2,888 research outputs found
Financiación pública y emprendimiento: comportamientos y heterogeneidad regional de las pequeñas y medianas empresas
The existence of restrictions for small- and medium-sized enterprises (SMEs) to access long-term credit has led governments to establish institutional systems to facilitate such access and reduce the cost of credit, with the condition that its feasibility is justified (and assessed) and there are no distortions as regards competition. Very few empirical in-depth studies exist regarding this field of academic research, and scarce attention has been paid from a regional perspective. Due to the characteristics of the business structures in the different regions, as well
as the existence of agglomeration economies and the regional dispersion of the entrepreneurship rate, this paper analyses the effects of the productive financing support model, provided by the Government of Spain, through the Instituto de Crédito Oficial (ICO) [Official Credit Institute], on the behaviours and performances of the beneficiary companies. In the last decade, this source of financing has assigned 30,000 million euro. The results show the general acceptance of this policy due to its adaptation to the interests of the companies and its contribution to the improvement of the economic-financial efficiency indicators. Regionally, no substantial differences have been observed, but the results of this research show a greater contribution to the dynamism of the more progressive regions.La generalizada aceptación de la existencia de restricciones al acceso al crédito a largo plazo por parte de las pequeñas y medianas empresas (Pyme), ha inducido a los gobiernos al establecimiento de sistemas institucionales que faciliten dicho
acceso y abaraten el coste del crédito, siempre que pueda justificarse (y evaluarse) su viabilidad y no introduzcan distorsiones en la competencia. Abundantes estudios han
profundizado en esta vía de investigación académica, aunque apenas han particularizado la perspectiva regional. Debido a las distintas características que presenta la estructura empresarial entre las regiones, así como a la existencia de economías de
aglomeración y a la dispersión regional de la tasa de empresarialidad, en este trabajo se analiza la incidencia del modelo de apoyo a la financiación productiva, proporcionada
por el gobierno de España, a través del Instituto de Crédito Oficial (ICO), en los comportamientos y desempeños de las empresas beneficiarias. Esta línea de financiación, de intermediación bancaria, ha destinado en la última década casi 30.000 millones
de euros. Los resultados arrojan evidencias de la aceptación generalizada de esta política por su adecuación a los intereses de las empresas y por su contribución a la mejora de sus indicadores de eficiencia económico-financiera. Regionalmente, no se
observan importantes disimilitudes, pero la investigación detecta una mayor contribución al dinamismo de las regiones más avanzadas
Pattern classification with missing values using multitask learning
In many real-life applications it is important
to know how to deal with missing data (incomplete feature
vectors). The ability of handling missing data has become a
fundamental requirement for pattern classification because inappropriate
treatment of missing data may cause large errors or
false results on classification. A novel effective neural network
is proposed to handle missing values in incomplete patterns
with Multitask Learning (MTL). In our approach, a MTL
neural network learns in parallel the classification task and
the different tasks associated to incomplete features. During the
MTL process, missing values are estimated or imputed. Missing
data imputation is guided and oriented by the classification task,
i.e., imputed values are those that contribute to improve the
learning. We prove the robustness of this MTL neural network
for handling missing values in classification problems from UCI
database.This work will stimulate future works in many directions.
Some of them are using different error functions (crossentropy
error in discrete tasks, and sum-of-squares error
in continuous tasks), adding an EM-model to probability
density estimation into the proposed MTL scheme, setting
the number of neurons in each subnetwork dynamically
using constructive learning, an extensive comparison
with other imputation methods, to use this procedure in
regression problems, and extending the proposed method
to different machines, e.g., Support Vector Machines (SVM)
On -Frobenius of affine semigroups
The aim of this paper is to study the -Frobenius vector of affine
semigroups ; that is, the maximum element, with respect
to a graded monomial order, with at most factorizations in . We produce
several algorithms to compute these vectors. Finally, we study how the
-Frobenius vectors behave when considering gluings of with
New World Diapriinae.
138 p. : ill. ; 26 cm.Includes bibliographical references (p. 122-125) and index.The subfamily Diapriinae (Diapriidae: Proctotrupoidea) in the New World is reviewed at the supra specific level. Three tribes and 52 genera are recognized. Sixteen new genera are proposed: Apopria (Diapriini), Avoca (Diapriini), Chilomicrus (Spilomicrini), Cruzium (Diapriini), Doddius (Spilomicrini), Eladio (Diapriini), Epomium (Spilomicrini), Ferrugenus (Spilomicrini), Hansona (Diapriini), Leucopria (Diapriini), Mimopriella (Diapriini), Omopria (Diapriini), Ortona (Psilini), Peckidium (incertae sedis) Psychopria (Diapriini), and Turripria (Diapriini). The following new species are described: Apopria coveri [female] (USA), Asolenopsia gibba [female] (Costa Rica), Avoca collaris [female] (USA), Chilomicrus pecki [male] (Chile), Cruzium amphorale [female] (Costa Rica), Eladio cruzi [female] (Costa Rica), Epomium cicatrix [female] (Chile), Ferrugenus chilensis [female] (Chile), Hansona pauli [female] (Costa Rica), Leucopria cylindricornis [female] (Ecuador, Costa Rica), Omopria brevipalpis [female] (Brazil), Ortona hansoni [female] (Costa Rica), Peckidium enigmaticum [female] (Antilles, Central and South America, West Africa, Philippines), Psychopria hoguei [male] (Costa Rica), Turripria woldai [female] (Panama). New generic synonymies are proposed: Acanthopria Ashmead (= Adelioneiva Fischer), Asolenopria Kieffer (= Euplacopria Ferrière), Bruchopria Kieffer (= Aulatopria Brèthes), Doliopria Kieffer (= Martinica Risbec), Megaplastopria Ashmead (= Xyalopria Kieffer), Notoxoides Ashmead (= Psilogasteroides Brèthes), Pentapria Kieffer (= Antipapria Fabritius, Bakeria Kieffer, Plutopria Kieffer, Spilomicrinus Ogloblin), Spilomicrus Westwood (= Hoplopria Ashmead, Linkiola Kieffer), Szelenyiopria Fabritius (= Gymnopria Loiácono). New combinations are proposed: Aulatopria tucumana Brèthes to Bruchopria, Bakeria rugosa Dodd to Doddius, Gymnopria lucens Loiácono to Szelenyiopria, Mimopria pentatoma Borgmeier and Mimopria splendens Borgmeier to Mimopriella, and Xanthopria nitida Brues to Acanthopria. The 52 genera are keyed (keys in both English and Spanish); for each genus the synonymies, diagnoses, descriptions, recognition and relationships, distribution, and biology are given. Twelve plates with 107 figures are included
Imine-palladacycles as phosphine-free precatalysts for low temperature Suzuki-Miyaura synthesis of nucleoside analogues in aqueous media
The synthesis and characterization of new water-soluble dinuclear palladacycles of the general formula [{Pd(R-C^N-SO3Na)(μ-AcO)}2] (R = H (1), OMe (2), Cl (3)) incorporating an ortho-metalated sodium 4-(N-benzylideneamino)benzenesulfonate moiety is reported. These complexes have been revealed to be excellent phosphine-free catalysts for the synthesis of functionalized nucleoside analogues involving a low-temperature Suzuki–Miyaura coupling of 5-iodo-2′-deoxyuridine with different arylboronic acids in neat water. The potential of 1–3 as synthetic precursors was also tested, and bridging acetates were cleaved by reaction with neutral PPh3, yielding the corresponding mononuclear derivatives [Pd(R-C^N-SO3Na)(AcO)(PPh3)] (R = H (4), MeO (5), Cl (6)). Analytical and spectroscopic techniques confirmed the proposed formulas and reactivities reported for complexes 1–6. Structural characterization by X-ray diffraction of single crystals grown from samples of 4 and 6 produced the unexpected but valuable crystallization-mediated compounds 4cm and 6cm that also supported the results presented here.This work has been partially supported by RTI2018-098233-B-C21 (MICINN) and
20790/PI/18 (Fundación SENECA CARM) grants. A.R.K would like to acknowledge
SERB for EMR grant (EMR/2016/005439). Professor Gregorio Sánchez, who recently
passed away, is gratefully acknowledged for his contribution to this work and his wise
and continuous advise and suppor
Cortistain is expressed in a distinct subset of cortical interneurons
Cortistatin is a presumptive neuropeptide that shares 11 of its 14 amino acids with somatostatin. In contrast to somatostatin, administration of cortistatin into the rat brain ventricles specifically enhances slow wave sleep, apparently by antagonizing the effects of acetylcholine on cortical excitability. Here we show that preprocortistatin mRNA is expressed in a subset of GABAergic cells in the cortex and hippocampus that partially overlap with those containing somatostatin. A significant percentage of cortistatin-positive neurons is also positive for parvalbumin. In contrast, no colocalization was found between cortistatin and calretinin, cholecystokinin, or vasoactive intestinal peptide. During development there is a transient increase in cortistatin-expressing cells in the second postnatal week in all cortical areas and in the dentate gyrus. A transient expression of preprocortistatin mRNA in the hilar region at P16 is paralleled by electrophysiological changes in dentate granule cells. Together, these observations suggest mechanisms by which cortistatin may regulate cortical activity
Electrosynthesis of 2,3-butanediol and methyl ethyl ketone from acetoin in flow cells
Acetoin could shortly become a platform molecule due to current progress in fermentation technology, the megatrend for
shifting from an oil-based economy to one based on biomass, the quest for green manufacturing processes and its two
highly reactive carbonyl and hydroxyl moieties. In this paper, the successful electro-conversion of acetoin into two
valuable chemicals, 2,3-butandiol (2,3-BD) and methyl ethyl ketone (MEK), at constant electrical current in aqueous
phase at room temperature using both divided and undivided 20 cm2 filter-press flow cells under experimental conditions
suitable for industrial production is reported. Cathode material is the key parameter to drive the electroreduction towards
one or another chemical. 2,3-BD is the major chemical produced by electrohydrogenation when low hydrogen overvoltage
cathodes, such as Pt and Ni, of high surface area obtained by PVD coating on a carbon gas diffusion layer are used, while
MEK is the principal product produced by electrohydrogenolysis when high hydrogen overvoltage cathodes, such as
graphite, Pb and Cd foils, are employed. 2,3-BD and MEK can be obtained, respectively, in 92.8% and 85.7%
selectivities, 71.7% and 80.4% current efficiencies, with 1.21 and 1.08 kg.h-1.m-2 productivities and power consumptions
of 2.94 and 4.1 kWh.kg-1 using undivided cells and aqueous K2HPO4 electrolysis media at pHs of 3.6 and 5.5. The
reported electroconversion of acetoin is highly flexible because 2,3-BD and MEK can be produced by changing just the
cathode but using the same cell, with the same electrolyte at the same current density
Improving the tribological performance of a biodegradable lubricant adding graphene nanoplatelets as additives
This research is based on the investigation of the tribological properties of a biodegradable polymeric ester lubricant (BIOE) additivated with two different pristine graphene nanoplatelets (GnPs), named as GnP7 and GnP40. These GnPs have lateral sizes of 7 and 40 μm, and thickness of 3 and 10 nm, respectively. Four different nanoadditive loadings: 0.015, 0.035, 0.055 and 0.075 wt% have been used. Stability of nanolubricants has been investigated using the visual control and the refractive index evolution during time, revealing a slightly better stability for the nanolubricants formulated with the largest lateral size graphene nanoplatelets (GnP40). The influence of the thickness and lateral size of these carbon-based nanoadditives on the antifriction and antiwear capabilities of BIOE is analysed. For this purpose, rotational friction tests were taken with the eight nanolubricants under a 20 N working load and 340 m sliding distance. All nanolubricants showed friction coefficients and worn area lower than those previously reported for the unadditivated BIOE. As regards friction, the ideal loading for both GnPs was 0.055 wt% GnP, being the best anti-friction behaviour obtained using GnP40 as additive (up to 26% reduction), whereas the 0.055 wt% GnP7/BIOE nanolubricant leads to the best anti-wear capability with wear reductions up to 56%. Finally, from Raman microscopy and roughness assessments on the worn surfaces, it can be determined that the good tribological performance of nanolubricants is owing to the protective film formation and surface repairing mechanismThis research was supported by the “Ministerio de Ciencia, Innovación y Universidades” (Spain) and the FEDER program through the ENE2017-86425-C2-1/2-R project and by Xunta de Galicia (ED431C 2020/10). Authors would like to thank Verkol Lubricantes and Avanzare Innovacion Tecnologica S.L. for providing the BIOE base oil and pristine graphene nanoplatelets, respectively. Authors would like also to thank the help of RIAIDT-USC analytical facilities. M.J.G.G. and J.I.P. are grateful for the support of the Xunta de Galicia for the postdoctoral (reference ED481B-2019-015) and predoctoral fellowship grantsS
New models involving quantum chemical parameters for assessing the chromatographic retention process
.Knowledge about the theoretical relationship between the analyte properties and the critical chromatographic parameters is mandatory for a better interpretation of the separation mechanism and a more leisurely development of quantitative studies. In a preliminary stage of this work, we introduce the Gumbel distribution, the extreme value distribution type-I widely used in other fields, as a novel tool for modelling the chromatographic peak shape. Further, we develop mathematical models to evaluate the effect of the experimental variables and various quantum parameters on the chromatographic indices, such as the retention time, capacity factor, asymmetry factor, tailing factor and number of theoretical plates. Finally, we propose a mechanistic behaviour for the chromatographic separation process based on the structure-retention relationship of fifteen selected drugs involving several molecular quantum parametersS
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