A dialectical approach to theoretical integration in developmental-contextual identity research

Future advances in identity research will depend on integration across major theoretical traditions. Developmental-contextualism has established essential criteria to guide this effort, including specifying the context of identity development, its timing over the life course, and its content. This article assesses four major traditions of identity research - identify status, eudaimonic identity, sociocultural theory, and narrative identity - in light of these criteria, and describes the contribution of each tradition to the broader enterprise of developmental-contextual research. This article proposes dialectical integration of the four traditions, for the purpose of generating new questions when the tensions and contradictions among theoretical traditions are acknowledged. We provide examples from existing literature of the kinds of research that could address these questions and consider ways of addressing the validity issues involved in developmental-contextual identity research

Transition from Knudsen to molecular diffusion in activity of absorbing irregular interfaces

We investigate through molecular dynamics the transition from Knudsen to molecular diffusion transport towards 2d absorbing interfaces with irregular geometry. Our results indicate that the length of the active zone decreases continuously with density from the Knudsen to the molecular diffusion regime. In the limit where molecular diffusion dominates, we find that this length approaches a constant value of the order of the system size, in agreement with theoretical predictions for Laplacian transport in irregular geometries. Finally, we show that all these features can be qualitatively described in terms of a simple random-walk model of the diffusion process.Comment: 4 pages, 4 figure

In Vivo Biotinylation of the Toxoplasma Parasitophorous Vacuole Reveals Novel Dense Granule Proteins Important for Parasite Growth and Pathogenesis.

UnlabelledToxoplasma gondii is an obligate intracellular parasite that invades host cells and replicates within a unique parasitophorous vacuole. To maintain this intracellular niche, the parasite secretes an array of dense granule proteins (GRAs) into the nascent parasitophorous vacuole. These GRAs are believed to play key roles in vacuolar remodeling, nutrient uptake, and immune evasion while the parasite is replicating within the host cell. Despite the central role of GRAs in the Toxoplasma life cycle, only a subset of these proteins have been identified, and many of their roles have not been fully elucidated. In this report, we utilize the promiscuous biotin ligase BirA* to biotinylate GRA proteins secreted into the vacuole and then identify those proteins by affinity purification and mass spectrometry. Using GRA-BirA* fusion proteins as bait, we have identified a large number of known and candidate GRAs and verified localization of 13 novel GRA proteins by endogenous gene tagging. We proceeded to functionally characterize three related GRAs from this group (GRA38, GRA39, and GRA40) by gene knockout. While Δgra38 and Δgra40 parasites showed no altered phenotype, disruption of GRA39 results in slow-growing parasites that contain striking lipid deposits in the parasitophorous vacuole, suggesting a role in lipid regulation that is important for parasite growth. In addition, parasites lacking GRA39 showed dramatically reduced virulence and a lower tissue cyst burden in vivo Together, the findings from this work reveal a partial vacuolar proteome of T. gondii and identify a novel GRA that plays a key role in parasite replication and pathogenesis.ImportanceMost intracellular pathogens reside inside a membrane-bound vacuole within their host cell that is extensively modified by the pathogen to optimize intracellular growth and avoid host defenses. In Toxoplasma, this vacuole is modified by a host of secretory GRA proteins, many of which remain unidentified. Here we demonstrate that in vivo biotinylation of proximal and interacting proteins using the promiscuous biotin ligase BirA* is a powerful approach to rapidly identify vacuolar GRA proteins. We further demonstrate that one factor identified by this approach, GRA39, plays an important role in the ability of the parasite to replicate within its host cell and cause disease

Economic impact of port activity : a disaggregate analysis. The case of Antwerp

The economic impact of the port sector is usually measured at an aggregate level by indicators such as value added, employment and investment. This paper tries to define the economic relevance for the regional as well as for the national economy at a disaggregate level. It attempts to identify, quantify and locate the mutual relationships between the various port players themselves and between them and other Belgian industries. Due to a lack of information foreign trade is only tackled very briefly but the method outlined in this paper can be used to measure the national effects of changes in port activity at a detailed level. A sector analysis is made by compiling a regional (regional as geographically opposed to national, not to be mistaken for the Belgian Regions Brussels, Flanders and Wallonia) input-output table, resorting to microeconomic data: a bottom-up approach. The main customers and suppliers of the port's key players or stakeholders are identified. A geographical analysis can also be carried out by using data at a disaggregate level. Each customer or supplier can be located by means of their postcode. In so doing, the economic impact of the port is quantified, both functionally and geographically. In the case of the port of Antwerp, the results show important links between freight forwarders and agents. The geographical analysis suggests the existence of major agglomerating effects in and around the port of Antwerp, referred to as a major transhipment location point. Key words: port economics, regional input-output table, sector analysis, geographical analysis.port economics, regional input-output table, sector analysis, geographical analysis

Billiards in a general domain with random reflections

We study stochastic billiards on general tables: a particle moves according to its constant velocity inside some domain ${\mathcal D} \subset {\mathbb R}^d$ until it hits the boundary and bounces randomly inside according to some reflection law. We assume that the boundary of the domain is locally Lipschitz and almost everywhere continuously differentiable. The angle of the outgoing velocity with the inner normal vector has a specified, absolutely continuous density. We construct the discrete time and the continuous time processes recording the sequence of hitting points on the boundary and the pair location/velocity. We mainly focus on the case of bounded domains. Then, we prove exponential ergodicity of these two Markov processes, we study their invariant distribution and their normal (Gaussian) fluctuations. Of particular interest is the case of the cosine reflection law: the stationary distributions for the two processes are uniform in this case, the discrete time chain is reversible though the continuous time process is quasi-reversible. Also in this case, we give a natural construction of a chord "picked at random" in ${\mathcal D}$, and we study the angle of intersection of the process with a $(d-1)$-dimensional manifold contained in ${\mathcal D}$.Comment: 50 pages, 10 figures; To appear in: Archive for Rational Mechanics and Analysis; corrected Theorem 2.8 (induced chords in nonconvex subdomains

Optimization of mesoporous titanosilicate catalysts for cyclohexene epoxidation via statistically guided synthesis

An efficient approach to improve the catalytic activity of titanosilicates is introduced. The Doehlert matrix (DM) statistical model was utilized to probe the synthetic parameters of mesoporous titanosilicate microspheres (MTSM), in order to increase their catalytic activity with a minimal number of experiments. Synthesis optimization was carried out by varying two parameters simultaneously: homogenizing temperature and surfactant weight. Thirteen different MTSM samples were synthesized in two sequential ‘matrices’ according to Doehlert conditions and were used to catalyse the epoxidation of cyclohexene with 'tert'-butyl hydroperoxide. The samples (and the corresponding synthesis conditions) with superior catalytic activity in terms of product yield and selectivity were identified. In addition, this approach revealed the limiting values of each synthesis parameter, beyond which the material becomes catalytically ineffective. This study demonstrates that the DM approach can be broadly used as a powerful and time-efficient tool for investigating the optimal synthesis conditions of heterogeneous catalysts

Effects of zeolite particle size and internal grain boundaries on Pt/Beta catalyzed isomerization of n-pentane

The impact of particle size and internal grain boundaries of Beta zeolites was investigated in n-pentane isomerization over bifunctional Pt/Beta catalysts, by comparing the catalytic performance of four as-synthesized Pt/Beta samples that possess an identical Pt loading (0.5 wt%), but use four distinct Beta zeolites. Three of them contain polycrystalline zeolites, consisting of nano-sized crystals with a similar size of 9–13 nm, but having different average particle sizes (i.e., 1340, 830, and 250 nm) and numerous internal grain boundaries, as found via high-resolution transmission electron microscopy. The last catalyst contains single-crystalline zeolite, with an average particle size of 225 nm, and no observed internal grain boundaries. At low reaction temperature ( 614 K), a large particle size and the presence of internal grain boundaries significantly reduce the apparent activity, because of the extended diffusion path and additional diffusion barriers, which are probably caused by a mismatch in micropore alignment and gas-zeolite interfaces at these grain boundaries. Due to the small particle size and absence of internal grain boundaries, the observed activity for single-crystalline Beta can be 60–212% higher than for polycrystalline counterparts, even though it possesses a much weaker intrinsic acidity. This shows, remarkably, that single-crystalline zeolites with less internal grain boundaries can achieve a much higher catalytic activity

Steady-State Properties of Single-File Systems with Conversion

We have used Monte-Carlo methods and analytical techniques to investigate the influence of the characteristic parameters, such as pipe length, diffusion, adsorption, desorption and reaction rate constants on the steady-state properties of Single-File Systems with a reaction. We looked at cases when all the sites are reactive and when only some of them are reactive. Comparisons between Mean-Field predictions and Monte-Carlo simulations for the occupancy profiles and reactivity are made. Substantial differences between Mean-Field and the simulations are found when rates of diffusion are high. Mean-Field results only include Single-File behavior by changing the diffusion rate constant, but it effectively allows passing of particles. Reactivity converges to a limit value if more reactive sites are added: sites in the middle of the system have little or no effect on the kinetics. Occupancy profiles show approximately exponential behavior from the ends to the middle of the system.Comment: 15 pages, 20 figure