On Optimal Detection of Point Sources in CMB Maps

Point-source contamination in high-precision Cosmic Microwave Background (CMB) maps severely affects the precision of cosmological parameter estimates. Among the methods that have been proposed for source detection, wavelet techniques based on ``optimal'' filters have been proposed.In this paper we show that these filters are in fact only restrictive cases of a more general class of matched filters that optimize signal-to-noise ratio and that have, in general, better source detection capabilities, especially for lower amplitude sources. These conclusions are confirmed by some numerical experiments. \keywords{Methods: data analysis -- Methods: statisticalComment: 6 pages, 3 figure

Super stellar clusters with a bimodal hydrodynamic solution: an Approximate Analytic Approach

We look for a simple analytic model to distinguish between stellar clusters undergoing a bimodal hydrodynamic solution from those able to drive only a stationary wind. Clusters in the bimodal regime undergo strong radiative cooling within their densest inner regions, which results in the accumulation of the matter injected by supernovae and stellar winds and eventually in the formation of further stellar generations, while their outer regions sustain a stationary wind. The analytic formulae are derived from the basic hydrodynamic equations. Our main assumption, that the density at the star cluster surface scales almost linearly with that at the stagnation radius, is based on results from semi-analytic and full numerical calculations. The analytic formulation allows for the determination of the threshold mechanical luminosity that separates clusters evolving in either of the two solutions. It is possible to fix the stagnation radius by simple analytic expressions and thus to determine the fractions of the deposited matter that clusters evolving in the bimodal regime blow out as a wind or recycle into further stellar generations.Comment: 5 pages, 4 figures, accepted by A&

Chandra view of Kes 79: a nearly isothermal SNR with rich spatial structure

A 30 ks \chandra ACIS-I observation of Kes 79 reveals rich spatial structures, including many filaments, three partial shells, a loop and a ``protrusion''. Most of them have corresponding radio features. Regardless of the different results from two non-equilibrium ionization (NEI) codes, temperatures of different parts of the remnant are all around 0.7 keV, which is surprisingly constant for a remnant with such rich structure. If thermal conduction is responsible for smoothing the temperature gradient, a lower limit on the thermal conductivity of $\sim$ 1/10 of the Spitzer value can be derived. Thus, thermal conduction may play an important role in the evolution of at least some SNRs. No spectral signature of the ejecta is found, which suggests the ejecta material has been well mixed with the ambient medium. From the morphology and the spectral properties, we suggest the bright inner shell is a wind-driven shell (WDS) overtaken by the blast wave (the outer shell) and estimate the age of the remnant to be $\sim$ 6 kyr for the assumed dynamics. Projection is also required to explain the complicated morphology of Kes 79.Comment: 12 pages, 6 figures (3 in color), ApJ, in press, April 20, 200

Gansu Studio: 'Plug-in' school unit for rural China

Gansú ‘Plug-in’ Studio was a community outreach project based in China developed over a course of 2 years (2014-2016). It proposed a complementary approach of education to improve quality of learning in primary schools in rural areas. The premise for the work was to engage higher education institutions such as UNNC and primary education institutions, such as HEPAN, by exchange of resources, (e.g. physical or human - staff and students as well as contexts as real opportunities for learning). It worked using design as a tool for development and environmental awareness. It worked in partnership with industry and government institutions and it involved over 120 students and 15 staff from 5 different areas (Architecture, Product Design, Environmental Engineering, Film Studies and English/Education). Through interactive workshops with academics and industry practitioners, UNNC students were guided to realise their ideas through innovative design and sustainable engineering solutions, also developed their communication and team working skills for real to help rural education and community development. Meanwhile, pupils and teachers in rural areas could develop sufficiently as their urban counterparts through this connected learning hub. The purpose of this paper is to discuss the processes and outcomes of Gansu Studio. The Plug-in Gansu Unit was designed to be the first net positive energy rural school building in China producing an estimated 18304 kWh/year of renewable energy to the school and reverting back to the county grid an annual extra clean energy 2304kWh/annum upon completion. An estimated 22 tons of water per year would be also saved

Star clusters and the structure of the ISM. Tunnels and wakes in giant extragalactic HII regions

Several structures have been discovered embedded in regions of recent or ongoing star formation, which point to the importance of the interaction between fast moving wind-blowing stars and their environment. Using hydrodynamic simulations, we investigate the passage through the interstellar medium of a supersonic stellar wind source, and show how it can naturally lead to the formation of tubes, channels and swamps of globules as interfaces are crossed. The results are in excellent agreement with observation of 30 Doradus.Comment: 12 pages + 5 figures (GIF format) - Accepted for pub. in Astrophys. J. Letter

Drivers of Business-to-Business (B2B) Sales Success and the role of Digitalization after COVID-19 Disruptions

Purpose - The purpose of this research is to investigate the drivers of business-to-business sales success and the role of digitalization, in a selling and sales management landscape being disrupted by COVID-19. Design/methodology/approach – The methodology follows a discovery-oriented grounded theory approach which consists of a two-stage qualitative study with sales professionals in Chile, and a Fuzzy-Set Qualitative Comparative Analysis (fsQCA). Findings - This research shows that interfunctional coordination, agility in the selling process, and business customer engagement are critical determinants of B2B sales success, while digitalization moderates these relationships. Originality/value - This research responds to a call for more research on the impact of digitalization on business relationships in different contexts and perspectives. We study the Chilean context, through a two-stage qualitative study, and a fsQCA analysis, which constitutes a novel combination in this stream of research