12 research outputs found
Synchronization of networks with prescribed degree distributions
No full textSFI Working Papers contain accounts of scientific work of the author(s) and do not necessarily represent the views of the Santa Fe Institute. We accept papers intended for publication in peer-reviewed journals or proceedings volumes, but not papers that have already appeared in print. Except for papers by our external faculty, papers must be based on work done at SFI, inspired by an invited visit to or collaboration at SFI, or funded by an SFI grant. ©NOTICE: This working paper is included by permission of the contributing author(s) as a means to ensure timely distribution of the scholarly and technical work on a non-commercial basis. Copyright and all rights therein are maintained by the author(s). It is understood that all persons copying this information will adhere to the terms and constraints invoked by each author's copyright. These works may be reposted only with the explicit permission of the copyright holder. www.santafe.ed
Graphs with given degree sequence and maximal spectral radius
No full textWe describe the structure of those graphs that have largest spectral radius in the class of all connected graphs with a given degree sequence. We show that in such a graph the degree sequence is non-increasing with respect to an ordering of the vertices induced by breadth-first search. For trees the resulting structure is uniquely determined up to isomorphism. We also show that the largest spectral radius in such classes of trees is strictly monotone with respect to majorization. This paper is the revised final version of the preprint no. 35 of this research report series. (author´s abstract)Series: Research Report Series / Department of Statistics and Mathematic
Gaucher’s disease with valvular, myocardial and aortic involvement in a patient with oculomotor apraxia
No full textEvaluation of Vascular Endothelial Growth Factor Levels and Serum Angiotensin-Converting Enzyme Activity in Hyperlipidemia and Coronary Artery Disease
No full textAlgebraic Connectivity and Degree Sequences of Trees
No full textWe investigate the structure of trees that have minimal algebraic connectivity among all trees with a given degree sequence. We show that such trees are caterpillars and that the vertex degrees are non-decreasing on every path on non-pendant vertices starting at the characteristic set of the Fiedler vector. (author´s abstract)Series: Research Report Series / Department of Statistics and Mathematic
Largest Laplacian Eigenvalue and Degree Sequences of Trees
No full textWe investigate the structure of trees that have greatest maximum eigenvalue among all trees with a given degree sequence. We show that in such an extremal tree the degree sequence is non-increasing with respect to an ordering of the vertices that is obtained by breadth-first search. This structure is uniquely determined up to isomorphism. We also show that the maximum eigenvalue in such classes of trees is strictly monotone with respect to majorization. (author´s abstract)Series: Research Report Series / Department of Statistics and Mathematic
Association of heart rate profile during exercise with the severity of coronary artery disease
No full textArtykuł oryginalnyZwiązek pomiędzy otyłością a drożnością tętniczych pomostów wieńcowych w obserwacji odległej
No full textBackground: Arterial conduits having long-term patency rates have been increasingly used for bypass of coronary arteries although some risk factors for their occlusion such as recipient vessel size, older age, and hyperlipidaemia have been described. Obesity, on the other hand, has been well established as a coronary risk factor. However, the effects of obesity on patency of arterial conduits, especially the internal mammary artery, have not been studied previously. Aim: To assess the long-term effects of obesity on left internal mammary artery (LIMA) patency. Methods: Angiograms of all patients with a LIMA conduit only were analysed. Two groups were formed according to the LIMA patency: group 1 – patients with occluded LIMA (n = 59), and group 2 – patients with patent LIMA (n = 68). Baseline demographic, haemodynamic, and laboratory characteristics of patients in both groups were compared. Obesity was defined as body mass index ł 30 kg/m2. Results: The mean BMI value in group 1 was significantly higher than in group 2 (30.4 ± 3.1 vs. 28.7 ± 4.7, p = 0.025). The two groups differed in time from surgery, drug use, and HDL cholesterol level. In addition, patients in both groups were categorised by BMI, and obese and non-obese groups were formed. Higher BMI was significantly associated with LIMA occlusion such that 71% of patients in group 1 had increased BMI, compared with 25% of patients in group 2 (p < 0.001). Multivariate analysis showed that multiple adjusted OR of the risk of LIMA occlusion was 7.41 (95% CI 3.38-16.28) for patients with increased BMI. Conclusions: : Obesity (ł 30 kg/m2) has a significant and independent negative effect on the patency of the LIMA graft.Wstęp: Z uwagi na wysoki odsetek zachowanej po wielu latach drożności pomosty tętnicze są preferowanym sposobem wykonywania operacji rewaskularyzacyjnych (CABG). Istnieją pewne czynniki zwiększające ryzyko zamknięcia, do których należą przekrój naczynia chorego, wiek oraz hiperlipidemia. Z kolei otyłość jest dobrze udokumentowanym czynnikiem ryzyka choroby wieńcowej. Dotychczas związek pomiędzy otyłością a drożnością pomostów tętniczych, szczególnie z wykorzystaniem tętnicy piersiowej wewnętrznej (LIMA), nie był badany. Cel: Ocena związku pomiędzy otyłością a drożnością pomostów tętniczych w obserwacji długoterminowej. Metody: Poddano analizie angiogramy wszystkich chorych z LIMA. Biorąc pod uwagę drożność LIMA, utworzono dwie grupy chorych: grupa 1 – chorzy z zamkniętym pomostem (n = 59), oraz grupa 2 – chorzy z drożną LIMA (n = 68). Porównano dane demograficzne, hemodynamiczne i laboratoryjne obu grup. Otyłość zdefiniowano jako indeks masy ciała (BMI) ł 30 kg/m2. Wyniki: Średnia wartość BMI w grupie 1 była istotnie wyższa niż w grupie 2 (30,4 ± 3,1 vs 28,7 ± 4,7, p = 0,025). Obie grupy różniły się również pod względem czasu, który upłynął od zabiegu chirurgicznego, stosowanych leków i stężenia HDL-cholesterolu. Dodatkowo chorych podzielono na otyłych i nieotyłych. Otyłość wiązała się ze zwiększonym ryzykiem zamknięcia LIMA: stwierdzono ją u 71% chorych z grupy 1 wobec 25% z grupy 2 (p < 0,001). Analiza wieloczynnikowa wykazała, że ryzyko zamknięcia LIMA było 7,41 razy wyższe u chorych otyłych (95% CI 3,38–16,28). Wnioski: Otyłość jest istotnym i niezależnym czynnikiem ryzyka zamknięcia pomostu tętniczego w obserwacji odległej
Acquired cardiac hypertrophy with outflow tract obstruction in a patient with severe Takayasu arteritis
No full textTakayasu arteritis with coronary artery involvement is rare and its association with secondary cardiac hypertrophy with severe outflow tract obstruction is not common. We describe a case of Takayasu arteritis, diagnosed 10 years ago, whose coronary artery involvement and obstructive cardiac hypertrophy are ascertained after our investigations
Association between metabolic syndrome and late saphenous vein graft disease
No full textObjectives: Saphenous vein grafts have been widely used in coronary bypass operations for many years. We investigated the association between metabolic syndrome (MS) and late saphenous graft disease. Study design: The study included 193 patients (16 females, 177 males; mean age 62 +/- 8 years; range 39 to 86 years) in whom at least one saphenous vein graft had been used during coronary bypass operation of at least 10-year history. All the patients underwent coronary angiography for anginal complaints or preoperative assessment. Patients were classified into two groups. Group 1 was comprised of 72 patients with patent saphenous graft, whereas group 2 included 121 patients without patency or with associated lesions. The two groups were compared in terms of their medications, anthropometric measurements, blood biochemistry, and the presence of hypertension, diabetes mellitus, smoking, and MS. Results: Metabolic syndrome was less frequent in group 1 than in group 2 (22% vs. 45.6%, p=0.003). Metabolic syndrome score, derived from the sum of MS components, was higher in group 2 than in group 1 (2.3 +/- 1 vs. 1.8 +/- 1.2, p=0.003). In a multivariate logistic regression analysis, duration from bypass to coronary angiography (beta=0.812, p=0.017) and MS score (beta=0.590, p=0.005) were found to be independent factors related to saphenous graft patency. Conclusion: Metabolic syndrome score seems to be associated with late saphenous vein graft disease. Early measures for MS may affect the prognosis of patients undergoing coronary bypass operations
