Search for signatures of magnetically-induced alignment in the arrival directions measured by the Pierre Auger Observatory

We present the results of an analysis of data recorded at the Pierre Auger Observatory in which we search for groups of directionally-aligned events (or 'multiplets') which exhibit a correlation between arrival direction and the inverse of the energy. These signatures are expected from sets of events coming from the same source after having been deflected by intervening coherent magnetic fields. The observation of several events from the same source would open the possibility to accurately reconstruct the position of the source and also measure the integral of the component of the magnetic field orthogonal to the trajectory of the cosmic rays. We describe the largest multiplets found and compute the probability that they appeared by chance from an isotropic distribution. We find no statistically significant evidence for the presence of multiplets arising from magnetic deflections in the present data. (C) 2011 Elsevier B.V. All rights reserved.

Changes in Diadenosine Polyphosphates during Alignment-Fit and Orthokeratology Rigid Gas Permeable

Purpose.: To evaluate the levels of dinucleotides diadenosine tetraphosphate (Ap4A) and diadenosine pentaphosphate (Ap5A) in tears of patients wearing rigid gas permeable (RGP) contact lenses on a daily wear basis and of patients wearing reverse-geometry RGP lenses overnight for orthokeratology treatment. Methods.: Twenty-two young volunteers (10 females, 12 males; 23.47 ± 4.49 years) were fitted with an alignment-fit RGP lens (paflufocon B) for a month, and after a 15-day washout period they were fitted with reverse-geometry RGP lenses for corneal reshaping (paflufocon D) for another month. During each period, tears were collected at baseline day 1, 7, 15, and 28. Ap4A and Ap5A were measured by high-pressure liquid chromatography (HPLC). Additionally, corneal staining, break-up time (BUT), Schirmer test, and dryness symptoms were evaluated. Results.: Ap4A concentrations increased significantly from baseline during the whole period of daily wear of RGP lenses (P < 0.001); concentration was also significantly higher than in the orthokeratology group, which remained at baseline levels during the study period except at day 1 (P < 0.001) and day 28 (P = 0.041). While BUT and Schirmer remained unchanged in both groups, discomfort and dryness were significantly increased during alignment-fit RGP daily wear but not during the orthokeratology period. Conclusions.: Daily wear of RGP lenses increased the levels of Ap4A due to mechanical stimulation by blinking of the corneal epithelium, and this is associated with discomfort. Also, orthokeratology did not produce symptoms or signs of ocular dryness, which could be a potential advantage over soft contact lenses in terms of contact lens-induced dryness.

Visual suppression in intermittent exotropia during binocular alignment.

PURPOSE To investigate the cortical mechanisms that prevent diplopia in intermittent exotropia (X(T)) during binocular alignment (orthotropia). METHODS The authors studied 12 X(T) patients aged 5 to 22 years. Seventy-five percent had functional stereo vision with stereoacuity similar to that of 12 age-matched controls (0.2-3.7 min arc). Identical face images were presented to the two eyes for 400 ms. In one eye, the face was presented at the fovea; in the other, offset along the horizontal axis with up to 12° eccentricity. The task was to indicate whether one or two faces were perceived. RESULTS All X(T) patients showed normal diplopia when the nonfoveal face was presented to nasal hemiretina, though with a slightly larger fusional range than age-matched controls. However, 10 of 12 patients never experienced diplopia when the nonfoveal face was presented to temporal hemiretina (i.e., when the stimulus simulated exodeviation). Patients showed considerable variability when the single image was perceived. Some patients suppressed the temporal stimulus regardless of which eye viewed it, whereas others suppressed a particular eye even when it viewed the foveal stimulus. In two patients, the simulated exodeviation might have triggered a shift from normal to anomalous retinal correspondence. CONCLUSIONS Antidiplopic mechanisms in X(T) can be reliably triggered by purely retinal information during orthotropia, but the nature of these mechanisms varies between patients.