The evaluation of an activated sludge process at elevated temperatures

The feasibility of utilizing the thermal energy from an electric power plant to operate an activated sludge process at elevated temperatures (above 40°C) was assessed. The practicality of using this heat was determined from a heat transfer analysis and the operation of the activated sludge process was evaluated from laboratory studies of a batch process treating domestic and synthetic sewage. The tank size for a thermophilic activated sludge chamber could be reduced by 40 to 50% as compared to ambient temperatures. For thermophilic processes a temperature of 55°C is recommended because the transition phase between mesophiles and thermophiles is around 45°C and maximum growth rate occurs at 55°C. The effluent suspended solids after an hour and a half of settling was about 25 mg/1. Only about 10% of the thermal energy in the power plant cooling water is utilizable for increasing sewage temperatures to the thermophilic range. The additional boiler steam output required would be 7 to 33% for sewage flow rates of 20 to 100 MGD. The basic proposal described above was found to be technically feasible but the economic analysis was considered to be beyond the scope of this research. It was felt that such a proposal has application but additional research is needed --Abstract, page ii

Discovery of a Color-Selected Quasar at z=5.50

We present observations of RD J030117+002025, a quasar at z=5.50 discovered from deep, multi-color, ground-based observations covering 74 square arcmin. This is the most distant quasar or AGN currently known. The object was targeted as an R-band dropout, with R(AB)>26.3 (3-sigma limit in a 3 arcsec diameter region), I(AB)=23.8, and z(AB)=23.4. The Keck/LRIS spectrum shows broad Lyman-alpha/NV emission and sharp absorption decrements from the highly-redshifted hydrogen forests. The fractional continuum depression due to the Lyman-alpha forest is D(A)=0.90. RD J030117+002025 is the least luminous, high-redshift quasar known (M(B)~-22.7).Comment: 9 pages, 2 figures; to appear in the The Astrophysical Journal Letter

Optical Tweezers as an Effective Tool for Spermatozoa Isolation from Mixed Forensic Samples

A single focus optical tweezer is formed when a laser beam is launched through a high numerical aperture immersion objective. This objective focuses the beam down to a diffraction-limited spot, which creates an optical trap where cells suspended in aqueous solutions can be held fixed. Spermatozoa, an often probative cell type in forensic investigations, can be captured inside this optical trap and dragged one by one across millimeter-length distances in order to create a cluster of cells which can be subsequently drawn up into a capillary for collection. Sperm cells are then ejected onto a sterile cover slip, counted, and transferred to a tube for DNA analysis workflow. The objective of this research was to optimize sperm cell collection for maximum DNA yield, and to determine the number of trapped sperm cells necessary to produce a full STR profile. A varying number of sperm cells from both a single-source semen sample and a mock sexual assault sample were isolated utilizing optical tweezers and processed using conventional STR analysis methods. Results demonstrated that approximately 50 trapped spermatozoa were required to obtain a consistently full DNA profile. A complete, single-source DNA profile was also achieved by isolating sperm cells via optical trapping from a mixture of sperm and vaginal epithelial cells. Based on these results, optical tweezers are a viable option for forensic applications such as separation of mixed populations of cells in forensic evidence

Archaeological Investigations at the Ikirahak Site Raise Questions Concerning Taltheilei Land Use in Southern Nunavut

We report a new Taltheilei site-type found off the west coast of Hudson Bay in southern Nunavut. The Taltheilei is an archaeological culture that existed in the Barrenlands of the central Canadian Subarctic between 2600 and 300 years ago. Their land use strategies were tethered to the seasonal migrations of the Beverly and Qamanirjuaq caribou herds throughout tundra and forest landscapes. Tundra-based sites are typically interpreted as short-lived summer camps, but our discovery of three unique pit-house sites on the shores of Maguse Lake raises new questions concerning diversity in Taltheilei tundra land use. Architectural, faunal, lithic, and geoarchaeological data recovered from the Ikirahak site (JjKs-7) support the hypothesis that Taltheilei groups were extending their tundra stays into the fall. We report the evidence from four excavated pit-house features. Terraced platforms along the internal perimeters of these houses suggest they were designed for cold season use. The faunal assemblage is dominated by caribou remains. Higher relative frequencies of appendicular elements suggest a focus on secondary butchering. A large fraction of the faunal assemblage is highly fragmented and calcined, which is consistent with heavy processing and the use of bone as an alternative fuel source. Higher frequencies of lithic debris around dwelling floor perimeters are suggestive of maintenance activities. Multi-element concentrations in dwelling and site-wide sediments also show that hearth refuse was dumped outside. These findings seem to reflect longer tundra occupations during fall, a land use strategy that was likely guided by Qamanirjuaq herd behaviour specific to the Maguse Lake area, fall hunting and processing goals, and ecologically couched mobility logistics. As just four pit-houses from one Taltheilei camp have been investigated to date, our understanding of these places within Taltheilei worlds and northern socio-ecologies is currently limited. Further research at Ikirahak, the other Maguse Lake pit-house sites, and at other caribou water crossings on the tundra of the Qamanirjuaq caribou range is needed to support or refute our hypotheses.Nous signalons un nouveau site de type taltheilei trouvé sur la côte ouest de la baie d’Hudson, dans le sud du Nunavut. La culture taltheilei est une culture archéologique qui a existé dans les landes de la zone subarctique centrale canadienne il y a de cela 2600 à 300 ans. Les stratégies d’utilisation des terres de cette culture étaient rattachées aux migrations saisonnières des hardes de caribous de Beverly et de Qamanirjuaq dans la toundra et la forêt. De manière générale, les sites trouvés dans la toundra sont interprétés comme des campements d’été de courte durée. Cependant, notre découverte de trois sites uniques de maisons semi-souterraines sur les rives du lac Maguse soulève de nouvelles questions au sujet de la diversité de l’utilisation de la toundra par les Taltheilei. Les données architecturales, fauniques, lithiques et géoarchéologiques recueillies au site d’Ikirahak soutiennent l’hypothèse selon laquelle les groupements de Taltheilei occupaient la toundra jusqu’à l’automne. Nous signalons des preuves en provenance de quatre aménagements de maisons semi-souterraines. Le long du périmètre interne de ces maisons, les plateformes en terrasses suggèrent qu’elles étaient conçues pour servir pendant la saison froide. Des restes de caribous dominent l’assemblage faunique. Des fréquences relatives plus élevées d’éléments appendiculaires laissent entrevoir que le dépeçage secondaire y occupait une grande place. Une grande fraction de l’assemblage faunique est fortement fragmentée et calcinée, ce qui correspond à une transformation importante et à l’utilisation des os comme source de combustible. Les grandes fréquences de débris lithiques entourant le périmètre des planchers d’habitations suggèrent des activités de maintenance. Les concentrations d’éléments multiples dans les sédiments des habitations et de l’ensemble du site indiquent également que les déchets des âtres étaient jetés à l’extérieur. Ces constatations laissent entrevoir de plus longues occupations de la toundra à l’automne, une stratégie d’utilisation des terres vraisemblablement guidée par le comportement propre à la harde de Qamanirjuaq dans la région du lac Maguse, par la chasse automnale et par les objectifs de transformation, de même que par la logistique de la mobilité en termes écologiques. Puisque seulement quatre maisons semi-souterraines d’un seul campement taltheilei ont été étudiées jusqu’à maintenant, nous comprenons toujours peu de choses au sujet de ces endroits dans le monde des Taltheilei et des socioécologies nordiques. Il y a lieu de pousser les recherches plus loin à Ikirahak, là où se trouvent les autres sites de maisons semi-souterraines du lac Maguse, ainsi qu’à d’autres passages de franchissement de l’eau sur la toundra du parcours des caribous de Qamanirjuaq afin de confirmer ou de réfuter nos hypothèses

Heat Conduction and Entropy Production in a One-Dimensional Hard-Particle Gas

We present large scale simulations for a one-dimensional chain of hard-point particles with alternating masses. We correct several claims in the recent literature based on much smaller simulations. Both for boundary conditions with two heat baths at different temperatures at both ends and from heat current autocorrelations in equilibrium we find heat conductivities kappa to diverge with the number N of particles. These depended very strongly on the mass ratios, and extrapolation to N -> infty resp. t -> infty is difficult due to very large finite-size and finite-time corrections. Nevertheless, our data seem compatible with a universal power law kappa ~ N^alpha with alpha approx 0.33. This suggests a relation to the Kardar-Parisi-Zhang model. We finally show that the hard-point gas with periodic boundary conditions is not chaotic in the usual sense and discuss why the system, when kept out of equilibrium, leads nevertheless to energy dissipation and entropy production.Comment: 4 pages (incl. 5 figures), RevTe

Identification of single-site gold catalysis in acetylene hydrochlorination

There remains considerable debate over the active form of gold under operating conditions of a recently validated gold catalyst for acetylene hydrochlorination. We have performed an in situ x-ray absorption fine structure study of gold/carbon (Au/C) catalysts under acetylene hydrochlorination reaction conditions and show that highly active catalysts comprise single-site cationic Au entities whose activity correlates with the ratio of Au(I):Au(III) present. We demonstrate that these Au/C catalysts are supported analogs of single-site homogeneous Au catalysts and propose a mechanism, supported by computational modeling, based on a redox couple of Au(I)-Au(III) species. View Full Tex

Epidemic predictions in an imperfect world : modelling disease spread with partial data

‘Big-data’ epidemic models are being increasingly used to influence government policy to help with control and eradication of infectious diseases. In the case of livestock, detailed movement records have been used to parametrize realistic transmission models. While livestock movement data are readily available in the UK and other countries in the EU, in many countries around the world, such detailed data are not available. By using a comprehensive database of the UK cattle trade network, we implement various sampling strategies to determine the quantity of network data required to give accurate epidemiological predictions. It is found that by targeting nodes with the highest number of movements, accurate predictions on the size and spatial spread of epidemics can be made. This work has implications for countries such as the USA, where access to data is limited, and developing countries that may lack the resources to collect a full dataset on livestock movements

Uncoupling clutch size, prolactin, and luteinizing hormone using experimental egg removal

Clutch size is a key avian fitness and life history trait. A physiological model for clutch size determination CSD), involving an anti-gonadal effect of prolactin (PRL) via suppression of luteinizing hormone (LH),was proposed over 20 years ago, but has received scant experimental attention since. The few studies looking at a PRL-based mechanistic hypothesis for CSD have been equivocal, but recent experiments utilizing a pharmacological agent to manipulate PRL in the zebra finch (Taeniopygia guttata) found no support for a role of this hormone in clutch size determination. Here, we take a complementary approach by manipulating clutch size through egg removal, examining co-variation in PRL and LH between two breeding attempts, as well as through experimentally-extended laying. Clutch size increased for egg removal females, but not controls, but this was not correlated with changes in PRL or LH. There were also no differences in PRL between egg removal females and controls, nor did PRL levels during early, mid- or late-laying of supra-normal clutches predict clutch size. By uncoupling PRL, LH and clutch size in our study, several key predictions of the PRL-based mechanistic model for CSD were not supported. However,a positive correlation between PRL levels late in laying and days relative to the last egg (clutch completion) provides an alternative explanation for the equivocal results surrounding the conventional PRL-based physiological model for CSD. We suggest that females coordinate PRL-mediated incubation onset with clutch completion to minimize hatching asynchrony and sibling hierarchy, a behavior that is amplified in females laying larger clutches