West Midlands development : selection of areas for development

BEFORE commencing any clearing or fencing on a new property it is most important to carefully select those areas which are to be developed first

Core to surface excitations on GaAs(110)

We have carried out ab initio calculations of surface core excitations on finite cluster models of the GaAs(110) surface. For the Ga core excitation we find a localized excited state involving excitation into the empty Ga-4p orbital and bound with respect to the conduction band minimum (CBM) by 0.7 eV. This is in reasonable agreement with experiment (binding energy >~0.8 eV). This transition, which is not analogous to bulk core excitations, is termed a core surfaston to emphasize the character of the state. We find that the As core surfaston is above the CBM by 1.0 eV and hence should be difficult to observe

DSC of Milk Fats from Various Animals with High Levels of Medium-Chain, Unsaturated and Polyunsaturated Fatty Acids

Mammals of different species provide milk lipids with a wide variety of fatty acid composition yet with common stereospecific features. This allows the investigation of crystallographic properties of milk lipids that cannot be achieved by interesterified lipids due to the random stereospecific distribution that is obtained. The milk fats of elephant and white rhinoceros contain high amounts of 8:0, 10:0 and 12:0 which form triglyceride species that melt between 8 and 22 °C. The crystallographic behaviour of the milk lipids from blesbok and blue wildebeest differ from the other ruminant lipids, and that of horse and vervet monkey differ from the other non-ruminant lipids. It seems that a low content of 18:0 and 18:1, and a high content of saturated short- to medium-length fatty acids prevent the formation of the high and low temperature melting isotherms, between 35 and 42 °C, and between –45 and –10 °C, respectively, which are normally observed for milk fats.Keywords: Triglyceride, differential scanning calorimetry, milk, medium-chain fatty acid, polyunsaturated fatty aci

(Re)connect social and environmental responsibility to learners’ living environments: Curriculum challenges and possible solutions for teaching-learning in Life Orientation

An analysis of the National Curriculum Statement indicates a strong focus on the promotion of knowledge in local context, whilst being sensitive to global imperatives. This implies that learning experiences must reflect local realities first; a call which compels teachers to adapt their teaching with the purpose to make learning relevant and meaningful for the learner. It is therefore an appropriate time to ask the key question: Do Life Orientation teachers (re)connect their teaching-learning on social and environmental responsibility with learners’ living environments to adhere to curriculum requirements of relevance and meaningfulness? The qualitative data obtained from 13 structured classroom observations, with specific reference to the topic social and environmental responsibility, revealed that Life Orientation teachers experienced challenges. Based on these qualitative findings the researchers propose place-based education as an appropriate teaching-learning strategy to (re)connect social and environmental responsibility with the learner’s living environment

Chemisorption of Al and Ga on the GaAs (110) surface

We have studied the initial stages of the chemisorption of Al and Ga on the clean GaAs (110) surface by applying quantum chemical methods to small clusters representing Al or Ga on GaAs (110). These calculations suggest that at smallest coverages Al or Ga bind to a surface Ga atom; for higher coverages Al and the surface Ga interchange positions. We have obtained the binding energy, the chemical shifts of the Ga–3d, As–3d and Al–2p states, and the microscopic dipole associated with chemisorption of Al or Ga on GaAs (110). These results are compared to experimental values and further experiments are suggested

Awareness, perceived risk and practices related to cervical cancer and Pap smear screening: A crosssectional study among HIV-positive women attending an urban HIV clinic in Johannesburg, South Africa

Background. Cervical cancer is a major cause of cancer-related deaths, especially in the context of the HIV epidemic.Objective. To examine awareness, perceived risk and practices related to cervical cancer screening among HIV-positive women.Methods. Interviewer-administered structured questionnaires were administered to HIV-positive women (aged ≥18 years) enrolled in a cervical cancer screening study at the Themba Lethu Clinic, Johannesburg, South Africa, from November 2009 to December 2011. Modified Poisson regression with robust standard errors was used to identify factors at enrolment associated with awareness, perceived risk and adequate practice related to cervical screening. Adjusted relative risks (aRRs) with 95% confidence intervals (CIs) are presented.Results. Of the 1 202 women enrolled, 71.3% and 18.2% were aware of the Pap smear and HPV, respectively. Of the 1 192 participants with data evaluated, 76.5% were worried and 23.5% were not worried about cervical cancer; 28.6% of the women had adequate screening practice. Older age (40 - 49 years or ≥50 years v. 18 - 29 years) (aRR 1.63, 95% CI 1.12 - 2.37; aRR 2.22, 95% CI 1.44 - 3.41), higher education (tertiary v. less than grade 10) (aRR 1.39, 95% CI 1.00 - 1.93), initiation on combination antiretroviral therapy (aRR 1.36, 95% CI 1.00 - 1.85) and awareness of Pap smear screening (aRR 16.18, 95% CI 7.69 - 34.01) were associated with adequate screening practice.Conclusions. High levels of Pap smear awareness and low levels of Pap smear screening uptake were observed. However, Pap smear awareness was associated with adequate screening practice. More research into effective health education programmes to address these gaps is needed

Geometry of the abrupt (110) Ge/GaAs interface

We have studied the structure relaxation at the abrupt (110) Ge/GaAs interface by applying quantum chemical methods to clusters modeling this interface. Application of this model to bulk Ge and to bulk GaAs leads to theoretical Ge–Ge and Ga–As bond distances of 2.452 and 2.451 Å, respectively, in good agreement with the experimental values of 2.450 and 2.448 Å, respectively. Application of the model to the Ge/GaAs (110) interface indicates that this interface is nearly ideal. We find a very slight reconstruction at the interface leading to a Ge–Ga bond distance which is 0.04 Å longer than the Ge–As bond distance of 2.430 Å. The calculated spacing of the interface layer is 2.3% greater than that of bulk Ge or bulk GaAs

Theoretical studies of the reconstruction of the (110) surface of III–V and II–VI semiconductor compounds

We have studied the reconstruction of the (110) surface of various III–V semiconductor compounds (GaAs, GaP, GaN, AlAs, AlP, AlN, BAs, BP, BN) by applying quantum chemical methods to small clusters representative of these surfaces. Application of these techniques to GaAs (110) leads to a surface shear (0.67 Å) in excellent agreement with experimental values (0.65–0.70 Å). The results lead to trends in the surface distortions and reconstruction consistent with those predicted from local valence considerations. Possibilities for the electronic structure of II–VI semiconductor compounds are also considered