Model-free time-aggregated predictions for econometric datasets

This article explores the existing normalizing and variance-stabilizing (NoVaS) method on predicting squared log-returns of financial data. First, we explore the robustness of the existing NoVaS method for long-term time-aggregated predictions. Then we develop a more parsimonious variant of the existing method. With systematic justification and extensive data analysis, our new method shows better performance than current NoVaS and standard GARCH(1,1) methods on both short- and long-term time-aggregated predictions

Combustion Characteristics of Hydrogen-methane Hybrid Fuels

ABSTRACT As the development and increasingly widespread use of IGCC and zero emission energy system, the development of advanced combustion capabilities for gaseous hydrogen and hydrogen rich fuels in gas turbine applications is becoming an area of much great concern. The combustion characteristics of hydrogen rich fuel is very different from nature gas in aspects such as flame stability, flame temperature, combustor acoustics, pollutant emissions, combustor efficiency, and some other important quantities. However, few of these issues are clearly understood by far. The purpose of this paper is to compare in detail the combustion performance of hydrogen-methane hybrid fuels with various volumetric H 2 fractions ranging from 0% to 100%. Meanwhile, the comparison of pure H 2 , pure CH 4 , and 80%H 2 +20%CH 4 was the emphasis. 80%H 2 +20%CH 4 hybrid gas is selected expressly because its component is approximately equal to the outcome of a hydrogen production test bed of our laboratory, and it is considered by the team to be a potential transition fuel of gas turbines between nature gas and pure hydrogen. Detailed experimental measurements and numerical simulations were conducted using a coflow jet diffusion burner. It was found that in the extent of experiments, when under equal general power, the flame length of hydrogen contained fuels wasn't much shorter than methane, and didn't get shorter with the increase of H 2 fraction as expected. That was because the shortening tendency caused by the increase of H 2 fraction was counteracted partially by the increase of fuel velocity, results of which was the extending of flame length. Maximum temperature of H 2 flame was 1733K, which was 30K higher than 80%H 2 +20%CH 4 and 120K higher than CH 4. All of the highest temperatures of the three fuels were presented at the recirculation zone of the flame. Although it seemed that the flame of CH 4 had the longest dimension compared with H 2 contained fuels when observed through photos, the high temperature region of flames was getting longer when increasing H 2 fractions. Curves of temperature distribution predicted by all the four combustion models in FLUENT investigated here had a departure away from the experimental data. Among the models, Flamelet model was the one whose prediction was comparatively close to the experimental results. Flame of H 2 and 80%H 2 +20%CH 4 had a much better stability than flame of CH 4 , they could reach a so called recirculating flame phase and never been blew out in the extent of experiments. On the contrary, CH 4 flames were blew out easily soon after they were lifted up. Distribution of OH concentration at the root of flames showed that the flame boundary of H 2 and 80%H 2 +20%CH 4 was more clearly than CH 4. That is to say, at the root of the flame, combustion of H 2 was the most intensive one, 80%H 2 +20%CH 4 took the second place, while CH 4 was the least. NOx emissions didn't show a linear relationship with the volumetric fraction of H 2 , but showed an exponential uptrend instead. It presented a fairly consistent tendency with flame

Precise let-7 expression levels balance organ regeneration against tumor suppression

The in vivo roles for even the most intensely studied microRNAs remain poorly defined. Here, analysis of mouse models revealed that let-7, a large and ancient microRNA family, performs tumor suppressive roles at the expense of regeneration. Too little or too much let-7 resulted in compromised protection against cancer or tissue damage, respectively. Modest let-7 overexpression abrogated MYC-driven liver cancer by antagonizing multiple let-7 sensitive oncogenes. However, the same level of overexpression blocked liver regeneration, while let-7 deletion enhanced it, demonstrating that distinct let-7 levels can mediate desirable phenotypes. let-7 dependent regeneration phenotypes resulted from influences on the insulin-PI3K-mTOR pathway. We found that chronic high-dose let-7 overexpression caused liver damage and degeneration, paradoxically leading to tumorigenesis. These dose-dependent roles for let-7 in tissue repair and tumorigenesis rationalize the tight regulation of this microRNA in development, and have important implications for let-7 based therapeutics. DOI: http://dx.doi.org/10.7554/eLife.09431.00

Model-Free Time-Aggregated Predictions for Econometric Datasets

Forecasting volatility from econometric datasets is a crucial task in finance. To acquire meaningful volatility predictions, various methods were built upon GARCH-type models, but these classical techniques suffer from instability of short and volatile data. Recently, a novel existing normalizing and variance-stabilizing (NoVaS) method for predicting squared log-returns of financial data was proposed. This model-free method has been shown to possess more accurate and stable prediction performance than GARCH-type methods. However, whether this method can sustain this high performance for long-term prediction is still in doubt. In this article, we firstly explore the robustness of the existing NoVaS method for long-term time-aggregated predictions. Then, we develop a more parsimonious variant of the existing method. With systematic justification and extensive data analysis, our new method shows better performance than current NoVaS and standard GARCH(1,1) methods on both short- and long-term time-aggregated predictions. The success of our new method is remarkable since efficient predictions with short and volatile data always carry great importance. Additionally, this article opens potential avenues where one can design a model-free prediction structure to meet specific needs

Effects of CNT and MgO–Type Expansive Agent on the Cracking Resistance of Face-Slab Concrete of CFRD

Concrete face rockfill dam (CFRD) is a commonly used and cost-effective type of dams. However, random cracks are often seen in the face slab concrete (FSC) of a CFRD during construction, largely due to the shrinkage caused by concrete temperature gradients, drying, and cementitious hydration. This study aims to improve the cracking resistance of FSC by using shrinkage compensating and cracking control materials. In this study, 5.0% by weight MgO-type expansive agent (MEA) or 0.1% by weight carbon nanotube (CNT) was added to a reference FSC (FSC-REF) selected from a CFRD. Fresh and hardened state properties of the developed concrete were tested. Different properties such as hydration heat, capillary pressure, mechanical properties at various ages, drying and autogenous shrinkage, thermal expansion coefficient (CTE), pore structure, and cracking resistance at early age of the FSC mixes (FSC-REF, FSC-MgO, and FSC-CNT) were determined. The results showed that the CNT addition lowered the capillary pressure and reduced the risk of plastic shrinkage cracking, while it also reduced drying and autogenous shrinkage of FSC. The addition of both CNT and MgO had little influence on the heat of hydration of FSC, but these slightly improved the axial tensile properties of FSC. CNT reduced the thermal expansion coefficient of FSC, whereas MgO increased it. Both CNT and MgO decreased the total porosity of the FSC, and the CNT addition significantly reduced the number of mesopores. The temperature-stress test results showed that MgO/CNT improved the cracking resistance of the FSC at early age under both temperature matching curing mode and constant temperature curing mode. Based on measured properties, CNT can be considered a promising additive for cracking control of FSC.This is a manuscript of an article published as Zhao, Zhifang, Hougui Zhou, Kejin Wang, Xu Wu, and Surendra P. Shah. "Effects of CNT and MgO–Type Expansive Agent on the Cracking Resistance of Face-Slab Concrete of CFRD." Journal of Materials in Civil Engineering 34, no. 12 (2022): 04022331. This material may be found at DOI: 10.1061/(ASCE)MT.1943-5533.0004497. Copyright 2022 ASCE. Posted with permission. This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers

Targeting ANXA1 abrogates Treg-mediated immune suppression in triple-negative breast cancer

BackgroundRegulatory T (Treg) cells play a negative role in anti-tumor immunity against triple-negative breast cancer, so it is of great significance to find the potential therapeutic target of Treg cells.MethodsFirst, Annexin A1 (ANXA1) expression and survival of patients with breast cancer were analyzed using TCGA data. Then plasma ANXA1 levels in patients with malignant and benign breast tumors were detected by ELISA. Next, the effect of ANXA1 on Treg cells was studied through suppressive assays, and how ANXA1 regulates the function of Treg cells was detected by RNA sequencing. Finally, the in vivo experiment in balb/c mice was conducted to test whether the ANXA1 blocker Boc1 could shrink tumors and affect the function of Treg cells.ResultsOur data suggest that ANXA1 expression is associated with lower survival and a higher risk of breast malignancy. Suppressive assays show that ANXA1 can enhance the inhibition function of Treg cells. RNA-Sequencing results indicate that Boc1 could reduce the expression of granzyme A mRNA in Treg cells. Animal experiments have been done to show that Boc1 can reduce tumor size and down regulate Treg cell function.ConclusionsANXA1 can enhance the function of Treg cells and reduce the survival rate of patients with breast cancer. Targeting ANXA1 can reduce Treg cell function and shrink breast tumors

Detector-device-independent quantum secret sharing with source flaws

Abstract Measurement-device-independent entanglement witness (MDI-EW) plays an important role for detecting entanglement with untrusted measurement device. We present a double blinding-attack on a quantum secret sharing (QSS) protocol based on GHZ state. Using the MDI-EW method, we propose a QSS protocol against all detector side-channels. We allow source flaws in practical QSS system, so that Charlie can securely distribute a key between the two agents Alice and Bob over long distances. Our protocol provides condition on the extracted key rate for the secret against both external eavesdropper and arbitrary dishonest participants. A tight bound for collective attacks can provide good bounds on the practical QSS with source flaws. Then we show through numerical simulations that using single-photon source a secure QSS over 136 km can be achieved

Typing and evaluating heat resistance of Bacillus cereus sensu stricto isolated from the processing environment of powdered infant formula

Bacillus cereus sensu lato is one of the most harmful bacterial groups affecting the quality and safety of powdered infant formula (PIF). In this study, samples were collected from the raw materials and processing environments of PIF. A total of 84 isolates were identified as Bacillus cereus sensu stricto (B. cereus s. s.) by 16S rRNA analysis, molecular typing technology, and physiological and biochemical tests. The 84 B. cereus s. s. strains were assigned to panC group II, group III, and group IV. Then, the 7 housekeeping genes glpF, gmk, ilvD, pta, pur, pycA, and tpi were selected for multilocus sequence typing. Results showed that the 84 isolates were clustered into 24 sequence types (ST), and 14 novel ST were detected. Among the 24 ST, ST999 (19/84, 22.62%) and ST1343 (13/84, 15.48%) predominated. The correlation between processing areas and ST showed that the processing environments of the production and packing areas were the most susceptible to contamination by B. cereus s. s. Spores of these ST showed different heat resistance phenotypes evaluated by the analysis of DT (time in minutes of spore decimal reduction at each temperature) and Z values (temperature increase required to reduce the DT value to one-tenth of the original). Spores from group III according to panC gene analysis were the most heat resistant. These findings will help us to better understand B. cereus s. s. contamination and control in PIF processing environments

Preparation of rice straw-derived biochar (RB) activated by CaCl2 and its adsorption on phosphorus

Phosphorus (P) is a limiting nutrient for plant growth in most ecosystems and a major factor for eutrophication. In the past several decades, the P removal from waste water systems has received great attention. In this paper, a rice straw-derived biochar (RB) activated by CaCl (wt=10%) was prepared for P removal from P-contained solution. The preparation conditions (including carbonization temperature and immersion rate (m/m)) and experimental parameters (including RB pack levels, adsorption time, interference ion, and initial pH of aqueous solution) were studied. Results showed that in consideration of economy, the optimal RB preparation conditions were found at carbonization temperature of 700℃ and immersion rate of 0.5; Under middle initial P loading rates (10 mg·L, based on P), the P removal efficiency could reach 97%, and the pH of solution increased from 6.87 to 9.52. The P adsorption equilibrium fit well both with the Langmuir isotherm (R=0.947) and Freundlich isotherm (R=0.892). The change of pH values and the adsorption process suggested that ion exchange was possibly the mechanism of phosphate ions adsorption by RB

Experimental Study of Bio-Security of Functionalized Single-Walled and Multi-Walled Carbon Nanotubes

In this study, the biological effects of functionalized carbon nanotubes (CNTs) were investigated on cell morphology, proliferation, apoptosis, tissue pathology and blood test in vivo & in vitro. The functionalized CNTs had good biocompatibility at lower concentrations, and the functionalized single-walled carbon nanotubes(SWCNTs) perform in the early period in the animal body and multi-walled carbon nanotubes(MWCNTs) mainly in the late. The results show successful functional groups and no change in toxicity in functional samples compared with the primary sample, and there is a safety dosage on the normal cells and tissue. In subsequent studies, antitumoral investigations of modified samples will be evaluated