Moisture susceptibility of high and low compaction dry process crumb rubber modified asphalt mixtures

The field performance of dry process crumb rubber-modified (CRM) asphalt mixtures has been reported to be inconsistent with stripping and premature cracking on the surfacing. One of the concerns is that, because achieving field compaction of CRM material is difficult due to the inherent resilient nature of the rubber particle, nonuniform field compaction may lead to a deficient bond between rubber and bitumen. To assess the influence of compaction, a series of CRM and control mixtures was produced and compacted at two levels: 4% (low, optimum laboratory compaction) and 8% (high, field experience) air void content. The long-term durability, in regard to moisture susceptibility of the mixtures, was assessed by conducting repeated moisture conditioning cycles. Mechanical properties (stiffness, fatigue, and resistance to permanent deformation) were determined in the Nottingham Asphalt Tester. Results indicated that compared with conventional mixtures, the CRM mixtures, regardless of compaction effort, are more susceptible to moisture with the degree of susceptibility primarily depending on the amount of rubber in the mixture, rather than the difference in compaction. This behavior is different from that of conventional mixtures in which, as expected, poorly compacted mixtures were found to be more susceptible to moisture than were well-compacted mixtures

Primer reporte de Candida auris en Perú

Candida auris is an emerging fungus that has gained great relevance as a global public health problem in a short time. The presence of Candida auris in 3 adult patients admitted to a national hospital of high complexity in the last quarter of 2020 in the midst of the COVID-19 pandemic is reported for the first time in Peru. The patients were hospitalized in the ICU, however, this germ was isolated in only 2 patients while they were hospitalized in the ICU. The patients had various comorbidities and long hospitalization times from admission to having their first culture positive for C. auris. All patients acquired a bacterial nosocomial infection at some point during their hospitalization and received broad-spectrum antibiotics. All isolates were resistant to Fluconazole. The hospital's infection control team reinforced containment measures and the Ministry of Health issued an epidemiological alert.Candida auris es un hongo emergente que ha cobrado en corto tiempo gran relevancia como problema de salud pública mundial. Se reporta por primera vez en el Perú la presencia de Candida auris en 3 pacientes adultos internados en un hospital nacional de alta complejidad en el último trimestre del año 2020 en plena pandemia de COVID-19.  Los pacientes fueron hospitalizados en UCI, sin embargo, solo en 2 pacientes se aisló dicho germen mientras estaban hospitalizados en UCI.  Los pacientes tenían varias comorbilidades y tiempos prolongados de hospitalización desde su admisión hasta tener su primer cultivo positivo a C. auris.  Todos los pacientes adquirieron una infección nosocomial bacteriana en algún momento de su hospitalización y recibieron antibióticos de amplio espectro. Todas las cepas aisladas eran resistentes a Fluconazol.  El equipo de control de infecciones del hospital reforzó las medidas de contención y el Ministerio de Salud emitió una alerta epidemiológica

Nonrenewable Resources, Strategic Behavior and the Hotelling Rule: An Experiment

This study uses the methods of experimental economics to investigate possible causes for the failure of the Hotelling rule for nonrenewable resources. We argue that as long as resource stocks are large enough, producers may choose to (partially) ignore the dynamic component of their production decision, shifting production to the present and focusing more on strategic behavior. We experimentally vary stock size in a nonrenewable resource duopoly setting and find that producers with large stocks indeed pay significantly less attention to variables related to dynamic optimization,leading to a failure of the Hotelling rule

Disequilibrium, adaptation and the Norse settlement of Greenland

This research was supported by the University of Edinburgh ExEDE Doctoral Training Studentship and NSF grant numbers 1202692 and 1140106.There is increasing evidence to suggest that arctic cultures and ecosystems have followed non-linear responses to climate change. Norse Scandinavian farmers introduced agriculture to sub-arctic Greenland in the late tenth century, creating synanthropic landscapes and utilising seasonally abundant marine and terrestrial resources. Using a niche-construction framework and data from recent survey work, studies of diet, and regional-scale climate proxies we examine the potential mismatch between this imported agricultural niche and the constraints of the environment from the tenth to the fifteenth centuries. We argue that landscape modification conformed the Norse to a Scandinavian style of agriculture throughout settlement, structuring and limiting the efficacy of seasonal hunting strategies. Recent climate data provide evidence of sustained cooling from the mid thirteenth century and climate variation from the early fifteenth century. Archaeological evidence suggests that the Norse made incremental adjustments to the changing sub-arctic environment, but were limited by cultural adaptations made in past environments.Publisher PDFPeer reviewe