UML Reflections

The UML shares with reflective architectures the idea that self-definition of languages and systems is a key principle for building and maintaining complex systems. The UML is now defined by a four-layer metalevel structure, enabling a flexible and extensible definition of models by metamodels, and even a self-description of the meta-metamodel (the MOF). This metalevel dimension of UML is currently restricted to structural reflection. But recently a new extension to the UML, called the Action Semantics (AS), has been proposed for standardization to the OMG. This paper explores how this proposed extension brings a behavioural reflection dimension to the UML. Indeed, we show that it is not only possible but quite e#ective to use the AS for manipulating UML models (including the AS metamodel). Besides elegant conceptual achievements, such as a metacircular definition of the AS, reflective modeling with the AS leverages on the UML metalevel architecture to provide the benefits of a reflective approach, in terms of separation of concerns, within a mainstream industrial context. A complete model can now be built as an ideal model representing the core concepts in the application, to which non-functional requirements are integrated as fully traceable transformations over this ideal model. For example, this approach paves the way for powerful UML-defined semantics-based model transformations such as refactoring, aspect weaving, application of design patterns or round-trip engineering

Semi-Analytic Approach to Higher-Order Corrections in Simple Muonic Bound Systems: Vacuum Polarization, Self-Energy and Radiative-Recoil

The current discrepancy of theory and experiment observed recently in muonic hydrogen necessitates a reinvestigation of all corrections to contribute to the Lamb shift in muonic hydrogen muH, muonic deuterium muD, the muonic 3He ion, as well as in the muonic 4He ion. Here, we choose a semi-analytic approach and evaluate a number of higher-order corrections to vacuum polarization (VP) semi-analytically, while remaining integrals over the spectral density of VP are performed numerically. We obtain semi-analytic results for the second-order correction, and for the relativistic correction to VP. The self-energy correction to VP is calculated, including the perturbations of the Bethe logarithms by vacuum polarization. Subleading logarithmic terms in the radiative-recoil correction to the 2S-2P Lamb shift of order alpha (Zalpha)^5 mu^3 ln(Zalpha)/(m_mu m_N) are also obtained. All calculations are nonperturbative in the mass ratio of orbiting particle and nucleus.Comment: 10 pages; svjour style; to appear in the European Physical Journal

Strategic engagement and librarians

The future of the academic book is a strategic engagement issue for librarians. Books might not be stored in or purchased for university libraries; they might not even exist in a physical form. How will academic books be organised and accessed in the future, if they are not in libraries? How will librarians at universities engage academic researchers in strategic conversations about the future of their academic books? This chapter argues that conversations between librarians and academic book authors about the future are more important than ever. It puts the current challenges in context, using data from the Research Excellence Framework and the University of Nottingham library catalogue, identifying the strategic role of librarians in shaping the future of the academic book through strategic engagement

Protection of pregnant women at work in Switzerland: implementation and experiences of maternity protection legislation

Objectives. Like most industrialized countries, Switzerland has introduced legislation to protect the health of pregnant workers and their unborn children from workplace hazards. This study aims to assess legislation’s degree of implementation in the French-speaking part of Switzerland and understand the barriers to and resources supporting its implementation. Methods. Data were collected using mixed methods: (1) an online questionnaire send to 333 gynecologist-obstetricians (GOs) and 637 midwives; (2) exploratory semi-structured interviews with 5 workers who had had a pregnancy in the last 5 years. Results. Questionnaire response rates were 32% for GOs and 54% for midwives. Data showed that several aspects of the implementation of maternity protection policies could be improved. Where patients encounter workplace hazards, GOs and midwives estimated that they only received a risk assessment from the employer in about 5% and 2% of cases, respectively. Preventive leave is underprescribed: 32% of GOs reported that they “often” or “always” prescribed preventive leave in cases involving occupational hazards; 58% of GOs reported that they “often” or “always” prescribed sick leave instead. Interviews with workers identified several barriers to the implementation of protective policies in workplaces: a lack of information about protective measures and pregnancy rights; organizational problems triggered by job and schedule adjustments; and discrepancies between some safety measures and their personal needs. Conclusions. Results demonstrate the need to improve the implementation and appropriateness of maternity protection legislation in Switzerland. More research is required to identify the factors affecting its implementation

The bound mu+ mu- system

We consider the hyperfine structure, the atomic spectrum and the decay channels of the bound mu+ mu- system (dimuonium). The annihilation lifetimes of low-lying atomic states of the system lie in the nanosecond range range. The decay rates could be measured by detection of the decay products (high energy photons or electron-positron pairs). The hyperfine structure splitting of the dimuonic system and its decay rate are influenced by electronic vacuum polarization effects in the far time-like asymptotic region. This constitutes a previously unexplored kinematic regime. We evaluate next--to-leading order radiative corrections to the decay rate of low-lying atomic states. We also obtain order alpha^5 corrections to the hyperfine splitting of the 1S and 2S levels.Comment: 10 figures (eps format) attached, Scheduled tentatively by PRA for Nov/Dec 199

Compromised cerebrovascular regulation and cerebral oxygenation in pulmonary arterial hypertension

Background : Functional cerebrovascular regulatory mechanisms are important for maintaining constant cerebral blood flow and oxygen supply in heathy individuals and are altered in heart failure. We aim to examine whether pulmonary arterial hypertension (PAH) is associated with abnormal cerebrovascular regulation and lower cerebral oxygenation and their physiological and clinical consequences. Methods and Results : Resting mean flow velocity in the middle cerebral artery mean flow velocity in the middle cerebral artery (MCAvmean); transcranial Doppler), cerebral pressure‐flow relationship (assessed at rest and during squat‐stand maneuvers; analyzed using transfer function analysis), cerebrovascular reactivity to CO2, and central chemoreflex were assessed in 11 patients with PAH and 11 matched healthy controls. Both groups also completed an incremental ramp exercise protocol until exhaustion, during which MCAvmean, mean arterial pressure, cardiac output (photoplethysmography), end‐tidal partial pressure of CO2, and cerebral oxygenation (near‐infrared spectroscopy) were measured. Patients were characterized by a significant decrease in resting MCAvmean (P<0.01) and higher transfer function gain at rest and during squat‐stand maneuvers (both P<0.05). Cerebrovascular reactivity to CO2 was reduced (P=0.03), whereas central chemoreceptor sensitivity was increased in PAH (P<0.01), the latter correlating with increased resting ventilation (R2=0.47; P<0.05) and the exercise ventilation/CO2 production slope (Embedded Image slope; R2=0.62; P<0.05) during exercise for patients. Exercise‐induced increases in MCAvmean were limited in PAH (P<0.05). Reduced MCAvmean contributed to impaired cerebral oxygen delivery and oxygenation (both P<0.05), the latter correlating with exercise capacity in patients with PAH (R2=0.52; P=0.01). Conclusions : These findings provide comprehensive evidence for physiologically and clinically relevant impairments in cerebral hemodynamic regulation and oxygenation in PAH

Assessment of Daily Life Physical Activities in Pulmonary Arterial Hypertension

Background: In pulmonary arterial hypertension (PAH), the six-minute walk test (6MWT) is believed to be representative of patient’s daily life physical activities (DLPA). Whether DLPA are decreased in PAH and whether the 6MWT is representative of patient’s DL PA remain unknown. Methods: 15 patients with idiopathic PAH (IPAH) and 10 patients with PAH associated with limited systemic sclerosis (PAH-SSc) were matched with 15 healthy control subjects and 10 patients with limited systemic sclerosis without PAH. Each subject completed a 6MWT. The mean number of daily steps and the mean energy expenditure and duration of physical activities.3 METs were assessed with a physical activity monitor for seven consecutive days and used as markers of DLPA. Results: The mean number of daily steps and the mean daily energy expenditure and duration of physical activities.3 METs were all reduced in PAH patients compared to their controls (all p,0.05). The mean number of daily steps correlated with the 6MWT distance for both IPAH and PAH-SSc patients (r = 0.76, p,0.01 and r = 0.85, p,0.01), respectively. Conclusion: DLPA are decreased in PAH and correlate with the 6MWT distance. Functional exercise capacity may thus be a useful surrogate of DL PA in PAH