Thumbs Up: The Lived Spatio-Temporal Experiences of a Young Female Solo-Hitchhiker

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The Gaze of the Yellow Clog Man

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Attenuated Virulence and Biofilm Formation in Staphylococcus aureus following Sublethal Exposure to Triclosan

Sub-effective exposure of Staphylococcus aureus to the biocide triclosan can reportedly induce a small colony variant (SCV) phenotype in Staphylococcus aureus. S. aureus SCVs are characterised by slow growth rates, reduced pigmentation and lowered antimicrobial susceptibility. Whilst they may exhibit enhanced intracellular survival, there are conflicting reports regarding their pathogenicity. The current study reports the characteristics of a SCV-like strain of S. aureus, created by repeated passage on sub-lethal triclosan concentrations. S. aureus ATCC 6538 (P0) was serially exposed ten times to concentration gradients of triclosan to generate strain P10. This strain was then further passaged ten times on triclosan-free medium (designated x10). The minimum inhibitory and bactericidal concentrations of triclosan for P0, P10 and x10 were determined and growth rates measured in biofilm and planktonic culture. Haemolysin, DNAse and coagulase activities were measured and virulence determined using a Galleria mellonella pathogenicity model. Strain P10 exhibited decreased susceptibility to triclosan and characteristics of a SCV phenotype, including considerably reduced growth rate and the formation of pinpoint colonies. However, this strain also had delayed coagulase production, impaired haemolysis (p<0.01), was defective in biofilm formation and DNAase activity, and displayed significantly attenuated virulence. Colony size, haemolysis, coagulase activity and virulence were only partially restored in strain x10, whereas planktonic growth rate was fully restored. However, x10 was at least as defective in biofilm formation and DNAse production as P10. These data suggest that although repeated exposure to triclosan may result in a SCV-like phenotype, this is not necessarily associated with increased virulence, and adapted bacteria may exhibit other functional deficiencies

Altered competitive fitness, antimicrobial susceptibility, and cellular morphology in a triclosan-induced small-colony variant of staphylococcus aureus

Staphylococcus aureus can produce small-colony variants (SCVs) that express various phenotypes. While their significance is unclear, SCV propagation may be influenced by relative fitness, antimicrobial susceptibility, and the underlying mechanism. We have investigated triclosan-induced generation of SCVs in six S. aureus strains, including methicillin-resistant S. aureus (MRSA). Parent strains (P0) were repeatedly passaged on concentration gradients of triclosan using a solid-state exposure system to generate P10. P10 was subsequently passaged without triclosan to generate X10. Susceptibility to triclosan and 7 antibiotics was assessed at all stages. For S. aureus ATCC 6538, SCVs were further characterized by determining microbicide susceptibility and competitive fitness. Cellular morphology was examined using electron microscopy, and protein expression was evaluated through proteomics. Triclosan susceptibility in all SCVs (which could be generated from 4/6 strains) was markedly decreased, while antibiotic susceptibility was significantly increased in the majority of cases. An SCV of S. aureus ATCC 6538 exhibited significantly increased susceptibility to all tested microbicides. Cross-wall formation was impaired in this bacterium, while expression of FabI, a target of triclosan, and IsaA, a lytic transglycosylase involved in cell division, was increased. The P10 SCV was 49% less fit than P0. In summary, triclosan exposure of S. aureus produced SCVs in 4/6 test bacteria, with decreased triclosan susceptibility but with generally increased antibiotic susceptibility. An SCV derived from S. aureus ATCC 6538 showed reduced competitive fitness, potentially due to impaired cell division. In this SCV, increased FabI expression could account for reduced triclosan susceptibility, while IsaA may be upregulated in response to cell division defects

Seagrass meadows

List of excluded full-text articles and the primary reason for exclusion. (DOCX 45 kb

Park Supply and Demand Part II: Downtown Silver Spring

Final project for URSP688M: Planning Technologies (Spring 2018). University of Maryland, College Park.As Downtown Silver Spring continues to urbanize, it becomes increasingly important to provide its residents and workforce with adequate recreational space. In conjunction with the the Maryland- National Capital Park and Planning Commission (M-NCPPC), this report investigates which areas of Downtown Silver Spring are adequately served by parks and those that lack robust access to these facilities. Using an ArcGIS-based model that combines pedestrian and bicycle access, population demographics, and data on local parks, our model assesses the degree to which Downtown Silver Spring’s residents and workforce have adequate access to parks. The report begins with a literature review on the value of parks and summarizes ways that supply and demand for recreational space have been geospatially analyzed. The second section details the methodology used to create the supply and demand model. The results section offers an analysis of gaps in park supply and demand, combining findings with population and workforce data. The report concludes with a list of recommendations to assist M-NCPPC in planning for parks in Downtown Silver Spring. Part I: http://hdl.handle.net/1903/21104Downtown Silver Sprin

Interpretación errónea del concepto de entropía

Background Cetylpyridinium chloride (CPC) and sodium fluoride augment oral hygiene by inactivating bacteria and inhibiting enamel demineralisation, respectively. However, there are few reports in the literature documenting the antibacterial efficacy of their combined use in mouthrinses. We have used six experimental systems to compare the antibacterial effects of mouthrinses containing 0.075 % CPC (test rinse, TR) or 0.075 % CPC with sodium fluoride (test fluoride rinse, TFR). Results Effects against planktonic bacteria were determined using viable counting (for Streptococcus mutans and salivary bacteria), a redox dye (for Actinomyces viscosus and salivary bacteria) and viable counting (for ex vivo oral rinses). Effects against saliva-derived biofilms were quantified using confocal microscopy and differential viable counting. Inhibition of biofilm formation was evaluated by pre-treating hydroxyapatite coupons with mouthrinses prior to inoculation. Otherwise-identical controls without CPC (control rinse and control fluoride rinse, CR and CFR, respectively), were included throughout. Compared to the controls, TFR and TR demonstrated significant antimicrobial effects in the redox assays, by viable counts (>3 log reductions) and in oral rinse samples (>1.25 log reductions, p 3 log difference, p < 0.05). Overall, there were no consistent differences in the activities of TR and TFR. Conclusions Sodium fluoride did not influence the antibacterial and anti-biofilm potency of CPC-containing formulations, supporting the combined use of CPC and sodium fluoride in mouthrinses to control oral bacteria and protect tooth enamel

Parks & Open Space: A Demand & Supply Analysis of Existing Public and Private Open Space in Montgomery County, Maryland

Final project for URSP688L: Planning Technologies (Fall 2017). University of Maryland, College Park.Montgomery County Planning’s Energized Public Spaces Functional Master Plan (EPS FMP), which focused primarily on the Silver Spring Central Business District, inventoried the supply of existing parks and open spaces, estimated the demand for parks and open space based on the presence of population and jobs, and identified areas where service gaps exist. The Fall 2017 URSP688L PALS program took the same approach as the EPS FMP, but expanded the study to the whole County, establishing a Set 1 Data and Map. We then created an alternative framework analysis using additional variables to further expand the study’s scope to establish a Set 2 Data and Map. In this alternative framework analysis (Set 2), the park supply for Montgomery County was determined by assigning a score based on amenities in each park. A walkshed was created for each park and the acre grid of Montgomery County in which it is located using a walkshed network analysis that calculated a one mile walk distance from each grid. Park demand was determined by including the following variables: population density, housing density, age, zero car households, and access to private gardens/yards, based on whether a property was multi-family or not. By analyzing the data on public and semi-public parks and factors known to influence their demand, we developed a composite scoring system to identify current service gaps in park lands within Montgomery County, and compared the Set 1 and Set 2 Data. The Set 2 data indicated more significant service gaps in park supply and demand throughout the County, but both Set 1 and Set 2 data indicated a need for more parks in the County’s more rural north and west areas. We recommend undertaking further research using additional variables and advanced analysis tools as this project proceeds into Spring 2018. Part II: http://hdl.handle.net/1903/21108Montgomery Count