Proton damage comparison of an e2v technologies n-channel and p-channel CCD204

Comparisons have been made of the relative degradation of charge transfer efficiency in n-channel and p-channel CCDs subjected to proton irradiation. The comparison described in this paper was made using e2v technologies plc. CCD204 devices fabricated using the same mask set. The device performance was compared over a range of temperatures using the same experimental arrangement and technique to provide a like-for-like comparison. The parallel transfer using the p-channel CCD was then optimized using a trap pumping technique to identify the optimal operating conditions at 153 K

What image features guide lightness perception?

Lightness constancy is the ability to perceive black and white surface colors under a wide range of lighting conditions. This fundamental visual ability is not well understood, and current theories differ greatly on what image features are important for lightness perception. Here we measured classification images for human observers and four models of lightness perception to determine which image regions influenced lightness judgments. The models were a high-pass-filter model, an oriented difference-of-Gaussians model, an anchoring model, and an atmospheric-link-function model. Human and model observers viewed three variants of the argyle illusion (Adelson, 1993) and judged which of two test patches appeared lighter. Classification images showed that human lightness judgments were based on local, anisotropic stimulus regions that were bounded by regions of uniform lighting. The atmospheric-link-function and anchoring models predicted the lightness illusion perceived by human observers, but the high-pass-filter and oriented-difference-of-Gaussians models did not. Furthermore, all four models produced classification images that were qualitatively different from those of human observers, meaning that the model lightness judgments were guided by different image regions than human lightness judgments. These experiments provide a new test of models of lightness perception, and show that human observers' lightness computations can be highly local, as in low-level models, and nevertheless depend strongly on lighting boundaries, as suggested by midlevel models.York University Librarie

Hydrologic Impacts of Climate and Land Use Changes in the West Fork San Jacinto River of Texas

Changes to climate and land use/land cover (LULC) are expected to be a source of uncertainty to streamflows in the Gulf Coastal Plains of Texas. Additionally, the city of Houston, Texas, is expected to experience spreading urbanization and immense population growth over the coming century, reaching 10 million people by 2050. As population grows over the next century so does the need for water in a city where groundwater is not a viable resource due to land subsidence. The West Fork San Jacinto (WFSJ) River’s watershed is expected to undergo rapid urbanization as Houston continues to sprawl and the water supply reservoir located on the WFSJ River, Lake Conroe, will have an increased importance in the coming century. Within the WFSJ watershed, changes in LULC are highlighted by an increase of urban land cover from 5.39% in 1992 to 14.7% in 2011. With this, impervious cover increased from 3.10% to 4.01% of the total watershed area from 2001 to 2011. The WFSJ River’s historical streamflow was investigated using two stream gauges for the periods of October 1974 to September 2016 and October 1984 to September 2016 for the upstream and downstream stream gauges, respectively. Historical trends for these periods were investigated using the Seasonal-Trend decomposition procedure based on Loess (STL), flow distribution, Richards-Baker Flashiness Index, and flow distribution. STL results showed a significant downward trend in streamflow for 3, 5, and 7 year trends. The only significant trend found was for mean monthly streamflow at both locations. This is possibly an indicator that urbanization had yet to reach a tipping point within the iii watershed for the historical period, but may also indicate that streamflow data was inadequate for trend detection due to gaps in streamflow records. The Variable Infiltration Capacity (VIC) hydrological model was utilized to investigate future scenarios of LULC and climate. A baseline period of 2001 to 2010 was established for climate and LULC and a future period was set for 2080 to 2089. Future climate scenario was based on the Representative Concentration Pathway 8.5 (RCP8.5) and future LULC was based on the USGS LandCarbon A2 scenario. In total, four scenarios were ran using VIC: baseline, LULC change, climate change, and combined LULC and climate change. Under the LULC change scenario streamflows increased by 0.39% and 4.66% for spring and summer, respectively, but decreased by 0.64% and 6.76% for fall and winter, respectively. Under the climate change scenario, streamflows decreased by 38.96%, 56.79%, 76.06%, and 48.44% for winter, spring, summer, and fall, respectively. The combined LULC and climate change scenario also exhibited decreases by 34.75%, 44.31%, 68.90%, and 45.12% for winter, spring, summer, and fall, respectively. Decreases in precipitation and increases to temperatures associated with climate change create an environment that favors lower streamflows but LULC changes have the ability to counteract these decreases. The study highlighted the uncertainty facing the water resources of the WFSJ watershed and Lake Conroe. The results indicate that less water will be available for the growing Houston metropolitan area

Evolution of proton-induced defects in a cryogenically irradiated p-channel CCD

P-channel CCDs have been shown to display improved tolerance to radiation-induced charge transfer inefficiency (CTI) when compared to n-channel CCDs. This is attributed to the properties of the dominant charge-trapping defect species in p-channel silicon relative to the operating conditions of the CCD. However, precise knowledge of defect parameters is required in order to correct for any induced CTI. The method of single trap-pumping allows us to analyse the defect parameters to a degree of accuracy that cannot be achieved with other common defect analysis techniques such as deep-level transient spectroscopy (DLTS). We have analysed using this method the defect distribution in an e2v p-channel CCD204 irradiated with protons at cryogenic temperature (153K). The dominant charge trapping defects at these conditions have been identified as the donor level of the silicon divacancy and the carbon interstitial defect. The defect parameters are analysed both immediately post irradiation and following several subsequent room-temperature anneal phases. The evolution of the defect distribution over time and through each anneal phase provides insight into defect interactions and mobility post-irradiation. The results demonstrate the importance of cryogenic irradiation and annealing studies, with large variations seen in the defect distribution when compared to a device irradiated at room-temperature, which is the current standard procedure for radiation testing

Rapid Diagnosis of Malaria

Malaria's global impact is expansive and includes the extremes of the healthcare system ranging from international travelers returning to nonendemic regions with tertiary referral medical care to residents in hyperendemic regions without access to medical care. Implementation of prompt and accurate diagnosis is needed to curb the expanding global impact of malaria associated with ever-increasing antimalarial drug resistance. Traditionally, malaria is diagnosed using clinical criteria and/or light microscopy even though both strategies are clearly inadequate in many healthcare settings. Hand held immunochromatographic rapid diagnostic tests (RDTs) have been recognized as an ideal alternative method for diagnosing malaria. Numerous malaria RDTs have been developed and are widely available; however, an assortment of issues related to these products have become apparent. This review provides a summary of RDT including effectiveness and strategies to select the ideal RDT in varying healthcare settings

Wikipedia in Court: When and How Citing Wikipedia and Other Consensus Websites Is Appropriate

(Excerpt) Accordingly, this Article lays out a process for determining when it is and when it is not appropriate to cite Wikipedia and other similar online sources. Part II reviews the history of Wikipedia and controversies caused by citing it. Part III offers a proper citation format and proposes a common sense framework to decide when citing Wikipedia is appropriate. Part IV applies this framework in the context of a variety of actual court cases that cited Wikipedia and shows how the same concepts apply to other consensus-based websites like Urban Dictionary

Wikipedia in Court: When and How Citing Wikipedia and Other Consensus Websites Is Appropriate

(Excerpt) Accordingly, this Article lays out a process for determining when it is and when it is not appropriate to cite Wikipedia and other similar online sources. Part II reviews the history of Wikipedia and controversies caused by citing it. Part III offers a proper citation format and proposes a common sense framework to decide when citing Wikipedia is appropriate. Part IV applies this framework in the context of a variety of actual court cases that cited Wikipedia and shows how the same concepts apply to other consensus-based websites like Urban Dictionary

Occurrence, Persistence, and Expansion of Saltcedar (Tamarix Spp.) Populations in the Great Plains of Montana

Saltcedar (Tamarix spp.), a shrub native to Eurasia, is associated with major alterations to wetland and riparian systems in the southwestern United States. Since the 1960s saltcedar has been naturalized in northern states of the U.S. where its growth potential and impacts are not well known. Here, we describe the occurrence, age, size, and relative cover of saltcedar populations in several river basins in central eastern Montana, USA, to identify potential patterns of spread across the region and changes in individual populations as they age. Stands were aged according to the oldest saltcedar individuals and were sampled for dominant plant cover and soil properties. Multiple introductions appear to have occurred in Montana, with the oldest stands occurring on the Bighorn River in southern Montana. Saltcedar absolute and relative cover and stand area increased significantly with stand age, while native tree and shrub relative cover remained low across all stand ages. These results suggest that saltcedar stands establish where woody natives are not abundant and that they persist and expand over time. Although soil salinity remained constant, soil pH decreased with saltcedar stand age, indicating a possible effect of organic matter inputs. An analysis of annual wood increment of saltcedar and sandbar willow (a native with analogous growth form) stems along a latitudinal gradient showed that stern growth of both species did not differ significantly among regions. Stem growth decreased inversely with elevation for both species while growth responses to elevation did not differ between species. Our results show an increase in number of populations and continued viability of these populations. Mechanisms of saltcedar increases in this region are yet to be determined. Anthropogenic influences, such as saltcedar plantings, watershed alterations (e.g., river flow control), and habitat disturbances (e.g., cattle grazing or habitat clearing) may facilitate its spread in similar climates of the Great Plains