Effects of Electron Correlations on Hofstadter Spectrum

By allowing interactions between electrons, a new Harper's equation is derived to examine the effects of electron correlations on the Hofstadter energy spectra. It is shown that the structure of the Hofstadter butterfly ofr the system of correlated electrons is modified only in the band gaps and the band widths, but not in the characteristics of self-similarity and the Cantor set.Comment: 13 pages, 5 Postscript figure

Action semantics in retrospect

This paper is a themed account of the action semantics project, which Peter Mosses has led since the 1980s. It explains his motivations for developing action semantics, the inspirations behind its design, and the foundations of action semantics based on unified algebras. It goes on to outline some applications of action semantics to describe real programming languages, and some efforts to implement programming languages using action semantics directed compiler generation. It concludes by outlining more recent developments and reflecting on the success of the action semantics project

Geographic Distribution of Childbirth among Adolescents in Cameroon from 2003 to 2005

Objective. To determine the frequency and the trend of adolescents (10–19 years) in childbirth within a period of 3 years in referral maternity units in Cameroon. Method. Descriptive and retrospective study for a 3-year period (2003–2005) in referral maternity units headed by a qualified Obstetrician-Gynecologist. We analyzed the trend and geographic distribution of 8222 adolescent deliveries over 3 years. Epi Info 3.5 software was used for data analysis. Chi square test for trend was used to assess the contribution of adolescent deliveries over years. The trend was considered significant if P < .05. Results. During the period of the study, there was a total of 8387 deliveries. We excluded 165 women because of lack of information about age. We therefore included a total of 8222 adolescent deliveries. Overall, the contribution of adolescents to deliveries ranged from 6.87% to 26.51%, depending on the region with a national mean of 14.23%. Adolescents aged 16 or less contributed to 2.82% of deliveries while those aged from 17 to 19 contributed to 11.41%. The contribution of adolescents to deliveries decreased significantly over 3 years (P < .0001). Conclusion. The study underscores the importance of Public Health programs in strengthening maternity services for adolescents in Cameroon while taking into consideration geographic differences

Reflections on a 'virtual' practice development unit: changing practice through identity development

Aims. This paper draws together the personal thoughts and critical reflections of key people involved in the establishment of a ‘virtual’ practice development unit of clinical nurse specialists in the south of England. Background. This practice development unit is ‘virtual’ in that it is not constrained by physical or specialty boundaries. It became the first group of Trust-wide clinical nurse specialists to be accredited in the UK as a practice development unit in 2004. Design and methods. The local university was asked to facilitate the accreditation process via 11 two-hour audio-recorded learning sessions. Critical reflections from practice development unit members, leaders and university staff were written 12 months after successful accreditation, and the framework of their content analysed. Findings and discussion. Practice development was seen as a way for the clinical nurse specialists to realize their potential for improving patient care by transforming care practice in a collaborative, interprofessional and evolutionary manner. The practice development unit provided a means for these nurses to analyse their role and function within the Trust. Roberts’ identity development model for nursing serves as a useful theoretical underpinning for the reflections contained in this paper. Conclusions. These narratives provide another example of nurses making the effort to shape and contribute to patient care through organizational redesign. This group of nurses began to realize that the structure of the practice development unit process provided them with the means to analyse their role and function within the organization and, as they reflected on this structure, their behaviour began to change. Relevance to clinical practice. Evidence from these reflections supports the view that practice development unit participants have secured a positive and professional identity and are, therefore, better able to improve the patient experience

The investigation on properties of sodium sulfate-activated mortar incorporating steel slag with various replacement ratio and particle size

The alkali-activated materials are alternatives for replacing Portland cement to manufacture concrete products, which has benefits on reducing carbon dioxide (CO2) emission and supporting the development of green sustainable construction. The combined use of steel slag (SS) and alkali activator (AA) to make alkali-activated concrete not only reuse the industrial waste but also improve the activity of SS. There are many types of chemicals can be used as AA, such as sodium silicate, sodium hydroxide, sodium carbonate and sodium sulfate (SST). In this study, SST was chosen as the AA, and the performance of alkali-activated mortar incorporating SS from 0 to 12.5% of Portland cement by mass, activated by SST with the dosage varying from 0 to 3% of cement by mass, was investigated. In addition, two types of SS, of which the particle sizes are less than 75 μm and 150 μm, were used to manufacture alkali-activated SS mortar. Flow table test, compressive strength test and flexural strength test were conducted to evaluate the fresh and hardened properties of alkali-activated steel slag (AA-SS) mortar. Response surface methodology (RSM) was used in this study as an analysis method. As result, the addition of SS tends to decrease the strength of mortar, while the addition of SST could lead to the increase in the strength of mortar

Mechanical and water absorption properties of cement mortar incorporating basic oxygen furnace slag as fine aggregate

The steel industries produce much waste called steel slag (SS) which can be classified into three broad classification namely basic oxygen furnace slag (BOFS), electric arc furnace slag (EAFS) and ladle furnace slag (LFS). The disposal of these SS resulted in land occupation, water pollution and other environmental issues. The aim of this research is to study the performance of cement mortar by using BOFS as partial sand replacement. The properties of both fresh and hardened mortar containing 10%, 20% and 30% of BOFS with particle size <0.15mm were examined. The mechanical properties of BOFS mortars were tested at 1, 7, 28 and 60 days. While for water absorption, it was conducted only at 28 days. Results show that the increase of BOFS causes reduction in workability and water absorption which indicates good improvement in the water tightness of mortar. From the perspective of compressive strength, the replacement of BOFS increases the strength up to 14% compared to the reference specimen at 28 days. The compressive strength and flexural strength development in the mortar with 20% BOFS content yielded the highest strength gains compared to all specimens at later age

Working and learning across professional boundaries

This paper focuses on a context where interdisciplinarity intersects with interprofessionality: the work of children's services professionals who address the needs of children identified as vulnerable. It draws on evidence and perspectives from two disciplines - educational studies and health care - to consider the issues and challenges posed by learning and/or working across disciplinary boundaries and why these have proved so obdurate

Towards a critical epidemiology approach for applied sexual health research

Critical approaches may benefit epidemiological studies of sexual health. This article proposes a critical approach, reconcilable with social epidemiological enquiry. Key aims of critical epidemiology for sexual health are identified, from which three criticisms of practice emerge: (1) lack of attention to socio-cultural contexts, (2) construction of 'risk' as residing in the individual and (3) enactment of public health agendas which privilege and pathologise certain behaviours. These reflect and construct an apolitical understanding of population health. This article proposes features of a critical epidemiology that represent a morally driven re-envisioning of the focus, analysis and interpretation of epidemiological studies of sexual health