mlsa-iai-msu-lab/ru_sci_bench_zho_cite_reranking huggingface dataset:
Hydroxycalciopyrochlore, A New Mineral Species from Sichuan, China

Hydroxycalciopyrochlore, ideally (Ca,Na,U,□)_2(Nb,Ti)_2O_6(OH), cubic, is a new mineral species (IMA2011-026) within the pyrochlore supergroup that was found occurring at the Maoniuping mine, Mianning County, Xichang prefecture, Sichuan Province, southwest China. The mineral is found in an alkali feldspar granite rare-earth ore deposit (26–27 Ma). Associated minerals include calcite, barite, celestine, albite, aegirine, aegirine-augite, fluorite, parasite-(Ce), thorite, thorianite, zircon, galena, sphalerite, magnetite, and pyrite. Crystals occur mostly as octahedra, and less often as dodecahedra and tetrahexahedra or combinations thereof. Some occur with an allotriomorphic habit with a thick triangular tabular form. Crystals generally range from 0.1 to 1 mm in size. The mineral is brownishblack, greenish-black and black on fresh sections with a brown streak. The crystal is translucent, and has a greasy lustre on fresh sections. It is metamict without any observed parting or cleavage and with a conchoidal fracture. The Vickers microhardness is 572 kg/mm~2 (5–6 on the Mohs hardness scale). The density measured by hydrostatic weighing is 5.10(3) g/cm~3. The strongest four reflections in the X-ray powder-diffraction pattern [d in A (I) hkl] are: 2.9657 (100) 2 2 2, 1.8142 (34) 0 4 4, 1.5463 (21) 2 2 6, 2.5688 (18) 0 0 4. The unit-cell parameters are a = 10.381(4) A, V = 1118.7(7) A~3, Z = 8. The structure was solved and refined in the space group Fd3m with R = 0.09. The empirical formula is (Ca_(0.74)Na_(0.58)U_(0.40)Ce_(0.05)Fe_(0.02)□_(0.21))_(2.00)(Nb_(1.15)Ti_(0.80)Ta_(0.03)Al_(0.01)Mg_(0.01))_(2.00)O_(6.02) [(OH)_(1.01)F_(0.09)]_(1.10), on the basis of 2 atoms of B pfu; the simplified formula is (Ca,Na,U,□)_2(Nb,Ti)_2O_6(OH). Type material is deposited in the Geological Museum of China, Beijing, People’s Republic of China, catalogue number M11800.
Cenozoic Evolution of Sediments and Climate Change and Response to Tectonic Uplift of the Northeastern Tibetan Plateau

Through a comprehensive study of magnetostratigraphy and sedimentology of several basins in the northeastern Tibetan Plateau, we reveal that the study area mainly experienced six tectonic uplift stages at approximately 52 Ma, 34–30 Ma, 24–20 Ma, 16–12 Ma, 8–6 Ma, and 3.6–2.6 Ma. Comprehensive analyses of pollen assemblages from the Qaidam, Linxia, Xining, and West Jiuquan Basins show that the northeastern Tibetan Plateau has undergone six major changes in vegetation types and climate: 50–40 Ma for the warm-humid forest vegetation, 40–23 Ma for the warm-arid and temperate-arid forest steppe vegetation, 23–18.6 Ma for the warm-humid and temperatehumid forest vegetation, 18.6–8.5 Ma for the warm-humid and cool-humid forest steppe vegetation, 8.6–5 Ma for the temperate sub-humid savanna steppe vegetation, and 5–1.8 Ma for the cold-arid steppe vegetation. Comprehensive comparisons of tectonic uplift events inferred from sedimentary records, climatic changes inferred from pollen, and global climate changes show that in the northeastern Tibetan Plateau the climate in the Paleogene at low altitude was mainly controlled by the global climate change, while that in the Neogene interval with high altitude landscapes of mountains and basins is more controlled by altitude and morphology.
帕金森病患者和健康人群表面肌电特征的比较研究

目前关于帕金森病(PD)患者肌肉运动功能的表面肌电(sEMG)研究在国内尚未见报道,国外的研究亦较少,且结论尚存在一定差异,进一步了解我国PD患者和健康人群肌肉运动时sEMG特征的差异对PD的辅助诊断、肌肉功能状态的客观定量评价、药物和康复疗效的评估具有重要的意义。我们比较了北京地区中老年PD患者和健康对照者在不同负荷水平下肱二头肌分别进行等长和等张收缩时sEMG线性特征(振幅和频率)的差异,旨在为临床评估提供一定的指导。
呼吸机管路储水槽报警器的设计与应用

利用水的浮力及感应线圈感应通电的工作原理设计并制作了呼吸机管路储水槽报警器。在我科监护室呼吸机上使用该储水槽报警器1年的时间里,观察应用后的报警效果。结果表明,该储水槽报警器报警效果稳定,具有安装简单、操作方便、安全高效的特点。
胸腔镜下新生儿先天性膈疝修补术的气道管理

胸腔镜下先天性膈疝修补术对机体的创伤小,利于术后恢复,但CO_2气胸及单肺通气对呼吸及循环功能均可产生影响,因此,单肺通气期间预防低氧血症与高碳酸血症是气道管理的重点,为此有临床尝试在新生儿胸腔镜手术中采用高频振荡呼吸机进行气道管理,结果显示无法彻底避免低氧血症与高碳酸血症,且需要专业的呼吸机操作技能,临床尚未推广。而低死腔或零死腔的导管及流量感应器的临床应用是新生儿机械通气的适宜选择。本课题组拟采用降低机械死腔量的方法,即采用撤掉呼吸回路中的直角接头,并将气管导管剪短至10~11 cm处,换用小0.5号的连接器将导管与Y型接头相连接进行机械通气,评价其气道管理的效果。
Mean Velocity Estimation of Viscous Debris Flows

The mean velocity estimation of debris flows, especially viscous debris flows, is an important part in the debris flow dynamics research and in the design of control structures. In this study, theoretical equations for computing debris flow velocity with the one-phase flow assumption were reviewed and used to analyze field data of viscous debris flows. Results show that the viscous debris flow is difficult to be classified as a Newtonian laminar flow, a Newtonian turbulent flow, a Bingham fluid, or a dilatant fluid in the strict sense. However, we can establish empirical formulas to compute its mean velocity following equations for Newtonian turbulent flows, because most viscous debris flows are turbulent. Factors that potentially influence debris flow velocity were chosen according to two-phase flow theories. Through correlation analysis and data fitting, two empirical formulas were proposed. In the first one, velocity is expressed as a function of clay content, flow depth and channel slope. In the second one, a coefficient representing the grain size nonuniformity is used instead of clay content. Both formulas can give reasonable estimate of the mean velocity of the viscous debris flow.
Cenozoic Fault Distribution Characteristics and Evolution in Qikou Sag of Bohai Basin, China

Qikou sag, located in north-center of Huanghua depression in Bohai Basin, is a Cenozoic sag with rich hydrocarbon. As a microcosm of Bohai Basin, the fault characteristics of Cenozoic structural layers in Qikou sag could indicate and record the evolution of Cenozoic stress field in Bohai Basin. Based on the latest 3-D seismic data, the study takes statistics on the fault system of Cenozoic structural layers and analyzes the fault throws of major large faults along the strikes in different periods in Qikou sag, then the fault distribution regularities and the fault direction characteristics in each structural layer are summarized. The result shows that during Cenozoic, the fault activity strength migrates from southwest to northeast and the strikes of faults changes from northwestward in Sha-3 period to nearly east-westward since Sha-1 period.
Energy Aspects of CO_2 Sorption in the Context of Sequestration in Coal Deposits

This paper summarises the results of experimental testing of carbon dioxide sorption on five coal samples. Sorption tests were done at the temperature 288,298,313 and 323 K, in the pressure range 0-5 MPa. The analysis of sorption isotherms and the effects of temperature on sorption capacity reveal that in the case of samples NR1, Pn, Tu, Be the temperature increase from 298 to 323 K led to 1.3-fold decrease of the sorption value. In the case of coal Th the decrease of sorption capacity was 3-fold. It appears that the analysis of maceral content plays a major role. In the case of coals, porosity is associated with the petrographic composition. The values of the isosteric heat of sorption and the work of expansion and desorption were derived for the investigated sorption systems. Test data reveal that for hard coals the isosteric heat is inversely proportional to the "reserve" of volumetric work-a major parameter triggering the sudden release of gas from the coalbed, thus enabling us to assess the potential risk involved in rapid unsealing of the coalbed.
Morphology and taxonomy of leaf papillae and mammillae in Pottiaceae of China

Both papillae and mammillae are important structural characteristics for Pottiaceae classification, but these characters are diverse and their nomenclature is confused, hindering the classification of Pottiaceae. So, we selected representative species that cover all types of papillae and mammillae of Chinese Pottiaceae and observed and compared differences between them using light and scanning electronic microscopy. We corrected the chaotic descriptions of papillae of representative species, and have provided a uniform set of terms ("simple", "forked", "branched", and "pedicellate") to describe the shapes of papillae. In addition, we described how to quickly and accurately use papillae and mammillae to classify representative species in Chinese Pottiaceae.
Relations between stellar mass and electron temperature-based metallicity for star-forming galaxies in a wide mass range

We select 947 star-forming galaxies from SDSS-DR7 with [O III]λ4363 emission lines detected at a signal-to-noise ratio larger than 5σ. Their electron temperatures and direct oxygen abundances are then determined. We compare the results from different methods. t_2, the electron temperature in the low ionization region, estimated from t_3, that in the high ionization region, is compared using three analysis relations between t_2 - t_3. These show obvious differences, which result in some different ionic oxygen abundances. The results of t_3, t_2, O~(++)/H~+ and O~+/H~+ derived by using methods from IRAF and literature are also compared. The ionic abundances O~(++)/H~+ are higher than O~+/H~+ for most cases. The different oxygen abundances derived from T_e and the strong-line ratios show a clear discrepancy, which is more obvious following increasing stellar mass and strong-line ratio R_(23). The sample of galaxies from SDSS with detected [O III]λ4363 have lower metallicites and higher star formation rates, so they may not be typical representatives of the whole population of galaxies. Adopting data objects from Andrews & Martini, Liang et al. and Lee et al. data, we derive new relations of stellar mass and metallicity for star-forming galaxies in a much wider stellar mass range: from 10~6M_⊙ to 10~(11)M_⊙.
New high spin level scheme of ~(87)Sr

High spin states of the odd-A ~(87)Sr were populated by the fusion-evaporation reaction ~(82)Se(~9Be,4n) ~(87)Sr at a beam energy of 46 MeV. Excited levels of ~(87)Sr have been extended up to an excitation energy of 7.4 MeV at spin 31/2h. The coupling of a g_(9/2) neutron hole to the yrast states of the ~(88)Sr core can account for the low-lying states in ~(87)Sr. The structure of the higher spin states is discussed by analogy with those of the neighboring odd-A N=49 isotones and possible configurations are proposed.
Exact treatment of pairing correlations in Yb isotopes with covariant density functional theory

The effects of pairing correlation in Yb isotopes are investigated by covariant density functional theory with pairing correlations and blocking effects treated exactly by a shell model like approach (SLAP). Experimental one- and two-neutron separation energies are reproduced quite well. The traditional BCS calculations always give larger pairing energies than those given by SLAP calculations, particularly for the nuclei near the proton and neutron drip lines. This may be caused because many of the single particle orbits above the Fermi surface are involved in the BCS calculations, but many of them are excluded in the SLAP calculations.
香椿的化学成分研究进展

香椿是我国特有的珍贵速生药材树种,通过SciFinder等工具或数据库检索、查阅近期在国内外期刊上发表的相关论文,系统地综述了香椿化学成分的研究情况,为其进一步的研究与开发提供参考。到目前为止,共计报道了从香椿中分离得到的100个化合物,包括黄酮类19个、萜类44个、苯丙素类7个、酚类14个和16个其它类别化合物。香椿的化学成分研究以黄酮类和三萜类化合物为主导。
牙隐裂磨牙治疗的临床疗效观察

牙隐裂是指未经治疗的牙齿表面由于某些因素的长期作用,而出现的临床不易发现的细微裂纹,是牙裂综合征(cracked tooth syndrome,CTS)中活髓牙发生牙裂的特殊病例,多见于中老年患者。易导致漏诊、误诊,最终引起牙髓病变,甚至折裂。笔者在牙科手术显微镜辅助下,对58颗活髓隐裂患牙进行充填治疗,获得较好疗效,现报道如下。
Contrasting Response Patterns of Rice Phyllosphere Bacterial Taxa to Elevated CO_2

A vast number of microorganisms colonize the leaf surface of terrestrial plants, known as the phyllosphere, and these microorganisms are thought to be of critical importance in plant growth and health. However, the taxonomic identities and ecological functions of the microorganisms inhabiting the rice phyllosphere remain poorly understood. Using a massive, parallel pyrosequencing technique, we identified the phyllosphere bacterial taxa of four different rice varieties and investigated the microbial response to elevated CO_2 (eCO_2) in a rice field of a free-air CO_2 enrichment (FACE) facility located in Jiangsu Province, China. The results showed that the dominant phylotype, the Enterobacteriaceae family of Gammaproteobacteria, accounted for 70.6%–93.8% of the total bacterial communities in the rice phyllosphere. The dominant phylotype was stimulated by eCO_2, with its relative abundance increasing from 70.6%–75.2% at ambient CO_2 (aCO_2) to 86.5%–93.8% at eCO_2 in the phyllosphere of rice varieties IIYou084 (TY-084), YangLiangYou6 (YLY-6), and ZhenXian96 (ZX-96). The rare phylotypes, including the bacterial taxa of Sphingobacteriaceae, Xanthomonadaceae, Oxalobacteraceae, Clostridiaceae, and Pseudomonadaceae, were suppressed and their relative abundance decreased from 13.4%–23.0% at aCO_2 to 1.47%–6.11% at eCO_2. Furthermore, the bacterial diversity indices decreased at eCO_2 in the phyllosphere of the rice varieties TY-084, YLY-6, and ZX-96. In contrast, an opposite response pattern was observed for the rice variety of YangDao8 (YD-8). In the phyllosphere of this variety, the relative abundance of the dominant phylotype, Enterobacteriaceae, decreased from 94.1% at aCO_2 to 81.4% at eCO_2, while that of the rare phylotypes increased from 3.37% to 6.59%. In addition, eCO_2 appeared to stimulate bacterial diversity in the rice variety YD-8. Our results suggest that the phyllosphere microbial response to eCO_2 might be relative abundance-dependent in paddy fields.
Effect of Soil Water Repellency on Energy Partitioning Between Soil and Atmosphere: A Conceptual Approach

Water repellency (WR) is a phenomenon known from many soils around the world and can occur in arid as well as in humid climates; few studies, however, have examined the effect of soil WR on the soil-plant-atmosphere energy balance. The aim of our study was to estimate the effects of soil WR on the calculated soil-atmosphere energy balance, using a solely model-based approach. We made out evapotranspiration to have the largest influence on the energy balance; therefore the effect of WR on actual evapotranspiration was assessed. To achieve this we used climate data and measured soil hydraulic properties of a potentially water-repellent sandy soil from a site near Berlin, Germany. A numerical 1D soil water balance model in which WR was incorporated in a straightforward way was applied, using the effective cross section concept. Simulations were carried out with vegetated soil and bare soil. The simulation results showed a reduction in evapotranspiration of 30–300 mm year~(?1) (9%–76%) at different degrees of WR compared to completely wettable soil, depending on the severity degree of soil WR. The energy that is not being transported away by water vapor (i.e., due to reduced evapotranspiration) had to be transformed into other parts of the energy balance and thus would influence the local climate.
Effects of Tillage and Crop Residue Management on Maize Yields and Net Returns in the Central Mexican Highlands Under Drought Conditions

In the subtropical highlands of Central Mexico, where the main crop is maize (Zea mays), the conventional practice (CP) involves tillage, monoculture and residue removal, leading to soil degradation and unsustainable use of natural resources and agricultural inputs. Conservation agriculture (CA) has been proposed as a viable alternative in the region, based on reduction in tillage, retention of adequate levels of crop residues and soil surface cover and use of crop rotation. This study began in 2009 when the highlands of Central Mexico suffered from a prolonged drought during vegetative maize growth in July–August, providing an opportunity for the on-farm comparison of CA with CP under severe drought conditions which 21 climate change models projected to become more frequent. Under dry conditions, CA resulted in higher yields and net returns per hectare as early as the first and second years after adoption by farmers. As an average of 27 plots under farmers’ management in 2009, the maize yields were 26% higher under CA (6.3 t ha~(?1)) than under CP (5.0 t ha~(?1)). 2010 was close to a normal year in terms of rainfall so yields were higher than in 2009 for both practices; in addition, the yield difference between the practices was reduced to 19% (6.8 t ha~(?1) for CA vs. 5.7 t ha~(?1) for CP). When all the 2009 and 2010 observations were analyzed in a modified stability analysis, CA had an overall positive effect of 3 838 Mexican Pesos ha~(?1) (320 $US ha~(?1)) on net return and 1.3 t ha~(?1) on yield. After only one to two years of adoption by farmers on their fields, CA had higher yields and net returns under dry conditions that were even drier than those predicted by the analyzed 21 climate change models under a climate change scenario, emission scenario A2.
Nitrous Oxide and Methane Fluxes During the Maize Season Under Optimized Management in Intensive Farming Systems of the North China Plain

Addressing concerns about mitigating greenhouse gas (GHG) emissions while maintaining high grain yield requires improved management practices that achieve sustainable intensification of cereal production systems. In the North China Plain, a field experiment was conducted to measure nitrous oxide (N_2O) and methane (CH_4) fluxes during the maize (Zea mays L.) season under various agricultural management regimes including conventional treatment (CONT) with high N fertilizer application at a rate of 300 kg N ha~(?1) and overuse of groundwater by flood irrigation, optimal fertilization 1 treatment (OPT1T), optimal fertilization 2 treatment (OPT2T), and controlled-release urea treatment (CRUT) with reduced N fertilizer application and irrigation, and a control (CK) with no N fertilizer. In contrast to CONT, balanced N fertilization treatments (OPT1T, OPT2T, and CRUT) and CK demonstrated a significant drop in cumulative N_2O emission (1.70 v.s. 0.43–1.07 kg N ha~(?1)), indicating that balanced N fertilization substantially reduced N_2O emission. The values of the N_2O emission factor were 0.42%, 0.29%, 0.32%, and 0.27% for CONT, OPT1T, OPT2T, and CRUT, respectively. Global warming potentials, which were predominantly determined by N_2O emission, were estimated to be 188 kg CO_2-eq ha~(?1) for CK and 419–765 kg CO_2-eq ha~(?1) for the N fertilization treatments. Global warming potential intensity calculated by considering maize yield was significantly lower for OPT1T, OPT2T, CRUT, and CK than for CONT. Therefore, OPT1T, OPT2T, and CRUT were recommended as promising management practices for sustaining maize yield and reducing GHG emissions in the North China Plain.
Colony Characteristics and Genetic Diversity of Cytospora chrysosperma Strains from Ten Provinces in China

Totally 30 strains of Cytospora chrysosperma causing poplar canker,derived from ten provinces in China were classified into two clusters based on the cluster analysis of colony characteristics. The first cluster was separated into the geographic groups of Xinjiang,Beijing-Northeast and Shandong and the second cluster was separated into the geographic groups of Inner Mongolia and Sichuan-Gansu-Shaanxi-Qinghai. In ferm of RAPD makers,the 30 strains were also separated into two clusters by the cluster analysis. The first cluster was classified into the geographic groups of Beijing, Xinjiang,Liaoning,Gansu-Qinghai and Shandong-Heilongjian-Jilin-Shaanxi. The second cluster was separated into the geographic groups of Inner Mongolia and Sichuan. The results showed a clear relationship between the geographical origin and the colony characteristics or genetic diversity of the pathogenic fungus.
解郁起阳汤联合小剂量西地那非治疗心理性勃起功能障碍的临床观察

目的:观察解郁起阳汤联合小剂量西地那非对心理性勃起功能障碍的临床疗效。方法:将98例肝气郁结、肾阳亏虚型心理性勃起功能障碍患者随机分入治疗组和对照组。对照组以小剂量西地那非治疗;治疗组在对照组基础上加用解郁起阳汤治疗。共治疗6周。治疗前后采用国际勃起功能指数问卷(international index of erectile function,ⅡEF-5)和中医证候积分对比评价疗效。结果:两组治疗后的ⅡEF-5评分均较治疗前显著提高(治疗组P < 0.01,对照组P < 0.05)。治疗后治疗组ⅡEF-5评分和临床症状改善优于对照组(P < 0.05)。结论:解郁起阳汤联合小剂量西地那非能改善心理性勃起功能障碍患者的阴茎勃起功能,消除心理障碍,并起到调整全身整体状态的作用。
竹节参及其混淆品景天三七的比较鉴别

目的:建立鉴别竹节参及其混淆品景天三七的方法。方法:采用性状鉴别、显微鉴别(组织横切片、药材粉末)对竹节参及景天三七的特征进行比较。结果:竹节参与景天三七的性状、显微特征均具有一定差异。尤其可以通过显微特征中,草酸钙簇晶、草酸钙砂晶、分泌道(树脂道碎片)的有无,导管、淀粉粒的类型等作为鉴别要点进行区分。结论:本研究结果可作为竹节参与景天三七药材及粉末的鉴别方法。
个案管理模式的国内外研究现状

对个案管理模式的概念、起源与发展以及国内外的应用现状进行了综述,个案管理目前应用较多的领域包括糖尿病、心力衰竭、乳腺癌、哮喘、HIV、慢性阻塞性肺疾病及腹膜透析等。提出我国进行的系统化、程序化的个案管理研究较少,所涉及专科领域较窄,专科护士培养还处于探索阶段。因此,有必要进一步扩展研究领域,深入探索适合我国国情的个案管理模式。
晚娩肩助产预防新生儿产伤效果观察

目的探讨晚娩肩助产对足月单胎阴道分娩的新生儿产伤的预防效果。方法采用回顾性观察研究,比较1 120例实施晚娩肩助产(观察组)与973例未采用晚娩肩方法助产(对照组)产妇的分娩结果,分析两组新生儿体质量、窒息、锁骨骨折、臂丛神经损伤发生率的差异。结果两组新生儿体质量、窒息发生率比较,差异无统计学意义(均P>0.05);观察组新生儿锁骨骨折、臂丛神经损伤发生率显著低于对照组(均P<0.05)。结论晚娩肩助产有利于降低新生儿产伤发生率,提高产妇分娩质量。
Measurement Method of Compressibility and Thermal Expansion Coefficients for Density Standard Liquid at 2329 kg/m~3 based on Hydrostatic Suspension Principle

The accurate measurement on the compressibility and thermal expansion coefficients of density standard liquid at 2329kg/m~3 (DSL-2329) plays an important role in the quality control for silicon single crystal manufacturing. A new method is developed based on hydrostatic suspension principle in order to determine the two coefficients with high measurement accuracy. Two silicon single crystal samples with known density are immersed into a sealed vessel full of DSL-2329. The density of liquid is adjusted with varying liquid temperature and static pressure, so that the hydrostatic suspension of two silicon single crystal samples is achieved. The compression and thermal expansion coefficients are then calculated by using the data of temperature and static pressure at the suspension state. One silicon single crystal sample can be suspended at different state, as long as the liquid temperature and static pressure function linearly according to a certain mathematical relationship. A hydrostatic suspension experimental system is devised with the maximal temperature control error ±50 mK; Silicon single crystal samples can be suspended by adapting the pressure following the PID method. By using the method based on hydrostatic suspension principle, the two key coefficients can be measured at the same time, and measurement precision can be improved due to avoiding the influence of liquid surface tension. This method was further validated experimentally, where the mixture of 1, 2, 3-tribromopropane and 1,2-dibromoethane is used as DSL-2329. The compressibility and thermal expansion coefficients were measured, as 8.5′10~(-4) K~(-1) and 5.4′10~(-10) Pa~(-1), respectively.
Strength-Toughening Model of Eutectic Ceramic Composite with Inherent Defects

Strengthening and toughening mechanisms in composite ceramics is complex. A change in a single parameter induces multiple property variations. The multiple changes in properties are often incompletely represented in theoretical models. This incompleteness in the parameter chosen fails to explain the mechanism of failure in composite ceramics. The exponential toughness function is used to represent the pull-out toughening mechanism, which dominates the crack growth resistance curve(R-curve). The strengthening-toughening model is established based on the Mori-Tanaka method(M-T method). The influence of inherent defects on toughness function and strength is analyzed by using this model. The theoretical result is compared with the experiment data. This model exactly reflects the change in strength. The theoretical result indicates that defects change the toughness function. Moreover, micro-cracks increase toughness size ac, and the strength of crack instable extensions acutely decreases as defect content increases. This presented model establishes the relationship among the important mechanical parameters of defect, strength, elastic modulus, and the R-curve.