First and subsequent return stroke properties of cloud-to-ground lightning

Lightning properties obtained by a network of magnetic direction finders and by electric field measurements for distances from 50 to 500 km are compared for three summer thunderstorms in Sweden. The data from direct field recordings indicate 31, 17, and 26 pcts. of negative subsequent return strokes with peak current (as inferred from the peak electric field) higher than the first. Electric fields from first strokes are compared with normalized amplitudes registered by the magnetic direction finding system. The efficiency of detection by the magnetic direction finding system is discussed in terms of the percentage of lightning flashes observed by electric field measurements that are not localized. Statistics of the number of strokes per flash and the interstroke time intervals are presented

Isolation and Characterisation of Genes Expressed in Zygotic Embryos and Suspension Cultures of Oil Palm (Elaeis Guineensis Jacq.)

The bottleneck of the current oil palm tissue culture technique is the low rate of embryogenesis and the development of viable embryoid lines. Therefore, it is vital to increase the efficiency of callusing, embryogenesis, germination and proliferation of embryoids so that the number of subcultures per line can be reduced without effecting the number of shoots produced in-vitro. Thus, it is necessary to elucidate and understand the molecular processes that are involved during somatic embryogenesis of oil palm particularly those involved in specifying embryogenic competence. Based on the role of cell division cycle (cdc/cdk) genes and cyclins in cell division cycle control of other eukaryotes, it is likely that cyclins are also partially involved in the regulation of somatic embryogenesis. Hence, an attempt to isolate cyclin genes from the oil palm zygotic embryo cDNA library was made using heterologous cyclin cDNA probes from Arabidopsis. 32 putative clones designated as OPZE, were isolated from screening. A preliminary characterisation was carried out on these clones in order to identify clones with sequences related to the cell division cycle. This was achieved by hybridising the peR amplified OPZE clones with amplified cDNA from suspension cultures and mature leaves separately. The OPZE clones were categorised into 3 subpopulations according to their tissue-specific expression pattern: a, b and c. Randomly selected clones from these subpopulations were sequenced partially and used for sequence homology searches using DNA sequence databases. Most clones did not have any significant homology to any known sequences in the database, thus they were designated as novel clones. Three clones OPZEJA, OPZE3A and OPZE5A that had significant homology to oleo sin, calmodulin and tumour suppressor protein respectively were selected for northern analysis. From the northern analysis studies, it was found that OPZEJA (oleosin) is zygotic embryo specific and both OPZE3A and OPZE5A are ubiquitously expressed in all evaluated tissues. In order to complement this study, a partial length homeobox gene, OPHbJ (KnottedJ -like) from oil palm was isolated and was found to be expressed specifically in meristematic tissues. However, the specific functions of these genes during oil palm embryogenesis are still unknown

ON SIMPLE BUT HARD RANDOM INSTANCES OF PROPOSITIONAL THEORIES AND LOGIC PROGRAMS

In the last decade, Answer Set Programming (ASP) and Satisfiability (SAT) have been used to solve combinatorial search problems and practical applications in which they arise. In each of these formalisms, a tool called a solver is used to solve problems. A solver takes as input a specification of the problem – a logic program in the case of ASP, and a CNF theory for SAT – and produces as output a solution to the problem. Designing fast solvers is important for the success of this general-purpose approach to solving search problems. Classes of instances that pose challenges to solvers can help in this task. In this dissertation we create challenging yet simple benchmarks for existing solvers in ASP and SAT.We do so by providing models of simple logic programs as well as models of simple CNF theories. We then randomly generate logic programs as well as CNF theories from these models. Our experimental results show that computing answer sets of random logic programs as well as models of random CNF theories with carefully chosen parameters is hard for existing solvers. We generate random logic programs with 2-literals, and our experiments show that it is hard for ASP solvers to obtain answer sets of purely negative and constraint-free programs, indicating the importance of these programs in the development of ASP solvers. An easy-hard-easy pattern emerges as we compute the average number of choice points generated by ASP solvers on randomly generated 2-literal programs with an increasing number of rules. We provide an explanation for the emergence of this pattern in these programs. We also theoretically study the probability of existence of an answer set for sparse and dense 2-literal programs. We consider simple classes of mixed Horn formulas with purely positive 2- literal clauses and purely negated Horn clauses. First we consider a class of mixed Horn formulas wherein each formula has m 2-literal clauses and k-literal negated Horn clauses. We show that formulas that are generated from the phase transition region of this class are hard for complete SAT solvers. The second class of Mixed Horn Formulas we consider are obtained from completion of a certain class of random logic programs. We show the appearance of an easy-hard-easy pattern as we generate formulas from this class with increasing numbers of clauses, and that the formulas generated in the hard region can be used as benchmarks for testing incomplete SAT solvers

Science camp fundraiser kumpul dana bantu kanak-kanak kurang bernasib baik

SERDANG,10 Dis – Pelajar dan kakitangan Jabatan Biologi Sel dan Molekul(BSM), Fakulti Bioteknologi dan Sains Biomolekul (FBSB), Universiti Putra Malaysia (UPM) dengan kerjasama Pertubuhan Bukan Kerajaan (NGO), Tech Outreach Malaysia menganjurkan program komuniti ‘Science Camp Fundraiser’ bertujuan mengumpul dana bagi keperluan kanak-kanak yang kurang bernasib bai

Molecular docking interaction of mycobacterium tuberculosis lipb enzyme with isoniazid, pyrazinamide and a structurally altered drug 2, 6 dimethoxyisonicotinohydrazide

Tuberculosis is an infectious airborne disease caused by a bacterial infection that affects the lungs and other parts of the body. Vaccination against tuberculosis is available but proved to be unsuccessful against emerging multi drug and extensive drug resistant bacterial strains. This in turn raises the pressure to speed up the research on developing new and more efficient anti-tuberculosis drugs. Lipoate biosynthesis protein B (LipB) is found to play vital role in the lipoylation process in Mycobacterium tuberculosis and thus making it a very promising drug target. The existing first line drugs such as Isoniazid, Pyrazinamide and Rifampicin etc shows only profound binding affinity with this target protein. Therefore, new or modified drugs with better docking approach that exhibit a closer and stronger binding affinity is essential. This current study opens up a novel approach towards anti-tuberculosis agents by determining drugs that share similar structures with some of the best available first line drug and also happen to possess better binding affinity. In this article, a computational method by which, pristine as well certain first line and structurally modified drugs were docked with the LipB protein target; where, structurally modified 2, 6 Dimethoxyisonicotinohydrazide show superior target docking

Combustion, performance and emissions characteristics of compression-ignition engines fuelled by sustainable fuels

PhDInternal combustion engines are approaching their theoretical maximum efficiency, which could indicate limited future technological improvements in performance and exhaust emissions with standard fuels. In addition, fossil fuel dependence can only be reduced by implementing appropriate renewable fuel sources. The experimental investigation in this work only concerns the compression-ignition (CI) engine combustion process both in normal operation and “dual-fuel” operation. The dual-fuel mode allows low-cetane number fuel to be used in CI engines, with a “pilot” fuel spray injection of high-cetane number fuel to provide ignition. Initially, rapeseed methyl ester (RME) and two water-in-RME emulsions were compared with normal diesel fuel during normal operation. Neat RME generally performed similarly to diesel fuel, while giving higher specific fuel consumption (SFC) levels. Both water- in-RME emulsions performed fairly similarly to neat RME. This suggests that the cooling effect of water vapourisation was a negligible factor throughout the operating range. Natural gas dual-fuel operation reduced NOx at certain conditions and overall CO2 emissions while thermal efficiencies were maintained compared with normal operation. However, significantly higher unburnt hydrocarbons (HC) and CO emissions were recorded at low and intermediate engine loads. For the emulsified pilot fuels, better fuel-air mixing (possibly as a result of “microexplosions”) increased NOx after an equivalence ratio of about 0.6. Hydrogen dual-fuel operation generally increased NOx emissions while CO2 emissions were reduced compared with normal operation. Thermal efficiencies remained comparable for all pilot fuels. NOx emissions in the emulsified fuel cases were generally comparable to the neat RME pilot. Lower volumetric efficiency was also recorded, while power output was limited to maintain engine stability and avoid abnormal combustion caused by excessively high pressure-rise rates (called “hydrogen knock”). Overall, significant optimisation is needed to improve combustion efficiency at low and intermediate engine loads during dual-fuel CI engine operation. As these engines are designed specifically for liquid fuels, substantial engine customisation or even complete redesign (particularly in the fuel supply system) is needed to improve the combustion quality on a scale larger than that seen in this work

A putative proline-rich protein of B. napus

Proline-rich proteins are among the major protein components of plant cell walls. So far, two different proline-rich cell wall proteins have been described in Brassica napus. This paper reports a study on expression and sequence analysis of a novel class of a proline-rich putative protein, tentatively designated Ae4. The largest ORF of Ae4 encodes 166 amino acid residues without the start and stop codons. Ae4 is a partial length cDNA. The Ae4 gene expression was investigated and the results demonstrate that it accumulates in all vegetative tissues tested as well as in the embryogenic culture of Brassica napus. However, expression of Ae4 was undetectable in the non-embryogenic and cytokinin-treated embryogenic tissues. These results indicate that the Ae4 gene might play a role in somatic embryo formation

Vacuum polarization on three-dimensional anti-de Sitter space-time with Robin boundary conditions

We study a quantum scalar field, with general mass and coupling to the scalar curvature, propagating on three-dimensional global anti-de Sitter space-time. We determine the vacuum and thermal expectation values of the square of the field, also known as the vacuum polarisation (VP). We consider values of the scalar field mass and coupling for which there is a choice of boundary conditions giving well-posed classical dynamics. We apply Dirichlet, Neumann and Robin (mixed) boundary conditions to the field at the space-time boundary. We find finite values of the VP when the parameter governing the Robin boundary conditions is below a certain critical value. For all couplings, the vacuum expectation values of the VP with either Neumann or Dirichlet boundary conditions are constant and respect the maximal symmetry of the background space-time. However, this is not the case for Robin boundary conditions, when both the vacuum and thermal expectation values depend on the space-time location. At the space-time boundary, we find that both the vacuum and thermal expectation values of the VP with Robin boundary conditions converge to the result when Neumann boundary conditions are applied, except in the case of Dirichlet boundary conditions.Comment: 23 pages, 10 figure

Removal of Congo Red from Aqueous Solution by Waste Banana Pith

The ability of waste banana pith to remove Congo red from aqueous solution was investigated. Various parameters such as initial dye concentration, contact time, adsorbent dosage and pH effect were studied. The adsorption rate constant was found to be 1 X 10.1 min'} at 50 mg I-I dye concentration. Above 92% removal was observed in the pH range 2-11. The removal of dye by banana pith is mostly due to chemisorption