Succinct Posets

We describe an algorithm for compressing a partially ordered set, or \emph{poset}, so that it occupies space matching the information theory lower bound (to within lower order terms), in the worst case. Using this algorithm, we design a succinct data structure for representing a poset that, given two elements, can report whether one precedes the other in constant time. This is equivalent to succinctly representing the transitive closure graph of the poset, and we note that the same method can also be used to succinctly represent the transitive reduction graph. For an $n$ element poset, the data structure occupies $n^2/4 + o(n^2)$ bits, in the worst case, which is roughly half the space occupied by an upper triangular matrix. Furthermore, a slight extension to this data structure yields a succinct oracle for reachability in arbitrary directed graphs. Thus, using roughly a quarter of the space required to represent an arbitrary directed graph, reachability queries can be supported in constant time.Comment: 12 pages lncs format + short appendi

Introducing a novel mesh following technique for approximation-free robotic tool path trajectories

Modern tools for designing and manufacturing of large components with complex geometries allow more flexible production with reduced cycle times. This is achieved through a combination of traditional subtractive approaches and new additive manufacturing processes. The problem of generating optimum tool-paths to perform specific actions (e.g. part manufacturing or inspection) on curved surface samples, through numerical control machinery or robotic manipulators, will be increasingly encountered. Part variability often precludes using original design CAD data directly for toolpath generation (especially for composite materials), instead surface mapping software is often used to generate tessellated models. However, such models differ from precise analytical models and are often not suitable to be used in current commercially available path-planning software, since they require formats where the geometrical entities are mathematically represented thus introducing approximation errors which propagate into the generated toolpath. This work adopts a fundamentally different approach to such surface mapping and presents a novel Mesh Following Technique (MFT) for the generation of tool-paths directly from tessellated models. The technique does not introduce any approximation and allows smoother and more accurate surface following tool-paths to be generated. The background mathematics to the new MFT algorithm are introduced and the algorithm is validated by testing through an application example. Comparative metrology experiments were undertaken to assess the tracking performance of the MFT algorithms, compared to tool-paths generated through commercial software. It is shown that the MFT tool-paths produced 40% smaller errors and up to 66% lower dispersion around the mean values

Robotic path planning for non-destructive testing of complex shaped surfaces

The requirement to increase inspection speeds for non-destructive testing (NDT) of composite aerospace parts is common to many manufacturers. The prevalence of complex curved surfaces in the industry provides significant motivation for the use of 6 axis robots for deployment of NDT probes in these inspections. A new system for robot deployed ultrasonic inspection of composite aerospace components is presented. The key novelty of the approach is through the accommodation of flexible robotic trajectory planning, coordinated with the NDT data acquisition. Using a flexible approach in MATLAB, the authors have developed a high level custom toolbox that utilizes external control of an industrial 6 axis manipulator to achieve complex path planning and provide synchronization of the employed ultrasonic phase array inspection system. The developed software maintains a high level approach to the robot programming, in order to ease the programming complexity for an NDT inspection operator. Crucially the approach provides a pathway for a conditional programming approach and the capability for multiple robot control (a significant limitation in many current off-line programming applications). Ultrasonic and experimental data has been collected for the validation of the inspection technique. The path trajectory generation for a large, curved carbon-fiber-reinforced polymer (CFRP) aerofoil component has been proven and is presented. The path error relative to a raster-scan tool-path, suitable for ultrasonic phased array inspection, has been measured to be within ± 2mm over the 1.6 m2 area of the component surface

Baseline study of employability related activities in Scottish colleges

In October 2004, the Scottish Funding Council (SFC)'s predecessor bodies, theSFEFC and the SHEFC, publishedLearning to Work(SFC 2004), a discussion paperabout how Scotland's colleges and universities can help to enhance learners'employability. In subsequent dialogue with stakeholders, there was agreement thatemployability should be a specific focus for quality enhancement in the college sectorfrom 2006-07. As a basis for further development, the SFC commissioned this studyto provide information on the range of current activities and practices in Scotland'scolleges which contribute to enhancing employability

Marginal adaptation and performance of bioactive dental restorative materials in deciduous and young permanent teeth.

The aim of this study was to investigate the adaptation of different types of restorations towards deciduous and young permanent teeth. Class V cavities were prepared in deciduous and young permanent teeth and filled with different materials (a conventional glass-ionomer, a resin-modified glass-ionomer, a poly-acid-modified composite resin and a conventional composite resin). Specimens were aged in artificial saliva for 1, 6, 12 and 18 months, then examined by SEM. The composite resin and the polyacid-modified composite had better marginal adaptation than the glass-ionomers, though microcracks developed in the enamel of the tooth. The glass-ionomers showed inferior marginal quality and durability, but no microcracking of the enamel. The margins of the resin-modified glass-ionomer were slightly superior to the conventional glass-ionomer. Conditioning improved the adaptation of the composite resin, but the type of tooth made little or no difference to the performance of the restorative material. All materials were associated with the formation of crystals in the gaps between the filling and the tooth; the quantity and shape of these crystals varied with the material. Resin-based materials are generally better at forming sound, durable margins in deciduous and young permanent teeth than cements, but are associated with microcracks in the enamel. All fluoride-releasing materials give rise to crystalline deposits

Hippurate: the natural history of a mammalian-microbial co-metabolite

Hippurate, the glycine conjugate of benzoic acid, is a normal constituent of the endogenous urinary metabolite profile and has long been associated with the microbial degradation of certain dietary components, hepatic function and toluene exposure, and is also commonly used as a measure of renal clearance. Here we discuss the potential relevance of hippurate excretion with regards to normal endogenous metabolism and trends in excretion relating to gender, age, and the intestinal microbiota. Additionally, the significance of hippurate excretion with regards to disease states including obesity, diabetes, gastrointestinal diseases, impaired renal function, psychological disorders and autism, as well as toxicity and parasitic infection, are considered

Gut microbiota modulation of chemotherapy efficacy and toxicity

Evidence is growing that the gut microbiota modulates the host response to chemotherapeutic drugs, with three main clinical outcomes: facilitation of drug efficacy; abrogation and compromise of anticancer effects; and mediation of toxicity. The implication is that gut microbiota are critical to the development of personalized cancer treatment strategies and, therefore, a greater insight into prokaryotic co-metabolism of chemotherapeutic drugs is now required. This thinking is based on evidence from human, animal and in vitro studies that gut bacteria are intimately linked to the pharmacological effects of chemotherapies (5-fluorouracil, cyclophosphamide, irinotecan, oxaliplatin, gemcitabine, methotrexate) and novel targeted immunotherapies such as anti-PD-L1 and anti-CLTA-4 therapies. The gut microbiota modulate these agents through key mechanisms, structured as the 'TIMER' mechanistic framework: Translocation, Immunomodulation, Metabolism, Enzymatic degradation, and Reduced diversity and ecological variation. The gut microbiota can now, therefore, be targeted to improve efficacy and reduce the toxicity of current chemotherapy agents. In this Review, we outline the implications of pharmacomicrobiomics in cancer therapeutics and define how the microbiota might be modified in clinical practice to improve efficacy and reduce the toxic burden of these compounds

Conspicuous Space: Parking Lot Suburbanism

What can be accomplished without a car? In a city: everything. In a suburb: nothing. Without a car, one cannot escape the city. Without a city, one cannot escape the car. Neither city nor suburb is an ideal habitat. The city has no nature. The suburb has no culture. What’s good about the suburbs over the city? According to economics: houses. The American dream has long been “one’s own house with a private yard” (Nelesson xi); an acre and a mule for every free citizen. But this dream has created distance; a nightmare of endless commutes and oil addiction. What if we could bridge that distance, without reverting to the “city?” What if the suburbs “are almost all right” (Venturi 6)? What should we move and where should we move it? Perhaps instead of building our subdivisions of mass-customized dream homes in rapidly disappearing virgin forests, grasslands, farmlands, and other productive ecosystems, we could find a place that is already underused, ugly, obsolete, and vast. Sound familiar? How about surface parking lots?! By relocating the single-family house into the parking lot of the shopping center, (I contend that) a place is created that is neither city nor suburb: it is both city and suburb; a place that is neither sprawling nor dense: it is sprawling and dense. This type will neither occupy nor preserve the conspicuous space of the consumerist suburb; it will both occupy and preserve it. Just as the “motorized city that tries to overcome distance... tries to make distance at the same time” (Lerup 40) this new place will be both space and object, figure and field, community and privacy. Is it a parking lot or is it a suburban neighborhood? Both. And neither. Where are the lines drawn between public and private? They are not drawn, but inferred. This type is meant to be both ubiquitous and pliable, both subtle and overbearing; just like the separate types that it is consuming (house and big box). This place shall remain nameless, open-ended, and subject to interpretation, just like the environment it is to inhabit (the city outside the city). This place is not meant to replace, but to exist in parallel and serve as an alternative to the single-use zoned suburb, the traditional city, the modern downtown, and whatever other settlement patterns the future holds. With this thesis, I mean simply to add another item to the menu of urban conditions from which the discerning consumer of space and habitat will choose his preferred built environment. Hopefully, if this kind of scheme were realized in the real world, it would help to slow suburban sprawl and positively impact the built environment and the natural environment that supports it. However, this thesis is concerned explicitly with the ability of this strategy to be an architecturally viable alternative to more straightforward scheme of simple re-urbanization, as the New Urbanists would propose. Consumerism is not being questioned here. Automobility is not being questioned here. I simply mean to argue that the vast amounts of space wasted by suburban parking lots could be used as a viable alternative site to the virgin wilderness or farmland, and that those parking lots have inherent architectural qualities that are worth investigating. Nelessen, Anton C. Visions for a New American Dream. Chicago: American Planning Association, 1994. xi. New Urbanism: Peter Calthorpe vs. Lars Lerup. Ed. Robert Fishman. New York: Arts Press, 2005. 40. (quoting Lars Lerup) Venturi, Robert, et. al. Learning from Las Vegas. Revised Edition. Cambridge: MIT Press, 1977. 6

A comparison of collision cross section values obtained via travelling wave ion mobility-mass spectrometry and ultra high performance liquid chromatography-ion mobility-mass spectrometry : application to the characterisation of metabolites in rat urine

A comprehensive Collision Cross Section (CCS) library was obtained via Travelling Wave Ion Guide mobility measurements through direct infusion (DI). The library consists of CCS and Mass Spectral (MS) data in negative and positive ElectroSpray Ionisation (ESI) mode for 463 and 479 endogenous metabolites, respectively. For both ionisation modes combined, TWCCSN2 data were obtained for 542 non-redundant metabolites. These data were acquired on two different ion mobility enabled orthogonal acceleration QToF MS systems in two different laboratories, with the majority of the resulting TWCCSN2 values (from detected compounds) found to be within 1% of one another. Validation of these results against two independent, external TWCCSN2 data sources and predicted TWCCSN2 values indicated to be within 1-2% of these other values. The same metabolites were then analysed using a rapid reversed-phase ultra (high) performance liquid chromatographic (U(H)PLC) separation combined with IM and MS (IM-MS) thus providing retention time (tr), m/z and TWCCSN2 values (with the latter compared with the DI-IM-MS data). Analytes for which TWCCSN2 values were obtained by U(H)PLC-IM-MS showed good agreement with the results obtained from DI-IM-MS. The repeatability of the TWCCSN2 values obtained for these metabolites on the different ion mobility QToF systems, using either DI or LC, encouraged the further evaluation of the U(H)PLC-IM-MS approach via the analysis of samples of rat urine, from control and methotrexate-treated animals, in order to assess the potential of the approach for metabolite identification and profiling in metabolic phenotyping studies. Based on the database derived from the standards 63 metabolites were identified in rat urine, using positive ESI, based on the combination of tr, TWCCSN2 and MS data.</p