Migration, nostalgia and the building of a food imaginary: Mexican migrants at "La Pulga" market in San Joaquin Valley, California

In the context of transnational migration, ethnic markets function as segmented spaces where migrants as a group may be observed on many levels. Provisioning in the market (as much by immigrants as by natives or long-term residents) as well as the consumption of prepared food in situ compel a multiplicity of social interactions that facilitate knowledge and social relations, including recipes, memories, nostalgia, circulation of products and culinary techniques. In addition, a market can acquire a role as a meaningful transnational space of confluence for a system of relations and representations that help to decipher the complex social reality of subjects involved in a transnational migration phenomenon. With this paper we aim to highlight how a migratory context as well as the collectivization of a sensory experience as seen in an itinerant Mexican food market in California lead to the construction of a food imaginary related to Mexican food when it is disassociated from the original context in which it is produced. Thus, by means of an ethnographic approach, this paper aims to demonstrate how the collectivization of a sensory experience, framed under culinary nostalgia and triggered by the performativity and reflexivity of the subjects that take part in market activity, enables the construction of a food imaginary for the Mexican migrants that are regular clients of an itinerant market in California. (author's abstract

Capillary rise of a liquid between two vertical plates making a small angle.

The penetration of a wetting liquid in the narrow gap between two vertical plates making a small angle is analyzed in the framework of the lubrication approximation. At the beginning of the process, the liquid rises independently at different distances from the line of intersection of the plates except in a small region around this line where the effect of the gravity is negligible. The maximum height of the liquid initially increases as the cubic root of time and is attained at a point that reaches the line of intersection only after a certain time. At later times, the motion of the liquid is confined to a thin layer around the line of intersection whose height increases as the cubic root of time and whose thickness decreases as the inverse of the cubic root of time. The evolution of the liquid surface is computed numerically and compared with the results of a simple experiment

Unveiling shocks in planetary nebulae

The propagation of a shock wave into a medium is expected to heat the material beyond the shock, producing noticeable effects in intensity line ratios such as [O III]/Halpha. To investigate the occurrence of shocks in planetary nebulae (PNe), we have used all narrowband [O III] and Halpha images of PNe available in the HST archive to build their [O III]/Halpha ratio maps and to search for regions where this ratio is enhanced. Regions with enhanced [O III]/Halpha emission ratio can be ascribed to two different types of morphological structures: bow-shock structures produced by fast collimated outflows and thin skins enveloping expanding nebular shells. Both collimated outflows and expanding shells are therefore confirmed to generate shocks in PNe. We also find regions with depressed values of the [O III]/Halpha ratio which are found mostly around density bounded PNe, where the local contribution of [N II] emission into the F656N Halpha filter cannot be neglected.Comment: 13 pages, 9 figures, 3 tables; To appear in Astronomy & Astrophysic

Stripe to spot transition in a plant root hair initiation model

A generalised Schnakenberg reaction-diffusion system with source and loss terms and a spatially dependent coefficient of the nonlinear term is studied both numerically and analytically in two spatial dimensions. The system has been proposed as a model of hair initiation in the epidermal cells of plant roots. Specifically the model captures the kinetics of a small G-protein ROP, which can occur in active and inactive forms, and whose activation is believed to be mediated by a gradient of the plant hormone auxin. Here the model is made more realistic with the inclusion of a transverse co-ordinate. Localised stripe-like solutions of active ROP occur for high enough total auxin concentration and lie on a complex bifurcation diagram of single and multi-pulse solutions. Transverse stability computations, confirmed by numerical simulation show that, apart from a boundary stripe, these 1D solutions typically undergo a transverse instability into spots. The spots so formed typically drift and undergo secondary instabilities such as spot replication. A novel 2D numerical continuation analysis is performed that shows the various stable hybrid spot-like states can coexist. The parameter values studied lead to a natural singularly perturbed, so-called semi-strong interaction regime. This scaling enables an analytical explanation of the initial instability, by describing the dispersion relation of a certain non-local eigenvalue problem. The analytical results are found to agree favourably with the numerics. Possible biological implications of the results are discussed.Comment: 28 pages, 44 figure

Is emamectin benzoate effective against the different stages of Spodoptera exigua (Hübner) (Lepidoptera, Noctuidae)?

peer-reviewedThis work was partially supported by the Spanish Ministry of Science and Innovation (project AGL 2007-66130-C03-02 to P. Medina). F. Amor and P. Bengochea acknowledge the ministry of Education and Culture and the Technical University of Madrid (UPM) for the doctoral fellowships. Special thanks to Syngenta Agro S.A. for their support.The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera, Noctuidae), is a major polyphagous pest in greenhouses and open fields worldwide and also a main problem in sweet pepper greenhouses. The effectiveness of the pesticide emamectin benzoate was tested in the laboratory on different stages of S. exigua using different concentrations and uptake routes. After dipping young (48-h-old) S. exigua eggs in emamectin benzoate at 0.5, 1 and 1.5 mg/L a.i. the chemical did not exhibit any ovicidal activity. There was, however, progressive neonate mortality at all concentrations, culminating at 72 hours after hatching, when 100% of the larvae from the treated young eggs died. Second and fourth instar S. exigua larvae did not exhibit significant mortality when exposed to the inert surfaces which were treated. In contrast, ingesting a diet contaminated with 0.5 mg/L a.i. of emamectin benzoate caused 100% mortality in L2 and L4 larvae 24 and 72 hours after ingestion, respectively. The LC50 value of the compound against L4 larvae that fed on sprayed sweet pepper leaves for 24 hours was 0.81 mg/L a.i.. When adults were fed on a solution of 0.5 mg/L a.i., there was a reduction in the female and male lifespan of 29.3% and 55.3%, respectively. Fecundity was reduced by more than 99%. These data suggest that emamectin benzoate is not only a useful insecticide when ingested by beet armyworm larvae but it also has ovolarvicidal and adult activity.Spanish Ministry of Science and Innovatio

Efeito da irrigação no crescimento de plantas de seringueira em viveiro.

Durante tres anos (1981-1983) foi conduzido, em viveiro, na Estacao Experimental do CNPSD, em Manaus-AM, um estudo objetivando avaliar os efeitos da irrigacao e da interacao irrigacao x fertilizantes sobre a altura e diametro de caule da seringueira (Hevea spp.). O delineamento experimental utilizado foi o de blocos ao acaso em esquema fatorial, contendo os seguintes tratamentos: irrigado/adubado (IA), irrigado/nao adubado (INA), nao irrigado/adubado (NIA) e nao irrigado/nao adubado (NINA). Nos tratamentos irrigados, o solo foi abastecido ate a capacidade de campo, a profundidade de 25 cm, toda vez que o potencial matricial por metro atingia -0,5 bar, ao passo que, nos adubados, uma mistura de NPKMg foi parcelada em cinco aplicacoes a cada 30 dias, sendo a primeira efetuada aos 60 dias apos o plantio. Nos dois primeiros anos analisados, verificou-se que os tratamentos irrigados foram significativamente superiores aos nao irrigados, particularmente quando a irrigacao esteve associada a adubacao. Em geral, o comportamenteo das diferentes praticas testadas apresentaram a seguinte ordem decrescente: IA>INA>NIA>NINA. Nao foi observada interacao dos efeitos principais (irrigacao x adubacao)

Magnetic force microscopy investigation of arrays of nickel nanowires and nanotubes

The magnetic properties of arrays of nanowires (NWs) and nanotubes (NTs), 150 nm in diameter, electrodeposited inside nanoporous polycarbonate membranes are investigated. The comparison of the nanoscopic magnetic force microscopy (MFM) imaging and the macroscopic behavior as measured by alternating gradient force magnetometry (AGFM) is made. It is shown that MFM is a complementary technique that provides an understanding of the magnetization reversal characteristics at the microscopic scale of individual nanostructures. The local hysteresis loops have been extracted by MFM measurements. The influence of the shape of such elongated nanostructures on the dipolar coupling and consequently on the squareness of the hysteresis curves is demonstrated. It is shown that the nanowires exhibit stronger magnetic interactions than nanotubes. The non-uniformity of the magnetization states is also revealed by combining the MFM and AGFM measurements.Comment: 7 pages, 5 figure