Search

La rápida acumulación de deuda pública en muchos países desde el comienzo de la crisis financiera de 2008, ha desembocado en elevados stocks de deuda en porcentaje del producto interior bruto (PIB). En el caso de España, este porcentaje ronda un 93,9٪ en 2013; ante esta situación, y dada la necesidad de una consolidación fiscal, en este artículo se utiliza un modelo de vectores autorregresivos sin restricciones para aportar evidencias sobre cuál es la mejor forma para realizar dicha consolidación. Entre los resultados destacan en primer lugar la existencia de una precedencia temporal de ingresos a gastos y en segundo lugar se obtiene que un aumento del tamaño del sector público, aun siendo sostenible la deuda pública, podría reducir el nivel de crecimiento real de la economía. Finalmente, se concluye que el mejor camino sería la reducción del gasto público en lugar del aumento de la recaudación impositiva

Conventional treatments on horticultural crops present a great lack of efficiency in applications and difficult penetration into dense crops. Horticultural sprayers should be able to undertake applications in a wide range of conditions, depending on the kind of crop, the pest and its location.The aim of this work is to analyse the efficiency of an air-assisted sprayer on artichoke (Cynara scolymus L.), a horticultural crop whose density makes penetration of the plant canopy difficult. Tests of an oriented jet, air-assisted sprayer for vegetables, with flexible ducts that lead the air towards the crop, have been performed in the field, using different positions of air outlets, types of nozzle and volume rates. Droplet population and coverage at different parts of the plant have been measured by means of image analysis. Generalized linear models have been used to model the sprayer performances.Fan nozzles showed the best response to air assistance, achieving the highest deposits, especially in lowest leaves and on the undersides.The flexibility of air ducts allows the outlets to be adjusted as required and a variable number of them to be employed on every row, with a resulting variation in the airflow. Better coverage and uniformity were achieved by directing three outlets per row.Any decrease in deposits due to volume reduction was not proportional to the decrease in the applied volume and can be compensated with an adjustment of chemical doses. [Copyright &y& Elsevier]

Both music and language are found in all known human societies, yet no studies have compared similarities and differences between song, speech, and instrumental music on a global scale. In this Registered Report, we analyzed two global datasets: (i) 300 annotated audio recordings representing matched sets of traditional songs, recited lyrics, conversational speech, and instrumental melodies from our 75 coauthors speaking 55 languages; and (ii) 418 previously published adult-directed song and speech recordings from 209 individuals speaking 16 languages. Of our six preregistered predictions, five were strongly supported: Relative to speech, songs use (i) higher pitch, (ii) slower temporal rate, and (iii) more stable pitches, while both songs and speech used similar (iv) pitch interval size and (v) timbral brightness. Exploratory analyses suggest that features vary along a "musi-linguistic" continuum when including instrumental melodies and recited lyrics. Our study provides strong empirical evidence of cross-cultural regularities in music and speech.

Music is present in every known society but varies from place to place. What, if anything, is universal to music cognition? We measured a signature of mental representations of rhythm in 39 participant groups in 15 countries, spanning urban societies and Indigenous populations. Listeners reproduced random 'seed' rhythms; their reproductions were fed back as the stimulus (as in the game of 'telephone'), such that their biases (the prior) could be estimated from the distribution of reproductions. Every tested group showed a sparse prior with peaks at integer-ratio rhythms. However, the importance of different integer ratios varied across groups, often reflecting local musical practices. Our results suggest a common feature of music cognition: discrete rhythm 'categories' at small-integer ratios. These discrete representations plausibly stabilize musical systems in the face of cultural transmission but interact with culture-specific traditions to yield the diversity that is evident when mental representations are probed across many cultures., (© 2024. The Author(s).)

Expressive communication in the arts often involves deviations from stylistic norms, which can increase the aesthetic evaluation of an artwork or performance. The detection and appreciation of such expressive deviations may be amplified by cultural familiarity and expertise of the observer. One form of expressive communication in music is playing "out of time," including asynchrony (deviations from synchrony between different instruments) and non-isochrony (deviations from equal spacing between subsequent note onsets or metric units). As previous research has provided somewhat conflicting perspectives on the degree to which deviations from synchrony and isochrony are aesthetically relevant, we aimed to shed new light on this topic by accounting for the effects of listeners' cultural familiarity and expertise. We manipulated (a)synchrony and (non-)isochrony separately in excerpts from three groove-based musical styles (jazz, candombe, and jembe), using timings from real performances. We recruited musician and non-musician participants (N = 176) from three countries (UK, Uruguay, and Mali), selected to vary in their prior experience of hearing and performing these three styles. Participants completed both an aesthetic preference rating task and a perceptual discrimination task for the stimuli. Our results indicate an overall preference toward synchrony in these styles, but culturally contingent, expertise-dependent preferences for deviations from isochrony. This suggests that temporal processing relies on mechanisms that vary in their dependence on low-level and high-level perception, and emphasizes the role of cultural familiarity and expertise in shaping aesthetic preferences., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

New chiral tetranuclear square-like homo- and heterometallamacrocycles containing allyl-palladium and either {Pd(P-P)*} or {Pt(P-P)*} optically pure moieties (P-P* = (2S,3S)- O -isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphanyl)butane (( S , S )-DIOP) and (2 S ,4 S )-2,4-bis(diphenylphosphanyl)pentane (( S , S )-BDPP)) have been obtained by the self-assembly of [Pd(η 3 -2-Me-C 3 H 4 )(4-PPh 2 py) 2 ] + and [M(P-P)*(H 2 O) 2 ] 2+ building blocks in a 1 : 1 molar ratio. The supramolecular assemblies thus prepared [{Pd(η 3 -2-Me-C 3 H 4 )} 2 (4-PPh 2 py) 4 {M(P-P)*} 2 ](CF 3 SO 3 ) 6 (M = Pd, Pt) have been fully characterised by multinuclear NMR spectroscopy and MS spectrometry. The structures display remarkable differences on their dynamic behaviour in solution that depend on the lability and thermodynamic strength of M-py bonds. The structural characteristics of the new metallamacrocyles obtained have also been unambiguously established by XRD analysis. The architectures have been assayed as catalytic precursors in the asymmetric allylic alkylation reaction.

The synthesis via phosphine-boranes of 13 new optically pure P-stereogenic diarylphosphines P(Het)PhR (Het = 4-dibenzofuranyl (DBF), 4-dibenzothiophenyl (DBT), 4-dibenzothiophenyl-S,S-dioxide (DBTO2) and 1-thianthrenyl (TA); R = OMe, Me, i-Pr, Fc (ferrocenyl)) following the Jugé-Stephan method is described. The ligands were designed with the aim of having a heteroatom in a position capable of interacting with a metal upon coordination. The ligands and their precursors have been fully characterised, including the determination of two crystal structures of phosphine-boranes. Ru neutral complexes of the type [RuCl2(η(6)-arene)(κP-P)] (arene = p-cymene and methyl benzoate) have been prepared and characterised, including three crystal structure determinations. Treatment of solutions of the complexes with TlPF6 allowed the preparation of well-defined cationic complexes [RuCl(η(6)-arene)(κ(2)P,S-P)]PF6 for DBT- and TA-based phosphines. The complexes possess a stereogenic Ru atom and in most of the cases they are present as a single isomer in solution. All the Ru complexes have been used in the asymmetric transfer hydrogenation of acetophenone in refluxing 2-propanol, with good activities and up to 70% ee.

The square-like homo- and heterometallamacrocycles [{Pd(η(3) -2-Me-C3 H4 )(L(n) )2 }2 {M(dppp)}2 ](CF3 SO3 )6 (dppp=1,3-bis(diphenylphosphino)propane) and [{Pd(η(3) -2-Me-C3 H4 )(L(1) )2 }2 {M(PPh3 )2 }2 ](CF3 SO3 )6 [py=pyridine, M=Pd, Pt, L(n=) 4-PPh2 py (L(1) ), 4-C6 F4 PPh2 py (L(2) )] containing allyl corners were synthesised by antisymbiotic self-assembly of the different palladium and platinum metallic corners and the ambidentate N,P ligands. All the synthesised assemblies displayed a complex dynamic behaviour in solution, the rate of which is found to be dependent on the electronic and/or steric nature of the different building blocks. A kinetico-mechanistic study by NMR line shape analysis of the dynamics of some of these assemblies was undertaken in order to determine the corresponding thermal activation parameters. Both an enhanced thermodynamic stability and slower dynamics were observed for platinum-pyridine-containing species when compared with their palladium analogues. Time-dependent NMR spectroscopy in combination with ESI mass spectrometry was used to study the exchange between the assemblies and their building blocks, as well as that occurring between different metallamacrocycles. Preliminary studies were carried out on the activity of some of the metallamacrocyclic compounds as catalytic precursors in the allylic substitution reaction, and the results compared with that of the monometallic allylic corner [Pd(η(3) -2-Me-C3 H4 )(L(1) )2 ](+) ., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reaction of a series of phosphanyl-terminated carbosilane dendrimers displaying only one phosphorus ligand per arm with [RuCl(2)(p-cymene)](2) resulted in the grafting of RuCl(p-cymene) moieties on the periphery of the dendrimer. In these species, the chloride ligand is easily displaced by the organic bases pyridine, 4-cyanopyridine and 4,4[prime or minute]-bipyridine to afford new cationic metallodendrimers. NMR studies have confirmed the chirality of the ruthenium centre. The species containing 4,4[prime or minute]-bipyridine reacts through the uncoordinated pyridyl nitrogen with a new equivalent of [RuCl(2)(p-cymene)](2) or [RhCl(CO)(2)](2) to lead to homo- or hetero-bimetallic layer-containing dendrimeric systems. The ruthenodendrimers were tested as catalysts in the transfer hydrogenation of cyclohexanone by propan-2-ol and their activity compared with that of some analogous mononuclear ruthenium(ii) complexes.

New families of enantiopure bis(oxazolines) with 4,5-trans (5 a-g) or 4,5-cis (6 c) stereochemistry at the individual rings have been prepared in high yield. Their eta(3)-allyl palladium complexes (8 a-g, 9 c and 10) have been used as catalytic precursors in allylic alkylation reactions with excellent enantioselectivities (up to 96 %) for the trans oxazoline derivatives, while Pd/6 c system was inactive. NMR studies on palladium eta(3)-1,3-diphenylallyl intermediates (11 a, c and e) showed the presence of syn/syn- and syn/anti-allyl isomers in solution; this resembles the first example of eta(3)-eta(1)-eta(3) isomerism in Pd allylic complexes containing bis(oxazolines) derived from malonic acid.

The intramolecular transfer of the allyl group of functionalized allyl aryl ethers to an aldehyde group in the presence of Ni0 complexes was studied from chemical, electrochemical and theoretical points of view. The chemical reaction involves the addition of Ni0 to the allyl ether followed by stoichiometric allylation. The electrochemical process is catalytic in nickel and involves the reduction of intermediate eta3-allylnickel(II) complexes.