面向全体学生的物理——2006年美国全国物理教师协会"密立根奖"受奖演讲

我们物理教师必须将关注点从“面向物理学家和其他科学家的物理”扩大到“面向全体学生的物理”．理由正如美国科学促进协会说的那样：“没有一个具备科学素养的大众，美好世界的前景就没有指望．”面向全体学生的物理（包括为培养科学家而开设的初级课程）应该是概念性的，而不是技术性的．它应该把宇宙描述为我们今天所了解的宇宙，包括狭义和广义相对论、量子物理、近代宇宙学、核物理、粒子和相互作用的标准模型，以及量子场论．许多科学著作者已经向我们展示这是可以实现的．面向全体学生的物理应该强调科学的过程，并包含如全球变暖、核武器和伪科学等社会性话题，因为公众需要对这些问题做出明智的表决．     

Financial Modelling on Microcomputers

The financial modelling packages for microcomputers can be considered as falling into one of three categories:- visual spread sheets, micro base structured models and structured models which are compatible across, and allow communications between, micros and mainframes. This paper describes the three types of package, discusses the pros and cons of each, and offers a guide to system selection.     

The interpretation of inductive probabilities

An apparent inconsistency in the inductive logic interpretation of probabilities is examined and resolved.Supported by a grant from the National Science Foundation.     

A new theorem of information theory

Consider a random experiment whose possible outcomes arez ₁,z ₂,...,z _n. Let the prior probabilities be p₁ ⁰, ...,p_n ⁰, and let the posterior probabilities bep ₁,...,p _n. It is shown that, subject to certain prescribed and intuitively reasonable conditions, the expressionI =k p _i In (p _i/p _i ⁰), wherek is a positive constant, is the unique expression for the information contained in a message which alters the probabilities from thep _i ⁰ to thep _i.     

Renal structure in neotropical bats: using stable isotopes to explore relationships between diet and morphology

The relationship between kidney structure and diet was examined in several species of bats from the tropics. The trophic level of the bats was determined by their stable nitrogen isotopic composition (delta15 N). The results indicate that the relative thickness of the renal medulla is directly related to the trophic level of the bats. Additionally, we also determined the relationship between body mass and kidney structure. Relative medullary thickness was reciprocally related to body mass in animalivorous bats but no relationship was found in phytophagous bats. Stable isotope analysis provided a quantitative approximation of diet to test its relationship with kidney structure.     

Electron spin polarization of the excited quartet state of strongly coupled triplet-doublet spin systems

The electron spin polarization associated with electronic relaxation in molecules with trip-quartet and trip-doublet excited states is calculated. Such molecules typically relax to the lowest trip-quartet state via intersystem crossing from the trip doublet, and it is shown that when spin-orbit coupling provides the main mechanism for this relaxation pathway it leads to spin polarization of the trip quartet. Analytical expressions for this polarization are derived using first- and second-order perturbation theory and are used to calculate powder spectra for typical sets of magnetic parameters. It is shown that both net and multiplet contributions to the polarization occur and that these can be separated in the spectrum as a result of the different orientation dependences of the +/-1/2<-->+/-3/2 and +1/2<-->-1/2 transitions. The net polarization is found to be localized primarily in the center of the spectrum, while the multiplet contribution dominates in the outer wings. Despite the fact that the multiplet polarization is much stronger than the net polarization for individual orientations of the spin system, the difference in orientation dependence of the transitions leads to comparable amplitudes for the two contributions in the powder spectrum. The influence of this difference on the line shape is investigated in simulations of partially ordered samples. Because the initial nonpolarized state of the spin system is not conserved for the proposed mechanism, the net polarization can survive in the doublet ground state following electronic relaxation of the triplet part of the system.     

Raman spectroscopic analysis of breast cancer tissues: identifying differences between normal,invasive ductal carcinoma and ductal carcinoma in situ of the breast tissue

A relatively non‐destructive method employing Raman spectroscopy for the analysis of histopathological specimens is described. Raman spectroscopy has allowed qualitative analysis of the same specimen used for histopathological evaluation. Breast cancer tissues have been analysed to demonstrate the feasibility of the chemical changes taking place in the biological tissue, which can be identified precisely, and the results are reproducible. Raman analysis of tissue sections provides distinct spectra that can be used to distinguish between the nuclear grades of ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) of the breast. Sixty cases of breast carcinoma including DCIS and IDC and seven cases of normal breast tissues were studied employing the Raman spectroscopic technique. This study reports for the first time spectral differences between DCIS grades. It is concluded that Raman spectroscopy can objectively distinguish between DCIS and IDC grades and is non‐destructive and reproducible. It should become possible in future to use Raman spectroscopy as an informative and quantitative method suitable for classification of grades and diagnosis of breast carcinoma. Copyright © 2007 John Wiley & Sons, Ltd.     

Promising X-ray fluorescence tests for superconducting tunnel junction detector

The Advanced Photon Source (APS) looks forward to a period of growth in the coming years. Meanwhile, in April 2006, the APS reorganized its divisions, creating an X-ray Science Division (XSD), bringing science at the APS on a par with the accelerator, and sharing engineering and support services. The machine division, the Accelerator Systems Division, now includes all of the groups that operate and develop the machine and focus on future accelerator research.