Search

Dielectric Assist Accelerating (DAA) structures based on ultralow-loss ceramic are being studied as an alternative to conventional disk-loaded copper cavities. This accelerating structure consists of dielectric disks with irises arranged periodically in metallic structures working under the TM02-π mode. In this paper, the numerical design of an S-band DAA structure for low beta particles, such as protons or carbon ions used for Hadrontherapy treatments, is shown. Four dielectric materials with different permittivity and loss tangent are studied as well as different particle velocities. Through optimization, a design that concentrates most of the RF power in the vacuum space near the beam axis is obtained, leading to a significant reduction of power loss on the metallic walls. This allows to fabricate cavities with an extremely high quality factor, over 100,000, and shunt impedance over 300 MΩ/m at room temperature. During the numerical study, the design optimization has been improved by adjusting some of the cell parameters in order to both increase the shunt impedance and reduce the peak electric field in certain locations of the cavity, which can lead to instabilities in its normal functioning.

The objective of this work is the evaluation of the risk of suffering a multipactor discharge in an S-band dielectric-assist accelerating (DAA) structure for a compact low-energy linear particle accelerator dedicated to hadrontherapy treatments. A DAA structure consists of ultra-low loss dielectric cylinders and disks with irises which are periodically arranged in a metallic enclosure, with the advantage of having an extremely high quality factor and very high shunt impedance at room temperature, and it is therefore proposed as a potential alternative to conventional disk-loaded copper structures. However, it has been observed that these structures suffer from multipactor discharges. In fact, multipactor is one of the main problems of these devices, as it limits the maximum accelerating gradient. Because of this, the analysis of multipactor risk in the early design steps of DAA cavities is crucial to ensure the correct performance of the device after fabrication. In this paper, we present a comprehensive and detailed study of multipactor in our DAA design through numerical simulations performed with an in-house developed code based on the Monte–Carlo method. The phenomenology of the multipactor (resonant electron trajectories, electron flight time between impacts, etc.) is described in detail for different values of the accelerating gradient. It has been found that in these structures an ultra-fast non-resonant multipactor appears, which is different from the types of multipactor theoretically studied in the scientific literature. In addition, the effect of several low electron emission coatings on the multipactor threshold is investigated. Furthermore, a novel design based on the modification of the DAA cell geometry for multipactor mitigation is introduced, which shows a significant increase in the accelerating gradient handling capabilities of our prototype.

Abstract Background Mandrake (Mandragora spp.) is one of the most famous medicinal plant in western cultures since Biblical times and throughout written history. In many cultures, mandrake is related to magic and witchcraft, which is said to have a psychosomatic effect (especially when mandrake contains narcotic compounds) in addition to the pharmacological influence, as occurs with other narcotic magical plants. Due to its unique properties and related myths, it is not surprising that this plant has many names in many languages. Methods This paper presents an attempt to reconstruct the historical, ethnobotanical, and folkloristic roots of 292 vernacular names of Mandragora spp. in forty-one languages. We used the plant’s morphological data, philology, myths and legends, medicinal properties and uses, as well as historical evidence and folkloric data, to explain meaning, origin, migration, and history of the plant’s names. Results The names were classified into the following main categories: Derivatives of mandragora (19 languages), alraun (7) and of yabroukh (5). The salient groups of the plant’s vernacular names are related to: Anthropomorphism (33 names in 13 languages); Similarity to other plants (28/9); Supernatural agents (28/9); Narcotic effects (21/8); Leaves, fruits, and seeds (21/8); Aphrodisiac properties (17/10); Use of a dog (15/9); Gallows (14/5); Black magic, sorcery, witchcraft (13/8), and Medicinal use (11/7). Conclusions This frequency distribution of the mandrake’s vernacular names reflects its widespread reputation as related to the doctrine of signatures, beliefs in its supernatural, natural, and mythic powers, and to a lesser extent, its uses in magic and medicine. A spatiotemporal analysis of the mandrake’s names supports the old idea that the pulling ceremonies for this plant originated in the Near East and that various other myths related to this plant may have originated in different places and periods.

Seseli farrenyi (Apiaceae) is an extremely narrow endemic plant, which is considered as one of the species of most conservation concern in Catalonia (NW Mediterranean Basin). Given the accelerated fragmentation and reduction of population size (of over 90%), the environmental agency of Catalonia is currently preparing a recovery plan that includes reinforcements of the extant populations. The present study is aimed at providing the necessary knowledge to carry out genetically-informed translocations, by using microsatellites as genetic markers. Fourteen microsatellites have been specifically developed for S. farrenyi, of which nine have been used. Besides the extant natural populations, the three ex situ collections that are known to exist of this species have also been studied, as they would be the donor sources for translocation activities. Our main finding is that levels of genetic diversity in the natural populations of S. farrenyi are still high (He = 0.605), most likely as a result of a predominantly outcrossing mating system in combination with the limited time elapsed since the population decline. However, population fragmentation is showing the first genetic signs, as the values of genetic differentiation are relatively high, and two well-differentiated genetic lineages have been found even in such a narrow geographic range. These genetic results provide important information when designing conservation management measures.

In recent years, there has been a rapid growth in the implementation of Blended Learning as a teaching modality, as well as in the research of methodologies related to improvement in learning outcomes. However, in non-Anglo-Saxon universities, research on the institutional policy related to this type of teaching is scarce. In two earlier studies, the authors have published previous outcomes on this modality, at a general level, referring to 20 European universities, as well as an in-depth study at the University of Barcelona. This research analyzes the current implementation of Blended Learning in the twelve universities integrated in the university system of Catalonia (NE Spain) in order to identify the key elements that determine the strategic adoption of this modality. With this aim, Thus, semi-structured surveys were carried out to the twelve vice-rectors responsible for educational policy in each university. This article describes the current state of the Blended Learning in the Catalan university system and it is analyzed in comparison to the data of six years ago. It is evident, on the one hand, as at the grade level, the increase has not been expected in relation to previous expectations. On the other hand, it becomes clear the conceptual change of the formal blended teaching, with the accreditation of academic authorities, towards new, more flexible approaches to hybrid or combined learning.

Protection and management of closely related endangered species and subspecies at a very narrow regional scale is the origin of multiple dysfunctional conservation decisions. These include artificially increased IUCN risk assessment categories and derived consequences: poor effectiveness in allocating public and private funds or repeat of unnecessary actions/facilities. Data provided by the revisited study of a group of W Mediterranean larkspurs (Delphinium ser. Fissa), including new data on demography, niche modeling, genetic diversity and phylogeography, contributed to a new and wider analysis of causes of threat. Although current IUCN Red List regulations did not allow for assessments at levels higher than a specific rank, scientific information suggests that in some cases this could be a better approach for sound scientifically-based biodiversity conservation planning and action. Keywords: Biodiversity conservation, Conservation genetics, Delphinium ser. Fissa, Allozymes, cpDNA, Chromosome numbers

This paper provides an overview of the last 40 years of use, and in many cases abuse, of the natural resources in Catalonia, a country that is representative of European countries in general, and especially those in the Mediterranean region. It analyses the use of natural resources made by mining, agriculture, livestock, logging, fishing, nature tourism, and energy production and consumption. This use results in an ecological footprint, i.e., the productive land and sea surface required to generate the consumed resources and absorb the resulting waste, which is about seven times the amount available, a very high number but very similar to other European countries. This overexploitation of natural resources has a huge impact on land and its different forms of cover, air, and water. For the last 25 years, forests and urban areas have each gained almost 3% more of the territory at the expense of agricultural land; those municipalities bordering the sea have increased their number of inhabitants and activity, and although they only occupy 6.7% of the total surface area, they account for 43.3% of the population; air quality has stabilized since the turn of the century, and there has been some improvement in the state of aquatic ecosystems, but still only 36% are in good condition, while the remainder have suffered morphological changes and different forms of nonpoint source pollution; meanwhile the biodiversity of flora and fauna remains still under threat. Environmental policies do not go far enough so there is a need for revision of the legislation related to environmental impact and the protection of natural areas, flora, and fauna. The promotion of environmental research must be accompanied by environmental education to foster a society which is more knowledgeable, has more control and influence over the decisions that deeply affect it. Indeed, nature conservation goes hand in hand with other social and economic challenges that require a more sustainable vision. Today’s problems with nature derive from the current economic model, which is environmentally unsustainable in that it does not take into account environmental impacts. Lastly, we propose a series of reasonable and feasible priority measures and actions related to each use made of the country’s natural resources, to the impacts they have had, and to their management, in the hope that these can contribute to improving the conservation and management of the environment and biodiversity and move towards sustainability.

En esta investigación se analiza la implantación de la docencia semipresencial en el grado universitario de la Universidad de Barcelona. En el estudio se han identificado aquellos grados universitarios en los que la docencia semipresencial tiene, a nivel institucional, un peso específico importante. En ellos se analizan los motivos que han determinado la aplicación de dicha modalidad docente, así como la problemática derivada tanto de su implantación estructural como la referida a su impartición. La metodología utilizada se ha basado en entrevistas y cuestionarios semiestructurados específicos para responsables académicos y profesorado implicado. Se aportan, a modo de valoraciones finales, un conjunto de reflexiones que pueden ser de utilidad en posteriores experiencias, y se enmarcan en las tendencias europeas de futuro en la docencia semipresencial.

La morfologia de les granes de 28 espècies de Delphinium recollides a Turquia ha estat estudiada per mitjà de la Microscòpia Electrònica de Rastreig (MER). Quatre tipus principals de granes són reportats: subgloboses amb anells continus de lamelles, subpiramidals amb esquames amples o primes, subpiramidals allargades amb esquames i sector-esferoïdals reticulades, que es corresponen amb les seccions reconegudes en els sistemes taxonòmics habituals del gènere, cosa que indica llur bona resolució taxonòmica. Es discuteixen les implicacions biogeogràfiques i sistemàtiques.

S'estudia la morfologia de les càpsules i les granes de les espècies d' Euphorbia aggr. flavicoma a l'Europa Occidental. S'ha investigat un total de 1500 granes de 13 tàxons amb microscopi òptic, microscopi electrònic de rastreig i lupa bincular. Les dades han estat sotmeses a una anàlisi multivariant i es presenta el corresponent dendrograma. Al final del treball s'aporta una clau que permet distingir els tàxons a nivell d'espècie per mitjà de caràcters de la càpsula i de la grana.

[ca] Les característiques avançades de Delphinium L. subgèn. Delphinium (tàxons anuals) són comparades amb les del subgèn. Delphinastrum (DC.) Wang i del subgèn. Oligophyllon Dimitrova (tàxons perennes). La morfologia norai mostra un intercanvi de funcions entre els pètals laterals i els pètals superiors i l'estructura de la inflorescència de molts tàxons anuals afavoreix un augment de les taxes de geitonogàmia-autogàmia. L'evolució dels cariotips és basada en una disminució de la longitud total dels cromosomes i en un increment del grau d'asimetria; el nombre cromosòmic roman constant per a totes les espècies anuals (2n = 16). l'eficàcia de la dispersió de les espècies anuals és mes gran que no pas la de les espècies perennes, per causa d'un increment en la producció de granes i per l'augment de la flotabilitat. tant a l'aire com a l'aigua. D'altres característiques adaptatives avançades són l'adquisició de noves defenses químiques i l'aparició d'un nou tipus embriogènic. Els nínxols ecològics del subgèn. Delphiniumcorresponen a hàbitats oberts i alterats, en comparació amb els hàbitats estables i relativament tancats dels subgèneres Delphinastrum i Oligophyllon. Es presenta una hipòtesi global de les tendències evolutives observades en anuals vs. perennes en connexió amb consideracions biogeogràfiques, així com un taxonòmic final.

S'han estudiat els nombres cromosòmics i l'estructura deis cariotipus de 15 poblacions nordafricanes de Delphinium L. sect. Delphinium. Delphinium balansae Boiss. & Reuter, amb cariotipus mes simètric, apareix com a possible ancestre perenne de la resta d’espècies anuals amb cariotipus més asimètric i més curt. Es proposa una reorganització taxonòmica de la secció, d'on es descriu en dues series noves (ser. Macropetala ser. nova i ser. Balansae ser. nova.) i es proposen dues combinacions noves (D. nanum subsp. alboliliaceum and D. nanum subsp. elongatum).

Se aportan nuevos datos sobre la anatomía, ciclo biológico, morfología de la semilla, ecología y nomenclatura de Halopeplis amplexicaulis (Vahl) Cesati & al., único representante del género Halopeplis Ung.-Sternb. (Salicorniaceae en la Península Ibérica. Se describe el polen y se estudia el número cromosómico por primera vez en el género.