On a Class of Geodesically Connected Lorentzian Manifolds

AbstractIn this paper we study the geodesical connectedness of Lorentzian manifolds. We consider a connected manifold M=M0×R, where M0is a complete Riemannian manifold endowed with a Lorentzian metricgof splitting type. We prove that, under suitable hypotheses on the coefficients of the metricg,Mis geodesically connected

Correlation between morphological characteristics of macular edema and visual acuity in young patients with idiopathic intermediate uveitis

Background and Objectives: Macular edema (ME) is a common complication of intermediate uveitis (IU). It is often responsible for a decrease in visual acuity (VA). Three distinct patterns of macular edema have been described in intermediate uveitis, namely, cystoid macular edema (CME), diffuse macular edema (DME), and serous retinal detachment (SRD). The current study aims to describe the characteristics of macular edema in young patients with idiopathic intermediate uveitis and to correlate its features with VA using spectral domain optical coherence tomography (SD-OCT). Materials and Methods: A total of 27 eyes from 18 patients with idiopathic IU complicated by ME were included in this retrospective study. All patients underwent SD-OCT; data were gathered at the onset of ME. Best-corrected VA (BCVA) was correlated with the morphological features of ME. Results: BCVA was negatively correlated with Ellipsoid Zone (EZ) disruption (p = 0.00021), cystoid pattern (p = 0.00021), central subfield thickness (CST) (p < 0.001), and serous retinal detachment (0.037). Conclusions: In ME secondary to idiopathic IU, VA negatively correlates with Ellipsoid Zone disruption and increases in CST. Moreover, vision is influenced by the presence of cysts in the inner nuclear and outer nuclear layers and by the neuroepithelium detachment

Management of spontaneous crystalline lens luxation in a patient diagnosed with Takayasu's disease

Takayasu's disease is a chronic granulomatous arteriopathy that affects large vessels and their major branches. Nonspecific symptoms characterize the early phase, whereas findings of arterial occlusion and aneurysmal formation become manifest later. Ocular signs typically refer to retinal vascular involvement, as Takayasu arteritis or hypertensive retinopathy. We report a case of a 63-year-old woman suffering from Takayasu arteritis that complained of sudden onset of blurred vision in her left eye due to crystalline lens luxation in the vitreous cavity. The patient's past medical history was unremarkable for trauma, personal or familiar collagenopathies. Prompt surgical management was performed and the patient reached 0 LogMAR seven days after surgery. Our case illustrates the concomitant occurrence, never reported before, of two rare conditions in the same patient, namely, Takayasu arteritis and spontaneous lens dislocation. Further research and future knowledge are needed to explain whether Takayasu arteritis could obliquely injure zonular or fibrillar structures and whether these features may be possibly related

Attouch-Wets convergence and Kuratowski convergence on compact sets

summary:Let $X$ be a locally connected, $b$-compact metric space and $E$ a closed subset of $X$. Let $\Bbb G$ be the space of all continuous real-valued functions defined on some closed subsets of $E$. We prove the equivalence of the ${\tau_{_{a\!w}}}$ and ${\tau^c_{_{\!K}}}$ topologies on $\Bbb G$, where $\tau_{_{a\!w}}$ is the so called {\sl Attouch-Wets\/} topology, defined in terms of uniform convergence of distance functionals, and ${\tau^c_{_{\!K}}}$ is the topology of Kuratowski convergence on compacta

Light rays having extreme points with the same spatial coordinates

AbstractIn this paper we deal with lightlike geodesics in Lorentzian manifolds which are closed with respect to the spatial coordinates. We consider the case where the initial point is fixed or moves on a level of a given time function. The case where the initial point is free is also considered, under a periodicity condition on the metric

On the geodesical connectedness for a class of Semi-Riemannian manifolds

AbstractWe prove a variational principle for geodesics on a semi-Riemannian manifold M of arbitrary index k and possessing k linearly independent Killing vector fields that generate a timelike distribution on M. Using such a principle and a suitable completeness condition for M, we prove some existence and multiplicity results for geodesics joining two fixed points of M

Deep-seated hydrocarbons in the seep “Brecciated Limestones” of the Maiella area (Adriatic foreland basin): Evaporitic sealing and oil re-mobilization effects linked to the drawdown of the Messinian Salinity Crisis

The 13C-depleted “Brecciated Limestones” record a hydrocarbon seep event that occurred between 5.56 and 5.532 Ma in the Maiella area. They unconformably overlie the “Primary Lower Gypsum” and crop out as carbonate buildups and authigenic patches fed by fluid migration pathways filled with flow-mobilized pelites. Tar occurs as solid bitumen shows, corresponding to pore-filling tar in the microfacies, and as a distinctive brown facies, resulting in finely impregnating patterns in thin section. Geochemical rock characterization confirmed that the measured Total Organic Carbon, with values up to 11.07%, mostly consists of migrated hydrocarbons in the carbonate buildups and the authigenic patches, while the flow- mobilized pelites are devoid of oil traces. Bitumen characterization showed an overall homogeneity among the samples, established by their similarities in the tricyclic fraction and their uniform bitumen d13C signals (␣26.3/␣28.66‰ PDB-1). Gas chromatographyemass spectrometry revealed five distinctive markers indicative of an oil that originated and migrated from a carbonate source rock: high C29/C30 hopane ratio; low Ts/Tm ratio; abundant C24 tetracyclic terpane; absence of diasteranes; and occurrence of methylsteranes. Considering the regional source rock setting, the carbonate source rock might pre- sumably be Upper Triassic/Lower Liassic in age. We favor a conceptual model that envisages a step-wise migration of hydrocarbons, which originated from a deep-seated source and migrated through a hydrofractured reservoir (Bolognano Fm.). The Primary Lower Gypsum of the Messinian Salinity Crisis provided an efficient seal until the major evaporative drawdown of the Mediterranean Sea at ~5.55 Ma triggered a renewed hydrocarbons migration, which occurred first with a vigorous gaseous release and then with a seeping oil flow. Oil impregnated the early cemented “Brecciated Limestones” and partly contributed to their precipitation, whereas a self-clogging effect supposedly prevented oil impregnation in correspondence with the feeder channels formed during the first gaseous migration phase