bluuebunny/crossref_metadata_2025_split huggingface dataset:
The race for interferon‐free HCV therapies: a snapshot by the spring of 2012
Authors: De Clercq Erik 
Published: August 2012

SUMMARYAfter a decade of having been the standard of care (SOC) for the treatment of chronic HCV infection, PEGylated IFN (combined with ribavirin) is now at the verge of being complemented and then replaced by a combination of new DAAs and even some compounds interacting with host cell factors. Principal targets for the direct‐acting antivirals (DAAs) are the protease NS3/4A, the protein NS5A, and the RNA‐dependent RNA polymerase NS5B, which offers at least two target sites, the catalytic domain for nucleos(t)ides and several non‐catalytic (allosteric) domains for the non‐nucleoside type of NS5B inhibitors. Two PIs have already been approved, but many more NS3/4A, NS5A, and NS5B (up to 40!) inhibitors are in (pre)clinical development. The abundance of candidate anti‐HCV drugs will, on the one hand, speed up their development but, on the other hand, complicate the choice of the most appropriate drug combination(s). Copyright © 2012 John Wiley & Sons, Ltd.
Distributed control of nonlinear diffusion systems by input–output linearization
Authors: Maidi Ahmed , Corriou Jean‐Pierre 
Published: August 2012

SUMMARYThis paper addresses the distributed control by input–output linearization of a nonlinear diffusion equation that describes a particular but important class of distributed parameter systems. Both manipulated and controlled variables are assumed to be distributed in space. The control law is designed using the concept of characteristic index from geometric control by using directly the PDE model without any approximation or reduction. The main idea consists in the control design in assuming an equivalent linear diffusion equation obtained by use of the Cole–Hopf transformation. This framework helps to demonstrate the closed‐loop stability using some concepts from the powerful semigroup theory. The performance of the proposed controller is successfully tested, through simulation, by considering a nonlinear heat conduction problem concerning the control of the temperature of a steel plate modeled by a nonlinear heat equation with Dirichlet boundary conditions. Copyright © 2012 John Wiley & Sons, Ltd.
Cooperative control with distributed gain adaptation and connectivity estimation for directed networks
Authors: Qu Zhihua , Li Chaoyong , Lewis Frank 
Published: August 2012

SUMMARYThis paper addresses the problem of how to achieve superior performance by adaptively and distributively adjusting control gains of a cooperative control system. It is shown that according to distributed observations of changing network topologies and on the basis of online estimation of network connectivity, cooperative controls with adaptive gains can be synthesized to making the time derivative of the cooperative control Lyapunov function more negative and hence to improve stability and convergence of the overall system. For undirected networks, the proposed adaptive design reduces to improving the Fiedler eigenvalue (algebraic connectivity) as well as other eigenvalues. On the other hand, connectivity of a directed network is characterized by the property of the first left eigenvector(s) associated with its dominant eigenvalue, and in this paper, a distributed high‐gain observer design is proposed for each of the networked systems to utilize the same communication network among the systems. It is shown that even in the presence of transmission delays, the distributed estimators converge fast to the first left eigenvector(s) of the network. In addition, the expected consensus value(s) of the overall cooperative system under control is also estimated in a distributive manner. Rigorous analysis is carried out on estimation convergence and observer gain selection. It is shown that the proposed estimation and adaptive control designs are fully distributed, have guaranteed performance for all possible varying topologies as long as their dwelling times are bounded away from zero, and are robust with respect to excessively fast topology changes. Simulation results are included to demonstrate effectiveness of the proposed estimation and control schemes. Copyright © 2012 John Wiley & Sons, Ltd.
Constrained control Lyapunov function based model predictive control design
Authors: Mahmood Maaz , Mhaskar Prashant 
Published: August 2012

SUMMARYThis work considers linear systems with input constraints with the objective of designing a controller that guarantees stability from all initial conditions in the null‐controllable region (the set of initial conditions from where the system can be stabilized). To this end, a recently developed procedure for construction of constrained control Lyapunov functions is utilized within a Lyapunov‐based model predictive controller coupled with an auxiliary control design to achieve stabilization from all initial conditions in the null‐controllable region. Illustrative simulation results as well as an application to a nonlinear chemical process example is presented to demonstrate the efficacy of the results.Copyright © 2012 John Wiley & Sons, Ltd.
UNCERTAINTY IN PREDICTING THE FISH‐RESPONSE TO TWO‐DIMENSIONAL HABITAT MODELING USING FIELD DATA
Authors: Boavida I. , Santos J. M. , Katopodis C. , Ferreira M. T. , Pinheiro A. 
Published: August 2012

ABSTRACTBoth water managers and researchers have the same goal when it comes to fish conservation, namely, to sustain, to improve or to restore aquatic habitat. To this aim, two‐dimensional (2D) hydrodynamic models have been widely used in aquatic habitat studies because they simulate flow with high accuracy and can predict habitat dynamics. The River2D model is able to integrate the habitat suitability curves for fish life stages with the simulated depth and velocity fields and the riverbed characteristics of substrate and cover, thereby estimating the corresponding weighted usable area, and thus predicting the potential distribution of fish species in the river. However, little is known about the in situ variability associated with such predictions both for hydraulic and biological data, whereas ecological responses are known to be driven by variability. Moreover, when calculating habitat availability, differences can be found by considering in the weighted usable area formulation substrate or cover or even both. To test the level of predictive accuracy of hydraulic and biological simulations, we modelled the habitat use by two fish species, the Iberian barbel Luciobarbus bocagei and the Iberian straight‐mouth nase Pseudochondrostoma polylepis, according to their requirements for depth, velocity, substrate and cover and then compared measured and simulated hydraulic and biological outcomes using the River2D model. Results indicate that 2D simulation depends on data collection, especially the density and location of bed topography points. Substantial differences were found in the biological responses. Results may differ when choosing different habitat availability variables. Similarly, habitat use may also be influenced by other biotic and abiotic interactions occurring in ecosystems, and restoration planning should be aware of such variability. Copyright © 2012 John Wiley & Sons, Ltd.
STREAM HABITAT MODELLING FOR CONSERVING A THREATENED HEADWATER FISH IN THE UPPER CUMBERLAND RIVER, KENTUCKY
Authors: Liang L. , Fei S. , Ripy J. B. , Blandford B. L. , Grossardt T. 
Published: August 2012

ABSTRACTThe conservation of stream biodiversity requires more explicit knowledge on the distribution of aquatic species within the context of their specific environmental settings and stresses. Although species distribution models (SDMs) have been widely used for organisms occupying contiguous spatial extents, the implementation of SDMs in relatively complex and segmented riverine networks is still at its early stage. In this study, we explicitly modelled the headwater stream habitat for the threatened blackside dace (Phoxinus cumberlandensis) endemic to the upper Cumberland River, Kentucky, USA. An occurrence record data set, along with variables describing stream properties and land use impacts, was used to predict the fish habitat suitability at the stream segment level. An approach combining geographic information systems and the maximum entropy species distribution modelling (MaxEnt) was adopted. Results demonstrated that natural conditions and land use disturbances, respectively, form the primary and secondary environmental constraints on the species' habitat. We generated regional‐scale management‐friendly maps showing subwatershed habitat suitability and locations of the clustered suitable habitats (hotspots) and thus set an example for spatially explicit management of threatened and endangered riverine species. This study demonstrates the usefulness of SDMs for stream network–based environments in the facilitation of biogeographic conservation efforts and studies. Copyright © 2012 John Wiley & Sons, Ltd.
High‐Interstitial Stainless Austenitic Steel Castings
Authors: Berns Hans , Nabiran Nilofar , Mujica Laís 
Published: August 2012

AbstractInterstitial atoms are most effective in strengthening austenitic steels. In stainless grades, chromium strongly reduces the solubility limit of carbon. High‐nitrogen contents require costly pressure or powder metallurgy to dissolve N in the melt. The combination of both elements comes with a high‐interstitial solubility at normal pressure of air. Sand casting with 18 mass% Cr and Mn each and 0.85 mass% (C + N) were industrially produced. The investigation revealed: proof strength Rp0.2 = 457 [MPa], true fracture strength R = 1714 [MPa], fracture elongation A = 44%, notch impact toughness KV = 290 J combined with a DBTT of −94°C, an impact wear resistance comparable to Hadfield steel X120Mn12 but combined with a good corrosion resistance. Deep freezing and cold working does not effect the low relative magnetic permeability. This unique combination of properties offers advantages in application.
Effect of Heat Treatment on Microstructure and Mechanical Properties of 2.25Cr–1Mo Steel
Authors: Wang Wei , Zhao Wengui , Qu Jinbo 
Published: August 2012

AbstractThe effect of heat treatment on microstructure and mechanical properties of a ferritic heat‐resistant steel, 2.25Cr–1Mo, was investigated. The characteristics of carbides, i.e., size, morphology, distribution, and composition, in different stages of heat treatment were examined by using transmission electron microscopy (TEM) and energy dispersive X‐ray (EDX). As the heat treatment proceeded from normalizing and tempering (NT, the delivery state), simulated post‐welding heat treatment (PWHT), to step cooling (SC), the carbides evolved from M3C, Mo2C to M7C3, M23C6. The uniformly dispersed carbides, e.g., Mo2C, M7C3, and M23C6, are responsible for the excellent mechanical properties and creep resistance of the steel. The result demonstrates that the coarsening of carbides deteriorates impact toughness and the morphology, crystal structure, and chemical composition of carbides are also important influencing factors.
In Situ Observation of Surface Electrochemical Activities of Lean Duplex Stainless Steel LDX 2101
Authors: Li Xuyan , Guo Lifang , Han Dong , Li Jin , Jiang Yiming 
Published: August 2012

AbstractThe surface electrochemical corrosion activity of the economic lean duplex stainless steel LDX2101 was investigated in situ in chloride solution with a combination of long working distance microscope (LWDM) and electrochemical techniques. In addition, the site and chemical composition of the electrochemical active points on the specimen surface were also determined with integrated scanning electron microscope/energy dispersive X‐ray spectroscope (SEM/EDS) system. The results demonstrated that: (i) The reaction of α → Cr2N + γ2 precedes that of α → σ + γ2 when LDX2101 was aged at 700°C. (ii) The initiation sites of electrochemical active points could be determined by LWDM in combination with potentiostatic pulse technique (PPT). (iii) The sites of electrochemical active points were found to change from inclusions (MnS/Al2O3) to secondary austenite phase (γ2), with the increase of aging time at 700°C.
Viruses in Biology
Authors: López-García Purificación , Moreira David 
Published: August 2012

AbstractDuring the first half of the twentieth century, many scientists considered viruses the smallest living entities and primitive life forms somehow placed between the inert world and highly evolved cells. The development of molecular biology in the second half of the century showed that viruses are strict molecular parasites of cells, putting an end to previous virocentric debates that gave viruses a primeval role in the origin of life. Recent advances in comparative genomics and metagenomics have uncovered a vast viral diversity and have shown that viruses are active regulators of cell populations and that they can influence cell evolution by acting as vectors for gene transfer among cells. They have also fostered a revival of old virocentric ideas. These ideas are heterogeneous, extending from proposals that consider viruses functionally as living beings and/or as descendants of viral lineages that preceded cell evolution to other claims that consider viruses and/or some viral families a fourth domain of life. In this article, we revisit these virocentric ideas and analyze the place of viruses in biology in light of the long-standing dichotomic debate between metabolist and geneticist views which hold, respectively, that self-maintenance (metabolism) or self-replication and evolution are the primeval features of life. We argue that whereas the epistemological discussion about whether viruses are alive or not and whether some virus-like replicators precede the first cells is a matter of debate that can be understood within the metabolism-versus-genes dialectic; the claim that viruses form a fourth domain in the tree of life can be solidly refuted by proper molecular phylogenetic analyses and needs to be removed from this debate.
Contraceptive counseling in Turkey after induced abortion
Authors: Günyeli Ilker , Abike Faruk , Bingöl Banu , Ornek Turkan 
Published: August 2012

AbstractObjectiveTo determine the effectiveness of post‐abortion contraceptive counseling to women with unwanted pregnancy and to investigate use of modern contraceptive methods among Turkish women.MethodsA prospective case–control study was conducted at 3 Turkish centers between March 23, 2008, and January 10, 2011. A total of 333 women enrolled in the study were divided into 2 groups. Women in group 1 (n = 140) presented with unwanted pregnancy requiring induced abortion whereas women in group 2 (n = 193) had requested contraception counseling.ResultsThe use of coitus interruptus or condoms was significantly more frequent in group 1 than in group 2 (P < 0.001). No statistically significant differences were detected between the 2 groups in their use of oral contraceptives, intrauterine devices, injection methods, calendar methods, and other methods. The education level attained by women in group 1 was lower than that of women in group 2 (P = 0.041).ConclusionIncreased effort is required to ensure that sufficient education about family planning is provided to Turkish women for the prevention of unwanted pregnancies and induced abortions.
On the unique features of post‐disaster humanitarian logistics
Authors: Holguín‐Veras José , Jaller Miguel , Van Wassenhove Luk N. , Pérez Noel , Wachtendorf Tricia 
Published: August 2012

AbstractLogistic activity can be thought of as a socio‐technical process whereby a social network of individuals orchestrates a series of technical activities using supporting systems such as transportation and communications. To understand the functioning of the entire system requires proper consideration of all its components. We identify seven key components: the objectives being pursued, the origin of the commodity flows to be transported, knowledge of demand, the decision‐making structure, periodicity and volume of logistic activities, and the state of the social networks and supporting systems. Based on our analysis of the differences between commercial and humanitarian logistics, we pinpoint research gaps that need to be filled to enhance both the efficiency of humanitarian logistics and the realism of the mathematical models designed to support it.We argue that humanitarian logistics is too broad a field to fit neatly into a single definition of operational conditions. At one end of the spectrum we find humanitarian logistic efforts of the kind conducted in long‐term disaster recovery and humanitarian assistance, where operational efficiency – akin to commercial logistics – is a prime consideration. At the other, post‐disaster humanitarian logistic operations involved in disaster response and short‐term recovery activities represent a vastly different operational environment, often in chaotic settings where urgent needs, life‐or‐death decisions and scarce resources are the norm. The huge contrast between these operational environments requires that they be treated separately.
Rational weak mixing in infinite measure spaces
Authors: AARONSON JON 
Published: August 2012

AbstractRational weak mixing is a measure theoretic version of Krickeberg’s strong ratio mixing property for infinite measure preserving transformations. It requires ‘density’ ratio convergence for every pair of measurable sets in a dense hereditary ring. Rational weak mixing implies weak rational ergodicity and (spectral) weak mixing. It is enjoyed for example by Markov shifts with Orey’s strong ratio limit property. The power, subsequence version of the property is generic.
Measure-theoretic chaos
Authors: DOWNAROWICZ TOMASZ , LACROIX YVES 
Published: August 2012

AbstractWe define new isomorphism invariants for ergodic measure-preserving systems on standard probability spaces, called measure-theoretic chaos and measure-theoretic$^+$ chaos. These notions are analogs of the topological chaos DC2 and its slightly stronger version (which we denote by $\text {DC}1\frac 12$). We prove that: (1) if a topological system is measure-theoretically (measure-theoretically$^+$) chaotic with respect to at least one of its ergodic measures then it is topologically DC2 $(\text {DC}1\frac 12)$ chaotic; (2) every ergodic system with positive Kolmogorov–Sinai entropy is measure-theoretically$^+$ chaotic (even in a slightly stronger uniform sense). We provide an example showing that the latter statement cannot be reversed, that is, of a system of entropy zero with uniform measure-theoretic$^+$chaos.
High-speed granular chute flows
Authors: Holyoake Alex J. , McElwaine Jim N. 
Published: August 2012

AbstractThis paper reports experimental findings on the flow of sand down a steep chute. Nearly all granular flow models have a maximum value for the friction and therefore predict that flows on steep slopes will accelerate at a constant rate until the interaction with the ambient fluid becomes important. This prediction has not been tested by previous work, which has focused on relatively low slope angles where steady, fully developed flows occur after short distances. We test this by investigating flows over a much greater range of slope angles (30–50${}^{\ensuremath{\circ} } $) and flow depths (4–130 particle diameters). We examine flows with two basal conditions, one flat and frictional, the other bumpy. The latter imposes a no-slip condition for slow, deep flows, but permits some degree of slip for high flow velocities. The data suggests that friction can be much larger than theories such as the $\ensuremath{\mu} (I)$ rheology proposed by Jop, Forterre & Pouliquen (Nature, vol. 441, 2006) suggest and that there may be constant velocity states above the angle of vanishing ${h}_{\mathit{stop}} $. Although these flows do not vary in time, all but the flows on the bumpy base at low inclinations accelerate down the slope. A recirculation mechanism sustains flows with a maximum mass flux of $20~\mathrm{kg} ~{\mathrm{s} }^{\ensuremath{-} 1} $, allowing observations to be made at multiple points for each flow for an indefinite period. Flows with Froude number in the range 0.1–25 and bulk inertial number 0.1–2.7 were observed in the dense regime, with surface velocities in the range 0.2–5.6 $\mathrm{m} ~{\mathrm{s} }^{\ensuremath{-} 1} $. Previous studies have focused on $I\lessapprox 0. 5$. We show that a numerical implementation of the $\ensuremath{\mu} (I)$ rheology does not fully capture the accelerating dynamics or the transverse velocity profile on the bumpy base. We also observe the transverse separation of the flow into a dense core flanked by dilute regions and the formation of longitudinal vortices.
On the acoustic levitation stability behaviour of spherical and ellipsoidal particles
Authors: Foresti D. , Nabavi M. , Poulikakos D. 
Published: August 2012

AbstractWe present here an in-depth analysis of particle levitation stability and the role of the radial and axial forces exerted on fixed spherical and ellipsoidal particles levitated in an axisymmetric acoustic levitator, over a wide range of particle sizes and surrounding medium viscosities. We show that the stability behaviour of a levitated particle in an axisymmetric levitator is unequivocally connected to the radial forces: the loss of levitation stability is always due to the change of the radial force sign from positive to negative. It is found that the axial force exerted on a sphere of radius ${R}_{s} $ increases with increasing viscosity for ${R}_{s} / \lambda \lt 0. 0125$ ($\lambda $ is the acoustic wavelength), with the viscous contribution of this force scaling with the inverse of the sphere radius. The axial force decreases with increasing viscosity for spheres with ${R}_{s} / \lambda \gt 0. 0125$. The radial force, on the other hand, decreases monotonically with increasing viscosity. The radial and axial forces exerted on an ellipsoidal particle are larger than those exerted on a volume-equivalent sphere, up to the point where the ellipsoid starts to act as an obstacle to the formation of the standing wave in the levitator chamber.
The interaction between flow-induced vibration mechanisms of a square cylinder with varying angles of attack
Authors: Nemes András , Zhao Jisheng , Lo Jacono David , Sheridan John 
Published: August 2012

AbstractThis study examines the influence of angle of attack of a square section cylinder on the cylinder’s flow-induced vibration, where the direction of the vibration is transverse to the oncoming flow. Our experiments, which traversed the velocity–angle of attack parameter space in considerable breadth and depth, show that a low-mass ratio body can undergo combinations of both vortex-induced vibration and galloping. When the body has an angle of attack that makes it symmetric to the flow, such as when it assumes the square or diamond orientation, the two mechanisms remain independent. However, when symmetry is lost we find a mixed mode response with a new branch of vortex-induced oscillations that exceeds the amplitudes resulting from the two phenomena independently. The oscillations of this higher branch have amplitudes larger than the ‘upper branch’ of vortex-induced vibrations and at half the frequency. For velocities above this resonant region, the frequency splits into two diverging branches. Analysis of the amplitude response reveals that the transition between galloping and vortex-induced vibrations occurs over a narrow range of angle of incidence. Despite the rich set of states found in the parameter space the vortex shedding modes remain very similar to those found previously in vortex-induced vibration.