Circuit optimization via sequential computer experiments: design of an output buffer

In electrical engineering, circuit designs are now often optimized via circuit simulation computer models. Typically, many response variables characterize the circuit's performance. Each response is a function of many input variables, including factors that can be set in the engineering design and noise factors representing manufacturing conditions. We describe a modelling approach which is appropriate for the simulator's deterministic input–output relationships. Non-linearities and interactions are identified without explicit assumptions about the functional form. These models lead to predictors to guide the reduction of the ranges of the designable factors in a sequence of experiments. Ultimately, the predictors are used to optimize the engineering design. We also show how a visualization of the fitted relationships facilitates an understanding of the engineering trade-offs between responses. The example used to demonstrate these methods, the design of a buffer circuit, has multiple targets for the responses, representing different trade-offs between the key performance measures.     

Curved Chaotic Map Time Series Models and Their Stochastic Reversals

This paper considers two types of chaotic map time series models, including the well-known tent, logistic and binary-shift maps as special cases; these are called curved tent and curved binary families. Deterministic behaviour is investigated by invariant distributions, Lyapunov exponents, and by serial dependency. Stochastic time reversal of the families is shown to produce models which have a broader range of stochastic and chaotic properties than their deterministic counterparts. The marginal distributions may have concentrations and restricted supports and are shown to be a non-standard class of invariant distribution. Dependenc y is generally weaker with the reversed stochastic models. The work gives a broad statistical account of deterministic and stochastically reversed map models, such as are emerging in random number generation, communica tion systems and cryptography     

Income generation and Facts for Life communication in Vietnam

In1997, UNICEF Vietnam conducted a participatory evaluation, Pathways Forward, to assess the impact of the Income Generation and Facts for Life (FFL) Communication Project, which communicates basic health messages to women who are also participating in a revolving loan scheme. Twenty-five people from UNICEF and the Vietnam Womens Union participated in the month-long evaluation. They used a combination of case studies, interviews, surveys, and social indicators to determine the projects impact on women finishing their final loan cycle in two project communes. A second group studied the projects microcredit component in order to recommend a financial strategy for the future.Evaluators found that while the project had successfully met many of its objectives, the degree of its success varied dramatically between the two communes studied. Further, the evaluation found the projects operational capacity needed to be strengthened so as to support existing microcredit activities.Based on these findings, the Pathways evaluation recommended that UNICEF postpone any future loan disbursements and focus instead on building the projects capacity through increased staffing levels and additional training. It also recommended a number of measures be taken to strengthen FFL communication activities, including training for group leaders and simpler, locally-produced FFL materials.     

Institutional Ethnography and Experience as Data

Experience, as concept, is contested among feminists as to its epistemological status, thus its usefulness in knowledge claims. Institutional ethnography (Smith 1987) is a feminist methodology that nonetheless relies fundamentally on people's experience. Not as Truth, nor the object of inquiry, but as thepoint d'appui for sociological inquiry. This article offers a demonstration of institutional enthnography using observational and interview data that show experience as methodologically central to a trustworthy analysis. A moment in the work lives of nursing assistants in a long-term care setting is captured by a participant observer. The analysis produces two lines of argument. One is methodological; it is argued that nursing assistants' experiences are an entry into the social relations of the setting that, when mapped and disclosed, make those experiences understandable in terms of the ruling arrangements permeating both the organization and their own experiences. The other argument is substantive; the inquiry uncovers how a quality improvement' strategy in a long term care hospital in Canada is reorganizing caregivers' values and practices toward a market orientation in which care appears to be compromised. Use of experience as data in this approach holds the analysis accountable to everyday/everynight actualities in a lived world.     

Fit and Skill in Employee Selection: Insights from a Study of Headhunters

We draw upon evidence from a qualitative study of headhunters to provide insights into the character and importance of candidate fit and skill for the selection of a broad range of white-collar employees. Headhunters suggest that the fit of a job candidate is assessed at two levels, one corresponding with a general compatibility with organization-level norms, culture, and strategy, the other corresponding more closely with traits and characteristics of the person or persons with whom the job candidate actually interviews. Skill—a factor which is largely neglected by those who tout the importance of fit—also plays an important and independent role in employee selection. Stalls that influence the selection of employees from a pool of candidates tend to be highly specific if not idiosyncratic, and take the form of what headhunters call hot buttons. We conclude by discussing the conceptualization, causes, and implications of fit; we also consider how the importance of fit and hot buttons challenges the explanatory logic of standard accounts of labor-market success.     

Statistical Methods and Graphical Displays for Analyzing How the Association Between Two Qualitative Variables Differs Among Countries, Among Groups, Or Over Time: A Modified Regression-Type Approach

Many interesting sociological questions pertain to how the association between two variables depends on a third variable. In sociological applications, the third variable often pertains to countries, to subgroups of a population, or to time periods. We propose a regression-type approach that specifies that the log-odds- ratios that describe the two-way association of interest are a linear function of latent scores for the third variable. Additive and multiplicative models currently in use by researchers are special cases of the regression-type model. To illustrate the utility of the regression-type approach, we apply this approach to analyze (1) data on occupational mobility in the United States, Britain, and Japan (comparing mobility in these countries) and (2) data on the association between religion and voting behavior in U.S. presidential elections from 1968 to 1992 (comparing this association in the different elections). We also introduce here graphical displays that can be used to obtain worthwhile information about goodness-of-fit and to aid in substantive interpretation.     

Severely Traumatized Siblings: A Treatment Strategy

Siblings who have suffered severe trauma and disrupted attachment relate to one another in ways that interfere with individual development, the chance to benefit from connections with adults, the establishment of healthy sibling relationships, and the working through of traumatic experiences. The authors use case examples to illustrate four distinct sibling patterns: absent, adult lockout, half and half, and trauma shield. The authors highlight the importance of recognizing these types and then varying the therapist's treatment stance to pursue five goals. These include suspending problematic sibling relationships to create room for bonding with caring adults, transferring attachment behaviors and impulses to a receptive adult, resuming healthy individual development, forming more adaptive sibling connections, and expressing shared traumatic content.     

AN EVOLUTIONARY EXPLANATION FOR ROTTEN KIDS

We explore how natural selection acts upon genes for cooperation, altruism and selfishness in an prisoner's dilemma played by family members. A key parameter determining behavior is that parents and children have different expectations of future offspring. Examining asexual and sexually reproducing populations we show that which strategy of cooperation and defection proves be stable depends on the relative reproduction potential of the players and what proportion of the population is young. "Rotten kids" with altruistic parents can be a stable outcome where reproductive success is the goal, and natural selection may lead individuals to care about their unborn progeny. (JEL D10, H31)     

ELASTIC CAPITAL SUPPLY AND THE EFFECTS OF FISCAL POLICY

Existing analyses of the effects of fiscal policy in general equilibrium models have typically been conducted under the assumption that the long-run supply of capital is perfectly elastic at a fixed rate of time preference. These analyses have shown that the long-run response of the capital stock to changes in fiscal policy is crucial to generating the potential for “multiplier” effects in these models. In this paper we ask, what are the implications of relaxing the assumption of perfectly elastic capital supply for the analysis of fiscal policy? We show that with less than perfectly elastic capital supply, the potential for multipliers is actually enhanced. (JEL E62, D90)