435 research outputs found
Settlement Archaeology in the Jauja Region of Peru: Evidence from the Early Intermediate Period; A Report on the 1986 Field Season
Eukaryotic plankton communities across reef environments in Bocas del Toro Archipelago, Panamá
Variation in light and temperature can influence the genetic diversity and structure of marine plankton communities. While open-ocean plankton communities receive much scientific attention, little is known about how environmental variation affects plankton communities on tropical coral reefs. Here, we characterize eukaryotic plankton communities on coral reefs across the Bocas del Toro Archipelago, Panamá. Temperature loggers were deployed, and midday light levels were measured to quantify environmental differences across reefs at four inshore and four offshore sites (Inshore = Punta Donato, Smithsonian Tropical Research Institute (STRI) Point, Cristobal, Punta Laurel and Offshore = Drago Mar, Bastimentos North, Bastimentos South, and Cayo de Agua). Triplicate vertical plankton tows were collected midday, and high-throughput 18S ribosomal DNA metabarcoding was leveraged to investigate the relationship between eukaryotic plankton community structure and inshore/offshore reef environments. Plankton communities from STRI Point were additionally characterized in the morning (~ 08:00), midday (~ 12:00), and late-day (~ 16:00) to quantify temporal variation within a single site. We found that inshore reefs experienced higher average seawater temperatures, while offshore sites offered higher light levels, presumably associated with reduced water turbidity on reefs further from shore. These significant environmental differences between inshore and offshore reefs corresponded with overall plankton community differences. We also found that temporal variation played a structuring role within these plankton communities, and conclude that time of community sampling is an important consideration for future studies. Follow-up studies focusing on more intensive sampling efforts across space and time, coupled with techniques that can detect more subtle genetic differences between and within communities will more fully capture plankton dynamics in this region and beyond
Distribution modelling and statistical phylogeography: an integrative framework for generating and testing alternative biogeographical hypotheses
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73644/1/j.1365-2699.2007.01814.x.pd
Assessment of energy credits for the enhancement of the Egyptian Green Pyramid Rating System
Energy is one of the most important categories in the Green Building Rating Systems all over the world. Green Building is a building that meets the energy requirements of the present with low energy consumption and investment costs without infringing on the rights of forthcoming generations to find their own needs. Despite having more than a qualified rating system, it is clear that each system has different priorities and needs on the other. Accordingly, this paper proposes a methodology using the Analytic Hierarchy Process (AHP) for assessment of the energy credits through studying and comparing four of the common global rating systems, the British Building Research Establishment Environmental Assessment Method (BREEAM), the American Leadership in Energy and Environmental Design (LEED), the Australian Green Stars (GS), and the PEARL assessment system of the United Arab Emirates, in order to contribute to the enhancement of the Egyptian Green Pyramid Rating System (GPRS). The results show the mandatory and optional energy credits that should be considered with their proposed weights according to the present and future needs of green Egypt. The results are compared to data gathered through desk studies and results extracted from recent questionnaires
Generation of vortices and observation of Quantum Turbulence in an oscillating Bose-Einstein Condensate
We report on the experimental observation of vortex formation and production
of tangled vortex distribution in an atomic BEC of Rb-87 atoms submitted to an
external oscillatory perturbation. The oscillatory perturbations start by
exciting quadrupolar and scissors modes of the condensate. Then regular
vortices are observed finally evolving to a vortex tangle configuration. The
vortex tangle is a signature of the presence of a turbulent regime in the
cloud. We also show that this turbulent cloud has suppression of the aspect
ratio inversion typically observed in quantum degenerate bosonic gases during
free expansion.Comment: to appear in JLTP - QFS 200
Evolution of deformation and recrystallization textures in high-purity Ni and the Ni-5 at. pct W alloy
An attempt has been made to study the evolution of texture in high-purity Ni and Ni-5 at. pct W alloy prepared by the powder metallurgy route followed by heavy cold rolling (∼95 pct deformation) and recrystallization. The deformation textures of the two materials are of typical pure metal or Cu-type texture. Cube-oriented ({001} {100}) regions are present in the deformed state as long thin bands, elongated in the rolling direction (RD). These bands are characterized by a high orientation gradient inside, which is a result of the rotation of the cube-oriented cells around the RD toward the RD-rotated cube ({013} {100}). Low-temperature annealing produces a weak cube texture along with the {013} {100} component, with the latter being much stronger in high-purity Ni than in the Ni-W alloy. At higher temperatures, the cube texture is strengthened considerably in the Ni-W alloy; however, the cube volume fraction in high-purity Ni is significantly lower because of the retention of the {013} {100} component. The difference in the relative strengths of the cube, and the {013} {100} components in the two materials is evident from the beginning of recrystallization in which more {013} {100} -oriented grains than near cube grains form in high-purity Ni. The preferential nucleation of the near cube and the {013} {100} grains in these materials seems to be a result of the high orientation gradients associated with the cube bands that offer a favorable environment for early nucleation
Phase Identification and Internal Stress Analysis of Steamside Oxides on Plant Exposed Superheater Tubes
The effects of viral load burden on pregnancy loss among HIV-infected women in the United States
Background. To evaluate the effects of HIV viral load, measured cross-sectionally and cumulatively, on the risk of miscarriage or stillbirth (pregnancy loss) among HIV-infected women enrolled in the Women's Interagency HIV Study between 1994 and 2013. Methods. We assessed three exposures: most recent viral load measure before the pregnancy ended, log10 copy-years viremia from initiation of antiretroviral therapy (ART) to conception, and log10 copy-years viremia in the two years before conception. Results. The risk of pregnancy loss for those with log10 viral load >4.00 before pregnancy ended was 1.59 (95% confidence interval (CI): 0.99, 2.56) times as high as the risk for women whose log10 viral load was ≤1.60. There was not a meaningful impact of log10 copy-years viremia since ART or log10 copy-years viremia in the two years before conception on pregnancy loss (adjusted risk ratios (aRRs): 0.80 (95% CI: 0.69, 0.92) and 1.00 (95% CI: 0.90, 1.11), resp.). Conclusions. Cumulative viral load burden does not appear to be an informative measure for pregnancy loss risk, but the extent of HIV replication during pregnancy, as represented by plasma HIV RNA viral load, predicted loss versus live birth in this ethnically diverse cohort of HIV-infected US women
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Compulsory licensing and access to drugs
Compulsory licensing allows the use of a patented invention without the owner's consent, with the aim of improving access to essential drugs. The pharmaceutical sector argues that, if broadly used, it can be detrimental to innovation. We model the interaction between a company in the North that holds the patent for a certain drug and a government in the South that needs to purchase it. We show that both access to drugs and pharmaceutical innovation depend largely on the Southern country's ability to manufacture a generic version. If the manufacturing cost is too high, compulsory licensing is not exercised. As the cost decreases, it becomes a credible threat forcing prices down, but reducing both access and innovation. When the cost is low enough, the South produces its own generic version and access reaches its highest value, despite a reduction in innovation. The global welfare analysis shows that the overall impact of compulsory licensing can be positive, even when accounting for its impact on innovation. We also consider the interaction between compulsory licensing and the strength of intellectual property rights, which can have global repercussions in other markets beyond the South
An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex
The North American Ice Sheet Complex (NAISC; consisting of the Laurentide, Cordilleran and Innuitian ice sheets) was the largest ice mass to repeatedly grow and decay in the Northern Hemisphere during the Quaternary. Understanding its pattern of retreat following the Last Glacial Maximum is critical for studying many facets of the Late Quaternary, including ice sheet behaviour, the evolution of Holocene landscapes, sea level, atmospheric circulation, and the peopling of the Americas. Currently, the most up-to-date and authoritative margin chronology for the entire ice sheet complex is featured in two publications (Geological Survey of Canada Open File 1574 [Dyke et al., 2003]; ‘Quaternary Glaciations – Extent and Chronology, Part II’ [Dyke, 2004]). These often-cited datasets track ice margin recession in 36 time slices spanning 18 ka to 1 ka (all ages in uncalibrated radiocarbon years) using a combination of geomorphology, stratigraphy and radiocarbon dating. However, by virtue of being over 15 years old, the ice margin chronology requires updating to reflect new work and important revisions. This paper updates the aforementioned 36 ice margin maps to reflect new data from regional studies. We also update the original radiocarbon dataset from the 2003/2004 papers with 1541 new ages to reflect work up to and including 2018. A major revision is made to the 18 ka ice margin, where Banks and Eglinton islands (once considered to be glacial refugia) are now shown to be fully glaciated. Our updated 18 ka ice sheet increased in areal extent from 17.81 to 18.37 million km2, which is an increase of 3.1% in spatial coverage of the NAISC at that time. Elsewhere, we also summarize, region-by-region, significant changes to the deglaciation sequence. This paper integrates new information provided by regional experts and radiocarbon data into the deglaciation sequence while maintaining consistency with the original ice margin positions of Dyke et al. (2003) and Dyke (2004) where new information is lacking; this is a pragmatic solution to satisfy the needs of a Quaternary research community that requires up-to-date knowledge of the pattern of ice margin recession of what was once the world’s largest ice mass. The 36 updated isochrones are available in PDF and shapefile format, together with a spreadsheet of the expanded radiocarbon dataset (n = 5195 ages) and estimates of uncertainty for each interval
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