486 research outputs found

    Identifying A Mechanism For An Infiltration Threshold From The Sunflower River, Ms To The Underlying Alluvial Aquifer

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    Long-term groundwater level and stream stage measurements at a USGS coupled groundwater stream-gaging station located on the Sunflower River in Sunflower, MS show an apparent stage-threshold for infiltration to the underlying alluvial aquifer. This site is located near the center of a large regional groundwater cone of depression in the Mississippi River Valley alluvial aquifer. The USGS well (termed well 3 in this study) was thought to be completed in the regional shallow aquifer, though often recording anomalously high water levels relative to other wells in the region. The purpose of this research was to identify the responsible mechanism for the apparent stage-threshold for surface-groundwater communication. Two possible mechanisms were considered: (1) scour of infiltration-limiting fine-grained bottom sediments during high flow-rate events corresponding to higher stage, (2) and lateral infiltration at high stage into more permeable coarse grained sedimentary layers intersecting the stream channel at higher elevation. A channel bed sediment survey was conducted over 100 km of the river at high stream stage. The stream bottom was composed of cohesive, fine-grained sediments, eliminating the first hypothesis as a viable mechanism. Entrainment of bottom sediments at the higher velocities did not expose coarser-grained, higher-conductivity bottom sediments. Cores were taken throughout the west bank of the river near the USGS well (well 3) along vertical and horizontal transects to measure variations in grain size. A more coarse grained layer (higher sand content) was identified at an elevation of 29.2-31.6 m (msl), consistent with the second hypothesis. Two additional monitoring wells (wells 1 and 2) were installed 1 km upstream, 12 m deeper than well 3. Water levels from these wells were generally 7 m lower than in well 3, were more consistent with regional groundwater levels, and shono response to short-term changes in stream stage. Well 3 appears to be screened within a perched aquifer which is in connection with the Sunflower River at high stream stage through coarse-grained layers intersecting the stream channel at the higher elevations. The two deeper monitoring wells are screened within the regional aquifer, with river-recharge limited to gradual drainage from the perched aquifer. The results have important implications for groundwater assessment and management for the Delta region of Mississippi, especially concerning the role that streams play as potential sources or sinks for the Mississippi Valley Alluvial Aquifer

    Hybridization alters the shape of the genotypic fitness landscape, increasing access to novel fitness peaks during adaptive radiation

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    Estimating the complex relationship between fitness and genotype or phenotype (i.e. the adaptive landscape) is one of the central goals of evolutionary biology. However, adaptive walks connecting genotypes to organismal fitness, speciation, and novel ecological niches are still poorly understood and processes for surmounting fitness valleys remain controversial. One outstanding system for addressing these connections is a recent adaptive radiation of ecologically and morphologically novel pupfishes (a generalist, molluscivore, and scale-eater) endemic to San Salvador Island, Bahamas. We leveraged whole-genome sequencing of 139 hybrids from two independent field fitness experiments to identify the genomic basis of fitness, estimate genotypic fitness networks, and measure the accessibility of adaptive walks on the fitness landscape. We identified 132 single nucleotide polymorphisms (SNPs) that were significantly associated with fitness in field enclosures. Six out of the 13 regions most strongly associated with fitness contained differentially expressed genes and fixed SNPs between trophic specialists; one gene (mettl21e) was also misexpressed in lab-reared hybrids, suggesting a potential intrinsic genetic incompatibility. We then constructed genotypic fitness networks from adaptive alleles and show that scale-eating specialists are the most isolated of the three species on these networks. Intriguingly, introgressed and de novo variants reduced fitness landscape ruggedness as compared to standing variation, increasing the accessibility of genotypic fitness paths from generalist to specialists. Our results suggest that adaptive introgression and de novo mutations alter the shape of the fitness landscape, providing key connections in adaptive walks circumventing fitness valleys and triggering the evolution of novelty during adaptive radiation

    Educational and vocational goal disruption in adolescent and young adult cancer survivors

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    ObjectiveCancer in adolescents and young adults (AYAs) can interrupt important developmental milestones. Absence from school and time lost from work, together with the physical impacts of treatment on energy and cognition, can disrupt educational and vocational goals. The purpose of this paper is to report on AYA cancer survivors’ experiences of reintegration into school and/or work and to describe perceived changes in their educational and vocational goals.MethodsAdolescents and young adults recruited from 7 hospitals in Australia, aged 15 to 26 years and â ¤24 months posttreatment, were interviewed using the psychosocial adjustment to illness scale. Responses were analysed to determine the extent of, and explanations for, cancer’s effect on school/work.ResultsFortyâ two AYA cancer survivors (50% female) participated. Compared with their previous vocational functioning, 12 (28.6%) were scored as experiencing mild impairment, 14 (33.3%) moderate impairment, and 3 (7.1%) marked impairment. Adolescents and young adults described difficulties reintegrating to school/work as a result of cognitive impacts such as concentration problems and physical impacts of their treatment, including fatigue. Despite these reported difficulties, the majority indicated that their vocation goals were of equal or greater importance than before diagnosis (26/42; 62%), and most AYAs did not see their performance as compromised (23/42; 55%). Many survivors described a positive shift in life goals and priorities. The theme of goal conflict emerged where AYAs reported compromised abilities to achieve their goals.ConclusionsThe physical and cognitive impacts of treatment can make returning to school/work challenging for AYA cancer survivors. Adolescents and young adults experiencing difficulties may benefit from additional supports to facilitate meaningful engagement with their chosen educational/vocational goals.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142495/1/pon4525_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142495/2/pon4525.pd

    Discovery of AZD3199, an inhaled ultralong acting β2 receptor agonist with rapid onset of action

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    A series of dibasic des-hydroxy β2 receptor agonists has been prepared and evaluated for potential as inhaled ultra-long acting bronchodilators. Determination of activities at the human β-adrenoreceptors demonstrated a series of highly potent and selective β2 receptor agonists that were progressed to further study in a guinea pig histamine-induced bronchoconstriction model. Following further assessment by; onset studies in guinea pig tracheal rings and human bronchial rings contracted with methacholine (guinea pigs) or carbachol (humans), duration of action studies in guinea pigs after intratracheal (i. t.) administration and further selectivity and safety profiling AZD3199 was shown to have an excellent over all profile and was progressed into clinical evaluation as a new ultra-long acting inhaled β2 receptor agonist with rapid onset of action

    Regional and scale-specific effects of land use on amphibian diversity [poster]

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    Background/Question/Methods Habitat loss and degradation influence amphibian distributions and are important drivers of population declines. Our previous research demonstrated that road disturbance, development and wetland area consistently influence amphibian richness across regions of the U.S. Here, we examined the relative importance of these factors in different regions and at multiple spatial scales. Understanding the scales at which habitat disturbance may be affecting amphibian distributions is important for conservation planning. Specifically, we asked: 1) Over what spatial scales do distinct landscape features affect amphibian richness? and 2) Do road types (non-rural and rural) have similar effects on amphibian richness? This is the second year of a collaborative, nationwide project involving 11 U.S. colleges integrated within undergraduate biology curricula. We summarized North American Amphibian Monitoring Program data in 13 Eastern and Central U.S states and used geographic information systems to extract landscape data for 471 survey locations. We developed models to quantify the influence of landscape variables on amphibian species richness and site occupancy across five concentric buffers ranging from 300m to 10,000m. Results/Conclusions Across spatial scales, development, road density and agriculture were the best predictors of amphibian richness and site occupancy by individual species. Across regions, we found that scale did not exert a large influence on how landscape features influenced amphibian richness as effects were largely comparable across buffers. However, development and percent impervious surface had stronger influence on richness at smaller spatial scales. Richness was lower at survey locations with higher densities of non-rural and rural roads, and non-rural road density had a larger negative effect at smaller scales. Within regions, landscape features driving patterns of species richness varied. The scales at which these factors were associated with richness were highly variable within regions, suggesting the scale effects may be region specific. Our project demonstrates that networks of undergraduate students can collaborate to compile and analyze large ecological data sets, while engaging students in authentic and inquiry-based learning in landscape-scale ecology

    Designing an intervention to help people with colorectal adenomas reduce their intake of red and processed meat and increase their levels of physical activity: a qualitative study

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    Background: most cases of colorectal cancer (CRC) arise from adenomatous polyps and malignant potential is greatest in high risk adenomas. There is convincing observational evidence that red and processed meat increase the risk of CRC and that higher levels of physical activity reduce the risk. However, no definitive randomised trial has demonstrated the benefit of behaviour change on reducing polyp recurrence and no consistent advice is currently offered to minimise patient risk. This qualitative study aimed to assess patients' preferences for dietary and physical activity interventions and ensure their appropriate and acceptable delivery to inform a feasibility trial.Methods: patients aged 60-74 included in the National Health Service Bowel Cancer Screening Programme (NHSBCSP) were selected from a patient tracking database. After a positive faecal occult blood test (FOBt), all had been diagnosed with an intermediate or high risk adenoma (I/HRA) at colonoscopy between April 2008 and April 2010. Interested patients and their partners were invited to attend a focus group or interview in July 2010. A topic guide, informed by the objectives of the study, was used. A thematic analysis was conducted in which transcripts were examined to ensure that all occurrences of each theme had been accounted for and compared.Results: two main themes emerged from the focus groups: a) experiences of having polyps and b) changing behaviour. Participants had not associated polyp removal with colorectal cancer and most did not remember being given any information or advice relating to this at the time. Heterogeneity of existing diet and physical activity levels was noted. There was a lack of readiness to change behaviour in many people in the target population.Conclusion: this study has demonstrated the difficulties involved in developing interventions to change dietary and physical activity behaviour in this population. The need to tailor the intervention to individuals, the lack of knowledge about the aetiology of colon cancer and the lack of motivation to change behaviour are critical factors
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