45,144 research outputs found

    Information Systems Undergraduate Degree Project: Gaining a Better Understanding of the Final Year Project Module

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    The place of an individual project in the final year of Information Systems (IS) undergraduate degrees at UK universities is well established. In this paper we compare the final year project modules at four UK universities: the University of Brighton, the University of South Wales, University of West London and the University of Westminster. We find that the aims of the projects are similar, emphasising the application of the knowledge and skills from the taught element of their course in a complex development project, often including interactions with a real client. Although we show in this analysis that projects serve a similar purpose in the IS degree courses, the associated learning outcomes and the assessment practice varies across the institutions. We identify some gaps in the skills and abilities that are not being assessed. In further work we are planning to consult final year students undertaking their projects and their supervisors, in order to gain an understanding of how project assessment criteria are actually put to use

    Dark Matter in the USSM

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    We discuss the neutralino dark matter within classes of extended supersymmetric models, referred to as the USSM, containing one additional SM singlet Higgs plus an extra Z', together with their superpartners the singlino and bino'.Comment: 4 pages, 3 figs. Talk given at LCWS08, Chicago, IL, USA, 11/16-20/200

    A clinically relevant model of osteoinduction: a process requiring calcium phosphate and BMP/Wnt signalling

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    In this study, we investigated a clinically relevant model of in vivo ectopic bone formation utilizing human periosteum derived cells (HPDCs) seeded in a Collagraft carrier and explored the mechanisms by which this process is driven. Bone formation occurred after eight weeks when a minimum of one million HPDCs was loaded on Collagraft carriers and implanted subcutaneously in NMRI nu/nu mice. De novo bone matrix, mainly secreted by the HPDCs, was found juxta-proximal of the calcium phosphate (CaP) granules suggesting that CaP may have triggered the 'osteoinductive program'. Indeed, removal of the CaP granules by ethylenediaminetetraacetic acid decalcification prior to cell seeding and implantation resulted in loss of bone formation. In addition, inhibition of endogenous bone morphogenetic protein and Wnt signalling by overexpression of the secreted antagonists Noggin and Frzb, respectively, also abrogated osteoinduction. Proliferation of the engrafted HPDCs was strongly reduced in the decalcified scaffolds or when seeded with adenovirus-Noggin/Frzb transduced HPDCs indicating that cell division of the engrafted HPDCs is required for the direct bone formation cascade. These data suggest that this model of bone formation is similar to that observed during physiological intramembranous bone development and may be of importance when investigating tissue engineering strategies.Published versio

    The Toxoplasma gondii plastid replication and repair enzyme complex, PREX

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    A plastid-like organelle, the apicoplast, is essential to the majority of medically and veterinary important apicomplexan protozoa including Toxoplasma gondii and Plasmodium. The apicoplast contains multiple copies of a 35 kb genome, the replication of which is dependent upon nuclear-encoded proteins that are imported into the organelle. In P. falciparum an unusual multi-functional gene, pfprex, was previously identified and inferred to encode a protein with DNA primase, DNA helicase and DNA polymerase activities. Herein, we report the presence of a prex orthologue in T. gondii. The protein is predicted to have a bi-partite apicoplast targeting sequence similar to that demonstrated on the PfPREX polypeptide, capable of delivering marker proteins to the apicoplast. Unlike the P. falciparum gene that is devoid of introns, the T. gondii prex gene carries 19 introns, which are spliced to produce a contiguous mRNA. Bacterial expression of the polymerase domain reveals the protein to be active. Consistent with the reported absence of a plastid in Cryptosporidium species, in silico analysis of their genomes failed to demonstrate an orthologue of prex. These studies indicate that prex is conserved across the plastid-bearing apicomplexans and may play an important role in the replication of the plastid genome

    Induced encystment improves resistance to preservation and storage of Acanthamoeba castellanii

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    Several conditions that allow the preservation, storage and rapid, efficient recovery of viable Acanthamoeba castellanii organisms were investigated. The viability of trophozoites (as determined by time to confluence) significantly declined over a period of 12 months when stored at −70°C using dimethyl sulfoxide (DMSO; 5 or 10%) as cryopreservant. As A. castellanii are naturally capable of encystment, studies were undertaken to determine whether induced encystment might improve the viability of organisms under a number of storage conditions. A. castellanii cysts stored in the presence of Mg2+ at 4°C remained viable over the study period, although time to confluence was increased from approximately 8 days to approximately 24 days over the 12-month period. Storage of cysts at −70°C with DMSO (5 or 10%) or 40% glycerol, but not 80% glycerol as cryopreservants increased their viability over the 12-month study period compared with those stored at room temperature. Continued presence of Mg2+ in medium during storage had no adverse effects and generally improved recovery of viable organisms. The present study demonstrates that A. castellanii can be stored as a non-multiplicative form inexpensively, without a need for cryopreservation, for at least 12 months, but viability is increased by storage at −70°C

    New biostratigraphic, magnetostratigraphic and isotopic insights into the Middle Eocene Climatic Optimum in low latitudes

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    The Middle Eocene Climatic Optimum (MECO) was a warming event that interrupted the long-term Eocene cooling trend. While this event is well documented at high southern and mid-latitudes, it is poorly known from low latitudes and its timing and duration are not well constrained because of problems of hiati, microfossil preservation and weak magnetic polarity in key sedimentary sections. Here, we report the results of a study designed to improve the bio-, magneto- and chemostratigraphy of the MECO interval using high-resolution records from two low-latitude sections in the Atlantic Ocean, Ocean Drilling Program (ODP) Sites 1051 and 1260. We present the first detailed benthic foraminiferal stable isotope records of the MECO from the low latitudes as well as the biostratigraphic counts of Orbulinoides beckmanni and new magnetostratigraphic results. Our data demonstrate a ~ 750 kyr-long duration for the MECO characterized by increasing δ13C and decreasing δ18O, with minimum δ18O values lasting ~ 40 kyr at 40.1 Ma coincident with a short-lived negative δ13C excursion. Thereafter, δ18O and δ13C values recover rapidly. The shift to minimum δ18O values at 40.1 Ma is coincident with a marked increase in the abundance of the planktonic foraminifera O. beckmanni, consistent with its inferred warm-water preference. O. beckmanni is an important Eocene biostratigraphic marker, defining planktonic foraminiferal Zone E12 with its lowest and highest occurrences (LO and HOs). Our new records reveal that the LO of O. beckmanni is distinctly diachronous, appearing ~ 500 kyr earlier in the equatorial Atlantic than in the subtropics (40.5 versus 41.0 Ma). We also show that, at both sites, the HO of O. beckmanni at 39.5 Ma is younger than the published calibrations, increasing the duration of Zone E12 by at least 400 kyr. In accordance with the tropical origins of O. beckmanni, this range expansion to higher latitudes may have occurred in response to sea surface warming during the MECO and subsequently disappeared with cooling of surface waters

    Hot Electron Capture Dissociation Distinguishes Leucine from Isoleucine in a Novel Hemoglobin Variant, Hb Askew, β54(D5)Val→Ile

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    Population migration has led to the global dispersion of human hemoglobinopathies and has precipitated a need for their identification. An effective mass spectrometry-based procedure involves analysis of the intact α- and β-globin chains to determine their mass, followed by location of the variant amino acid residue by direct analysis of the enzymatically digested chains and low-energy collision induced dissociation of the variant peptide. Using this procedure, a variant was identified as either β54Val→Leu or β54Val→Ile, since the amino acids leucine and isoleucine cannot be distinguished using low-energy collisions. Here, we describe how hot electron capture dissociation on a Fourier transform-ion cyclotron resonance mass spectrometer was used to distinguish isoleucine from leucine and identify the mutation as β54(D5)Val→Ile. This is a novel variant, and we have named it Hb Askew

    A Gaussian process framework for modelling instrumental systematics: application to transmission spectroscopy

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    Transmission spectroscopy, which consists of measuring the wavelength-dependent absorption of starlight by a planet's atmosphere during a transit, is a powerful probe of atmospheric composition. However, the expected signal is typically orders of magnitude smaller than instrumental systematics, and the results are crucially dependent on the treatment of the latter. In this paper, we propose a new method to infer transit parameters in the presence of systematic noise using Gaussian processes, a technique widely used in the machine learning community for Bayesian regression and classification problems. Our method makes use of auxiliary information about the state of the instrument, but does so in a non-parametric manner, without imposing a specific dependence of the systematics on the instrumental parameters, and naturally allows for the correlated nature of the noise. We give an example application of the method to archival NICMOS transmission spectroscopy of the hot Jupiter HD 189733, which goes some way towards reconciling the controversy surrounding this dataset in the literature. Finally, we provide an appendix giving a general introduction to Gaussian processes for regression, in order to encourage their application to a wider range of problems.Comment: 6 figures, 1 table, accepted for publication in MNRA

    X-Ray Observations of Black Widow Pulsars

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    We describe the first X-ray observations of five short orbital period (PB<1P_B < 1 day), γ\gamma-ray emitting, binary millisecond pulsars. Four of these, PSRs J0023+0923, J1124-3653, J1810+1744, and J2256-1024 are `black-widow' pulsars, with degenerate companions of mass 0.1M\ll0.1 M_{\odot}, three of which exhibit radio eclipses. The fifth source, PSR J2215+5135, is an eclipsing `redback' with a near Roche-lobe filling \sim0.2 solar mass non-degenerate companion. Data were taken using the \textit{Chandra X-Ray Observatory} and covered a full binary orbit for each pulsar. Two pulsars, PSRs J2215+5135 and J2256-1024, show significant orbital variability while PSR J1124-3653 shows marginal orbital variability. The lightcurves for these three pulsars have X-ray flux minima coinciding with the phases of the radio eclipses. This phenomenon is consistent with an intrabinary shock emission interpretation for the X-rays. The other two pulsars, PSRs J0023+0923 and J1810+1744, are fainter and do not demonstrate variability at a level we can detect in these data. All five spectra are fit with three separate models: a power-law model, a blackbody model, and a combined model with both power-law and blackbody components. The preferred spectral fits yield power-law indices that range from 1.3 to 3.2 and blackbody temperatures in the hundreds of eV. The spectrum for PSR J2215+5135 shows a significant hard X-ray component, with a large number of counts above 2 keV, which is additional evidence for the presence of intrabinary shock emission and is similar to what has been detected in the low-mass X-ray binary to millisecond pulsar transition object PSR J1023+0038.Comment: 8 pages, 6 figures, 2 tables, submitted to Ap
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