Transcription of satellite DNAs in insects

Chromatin condensation is an important regulatory mechanism of gene silencing as well as gene activation for the hundreds of functional protein genes harbored in heterochromatic regions of different insect species. Being the major heterochromatin constituents, satellite DNAs serve important roles in heterochromatin regulation in insect in general. Their expression occurs in all developmental stages, being the highest during embryogenesis. Satellite DNA transcrips range from small RNAs, corresponding in size to siRNA, and piwiRNAs, to large, a few Kb long RNAs. The long transcripts are preferentially nonpolyadenylated and remain in the nucleus. The actively regulated expression of satDNAs by cis or trans elements as well as by environmental stress, rather than constitutive transcription, speaks in favour of their involvement in differentiation, development, and environmental response

La trascendencia económica del trabajo autónomo

La importancia económica del trabajo autónomo no se circunscribe a su contribución a la creación de empleo y de renta, aún siendo ésta ya de por sí relevante. Más allá de este efecto directo, el trabajo autónomo asume un papel indispensable en el funcionamiento de cualquier de economía de mercado, al constituir un germen fundamental en la generación de nuevo tejido empresarial. El análisis de la significación del trabajo autónomo en nuestro entorno exige profundizar en las razones económicas que propician esta actividad profesional. Las motivaciones del trabajador autónomo condicionan las consecuencias del fenómeno, no sólo a nivel individual, sino, lo que es más trascendente, desde la óptica del proceso de crecimiento y desarrollo económico. A este respecto, la distinción entre trabajo autónomo por «necesidad» o por «oportunidad» resulta de especial valor analítico cuando se trata de indagar en la repercusión económica del autoempleo. Adicionalmente, un conjunto heterogéneo de factores delimitan la «calidad» del empresario-autónomo, condicionando el ejercicio de su actividad y los resultados de la misma, para manifestarse, a nivel macroeconómico, en la «calidad» del tejido empresarial

Pyroclasts of the first phases of the explosive-effusive PCCVC volcanic eruption: physicochemical analysis

The morphology, texture, grain size and other physicochemical characteristics of pyroclastic material from the first phases of the Puyehue-Cordon Caulle volcanic complex (PCCVC) eruption, (Southern Andes, Chile), can be associated to the model recently reported for the magma storage and its ascent conditions. The eruption started June 4th 2011, and the studied volcanic material corresponds to that collected in Argentine territory at different distances from the source, between 4 and 12 June 2011. The explosive-effusive volcanic process of the first days occurred with the simultaneous emplacement of lava flows and the venting of pyroclastic material, ejecting two well differentiated types of particles. The more abundant was constituted by rhyolitic and light color pumice fragments, characterized by a typical vesicular texture, easy fragmentation and absence of occluded crystalline phases. Particles found in minor proportion were dark color, different in shape and texture and rich in Fe and Ti. They seemed to be more effective for the interaction with emitted gases in the upper part of the column, for this reason, they appeared partially covered by condensation products. The ascent conditions of the magma affected its rheological behavior through variations in the degassing, viscosity and fragmentation. On the other hand, distance to the source, depositional time, volcanic evolution and environmental conditions are factors that affect the chemical composition of collected ash. So, the SiO2/FeO ratio not only increases with the distance but also with the deposition time and volcanic activity. The work was done with the aid of several techniques such as a laser-sediment analyzer, X-ray diffraction (XRD), chemical analysis (bulk and surface), SEM microscopy and Raman “microprobe” spectroscopy. On the other hand, the physicochemical behavior of the pyroclastic material allows us to suggest eventual applications

Fragmentation and complexity: analyzing structural change in the Chicago regional economy

In this paper, two dimensions are differentiated within the fragmentation process: a spatial and a functional one. On the one hand, due to fragmentation and industrial relocation, regional and national economies might be losing some internal linkages. This spatial fragmentation determines a decrease in the complexity of the production systems. On the other hand, outsourcing, as a form of functional fragmentation, increases the density of transactions and linkages within an economy. The overall impact of fragmentation on the complexity of the regional and national economic systems depends on the net effect of these two fragmentation forces. In this paper, the effects of fragmentation on the complexity of the economy of the Chicago region are studied from a set of input-output tables estimated for the period 1978-2014 using Average Propagation Lengths (APLs)

Effects of introgressed 4Nv Aegilops ventricosa chromosome on yield and yield components in bread wheat.

Effects of introgressed 4Nv Aegilops ventricosa chromosome on yield and yield components in bread whea

Semicontinuous Temperature-Phased Anaerobic Digestion (TPAD) of Organic Fraction of Municipal Solid Waste (OFMSW). Comparison with single-stage processes

The optimization of anaerobic digestion of organic wastes is a challenge to maximize energy production through biogas production process. In this study, semicontinuous TPAD (Temperature Phased Anaerobic Digestion) process has been used for the treatment of the Organic Fraction of Municipal Solid Waste (OFMSW) coming from a mechanical–biological-treatment (MBT) plant. TPAD combines the advantages of operating in different temperature ranges getting better efficiencies of organic matter removal and higher methane productivities than single-stage anaerobic digestion. In this study, the configuration used in the overall process was a thermophilic reactor (55–57 C) for the first phase followed by a mesophilic one (35–37 C) for the second phase. Two TPAD conditions have been tested in this paper: 4:10 and 3:6. The first digit means the SRT used in the first thermophilic phase while the second digit is related to the SRT used in the second mesophilic phase. Moreover, the performance of TPAD processes was compared with those from single-stage digesters operating at similar SRT (i.e., mesophilic and thermophilic reactors operating at 15 days SRT and thermophilic reactor operating at 10 days). The results showed that achievement reached in TPAD 4:10 was better than the corresponding one in TPAD 3:6, obtaining higher productivity of methane (35–45%) and removal of organic matter (6–19%). Moreover, the results indicate that TPAD processes reach higher efficiencies for organic matter removal (16%, 10% and 30% for DOC, CODsoluble and VS, respectively) and higher methane yields (26–60%) than single-stage systems operating at similar SRT

Experimental and numerical study on a freeze protection system for flat-plate solar collectors with silicone peroxide tubes

The freeze protection is essential in the majority of solar thermal installations to prevent breakage of solar thermal collectors. Therefore, there are different methods of protection against freezing of flat plate solar thermal collectors, all of them with certain limitations. This paper shows a novel freeze protection mechanism in the solar thermal collector by using flexible silicone peroxide tubes inside the absorber of the solar collector. We demonstrate, in a theoretical and experimental way, that the increase of volume and pressure produced inside a solar collector during freezing process can be absorbed using a flexible silicone peroxide tubes under all exposure conditions. The parameters that optimize the geometric configuration of the solution proposed have been calculated. A collector prototype with silicones peroxide has experimentally complied with the Standard ISO 9806:20 13, including freeze resistance test, without any significantly influence on its efficiency or pressure drop. Therefore, the solution proposed presents an inexpensive, effective, reliable and maintenance-free freeze protection system for flat plate solar collectors

Pedagogical Use of Automatic Graders

Non

A new method for quantification of hepatobiliary scintigraphy using 99mTc-mebrofenin. A comparative study

A method based upon the application of mathematical techniques of deconvolution on the classical compartmental model for the quantitative study of liver function from hepatobiliary scintigraphy using 99mTc-mebrofenin data is proposed. The theory in which the method is based upon is presented and a comparison with a published methodology of obtaining the hepatic extraction after scintigraphic sudies has been performed using the results on 36 rats studies obtained with the two methods. A highly significant correlation between the two techniques was verified. The characteristics of the two methodologies, the proposed one based upon a theoretical approach and the other one on an empirical approximation are discussed. Comments are made on the interest and limitations of the presented technique that may be an useful tool for the evaluation of hepatic insufficiency