The use of RAPD amplified DNA as markers for virulence characteristics in soybean cyst nematode

En vue de reconnaître la virulence de certaines souches du nématode à kystes du soja envers des cultivars résistants de soja, il a été procédé à une évaluation des potentialités de discrimination de tests "dot-blot", après amplification de l'ADN par RAPD. Une amorce de RAPD sépare deux souches du nématode du nord de l'Indiana ayant des niveaux comparables de virulence envers des lignées résistantes de soja, de deux souches du sud de l'Indiana présentant des caractères de virulence différents. Une sonde moléculaire pour les tests "dot-blot" a été également mise au point. Cette étude montre la possibilité de mettre au point, à partir de RAPD, des tests permettant de reconnaître les grands groupes de souches du nématode ayant des caractères communs de virulence envers les cultivars résistants de soja. (Résumé d'auteur

Early stage morphology of quench condensed Ag, Pb and Pb/Ag hybrid films

Scanning Tunneling Microscopy (STM) has been used to study the morphology of Ag, Pb and Pb/Ag bilayer films fabricated by quench condensation of the elements onto cold (T=77K), inert and atomically flat Highly Oriented Pyrolytic Graphite (HOPG) substrates. All films are thinner than 10 nm and show a granular structure that is consistent with earlier studies of QC films. The average lateral diameter, $\bar {2r}$, of the Ag grains, however, depends on whether the Ag is deposited directly on HOPG ($\bar {2r}$ = 13 nm) or on a Pb film consisting of a single layer of Pb grains ($\bar {2r}$ = 26.8 nm). In addition, the critical thickness for electrical conduction ($d_{G}$) of Pb/Ag films on inert glass substrates is substantially larger than for pure Ag films. These results are evidence that the structure of the underlying substrate exerts an influence on the size of the grains in QC films. We propose a qualitative explanation for this previously unencountered phenomenon.Comment: 11 pages, 3 figures and one tabl

Control of an atom laser using feedback

A generalised method of using feedback to control Bose-Einstein condensates is introduced. The condensates are modelled by the Gross-Pitaevskii equation, so only semiclassical fluctations can be suppressed, and back-action from the measurement is ignored. We show that for any available control, a feedback scheme can be found to reduce the energy while the appropriate moment is still dynamic. We demonstrate these schemes by considering a condensate trapped in a harmonic potential that can be modulated in strength and position. The formalism of our feedback scheme also allows the inclusion of certain types of non-linear controls. If the non-linear interaction between the atoms can be controlled via a Feshbach resonance, we show that the feedback process can operate with a much higher efficiency.Comment: 6 pages, 7 figure

Recruitment and retention strategies for community-based longitudinal studies in diverse urban neighborhoods

Longitudinal, natural experiments provide an ideal evaluation approach to better understand the impact of built environment interventions on community health outcomes, particularly health disparities. As there are many participant engagement challenges inherent in the design of large-scale community-based studies, adaptive and iterative participant engagement strategies are critical. This paper shares practical lessons learned from the Physical Activity and Redesigned Community Spaces (PARCS) study, which is an evaluation of the impact of a citywide park renovation initiative on physical activity, psychosocial health, and community well-being. The PARCS study, although ongoing, has developed several approaches to improve participant engagement: building trust with communities, adapting the study protocol to meet participants’ needs and to reflect their capacity for participation, operational flexibility, and developing tracking systems. These strategies may help researchers anticipate and respond to participant engagement challenges in community-based studies, particularly in low-income communities of color

Correlates of accelerometry non-adherence in an economically disadvantaged minority urban adult population

Objectives: The purpose of this study was to examine socio-demographic and psychosocial correlates of non-adherence to an accelerometry protocol in an economically disadvantaged urban population. Design: Cross-sectional study. Methods: We analyzed 985 New York City adult participants aged 18–81 years from the Physical Activity and Redesigned Community Spaces (PARCS) study. Participants were asked to wear a hip-worn ActiGraph GT3X-BT accelerometer for one week. Adherent accelerometer wear was defined as ≥3 days of ≥8 h/day of wear over a 7-day period and non-adherent accelerometry wear was defined as any wear less than adherent wear from returned accelerometers. Examined correlates of adherence included sociodemographic and psychosocial characteristics (e.g., general physical/mental health-related quality of life, self-efficacy for exercise, stress, sense of community/neighborhood well-being, and social cohesion). Results: From the total sample, 636 (64.6%) participants provided adherent wear and 349 (35.4%) provided non-adherent wear. In multivariable analysis, younger age (odds ratio [OR] = 0.63, 95% confidence interval [CI]: 0.53–0.75), poorer health-related quality of life (OR = 0.80, 95% CI: 0.65–0.98 for physical health and OR = 0.77, 95% CI: 0.62–0.94 for mental health), lower sense of community (OR = 0.79, 95% CI: 0.62–1.00) and current smoking status (OR = 1.97, 95% CI: 1.35–2.86) were associated with non-adherent wear. Conclusions: Non-adherent wear was associated with younger age, smoking, and lower self-reported physical/mental functioning and sense of community. This information can inform targeted adherence strategies to improve physical activity and sedentary behavior estimates from accelerometry data in future studies involving an urban minority population

The Role of the Physical and Social Environment in Observed and Self-Reported Park Use in Low-Income Neighborhoods in New York City

Physical and social environments of parks and neighborhoods influence park use, but the extent of their relative influence remains unclear. This cross-sectional study examined the relationship between the physical and social environment of parks and both observed and self-reported park use in low-income neighborhoods in New York City. We conducted community- (n = 54 parks) and individual-level (n = 904 residents) analyses. At the community level, observed park use was measured using a validated park audit tool and regressed on the number of facilities and programmed activities in parks, violent crime, stop-and-frisk incidents, and traffic accidents. At the individual level, self-reported park use was regressed on perceived park quality, crime, traffic-related walkability, park use by others, and social cohesion and trust. Data were collected in 2016–2018 and analyzed in 2019–2020. At the community level, observed park use was negatively associated with stop-and-frisk (β = −0.04; SE = 0.02; p < 0.05) and positively associated with the number of park facilities (β = 1.46; SE = 0.57; p < 0.05) and events (β = 0.16; SE = 0.16; p < 0.01). At the individual level, self-reported park use was positively associated with the social cohesion and trust scale (β = 0.02; SE = 0.01; p < 0.05). These results indicate that physical and social attributes of parks, but not perceptions of parks, were significantly associated with park use. The social environment of neighborhoods at both community and individual levels was significantly related to park use. Policies for increasing park use should focus on improving the social environment of parks and surrounding communities, not only parks' physical attributes. These findings can inform urban planning and public health interventions aimed at improving the well-being of residents in low-income communities

Genetic diversity between mouse strains allows identification of the CC027/GeniUnc strain as an orally reactive model of peanut allergy

Background: Improved animal models are needed to understand the genetic and environmental factors that contribute to food allergy. Objective: We sought to assess food allergy phenotypes in a genetically diverse collection of mice. Methods: We selected 16 Collaborative Cross (CC) mouse strains, as well as the classic inbred C57BL/6J, C3H/HeJ, and BALB/cJ strains, for screening. Female mice were sensitized to peanut intragastrically with or without cholera toxin and then challenged with peanut by means of oral gavage or intraperitoneal injection and assessed for anaphylaxis. Peanut-specific immunoglobulins, T-cell cytokines, regulatory T cells, mast cells, and basophils were quantified. Results: Eleven of the 16 CC strains had allergic reactions to intraperitoneal peanut challenge, whereas only CC027/GeniUnc mice reproducibly experienced severe symptoms after oral food challenge (OFC). CC027/GeniUnc, C3H/HeJ, and C57BL/6J mice all mounted a T H 2 response against peanut, leading to production of IL-4 and IgE, but only the CC027/GeniUnc mice reacted to OFC. Orally induced anaphylaxis in CC027/GeniUnc mice was correlated with serum levels of Ara h 2 in circulation but not with allergen-specific IgE or mucosal mast cell protease 1 levels, indicating systemic allergen absorption is important for anaphylaxis through the gastrointestinal tract. Furthermore, CC027/GeniUnc, but not C3H/HeJ or BALB/cJ, mice can be sensitized in the absence of cholera toxin and react on OFC to peanut. Conclusions: We have identified and characterized CC027/GeniUnc mice as a strain that is genetically susceptible to peanut allergy and prone to severe reactions after OFC. More broadly, these findings demonstrate the untapped potential of the CC population in developing novel models for allergy research