62,896 research outputs found
Systemic oxygen extraction during exercise at high altitude
No full textBackgroundClassic teaching suggests that diminished availability of oxygen leads to increased tissue oxygen extraction yet evidence to support this notion in the context of hypoxaemia, as opposed to anaemia or cardiac failure, is limited.MethodsAt 75 m above sea level, and after 7–8 days of acclimatization to 4559 m, systemic oxygen extraction [C(a?v)O2] was calculated in five participants at rest and at peak exercise. Absolute [C(a?v)O2] was calculated by subtracting central venous oxygen content (CcvO2) from arterial oxygen content (CaO2) in blood sampled from central venous and peripheral arterial catheters, respectively. Oxygen uptake (V.O2) was determined from expired gas analysis during exercise.ResultsAscent to altitude resulted in significant hypoxaemia; median (range) SpO2 87.1 (82.5–90.7)% and PaO2 6.6 (5.7–6.8) kPa. While absolute C(a?v)O2 was reduced at maximum exercise at 4559 m [83.9 (67.5–120.9) ml litre?1 vs 99.6 (88.0–151.3) ml litre?1 at 75 m, P=0.043], there was no change in oxygen extraction ratio (OER) [C(a?v)O2/CaO2] between the two altitudes [0.52 (0.48–0.71) at 4559 m and 0.53 (0.49–0.73) at 75 m, P=0.500]. Comparison of C(a?v)O2 at peak V.O2 at 4559 m and the equivalent V.O2 at sea level for each participant also revealed no significant difference [83.9 (67.5–120.9) ml litre1 vs 81.2 (73.0–120.7) ml litre?1, respectively, P=0.225].Conclusion In acclimatized individuals at 4559 m, there was a decline in maximum absolute C(a?v)O2 during exercise but no alteration in OER calculated using central venous oxygen measurements. This suggests that oxygen extraction may have become limited after exposure to 7–8 days of hypoxaemia
Cardiopulmonary exercise testing for the evaluation of perioperative risk in non-cardiopulmonary surgery
No full textThe use of cardiopulmonary exercise testing (CPET) as a preoperative risk stratification tool for a range of non-cardiopulmonary surgery is increasing. The utility of CPET in this role is dependent on the technology being able to identify accurately and reliably those patients at increased risk of perioperative events when compared with existing risk stratification tools. This article identifies and reviews systematically the current literature regarding the use of CPET as a preoperative tool for stratifying risk in major non-cardiopulmonary surgery. Specifically, it focuses on evaluating the capacity of CPET variables to predict the risk of postoperative complications and mortality in comparison to other methods of risk assessment. Furthermore, the potential for combining results from CPET and non-CPET methods of risk prediction to enhance the capacity to identify high risk patients is considered. The review indicates that CPET can identify patients at increased risk of adverse perioperative outcomes. However, the selection of variables and threshold values to indicate high risk differ for different surgical procedures and underlying conditions. Furthermore, the available data suggest that CPET variables outperform alternative methods of preoperative risk stratification. Several studies also identify that CPET variables may be used in combination with non-CPET variables to increase perioperative risk prediction accuracy. These findings illustrate that CPET has the capacity to identify patients at increased risk of adverse outcome before a range of non-cardiopulmonary surgical procedures. Further research is required to optimise its use, potentially by combining CPET results with alternative methods of risk stratification
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Stable voters in an unstable party environment : continuity and change in Italian electoral behaviour
No full textM.24981-1999 Paolo Segatti, Paolo Bellucci and Marco Maraffi. 30 cm. A previous version of this paper was presented at a symposium on Political Parties : Changing Roles in Contemporary Democracies, held at the Center for Advanced Study in the Social Sciences of the Juan March Institute, Madrid, December 15-17, 1994. -- P.1. Includes bibliographical references (p. 56-59
De Maiestate / Praeside M. Jacobo Thomasio, Moralis Philosoph. P. P., publice disputabit Johannes Dunte, R. L. Author & Respon: ad diem 9. Septembr. H L. Q. C.
No full textDE MAIESTATE / PRAESIDE M. JACOBO THOMASIO, MORALIS PHILOSOPH. P. P., PUBLICE DISPUTABIT JOHANNES DUNTE, R. L. AUTHOR & RESPON: AD DIEM 9. SEPTEMBR. H L. Q. C.
De Maiestate / Praeside M. Jacobo Thomasio, Moralis Philosoph. P. P., publice disputabit Johannes Dunte, R. L. Author & Respon: ad diem 9. Septembr. H L. Q. C. (1)
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Beiträge (21
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Diagnostic performance of P wave duration in the identification of left atrial enlargement in dogs
No full textObjectives: To determine sensitivity and specificity of P wave duration in the identification of left atrial enlargement (LAE) in dogs.
Methods: Electrocardiograms (ECG) from normal dogs and dogs with various cardiovascular diseases were evaluated. Inclusion criteria were the availability of an ECG showing a stable isoelectric line, easily recognizable P waves and good quality 2D echocardiographic estimate of left atrial dimensions using the left atrial to aortic root ratio (LA/Ao).
Using a metal caliper system, P wave duration was measured to the nearest 10 msec for six consecutive heart beats; data were then averaged for each dog. The accuracy of P wave duration in predicting LAE was determined using a Receiver Operating Characteristic (ROC) analysis.
Results: 156 dogs were included in the study. Average P wave durations of 20, 30, 40 and 50 msec yielded sensitivities of 100%, 85%, 68% and 40% and specificities of 0%, 16.04%,
64.15% and 93.4%, respectively, for the diagnosis of LAE by echocardiography. The estimated Area Under Curve (AUC) of the ROC curve was 0.70 (95% confidence interval: 0.60-0.80).
Clinical significance: The diagnostic performance of P wave duration for identification of LAE in dogs presents considerable limitations
The long-wavelength view of GG Tau A: rocks in the ring world
No full textWe present the first detection of GG Tau A at centimetre wavelengths, made with the Arcminute Microkelvin Imager Large Array at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at >6 σrms with an integrated flux density of S16GHz = 249 ± 45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long-wavelength tail of the dust emission from this unusual protoplanetary system. We use an MCMC-based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of Md ~ 0.1 Msun, constrain the dimensions of the emitting region and find that the opacity index at λ > 7 mm is less than unity, implying a contribution to the dust population from grains exceeding ~4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association in combination with the low derived disc mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models
Cardiopulmonary exercise testing predicts postoperative outcome in patients undergoing gastric bypass surgery
No full textAT, determined using CPET, predicts LOS after gastric bypass surgery
Art battle diorama in military-historical museums of USSR and CIS in the second half of 20th century
No full textGorbunov, I. V. Art battle diorama in military-historical museums of USSR
and CIS in the second half of 20th century : monograph / I. V. Gorbunov ; The Ministry of education of the Repablic of Belarus, Educational establishment "Vitebsk State P. M. Masherov University", Chair desing, and crafts and technical graphics. - Vitebsk : Vitebsk State P. M. Masherov University, 2009. - 164 p. : il. - Bibliogr.: p. 99-110. - Biographical dictionary: p. 111-119. - Chronology of development of diorama art (1929-1995): p. 122-132.The monograph represent a complex study of the domestic school Museum and exhibition desing of military-historical museums as art form a complex diorama occupies a dominant place. On the rich illustrative material, the author shows all parties forming dioramas. Gradually, all the elements are investigated artwork, such as modelling-layout plan, lighting, monumental painting, which form the diorama as a complex Museum and exhibition complex-ensemble with 1948 po 1995 gg. intended for researchers, muzeevedov, students of art majors, anyone interested in issues of design and creating monumental-decorative registration of exhibitions and museums
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