Covering Points by Disjoint Boxes with Outliers

For a set of n points in the plane, we consider the axis--aligned (p,k)-Box Covering problem: Find p axis-aligned, pairwise-disjoint boxes that together contain n-k points. In this paper, we consider the boxes to be either squares or rectangles, and we want to minimize the area of the largest box. For general p we show that the problem is NP-hard for both squares and rectangles. For a small, fixed number p, we give algorithms that find the solution in the following running times: For squares we have O(n+k log k) time for p=1, and O(n log n+k^p log^p k time for p = 2,3. For rectangles we get O(n + k^3) for p = 1 and O(n log n+k^{2+p} log^{p-1} k) time for p = 2,3. In all cases, our algorithms use O(n) space.Comment: updated version: - changed problem from 'cover exactly n-k points' to 'cover at least n-k points' to avoid having non-feasible solutions. Results are unchanged. - added Proof to Lemma 11, clarified some sections - corrected typos and small errors - updated affiliations of two author

Inscribing or Circumscribing a Histogon to a Convex Polygon

We consider two optimization problems of approximating a convex polygon, one by a largest inscribed histogon and the other by a smallest circumscribed histogon. An axis-aligned histogon is an axis-aligned rectilinear polygon such that every horizontal edge has an integer length. A histogon of orientation ? is a copy of an axis-aligned histogon rotated by ? in counterclockwise direction. The goal is to find a largest inscribed histogon and a smallest circumscribed histogon over all orientations in [0,?). Depending on whether the horizontal width of a histogon is predetermined or not, we consider several different versions of the problem and present exact algorithms. These optimization problems belong to shape analysis, classification, and simplification, and they have applications in various cost-optimization problems

PwRn1, a novel Ty3/gypsy-like retrotransposon of Paragonimus westermani: molecular characters and its differentially preserved mobile potential according to host chromosomal polyploidy

<p>Abstract</p> <p>Background</p> <p>Retrotransposons have been known to involve in the remodeling and evolution of host genome. These reverse transcribing elements, which show a complex evolutionary pathway with diverse intermediate forms, have been comprehensively analyzed from a wide range of host genomes, while the information remains limited to only a few species in the phylum Platyhelminthes.</p> <p>Results</p> <p>A LTR retrotransposon and its homologs with a strong phylogenetic affinity toward <it>CsRn1 </it>of <it>Clonorchis sinensis </it>were isolated from a trematode parasite <it>Paragonimus westermani </it>via a degenerate PCR method and from an insect species <it>Anopheles gambiae </it>by <it>in silico </it>analysis of the whole mosquito genome, respectively. These elements, designated <it>PwRn1 </it>and <it>AgCR-1 </it>– <it>AgCR-14 </it>conserved unique features including a t-RNA^Trpprimer binding site and the unusual CHCC signature of Gag proteins. Their flanking LTRs displayed >97% nucleotide identities and thus, these elements were likely to have expanded recently in the trematode and insect genomes. They evolved heterogeneous expression strategies: a single fused ORF, two separate ORFs with an identical reading frame and two ORFs overlapped by -1 frameshifting. Phylogenetic analyses suggested that the elements with the separate ORFs had evolved from an ancestral form(s) with the overlapped ORFs. The mobile potential of <it>PwRn1 </it>was likely to be maintained differentially in association with the karyotype of host genomes, as was examined by the presence/absence of intergenomic polymorphism and mRNA transcripts.</p> <p>Conclusion</p> <p>Our results on the structural diversity of <it>CsRn1</it>-like elements can provide a molecular tool to dissect a more detailed evolutionary episode of LTR retrotransposons. The <it>PwRn1</it>-associated genomic polymorphism, which is substantial in diploids, will also be informative in addressing genomic diversification following inter-/intra-specific hybridization in <it>P. westermani </it>populations.</p

Graphene for Controlled and Accelerated Osteogenic Differentiation of Human Mesenchymal Stem Cells

Modern tissue engineering strategies combine living cells and scaffold materials to develop biological substitutes that can restore tissue functions. Both natural and synthetic materials have been fabricated for transplantation of stem cells and their specific differentiation into muscles, bones and cartilages. One of the key objectives for bone regeneration therapy to be successful is to direct stem cells' proliferation and to accelerate their differentiation in a controlled manner through the use of growth factors and osteogenic inducers. Here we show that graphene provides a promising biocompatible scaffold that does not hamper the proliferation of human mesenchymal stem cells (hMSCs) and accelerates their specific differentiation into bone cells. The differentiation rate is comparable to the one achieved with common growth factors, demonstrating graphene's potential for stem cell research.Comment: 34 pages, 11 figures, 1 table, submitte

Cigarette Smoking and Risk of Lung Cancer in Korean Men: The Seoul Male Cancer Cohort Study

Lung cancer is the leading cause of cancer deaths in Korea. The aim of this study was to estimate lung cancer risk of cigarette smoking in Korean men by a 10-yr follow-up prospective cohort study using the primary databases. The number of subjects was 14,272 men, who had full information of smoking habits among participants in the Seoul Male Cancer Cohort Study (SMCC). Total 125,053 person-years were calculated by determining the number of days from the start of follow-up, January 1, 1993, until the date of lung cancer diagnosis, death from another cause, or the end of follow-up, December 31, 2002, followed by converting the number of days to years. The information of outcome was obtained by the database of Korea Central Cancer Registry, Seoul Regional Cancer Registry, and Korea Statistical Office. The relative risk (RR) and its 95% confidence interval (CI) values of smoking were calculated using Cox proportional hazards regression stratified on potential confounders. During the follow-up periods, 78 cases of lung cancer occurred. The cigarette smoking is the major risk factor and increases the 4.18-fold risk of lung cancer in Korean men. In order to control lung cancer, intervention of quitting smoking is needed

Safety and optimal neuroprotection of neu2000 in acute ischemic stroke with reCanalization: study protocol for a randomized, double-blinded, placebo-controlled, phase-II trial

BACKGROUND: The potential of neuroprotective agents should be revisited in the era of endovascular thrombectomy (EVT) for acute large-artery occlusion because their preclinical effects have been optimized for ischemia and reperfusion injury. Neu2000, a derivative of sulfasalazine, is a multi-target neuroprotectant. It selectively blocks N-methyl-D-aspartate receptors and scavenges for free radicals. This trial aimed to determine whether neuroprotectant administration before EVT is safe and leads to a more favorable outcome. METHODS: This trial is a phase-II, multicenter, three-arm, randomized, double-blinded, placebo-controlled, blinded-endpoint drug trial that enrolled participants aged ≥ 19 years undergoing an EVT attempt less than 8 h from symptom onset, with baseline National Institutes of Health Stroke Scale (NIHSS) score ≥ 8, Alberta Stroke Program Early CT score ≥ 6, evidence of large-artery occlusion, and at least moderate collaterals on computed tomography angiography. EVT-attempted patients are randomized into control, low-dose (2.75 g), and high-dose (5.25 g) Neu2000KWL over 5 days. Seventy participants per group are enrolled for 90% power, assuming that the treatment group has a 28.4% higher proportion of participants with functional independence than the placebo group. The primary outcome, based on intention-to-treat criteria is the improvement of modified Rankin Scale (mRS) scores at 3 months using a dichotomized model. Safety outcomes include symptomatic intracranial hemorrhage within 5 days. Secondary outcomes are distributional change of mRS, mean differences in NIHSS score, proportion of NIHSS score 0-2, and Barthel Index > 90 at 1 and 4 weeks, and 3 months. DISCUSSION: The trial results may provide information on new therapeutic options as multi-target neuroprotection might mitigate reperfusion injury in patients with acute ischemic stroke before EVT