Lectura y biblioteca pública: perspectivas sociales en el discurso de la modernidad

This article is a reflection about the public libraries' social function and the reading practices. It analyzes their relation with the instrumentalization of the rational thought and its incidence on social library speech. This article reflects the concept of civic responsibility on the frame of this instrumentalization, emphasizing the multilateral organizations dispositions to the library labor development in the Latin American countries. Finally, it suggests methods that will contribute to decrease the contradictory situation of the public library dominated by the tension between the basic management of social principles and the tendency that sometimes gain the social concepts in the public discussion

Porous Titanium surfaces to control bacteria growth: mechanical properties and sulfonated polyetheretherketone coating as antibiofounling approaches

Here, titanium porous substrates were fabricated by a space holder technique. The relationship between microstructural characteristics (pore equivalent diameter, mean free-path between pores, roughness and contact surface), mechanical properties (Young’s modulus, yield strength and dynamic micro-hardness) and bacterial behavior are discussed. The bacterial strains evaluated are often found on dental implants: Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. The colony-forming units increased with the size of the spacer for both types of studied strains. An antibiofouling synthetic coating based on a sulfonated polyetheretherketone polymer revealed an effective chemical surface modification for inhibiting MRSA adhesion and growth. These findings collectively suggest that porous titanium implants designed with a pore size of 100–200 µm can be considered most suitable, assuring the best biomechanical and bifunctional anti-bacterial properties.University of Seville VI Plan Propio de Investigación y Transferencia—US 2018, I.3A

Biosynthesis of gold and silver nanoparticles using Parkinsonia florida leaf extract and antimicrobial activity of silver nanoparticles

In this work, the biosynthesis of gold and silver nanoparticles from a leaf extract of Parkinsonia florida (P. florida) is reported. The P. florida leaf extract was analyzed by a phytochemical screening, by measuring the DPPH radical scavenging activity, and by Fourier-transform infrared spectroscopy (FT-IR). The phytochemical screening results indicated that biomolecules like carbohydrates, phenols, proteins, aminoacids, saponins, and flavonoids present in P. florida leaf extract might have participated in the chemical reduction of the metallic salts and further colloidal stabilization. The FT-IR results from leaf extract functional groups support the role of surface modification with the presence of residues of phenols, proteins, aminoacids, saponins, and flavonoids. The formation of metallic nanoparticles was confirmed by optical absorption spectroscopy with characteristic absorption bands at 550 nm and 430 nm, for gold and silver nanoparticles, respectively. Zeta potential for gold nanoparticles presents negative values in the range of 10 +/- 1 to 16 +/- 1 mV, depending on the amount of leaf extract used during the synthesis reaction. Similarly, zeta potential values for silver nanoparticles were in the range of -5 +/- 1 to 16 +/- 1 mV. STEM images revealed the average particles sizes in the range from 10 to 15 nm, and 10 to 57 nm, for gold and silver nanoparticles respectively. The silver nanoparticles presented good antibacterial activity, inhibiting the growth of Staphylococcus aureus and Escherichia coli.National Council of Science and Technology (CONACyT) [INFR-226208-2014, INFR-255791-2015]; CONACYTOpen access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Molecular dynamics simulations of glassy polymers

We review recent results from computer simulation studies of polymer glasses, from chain dynamics around the glass transition temperature Tg to the mechanical behaviour below Tg. These results clearly show that modern computer simulations are able to address and give clear answers to some important issues in the field, in spite of the obvious limitations in terms of length and time scales. In the present review we discuss the cooling rate effects, and dynamic slowing down of different relaxation processes when approaching Tg for both model and chemistry-specific polymer glasses. The impact of geometric confinement on the glass transition is discussed in detail. We also show that computer simulations are very useful tools to study structure and mechanical response of glassy polymers. The influence of large deformations on mechanical behaviour of polymer glasses in general, and strain hardening effect in particular are reviewed. Finally, we suggest some directions for future research, which we believe will be soon within the capabilities of state of the art computer simulations, and correspond to problems of fundamental interest.Comment: To apear in "Soft Matter

Autoimmunity and COPD: clinical implications.

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Long term cigarette smoking is the cause of more than 90% of COPD in Westernized countries. However, only a fraction of chronic heavy smokers develop symptomatic COPD by the age of 80 years. COPD is characterized by an abnormal immune response in the lower airways and its progression is associated with infiltration of the lung by innate and adaptive inflammatory immune cells that form lymphoid follicles. There is growing evidence that both cellular- and antibody-mediated autoimmunity has a fundamental role in the pathogenesis of stable COPD. In particular, carbonyl-modified proteins may help to drive autoimmunity in COPD and to cause the characteristic small airways abnormalities and even contribute to the pathogenesis of pulmonary emphysema. Although direct, indirect, and circumstantial evidence of a role for autoimmunity in stable COPD patients has been identified, no cause-and-effect relationship between autoimmunity and the mechanisms of COPD has been firmly established in man. As such the potential contribution of an autoimmune response to the pathogenesis of COPD exacerbation is still being investigated and represents an area of active research. Many drugs targeting autoimmune responses are already available and the results of controlled clinical trials are awaited with great interest. The potential for measuring specific serum autoantibodies as biomarkers to predict clinical phenotypes or progression of stable COPD is promising

The CCR4-NOT Complex Is Implicated in the Viability of Aneuploid Yeasts

To identify the genes required to sustain aneuploid viability, we screened a deletion library of non-essential genes in the fission yeast Schizosaccharomyces pombe, in which most types of aneuploidy are eventually lethal to the cell. Aneuploids remain viable for a period of time and can form colonies by reducing the extent of the aneuploidy. We hypothesized that a reduction in colony formation efficiency could be used to screen for gene deletions that compromise aneuploid viability. Deletion mutants were used to measure the effects on the viability of spores derived from triploid meiosis and from a chromosome instability mutant. We found that the CCR4-NOT complex, an evolutionarily conserved general regulator of mRNA turnover, and other related factors, including poly(A)-specific nuclease for mRNA decay, are involved in aneuploid viability. Defective mutations in CCR4-NOT complex components in the distantly related yeast Saccharomyces cerevisiae also affected the viability of spores produced from triploid cells, suggesting that this complex has a conserved role in aneuploids. In addition, our findings suggest that the genes required for homologous recombination repair are important for aneuploid viability

Operations of and Future Plans for the Pierre Auger Observatory

Technical reports on operations and features of the Pierre Auger Observatory, including ongoing and planned enhancements and the status of the future northern hemisphere portion of the Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200

Highlights from the Pierre Auger Observatory

The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a number of major breakthroughs. Among these we discuss the energy spectrum and the searches for large-scale anisotropies. We present analyses of our X$_{max}$ data and show how it can be interpreted in terms of mass composition. We also describe some new analyses that extract mass sensitive parameters from the 100% duty cycle SD data. A coherent interpretation of all these recent results opens new directions. The consequences regarding the cosmic ray composition and the properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray Conference, Rio de Janeiro 201

Searching for a Stochastic Background of Gravitational Waves with LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed the fourth science run, S4, with significantly improved interferometer sensitivities with respect to previous runs. Using data acquired during this science run, we place a limit on the amplitude of a stochastic background of gravitational waves. For a frequency independent spectrum, the new limit is $\Omega_{\rm GW} < 6.5 \times 10^{-5}$. This is currently the most sensitive result in the frequency range 51-150 Hz, with a factor of 13 improvement over the previous LIGO result. We discuss complementarity of the new result with other constraints on a stochastic background of gravitational waves, and we investigate implications of the new result for different models of this background.Comment: 37 pages, 16 figure