Reliability of retinal vessel calibre measurements using a retinal oximeter

Background: Summarised retinal vessel diameters are linked to systemic vascular pathology. Monochromatic images provide best contrast to measure vessel calibres. However, when obtaining images with a dual wavelength oximeter the red-free image can be extracted as the green channel information only which in turn will reduce the number of photographs taken at a given time. This will reduce patient exposure to the camera flash and could provide sufficient quality images to reliably measure vessel calibres. Methods: We obtained retinal images of one eye of 45 healthy participants. Central retinal arteriolar and central retinal venular equivalents (CRAE and CRVE, respectively) were measured using semi-automated software from two monochromatic images: one taken with a red-free filter and one extracted from the green channel of a dual wavelength oximetry image. Results: Participants were aged between 21 and 62 years, all were normotensive (SBP: 115 (12) mmHg; DBP: 72 (10) mmHg) and had normal intra-ocular pressures (12 (3) mmHg). Bland-Altman analysis revealed good agreement of CRAE and CRVE as obtained from both images (mean bias CRAE = 0.88; CRVE = 2.82). Conclusions: Summarised retinal vessel calibre measurements obtained from oximetry images are in good agreement to those obtained using red-free photographs.

Large-scale complex IT systems

Society depends on complex IT systems created by integrating and orchestrating independently managed systems. The incredible increase in scale and complexity in them over the past decade means new software-engineering techniques are needed to help us cope with their inherent complexity. The key characteristic of these systems is that they are assembled from other systems that are independently controlled and managed. While there is increasing awareness in the software engineering community of related issues, the most relevant background work comes from systems engineering. The interacting algos that led to the Flash Crash represent an example of a coalition of systems, serving the purposes of their owners and cooperating only because they have to. The owners of the individual systems were competing finance companies that were often mutually hostile. Each system jealously guarded its own information and could change without consulting any other system.

Experimental investigation of the fuel properties of glidfuel, palm oil mill effluent biodiesel and blends

Biofuels derived from industry waste have potential to substitute fossil fuels (Diesel and Gasoline) in internal combustion (IC) engines. Use of waste streams as fuels would help to reduce considerably life-cycle greenhouse gas emissions and minimise waste processing costs. In this study an investigation into the fuel properties of two waste derived biofuels were carried out, they are: (i) Glidfuel (GF) biofuel - a waste stream from paper industry, and (ii) Palm Oil Mill Effluent (POME) biodiesel - biodiesel produced from palm oil industry effluent through various treatment and transesterification process. GF and POME was mixed together at various proportions and separately with fossil diesel (FD) to assess the miscibility and various physical and chemical properties of the blends. Fuel properties such as kinematic viscosity, higher heating value, water content, acid number, density, flash point temperature, CHNO content, sulphur content, ash content, oxidation stability, cetane number and copper corrosion ratings of all the fuels were measured. The properties of GF, POME and various blends were compared with the corresponding properties of the standard FD. Significance of the fuel properties and their expected effects on combustion and exhaust emission characteristics of the IC engine were discussed. Results showed that most properties of both GF and POME biodiesel were comparable to FD. Both GF and POME were miscible with each other, and also separately with the FD. Flash point temperatures of GF and POME biodiesel were 40.7°C and 158.7°C respectively. The flash point temperature of GF was about 36% lower than corresponding FD. The water content in GF and FD were 0.74 (% wt) and 0.01 (% wt) respectively. Acidity values and corrosion ratings of both GF and POME biodiesel were low compared to corresponding value for FD. The study concluded that optimum GF-POME biofuel blends can substitute fossil diesel use in IC engines.

Improving Storage with Stackable Extensions

Storage is a central part of computing. Driven by exponentially increasing content generation rate and a widening performance gap between memory and secondary storage, researchers are in the perennial quest to push for further innovation. This has resulted in novel ways to "squeeze" more capacity and performance out of current and emerging storage technology. Adding intelligence and leveraging new types of storage devices has opened the door to a whole new class of optimizations to save cost, improve performance, and reduce energy consumption. In this dissertation, we first develop, analyze, and evaluate three storage extensions. Our first extension tracks application access patterns and writes data in the way individual applications most commonly access it to benefit from the sequential throughput of disks. Our second extension uses a lower power flash device as a cache to save energy and turn off the disk during idle periods. Our third extension is designed to leverage the characteristics of both disks and solid state devices by placing data in the most appropriate device to improve performance and save power. In developing these systems, we learned that extending the storage stack is a complex process. Implementing new ideas incurs a prolonged and cumbersome development process and requires developers to have advanced knowledge of the entire system to ensure that extensions accomplish their goal without compromising data recoverability. Futhermore, storage administrators are often reluctant to deploy specific storage extensions without understanding how they interact with other extensions and if the extension ultimately achieves the intended goal. We address these challenges by using a combination of approaches. First, we simplify the storage extension development process with system-level infrastructure that implements core functionality commonly needed for storage extension development. Second, we develop a formal theory to assist administrators deploy storage extensions while guaranteeing that the given high level goals are satisfied. There are, however, some cases for which our theory is inconclusive. For such scenarios we present an experimental methodology that allows administrators to pick an extension that performs best for a given workload. Our evaluation demostrates the benefits of both the infrastructure and the formal theory.

Improving caches in consolidated environments

Memory (cache, DRAM, and disk) is in charge of providing data and instructions to a computer's processor. In order to maximize performance, the speeds of the memory and the processor should be equal. However, using memory that always match the speed of the processor is prohibitively expensive. Computer hardware designers have managed to drastically lower the cost of the system with the use of memory caches by sacrificing some performance. A cache is a small piece of fast memory that stores popular data so it can be accessed faster. Modern computers have evolved into a hierarchy of caches, where a memory level is the cache for a larger and slower memory level immediately below it. Thus, by using caches, manufacturers are able to store terabytes of data at the cost of cheapest memory while achieving speeds close to the speed of the fastest one.^ The most important decision about managing a cache is what data to store in it. Failing to make good decisions can lead to performance overheads and over-provisioning. Surprisingly, caches choose data to store based on policies that have not changed in principle for decades. However, computing paradigms have changed radically leading to two noticeably different trends. First, caches are now consolidated across hundreds to even thousands of processes. And second, caching is being employed at new levels of the storage hierarchy due to the availability of high-performance flash-based persistent media. This brings four problems. First, as the workloads sharing a cache increase, it is more likely that they contain duplicated data. Second, consolidation creates contention for caches, and if not managed carefully, it translates to wasted space and sub-optimal performance. Third, as contented caches are shared by more workloads, administrators need to carefully estimate specific per-workload requirements across the entire memory hierarchy in order to meet per-workload performance goals. And finally, current cache write policies are unable to simultaneously provide performance and consistency guarantees for the new levels of the storage hierarchy.^ We addressed these problems by modeling their impact and by proposing solutions for each of them. First, we measured and modeled the amount of duplication at the buffer cache level and contention in real production systems. Second, we created a unified model of workload cache usage under contention to be used by administrators for provisioning, or by process schedulers to decide what processes to run together. Third, we proposed methods for removing cache duplication and to eliminate wasted space because of contention for space. And finally, we proposed a technique to improve the consistency guarantees of write-back caches while preserving their performance benefits.^

Optimizing storage and memory systems for energy and performance

Electrical energy is an essential resource for the modern world. Unfortunately, its price has almost doubled in the last decade. Furthermore, energy production is also currently one of the primary sources of pollution. These concerns are becoming more important in data-centers. As more computational power is required to serve hundreds of millions of users, bigger data-centers are becoming necessary. This results in higher electrical energy consumption. Of all the energy used in data-centers, including power distribution units, lights, and cooling, computer hardware consumes as much as 80%. Consequently, there is opportunity to make data-centers more energy efficient by designing systems with lower energy footprint. Consuming less energy is critical not only in data-centers. It is also important in mobile devices where battery-based energy is a scarce resource. Reducing the energy consumption of these devices will allow them to last longer and re-charge less frequently. Saving energy in computer systems is a challenging problem. Improving a system's energy efficiency usually comes at the cost of compromises in other areas such as performance or reliability. In the case of secondary storage, for example, spinning-down the disks to save energy can incur high latencies if they are accessed while in this state. The challenge is to be able to increase the energy efficiency while keeping the system as reliable and responsive as before. This thesis tackles the problem of improving energy efficiency in existing systems while reducing the impact on performance. First, we propose a new technique to achieve fine grained energy proportionality in multi-disk systems; Second, we design and implement an energy-efficient cache system using flash memory that increases disk idleness to save energy; Finally, we identify and explore solutions for the page fetch-before-update problem in caching systems that can: (a) control better I/O traffic to secondary storage and (b) provide critical performance improvement for energy efficient systems.

Climate Change and Regions at Risk: A Look at Central America

Climate change has been a security issue for mankind since Homo sapiens first emerged on the planet, driving him to find new and better food, water, shelter, and basic resources for survival and the advancement of civilization. Only recently, however, has the rate of climate change coupled with man’s knowledge of his own role in that change accelerated, perhaps profoundly, changing the security paradigm. If we take a ―decades‖ look at the security issue, we see competition for natural resources giving way to Cold War ideological containment and deterrence, itself giving way to non-state terrorism and extremism. While we continue to defend against these threats, we are faced with even greater security challenges that inextricably tie economic, food and human security together and where the flash points may not provide clearly discernable causes, as they will be intrinsically tied to climate change. Several scientific reports have revealed that the modest development gains that can be realized by some regions could be reversed by climate change. This means that climate change is not just a long-term environmental threat as was widely believed, but an economic and developmental disaster that is unfolding. As such, addressing climate change has become central to the development and poverty reduction by the World Bank and other financial institutions. In Latin America, poorer countries and communities, such as those found in Central America, will suffer the hardest because of weaker resilience and greater reliance on climatesensitive sectors such as agriculture. The US should attempt to deliver capability to assist these states to deal with the effects of climate change.

Facebook Forum May 8,2002

Panel discussion held at the College of Business Complex Room 152 at the Modesto Maidique Campus hosted by Florida International University on the subject of Facebook's IPO (initial public offering). FIU experts on the panel included: Bogdan Carbunar, professor in the College of Engineering and Computing Science Rosanna Fiske, associate professor in the School of Journalism and Mass Communication Raul Reis, dean of the School of Journalism and Mass Communication Helen Simon, director of the State Farm Financial Literacy Lab and senior instructor in the College of Business Administration Hannibal Travis, associate professor in the College of Law Patrick O'Leary, Executive Associate Dean for Clinical Affairs at FIU's Herbert Wertheim College of Medicine Moderated by Miami Herald Business Editor Jane Wooldridge

Minicontos: uma prática de letramento emergente na escola

Like numerous other mini ficçion genres, the Flash fiction is configured as a concise and brief genre, but it can still preserve some elements of the traditional tale, such as: narrator, space-temporal unit, characters and plot. For some authors, the emergence of this genre is strictly connected to the speed and diversity of forms of communication in the current social context, that require the reader other skills in addition to reading and writing. Considering the importance of these skills in a literate society and recognizing this genre as potentially effective tool for the development of literacy, this research has as objective to describe the development and implications of didactic sequence directed the literacy practices with the Flash fiction genre. Thus, the research becomes effective in an elementary school vespertine class in 9th grade from Escola Estadual Dr. José Gonçalves de Medeiros, located in the city of Acari-RN. As theoretical assumptions, it will be used fundamentals from Literacy Studies as social practice, especially that ones discussed by the writings Kleiman (1995), Hamilton (2000), Soares (2012), Mortatti (2004) and Rojo (2012). To subsidize the literary literacy, it will be used the theoretical contibutions of Borges (2000), Candido (2004), Pinheiro (2001) and Silva e Silveira (2013). In what relates to the study about the storytellers, it was taken by support the postulates of Gotlib (2006), Bosi (1997), Cortázar (1999), Talbot (2002), Poe (s/d), Luzia de Maria (2004), as well as studies by researchers and writers as Spalding (2007; 2008; 2011), George (2007), Freire (2004) and Trevisan (1994), among others who are dedicated to study Flash fiction. In the methodological field, the proposed perspective anchors itself in an action-researching guidelines (MOREIRA; CALEFFE, 2006) and in the approach of a qualitative data (BOGDAN; BIKLEN, 1994), since it talks to interpretation of diagnosed situation, implementation of intervention actions organized in didactic sequence (SCHNEUWLY; DOLZ, 2004; BARROS; RIVERS-registry, 2014), including description and evaluation of results achieved from the implementation of such actions. The discussions generated indicate that the work with Flash ficition, developed by means of didactic sequences, contributes to the reflection on teaching strategies of Portuguese, used to prepare the students to meet the demands of reading and writing of contemporary society.

Avaliação da aplicabilidade de correlações matemáticas e redes neurais na predição de parâmetros de especificação do diesel

Diesel fuel is one of leading petroleum products marketed in Brazil, and has its quality monitored by specialized laboratories linked to the National Agency of Petroleum, Natural Gas and Biofuels - ANP. The main trial evaluating physicochemical properties of diesel are listed in the resolutions ANP Nº 65 of December 9th, 2011 and Nº 45 of December 20th, 2012 that determine the specification limits for each parameter and methodologies of analysis that should be adopted. However the methods used although quite consolidated, require dedicated equipment with high cost of acquisition and maintenance, as well as technical expertise for completion of these trials. Studies for development of more rapid alternative methods and lower cost have been the focus of many researchers. In this same perspective, this work conducted an assessment of the applicability of existing specialized literature on mathematical equations and artificial neural networks (ANN) for the determination of parameters of specification diesel fuel. 162 samples of diesel with a maximum sulfur content of 50, 500 and 1800 ppm, which were analyzed in a specialized laboratory using ASTM methods recommended by the ANP, with a total of 810 trials were used for this study. Experimental results atmospheric distillation (ASTM D86), and density (ASTM D4052) of diesel samples were used as basic input variables to the equations evaluated. The RNAs were applied to predict the flash point, cetane number and sulfur content (S50, S500, S1800), in which were tested network architectures feed-forward backpropagation and generalized regression varying the parameters of the matrix input in order to determine the set of variables and the best type of network for the prediction of variables of interest. The results obtained by the equations and RNAs were compared with experimental results using the nonparametric Wilcoxon test and Student's t test, at a significance level of 5%, as well as the coefficient of determination and percentage error, an error which was obtained 27, 61% for the flash point using a specific equation. The cetane number was obtained by three equations, and both showed good correlation coefficients, especially equation based on aniline point, with the lowest error of 0,816%. ANNs for predicting the flash point and the index cetane showed quite superior results to those observed with the mathematical equations, respectively, with errors of 2,55% and 0,23%. Among the samples with different sulfur contents, the RNAs were better able to predict the S1800 with error of 1,557%. Generally, networks of the type feedforward proved superior to generalized regression.

(Re)criando (mini)contos de terror: uma experiência de ensino de leitura e escrita de gênero multimodal

Given the multiplicity of languages and media present in contemporary texts, the work with digital genres characterizes itself as essential for teaching, reading and writing. Virtual media is already present in many dayly activities that require the use of language. This shows that the globalized world brings new demands of literacy and various reading practices. Given this perspective, we propose to work the multiliteracies present in the new texts from the enunciative discourse Bakhtinian assumptions. For this, we chose to be as the object of research / intervention, the horror flash fiction multimodal discursive genre, because it is a multissemiótico digital statement of virtual circulation. In this context, this study aimed to understand how the teaching of this kind can contribute to the development of knowledge related to reading and text production, required by multiliteracies, by performing a Didactic Sequence in the classroom, specifically for two classes of elementary school, 7th and 8th grades of public school. The research was based on Bakhtin's theory and the Circle (2009, 2011) on gender perspective in a dialogic and the proposed Dolz and Schneuwly (2004) for the text of teaching through sequences Teaching. We also use the precepts of multiliteracies focused on Rojo (2012, 2013). The methodology used was based on a qualitative approach. We consider the analysis of minicontos produced by students, it's own hibridism of multiliteracies, the discursive characteristics such as composition, style and subject content, in addition to relations dialogicity present in these statements. At the end of the study, we realized that our intervention contributed to the expansion of knowledge of the subjects involved related to reading and multimodal genre production.

Sea-floor images during POLARSTERN cruise ANT-XIII/3 to the Weddell Sea, Antarctica

Transects of a Remotely Operated Vehicle (ROV) providing sea-bed videos and photographs were carried out during POLARSTERN expedition ANT-XIII/3 focussing on the ecology of benthic assemblages on the Antarctic shelf in the South-Eastern Weddell Sea. The ROV-system sprint 103 was equiped with two video- and one still camera, lights, flash-lights, compass, and parallel lasers providing a scale in the images, a tether-management system (TMS), a winch, and the board units. All cameras used the same main lense and could be tilted. Videos were recorded in Betacam-format and (film-)slides were made by decision of the scientific pilot. The latter were mainly made under the aspect to improve the identification of organisms depicted in the videos because the still photographs have a much higher optical resolution than the videos. In the photographs species larger than 3 mm, in the videos larger than 1 cm are recognisable and countable. Under optimum conditions the transects were strait; the speed and direction of the ROV were determined by the drift of the ship in the coastal current, since both, the ship and the ROV were used as a drifting system; the option to operate the vehicle actively was only used to avoide obstacles and to reach at best a distance of only approximately 30 cm to the sea-floor. As a consequence the width of the photographs in the foreground is approximately 50 cm. Deviations from this strategy resulted mainly from difficult ice- and weather conditions but also from high current velocity and local up-welling close to the sea-bed. The sea-bed images provide insights into the general composition of key species, higher systematic groups and ecological guilds. Within interdisciplinary approaches distributions of assemblages can be attributed to environmental conditions such as bathymetry, sediment characteristics, water masses and current regimes. The images also contain valuable information on how benthic species are associated to each other. Along the transects, small- to intermediate-scaled disturbances, e.g. by grounding icebergs were analysed and further impact to the entire benthic system by local succession of recolonisation was studied. This information can be used for models predicting the impact of climate change to benthic life in the Southern Ocean. All these approaches contribute to a better understanding of the fiunctioning of the benthic system and related components of the entire Antarctic marine ecosystem. Despite their scientific value the imaging methods meet concerns about the protection of sensitive Antarctic benthic systems since they are non-invasive and they also provide valuable material for education and outreach purposes.

Sea-floor images from ROV transects during POLARSTERN cruise ANT-XVII/3 (EASIZ III) to the Weddell Sea, Antarctica

Transects of a Remotely Operated Vehicle (ROV) providing sea-bed videos and photographs were carried out during POLARSTERN expedition ANT-XVII/3 focussing on the ecology of benthic assemblages on the Antarctic shelf in the South-Eastern Weddell Sea. The ROV-system sprint 103 was equiped with two video- and one still camera, lights, flash-lights, compass, and parallel lasers providing a scale in the images, a tether-management system (TMS), a winch, and the board units. All cameras used the same main lense and could be tilted. Videos were recorded in Betacam-format and (film-)slides were made by decision of the scientific pilot. The latter were mainly made under the aspect to improve the identification of organisms depicted in the videos because the still photographs have a much higher optical resolution than the videos. In the photographs species larger than 3 mm, in the videos larger than 1 cm are recognisable and countable. Under optimum conditions the transects were strait; the speed and direction of the ROV were determined by the drift of the ship in the coastal current, since both, the ship and the ROV were used as a drifting system; the option to operate the vehicle actively was only used to avoide obstacles and to reach at best a distance of only approximately 30 cm to the sea-floor. As a consequence the width of the photographs in the foreground is approximately 50 cm. Deviations from this strategy resulted mainly from difficult ice- and weather conditions but also from high current velocity and local up-welling close to the sea-bed. The sea-bed images provide insights into the general composition of key species, higher systematic groups and ecological guilds. Within interdisciplinary approaches distributions of assemblages can be attributed to environmental conditions such as bathymetry, sediment characteristics, water masses and current regimes. The images also contain valuable information on how benthic species are associated to each other. Along the transects, small- to intermediate-scaled disturbances, e.g. by grounding icebergs were analysed and further impact to the entire benthic system by local succession of recolonisation was studied. This information can be used for models predicting the impact of climate change to benthic life in the Southern Ocean. All these approaches contribute to a better understanding of the fiunctioning of the benthic system and related components of the entire Antarctic marine ecosystem. Despite their scientific value the imaging methods meet concerns about the protection of sensitive Antarctic benthic systems since they are non-invasive and they also provide valuable material for education and outreach purposes.