Response of the Arctic Pteropod Limacina helicina to projected future environmental conditions

Thecosome pteropods (pelagic mollusks) can play a key role in the food web of various marine ecosystems. They are a food source for zooplankton or higher predators such as fishes, whales and birds that is particularly important in high latitude areas. Since they harbor a highly soluble aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The effect of changes in the seawater chemistry was investigated on Limacina helicina, a key species of Arctic pelagic ecosystems. Individuals were kept in the laboratory under controlled pCO2 levels of 280, 380, 550, 760 and 1020 matm and at control (0uC) and elevated (4uC) temperatures. The respiration rate was unaffected by pCO2 at control temperature, but significantly increased as a function of the pCO2 level at elevated temperature. pCO2 had no effect on the gut clearance rate at either temperature. Precipitation of CaCO3, measured as the incorporation of 45Ca, significantly declined as a function of pCO2 at both temperatures. The decrease in calcium carbonate precipitation was highly correlated to the aragonite saturation state. Even though this study demonstrates that pteropods are able to precipitate calcium carbonate at low aragonite saturation state, the results support the current concern for the future of Arctic pteropods, as the production of their shell appears to be very sensitive to decreased pH. A decline of pteropod populations would likely cause dramatic changes to various pelagic ecosystems

Carn Goedog medieval house and settlement, Pembrokeshire

This report describes the investigation in 2011 and 2015 of two groups of relict houses on an upland common on the north flank of the Preseli hills in North Pembrokeshire. Their locations, along with medieval records, provide strong indications that these were seasonal settlements. Excavation of one subrectangular building (House C) produced finds that included medieval pottery and a spindle whorl with Romanesque decoration. A radiocarbon date of cal. AD 1030–1200 at 95.4% confidence from charcoal in the hearth of this building provides the earliest firm date identified as yet for hafodydd (‘seasonal settlements’) in Wale

Coevolução de genética e sistemas de produção, para romper circulo vicioso no melhoramento vegetal.

Ver Memória do Evento em http://www.embrapa.br/eu_quero/inovaecri

Morphological indicators of growth response of coniferous advance regeneration to overstorey removal in the boreal forest

Regeneration of forest stands through the preservation of existing advance regeneration has gained considerable interest in various regions of North America. The effectiveness of this approach relies on the capacity of regeneration to respond positively to overstory removal. Responses of advance regeneration to release is dependent on tree characteristics and site conditions interacting with the degree of physiological shock caused by the sudden change in environmental conditions. This paper presents a review of the literature describing the relationships between morphological indicators and the advance regeneration response to canopy removal. It focuses primarily on the following species: jack pine (Pinus banksiana Lamb.), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), black spruce (Picea mariana (Mill.) B.S.P.), interior spruce (Picea glauca x engelmannii), white spruce (Picea glauca (Moench) Voss), balsam fir (Abies balsamea (L.) Mill.), and subalpine fir (Abies lasiocarpa (Hook.) Nutt). Pre-release height growth has been found to be a good indicator of post-release response for many species. Live-crown ratio also appears to be a good indicator of vigour for shade-tolerant species. The ratio of leader length to length of the longest lateral at the last whorl could serve to describe the degree of suppression before harvest for shade-tolerant species. Number of nodal and internodal branches or buds has been found to be related with vigour for many species. Logging damage has been shown to be an important determinant of seedling response to overstory removal. In contrast, height/diameter ratio has limited value for predicting response to release since it varies with site, species and other factors. No clear relationship between age, height at release and response to release could be demonstrated. This paper also suggests the use of combined indicators and critical threshold values for these indicators

Age-related Changes in geometric characteristics of the pediatric thoracic cage and comparison of thorax shape with a pediatric CPR manikin

Pediatric cardiopulmonary resuscitation (CPR) manikins are currently used as training devices to simulate resuscitation methods for treating pediatric cardiac arrest or airway obstructions. In order for these manikins to meet clinically regulated CPR delivery guidelines and to function as effective surrogates, pediatric CPR manikins should have geometric and mechanical characteristics that are similar to pediatric human subjects. The objectives of this study were to (1) quantify the detailed geometric characteristics of the pediatric thoracic cage by using computed tomography (CT) scans obtained from pediatric human subjects, and (2) to compare the thorax shape of a pediatric CPR manikin (Little Junior CPR manikin, Laerdal, Stavanger, Norway) with a six year old pediatric human subject. Thorax CT scans were obtained from one, three, six, 10 and 18 year old male subjects (5 subjects per age group). Anatomical landmarks on the thoracic cage, such as costochondral junction, tubercle, external surface of the rib shaft etc., were digitized and a custom MATLAB code was created to compute the geometrical characteristics based on the Cartesian coordinates of these points. The key computed parameters include rib length, rib angle, longitudinal twist of the ribs, and radius of curvature of the ribs. Age-specific differences were observed in the pediatric thoracic structure in many of the computed parameters. The comparison of the outer thorax surface of the pediatric CPR manikin and a six year old child was performed in ProEngineer (Parametric Technology Corporation, Santa Clara, CA). Differences were observed in the overall thorax shape between the pediatric CPR manikin and the pediatric human subject. These shape comparisons indicate a need to modify the design of the pediatric CPR manikin thorax to be more representative of the pediatric human thorax.M.S., Biomedical Engineering -- Drexel University, 201