Atmospheric Contrail Detection with a Deep Learning Algorithm

Aircraft contrail emission is widely believed to be a contributing factor to global climate change. We have used machine learning techniques on images containing contrails in hopes of being able to identify those which contain contrails and those that do not. The developed algorithm processes data on contrail characteristics as captured by long-term image records. Images collected by the United States Department of Energy’s Atmospheric Radiation Management user facility(ARM) were used to train a deep convolutional neural network for the purpose of this contrail classification. The neural network model was trained with 1600 images taken by the Total Sky Imager(TSI) from March 2017 and achieved an accuracy of 97.5% on the training set of images and an accuracy of 98.5% on the validation set

Atmospheric Contrail Detection with a Deep Learning Algorithm

Aircraft contrail emission is widely believed to be a contributing factor to global climate change. We have used machine learning techniques on images containing contrails in hopes of being able to identify those which contain contrails and those that do not. The developed algorithm processes data on contrail characteristics as captured by long-term image records. Images collected by the United States Deparment of Energy’s Atmospheric Radiation Management user facility(ARM) were used to train a deep convolutional neural network for the purpose of this contrail classification. The neural network model was trained with 1600 images taken by the Total Sky Imager(TSI) from March 2017 and achieved an accuracy of 97.5% on the training set of images and an accuracy of 98.5% on the validation set

Tailored metabolic workup for urolithiasis – the debate continues

Abstract Urolithiasis is one of the commonest afflictions of the urinary tract. Stones are of various chemical compositions, some share some common etiology; but most are specific to the structure and composition of stone. In view of highly recurrent nature of this condition, it is logical to have strategies for prevention. However, due to multiple factors most patients receive no or fragmented information on prevention. The current controversy is to the extent of metabolic workup in adult first time stone former. This requires longitudinal studies to show benefit in prevention strategies. Patients at high risk can have recurrence in weeks to years, depending upon the composition and attending risk factor. They should be targeted with concentric and tailored prevention protocols. The major urological guidelines (EAU and AUA) recommend basic stone workup for all patients. However, indication for detailed workup are less well documented, so one potential solution is to tailor metaphylaxis strategies for individual patient

Determinants of Housing Demand in Urban Areas of Pakistan: Evidence from the PSLM

The study attempts to investigate the determinants of housing demand in urban areas of Pakistan. The empirical analysis is carried out using the Pakistan Social and Living Standard Measurement (PSLM) survey 2004-05 and 2010-11. The hedonic price model is used for the estimation of house prices. In order to control the selectivity bias between the tenure choice and the quantity of housing services demanded, Heckman's two-step selection procedure is used. The empirical analysis shows that housing price and income (temporary and permanent) play an important role in the determination of the housing units' demand. An increase in houses' prices causes decrease in demand for the housing units while the housing demand increases when the permanent income increases. On the face of change or increase in the transitory income, the demand for housing units remains static, since people do not desire to make long-term decisions based on volatile income. To manage rising housing demand, government should focus on developing effective and enforced price control mechanisms. Keywords: Urban Housing Demand, PSLM, Pakista

The Cost of Unserved Energy: Evidence from Selected Industrial Cities of Pakistan

This study is an attempt to explore the cost of unserved energy due to power outages in Pakistan that started in 2007. The study is based on a survey conducted for four major industrial cities of Punjab—Gujrat, Faisalabad, Gujranwala, and Sialkot. In addition to quantification of output losses, the effect on employment, cost of production, and delay in supply orders are also examined. The output loss is quantified using two-dimensional analyses, controlling for variations in the duration of outages and in the shift hours. The survey data reveal that employment has not suffered any significant drop due to alternative energy arrangements. These arrangements, nevertheless, have increased the production cost of the firms. Delays in the delivery of supply orders are also due to energy shortage. The study reports that the total industrial output loss varies between 12 percent and 37 percent, with Punjab as the major affected province.Energy Crises, Output Loss, Pakistan

Quantitative determination of alliin in dried garlic cloves and products by high-performance thin-layer chromatography

Purpose: To standardize the garlic samples and its products for alliin contents.Methods: A direct high-performance thin-layer chromatographic (HPTLC) method was developed to determine alliin in Chinese (CG) and Indian garlic (IG) and two other marketed products from USA and UK, respectively. Scanning and quantification were performed at 205 nm. Furthermore, chromatography was performed on pre-coated HPTLC plates with the solvent mixture, n – hexane:ethyl acetate (29:1 v/v), as the mobile phase. In addition, the parameters suggested by International Conference on Harmonization for analytical procedures were considered to validate the proposed method.Results: The system gave a compact spot of alliin at RF = 0.19 ± 0.01 The linear regression data for the calibration plots showed a good linearity (r2 = 0.996) in the concentration range of 200 - 1600 ng. Linear regression equation was represented by Y = 1.792x + 182.855, while LOD and LOQ values were 40.42 ngband-1 and 111.72 ng.band-1, respectively. The method showed excellent accuracy with recovery of 98.20 – 99.10 % and good precision with RSD of 1 - 2.65 %.Conclusion: The proposed method is selective, sensitive and accurate for the determination of alliin in garlic and its products. It is also evident from the results obtained that raw Indian garlic has higher alliin content than Chinese garlic.Keywords: Garlic, HPTLC, Alliin, Hypercholesteremia, Quantificatio

Corporate Governance and Financing Dicisions of Listed Firms in Pakistan

The purpose of the study is to explore the link between corporate governance mechanisms and firms financing decisions. We have selected 24 banks which were listed on the “Karachi Stock Exchange”, during the period of 2008-2012. The Ownership Concentration, composition and size of the board, and role duality were considered as independent corporate governance variables while firm specific control variables were size, liquidity, profitability and tangibility of assets. Debt ratio is taken as a dependent variable representing firm’s financing decision (capital structure). The results indicate that Ownership Concentration, Size of the board, and leverage are positively correlated. However no significant relationship was found between Board composition, CEO duality and capital structure. We use panal least square regression to determine the affect of corporate governance and firm level characteristics on capital structure. Keywords: Banking Sector, Capital Structure, Corporate Governanc

Internal Corporate Governance Mechanisms and Agency Cost: Evidence from Large KSE Listed Firms

The purpose of the study is to analyze various corporate governance mechanisms that reduce agency cost. For the period 2003-2010 we have selected 120 firms on the basis of market capitalization listed on the “Karachi Stock Exchange”. We used two proxies’ asset utilisation and asset liquidity ratios to measure agency cost. A higher asset utilization ratio means lower agency cost whereas a higher asset liquidity ratio means higher agency costs. Board and committee activities, board size, CEO/Chair duality, CEO tenure, %Block ownership, %largest investor and debt financing are used as independent variables. The result shows that variables board and audit committee activities and asset utilisation ratio has strong positive correlation. However block ownership, board size, duality and asset utilization ratio appears to have negative correlation. When we use asset liquidity ratio as the dependent variable agency cost is reduced with frequent board meetings. The variables board size and CEO tenure has positive correlation with asset liquidity ratio. Block ownership and asset liquidity ratio has negative association. Furthermore variables duality, debt financing and largest investor has insignificant relation with asset liquidity ratio. Keywords: Asset Utilization Ratio, Asset Liquidity Ratio, Corporate Governance

Factors Affecting the Demand Side of Exports: Pakistan Evidence

The aim of this article is to investigate different factors affecting the demand of Pakistani exports. Factors affecting the demand of exports include real effective exchange rate, nominal exchange rate, world production capability and world export price variable. The period of the study is from 1990 to 2010. Data is gathered from various sources including State Bank of Pakistan, Karachi Stock Exchange, Handbook of statistics on Pakistan Economy, Economic Survey of Pakistan and International Financial Statistics (IFS). Two Stage Least Square (2-SLS) Method was applied in the study.  Results show that, export demand decreases with increase in Real Effective Exchange Rate. Insignificant relationship was found between the demand of Pakistani exports and export price variable and nominal exchange rate. The study also found positive and significant association between the demand of Pakistani export and World Income. Keywords: Export Growth, Foreign Direct Investment, Two Stage Least Square JEL Classifications: F13, F14, O1