Exploring DNA Compaction Via Bacillus Subtilis ParB Protein by Single Molecule Investigation

Faithful chromosome segregation involves ParB, a DNA-binding and compacting protein that specifically recognizes parS DNA sites near the replication origin. ParB spreads 10-20 kb from parS sites, which recruitments additional ParB molecules to neighboring DNA, forming higher-order nucleoprotein complexes. ParB is also a novel CTPase enzyme and hydrolyses CTP to self-dimerization and create a clamp that slides along DNA. To understand the roles of CTP in Bacillus subtilis ParB (BsParB), we purified wild type ParB (BsParB (WT)) and recombinant ParB (BsParB(R80A)) mutant. BsParB(R80A) was known to prevent CTP binding and not compact DNA. Proteins N- and C-terminally appended with a lysine-cysteine-lysine (KCK) tag were tested. We performed single-molecule DNA flow-stretching experiments both in the absence and presence of CTP. Both CTP binding and CTP hydrolysis impacts ParB-mediated DNA compaction, with parS sites modulating compaction rates, while BsParB(R80A) could compact DNA in a CTP-dependent manner. The KCK tag influenced DNA compaction

Inter- and intra-layer excitons in MoS2_2/WS2_2 and MoSe2_2/WSe2_2 heterobilayers

Accurately described excitonic properties of transition metal dichalcogenide heterobilayers (HBLs) are crucial to comprehend the optical response and the charge carrier dynamics of them. Excitons in multilayer systems posses inter or intralayer character whose spectral positions depend on their binding energy and the band alignment of the constituent single-layers. In this study, we report the electronic structure and the absorption spectra of MoS$_2$/WS$_2$ and MoSe$_2$/WSe$_2$ HBLs from first-principles calculations. We explore the spectral positions, binding energies and the origins of inter and intralayer excitons and compare our results with experimental observations. The absorption spectra of the systems are obtained by solving the Bethe-Salpeter equation on top of a G$_0$W$_0$ calculation which corrects the independent particle eigenvalues obtained from density functional theory calculations. Our calculations reveal that the lowest energy exciton in both HBLs possesses interlayer character which is decisive regarding their possible device applications. Due to the spatially separated nature of the charge carriers, the binding energy of inter-layer excitons might be expected to be considerably smaller than that of intra-layer ones. However, according to our calculations the binding energy of lowest energy interlayer excitons is only $\sim$ 20\% lower due to the weaker screening of the Coulomb interaction between layers of the HBLs. Therefore, it can be deduced that the spectral positions of the interlayer excitons with respect to intralayer ones are mostly determined by the band offset of the constituent single-layers. By comparing oscillator strengths and thermal occupation factors, we show that in luminescence at low temperature, the interlayer exciton peak becomes dominant, while in absorption it is almost invisible.Comment: 17 pages, 4 figure

Organización industrial de los servicios de salud en Chile

El sistema de salud chileno presenta características únicas. En el país existe un mandato que obliga a los trabajadores activos y pasivos a cotizar un 7% de su ingreso para adscribirse junto a sus dependientes a un sistema de seguro de salud. Esta adscripción obligatoria puede ser al sistema público, el cual se organiza a través de una modalidad solidaria tradicional de seguridad social, o bien al sistema privado, el cual ofrece seguros de salud que obedecen a una lógica de tipo individual. La elección de uno de los sistemas es voluntaria, pero las características de los seguros ofrecidos y su precio de acceso producen una segmentación del mercado de manera tal que las personas de mayores ingresos y menor riesgo se orientan hacia el sector privado de las ISAPRE (Instituciones de Salud Previsional) y aquellos de menores ingresos y mayor riesgo de salud son atendidos en el sistema público.

Excitons in boron nitride single layer

Boron nitride single layer belongs to the family of 2D materials whose optical properties are currently receiving considerable attention. Strong excitonic effects have already been observed in the bulk and still stronger effects are predicted for single layers. We present here a detailed study of these properties by combining \textit{ab initio} calculations and a tight-binding-Wannier analysis in both real and reciprocal space. Due to the simplicity of the band structure with single valence ($\pi$) and conduction ($\pi^*$) bands the tight-binding analysis becomes quasi quantitative with only two adjustable parameters and provides tools for a detailed analysis of the exciton properties. Strong deviations from the usual hydrogenic model are evidenced. The ground state exciton is not a genuine Frenkel exciton, but a very localized "tightly-bound" one. The other ones are similar to those found in transition metal dichalcogenides and, although more localized, can be described within a Wannier-Mott scheme

Etapa diagnostica del sistema de gestión de la seguridad y salud en el trabajo de la empresa Almacén militar 2M

La seguridad y salud en el trabajo actualmente representa una de las herramientas más importantes para mejorar la calidad de vida de las organizaciones y con ella su competitividad. Esto se hace posible siempre y cuando en la organización se promueva y estimule en todo momento la creación de una cultura del cuidado y la prevención. Es así que en el presente trabajo se hace una propuesta de elaborar un Diagnóstico del sistema de gestión se seguridad y salud en el trabajo con el propósito de identificar en qué condiciones se encuentra la empresa y qué medidas se implementaran para corregir estas y así obtener un mejoramiento continuo en sus procesos con el fin de mejorar la calidad de vida laboral , lograr reducir los costos generados por accidentes de trabajo y las enfermedades laborales, mejorar la calidad de vida de los servicios y ante todo generar ambientes sanos y seguros a su personal

Becoming Part of an Eco-Community : Social and Environmental Activism or Livelihood Strategy?

Studying grassroots initiatives which aim to respond to environmental and social crisis is of renewed importance nowadays, in the aftermath of the 2008-9 financial crisis in southern Europe. This paper studies people's motivations for becoming part of an eco-community in Catalonia, Spain, through interviews with 29 informants. The research is part of a larger study, based on ethnographic data collected between 2013 and 2015 in 27 eco-communities. The paper shows the extent to which people who joined an eco-community were driven by ideological reasons, adopting a livelihood strategy, or by a combination of both factors in the years following the crisis. We argue that the social and economic crisis has had an impact on the factors motivating people to join these communities, with an increase in the number of people driven by materialistic motives, relative to those who joined for ideological reason

Industrial districts and migrant enclaves : a model of interaction

So far, the relationship between Industrial Districts (IDs; clusters of interconnected local industries) and migrant enclaves (areas with a high concentration of international migrants from a single nationality) has been studied mostly by focusing on the emergence of 'ethnic enclave economies' within the district and/or by highlighting racist conflicts that achieved notoriety in the media. In this study, we contend that there is a more general and complex interaction between the two phenomena. This interaction is mediated by the local context, national regulations, and the organization of the international market, among other factors. By focusing on the case of the ceramic ID of Castelló de la Plana (Spain), we show how this ID with a high rate of job formality, combined with other job opportunities and a unique 'institutional completeness', set up the conditions for a non-conflictive Romanian migrant enclave that reached 14% of the town's total population in 2012. Finally, and also considering another case study of ID and migrant enclave (Prato, and its Chinese enclave), we suggest a model of interaction that should be interpreted taking into account the general dynamics of the international organization of value and the requirements of flexibility and reduction of costs that frame ID

Quantum interference effects in resonant Raman spectroscopy of single- and triple-layer MoTe2_2 from first principles

We present a combined experimental and theoretical study of resonant Raman spectroscopy in single- and triple-layer MoTe$_2$. Raman intensities are computed entirely from first principles by calculating finite differences of the dielectric susceptibility. In our analysis, we investigate the role of quantum interference effects and the electron-phonon coupling. With this method, we explain the experimentally observed intensity inversion of the $A^\prime_1$ vibrational modes in triple-layer MoTe2 with increasing laser photon energy. Finally, we show that a quantitative comparison with experimental data requires the proper inclusion of excitonic effects.Comment: Main Text (5 Figures, 1 Tables) + Supporting Information (6 Figures

Catedral de Toledo: características, estructura constructiva y reconstrucción virtual de la encuadernación de diez cantorales, s. XVI-XVIII

This article examines the material and physical features of ten choir books from Toledo Cathedral, dating from the 16th to the 18th centuries. They are virtually reconstructed in 3D allowing us to visualise how the various elements of the wooden boards were put together and the design of the covers. This innovatory method of reconstructing the choir books adds to the information provided by other researchers who use different techniques such as X-rays. Other features of the bindings are also described, such as how the bands and headbands are attached to the boards, how the binding’s leather is affixed, and how various metal pieces, like ornaments, corners or clasps, are secured.A través de este estudio se analizan las características materiales y físicas de diez libros cantorales o de facistol de la catedral de Toledo, datados entre los siglos XVI-XVIII. Se ofrece su reconstrucción virtual en 3D permitiendo visualizar cómo se hicieron los ensamblajes de las diversas piezas que forman las tapas de madera junto al esquema de las cubiertas, este sistema de reconstrucción ofrece datos nuevos a los presentados por otros autores con otras técnicas, como los rayos X. También se describen los demás elementos que forman la encuadernación, como la unión de los nervios y de las cabezadas a las tapas, el montaje de la piel de la encuadernación o las diversas piezas metálicas (bullones, cantoneras, cierres…)

When networks speak volumes: Variation in the size of broader acquaintanceship networks

Personal network researchers have extensively studied the characteristics and effects of individuals' closest relationships, but they have paid much less attention to broader acquaintanceship networks, despite evidence that weak ties can also provide social support. In this paper we focus on one aspect of these networks: acquaintanceship volume. We estimate its distributional parameters for a large, representative sample of the general population of Spain, explore its variation across social groups as well as its implications for social support availability. We designed a survey instrument based on the Network Scale-Up Method and implemented it in a national survey in Spain. Our results suggest that Spaniards have approximately 536 acquaintances, with a large inter-individual variation, comparable to the estimates reported for the American population. Acquaintanceship volume varies with gender, age, education, and income. These differences are partially related to the unequal participation of social groups in voluntary associations, confirming the civic value of such associations, and in employment. Even with similar core network size, acquaintanceship volume increases the likelihood of having adequate social support available, suggesting that broader acquaintanceship networks also structure individual outcomes