期刊文献+
共找到245,567篇文章
< 1 2 250 >
每页显示 20 50 100
Assessment of Wet Season Precipitation in the Central United States by the Regional Climate Simulation of the WRFG Member in NARCCAP and Its Relationship with Large-Scale Circulation Biases 被引量:1
1
作者 Yating ZHAO Ming XUE +2 位作者 Jing JIANG Xiao-Ming HU Anning HUANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第4期619-638,共20页
Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss pos... Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios. 展开更多
关键词 NARCCAP Central united states PRECIPITATION low-level jet large-scale environment diurnal variation
下载PDF
Temporal Variability of Tropospheric NO_(2)over Cities in the United States,Western Europe and China from 2005 to 2022
2
作者 ZHANG Qianqian 《Chinese Geographical Science》 SCIE CSCD 2024年第6期983-992,共10页
Anthropogenic Nitrogen oxides(NO_(x)=NO_(2)+NO)emissions are highly concentrated in urban area,and the weekly cycles,seasonal patterns and long-term trends of tropospheric NO_(2)columns over cities differ from region ... Anthropogenic Nitrogen oxides(NO_(x)=NO_(2)+NO)emissions are highly concentrated in urban area,and the weekly cycles,seasonal patterns and long-term trends of tropospheric NO_(2)columns over cities differ from region to region due to different emission sectoral compositions and human activities.In this study,we used satellite observed tropospheric NO_(2)column data to compare the longand short-term NO_(2)column density time series over cities in the United Sates(the U.S.),western Europe and China.The results showed that in all the targeted cities,the outbreak of the Corona Virus Disease in 2019(COVID-19)moved the December peak of the city-level NO_(2)columns forward to November and October or even earlier in 2020 and 2021.On weekly level,cities in the U.S.show the lowest NO_(2)columns ratio on weekend/work day,then come the western European cities,and a weak weekly pattern is seen in Chinese cities.For all the cites,we find a higher weekend/work day NO_(2)ratio in cold seasons than in warm seasons,indicating a higher contribution from NOx emission sectors of residential,industry and power plants in the warm seasons.In the long-term,NO_(2)columns over the U.S.and western European cities declined by a fraction twice that of the regional mean level from 2004 to 2021.In China,NO_(2)columns started to decrease since 2012,at a similar rate between the city and regional level.This work confirms the importance to quantify and control NOx emissions from cities. 展开更多
关键词 NO_(2)columns urban region weekly cycle seasonal pattern long-term trend united states western Europe China
下载PDF
Geologic characteristics,exploration and production progress of shale oil and gas in the United States:An overview
3
作者 MCMAHON T P LARSON T E +1 位作者 ZHANG T SHUSTER M 《Petroleum Exploration and Development》 SCIE 2024年第4期925-948,共24页
We present a systematic summary of the geological characteristics,exploration and development history and current state of shale oil and gas in the United States.The hydrocarbon-rich shales in the major shale basins o... We present a systematic summary of the geological characteristics,exploration and development history and current state of shale oil and gas in the United States.The hydrocarbon-rich shales in the major shale basins of the United States are mainly developed in six geological periods:Middle Ordovician,Middle-Late Devonian,Early Carboniferous(Middle-Late Mississippi),Early Permian,Late Jurassic,and Late Cretaceous(Cenomanian-Turonian).Depositional environments for these shales include intra-cratonic basins,foreland basins,and passive continental margins.Paleozoic hydrocarbon-rich shales are mainly developed in six basins,including the Appalachian Basin(Utica and Marcellus shales),Anadarko Basin(Woodford Shale),Williston Basin(Bakken Shale),Arkoma Basin(Fayetteville Shale),Fort Worth Basin(Barnett Shale),and the Wolfcamp and Leonardian Spraberry/Bone Springs shale plays of the Permian Basin.The Mesozoic hydrocarbon-rich shales are mainly developed on the margins of the Gulf of Mexico Basin(Haynesville and Eagle Ford)or in various Rocky Mountain basins(Niobrara Formation,mainly in the Denver and Powder River basins).The detailed analysis of shale plays reveals that the shales are different in facies and mineral components,and"shale reservoirs"are often not shale at all.The United States is abundant in shale oil and gas,with the in-place resources exceeding 0.246×10^(12)t and 290×10^(12)m^(3),respectively.Before the emergence of horizontal well hydraulic fracturing technology to kick off the"shale revolution",the United States had experienced two decades of exploration and production practices,as well as theory and technology development.In 2007-2023,shale oil and gas production in the United States increased from approximately 11.2×10^(4)tons of oil equivalent per day(toe/d)to over 300.0×10^(4)toe/d.In 2017,the shale oil and gas production exceeded the conventional oil and gas production in the country.In 2023,the contribution from shale plays to the total U.S.oil and gas production remained above 60%.The development of shale oil and gas has largely been driven by improvements in drilling and completion technologies,with much of the recent effort focused on“cube development”or“co-development”.Other efforts to improve productivity and efficiency include refracturing,enhanced oil recovery,and drilling of“U-shaped”wells.Given the significant resources base and continued technological improvements,shale oil and gas production will continue to contribute significant volumes to total U.S.hydrocarbon production. 展开更多
关键词 united states shale oil shale gas shale reservoirs unconventional reservoirs oil and gas production resource assessment
下载PDF
Characteristics of patients with Wilson disease in the United States: An insurance claims database study
4
作者 Thomas Daniel-Robin Pradeep Kumar +1 位作者 Bernard Benichou Jean-Philippe Combal 《World Journal of Hepatology》 2024年第5期791-799,共9页
BACKGROUND Wilson disease(WD)is a progressive,potentially fatal degenerative disease affecting the liver and central nervous system.Given its low prevalence,collecting data on large cohorts of patients with WD is chal... BACKGROUND Wilson disease(WD)is a progressive,potentially fatal degenerative disease affecting the liver and central nervous system.Given its low prevalence,collecting data on large cohorts of patients with WD is challenging.Comprehensive insur-ance claims databases provide powerful tools to collect retrospective data on large numbers of patients with rare diseases.AIM To describe patients with WD in the United States,their treatment and clinical outcome,using a large insurance claims database.METHODS This retrospective,longitudinal study was performed in the Clarivate Real-World Data Product database.All patients with≥2 claims associated with an Interna-tional Classification of Diseases 10(ICD-10)diagnostic code for WD(E83.01)between 2016 and 2021 were included and followed until death or study end.Patients were divided into two groups by whether or not they were documented to have received a specific treatment for WD.Clinical manifestations,hospital-isations,liver transplantation and death were documented.RESULTS Overall,5376 patients with an ICD-10 diagnostic code for WD were identified.The mean age at inclusion was 41.2 years and 52.0%were men.A specific WD treatment was documented for 885 patients(15.1%),although the number of patients taking zinc salts may be underestimated due to over the counter purchase.At inclusion,the mean age of patients with a documented treatment was 36.6±17.8 years vs 42.2±19.6 years in those without a documented treatment.During follow-up,273 patients(5.1%)died.Compared with the American general population,the standardised mortality ratio was 2.19.The proportion of patients with a documented WD-specific treatment who died during follow-up was 4.0%and the mean age at death 52.7 years.CONCLUSION Patients treated for WD in the United States had an excess early mortality compared with the American population.These findings indicate that there is a significant unmet need for effective treatment for WD in the United States. 展开更多
关键词 Wilson disease MORTALITY TREATMENT Copper chelators Zinc acetate united states
下载PDF
Travel-Limiting Disabilities in the United States: Why Accessibility Matters?
5
作者 Oluwaseun Ibukun Bhuiyan Alam 《Journal of Transportation Technologies》 2024年第3期336-357,共22页
This study evaluates the distribution of travel-limiting disabilities across genders and geographic locations in the United States. This study aims to describe and compare the socioeconomic and demographic variables o... This study evaluates the distribution of travel-limiting disabilities across genders and geographic locations in the United States. This study aims to describe and compare the socioeconomic and demographic variables of the people with and without travel-limiting disabilities across geographic locations and gender. The study further evaluates the trip purpose and impact of Covid-19 fourth wave pandemic on the use of public transit and travel to physical workplace for the people with and without travel-limiting disabilities across gender and geographic locations. The study uses the 2022 weighted National Household Travel Survey dataset and employs descriptive statistics. Results reaffirm the findings from previous literature that there are more people with travel-limiting disabilities in urban areas and among women. Over 50 percent of people aged 65 and above have a form of travel-limiting disabilities. The most trip for people with travel-limiting disabilities is made for shopping and medical purposes. Across all categories, rural areas, urban areas, male and female for the people without travel-limiting disabilities, COVID-19 fourth wave did not change the pattern of trips made to physical workplace as pre-COVID-19 era. This pattern is also observable for the people with travel-limiting disabilities in rural and urban areas. Females with travel-limiting disabilities reported making less trips to physical workplaces while male reported doing the same as before COVID-19 era. The study concludes that the quantification of travel-limiting disabilities across geographic location and gender is vital in disability study and could drive policy implementation for improved accessibility for the vulnerable population. 展开更多
关键词 National Household Travel Survey united states Travel-Limiting Disabilities Descriptive Statistics Covid-19 Disability Study
下载PDF
Maternal Mortality Rates among Im/Migrant Populations in the United States
6
作者 Tessa Peredy Mary Greenwald +4 位作者 Katy Doughty Fachon Fiona Danaher Rashmi Jasrasaria Samantha Truong Annekathryn Goodman 《Open Journal of Obstetrics and Gynecology》 2024年第8期1161-1175,共15页
Introduction: Maternal mortality rates have more than doubled in the U.S over the last two decades, making it one of the few places in the world where maternal mortality is increasing. Differences in maternal mortalit... Introduction: Maternal mortality rates have more than doubled in the U.S over the last two decades, making it one of the few places in the world where maternal mortality is increasing. Differences in maternal mortality among certain races and ethnicities are known but few studies examine maternal mortality among immigrants. Since immigrants represent 13.7% of the U.S. population, it is essential to examine immigrant subsets to understand maternal mortality among this vulnerable population. Methods: A literature search identified 318 articles on maternal mortality and immigrants, with 12 articles from the U.S. The keywords included maternal mortality, United States, migrants, asylum seekers, immigrants, and disparities. Maternal mortality statistics were obtained from the World Health Organization and Center for Disease Control. Results: Studies analyzed in this review found an overall lower maternal mortality rate among immigrant women compared to U.S.-born women, except for Hispanic immigrant women. Black women had the highest maternal mortality rate, regardless of immigration status. Conclusion: Although the literature points to lower maternal mortality among immigrants, the data is still somewhat mixed, making it challenging to draw comprehensive conclusions. Additional research examining maternal mortality among Im/migrants in the U.S. is needed to guide future training among healthcare professionals and policymakers. 展开更多
关键词 Maternal Mortality Im/Migrant Reproductive Health united states
下载PDF
Entropy variances of pure coherent states in the diffusion channel
7
作者 Wei-Feng Wu Yong Fang Peng Fu 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期384-388,共5页
Using the operator correspondence of the real and fictious modes in the thermo entangled state representation, wesolve the quantum master equation describing the diffusion channel and obtain the Kraus operator-sum rep... Using the operator correspondence of the real and fictious modes in the thermo entangled state representation, wesolve the quantum master equation describing the diffusion channel and obtain the Kraus operator-sum representation ofits analytical solution. we find that the pure coherent states evolve into the new mixed thermal superposed states in thediffusion channel. Also, we investigate the statistical properties of the initial coherent states and their entropy evolutions inthe diffusion channel, and find that the entropy evolutions are only related to the decay time and without the amplitudes ofthe initial coherent states. 展开更多
关键词 entangled state representation diffusion channel coherent state entropy evolution
下载PDF
Coping with the Impact of Climate Change: A Dive into Precision Agriculture in the United States
8
作者 Oluwaseun Ibukun Kehinde Oke Olawale Oluwafemi 《Journal of Agricultural Chemistry and Environment》 2024年第2期208-222,共15页
With the continued increase in the number of people that are food insecure globally, which could be increasing because of the ongoing Ukraine-Russia war, leading to reduction in international agribusinesses, coupled w... With the continued increase in the number of people that are food insecure globally, which could be increasing because of the ongoing Ukraine-Russia war, leading to reduction in international agribusinesses, coupled with drastic climate change exacerbating the problem of food insecurity, there is a constant need to come up with innovative approaches to solve this global issue. In this article, we articulated how precision agriculture can be a tool for ensuring food security in the United States. This study aims to reiterate the significance of precision agriculture in solving global food insecurity. 展开更多
关键词 united states Food Insecurity Precision Agriculture Positioning Systems Climate Change
下载PDF
Perspectives on non-emergent neonatal intensive care unit to pediatric intensive care unit care transfers in the United States
9
作者 Phillip D Cohen Renee D Boss +3 位作者 David C Stockwell Meghan Bernier Joseph M Collaco Sapna R Kudchadkar 《World Journal of Critical Care Medicine》 2024年第4期73-80,共8页
BACKGROUND There is a substantial population of long-stay patients who non-emergently transfer directly from the neonatal intensive care unit(NICU)to the pediatric intensive care unit(PICU)without an interim discharge... BACKGROUND There is a substantial population of long-stay patients who non-emergently transfer directly from the neonatal intensive care unit(NICU)to the pediatric intensive care unit(PICU)without an interim discharge home.These infants are often medically complex and have higher mortality relative to NICU or PICUonly admissions.Given an absence of data surrounding practice patterns for nonemergent NICU to PICU transfers,we hypothesized that we would encounter a broad spectrum of current practices and a high proportion of dissatisfaction with current processes.AIM To characterize non-emergent NICU to PICU transfer practices across the United States and query PICU providers’evaluations of their effectiveness.METHODS A cross-sectional survey was drafted,piloted,and sent to one physician representative from each of 115 PICUs across the United States based on membership in the PARK-PICU research consortium and membership in the Children’s Hospital Association.The survey was administered via internet(REDCap).Analysis was performed using STATA,primarily consisting of descriptive statistics,though logistic regressions were run examining the relationship between specific transfer steps,hospital characteristics,and effectiveness of transfer.RESULTS One PICU attending from each of 81 institutions in the United States completed the survey(overall 70%response rate).Over half(52%)indicated their hospital transfers patients without using set clinical criteria,and only 33%indicated that their hospital has a standardized protocol to facilitate non-emergent transfer.Fewer than half of respondents reported that their institution’s nonemergent NICU to PICU transfer practices were effective for clinicians(47%)or patient families(38%).Respondents evaluated their centers’transfers as less effective when they lacked any transfer criteria(P=0.027)or set transfer protocols(P=0.007).Respondents overwhelmingly agreed that having set clinical criteria and standardized protocols for non-emergent transfer were important to the patient-family experience and patient safety.CONCLUSION Most hospitals lacked any clinical criteria or protocols for non-emergent NICU to PICU transfers.More positive perceptions of transfer effectiveness were found among those with set criteria and/or transfer protocols. 展开更多
关键词 TRANSFER Chronic critical illness Intensive care units Pediatric intensive care Neonatal intensive care Care transition
下载PDF
Financial Sustainability Among Higher Education Institutions in the United States
10
作者 Wanying Liang 《Journal of Contemporary Educational Research》 2023年第12期277-281,共5页
This article explores the challenges of financial sustainability faced by higher education institutions in the United States.Against a backdrop of stringent state and federal regulations coupled with a decline in fina... This article explores the challenges of financial sustainability faced by higher education institutions in the United States.Against a backdrop of stringent state and federal regulations coupled with a decline in financial support,institutions are grappling with a shifting landscape.The paper delves into the intricacies of state regulations and funding policies,highlighting their impact on educational establishments.Furthermore,strategies for financial sustainability,including student attraction and retention,are discussed.The article concludes by underscoring the duality of regulations as both challenges and essential resources,suggesting a potential shift towards greater autonomy and a reshaping of the educational landscape in response to modern challenges. 展开更多
关键词 Financial sustainability Higher education State regulations Funding policies Student retention
下载PDF
Sustained release of vascular endothelial growth factor A and basic fibroblast growth factor from nanofiber membranes reduces oxygen/glucose deprivation-induced injury to neurovascular units 被引量:3
11
作者 Yifang Wu Jun Sun +2 位作者 Qi Lin Dapeng Wang Jian Hai 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第4期887-894,共8页
Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell... Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway. 展开更多
关键词 brain ischemia brain microvascular endothelial cell nanofiber membrane neurovascular unit
下载PDF
Expert consensus on pediatric orthodontic therapies of malocclusions in children 被引量:1
12
作者 Chenchen Zhou Peipei Duan +22 位作者 Hong He Jinlin Song Min Hu Yuehua Liu Yan Liu Jie Guo Fang Jin Yang Cao Lingyong Jiang Qingsong Ye Min Zhu Beizhan Jiang Wenhua Ruan Xiao Yuan Huang Li Rui Zou Yulou Tian Li Gao Rui Shu Jianwei Chen Renkai Liu Shujuan Zou Xiaobing Li 《International Journal of Oral Science》 SCIE CAS CSCD 2024年第2期186-196,共11页
Malocclusion,identified by the World Health Organization(WHO)as one of three major oral diseases,profoundly impacts the dental-maxillofacial functions,facial esthetics,and long-term development of~260 million children... Malocclusion,identified by the World Health Organization(WHO)as one of three major oral diseases,profoundly impacts the dental-maxillofacial functions,facial esthetics,and long-term development of~260 million children in China.Beyond its physical manifestations,malocclusion also significantly influences the psycho-social well-being of these children.Timely intervention in malocclusion can foster an environment conducive to dental-maxillofacial development and substantially decrease the incidence of malocclusion or reduce the severity and complexity of malocclusion in the permanent dentition,by mitigating the negative impact of abnormal environmental influences on the growth.Early orthodontic treatment encompasses accurate identification and treatment of dental and maxillofacial morphological and functional abnormalities during various stages of dental-maxillofacial development,ranging from fetal stages to the early permanent dentition phase.From an economic and societal standpoint,the urgency for effective early orthodontic treatments for malocclusions in childhood cannot be overstated,underlining its profound practical and social importance.This consensus paper discusses the characteristics and the detrimental effects of malocclusion in children,emphasizing critical need for early treatment.It elaborates on corresponding core principles and fundamental approaches in early orthodontics,proposing comprehensive guidance for preventive and interceptive orthodontic treatment,serving as a reference for clinicians engaged in early orthodontic treatment. 展开更多
关键词 PERMANENT stated CHILDREN
下载PDF
A Study on the Transmission Dynamics of the Omicron Variant of COVID-19 Using Nonlinear Mathematical Models 被引量:1
13
作者 S.Dickson S.Padmasekaran +2 位作者 Pushpendra Kumar Kottakkaran Sooppy Nisar Hamidreza Marasi 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期2265-2287,共23页
This research examines the transmission dynamics of the Omicron variant of COVID-19 using SEIQIcRVW and SQIRV models,considering the delay in converting susceptible individuals into infected ones.The significant delay... This research examines the transmission dynamics of the Omicron variant of COVID-19 using SEIQIcRVW and SQIRV models,considering the delay in converting susceptible individuals into infected ones.The significant delays eventually resulted in the pandemic’s containment.To ensure the safety of the host population,this concept integrates quarantine and the COVID-19 vaccine.We investigate the stability of the proposed models.The fundamental reproduction number influences stability conditions.According to our findings,asymptomatic cases considerably impact the prevalence of Omicron infection in the community.The real data of the Omicron variant from Chennai,Tamil Nadu,India,is used to validate the outputs. 展开更多
关键词 Omicron local stability reproduction number steady states global stability
下载PDF
Effects of hormone replacement therapy on mood and sleep quality in menopausal women 被引量:2
14
作者 Qing Liu Zhen Huang Ping Xu 《World Journal of Psychiatry》 SCIE 2024年第7期1087-1094,共8页
BACKGROUND Hormone replacement therapy is an effective treatment strategy for the management of symptoms in naturally menopausal women.However,some patients report experiencing adverse effects.AIM To analyze the effec... BACKGROUND Hormone replacement therapy is an effective treatment strategy for the management of symptoms in naturally menopausal women.However,some patients report experiencing adverse effects.AIM To analyze the effects of hormone replacement therapy in menopausal female patients.METHODS A total of 152 menopausal female patients admitted to the Gynecology Department of the Ganzhou Maternal and Child Health Hospital between January 2021 and December 2023 were divided into the observation group(n=76,conventional treatment+hormone replacement therapy)and the control group(n=76,conventional treatment only)via random casting.The improvement observed in the following items were compared between the groups:Kupperman menopausal index(KMI),emotional state[The Positive and Negative Affect Scale(PANAS)],sleep quality[Self-Rating Scale of Sleep(SRSS)],treatment effectiveness,and treatment safety.RESULTS The modified KMI and SRSS scores of the observation group were lower than those of the control group after three rounds of treatment.The improvement in the PANAS score observed in the observation group was greater than that observed in the control group(P<0.05).The total treatment effectivity rate in the observation group was higher than that in the control group(86.84%vs 96.05%,χ2=4.121,P=0.042).The incidence rate of adverse reactions in the two groups was comparable(6.58%vs 9.21%,χ2=0.361,P=0.547).CONCLUSION Hormone replacement therapy effectively improved the clinical symptoms,actively channeled negative emotions,and improved the quality of sleep in menopausal patients,indicating its effectiveness and safety. 展开更多
关键词 Hormone replacement therapy MENOPAusE WOMEN Mood states Sleep quality Sex hormones
下载PDF
Evolution and impacts of the United States’Arctic strategy and China’s responses 被引量:1
15
作者 LIAO Junjie PAN Min 《Advances in Polar Science》 CSCD 2023年第2期144-152,共9页
On 7 October,2022,the Biden administration released an updated version of the National Strategy for the Arctic Region based on new developments in the Arctic region and global affairs.This strategy emphasizes traditio... On 7 October,2022,the Biden administration released an updated version of the National Strategy for the Arctic Region based on new developments in the Arctic region and global affairs.This strategy emphasizes traditional security issues in the Arctic,attaches great importance to climate governance in the region,and advocates for restoring American leadership through international cooperation.In view of the strong influence of the United States(U.S.)in the Arctic region,the changes of the U.S.Arctic strategy will inevitably have an impact on China’s scientific researchrights,economic interests,and governance rights in the Arctic region.To respond to the new situation brought about by the changes in the U.S.Arctic strategy,China should take the initiative to maintain positive relationships with all Arctic countries,and continue its active participation in Arctic affairs. 展开更多
关键词 the united states’Arctic strategy Arctic security Arctic governance
下载PDF
Preparation of entangledW states based on the cavity QED system
16
作者 Ke Li Jun-Long Zhao 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期290-296,共7页
We present a qubit-loss-free(QLF)fusion scheme for generating large-scale atom W states in cavity quantum electrodynamics(QED)system.Compared to the most current fusion schemes which are conditioned on the case where ... We present a qubit-loss-free(QLF)fusion scheme for generating large-scale atom W states in cavity quantum electrodynamics(QED)system.Compared to the most current fusion schemes which are conditioned on the case where one particle can be extracted from each initial W state to the fusion process,our scheme will access one or two particles from each W state.Based on the atom–cavity-field detuned interaction,three jWin+m+t states can be generated from the jWin,jWim,and jWit states with the help of two auxiliary atoms,and three jWin+m+t+q states can be generated from jWin,jWim,jWit,and a jWiq state with the help of three auxiliary atoms.Comparing the numerical simulations of the resource cost of fusing three small-size W states based on the previous schemes,our fusion scheme seems to be more efficient.This QLF fusion scheme can be generalized to the case of fusing k different or identical particle W states.Furthermore,with no qubit loss,it greatly reduces the number of fusion steps and prepares W states with larger particle numbers. 展开更多
关键词 W state detuned interaction state fusion cavity quantum electrodynamics
下载PDF
Machine-learning-assisted efficient reconstruction of the quantum states generated from the Sagnac polarization-entangled photon source
17
作者 毛梦辉 周唯 +3 位作者 李新慧 杨然 龚彦晓 祝世宁 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期50-54,共5页
Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an effic... Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source.By properly modeling the target states,a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique,and hence our method reduces the resource consumption without loss of accuracy.We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data.Explicitly,the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states.Our method could be generalized to estimate other kinds of states,as well as other quantum information tasks. 展开更多
关键词 machine learning state estimation quantum state tomography polarization-entangled photon source
下载PDF
THE LIMITING PROFILE OF SOLUTIONS FOR SEMILINEAR ELLIPTIC SYSTEMS WITH A SHRINKING SELF-FOCUSING CORE
18
作者 金可 石影 谢华飞 《Acta Mathematica Scientia》 SCIE CSCD 2024年第2期583-608,共26页
In this paper,we consider the semilinear elliptic equation systems{△u+u=αQ_(n)(x)|u|^(α-2)|v|^(β)u in R^(N),-△v+v=βQ(x)|u|^(α)|v|^(β-2)v in R^(N),where N≥3,α,β>1,α+β<2^(*),2^(*)=2N/N-2 and Q_(n) are... In this paper,we consider the semilinear elliptic equation systems{△u+u=αQ_(n)(x)|u|^(α-2)|v|^(β)u in R^(N),-△v+v=βQ(x)|u|^(α)|v|^(β-2)v in R^(N),where N≥3,α,β>1,α+β<2^(*),2^(*)=2N/N-2 and Q_(n) are bounded given functions whose self-focusing cores{x∈R^(N)|Q_(n)(x)>0} shrink to a set with finitely many points as n→∞.Motivated by the work of Fang and Wang[13],we use variational methods to study the limiting profile of ground state solutions which are concentrated at one point of the set with finitely many points,and we build the localized concentrated bound state solutions for the above equation systems. 展开更多
关键词 Schrödinger system ground states solutions bound state solutions
下载PDF
Comparative Study of the Socioeconomic Characteristics and Digital Literacy Level of Agricultural Extension Personnel in Imo and Ebonyi States, South-East, Nigeria
19
作者 Ogbonnaya Okoro Aja Cyril Chigozie Asiabaka +1 位作者 Anthony Okorie Ani Edna Chioma Matthews-Njoku 《Agricultural Sciences》 2024年第2期230-245,共16页
The study comparatively analysed the socioeconomic characteristics and digital literacy level of Agricultural Extension personnel (AEP) in Ebonyi and Imo States, South-East, Nigeria. The specific objectives were to de... The study comparatively analysed the socioeconomic characteristics and digital literacy level of Agricultural Extension personnel (AEP) in Ebonyi and Imo States, South-East, Nigeria. The specific objectives were to describe the socioeconomic characteristics of agricultural extension personnel in Ebonyi and Imo States, and to ascertain the digital literacy level of AEP in the studied states. Purposive sampling technique was used to select 312 Agricultural Extension personnel (132 from Ebonyi State Agricultural Development Program and 180 from Imo State Agricultural Development Program) for the study. Data were collected through the use of validated and structured questionnaire, and administered through the help of well-trained enumerators. Data were analysed using simple descriptive statistical tools such as percentages mean score, standard deviation and weighted mean. Findings indicated that they were more male in the both States (55.3% and 57.8%) for Ebonyi and Imo State respectively and that the average age of AEP in Ebonyi and Imo States were 44.7 years and 49.2 years respectively. It was further revealed that the majority (77.3% and 82.8%) had B.Sc./HND as their highest academic qualifications, belonged to professional organisations (62.1% and 75%), and were earning an average monthly income of N58,798 and N62,648 for Ebonyi and Imo State respectively. Also, it was revealed that their mean years of service were 12.4 years and 13.4 years for Ebonyi and Imo State respectively. Almost all of them (87.9% and 95.0%) own a smartphone, had access to the internet (80.3% and 90.0%), but do not own a laptop/ipad (82.6% and 72.8%) for Ebon-yi and Imo State respectively. Results further revealed that Agricultural extension personnel in both Ebonyi and Imo State respectively had low digital literacy level ( = 2.41 and 2.32). The study concluded that AEP in Ebonyi and Imo State respectively had similar socioeconomic characteristics and low level of digital literacy. The study recommended that the management of ADPs in both Ebonyi and Imo State should ensure the training of AEP in digital skills to enhance their digital literacy level to enable them use digital technologies in their work. 展开更多
关键词 Agricultural Extension Personnel Digital Literacy Ebonyi State Imo State Socioeconomic Characteristics
下载PDF
Hamiltonian system for the inhomogeneous plane elasticity of dodecagonal quasicrystal plates and its analytical solutions
20
作者 孙志强 侯国林 +1 位作者 乔艳芬 刘金存 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期581-590,共10页
A Hamiltonian system is derived for the plane elasticity problem of two-dimensional dodecagonal quasicrystals by introducing the simple state function. By using symplectic elasticity approach, the analytic solutions o... A Hamiltonian system is derived for the plane elasticity problem of two-dimensional dodecagonal quasicrystals by introducing the simple state function. By using symplectic elasticity approach, the analytic solutions of the phonon and phason displacements are obtained further for the quasicrystal plates. In addition, the effectiveness of the approach is verified by comparison with the data of the finite integral transformation method. 展开更多
关键词 Hamiltonian system symplectic elasticity QUASICRYSTALS analytic solution state function
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部