Search in Publications

Found 6515 publications

A numerical C1-shadowing result for retarded functional differential equations

Gyula Farkas

Publication Name: Journal of Computational and Applied Mathematics

Publication Date: 2002-08-15

Volume: 145

Issue: 2

Page Range: 269-289

Description:

The aim of the present paper is to give a numerical C1-shadowing between the exact solutions of a functional differential equation and its numerical approximations. The shadowing result is obtained by comparing exact solutions with numerical approximation which do not share the same initial value. Behavior of stable manifolds of functional differential equations under numerics will follow from the shadowing result. © 2001 Elsevier Science B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/S0377-0427(01)00581-7

Construction of two-sided bounds for initial-boundary value problems

C. Grossmann Zoltán Horváth

Publication Name: Applied Numerical Mathematics

Publication Date: 2002-08-01

Volume: 42

Issue: 1-3

Page Range: 177-187

Description:

The present paper extends the bounding operator approach developed for boundary value problems to the case of initial-boundary value problems (IBVPs). Following the general principle of bounding operators enclosing methods for the case of partial differential equations are discussed. In particular, continuous discretization methods with an appropriate error bound controlled shift and monotone extensions of Rothe's method for parabolic problems are investigated. © 2001 IMACS. Published by Elsevier Science B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/S0168-9274(01)00149-0

An update on recurrent acute pancreatitis: Data from five European countries

Gyula Farkas Hans Beger Paul Lankisch Philippe Levy Raffaele Pezzilli Lucio Gullo Constantine Arvanitakis Marina Migliori Attila Oláh

Publication Name: American Journal of Gastroenterology

Publication Date: 2002-08-01

Volume: 97

Issue: 8

Page Range: 1959-1962

Description:

OBJECTIVE: A great number of studies have been published on acute pancreatitis, but few have focused on the recurrent form. In this study, we have sought to determine the relative frequency and mortality of recurrent acute pancreatitis, and also to update our knowledge of its etiological factors. METHODS: Patients were selected from a total of 1068 persons included in a previous European study of acute pancreatitis. All were admitted to a hospital with an attack of acute pancreatitis between January, 1990 and December, 1994. Data for each patient was recorded on a standardized form. RESULTS: Of the 1068 with acute pancreatitis, 288 (27%) had recurrent pancreatitis; the majority (78.8%) were men, with a mean age of 43 yr (range 16-95 yr). Regarding etiology, alcohol was the most frequent factor (57%), followed by gallstones (25%), other factors (7.6%), and no identified factor (10.4%). Of the 288 patients, 17 (5.9%) died, all of whom had necrotizing pancreatitis; among all of the patients with necrotizing pancreatitis (141 of 288), the mortality was 12.1%. These percentages are lower than those for patients who had a single attack (8.5% and 18.6%, respectively), but not to a statistically significant degree. Mortality was significantly lower among patients with alcoholic pancreatitis (6.9%) than among those with biliary (30%) (p < 0.002) or idiopathic pancreatitis (25%) (p < 0.04). Most of the deaths (82.4%) occurred at the second attack of pancreatitis. CONCLUSION: Acute recurrent pancreatitis remains a frequent disease, with alcohol being the most frequent etiological factor. Mortality is similar to that of a single episode of acute pancreatitis, and it is significantly lower among patients with alcohol as the etiology. © 2002 by Am. Coll. of Gastroenterology.

Open Access: Yes

DOI: 10.1016/S0002-9270(02)04264-8

Nonexistence of uniform exponential dichotomies for delay equations

Gyula Farkas

Publication Name: Journal of Differential Equations

Publication Date: 2002-06-10

Volume: 182

Issue: 1

Page Range: 266-268

Description:

No description provided

Open Access: Yes

DOI: 10.1006/jdeq.2001.4156

An open architecture patient monitoring system using standard technologies

Balázs Benyó Z. Benyó Péter Várady

Publication Name: IEEE Transactions on Information Technology in Biomedicine

Publication Date: 2002-03-01

Volume: 6

Issue: 1

Page Range: 95-98

Description:

Computer-aided bedside patient monitoring is applied in areas where real-time vital function analysis takes place. Modern bedside monitoring requires not only the networking of bedside monitors with a central monitor but also other standard communication interfaces. In this paper, a novel approach to patient monitoring is introduced. A patient monitoring system was developed and implemented based on an existing industry standard communication network, using standard hardware components and software technologies. The open architecture system design offers scalability, standard interfaces, and flexible signal interpretation possibilities.

Open Access: Yes

DOI: 10.1109/4233.992168

Effect of subsoiling on the yield of sugar beet under conditions of rhizomania infection.

G. Kuroli Lajos Németh

Publication Name: Mededelingen Rijksuniversiteit Te Gent Fakulteit Van De Landbouwkundige En Toegepaste Biologische Wetenschappen

Publication Date: 2002-01-01

Volume: 67

Issue: 2

Page Range: 321-325

Description:

The rhizomania is known in Hungary since 1982. The causal agent, Beet necrotic yellow vein benyvirus (BNYVV) is transmitted by a soil-borne fungus Polymyxa betae Keskin. A field experiment was done under rhizomania infested and non-infested conditions to compare the yield parameters of five tolerant and four sensitive sugar beet hybrids. Tolerant varieties produced higher root yield under rhizomania infected conditions. The root yields of the sensitive varieties were similar to the tolerant ones on the uninfested field, but the root mass of some tolerant varieties exceeded the production of the former group. Subsoiling was carried out in two strips of a heavily infested field, while conventional soil cultivation was done on the other parts. There was not any other difference in the cultivation of the treated and control areas. Sugar beet root samples were collected at the time of harvesting from the subsoiled and control plots. Beet necrotic yellow vein virus (BNYVV) infection was tested by means of ELISA. Virus content, yield and yield parameters of samples were compared. There were no significant differences in virus infection between sugar beet roots derived from subsoiled and untreated plots. Ratio of BNYVV infected plants was about 90% in both areas. However, yield and yield parameters showed remarkable difference. Root yield of treated plots, calculated from average individual root weight and 80,000 plant/ha plant density exceeded by 140% the yield of control. Sugar content was 2.6% higher and the harmful non-sugar content was lower on the subsoiled plots. Owing to the favourable chemical and technological value of beet the white sugar content was approximately three-times higher on the treated area.

Open Access: Yes

DOI: DOI not available

An accelerated digital CNN-UM (CASTLE) architecture by using the pipe-line technique

P. Keresztes Timót Hidvégi Péter Szolgay

Publication Name: Proceedings of the IEEE International Workshop on Cellular Neural Networks and their Applications

Publication Date: 2002-01-01

Volume: 2002-January

Issue: Unknown

Page Range: 355-362

Description:

Different CNN-UM architecture implementations, analog and emulated digital, were developed. The emulated digital architecture (CASTLE) is accurate but slower than the analog CNN-UMs. It is generally disadvantageous especially if transient computing is critical. The operation speed of the emulated digital implementations, namely CASTLE, can be increased significantly using the pipeline technique. This solution is analyzed with respect to area, time, etc. These arithmetic cores were tested and simulated using a VIRTEX FPGA development system.

Open Access: Yes

DOI: 10.1109/CNNA.2002.1035070

Public-Private Partnership (PPP) as a social game

P. Scharle

Publication Name: Innovation

Publication Date: 2002-01-01

Volume: 15

Issue: 3

Page Range: 227-252

Description:

Discrepancy between social demands and public resources has become apparent in many countries worldwide. Institutions and industries involved in public services seek new forms of collaboration and combine all available public and private skills to circumvent problems. Advocates of public-private partnership (PPP) assess the progress as convincing. Reserved observers argue that the technique has immanent weaknesses. Putting the phenomena, experience, and discussion into a wider context of gaming helps to arrive at a better comprehension. The paper focuses on road transportation infrastructure issues but its conclusions are of broader interest. Four perspectives are chosen to discuss PPP as a gaming issue. Linguistics, the mathematical theory of games, experimental psychology and the theory of institutions offer useful analytical concepts, theorems and approaches. The gaming perspective allows us to identify and define more clearly several uncertain or misinterpreted situations or actions experienced in PPP implementations. The conceptual identification of positions, motivations and further characteristics is not only possible but helps all partners to better understand the structure, the rules and roles given in the procedure. Use of the gaming perspective in PPP issues seems to enhance 'fair play'. Expected trends of development and further areas of suggested research are derived from the conclusions and conjectures. Application of the gaming perspective is recommended in the development of project delivery techniques, education and training.

Open Access: Yes

DOI: 10.1080/1351161022000027630

Conjugacy in the discretized fold bifurcation

Gyula Farkas

Publication Name: Computers and Mathematics with Applications

Publication Date: 2002-01-01

Volume: 43

Issue: 8-9

Page Range: 1027-1033

Description:

In this paper, we construct a conjugacy between the time-1-map of the solution flow generated by an ordinary differential equation and its numerical approximation in a neighborhood of a fold bifurcation point. Our main result is that the conjugacy is O(hp)-close to the identity on the center manifold where h is the step size and p is the order of the numerical method. © 2002 Elsevier Science Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/S0898-1221(02)80011-6