Outcome analysis of intracorneal ring segments for the treatment of keratoconus based on visual, refractive, and aberrometric impairment

PURPOSE: To analyze the outcomes of intracorneal ring segment (ICRS) implantation for the treatment of keratoconus based on preoperative visual impairment. DESIGN: Multicenter, retrospective, nonrandomized study. METHODS: A total of 611 eyes of 361 keratoconic patients were evaluated. Subjects were classified according to their preoperative corrected distance visual acuity (CDVA) into 5 different groups: grade I, CDVA of 0.90 or better; grade II, CDVA equal to or better than 0.60 and worse than 0.90; grade III, CDVA equal to or better than 0.40 and worse than 0.60; grade IV, CDVA equal to or better than 0.20 and worse than 0.40; and grade plus, CDVA worse than 0.20. Success and failure indices were defined based on visual, refractive, corneal topographic, and aberrometric data and evaluated in each group 6 months after ICRS implantation. RESULTS: Significant improvement after the procedure was observed regarding uncorrected distance visual acuity in all grades (P < .05). CDVA significantly decreased in grade I (P < .01) but significantly increased in all other grades (P < .05). A total of 37.9% of patients with preoperative CDVA 0.6 or better gained 1 or more lines of CDVA, whereas 82.8% of patients with preoperative CDVA 0.4 or worse gained 1 or more lines of CDVA (P < .01). Spherical equivalent and keratometry readings showed a significant reduction in all grades (P ≤ .02). Corneal higher-order aberrations did not change after the procedure (P ≥ .05). CONCLUSIONS: Based on preoperative visual impairment, ICRS implantation provides significantly better results in patients with a severe form of the disease. A notable loss of CDVA lines can be expected in patients with a milder form of keratoconus.

Statistical modeling of protein lysate array data

The protein lysate array is an emerging technology for quantifying the protein concentration ratios in multiple biological samples. It is gaining popularity, and has the potential to answer questions about post-translational modifications and protein pathway relationships. Statistical inference for a parametric quantification procedure has been inadequately addressed in the literature, mainly due to two challenges: the increasing dimension of the parameter space and the need to account for dependence in the data. Each chapter of this thesis addresses one of these issues. In Chapter 1, an introduction to the protein lysate array quantification is presented, followed by the motivations and goals for this thesis work. In Chapter 2, we develop a multi-step procedure for the Sigmoidal models, ensuring consistent estimation of the concentration level with full asymptotic efficiency. The results obtained in this chapter justify inferential procedures based on large-sample approximations. Simulation studies and real data analysis are used to illustrate the performance of the proposed method in finite-samples. The multi-step procedure is simpler in both theory and computation than the single-step least squares method that has been used in current practice. In Chapter 3, we introduce a new model to account for the dependence structure of the errors by a nonlinear mixed effects model. We consider a method to approximate the maximum likelihood estimator of all the parameters. Using the simulation studies on various error structures, we show that for data with non-i.i.d. errors the proposed method leads to more accurate estimates and better confidence intervals than the existing single-step least squares method.

Prevalence of refractive errors in students in Northeastern Brazil

To determine the prevalence of refractive errors in the public and private school system in the city of Natal, Northeastern Brazil. Methods: Refractometry was performed on both eyes of 1,024 randomly selected students, enrolled in the 2001 school year and the data were evaluated by the SPSS Data Editor 10.0. Ametropia was divided into: 1- from 0.1 to 0.99 diopter (D); 2- 1.0 to 2.99D; 3- 3.00 to 5.99D and 4- 6D or greater. Astigmatism was regrouped in: I- with-the-rule (axis from 0 to 30 and 150 to 180 degrees), II- against-the-rule (axis between 60 and 120 degrees) and III- oblique (axis between > 30 and < 60 and >120 and <150 degrees). The age groups were categorized as follows, in: 1- 5 to 10 years, 2- 11 to 15 years, 3- 16 to 20 years, 4- over 21 years. Results: Among refractive errors, hyperopia was the most common with 71%, followed by astigmatism (34%) and myopia (13.3%). Of the students with myopia and hyperopia, 48.5% and 34.1% had astigmatism, respectively. With respect to diopters, 58.1% of myopic students were in group 1, and 39% distributed between groups 2 and 3. Hyperopia were mostly found in group 1 (61.7%) as well as astigmatism (70.6%). The association of the astigmatism axes of both eyes showed 92.5% with axis with-the-rule in both eyes, while the percentage for those with axis againstthe- rule was 82.1% and even lower for the oblique axis (50%). Conclusion: The results found differed from those of most international studies, mainly from the Orient, which pointed to myopia as the most common refractive error, and corroborates the national ones, with the majority being hyperopia

Spatial and temporal measurements using polyoxometalate, enzymatic and biofilm layers on a CMOS 0.35 μm 64 X 64-pixel I.S.F.E.T. array sensor

This thesis presents the achievements and scientific work conducted using a previously designed and fabricated 64 x 64-pixel ion camera with the use of a 0.35 μm CMOS technology. We used an array of Ion Sensitive Field Effect Transistors (ISFETs) to monitor and measure chemical and biochemical reactions in real time. The area of our observation was a 4.2 x 4.3 mm silicon chip while the actual ISFET array covered an area of 715.8 x 715.8 μm consisting of 4096 ISFET pixels in total with a 1 μm separation space among them. The ion sensitive layer, the locus where all reactions took place was a silicon nitride layer, the final top layer of the austriamicrosystems 0.35 μm CMOS technology used. Our final measurements presented an average sensitivity of 30 mV/pH. With the addition of extra layers we were able to monitor a 65 mV voltage difference during our experiments with glucose and hexokinase, whereas a difference of 85 mV was detected for a similar glucose reaction mentioned in literature, and a 55 mV voltage difference while performing photosynthesis experiments with a biofilm made from cyanobacteria, whereas a voltage difference of 33.7 mV was detected as presented in literature for a similar cyanobacterial species using voltamemtric methods for detection. To monitor our experiments PXIe-6358 measurement cards were used and measurements were controlled by LabVIEW software. The chip was packaged and encapsulated using a PGA-100 chip carrier and a two-component commercial epoxy. Printed circuit board (PCB) has also been previously designed to provide interface between the chip and the measurement cards.

Using a voxel-based krogh cylinder array to simulate microvascular contrast enhancement

The goal of this study is to better simulate microscopic and voxel-based dynamic contrast enhancement in magnetic resonance imaging. Specifically, errors imposed by the traditional two-compartment model are reduced by introducing a novel Krogh cylinder network. The two-compartment model was developed for macroscopic pharmacokinetic analysis of dynamic contrast enhancement and generalizing it to voxel dimensions, due to the significant decrease in scale, imposes physiologically unrealistic assumptions. In the project, a system of microscopic exchange between plasma and extravascular-extracellular space is built while numerically simulating the local contrast agent flow between and inside image elements. To do this, tissue parameter maps were created, contrast agent was introduced to the tissue via a flow lattice, and various data sets were simulated. The effects of sources, tissue heterogeneity, and the contribution of individual tissue parameters to an image are modeled. Further, the study attempts to demonstrate the effects of a priori flow maps on image contrast, indicating that flow data is as important as permeability data when analyzing tumor contrast enhancement. In addition, the simulations indicate that it may be possible to obtain tumor-type diagnostic information by acquiring both flow and permeability data.

Ocean bottom pressure records from the Cascadia array and short surface gravity waves

The ocean bottom pressure records from eight stations of the Cascadia array are used to investigate the properties of short surface gravity waves with frequencies ranging from 0.2 to 5 Hz. It is found that the pressure spectrum at all sites is a well-defined function of the wind speed U10 and frequency f, with only a minor shift of a few dB from one site to another that can be attributed to variations in bottom properties. This observation can be combined with the theoretical prediction that the ocean bottom pressure spectrum is proportional to the surface gravity wave spectrum E(f) squared, times the overlap integral I(f) which is given by the directional wave spectrum at each frequency. This combination, using E(f) estimated from modeled spectra or parametric spectra, yields an overlap integral I(f) that is a function of the local wave age inline image. This function is maximum for f∕fPM = 8 and decreases by 10 dB for f∕fPM = 2 and f∕fPM = 30. This shape of I(f) can be interpreted as a maximum width of the directional wave spectrum at f∕fPM = 8, possibly equivalent to an isotropic directional spectrum, and a narrower directional distribution toward both the dominant low frequencies and the higher capillary-gravity wave frequencies.

Comparison of Intraocular Pressure before and after Laser In Situ Keratomileusis Refractive Surgery Measured with Perkins Tonometry, Noncontact Tonometry, and Transpalpebral Tonometry

Purpose. To compare the intraocular pressure (IOP) before and after Laser In Situ Keratomileusis (LASIK), measured by Diaton, Perkins, and noncontact air pulse tonometers. Methods. Fifty-seven patients with a mean age of 34.88 were scheduled for myopia LASIK treatment. Spherical equivalent refraction (SER), corneal curvature (K), and central corneal thickness (CCT) and superior corneal thickness (SCT) were obtained before and after LASIK surgery. IOP values before and after surgery were measured using Diaton, Perkins, and noncontact air pulse tonometers. Results. The IOP values before and after LASIK surgery using Perkins tonometer and air tonometers were statistically significant (). However, no significant differences were found () for IOP values measured with Diaton tonometer. CCT decreases significantly after surgery () but no statistical differences were found in SCT (). Correlations between pre- and postsurgery were found for all tonometers used, with and for the air pulse tonometer, and for Perkins, and and for Diaton. Conclusion. Transpalpebral tonometry may be useful for measuring postsurgery IOP after myopic LASIK ablation because this technique is not influenced by the treatment.

The scientific rationale, design and implementation plan for a Biogeochemical-Argo float array

Biogeochemical-Argo is the extension of the Argo array of profiling floats to include floats that are equipped with biogeochemical sensors for pH, oxygen, nitrate, chlorophyll, suspended particles, and downwelling irradiance. Argo is a highly regarded, international program that measures the changing ocean temperature (heat content) and salinity with profiling floats distributed throughout the ocean. Newly developed sensors now allow profiling floats to also observe biogeochemical properties with sufficient accuracy for climate studies. This extension of Argo will enable an observing system that can determine the seasonal to decadal-scale variability in biological productivity, the supply of essential plant nutrients from deep-waters to the sunlit surface layer, ocean acidification, hypoxia, and ocean uptake of CO2. Biogeochemical-Argo will drive a transformative shift in our ability to observe and predict the effects of climate change on ocean metabolism, carbon uptake, and living marine resource management. Presently, vast areas of the open ocean are sampled only once per decade or less, with sampling occurring mainly in summer. Our ability to detect changes in biogeochemical processes that may occur due to the warming and acidification driven by increasing atmospheric CO2, as well as by natural climate variability, is greatly hindered by this undersampling. In close synergy with satellite systems (which are effective at detecting global patterns for a few biogeochemical parameters, but only very close to the sea surface and in the absence of clouds), a global array of biogeochemical sensors would revolutionize our understanding of ocean carbon uptake, productivity, and deoxygenation. The array would reveal the biological, chemical, and physical events that control these processes. Such a system would enable a new generation of global ocean prediction systems in support of carbon cycling, acidification, hypoxia and harmful algal blooms studies, as well as the management of living marine resources. In order to prepare for a global Biogeochemical-Argo array, several prototype profiling float arrays have been developed at the regional scale by various countries and are now operating. Examples include regional arrays in the Southern Ocean (SOCCOM ), the North Atlantic Sub-polar Gyre (remOcean ), the Mediterranean Sea (NAOS ), the Kuroshio region of the North Pacific (INBOX ), and the Indian Ocean (IOBioArgo ). For example, the SOCCOM program is deploying 200 profiling floats with biogeochemical sensors throughout the Southern Ocean, including areas covered seasonally with ice. The resulting data, which are publically available in real time, are being linked with computer models to better understand the role of the Southern Ocean in influencing CO2 uptake, biological productivity, and nutrient supply to distant regions of the world ocean. The success of these regional projects has motivated a planning meeting to discuss the requirements for and applications of a global-scale Biogeochemical-Argo program. The meeting was held 11-13 January 2016 in Villefranche-sur-Mer, France with attendees from eight nations now deploying Argo floats with biogeochemical sensors present to discuss this topic. In preparation, computer simulations and a variety of analyses were conducted to assess the resources required for the transition to a global-scale array. Based on these analyses and simulations, it was concluded that an array of about 1000 biogeochemical profiling floats would provide the needed resolution to greatly improve our understanding of biogeochemical processes and to enable significant improvement in ecosystem models. With an endurance of four years for a Biogeochemical-Argo float, this system would require the procurement and deployment of 250 new floats per year to maintain a 1000 float array. The lifetime cost for a Biogeochemical-Argo float, including capital expense, calibration, data management, and data transmission, is about $100,000. A global Biogeochemical-Argo system would thus cost about $25,000,000 annually. In the present Argo paradigm, the US provides half of the profiling floats in the array, while the EU, Austral/Asia, and Canada share most the remaining half. If this approach is adopted, the US cost for the Biogeochemical-Argo system would be ~$12,500,000 annually and ~$6,250,000 each for the EU, and Austral/Asia and Canada. This includes no direct costs for ship time and presumes that float deployments can be carried out from future research cruises of opportunity, including, for example, the international GO-SHIP program (http://www.go-ship.org). The full-scale implementation of a global Biogeochemical-Argo system with 1000 floats is feasible within a decade. The successful, ongoing pilot projects have provided the foundation and start for such a system.

Optimization of Energy Distribution in Solar Panel Array Configurations by Graph Theory and Minkowski’s Paths

Nowadays, the development of the photovoltaic (PV) technology is consolidated as a source of renewable energy. The research in the topic of maximum improvement on the energy efficiency of the PV plants is today a major challenge. The main requirement for this purpose is to know the performance of each of the PV modules that integrate the PV field in real time. In this respect, a PLC communications based Smart Monitoring and Communications Module, which is able to monitor at PV level their operating parameters, has been developed at the University of Malaga. With this device you can check if any of the panels is suffering any type of overriding performance, due to a malfunction or partial shadowing of its surface. Since these fluctuations in electricity production from a single panel affect the overall sum of all panels that conform a string, it is necessary to isolate the problem and modify the routes of energy through alternative paths in case of PV panels array configuration.

Simultaneous determination of carotenoids and tocochromanols from palm hybrid oil by hplc with photodiode array and fluorescence detectors.

2016

Single-Polarization Double Refraction in Plasmonic Crystals: Considerations on Energy Flow

We examined the optical properties of nanolayered metal-dielectric lattices. At subwavelength regimes, the periodic array of metallic nanofilms demonstrates nonlocality-induced double refraction, conventional positive and as well as negative. In particular, we report on energy-flow considerations concerning both refractive behaviors concurrently. Numerical simulations provide transmittance of individual beams in Ag-TiO2 metamaterials under different configurations. In regimes of the effective-medium theory predicting elliptic dispersion, negative refraction may be stronger than the expected positive refraction.

High-sensitivity refractive index sensor based on large-angle tilted fiber grating with carbon nanotube deposition

This paper presents a highly sensitive ambient refractive index (RI) sensor based on 81° tilted fiber grating (81°-TFG) structure UV-inscribed in standard telecom fiber (62.5μm cladding radius) with carbon nanotube (CNT) overlay deposition. The sensing mechanism is based on the ability of CNT to induce change in transmitted optical power and the high sensitivity of 81°-TFG to ambient refractive index. The thin CNT film with high refractive index enhances the cladding modes of the TFG, resulting in the significant interaction between the propagating light and the surrounding medium. Consequently, the surrounding RI change will induce not only the resonant wavelength shift but also the power intensity change of the attenuation band in the transmission spectrum. Result shows that the change in transmitted optical power produces a corresponding linear reduction in intensity with increment in RI values. The sample shows high sensitivities of ∼207.38nm/RIU, ∼241.79nm/RIU at RI range 1.344-1.374 and ∼113.09nm/RIU, ∼144.40nm/RIU at RI range 1.374-1.392 (for X-pol and Y-pol respectively). It also shows power intensity sensitivity of ∼ 65.728dBm/RIU and ∼ 45.898 (for X-pol and Y-pol respectively). The low thermal sensitivity property of the 81°-TFG offers reduction in thermal cross-sensitivity and enhances specificity of the sensor.

Chiroptical spectroscopy of biomolecules using chiral plasmonic nanostructures

This thesis explores the potential of chiral plasmonic nanostructures for the ultrasensitive detection of protein structure. These nanostructures support the generation of fields with enhanced chirality relative to circularly polarised light and are an extremely incisive probe of protein structure. In chapter 4 we introduce a nanopatterned Au film (Templated Plasmonic Substrate, TPS) fabricated using a high through-put injection moulding technique which is a viable alternative to expensive lithographically fabricated nanostructures. The optical and chiroptical properties of TPS nanostructures are found to be highly dependent on the coupling between the electric and magnetic modes of the constituent solid and inverse structures. Significantly, refractive index based measurements of strongly coupled TPSs display a similar sensitivity to protein structure as previous lithographic nanostructures. We subsequently endeavour to improve the sensing properties of TPS nanostructures by developing a high through-put nanoscale chemical functionalisation technique. This process involves a chemical protection/deprotection strategy. The protection step generates a self-assembled monolayer (SAM) of a thermally responsive polymer on the TPS surface which inhibits protein binding. The deprotection step exploits the presence of nanolocalised thermal gradients in the water surrounding the TPS upon irradiation with an 8ns pulsed laser to modify the SAM conformation on surfaces with high net chirality. This allows binding of biomaterial in these regions and subsequently enhances the TPS sensitivity levels. In chapter 6 an alternative method for the detection of protein structure using TPS nanostructures is introduced. This technique relies on mediation of the electric/magnetic coupling in the TPS by the adsorbed protein. This phenomenon is probed through both linear reflectance and nonlinear second harmonic generation (SHG) measurements. Detection of protein structure using this method does not require the presence of fields of enhanced chirality whilst it is also sensitive to a larger array of secondary structure motifs than the measurements in chapters 4 and 5. Finally, a preliminary investigation into the detection of mesoscale biological structure is presented. Sensitivity to the mesoscale helical pitch of insulin amyloid fibrils is displayed through the asymmetry in the circular dichroism (CD) of lithographic gammadions of varying thickness upon adsorption of insulin amyloid fibril spherulites and fragmented fibrils. The proposed model for this sensitivity to the helical pitch relies on the vertical height of the nanostructures relative to this structural property as well as the binding orientation of the fibrils.

Real-time anomaly detection of gamma-ray bursts for the Cherenkov Telescope Array using deep learning

The Cherenkov Telescope Array (CTA) will be the next-generation ground-based observatory to study the universe in the very-high-energy domain. The observatory will rely on a Science Alert Generation (SAG) system to analyze the real-time data from the telescopes and generate science alerts. The SAG system will play a crucial role in the search and follow-up of transients from external alerts, enabling multi-wavelength and multi-messenger collaborations. It will maximize the potential for the detection of the rarest phenomena, such as gamma-ray bursts (GRBs), which are the science case for this study. This study presents an anomaly detection method based on deep learning for detecting gamma-ray burst events in real-time. The performance of the proposed method is evaluated and compared against the Li&Ma standard technique in two use cases of serendipitous discoveries and follow-up observations, using short exposure times. The method shows promising results in detecting GRBs and is flexible enough to allow real-time search for transient events on multiple time scales. The method does not assume background nor source models and doe not require a minimum number of photon counts to perform analysis, making it well-suited for real-time analysis. Future improvements involve further tests, relaxing some of the assumptions made in this study as well as post-trials correction of the detection significance. Moreover, the ability to detect other transient classes in different scenarios must be investigated for completeness. The system can be integrated within the SAG system of CTA and deployed on the onsite computing clusters. This would provide valuable insights into the method's performance in a real-world setting and be another valuable tool for discovering new transient events in real-time. Overall, this study makes a significant contribution to the field of astrophysics by demonstrating the effectiveness of deep learning-based anomaly detection techniques for real-time source detection in gamma-ray astronomy.