Novel Ruthenium-Silver PTA-Based Polymers and Their Behavior in Water

New coordination polymers based on two metal-containing moieties Ru–Ag are synthesized: Na[RuCpX(PTA)-μ-(PTA)-1κP:2κ2N-AgX2]∞ (X = Cl (1), Br (2), I (3)). Characterization is performed by NMR, UV-visible and FT-IR spectroscopy, optical-electron microscopy, and elemental analyses (C, H, N, S). Light scattering is employed to characterize the colloidal particles growth by polymer self-assembling. These structures are stable over a broad range of pH and exhibit thermally-driven swelling, thus resembling a typical thermosensitive hydrogel

Socioeconomic background and academic achievement. The case of an argentine university

El objetivo de la investigación es determinar mediante regresiones estadísticas las relaciones entre las características socioeconómicas de los alumnos de las carreras de grado de la Universidad Nacional del Nordeste (UNNE, Argentina) y sus resultados académicos, y compararlos con los hallazgos de estudios similares efectuados en otras universidades nacionales. Se encuentra evidencia contundente de que las variables de Nivel Socioeconómico (NSE) son significativas para explicar las diferencias de rendimiento académico entre los alumnos de las facultades analizadas. Las variables que se han utilizado como indicadores de NSE elevado han presentado una correlación positiva, y las variables que se emplearon como indicadores de NSE más bajo han presentado una correlación negativa. Las variables sexo femenino, edad, estado civil casado y situación laboral inactiva están asociadas a un mejor rendimiento académico, mientras que las variables cantidad de hijos del estudiante, situación laboral ocupado, situación laboral desocupado, ausencia de cobertura médica y beneficiario de planes sociales están relacionadas a menores desempeños académicos. En materia de género, el hallazgo más relevante se manifiesta en los resultados de las estudiantes mujeres con hijos: su rendimiento es notoriamente inferior al de los estudiantes hombres con hijosThe aim of our research is to assess the relationships between socioeconomic characteristics of students in undergraduate courses of Northeastern University (UNNE, Argentina) and their academic results using statistical regression, and to compare the findings with the ones obtained in similar studies in other national universities. There is strong evidence that variables of Socioeconomic Status (SES) are significant in explaining the differences in academic achievement between students of the several schools. The variables used as indicators of high SES presented a positive correlation, and variables that were used as indicators of lower SES have presented a negative correlation. The variables female sex, age, married marital status and inactive employment status are associated with better academic performance, while the variables number of children of the student, busy employment status, employment status, medical coverage, and beneficiary of social plans are related to lower academic performance. Regarding gender, the most important finding is that female students with children have lower performance than male students with childre

La imagen es la clave: ausencia unilateral de una rama de la arteria pulmonar

Unilateral absence of pulmonary artery (UAPA) is a rare and underdiagnosed entity. Due to its va ried clinical expression, especially respiratory and most frequently associated with congenital heart disease, it can also present in isolation and remain asymptomatic for a long time. There is no consen sus on its treatment, which is generally reserved for the presence of complications, mainly pulmonary hypertension, hemoptysis, or recurrent respiratory infections. Objective: To describe two cases of UAPA identified early in life, and the usefulness of routine imaging tests for its diagnosis. Clinical Cases: We present two clinical cases of asymptomatic children referred for pediatric cardiological assessment. The first one was 1 month old, with a prenatal diagnosis of right aortic arch, that was referred to rule out associated anomalies. An echocardiographic evaluation confirmed left isolated UAPA, sustained by plain radiography. CT angiography confirmed UAPA and left lung hypoplasia. Only clinical follow-up was determined. The second case is a 2-week-old neonate who was referred due to a systolic murmur. Right pulmonary artery agenesis was diagnosed by echocardiography with no other associated defects and was confirmed by CT angiography. Plain chest radiography showed no alterations initially, however, after 1.5 months of follow-up, right lung collapse was detected so clinical follow-up was decided. Both cases were suspected by echocardiography and confirmed by CT angiography. At 1.5 years and 6 months old, respectively, they show a good evolution, with good growth, and close monitoring of their intercurrent respiratory processes. Conclusions: UAPA can be asymptomatic when occurs in isolation and go unnoticed. Through simple imaging methods, especially echocardiography, it can be suspected and must be confirmed later by CT angiography or MRI angiography

First exfoliated Ru–Ru–Au organometallic polymer with layered structure.

A new water soluble heterometallic polymeric complex [{(PTA)2 CpRu-l-CN-1jC:2j2N-RuCp(PTA)2}-l-{Au(CN)4}4]n 2H2O (1) is synthesized and characterized by single crystal X-ray diffraction. This complex self-assembles forming 3D polymeric structures with large scale hexagonal conformation. They also organize as 3D stacks of polymer sandwiches that can be exfoliated providing mono heterometallic-3D layers, as shown by electron microscopy. Regarding the polymer dynamics, quasi-elastic neutron scattering shows a transition from vibrational Debye–Waller behaviour to a more dynamically active state as a result of the loss of structural water molecules

Detection of very high energy gamma-ray emission from the gravitationally-lensed blazar QSO B0218+357 with the MAGIC telescopes

Context. QSO B0218+357 is a gravitationally lensed blazar located at a redshift of 0.944. The gravitational lensing splits the emitted radiation into two components, spatially indistinguishable by gamma-ray instruments, but separated by a 10-12 day delay. In July 2014, QSO B0218+357 experienced a violent flare observed by the Fermi-LAT and followed by the MAGIC telescopes. Aims. The spectral energy distribution of QSO B0218+357 can give information on the energetics of z ~ 1 very high energy gamma- ray sources. Moreover the gamma-ray emission can also be used as a probe of the extragalactic background light at z ~ 1. Methods. MAGIC performed observations of QSO B0218+357 during the expected arrival time of the delayed component of the emission. The MAGIC and Fermi-LAT observations were accompanied by quasi-simultaneous optical data from the KVA telescope and X-ray observations by Swift-XRT. We construct a multiwavelength spectral energy distribution of QSO B0218+357 and use it to model the source. The GeV and sub-TeV data, obtained by Fermi-LAT and MAGIC, are used to set constraints on the extragalactic background light. Results. Very high energy gamma-ray emission was detected from the direction of QSO B0218+357 by the MAGIC telescopes during the expected time of arrival of the trailing component of the flare, making it the farthest very high energy gamma-ray sources detected to date. The observed emission spans the energy range from 65 to 175 GeV. The combined MAGIC and Fermi-LAT spectral energy distribution of QSO B0218+357 is consistent with current extragalactic background light models. The broad band emission can be modeled in the framework of a two zone external Compton scenario, where the GeV emission comes from an emission region in the jet, located outside the broad line region.Comment: 11 pages, 6 figures, accepted for publication in A&

Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies

We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 observations with MAGIC with 6-year observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain limits on the annihilation cross-section for dark matter particle masses between 10 GeV and 100 TeV - the widest mass range ever explored by a single gamma-ray analysis. These limits improve on previously published Fermi-LAT and MAGIC results by up to a factor of two at certain masses. Our new inclusive analysis approach is completely generic and can be used to perform a global, sensitivity-optimized dark matter search by combining data from present and future gamma-ray and neutrino detectors.Comment: 19 pages, 3 figures. V2: Few typos corrected and references added. Matches published version JCAP 02 (2016) 03

Investigating the peculiar emission from the new VHE gamma-ray source H1722+119

The MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes observed the BL Lac object H1722+119 (redshift unknown) for six consecutive nights between 2013 May 17 and 22, for a total of 12.5 h. The observations were triggered by high activity in the optical band measured by the KVA (Kungliga Vetenskapsakademien) telescope. The source was for the first time detected in the very high energy (VHE, $E > 100$ GeV) $\gamma$-ray band with a statistical significance of 5.9 $\sigma$. The integral flux above 150 GeV is estimated to be $(2.0\pm 0.5)$ per cent of the Crab Nebula flux. We used contemporaneous high energy (HE, 100 MeV $< E < 100$ GeV) $\gamma$-ray observations from Fermi-LAT (Large Area Telescope) to estimate the redshift of the source. Within the framework of the current extragalactic background light models, we estimate the redshift to be $z = 0.34 \pm 0.15$. Additionally, we used contemporaneous X-ray to radio data collected by the instruments on board the Swift satellite, the KVA, and the OVRO (Owens Valley Radio Observatory) telescope to study multifrequency characteristics of the source. We found no significant temporal variability of the flux in the HE and VHE bands. The flux in the optical and radio wavebands, on the other hand, did vary with different patterns. The spectral energy distribution (SED) of H1722+119 shows surprising behaviour in the $\sim 3\times10^{14} - 10^{18}$ Hz frequency range. It can be modelled using an inhomogeneous helical jet synchrotron self-Compton model.Comment: 12 pages, 5 figures, 2 table

MAGIC detection of short-term variability of the high-peaked BL Lac object 1ES 0806+524

The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in VHE $\gamma$ rays in 2008. Until now, the broad-band spectrum of 1ES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwavelength observations from $\gamma$ rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of 1ES 0806+524 to date. The stereoscopic MAGIC observations yielded a $\gamma$-ray signal above 250 GeV of $(3.7 \pm 0.7)$ per cent of the Crab Nebula flux with a statistical significance of 9.9 $\sigma$. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE $\gamma$-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in 1ES 0806+524. The spectrum of this flare is well described by a power law with a photon index of $2.97 \pm 0.29$ between $\sim$150 GeV and 1 TeV and an integral flux of $(9.3 \pm 1.9)$ per cent of the Crab Nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. The broad-band spectral energy distribution can be described with a one-zone Synchrotron Self Compton model with parameters typical for HBLs, indicating that 1ES 0806+524 is not substantially different from the HBLs previously detected.Comment: 12 pages, 8 figures, 3 tables, accepted 2015 April 20 for publication in Monthly Notices of the Royal Astronomical Society Main Journa

Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year time scales, which can bring additional insight on the processes responsible for its broadband emission. We observed Mrk 421 in the very high energy (VHE) gamma-ray range with the Cherenkov telescope MAGIC-I from March 2007 to June 2009 for a total of 96 hours of effective time after quality cuts. The VHE flux variability is quantified with several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes for the first time. The 2.3 year long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Mets\"ahovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year time scales. Mrk 421 was found in different gamma-ray emission states during the 2.3 year long observation period. Flares and different levels of variability in the gamma-ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Mets\"ahovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. The fractional variability is overall increasing with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and gamma-ray photons are either the same, as expected in the Synchrotron-Self-Compton mechanism, or at least strongly correlated, as expected in electromagnetic cascades.Comment: Corresponding authors: Ann-Kristin Overkemping ([email protected]), Marina Manganaro ([email protected]), Diego Tescaro ([email protected]), To be published in Astronomy&Astrophysics (A&A), 12 pages, 9 figure