Laser Diode Induced Lighting Modules

Laser diodes have the potential of becoming the light engines of future lighting technology since they have negligible efficiency droop factor, unlike light emitting diodes. This study demonstrates the possibility of laser diodes coupled to phosphor targets being used as a solid state lighting system with high power applications. It was revealed that white light emitting modules with efficiency of up to 217 lumens per watt based on laser diodes can currently be made and upon further development of laser diode technology and relevant phosphor materials there is room for further improvements. The report also demonstrates the ability of this technology to produce a tailored emission spectrum for a given specific requirement. Two test lamp prototypes were made using laser diodes and phosphor targets and their emission characteristics were investigatedBrunel University London & EPSRC grant No. EP/K504208/

Artificial Neural Networks to Predict Sheet Resistance of Indium-Doped Zinc Oxide Thin Films Deposited via Plasma Deposition

We implemented deep learning models to examine the accuracy of predicting a single feature (sheet resistance) of thin films of indium-doped zinc oxide deposited via plasma sputter deposition by feeding the spectral data of the plasma to the deep learning models. We carried out 114 depositions to create a large enough dataset for use in training various artificial neural network models. We demonstrated that artificial neural networks could be implemented as a model that could predict the sheet resistance of the thin films as they were deposited, taking in only the spectral emission of the plasma as an input wi

Lift & Project Systems Performing on the Partial-Vertex-Cover Polytope

We study integrality gap (IG) lower bounds on strong LP and SDP relaxations derived by the Sherali-Adams (SA), Lovasz-Schrijver-SDP (LS+), and Sherali-Adams-SDP (SA+) lift-and-project (L&P) systems for the t-Partial-Vertex-Cover (t-PVC) problem, a variation of the classic Vertex-Cover problem in which only t edges need to be covered. t-PVC admits a 2-approximation using various algorithmic techniques, all relying on a natural LP relaxation. Starting from this LP relaxation, our main results assert that for every epsilon > 0, level-Theta(n) LPs or SDPs derived by all known L&P systems that have been used for positive algorithmic results (but the Lasserre hierarchy) have IGs at least (1-epsilon)n/t, where n is the number of vertices of the input graph. Our lower bounds are nearly tight. Our results show that restricted yet powerful models of computation derived by many L&P systems fail to witness c-approximate solutions to t-PVC for any constant c, and for t = O(n). This is one of the very few known examples of an intractable combinatorial optimization problem for which LP-based algorithms induce a constant approximation ratio, still lift-and-project LP and SDP tightenings of the same LP have unbounded IGs. We also show that the SDP that has given the best algorithm known for t-PVC has integrality gap n/t on instances that can be solved by the level-1 LP relaxation derived by the LS system. This constitutes another rare phenomenon where (even in specific instances) a static LP outperforms an SDP that has been used for the best approximation guarantee for the problem at hand. Finally, one of our main contributions is that we make explicit of a new and simple methodology of constructing solutions to LP relaxations that almost trivially satisfy constraints derived by all SDP L&P systems known to be useful for algorithmic positive results (except the La system).Comment: 26 page

Optical analysis of RF sputtering plasma through colour characterization

© 2019 by the authors. The photometric properties of an radio frequency (RF)-based sputtering plasma source were monitored through optical spectroscopy. The colour of the plasma source was deduced based on conventional chromaticity index analysis and it was compared to the direct spectral data plots of the emission peaks to investigate the possibility of characterising the plasma based on its specific colour and exploring the potential of defining a new method by which the plasma sputtering process can be addressed based on the plasma colour parameters. The intention of this investigation is to evaluate the possibility of simplifying the monitoring and assessment of the sputtering process for applied scientists operating plasma sputter deposition systems. We demonstrate a viable potential for this technique in terms of providing information regarding the stability of the plasma, chamber pressure, and plasma power; however, further work is underway to verify and assess a relationship between the quality of the thin film coating and the colour characteristics of the deposition plasma. Here, we only focus on the feasibility of such an approach and demonstrate interesting observations. We observed a linear relationship between the colour functions and the plasma power, while the stability of the sputtering plasma can be assessed based on the plasma colour functions. The colour functions also follow a unique pattern when the working gas pressure is increased

The limits of filopodium stability

Filopodia are long, finger-like membrane tubes supported by cytoskeletal filaments. Their shape is determined by the stiffness of the actin filament bundles found inside them and by the interplay between the surface tension and bending rigidity of the membrane. Although one might expect the Euler buckling instability to limit the length of filopodia, we show through simple energetic considerations that this is in general not the case. By further analyzing the statics of filaments inside membrane tubes, and through computer simulations that capture membrane and filament fluctuations, we show under which conditions filopodia of arbitrary lengths are stable. We discuss several in vitro experiments where this kind of stability has already been observed. Furthermore, we predict that the filaments in long, stable filopodia adopt a helical shape

Management of bird and other wildlife hazards at Tribhuvan International Airport, Kathmandu, Nepal

Tribhuvan International Airport (TIA), the only international airport in the Himalayan Kingdom of Nepal, is geographically situated in the middle of the country at an elevation of 4,390 feet (AMSL) in a valley surrounded by hills. The airport was in an isolated area at the time of its establishment in 1949, but now is in the middle of dense human settlement and local market places. The polluted rivers on either side of runway, un-scientific municipal solid waste management, and emergence of earthworms near the runway and taxiways after monsoon rains in late summer are some of the bird attractants. Birds of prey such as kites, eagles, vultures, and falcons are major bird types hazardous to aircraft operations at TIA. There were 6 separate bird strike incidents to civil aircraft during August-October 2000. In one of these incidents, an engine of a B-757 aircraft was heavily damaged. The Airport authority took several immediate measures to prevent bird strikes, including minimizing garbage dumping near airport and shooting birds that would not disperse. Short, medium and long-term plans have been developed to solve the problem systematically. In order to address the bird strike problem, a national level Bird Strike Control Committee and individual airportlevel Bird Strike Committees have been formed following the incidents in 2000. The Royal Nepal Academy of Science and Technology (RONAST) presently is carrying out research on bird activities in and around the airport. The Civil Aviation Authority of Nepal is committed to reducing bird and other wildlife hazards at all airports in Nepal by developing integrated management programs

Study of malignant tumours of the uterine corpus: histopathology and immunohistochemistry

Background: The uterine corpus represents the second most common site for malignancy in the female genital tract. This study was performed to ascertain the profile of malignant tumours of the uterine corpus reported at our centre.Methods: A retrospective analysis of cases retrieved from the archives of the department of pathology from January 2014 to December 2016. Clinical information of the patients was collected from the hospital records.  Classification and grading of the tumours were done according to the current WHO classification.Results: Nineteen cases were studied. There were ten cases of endometrial adenocarcinoma, five cases of leiomyosarcoma, three cases of endometrial stromal sarcoma and one case of carcinosarcoma(malignant mixed mullerian tumour). The age range of endometrial adenocarcinoma was 55 to 85 years and presented with post menopausal bleeding, whereas endometrial stromal sarcomas occurred in women above 45 years of age. Leiomyosarcomas had age range from 26 to 65 years. All leiomyosarcomas were clinically diagnosed as fibroid. Majority of endometrial adenocarcinomas were well differentiated endometroid type. Out of the three endometrial stromal sarcomas two were high grade, one with metastasis. All leiomyosarcomas showed mitotic rate above 10/10hpf.Conclusions: Endometrial carcinomas form the majority of malignant tumours of uterine corpus and occur in older age group followed by leiomyosarcomas. Endometrial stromal sarcomas are less common and occur in middle aged and older patients. Leiomyosarcomas and stromal sarcomas are usually misdiagnosed as fibroids clinically unless metastases are present

Spatiotemporal profile of dendritic outgrowth from newly born granule cells in the adult rat dentate gyrus.

Neurogenesis in the adult dentate gyrus occurs in the subgranular zone where newborn neurons (NNs) migrate a short distance into the granule cell layer and extend their rudimentary apical dendritic processes upon a radial glial scaffold. Using doublecortin (DCX) immunocytochemistry, these growing dendrites can be visualized because dendritic growth cones, including filipodia and lamellipodia, are labeled in both light and electron microscopic preparations. To study the rate of dendritic outgrowth of newborn dentate granule cells, single injections of 5-bromo-2-deoxyuridine (BrdU) with different survival times were combined with double immunolabeling for BrdU and DCX. At the earliest time points (4 and 12 h after BrdU injections), a rudimentary process can be observed to emanate from BrdU/DCX double-labeled cells. By 48 h the dendrites first appeared in the molecular layer. By 96 h after BrdU injection, these apical dendrites extended into the middle of the molecular layer where they ramified. The calculated rate of dendritic growth for NNs was about 15 microm per day for the first 3 days, and then a doubling in length occurred at 4 and 5 days that coincided with a retraction of the basal dendrite. In addition, electron microscopy of DCX-labeled apical dendrites showed that they were much thinner (1/4 to 1/3 the size) in diameter than unlabeled, mature apical dendrites and that they had developing synapses on them in the molecular layer