SnapShot: Tumor evolution

Understanding how tumors grow and evolve over time is crucial to help shed light on the underlying reasons why treatments fail and tumors metastasize. This SnapShot provides a brief introduction into the main concepts of tumor evolution

Two energy suppliers are better than one: survey experiments on consumer engagement with local energy in GB

Usually consumers have a single energy supplier. Permitting consumers to take on additional contracts with local suppliers in a multiple-supplier model could support growth of local renewable energy. The aims of this study were to assess the attractiveness of a multiple-supplier model and to understand whether consumers would be more likely to engage with local energy suppliers in a multiple-supplier model or the current single supplier model. An additional aim was to explore the role of default effects and cognitive biases associated with remaining with incumbent suppliers (loss-aversion, cognitive effort and implied endorsement). Two nationally representative survey experiments were conducted in Great Britain (n = 1042, n = 762). Results showed that participants were significantly more likely to engage with local energy suppliers under a multiple-supplier model than the current single supplier model. In one experiment, consumers’ preference for adding a local supplier under a multiple-supplier model was so strong that it overcame default effects. The perception that the supplier has been recommended (i.e. implied endorsement) was the most robust mechanism associated with remaining with default suppliers, suggesting that explicit endorsement of local energy suppliers may encourage uptake. Results suggest multiple-supplier models are likely to be a promising avenue for increased energy market engagement

EXPERIMENTAL VALIDATION OF A DYNAMIC MODEL FOR A RESIDENTIAL HEAT PUMP WITH IMMERSED CONDENSER

This work describes the validation of a dynamic model for a vapor compression residential heat pump with an immersed condenser. A detailed description of the modelling methodology for each component (compressor, capillary tube, evaporator, and immersed condenser) and the solution methodology employed in the complete heat pump system are presented. The main contribution of this work is in the dynamic modeling of the thermal processes occurring within the heat exchangers. Instabilities of the solutions for the heat exchangers are minimized by considering spatially and temporal varying errors. Another contribution of the model is the investigation of the temperature distribution inside the water storage tank, which highlights the possibility of using immersed condensers for this purpose without significant thermal stratification in the tank. Simulation results and experimental results are compared for transient operations using multivariate profiles of temperature, pressure and mass flow rates in heat exchangers during the water heating process

Doubly resonant optical nanoantenna arrays for polarization resolved measurements of surface-enhanced Raman scattering

We report that rhomb-shaped metal nanoantenna arrays support multiple plasmonic resonances, making them favorable bio-sensing substrates. Besides the two localized plasmonic dipole modes associated with the two principle axes of the rhombi, the sample supports an additional grating-induced surface plasmon polariton resonance. The plasmonic properties of all modes are carefully studied by far-field measurements together with numerical and analytical calculations. The sample is then applied to surface-enhanced Raman scattering measurements. It is shown to be highly efficient since two plasmonic resonances of the structure were simultaneously tuned to coincide with the excitation and the emission wave- length in the SERS experiment. The analysis is completed by measuring the impact of the polarization angle on the SERS signal.Comment: 13 pages, 5 figure

Water in the Near IR spectrum of Comet 8P/Tuttle

High resolution spectra of Comet 8P/Tuttle were obtained in the frequency range 3440.6-3462.6 cm-1 on 3 January 2008 UT using CGS4 with echelle grating on UKIRT. In addition to recording strong solar pumped fluorescent (SPF) lines of H2O, the long integration time (152 miutes on target) enabled eight weaker H2O features to be assigned, most of which had not previously been identified in cometary spectra. These transitions, which are from higher energy upper states, are similar in character to the so-called 'SH' lines recorded in the post Deep Impact spectrum of comet Tempel 1 (Barber et al., 2007). We have identified certain characteristics that these lines have in common, and which in addition to helping to define this new class of cometary line, give some clues to the physical processes involved in their production. Finally, we derive an H2O rotational temperature of 62+/- K and a water production rate of (1.4+/-0.3)E28 molecules/s.Comment: Paper has been accepted for publication by MNRAS (11/06/09

Haplotype block structure is conserved across mammals

Genetic variation in genomes is organized in haplotype blocks, and species-specific block structure is defined by differential contribution of population history effects in combination with mutation and recombination events. Haplotype maps characterize the common patterns of linkage disequilibrium in populations and have important applications in the design and interpretation of genetic experiments. Although evolutionary processes are known to drive the selection of individual polymorphisms, their effect on haplotype block structure dynamics has not been shown. Here, we present a high-resolution haplotype map for a 5-megabase genomic region in the rat and compare it with the orthologous human and mouse segments. Although the size and fine structure of haplotype blocks are species dependent, there is a significant interspecies overlap in structure and a tendency for blocks to encompass complete genes. Extending these findings to the complete human genome using haplotype map phase I data reveals that linkage disequilibrium values are significantly higher for equally spaced positions in genic regions, including promoters, as compared to intergenic regions, indicating that a selective mechanism exists to maintain combinations of alleles within potentially interacting coding and regulatory regions. Although this characteristic may complicate the identification of causal polymorphisms underlying phenotypic traits, conservation of haplotype structure may be employed for the identification and characterization of functionally important genomic regions