Updated precision measurement of the average lifetime of B hadrons

The measurement of the average lifetime of B hadrons using inclusively reconstructed secondary vertices has been updated using both an improved processing of previous data and additional statistics from new data. This has reduced the statistical and systematic uncertainties and gives \tau_{\mathrm{B}} = 1.582 \pm 0.011\ \mathrm{(stat.)} \pm 0.027\ \mathrm{(syst.)}\ \mathrm{ps.} Combining this result with the previous result based on charged particle impact parameter distributions yields \tau_{\mathrm{B}} = 1.575 \pm 0.010\ \mathrm{(stat.)} \pm 0.026\ \mathrm{(syst.)}\ \mathrm{ps.

Behaviour, preferences and cities: urban theory and urban resurgence

The resurgence of big, old cities and their regions is real, but it is merely a part of a broader pattern of urban change in the developed countries, whose broadest tendency is urban emergence, including suburbanisation, and movements of population to certain 'Sunbelt' regions. The problem is that it is difficult to accommodate explanation of both resurgence and emergence using the main explanations in the field today. These include: theories of the knowledge or creative economy, urban amenities, diversity and tolerance, and urban beauty. In most of their common specifications, they do well for either resurgent or emergent cities, but not for both at the same time. This suggests that these ideas, interesting as they are, require much greater specification and, in some cases, overhaul, in order to offer satisfactory responses to the diversity of patterns of urban growth. By examining some of these deficiencies, we conclude that urban theory needs a better understanding of urban choice behaviours and especially the effects of bundling, the limits to preference substitutions and the relationship between past and present preferences, in order to become fully effective in explaining urban resurgence and urban emergence. When these aspects of choice and preference are better integrated into urban theory, then the 'exogenous' causes of urbanisation can be made more endogenous and, in addition, they can be applied better to both emergence and resurgence. Urban research can, by so doing, also potentially become more policy-relevant

WELFARE REFORM: Recent Policy and Politics

Public policy research has not combined policy and political analysis as its pioneers imagined. Mostly, political scientists study just the policy process, abandoning prescriptions to policy specialists. A better approach is to combine policy and political analysis, using positions on issues to assess policymaking, and vice versa. This article illustrates that approach by applying it to recent welfare reform. I take raising work levels as the chief goal of reform and assess the Family Support Act (FSA) of 1988 and the Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA) of 1996 against it. FSA was a timid compromise that achieved little while PRWORA was a conflicted measure that achieved more, but at unnecessary risk. I also ask how the tensions between best policy and politics might be resolved. This approach makes public policy research more relevant to the real stakes in policymaking. [142 words.] Copyright 2002 by The Policy Studies Organization.