Investigation of hybridized polyurethane, glass fibre reinforced cement and steel laminate in structural floor plate systems

Sandwich components have emerged as light weight, efficient, economical, recyclable and reusable building systems which provide an alternative to both stiffened steel and reinforced concrete. These components are made of composite materials in which two metal face plates or Glassfibre Reinforced Cement (GRC) layers are bonded and form a sandwich with light weight compact polyurethane (PU) elastomer core. Existing examples of product applications are light weight sandwich panels for walls and roofs, Sandwich Plate System (SPS) for stadia, arena terraces, naval construction and bridges and Domeshell structures for dome type structures. Limited research has been conducted to investigate performance characteristics and applicability of sandwich or hybrid materials as structural flooring systems. Performance characteristics of Hybrid Floor Plate Systems comprising GRC, PU and Steel have not been adequately investigated and quantified. Therefore there is very little knowledge and design guidance for their application in commercial and residential buildings. This research investigates performance characteristics steel, PU and GRC in Hybrid Floor Plate Systems (HFPS) and develops a new floor system with appropriate design guide lines

Bellan-bandi Palassa, Sri Lanka: Formation processes of a Mesolithic open-air site identified through thin section micromorphology

The streamside site of Bellan-bandi Pallassa, with the richest skeletal record of terminal Pleistocene-early Holocene hunter-gatherers on the island, is one of the most important prehistoric sites in Sri Lanka. We use thin section micromorphology of two samples from terminal Pleistocene (ca. 11,150-12,250 years BP) levels to infer processes of sediment accumulation and post-depositional change that led to the formation of the archaeological site. Charcoal and bone fragment-bearing gravely silty sand accumulated from a combination of colluvial, with possible contribution of aeolian, and anthropogenic processes, including combustion and associated bone-splintering activities. Some degree of reworking of bone and charcoal by slope wash processes and sediment fauna is evident. Post-depositional processes included incipient bone dissolution and calcrete formation in the vadose zone, probably reflecting wet/dry climatic seasonality in the early Holocene, and pervasive iron / manganese impregnation and rare vivianite authigenesis, reflecting later water-logging as a result of more humid phases in the Holocene and / or construction of a water tank above the site in historical times (probably 4th century CE). Our findings are consistent with the current interpretation of the site as a hunter-gatherer campsite, reflecting successful hunting adaptation to seasonally wet and dry conditions

AFRP retrofit of reinforced concrete columns against impact loading

Structures can be exposed to impact loads as a result of an explosion, falling objects, projectiles and vehicle collisions. Within the increasing threat of these impact sources, it is very important to protect the columns that are the vital members of the structural systems to ensure structural and personal safety. This study focuses on the performance of axially loaded reinforced concrete members subjected to impact loading. A dropped-weight test set-up developed to perform impact tests on reinforced concrete members. The test set-up was used to perform low elevation impact tests on reinforced concrete (RC) columns that targets to simulate vehicular impact against ground floor columns of low-rise buildings. Since, there is limited information about the transverse impact performances of RC columns; the main objective of this research is to assess the vulnerability of RC columns under transverse impact loads and to enhance their performances by using Aramid Fiber Reinforced Polymer (AFRP) sheets. The scope is limited to 300 mm square columns with 3 m height in low to medium rise buildings which were found to be more vulnerable to lateral impacts according to previous research conducted by the authors, (Gurbuz et al. 2010, 2011). This research provides fundamental knowledge on the behavior of RC columns under low elevation impact loading and also generates new information on impact strengthening of vulnerable concrete columns by AFRP sheets

Estudio para el monitoreo y evaluación del proyecto bosques, paisajes y medios de vida sostenibles (LLS-UICN) en la microcuenca esquichá y asistenica técnica agrícola a la Comunidad San Pablo Tacaná, Departamento de San Marcos

El presente trabajo de investigación se realizó en la microcuenca Esquichá, del municipio de Tacaná, del departamento de San Marcos. A través del monitorear se pudo conocer la situación actual de la microcuenca Esquichá, se elaboró una línea base con una serie de indicadores con énfasis en aspectos naturales y socioeconómicos de los pobladores de las comunidades. Dicho diagnóstico sirvió para determinar los problemas más notorios que estaban afectando la productividad de cultivos principalmente de tomate, cebolla y rosas. Así también se realizaron varios servicios en la comunidad, entre los que se destacan: la asistencia técnica en los cultivos mencionados, la construcción de un invernadero para el grupo de señoras de la cooperativa el intercambio entre la Asociación de Floricultores de San Juan Sacatepéquez (ASOFLORSA), Guatemala, con los trabajadores de la cooperativa “Unión y Progreso”. R. L. Esta última actividad representa una oportunidad para mejorar la producción de rosas en la comunidad, ya que por medio de ésta gira se conoció básicamente el manejo adecuado del cultivo y representa una oportunidad para mejorar las condiciones actuales. En síntesis, los principales aportes de este trabajo de graduación, muestran que las iniciativas para mejorar el manejo integral de las microcuencas, deben incluir acciones para fortalecer los sistemas de producción agrícola, con lo cual también se favorece el desarrollo de las comunidades rurales del país

Microliths in the South Asian rainforest ~45-4 ka: New insights from Fa-Hien Lena Cave, Sri Lanka

Microliths–small, retouched, often-backed stone tools–are often interpreted to be the product of composite tools, including projectile weapons, and efficient hunting strategies by modern humans. In Europe and Africa these lithic toolkits are linked to hunting of medium- and large-sized game found in grassland or woodland settings, or as adaptations to risky environments during periods of climatic change. Here, we report on a recently excavated lithic assemblage from the Late Pleistocene cave site of Fa-Hien Lena in the tropical evergreen rainforest of Sri Lanka. Our analyses demonstrate that Fa-Hien Lena represents the earliest microlith assemblage in South Asia (c. 48,000–45,000 cal. years BP) in firm association with evidence for the procurement of small to medium size arboreal prey and rainforest plants. Moreover, our data highlight that the lithic technology of Fa-Hien Lena changed little over the long span of human occupation (c. 48,000–45,000 cal. years BP to c. 4,000 cal. years BP) indicating a successful, stable technological adaptation to the tropics. We argue that microlith assemblages were an important part of the environmental plasticity that enabled Homo sapiens to colonise and specialise in a diversity of ecological settings during its expansion within and beyond Africa. The proliferation of diverse microlithic technologies across Eurasia c. 48–45 ka was part of a flexible human ‘toolkit’ that assisted our species’ spread into all of the world’s environments, and the development of specialised technological and cultural approaches to novel ecological situations

Specialized rainforest hunting by Homo sapiens ~45,000 years ago

Defining the distinctive capacities of Homo sapiens relative to other hominins is a major focus for human evolutionary studies. It has been argued that the procurement of small, difficult-to-catch, agile prey is a hallmark of complex behavior unique to our species; however, most research in this regard has been limited to the last 20,000 years in Europe and the Levant. Here, we present detailed faunal assemblage and taphonomic data from Fa-Hien Lena Cave in Sri Lanka that demonstrates specialized, sophisticated hunting of semi-arboreal and arboreal monkey and squirrel populations from ca. 45,000 years ago, in a tropical rainforest environment. Facilitated by complex osseous and microlithic technologies, we argue these data highlight that the early capture of small, elusive mammals was part of the plastic behavior of Homo sapiens that allowed it to rapidly colonize a series of extreme environments that were apparently untouched by its hominin relatives

Palaeogenomic analysis of black rat (Rattus rattus) reveals multiple European introductions associated with human economic history

The distribution of the black rat (Rattus rattus) has been heavily influenced by its association with humans. The dispersal history of this non-native commensal rodent across Europe, however, remains poorly understood, and different introductions may have occurred during the Roman and medieval periods. Here, in order to reconstruct the population history of European black rats, we first generate a de novo genome assembly of the black rat. We then sequence 67 ancient and three modern black rat mitogenomes, and 36 ancient and three modern nuclear genomes from archaeological sites spanning the 1st-17th centuries CE in Europe and North Africa. Analyses of our newly reported sequences, together with published mitochondrial DNA sequences, confirm that black rats were introduced into the Mediterranean and Europe from Southwest Asia. Genomic analyses of the ancient rats reveal a population turnover in temperate Europe between the 6th and 10th centuries CE, coincident with an archaeologically attested decline in the black rat population. The near disappearance and re-emergence of black rats in Europe may have been the result of the breakdown of the Roman Empire, the First Plague Pandemic, and/or post-Roman climatic cooling.Peer reviewe