8,913 research outputs found

    New family of potentials with analytical twiston-like solutions

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    In this letter we present a new approach to find analytical twiston models. The effective two-field model was constructed by a non-trivial combination of two one field systems. In such an approach we successfully build analytical models which are satisfied by a combination of two defect-like solutions, where one is responsible to twist the molecular chain by 180 0180^{\,0}, while the other implies in a longitudinal movement. Such a longitudinal movement can be fitted to have the size of the distance between adjacent molecular groups. The procedure works nicely and can be used to describe the dynamics of several other molecular chains.Comment: 7 pages, 3 figure

    ‘Do U txt?’ – Using ‘txting’ to learn maternal languages: a Portuguese case study

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    Analysing the influence of new technologies/media (e.g., mobile phones, chats, instant messaging services) on the use and learning of maternal languages basic rules is the goal of this investigation, involving teachers and students (10th, 11th and 12th grade pupils, aged between 16 and 21) at the Escola Secundária de Silves – ESS (Algarve/Portugal), and extended to include at the Irish School of St. Tiernan’s Community (Dublin/Ireland). The use of txting, commonly pointed out as being responsible for the destruction of correct knowledge/mastery of maternal language rules in younger people is, however, in our opinion, one more factor proving the constant adaptability/transformation of languages, revealing the user’s high creativity, ability to synthesise and to introduce – in txting itself – different language skill levels. Exercises using txting were developed/applied at the ESS, proving to be motivational (both for students and teachers) and efficient in transmitting Portuguese language rules

    Flora das Culturas Agrícolas da Ilha de Santiago (cabo Verde)

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    Com o objectivo de caracterizar as comunidades vegetais que acompanham as culturas agrícolas de sequeiro e de regadio praticadas em Santiago e, particularmente, no vale da ribeira Seca, efectuaram-se 16 levantamentos titoecológicos ao longo deste curso de água e encostas sobranceiras. A inventaria@0 floristica revelou a presenta de 118 taro pertencenteas 3 3 familias. Analisaram-sea, inda,6 2 levantamentorse alizadose m diversosp ontosd a ilha, tendo sido identificados1 72t axa pertencenteas 42 familiasG. ramineae. Leguminosae e Compositue sao as famílias melhor representadasA. flora inventariadaC comparadac om a referida em trabalhos precedentesr,e alizadosp or outrosa utores,r evelandolao correnciad e, pelo menos,1 82t axa na flora infestante. Os levantamentos da ribeira Seca foram analisadosa travt5sd o programad e análise numérica TWINSPAN, que indicou a presentad e 4 agrupamentosv egetais distintos, cuja interpretacao,a tendendoà s característicase dáticas,c limáticase topográticasd os locais onde ocorrem,s ugeriua disponibilidadeh idrica comoo factorm aisd eterminantde as uac omposicáo. Palavras-chavefl:o ra, adventiciasd asc ulturasT, WINSPAN, ilhasd eC aboV erde, Santiago. In order to identify and to characterizeth e plant communitiesp resenat t the irrigated and dry cropso f ribeira Secav alley, it were established16 s amplep lots. The tloristic inventory has revealedt he presenteo f 118 tara belongingt o 33 families.I n addition,m ore 62 samplep lots,were establishedth roughoutt he island,w hich permittedt he identifkation of 172t ara from 42 families.G ramineae, CompQsitae &ndL eguminosae weret he mostr epresentativeosn es.T his flora is comparedw ith that referred in precedingw orksf rom othersa uthors,r evealingt he occurrence of, at least, 182 tma in the weed flora. The application of the TWINSPAN numerical analysis, to the plots in the ribeira Seca vallcy. has revealed the presente of 4 distinct plant communities, which were related with edaphic,c limatic and topographicf actors.T his analysiss uggestetdh at the water availability wa.s the mainf actor affecting the speciesc ompositionof the communities. Key-words:f lora weedsT, WINSPAN, CapeV erdei slandsS, antiago

    Evolution of Drug Resistance: Insight on TEM β-Lactamases Structure and Activity and β-Lactam Antibiotics

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    Since the discovery of the first penicillin bacterial resistance to β-lactam antibiotics has spread and evolved promoting new resistances to pathogens. The most common mechanism of resistance is the production of β-lactamases that have spread thorough nature and evolve to complex phenotypes like CMT type enzymes. New antibiotics have been introduced in clinical practice, and therefore it becomes necessary a concise summary about their molecular targets, specific use and other properties. β-lactamases are still a major medical concern and they have been extensively studied and described in the scientific literature. Several authors agree that Glu166 should be the general base and Ser70 should perform the nucleophilic attack to the carbon of the carbonyl group of the β-lactam ring. Nevertheless there still is controversy on their catalytic mechanism. TEMs evolve at incredible pace presenting more complex phenotypes due to their tolerance to mutations. These mutations lead to an increasing need of novel, stronger and more specific and stable antibiotics. The present review summarizes key structural, molecular and functional aspects of ESBL, IRT and CMT TEM β-lactamases properties and up to date diagrams of the TEM variants with defined phenotype. The activity and structural characteristics of several available TEMs in the NCBI-PDB are presented, as well as the relation of the various mutated residues and their specific properties and some previously proposed catalytic mechanisms

    Síndrome de Erasmus: uma Entidade Pouco Reconhecida

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    We present a case of a 33-year-old male who worked as a plumber and a locksmith. The patient presented with diffuse myalgia and asthenia, skin sclerosis and puffy fingers, Raynaud's phenomenon, exertional dyspnea and erectile dysfunction. The presence of specific autoantibodies enabled the diagnosis of systemic sclerosis. Chest-computed tomography revealed upper lobe consolidation. After extensive evaluation, the multidisciplinary interstitial lung disease team concluded that the patient also had advanced silicosis. After a year, there was significant clinical, radiologic, and functional deterioration of the lung disease. The patient was referred for lung transplant. Silica inhalation is the cause of silicosis but is also implicated in the development of systemic sclerosis (Erasmus syndrome). Although they share a common risk factor, it is rare to find both diseases co-existing. We present this case of a young patient where both diseases presented aggressively in order to raise awareness to this association.Apresentamos o caso de um homem de 33 anos que trabalhava como canalizador e serralheiro. Apresentava mialgias e astenia, esclerose cutânea e puffy fingers, fenómeno de Raynaud, dispneia de esforço e disfunção erétil. A presença de autoanticorpos específicos permitiu o diagnóstico de esclerose sistémica. A tomografia computadorizada de tórax revelou consolidações dos lobos superiores. Após extensa avaliação, o grupo multidisciplinar de doenças do interstício concluiu que o doente tinha também silicose avançada. Após um ano, houve agravamento clínico, radiológico e funcional significativo da doença pulmonar. O doente foi encaminhado para transplante pulmonar. A inalação de sílica é a causa da silicose, mas também está implicada no desenvolvimento da esclerose sistémica (síndrome de Erasmus). Embora tenham um fator de risco comum, é raro encontrar as duas doenças simultaneamente. Apresentamos o caso de um doente jovem em que ambas as doenças se apresentaram de forma agressiva para alertar sobre esta associação.info:eu-repo/semantics/publishedVersio
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