Mutual Fund Theorem for continuous time markets with random coefficients

We study the optimal investment problem for a continuous time incomplete market model such that the risk-free rate, the appreciation rates and the volatility of the stocks are all random; they are assumed to be independent from the driving Brownian motion, and they are supposed to be currently observable. It is shown that some weakened version of Mutual Fund Theorem holds for this market for general class of utilities; more precisely, it is shown that the supremum of expected utilities can be achieved on a sequence of strategies with a certain distribution of risky assets that does not depend on risk preferences described by different utilities.Comment: 17 page

Deep Neural Networks - A Brief History

Introduction to deep neural networks and their history.Comment: 14 pages, 14 figure

Memory Hierarchy Hardware-Software Co-design in Embedded Systems

The memory hierarchy is the main bottleneck in modern computer systems as the gap between the speed of the processor and the memory continues to grow larger. The situation in embedded systems is even worse. The memory hierarchy consumes a large amount of chip area and energy, which are precious resources in embedded systems. Moreover, embedded systems have multiple design objectives such as performance, energy consumption, and area, etc. Customizing the memory hierarchy for specific applications is a very important way to take full advantage of limited resources to maximize the performance. However, the traditional custom memory hierarchy design methodologies are phase-ordered. They separate the application optimization from the memory hierarchy architecture design, which tend to result in local-optimal solutions. In traditional Hardware-Software co-design methodologies, much of the work has focused on utilizing reconfigurable logic to partition the computation. However, utilizing reconfigurable logic to perform the memory hierarchy design is seldom addressed. In this paper, we propose a new framework for designing memory hierarchy for embedded systems. The framework will take advantage of the flexible reconfigurable logic to customize the memory hierarchy for specific applications. It combines the application optimization and memory hierarchy design together to obtain a global-optimal solution. Using the framework, we performed a case study to design a new software-controlled instruction memory that showed promising potential.Singapore-MIT Alliance (SMA

Evaluation of DVFS techniques on modern HPC processors and accelerators for energy-aware applications

Energy efficiency is becoming increasingly important for computing systems, in particular for large scale HPC facilities. In this work we evaluate, from an user perspective, the use of Dynamic Voltage and Frequency Scaling (DVFS) techniques, assisted by the power and energy monitoring capabilities of modern processors in order to tune applications for energy efficiency. We run selected kernels and a full HPC application on two high-end processors widely used in the HPC context, namely an NVIDIA K80 GPU and an Intel Haswell CPU. We evaluate the available trade-offs between energy-to-solution and time-to-solution, attempting a function-by-function frequency tuning. We finally estimate the benefits obtainable running the full code on a HPC multi-GPU node, with respect to default clock frequency governors. We instrument our code to accurately monitor power consumption and execution time without the need of any additional hardware, and we enable it to change CPUs and GPUs clock frequencies while running. We analyze our results on the different architectures using a simple energy-performance model, and derive a number of energy saving strategies which can be easily adopted on recent high-end HPC systems for generic applications

Inhalation of high-concentration hydrogen gas attenuates cognitive deficits in a rat model of asphyxia induced-cardiac arrest.

Cognitive deficits are a devastating neurological outcome seen in survivors of cardiac arrest. We previously reported water electrolysis derived 67% hydrogen gas inhalation has some beneficial effects on short-term outcomes in a rat model of global brain hypoxia-ischemia induced by asphyxia cardiac arrest. In the present study, we further investigated its protective effects in long-term spatial learning memory function using the same animal model. Water electrolysis derived 67% hydrogen gas was either administered 1 hour prior to cardiac arrest for 1 hour and at 1-hour post-resuscitation for 1 hour (pre- & post-treatment) or at 1-hour post-resuscitation for 2 hours (post-treatment). T-maze and Morris water maze were used for hippocampal memory function evaluation at 7 and 14 days post-resuscitation, respectively. Neuronal degeneration within hippocampal Cornu Ammonis 1 (CA1) regions was examined by Fluoro-Jade staining ex vivo. Hippocampal deficits were detected at 7 and 18 days post-resuscitation, with increased neuronal degeneration within hippocampal CA1 regions. Both hydrogen gas treatment regimens significantly improved spatial learning function and attenuated neuronal degeneration within hippocampal CA1 regions at 18 days post-resuscitation. Our findings suggest that water electrolysis derived 67% hydrogen gas may be an effective therapeutic approach for improving cognitive outcomes associated with global brain hypoxia-ischemia following cardiac arrest. The study was approved by the Animal Health and Safety Committees of Loma Linda University, USA (approval number: IACUC #8170006) on March 2, 2017

Unequal-mass boson-star binaries: Initial data and merger dynamics

We present a generalization of the curative initial data construction derived for equal-mass compact binaries in Helfer {\it et al} (2019 Phys. Rev. D 99 044046; 2022 Class. Quantum Grav. 39 074001) to arbitrary mass ratios. We demonstrate how these improved initial data avoid substantial spurious artifacts in the collision dynamics of unequal-mass boson-star binaries in the same way as has previously been achieved with the simpler method restricted to the equal-mass case. We employ the improved initial data to explore in detail the impact of phase offsets in the coalescence of equal- and unequal-mass boson star binaries.Comment: 37 pages, 12 figures, to match published version in CQ

The Gravitational Afterglow of Boson Stars

In this work we study the long-lived post-merger gravitational wave signature of a boson-star binary coalescence. We use full numerical relativity to simulate the post-merger and track the gravitational afterglow over an extended period of time. We implement recent innovations for the binary initial data, which significantly reduce spurious initial excitations of the scalar field profiles, as well as a measure for the angular momentum that allows us to track the total momentum of the spatial volume, including the curvature contribution. Crucially, we find the afterglow to last much longer than the spin-down timescale. This prolonged gravitational wave afterglow provides a characteristic signal that may distinguish it from other astrophysical sources.Comment: Movie: https://youtu.be/JE5FRG7kgvU Data: https://github.com/ThomasHelfer/BosonStarAfterglo

Effects of Poisson's ratio on the deformation of thin membrane structures under indentation

Deformation/deflection of thin shells/membranes with clamped boundaries is a common material behaviour relevant to many engineering and medical conditions. A detailed understanding of the deformation mechanisms of different materials/structures with different Poisson's ratios under such a loading condition is of great significance to materials testing and product development. In this work, the deformation of circular elastic membranes with a clamped edge under point loading and finite contact conditions is systematically studied incorporating auxeticity behaviours. The effect of Poisson's ratio on the deformation of the material is investigated and the influence of parameters including sample thickness, indentation depth and indenter size is analysed. The feasibility and limitation of an analytical solution is evaluated. The work shows that the P/δ3 relationship is applicable to describe the force–displacement data over the membrane domain for both point loading and finite contact conditions. It is shown that negative Poisson's ratios have direct influence on the membrane deformation domain, including the force–displacement curve, the deflection profile and the contact area. Critical factors affecting the P–h curves and the deformation mechanisms are discussed with reference to potential use of the Poisson's ratio effect

Severity of Nonalcoholic Fatty Liver Disease is Associated with Development of Metabolic Syndrome: Results of a 5-Year Cohort Study

Aims: Nonalcoholic fatty liver disease (NAFLD) is considered to be a hepatic manifestation of metabolic syndrome (MS). However, a few studies have examined the effect of NAFLD on the development of MS. We evaluated the relationship between the development of MS and clinical severity of NAFLD according to alanine aminotransferase (ALT) levels. Methods: A retrospective cohort study was conducted. Participants who underwent abdominal ultrasonography and blood samplings for health check-ups both in 2005 and 2010 were recruited. NAFLD was diagnosed if a person showed fatty liver on ultrasonography without significant alcohol consumption. Subjects with MS at baseline were excluded. Results: A total of 2,728 subjects met the inclusion criteria. Fatty liver (FL) with normal ALT was found in 369 (13.5%) subjects and FL with elevated ALT in 328 (12.0%). During 5 years of follow up, 582 (21.3%) incident cases of MS developed between 2005 and 2010. The incidence of MS was higher in patients with NAFLD compared to control group (41.2% in FL with elevated ALT, 34.7% in FL with normal ALT and 15.7% in control, p<0.001). Multivariate analysis showed that odds ratio (OR) and 95% confidence interval (CI) for MS increased according to the severity of NAFLD [OR (95% CI), 1.29 (0.97−1.71) in FL with normal ALT and 1.54 (1.18−1.33) in FL with elevated ALT, p=0.01]. Conclusions: We have demonstrated that development of MS is significantly increased according to the clinical severity of NAFLD. These findings have implications in the clinical availability of NAFLD as a predictor of MS