1,721,001 research outputs found
The effects of general anaesthesia on heart rate variability during abdominal surgery
No full textWe aimed to realized a pilot study that investigated heart rate variability (HRV) during anesthesia to study of alterations in the autonomous function and study the effects of anesthetic drugs with a not invasive test. We studied 15 subjects of both sexes (9 women and 6 men) with a mean age of 53.6 ± 14.3 years. ECG signal recording, lasting 5 minutes each, in three times: First time, the registration before anaesthesia. The second was performed after anaesthesia induction and after 5 minutes after the start of maintenance. The third measurement was performed 24 hours after surgery. The mean heart rate did not show significant alterations during anesthesia and after 24 hours of surgery compared with baseline. On the contrary, the indices of heart rate variability in the frequency domain showed significant variations during general anesthesia. In fact there was a significant decrease in LF, expressed in normalized units and at the same time a significant increase in HF, always expressed in normalized units. It follows that the LF / HF ratio has been significantly reduced during the period of anesthesia. All indices are nearly returned to baseline after 24 hours of surgery. The analysis of anesthetic effects on HRV may provide a more valuable noninvasive tool for investigating alterations in autonomic function. Anesthetics used in general anesthesia suppress the autonomic nervous system and contribute to the safety of general anesthesia not only because suppress the excessive sympathetic activity caused by the operation but also because suppress parasympathetic reactions. The attenuation of sympathetic activity during general anesthesia is usually assessed by measuring changes in blood pressure or heart rate. In all cases, because of these antagonistic effects, evaluation becomes problematic when parasympathetic activity is simultaneously depressed.We aimed to realized a pilot study that investigated heart rate variability (HRV) during anesthesia to study of alterations in the autonomous function and study the effects of anesthetic drugs with a not invasive test. We studied 15 subjects of both sexes (9 women and 6 men) with a mean age of 53.6 ± 14.3 years. ECG signal recording, lasting 5 minutes each, in three times: First time, the registration before anaesthesia. The second was performed after anaesthesia induction and after 5 minutes after the start of maintenance. The third measurement was performed 24 hours after surgery. The mean heart rate did not show significant alterations during anesthesia and after 24 hours of surgery compared with baseline. On the contrary, the indices of heart rate variability in the frequency domain showed significant variations during general anesthesia. In fact there was a significant decrease in LF, expressed in normalized units and at the same time a significant increase in HF, always expressed in normalized units. It follows that the LF / HF ratio has been significantly reduced during the period of anesthesia. All indices are nearly returned to baseline after 24 hours of surgery. The analysis of anesthetic effects on HRV may provide a more valuable noninvasive tool for investigating alterations in autonomic function. Anesthetics used in general anesthesia suppress the autonomic nervous system and contribute to the safety of general anesthesia not only because suppress the excessive sympathetic activity caused by the operation but also because suppress parasympathetic reactions. The attenuation of sympathetic activity during general anesthesia is usually assessed by measuring changes in blood pressure or heart rate. In all cases, because of these antagonistic effects, evaluation becomes problematic when parasympathetic activity is simultaneously depressed
Microstructures as Models for Origin of Life in Hot Water: Hydrogen-Assisted Self-Assembly of Glycine and Alanine Zwitterions
No full textBuilding on the early investigation by Sidney W. Fox that dry-heated amino acids can spontaneously form microspheres, this research studies the self-organization of glycine and alanine with hydrogen in a liquid system. This study aimed to investigate the spontaneous formation of membraneless, microscale amino acid assemblies under simulated prebiotic hydrothermal conditions, such as hot mineral sources and ponds. Aqueous solutions of glycine and alanine were prepared in a hydrogen-rich mineral buffer and thermally incubated at 75 °C. Phase-contrast microscopy, transmission electron microscopy (TEM), and molecular modeling were employed to analyze the morphology and internal organization of the resulting structures. Microscopy revealed that zwitterionic glycine and alanine spontaneously self-organize into spherical microspheres (~12 µm), in which the charged –NH3+ and –COO− groups orient outward, while the hydrophobic methyl groups of alanine point inward, forming a stabilized internal core. The primary studies were performed with hot mineral water from Rupite, Bulgaria, at 73.4 °C. The resulting osmotic pressure difference Δπ ≈ 2490 Pa, derived from the van’t Hoff equalization. This suggests a chemically asymmetric system capable of sustaining directional water flux and passive molecular enrichment. The zwitterionic nature of glycine and alanine, which possesses both –NH3+ and –COO− groups, supports the formation of microspheres in our experiments. Under conditions with hot mineral water and hydrogen acting as a reducing agent in the primordial atmosphere, these amino acids self-organized into dense interfacial microspheres. These findings support the idea that thermally driven, zwitterion-mediated aggregation of simple amino acids, such as glycine and alanine, with added hydrogen, could generate membraneless, selectively organized microenvironments on the early Earth. Such microspheres may represent a plausible intermediate between dispersed organisms and microspheres
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Influence of the contact roughness upon railway monobloc wheel acoustic behaviour on virtual prototyping approach
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
THE INTERNATIONAL EVENT “DAYS OF MOUNTAIN WATER”, TETEVEN, BULGARIA, MICROBIOLOGICAL AND PHYSICOCHEMICAL RESEARCH OF MOUNTAIN SPRING WATER
No full textIn Bulgaria there are the following mountains – Stara Planina (Balkan), Rila, Pirin, Rodope etc. The name of the Balkan Peninsula is from the old name of the mountain Stara Planina – Balkan. In Bulagria there are 139 peaks more than 2000 m above sea level. The biggest peak in Balkan Peninsula is Mousala (2925 m). Teteven municipally has big part of Stara planina mountain with the highest peak Vezhen (2198 m).
The event “Days of mountain water” is one of a kind in Bulgaria. It takes place on 11th June and lasts for several days in the Municipality of Teteven, Bulgaria. Its beginning dates from 2010, and it is a joint undertaking between Ignat Ignatov, Scientific Research Center of Medical Biophysics and Municipality of Teteven, Bulgaria.
The event is connected with research of microbiological and physicochemical parameters of mountain spring waters from Municipality of Teteven, Bulgaria. The applied spectral method is „NES“. The analyses show the optimum quantity among the minerals of Calcium (Са2+), Magnesium (Mg2+), Potassium (K+), Sodium (Nа+), Manganese (Mn2+) and Zinc (Zn2+) that provide the right balance in the human body for health and longevity.
Considered is the history of the event and what is achieved by the organizers. The emphasis is on the main objectives set out by the event, and the accomplished tasks for its successful delivering. Representatives of 15 states have participated in it – Bulgaria, Austria, Germany, Switzerland, Russia, USA, France, Israel, Czech Republic, Denmark, Turkey, Greece, Hungary and Serbia.
A survey was conducted regarding the event “Days of mountain water” in the Facebook group “Teteven Balkan”. 66 people responded on a random basis. The aim of the survey was the people to estimate how useful stay in Teteven municipality is.
In the present article are listed in more detail the natural assets of municipal area of Teteven, located in “Fore-Balkan” in the central part of Stara planina Balkan range. The possibilities are shown for development of tourism in the region, its particular characteristics and specific features. Analyzed are the water resources, the mountain water as a factor for health and longevity. The information helps for development of tourism in the region. Described are the springs and fountains of mountain water in Teteven and its surrounding municipal areas. It is conducted quantitative and qualitative analysis of the chemical and physical parameters of the springs. On six of the springs are placed information signs about the chemical composition, physical parameters and properties relating to health
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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