In situ analysis of C-C chemokine mRNA in human glomerulonephritis

Islets of Langerhans are microorgans scattered throughout the pancreas, and are responsible for synthesizing and secreting pancreatic hormones. While progress has recently been made concerning cell differentiation of the islets of Langerhans, the mechanism controlling islet morphogenesis is not known. It is thought that these islets are formed by mature cell association, first differentiating in the primitive pancreatic epithelium, then migrating in the extracellular matrix, and finally associating into islets of Langerhans. This mechanism suggests that the extracellular matrix has to be degraded for proper islet morphogenesis. We demonstrated in the present study that during rat pancreatic development, matrix metalloproteinase 2 (MMP-2) is activated in vivo between E17 and E19 when islet morphogenesis occurs. We next demonstrated that when E12.5 pancreatic epithelia develop in vitro, MMP-2 is activated in an in vitro model that recapitulates endocrine pancreas development (Miralles, F., P. Czernichow, and R. Scharfmann. 1998. Development. 125: 1017-1024). On the other hand, islet morphogenesis was impaired when MMP-2 activity was inhibited. We next demonstrated that exogenous TGF-beta1 positively controls both islet morphogenesis and MMP-2 activity. Finally, we demonstrated that both islet morphogenesis and MMP-2 activation were abolished in the presence of a pan-specific TGF-beta neutralizing antibody. Taken together, these observations demonstrate that in vitro, TGF-beta is a key activator of pancreatic MMP-2, and that MMP-2 activity is necessary for islet morphogenesis.     

Confined phonons in Si nanowires

Raman microprobe studies of long crystalline Si nanowires reveal for the first time the evolution of phonon confinement with wire diameter. The Raman band at approximately 520 cm-1 in bulk Si is found to downshift and asymmetrically broaden to lower frequency with decreasing wire diameter D, in good agreement with a phenomenological model first proposed by Richter et al. An adjustable parameter (alpha) is added to the theory that defines the width of the Gaussian phonon confinement function. We find that this parameter is not sensitive to diameter over the range 4-25 nm.     

A new agricultural drought monitoring index combining MODIS NDWI and day–night land surface temperatures: a case study in China

The vegetation health index (VHI) is a widely utilized remote-sensing-based index for monitoring agricultural drought on the regional or global scale. However, the validity of VHI as a drought detection tool relies on the assumption that the normalized difference vegetation index (NDVI) and land-surface temperature (T_s) at a given pixel will vary inversely over time. This assumption may introduce large uncertainties in VHI for drought monitoring over areas with complex landforms, such as China. In order to monitor agricultural drought over the whole of China, a new drought detection index is suggested in this article, termed the vegetation drought index (VDI). VDI is developed from the classical VHI by substituting NDVI and T_s with the normalized difference water index (NDWI) and day–night T_s difference (?T_s), respectively. Terra Moderate Resolution Imaging Spectroradiometer (MODIS) MOD11C3 and MOD13C2 products from 2001 to 2011, monthly precipitation data from 1970 to 2010, and yearly winter wheat yield data from 2000 to 2012 were utilized to evaluate VDI. Results indicated that (1) many areas in China show a positive correlation between NDVI and T_s, especially in the cold season, whereas most areas have a negative correlation between NDWI and ?T_s; (2) VDI has a significant linear correlation with VHI in areas and periods where the NDVI–T_s correlation and NDWI–?T_s correlation are both negative; (3) VDI presents a significant correlation with 3 and 6 month standardized precipitation indices, which is comparable to VHI; and (4) VDI has a significant correlation with normalized crop yield, and is better than VHI. As an example, the extreme drought event over southwestern China from winter 2009 to spring 2010 was successfully explored by VDI. It is concluded that the new index, VDI, has the potential to monitor agricultural drought over the whole of China, including areas and periods where the NDVI–T_s correlation is non-negative.     

Radiological assessment of the structural shielding adequacy of the radiotherapy facility at Korle-Bu Teaching Hospital, Accra, Ghana

A (60)Co radiotherapy source with an initial activity of 185 TBq has exhausted its useful half-life and has been replaced with a 222 TBq (60)Co source at the Korle-Bu Teaching Hospital; a radiological assessment was performed to ascertain the shielding integrity of the facility. Dose rate at selected critical positions were calculated for the old and new sources. Dose rate measurements were also performed at these critical locations for the new source. The dose rates at all the critical locations of the public and staff access areas were within the recommended dose rate limit of 0.5 and 7.5 μSv h(-1) for the public and controlled area, respectively. The concrete biological shielding at the facility at the moment is adequate enough to attenuate the gamma photons from the new 222 TBq (60)Co source. High dose rates were recorded at the entrance to the treatment room, it is therefore recommended that optimisation of procedures should be encouraged to restrict activities in this area.     

Radiation doses and hazards from processing of crude oil at the Tema oil refinery in Ghana

Processing of crude oil has been carried out in Ghana for more than four decades without measures to assess the hazards associated with the naturally occurring radionuclides in the raw and processed materials. This study investigates the exposure of the public to (226)Ra, (232)Th and (40)K in crude oil, petroleum products and wastes at the Tema oil refinery in Ghana using gamma-ray spectrometry. The study shows higher activity concentrations of the natural radionuclides in the wastes than the crude oil and the products with estimated hazard indices less than unity. The values obtained in the study are within recommended limits for public exposure indicating that radiation exposure from processing of the crude oil at the refinery does not pose any significant radiological hazard but may require monitoring to establish long-term effect on both public and workers.     

Raman spectroscopy and structure of crystalline gallium phosphide nanowires

Gallium phosphide nanowires with a most probable diameter of approximately 20.0 nm and more than 10 microns in length have been synthesized by pulsed laser vaporization of a heated GaP/5% Au target. The morphology and microstructure of GaP nanowires have been investigated by scanning electron microscopy and transmission electron microscopy. Twins have been observed along the crystalline nanowires, which have a growth direction of [111]. Raman scattering shows a 4 cm-1 downshift of the longitudinal optical phonon peak in the nanowire with respect to the bulk; the transverse optical phonon frequency and line width are, however, the same as in the bulk. The quantum confinement model first proposed by Richter et al. cannot explain the observed behavior of the Raman modes.     

To what extent does organizational learning influence the stakeholder pressure–green procurement nexus? Evidence from Ghana

The United Nations has described global warming as reaching a code red point for humanity and requires drastic measures to avert further terrible warming. Green procurement practices have been recognized as sustainable measures towards a low carbon trajectory, yet its implementation is still at the embryonic stage mainly due to weaknesses in organizational creativity skills and learning strategies. For the first time, we provide a theoretical framework that links stakeholder pressure, organizational learning, green procurement, and environmental performance within a public–private partnership environment. The analysis in this study is performed using the partial least square structural equation modelling and a sample of 295 respondents from Ghanaian infrastructure projects. Overall, we have found that exploratory and exploitative learning are necessary to translate stakeholder pressure to implement green procurement practices effectively. Also, firms that yield to stakeholder pressure develop their creative skills and increase their environmental performance. We recommend that managers should consider frequent market research and consistent stakeholder dialogue to create a culture of learning towards green practice implementation and promote environmental sustainability.