Measuring the strength of knotted suture materials

There is no international standard method for measuring the strength of knotted suture materials, and although several methods have been published, there has been minimal investigation on the effects of test variables on measured properties (e.g. speed, gauge length, and knot tensioning force). Methods investigated in this work were the “ear method” (with and without a rod inside the loop), and the “cut-loop and ear method”. The test environment, material, and type of knot were constant. Effects of varying gauge length, test speed, and knot-tensioning force on tenacity and strain were investigated and compared with data for nonknotted sutures. Different values of tenacity and strain were evident for the different test methods; lower values of tenacity for specimens with shorter gauge lengths and tested at greater speeds; lower values of strain for specimens with longer gauge lengths and tested at greater speeds. Thus, tensile properties of suture materials tested at one gauge length or one test speed, as widely reported in the literature, may be misleading. Knot tensioning force neither affect tenacity nor strain.     

不要让像素迷住双眼

数码相机有比高像素更重要的东西,所以不要上市场宣传的当。     

On the Flattest Common Supersequence Method for Deadlock-Free Routing in Arbitrary Networks

In this paper we consider the problem of deadlock-free routing in arbitrary parallel and distributed computers. We focus on asynchronous routing algorithms which continuously receive new packets to route and which do not discard packets that encounter congestion. Specifically, we examine what we call the deadlock-free routing (DFR ) problem. The input to the DFR problem consists of an arbitrary network and an arbitrary set of paths in the network. The output consists of a routing algorithm, which is a list of the buffers used along each of the paths. The routing algorithm is required to be free from deadlock and the goal is to minimize the number of buffers required in any one node. We study the DFR problem by converting it into an equivalent problem which we call the flattest common supersequence (FCS ) problem. The input to the FCS problem consists of a set of sequences and the output consists of a single sequence that contains all of the input sequences as (possibly noncontiguous) subsequences. The goal of the FCS problem is to minimize the maximum frequency of any symbol in the output sequence. We present three main results. First, we prove that the decision version of the FCS problem is NP-complete, and has no polynomial-time approximation scheme unless P= NP . An alternative proof is presented which shows that unlike the shortest common supersequence (SCS) problem, the FCS problem is still NP-complete for two input sequences. This implies that approximation algorithms for FCS based on an exact pairwise merge are not possible. Next, we propose and experimentally evaluate a range of heuristics for FCS. Our experimental results show that one of these heuristics performs very well over a wide range of inputs. Lastly, we prove that this heuristic is in fact optimal for certain restricted classes of inputs. Online publication November 27, 2000.     

A light-weight cooling vest enhances performance of athletes in the heat

During the 1990s, emphasis on the health and safety of people who exercise in hot, humid conditions increased and many organizations became aware of the need for protection against heat-related disorders. A practical, pre-cooling strategy applicable to several sporting codes, which is low cost, easy to use, light-weight and which enhances cooling of the human body prior to and following exercise, was developed and tested. Eight males and eight females participated in a maximal oxygen consumption (VO2max) test and four trials: a control (without cooling) and wearing each of three different cooling vests (A, B, C). Vests were worn during the rest, stretch, warm-up (50% VO2max) and recovery stages of the protocol, but not during the 30 min run (70% VO2max). Core and skin temperatures during exercise were reduced (by approximately 0.5 degrees C, rectal; 0.1-1.4 degrees C, abdominal skin temperature) and sweat rates were lower (by approximately 10-23%). Endurance times for running at 95% of VO2max were increased by up to 49 s. Perceptions of the thermal state and skin wetness showed changes to greater levels of satisfaction. Physiological and sensory responses were related to design features of the vests.     

Group interaction and perceived simliarity of members.

The hypothesis being tested was that perceived similarity of other members of a group with oneself was a function of the degree of interaction in the group. An experimental situation (making lists of geographical names with or without the assistance of group members) offered the possibility to vary the degree of group interaction. The findings revealed that assumed (perceived) similarity between Ss was a function of degree of group interaction only when Ss did not know each other beforehand. From Psyc Abstracts 36:02:2GE35S. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

一种新的齿轮啮合效率计算方法探讨

在对平面高副机构传动效率的通用计算公式分析的基础上，推导出了一种新的齿轮传动装置的啮合效率的计算公式，并对该公式的正确性做了验证。     

Albumin adsorption to contact lens materials: A review

During contact lens wear, tear film components such as lipids, mucins and proteins tend to deposit on and within the lens material and may cause discomfort, reduced vision and inflammatory reactions. The tear film protein that has attracted most interest when studying contact lens deposition is the small (14 kDa), positively charged protein lysozyme. Albumin, which is a much larger protein (66 kDa) with an overall net negative charge is also of interest, and shows very different adsorption patterns to lysozyme. The concentration of albumin in the tear film is relatively low compared to the concentration in blood serum, but this value increases markedly under various conditions, including when the eye is closed, during contact lens wear and in various dry eye states. Gaining an understanding of the manner in which albumin deposits on biomaterials is of importance for contact lens wear, as well as for other medical applications where HEMA-based materials are used for implants, artificial blood vessels or drug delivery devices. This review paper summarizes the impact of individual material compositions, water content, hydrophobicity and electrostatic attraction on the adsorption behavior of the protein albumin.