Evaluation of three iterative algorithms for phase modulation regarding their application in concentrating light inside biological tissues for laser induced photothermal therapy

Grant No. UIDB/00645/2020The focusing of light through turbid media like biological tissues is strongly hindered by the scattering of light which limits its safe practice and application in medicine. In order to control this phenomenon, we shaped the incident wavefront using three algorithms including a four-element division algorithm, a partitioning algorithm, and simulated annealing to control, iteratively, a spatial light modulator (SLM). We have tested two different convergence criteria to achieve a focal point inside a turbid environment, made up of a mixture of agar and milk, set to mimic a specific depth of human skin, and provide comparison results. A camera and a lens are used to visualize the focal area and give feedback information to the algorithms. A discussion on the use of these algorithms and convergence criteria is presented, being focused on its convergence time and performance. Depending on the algorithm and operational parameters, improvements of 29% to 46% of the irradiance in the region of interest were accomplished.publishersversionpublishe

Identifying the bank lending channel in Brazil through data frequency

Using the different response timings of credit demand and supply, we isolate supply shifts after monetary policy shocks. We show that the bank lending channel exists in Brazil: after an increase (decrease) in the basic interest rate (Selic), banks reduce (increase) the quantity of new loans and raise (lower) interest rates. However, contrary to the empirical literature for the US, we find evidence that large banks react more than smaller ones to monetary policy shocks. Results may have important implications for monetary policy transmission in light of the recent wave of concentration in the Brazilian banking industry

Novel photochromic 2,2´-bithiophene azo dyes

The photochromic behaviour of two series of 2,2’-bithiophene azo dyes in THF solutions was studied. The photochromic properties and colour constancy were strongly dependent on the substitution pattern of the dyes. Under visible irradiation (> 420 nm) while some dyes exhibited a significant change in the colour intensity others exhibited an almost stable absorption. The photokinetic parameters of these systems are described.Fundação para a Ciência e a Tecnologia (FCT

Implantation of intracorneal ring segments in pediatric patients: long-term follow-up

Purpose: To analyze the long-term outcomes of intracorneal ring segments (ICRS) implantation for keratoconus management in pediatric patients. Methods: Retrospective case series review of the long-term (>5 years) outcomes of Intacs® ICRS implantation for keratoconus in pediatric patients (age <18 years old at the time of surgery) between January 2008 and December 2011 at Ophthalmology Department of Hospital de Santo António. Demographic data, follow-up time, preoperative and postoperative uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) in decimal scale, and corneal topography were evaluated. Statistical analysis was done using SPSS for windows (version 24). Significance was set at p<0.0125. Results: Fourteen eyes of 14 patients, with a mean age of 15.36 years (range 10-18 years), were included in this study. All patients had been diagnosed with keratoconus with reported progression in the 6 months prior to surgery. Follow-up time was 6.36±0.97 years. UCVA and BCVA improved after ICRS implantation (p<0.0125). Keratometry (K) minimum (Kmin) and K maximum (Kmax) decreased after surgery (p<0.0125). During follow-up, UCVA, BCVA, Kmin, and Kmax values ranged, showing a tendency to worsen at the end of follow-up. However, statistically significant differences were not observed. Conclusion: ICRS implantation showed good visual and topographic results in pediatric patients. Long-term follow-up suggests that, despite ICRS implantation, there is still progression of keratoconus. To the best of our knowledge, there are no reports regarding the long-term efficacy of ICRS implantation in pediatric patients.info:eu-repo/semantics/publishedVersio