Spatial variation in soil inorganic nitrogen across an arid urban ecosystem

We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO₃-N and NH₄-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO₃-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH₄-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO₃-N and NH₄-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO₃-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.     

科学家的精神动力与爱国主义

一、科学家献身国防的精神动力爱因斯坦曾在普朗克六十寿诞的庆祝会上指出有三种科学探索的动机:“在科学的庙堂里有许多房舍,住在里面的人真是各式各样,而引导他们到那里去的动机实在也各不相同。有许多人所以爱好科学,是因为科学给他们以超乎常人的智力上的快感,科学是他们自己的特殊娱乐,他们在这种娱乐中寻求生动活泼的经验和雄心壮志的满足;在这座庙堂里,另外还有许多人所以把他们的脑力产物奉献在祭台上,为的是纯粹功利的目的……对于这些人来说,只要有机会,人类活动的任何领域他们都会去干;他们究竟成为工程师,官吏,商人,还是科学家,…     

汉藏美术比较研究

本文主要比较分析了汉藏两民族美术创作诸方面的相同之处和不同之处。作者认为，梳理两者的长与短是为了二者互相学习，互相交流，取长补短，使各自的美术创作获得更大的发展。     

略论中国艺术的审美取向

悠久灿烂的华夏文明 ,孕育了中国艺术鲜明独特的审美取向 ,概括起来主要有 :自然的旨趣 ;简淡的追求 ;飘逸的气质 ;空灵的境界     

王夫之对义、利的层次性及相对性的分析

义利观问题是中国伦理思想史的核心问题之一，历代思想家都十分重视对它的研究。王夫之在总结、继承前哲义利思想的基础上，提出了自己的义利观，并对义利进行了层次性及相对性的分析，既继承了传统道义论的精华，又极大地丰富了中国古代伦理思想的内涵。     

治安管理处罚非法证据排除规则

《中华人民共和国治安管理处罚法》首次明确规定了治安管理处罚非法证据排除规则，其价值取向在于保障私权、制约公权和维护程序公正。在执法实践中，需要充分考虑非法证据排除规则的价值取向以及我国的证据法传统和行政管理现实等相关因素，客观确定非法证据排除的范围。     

地区信息化水平的综合评价

本文从信息化的发展入手,阐述了信息化建设及各地区信息化水平评价的重要性,采用多元统计中的主成分分析和主成分回归法,设计一个综合指标用以评估各类地区的信息化水平及其在全国所处的位置,指导各地区的信息化建设。     

Backfitting Random Varying-Coefficient Models with Time-Dependent Smoothing Covariates

Abstract.  In this paper, we propose a random varying-coefficient model for longitudinal data. This model is different from the standard varying-coefficient model in the sense that the time-varying coefficients are assumed to be subject-specific, and can be considered as realizations of stochastic processes. This modelling strategy allows us to employ powerful mixed-effects modelling techniques to efficiently incorporate the within-subject and between-subject variations in the estimators of time-varying coefficients. Thus, the subject-specific feature of longitudinal data is effectively considered in the proposed model. A backfitting algorithm is proposed to estimate the coefficient functions. Simulation studies show that the proposed estimation methods are more efficient in finite-sample performance compared with the standard local least squares method. An application to an AIDS clinical study is presented to illustrate the proposed methodologies.     

Dementia Problem Behavior and the Production of Informal Caregiving Services

Informal caregivers of individuals with Alzheimer's disease spend a considerable amount of time providing care. In this paper, we use Grossman's health production and Becker's time allocation models to develop a model of informal care provision to elderly dementia patients. In our model, time inputs produce caregiving services, which provides utility to the caregiver, but reduces leisure. We assume that time is less productive of services on the margin as the disease progresses. In this framework, an increase in patients' disease severity does not necessarily increase informal caregiver time input. The cost of formal care establishes a reservation price for informal caregiving. When the costs of informal caregiving rise above this reservation level, the patient is institutionalized. We test empirically the effect of deterioration in the patients' condition, proxied by both disease severity and dementia problem behavior, on informal caregiving time. We find that dementia-related problem behaviors and functional limitations significantly increase inputs of informal caregiving time. Patients' problem behavior exerts a modifying effect on functional limitations, and patients' comorbidities have no effect on informal caregiving time.