bluuebunny/crossref_metadata_2025 huggingface dataset:
The Mechanisms of Noise Generation in a Compressor Model
Authors: Hulse B. T. , Large J. B.
Published: March 2013

A study is being undertaken in order to gain a better understanding of how compressor noise is produced. To facilitate mathematical analysis, the noise-generating mechanisms of axial-flow compressor blades have been investigated using flat blades. Analytical expressions are given for calculating the compressor noise due to blade thickness, loading, and vortex shedding. Measured values of compressor noise show good agreement with analytical predictions. It has been found that the lift, or loading noise, dominates the blade thickness noise. Rotor-stator spacing is an important parameter in rotor noise generation.
Design and Performance Characteristics of Over-Running Clutches in Gas Turbine Drive Applications
Authors: Daniels R. L.
Published: March 2013

Ever since the advent of the gas turbine engine, and its subsequent development and sophistication, the very unique operating requirements, characteristics, and benefits of gas turbine engines have challenged engineers of many disciplines to provide ancillary equipment and components that will function successfully with it. This paper will present selected specific examples of gas turbine drive system developments and their related power transmission designs with respect to clutch requirements—the Formsprag area of knowledge, know-how, and competence.
Influence of Microstructure and Heat-Treatment on Impact and Creep Properties of a Low Alloy CrMoV Turbine Steel
Authors: Relander K. , Geiger T.
Published: March 2013

This investigation concerns the strongly scattering mechanical properties of a 17 MoV 84 creep resistant steel. Emphasis is laid on the effect on microstructure of heat-treatment. The mechanical tests made after various austenitizing treatments, cooling rates, and tempering temperatures revealed that a complex relationship existed between the mechanical properties and microstructure in the steel precipitation hardened by vanadium carbides. In spite of constant tensile strength, the impact and creep properties in the steel therefore differ widely, due to relatively small microstructural effects. The study shows that the microstructural constituents, i.e., martensite, lower bainite, upper bainite in aciculare and globulare forms, as well as pre-eutectoid ferrite, all influence the room temperature ductility in a similar way to the creep ductility. However, in the case of creep strength, similar microstructural constituents have almost the reverse effect. As a result of these contrasting effects, it is not possible to obtain good ductility and creep properties at the same time. Any heat-treatments recommended can therefore only be a compromise between the properties desired.
Techniques Used in Achieving a High Specific Airflow for High-Output, Medium-Speed Diesel Engines
Authors: Pope J. A.
Published: March 2013

This paper discusses the factors which influence the airflow through the cylinder heads, and valves, on high-output, medium-speed diesel engines and the techniques used to achieve a high specific airflow. Descriptions of the methods used to flow test cylinder head ports are given, together with details of polynomial cam design. The results of some tests with a variable-timing camshaft, showing the effect of advance of exhaust-valve opening point, are included.
A Comparison of Theoretical and Experimental Results From Spherical Shells With a Single Radially Attached Nozzle
Authors: Witt F. J. , Gwaltney R. C. , Maxwell R. L. , Holland R. W.
Published: March 2013

A series of steel models having single nozzles radially and nonradially attached to a spherical shell is presently being examined by means of strain gages. Parameters being studied are nozzle dimensions, length of internal nozzle protrusions, and angles of attachment. The loads are internal pressure and axial thrust and moment loadings on the nozzle. This paper presents both experimental and theoretical results from six of the configurations having radially attached nozzles for which the sphere dimensions are equal and the outside diameter of the attached nozzle is constant. In some instances the nozzle protrudes through the vessel.
The Determination of Thermal Diffusivities of Thermal Energy Storage Materials, Part I: Solids up to Melting Point
Authors: Chang H. , Altman M. , Sharma R.
Published: March 2013

This paper describes a method for the determination of thermal diffusivities which has been developed specifically for substances which are poor conductors and which have high melting points. Materials which are useful for thermal energy storage fall into this category. The method has several unique features. The basic principle involved consists of raising the surface temperature of a solid specimen at a uniform rate. After the initial transients have died out, the diffusivity can be determined from temperature measurements alone. The advantages of the method are: (a) Heat flux measurements are not needed; (b) materials can be tested right up to the melting point, since the specimens can be encapsulated and softening can be tolerated; (c) large temperature ranges can be tested quickly; (d) precision and accuracy are good. The method has been extended to the liquid range, and results will be published as Part II. Results of measurements are reported for alumina and lithium fluoride. The results for alumina (Lucalox) check results reported previously. The results on LiF differ from published results. Data on other substances are still being produced and results will be published at a later date.
Investigations Concerning Flow Patterns Within the Impeller Channels of Radial-Inflow Turbines, With Some Reference to the Influence of the Splitter Vanes
Authors: Ariga Ichiro , Watanabe Ichiro , Fujie Kunio
Published: March 2013

The experimental results of the relative velocity distributions together with the static pressure distributions within the impeller channels of radial-inflow turbines with and without splitter vanes are presented. The flow patterns within three stream surfaces (blade-to-blade surfaces) having different passage depths are shown using two performance parameters, i.e., nondimensional weight flow and nondimensional rotation speed. The impellers used were of purely radial type or of two-dimensional type. Further, theoretical predictions for the relative velocity distributions within the impeller channels having no splitter vanes were conducted, and comparisons of the theoretical results with experimental data were made.
Coupling of Turbomachine Blade Vibrations Through the Rotor
Authors: Wagner J. T.
Published: March 2013

The forced vibration response of subsystems with different natural frequencies and damping, attached to a foundation with finite stiffness or mass, is calculated. Analytical models include simulations of turbomachine blading on a flexible disk or on a rotor with finite mass. Coupling through the disk or rotor explains variations in resonant frequencies and amplitudes that have been observed in blade-vibration tests. Effects on damping measurements are also determined.
Field Observations of Transient Servopressures in Kaplan Turbines
Authors: Mittendorf G. H. , Verna J. R.
Published: March 2013

Transient load rejection data obtained from and applied to Kaplan turbines are presented. The dynamic response of the system was investigated and stabilized after blade servopressure analyses. The interrelationship between gate position, blade position, blade servopressure, draft-tube pressure, and speed is shown for Kaplan turbines and propeller turbines for different types of load rejections.
A Review of Slip Factors for Centrifugal Impellers
Authors: Wiesner F. J.
Published: March 2013

This paper contains a general review of the various methods which have been proposed for the estimation of basic slip factors for centrifugal impellers. As a result of this study, it is concluded that the classical method proposed by Busemann in 1929 is still the most generally applicable prediction for the basic slip factor of centrifugal impellers. The paper then presents a very simple empirical expression, which fits the Busemann results extremely well over the whole range of practical blade angles and number of blades up to a limiting inlet-to-outlet radius ratio for the impeller. An empirical correction factor is also proposed for conditions which exceed this limiting radius ratio. Tabular comparisons of slip factors, with test data (where available), are given for over 60 pump and compressor impellers which have been cited previously in the literature, and the author has added data for several more compressor stages from his own experience.
Self-Excited Vibration of a Hydraulic Turbine
Authors: Crawford C. C. , Ruud F. O.
Published: March 2013

Severe vibration of a hydraulic turbine was found to be self-excited. Vibration at the natural frequency when operating at synchronous speed produced self-sustaining whirl of the shaft. Gyroscopic action of the turbine runner caused the vibration to be self-excited. Admission of relatively small amounts of compressed air to the region between the headcover baffle plate and the crown of the runner stopped the vibration by preventing buildup of a rotating pressure field.
Computational Fluid Dynamics Guided Investigation for Reducing Emissions and Increasing Exergy of the Pyroscrubber in a Petcoke Calcining Facility
Authors: Lei Zhao , Ting Wang
Published: March 2013

A pyroscrubber is a device used in the petroleum coke calcining industry to oxidize the carbonaceous contents, including hydrocarbon volatiles of the exhaust gas from the calcination kiln, so as to recover energy to produce electricity and leave no more than small traces of unburned volatiles, solid carbon, ash, or emission (e.g., CO, NOx, and SOx) in the flue gas discharged. Motivated by the need to maximize the energy recovery and reduce the pollutant emission from the pyroscrubber, a 3D computational model is developed to simulate the combustion and thermal-flow phenomena inside a pyroscrubber to guide an investigation of the means to reduce emissions and increase exergy output for downstream power generation. Computational fluid dynamics model validation is achieved by comparing the baseline case results with the plant measurement data of the temperature at three different locations, high bay, middle of the chamber, and exit, as well as NOx emissions at the exit. The simulation results show that the specially designed high-bay wall structure generates a strong mixing zone, forcing combustion to happen at an earlier stage and helping to efficiently utilize the main chamber space. A well-balanced amount of excess air is favorable in generating more energy output and lowering NOx emissions. Incomplete combustion with substoichiometric air cuts NOx emissions, but leads to less total energy output, lowers gas temperature, and increases CO emissions. A multistage burning strategy is introduced and studied and results show that it successfully cuts emission without compromising energy (electricity power) output.
Simulation of Char Dust Combustion Inside a Pyroscrubber Downstream of a Petroleum Coke Calcining Kiln
Authors: Lei Zhao , Ting Wang
Published: March 2013

A pyroscrubber is a furnace used in the petroleum coke calcining industry to recover energy from the carbonaceous contents, including char dust and hydrocarbon volatiles of the exhaust gas from the calcination kiln. The combusted hot gases are used to generate steam and produce electricity, so it is important to optimize the pyroscrubber performance to produce high-grade combusted gases to generate steam but with minimal emissions. A previous study employed the locally-homogeneous flow (LHF) model to study the means to improve combustion efficiency and reduce emissions. In the LHF model, the interphase exchange rates of mass, momentum and energy are assumed to be infinitely fast, so the dispersed phase (char dust) can be simplified as the gas phase, and the complex two-phase flow is then treated as a single-phase flow. In this study, LHF model is replaced with a solid particle combustion model by incorporating both finite-rate heterogeneous and homogeneous combustion processes. Results reveal that the particle combustion model generates much higher local flame temperature (2200 K) than in LHF model (1800 K). All char particles are burned before or in the high-bay area. Total energy output of the case with particle combustion model is 92% of the LHF model. Furthermore, motivated by the potential energy saving from removing the air blower power supply, this study further investigates the possible benefit of running the pyroscrubber with the ventilation doors open. Three cases with different combinations of air injections and door opening have been studied. Results show that the gas flow is stably stratified with a large amount of the entrained cold air moving at the bottom of the chamber and the hot combusted gas moving through the top. With the bottom doors completely open, sufficient air can be drawn into the pyroscrubber without the need of blowing air in, but the combustion gases will be overcooled making this practice unfavorable from the energy saving point of view.
Optimal Tandem Configuration for Oscillating-Foils Hydrokinetic Turbine
Authors: Kinsey Thomas , Dumas Guy
Published: March 2013

A numerical investigation based on 2D URANS simulations is performed in order to seek an optimal spatial configuration for two oscillating foils within a hydrokinetic turbine. The objective of the study is to maximize the power extraction efficiency of the turbine. Tandem spatial configurations are considered because in such arrangement both hydrofoils are sharing the same flow window, which allows the turbine to reach higher efficiencies. The relative positioning of the downstream foil oscillating in the wake shed by the upstream hydrofoil is seen to be critical. Indeed, favorable interactions between the downstream foil and the wake vortices may lead to unexpectedly high power-extraction efficiencies (up to 64%), while unfavorable interactions may cause the downstream foil to contribute negatively to the total power extracted. A global phase shift parameter is introduced to characterize the tandem configuration. This parameter combines the inter-foil spacing and motion phase-shift into a single term. It is found useful to predict additional favorable configurations based on known results for cases with similar upstream-foil wake behavior. A comparison with experimental data is provided. Numerical predictions are seen to overpredict the power extraction performance in some cases. This is likely due to the broken 2D coherence of vortices in the 3D reality which affects the vortex-induced velocities and the subsequent foil-wake interactions.
A Guanosine-Centric Mechanism for RNA Chaperone Function
Authors: Grohman Jacob K. , Gorelick Robert J. , Lickwar Colin R. , Lieb Jason D. , Bower Brian D. , Znosko Brent M. , Weeks Kevin M.
Published: March 2013

Simply Folding

RNA chaperones simplify what would otherwise be complex and slow RNA folding events.

Grohman
et al.

(p.
190
, published online 7 March) show that the Moloney murine leukemia virus (MuLV) nucleocapsid (NC) protein, which chaperones MuLV RNA dimerization promotes MuLV RNA folding by binding to exposed guanosine bases and destabilizing strong guanosine interactions. With base-pairs being rendered roughly of the same energy, RNA assembly pathways are simplified, promoting proper folding.
Observing Atomic Collapse Resonances in Artificial Nuclei on Graphene
Authors: Wang Yang , Wong Dillon , Shytov Andrey V. , Brar Victor W. , Choi Sangkook , Wu Qiong , Tsai Hsin-Zon , Regan William , Zettl Alex , Kawakami Roland K. , Louie Steven G. , Levitov Leonid S. , Crommie Michael F.
Published: March 2013

Creating Unstable Atomic Orbitals

A hallmark of atomic Bohr orbitals is that they are stable; that is, time independent. However, for a very highly charged nucleus, the electrons must be described with the relativistic Dirac equation; the motion becomes time dependent, with electrons spiraling into the nucleus and coupling to positrons at large distances from the nucleus. In graphene, charge carriers are mass-less and described by the relativistic Dirac equation, and could also exhibit “atomic collapse” states.

Wang
et al.

(p.
734
, published online 7 March) created highly charged clusters of calcium dimers by atomic manipulation with a scanning tunneling microscope. The emergence of atomic-collapse resonances with increasing cluster size and charge was observed with scanning tunneling microscopy.
3D Reconstruction of the Source and Scale of Buried Young Flood Channels on Mars
Authors: Morgan Gareth A. , Campbell Bruce A. , Carter Lynn M. , Plaut Jeffrey J. , Phillips Roger J.
Published: March 2013

Seeing Below the Surface

Marte Vallis represents the largest of the young outflow channels on Mars. Thought to be the result of an ancient megaflood that occurred during a period that is otherwise known to be cold and dry, this channel system extends more than approximately 1000 kilometers in length and 100 kilometers in width. The channels' depths are unknown, however, because they have been covered by lava flows. By using the SHARAD radar sounder on the Mars Reconnaissance Orbiter,

Morgan
et al.

(p.
607
, published online 7 March) produced a three-dimensional reconstruction of the subsurface channels. The channels are twice as deep as previously thought and the floodwaters came from the Cerberus Fossae extensional fracture system.
The Brain Activity Map
Authors: Alivisatos A. Paul , Chun Miyoung , Church George M. , Deisseroth Karl , Donoghue John P. , Greenspan Ralph J. , McEuen Paul L. , Roukes Michael L. , Sejnowski Terrence J. , Weiss Paul S. , Yuste Rafael
Published: March 2013

Researchers propose building technologies to enable comprehensive mapping of neural circuit activity to understand brain function and disease.
Novel Human Gammapapillomavirus Species in a Nasal Swab
Authors: Phan Tung Gia , Vo Nguyen P. , Aronen Matti , Jartti Laura , Jartti Tuomas , Delwart Eric
Published: March 2013

A divergent human gammapapillomavirus (γ-HPV) genome in a nasal swab from an elderly Finnish patient with respiratory symptoms was genetically characterized. The L1 gene of HPV-Fin864 shared <70% nucleotide identity to other reported γ-HPV genomes, provisionally qualifying it as a new species in the
Gammapapillomavirus
genus.
Draft Genome Sequence of the Oxytetracycline-Producing Bacterium Streptomyces rimosus ATCC 10970
Authors: Pethick Florence E. , MacFadyen Alison C. , Tang Zhenyu , Sangal Vartul , Liu Tze-Tze , Chu Ju , Kosec Gregor , Petkovic Hrvoje , Guo Meijin , Kirby Ralph , Hoskisson Paul A. , Herron Paul R. , Hunter Iain S.
Published: March 2013

We report the draft genome of
Streptomyces rimosus
(ATCC 10970), a soil isolate that produces oxytetracycline, a commercially important and clinically useful antibiotic.
Whole-Genome Sequence of a Freshwater Aerobic Anoxygenic Phototroph,
Porphyrobacter
sp. Strain AAP82, Isolated from the Huguangyan Maar Lake in Southern China
Authors: Li Xiuling , Koblížek Michal , Feng Fuying , Li Yunxu , Jian Jichang , Zeng Yonghui
Published: March 2013

The
Porphyrobacter
genus (of the class
Alphaproteobacteria
) contains aerobic anoxygenic phototrophic species. Here we report a draft genome sequence of a freshwater bacterium,
Porphyrobacter
sp. strain AAP82. It contains a 38-kb-long photosynthesis gene cluster, but carbon-fixation genes are absent. The presence of respiratory enzymes, tricarboxylic acid (TCA) cycle, and the Entner-Doudoroff pathway demonstrates its aerobic photoorganotrophic character.
Genome Sequence of Staphylococcus pseudintermedius Strain E140, an ST71 European-Associated Methicillin-Resistant Isolate
Authors: Moodley Arshnee , Riley Matthew C. , Kania Stephen A. , Guardabassi Luca
Published: March 2013

We report the first genome sequence of the methicillin-resistant
Staphylococcus pseudintermedius
(MRSP) strain E140, isolated from a canine bite wound infection in Denmark. This strain represents the dominant clonal lineage associated with canine MRSP infections in Europe.
Complete Genome Sequence of Goose Tembusu Virus, Isolated from Jiangnan White Geese in Jiangsu, China
Authors: Han Kaikai , Huang Xinmei , Li Yin , Zhao Dongmin , Liu Yuzhuo , Zhou Xiaobo , You Yuan , Xie Xingxing
Published: March 2013

Avian tembusu virus (TMUV), which was first identified in eastern China, is an emerging virus causing serious economic losses in the Chinese poultry industry. Here, we report the complete genome sequence of goose tembusu virus strain JS804, isolated from Jiangnan white geese with severe neurological signs. The genome of JS804 is 10,990 nucleotides (nt) in length and contains a single open reading frame encoding a putative polyprotein of 3,425 amino acids. Research of the whole sequence of tembusu virus will help us to understand further the molecular and evolutionary characteristics and pathogenesis of this virus.
Complete Genome Sequence of a Canine-Origin H3N2 Feline Influenza Virus Isolated from Domestic Cats in South Korea
Authors: Park Seong-Jun , Kang Bo-Kyu , Jeoung Hye-Young , Moon Hyoung-Joon , Hong Minki , Na Woonseong , Park Bong-Kyun , Poo Haryoung , Kim Jeong-Ki , An Dong-Jun , Song Dae-Sub
Published: March 2013

A canine-origin Korean H3N2 feline influenza virus (FIV), A/feline/Korea/01/2010 (H3N2), was isolated in 2010 from a dead cat with severe respiratory disease. Here, we report the first complete genome sequence of this virus, containing 3′ and 5′ noncoding regions, which will help elucidate the molecular basis of the pathogenesis, transmission, and evolution of FIV.
Stiffened plates of rectangular industrial ducts
Authors: Thanga Tharani , Sivakumaran K.S. , Halabieh Bassam
Published: March 2013

This paper deals with the design of steel plate elements of rectangular industrial ducts. Because of the practical aspect ratios and the stiffener arrangements, such a plate element is often treated as a long plate (one way slab), fixed supported at the edges and subjected to transverse pressure. The design pressure and the deflection limit determine the plate thickness and the stiffener spacing. Current design practice considers the geometrical nonlinearity, however, uses the strength criterion of first yield. This investigation postulates that consideration of partial yielding of the plate may result in an economical design option, while meeting the serviceability criterion. The study is based on nonlinear finite element analyses of long plates subjected to increasing transverse pressure. Dimensionless parameters that characterize the behavior of such plates were identified and varied in a parametric study. Based on these analyses, design equations have been established for plate thickness and for stiffener spacing corresponding to three different scenarios namely; 0%, 16.5%, and 33% of through thickness partial yielding of the plate. Results show that allowing for 16.5% yielding results in 50% increase in stiffener spacing, at the expense of about 40% increase in deflections. Partially yielding plates can satisfy the serviceability limits states and can lead to economical stiffened plate systems for large rectangular industrial ducts.
Classifying forestland from model-generated tree species habitat suitability in the Western Ecoregion of Nova Scotia, Canada
Authors: Baah-Acheamfour Mark , Bourque Charles P.-A. , Meng Fan-Rui , Swift D. Edwin
Published: March 2013

Forestland classification is central to the sustainable management of forests. In this paper, we explore the possibility of classifying forestland from species–habitat–suitability indices and a hybrid classification of modeled data. Raster-based calculations of species–habitat–suitability were derived as a function of landscape-level descriptions of incident photosynthetically active radiation (PAR), soil water content (SWC), and growing degree-days (GDD) for southwestern Nova Scotia, Canada. PAR and SWC were both generated with the LanDSET model and GDD from thermal data captured with the space-borne MODIS sensor. We compared the distribution of predicted forestland types with the natural range of target species as found in the provincial permanent sample plots (PSPs). Reasonable agreement (≥50% accuracy) existed between some forestland types (e.g., red maple – white birch – red oak and balsam fir – red maple) and PSP-based assessments of species presence–absence. Agreement was noticeably lower for other forestland types, such as sugar maple – beech – yellow birch (<50% accuracy). This discrepancy is attributed to forest-forming factors not directly addressed by the model, e.g., forest succession, stand interventions, and disturbance. Their addition in the model could change the dynamics of tree-species preference in southwest Nova Scotia and is worth examining. True model inaccuracies accounted for about 0.3%–15.0% of the total reported error.
Molluscan cells in culture: primary cell cultures and cell lines
Authors: Yoshino T.P. , Bickham U. , Bayne C.J.
Published: March 2013

In vitro cell culture systems from molluscs have significantly contributed to our basic understanding of complex physiological processes occurring within or between tissue-specific cells, yielding information unattainable using intact animal models. In vitro cultures of neuronal cells from gastropods show how simplified cell models can inform our understanding of complex networks in intact organisms. Primary cell cultures from marine and freshwater bivalve and gastropod species are used as biomonitors for environmental contaminants, as models for gene transfer technologies, and for studies of innate immunity and neoplastic disease. Despite efforts to isolate proliferative cell lines from molluscs, the snail Biomphalaria glabrata (Say, 1818) embryonic (Bge) cell line is the only existing cell line originating from any molluscan species. Taking an organ systems approach, this review summarizes efforts to establish molluscan cell cultures and describes the varied applications of primary cell cultures in research. Because of the unique status of the Bge cell line, an account is presented of the establishment of this cell line, and of how these cells have contributed to our understanding of snail host – parasite interactions. Finally, we detail the difficulties commonly encountered in efforts to establish cell lines from molluscs and discuss how these difficulties might be overcome.
SYMMETRY BREAKING IN TOPOLOGICAL QUANTUM GRAVITY
Authors: MIELKE ECKEHARD W.
Published: March 2013

A SL (5, ℝ) gauge-invariant topological field theory of gravity and possible gauge unifications are considered in four-dimensions (4D). The problem of quantization is evaluated in the asymptotic safety scenario. "Minimal" BF type models for the high energy limit are physically not quite realistic, a tiny symmetry breaking is needed to recover standard Einsteinian gravity for the macroscopic metrical background with induced cosmological constant.
UNDERGROUND GRAVITATIONAL WAVE OBSERVATORIES: KAGRA AND ET
Authors: PUNTURO MICHELE , SOMIYA KENTARO
Published: March 2013

Future gravitational wave observatories will be realized underground in order to reduce external disturbances, such as seismic, Newtonian and environmental noises. The Japanese gravitational wave telescope KAGRA is under construction at the Kamioka site and the Einstein Telescope gravitational wave observatory is under study in Europe; the common aspects, the differences and the expected performances of these innovative machines are investigated.
THE ENTROPY OF AN ACOUSTIC BLACK HOLE IN BOSE–EINSTEIN CONDENSATES: TRANSVERSE MODES AS A CURE FOR DIVERGENCES
Authors: RINALDI MASSIMILIANO
Published: March 2013

We consider the entropy associated to the phonons generated via the Hawking mechanism in a sonic hole in a Bose–Einstein condensate (BEC). In a previous paper, we looked at the (1+1)-dimensional case both in the hydrodynamic limit and in the case when high-frequency dispersion is taken in account. Here, we extend the analysis, based on the 't Hooft brick wall model, by including transverse excitations. We show that they can cure the infrared divergence that appears in the (1+1)-dimensional case, by acting as an effective mass for the phonons. In the hydrodynamic limit, where high-frequency dispersion is neglected, the ultraviolet divergence remains. On the contrary, in the dispersive case the entropy not only is finite, but it is completely fixed by the geometric parameters of the system.
Supporting interaction through haptic feedback in automotive user interfaces
Authors: Kern Dagmar , Pfleging Bastian
Published: March 2013

The boundaries between 'the digital' and our everyday physical world are dissolving as we develop more physical ways of interacting with computing. This forum presents some of the topics discussed in the colorful multidisciplinary field of tangible and embodied interaction.

Eva Hornecker, Editor
Bridging the CEO credibility gap
Authors: Rosenberg Daniel
Published: March 2013

Evaluation and usability as a practice area has diversified its approaches, broadened the spectrum of UX issues if addresses, and extended its contribution into deeper levels of product-development decision making. This forum addresses conceptual, methodological, and professional issues that arise in the field's continuing effort to contribute robust information about users to product planning and design.

David Slegel and Susan Dray, Editors
A systematic approach to classify design-time global scheduling techniques
Authors: Kritikakou Angeliki , Catthoor Francky , Kelefouras Vasilios , Goutis Costas
Published: March 2013

The scheduling problem is an important partially solved topic related to a wide range of scientific fields. As it applies to design-time mapping on multiprocessing platforms emphasizing on ordering in time and assignment in place, significant improvements can be achieved. To support this improvement, this article presents a complete systematic classification of the existing scheduling techniques solving this problem in a (near-)optimal way. We show that the proposed approach covers any global scheduling technique, including also future ones. In our systematic classification a technique may belong to one primitive class or to a hybrid combination of such classes. In the latter case the technique is efficiently decomposed into more primitive components each one belonging to a specific class. The systematic classification assists in the in-depth understanding of the diverse classes of techniques which is essential for their further improvement. Their main characteristics and structure, their similarities and differences, and the interrelationships of the classes are conceived. In this way, our classification provides guidance for contributing in novel ways to the broad domain of global scheduling techniques.
Offline arabic handwritten text recognition
Authors: Parvez Mohammad Tanvir , Mahmoud Sabri A.
Published: March 2013

Research in offline Arabic handwriting recognition has increased considerably in the past few years. This is evident from the numerous research results published recently in major journals and conferences in the area of handwriting recognition. Features and classifications techniques utilized in recent research work have diversified noticeably compared to the past. Moreover, more efforts have been diverted, in last few years, to construct different databases for Arabic handwriting recognition. This article provides a comprehensive survey of recent developments in Arabic handwriting recognition. The article starts with a summary of the characteristics of Arabic text, followed by a general model for an Arabic text recognition system. Then the used databases for Arabic text recognition are discussed. Research works on preprocessing phase, like text representation, baseline detection, line, word, character, and subcharacter segmentation algorithms, are presented. Different feature extraction techniques used in Arabic handwriting recognition are identified and discussed. Different classification approaches, like HMM, ANN, SVM, k-NN, syntactical methods, etc., are discussed in the context of Arabic handwriting recognition. Works on Arabic lexicon construction and spell checking are presented in the postprocessing phase. Several summary tables of published research work are provided for used Arabic text databases and reported results on Arabic character, word, numerals, and text recognition. These tables summarize the features, classifiers, data, and reported recognition accuracy for each technique. Finally, we discuss some future research directions in Arabic handwriting recognition.
Guest column
Authors: Chung Kai-Min , Pass Rafael
Published: March 2013

We survey recent results on parallel repetition theorems for computationally-sound interactive proofs (a.k.a. interactive arguments).
Toward Cool C4Crops
Authors: Long Stephen P. , Spence Ashley K.
Published: March 2013

C4photosynthesis under optimal conditions enables higher-efficiency use of light, water, and nitrogen than the C3form used by many crops. It is associated with the most productive terrestrial plants and crops but is largely limited to the tropics and subtropics. It has been argued that the C4photosynthetic apparatus is inherently limited to warm environments. A small group of C4species appear to have overcome this, and in contrast to the major C4crop, maize, these species are able to acclimate their photosynthetic apparatus to chilling conditions. This review explores the mechanisms underlying this difference as well as the potential of introducing these changes into maize and other warm-climate C4crops.
Christian Raetz: Scientist and Friend Extraordinaire
Authors: Dowhan William , Nikaido Hiroshi , Stubbe JoAnne , Kozarich John W. , Wickner William T. , Russell David W. , Garrett Teresa A. , Brozek Kathryn , Modrich Paul
Published: March 2013

Chris Raetz passed away on August 16, 2011, still at the height of his productive years. His seminal contributions to biomedical research were in the genetics, biochemistry, and structural biology of phospholipid and lipid A biosynthesis in Escherichia coli and other gram-negative bacteria. He defined the catalytic properties and structures of many of the enzymes responsible for the “Raetz pathway for lipid A biosynthesis.” His deep understanding of chemistry, coupled with knowledge of medicine, biochemistry, genetics, and structural biology, formed the underpinnings for his contributions to the lipid field. He displayed an intense passion for science and a broad interest that came from a strong commitment to curiosity-driven research, a commitment he imparted to his mentees and colleagues. What follows is a testament to both Chris's science and humanity from his friends and colleagues.
Cooperative Survey Research
Authors: Ansolabehere Stephen , Rivers Douglas
Published: March 2013

The rise of the Internet has radically altered survey research by changing how we think about sampling, driving down the cost of interviewing, and creating new ways of asking questions. This technology has also opened the way to a new style of cooperatively organized survey research. Projects such as the Cooperative Congressional Election Study (CCES) and the Cooperative Campaign Analysis Project (CCAP) involve collaborations of dozens of research teams that can collect very large samples and many smaller surveys tailored to the research questions of particular teams. This review examines the organization and key findings of these projects as well as their sampling methodology and its validity. Of particular importance, this article offers a direct comparison of the CCES with actual election results and the American National Election Studies (ANES), showing that the new survey approach yields highly accurate results that replicate the correlation structure of the ANES.
Green Clubs: Collective Action and Voluntary Environmental Programs
Authors: Potoski Matthew , Prakash Aseem
Published: March 2013

Voluntary environmental programs (VEPs) are institutions that encourage participating actors to produce environmental public goods beyond the requirements of government law. Drawing on the club approach to the study of VEPs, we identify four collective action challenges facing VEPs. First, sponsoring actors must be motivated to invest resources to create a VEP despite incentives to free ride on the efforts of others. Second, VEPs need to be designed to offer firms sufficient excludable incentives to join them. Third, VEPs need monitoring and enforcement mechanisms to ensure that participants adhere to program obligations and do not free ride on the efforts of other participants. Fourth, VEPs and their sponsors need to motivate stakeholders to compensate firms for producing environmental public goods. The literature reveals considerable variability in how these challenges are addressed, suggesting that successful VEPs need to fit their institutional contexts.
Constitutive expression of MMP9 in intestinal epithelium worsens murine acute colitis and is associated with increased levels of proinflammatory cytokine Kc
Authors: Liu Hongchun , Patel Neal R. , Walter Lewins , Ingersoll Sarah , Sitaraman Shanthi V. , Garg Pallavi
Published: March 2013

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease, is a chronic inflammatory disease associated with an increased risk for colon cancer. Matrix metalloproteinases (MMPs) are the predominant proteinases expressed in the gut mucosa during active IBD. Our laboratory has previously demonstrated that epithelial-derived MMP9 is absent in normal colonic tissue but is upregulated during IBD. In this study MMP9 transgenic mice (Tg-villin-MMP9) are generated specifically to overexpress MMP9 in intestinal epithelium to examine the role and underlying mechanism by which it modulates the pathogenesis of acute colitis. Dextran sodium sulfate (3% DSS)- and Salmonella typhimurium (S.T.)-induced colitis models were used to study gut inflammation in Tg-villin-MMP9 and wild-type littermates (WT). Colonic tissue was analyzed via Western blot, histology, myeloperoxidase (MPO) assay, and quantitative PCR. Tg-villin-MMP9 mice expressed significantly increased MMP9 mRNA and protein expression at basal level. There was a significant decrease in the goblet cells, but a significant increase in proliferation and apoptosis were observed among Tg-villin-MMP9 mice compared with WT mice. There was also a significant increase in the proinflammatory chemokine Kc among Tg-villin-MMP9 compared with WT mice. Tg-villin-MMP9 exhibited a severe inflammatory response than WT mice in both DSS- and S.T.-induced colitis models as evident by greater weight loss and higher clinical score, histological score, and MPO activity, which correlated with relative levels of Kc mRNA. MMP9 expressed by intestinal epithelial cells mediates inflammation in colitis with simultaneous increase in proinflammatory cytokine Kc.
Dihydrotestosterone is elevated following sprint exercise in healthy young men
Authors: Smith Alan A. , Toone Rebecca , Peacock Oliver , Drawer Scott , Stokes Keith A. , Cook Christian J.
Published: March 2013

Dihydrotestosterone (DHT) exerts both functional and signaling effects extending beyond the effects of testosterone in rodent skeletal muscle. As a primer for investigating the role of DHT in human skeletal muscle function, this study aimed to determine whether circulating DHT is acutely elevated in men following a bout of repeat sprint exercise and to establish the importance of training status and sprint performance to this response. Fourteen healthy active young men (V̇o2max61.0 ± 8.1 ml·kg body mass−1·min−1) performed a bout of repeat sprint cycle exercise at a target workload based on an incremental work-rate maximum (10 × 30 s at 150% Wmaxwith 90-s recovery). Venous blood samples were collected preexercise and 5 and 60 min after exercise. Five minutes after exercise, there were significant elevations in total testosterone (TT; P < 0.001), free testosterone (FT; P < 0.001), and DHT ( P = 0.004), which returned to baseline after 1 h. Changes in DHT with exercise (5 min postexercise − preexercise) correlated significantly with changes in TT ( r = 0.870; P < 0.001) and FT ( r = 0.914; P < 0.001). Sprinting cadence correlated with changes in FT ( r = 0.697; P = 0.006), DHT ( r = 0.625; P = 0.017), and TT ( r = 0.603; P = 0.022), and habitual training volume correlated with the change in TT ( r = 0.569, P = 0.034). In conclusion, our data demonstrate that DHT is acutely elevated following sprint cycle exercise and that this response is influenced by cycling cadence. The importance of DHT in the context of exercise training and sports performance remains to be determined.
Developing Safety Criteria for Introducing New Agents into Neoadjuvant Trials
Authors: DeMichele Angela , Berry Donald A. , Zujewski JoAnne , Hunsberger Sally , Rubinstein Larry , Tomaszewski Joseph E. , Kelloff Gary , Perlmutter Jane , Buxton Meredith , Lyandres Julia , Albain Kathy S. , Benz Chris , Jo Chien A. , Haluska Paul , Leyland-Jones Brian , Liu Minetta C. , Munster Pamela , Olopade Olufunmilayo , Park John W. , Parker Barbara A. , Pusztai Lajos , Tripathy Debu , Rugo Hope , Yee Douglas , Esserman Laura
Published: March 2013

New approaches to drug development are critically needed to lessen the time, cost, and resources necessary to identify and optimize active agents. Strategies to accelerate drug development include testing drugs earlier in the disease process, such as the neoadjuvant setting. The U.S. Food and Drug Administration (FDA) has issued guidance designed to accelerate drug approval through the use of neoadjuvant studies in which the surrogate short-term endpoint, pathologic response, can be used to identify active agents and shorten the time to approval of both efficacious drugs and biomarkers identifying patients most likely to respond. However, this approach has unique challenges. In particular, issues of patient safety are paramount, given the exposure of potentially curable patients to investigational agents with limited safety experience. Key components to safe drug development in the neoadjuvant setting include defining a study population at sufficiently poor prognosis with standard therapy to justify exposure to investigational agents, defining the extent and adequacy of safety data from phase I, detecting potentially harmful interactions between investigational and standard therapies, improving study designs, such as adaptive strategies, that limit patient exposure to ineffective agents, and intensifying safety monitoring in the course of the trial. The I-SPY2 trial is an example of a phase II neoadjuvant trial of novel agents for breast cancer in which these issues have been addressed, both in the design and conduct of the trial. These adaptations of phase II design enable acceleration of drug development by reducing time and cost to screen novel therapies for activity without compromising safety. Clin Cancer Res; 19(11); 2817–23. ©2013 AACR.
TYK2–STAT1–BCL2 Pathway Dependence in T-cell Acute Lymphoblastic Leukemia
Authors: Sanda Takaomi , Tyner Jeffrey W. , Gutierrez Alejandro , Ngo Vu N. , Glover Jason , Chang Bill H. , Yost Arla , Ma Wenxue , Fleischman Angela G. , Zhou Wenjun , Yang Yandan , Kleppe Maria , Ahn Yebin , Tatarek Jessica , Kelliher Michelle A. , Neuberg Donna S. , Levine Ross L. , Moriggl Richard , Müller Mathias , Gray Nathanael S. , Jamieson Catriona H.M. , Weng Andrew P. , Staudt Louis M. , Druker Brian J. , Look A. Thomas
Published: March 2013

Targeted molecular therapy has yielded remarkable outcomes in certain cancers, but specific therapeutic targets remain elusive for many others. As a result of two independent RNA interference (RNAi) screens, we identified pathway dependence on a member of the Janus-activated kinase (JAK) tyrosine kinase family, TYK2, and its downstream effector STAT1, in T-cell acute lymphoblastic leukemia (T-ALL). Gene knockdown experiments consistently showed TYK2 dependence in both T-ALL primary specimens and cell lines, and a small-molecule inhibitor of JAK activity induced T-ALL cell death. Activation of this TYK2–STAT1 pathway in T-ALL cell lines occurs by gain-of-function TYK2 mutations or activation of interleukin (IL)-10 receptor signaling, and this pathway mediates T-ALL cell survival through upregulation of the antiapoptotic protein BCL2. These findings indicate that in many T-ALL cases, the leukemic cells are dependent upon the TYK2–STAT1–BCL2 pathway for continued survival, supporting the development of molecular therapies targeting TYK2 and other components of this pathway.

Significance: In recent years, “pathway dependence” has been revealed in specific types of human cancer, which can be important because they pinpoint proteins that are particularly vulnerable to antitumor-targeted inhibition (so-called Achilles' heel proteins). Here, we use RNAi technology to identify a novel oncogenic pathway that involves aberrant activation of the TYK2 tyrosine kinase and its downstream substrate, STAT1, which ultimately promotes T-ALL cell survival through the upregulation of BCL2 expression. Cancer Discov; 3(5); 564–77. ©2013 AACR.

See related commentary by Fontan and Melnick, p. 494

This article is highlighted in the In This Issue feature, p. 471
Secreted Expression of a Hyperthermophilic α-Amylase Gene from Thermococcus sp. HJ21 in Bacillus subtilis
Authors: Ying Qi , Zhang Chong , Guo Fangfang , Wang Shujun , Bie Xiaomei , Lu Fengxia , Lu Zhaoxin
Published: March 2013

The hyperthermophilic α-amylase from Thermococcus sp. HJ21 possesses unique traits (Ca2+-independent thermostability and optimal temperature of 95°C) that make it a great potential candidate for use in the food industry. However, this Archaea isolated from a deep-sea thermal vent requires strict control of culture conditions and produces only small amounts of α-amylase. To solve these problems, the α-amylase gene was cloned and expressed in Bacillus subtilis, which is an ideal food-grade host for heterologous protein expression. To express high levels of this α-amylase in B. subtilis, the promoters Pgrac, PxylA, P43, and Phag were used to construct four different expression vectors for testing. The vector containing the PxylA promoter was found to have the highest transcriptional activity and produce the highest amylase activity (19.6 U/ml). To test the secretion efficiency of signal peptides in B. subtilis, three signal peptides were cloned and fused to the α-amylase gene (lacking its native signal peptide). The optimal signal peptide was SamyQ, with a secretion efficiency of approximately 90%. These results indicate that the promoter PxylA and signal peptide SamyQ tested in this study may be useful for the expression and secretion of archaeal proteins in B. subtilis.