2,478 research outputs found
Edge contact angle and modified Kelvin equation for condensation in open pores
We consider capillary condensation transitions occurring in open slits of
width and finite height immersed in a reservoir of vapour. In this case
the pressure at which condensation occurs is closer to saturation compared to
that occurring in an infinite slit () due to the presence of two
menisci which are pinned near the open ends. Using macroscopic arguments we
derive a modified Kelvin equation for the pressure, , at which
condensation occurs and show that the two menisci are characterised by an edge
contact angle which is always larger than the equilibrium contact
angle , only equal to it in the limit of macroscopic . For walls
which are completely wet () the edge contact angle depends only on
the aspect ratio of the capillary and is well described by for large . Similar results apply for condensation in
cylindrical pores of finite length. We have tested these predictions against
numerical results obtained using a microscopic density functional model where
the presence of an edge contact angle characterising the shape of the menisci
is clearly visible from the density profiles. Below the wetting temperature
we find very good agreement for slit pores of widths of just a few tens
of molecular diameters while above the modified Kelvin equation only
becomes accurate for much larger systems
New bulk scalar field solutions in brane worlds
We use nonlinear perturbation theory to obtain new solutions for brane world
models that incorporate a massive bulk scalar field. We then consider tensor
perturbations and show that Newtonian gravity is recovered on the brane for
both a light scalar field and for a bulk field with large negative mass. This
latter result points to the viability of higher-derivative theories of gravity
in the context of bulk extra dimensions.Comment: 4+\epsilon pages, no figure
Do Social Media Enhance Constructive Employee Voice All of the Time or Just Some of the Time?
Social media are becoming widely adopted by organizations to encourage collaboration and communication. We seek to understand how social media can enhance employee voice and employees’ willingness to engage in constructive dialogue with both colleagues and managers. By drawing on literature on employee voice, signalling theory and personal control to analyse qualitative data from research into three strategic business units in a major global telecommunications corporation, we find: (1) employee perceptions of personal control and autonomy influence whether and how employees’ exercise voice through social media; (2) these perceptions vary according to different organizational/field-level contexts evident in the corporation
Home sampling for sexually transmitted infections and HIV in men who have sex with men: a prospective observational study
To determine uptake of home sampling kit (HSK) for STI/HIV compared to clinic-based testing, whether the availability of HSK would increase STI testing rates amongst HIV infected MSM, and those attending a community-based HIV testing clinic compared to historical control. Prospective observational study in three facilities providing STI/HIV testing services in Brighton, UK was conducted. Adult MSM attending/contacting a GUM clinic requesting an STI screen (group 1), HIV infected MSM attending routine outpatient clinic (group 2), and MSM attending a community-based rapid HIV testing service (group 3) were eligible. Participants were required to have no symptomatology consistent with STI and known to be immune to hepatitis A and B (group 1). Eligible men were offered a HSK to obtain self-collected specimens as an alternative to routine testing. HSK uptake compared to conventional clinic based STI/HIV testing in group 1, increase in STI testing rates due to availability of HSK compared to historical controls in group 2 and 3, and HSK return rates in all settings were calculated. Among the 128 eligible men in group 1, HSK acceptance was higher (62.5% (95%CI: 53.5–70.9)) compared to GUM clinic-based testing (37.5% (95% CI: 29.1–46.5)), (p = 0.0004). Two thirds of eligible MSM offered an HSK in all three groups accepted it, but HSK return rates varied (highest in group 1, 77.5%, lowest in group 3, 16%). HSK for HIV testing was acceptable to 81%of men in group 1. Compared to historical controls, availability of HSK increased the proportion of MSM testing for STIs in group 2 but not in group 3. HSK for STI/ HIV offers an alternative to conventional clinic-based testing for MSM seeking STI screening. It significantly increases STI testing uptake in HIV infected MSM. HSK could be considered as an adjunct to clinic-based services to further improve STI/HIV testing in MSM
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