Comparative study of various methods for extraction of multi-quantum wells Schottky diode parameters

In this work,forward current voltage characteristics for multi-quantum wells Al_(0.33)Ga_(0.67)As Schottky diode were measured at temperature ranges from 100 to 300 K.The main parameters of this Schottky diode,such as the ideality factor,barrier height,series resistance and saturation current,have been extracted using both analytical and heuristics methods.Differential evolution(DE),particle swarm optimization(PSO)and artificial bee colony(ABC)have been chosen as candidate heuristics algorithms,while Cheung technic was selected as analytical extraction method.The obtained results show clearly the high performance of DE algorithms in terms of parameters accuracy,convergence speed and robustness.

Visualizing light-to-electricity conversion process in InGaN/GaN multi-quantum wells with a p-n junction

Absorption and carrier transport behavior plays an important role in the light-to-electricity conversion process, which is difficult to characterize. Here we develop a method to visualize such a conversion process in the InGaN/GaN multiquantum wells embedded in a p-n junction. Under non-resonant absorption conditions, a photocurrent was generated and the photoluminescence intensity decayed by more than 70% when the p-n junction out-circuit was switched from open to short. However, when the excitation photon energy decreased to the resonant absorption edge, the photocurrent dropped drastically and the photoluminescence under open and short circuit conditions showed similar intensity. These results indicate that the escaping of the photo-generated carriers from the quantum wells is closely related to the excitation photon energy.

Effects of polarization on intersubband transitions of Al_xGa_(1-x)N/GaN multi-quantum wells

The effects of polarization and related structural parameters on the intersubband transitions of A1GaN/GaN multi- quantum wells （MQWs） have been investigated by solving the Schr6dinger and the Poisson equations self-consistently. The results show that the intersubband absorption coefficient increases with increasing polarization while the transition wavelength decreases, which is not identical to the case of the interband transitions. Moreover, it suggests that the well width has a greater effect on the intersubband transitions than the barrier thickness, and the intersubband transition wavelength of the structure when doped in the barrier is shorter than that when doped in the well. It is found that the influences of the structural parameters differ for different electron subbands. The mechanisms responsible for these effects have been investigated in detail.

D-二聚体联合Wells评分对恶性肿瘤患者合并急性肺栓塞的诊断价值

目的评估D-二聚体联合Wells评分对恶性肿瘤患者合并急性肺栓塞(APE)的诊断价值。方法选取2020年9月至2022年6月天津市人民医院收治的恶性肿瘤可疑APE患者60例,根据CT肺动脉造影检查结果将入选患者分为APE组(33例)和非APE组(27例)。对比两组患者间的临床特点,比较D-二聚体、Wells评分、D-二聚体联合Wells评分对恶性肿瘤合并APE的诊断价值。结果D-二聚体诊断恶性肿瘤合并APE的敏感度为81.8%、特异度为63.0%[受试者操作特征曲线下面积(AUC)=0.730,95%CI 0.601~0.858,Z=3.463,P=0.0005],Wells评分的敏感度为48.5%、特异度为92.6%(AUC=0.678,95%CI 0.542~0.814,Z=2.630,P=0.0085),D-二聚体联合Wells评分的敏感度为69.7%、特异度为74.1%(AUC=0.756,95%CI 0.635~0.878,Z=4.104,P<0.0001)。结论D-二聚体联合Wells评分对恶性肿瘤患者合并APE具有诊断价值。

Nanoscale cathodoluminescence spectroscopy probing the nitride quantum wells in an electron microscope

To gain further understanding of the luminescence properties of multiquantum wells and the factors affecting them on a microscopic level,cathodoluminescence combined with scanning transmission electron microscopy and spectroscopy was used to measure the luminescence of In_(0.15)Ga_(0.85)N five-period multiquantum wells.The lattice-composition-energy relationship was established with the help of energy-dispersive x-ray spectroscopy,and the bandgaps of In_(0.15)Ga_(0.85)N and GaN in multiple quantum wells were extracted by electron energy loss spectroscopy to understand the features of cathodoluminescence spectra.The luminescence differences between different periods of multiquantum wells and the effects of defects such as composition fluctuation and dislocations on the luminescence of multiple quantum wells were revealed.Our study establishing the direct relationship between the atomic structure of In_(x)Ga_(1-x)N multiquantum wells and photoelectric properties provides useful information for nitride applications.

血清白细胞表面分化抗原40配体联合Wells评分对产褥期深静脉血栓的诊断价值及其与凝血、血小板功能及炎症指标的相关性

目的探讨血清白细胞表面分化抗原40配体(CD40 ligand,CD40L)联合Wells评分对产褥期深静脉血栓(deep vein thrombosis,DVT)的诊断价值及其与凝血、血小板功能及炎症指标的相关性。方法选取2013年8月至2023年7月秦皇岛市妇幼保健院收治的107例产褥期DVT患者作为研究对象,设为DVT组。选取同期在秦皇岛市妇幼保健院分娩的健康产妇100例作为对照组。比较两组基本资料、血清CD40L、Wells评分及凝血、血小板功能及炎症指标,进行Pearson相关性分析,并采用受试者操作特征(receiver operating characteristic,ROC)曲线评价CD40L、Wells评分对产褥期DVT的诊断价值。结果两组研究对象的基本资料差异无统计学意义(均P>0.05)。相比于对照组,DVT组血清CD40L、Wells评分、凝血指标[D-二聚体(D-dimer,D-D)、纤维蛋白原(fibrinogen,FIB)]、血小板功能指标[血小板黏附率(platelet adhesion rate,PAdT)、血小板聚集率(platelet aggregation rate,PAgT)、P选择素(P-selection)]、炎症因子[白细胞介素-6(interleukin-6,IL-6)/IL-1β、高敏C反应蛋白(high-sensitivity c-reactive protein,hs-CRP)]更高(P<0.05),凝血指标(凝血酶原活化时间、凝血酶原时间)更低(P<0.05)。经过Pearson相关性分析,D-D、FIB、PAdT、PAgT、P-selection、IL-6、IL-1β、hs-CRP与产褥期VTE患者血清CD40L、Wells评分均呈正相关(P<0.05),APTT、PT与血清CD40L、Wells评分呈负相关(P<0.05)。ROC曲线显示,血清CD40L联合Wells评分诊断产褥期DVT的AUC、敏感度均显著高于各指标单独诊断(P<0.05)。结论血清CD40L联合Wells评分可提高产褥期DVT的诊断效能,有利于疾病的早期确诊,并及时采取治疗措施。

Reanalysis of energy band structure in the type-II quantum wells

Band structure analysis holds significant importance for understanding the optoelectronic characteristics of semiconductor structures and exploring their potential applications in practice. For quantum well structures, the energy of carriers in the well splits into discrete energy levels due to the confinement of barriers in the growth direction. However, the discrete energy levels obtained at a fixed wave vector cannot accurately reflect the actual energy band structure. In this work, the band structure of the type-II quantum wells is reanalyzed. When the wave vectors of the entire Brillouin region(corresponding to the growth direction) are taken into account, the quantized energy levels of the carriers in the well are replaced by subbands with certain energy distributions. This new understanding of the energy bands of low-dimensional structures not only helps us to have a deeper cognition of the structure, but also may overturn many viewpoints in traditional band theories and serve as supplementary to the band theory of low-dimensional systems.

微小RNA物质、血栓标志物、Wells评分系统联合预测高龄髋部骨折DVT风险价值

目的探究微小RNA物质、血栓标志物、下肢深静脉栓塞评分(Wells评分)系统联合对高龄髋部骨折深静脉血栓形成(DVT)风险的预测价值,为减少DVT发生提供诊断依据。方法选取2020年10月—2022年10月我院收治的105例高龄髋部骨折患者,根据术后1周是否发生DVT分为DVT组(34例)、未DVT组(71例)。比较两组临床资料,于入院后术前进行Wells评分评估,并检测两组微小RNA物质[微小RNA-374b-5p(miR-374b-5p)、微小RNA-664b-3p(miR-664b-3p)]、血栓标志物[凝血酶-抗凝血酶复合物(TAT)、可溶性血栓调节蛋白(sTM)、纤溶酶α2抗纤溶酶复合物(PIC)、组织型纤溶酶原激活物-抑制剂复合物(t-PAIC)],分析DVT发生的影响因素,通过受试者工作特征曲线(ROC)、决策曲线分析(DCA)Wells评分、miR-374b-5p、miR-664b-3p、sTM、PIc、TAT、t-PAIC联合对高龄髋部骨折DVT风险的预测价值及临床效用。结果DVT组术前血浆FDP水平及Wells评分高度可能占比高于未DVT组(P<0.05);DVT组miR-374b-5p相对表达量高于未DVT组,miR-664b-3p相对表达量低于未DVT组(P<0.05);DVT组血浆sTM、PIC、TAT、t-PAIC水平均高于未DVT组(P<0.05);FDP、Wells评分、miR-374b-5p、miR-664b-3p、sTM、PIC、TAT、t-PAIC均为高龄髋部骨折患者发生DVT的影响因素(P<0.05);Wells评分、miR-374b-5p、miR-664b-3p、sTM、PIC、TAT、t-PAIC预测高龄髋部骨折DVT风险的AUC值分别为0.666、0.734、0.750、0.730、0.764、0.761、0.800,各指标联合预测高龄髋部骨折患者发生DVT的AUC最大,为0.921,且具有良好临床效用(P<0.05)。结论miR-374b-5p、miR-664b-3p、sTM、PIC、TAT、t-PAIC、Wells评分系统联合预测高龄髋部骨折DVT风险的预测效能较高,临床效用良好。

血清同型半胱氨酸检测联合Wells评分对慢性阻塞性肺疾病急性加重期患者发生静脉血栓栓塞症的预测价值研究

目的探究血清同型半胱氨酸(Hcy)检测联合Wells评分对慢性阻塞性肺疾病急性加重期患者发生静脉血栓栓塞症(VTE)的预测价值。方法选取2021年4月-2023年4月我院收治的94例慢性阻塞性肺疾病急性加重期患者,根据是否发生VTE分为VTE组20例和非VTE组74例。采用酶联免疫吸附测定(ELISA)法检测血清中Hcy水平。对全部患者进行Wells评分。Spearman相关性分析Hcy表达水平与Wells评分的关系;ROC曲线分析血清Hcy检测联合Wells评分对慢性阻塞性肺疾病急性加重期患者发生VTE的预测价值;Logistic回归分析影响慢性阻塞性肺疾病急性加重期患者VTE发生的因素。结果与非VTE组相比,VTE组患者C-反应蛋白(CRP)、D-二聚体(D-D)、Hcy水平以及Wells评分水平显著升高,动脉血氧分压(PaO_(2))水平显著降低(P<0.05)。Pearson相关性分析显示,慢性阻塞性肺疾病急性加重期患者Hcy表达水平与Wells评分呈正相关关系(r=0.491,P<0.05)。二者联合预测慢性阻塞性肺疾病急性加重期患者发生VTE的AUC高于血清Hcy表达水平与Wells评分单独预测的AUC值(Z=5.303,P<0.001;Z=9.151,P<0.001)。Logistic回归分析结果显示Hcy、Wells评分为VTE发生的影响因素(P<0.05)。结论慢性阻塞性肺疾病急性加重期发生VTE患者血清Hcy水平和Wells评分显著上升,二者联合检测对慢性阻塞性肺疾病急性加重期发生VTE的预测价值优于单一指标检测。

Study on the Impact of Massive Refracturing on the Fracture Network in Tight Oil Reservoir Horizontal Wells

Class III tight oil reservoirs have low porosity and permeability,which are often responsible for low production rates and limited recovery.Extensive repeated fracturing is a well-known technique to fix some of these issues.With such methods,existing fractures are refractured,and/or new fractures are created to facilitate communication with natural fractures.This study explored how different refracturing methods affect horizontal well fracture networks,with a special focus on morphology and related fluid flow changes.In particular,the study relied on the unconventional fracture model(UFM).The evolution of fracture morphology and flow field after the initial fracturing were analyzed accordingly.The simulation results indicated that increased formation energy and reduced reservoir stress differences can promote fracture expansion.It was shown that the length of the fracture network,the width of the fracture network,and the complexity of the fracture can be improved,the oil drainage area can be increased,the distance of oil and gas seepage can be reduced,and the production of a single well can be significantly increased.

Physico−mathematical model of the voltage−current characteristics of light-emitting diodes with quantum wells based on the Sah−Noyce−Shockley recombination mechanism

Herein,a physical and mathematical model of the voltage−current characteristics of a p−n heterostructure with quantum wells(QWs)is prepared using the Sah−Noyce−Shockley(SNS)recombination mechanism to show the SNS recombination rate of the correction function of the distribution of QWs in the space charge region of diode configuration.A comparison of the model voltage−current characteristics(VCCs)with the experimental ones reveals their adequacy.The technological parameters of the structure of the VCC model are determined experimentally using a nondestructive capacitive approach for determining the impurity distribution profile in the active region of the diode structure with a profile depth resolution of up to 10Å.The correction function in the expression of the recombination rate shows the possibility of determining the derivative of the VCCs of structures with QWs with a nonideality factor of up to 4.

Optical absorption via intersubband transition of electrons in GaAs/Al_xGa_(1-x)As multi-quantum wells in an electric field

Based on the effective mass approximation, the Schrodinger equation and Poisson equation in GaAs/AlGaAs multi-quantum wells(MQWs) are self-consistently solved to obtain the wave functions and energy levels of electrons in the conduction band for the ground first excited state by considering a lateral electric field(LEF). Then, the effects of size, ternary mixed crystal, doping concentration, and temperature on linear and nonlinear intersubband optical absorption coefficients(IOACs), and refractive index changes(RICs) due to the transition between ground states and the first excited states of electrons are discussed based on Fermi’s golden rule. The results show that, under a fixed LEF, with increase of A1 composition and doping concentration, the IOACs produce a red shift. With increases of both widths of the wells and barriers IOACs appear as blue shifts and their amplitudes increase, but the barrier width change is much more important to affect nonlinear IOACs, whereas increasing the temperature results in a blue shift first and then a red shift of IOACs. When the other parameters are fixed but there is an increase in the LEF, IOACs occur with a blue shift, and the RICs have similar properties.

Wells评分联合D-二聚体水平对重症肺血栓栓塞患者近期预后不良的预测分析

目的分析Wells评分联合血浆D-二聚体(D-D)水平对重症肺血栓栓塞(PTE)患者近期预后不良的预测价值。方法选取2016年1月—2020年11月江苏省人民医院收治的127例重症PTE患者,均随访至出院后6个月,根据近期预后将其分为预后良好组与预后不良。对比两组Wells评分、血浆D-D水平,比较出院护理满意度;采用多因素Logistic回归性分析法分析重症PTE患者近期预后不良的影响因素;以受试者工作特征(ROC)曲线评估Wells评分与血浆D-D水平对重症PTE患者近期预后不良的预测作用。结果127例重症PTE患者Wells评分为6~9(8.01±1.16)分,血浆D-D水平为7.65~8.88(8.35±0.66)μg/mL;经Pearson相关系数分析,患者Wells评分、血浆D-D水平均与肺栓塞严重程度指数(PESI评分)呈正相关(r=0.825、0.613,P<0.05);近期预后不良率为25.20%;预后良好组Wells评分、血浆D-D水平均显著低于预后不良组(P<0.05),两组出院护理满意度无差异(P>0.05);经多因素Logistic回归分析,PESI评分、B型钠尿肽(BNP)、Wells评分、血浆D-D均是重症PTE患者预后不良的危险因素(P<0.05);Wells评分联合血浆D-D水平联合预测重症PTE患者近期预后不良的灵敏度、曲线下面积(AUC)均高于单独预测(P<0.01)。结论重症PTE近期预后不良者Wells评分及血浆D-D水平均显著高于预后良好者,此二项指标均与患者近期预后不良关系密切,并均对患者近期预后不良具有一定的预测价值,但二者联合应用时的预测价值更高,可作为临床评估重症PTE患者近期预后的重要指标。

急诊中不明原因的呼吸困难患者应用Wells评分及D-二聚体变化对肺栓塞的诊断和风险评估的价值分析

目的探究急诊中不明原因的呼吸困难患者应用Wells评分及D-二聚体(D-D)对肺栓塞的诊断和风险评估的价值。方法纳入2019年1月至2021年7月因不明原因呼吸困难到诸暨市人民医院就诊的74例急性肺栓塞患者、91例非肺栓塞患者为研究对象,分析Wells评分及D-D水平变化对肺栓塞的诊断价值及对预后的预测价值。结果Wells评分及D-D水平联合检测诊断肺栓塞及预测患者预后的AUC均>0.85,D-D≥534.40μg/L是影响急性肺栓塞预后的危险因素(P<0.05)。结论Wells评分及D-D水平检测对肺栓塞具有诊断价值,对肺栓塞患者死亡风险有一定的预测价值。

Tp-Te间期、D-二聚体、简化的Wells评分对肺栓塞的诊断价值

目的:探讨Tp-Te间期、D-二聚体、简化的Wells评分对肺栓塞的预测价值,以期发现更适合临床疑诊肺栓塞的评估模型。方法:回顾性分析2021年6月-2022年9月于随州市中心医院就诊的可疑肺栓塞患者69例。以CT肺动脉血管成像作为诊断金标准,分为肺栓塞组与对照组。收集所有患者详细资料,完成常规心电图、D-二聚体检测。记录心电图一般指标及胸导联QT间期、Tp-Te间期,完成Wells评分。比较Tp-Te间期、D-二聚体、Wells评分对肺栓塞的预测价值。结果:心电图V1导联诊断价值最高;V1导联Tp-Te间期、D-二聚体、简化的Wells评分联合诊断与单一手段相比差异有统计学意义(P<0.05);D-二聚体≥0.5 mg/L联合简化Wells评分优势比最高(8.05)。结论:Tp-Te间期、D-二聚体、简化的Wells评分可用于肺栓塞早期评估。

D-D、Fib联合WELLS评分对下肢骨折术后深静脉血栓形成的预测价值

目的探讨D-二聚体(D-D)、纤维蛋白原(Fib)联合WELLS评分对下肢骨折术后深静脉血栓形成(DVT)的预测价值。方法选取2020年1月至2022年1月陆军第七十三集团军医院收治的80例下肢骨折术后患者为研究对象,根据下肢血管超声检查结果[是否形成DVT]分为DVT组(n=17)和非DVT组(n=63),比较两组一般资料、凝血功能指标[活化部分凝血活酶时间(APTT)、凝血酶原时间(PT)、国际标准化比值(INR)、D-D、Fib]及WELLS评分,采用多因素logistic回归分析下肢骨折术后患者发生DVT的独立影响因素,并通过受试工作者特征(ROC)曲线分析D-D、Fib、WELLS评分及三者联合预测DVT的价值。结果DVT组PT、INR、D-D、Fib水平及WELLS评分显著高于非DVT组,差异有统计学意义(P<0.05);两组APTT水平比较,差异无统计学意义(P>0.05)。多因素logistic回归分析显示,D-D、Fib、WELLS评分是发生DVT的独立危险因素(P<0.05)。D-D、Fib、WELLS评分及三者联合诊断DVT的曲线下面积(AUC)分别为0.831、0.793、0.872、0.974,三者联合诊断DVT的效能高于单一指标(P<0.05)。结论D-D、Fib联合WELLS评分可以提高下肢骨折术后DVT发生的预测价值,值得临床推广应用。

Subsection and superposition method for reservoir formation damage evaluation of complex-structure wells

Kinds of complex-structure wells can effectively improve production,which are widely used.However,in the process of drilling and completion,complex-structure wells with long drilling cycle and large exposed area of reservoir can lead to the fact that reservoir near wellbore is more vulnerable to the working fluid invasion,resulting in more serious formation damage.In order to quantitatively describe the reservoir formation damage in the construction of complex-structure well,taking the inclined well section as the research object,the coordinate transformation method and conformal transformation method are given according to the flow characteristics of reservoir near wellbore in anisotropic reservoir.Then the local skin factor in orthogonal plane of wellbore is deduced.Considering the un-even distribution of local skin factor along the wellbore,the oscillation decreasing model and empirical equation model of damage zone radius distribution along the wellbore direction are established and then the total skin factor model of the whole well is superimposed to realize the reservoir damage evaluation of complex-structure wells.Combining the skin factor model with the production model,the production of complex-structure wells can be predicted more accurately.The two field application cases show that the accuracy of the model can be more than 90%,which can also fully reflect the invasion characteristics of drilling and completion fluid in any well section of complex-structure wells in anisotropic reservoir,so as to further provide guidance for the scientific establish-ment of reservoir production system.

简化Wells评分、修订版Geneva评分和4PEPS评分对肺栓塞的诊断价值

目的探讨传统临床评分模型(简化Wells评分、修订版Geneva评分)及其联合D-二聚体对肺栓塞(PE)的诊断价值,并与新提出的4PEPS评分相对比。方法回顾分析2020年5月至2022年5月山西省人民医院收治的疑似PE患者219人,以CT肺血管造影(CTPA)结果为金标准,将患者分为PE组和非PE组,并利用临床评分模型进行评分,分析简化Wells评分、修订版Geneva评分及其联合D-二聚体、4PEPS评分预测PE的效果。结果219例患者中CTPA确诊为PE的79例,简化Wells评分、修订版Geneva评分及其联合D-二聚体、4PEPS诊断PE的敏感度分别为62.0%、55.7%、55.7%、49.4%、68.4%;特异度分别为78.6%、71.4%、85.0%、80.7%、68.6%;准确度分别为72.6%、65.8%、74.4%、69.4%、68.5%;Youden指数分别为0.41、0.27、0.41、0.30、0.37;Kappa值分别为0.406、0.268、0.423、0.312、0.312;AUC分别为0.735、0.688、0.790、0.743、0.683。D-二聚体联合简化Wells评分与简化Wells评分、修订版Geneva评分、4PEPS、D-二聚体联合修订版Geneva评分的AUC差异均有统计学意义(P<0.05),D-二聚体联合修订版Geneva评分与修订版Geneva评分的AUC差异有统计学意义(P<0.05),其它两两对比差异均无统计学意义(P>0.05)。结论D-二聚体联合简化Wells评分诊断价值最高,简化Wells评分优于其它两种评分,修订版Geneva评分、4PEPS评分诊断效果不理想。

血小板体积分布宽度对Wells评分低中危患者发生肺栓塞的预测价值

目的 探讨血小板体积分布宽度(platelet distribution width,PDW)对Wells评分低中危患者发生肺栓塞的预测价值。方法 选择上海健康医学院附属崇明分院2020年1月至2022年1月收治的100例Wells评分为低中危的可疑肺栓塞患者,按照肺栓塞发生情况分为肺栓塞组和非肺栓塞组。比较两组患者的PDW、血小板计数(platelet count,PLT)、血小板平均容积(mean platelet volume,MPV)等血小板相关参数及年龄、性别、体重指数(body mass index,BMI)等临床资料。应用受试者工作特征曲线(receiver operating characteristic,ROC)曲线分析PDW预测Wells评分低中危患者发生肺栓塞的效能及曲线下面积(area under the curve,AUC)。结果 100例患者中42例(42.00%)明确肺栓塞的诊断。肺栓塞组与非肺栓塞组患者的年龄、BMI、性别、Wells评分比较差异无显著性(P>0.05);肺栓塞组患者的PDW、MPV及右心室内径、肺动脉收缩压高于非肺栓塞组,PLT低于非肺栓塞组,差异有显著性(P<0.05)。PDW单独预测Wells评分低中危患者发生肺栓塞的敏感度与特异度分别为83.33%、84.48%,AUC为0.875;PDW联合PLT、MPV预测患者发生肺栓塞的敏感度与特异度分别为92.86%、94.83%,AUC为0.948。结论 Wells评分低中危患者存在较高的肺栓塞风险,PDW单独及联合PLT、MPV均有助于预测该类患者是否会发生肺栓塞。

Flowback and early-time production modeling of unconventional gas wells using an improved semi-analytical method

Multiple fractured horizontal wells (MFHWs) currently are the only possible means of commercial production from the low and ultra-low permeability unconventional gas reservoirs. In early production time, flowback fluid, which constitutes of hydraulic water and gas flow within fractures, is collected and analyzed. Flowback analysis has been shown to be a useful tool to estimate key properties of the hydraulic fracture such as conductivity and pore volume. Until date, most tools of flowback analysis rely on empirical and approximate methods. This study presents an improved Green-function-based semi-analytical solution for performance analysis of horizontal gas wells during flowback and early production periods. The proposed solution is derived based on coupling the solutions of two domains: a rigorously derived Green’s function-based integral solution for single-phase gas flow in matrix, and a finite-difference, multiphase solution for gas–water two-phase flow in the fracture. The validity of proposed semi-analytical solution is verified by finely gridded numerical models built in a commercial simulator for a series of synthetic cases considering a variety of fluid and reservoir property combinations, as well as various different production constraints. Comparisons against available empirical and approximate methods are also provided for these cases.