The SDSS-GALEX viewpoint of the truncated red sequence in field environments at z~0

We combine GALEX near-UV photometry with a volume-limited sample of local (0.005<z<0.037) SDSS DR4 galaxies to examine the composition and the environmental dependencies of the optical and UV-optical colour-magnitude (C-M) diagrams. We find that ~30% of red sequence galaxies in the optical C-M diagram show signs of ongoing star-formation from their spectra having EW(Halpha)>2A. This contamination is greatest at faint magnitudes (Mr>-19) and in field regions where as many as three-quarters of red sequence galaxies are star-forming, and as such has important consequences for following the build-up of the red sequence. We find that the NUV-r colour instead allows a much more robust separation of passively-evolving and star-forming galaxies, which allows the build-up of the UV-selected red sequence with redshift and environment to be directly interpreted in terms of the assembly of stellar mass in passively-evolving galaxies. We find that in isolated field regions the number density of UV-optical red sequence galaxies declines rapidly at magnitudes fainter than Mr~-19 and appears completely truncated at Mr~-18. This confirms the findings of Haines et al. (2007) that no passively-evolving dwarf galaxies are found more than two virial radii from a massive halo, whether that be a group, cluster or massive galaxy. These results support the downsizing paradigm whereby the red sequence is assembled from the top down, being already largely in place at the bright end by z~1, and the faint end filled in at later epochs in clusters and groups through environment-related processes such as ram-pressure stripping or galaxy harassment.Comment: 12 pages, 7 figures, MNRAS submitte

Liability for Leaving a Firearm Accessible to Children

Enmeshed in the right to possess a firearm is the duty of care. Thus, the duty of care applies not only to using a firearm, but also to safeguarding the firearm from reasonably anticipated improper use by others. The liability of a person for permitting, or for leaving, a firearm accessible to children has been based upon failure to exercise the required duty of care in regard to a dangerous instrumentality.It is the objective of this note to consider whether or not the doctrine of absolute liability should be extended to hold that when a person permits a child to have a firearm, or leaves one accessible to him, he is absolutely liable for any injury or damage to real or personal property that occurs after the firearm has been discharged by the child

Electronic transport within a quasi two-dimensional model for rubrene single-crystal field effect transistors

Spectral and transport properties of the quasi two-dimensional adiabatic Su-Schrieffer-Heeger model are studied adjusting the parameters in order to model rubrene single-crystal field effect transistors with small but finite density of injected charge carriers. We show that, with increasing temperature $T$, the chemical potential moves into the tail of the density of states corresponding to localized states, but this is not enough to drive the system into an insulating state. The mobility along different crystallographic directions is calculated including vertex corrections which give rise to a transport lifetime one order of magnitude smaller than spectral lifetime of the states involved in the transport mechanism. With increasing temperature, the transport properties reach the Ioffe-Regel limit which is ascribed to less and less appreciable contribution of itinerant states to the conduction process. The model provides features of the mobility in close agreement with experiments: right order of magnitude, scaling as a power law $T^{-\gamma}$, with $\gamma$ close or larger than two, and correct anisotropy ratio between different in-plane directions. Due to a realistic high dimensional model, the results are not biased by uncontrolled approximations.Comment: 10 pages, 9 figures, Submitte

The mechanical design of a gas supply and mixing system for the AMS-02 particle detector onboard the international space station

Abstract The Alpha Magnetic Spectrometer 02 is a particle physics experiment that will search for antimatter, dark matter, and measure cosmic rays in space aboard the International space station for 3 years . It is comprised of an array of sub-detectors: Transition Radiation Detector (TRD); Time of Flight detector; Anti-Coincidence Counter; Silicon Tracker; Ring Imaging Cherenkov counter; Electromagnetic Calorimeter and requires the operation of a cryogenic super conducting magnet at its core. It is built by an international collaboration of more than 100 scientists spread all over Europe, USA and the far East. The TRD that is located above the Cryomagnet and Upper Time of Flight, consists of several layers of straw modules interleaved with a fiber fleece material and arranged in a conical octagon structure built out of a carbon fiber/aluminum honeycomb sandwich. A charged particle traversing this detector produces characteristic electromagnetic radiation in each layer that is measured in the gas filled array of straw tubes. From this, the mass and momentum of the particle can be measured provided the tubes are filled with the proper gas mixture. The TRD gas supply stores 50 kg of gas corresponding to 8100 l Xe and 2000 l CO2 at 1 atm , filters, mixes, recirculates, and purges a daily supply of Xe/CO2 (80%/20%) gaseous mixture, thus supplying the TRD with clean, mixed gas for the 3-year ISS mission. Designing and building this reliable, weight optimised system to withstand launch loads and the harsh space environment presented a formidable engineering challenge. Adding to the complexity of the system was that a flexible valve/pump arrangement was needed to control mixture ratio, circulation flow and pressure, and purging. These studies are presented in the paper

Characterization of Building Thermal Energy Consumption at the Urban Scale

The ongoing urban transition toward decarbonized energy systems has raised the attention on local energy planning practices. Besides the multiple actors involved in the planning process, the complexity of the urban energy systems requires the elaboration of heterogeneous data. In such contest, the paper introduces and compares two GIS-based ethodologies for supporting the spatial characterization of the local residential built environment in terms of building distribution and space heating energy consumption. Starting from the assessment of residential consumption, a third method for the characterization of non-residential building thermal energy consumption is proposed. From a bottom-up perspective, in both residential models all the buildings are geo-referenced and clustered according to their thermo-physical characteristics. From a top-down perspective, energy balance data are used to calibrate the bottom-up results and to match the total building loads. The procedure, tested on the city of Turin as case study, allows assessing the energy use of buildings and to create urban energy maps. The energy spatial characterization of a territory is the basis for performing short and long-term scenarios analysis. Results of this method can be useful to: i. decision maker to understand the current state of the territorial energy consumption to identify critical energy intense areas; ii. citizens for visualising their energy consumption and iii. researchers for setting up the basis of further urban analysis

A multilevel method to optimize the sustainable construction works

The new European standard family of CEN TC 350, still in progress, is supposed to be as guidelines of the performance oriented building assessment. The perspective suggested by the standard family is multidisciplinary. The future developments are expected to go more and more into the direction of the integration of the three major components in the life cycle: environmental, social, economic. This is a sufficient ground to start managing any case of construction works as an interdisciplinary project, thinking and planning any action as the integration of a certain number of actions, with a multiscale and multilevel approach. The paper reports on the research focused on the development of inductive, logical / operational guidelines, aimed at optimizing the sustainable management of construction works. The identification of a multiscale and multilevel strategy aiming at supporting the decision-making process, applied to the “Leonardo da Vinci Sustainable Campus” project in Milan, with respect to the energy, environmental, social and economic performances, is focused on key objectives / criteria / indicators. The holistic approach and the involvement of the stakeholders in the method, supported by multiple criteria decision making (MCDM) models and methods, aims at giving transparent and shared answer to the search of the best technical solutions and strategies in a large sustainable perspective

Development of interconnected silicon micro-evaporators for the on-detector electronics cooling of the future ITS detector in the ALICE experiment at LHC

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The design of the future High Energy Physics (HEP) particle detectors for the upgrade of the LHC (Large Hadron Collider) experiments at CERN (European Organization for Nuclear Research) is pushing technological frontiers to the limit trying to reach unprecedented accuracy in particles identification and particle production dynamics in ultra-relativistic hadron collisions. The thermal management of the on-detector electronics and the development of low mass integrated cooling systems have become a crucial task in the design of silicon tracking detectors for HEP applications. In this paper, we present a novel concept of low mass interconnected silicon microchannel devices for the future Inner Tracking System of the ALICE (A Large Ion Collider Experiment) detector at LHC. This innovative design achieves the requirements of the detector while minimizing the total material budget

Chemo-Archaeological Downsizing in a Hierarchical Universe: Impact of a Top Heavy IGIMF

We make use of a semi-analytical model of galaxy formation to investigate the origin of the observed correlation between [a/Fe] abundance ratios and stellar mass in elliptical galaxies. We implement a new galaxy-wide stellar initial mass function (Top Heavy Integrated Galaxy Initial Mass Function, TH-IGIMF) in the semi-analytic model SAG and evaluate its impact on the chemical evolution of galaxies. The SFR-dependence of the slope of the TH-IGIMF is found to be key to reproducing the correct [a/Fe]-stellar mass relation. Massive galaxies reach higher [a/Fe] abundance ratios because they are characterized by more top-heavy IMFs as a result of their higher SFR. As a consequence of our analysis, the value of the minimum embedded star cluster mass and of the slope of the embedded cluster mass function, which are free parameters involved in the TH-IGIMF theory, are found to be as low as 5 solar masses and 2, respectively. A mild downsizing trend is present for galaxies generated assuming either a universal IMF or a variable TH-IGIMF. We find that, regardless of galaxy mass, older galaxies (with formation redshifts > 2) are formed in shorter time-scales (< 2 Gyr), thus achieving larger [a/Fe] values. Hence, the time-scale of galaxy formation alone cannot explain the slope of the [a/Fe]-galaxy mass relation, but is responsible for the big dispersion of [a/Fe] abundance ratios at fixed stellar mass.We further test the hyphothesis of a TH-IGIMF in elliptical galaxies by looking into mass-to-light ratios, and luminosity functions. Models with a TH-IGIMF are also favoured by these constraints. In particular, mass-to-light ratios agree with observed values for massive galaxies while being overpredicted for less massive ones; this overprediction is present regardless of the IMF considered.Comment: 24 pages, 15 figures, 2 tables. (Comments most welcome). Summited to MNRA

Dynamic ride sharing service: are users ready to adopt it?

Nowadays we are experiencing a shift of paradigm from ownership of goods to sharing goods and experiences. The “sharing economy” paradigm will change the way people experience everyday life in many sectors. In this paper we are focusing on the urban transportation experience presenting a user centric design of an experimental dynamic ridesharing service for Italian users, called VirtualBus [1]. The proposed service is based on a mobile application that allows people to get arrangement in real time for sharing car rides in an urban area, both as “driver” or “passenger”. A smart matching algorithm will provide, within a short time, the best matching between the driver and the passenger learning from users’ feedbacks and improving its suggestions overtime to better fulfill users’ expectations. The service was designed, prototyped and tested involving users in every step, starting from a vision board with the target Personas. Then, a first raw prototype of the mobile application was designed and tested during specific focus group sessions. During the focus groups users highlighted both the importance of defining rewarding and payment rules and some concerns about privacy and reliability of drivers and passengers. Moreover, a large scale questionnaire, with more than 500 respondents, was distributed with the focus on two big Italian cities, Turin and Rome. The questionnaire analysis gave many interesting insights about the city commuting habits and its results were used to enrich the previously designed Personas with the aim of enhancing real users’ scenarios. Next steps will involve real users on selected cities as a test-bed of both the technical solution and the users’ acceptability of a new way of experiencing the urban commuting