1,799 research outputs found
Teams in New Ventures: Gender, Human Capital and Motivation
Purpose- This paper dismantles the idea that sex per se explains entrepreneurial outcomes and demonstrates the influence of a gendered motivation on forging and shaping new venture teams, which is a disruptive choice affecting the future of start-ups.
Methods- A two-level research model is validated on data from the PSED II, with a system of simultaneous equations. Firstly, we test if team features affect the performance of new ventures; then, we investigate determinants of team features with a focus on sex and motivation of nascent entrepreneurs.
Findings- Human capital (HC) in terms of education and experience of team members consistently explains
venture evolution only when considering the larger team of affiliates. The HC gathered by nascent
entrepreneurs is not due to the simplistic sex condition, but rather to a gendered motivation related to the
inferior need of achievement of women.
Research limitations- Limitations of discretionary scoring assigned to items of the PSED II survey are
present, but unavoidable when processing qualitative data.
Social and Practical implications- Women need to be (culturally) educated on how to re-balance their
personal motivation towards entrepreneurship by fostering their incentives for achievement. Political and
educational programs could trigger success in the creation of new businesses led by women.
Originality/value- This paper contributes to the literature on nascent entrepreneurship, focusing on the
entrepreneurial teams in the initial phase of business creation, and provides the basis for further studies
aimed at eradicating the stereotypes of gender roles that lead women to self-exclusion and organizational
errors
A time-varying SIRD model for dynamic vaccination strategies against COVID-19
The COVID-19 pandemic has demonstrated how the optimal allocation of the limited doses of vaccine available represents one of the main useful measures to mitigate the transmission of the infection and reduce the mortality associated with it, especially at an early stage of the pandemic. The use of a compartmental model allows us to understand which population groups to vaccinate and to what extent to act depending on the type of health or social objective to be achieved
The effects of superconductor-stabilizer interfacial resistance on quench of current-carrying coated conductor
We present the results of numerical analysis of a model of normal zone
propagation in coated conductors. The main emphasis is on the effects of
increased contact resistance between the superconducting film and the
stabilizer on the speed of normal zone propagation, the maximum temperature
rise inside the normal zone, and the stability margins. We show that with
increasing contact resistance the speed of normal zone propagation increases,
the maximum temperature inside the normal zone decreases, and stability margins
shrink. This may have an overall beneficial effect on quench protection quality
of coated conductors. We also briefly discuss the propagation of solitons and
development of the temperature modulation along the wire.Comment: To be published in Superconductor Science and Technology. This
preprint contains one animated figure (Fig. 6(a)). when asked whether you
want to play the content, click "Play". Acrobat Reader (Windows and Mac, but
not Linux) will play embedded flash movies. In the printed copy Fig. 6(b)
will show the temperature profile at gamma t=15
Signature of stripe pinning in optical conductivity
The response of charge stripes to an external electric field applied
perpendicular to the stripe direction is studied within a diagrammatic approach
for both weak and strong pinning by random impurities. The sound-like mode of
the stripes described as elastic strings moves to finite frequency due to
impurity pinning. By calculating the optical conductivity we determine this
characteristic energy scale for both a single stripe and an array of
interacting stripes. The results explain the anomalous far-infrared peak
observed recently in optical-conductivity measurements on cuprates.Comment: Revised version, to appear in Phys. Rev.
The oxygen-assisted transformation of propane to COx/H2 through combined oxidation and WGS reactions catalyzed by vanadium oxide-based catalysts
This paper reports about the gas-phase oxidation of propane catalyzed by bulk vanadium oxide and by alumina- and silica-supported vanadium oxide. The reaction was studied with the aim of finding conditions at which the formation of H2 and CO2 is preferred over that of CO, H2O and of products of alkane partial oxidation. It was found that with bulk V2O5 considerable amounts of H2 are produced above 400 8C, the temperature at which the limiting reactant, oxygen, is totally consumed. The formation of H2 derived from the combination of: (i) oxidation reactions, with generation of CO, CO2, oxygenates (mainly acetic acid), propylene and H2O, all occurring in the fraction of catalytic bed that operated in the presence of gas-phase oxygen, and (ii) WGS reaction, propane dehydrogenation and coke formation, that instead occurred in the fraction of bed operating under anaerobic conditions. This combination of different reactions in a single catalytic bed was possible because of the reduction of V2O5 to V2O3 at high temperature, in the absence of gas-phase oxygen. In fact, vanadium sesquioxide was found to be an effective catalyst for the WGS, while V2O5 was inactive in this reaction. The same combination of reactions was not possible when vanadium oxide was supported over high-surface area silica or alumina; this was attributed to the fact that in these catalysts vanadium was not reduced below the oxidation state V4+, even under reaction conditions leading to total oxygen conversion. In consequence, these catalysts produced less H2 than bulk vanadium oxide
Remote sensing techniques applied to geomorphological mapping of rocky coast: the case study of Gallinara Island (Western Liguria, Italy)
Geomorphological survey and mapping of the emerged and submerged coastal areas, particularly addressed to evaluate sea cliff instability within the assessment of coastal hazard and risk mitigation measures, require high resolution and georeferenced spatial data. Remote sensing techniques fully satisfy these needs and allow to obtain all information in a single short-lived survey campaign. An integrated survey by means of laser scanner and multibeam techniques coupled with aerial photos interpretation has been experienced along the rocky coast of the Gallinara Island (Western Liguria, Italy). The small extent of Gallinara, together with its particular meteo-marine climate conditions, makes the island a noteworthy case study. Multibeam and laser scanner technologies allowed to reconstruct the submerged and emerged rocky coast at high resolution. The accuracy of the 3D surface reconstructed by means of laser scanner used in profiler mode was tested and validated, by comparing with the static laser scanner survey method. The resulting data allowed to obtain significant geological and geomorphological information leading to the definition of rocky cliff stability conditions. \ua9 2019, \ua9 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group
Assessment of potential source regions of PM2.5 components at a southwestern Mediterranean site
A set of PM 2.5 samples ( n = 121) collected at an urban background location in Elche (in southeastern Spain) from December 2004 to November 2005 was analysed by particle-induced X-ray emission (PIXE) and ion chromatography in order to provide source identification and potential source locations. Positive matrix factorization (PMF) was used to estimate source profiles and their mass contributions. The PMF modelling identified six sources: aged sea salt (9.2%), ammonium sulphate (40.4%), soil dust related to Saharan outbreaks (13.0%), traffic 1 (18.9%), nitrate aerosol and traffic 2 (5.5%) and local soil dust (6.0%). Potential source contribution function (PSCF) was then used to identify potential source locations. Scarce influence from Mediterranean and European regions was found with the exception of the nitrate source, whose potential source areas were northern Italy and eastern France. Primary source regions for the remaining components (ammonium sulphate, soil dust-related to Saharan outbreaks and aged sea salt) with known mass contributions due to long-range transport have a marked Atlantic and North African location, primarily between Morocco and northwestern Algeria. DOI: 10.1111/j.1600-0889.2010.00510.
40. The gas-phase ammoxidation of n-hexane to unsaturated C6 dinitriles, intermediates for hexamethylenediamine synthesis
This paper reports about an investigation on the catalytic gas-phase ammoxidation of n-hexane aimed at the production of 1,6-C6 dinitriles, precursors for the synthesis of hexamethylenediamine. Catalysts tested were those also active and selective in the ammoxidation of propane to acrylonitrile: rutile-type V/Sb and Sn/V/Nb/Sb mixed oxides. Several N-containing compounds formed; however, the selectivity to cyano-containing aliphatic linear C6 compounds was low, due to the relevant contribution of side reactions such as combustion, cracking and formation of heavy compounds.INGLES
Superacid resin-based heterogeneous catalysts for the selective acylation of 1,2-methylenedioxybenzene
In this work, we firstly report on the use of highly active and selective Aquivion superacid resins as heterogeneous catalysts for the acylation of 1,2-methylenedioxybenzene (MDB) with propionic anhydride (AP). The reaction was investigated and optimized using solvent-free conditions to selectively produce 3,4-methylenedioxypropiophenone (MDP1P), a key intermediate for the manufacture of active ingredients used in insecticide formulations with a volume of production of roughly 3000 t/y. Interestingly, Aquivion-based catalysts allows to work in mild reaction conditions (i. e. 80 °C), obtaining MDP1P yields as high as 44 % after only 1 h of reaction (selectivity 83 %). A detailed study of the AP reactivity demonstrated its tendency to promote oligomerization reactions that, as confirmed by ex-situ and in-situ FT-ATR analyses, caused the deactivation of the catalyst forming surficial carbonaceous residues. In this context, a fast oxidation of the resin surface organic residues using a diluted HNO3 (or H2O2) solution was proven to be an efficient method to regenerate the catalyst, which can be reused for several reaction cycles. The results obtained in preliminary scale-up tests were basically unaffected by the reaction volume (up to 800 mL), paving the way for possible future applications of the process
Simple and effective deposition method for solar cell perovskite films using a sheet of paper
Most laboratories employ spin coating with application of antisolvent to achieve high efficiency in perovskite solar cells. However, this method wastes a lot of material and is not industrially usable. Conversely, large area coating techniques such as blade and slot-die require high precision engineering both for deposition of ink and for gas or for electromagnetic drying procedures that replace, out of necessity, anti-solvent engineering. Here we present a simple and effective method to deposit uniform high-quality perovskite films with a piece of paper as an applicator at low temperatures. We fabricated solar cells on flexible PET substrates manually with 11% power conversion efficiency. Deposition after soaking the sheet of paper in a green antisolvent improved the efficiency by 82% compared to when using dry paper as applicator. This new technique enables manual film deposition without any expensive equipment and has the potential to be fully automated for future optimization and exploitation
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