Improvement of indoor VLC network downlink scheduling and resource allocation

Indoor visible light communications (VLC) combines illumination and communication by utilizing the high-modulation-speed of LEDs. VLC is anticipated to be complementary to radio frequency communications and an important part of next generation heterogeneous networks. In order to make the maximum use of VLC technology in a networking environment, we need to expand existing research from studies of traditional point-to-point links to encompass scheduling and resource allocation related to multi-user scenarios. This work aims to maximize the downlink throughput of an indoor VLC network, while taking both user fairness and time latency into consideration. Inter-user interference is eliminated by appropriately allocating LEDs to users with the aid of graph theory. A three-term priority factor model is derived and is shown to improve the throughput performance of the network scheduling scheme over those previously reported. Simulations of VLC downlink scheduling have been performed under proportional fairness scheduling principles where our newly formulated priority factor model has been applied. The downlink throughput is improved by 19.6% compared to previous two-term priority models, while achieving similar fairness and latency performance. When the number of users grows larger, the three-term priority model indicates an improvement in Fairness performance compared to two-term priority model scheduling

A Manipulative Experiment to Estimate Biparental Inbreeding in Monkeyflowers

Biparental inbreeding occurs when plants receive pollen from genetically related neighbors. The frequency of biparental inbreeding in natural populations is unknown but directly relevant to the evolution of plant mating systems. We suggest a simple manipulative experiment to distinguish the effects of biparental inbreeding from those of self‐fertilization. The basis of the method is to compare the levels of inbreeding in plants with and without the potential to outcross with genetic relatives. We eliminate the potential for biparental inbreeding by transplanting seedlings to different locations within a population. The level of inbreeding is then estimated from homozygosity at molecular markers. This method is applied in a study of two natural populations of Mimulus guttatus (the yellow monkeyflower) using microsatellites as marker loci. In contrast to previous studies of this species, our study finds no evidence of biparental inbreeding in either population

Corolla Morphology Facilitates Both Autogamy and Bumblebee Pollination in Mimulus guttatus

The showy corolla of Mimulus guttatus is generally considered an adaptation to attract pollinators. We use phenotypic manipulations to demonstrate that corolla morphology plays a critical mechanical role in both outcrossing and self‐fertilization. In the absence of pollinators, the lower portion of the corolla facilitates autogamy by retaining pollen released from the anthers. A substantial portion of self‐fertilization seems to occur late in the floral life span as the stigma contacts the corolla. When pollinators are present, the corolla facilitates outcrossing before, during, and after insect visitation. A large fraction of cross‐pollen is actually captured by the corolla and not by the stigma. This “indirect” pathway for pollen reception suggests that a large fraction of cross‐pollination in M. guttatus actually occurs long after a pollinator departs from a flower

GIS in Indigenous Communities isn't Participatory GIS: Examples in Honduras and Mexico

KU Department of GeographyPlatinum Sponsors Coca-Cola Gold Sponsors KU Department of Geography KU Institute for Policy & Social Research KU Libraries GIS and Data Services State of Kansas Data Access and Support Center (DASC) Wilson & Company Engineers and Architects Silver Sponsors Bartlett & West Kansas Applied Remote Sensing Program KansasView Bronze Sponsors Garmin KU Biodiversity Institut

Monitoring and modeling primary production in coastal waters: studies in Massachusetts Bay 1992-1994

During 1992-1994, we made shipboard incubations suitable for determining rates of primary production in water from Boston Harbor, Massachusetts Bay, and Cape Cod Bay (Massachusetts, USA). These measurements were part of an extensive baseline monitoring program to characterize water quality prior to diversion of effluent from Boston Harbor directly into Massachusetts Bay via a submarine outfall diffuser. Production (P) was measured using whole-water samples exposed to irradiance (I) levels from ~5 to 2000 µE m-2 s-1. P-I incubations were performed on 6 surveys a year, spaced to capture principal features of the annual production cycle. The number of stations and depths examined varied between years. There were 10 stations and 2 depths sampled in 1992-1993. In 1994, we performed in-depth studies at 2 stations (Boston Harbor\u27s edge and western Massachusetts Bay) by sampling 4 depths. Using depth-intensive 1994 data a simple empirical regression model, using information on chlorophyll biomass, incident daily light, and the depth of the photic zone, predicted integrated primary production rates derived from P-I incubations. The regression model was virtually the same as described for other coastal waters, giving confidence in general use of the model as an extrapolation tool. Using the 1994-based empirical model, we obtained favorable comparisons with production rates modeled from 1992-1993 P-I incubations. Combining the regression model with data on chlorophyll, light, and the photic zone collected on frequent hydrographic surveys (up to 16 yr-1), annual primary production was estimated for 1992-1994. Primary production in an intensively studied region of western Massachusetts Bay (21 hydrographic profile stations in an area ~100 km2) ranged from 386 to 468 g C m-2 yr-1. For a station at the edge of Boston Harbor near Deer Island extrapolations suggested production rates of 263 to 546 g C m-2 yr-1. Based on 2 stations in central Cape Cod Bay (1992-1993 only), model extrapolations suggested an annual production of 527 to 613 g C m-2 yr-1. Analyses using incubation and modeling results suggested that production variability was strongly related to fluctuations in incident irradiance, especially at daily to seasonal time scales. Chlorophyll variability secondarily influenced production, especially at seasonal to annual time scales. Finally, we provide a case where equivalent production was achieved in environments with contrasting water quality (nutrient and chlorophyll concentrations) because of variations in the depth of the photic zone (controlled by both chlorophyll and non-chlorophyll turbidity). Comparative analyses showed that our study estimates of primary production were consistent with the literature on nutrient-rich shelf environments. In conclusion, our study validated an empirical modeling approach to determining primary production in coastal marine waters

Population structure and local selection yield high genomic variation in Mimulus guttatus

Across western North America, Mimulus guttatus exists as many local populations adapted to site-specific environmental challenges. Gene flow between locally adapted populations will affect genetic diversity both within demes and across the larger metapopulation. Here, we analyse 34 whole-genome sequences from the intensively studied Iron Mountain population (IM) in conjunction with sequences from 22 Mimulus individuals sampled from across western North America. Three striking features of these data address hypotheses about migration and selection in a locally adapted population. First, we find very high levels of intrapopulation polymorphism (synonymous =0.033). Variation outside of genes is likely even higher but difficult to estimate because excessive divergence reduces the efficiency of read mapping. Second, IM exhibits a significantly positive genomewide average for Tajima\u27s D. This indicates allele frequencies are typically more intermediate than expected from neutrality, opposite the pattern observed in many other species. Third, IM exhibits a distinctive haplotype structure with a genomewide excess of positive associations between rarer alleles at linked loci. This suggests an important effect of gene flow from other Mimulus populations, although a residual effect of population founding might also contribute. The combination of multiple analyses, including a novel tree-based analytic method, illustrates how the balance of local selection, limited dispersal and metapopulation dynamics manifests across the genome. The overall genomic pattern of sequence diversity suggests successful gene flow of divergent immigrant genotypes into IM. However, many loci show patterns indicative of local adaptation, particularly at SNPs associated with chromosomal inversions

Undergraduate financial aid and subsequent giving behavior

Data on 2,822 Vanderbilt University graduates are used to investigate alumni giving behavior during the eight years after graduation. A two stage model accounting for incidental truncation is used to first estimate the likelihood of making a contribution and second estimate the average gift size conditional on contributing. The type of financial aid received as an undergraduate appears to have a greater influence on subsequent alumni generosity than the amount received. Adding some scholarship to a loanonly package or eliminating all loans from a mixed loan-grant package increases the likelihood of a subsequent contribution. Increasing the total size of the package or altering the proportions of an already mixed package appears to be inconsequential for future donations. Students who receive small merit scholarships contribute more as alumni than students who receive either no merit scholarship or a large merit scholarship

A case of deciduoma malignum

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Spatially and temporally varying selection on intra-population QTL for a life history tradeoff in Mimulus guttatus

This is the peer reviewed version of the following article: MOJICA, J. P., LEE, Y. W., WILLIS, J. H. and KELLY, J. K. (2012), Spatially and temporally varying selection on intrapopulation quantitative trait loci for a life history trade-off in Mimulus guttatus. Molecular Ecology, 21: 3718–3728. doi:10.1111/j.1365-294X.2012.05662.x, which has been published in final form at http://doi.org/10.1111/j.1365-294X.2012.05662.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Why do populations remain genetically variable despite strong continuous natural selection? Mutation reconstitutes variation eliminated by selection and genetic drift, but theoretical and experimental studies each suggest that mutation-selection balance insufficient to explain extant genetic variation in most complex traits. The alternative hypothesis of balancing selection, wherein selection maintains genetic variation, is an aggregate of multiple mechanisms (spatial and temporal heterogeneity in selection, frequency-dependent selection, antagonistic pleiotropy, etc.). Most of these mechanisms have been demonstrated for Mendelian traits, but there is little comparable data for loci affecting quantitative characters. Here, we report a three-year field study of selection on intra-population Quantitative Trait Loci (QTL) of flower size, a highly polygenic trait of Mimulus guttatus. The QTL exhibit antagonistic pleiotropy: alleles that increase flower size reduce viability but increase fecundity. The magnitude and direction of selection fluctuates yearly and on a spatial scale of meters. This study provides direct evidence of balancing selection mechanisms on QTL of an ecologically relevant trait

The effects of the filter-feeding clam Mercenaria mercenaria on carbon cycling in experimental marine mesocosms

The metabolism and the fate of 14C labelled carbon was examined in 4 outdoor mesocosm (13 m3) tanks containing both benthic and pelagic compartments. Mesocosms with (16/m2) and without the clam, Mercenaria mercenaria were compared. System production, net and gross sedimentation of particulate carbon and benthic remineralization of dissolved inorganic nitrogen were all greater in mesocosms with clams. A filtration rate model, dependent on clam size and temperature, explained between 74–114% of the increased gross sedimentation in clam tanks relative to controls.The higher production in the clam tanks was at least in part due to a greater flux of dissolved inorganic nitrogen from the benthos. Despite this greater production in the clam tanks, water column biomass remained similar to controls. Calculations based on the filtration rate model indicated that clams could have consumed between 30% and 46% of the excess biomass produced during the day. Loss of particles due to processes in the water column appeared to consume most of this excess biomass. Although clams enhanced production and sedimentation, they did not limit phytoplankton biomass in the water column through filtration