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The VISCACHA (VIsible Soar photometry of star Clusters in tApii and Coxi HuguA†) Survey is an ongoing project based on deep and spatially resolved photometric observations of Magellanic Cloud star clusters, collected using the SOuthern Astrophysical Research (SOAR) telescope together with the SOAR Adaptive Module Imager. So far we have used >300h of telescope time to observe ∼150 star clusters, mostly with low mass (M < 104M⊙) on the outskirts of the LMC and SMC. With this high-quality data set, we homogeneously determine physical properties using deep colour-magnitude diagrams (ages, metallicities, reddening, distances, mass, luminosity and mass functions) and structural parameters (radial density profiles, sizes) for these clusters which are used as a proxy to investigate the interplay between the Magellanic Clouds and their evolution. We present the VISCACHA survey and its initial results, based on our first two papers. The project’s long term goals and expected legacy to the community are also addressed.
Investigations into the existence of life in other parts of the cosmos find strong parallels with studies of the origin and evolution of life on our own planet. In this way, astrobiology and paleobiology are married by their common interest in disentangling the interconnections between life and the surrounding environment. In this way, a cross-point of both sciences is paleometry, which involves a myriad of imaging and geochemical techniques, usually non-destructive, applied to the investigation of the fossil record. In the last decades, paleometry has benefited from an unprecedented technological improvement, thus solving old questions and raising new ones. This advance has been paralleled by conceptual approaches and discoveries fuelled by technological evolution in astrobiological research. In this context, we present some new data and review recent advances on the employment of paleometry to investigations on paleobiology and astrobiology in Brazil in areas such biosignatures in Ediacaran microbial mats, biogenicity tests on enigmatic Ediacaran structures, research on Ediacaran metazoan biomineralization, fossil preservation in Cretaceous insects and fish, and finally the experimental study on the decay of fish to test the effect of distinct types of sediment on soft-tissue preservation, as well as the effects of early diagenesis on fish bone preservation.
MG/HK was introduced into CMOS technology and enabled scaling beyond the 45/32nm technology node. The change in gate stack from poly-Si/SiON to MG/HK introduced new reliability challenges like the positive bias temperature instability (PBTI) and stress induced leakage currents (SILC) in nFET devices which prompted thorough investigation to provide fundamental understanding of these degradation mechanisms and are nowadays well understood. The shift to a dual-layer gate stack also had a profound impact on the time dependent dielectric breakdown (TDDB) introducing a strong polarity dependence in the model parameter. As device scaling continues, stochastic modeling of variability, both at time zero and post stress due to BTI, becomes critical especially for SRAM circuit aging. As we migrate towards novel device architectures like bulk FinFET, SOI FinFETs, FDSOI and gate-all-around devices, impact of self-heating needs to be accounted for in reliability testing.
In this paper we summarize the fundamentals of MG/HK reliability and discuss the reliability and characterization challenges related to the scaling of future CMOS technologies.
We observed the Planetary Nebula NGC 6720 with the Gemini Telescope and the Gemini Multi-Object Spectrographs. We obtained spatial maps of 36 emission-lines in the wavelength range between 3600 Å and 9400 Å. We derived maps of c(Hβ), electronic densities, electronic temperatures, ionic and elemental abundances, and Ionization Correction Factors (ICFs) in the source and investigated the mass-loss history of the progenitor. The elemental abundance results indicate the need for ICFs based on three-dimensional photoionization models.
What’s fair? The cries of the playground – “that’s fair,” “that’s not fair” – echo throughout our adult lives. Sometimes an entire society’s understanding of what’s fair shifts in a decade, a year, even a single day. Children of Jehovah’s Witnesses refuse to salute the flag in school and change the way a nation views the First Amendment. Oliver Brown thinks it’s unfair that his daughter can’t attend her neighborhood school. Rosa Parks refuses to give up her seat on a Montgomery bus. Together they change definitions of what counts as equality. Sometimes you go to sleep one night, and when you wake up, the rules have changed. That happened on November 22, 1971, when the U.S. Supreme Court ruled for the first time that arbitrary discrimination on the basis of sex could be a denial of equal protection of the laws.
The case that triggered this shift was a modest one. It came from a small state (Idaho) and involved hardly any money ($930, which lawyers’ fees completely consumed). To most people, the dispute seemed merely a family squabble, hardly worth the expensive attention it would get. It is the rare constitutional law casebook in which it figures in more than a footnote. Yet Sally Reed’s complaint was far from trivial. It disrupted well-established rules of fairness and spurred broad social transformation in the ways that both men and women make some of the most important choices in their lives.
We introduce a strategy based on Kustin–Miller unprojection that allows us to construct many hundreds of Gorenstein codimension 4 ideals with 9×16 resolutions (that is, nine equations and sixteen first syzygies). Our two basic games are called Tom and Jerry; the main application is the biregular construction of most of the anticanonically polarised Mori Fano 3-folds of Altınok’s thesis. There are 115 cases whose numerical data (in effect, the Hilbert series) allow a Type I projection. In every case, at least one Tom and one Jerry construction works, providing at least two deformation families of quasismooth Fano 3-folds having the same numerics but different topology.
The enormous burden of almost 3.6 million neonatal deaths remains relatively invisible because of gaps in data or ineffective use of existing data, the perceived complexity and expense of solutions, and societal norms for seclusion of newborns and acceptance of neonatal deaths.
The data for action for neonatal survival highlight many commonalities with maternal survival and indeed mothers and their babies are intimately linked. Stillbirths are not mentioned in Millennium Development Goal (MDG) 4 or 5, yet they are largely preventable with the same solutions. Previous false dichotomies in advocacy and programmes for maternal and newborn survival have not been helpful in accelerating progress. An integrated call for action would be more likely to increase global visibility and national action. Health professionals and policy makers need to link numbers for mothers, newborns and stillbirths together, and to work together to implement the highest impact solutions that save women and babies.
This chapter reviews the progress for MDG 4 (child survival), with a focus on neonatal survival and on highlighting linkages with MDG 5 (maternal survival). Priorities for programmatic action based on the data are identified.
Progress for neonatal and child survival
The MDGs are the most widely ratified health and development targets ever. Nearly every nation has agreed to reach these eight interlinking goals that address poverty, hunger, education and health by 2015. Multiple reports have been published and many commitments have been agreed but is progress being made?
VISIR, the VLT Imager and Spectrograph for the Mid-Infrared is a multi-mode instrument, featuring also a high resolution Echelle spectrograph with a spectral resolving power of ≈30 000 or 10 km s−1 at ν ≈ 30 000 GHz (λ ≈ 10 μm). A limited long-slit mode as well as a general cross-dispersed mode are available. The Echelle grating is illuminated with a 200 mm diameter collimated beam. Cross-dispersion is achieved by a pair of grisms in the pre-slit optics. The entire frequency interval corresponding to the “10 μ m-window” from 22 400 to 39 500 GHz is fully accessible, albeit sequentially. This interval contains a multitude of fundamental molecular rotational-vibrational bands such as SiO, OH−, H2O, NH3, CH4 and many other hydro-carbonates. Since its commissioning in April 2004, VISIR has been plagued by artifacts introduced from its detector. The cross-dispersed mode is especially handicapped, as it is the most demanding mode for dynamic range of illumination. Now an ambitious upgrade with a pair of newly developed 1k2 As:Si detectors is underway, which will fully resurrect the spectroscopic mode. This will also increase the frequency interval accessible in one exposure by 240% while changing from critical to 3-pixel sampling. Even in the absence of extra spectral features this increase is quite valuable for absorption line spectroscopy, as the limiting factor in analysis often is the definition of the photospheric continuum.
Water vapour is the principle source of opacity at infrared wavelengths in the earth's atmosphere. Measurements of atmospheric water vapour serve two primary purposes when considering operation of an observatory: long-term monitoring of precipital water vapour (PWV) is useful for characterizing potential observatory sites, and real-time monitoring of PWV is useful for optimizing use, in particular for mid-IR observations.
We present results of a project aimed at establishing a set of 12 spectro-photometric standards over a wide wavelength range from 320 to 2500 nm. Currently no such set of standard stars covering the near-IR is available. Our strategy is to extend the useful range of existing well-established optical flux standards (Oke 1990, Hamuy et al. 1992, 1994) into the near-IR by means of integral field spectroscopy with SINFONI at the VLT combined with state-of-the-art white dwarf stellar atmospheric models (TMAP, Holberg et al. 2008). As a solid reference, we use two primary HST standard white dwarfs GD71 and GD153 and one HST secondary standard BD+17 4708. The data were collected through an ESO “Observatory Programme” over ~40 nights between February 2007 and September 2008.
Infrared astronomy has come into its own over the last decade. Based on mature detector technology and sophisticated instrumentation it is contributing exciting science in many fields of astrophysics. Stellar evolution is a field that has long been dominated by ultraviolet and optical work, but one that has benefited from a strongly increasing contribution from the infrared (IR) and sub-millimeter (sub-mm) domains. In particular, spectroscopy in these domains holds the promise to enable important advances through quantitative analysis of individual stars and stellar systems.
A few star clusters in the Magellanic Clouds exhibit composite structures in the red-clump region of their colour–magnitude diagrams. The most striking case is NGC 419 in the Small Magellanic Cloud (SMC), where the red clump is composed of a main blob as well as a distinct secondary feature. This structure is demonstrated to be real and corresponds to the simultaneous presence of stars which passed through electron degeneracy after central-hydrogen exhaustion and those that did not. This rare occurrence in a single cluster allows us to set stringent constraints on its age and on the efficiency of convective-core overshooting during main-sequence evolution. We present a more detailed analysis of NGC 419, together with a first look at other populous Large Magellanic Cloud clusters which are apparently in the same phase: NGC 1751, NGC 1783, NGC 1806, NGC 1846, NGC 1852 and NGC 1917. We also compare these Magellanic Cloud cases with their Galactic counterparts, NGC 752 and NGC 7789. We emphasise the extraordinary potential of these clusters as absolute calibration marks on the age scale of stellar populations.
Open cluster remnants (OCRs) are fundamental objects to investigate open cluster dissolution processes (e.g., Bica et al. 2001; Carraro 2002; Pavani et al. 2003; Carraro et al. 2007; Pavani & Bica 2007). They are defined as poorly populated concentrations of stars, with enough members to show evolutionary sequences in colour–magnitude diagrams (CMDs) as a result of the dynamical evolution of an initially more massive physical system. An OCR is intrinsically poorly populated, which makes its differentiation from field-star fluctuations difficult. Among the possible approaches to establish the nature of OCRs, we adopted CMD analysis combined with a robust statistical tool applied to 2mass data. In addition, photometry is the main information source available for possible OCRs (POCRs). We developed a statistical diagnostic tool to analyse the CMDs of POCRs and verify them as physical systems, explore membership probabilityies taking into account field contamination and derive age, distance and reddening values in a self-consistent way. We present the results of our analysis of 88 POCRs that are part of a larger sample that is widely distributed across the sky, with a significant density contrast of bright stars compared to the Galactic field. The 88 objects are projected onto low-density Galactic fields, at relatively high latitudes (|b| > 15°). Studies of larger POCR samples will provide a better understanding of OCR properties and constraints for theoretical models, including new insights into the evolution of open clusters and their dissolution rates. The results of this ongoing survey will provide a general picture of these fossil stellar systems and their connection to Galactic-disk evolution.
Analysis of integrated spectra of star clusters in the Magellanic Clouds can bring important information for studies on the chemical evolution of the Clouds. The aim of the present work is to derive ages and metallicities from integrated spectra of 15 star clusters in the Small Magellanic Cloud (SMC), some of them not studied so far. Making use of a full spectrum fitting technique, we compared the integrated spectra of the sample clusters to three different sets of single stellar population models available in the literature. We derived ages and metallicities for the sample clusters employing the codes STARLIGHT and ULySS. Out of the 15 clusters in our sample, 9 are old/intermediate age clusters and 6 are young clusters. We point out the results for the newly identified as old/intermediate age clusters HW1, NGC 152, Lindsay 3 and 11. We also confirm old ages for NGC 361, NGC 419 and Kron 3, and the oldest well-known SMC cluster NGC 121.
We give a rigorous definition of tropical fans (the ‘local building blocks for tropical varieties’) and their morphisms. For a morphism of tropical fans of the same dimension we show that the number of inverse images (counted with suitable tropical multiplicities) of a point in the target does not depend on the chosen point; a statement that can be viewed as one of the important first steps of tropical intersection theory. As an application we consider the moduli spaces of rational tropical curves (both abstract and in some ℝr) together with the evaluation and forgetful morphisms. Using our results this gives new, easy and unified proofs of various tropical independence statements, e.g. of the fact that the numbers of rational tropical curves (in any ℝr) through given points are independent of the points.
The LMC clusters with similar ages to the Milky Way open clusters are in general more metal-poor and more populous than the latter, being located close enough to allow their stellar content to be well resolved. Therefore, they are unique templates of simple stellar population (SSP), being crucial to calibrate models describing the integral light as well as to test the stellar evolution theory. With this in mind we analyzed HST/WFPC2 (V, B − V) colour-magnitude diagrams (CMDs) of 15 populous LMC clusters with ages between ~0.3 Gyr and ~4 Gyr using different stellar evolutionary models. Following the approach described by Kerber, Santiago & Brocato (2007), we determined accurate and self-consistent physical parameters (age, metallicity, distance modulus and reddening) for each cluster by comparing the observed CMDs with synthetic ones generated using isochrones from the PEL and BaSTI libraries. These determinations were made by means of simultaneous statistical comparison of the main-sequence fiducial line and the red clump position, offering objective and robust criteria to select the best models. We compared these results with the ones obtained by Kerber, Santiago & Brocato (2007) using the Padova isochrones. This revealed that there are significant trends in the physical parameters due to the choice of stellar evolutionary model and treatment of convective core overshooting. In general, models that incorporate overshooting presented more reliable results than those that do not. Furthermore, the Padova models fitted better the data than the PEL and BaSTI models. Comparisons with the results found in the literature demonstrated that our derived metallicities are in good agreement with the ones from the spectroscopy of red giants. We also confirmed that, independent of the adopted stellar evolutionary library, the recovered 3D distribution for these clusters is consistent with a thick disk roughly aligned with the LMC disk as defined by field stars. Finally, we also provide new estimates of distance modulus to the LMC center, that are marginally consistent with the canonical value of 18.50 mag.
Markets need a complex set of institutions in order to work properly. Within a state, the national legal order with its legal rules, courts, and enforcement agencies have the task of fulfilling this role. Besides safeguarding property rights, the national legal order encompasses (1) the facilitating of market transactions by offering enabling (facilitative) law (as legal standard solutions) and helping private parties to enforce contracts within the domain of freedom of contract, and (2) the regulation of market transactions for solving or mitigating market failures problems and achieving other policy objectives. A comparable consistent legal system is missing on the international level for ensuring the working of global markets and the governance of cross-border transactions. However, the dynamic process of globalization has brought about the development of a number of new institutional solutions for solving these problems. The most prominent issue is the regulation of international markets (“global governance”). This article, however, will focus on the evolution of institutions for the enforcement of contracts for cross-border transactions between firms. Although there have always been institutional solutions for the governance of cross-border contracts (lex mercatoria), in recent years, a number of new governance solutions for the enforcement of cross-border transactions have emerged (“transnational commercial law”). The increasing use of choice of law, private governance instead of private law (provided by states), and private arbitration instead of public courts are the most important characteristics of this development. This also includes hybrids as new combinations between private and public solutions for the governance of cross-border contracts. Therefore, the process of globalization is accompanied and enabled by a complex process of institutional evolution.