bluuebunny/crossref_metadata_2025 huggingface dataset:
How do you model the future?
Authors: Maslin Mark
Published: September 2013

‘How do you model the future?’ considers the carbon cycle, cooling effects, and carbon emissions to show that climate models suggest the global mean surface temperature could rise by between 1.1°C and 6.4°C by 2100. The models also predict an increase in global mean sea level of between 18cm and 59cm, although this could be higher if melting of Greenland and Antarctica are included and a non-linear response is seen. Some leading climate scientists have voiced their concern that the IPCC 2007 predictions are too conservative and suggest that, to save the ice sheets, a return to a global level of 350ppm is needed as quickly as possible.
What are the possible future impacts?
Authors: Maslin Mark
Published: September 2013

‘What are the possible future impacts?’ indicates the significant and wide-ranging effects of global warming effects on the natural environment as well as on human societies and our economies. Extreme climate events as a result of global warming — storms, floods, heatwaves, droughts — will increase. The role of the El Niño–Southern Oscillation, which is linked to changes in the monsoon, storm patterns, and occurrence of droughts all over the world, is explained. Water security, food security, and public health will become the most important problems facing all countries. Global warming also threatens global biodiversity and the wellbeing of billions of people.
Surprises
Authors: Maslin Mark
Published: September 2013

‘Surprises’ shows that the assumption of a linear relationship between greenhouse gases and climate change may be wrong. There may be potential surprises in the global climate system, exacerbating future climate change. These include the possibility that Greenland and/or the Antarctic could melt, raising sea level by metres; a change in North Atlantic-driven deep-ocean circulation producing extreme seasonal weather in Europe; a reduction of the Amazon rainforest that could accelerate global warming and destroy biodiversity; and finally, a release of gas hydrates from deep beneath the oceans could occur if the oceans warm up sufficiently, again accelerating global warming.
Conclusion
Authors: Maslin Mark
Published: September 2013

The ‘Conclusion’ confirms that global warming is the major challenge for our global society. There is very little doubt that global warming will change our climate in the next century. So what are the solutions to global warming? First, there must be an international political solution. Second, funding for developing cheap and clean energy production must be increased, as all economic development is based on increasing energy usage. We must not pin all our hopes on global politics and clean energy technology, so we must prepare for the worst and adapt. If implemented now, a lot of the costs and damage that could be caused by changing climate can be mitigated.
Introduction: initial observations
Authors: Davies Owen
Published: September 2013

What does magic mean to scholars, non-scholars, scientists, writers, primitive societies, and modern cultures? ‘Introduction: initial observations’ asks How do you define magic? The Ancient Greek origins of the word ‘magic’ describe mysterious Babylonian cult rituals. The word was carried forward by Christianity, Islam, and Judaism. Magic has been an accusation. The major religions have all accused rival religions of magic in an attempt to discredit them and legitimize themselves. Accusations of magic have been used within religions to allow particular factions to gain dominance. Magic also belongs to ‘folk’ religions and Paganism. Fear of ‘black magic’ still exists today, as do religions based on magic, such as Vodou (Haiti).
Historical perspectives
Authors: Davies Owen
Published: September 2013

Where do people think magic came from and how have histories of magic influenced our view of it? ‘Historical perspectives’ shows how written histories of magic have typically been informed by a sense of Western superiority and have been religiously and culturally biased. What is the difference between superstition and magic? For many societies, superstition and magic were the difference between good and bad religion. In Christianity, magic was Paganism (bad religion), connected to the devil. In the early 1500s laws against witchcraft were enacted across Europe — these were laws against magic. But scientific explorations of magic also took place, such as Isaac Newton's pursuit of alchemy pushed scientific discovery forwards.
All in the mind?
Authors: Davies Owen
Published: September 2013

There is a long history of scepticism regarding magic. ‘All in the mind? ’ looks at magicians, witchcraft, and psychoanalysis. In 16th-century England Reginald Scot learned the tricks of the trade of street magicians then wrote a book exposing them. He pointed out the similarities between witches who were being killed for their ‘trickery’ and magicians who were making a living plying their trade. In the 19th and 20th centuries depression was seen as a source of magic; women were viewed as hysterics, and so were connected to magic. Attempts to define magic continue, with the formulation of the Paranormal Belief Scale (PBS) in the 1980s.
Form, or, what's contemporary about contemporary fiction?
Authors: Eaglestone Robert
Published: September 2013

‘Form, or, what's contemporary about contemporary fiction?’ considers how writers explore the form of the novel. While most novels published are realist, three areas of challenge to this realism seem special to the last ten years. The first is a retreat from the wilder edges of postmodernism towards a stronger sense of narrative while retaining postmodern fiction's playfulness and complexity over issues like textuality and closure. The second is a renewed interest in techniques of high modernism, associated with Woolf and Joyce. The third involves the demolition of the barriers between the realms of fiction and non-fiction writing. All three have a nuanced approach to the central issue of closure.
The past
Authors: Eaglestone Robert
Published: September 2013

‘The past’ points out that novels have always been interested in the past, in history, and in memory. Contemporary fiction often rejects the traditional historical novel, instead exploring memory, trauma, and how the past haunts the present. Our stories about the past shift and develop. Because we are, in part, shaped by the stories we tell about our pasts, these changes, in turn, mean that our sense of ourselves changes, too: our past is always about our present. Contemporary fiction not only reflects these quite normal changes but also investigates how we relate not just to the events of the past but to our experience of ‘pastness’ itself.
The future
Authors: Eaglestone Robert
Published: September 2013

The image of the future in contemporary fiction is inseparable from ideas about the impact of technology: expressions of hope or despair about that future are measured through the figure of the child. It is technology that allows us history, as a recorded past, and so a present and a future. According to ‘The future’, to think about technology is to think about the very core of what we, as a species, are. As we change technology, we change ourselves. Contemporary fiction ‘thinks’ about technology in different ways each of which has a different use of the idea of the child, the inchoate figure of future hope or despair.
What are trust and distrust?
Authors: Hawley Katherine
Published: September 2013

Trust plays a huge part in how we run our lives. At a basic level, we trust or distrust the inanimate objects around us such as kitchen chairs and sharp knives. At this level, trusting or distrusting doesn't have the moral overtones or complexity of interpersonal trust or distrust. There is no sense of blame. ‘What are trust and distrust?’ looks at the definitions of these two concepts. Trustworthiness is the challenge of deciding who to trust. It is a noble attribute; appearing to be a moral virtue yet it can exist in corrupted relationships. How do we decide to trust or distrust?
Chemical modifications on siRNAs avoid Toll-like-receptor-mediated activation of the hepatic immune system in vivo and in vitro
Authors: Broering Ruth , Real Catherine I. , John Matthias J. , Jahn-Hofmann Kerstin , Ickenstein Ludger M. , Kleinehr Kathrin , Paul Andreas , Gibbert Kathrin , Dittmer Ulf , Gerken Guido , Schlaak Joerg F.
Published: September 2013

Objectives:

The therapeutic application of small interfering RNAs (siRNAs) is limited by the induction of severe off-target effects, especially in the liver. Therefore, we assessed the potential of differently modified siRNAs to induce the hepatic innate immune system in vitro and in vivo.

Methods:

Primary isolated liver cells were transfected with siRNAs against apolipoprotein B1 (APOB1), luciferase (LUC) or galactosidase (GAL). For in vivo use, siRNAs were formulated in lipid nanoparticles (LNPs) and administered intravenously to C57BL/6 mice. Liver tissue was collected 6–48h after injection and knock-down efficiency or immune responses were determined by quantitative reverse-transcription-linked PCR.

Results:

Unmodified GAL siRNA transiently induced the expression of TNF-α, IL-6, IL-10, IFN-β and IFN-sensitive gene 15 in vivo, whereas a formulation of 2′-O-methylated-LUC siRNA had no such effects. Formulation of unmodified APOB1-specific siRNA suppressed APOB1 mRNA levels by ~80% in the liver 48h after application. The results were paralleled in vitro, where transfection of liver cells with unmodified siRNAs, but not with chemically modified siRNAs, led to cell-type-specific induction of immune genes. These immune responses were not observed in MYD88-deficient mice or in chloroquine-treated cells in vitro.

Conclusions:

Our data indicate that siRNAs activate endosomal Toll-like receptors in different liver-derived cell types to various degrees, in vitro. LNP-formulated siRNA selectively leads to hepatic knock-down of target genes in vivo. Here, off-target immune responses are restricted to non-parenchymal liver cells. However, 2′-O-methyl modifications of siRNA largely avoid immune-stimulatory effects, which is a crucial prerequisite for the development of safe and efficient RNA-interference-based therapeutics.
Scoring from Contests
Authors: Schnakenberg Keith E. , Penn Elizabeth Maggie
Published: September 2013

This article presents a new model for scoring alternatives from “contest” outcomes. The model is a generalization of the method of paired comparison to accommodate comparisons between arbitrarily sized sets of alternatives in which outcomes are any division of a fixed prize. Our approach is also applicable to contests between varying quantities of alternatives. We prove that under a reasonable condition on the comparability of alternatives, there exists a unique collection of scores that produces accurate estimates of the overall performance of each alternative and satisfies a well-known axiom regarding choice probabilities. We apply the method to several problems in which varying choice sets and continuous outcomes may create problems for standard scoring methods. These problems include measuring centrality in network data and the scoring of political candidates via a “feeling thermometer.” In the latter case, we also use the method to uncover and solve a potential difficulty with common methods of rescaling thermometer data to account for issues of interpersonal comparability.
Density-functional theory study of gramicidin A ion channel geometry and electronic properties
Authors: Todorović Milica , Bowler David R. , Gillan Michael J. , Miyazaki Tsuyoshi
Published: September 2013

Understanding the mechanisms underlying ion channel function from the atomic-scale requires accurate
ab initio
modelling as well as careful experiments. Here, we present a density functional theory (DFT) study of the ion channel gramicidin A (gA), whose inner pore conducts only monovalent cations and whose conductance has been shown to depend on the side chains of the amino acids in the channel. We investigate the ground state geometry and electronic properties of the channel in vacuum, focusing on their dependence on the side chains of the amino acids. We find that the side chains affect the ground state geometry, while the electrostatic potential of the pore is independent of the side chains. This study is also in preparation for a full, linear scaling DFT study of gA in a lipid bilayer with surrounding water. We demonstrate that linear scaling DFT methods can accurately model the system with reasonable computational cost. Linear scaling DFT allows
ab initio
calculations with 10 000–100 000 atoms and beyond, and will be an important new tool for biomolecular simulations.
The Stroh formalism for elastic surface waves of general profile
Authors: Parker D. F.
Published: September 2013

The Stroh formalism is widely used in the study of surface waves on anisotropic elastic half-spaces, to analyse existence and for calculating the resultant wave speed. Normally, the formalism treats complex exponential solutions. However, since waves are non-dispersive, a generalization to waves having general waveform exists and is here found by various techniques. Fourier superposition yields a description in which displacements are expressed in terms of three copies of a single pair of conjugate harmonic functions. An equivalent representation involving just one analytic function also is deduced. Both these show that at the traction-free boundary just one component (typically the normal component) of displacement may be specified arbitrarily, the others then being specific combinations of it and its Hilbert transform. The algebra is closely related to that used for complex exponential waves, although the surface impedance matrix is replaced by a transfer matrix, which better embodies the scale invariance properties of the waves. Using the scale-invariance property of the boundary-value problem, a further derivation is presented in terms of real quantities.
Two-dimensional molecular magnets with weak topological invariant magnetic moments: mathematical prediction of targets for chemical synthesis
Authors: Packwood D. M. , Reaves K. T. , Federici F. L. , Katzgraber H. G. , Teizer W.
Published: September 2013

An open problem in applied mathematics is to predict interesting molecules that are realistic targets for chemical synthesis. In this paper, we use a spin Hamiltonian-type model to predict molecular magnets (MMs) with magnetic moments that are intrinsically robust under random shape deformations to the molecule. Using the concept of convergence in probability, we show that for MMs in which all spin centres lie in-plane and all spin centre interactions are ferromagnetic, the total spin of the molecule is a ‘weak topological invariant’ when the number of spin centres is sufficiently large. By weak topological invariant, we mean that the total spin of the molecule depends only upon the arrangement of spin centres in the molecule, and is unlikely to change under shape deformations to the molecule. Our calculations show that only between 20 and 50 spin centres are necessary for the total spin of these MMs to be a weak topological invariant. The robustness effect is particularly enhanced for two-dimensional ferromagnetic MMs that possess a small number of spin rings in the structure.
Fungal metabolic plasticity and sexual development mediate induced resistance to arthropod fungivory
Authors: Döll Katharina , Chatterjee Subhankar , Scheu Stefan , Karlovsky Petr , Rohlfs Marko
Published: September 2013

Prey organisms do not tolerate predator attack passively but react with a multitude of inducible defensive strategies. Although inducible defence strategies are well known in plants attacked by herbivorous insects, induced resistance of fungi against fungivorous animals is largely unknown. Resistance to fungivory is thought to be mediated by chemical properties of fungal tissue, i.e. by production of toxic secondary metabolites. However, whether fungi change their secondary metabolite composition to increase resistance against arthropod fungivory is unknown. We demonstrate that grazing by a soil arthropod,
Folsomia candida
, on the filamentous fungus
Aspergillus nidulans
induces a phenotype that repels future fungivores and retards fungivore growth. Arthropod-exposed colonies produced significantly higher amounts of toxic secondary metabolites and invested more in sexual reproduction relative to unchallenged fungi. Compared with vegetative tissue and asexual conidiospores, sexual fruiting bodies turned out to be highly resistant against fungivory in facultative sexual
A. nidulans
. This indicates that fungivore grazing triggers co-regulated allocation of resources to sexual reproduction and chemical defence in
A. nidulans
. Plastic investment in facultative sex and chemical defence may have evolved as a fungal strategy to escape from predation.
Sex-specific responses to sexual familiarity, and the role of olfaction inDrosophila
Authors: Tan Cedric K. W. , Løvlie Hanne , Greenway Elisabeth , Goodwin Stephen F. , Pizzari Tommaso , Wigby Stuart
Published: September 2013

Studies of mating preferences have largely neglected the potential effects of individuals encountering their previous mates (‘directly sexually familiar’), or new mates that share similarities to previous mates, e.g. from the same family and/or environment (‘phenotypically sexually familiar’). Here, we show that male and femaleDrosophila melanogasterrespond to the direct and phenotypic sexual familiarity of potential mates in fundamentally different ways. We exposed a single focal male or female to two potential partners. In the first experiment, one potential partner was novel (not previously encountered) and one was directly familiar (their previous mate); in the second experiment, one potential partner was novel (unrelated, and from a different environment from the previous mate) and one was phenotypically familiar (from the same family and rearing environment as the previous mate). We found that males preferentially courted novel females over directly or phenotypically familiar females. By contrast, females displayed a weak preference for directly and phenotypically familiar males over novel males. Sex-specific responses to the familiarity of potential mates were significantly weaker or absent inOrco1mutants, which lack a co-receptor essential for olfaction, indicating a role for olfactory cues in mate choice over novelty. Collectively, our results show that direct and phenotypic sexual familiarity is detected through olfactory cues and play an important role in sex-specific sexual behaviour.
Evidence for a receiver bias underlying female preference for a male mating pheromone in sea lamprey
Authors: Buchinger T. J. , Wang H. , Li W. , Johnson N. S.
Published: September 2013

Receiver bias models suggest that a male sexual signal became exaggerated to match a pre-existing sensory, perceptual or cognitive disposition of the female. Accordingly, these models predict that females of related taxa possessing the ancestral state of signalling evolved preference for the male trait in a non-sexual context. We postulated that female preference for the male-released bile alcohol mating pheromone, 3 keto petromyzonol sulfate (3kPZS), of the sea lamprey (
Petromyzon marinus
) evolved as a result of a receiver bias. In particular, we propose that migratory silver lamprey (
Ichthyomyzon unicuspis
), a basal member of the Petromyzontidae, evolved a preference for 3kPZS released by stream-resident larvae as a means of identifying productive habitat for offspring. Larval silver lamprey released 3kPZS at rates sufficient to be detected by migratory lampreys. Females responded to 3kPZS by exhibiting upstream movement behaviours relevant in a migratory context, but did not exhibit proximate behaviours important to mate search and spawning. Male silver lamprey did not release 3kPZS at rates sufficient to be detected by females in natural high-volume stream environments. We infer that female silver lamprey cue onto 3kPZS excreted by stream-resident larvae as a mechanism to locate habitat conducive to offspring survival and that males do not signal with 3kPZS. We suggest that this female preference for a male signal in a non-sexual context represents a bias leading to the sexual signalling observed in sea lamprey.
The Reduction of Over Tip Leakage Loss in Unshrouded Axial Turbines Using Winglets and Squealers
Authors: Schabowski Zbigniew , Hodson Howard
Published: September 2013

The possibilities of reducing the over tip leakage loss of unshrouded rotors have been investigated using a linear cascade of turbine blades and computational fluid dynamics (CFD). The large-scale blade profile is the same as that of the tip profile of a low-speed high-pressure research turbine facility. The impact of various combinations of squealer and winglet geometries on the turbine performance has been investigated. The influence of the thickness of the squealers has also been assessed. It was found that a 22% reduction in loss slope was possible, when compared to the flat tip blade, using simple tip modifications. The results obtained with the suction side squealer and cavity tip agreed well with the work of other researchers. Three winglet-based tip geometries were tested. One was a plain winglet, the other two had squealers applied. A significant impact of the squealers and their shape on the tip gap flow pattern and loss generation was found. The physical processes occurring within the tip gap region for the tested geometries are explained using both numerical and experimental results. The impact of the flow pattern within the tip gap on the loss generation is described. Good agreement between CFD and the experimental data was found. This shows that CFD can be used with confidence in the design process of shroudless turbines.
Inverse Design of 3D Multistage Transonic Fans at Dual Operating Points
Authors: Page James H. , Hield Paul , Tucker Paul G.
Published: September 2013

Semi-inverse design is the automatic recambering of an aerofoil during a computational fluid dynamics (CFD) calculation in order to achieve a target lift distribution while maintaining thickness, hence, “semi-inverse.” In this design method, the streamwise distribution of curvature is replaced by a streamwise distribution of lift. The authors have developed an inverse design code based on the method of Hield (2008, “Semi-Inverse Design Applied to an Eight Stage Transonic Axial Flow Compressor,” ASME Paper No. GT2008-50430), which can rapidly design three-dimensional fan blades in a multistage environment. The algorithm uses an inner loop to design to radially varying target lift distributions, an outer loop to achieve radial distributions of stage pressure ratio and exit flow angle, and a choked nozzle to set design mass flow. The code is easily wrapped around any CFD solver. In this paper, we describe a novel algorithm for designing simultaneously for specified performance at full speed and peak efficiency at part speed, without trade-offs between the targets at each of the two operating points. We also introduce a novel adaptive target lift distribution, which automatically develops discontinuous changes of calculated magnitude, based on the passage shock, eliminating erroneous lift demands in the shock vicinity and maintaining a smooth aerofoil.
Inverse Aeroacoustic Design of Axial Fans Using Genetic Optimization and the Lattice-Boltzmann Method
Authors: Stadler Michael , Schmitz Michael B. , Laufer Wolfgang , Ragg Peter
Published: September 2013

The noise emitted by axial fans plays an integral role in product design. When conventional design procedures are applied, the aeroacoustic properties are controlled via an extensive trial-and-error process. This involves building physical prototypes and performing acoustic measurements. In general, this procedure makes it difficult for a designer to gain an understanding of the functional relationship between the noise and geometrical parameters of the fan. Hence, it is difficult for a human designer to control the aeroacoustic properties of the fan. To reduce the complexity of this process, we propose an inverse design methodology driven by a genetic algorithm. It aims to find the fan geometry for a set of given objectives. These include, most notably, the sound pressure frequency spectrum, aerodynamic efficiency, and pressure head. Individual bands of the sound pressure frequency spectrum may be controlled implicitly as a function of certain geometric parameters of the fan. In keeping with inverse design theory, we represent the design of axial fans as a multi-objective multiparameter optimization problem. The individual geometric components of the fan (e.g., rotor blades, winglets, guide vanes, shroud, and diffusor) are represented by free-form surfaces. In particular, each blade of the fan is individually parameterized. Hence, the resulting fan is composed of geometrically different blades. This approach is useful when studying noise reduction. For the analysis of the flow field and associated objectives, we utilize a standard Reynolds averaged Navier–Stokes (RANS) solver. However, for the evaluation of the generated noise, a meshless lattice-Boltzmann solver is employed. The method is demonstrated for a small axial fan, for which tonal noise is reduced.
Impact of Measurement Uncertainty in the Characteristic Maps of a Turbocharger on Engine Performance
Authors: Mai Holger , Vogt Mathias , Baar Roland , Kinski Andreas
Published: September 2013

The main goal of current engine development is to increase power density and efficiency and to minimize engine emissions. The idea is to obtain the desired power output with a highly charged combustion engine in combination with exhaust gas turbocharging and a very small engine displacement, which is known as downsizing. The selection of a turbocharger is based on the maps of the turbine and compressor, which are usually measured on a test bench. They also provide important boundary conditions on the engine process simulation of a supercharged engine with this turbocharger. In general, a very accurate measurement of the characteristic maps is desired to ensure the best possible matching. However, random and systematic errors have an impact on the measurement results. In order to assess the quality of the measured and calculated values, it is necessary to determine the uncertainties of the measurement variables as accurately as possible; particularly, the error propagation in calculating the efficiencies. The uncertainties are based on a systematic uncertainty component of the sensor and the confidence interval. In this way, the measurement uncertainty is estimated by linear and geometric combination of the calculated random and systematic uncertainties. After that, the respective uncertainty contributions and the identification of the relevant parameters that influence the resulting measurement uncertainty are evaluated. Knowing the measurement uncertainties of the characteristic maps of a turbocharger, the influence on engine operation will be determined with a one-dimensional engine process simulation model. Consequently, the determined measurement uncertainty will be applied as a deviation on the efficiencies and will be investigated in a GT POWER simulation. The impact of the measurement uncertainty on the engine performance is shown on the basis of load steps.
Modeling of Thin-Film Single and Multilayer Nanosecond Pulsed Laser Processing
Authors: Lutey Adrian H. A.
Published: September 2013

A complete model of nanosecond pulsed laser scribing of arbitrary thin multilayer structures is presented. The chain of events is separated according to time-scale; an initial simulation considers material response during the pulse; another combines this result with the much slower effects of heat flow away from the laser axis. The former considers heating, vaporization and phase explosion of metals in the course of a single pulse, accounting for variations in thermal conductivity and optical absorption as the material becomes superheated and approaches its critical temperature. The latter calculates the bidimensional heat flow in a complete multilayer structure over the course of a scribing operation, combining material properties and considering removal by both short-pulse ablation and long-term heating of the work piece. Simulation results for the single pulse ablation of an aluminum target align well with published experimental data both in terms of phase-explosion threshold and ablation depth as a function of fluence. Bidimensional heat flow simulations of a polypropylene–aluminum–polypropylene triplex structure reveal the progression of events toward steady state behavior; aluminum ejected due to short-pulse ablation and plastic removed due to conduction.
Strain Rate and Loading Waveform Effects on an Energy-Based Fatigue Life Prediction for AL6061-T6
Authors: Letcher Todd , Shen M.-H. H. , Scott-Emuakpor Onome , George Tommy , Cross Charles
Published: September 2013

The energy-based lifing method is based on the theory that the cumulative energy in all hysteresis loops of a specimens' lifetime is equal to the energy in a monotonic tension test. Based on this theory, fatigue life can be calculated by dividing monotonic strain energy by a hysteresis energy model, which is a function of stress amplitude. Recent studies have focused on developing this method for a sine wave loading pattern—a variable strain rate. In order to remove the effects of a variable strain rate throughout the fatigue cycle, a constant strain rate triangle wave loading pattern was tested. The testing was conducted at various frequencies to evaluate the effects of multiple constant strain rates. Hysteresis loops created with sine wave loading and triangle loading were compared. The effects of variable and constant strain rate loading patterns on hysteresis loops throughout a specimens' fatigue life are examined.
Domestic Hot Water Storage Tank: Design and Analysis for Improving Thermal Stratification
Authors: Devore Nathan , Yip Henry , Rhee Jinny
Published: September 2013

Experimental designs for a solar domestic hot water storage system were built in efforts to maximize thermal stratification within the tank. A stratified thermal store has been shown by prior literature to maximize temperature of the hot water drawn from the tank and simultaneously minimize collector inlet temperature required for effective heat transfer from the solar panels, thereby improving the annual performance of domestic solar hot water heating systems (DSHWH) by 30–60%. Our design incorporates partitions, thermal diodes, and a coiled heat exchanger enclosed in an annulus. The thermal diodes are passive devices that promote natural convection currents of hot water upward, while inhibiting reverse flow and mixing. Several variations of heat exchanger coils, diodes and partitions were simulated using ansys Computational Fluid Dynamics, and benchmarked using experimental data. The results revealed that the optimum design incorporated two partitions separated by a specific distance with four diodes for each partition. In addition, it was discovered that varying the length and diameter of the thermal diodes greatly affected the temperature distribution. The thermal diodes and partitions were used to maintain stratification for long periods of time by facilitating natural convective currents and taking advantage of the buoyancy effect. The results of the experiment and simulations proved that incorporating these elements into the design can greatly improve the thermal performance and temperature stratification of a domestic hot water storage tank.
Effects of Microhydrophobic Porous Layer on Water Distribution in Polymer Electrolyte Membrane Fuel Cells
Authors: Ahmadi Farzad , Roshandel Ramin
Published: September 2013

Performance of polymer electrolyte membrane fuel cells (PEMFC) at high current densities is limited to transport reactants and products. Furthermore, large amounts of water are generated and may be condensed due to the low temperature of the PEMFC. Development of a two-phase flow model is necessary in order to predict water flooding and its effects on the PEMFC performance. In this paper, a multiphase mixture model (M2) is used, accurately, to model two-phase transport in porous media of a PEMFC. The cathode side, which includes channel, gas diffusion layer (GDL), microporous layer (MPL), and catalyst layer (CL), is considered as the computational domain. A multidomain approach has been used and transport equations are solved in each domain independently with appropriate boundary conditions between GDL and MPL. Distributions of species concentration, temperature, and velocity field are obtained, and the effects of MPL on species distribution and fuel cell performance are investigated. MPL causes a saturation jump and a discontinuity in oxygen concentration at the GDL/MPL interface. The effect of MPL thickness on fuel cell performance is also studied. The results revealed that the MPL can highly increase the maximum power of a PEMFC.
Effect of Membrane Electrode Assembly Bonding Technique on Fuel Cell Performance and Platinum Crystallite Size
Authors: Buelte Steven , Walczyk Daniel , Sweeney Ian
Published: September 2013

Major efforts are underway to reduce fuel cell manufacturing costs, thereby facilitating widespread adoption of fuel cell technology in emerging applications, such as combined heat and power and transportation. This research investigates new methods for fabricating membrane electrode assemblies (MEAs), which are at the core of fuel cell technology. A key manufacturing step in the production of fuel cell MEAs is bonding two electrodes to an ionically conductive membrane. In particular, new MEA bonding methods are examined for polybenzimidazole-based phosphoric acid (PBI/PA) fuel cells. Two new methods of bonding PBI/PA fuel cell MEAs were studied with the goal of reducing cycle time to reduce manufacturing costs. Specifically, the methods included ultrasonic bonding and thermally bonding with advance process control (APC thermal). The traditional method of thermally bonding PBI MEAs requires 30 seconds, whereas the new bonding methods reduce the cycle time to 2 and 8 seconds, respectively. Ultrasonic bonding was also shown to significantly reduce the energy consumed by the bonding process. Adverse effects of the new bonding methods on cell performance and structure were not observed. Average cell voltages at 0.2 A/cm2 for ultrasonic, APC thermal, and thermally bonded MEAs were 650 mV, 651 mV, and 641 mV, respectively. The platinum crystallite size was found to be the same before and after ultrasonic bonding using XRD. Furthermore, changes in the electrode pore structure were not observed in SEM images taken after ultrasonic bonding. The test results show that it is possible to reduce manufacturing costs by switching to faster methods of bonding PBI phosphoric acid fuel cell MEAs.
Organic Inhibitors of the Anode Self-Corrosion in Aluminum-Air Batteries
Authors: Brito P. S. D. , Sequeira C. A. C.
Published: September 2013

Aluminum-air cells are very attractive systems due to their energy performance, namely their high energy density. Aluminum is a cheap and light material with a very high electropositive electrode potential, but a critical problem is its easy anodic oxidation in aqueous electrolytes complemented by hydrogen discharge. The purpose of this work was to study the electrochemical behavior of aluminum in strong alkaline medium in the presence of water-soluble organic compounds, such as carboxylic acids, amines, and amino acids in the perspective of self-corrosion control. The study was based on determinations of the amount of hydrogen released under potentiostatic polarization with separation of partial anodic and cathodic components. The effect of hydroxyl ion concentration and temperature on the electrochemical behavior of aluminum-water system was also analyzed. From the group of organic substances tested, the majority of them showed a significant inhibitory effect—given the high rate of self-corrosion of aluminum in these environments—especially the following: metacrylaminopropyl-trimethylammonium chloride (10.0 g/l) with an inhibitor efficiency of 69%; trimethylammonium chloride (10.0 g/l), with 67% efficiency; glycine (10.0 g/l) with 56% efficiency; alanine (10.9 g/l) with 40% efficiency; citric acid (10.0 g/l) with 38% efficiency; and tartaric acid (10.0 g/l) with 35% efficiency.
Antimony-assisted carbonization of Si(111) with solid source molecular beam epitaxy
Authors: Hackley Justin , Sarney Wendy L. , Richardson Christopher J. K.
Published: September 2013

The carbonization of an antimony-terminated Si (111) surface in a solid source molecular beam epitaxy system is presented. Reflection high-energy electron diffraction, atomic force microscopy, x-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy are used to characterize samples grown with and without antimony termination. It is shown that the antimony-terminated surface promotes the formation of thin, smooth and continuous SiC films at a relatively low temperature of 800 °C.
A novel method for routine quality assurance of volumetric‐modulated arc therapy
Authors: Wang Qingxin , Dai Jianrong , Zhang Ke
Published: September 2013

Purpose:

Volumetric‐modulated arc therapy (VMAT) is delivered through synchronized variation of gantry angle, dose rate, and multileaf collimator (MLC) leaf positions. The delivery dynamic nature challenges the parameter setting accuracy of linac control system. The purpose of this study was to develop a novel method for routine quality assurance (QA) of VMAT linacs.

Methods:

ArcCheck is a detector array with diodes distributing in spiral pattern on cylindrical surface. Utilizing its features, a QA plan was designed to strictly test all varying parameters during VMAT delivery on an Elekta Synergy linac. In this plan, there are 24 control points. The gantry rotates clockwise from 181° to 179°. The dose rate, gantry speed, and MLC positions cover their ranges commonly used in clinic. The two borders of MLC‐shaped field seat over two columns of diodes of ArcCheck when the gantry rotates to the angle specified by each control point. The ratio of dose rate between each of these diodes and the diode closest to the field center is a certain value and sensitive to the MLC positioning error of the leaf crossing the diode. Consequently, the positioning error can be determined by the ratio with the help of a relationship curve. The time when the gantry reaches the angle specified by each control point can be acquired from the virtual inclinometer that is a feature of ArcCheck. The gantry speed between two consecutive control points is then calculated. The aforementioned dose rate is calculated from an acm file that is generated during ArcCheck measurements. This file stores the data measured by each detector in 50 ms updates with each update in a separate row. A computer program was written in MATLAB language to process the data. The program output included MLC positioning errors and the dose rate at each control point as well as the gantry speed between control points. To evaluate this method, this plan was delivered for four consecutive weeks. The actual dose rate and gantry speed were compared with the QA plan specified. Additionally, leaf positioning errors were intentionally introduced to investigate the sensitivity of this method.

Results:

The relationship curves were established for detecting MLC positioning errors during VMAT delivery. For four consecutive weeks measured, 98.4%, 94.9%, 89.2%, and 91.0% of the leaf positioning errors were within ±0.5 mm, respectively. For the intentionally introduced leaf positioning systematic errors of −0.5 and +1 mm, the detected leaf positioning errors of 20 Y1 leaf were −0.48 ± 0.14 and 1.02 ± 0.26 mm, respectively. The actual gantry speed and dose rate closely followed the values specified in the VMAT QA plan.

Conclusions:

This method can assess the accuracy of MLC positions and the dose rate at each control point as well as the gantry speed between control points at the same time. It is efficient and suitable for routine quality assurance of VMAT.
What Lies Beneath: Looking Beyond Tumor Genetics Shows the Complexity of Signaling Networks Underlying Drug Sensitivity
Authors: Quaranta Vito , Tyson Darren R.
Published: September 2013

Two studies show the power of systems biology methods to improve cancer drug development and treatment strategy.
Focus Issue: Networking Cancer Treatment Strategies
Authors: Ferrarelli Leslie K.
Published: September 2013

Using network-level activity markers in cancer cells to predict sensitivity to kinase inhibitors may improve treatment strategy and clinical efficacy.
Alarm Bells
Authors: Pickersgill Helen
Published: September 2013

The cytosolic DNA sensor cyclic guanosine monophosphate–adenosine monophosphate synthase is essential for antiviral immunity in vivo.
Promoting Metastasis with Ubiquitin
Authors: Ferrarelli Leslie K.
Published: September 2013

A ubiquitin ligase enhances TGF-β receptor signaling to promote metastasis of breast cancer.
Comment on “Community-Wide Isoniazid Preventive Therapy Drives Drug-Resistant Tuberculosis: A Model-Based Analysis”
Authors: Ukwaja Kingsley N.
Published: September 2013

Mills
et al.
recently used mathematical modeling to show that community-wide isoniazid preventative therapy may lead to a long-term increase in resistance at the population level. Although community-wide isoniazid preventive therapy may be useful in preventing tuberculosis (TB) in low-TB/HIV settings, isoniazid resistance is especially of concern in high TB/HIV populations.
Exercise, Red Wine, or Both?
Authors: Bytautiene Egle
Published: September 2013

Exercise, not resveratrol, enhances skeletal muscle function in aging mice.
Gut Pathogens: Freeloading Dinner Guests?
Authors: Sheth Anandi N.
Published: September 2013

Increased gut carbohydrate availability due to antibiotic-induced effects on gut microflora allows for growth of pathogenic bacteria in a mouse model.
Less Is More: Burkholderia pseudomallei and Chronic Melioidosis
Authors: Nandi Tannistha , Tan Patrick
Published: September 2013

The Gram-negative bacterium
Burkholderia pseudomallei
is the causative agent of melioidosis, a serious infectious disease of humans and animals. Once considered an esoteric tropical disease confined to Southeast Asia and northern Australia, research on
B. pseudomallei
has recently gained global prominence due to its classification as a potential bioterrorism agent by countries such as the United States and also by increasing numbers of case reports from regions where it is not endemic. An environmental bacterium typically found in soil and water, assessing the true global prevalence of melioidosis is challenged by the fact that clinical symptoms associated with
B. pseudomallei
infection are extremely varied and may be confused with diverse conditions such as lung cancer, tuberculosis, or
Staphyloccocus aureus
infection. These diagnostic challenges, coupled with lack of awareness among clinicians, have likely contributed to underdiagnosis and the high mortality rate of melioidosis, as initial treatment is often either inappropriate or delayed. Even after antibiotic treatment, relapses are frequent, and after resolution of acute symptoms, chronic melioidosis can also occur, and the symptoms can persist for months to years. In a recent article, Price et al. [mBio 4(4):e00388-13, 2013, doi:10.1128/mBio.00388-13] demonstrate how comparative genomic sequencing can reveal the repertoire of genetic changes incurred by
B. pseudomallei
during chronic human infection. Their results have significant clinical ramifications and highlight
B. pseudomallei
’s ability to survive in a wide range of potential niches within hosts, through the acquisition of genetic adaptations that optimize fitness and resource utilization.
THE NOISY EXPECTATION–MAXIMIZATION ALGORITHM
Authors: OSOBA OSONDE , MITAIM SANYA , KOSKO BART
Published: September 2013

We present a noise-injected version of the expectation–maximization (EM) algorithm: the noisy expectation–maximization (NEM) algorithm. The NEM algorithm uses noise to speed up the convergence of the EM algorithm. The NEM theorem shows that additive noise speeds up the average convergence of the EM algorithm to a local maximum of the likelihood surface if a positivity condition holds. Corollary results give special cases when noise improves the EM algorithm. We demonstrate these noise benefits on EM algorithms for three data models: the Gaussian mixture model (GMM), the Cauchy mixture model (CMM), and the censored log-convex gamma model. The NEM positivity condition simplifies to a quadratic inequality in the GMM and CMM cases. A final theorem shows that the noise benefit for independent identically distributed additive noise decreases with sample size in mixture models. This theorem implies that the noise benefit is most pronounced if the data is sparse.
Third-order NLO property of beryllium-pyridyne complexes
Authors: Hatua Kaushik , Nandi Prasanta K.
Published: September 2013

Six pyridyne isomers and their complexes with beryllium have been considered for the theoretical study of the third-order polarizability. The NLO properties are calculated by employing the DFT functionals BLYP, B3LYP, BHHLYP, B3PW91, BP86 and B2PLYP for the 6-311++G(d,p) basis set. The C - Be bond length in the complexes varies within 1.644 Å–1.771 Å indicating covalent interactions between the metal and pyridynes. The present investigation reveals that the magnitude of second-hyperpolarizability of pyridynes strongly enhances upon complex formation with beryllium. The maximum hyperpolarizability has been predicted for the 2,5-diberyllium pyridine complex. The lowest value of hyperpolarizability is obtained for the 2,3- and 3,4-diberyllium pyridine complexes. The chosen DFT methods predict almost identical pattern of variation of NLO property. The variation of second-hyperpolarizability has been satisfactorily explained by the excitation energy and transition dipole moment associated with the most dominant excited state.
PERFORMANCE INVESTIGATION OF ADSORPTION–COMPRESSION HYBRID REFRIGERATION SYSTEMS
Authors: UDDIN KUTUB , MIYAZAKI TAKAHIKO , KOYAMA SHIGERU , SAHA BIDYUT BARAN
Published: September 2013

An analytical investigation on the performance of adsorption–compression hybrid refrigeration systems with two different cycle configurations, cascade type and subcool type has been performed. In the former type, a cascade condenser is used which works as a condenser for mechanical compression cycle and evaporator for adsorption cycle. In the latter type, an evaporative subcooler is used which subcool the fluid of mechanical compression cycle. The refrigerants examined for the mechanical compression cycle are R134a, R152a, R1234yf and R1234ze whereas ethanol is the refrigerant for the adsorption cycle. The main feature of the proposed system is the capability to significantly reduce work input for the mechanical compressor which results up to 30% energy saving potential depending on the selection of refrigerant and system configuration. Based on the thermodynamic properties and laws the study analyzed the effect of the major design parameters such as evaporation temperature, compressor discharge pressure and desorption temperature on the system performances.