Fluctuations and Pattern Formation in Fluids with Competing Interactions

One of the most interesting phenomena in the soft-matter realm consists in the spontaneous formation of super-molecular structures (microphases) in condition of thermodynamic equilibrium. A simple mechanism responsible for this self-organization or pattern formation is based on the competition between attractive and repulsive forces with different length scales in the microscopic potential, typically, a short-range attraction against a longer-range repulsion. We analyse this problem by simulations in 2D fluids. We find that, as the temperature is lowered, liquid-vapor phase separation is inhibited by the competition between attraction and repulsion, and replaced by a transition to non-homogeneous phases. The structure of the fluid shows well defined signatures of the presence of both intra- and inter-cluster correlations. Even when the competition between attraction and repulsion is not so strong as to cause microphase formation, it still induces large density fluctuations in a wide region of the temperature-density plane. In this large-fluctuation regime, pattern formation can be triggered by a weak external modulating field.Comment: To appear in the proceedings of the "International workshop on collective phenomena in macroscopic systems", 2006 Villa Olmo (Como), Ital

The impact of network formation on technology use among female headed households in rural Southern Philippines

This study was undertaken to investigate the farming activities of female headed households in the Philippines. In particular. how resource-poor households utilize networks to access resources and technology;To accomplish the above purpose, a survey questionnaire was prepared in the Department of Sociology in Iowa State University. After approval. it was translated and taken to the sampled 8 rural barrios which had previously been stratified according to population and migration status. All female heads of households in these barrios were interviewed by females who were residents of the barrios;Results indicate that FHHs\u27 and households\u27 characteristics are important factors in accessing resources and technology. Among these characteristics are parental land status, origin, age, education and marital status of FHHs, household size and male:female ratio. Specifically, young FHHs had many laborers even if they did not join rotational work groups. FHHs with high educational attainment who joined agricultural related associations had high income. With the husband present, households had high income and consumed more harvested produce. Larger households had higher income when the FHHs joined many associations or when they joined rotational work groups;The advantage in joining agricultural related associations was qualified by the positive relationship with animals raised, value of harvest consumed and higher income. Likewise, joining few associations was related to more draft animals owned and the use of indigenous technology;Rotation work groups complemented the use of indigenous technology which was associated with larger household size that promoted the cultivation of more land. Similar to indigenous technology, attendance in training had a positive effect on cultivated area. Training benefit was also enhanced if this was conducted in small groups. On the other hand, extension visit was dysfunctional in that households that were not visited had higher income and consumed more harvested produce;On the basis of the results, two middle ranged theories are proposed. These are the theory of social loss and the religious connectivity theory

Force calculation on walls and embedded particles in multiparticle collision dynamics simulations

Colloidal solutions posses a wide range of time and length scales, so that it is unfeasible to keep track of all of them within a single simulation. As a consequence some form of coarse-graining must be applied. In this work we use the Multi-Particle Collision Dynamics scheme. We describe a particular implementation of no-slip boundary conditions upon a solid surface, capable of providing correct force s on the solid bypassing the calculation of the velocity profile or the stre ss tensor in the fluid near the surface. As an application we measure the friction on a spherical particle, when it is placed in a bulk fluid and when it is confined in a slit. We show that the implementation of the no-slip boundary conditions leads to an enhanced Ensko g friction, which can be understood analytically. Because of the long-range nature of hydrodynamic interactions, the Stokes friction obtained from the simulations is sensitive of the simulation box size. We address this topic for the slit geometry, showing that that the dependence on the system size differs very much from what is expected in a 3D system, where periodic boundary conditions are used in all directions.Comment: To appear in Physical Review

Detection of IncP replicon-specific regions in DNA from Antarctic microbiota

Abstract Plasmids capable of horizontal transfer contribute to the adaptability of bacteria, as they may provide genes that enable their hosts to cope with different selective pressures. Only limited information is available on plasmids from Antarctic habitats, and up until now surveys have only used traditional methods of endogenous plasmid isolation. The method based on primer systems, designed on the basis of published sequences for plasmids from different incompatibility (Inc) groups, is appropriate to detect the replicon-specific regions of corresponding plasmids in cultured bacteria, or in total community DNA, which share sufficient DNA similarity with reference plasmids at the amplified regions. In this study, we applied broad-host-range plasmid-specific primers to DNA from microbial samples collected at six different locations in Northern Victoria Land (Antarctica). DNA preparations were used as targets for PCR (polymerase chain reaction) amplification with primers for the IncP (trfA2) and IncQ (oriV ) groups. PCR products were Southern blotted and hybridized with PCR-derived probes for trfA2 and oriV regions. This approach detected the occurrence of IncP-specific sequences in eight out of fifteen DNA samples, suggesting a gene-mobilizing capacity within the original habitats

Effects of environmental variability and offspring growth on the movement ecology of breeding Scopoli's shearwater Calonectris diomedea

Abstract Most seabird species display colonial behavior during the breeding period which implies that food resources around breeding sites can easily go depleted. Seabirds need to both reach profitable areas, which can be located far from the colony, and return to the colony regularly. In this context, flexibility in movement behavior may be crucial for breeding success. During chick-rearing, Procellariformes species can alternate short trips lasting 1–4 days for chick provisioning with longer trips for self-provisioning in what has been called a dual-foraging strategy. We analyzed foraging trips from 136 Scopoli's shearwaters from three Mediterranean colonies tracked with GPS during 6 chick-rearing seasons to assess whether the adoption of a dual foraging strategy depends on the quality of habitat surrounding the colony. We found a marked dual-foraging strategy only in birds from the Linosa colony which was the largest colony in terms of breeding pairs and was characterized by having a lower marine habitat quality. Birds from this colony performed foraging trips that extended up to 369 km from the nest and lasted more than 10 days. In general, the decision to perform long lasting trips was triggered by lower values of primary production and higher offspring weight. Contrary to expectation, the decision to feed far from the colony was not related to the parents' weight. At the same time, despite the higher productivity offered by distant areas, the higher proportion of long trips performed by birds breeding in poor areas was not sufficient to maintain the same body mass as the ones breeding in richer areas

Educare a pensare criticamente nella scuola primaria: risultati preliminari da uno studio empirico

This paper describes the epistemological, theoretical, and methodologicalframework of an empirical study on the development of critical thinkingskills for primary school students. Critical thinking has been recognizedworldwide as a key competence to enable active citizenship. The current researchdesign comprises a two-year intervention in 12 experimental and controlclasses (grades 2-3 and 4-5) in the Friuli Venezia Giulia region. Teachersnominated their classes to take part in the project through a region-widesurvey aimed at investigating the most implemented teaching approaches.After a teacher training on one of the existing frameworks to promote thinking(TASC - Thinking Actively in a Social Context, by B. Wallace), the teachersare implementing the approach in their classes with the continuing supportof the researcher. A tool specifically developed was employed as an initialand mid-term assessment to appraise students’ performances, in terms ofcritical thinking dialogue and dispositions. The final assessment will takeplace in April 2020. The current paper will address and discuss the researchdesign and the preliminary results of the study.Questo articolo descrive il quadro epistemologico, teorico e metodologicodi uno studio empirico sullo sviluppo della capacità di pensiero critico neglistudenti delle scuole elementari. Il pensiero critico è stato riconosciuto intutto il mondo come una competenza chiave per l’esercizio della cittadinanzaattiva. Il disegno di questa ricerca prevede un intervento biennale in12 classi sperimentali e di controllo (classi II-III e IV-V) nella regione FriuliVenezia Giulia. Gli insegnanti hanno candidato le loro classi a prendere parteal progetto attraverso un questionario a livello regionale, volto a studiare gliapprocci didattici più implementati. Dopo una formazione docenti su unodei framework di apprendimento esistenti per la promozione del pensiero(TASC - Thinking Actively in a Social Context, di B. Wallace), gli insegnantistanno utilizzando l’approccio nelle loro classi con il continuo supporto delricercatore. Una prova appositamente costruita è stata utilizzata come valutazioneiniziale e intermedia delle performance degli studenti, in termini didialogo e disposizioni sul pensiero critico. La valutazione finale avrà luogoin aprile 2020. Il presente articolo affronterà e discuterà del disegno della ricercae dei risultati preliminari dello studio

Il ruolo geopolitico ed economico dei viceconsoli di Terra d'Otranto (1816-1860)

The development of commercial relations between the Kingdom of the Two Sicilies and foreign nations – which occurred during the period among the Bourbon restoration to the unification of Italy and which was characterized by the stipulation of various commercial treaties between the various states – determined a constant increase in vice-consulates also in Terra d'Otranto, aimed at protecting the interests of foreign citizens and promoting the development of trade. The essay aims to highlight not only the functions but also the geopolitical and economic role of the viceconsuls in Terra d'Otranto in the aforementioned historical period. Particular attention is paid to some real consular decrees, to the appointment procedure and to the reconstruction of the names lists of these officials