1,258 research outputs found
International scientific research on venture capital: a bibliometric and mapping analysis from the period 1978–2020
The aim of this study is to explore the relevance of scientific production on venture capital using bibliometric and mapping tools.We performed a search in Scopus, involving any document published between 1978 and 2020. We used bibliometric indicators to explore documents production, dispersion, distribution, time of duplication, and annual growth, as Price’s law of scientific literature growth, Lotka’s law, the transient index, and the Bradford model. We also calculated the participation index of the different countries and institutions. Finally, we explored the co-occurrence and thematic networks for the most frequently used terms in venture capital research through bibliometric mapping.A total of 1,230 original articles were collected from the timeframe 1978–2020. The model confirms that Price’s law is not fulfilled. Scientific production was better adjusted to linear growth (r = 0.9290) than exponential (r = 0.9161). Literature on venture capital research has increased its growth in the last 43 years at a rate of 7.9% per year, with a production that doubles its size every 9.1 years. The transience index was 79.91%, which indicates that most of the scientific production is due to a lot of authors with a small number of publications on the research topic. Bradford´s law shows that the scientific production in this area is widely distributed in multiple journals, and Lotka’s law indicates that the author’s distribution is heavily concentrated on small producers. The United States of America (USA) and the University of Pennsylvania present the highest production, contributing 31.22% and 1.63% of the total production of research on venture capital.The venture capital task has undergone a linear growth, with a very high rate of transience, which indicates the presence of numerous authors who sporadically publish on this topic. No evidence of a saturation point was observed in the scientific production analyzed, which makes it possible to conclude that the research in venture capital will continue to be in demand by the scientific community.The aim of this study is to explore the relevance of scientific production on venture capital using bibliometric and mapping tools.We performed a search in Scopus, involving any document published between 1978 and 2020. We used bibliometric indicators to explore documents production, dispersion, distribution, time of duplication, and annual growth, as Price’s law of scientific literature growth, Lotka’s law, the transient index, and the Bradford model. We also calculated the participation index of the different countries and institutions. Finally, we explored the co-occurrence and thematic networks for the most frequently used terms in venture capital research through bibliometric mapping.A total of 1,230 original articles were collected from the timeframe 1978–2020. The model confirms that Price’s law is not fulfilled. Scientific production was better adjusted to linear growth (r = 0.9290) than exponential (r = 0.9161). Literature on venture capital research has increased its growth in the last 43 years at a rate of 7.9% per year, with a production that doubles its size every 9.1 years. The transience index was 79.91%, which indicates that most of the scientific production is due to a lot of authors with a small number of publications on the research topic. Bradford´s law shows that the scientific production in this area is widely distributed in multiple journals, and Lotka’s law indicates that the author’s distribution is heavily concentrated on small producers. The United States of America (USA) and the University of Pennsylvania present the highest production, contributing 31.22% and 1.63% of the total production of research on venture capital.The venture capital task has undergone a linear growth, with a very high rate of transience, which indicates the presence of numerous authors who sporadically publish on this topic. No evidence of a saturation point was observed in the scientific production analyzed, which makes it possible to conclude that the research in venture capital will continue to be in demand by the scientific community
Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies
We study the spatial distribution of the physical properties and of oxygen
and nitrogen abundances in three Blue Compact Dwarf Galaxiess (HS 0128+2832, HS
0837+4717 and Mrk 930) with a reported excess of N/O in order to investigate
the nature of this excess and, particularly, if it is associated with
Wolf-Rayet (WR) stars We have observed these BCDs by using PMAS integral field
spectroscopy in the optical spectral range (3700 - 6900 {\AA}), mapping their
physical-chemical properties, using both the direct method and appropriate
strong-line methods. We make a statistical analysis of the resulting
distributions and we compare them with the integrated properties of the
galaxies. Our results indicate that outer parts of the three galaxies are
placed on the "AGN-zone" of the [NII]/H{\alpha} vs. [OIII]/H{\beta} diagnostic
diagram most likely due to a high N/O combined with the excitation structure in
these regions. From the statistical analysis, it is assumed that a certain
property can be considered as spatially homogeneous (or uniform) if a normal
gaussian function fits its distribution in several regions of the galaxy.
Moreover, a disagreement between the integrated properties and the mean values
of the distribution usually appears when a gaussian does not fit the
corresponding distribution. We find that for Mrk 930, the uniformity is found
for all parameters, except for electron density and reddening. The rotation
curve together with the H{\alpha} map and UV images, reveal a perturbed
morphology and possible interacting processes. The N/O is found to be constant
in the three studied objects at spatial scales of the order of several kpc so
we conclude that the number of WR stars estimated from spectroscopy is not
sufficient to pollute the ISM and to produce the observed N/O excess in these
objectsComment: 17 pages, 14 figures, accepted for publication in Astronomy &
Astrophysic
Assessment of Chemical Inhibitor Addition to Improve the Gas Production from Biowaste
The coexistence of sulphate-reducing bacteria and methanogenic archaea in the reactors during the anaerobic digestion from sulphate-containing waste could favor the accumulation of sulfide on the biogas, and therefore reduce its quality. In this study, the effect of sulphate-reducing bacteria inhibitor (MoO−2
4 ) addition in a two phase system from sulphate-containing municipal solid waste to improve the quality of the biogas has been investigated. The results showed that although SRB and sulphide production decreased, the use of inhibitor was not effective to improve the anaerobic digestion in a two phase
system from sulphate-containing waste, since a significant decrease on biogas and organic matter removal were observed. Before MoO−2 4 addition the average values of volatile solid were around 12 g/kg, after 5 days of inhibitor use, those values did exceed to 28 g/kg. Molybdate caused acidification in the reactor and it was according to decrease in the pH values. In relation to microbial consortia, the effect of inhibitor was a decrease in Bacteria (44%; 60% in sulphate-reducing bacteria) and Archaea (38%) population
Sistema de enfoque basado en dos espejos elípticos y un espejo plano rotatorio para un radar a 300 GHz
A focusing system for a 300 GHz radar with two target distances (5m and 10m) is proposed, having 1cm resolution in both cases. The focusing system is based on a gaussian telescope scheme and it has been designed using gaussian beam quasi-optical propagation theory with a homemade Matlab analysis tool. It has been translated into a real focusing system based on two elliptical mirrors and a plane mirror in order to have scanning capabilities and validated using the commercial antenna software GRAS
ALDH4A1 is an atherosclerosis auto-antigen targeted by protective antibodies
Cardiovascular disease (CVD) is the leading cause of mortality in the world, with most CVD-related deaths resulting from myocardial infarction or stroke. The main underlying cause of thrombosis and cardiovascular events is atherosclerosis, an inflammatory disease that can remain asymptomatic for long periods. There is an urgent need for therapeutic and diagnostic options in this area. Atherosclerotic plaques contain autoantibodies, and there is a connection between atherosclerosis and autoimmunity. However, the immunogenic trigger and the effects of the autoantibody response during atherosclerosis are not well understood. Here we performed high-throughput single-cell analysis of the atherosclerosis-associated antibody repertoire. Antibody gene sequencing of more than 1,700 B cells from atherogenic Ldlr and control mice identified 56 antibodies expressed by in-vivo-expanded clones of B lymphocytes in the context of atherosclerosis. One-third of the expanded antibodies were reactive against atherosclerotic plaques, indicating that various antigens in the lesion can trigger antibody responses. Deep proteomics analysis identified ALDH4A1, a mitochondrial dehydrogenase involved in proline metabolism, as a target antigen of one of these autoantibodies, A12. ALDH4A1 distribution is altered during atherosclerosis, and circulating ALDH4A1 is increased in mice and humans with atherosclerosis, supporting the potential use of ALDH4A1 as a disease biomarker. Infusion of A12 antibodies into Ldlr mice delayed plaque formation and reduced circulating free cholesterol and LDL, suggesting that anti-ALDH4A1 antibodies can protect against atherosclerosis progression and might have therapeutic potential in CVD.Ministerio de Economía y Competitividad (SVP-2014-068289); P.D. was supported by an AECC grant (AIO 2012, Ayudas a Investigadores en Oncología 2012); A.S.-B. is a Juan de la Cierva researcher (IJC2018-035279-I); I.M.-F. was a fellow of the research training program funded by Ministerio de Economía y Competitividad (SVP-2014-068216); and A.R.R. and J.V. are supported by Centro Nacional de Investigaciones Cardiovasculares (CNIC). The project leading to these results has received funding from la Caixa Banking Foundation under the project code HR17-00247 and from SAF2016-75511-R and PID2019-106773RB-I00 grants to A.R.R. (Plan Estatal de Investigación Científica y Técnica y de Innovación 2013–201
The zCOSMOS redshift survey : Influence of luminosity, mass and environment on the galaxy merger rate
The contribution of major mergers to galaxy mass assembly along cosmic time
is an important ingredient to the galaxy evolution scenario. We aim to measure
the evolution of the merger rate for both luminosity/mass selected galaxy
samples and investigate its dependence with the local environment. We use a
sample of 10644 spectroscopically observed galaxies from the zCOSMOS redshift
survey to identify pairs of galaxies destined to merge, using only pairs for
which the velocity difference and projected separation of both components with
a confirmed spectroscopic redshift indicate a high probability of merging. We
have identified 263 spectroscopically confirmed pairs with r_p^{max} = 100
h^{-1} kpc. We find that the density of mergers depends on luminosity/mass,
being higher for fainter/less massive galaxies, while the number of mergers a
galaxy will experience does not depends significantly on its intrinsic
luminosity but rather on its stellar mass. We find that the pair fraction and
merger rate increase with local galaxy density, a property observed up to
redshift z=1. We find that the dependence of the merger rate on the luminosity
or mass of galaxies is already present up to redshifts z=1, and that the
evolution of the volumetric merger rate of bright (massive) galaxies is
relatively flat with redshift with a mean value of 3*10^{-4} (8*10^{-5}
respectively) mergers h^3 Mpc^{-3} Gyr^{-1}. The dependence of the merger rate
with environment indicates that dense environments favors major merger events
as can be expected from the hierarchical scenario. The environment therefore
has a direct impact in shapping-up the mass function and its evolution
therefore plays an important role on the mass growth of galaxies along cosmic
time.Comment: submitted to A&A, 17 pages, 12 figure
Can cognitive enhancers reduce the risk of falls in older people with Mild Cognitive Impairment? A protocol for a randomised controlled double blind trial
<p>Abstract</p> <p>Background</p> <p>Older adults with cognitive problems have a higher risk of falls, at least twice that of cognitively normal older adults. The consequences of falls in this population are very serious: fallers with cognitive problems suffer more injuries due to falls and are approximately five times more likely to be admitted to institutional care. Although the mechanisms of increased fall risk in cognitively impaired people are not completely understood, it is known that impaired cognitive abilities can reduce attentional resource allocation while walking. Since cognitive enhancers, such as cholinesterase inhibitors, improve attention and executive function, we hypothesise that cognitive enhancers may reduce fall risk in elderly people in the early stages of cognitive decline by improving their gait and balance performance due to an enhancement in attention and executive function.</p> <p>Method/Design</p> <p>Double blinded randomized controlled trial with 6 months follow-up in 140 older individuals with Mild Cognitive Impairment (MCI). Participants will be randomized to the intervention group, receiving donepezil, and to the control group, receiving placebo. A block randomization by four and stratification based on fall history will be performed. Primary outcomes are improvements in gait velocity and reduction in gait variability. Secondary outcomes are changes in the balance confidence, balance sway, attention, executive function, and number of falls.</p> <p>Discussion</p> <p>By characterizing and understanding the effects of cognitive enhancers on fall risk in older adults with cognitive impairments, we will be able to pave the way for a new approach to fall prevention in this population. This RCT study will provide, for the first time, information regarding the effect of a medication designed to augment cognitive functioning have on the risk of falls in older adults with Mild Cognitive Impairment. We expect a significant reduction in the risk of falls in this vulnerable population as a function of the reduced gait variability achieved by treatment with cognitive enhancers. This study may contribute to a new approach to prevent and treat fall risk in seniors in early stages of dementia.</p> <p>Trial Registration</p> <p>The protocol for this study is registered with the Clinical Trials Registry, identifier number: NCT00934531 <url>http://www.clinicaltrials.gov</url></p
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