Thesis advisor: Jeremy D. Shakun / Few data are available to infer the thinning rate of the Laurentide Ice Sheet (LIS) through the last deglaciation, despite its importance for constraining past ice sheet response to climate warming. We measured 31 cosmogenic 10Be exposure ages in samples collected on coastal mountainsides in Acadia National Park and from the slightly inland Pineo Ridge moraine complex, a ~100-km-long glaciomarine delta, to constrain the timing and rate of LIS thinning and subsequent retreat in coastal Maine. Samples collected along vertical transects in Acadia National Park have indistinguishable exposure ages over a 300 m range of elevation, suggesting that rapid, century-scale thinning occurred at 15.2 ± 0.7 ka, similar to the timing of abrupt thinning inferred from cosmogenic exposure ages at Mt. Katahdin in central Maine (Davis et al., 2015). This rapid ice sheet surface lowering, which likely occurred during the latter part of the cold Heinrich Stadial 1 event (19-14.6 ka), may have been due to enhanced ice-shelf melt and calving in the Gulf of Maine, perhaps related to regional oceanic warming associated with a weakened Atlantic Meridional Overturning Circulation at this time. The ice margin subsequently stabilized at the Pineo Ridge moraine complex until 14.5 ± 0.7 ka, near the onset of Bølling Interstadial warming. Our 10Be ages are substantially younger than marine radiocarbon constraints on LIS retreat in the coastal lowlands, suggesting that the deglacial marine reservoir effect in this area was ~1,200 14C years, perhaps also related to the sluggish Atlantic Meridional Overturning Circulation during Heinrich Stadial 1. / Thesis (MS) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

Reinforcement learning is the problem faced by an agent that must learn behavior through trial-and-error interactions with a dynamic environment. Generally, the problem to be solved contains subtasks that repeat at different regions of the state space. Without any guidance an agent has to learn the solutions of all subtask instances independently, which degrades the learning performance. In this thesis, we propose two approaches to build connections between different regions of the search space leading to better utilization of gained experience and accelerate learning is proposed. In the first approach, we first extend existing work of McGovern and propose the formalization of stochastic conditionally terminating sequences with higher representational power. Then, we describe how to efficiently discover and employ useful abstractions during learning based on such sequences. The method constructs a tree structure to keep track of frequently used action sequences together with visited states. This tree is then used to select actions to be executed at each step. In the second approach, we propose a novel method to identify states with similar sub-policies, and show how they can be integrated into reinforcement learning framework to improve the learning performance. The method uses an efficient data structure to find common action sequences started from observed states and defines a similarity function between states based on the number of such sequences. Using this similarity function, updates on the action-value function of a state are reflected to all similar states. This, consequently, allows experience acquired during learning be applied to a broader context. Effectiveness of both approaches is demonstrated empirically by conducting extensive experiments on various domains.

Building savings - legal and economical issues The aim of the thesis is the analysis of selected problematic issues - crucial to the functioning of building savings and also in relation to consumers and protection of its rights. The thesis is composed of six chapters which are dealing with legislation of building savings, especially with amendment in historical development with inheritance, with deposits of minors and valid way of terminating the contract of minors, with the bank charges in the context of preparatory transposition of 2014/17/ EU Directives on housing loans, and compares the economic aspects of both component of building savings with competitive products in the financial market. In the thesis I use the method of analysis, synthesis and induction in chapters in which I work with jurisprudence and in which I advocate a position of building savings in the banking market. In anticipation of the upcoming law on housing loans I require to include information obligation into the proposed legislation with emphasis not only on formal form but the content of communication. I confront the selected issues with valid jurisprudence and mention the original statutory framework and its new version after the recodification of private law and I pointed out the differences which the recodification...

<p>Rechargeable lithium ion batteries (LIBs) are widely used in various daily life applications including electronic portable devices, cell phones, military applications, and electric vehicles throughout the world. The demand for building a safer and higher volumetric/gravimetric energy density LIBs has increased exponentially for electronic devices and electric vehicles. With the high energy density and longer cycle life, the LIBs are the most prominent energy storage system for electric vehicles. Researchers are further exploring for new materials with a high specific capacity, the MXene has been a promising new anode material for LIBs. The typical MXene material Ti₃C₂T_z has 447mAh/g theoretical capacity, which is higher than traditional graphite (372 mAh/g for LiC₆) based anode.</p> <p>Though LIBs are used in most of the portable energy storage devices, LIBs are still having thermal runaway safety concern, which is caused by three main reasons: mechanical, electrical, and thermal abuse. The thermal runaway is caused by the initiation of solid electrolyte interface (SEI) degradation above 80 °C on the anode surface, generating exothermic heat, and further increasing battery temperature. The SEI is a thin layer formed on anode due to electrolyte decomposition during first few charging cycles. Its degradation at low temperature generates heat inside the LIBs and triggers the thermal runaway. The thermal runaway follows SEI degradation, electrolyte reactions, polypropylene separator melting, cathode decomposition and finally leads to combustion. The thermal runaway mechanism of graphite, which is the most common and commercialized anode material of LIBs, has been studied for years. However, the thermal safety aspects of the new MXene material has not been investigated yet. </p> <p>In this thesis, we primarily used differential scanning calorimetry (DSC) and specially designed multi module calorimetry (MMC) to measure exothermic and endothermic heat generated at <a>Ti₃C₂T_z </a>anode, associated with multiple chemical reactions as the temperature increases. The <i>in-situ</i> MMC technique is employed to study the interactions and chemical reactions of all the components (separator, electrolyte, cathode and MXene anode) in the coin cell for the first time, while the <i>ex-situ</i> DSC is used to investigate the reactions happened on anode side, including electrolyte, PVDF binder, MXene, SEI and intercalated Li. Along with other <a>complementary </a>instruments and methods, the morphological, structural and compositional studies are carried out using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area measurement and electrochemical measurement to support the thermal analysis. The electrochemical and thermal runaway mechanism of conventional graphitic anode is studied and used for comparison with MXeneanodes.</p> <p>The Ti₃C₂T_z thermal runaway is triggered by SEI decomposition around 120 °C analogous to conventional graphite. The thermal behavior of Ti₃C₂T_z anode is highly dependent on electrode material, surface area, lithiation states, surface morphology, structure and surface-terminating functional groups on Ti₃C₂T_z, which provides more active lithium sites for exothermic reactions with the electrolyte. Especially the terminal groups (-OH, -F, =O, etc.) from the etching process affect the lithium ion intercalation and thermal runaway mechanism. With annealing treatment, the surface-terminating functional groups are modified and can achieve less exothermic heat release. By normalizing the total heat generation by specific capacities of the anode materials, it is observed that Ti₃C₂T_z (2.68 J/mAh) generates slightly less exothermic heat than graphite (2.72 J/mAh) indicating slightly safer nature of Ti₃C₂T_z anode. The <i>in-situ</i> thermal analysis results on the Ti₃C₂T_z half-cell exhibited less total heat generation per mass (1.56 kJ/g) compared to graphite (1.59 kJ/g) half-cell. </p><br>