Many crucial cellular processes take place at the plasma membrane. The latter is a complex, two-dimensional medium exhibiting significant lateral structure. As a result, a number of non-classical processes, including anomalous diffusion, compartimentalisation and fractal kinetics take place at the membrane surface. The evaluation of various hypotheses and theories about the membrane is currently very difficult because no general modelling framework is available. In this thesis, we present a stochastic, spatially explicit Monte Carlo model for the plasma membrane that accounts for illmixedness, mobile lipid microdomains, fixed proteins, cytoskeletal fence structures and other interactions. We interrogate this model to obtain three classes of results, regarding (1) the effect of lipid microdomains on protein dynamics on the membrane (2) the effects of microdomains, cytoskeletal fences and fixed proteins on the nature of the (anomalous) diffusion on the membrane and (3) the effects of obstructed diffusion on reaction kinetics at the membrane. We find that the presence of lipid microdomains can lead to nonclassical phenomena such as increased collision rates and differences between long-range and short-range diffusion coefficients. Our results also suggest that experimental techniques measuring long-range diffusion may not be sufficiently discriminating and hence cannot be used to infer quantitative information about the presence and characteristics of microdomains. With regard to anomalous diffusion in particular, we find that to explain this phenomenon at the levels observed in vivo, a number of interactions are required, including (but not necessarily limited to) obstacle-induced diffusion and segregation, or exclusion from microdomains. The effects of these different interactions upon the nature of the diffusion appear to be approximately additive. Finally, we show that a widely used non-spatial method, the Stochastic Simulation Algorithm, can be modified to take into account anomalous diffusion and that this significantly increases its predictive accuracy. The model presented in this thesis is expected to be of future value in evaluating different models of cell surface processes.

Many crucial cellular processes take place at the plasma membrane. The latter is a complex, two-dimensional medium exhibiting significant lateral structure. As a result, a number of non-classical processes, including anomalous diffusion, compartimentalisation and fractal kinetics take place at the membrane surface. The evaluation of various hypotheses and theories about the membrane is currently very difficult because no general modelling framework is available. In this thesis, we present a stochastic, spatially explicit Monte Carlo model for the plasma membrane that accounts for illmixedness, mobile lipid microdomains, fixed proteins, cytoskeletal fence structures and other interactions. We interrogate this model to obtain three classes of results, regarding (1) the effect of lipid microdomains on protein dynamics on the membrane (2) the effects of microdomains, cytoskeletal fences and fixed proteins on the nature of the (anomalous) diffusion on the membrane and (3) the effects of obstructed diffusion on reaction kinetics at the membrane. We find that the presence of lipid microdomains can lead to nonclassical phenomena such as increased collision rates and differences between long-range and short-range diffusion coefficients. Our results also suggest that experimental techniques measuring long-range diffusion may not be sufficiently discriminating and hence cannot be used to infer quantitative information about the presence and characteristics of microdomains. With regard to anomalous diffusion in particular, we find that to explain this phenomenon at the levels observed in vivo, a number of interactions are required, including (but not necessarily limited to) obstacle-induced diffusion and segregation, or exclusion from microdomains. The effects of these different interactions upon the nature of the diffusion appear to be approximately additive. Finally, we show that a widely used non-spatial method, the Stochastic Simulation Algorithm, can be modified to take into account anomalous diffusion and that this significantly increases its predictive accuracy. The model presented in this thesis is expected to be of future value in evaluating different models of cell surface processes.

This thesis investigates the prospects of measuring anomalous triple gauge boson couplings in the ATLAS detector at the Large Hadron Collider (LHC). The most general(V ZZ, V = Z, g) vertex is parametrised by four couplings, fV = Z,gi=4,5 , all of which are zero in the Standard Model. Non-zero couplings would manifest themselves as an excess of events in ZZ diboson channels, and, if observed, would be a direct probe of new physics beyond the Standard Model. A set of criteria are outlined to select events recorded by ATLAS in two such channels, ZZ to llll(l = e, mu) and ZZ to llnunu. With 1 fb-1 of integrated luminosity at a centre of mass energy of sqrt(s) = 7 TeV, ATLAS can expect to observe 10+/-1 events in the ZZ to llllchannel, with 0.5+0.9-0.2 background events. In the ZZ to llnunu channel, 6.2+/-0.7 signal events are expected, with a background of 1.9+2.0-0.2 events. The expected sensitivity of ATLAS to non-zero anomalous couplings is calculated by performing extended, unbinned maximum-likelihood fits to the Z boson transverse momentum spectrum. For 1 fb-1 of integrated luminosity at sqrt(s) = 7 TeV, ATLAS has the potential to place constraints on the coupling parameters of |fZi | < 0.06 and |fig | < 0.07 at the 95% confidence level. These limits assume a form factor with a cutoff of Lambda_FF = 1.2 TeV. As a prelude to ZZ observation, criteria are defined to select Z to ll(l = e, mu) events in the first 315 nb-1 of ATLAS pp collision data at sqrt(s) = 7 TeV. In total 57 events are observed in the electron channel, with 109 in the muon channel, leading to cross-section measurements of sigma (Z to ee) = 0.70+/-0.09 (stat)+/-0.10 (syst)+/-0.08 (lumi) pband sigma(Z to mumu) = 0.90+/-0.09 (stat) +/-0.07 (syst) +/-0.10 (lumi) pb, both of which are consistent with the Standard Model predictions. In addition, this thesis presents a summary of developments made to the Data Acquisition (DAQ) system of the ATLAS Semiconductor Tracker (SCT). These include the construction of a test system, involving a scaled-down version of the entire SCT readout chain. The test system was subsequently used to develop a number of new DAQ features, including a hardware-based event simulator and monitoring framework.

The electron is known to possess an anomalous magnetic moment, which interacts with the gradient of the electric field. This makes it necessary to compute its effects on the energy spectrum. Even though the Coulomb Dirac equation can be solved in closed form, this is no longer possible when the anomalous magnetic moment is included. In fact the interaction due to this term is so strong that it changes the domain of the Hamiltonian. From a differential equation point of view, the anomalous magnetic moment term is strongly singular near the origin. As usual, one has to resort to perturbation theory. This, however, only makes sense if the eigenvalues are stable. To prove stability is therefore a challenge one has to face before actually computing the energy shifts. The first stability results in this line were shown by Behncke for angular momenta κ ≥ 3, because the eigenfunctions of the unperturbed Hamiltonian decay fast enough near the origin. He achieved this by decoupling the system and then using the techniques available for second order differential equations. Later, Kalf and Schmidt extended Behncke’s results basing their analysis on the Prüfer angle technique and a comparison result for first order differential equations. The Prüfer angle method is particularly useful because it shows a better stability and because it obeys a first order differential equation. Nonetheless, Kalf and Schmidt had to exclude some coupling constants for κ > 0. This I believe is an artefact of their method. In this study, I make increasing use of asymptotic integration, a method which is rather well adapted to perturbation theory and is known to give stability results to any level of accuracy. Together with the Prüfer angle technique, this lead to a more general stability result and even allows for an energy shifts estimate. Hamiltonians traditionally treated in physics to describe the spin-orbit effect are not self adjoint i.e. they are not proper observables in quantum mechanics. Nonetheless, naive perturbation theory gives correct results regarding the spectrum. To solve this mystery, one has to study the nonrelativistic limit of the Dirac operator. In the second part of this study, I have not only given the higher order correction to the Dirac operator but also shown the effects of the spin-orbit term.

The anomalous Hall effect (AHE) has been discovered for over a century, but its origin is still highly controversial theoretically and experimentally. In this study, we investigated the scattering effect on the AHE for both exploring the underlying physics and technical applications. We prepared Cox(MgO)100-x granular thin films with different Co volume fraction (34≤x≤100) and studied the interfacial scattering effect on the AHE. The STEM HAADF images confirmed the inhomogeneous granular structure of the samples. As x decreases from 100 to 34, the values of longitudinal resistivity (pxx) and anomalous Hall resistivity (pAHE) respectively increase by about four and three orders in magnitude. The linear scaling relation between the anomalous Hall coefficient (Rs) and the pxx measured at 5 K holds in both the as-prepared and annealed samples, which suggests a skew scattering dominated mechanism in Cox(MgO)100-x granular thin films. We prepared (Fe36/n/Au12/n)n, (Ni36/n/Au12/n)n and (Ta12/n/Fe36/n)n multilayers to study the interfacial scattering effect on the AHE. The multilayer structures were characterized by the XRR spectra and TEM images of cross-sections. For the three serials of multilayers, both the pxx and pAHE increase with n, which clearly shows interfacial scattering effect. The intrinsic contribution decreases with n increases in the three serials of samples, which may be due to the crystallinity decaying or the finite size effect. In the (Fe36/n/Au12/n)n samples, the side-jump contribution increases with nn, which suggests an interfacial scattering-enhanced side jump. In the (Ni36/n/Au12/n)n samples, the side-jump contribution decreases with n increases, which could be explained by the opposite sign of the interfacial scattering and grain boundary scattering contributed side jump. In the (Ta12/n/Fe36/n)n multilayers, the side-jump contribution changed from negative to positive, which is also because of the opposite sign of the interfacial scattering and grain boundary scattering contributed side jump. The interfacial scattering effect on the AHE is much more complicated than surface scattering in thin films or scattering by delta-impurities in bulk-like samples.

Diffusion and random walks have been studied for more than 100 years. However, there are still details in the methodology that are overlooked, and more information can be extracted from the typical data that is studied. In this thesis, I simulate random walks on two dimensional lattices with immobile obstacles configured in a variety of ways: periodic, random, and "Fuzzy" (a cross intermediate state of disorder between periodic and random). The primary goal is to develop a deeper understanding of "Fuzzy" systems by designing different ways of generating tunable disorder. An example of this is the universal Fz parameter that we developed to unify the natural disorder parameters of the various disorder generation methods we developed. Often times the importance of analysing the transient/anomalous regime with more precision and consistency is overlooked. In our work, we expand on random walk dynamics by applying non-standard probabilities, and justify our choice analytically and through a comparison of results. Furthermore we discuss how the transient regime should be analyzed so that there is consistency in the field. Other than discussing semantics of algorithms and analysis, we study the connection between the transient regime and the steady-state. We introduce two measures of the width of the transient/anomalous regime, and compare them to the crossover time. Using the width of the transient/anomalous regime we are able to provide an estimate of the steady-state diffusion coefficient without access to the steady-state simulation data.

This dissertation focuses on identifying various types of anomalous information pattern in social media and news outlets. We focus on three types of anomalous information, including (1) media censorship in news outlets, which is information that should be published but is actually missing, (2) fake news in social media, which is unreliable information shown to the public, and (3) media propaganda in news outlets, which is trustworthy information but being over-populated. For the first problem, existing approaches on censorship detection mostly rely on monitoring posts in social media. However, media censorship in news outlets has not received nearly as much attention, mostly because it is difficult to systematically detect. The contributions of our work include: (1) a hypothesis testing framework to identify and evaluate censored clusters of keywords, (2) a near-linear-time algorithm to identify the highest scoring clusters as indicators of censorship, and (3) extensive experiments on six Latin American countries for performance evaluation. For the second problem, existing approaches studying fake news in social media primarily focus on topic-level modeling or prediction based on a set of aggregated features from a col- lection of posts. However, the credibility of various information components within the same topic can be quite different. The contributions of our work in this space include: (1) a new benchmark dataset for fake news research, (2) a cluster-based approach to improve instance- level prediction of information credibility, and (3) extensive experiments for performance evaluations. For the last problem, existing approaches to media propaganda detection primarily focus on investigating the pattern of information shared over social media or evaluation from domain experts. However, these approaches cannot be generalized to a large-scale analysis of media propaganda in news outlets. The contributions of our work include: (1) non- parametric scan statistics to identify clusters of over-populated keywords, (2) a near-linear-time algorithm to identify the highest scoring clusters as indicators of propaganda, and (3) extensive experiments on two Latin American countries for performance evaluation. / Doctor of Philosophy / Nowadays, massive information is available through a variety of social media platforms. However, the information accessed by the audience might be not exactly correct in different ways. In order for the audience being able to get access to the correct information, we develop various machine learning algorithms to uncover the anomalous information pattern in social media and explain the reason behind this behavior. Our algorithms can be used to learn what different information patterns can exist in the open data source.

No / In this paper, the seasonal variations of vertical refractivity gradients and statistics of anomalous Refractive Conditions in the United Arab Emirates (UAE) have been analyzed. Nine years of local radiosonde meteorological data, from 1997 to 2005, for the lowest atmospheric layer above the ground surface have been used. Monthly variations and cumulative distributions of refractivity gradients in the first 100 meters of the atmosphere are presented.

No description available.

Yes / In this communication, nine years of local radiosonde meteorological data, from 1997 to 2005, have been used to calculate the vertical refractivity gradient, ΔN, in the lowest atmospheric layer above the ground surface. The values obtained are used to estimate the parameter β0, which represents the probability of non-standard propagation. Hourly, monthly and yearly distributions of ΔN in the first 100 meters above the ground are given. Monthly and yearly variations of the mean of ΔN and β0 are provided and the β0 values are compared with the ITU maps.