1,394 research outputs found
[Cathedral in Santiago de Compostella]
No full textPhotograph of a cathedral in Santiago de Compostella from the street. The grey, stone brick cathedral is visible through stone buildings on either side. Arches sit along the top layers of the tower is surrounded by small offshoots with dome roofs. A white clock sits along the tower at its center. Rectangular, white windows sits along the left building above arches. A flag hangs off a building to the right at the bottom of the photograph
Mapping precedence into containment: linear ordering in a bidimensional space
No full textThere is an almost unanimous theoretical consensus according to which human languages are externalized as linear sequences of atomic units which are encoded according to specific hierarchical conditions. The nature of the interplay between the cognitive development of these hierarchical representations and their linearization on the string is however still not clear. In this paper, we aim to address this issue, exploring the relationship between precedence and containment by capitalizing on the results of a new experimental paradigm that has already provided interesting insights (Vender et al. 2019, 2020). More specifically, we report the results of two modified Simon Tasks in which the sequence of stimuli is determined by the rules of the Fibonacci grammar (Fib) or of its modifications Skip and Bif. All three grammars share the same transitional regularities, but they crucially differ in their structure: only Fib is characterized by the presence of so-called k-points, which provide, from a purely computational perspective, a potential bridge to full hierarchical reconstruction. We tested 64 adults’ implicit learning skills, assessing learning of the statistical regularities in Fib, Skip and Bif, while also exploring the presence of hierarchical learning, in terms of the ability to predict k-points. Results provide evidence not only for the presence of statistically-based sequential learning, but also for hierarchical learning in Fib. We argue that the relations of precedence and containment are not antagonistic ways of processing a temporally ordered sequence of symbols; rather, they are strictly interdependent implementations of an abstract mathematical relation of linear ordering within a bidimensional computational space. We propose that the construction of this bidimensional space is primarily determined by labeling requirements, with the labeling algorithm emerging as the solution to the problem of mapping precedence into containment
Synthesis of photoactivable probes for the study of glycosphingolipid-protein interactions
No full textSYNTHESIS OF PHOTOACTIVABLE PROBES FOR THE STUDY OF GLYCOSPHINGOLIPID-PROTEIN INTERACTIONS
Giuseppina Brasile,1 Federica Compostella,1 Laura Mauri,2Sandro Sonnino2 and Fiamma Ronchetti1
Dipartimento di Chimica, Biochimica e Biotecnologie per la Medicina, Università di Milano
1Via Saldini 50, 20133-Milano, Italy; 2Via Fratelli Cervi 93, 20190- Segrate (Milano), Italy
E-mail:[email protected]
It is widely accepted that glycosphingolipids (GSLs) at the level of the plasma membrane can affect the biological functions of protein molecules, such as cell surface receptors or transporters. The interactions between GSLs and proteins belonging to specific membrane microdomains, called lipid rafts, could be responsible for the modulation of the functional properties of membrane proteins participating in signal transduction. GSL-protein interactions can be investigated by cell photolabelling experiments using radioactive photoactivable GSLs, which yield, when illuminated, a very reactive intermediate that covalently binds to the molecules in the environment, i.e. proteins.1,2
In this context, we have designed a fatty acid probe with two nitrophenylazide photoactivable groups, one at position 2 and the other at the end of the acyl chain. The conjugation of the fatty acid to a radioactive sphingoglycolipid generates a species to be used for photolabelling experiments. In this way, the simultaneous identification of the proteins belonging to both the leaflets of the plasma membrane, the cytoplasmatic and the extracellular one, will be realized.
Herein we describe a general synthetic strategy to obtain not commercially available α,ω-diamino acids, the synthetic precursors of the labelled fatty acids, which we have applied to the synthesis of a C-18 derivative. Furthermore, it will be described the preparation of a photolabelled radioactive GSL as a case study.
1. Aureli M., Prioni S., Mauri L. Loberto N., Casellato R., Ciampa M.G., Chigorno V., Prinetti, A.; Sonnino S. J. Lipid Res. 2010, 51, 798-808
2. Mauri L., Prioni S., Loberto N., Chigorno V., Prinetti A., Sonnino S. Glycoconj. J. 2004, 20, 11-23
Language and perception. Investigating linear and hierarchical implicit statistical learning across the visual, auditory, and tactile sensory domains.
No full textThis thesis explored how humans process and form recursive hierarchical structures arising from temporally ordered sequences of stimuli, across the visual, auditory, and tactile sensory domains. As we will explain throughout this thesis, we posit that the ability to form recursive hierarchical abstract representations from temporally ordered stimuli is a cognitive ability involved in human syntax processing and acquisition. Language unfolds in a linear fashion. Words follow one another, creating sentences that, on the surface, appear as linear sequences of sounds or symbols. However, a purely sequential arrangement of words alone falls short in encompassing the complexities of human language syntax. It is evident that the syntax of human languages has a fundamental hierarchical dimension, where constituents are organized in a way that is intricately linked to their linear order. Among the various syntactic phenomena that depend on this hierarchical organization, recursion is one of the most fascinating and controversial in the study of language. Recursion in human syntax, understood as the characteristic of embedding constituents within constituents of the same kind, has long been considered a fundamental and distinctive feature of human language. Therefore, the cognitive ability to deal with recursion has been viewed as crucial for language capacity, possibly representing a uniquely human faculty at the core of language ability. However, this topic is highly controversial. Despite the importance attributed to recursion in linguistics, several questions remain open. What is the role of recursion in human language? Is the ability to handle recursion specifically tied to the human language faculty? What is the mechanism underlying the cognitive ability to form recursive abstract representations in language, considering both the linear and hierarchical nature of syntax? To analyze this topic, this thesis will delve into three critical issues at the core of theoretical and experimental linguistic debates. The first issue addresses the debated role of recursion in human language syntax. The second issue examines the contributions of recursive hierarchical abstract representation and statistical learning to the acquisition and processing of human syntax. The third issue, intimately connected to the second, examines the existence of domain-specific representational and learning constraints, alongside the influence of domain-general learning abilities on this process. Our research had two main objectives: Firstly, we aimed to determine whether sequential statistical learning and the formation of recursive hierarchical abstract representation operate independently as distinct levels of language analysis or if they work together synergistically as complementary learning mechanisms. If they complement each other, we sought to understand the cognitive processes involved in transitioning from linear to recursive hierarchical dimensions. Secondly, we investigated whether the ability to form recursive hierarchical abstract structures from sequential stimuli is a language-specific ability or a domain-general ability, shared across different modalities and whether there are domain-specific differences in this ability between sensory domains. To address these inquiries, we employed the Artificial Grammar Learning paradigm, conducting three Serial Reaction Time tasks. Three distinct groups of adult participants were presented with a sequence of stimuli featuring the rules of a non-canonical binary grammar belonging to the Lindenmayer systems: The Fibonacci grammar (Fib). The choice to use this grammar was driven by its exceptional suitability for thoroughly investigating this research topic in all its various facets. On one hand, it allows for the investigation of the application of recursive algorithms for predicting points in the string, while simultaneously examining the relationship between sequential statistical learning and the creation of recursive hierarchical representations. On the other hand, this paradigm permits the examination and direct comparison of these cognitive abilities across different sensory modalities. In the three tasks, the symbols of Fib were encoded onto auditory tones, vibrotactile impulses, or colorful visual shapes. Through analysis of reaction times and accuracy data in response to perceived stimuli, we explored whether participants implicitly learned the regularities of Fib across all three sensory domains and potentially domain-specific learning differences. Our findings suggested a close linkage between the ability to form recursive hierarchical representations and the capacity to grasp low-level transitional regularities. With this regard, we introduced a cognitive parsing algorithm hypothesizing the cognitive mechanisms involved in transitioning from sequence to hierarchy. Furthermore, we observed that the cognitive ability to process and learn these structures, which underpin human language, is a domain-general ability present across diverse sensory domains. However, we also identified domain-specific differences, with auditory and tactile modalities exhibiting a distinct advantage over the visual domain. In summary, our results indicated that sequential statistical learning and recursive hierarchical abstract representation synergize as complementary modes of learning, rather than operating as distinct levels of language analysis. Moreover, our findings suggest that the capability to from recursive hierarchical abstract structures arising from temporally ordered stimuli is not a language-specific ability but rather a domain-general capacity present across different sensory modalities, potentially interacting with language in specific ways
A comparison between different treeline types shows contrasting responses to climate fluctuations
No full textTreeline position is mainly determined by growth season temperature, but the response of treelines to climate warming is not uniform worldwide. We compared treeline structure, dynamics and thermal profile in nearby areas with different treeline type, species composition and bioclimatic conditions. We performed a detailed survey of different treeline types in three areas of Italian Alps and northern Apennines. Every tree individual was recorded along altitudinal transects from the closed forest to the species limit. Treeline structure and dynamics were described through altitudinal limits of tree height, density and age. Data were elaborated by principal components analysis. Temperature regime of the three sites was assessed from homogeneous historical climatic data. Treeline was different in the three areas for species composition, shape and dynamics. Both Alpine sites showed diffuse treeline, but only one showed advancing dynamics. Apennine treeline was abrupt and static, with higher temperature at the tree limit. Our study showed the variable dynamics of treelines within a relatively restricted area and the connection between treeline shape and dynamics. An important role is played by species composition, determined by bioclimatic and historical features. These factors should be taken into account when modelling future treeline dynamics at global scale
Analisi di nuove strategie terapeutiche per pazienti in età pediatrica affetti da tumori solidi refrattari alla chemioterapia standard
No full textThe PhD research work was performed at the Pediatric Hemato-Oncology Department of Padua University, one of the major AIEOP (Associazione Italiana di Emato-Oncologia Pediatrica) Centres and the coordinating centre of the Soft Tissue Sarcoma Committee (STSC) protocol EpSSG 2005 for pediatric soft tissue sarcomas. The primary goal of the PhD was analyzing new therapeutic strategies for resistant solid tumors children. The work moved from data analysis on adolescents with rhabdomyosarcoma (RMS) and resistant RMS patients treated with a new second line topotecan (T)/carboplatin (C) based regimen, through a specific training in clinical trials management to obtain the necessary expertise to write down a phase II trial for resistant RMS patients. In the last decades in many types of cancer the survival rates are reported to be less favorable in adolescents compared with younger children. To investigate whether this is true for adolescents with RMS, the results obtained in patients enrolled in protocols run by the Italian STSC were analyzed. Our study concluded that the higher prevalence of unfavorable tumor characteristics among adolescents seems to explain their worse outcome, the limited number of adolescents enrolled in STSC studied is worrisome and cooperation with adult oncologists needs to be improved. Another bad result is about prognosis of children with metastatic or resistant RMS: there is a strong need to find new strategies to improve the outcome of these patients. T and C are known to have activity against a variety of pediatric tumors so a T/C based chemotherapy has been proposed as second line CT for children relapsed after being treated in the STSC protocols. Our study shows that the T/C combination is tolerable in heavily pretreated patients; the response rate (RR) is somewhat lower when compared to other combinations tested in phase II studies but it’s of interest for the population with alveolar subtype. Clinical trials are one of the most important tools to explore new therapeutic approaches; for this reason the PhD involved a specific training in clinical trials management through participation to courses ad hoc, creation of a team committed to new drugs environment, participation to international phase II and III trials. During the last part of PhD the efforts were coordinated to write a phase II trial on treatment of leptomeningeal dissemination by RMS. Neoplastic meningitis is a devasting complication of both solid and hematologic tumors and despite treatment the median survival duration is in the range of 8-16 weeks. Among available therapeutic approaches intrathecal (IT) chemotherapy is one of the most widely used even if no impact on survival has been demonstrated. Few anticancer agents are used in this setting, therefore it’s essential to develop new IT agents with novel mechanism of action. Topotecan showed interesting results, then we designed a phase II study with IT topotecan in patients with RMS and EPNET tumors and leptomeningeal spread
La degradacion del salario real de los trabajadores urbanos en Santiago de Compostella a finales del Antiguo Regimen
No full textEiras Roel A. La degradacion del salario real de los trabajadores urbanos en Santiago de Compostella a finales del Antiguo Regimen. In: Cahiers de la Méditerranée : série spéciale, n°3, 1, 1975. La force de travail dans les cités méditerranéennes du milieu du XVIIIe au milieu du XIXe siècle. Actes des journées d'études Bendor, 19 et 20 avril 1974. pp. 17-56
Reduction of aromatic steroidal A rings by lithium in ethyl amine
No full textThe reduction of 3-methoxy-estra-1,3,5(10)-trien-17β-ol (6) and 13-ethyl-3-ethoxy-gona-1,3,5(10)-triene-11α,17β-diol (2) by lithium in ethyl amine in the absence of a proton source is described. Both reductions, contrary to the reports of previous investigators, which indicated the 4-ene to be the main reaction product, gave a complex mixture of products. In the case of the reduction of 2, which is an intermediate in the synthesis of the progestagen desogestrel (1), we obtained the expected known 13-ethyl-gona-4-ene-11α,17β-diol (4) in small amounts and three new steroidal monoenes, 13-ethyl-gona-5(10)-ene-11α,17β-diol (11), 13-ethyl-gona-5(6)-ene-11α,17β-diol (12), and 13-ethyl-gona-1(10)-ene-11α,17β-diol (13). These compounds were characterized as the 11,17-diacetates with the 5(10)-ene 11 being the major compound
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