Understanding Rare Species In California: An Assessment Of Camatta Canyon Amole (Hooveria Purpurea Var. Reducta) And A Meta-Analysis Of California Rare Plants In Literature

California is currently in the midst of a biodiversity crisis. There are approximately 5,000 native species of plants in California, a quarter of which are considered rare. Determining threats to these rare plants is often times difficult. Despite California\u27s botanical resources, we still know very little about much of California’s rare plants. San Luis Obispo County is home to 2,000 of California’s native plant taxa, one- third of which are rare or endemic to the county. These species are of great local and environmental concern. In Chapter 1, we attempted to assess the impact of non native species on a threatened species in eastern San Luis Obispo County. We conducted an invasive thatch removal experiment on 10 vegetation plots of Camatta Canyon Amole, Hooveria purpurea var. reducta. The Camatta Canyon Amole (CCA) is a federally listed “threatened” plant that is only known to occur on 21.15 ha of land on Los Padres National Forest (LPNF). In the 1980s, U.S. Fish and Wildlife Service established 10 plots to monitor the population of CCA. These biologists recorded a decrease in the CCA since the establishment of those plots in the 1980s. One hypothesis for the decline is the absence of cattle grazing from LPNF, which has resulted in the accumulation of a dense thatch layer. We experimentally removed this thatch layer in five of the 1980s vegetation plots to test this hypothesis. While our the experiment was designed to be a long term treatment, from the first 1.5 years, we found no relationship between thatch removal and the amount of CCA in each plot. The effect of our treatment may take many years to materialize. In Chapter 2, we conducted extensive botanical surveys of the Camatta Ranch, a 32,000 acre cattle ranch in eastern San Luis Obispo County. The goal of these surveys was to estimate the distribution and population size of CCA on private property, which has never before been accessed or surveyed. We did this in two ways: 1) We created a density ratio estimate based off of plot sampling done on the ranch and 2) we created a species distribution model (SDM) to predict the likelihood of presence throughout the ranch. Our surveys of Camatta Ranch, coupled with our SDM suggest that a majority of CCA’s preferred habitat is on Camatta Ranch, making the ranch of paramount concern for CCA’s protection. Our estimates suggest that 90% of the total population of CCA occurs on Camatta Ranch. In Chapter 3, we attempted to quantify biases in the literature about California’s flora. The California Floristic Province is one of the most biologically diverse floras in the world. Considerable legal and conservation attention is given to rare plants in California. However, there is no information as to the research effort given to rare species in California. Here we ask the question: Is there more research done on rare plants in California than on non-rare species? To answer this question, we quantified the amount of literature available on Google Scholar for California’s rare plants, weeds, and non-rare natives. To account for the differences in species geographic extent, we aggregated occurrence data for each species from GBIF to determine their ranges. We found that rare species were severely under-represented in the literature, even after accounting for the differences in species extent

The diffusion-induced nova scenario. CK Vul and PB 8 as possible observational counterparts

We propose a scenario for the formation of DA white dwarfs with very thin helium buffers. For these stars we explore the possible occurrence of diffusion-induced CNO- flashes, during their early cooling stage. In order to obtain very thin helium buffers, we simulate the formation of low mass remnants through an AGB final/late thermal pulse (AFTP/LTP scenario). Then we calculate the consequent white dwarf cooling evolution by means of a consistent treatment of element diffusion and nuclear burning. Based on physically sounding white dwarf models, we find that the range of helium buffer masses for these diffusion-induced novas to occur is significantly smaller than that predicted by the only previous study of this scenario. As a matter of fact, we find that these flashes do occur only in some low-mass (M < 0.6M) and low metallicity (Z_ZAMS <0.001) remnants about 10^6 - 10^7 yr after departing from the AGB. For these objects, we expect the luminosity to increase by about 4 orders of magnitude in less than a decade. We also show that diffusion-induced novas should display a very typical eruption lightcurve, with an increase of about a few magnitudes per year before reaching a maximum of M_V ~ -5 to -6. Our simulations show that surface abundances after the outburst are characterized by logNH/NHe ~ -0.15...0.6 and N>C>O by mass fractions. Contrary to previous speculations we show that these events are not recurrent and do not change substantially the final H-content of the cool (DA) white dwarf. (Abridged)Comment: 16 pages, 8 figures, 3 tables. Replaced to match the final version published by MNRAS. The definitive version is available at http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291365-296

Timing of progression from Chlamydia trachomatis infection to pelvic inflammatory disease: a mathematical modelling study

PMCID: PMC3505463The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2334/12/187. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Traitement de la schistosomiase à S. mansoni : quelle alternative au praziquantel ?

Les schistosomiases sont des maladies parasitaires causées par des helminthes du genre Schistosoma (S.) qui touchent 200 millions de personnes dans le monde, mais restent rares chez le voyageur. Contrairement à S. heamatobium, agent de la bilharziose urinaire, S. mansoni, présent en Afrique subsaharienne, en Egypte ainsi qu'aux Antilles, au Surinam et dans le nordest du Brésil, est responsable des formes hépato-intestinales de la maladie. Les larves, vivant en eaux douces contaminées par des selles infectées, peuvent pénétrer la peau des baigneurs sans que l'individu ne s'en rende compte. Les parasites adultes s'établissent dans le système veineux digestif où ils se reproduisent et excrètent des oeufs qui migreront dans la lumière intestinale. Cette revue systématique évalue les effets des médicaments antibilharziens, utilisés seuls ou en association, pour traiter l'infection à S. mansoni

Age difference between heterosexual partners in Britain: Implications for the spread of Chlamydia trachomatis

Heterosexual partners often differ in age. Integrating realistic patterns of sexual mixing by age into dynamic transmission models has been challenging. The effects of these patterns on the transmission of sexually transmitted infections (STI) including Chlamydia trachomatis (chlamydia), the most common bacterial STI are not well understood. We describe age mixing between new heterosexual partners using age- and sex-specific data about sexual behavior reported by people aged 16-63 years in the 2000 and 2010 British National Surveys of Sexual Attitudes and Lifestyles. We incorporate mixing patterns into a compartmental transmission model fitted to age- and sex-specific, chlamydia positivity from the same surveys, to investigate C. trachomatis transmission. We show that distributions of ages of new sex partners reported by women and by men in Britain are not consistent with each other. After balancing these distributions, new heterosexual partnerships tend to involve men who are older than women (median age difference 2, IQR -1, 5 years). We identified the most likely age combinations of heterosexual partners where incident C. trachomatis infections are generated. The model results show that in >50% of chlamydia transmitting partnerships, at least one partner is ≥25 years old. This study illustrates how sexual behavior data can be used to reconstruct detailed sexual mixing patterns by age, and how these patterns can be integrated into dynamic transmission models. The proposed framework can be extended to study the effects of age-dependent transmission on incidence in any STI

Individual and Population Level Effects of Partner Notification for Chlamydia trachomatis

10.1371/journal.pone.0051438PLoS ONE712

An upper limit to the secular variation of the gravitational constant from white dwarf stars

A variation of the gravitational constant over cosmological ages modifies the main sequence lifetimes and white dwarf cooling ages. Using an state-of-the-art stellar evolutionary code we compute the effects of a secularly varying G on the main sequence ages and, employing white dwarf cooling ages computed taking into account the effects of a running G, we place constraints on the rate of variation of Newton's constant. This is done using the white dwarf luminosity function and the distance of the well studied open Galactic cluster NGC 6791. We derive an upper bound G'/G ~ -1.8 10^{-12} 1/yr. This upper limit for the secular variation of the gravitational constant compares favorably with those obtained using other stellar evolutionary properties, and can be easily improved if deep images of the cluster allow to obtain an improved white dwarf luminosity function.Comment: 15 pages, 4 figures, accepted for publication in JCA

Characterization of Urban Agricultural Practices and Gardeners’ Perceptions in Bronx Community Gardens, New York City.

This study investigates urban agricultural practices in the community gardens in the Bronx, New York City, United States, due to their historical role of helping bring peace and a sense of community to areas that suffered from violence and social injustice. Through semi-structured interviews with the gardeners, visits to observe the gardens, and a spatial analysis of community socio-demographic characteristics using Geographic Information Systems (GIS), we characterize the community gardens visited, and survey the gardeners’ perceptions regarding the benefits and challenges that are involved in the activity. The GISc analysis results showed that there is a much higher rate of poverty in block group populations living within a quarter mile of the community gardens and there is also a significantly higher Hispanic population in block groups living close to the gardens than those further away. The community gardens visited can be characterized as places where the activity of growing plants is a way to socialize within the community, a source of fresh vegetables and fruits, a way to beautify the neighborhood, and a place for education. Regarding the gardeners’ perceptions, it was unanimous that in the garden they enjoy being together with family and community, appreciating nature, and receiving therapeutic benefits that gardening brings. However, some have spoken about their fears of losing the gardens, since they are still not protected by the City, and are prone to take-over by developers

Most and Least Preferred Colours Differ According to Object Context : New Insights from an Unrestricted Colour Range

Humans like some colours and dislike others, but which particular colours and why remains to be understood. Empirical studies on colour preferences generally targeted most preferred colours, but rarely least preferred (disliked) colours. In addition, findings are often based on general colour preferences leaving open the question whether results generalise to specific objects. Here, 88 participants selected the colours they preferred most and least for three context conditions (general, interior walls, t-shirt) using a high-precision colour picker. Participants also indicated whether they associated their colour choice to a valenced object or concept. The chosen colours varied widely between individuals and contexts and so did the reasons for their choices. Consistent patterns also emerged, as most preferred colours in general were more chromatic, while for walls they were lighter and for t-shirts they were darker and less chromatic compared to least preferred colours. This meant that general colour preferences could not explain object specific colour preferences. Measures of the selection process further revealed that, compared to most preferred colours, least preferred colours were chosen more quickly and were less often linked to valenced objects or concepts. The high intra- and inter-individual variability in this and previous reports furthers our understanding that colour preferences are determined by subjective experiences and that most and least preferred colours are not processed equally

Discovery of near-ultraviolet counterparts to millisecond pulsars in the globular cluster 47 Tucanae

We report the discovery of the likely white dwarf companions to radio millisecond pulsars 47 Tuc Q and 47 Tuc S in the globular cluster 47 Tucanae. These blue stars were found in near-ultraviolet images from the Hubble Space Telescope for which we derived accurate absolute astrometry, and are located at positions consistent with the radio coordinates to within 0.016 arcsec (0.2sigma). We present near-ultraviolet and optical colours for the previously identified companion to millisecond pulsar 47 Tuc U, and we unambiguously confirm the tentative prior identifications of the optical counterparts to 47 Tuc T and 47 Tuc Y. For the latter, we present its radio-timing solution for the first time. We find that all five near-ultraviolet counterparts have U300-B390 colours that are consistent with He white dwarf cooling models for masses ~0.16-0.3 Msun and cooling ages within ~0.1-6 Gyr. The Ha-R625 colours of 47 Tuc U and 47 Tuc T indicate the presence of a strong Ha absorption line, as expected for white dwarfs with an H envelope.Comment: Accepted for publication on MNRAS. 12 pages, 5 figures, 3 table