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22782. The real symmetric matrices of odd order with a P-set of maximum size
- Creator:
- Du, Zhibin and da Fonseca, Carlos M
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- matematika, mathematics, real symmetric matrix, graph, multiplicity of eigenvalues, P-set, P-vertices, 13, and 51
- Language:
- English
- Description:
- Suppose that A is a real symmetric matrix of order n. Denote by m_{A}(0) the nullity of A. For a nonempty subset α of {1, 2,..., n}, let A(α) be the principal submatrix of A obtained from A by deleting the rows and columns indexed by α. When m_{A(\alpha )}(0) = m_{A}(0)+|α|, we call α a P-set of A. It is known that every P-set of A contains at most \left \lfloor n/2 \right \rfloorelements. The graphs of even order for which one can find a matrix attaining this bound are now completely characterized. However, the odd case turned out to be more difficult to tackle. As a first step to the full characterization of these graphs of odd order, we establish some conditions for such graphs G under which there is a real symmetric matrix A whose graph is G and contains a P-set of size (n − 1)/2., Zhibin Du, Carlos M. da Fonseca., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
22783. The realization of strong, stray static magnetic fields
- Creator:
- Žežulka, Václav and Pavel Straka
- Format:
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, magnetické obvody, magnetic circuits, static magnetic fields, permanent NdFeB magnets, 7, and 551
- Language:
- English
- Description:
- The article introduces the results achieved in the creation of feasible assemblies of NdFeB magnets assembled following an already published design of a practical arrangement of magnets derived from an ideal magnetization pattern, leading to the strongest possible stray field at a remote point. It presents a method of the implementation of these assembled sets and the relevant measured dependences of magnetic induction By = f(y) and By = f(x) including their comparison with already published dependences determined by a simulation. It further presents similar dependences of magnetic induction found in the case of a trial magnetic circuit with large blocks from NdFeB magnets, and these dependences are compared both with the mentioned computer-determined dependences and the dependences measured with the corresponding implemented assembly of magnets., Václav Žežulka and Pavel Straka., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
22784. The Reception on the Oeuvre of Composers Active at the Court of Rudolf II in Prague in the Contemporaneous Musical Repertoire of Historical Upper Hungary
- Creator:
- Marta Hulková
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- Type:
- article, články, model:article, and TEXT
- Subject:
- II. Habsburský, římskoněmecký císař, Rudolf, 1552-1612, 1576-1611, muzikologie, musicology, dějiny hudby, history of music, hudební skladatelé, composers, archivní fondy, archives, hudební rukopisy, music manuscripts, Slovensko, Slovakia, 78.01, 78(091), 78.071.1, 930.253, 091:78, and (046)
- Language:
- Czech
- Description:
- Studie Marty Hulkové se zabývá rozšířením repertoáru hudební skladatelů na pražském dvoře císaře Rudolfa II. v historickém prostoru Horních Uher v době jeho vlády., Marta Hulková., Rubrika: Studie, and Slovenské resumé na s. 157, anglický abstrakt na s. 133.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
22785. The relationship between antioxidant enzymes and lipid peroxidation in senescent rat erythrocytes
- Creator:
- Mladenov, M., Gokik, M., Hadzi-Petrushev, N., Gjorgoski, I., and Jankulovski, N.
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, kyselina močová, uric acid, D-galactose, antioxidant enzymes, melondialdehyde, rats, 14, and 612
- Language:
- English
- Description:
- The aim of this study was to gain more complete information about the relationships between some endogenous antioxidants and the malondialdehyde (MDA) as a marker of lipid peroxidati on, during D -galactose induced senescence. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and the concentrations of uric acid (UA) in plasma and MDA in erythrocyte’s hemolysate, were determined in 15 D -galactose (D-gal), treated rats and compared with 15 placebo. The activity of the erythrocyte’s CAT was found significantly increased due to the senescence. The ratio of the activities of antioxidant enzymes R =SOD/(GPx+CAT) was significantly decreased due to the sen escence and negatively correlated with the MDA ( ρ = -0.524, p=0.045). The antioxidant enzymes SOD and GPx negatively correlated with the MDA, while CAT displayed no correlation. Further, the UA positively correlated with the ratio of activities of the antioxidant enzymes R=SOD/(GPx+CAT), ( ρ =0.564, p=0.029 for senescent rats). Obtained results may contribute t o better understanding of the process of D-gal induced senescence in the erythrocytes., M. Mladenov, M. Gokik, N. Hadzi-Petrushev, I. Gjorgoski, N. Jankulovski., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
22786. The Relationship Between Episodic Memory and Context: Clues from Memory Errors Made While Under Stress
- Creator:
- Lynn Nadel and Payn, J.D.
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- Type:
- article, studie, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, 14, and 612
- Language:
- English
- Description:
- a1_In a series of studies in the late 1950s and early 1960s, Jan Bures introduced cortical spreading depression to the field of behavioral neuroscience (eg. Bures 1960). This technique offered a unique way to study the role of cortex in learning and memory, and attracted the attention of many who began their graduate studies at that time, including one of us (LN, cf. Nadel 1966). An NIH postdoctoral fellowship to study with the master himself brought LN to Prague in September 1967. Thus began a relationship that included science, politics, and personal life, and has lasted over 30 years1,2. The first scientific exchange began with Jan pulling a piece of paper from his desk with a long list of possible experiments written on it -- “pick one”, he said. This led to a series of studies on interhemispheric transfer of learning under conditions of monocular input, demonstrating, amongst other things, that such transfer is not a uniform process. Depending on the kind of trials given with both hemispheres intact, and the eye which remained open to input, transfer can either be non-specific, likely involving some kind of procedural knowledge, or highly specific, likely involving knowledge about the trained discrimination itself (Nadel and Buresova, 1970). These studies anticipated LN’s future work on multiple memory systems, a research enterprise pursued in the following decades by many labs (including LN’s: e.g. Nadel and O’Keefe 1974, O’Keefe et al. 1975). In this paper we focus on several scientific issues that Jan has been thinking about for the past 25 years. In particular, we consider spatial learning, the hippocampus, and memory. To this mix we add stress, something well known to anyone living in Prague in 1968., a2_LN left Prague after the 1968 invasion and stayed in London for seven months, during which time arrangements were made for an eventual return to the Medical Research Council Cerebral Functions Research Group in 1970. Thus it was that LN happened to be down the hall when John O’Keefe and Jonathan Dostrovsky discovered place cells (O’Keefe and Dostrovsky 1971) and began the program of research leading to the cognitive map theory of hippocampal function (O’Keefe and Nadel 1978)., L. Nadel, J.D. Payne., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
22787. The relationship between glycemia, insulin and oxidative stress in hereditary hypertriglyceridemid rat
- Creator:
- Michal Žourek, Pavlína Kyselová, Jiří Mudra, Michal Krčma, Zdeněk Jankovec, Silvie Lacigová, Jakub Víšek, and Zdeněk Rušavý
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Biochemie. Molekulární biologie. Biofyzika, diabetologie, oxidační stres, inzulín, potkan, diabetology, oxidative stress, insulin, Rattus norvegicus, clamp, 2, and 577
- Language:
- English
- Description:
- The aim of this study was to determine the effects of insulin infusion on oxidative stress induced by acute changes in glycemia in non-stressed hereditary hypertriglyceridemic rats (hHTG) and Wistar (control) rats. Rats were treated with glucose and either insulin or normal saline infusion for 3 hours followed by 90 min of hyperglycemic (12 mmol/l) and 90 min of euglycemic (6 mmol/l) clamp. Levels of total glutathione (GSH), oxidized glutathione (GSSG) and total antioxidant capacity (AOC) were determined to assess oxidative stress. In steady states of each clamp, glucose infusion rate (GIR) was calculated for evaluation of insulin sensitivity. GIR (mg.kg-1.min-1) was significantly lower in hHTG in comparison with Wistar rats; 25.46 (23.41 - 28.45) vs. 36.30 (27.49 - 50.42) on glycemia 6 mmol/l and 57.18 (50.78 - 60.63) vs. 68.00 (63.61 - 85.92) on glycemia 12 mmol/l. GSH/GSSG ratios were significantly higher in hHTG rats at basal conditions. Further results showed that, unlike in Wistar rats, insulin infusion significantly increases GSH/GSSG ratios in hHTG rats: 10.02 (9.90 - 11.42) vs. 6.01 (5.83 - 6.43) on glycemia 6 mmol/l and 7.42 (7.15 - 7.89) vs. 6.16 (5.74 - 7.05) on glycemia 12 mmol/l. Insulin infusion thus positively influences GSH/GSSG ratio and that way reduces intracellular oxidative stress in insulin-resistant animals., M. Žourek, P. Kyselová, J. Mudra, M. Krčma, Z. Jankovec, S. Lacigová, J. Víšek, Z. Rušavý., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
22788. The relationship between gneisses from the Kola Superdeep Borehole and their surface analogues
- Creator:
- Jiřina Trčková, Vladimír Šrein, Šťastný, Martin, and Roman Živor
- Format:
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, ruly, gneiss, Kola superdeep borehole, surface analogues, 7, and 551
- Language:
- English
- Description:
- Modal composition and grain-size characteri stics, physical and mechanical propertie s of three samples of Archean gneisses of the Kola series from the depths of 6.8 to 8.4 km of the Kola Superdeep Borehole (KSDB-3) and two collections of their surface analogues were analysed. On the basis of a comparison of the petrographic characteristics of the borehole samples and analogues, it was found that not all analogues are equivalents of corresponding core samples completely. Mechanical properties of core samples are affected by depth of the core sample position in the borehole. This work forms part of the research in the frame of the INTAS Project No.314 "Geodynamics in the cross-section of the Kola superdeep"., Jiřina Trčková, Vladimír Šrein, Martin Šťastný and Roman Živor., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
22789. The relationship between iodine intake and serum thyroglobulin in the general population
- Creator:
- Radovan Bílek, Jarmila Čeřovská, and Václav Zamrazil
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- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, jod, toleranční meze, iodine, tolerance limits, thyroglobulin, population studies, normal individuals, 14, and 612
- Language:
- English
- Description:
- The relationship is shown between a concentration of urinary iodine and serum thyroglobulin in population studies carried out on a general population that was randomly selected from the registry of the General Health Insurance Company (individuals aged 6-98 years, 1751 males, 2420 females). The individuals were divided into subgroups with a urinary iodine concentration of <50, 50-99, 100-199, 200-299 and ≥300 μg/l. The mean and median of thyroglobulin were calculated in these subgroups. Tg concentrations were dependent on gender (males<females), age (thyroglobulin increased with age) and statistically significant negative relationship was observed between thyroglobulin and urinary iodine in individuals with urinary iodine <300 μg/l and the age under 65 years. Upper nonparametric tolerance limits of thyroglobulin in relation to iodine intake were calculated in subgroup of normal individuals (n=1858, thyroglobulin, urinary iodine, thyrotropin and free thyroxine were within the normal reference range). Upper limits were dependent on gender and age. The total value of upper limits is 44 μg/l; for individuals aged 6-17 years it is 39.1 μg/l; 18-65 years = 51.4 μg/l and 66-98 years = 60.6 μg/l. In general, thyroglobulin serum concentrations higher than 40 μg/l should be an indicator for determining urinary iodine., R. Bílek, J. Čeřovská, V. Zamrazil., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
22790. The Relationship Between the IGF-I System and Its Binding Proteins and Microvascular Reactivity in Type 1 Diabetes Mellitus
- Creator:
- Michal Kršek, Martin Prázný, Jan Škrha, Vlasta Justová, Zdeňka Lacinová, and Tomáš Haas
- Format:
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- Type:
- article, studie, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, IGF-I, IGFBP-1, Microangiopathy, IDDM, Laser-Doppler flowmetry, 14, and 612
- Language:
- English
- Description:
- The system of IGF-I and its binding proteins may be involved in the pathogenesis of vascular damage in Type 1 diabetes. The aim of this study was to analyze the relationship between this system and the microvascular reactivity in Type 1 diabetes as measured by laser-Doppler flowmetry. Twenty-two Type 1 diabetic patients (13 women and 9 men) with microangiopathy and fifteen healthy subjects (8 women and 7 men) were examined clinically, underwent laser-Doppler flowmetry and intima-media thickness measurements. Fasting serum levels of IGF-I, free IGF-I, IGFBPs and lipids were examined. The microvascular reactivity was impaired in Type 1 diabetic patients. Maximal perfusion during post-occlusive reactive hyperemia (PORHmax) and during thermal hyperemia (THmax) was significantly decreased in Type 1 diabetes (p<0.01). Percentage perfusion increase in both tests (PORH and TH) was lower in Type 1 diabetes mellitus (p<0.01) and the reaction after heating was slower in diabetic patients (THmax/t) (p<0.01). We did not find any significant dependence of microvascular reactivity on the parameters of IGF-I or its binding proteins. We conclude that the microvascular reactivity is impaired in Type 1 diabetes mellitus, but this impairment is not clearly dependent on the activity of the IGF-I system. It is probably only a complementary pathogenic factor., M. Kršek, M. Prázný, J. Škrha, V. Justová, Z. Lacinová, T. Haas., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public