Exploitable socio-economic benefits of mangrove oyster culture to the people of Niger Delta

The Niger Delta, a 30,000 km2 wetland of global ecological significance is located at the southernmost part of Nigeria. The Delta is dissected by a dense network of rivers and creeks of saline and freshwater surface bodies. The brackish water (saline) sector consists of estuaries and intertidal mangrove swamps; the total brackish water area for the Niger Delta estimated at about 7,415 km2. The mangrove oysters grow chiefly in brackish water creeks of Bayelsa, Delta and Rivers States, found attached to the aerial roots of the mangrove Rhizophora racemosa (Red mangrove). Mangroves are salt-tolerant evergreen forests found along sheltered coastlines, shallow-water lagoons, estuaries, rivers or deltas; stands stretching 30-40 km inland with an estimated area of 997, 700 ha in Nigeria. Aquaculture has an important role in the development of many national economies and plays a key role in rural development. The abundance of a natural population of mangrove oysters in the Niger Delta makes seed collectors and growing easier and inexpensive. The culture of mangrove oysters by the locals will contribute significantly to economic growth, increases income and food security, efficient utilization of surplus rural labour and reduced social problems, poverty alleviation, and social stability. This paper enumerates the culture and socio-economic benefits derivable from the practice of aquaculture through the sustainable culture of the native mangrove oysters

Review of high voltage direct current cables

Increased renewable energy integration and international power trades have led to the construction and development of new HVDC transmission systems. HVDC cables, in particular, play an important role in undersea power transmission and offshore renewable energy integration having lower losses and higher reliability. In this paper, the current commercial feasibility of HVDC cables and the development of different types of HVDC cables and accessories are reviewed. The non-uniform electric field distribution caused by the applied voltage, temperature dependent conductivity, and space charge accumulation is briefly discussed. Current research in HVDC cable for higher operation voltage level and larger power capacity is also reviewed with specific focus on the methodologies of space charge suppression for XLPE extruded cable

Citrate and malonate increase microbial activity and alter microbial community composition in uncontaminated and diesel-contaminated soil microcosms

Petroleum hydrocarbons (PHCs) are among the most prevalent sources of environmental contamination. It has been hypothesized that plant root exudation of low molecular weight organic acid anions (carboxylates) may aid degradation of PHCs by stimulating heterotrophic microbial activity. To test their potential implication for bioremediation, we applied two commonly exuded carboxylates (citrate and malonate) to uncontaminated and diesel-contaminated microcosms (10 000 mg kg−1; aged 40 days) and determined their impact on the microbial community and PHC degradation. Every 48 h for 18 days, soil received 5 µmol g−1 of (i) citrate, (ii) malonate, (iii) citrate + malonate or (iv) water. Microbial activity was measured daily as the flux of CO2. After 18 days, changes in the microbial community were assessed by a community-level physiological profile (CLPP) and 16S rRNA bacterial community profiles determined by denaturing gradient gel electrophoresis (DGGE). Saturated PHCs remaining in the soil were assessed by gas chromatography–mass spectrometry (GC-MS). Cumulative soil respiration increased 4- to 6-fold with the addition of carboxylates, while diesel contamination resulted in a small, but similar, increase across all carboxylate treatments. The addition of carboxylates resulted in distinct changes to the microbial community in both contaminated and uncontaminated soils but only a small increase in the biodegradation of saturated PHCs as measured by the n-C17 : pristane biomarker. We conclude that while the addition of citrate and malonate had little direct effect on the biodegradation of saturated hydrocarbons present in diesel, their effect on the microbial community leads us to suggest further studies using a variety of soils and organic acids, and linked to in situ studies of plants, to investigate the role of carboxylates in microbial community dynamics

Low molecular weight organic anions (carboxylates) increase microbial activity and alter microbial community composition in uncontaminated and diesel contaminated soil

Petroleum hydrocarbons (PHCs) are among the most prevalent sources of environmental contamination. It has been hypothesized that plant root exudation of low molecular weight organic acid anions (carboxylates) may aid degradation of PHCs by stimulating heterotrophic microbial activity. We, therefore, applied two commonly-exuded carboxylates (citrate and malonate) to uncontaminated and diesel contaminated microcosms (10,000 mg kg–1; aged 40 days) to determine their impact on the microbial community and PHC degradation. Every 48 hours for 18 days, soil received 5 μmol g–1 of i) citrate, ii) malonate, iii) citrate + malonate or iv) water. Microbial activity was measured daily as the flux of CO2. After 18 days, changes in the microbial community were assessed by community level physiological profiles and 16S rRNA bacterial community profiles determined by denaturing gradient gel electrophoresis. Saturated PHCs remaining in the soil were assessed by GCMS. Cumulative soil respiration increased four- to six-fold with the addition of carboxylates, while diesel contamination resulted in a small, but similar, increase across all carboxylate treatments. The addition of carboxylates resulted in distinct changes to the microbial community, but only a small decrease in the n-C17: pristane biomarker. We conclude that carboxylate addition can increase microbial activity and modify the microbial community in both uncontaminated and diesel-contaminated soils. The impact of these changes on PHC biodegradation and rhizosphere processes, more generally, merits further research

Optimization in Genetically Evolved Fuzzy Cognitive Maps Supporting Decision-Making: The Limit Cycle Case

This paper presents the dynamic behavior of a hybrid system comprising Fuzzy Cognitive Maps and Genetic Algorithms, and focuses on the behavior observed when the system reaches equilibrium at fixed points or limit cycle. More specifically, the present works examines the theoretical background of the equilibrium and limit cycle behaviors and proposes a defuzzification method to handle the latter case. The proposed method calculates the mean value of a limit cycle and uses this value in the defuzzification process along with a confidence rate, which indicates the reliability of the results

Optimization in Genetically Evolved Fuzzy Cognitive Maps Supporting Decision-Making: The Limit Cycle Case

This paper presents the dynamic behavior of a hybrid system comprising Fuzzy Cognitive Maps and Genetic Algorithms, and focuses on the behavior observed when the system reaches equilibrium at fixed points or limit cycle. More specifically, the present works examines the theoretical background of the equilibrium and limit cycle behaviors and proposes a defuzzification method to handle the latter case. The proposed method calculates the mean value of a limit cycle and uses this value in the defuzzification process along with a confidence rate, which indicates the reliability of the results

Design data for footwear: sweating distribution on the human foot

Purpose – The purpose of this paper is to provide footwear designers, manikin builders and thermo-physiological modellers with sweat distribution information for the human foot. Design/methodology/approach – Independent research from two laboratories, using different techniques, is brought together to describe sweat production of the foot. In total, 32 individuals were studied. One laboratory used running at two intensities in males and females, and measured sweat with absorbents placed inside the shoe. The other used ventilated sweat capsules on a passive, nude foot, with sweating evaluated during passive heating and incremental exercise to fatigue. Findings – Results from both laboratories are in agreement. Males secreted more than twice the volume of sweat produced by the females (p<0.01) at the same relative work rate. Both genders demonstrated a non-uniform sweat distribution, though this was less variable in females. Highest local sweat rates were observed from the medial ankles (p<0.01). The dorsal foot sweated substantially more than the plantar (sole) areas (p<0.01). Sweating on the plantar side of the foot was uniform. Wearing shoes limited the increase in sweat production with increasing load, while the sweat rate of uncovered feet kept increasing with work and thermal load. Practical implications – The observed variation in sweat rate across the foot shows that footwear design should follow the body mapping principle. Fabrics and materials with different properties can be used to improve comfort if applied to different foot surfaces. The data also demonstrate that foot models, whether physical (manikins) or mathematical, need to incorporate the observed variation across the foot to provide realistic simulation/testing of footwear

Identifying the quark content of the isoscalar scalar mesons f_0(980), f_0(1370), and f_0(1500) from weak and electromagnetic processes

The assignments of the isoscalar scalar mesons f0(980), f0(1370), and f0(1500) in terms of their qqbar substructure is still a matter of heated dispute. Here we employ the weak and electromagnetic decays D(s)(+) to f0+pi(+) and f0 two-photon decays, respectively, to identify the f0(980) and f0(1500) as mostly ssbar, and the f0(1370) as dominantly nonstrange, in agreement with previous work. The two-photon decays can be satisfactorily described with quark as well as with meson loops, though the latter ones provide a less model-dependent and more quantitative description.Comment: v1, 15 pages, plain LaTeX, 1 eps figure. v2, 18 pages, plain LaTeX (figure included). More discussion, especially on the f0(1370) and its empirical two-photon widt

Chemical assays and chromatographíc analysis from tannins contents in Gomidesia palustris (DC.) Kausel (Myrtaceae)

Gomidesia palustris (DC.) Kausel é uma planta pertencente à família Myrtaceae, de ampla ocorrência na região sul do Brasil, conhecida popularmente como "pitangueira-do-mato" ou "guamirim". Não tendo sido encontradas referências a estudos anteriores, as folhas e os frutos foram analisados quanto à composição química. Os testes preliminares indicaram teor elevado de taninos. Os ensaios químicos e a análise cromatográfica indicaram a presença de taninos hidrolisáveis, com a predominância de taninos elágicos. Para a quantificação desse tipo de composto foi utilizado, com algumas adaptações, o método de hemoanálise com doseamento espectrofotométrico da hemoglobina residual, após precipitação dos taninos, sendo encontrado um valor médio de 12,71% de compostos tanantes nas folhas. Através de processos cromatográficos, foram isolados o ácido elágico e o ácido gálico.Gomidesia palustris (DC.) Kausel (Myrtaceae) is an evergreen tree widely spread in southern Brazil and surrounding regions, commonly known as "pitangueira-do-mato" or "guamirim". There is no former reference to the chemical studies of this species. Preliminary tests and further chemical assays and chromatographic analysís detected high tannins contents in the leaves, chiefly hydrolisable tannins with predominance of ellagitannins. Ellagic acid and gallic acid were isolated by chromatographic methods. The content of the tannins was determined by spectrophotometric haemoanalysis after a partial precipitation with tannins (modified Bate-Smith's method). A mean content of 12,71% was found in the leaves

Optimized loading of an optical dipole trap for the production of Chromium BECs

We report on a strategy to maximize the number of chromium atoms transferred from a magneto-optical trap into an optical trap through accumulation in metastable states via strong optical pumping. We analyse how the number of atoms in a chromium Bose Einstein condensate can be raised by a proper handling of the metastable state populations. Four laser diodes have been implemented to address the four levels that are populated during the MOT phase. The individual importance of each state is specified. To stabilize two of our laser diode, we have developed a simple ultrastable passive reference cavity whose long term stability is better than 1 MHz