917 resultados para Recent past


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This overview presents the recent progress in the area of endohedral metallofullerenes in the past several years. The important results have been summarized as follows: (1) Many metals including Group 3 metals, most of the lanthanide series elements, and Group 2 metals have been encapsulated into a fullerene cage to form mono-, di-, and trimetallofullerenes by using the arc-evaporation technique. (2) Some endohedral metallofullerenes such as Group 3 metals, most of the lanthanide series elements, Group 2 metals, and some of their isomers have been successfully isolated and purified by a two-step or several-step HPLC technique. By using high-temperature and high-pressure extraction with pyridine, Ln@C-80, Ln@C-82, and Ln2@C-80 for most rare-earth metals have been selectively extracted in high yield (about 1% of the saw soot) from fullerenes and other size metallofullerenes. (3) The endohedral nature of metallofullerenes such as Y@C-82, Sc2@C-84, and Sc@C-82 has been finally confirmed by synchrotron X-ray powder diffraction. The symmetries and the structures of metallofullerenes such as Ca@C-82(III), La-2@C-80(I-h), Sc-2@C-84(D-2d), and Sc-2@C-84(C-s) have been confirmed by NMR measurements. (Lb) The information on the electronic structures and properties of endohedral metallofullerenes has been obtained by various spectrometric means Such as EPR, W-vis-MR, XPS, CV. It is generally accepted that three-electron transfer is favorable when M = Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Lu but Sc, Eu, Sm, Yb, Tm, Ca, Sr, Ba prefer to donate two electrons to the fullerene cages. (5) Several chemical reactions of endohedral metallofullerenes have been reported in which reagents are disilacyclopropane, digermacyclopropane, diphenyldiazomethane, and trifluoroacetic acid. (6) Mass spectrometry provided the crucial evidence that led to the discovery of metallofullerenes in 1985 and has always played a key role in their identification and characterization, Ion-mobility measurements of gas-phase ions have obtained the information of structures and the formation mechanism of endohedral metallofullerenes. till Theoretical calculations on the endohedral metallofullerenes have made an important contribution to the studies on the symmetry of the cage, the position of metal atom(s) inside the cage, the number of electronic transfer between metal atom(s) and fullerene cage, etc. (C) 2000 Elsevier Science S.A. All rights reserved.

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Algae have been part of Chinese life for thousands of years. They are widely used as food and have been cited in Chinese literature as early as 2500 years ago. However, formal taxonomic studies on Chinese algae were initiated by foreign scientists only about 200 years ago, and by Chinese phycologists only about 90 years ago. This paper summarizes the history of modern phycological studies on Chinese algae and provides an overview of the achievements of phycological studies by Chinese scientists, especially on algal taxonomy, morphology, genetics, ecology and environmental research, physiology, biotechnology, algal culture, applied phycology and space phycology, in the last century. Recent development in phycological research focuses on algal floristic and molecular systematics, algal molecular biotechnology, applied phycology including micro and macroalgal cultivation and algal product development, and the roles of algae in environmental pollution control. These areas will also be the main focuses of Chinese phycological research in the foreseeable future.

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Sediment geochemical technique was employed to assess how the sediment records reflect the environmental changes of Jiaozhou Bay, a semi-enclosed bay adjacent to Qingdao, China. In the past hundred years, Jiaozhou Bay has been greatly impacted by human interventions. A dated core sediment by Pb-210 chronology was analyzed for trace metals including Li, Cd, Cr, Pb, Cu, Ni, Co, Zn together with C, N, P and BSi. Based on the research, the development of Jiaozhou Bay environment in the past hundred years can be divided into three stages: (1) before the 1980s characterized by relatively low sedimentation rate, weak heavy metal pollution and scarce eutrophication; (2) from the 1980s to 2000, accelerating in the 1990s, during which high sedimentation rates, polluted by heavy metals and the frequent occurrence of red tide; (3) after 2000, the period of the improvement of environment, the whole system has been meliorated including the heavy metal pollution and hypernutrification. (c) 2006 Elsevier Ltd. All rights reserved.

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Phosphorus is a key element and plays an important role in global biogeochemical cycles. The evolution of sedimentary environment is also influenced by phosphorus concentrations and fractions as well as phosphate sorption characteristics of the marine sediments. The geochemical characteristics of phosphorus and their environmental records were presented in Jiaozhou Bay sediments. Profiles of different forms of phosphorus were measured as well as the roles and vertical distributions of phosphorus forms in response to sedimentary environment changes were investigated. The results showed that inorganic phosphorus ( IP) was the major fraction of total phosphorus ( TP); phosphorus which is bound to calcium, iron and occluded phosphorus, as well as the exchangeable phosphorus were the main forms of IP, especially calcium-phosphorus, including detrital carbonate-bound phosphorus ( Det - P) and authigenic apatite-bound phosphorus ( ACa - P), are the uppermost constituent of IP in Jiaozhou Bay sediments. Moreover, the lead-210 chronology technology was employed to estimate how much phosphorus was buried ultimately in sediments. And the research showed that the impacts of human activities have increased remarkably in recent years especially between the 1980s and 2000. According to research, the development of Jiaozhou Bay environment in the past hundred years can be divided into three stages; (I) before the 1980s characterized by the relatively low sedimentation rate, weak land-derived phosphorus inputs and low anthropogenic impacts; (2) from the 1980s to around 2000, accelerating in the 1990s, during which high sedimentation rates, high phosphorus abundance and burial fluxes due to the severe: human activities impacted on the whole environmental system; (3) after 2000, the period of the improvement of environment, the whole system has been improved including the decreasing sedimentation rates, concentration and the burial fluxes of phosphonas.

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Background and Aims Rheum, a highly diversified genus with about 60 species, is mainly confined to the mountainous and desert regions of the Qinghai-Tibetan plateau and adjacent areas. This genus represents a good example of the extensive diversification of the temperate genera in the Qinghai-Tibetan plateau, in which the forces to drive diversification remain unknown. To date, the infrageneric classification of Rheum has been mainly based on morphological characters. However, it may have been subject to convergent evolution under habitat pressure, and the systematic position of some sections are unclear, especially Sect. Globulosa, which has globular inflorescences, and Sect. Nobilia, which has semi-translucent bracts. Recent palynological research has found substantial contradictions between exine patterns and the current classification of Rheum. Two specific objectives of this research were (1) to evaluate possible relationships of some ambiguous sections with a unique morphology, and (2) to examine possible occurrence of the radiative speciation with low genetic divergence across the total genus and the correlation between the extensive diversification time of Rheum and past geographical events, especially the recent large-scale uplifts of the Qinghai-Tibetan Plateau.Methods The chloroplast DNA trnL-F region of 29 individuals representing 26 species of Rheum, belonging to seven out of eight sections, was sequenced and compared. The phylogenetic relationships were further constructed based on the sequences obtained.Key Results Despite the highly diversified morphology, the genetic variation in this DNA fragment is relatively low. The molecular phylogeny is highly inconsistent with gross morphology, pollen exine patterns and traditional classifications, except for identifying all samples of Sect. Palmata, three species of Sect. Spiciformia and a few species of Sect. Rheum as corresponding monophyletic groups. The monotypic Sect. Globulosa showed a tentative position within the clade comprising five species of Sect. Rheum. All of the analyses revealed the paraphyly of R. nobile and R. alexandrae, the only two species of Sect. Nobilia circumscribed by the possession of large bracts. The crude calibration of lineages based on trnL-F sequence differentiation implied an extensive diversification of Rheum within approx. 7 million years.Conclusions Based on these results, it is suggested that the rich geological and ecological diversity caused by the recent large-scale uplifts of the Qinghai-Tibetan Plateau since the late Tertiary, coupled with the oscillating climate of the Quaternary stage, might have promoted rapid speciation in small and isolated populations, as well as allowing the fixation of unique or rare morphological characters in Rheum. Such a rapid radiation, combined with introgressive hybridization and reticulate evolution, may have caused the transfer of cpDNA haplotypes between morphologically dissimilar species, and might account for the inconsistency between morphological classification and molecular phylogeny reported here.

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Sadler, J. Grattan, J. Volcanoes as agents of past environmental change. Global and Planetary Change. 1999. 21 pp 181-196

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The centromere is the chromosomal locus essential for chromosome inheritance and genome stability. Human centromeres are located at repetitive alpha satellite DNA arrays that compose approximately 5% of the genome. Contiguous alpha satellite DNA sequence is absent from the assembled reference genome, limiting current understanding of centromere organization and function. Here, we review the progress in centromere genomics spanning the discovery of the sequence to its molecular characterization and the work done during the Human Genome Project era to elucidate alpha satellite structure and sequence variation. We discuss exciting recent advances in alpha satellite sequence assembly that have provided important insight into the abundance and complex organization of this sequence on human chromosomes. In light of these new findings, we offer perspectives for future studies of human centromere assembly and function.

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During the last decade Quaternary pollen analysis has developed towards improved pollen-taxonomical precision, automated pollen identification and more rigorous definition of pollen assemblage zones. There have been significant efforts to model the spatial representation of pollen records in lake sediments which is important for more precise interpretation of the pollen records in terms of past vegetation patterns. We review the difficulties in matching modelled post-glacial plant migration patterns with pollen-based palaeorecords and discuss the potential of DNA analysis of pollen to investigate the ancestry and past migration pathways of the plants. In population ecology there has been an acceleration of the widely advocated conceptual advance of pollen-analytical research from vaguely defined ‘environmental reconstructions’ towards investigating more precisely defined ecological problems aligned with the current ecological theories. Examples of such research have included an increasing number of investigations about the ecological impacts of past disturbances, often integrating pollen records with other palaeoecological data. Such an approach has also been applied to incorporate a time perspective to the questions of ecosystem restoration, nature conservation and forest management. New lines of research are the use of pollen analysis to study long-term patterns of vegetation diversity, such as the role of glacial-age vegetation fragmentation as a cause of Amazonian rain forest diversity, and to investigate links between pollen richness and past plant diversity. Palaeoclimatological use of pollen records has become more quantitative and has included more precise and rigorous testing of pollen-climate calibration models with modern climate data. These tests show the approximate nature of the models and warn against a too straightforward climatic interpretation of the small-scale variation in reconstructions. Pollenbased climate reconstructions over the Late Glacial–early Holocene boundary have indicated that pollen-stratigraphical changes have been rapid with no evidence for response lags. This does not rule out the possibility of migrational disequilibrium, however, as the rapid changes may be mostly due to nonmigrational responses of existing vegetation. It is therefore difficult to assess whether the amplitude of reconstructed climate change reflects real climate change. Other outstanding problems remain the obscure relationship of pollen production and climate, the role of human impact and other nonclimatic factors, and nonanalogue situations.

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This article discusses the so-called newness of today's antisemitism through the historical and social specificities of antisemitism in French society. It casts light on the continuities of antisemitic discourse in France, but also its transformation in relation to the French colonial heritage and the recent ‘communitarianisation’ of France's social life. This analysis of antisemitism is furthered by the presentation of two case-studies: the controversial discourses of comedian Dieudonné and Kémi Séba, leader of a black supremacist movement called Tribu KA which stirred controversies in the 2000s. These two examples emphasise the fact that antisemitic discourse is better understood as a narrative about downward social mobility and status, which hardly makes antisemitism new.

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The complex of buildings at Struell Wells, near Downpatrick, Co. Down, is the most extensive at a holy well in Ireland. It comprises two wells, two bath-houses and the ruins of a church. Nearby is a natural rock feature known as St Patrick’s Chair. The earliest reference to the wells is likely to be in the 8th century Fíacc’s Hymn which records the site being visited by St Patrick. The earliest reference to their healing powers can be dated to the 11th/12th century and the site continued to be a focus of pilgrimage at midsummer until its suppression in the nineteenth century. The site seems to be unique in that bathing in the wells constituted an integral part of the rituals performed by pilgrims. A recent study of the holy well phenomenon in Ireland has suggested that the rituals associated with them have their origins in the Counter-Reformation (Carroll 1999). The evidence from Struell, however, strongly suggests that it was an important sacred site in pre-Christian times.

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The question of whether Northern Ireland should have a formal truth recovery process has been amplified by the recent Report of the Consultative Group on the Past. Compared to the volume at which the truth recovery debate has been played out, relatively little is known about policing attitudes to this form of dealing with the past. This paper analyses the ways in which the history and context of policing in Northern Ireland have shaped attitudes towards truth recovery. It will be argued that differing opinions on the need for truth recovery are part of a debate over 'ownership of the past' between the ardent supporters of the Royal Ulster Constabulary and the new post-Patten managers and modernizers.

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This article introduces examples of recent sound art in Belfast, a city that has undergone radical transformation over the past decade and is home to a burgeoning community of sound artists. The text investigates the ways in which sonic art can redraw boundaries in a city historically marked by myriad political, socioeconomic,
religious and sectarian divisions. The article focuses on sound works that reimagine a “post-conflict” Belfast. These include site-specific sound installations in urban and public spaces, soundwalks, sculptures, locative and online works, and experimental
sonic performances that draw upon traditional Irish song and music.

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Contested understandings about the past continue to reify the divided character of post-Troubles Northern Ireland. In particular, the unresolved legacies of the extension of English control over Ireland in the late sixteenth and early seventeenth centuries through warfare and plantation continue to structure daily lives in the province. Yet the archaeological record of this period complicates the accepted dichotomous narratives through highlighting complexity. These nuances, however, have been lost in recent decades as an overly simplistic model of colonizer versus colonized has emerged as the dominant political paradigm. The management and presentation of sites associated with the process of plantation can arguably create the space necessary to bridge the divide, and to challenge accepted understandings. Cross-community engagement in the process of archaeological discovery and interpretation on plantation-period sites in Northern Ireland highlights the critical role archaeology can play in peace and reconciliation in post-conflict societies.

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This paper reviews decisions from the Northern Ireland and England and Wales High Courts and Courts of Appeal as well as the UK Supreme Court relating to tort and principally to the tort of negligence in the past 12 months or so.

In structure, the paper will be presented in four parts. First, three preliminary points relating to contemporary features of the NI civil courts: personal litigants – Devine v McAteer [2012] NICA 30 (7 September 2012); pre-action protocols – Monaghan v Graham [2013] NIQB 53 (3 May 2013); and the rise of alternative dispute resolution. On the last named issue, the recent decision of PGF II SA v OMFS Company 1 Ltd [2013] EWCA Civ 1288 (23 October 2013) on unreasonable refusal to mediate, will be discussed.

Second, the paper moves to consider the law of negligence generally and case law from the NI High Court reiterating Lord Hoffmann’s view in Tomlinson v Congleton Borough Council [2004] 1 AC 46 that no duty of care arises from obvious risks of injury. In this, reference will be made to the application of the above “Hoffmann principle” in West Sussex County Council v Pierce [2013] EWCA Civ 1230 (16 October 2013), which concerned an accident sustained by a child at school. A similar set of facts was presented recently to the UK Supreme Court in Woodland v Essex County Council [2013] UKSC 66 (23 October 2013). The decision there, on non-delegable duties of care, will have a significant impact for schools in the provision of extracurricular activities.

Third, I will review a NI case of note on the duty of care of solicitors in the context of professional negligence in the context of conflicting advice by counsel.

Fourth, I will examine a series of cases on employer liability and including issues such as the duty of care towards the volunteer worker; tort and safety at work principles generally; and, more specifically, the duty of care of the employer towards an employee who suffers psychiatric illness as a result of stress and/or harassment at work. On the issue of workplace stress, the NI courts have made extensive reference to the Hale LJ principles found in the Court of Appeal decision of Hatton v Sutherland [2002] 1 All ER 1 and applied to those who have suffered trauma in reporting on or policing “the troubles” in Northern Ireland. On the issue of statutory harassment at work, the paper will also mention the UK Supreme Court’s decision in Hayes v Willoughby [2013] UKSC 17 (20 March 2013).

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In preparation for this talk I have reviewed cases of interest in the High Courts and Courts of Appeal of England and Wales and Northern Ireland from the past two years or so on professional negligence and liability and principally relating to solicitors.

There are six topics of interest: the general duty of care demanded of solicitors in the carrying out of their professional obligations; whether there is a specific duty on a solicitor to warn or advise a client of any implied risk in, say, a commercial transaction; what is the scope of the duty on a solicitor to explain the content of or clauses in a legal document; a recent case of interest applying the White v Jones principle to a disappointed beneficiary seeking to make a claim against a solicitor who negligently prepared a will; the practical, limitation issue of how to pinpoint in a professional negligence claim when the damage was first sustained by the claimant; and finally some case law here and in England and Wales on the (costs) implications for solicitors relating to any failure to adhere to case management protocols or related court directions.