THE PERSISTENCE OF SOLUTIONS IN A NONLOCAL PREDATOR-PREY SYSTEM WITH A SHIFTING HABITAT

In this paper,we mainly study the propagation properties of a nonlocal dispersal predator-prey system in a shifting environment.It is known that Choi et al.[J Differ Equ,2021,302:807-853]studied the persistence or extinction of the prey and of the predator separately in various moving frames.In particular,they achieved a complete picture in the local diffusion case.However,the question of the persistence of the prey and of the predator in some intermediate moving frames in the nonlocal diffusion case was left open in Choi et al.'s paper.By using some a prior estimates,the Arzelà-Ascoli theorem and a diagonal extraction process,we can extend and improve the main results of Choi et al.to achieve a complete picture in the nonlocal diffusion case.

The Persistence and Zonal Scale of Atmospheric Dipolar Modes

This study investigates the relationship between the persistence and the zonal scale of atmospheric dipolar modes(DMs). Results from the daily data of ERA5 and the long-term output of an idealized atmospheric model show that the atmospheric DMs with a broader(narrower) zonal scale dipolar structure possess a longer(shorter) persistence. A detailed vorticity budget analysis indicates that the persistence of a hemispheric-scale DM(1/1 DM) and a regional or sectoral DM(1/8 DM) in the model both largely rely on the persistence of the nonlinear eddy forcing. Linear terms can indirectly reduce the persistence of the anomalous nonlinear eddy forcing in a 1/8 DM by modifying the baroclinicity via the arousal of anomalous vertical motions. Therefore, the atmospheric DMs with a broader(narrower) zonal scale possess a longer(shorter) persistence because the effects of the linear terms are less(more) pronounced when the atmospheric DMs have better(worse) zonal symmetry. Further analyses show that the positive eddy feedback effect is weak or even absent in a 1/8DM and the high-frequency eddy forcing acts more like a concomitant phenomenon rather than a leading driving factor for a 1/8 DM. Thus, the hemispheric-scale DM and the regional or sectoral DMs are different, not only in their persistence but also in their dynamics.

Mechanisms to explain soil liquefaction triggering,development,and persistence during an earthquake

Mechanisms have been proposed to explain the triggering,development,and persistence of soil liquefaction.The mechanism explaining the horizontal failure plane(triggering)and its depth below the phreatic surface is governed by the flux properties and effective stress at that plane.At the failure plane,the pore water pressure was higher than the effective stress,and the volume change was the highest.The pore water pressure is a function of the soil profile features(particularly the phreatic zone width)and bedrock motion(horizontal acceleration).The volume change at the failure plane is a function of the intrinsic permeability of the soil and bedrock displacement.The failure plane was predicted to occur during the oscillation with the highest amplitude,disregarding further bedrock motion,which was consistent with low seismic energy densities.Two mechanisms were proposed to explain the persistence of soil liquefaction.The first is the existence of low-permeability layers in the depth range in which the failure planes are predicted to occur.The other allows for the persistence and development of soil liquefaction;it is consistent with homogeneous soils and requires water inflow from bedrock water springs.The latter explains many of the features of soil liquefaction observed during earthquakes,namely,surficial effects,“instant”liquefaction,and the occurrence of short-and long-term changes in the level of the phreatic surfaces.This model(hypothesis),the relationship between the flux characteristics and loss of soil shear strength,provides self-consistent constraints on the depth below the phreatic surfaces where the failure planes are observed(expected to occur).It requires further experimental and observational evidence.Similar reasoning can be used to explain other saturated soil phenomena.

The Transport and Persistence of Escherichia coli in Leachate from Poultry Litter Amended Soils

Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 103 to 3.044 × 103 CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 106 CFU for Decatur silty loam and 6.3 × 106 CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.

石家庄市R&D经费投入现状分析与对策研究

R&D经费投入强度,是国际上通用的衡量一个国家或者地区科技投入强度的重要指标,成为评价其科技实力、核心竞争力和创新程度的重要标准。本文在对石家庄市研发投入开展调研的基础上,对R&D经费投入开展总体分析、结构分析、横纵向比较分析,找出存在的问题,提出加大政府对科研活动的支持、大力发展新兴产业、重视研发投入统计等对策与建议。

政府R&D补贴的技术创新效应分析--基于2009-2021年中国的经验数据

政府R&D补贴既可以通过提供公共服务的方式直接作用于技术创新,也可以通过对社会资本的引导作用间接影响技术创新,其总效应取决于两种影响的方向与大小。基于2009—2021年中国的经验数据,建立了由技术创新方程和引致方程共同组成的动态模型,对政府R&D补贴的技术创新效应进行了实证分析。结果发现:持续增加的政府R&D补贴带来了国内专利授权数量的稳定增加,技术创新效应较为显著;政府R&D补贴不仅对技术创新产生了积极的直接影响,也通过引导社会资本投资于研发领域而对技术创新产生了积极的间接影响;政府R&D补贴的技术创新效应存在区域差异,中东部地区为正,而西部地区为负。提高资金使用效率、积极引导社会资本投资技术研发、努力改善欠发达地区的研发环境,无疑是提高政府R&D补贴技术创新效应的必要选择。

云南省R&D经费投入结构动态研究

为研究云南省“十二五”以来R&D经费投入结构变化,分析R&D经费投入现状,并与全国,东、中、西部地区及临近省份进行了对比;从资金来源和资金配置视角,运用Cobb-Douglas效用函数及其修正模型对R&D经费投入结构展开动态分析。结果表明:云南省R&D经费投入结构不尽合理,资金来源中政府资金占比较低且呈下降趋势,资金配置中基础研究和应用研究投入不足,与最优结构偏离程度较大。针对存在的问题,提出持续加大政府R&D经费投入力度、围绕产业链提升基础研究和应用研究比重的建议。

R&D资本化背景下我国TFP增长率再测算

研究与试验发展(R&D)资本对经济增长和科技创新作用日益凸显,但对于R&D资本的核算亟待完善。本文基于SNA2008和CSNA2016框架,将R&D支出作为资本形成,对我国各省份物质资本存量和R&D资本存量进行规范化测算,使用随机前沿分析法重新估算1991—2019年间的全要素生产率(TFP)增长率。研究发现:第一,我国R&D资本存量规模呈总体递增和地区聚集趋势;第二,1991—2019年间,我国广义TFP增长率年平均增幅为2.10%,对经济增长存在正向作用;第三,将TFP增长率分解为技术进步、前沿技术效率和规模效应,发现技术进步对TFP增长率的贡献最大,是推动我国TFP增长的主导力量,但却呈现逐年递减的趋势;第四,随着我国对R&D投入的不断增加与重视,R&D对我国广义TFP增长率的贡献呈现递增的趋势,R&D的贡献逐渐成为推动我国科技进步的主要力量。

政府R&D资助对OFDI逆向绿色创新的影响机制研究

应用中国分省区层面数据并采用面板门槛模型,实证考察了政府R&D资助影响OFDI逆向绿色创新的动态效应。研究发现,OFDI对国内绿色创新产生了显著的驱动效应,但这种影响呈现出明显的先负后正的“U”型动态演化特征;政府R&D资助会正向调节OFDI逆向绿色创新溢出,且存在最适宜于OFDI逆向绿色创新的政府R&D资助区间(0.366,0.428],过高或过低强度的政府R&D资助均会在一定程度上造成OFDI逆向绿色创新的红利损失;政府R&D资助调节下OFDI对绿色创新的动态影响具有显著时空异质性,即在时空维度上存在“激励效应”与“挤出效应”交替演化的鲜明特征。

Multiframe-integrated, in-sensor computing using persistent photoconductivity

The utilization of processing capabilities within the detector holds significant promise in addressing energy consumption and latency challenges. Especially in the context of dynamic motion recognition tasks, where substantial data transfers are necessitated by the generation of extensive information and the need for frame-by-frame analysis. Herein, we present a novel approach for dynamic motion recognition, leveraging a spatial-temporal in-sensor computing system rooted in multiframe integration by employing photodetector. Our approach introduced a retinomorphic MoS_(2) photodetector device for motion detection and analysis. The device enables the generation of informative final states, nonlinearly embedding both past and present frames. Subsequent multiply-accumulate (MAC) calculations are efficiently performed as the classifier. When evaluating our devices for target detection and direction classification, we achieved an impressive recognition accuracy of 93.5%. By eliminating the need for frame-by-frame analysis, our system not only achieves high precision but also facilitates energy-efficient in-sensor computing.

The Role of Underlying Boundary Forcing in Shaping the Recent Decadal Change of Persistent Anomalous Activity over the Ural Mountains

Observational analyses demonstrate that the Ural persistent positive height anomaly event(PAE) experienced a decadal increase around the year 2000, exhibiting a southward displacement afterward. These decadal variations are related to a large-scale circulation shift over the Eurasian Continent. The effects of underlying sea ice and sea surface temperature(SST) anomalies on the Ural PAE and the related atmospheric circulation were explored by Atmospheric Model Intercomparison Project(AMIP) experiments from the Coupled Model Intercomparison Project Phase 6 and by sensitivity experiments using the Atmospheric General Circulation Model(AGCM). The AMIP experiment results suggest that the underlying sea ice and SST anomalies play important roles. The individual contributions of sea ice loss in the Barents-Kara Seas and the SST anomalies linked to the phase transition of the Pacific Decadal Oscillation(PDO) and Atlantic Multidecadal Oscillation(AMO) are further investigated by AGCM sensitivity experiments isolating the respective forcings.The sea ice decline in Barents-Kara Seas triggers an atmospheric wave train over the Eurasian mid-to-high latitudes with positive anomalies over the Urals, favoring the occurrence of Ural PAEs. The shift in the PDO to its negative phase triggers a wave train propagating downstream from the North Pacific. One positive anomaly lobe of the wave train is located over the Ural Mountains and increases the PAE there. The negative-to-positive transition of the AMO phase since the late-1990s causes positive 500-h Pa height anomalies south of the Ural Mountains, which promote a southward shift of Ural PAE.

企业R&D支出费用化资本化与会计盈余管理行为选择研究——基于中国部分上市公司的经验数据

本文基于中国部分上市公司的数据,选取R&D支出全部费用化、全部资本化、部分资本化3个虚拟变量及R&D支出费用化金额、资本化金额用以表征R&D支出披露形式,研究上市公司R&D支出会计政策选择是否与盈余管理程度相关,进而检验R&D支出会计处理盈余管理路径,即检验R&D支出费用化、资本化的确定依据是否受其他非准则因素影响。研究结果显示,有条件资本化会计处理可能成为管理层盈余管理手段,包括应计盈余管理和真实盈余管理。在确定R&D支出费用化金额、资本化金额及R&D支出费用化强度上,管理层除了依据会计准则,还要依据当期利润情况、所得税负、利润质量、审计成本、利润平滑和公司独立性的影响。

粤港澳大湾区企业R&D活动特征研究

基于上市公司数据,对粤港澳大湾区企业R&D活动的行业、规模、经济类型以及研发效益的时滞特征进行研究。发现的典型事实有:(1)企业R&D活动具有明显的行业特征,高强度的研发企业主要聚集于信息通信技术(ICT)、医药制造、仪器仪表和设备制造等高新技术行业;(2)企业研发活动与企业规模有关,大型企业的研发规模大,但是小型企业研发强度最高,大型企业最低;(3)经济类型不同企业的研发投入强度没有显著差异,长期以来认为“国有企业研发强度和效率不如民营企业”的断言不符合实际;(4)企业研发强度与自身经营状况联系密切,盈利能力越强的企业R&D投入强度通常越高,盈利不佳的企业通常难以进行高强度的研发;(5)企业R&D研发效益的产生往往具有相当长的时滞,ICT行业中软件服务业研发效益的产生通常需要两年的滞后期,硬件设备制造业通常在五年以上。为促使企业持续加大R&D投入,尽快实现将粤港澳大湾区建成全球科技创新高地和新兴产业重要策源地的目标,一方面要大力培育企业经营者的企业家精神,另一方面应进一步改革税制,降低制造业增值税税率,增强企业的盈利能力和持续加大研发投入强度的能力。

基于PS/DSInSAR的云南德钦县滑坡变形监测

滑坡是我国最严重的地质灾害之一。针对常规MTInSAR技术在开展滑坡形变监测时面临的监测点密度不足、监测精度受限及滑坡解译受阻的问题,提出一种有效融合PS及DS点的PS/DSInSAR技术。首先,开展HTCI同质像素识别及相干性n次幂加权的相位优化处理,并筛选DS候选点;然后,将其与振幅离差获取的PS点进行融合并筛选高质量监测点,通过对监测点的相位解译提取滑坡形变信息。以云南省德钦县为研究区开展相关滑坡监测分析。实验结果表明,PS/DSInSAR技术获取的监测点密度较常规的StaMPS-SBAS技术提升了约14倍,可以更精准地识别滑坡边界及开展时序演化分析,且分析表明,研究区滑坡与季节性降雨具有显著的相关性。

2021年副省级城市R&D经费投入分析

2017—2021年,副省级城市的R&D经费投入都保持持续增长的态势。深圳的R&D经费投入在副省级城市中一直处于遥遥领先的地位,西安由于科研院所和高校众多,2017年R&D经费投入总量在副省级城市中排名第四,2021年排名第七,被资源禀赋相似的南京、成都、武汉等城市超越。西安由于GDP总量不高,R&D经费投入强度一直保持在5%左右,2020年被深圳反超。基于数据的可获得性,本文从2021年副省级城市的R&D经费投入总量、R&D经费投入强度等方面进行解读和分析,并结合分析结果提出相关建议,以供参考。

Comparative Study of Acute Coronary Syndrome with Persistent ST-Segment Elevation (STEMI) between Diabetics and Non-Diabetics in Dakar, Senegal

Introduction: This study aimed to compare the frequency of diabetic and non-diabetic patients admitted for ST-elevation myocardial infarction (STEMI), assess their epidemiological, clinical, and paraclinical profiles, and evaluate their therapeutic strategies and outcomes. Methodology: A descriptive, analytical, comparative study with prospective and retrospective data collection was conducted from April 1, 2020, to March 31, 2021. Diabetic and non-diabetic patients with STEMI admitted to a cardiology department were included. STEMI diagnosis was based on clinical and electrocardiographic criteria showing persistent ST-segment elevation in at least two leads. All patients included in the study signed a written, informed consent form. Data analysis was performed using SPSS, with a p-value ≤ 0.05 considered statistically significant. Results: STEMI prevalence was 15.27%, with 37.11% of patients being diabetic and 62.89% non-diabetic. Diabetic patients had a mean age of 59.2 ± 10.9 years, while non-diabetics averaged 58 ± 13.4 years. Diabetics were predominantly female (72.2%), whereas non-diabetics were mainly male (83.6%). Smoking was less frequent among diabetics (25% vs. 47.54%), but hypertension, obesity, and sedentary lifestyle were more common. Diabetics had an average of 3.5 ± 1.1 risk factors compared to 2.6 ± 1.2 in non-diabetics. Admission delay was longer for diabetics (34.8 ± 51.6 hours vs. 23.3 ± 52.3 hours). Chest pain was the main symptom in both groups. Electrocardiograms showed that anterior and inferior infarctions were most frequent. Triple vessel disease and severe complications, such as cardiogenic shock, were more common in diabetics, who also had higher mortality (5.56% vs. 3.28%). Conclusion: Diabetic STEMI patients represent a high-risk group with distinct clinical features, longer admission delays, and a greater accumulation of cardiovascular risk factors, emphasizing the need for targeted interventions.

Yield of alarm features in predicting significant endoscopic findings among hospitalized patients with dyspepsia

BACKGROUND Dyspepsia is a very prevalent upper gastrointestinal tract symptoms complex.Some of these symptoms might arise from serious underlying diseases,so the promotion of evidence-based guidelines could potentially better align evaluation and treatment.AIM To determine the value of alarm features as a predictive factor for significant endoscopic findings(SEFs)among hospitalized patients presenting with dyspepsia.METHODS We conducted a retrospective case-control study including information about 6208 endoscopic procedures performed for hospitalized patients.Patients were divided into two groups,with and without SEFs,and compared to elucidate the ability of the different alarm features to predict SEFs.RESULTS During the study,605 patients fulfilled the inclusion criteria.When the demographics and clinical characteristics of the two groups were compared,tachycardia(P<0.05),normocytic anemia,(P<0.05),leukocytosis(P<0.05),and hypoalbuminemia(P<0.05)documented on admission prior to endoscopy were strong predictors of SEFs.Among the alarm features,upper gastrointestinal bleeding,persistent vomiting,odynophagia[odds ratio(OR)=3.81,P<0.05;OR=1.75,P=0.03;and OR=7.81,P=0.07,respectively]were associated with SEFs.Unexplained weight loss was strongly associated with malignancy as an endoscopic finding(OR=2.05;P<0.05).In addition,long-term use of anti-aggregate medications other than aspirin(P<0.05)was correlated to SEFs.CONCLUSION Novel predictors of SEFs were elucidated in this study.These parameters could be used as an adjunctive in decision making regarding performing upper endoscopy in hospitalized patients with dyspepsia.

Herpes Simplex Virus Encephalitis Complicated by Acute Ischemic Stroke

Introduction: Herpes simplex virus is the most common etiology for life-threatening sporadic encephalitis worldwide. Antiviral therapy with acyclovir has been shown to reduce mortality and should be started promptly in patients with clinically suspected viral encephalitis before serological confirmation of the diagnosis. Despite antiviral treatment, it is associated with significant mortality and a wide range of neurologic sequelae or neuropsychiatric disorders. Clinical presentation includes fever, headache, altered mental status, and focal or generalized seizures. In some cases, it can present with focal neurological deficits, such as an acute stroke. The aim of this study is to identify rare complications of HSVE. Presentation: We present a case of a 71-year-old female patient with herpes virus encephalitis and an ischemic cerebral accident. The findings of CT scan of the brain revealed an extensive right temporal hypodensity. CSF findings include an elevated protein level, normal glucose level and pleocytosis with lymphocyte predominance. The lumbar tap confirmed the presence of herpes simplex virus type 1 with polymerase chain reaction (PCR) in the CSF. Neurological manifestations include focal neurological deficit with left-sided hemiparesis and coma. After 40 days of complex therapy, an improvement in the mental state was observed. Conclusion: There are varying degrees of neurologic sequelae among survivors in children and adults despite the antiviral treatment. Herpes simplex encephalitis has significant morbidity and high mortality due to the lack of prophylactic treatment and preventable strategies.

A Comprehensive Survey on Advanced Persistent Threat (APT) Detection Techniques

The increase in number of people using the Internet leads to increased cyberattack opportunities.Advanced Persistent Threats,or APTs,are among the most dangerous targeted cyberattacks.APT attacks utilize various advanced tools and techniques for attacking targets with specific goals.Even countries with advanced technologies,like the US,Russia,the UK,and India,are susceptible to this targeted attack.APT is a sophisticated attack that involves multiple stages and specific strategies.Besides,TTP(Tools,Techniques,and Procedures)involved in the APT attack are commonly new and developed by an attacker to evade the security system.However,APTs are generally implemented in multiple stages.If one of the stages is detected,we may apply a defense mechanism for subsequent stages,leading to the entire APT attack failure.The detection at the early stage of APT and the prediction of the next step in the APT kill chain are ongoing challenges.This survey paper will provide knowledge about APT attacks and their essential steps.This follows the case study of known APT attacks,which will give clear information about the APT attack process—in later sections,highlighting the various detection methods defined by different researchers along with the limitations of the work.Data used in this article comes from the various annual reports published by security experts and blogs and information released by the enterprise networks targeted by the attack.

Characteristics and Mechanisms of Persistent Wet–Cold Events with Different Cold-air Paths in South China

We investigate the characteristics and mechanisms of persistent wet–cold events(PWCEs)with different types of coldair paths.Results show that the cumulative single-station frequency of the PWCEs in the western part of South China is higher than that in the eastern part.The pattern of single-station frequency of the PWCEs are“Yangtze River(YR)uniform”and“east–west inverse”.The YR uniform pattern is the dominant mode,so we focus on this pattern.The cold-air paths for PWCEs of the YR uniform pattern are divided into three types—namely,the west,northwest and north types—among which the west type accounts for the largest proportion.The differences in atmospheric circulation of the PWCEs under the three types of paths are obvious.The thermal inversion layer in the lower troposphere is favorable for precipitation during the PWCEs.The positive water vapor budget for the three types of PWCEs mainly appears at the southern boundary.