Invariants under image perspective transformations: Theory and examples

The objective of this work is to develop automated techniques for recognizing the same objects in images that differ in scale, tilt, and rotation. Such perspective transformations of images are produced when aerial images of the same scene are taken from different vantage points. The algebraic methods developed previously do not utilize the intensity values of the images, i.e., their pixel gray levels. Since image features essential for object recognition, such as edges and local image textures, may be described in terms of derivatives and integrals of the image intensity, it is necessary to investigate whether certain differential and integral operators applied to different perspective views of the same object are also invariant under the perspective transformation. We proceed to derive new differential operators and their corresponding integral invariants for curves and planar objects. We introduce a variant form of Fourier expansion specially adapted to the projective transformation. Extensions to three dimensions are discussed, as well as applications to other image formation models such as synthetic aperture radar (SAR). These results are steps toward a computational model for perspective-independent object recognition.     

自由的心

凯瑟琳(Kathryn)是一位年轻的平面与室内设计师,这套Loft公寓是她经历了多年的租屋生涯后的第次置业。虽然凯瑟琳一直梦想买一座都柏林市郊的乡村别墅来作为自己的梦想家园,但由于其价格远远超出她的财务能力,因此她开始在市区寻找各种适合自己的理想居所。     

Predictors and outcomes of joint trajectories of callous–unemotional traits and conduct problems in childhood.

Callous–unemotional (CU) traits are associated with antisocial and delinquent behaviors in children and represent a potential risk factor for adult psychopathy. However, there is a paucity of longitudinal research that explores the development of these traits, their longitudinal association with conduct problems (CP), and their psychosocial predictors and outcomes. Using a large sample of children followed longitudinally from the Twins Early Development Study (N = 9,578), we described the joint developmental trajectories of CU traits and CP during childhood (between ages 7 and 12) and examined the child- and family-level predictors (4 years old) and concomitant outcomes (12 years old) associated with the trajectories. The developmental trajectories were characterized with teachers' ratings of CU traits and CP from ages 7 to 12. Using general growth mixture modeling, we identified four trajectories of CU traits (stable high, increasing, decreasing, and stable low) and two trajectories of CP (high and low). Compared with the children who followed a low trajectory of CU traits and CP, those who followed a high trajectory of CU traits and CP had more negative child- and family-level predictors at 4 years (including CP, hyperactivity, negative parental discipline, and chaos in the home). Children with high or increasing levels of CU traits and concomitant high levels of CP presented the most negative outcomes at 12 years (including hyperactivity, peer problems, emotional problems, and negative parental feelings). Children with high CU traits and concomitant high levels of CP in childhood should be prioritized for targeted intervention. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Selective Inhibition of Heparan Sulphate and Not Chondroitin Sulphate Biosynthesis by a Small,Soluble Competitive Inhibitor

The glycosaminoglycan, heparan sulphate (HS), orchestrates many developmental processes. Yet its biological role has not yet fully been elucidated. Small molecule chemical inhibitors can be used to perturb HS function and these compounds provide cheap alternatives to genetic manipulation methods. However, existing chemical inhibition methods for HS also interfere with chondroitin sulphate (CS), complicating data interpretation of HS function. Herein, a simple method for the selective inhibition of HS biosynthesis is described. Using endogenous metabolic sugar pathways, Ac₄GalNAz produces UDP-GlcNAz, which can target HS synthesis. Cell treatment with Ac₄GalNAz resulted in defective chain elongation of the polymer and decreased HS expression. Conversely, no adverse effect on CS production was observed. The inhibition was transient and dose-dependent, affording rescue of HS expression after removal of the unnatural azido sugar. The utility of inhibition is demonstrated in cell culture and in whole organisms, demonstrating that this small molecule can be used as a tool for HS inhibition in biological systems.     

Effects of Edge-Stiffening Elements and Diaphragms on Bridge Resistance and Load Distribution

This research investigates the effects of barriers, sidewalks, and diaphragms (secondary elements) on bridge structure ultimate capacity and load distribution. Simple-span, two-lane highway girder bridges with composite steel and prestressed concrete girders are considered. The finite-element method is used for structural analysis. For the elastic range, typical secondary elements can reduce girder distribution factors (GDF) between 10 and 40%, depending on stiffness and bridge geometry. For the inelastic response, steel is modeled using von Mises yield criterion and isotropic (work) hardening. Concrete is modeled with a softening curve in compression with the ability to crack in tension. At ultimate capacity, typical secondary elements can reduce GDF an additional 5 to 20%, and bridge system ultimate capacity can be increased from 1.1 to 2.2 times that of the base bridge without secondary elements, depending on bridge geometry and secondary-element dimensions.     

Clean Manufacture of 2,4,6-Trinitrotoluene (TNT) via Improved Regioselectivity in the Nitration of Toluene

The U.S. Department of Defense requires an environmentally benign synthesis route to manufacture military grade trinitrotoluene (TNT), which eliminates the production of red water arising from the sulfiting process for removing unsymmetrical trinitrotoluene isomers. We have found that by using a novel nitrating system, N₂O₅ in dichloromethane, the proportion of metasubstituted nitrotoluenes can be suppressed, and improvements have also been made to the di- and trinitration steps. As a result, TNT with a set point near that of the Mil. Spec. can be made by our process, without the need for sulfite washing; after recrystallization it exceeds the specification.     

Theories of word naming interact with spelling--sound consistency.

In a previous study (E. Strain, K. Patterson, & M. S. Seidenberg, 1995), the authors concluded that word naming is characterized by an interaction between spelling-sound typicality and word imageability, thus implicating a role for word meaning in the naming process. J. Monaghan and A. W. Ellis (2002) reject E. Strain et al.'s conclusion, arguing that it is age of acquisition (AoA) and not imageability that interacts with spelling-sound typicality. In this article, the authors question their alternative interpretation (a) by raising a number of conceptual and methodological issues germane to this debate and (b) by presenting new data that confirm a significant interaction between spelling-sound typicality and imageability in word-naming latencies, an interaction that is reliable when word AoA is controlled in a regression analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluating the efficiency and temporal variation of pilot-scale constructed wetlands and steel slag phosphorus removing filters for treating dairy wastewater

The performance and temporal variation of three hybrid and three integrated, saturated flow, pilot-scale constructed wetlands (CWs) were tested for treating dairy farm effluent. The three hybrid systems each consisted of two CWs in-series, with horizontal and vertical flow. Integrated systems consisted of a CW (horizontal and vertical flow) followed by a steel slag filter for removing phosphorus. Time series temporal semivariogram analyses of measured water parameters illustrated different treatment efficiencies existed over the course of one season. As a result, data were then divided into separate time period groups and CW systems were compared using ANOVA for parameter measurements within each distinct time period group. Both hybrid and integrated CWs were efficient in removing organics; however, hybrid systems had significantly higher performance (p < 0.05) during peak vegetation growth. Compared to hybrid CWs, integrated CWs achieved significantly higher DRP reduction (p < 0.05) throughout the period of investigation and higher ammonia reduction (p < 0.05) in integrated CWs was observed in late summer. Geochemical modeling demonstrates hydroxyapatite and vivianite minerals forming on steel slag likely control the fate of phosphate ions given the reducing conditions prevalent in the system. The model also demonstrates how the wastewater:slag ratio can be adjusted to maximize phosphorus removal while staying at a near-neutral pH.     

A survey of current cost estimating practices in the UK

The results are documented of an investigation into current cost estimating practices of contractors for construction projects. A questionnaire survey of contractors was undertaken, in which the respondents are classified into four groups based on their turnover namely: very small, small, medium and large firms. The survey indicates that contractors, irrespective of size, continue to undertake cost estimating predominantly for construction planning purposes, including the preparation of tenders and cost control of projects during the execution stage and, to a lesser extent, for construction project evaluation. Recent developments in cost estimating methods and tools that consider risks and variability in cost estimates, such as the use of range estimating and parametric estimating techniques, have not been adopted by contractors. The practice of cost estimating does not differ from conventional techniques based on the use of labour and material constants to obtain prices for bills of quantities items on an item by item basis. The study shows that the major causes of inaccuracy in cost estimating continue to be the lack of practical knowledge of the construction process by those responsible for the estimating function, insufficient time to prepare cost estimates, poor tender documentation and the wide variability of subcontractors' prices.     

New evidence for rejuvenation of phosphorus retention capacity in EAF steel slag

The purpose of this research was to investigate phosphorus (P) retention capacity and rejuvenation potential of electric arc furnace (EAF) steel slag from Quebec and New Zealand (NZ) iron melter slag (IMS). Columns filled with slag materials were fed with dairy effluent and subjected to two feeding and one resting cycle(s). P retention capacities and rejuvenation potentials were determined after each feeding cycle. Elemental composition and mineralogical analysis were performed on IMS samples. Finally, chemical fractionation analysis was conducted on both NZ IMS and Quebec EAF steel slags. The results revealed that initiating a resting period in EAF steel slag filters prior to reaching their P saturation point increased the overall filter P retention capacity by 49.5 and 42.4% compared to 28% in a filter which had its resting period initiated after reaching P saturation. The rejuvenation property could play a significant role in full-scale applications by prolonging life expectancy and increasing cost efficiency. P retention and rejuvenation by NZ slag materials was negligible relative to EAF steel slag material from Quebec. Chemical fractionation analysis revealed differences between materials, indicating that the highest quantities of P were bound to Ca and Fe in EAF steel slag and to Ca and Al fractions in iron melter slag. This study also demonstrates that slag's performance is dependent on the source of the material and the steel making practices. Therefore, testing of the P adsorptive capability and, if relevant, the rejuvenation potential of individual steel mill slags, should be a prerequisite prior to their use in field applications.