Characterization of Alkanethiolate Self-assembled Monolayers on Zinc Selenide Thin Films

Alkanethiolate self-assembled monolayers (SAMs) have been formed on zinc selenide (ZnSe) through adsorption from solution. Zinc selenide as a SAM-supporting substrate is of particular interest due to its transparency in the infrared region of the electromagnetic spectrum, enabling interfacial interactions at the substrate surface to be studied through transmission IR spectroscopy. In the past, mechanically polished, optical quality ZnSe surfaces have been used to support SAM formation. This surface, however, typically has a rms roughness around 40 nm, meaning it cannot support highly-ordered SAMs. In order to promote more consistent formation of highly-ordered SAM, a smoother supporting substrate is required. A significantly smoother ZnSe surface has be produced through physical vapor deposition (PVD) onto silicon substrates. The PVD-generated zinc selenide thin film exhibits the same IR transparency as the mechanically polished substrate, but with a rms roughness in the range of 2.7 ± 0.9 nm, which is over an order of magnitude improvement in surface roughness. The thin film ZnSe-SAM system was characterized through Fourier Transform Infrared (FTIR) spectroscopy, contact angle goniometry and x-ray photoelectron spectroscopy (XPS). In the XPS spectra, the shifts and relative intensities of Zn 2p, Se 3d, S 2p, and C 1s peaks when SAMs adsorbed to the surface have been used to show whether the SAM is physiosorbed or chemisorbed. A significant shift in the S 2s peak for a ZnSe film with SAMs compared to free thiol literature values, which is indicative of a change in chemical environment, provides evidence for chemisorption of thiolate SAMs to the ZnSe thin film

First Order Calculation of the Inclusive Cross Section pp to ZZ by Graviton Exchange in Large Extra Dimensions

We calculate the inclusive cross section of double Z-boson production within large extra dimensions at the Large Hadron Collider (LHC). Using perturbatively quantized gravity in the ADD model we perform a first order calculation of the graviton mediated contribution to the pp to ZZ cross section. At low energies (e.g. Tevatron) this additional contribution is very small, making it virtually unobservable, for a fundamental mass scale above 2500 GeV. At LHC energies however, the calculation indicates that the ZZ-production rate within the ADD model should differ significantly from the Standard Model if the new fundamental mass scale would be below 15000 GeV. A comparison with the observed production rate at the LHC might therefore provide direct hints on the number and structure of the extra dimensions.Comment: 7 pages, 7 figures, accepted for publication in Phys. Rev.

Anomalous electromagnetic processes at high temperatures

Chiral theories of constituent quarks interacting with bosons and photons at high temperatures are studied. In the expected chirally symmetric phase effective electromagnetic anomalous couplings for e.g. $\pi \sigma \to \gamma \gamma, ~ \gamma \to \pi \pi \pi \sigma,$ etc., are derived by applying functional methods.Comment: 6 pages, LaTeX, Talk at the workshop on QCD: Confinement, Collisions, and Chaos, AUP Paris 199

Eta Carinae across the 2003.5 Minimum: Analysis in the visible and near infrared spectral region

We present an analysis of the visible through near infrared spectrum of Eta Carinae and its ejecta obtained during the "Eta Carinae Campaign with the UVES at the ESO VLT". This is a part of larger effort to present a complete Eta Carinae spectrum, and extends the previously presented analyses with the HST/STIS in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground based seeing and contributions of nebular scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments' apertures. This paper provides a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 A.Comment: 13 pages, 11 figures + atlas. The paper accepted for the ApJS and is accompanied with an atlas in the online edition pape

Public sector nurses in Swaziland: can the downturn be reversed?

BACKGROUND: The lack of human resources for health (HRH) is increasingly being recognized as a major bottleneck to scaling up antiretroviral treatment (ART), particularly in sub-Saharan Africa, whose societies and health systems are hardest hit by HIV/AIDS. In this case study of Swaziland, we describe the current HRH situation in the public sector. We identify major factors that contribute to the crisis, describe policy initiatives to tackle it and base on these a number of projections for the future. Finally, we suggest some areas for further research that may contribute to tackling the HRH crisis in Swaziland. METHODS: We visited Swaziland twice within 18 months in order to capture the HRH situation as well as the responses to it in 2004 and in 2005. Using semi-structured interviews with key informants and group interviews, we obtained qualitative and quantitative data on the HRH situation in the public and mission health sectors. We complemented this with an analysis of primary documents and a review of the available relevant reports and studies. RESULTS: The public health sector in Swaziland faces a serious shortage of health workers: 44% of posts for physicians, 19% of posts for nurses and 17% of nursing assistant posts were unfilled in 2004. We identified emigration and attrition due to HIV/AIDS as major factors depleting the health workforce. The annual training output of only 80 new nurses is not sufficient to compensate for these losses, and based on the situation in 2004 we estimated that the nursing workforce in the public sector would have been reduced by more than 40% by 2010. In 2005 we found that new initiatives by the Swazi government, such as the scale-up of ART, the introduction of retention measures to decrease emigration and the influx of foreign nurses could have the potential to improve the situation. A combination of such measures, together with the planned increase in the training capacity of the country's nursing schools, could even reverse the trend of a diminishing health workforce. CONCLUSION: Emigration and attrition due to HIV/AIDS are undermining the health workforce in the public sector of Swaziland. Short-term and long-term measures for overcoming this HRH crisis have been initiated by the Swazi government and must be further supported and increased. Scaling up antiretroviral treatment (ART) and making it accessible and acceptable for the health workforce is of paramount importance for halting the attrition due to HIV/AIDS. To this end, we also recommend exploring ways to make ART delivery less labour-intensive. The production of nurses and nursing assistants must be urgently increased. Although the migration of HRH is a global issue requiring solutions at various levels, innovative in-country strategies for retaining staff must be further explored in order to stem as much as possible the emigration from Swaziland

Bridging properties of multiblock copolymers.

Using self-consistent field theory, we attempt to elucidate the links between microscopically determined properties, such as the bridging fraction of chains, and mechanical properties of multiblock copolymer materials. We determine morphological aspects such as period and interfacial width and calculate the bridging fractions, and compare with experimental data

The effect of bariatric surgery type on cardiac reverse remodelling

Introduction: Bariatric surgery is effective in reversing adverse cardiac remodelling in obesity. However, it is unclear whether the three commonly performed operations; Roux-en-Y Gastric Bypass (RYGB), Laparoscopic Sleeve Gastrectomy (LSG) and Laparoscopic Adjustable Gastric Band (LAGB) are equal in their ability to reverse remodelling. Methods: Fifty-eight patients underwent CMR to assess left ventricular mass (LVM), LV mass:volume ratio (LVMVR) and LV eccentricity index (LVei) before and after bariatric surgery (26 RYGB, 22 LSG and 10 LAGB), including 46 with short-term (median 251–273 days) and 43 with longer-term (median 983–1027 days) follow-up. Abdominal visceral adipose tissue (VAT) and epicardial adipose tissue (EAT) were also assessed. Results: All three procedures resulted in significant decreases in excess body weight (48–70%). Percentage change in VAT and EAT was significantly greater following RYGB and LSG compared to LAGB at both timepoints (VAT:RYGB −47% and −57%, LSG −47% and −54%, LAGB −31% and −25%; EAT:RYGB −13% and −14%, LSG –16% and −19%, LAGB −5% and −5%). Patients undergoing LAGB, whilst having reduced LVM (−1% and −4%), had a smaller decrease at both short (RYGB: −8%, p < 0.005; LSG: −11%, p < 0.0001) and long (RYGB: −12%, p = 0.009; LSG: −13%, p < 0.0001) term timepoints. There was a significant decrease in LVMVR at the long-term timepoint following both RYGB (−7%, p = 0.006) and LSG (−7%, p = 0.021), but not LAGB (−2%, p = 0.912). LVei appeared to decrease at the long-term timepoint in those undergoing RYGB (−3%, p = 0.063) and LSG (−4%, p = 0.015), but not in those undergoing LAGB (1%, p = 0.857). In all patients, the change in LVM correlated with change in VAT (r = 0.338, p = 0.0134), while the change in LVei correlated with change in EAT (r = 0.437, p = 0.001). Conclusions: RYGB and LSG appear to result in greater decreases in visceral adiposity, and greater reverse LV remodelling with larger reductions in LVM, concentric remodelling and pericardial restraint than LAGB

Robin conditions on the Euclidean ball

Techniques are presented for calculating directly the scalar functional determinant on the Euclidean d-ball. General formulae are given for Dirichlet and Robin boundary conditions. The method involves a large mass asymptotic limit which is carried out in detail for d=2 and d=4 incidentally producing some specific summations and identities. Extensive use is made of the Watson-Kober summation formula.Comment: 36p,JyTex, misprints corrected and a section on the massive case adde