260 research outputs found
Cosmological Evolution in a Type-0 String Theory
We study the cosmological evolution of a type-0 string theory by employing
non-criticality, which may be induced by fluctuations of the D3 brane worlds.
We check the consistency of the approach to O(alpha ') in the corresponding
sigma-model. The ten-dimensional theory is reduced to an effective
four-dimensional model, with only time dependent fields. We show that the
four-dimensional universe has an inflationary phase and graceful exit from it,
while the other extra dimensions are stabilized to a constant value, with the
fifth dimension much larger than the others. We pay particular attention to
demonstrating the role of tachyonic matter in inducing these features. The
Universe asymptotes, for large times, to a non-accelerating linearly-expanding
Universe with a time-dependent dilaton and a relaxing to zero vacuum energy a
la quintessence.Comment: 33 pages LATEX, seven eps figures incorporate
Isolated descemetorhexis for anterior synechiolysis prior to endothelial keratoplasty - case report and technique.
To describe the utilization of descemetorhexis for reformation of the anterior chamber in eyes with central iridocorneal synechiae before endothelial keratoplasty (EK).
A 71-year-old man with a history of trabeculectomy complicated by hypotony presented with bullous keratopathy in the presence of extensive iridocorneal synechiae and a flat anterior chamber. In order to proceed with EK, synechiolysis with the use of viscoelastic and scissors was attempted. Despite successful dissection of the peripheral strands, the pupillary margin of the iris remained attached to the endothelium. Therefore, descemetorhexis was performed to detach the Descemet membrane along with central synechiae and create sufficient space for safe EK at a later stage.
Corneal clarity was restored by ultrathin Descemet stripping automated endothelial keratoplasty, leaving a fibrous membrane in the pupillary plane, which was excised 2 months later, allowing an improvement of best-corrected visual acuity to 0.5.
Isolated descemetorhexis was successfully employed to reform the anterior chamber and proceed with EK in a case of bullous keratopathy and resistant iridocorneal synechiae. This stepwise approach may be considered in similar cases in order to avoid a more invasive treatment, ie, penetrating keratoplasty and synechiolysis
Photodynamic therapy of choroidal neovascularization with enlargement of the spot size to include the feeding complex
This is a case report of a 83-year-old man with choroidal neovascularization (CNV), due to age-related macular degeneration (AMD) in his right eye. Digital fluorescein (FA) and indocyanine green angiography (ICG) were performed, which disclosed predominantly classic subfoveal CNV and a dilated and tortuous feeding complex. The visual acuity was 20/800. Anti-vascular endothelial growth factor (anti-VEGF) treatment was suggested, however, the patient was not keen to receive an intraocular injection. Modified photodynamic therapy (PDT) with spot size enlarged, to include not only the CNV lesion but the feeding complex as well, was performed. Ten days after one session of PDT, ICG showed absence of leakage from the CNV and complete occlusion of the feeding complex. The visual acuity gradually improved to 20/100 and remained stable during the following 23 months. No evidence of CNV leakage was seen in the FA and ICG during the follow up period. Adjustment of the PDT spot size to include the detectable by ICG feeding complex might be an additional option in order to close the subfoveal CNV and might be considered as an alternative to intravitreal injection of anti-VEGF in selected cases where anti-VEGF treatment is not available
Skin rash associated with intravitreal bevacizumab in a patient with macular choroidal neovascularization
Ioannis D Ladas, Marilita M Moschos, Thanos D Papakostas, Athanasios I Kotsolis, Ilias Georgalas, Michail ApostolopoulosDepartment of Ophthalmology, “G. Gennimatas” Hospital of Athens, University of Athens, Athens, GreecePurpose: The purpose of this observational case report is to describe a case of skin rash after intravitreal use of bevacizumab.Methods: A 50-year-old man with choroidal neovascularization in the right eye due to age-related macular degeneration was treated with three intravitreal injections of bevacizumab.Results: Twelve days after the first injection, the patient developed a maculopapular rash on his forehead and on both temporal regions around his eyes. The rash disappeared eight days after treatment with topical corticosteroids. A skin rash with the same distribution reappeared 14 days after the second and 10 days after the third injection. Similarly, it disappeared five and seven days after the use of the same treatment. The follow-up period was 15 months after the third injection. During the follow-up period the rash did not reappear.Conclusion: This case report may initiate further investigation of similar cases to support this observation, as there are a lack of reports of skin rash after intravitreal administration of bevacizumab.Keywords: skin rash, bevacizumab, age-related macular degeneratio
Corneal Neovascularization with Associated Lipid Keratopathy in a Patient with Obstructive Sleep Apnea-Hypopnea Syndrome Using a Continuous Positive Airway Pressure Machine.
To report a case of corneal neovascularization with secondary lipid keratopathy in a patient treated with continuous positive airway pressure (CPAP) for obstructive sleep apnea-hypopnea syndrome (OSAHS).
A 49-year-old male had been diagnosed with obstructive sleep apnea syndrome 10 years ago and has been treated with the application of a CPAP machine during night sleep ever since. For the past year, the patient had been complaining for ocular irritation and excessive tearing of the left eye on awakening. Slit-lamp biomicroscopy revealed the presence of neovascularization and lipid exudation in the inferior third of the cornea of the left eye. Ocular patching during night sleep resulted in recession of the reported symptoms and shrinkage of the neovascularization, while the area of lipid exudation ceased to enlarge.
To the best of our knowledge, this is the first report of corneal neovascularization in a patient using a CPAP machine for OSAHS
Transport Northbound Interface:The need for Specification and Standards coordination
Next generation optical transport networks have high benchmarks for flexibility, reliability, and operational simplicity. These requirements underline a common, technology-independent orchestration paradigm that can be extended to represent and configure specific optical technology attributes. Although, orchestration is an ongoing aspect of the current optical transport network evolution, the meaning and scope of orchestration is often only implied, and various Specification and Standards communities cannot always agree the requirements and objectives. This paper describes the high-level requirements facing optical transport networks to provide well-defined Transport Northbound Interface (T-NBI) for optical resource programmability, control, and management automation. It explores the overall functionality that must be provided, whether encompassed in a single large-scale orchestration wrapper or partitioned into several sub-functions, of which only one component is designated as a transport orchestrator. It highlights the early efforts for optical transport resource modeling across Specification and Standardisation organisations. The paper will report on recent Internet Engineering Task Force (IETF) Transport NBI Team Design Team efforts to collaborate across Standards Development Organisations (SDOs) to unify transport interface requirements and objectives. Finally, the paper will highlight use cases and applicability examples, and outline research gaps and challenges, opportunities for researchers, and areas for further collaboration between academia and industry
On the Stability of the Classical Vacua in a Minimal SU(5) 5-D Supergravity Model
We consider a five-dimensional supergravity model with SU(5) gauge symmetry
and the minimal field content. Studying the arising scalar potential we find
that the gauging of the symmetry of the five-dimensional supergravity
causes instabilities. Lifting the instabilities the vacua are of Anti-de-Sitter
type and SU(5) is broken along with supersymmetry. Keeping the
ungauged the potential has flat directions along which supersymmetry is
unbroken.Comment: 24 pages, 2 figure
Keratoconus Treatment Algorithm.
Keratoconus management has significantly changed over the last two decades. The advent of new interventions such as cornea cross-linking, intrastromal corneal ring segments, and combined treatments provide corneal clinicians a variety of treatment options for the visual rehabilitation of keratoconus patients. This review summarizes current evidence for these treatments and highlights their place in keratoconus management while new promising emerging therapies are being investigated
Keratoconus Treatment Algorithm.
Keratoconus management has significantly changed over the last two decades. The advent of new interventions such as cornea cross-linking, intrastromal corneal ring segments, and combined treatments provide corneal clinicians a variety of treatment options for the visual rehabilitation of keratoconus patients. This review summarizes current evidence for these treatments and highlights their place in keratoconus management while new promising emerging therapies are being investigated
Endoscopic-assisted transorbital surgery: Where do we stand on the scott’s parabola? personal considerations after a 10-year experience
Transorbital approaches are genuinely versatile surgical routes which show interesting potentials in skull base surgery. Given their "new" trajectory, they can be a very useful adjunct to traditional routes, even being a valid alternative to them in some cases, and add valuable opportunities in selected patients. Indications are constantly expanding, and currently include selected intraorbital, skull base and even intra-axial lesions, both benign and malignant. Given their relatively recent development and thus unfamiliarity among the skull base community, achieving adequate proficiency needs not only a personalized training and knowledge but also, above all, an adequate case volume and a dedicated setting. Current, but mostly future, applications should be selected by genetic, omics and biological features and applied in the context of a truly multidisciplinary environment
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