A generalization of Banach's lemma and its applications to perturbations of bounded linear operators

Let X be a Banach space and let P:X→X be a bounded linear operator.Using an algebraic inequality on the spectrum of P,we give a new sufficient condition that guarantees the existence of(I-P)^(-1) as a bounded linear operator on X,and a bound on its spectral radius is also obtained.This generalizes the classic Banach lemma.We apply the result to the perturbation analysis of general bounded linear operators on X with commutative perturbations.

Subgroup comparison of COVID-19 case and mortality with associated factors in Mississippi: findings from analysis of the first four months of public data

We compared subgroup differences in COVID-19 case and mortality and investigated factors associated with case and mortality rate(MR)measured at the county level in Mississippi.Findings were based on data published by the Mississippi State Department of Health between March 11 and July 16,2020.The COVID-19 case rate and case fatality rate(CFR)differed by gender and race,while MR only differed by race.Residents aged 80 years or older and those who live in a non-metro area had a higher case rate,CFR,and MR.After controlling for selected factors,researchers found that the percent of residents who are obese,low income,or with certain chronic conditions were associated with the county COVID-19 case rate,CFR,and/or MR,though some were negatively related.The findings may help the state to identify counties with higher COVID-19 case rate,CFR,and MR based on county demographics and the degree of its chronic conditions.

The role of landscape pattern analysis in understanding concepts of land cover change

Landscape ecology and landscape pattern analysis are important components of national-scale programs to identify trends in land cover change because: 1) Statistics on changes in land cover proportions are not spatial. A change matrix derived from GIS provides useful information, but it does not show the spatial form of change in the landscape. Landscape pattern metrics reveal spatial pattern. 2) A growing body of literature has shown that a change in landscape pattern might indicate important changes in ecological functions: forest connectivity and species movements, number and size of farm patches, effects on water quality. Spatial pattern is important in structuring ecological communities and in maintaining existence of competitors. Spatial pattern may be determined by disturbance and may in turn, determine how disturbances propagate through the system. 3) Sometimes landscape pattern may not significantly change, even though land cover proportions do change. Or, vice-versa, sometimes landscape pattern can significantly change, even though land cover proportions don't significantly change. 4) Landscape pattern is an inherent and important part of describing landscapes: based on the literature, one of the most important descriptive characteristics of a landscape is its texture. The objectives of this paper are to: 1) Explain the importance of the role of landscape ecology and landscape pattern analysis in land cover change studies; 2) Review the literature that specifically incorporates landscape ecology into land cover change studies; and 3) List the theoretical and technical issues involved and suggest solutions for them.

Life Stage, Gender and Movement of Blue Crabs (Callinectes sapidus) in Lake Mattamuskeet and Connecting Canals

In their ranges on east and south coasts of the Americas as well as their established invasions in the Adriatic and Baltic,blue crabs,Callinectes sapidus,inhabit estuaries,sounds and coastal oceans and are commercially and ecologically important.How crabs move in response to physical variables is important to management.We monitored life stages at canal control structures,assessed gender ratios with recreational crabbing,learned from crabbers,and studied movements of tagged crabs in a canal connecting Lake Mattamuskeet to the Pamlico sound.Juveniles enter the lake through two of 4 canals connecting to the sounds.Females migrate out through one canal.The lake standing population is about 70% male.Movements of 240 crabs in August 2012 and 102 crabs in October 2014 were quantified using RFID tags with co-located meteorological and oceanographic devices.Non-spawning females and males are nomadic.Crabs released in the canal move in response to changes in water depth and go with the flow,toward the Pamlico Sound(summer 76% and fall 78%).What crabbers describe as a fall migration appears to be concentration of crabs in warmer deeper canals and then southern movement with flow generated by strong north winds.To be effective,management strategies like migratory corridors require understanding of crab movements.

Factors associated with concussion-symptom knowledge and attitudes toward concussion care seeking in a national survey of parents of middle-school children in the US

Background:Developing appropriate concussion prevention and management paradigms in middle school(MS)settings requires understanding parents’general levels of concussion-related knowledge and attitudes.This study examined factors associated with concussion-symptom knowledge and care-seeking attitudes among parents of MS children(aged 10-15 years).Methods:A panel of 1224 randomly selected U.S.residents,aged ≥18 years and identifying as parents of MS children,completed an online questionnaire capturing parental and child characteristics.The parents’concussion-symptom knowledge was measured using 25 questions,with possible answers being“yes”,“maybe”,and“no”.Correct answers earned 2 points,“maybe”answers earned 1 point,and incorrect answers earned 0 point(range:0-50;higher scores=better knowledge).Concussion care-seeking attitudes were also collected using five 7-point scale items(range:5-35;higher scores=more positive attitudes).Multivariable ordinal logistic regression models identified predictors of higher scores.Models met proportional odds assumptions.Adjusted odds ratios(aORs)with 95%confidence intervals(95%CIs)(excluding 1.00)were deemed statistically significant.Results:Median scores were 39(interquartile range:32-44)for symptom knowledge and 32(interquartile range:28-35)for care-seeking attitude.In multivariable models,odds of better symptom knowledge were higher in women vs.men(aOR=2.28;95%CI:1.71-3.05),white/non-Hispanics vs.other racial or ethnic groups(aOR=1.88;95%CI:1.42-2.49),higher parental age(10-year-increase aOR=1.47;95%CI:1.26-1.71),and greater competitiveness(10%-scale-increase aOR=1.24;95%CI:1.13-1.36).Odds of more positive care-seeking attitudes were higher in white/non-Hispanics vs.other racial or ethnic groups(aOR=1.45;95%CI:1.06-1.99)and in older parental age(10-year-increase aOR=1.24;95%CI:1.05-1.47).Conclusion:Characteristics of middle school children’s parents(e.g.,sex,race or ethnicity,age)are associated with their concussion-symptom knowledge and care-seeking attitudes.Parents’variations in concussion knowledge and attitudes warrant tailored concussion education and prevention.

Use of sport-related concussion information sources among parents of United States middle school children

Objective:Parents may use various information sources to obtain information about sport-related concussions(SRC).This study examined SRCrelated information sources used by parents of United States middle school children(age:10-15 years).Methods:A panel of 1083 randomly selected U.S.residents,aged≥18 years and identifying as parents of middle school children,completed an online questionnaire capturing parental and child characteristics,and utilization and perceived trustworthiness of various sources of SRC-related information.Multivariable logistic regression models identified factors associated with utilizing each source.Adjusted odds ratios(OR)with 95%confidence intervals(95%CIs)excluding 1.00 were deemed significant.Results:Doctors/healthcare providers(49.9%)and other healthcare-related resources(e.g.,Centers for Disease Control and Prevention,WebMD)(37.8%)were common SRC-related information sources;64.0%of parents utilized≥1 of these sources.Both sources were considered“very”or“extremely”trustworthy for SRC-related information among parents using these sources(doctors/healthcare providers:89.8%;other healthcare-related resources:70.9%).A 10-year increase in parental age was associated with higher odds of utilizing doctors/healthcare providers(adjusted odd ratio(OR_(adjusted))=1.09,95%CI:1.02-1.16)and other healthcare-related resources(OR_(adjusted)=1.11,95%CI:1.03-1.19).The odds of utilizing doctors/healthcare providers(OR_(adjusted)=0.58,95%CI:0.40-0.84)and other healthcare-related resources(OR_(adjusted)=0.64,95%CI:0.44-0.93)were lower among parents whose middle school children had concussion histories versus the parents of children who did not have concussion histories.Conclusion:One-third of parents did not report using doctors/healthcare providers or other healthcare-related resources for SRC-related information.Factors associated with underutilization of these sources may be targets for future intervention.Continuing education for healthcare providers and educational opportunities for parents should highlight accurate and up-to-date SRC-related information.

Toward development of the 4Dvar data assimilation system in the Bering Sea:reconstruction of the mean dynamic ocean topography

The Bering Sea circulation is derived as a variational inverse of hydrographic profiles（ temperature and salinity） , atmospheric climatologies and historical observation of ocean curents. The important result of this study is estimate of the mean climatological sea surface height （SSH） that can be used as a reference for satellite altimetry sea level anomaly data in the Bering Sea region. Numerical experiments reveal that, when combined with satellite altimetry, the obtained reference SSH effectively constrains a realistic reconstruction of the Amukta Pass circulation.

Trends of Abundance of Salton Sea Fish: A Reversible Collapse or a Permanent Condition?

The Salton Sea is a closed-basin, 980 km2 salt lake in the Sonoran Desert of southern California. Three marine species, bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), and sargo (Anisotremus davidsoni), established from introductions of over 34 species beginning in 1929. During the late 1960s and early 1970s, a hybrid tilapia (Oreochromis mossambicus × O. urolepis hornorum) invaded the Salton Sea and became dominant by number and weight. Recent surveys show a precipitous decline of all four species above starting sometime between 2001 and 2002. Declines were more evident in nearshore than in estuarine habitats. Corvina has probably declined the soonest, followed by Gulf croaker. Tilapia declines were followed by more recent increases in population numbers. The tilapia rebound observed are probably only sustainable if a curb in Salton Sea salinity levels is realized. The marine species will likely need restocking to reach historic levels, if the salinity of the lake is managed at 40 g•L–1 or below. Restoration alternatives for the Salton Sea must take into consideration estuarine areas as essential fish habitats and fish refuge against high salinities.

Factors and expectations influencing concussion disclosure within NCAA DivisionⅠathletes:A mixed methodological approach

Background:Participation in sports is associated with many benefits to all aspects of health;however,it also comes with the risk of injury,particularly concussions.Self-disclosure and care seeking following a concussion are especially important because of the lack of outwardly visible signs and/or symptoms.Although recent research has explored factors affecting concussion disclosure,use of isolated methodologies limits the ability to contextualize how disclosure or nondisclosure occurs.Therefore,the purpose of this study was to describe the factors and expectations of National Collegiate Athletic Association(NCAA)athletes that may influence concussion disclosure.Methods:This mixed-methods convergent parallel research study included 25 NCAA Division I athletes representing 13 sports,all of whom completed a concussion-education session with pre-/post-test surveys and a semistructured interview.Eligible athletes were at least 18 years old and on an NCAA roster.The surveys focused on previous concussion-related disclosure behaviors,knowledge,attitudes,beliefs,norms,and intentions about disclosing concussion.Interviews focused on the athletes’experiences related to concussion disclosure.Survey data were analyzed using descriptive statistics and Mann-Whitney U tests.Interviews were analyzed using a Consensual Qualitative Research tradition.Results:Participants had good concussion knowledge(median=46.0),positive attitudes(median=38.0),strong beliefs(median=13.0),and strong intentions to disclose concussion symptoms(median=7.0).None of the constructs differed by participants’gender.Although quantitative findings were mostly positive,interview data highlighted factors that may explain why some participants are successful in disclosing concussions and why others may find disclosure difficult.Educational efforts,sport culture,and medical professional presence were the primary facilitators discussed by participants.Stigma,pressure,and a lack of team support were perceived as disclosure barriers.Conclusion:The context in which concussion disclosure occurs or does not occur is vital to the success of educational interventions.Interventions must prioritize stakeholder-and team-based perspectives on concussion to establish a network supportive to disclosure.

红胁蓝尾鸲(Tarsiger cyanurus)在中国东北部帽儿山地区的迁徙中途停歇生态(英文)

中国迁徙鸣禽类的保护面对着与世界其他地区如欧洲和北美洲鸟类保护相似的挑战。迁徙鸣禽类具有复杂生活周期和很大的空间关联。迁徙过程中发生的事件对迁徙鸣禽类种群动态具有决定作用。对于鸣禽类迁徙中途停歇期的生态,比如停歇期的长短,能量的积累,生境的利用等,了解还非常有限。在中国东北部的一个鸟类迁徙停歇地对红胁蓝尾鸲(Tarsigercyanurus)的中途停歇生态包括迁徙时间、停歇时间、能量状态和性比进行了研究。2002年秋和2003年春分别捕获了1751只和684只红胁蓝尾鸲。红胁蓝尾鸲的体重在秋季迁徙时要比在春季迁徙时重。春季雌性红胁蓝尾鸲停歇时的能量状态指数最低;而秋季的红胁蓝尾鸲比春季的红胁蓝尾鸲停歇时间更长。无论季节和性别,红胁蓝尾鸲的能量状态指数和第1次捕获的时间早晚成正相关,间接证明红胁蓝尾鸲在停歇期间能够比较快地积累能量。秋季雄性红胁蓝尾鸲日体重净增率最大。估测秋季停歇期的每日能量净增能维持红胁蓝尾鸲雌性0.6h和雄性3.1h的飞行。红胁蓝尾鸲的中途停歇生态与北美和欧洲一些迁徙鸣禽类很相似。比如,春季迁徙过境的时间和脂肪积累的变化与自然选择对雄性的要求:当食物和气候适宜时尽快到达繁殖地的假设是一致的。对迁徙中途的停歇生态研究有利于更好地了解鸟类的迁徙行为和更有效地保护迁徙鸣禽类。

长距离迁徙鸟类对应于能量积累状态的取食行为调整

迁徙鸟类能够预计到迁徙过程中对能量需求的增加和迁徙途中获得能量的不确定性。最佳迁徙理论指出 :迁徙停留期的一系列决策受到体内能量状态、取食机会和迁徙时间的影响。利用刚完成春季跨越墨西哥湾迁徙的鸫类 ,我们研究了取食行为、体内能量状态和能量积累速度的相互关系。我们用雾网捕获了停留的鸫 ,然后给每只鸟进行了环志和称重 ,并估测了表皮下积累的脂肪。为了检测体内能量积累大小对取食行为的影响 ,我们把在野外观察到的鸟分成肥、瘦两组。当一天里被捕获鸟的平均体重低于相关种的瘦体重时 ,这一天被观察到的取食鸟被归到瘦组 ,反之就属于肥组。我们同时对一部分鸟用有色环进行了标记 ,以便能在野外观察到它们时能准确地知道每一只鸟的初始能量积累状态。在春天完成跨越墨西哥湾迁徙以后的鸫大约有 5 0 %在到达停留地时就已经消耗了所有的表皮下脂肪。与肥组鸟相比 ,瘦组的个体在停留期扩展了取食方法和取食基底 ,增加了取食速度。与此相关的是 ,瘦鸟表现出体重积累更多、速度更快。我们的数据表明迁徙鸟在到达迁徙中途停留地时的能量状态会影响到它们停留期间的取食行为和继续迁徙时的生理机能 。

A local refinement purely meshless scheme for time fractional nonlinear Schrodinger equation in irregular geometry region

A local refinement hybrid scheme(LRCSPH-FDM)is proposed to solve the two-dimensional(2D)time fractional nonlinear Schrodinger equation(TF-NLSE)in regularly or irregularly shaped domains,and extends the scheme to predict the quantum mechanical properties governed by the time fractional Gross-Pitaevskii equation(TF-GPE)with the rotating Bose-Einstein condensate.It is the first application of the purely meshless method to the TF-NLSE to the author’s knowledge.The proposed LRCSPH-FDM(which is based on a local refinement corrected SPH method combined with FDM)is derived by using the finite difference scheme(FDM)to discretize the Caputo TF term,followed by using a corrected smoothed particle hydrodynamics(CSPH)scheme continuously without using the kernel derivative to approximate the spatial derivatives.Meanwhile,the local refinement technique is adopted to reduce the numerical error.In numerical simulations,the complex irregular geometry is considered to show the flexibility of the purely meshless particle method and its advantages over the grid-based method.The numerical convergence rate and merits of the proposed LRCSPH-FDM are illustrated by solving several 1D/2D(where 1D stands for one-dimensional)analytical TF-NLSEs in a rectangular region(with regular or irregular particle distribution)or in a region with irregular geometry.The proposed method is then used to predict the complex nonlinear dynamic characters of 2D TF-NLSE/TF-GPE in a complex irregular domain,and the results from the posed method are compared with those from the FDM.All the numerical results show that the present method has a good accuracy and flexible application capacity for the TF-NLSE/GPE in regions of a complex shape.

从购物动机到商店选择:中国西北消费者的购物行为探索(英文)

虽然中国已经成为世界上最大的消费者市场,但是有关中国消费者的购物行为研究还没有广泛开展,特别是针对中国内地的购物人群而言。本研究探索的是中国西北消费者的购物经历。深度采访显示,那些被访者更多地展现出一种消费者角色,这种角色能够同时满足个人和社会地位需求的购物特征。除此之外,在选择零售商店(购物)时,商品、商店和服务标准也是重要的影响因素。本文为研究中国消费者的商店购买行为提供了参考文献资料,同时也为零售商拓展中国西北市场提供了非常有价值的观点。

A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai,China

Recent sediments from Lake Chenghai, China, were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon （TOC）, total nitrogen （TN）, total phosphorus （TP）, organic phosphorus （Po）, inorganic phosphorus （Pi） and organic carbon and nitrogen stable isotopes （~13Corg and 615N） in a 137Cs-dated sediment core. The results indicated that the sedimentary record covers the last 60 years, during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading. Prior to the late 1980s, the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable. Since the late 1980s, increasing TOC, TN and TP concentrations together with the change of 613Corg and 615N suggested anthropogenic perturbations in nutrient loading and lake productivity. Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients. The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s, and domestic wastewater discharged from Yongsheng County since 1993.

Metal concentrations of insects associated with the South African Ni hyperaccumulator Berkheya coddii （Asteraceae）

The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body metal concentrations （Co, Cr, Cu, Mg, Mn, Ni, Pb, Zn）. We also documented the concentrations of these metals in leaves, stems and inflorescences, finding extremely elevated levels of Ni （4 700-16 000μg/g） and high values （5-34μg/g） for Co, Cr, and Pb. Of 26 insect morphotypes collected from B. coddii, seven heteropterans, one coleopteran, and one orthopteran contained relatively high concentrations of Ni （〉 500μg/g）. The large number of high-Ni heteropterans adds to discoveries of others （from California USA and New Caledonia） and suggests that members of this insect order may be particularly Ni tolerant. Nymphs of the orthopteran （Stenoscepa） contained 3 500 μg Ni/g, the greatest Ni concentration yet reported for an insect. We also found two beetles with elevated levels of Mg （〉 2 800 μg/g）, one beetle with elevated Cu （〉 70 μg/g） and one heteropteran with an elevated level of Mn （〉 200 μg/g）. Our results show that insects feeding on a Ni hyperaccumulator can mobilize Ni into food webs, although we found no evidence of Ni biomagnification in either herbivore or carnivore insect taxa. We also conclude that some insects associated with hyperaccumulators can contain Ni levels that are high enough to be toxic to vertebrates.

Host-herbivore studies of Stenoscepa sp. （Orthoptera：Pyrgomorphidae）, a high-Ni herbivore of the South African Ni hyperaccumulator Berkheya coddii （Asteraceae）

Nymphs of Stenoscepa sp. feed on leaves of the Ni hyperaccumulator Berkheya coddii at serpentine sites in Mpumalanga Province, South Africa. These sites contain Ni hyperaccumulators, Ni accumulators, and plants with Ni concentrations in the normal range. We conducted studies to： （i） determine the whole-body metal concentration of nymphs （including those starved to empty their guts）; （ii） compare Stenoscepa sp. nymphs against other grasshoppers in the same habitat for whole-body metal concentrations; and （iii）compare the suitability of Ni hyperaccumulator and Ni accumulator plants as food sources for Stenoscepa sp. and other grasshoppers. Stenoscepa nymphs had extremely high whole-body Ni concentrations （3 500μg Ni/g）. This was partly due to food in the gut, as starved insects contained less Ni （950 pg Ni/g）. Stenoscepa nymphs survived significantly better than other grasshoppers collected from either a serpentine or a non-serpentine site when offered high-Ni plants as food. In a host preference test among four Berkheya species （two Ni hyperaccumulators and two Ni accumulators）, Stenoscepa sp, preferred leaves of the Ni hyperaccumulator species. A preference experiment using leaves of three Senecio species （of which one species, Senecio coronatus, was represented by both a Ni hyperaccumulator and a Ni accumulator population） showed that Stenoscepa sp. preferred Ni accumulator Senecio coronatus leaves to all other choices. We conclude that Stenoscepa sp. is extremely Ni-tolerant. Stenoscepa sp. nymphs prefer leaves of hyperaccumulator Berkheya species, but elevated Ni concentration alone does not determine their food preference. We suggest that the extremely high whole-body Ni concentration of Stenoscepa nymphs may affect food web relationships in these serpentine communities.

Commuting Solutions of a Quadratic Matrix Equation for Nilpotent Matrices

我们与给定的 nilpotent 矩阵 A 解决二次的矩阵方程 AXA = XAX，到发现所有变换答案。我们首先提供一个关键词根，并且认为 A 有的特殊情况是一仅仅乔丹块为一般的格激发这个想法。我们的主要结果与一个任意的 nilpotent 矩阵给方程的所有变换答案的结构。

Improving construction work zone safety using technology:A systematic review of applicable technologies

Once considered conventional,the construction industry is gradually increasing its reliance on innovations such as the application of technologies in safety management.Given the growing literature on technology applications in safety management and the varying opinions on the utility of applied technologies,a systematic review that streamlines findings from past studies is indispensable to construction stakeholders.Although a number of review studies are available in the building construction sector,the level of fragmentation and uniqueness within the construction industry necessitates a review study specifically targeting the heavy civil sector.In response,the present study applies a three-step approach to identify and review articles pertinent to the safety of highway construction work zones.The factors considered include the number of publications per year,publication locations,and technology types.In addition,the present study proposes to broadly group work zone safety technologies(WZSTs)into three categories based on their primary purpose:speed reduction systems,intrusion prevention and warning systems,and human-machine-interaction detection systems.Key findings include WZST research trends,application of smart work zone systems,and the potential relationship between WZSTs and fatalities.The paper ends with the identification of six additional research areas aimed at deepening the understanding of technology’s role in highway safety management.The trend analysis and an in-depth discussion of each technology category alongside the identified research gaps will provide a substantial informative body of knowledge that both benefits current practitioners and directs researchers towards potential future studies.