Commitment in intertemporal household consumption: a revealed preference analysis

We present a revealed preference methodology for analyzing intertemporal household consumption behavior. In doing so, we follow a collective approach, which explicitly recognizes that multi-member households consist of multiple decision makers with their own rational preferences. Following original work of Mazzocco (2007), we develop tests that can empirically verify whether observed consumption behavior is consistent with (varying degrees of) intrahousehold commitment. In our set-up, commitment means that households choose consumption allocations on the ex ante Pareto frontier. The distinguishing feature of our tests is that they are entirely nonparametric, i.e. their implementation does not require an a priori (typically non-verifiable) specification of the intrahousehold decision process (e.g. individual utilities). We demonstrate the practical usefulness of our methodology by means of an empirical application. For the data at hand, our results suggest using a so-called limited commitment model that allows for household-specific commitment patterns. Importantly, our application also shows that bringing intertemporal dynamics in the empirical analysis can substantially increases the discriminatory power of the revealed preference methodology.

Opening the 'black box' of efficiency measurement: input allocation in multi-output settings.

We develop a new Data Envelopment Analysis (DEA)-based methodology for measuring the efficiency of Decision Making Units (DMUs) characterized by multiple inputs and multiple outputs. The distinguishing feature of our method is that it explicitly includes information about output-specific inputs and joint inputs in the efficiency evaluation. This contributes to opening the „black box‟ of efficiency measurement in two different ways. First, including information on the input allocation substantially increases the discriminatory power of the efficiency measurement. Second, it allows to decompose the efficiency value of a DMU into output-specific efficiency values which facilitates the identification of the outputs the manager should focus on to remedy the observed inefficiency. We demonstrate the usefulness and managerial implications of our methodology by means of a unique dataset collected from the Activity Based Costing (ABC) system of a large service company with 290 DMUs.

Opening the 'black box' of efficiency measurement: input allocation in multi-output settings

We develop a new Data Envelopment Analysis (DEA)-based methodology for measuring the efficiency of Decision Making Units (DMUs) characterized by multiple inputs and multiple outputs. The distinguishing feature of our method is that it explicitly includes information about output-specific inputs and joint inputs in the efficiency evaluation. This contributes to opening the „black box? of efficiency measurement in two different ways. First, including information on the input allocation substantially increases the discriminatory power of the efficiency measurement. Second, it allows to decompose the efficiency value of a DMU into output-specific efficiency values which facilitates the identification of the outputs the manager should focus on to remedy the observed inefficiency. We demonstrate the usefulness and managerial implications of our methodology by means of a unique dataset collected from the Activity Based Costing (ABC) system of a large service company with 290 DMUs.

Heuristics for deciding collectively rational consumption behavior.

We consider the computational problem of testing whether observed household consumption behavior satisfies the Collective Axiom of Revealed Preferences (CARP). We propose a graph such that the existence of a node-partitioning giving rise to two induced subgraphs that are acyclic implies that the data satisfy CARP. Furthermore, we propose and implement heuristics that are quite fast, that can be used to check reasonably large datasets for CARP and that can be of particular interest when used prior to computationally demanding approaches. Finally, from the computational results we conclude that these heuristics can be effective in testing CARP.Collective model of household consumption; Collective Axiom of Revealed; Preference; Pareto efficiency; Directed graph; Graph coloring; Graph partitioning; Acyclic subgraph; Heuristics;

Heuristics for deciding collectively rational consumption behavior

We consider the computational problem of testing whether observed household consumption behavior satisfies the Collective Axiom of Revealed Preferences (CARP). We propose a graph such that the existence of a node-partitioning giving rise to two induced subgraphs that are acyclic implies that the data satisfy CARP. Furthermore, we propose and implement heuristics that are quite fast, that can be used to check reasonably large datasets for CARP and that can be of particular interest when used prior to computationally demanding approaches. Finally, from the computational results we conclude that these heuristics can be effective in testing CARP.Collective model of household consumption; Collective Axiom of Revealed Preference; Pareto efficiency; Directed graph; Graph coloring; Graph partitioning; Acycli subgraph; Heuristics.

Nonparametric tests of collectively rational consumption behavior: an integer programming procedure

We present an IP-based nonparametric (revealed preference) testing procedure for rational consumption behavior in terms of a general collective model, which includes consumption externalities and public consumption. An empirical application to data drawn from the Russia Longitudinal Monitoring Survey (RLMS) demonstrates the practical usefulness of the procedure. Finally, we present extensions of the testing procedure to evaluate the goodness-of-fit (accounting for optimization error as well as measurement error) of the collective model subject to testing

Diversity and Habitat Specificity of Free-Living Protozoa in Commercial Poultry Houses

Despite stringent biosecurity measures, infections by bacterial food pathogens such as Campylobacter are a recurrent problem in industrial poultry houses. As the main transmission route remains unclear, persistence of these infections has been linked to bacterial survival and possibly multiplication within protozoan vectors. To date, however, virtually no information is available on the diversity and occurrence of free-living protozoa in these environments. Using a combination of microscopic analyses of enrichment cultures and molecular methods (denaturing gradient gel electrophoresis [DGGE]) on natural samples, we show that, despite strict hygiene management, free-living protozoa are common and widespread throughout a 6-week rearing period in both water and dry samples from commercial poultry houses. Protozoan communities were highly diverse (over 90 morphotaxa and 22 unique phylotypes from sequenced bands) and included several facultative pathogens and known bacterial vectors. Water samples were consistently more diverse than dry ones and harbored different communities, mainly dominated by flagellates. The morphology-based and molecular methods yielded markedly different results: amoebic and, to a lesser degree, ciliate diversity was seriously underestimated in the DGGE analyses, while some flagellate groups were not found in the microscopic analyses. Some recommendations for improving biosecurity measures in commercial poultry houses are suggested

Physiological and transcriptomic evidence for a close coupling between chloroplast ontogeny and cell cycle progression in the pennate diatom Seminavis robusta

Despite the growing interest in diatom genomics, detailed time series of gene expression in relation to key cellular processes are still lacking. Here, we investigated the relationships between the cell cycle and chloroplast development in the pennate diatom Seminavis robusta. This diatom possesses two chloroplasts with a well-orchestrated developmental cycle, common to many pennate diatoms. By assessing the effects of induced cell cycle arrest with microscopy and flow cytometry, we found that division and reorganization of the chloroplasts are initiated only after S-phase progression. Next, we quantified the expression of the S. robusta FtsZ homolog to address the division status of chloroplasts during synchronized growth and monitored microscopically their dynamics in relation to nuclear division and silicon deposition. We show that chloroplasts divide and relocate during the S/G2 phase, after which a girdle band is deposited to accommodate cell growth. Synchronized cultures of two genotypes were subsequently used for a cDNA-amplified fragment length polymorphism-based genome-wide transcript profiling, in which 917 reproducibly modulated transcripts were identified. We observed that genes involved in pigment biosynthesis and coding for light-harvesting proteins were up-regulated during G2/M phase and cell separation. Light and cell cycle progression were both found to affect fucoxanthin-chlorophyll a/c-binding protein expression and accumulation of fucoxanthin cell content. Because chloroplasts elongate at the stage of cytokinesis, cell cycle-modulated photosynthetic gene expression and synthesis of pigments in concert with cell division might balance chloroplast growth, which confirms that chloroplast biogenesis in S. robusta is tightly regulated