Thioglycolic acid on the gold (111) surface and Raman vibrational spectra

The interaction of thioglycolic acid with the Au(111) surface is investigaged, and it is found that at the low coverage the molecule lies down on the substrate. If the mercaptan-hydrogen atom is eliminated, the resulting SCH_2COOH molecule is randomly oriented on the surface. If the carboxylic acid group in the HSCH_2COOH molecule is deprotonated instead, the HSCH_2COO^ molecule lies down on the surface. However, when the mercaptan-hydrogen atom in the HSCH_2COO^- molecule is removed, the resulting SCH_2COO^- molecule rises up to a certain level on the substrate. The calculated Raman vibrational spectra decipher which compounds and atomic displacements contribute to the corresponding frequencies. We thus propose a consistent mechanism for the deposition of thioglycolic acid on the Au(111) surface.Comment: 18 pages, 5 figures, submitted to J. Chem. Phy

Implementing performance management at local government level in South Africa : a case study on the impact of organisational culture

Local Government in South Africa has undergone much transformation since 2000. Although much of the change has been to correct imbalances, inequities and disparities within our local communities as a result of Apartheid, change has also been motivated by National Government’s realisation that, as with governments throughout the world, there is a need to modernise all spheres of Government. Part of this transformation process at a local government level in South Africa has been to ensure that municipalities become more responsive to the communities’ needs. The guiding principles for this transformation are contained in the White Paper on the Transformation of the Public Service (1995) and the Batho Pele White Paper (1997). This has informed the Municipal Systems Act: Act 32 of 2000 of which Chapter 6 determines that municipalities will have a performance management system to promote a culture of performance management amongst the political structures, political office bearers, councillors and administration. The performance management system must ensure that the municipality administers its affairs in an economical, effective, efficient and accountable manner. A literature review contained in this research, indicates that internationally, implementing performance management systems at a local government level is impact upon by a number of factors such as the organizational culture of an institution. This research, which has been grounded within a constructivist paradigm, describes the impact organizational culture has had on the implementation process of the performance management system at Buffalo City Municipality. Interviews were conducted amongst the Section 57 employees (i.e. the Directors) and those employees directly responsible for implementing performance management. The four Directors, two General Managers and the portfolio councilor were interviewed. Semi-structured interviews were conducted with the interviewees and this culminated in a total of 10 hours of interviewing. The protocols were analyzed using the guidelines suggested by Boyatzis (1998) and the findings are detailed in two chapters. The findings of the research were that the implementation of the performance management system at Buffalo City Municipality has been impacted on by the dichotomy between the political and administrative leadership, resulting in non-implementation of council resolutions, the lack of an organizational strategy, poor institutional arrangements and inadequate resource allocation, are reported. However, the most important finding was the impact that a culture of fear has had on the implementation process. This culture of fear and its impact on the implementation of performance management system is described as the most pervasive and insidious of all the findings to have negatively impacted on the implementation process. This research ends with recommendations for further research and it is argued that each organization has its own unique organizational culture. The conclusion is that no single typology, as contained in the literature, which can account for the specific impact organizational culture will have on the implementation process of a performance management system at local government level in South Africa. Consequently, implementers of performance management systems must assess the unique characteristics of each organization’s culture prior to implementation, in order to evaluate its impact that the organizational culture can have on the process

How does an external electrical field affect adsorption patterns of thiol and thiolate on the gold substrate ?

The responsive behavior of methanethiol and methylthiolate molecules on the Au(111) surface with an applied electrical potential is studied, and it is shown how the sulfur adsorption site, the S-H bond orientation and the interacting energy change with an external electric field strength. The electron charge density corresponding to an electric field minus that obtained in zero field, with zero-field optimal geometry, is calculated to explain the responsive behavior. The interacting energy for the intact methanethiol adsorption is larger than that for the dissociative one, showing that an external electric field can not make the hydrogen dissociate from the sulfur.Comment: 11 pages, 3 figures, LaTe

Assessing handheld mobile laser scanners for forest surveys

Abstract: A handheld mobile laser scanning (HMLS) approach to forest inventory surveying allows virtual reconstructions of forest stands and extraction of key structural parameters from beneath the canopy, significantly reducing survey time when compared against static laser scan and fieldwork methods. A proof of concept test application demonstrated the ability of this technique to successfully extract diameter at breast height (DBH) and stem position compared against a concurrent terrestrial laser scan (TLS) survey. When stems with DBH > 10 cm are examined, an HMLS to TLS modelling success rate of 91% was achieved with the root mean square error (RMSE) of the DBH and stem position being 1.5 cm and 2.1 cm respectively. The HMLS approach gave a survey coverage time per surveyor of 50 m 2/min compared with 0.85 m2/min for the TLS instrument and 0.43 m2/min for the field study. This powerful tool has potential applications in forest surveying by providing much larger data sets at reduced operational costs to current survey methods. HMLS provides an efficient, cost effective, versatile forest surveying technique, which can be conducted as easily as walking through a plot, allowing much more detailed, spatially extensive survey data to be collected

Crime sensing with big data: the affordances and limitations of using open-source communications to estimate crime patterns

This paper critically examines the affordances and limitations of big data for the study of crime and disorder. We hypothesise that disorder-related posts on Twitter are associated with actual police crime rates. Our results provide evidence that naturally occurring social media data may provide an alternative information source on the crime problem. This paper adds to the emerging field of computational criminology and big data in four ways: i) it estimates the utility of social media data to explain variance in offline crime patterns; ii) it provides the first evidence of the estimation offline crime patterns using a measure of broken windows found in the textual content of social media communications; iii) it tests if the bias present in offline perceptions of disorder is present in online communications; and iv) it takes the results of experiments to critically engage with debates on big data and crime prediction

The CH3SH molecule deposited on Cu(111) and deprotonation

We demonstrate for the first time that when a methanethiol adsorbed on the regular Cu(111) surface, the dissociative structure is thermodynamically more stable than the intact one. The computational results show that at low temperature the methanethiol adsorbate prefers the atop site of the regular Cu(111) surface. As the temperature is increased, the S-H bond is broken and the methylthiolate favors the hollow sites. On the defected Cu(111) surface, the dissociative configuration is still thermodynamically more stable than the nondissociative one. The calculation indicates that the hydrogen initially attached to the sulfur would like to form a bond with the copper surface rather than desorb from it. Even though both copper and gold are the noble metal, the stability of the methanethiol adsorption on the Cu(111) substrate is almost the reverse of that on the Au(111).Comment: 13 pages, 7 figures, submitted to Phys. Rev.

Two-dimensional magnetoexcitons in the presence of spin-orbit coupling

We study theoretically the effect of spin-orbit coupling on quantum well excitons in a strong magnetic field. We show that, in the presence of an in-plane field component, the excitonic absorption spectrum develops a double-peak structure due to hybridization of bright and dark magnetoexcitons. If the Rashba and Dresselhaus spin-orbit constants are comparable, the magnitude of splitting can be tuned in a wide interval by varying the azimuthal angle of the in-plane field. We also show that the interplay between spin-orbit and Coulomb interactions leads to an anisotropy of exciton energy dispersion in the momentum plane. The results suggest a way for direct optical measurements of spin-orbit parameters.Comment: 9 pages, 6 figure