Surrogate Assisted Optimisation for Travelling Thief Problems

The travelling thief problem (TTP) is a multi-component optimisation problem involving two interdependent NP-hard components: the travelling salesman problem (TSP) and the knapsack problem (KP). Recent state-of-the-art TTP solvers modify the underlying TSP and KP solutions in an iterative and interleaved fashion. The TSP solution (cyclic tour) is typically changed in a deterministic way, while changes to the KP solution typically involve a random search, effectively resulting in a quasi-meandering exploration of the TTP solution space. Once a plateau is reached, the iterative search of the TTP solution space is restarted by using a new initial TSP tour. We propose to make the search more efficient through an adaptive surrogate model (based on a customised form of Support Vector Regression) that learns the characteristics of initial TSP tours that lead to good TTP solutions. The model is used to filter out non-promising initial TSP tours, in effect reducing the amount of time spent to find a good TTP solution. Experiments on a broad range of benchmark TTP instances indicate that the proposed approach filters out a considerable number of non-promising initial tours, at the cost of omitting only a small number of the best TTP solutions

Drop size in a liquid pulsed sieve-plate extraction column

Peer reviewedPublisher PD

Framed Stereotactic Brain Biopsy Outcome – Single Center Study

stereotactic biopsy. The study was conducted at the Neurospinal & Cancer Care Institute Karachi. Material and Methods:  After the approval from the ethical hospital committee, the study was conducted on 34 patients, in which 9 (26.4%) were females, and 25 (73.5%) were males. 34 consecutive patients with biopsy inclusion deep seated lesion, mid line pathology, eloquent area and operated surgery, previous radiation treatment were excluded, and after that, the biopsy report based surgery or radiotherapy treatment was decided. Result:  The biopsy underwent histopathological diagnosis proving Astrocytoma in 7 (20.5%) patients out of which four were in the Eloquent area, tuberculosis diagnosed in 5 (14.7%) patient, Oligodendroglioma diagnosed in 3 (8.8%) patients, metastasis in 5 (14.7%), Abscess in 4 (11.7%) patient which was aspirated to maximum and sent for culture, Malignant tumor (grade 3 & 4) 5 (14.7%), Lymphoma in 2 (5.8%) patient both were given radiation therapy Tumor necrosis 1 (2.9%) case,  and No tissue obtained in 2 (5.8%) which was repeated later. No major complication or side effects were observed in the patient. Conclusion:  Stereotactic Framed biopsy is safe and accurate and can be used in deep seated lesions with high success rate, minimal complication and decrease surgical morbidity for patients, and it is comparable to updated methods. &nbsp

Similarity Solutions for Hydromagnetic Free Convective Heat and Mass Transfer Flow along a Semi-Infinite Permeable Inclined Flat Plate with Heat Generation and Thermophoresis

The problem of steady, two-dimensional, laminar, hydromagnetic flow with heat and mass transfer over a semi-infinite, permeable inclined flat plate in the presence of thermophoresis and heat generation is studied numerically. A similarity transformation is used to reduce the governing non-linear partial differential equations into ordinary ones. The obtained locally similar equations are then solved numerically by applying Nachtsheim-Swigert shooting iteration technique with sixth-order Runge-Kutta integration scheme. Comparisons with previously published work are performed and the results are found to be in very good agreement. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as for the skin-friction coefficient, wall heat transfer and particle deposition rate are obtained and reported graphically for various values of the parameters entering into the problem

Transient Magnetohydrodynamic Free Convective Heat and Mass Transfer Flow with Thermophoresis past a Radiate Inclined Permeable Plate in the Presence of Variable Chemical Reaction and Temperature Dependent Viscosity

In the present study, an analysis is carried out to investigate the effects of variable chemical reaction, thermophoresis, temperature-dependent viscosity and thermal radiation on an unsteady MHD free convective heat and mass transfer flow of a viscous, incompressible, electrically conducting fluid past an impulsively started infinite inclined porous plate. The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations, which are solved numerically using a sixth-order Runge-Kutta integration scheme with Nachtsheim-Swigert shooting method. Numerical results for the non-dimensional velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the local Nusselt number and the local Stanton number are presented for different physical parameters. The results show that variable viscosity significantly increases viscous drag and rate of heat transfer. The results also show that higher order chemical reaction induces the concentration of the particles for a destructive reaction and reduces for a generative reaction

Acute-on-chronic Liver Failure: MELD Score 30-day Mortality Predictability and Etiology in a Pakistani Population

Background: Cirrhosis is a pathological condition that ultimately leads to liver failure. Acute on chronic liver failure (ACLF) has a high short term mortality rate. Viral hepatitis is the most common cause of liver failure in our local population. We carried out this study to identity the 30-day mortality and etiology of patients presenting with ACLF using Model for End-Stage Liver Disease (MELD) score predictability. Methodology: This was a descriptive case series, conducted at Sheikh Zayed Hospital, Lahore, Pakistan from January 31, 2018 to July 30, 2018. One hundred and eighty five patients who met the inclusion criteria were enrolled using 95% confidence level and 4% margin of error. Data was entered and analyzed with SPSS version 23.0. Numerical variables including age was presented by Mean ± S.D. Categorical variables i.e. gender, etiology of acute-on-chronic liver failure and 30-day mortality were presented by frequency and percentage. Data was stratified for age, gender, duration of chronic liver disease and MELD grade to address the effect modifiers. Post-stratification chi-square test was calculated using 95% significance (p≤0.05). Results: Majority of the enrolled patients were male (74.6%) while only 25.4% of the patients were female. One hundred and thirty patients (70.3%) had underlying viral hepatitis while twelve patients (6.5%) and forty three patients (23.2%) presented with alcoholic liver disease and drug-induced ACLF, respectively. Eighty patients (43.2%) died within 30 days of admission.The 30-day mortality with respect to MELD grade was statistically significant (p<0.001) with the highest mortality noted in grade-IV and thirty five patients (43.8%) dying within 30 days of admission (p<0.001). Grade-II and III MELD scores also contributed to the 30-day mortality with twenty three patients (28.8%) and nineteen patients (23.8%) dying within 30 days of admission (p<0.001). Conclusion: MELD scores are able to accurately predict the short-term mortality in patients with ACLF and viral hepatitis was the most common etiology in our population. Early detection and use of appropriate prognostic models may alleviate mortality and morbidity in paitents with ACLF

Management of myelomeningocele

Objective: T To find out best possible protocol to provide productive life to children born with myelomeningocele.Study design: Descriptive study.Place & Duration of study: Department of Neurosurgery, Jinnah Postgraduate Medical Centre Karachi from December 2001 to December 2006.Patients and Methods: The medical record of 415 children with myelomeningocele operated at our center was reviewed retrospectively. The surgical & medical management protocol used for different sites of myelomeningocele was studied.Results: The age of most of the patients at the time of myelomeningocele repair was between 25-30 days; however, children with ruptured myelomeningocele were consistently repaired early. All paraplegic patients with dorsolumbar myelomeningocele were treated with either a low-pressure ventriculoperitoneal (VP) shunt only, direct repair or both. Patients with cervical, dorsal and lumbo-sacral myelomeningocele requiring VP shunt were operated either simultaneously for both procedures or with delayed insertions of a VP shunt after treatment of ventriculitis All 16 patients with ruptured myelomeningocele (3.8%) were treated for repair as well as ventriculitis. Complications including CSF leak, wound infection or necrosis after repair of myelomeningocele occurred in 22 cases (5.3%). The postoperative follow up for all patients was 1- 2 years.Conclusions: Surgical intervention with a low-pressure VP shunt in large dorsolumbar myelomeningocele produced good results

Maternal thyroid function and child educational attainment: prospective cohort study

Objective: To determine if first trimester maternal thyroid dysfunction is a critical determinant of child scholastic performance and overall educational attainment. Design: Prospective cohort study. Setting: Avon Longitudinal Study of Parents and Children cohort in the UK. Participants: 4615 mother-child pairs with an available first trimester sample (median 10 weeks gestation, interquartile range 8-12). Exposures: Free thyroxine, thyroid stimulating hormone, and thyroid peroxidase antibodies assessed as continuous measures and the seven clinical categories of maternal thyroid function. Main outcome measures: Five age-specific national curriculum assessments in 3580 children at entry stage assessment at 54 months, increasing up to 4461 children at their final school assessment at age 15. Results: No strong evidence of clinically meaningful associations of first trimester free thyroxine and thyroid stimulating hormone levels with entry stage assessment score or Standard Assessment Test scores at any of the key stages was found. Associations of maternal free thyroxine or thyroid stimulating hormone with the total number of General Certificates of Secondary Education (GCSEs) passed (range 0-16) were all close to the null: free thyroxine, rate ratio per pmol/L 1.00 (95% confidence interval 1.00 to 1.01); and thyroid stimulating hormone, rate ratio 0.98 (0.94 to 1.02). No important relationship was observed when more detailed capped scores of GCSEs allowing for both the number and grade of pass or when language, mathematics, and science performance were examined individually or when all educational assessments undertaken by an individual from school entry to leaving were considered. 200 (4.3%) mothers were newly identified as having hypothyroidism or subclinical hypothyroidism and 97 (2.1%) subclinical hyperthyroidism or hyperthyroidism. Children of mothers with thyroid dysfunction attained an equivalent number of GCSEs and equivalent grades as children of mothers with euthyroidism. Conclusions: Maternal thyroid dysfunction in early pregnancy does not have a clinically important association with impaired child performance at school or educational achievement