Automated image analysis for experimental investigations of salt water intrusion in coastal aquifers

A novel methodology has been developed to quantify important saltwater intrusion parameters in a sandbox style experiment using image analysis. Existing methods found in the literature are based mainly on visual observations, which are subjective, labour intensive and limits the temporal and spatial resolutions that can be analysed. A robust error analysis was undertaken to determine the optimum methodology to convert image light intensity to concentration. Results showed that defining a relationship on a pixel-wise basis provided the most accurate image to concentration conversion and allowed quantification of the width of mixing zone between the saltwater and freshwater. A large image sample rate was used to investigate the transient dynamics of saltwater intrusion, which rendered analysis by visual observation unsuitable. This paper presents the methodologies developed to minimise human input and promote autonomy, provide high resolution image to concentration conversion and allow the quantification of intrusion parameters under transient conditions.

Experimental Saltwater Intrusion in Coastal aquifers Using Automated Image Analysis: Applications to Homogeneous Aquifers.

This paper presents the applications of a novel methodology to quantify saltwater intrusion parameters in laboratory-scale experiments. The methodology uses an automated image analysis procedure, minimizing manual inputs and the subsequent systematic errors that can be introduced. This allowed the quantification of the width of the mixing zone which is difficult to measure in experimental methods that are based on visual observations. Glass beads of different grain sizes were tested for both steady-state and transient conditions. The transient results showed good correlation between experimental and numerical intrusion rates. The experimental intrusion rates revealed that the saltwater wedge reached a steady state condition sooner while receding than advancing. The hydrodynamics of the experimental mixing zone exhibited similar
traits; a greater increase in the width of the mixing zone was observed in the receding saltwater wedge, which indicates faster fluid velocities and higher dispersion. The angle of intrusion analysis revealed the formation of a volume of diluted saltwater at the toe position when the saltwater wedge is prompted to recede. In addition, results of different physical repeats of the experiment produced an average coefficient of variation less than 0.18 of the measured toe length and width of the mixing zone.

Preoperative characteristics and compliance with follow-up after trabeculectomy surgery in rural southern China

Purpose: To evaluate preoperative characteristics and follow-up in rural China after trabeculectomy, the primary treatment for glaucoma there. Methods: Patients undergoing trabeculectomy at 14 rural hospitals in Guangdong and Guangxi Provinces and their doctors completed questionnaires concerning clinical and sociodemographic information, transportation, and knowledge and attitudes about glaucoma. Follow-up after surgery was assessed as cumulative score (1 week: 10 points, 2 weeks: 7 points, 1 month: 5 points). Results Among 212 eligible patients, mean preoperative presenting acuity in the operative eye was 6/120, with 61.3% (n=130) blind (≤6/60). Follow-up rates were 60.8% (129/212), 75.9% (161/212) and 26.9% (57/212) at 1 week, 2 weeks and 1 month, respectively. Patient predictors of poor follow-up included elementary education or less (OR=0.37, 95% CI 0.20 to 0.70, p=0.002), believing follow-up was not important (OR=0.62, 95% CI 0.41 to 0.94, p=0.02), lack of an accompanying person (OR=0.14, 95% CI 0.07 to 0.29, p<0.001), family annual income <US$800 (OR=0.28, 95% CI 0.11 to 0.72, p=0.008) and not requiring removal of scleral flap sutures postoperatively (OR=0.11, 95% CI 0.06 to 0.22, p<0.001). Age, sex, employment, travel distance/time/costs, patient preoperative clinical factors and physician factors were unassociated with follow-up. Conclusions: Follow-up after 2 weeks was inadequate to provide optimal clinical care, and surgery is being applied too late to avoid blindness in the majority of patients. Earlier surgery, support for return visits and better explanations of the importance of follow-up are needed. Directing all patients to return for possible scleral flap suture removal may be a valid strategy to improve follow-up.

Nutrient Dynamics in the EEZ of the West Coast of India with Special Reference to the Oxygen Minimum Zone and Denitrification

The present work aims at deciphering the processes that control the nutrient distribution along the EEZ (Exclusive Economic Zone of India) of the west coast of India and to bring out its linkage with primary and secondary productivity. This work assume utmost importance as very few studies have hitherto focused entirely on the EEZ of the west coast of India to address the biochemical responses brought about by monsoons. The present study examines the seasonal variations in physicochemical parameters and associated primary biological responses along the west coast of India. This study targets to measure and understand the shelf ocean exchange in a typical coastal upwelling region of the southeast Arabian Sea, and the influence of convective mixing along the northern part of the west coast of India. The study focuses more directly on coastal upwelling along the southwest coast of India, within the EEZ. The effects of coastal upwelling, eddy formation and the offshore advection are apparent in the present investigation. This has consequences to fisheries and climate, in energy transfer to the food chain and the increased sequestering of carbon in the ocean. The study also focuses on the Oxygen Minimum Zone (OMZ) and dentrification observed along the EEZ of the west coast of India on a seasonal scale. In the study, an attempt is also made to demarcate the geographical boundaries of the denitrification zone in the EEZ of India and on the nature and magnitude of these variations, on a seasonal and inter annual scales

The Cold Tongue in the South China Sea during Boreal Winter and Its Interaction with the Atmosphere

A distinct cold tongue has recently been noticed in the South China Sea during the winter monsoon, with the cold tongue temperature minimum occurring in the January or February. This cold tongue shows signi¯cant links with the Maritime Continent's rainfall during the winter period. The cold tongue and its interaction with the Maritime Continent's weather were studied using Reynolds SST data, wind ¯elds from the NCEP{NCAR reanalysis dataset and the quikSCAT dataset. In addition, rainfall from the GOES Precipitation Index (GPI) for the periods 2000 to 2008 was also used. The propagation of the cold tongue towards the south is explained using wind dynamics and the western boundary current. During the period of strong cold tongue, the surface wind is strong and the western boundary current advects the cold tongue to the south. During the period of strong winds the zonal gradient of SST is high [0.5±C (25 km)¡1]. The cold tongue plays an important role in regulating the climate over the Maritime Continent. It creates a zonal/meridional SST gradient and this gradient ultimately leads in the formation of convection. Hence, two maximum precipitation zones are found in the Maritime Continent, with a zone of relatively lower precipitation between, which coincides with the cold tongue's regions. It was found that the precipitation zones have strong links with the intensity of the cold tongue. During stronger cold tongue periods the precipitation on either side of the cold tongue is considerably greater than during weaker cold tongue periods. The features of convection on the eastern and western sides of the cold tongue behave di®erently. On the eastern side convection is preceded by one day with SST gradient, while on the western side it is four days.

ToxicMetals Enrichment in the Surficial Sediments of a Eutrophic Tropical Estuary (Cochin Backwaters, Southwest Coast of India)

Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surficial sediments of the Cochin backwaters were studied during both monsoon and pre-monsoon periods. Spatial variations were in accordance with textural charaterstics and organic matter content. A principal component analysis distinguished three zones with different metal accumulation capacity: (i) highest levels in north estuary, (ii) moderate levels in central zone, and (iii) lowest levels in southern part. Trace metal enrichments are mainly due to anthropogenic contribution of industrial, domestic, and agricultural effluents, whose effect is enhanced by settling of metals due to organic flocculation and inorganic precipitation associated with salinity changes. Enrichments factors using Fe as a normalizer showed that metal contamination was the product of anthropogenic activities. An assessment of degree of pollution-categorized sediments as moderately polluted with Cu and Pb, moderately-to-heavily polluted with Zn, and heavily-to-extremely polluted with Cd. Concentrations at many sites largely exceed NOAA ERL (e.g., Cu, Cr, and Pb) or ERM (e.g., Cd, Ni, and Zn). This means that adverse effects for benthic organisms are possible or even highly probable.

Implicaciones comerciales de la Diplomacia Petrolera China en el Amazonas ecuatoriano. 2007 - 2013

El presente Estudio de Caso tiene como objetivo analizar en qué medida las dinámicas comerciales de la Diplomacia Petrolera China han convertido a Ecuador en un socio estratégico para la RPCh. El petróleo como fuente de energía es primordial para llevar a cabo los procesos de industrialización y mantener el crecimiento económico del león Asiático. Por eso su búsqueda se ha convertido en un tema principal dentro de la agenda de política exterior. Ecuador, el tercer país de Suramérica con más reservas de petróleo, después de Venezuela y Brasil, se ha convertido en zona de influencia de la RPCh y a través de las empresas petroleras estatales se han firmado contratos por la venta de petróleo. A pesar de que las relaciones bilaterales son asimétricas, se buscar establecer si Ecuador es un socio estratégico en la región.

La política exterior energética China y sus implicaciones geopolíticas en Asia Central (2000 - 2010)

El interés de la presente monografía es evaluar las implicaciones geopolíticas que ha tenido la política exterior energética China dentro la región de Asia Central. De esta manera, se analiza el papel de los recursos energéticos en las dinámicas geopolíticas que se están dando en la región centroasiática, al igual que la influencia de grandes potencias en esta zona. Así, teniendo en cuenta la teoría geopolítica de Saúl Bernard Cohen se sostiene que el acercamiento de China, a través de su política exterior energética, ha ayudado a transformar a Asia Central en un shatterbelt debido a su intención de ejercer influencia y control sobre los recursos de la región.

Seasonal deposition of Holocene banded sediments in the Severn Estuary Levels (southwest Britain): palynological and sedimentological evidence

Banded sediments outcrop widely in the intertidal zone of the Severn Estuary and have been suggested, on the basis of textural analysis, to have formed in response to seasonal variations in sea temperature and windiness (Holocene, 14 (2004) 536). Here palynological and sedimentological analyses of banded sediments of mid-Holocene date from Gold Cliff, on the Welsh side of the Severn Estuary, are combined to test and further develop the hypothesis of seasonal deposition. Pollen percentage and concentration data are presented from a short sequence of bands to establish whether textural variations in the bands coincide with variations in pollen content reflecting seasonal flowering patterns. It is shown that fine-grained band parts contain higher total pollen concentrations, and a higher proportion of pollen from late spring- to summer-flowering plants, than coarse-grained band parts. Pollen in the coarser deposits appears primarily to reflect deposition from the buffering `reservoir' of suspended pollen in the estuarine water-body and from rivers, when there is little pollen in the air in winter, while the finer sediments contain pollen deposited from the atmosphere during the flowering season, superimposed on these `background' sources. The potential of such deposits for refining chronologies and identifying seasonality of coastal processes is noted, and the results of charcoal particle analysis of the bands presented as an example of how they have the potential to shed light on seasonal and annual patterns of human activity. (C) 2004 Elsevier Ltd. All rights reserved.

Field study on thermal comfort and adaptive strategies in residential buildings in China

This paper fully describes a nation-wide field study on building thermal environment and thermal comfort of occupant, which was carried out in summer 2005 and in winter 2006 respectively in China, illustrating the adaptive strategies adopted by occupants in domestic buildings in China. According to the climate division in China, the buildings in Beijing (BJ), Shanghai (SH), Wuhan (WH) and Chongqing (CQ), Guangzhou (GZ), Kunming (KM), were selected as targets which are corresponding to cold zone, hot summer and cold winter zone (SWC-SH, WH, CQ), hot summer and warm winter zone and temperate zone, respectively. The methodology used in the field study is the combination of subjective questionnaire regarding thermal sensation and adaptive approaches and physical environmental monitoring including indoor air temperature and relative humidity. A total of 1671 subjects participate in this investigation with more than 80% response rate in all surveyed cities. Both physiological and non-physiological factors (behavioural and psychological adaptations) have been analysed.

Timing and structure of the 8.2 kyr B.P. event inferred from δ18O records of stalagmites from China, Oman, and Brazil

Oxygen isotope records of stalagmites from China and Oman reveal a weak summer monsoon event, with a double-plunging structure, that started 8.21 ± 0.02 kyr B.P. An identical but antiphased pattern is also evident in two stalagmite records from eastern Brazil, indicating that the South American Summer Monsoon was intensified during the 8.2 kyr B.P. event. These records demonstrate that the event was of global extent and synchronous within dating errors of <50 years. In comparison with recent model simulations, it is plausible that the 8.2 kyr B.P. event can be tied in changes of the Atlantic Meridional Overturning Circulation triggered by a glacial lake draining event. This, in turn, affected North Atlantic climate and latitudinal position of the Intertropical Convergence Zone, resulting in the observed low-latitude monsoonal precipitation patterns.

An event of stratospheric air intrusion and its associated secondary surface cyclogenesis over the South Atlantic Ocean

This work presents an analysis of a lowermost stratospheric air intrusion event over the coast of Brazil, which may have been responsible for a secondary surface cyclogenesis over the southwestern Atlantic Ocean. The surface cyclone initiated at 0600 UTC 17 April 1999 in a cold air mass in the rear of a cold front after a primary cyclone developed over the same region. The analysis of the secondary cyclone revealed the presence of lowermost stratospheric air intrusion characterized by anomalous potential vorticity (PV), dry air, and high concentration of ozone in atmospheric column. The system developed on the eastern side of an upper level core of PV anomaly, which induced a cyclonic wind circulation at lower levels and favored the onset of the secondary cyclone. In midlevels (500 hPa), the cutoff low development contributed to reduce the propagation speed of the wave pattern. This feature seemed to (1) allow the low-level cold/dry air to heat/moisten associated with sensible and latent fluxes transferred from the ocean to the atmosphere, which intensified a baroclinic zone parallel to the coast, and (2) contribute to the long duration of the system. The present analysis indicates that this secondary cyclone development could be the result of the coupling between the PV anomaly in the upper levels and low-level air-sea interaction.

Timing and structure of the 8.2 kyr BP event inferred from delta(18)O records of stalagmites from China, Oman, and Brazil

Oxygen isotope records of stalagmites from China and Oman reveal a weak summer monsoon event, with a double-plunging structure, that started 8.21 +/- 0.02 kyr B. P. An identical but antiphased pattern is also evident in two stalagmite records from eastern Brazil, indicating that the South American Summer Monsoon was intensified during the 8.2 kyr B. P. event. These records demonstrate that the event was of global extent and synchronous within dating errors of <50 years. In comparison with recent model simulations, it is plausible that the 8.2 kyr B. P. event can be tied in changes of the Atlantic Meridional Overturning Circulation triggered by a glacial lake draining event. This, in turn, affected North Atlantic climate and latitudinal position of the Intertropical Convergence Zone, resulting in the observed low-latitude monsoonal precipitation patterns.

Columnar joints in the Patino Formation sandstones, Eastern Paraguay: a dynamic interaction between dyke intrusion, quartz dissolution and cooling-induced fractures

The Patino Formation sandstones, which crop out in Aregua neighborhood in Eastern Paraguay and show columnar joints near the contact zone with a nephelinite dyke, have as their main characteristics the high proportion of syntaxial quartz overgrowth and a porosity originated from different processes, initially by dissolution and later by partial filling and fracturing. Features like the presence of floating grains in the syntaxial cement, the transitional interpenetrative contact between the silica-rich cement and grains as well as the intense fracture porosity are strong indications that the cement has been formed by dissolution and reprecipitation of quartz from the framework under the effect of thermal expansion followed by rapid contraction. The increase of the silica-rich cement towards the dyke in association with the orthogonal disposition of the columns relative to dyke walls are indicative that the igneous body may represent the main heat source for the interstitial aqueous solutions previously existing in the sediments. At macroscopic scale, the increasing of internal tensions in the sandstones is responsible for the nucleation of polygons, leading to the individualization of prisms, which are interconnected by a system of joints, formed firstly on isotherm surfaces of low temperature and later on successive adjacent planes towards the dyke heat source.

Morphological aspects of the mid-palatal suture in the human foetus: A light and scanning electron microscopy study

Morphological features of the mid-palatal suture were studied in human foetuses from 4 to 9 months of intra-uterine life. The foetuses were divided into three age groups, GI (16-23 weeks), GII (24-31 weeks) and GIII (32-39 weeks). The mid-palatal suture in GI foetuses is rectilineal in form with a wide space between the palatal processes of the maxilla. The suture has a sinuous nature in GII and GIII foetuses due to growth of the bone processes crossing the mid-line. A wide zone of cellular proliferation observed in GI narrows in GII and GIII foetuses. The imbricating nature of the suture in GII and GIII is caused by bone growth adjacent to the mid-palatal suture. Sharpey's fibres, emerging from the bone processes, run to the median region of the mid-palatal suture and are observed from GI foetuses onwards. The collagen fibres of the mid-palatal suture are orientated transversely under the oral epithelium and exhibit a regular meshwork with a predominance of sagittal fibres in the median region of the suture. These fibres are orientated transversely and obliquely at the junction with the nasal septum.