Scale Factor Determination of Micro-Machined Angular Rate Sensors Without a Turntable

Introduction Micro-machined angular rate sensors or gyroscopes are used to measure the angular velocity of a moving ob- ject without an external reference. Low cost, high pre- cision gyroscopes find a large market in consumer products, automobiles, medica…     

Measures of effectiveness in medical research: Reporting both absolute and relative measures

Biomedical research, especially pharmaceutical research, has been criticised for engaging in practices that lead to over-estimations of the effectiveness of medical treatments. A central issue concerns the reporting of absolute and relative measures of medical effectiveness. In this paper we critically examine proposals made by Jacob Stegenga to (a) give priority to the reporting of absolute measures over relative measures, and (b) downgrade the measures of effectiveness (effect sizes) of the treatments tested in clinical trials (Stegenga, 2015a). After exposing significant flaws in a central case study used by Stegenga to bolster his first proposal (a), we go on to argue that neither of these proposals is defensible (a or b). We defend the practice, in line with the New England Journal of Medicine, of reporting both absolute and relative measures whenever feasible.     

From positivism to conventionalism: Comte,Renouvier, and Poincaré

Considered in its historical context, conventionalism is quite different from the way in which it has been caricatured in more recent philosophy of science, that is, as a conservative philosophy that allows the preservation of theories through arbitrary ad hoc stratagems. It is instead a liberal outgrowth of Comtean positivism, which broke with the Reidian interpretation of the Newtonian tradition in France and defended a role for hypotheses in the sciences. It also has roots in the social contract political philosophy of Renouvier, who explicitly drew the analogy between conventions in political life and the conventional acceptance of hypotheses in the sciences, and conceived a philosophy that permits scientists to set aside foundational worries and explore new ideas. Although Poincaré and Renouvier may have hesitated to accept certain then recent developments in mathematics and the sciences such as non-Euclidean geometries, this conservatism cannot necessarily be attributed to their conventionalism. It may instead reflect the engineering background they shared with Comte, which emphasizes practical applications. Although Renouvier and Poincaré may have seen no practical use for these new ideas, unlike Comte they did not prohibit others from pursuing them, reflecting conventionalism's more liberal attitude toward recent developments in the sciences.     

John Wheeler’s Desert Island: The conservatism of non-empirical physics

This paper argues that non-empirical physics, as paradigmatically embodied by string theory, is a conservative research program, in spite of appearances. John Wheeler's 1950s research program of "daring conservatism" is identified as another non-empirical research program that checks all the same boxes as string theory. This case study is used to further analyze the connection between conservatism and a non-empirical approach. It is concluded that the prime difficulty of non-empirical physics is not that it involves unbridled speculation, but that the lack of empirical input prevents it from achieving revolutionary progress.     

拉伐尔喷嘴中气粉流的计算及喷嘴扩张段设计

根据作者关于拉伐尔喷嘴中气粉流行为的数学模型,采用确定喷嘴临界截面的压强检验法,对不同的粉气比 λ=0.1 ～0.9和不同的粉粒直径d_p=1～50 μm,讨论了对喷嘴扩张段的设计。计算表明,临界锥角随λ的增大而增大,且随粉粒直径d_p的减小而增大。     

Chiral supramolecular gold-cysteine nanoparticles: Chiroptical and nonlinear optical properties

Cysteine is a sulfur-containing amino acid that easily coordinates to soft metal ions and grafts to noble metal surfaces. We report a simple synthetic approach for the production of chiral gold-cysteine polymeric nanoparticles soluble in water. Conjugation of cysteine with gold in a polymeric way, leading to ~50 nm diameter nanoparticles, resulted in the generation of new characteristic circular dichroism (CD) signals in the region of 250–400 nm, whereas no CD signal changes were found with cysteine alone. We also investigate their nonlinear optical properties after two-photon absorption. Two-photon emission spectra and first hyper-polarizabilities, as obtained by the hyper-Rayleigh scattering technique, of these particles are presented.     

The importance of regional geology in the geological theories of Abraham Gottlob Werner: a contrary opinion

It has been and still is commonly believed by geologists and historians of geology alike that geological theory is an extrapolation from the empirical knowledge of the geology of a region. Abraham Gottlob Werner (1749–1817), whose theory concerning the origin of basalt and the minor role of volcanoes and the major role of water in the history of the earth's crust was eventually proven wrong in some respects, is usually cited as the prime example of a geologist who had not ventured beyond the confines of his native region, Saxony, and had developed a universal geological theory based almost entirely on his observations of that region. In this essay I show that the geology of Saxony played a relatively unimportant role in the development of Werner's universal geological theory; that he became a neptunist before he had closely examined the geology of Saxony; and that his explanation of the history of the earth's crust was as reasonable, if not more reasonable, than the explanations brought forth by those of his contemporaries who opposed his views.