Validation of purdue engineering shape benchmark clusters by crowdsourcing

The effective organization of CAD data archives is central to PLM and consequently content based retrieval of 2D drawings and 3D models is often seen as a "holy grail" for the industry. Given this context, it is not surprising that the vision of a "Google for shape", which enables engineers to search databases of 3D models for components similar in shape to a query part, has motivated numerous researchers to investigate algorithms for computing geometric similarity. Measuring the effectiveness of the many approaches proposed has in turn lead to the creation of benchmark datasets against which researchers can compare the performance of their search engines. However to be useful the datasets used to measure the effectiveness of 3D retrieval algorithms must not only define a collection of models, but also provide a canonical specification of their relative similarity. Because the objective of shape retrieval algorithms is (typically) to retrieve groups of objects that humans perceive as "similar" these benchmark similarity relationships have (by definition) to be manually determined through inspection

Geometric reasoning via internet crowdsourcing

The ability to interpret and reason about shapes is a peculiarly human capability that has proven difficult to reproduce algorithmically. So despite the fact that geometric modeling technology has made significant advances in the representation, display and modification of shapes, there have only been incremental advances in geometric reasoning. For example, although today's CAD systems can confidently identify isolated cylindrical holes, they struggle with more ambiguous tasks such as the identification of partial symmetries or similarities in arbitrary geometries. Even well defined problems such as 2D shape nesting or 3D packing generally resist elegant solution and rely instead on brute force explorations of a subset of the many possible solutions. Identifying economic ways to solving such problems would result in significant productivity gains across a wide range of industrial applications. The authors hypothesize that Internet Crowdsourcing might provide a pragmatic way of removing many geometric reasoning bottlenecks.This paper reports the results of experiments conducted with Amazon's mTurk site and designed to determine the feasibility of using Internet Crowdsourcing to carry out geometric reasoning tasks as well as establish some benchmark data for the quality, speed and costs of using this approach.After describing the general architecture and terminology of the mTurk Crowdsourcing system, the paper details the implementation and results of the following three investigations; 1) the identification of "Canonical" viewpoints for individual shapes, 2) the quantification of "similarity" relationships with-in collections of 3D models and 3) the efficient packing of 2D Strips into rectangular areas. The paper concludes with a discussion of the possibilities and limitations of the approach

Matriarch: A Python Library for Materials Architecture

Biological materials, such as proteins, often have a hierarchical structure ranging from basic building blocks at the nanoscale (e.g., amino acids) to assembled structures at the macroscale (e.g., fibers). Current software for materials engineering allows the user to specify polypeptide chains and simple secondary structures prior to molecular dynamics simulation, but is not flexible in terms of the geometric arrangement of unequilibrated structures. Given some knowledge of a larger-scale structure, instructing the software to create it can be very difficult and time-intensive. To this end, the present paper reports a mathematical language, using category theory, to describe the architecture of a material, i.e., its set of building blocks and instructions for combining them. While this framework applies to any hierarchical material, here we concentrate on proteins. We implement this mathematical language as an open-source Python library called Matriarch. It is a domain-specific language that gives the user the ability to create almost arbitrary structures with arbitrary amino acid sequences and, from them, generate Protein Data Bank (PDB) files. In this way, Matriarch is more powerful than commercial software now available. Matriarch can be used in tandem with molecular dynamics simulations and helps engineers design and modify biologically inspired materials based on their desired functionality. As a case study, we use our software to alter both building blocks and building instructions for tropocollagen, and determine their effect on its structure and mechanical properties.Center for Excellence in Education. Research Science InstituteUnited States. Office of Naval Research. Presidential Early Career Award for Scientists and Engineers (N000141010562)United States. Air Force. Office of Scientific Research (FA9550-11-1-0199)United States. Army Research OfficeNational Institutes of Health (U.S.) (5U01EB016422)National Institutes of Health (U.S.) (EB014976)BASF. North American Center for Research on Advanced Material

2-Hy­droxy­ethyl 4-hy­droxy­benzoate

In the title compound, C9H10O4, the dihedral angle between the benzene ring and the –CO2 unit is 11.93 (8)° and the conformation of the 2-hy­droxy­ethyl side chain is gauche [O—C—C—O = −71.91 (17)°]. In the crystal, mol­ecules are linked by O—H⋯O and C—H⋯O hydrogen bonds

The problem of programming language concurrency semantics

Despite decades of research, we do not have a satisfactory concurrency semantics for any general-purpose programming language that aims to support concurrent systems code. The Java Memory Model has been shown to be unsound with respect to standard compiler optimisations, while the C/C++11 model is too weak, admitting undesirable thin-air executions. Our goal in this paper is to articulate this major open problem as clearly as is currently possible, showing how it arises from the combination of multiprocessor relaxed-memory behaviour and the desire to accommodate current compiler optimisations. We make several novel contributions that each shed some light on the problem, constraining the possible solutions and identifying new difficulties. First we give a positive result, proving in HOL4 that the existing axiomatic model for C/C++11 guarantees sequentially consistent semantics for simple race-free programs that do not use low-level atomics (DRF-SC, one of the core design goals). We then describe the thin-air problem and show that it cannot be solved, without restricting current compiler optimisations, using any per-candidate-execution condition in the style of the C/C++11 model. Thin-air executions were thought to be confined to programs using relaxed atomics, but we further show that they recur when one attempts to integrate the concurrency model with more of C, mixing atomic and nonatomic accesses, and that also breaks the DRF-SC result. We then describe a semantics based on an explicit operational construction of out-of-order execution, giving the desired behaviour for thin-air examples but exposing further difficulties with accommodating existing compiler optimisations. Finally, we show that there are major difficulties integrating concurrency semantics with the C/C++ notion of undefined behaviour. We hope thereby to stimulate and enable research on this key issue

Relative tolerance and expression of resistance to phosphine in life stages of the rusty grain beetle, Cryptolestes ferrugineus

Cryptolestes ferrugineus is a serious cosmopolitan pest of stored products. Frequent and indiscriminate usage of phosphine has caused the development of high levels of resistance to this fumigant. As there are few alternatives, it is imperative that resistance to phosphine is managed. Effective management requires knowledge of key factors driving the rate of selection. One of the most important factors is the response of each resistance genotype to phosphine, especially heterozygotes. Moreover, it is important to understand the expression of resistance in all life stages as all stages are subjected to selection during fumigation. We determined the relative tolerance and resistance levels to phosphine in all life stages of homozygous parental strains (susceptible and resistant) and their F1 progeny (heterozygous) and estimated relative dominance of resistance within life stages over 48 h. In susceptible insects, relative tolerance was highest in eggs followed by pupae, then adults which had about the same tolerance as larvae. In homozygous resistant insects, the order of tolerance was adult = egg > pupae > larvae and in heterozygotes larvae > eggs > pupae > adults. All life stages expressed resistance with resistance ratios highest in adults > pupae > larvae > eggs. At LC50, resistance was incompletely recessive in eggs, pupae and adults and incompletely dominant in larvae. Eggs and adults were also incompletely recessive at LC95, but larvae were completely dominant and pupae were incompletely dominant. Our data showed that a proportion of heterozygotes in all life stages, the major carriers of resistance in the field, will survive at very high concentrations, particularly in the egg stage, forming a nucleus for reinfestation or dispersal of resistance

Transactions in Relaxed Memory Architectures

The integration of transactions into hardware relaxed memory architectures is a topic of current research both in industry and academia. In this paper, we provide a general architectural framework for the introduction of transactions into models of relaxed memory in hardware, including the sc, tso, armv8 and ppc models. Our framework incorporates flexible and expressive forms of transaction aborts and execution that have hitherto been in the realm of software transactional memory. In contrast to software transactional memory, we account for the characteristics of relaxed memory as a restricted form of distributed system, without a notion of global time. We prove abstraction theorems to demonstrate that the programmer API matches the intuitions and expectations about transactions

Gene introgression in assessing fitness costs associated with phosphine resistance in the rusty grain beetle

The current study investigates the fitness cost associated with phosphine resistance in the rusty grain beetle, Cryptolestes ferrugineus (Stephens), a problematic pest in the stored commodities that has developed strong resistance to fumigant phosphine. Three characterised insect strains: the susceptible (Ref-S), the strongly resistant (Ref-R), the introgressed resistant (Intro-R) and a segregating population (F25) derived from crossing the Ref-S and Ref-R strains were used in this study. Intro-R was developed by introgressing two phosphine resistance genes, cf_rph1 and cf_rph2 into Ref-S, aimed to reduce the influence of background genetic factors. Intro-R exhibited 592 × resistance to phosphine and homozygous for strong resistance allele, cf_rph2 (L73N). Two key fitness cost criteria, developmental time and fecundity, were assessed under optimal and suboptimal conditions (less favourable diet and low temperature). There was no significant difference in developmental time and fecundity between Ref-S and either Intro-R strain or F25 under optimal conditions. When challenged with a less favourable diet, cracked wheat + cracked sorghum (CW + CS), or exposed to a low temperature (22 °C), both Intro-R and Ref-S had similar developmental time and total numbers of F1 progeny, confirming the absence of significant fitness effects expressed in these conditions. Therefore, we conclude that strongly phosphine resistant C. ferrugineus are unlikely to incur potential fitness costs. This finding will have implications towards developing strategies to manage this pest

Potential for using pheromone trapping and molecular screening in phosphine resistance research: Presentation

Phosphine resistance monitoring typically involves bioassays of beetles from population samples collected from grain storage facilities. Insects are classified into susceptible or resistant phenotypes based on mortality or survival at one or more discriminating doses. Although valuable, phenotype testing has several drawbacks. First, phenotype testing needs live insects, and considerable effort is required to collect and maintain them before testing. Second, population samples may contain multiple genotypes expressing different levels of resistance that may not be distinguishable using discriminating dose bioassays. Third, collections are likely to be focussed around grain storages to maximise sampling success. Recent research shows that several key pests are actively dispersing through flight. The availability of commercial pheromone lures and recent advances in molecular screening provide an opportunity to provide information on resistance gene frequencies more broadly across the landscape. This approach is proving to be a valuable adjunct to traditional resistance testing in Australia.Phosphine resistance monitoring typically involves bioassays of beetles from population samples collected from grain storage facilities. Insects are classified into susceptible or resistant phenotypes based on mortality or survival at one or more discriminating doses. Although valuable, phenotype testing has several drawbacks. First, phenotype testing needs live insects, and considerable effort is required to collect and maintain them before testing. Second, population samples may contain multiple genotypes expressing different levels of resistance that may not be distinguishable using discriminating dose bioassays. Third, collections are likely to be focussed around grain storages to maximise sampling success. Recent research shows that several key pests are actively dispersing through flight. The availability of commercial pheromone lures and recent advances in molecular screening provide an opportunity to provide information on resistance gene frequencies more broadly across the landscape. This approach is proving to be a valuable adjunct to traditional resistance testing in Australia