15 results on '"Fenech, Thomas"'
Search Results
2. Forces between nanoparticles in a nematic host : a simulation study
- Author
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Fenech, Thomas Joseph William
- Subjects
530.4 - Abstract
Colloidal dispersions in a nematic liquid crystal host are an emerging system in soft matter. They are of fundamental interest due to the long range interactions that the liquid crystal mediates between the colloidal particles. It has been shown that these interactions can result in self-assembly of colloidal crystal structures, which has great potential in the creation of a new class of metamaterials. Although nematic liquid crystals are a mature field of research, there is still a great deal that remains unknown regarding their role in governing the interaction between colloidal particles. Analytical solutions can only predict the behaviour of the system in the most simple of cases. In order to understand experimental observations and predict the behaviour of novel systems, numerical simulations are an essential tool. As the complexity of the system increases, so too does the computational expense of modelling it. Previous numerical studies have often focused on a very specific problem, relying on the ability to reduce it to a more simple one via symmetry arguments. While this is a useful means of analysing a given case, it leads to a model that is inflexible. If one is to develop a more general-purpose tool to study a wider variety of systems, a crucial consideration is the performance. In order to harness the full potential of modern computers, it is essential to expose the maximum degree of parallelism in a given problem. In this work, an existing algorithm used to model nematic liquid crystals has been ported to a platform that is capable of fully exploiting the levels of parallelism in modern computing systems. This has facilitated the study of systems much larger than could previously be simulated within reasonable time frames.
- Published
- 2015
3. Benchmarking Elastic Cloud Big Data Services Under SLA Constraints
- Author
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Poggi, Nicolas, primary, Cuevas-Vicenttín, Víctor, additional, Berral, Josep Lluis, additional, Fenech, Thomas, additional, Gómez, Gonzalo, additional, Brini, Davide, additional, Montero, Alejandro, additional, Carrera, David, additional, Minhas, Umar Farooq, additional, Blakeley, Jose A., additional, Kossmann, Donald, additional, Ramakrishnan, Raghu, additional, and Szyperski, Clemens, additional
- Published
- 2020
- Full Text
- View/download PDF
4. The longest ocular axial length ever recorded?
- Author
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Vassallo, James and Fenech, Thomas
- Subjects
genetic structures ,Eye -- Abnormalities -- Case studies ,Retinal detachment ,Eye -- Ultrasonic imaging ,sense organs ,eye diseases - Abstract
A brief case report of extremely long ocular axial length (AL) is being reported. Contact a-scan ultrasound gave a mean AL of 38.34mm. To the best of our knowledge, this is the longest reported AL of a human eye. 15mls of silicone oil were needed to fill the vitreous cavity during surgery for retinal detachment., peer-reviewed
- Published
- 2020
5. Experimental transplantation of human retinal pigment epithelial cells on collagen substrates
- Author
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Bhatt, Nitul S., Newsome, David A., Fenech, Thomas, Hessburg, Thomas P., Diamond, James G., Miceli, Michael V., Kratz, Kenneth E., and Oliver, Peter D.
- Subjects
Rhodopsin -- Physiological aspects ,Transplantation of organs, tissues, etc. -- Research ,Health - Published
- 1994
6. Assessing the analgesic benefit of phacoemulsification under topical anesthesia using pre-operative nepafenac 0.1%
- Author
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Fenech, Thomas and Fenech, Matthew T.
- Subjects
Phacoemulsification ,genetic structures ,Nonsteroidal anti-inflammatory agents ,Cataract -- Surgery ,Myopia - Abstract
Background: To compare the intra-operative analgesic benefit of cataract surgery under topical anesthesia with and without pre-operative NSAIDs, namely nepafenac 0.1% (Alcon Laboratories Inc, Nevanec® , Fort Worth, TX, USA) Method: In a study carried out at Mater Dei Hospital, Ophthalmic department, Malta, 199 patients with a cataract were divided into two groups. 100 eyes received nepafenac 0.1% pre-operatively while 99 eyes did not. Intra-operative discomfort was judged by assessing facial grimacing, restlessness, irritability and distress and the results were noted. Patients were divided into refractive error groups, namely myopic, hypermetropic and emmetropic. Results: Pre-operative nepafenac 0.1% produced significantly more pain free cataract surgeries, resulting in a discomfort rate of 9% vs 28% in the group where pre-operative nepafenac 0.1% was not used. Pain was also most evidently observed on insertion of the phaco handpiece. This may be said for patients in all refractive errors groups. Conclusions: The analgesic efficacy of nepafenac 0.1% pre-operatively is significant in reduced intra-operative discomfort during cataract surgery repair under topical analgesia., peer-reviewed
- Published
- 2017
7. A retrospective study on the Maltese population of the outcome of retinal detachment repair after the removal of silicone oil
- Author
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Fenech, Matthew T., Fenech, Thomas, and Diamond, James G.
- Subjects
Retinal detachment -- Malta -- Case studies ,Retinal detachment -- Malta -- Surgery -- Case studies ,Silicones in surgery - Abstract
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-reviewed
- Published
- 2016
8. Sudden bilateral loss of vision in a 19-year-old man
- Author
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Pirotta, Suzanne T., Sciriha, Gabriella M., Cauchi, David, Vassallo, James, and Fenech, Thomas
- Subjects
Vision disorders ,Hypertension ,Reversible Posterior Leukoencephalopathy Syndrome - Abstract
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-reviewed
- Published
- 2015
9. Primary CNS lymphoma with intravitreal metastasis : using vitreous cavity samples to monitor response to therapy
- Author
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Fenech, Matthew T., Aquilina, Nicola, Grech Hardie, John, Pirotta, Suzanne T., Fenech, Thomas, and Debono, Patricia
- Subjects
sense organs ,eye diseases ,Lymphomas -- Case studies ,Vitrectomy -- Case studies - Abstract
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-reviewed
- Published
- 2015
10. Orbital pseudotumour masquerading as Wegener’s granulomatosis
- Author
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Fenech, Matthew T. and Fenech, Thomas
- Subjects
Eye -- Diseases -- Casestudies ,Wegener's granulomatosis -- Case studies ,eye diseases - Abstract
A twenty-two year old female patient presented with new onset bilateral hard orbital masses and progressively worse tear lake problems. Computed tomography of the orbits revealed poorly differentiated bilateral orbital masses. Laboratory investigation revealed ANCA positivity. Routine biochemical investigations were all within normal limits. CXR was also normal. Biopsy of the orbital masses revealed non-specific histological findings. An initial diagnosis of Granulomatosis with Polyangitis (GPA) was postulated. Oral steroids were given followed by a rapid response to steroid therapy. The working diagnosis of GPA was abandoned and a diagnosis of idiopathic orbital inflammation (IOI), or orbital pseudotumour was made owing to the benign, non-infective, inflammatory pathology with no evident systemic or local cause. Tailoring off of steroids resulted in repeated flare ups, resulting in the initiation of methotrexate therapy. The patient is in remission and is currently on combined steroid and methotrexate treatment. IOI is a diagnosis of exclusion and a rapid response to steroids serves as a diagnostic aid but is not in itself diagnostic., peer-reviewed
- Published
- 2015
11. The state of SQL-on-Hadoop in the cloud
- Author
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Universitat Politècnica de Catalunya. Departament d'Arquitectura de Computadors, Barcelona Supercomputing Center, Universitat Politècnica de Catalunya. CAP - Grup de Computació d'Altes Prestacions, Poggi, Nicolas, Berral García, Josep Lluís, Fenech, Thomas, Carrera Pérez, David, Blakeley, Jose, Minhas, Umar F., Vujic, Nikola, Universitat Politècnica de Catalunya. Departament d'Arquitectura de Computadors, Barcelona Supercomputing Center, Universitat Politècnica de Catalunya. CAP - Grup de Computació d'Altes Prestacions, Poggi, Nicolas, Berral García, Josep Lluís, Fenech, Thomas, Carrera Pérez, David, Blakeley, Jose, Minhas, Umar F., and Vujic, Nikola
- Abstract
Managed Hadoop in the cloud, especially SQL-on-Hadoop, has been gaining attention recently. On Platform-as-a-Service (PaaS), analytical services like Hive and Spark come preconfigured for general-purpose and ready to use. Thus, giving companies a quick entry and on-demand deployment of ready SQL-like solutions for their big data needs. This study evaluates cloud services from an end-user perspective, comparing providers including: Microsoft Azure, Amazon Web Services, Google Cloud, and Rackspace. The study focuses on performance, readiness, scalability, and cost-effectiveness of the different solutions at entry/test level clusters sizes. Results are based on over 15,000 Hive queries derived from the industry standard TPC-H benchmark. The study is framed within the ALOJA research project, which features an open source benchmarking and analysis platform that has been recently extended to support SQL-on-Hadoop engines. The ALOJA Project aims to lower the total cost of ownership (TCO) of big data deployments and study their performance characteristics for optimization. The study benchmarks cloud providers across a diverse range instance types, and uses input data scales from 1GB to 1TB, in order to survey the popular entry-level PaaS SQL-on-Hadoop solutions, thereby establishing a common results-base upon which subsequent research can be carried out by the project. Initial results already show the main performance trends to both hardware and software configuration, pricing, similarities and architectural differences of the evaluated PaaS solutions. Whereas some providers focus on decoupling storage and computing resources while offering network-based elastic storage, others choose to keep the local processing model from Hadoop for high performance, but reducing flexibility. Results also show the importance of application-level tuning and how keeping up-to-date hardware and software stacks can influence performance even more than replicating the on-premises model in the, This work is partially supported by the Microsoft Azure for Research program, the European Research Council (ERC) under the EUs Horizon 2020 programme (GA 639595), the Spanish Ministry of Education (TIN2015-65316-P), and the Generalitat de Catalunya (2014-SGR-1051)., Peer Reviewed, Postprint (author's final draft)
- Published
- 2016
12. The state of SQL-on-Hadoop in the cloud
- Author
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Poggi, Nicolas, primary, Berral, Josep Ll., additional, Fenech, Thomas, additional, Carrera, David, additional, Blakeley, Jose, additional, Minhas, Umar Farooq, additional, and Vujic, Nikola, additional
- Published
- 2016
- Full Text
- View/download PDF
13. Primary CNS Lymphoma with Intravitreal Metastasis - using vitreous cavity samples to monitor response to therapy.
- Author
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Fenech, Matthew, Aquilina, Nicola, Hardie, John Grech, Pirotta, Suzanne, Fenech, Thomas, and Debono, Patricia
- Subjects
LYMPHOMA treatment ,STEROID drugs ,VITRECTOMY ,THERAPEUTICS - Abstract
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. [ABSTRACT FROM AUTHOR]
- Published
- 2015
14. Sudden bilateral loss of vision in a 19-year-old man.
- Author
-
Pirotta, Suzanne, Sciriha, Gabriella, Cauchi, David, Vassallo, James, and Fenech, Thomas
- Subjects
LEUKOENCEPHALOPATHIES ,HYPERTENSION ,PATIENTS - Abstract
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. [ABSTRACT FROM AUTHOR]
- Published
- 2015
15. Orbital Pseudotumour Masquerading as Wegener's Granulomatosis.
- Author
-
Fenech, Matthew and Fenech, Thomas
- Subjects
- *
VASCULITIS - Abstract
A twenty-two year old female patient presented with new onset bilateral hard orbital masses and progressively worse tear lake problems. Computed tomography of the orbits revealed poorly differentiated bilateral orbital masses. Laboratory investigation revealed ANCA positivity. Routine biochemical investigations were all within normal limits. CXR was also normal. Biopsy of the orbital masses revealed non-specific histological findings. An initial diagnosis of Granulomatosis with Polyangitis (GPA) was postulated. Oral steroids were given followed by a rapid response to steroid therapy. The working diagnosis of GPA was abandoned and a diagnosis of idiopathic orbital inflammation (IOI), or orbital pseudotumour was made owing to the benign, non-infective, inflammatory pathology with no evident systemic or local cause. Tailoring off of steroids resulted in repeated flare ups, resulting in the initiation of methotrexate therapy. The patient is in remission and is currently on combined steroid and methotrexate treatment. IOI is a diagnosis of exclusion and a rapid response to steroids serves as a diagnostic aid but is not in itself diagnostic. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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