1,299 research outputs found
Pathogenesis, presentation, and treatment of keratoconus within the United States
Thesis (M.A.)--Boston UniversityKeratoconus is a non-inflammatory thinning of the cornea that can lead to an irregular conical shaped protrusion generally of the lower mid-peripheral nasal or temporal hemisphere of the cornea. This degenerative disorder has no known individual cause, nor does it have a known cure. Causes have been theorized to be multifactorial ranging from genetic disorders to environmental stimuli. Overall roughly 1 in 2,000 people suffer from the disorder.
The treatment for keratoconus has generally focused on a broad range of different types of contact lenses, with the patients whose corneas degrade to dangerously thin limits or where visual acuity can no longer be corrected, become candidates for corneal transplant surgery. It is today the third most common cause for corneal transplant.
This study focused on detailing the various treatment options keratoconus patients have, as well as what advances these treatments have each made in recent years. These treatments generally focus on maximizing visual acuity while attempting to retain the corneal protrusion. The other goal of these treatments is to push off the necessity for corneal transplant due to the risks of graft rejection, the risks of surgery, and the overall decrease in quality of life an implant can have on a patient’s life. The studies showed that treatment has come a long way, though there still remains to be a treatment that can appropriately halt the progression of keratoconus. This brings the paper to examine the role and potential impact corneal collage cross linking could have on keratoconus patients in the U.S.
Corneal Collagen Cross Linking is a procedure where through riboflavin (vitamin B2) and UV-A light, collagen cross links can be induced within the corneal stroma. By linking the collagen polymers, it is theorized that this could permanently halt the progression of keratoconus. This treatment has been approved in Europe since 2006 and in Canada since 2008, but only entered into clinical trials within the U.S. in 2008.
By performing an extensive literature review, it was concluded that corneal cross linking is a safe and effective method of treatment for keratoconus. Enough literature has been published by the international community over the past 15 years that the U.S. could have begun and concluded FDA clinical trials
sooner. The treatment has the potential to halt the progression of keratoconus before it has any debilitating effects, though as of now is not available to most Americans. With the FDA likely to approve the procedure within the next year, keratoconus patients will have a new treatment option that will very likely substantially improve their quality of life
Are there spurious temperature trends in the United States Climate Division database
The United States (U.S.) Climate Division data set is commonly used in applied climatic studies in the United States. The divisional averages are calculated by including all available stations within a division at any given time. The averages are therefore vulnerable to shifts in average station location or elevation over time, which may introduce spurious trends within these data. This paper examines temperature trends within the 15 climate divisions of New England, comparing the NCDC\u27s U.S. Divisional Data to the U.S. Historical Climate Network (USHCN) data. Correlation and multiple regression revealed that shifts in latitude, longitude, and elevation have affected the quality of the NCDC divisional data with respect to the USHCN. As a result, there may be issues with regard to their use in decadal- to century-scale climate change studies
Controls on dissolved organic carbon quantity and chemical character in temperate rivers of North America
Understanding the processes controlling the transfer and chemical composition of dissolved organic carbon (DOC) in freshwater systems is crucial to understanding the carbon cycle and the effects of DOC on water quality. Previous studies have identified watershed‐scale controls on bulk DOC flux and concentration among small basins but fewer studies have explored controls among large basins or simultaneously considered the chemical composition of DOC. Because the chemical character of DOC drives riverine biogeochemical processes such as metabolism and photodegradation, accounting for chemical character in watershed‐scale studies will improve the way bulk DOC variability in rivers is interpreted. We analyzed DOC quantity and chemical character near the mouths of 17 large North American rivers, primarily between 2008 and 2010, and identified watershed characteristics that controlled variability. We quantified DOC chemical character using both specific ultraviolet absorbance at 254 nm (SUVA254) and XAD‐resin fractionation. Mean DOC concentration ranged from 2.1 to 47 mg C L−1 and mean SUVA254 ranged from 1.3 to 4.7 L mg C−1 m−1. We found a significant positive correlation between basin wetland cover and both bulk DOC concentration (R2 = 0.78; p \u3c 0.0001) and SUVA254 (R2 = 0.91; p \u3c 0.0001), while other land use characteristics were not correlated. The strong wetland relationship with bulk DOC concentration is similar to that found by others in small headwater catchments. However, two watersheds with extremely long surface water residence times, the Colorado and St. Lawrence, diverged from this wetland relationship. These results suggest that the role of riverine processes in altering the terrestrial DOC signal at the annual scale was minimal except in river systems with long surface water residence times. However, synoptic DOC sampling of both quantity and character throughout river networks will be needed to more rigorously test this finding. The inclusion of DOC chemical character will be vital to achieving a more complete understanding of bulk DOC dynamics in large river systems
Genome sequence of an alphaherpesvirus from a beluga whale (Delphinapterus leucas)
Beluga whale alphaherpesvirus 1 was isolated from a blowhole swab taken from a juvenile beluga whale. The genome is 144,144 bp in size and contains 86 putative genes. The virus groups phylogenetically with members of the genus Varicellovirus in subfamily Alphaherpesvirinae and is the first alphaherpesvirus sequenced from a marine mammal
BYOE: Making Connections between Fluid Mechanics and Abstract Painting
This bring your own experiment (BYOE) paper details two iterations of a hands-on painting project that has been well-received by fluid mechanics students. In the conception of this project the authors have explored many of the relevant parameters for different painting techniques: drip painting, pendulum painting spray painting, and acrylic pours – one subset of which is spinning pours. These methods were explored both in terms of relevant fluid mechanic phenomenon as well as with hands-on experimentation, reviewing instructional videos and talking with artists. These efforts led to creation of short instructional videos that students can watch before undertaking their own attempts at creating a work of art. To date this project has been conducted as an extra credit opportunity, though discussion is presented on how the general idea could be deployed as a more traditional experimental lab or as a fun, yet relevant, end of semester lab activity. While the act of creating the fluid art inherently involves learning outcomes related to the importance of thinking creatively, exploring curiosity, prototyping and creating a product with limited project constraints, the instructor can determine the rigor of learning outcomes related to fluid mechanic principles with an accompanying written assignment. This BYOE paper is written with the goal of making the implementation of this project, or some variation of it, straightforward for instructors. Keeping material costs low was part of this consideration and set-up descriptions are provided as well as parts lists
Any Port in a Storm: Vessel Activity and the Risk of IUU-Caught Fish Passing through the World’s Most Important Fishing Ports
This study assesses the risk of fish from illegal, unregulated and unreported (IUU) sources passing through the world’s most important fishing ports and explores the drivers of this risk.
Like previous studies it has attempted to rank ports and States based on landings and vessel visits reported by governments by using Automatic Identification System (AIS) positional data transmitted by fishing and fish carrier vessels to identify the locations of ports and rank them based on the frequency of visits by foreign-flagged and domestic-flagged vessels. It advances our thinking in that (i) the analysis includes an estimation of the hold capacity of fishing vessels and is therefore able to rank ports based on the total hold capacity of vessels visiting them and (ii) the profile and the frequency of vessel visits inform an assessment of the relative risks between different ports, and the implications for the implementation of the Port State Measures Agreement (PSMA). The study also assesses the accuracy and utility of AIS-derived data for determining IUU risk globally for all ports, notably by cross-referencing its findings with those of other studies.
The study develops a broad suite of indicators that quantify and aggregate the AIS-derived port visit information in conjunction with published and publicly available policy and regulatory information drawn from other sources, such as the compliance record with binding port State measures of regional fisheries management organizations, to raise a global port State IUU Risk Index. The comparison of achieved risk scores with national income, levels of corruption, and geography provides insights into factors driving (aggravating) or modulating (mitigating) risks of IUU-caught seafood passing through a Nation’s fishing ports, and supports a view that States with weaker governance also face higher odds of visits by vessels likely to have engaged in IUU fishing (i.e. higher external risks).
Based on an in-depth assessment of 14 individual ports globally, appended as a supplement to this paper, the study finds that overall, and with the possible exception of mandatory advance request procedures for entering ports, the implementation of key provisions of the 2009 PSMA remains severely lacking. The two main areas for improvement are the posting of publicly available PSM-related information on national and/or FAO portals, and the formal designation of ports
Violation of Bells inequality using continuous variable measurements
A Bell inequality is a fundamental test to rule out local hidden variable
model descriptions of correlations between two physically separated systems.
There have been a number of experiments in which a Bell inequality has been
violated using discrete-variable systems. We demonstrate a violation of Bells
inequality using continuous variable quadrature measurements. By creating a
four-mode entangled state with homodyne detection, we recorded a clear
violation with a Bell value of . This opens new
possibilities for using continuous variable states for device independent
quantum protocols.Comment: 5 pages, 4 figures, lette
Chronicle of a Death Foretold: The Green Party of Aotearoa New Zealand and the 2017 General Election
No abstrac
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