Selective homogeneous snythesis of dimethyl ether from methanol

Selected Bronsted acidic ionic liquids were tested as homogeneous catalysts for the dehydration of methanol to dimethyl ether. Ionic liquids incorporating an alkanesulfonic acid as a part of the cation, a complex acidic anion, [A(2)H](-), or both, proved to be good catalysts for this process, providing high conversions and selectivities. Homogeneous catalysis in the liquid state represents a novel approach to dimethyl ether synthesis.

Comparison of Dynamics of Extracellular Accesses to the β(1) and β(2) Adrenoceptors Binding Sites Uncovers the Potential of Kinetic Basis of Antagonist Selectivity.

From the molecular mechanism of antagonist unbinding in the ß(1) and ß(2) adrenoceptors investigated by steered molecular dynamics, we attempt to provide further possibilities of ligand subtype and subspecies selectivity. We have simulated unbinding of ß(1) -selective Esmolol and ß(2) -selective ICI-118551 from both receptors to the extracellular environment and found distinct molecular features of unbinding. By calculating work profiles, we show different preference in antagonist unbinding pathways between the receptors, in particular, perpendicular to the membrane pathway is favourable in the ß(1) adrenoceptor, whereas the lateral pathway involving helices 5, 6 and 7 is preferable in the ß(2) adrenoceptor. The estimated free energy change of unbinding based on the preferable pathway correlates with the experimental ligand selectivity. We then show that the non-conserved K347 (6.58) appears to facilitate in guiding Esmolol to the extracellular surface via hydrogen bonds in the ß(1) adrenoceptor. In contrast, hydrophobic and aromatic interactions dominate in driving ICI-118551 through the easiest pathway in the ß(2) adrenoceptor. We show how our study can stimulate design of selective antagonists and discuss other possible molecular reasons of ligand selectivity, involving sequential binding of agonists and glycosylation of the receptor extracellular surface. © 2012 John Wiley & Sons A/S.

Optical Cooling of Atoms in Microtraps by Time-Delayed Reflection

We present a theoretical analysis of a novel scheme for optical cooling of particles that does not in principle require a closed optical transition. A tightly confined laser beam interacting with a trapped particle experiences a phase shift, which upon reflection from a mirror or resonant microstructure produces a time-delayed optical potential for the particle. This leads to a nonconservative force and friction. A quantum model of the system is presented and analyzed in the semiclassical limit.

The molecular dynamics of Trypanosoma brucei UDP-galactose 4'-epimerase:a drug target for African sleeping sickness

During the past century, several epidemics of human African trypanosomiasis, a deadly disease caused by the protist Trypanosoma brucei, have afflicted sub-Saharan Africa. Over 10 000 new victims are reported each year, with hundreds of thousands more at risk. As current drug treatments are either highly toxic or ineffective, novel trypanocides are urgently needed. The T. brucei galactose synthesis pathway is one potential therapeutic target. Although galactose is essential for T. brucei survival, the parasite lacks the transporters required to intake galactose from the environment. UDP-galactose 4'-epimerase (TbGalE) is responsible for the epimerization of UDP-glucose to UDP-galactose and is therefore of great interest to medicinal chemists. Using molecular dynamics simulations, we investigate the atomistic motions of TbGalE in both the apo and holo states. The sampled conformations and protein dynamics depend not only on the presence of a UDP-sugar ligand, but also on the chirality of the UDP-sugar C4 atom. This dependence provides important insights into TbGalE function and may help guide future computer-aided drug discovery efforts targeting this protein.

A 2300 yr record of sago and rice use from the southern Kelabit Highlands of Sarawak, Malaysian Borneo

Rice and sago are today important staples for many subsistence farmers and nomadic hunter-gatherers living in interior Borneo, but the cultural antiquity of these staples remains poorly understood. This study examines a 2300 yr sedimentary record from a palaeochannel near the village of Pa’Dalih in the southern Kelabit Highlands. Pollen and phytolith evidence indicate significant use of the sago palm Eugeissona near the channel during this period. Oryza phytoliths likely belonging to domesticated rice varieties are also recorded, although rice may have been used to a lesser extent than the sago palms. A rise in cultural activity takes place between c. 1715 and 1600 cal. BP, shown by increased frequency of fires.

A current-driven instability in parallel, relativistic shocks

Recently, Bell ( 2004 Mon. Not. R. Astron. Soc. 353 550) has reanalysed the problem of wave excitation by cosmic rays propagating in the pre-cursor region of a supernova remnant shock front. He pointed out a strong, non-resonant, current-driven instability that had been overlooked in the kinetic treatments by Achterberg ( 1983 Astron. Astrophys. 119 274) and McKenzie and Volk ( 1982 Astron. Astrophys. 116 191), and suggested that it is responsible for substantial amplification of the ambient magnetic field. Magnetic field amplification is also an important issue in the problem of the formation and structure of relativistic shock fronts, particularly in relation to models of gamma-ray bursts. We have therefore generalized the linear analysis to apply to this case, assuming a relativistic background plasma and a monoenergetic, unidirectional incoming proton beam. We find essentially the same non-resonant instability observed by Bell and show that also, under GRB conditions, it grows much faster than the resonant waves. We quantify the extent to which thermal effects in the background plasma limit the maximum growth rate.

The effect of level of straw bale provision on the behaviour and leg health of commercial broiler chickens

This study aimed to assess the effect of the number of straw bales (SBs) provided on the behaviour and leg health of commercial broiler chickens. Houses containing ~23 000 broiler chickens were assigned to one of two treatments: (1) access to 30 SBs per house, ‘30SB’ or (2) access to 45 SB per house, ‘45SB’. This equated to bale densities of 1 bale/44 m2 and 1 bale/29 m2 of floor space within houses, respectively. Treatments were applied in one of two houses on a commercial farm, and were replicated over six production cycles. Both houses had windows and were also artificially lit. Behaviour was observed in weeks 3 to5 of the cycle. This involved observations of general behaviour and activity, gait scores (0: perfect to 5: unable to walk) and latency to lie (measured in seconds from when a bird had been encouraged to stand). Production performance and environmental parameters were also measured. SB density had no significant effect on activity levels (P>0.05) or walking ability (P>0.05). However, the average latency to lie was greater in 30SB birds compared with 45SB birds (P<0.05). The incidence of hock burn and podo dermatitis, average BW at slaughter and levels of mortality and culling were unaffected by SB density (P>0.05). The results from this study suggest that increasing SB levels from 1 bale/44 m2 to 1 bale/29 m2 floor space does not lead to significant improvements in the welfare of commercial broiler chickens in windowed houses.

Impossible Participation

The chapter critiques the rise of participation in art since the 1990s – a development that sees artists and curators searching continually for new and increased levels of audience inclusion. While there has been much discussion about what might be gained by participating in an artwork, we ask what might be lost by this act. We also question the extent to which participation is a useful social or aesthetic strategy in circumstances where it remains bound by the institutional structures of the artworld. For this reason, our work is an attempt to transform the broader ‘apparatus of art’ and to create works in which the roles assigned to individuals and groups remain fluid and subject to continuous negotiation. As a means of an attempt at resisting absorption into the institutional structures of the artworld, we privilege a form of participation that remains immanent in the work, but that never crystallizes into a single or definable role. Kathryn Brown , art historian and editor of Interactive Contemporary Art, says, ‘It is, perhaps, a fitting end to the discussions of the present volume that the most interesting and valuable form of participation envisaged by Freee is one that must remain impossible.’

As lendas de mouras encantadas

Dissertação de mest., Literatura Portuguesa, Faculdade de Ciências Humanas e Sociais, Univ. do Algarve, 2004

Um escritor algarvio do século XVIII em Ayamonte: Damião António de Lemos Faria e Castro

Damião António de Lemos Faria e Castro foi o mais importante escritor algarvio do século XVIII. Viveu entre 1715 e 1789, em Portimão e em Faro, e foi autor de duas obras de grande dimensão: Aula da nobreza lusitana, em sete tomos (entre 1749 e 1761), e História Geral de Portugal e suas Conquistas, em vinte tomos (o primeiro dos quais aparecido em 1786 e os últimos, já póstumos, em 1806). Em ambas recorre amiúde a autores espanhóis, demonstrando a integração e a unidade fundamental da cultura ibérica. Além disso, escrevia correntemente em língua castelhana. Mas Damião esteve também vinculado muito especialmente a Ayamonte. Com efeito, durante cerca de dois anos – 1749/1750 – esteve refugiado em Ayamonte, porque perseguido pela justiça portuguesa. E nesta cidade andaluza da foz do Guadiana compôs alguns opúsculos que mandou imprimir em Sevilha. Outros escritos seus de Ayamonte ficaram manuscritos, como seja a Relación Geográfico-Historica de algunos terrenos de la Frontera de Portugal, y España, desde Ayamonte hasta Badajoz.

Identity, Well-being and Effectiveness: the Emotional Contexts of Teaching

This paper draws on findings from a four‐year longitudinal research project, commissioned by the Department for Education and Skills (DfES), which investigated Variations in Teachers’ Work, Lives and Effectiveness (VITAE). Drawing on data gathered from 300 teachers working in 100 primary and secondary schools in England, the research identified associations between commitment and effectiveness (perceived and in terms of pupil attainment) and found that there were more, and less, effective teachers in each of six professional life phases. It found that teachers in each of these phases experienced a number of different scenarios that challenged their abilities to sustain their commitment (i.e. remain resilient). This paper discusses how these impact, positively and negatively, on teachers’ capacities for sustaining their initial commitment and associations between identity, well‐being and effectiveness. It finds that teacher identities are neither intrinsically stable nor intrinsically fragmented, but that they can be more, or less, stable and more or less fragmented at different times and in different ways according to the influence of the interaction of a number of personal, professional and situated factors. The extent to which teachers are able to and are supported in managing the scenarios they experience will determine their sense of effectiveness.

Late twentieth century congressional leaders as shapers of and hostages to political context: Gingrich, Hastert, and Lott

Most contemporary explanations of congressional leadership postulate a version of contextual theory that typically places greatest emphasis on the strength of party and downplays the personal skills of individual leaders. By analyzing the leadership of just three recent individuals—Gingrich, Hastert, and Lott—this essay demonstrates the extent to which these leaders' different styles, skills, and characteristics interacted with changing political contexts and strategic environments to impact political and policy outcomes. Context matters, but so does leadership skill. Most graphically, Gingrich—a rare transforming leader in Burns' typology—demonstrates the importance of the right person and the right conditions being in place at the same time and the ability of an individual imaginative leader to intervene exogenously to have a significant effect on policy outcomes. Yet the essay also demonstrates that even where leaders adopt more conventional transactional styles, as Hastert and Lott did, the skill and success with which they juggle political pressures emanating from different, often conflicting, contexts—skills in context—also matters.

Re-negotiating Ideologies of Bilingualism on the Margins of Education

This article reports on an ethnographic study carried out in three interrelated sites: two contrasting secondary schools and a Youth-Club (the principal focus of this article), in an area of southwest Wales. This article highlights the incongruence between the language at home and the language of the school and posits that the relationship between language use at school and in the wider community needs to be problematised and questioned far more than has been done thus far. This study questions whether school-based ideologies and school-based practices are re-negotiated or contested on the margins of education and whether this re-negotiation and contestation plays an important role in whether a young person chooses to use Welsh or English outside of school. It will be argued that recreational spaces, even though loosely connected to schools as institutions, function as more open spaces where institutional ideologies are actively reworked and renegotiated, either through choosing to use English or by mixing and blending different aspects of linguistic resources, or by re-negotiating and questioning which version of Welshness is more valuable, ‘the removed and authentic’ (as seen at the Welsh school) or the ‘new and hybrid’ as seen at the Youth-Club.