Screening Effect of the Diffusive Boundary Layer in Sediments of Lake Aha in the Suburbs of Guiyang City, Guizhou Province

The redox cycle of iron and manganese is a major geochemical process at the boundary layers of lake sediments. Lake Aha, which lies in the suburbs of Guiyang City,Guizhou Province, China, is a medium-sized artificial reservoir with seasonally anoxic hypolimnion. Long-term sedimentary accumulation of iron and manganese resulted in their enrichment in the upper sediments. In the anoxic season, Fe2+ and Mn2+, formed by biological oxidation, would diffuse up to overlying waters from sedlments. However, the concentration of Fe2+ increased later and decreased earlier than that of Mn2+. Generally, sulfate reduction occurred at 6 cm below the sediment-water interface. Whereas, in the anoxic season, the reduction reached upper sediments, inhibiting the release of Fe2+. The Fe concentration of anoxic water is quickly decreased from high to low as a result of reduction Of the sulphur system.

Assessing the Effectiveness of a Cervical Cancer Screening Program in a Hospital-based Study

This study compared HPV testing and liquid-based cytology （LCT） as performance indicators for cervical cancer screening in a hospital-based study. A total of 61,193 outpatients were screened initially by LCT. Samples with screening results showing atypical squamous cells of undetermined significance （ASC-US） or worse were referred for colposcopy, and some samples were tested for high-risk HPV types with the Hybrid Capture II system （HC II）. Data on LCT （n=61,193） and HC II （n=1056） results were analysed. Overall test positivity for LCT was 2.53% using an ASC-US threshold, 3.11% using a low-grade squamous intraepithelial lesion （LSIL） threshold, and 0.67% using a high-grade squamous intraepithelial lesion （HSIL） threshold. A total of 1839 women （84% of the 3893 patients with abnormal cytology） underwent colposcopy-directed biopsy. HPV was positive in 80.3% of women with cervical intraepithelial neoplasia 1 （CIN1）, 88.3% of those with CIN2, 79.2% of women with CIN3 and 50% （2 of 4） of women with invasive cancer. There was a significant increase in the detection of CIN2 or worse with adjunct HPV testing of women with ASC-US and LSIL However, there were detection of CIN2＋ cases no differences in the with adjunct HPV testing of women with HSlI.. The results indicate that HPV testing for HSlL triage should not be recommended in cervical cancer screening.

Screening influence on the Stark effect of impurity states in strained wurtzite GaN/Al_xGa_(1-x)N heterojunctions under pressure

The screening effect of the random-phase-approximation on the states of shallow donor impurities in free strained wurtzite GaN/AlxGa1-xN heterojunctions under hydrostatic pressure and an external electric field is investigated by using a variational method and a simplified coherent potential approximation. The variations of Stark energy shift with electric field, impurity position, A1 component and areal electron density are discussed. Our results show that the screening dramatically reduces both the blue and red shifts as well as the binding energies of impurity states. For a given impurity position, the change in binding energy is more sensitive to the increase in hydrostatic pressure in the presence of the screening effect than that in the absence of the screening effect. The weakening of the blue and red shifts, induced by the screening effect, strengthens gradually with the increase of electric field. Furthermore, the screening effect weakens the mixture crystal effect, thereby influencing the Stark effect. The screening effect strengthens the influence of energy band bending on binding energy due to the areal electron density.

The effect of dynamical screening on helium(e,2e) fully differential cross-sections

This paper presents the fully differential cross sections （FDCS） for 102eV electron impact single ionization of helium for both the coplanar and perpendicular plane asymmetric geometries within the framework of dynamically screened three-Coulomb-wave theory. Comparisons are made with the experimental data and those of the three-Coulomb wave function model and second-order distorted-wave Born method. The angular distribution and relative heights of the present FDCS is found to be in very good agreement with the experimental data in the perpendicular plane geometry. It is shown that dynamical screening effects are significant in this geometry. Three-body coupling is expected to be weak in the coplanar geometry, although the precise absolute value of the cross section is still sensitive to the interaction details.

Higher Order Multipole Potentials and Electrostatic Screening Effects on Cohesive Energy and Bulk Modulus of Metallic Nanoparticles

Higher order rnultipole potentials and electrostatic screening effects are introduced to incorporate the dan gling bonds on the surface of a metallic nanopaticle and to modify the coulornb like potential energy terms, respectively. The total interaction energy function for any rnetallic nanoparticle is represented in terms of two- and three-body potentials. The two-body part is described by dipole-dipole interaction potential, and in the three-body part, triple-dipole （DDD） and dipole-dipole-quadrupole （DDQ） terrns are included. The size-dependent cohesive energy and bulk modulus are observed to decrease with decreasing sizes, a result which is in good agreement with the experimental values of Mo and W nanoparticles.

Plasma-screening effects on positronium formation

Plasma-screening effects on positronium （Ps） formation for positron-hydrogen collisions in a Debye plasma environ- ment is further investigated using the screening approximation model with the inclusion of the modified structure of Ps. More accurate Ps formation cross sections （n = 1,2） are obtained for various Debye lengths from the Ps formation thresh- olds to 50 eV. The influence of considering modified bound-state wave functions and eigenenergies for the Ps is found to result in the reduction of the Ps formation cross sections at low energies, whereas it cannot counteract the enhancement of the Ps formation by the Debye screening.

Cancer screening:Between appropriateness and effectiveness

Two similar words, effectiveness and efficacy, have comparable insight and nearly describe analogous mea-ning for a screening test, yet clear understanding and perception of their diverse meanings will help clarify the basis of the differing conclusions about whether screening tests for different cancers reduce morbidity and mortality. Screening test may not be effective even when it sounds to be efficacious, on the other hand it should be efficacious when the test is effective.

Mass scale screening of common arboviral infections by an affordable,cost effective RT-PCR method

Objective:To develop a rapid,cost effective RT-PCR method for the mass scale diagnosis of such diseases at the vireraia stage to find out the actual disease burden in that area.Methods:For this purpose,cases with the history of only short febrile illness were considered.Thus 157 samples with the history of dengue/chikungunya like illness and only 58 samples with a history of acute encephalitis syndrome(AES)were selected.Results:Out of 157 samples,42 and 74 were detected as dengue and chikungunya,respectively and out of 58 AES cases only 23 could be detected as Japanese encephalitis by this RT-PCR method.Conclusions:This cost effective RT-PCR method can detect the total positive cases that remain undetected by EL1SA method.Moreover,this method is capable to detect the viral RNA from patients'sera even after the appearance of IgM antibody at one fifth costs as compared with the other commercially available kits.

Temperature effect on dissipative holographic screening-photovoltaic solitons in a biased dissipative system

In a biased dissipative photovoltaic-photorefractive system, this paper investigates the temperature effect on the evolution and the self-deflection of the dissipative holographic screening-photovoltaic （DHSP） solitons. The results reveal that, the evolution and the self-deflection of the bright and dark DHSP solitons are influenced by the system temperature. At a given temperature, for a stable DHSP soliton originally formed in the dissipative system, it attempts to evolve into another DHSP soliton when the temperature change is appropriately small, whereas it will become unstable or break down if the temperature departure is large enough. Moreover, the self-deflection degree of the solitary beam centre increases as temperature rises in some range, while it is decided by the system parameters and is slight under small-signal condition. The system temperature can be adjusted to change the formation and the self-deflection of the solitary beam in order to gain certain optical ends. In a word, the system temperature plays a role for the DHSP solitons in the dissipative system.

Binding Energies of Screened Excitons in a Strained(111)-Oriented Zinc-Blende GaN/AlGaN Quantum Well Under Hydrostatic Pressure

We investigate the binding energies of excitons in a strained （111）-oriented zinc-blende GaN/Al0.3 Ga0.7 N quantum well screened by the electron-hole （e-h） gas under hydrostatic pressure by combining a variational method and a selfconsistent procedure. A built-in electric field produced by the strain-induced piezoelectric polarization is considered in our calculations. The result indicates that the binding energies of excitons increase nearly linearly with pressure,even though the modification of strain with hydrostatic pressure is considered, and the influence of pressure is more apparent under higher e-h densities. It is also found that as the density of an e-h gas increases,the binding energies first increase slowly to a maximum and then decrease rapidly when the e-h density is larger than about 1 ×10^11 cm^-2. The excitonic binding energies increase obviously as the barrier thickness decreases due to the decrease of the built-in electric field.

孤独症谱系障碍早期筛查量表在儿童保健门诊的应用效果

目的探讨适合基层的孤独症谱系障碍(autism spectrum disorder,ASD)早期筛查方法,提高基层医生对ASD的识别能力。方法采用回顾性研究方法,选取2020年10月至2021年7月于成都市金牛区妇幼保健院进行定期健康体检的18~30月龄儿童为研究对象,使用婴幼儿孤独症筛查-23(checklist for autism in toddlers-23,Chat-23)量表结合ASD预警征询问和现场观察的初级筛查方法,共筛查2437名。对筛查阳性并确诊发育异常的31名儿童使用象征性游戏测试(symbolic play test,SPT)和婴幼儿语言发育筛查量表进行评估,探讨适合基层医院开展的ASD早期筛查方式。统计学方法采用单因素方差分析、χ^(2)检验、Fisher确切概率法、受试者工作特征(receiver operating characteristic,ROC)曲线分析。结果男童和女童Chat-23量表A部分阳性率[2.11%(27/1281)与0.95%(11/1156),χ^(2)=5.292,P=0.021]、B部分阳性率[2.03%(26/1281)与0.61%(7/1156),χ^(2)=9.226,P=0.002]比较,男童明显高于女童,而不同月龄儿童Chat-23量表A部分、B部分阳性率比较差异均无统计学意义(P值均>0.05);不同性别、儿童ASD预警征、现场观察阳性率比较,差异均无统计学意义(P值均>0.05)。ROC曲线分析结果显示,Chat-23量表筛查ASD的曲线下面积(area under the curve,AUC)为0.946,敏感度为90.00%,特异度为99.18%(P<0.05)。ASD患儿SPT量表、婴幼儿语言发育筛查量表B部分得分均明显低于全面发育迟缓和语言发育迟缓患儿,差异均有统计学意义(P值均<0.05);3组患儿在婴幼儿语言发育筛查量表A部分和C部分得分方面,差异均无统计学意义(P值均>0.05)。结论Chat-23量表可用于基层医院早期筛查ASD,结合SPT量表和婴幼儿语言发育筛查量表可以提高基层医生对ASD的鉴别诊断能力。

Screening of plane S waves by an array of rigid piles in poroelastic soil

An array of rigid piles used as a screening barrier for plane shear (S) waves is investigated in a homogeneous unbounded space. The dynamic poroelastic theory of Biot is employed, under the assumption of an incompressible solid grain. Using Fourier-Bessel series, the problem of multiple scattering is solved by imposing continuity conditions and equilibrium conditions at the soil-pile interfaces with the translational addition theorem. A parametric analysis is conducted to investigate the influence of the permeability of poroelastic soil, separation between piles, number of piles and frequency of incident waves on screening effectiveness of the barrier, and the results are compared with those in an elastic soil medium. Computed results show that the intrinsic permeability of the soil medium displays an apparent effect on the screening of plane S waves.

Hypoglycaemic effect of Berberis vulgaris L.in normal and streptozotocin-induced diabetic rats

Objective:To achieve a primary pharmacological screening contained in the aqueous extract of Berberis vulgaris(B.vulgaris) and to examine the hypoglycaemic effect and biochemical parameters of aqueous and saponins extract on groups of rats rendered diabetic by injection of streptozotocin.Methods:The phytochemicol tests to detect the presence of different compounds were based on the visual observation of color change or formation of precipitate after the addition of specific reagents.Diabetes was induced in rats by intraperitoneal(i.p.) injection of streptozotocin(STZ) at a dose of 65 mg/kg bw.The fasting blood glucose levels were estimated by glucose oxidase-peroxidase reactive strips(Dextrostix,Bayer Diagnostics).Blood samples were taken by cutting the tip of the tail.Serum cholesterol and serum triglycerides were estimated by enzymatic DHBS colorimetric method.Results:Administration of 62.5 and 2S.0 mg/kg of saponins and aqueous extract respectively in normal rats group shows a significant hypoglycemic activity(32.33%and 40.17%respectively) during the first week.However,diabetic group treated with saponin extract produced a maximum fall of 73.1%and 76.03%at day 1 and day 21 compared to the diabetics control.Also,blood glucose levels of the diabetic rats treated with aqueous extract showed decrease of 78.79%on the first day and the effect remains roughly constant during 3 week. Both extracts also declined significantly biochemical parameters(20.77%-49.00%).The control in the loss of body weight was observed in treated diabetic rats as compared to diabetic controls. Conclusions:These results demonstrated significant antidiabetic effects and showed that serum cholesterol and serum triglycerides levels were decreased,significantly,consequently this plant might be of value in diabetes treatment.

Stability of the positively charged manganese centre in GaAs heterostructures examined theoretically by the effective mass approximation calculation near the Γ critical point

This paper describes an n-i-p-i-n model heterostructure with a manganese （Mn）-doped p-type base region to check the stability of a positively charged manganese A＋Mn centre with two holes weakly bound by a negatively charged 3dS（Mn） core of a local spin S = 5/2 in the framework of the effective mass approximation near the F critical point （k -0）. By including the carrier screening effect, the ground state energy and the binding energy of the second hole in the positively charged centre A＋Mn are calculated within a hole concentration range from 1 ×10^16 cm-3 to 1 × 10^17 cm^-3, which is achievable by biasing the structure under photo-excitation. For comparison, the ground-state energy of a single hole in the neutral AMn centre is calculated in the same concentration range. It turns out that the binding energy of the second hole in the A＋Mn centre varies from 9.27 meV to 4.57 meV. We propose that the presence of the A＋Mn centre can be examined by measuring the photoluminescence from recombination of electrons in the conduction band with the bound holes in the A＋Mn centre since a high frequency dielectric constant of ε∞ = 10.66 can be safely adopted in this case. The novel feature of the ability to tune the impurity level of the A＋Mn centre makes it attractive for optically and electrically manipulating local magnetic spins in semiconductors.

Nonlinear magneto-mechanical-thermo coupling characteristic analysis for transport behaviors of carriers in composite multiferroic piezoelectric semiconductor nanoplates with surface effect

In this paper,to better reveal the surface effect and the screening effect as well as the nonlinear multi-field coupling characteristic of the multifunctional piezoelectric semiconductor(PS)nanodevice,and to further improve its working performance,a magneto-mechanical-thermo coupling theoretical model is theoretically established for the extensional analysis of a three-layered magneto-electro-semiconductor coupling laminated nanoplate with the surface effect.Next,by using the current theoretical model,some numerical analyses and discussion about the surface effect,the corresponding critical thickness of the nanoplate,and the distributions of the physical fields(including the electron concentration perturbation,the electric potential,the electric field,the average electric displacement,the effective polarization charge density,and the total charge density)under different initial state electron concentrations,as well as their active manipulation via some external magnetic field,pre-stress,and temperature stimuli,are performed.Utilizing the nonlinear multi-field coupling effect induced by inevitable external stimuli in the device operating environment,this paper not only provides theoretical support for understanding the size-dependent tuning/controlling of carrier transport as well as its screening effect,but also assists the design of a series of multiferroic PS nanodevices.

Screening of a Test Charge in Plasma

Nonlinear screening of a test charge in plasma by electrons trapped or untrapped is studied. The obtained results are in rigorous estimations mathematically in comparison with the corresponding Debye screening forms.Meanwhile their validity is physically discussed and some confusions in literature are clarified.

a-Decay half-life screened by electrons

In this paper,by considering the electrons in different external environments,including neutral atoms,a metal,and an extremely strong magnetic-field environment,the screened a-decay half-lives of the a emitters with proton number Z = 52–105 are systematically calculated.In the external environment,the decay energy and the interaction potential between a particle and daughter nucleus are both changed due to the electron screening effect and their variations are both very important for the electron screening effect.Besides,the electron screening effect is found to be closely related to the decay energy and its proton number.

Proof of Effectiveness of Generalized Modus Ponents Method R_w

This paper gives a proof of generalized modus ponents (GMP) method R W proposed in , and shows this method has the ability to elimitate the symmetrical and screened effects existing in method R s.

Primary Research on Screening of Herbicides in Summer Sowing Broomcorn Millet Field

[ Objective] The paper was to select the suitable herbicides for summer sowing breomcom millet and reduce labor costs. [ Method ] More than 20 kinds of herbicides commonly used in fields had been preliminarily screened, and six kinds of herbicides were selected for further field herbicidal effect experiment. [ Re- suit] The herbicidal effects of 2,4-D butylate, MCPA-Na, tribenuren, 2,4-D isooctyl ester and monosulfuren plus prepasine against Pharbitis nil （ lAan. ） Choisy, Amaranth mangostanus L. and Portulaca oleracea L. were greater than 70%, and the weed control effect on fresh weight by leaf and stem spray of tribenu- ran and MCPA-Na were greater than 96% after herbicide application for 20 d. [ Concluslon] The study provides the guidance for production of breomcom millet.