Nonlinear Acoustics in Underwater and Biomedical Applications: Array Performance Degradation and Time Reversal Invariance

This dissertation describes a model for acoustic propagation in inhomogeneous flu- ids, and explores the focusing by arrays onto targets under various conditions. The work explores the use of arrays, in particular the time reversal array, for underwater and biomedical applications. Aspects of propagation and phasing which can lead to reduced focusing effectiveness are described. An acoustic wave equation was derived for the propagation of finite-amplitude waves in lossy time-varying inhomogeneous fluid media. The equation was solved numerically in both Cartesian and cylindrical geometries using the finite-difference time-domain (FDTD) method. It was found that time reversal arrays are sensitive to several debilitating factors. Focusing ability was determined to be adequate in the presence of temporal jitter in the time reversed signal only up to about one-sixth of a period. Thermoviscous absorption also had a debilitating effect on focal pressure for both linear and nonlinear propagation. It was also found that nonlinearity leads to degradation of focal pressure through amplification of the received signal at the array, and enhanced absorption in the shocked waveforms. This dissertation also examined the heating effects of focused ultrasound in a tissue-like medium. The application considered is therapeutic heating for hyperther- mia. The acoustic model and a thermal model for tissue were coupled to solve for transient and steady temperature profiles in tissue-like media. The Pennes bioheat equation was solved using the FDTD method to calculate the temperature fields in tissue-like media from focused acoustic sources. It was found that the temperature-dependence of the medium's background prop- erties can play an important role in the temperature predictions. Finite-amplitude effects contributed excess heat when source conditions were provided for nonlinear ef- fects to manifest themselves. The effect of medium heterogeneity was also found to be important in redistributing the acoustic and temperature fields, creating regions with hotter and colder temperatures than the mean by local scattering and lensing action. These temperature excursions from the mean were found to increase monotonically with increasing contrast in the medium's properties.Office of Naval Research (Code 321-TS

Copper Oxide Nanoparticles Inhibit the Metabolic Activity of \u3cem\u3eSaccharomyces cerevisiae \u3c/em\u3e

Copper oxide nanoparticles (CuO NPs) are used increasingly in industrial applications and consumer products and thus may pose risk to human and environmental health. The interaction of CuO NPs with complex media and the impact on cell metabolism when exposed to sublethal concentrations are largely unknown. In the present study, the short-term effects of 2 different sized manufactured CuO NPs on metabolic activity of Saccharomyces cerevisiae were studied. The role of released Cu2+ during dissolution of NPs in the growth media and the CuO nanostructure were considered. Characterization showed that the 28 nm and 64 nm CuO NPs used in the present study have different primary diameter, similar hydrodynamic diameter, and significantly different concentrations of dissolved Cu2+ ions in the growth media released from the same initial NP mass. Exposures to CuO NPs or the released Cu2+ fraction, at doses that do not have impact on cell viability, showed significant inhibition on S. cerevisiae cellular metabolic activity. A greater CuO NP effect on the metabolic activity of S. cerevisiae growth under respiring conditions was observed. Under the tested conditions the observed metabolic inhibition from the NPs was not explained fully by the released Cu ions from the dissolving NPs

Geographies of Absence: Radicalization and the Shaping of the New Syrian Territoriality

In November 2015, the United States and the Russian Federation convened the main international stakeholders engaged in the Syrian conflict to broker the Vienna Accords. The unfolding political process culminated in the issuing of UN Security Council Resolution 2254. Since then the situation has evolved rapidly, ushering in a new outlook for the resolution of the six-year-old civil war. The conflicting parties in Syria have not yet fathomed the momentum of this deal. Some progress has been made as part of successive attempts to establish a “cessation of hostilities,” but there have not yet been any major breakthroughs because the negotiating parties, supported by regional allies, are resisting the process every step of the way. The war has created new geographic realities: governance structures, political economies, and cultural paradigms. These geographies will not be easily bypassed. Dealing with the fragmented situation will hinder the prospects of a top-down solution, particularly because none of the negotiating parties has full control over its constituency. This article focuses on understanding this new geography. Arguing that the emergence of radicalized actors on the scene is not an accidental feature of the conflict dynamics, it shows how, instead, the territorial patterns of control by the different actors have used and exploited the territory to advance their positioning. Subsequently the article argues that these patterns, intended or not, have fostered the radicalization of the armed actors on all sides, imposing in the meantime asymmetrical patterns of territoriality that will seriously undermine the top-down approach of the Geneva process

Effects of various penetration enhancers on percutaneous absorption of piroxicam from emulgels

A suitable emulgel formulation of piroxicam was prepared and its percutaneous permeation was investigated using Wistar rat skin and diffusion cell technique. The concentrations of the drug in receptor phase of diffusion cells were measured using HPLC method. The effect of three types of penetration enhancers (Myrj 52, cineol and Transcutol P) with different concentrations on transdermal permeation of the drug was also evaluated. Flux, Kp and enhancement ratios (ERs) of piroxicam in the presence of enhancers was measured and compared with emulgel base alone and simple commercial gel. The results showed a significant enhancement in the flux from emulgel base compared to hydroalcoholic gel formulation (9.91 folds over simple gel). The highest enhancement ratio (ER=3.11) was observed for Myrj 52 at the concentration of 0.25%. Higher concentrations of Myrj 52did not show any enhancement in the drug flux due to micelle formation and solubilization of the drug by micelles. The increase in solubility, in turn, increases the saturated concentration and reduces the thermodynamic activity of the drug. Transcutol® P with concentrations higher than 0.25% w/w showed burst transportation of the drug through the skin. All concentrations of cineol and Transcutol did not show any enhancing effects over emulgel base alone (ER <1)

Kinetic analysis of drug release from nanoparticles

PURPOSE. Comparative drug release kinetics from nanoparticles was carried out using conventional and our novel models with the aim of finding a general model applicable to multi mechanistic release. Theoretical justification for the two best general models was also provided for the first time. METHODS. Ten conventional models and three models developed in our laboratory were applied to release data of 32 drugs from 106 nanoparticle formulations collected from literature. The accuracy of the models was assessed employing mean percent error (E) of each data set, overall mean percent error (OE) and number of Es less than 10 percent. RESULTS. Among the models the novel reciprocal powered time (RPT), Weibull (W) and log-probability (LP) ones produced OE values of 6.47, 6.39 and 6.77, respectively. The OEs of other models were higher than 10%. Also the number of errors less than 10% for the models was 84.9, 80.2 and 78.3 percents of total number of data sets. CONCLUSIONS. Considering the accuracy criteria the reciprocal powered time model could be suggested as a general model for analysis of multi mechanistic drug release from nanoparticles. Also W and LP models were the closest to the suggested model RPT

The study of Affordability of Vegetables in Malaysia

Kemampuan untuk membeli makanan telah menjadi kebimbangan utama bagi penduduk dunia kerana aliran harga yang menaik sejak kebelakangan ini. Kemampuan untuk membeli makanan adalah penting dalam pembangunan sesebuah negara kerana diet yang betul diperlukan untuk kehidupan yang sihat yang akan menggalakkan penduduk untuk meningkat, membuat pembaharuan dan membina idea-idea yang akhirnya akan membantu dalam kemajuan sesebuah negara. The affordability of foods has become a major concern for global population due to its upward trend of prices in recent years. The affordability of foods is crucial in the development of a nation because proper diet is required to lead a healthy lifestyle that will spur the population to improve, innovate and develop ideas that should eventually result in the advancement of a nation

The Role Of Empowerment Strategy In Organizational Crisis Management A Field Study On Urban Organizing Department In Lattakia City Council

This study aims to study the relationship between the strategy of empowerment through its dimensions (the ability to initiate and behave appropriately, the freedom of workers to act, teamwork) and the management of the random housing crisis in the Urban Organizing Department in Lattakia City Council. The research concluded that the Urban Organizing Department is less interested in the ability to initiate and behave appropriately, and its interest in the existence of teams working to solve the problem of random housing crisis, and by relying on Pearson correlation coefficient, and regression analysis And the analysis of variance using SPSS25, a relationship was reached between the freedom of workers to manage and management of the random housing crisis. هدف هذا البحث إلى دراسة العلاقة بين استراتيجية التمكين من خلال أبعاده (القدرة على المبادرة والتصرف المناسب، حرية العاملين في التصرف، العمل الجماعي) وإدارة أزمة السكن العشوائي في دائرة التنظيم العمراني في مجلس مدينة اللاذقية حيث تم توزيع استبانة على العاملين في دائرة التنظيم العمراني في مجلس مدينة اللاذقية وبلغ عددهم 33 موظف، وخلص البحث إلى انخفاض اهتمام دائرة التنظيم العمراني بالقدرة على المبادرة والتصرف المناسب، واهتمامها بوجود فرق عمل تعمل على حل مشكلة أزمة السكن العشوائي، ومن خلال الاعتماد على معامل الارتباط بيرسون، وتحليل الانحدار البسيط، وتحليل التباين باستخدام برنامج spss25, تم التوصل إلى وجود علاقة بين حرية العاملين في التصرف وإدارة أزمة السكن العشوائي