Sharif Digital Repository

A new phase of matter which is known as quark-gluon plasma is created after ultrarelativistic nucleus-nucleus collisions. Experimental data imply that hydrodynamic equations can explain this new phase of matter. On the other hand, observations show that the geometry of initial energy distribution fluctuates event-by-event, even in a given centrality class. Also, the geometry of initial state distribution reflects itself as different samples of final particle spectrum results by the hydrodynamic evolution. The particle momentum distribution can be expanded by Fourier series which its coefficients called harmonic flows. We can only study the effects of hydrodynamics on initial fireball by flow... 

Entanglement is the most important quantity in quantum information processing tasks. However the provision of the required entanglement between various quantum parts is one of the most challenging breakthroughs in realization of quantum processors. One of the scenarios for entangling various parts is use of naturally interacting qubits, called “spin chains”. The low level of required control and the ability of entangling mesoscopicaly separated parts cause such systems to be attractive for using in future low dimensional silicone compatible technology quantum processors. Accordingly in this thesis by considering a ferromagnetic spin system in which is conserved and by initializing the... 

The theory of self-organized criticality is originally introduced by Bak, Tang and Wiesenfeld as a general mechanism that can explain the behaviour of complex systems which naturally organize themselves into a critical state. They defined the sandpile model as an example of slowly driven and dissipative complex system to explain the concept of self-organized criticality. From the definition of the model, extensive work has been done on this model. Thanks to the Abelian property of the model, many statistical results have been derived exactly. Other properties of the model such as critical exponents and dynamical behaviors have been also studied using the mapping with some statistical models... 

Rough surfaces and growth process are the important and significant problems of theoretical and condensed matter physics to model phenomena ranging from the extremely small (biological phenomena) to largest one (Earth’s relief). Although the equations that describe these processes are well defined, but the question of how to characterize these surfaces which display large fluctuations, is open. The existence of (often) scale invariant clusters and very large fluctuations in surface growth process are reminiscent of critical fluctuations in equilibrium systems. Therefore, it is natural to try characterizing the surface by means of critical exponents, i.e., by the scaling dimensions of various... 

In many biological populations, information about environmental conditions is acquired collectively, through information sharing among individuals, by exchanging signals. In order to achieve a better understanding of such systems, using methods borrowed from statistical physics, we introduce two mathematical models. First, a collective decision making model, for a community of individuals residing on a communication network, who live in an uncertain environment, in which individuals try to collectively find the environmental state. In the second model, a collective movement model, we consider a population of collectively moving individuals, in which individuals try to collectively find and... 

Lipases (triacylglycerol acylhydrolases) are industrial enzymes that have wide applications in the detergent, pharmaceutical and food industries. Pseudomonas aeruginosa strain is known to be suitable for lipase production due to its stability in organic solvents, resistance to temperature and pH. Lipases are usually secreted extracellularly, and its isolation from the culture medium is very important. The most cost-effective separation method is filtration which is more economical than centrifuge. Here, the use of filtration method is important from two aspects of creating clearance and maintaining enzyme activity. The equipment in this research is the filter press, whose initial tests are... 

Data representation plays an important role in machine learning and the performance of machine learning algorithms for instance, in supervised learnings (e.g. classifcation), and unsupervised ones (e.g. image denoising), are heavily influenced by the input applied to them. Regarding the fact that data usually lacks the desirable quality, efforts are always made to make a more desirable representation of data to be used as input to machine learning algorithms. Among many different representation of data, sparse data representation preserves much more information about data while it is simpler than data. We proposed a new stacked sparse autoencoder by imposing power two of smooth L0 norm of... 

In all types of chromatography for the extraction and purification of proteins, a fixed substrate is needed with which the mobile phase containing the proteins interact with them. This fixed bed should contain grains that have characteristics such as sphericity, high surface area, hydrophilicity, binding power to functional groups, chemical stability, low specific absorption, reusability and low cost. Commercially, the most commonly substrates in the ranges of the molecular weight of proteins are agarose and dextran. Agar was extracted from Gracilaria salicornia seaweed and removal of ionic groups was investigated by three methods. In washing with isopropanol, the ionic groups were reduced... 

Enzymes are biological catalysts that reduce the activation energy of a reaction in a short time and thus increase the speed of the reaction. The most common enzymes used in various industries, including the detergent industry, are lipases, amylases, celluloses, and proteases. Proteases are one of the most important industrial enzymes. The performance of enzymes is affected by the durability of their activity in long-term storage. Therefore, using a technique that can maintain the activity of enzymes, under storage and usage conditions, is an essential step in making a product containing enzymes. Stabilization-immobilization operation is one of the important downstream processes in... 

In this research, after examining the different strains available in the enzyme center's cell bank, the bacterial strain Pseudomonas aeruginosa (RPMC-B-3556) obtained from the Russian microbial collection was used for lipase production. This microbial strain has the ability to produce extracellular lipase enzyme and for this reason it has been selected as the target strain. The purpose of this research was to optimize the lipase production process in the culture of the appropriate strain. For this purpose, the compounds used in the culture medium are changed to investigate their effect on lipase enzyme activity. Considering that the studied strain has the ability to produce protease enzyme...