Nitrate supply routes and impact of internal cycling in the North Atlantic Ocean inferred from nitrate isotopic composition

In this study we report full‐depth water column profiles for nitrogen and oxygen isotopic composition (δ15N and δ18O) of nitrate (NO3‐) during the GEOTRACES GA01 cruise (2014). This transect intersects the double gyre system of the subtropical and subpolar regions of the North Atlantic separated by a strong transition zone, the North Atlantic Current. The distribution of NO3‐ δ15N and δ18O shows that assimilation by phytoplankton is the main process controlling the NO3‐ isotopic composition in the upper 150 m, with values increasing in a NO3‐ δ18O versus δ15N space along a line with a slope of one towards the surface. In the subpolar gyre, a single relationship between the degree of NO3‐ consumption and residual NO3‐ δ15N supports the view that NO3‐ is supplied via Ekman upwelling and deep winter convection, and progressively consumed during the Ekman transport of surface water southward. The co‐occurrence of partial NO3‐ assimilation and nitrification in the deep mixed layer of the subpolar gyre elevates subsurface NO3‐ δ18O in comparison to deep oceanic values. This signal propagates through isopycnal exchanges to greater depths at lower latitudes. With recirculation in the subtropical gyre, cycles of quantitative consumption‐nitrification progressively decrease subsurface NO3‐ δ18O toward the δ18O of regenerated NO3‐. The low NO3‐ δ15N observed south of the Subarctic Front is mostly explained by N2 fixation, although a contribution from the Mediterranean outflow is required to explain the lower NO3‐ δ15N signal observed between 600 and 1500 m depth close to the Iberian margin

Sustainable development through proper land utilization Case study Ratnapura, Sri Lanka

Since the land is a scarce resource, the utilization of land effectively would be directly affected to thesustainable development of any country. A proper system ofland uti Iization is very essential especiallyfor a country like Sri Lanka which is very small in size and the majority of the people are dependingon the land related activities such as farming, grazing etc. as their major source of income. Unfortunately,land is in the state of under utilization in Sri Lanka. This paper attempts to study the importance of theeffective land utilization using Geographical Information Systems (GIS) for the sustainable development.The study was mainly based on the data gathered from Ratnapura Divisional Secretary area, Thearea is consisting with natural vegetations such as forests, shrubs. and man -rnade cultivation such astea, rubber, paddy. Also the area has a high economic value and it is well known for natural disasterssuch as floods and earth slips. Primary data was collected using semi-structured questionnaires,interviewing people and relevant officers and field surveying using hand held Global Positioning System(GPS). The study supplemented with secondary data such as remote sensing satellite images, existingmaps. GIS technique was used for the data analyses.The study identified 4 major issues in the specified areaI. 20 % of the total area is under utilization2. 25 % of the total area is misused3. 05 % of the total area is over utilized4. Continuous loss of land due to the natural disastersAccording to the results, the land has not used effectively in the area. 45% of the area is not usedeffectively. Since the country is very small, proper land utilization is very important. The study suggestthat an immediate action should be taken to overcome the matter. And also it is very important to getthe active participation of the general public to stop the loss ofland due to natural disasters and forfuture decision making. 

Modeling the asymmetric evolution of a mouse and rat-specific microRNA gene cluster intron 10 of the Sfmbt2 gene

<p>Abstract</p> <p>Background</p> <p>The total number of miRNA genes in a genome, expression of which is responsible for the miRNA repertoire of an organism, is not precisely known. Moreover, the question of how new miRNA genes arise during evolution is incompletely understood. Recent data in humans and opossum indicate that retrotranspons of the class of short interspersed nuclear elements have contributed to the growth of microRNA gene clusters.</p> <p>Method</p> <p>We studied a large miRNA gene cluster in intron 10 of the mouse Sfmbt2 gene using bioinformatic tools.</p> <p>Results</p> <p>Mice and rats are unique to harbor a 55-65 Kb DNA sequence in intron 10 of the Sfmbt2 gene. This intronic region is rich in regularly repeated B1 retrotransposons together with inverted self-complementary CA/TG microsatellites. The smallest repeats unit, called MSHORT1 in the mouse, was duplicated 9 times in a tandem head-to-tail array to form 2.5 Kb MLONG1 units. The center of the mouse miRNA gene cluster consists of 13 copies of MLONG1. BLAST analysis of MSHORT1 in the mouse shows that the repeat unit is unique for intron 10 of the Sfmbt2 gene and suggest a dual phase model for growth of the miRNA gene cluster: arrangment of 10 MSHORT1 units into MLONG1 and further duplication of 13 head-to-tail MLONG1 units in the center of the miRNA gene cluster. Rats have a similar arrangment of repeat units in intron 10 of the Sfmbt2 gene. The discrepancy between 65 miRNA genes in the mouse cluster as compared to only 1 miRNA gene in the corresponding rat repeat cluster is ascribed to sequence differences between MSHORT1 and RSHORT1 that result in lateral-shifted, less-stable miRNA precursor hairpins for RSHORT1.</p> <p>Conclusion</p> <p>Our data provides new evidence for the emerging concept that lineage-specific retroposons have played an important role in the birth of new miRNA genes during evolution. The large difference in the number of miRNA genes in two closely related species (65 versus 1, mice versus rats) indicates that this species-specific evolution can be a rapid process.</p

Actual and perceived causes of flood risk: climate versus anthropogenic effects in a wet zone catchment in Sri Lanka

The Kalu Ganga Basin in Sri Lanka is generally flooded once a year. A network of low-lying lands acts as natural retention and storage that captures floodwater, minimizing damage. An increase in the flood frequency has been observed in recent years. It is commonly perceived that this increase is caused by a rise in the frequency and severity of ‘very wet’ precipitation events. We conclude that land-use changes may have played a larger role in generating floods

A lossless compression technique for Huffman-based differential encoding in IoT for smart agriculture

Agriculture faces several uncertain problems in terms of making the best use of its natural resources. As a result, and in light of the growing threat of changing weather conditions, we must closely track local soil conditions and meteorological data to expedite the adoption of culture-friendly decisions. In the Internet of Things (IoT) era, deploying Wireless Sensor Networks (WSN) as a low-cost remote monitoring and management system for these types of features is a viable choice. However, the WSN is hampered by the motes’ insufficient energy sources, which reduces the network’s overall lifespan. Each mote collects the tracked feature regularly and sends the data to the sink for further analysis. This method of transmitting large amounts of data requires the sensor node to use a lot of energy and a lot of network bandwidth. We propose a lightweight lossless compression algorithm based on Differential Encoding (DE) and Huffman techniques in this paper, which is especially useful for IoT sensor nodes that track environmental features, especially those with limited computing and memory resources. Rather than attempting to create novel ad hoc algorithms, we show that, given a general understanding of the features to be monitored, classical Huffman coding can be used to effectively represent the same features that measure at different times and locations. Even though the proposed system does not achieve the theoretical limit, results using temperature measurements show that it outperforms standard methods built specifically for WSNs