“无穷”的困扰与“极限”的精确定义

“无限”、“无穷”问题始终在考验和折磨着人类的智力，该问题遍及人类智力范围的所有领域．我们生活在有限的空间里，通过有限的手段和方法对无限开始不懈的追求．这个“魔鬼”无处不在，数学家们历经千年的磨砺，直到19世纪柯西和魏尔斯特拉斯给出极限的精确定义，才完成“降魔”过程，令人惊异的是它竟然有着天使一样美丽的脸庞．     

"无穷"的困扰与"极限"的精确定义

“无限”、“无穷”问题始终在考验和折磨着人类的智力,该问题遍及人类智力范围的所有领域.我们生活在有限的空间里,通过有限的手段和方法对无限开始不懈的追求.这个“魔鬼”无处不在,数学家们历经千年的磨砺,直到19世纪柯西和魏尔斯特拉斯给出极限的精确定义,才完成“降魔”过程,令人惊异的是它竟然有着天使一样美丽的脸庞.     

Prevention of postoperative tendon adhesion by biodegradable electrospun membrane of poly(lactide-co-glycolide)

An electrospun poly(lactide-co-glycolide)(PLGA) membrane was prepared and used to perform the anti-adhesion of Achilles tendon. Throughout the experiments, the membrane showed an appropriate degradation rate, and the p H values of degradation media were maintained at around 7.4. Simultaneously, the excellent biocompatibility of the membrane in vitro and in vivo was confirmed by live/dead and histopathological analyses. Meanwhile, the membrane can reduce tendon adhesion significantly and promote functional recovery effectively. The encouraging results were further demonstrated by hematoxylin and eosin(HE), and Masson's trichrome stainings, and type I collagen immunohistochemical analysis. It was concluded that the model treated with the electrospun PLGA membrane was significantly better with respect to the adhesion prevention and tissue repair than that without treatment. Considering the results of degradation and adhesion prevention efficacy, the electrospun PLGA membrane would be a great candidate for the prevention of postoperative tendon adhesion.     

Updating beliefs about variables given new information on how those variables relate

Bayesian techniques specify how to update beliefs about a variable given information on that variable or related variables. In many cases, statistical analyses also provide information about the relationship between variables, but the Borel Paradox prohibits many natural ways of updating beliefs conditioned on information about a relationship. This paper presents a method by which beliefs can be updated without violating the Borel Paradox under certain circumstances. We apply our approach to relationships specified by a statistical model (i.e., regression), and relationships described by statistical simulation.     

Apportionment methods

Most democratic countries use apportionment methods to transform election results into whole numbers, which usually give the number of seats in a legislative body that the parties obtained. Which apportionment method does this best can be specified by measuring the error between the allocated result and the ideal proportion. We show how to find an apportionment method which is best suited to a given error function. We also discuss several properties of apportionment methods that have been labelled paradoxa. In particular we explain the highly publicised “Alabama” Paradox for the Hare/Hamilton method and show that other popular apportionment methods come with their very own paradoxa.     

Procyanidins are potent inhibitors of LOX-1: a new player in the French Paradox

Lectin-like oxidized LDL receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL (oxLDL) and plays multiple roles in the development of cardiovascular diseases. We screened more than 400 foodstuff extracts for identifying materials that inhibit oxLDL binding to LOX-1. Results showed that 52 extracts inhibited LOX-1 by more than 70% in cell-free assays. Subsequent cell-based assays revealed that a variety of foodstuffs known to be rich in procyanidins such as grape seed extracts and apple polyphenols, potently inhibited oxLDL uptake in Chinese hamster ovary (CHO) cells expressing LOX-1. Indeed, purified procyanidins significantly inhibited oxLDL binding to LOX-1 while other ingredients of apple polyphenols did not. Moreover, chronic administration of oligomeric procyanidins suppressed lipid accumulation in vascular wall in hypertensive rats fed with high fat diet. These results suggest that procyanidins are LOX-1 inhibitors and LOX-1 inhibition might be a possible underlying mechanism of the well-known vascular protective effects of red wine, the French Paradox.     

关于吉布斯佯谬的解释

吉布斯佯谬存在两种说法，在此针对有关文献对这两种说法的阐述进行说明，然后对其解释进行讨论，提出：根据全同性原理的诠释，在统计物理范围内可以解释吉布斯佯谬．     

Extragalactic background light: inventory of light throughout the cosmic history

The Extragalactic Background Light (EBL) stands for the mean surface brightness of the sky as we would see it from a representative vantage point in the intergalactic space outside of our Milky Way Galaxy. Averaged over the whole 4π solid angle it represents the collective light from all luminous matter radiated throughout the cosmic history. Part of the EBL is resolved into galaxies that, with the increasing detecting power of giant telescopes and sensitive detectors, are seen to deeper and deeper limiting magnitudes. This resolved part is now known to contribute a substantial or even the major part of the EBL. There still remains, however, the challenge of finding out to what extent galaxies too faint or too diffuse to be discerned individually, individual stars or emission by gas outside the galaxies, or – more speculatively – some hitherto unknown light sources such as decaying elementary particles are accounting for the remaining EBL. We review the recent progress that has been made in the measurement of EBL. The current photometric results suggest that there is, beyond the resolved galaxies, an EBL component that cannot be explained by diffuse galaxy halos or intergalactic stars.     

Krackow及Kessler缝合法联合抗菌薇乔缝线治疗闭合性跟腱断裂疗效研究

目的选取采用Krackow及Kessler两种缝合法并联合抗菌薇乔缝线治疗闭合性跟腱断裂,比较和评判两种缝合方法的临床疗效.方法选取新鲜闭合性跟腱断裂患者32例,根据手术缝合方法将患者分为两组,即Krackow缝合法组(18例)及Kessler缝合法组(14例),分别进行手术治疗,术后采用相同方法进行功能锻炼,根据Arner-Lindholm标准对随访患者进行临床疗效评定.结果 1)两种缝合法术后并发症发生率比较差异无统计学意义(P0.05).2)Krackow缝合法患者疗效优秀率和总体优良率分别为72.2%和100%,Kessler缝合法分别为57.1%和92.8%,两组疗效优秀率差异具有显著统计学意义(P0.05).3)Krackow缝合法和Kessler缝合法患者总体满意率分别为94.4%和71.4%,二者比较差异具有显著统计学意义(P0.05).结论 Krackow缝合法联合抗菌薇乔缝线对于手术治疗闭合性跟腱断裂疗效更加确切,其术后患者满意度、临床疗效优秀率等方面明显优于Kessler缝合法.