Surface or submerged horizontal or vertical plate can be considered as a new concept breakwater. This paper investigates the wave-plate interaction of this type of breakwater by use of the boundary element method. The...Surface or submerged horizontal or vertical plate can be considered as a new concept breakwater. This paper investigates the wave-plate interaction of this type of breakwater by use of the boundary element method. The relationships of wave transmitted and reflected among plate thickness, submergence and length are carefully studied by numerical simulation. It is shown that： （1） The transmitted coefficients of submerged horizontal plate or vertical plate will become larger with the increase of plate thickness and reduce rapidly with the decrease of plate submergence. （2） Both surface horizontal and vertical plate are efficient for intermediate and short wave elimination, but vertical plate is more effective. （3） Submerged horizontal plate can act more effectively than submerged vertical plate does. With all wave frequencies, the vertical plate almost has no wave elimination effect.展开更多
A study has been made on the reflected and transmitted powers generated when an arbitrarily polarized plane wave impinges at a planar interface separating an isotropic achiral medium(IAM) and an isotropic chiral mediu...A study has been made on the reflected and transmitted powers generated when an arbitrarily polarized plane wave impinges at a planar interface separating an isotropic achiral medium(IAM) and an isotropic chiral medium(ICM). It follows that the theoretical formulas are derived for the normalized reflection and transmission powers from an IAM–ICM interface for an arbitrary polarized incident wave, and those at an ICM–IAM interface for right-hand circularly polarized(RCP) or left-hand circularly polarized(LCP) incident wave are also obtained. The behavior of the reflected and transmitted waves in different cases is studied, and the dependence of the reflection/transmission of the incident wave on the incident angle and the parameters of the media is investigated in detail. Our numerical results show that high transmission is exhibited under the impedance matching condition and the incident wave can be split into two waves of the same circular polarization state in the case of the ICM–IAM interface, which indicates that circular polarizing beam splitter is achieved.展开更多
Femtosecond pump-terahertz probe studies of carrier dynamics in semi-insulating CaAs have been investigated in detail for various pump powers. It is observed that, at high pump powers, the reflection peaks flip to the...Femtosecond pump-terahertz probe studies of carrier dynamics in semi-insulating CaAs have been investigated in detail for various pump powers. It is observed that, at high pump powers, the reflection peaks flip to the opposite polarity and dramatically enhance as the pump arrival time approaches the reflected wave of the terahertz pulse. The abnormal polarity-flip and enhancement can be interpreted by the pump-induced enhancement in the photoconductivity of GaAs and half-wave loss. Moreover, the carrier relaxation processes and surface states filling in GaAs are also studied in these measurements.展开更多
This study primarily aimed to investigate the prevalence of human papillomavirus(HPV)and other common pathogens of sexually transmitted infections(STIs)in spermatozoa of infertile men and their effects on semen parame...This study primarily aimed to investigate the prevalence of human papillomavirus(HPV)and other common pathogens of sexually transmitted infections(STIs)in spermatozoa of infertile men and their effects on semen parameters.These pathogens included Ureaplasma urealyticum,Ureaplasma parvum,Chlamydia trachomatis,Mycoplasma genitalium,herpes simplex virus 2,Neisseria gonorrhoeae,Enterococcus faecalis,Streptococcus agalactiae,Pseudomonas aeruginosa,and Staphylococcus aureus.A total of 1951 men of infertile couples were recruited between 23 March 2023,and 17 May 2023,at the Department of Reproductive Medicine of The First People’s Hospital of Yunnan Province(Kunming,China).Multiplex polymerase chain reaction and capillary electrophoresis were used for HPV genotyping.Polymerase chain reaction and electrophoresis were also used to detect the presence of other STIs.The overall prevalence of HPV infection was 12.4%.The top five prevalent HPV subtypes were types 56,52,43,16,and 53 among those tested positive for HPV.Other common infections with high prevalence rates were Ureaplasma urealyticum(28.3%),Ureaplasma parvum(20.4%),and Enterococcus faecalis(9.5%).The prevalence rates of HPV coinfection with Ureaplasma urealyticum,Ureaplasma parvum,Chlamydia trachomatis,Mycoplasma genitalium,herpes simplex virus 2,Neisseria gonorrhoeae,Enterococcus faecalis,Streptococcus agalactiae,and Staphylococcus aureus were 24.8%,25.4%,10.6%,6.4%,2.4%,7.9%,5.9%,0.9%,and 1.3%,respectively.The semen volume and total sperm count were greatly decreased by HPV infection alone.Coinfection with HPV and Ureaplasma urealyticum significantly reduced sperm motility and viability.Our study shows that coinfection with STIs is highly prevalent in the semen of infertile men and that coinfection with pathogens can seriously affect semen parameters,emphasizing the necessity of semen screening for STIs.展开更多
Sexually transmitted infections (STIs) represent a public health problem due to their high prevalence worldwide and the emergence of multidrug resistance of responsible microorganisms. Medical laboratory diagnosis of ...Sexually transmitted infections (STIs) represent a public health problem due to their high prevalence worldwide and the emergence of multidrug resistance of responsible microorganisms. Medical laboratory diagnosis of sexually transmitted genital infections by traditional methods as culture remains extremely delicate, difficult or impossible (to find extremely fragile organisms that can be cultured). Thus, molecular techniques constitute an alternative to improve accurate diagnostic, personalized patient treatment, and public health. A total of 83 clinical samples including urethral discharge and urine samples from individual patients with symptoms of urethritis received were analyzed using traditional methods and a commercial real-time PCR (qPCR) method. Out of 83 urethritis patients, n = 55 (66.26%) were positive for at least one of the STI pathogens detected by qPCR. qPCR assay was more sensitive (50/83, positive cases) compared to culture (15/83, positive cases) and light microscopy (28/83, positive cases). The most prevalent NTD pathogen in the suspected patients was N. gonorrhoeae with 60.24% (50/83) based on real-time PCR diagnosis. Among the positive cases of STI pathogens, Neisseria gonorrhoeae had the highest frequency 49/55 (89.01%) followed by low frequencies of Trichomonas vaginalis 4/55 (7.27%) and Chlamydia trachomatis 1/55 (1.82%). This highlights the high prevalence of N. gonorrhoeae infection in male urethritis patients and a very important misdiagnosis using traditional routine methods in Burkina Faso by medical laboratories. Thus, this situation may negatively impact patients’ personalized treatment and care and public health with the possible rapid emergence of multidrug-resistant strains. This study also highlights the urgent need to optimize culture for the diagnosis of NTD pathogens in Burkina Faso and the usefulness and the need for the introduction of molecular diagnostic methods in routine diagnosis for the detection of NTD pathogens in the medical laboratories in Burkina Faso.展开更多
The numerical dispersion phenomenon in the finite-difference forward modeling simulations of the wave equation significantly affects the imaging accuracy in acoustic reflection logging.This issue is particularly prono...The numerical dispersion phenomenon in the finite-difference forward modeling simulations of the wave equation significantly affects the imaging accuracy in acoustic reflection logging.This issue is particularly pronounced in the reverse time migration(RTM)method used for shear-wave(S-wave)logging imaging.This not only affects imaging accuracy but also introduces ambiguities in the interpretation of logging results.To address this challenge,this study proposes the use of a least-squares difference coefficient optimization algorithm aiming to suppress the numerical dispersion phenomenon in the RTM of S-wave reflection imaging logging.By optimizing the difference coefficients,the high-precision finite-difference algorithm serves as an effective operator for both forward and backward RTM processes.This approach is instrumental in eliminating migration illusions,which are often caused by numerical dispersion.The effectiveness of this optimized algorithm is demonstrated through numerical results,which indicate that it can achieve more accurate forward imaging results across various conditions,including high-and low-velocity strata,and is effective in both large and small spatial grids.The results of processing real data demonstrate that numerical dispersion optimization effectively reduces migration artifacts and diminishes ambiguities in logging interpretations.This optimization offers crucial technical support to the RTM method,enhancing its capability for accurately modeling and imaging S-wave reflections.展开更多
Multi-component seismic exploration technology, combining reflected PP- and converted PS-waves, is an effective tool for solving complicated oil and gas exploration problems. The improvement of converted wave resoluti...Multi-component seismic exploration technology, combining reflected PP- and converted PS-waves, is an effective tool for solving complicated oil and gas exploration problems. The improvement of converted wave resolution is one of the key problems. The main factor affecting converted wave resolution is the absorption of seismic waves in overlying strata. In order to remove the effect of absorption on converted waves, inverse Q filtering is used to improve the resolution. In this paper, we present a method to estimate the S-wave Q values from prestack converted wave gathers. Furthermore, we extend a stable and effective poststack inverse Q filtering method to prestack data which uses wave field continuation along the ray path to compensate for attenuation in prestack common shot PP- and PS-waves. The results of theoretical modeling prove that the method of estimating the S-wave Q values has high precision. The results from synthetic and real data prove that the stable inverse Q filtering method can effectively improve the resolution of prestack PP- and PS-waves.展开更多
Defect inspection of specular curved surface is a challenging job. Taking steel balls for example, a new method based on reflected pattern integrity recognition is put forward. The specular steel ball surfac...Defect inspection of specular curved surface is a challenging job. Taking steel balls for example, a new method based on reflected pattern integrity recognition is put forward. The specular steel ball surface will totally reflect the patterns when it is placed inside a dome-shaped light source, whose inner wall is modified by patterns with certain regular. Distortion or intermittence of reflected pattern will occur at the defective part, which indicates the pattern has lost its integrity. Based on the integrity analysis of reflected pattern images？ surface defects can be revealed. In this paper, a set of concentric circles are used as the pattern and an image processing algorithm is customized to extract the surface defects. Results show that the proposed method is effective for the specular curved surface defect inspection展开更多
Objectives： To understand trends and epidemiology of STDs in Chongqing from 1998 to 2003 and to provide scientific evidence for developing preventive strategies and distributing government health resources effectivel...Objectives： To understand trends and epidemiology of STDs in Chongqing from 1998 to 2003 and to provide scientific evidence for developing preventive strategies and distributing government health resources effectively. Methods： STD case-reporting data collected from 43 counties and districts in Chongqing from 1998 to 2003 were analyzed with STD Data Management Software and Excel Software. Results： A total of 133,323 cases of eight different STDs were reported from 1998-2003. The annual incidence of all eight STDs combined was 71.89/10^5.Generally, reported cases and incidence have decreased since 2001. Although gonorrhoea diagnoses made up a significant proportion of the STD burden, this proportion decreased annually. The proportion of the STD burden attributed to Condyloma accuminatum （CA） was always above 30 percent. The proportions of non-gonoccocal urethritis, genital herpes and syphilis within the combinedSTD burden increased gradually from 1998 to 2003.Reported cases of HIV increased rapidly over this time. A total of 214 HIV cases were reported from 1998 to 2003,the majority of which were among men. For HIV, the maleto-female ratio was 1.17, but CA was found among more women than men. Incidence for all STDs was highest among 20-39 year olds, who accounted for 72.2% of reported infections. The majority of STDs were transmitted through extra-marital intercourse,accounting for 55.3%. Conclusion： The STD epidemic in Chongqing changed from 1998-2003. STD incidence declined, as a result of various factors. The epidemiology of STDs has changed.HIV incidence has increased rapidly. This indicates that the AIDS epidemic has reached a critical period. The results of this study suggest a need for readjusting control measures and redistributing health resources.展开更多
Transmitted ultrasonic wave simulation （TUWS） in a digital core is one of the important elements of digital rock physics and is used to study wave propagation in porous cores and calculate equivalent velocity. When ...Transmitted ultrasonic wave simulation （TUWS） in a digital core is one of the important elements of digital rock physics and is used to study wave propagation in porous cores and calculate equivalent velocity. When simulating wave propagates in a 3D digital core, two additional layers are attached to its two surfaces vertical to the wave-direction and one planar wave source and two receiver-arrays are properly installed. After source excitation, the two receivers then record incident and transmitted waves of the digital rock. Wave propagating velocity, which is the velocity of the digital core, is computed by the picked peak-time difference between the two recorded waves. To evaluate the accuracy of TUWS, a digital core is fully saturated with gas, oil, and water to calculate the corresponding velocities. The velocities increase with decreasing wave frequencies in the simulation frequency band, and this is considered to be the result of scattering. When the pore fluids are varied from gas to oil and finally to water, the velocity-variation characteristics between the different frequencies are similar, thereby approximately following the variation law of velocities obtained from linear elastic statics simulation （LESS）, although their absolute values are different. However, LESS has been widely used. The results of this paper show that the transmission ultrasonic simulation has high relative precision.展开更多
Language is a vehicle for culture. It is also a key component of culture. It not only reflects culture but also influences culture. As a variety of British English,American English,especially American words and expres...Language is a vehicle for culture. It is also a key component of culture. It not only reflects culture but also influences culture. As a variety of British English,American English,especially American words and expressions can reflect American culture from many aspects. This paper studies some typical traits of American culture reflected in words and expressions of American Eng lish.展开更多
Sexually transmitted diseases （STDs） are among the first ten causes of unpleasant diseases in young adult males in developing countries and the second major cause of unpleasant diseases in young adult women. Adolesc...Sexually transmitted diseases （STDs） are among the first ten causes of unpleasant diseases in young adult males in developing countries and the second major cause of unpleasant diseases in young adult women. Adolescents and young adults （15-24 years old） make up only 25% of the sexually active population, but represent almost 50% of all new acquired STDs. In general, STDs are epidemics and present an enormous health and economic consequences. An adequate screening for STDs should be done on a routine basis in every part of the world. Many STDs are asymptomatic and therefore can difficult to control. The purpose of reporting of STDs is to ensure that persons who are infected will be quickly diagnosed and appropriately treated to control the spread of infection and also so that partners are notified, tested and appropriately treated. It is estimated that reported cases of STDs represent only 50%-80% of reportable STD infections in the United States, reflecting limited screening and low disease reporting. High-risk sexual behavior is a highly contributive factor of this process as it often leads to teenage pregnancies and HIV/AIDS. One possible explanation for this behavior is that people do not have enough information about the transmission of STDs or ignore the precautions required for safe sex. Approximately 60% of new HIV infections worldwide occur in young people. The frequency of high-risk behaviors among youths may also be influenced by opportunity to engage in them, particularly the amount of time that they are unsupervised by adults. However, in diagnosing and treating these patients, we can effectively prevent the spread of HIV/AIDS. Individuals infected with STDs are 5-10 times more likely than uninfected individuals to acquire or transmit HIV through sexual contact. The breaking of the genital tract lining or skin creates a portal of entry for HIV and, hence, HIV-infected individuals with other STDs are more likely to shed HIV in their genital secretions. To date, the condom is the most effective method available for males for protection against STDs. It is important to control STDs, and prevention can be the key of this process. Prevention can be achieved through education of the population, identification of symptomatic and asymptomatic people, and effective diagnosis and treatment of these patients and their partners.展开更多
INIRODUCIIONA newly discovered DNA virus,transfusiontransmitted virus (TTV),was reported as a cause ofpost-transfusion hepatitis of unknown etiology inJapan.In order to investigate TTV prevalence insouthern China,a st...INIRODUCIIONA newly discovered DNA virus,transfusiontransmitted virus (TTV),was reported as a cause ofpost-transfusion hepatitis of unknown etiology inJapan.In order to investigate TTV prevalence insouthern China,a study was carried out amongblood donors,patients with liver diseases andhemodialysis to determine the epidemiologicalcharateristics.展开更多
Cancers in solid organ recipients may be classified as donor transmitted,donor derived,de novo or recurrent.The risk of donor-transmitted cancer is very low and can be reduced by careful screening of the donor but can...Cancers in solid organ recipients may be classified as donor transmitted,donor derived,de novo or recurrent.The risk of donor-transmitted cancer is very low and can be reduced by careful screening of the donor but cannot be abolished and,in the United Kingdom series is less than 0.03%.For donors with a known history of cancer,the risks will depend on the nature of the cancer,the interventions given and the interval between diagnosis and organ donation.The risks of cancer transmission must be balanced against the risks of death awaiting a new graft and strict adherence to current guidelines may result increased patient death.Organs from selected patients,even with high-grade central nervous system(CNS)malignancy and after a shunt,can,in some circumstances,be considered.Of potential donors with non-CNS cancers,whether organs may be safely used again depends on the nature of the cancer,the treatment and interval.Data are scarce about the most appropriate treatment when donor transmitted cancer is diagnosed:sometimes substitution of agents and reduction of the immunosuppressive load may be adequate and the impact of graft removal should be considered but not always indicated.Liver al-lograft recipients are at increased risk of some de novo cancers,especially those grafted for alcohol-related liver disease and hepatitis C virus infection.The risk of lymphoproliferative disease and cancers of the skin,upper airway and bowel are increased but not breast.Recipients should be advised to avoid risk behavior and monitored appropriately.展开更多
A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater （QCB） in comparison with those of semi-circular breakwater （SCB...A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater （QCB） in comparison with those of semi-circular breakwater （SCB）. Based on regular wave tests, the reflection and transmission characteristics of QCB are analyzed and a few influencing factors are investigated. Then, the wave energy dissipation as wave passing over the breakwater is discussed based on the hydraulic coefficients of QCB and SCB. In irregular wave experiments, the reflection coefficients of QCB and their spectrums are studied. Finally, the comparisons between the experimental results and numerical simulations for QCB under regular and irregular wave conditions are presented.展开更多
In this paper,a sexually transmitted disease model is proposed on complex networks,where contacts between humans are treated as a scale-free social network.There are three groups in our model,which are dangerous male,...In this paper,a sexually transmitted disease model is proposed on complex networks,where contacts between humans are treated as a scale-free social network.There are three groups in our model,which are dangerous male,non-dangerous male,and female.By mathematical analysis,we obtain the basic reproduction number for the existence of endemic equilibrium and study the effects of various immunization schemes about different groups.Furthermore,numerical simulations are undertaken to verify more conclusions.展开更多
The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge memory consumption of the gradient preconditioning algorithms based on the Hessian matrix. However, the accuracy of thi...The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge memory consumption of the gradient preconditioning algorithms based on the Hessian matrix. However, the accuracy of this approach is prone to be influ- enced by the energy of reflected waves. To tackle this problem, the paper proposes a new gradient preconditioning method based on the energy of transmitted waves. The approach scales the gradient through a precondition factor, which is calculated by the ‘ap- proximate transmission wavefield’ simulation based on the nonreflecting acoustic wave equation. The method requires no computing nor storing of the Hessian matrix and its inverse matrix. Furthermore, the proposed method can effectively eliminate the effects of geometric spreading and disproportionality in the gradient illumination. The results of model experiments show that the time-domain full waveform inversion (FWI) using the gradient preconditioning based on transmitted wave energy can achieve higher inversion accuracy for deep high-velocity bodies and their underlying strata in comparison with the one using the gradient preconditioning based on seismic wave energy. The field marine seismic data test shows that our proposed method is also highly applicable to the FWI of field marine seismic data.展开更多
Observations are presented from experiments and calculations where a laminar spherical CH4/air flame is perturbed successively by incident and reflected shock waves. The experiments are performed in a standard shock t...Observations are presented from experiments and calculations where a laminar spherical CH4/air flame is perturbed successively by incident and reflected shock waves. The experiments are performed in a standard shock tube arrangement, in which a high-speed shadowgraph imaging system is used to record evolutions of the flame. Numerical simulations are conducted by using second-order wave propagation algorithms, based on two-dimensional axisymmetric Navier-Stokes equations with detailed chemical reactions. Qualitative agreements are obtained between the experimental and numerical results. Under actions of incident shock waves, Richtmyer-Meshkov instability responsible for the flame deformation is induced in the flame, and the distoned flame takes a barrel shape. Then, under subsequent actions of the shock wave reflected from a planar wall, the flame takes an inclined non-symmetrical kidney shape in a symmetric cross section, which means a mushroom-like shape of the flame comes finally into being. The vorticity direction in the ring cap has been altered by the reflected shock＇s action, which makes the head of the mushroom-like flame extend quickly to the side wall.展开更多
The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitiv...The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.展开更多
This study aims to compare the prevalence of sexually transmitted infections(STIs)with semen quality in men from couples with primary and secondary infertility.Semen samples were collected from 133 men who requested f...This study aims to compare the prevalence of sexually transmitted infections(STIs)with semen quality in men from couples with primary and secondary infertility.Semen samples were collected from 133 men who requested fertility evaluation.Seminal tract infection with Ureaplasma spp.(UU),Mycoplasma hominis(MH),Mycoplasma genitalium(MG),Chlamydia trachomatis(CT),Neisseria gonorrhoeae(NG),and herpes simplex virus-2(HSV-2)was assessed by PCR-based diagnostic assays.Among all patients,the prevalence of STIs was higher in men from couples with primary infertility than that in men from couples with secondary infertility(39.7%vs 21.7%,P=0.03).The prevalence of UU was 28.8%and 13.3%in men from couples with primary and secondary infertility,respectively.Men from couples with primary infertility were more likely to be positive for UU than men from couples with secondary infertility(P=0.04).Regarding the UU subtype,the prevalence of Ureaplasma urealyticum(Uuu)and Ureaplasma parvum(Uup;including Uup1,Uup3,Uup6,and Uup14)did not differ between the two groups.No associations between the prevalence rates of MH,MG,and CT were found in men from either infertility group.A lower sperm concentration was associated with STI pathogen positivity in men with primary infertility according to the crude model(P=0.04).The crude and adjusted models showed that semen volume(both P=0.03)and semen leukocyte count(both P=0.02)were independently associated with secondary infertility.These findings suggest the importance of classifying the type of infertility during routine diagnosis of seminal tract infections.展开更多
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education of China (Grant No. 2007[24])supported by Science and Technology Project of Dalian (Grant No. 2008A16GX248)
文摘Surface or submerged horizontal or vertical plate can be considered as a new concept breakwater. This paper investigates the wave-plate interaction of this type of breakwater by use of the boundary element method. The relationships of wave transmitted and reflected among plate thickness, submergence and length are carefully studied by numerical simulation. It is shown that： （1） The transmitted coefficients of submerged horizontal plate or vertical plate will become larger with the increase of plate thickness and reduce rapidly with the decrease of plate submergence. （2） Both surface horizontal and vertical plate are efficient for intermediate and short wave elimination, but vertical plate is more effective. （3） Submerged horizontal plate can act more effectively than submerged vertical plate does. With all wave frequencies, the vertical plate almost has no wave elimination effect.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61431010 and 61501350)the National Key Basic Research Program of China(Grant No.2014CB340203)
文摘A study has been made on the reflected and transmitted powers generated when an arbitrarily polarized plane wave impinges at a planar interface separating an isotropic achiral medium(IAM) and an isotropic chiral medium(ICM). It follows that the theoretical formulas are derived for the normalized reflection and transmission powers from an IAM–ICM interface for an arbitrary polarized incident wave, and those at an ICM–IAM interface for right-hand circularly polarized(RCP) or left-hand circularly polarized(LCP) incident wave are also obtained. The behavior of the reflected and transmitted waves in different cases is studied, and the dependence of the reflection/transmission of the incident wave on the incident angle and the parameters of the media is investigated in detail. Our numerical results show that high transmission is exhibited under the impedance matching condition and the incident wave can be split into two waves of the same circular polarization state in the case of the ICM–IAM interface, which indicates that circular polarizing beam splitter is achieved.
基金Project supported by the National Basic Research Program of China (973 Program) (Grant Nos 2007CB310408 and2006CB302901)the National Natural Science Foundation of China (Grant No 10804077)+2 种基金Science Foundation of Beijing Municipal Commission of Education (Grant No KM200910028006)Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipalitysupported by State Key Laboratory of Functional Materials for Informatics,Shanghai Institute of Microsystem and Information Technology,the Chinese Academy of Sciences
文摘Femtosecond pump-terahertz probe studies of carrier dynamics in semi-insulating CaAs have been investigated in detail for various pump powers. It is observed that, at high pump powers, the reflection peaks flip to the opposite polarity and dramatically enhance as the pump arrival time approaches the reflected wave of the terahertz pulse. The abnormal polarity-flip and enhancement can be interpreted by the pump-induced enhancement in the photoconductivity of GaAs and half-wave loss. Moreover, the carrier relaxation processes and surface states filling in GaAs are also studied in these measurements.
基金supported by the Yunnan Provincial Key Laboratory of Clinical Virology(No.202002AG070062)the Key Projects of Yunnan Province Science and Technology Department(No.202302AA310044)the National Natural Science Foundation of China(No.82060664).
文摘This study primarily aimed to investigate the prevalence of human papillomavirus(HPV)and other common pathogens of sexually transmitted infections(STIs)in spermatozoa of infertile men and their effects on semen parameters.These pathogens included Ureaplasma urealyticum,Ureaplasma parvum,Chlamydia trachomatis,Mycoplasma genitalium,herpes simplex virus 2,Neisseria gonorrhoeae,Enterococcus faecalis,Streptococcus agalactiae,Pseudomonas aeruginosa,and Staphylococcus aureus.A total of 1951 men of infertile couples were recruited between 23 March 2023,and 17 May 2023,at the Department of Reproductive Medicine of The First People’s Hospital of Yunnan Province(Kunming,China).Multiplex polymerase chain reaction and capillary electrophoresis were used for HPV genotyping.Polymerase chain reaction and electrophoresis were also used to detect the presence of other STIs.The overall prevalence of HPV infection was 12.4%.The top five prevalent HPV subtypes were types 56,52,43,16,and 53 among those tested positive for HPV.Other common infections with high prevalence rates were Ureaplasma urealyticum(28.3%),Ureaplasma parvum(20.4%),and Enterococcus faecalis(9.5%).The prevalence rates of HPV coinfection with Ureaplasma urealyticum,Ureaplasma parvum,Chlamydia trachomatis,Mycoplasma genitalium,herpes simplex virus 2,Neisseria gonorrhoeae,Enterococcus faecalis,Streptococcus agalactiae,and Staphylococcus aureus were 24.8%,25.4%,10.6%,6.4%,2.4%,7.9%,5.9%,0.9%,and 1.3%,respectively.The semen volume and total sperm count were greatly decreased by HPV infection alone.Coinfection with HPV and Ureaplasma urealyticum significantly reduced sperm motility and viability.Our study shows that coinfection with STIs is highly prevalent in the semen of infertile men and that coinfection with pathogens can seriously affect semen parameters,emphasizing the necessity of semen screening for STIs.
文摘Sexually transmitted infections (STIs) represent a public health problem due to their high prevalence worldwide and the emergence of multidrug resistance of responsible microorganisms. Medical laboratory diagnosis of sexually transmitted genital infections by traditional methods as culture remains extremely delicate, difficult or impossible (to find extremely fragile organisms that can be cultured). Thus, molecular techniques constitute an alternative to improve accurate diagnostic, personalized patient treatment, and public health. A total of 83 clinical samples including urethral discharge and urine samples from individual patients with symptoms of urethritis received were analyzed using traditional methods and a commercial real-time PCR (qPCR) method. Out of 83 urethritis patients, n = 55 (66.26%) were positive for at least one of the STI pathogens detected by qPCR. qPCR assay was more sensitive (50/83, positive cases) compared to culture (15/83, positive cases) and light microscopy (28/83, positive cases). The most prevalent NTD pathogen in the suspected patients was N. gonorrhoeae with 60.24% (50/83) based on real-time PCR diagnosis. Among the positive cases of STI pathogens, Neisseria gonorrhoeae had the highest frequency 49/55 (89.01%) followed by low frequencies of Trichomonas vaginalis 4/55 (7.27%) and Chlamydia trachomatis 1/55 (1.82%). This highlights the high prevalence of N. gonorrhoeae infection in male urethritis patients and a very important misdiagnosis using traditional routine methods in Burkina Faso by medical laboratories. Thus, this situation may negatively impact patients’ personalized treatment and care and public health with the possible rapid emergence of multidrug-resistant strains. This study also highlights the urgent need to optimize culture for the diagnosis of NTD pathogens in Burkina Faso and the usefulness and the need for the introduction of molecular diagnostic methods in routine diagnosis for the detection of NTD pathogens in the medical laboratories in Burkina Faso.
基金supported by Scientific Research and Technology Development Project of CNPC(2021DJ4002,2022DJ3908).
文摘The numerical dispersion phenomenon in the finite-difference forward modeling simulations of the wave equation significantly affects the imaging accuracy in acoustic reflection logging.This issue is particularly pronounced in the reverse time migration(RTM)method used for shear-wave(S-wave)logging imaging.This not only affects imaging accuracy but also introduces ambiguities in the interpretation of logging results.To address this challenge,this study proposes the use of a least-squares difference coefficient optimization algorithm aiming to suppress the numerical dispersion phenomenon in the RTM of S-wave reflection imaging logging.By optimizing the difference coefficients,the high-precision finite-difference algorithm serves as an effective operator for both forward and backward RTM processes.This approach is instrumental in eliminating migration illusions,which are often caused by numerical dispersion.The effectiveness of this optimized algorithm is demonstrated through numerical results,which indicate that it can achieve more accurate forward imaging results across various conditions,including high-and low-velocity strata,and is effective in both large and small spatial grids.The results of processing real data demonstrate that numerical dispersion optimization effectively reduces migration artifacts and diminishes ambiguities in logging interpretations.This optimization offers crucial technical support to the RTM method,enhancing its capability for accurately modeling and imaging S-wave reflections.
基金supported by the 863 Program(Grant No.2007AA06Z218)
文摘Multi-component seismic exploration technology, combining reflected PP- and converted PS-waves, is an effective tool for solving complicated oil and gas exploration problems. The improvement of converted wave resolution is one of the key problems. The main factor affecting converted wave resolution is the absorption of seismic waves in overlying strata. In order to remove the effect of absorption on converted waves, inverse Q filtering is used to improve the resolution. In this paper, we present a method to estimate the S-wave Q values from prestack converted wave gathers. Furthermore, we extend a stable and effective poststack inverse Q filtering method to prestack data which uses wave field continuation along the ray path to compensate for attenuation in prestack common shot PP- and PS-waves. The results of theoretical modeling prove that the method of estimating the S-wave Q values has high precision. The results from synthetic and real data prove that the stable inverse Q filtering method can effectively improve the resolution of prestack PP- and PS-waves.
基金Tianjin Research Program of Application Foundation and Advanced Technology(No.14JCYBJC18600,No.14JCZDJC39700)National Key Scientific Instrument and Equipment Development Project(No.2013YQ17053903)
文摘Defect inspection of specular curved surface is a challenging job. Taking steel balls for example, a new method based on reflected pattern integrity recognition is put forward. The specular steel ball surface will totally reflect the patterns when it is placed inside a dome-shaped light source, whose inner wall is modified by patterns with certain regular. Distortion or intermittence of reflected pattern will occur at the defective part, which indicates the pattern has lost its integrity. Based on the integrity analysis of reflected pattern images？ surface defects can be revealed. In this paper, a set of concentric circles are used as the pattern and an image processing algorithm is customized to extract the surface defects. Results show that the proposed method is effective for the specular curved surface defect inspection
文摘Objectives： To understand trends and epidemiology of STDs in Chongqing from 1998 to 2003 and to provide scientific evidence for developing preventive strategies and distributing government health resources effectively. Methods： STD case-reporting data collected from 43 counties and districts in Chongqing from 1998 to 2003 were analyzed with STD Data Management Software and Excel Software. Results： A total of 133,323 cases of eight different STDs were reported from 1998-2003. The annual incidence of all eight STDs combined was 71.89/10^5.Generally, reported cases and incidence have decreased since 2001. Although gonorrhoea diagnoses made up a significant proportion of the STD burden, this proportion decreased annually. The proportion of the STD burden attributed to Condyloma accuminatum （CA） was always above 30 percent. The proportions of non-gonoccocal urethritis, genital herpes and syphilis within the combinedSTD burden increased gradually from 1998 to 2003.Reported cases of HIV increased rapidly over this time. A total of 214 HIV cases were reported from 1998 to 2003,the majority of which were among men. For HIV, the maleto-female ratio was 1.17, but CA was found among more women than men. Incidence for all STDs was highest among 20-39 year olds, who accounted for 72.2% of reported infections. The majority of STDs were transmitted through extra-marital intercourse,accounting for 55.3%. Conclusion： The STD epidemic in Chongqing changed from 1998-2003. STD incidence declined, as a result of various factors. The epidemiology of STDs has changed.HIV incidence has increased rapidly. This indicates that the AIDS epidemic has reached a critical period. The results of this study suggest a need for readjusting control measures and redistributing health resources.
基金supported by the Open Fund of the Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University)the Ministry of Education(No.K2014-06)the Reservoir Geophysical Research Center at Yangtze University
文摘Transmitted ultrasonic wave simulation （TUWS） in a digital core is one of the important elements of digital rock physics and is used to study wave propagation in porous cores and calculate equivalent velocity. When simulating wave propagates in a 3D digital core, two additional layers are attached to its two surfaces vertical to the wave-direction and one planar wave source and two receiver-arrays are properly installed. After source excitation, the two receivers then record incident and transmitted waves of the digital rock. Wave propagating velocity, which is the velocity of the digital core, is computed by the picked peak-time difference between the two recorded waves. To evaluate the accuracy of TUWS, a digital core is fully saturated with gas, oil, and water to calculate the corresponding velocities. The velocities increase with decreasing wave frequencies in the simulation frequency band, and this is considered to be the result of scattering. When the pore fluids are varied from gas to oil and finally to water, the velocity-variation characteristics between the different frequencies are similar, thereby approximately following the variation law of velocities obtained from linear elastic statics simulation （LESS）, although their absolute values are different. However, LESS has been widely used. The results of this paper show that the transmission ultrasonic simulation has high relative precision.
文摘Language is a vehicle for culture. It is also a key component of culture. It not only reflects culture but also influences culture. As a variety of British English,American English,especially American words and expressions can reflect American culture from many aspects. This paper studies some typical traits of American culture reflected in words and expressions of American Eng lish.
文摘Sexually transmitted diseases （STDs） are among the first ten causes of unpleasant diseases in young adult males in developing countries and the second major cause of unpleasant diseases in young adult women. Adolescents and young adults （15-24 years old） make up only 25% of the sexually active population, but represent almost 50% of all new acquired STDs. In general, STDs are epidemics and present an enormous health and economic consequences. An adequate screening for STDs should be done on a routine basis in every part of the world. Many STDs are asymptomatic and therefore can difficult to control. The purpose of reporting of STDs is to ensure that persons who are infected will be quickly diagnosed and appropriately treated to control the spread of infection and also so that partners are notified, tested and appropriately treated. It is estimated that reported cases of STDs represent only 50%-80% of reportable STD infections in the United States, reflecting limited screening and low disease reporting. High-risk sexual behavior is a highly contributive factor of this process as it often leads to teenage pregnancies and HIV/AIDS. One possible explanation for this behavior is that people do not have enough information about the transmission of STDs or ignore the precautions required for safe sex. Approximately 60% of new HIV infections worldwide occur in young people. The frequency of high-risk behaviors among youths may also be influenced by opportunity to engage in them, particularly the amount of time that they are unsupervised by adults. However, in diagnosing and treating these patients, we can effectively prevent the spread of HIV/AIDS. Individuals infected with STDs are 5-10 times more likely than uninfected individuals to acquire or transmit HIV through sexual contact. The breaking of the genital tract lining or skin creates a portal of entry for HIV and, hence, HIV-infected individuals with other STDs are more likely to shed HIV in their genital secretions. To date, the condom is the most effective method available for males for protection against STDs. It is important to control STDs, and prevention can be the key of this process. Prevention can be achieved through education of the population, identification of symptomatic and asymptomatic people, and effective diagnosis and treatment of these patients and their partners.
文摘INIRODUCIIONA newly discovered DNA virus,transfusiontransmitted virus (TTV),was reported as a cause ofpost-transfusion hepatitis of unknown etiology inJapan.In order to investigate TTV prevalence insouthern China,a study was carried out amongblood donors,patients with liver diseases andhemodialysis to determine the epidemiologicalcharateristics.
文摘Cancers in solid organ recipients may be classified as donor transmitted,donor derived,de novo or recurrent.The risk of donor-transmitted cancer is very low and can be reduced by careful screening of the donor but cannot be abolished and,in the United Kingdom series is less than 0.03%.For donors with a known history of cancer,the risks will depend on the nature of the cancer,the interventions given and the interval between diagnosis and organ donation.The risks of cancer transmission must be balanced against the risks of death awaiting a new graft and strict adherence to current guidelines may result increased patient death.Organs from selected patients,even with high-grade central nervous system(CNS)malignancy and after a shunt,can,in some circumstances,be considered.Of potential donors with non-CNS cancers,whether organs may be safely used again depends on the nature of the cancer,the treatment and interval.Data are scarce about the most appropriate treatment when donor transmitted cancer is diagnosed:sometimes substitution of agents and reduction of the immunosuppressive load may be adequate and the impact of graft removal should be considered but not always indicated.Liver al-lograft recipients are at increased risk of some de novo cancers,especially those grafted for alcohol-related liver disease and hepatitis C virus infection.The risk of lymphoproliferative disease and cancers of the skin,upper airway and bowel are increased but not breast.Recipients should be advised to avoid risk behavior and monitored appropriately.
基金supported by the National Natural Science Foundation of China (Grant No. 50779045)the Open Foundation of State Key Laboratory of Hydraulics and Mountain River Engineering (Grant No. 0710)+2 种基金the National Science Foundation for Post-Doctoral Scientists of China (Grant No. 20080440681)the Natural Science Foundation of Tianjin, China (Grant No. 10JCYBJC03700)the Scientific and Technologic Development Foundation of the Higher Education Institutions of Tianjin,China (Grant No. 20080906)
文摘A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater （QCB） in comparison with those of semi-circular breakwater （SCB）. Based on regular wave tests, the reflection and transmission characteristics of QCB are analyzed and a few influencing factors are investigated. Then, the wave energy dissipation as wave passing over the breakwater is discussed based on the hydraulic coefficients of QCB and SCB. In irregular wave experiments, the reflection coefficients of QCB and their spectrums are studied. Finally, the comparisons between the experimental results and numerical simulations for QCB under regular and irregular wave conditions are presented.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10901145)the Natural Science Foundation of Shanxi Province,China(Grant Nos. 2009011005-1 and 2012011002-1)the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,China
文摘In this paper,a sexually transmitted disease model is proposed on complex networks,where contacts between humans are treated as a scale-free social network.There are three groups in our model,which are dangerous male,non-dangerous male,and female.By mathematical analysis,we obtain the basic reproduction number for the existence of endemic equilibrium and study the effects of various immunization schemes about different groups.Furthermore,numerical simulations are undertaken to verify more conclusions.
基金support of the NSFCShandong Joint Fund for Marine Science Research Centers (No. U1606401)the National Natural Science Foundation of China (Nos. 41574105 and 41704114)+1 种基金the National Science and Technology Major Project of China (No.2016ZX05027-002)Taishan Scholar Project Funding (No. tspd20161007)
文摘The gradient preconditioning approach based on seismic wave energy can effectively avoid the huge memory consumption of the gradient preconditioning algorithms based on the Hessian matrix. However, the accuracy of this approach is prone to be influ- enced by the energy of reflected waves. To tackle this problem, the paper proposes a new gradient preconditioning method based on the energy of transmitted waves. The approach scales the gradient through a precondition factor, which is calculated by the ‘ap- proximate transmission wavefield’ simulation based on the nonreflecting acoustic wave equation. The method requires no computing nor storing of the Hessian matrix and its inverse matrix. Furthermore, the proposed method can effectively eliminate the effects of geometric spreading and disproportionality in the gradient illumination. The results of model experiments show that the time-domain full waveform inversion (FWI) using the gradient preconditioning based on transmitted wave energy can achieve higher inversion accuracy for deep high-velocity bodies and their underlying strata in comparison with the one using the gradient preconditioning based on seismic wave energy. The field marine seismic data test shows that our proposed method is also highly applicable to the FWI of field marine seismic data.
基金supported by the National Natural Science Foundation of China (10472047)the Open Fund of State Key Laboratory of Explosion Science Technology, Beijing University of Science and Technology (KFJJ06-3)
文摘Observations are presented from experiments and calculations where a laminar spherical CH4/air flame is perturbed successively by incident and reflected shock waves. The experiments are performed in a standard shock tube arrangement, in which a high-speed shadowgraph imaging system is used to record evolutions of the flame. Numerical simulations are conducted by using second-order wave propagation algorithms, based on two-dimensional axisymmetric Navier-Stokes equations with detailed chemical reactions. Qualitative agreements are obtained between the experimental and numerical results. Under actions of incident shock waves, Richtmyer-Meshkov instability responsible for the flame deformation is induced in the flame, and the distoned flame takes a barrel shape. Then, under subsequent actions of the shock wave reflected from a planar wall, the flame takes an inclined non-symmetrical kidney shape in a symmetric cross section, which means a mushroom-like shape of the flame comes finally into being. The vorticity direction in the ring cap has been altered by the reflected shock＇s action, which makes the head of the mushroom-like flame extend quickly to the side wall.
基金supported by funding from the National Natural Science Foundation of China (grant no. 41904061)China Postdoctoral Science Foundation (grant no. 2018M640742)
文摘The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.
基金supported by the National Key Research and Development Project(2019YFA0802600)the National Natural Science Foundation of China(No.81901543,81901545,81971333,82001495,32002354)+2 种基金the Fundamental Research Funds for the Central Universities(WK9110000063)the State Key Laboratory of Reproductive Medicine(SKLRM-K201904)the Natural Science Foundation of Anhui Provincial of China(1908085QH315).
文摘This study aims to compare the prevalence of sexually transmitted infections(STIs)with semen quality in men from couples with primary and secondary infertility.Semen samples were collected from 133 men who requested fertility evaluation.Seminal tract infection with Ureaplasma spp.(UU),Mycoplasma hominis(MH),Mycoplasma genitalium(MG),Chlamydia trachomatis(CT),Neisseria gonorrhoeae(NG),and herpes simplex virus-2(HSV-2)was assessed by PCR-based diagnostic assays.Among all patients,the prevalence of STIs was higher in men from couples with primary infertility than that in men from couples with secondary infertility(39.7%vs 21.7%,P=0.03).The prevalence of UU was 28.8%and 13.3%in men from couples with primary and secondary infertility,respectively.Men from couples with primary infertility were more likely to be positive for UU than men from couples with secondary infertility(P=0.04).Regarding the UU subtype,the prevalence of Ureaplasma urealyticum(Uuu)and Ureaplasma parvum(Uup;including Uup1,Uup3,Uup6,and Uup14)did not differ between the two groups.No associations between the prevalence rates of MH,MG,and CT were found in men from either infertility group.A lower sperm concentration was associated with STI pathogen positivity in men with primary infertility according to the crude model(P=0.04).The crude and adjusted models showed that semen volume(both P=0.03)and semen leukocyte count(both P=0.02)were independently associated with secondary infertility.These findings suggest the importance of classifying the type of infertility during routine diagnosis of seminal tract infections.
