Determination of Electronic Energy Levels of Molecules by Low-Energy Electron Impact Spectroscopy

This paper describes a new spectroscopic tool in which optically forbidden electronic transitions can usually be detected as clearly as optically allowed ones in a fairly routine manner. It uses the inelastic scattering of low-energy electrons by molecules as the means for determining their electronic energy levels

Differences between Low-Energy Electron Impact Spectra at 0º and at Large Scattering Angle

The preceding Comment reports some low-energy electron-impact spectra of helium and ethylene, obtained by a very elegant technique, which are markedly different from the ones we obtained 1 under other experimental conditions. It is quite important to try to understand the reasons for the differences observed. These differences are essentially the following: (a) In our impact spectra of helium obtained with 50-eV electrons we observe pronounced peaks corresponding to the 2 ^3S state and to ionization whereas Simpson and Mielczarek do not. (b) In our spectra of ethylene at this same incident electron energy we observe two pronounced optically forbidden transitions an

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A theory of trade concessions

Cataloged from PDF version of article.We present a model of tariff disputes and concessions consisting of an infinitely repeated game under bilateral incomplete information. Given potential agreements to be reached through unilateral or reciprocal concessions, we find that an agreement involving reciprocal concessions is reached immediately if the discount factor is large and/or the volume of trade is small. Otherwise prior beliefs about country type matter: when both countries hold pessimistic priors, immediate reciprocal concessions still occur. Very different prior beliefs lead to an immediate unilateral concession of the pessimistic country, whereas optimistic priors coupled with low discount factors may generate delayed agreements. (C) 1997 Elsevier Science B.V

Risk Management in an Age of Change

The environment in which banks and other financial services industry firms operate was once very stable. It is now increasingly permeated with change. Enhanced performance demands make this change salient to high-level decision-makers. Many of the opportunities firms now face are path-dependent and this will continue to be so. For firms to make effective choices in such an environment, both competitive strategy and the strategy-making process must come to terms with opportunities which evolve over time. Old decision-making systems and attitudes are unhelpful in this and may even be impediments to good outcomes. Risk inevitably features in getting these decisions right. All strategic decisions induce and impose constraints on the types of risk banks traditionally monitor and manage. This needs to be explicitly considered and is generally not. Strategic decisions also impose a new type of risk, detailed here, which also needs to be analyzed, monitored, and controlled. All these activities require changes, discussed in detail, both in decision-making protocols and in the organizational structures and routines supporting decision-making

Electron-Impact Spectroscopy

A spectrometer has been devised for determining electronic energy levels of molecules by inelastic scattering of low-energy electrons. It permits the detection of optically forbidden electronic transitions as clearly as optically allowed ones in a routine manner. The spectrometer has been used to obtain excitation spectra for helium, argon, hydrogen and ethylene. For the first three of these substances, the spectra agree with previous experiments. For ethylene, in addition to optically allowed transitions, two forbidden ones occur at about 4-6 and 6-5eV. Variation of peak heights with incident electron beam energy suggest that the first corresponds to a triplet state but that the second does not

Real Estate Prices in Beijing, 1644 to 1840

This paper provides the first estimates of housing price movements for Beijing in late pre-modern China. We hand-collect from archival sources transaction prices and other house attribute information from the 498 surviving house sale contracts for Beijing during the first two centuries of the Qing Dynasty (1644–1840), a long period without major wars, political turmoil, or significant institutional change in the Chinese capital. We use hedonic methods to construct a real estate price index for Beijing for the period. The regression analysis explains a major proportion of the variance of housing prices. We find that house prices grew steadily for the first half-century of the Qing Dynasty and declined afterwards in both nominal and real terms through the late eighteenth century. Nominal prices grew starting in the late eighteenth century and declined from the early nineteenth century through 1840. But these price changes occurred with contemporaneous price changes in basic measures of the cost of living: there was little change in real terms to the end of our period

Spinal cord stimulation for the management of pain: Recommendations for best clinical practice

Spinal cord stimulation (SCS) is an accepted method of pain control. SCS has been used for many years and is supported by a substantial evidence base. A multidisciplinary consensus group has been convened to create a guideline for the implementation and execution of an SCS programme for South Africa (SA). This article discusses the evidence and appropriate context of SCS delivery, and makes recommendations for patient selection and appropriate use. The consensus group has also described the possible complications following SCS. This guideline includes a literature review and a summary of controlled clinical trials of SCS. The group notes that, in SA, SCS is performed mainly for painful neuropathies, failed back surgery, and chronic regional pain syndrome. It was noted that SCS is used to treat other conditions such as angina pectoris and ischaemic conditions, which have therefore been included in this guideline. These recommendations give guidance to practitioners delivering this treatment, to those who may wish to refer patients for SCS, and to those who care for patients with stimulators in situ. The recommendations also provide a resource for organisations that fund SCS. This guideline has drawn on the guidelines recently published by the British Pain Society, and parts of which have beenreproduced with the society’s permission. These recommendations have been produced by a consensus group of relevant healthcare professionals. Opinion from outside the consensus group has been incorporated through consultation with representatives of all groups for whom these  recommendations have relevance. The recommendations refer to the current body of evidence relating to SCS. The consensus group wishes to acknowledge and thank the task team of the British Pain Society for their help and input into this document