498 research outputs found
Digitization Methods of Grinding Pins for Technological Process Planning
The paper presents different techniques for digitizing grinding pins and discusses the use of digitalized pins and the results of measurements in technological process planning (TPP), focusing on the challenges of the digital era. It describes the potential of different measuring devices, taking into account the digitization of a real tool shape into virtual 2D and 3D models. The following methods for measuring grinding pins are presented in the study: contact and non-contact coordinate measurements – performed on coordinate measuring machines (CMM); optical measurements on microscopes (i.e. focus-variation technique); optical measurements using tool presetters; optical measurements with measuring arm; laser micrometer measurements; and laser triangulation sensor measurements. Moreover, the use of testers which are applied in contour measurements is analyzed. On the basis of the presented methods, taking into account their possibilities and limitations, we discuss how the obtained digital data can be used in the planning of technological processes.publishedVersio
Post-Disaster Housing Reconstruction in Sri Lanka: What Methodology?
Research methodology is the procedural framework within which the research is conducted. This includes the overall
approach to a problem that could be put into practice in a research process, from the theoretical underpinning to the
collection and analysis of data. Choice of methodology depends on the primary drivers: topic to be researched and the
specific research questions. Hence, methodological perspectives of managing stakeholder expectations of PDHR context
are composed of research philosophies, research strategy, research design, and research techniques. This research belonged
to social constructivism or interpretivism within a philosophical continuum. The nature of the study was more toward
subjectivism where human behavior favored voluntary stance. Ontological, methodological, epistemological, and axiological
positioning carried the characteristics of idealism, ideographic, anti-positivism, and value laden, respectively. Data collection
comprises two phases, preliminary and secondary. Exploratory interviews with construction experts in the United Kingdom
and Sri Lanka were carried out to refine the interview questions and identify the case studies. Case study interviews during
the secondary phase took place in Sri Lanka. Data collected at the preliminary stage were used to assess the attributes of
power, legitimacy/proximity, and urgency of stakeholders to the project using Stakeholder Circle™ software. Moreover,
the data collected at secondary phase via case studies will be analyzed with NVivo 8. This article aims to discuss these
methodological underpinnings in detail applied in a post-disaster housing reconstruction context in Sri Lanka
COMPOSITION, STRUCTURE AND ORGANIZATION OF MIXED-SPECIES BIRD FLOCKS IN WALAUWA TTA-WA TURANA SWAMP FOREST, KALUTARA DISTRICT, WESTERN PROVINCE OF SRI LANKA
Mixed- species foraging bird flocks in Walauwatta-Waturan Swamp Forest (WWSF) were studiedfor a period of six months from February to July in 2001. Field data was collected from 07:00 to18:00 hrs and flocks were followed as long as possible to record their composition. Scan samplingmethod (Altman, 1975) was used to record their behavioural activity, height of feeding, feedingsite and the role of each individual within the flock. Two minute scan samples were done with fiveminute intervals and almost all the birds participating in the flock were scanned within the twominutes time period.The flocking tendency of birds in WWSF was 28.7% and 27 flocks were studied. A total of 31 birdspecies were recorded to participate in mixed-species flocks in WWSF. These include 28 residentand 3 migrate species. Five species were endemic to Sri Lanka. The flock composition varied from3 to 15 species (5.89±2.61) and 4 to 31 individuals (I2.96±7.41). There was a positive correlationbetween the number of species and ~ock size (r= 0.796).Crested Drongo (77.78%) and Black-naped Monarch (70.37%) were the most frequent birds foundin flocks while Sri Lanka Orange-billed Babbler was the most abundant (8.78±3.67 individuals perflock). Territorial species such as Purple-romped Sunbird joined the flock when it was passingthrough their territory. Birds in mixed-species flocks in WWSF were classified as nuclear species,lead species, regular species, and occasional species. 2 major nuclear species (Crested Drongo &Sri Lanka Orange-billed Babbler), 4 lead species (Above two with Malabar Trogon and AsianParadise Flycatcher), 12 regular species, and IS occasional species were identified. Associations ofbird species participating in mixed species flocks in WWSF were studied using cluster analysis.Two main clusters could be identified, one of which could be again divided into two subassociations.The first cluster comprised of Crested Drongo and Black-naped Monarch who showedthe highest level of association. Black Bulbul and Sri Lanka Orange-billed Babbler could not bepooled into any clusters.Different species in mixed species flocks had different optimum height levels of movementthrough the forest and appeared to have characteristic feeding sites. The vertical distribution of theregular species in flocks was consistent. Sri Lanka Orange-billed Babbler was found at a widerange of foraging heights. But, Scarlet Minivet and Black Bulbul were observed mostly in thecanopy and the Crested Drongo was observed in the middle strata of the forest (10 to 20 ft). TheAsian Paradise Flycatcher was observed in the same range. However, other fly catching species(Black-naped Monarch and Tickell's Blue flycatcher) were observed mostly in the 10 to 15ftvertical range. There was an extensive overlap of height ranges between some species. But theywere observed to use different activity/feeding sites. Black-naped Monarch and Velvet-frontedBlue Nuthatch were found in the same height range, but feeding sites utilized by them wasdifferent (foliage and tree trunk respectively). Crested Drongo and Asian Paradise Flycatcher wereobserved to occupy the same vertical height range and feeding sites, but they were using differentfeeding techniques. Even being a small area of 12 ha (CEA, 1994) IIWTOUIIdedby Rubber plantations and homegardens, the Swamp Forest have a considerable flocking tendency with compared to Sinharaja Forest Reserve 30%)(Kotagama et. AI., 1986) and Knuckles Conservation Forest (30.S) (Sbriyani, 2000), thus worth conserve thehabitat
Formulation of a fertilizer package for hybrid varieties of pumpkin (Cucurbita maxima)
Pumpkin (Cucurbita maxima) is a popular low country vegetable in Sri Lanka and it has become afundamental crop species in the farming systems of dry and intermediate zones. Introduced hybridpumpkin varieties are becoming popular in Sri Lanka because ofthe higher yield. However, there isno fertilizer recommendation for hybrid pumpkin. Local farmers apply high dosages ofNitrogen(N),Phosphorus(P) and Potassium(K) levels which causes increased cost of production and reducedprofit. Therefore, a field experiment was conducted to identify the effects of higher N, P and K levelson yield of hybrid pumpkin. The hybrid variety Arjuna was tested under eight different fertilizer levelswhere the Department of Agriculture (DOA) recommendation was taken as the control and one andhalf times of that was used as the higher levels of N, P and K. The experiment was arranged in aconfounding design with three replicates with two blocks per each. Reproductive parameters andyield parameters viz. yield, number of fruits per vine, fruit width and diameter were recorded. Thetested fertilizer levels did not show any significant effect on reproductive parameters and yieldparameters of hybrid pumpkin, thus, indicating that the application of higher dosages ofN, P and K isnot economical. Hence, the DOA fertilizer recommendation is adequate for hybrid pumpkins thoughthe yield is higher when compared to local pumpkin varieties
Impact of culture towards disaster risk reduction
Number of natural disasters has risen sharply worldwide making the risk of disasters a global concern. These disasters have created significant losses and damages to humans, economy and society. Despite the losses and damages created by disasters, some individuals and communities do not attached much significance to natural disasters. Risk perception towards a disaster not only depends on the danger it could create but also the behaviour of the communities and individuals that is governed by their culture. Within this context, this study examines the relationship between culture and disaster risk reduction (DRR). A comprehensive literature review is used for the study to evaluate culture, its components and to analyse a series of case studies related to disaster risk.
It was evident from the study that in some situations, culture has become a factor for the survival of the communities from disasters where as in some situations culture has acted as a barrier for effective DRR activities. The study suggests community based DRR activities as a mechanism to integrate with culture to effectively manage disaster risk
Preliminary observations on the anopheline mosquitoes of gomadiyagala a village in the north western province of Sri Lanka
Investigations on anopheline mosquitoes were carried out in Gomadiyagaladuring January-December 1989, primarily to gather base-line data in relationtoa collaborative study between the Entomology Division, Anti-Malaria Campaignand the Department of Zoology, University of Sri Jayewardenepura on thepotential for a genetic approach for malaria control in Sri Lanka. Eight anophelinespecies were recordedfrom adult catches and lavae sampled. An. subpictusAn. culicifacies and An. varuna were the most predominant species.The only stream with two tributaries in the study area was the permanentand very productive anopheline breeding habitat. Larval and adult anophelinedensities were related to the rainfall received. The larval densities recorded indrought periods were observed to be significantly higher than those recorded inrainy periods (t=4.087, p<O.Ol). August, September and October that recordedrelatively low larval and adult An. culicifacies densities appear to be suitabletimes for field releases of genetically altered An.culicifacies in the area for malariacontrol
RNA interference to enhance radiation therapy: targeting the DNA damage response
RNA interference (RNAi) therapy is an emerging class of biopharmaceutical that has immense potential in cancer medicine. RNAi medicines are based on synthetic oligonucleotides that can suppress a target protein in tumour cells with high specificity. This review explores the attractive prospect of using RNAi as a radiosensitiser by targeting the DNA damage response. There are a multitude of molecular targets involved in the detection and repair of DNA damage that are suitable for this purpose. Recent developments in delivery technologies such nanoparticle carriers and conjugation strategies have allowed RNAi therapeutics to enter clinical trials in the treatment of cancer. With further progress, RNAi targeting of the DNA damage response may hold great promise in guiding radiation oncology into the era of precision medicine
Needle to needle robot-assisted manufacture of cell therapy products
Advanced therapeutic medicinal products (ATMPs) have emerged as novel therapies for untreatable diseases, generating the need for large volumes of high-quality, clinically-compliant GMP cells to replace costly, high-risk and limited scale manual expansion processes. We present the design of a fully automated, robot-assisted platform incorporating the use of multiliter stirred tank bioreactors for scalable production of adherent human stem cells. The design addresses a needle-to-needle closed process incorporating automated bone marrow collection, cell isolation, expansion, and collection into cryovials for patient delivery. AUTOSTEM, a modular, adaptable, fully closed system ensures no direct operator interaction with biological material; all commands are performed through a graphic interface. Seeding of source material, process monitoring, feeding, sampling, harvesting and cryopreservation are automated within the closed platform, comprising two clean room levels enabling both open and closed processes. A bioprocess based on human MSCs expanded on microcarriers was used for proof of concept. Utilizing equivalent culture parameters, the AUTOSTEM robot-assisted platform successfully performed cell expansion at the liter scale, generating results comparable to manual production, while maintaining cell quality postprocessing
Polyacetylenes from Sardinian Oenanthe fistulosa: A Molecular Clue to risus sardonicus
An investigation of Oenanthe fistulosa from Sardinia afforded oenanthotoxin (1a) and dihydrooenanthotoxin (1b) from the roots and the diacetylenic epoxydiol 2 from the seeds. The absolute configuration of 1a and 1b was established as R by the modified Mosher's method, and the structure of 2 by chemical correlation with (+)-(3R,8S)-falcarindiol. Oenanthotoxin (1a) and dihydrooenanthotoxin (1b) were found to potently block GABAergic responses, providing a molecular rationale for the symptoms of poisoning from water-dropwort (Oenanthe crocata) and related plants. These observations bear relevance for a series of historical and ethnopharmacological observations on the identification of the Sardonic herb and the molecular details of the facial muscular contraction caused by its ingestion (risus sardonicus)
Pulsed Feedback Defers Cellular Differentiation
Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable “polyphasic” positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a “timer” that operates over timescales much longer than a cell cycle
- …