2,970 research outputs found
The impact of polarized extragalactic radio sources on the detection of CMB anisotropies in polarization
Recent polarimetric surveys of extragalactic radio sources (ERS) at
frequencies \nu>1GHz are reviewed. By exploiting all the most relevant data on
the polarized emission of ERS we study the frequency dependence of polarization
properties of ERS between 1.4 and 86GHz. For flat-spectrum sources the median
(mean) fractional polarization increases from 1.5% (2-2.5%) at 1.4GHz to 2.5-3%
(3-3.5%) at \nu>10GHz. Steep-spectrum sources are typically more polarized,
especially at high frequencies where Faraday depolarization is less relevant.
As a general result, we do not find that the fractional polarization of ERS
depends on the total flux density at high radio frequencies, i.e >20GHz.
Moreover, in this frequency range, current data suggest a moderate increase of
the fractional polarization of ERS with frequency. A formalism to estimate ERS
number counts in polarization and the contribution of unresolved polarized ERS
to angular power spectra at Cosmic Microwave Background (CMB) frequencies is
also developed and discussed. As a first application, we present original
predictions for the Planck satellite mission. Our current results show that
only a dozen polarized ERS will be detected by the Planck Low Frequency
Instrument (LFI), and a few tens by the High Frequency Instrument (HFI). As for
CMB power spectra, ERS should not be a strong contaminant to the CMB E-mode
polarization at frequencies \nu>70GHz. On the contrary, they can become a
relevant constraint for the detection of the cosmological B--mode polarization
if the tensor-to-scalar ratio is <0.01.Comment: 14 pages, 7 figures. Accepted for publication in Advances in
Astronomy, Special Issue: "Astrophysical Foregrounds in Microwave Surveys",
editor-in-chief C. Burigana, (www.hindawi.com
Effects of Theory of Mind Training on the False Belief Understanding of Deaf and Hard of Hearing Students in Prekindergarten and Kindergarten
Data from a growing number of research studies indicate that children with hearing loss are delayed in Theory of Mind (ToM) development when compared to their typically developing, hearing peers. While other researchers have studied the developmental trajectories of ToM in school-age students who are deaf and hard of hearing (DHH), a limited number have addressed the need for interventions for this population. The present study extends the current research on ToM interventions to the PreKindergarten and Kindergarten levels. This study used a single-case multiple-baseline multiple-probe across skills design with replications across classrooms to examine the effects of a ToM intervention on participants’ false belief understanding as well as outcomes on a near generalization measure (i.e., Sally-Anne Task, Baron-Cohen, Firth, Leslie, 1985) and a far generalization measure (i.e., five-task ToM developmental scale, Wellman & Liu, 2004). A thought bubble intervention (i.e., a visual representation of what people are thinking) developed by Wellman and Peterson (2013) was modified in key areas: (a) participants were substantially younger than the population in the original study and thus required a pre-teaching phase addressing vocabulary and materials, (b) manipulable materials were created from the description provided in the Wellman and Peterson (2013) study along with parallel materials used in assessment probes, (c) a certified teacher of DHH children provided direct instruction to participants in a small group setting, (d) study length was increased to 25 weeks, and (e) methodological design change (i.e., group design to single-case design). These modifications addressed the need for evidence-based ToM interventions that are both proactive and easily implemented by teachers in a classroom setting. Results from the single-case design portion of the study indicate a functional relation between the thought bubble intervention and the participants’ acquisition of the targeted skills in each stage, although progress was not uniform. Results from the pre-post assessments indicate that the children did make progress up the scale, however, children who used spoken language tended to proceed faster through the stages than those who used sign language. These results inform the field in regard to the efficacy and feasibility of a ToM intervention for young DHH children
Emergence and persistence of communities in coevolutionary networks
We investigate the emergence and persistence of communities through a
recently proposed mechanism of adaptive rewiring in coevolutionary networks. We
characterize the topological structures arising in a coevolutionary network
subject to an adaptive rewiring process and a node dynamics given by a simple
voterlike rule. We find that, for some values of the parameters describing the
adaptive rewiring process, a community structure emerges on a connected
network. We show that the emergence of communities is associated to a decrease
in the number of active links in the system, i.e. links that connect two nodes
in different states. The lifetime of the community structure state scales
exponentially with the size of the system. Additionally, we find that a small
noise in the node dynamics can sustain a diversity of states and a community
structure in time in a finite size system. Thus, large system size and/or local
noise can explain the persistence of communities and diversity in many real
systems.Comment: 6 pages, 5 figures, Accepted in EPL (2014
Market Feedback and Team Commitment in Radical Product Innovation Process
Previous research has considered how exploratory market learning processes moderate market and technological uncertainty in radical product development. Scholars argue that new product development (NPD) teams may increase the chances of success of radically new projects by acquiring, assimilating and implementing new information from market feedback. However, research has not tackled how information is assimilated by the NPD team and to what extent the process of information implementation occurs. In this article, we begin to fill the need for such research by investigating the interaction between internal team values (beliefs and possibly ideology) and external market feedback / information in radical projects. Via the lens of a 2-year longitudinal participant-observation study, we suggest that information assimilation is not automatic, but rather influenced in interesting ways by internal team values. The findings imply that shared team values act as a selective assimilation mechanism determining whether a development team will act on user feedback. Furthermore, the type of information (e.g., functional vs. conceptual feedback) processed by the development team acts as a moderating factor on the relationship between the team values and information processing
THE AMBON OF SANT'ANDREA IN PISTOIA: A COMPARISON BETWEEN LASER SCANNER AND PHOTOGRAMMETRIC DIGITIZATION OF MARBLE SURFACES
An alternative strategy for cloning minor permeases in Aspergillus nidulans
The uapC gene was cloned by complementation of the cryosensitive phenotype of uapA mutants following the instant gene bank method. The analysis of the transformants is presented and a strategy to clone other transport related genes is proposed
The influence of industry downturns on the propensity of product versus process innovation
This article sheds light on how industry fluctuations affect firms' propensity to innovate. We test two seemingly conflicting arguments that suggest how firms are more or less inclined to engage in innovation activities during industry fluctuations. By studying a panel of 622 Italian manufacturing firms during the period 1995-2003, we show how differentiating between product and process innovation may help reconcile the theory of opportunity cost of innovation with the cash-flow effect argument. We find that industry downturns are related to product and process innovation in different ways: firms tend to invest in product innovation rather than process innovation in downturns. The findings have implications for both theory (showing when the opportunity cost of innovation dominates) and research design (showing the importance of both the input and output measures in innovation studies and how they might influence the results
Optimization of graphene-based materials outperforming host epoxy matrices
The degree of graphite exfoliation and edge-carboxylated layers can be controlled and balanced to design lightweight materials characterized by both low electrical percolation thresholds (EPT) and improved mechanical properties. So far, this challenging task has been undoubtedly very hard to achieve. The results presented in this paper highlight the effect of exfoliation degree and the role of edge-carboxylated graphite layers to give self-assembled structures embedded in the polymeric matrix. Graphene layers inside the matrix may serve as building blocks of complex systems that could outperform the host matrix. Improvements in electrical percolation and mechanical performance have been obtained by a synergic effect due to finely balancing the degree of exfoliation and the chemistry of graphene edges which favors the interfacial interaction between polymer and carbon layers. In particular, for epoxy-based resins including two partially exfoliated graphite samples, differing essentially in the content of carboxylated groups, the percolation threshold reduces from 3 wt% down to 0.3 wt%, as the carboxylated group content increases up to 10 wt%. Edge-carboxylated nanosheets also increase the nanofiller/epoxy matrix interaction, determining a relevant reinforcement in the elastic modulus
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