929 research outputs found
Genera of curves on a very general surface in
In this paper we consider the question of determining the geometric genera of
irreducible curves lying on a very general surface of degree at least 5
in (the cases are well known).
We introduce the set of all non-negative integers which are not
realized as geometric genera of irreducible curves on . We prove that
is finite and, in particular, that . The set
is the union of finitely many disjoint and separated integer
intervals. The first of them, according to a theorem of Xu, is . We show that the next one is for all .Comment: 16 page
Entrepreneurial approach for open innovation: opening new opportunities, mapping knowledge and highlighting gaps
Purpose Since the first definition of open innovation (OI), the indivisible relationship between this concept and entrepreneurship was undeniable. However, the exact mechanisms by which an entrepreneurial approach may benefit OI processes and vice versa are not yet fully understood. The study aims to offer an accurate map of the knowledge evolution of the OI-entrepreneurship relationship and interesting gaps to be filled in the future. Design/methodology/approach The study adopted a bibliometric analysis, coupled with a systematic literature review performed over a data set of 106 peer-reviewed articles published from 2005 to 2020 to identify thematic clusters. Findings The results show five thematic clusters: entrepreneurial opportunities, organisational opportunities, strategic partnership opportunities, institutional opportunities and digital opportunities for OI. Investigating each of them, the authors created a framework that highlights future avenues for further developing the topic. Originality/value This study is the first of its kind to systematise, analyse and critically interpret the literature concerned with the topic of the OI-entrepreneurship
Changes in volatiles of olive tree Olea europaea according to season and foliar fertilization
In the present study, four foliar fertilizers (FF1, FF2, FF3 and FF4) were separately sprayed on Chemlali olive trees at different moments of the vegetative cycle. FF1 (rich in nitrogen) was applied during the vegetation stage (Last January-February) at a dose of 5 L/ha per spray (three sprays per season). FF2 (rich in boron, magnesium and sulphur), FF3 (rich in phosphorus and potassium) and FF4 (rich in phosphorus and calcium) were applied respectively during the stages of flowering (Last March-April), fruit growth (July-August) and ripening (October-November), at a dose of 3 L/ha per spray (three sprays per season for each fertilizer).The volatile fraction was analysed by GC-MS, 46 volatile compounds were identified and their amount were expressed as relative abundance (%). In a general view, the most abundant volatiles in Chemlali olive leaves across the vegetative cycle were (E)-2-hexenal, nonanal, (E)-β-damascenone, 3-ethenyl pyridine and β-caryophyllene. The levels of these main compounds and the general composition of the volatile fraction varied significantly through season.The volatile levels were mainly affected by the two foliar fertilizers enriched with nitrogen and Boron respectively. The most affected volatiles were (E)-2-hexenal, nonanal, 3-ethenyl pyridine, (E,E)-α-farnesene, and (E)-nerolidol. Less impact was noticed after the use of the other foliar fertilizers.Our study is the first investigation bringing data about the variation of leaf volatile profile of Chemlali cultivar across a vegetative cycle and showing the impact of nutrient foliar sprays on olive leaf volatile
Estructura flexible y fina formada por una red de cuerdas, hilos u otras fibras: Espacios Culturales Alternativos y Autogestionados de Madrid.
La autogestión de espacios alternativos culturales es un modo de hacer y organizarse. Generalmente promovidas por los propios artistas que no están de acuerdo con el sistema impuesto de las industrias culturales e institucionales y funcionan de forma horizontal dentro del circuito del arte. La permanencia de dichos espacios es costosa ya que no cuentan con un flujo económico abundante y tienen poca contención por parte del gobierno, lo cual dificulta la continuidad de estas propuestas. Por ello es que utilizan estrategias para sostenerse en el tiempo a la vez que generan una especie de malla o red que los vincula entre sÃ. Esto les permite trabajar y sostenerse mutuamente y continuar su permanencia. Hoy podemos encontrar cada vez más espacios culturales alternativos que ejercen esta práctica de la autogestión
Chemical composition and biological activities of Daucus aureus essential oils from Eastern Algeria
The aim of this study was to investigate the chemical composition of the essential oils of three populations of Daucus aureus from three sites in Eastern Algeria
(Setif, Constantine and Oum Elbouaghi) and to test their antibacterial and antioxidant activities. The essential oils were obtained by hydrodistillation and analyzed
by GC and GC/MS. The major components were sabinene (30.6% and 36.2%), n-nonane (8.0% and 7.9%), α-pinene (5.5% and 6.3%) and 4-terpineol (4.4% and
6.0%) in D. aureus from Setif and Constantine populations essential oils, respectively; whereas, α-pinene (19.4%), β-pinene (12.0%) and p-cymene (12.2%) were
the major components in Oum Elbouaghi essential oil population. The chemical compositions of D. aureus from Eastern Algeria are markedly different from those
from Western Algeria, and likely represent new chemotypes. The antimicrobial activity of the essential oils was evaluated against four bacteria and one fungus,
using the disc-diffusion method and minimal inhibitory concentration (MIC), whereas, the antioxidant activity of the essential oils was evaluated using the DPPH
test. The results showed that the oils have an antimicrobial activity against the microorganisms tested, with minimal inhibitory concentration (MIC) values between
0.97 and 3.23 mg/mL and weaker antioxidant and DPPH radical scavenging activities were found in comparison to butylated hydroxyl toluene (BHT)
Annealing post-drawn polycaprolactone (PCL) nanofibers optimizes crystallinity and molecular alignment and enhances mechanical properties and drug release profiles
Post-drawn PCL nanofibers can be molecularly tuned to have a variety of mechanical properties and drug release profiles depending on the temperature and time of annealing, which has implications for regenerative medicine and drug delivery applications. Post-drawing polycaprolactone (PCL) nanofibers has previously been demonstrated to drastically increase their mechanical properties. Here the effects of annealing on post-drawn PCL nanofibers are characterized. It is shown that room temperature storage and in vivo temperatures increase crystallinity significantly on the order of weeks, and that high temperature annealing near melt significantly increases crystallinity and molecular orientation on the order of minutes. The kinetics of crystallization were assessed using an anneal and quench approach. High temperature annealing also increased the ultimate tensile strength and toughness of the fibers and changed the release profile of a model drug absorbed in PCL nanofibers from first-order to zero-order kinetics
Scutellaria caucasica A. Ham.: Morphological features and headspace characterization
In the context of a wide research project, a micromorphological and phytochemical characterization was performed on the vegetative and reproductive organs of Scutellaria caucasica A. Ham. (Lamiaceae), cultivated at the Ghirardi Botanic Garden (Toscolano Maderno, BS, Lombardy, Italy). The morphological survey revealed the presence of both non-glandular and glandular trichomes. The latter belonged to three different morphotypes: peltate, short-stalked and long-stalked capitate. Histochemical assays demonstrated that the terpenes biosynthesis mainly took place in the peltates, while short-stalked capitates secreted only polysaccharides; the long-stalked ones mainly produced polysaccharides, coupled with terpene and polyphenolic fractions. An element of novelty was represented by the characterization of the VOC emission profile. Leaves and flowers showed differences in their emissions: the floral profile had a higher number of compounds than that of the leaves (37 vs 29), with a higher heterogeneity. The almost totality of the leaf profile was characterized by sesquiterpene hydrocarbons (98.8 %), while the flowers presented a more varied composition, with sesquiterpene hydrocarbons (87.2 %), monoterpenes (10.4 % oxygenated, 1.8 % hydrocarbons) and non-terpenes derivatives (0.6 %). The most abundant compounds were \u3b3-muurolene (42.6 %) and \u3b2-caryophyllene (35.0 %) in the leaves and in the flowers, respectively. In the flower headspace, 16 exclusive compounds were identified, among which germacrene D (31.7 %) dominated; leaves had 8 exclusive compounds, with valencene (1.8 %) as the most represented one. 21 common compounds were revealed: \u3b2-caryophyllene (34.1 % leaves; 35.0 % flowers), \u3b1-humulene (3.0 % leaves; 3.1 % flowers), alloaromadendrene (2.4 % leaves; 1.0 % flowers), \u3b1-copaene (2.1 % leaves; 2.7 % flowers) and \u3b2-copaene (2.2 % leaves; 1.5 % flowers) were the most abundant ones. \u3b3-Muurolene relative abundances (42.6 % leaves; 0.7 % flowers) were very different between the two profiles. Overall, this work represented the first multidisciplinary study on S. caucasica, combining a scientific research approach with the policies of the Open Science
Validating multi-photon quantum interference with finite data
Multi-particle interference is a key resource for quantum information processing, as exemplified by Boson Sampling. Hence, given its fragile nature, an essential desideratum is a solid and reliable framework for its validation. However, while several protocols have been introduced to this end, the approach is still fragmented and fails to build a big picture for future developments. In this work, we propose an operational approach to validation that encompasses and strengthens the state of the art for these protocols. To this end, we consider the Bayesian hypothesis testing and the statistical benchmark as most favorable protocols for small- and large-scale applications, respectively. We numerically investigate their operation with finite sample size, extending previous tests to larger dimensions, and against two adversarial algorithms for classical simulation: the mean-field sampler and the metropolized independent sampler. To evidence the actual need for refined validation techniques, we show how the assessment of numerically simulated data depends on the available sample size, as well as on the internal hyper-parameters and other practically relevant constraints. Our analyses provide general insights into the challenge of validation, and can inspire the design of algorithms with a measurable quantum advantage
Investigación preliminar sobre los posibles efectos del tratamiento con arcilla mineral aplicado a aceites producidos a partir de aceitunas: enfoque sobre la eliminación de humedad y cambios en la composición
In this preliminary study, two non-filtered virgin olive oils (one freshly produced VOO-N; one VOO-O stored for one year) were subjected to moisture removal with mineral clay (raw or activated) and analyses were performed to attest possible effects on the quality of the product. The results demonstrated that the treatment of oil with mineral clay at 36-38 °C had no negative effect on the basic quality parameters or on the volatile comound profile. On the other hand, a significant decrease in the water amount as well as in pigments was observed in the samples subjected to this kind of treatment, in particular with raw clay. Regarding the colour measurement, the lightness (L) as well as the consumers’ acceptability exhibited a marked increase when oils were treated with raw clay.En este estudio preliminar, dos aceites de oliva vÃrgenes no filtrados (uno VOO-N recién producido y el otro, VOO-O almacenado durante un año) fueron sometidos a la eliminación del contenido de humedad con arcilla mineral (cruda o activada) y se realizaron análisis para atestiguar posibles efectos sobre la calidad del producto. Los resultados demostraron que el tratamiento del aceite con arcilla mineral, realizado a 36-38 °C, no tuvo consecuencias negativas en los parámetros básicos de calidad y en el perfil de los compuestos volátiles. Por otro lado, se observó una disminución significativa en la cantidad de agua y en los pigmentos en las muestras sometidas a este tipo de tratamiento, en particular con arcilla cruda. Con respecto a la medida del color, luminosidad (L) y aceptabilidad de los consumidores mostraron un aumento notable cuando los aceites se trataron con arcilla cruda
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