CHEMOTAXIS DIFFERENTIAL EVOLUTION OPTIMIZATION TECHNIQUES FOR GLOBAL OPTIMIZATION

Nature inspired and bio-inspired algorithms have been recently used for solving low and high dimensional search and optimization problems. In this context, Bacterial Foraging Optimization Algorithm (BFOA) and Differential Evolution (DE) have been widely employed as global optimization techniques inspired from social foraging behavior of Escheria coli bacteria and evolutionary ideas such as mutation, crossover, and selection, respectively. BFOA employs chemotaxis (tumble and run steps of a bacterium in its lifetime) activity for local search whereas the global search is performed by elimination-dispersal operator. Elimination-dispersal operator kills or disperses some bacteria and replaces others randomly in the search space. This operator mimics bacterium’s death or dispersal in case of high temperature or sudden water flow in the environment. DE employs the mutation and crossover operators to make a local and a global search that explore the search space. Exploration and exploitation balance of DE is performed by two different parameters: mutation scaling factor and crossover rate. These two parameters along with the number of population have an enormous impact on optimization performance. In this thesis, two novel hybrid techniques called Chemotaxis Differential Evolution Optimization Algorithm (CDEOA) for low dimensions and micro CDEOA (μCDEOA) for high dimensional problems are proposed. In these techniques, we incorporate the principles of DE into BFOA with two conditions. What makes our techniques different from its counterparts is that it is based on two optimization strategies: exploration of a bacterium in case of its failure to explore its vicinity for food source and exploitation of a bacterium in case of its achievement to exploit more food source. By means of these evolutionary ideas, we manage to establish an efficient balance between exploration of new areas in the search space and exploitation of search space gradients. Statistics of the computer simulations indicate that μCDEOA outperforms, or is comparable to, its competitors in terms of its convergence rates and quality of final solution for complex high dimensional problems

Phenolic components, antioxidant activity, and mineral analysis of Capparis spinosa L

In addition to being consumed as food, caper (Capparis spinosa L.) fruits are also used in folk medicine to treat inflammatory disorders, such as rheumatism. C. spinosa L. is rich in phenolic compounds, making it increasingly popular because of its components’ potential benefits to human health. We analyzed a number of individual phenolic compounds and investigated in vitro biological activities of C. spinosa L. Sixteen phenolic constituents were identified using reverse phase-high performance liquid chromatography (RP-HPLC). Total phenolic compounds (TPCs), ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity were used as determinants of antioxidant capacity. C. spinosa L. exhibited strong antioxidant activity and contained high levels of antioxidant compounds. Gentisic, sinapic and benzoic acid were detected in C. spinosa L. No gallic acid, proto-catechuic acid, proto-catechuic aldehyde, chlorogenic acid, p-OH benzoic acid, vanillic acid, caffeic acid, syringic acid, vanillin, syringaldehyde, p-coumaric acid, ferulic acid or rosmarinic acid were identified. Iron and zinc were present at high levels in samples. C. spinosa L. appears to be a good source of antioxidants and minerals that might serve to protect health and combat several diseases.Key words: Antioxidant, capers, Capparis spinosa L., phenolics

Plasmon lifetime enhancement in a bright-dark mode coupled system

Metallic nanoparticles can localize the incident light to hot spots as plasmon oscillations, where the intensity can be enhanced by up to four orders of magnitude. Even though the lifetime of plasmons is typically short, it can be increased via interactions with quantum emitters, e.g., spaser nanolasers. However, molecules can bleach in days. Here, we study the lifetime enhancement of plasmon excitations due to the coupling with longer-lifetime dark plasmon modes. We apply an analytical model based on harmonic oscillators to demonstrate that a coupled system of bright and dark plasmon modes decays more slowly than the bright mode alone. Furthermore, exact solutions of the three-dimensional Maxwell equations, i.e., finite-difference time domain, demonstrate that the lifetime of the coupled system significantly increases at the hot spot, which is not predictable by far-field response. The decay of the overall energy of such a coupled system, which can be extracted from experimental absorption measurements, is substantially different from the decay of the hot spot field. This observation enlightens the plasmonic applications in which the hot spot intensity enables the detection of the optical responses.publishedVersionPeer reviewe

Enhanced Second Harmonic Generation from Coupled Asymmetric Plasmonic Metal Nanostructures

We show that second harmonic generation can be enhanced by Fano resonant coupling of asymmetric plasmonic metal nanostructures. We develop a theoretical model examining the effects of electromagnetic interaction between two metal nanostructures on the second harmonic generation. We compare the second harmonic generation efficiency of a single plasmonic metal nanostructure with that of two coupled ones. We show that second harmonic generation from a single metal nanostructure can be enhanced about 30 times by attaching a second metal nanostructure with a 10 times higher quality factor than that of the first one. The origin of this enhancement is Fano resonant coupling of the two metal nanostructures. We support our findings on Fano enhancement of second harmonic generation by an experimental study of a coupled plasmonic system composed of a silver nanoparticle and a silver nanowire on glass surface in which the ratio of the quality factors are also estimated to be around 10 times

Hand Hygiene Compliance in an Education and Research Hospital Intensive Care Units

Objective and Aim: Errors occurring during the provision of health services are medical errors. Hospital infections counted among these errors remain a serious health problem on the agenda. Hand hygiene is the most effective and cheapest way to prevent hospital infections, and it is also a method that can be easily applied by the healthcare worker. With hand hygiene compliance, it has been shown that one third of the hospital infections and even one third and half of the hospital infections occurring in intensive care are reduced. In this study, it was aimed to evaluate hand hygiene observation data retrospectively in intensive care units. Materials and Method: This study was carried out in Recep Tayyip Erdoğan University (RTEU) Training and Research Hospital Intensive Care Units (Internal Intensive Care, Surgical Intensive Care, Anesthesia Intensive Care, Cardiovascular Surgery Intensive Care, Coronary Intensive Care, Pediatric Intensive Care, Newborn Intensive Care) in 2016 and 2017. There were doctors, nurses and assistant health personnel among the healthcare professionals. Hand hygiene observation was made according to five basic indication rules. Results: In the Intensive Care Units (ICU), 255 health workers were evaluated in 2016 and 430 in 2017. The compliance rate in the ICU was evaluated as 86%. According to the five indication rules, the highest compliance was with 90-95% before aseptic procedures, after contamination with body fluids and after contact with the patient's environment. The least compliance was before contact with 60% of patients. According to professions, the compliance rate of physicians was 85%, nurses 95%, and assistant health personnel 90%. According to the units; The highest compliance was in the Surgical Intensive Care, Pediatrics and Neonatal Intensive Care Unit with 97%, and the least in the Anesthesia and Internal Medicine Intensive Care Units with 69% and 60% Discussion and Conclusion: Hand hygiene compliance; It is still below the desired levels, with regular training, evaluations and feedback. Hospital infections, especially for the prevention of intensive care infections, besides continuing education, rewarding practices will be more motivating for healthcare professionals here. It should develop and implement a feasible, acceptable, acceptable hand hygiene policy in hospitals.Keywords: Hand hygiene compliance, feedback, patient safety, intensive careDOI: 10.7176/JHMN/75-0

Electrically conductive high–performance thermoplastic filaments for fused filament fabrication

Conductive polyetherimide (PEI)-based filaments can fill the gap between the design and manufacturing of functional and structural components through additive manufacturing. This study systematically describes the fabrication of carbon nanotube (CNTs)-reinforced PEI filaments, complemented by a custom-built extrusion process facilitating low weight fraction of nanomaterials. Neat PEI and CNTs/PEI filaments at different CNTs fractions ranging from 0.1 to 7 wt. % were fabricated. Supported by morphology analysis, the rheological percolation was found to be higher (0.25 wt. % CNTs/PEI) than electrical percolation (0.1 wt. % CNTs/PEI) since the system reached an electrical percolation within the formation of a continuous conductive path at lower CNTs loadings. With the 7 wt. % CNTs loading, the highest electrical conductivity of CNTs/PEI filaments was reported as 2.57 × 10−1 S/cm. A 55% enhancement in tensile modulus was achieved when 5 wt. % CNTs were introduced, but in a trade-off in elongation at break ca. 65%