Labour Market Dynamics in Pakistan: Evidence from the Longitudinal Data

The bulk of research on labour market conditions in Pakistan has concentrated on the economic activity rate, the number of employed persons, or the unemployment rate at a particular point in time. These stock measures of labour market situation are useful from a policy viewpoint as they give a broad indication of the dimension of the problem. For example, the recent labour force surveys show an increase in the level of open unemployment from 5.9 percent in 1997-98 to 7.8 percent in 1999-2000 [Pakistan (2001)]. There is also an emerging consensus that during the 1990s poverty has increased at the national as well as for rural and urban areas of the country [Qureshi and Arif (2001)]. Labour market is considered as the main route for establishing the link between macro policies, the resulting GDP growth and poverty alleviation [Rahman (2002)]. Interim Poverty Reduction Strategy Paper (IPRSP) and other development plans have suggested various targets of employment creation for poverty reduction. The stock measures of labour market conditions, such as unemployment rate, are considered to be inadequate from the viewpoint of developing appropriate policy responses. There is a need to gain further insights by examining the structure of labour market in terms of its dynamic components: these being the turnover of persons into and out of the labour force and turnover into and out of employment and unemployment pools

Formulation and physicochemical evaluation of toothpaste formulated with Thymus vulgaris essential oil

Introduction: Streptococcus mutans is the most common cause of tooth decay. Parabens, and other commonly used as anti-Streptococcus agents in toothpaste industry have numerous side effects such as discoloration of teeth. Thymus vulgaris essential oil has profound antimicrobial activity against a wide range of species. The aim of present study was the aim of the present study was to formulate and evaluate the physicochemical properties of a kind of toothpaste formulated with Thymus vulgaris essential oil. Thyme oil components were also analyzed using gas chromatography–mass spectrometry (GC-MS).Methods: Toothpaste was formulated in forms of gel and opaque and Thyme essence was added to it. The formulation was evaluated in terms of stability in different temperatures, pH, consistency, uniformity, taste, smell, and compatibility with special packaging for toothpaste at three temperatures. Profilometry was used to determine abrasivity. The rate of contaminations with lead and arsenic was determined by atomic absorption. The amount of fluoride was measured by potentiometry.Results: Forty-one different components, representing 99.64 of the total oil were identified in essential oil. Addition of thyme essence to formulation had no deleterious effect in stability, consistency, taste and smell. The pH of opaque and gel formulations was 7.02 and 7.45, respectively. The abrasiveness of opaque and gel formulations was in standard ranges. The fluoride content was 1000 ppm. Lead and arsenic were not detected at all.Conclusion: Formulation of toothpaste with T. vulgaris essential oil was acceptable and might be considered as a desirable herbal toothpaste

Laminar flow of two miscible fluids in a simple network

When a fluid comprised of multiple phases or constituents flows through a network, non-linear phenomena such as multiple stable equilibrium states and spontaneous oscillations can occur. Such behavior has been observed or predicted in a number of networks including the flow of blood through the microcirculation, the flow of picoliter droplets through microfluidic devices, the flow of magma through lava tubes, and two-phase flow in refrigeration systems. While the existence of non-linear phenomena in a network with many inter-connections containing fluids with complex rheology may seem unsurprising, this paper demonstrates that even simple networks containing Newtonian fluids in laminar flow can demonstrate multiple equilibria. The paper describes a theoretical and experimental investigation of the laminar flow of two miscible Newtonian fluids of different density and viscosity through a simple network. The fluids stratify due to gravity and remain as nearly distinct phases with some mixing occurring only by diffusion. This fluid system has the advantage that it is easily controlled and modeled, yet contains the key ingredients for network non-linearities. Experiments and 3D simulations are first used to explore how phases distribute at a single T-junction. Once the phase separation at a single junction is known, a network model is developed which predicts multiple equilibria in the simplest of networks. The existence of multiple stable equilibria is confirmed experimentally and a criteria for their existence is developed. The network results are generic and could be applied to or found in different physical systems

Retrospective model-based inference guides model-free credit assignment

An extensive reinforcement learning literature shows that organisms assign credit efficiently, even under conditions of state uncertainty. However, little is known about credit-assignment when state uncertainty is subsequently resolved. Here, we address this problem within the framework of an interaction between model-free (MF) and model-based (MB) control systems. We present and support experimentally a theory of MB retrospective-inference. Within this framework, a MB system resolves uncertainty that prevailed when actions were taken thus guiding an MF credit-assignment. Using a task in which there was initial uncertainty about the lotteries that were chosen, we found that when participants’ momentary uncertainty about which lottery had generated an outcome was resolved by provision of subsequent information, participants preferentially assigned credit within a MF system to the lottery they retrospectively inferred was responsible for this outcome. These findings extend our knowledge about the range of MB functions and the scope of system interactions

SQG-Differential Evolution for difficult optimization problems under a tight function evaluation budget

In the context of industrial engineering, it is important to integrate efficient computational optimization methods in the product development process. Some of the most challenging simulation-based engineering design optimization problems are characterized by: a large number of design variables, the absence of analytical gradients, highly non-linear objectives and a limited function evaluation budget. Although a huge variety of different optimization algorithms is available, the development and selection of efficient algorithms for problems with these industrial relevant characteristics, remains a challenge. In this communication, a hybrid variant of Differential Evolution (DE) is introduced which combines aspects of Stochastic Quasi-Gradient (SQG) methods within the framework of DE, in order to improve optimization efficiency on problems with the previously mentioned characteristics. The performance of the resulting derivative-free algorithm is compared with other state-of-the-art DE variants on 25 commonly used benchmark functions, under tight function evaluation budget constraints of 1000 evaluations. The experimental results indicate that the new algorithm performs excellent on the 'difficult' (high dimensional, multi-modal, inseparable) test functions. The operations used in the proposed mutation scheme, are computationally inexpensive, and can be easily implemented in existing differential evolution variants or other population-based optimization algorithms by a few lines of program code as an non-invasive optional setting. Besides the applicability of the presented algorithm by itself, the described concepts can serve as a useful and interesting addition to the algorithmic operators in the frameworks of heuristics and evolutionary optimization and computing