Nonlinear voxel-based modelling of the haemodynamic response in fMRI

A common assumption for data analysis in functional magnetic resonance imaging is that the response signal can be modelled as the convolution of a haemodynamic response (HDR) kernel with a stimulus reference function. Early approaches modelled spatially constant HDR kernels, but more recently spatially varying models have been proposed. However, convolution limits the flexibility of these models and their ability to capture spatial variation. Here, a range of (nonlinear) parametric curves are fitted by least squares minimisation directly to individual voxel HDRs (i.e., without using convolution). A ‘constrained gamma curve’ is proposed as an efficient form for fitting the HDR at each individual voxel. This curve allows for spatial variation in the delay of the HDR, but places a global constraint on the temporal spread. The approach of directly fitting individual parameters of HDR shape is demonstrated to lead to an improved fit of response estimates.     

A comparison of two procedures to select the best binomial population with sequential elimination of inferior populations

We compare the selection procedure of Levin and Robbins [1981. Selecting the highest probability in binomial or multinomial trials. Proc. Nat. Acad. Sci. USA 78, 4663–4666.] with the procedure of Paulson [1994. Sequential procedures for selecting the best one of k Koopman–Darmois populations. Sequential Analysis 13, 207–220.] to identify the best of several binomial populations with sequential elimination of unlikely candidates. We point out situations in which the Levin–Robbins procedure dominates the Paulson procedure in terms of the duration of the experiment, the expected total number of observations, and the expected number of failures. Because the Levin–Robbins procedure is also easier to implement than Paulson's procedure and gives a tighter guarantee for the probability of correct selection, we conclude that it holds a competitive edge over Paulson's procedure.     

The impact of organizational culture and leadership performance on PR professionals’ job satisfaction: Testing the joint mediating effects of engagement and trust

The study examines the impact of critical organizational factors (organizational culture and excellent leader performance) on public relations professionals’ overall job satisfaction by focusing on testing the joint mediating effects work engagement and trust could generate. A national online survey of 838 public relations professionals working in a variety of organizations was used as the empirical data to test the relationships in a proposed conceptual model. Results confirmed the strong impact organizational culture and leader performance could have on public relations professionals’ work engagement, trust, and job satisfaction. More importantly, results revealed the significant joint mediating effects of engagement and trust on professionals’ job satisfaction, when supportive organizational culture and excellent leader performance were achieved. The study concludes with research and practical implications.     

Classification-Error Models and Labor-Market Dynamics

Measurement error is often a severe problem in longitudinal data such as labor-market flows. Two correction methods have been used for labor-market flows, but the methods tend to adjust the data in opposite directions. One method shows a rigid labor market with long unemployment spells, whereas the other shows the opposite. Because the methods appear theoretically similar, one might interpret the differing results as an indictment of both procedures. This article documents and explains the differences between the two methods. More important, it argues that the differences result from the reliance of one method on assumptions that are theoretically implausible and rejected by the data.     

Postmodernism: A Dead End in Social Work Epistemology

Postmodernism continues to have a detrimental influence on social work, questioning the Enlightenment, criticizing established research methods, and challenging scientific authority. The promotion of postmodernism by editors of Social Work and the Journal of Social Work Education has elevated postmodernism, placing it on a par with theoretically guided and empirically based research. The inclusion of postmodernism in the 2008 Educational Policy and Accreditation Standards of the Council on Social Work Education and its 2015 sequel further erode the knowledge-building capacity of social work educators. In relation to other disciplines that have exploited empirical methods, social work’s stature will continue to ebb until postmodernism is rejected in favor of scientific methods for generating knowledge.     

Survival Distributions Satisfying Benford's Law

Hill stated that “An interesting open problem is to determine which common distributions (or mixtures thereof) satisfy Benford's law …”. This article quantifies compliance with Benford's law for several popular survival distributions. The traditional analysis of Benford's law considers its applicability to datasets. This article switches the emphasis to probability distributions that obey Benford's law.     

Intended and initial settlement patterns of recent immigrants to the U.S., 1985–1990: A comparison of PUMS and INS public use files

At the time of entry into the U.S., immigrants are required to identify their ’intended’ destination to INS officials. They are not, however, required to remain in that location. If immigrant settlement patterns represent an evolutionary, dynamic system, it is likely that immigrants will adjust their location in the period shortly after arrival in the U.S. in response to various factors, leading to an ‘initial’ settlement system. Of interest in the following paper are the scale, direction and magnitude of adjustments made to the immigrant settlement system in the period shortly after arrival. The analysis utilizes the 1990 5 percent Public Use Microdata Sample (PUMS) and the 1985–90 Immigration and Naturalization Service (INS) Public Use Tapes in order to explore the intended and initial (observed) settlement patterns of recent (1985–90) immigrants and to comment upon the applicability of these terms. Results indicate that the two settlement patterns are highly similar, despite apparently high levels of movement among recent arrivals. The analysis also touches upon the ‘come to stay’ question raised by Ellis and Wright (1998a), suggesting that the interpretation of the question is dependent upon immigrant status rather than when immigrants first arrived in the U.S. This research was funded by a grant from the National Science Foundation (97-08436). The author is solely responsible for the content of this research.     

Between argument and coercion: Social coordination in rural environmental governance

Increasingly, partnerships and other cooperative forms of governance are common-place in addressing problems of environmental management in rural landscapes. These forms of governance are multi-dimensional in the policy instruments employed; the make-up of actors; and, the types of rationalities that actors use to debate the problem and proposed solutions. This paper pursues the question of how different modes of social action, represented in argumentative claims of participants, influence social coordination in these governance arenas. An empirical study is presented of agri-environmental governance in Australia where actors debate planning and policy initiatives to reduce diffuse water quality impacts from farms on the adjacent Great Barrier Reef. Forester’s conceptualisation of practical social action which locates communicative action in the ‘real world’ of interest-based planning contexts, is used as an analytical frame to identify: (i) the type of claims made by governments, farmer groups and other actors in argumentation; (ii) the claims association with communicative, strategic and instrumental modes of action; and, (iii) their consequence for social coordination in formation and maintenance of inclusive, legitimate and viable forms of governing. The study finds that the interconnected character of claims made by actors, and the ready switching between modes of action observed, point to a situated and dynamic expression of rationality within these contested and prolonged debates on how to legitimately and effectively govern rural environments.