Stability theory applications to laminar-flow control

In order to design Laminar Flow Control (LFC) configurations, reliable methods are needed for boundary-layer transition predictions. Among the available methods, there are correlations based upon R sub e, shape factors, Goertler number and crossflow Reynolds number. The most advanced transition prediction method is based upon linear stability theory in the form of the e sup N method which has proven to be successful in predicting transition in two- and three-dimensional boundary layers. When transition occurs in a low disturbance environment, the e sup N method provides a viable design tool for transition prediction and LFC in both 2-D and 3-D subsonic/supersonic flows. This is true for transition dominated by either TS, crossflow, or Goertler instability. If Goertler/TS or crossflow/TS interaction is present, the e sup N will fail to predict transition. However, there is no evidence of such interaction at low amplitudes of Goertler and crossflow vortices

Heavy Quark Potential in a static and strong homogeneous magnetic field

We have investigated the properties of quarkonia in a thermal QCD medium in the background of strong magnetic field. For that purpose, we employ the Schwinger proper-time quark propagator in the lowest Landau level to calculate the one-loop gluon self-energy, which in the sequel gives the the effective gluon propagator. As an artifact of strong magnetic field approximation ($eB>>T^2$ and $eB>>m^2$), the Debye mass for massless flavors is found to depend only on the magnetic field which is the dominant scale in comparison to the scales prevalent in the thermal medium. However, for physical quark masses, it depends on both magnetic field and temperature in a low temperature and high magnetic field but the temperature dependence is very meagre and becomes independent of temperature beyond a certain temperature and magnetic field. With the above mentioned ingredients, the potential between heavy quark ($Q$) and anti-quark ($\bar Q$) is obtained in a hot QCD medium in the presence of strong magnetic field by correcting both short and long range components of the potential in real-time formalism. It is found that the long range part of the quarkonium potential is affected much more by magnetic field as compared to the short range part. This observation facilitates us to estimate the magnetic field beyond which the potential will be too weak to bind $Q\bar Q$ together. For example, the $J/\psi$ is dissociated at $eB \sim$ 10 $m_\pi^2$ and $\Upsilon$ is dissociated at $eB \sim$ 100 $m_\pi^2$ whereas its excited states, $\psi^\prime$ and $\Upsilon^\prime$ are dissociated at smaller magnetic field $eB= m_\pi^2$, $13 m_\pi^2$, respectively.Comment: 20 pages, 5 figure

The growth of Goertler vortices in compressible boundary layers

The linear instability of Goertler vortices in compressible boundary layers is considered. Using asymptotic methods in the high wavenumber regime, it is shown that a growth rate estimate can be found by solving a sequence of linear equations. The growth rate obtained in this way takes non-parallel effects into account and can be found much more easily than by ordinary differential equation eigenvalue calculations associated with parallel flow theories

Health Care Workers of Rawalpindi Medical University: The Vanguards at the COVID-19 War

COVID-19 has been ravaging the world since November 2019, when the first case was detected. The population affected by this affliction is well North of 21 million cases worldwide. The hardest-hit countries include the USA (5.5 Million), Brazil (3.3 Million), and India (2.6 Million), accounting for nearly 55% of all cases. No part of the world has been left untouched by the plague and at this point, daily cases seem to be only increasing, with more than 250,000 cases, being reported worldwide daily. Close to 775,000 individuals have fallen prey to this disease, with the daily death tally averaging north of 5000 cases.1 14.5 million people have recovered to date, demonstrating a closed case mortality rate of 5

The commercialisation of BDS through an NGO: case study of AKRSP-Pakistan

Book ChapterBased on the theme of how donors can play a more effective role to stimulate effective and sustainable provision of BDS by or through private sector intermediaries, this case study looks at how the Aga Khan Rural Support Programme (AKRSP) has sought to encourage the development of markets for Business Development Services (BDS) in the remote areas of northern Pakistan. This paper explores that the isolation of the region, poor infrastructure, small scale of landholdings, and lack of economic development leads to problems when attempting to promote markets for business development services. In the short term, the priority is the development of more basic markets, rather than markets for business development services. Without active markets there are a few opportunities for BDS provision let alone the development of vibrant private sector markets for BDS. It specifies the geographic, economic, political, and institutional context in which the AKRSP’s interventions have been implemented. Grassroots village based initiatives have been discussed, where groups of farmers are facilitated by AKRSP to provide BDS to neighboring farmers (farmers interest groups in Chitral), along with more structured formal approaches such as the more direct provision of BDS through commercial entity associated with AKRSP (North South Seeds). It is argued that both models have a positive impact on MSME performance and lead to market development in the long run. Both are methods through which donors can promote BDS markets but which model is most appropriate depends on the market being served. Where the service offered is relatively simple and the business of the BDS provider is relatively straight-forward, facilitating private sector intermediaries may be the most effective way of creating markets for BDS. However, where the service is complex and there is a need to establish a sophisticated organisation to provide the service, it may be necessary to set up an organisation within the NGO, on commercially sustainable basis if possible, with a view to fully commercialising and ideally privatising the organisation over time

Supersonic laminar-flow control

Detailed, up to date systems studies of the application of laminar flow control (LFC) to various supersonic missions and/or vehicles, both civilian and military, are not yet available. However, various first order looks at the benefits are summarized. The bottom line is that laminar flow control may allow development of a viable second generation SST. This follows from a combination of reduced fuel, structure, and insulation weight permitting operation at higher altitudes, thereby lowering sonic boom along with improving performance. The long stage lengths associated with the emerging economic importance of the Pacific Basin are creating a serious and renewed requirement for such a vehicle. Supersonic LFC techniques are discussed

Temporal trends in hepatitis B and C infection in family blood donors from interior Sindh, Pakistan

<p>Abstract</p> <p>Background</p> <p>Hepatitis B (HBV) and C (HCV) infections are a serious global and national public health problem. Earlier studies have reported increasing rates of hepatitis infection in Pakistan, particularly in rural areas. Pakistan has no active surveillance program to monitor trends of these infections. The objective of this study was to verify this trend in blood donors from the rural Sindh area of the country.</p> <p>Methods</p> <p>The study analysed the data of blood donors of interior Sindh who donated blood at JPMC blood bank from January 1, 2004 to September 15, 2007. HBsAg status was determined by using HBsAg Serodia kit and antibodies to HCV using the Detect HCV ™ V.3 Kit. Samples repeatedly reactive for HBsAg or anti-HCV were considered positive for HBV or HCV infection respectively.</p> <p>Results</p> <p>The overall seroprevalence of HBV infection among donors was 6.2 % (95% CI 5.5%–6.9%) and did not change significantly over the study period. Overall seroprevalence of HBV infection in literate blood donors was 5.7 %(95% CI 4.7%–6.8%). Prevalence decreased significantly in this group over the study period (p = 0.05). No other significant trends in seroprevalence of HBV infection were seen in the stratified analyses.</p> <p>The overall seroprevalence of HCV among donors was 7.5% (95% CI 6.8%–8.3%) and increased significantly over the study period from 7.2% (95% CI 5.8%–8.7%) in 2004 to 8.9% (95% CI 7.4%–10.6%) in 2007 (p = 0.02). Significant increase in seroprevalence was particularly seen in literate (p = 0.03), non–first time (p = 0.01) and Sindhi speaking (p = 0.01) donors.</p> <p>Conclusion</p> <p>Our study finds a steady increase in the prevalence of HCV infection in blood donors from interior Sindh between 2004 and 2007. On the contrary, decreasing prevalence of HBV was found, particularly in literate blood donors. There may be a need to have rural community-based epidemiological studies to identify the determinants of the spread of HCV infection and also those that are limiting the spread of HBV infection particularly in the literate blood donor population.</p

Large-Eddy Simulation of Axisymmetric Compression Corner Flow

The Wall-Modeled Large Eddy Simulation (WMLES) approach is used to study the interaction of a shock wave with a high Reynolds number turbulent boundary layer. Since the near wall region is modeled, high Reynolds number turbulent flows can be simulated at a moderate computational cost. The case considered is that of an axisymmetric Mach 2.85 turbulent boundary layer over a 30 compression corner. The Reynolds number of the boundary layer upstream of the interaction based on momentum thickness (Re theta = u sub infinity theta/v sub infinity) is ~12,000. The geometry and flow conditions match the experiments of Dunagan et al. (NASA TM 88227, 1986). The simulations were performed using equilibrium and non-equilibrium wall models. The agreement with experiment is encouraging for the finest grid with respect to the separation bubble length, unsteady shock structure and wall pressure distribution. Sensitivity ofWMLES results to grid, wall model, and blockage effects in the tunnel are reported

DOES BRAND EXTENSION IMPACT PARENT BRAND: A CASE OF JOHNSON, UK

Purpose of study: The main purpose of this study is to check the impact of brand extensions on brand image. For this purpose Johnson is selected as parent brand for current research. The targeted brand extensions are Johnson shampoo, Johnson’s isotonic drinks, Johnson’s sports wear and Johnson’s suntan lotion. Research Methodology: sample was selected from Bradford, UK. Sample consists of graduate students including males as well as female. Total sample size is 60 and data was collected through self administered questionnaires. For each brand 15 respondents were selected. Convenient sampling was selected as sampling technique. Results: Results show that Johnson’s have high brand awareness and perceived quality. While there is negative correlation results for brand fit on brand image for those product extensions which are not in same brand category i.e. Johnson’s sportswear and Johnson’s isotonic drinks. Conclusion: It is concluded from study results that launching new product in same parent brand category have high chance of success while in different category is risk.Brand Extension, Brand Fit, Johnson, Product extensions, marketing.