Human impact on limestone pavement

[cat] Els paviments calcaris de les Illes Britàniques forneixen interessants exemples de l’activitat humana com a agent de canvi geomorfològic. Aquest article contempla la historia de la influencia humana en els paviments calcaris, especialment a l’Anglaterra nord-occidental, examina danys recents, i discuteix les accions realitzades per protegir aquestes formes paisatgístiques tan belles corn fascinants. Han estat diverses les activitats que han afectat els paviments, i la importància de les activitats individuals ha canviat amb el temps. Darrerament la pressió s'ha incrementat i els organismes conservacionistes s'han interessat pel problema per tal de protegir els paviments de nous estralls. Durant els darrers 30 anys, molts pocs paviments calcaris de les Illes Britàniques han deixat d'esser afectats per agressions o alteracions, i alguns han patit molt seriosament.[eng] The limestone pavements of the British Isles provide an interesting example of human activity as an agent of geomorphological change. This paper looks at the history of human influences on limestone pavements, especially in northwestern England, examines recent damage, and discusses the actions being taken to protect these fascinating and beautiful landforms. The activities which have affected the pavements have been varied, and the importance of any individual activity has changed over time. In recent decades the pressures have increased and conservation bodies have become concerned with the problem in order to protect pavement sites from further damage. Very few pavement sites in the British Isles have been unaffected by damage or alteration in the past 30 years, and come have suffered very severely

Exploring the performance of thin-film superconducting multilayers as kinetic inductance detectors for low-frequency detection

We have solved numerically the diffusive Usadel equations that describe the spatially varying superconducting proximity effect in Ti-Al thin-film bi- and trilayers with thickness values that are suitable for kinetic inductance detectors (KIDs) to operate as photon detectors with detection thresholds in the frequency range of 50-90 GHz. Using Nam's extension of the Mattis-Bardeen calculation of the superconductor complex conductivity, we show how to calculate the surface impedance for the spatially varying case, and hence the surface impedance quality factor. In addition, we calculate energy-and spatially-averaged quasiparticle lifetimes at temperatures well-below the transition temperature and compare to calculation in Al. Our results for the pair-breaking threshold demonstrate differences between bilayers and trilayers with the same total film thicknesses. We also predict high quality factors and long multilayer-averaged quasiparticle recombination times compared to thin-film Al. Our calculations give a route for designing KIDs to operate in this scientifically-important frequency regime

An Empirical Analysis of a Model for Student Success using a Case Study Approach

Historically black colleges and universities (HBCUs) play a critical role in the national college completion agenda within the United States of America (U.S.). With high enrolments of minority, first-generation, and economically disadvantaged students, HBCUs serve as essential access points to higher education and the American dream. Given the high needs student population of HBCUs, these institutions can serve as national and international models for improving college completion and demonstrating efficacy in promoting access to higher education among students from diverse backgrounds