Metformin effect on internal carotid artery blood flow assessed by area under the curve of carotid artery Doppler in women with polycystic ovarian syndrome

BACKGROUND Insulin resistance(IR)was reported in most polycystic ovarian syndrome(PCOS)cases.Metformin,a biguanide drug,successfully reduced IR.Homeostatic Model Assessment for IR(HOMA-IR)and Doppler parameters assessed metformin's effectiveness.AIM To verify whether the area under the curve of the internal carotid artery(AUC-ICA)Doppler wave can be a useful marker for assessing IR among PCOS cases who presented with menstrual irregularity and were treated with metformin over 6 mo.METHODS An observational,cross-sectional study recruited 54 eligible PCOS women;the anthropometrics were as follows:age,body mass index(BMI),menstrual cycle days,biochemical serum cholesterol,low and high-density lipoprotein,sex hormone-binding globulin,fasting blood glucose,and HOMA-IR,hormonal testosterone,luteinizing hormone over follicle-stimulating hormone ratio,and ultrasonic pulsatility index(PI)and resistance index(RI),carotid artery intima-media thickness(CIMT)and(AUC-ICA)parameters were initially recorded and repeated 3 mo and 6 mo later with metformin tab 500 mg;three times/day for 6 mo.In addition,AUC-ICA was assessed by taking repeated systolic and diastolic wave height measurements.RESULTS Metformin caused a progressive reduction in BMI,menstrual cycle days,biochemical hormonal,and Doppler parameters(CIMT,PI,RI,and AUC-ICA).AUC-ICA correlated strongly to all PCOS parameters.AUC-ICA correlated inversely with treatment time(r=-0.98,P<0.001)and positively with HOMA-IR(r=0.98,P<0.0001).Via the best subset regression model,the AUC-ICA had the highest predictive value for HOMA-IR.CONCLUSION AUC-ICA preceded PI,RI,and CIMT with a strong,meaningful correlation to all PCOS parameters,making it a reliable marker for the assessment of IR,especially during metformin therapy.Further studies are recommended to promote the application in practice.

The Electric Mechanism of Surface Pretreatments for Dye-Sensitized Solar Cells Based on Internal Equivalent Resistance Analysis

Based on the optimization of dye-sensitized solar cell (DSC) photoelectrodes pretreated with different methods such as electrodeposition,spin-coating and TiCl_(4) pretreatment,theoretical calculations are carried out to interpret the internal electric mechanism.The numerical values,including the series resistance R_(s) and the shunt resistance R_(sh) corresponding to the equivalent circuit model,are well evaluated and confirm that the DSC has good performance with a high R_(sh) and a low R_(s) due to good electrical contact and a low charge recombination after the different modifications.The Ⅰ-Ⅴ curves are fifted in the case without series resistance,and account for the role of R_(s) in the output characteristics.It is found that when R_(s) tends to the infinitesimal,the short-circuit current Isc,the open-circuit voltage V_(oc) and the fill factor can be improved by almost 0.8-1.4,2.9 and 2.1-6.8%,respectively.

Resistance Factor of Caisson-Tip with Internal Fillet for Suction Caissons Penetrating into Clay

This paper presents failure mechanisms of the soil at the caisson-tip with fillet during suction-assisted penetration of suction caissons in undrained clay.Theoretical solutions of resistance factor N_c of the caisson-tip are obtained in terms of the caisson-tip geometry ratio of the flat section of the caisson-tip to the caisson wall thickness m/t and adhesion factorsα_i along inside of caisson wall andα_b at the base of the caisson-tip.It is indicated that the factor N_c increases with the increase of m/t,α_i and a_b.The resistance factors N_c for the rough base(α_b=1)are larger by 0.57than that for the smooth base(α_b=0).Besides,the factors N_c of caisson-tip with flat base(m=t)are larger by 1.14 than that with full internal fillet(m=0).The required suction to penetrate suction caissons with various fillets is obtained in terms of the force equilibrium in vertical direction.The finite element limit analysis and centrifuge model test results are used to verify the rationality of the presented failure mechanisms and theoretical predictions.

Low Cycle Fatigue and Strengthening Mechanism of Cold Extruded Large Diameter Internal Thread of Q460 Steel

large diameter internal thread of high-strength steel（LDITHSS） manufactured by traditional methods always has the problems of low accuracy and short life. Compared with traditional methods, the cold extrusion process is an effective means to realize higher accuracy and longer life. The low-cycle fatigue properties of LDITHSS are obtained by experiments, and the initiation and propagation of fatigue cracks are observed by scanning electron microscope（SEM）. Based on the mechanical properties, surface microstructure and residual stress, the strengthening mechanism of cold extruded large diameter internal thread（LDIT） is discussed. The results show that new grains or sub-grains can be formed on the surface of LDIT due to grain segmentation and grain refinement during cold extrusion. The fibrous structures appear as elongated and streamlined along the normal direction of the tooth surface which leads to residual compressive stress on the extruded surface. The maximum tension stress of LDIT after cold extrusion is found to be 192.55 k N. Under low stress cycling, the yield stress on thread increases, the propagation rate of crack reduces, the fatigue life is thus improved significantly with decreasing surface grain diameter and the average fatigue life increases to 45.539×10~3 cycle when the maximum applied load decreases to 120 k N. The low cycle fatigue and strengthening mechanism of cold extruded LDIT revealed by this research has significant importance to promote application of internal thread by cold extrusion processing.

Experimental study on thermal characteristics of LiFePO_4 power batteries

As an important high-energy chemical power source, lithium-ion power batteries come up to application problems of thermal performance, such as extended temperature range and high power charge ＆ discharge. LiFeP04 battery is applied and developed well recently, its charge and discharge experiment at different temperatures and hybrid pulse power characterization （HPPC） test are analyzed, and the optimal temperature range of LiFeP04 battery is put forward. In order to provide experimental suggestion of power battery application and its thermal management, internal resistance, influencing factor of electromotive force and entropy change state of charge （SOC）, battery thermal characteristic of different charge ＆ discharge rates are summarized.

Application of thermal electrochemical equation to metal-hydride half-cell system

Application of thermal electrochemical equation to metal-hydride half-cell system was investigated, and the influence of state of charge on the thermal electrochemical performance of hydrogen storage materials was studied. The results show that both the absolute value of the molar enthalpy change and the internal resistance of evolution hydrogen reaction are less than that of absorption hydrogen reaction at the same state of charge. The molar reaction enthalpy change of absorption and evolution of hydride electrode change contrarily with the enhancement of filling degree of hydrogen in hydride electrode. The relation curve of molar reaction enthslpy change to state of charge, both absorption and evolution hydrogen reaction, is close to a constant when the state of charge is 10%- 60%, and during state of charge below 10% or state of charge above 60%, the molar reaction enthalpy change varies sharply. Meanwhile, the internal resistance of electrode reaction has an ascending trend with the enhancement on filling degree of hydrogen in hydride electrode in both absorption and evolution hydrogen reaction.

Poor Knowledge of Tuberculosis among the Population of Jeddah and Makkah Saudi Arabia, a High-Risk Area

SETTING: Millions of pilgrims visit Makkah (Mecca), Saudi Arabia, from regions of endemic tuberculosis. Little consideration has been given to the potential impact of this disease on the local population. OBJECTIVES: To assess knowledge about TB among residents of Makkah and Jeddah (Makkah’s principal travel gateway). METHODS: A cross-sectional survey of 1004 residents. Data were analyzed by gender. RESULTS: Spread of TB by coughing was a transmission route known by 44.2% of males and 59.6% of females (P < 0.001);20.0% of participants knew that TB is caused by bacteria;71.6% of females and 52.3% of males knew TB is infectious (P < 0.001). Regarding approaches to TB prevention, 48.0% of respondents answered patient isolation and 15.2% vaccination. Overall, 50.6% of males and 38.3% of females (P < 0.001) would seek modern medical treatment if hemoptysis occurred. With a persistent cough, 65.4% of respondents would do nothing or wait before consulting a healthcare provider. High numbers of “don’t know” responses were recorded throughout the survey. CONCLUSIONS: Within the population across pilgrimage areas in Saudi Arabia, knowledge is lacking concerning TB transmission, the cause of the disease, means of prevention and the success of treatment, highlighting an urge need for better public education.

Efficacy and Risk Factors Associated to Resistance to Single-Agent Chemotherapy in Low-Risk Gestational Trophoblastic Neoplasia

Objectives: This study aimed to assess efficacy of intramuscular methotrexate 8-day protocol in the treatment of low-risk gestational trophoblastic neoplasia and also identify prognostic factors associated with treatment failure, necessitating second line chemotherapy. Methods: This study was performed at Gynaecologic and Obstetric Clinic of Dakar Teaching Hospital, the reference Centre of Gestational Trophoblastic Disease in Senegal. At the beginning of 2011, patients were followed according to FIGO’s recommendations. From 2011 to 2014, we diagnosed 88 low-risk gestational trophoblastic neoplasia (GTN) patients (WHO score < 7). Low-risk patients started their treatment with methotrexate (MTX) based on the 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day. Resistance to treatment was the main outcome. We studied the association of different prognostic factors included in the World Health Organisation (WHO) scoring system and resistance to the initial single agent chemotherapy. Results: Eighty-eight patients were diagnosed for GTN during the study period. Average age was 31 years. The antecedent pregnancy was molar in 98.1% of cases. Seventy-four patients underwent remission after single agent-chemotherapy. Resistance rate to single-agent chemotherapy was 15.9% (14 patients). Nine of them achieved remission after second line chemotherapy. WHO score was significantly associated with the risk of resistance to single-agent chemotherapy. Other variables included in the WHO as age, antecedent pregnancy, pre-treatment hCG, tumour size and FIGO stage were not significantly associated with resistance. We report five fatal cases. Conclusion: The 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day is effective for women with LRGTN. The only significant prognostic factor for failure is pretreatment WHO score. We highly recommend the use of this protocol particularly in developing countries where methotrexate is available, affordable and relatively safe.

The Myth of the High-Efficiency External-Combustion Stirling Engine

The reported discrepancy between theory and experiment for external combustion Stirling engines is explained by the addition of thermal resistance of the combustion gasses to the standard Carnot model. In these cases, the Stirling engine ideal efficiency is not as is normally reported equal to the Carnot cycle efficiency but is significantly lower. A new equation for ideal Stirling engine efficiency when the heat is obtained through external combustion without pre-heating the air, is presented and results for various fuels tabulated. The results show that petrol and diesel, internal combustion engines (Otto cycle) have a higher ideal efficiency than the Stirling engine. When comparing thermoacoustic engines heated by wood, efficiency should not be quoted as a percentage of the Carnot efficiency, but against a figure 48% lower than Carnot. The effect is not seen with electrically heated rigs, solar or nuclear fission heated engines.

Prediction and parametric analysis of 3D borehole and total internal thermal resistance of single U-tube borehole heat exchanger for ground source heat pumps

The borehole and total internal thermal resistance are both significant parameters in evaluating the thermal performance of the ground source heat pump.This study aimed to obtain the accurate correlation of the 3D borehole and total internal thermal resistance(R_(b,3D)and R_(a,3D))and analyze the impacts of parameters on the R_(b,3D)and R_(a,3D).Firstly,eight parameters affecting the R_(b,3D)and R_(a,3D),including the borehole diameter,pipe diameter,pipe-pipe distance,borehole depth,soil thermal conductivity,grout thermal conductivity,pipe thermal conductivity,and fluid velocity inside the pipe,were considered and an L-54 design matrix was generated.Then,the 3D numerical model,coupling with the four-resistance model,was proposed to calculate R_(b,3D)and R_(a,3D)for each case.After that,the response surface methodology was employed to obtain and verify the correlation of R_(b,3D)and R_(a,3D),which were compared with the existing resistance calculation methods.Lastly,analysis of variance was carried out to reveal parameters that have statistically significant impacts on the R_(b,3D)and R_(a,3D).Results show that the rationality and accuracy of the correlation of R_(b,3D)and R_(a,3D)can be verified by the determination coefficient and P value of regression model,as well as the P value of lack-of-fit.The existing resistance calculation methods are more or less inaccurate and the discrepancies in some cases can be up to 86.74%and 111.35%for the borehole and total internal thermal resistance.The pipe and grout thermal conductivity,pipe and borehole diameter,and the pipe-pipe distance can be seen as the significant contributory factors to the variation of R_(b,3D)and R_(a,3D).

Effect of Black Plate on Corrosion Resistance of T5 Tinplate

The effect of black plate on corrosion resistance of T5 tinplate was studied by glow discharge spectrograph, X-ray diffractometer （XRD）, stress tester, roughness tester and metallographic microscope. The result shows that black plate influences corrosion resistance of T5 tinplate intensely. It also indicates that the increase of content of manganese, phosphorus, silicon and aluminum in black plate would reduce the corrosion resistance of T5 tinplate and the increase of degree of crystal orientation on （200） crystal face, ｜X-Y｜ value （internal stress difference within two orientation）, roughness and exposure degree of iron grain after the same acid wash of black plate would enhance the corrosion resistance of T5 tinplate and the grain number of black plate has small effect on corrosion resistance of T5 tinplate.

基于Thevenin模型的蓄电池内阻监测装置的现场校验方法研究

蓄电池组在线监测系统在发电厂和变电站广泛应用,但其监测性能在交接验收和后期运行中缺乏行之有效的现场校准评价手段,导致运行中监测的有效性如何评价成为一个亟需解决的问题。文章基于Thevenin模型和GB/T 19638.1(IEC 60896-22 MOD)中的蓄电池内阻测量方法,提出了"标定电池+校验装置比对"的蓄电池组在线监测系统现场校验方法。通过该方法测得的标定电池内阻值与现场测量内阻值比率值E_(n)<0.191,符合ISO/IEC 17025标准要求。结果表明,该方法可对蓄电池组内阻值进行现场测试,实现对蓄电池组在线监测系统的在线校验,提高厂站用蓄电池组的运维管理水平。

Socio-Economic and Scientific Impact Created by Whitefly-Transmitted,Plant-Virus Disease Resistant Tomato Varieties in Southern India

Research carried out to assess the impact of open-pollinated Tomato leaf curl virus（ToLCV）-resistant tomatoes and hybrids on the livelihoods of resource-poor farmers in Southern India is described and discussed.Three high-yielding ToLCV-resistant tomato varieties were developed initially using conventional breeding and screening techniques involving inoculation by ToLCV-viruliferous whitefly,Bemisia tabaci.In 2003 and 2004,respectively,these varieties were released officially by the Karnataka State Seed Committee and the Indian Ministry of Agriculture through notification in the Gazette of India.From 2003 to 2005,eleven seed companies bought breeder seed of the ToLCV-resistant varieties and used them to begin breeding F1 hybrids from them.Socio-economic studies carried out to assess the benefits obtained from growing the ToLCV-resistant varieties found that farmers could gain up to 10 times the profit by growing the ToLCV-resistant varieties compared to the pre-existing ToLCV-susceptible varieties.Adoption of ToLCV-resistant tomatoes was also associated with reduced pesticide use.Extra income from tomato sales was prioritised by farmers to pay for children＇s education,better nutrition and medicines.In a joint effort with the commercial seed sector in India,a promotional field day was organised in 2007.As well as the three ToLCV-resistant varieties,62 ToLCV-resistant hybrid tomatoes were exhibited during a farmer-field day by 17 commercial seed companies and several public institutes.Tomatoes with ToLCV-resistance are now grown widely in South India and seeds of the three open-pollinated varieties have been distributed to more than 12 countries.In 2007,a conservative estimate of the financial-benefit to cost of the research ratio was already more than 837：1.

Data-driven short circuit resistance estimation in battery safety issues

Developing precise and fast methods for short circuit detection is crucial for preventing or mitigating the risk of safety issues of lithium-ion batteries(LIBs).In this paper,we developed a Convolutional Neural Networks(CNN)based model that can quickly and precisely predict the short circuit resistance of LIB cells during various working conditions.Cycling tests of cells with an external short circuit(ESC)are produced to obtain the database and generate the training/testing samples.The samples are sequences of voltage,current,charging capacity,charging energy,total charging capacity,total charging energy with a length of 120 s and frequency of 1 Hz,and their corresponding short circuit resistances.A big database with~6×10^(5)samples are generated,covering various short circuit resistances(47~470Ω),current loading modes(Constant current-constant voltage(CC-CV)and drive cycle),and electrochemical states(cycle numbers from 1 to 300).Results show that the average relative absolute error of five random sample splits is 6.75%±2.8%.Further parametric analysis indicates the accuracy estimation benefits from the appropriate model setups:the optimized input sequence length(~120 s),feature selection(at least one total capacity-related variable),and rational model design,using multiple layers with different kernel sizes.This work highlights the capabilities of machine learning algorithms and data-driven methodologies in real-time safety risk prediction for batteries.

喷涂距离对内孔HVOF喷涂纳米WC-10Co4Cr涂层组织及抗泥沙冲蚀性能的影响

利用内孔氧-丙烷超音速火焰喷涂技术在ZG0Cr13Ni5Mo不锈钢基材表面制备纳米WC-10Co4Cr涂层,分别通过45°和90°两种内孔喷枪研究了喷涂距离对涂层宏/微观组织及抗泥沙冲蚀性能的影响。采用X射线衍射仪(XRD)测试分析了涂层的物相成分,利用扫描电子显微镜(SEM)观察了涂层截面的微观形貌,并结合金相显微镜分析了孔隙率;通过维氏硬度计测试了涂层的显微硬度,利用粗糙度仪和光学轮廓仪表征了涂层表面的粗糙度及三维形貌;采用泥沙冲蚀磨损试验机对比研究了涂层与不锈钢基材的抗泥沙冲蚀性能,并结合SEM分析了冲蚀磨损机理。研究发现,45°和90°两种内孔喷枪所制备纳米WC-10Co4Cr涂层主要物相成分均为WC、W_(2)C和非晶态CoCr合金相,未受到喷涂距离的影响。短喷涂距离会导致涂层孔隙缺陷的产生,孔隙率随着喷涂距离的增大先下降后上升。喷涂距离对90°喷枪所制备涂层显微硬度的影响较小,而45°喷枪在喷涂距离增大到150 mm以后涂层硬度有下降趋势,两者最高硬度分别为1343.1 HV0.2和1275.4 HV0.2;对于两种喷枪,短喷涂距离会导致涂层表面产生凸起团聚颗粒,粗糙度随着喷涂距离的增大而降低。涂层抗泥沙冲蚀性能随喷涂距离的增大先升高而后逐渐下降,45°和90°内孔喷枪喷距分别为200 mm和250 mm时所制备涂层的抗泥沙冲蚀性能达到最高,分别是基材的7.03倍和8.05倍。WC-10Co4Cr涂层的泥沙冲蚀磨损机制主要是交变应力下的疲劳剥落,基材则为均匀的泥沙微切削。

骨折内固定术后感染金黄色葡萄球菌患者的耐药监测及临床分析

目的 分析金黄色葡萄球菌在骨折内固定术后感染患者中的耐药情况。方法 回顾性分析四川省骨科医院2016年1月至2020年12月骨折内固定术后确诊为金黄色葡萄球菌感染的临床病例,共收集金黄色葡萄球菌467株。根据药物敏感性实验分为耐甲氧西林金黄色葡萄球菌(MRSA)组(145株)和甲氧西林敏感金黄色葡萄球菌(MSSA)组(322株),分析比较2组对常见抗菌药物的耐药情况。统计2016—2020年万古霉素对MRSA最低抑菌浓度(MIC)。结果 金黄色葡萄球菌对青霉素的耐药率达94.9%(443/467),对红霉素、克林霉素、苯唑西林、四环素耐药率较高,对左氧氟沙星、利福平、复方磺胺甲噁唑片、莫西沙星的耐药率较低[8.4%(39/467)、5.8%(27/467)、3.6%(17/467)、3.0%(14/467)],未发现对万古霉素、利奈唑胺、达托霉素耐药的菌株,万古霉素中介3株。MRSA组和MSSA组对克林霉素、苯唑西林、红霉素、左氧氟沙星、莫西沙星、青霉素、利福平、复方磺胺甲噁唑片、四环素的耐药率比较差异均有统计学意义(均P<0.05)。万古霉素对MRSA的MIC为2 mg/L的比例较高。结论 金黄色葡菌球菌引起的骨折内固定术后感染MRSA检出率较高,万古霉素MIC=2 mg/L的比例较高,降低了万古霉素治疗骨折内固定术后感染的达标率,且万古霉素骨组织渗透率不高,增加了临床治疗难度。因此万古霉素骨水泥植入,联合万古霉素静脉用药,或万古霉素静脉用药与利福平、喹诺酮类、磺胺类、利奈唑胺等联合用药可能是治疗骨折内固定术后感染的较好选择。

抗战时期西北国际通道初探

西北国际通道是抗战时期经中国西北地区运输外国援华物资、援华人员和中国易货物资的重要国际通道,西北国际通道的开辟与运行对于中国抗日战争胜利发挥了极为重要的历史作用。学界对西北国际通道研究十分关注,现有研究对其基本概念如名称、路线、里程认识并不一致。文章依据通道地理位置及运输状况将其定名为西北国际通道;通过梳理抗战时期报纸、期刊、书籍等资料,分析得出通道有三条线路,公路线起自今哈萨克斯坦萨雷奥泽克车站,终于兰州,航空线为阿拉木图至兰州,驿运线为印度列城至中国新疆叶城;以修建维护通道的新疆公路局、西北公路局等机构资料为依据,考订西北国际通道公路线里程为2934公里。

国产SiC功率模块热阻测试方法研究

为解决国产SiC功率模块的热阻不能准确测试的问题,开展了非开关式电学法在线测量模块热阻的研究。提出模块热阻测试方案,设计搭建模块热阻测试平台,结合器件结构特点和工艺特点,研究获得适用于模块的热阻测试方法,并选用两款典型SiC功率模块进行了验证,验证了测试结果的准确性。

健脾化痰汤结合针刺治疗成人鼾症(痰湿内阻型)临床疗效观察

目的:观察健脾化痰汤结合针刺治疗成人鼾症(痰湿内阻型)临床效果。方法:将我院收治的105例成人鼾症(痰湿内阻型)患者(2019年5月~2022年6月)纳入本次研究,并以随机数字表法分为常规治疗组(52例)与中医治疗组(53例),常规治疗组患者进行常规方案治疗,中医治疗组患者采取健脾化痰汤结合针刺治疗,数据比较:临床疗效、治疗前后中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)变化及ESS嗜睡量表评分变化、两组治疗前后体质指数(BMI)及最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数变化、治疗满意度。结果:中医治疗组患者总有效率(96.23%)高于常规治疗组(84.62%),P<0.05;治疗前,各组患者中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)、ESS评分、BMI、最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数等指标比较,P>0.05,治疗后各组患者中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)、ESS评分、BMI、最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数等指标均改善,中医治疗组患者治疗后中医证候积分(夜寐不实、睡则打鼾、憋醒、形体肥胖等)、ESS评分、BMI、最低血氧饱和度、氧减指数、最长呼吸暂停时间以及睡眠呼吸暂停低通气指数等指标均优于常规治疗组,P<0.05;中医治疗组患者治疗满意率(96.23%)高于常规治疗组(82.69%),P<0.05。结论:健脾化痰汤结合针刺治疗成人鼾症(痰湿内阻型)临床效果显著,患者症状好转,恢复较好,患者较为认可,值得应用。

电学计量中的量子标准与自然常数

介绍了库仑定律和安培定律在电学单位制中发挥的作用,依据机械功率与电功率等效的原理,选择电流单位安培(A)作为基本物理单位,并介绍了实用单位制和电学实物计量标准。阐述了三种电学计量的量子标准原理和溯源到自然常数的途径,分析了真空磁导率在安培定律公式中发挥的作用,探讨了电学量子三角形与欧姆定律兼容的问题。指出基本电荷量常数不是简单地从约瑟夫森常数K_(J-90)和冯·克里青常数R_(H-90)推导而来,而是由精细结构常数公式计算出来的,能量守恒原理是单位制中的第一性原理,是力学和电学计量单位的纽带。提出量子点之间的位移电流对单电子隧道泵有一定的影响,真空磁导率不再是理想的常数,真空磁导率的变化将成为后来理论界研究的重点。