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

Numerical Fitting-based Likelihood Calculation to Speed up the Particle Filter

The likelihood calculation of a vast number of particles is the computational bottleneck for the particle filter in applications where the observation information is rich. For fast computing the likelihood of particles, a numerical fitting approach is proposed to construct the Likelihood Probability Density Function (Li-PDF) by using a comparably small number of so-called fulcrums. The likelihood of particles is thereby analytically inferred, explicitly or implicitly, based on the Li-PDF instead of directly computed by utilizing the observation, which can significantly reduce the computation and enables real time filtering. The proposed approach guarantees the estimation quality when an appropriate fitting function and properly distributed fulcrums are used. The details for construction of the fitting function and fulcrums are addressed respectively in detail. In particular, to deal with multivariate fitting, the nonparametric kernel density estimator is presented which is flexible and convenient for implicit Li-PDF implementation. Simulation comparison with a variety of existing approaches on a benchmark 1-dimensional model and multi-dimensional robot localization and visual tracking demonstrate the validity of our approach.Comment: 42 pages, 17 figures, 4 tables and 1 appendix. This paper is a draft/preprint of one paper submitted to the IEEE Transaction

Oral transmucosal delivery of naratriptan

Naratriptan (NAR) is currently used as the hydrochloride salt (NAR.HCl) for the treatment of migraine and is available in tablet dosage forms for oral administration. Buccal drug delivery offers a number of advantages compared with conventional oral delivery including rapid absorption, avoidance of first pass metabolism and improved patient compliance. We have previously prepared and characterised the base form of NAR and shown that it has more favourable properties for buccal delivery compared with NAR.HCl. This study describes the design and evaluation of a range of formulations for oral transmucosal delivery of NAR base. Permeation studies were conducted using excised porcine buccal tissue mounted in Franz cells. Of the neat solvents examined, Transcutol® P (TC) showed the greatest enhancement effects and was the vehicle in which NAR was most soluble. The mechanisms by which TC might promote permeation were further probed using binary systems containing TC with either buffer or Miglyol 812® (MG). Mass balance studies were also conducted for these systems. The permeation of TC as well as NAR was also monitored for TC:MG formulations. Overall, TC appears to promote enhanced membrane permeation of NAR because of its rapid uptake into the buccal tissue. Synergistic enhancement of buccal permeation was observed when TC was combined with MG and this is attributed to the increased thermodynamic activity of NAR in these formulations. Significantly enhanced permeation of NAR was achieved for TC:MG and this was also associated with less TC remaining on the tissue or in the tissue at the end of the experiment. To our knowledge this is the first report where both enhancer and active have been monitored in buccal permeation studies. The findings underline the importance of understanding the fate of vehicle components for rational formulation design of buccal delivery systems

Ceramides: a new player in the inflammation-insulin resistance paradigm?

No abstract available

Drop size in a liquid pulsed sieve-plate extraction column

Peer reviewedPublisher PD

Craniosynostosis: Clinical Presentation and Outcome of Surgical Treatment

Objective:  Craniosynostosis presents sclerosis cranial sutures, ossification and fusion involving the vault of the base, sutures involved can be one or more sutures. This study aimed to determine the surgical outcome of craniosynostosis. Material and Method:  The prospective study was conducted at the neuro spinal and cancer care institute, Karachi. Patients presented with sagittal, metopic, unicoronal, lambdoid, bicoronal craniosynostosis were included in the study, while patients with coagulopathy, previously operated cases were excluded from the study. Results:  We had 26 children in our study, age range about 1–3 years. Patients were cleaved into groups depending on their age. Most of the children 15 (57.6%) were in 1–2 years age group and 11 (42.3%) were in 2-3 years of age. Boys were 18 (69.2%) and girls were 8(30.7%). Coronal 11 (42.3%) was the most common suture involved, followed by sagittal 9 (34.6%). Lambdoid suture 3 (11.5%), metopic 2 (7.6%) and 3 (11.5%) case presented with raised intracranial pressure with multiple sutures closed involved. Strip craniectomy was done in all cases. We did bicoronal flap and Scalp flap turned into a supraorbital region while in metopic suture Fronto-orbital advancement and remodeling approach were used. No major complication was observed. Conclusion:  Cases which are managed early age have given good acceptable results in follow up, proper surgical expertise, perioperative management of temperature, blood loss, relieving the restriction of sutures and normalizing raised intracranial pressure can decrease the morbidity and mortality