Equivalent cross-relaxation rate imaging positively correlates with pathological grade and cell density of adipocytic tumors

Objective

Equivalent cross-relaxation rate imaging (ECRI) is an MRI technique used to evaluate qualitative changes in protein-water interactions. We aimed to prospectively evaluate the utility of ECRI for classification of adipocytic tumors.

Materials and Methods

Institutional Review Board approval was obtained and all patients provided informed consent. Study participants included 40 patients with adipocytic tumors who were diagnosed with lipomas (n = 22), atypical lipomatous tissue/well-differentiated liposarcoma (ALT/WDL; n = 9), myxoid/round cell liposarcoma (MyL; n = 6), and dedifferentiated liposarcoma (DDL; n = 3), and 20 control patients for whom subcutaneous fat in the buttock or thigh was analyzed.

Results

Mean ECR values of lipomas, ALT/WDL, and subcutaneous fat were low, and those of MyL and DDL were high. Mean ECR values of MyL and DDL were significantly higher than those of ALT/WDL. The cut-off value was 5.1%. There was a positive correlation between ECR value, pathological grade, and cell density in adipocytic tumors.

Conclusion

The ECR value positively correlates with pathological grade and cell density of adipocytic tumors. Our findings suggest that ECRI is a useful method for preoperative evaluation of adipocytic tumors.     

Growth kinetics of borided layers: Artificial neural network and least square approaches

The present study evaluates the growth kinetics of the boride layer Fe₂B in AISI 1045 steel, by means of neural networks and the least square techniques. The Fe₂B phase was formed at the material surface using the paste boriding process. The surface boron potential was modified considering different boron paste thicknesses, with exposure times of 2, 4 and 6 h, and treatment temperatures of 1193, 1223 and 1273 K. The neural network and the least square models were set by the layer thickness of Fe₂B phase, and assuming that the growth of the boride layer follows a parabolic law. The reliability of the techniques used is compared with a set of experiments at a temperature of 1223 K with 5 h of treatment time and boron potentials of 2, 3, 4 and 5 mm. The results of the Fe₂B layer thicknesses show a mean error of 5.31% for the neural network and 3.42% for the least square method.     

Mdm2生成速率调控的p53-Mdm2振子的全局动力学和稳定性

肿瘤抑制蛋白p53的动力学在一定程度上可以决定DNA损伤后的细胞命运.p53的动力学行为与p53信号通路中p53-Mdm2振子模块密切相关.然而,p53的负调控子Mdm2的生成速率的增加使其在一些癌细胞中过表达.因此探讨Mdm2生成速率对p53动力学的影响有重要意义.同时,PDCD5作为p53的激活子也调控p53的表达.因此,本文针对PDCD5调控的p53-Mdm2振子模型,通过分岔分析获得了Mdm2生成速率所调控的p53的单稳态、振荡以及单稳态与振荡共存的动力学行为,且稳定性通过能量面进行了分析.此外,噪声强度对p53动力学的稳定性有重要的影响.因此,针对p53的振荡行为,探讨了噪声强度对势垒高度和周期的影响.本文所获得的结果对理解DNA损伤后的p53信号通路调控起到一定的指导作用.     

Investigation of Hybrid Optical Amplifiers for Dense Wavelength Division Multiplexed System with Reduced Spacings at Higher Bit Rates

Abstract

This article proposes various combinations of optical amplifiers for a dense wavelength division multiplexed system and investigates the impact of reduced channel spacing at high bit rates in terms of quality factor, bit error rate, eye closure, and output power. It is reported that the hybrid optical amplifier (Raman–erbium-doped fiber amplifier [EDFA]) provides better results with a maximum covered single span distance (220 km) at channel spacing of 6.25 GHz. The maximum acceptable bit rate for the 12.5-GHz channel spacing dense wavelength division multiplexed system is also investigated, and the recommendation is provided that for the Raman–EDFA, Raman–EDFA–Raman, EDFA–Raman–EDFA, and EDFA–semiconductor optical amplifier–EDFA, the operating bit rate should not be greater than 20, 16, 19, and 20 Gbps, respectively.     

Some Analytical Properties of the Model for Stochastic Evolutionary Games in Finite Populations with Non-uniform Interaction Rate

Traditional evolutionary games assume uniform interaction rate, which means that the rate at which individuals meet and interact is independent of their strategies. But in some systems, especially biological systems, the players interact with each other discriminately. Taylor and Nowak (2006) were the first to establish the corresponding non-uniform interaction rate model by allowing the interaction rates to depend on strategies. Their model is based on replicator dynamics which assumes an infinite size population. But in reality, the number of individuals in the population is always finite, and there will be some random interference in the individuals' strategy selection process. Therefore, it is more practical to establish the corresponding stochastic evolutionary model in finite populations. In fact, the analysis of evolutionary games in a finite size population is more difficult. Just as Taylor and Nowak said in the outlook section of their paper, "The analysis of non-uniform interaction rates should be extended to stochastic game dynamics of finite populations." In this paper, we are exactly doing this work. We extend Taylor and Nowak's model from infinite to finite case, especially focusing on the influence of non-uniform connection characteristics on the evolutionary stable state of the system. We model the strategy evolutionary process of the population by a continuous ergodic Markov process. Based on the limit distribution of the process, we can give the evolutionary stable state of the system. We make a complete classification of the symmetric 2×2 games. For each case game, the corresponding limit distribution of the Markov-based process is given when noise intensity is small enough. In contrast with most literatures in evolutionary games using the simulation method, all our results obtained are analytical. Especially, in the dominant-case game, coexistence of the two strategies may become evolutionary stable states in our model. This result can be used to explain the emergence of cooperation in the Prisoner is Dilemma Games to some extent. Some specific examples are given to illustrate our results.     

Skin Thickness and β-Crystals Development in Injection-Molded iPP Along the Flow Direction

In this study, iPP was injection molded at 180°C, 200°C, and 220°C. According to polarization optical microscopy (POM) results, for a given part, the skin thickness steadily decreases along the flow direction. However, at the same distance from the gate, the skin thickness of the parts molded at lower melt temperature is larger than that molded at higher melt temperature. It is found that flow time (here, the time taken for melt to pass the specific position along the flow direction) and melt temperature are two significant factors leading to this phenomenon, while the gate size is another one.

The DSC and WAXD results show that the relative fraction of β-form crystals, for a specific part, decreases along the flow direction, which is mainly determined by flow time. However, for the parts molded at different molding temperatures, the fraction of the β-form crystals is mainly determined by the molding temperature, though this influence is very complex.     

Hawking radiation as tunnelling from arbitrarily dimensional Reissner-Nordstrom de Sitter black hole

This paper extends Parikh-Wilzcek＇s recent work, which treats the Hawking radiation as a semi-classical tunnelling process from the event horizon of four dimensional Schwarzshild and Reissner-Nordstrom black holes, to that of arbitrarily dimensional Reissner-Nordstrom de Sitter black hole. The result shows that the tunnelling rate is related to the change of Bekenstein-Hawking entropy and the factually radiant spectrum is no longer precisely thermal after taking the dynamical black hole background and energy conservation into account, but is consistent with the underlying unitary theory and then satisfies the first law of the black hole thermodynamics. Meanwhile, in Parikh-Wilzcek＇s framework, this paper points out that the information conservation is only suitable for the reversible process but in highly unstable evaporating black hole （irreversible process） the information loss is possible.     

长光程共振式二氧化碳气体光声传感器研究

二氧化碳(CO₂)是植物光合作用的原材料,也是一种温室气体,其过量地排放会影响动植物的生态环境。在碳达峰、碳中和的背景下,研制高灵敏度的CO₂检测装置具有重要意义。为了监测大气环境中CO₂含量的变化,设计了一种长光程共振式CO₂气体光声传感器,并以此搭建了光声检测装置。以中心波长为2 004 nm的分布式反馈激光器(DFB)作为激发光源,激光射入由漫反射材料制成的球型吸收腔,在腔内多次反射以增加气体的吸收路径。吸收腔外部被两个高热传导率的铝制半球包裹,降低由池体吸收光能后产生的热噪声。吸收腔上耦合一根声学管,当其工作在一阶纵向共振模态时,光声信号被放大,在管子末端达到极大值。为了进一步增大光声信号,通过饱和加湿样品的方式来加快CO₂气体的弛豫速率,加湿后的样品产生的光声信号是干燥样品的2.1倍左右。使用一系列浓度的湿润CO₂样品标定光声检测装置,结果表明,光声信号与浓度之间呈现良好的线性关系。在此基础上,通过对标准气体的检测实验,验证了装置的准确性与稳定性...     

Scaling of submonolayer island growth with reversible adatom exchange in surfactant-mediated epitaxy

Surfactant-mediated epitaxial growth is studied with a realistic model, which includes three main kinetic processes: diffusion of adatoms on the surfactant terrace, exchange of adatoms with their underneath surfactant atoms, and reexchange in which an exchanged adatom resurfaces to the top of the surfactant layer. The scaling behavior of nucleus density and island size distributions in the initial stage of growth is investigated by using kinetic Monte Carlo simulations. The results show that the temperature dependence of nucleus density and island size distributions governed by the reexchanging-controlled nucleation at high temperatures exhibits similar scaling behavior to that obtained by the standard diffusion-mediated nucleation at low temperatures. However, at intermediate temperatures, the exchanging-controlled nucleation leads to an increase of nucleus density with temperature, while the island size distribution scales to a monotonically decreasing function, showing nonstandard scaling behavior.     

Extreme-value dependence: An application to exchange rate markets

Extreme value theory (EVT) focuses on modeling the tail behavior of a loss distribution using only extreme values rather than the whole data set. For a sample of 10 countries with dirty/free float regimes, we investigate whether paired currencies exhibit a pattern of asymptotic dependence. That is, whether an extremely large appreciation or depreciation in the nominal exchange rate of one country might transmit to another. In general, after controlling for volatility clustering and inertia in returns, we do not find evidence of extreme-value dependence between paired exchange rates. However, for asymptotic-independent paired returns, we find that tail dependency of exchange rates is stronger under large appreciations than under large depreciations.