The debt trap: A two-compartment train wreck… and how to avoid it

We explore sustainable paths out of a debt trap with a highly stylized two-sector differential equations model for the stocks of money in Government and Society. The model fits the data for the U.S. between 1981 and 2012 with a coefficient of correlation of 0.996. The solutions provide detailed “escape conditions” from the debt trap. A primary surplus is required. Then a government can escape its debt trap either through sustained annual monetary outflows from society to the government (taxation) but with a low initial growth rate, or through annual monetary inflows into both sectors (stimulus) with higher initial growth rate. We illustrate the use of our model with simulations which show how five indebted countries can escape their debt trap in 30 (or 70) years.     

A Quality Risk Management Model Approach for Cell Therapy Manufacturing

International regulatory authorities view risk management as an essential production need for the development of innovative, somatic cell‐based therapies in regenerative medicine. The available risk management guidelines, however, provide little guidance on specific risk analysis approaches and procedures applicable in clinical cell therapy manufacturing. This raises a number of problems. Cell manufacturing is a poorly automated process, prone to operator‐introduced variations, and affected by heterogeneity of the processed organs/tissues and lot‐dependent variability of reagent (e.g., collagenase) efficiency. In this study, the principal challenges faced in a cell‐based product manufacturing context (i.e., high dependence on human intervention and absence of reference standards for acceptable risk levels) are identified and addressed, and a risk management model approach applicable to manufacturing of cells for clinical use is described for the first time. The use of the heuristic and pseudo‐quantitative failure mode and effect analysis/failure mode and critical effect analysis risk analysis technique associated with direct estimation of severity, occurrence, and detection is, in this specific context, as effective as, but more efficient than, the analytic hierarchy process. Moreover, a severity/occurrence matrix and Pareto analysis can be successfully adopted to identify priority failure modes on which to act to mitigate risks. The application of this approach to clinical cell therapy manufacturing in regenerative medicine is also discussed.     

A comparison of risk transfer strategies for a portfolio of life annuities based on RORAC

This paper aims to compare different reinsurance arrangements in order to reduce the longevity and financial risk originated by a life insurer while managing a portfolio of annuities policies. Linear and nonlinear reinsurance strategies as well as swap like agreements are evaluated via a discrete-time actuarial risk model. Specifically, longevity dynamics are represented by Lee–Carter type models, while interest rate is modeled by Cox–Ingersoll–Ross model. The reinsurance strategies effectiveness is evaluated according to the Return on Risk Adjusted Capital under a ruin probability constrain.     

Threshold‐free estimation of functional antibody titers of a group B streptococcus opsonophagocytic killing assay

Opsonophagocytic killing assays (OPKA) are routinely used for the quantification of bactericidal antibodies in blood serum samples. Quantification of the OPKA readout, the titer, provides the basis for the statistical analysis of vaccine clinical trials having functional immune response endpoints. Traditional OPKA titers are defined as the maximum serum dilution yielding a predefined bacterial killing threshold value, and they are estimated by fitting a dose‐response model to the dilution‐killing curve. This paper illustrates a novel definition of titer, the threshold‐free titer, which preserves biological interpretability while not depending on any killing threshold or on a postulated shape of the dose‐response curve. These titers are shown to be more precise than the traditional threshold‐based titers when using simulated and experimental group B streptococcus OPKA experimental data. Also, titer linearity is shown to be not measurable when using threshold‐based titers, whereas it becomes measurable using threshold‐free titers. The biological interpretability and operational characteristics demonstrated here indicate that threshold‐free titers are an appropriate tool for the routine analysis of OPKA data. Copyright © 2015 John Wiley & Sons, Ltd.     

The Top-Down/Bottom-Up Controversy from a Constructionist Approach. A Method for Measuring Top-Down Effects Applied to a Sample of Older People

Two different theories, called bottom-up and top-down, were developed to understand the determinants of an individual's satisfaction. Experimental studies didn't provide unanimous results, and confirmed, to different extents, both theories. Aside from these classic theories, a constructionist approach was developed. The purposes of this study were to examine the top-down/bottom-up controversy from a constructionist point of view and to obtain a new method for measuring the top-down effects in different satisfaction judgements. In this approach, an individual's satisfaction is viewed as constructions, evoked by the specific question in its particular context, and made by people using cognitive strategies. This view implies that the correlation between satisfaction judgements may reflect the use of the same strategies, rather than a causal effect. From this point of view, the top-down and bottom-up effects, described by the classic theories, cannot be seen as a pattern of causal links among satisfaction domains; therefore we propose a reinterpretation of these concepts in which they refer to ways used by people to construct their satisfaction judgements. On these grounds, we developed a method to extract the weight of top-down effects from correlation coefficients between satisfaction judgements. Two hypotheses concerning the different weight of top-down processes in the different satisfaction judgements were subsequently developed.These propositions were tested using the data set of 'Outdoor Mobility Survey' which was carried out in Italy on a sample of 600 people, 55--95 years of age, stratified by sex and age. We found different top-down effects in satisfaction judgements that confirm our hypothesis, even if some aspects need further investigation.     

Perceptions and expectations of price changes and inflation: A review and conceptual framework

Drawing on relevant literature from a diverse range of academic disciplines we present a conceptual framework intended to further our understanding of perceptions and expectations of price changes and inflation. Based on this framework, we provide a detailed review of the literature and an analysis of open issues in current research. The review is primarily concerned with individuals’ perceptions and expectations of price changes and inflation, which can influence individuals’ economic behaviour (e.g. spending and saving decisions). The main insight from the review is that while consumers may have a limited ability to store and recall specific prices, and even succumb to a number of biases in the way in which they form perceptions and expectations of global price changes, they do seem to have some feel for, and ability to judge and forecast, inflation. How they achieve this, however, is still an open question, although plausible explanations have been proposed. While much important research has been undertaken and significant progress made in our understanding of the psychology of inflation, there remain many unanswered questions and interesting avenues for future research, which are discussed in the final part of the paper.     

Algebraic exact inference for rater agreement models

In recent years, a method for sampling from conditional distributions for categorical data has been presented by Diaconis and Sturmfels. Their algorithm is based on the algebraic theory of toric ideals which are used to create so called “Markov Bases”. The Diaconis-Sturmfels algorithm leads to a non-asymptotic Monte Carlo Markov Chain algorithm for exact inference on some classes of models, such as log-linear models. In this paper we apply the Diaconis-Sturmfels algorithm to a set of models arising from the rater agreement problem with special attention to the multi-rater case. The relevant Markov bases are explicitly computed and some results for simplify the computation are presented. An extended example on a real data set shows the wide applicability of this methodology. Partially supported by MIUR Cofin03 (G. Consonni) and by INdAM projectAlgebraic Statistics.     

Leadership in education: Effective U.K. college principals

College leaders face increasing challenges to manage complex responsibilities. They must possess a wide variety of managerial and leadership skills to be successful in academic environments, which are beginning to resemble more traditional organizational frameworks. The study examined in this article explored the relationships among managerial style, organizational climate, and several measures of college‐student performance with a sample of British further education college principals (similar to U.S. community college presidents). While considering the influence of various background factors, such as the size of the college, student funding, and years of experience, several significant relationships emerged demonstrating a significant association between principals' managerial behaviors and measures of college and student performance.