174,777 research outputs found
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Palaeoenvironment of a mesolithic peat bed from Austin Friars, Leicester
A mesolithic peat bed, dated to 9920±100 bp (HAR-4260) (bp = radiocarbon years before the present calculated from A.D. 19S0 within + or - of 100 years in this case. Ed.) was recovered from Austin Friars, Leicester. Analysis of preserved fauna and flora, especially insects and seeds, indicated that the peat had formed in a shallow pond or lake, with vegetated, marshy edges subject to periodic flooding. The pond was set in open countryside characterised by a lack of trees and preponderance of light-demanding species, living in a cold, damp tundra climate at the very end of Late Glacial Zone III (9000-8300 RC.) extending into the Post Glacial (8300-4000 RC.)
Energy aspects and ventilation of food retail buildings
Worldwide the food system is responsible for 33% of greenhouse gas emissions. It is estimated that by 2050, the total food production should be 70% more than current food production levels. In the UK, food chain is responsible for around 18% of final energy use and 20% of GHG emissions. Estimates indicate that energy savings of the order of 50% are achievable in food chains by appropriate technology changes in food production, processing, packaging, transportation, and consumption. Ventilation and infiltration account for a significant percentage of the energy use in food retail (supermarkets) and catering facilities such as restaurants and drink outlets. In addition, environmental conditions to maintain indoor air quality and comfort for the users with minimum energy use for such buildings are of primary importance for the business owners and designers. In particular, supermarkets and restaurants present design and operational challenges because the heating ventilation and air-conditioning system has some unique and diverse conditions that it must handle. This paper presents current information on energy use in food retail and catering facilities and continues by focusing on the role of ventilation strategies in food retail supermarkets. It presents the results of current studies in the UK where operational low carbon supermarkets are predicted to save 66% of CO2 emissions compared to a base case store. It shows that low energy ventilation strategies ranging from improved envelope air-tightness, natural ventilation components, reduction of specific fan power, ventilative cooling, novel refrigeration systems using CO2 combined with ventilation heat recovery and storage with phase change materials can lead to significant savings with attractive investment return
Escape from immunotherapy: possible mechanisms that influence tumor regression/progression
Tumor escape is one major obstacle that has to be addressed prior to designing and delivering successful immunotherapy. There is compelling evidence to support the notion that immunogenic tumors, in murine models and cancer patients, can be rejected by the immune system under optimum conditions for activating adaptive and nonadaptive antitumor immune responses. Despite this capability, a large number of tumors continue to grow and evade recognition and/or destruction by the immune system. The limited success in current immunotherapeutic strategies may be due to a variety of reasons: failure of effector cells to compete with the growing tumor burden, production of humoral factors by tumors that locally block cytotoxicity, antigen/MHC loss, T-cell dysfunction, production of suppressor T cells—to name but a few causes for therapeutic ineffectiveness for the particular malignancy being treated. To optimize immunotherapy strategies, correction of immune-activating signals, eradication of inhibitory factors, and the evasion from newly developed immunoresistant tumor phenotypes need to be simultaneously considered
Cities: Continuity, transformation and emergence
Book synopsis: This book applies ideas and methods from the complexity perspective to key concerns in the social sciences, exploring co-evolutionary processes that have not yet been addressed in the technical or popular literature on complexity. \ud
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Authorities in a variety of fields – including evolutionary economics, innovation and regeneration studies, urban modelling and history – re-evaluate their disciplines within this framework. The book explores the complex dynamic processes that give rise to socio-economic change over space and time, with reference to empirical cases including the emergence of knowledge-intensive industries and decline of mature regions, the operation of innovative networks and the evolution of localities and cities. Sustainability is a persistent theme and the practicability of intervention is examined in the light of these perspectives. \ud
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Specialists in disciplines that include economics, evolutionary theory, innovation, industrial manufacturing, technology change, and archaeology will find much to interest them in this book. In addition, the strong interdisciplinary emphasis of the book will attract a non-specialist audience interested in keeping abreast of current theoretical and methodological approaches through evidence-based and practical examples
An Excursion into the Statistical Properties of Hedge Funds
This paper provides an overview of the most important statistical properties of individual hedge fund returns. We find that the net-of-fees monthly returns of the average individual hedge fund exhibit significant degrees of negative skewness, excess kurtosis, as well as positive first-order serial correlation. The correlations between hedge funds in the same strategy group are of the same order of magnitude as the correlations between funds in different strategy groups and relatively low. Only 10-20% of the variation in the average individual hedge fund’s returns can be explained by what happens in the US equity and bond markets. Compared to individual funds, portfolios of hedge funds tend to exhibit lower skewness, higher serial correlation and higher correlation with stocks and bonds. Movements in the US equity and bond markets still only explain 20-40% of the variation in hedge fund portfolios returns though. Finally, an equally-weighted portfolio of all funds in our sample offers a 2.76% higher mean return than the average fund of funds. This strongly suggests that the timing and fund picking activities of the average fund of funds are not rewarded by a higher return.
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Detection of Aliphatically Bridged Multi-Core Polycyclic Aromatic Hydrocarbons in Sooting Flames with Atmospheric-Sampling High-Resolution Tandem Mass Spectrometry.
This paper provides experimental evidence for the chemical structures of aliphatically substituted and bridged polycyclic aromatic hydrocarbon (PAH) species in gas-physe combustion environments. The identification of these single- and multicore aromatic species, which have been hypothesized to be important in PAH growth and soot nucleation, was made possible through a combination of sampling gaseous constituents from an atmospheric pressure inverse coflow diffusion flame of ethylene and high-resolution tandem mass spectrometry (MS-MS). In these experiments, the flame-sampled components were ionized using a continuous VUV lamp at 10.0 eV and the ions were subsequently fragmented through collisions with Ar atoms in a collision-induced dissociation (CID) process. The resulting fragment ions, which were separated using a reflectron time-of-flight mass spectrometer, were used to extract structural information about the sampled aromatic compounds. The high-resolution mass spectra revealed the presence of alkylated single-core aromatic compounds and the fragment ions that were observed correspond to the loss of saturated and unsaturated units containing up to a total of 6 carbon atoms. Furthermore, the aromatic structures that form the foundational building blocks of the larger PAHs were identified to be smaller single-ring and pericondensed aromatic species with repetitive structural features. For demonstrative purposes, details are provided for the CID of molecular ions at masses 202 and 434. Insights into the role of the aliphatically substituted and bridged aromatics in the reaction network of PAH growth chemistry were obtained from spatially resolved measurements of the flame. The experimental results are consistent with a growth mechanism in which alkylated aromatics are oxidized to form pericondensed ring structures or react and recombine with other aromatics to form larger, potentially three-dimensional, aliphatically bridged multicore aromatic hydrocarbons
Superfluid and insulating phases of fermion mixtures in optical lattices
The ground state phase diagram of fermion mixtures in optical lattices is
analyzed as a function of interaction strength, fermion filling factor and
tunneling parameters. In addition to standard superfluid, phase-separated or
coexisting superfluid/excess-fermion phases found in homogeneous or
harmonically trapped systems, fermions in optical lattices have several
insulating phases, including a molecular Bose-Mott insulator (BMI), a
Fermi-Pauli (band) insulator (FPI), a phase-separated BMI/FPI mixture or a
Bose-Fermi checkerboard (BFC). The molecular BMI phase is the fermion mixture
counterpart of the atomic BMI found in atomic Bose systems, the BFC or BMI/FPI
phases exist in Bose-Fermi mixtures, and lastly the FPI phase is particular to
the Fermi nature of the constituent atoms of the mixture.Comment: 4 pages with 3 figures (Published version
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