The Phytogeographical Significance of Some Rare Plants at Back Bay

The Back Bay region has long been recognized for its many species which reach either their northern or southern limits there. The eminent Harvard botanist M.L. Fernald collected extensively in the Back Bay region during the late 1930\u27s and early 1940\u27s. He postulated the Back Bay area provided a unique opportunity for the migration of fresh and brackish water species through a series of interconnected or neighboring marshes and pools. His collections document the presence of several species which we now consider extirpated. Of especial interest are genera with vicarious species pairs, that is, one area of overlap between wide-ranging species and southern species is at Back Bay. We present information on two such pairs: Lilaeopsis carolinensisand Lilaeopsis chinensis (wide-ranging); and Lippia nodiflora (southern) and Lippia lanceolata (wide-ranging). In addition we discuss species which reach their northern or southern limits at Back Bay. Examples include: Limosella subulata (Scrophulariaceae), a northern species which apparently has been extirpated, and Juncus megacephalus (Juncaceae), an endemic of the southeastern United States which is abundant near its northern limit at Back Bay

I Don\u27t Belong with All the Really Smart Kids Here : Student Characterizations of Belonging in Engineering

This research paper is a qualitative study of how students with diverse demographics, mindsets, and identities describe what it means to belong in engineering. Engineering students’ sense of belonging has a significant impact on students’ decisions to leave engineering. Talented students who feel that they do not belong in engineering are more likely to leave than their peers. Previous studies have focused on belonging for underrepresented students in engineering (e.g., women or minorities) or specific factors contributing to student belonging (e.g., classroom performance). However, few have explored how students describe what it means for them to belong in engineering to understand how this attitude may be formed and internalized by diverse students. To address this gap, thirty-five interviews were conducted with first-year engineering students at four universities under a semi-structured interview protocol to learn about students’ experiences and perceptions of engineering. Interview transcripts were analyzed using inductive and deductive thematic coding to develop broader themes about how a diverse set of undergraduate students describe their sense of belonging in engineering. Student responses were compared to one another while being sensitive to potential differences in students’ demographic or latent diversity (i.e., mindsets, beliefs, and values). Emerging results show differences in how students evaluate belonging relative to their peers. This research can inform and influence engineering faculty to serve students holistically by understanding how students describe belongingness and provides actionable implications to develop and support their sense of belonging. These efforts may support student retention of diverse students across engineering

A taxonomic revision of the genus Hydnora (Hydnoraceae)

Summary: A systematic monograph is presented for Hydnora (Hydnoraceae), a poorly known genus of holoparasitic plants distributed across Africa, Madagascar and southern Arabia. Species of Hydnora are characterised by their underground habit, unusual fleshy flowers and complete absence of leaves or photosynthetic tissue. This is the first detailed monograph of the genus Hydnora since 1935 and is informed by a comprehensive survey of herbarium specimens and literature. Detailed descriptions, full synonymy, distribution maps and discussion concerning confusable taxa are provided for each species, along with notes on ethnobotany, ecology and conservation. We place particular emphasis on the taxonomic value of osmophore geometry and positioning in living and dried material, which are highly consistent within species. We also provide the first detailed assessment of host range across the genus. Hydnora hanningtonii Rendle and H. solmsiana Dinter are reinstated from synonymy, and H. bolinii S.Hatt is newly described here. The infrageneric classification is reviewed and a key is provided for both living and dried material. Species are accompanied by both illustrations and photographs of living and dried material where possible

Morphology Of Striga Forbesii And Preliminary Screening For Resistance In Sorghum

Striga forbesii Benth can be a serious pest problem on sorghum in Southern Africa. Its morphology, as found in the region, was described with the mention of a very small population on the species having an unusual floral form with strongly exerted style and stigma. It thus could be possible that there is some outcrossing in this predominantly autogamous species. The species produces up to 24,654 seeds per plant, and its seed production was compared with that of S. asiatica. Observation nursery screening showed that between 2.0 and 20.0 (%) germplasm accessions, from Zimbabwe, Botswana Swaziland, Lesotho and Angola, have resistance to S. forbesii. In addition, only 6.0 (%) from the Alad nursery and 3.2 (%) from the Karper nursery, which were introduced into the region, showed resistance. Preliminary results from advanced screening trials significant differential reactions to S. forbesii attack among sorghum varieties. Using the modified checkerboard design, five varieties, namely SAR 29, SAR 33, SAR 19, SAR 35 and SAR 37, showed good levels of tolerance of resistance to S. forbesii. The different reactions of susceptibility and resistance or tolerance were discussed relative to the test varieties

Engineering Schottky contacts in open-air fabricated heterojunction solar cells to enable high performance and ohmic charge transport.

The efficiencies of open-air processed Cu2O/Zn(1-x)Mg(x)O heterojunction solar cells are doubled by reducing the effect of the Schottky barrier between Zn(1-x)Mg(x)O and the indium tin oxide (ITO) top contact. By depositing Zn(1-x)Mg(x)O with a long band-tail, charge flows through the Zn(1-x)Mg(x)O/ITO Schottky barrier without rectification by hopping between the sub-bandgap states. High current densities are obtained by controlling the Zn(1-x)Mg(x)O thickness to ensure that the Schottky barrier is spatially removed from the p-n junction, allowing the full built-in potential to form, in addition to taking advantage of the increased electrical conductivity of the Zn(1-x)Mg(x)O films with increasing thickness. This work therefore shows that the Zn(1-x)Mg(x)O window layer sub-bandgap state density and thickness are critical parameters that can be engineered to minimize the effect of Schottky barriers on device performance. More generally, these findings show how to improve the performance of other photovoltaic system reliant on transparent top contacts, e.g., CZTS and CIGS.This work was supported by EPSRC of the UK (award number RG3717)This is the accepted manuscript. The final version is available from ACS at http://pubs.acs.org/doi/abs/10.1021/am5058663

Effects of Snow Water Storage on Hydrologic Partitioning Across the Mountainous, Western United States

In the montane western United States, where the majority of downstream water resources are derived from snowmelt, a warming climate threatens the timing and amount of future water availability. It is expected that the fraction of precipitation falling as snow will continue decreasing and the timing of snowmelt will continue shifting earlier in the year with unknown impacts on partitioning between evapotranspiration and streamflow. To assess this, we employ a Snow Storage Index (SSI) to represent the annual temporal phase difference between daily precipitation and daily modeled surface water inputs (SWI, the sum of rainfall and snowmelt), weighted by the respective amounts. We coupled the SSI metric with a Budyko-based framework to determine the effect of snow water storage on relative hydrologic partitioning across snow-influenced watersheds in the western U.S. Greater snow water storage was positively correlated with greater hydrologic partitioning to streamflow, particularly in the North Cascades/Cascades (r2: 0.62), Blue Mountains (r2: 0.56), Canadian Rockies (r2: 0.55), Idaho Batholith, (r2: 0.48), and Columbia Mountains/Northern Rockies (r2: 0.45). The weekly SWI:P ratio was an equally strong predictor for hydrologic partitioning, particularly in mid-spring (e.g., March/April) in the same mountainous areas (r2: 0.62&ndash;0.74, across the same eco-regions). The retention of snow water storage and subsequent release of stored water in summer months resulted in increased hydrologic partitioning to streamflow. If SSI decreases with future warming, the volume of water partitioned streamflow will decrease non-uniformly across the western U.S. with substantial implications for ecosystems and agricultural, industrial, and domestic water supplies. &nbsp;</p

Laser vision : lidar as a transformative tool to advance critical zone science

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hydrology and Earth System Sciences 19 (2015): 2881-2897, doi:10.5194/hess-19-2881-2015.Observation and quantification of the Earth's surface is undergoing a revolutionary change due to the increased spatial resolution and extent afforded by light detection and ranging (lidar) technology. As a consequence, lidar-derived information has led to fundamental discoveries within the individual disciplines of geomorphology, hydrology, and ecology. These disciplines form the cornerstones of critical zone (CZ) science, where researchers study how interactions among the geosphere, hydrosphere, and biosphere shape and maintain the "zone of life", which extends from the top of unweathered bedrock to the top of the vegetation canopy. Fundamental to CZ science is the development of transdisciplinary theories and tools that transcend disciplines and inform other's work, capture new levels of complexity, and create new intellectual outcomes and spaces. Researchers are just beginning to use lidar data sets to answer synergistic, transdisciplinary questions in CZ science, such as how CZ processes co-evolve over long timescales and interact over shorter timescales to create thresholds, shifts in states and fluxes of water, energy, and carbon. The objective of this review is to elucidate the transformative potential of lidar for CZ science to simultaneously allow for quantification of topographic, vegetative, and hydrological processes. A review of 147 peer-reviewed lidar studies highlights a lack of lidar applications for CZ studies as 38 % of the studies were focused in geomorphology, 18 % in hydrology, 32 % in ecology, and the remaining 12 % had an interdisciplinary focus. A handful of exemplar transdisciplinary studies demonstrate lidar data sets that are well-integrated with other observations can lead to fundamental advances in CZ science, such as identification of feedbacks between hydrological and ecological processes over hillslope scales and the synergistic co-evolution of landscape-scale CZ structure due to interactions amongst carbon, energy, and water cycles. We propose that using lidar to its full potential will require numerous advances, including new and more powerful open-source processing tools, exploiting new lidar acquisition technologies, and improved integration with physically based models and complementary in situ and remote-sensing observations. We provide a 5-year vision that advocates for the expanded use of lidar data sets and highlights subsequent potential to advance the state of CZ science.The workshop forming the impetus for this paper was funded by the National Science Foundation (EAR 1406031). Additional funding for the workshop and planning was provided to S. W. Lyon by the Swedish Foundation for International Cooperation in Research and Higher Education (STINT grant no. 2013-5261). A. A. Harpold was supported by an NSF fellowship (EAR 1144894)

Protective role of vitamin B6 (PLP) against DNA damage in Drosophila models of type 2 diabetes

Growing evidence shows that improper intake of vitamin B6 increases cancer risk and several studies indicate that diabetic patients have a higher risk of developing tumors. We previously demonstrated that in Drosophila the deficiency of Pyridoxal 5' phosphate (PLP), the active form of vitamin B6, causes chromosome aberrations (CABs), one of cancer prerequisites, and increases hemolymph glucose content. Starting from these data we asked if it was possible to provide a link between the aforementioned studies. Thus, we tested the effect of low PLP levels on DNA integrity in diabetic cells. To this aim we generated two Drosophila models of type 2 diabetes, the first by impairing insulin signaling and the second by rearing flies in high sugar diet. We showed that glucose treatment induced CABs in diabetic individuals but not in controls. More interestingly, PLP deficiency caused high frequencies of CABs in both diabetic models demonstrating that hyperglycemia, combined to reduced PLP level, impairs DNA integrity. PLP-depleted diabetic cells accumulated Advanced Glycation End products (AGEs) that largely contribute to CABs as α-lipoic acid, an AGE inhibitor, rescued not only AGEs but also CABs. These data, extrapolated to humans, indicate that low PLP levels, impacting on DNA integrity, may be considered one of the possible links between diabetes and cancer

In-Service Performance of Airport Flexible Pavements Constructed Following State Specifications for Highway Pavement Materials

692M15-19-T-00026The Federal Aviation Administration (FAA) Reauthorization Act of 2018, Section 136 requires the FAA to allow the use of state highway specifications for airfield pavement construction at non-primary airports serving aircraft with a gross weight less than 60,000 lb if requested by the state. To confirm that state highway specifications provide an acceptable level of performance when used on airport pavements, the FAA initiated this project to compare the performance of airports constructed using state highway specifications with those constructed using FAA specifications. Performance data and specifications from 40 airport projects in five states were analyzed, with 21 using FAA specifications and 19 using state highway specifications. Based on the summarized pavement condition index (PCI) ratings from those projects (which are based on visual condition surveys and do not consider structural or functional performance), it was determined that the performance of airport asphalt pavements constructed using state highway specifications is statistically equivalent to asphalt pavements constructed using FAA specifications. The evaluations encompassed performance periods ranging from 1 to 15 years. Performance trends for the statistical analysis conducted showed an approximate PCI rating of 60 at year 14 for pavements constructed with both types of specifications. It was also determined that climate-based distresses were the predominant mode of distress for both FAA and state highway specification projects, with longitudinal and transverse cracking and weathering as the most prevalent types of distresses. The number of distresses that were load related was relatively minor, as only 8 of the 40 projects evaluated had load-related distresses. Of those projects, five used state highway specifications, and three used FAA specifications