Ontology-based Search Algorithms over Large-Scale Unstructured Peer-to-Peer Networks

Peer-to-Peer(P2P) systems have emerged as a promising paradigm to structure large scale distributed systems. They provide a robust, scalable and decentralized way to share and publish data.The unstructured P2P systems have gained much popularity in recent years for their wide applicability and simplicity. However efficient resource discovery remains a fundamental challenge for unstructured P2P networks due to the lack of a network structure. To effectively harness the power of unstructured P2P systems, the challenges in distributed knowledge management and information search need to be overcome. Current attempts to solve the problems pertaining to knowledge management and search have focused on simple term based routing indices and keyword search queries. Many P2P resource discovery applications will require more complex query functionality, as users will publish semantically rich data and need efficiently content location algorithms that find target content at moderate cost. Therefore, effective knowledge and data management techniques and search tools for information retrieval are imperative and lasting. In my dissertation, I present a suite of protocols that assist in efficient content location and knowledge management in unstructured Peer-to-Peer overlays. The basis of these schemes is their ability to learn from past peer interactions and increasing their performance with time.My work aims to provide effective and bandwidth-efficient searching and data sharing in unstructured P2P environments. A suite of algorithms which provide peers in unstructured P2P overlays with the state necessary in order to efficiently locate, disseminate and replicate objects is presented. Also, Existing approaches to federated search are adapted and new methods are developed for semantic knowledge representation, resource selection, and knowledge evolution for efficient search in dynamic and distributed P2P network environments. Furthermore,autonomous and decentralized algorithms that reorganizes an unstructured network topology into a one with desired search-enhancing properties are proposed in a network evolution model to facilitate effective and efficient semantic search in dynamic environments

GENOME WIDE ASSOCIATION STUDY TO IDENTIFY SINGLE NUCLEOTIDE POLYMORPHISM MARKERS FOR FE, ZN, AND SE CONCENTRATION IN FIELD PEA SEEDS

Micronutrient concentration is an important component of crop quality. Iron (Fe), zinc (Zn) and selenium (Se) are essential micronutrients for human health. Previous studies indicated substantial variation in micronutrient concentration in field pea (Pisum sativum L.). The objective of the current research was to evaluate a diverse pea panel for Fe, Zn, and Se concentration, and to identify associated single nucleotide polymorphism (SNP) markers using genome wide association study (GWAS). One hundred and seventy seven diverse pea accessions were assessed for Fe, Zn, and Se concentration from five location-years (2013 Saskatoon, 2014 Fargo, 2015 Saskatoon, 2016 Saskatoon and 2016 Rosthern) using atomic absorption spectroscopy. Accessions differed significantly for Fe and Zn in all location-years, but not for Se (P ≤ 0.05). Year and location effects were significant for all three micronutrients. Mean concentration in the five location-year combined analysis were 50.46, 29.49, and 0.95, and the concentration (μg/g) ranged from 29.22 to 90.53, 12.83 to 51.47 and 0.06 to 8.75 in the ground whole pea seeds for Fe, Zn, and Se, respectively. Concentration of Fe, Zn, and Se were significantly correlated (P ≤ 0.05) between each location with the exception of Se concentration between Fargo and Rosthern. Significant correlations were observed in all the location-years between Zn and Fe concentration (P ≤ 0.05). Se significantly correlated with Fe in all the location years, except 2016 Rosthern (P ≤ 0.05). The correlation between Se and Zn was only significant in 2014 Fargo and 2016 Saskatoon (P ≤ 0.05). Fe and Zn concentration showed significant positive correlations (P ≤ 0.05) with lodging and day to maturity (DTM), but not Se. In general, yield negatively correlated with Fe, Zn, and Se. The pea panel accessions clustered into nine major groups which could be considered consistent with the geographic origin of the accessions. Genotypic data generated from genotyping-by-sequencing were used in genome wide association study (GWAS) to identify significant SNP markers associated with Fe, Zn, and Se concentration. After Bonferroni correction, three significant markers for Fe concentration and seven significant markers for Zn concentration (P ≤ 0.05, -log10 P value ≥ 5.46) were identified. Five markers for Fe, seven markers for Zn and four markers for Se (including few less significant markers) were validated on a pea recombinant inbred line population; PR-07 (Carrera × CDC Striker). The marker Sc1512_36017 co-localized with Sc11336_48840 on LGIIIb which was a flanking marker of quantitative trait loci (QTL) for seed Zn concentration. The markers identified from the present study can be used in marker assisted selection (MAS) in pea breeding to develop new varieties with high Fe, Zn, and Se concentration

The orientation of Tribolium castaneum adults in the presence of aggregation pheromone 4,8-Dimethyldecanal and food oils

Monitoring of Tribolium castaneum, the red flour beetle, involves the use of aggregation pheromone 4,8- dimethyldecanal (4,8 DMD) and kairomones such as cereal oils. Despite their present use, certain information which maximizes the efficacy of these compounds is still lacking. These experiments tested the effects of distance from the pheromone and edible oils on the orientation of T. castaneum adults. The movement of adults toward the aggregation pheromone was determined by changing the distance from the pheromone or the air flow. The adults released inside a glass apparatus tested their orientation either toward the food oils or the empty vial. The maximum trap catch was recorded at distances up to 60 cm from the pheromone and with the presence of air flow. The oils having botanical origin successfully attracted adults than those of animal origin. It is concluded that the orientation of T. castaneum adults varies with the distance from pheromone, air flow and the nature of food oil.Monitoring of Tribolium castaneum, the red flour beetle, involves the use of aggregation pheromone 4,8- dimethyldecanal (4,8 DMD) and kairomones such as cereal oils. Despite their present use, certain information which maximizes the efficacy of these compounds is still lacking. These experiments tested the effects of distance from the pheromone and edible oils on the orientation of T. castaneum adults. The movement of adults toward the aggregation pheromone was determined by changing the distance from the pheromone or the air flow. The adults released inside a glass apparatus tested their orientation either toward the food oils or the empty vial. The maximum trap catch was recorded at distances up to 60 cm from the pheromone and with the presence of air flow. The oils having botanical origin successfully attracted adults than those of animal origin. It is concluded that the orientation of T. castaneum adults varies with the distance from pheromone, air flow and the nature of food oil

Molecular basis of viroid RNA-templated transcription

Transcription is a fundamental process catalyzed by DNA-dependent RNA polymerases (DdRPs). Interestingly, some DdRPs can use both DNA and RNA as templates for transcription. This RNA-dependent RNA polymerase (RdRP) activity of DdRPs is used by RNA-based pathogens such as viroids and hepatitis delta virus for replication. In addition, RdRP activity of DdRPs widely occurs in various organisms to regulate gene transcription. Despite the importance of this intrinsic RdRP activity of DdRPs, associated factors and mechanisms are in their infancy stage. We employed potato spindle tuber viroid (PSTVd) as a model to study RNA-templated transcription. Here, we present evidence showing that circular PSTVd templates are critical for the synthesis of longer-than-unit-length (-) strand products. Further, we show transcription factor IIS is dispensable for PSTVd replication supporting de novo transcription on PSTVd RNA templates. The absence of canonical general transcription factor, TFIIS from PSTVd-templated transcription complex led to the hypothesis that RNA-templated transcription has a distinct organization on the RNA template. To test this hypothesis, we used our well-established in vitro transcription (IVT) system and demonstrated that RNA polymerase II (Pol II) accepts minus-strand for transcription. In addition, transcription factor TFIIIA-7ZF is needed to aid Pol II transcription activity. Further analyses of the critical zinc finger domains in TFIIIA-7ZF revealed that the first three zinc finger domains are pivotal for template binding. Notably, we identified a remodeled Pol II complex for viroid transcription that is missing Rpb4, Rpb5, Rpb6, Rpb7, and Rpb9. General transcription factors for DNA-templated transcription are also absent in the transcription complex on the RNA template. This remodeled Pol II complex still possesses the transcription activity on PSTVd RNA template. Collectively, our data illustrate a distinct organization of Pol II complex on viroid RNA templates, providing new insights into viroid replication, the evolution of transcription machinery, as well as the mechanism of RNA-templated transcription

Development of a Three-Dimensional Trap for Single-Molecule Studies with a Four-Focus Confocal Fluorescence Microscope

This dissertation presents the development of an instrument based on a confocal fluorescence microscope for feedback-driven trapping of a single molecule or nanoparticle in three-dimensions as it undergoes Brownian diffusion within an aqueous medium. Such trapping enables prolonged observation of a molecule while untethered and free from collisions with surfaces, which is needed to improve various studies, such as investigations of protein folding dynamics, molecular heterogeneities, and interactions. In the experiment, a dilute solution (~100 pM) of fluorescent nano-objects is inserted into a microfluidic device, which achieves trapping by control of electroosmotic flows in two crossed channels. The geometry, which is designed using COMSOL Multiphysics, funnels the flows to achieve sufficient electroosmotic speed to counteract Brownian diffusion while maintaining a 4:1 width-to-depth for wide-angle light collection by the microscope objective from the center of the crossing region. A fluorescence excitation volume centered at this point is defined by four overlapping focused laser beams, each with ~0.5 μm beam waist but with centers offset in a tetrahedral arrangement. The beams are derived from a mode-locked laser using a series of beam splitters with the pulses in each beam delayed to provide pulse-interleaved excitation at 304 MHz. Fluorescence is collected through a pinhole and split to two single-photon detectors, which provide signals for an FPGA (Field Programmable Gate Array) for time-gated counting into four channels synchronous with the pulses in each of the laser beams. The FPGA also bins the counts and applies an algorithm to estimate the direction of the position offset of the nano-object and to adjust four voltages. These are applied at the four fluid inlets of the microfluidic cross-channel to electroosmotically drive the fluid to keep the nano-object at the midpoint of the four foci. Movies of camera imaging of trapped nano-objects were acquired. Results show trapping of 40 nm FluoSpheres for ~4 minutes, 20 nm FluoSpheres for ~25 seconds, and 5 nm protein molecules of Streptavidin-Alexa Fluor™ 647 for ~1.5 seconds. In addition, Maximum Likelihood Estimation of positions from binned photons was conducted for the FluoSphere experiments to estimate effective spring constants of the trap

The Gravity of Entrepreneurs’ Network Ties on the growth of the Business in Sri Lanka

Using the business performances of the firm we investigated how network ties (NT) interfere to obtain business growth in Sri Lankan context. As NT consist of two constructs which are social NT and business NT, this study aims to what extent both constructs engaged to the growth of the business in distinctly. It was mainly hypothesized that entrepreneurs who have high NT could perform more than others who engaged with lack of NT in same context.  Finally results confirmed that NT has a positive impact on business growth. However, results indicated that business NT has significant influence on business growth than social NT. The results of the study have important implications to the existing entrepreneurs, potential entrepreneurs, investors, researchers, consultants and policy makers. Keywords: Network Ties, Social Network Ties, Business Network Ties, Business Performanc

Effects of culture conditions on growth and survival of Poecilia sphenops and Poecilia reticulata

Poecilia sphenops and P. reticulata are considered as two most popular and high demanding freshwater ornamental fish species globally. The effects of feeding frequency, feed protein level, photoperiod and salinity on growth and survival of these species and the effect of sex ratio on fecundity were studied under laboratory conditions from January to December 2016. Although there was no any significant impact of feeding frequency on growth and survival of these species, feed protein content affected significantly on their growth. Fry fed with newly hatched Artemia, commercial larval feeds and Chlorella sp. showed no significant impact on growth. Poecilia sphenops and P. reticulata could tolerate salinity up to 10 and 25 ppt, respectively. Fish exposed to 8 hrs photoperiod reported significantly lower growth than those who were exposed to 12 and 24 hrs photoperiods. The ideal female: male sex ratio for commercial stocking of P. sphenops and P. reticulata was 3:2

Mineral trioxide aggregate repair of lateral root perforation using intentiional replantation and bone grafting

Root perforation is a significant complication during root canal treatment. Root perforation can result in loss of integrity of the root structure and severe periodontal and bone defect. Repair of lateral root perforation presents a clinical challenge to the operator. This report is of root perforation during post space preparation in a right maxillary central incisor that has caused an extensive periodontal lesion. Since the bone lesion was large and unreachable from either a coronal access cavity or buccal surgical flap, a combination of mineral trioxide aggregate sealing, bone grafting, and intentional replantation was used as the method of treatment. The patient’s symptoms ceased and the existing lesions resolved during the 5-year follow-up.published_or_final_versio

COVID-19 Outbreak and Industry Reactions: Evidence from Colombo Stock Exchange

Moving along history, it can be identified that the human race has experienced many types of challenges which did have the capacity to decide human existence or extinction from the beginning. Some of these challenges were created by humans by themselves like world wars and some were created by natural forces like natural disasters and deadly viruses.Recently COVID-19 has taken place as a rapidly spreading virus by causing more than two million deaths and more than 95 million cases around the world as being the sixth global pandemic creating considerable influence to different industries such as agriculture, health and transportation in the world. The propose of this study is to identify the impact of COVID-19 on the performance of the industries in Sri Lanka. Using the two events and the event study methodology it is found that industry groups such as automobiles, materials, health care and equipment, household and personal care products are the significantly positively affected industries where industries like insurance and transportation have been negatively affected in Sri Lanka. As per the real business-cycle theory these fluctuations in the industries consider as business cycle fluctuations and the efficient response to exogenous changes in the real economic environment. Hence this impact does not last long, investors and the government can recover quickly with the implementation of effective monetary policies and investment diversification

根の生育の柔軟性とリン再転流によるイネのリン欠乏適応機構

内容の要約広島大学(Hiroshima University)博士(農学)Doctor of Agriculturedoctora