An Exactification of the Monoid of Primitive Recursive Functions

We study the monoid of primitive recursive functions and investigate a onestep construction of a kind of exact completion, which resembles that of the familiar category of modest sets, except that the partial equivalence relations which serve as objects are recursively enumerable. As usual, these constructions involve the splitting of symmetric idempotents.     

Cut-Elimination and a Permutation-Free Sequent Calculus for Intuitionistic Logic

We describe a sequent calculus, based on work of Herbelin, of which the cut-free derivations are in 1-1 correspondence with the normal natural deduction proofs of intuitionistic logic. We present a simple proof of Herbelin's strong cut-elimination theorem for the calculus, using the recursive path ordering theorem of Dershowitz.     

Neighborhood Risk Factors for Recidivism: For Whom do they Matter?

Justice‐involved people vary substantially in their risk of reoffending. To date, recidivism prediction and prevention efforts have largely focused on individual‐level factors like antisocial traits. Although a growing body of research has examined the role of residential contexts in predicting reoffending, results have been equivocal. One reason for mixed results may be that an individual’s susceptibility to contextual influence depends upon his or her accumulated risk of reoffending. Based on a sample of 2218 people on probation in San Francisco, California, this study draws on observational and secondary data to test the hypothesis that individual risk moderates the effect of neighborhood factors on recidivism. Results from survival analyses indicate that individual risk interacts with neighborhood concentrated disadvantage and disorder—and these factors increase recidivism among people relatively low in individual risk, but not those at higher risk. This is consistent with the disadvantage saturation perspective, raising the possibility that some people classified as low risk might not recidivate but for placement in disadvantaged and disorderly neighborhoods. Ultimately, residential contexts “matter” for lower risk people and may be useful to consider in efforts to prevent recidivism.     

The pigeon's perception of saturation.

Three experiments used similar methods to investigate the pigeon's perception of saturation of monochromatic lights. This trial-wise procedure consisted of brief presentations of positive and negative stimuli in random sequence. Pecks to the positive stimuli were occasionally reinforced on a low fixed-ratio schedule. The first study determined absolute thresholds for "white" and monochromatic lights by establishing a discrimination between lights of various radiances and a dark key. Experiment II investigated generalization from a white light to various monochromatic lights under conditions that minimized the use of luminance as a cue. The third experiment examined discrimination of various monochromatic lights along a colorimetric purity continuum; responses to white light were reinforced, while responses to lights that combined white and monochromatic lights in various proportions were not. The results indicated that lights of different wavelength differ in saturation, but that all are discriminable from white. Wavelengths between 550 and 600 nm are least saturated for the pigeon, and saturation increases markedly as wavelength decreases below this region of the spectrum.     

照明环境与LCD显示界面背景饱和度的交互效应对视觉绩效的影响

摘 要 采用E-prime编排认知实验研究照明环境与TFT-LCD视觉显示终端界面背景饱和度的交互效应对视觉绩效的影响。依据字母视力表设计原理制作认知材料,以认知速度与准确率为视觉绩效评价指标。结果发现,照度与饱和度的交互效应对视觉绩效存在显著影响,色温与饱和度的交互效应仅对准确率存在显著影响,三因素交互作用对准确率存在显著影响。结果表明,不同照度、色温下,通过调节显示终端界面背景饱和度可改善视觉绩效。     

Defect formation in Nd2Fe14B grains caused by Zn diffusion

Defect formation in Nd₂Fe₁₄B grains, caused by a low-pressure-pack-sublimation Zn coating process, has been investigated. The results indicate that, in the Zn-affected region, low-angle boundaries decorated with precipitates form within the Nd2Fe14B grains. Zn, which is almost insoluble in Nd₂Fe₁₄     

Temporal logics for concurrent recursive programs: Satisfiability and model checking

We develop a general framework for the design of temporal logics for concurrent recursive programs. A program execution is modeled as a partial order with multiple nesting relations. To specify properties of executions, we consider any temporal logic whose modalities are definable in monadic second-order logic and which, in addition, allows PDL-like path expressions. This captures, in a unifying framework, a wide range of logics defined for ranked and unranked trees, nested words, and Mazurkiewicz traces that have been studied separately. We show that satisfiability and model checking are decidable in EXPTIME and 2EXPTIME, depending on the precise path modalities.     

质性研究中的资料饱和及其判定

在质性研究中,资料饱和通常被用以评估研究资料的充足性。但在研究实践中,资料饱和却存在概念模糊及操作性问题。作为某项质性研究所抽取的样本量已满足研究需要的标志,按照在研究过程中判定时点的先后顺序,资料饱和可划分为数据饱和、编码或主题饱和、意义饱和及理论饱和4种主要形式。4种形式的资料饱和各有其特定的内涵、评估方式和判定标准。研究认为,达到资料饱和的样本量标准不应统一设定,其检验需嵌入具体的研究过程;资料饱和存在逻辑上的不确定性,适度追加抽样有助于进一步确认;资料饱和作为考察研究质量的一项重要指标,并不适用于所有质性研究。