novel pilot-aided compensation scheme for carrier frequency offset (CFO) and I\\/Q imbalance. The proposed scheme comprises a generalized periodic pilot and a low-complexity acquisition algorithm, where the CFO and the coefficients for I\\/Q imbalance compensation can be obtained in explicit closed-form.

Hai Lin; Xu Zhu; Katsumi Yamashita

2010-01-01

227

Earth's Energy Imbalance and Implications James Hansen, Makiko Sato, Pushker Kharecha  

E-print Network

is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar of heat energy to space. The temporary imbalance between the energy absorbed from the sun and heat1 Earth's Energy Imbalance and Implications James Hansen, Makiko Sato, Pushker Kharecha NASA

Hansen, James E.

228

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

229

Regulation of ammonia production by mouse proximal tubules perfused in vitro. Effect of luminal perfusion.  

PubMed Central

To investigate factors regulating ammonia (NH3) production by isolated defined proximal tubule segments, we examined the rates of total NH3 (NH3 + NH+4) production by individual proximal tubule segments perfused in vitro under a variety of perfusion conditions. Segments consisting of late convoluted and early straight portions of superficial proximal tubules were incubated at 37 degrees C in Krebs-Ringer bicarbonate (KRB) buffer containing 0.5 mM L-glutamine and 1.0 mM sodium acetate, pH 7.4. The rate of total ammonia production was calculated from the rate of accumulation of total NH3 in the bath. The total ammonia production rate by unperfused proximal segments was 6.0 +/- 0.2 (+/- SE) pmol/mm per minute, which was significantly lower than segments perfused at a flow rate of 22.7 +/- 3.4 nl/min with KRB buffer (21.5 +/- 1.4 pmol/mm per minute; P less than 0.001) or with KRB buffer containing 0.5 mM L-glutamine (31.9 +/- 2.5; P less than 0.001). The rate of NH3 production was higher in segments perfused with glutamine than in segments perfused without glutamine (P less than 0.01). The perfusion-associated stimulation of NH3 production was characterized further. Analysis of collected luminal fluid samples revealed that the luminal fluid total NH3 leaving the distal end of the perfused proximal segment accounted for 91% of the increment in NH3 production observed with perfusion. Increasing the perfusion flow rate from 3.7 +/- 0.1 to 22.7 +/- 3.4 nl/min by raising the perfusion pressure resulted in an increased rate of total NH3 production in the presence or absence of perfusate glutamine (mean rise in rate of total NH3 production was 14.9 +/- 3.7 pmol/mm per minute in segments perfused with glutamine and 7.8 +/- 0.9 in those perfused without glutamine). In addition, increasing the perfusion flow rate at a constant perfusion pressure increased the rate of luminal output of NH3. Total NH3 production was not affected by reducing perfusate sodium concentration to 25 mM and adding 1.0 mM amiloride to the perfusate, a condition that was shown to inhibit proximal tubule fluid reabsorption. These observations demonstrate that the rate of total NH3 production by the mouse proximal tubule is accelerated by perfusion of the lumen of the segment, by the presence of glutamine in the perfusate, and by increased perfusion flow rates. The increased rate of NH3 production with perfusion seems not to depend upon normal rates of sodium reabsorption. The mechanism underlying the stimulation of NH3 production by luminal flow is unknown and requires further study. PMID:3920246

Nagami, G T; Kurokawa, K

1985-01-01

230

Passive ventilation for residential air quality control  

Microsoft Academic Search

Infiltration has long served the residential ventilation needs in North America. In Northern Europe it has been augmented by purpose-provided natural ventilation systems--so-called passive ventilation systems--to better control moisture problems in dwellings smaller than their North American counterparts and in a generally wetter climate. The growing concern for energy consumption, and the environmental impacts associated with it, has however led

Axley

1999-01-01

231

Airway pressure release ventilation in morbidly obese surgical patients with acute lung injury and acute respiratory distress syndrome.  

PubMed

Morbidly obese patients with body mass index greater than 40 kg/m(2) and respiratory failure requiring critical care services are increasingly seen in trauma and acute care surgical centers. Baseline respiratory pathophysiology including decreased pulmonary compliance with dependent atelectasis and abnormal ventilation-perfusion relationships predisposes these patients to acute lung injury (ALI) and adult respiratory distress syndrome (ARDS) as well as prolonged stays in the intensive care unit. Airway pressure release ventilation (APRV) is an increasingly used alternative mode for salvage therapy in patients with hypoxemic respiratory failure that also provides lung protection from ventilator-induced lung injury. APRV provides the conceptual advantage of an "open lung" approach to ventilation that may be extended to the morbidly obese patient population with ALI and ARDS. We discuss the theoretical benefits and a recent clinical experience of APRV ventilation in the morbidly obese patient with respiratory failure at a Level I trauma, surgical critical care, and acute care surgery center. PMID:23461947

Testerman, George M; Breitman, Igal; Hensley, Sarah

2013-03-01

232

Efficacy of intermittent ventilation for providing acceptable indoor air quality  

Microsoft Academic Search

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

M. H. Sherman

2004-01-01

233

Brain Perfusion in Children: Evolution With Age Assessed by Quantitative Perfusion Computed Tomography  

Microsoft Academic Search

Objective. The objective of this study was to assess the age-related variations of brain perfu- sion through quantitative cerebral perfusion computed tomography (CT) results in children without brain ab- normality. Methods. Brain perfusion CT examinations were per- formed in 77 children, aged 7 days to 18 years. These patients were admitted at our institution for both non- contrast and contrast-enhanced

Max Wintermark; Domenico Lepori; Jacques Cotting; Eliane Roulet; Guy van Melle; Reto Meuli; Philippe Maeder; Luca Regli; Francis R. Verdun; Thierry Deonna; Pierre Schnyder; Francois Gudinchet

2010-01-01

234

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

235

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

236

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

237

Cardiac Angiogenic Imbalance Leads to Peri-partum Cardiomyopathy  

PubMed Central

Peri-partum cardiomyopathy (PPCM) is a frequently fatal disease that affects women near delivery, and occurs more frequently in women with pre-eclampsia and/or multiple gestation. The etiology of PPCM, or why it associates with pre-eclampsia, remains unknown. We show here that PPCM is associated with a systemic angiogenic imbalance, accentuated by pre-eclampsia. Mice that lack cardiac PGC-1?, a powerful regulator of angiogenesis, develop profound PPCM. Importantly, the PPCM is entirely rescued by pro-angiogenic therapies. In humans, the placenta in late gestation secretes VEGF inhibitors like soluble Flt1 (sFlt1), and this is accentuated by multiple gestation and pre-eclampsia. This anti-angiogenic environment is accompanied by sub-clinical cardiac dysfunction, the extent of which correlates with circulating levels of sFlt1. Exogenous sFlt1 alone caused diastolic dysfunction in wildtype mice, and profound systolic dysfunction in mice lacking cardiac PGC-1?. Finally, plasma samples from women with PPCM contained abnormally high levels of sFlt1. These data strongly suggest that PPCM is in large part a vascular disease, caused by excess anti-angiogenic signaling in the peri-partum period. The data also explain how late pregnancy poses a threat to cardiac homeostasis, and why pre-eclampsia and multiple gestation are important risk factors for the development of PPCM. PMID:22596155

Patten, Ian S.; Rana, Sarosh; Shahul, Sajid; Rowe, Glenn C; Jang, Cholsoon; Liu, Laura; Hacker, Michele R.; Rhee, Julie S.; Mitchell, John; Mahmood, Feroze; Hess, Phil; Farrell, Caitlin; Koulisis, Nicole; Khankin, Eliyahu V; Burke, Suzanne D.; Tudorache, Igor; Bauersachs, Johann; del Monte, Federica; Hilfiker-Kleiner, Denise; Karumanchi, S. Ananth; Arany, Zoltan

2012-01-01

238

Correlation between facial asymmetry, shoulder imbalance, and adolescent idiopathic scoliosis.  

PubMed

We conducted a prospective cross-sectional study to examine the correlation between facial asymmetry, shoulder imbalance, and adolescent idiopathic scoliosis. Sixty-nine adolescent idiopathic scoliosis patients and 29 healthy volunteers were enrolled in this study. All patients underwent whole-spine standing anteroposterior radiographs and frontal cephalograms. Patients were divided into mild, moderate, and severe groups depending on Cobb angle (10°-25°, 25°-40°, and >40°, respectively). Facial measurements included maxilla height difference, ramus length difference, and anterior nasal spine-menton angle. Shoulder measurements included coracoid height difference, clavicular angle, clavicle-rib intersection difference, and radiographic shoulder height.The anterior nasal spine-menton angle in the severe group (>40°) was higher than in the other groups (P<.05), as was the clavicle-rib intersection difference (P<.05). In addition, the magnitude of the curve showed a possible correlation with the anterior nasal spine-menton angle and clavicle-rib intersection difference in scoliosis patients (r=0.433 and r=0.511, respectively). According to different curve patterns, the anterior nasal spine-menton angle and clavicle-rib intersection difference were significantly higher in the double thoracic group than in the other groups (P<.05). In the correlation analysis, the ramus length difference and anterior nasal spine-menton angle had a possible correlation with the coracoid height difference, clavicular angle, radiographic shoulder height, and clavicle-rib intersection difference (P<.05). PMID:21667906

Hong, Jae-Young; Suh, Seung-Woo; Modi, Hitesh N; Yang, Jae-Hyuk; Hwang, Young-Chul; Lee, Dong-Yul; Hur, Chang-Yong; Park, Young-Hwan

2011-06-01

239

Mnesic imbalance: a cognitive theory about autism spectrum disorders  

PubMed Central

Autism is characterized by impairments in social interaction, communicative capacity and behavioral flexibility. Some cognitive theories can be useful for finding a relationship between these irregularities and the biological mechanisms that may give rise to this disorder. Among such theories are mentalizing deficit, weak central coherence and executive dysfunction, but none of them has been able to explain all three diagnostic symptoms of autism. These cognitive disorders may be related among themselves by faulty learning, since several research studies have shown that the brains of autistic individuals have abnormalities in the cerebellum, which plays a role in procedural learning. In keeping with this view, one may postulate the possibility that declarative memory replaces faulty procedural memory in some of its functions, which implies making conscious efforts in order to perform actions that are normally automatic. This may disturb cognitive development, resulting in autism symptoms. Furthermore, this mnesic imbalance is probably involved in all autism spectrum disorders. In the present work, this theory is expounded, including preliminary supporting evidence. PMID:18925971

Romero-Munguia, Miguel Angel

2008-01-01

240

Earth’s Energy Imbalance: Confirmation and Implications  

E-print Network

Our climate model, driven mainly by increasing human-made greenhouse gases and aerosols, among other forcings, calculates that Earth is now absorbing 0.85 T 0.15 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years. Implications include (i) the expectation of additional global warming of about 0.6-C without further change of atmospheric composition; (ii) the confirmation of the climate system’s lag in responding to forcings, implying the need for anticipatory actions to avoid any specified level of climate change; and (iii) the likelihood of acceleration of ice sheet disintegration and sea level rise. Earth_s climate system has considerable thermal inertia. This point is of critical importance to policy- and decision-makers who seek to mitigate the effects of undesirable anthropogenicclimatechange.Theeffectoftheinertia is to delay Earth_s response to climate forcings,

James Hansen; Larissa Nazarenko; Reto Ruedy; Makiko Sato; Josh Willis; Anthony Del Genio; Dorothy Koch; Andrew Lacis; Ken Lo; Surabi Menon; Gavin A. Schmidt; Nicholas Tausnev

2005-01-01

241

Imbalance of the Earth System in Terms of Entropy  

NASA Astrophysics Data System (ADS)

The Earth system consists of many interacting geospheres (e.g., atmosphere, hydrosphere, biosphere, lithosphere, pedosphere, cryosphere), each of which is further composed of interacting subsystems over a wide range of scales. The mainstream approach to tackle this complex system relies on earth system modeling (ESM) that is based on various conservation principles (e.g., conservation of energy, mass and momentum), breaks the Earth system into ever smaller units, and includes ever more processes. Despite the great progress over the last few decades, the bottom-up ESM approach still suffers from many deficiencies such as highly uncertain climate sensitivity and cloud feedbacks. This study explores a new theoretical framework that treats the Earth system as a whole and seeks entropy-based principles in addition to those conservation principles (e.g., energy conservation). In particular, we show that even at steady state, radiation entropy is highly imbalanced with the outgoing longwave radiation carrying much more radiation entropy than the incoming solar radiation, and that the Earth system as a whole works to maximize the radiation entropy imbalance by building close connection between incoming shortwave and outgoing longwave radiation. The entropy-based theory provides a possible explanation of why the Earth albedo varies around 0.3 during the Holocene.

Liu, Y.; Wu, W.; Wiscombe, W. J.

2012-12-01

242

Biomedical implications of heavy metals induced imbalances in redox systems.  

PubMed

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

Sharma, Bechan; Singh, Shweta; Siddiqi, Nikhat J

2014-01-01

243

Perfusion harmonic imaging of the human brain  

NASA Astrophysics Data System (ADS)

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

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

2003-05-01

244

46 CFR 154.1205 - Mechanical ventilation system: Standards.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Mechanical ventilation system: Standards. 154...Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1205 Mechanical ventilation system: Standards....

2013-10-01

245

46 CFR 154.1205 - Mechanical ventilation system: Standards.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Mechanical ventilation system: Standards. 154...Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1205 Mechanical ventilation system: Standards....

2012-10-01

246

46 CFR 154.1205 - Mechanical ventilation system: Standards.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Mechanical ventilation system: Standards. 154...Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1205 Mechanical ventilation system: Standards....

2010-10-01

247

46 CFR 154.1205 - Mechanical ventilation system: Standards.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Mechanical ventilation system: Standards. 154...Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1205 Mechanical ventilation system: Standards....

2011-10-01

248

46 CFR 108.181 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Ventilation for enclosed spaces. 108.181 Section 108.181 Shipping COAST GUARD, DEPARTMENT OF HOMELAND...EQUIPMENT Construction and Arrangement Ventilation § 108.181 Ventilation for enclosed spaces....

2010-10-01

249

21 CFR 868.5935 - External negative pressure ventilator.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false External negative pressure ventilator. 868...Therapeutic Devices § 868.5935 External negative pressure ventilator. (a) Identification. An external negative pressure ventilator...

2010-04-01

250

14 CFR 27.1187 - Ventilation and drainage.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Ventilation and drainage. 27.1187 Section 27.1187 ...Protection § 27.1187 Ventilation and drainage. Each compartment containing any...must have provision for ventilation and drainage of flammable fluids. The drainage...

2010-01-01

251

14 CFR 27.1187 - Ventilation and drainage.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Ventilation and drainage. 27.1187 Section 27.1187 ...Protection § 27.1187 Ventilation and drainage. Each compartment containing any...must have provision for ventilation and drainage of flammable fluids. The drainage...

2011-01-01

252

14 CFR 27.1187 - Ventilation and drainage.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Ventilation and drainage. 27.1187 Section 27.1187 ...Protection § 27.1187 Ventilation and drainage. Each compartment containing any...must have provision for ventilation and drainage of flammable fluids. The drainage...

2013-01-01

253

14 CFR 27.1187 - Ventilation and drainage.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Ventilation and drainage. 27.1187 Section 27.1187 ...Protection § 27.1187 Ventilation and drainage. Each compartment containing any...must have provision for ventilation and drainage of flammable fluids. The drainage...

2012-01-01

254

14 CFR 27.1187 - Ventilation and drainage.  

...2014-01-01 false Ventilation and drainage. 27.1187 Section 27.1187 ...Protection § 27.1187 Ventilation and drainage. Each compartment containing any...must have provision for ventilation and drainage of flammable fluids. The drainage...

2014-01-01

255

Mechanical ventilation in cancer patients.  

PubMed

Acute respiratory failure (ARF) in cancer patients remains a frequent and severe complication, despite the general improved outcome over the last decade. The survival of cancer patients requiring ventilatory support in Intensive Care Unit (ICU) has dramatically improved over the last years. The diagnostic approach, including an invasive strategy using fiber optic bronchoscopy or a non-invasive strategy, must be effective to identify a diagnostic, as it is a crucial prognostic factor. The use of non-invasive ventilation (NIV) instead of invasive mechanical ventilation (IMV), has contributed to decrease mortality, but NIV has to be used in appropriate situations. Indeed, NIV failure (i.e., need for IMV) is deleterious. Classical prognostic factors are not relevant anymore. The number of organ failure at admission and over the first 7 ICU days governs outcomes. Ventilatory support can thus be included in different management contexts: full code management with unlimited use of life sustaining therapies, full code management for a limited period, no-intubation decision, or the use of palliative NIV. The objectives of this review article are to summarize the modified ARF diagnostic and therapeutic management, induced by improvements in both intensive care and onco-hematologic management and recent literature data. PMID:24280820

Saillard, C; Mokart, D; Lemiale, V; Azoulay, E

2014-06-01

256

Ventilating activity at the hornet nest entrance  

Microsoft Academic Search

The aim of this paper is to provide the first complete description of ventilating activity undertaken by the Oriental hornet. At the portal of each nest of the Oriental hornet ( Vespa orientalis, Hymenoptera, Vespinae) there are worker hornets that beat their wings in synchrony with one another, during summer months and at the onset of daylight. These ventilating hornets

Ksenia Riabinin; Maria Kozhevnikov; Jacob S. Ishay

2004-01-01

257

Non-invasive ventilation and sleep  

Microsoft Academic Search

In this paper, we review the effects of nocturnal mechanical ventilation on sleep. Indeed, although non-invasive assisted ventilation during sleep has been applied extensively, the exact effects of this treatment on sleep quality have not been thoroughly studied. In patients with severe chronic obstructive pulmonary disease and severe restrictive ventilatory defects, the resulting respiratory failure is aggravated by the specific

Mónica M. González; Veronica F. Parreira; Daniel O. Rodenstein

2002-01-01

258

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

259

May 1999 LBNL -42975 ASHRAE'S RESIDENTIAL VENTILATION  

E-print Network

Committee on "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings", SPC 62.2P indoor air quality in dwellings and to set minimum standards that would allow for energy efficiency on Residential Ventilation and Acceptable Indoor Air Quality. 2 This work was supported by the Assistant

260

YMP Engineered Barrier Systems Scaled Ventilation Testing  

SciTech Connect

Yucca Mountain, approximately 100 miles northwest of Las Vegas, Nevada, has been selected as the site for the nation's first geologic repository for high level nuclear waste. The Yucca Mountain Project (YMP) is currently developing the design for the underground facilities. Ventilation is a key component of the design as a way to maintain the desired thermal conditions in the emplacement drifts prior to closure. As a means of determining the effects of continuous ventilation on heat removal from the emplacement drifts two series of scaled ventilation tests have been performed. Both test series were performed in the DOE/North Las Vegas Atlas facility. The tests provided scaled (nominally 25% of the full scale emplacement drift design) thermal and flow process data that will be used to validate YMP heat and mass transport codes. The Phase I Ventilation Test series evaluated the ability of ambient ventilation air to remove energy under varying flow and input power conditions. The Phase II Ventilation Test series evaluated the ability of pre-conditioned ventilation air to remove energy under varying flow, input temperature and moisture content, and simulated waste package input power conditions. Twenty-two distinct ventilation tests were run.

S.D. Dunn; B. Lowry; B. Walsh; J.D. Mar; C. Howard; R. Johnston; T. Williams

2002-11-22

261

New modes of assisted mechanical ventilation.  

PubMed

Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes. PMID:24507472

Suarez-Sipmann, F

2014-05-01

262

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

263

Tracheobronchomegaly in preterm infants on mechanical ventilation  

Microsoft Academic Search

Tracheobronchomegaly (TBM) was diagnosed on chest radiographs as an apparent dilatation of the trachea and main bronchi in four premature infants on prolonged mechanical ventilation for respiratory distress syndrome. In a retrospective study, the parameters of assisted ventilation, the Apgar score, the presence of conatal or later infection, and hypotension were reviewed and analyzed as factors possibly contributing to the

Ž. Zupan?i?; J. Primoži?

1995-01-01

264

Lung ventilation injures areas with discrete alveolar flooding, in a surface tension-dependent fashion.  

PubMed

With proteinaceous-liquid flooding of discrete alveoli, a model of the edema pattern in the acute respiratory distress syndrome, lung inflation over expands aerated alveoli adjacent to flooded alveoli. Theoretical considerations suggest that the overexpansion may be proportional to surface tension, T. Yet recent evidence indicates proteinaceous edema liquid may not elevate T. Thus whether the overexpansion is injurious is not known. Here, working in the isolated, perfused rat lung, we quantify fluorescence movement from the vasculature to the alveolar liquid phase as a measure of overdistension injury to the alveolar-capillary barrier. We label the perfusate with fluorescence; micropuncture a surface alveolus and instill a controlled volume of nonfluorescent liquid to obtain a micropunctured-but-aerated region (control group) or a region with discrete alveolar flooding; image the region at a constant transpulmonary pressure of 5 cmH2O; apply five ventilation cycles with a positive end-expiratory pressure of 0-20 cmH2O and tidal volume of 6 or 12 ml/kg; return the lung to a constant transpulmonary pressure of 5 cmH2O; and image for an additional 10 min. In aerated areas, ventilation is not injurious. With discrete alveolar flooding, all ventilation protocols cause sustained injury. Greater positive end-expiratory pressure or tidal volume increases injury. Furthermore, we determine T and find injury increases with T. Inclusion of either plasma proteins or Survanta in the flooding liquid does not alter T or injury. Inclusion of 2.7-10% albumin and 1% Survanta together, however, lowers T and injury. Contrary to expectation, albumin inclusion in our model facilitates exogenous surfactant activity. PMID:25080924

Wu, You; Kharge, Angana Banerjee; Perlman, Carrie E

2014-10-01

265

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

266

Interrupted aortic arch with retrograde subclavian perfusion.  

PubMed

Type B interrupted aortic arch results in the left subclavian artery being perfused by a patent ductus arteriosus and antegrade flow is usually seen in the left subclavian artery. We describe a case of retrograde perfusion of the left subclavian artery through the circle of Willis in the presence of interrupted aortic arch type B and a restrictive patent ductus arteriosus. This is similar to subclavian steal syndrome when the perfusion pressure from the cerebral circuit is greater than that from the left subclavian artery. Early recognition of this phenomenon may alter management by indicating restriction at ductal level. This case highlights the need for a comprehensive review of both ventricular systolic function and ductal haemodynamics when retrograde flow is seen in the subclavian artery. PMID:25029884

Kang, Sok-Leng; Forsey, Jonathan; Walsh, Mark A

2014-06-01

267

Myocardial perfusion scintigraphy: the evidence  

PubMed Central

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by comparison with the numbers of revascularisations and coronary angiograms performed. Furthermore, MPS activity levels in this country fall far short of those in comparable European countries, with about half as many scans being undertaken per year. Currently, the number of MPS studies performed annually in the UK is 1,200/million population/year. We estimate the real need to be 4,000/million/year. The current average waiting time is 20 weeks and we recommend that clinically appropriate upper limits of waiting time are 6 weeks for routine studies and 1 week for urgent studies. PMID:15129710

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

2003-01-01

268

The basics of industrial ventilation design  

SciTech Connect

HVAC in the industrial environment assumes many roles from general ventilation to process related applications. Because of the variety of applications and the documentation available for the design of each, it is not the intent of this article to review each one. However, industrial clients often have misconceptions that lead to misapplications of ventilation design and equipment. One of the more common misconceptions is that ventilation equipment should be sized based on volumetric air changes, regardless of the application. This article will review a generalized approach to ventilation calculations, the fallacy of air changes, and the role of HVAC engineers to provide the industrial client a properly applied ventilation design and thorough knowledge of its operational parameters.

Parks, R.L. [McKim and Creed, Raleigh, NC (United States)

1996-11-01

269

An intelligent control system for ventilators.  

PubMed

This study reports on a ventilator system that consists of several intelligent modules for controlling ventilator operation. These modules are software programs in two controllers. One controller is a personal computer used for diagnoses, determining settings and checking the effects of settings. The other controller is a single-chip microprocessor in a ventilator that controls the ventilator's settings in accordance with the computer settings. After setting up the system, an artificial lung model simulating a patient's lung is used to test the system. The result of test run indicated that it always responds to a patient's lung condition in a stable manner. Thus, the proposed system with its intelligent modules may assist clinicians in caring for patients and managing ventilator operation. PMID:9832029

Wang, C S; Shaw, D; Jih, K S

1998-10-01

270

Pandemic Ventilator Rationing and Appeals Processes  

PubMed Central

In a severe influenza pandemic, hospitals will likely experience serious and widespread shortages of patient pulmonary ventilators and of staff qualified to operate them. Deciding who will receive access to mechanical ventilation will often determine who lives and who dies. This prospect raises an important question whether pandemic preparedness plans should include some process by which individuals affected by ventilator rationing would have the opportunity to appeal adverse decisions. However, the issue of appeals processes to ventilator rationing decisions has been largely neglected in state pandemic planning efforts. If we are to devise just and effective plans for coping with a severe influenza pandemic, more attention to the issue of appeals processes for pandemic ventilator rationing decisions is needed. Arguments for and against appeals processes are considered, and some suggestions are offered to help efforts at devising more rational pandemic preparedness plans. PMID:20354793

Patrone, Daniel; Resnik, David

2014-01-01

271

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

272

Penumbral imaging by using perfusion computed tomography and perfusion-weighted magnetic resonance imaging: current concepts.  

PubMed

Perfusion computed tomography and perfusion-weighted magnetic resonance imaging are used to evaluate the extent of the area with ischemic penumbra; however, different parameters, algorithms, and software packages show significant discrepancies in the size of perfusion abnormalities, which should be minimized. Recently, cross-validation studies were performed using digital phantoms and have elucidated the precision and reliability of various penumbral imaging techniques. These research initiatives can promote further multicenter trials on recanalization therapies by providing accurate inclusion/exclusion criteria for appropriate patient selection. PMID:23153549

Sasaki, Makoto; Kudo, Kohsuke; Christensen, Soren; Yamashita, Fumio; Goodwin, Jonathan; Higuchi, Satomi; Ogawa, Akira

2013-11-01

273

Diagnosis of nutrient imbalances with vector analysis in agroforestry systems.  

PubMed

Agricultural intensification has had unintended environmental consequences, including increased nutrient leaching and surface runoff and other agrarian-derived pollutants. Improved diagnosis of on-farm nutrient dynamics will have the advantage of increasing yields and will diminish financial and environmental costs. To achieve this, a management support system that allows for site-specific rapid evaluation of nutrient production imbalances and subsequent management prescriptions is needed for agroecological design. Vector diagnosis, a bivariate model to depict changes in yield and nutritional response simultaneously in a single graph, facilitates identification of nutritional status such as growth dilution, deficiency, sufficiency, luxury uptake, and toxicity. Quantitative data from cocoa agroforestry systems and pigeonpea intercropping trials in Ghana and Tanzania, respectively, were re-evaluated with vector analysis. Relative to monoculture, biomass increase in cocoa ( L.) under shade (35-80%) was accompanied by a 17 to 25% decline in P concentration, the most limiting nutrient on this site. Similarly, increasing biomass with declining P concentrations was noted for pigeonpea [ (L). Millsp.] in response to soil moisture availability under intercropping. Although vector analysis depicted nutrient responses, the current vector model does not consider non-nutrient resource effects on growth, such as ameliorated light and soil moisture, which were particularly active in these systems. We revisit and develop vector analysis into a framework for diagnosing nutrient and non-nutrient interactions in agroforestry systems. Such a diagnostic technique advances management decision-making by increasing nutrient precision and reducing environmental issues associated with agrarian-derived soil contamination. PMID:21546672

Isaac, Marney E; Kimaro, Anthony A

2011-01-01

274

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

275

[Lung perfusion scintigraphy in pediatric patients with congenital malformations].  

PubMed

Congenital malformations are an heterogeneous group of disorders that can lead changes in pulmonary perfusion and then can be evaluated with lung perfusion scintigraphy. We selected five patients in which the role of lung perfusion scintigraphy emerges as a reliable and non-invasive imaging technique. Lung perfusion scintigraphy is a useful tool in pediatric patients with congenital malformations allowing an accurate evaluation of the best therapeutic strategy and its results. PMID:24042425

Niccoli Asabella, Artor; Stabile Ianora, Amato Antonio; Di Palo, Alessandra; Rubini, Domenico; Pisani, Antonio Rosario; Ferrari, Cristina; Notaristefano, Antonio; Rubini, Giuseppe

2013-01-01

276

Automatic Assessment of Cardiac Perfusion Hildur Olafsdottir1  

E-print Network

Appearance Mod- els (AAM) is applied for automatic registration of myocardial perfusion MRI. A semi-quantitative perfusion MRI has proven to be a powerful method to assess coronary artery diseases. The ultimate goal of the analysis is to obtain a full quantifica- tion of the perfusion in ml/(g·min), see e.g. [3]. A step towards

277

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; Dorfler, Arnd; Rovira, Alex; Wintermark, Max; Law, Meng

2013-01-01

278

A laser speckle imaging technique for measuring tissue perfusion  

Microsoft Academic Search

Laser Doppler imaging (LDI) has become a standard method for optical measurement of tissue perfusion, but is limited by low resolution and long measurement times. We have developed an analysis technique based on a laser speckle imaging method that generates rapid, high-resolution perfusion images. We have called it laser speckle perfusion imaging (LSPI). This paper investigates LSPI output and compares

Kevin R. Forrester; J. Tulip; C. Leonard; C. Stewart; Robert C. Bray

2004-01-01

279

Cerebral perfusion defects in combined cocaine and alcohol dependence  

Microsoft Academic Search

Background: Cocaine abuse has been associated with widely distributed areas of significant cerebral blood flow (CBF) reductions or hypo-perfusion as well as CBF hyper-perfusion, but these perfusion abnormalities have not been examined using newer technologies such as statistical parametric mapping (SPM). These areas of abnormal CBF may be more likely among those who abuse cocaine and alcohol together. Methods: Using

P. C Gottschalk; Thomas R Kosten

2002-01-01

280

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

281

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...

282

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

283

Cytokine Imbalance in Infants Receiving Extracorporeal Membrane Oxygenation for Respiratory Failure  

Microsoft Academic Search

Background: It is likely that the imbalance between the pro- and anti-inflammatory cytokines will determine the outcome in infants with severe respiratory failure receiving extracorporeal membrane oxygenation (ECMO). Aims: We determined if there was an imbalance between pro- and anti-inflammatory cytokines in serial bronchoalveolar lavage (BAL) fluid obtained from survivors and non-survivors of ECMO. Methods: We therefore measured the cellular

Reinout J. Mildner; Nicholas Taub; Julian R. Vyas; Hillary M. Killer; Richard K. Firmin; David J. Field; Sailesh Kotecha

2005-01-01

284

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

285

Prism adaptation to rightward optical deviation improves postural imbalance in left-hemiparetic patients  

Microsoft Academic Search

Left-hemiparetic patients show predominant postural imbalance as compared to right-hemiparetic patients. The right hemisphere is crucial for generating internal maps used for perceptual and premotor processing of spatial information. Predominant postural imbalance with right-brain damage could thus result from a distortion of an internal postural map. Well-known manifestations of distorted internal maps due to right-hemisphere lesions, such as hemineglect, may

Caroline Tilikete; Gilles Rode; Yves Rossetti; Jacques Pichon; Ling Li; Dominique Boisson

2001-01-01

286

Efficient compensation of I\\/Q phase imbalance for digital receivers  

Microsoft Academic Search

In I\\/Q receivers characterized by direct conversion or low-IF operations, phase imbalance between the I and Q branches stands for a substantial issue which may degrade significantly the overall link performance. An alternative solution to high cost analog components with small tolerances which make the I\\/Q imbalance effect negligible is to estimate and compensate it digitally. In this paper we

Luca Giugno; Vincenzo Lottici; Marco Luise

2005-01-01

287

Blind Frequency-Dependent I\\/Q Imbalance Compensation Using System Identification  

Microsoft Academic Search

A novel blind frequency-dependent I\\/Q imbalance compensation for direct-conversion receivers is proposed. By analyzing the filter which represents branch mismatches, we prove its minimum phase response, for practical front-ends with reasonable image attenuation quality. We also reveal that the received branch signals will have the same autocorrelation in the absence of frequency-dependent imbalance. The proposed method is to obtain the

Hai Lin; Katsumi Yamashita

2011-01-01

288

Thermoelectric generation of charge imbalance at a superconductor-normal metal interface  

Microsoft Academic Search

The thermoelectric voltage produced across a superconductor-normal metal-superconductor (SNS) sandwich by an applied heat current has been measured in Pb-Cu-PbBi and In-Al-Sn as a function of temperature. The observed divergence of the thermoelectric voltage near Tc is attributed to a charge imbalance region decaying into the superconductor from the NS interface over the quasiparticle diffusion length ?Q*. The charge imbalance

D. J. Harlingen

1981-01-01

289

Response to power imbalance in Richard M. Emerson's theory of social exchange relations  

E-print Network

RESPONSE TO POWER IMBALANCE IN RICHARD M. EMERSON'S THEORY OF SOCIAL EXCHANGE RELATIONS A Thesis by CARL JOHN NIEDERAUER, III Submicted to the Graduace College of Texas AAM University in partial fulfillmenc of che requirements for tne degree... of MASTER OF SCIENCE May 1988 Major Subject: Sociology RESPONSE TO POWER IMBALANCE IN RICHARD M. EMERSON'S THEORT OF SOCIAL EXCHANGE RELATIONS A Thesis by CARL JOHN NIEDERAVER) III Approved as to style and content by: Jane A. Sell (Chair...

Niederauer, Carl John

2012-06-07

290

Perfusion CT in Colorectal Cancer: Comparison of Perfusion Parameters with Tumor Grade and Microvessel Density  

PubMed Central

Objective The purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC. Materials and Methods Pre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD. Results In 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD. Conclusion BF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs. However, perfusion CT is limited in distinguishing well differentiated and poorly differentiated CRCs. Pre-operative perfusion CT does not reflect the MVD of CRCs. PMID:22563293

Kim, Jin Woong; Chang, Nam Kyu; Heo, Suk Hee; Shin, Sang Soo; Lee, Jae Hyuk; Hur, Young Hoe; Kang, Heoung Keun

2012-01-01

291

[Recommendations for invasive home mechanical ventilation].  

PubMed

Due to chronic respiratory failure, a proportion of patients require long-term home ventilation therapy. The treating doctors, nurses and therapists, as well as employees of the health insurance provider, all require specialized knowledge in order to establish and monitor home ventilation. The following document represents a consensus formed by the participating specialist societies, the health insurers and their medical advisory services. The recommendations for accomplishing home mechanical ventilation are based on the "S2 Guidelines for Non-Invasive and Invasive Mechanical Ventilation for Treatment of Chronic Respiratory Failure", and provide advice about the necessary qualifications of medical and nursing practitioners working in specialised ventilation centres or in the home setting. Management of transfer, which comprises the medical, technical and organisational requirements for releasing the patient from hospital care, is of paramount importance. In outpatient care, the requirements for the recruitment of resources, monitoring of procedures, adjustment of ventilation, and frequency of check-ups are each addressed. The recommendations are supplemented by appendices which include patient transfer forms, checklists for the supply of basic resources for home ventilation, as well as a template for the letter of discharge from hospital. PMID:21294061

Randerath, W J; Kamps, N; Brambring, J; Gerhard, F; Lorenz, J; Rudolf, F; Rosseau, S; Scheumann, A; Vollmer, V; Windisch, W

2011-02-01

292

Automated sonographic evaluation of testicular perfusion  

NASA Astrophysics Data System (ADS)

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

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

2006-07-01

293

A reappraisal of retrograde cerebral perfusion  

PubMed Central

Brain protection during aortic arch surgery by perfusing cold oxygenated blood into the superior vena cava was first reported by Lemole et al. In 1990 Ueda and associates first described the routine use of continuous retrograde cerebral perfusion (RCP) in thoracic aortic surgery for the purpose of cerebral protection during the interval of obligatory interruption of anterograde cerebral flow. The beneficial effects of RCP may be its ability to sustain brain hypothermia during hypothermic circulatory arrest (HCA) and removal of embolic material from the arterial circulation of the brain. RCP can offer effective brain protection during HCA for about 40 to 60 minutes. Animal experiments revealed that RCP provided inadequate cerebral perfusion and that neurological recovery was improved with selective antegrade cerebral perfusion (ACP), however, both RCP and ACP provide comparable clinical outcomes regarding both the mortality and stroke rates by risk-adjusted and case-matched comparative study. RCP still remains a valuable adjunct for brain protection during aortic arch repair in particular pathologies and patients. PMID:23977600

2013-01-01

294

Asynchronicity of facial blood perfusion in migraine.  

PubMed

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

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

2013-01-01

295

Pravastatin attenuates hypertension, oxidative stress and angiogenic imbalance in rat model of placental ischemia-induced hypertension  

PubMed Central

Preeclampsia is a pregnancy-specific condition characterized by an imbalance of circulating angiogenic factors and new-onset hypertension. Although current treatment options are limited, recent studies suggest pravastatin may improve angiogenic profile and reduce blood pressure in preeclampsia. We hypothesized pravastatin would restore angiogenic balance and reduce mean arterial pressure (MAP) in rats with reduced utero-placental perfusion pressure (RUPP)-induced hypertension. Pravastatin was administered i.p. (1 mg/kg/day) in RUPP (RUPP+P) and normal pregnant rats (NP+P) from day 14-19 of pregnancy. On day 19, MAP was measured via catheter, conceptus data was recorded and tissues collected. MAP was increased (p<0.05) in RUPP compared to NP dams and pravastatin ameliorated this difference. Pravastatin attenuated decreased fetal weight and plasma VEGF and the RUPP-induced increased sFlt-1 when compared to NP dams. Pravastatin treatment did not improve angiogenic potential in RUPP serum and decreased (P<0.05) endothelial tube formation in NP rats. RUPP rats presented with indices of oxidative stress such as increased placental catalase activity and plasma TBARS along with decreased plasma total antioxidant capacity compared to NP controls and pravastatin attenuated these effects. MAP, fetal weight, plasma VEGF, and plasma sFlt-1 were unchanged in NP+P compared to NP controls. The present data indicate that treatment with pravastatin attenuates oxidative stress and lowers MAP in placental ischemia-induced hypertension, but may have negative effects on circulating angiogenic potential during pregnancy. Further studies are needed to determine if there are long-term deleterious effects on maternal or fetal health following pravastatin treatment during pregnancy-induced hypertension or preeclampsia. PMID:23460290

Bauer, Ashley J; Banek, Christopher T; Needham, Karen; Gillham, Haley; Capoccia, Susan; Regal, Jean F; Gilbert, Jeffrey S

2013-01-01

296

How to choose an anesthesia ventilator?  

PubMed

During the past few years, many manufacturers have developed a new generation anesthesia ventilators or anesthesia workstations with innovative technology and introduced so-called new ventilatory modes in the operating room. The aim of this article is to briefly explain how an anesthesia ventilator works, to describe the main differences between the technologies used, to describe the main criteria for evaluating technical and pneumatic performances and to list key elements not to be forgotten during the process of acquiring an anesthesia ventilator. PMID:25138358

Coisel, Y; Millot, A; Carr, J; Castagnoli, A; Pouzeratte, Y; Verzilli, D; Futier, E; Jaber, S

2014-01-01

297

Can heterogeneity in ventilation be good?  

PubMed Central

Selection of the optimal positive end-expiratory pressure (PEEP) to avoid ventilator-induced lung injury in patients under mechanical ventilation is still a matter of debate. Many methods are available, but none is considered the gold standard. In the previous issue of Critical Care, Zhao and colleagues applied a method based on electrical impedance tomography to help select the PEEP that minimized ventilation inhomogeneities. Though promising when alveolar collapse and overdistension are present, this method might be misleading in patients with normal lungs. PMID:20359315

2010-01-01

298

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

299

Diagnosis of ventilator-associated pneumonia.  

PubMed

Ventilator-associated pneumonia is a frequent complication of mechanical ventilation, and it carries a significant added mortality. Proper recognition and treatment of pneumonia are associated with improved outcome. Clinical manifestations of pneumonia, chest radiograph findings, and routine analysis of the tracheal aspirate are inadequate, alone or in combination, in diagnosing pneumonia. This article discusses the methodologies that are presently available for diagnosing pneumonia in ventilated patients. Correct use of these techniques helps the clinician to establish a diagnosis with a high degree of reliability and facilitates the rational use of antibiotic treatment. PMID:8345171

Meduri, G U

1993-06-01

300

Basic Surgical Techniques in the Göttingen Minipig: Intubation, Bladder Catheterization, Femoral Vessel Catheterization, and Transcardial Perfusion  

PubMed Central

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 infections6. Transcardial perfusion is the most effective fixation method, and yields preeminent results when preparing minipig organs for histology and histochemistry2,9. 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.com10. For extensive information about porcine anatomy we refer to Nickel et al. Vol. 1-511. 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

301

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, it is necessary to have a method for determining equivalence in terms of either ventilation or indoor air quality

302

Application of Information Technology: Enhanced Notification of Critical Ventilator Events  

Microsoft Academic Search

Mechanical ventilators are designed to generate alarms when patients become disconnected or experience other critical ventilator events. However, these alarms can blend in with other accustomed sounds of the intensive care unit. Ventilator alarms that go unnoticed for extended periods of time often result in permanent patient harm or death. We developed a system to monitor critical ventilator events through

R. Scott Evans; Kyle V. Johnson; Vrena B. Flint; Tupper Kinder; Charles R. Lyon; William L. Hawley; David K. Vawdrey; George E. Thomsen

2005-01-01

303

A Dual Closed-Loop Control System for Mechanical Ventilation  

Microsoft Academic Search

Objective. Closed-loop mechanical ventilation has the potential to provide more effective ventilatory support to patients with less complexity than conventional ventilation. The purpose of this study was to investigate the effectiveness of an automatic technique for mechanical ventilation. Methods. Two closed-loop control systems for mechanical ventilation are combined in this study. In one of the control systems several physiological data

Fleur Tehrani; Mark Rogers; Takkin Lo; Thomas Malinowski; Samuel Afuwape; Michael Lum; Brett Grundl; Michael Terry

2004-01-01

304

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

305

46 CFR 111.15-10 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

306

46 CFR 111.15-10 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...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...

2012-10-01

307

46 CFR 111.15-10 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...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...

2010-10-01

308

46 CFR 111.15-10 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...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...

2011-10-01

309

[The choice of a pediatric anesthesia ventilator].  

PubMed

The technology of anesthesia ventilators has substantially progressed during last years. The choice of a pediatric anesthesia ventilator needs to be led by multiple parameters: requirement, technical (pneumatic performance, velocity of halogenated or oxygen delivery), cost (purchase, in operation, preventive and curative maintenance), reliability, ergonomy, upgradability, and compatibility. The demonstration of the interest of pressure support mode during maintenance of spontaneous ventilation anesthesia makes this mode essential in pediatrics. In contrast, the financial impact of target controlled inhalation of halogenated has not be studied in pediatrics. Paradoxically, complex and various available technologies had not been much prospectively studied. Anesthesia ventilators performances in pediatrics need to be clarified in further clinical and bench test studies. PMID:24209991

Kern, D; Larcher, C; Cottron, N; Ait Aissa, D; Fesseau, R; Alacoque, X; Delort, F; Masquère, P; Agnès, E; Visnadi, G; Fourcade, O

2013-12-01

310

46 CFR 111.105-21 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...105-21 Section 111.105-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Hazardous Locations § 111.105-21 Ventilation. A...

2012-10-01

311

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

312

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

313

Floor-supply displacement ventilation system  

E-print Network

Research on indoor environments has received more attention recently because reports of symptoms and other health complaints related to indoor environments have been increasing. Heating, ventilating, and air-conditioning ...

Kobayashi, Nobukazu, 1967-

2001-01-01

314

14 CFR 25.831 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...occupant with an airflow containing...areas to control the temperature and quantity...flight crew to control the temperature and quantity...compartments are not required if all of...compartment temperatures within 5...ventilation controls are...

2013-01-01

315

14 CFR 25.831 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...occupant with an airflow containing...areas to control the temperature and quantity...flight crew to control the temperature and quantity...compartments are not required if all of...compartment temperatures within 5...ventilation controls are...

2012-01-01

316

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

317

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 ...

318

Dallas Ebola Patient on Ventilator, Getting Dialysis  

MedlinePLUS

... features on this page, please enable JavaScript. Dallas Ebola Patient on Ventilator, Getting Dialysis Health officials report ... Tuesday, October 7, 2014 Related MedlinePlus Pages Dialysis Ebola TUESDAY, Oct. 7, 2014 (HealthDay News) -- The first ...

319

Demand Controlled Ventilation for Improved Humidity Control  

E-print Network

Demand Controlled Ventilation for Improved Humidity Control James K. Rogers, P.E. One Blacksmith Road Chelmsford, Massachusetts ABSTRACT Recently introduced technology makes it possible to continuously monitor for humidity in numerous...Demand Controlled Ventilation for Improved Humidity Control James K. Rogers, P.E. One Blacksmith Road Chelmsford, Massachusetts ABSTRACT Recently introduced technology makes it possible to continuously monitor for humidity in numerous...

Rogers, J. K.

1996-01-01

320

Weaning of infants from non invasive ventilation.  

PubMed

Non invasive ventilation (NIV) is commonly used to treat RDS in preterm infants. Although less risky than invasive ventilation, NIV has some potential side effects and appropriate weaning is therefore desirable. However, criteria for the definition of stability prior to attempting NIV weaning as well as the best weaning strategies need to be more investigated. The aim of this review is to identify criteria and interventions that can facilitate correct weaning from NIV. PMID:24957341

Gizzi, C; Massenzi, L; Pattumelli, M G; Moretti, C; Agostino, R

2014-01-01

321

Iatrogenic pneumothorax related to mechanical ventilation  

PubMed Central

Pneumothorax is a potentially lethal complication associated with mechanical ventilation. Most of the patients with pneumothorax from mechanical ventilation have underlying lung diseases; pneumothorax is rare in intubated patients with normal lungs. Tension pneumothorax is more common in ventilated patients with prompt recognition and treatment of pneumothorax being important to minimize morbidity and mortality. Underlying lung diseases are associated with ventilator-related pneumothorax with pneumothoraces occurring most commonly during the early phase of mechanical ventilation. The diagnosis of pneumothorax in critical illness is established from the patients’ history, physical examination and radiological investigation, although the appearances of a pneumothorax on a supine radiograph may be different from the classic appearance on an erect radiograph. For this reason, ultrasonography is beneficial for excluding the diagnosis of pneumothorax. Respiration-dependent movement of the visceral pleura and lung surface with respect to the parietal pleura and chest wall can be easily visualized with transthoracic sonography given that the presence of air in the pleural space prevents sonographic visualization of visceral pleura movements. Mechanically ventilated patients with a pneumothorax require tube thoracostomy placement because of the high risk of tension pneumothorax. Small-bore catheters are now preferred in the majority of ventilated patients. Furthermore, if there are clinical signs of a tension pneumothorax, emergency needle decompression followed by tube thoracostomy is widely advocated. Patients with pneumothorax related to mechanical ventilation who have tension pneumothorax, a higher acute physiology and chronic health evaluation?II?score or PaO2/FiO2 < 200 mmHg were found to have higher mortality. PMID:24834397

Hsu, Chien-Wei; Sun, Shu-Fen

2014-01-01

322

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.

323

[Neurally adjusted ventilator assist in paediatric intensive care].  

PubMed

The adaptation of the patient's breathing to the ventilator is a constant challenge in intensive care units. The use of a neurally adjusted ventilator assist (NAVA) system is growing. This system has shown an improvement in patient-ventilator synchronisation and the comfort of patients undergoing invasive or non-invasive ventilation in paediatric intensive care units. Its benefit in reducing the duration of mechanical ventilation and the length of stayin paediatric intensive care units remains however to be proven. PMID:25174176

Didier, Capucine

2014-01-01

324

Injurious mechanical ventilation affects neuronal activation in ventilated rats  

PubMed Central

Introduction Survivors of critical illness often have significant long-term brain dysfunction, and routine clinical procedures like mechanical ventilation (MV) may affect long-term brain outcome. We aimed to investigate the effect of the increase of tidal volume (Vt) on brain activation in a rat model. Methods Male Sprague Dawley rats were randomized to three groups: 1) Basal: anesthetized unventilated animals, 2) low Vt (LVt): MV for three hours with Vt 8 ml/kg and zero positive end-expiratory pressure (ZEEP), and 3) high Vt (HVt) MV for three hours with Vt 30 ml/kg and ZEEP. We measured lung mechanics, mean arterial pressure (MAP), arterial blood gases, and plasma and lung levels of cytokines. We used immunohistochemistry to examine c-fos as a marker of neuronal activation. An additional group of spontaneously breathing rats was added to discriminate the effect of surgical procedure and anesthesia in the brain. Results After three hours on LVt, PaO2 decreased and PaCO2 increased significantly. MAP and compliance remained stable in MV groups. Systemic and pulmonary inflammation was higher in MV rats than in unventilated rats. Plasma TNF? was significantly higher in HVt than in LVt. Immunopositive cells to c-fos in the retrosplenial cortex and thalamus increased significantly in HVt rats but not in LVt or unventilated rats. Conclusions MV promoted brain activation. The intensity of the response was higher in HVt animals, suggesting an iatrogenic effect of MV on the brain. These findings suggest that this novel cross-talking mechanism between the lung and the brain should be explored in patients undergoing MV. PMID:21569477

2011-01-01

325

Dependence of ventilation image derived from 4D CT on deformable image registration and ventilation algorithms.  

PubMed

Ventilation imaging using 4D CT is a convenient and low-cost functional imaging methodology which might be of value in radiotherapy treatment planning to spare functional lung volumes. Deformable image registration (DIR) is needed to calculate ventilation imaging from 4D CT. This study investigates the dependence of calculated ventilation on DIR methods and ventilation algorithms. DIR of the normal end expiration and normal end inspiration phases of the 4D CT images was used to correlate the voxels between the two respiratory phases. Three different DIR algorithms, optical flow (OF), diffeomorphic demons (DD), and diffeomorphic morphons (DM) were retrospectively applied to ten esophagus and ten lung cancer cases with 4D CT image sets that encompassed the entire lung volume. The three ventilation extraction methods were used based on either the Jacobian, the change in volume of the voxel, or directly calculated from Hounsfield units. The ventilation calculation algorithms used are the Jacobian, ?V, and HU method. They were compared using the Dice similarity coefficient (DSC) index and Bland-Altman plots. Dependence of ventilation images on the DIR was greater for the ?V and the Jacobian methods than for the HU method. The DSC index for 20% of low-ventilation volume for ?V was 0.33 ± 0.03 (1 SD) between OF and DM, 0.44 ± 0.05 between OF and DD, and 0.51 ± 0.04 between DM and DD. The similarity comparisons for Jacobian were 0.32 ± 0.03, 0.44 ± 0.05, and 0.51 ± 0.04, respectively, and for HU they were 0.53 ± 0.03, 0.56 ± 0.03, and 0.76 ± 0.04, respectively. Dependence of extracted ventilation on the ventilation algorithm used showed good agreement between the ?V and Jacobian methods, but differed significantly for the HU method. DSC index for using OF as DIR was 0.86 ± 0.01 between ?V and Jacobian, 0.28 ± 0.04 between ?V and HU, and 0.28 ± 0.04 between Jacobian and HU, respectively. When using DM or DD as DIR, similar values were obtained when comparing the different ventilation calculation methods. The similarity values for the 20% high-ventilation volume were close to those found for the 20% low-ventilation volume. The results obtained with DSC index were confirmed when using the Bland-Altman plots for comparing the ventilation images. Our data suggest that ventilation calculated from 4D CT depends on the DIR algorithm employed. Similarities between ?V and Jacobian are higher than between ?V and HU, and Jacobian and HU. PMID:23835389

Latifi, Kujtim; Forster, Kenneth M; Hoffe, Sarah E; Dilling, Thomas J; van Elmpt, Wouter; Dekker, Andre; Zhang, Geoffrey G

2013-01-01

326

Three-dimensional perfused cell culture.  

PubMed

Compelling evidence suggests the limitation and shortcomings of the current and well established cell culture method using multi-well plates, flasks and Petri dishes. These are particularly important when cell functions are sensitive to the local microenvironment, cell-cell and cell-extracellular matrix interactions. There is a clear need for advanced cell culture systems which mimic in vivo and more physiological conditions. This review summarises and analyses recent progress in three dimensional (3D) cell culture with perfusion as the next generation cell culture tools, while excluding engineered tissue culture where three dimensional scaffold has to be used for structural support and perfusion for overcoming mass transfer control. Apart from research activities in academic community, product development in industry is also included in this review. PMID:24184152

Li, Zhaohui; Cui, Zhanfeng

2014-01-01

327

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

328

Autoregulation of plasma flow in the isolated perfused rat kidney.  

PubMed Central

1. Autoregulation of renal plasma flow, by which flow remains constant despite changes in perfusion pressure, was studied in the isolated, perfused kidney of the rat. 2. Autoregulation did not occur in preparations perfused with a protein-free medium consisting of a balanced ionic solution resembling rat plasma in which 3% polyvinylpyrrolidone replaced the plasma proteins, changes in perfusion pressure over the normal autoregulatory range 100-150 mmHg produced a corresponding and linear change in venous outflow and no consistent change in renal vascular resistance. 3. Addition of human serum (5%, v/v) to the medium restored autoregulation; changes in perfusion pressure in the range 100-150 mmHg resulted in a stable plasma flow and a linear change in renal vascular resistance. The addition of bovine serum albumin (3 g/1.) to the protein-free medium restored autoregulation to a similar degree. 4. In kidneys perfused with the protein-free medium, the sensitivity of the renal vasculature to the vasoconstrictor drugs epinephrine and angiotensin II was only 1/40 the level seen in those kidneys perfused with media containing serum or albumin. 5. The experiments show that in the isolated, perfused kidney, autoregulation of plasma flow is not dependent on the presence of the globulin, angiotensinogen, in the perfusion medium; and suggest that failure of autoregulation in kidneys perfused with a protein-free medium could be attributed to the rapid decline in the sensitivity of the vascular smooth muscle to constrictor stimuli. PMID:690860

Bullivant, M

1978-01-01

329

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

330

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

331

Parallel perfusion imaging processing using GPGPU  

PubMed Central

Background and purpose The objective of brain perfusion quantification is to generate parametric maps of relevant hemodynamic quantities such as cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) that can be used in diagnosis of acute stroke. These calculations involve deconvolution operations that can be very computationally expensive when using local Arterial Input Functions (AIF). As time is vitally important in the case of acute stroke, reducing the analysis time will reduce the number of brain cells damaged and increase the potential for recovery. Methods GPUs originated as graphics generation dedicated co-processors, but modern GPUs have evolved to become a more general processor capable of executing scientific computations. It provides a highly parallel computing environment due to its large number of computing cores and constitutes an affordable high performance computing method. In this paper, we will present the implementation of a deconvolution algorithm for brain perfusion quantification on GPGPU (General Purpose Graphics Processor Units) using the CUDA programming model. We present the serial and parallel implementations of such algorithms and the evaluation of the performance gains using GPUs. Results Our method has gained a 5.56 and 3.75 speedup for CT and MR images respectively. Conclusions It seems that using GPGPU is a desirable approach in perfusion imaging analysis, which does not harm the quality of cerebral hemodynamic maps but delivers results faster than the traditional computation. PMID:22824549

Zhu, Fan; Gonzalez, David Rodriguez; Carpenter, Trevor; Atkinson, Malcolm; Wardlaw, Joanna

2012-01-01

332

Phosphorus NMR of isolated perfused morris hepatomas  

SciTech Connect

The authors are developing techniques for the study of perfused solid tumors by NMR. Tissue-isolated solid hepatomas were grown to 1-2 cm diameter as described previously. The arterial supply was isolated and the tumors perfused (0.5 - 1.0 ml/min) in vitro at 25 C with a 15% suspension of red blood cells in Krebs-Henseliet solution. /sup 31/P-NMR spectra were acquired at 162 MHz in a specially-designed NMR probe using a solenoidal coil. Intracellular pH (monitored from the chemical shift of inorganic phosphate) and ATP levels were stable for up to 6 hrs during perfusion. During 30 min of global ischemia, ATP decreased by 75% and pH fell from 7.0 to 6.7. These changes were reversed by 1 hr reperfusion. In addition to ATP and phosphate, the spectra included a large resonance due to phosphomonoesters, as well as peaks consistent with glycerylphosphocholine, glyceryl-phosphoethanolamine, phosphocreatine, NAD, and UDPG. However, the most novel feature of the spectra was the presence of an unidentified peak in the phosphonate region (+ 16.9 ppm). The peak was not present in spectra of muscle, liver, brain, kidney, or fat tissues excised from the same animals. They are presently attempting to identify the compound that gives rise to this peak and to establish its metabolic origin.

Graham, R.A.; Meyer, R.A.; Brown, T.R.; Sauer, L.A.

1986-03-05

333

Modeling study of ventilation, IAQ and energy impacts of residential mechanical ventilation  

Microsoft Academic Search

This paper reports on a simulation study of indoor air quality, ventilation and energy impacts of several mechanical ventilation approaches in a single-family residential building. The study focused on a fictitious two-story house in Spokane, Washington and employed the multizone airflow and contaminant dispersal model CONTAM. The model of the house included a number of factors related to airflow including

Persily

1998-01-01

334

Prevention of ventilator-associated pneumonia or ventilator-associated complications: a worthy, yet challenging, goal.  

PubMed

Ventilator-associated pneumonia is a difficult diagnosis to establish in the critically ill patient because of the presence of underlying cardiopulmonary disorders (e.g., pulmonary contusion, acute respiratory distress syndrome, atelectasis) and the nonspecific radiographic and clinical signs associated with this infection. However, the escalating antimicrobial resistance of the bacterial pathogens associated with ventilator-associated pneumonia, as well as with other nosocomial infections, has created an imperative to reduce their occurrence and the unnecessary use of antibiotics. Hospital-based process improvement initiatives aimed at the prevention of ventilator-associated pneumonia, and other ventilator-associated complications, have been successfully used despite the limitations of clinical criteria for establishing the diagnosis of ventilator-associated pneumonia. Given current restrictions in hospital resources, absence of available new antimicrobial agents, and potential lack of reimbursement for patients with development of ventilator-associated pneumonia, hospitals need to develop and successfully implement programs aimed at reducing ventilator-associated pneumonia. The use of evidence-based bundles targeting ventilator-associated pneumonia seems to be a reasonable first step in addressing this important clinical problem. PMID:21946659

Kollef, Marin H

2012-01-01

335

The value of regional ventilation measurements in the prediction of postoperative pulmonary function following lobectomy  

SciTech Connect

Eleven patients, mean age 62, considered for lobectomy for lung carcinoma underwent regional quantitative ventilation/perfusion scintigraphy. Preoperative selection criteria included an FEV{sub 1} (forced expiratory volume) of 55% predicted or less, and/or an FEV{sub 1}/FVC% (forced vital capacity) of <70%. A patients underwent a complete set of pulmonary function tests including flow rates, lung volumes, diffusing capacity and blood gases. The statistical correlation between the predicted postoperative FEV{sub 1} and actual yielded an r value of 0.67 with a p value of 0.56. There was good correlation between the predicted postoperative FEV{sub 1} utilizing scintigraphy and the actual, but in several cases the predicted postoperative FEV{sub 1} was underestimated. Although the degree of underestimation is insignificant, patients may be excluded from lobectomy when their values are marginal.

LaManna, M.M.; Rambaran, N.; Mezic, E.T.; Murphy, D.M.F.; Ora-Cajulis, M. (Deborah Heart and Lung Center, Browns Mills, NJ (USA))

1990-06-01

336

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

337

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

338

Perfusion Phantom: An Efficient and Reproducible Method to Simulate Myocardial First-Pass Perfusion Measurements with Cardiovascular Magnetic Resonance  

PubMed Central

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. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. 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

2013-01-01

339

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

340

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

PubMed Central

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.

2014-01-01

341

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

342

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

343

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

344

Thermal imbalance force modelling for a GPS satellite using the finite element method  

NASA Technical Reports Server (NTRS)

Methods of analyzing the perturbation due to thermal radiation and determining its effects on the orbits of GPS satellites are presented, with emphasis on the FEM technique to calculate satellite solar panel temperatures which are used to determine the magnitude and direction of the thermal imbalance force. Although this force may not be responsible for all of the force mismodeling, conditions may work in combination with the thermal imbalance force to produce such accelerations on the order of 1.e-9 m/sq s. If submeter accurate orbits and centimeter-level accuracy for geophysical applications are desired, a time-dependent model of the thermal imbalance force should be used, especially when satellites are eclipsing, where the observed errors are larger than for satellites in noneclipsing orbits.

Vigue, Yvonne; Schutz, Bob E.

1991-01-01

345

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

346

Distinct evolutionary mechanisms for genomic imbalances in high-risk and low-risk neuroblastomas  

PubMed Central

Background Neuroblastoma (NB) is the most common extracranial solid tumour of childhood. Several genomic imbalances correlate to prognosis in NB, with structural rearrangements, including gene amplification, in a near-diploid setting typically signifying high-risk tumours and numerical changes in a near-triploid setting signifying low-risk tumours. Little is known about the temporal sequence in which these imbalances occur during the carcinogenic process. Methods We have reconstructed the appearance of cytogenetic imbalances in 270 NBs by first grouping tumours and imbalances through principal component analysis and then using the number of imbalances in each tumour as an indicator of evolutionary progression. Results Tumours clustered in four sub-groups, dominated respectively by (1) gene amplification in double minute chromosomes and few other aberrations, (2) gene amplification and loss of 1p sequences, (3) loss of 1p and other structural aberrations including gain of 17q, and (4) whole-chromosome gains and losses. Temporal analysis showed that the structural changes in groups 1–3 were acquired in a step-wise fashion, with loss of 1p sequences and the emergence of double minute chromosomes as the earliest cytogenetic events. In contrast, the gains and losses of whole chromosomes in group 4 occurred through multiple simultaneous events leading to a near-triploid chromosome number. Conclusion The finding of different temporal patterns for the acquisition of genomic imbalances in high-risk and low-risk NBs lends strong support to the hypothesis that these tumours are biologically diverse entities, evolving through distinct genetic mechanisms. PMID:17897457

Gisselsson, David; Lundberg, Gisela; ?ra, Ingrid; Hoglund, Mattias

2007-01-01

347

Perfusion MRI: The Five Most Frequently Asked Technical Questions  

PubMed Central

OBJECTIVE This and its companion article address the 10 most frequently asked questions that radiologists face when planning, performing, processing, and interpreting different MR perfusion studies in CNS imaging. CONCLUSION Perfusion MRI is a promising tool in assessing stroke, brain tumors, and patients with 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:23255738

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

2013-01-01

348

Postural changes in perfusion pressure and retinal arteriolar calibre.  

PubMed Central

Ophthalmic artery perfusion pressures and retinal arteriolar calibres were studied in 10 human subjects when sitting, standing, and lying. Differing responses in perfusion pressure were found; autoregulatory responses were found in 13 of the 18 significant calibre changes on moving from sitting to standing and 13 of 22 significant calibre changes on moving from standing to lying. The remaining significant calibre changes were non-autoregulatory, the arterioles dilating with perfusion pressure increase and constricting with decrease. Images PMID:3378020

Hague, S.; Hill, D. W.

1988-01-01

349

Perfusion Scintigraphy and Patient Selection for Lung Volume Reduction Surgery  

PubMed Central

Rationale: It is unclear if lung perfusion can predict response to lung volume reduction surgery (LVRS). Objectives: To study the role of perfusion scintigraphy in patient selection for LVRS. Methods: We performed an intention-to-treat analysis of 1,045 of 1,218 patients enrolled in the National Emphysema Treatment Trial who were non–high risk for LVRS and had complete perfusion scintigraphy results at baseline. The median follow-up was 6.0 years. Patients were classified as having upper or non–upper lobe–predominant emphysema on visual examination of the chest computed tomography and high or low exercise capacity on cardiopulmonary exercise testing at baseline. Low upper zone perfusion was defined as less than 20% of total lung perfusion distributed to the upper third of both lungs as measured on perfusion scintigraphy. Measurements and Main Results: Among 284 of 1,045 patients with upper lobe–predominant emphysema and low exercise capacity at baseline, the 202 with low upper zone perfusion had lower mortality with LVRS versus medical management (risk ratio [RR], 0.56; P = 0.008) unlike the remaining 82 with high perfusion where mortality was unchanged (RR, 0.97; P = 0.62). Similarly, among 404 of 1,045 patients with upper lobe–predominant emphysema and high exercise capacity, the 278 with low upper zone perfusion had lower mortality with LVRS (RR, 0.70; P = 0.02) unlike the remaining 126 with high perfusion (RR, 1.05; P = 1.00). Among the 357 patients with non–upper lobe–predominant emphysema (75 with low and 282 with high exercise capacity) there was no improvement in survival with LVRS and measurement of upper zone perfusion did not contribute new prognostic information. Conclusions: Compared with optimal medical management, LVRS reduces mortality in patients with upper lobe–predominant emphysema when there is low rather than high perfusion to the upper lung. PMID:20538961

Chandra, Divay; Lipson, David A.; Hoffman, Eric A.; Hansen-Flaschen, John; Sciurba, Frank C.; DeCamp, Malcolm M.; Reilly, John J.; Washko, George R.

2010-01-01

350

Comparison of different mechanical ventilators for patients with poliomyelitis.  

PubMed

Poliomyelitis can affect patients with severe hypoxia and hypercapnia. Historically, most of these patients were supported by mechanical ventilation via tracheostomy. However, this procedure can lead to serious complications. Subsequently, non-invasive alternative procedures have been introduced that provide mechanical respiratory support; these include negative pressure ventilators and positive pressure ventilation via a nasal, oral, and oronasal interface. Although these ventilators are effective, various limitations have been noted. The strapless oronasal interface positive pressure ventilator appears to have the fewest limitations, and through the use of advanced dental techniques and improved dental materials, this ventilator is easily fabricated and has been noted by patients to be more comfortable. PMID:7659227

Choi, J W; Saunders, T R; Tebrock, O; Hansen, N A

1995-06-01

351

The effect of teeth-on-stator labyrinth seals on rotor imbalance response  

E-print Network

THE EFFECT OF TEETH-ON-STATOR LABYRINTH SEALS ON ROTOR IMBALANCE RESPONSE A Thesis by EILEEN MARIE CONWAY Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1991 Major Subject: Mechanical Engineering THE EFFECT OF TEETH-ON-STATOR LABYRINTH SEALS ON ROTOR IMBALANCE RESPONSE A Thesis by EILEEN MARIE CONWAY Approved as to style and content by: J1 I John M. Vance (Chair of Comminee...

Conway, Eileen Marie

2012-06-07

352

Electron-hole imbalance and large thermoelectric effect in superconducting hybrids with spin-active interfaces  

NASA Astrophysics Data System (ADS)

We argue that spin-sensitive quasiparticle scattering may generate electron-hole imbalance in superconducting structures, such as, e.g., superconducting-normal hybrids with spin-active interfaces. We elucidate a transparent physical mechanism for this effect demonstrating that scattering rates for electrons and holes at such interfaces differ from each other. Explicitly evaluating the wave functions of electronlike and holelike excitations in superconducting-normal bilayers we derive a general expression for the thermoelectric current and show that—in the presence of electron-hole imbalance—this current can reach maximum values as high as the critical current of a superconductor.

Kalenkov, Mikhail S.; Zaikin, Andrei D.

2014-10-01

353

CT perfusion of the liver: principles and applications in oncology.  

PubMed

With the introduction of molecularly targeted chemotherapeutics, there is an increasing need for defining new response criteria for therapeutic success because use of morphologic imaging alone may not fully assess tumor response. Computed tomographic (CT) perfusion imaging of the liver provides functional information about the microcirculation of normal parenchyma and focal liver lesions and is a promising technique for assessing the efficacy of various anticancer treatments. CT perfusion also shows promising results for diagnosing primary or metastatic tumors, for predicting early response to anticancer treatments, and for monitoring tumor recurrence after therapy. Many of the limitations of early CT perfusion studies performed in the liver, such as limited coverage, motion artifacts, and high radiation dose of CT, are being addressed by recent technical advances. These include a wide area detector with or without volumetric spiral or shuttle modes, motion correction algorithms, and new CT reconstruction technologies such as iterative algorithms. Although several issues related to perfusion imaging-such as paucity of large multicenter trials, limited accessibility of perfusion software, and lack of standardization in methods-remain unsolved, CT perfusion has now reached technical maturity, allowing for its use in assessing tumor vascularity in larger-scale prospective clinical trials. In this review, basic principles, current acquisition protocols, and pharmacokinetic models used for CT perfusion imaging of the liver are described. Various oncologic applications of CT perfusion of the liver are discussed and current challenges, as well as possible solutions, for CT perfusion are presented. PMID:25058132

Kim, Se Hyung; Kamaya, Aya; Willmann, Jürgen K

2014-08-01

354

New imaging technology: measurement of myocardial perfusion by contrast echocardiography  

NASA Technical Reports Server (NTRS)

Myocardial perfusion imaging has long been a goal for the non-invasive echocardiographic assessment of the heart. However, many factors at play in perfusion imaging have made this goal elusive. Harmonic imaging and triggered imaging with newer contrast agents have made myocardial perfusion imaging potentially practical in the very near future. The application of indicator dilution theory to the coronary circulation and bubble contrast agents is fraught with complexities and sources of error. Therefore, quantification of myocardial perfusion by non-invasive echocardiographic imaging requires further investigation in order to make this technique clinically viable.

Rubin, D. N.; Thomas, J. D.

2000-01-01

355

Meeting the oxygen requirements of an isolated perfused rat liver  

E-print Network

Liver perfusion systems can be used as organ culture platforms for metabolic, genetic and systems engineering, tissue regeneration, pharmacokinetics, organ storage and marginal donor reconditioning for transplantation. The ...

Izamis, Maria-Louisa, 1979-

2006-01-01

356

Tomographic Digital Subtraction Angiography for Lung Perfusion Estimation in Rodents  

E-print Network

subtraction angiography (DSA) by providing three- dimensional spatial information using tomosynthesis to therapeutics. Keywords X-ray; digital subtraction angiography; tomosynthesis; small animal; lung; perfusion

357

Pulmonary ventilation teaching aid: part 2  

NSDL National Science Digital Library

Since writing the article titled "Pulmonary ventilation teaching aid" (Stockert B, Adv Physiol Educ 27: 41ÃÂ42, 2003), we have continued to use the salad tongs and rubber band model to teach ventilation mechanics and several clinical correlates. The original article dealt primarily with normal ventilation mechanics and changes in the lungs, i.e., the rubber bands, that occur with common pulmonary disorders, e.g., pulmonary fibrosis and chronic obstructive pulmonary disease. We have developed several additional clinical correlates related to changes in the chest wall, i.e., the salad tongs. Those clinical examples are presented here. The materials needed for this demonstration are several rubber bands and a pair of metal salad tongs with a hinge.

PhD Brad Stockert (University of the Pacific Department of Physical Therapy)

2003-06-01

358

Home Mechanical Ventilation in South Korea  

PubMed Central

Purpose To survey the use of invasive and noninvasive home mechanical ventilation (HMV) methods in South Korea from the perspective of physical medicine and rehabilitation (PM&R). Materials and Methods For 413 users of HMV, retrospective reviews of PM&R interventions and survey of HMV methods employed from Mar 2000 to Dec 2009. Results Of the 413 users, the majority of whom with progressive neuromuscular disorders (NMDs) (n=358), 284 patients initially used noninvasive mechanical ventilation (NIV), while 63 others who were using tracheostomy mechanical ventilation switched to NIV as part of their rehabilitation. The NMD patients began HMV at an earlier age (34.9±20.3 yrs), and used for longer (14.7±7.5) hours than patients with non-neuromuscular causes of respiratory impairment. Conclusion Noninvasive management was preferred over invasive ones, and transition to the former was a result of PM&R interventions. PMID:25323913

Kim, Dong Hyun; Choi, Won Ah

2014-01-01

359

Elective ventilation of potential organ donors.  

PubMed

Elective ventilation describes the procedure of transferring selected patients dying from rapidly progressive intracranial haemorrhage from general medical wards to intensive care units for a brief period of ventilation before confirmation of brain stem death and harvesting of organs. This approach in Exeter has led to a rate of kidney retrieval and transplant higher than has been achieved elsewhere in the United Kingdom, with a stabilisation of numbers on patients on dialysis. Recently doubt has been cast on the legality of our practice of elective ventilation on the grounds that relatives are not permitted to consent to treatment of an incompetent person when that treatment is not in the patient's best interests. We are thus faced with the dilemma of a protocol that is ethical, practical, and operates for the greater good but which may be illegal. This article explores various objections to the protocol and calls for public, medical, and legal debate on the issues. PMID:7711541

Riad, H; Nicholls, A; Neuberger, J; Willatts, S M; Sells, R A; Jones, M A; Francis, R

1995-03-18

360

Elective ventilation of potential organ donors.  

PubMed Central

Elective ventilation describes the procedure of transferring selected patients dying from rapidly progressive intracranial haemorrhage from general medical wards to intensive care units for a brief period of ventilation before confirmation of brain stem death and harvesting of organs. This approach in Exeter has led to a rate of kidney retrieval and transplant higher than has been achieved elsewhere in the United Kingdom, with a stabilisation of numbers on patients on dialysis. Recently doubt has been cast on the legality of our practice of elective ventilation on the grounds that relatives are not permitted to consent to treatment of an incompetent person when that treatment is not in the patient's best interests. We are thus faced with the dilemma of a protocol that is ethical, practical, and operates for the greater good but which may be illegal. This article explores various objections to the protocol and calls for public, medical, and legal debate on the issues. PMID:7711541

Riad, H.; Nicholls, A.; Neuberger, J.; Willatts, S. M.; Sells, R. A.; Jones, M. A.; Francis, R.

1995-01-01

361

Perfusion fluids used in neurosurgery affect cerebrospinal fluid and surrounding brain parenchyma in the rat ventriculocisternal perfusion model.  

PubMed

ARTCEREB, an irrigation and perfusion solution (Artcereb), is a preparation intended for the irrigation and perfusion of the cerebral ventricles, and it is therefore important to evaluate its effects on cerebrospinal fluid (CSF) and on the surrounding cerebrospinal parenchyma. To confirm the kinetics of the perfusion fluid component, we performed whole body autoradiography and examined glucose balance during ventriculocisternal perfusion with (14)C-glucose labeled Artcereb in the rat model, which simulates ventricular irrigation or ventriculocisternal perfusion in clinical neurosurgery. We also performed ventriculocisternal perfusion with Artcereb, lactated Ringer's solution, or normal saline, and observed the effect of these solutions on animal condition and on brain tissue morphology. In the kinetic study, diffusion of (14)C-glucose from the perfused Artcereb to the cerebrospinal tissue was seen on whole body autoradiography, and almost 90% of the glucose in the perfusion fluid was distributed to the cerebrospinal tissue and the systemic circulation. These data indicated that the perfusion fluid interacted actively with the CSF, surrounding parenchyma and the systemic circulation, and suggested that the formation of perfusion fluid affected CSF composition and cerebrospinal tissue functions. Animals perfused with normal saline were associated with serious symptoms including tonic convulsions and death, and exhibited neuronal death in the cerebrum. However, these severe changes were not observed in animals perfused with Artcereb or lactated Ringer's solution. We therefore propose that during neurosurgery, it is extremely important to use a physiological solution like Artcereb which closely resembles normal human CSF, in order to maintain cerebrospinal function and to alleviate postoperative adverse events. PMID:19797859

Doi, Kazuhisa; Morioka, Yujiro; Nishimura, Masuhiro; Kawano, Takeshi; Harada, Daisuke; Naito, Shinsaku; Yamauchi, Aiko

2009-10-01

362

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

363

Factors Predicting Ventilator Dependence in Patients with Ventilator-Associated Pneumonia  

PubMed Central

Objectives. To determine risk factors associated with ventilator dependence in patients with ventilator-associated pneumonia (VAP). Study Design. A retrospective study was conducted at Chang Gung Memorial Hospital, Kaohsiung, from January 1, 2007 to January 31, 2008. Methods. This study evaluated 163 adult patients (aged ?18 years). Eligibility was evaluated according to the criterion for VAP, Sequential Organ Failure Assessment (SOFA) score, Acute Physiological Assessment and Chronic Health Evaluation II (APACHE II) score. Oxygenation index, underlying comorbidities, septic shock status, previous tracheostomy status, and factors related to pneumonia were collected for analysis. Results. Of the 163 VAP patients in the study, 90 patients survived, yielding a mortality rate of 44.8%. Among the 90 surviving patients, only 36 (40%) had been weaned off ventilators at the time of discharge. Multivariate logistic regression analysis was used to identify underlying factors such as congestive cardiac failure (P = 0.009), initial high oxygenation index value (P = 0.04), increased SOFA scores (P = 0.01), and increased APACHE II scores (P = 0.02) as independent predictors of ventilator dependence. Results from the Kaplan-Meier method indicate that initial therapy with antibiotics could increase the ventilator weaning rate (log Rank test, P < 0.001). Conclusions. Preexisting cardiopulmonary function, high APACHE II and SOFA scores, and high oxygenation index were the strongest predictors of ventilator dependence. Initial empiric antibiotic treatment can improve ventilator weaning rates at the time of discharge. PMID:22919335

Tseng, Chia-Cheng; Huang, Kuo-Tung; Chen, Yung-Che; Wang, Chin-Chou; Liu, Shih-Feng; Tu, Mei-Lien; Chung, Yu-Hsiu; Fang, Wen-Feng; Lin, Meng-Chih

2012-01-01

364

Open circuit mouthpiece ventilation: Concise clinical review.  

PubMed

In 2013 new "mouthpiece ventilation" modes are being introduced to commercially available portable ventilators. Despite this, there is little knowledge of how to use noninvasive intermittent positive pressure ventilation (NIV) as opposed to bi-level positive airway pressure (PAP) and both have almost exclusively been reported to have been used via nasal or oro-nasal interfaces rather than via a simple mouthpiece. Non-invasive ventilation is often reported as failing because of airway secretion encumbrance, because of hypercapnia due to inadequate bi-level PAP settings, or poor interface tolerance. The latter can be caused by factors such as excessive pressure on the face from poor fit, excessive oral air leak, anxiety, claustrophobia, and patient-ventilator dys-synchrony. Thus, the interface plays a crucial role in tolerance and effectiveness. Interfaces that cover the nose and/or nose and mouth (oro-nasal) are the most commonly used but are more likely to cause skin breakdown and claustrophobia. Most associated drawbacks can be avoided by using mouthpiece NIV. Open-circuit mouthpiece NIV is being used by large populations in some centers for daytime ventilatory support and complements nocturnal NIV via "mask" interfaces for nocturnal ventilatory support. Mouthpiece NIV is also being used for sleep with the mouthpiece fixed in place by a lip-covering flange. Small 15 and 22mm angled mouthpieces and straw-type mouthpieces are the most commonly used. NIV via mouthpiece is being used as an effective alternative to ventilatory support via tracheostomy tube (TMV) and is associated with a reduced risk of pneumonias and other respiratory complications. Its use facilitates "air-stacking" to improve cough, speech, and pulmonary compliance, all of which better maintain quality of life for patients with neuromuscular diseases (NMDs) than the invasive alternatives. Considering these benefits and the new availability of mouthpiece ventilator modes, wider knowledge of this technique is now warranted. This review highlights the indications, techniques, advantages and disadvantages of mouthpiece NIV. PMID:24841239

Garuti, G; Nicolini, A; Grecchi, B; Lusuardi, M; Winck, J C; Bach, J R

2014-01-01

365

Bronchiolectasis-a complication of artificial ventilation.  

PubMed Central

Pulmonary barotrauma associated with artificial ventilation is recognised clinically as pneumothorax, pneumo-mediastinum, or subcutaneous emphysema. Eleven patients who died in the intensive therapy unit after artificial ventilation were found at necropsy to have pronounced bronchiolectasis, which was associated with a greatly increased physiological dead space during life. The condition was best predicted by the maximum level of positive end expiratory pressure and the duration of application of positive end expiratory pressure. The clinical course of the lesion in survivors is not known. Further detailed studies are needed, but it is suggested that high levels of positive end expiratory pressure should be used with caution. Images FIG 1 FIG 2 PMID:6811071

Slavin, G; Nunn, J F; Crow, J; Dore, C J

1982-01-01

366

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

E-print Network

of Medicine, Pisa, Italy; 4 Departments of Surgery and 5 Medicine, Turku University Hospital, Turku, Finland: Liver [15 O]H2O-PET images were obtained in 14 pigs during fasting or hyperinsulinemia. Carotid arterial and liver perfusion. Endogenous glucose production (EGP) and insulin-mediated whole body glucose uptake (wb

Paris-Sud XI, Université de

367

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

E-print Network

Computed tomography perfusion (CTP) is an important functional imaging modality in the evaluation of cerebrovascular dis- eases, particularly in acute stroke and vasospasm. However, the post-processed parametric improve the differentiation between normal and ischemic tissue in the brain. Keywords: Computed tomography

Chen, Tsuhan

368

Phenylephrine to Treat Hypoxemia during One-Lung Ventilation in a Pediatric Patient  

PubMed Central

To improve surgical visualization and facilitate the procedure, one-lung ventilation (OLV) is frequently used during thoracic surgery. Although generally well tolerated, the ventilation–perfusion inequality induced by OLV may lead to a decrease in oxygenation and, at times, hypoxemia. Effective treatment algorithms and strategies are necessary for the treatment of hypoxemia during OLV to ensure that the technique can be continued without interruption and allow for completion of the surgical procedure. Treatment strategies may include applying positive end expiratory pressure to the nonoperative lung, continuous positive airway pressure or low flow oxygen insufflation to the operative lung, decreasing anesthetic agents that interfere with hypoxic pulmonary vasoconstriction (HPV), or switching to total intravenous anesthesia. Although less commonly employed, ?-adrenergic agonists may also improve oxygenation during OLV by augmenting HPV. We present a 12-year-old girl who developed hypoxemia during OLV, which was not corrected by the usual maneuvers. Hypoxemia was successfully treated with a phenylephrine infusion. The potential applications of ?-adrenergic agonists such as phenylephrine in the treatment of hypoxemia during OLV are discussed and its physiologic basis reviewed. PMID:25360404

Schloss, Brian; Martin, David; Beebe, Allan; Klamar, Jan; Tobias, Joseph D.

2013-01-01

369

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

370

Subject–ventilator synchrony during neural versus pneumatically triggered non-invasive helmet ventilation  

Microsoft Academic Search

Objective  Patient–ventilator synchrony during non-invasive pressure support ventilation with the helmet device is often compromised\\u000a when conventional pneumatic triggering and cycling-off were used. A possible solution to this shortcoming is to replace the\\u000a pneumatic triggering with neural triggering and cycling-off—using the diaphragm electrical activity (EAdi). This signal is insensitive to leaks and to the compliance of the ventilator circuit.\\u000a \\u000a \\u000a \\u000a Design  Randomized, single-blinded,

Onnen Moerer; Jennifer Beck; Lukas Brander; Roberta Costa; Michael Quintel; Arthur S. Slutsky; Fabrice Brunet; Christer Sinderby

2008-01-01

371

Experimental glomerulonephritis in the isolated perfused rat kidney.  

PubMed

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

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

1978-12-01

372

Modeling buoyancy-driven airflow in ventilation shafts  

E-print Network

Naturally ventilated buildings can significantly reduce the required energy for cooling and ventilating buildings by drawing in outdoor air using non-mechanical forces. Buoyancy-driven systems are common in naturally ...

Ray, Stephen D. (Stephen Douglas)

2012-01-01

373

24 CFR 3280.103 - Light and ventilation.  

...ventilation capacity must be provided by a mechanical system or a combination passive and mechanical system. The ventilation system or provisions...pressure condition in Uo Value Zone 1. Mechanical systems must be balanced....

2014-04-01

374

30 CFR 77.1106 - Battery-charging stations; ventilation.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 2010-07-01 false Battery-charging stations; ventilation. 77...COAL MINES Fire Protection § 77.1106 Battery-charging stations; ventilation. Battery-charging stations shall be located in...

2010-07-01

375

30 CFR 77.1106 - Battery-charging stations; ventilation.  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 2011-07-01 false Battery-charging stations; ventilation. 77...COAL MINES Fire Protection § 77.1106 Battery-charging stations; ventilation. Battery-charging stations shall be located in...

2011-07-01

376

30 CFR 77.1106 - Battery-charging stations; ventilation.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 2012-07-01 false Battery-charging stations; ventilation. 77...COAL MINES Fire Protection § 77.1106 Battery-charging stations; ventilation. Battery-charging stations shall be located in...

2012-07-01

377

30 CFR 77.1106 - Battery-charging stations; ventilation.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 2013-07-01 false Battery-charging stations; ventilation. 77...COAL MINES Fire Protection § 77.1106 Battery-charging stations; ventilation. Battery-charging stations shall be located in...

2013-07-01

378

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

379

VENTILATION RESEARCH: A REVIEW OF RECENT INDOOR AIR QUALITY LITERATURE  

EPA Science Inventory

The report gives results of a literature review, conducted to survey and summarize recent and ongoing engineering research into building ventilation, air exchange rate, pollutant distribution and dispersion, and other effects of heating, ventilation, and air-conditioning (HVAC) s...

380

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

381

46 CFR 169.315 - Ventilation (other than machinery spaces).  

Code of Federal Regulations, 2011 CFR

...manner suitable for the purpose of the space. (b) A means must be provided...vents and ventilators. (c) Living spaces must be ventilated by a mechanical...vessel's design waterline length times its maximum beam. Living...

2011-10-01

382

46 CFR 169.315 - Ventilation (other than machinery spaces).  

Code of Federal Regulations, 2012 CFR

...manner suitable for the purpose of the space. (b) A means must be provided...vents and ventilators. (c) Living spaces must be ventilated by a mechanical...vessel's design waterline length times its maximum beam. Living...

2012-10-01

383

46 CFR 169.315 - Ventilation (other than machinery spaces).  

Code of Federal Regulations, 2013 CFR

...manner suitable for the purpose of the space. (b) A means must be provided...vents and ventilators. (c) Living spaces must be ventilated by a mechanical...vessel's design waterline length times its maximum beam. Living...

2013-10-01

384

46 CFR 169.315 - Ventilation (other than machinery spaces).  

Code of Federal Regulations, 2010 CFR

...manner suitable for the purpose of the space. (b) A means must be provided...vents and ventilators. (c) Living spaces must be ventilated by a mechanical...vessel's design waterline length times its maximum beam. Living...

2010-10-01

385

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

386

Natural ventilation : design for suburban houses in Thailand  

E-print Network

Natural Ventilation is the most effective passive cooling design strategy for architecture in hot and humid climates. In Thailand, natural ventilation has been the most essential element in the vernacular architecture such ...

Tantasavasdi, Chalermwat, 1971-

1998-01-01

387

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

388

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

389

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

390

Influence of perfusion flow rate on uptake and pharmacodynamics of quinidine in isolated perfused rat heart.  

PubMed

With the single-pass isolated perfused rat heart preparation, we examined the effect of perfusate flow rate on the time course of quinidine output concentration (Cout) and the change in the QT interval (delta QT) on the electrocardiogram. Four hearts were perfused at 5.6 mL/min with quinidine (20 microM) for 25-45 min. This was followed by a 50-min washout period with drug-free perfusate. This procedure was repeated four times in each heart. Using a one-compartment model, the rate constants calculated from the time course of Cout (k) and delta QT (Ke) were similar (p > 0.05) and did not vary among the five phases. A zero-time intercept for Cout indicated shunting of perfusate (1.2-13.6%), from which the coronary output concentration (Ccor) and coronary flow rate were calculated. These experiments were repeated in another six hearts, except flow rates of 2, 4, 6, 8, and 2 mL/min were used in each phase. Equilibration of Cout and delta QT was faster with increasing flow rate, and ke and k were similar at each flow rate (p > 0.05). A modified Kety-Renkin-Crone equation was fitted to values for k and coronary flow rate. The mean permeability surface product estimate was 15.3 +/- 3.0 mL/min/g heart, which in comparison with the highest flow rate used (9 mL/min/g heart) suggests that quinidine has intermediate permeability. The excellent fit obtained indicates that a more complex model, incorporating heterogeneous flows or opening of capillaries at higher flows, was not necessary.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8169775

Huang, J L; Morgan, D J

1994-02-01

391

Studies of generalized elemental imbalances in neurological disease patients using INAA (instrumental neutron activation analysis)  

SciTech Connect

Evidence has been presented in the literature to implicate trace elements in the etiology of several age-related neurological diseases. Most of these studies are based on brain analyses. Using instrumental neutron activation analysis (INAA), we have observed trace element imbalances in brains of patients with Alzheimer's disease, amyotrophic lateral sclerosis (ALS), and Picks's disease. The most prevalent elemental imbalances found in the brain were for bromine, mercury, and the alkali metals. In this study the authors report INAA studies of trace elements in nonneural tissues from Alzheimer's disease and ALS patients. Samples from household relatives were collected for use as controls wherever possible. Hair samples were washed according to the International Atomic Energy Agency recommended procedure. Fingernail samples were scraped with a quartz knife prior to washing by the same procedure. For ALS patients, blood samples were also collected. These data indicate that elemental imbalances in Alzheimer's disease and ALS are not restricted to the brain. Many elements perturbed in the brain are also altered in the several nonneural tissues examined to date. The imbalances in different tissues, however, are not always in the same direction. The changes observed may represent causes, effects, or simply epiphenomena. Longitudinal studies of nonneural tissues and blood, as well as tissue microprobe analyses at the cellular and subcellular level, will be required in order to better assess the role of trace elements in the etiology of these diseases.

Ehmann, W.D.; Vance, D.E.; Khare, S.S.; Kasarskis, E.J.; Markesbery, W.R.

1988-01-01

392

Obesity results from an imbalance between caloric intake and energy expenditure, which  

E-print Network

Obesity results from an imbalance between caloric intake and energy expenditure, which is partly proteins of the brown adi- pose tissue (BAT) involved in thermo-gen- esis. Subjects: 238 morbidly obese and 911 non-obese Caucasians subjects. Results: A high prevalence (27%) in French Caucasians of the A

Paris-Sud XI, Université de

393

Earth's Energy Imbalance and Implications James Hansen, Makiko Sato, Pushker Kharecha  

E-print Network

1 Earth's Energy Imbalance and Implications James Hansen, Makiko Sato, Pushker Kharecha NASA Goddard Institute for Space Studies, New York, NY 10025, USA Columbia University Earth Institute, New York that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during

Hansen, James E.

394

A comparison of isokinetic and functional methods of assessing bilateral strength imbalance.  

PubMed

Muscle strength imbalances have been linked with poor agility performance and higher injury risk. Isokinetic dynamometry has been used to investigate such imbalances; however, this method is impractical and inaccessible for most strength and conditioning coaches. The aim of the study was to compare isokinetic dynamometry with functional field tests for assessing bilateral strength imbalance. Thirteen male athletes from various sports (mean+/-SD: age 21+/-1.1 years, height 179.8+/-7.0 cm, body mass 80.8+/-9.7 kg) participated in the study. Knee flexor and extensor strength at 60 degrees.s(-1) was assessed for both limbs with the use of isokinetic dynamometry. Field tests involved seated unilateral leg press, horizontal hop, single-leg vertical and drop jumps. Significant differences (p<0.01) were found when comparing strength dominant (D) and nondominant (ND) limbs for all strength measures, ranging from 4.5% (hop test) to 12.4% (eccentric extension). No significant differences between the right and left limbs were found (p>0.05). No significant relationships between strength D/ND ratios of isokinetic variables and the field tests were evident (p>0.05). The findings provide support for the use of field tests to detect imbalances between lower limbs, but the ultimate choice of test used should depend on the specific strength quality that predominates in the sport. PMID:20508458

Jones, Paul A; Bampouras, Theodoros M

2010-06-01

395

Diagnosis of Micronutrient Imbalance in Lime Crop in Semi-arid Region of Rajasthan, India  

Microsoft Academic Search

Low and unstable fruit yield, poor quality of fruits, and excessive fruit dropping are major problems in a lime crop and are due to either micronutrient deficiencies or nutrient imbalance. A study was conducted to assess the micronutrient status in a lime orchard at the Central Soil and Water Conservation Research and Training Institute (CSWCRTI)’s research farm in Kota, Rajasthan,

J. Somasundaram; H. R. Meena; R. K. Singh; S. N. Prasad; A. K. Parandiyal

2011-01-01

396

Mental retardation in Down syndrome: From gene dosage imbalance to molecular and cellular mechanisms  

Microsoft Academic Search

Down syndrome (DS), the most frequent genetic disorder leading to mental retardation (MR), is caused by three copies of human chromosome 21 (HC21). Trisomic and transgenic mouse models for DS allow genetic dissection of DS neurological and cognitive disorders in view to identify genes responsible for these phenotypes. The effects of the gene dosage imbalance on DS phenotypes are explained

Mohammed Rachidi; Carmela Lopes

2007-01-01

397

A Tough Time to Be a Girl: Gender Imbalance on Campuses  

ERIC Educational Resources Information Center

American colleges are undergoing a striking gender shift. In 2015 the average college graduating class will be 60-percent female, according to the U.S. Education Department. It appears that the stark gender imbalances in American colleges nowadays is acting as an accelerant on the hookup culture among students. As a result of the rising gender…

Whitmire, Richard

2008-01-01

398

ADAPTIVE COMPENSATION OF FREQUENCY SELECTIVE IQ IMBALANCE AND CARRIER FREQUENCY OFFSET FOR OFDM BASED RECEIVERS  

E-print Network

],[5] etc. Hence, a lot of effort is spent in developing integrated, cost and power efficient OFDM systems the radio frequency (RF) signal directly to baseband (BB) without any intermediate frequencies (IF). However. Along with IQ imbalance, OFDM systems are also very sensitive to car- rier frequency offset (CFO

399

Evidence for metabolic imbalance of vitamin A2 in wild fish chronically exposed to metals  

E-print Network

Evidence for metabolic imbalance of vitamin A2 in wild fish chronically exposed to metals Michel A was observed. These results suggest that the enzymes and the binding proteins involved in vitamin A homeostasis are inhibited by the presence of Cd. Alternatively, the increase in tissue vitamin A (antioxidant) levels could

Bernatchez, Louis

400

IMBALANCE OF THE EARTH SYSTEM IN TERMS OF ENTROPY Yangang Liu, Wei Wu and Warren Wiscombe  

E-print Network

imbalance by building close connection between incoming shortwave and outgoing longwave radiation such as highly uncertain climate sensitivity and cloud feedbacks. This study explores a new theoretical framework principles (e.g., energy conservation). In particular, we show that even at steady state, radiation entropy

Johnson, Peter D.

401

Current Account Imbalances in the Monetary Union and the Great Recession: Causes and Policies  

Microsoft Academic Search

Current account imbalances within the eurozone are at the roots of its economic crisis. We argue that, though relevant, emphasis should shift from competitiveness to differential rates of growth of domestic demand as its chief explanatory factor. Euro core countries have experienced a shortage of domestic demand, with wage restraint playing a key role. This has led them to experience

Eladio Febrero

2011-01-01

402

Economic concepts to address future water supply-demand imbalances in Iran, Morocco and Saudi Arabia  

NASA Astrophysics Data System (ADS)

In Middle East and North Africa (MENA) countries, renewable groundwater and surface water supply are limited while demand for water is growing rapidly. Climate change is expected to increase water demand even further. The main aim of this paper is to evaluate the water supply-demand imbalances in Iran, Morocco and Saudi Arabia in 2040-2050 under dry, average and wet climate change projections and to show on the basis of the marginal cost and marginal value of water the optimum mix of supply-side and demand-side adjustments to address the imbalance. A hydrological model has been used to estimate the water supply-demand imbalance. Water supply and demand curves have been used to explore for which (marginal value of) water usage the marginal cost of supply-enhancement becomes too expensive. The results indicate that in the future in all cases, except in Iran under the wet climate projection, the quantity of water demanded has to be reduced considerably to address the imbalance, which is indeed what is currently happening already.

Hellegers, Petra; Immerzeel, Walter; Droogers, Peter

2013-10-01

403

Compensation of rotor imbalance for precision rotation of a planar magnetic bearing rotor  

Microsoft Academic Search

Magnetic bearings provide an alternative for achieving precision rotation. But the rotational accuracy is sensitive to rotor imbalance. The system we study is a planar rotor supported by aerostatic suspension and positioned by a radial magnetic bearing of nanometer precision. We present compensation designs and experiment results for precision rotation about the geometric center and the mass center, respectively. In

L. Li; T. Shinshi; C. Iijima; X. Zhang; A. Shimokohbe

2003-01-01

404

Clinical review: Independent lung ventilation in critical care  

Microsoft Academic Search

Independent lung ventilation (ILV) can be classified into anatomical and physiological lung separation. It requires either endobronchial blockade or double-lumen endotracheal tube intubation. Endobronchial blockade or selective double-lumen tube ventilation may necessitate temporary one lung ventilation. Anatomical lung separation isolates a diseased lung from contaminating the non-diseased lung. Physiological lung separation ventilates each lung as an independent unit. There are

Devanand Anantham; Raghuram Jagadesan; Philip Eng Cher Tiew

2005-01-01

405

Automated analysis of Xe-133 pulmonary ventilation (AAPV) in children  

NASA Astrophysics Data System (ADS)

In this study, an automated analysis of pulmonary ventilation (AAPV) was developed to visualize the ventilation in pediatric lungs using dynamic Xe-133 scintigraphy. AAPV is a software algorithm that converts a dynamic series of Xe- 133 images into four functional images: equilibrium, washout halftime, residual, and clearance rate by analyzing pixelbased activity. Compared to conventional methods of calculating global or regional ventilation parameters, AAPV provides a visual representation of pulmonary ventilation functions.

Cao, Xinhua; Treves, S. Ted

2011-03-01

406

A practical guide to neonatal volume guarantee ventilation  

Microsoft Academic Search

A recent systematic review and meta-analysis shows that volume-targeted ventilation (VTV) compared with pressure-limited ventilation (PLV) reduce death and bronchopulmonary dysplasia, pneumothorax, hypocarbia and severe cranial ultrasound abnormalities. In this paper, we present published research and our experience with volume guarantee (VG) ventilation, a VTV mode available on the Dräger Babylog 8000plus and VN500 ventilators. The VG algorithm measures the

C Klingenberg; K I Wheeler; P G Davis; C J Morley

2011-01-01

407

Patient Safety: Reduce the Risk of Ventilator-Associated Pneumonia  

Microsoft Academic Search

ISSUE: Ventilator-associated pneumonia (VAP) is a common complication in the intensive care unit (ICU) in ventilated patients.PROJECT: To reduce the risk of healthcare-acquired, ventilator-associated pneumonia with nursing practice improvements and a comprehensive oral care program. A multidisciplinary team reviewed infection rates and current patient-care practices of ventilated patients in the ICU. Actions were taken and evaluated during a 6-month period.

R. Hall; N. Simpson

2004-01-01

408

“Back Then It Was Legal” The Epistemological Imbalance in Readings of Biblical and Ancient Near Eastern Rape Legislation  

Microsoft Academic Search

The article examines the epistemological imbalance that currently exists in the area of biblical and ancient Near Eastern rape laws. The imbalance reflects a larger development in western intellectual discourse in which we are moving from an empiricist-positivist epistemology to a postmodern epistemology. The former is characteristic of the modern western worldview and assumes objectivity, value neutrality, and universality. It

Susanne Scholz

2005-01-01

409

A special compressor used in portable mechanical ventilators  

Microsoft Academic Search

Portable mechanical ventilators currently used on the battlefield are designed to maintain life support. But it's still difficult to design an appropriate compressor for portable mechanical ventilators. A new type of compressor with small size, high output pressure, and high flow-rate is designed to satisfy the demands of portable mechanical ventilators. The special compressor has a new structure which is

Shilin Wu; Qi Zhang; Zhiping Huang; Jiulong Xiong

2009-01-01

410

Implementation of a Respiratory Drive Monitor on a Servo Ventilator  

Microsoft Academic Search

Objective. To design and evaluate a clinical monitor of respiratory drive (P0.1) and other respiratory variables in a simple way, using a commercial ventilator. Methods. Nine healthy males were studied as they were breathing spontaneously in a Servo 900C Ventilator, at rest and during light exercise (50 W). The ventilator was slightly modified to improve its mechanical performance during spontaneous

Lars Gösta Hellström; Hans Larsson; Dag Linnarsson

1999-01-01

411

Position paper -- Tank ventilation system design air flow rates  

Microsoft Academic Search

The purpose of this paper is to document a project position on required ventilation system design air flow rates for the waste storage tanks currently being designed by project W-236A, the Multi-Function Waste Tank Facility (MWTF). The Title 1 design primary tank heat removal system consists of two systems: a primary tank vapor space ventilation system; and an annulus ventilation

Goolsby

1995-01-01

412

Ventilation planning at Energy West's Deer Creek mine  

SciTech Connect

In 2004 ventilation planning was initiated to exploit a remote area of Deer Creek mine's reserve (near Huntington, Utah), the Mill Fork Area, located under a mountain. A push-pull ventilation system was selected. This article details the design process of the ventilation system upgrade, the procurement process for the new fans, and the new fan startup testing. 5 figs., 1 photo.

Tonc, L.; Prosser, B.; Gamble, G. [Pacific Corp., Huntington, UT (United States)

2009-08-15

413

[Monitorization of respiratory mechanics in the ventilated patient].  

PubMed

Monitoring during mechanical ventilation allows the measurement of different parameters of respiratory mechanics. Accurate interpretation of these data can be useful for characterizing the situation of the different components of the respiratory system, and for guiding ventilator settings. In this review, we describe the basic concepts of respiratory mechanics, their interpretation, and their potential use in fine-tuning mechanical ventilation. PMID:24199991

García-Prieto, E; Amado-Rodríguez, L; Albaiceta, G M

2014-01-01

414

Energy use for ventilation systems in underground car parks  

Microsoft Academic Search

The use of energy for operating ventilation systems in underground car parks in Hong Kong is considered. A site survey has been carried out in 22 underground car parks. The physical size, configurations, and electrical rating of ventilation fans were the main matters of interest. The indoor thermal environments, carbon monoxide concentrations, and operation of ventilation systems were examined. Mathematical

M. Y. Chan; J. Burnett; W. K. Chow

1998-01-01

415

Numerical studies on performance evaluation of tunnel ventilation safety systems  

Microsoft Academic Search

The performance of tunnel safety systems for fire protection and ventilation provision is evaluated using Computational Fluid Dynamics (CFD). Ventilation safety systems commonly used in tunnels are reviewed first. The safety aspects related to tunnel fire and ventilation are then discussed. Air flow induced by an accidental vehicular fire in a tunnel is simulated using CFD. Based on the results,

Jojo S. M Li; W. K Chow

2003-01-01

416

Metabolic Response of Perfused Livers to Various Oxygenation Conditions  

E-print Network

in perfusate without RBCs was just sufficient to meet the average oxygen demand of the liver but wouldARTICLE Metabolic Response of Perfused Livers to Various Oxygenation Conditions Mehmet A. Orman,1 Marianthi G. Ierapetritou,1 Ioannis P. Androulakis,1,2 Francois Berthiaume2 1 Department of Chemical

Androulakis, Ioannis (Yannis)

417

Pulsed laser-Doppler flowmetry for monitoring deep perfusion  

NASA Astrophysics Data System (ADS)

Measurements have been carried out using a pulsed laser-Doppler setup. The main advantage of pulsing a laser-diode is that much higher peak powers can be used, allowing a larger source-detector separation, resulting in a larger penetration depth. The method enables e.g. monitoring of cerebral perfusion as well as monitoring perfusion through organs (e.g. kidney).

Kolkman, Roy G. M.; Hondebrink, Erwin; Bolt, Rene A.; Steenbergen, Wiendelt; de Mul, Frits F. M.

2001-10-01

418

THE INTRINSIC PROPERTIES OF AN IN SITU PERFUSED CROCODILE HEART  

Microsoft Academic Search

Summary An in situ perfused crocodile (Crocodylus porosus) heart preparation was developed to investigate the effects of input and output pressure on cardiac dynamics and to determine the conditions that lead to a right-to-left cardiac shunt. The pericardium was kept intact, both the left and right atria were perfused and all three outflow tracts (right aortic, left aortic and pulmonary)

CRAIG E. FRANKLIN

1994-01-01

419

Dynamic Magnetic Resonance Perfusion Imaging of Brain Tumors  

Microsoft Academic Search

In this paper, we review the technique of contrast- enhanced magnetic resonance (MR) perfusion imaging of brain neoplasms, with an emphasis on its clinical applica- tions and utility. We start with a discussion of MR perfu- sion techniques available today and their relative merits and shortcomings. Next, the ability of MR perfusion to provide a preoperative assessment of tumor histology

DIEGO J. COVARRUBIAS; BRUCE R. ROSEN; MICHAEL H. LEVa

420

Sinusoidal heating method to noninvasively measure tissue perfusion  

Microsoft Academic Search

Noninvasively measuring the tissue blood perfusion has been an important however difficult problem in the biomedical engineering field. Based on the newly developed phase-shift principle, an improved sinusoidal heating method to estimate the perfusion was proposed in this paper to replace the original heating algorithm. The phase shift between the sinusoidal heat flux and the surface temperature response was both

Jing Liu; Yi-xin Zhou; Zhong-shan Deng

2002-01-01

421

Original article Perfusion of trout liver in situ.  

E-print Network

Original article Perfusion of trout liver in situ. Description and validation of the technique AI; The aim of this study was to develop a method for perfusing isolated trout livers that would make consumption, lactate dehydrogenase activity and liver metabolic capacity. In addition, a histological study

Paris-Sud XI, Université de

422

High speed perfusion imaging based on laser speckle fluctuations  

Microsoft Academic Search

Noninvasive methods to visualize blood flow in tissue are important in the clinical environment. Most methods use dynamic speckles to measure the level of perfusion. The most well-known techniques based on these speckle patterns are laser Doppler perfusion imaging (LDPI) and laser speckle contrast analysis (LASCA). For LASCA measurements an inexpensive camera which can achieve a frame-rate of 200 Hz

Matthijs Johannes Draijer

2010-01-01

423

Photospheric Magnetic Field: Relationship Between North-South Asymmetry and Flux Imbalance  

NASA Astrophysics Data System (ADS)

Photospheric magnetic fields were studied using the Kitt Peak synoptic maps for 1976 - 2003. Only strong magnetic fields ( B>100 G) of the equatorial region were taken into account. The north-south asymmetry of the magnetic fluxes was considered as well as the imbalance between positive and negative fluxes. The north-south asymmetry displays a regular alternation of the dominant hemisphere during the solar cycle: the northern hemisphere dominated in the ascending phase, the southern one in the descending phase during Solar Cycles 21 - 23. The sign of the imbalance did not change during the 11 years from one polar-field reversal to the next and always coincided with the sign of the Sun's polar magnetic field in the northern hemisphere. The dominant sign of leading sunspots in one of the hemispheres determines the sign of the magnetic-flux imbalance. The sign of the north-south asymmetry of the magnetic fluxes and the sign of the imbalance of the positive and the negative fluxes are related to the quarter of the 22-year magnetic cycle where the magnetic configuration of the Sun remains constant (from the minimum where the sunspot sign changes according to Hale's law to the magnetic-field reversal and from the reversal to the minimum). The sign of the north-south asymmetry for the time interval considered was determined by the phase of the 11-year cycle (before or after the reversal); the sign of the imbalance of the positive and the negative fluxes depends on both the phase of the 11-year cycle and on the parity of the solar cycle. The results obtained demonstrate the connection of the magnetic fields in active regions with the Sun's polar magnetic field in the northern hemisphere.

Vernova, E. S.; Tyasto, M. I.; Baranov, D. G.

2014-08-01

424

General characteristics of patients with electrolyte imbalance admitted to emergency department  

PubMed Central

BACKGROUND: Fluid and electrolyte balance is a key concept to understand for maintaining homeostasis, and for a successful treatment of many metabolic disorders. There are various regulating mechanisms for the equilibrium of electrolytes in organisms. Disorders of these mechanisms result in electrolyte imbalances that may be life-threatening clinical conditions. In this study we defined the electrolyte imbalance characteristics of patients admitted to our emergency department. METHODS: This study was conducted in the Emergency Department (ED) of Uludag University Faculty of Medicine, and included 996 patients over 18 years of age. All patients had electrolyte imbalance, with various etiologies other than traumatic origin. Demographic and clinical parameters were collected after obtaining informed consent from the patients. The ethical committee of the university approved this study. RESULTS: The mean age of the patients was 59.28±16.79, and 55% of the patients were male. The common symptoms of the patients were dyspnea (14.7%), fever (13.7%), and systemic deterioration (11.9%); but the most and least frequent electrolyte imbalances were hyponatremia and hypermagnesemia, respectively. Most frequent findings in physical examination were confusion (14%), edema (10%) and rales (9%); and most frequent pathological findings in ECG were tachycardia in 24%, and atrial fibrillation in 7% of the patients. Most frequent comorbidity was malignancy (39%). Most frequent diagnoses in the patients were sepsis (11%), pneumonia (9%), and acute renal failure (7%). CONCLUSIONS: Electrolyte imbalances are of particular importance in the treatment of ED patients. Therefore, ED physicians must be acknowledged of their fluid-electrolyte balance dynamics and general characteristics.

Balc?, Arif Kadri; Koksal, Ozlem; Kose, Ataman; Armagan, Erol; Ozdemir, Fatma; Inal, Taylan; Oner, Nuran

2013-01-01

425

Sodium Movements in Perfused Squid Giant Axons  

PubMed Central

Sodium movements in internally perfused giant axons from the squid Dosidicus gigas were studied with varying internal sodium concentrations and with fluoride as the internal anion. It was found that as the internal concentration of sodium was increased from 2 to 200 mM the resting sodium efflux increased from 0.09 to 34.0 pmoles/cm2sec and the average resting sodium influx increased from 42.9 to 64.5 pmoles/cm2sec but this last change was not statistically significant. When perfusing with a mixture of 500 mM K glutamate and 100 mM Na glutamate the resting efflux was 10 ± 3 pmoles/cm2sec and 41 ± 10 pmoles/cm2sec for sodium influx. Increasing the internal sodium concentration also increased both the extra influx and the extra efflux of sodium due to impulse propagation. At any given internal sodium concentration the net extra influx was about 5 pmoles/cm2impulse. This finding supports the notion that the inward current generated in a propagated action potential can be completely accounted for by movements of sodium. PMID:5672003

Rojas, Eduardo; Canessa-Fischer, Mitzy

1968-01-01

426

Experimental simulation of wind driven cross-ventilation in a naturally ventilated building  

E-print Network

A device was designed and constructed to simulate cross-ventilation through a building due to natural wind. The wind driver device was designed for use with a one tenth scale model of an open floor plan office building in ...

Hult, Erin L. (Erin Luelle), 1982-

2004-01-01

427

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.  

Code of Federal Regulations, 2013 CFR

...103-1 Section 111.103-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation...

2013-10-01

428

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.  

Code of Federal Regulations, 2010 CFR

...103-1 Section 111.103-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation...

2010-10-01

429

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.  

Code of Federal Regulations, 2011 CFR

...103-1 Section 111.103-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation...

2011-10-01

430

VENTILATING HORNETS DISPLAY DIFFERENTIAL BODY TEMPERATURE  

Microsoft Academic Search

abdomen bent downward at a 90? angle to the thorax, their antennae vibrating, and their wings beating rapidly for minutes at a time. Eventually these hornets leave their position, either to retreat into the nest or else to fly off to the field, and are replaced by new hornets that assume the ventilation task. Infra-red (IR) photography reveals that in

Jacob S. Ishay; Marian Plotkin; Natalya Ermakov; Alon Goren; David J. Bergman

2006-01-01

431

Glacial Ventilation of the North Pacific  

Microsoft Academic Search

Previous work on sediment cores from the North Pacific showed that above ~2 km d13C on the benthic foram Cibicidoides was higher during glacial time than it is today, after correcting for secular change of ~0.3 permil. This led to the suggestion that the ocean was better ventilated either through greater transport of a paleo North Pacific Intermediate Water, or

L. D. Keigwin; O. Marchal

2004-01-01

432

Ventilation Based on ASHRAE 62.2  

E-print Network

in this report. #12;1 2008 Building Energy Efficiency Standards Residential Indoor Air Quality and Mechanical/ASHRAE Standard 62.2-2007, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings (ASHRAE Indoor Air Quality in Low-Rise Residential Buildings (ASHRAE 62.2). In California, the requirements

433

Reduceret energiforbrug til ventilation af bygninger  

E-print Network

the ventilation required for acceptable indoor air quality is reduced by selecting low­polluting building materials, without compromising the indoor air quality. List of publications: Present report is based on perceived indoor air quality", Proceedings of CLIMA 2007, Helsinki, Finland, on CD-ROM. · P. Wargocki, H

434

Performance Assessment of Photovoltaic Attic Ventilator Fans  

E-print Network

Controlling summer attic heat gain is important to reducing air conditioning energy use in homes in hot-humid climates. Both heat transfer through ceilings and t attic duct systems can make up a large part of peak cooling demand, Attic ventilation...

Parker, D. S.; Sherwin, J. R.

2000-01-01

435

Hysteresis effects in hybrid building ventilation  

E-print Network

-intensive HVAC systems · For example, in USA alone, 250 TWh/yr. are consumed in cooling commercial space Ghiaus Indoor air quality #12;Engineering dilemma: · Developed world relies for ventilation on expensive radiation, external wind forcing and internal heat gains e.g. due to electrical equipment or building

Flynn, Morris R.

436

Model `680', `681' & `683' Animal Ventilator  

E-print Network

Model `680', `681' & `683' Animal Ventilator Repair Manual #12;1 HarvardApparatusModels'680 as to workmanship or material. This warranty does not extend to damage resulting from misuse,neglect or abuse unless an RMA (returned materials authorization) number has been issued by our customer service

Kleinfeld, David

437

Anxiety and Agitation in Mechanically Ventilated Patients  

PubMed Central

During an ethnography conducted in an intensive care unit (ICU), we found that anxiety and agitation occurred frequently, and were important considerations in the care of 30 patients weaning from prolonged mechanical ventilation. We conducted a secondary analysis to (a) describe characteristics of anxiety and agitation experienced by mechanically ventilated patients; (b) explore how clinicians recognize and interpret anxiety and agitation and (c) describe strategies and interventions used to manage anxiety and agitation with mechanically ventilated patients. We constructed the Anxiety-Agitation in Mechanical Ventilation Model to illustrate the multidimensional features of symptom recognition and management. Patients’ ability to interact with the environment served as a basis for identification and management of anxiety or agitation. Clinicians’ attributions about anxiety or agitation and “knowing the patient” contributed to their assessment of patient responses. Clinicians chose strategies to overcome either the stimulus or patient’s appraisal of risk of the stimulus. This article contributes to the body of knowledge about symptom recognition and management in the ICU by providing a comprehensive model to guide future research and practice. PMID:21908706

Tate, Judith Ann; Dabbs, Annette Devito; Hoffman, Leslie; Milbrandt, Eric; Happ, Mary Beth

2013-01-01

438

Ozonolysis of monoterpenes in mechanical ventilation systems  

NASA Astrophysics Data System (ADS)

In this investigation the ozonolysis of of three monoterpenes ( ?-pinene, ?3-carene and limonene) was studied was studied in authentic mechanical ventilation systems, that included either a cross flow or a rotary heat exchanger. The effects of varying three experimental parameters were investigated: the level of ozone (25 and 75 ppb), the reaction time (25 and 75 s), and the surface area in the ventilation duct (14.8 and 29.5 m 2). The initial concentration of each of the monoterpenes was 20 ppb in every experiment, and 1-16% of the ?-pinene, <0.5-13% of the ?3-carene, and <0.5-16% of the limonene reacted. The effects of humidity (g m -3) and temperature of the outdoor and supply air, and water losses in the ventilation duct, were also evaluated. Experiments were based on a chemometric statistical design. Comparison of the results to theoretically calculated values showed that theoretical calculations underestimated the amounts that reacted in the ventilation systems by factors of 2-13, depending on the monoterpene and experimental settings.

Fick, Jerker; Pommer, Linda; Åstrand, Anders; Östin, Ronny; Nilsson, Calle; Andersson, Barbro

439

Metrics for Air Conditioning & Refrigeration, Heating, Ventilating.  

ERIC Educational Resources Information Center

Designed to meet the job-related metric measurement needs of the air conditioning and refrigeration, heating and ventilating student, this instructional package is one of three for the construction occupations cluster, part of a set of 55 packages for metric instruction in different occupations. The package is intended for students who already…

Cooper, Gloria S., Ed.; Magisos, Joel H., Ed.

440

Buoyancy-Affected Flows in Ventilated Rooms  

Microsoft Academic Search

Calculations of velocity and temperature distributions in rooms with ventilation arrangements are reported. The method involves the solution, in finite-difference form, of two-dimensional equations for the conservation of mass, momentum, energy, turbulence energy, and dissipation rate, with algebraic expressions for the turbulent viscosity and heat diffusivity. The results are shown to be in reasonable agreement with available experimental data and

P. V. Nielsen; A. Restivo; J. H. Whitelaw

1979-01-01

441

Ventilation index of helicopter pilot suits  

Microsoft Academic Search

The main function of helicopter pilot suits used in offshore flights is to provide thermal protection in the event of cold water immersion and to allow maintenance of thermal comfort during normal use. As part of a larger study to assess the thermal characteristics of helicopter pilot suits, the ventilation index of four suits was determined using the methods outlined

PATRICK J. SULLIVAN; IGOR B. MEKJAVIC; NAOSHI KAKITSUBA

1987-01-01

442

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...OTHER HAZARDOUS MATERIALS Chemical Stores and/or Storerooms...20-5 Ventilation. (a) Chemical storerooms shall be equipped...shall be fitted with acceptable flame screens. (4) The control...Provisions shall be made so that the chemical storeroom will be...

2010-10-01

443

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...OTHER HAZARDOUS MATERIALS Chemical Stores and/or Storerooms...20-5 Ventilation. (a) Chemical storerooms shall be equipped...shall be fitted with acceptable flame screens. (4) The control...Provisions shall be made so that the chemical storeroom will be...

2013-10-01

444

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2011 CFR

...OTHER HAZARDOUS MATERIALS Chemical Stores and/or Storerooms...20-5 Ventilation. (a) Chemical storerooms shall be equipped...shall be fitted with acceptable flame screens. (4) The control...Provisions shall be made so that the chemical storeroom will be...

2011-10-01

445

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2012 CFR

...OTHER HAZARDOUS MATERIALS Chemical Stores and/or Storerooms...20-5 Ventilation. (a) Chemical storerooms shall be equipped...shall be fitted with acceptable flame screens. (4) The control...Provisions shall be made so that the chemical storeroom will be...

2012-10-01

446

[Percutaneous tracheostomy in the ventilated patient].  

PubMed

The medical indications of tracheostomy comprise the alleviation of upper airway obstruction; the prevention of laryngeal and upper airway damage due to prolonged translaryngeal intubation in patients subjected to prolonged mechanical ventilation; and the facilitation of airway access for the removal of secretions. Since 1985, percutaneous tracheostomy (PT) has gained widespread acceptance as a method for creating a surgical airway in patients requiring long-term mechanical ventilation. Since then, several comparative trials of PT and surgical tracheostomy have been conducted, and new techniques for PT have been developed. The use of percutaneous dilatation techniques under bronchoscopic control are now increasingly popular throughout the world. Tracheostomy should be performed as soon as the need for prolonged intubation is identified. However a validated model for the prediction of prolonged mechanical ventilation is not available, and the timing of tracheostomy should be individualized. The present review analyzes the state of the art of PT in mechanically ventilated patients--this being regarded by many as the technique of choice in performing tracheostomy in critically ill patients. PMID:23347906

Añón, J M; Araujo, J B; Escuela, M P; González-Higueras, E

2014-04-01

447

Perfluorochemical perfusion of the isolated guinea pig heart.  

PubMed

We studied the influence of a perfluorochemical (PFC) emulsion on the ultrastructure and function of the isolated perfused guinea pig heart compared to a Krebs-Henseleit solution. The PFC perfusion enhanced the force of contraction and reduced the coronary flow rate, but had no influence on the frequency and the oxygen consumption. The positive inotropic action of K-strophanthin and isoproterenol was slightly strengthened, whereas the beta-adrenergic antagonism by propranolol and the vasodilatation by glycerol trinitrate remained unchanged. The positive chronotropic action of isoproterenol was reduced during PFC perfusion. No histological differences depending on the perfusion medium were observed. It is concluded that PFC perfusion improves the functional state of the Langendorff preparation. PMID:6427796

Deutschmann, W; Lindner, E; Deutschländer, N

1984-01-01

448

Bone Flap Perfusion Assessment using Near-Infrared Fluorescence Imaging  

PubMed Central

Background Microsurgical vascularized bone flaps are a versatile technique for reconstructing large bone defects. However, assessment of perfusion is challenging, as clinical examination is difficult intra-operatively and often not possible post-operatively. Therefore, it is important to develop techniques to assess perfusion of vascularized bone flaps, and potentially improve surgical outcomes. Near-infrared (NIR) fluorescence imaging has been previously shown to provide real-time, intra-operative evaluation of vascular perfusion. This pilot study investigates the ability of NIR imaging to assess perfusion of vascularized bone flaps. Materials and Methods Vascularized bone flaps were created on female Yorkshire pigs using well-established models for porcine forelimb osteomyocutaneous flap allotransplantation (N = 8) and hindlimb fibula flaps (N = 8). Imaging of the bone flaps was performed during harvest using the FLARE™ intraoperative fluorescence imaging system following systemic injection of indocyanine green (ICG). Perfusion was also assessed using standard of care by clinical observation and Doppler. NIR fluorescence perfusion assessment was confirmed by intermittent clamping of the vascular pedicle. Results NIR fluorescence imaging can identify bone perfusion at the cut end of the osteotomy site. When the vascular pedicle is clamped or ligated, NIR imaging demonstrates no fluorescence when injected with ICG. With clamp removal, the osteotomy site emits fluorescence indicating bone perfusion. Results using fluorescence imaging show 100% agreement with clinical observation and Doppler. Conclusion Vascularized bone transfers have become an important tool in reconstructive surgery; however, no established techniques adequately assess perfusion. Our pilot study indicates that NIR imaging can provide real-time, intra-operative assessment of bone perfusion. PMID:22664132

Nguyen, John T.; Ashitate, Yoshitomo; Buchanan, Ian A.; Ibrahim, Ahmed M.S.; Gioux, Sylvain; Patel, Priti P.; Frangioni, John V.; Lee, Bernard T.

2012-01-01

449

Relationship between function and perfusion early after acute myocardial infarction.  

PubMed

To assess the relationship between baseline left ventricle function, functional reserve and resting myocardial perfusion in patients with acute myocardial infarction (AMI). After AMI the presence of dysfunctioning but viable myocardium plays a determinant role in clinical outcome. Regional ventricular function was evaluated by echocardiography both in resting conditions and during dobutamine infusion (10 microg/kg/min). Perfusion was assessed by magnetic resonance imaging in a single slice approach where the first pass of an intravenously injected bolus of gadolinium-based contrast agent was followed through six regions of interest within the myocardium. In each patient a region with normal function was used as reference and the cross-correlation coefficient (CCC), which described the myocardial perfusion relatively to the reference region (CCC = 1 means equivalent perfusion), was obtained for the other five myocardial regions. Twenty-two patients were enrolled into the study. Sixty-one segments had normal function and normal perfusion (CCC = 0.92+/-0.23). The perfusion deficit was more marked in the 29 regions with resting akinesia-dyskinesia than in the 20 hypokinetic regions (CCC = 0.71+/-0.45 vs. 0.84+/-0.23; p < 0.05). Out of the 29 regions with resting akinesia-dyskinesia the 13 segments which showed functional improvement following dobutamine had a higher resting perfusion than the 16 segments which were unresponsive to dobutamine (CCC = 0.83+/-0.32 vs. 0.61+/-0.52, p < 0.05). Similarly, out of the 20 regions with resting hypokinesia the 11 segments having functional reserve showed an higher resting perfusion than the segments which did not (0.96+/-0.21 vs. 0.69+/-0.19; p < 0.05). Early after AMI, the perfusion deficit reflects the severity of the mechanical dysfunction. In regions with baseline dyssynergy resting perfusion is, in general, higher when contractile reserve can be elicited by stress-echo. PMID:12025952

Lombardi, M; Kvaerness, J; Torheim, G; Soma, J; Cellerini, F; Consalvo, M; Landini, M C; Cecchi, C A; Michelassi, C; Skjaerpe, T; Jones, R A; Rinck, P A; L'Abbate, A

2001-10-01

450

On The Valuation of Infiltration towards Meeting Residential Ventilation Needs  

SciTech Connect

The purpose of ventilation is dilute or remove indoor contaminants that an occupant is exposed to. It can be provided by mechanical or natural means. In most homes, especially existing homes, infiltration provides the dominant fraction of the ventilation. As we seek to provide acceptable indoor air quality at minimum energy cost, it is important to neither over-ventilate nor under-ventilate. Thus, it becomes critically important to correctly evaluate the contribution infiltration makes to both energy consumption and equivalent ventilation. 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.

Sherman, Max H.

2008-09-01

451

Regional myocardial perfusion rates in patient with coronary artery disease.  

PubMed

Regional myocardial perfusion rates were estimated from the myocardial washout of (133)Xenon in 24 patients with heart disease whose coronary arteriograms were abnormal and 17 similar subjects whose coronary arteriograms were judged to be normal. Disappearance rates of (133)Xe from multiple areas of the heart were monitored externally with a multiple-crystal scintillation camera after the isotope had been injected into a coronary artery and local myocardial perfusion rates were calculated by the Kety formula. The mean myocardial perfusion rates in the left ventricle exceeded those in the right ventricle or atrial regions in subjects without demonstrable coronary artery disease. In this group there was a significant lack of homogeneity of local perfusion rates in left ventricular myocardium; the mean coefficient of variation of left ventricular local perfusion rates was 15.8%. In the patients with radiographically demonstrable coronary artery disease, a variety of myocardial perfusion patterns were observed. Local capillary blood flow rates were depressed throughout the myocardium of patients with diffuse coronary disease but were subnormal only in discrete myocardial regions of others with localized occlusive disease. Local myocardial perfusion rates were similar to those found in the group with normal coronary arteriograms in patients with slight degrees of coronary disease and in those areas of myocardium distal to marked coronary constrictions or occlusions which were well supplied by collateral vessels. In subjects with right coronary disease, the mean right ventricular perfusion rates were significantly subnormal; in seven subjects of this group perfusion of the inferior left ventricle by a dominant right coronary artery was absent or depressed. The average mean left ventricular perfusion rate of 12 subjects with significant disease of two or more branches of the left coronary artery was significantly lower than that of the group with normal left coronary arteriograms. In the patients with abnormal left coronary arteriograms, the average coefficient of variation of local left ventricular perfusion rates was significantly increased (24.8%). The studies provide evidence that coronary artery disease is associated with increased heterogeneity of local myocardial perfusion rates. They indicate that radiographically significant vascular pathology of the right or left coronary artery may be associated with significant reductions of myocardial capillary perfusion in the region supplied by the diseased vessel. PMID:5062613

Cannon, P J; Dell, R B; Dwyer, E M

1972-04-01

452

Mathematical modelling of extracorporeal circulation: simulation of different perfusion regimens.  

PubMed

Computer- and sensor-aided control of the heart-lung machine is considered a major goal for perfusion sciences for the next few years. At present, control of perfusion is achieved by surgeons, anaesthesiologists and perfusionists making short-term decisions, which leads to variations of the perfusion regimens between different centres and even between different teams in the operating theatre. As the basis for an integrated control of extracorporeal circulation (ECC), we proposed a mathematical model for simulating haemodynamics during pulsatile perfusion. This model was then modified to allow it to simulate the effects of different perfusion regimens on arterial haemodynamics and whole body oxygen consumption. The model was constructed on a PC using MATLAB/SIMULINK. The human arterial tree was divided into a multibranch structure consisting of 128 segments characterized by their particular physical properties. Peripheral branches were terminated by a resistance term representing smaller vessels like arterioles and capillaries. Flow and pressure were expressed by the intensity of current and voltage in an electrotechnical analogon; inductivity, resistance and capacitance were implemented according to the physical properties of the arterial tree and the rheology of blood. The effects of different perfusion regimens (pulsatility, flow amount, acid-base regulation) were studied. After introducing an input signal to the model, flow and pressure waves established themselves throughout the simulated arterial tree. During the simulation experiments, marked differences among different perfusion regimens were displayed by the model. Variations in acid-base management mainly influenced the distribution of perfusion: during simulation of low-flow perfusion (1.2 l/min/m2), cerebral blood flow was 6.2 ml/s using an alpha-stat regimen, while it was increased to 9.4 ml/s during pH-stat, caused by an implementation of reduced cerebral resistance. Whole body oxygen consumption was predominantly regulated by the perfusion rate. While central venous oxygen saturation was calculated to be 84.7% during simulation of high-flow perfusion (2.4 l/min/m2), it dropped to 70% during simulation of low-flow perfusion regimens. The model proved to be useful for a realistic simulation of different perfusion regimens. Therefore it can be considered a continuing step for the derivation of a 'state' observer leading to the realization of an automatically controlled heart-lung machine. PMID:10499647

Bauernschmitt, R; Naujokat, E; Mehmanesh, H; Schulz, S; Vahl, C F; Hagl, S; Lange, R

1999-09-01

453

Cerebral perfusion in sepsis-associated delirium  

PubMed Central

Introduction The pathophysiology of sepsis-associated delirium is not completely understood and the data on cerebral perfusion in sepsis are conflicting. We tested the hypothesis that cerebral perfusion and selected serum markers of inflammation and delirium differ in septic patients with and without sepsis-associated delirium. Methods We investigated 23 adult patients with sepsis, severe sepsis, or septic shock with an extracranial focus of infection and no history of intracranial pathology. Patients were investigated after stabilisation within 48 hours after admission to the intensive care unit. Sepsis-associated delirium was diagnosed using the confusion assessment method for the intensive care unit. Mean arterial pressure (MAP), blood flow velocity (FV) in the middle cerebral artery using transcranial Doppler, and cerebral tissue oxygenation using near-infrared spectroscopy were monitored for 1 hour. An index of cerebrovascular autoregulation was calculated from MAP and FV data. C-reactive protein (CRP), interleukin-6 (IL-6), S-100?, and cortisol were measured during each data acquisition. Results Data from 16 patients, of whom 12 had sepsis-associated delirium, were analysed. There were no significant correlations or associations between MAP, cerebral blood FV, or tissue oxygenation and sepsis-associated delirium. However, we found a significant association between sepsis-associated delirium and disturbed autoregulation (P = 0.015). IL-6 did not differ between patients with and without sepsis-associated delirium, but we found a significant association between elevated CRP (P = 0.008), S-100? (P = 0.029), and cortisol (P = 0.011) and sepsis-associated delirium. Elevated CRP was significantly correlated with disturbed autoregulation (Spearman rho = 0.62, P = 0.010). Conclusion In this small group of patients, cerebral perfusion assessed with transcranial Doppler and near-infrared spectroscopy did not differ between patients with and without sepsis-associated delirium. However, the state of autoregulation differed between the two groups. This may be due to inflammation impeding cerebrovascular endothelial function. Further investigations defining the role of S-100? and cortisol in the diagnosis of sepsis-associated delirium are warranted. Trial registration ClinicalTrials.gov NCT00410111. PMID:18457586

Pfister, David; Siegemund, Martin; Dell-Kuster, Salome; Smielewski, Peter; Ruegg, Stephan; Strebel, Stephan P; Marsch, Stephan CU; Pargger, Hans; Steiner, Luzius A

2008-01-01

454

Predicting radiotherapy-induced cardiac perfusion defects.  

PubMed

The purpose of this work is to compare the efficacy of mathematical models in predicting the occurrence of radiotherapy-induced left ventricular perfusion defects assessed using single-photon emission computed tomography (SPECT). The basis of this study is data from 73 left-sided breast/ chestwall patients treated with tangential photon fields. The mathematical models compared were three commonly used parametric models [Lyman normal tissue complication probability (LNTCP), relative serialty (RS), generalized equivalent uniform dose (gEUD)] and a nonparametric model (Linear discriminant analysis--LDA). Data used by the models were the left ventricular dose--volume histograms, or SPECT-based dose-function histograms, and the presence/absence of SPECT perfusion defects 6 months postradiation therapy (21 patients developed defects). For the parametric models, maximum likelihood estimation and F-tests were used to fit the model parameters. The nonparametric LDA model step-wise selected features (volumes/function above dose levels) using a method based on receiver operating characteristics (ROC) analysis to be