Primary CNS lymphoma with intravitreal metastasis : using vitreous cavity samples to monitor response to therapy

A fifty-eight year old male patient presented to the ophthalmic department with a 3 day history of reduced visual acuity, blurred vision and floaters, associated with recent lethargy, headaches and behavioural changes. Fundal examination revealed a bilateral vitritis. Steroid therapy was started. MRI of the brain revealed multiple hypodense and hyperdense lesions. Vitrectomy was performed in view of the poor response to steroids. A biopsy showed non-hodgkin B-Cell lymphoma. The patient was started on intravenous Methotrexate and Cytarabine. Repeat vitreous cavity biopsies were performed in order to assess response to therapy. All biopsies to date have revealed evidence of on-going lymphoma.peer-reviewe

Sale the seven Cs: Teaching/training aid for the (e-)retail mix

The ‘4Ps’ of the marketing mix have long been popular with students, tutors, trainers and practitioners as a learning and teaching aid. The purpose of this paper is to present an equivalent tool for retail and e-retail: ‘Sale the 7Cs’. The approach is by reference to other authors’ versions of the marketing, retail and e-retail mixes, distilled into a simplified framework: C1 Convenience; C2 Customer value and benefit; C3 Cost to the customer; C4 Computing and category management; C5 Customer franchise; C6 Customer care and service; C7 Communication and customer relationships. This simplified mnemonic is new for (e-)retail. Mini case examples are used to illustrate the applicability. These have a practical value for trainers and educators as specimen answers to activity exercises. Retailers may find the convenient 7Cs structure useful when planning strategies and tactics

A retrospective study on the Maltese population of the outcome of retinal detachment repair after the removal of silicone oil

Background: Silicone oils of different viscosities are used in the treatment of retinal detachments of varying pathology. Method: Seventy-two cases of retinal detachments managed with silicone oil were reviewed in a retrospective chart analyses. Eighty nine patients were reviewed from which data on primary pathology, type of silicone oil, duration of oil “in situ” and complications (including emulsification, increased intraocular pressure (IOP), re-detachment, cataract and presence of CME) were compiled. Of this number, 72 patients with post- operative follow-up of two years or more and documentation of the above parameters were included. The data was carefully analysed in an effort to determine the primary factor or factors of the varying silicone oil substitutes utilized responsible for the successful or non-successful re- attachment of the retina. Results: Retinal re-detachment rate is greater when Silicone Oil (SO) is removed before 12 months. Complex vs non-complex retinal re- detachments in sub-group analysis indicates superiority of retention of SO for greater than 12 months. Emulsification is greater in low viscosity SO (1300cts). Conclusion: The complication rates witnessed in this retrospective study are comparable to the findings of published studies present in the ophthalmic literature on an international scale. The findings of this study support the hypothesis that it is the duration of the SO “in situ” as opposed to the viscosity or other SO attributes which ultimately influences the re-detachment rate.peer-reviewe

Sudden bilateral loss of vision in a 19-year-old man

Introduction: Posterior Reversible Leukoencephalopathy Syndrome (PRES) is caused by ischaemia commonly affecting the posterior cerebral vasculature. It presents with sudden decreased vision, headaches, nausea, vomiting, seizures, and altered mental status. Case presentation: A 19-year-old male presented to the ophthalmic emergency complaining of sudden bilateral loss of vision, which was down to light perception He reported headaches, nausea, and drowsiness since the previous day. He was a known case of hypertension secondary to IgA nephropathy. Magnetic resonance imaging (MRI) with STIR and FLAIR sequences showed foci of hyperintensity within the occipital lobes bilaterally. This confirmed the suspected diagnosis of PRES. Discussion: Aetiological factors of PRES include sudden increase in blood pressure, eclampsia, porphyria, renal disease, and Cushing syndrome. These lead to blood-brain barrier injury either by hyper- or hypoperfusion, endothelial dysfunction, changes in blood vessel morphology, hypocapnea, or immune system activation. Histopathological changes in PRES include activated astrocytes, scattered macrophages and lymphocytes, often in the absence of inflammation or neuronal damage. Conclusion: PRES is usually a reversible neuroophthalmological condition, however prompt recognition and appropriate management is important to prevent permanent brain injury or even death.peer-reviewe

Deep MERLIN 5GHz Radio Imaging of Supernova Remnants in the M82 Starburst

The results of an extremely deep, 8-day long observation of the central kpc of the nearby starburst galaxy M82 using MERLIN (Multi-Element Radio Linked Interferometer Network) at 5 GHz are presented. The 17E-06 Jy/beam, rms noise level in the naturally weighted image make it the most sensitive high resolution radio image of M82 made to date. Over 50 discrete sources are detected, the majority of which are supernova remnants, but with 13 identified as HII regions. Sizes, flux densities and radio brightnesses are given for all of the detected sources, which are all well resolved with a majority showing shell or partial shell structures. Those sources within the sample which are supernova remnants have diameters ranging from 0.3 to 6.7 pc, with a mean size of 2.9 pc. From a comparison with previous MERLIN 5 GHz observations made in July 1992, which gives a 9.75 year timeline, it has been possible to measure the expansion velocities of ten of the more compact sources, eight of which have not been measured before. These derived expansion velocities range between 2200 and 10500 km/s.Comment: 34 pages, 10 figures. Accepted by MNRA

Thermodynamics of an attractive 2D Fermi gas

Thermodynamic properties of matter are conveniently expressed as functional relations between variables known as equations of state. Here we experimentally determine the compressibility, density and pressure equations of state for an attractive 2D Fermi gas in the normal phase as a function of temperature and interaction strength. In 2D, interacting gases exhibit qualitatively different features to those found in 3D. This is evident in the normalized density equation of state, which peaks at intermediate densities corresponding to the crossover from classical to quantum behaviour.Comment: Contains minor revision

Satellite multiple access protocols for land mobile terminals. A study of the multiple access environment for land mobile satellite terminals, including the design analysis and simulation of a suitable protocol and the evaluation of its performance in a U.K. system.

This thesis is a study of multiple access schemes for satellite land mobile systems that provide a domestic or regional service to a large number of small terminals. Three orbit options are studied, namely the geostationary, elliptical (Molniya) and inclined circular orbits. These are investigated for various mobile applications and the choice of the Molniya orbit is justified for a U. K. system. Frequency, Time and Code Division Multiple Access (FDMA, TDMA and CDMA) are studied and their relative merits in the mobile environment are highlighted. A hybrid TDMA/FDMA structure is suggested for a large system. Reservation ALOHA schemes are appraised in a TDMA environment and an adaptive reservation multiple access protocol is proposed and analysed for a wide range of mobile communication traffic profiles. The system can cope with short and long data messages as well as voice calls. Various protocol options are presented and a target system having 100,000 users is considered. Analyses are presented for the steady state of protocols employing pure and slotted ALOHA and for the stabilty of the slotted variant, while simulation techniques were employed to validate the steady state analysis of the slotted ALOHA protocol and to analyse the stability problem of the pure ALOHA version. An innovative technique is put forward to integrate the reservation and the acquisition processes. It employs the geographical spread of the users to form part of the random delay in P-ALOHA. Finally an economic feasibility study is performed for the spacesegment. For costs of capital (r) less than 23 % the discounted payback period is less than the project's lifetime (10 years). At r- 8% the payback period is about 5.6 years, while the internal-rate-of-return is 22.2 %. The net present value at the end of the projects lifetime is £M 70 at r-8%

High-velocity-resolution observations of OH main line lasers in the M82 starburst

Using the VLA, a series of high velocity resolution observations have been made of the M82 starburst at 1.6 GHz. These observations follow up on previous studies of the main line OH maser emission in the central kiloparsec of this starburst region, but with far greater velocity resolution, showing significant velocity structure in some of the maser spots for the first time. A total of thirteen masers were detected, including all but one of the previously known sources. While some of these masers are still unresolved in velocity, these new results clearly show velocity structure in spectra from several of the maser regions. Position-velocity plots show good agreement with the distribution of H{\sc i} including interesting velocity structure on the blueward feature in the west of the starburst which traces the velocity distribution seen in the ionised gas.Comment: MNRAS in press. 15 pages, 9 figure

OH masers in nearby galaxies

Using the VLA, a series of high velocity resolution observations have been made of the M82 starburst. These observations follow up on previous studies of the main line OH maser emission in the central kiloparsec of this starburst region, but with greater velocity resolution than previous observations. A total of thirteen masers were detected, including all but one of the previously known sources. These new results clearly show velocity structure in spectra from several of the maser regions. Position-velocity plots show good agreement with the distribution of HI including interesting velocity structure on the blue-ward feature in the west of the starburst which traces the velocity distribution seen in the ionised gas as traced by [NeII] for example