Finding largest rectangles in convex polygons

Cabello, S.,Cheong, O.,Knauer, C.,Schlipf, L. Elsevier 2016 Computational Geometry Vol.51 No.-

<P>We consider the following geometric optimization problem: find a maximum-area rectangle and a maximum-perimeter rectangle contained in a given convex polygon with n vertices. We give exact algorithms that solve these problems in time O(n(3)). We also give (1 - epsilon)-approximation algorithms that take time O(epsilon(-1/2) log n + epsilon(-3/2)). (C) 2015 Elsevier B.V. All rights reserved.</P>

Bayesian data analysis for fusion diagnostics

Jung-Sik Yoon,Rainer Fischer,Jens Knauer,Silvio Gori 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3

The electron density and the electron temperature proles are reconstructed from ruby-laserbased Thomson scattering data on Wendelstein 7-AS (W7-AS) by using Bayesian probability theory (bpt). An outlier identication method based on Bayesian statistics is applied to least-squares minimization ts in order to remove unwanted in uences on th electron density and the electron temperature proles. All uncertainties of the measured data, the calibration measurements, the physical model parameters, and the measurement nuisance parameters are considered in the systematic error analysis. We compare our results with the results from a conventional analysis to determine the electron temperature and density proles from Thomson scattering data on W7-AS.

Covering and piercing disks with two centers

Ahn, H.K.,Kim, S.S.,Knauer, C.,Schlipf, L.,Shin, C.S.,Vigneron, A. Elsevier 2013 Computational geometry Vol.46 No.3

We give exact and approximation algorithms for two-center problems when the input is a set D of disks in the plane. We first study the problem of finding two smallest congruent disks such that each disk in D intersects one of these two disks. Then we study the problem of covering the set D by two smallest congruent disks.

Realistic roofs over a rectilinear polygon

Ahn, H.K.,Bae, S.W.,Knauer, C.,Lee, M.,Shin, C.S.,Vigneron, A. Elsevier 2013 Computational geometry Vol.46 No.9

Given a simple rectilinear polygon P in the xy-plane, a roof over P is a terrain over P whose faces are supported by planes through edges of P that make a dihedral angle π/4 with the xy-plane. According to this definition, some roofs may have faces isolated from the boundary of P or even local minima, which are undesirable for several practical reasons. In this paper, we introduce realistic roofs by imposing a few additional constraints. We investigate the geometric and combinatorial properties of realistic roofs and show that the straight skeleton induces a realistic roof with maximum height and volume. We also show that the maximum possible number of distinct realistic roofs over P is ((n-4)/2@?(n-4)/4@?) when P has n vertices. We present an algorithm that enumerates a combinatorial representation of each such roof in O(1) time per roof without repetition, after O(n<SUP>4</SUP>) preprocessing time. We also present an O(n<SUP>5</SUP>)-time algorithm for computing a realistic roof with minimum height or volume.

Covering a simple polygon by monotone directions

Ahn, H.K.,Brass, P.,Knauer, C.,Na, H.S.,Shin, C.S. Elsevier 2010 Computational Geometry Vol.43 No.5

In this paper we study the problem of finding a set of k directions for a given simple polygon P, such that for each point p@?P there is at least one direction in which the line through p intersects the polygon only once. For k=1, this is the classical problem of finding directions in which the polygon is monotone, and all such directions can be found in linear time for a simple n-gon. For k>1, this problem becomes much harder; we give an O(n<SUP>5</SUP>log<SUP>2</SUP>n)-time algorithm for k=2, and O(n<SUP>3k+1</SUP>logn)-time algorithm for fixed k>=3.

TNF-α-Inhibition Improves the Biocompatibility of Porous Polyethylene Implants In Vivo

Hussain Timon,Gellrich Donata,Siemer Svenja,Reichel Christoph A.,Eckrich Jonas,Dietrich Dimo,Knauer Shirley K.,Stauber Roland H.,Strieth Sebastian 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.2

Background: To improve the biocompatibility of porous polyethylene (PPE) implants and expand their application range for reconstructive surgery in poorly vascularized environments, implants were coated with tumor necrosis factor α (TNFα) inhibitor Etanercept. While approved for systemic application, local application of the drug is a novel experimental approach. Microvascular and mechanical integration as well as parameters of inflammation were analyzed in vivo. Methods: PPE implants were coated with Etanercept and extracellular matrix (ECM) components prior to implantation into dorsal skinfold chambers of C57BL/6 mice. Fluorescence microscopy analyses of angiogenesis and local inflammatory response were thrice performed in vivo over a period of 14 days to assess tissue integration and biocompatibility. Uncoated implants and ECM-coated implants served as controls. Results: TNFα inhibition with Etanercept led to a reduced local inflammatory response: leukocyte-endothelial cell adherence was significantly lowered compared to both control groups (n = 6/group) on days 3 and 14, where the lowest values were reached: 3573.88 leukocytes/mm-2 ± 880.16 (uncoated implants) vs. 3939.09 mm-2 ± 623.34 (Matrigel only) vs. 637.98 mm-2 + 176.85 (Matrigel and Etanercept). Implant-coating with Matrigel alone and Matrigel and Etanercept led to significantly higher vessel densities 7 and 14 days vs. 3 days after implantation and compared to uncoated implants. Mechanical implant integration as measured by dynamic breaking strength did not differ after 14 days. Conclusion: Our data show a reduced local inflammatory response to PPE implants after immunomodulatory coating with Etanercept in vivo, suggesting improved biocompatibility. Application of this tissue engineering approach is therefore warranted in models of a compromised host environment. Background: To improve the biocompatibility of porous polyethylene (PPE) implants and expand their application range for reconstructive surgery in poorly vascularized environments, implants were coated with tumor necrosis factor α (TNFα) inhibitor Etanercept. While approved for systemic application, local application of the drug is a novel experimental approach. Microvascular and mechanical integration as well as parameters of inflammation were analyzed in vivo. Methods: PPE implants were coated with Etanercept and extracellular matrix (ECM) components prior to implantation into dorsal skinfold chambers of C57BL/6 mice. Fluorescence microscopy analyses of angiogenesis and local inflammatory response were thrice performed in vivo over a period of 14 days to assess tissue integration and biocompatibility. Uncoated implants and ECM-coated implants served as controls. Results: TNFα inhibition with Etanercept led to a reduced local inflammatory response: leukocyte-endothelial cell adherence was significantly lowered compared to both control groups (n = 6/group) on days 3 and 14, where the lowest values were reached: 3573.88 leukocytes/mm-2 ± 880.16 (uncoated implants) vs. 3939.09 mm-2 ± 623.34 (Matrigel only) vs. 637.98 mm-2 + 176.85 (Matrigel and Etanercept). Implant-coating with Matrigel alone and Matrigel and Etanercept led to significantly higher vessel densities 7 and 14 days vs. 3 days after implantation and compared to uncoated implants. Mechanical implant integration as measured by dynamic breaking strength did not differ after 14 days. Conclusion: Our data show a reduced local inflammatory response to PPE implants after immunomodulatory coating with Etanercept in vivo, suggesting improved biocompatibility. Application of this tissue engineering approach is therefore warranted in models of a compromised host environment.

Systematic Reliability Study of Top-Gate p- and n-Channel Organic Field-Effect Transistors

Hwang, Do Kyung,Fuentes-Hernandez, Canek,Fenoll, Mathieu,Yun, Minseong,Park, Jihoon,Shim, Jae Won,Knauer, Keith A.,Dindar, Amir,Kim, Hyungchul,Kim, Yongjin,Kim, Jungbae,Cheun, Hyeunseok,Payne, Marcia American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.5

<P>We report on a systematic investigation on the performance and stability of p-channel and n-channel top-gate OFETs, with a CYTOP/Al<SUB>2</SUB>O<SUB>3</SUB> bilayer gate dielectric, exposed to controlled dry oxygen and humid atmospheres. Despite the severe conditions of environmental exposure, p-channel and n-channel top-gate OFETs show only minor changes of their performance parameters without undergoing irreversible damage. When correlated with the conditions of environmental exposure, these changes provide new insight into the possible physical mechanisms in the presence of oxygen and water. Photoexcited charge collection spectroscopy experiments provided further evidence of oxygen and water effects on OFETs. Top-gate OFETs also display outstanding durability, even when exposed to oxygen plasma and subsequent immersion in water or operated under aqueous media. These remarkable properties arise as a consequence of the use of relatively air stable organic semiconductors and proper engineering of the OFET structure.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-5/am405424k/production/images/medium/am-2013-05424k_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am405424k'>ACS Electronic Supporting Info</A></P>