Modeling and forecasting exchange rate volatility in Bangladesh using GARCH models:a comparison based on normal and Student's t-error distribution

Background:Modeling exchange rate volatility has remained crucially important because of its diverse implications.This study aimed to address the issue of error distribution assumption in modeling and forecasting exchange rate volatility between the Bangladeshi taka(BDT)and the US dollar($).Methods:Using daily exchange rates for 7 years(January 1,2008,to April 30,2015),this study attempted to model dynamics following generalized autoregressive conditional heteroscedastic(GARCH),asymmetric power ARCH(APARCH),exponential generalized autoregressive conditional heteroscedstic(EGARCH),threshold generalized autoregressive conditional heteroscedstic(TGARCH),and integrated generalized autoregressive conditional heteroscedstic(IGARCH)processes under both normal and Student’s t-distribution assumptions for errors.Results and Conclusions:It was found that,in contrast with the normal distribution,the application of Student’s t-distribution for errors helped the models satisfy the diagnostic tests and show improved forecasting accuracy.With such error distribution for out-of-sample volatility forecasting,AR(2)–GARCH(1,1)is considered the best.

艾灸联合西药规范化治疗肺结核疗效观察及对外周血T淋巴细胞亚群变化的影响

目的:观察艾灸联合西药规范化治疗肺结核(PTB)的临床疗效及对外周血T淋巴细胞亚群变化的影响。方法:选择104例PTB患者作为研究对象,按随机数字表法分为观察组与对照组各52例。对照组给予西药规范化治疗(2HRZS/4HR标准化疗方案),观察组在对照组基础上联合艾灸辅助治疗。治疗6个月,比较2组临床疗效、病灶吸收率、痰菌转阴率、中医证候评分及外周血T淋巴细胞亚群(CD3^(+)、CD4^(+)、CD8^(+)、CD4^(+)/CD8^(+))水平变化。结果:观察组总有效率为94.23%,对照组为76.92%,2组比较,差异有统计学意义(P<0.05)。观察组病灶吸收有效率为90.38%,对照组为73.08%,2组比较,差异有统计学意义(P<0.05)。观察组痰菌转阴率为82.69%,对照组为61.54%,2组比较,差异有统计学意义(P<0.05)。治疗后,2组中医证候评分均较治疗前降低(P<0.05),且观察组中医证候评分低于对照组(P<0.05)。治疗后,2组CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)水平均较治疗前升高(P<0.05),且观察组CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)水平均高于对照组(P<0.05);2组CD8^(+)水平均较治疗前降低(P<0.05),且观察组CD8^(+)水平低于对照组(P<0.05)。结论:艾灸辅助2HRZE/4HR方案规范化治疗PTB疗效确切,可明显促进病灶吸收及痰菌转阴,有效改善其临床症状和免疫功能。

EFFECTS OF MEDICINAL MOXIBUSTION ON SERUM GASTRIN,URINARY D-XYLOSE EXCRETORY RATE AND T CELL SUBGROUPS IN SPLEEN DEFICIENCY PATIENTS

The medicinal moxa stick made by moxa wool combining with Chinese medicines of supporting the body resistance and strengthening the spleen was used to treat 74 cases of spleen deficiency, the other 41 patients as control were treated by pure moxa stick. After treatment, the serum gastrin, urinary D - xylose excretory rate and T cell subgroups in patients with spleen deficiency have been greatly improved as compared with those before treatment in two groups (P< 0.01 or 0.05). Comparing the changes of the indexes between treatment group and control group, there were significant(P<0.05), or markedly significant(P<0.01) differences. It indicated that the medicinal moxibustion could improve the secreting and absorbing functions of digestive tract and the cellular immune function in patients with spleen deficiency.

The effects of temperature and substrate on ontogenetic behavior of bastard halibut, Paralichthys olivaceus (T. et S.)

The effects of temperature and substrate on ontogenetic patterns and settlement behavior of bastard halibut, Paralichthys olivaceus (T. et S.) were studied in a series of laboratory experiments. Analysis on stage-based data revealed that except for settlement, and compared to the substrate, the ambient temperature dominantly controlled the hatch success and subsequent development of the species. The oosperm optimum survival rate of 60% during hatching occurred at 20℃, and survival rate of 29%, at 18℃ for larval rearing. The survival rate of larvae reared under variable temperature of 3.5–4.5℃ was higher than that of those reared under stable temperature. The maximum survival rate of 29%, corresponded to variation at temperature of 4℃. With increase in age newly settled juveniles preferred to lie on the fine substrate and gradually moved on the coarse substrate. GLM (general linear model) analysis showed that the combination of temperature and substrate had no significant impact on the survival of settling larvae, but definitely affected the duration of settlement.

Aqueous extract of Protaetia brevitarsis larvae increases mTOR-mediated growth rate in zebrafish larvae

Objective:To evaluate the effects of an aqueous extract of Protaetia brevitarsis(AEPB)on the growth of zebrafish and preosteoblast MC3T3-E1 cells.Methods:The effects of AEPB on the linear growth and the expression of growth-related genes in zebrafish and MC3T3-E1 cells were assessed using various molecular techniques.Furthermore,the involvement of the mammalian target of rapamycin(mTOR)pathway in AEPB-induced growth was investigated by employing the mTOR inhibitor rapamycin.Results:AEPB administration led to a significant and dose-dependent increase in zebrafish larvae growth over time.Additionally,AEPB treatment upregulated the expression of growth hormone-1(GH-1),insulin-like growth factor-1(IGF-1),growth hormone receptor-1(GHR-1),and cholecystokinin-a(CCKA)in zebrafish.Similarly,AEPB stimulated the expression and release of IGF-1 and accelerated mTOR expression in MC3T3-E1 cells.In addition,rapamycin hindered AEPB-induced linear growth in zebrafish larvae and suppressed the expression of growth-promoting genes by inhibiting mTOR activation.Conclusions:AEPB shows growth-promoting effects by upregulating growth-related genes and activating the mTOR signaling pathway.Further investigations are warranted to elucidate its mechanisms of action and explore its potential application in the development of growth-enhancing supplements for various purposes.

Probability estimation method for fatigue crack growth rate based on a∼t data from service

Purpose–The study aims to provide a basis for the effective use of safety-related information data and a quantitative assessment way for the occurrence probability of the safety risk such as the fatigue fracture of the key components.Design/methodology/approach–The fatigue crack growth rate is of dispersion,which is often used to accurately describe with probability density.In view of the external dispersion caused by the load,a simple and applicable probability expression of fatigue crack growth rate is adopted based on the fatigue growth theory.Considering the isolation among the pairs of crack length a and crack formation time t(a∼t data)obtained from same kind of structural parts,a statistical analysis approach of t distribution is proposed,which divides the crack length in several segments.Furthermore,according to the compatibility criterion of crack growth,that is,there is statistical development correspondence among a∼t data,the probability model of crack growth rate is established.Findings–The results show that the crack growth rate in the stable growth stage can be approximately expressed by the crack growth control curve da/dt=5 Q•a,and the probability density of the crack growth parameter Q represents the external dispersion;t follows two-parameter Weibull distribution in certain a values.Originality/value–The probability density f(Q)can be estimated by using the probability model of crack growth rate,and a calculation example shows that the estimation method is effective and practical.

调节性T细胞对腺样体肥大合并过敏性鼻炎患儿治疗后复发的预测价值

目的探讨调节性T(Treg)细胞与腺样体肥大合并过敏性鼻炎患儿糠酸莫米松治疗后复发的关系。方法选取2021年1月至2023年1月常州市妇幼保健院收治的104例腺样体肥大合并过敏性鼻炎患儿为研究对象,所有患儿进行1个月的糠酸莫米松治疗。根据停药3个月后是否复发,分为复发组和未复发组。分别检测两组患儿治疗前后的外周血Treg细胞、白细胞介素10(IL-10)、转化生长因子β1(TGF-β1)、IgE、IgG4水平和嗜酸性粒细胞计数(EOS),测定两组患儿停药3个月后腺样体/鼻咽腔(A/N)值和过敏性鼻炎症状积分。通过Pearson相关分析Treg细胞与A/N值、症状积分的相关性,以受试者工作特征(ROC)曲线评估Treg细胞、IL-10、TGF-β1、IgE、IgG4、EOS对复发情况的预测效能。结果104例腺样体肥大合并过敏性鼻炎患儿复发率为41.35%(43/104)。复发组治疗后的Treg细胞、IL-10、TGF-β1、IgG4均低于未复发组,而IgE、EOS、A/N值和症状积分均高于未复发组,差异均有统计学意义(P<0.05)。Pearson分析显示,Treg细胞与A/N值(r=-0.470,P<0.001)、鼻炎症状积分(r=-0.872,P<0.001)均为呈负相关。Treg细胞对患儿复发的预测准确度为94.6%,灵敏度为95.1%,特异度为93.0%。结论Treg细胞对腺样体肥大合并过敏性鼻炎患儿治疗预后情况有较高的预测效能。

锈蚀钢筋混凝土T梁的疲劳性能试验

为探明我国早期建造的公路钢筋混凝土T梁桥纵筋锈蚀后的疲劳性能,加工制作10根实际锈蚀率在4.12%~13.72%之间的钢筋混凝土T梁试件,对其开展疲劳应力比在0.25~0.67范围内的疲劳试验。试验结果表明:轻度锈蚀T梁试件的挠度、弯曲裂缝宽度和材料应变均呈现明显的前期快速发展-中期稳定变化-后期迅速增长的“三阶段发展”特征,疲劳破坏一般以弯曲裂缝超限为标志;中度或重度锈蚀T梁试件承受应力比小于0.30左右的疲劳荷载作用时,前者中期平稳发展阶段基本消失,后者甚至会发生低周疲劳破坏;当应力比不超过0.31时,中度和重度锈蚀试件相比轻度锈蚀试件的疲劳寿命分别减小了约48%和71%;当应力比从0.66减小到0.31时,中度和重度锈蚀试件的疲劳寿命分别减小了约85%和90%。由于中度或重度锈蚀的公路钢筋混凝土T梁的实际疲劳寿命远低于200万次的设计疲劳寿命,故设计和运维中应采取措施减小主筋锈蚀率及疲劳应力幅值。

GB/T 10561—2023在焊管用钢夹杂物分析中的使用探讨

针对GB/T 10561—2023标准,从焊管用钢中非金属夹杂物的取样方法和取样数量、试样观察和级别评定、结果表示与试验报告出具等方面进行了介绍,特别对该标准中球状颗粒的最大直径新增定义、串(条)状夹杂物横向中心间距的增大调整、评级图级别最大值增大调整、细系和粗系结果表示方法变化、复合夹杂物和析出相的评定增加实例等方面的修订变化进行了说明,并对制管企业的标准执行提出了建议,以便于更好地运用新版标准内容以及进行夹杂物含量测定的实际操作。

驱梅汤联合多西环素对梅毒患者免疫炎症反应及外周血单核细胞TLR2、Foxp3 mRNA的影响

目的探讨驱梅汤联合多西环素对梅毒患者免疫炎症反应及外周血单核细胞(PBMCs)Toll样受体2(TLR2)、叉头框蛋白3(Foxp3)mRNA水平的影响。方法选取2016年12月至2020年12月邢台市第二医院收治的107例梅毒患者作为研究对象。采用随机信封法分为常规组(n=53)和实验组(n=54)。常规组采用多西环素治疗,实验组采用多西环素联合驱梅汤治疗。比较两组梅毒滴度快速血浆反应素试验(RPR)转阴率、临床疗效、T淋巴细胞亚群(CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+))、PBMCs TLR2、Foxp3 mRNA相对表达量及不良反应发生情况。结果实验组治疗后3、6个月RPR转阴率高于常规组(P<0.05);实验组总有效率高于常规组(P<0.05);治疗30 d后实验组CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)高于常规组(P<0.05);治疗30 d后实验组PBMCs TLR2、Foxp3 mRNA相对表达量低于常规组(P<0.05);实验组不良反应发生率低于常规组(P<0.05)。结论驱梅汤联合多西环素治疗梅毒患者能提高转阴率,疗效确切,且安全性较高,这可能与抑制PBMCs TLR2、Foxp3 mRNA表达有关。

High Dose Rate (HDR) Brachytherapy for Mycosis Fungoides of the Wrist

Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma accounting for approximately half of all cutaneous T-cell lymphomas. Radiation therapy is an effective treatment for early stage MF and has been shown to result in long-term disease-free intervals, with even curative potential. Radiation is also effective as palliative treatment for the localized lesion resistant to the topic or other treatments. In the current study, we report using high dose rate (HDR) radiation treatment for a patient with resistant mycosis fungoides involving the wrist. We report a convenient treatment with an ideal radiation dose distribution, and a excellent clinical outcome.

Do States with Professional Sports Teams Have Lower Suicide Rates?

The author examines six age-group specific suicide rates in 2016 between states (in the continental United States) with and without professional sports teams in baseball [MLB], football [NFL], hockey [NHL], and basketball [NBA]. States with at least one team in baseball or football have significantly lower suicide rates among adults in all six age groups (over 20 years of age). States with at least one hockey team have significantly lower suicide rates for all adults over the age of 20, except the oldest age group (adults 65 years of age or over). The results are weakest for states with at least one basketball team. Adults only between 25 and 44 years of age and 65 years of age or over have significantly lower suicide rates with at least one NBA team.

GB/T 10561—2023钢中非金属夹杂物标准简析

介绍了新旧版GB/T 10561《钢中非金属夹杂物含量的测定标准评级图显微检验法》标准的主要变化以及与ISO 4967:2013等标准的主要差异,对比发现,新版GB/T 10561—2023借鉴了ASTM E45-18a(2023)《钢中夹杂物含量测定的标准试验方法》的一些好的做法。此次修订对于复合夹杂物、析出相、夹杂物级别等方面有了更加清晰的说明外,还将旧版标准资料性附录中的制取样等移入标准正文。此外增加了3.5~5.0级夹杂物的总长度数值,但未给出该级别范围的评级图,还修改了结果表示等内容,在使用时应予以注意。

T型三通管中液固两相流冲蚀规律的研究

在输送流体的过程中,管道介质所携带的一些微小固体颗粒,会对管道壁面造成冲蚀磨损甚至发生穿孔现象,进而造成管道泄漏。本文采用流体动力学方法,运用DPM冲蚀预测模型,研究了固体颗粒速度、颗粒直径、含砂率对T型三通管冲蚀速率的影响,分析了冲蚀磨损规律,以确定管道中冲蚀磨损最严重的部位。结果表明,流体速度越大,含砂率越大,最大冲蚀速率越大,对管道壁面造成的冲蚀磨损越严重。T型三通管发生腐蚀最严重的部位是竖直管道与水平管道的交汇处。

新预后积分系统对血管免疫母细胞性T细胞淋巴瘤的预后评估意义

目的探讨血管免疫母细胞性T细胞淋巴瘤(AITL)的临床特征和预后影响因素,比较几种预后分层模型对其预后的评估价值。方法回顾性分析79例AITL患者的临床资料,采用国际预后指数(IPI)、外周T细胞淋巴瘤预后指数(PIT)、AITL预后指数(PIAI)评分及新建立的预后积分系统对患者进行危险分层。采用Kaplan-Meier法及Cox回归模型进行生存及预后分析,受试者工作特征(ROC)曲线比较不同预后积分系统的预测价值。结果AITL患者的中位发病年龄为66(29~83)岁。可评估疗效的73例患者中,获得完全缓解27例(37.0%),部分缓解20例(27.4%),总体缓解率为64.4%。中位总生存期(OS)为17(1.0~107.0)个月,3年和5年生存率分别39.76%和26.51%,3年和5年无进展生存率分别为23.58%和17.33%。基于多因素分析不良预后因素为年龄>65岁、ECOG评分>1分、C-反应蛋白(CRP)>20 mg/L和预后营养指数(PNI)<44.35,建立一种新的预后积分系统,其在甄别低危及中低危、中高危及高危患者方面优于IPI、PIT、PIAI评分。在预测AITL患者OS和无进展生存期(PFS)的ROC曲线中,新预后积分系统的AUC分别为0.8259(95%CI 0.7157~0.9361)和0.8592(95%CI 0.7513~0.9670)。结论AITL好发于高龄老年人,初诊时多为Ⅲ-Ⅳ期,疾病进展快,疗效及预后较差。与IPI、PIT及PIAI评分相比,基于年龄>65岁、ECOG评分>1分、CRP>20 mg/L和PNI<44.35所建立的新预后积分系统预后评估价值更高,更有助于识别高危患者。

结核感染T细胞γ干扰素释放试验及结核杆菌抗体在肺结核患者诊断中的应用

目的:探讨对结核感染T细胞γ干扰素释放试验(TB-IGRA)及结核杆菌抗体(TB-Ab)在肺结核患者诊断中的应用价值。方法:选择2022年1—12月荆州市第三人民医院收治的216例疑似肺结核患者,将病理学诊断作为“金标准”,依据是否存在结核病进行分组,分为肺结核组(n=151)和非肺结核组(n=65),采集患者清晨空腹静脉血分别检测TB-IGRA、TB-Ab水平,观察两项指标检测肺结核阳性结果,观察不同检查方式诊断效能。结果:肺结核组中TB-IGRA阳性检出率、TB-Ab阳性检出率均高于非肺结核组,差异有统计学意义(P<0.05)。TB-IGRA、TB-Ab诊断肺结核的阳性预测值、特异度比较,差异无统计学意义(P>0.05),TB-IGRA诊断肺结核的敏感度、阴性预测值高于TB-Ab,差异有统计学意义(P<0.05)。年龄>60岁肺结核患者TB-IGRA阳性检出率、TB-Ab阳性检出率高于≤60岁肺结核患者,差异有统计学意义(P<0.05)。结论:临床肺结核诊断中应用TB-IGRA、TB-Ab检查均有较高诊断效能,但相对而言TB-IGRA检查方式更优,且该检查方式阳性率易受年龄因素影响。

烟气分析在120 t转炉的应用

利用转炉烟气分析系统获取烟气成分与流量数据,依据碳平衡原理构建碳积分模型,动态预测钢水中的碳含量(质量分数)及温度。该模型在陕西龙门钢铁有限公司的120 t转炉上得到应用,有效指导了转炉冶炼过程,减少了终点补吹次数,并降低了一次脱磷率。研究结果表明,模型显示出良好的适应性与高准确度,对于该公司120 t转炉的冶炼生产起到了重要的指导作用。在排除了铁水成分、温度测量异常以及废钢重量异常等因素影响的有效炉次中,当终点碳含量w(C)<0.2%时,该模型预测的偏差<0.02%,准确率达到86.38%。当终点温度预测的偏差<15℃时,准确率高达94.42%。同时,满足碳含量与温度预测准确的C-T双命中率为81.49%,达到了冶炼过程对终点命中率的要求。

动态心电图联合心率变异参数定量在诊断心电图ST-T改变中的价值

目的探究动态心电图联合心率变异参数在诊断心电图ST-T改变中的应用价值。方法选择2020年7月—2023年4月于陕西省森林工业职工医院接受体格检查的170人作为研究对象,对入组研究对象均开展心电图检查,按照其检测结果是否存在ST-T改变分为研究组(n=85,存在心电图ST-T改变)和对照组(n=85,无心电图ST-T改变),分别对两组实施动态心电图检测,记录其心率变异性中定量参数相邻NN间期差值>50 ms研究对象所占的百分比(PNN50)、相邻NN间期差值的均方根(RMSSD)、所有窦性心律RR间期标准差(SDNN)后进行比较,通过绘制ROC曲线的方式判断动态心电图、心率变异定量参数以及联合检测对心电图ST-T诊断的价值。结果研究组动态心电图中的室上早及室上速均显著高于对照组,差异有统计学意义(P<0.05);动态心电图指标室上早和室上速对心电图ST-T改变的诊断AUC分别为0.873、0.856,诊断灵敏度为81.18%,特异度为76.65%,提示数据的一致性良好;研究组心率变异参数中的SDNN、RMSSD以及PNN50均显著高于对照组,差异有统计学意义(P<0.05);心率变异参数SDNN、RMSSD以及PNN50对心电图ST-T改变的诊断AUC分别为0.845、0.622、0.799,诊断灵敏度为83.53%、61.18%、74.12%,特异度为81.18%、52.95%、70.59%,提示SDNN、PNN50对心电图ST-T改变的诊断的一致性良好,而RMSSD有较低的一致性;采用串联方式,计算显示,动态心电图联合心率变异参数对心电图ST-T改变诊断的一致性为95.88%,灵敏度为98.82%,特异度为92.94%。结论心电图ST-T改变患者的动态心电图参数及心率变异参数均会出现明显改变,将上述定量参数应用于心电图ST-T改变诊断中存在较好的临床效能,具有一定的临床应用价值。

机械取栓治疗对急性颈内动脉末端T形闭塞患者血管再通率和临床预后的影响研究

分析机械取栓治疗对急性颈内动脉末端T形闭塞患者血管再通率和临床预后的影响。选择黔南州人民医院2021年5月—2023年5月收治的40例急性颈内动脉末端T形闭塞患者为研究对象,采用抽签法将患者分为比对组(n=20,采取单纯支架取栓治疗)和试验组(n=20,采取支架联合中间导管抽吸取栓治疗),比较两组患者治疗效果。结果显示,试验组患者穿刺到再通时间短于比对组(P<0.05);试验组出院时神经功能评分低于比对组(P<0.05);试验组患者血管再通率、90天良好预后率高于比对组,症状性颅内出血率低于比对组(P<0.05);试验组患者各项生活质量评分均高于比对组(P<0.05)。研究发现,临床上针对急性颈内动脉末端T形闭塞患者采用支架联合中间导管抽吸取栓治疗,血管再通率高,患者的预后较好,神经功能损伤较低,可提高患者的生活质量。

t-BAMBP萃取分离高钾钠卤水中的铷工艺研究

以二甲苯为稀释剂的t-BAMBP萃取体系,从高钾钠卤水中萃取分离铷.研究有机相配比、料液碱度、相比、萃取时间及萃取温度对萃取分离铷效果的影响.结果表明:在有机相组成(体积分数)为30%t-BAMBP+70%二甲苯,料液Rb+初始浓度为0.011 7 mol/L,料液碱度为0.4 mol/L,相比VO/VA(有机相体积比水相体积)为1/1,萃取时间为4 min,萃取温度为21℃的条件下,经过五级逆流萃取,铷萃取率达95.5%.通过对料液进行多段萃取处理,可获得高纯度的铷盐.