Improving Fingerprint-Based Positioning by Using IEEE 802.11mc FTM/RTT Observables.

Received signal strength (RSS) has been one of the most used observables for location purposes due to its availability at almost every wireless device. However, the volatile nature of RSS tends to yield to non-reliable location solutions. IEEE 802.11mc enabled the use of the round trip time (RTT) for positioning, which is expected to be a more consistent observable for location purposes. This approach has been gaining support from several companies such as Google, which introduced that feature in the Android O.S. As a result, RTT estimation is now available in several recent off-the-shelf devices, opening a wide range of new approaches for computing location. However, RTT has been traditionally addressed to multilateration solutions. Few works exist that assess the feasibility of the RTT as an accurate feature in positioning methods based on classification algorithms. An attempt is made in this paper to fill this gap by investigating the performance of several classification models in terms of accuracy and positioning errors. The performance is assessed using different AP layouts, distinct AP vendors, and different frequency bands. The accuracy and precision of the RTT-based position estimation is always better than the one obtained with RSS in all the studied scenarios, and especially when few APs are available. In addition, all the considered ML algorithms perform pretty well. As a result, it is not necessary to use more complex solutions (e.g., SVM) when simpler ones (e.g., nearest neighbor classifiers) achieve similar results both in terms of accuracy and location error.

Prospective, multicenter demographic and epidemiological study on vernal keratoconjunctivitis: a glimpse of ocular surface in Italian population.

PURPOSE: To evaluate the frequency and epidemiological features of vernal keratoconjunctivitis (VKC) in Italy. METHODS: a specific electronic clinical chart for vernal keratoconjunctivitis was created to standardize: 1) medical history; 2) diagnostic criteria; 3) signs and symptoms; and 4) treatments. This study involved 6 Italian referral centers for ocular surface diseases: between March 2005 and March 2006, all referred patients were included, clinical data collected and statistically examined. RESULTS: The mean age of the vernal keratoconjunctivitis population (n = 156) was 13.8 +/- 8.8 with 64.1% of subjects under 14 years of age and a male/female ratio of 3.5:1. Among VKC patients, 48.7% showed associated systemic allergic diseases. Only 32.1% of patients were positive for RAST and/or prick test. The limbal form (53.8%) was the most frequent subtype of vernal keratoconjunctivitis. Approximately 9% of patients showed a severe form of vernal keratoconjunctivitis. At the first visit patients were treated with: multiple action or mast cell stabilizer eye drops (58.1% and 41.3% of cases, respectively), topical corticosteroids alone (0.6%) or in association (26.8% of cases). All patients used topical steroids at least once in the studied year. Systemic antihistamine therapy was used by 25.6% of patients. In this cohort, 32.7% of patients required two or more examinations per year for exacerbations of their symptoms. CONCLUSION: Vernal keratoconjunctivitis is a severe ocular condition that mainly affects young males. Vernal keratoconjunctivitis is characterized by different clinical features and therapeutic responses, suggesting the need for a standardized therapeutic approach on the basis of a grading of disease severity.

A conjunctival mass in the deep superior fornix after a long retained hard contact lens in a patient with keloids.

PURPOSE: To report a case of an upper eyelid mass induced by a rigid contact lens retained for more than 3 years in the eye of a patient with a general history of keloids and to provide a review of the literature on retained contact lenses. METHODS: Case report. RESULTS: A 45-year-old woman with an ophthalmologic history of dry eyes and follicular chronic conjunctivitis presented at our department complaining of irritation, mucous discharge, and contact lens intolerance in her left eye. The ophthalmic examination revealed a visual acuity of 20/20 in both eyes and bilateral blepharitis. A pseudoptosis and an impressive mass growing from the superior tarsal conjunctiva with a lot of mucous discharge were present in the left eye. After a delay of 3.5 years with persisting complaints, a double lid eversion revealed the presence of a hard contact lens retained in the deep fornix of the left eye. After removing the lens and a short period of treatment with local corticosteroids, the mass and the symptoms disappeared. CONCLUSIONS: In patients who wear or wore contact lenses and present with one-sided chronic irritation and tissue proliferation, the possibility of a retained contact lens should be considered. The previous history of dry eyes and chronic conjunctivitis led us to miss the diagnosis at the first visits, despite persisting complaints. No other cases about the effects of a retained contact lens in a patient with keloids have been previously reported.

Autoimmune uveitis in children: clinical correlation between antinuclear antibody positivity and ocular recurrences.

OBJECTIVE: The aim of this study was to identify the correlation between antinuclear antibody (ANA) titre and the onset and clinical course of uveitis in children with juvenile idiopathic arthritis (JIA) or without any other systemic autoimmune disease, i.e., idiopathic uveitis (IU). METHODS: Twenty-two patients affected by uveitis were examined. Ten had JIA-associated uveitis, 12 had IU. Follow-up ranged from 7 to 101 months. The ANA were titrated three times per year and additionally in case of ocular recurrences. All patients were treated with immunosuppressive drug combination therapy (IDCT). RESULTS: JIA-associated uveitis: ocular recurrences were noted in three ANA-positive patients and in one ANA-negative patient. IU uveitis: ocular recurrences were noted in one ANA-positive and in one ANA-negative patient. No significant rise in ANA titre was noted in either group during uveitis recurrence. CONCLUSIONS: (1) ANA had no value in predicting the recurrence of uveitis. (2) IDCT does not influence ANA production.