Estudio de laboratorio de la susceptibilidad a la corrosión intergranular del cinc y su relación con el contenido de aluminio

A method of test for determining the susceptibility of zinc to the intergranular corrosion was developped, considering that the action of water steam on zinc produces the mentioned type of corrosion. Local and foreing specimens have been studied. In the suscep- tibies specimens, the sign of intergranular corrosion, characterized by visual and micrographic observations, appears after 30 h exposition. Correlation between susceptibility and aluminium content was established: 0,005 $ of aluminium in laminated zinc was the maximum content in order to avoid corrosion.Se ideó un método de ensayo para, determinar la susceptibilidad del cinc a la corrosión intergranular, teniendo en cuenta que el ataque con vapor de agua provoca en el cinc ese tipo corrosión. Se ensayaron probetas de origen nacional y extranjero. En las muestras susceptibles,los signos, de corrosión intergranular — que fueron caracterizados mediante observaciones visuales y micrográficas -r aparecieron después de las 30, horas de exposición. Se estableció una correlación entre esa susceptibilidad y él contenido de aluminio, y se fijó como contenido máximo de aluminio en -cinc laminado el de 0,005 %

On Sturmian Graphs

In this paper we define Sturmian graphs and we prove that all of them have a certain ''''counting'''' property. We show deep connections between this counting property and two conjectures, by Moser and by Zaremba, on the continued fraction expansion of real numbers. These graphs turn out to be the underlying graphs of compact directed acyclic word graphs of central Sturmian words. In order to prove this result, we give a characterization of the maximal repeats of central Sturmian words. We show also that, in analogy with the case of Sturmian words, these graphs converge to infinite ones

Nivat's conjecture holds for sums of two periodic configurations

Nivat's conjecture is a long-standing open combinatorial problem. It concerns two-dimensional configurations, that is, maps $\mathbb Z^2 \rightarrow \mathcal A$ where $\mathcal A$ is a finite set of symbols. Such configurations are often understood as colorings of a two-dimensional square grid. Let $P_c(m,n)$ denote the number of distinct $m \times n$ block patterns occurring in a configuration $c$. Configurations satisfying $P_c(m,n) \leq mn$ for some $m,n \in \mathbb N$ are said to have low rectangular complexity. Nivat conjectured that such configurations are necessarily periodic. Recently, Kari and the author showed that low complexity configurations can be decomposed into a sum of periodic configurations. In this paper we show that if there are at most two components, Nivat's conjecture holds. As a corollary we obtain an alternative proof of a result of Cyr and Kra: If there exist $m,n \in \mathbb N$ such that $P_c(m,n) \leq mn/2$, then $c$ is periodic. The technique used in this paper combines the algebraic approach of Kari and the author with balanced sets of Cyr and Kra.Comment: Accepted for SOFSEM 2018. This version includes an appendix with proofs. 12 pages + references + appendi

Motherhood in academia : a novel dataset with an application to maternity leave uptake

Legislation over the past two decades enhanced the availability and quantity of statutory maternity leave in the United Kingdom. In high-skilled sectors, many employers top up this maternity leave in an effort to retain and develop the careers of women. As leave provision became more generous, debates emerged as to the role, if any, these enhanced benefits have in retaining women in high status occupation and facilitating their career growth. Further, individual situations and employment status may prevent women from taking advantage of enhanced benefits. This paper presents findings from a comprehensive survey of thousands of women in the UK Higher Education sector and documents how the lives of academic mothers changed over the past quarter century. Contract status and the partner’s participation in parenting has significant effects on the types of maternity leave taken. We reflect on these findings and discuss future research in the area of labour market equity and productivity the availability of this comprehensive quantitative survey of academic women can facilitate

The motherhood penalties : insights from women in UK academia

We use an original survey of academic women in the UK to investigate different dimensions of the motherhood penalty. Being a mother has no effect on salaries, but still slows down career progression even in such a high-skilled sector. Motherhood has an ambivalent impact on women’s perception of their working environment: improving satisfaction, but reducing perception of salary fairness relative to men. Our paper also explores how different policies can mitigate the motherhood penalties. We find that more generous maternity provisions are associated with higher salary, potentially because generosity reduces the crowding out of research activity. Better availability of childcare and an even distribution of responsibilities within the household correlate positively with earnings. Our findings also highlight the importance of a supportive work environment for mothers’ career and well-being at the workplace. Taken together, these findings suggest the necessity of a multi-faceted policy response to the motherhood penalties

Leaf Growth and Canopy Development of Three Sugarcane Genotypes under High Temperature Rainfed Conditions in Northeastern Mexico

The aim of this study was to compare sugarcane (Saccharum spp.) canopy developmental components of three commercial varieties (CP 72-2086, Mex 79-431, and Mex 68-P-23) in a subtropical environment under rainfed and high temperature conditions, a poorly described topic in the literature. A field experiment was carried out in southern Tamaulipas, Mexico, throughout November 2011–January 2013 crop cycle, during which 111 of the days had daily maximum temperatures at or above 35°C. Number of leaves, leaf area, leaf appearance rate, and leaf area index (LAI) were determined. Thermal time exposure, °Cd (°C day−1), was determined based on total number of green ligulate leaves using 10°C as the base temperature. At 5000°Cd the number of leaves per plant ranged from 32 to 40 and the dependence of leaf emergence rate as a function of temperature was confirmed. The leaf emergence rate of CP 72-2086 was significantly greater than that of the other two varieties. Cultivars did not differ with respect to leaf length but differed for all other parameters measured. These results show the potential importance of considering sugarcane varietal differences in leaf phenology and canopy development for breeding programs focusing on rainfed and high temperature conditions

Separation Assurance and Scheduling Coordination in the Arrival Environment

Separation assurance (SA) automation has been proposed as either a ground-based or airborne paradigm. The arrival environment is complex because aircraft are being sequenced and spaced to the arrival fix. This paper examines the effect of the allocation of the SA and scheduling functions on the performance of the system. Two coordination configurations between an SA and an arrival management system are tested using both ground and airborne implementations. All configurations have a conflict detection and resolution (CD&R) system and either an integrated or separated scheduler. Performance metrics are presented for the ground and airborne systems based on arrival traffic headed to Dallas/ Fort Worth International airport. The total delay, time-spacing conformance, and schedule conformance are used to measure efficiency. The goal of the analysis is to use the metrics to identify performance differences between the configurations that are based on different function allocations. A surveillance range limitation of 100 nmi and a time delay for sharing updated trajectory intent of 30 seconds were implemented for the airborne system. Overall, these results indicate that the surveillance range and the sharing of trajectories and aircraft schedules are important factors in determining the efficiency of an airborne arrival management system. These parameters are not relevant to the ground-based system as modeled for this study because it has instantaneous access to all aircraft trajectories and intent. Creating a schedule external to the CD&R and the scheduling conformance system was seen to reduce total delays for the airborne system, and had a minor effect on the ground-based system. The effect of an external scheduler on other metrics was mixed

Nest-site fidelity in parental male bluegill Lepomis macrochirus: spatial patterns and the influence of prior mating success

A 4 year mark-recapture study examined the pattern of nesting site fidelity of parental-type male bluegill Lepomis macrochirus. The study results indicated that iteroparous male L. macrochirus choose new nest sites near their own previously used sites. The scale of site fidelity varied, but generally males choose to renest within shoreline areas rather than specific or exact nest locations (94% within-year, 86% among-years). Iteroparous males also displayed no preference to nest in proximity to neighbouring males from previous colonies to suggest social fidelity. Contrary to expectation, manipulating males' reproductive success had no significant effect on the pattern or scale of male reproductive site fidelity

Contrasting Styles of Inter-Caldera Volcanism in a Peralkaline System: Case Studies from Pantelleria (Sicily Channel, Italy)

The recent (\u3c190 ka) volcanic history of Pantelleria is characterized by the eruption of nine peralkaline ignimbrites, ranging in composition from comenditic trachyte to comendite to pantellerite. The ~46 ka Green Tuff (GT) was the last of these ignimbrites, which was followed by many effusive and explosive low-volume eruptions of pantellerite from vents within the caldera moat and along the caldera rim. Although recent studies have shed additional light on the age, petrochemistry, and volcanology of the older ignimbrites, there is very little knowledge of magmatism that occurred between these older ignimbrites, primarily due to the very scarce exposures. In this paper, we present new field descriptions and geochemical data for three local peralkaline centers never studied before, two pre-GT and one post-GT, which share a similar setting with respect to the caldera scarps but differ in terms of their age, composition, and eruptive style. These centers include: (i) the older (~125 ka) Giache center (comenditic trachyte), (ii) the ~67 ka Attalora center (comendite, pantellerite), and (iii) the younger (~14 ka) Patite center (pantellerite)

Protección de superficies metálicas

Índice general Capítulo I: Propiedades generales de las pinturas, por el Dr. Walter 0. Bruzzoni Capítulo II: Aceites y resinas formadoras de película, por el Dr. Vicente J. D. Rascio Capítulo III: PIinturas anticorrosivas, por el Dr. Vicente J. D. Rascio Capítulo IV: Caracteristicas de la superficie metálica. Métodos de preparación y tratamiento. Control de los recubrimientos en servicio. por el Dr. Vicente J. D. Rascio Capítulo V: Las incrustaciones biológicas ( Fouling ) por el Lic. Ricardo Bastida Capítulo VI: Protección antiincrustante de cascos de barcos por el Dr. Vicente J. D. Rascio Capítulo VII Control de calidad de pinturas, por el Dr. Walter 0. Bruzzoni Capítulo VIII Protección catódica en medio marino, por el Dr. Epifanio Rozad