7,146 research outputs found
El campesinado de la Amazonia colombiana: una historia de menosprecio institucional, constitución identitaria y lucha por el reconocimiento
To understand the construction processes of the identity and organizational experiences of the peasants who currently inhabit the Colombian western Amazon region, it is necessary to know the historical characteristics that defi ned the social occupation of this geographical area. As in other colonization processes which took place in the Peruvian, Bolivian and Ecuadorian Amazon, in Colombia the peasants who occupied the Amazonian space in the fifties and sixty arrived after being expelled by the reproduction and expansion of the capital. But, unlike these countries, in Colombia, during these same years, the State undertook a military persecution against those peasants who had resisted the land expropriation process. In this sense, and seeking to comprehend the identity construction process of these peasants, this article will present a brief historical reconstruction of their first organizational efforts and a description of how they undertook their identification process as a social group. Finally, the article will analyze the mechanisms of resistance that Colombian Amazon peasants have created and consolidated in their struggles for recognition and their struggles against injustice and institutional disrespect experienced by decades.Para comprender los procesos de construcción identitarios y organizacionales de los campesinos que habitan actualmente en la Amazonia occidental colombiana es necesario conocer las particularidades históricas que defi nieron la ocupación social de este espacio geográfico. Al igual que en otros procesos de colonización ocurridos en la Amazonia peruana, boliviana o ecuatoriana, en Colombia los campesinos que ocuparon el espacio amazónico en los años cincuenta y sesenta llegaron después de ser expulsados por las dinámicas de reproducción y ampliación del capital. Ahora bien, a diferencia de estos países, en Colombia el Estado emprendió durante esos años, de manera concomitante, una
dura persecución militar contra los campesinos que se habían resistido a la expropiación de sus territorios. En este sentido y para acercarnos a una comprensión de los procesos de constitución de las identidades de estos campesinos, en este artículo se presentará una breve reconstrucción histórica de sus primeros esfuerzos organizativos y la manera como emprendieron sus procesos de identificación como grupo. Finalmente, analizaremos los mecanismos de resistencia que los campesinos han ido creando y consolidando en sus luchas por el reconocimiento y contra la injusticia y el menosprecio institucional de que han sido objeto a lo largo de su historia.UFPA - Universidade Federal do Par
Neuroimmune Crosstalk: A Role for Neuropeptide Y in Inflammatory Bowel Disease
Neuropeptide Y (NPY) is a 36-amino acid peptide widely expressed in the central and peripheral nervous systems. In addition to other cells, NPY is also synthesized and co-released from sympathetic nerve fibers functioning as a potent sympathetic neuromodulator. NPY has been implicated in playing important roles in the regulation of energy balance, appetite, anxiety, vascular tone, and immune cell functioning. In addition, immune cells of both the innate and adaptive immune systems express functional NPY receptors. Some immune cells can produce and secrete NPY, and genetic alteration of these receptors results in altered immune cell functioning. Its direct association with the immune system, its presence in sympathetic neurons innervating primary and secondary immune organs and its close association with vasculature, make NPY a candidate for mediating, at least in part, the neuroimmune crosstalk. The gene expression results presented here suggest that DSS is a valid model of human IBD and that pain-related behavior in the open field is closely associated with DSS-induced gene changes. Furthermore, the data suggest that NPY signaling via its Y1 receptor plays some regulatory role in the immune process induced by DSS. Y2 receptor antagonism resulted in a mild attenuation of immune activity but also slightly attenuated pain-related behavior in the open field. In sum, it appears that NPY signaling via its Y1 and Y2 receptors plays a role in various features of DSS induced disease
Genetic Engineering to Enhance Mercury Phytoremediation
Most phytoremediation studies utilize merA or merB genes to modify plants via the nuclear or chloroplast genome, expressing organomercurial lyase and/or mercuric ion reductase in the cytoplasm, endoplasmic reticulum or within plastids. Several plant species including Arabidopsis, tobacco, poplar, rice, Eastern cottonwood, peanut, salt marsh grass and Chlorella have been transformed with these genes. Transgenic plants grew exceedingly well in soil contaminated with organic (~400 μM PMA) or inorganic mercury (~500 μM HgCl2), accumulating Hg in roots surpassing the concentration in soil (~2000 μg/g). However, none of these plants were tested in the field to demonstrate real potential of this approach. Availability of metal transporters, translocators, chelators and the ability to express membrane proteins could further enhance mercury phytoremediation capabilities
Innovation beyond Patents: Technological Complexity as a Protection against Imitation
A large portion of innovators do not patent their inventions. This is a relative puzzle since innovators are often perceived to be at the mercy of imitators in the absence of legal protection. In practice, innovators however invest actively in making their products technologically hard to reverse engineer. We consider the dynamics of imitation and investment in technological complexity, both by the innovator and by imitators. We show it can justify high level of proÖts beyond patents, can shed light on the regulation of reverse engineering and can explain delays in adoption of innovations
Characterization of Heterologous Multigene Operons in Transgenic Chloroplasts. Transcription, Processing, and Translation1
The first characterization of transcriptional, posttranscriptional, and translational processes of heterologous operons expressed via the tobacco (Nicotiana tabacum) chloroplast genome is reported here. Northern-blot analyses performed on chloroplast transgenic lines harboring seven different heterologous operons revealed that polycistronic mRNA was the predominant transcript produced. Despite the lack of processing of such polycistrons, large amounts of foreign protein accumulation was observed in these transgenic lines, indicating abundant translation of polycistrons. This is supported by polysome fractionation assays, which allowed detection of polycistronic RNA in lower fractions of the sucrose gradients. These results show that the chloroplast posttranscriptional machinery can indeed detect and translate multigenic sequences that are not of chloroplast origin. In contrast to native transcripts, processed and unprocessed heterologous polycistrons were stable, even in the absence of 3′ untranslated regions (UTRs). Unlike native 5′UTRs, heterologous secondary structures or 5′UTRs showed efficient translational enhancement independent of cellular control. Abundant read-through transcripts were observed in the presence of chloroplast 3′UTRs but they were efficiently processed at introns present within the native operon. Heterologous genes regulated by the psbA (the photosystem II polypeptide D1) promoter, 5′ and 3′UTRs have greater abundance of transcripts than the endogenous psbA gene because transgenes were integrated into the inverted repeat region. Addressing questions about polycistrons, and the sequences required for their processing and transcript stability, are essential in chloroplast metabolic engineering. Knowledge of such factors would enable engineering of foreign pathways independent of the chloroplast complex posttranscriptional regulatory machinery
Thinning of the Corpus Callosum and Cerebellar Atrophy is Correlated with Phenotypic Severity in a Family with Spastic Paraplegia Type 11
Background Mutations in the spatacsin gene are associated with spastic paraplegia type 11 (SPG11), which is the most-common cause of autosomal recessive hereditary spastic paraplegia. Although SPG11 has diverse phenotypes, thinning of the corpus callosum is an important feature.Case Report Clinical, genetic, and radiological evaluations were undertaken in a large family from Gujarat in North India with hereditary spastic paraplegia, whose affected members presented with varying degrees of spasticity, ataxia, and cognitive impairment. The clinical severity and the degree of corpus callosum and cerebellar atrophy varied among the four affected individuals in the family. Genetic testing of the affected members revealed recessive mutations in the spatacsin gene, consistent with a diagnosis of SPG11.Conclusions We believe that the extent of corpus callosum thinning and cerebellar atrophy is correlated with disease severity in affected patients. The addition of extrapyramidal features in the most-affected members suggests that SPG11 exhibits considerable phenotypic heterogeneity. J Clin Neurol 2011;7:102-10
Gobierno corporativo, diversificación estratégica y desempeño empresarial en México
We study the relationships among corporate governance, strategic diversification and financial performance in Mexico. The study uses data from 99 non-financial firms listed in the BMV (Mexican Stock Market) during 2004. The main findings are: Firms which property is concentrated in a principal shareholder focus on the domestic market. Family firms try to diversify their productive activities and sources of income. There are no trends, regarding strategies and performance, related to the separation between ownership and control. Finally, when independent committees exist in the boards of directors, mean-narrow-spectrum diversification is encouraged in the firms.Gobierno corporativo, diversificación estratégica, desempeño empresarial, propiedad familiar, consejos de administración
Search for nearby stars among proper motion stars selected by optical-to-infrared photometry. I. Discovery of LHS 2090 at spectroscopic distance of d=6pc
We present the discovery of a previously unknown very nearby star - LHS 2090
at a distance of only d=6 pc. In order to find nearby (i.e. d < 25 pc) red
dwarfs, we re-identified high proper motion stars ( 0.18 arcsec/yr) from
the NLTT catalogue (Luyten \cite{luyten7980}) in optical Digitized Sky Survey
data for two different epochs and in the 2MASS data base. Only proper motion
stars with large colour index and with relatively bright infrared
magnitudes () were selected for follow-up spectroscopy. The
low-resolution spectrum of LHS 2090 and its large proper motion (0.79
arcsec/yr) classify this star as an M6.5 dwarf. The resulting spectroscopic
distance estimate from comparing the infrared magnitudes of LHS 2090
with absolute magnitudes of M6.5 dwarfs is pc assuming an
uncertainty in absolute magnitude of 0.4 mag.Comment: 3 pages, 1 figure, accepted for publication in Astronomy and
Astrophysics Letter
O&M Models for Ocean Energy Converters: Calibrating through Real Sea Data
Of the cost centres that combine to result in Levelised Cost of Energy (LCOE), O&M costs play a significant part. Several developers have calculated component costs, demonstrating how they can become commercially competitive with other forms of renewable energy. However, there are uncertainties relating to the O&M figures that can only be reduced through lessons learned at sea. This work presents an O&M model calibrated with data from real sea experience of a wave energy device deployed at the Biscay Marine energy Platform (BiMEP): the OPERA O&M Model. Two additional case studies, utilising two other O&M calculation methodologies, are presented for comparison with the OPERA O&M Model. The second case study assumes the inexistence of an O&M model, utilising a Simplified Approach. The third case study applies DTOcean’s (a design tool for ocean energy arrays) O&M module. The results illustrate the potential advantages of utilising real sea data for the calibration and development of an O&M model. The Simplified Approach was observed to overestimate LCOE when compared to the OPERA O&M Model. This work also shows that O&M models can be used for the definition of optimal maintenance plans to assist with OPEX reduction.The authors are grateful to the European commission for funding the OPERA and EnFAIT projects as part of the Horizon 2020 framework. The authors also thankful to Oceantec-Idom for providing feedback to OPERA model’s inputs. A special thanks to Shona Pennock and Donald Noble for their diligent proofreading of this paper
Physical Structure of the Planetary Nebula NGC 3242 from the Hot Bubble to the Nebular Envelope
One key feature of the interacting stellar winds model of the formation of
planetary nebulae (PNe) is the presence of shock-heated stellar wind confined
in the central cavities of PNe. This so-called hot bubble should be detectable
in X-rays. Here we present XMM-Newton observations of NGC 3242, a
multiple-shell PN whose shell morphology is consistent with the interacting
stellar winds model. Diffuse X-ray emission is detected within its inner shell
with a plasma temperature ~2.35\times10^6 K and an intrinsic X-ray luminosity
~2\times10^30 ergs s^(-1) at the adopted distance of 0.55 kpc. The observed
X-ray temperature and luminosity are in agreement with "ad-hoc" predictions of
models including heat conduction. However, the chemical abundances of the
X-ray-emitting plasma seem to imply little evaporation of cold material into
the hot bubble, whereas the thermal pressure of the hot gas is unlikely to
drive the nebular expansion as it is lower than that of the inner shell rim.
These inconsistencies are compounded by the apparent large filling factor of
the hot gas within the central cavity of NGC 3242. Subject headings: planetary
nebulae: individual (NGC 3242)Comment: Accepted the publication in Astronomical Journa
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