Serotonin constricts coronary arteries with endothelial dysfunction, a common abnormality in cardiac transplant recipients. To assess whether endothelial dysfunction is associated with myocardial blood flow (MBF) abnormalities, 24 patients were studied 1 to 12 months after transplantation. Serotonin in increasing doses (1, 10, and 20 micrograms/min for 2.5 min each) was infused into the coronary circulation. Diameters were measured by quantitative angiography. Fourteen patients (group A) had a pronounced artery constriction (diameter reduction | 40%), while in 10 other patients (group B), such a constriction was never reached. No patient had evidence of rejection and all had angiographically normal coronary arteries. MBF was measured at rest and after intravenous dipyridamole with dynamic nitrogen-13 ammonia positron emission tomography (PET). The resting MBF was higher in group A than in group B (94 +/- 12 vs 74 +/- 15 ml/min/100 g of tissue; p | 0.05). During dipyridamole, MBF was not significantly
... $\small{^{15}N-Chlorocholine}$ Chloride ($\small{^{15}N-CCC}$) Diets - Atom Percentage Excess Nitrogen-15;Delta Nitrogen-15 Excess;Laying Hen Tissues;Nitrogen-15;
These are some of the areas that have caused consistent coding and billing problems across the country-and in six months it will be time to forget everything we currently know about coding and billing for myocardial PET.. Get Ready to Reset. Going into effect January 1, 2020, the current CPT® codes for myocardial PET (78459, 78491, 78492) are undergoing description revisions and there will be an additional six new CPT codes introduced to separately identify component services of cardiac PET. Additionally, add-on code 0482T (absolute quantification of myocardial blood flow) will be deleted, presumably to be included in one of the new cardiac PET codes being released.. The unknowns: What the revisions to the existing codes will be, what the new codes will be, what the new descriptions will entail, what the guidelines for use will look like or if there will be any coverage updates.. The confirmed truth: These changes are going to have a significant impact on anyone responsible for coding and ...
Read chapter BIBLIOGRAPHY: Synthesis of Carbon-11, Fluorine-18, and Nitrogen-13 Labeled Radiotracers for Biomedical Applications...
GIVENS, WYATT WENDELL. "GAMMA RADIATIONS FROM EXCITED STATES OF NITROGEN-16, OXYGEN-19, AND NEON-19." (1963) Diss., Rice University. https://hdl.handle.net/1911/14127 ...
We are concerned these reductions will drive cardiac PET services out of physician offices, where the majority of cardiac PET is provided, and into hospitals which could limit patient access to this important imaging modality, particularly in rural and underserved areas, and increase beneficiary and health care system costs," according to the letter.. Multiple nuclear medicine and cardiology groups-including SNMMI-published a joint statement in September expressing a similar sentiment. In it, the groups said the CMS decision to assume a 90% utilization rate for PET cameras needed to be "reconsidered." ...
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Continuous monitoring for carbon-monoxide in the assembly calibration, cold header, and screw machine departments of an automotive company using a portable detector shows the highest concentration to be 30 ppm in the assembly department, and the average concentration of 15 ppm in all four departments. No measurable concentrations of carbon-dioxide (124389), nitrogen- dioxide (10102440), or sulfur-
(13)N-ammonia PET as a measurement of hindlimb perfusion in a mouse model of peripheral artery occlusive disease. (13)N-ammonia PET as a measurement of hindlimb perfusion in a mouse model of peripheral artery occlusive disease
The Nitrogen-16 source supplies a gamma ray of a known amount of energy. Thus it can give SNO an absolute energy calibration. (Optical calibration gives a relative calibration. The two together allow us to understand the response of the SNO detector to the neutrino signal.) Nitrogen-16 beta decays to an excited state of Oxygen-16 which emits the 6.13 MeV gamma ray that SNO detects. The Nitrogen-16 source was built at Berkeley National Labs in California. The gas transport system to supply the Nitrogen 16 was built by Andre Hamer, a Queens graduate student now with the Los Alamos National Lab. The Queens group has been very active in analyzing the signal from this source. Below, we see Mark Boulay, a Queens graduate student inspecting the source. The red arrow at the top points to the umbilical, the cable which transports N-16 gas to and from the source and the electrical cables necessary to run the source. The green arrow at the bottom points to the region of the source inside of which the ...
The flow of formation waters in these strata is driven by gravity (topography) and erosional rebound, and is controlled by rock absolute permeability, gas generation and capillary pressure to gas (relative permeability). The gas content of the coal ... Show Abstract ...
By Sheng-Ping Wang, Dan Zhou, Zuliang Yao, Santhosh Satapati, Ying Chen, Natalie A. Daurio, Aleksandr Petrov, Xiaolan Shen, Daniel Metzger, Wu Yin, Andrea R. Nawrocki, George J. Eiermann, Joyce Hwa, Craig Fancourt, Corin Miller, Kithsiri Herath, Thomas P. Roddy, Deborah Slipetz, Mark D. Erion, Stephen F. Previs and David E. Kelley ...
AIM. To assess the functionality of congenital coronary artery fistulas (CAFs) using adenosine stress N-13-ammonia positron emission tomography computed tomography (PET-CT).. METHODS. Congenital CAFs were incidentally detected during coronary angiography (CAG) procedures in 11 adult patients (six males and five females) with a mean age of 64.3 years (range 41-81). Patients were collected from three institutes in the Netherlands. The characteristics of the fistulas (origin, pathway and termination), multiplicity of the origins and pathways of the fistulous vessels were assessed by CAG. Five patients underwent adenosine pharmacologic stress N-13-ammonia PET-CT to assess myocardial perfusion and the functional behavior of the fistula.. RESULTS. Eleven patients with 12 CAFs, 10 unilateral and one bilateral, originating from the left anterior descending coronary artery (n = 8), right coronary artery (n = 2) and circumflex (n = 2). All fistulas were of the vascular type, terminating into either the ...
There is intense controversy as to the mechanisms underlying chronic but reversible left ventricular (LV) ischemic dysfunction. The aim of this study was to investigate the physiology underlying this condition in a canine model of noninfarcted collateral-dependent myocardium. METHODS: Six mongrel dogs were instrumented with ameroid constrictors on the left circumflex and right coronary arteries and a partial occluder on the left anterior descending coronary artery. The animals were followed up for 6 mo. Every 6 wk, measurements of regional wall thickening (M-mode echo), myocardial blood flow ((13)N-ammonia PET), oxygen consumption ((11)C-acetate PET), and glucose uptake ((18)F-FDG PET) were obtained. After 6 mo, myocardial blood flow reserve (during adenosine infusion) and regional contractile reserve (during infusion of a low dose of dobutamine) were also investigated. RESULTS: Following ameroid implantation, regional thickening decreased in the posterior wall (to 34% +/- 13% of baseline; P , ...
Semantic Scholar extracted view of Effect of left ventricular hypertrophy on myocardial blood flow and ventricular performance in systemic hypertension. by Allen B. Nichols et al.
The commonest eruption styles of basaltic volcanoes involve Hawaiian lava fountaining or intermittent Strombolian explosions. We investigate the ways in which magma rise speed at depth, magma volatile content and magma viscosity control which of these eruption styles takes place. We develop a model of the degree of coalescence between gas bubbles in the magma which allows us to simulate the transition between the two extreme styles of activity. We find that magma rise speed is the most important factor causing the transition, with gas content and viscosity also influencing the rise speed at which the transition occurs. Counter to intuitive expectations, a decrease in gas content does not cause a transition from Hawaiian to Strombolian activity, but instead causes a transition to passive effusion of vesicular lava. Rather, a change from Hawaiian to Strombolian style requires a significant reduction in magma rise speed.. ...
Clinical Utility of N-13 Ammonia Cardiac PET Perfusion Imaging in the Assessment of Epicardial Coronary Lesions of Intermediate Range. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
High purity, low cost standard round Bismuth Telluride Sputter Targets * ~100% density * Low gas content * Dense and homogeneous Contact Us :Request for Custom Sizes & Target Bonding services
Regional perfusion therapy can be an option for treating metastases which are cancers that started in one part of the body and have spread to an adjacent part.
Page: 1/15 AVSNITT 1: IDENTIFIKASJON AV STOFFET/STOFFBLANDINGEN OG AV SELSKAPET/FORETAKET 1.1 Produktidentifikator REF MUSTER Produktnavn NucleoBond BA Sample (5) 1 x 125 ml G3 1 x 60 ml G4 1 x
Myocardial perfusion reserve (hyperemic divided by basal myocardial blood flow) describes vasodilator responsiveness of coronaryresistive vessels. The effect of aging and gender on myocardial perfusion reserve remains controversial. Methods: We studied 56 normal volunteers (21 women, 35 men; aged 50 +/- 20 yr, range 21-86 yr) with O-15-water PET to measure myocardial blood flow during basal and hyperemic stales with intravenous dipyridamole (0.56 mg/kg, n = 46) or adenosine (140 mu g/kg/min, n = 10). For comparative analysis, patients were grouped according to age: ,30 yr (n = 11), 30-49 yr (n = 18), 50-69 yr (n = 15) and greater than or equal to 70 yr (n = 12). Results: Overall, basal flow was 1.00 +/- 0.26 ml/min/g and hyperemic flow was 3.31 +/- 1.38 ml/min/g, resulting in a myocardial perfusion reserve of 3.38 +/- 1.35. There was an increase in basal flow with age (r = 0.45, p , 0.025), although hyperemic flow was only lower in patients greater than or equal to 70 yr, causing a significant ...
2011. López-Ruiz Heraclio,* Cortés-Hernández Mayra, Rojas- Lima Susana, Höpfl Herbert. Synthesis of nitrogen-, oxygen- and sulphur-containing tripodal ligands with a trimethylbenzene core. Journal of the Mexican Chemical Society, 55(3), 168-175. (2011). ...
This study was designed to examine the relationship between epicardial ST change (EpST) and regional myocardial blood flow (RMBF) following coronary occlusion and extent of myocardial infarction (MI) in awake dogs. Fifteen min and two hr after coronary occlusion simultaneous measurements of EpST and RMBF were made. Six days later histologic MI and RMBF were determined in transmural myocardial samples from each electrode site. Greatest ST elevation occurred at sites of greatest ischemia and MI. However, 15 min after occlusion 29% of sites with greater than 50% MI and 39% of sites with greater than 50% reduction in RMBF did not demonstrate ST elevation greater than 2 mV. There were poor correlations between EpST and MI (r = 0.59) and RMBF (r = 0.57). Comparable relationships were observed two hr after occlusion. In the present study, there were not close quantitative or qualitative relationships between EpST and MI or RMBF. A good correlation was observed between RMBF at two hr and MI (r = 0.89). ...
TY - JOUR. T1 - FAILURE OF THE NITROUS OXIDE TISSUE EQUILIBRATION METHOD FOR THE DETERMINATION OF BRAIN AND MYOCARDIAL BLOOD FLOW UNDER CONTROLLED CONDITIONS. AU - Reid, Michael A.. AU - Runciman, William B.. AU - McLean, Colin F.. AU - Mather, Laurence E.. PY - 1992. Y1 - 1992. N2 - 1. Two adult merino ewes were prepared with intravascular cannule for sampling aortic root blood, sagittal sinus blood and coronary sinus blood. 2. One week after preparation the animals were anaesthetized then ventilated with a gas mixture containing 10% nitrous oxide (N2O) for 60 min. Serial measurements of brain and myocardial blood flow were made using the N2O tissue equilibration method of Kety and Schmidt. 3. N2O failed to achieve matching arteriovenous blood concentration equality and saturation of the relevant tissues. Valid use of the Kety‐Schmidt method, therefore, could not be confirmed. 4. Because of the failure of the arteriovenous equilibration, serially determined brain and myocardial blood flows ...
Hydrocarbon gas in a sample is measured by a double beam detector responding to the transmission of absorption properties of the gas in response to applied radiation from a laser source. Monochromatic light from the laser source is split into two radiation beams, a sample path beam and a reference path beam, and directed to a radiation detector which sequentially responds to the reference energy and the sample energy. A difference in the absorption by the sample path energy with respect to the reference path energy produces two, different level, output signals from the detector. The sample energy signal and reference energy signal are respectively directed to a sample channel circuit and a reference channel circuit. Outputs from the individual circuits are amplified logarithmically and applied to inputs of a differential amplifier wherein the ratio of the sample signal to the reference signal produces a voltage for actuating a meter indicator. For a hydrocarbon gas content in a sample in excess of a
In humans, basal myocardial blood flow remains constant regardless of the severity of coronary-artery stenosis. However, during hyperemia, flow progressively decreases when the degree of stenosis is about 40 percent or more and does not differ significantly from basal flow when stenosis is 80 percen …
We supply a wide variety of cyclotron target materials including Water-18O and Nitrogen-15N2/Oxygen gas mix, and we maintain an inventory of the most frequently requested products for rapid delivery.
Question 7: For example, in a process called ________ a nitrogen-16 atom (7 protons, 9 neutrons) is converted to an oxygen-16 atom (8 protons, 8 neutrons) within a few seconds of being created. ...
When treating confined melanoma regional perfusion therapy can be a treatment option for tumors that are confined to a single organ or region of the body.

Purpose: Spinal cord stimulation (SCS) relieves angina pectoris in patients with ischemic heart disease, but its mechanisms of action remain incompletely understood. The goal of this study was to determine whether short-term SCS therapy improves myocardial blood flow (MBF) and myocardial flow reserve (MFR) in patients with myocardial ischemia.. Methods: The study group consisted of 18 patients (16 males) ageing 59 to 84 years who had severe stable angina pectoris (CCS class 3-4 in 70%) despite optimized medical therapy, evidence of myocardial ischemia in non-invasive testing, but not being amenable to further revascularization. All patients had three-vessel-disease and prior coronary artery bypass Surgery. Nine had prior myocardial infarction. Patients with recent MI or ejection fraction ,40% were excluded. Quantitative myocardial blood flow was measured with positron emission tomography (PET) and [15O]H2O during rest and adenosine stress before turning the SCS device on (baseline) and again ...
The treatment of patients with glioma depended on the nature of the lesion and on histological grade of the tumor. Positron emission tomography (PET) using 13N-ammonia (NH3), 11C-methionine (MET) and 18F-fluorodeoxyglucose (FDG) have been used to assess brain tumors. Our aim was to compare their diagnostic accuracies in patients with suspected cerebral glioma. Ninety patients with suspicion of glioma based on previous CT/MRI, who underwent NH3 PET, MET PET and FDG PET, were prospectively enrolled in the study. The reference standard was established by histology or clinical and radiological follow-up. Images were interpreted by visual evaluation and semi-quantitative analysis using the lesion-to-normal white matter uptake ratio (L/WM ratio). Finally, 30 high-grade gliomas (HGG), 27 low-grade gliomas (LGG), 10 non-glioma tumors and 23 non-neoplastic lesions (NNL) were diagnosed. On visual evaluation, sensitivity and specificity for differentiating tumors from NNL were 62.7% (42/67) and 95.7% (22/23) for
Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) is improving the diagnosis, staging and treatment monitoring of a variety of cancers in comparison to alternative noninvasive imaging modalities. However, detection of small lesions is limited by image resolution and low signal to noise ratio. While computer-aided detection algorithms based on static PET may assist visual detection of lesions, the temporal domain information loss in the static image could impair the detection of lesions. In addition, spatial features such as the shape and contrast of a lesion in static PET images are highly variable and difficult to characterize. Since the dynamics of tracer uptake (tracer radioactivity) are different for normal and malignant tissue, the temporal domain provides potentially important additional features for use in lesion detection.; This dissertation focuses on three challenges in the detection of lesions in dynamic PET: feature extraction, detector design and thresholding ...
Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) is improving the diagnosis, staging and treatment monitoring of a variety of cancers in comparison to alternative noninvasive imaging modalities. However, detection of small lesions is limited by image resolution and low signal to noise ratio. While computer-aided detection algorithms based on static PET may assist visual detection of lesions, the temporal domain information loss in the static image could impair the detection of lesions. In addition, spatial features such as the shape and contrast of a lesion in static PET images are highly variable and difficult to characterize. Since the dynamics of tracer uptake (tracer radioactivity) are different for normal and malignant tissue, the temporal domain provides potentially important additional features for use in lesion detection.; This dissertation focuses on three challenges in the detection of lesions in dynamic PET: feature extraction, detector design and thresholding ...
TY - JOUR. T1 - Importance of basal nitric oxide synthesis in regulation of myocardial blood flow. AU - Benyó, Zoltán. AU - Kiss, Gergely. AU - Szabo, Csaba. AU - Csáki, Csilla. AU - Kovách, Arisztid G.B.. PY - 1991/1/1. Y1 - 1991/1/1. N2 - Study objective - The aim was to investigate whether basal coronary vascular tone and myocardial perfusion depend upon endothelial nitric oxide (NO) synthesis.Design - Myocardial blood flow and vascular resistance of the left and right ventricles were studied before and after intravenous infusions of either NG-nitro-L-arginine (L-NA), a specific inhibitor of NO synthase, or L-arginine, the precursor of NO synthesis. Radiolabelled microspheres were used to study myocardial blood flow in small tissue sections.Experimental material - 14 anaesthetised male cats, weight 2.1-3.5 kg, were used.Measurements and main results - Measurements were made before and 15 and 40 min after L-NA treatment (30 mg·kg-1 bolus followed by 1 mg·kg-1·min-1 infusion; n=8), and ...
Caffeine decreases exercise-induced hyperemic MBF, resulting in a significant decrease in physiologic MFR. This is significantly more pronounced at high-altitude exposure, where resting flow significantly increases and hyperemic flow response is blunted significantly more by caffeine than at normoxia. Although the long-term effect of caffeine consumption on human health is the subject of an ongoing controversy (27,28), we have studied the acute impact of caffeine consumption on MBF and found no significant increase in resting MBF by caffeine during normoxia, in agreement with Bottcher et al. (13). By contrast, at hypoxia-with which resting MBF was higher than at normoxia, in line with our previous results (21)-we found an increase in resting MBF after caffeine. This may in part be explained by the fact that caffeine might stimulate local and systemic catecholamine release (7), adding to the hypoxia-induced sympathetic activation, which contributes importantly to the regulation of MBF ...
I think if you review the attached article in Post #2, you will see that some of the steps in the CNO cycles occur due to the spontaneous emission of positrons from unstable nuclei produced after fusion with a proton. This process occurs over a period of time (i.e., there is a measurable half-life associated with it), and it fits with the definition of radioactive decay as it is understood in non-stellar processes ...
OBJECTIVES. The aim of this study was to evaluate myocardial blood flow regulation in collateral-dependent myocardium of patients with coronary artery disease. BACKGROUND. Despite great clinical relevance, perfusion correlates of collateral circulation in humans have rarely been estimated by quantitative methods at rest and during stress. METHODS. Nineteen patients with angina and isolated occlusion of the left anterior descending (n = 14) or left circumflex (n = 5) coronary artery were evaluated. Using positron emission tomography and nitrogen-13 ammonia, we obtained flow measurements at baseline, during atrial pacing-induced tachycardia and after intravenous administration of dipyridamole (0.56 mg/kg body weight over 4 min). Flow values in collateral-dependent and remote areas were compared with values in 13 normal subjects. RESULTS. Flow at rest was similar in collateralized and remote myocardium (0.61 +/- 0.11 vs. 0.63 +/- 0.17 ml/min per g, mean +/- 1 SD), and both values were lower than ...
The conductivity requirements of USP water systems approximate the capability of double pass RO systems. On many feed waters, double pass RO will consistently produce the required conductivity. Gas content of the second pass permeate is typically the primary contributor to the on line measured conductivity. In most waters, carbon dioxide is the primary reactive gas that increases the measured conductivity. Carbon dioxide content of the second pass permeate can be reduced by increasing the pH of the feed water to the RO system. This will convert free carbon dioxide gas to bicarbonate ion that can be rejected by membranes. However, in applications where chloramines are present in the feed water, raising the pH will convert ammonium ions to free ammonia gas that will pass through the membranes and will contribute to the measured conductivity of the water. Adjusting the pH to be high for one pass and low for another can address the dual gas problem. Also the use of membrane degasification will ...
and other dissolved gases. The bellows pump was then used to pump the exsolved gases through the drying trap into a calibrated volume. After the pumping was completed, the total amount of gas was measured using a high precision capacitance manometer attached to the calibrated volume. Then splits of the dry gas were sealed into glass ampoules. For rare gas measurements, the ampoules were constructed of type 1720 or 1724 aluminosilicate glass with low helium permeability. During the 2004 R/V Thompson cruise, our extraction line had the capability of handling about 1.5 l of total gas, which proved to be inadequate for some of the very gassy vent fluid samples. Thus for most gas-rich samples it was necessary to carry out the extractions in multiple steps. While this provided an accurate assessment of total gas content, the multiple step extraction fractionated the samples, making them unsuitable for gas composition or isotopic measurements. For the 2005 R/V Natsushima cruise, the extraction line was ...
In this issue of iJACC, Dilsizian and Taillefer (1) offer a historical tour highlighting radiopharmaceutical developments for cardiac applications in nuclear medicine. This review features the staged developments in the field of nuclear cardiology from initial thallium-201 applications to the upcoming promise of the new F-18 agent, Flurpiridaz. As noted in this review, the data with positron emission (PET) and single-photon emission computed (SPECT) tomography has been unfolding over the past few years with more emphasis on prognosis (2,3), risk stratification with myocardial flow reserve (3,4), radiation dose reduction techniques (5), new cameras (6,7), new protocols (8), and, now, new isotopes (9-11). Basically, the whole field has revamped over the past few years! Todays practice of nuclear cardiology has little resemblance to the planar imaging days where images were indubitably described as unclear medicine. Clinical advances of fast speed, low-radiation exposure, and enhanced resolution ...
Air samples were analyzed for formaldehyde (50000), carbon-monoxide (630080), oxides of nitrogen (NO2/NO), ozone (10028156), nitrogen- dioxide (10102440) (NO2), and phosgene (75445) at the Historic Atlanta Local Development Company (HALDC) (SIC-8911), Atlanta, Georgia on August 17, 1979. The investigation request was made by the Director of HALDC to investigate three workers complaints of eye, no
Zheng QF, Xie RS, Fang LM, Cai ZY, Ma ZQ, Gong S. Oxygen- deficient and nitrogen- doped MnO2 nanowire- reduced graphene oxide- cellulose nanofibril aerogel electrodes for high- performance asymmetric supercapacitors. Journal of Materials Chemistry A. 2018 ;6:24407-24417. ...
Finally, we found that DC sensing of HIV-1 and HIV-2 required the DNA sensor cGAS. Treatment consisted of viagra without prescription two 35-day cycles of combination chemotherapy with CPT-11 and UFT. Nerve regression and sprouting were found in animals chronically paralysed with curare over several weeks as well as in untreated frogs (winter and summer frogs, laboratory frogs, fed and unfed). However, environmental change may also reconfigure multispecies interactions when both species composition and phenology remain intact. Arterial spin-labeling MR imaging is now acknowledged for the noninvasive quantification of cerebral blood flow.. Structural and functional basis for JAK3-deficient severe combined immunodeficiency. Person-mean centering was applied to psychological factors to disaggregate between- and within-individual association. In this experiment, we investigated the changes in serum levels of soluble RANKL (sRANKL), OPG, IL-6, and IL-6sR in patients with glucocorticoid-induced ...
TY - JOUR. T1 - Noninvasive quantification of airway inflammation following segmental allergen challenge with functional MR imaging. T2 - A proof of concept study. AU - Renne, Julius. AU - Hinrichs, Jan. AU - Schönfeld, Christian. AU - Gutberlet, Marcel. AU - Winkler, Carla. AU - Faulenbach, Cornelia. AU - Jakob, Peter. AU - Schaumann, Frank. AU - Krug, Norbert. AU - Wacker, Frank. AU - Hohlfeld, Jens M.. AU - Vogel-Claussen, Jens. PY - 2015/1/1. Y1 - 2015/1/1. N2 - Purpose: To evaluate oxygen-enhanced T1-mapping magnetic resonance (MR) imaging as a noninvasive method for visualization and quantification of regional inflammation after segmental allergen challenge in asthmatic patients compared with control subjects.Materials and After institutional review board approval, nine asthmatic Methods: and four healthy individuals gave written informed consent. MR imaging (1.5 T) was performed by using an inversion-recovery snapshot fast low-angle shot sequence before (0 hours) and 6 hours and 24 hours ...
Although dipyridamole produces coronary vasodilation, most reports on dipyridamole effects in animals have failed to show a change in CBF after intravenous infusion of dipyridamole.16 17 18 19 To our knowledge, this is the first study to quantitatively estimate the change in CBF in response to intravenous dipyridamole in humans. We found CBF values for the dipyridamole stress to be lower than those at rest (Table 2⇑ and Figure 2⇑). Dipyridamole stress also caused a significant reduction in Paco2 (Table 1⇑), and the vascular response to Paco2 change caused by the dipyridamole infusion closely followed the response due to hypocapnia (Table 2⇑ and Figure 1⇑). Thus, the decrease in CBF during dipyridamole stress can be explained by the decrease in Paco2 rather than the direct action of dipyridamole on CBF. The decrease in Paco2 during dipyridamole stress is most likely due to the hyperventilation side effect of adenosine.29 It has been reported that large doses of intravenous adenosine and ...
Now we get to the radioactive part. Put a teaspoonful of carbon-12 or carbon-13 on your kitchen table, and theyll stay right there for ever. They are stable isotopes. Even if you walk away and come back in a million years, there will still be exactly the same number of atoms on the table (unless youve had a fall of soot.) Carbon-14, however, is not like that. It is unstable, and spontaneously decays. Radioactive decay takes several forms but in this case each decay event causes a neutron to turn into a proton. The mass number thus remains 14, but the atomic number goes up one, and therefore that atom is no longer carbon. It becomes the next element in the table, which happens to be nitrogen. This decay process has a half-life of 5,730 years, so after that length of time half your carbon-14 has turned into nitrogen-14 and literally vanished into thin air. Nitrogen itself has one other stable isotope, nitrogen-15, plus a raft of unstable ones. Some of these decay back to carbon, some go on up to ...
Faster depletion of liquid hydrocarbons reserves makes coal bed methane a potential energy source. In the present investigation, coal samples were collected from a coal bed methane reservoir and proximate analysis was carried out to determine the ash content, volatile matter, and moisture content. Permeability and porosity of the coal was obtained to determine the gas content and flow characteristic of gas through the coal bed. Reserve and recoverable gas from the coal bed methane field under study was estimated from the adsorption-desorption experiments and simulation study. Future production rate of gas and water and dewatering time were predicted using Fekete coal bed methane software ...
The dynamic nature of cardiac ischemia is reflected in the concept of coronary flow reserve (CFR), first proposed by Gould in 1974. CFR is a measure of the degree to which the coronary circulation is able to increase myocardial blood flow when the perfusion bed is maximally dilated. Normal values of CFR vary by age and sex but are typically in the range of 3-4; CFR values less than 2 are generally pathologic and associated with ischemia/infarction. Contrast-enhanced MRI performed at rest and under pharmacologic stress does not measure CFR directly, but a closely related quantity, myocardial flow reserve (MFR). Like CFR, MFR has been shown to be an important predictor for future coronary events in patients with coronary artery disease and outcomes after revascularization or stenting ...
The Cosmic Web harbours a range of structures and densities: at one extreme one finds galaxy clusters, the most massive, virialized dense conglomerates of thousands of galaxies, and at the other extreme there are the voids, occupying most of the volume in the universe with sizes in the range of 20-50 h^-1 Mpc, sparsely filled with an occasional galaxy or small group. As the evolutionary timescale in voids is long and extreme processes related to high galaxy density (ram pressure and tidal stripping for example) presumably absent, voids are ideal pristine environments to study galaxy structure and evolution. The Void Galaxy Survey has this aim and in this talk I present the results we obtained thus far from a multiwavelength study comprising UV, optical, Halpha, NIR and HI imaging of 60 void galaxies chosen from a sample of 250 void galaxies selected from the SDSS. I will address morphology, star formation properties, and gas content and make a comparison with similar size galaxies in other ...