Long-term and recent changes in sea level in the Falkland Islands

Mean sea level measurements made at Port Louis in the Falkland Islands in 1981-2, 1984 and 2009, together with values from the nearby permanent tide gauge at Port Stanley, have been compared to measurements made at Port Louis in 1842 by James Clark Ross. The long-term rate of change of sea level is estimated to have been +0.75 ± 0.35 mm/year between 1842 and the early 1980s, after correction for air pressure effects and for vertical land movement due to Glacial Isostatic Adjustment (GIA). The 2009 Port Louis data set is of particular importance due to the availability of simultaneous information from Port Stanley. The data set has been employed in two ways, by providing a short recent estimate of mean sea level itself, and by enabling the effective combination of measurements at the two sites. The rate of sea level rise observed since 1992, when the modern Stanley gauge was installed, has been larger at 2.51 ± 0.58 mm/year, after correction for air pressure and GIA. This rate compares to a value of 2.79 ± 0.42 mm/year obtained from satellite altimetry in the region over the same period. Such a relatively recent acceleration in the rate of sea level rise is consistent with findings from other locations in the southern hemisphere and globall

Chain Homotopies for Object Topological Representations

This paper presents a set of tools to compute topological information of simplicial complexes, tools that are applicable to extract topological information from digital pictures. A simplicial complex is encoded in a (non-unique) algebraic-topological format called AM-model. An AM-model for a given object K is determined by a concrete chain homotopy and it provides, in particular, integer (co)homology generators of K and representative (co)cycles of these generators. An algorithm for computing an AM-model and the cohomological invariant HB1 (derived from the rank of the cohomology ring) with integer coefficients for a finite simplicial complex in any dimension is designed here. A concept of generators which are "nicely" representative cycles is also presented. Moreover, we extend the definition of AM-models to 3D binary digital images and we design algorithms to update the AM-model information after voxel set operations (union, intersection, difference and inverse)

Effect of thermal exposure, forming, and welding on high-temperature, dispersion-strengthened aluminum alloy: Al-8Fe-1V-2Si

The feasibility of applying conventional hot forming and welding methods to high temperature aluminum alloy, Al-8Fe-1V-2Si (FVS812), for structural applications and the effect of thermal exposure on mechanical properties were determined. FVS812 (AA8009) sheet exhibited good hot forming and resistance welding characteristics. It was brake formed to 90 deg bends (0.5T bend radius) at temperatures greater than or equal to 390 C (730 F), indicating the feasibility of fabricating basic shapes, such as angles and zees. Hot forming of simple contoured-flanged parts was demonstrated. Resistance spot welds with good static and fatigue strength at room and elevated temperatures were readily produced. Extended vacuum degassing during billet fabrication reduced porosity in fusion and resistance welds. However, electron beam welding was not possible because of extreme degassing during welding, and gas-tungsten-arc welds were not acceptable because of severely degraded mechanical properties. The FVS812 alloy exhibited excellent high temperature strength stability after thermal exposures up to 315 C (600 F) for 1000 h. Extended billet degassing appeared to generally improve tensile ductility, fatigue strength, and notch toughness. But the effects of billet degassing and thermal exposure on properties need to be further clarified. The manufacture of zee-stiffened, riveted, and resistance-spot-welded compression panels was demonstrated

Race-Conscious Affirmative Action: What's Next

An expected national ban on the consideration of race in college admissions will threaten the racial and ethnic diversity of students at selective colleges unless these colleges fundamentally alter their admissions practices. Race-Conscious Affirmative Action: What's Next finds that selective colleges barred from considering race and ethnicity in their admissions decisions may be able to partially claw back some racial/ethnic diversity using class-conscious admissions practices, but they will be extremely unlikely to enroll student bodies that come close to mirroring the demographic diversity of the high school class

If Not Now, When? The Urgent Need for an All-One-System Approach to Youth Policy

This report makes the case that the United States' disjointed approach to youth policy has failed young people. In the current fragmented system, pre-K–12, postsecondary education, and the workforce operate in silos that allow many young people to fall through the cracks. In its place, the country needs an all-one-system approach that supports youth on their journey through education and training and into careers

Youth Policy: How Can We Smooth the Rocky Pathway to Adulthood?

While boosts in labor demand have helped young workers as the economy recovers from the COVID-19 recession, young people continue to grapple with a youth labor market that has been deteriorating for 20 years. Their prospects have been dimmed by three major recessions: the burst of the dot-com bubble (2001), the Great Recession (2007-2009), and the COVID-19 recession (2020). Further, long-term structural changes in the economy have favored older workers with more experience, training, and education while limiting opportunity for young workers.Youth Policy: How Can We Smooth the Rocky Pathway to Adulthood? examines the United States' fragmented and inadequate approach to youth policy against the backdrop of these economic pressures and recommends changes necessary to move toward a more comprehensive and holistic approach

A Tool for Integer Homology Computation: Lambda-At Model

In this paper, we formalize the notion of lambda-AT-model (where $\lambda$ is a non-null integer) for a given chain complex, which allows the computation of homological information in the integer domain avoiding using the Smith Normal Form of the boundary matrices. We present an algorithm for computing such a model, obtaining Betti numbers, the prime numbers p involved in the invariant factors of the torsion subgroup of homology, the amount of invariant factors that are a power of p and a set of representative cycles of generators of homology mod p, for each p. Moreover, we establish the minimum valid lambda for such a construction, what cuts down the computational costs related to the torsion subgroup. The tools described here are useful to determine topological information of nD structured objects such as simplicial, cubical or simploidal complexes and are applicable to extract such an information from digital pictures.Comment: Journal Image and Vision Computing, Volume 27 Issue 7, June, 200

Workplace Basics: The Competencies Employers Want 2020

Workers need more than just their educational credentials to qualify for jobs that pay well, keep those jobs, secure promotions, and boost their earnings on the job. Workplace Basics: The Competencies Employers Want reveals the five most in-demand competencies across the labor market