Three-dimensional field perspective on deformation, flow, and growth of the lower continental crust (Dharwar craton, India

The study of fabric development and juvenile batholith emplacement across the tilted crustal section of the Eastern Dharwar craton shows that horizontal, constrictional deformation affected large volumes of the midcrust and lower crust at the time of regional partial melting and magmatic accretion. Constriction is achieved by a combination of coeval shallow and steep planar fabrics sharing a common horizontal elongation direction, two sets of conjugate strike-slip shears, and extensional shear zones. The Eastern Dharwar craton illustrates an end-member deformation mode by which a particularly weakened lithosphere responds to shortening by developing distributed, horizontal plane strain on a crustal scale, resulting from the combination of crustal shortening and lateral gravity-driven flow. Thinning accompanying constrictional deformation is interpreted as compensating for juvenile magmatic accretion and thickening of greenstone belts and as acting to maintain a stable crustal thickness. Such a midcrustal to lower crustal deformation process may provide a resolution of the batholithic room problem in a softened crust submitted to lateral shortening and may explain nearly isobaric retrograde pressure-temperaturetime paths of high temperature - low pressure high-grade terrains

Strain patterns, décollement and incipient sagducted greenstone terrains in the Archaean Dharwar craton (south India)

The Archaean Dharwar craton is characterized by two greenstone successions: the > 3 Ga Sargur Group and the 3.0-2.5 Ga Dharwar Supergroup. Examples of both successions are described from the region of Jayachamarajapura where they are also distinguished by different tectonic patterns. The younger greenstones have undergone only minor deformation and are only slightly metamorphosed and so provide a good case study of the relative behavior of greenstones in relation to their granite-gneiss country rocks. A detailed structural analysis indicates two strain fields associated with two deformational episodes: D1 and D2. The D1 episode produced dome-and-basin structures and affected merely the older greenstones and the gneisses. The mapped strain field is compatible with the hypothesis that it is associated with the development of diapiric-type gravitational instabilities. The D2 episode affects only the younger greenstone belt, which has the overall geometry of a complex syncline. It is discordant over a complex of gneisses and older greenstones that was deformed during the D1 episode. The base of the discordant cover sequence is tectonized and constitutes a décollement surface. Kinematic criteria at this surface have opposite sense and converge towards the belt axis. These structural features are interpreted in terms of progressive deformation compatible with the incipient development of a sagducting trough. These results are consistent with those obtained from other parts of the craton, where the tectonic evolution appears to reflect mainly relative vertical displacements facilitated by the reheating of continental crust during two major Archaean tectonometamorphic episodes. Copyright © 1996 Elsevier Science Ltd

Potential of supercapacitors in novel power converters as semi-ideal lossless voltage droppers

Electrical physics text book theory tells us that charging a capacitor is much less efficient than replenishing the energy in a discharged electro-chemical battery. If a fully discharged capacitor is pumped with a charge of Q coulombs, it stores 1/2QV while dissipating the same amount of energy in the loop resistance. However, if the same charge is pumped into a re-chargeable electrochemical cell of voltage V the energy stored in the cell is QV, while the wasted energy is determined by the loop resistance and the voltage difference across the resistance. If a rechargeable battery pack is to be replaced by a supercapacitor module, this difference could seriously affect the design of power converters required, since the power converter should stop charging at a certain point to avoid overcharging the capacitor bank. However, if a useful resistive load such as heater, DC-DC converter, inverter or a lamp load is used as a part of the loop resistance in a capacitor charging loop, a significant part of this loss can be recovered. One example of this is in the supercapacitor assisted low drop-out regulator (SCALDO) technique. This paper will detail the concept of circumvention of RC loop charging loss, theoretically quantifying the same in a generalized circuit, demonstrating how this can be applied in completely novel circuit topologies such as the supercapacitor assisted LED (SCALED) converter. The paper will provide experimental results of selected SCALDO implementations and early results of SCALED technique to support this theory

Archean granite-greenstone tectonics at Kolar (South India): Interplay of diapirism and bulk inhomogeneous contraction during juvenile magmatic accretion

[1] The structural study of the Kolar greenstone belt and surrounding granite-gneiss terrains combined with U-Pb dating reveals that the middle and lower crustal tectonoplutonic pattern of the eastern Dharwar craton developed during a major magmatic accretion event between 2550 and 2530 Ma. The granite-greenstone pattern resulted from the interference of gravity-driven sagging of the greenstones (i.e., diapirism), E-W bulk inhomogeneous shortening combined with horizontal N-S stretching, and syntectonic juvenile pluton emplacement. Bulk inhomogeneous contraction is accommodated by the synchronous development of a pervasive, N-S trending vertical foliation, shallow stretching lineation, and conjugate strike-slip shear zone pattern within and outside the greenstone belt, resulting in regional horizontal pure shear deformation. The plutons around the greenstone belt record regional contraction by developing one set of strike-slip C-S fabrics of the shear zone pattern. The development of the granite-greenstone pattern was coeval and compatible with deformation during juvenile magmatic accretion, melting, and granulite metamorphism in the lower crust. The Kolar example points to a specific crustal rheology that allowed sagduction of the greenstones and regional distributed bulk inhomogeneous strain, due to mechanical homogeneity and low viscosity provided by large-scale melting during the accretion event. This example further suggests specific boundary conditions to the craton that allowed E-W inhomogeneous shortening to be accommodated by N-S stretching and spreading of the crust without significant tectonic thickening. Such tectonoplutonic pattern is specific to the Archean and may develop as a consequence of mantle plume activity in intracontinental settings

Regolith and landscape evolution in Peninsular India and West Africa: morphoclimatic evolution of the two continents over the Cenozoic

Shields’ surfaces of the tropical belt have been continuously shaped over the Cenozoic under the combined or alternating effects of chemical weathering and mechanical erosion that left stepped relict lateritic paleolandsurfaces exposing different generations and type of regolith in today’s sceneries. These lateritic paleolandscape remnants are well preserved in West Africa and in highland Peninsular India, particularly on Deccan Traps. The stepped character of such paleolandscape remnants allows to describing a common geomorphic sequence of three successive sub-continental scale lateritic paleolandsurfaces on the two sub regions. The first surface is defined by the oldest remnants, which are generally topped by Al-Fe (mostly bauxitic) lateritic duricrusts upon distant kmscale mesas or as larger provinces on high relictual topographic massifs (e.g., Fouta Djalon in West Africa or Nilgiri hills in South India). The relict bauxitic landforms generally dominate from less than ca. 300 m the relicts of a second geomorphic level (so-called “intermediate” surface), which is mantled by ferruginous lateritic duricrusts. The third and last paleolandsurface remnants lie less than ca. 400 m below the bauxitic landforms, and consist in a weathered lateritic pediment that is locally capped by a ferricrete. The ages of these continental-scale lateritic paleolandsurfaces may be bracketed using 40Ar/39Ar dating of K-Mn oxides (cryptomelane) formed in their underlying weathering profiles in the African and Indian contexts [1,2,3]. The first surface is Eocene and correlates with the Eocene climatic optimum (ca. 50 Ma) that is recorded throughout the tropical belt by the production of bauxite. In South India, the Intermediate surface has evolved by dominant chemical weathering since the Late Eocene (ca. 37 Ma) and records peak weathering activity in the Late Oligocene. In West Africa, that paleolandsurface seems to have only record the late Oligocene interval (ca. 29-24 Ma) of intense weathering. Abandonment of the Intermediate landscape as a result of its dissection by the river network took place in the Latest Oligocene on both continents. By contrast, the later pediment seems to have been shaped quite rapidly (ca. 32-29 Ma) and was weathered around the Oligocene- Miocene boundary (ca. 29-24 Ma) in India, whereas it took longer to form (ca. 24-18 Ma) and was weathered mostly during the Mid-Miocene (ca. 18-11 Ma) in West Africa. The contrasts in the morphoclimatic record of the two sub regions are linked to the spatial diversification of climatic regimes after the Eocene climatic optimum. However, the combination of the ages with the elevation differences between each lateritic paleolandsurface documents denudation rates with comparable and very low amplitudes (5-15 m/m.y.) in these two continents over the last 50 Ma. [1] Beauvais A and Chardon D (2013) Geochem Geophys Geosyst 14:1590-1608, doi:10.1002/ggge.20093. [2] Bonnet NJ et al. (2014) Earth Planet Sci Lett 386:126-137, doi:10.1016/j.epsl.2013.11.002 [3] Bonnet NJ et al. (2016) Chem Geol, in press

Symptoms of anxiety and depression in adolescent students; a perspective from Sri Lanka

Background: Sri Lanka recorded an extraordinary high suicide rate for adolescents aged 15 - 19 in the early 1990s (46.5/100,000). With this in perspective, the Ministry of Health in Sri Lanka recommends school programmes for adolescents by mental health units of local hospitals.Methods: We conducted cross sectional surveys to screen for symptoms of anxiety and depression among students aged 14 - 18 during school mental health programmes. Two schools were randomly selected within the Ratnapura municipality (urban population of approx. 50,000), Sri Lanka and all students aged 14-18 were assessed with self administered (pre tested, Sinhalese translations) questionnaires [Center for epidemiologic studies depression scale, Anxiety screening test of suicide and mental health association international].Results: A total of 445 students were assessed (male-54.4%, female 45.6%). Thirty six percent screened positive for depression (mild depression-17%, severe depression-19%) and 28% screened positive for severe anxiety. Females screened positive for depression and anxiety significantly more than the males (p = 0.0001, 0.005 respectively). Students in classes facing barrier examinations at the end of the year had the highest positivity rates. Examination related issues (36%) were the most commonly cited problem.Recommendations: It is recommended that:. 1. School mental health development programmes in Sri Lanka concentrate more on reducing examination related stress, and in particular focus on the female students. 2. Policy decisions are made to reduce competition for higher education. 3. A nationally coordinated survey on mental health of adolescent students is carried out utilizing the island-wide network of medical officers of mental health. © 2010 Rodrigo et al; licensee BioMed Central Ltd

Measurement of Pion Enhancement at Low Transverse Momentum and of the Delta-Resonance Abundance in Si-Nucleus Collisions at AGS Energy

We present measurements of the pion transverse momentum (p_t) spectra in central Si-nucleus collisions in the rapidity range 2.0<y<5.0 for p_t down to and including p_t=0. The data exhibit an enhanced pion yield at low p_t compared to what is expected for a purely thermal spectral shape. This enhancement is used to determine the Delta-resonance abundance at freeze-out. The results are consistent with a direct measurement of the Delta-resonance yield by reconstruction of proton-pion pairs and imply a temperature of the system at freeze-out close to 140 MeV.Comment: 12 pages + 4 figures (uuencoded at end-of-file

Performance of prototypes for the ALICE electromagnetic calorimeter

The performance of prototypes for the ALICE electromagnetic sampling calorimeter has been studied in test beam measurements at FNAL and CERN. A $4\times4$ array of final design modules showed an energy resolution of about 11% /$\sqrt{E(\mathrm{GeV})}$ $\oplus$ 1.7 % with a uniformity of the response to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV. The electromagnetic shower position resolution was found to be described by 1.5 mm $\oplus$ 5.3 mm /$\sqrt{E \mathrm{(GeV)}}$. For an electron identification efficiency of 90% a hadron rejection factor of $>600$ was obtained.Comment: 10 pages, 10 figure