String theory,Einstein, and the identity of physics: Theory assessment in absence of the empirical

String theorists are certain that they are practicing physicists. Yet, some of their recent critics deny this. This paper argues that this conflict is really about who holds authority in making rational judgment in theoretical physics. At bottom, the conflict centers on the question: who is a proper physicist? To illustrate and understand the differing opinions about proper practice and identity, we discuss different appreciations of epistemic virtues and explanation among string theorists and their critics, and how these have been sourced in accounts of Einstein's biography. Just as Einstein is claimed by both sides, historiography offers examples of both successful and unsuccessful non-empirical science. History of science also teaches that times of conflict are often times of innovation, in which novel scholarly identities may come into being. At the same time, since the contributions of Thomas Kuhn historians have developed a critical attitude towards formal attempts and methodological recipes for epistemic demarcation and justification of scientific practice. These are now, however, being considered in the debate on non-empirical physics.     

Retrograde transport of endocytosed Shiga toxin to the endoplasmic reticulum.

Shiga toxin and some other protein toxins that act on targets in the cytosol have previously been shown to enter the trans-Golgi network. Transport by this route may be necessary for translocation of the toxin to the cytosol and for intoxication, but it is not known whether the enzymatically active part of the toxins actually enters the cytosol from the trans-Golgi network. It has been suggested that such toxins are transported in a retrograde manner to the endoplasmic reticulum and that translocation occurs in this organelle, but retrograde transport of endocytosed material beyond the trans-Golgi network has never been demonstrated. Here we show that in butyric acid-treated A431 cells endocytosed Shiga toxin is not only transported to the trans-Golgi network, but also to all Golgi stacks, to the endoplasmic reticulum and to the nuclear envelope. Furthermore, butyric acid sensitizes the cells to Shiga toxin, which is consistent with the possibility that retrograde transport is required for translocation of the toxin to the cytosol.     

Chromosomal localization of a unique gene by non-autoradiographic in situ hybridization

During the past few years, several methods have been developed for the detection of specific nucleic acid sequences by in situ hybridization using non-radioactive labels such as fluorochromes, cytochemically detectable enzymes and electron-dense markers. These methods are preferable to autoradiography in terms of speed of performance and topological resolution. Their limited sensitivity, however, has so far restricted their use to the detection of repeated sequences. Here we report single gene detection with a procedure using 2-acetylaminofluorene (AAF)-modified probes, immunoperoxidase cytochemistry and reflection-contrast microscopy. We confirmed the autoradiographic data on the localization of the human thyroglobulin (Tg) gene to the distal end of the long arm of chromosome 8. A mixture of cosmid cHT2-derived subclones of the 3' part of the Tg gene, 22.3 kilobase pairs (kbp) in total, was used as a hybridization probe. This procedure can be used to map other unique sequences, if genomic clones are available from which clones with an appropriate amount of inserts can be isolated.     

In vitro protein synthesis and α amylase activity in F cells from hepatopancreas ofPalaemon serratus (Crustacea; Decapoda)

In crustaceans, all the steps in the assimilation of food take place in the hepatopancreas. To facilitate the study of this organ, a method for the dissociation of cell types was developed. The hepatopancreas of the prawnPalaemon serratus was mechanically dissociated and the cells separated by Percoll density-gradient centrifugation. The E and R cells had similar densities of around 1.05 g/ml. The F cells were separated into two distinct fractions with densities of 1.075 and 1.082 g/ml. The B cells sedimented at a density of 1.12 g/ml. The ratio between the two populations of F cells was found to vary during the intermolt cycle while B cells disappeared after the molt. When the density gradient fractions were incubated with³H-leucine, incorporation was highest in the F cell fractions. Measurements of -amylase activity, indicated that the two populations of F cells may be derived from the same cell type.     

Regulation of cellulose synthesis in Acetobacter xylinum by cyclic diguanylic acid

Cellulose is the most abundant renewable carbon resource on earth and is an indispensable raw material for the wood, paper, and textile industries. A model system to study the mechanism of cellulose biogenesis is the bacterium Acetobacter xylinum which produces pure cellulose as an extracellular product. It was from this organism that in vitro preparations which possessed high levels of cellulose synthase activity were first obtained in both membranous and soluble forms. We recently demonstrated that this activity is subject to a complex multi-component regulatory system, in which the synthase is directly affected by an unusual cyclic nucleotide activator enzymatically formed from GTP, and indirectly by a Ca (2+) -sensitive phosphodiesterase which degrades the activator. The cellulose synthase activator (CSA) has now been identified as bis-(3' 5')-cyclic diguanylic acid (5'G3'p5'G3'p) on the basis of mass spectroscopic data, nuclear magnetic resonance analysis and comparison with chemically synthesized material. We also report here on intermediary steps in the synthesis and degradation of this novel circular dinucleotide, which have been integrated into a model for the regulation of cellulose synthesis.     

近炸引信炮口保险距离的计算

该文以国外某舰炮弹药无线电近炸引信为例,分析研究了该无线电近炸引信炮口安全保险距离有关的参量,通过对火药燃烧时间和电路延迟时间的计算推出了几种不同情况下该无线电近炸引信炮口保险距离,分析计算方法具有普遍性。     

利用二苯并—18—冠—6从硫氰酸盐溶液中萃取铜（Ⅱ）的研究

报道了在二苯并－１８－冠－６（ＤＢＣ）的１,２－二氯乙烷溶液中,从硫氰酸盐溶液萃取铜时,冠醚浓度,硫氰酸盐浓度和氢离子浓度对萃取的影响,结果表明,当硫氰酸钾浓度大大超过铜浓度和氢离子浓度（０．１ｍｏｌ／Ｌ）时,ＤＢＣ可有效地萃取铜,作者从实验结果推断其萃合物的组成为Ｃｕ（ＳＣＮ）＾－３Ｋ＾＋（ＤＢＣ）２（ｏ）。     

Transplantation of human cortex with Alzheimer's disease into rat occipital cortex; a model for the study of Alzheimer disease

Summary Senile dementia of the Alzheimer type (SDAT) is a major problem in the human senescent population. As this pathology cannot be reproduced in animals, research into its development is greatly impeded. The technique of implantation of the nervous tissue has been utilized in order to establish an animal model and to test the possible existence of a transmissible agent. When human temporal cortex with Alzheimer's disease is implanted in the occipital cortex of 7-week-old rats, human cerebral tissue containing abundant tangles induces in the receiver cortex a reactive fibrous gliosis. In the processes of the astrocytes, twisted filaments are evident among bundles of normal filaments. These alterations could be induced by the metabolising of abnormal filament subunits or by some infectious agent introduced by the implant.This study is supported by grant No. 2.4517.82 of Fonds de la Recherche Fondamentale Collective of Belgium.     

浅谈增钙粉煤灰在抹灰工程中的应用

本文结合工程实际,讨论了用粉煤灰作抹灰砂浆的掺合料在建筑工程中的应用情况,分析了它的应用条件、优点、使田中应予注意的一系列有关问题及其发展前景。     

椭圆变分不等式的小扰动

研究Ｂａｎａｃｈ空间中椭圆变分不等式的扰动问题，得到了扰动问题存在唯一解的一个充分条件；并用它处理了一类半线性微分积分方程的边值问题．设Ｖ是可分自反Ｂａｎａｃｈ空间，Ｖ′是Ｖ的对偶空间，Ｋ是Ｖ中非空闭凸子集，则有定理１设Ｔ：Ｖ→Ｖ′，Ａ：Ｋ→Ｖ′，且满足（ｉ）Ｔ是有界线性算子，存在常数α＞０，使得（Ｔｖ，ｖ）≥αｖ２，ｖ∈Ｖ；（ｉ）Ａ是伪单调算子，存在常数λ＞０，使得（Ａｕ－Ａｖ，ｕ－ｖ）≤λｕ－ｖ２，ｕ，ｖ∈Ｋ；（ｉｉ）α＞λ．则存在唯一的ｕ∈Ｋ，使得（Ｔｕ，ｖ－ｕ）＋（Ａｕ，ｖ－ｕ）≥（ｆ，ｖ－ｕ），ｕ∈Ｋ