11,743 research outputs found
A Backtracking-Based Algorithm for Computing Hypertree-Decompositions
Hypertree decompositions of hypergraphs are a generalization of tree
decompositions of graphs. The corresponding hypertree-width is a measure for
the cyclicity and therefore tractability of the encoded computation problem.
Many NP-hard decision and computation problems are known to be tractable on
instances whose structure corresponds to hypergraphs of bounded
hypertree-width. Intuitively, the smaller the hypertree-width, the faster the
computation problem can be solved. In this paper, we present the new
backtracking-based algorithm det-k-decomp for computing hypertree
decompositions of small width. Our benchmark evaluations have shown that
det-k-decomp significantly outperforms opt-k-decomp, the only exact hypertree
decomposition algorithm so far. Even compared to the best heuristic algorithm,
we obtained competitive results as long as the hypergraphs are not too large.Comment: 19 pages, 6 figures, 3 table
Dietary patterns of school-age children in Scotland : association with socio-economic indicators, physical activity and obesity
Peer reviewedPublisher PD
SOME EFFECTS OF EDTA AND TETRAPHENYLBORON ON THE ULTRASTRUCTURE OF MITOCHONDRIA IN MOUSE LIVER CELLS
Complexity transitions in global algorithms for sparse linear systems over finite fields
We study the computational complexity of a very basic problem, namely that of
finding solutions to a very large set of random linear equations in a finite
Galois Field modulo q. Using tools from statistical mechanics we are able to
identify phase transitions in the structure of the solution space and to
connect them to changes in performance of a global algorithm, namely Gaussian
elimination. Crossing phase boundaries produces a dramatic increase in memory
and CPU requirements necessary to the algorithms. In turn, this causes the
saturation of the upper bounds for the running time. We illustrate the results
on the specific problem of integer factorization, which is of central interest
for deciphering messages encrypted with the RSA cryptosystem.Comment: 23 pages, 8 figure
Sugar intake and dental decay : results from a national survey of children in Scotland
Peer reviewedPreprin
Ku & C Band solid state switch matrix for satellite payloads using LTCC multilayer substrate
This paper describes the design and development of Ku and C band solid state switch matrix for multimedia satellite payloads. The design, through the use of advanced packaging techniques, allows significant savings on mass and volume with respect to traditional electromechanical switches while guaranteeing a comparable reliability
Visual phosphene perception modulated by subthreshold crossmodal sensory stimulation (vol 27, pg 4178, 2007)
Preterm birth after loop electrosurgical excision procedure (LEEP). how cone features and microbiota could influence the pregnancy outcome
OBJECTIVE:
In the last years, the mean age of women who underwent cervical treatment for high-grade cervical intraepithelial neoplasia (CIN 2-3) is similar to the age of women having their first pregnancy. The aim of this study was to evaluate the risk of preterm birth in subsequent pregnancies after loop electrosurgical excision procedure (LEEP).
PATIENTS AND METHODS:
From January 2013 to January 2016 the study identified a total of 1435 women, nulliparous, who underwent LEEP for CIN 2-3, and who wished to have their first pregnancy. Before surgery, the lengths of the cervix were calculated by transvaginal sonography. After the treatment, the dimension of the removed tissue was evaluated. During the pregnancy, all women carried out periodic transvaginal sonography and vaginal-cervical swabs.
RESULTS:
The average age of patients was 31.96±5.24 years; the interval between the surgical procedure and pregnancy was 12.04±4.67 months; the gestational age at births was 37.53±2.91 weeks. The first vaginal and cervical swab performed during pregnancy was negative in 81.8% of patients. The most prevalent infections were related to C. Albicans, G. Vaginalis, and Group B Streptococcus (GBS). The rate of preterm delivery was significantly higher in women with a minor cervical length.
CONCLUSIONS:
The length and the volume of cervical tissue excised have been shown to be directly related to the risk for preterm birth. Furthermore, vaginal infections and their persistence during pregnancy in women with a history of LEEP may be associated with an increased risk for preterm birth, compared with women with no history of LEEP
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