Search Results - (Author, Cooperation:Bustamante)

Garcia-Rodeja Gayoso; Isabel; de Bustamante, Joaquín Diaz; Harms, Ute

Unknown

403 S.

8481219649

2019-08-22

This article is intended to carry out a comparative exercise of the creation of values and production costs by taking as an object the crop of lettuce in a conventional peasant production and in an agro-ecological production. From there, a part of the theory of labor value, based on Marx's ideas is put into discussion to try to show in which of the two types of crops, the work, measured in time, is greater. Based on this, an analysis of the real production costs is made and it is a matter of contributing to the discussion of the tendency of gentrification of the agro-ecological products. Two central categories are worked: food empires and agro-industrial system and, with the concept of imperialism being a part of both of them in order to understand the relation that agro-ecology has about the baseline laws of current social relations of production.

Este artículo tiene por objeto, realizar un ejercicio comparativo de la creación de valores y los costos de producción, tomando como objeto el cultivo de lechuga en una producción campesina convencional y otra agroecológica. A partir de allí, se pone en discusión una parte de la teoría del valor-trabajo fundamentada por Marx para tratar de evidenciar en cuál de los dos tipos de cultivo el trabajo, medido en tiempo, es mayor. Con base en ello, se hace un análisis de los reales costos de producción y se trata de aportar a la discusión de la tendencia a la elitización de los productos agroecológicos.

Soziologie, Anthropologie ; Sociology & anthropology ; agro-ecological production; conventional production; theory of labor value; productive labor and capitalism ; Agrarsoziologie ; Wirtschaftssoziologie ; Rural Sociology ; Sociology of Economics

Zeitschriftenartikel, journal article

2021-08-11

This study aimed to compare the gap between gender role values and domestic practice in the UK and Spain. The data were drawn from a sample of British and Spanish male and female respondents to the International Social Survey Programme’s (ISSP) ‘Family and Changing Gender Roles’ module (2002, 2012) and used to create multivariate mod­els using ordinary least-squares regression techniques. The findings suggest that gender role values impacts domestic practice: more time is devoted to housework by egalitar­ian than non-egalitarian men and less by egalitarian than non-egalitarian women. That effect was not observed for care-giving, however. The impact of gender values on the division by sex of household chores was found to be similar in the UK and Spain. A gradual move to more egalitarian ideals was also observed in both countries over the 10 year period studied.

Sociology & anthropology ; Social sciences, sociology, anthropology ; Sozialwissenschaften, Soziologie ; Soziologie, Anthropologie ; ZA3880 v1.1.0: International Social Survey Programme: Family and Changing Gender Roles III - ISSP 2002; ZA5900 v4.0.0: International Social Survey Programme: Family and Changing Gender Roles IV - ISSP 2012 ; Family Sociology, Sociology of Sexual Behavior ; Women's Studies, Feminist Studies, Gender Studies ; Frauen- und Geschlechterforschung ; Familiensoziologie, Sexualsoziologie ; gender relations ; caregiving ; ISSP ; gender role ; housework ; comparison ; Great Britain ; Spain ; Pflege ; Hausarbeit ; Spanien ; Großbritannien ; Geschlechtsrolle ; Geschlechterverhältnis ; Vergleich

journal article, Zeitschriftenartikel

2018-07-27

The article deals with the prerequisites and establishment of the first Russia-Mexico contacts, which took place after the Crimean War (1853-1856). It was revealed that Mexico’s interest in the collaboration with Russia began to reveal in a higher degree after the Crimean War. The factors, which had led to the diplomatic rapprochement of the two states, include the Mexico’s search for allies in the contradiction to increased aggression of European states and the USA in the Central American region, and the increase of Russian intellectuals’ emigration, resettlement of religious groups of the Old Russian sectarians to the region. At the turn of 19th – 20th centuries many Russian travelers and writers, such as S.D. Protopopov and K.D. Balmont, visited Mexico for the purpose of studying the culture of ancients Indians, who lived in Central America during many centuries before the Spanish colonization. Besides of the impressions on ancient Indian culture, these travelers described the life of ordinary Mexican people of that time. They mentioned their poverty and hopelessness in the years of Porfirio Dias’s dictatorship. Nevertheless, political and cultural contacts had begun to established in the late 19th century between the Russian Empire and Mexico, because after the Crimean War the Mexico’s interest to Russians increased. In addition, Russia tried to strengthen its position in Central American region. In total, these factors had led to the strengthening of political, social and cultural contacts between Russia and Mexico.

Internationale Beziehungen ; International relations ; Russia-Mexico relations; Crimean War; Benito Juárez; Porfirio Dias’s dictatorship; Russian emigration; Molokans ; International Relations, International Politics, Foreign Affairs, Development Policy ; internationale Beziehungen, Entwicklungspolitik ; 10500

journal article, Zeitschriftenartikel

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The superposition principle states that the angle-dependent difference in scattering intensities for right and left circularly polarized light, for chiral structures composed of various hierarchical levels, is the sum of the contributions from each level taken separately. Analytic expressions describing this superposition are obtained for oriented and rotationally averaged hierarchical chiral structures. It is shown that the superposition principle holds only when the coiling levels in the chiral structure are disparate. In particular, for a structure composed of two chiral levels, the lower order structure must be much smaller than both the wavelength of light and the higher order structure. Numerical calculations using these expressions are carried out for superhelices of varying dimensions.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

The applications of the scanning tunneling microscope (STM) in air are usually restricted to good conducting materials as clean metals, doped and passivated semiconductors, or to some molecular adsorbates deposited onto graphite. In order to study poor conducting materials as biological molecules, we have built a very low current STM. This instrument can routinely be operated at 0.1 pA while having a bandwidth of 7 kHz. The advantages of using very low currents are illustrated by imaging 5-nm-thick purple membranes. These membranes can only be imaged at currents smaller than 2 pA. © 1995 American Institute of Physics.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The main purpose of this study was to characterize the initial neurotransmission cascade elicited by methamphetamine, analysing simultaneously with in vivo microdialysis monoamine, amino acid and neuropeptide release in substantia nigra and neostriatum of the rat. The main effect of a single systemic dose of methamphetamine (15 mg/kg, subcutaneously) was an increase in dopamine levels, both in substantia nigra (≈ 10-fold) and neostriatum (≈ 40-fold), accompanied by a significant, but lesser, increase in dynorphin B (≈ two-fold, in both regions), and a decrease in monoamine metabolites. A similar effect was also observed after local administration of methamphetamine (100 µm) via the microdialysis probes, but restricted to the treated region. In other experiments, rats were repeatedly treated with methamphetamine or saline, with the last dose administered 12 h before microdialysis. Dopamine K+-stimulated release was decreased following repeated methamphetamine administration compared with that following saline, both in the substantia nigra (by ≈ 65%) and neostriatum (by ≈ 20%). In contrast, the effect of K+-depolarization on glutamate, aspartate and GABA levels was increased following repeated administration of methamphetamine. In conclusion, apart from an impairment of monoamine neurotransmission, repeated methamphetamine produces changes in amino acid homeostasis, probably leading to NMDA-receptor overstimulation.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

This paper presents the results of an experiment dealing with the absorption of electromagnetic waves in a longitudinally magnetized plasma waveguide at electron cyclotron frequency. Our results demonstrate, under different operating conditions, the importance of the polarization of the incident waves as well as the linear behavior of the plasma density as a function of the absorbed power. The gas used in this study was argon.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A polarization modulation microscope designed to detect and spatially resolve the distribution of optically anisotropic domains in microscopic objects is described. An image dissector camera is used as the detection device. The polarization of the light is modulated by means of a photoelastic modulator and a synchronous demodulation amplifier (lock-in) is utilized to obtain the difference image between the images formed using two orthogonal forms of the incident polarization on the sample. Preliminary results are described for the linear dichroism imaging measurements of polymerized hemoglobin (HbS) in red blood sickle cells. The present limitations of this design are discussed along with various strategies to improve its performance.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

Based on the confocal scanning and differential polarization imaging technique, a computer-controlled confocal scanning differential polarization microscope has been built. This system possesses extensive image processing capability that provides digitized regular and/or differential polarization images. This microscope combines the advantages of the confocal design and the extended electronic sensitivity of polarization modulated instrumentation to achieve the measurement of an anisotropy ratio as small as 10−5. In this paper, the basic theory and the instrument are described. In addition, some samples are used to test the actual performance of the system, and it is found that the system provides high resolution (0.3 μm at wavelength 546 nm), reduced depth of field, and high signal-to-noise ratio (83 dB at 10-ms integration time) images. Finally, some biological applications are shown.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A differential polarization microscope forms two images: one of the transmitted intensity and the other due to the change in intensity between images formed when different polarizations of light are used. The interpretation of these images for linear dichroism and circular dichroism are described. The design constraints on the data acquisition systems and the polarization modulation are described. The advantage of imaging several biological systems which contain optically anisotropic structures are described.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

The Advanced Light Source (ALS) is a synchrotron radiation facility based on a low-emittance, 1.5-GeV electron storage ring presently under construction at the Lawrence Berkeley Laboratory, U.S.A. Plans are under way to develop a polarized photon facility at the ALS, exploiting the natural polarization properties of the bend magnet synchrotron radiation. The radiation emitted in the plane of the storage ring is linearly polarized, while above and below the plane it is elliptically polarized. We will utilize these properties to obtain circularly polarized soft x rays. A participating research team (PRT A018) has been formed and is proceeding with the design of a high-resolution beamline in the soft x-ray energy region 100–1500 eV. Intense beams of monochromatic, tunable, pulsed, circularly polarized photons will become available. We will discuss the physical characteristics of this polarized soft x-ray source. New investigations in biology, materials science, physics, and chemistry will become accessible. Initial experiments using circularly polarized photons in the soft x-ray region are planned in the areas of differential scattering and absorption from chiral molecules and probing the electronic and magnetic properties of magnetic systems. This work was supported by the U.S. Department of Energy (DE-AC03-76SF00098).

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The identification of mononuclear cells extracted from cutaneous tumours (basal cell carcinoma, squamous cell carcinoma and superficial spreading melanoma) has been investigated. The relative numbers of T cells and B cells have been determined using the E-rosette test and the EAC-rosette test. The results have been compared to those of delayed hypersensitivity type reactions. Different cell distribution patterns (E/EAC ratio) have been found in the infiltrates according to the type of tumour.An immunocytochemical technique has been developed for the identification in situ of immunoglobulin-producing cells in the inflammatory infiltrates. In each case the class of immunoglobulin (IgM, IgG or IgA) has been identified and the relative frequency of Ig-producing cells has been determined.The results indicate humoral and cellular immune responses with variations attributable to the type of tumour. In weakly malignant tumours, the infiltrate is characterized by an elevated number of T lymphocytes and numerous plasma cells which secrete all classes of Ig; in highly malignant tumours it is characterized by a reduced number of both T lymphocytes (E rosette) and plasma cells which do not secrete all classes of Ig.

Electronic Resource

1365-4632

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1745-4557

Blackwell Publishing Journal Backfiles 1879-2005

Process Engineering, Biotechnology, Nutrition Technology

Mango fruit has a relatively short storage life of about 2 to 3 weeks at 13C. In order to prolong the storage life of ‘Haden’ mangoes, fruit were coated with 3 concentrations (8,16 and 24 g.L−1) of the edible coating film “Semperfresh” and then stored at 13C and 85% RH. Fruit were then evaluated every 4 days for up to 32 days for total soluble solids (TSS), titratable acidity (TA), pH, firmness, weight loss, color of the skin, and ascorbic acid content. All 3 concentrations applied to the fruit affected fruit ripening. TA, firmness, and green color were higher in coated fruit, and weight loss, SST, and pH were lower compared with the noncoated fruit. “Semperfresh” had no effect on decay development. Ascorbic acid decreased in all stored fruit, but this decrease was slower in coated fruit, and there were no significant differences between the different “Semperfresh” concentrations.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

A theory of the polymer and salt induced (psi)-type circular dichroism observed in DNA aggregates is presented. Using the main formalism developed in the previous paper to treat the interaction of light and large, dense molecular aggregates, it is shown that the anomalously large signals observed in the circular dichroism of certain molecular aggregates result from: (a) the presence of a long-range chiral structure in the aggregate; (b) delocalization throughout the entire particle of the light-induced excitations in the chromophores. This delocalization and the resulting "collective response'' of the chromophores in the aggregate is favored in particles having a three-dimensional packing. It is shown that to describe adequately the internal field in these aggregates, intermediate and radiation coupling mechanisms should be taken into account in addition to the regular dipole–dipole interactions. Furthermore, no dipole approximation in the exponentials of the form eik⋅x are made. It is shown that in these circumstances, one of the circular polarizations of the light can exchange energy more efficiently than the opposite polarization. This gives rise to a circular dichroism signal whose magnitude is proportional to the overall size and long-range chiral nature of the aggregates. The theory is applied to two cases: (1) to the dimer ApA when it is shown (for the case of this small system) to reduce to the classical theories of DeVoe and Tinoco, and (2) for a toroidal aggregate of DNA of 3000 A(ring) diameter with an internal chiral structure, as found by Haynes et al. in polylysine–DNA condensates. Good qualitative agreement with the observed spectra is found. The theory represents the first successful attempt to explain the physical origin of the psi-type CD effect. Useful information regarding the chiral structure of the aggregates can be inferred from the theory.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

A general method to describe the spectroscopy of large, internally inhomogeneous particles is presented. The theory utilizes an approach similar to the one used by DeVoe in the treatment of the optical properties of polymers. The particle is divided into groups and the internal field is calculated by solving a self-consistent set of linear equations in the field amplitude at each group in the particle. It is found that if the particle is dense the intermediate and radiation coupling mechanisms must be included in addition to the dipole–dipole coupling. Through these coupling mechanisms it is found that the excitation generated at each group in the chromophore can delocalize over regions comparable to the size of the wavelength of light. The response of the particle to the light can then be described in terms of "collective modes'' of excitation of the entire particle, the amplitude of each mode being controlled by the geometrical relation between the groups and the efficiency in energy transfer between any two groups in the aggregate. The spatially averaged equations of the absorbance for a collection of large inhomogeneous arbitrarily shaped aggregates are derived.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Computations have been carried out to determine how the magnitude and shape of the polymer and salt induced (psi)-type CD spectra depend on the structural properties of a collection of randomly oriented large chiral aggregates. Uniaxial polarizable groups located at the cubic lattice points have been used to model the aggregates. The structure of the model is similar to that of a cholesteric liquid crystal. All computations have been carried out for the case of polarizable groups possessing only one electronic transition between 200 and 320 nm. It is found that the radiation and intermediate couplings between the chromophores in the aggregate which are neglected in previous theories play an important role in determining the shape and magnitude of the psi-type CD spectrum. It is shown that when these couplings are included, only three-dimensional large chiral aggregates show huge and nonconservative psi-type CD spectra. It is shown that the magnitude of the psi-type CD spectrum is controlled by the volume, the chromophore density, and the pitch of the aggregate, while the shape of the psi-type CD spectrum is determined mostly by the pitch and the handedness of an aggregate. When the pitch is close to the center of the absorption band of the chromophore in the aggregate the most distorted (least conservative) psi-type CD spectrum is obtained. The CD spectra of aggregates with opposite handedness are mirror images of each other. It is shown that a rotationally disordered collection of chiral aggregates cannot give rise to a selective reflection of one circular polarization over the other as shown by liquid crystals. The results obtained confirm the theoretical predictions of the two previous papers in this series.

Electronic Resource