2,277 research outputs found
Changing patterns of dengue epidemiology and implications for clinical management and vaccines.
No full textCameron Simmons and Jeremy Farrar discuss the changing patterns of dengue epidemiology and the implications for clinical management and vaccines, drawing upon a recent study by Derek Cummings and colleagues in Thailand
Deformation density studies of ring systems. 2. The deformation density of the diazirine ring in the X-ray structure of 3-[(p-Nitrophenoxy) methyl]-3-chlorodiazirine
No full textThe crystal structure and electron density of 3-[(p-nitrophenoxy)methyl]-3-chlorodiazirine have been analyzed using single crystal X-ray diffraction at 208 K with Mo K alpha radiation to a resolution of sin(theta(max))/lambda = 1.126 Angstrom(-1). A total of 10 440 measured reflections gave 7742 unique reflections with R(m) = 0.026. A multipole atomic density model was fitted to these reflections to give an R(F) = 0.0311. The deformation density of the phenyl portion of the compound is as expected. The dynamic deformation density of the diazirine ring, however, suggests that the bonding in the three-membered ring is a combination of the classical severely-strained cr bonding system with a significant contribution of a a donation from the N=N to an sp(2) carbon. This observation is placed in the context of similar proposals for the bonding in cyclopropanes.PT: J; CR: ALLEN FH, 1987, J CHEM SOC PERK T 2, S1 BAERT F, 1982, ACTA CRYSTALLOGR A, V38, P143 BATTAGLIA R, 1980, Z NATURFORSCH B, V35, P719 BLESSING R, ACA T, P26 CAMERON TS, 1992, J AM CHEM SOC, V114, P1889 CAMERON TS, 1994, J AM CHEM SOC, V116, P1211 CREMER D, 1985, J AM CHEM SOC, V107, P3800 CREMER D, 1985, J AM CHEM SOC, V107, P3811 DEWAR MJS, 1979, J AM CHEM SOC, V101, P783 DOMENICANO A, 1975, ACTA CRYSTALLOGR B, V31, P221 DUNITZ JD, 1983, HELV CHIM ACTA, V66, P123 HANSEN NK, 1978, ACTA CRYSTALLOGR A, V34, P909 HIRSHFELD FL, 1991, CRYST REV, V2, P169 LINDEN A, 1988, J ORG CHEM, V53, P1085 LIU MTH, 1986, J CHEM SOC PERK T 2, P211 SCHMIDT MW, 1990, QCPE B, V10, P52 SEILER P, 1988, HELV CHIM ACTA, V71, P2100 SMITH VH, 1977, ISRAEL J CHEM, V16, P87 SOUHASSOU M, 1992, J AM CHEM SOC, V114, P2371 STEINER T, 1993, ACTA CRYSTALLOGR A, V49, P379 STEVENS IDR, 1990, J CHEM SOC P2, P661 STEWART RF, 1969, J CHEM PHYS, V51, P4569 WALSH AD, 1949, T FARADAY SOC, V45, P179 WIBERG KB, 1987, J AM CHEM SOC, V109, P985; NR: 24; TC: 4; J9: J AMER CHEM SOC; PG: 7; GA: NV421Source type: Electronic(1
Learning Economics by Servicing: a Mexican Experience of Service-Learning in Microenterprises
No full textThis paper presents an experience of a service learning program in underprivileged Microenterprises. An aspect that turns out to be original as compared to other contributions in literature is the explicit assessment of the impact of the program on the enterprises, since most of the related studies focus on evaluating the students experience and impact on learning derived from participation. The paper suggests that service learning programs with the participation of college students can play an important role both in supporting disadvantaged microenterprises and in providing meaningful learning experiences to students.
Dynamics of plane partitions: Proof of the Cameron and Fon-Der-Flaass conjecture
No full textOne of the oldest outstanding problems in dynamical algebraic combinatorics is the following conjecture of P. Cameron and D. Fon-Der-Flaass (1995): consider a plane partition P in an box . Let denote the smallest plane partition containing the minimal elements of . Then if is prime, Cameron and Fon-Der-Flaass conjectured that the cardinality of the -orbit of P is always a multiple of p. This conjecture was established for by Cameron and Fon-Der-Flaass (1995) and for slightly smaller values of p in work of K. Dilks, J. Striker and the second author (2017). Our main theorem specializes to prove this conjecture in full generality
Distribution and evolution of starspots on the RS CVn binary II Pegasi in 2004
No full textThis work is supported by National Natural Science Foundation of China through grants Nos. 10373023, 10773027 and 11333006, Chinese Academy of Sciences through project KJCX2-YW-T24.We present Doppler images of RS CVn-type binary II Peg based on two data sets obtained in 2004 February and November. In order to improve signal-to-noise ratio and reliability,we apply least-squares deconvolution technique to calculate average profiles from 2032 photospheric absorption lines. Both of the resulting surface images show a wide latitude distribution of starspots. Most spots are concentrated at a high-latitude belt above 60° and a low-latitude belt near equator. The starspots evolved dramatically between two observing runs, which may indicate shorter time-scale evolution in this epoch, especially for low-latitude belt. There is no stable preferred active longitude that can be found in our images. We also find out a possible phenomenon that the intermediate-latitude spot migrated poleward and merged with the high-latitude spot to make it stronger, which may reveal a more complex behaviour of starspots on II Peg. A potential change of orbital ephemeris zero-point was detected. This may imply an orbital period change of II Peg like other active close binaries.Peer reviewe
Polymer-based treatments to control runoff, leachate and erosion from engineered slopes at Simfer Mine, Guinea, Africa
No full textIt is necessary to understand the erodibility and hydrological response of mine-site slope forming materials (SFMs), because of increasing awareness of the environmental impacts of mining. Steep engineered slopes in high intensity rainfall environments present a serious erosion risk. Temporary surface stabilisers, such as polyacrylamides (PAMs) and polyvinylacrylic latex (PVALs) are potentially cost effective erosion control solutions. In this study PAM and PVAL efficacy to reduce runoff, leachate and erosion was assessed at two application rates, with and without gypsum on SFMs from an iron ore mine in Guinea (West Africa). NSPASS (near-surface photogrammetry assessment of slope forming materials’ surface roughness) is a novel method that integrates digital image capture and GIS. It is shown to detect and quantify surface micro-relief changes of 2-3 mm, not visible to the naked eye.
As expected, soil and non-soil SFMs were significantly different in terms of their physical and chemical properties. Phase I of the study investigated the erodibility of ten SFMs, including soil, ore and waste-rock. The results indicate that the hydrological response to rainfall of most SFMs is to generate leachate. Weathered phyllite (PHY-WEA) is the most erodible SFM by both runoff and leachate. Multiple regression analysis demonstrated that magnetic susceptibility, mineralogy and dry aggregate distribution; parameters not commonly assessed in erosion studies, are important in explaining SFM erodibility and hydrological response.
Phase II evaluated critically the effectiveness of three commercially available polymer solutions (two PAMs and one PVAL) at reducing runoff, leachate and erosion from four of the most erodible SFMs identified in Phase I. The results indicate that some PAM and PVAL treatments significantly reduce runoff, leachate and erosion. Polymer efficacy is highly dependent on the physical and chemical properties of the SFM, as well as the mechanism of polymer to SFM adsorption. Increasing the application rate of select treatments lowered leachate volumes, runoff and leachate total sediment loads. Contrary to previous studies, gypsum amendments did not significantly improve polymer efficiency.
This research has added to our understanding of the erodibility and hydrological response of soil and non-soil SFMs. This is the first study to evaluate critically the efficacy of PVALs in controlling erosion from mine-site SFMs. Future studies should continue to optimise NSPASS performance in monitoring changes in surface micro-relief
Trigastrotheca Cameron
No full textTrigastrotheca Cameron Trigastrotheca Cameron (type species Trigastrotheca trilobata Cameron, 1906) Coelodontus Roman (type species Ichneumon costator Thunberg, 1822) synonymized by Quicke (1987) but see below. Odontopygia Enderlein (type species Odontopygia tridentata Enderlein [1918] 1920) Kenema van Achterberg (type species Kenema quickei van Achterberg, 1983) synonymized by Quicke (1987) The descriptions of Coelodontus and Odontopygia are only based on females and therefore share the unique modification of the 5th metasomal tergite of other Trigastrotheca species. Quicke & Stanton (2005) explained the nomenclatural difficulties posed by Roman’s (1912) ‘improvement’ of the name given by Thunberg for the type species of Coelodontus, and so proposed the replacement name T. romani. The genus Kenema was a genus described by van Achterberg (1983) based on a male specimen collected by the senior author near the town of Kenema in Sierra Leone. It was not known at that time that male Trigastrotheca lack the submedial emarginations of the 5th metasomal tergite that females have, but instead have a very elongate and densely sculptured 5th tergite. We have seen numerous, mixed-sex, series of specimens (from Africa) that shows that this is a simple sexual dimorphism. Unfortunately, several of the new species described below are known only from males, but examination of mixed-sex series of what are virtually certainly conspecifics, indicates that apart from the modified 5th metasomal tergite, morphological characters and colour patterns are not noticeably intra-specifically variable. We therefore feel confident in describing new species of two species herein based only on males, though this might not normally be sensible within the Braconinae. Interestingly, there is very little size variation within a species of Trigastrotheca irrespective of sex, and therefore they do not display the normal sexual dimorphism that so many other idiobiont parasitoids do (Quicke 2015). Female Trigastrotheca may be recognised by using the key to Old World braconine genera provided by Quicke (1987), and can be distinguished from all other braconines by the pair of submedial emarginations of the 5th metasomal tergite separated by a pointed medial protuberance (Figs 2, 6 B, C). Males lack this modification and instead have a strongly sculptured and elongate 5th metasomal tergite. This sexual dimorphism led van Achterberg (1983) to believe that a male Trigastrotheca actually represented a separate genus and described it as Kenema. Quicke (1987), having seen mixed-sex, apparently conspecific series from the same locality, synonymised Kenema with Trigastrotheca, but not before van Achterberg & Sigwalt (1987) had described a further species under the name of Kenema.Published as part of Quicke, Donald L. J., Butcher, Buntika A., Ranjith, A. P. & Belokobylskij, Sergey A., 2017, Revision of the non-Afrotropical species of Trigastrotheca Cameron (Hymenoptera: Braconidae: Braconinae) with descriptions of four new species, pp. 95-110 in Zootaxa 4242 (1) on pages 96-97, DOI: 10.11646/zootaxa.4242.1.5, http://zenodo.org/record/37602
Dengue diagnostics and therapeutic interventions in Viet Nam
No full textDengue is a major public health problem that affects tens of millions of people annually in tropical and sub-tropical countries. This acute viral infection happens to be severe and even life threatening but there is still no available drug or vaccine. Previous studies have noted early higher viral burden in patients who develop more severe symptoms suggesting that administration of a potent and safe antiviral may prevent progression to severe dengue. To verify this hypothesis, we have conducted the first RCT directed towards reducing the viral burden in vivo by administrating chloroquine (CQ), a cheap and well-tolerated drug that inhibits DENV in vitro with concentrations achievable in vivo, to 307 Vietnamese adults with suspected dengue (257 of them were laboratory-confirmed cases). Unfortunately, we did not see an effect of CQ on the duration of infection. However in patients treated with CQ, we observed a trend towards a lower incidence of severe forms. We did not find any differences in the immune response that can explain this trend. We also found more adverse events, primarily vomiting, with CQ. In addition, we have explored the relationships between clinical features, antibody responses and virological markers in these patients. We found that the early magnitude of viremia is positively associated with disease severity and there are serotype dependent differences in infection kinetics. We found as well that DENV was cleared faster and earlier in patients with secondary infections. To complete this study, we have also evaluated 2 rapid lateral flow tests for the diagnosis of dengue in a panel of plasma samples from 245 RT-PCR confirmed dengue patients and 47 with other febrile illnesses. Our data suggest that the NS1 test component of these tests are highly specific and have similar levels of sensitivity (~60%). Both NS1 assays were significantly more sensitive for primary than secondary dengue. The IgM parameter in the SD Duo test improved overall test sensitivity without compromising specificity. All these findings are of major importance for further anti-viral drug testing
The pathogenesis of dengue.
No full textDengue is an important cause of childhood and adult morbidity in Asian and Latin American countries and its geographic footprint is growing. The clinical manifestations of dengue are the expression of a constellation of host and viral factors, some acquired, others intrinsic to the individual. The virulence of the virus plus the flavivirus infection history, age, gender and genotype of the host all appear to help shape the severity of infection. Similarly, the characteristics of the innate and acquired host immune response subsequent to infection are also likely determinants of outcome. This review summarises recent developments in the understanding of dengue pathogenesis and their relevance to dengue vaccine development
'Sorry to have kept you waiting so long, Mr Macfarlane': Further education after the Coalition
No full textThis chapter focuses on the further education (FE) sector in England. Initially it gives an overview of the ‘condition’ of the FE sector and summarises of some of the main characteristics of the current Government’s approach to further education. The chapter locates the Coalition’s position on FE, and some of the key initiatives associated with this stance, within a broader social, economic and cultural context, before turning to the future of further education. Whilst I acknowledge that much will need to be done across all sectors of education after the Coalition loses power, it is argued that no one part of the education system – if indeed system is the correct term – operates in isolation; and that FE’s role and remit is strongly influenced, not only by the nature of the labour market and the economy more broadly, but by the relative status and position of universities, schools and other providers of education and training. Drawing on the ideals of the comprehensive movement and some of the recommendations made in the first draft of the often forgotten Macfarlane Report, the remainder of the chapter provides a vision for further education after the coalition by arguing that FE needs to be repositioned at the heart of a coherent system of tertiary education and play a key role in integrating academic with vocational learning. It finishes by offering a critical overview of the far-reaching cultural, structural and curricular changes that would be required, not only within the further education sector, but across other parts of the compulsory and post-compulsory education system, in order to enable this
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