Dark radiation and observable gravity waves from string inflation

In this thesis we work on a model of string inflation called fibre inflation. We investigate whether this inflationary model can predict a tensor-to-scalar-ratio of order 0.01 which might be detectable in the near future. The main constraint comes from the amount of axionic dark radiation produced from the inflaton decay at reheating. Very light axions are a generic feature of 4D string models and behave as extra neutrino species. We first analyze the inflationary dynamics and derive the predictions for the spectral index and the tensor-to-scalar ratio r as a function of the number of e-foldings under the requirement of generating the correct measured amplitude of the density perturbations. We then focus on reheating. We start by computing the inflaton couplings to all particles in our model: MSSM fields in the visible sector and light axions belonging to the hidden sector. This computation allows us to derive the dominant inflaton decay channels which are into Higgses, gauge bosons and light axions. In turn, these decay rates lead to a clear prediction for the amount of dark radiation in terms of extra neutrino species of about 0.5-0.6. These values require approximately 57 e-foldings which can allow for a spectral index almost 1.000 and a tensor-to-scalar-ratio around 0.01 in agreement with Planck observations in the presence of extra dark radiation. We finally point out that, due to the high inflationary scale , the supersymmetry breaking scale turns out to be too high to yield a correct Higgs mass around 125 GeV. This tension can be easily overcome if the visible sector is a simple extension of the MSSM like the NMSSM

Federated learning: A study of its applications in seizure prediction & colorectal polyp segmentation tasks.

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The rise and fall of economic development preoccupations in Argentina and the turn toward neoliberalism in the 1970s

The aim of this chapter is to offer a structured account of the transition in economic discussions in Argentina from debates on development and its relationship with industrialisation and the role of the state, to the rise of neoliberal thinking in the 1970s

Healing Mechanism Investigation of Self-Healing Concrete by Microencapsulated Calcium Nitrate

Durability of reinforced concrete structures depends highly on the integrity of the concrete which protects the structure from the environment. However, concrete is a brittle material and as such it is prone to cracking which allows for detrimental agents to penetrate the structure and produce early deterioration. Embedding microcapsules with chemical healing agents in concrete materials for self-healing applications as well as implementing SMAs as reinforcement of concrete structures for self-closing of cracks are both state-of-the-art techniques with enormous potential for enhancement of concrete infrastructure durability. In this work, both techniques are combined as an alternative for superior self-healing of cracks in concrete materials to prevent early deterioration of structures. The objective of this study was to evaluate the mechanism and effectiveness of microcapsules with encapsulated calcium nitrate on self-healing of unreinforced and reinforced (Steel and SMA) cement mortar. To fulfill this objective, short term healing efficiency (up to 28 days) of unreinforced and reinforced (Steel and SMA) mortar beam specimens with calcium nitrate containing microcapsules were evaluated under different environmental conditions (dry, water submerged, and wet and dry cycles) at different microcapsule dosages. Specimens were cracked by three-point bending test and evaluated during the healing period by light microscopy and Ultrasonic Pulse Velocity (UPV) test. Cracks analyzed ranged from 13 to 387 μm. Water submerged healing conditions yielded the best self-healing results followed by wet and dry cycles. Dry healing conditions did not enable appreciable healing, thereby suggesting the need of external moisture conditions for proper functioning of the self-healing mechanism proposed. Moreover, SMA reinforced specimens (with and without microcapsules) presented an enhanced healing performance at early stages of the healing process likely due to the self-closing effect. Furthermore, the general tendency of healing results suggested that the combination of microcapsules and SMA favored self-healing. Lastly, the healing products generated in cracks were investigated under ESEM-EDS to assess their chemical nature. The overwhelming majority of healing products were identified as likely calcium carbonate in the form of calcite crystals, and a limited quantity of gel-like healing products of possibly CSH chemical nature were also identified

Sraffa's 1920s Critique and its Relevance for the Assessment of Mainstream Microeconomics

The present essay re-examines the scope of Sraffa’s critique of Marshall’s supply curves that the former developed in his 1925 and 1926 articles showing that neoclassical supply curves derived from non-proportional returns are not robust both in the short and in the long run. After examining what a short-run and a long-run equilibrium means both for the original Sraffa’s articles and for Marshall’s pioneer contribution, the chapter discusses the common procedure in conventional economics to introduce the limitations to the growth of the firm. The argument of the chapter will be based on the 1920s articles as well as on the ‘Lectures on Advanced Theory of Value’ delivered in 1928–1931 by Sraffa at Cambridge University, now publicly available online by the Wren library, Trinity College, Cambridge. For short-run analysis, it must be assumed that the number of firms is fixed. This assumption entails serious problems with regards to the notions of competition and competitive behaviour. For long-run analysis, the sources of increasing costs are problems of management and control. However, this idea is untenable both on logical and empirical grounds. We argue that contemporary mainstream microeconomic treatment of costs and supply in the context of perfect competition still presents several problems. These problems, rather than being superficial, lie at the root of the supply and demand approach of value and distribution

Comparative aspects of the control of posture and locomotion in the spider crab Libinia emarginata

The study of pedestrian locomotion in crustaceans has largely focused on forward walking macrurans, or sideway walking brachyurans. The spider crab, Libinia emarginata is a brachyuran that, unlike its close relatives, preferentially walks forward. The phylogenetic position, behavioral preference, and amenability to experimental techniques make spider crabs an attractive model for comparative studies of crustacean locomotion. This dissertation looks at the neuroethology of forward walking in L. emarginata. I described the skeletal, muscular, and neural anatomy of the walking machinery of L. emarginata and found adaptations at each level that reflect its walking preference. The ranges of motion of leg joints aiding in forward locomotion were larger for spider crabs than for sideway walking crabs. The leg segments housing the musculature moving these joints were also larger. The proximal leg musculature consists of multiple muscle heads that can be activated independently during locomotion. The motor neurons innervating this musculature exhibited features of distantly related species that walk forward. Unlike many brachyurans, spider crabs use all ten legs during walking. Kinematic characterization of forward walking in L. emarginata showed that anterior and posterior limbs perform different functions during walking. Cross-correlation analysis among the leg joints of spider crabs revealed that distant joints have stronger coupling than adjacent ones. Neuroethology studies of pedestrian locomotion use multiple approaches. In order to understand how adaptive behavior is produced, it is necessary to study how the neural, muscular, and skeletal systems of an organism interact during its performance

Fenomenología del entrecruce del cuerpo y el mundo en Merleau-Ponty

Este artículo se propone abordar el fenómeno de la alteridad humana a partir de la obra de Maurice Merleau-Ponty. Cabe mencionar que el tema fue asignatura pendiente en la fenomenología de Husserl. Una de las estrategias que implementa Merleau-Ponty para establecer la "normalidad" en la interacción entre los hombres consiste en redimensionar el concepto de cuerpo y el de percepción. En rigor, se diría que el cuerpo no es independiente del mundo, sino que, por medio de la percepción, el cuerpo y el mundo permanecen entrecruzados

Slow sedimentation and deformability of charged lipid vesicles

The study of vesicles in suspension is important to understand the complicated dynamics exhibited by cells in vivo and in vitro. We developed a computer simulation based on the boundary-integral method to model the three dimensional gravity-driven sedimentation of charged vesicles towards a flat surface. The membrane mechanical behavior was modeled using the Helfrich Hamiltonian and near incompressibility of the membrane was enforced via a model which accounts for the thermal fluctuations of the membrane. The simulations were verified and compared to experimental data obtained using suspended vesicles labelled with a fluorescent probe, which allows visualization using fluorescence microscopy and confers the membrane with a negative surface charge. The electrostatic interaction between the vesicle and the surface was modeled using the linear Derjaguin approximation for a low ionic concentration solution. The sedimentation rate as a function of the distance of the vesicle to the surface was determined both experimentally and from the computer simulations. The gap between the vesicle and the surface, as well as the shape of the vesicle at equilibrium were also studied. It was determined that inclusion of the electrostatic interaction is fundamental to accurately predict the sedimentation rate as the vesicle approaches the surface and the size of the gap at equilibrium, we also observed that the presence of charge in the membrane increases its rigidity