Conceptual aspects of line tensions

We analyze two representative systems containing a three-phase-contact line: a liquid lens at a fluid--fluid interface and a liquid drop in contact with a gas phase residing on a solid substrate. We discuss to which extent the decomposition of the grand canonical free energy of such systems into volume, surface, and line contributions is unique in spite of the freedom one has in positioning the Gibbs dividing interfaces. In the case of a lens it is found that the line tension is independent of arbitrary choices of the Gibbs dividing interfaces. In the case of a drop, however, one arrives at two different possible definitions of the line tension. One of them corresponds seamlessly to that applicable to the lens. The line tension defined this way turns out to be independent of choices of the Gibbs dividing interfaces. In the case of the second definition,however, the line tension does depend on the choice of the Gibbs dividing interfaces. We provide equations for the equilibrium contact angles which are form-invariant with respect to notional shifts of dividing interfaces which only change the description of the system. Conceptual consistency requires to introduce additional stiffness constants attributed to the line. We show how these constants transform as a function of the relative displacements of the dividing interfaces. The dependences of the contact angles on lens or drop volumes do not render the line tension alone but a combination of the line tension, the Tolman length, and the stiffness constants of the line.Comment: 34 pages, 9 figure

Soft Photons in Hadron-Hadron Collisions: Synchrotron Radiation from the QCD Vacuum?

We discuss the production of soft photons in high energy hadron-hadron collisions. We present a model where quarks and antiquarks in the hadrons emit ``synchrotron light'' when being deflected by the chromomagnetic fields of the QCD vacuum, which we assume to have a nonperturbative structure. This gives a source of prompt soft photons with frequencies $\omega <= 300 MeV$ in the c.m. system of the collision in addition to hadronic bremsstrahlung. In comparing the frequency spectrum and rate of ``synchrotron'' photons to experimental results we find some supporting evidence for their existence. We make an exclusive--inclusive connection argument to deduce from the ``synchrotron'' effect a behaviour of the neutron electric formfactor $G_E^n(Q^2)$ proportional to $(Q^2)^{1/6}$ for $Q^2 < 20 fm^{-2}$. We find this to be consistent with available data. In our view, soft photon production in high energy hadron-hadron and lepton-hadron collisions as well as the behaviour of electromagnetic hadron formfactors for low $Q^2$ are thus sensitive probes of the nonperturbative structure of the QCD vacuum.Comment: Heidelberg preprint HD-THEP-94-36, 31 pages, LaTeX + ZJCITE.sty (included), 12 figures appended as uuencoded compressed ps-fil

Rehabilitation and Exercise Oncology Program: Translating Research into a Model of Care

Introduction: The Rehabilitation and Exercise Oncology model of care (ActivOnco) was established to optimize cancer survivorship through exercise prescription and active lifestyle promotion, providing a transition of care from hospital to community. Patients having any cancer diagnosis, stage of disease, and treatment were eligible for evaluation and exercise prescription upon deterioration of performance status. The team of professionals included hospital-based physiotherapists proactively screening for rehabilitation needs, loss of functional independence, and exercise eligibility, plus exercise specialists in a community-based Wellness Centre to provide follow-up or direct access for post-treatment or non-complex patients. Methods: From January 2011 to December 2015, the hospital team assessed 1635 patients representing all major cancer sites, and the Wellness Centre team evaluated and prescribed exercise for 1066 participants. Primary interventions provided were education about fatigue management, physical activity promotion, exercise prescription, fracture risk reduction, referral to specialized follow-up services (for example, occupational therapy, lymphedema clinic), and coordination for mobility aids and paratransit services. Results and Conclusions: Implementation of the ActivOnco model of care showed that exercise alone is not a panacea for all functional deterioration associated with the cancer trajectory and its treatment. However, screening to identify rehabilitation needs combined with exercise prescription can effectively improve the quality of survivorship in cancer patients. Program developments are limited by the cost of human resources, lack of hospital-based physical resources, and lack of public funding, all of which significantly limit the scope and development of appropriate services