Characteristics of infant deciduous teeth of the Yangshao culture at the Yuhuazhai site in Xi'an, China

Abstract

In this paper, we observed and measured 168 infant deciduous tooth crowns from the early Yangshao culture (4500 ± BCE) excavated from the Yuhuazhai site in Xi'an, China, in an attempt to reveal the phenotypic characteristics of this population, as well as to complement the morphological characteristics and dimensions of the crowns of prehistoric Chinese deciduous teeth. Additionally, the Yangshao cultural population's formation factors of hereditary traits and their relationship with other groups were investigated using the deciduous teeth. The research methods we used were mainly the buccolingual diameters (BL) and mesiodistal diameters (MD) of the crowns of deciduous teeth with varied dental locations that were measured in addition to the obsevation and statistical analysis of the 11 most representative unmeasured features. Our results indicated the tooth crown shape of the Yuhuazhai infant's deciduous teeth is similar to that of the Northeast Asian population's "Sinodonty," and it also has a small percentage of the Southeast Asian population's "Sundadonty" traits. Additionally, compared to other Chinese groups, this group showed no change in the crown of deciduous teeth in varied dental locations, with the exception of the mandibular second deciduous molar crown, which was somewhat smaller than that of Homo erectus in China. Overall, the morphological traits of infant deciduous teeth in the group are essentially compatible with the genetic characteristics reflected in the skulls of other Yangshao culture populations. Furthermore, the similarity of deciduous tooth size in different Chinese populations may be connected to the continuity of human evolution in China.

Development Adjustment Scheme of a Low-Permeability Reservoir in the SN Oilfield

“…Through the analysis of important production indicators of the whole area and single wells, including pressure, oil production, water cut, water cut rise rate, and remaining recoverable reserves; the development effect is evaluated, the reasons for changes in important production indicators of the whole region and single wells, as well as problems in development, are identified, and corresponding countermeasures are proposed to guide the formulation of subsequent development adjustment plans. Development effect evaluation is a relatively routine work in the development direction of oil and gas fields, and the specific method can be referred to [4][5][6][7][8][9][10][11][12][13][14][15][16]. The water flooding characteristic curve method is used to determine the remaining recoverable reserves in this paper, and commonly used water flooding characteristic curves include type A, B, C, and D [12,13], as shown in Table 1, where α 1 , α 2 , α 3 , α 4 , β 1 , β 2 , β 3 , and β 4 are coefficients; W p , N p , and L p are accumulative water, oil, and liquid production, ×10 4 ton, respectively; R is the recovery; f wl is the limit water cut; and N is the original oil in place, ×10 4 ton.…”

“…The evaluation of the development effect of low-permeability reservoirs can provide guidance and direction for their development adjustment research, and its significance is very obvious. Many researchers conducted in-depth research on it [4][5][6][7][8][9][10][11][12][13][14][15][16], and the research methods mainly include physical experiments and reservoir engineering methods.…”

“…The development effect of switching from seawater flooding to gas flooding had a good development effect, which could effectively improve the oil displacement effect and enhance oil recovery, indicating the next exploration direction for the efficient development of the WS17-2 low-permeability reservoir. Lei et al [5] used the dynamic monitoring data of the research area to conduct dynamic analysis, including production capacity analyses, production decline law research, water injection effectiveness analysis, and production rate analysis. By applying the reservoir engineering method, the water cut increase rate, water flooding index, and water storage rate were evaluated.…”