Functional structure of excess return and volatility

Capturing the relation between excess returns and volatility can help making better decisions in the stock market in terms of portfolio allocation and assets risk management. This paper takes the data of a minute-by-minute series of S&P500 from January 2009 to January 2021 as the research object and explores the best structural representation for the excess return as a function of the volatility, for a well-known index. This is implemented via regression models for volatility and excess returns. The results reveal that there’s a structural break in the relationship between the excess return and volatility based on the sign of the excess return, the functional connection could be either linear, logarithmic or quadratic

Parallel workflow tools to facilitate human brain MRI post-processing

Multi-modal magnetic resonance imaging (MRI) techniques are widely applied in human brain studies. To obtain specific brain measures of interest from MRI datasets, a number of complex image post-processing steps are typically required. Parallel workflow tools have recently been developed, concatenating individual processing steps and enabling fully automated processing of raw MRI data to obtain the final results. These workflow tools are also designed to make optimal use of available computational resources and to support the parallel processing of different subjects or of independent processing steps for a single subject. Automated, parallel MRI post-processing tools can greatly facilitate relevant brain investigations and are being increasingly applied. In this review, we briefly summarize these parallel workflow tools and discuss relevant issues

Research and simulation of fast, strong exothermic reaction in gas-solid fluidized bed about temperature distribution and hot spot problem

Gas-solid fluidized bed is widely used in petro-chemical and coal-chemical industry and other fields because of its superior heat transfer and mass transfer performances. In consideration of these performances, it is generally believed that there is a uniform temperature distribution and no hot spot in gas-solid fluidized bed compared with fixed bed. But in real industrial processes of fast, strong exothermic reactions, there are great axial and radial temperature differences and even hot spots in gas-solid fluidized bed. In this study, two-dimensional diffusion model based upon the momentum and energy conservation equations was successfully used to compute the temperature distribution of aniline reaction in fluidized bed. The result is in good agreement with real industrial measurement. In addition, this study discussed the influence of velocity and fluidized bed diameter on the temperature distribution. The result showed that in contrast to the fixed bed, increasing gas velocity during turbulent region in fluidized bed would help eliminate hot spot and reduce temperature difference. Finally, based on the comprehensive consideration of velocity and diameter, this study showed a stability region for scaling up of gas-solid fluidized bed with fast, strong exothermic reactions which helps to guide the practical operation. Please click Additional Files below to see the full abstract

Stability analysis of gas solids separation in scaling-up fluidized bed reactors

In large industrial fluidized bed reactors with high gas solids flow rates, small cyclones working in parallel are often preferred to achieve higher efficiency in the case of uniform distribution of gas-solid two-phase flow across each inlet. However, there is mounting evidence1-5 that gas-solid suspensions pass through identical paths in parallel can be significantly non-uniform, resulting in a dramatically drop in overall efficiency. In this study we used the direct Liapunov method by considering the interaction between gas and solids to detect the instability of uniformity. Owing to the special symmetry in this system, the criterion can be simplified into identifying the concavity (concave or convex) of pressure drop across a single cyclone with respect to operational parameter CT. Then, based on the stability analysis of uniformity, a novel design principle is provided to prevent non-uniform distribution at high dust loading. The effect of geometrical factor, i.e. dimensionless vortex finder diameter dr, on the stability of uniformity has been further investigated. The phase diagram of stability is calculated to give a clue of designing robust parallel cyclones system. Please click Additional Files below to see the full abstract

Load Sharing Multiobjective Optimization Design of a Split Torque Helicopter Transmission

Split torque designs can offer significant advantages over the traditional planetary designs for helicopter transmissions. However, it has two unique properties, gap and phase differences, which result in the risk of unequal load sharing. Various methods have been proposed to eliminate the effect of gap and promote load sharing to a certain extent. In this paper, system design parameters will be optimized to change the phase difference, thereby further improving load sharing. A nonlinear dynamic model is established to measure the load sharing with dynamic mesh forces quantitatively. Afterwards, a multiobjective optimization of a reference split torque design is conducted with the promoting of load sharing property, lightweight, and safety considered as the objectives. The load sharing property, which is measured by load sharing coefficient, is evaluated under multiple operating conditions with dynamic analysis method. To solve the multiobjective model with NSGA-II, an improvement is done to overcome the problem of time consuming. Finally, a satisfied optimal solution is picked up as the final design from the Pareto optimal front, which achieves improvements in all the three objectives compared with the reference design

A 5-Gb/s 66 dB CMOS variable-gain amplifier with reconfigurable DC-offset cancellation for multi-standard applications

This paper proposes a variable gain amplifier (VGA) with reconfigurable DC-offset cancellation (DCOC) for multi-standard applications. In this design, a cell-based design method and some bandwidth extension technologies are adopted to achieve a high data rate and a wide gain control range simultaneously. In addition, the DCOC having a tunable lower-cutoff frequency can make an optimum compromise between BER and SNR according to the specified baseband standard. The measurements show that the VGA achieves a gain control range from −6 dB to 60 dB, a bandwidth beyond 3 GHz, and a tunable lower-cutoff frequency from 0 to 300 kHz. When entering a 2 23 −1 pseudo-random bit sequence signal at 5 Gb/s, the VGA consumes 17 mW from a 1.2-V supply and the output data peak-to-peak jitter is less than 40 ps. The VGA is fabricated in a 90-nm CMOS process with a chip size (including all pads) of 0.52×0.5 mm 2

Regulatory mechanism of ferroptosis, a new mode of cell death

Ferroptosis is a newly discovered process of cell death that differs from apoptosis, autophagy, and pyroptosis. It is closely related to tumor formation, diseases that damage tissue, and neurodegenerative diseases. Activation of the extracellular regulated protein kinase (EPK) pathway and acylCOA synthetase long-chain family member 4 (ACSL4) are indicative of ferroptosis. During ferroptosis, the mitochondrial volume becomes smaller and the double membrane density increases. The process of ferroptosis involves disruption of the material redox reaction, and changes in the levels of cystine, glutathione, NADPH, and increase of GPX4, NOX, and ROS. Iron increases significantly in ferroptosis. Divalent iron ions can greatly promote lipid oxidation, ROS accumulation, and thus promote ferroptosis. The occurrence and progress of ferroptosis are influenced by multiple factors and signaling pathways.Keywords: Ferroptosis, Iron; Lipid, Active oxygen, Inhibitor, Induce

Niacin downregulates chemokine (c-c motif) ligand 2 (CCL2) expression and inhibits fat synthesis in rat liver cells

Purpose: To elucidate the role of chemokine (c-c motif) ligand 2 (CCL2) in fat metabolism in hepatocytes. Methods: Following partial hepatectomy, regenerated rat liver cells were isolated and cultured for 24 h were transfected with recombinant plasmid pEGFP-N1-CCL2 using liposomes. Niacin was added to the culture medium to inhibit fat synthesis. CCL2 expression was measured using western blot, while the expression of acly-coa synthetase long chain family 4 (ACSL4) and apolipoprotein E (ApoE) were assessed using real-time PCR. Results: At 12 h after transfection, GFP-positive rates in the pEGFP-N1 and pEGFP-N1-CCL2 transfection groups were 42.4 ± 5.6 % and 45.1 ± 3.5 %, respectively. Expression levels of CCL2 increased over time in pEGFP-N1 transfection group, pEGFP-N1-ccl2 transfection group, and niacin and pEGFP-N1-ccl2 transfection co-treatment group; however, CCL2 expression levels in the niacin and pEGFP-N1-ccl2 transfection co-treatment groups were similar to that of pEGFP-N1 transfection group, which were significantly lower than those of the pEGFP-N1-ccl2 transfection group. Expressionlevel trends of fat-related genes ACSL4 and ApoE were similar to that of CCL2. Conclusion: Niacin downregulates the expression of CCL2, thereby inhibiting lipid synthesis in liver cells. Keywords: Chemokine 2, Niacin, Hepatectomy, Lipid synthesis, Transfectio

Association of the RYR3 gene polymorphisms with atherosclerosis in elderly Japanese population

BACKGROUND: The Ryanodine receptor 3 gene (RYR3) encodes an intracellular calcium channel that mediates the efflux of Ca(2+) from intracellular stores. Two single-nucleotide polymorphisms (SNPs) in the RYR3 gene have been shown to associate with stroke (rs877087) and carotid intima-media thickness (rs2229116) in two independent genome-wide association studies (GWAS) in Caucasian. We investigated the effect of these two SNPs as well as the 31.1 kilobases spanning region on atherosclerosis in Japanese population. METHODS: Atherosclerotic severity was assessed by carotid artery (n = 1374) and pathological atherosclerosis index (PAI) (n = 1262), which is a macroscopic examination of the luminal surfaces of 8 systemic arteries in consecutive autopsy samples. 4 tag SNPs in the 31.1 Kb region, rs877087, rs2132207, rs658750 and rs2229116, were genotyped and haplotypes were inferred to study the association with atherosclerotic indices. RESULTS: rs877087 and rs2229116 were associated with PAI (OR = 2.07 [1.04-4.12] (95% CI), p = 0.038; and OR = 1.38 [1.02-1.86], p = 0.035, respectively). rs2229116 was also associated with common carotid atherosclerosis (OR = 1.45 [1.13-1.86], p = 0.003). The risk allele of rs2229116 was opposite from the original report. The haplotype block of this 31.1 Kb region was different between Caucasian and Japanese. Haplotype analysis revealed that only TAGG haplotype was associated with PAI (OR = 0.67 [0.48-0.94], p = 0.020) and atherosclerosis of common carotid artery (OR = 0.75 [0.58-0.98], p = 0.034). CONCLUSION: rs877087 and rs2229116 of RYR3 gene are associated with atherosclerosis severity in Japanese. The functional difference caused by rs2229116 needs to be investigated