bluuebunny/crossref_metadata_2025 huggingface dataset:
Pinning of rotating waves to defects in finite Taylor–Couette flow
Authors: PACHECO J. R. , LOPEZ J. M. , MARQUES F.
Published: October 2010

Experiments in small aspect-ratio Taylor–Couette flows have reported the presence of a band in parameter space where rotating waves become steady non-axisymmetric solutions (a pinning effect) via infinite-period bifurcations. Previous numerical simulations were unable to reproduce these observations. Recent additional experiments suggest that the pinning effect is not intrinsic to the dynamics of the problem, but rather is an extrinsic response induced by the presence of imperfections. Here we present numerical simulations that include a small tilt of one of the endwalls, simulating the effects of imperfections that break the SO(2) axisymmetry of the problem, and indeed are able to reproduce the experimentally observed pinning of the rotating waves. Dynamical systems considerations suggest that any imperfection breaking the SO(2) axisymmetry of the problem must result in the formation of a pinning region of finite width. We have also found that the particulars of the pinning process, in particular the width of the pinning region, are extremely sensitive to the type of imperfection in the system. Almost identical flows respond in completely different ways to the same imperfection, depending on subtle differences in the weak secondary characteristics of the flow. The numerical simulations of the Navier–Stokes equations for the problem with an imposed tilt of an endwall together with normal-form analysis of a Hopf bifurcation subjected to imposed symmetry-breaking help shed some light on previous experiments that reported a variety of different dynamical behaviour for which a clear explanation was lacking.
Role of mitomycin C in reducing keloid recurrence: patient series and literature review
Authors: Gupta M , Narang T
Published: October 2010

Objective:

To study the role of mitomycin C in reducing keloid recurrence.

Study design:

Prospective, randomised, controlled trial.

Setting:

Tertiary care referral centre.

Patients:

Case series of 20 patients presenting with 26 pinna swellings, mostly following ear piercing.

Interventions:

We used the technique of surgical shave excision combined with topical application of mitomycin C and secondary wound healing, in all 26 pinnae.

Results:

Patients were followed up six to 24 months post-operatively. No recurrences were noted during this period.

Conclusion:

Keloids are fibrotic lesions resulting from abnormal wound healing. The uncontrolled proliferation of normal tissue healing processes results in scarring that enlarges well beyond the original wound margins. Successful treatment of keloids remains a challenge because this disease process has a high propensity for recurrence. Various therapies have previously been reported, and success rates are highly variable. We believe that shave excision followed by topical mitomycin C application is a promising treatment option for the management of pinna keloids.
Nasal tuberculosis – an update of current clinical and laboratory investigation
Authors: Masterson L , Srouji I , Kent R , Bath A P
Published: October 2010

Objective:

To report a case of primary nasal tuberculosis, and to discuss the diagnostic difficulties encountered.

Setting:

A teaching hospital in Norwich, UK.

Method:

Case report and review of the English language literature concerning tuberculosis affecting the head and neck region.

Result:

The diagnosis of nasal tuberculosis is based on: histological identification of granulomatous inflammation; positive testing for acid-alcohol resistant bacilli; and positive culture. Newer diagnostic tests have the advantage of speed and improved accuracy, but are not as yet completely evaluated for the diagnosis of extra-pulmonary tuberculosis.

Conclusion:

It is important to consider nasal tuberculosis in the initial differential diagnosis. The quest to exclude a malignancy may lead to unacceptable delays in treatment.
A Randomised Approximation Algorithm for Counting the Number of Forests in Dense Graphs
Authors: Annan J. D.
Published: October 2010

A polynomial-time randomised algorithm for uniformly generating forests in a dense graph is presented. Using this, a fully polynomial randomised approximation scheme (fpras) for counting the number of forests in a dense graph is created.
Lower Bounds for Insertion Methods for TSP
Authors: Azar Yossi
Published: October 2010

We show that the random insertion method for the traveling salesman problem (TSP) may produce a tour Ω(log log n/log log log n) times longer than the optimal tour. The lower bound holds even in the Euclidean Plane. This is in contrast to the fact that the random insertion method performs extremely well in practice. In passing, we show that other insertion methods may produce tours Ω(log n/log log n) times longer than the optimal one. No non-constant lower bounds were previously known.
Turán-Ramsey Theorems and Kp-Independence Numbers
Authors: Erdős P. , Hajnal A. , Simonovits M. , Sós V. T. , Szemerédi E.
Published: October 2010

Let the Kp-independence number αp (G) of a graph G be the maximum order of an induced subgraph in G that contains no Kp. (So K2-independence number is just the maximum size of an independent set.) For given integers r, p, m > 0 and graphs L1,…,Lr, we define the corresponding Turán-Ramsey function RTp(n, L1,…,Lr, m) to be the maximum number of edges in a graph Gn of order n such that αp(Gn) ≤ m and there is an edge-colouring of G with r colours such that the jth colour class contains no copy of Lj, for j = 1,…, r. In this continuation of [11] and [12], we will investigate the problem where, instead of α(Gn) = o(n), we assume (for some fixed p > 2) the stronger condition that αp(Gn) = o(n). The first part of the paper contains multicoloured Turán-Ramsey theorems for graphs Gn of order n with small Kp-independence number αp(Gn). Some structure theorems are given for the case αp(Gn) = o(n), showing that there are graphs with fairly simple structure that are within o(n2) of the extremal size; the structure is described in terms of the edge densities between certain sets of vertices.

The second part of the paper is devoted to the case r = 1, i.e., to the problem of determining the asymptotic value of

for p < q. Several results are proved, and some other problems and conjectures are stated.
A Stochastic Comparison for Arrangement Increasing Functions
Authors: Krieger Abba M. , Rosenbaum Paul R.
Published: October 2010

Let h(·) be an arrangement increasing function, let X have an arrangement increasing density, and let XE be a random permutation of the coordinates of X. We prove E{h(XE)} ≤ E{h(X)}. This comparison is delicate in that similar results are sometimes true and sometimes false. In a finite distributive lattice, a similar comparison follows from Holley's inequality, but the set of permutations with the arrangement order is not a lattice. On the other hand, the set of permutations is a lattice, though not a distributive lattice, if it is endowed with a different partial order, but in this case the comparison does not hold.
Non-Binary Matroids Having At Most Three Non-Binary Elements
Authors: Lemos Manoel
Published: October 2010

An element e of a matroid M is called non-binary when M\e and M/e are both non-binary matroids. Oxley in [5] gave a characterization of the 3-connected non-binary matroids without non-binary elements. In this paper, we will construct all the 3-connected matroids having 1, 2 or 3 non-binary elements.
Perfect Hashing and Probability
Authors: Nilli A.
Published: October 2010

A simple proof is given of the best-known upper bound on the cardinality of a set of vectors of length t over an alphabet of size b, with the property that, for every subset of k vectors, there is a coordinate in which they all differ. This question is motivated by the study of perfect hash functions.
Soft drinks consumption, diet quality and BMI in a Mediterranean population
Authors: Balcells Eva , Delgado-Noguera Mario , Pardo-Lozano Ricardo , Roig-González Taïs , Renom Anna , González-Zobl Griselda , Muñoz-Ortego Juan , Valiente-Hernández Susana , Pou-Chaubron Marina , Schröder Helmut
Published: October 2010

Objectives

Evidence of the effects of soft drinks consumption on BMI and lifestyle in adult populations is mixed and quite limited. The aim of the present study was to determine the association of soft drinks consumption with BMI and lifestyle in a representative Mediterranean population.

Design

Two independent, population-based, cross-sectional (2000 and 2005) studies. Dietary intake was assessed using a validated FFQ. Weight and height were measured.

Setting

Girona, Spain.

Subjects

Random sample of the 35- to 74-year-old population (3910 men and 4285 women).

Results

Less than half (41·7 %) of the population consumed soft drinks; the mean consumption was 36·2 ml/d. The prevalence of sedentary lifestyle increased with the frequency of soft drinks consumption (P= 0·025). Daily soft drinks consumption significantly increased the risk of low adherence to the Mediterranean diet (OR = 0·57, 95 % CI 0·44, 0·74v. top tertile of Mediterranean diet score). Multiple linear regression analyses, controlled for potential confounders, revealed that an increment in soft drinks consumption of 100 ml was associated with a 0·21 kg/m2increase in BMI (P= 0·001). Only implausibly low reports of energy consumption showed a null association between soft drinks consumption and BMI.

Conclusions

Soft drinks consumption was not embedded in a healthy diet context and was positively associated with BMI and sedentary lifestyle in this Mediterranean population.
Recruitment of volunteers for a home-delivered meals programme serving homebound older adults: a theoretically derived programme among faith communities
Authors: Buys David R , Marler Malcolm L , Robinson Caroline O , Hamlin Christopher M , Locher Julie L
Published: October 2010

Objective

Home-delivered nutrition programmes that are federally subsidized by the US Administration on Aging seek to ensure that socially isolated older adults who are unable to purchase and prepare their own food have nutritious meals delivered to them regularly by both employed and volunteer staff. Unfortunately, there are long waiting lists in some neighbourhoods that are often due to a shortage of volunteers. The present paper describes a theoretically driven community-based project designed to increase volunteer participation in serving Meals on Wheels (MOW) clients.

Design

A Support Team model was applied in the project wherein existing social capital among religious faith communities, and social networks within those organizations, was joined with a local MOW programme to create a sustainable meal delivery route to vulnerable homebound older adults.

Setting

The programme participants were in one underserved neighbourhood in Birmingham, Alabama, an urban city in the south-eastern USA.

Subjects

The subjects under consideration are both MOW clients and volunteers. MOW clients are those individuals aged 60 years and above who qualify for the service; the volunteers are from community churches.

Results

One volunteer route, comprising six congregations that delivered meals to sixteen homebound older adults, was created. The route served more than 2000 meals in 2006 (the year the programme began) and continues to serve clients today.

Conclusions

The programme’s successful implementation provides evidence that reliance on theory is critical in planning and developing effective community-based programme interventions.
Les Juges Constituants
Authors: JHR  , WTE
Published: October 2010

Constituent power of the courts, in dialogue, accommodation or even collaboration, has become undeniable. It raises at least two points for scholarship to contemplate. First, what is the foundation of this power in terms of classical constitutional theory? Second, instead of or apart from the courts and their interactions: what is the relationship, in this constituent activity, between the courts and the political institutions, including the people?
Wir Sind das Volk: Notes About the Notion of ‘The People’ as Occasioned by the Lissabon-Urteil
Authors: Eijsbouts W.T.
Published: October 2010

Leipzig 1989: dissolution of the East German state people or Staatsvolk – Karlsruhe 2020: dissolution of the German people – Courts and the people as a neglected constitutional relationship – Bundesverfassungsgericht's versions of the people – Analysis of the concept of people – Forms of action – Political people breaks down into two: original and electoral people – Marbury v. Madison – Duality as a matter of doctrine and principle – Duality in Lissabon Urteil – Conflation and reduction of authority to vote – Subordination of electoral to original people – The Court's logic pushed into motion – Exposing the constitution
Locke and the State of Exception: Towards a Modern Understanding of Emergency Government
Authors: de Wilde Marc
Published: October 2010

Post 9/11 debate – John Locke important reference – Modern notion, transformation of sovereignty – From legal to political nature of the exception – From temporary to permanent – From preservation of realm to defense of life – Change of the experience of time – Locke ambivalent, transition to modern understanding – Necessity, trust and resistance – Logic of exceptionality – Locke's remaining relevancew
The Strasbourg Court on the Dayton Constitution: Judgment in the case of Sejdić and Finci v. Bosnia and Herzegovina, 22 December 2009
Authors: Bardutzky Samo
Published: October 2010

On 22 December 2009, the Grand Chamber of the European Court of Human Rights (hereafter: the Court) issued a judgment on the applications filed by two citizens of Bosnia and Herzegovina, Mr Dervo Sejdić and Mr Jakob Finci. It found a violation of their rights under the Convention for the Protection of Human Rights and Fundamental Freedoms and under the Protocols to the Convention. Bosnia and Herzegovina had violated the applicants' rights under Article 14 of the Convention in conjunction with Article 3 of Protocol to the Convention for the Protection of Human Rights and Fundamental Freedoms and under Article 1 of Protocol No. 12 to the Convention for the Protection of Human Rights and Fundamental Freedoms.
Elias Howe, William Bradbury Ryan, and Irish Music in Nineteenth-Century Boston
Authors: WELLS PAUL F.
Published: October 2010

Ryan's Mammoth Collectionis a compendium of fiddle tunes assembled by William Bradbury Ryan. Originally published in Boston in 1883 by Elias Howe, Jr., it has remained in print in one form or another ever since. It has been used as a source of tunes by many generations of fiddlers in different stylistic traditions, but its value as a descriptive document of the repertoire of late-nineteenth-century Boston, particularly the Irish community in that city, has largely been overlooked. Ryan, rather than Capt. Francis O'Neill of Chicago, should be regarded as the first great documentarian of Irish traditional music in the United States.
No Yankee Doodling: Notable Trends and Traditional Recordings from Irish America
Authors: HITCHNER EARLE
Published: October 2010

The emergence of the compact disc in 1979 was regarded as the likely sales salvation of recorded music, and for many years the CD reigned supreme, generating steady, often substantial, company profits. More recently, however, the music industry has painfully slipped a disc. The CD has been in sharp decline, propelled mainly by young consumer ire over price and format inflexibility and by Internet technology available to skirt or subvert both. Irish American traditional music has not been impervious to this downward trend in sales and to other challenging trends and paradigm shifts in recording and performing. Amid the tumult, Irish American traditional music has nevertheless shown a new resilience and fresh vitality through a greater do-it-yourself, do-more-with-less spirit of recording, even for established small labels. The five recent albums of Irish American traditional music reviewed here—three of which were released by the artists themselves—exemplify a trend of their own, preserving the best of the past without slavishly replicating it. If the new mantra of music making is adapt or disappear, then Irish American traditional music, in adapting to change free of any impulse to dumb down, is assured of robustly enduring.
Frictional strength and strain weakening in simulated fault gouge: Competition between geometrical weakening and chemical strengthening
Authors: Niemeijer André , Marone Chris , Elsworth Derek
Published: October 2010

Despite the importance of hydromechanical effects in fault processes, not much is known about the interplay of chemical and mechanical processes, in part because the conditions are difficult to simulate in the laboratory. We report results from an experimental study of simulated fault gouge composed of rock salt sheared under conditions where pressure solution is known to operate. At sliding velocities above 10 μm/s and high shear strains (>5), friction measurements show that layers of rock salt weaken significantly and ultimately slide unstably (i.e., stick‐slip). Microstructural observations show the presence of a zone of comminuted grains along shear zone boundaries, forming boundary‐parallel Y shears at high sliding velocities. Samples deformed at low sliding velocities do not show boundary‐parallel shear but rather exhibit low porosity passive regions isolated by dilational zones in the Riedel shear orientation. We posit that the significant strain weakening observed at high sliding velocities is caused by severe grain size reduction as shear localization develops, i.e., by frictional wear, ultimately leading to the development of a throughgoing boundary parallel Y shear. Unstable slip is probably related to rupture on this Y shear surface with intermittent healing of the asperities by pressure solution. Furthermore, the data show that the weakening and subsequent unstable slip can be delayed (i.e., occur at higher strains) by lower sliding velocities, larger initial grain sizes, lower normal stresses, and the presence of fluids. This suggests a competition between mechanical wear and chemical processes. Our data highlight the importance of hydrothermal processes in tectonic faulting.
Characterization of cloud liquid water content distributions from CloudSat
Authors: Lee Seungwon , Kahn Brian H. , Teixeira João
Published: October 2010

The development of realistic cloud parameterizations requires accurate characterizations of subgrid distributions of thermodynamic variables. To this end, cloud liquid water content (CLWC) distributions are characterized with respect to cloud phase, cloud type, precipitation occurrence, and geolocation using CloudSat radar measurements. The probability density function (PDF) of CLWC is estimated using maximum likelihood estimation. The best‐estimated PDF of CLWC is found to follow either a gamma or a lognormal distribution depending on temperature (cloud phase), cloud type, the occurrence of precipitation, and geolocation. The data sampling with respect to cloud phase and precipitation significantly affects the distributional characteristics of CLWC in some regions. In the lower to midtroposphere (altitudes of 1–6 km) in the tropics and subtropics, where nonprecipitating and pure liquid phase clouds are dominant, the PDFs of CLWC are best described by lognormal distributions. In contrast, at altitudes above 6 km and in regions poleward of the midlatitudes, the CLWC more closely resembles a gamma distribution that coincides with a high frequency of occurrence of supercooled liquid clouds containing low CLWC values. When the contributions of supercooled water and precipitation are removed, the CLWC PDFs transition from gamma to lognormal distributions in two areas: (1) the high altitude and middle‐to‐polar latitude regions where the contribution of supercooled cloud is significant and (2) in the lower troposphere where precipitation is frequently detected. Although the CloudSat radar does not sample all cloud hydrometeors, coherent regional and cloud type dependence of CLWC distributional characteristics are observed that may provide useful constraints for cloud parameterizations in climate models.
Meander dynamics: A nonlinear model without curvature restrictions for flow in open‐channel bends
Authors: Blanckaert K. , de Vriend H. J.
Published: October 2010

Despite the rapid evolution of computational power, simulation of meander dynamics by means of reduced and computationally less expensive models remains practically relevant for investigation of large‐scale and long‐term processes, probabilistic predictions, or rapid assessments. Existing meander models are invariantly based on the assumptions of mild curvature and slow curvature variations and fail to explain processes in the high‐curvature range. This article proposes a nonlinear model for meander hydrodynamics without curvature restrictions. It provides the distribution of the main flow, the magnitude of the secondary flow, the direction of the bed shear stress, and the curvature‐induced additional energy losses. It encompasses existing mild curvature models, remains valid for straight flow, and agrees satisfactorily with experimental data from laboratory experiments under conditions that are more demanding than sharp natural river bends. The proposed model reveals the mechanisms that drive the velocity redistribution in meander bends and their dependence on the river's roughness Cf, the flow depth H, the radius of curvature R, the width B, and bathymetric variations. It identifies Cf−1H/R as the major control parameter for meander hydrodynamics in general and the relative curvature R/B for sharp curvature effects. Both parameters are small in mildly curved bends but O(1) in sharply curved bends, resulting in significant differences in the flow dynamics. Streamwise curvature variations are negligible in mildly curved bends, but they are the major mechanisms for velocity redistribution in sharp bends. Nonlinear feedback between the main and secondary flow also plays a dominant role in sharp bends: it increases energy losses and reduces the secondary flow, the transverse bed slope, and the velocity redistribution.
Corruption of accuracy and efficiency of Markov chain Monte Carlo simulation by inaccurate numerical implementation of conceptual hydrologic models
Authors: Schoups G. , Vrugt J. A. , Fenicia F. , van de Giesen N. C.
Published: October 2010

Conceptual rainfall‐runoff models have traditionally been applied without paying much attention to numerical errors induced by temporal integration of water balance dynamics. Reliance on first‐order, explicit, fixed‐step integration methods leads to computationally cheap simulation models that are easy to implement. Computational speed is especially desirable for estimating parameter and predictive uncertainty using Markov chain Monte Carlo (MCMC) methods. Confirming earlier work of Kavetski et al. (2003), we show here that the computational speed of first‐order, explicit, fixed‐step integration methods comes at a cost: for a case study with a spatially lumped conceptual rainfall‐runoff model, it introduces artificial bimodality in the marginal posterior parameter distributions, which is not present in numerically accurate implementations of the same model. The resulting effects on MCMC simulation include (1) inconsistent estimates of posterior parameter and predictive distributions, (2) poor performance and slow convergence of the MCMC algorithm, and (3) unreliable convergence diagnosis using the Gelman‐Rubin statistic. We studied several alternative numerical implementations to remedy these problems, including various adaptive‐step finite difference schemes and an operator splitting method. Our results show that adaptive‐step, second‐order methods, based on either explicit finite differencing or operator splitting with analytical integration, provide the best alternative for accurate and efficient MCMC simulation. Fixed‐step or adaptive‐step implicit methods may also be used for increased accuracy, but they cannot match the efficiency of adaptive‐step explicit finite differencing or operator splitting. Of the latter two, explicit finite differencing is more generally applicable and is preferred if the individual hydrologic flux laws cannot be integrated analytically, as the splitting method then loses its advantage.
A formal likelihood function for parameter and predictive inference of hydrologic models with correlated, heteroscedastic, and non‐Gaussian errors
Authors: Schoups Gerrit , Vrugt Jasper A.
Published: October 2010

Estimation of parameter and predictive uncertainty of hydrologic models has traditionally relied on several simplifying assumptions. Residual errors are often assumed to be independent and to be adequately described by a Gaussian probability distribution with a mean of zero and a constant variance. Here we investigate to what extent estimates of parameter and predictive uncertainty are affected when these assumptions are relaxed. A formal generalized likelihood function is presented, which extends the applicability of previously used likelihood functions to situations where residual errors are correlated, heteroscedastic, and non‐Gaussian with varying degrees of kurtosis and skewness. The approach focuses on a correct statistical description of the data and the total model residuals, without separating out various error sources. Application to Bayesian uncertainty analysis of a conceptual rainfall‐runoff model simultaneously identifies the hydrologic model parameters and the appropriate statistical distribution of the residual errors. When applied to daily rainfall‐runoff data from a humid basin we find that (1) residual errors are much better described by a heteroscedastic, first‐order, auto‐correlated error model with a Laplacian distribution function characterized by heavier tails than a Gaussian distribution; and (2) compared to a standard least‐squares approach, proper representation of the statistical distribution of residual errors yields tighter predictive uncertainty bands and different parameter uncertainty estimates that are less sensitive to the particular time period used for inference. Application to daily rainfall‐runoff data from a semiarid basin with more significant residual errors and systematic underprediction of peak flows shows that (1) multiplicative bias factors can be used to compensate for some of the largest errors and (2) a skewed error distribution yields improved estimates of predictive uncertainty in this semiarid basin with near‐zero flows. We conclude that the presented methodology provides improved estimates of parameter and total prediction uncertainty and should be useful for handling complex residual errors in other hydrologic regression models as well.
Vertical structure of raindrop size distribution in lower atmospheric boundary layer
Authors: Yoshikawa Eiichi , Kida Satoshi , Yoshida Satoru , Morimoto Takeshi , Ushio Tomoo , Kawasaki Zen
Published: October 2010

We examine the vertical structure of the raindrop size distribution (DSD) in the lower atmospheric boundary layer (ABL) below altitudes of 300 m, where conventional radars typically do not observe. The DSD in the lower ABL is retrieved using Ku‐band broadband radar (BBR) having an observational range of 50 m to 15 km, and a high range resolution of several meters and a 3‐dB beam width of 3 deg. The radar‐retrieved DSD are in excellent agreement with the DSD measured with a co‐located, 2 dimensional video disdrometer with correlation coefficients over 0.96 in both stratiform and convective rain events. While the DSD reveals no significant change in the stratiform event, the growth process increases about 2 times in the number of raindrops larger than 0.5 mm in diameter in the convective event. This growth process in the ABL is important when we discuss the rainfall rate from radar reflectivity factor.
Climate response to tropical cyclone‐induced ocean mixing in an Earth system model of intermediate complexity
Authors: Sriver Ryan L. , Goes Marlos , Mann Michael E. , Keller Klaus
Published: October 2010

We introduce a parameterization of ocean mixing by tropical cyclones (TCs) into an Earth system model of intermediate complexity. The parameterization is based on previously published global budgets of TC‐induced mixing derived from high‐resolution satellite measurements of anomalous sea surface temperatures along storm tracks. Recognizing the caveats introduced, for example, by the simplified model structure, we find that the representation of realistic TC‐induced mixing substantially alters the equilibrium conditions of (1) the thermal structure of the upper ocean, (2) the surface energy budget, and (3) the circulation in the equatorial to subtropical Pacific Ocean. These changes result in warmer upwelling regions in the eastern equatorial Pacific and an overall increase in ocean heat content consistent with the recent TC heat pump hypothesis. Spatial variability in the mixing appears to be a key factor in the modeled response. We find no substantial influence of the considered TC‐induced mixing on poleward ocean heat transport in the analyzed model. Our results suggest that climate‐sensitive mixing feedbacks are plausible; however, the large‐scale effect is mainly confined to the subtropical Indo‐Pacific region for present‐day TC climatology.
Compact intracloud lightning discharges: 1. Mechanism of electromagnetic radiation and modeling
Authors: Nag Amitabh , Rakov Vladimir A.
Published: October 2010

On the basis of experimental evidence of multiple reflections and modeling, we infer that, from the electromagnetic point of view, the so‐called compact intracloud lightning discharge (CID) is essentially a bouncing‐wave phenomenon. The shortest radiating‐channel length appears to be about 100 m. Reflections, occurring at CID channel ends, influence the magnitude of the overall CID electric field waveform and are responsible for its fine structure, as well as, by inference, for “noisiness” of dE/dt waveforms and for accompanying HF‐VHF bursts. From modeling the CID as a wave traveling on an elevated vertical transmission line and comparing model‐predicted electric fields with measurements, we estimated that the effective current reflection coefficients at channel ends (additionally accounting for current attenuation along the channel) should be in the range of 0 to −0.5, that the wave propagation speed ranges from 0.3 to 3 × 108 m/s, and the channel length is less than 1000 m. In these calculations, we assumed that the current wave had a zero‐to‐peak risetime of 6 μs and a total duration of 30 μs. Influence of current risetime on field waveforms was also examined, and it was found to be typically in the range from about 2 to 8.5 μs.
Compact intracloud lightning discharges: 2. Estimation of electrical parameters
Authors: Nag Amitabh , Rakov Vladimir A.
Published: October 2010

We estimated electrical parameters of 48 located compact intracloud discharges (CIDs) using their measured electric fields and vertical Hertzian dipole approximation. This approximation is consistent with the more general bouncing‐wave CID model for a reasonably large subset of allowed combinations of propagation speed and channel length. For nine events, we estimated channel lengths from observed reflection signatures in measured dE/dt waveforms and assumed propagation speeds between 2 × 108 m/s and 3 × 108 m/s, which limit the range of allowed values. For a speed of 2.5 × 108 m/s (average value), the channel lengths for these nine events ranged from 108 to 142 m. The corresponding geometric mean values (GM) of peak current, zero‐to‐peak current risetime, and charge transfer in the first 5 μs are 143 kA, 5.4 μs, and 303 mC, respectively. The GM peak radiated power and energy radiated in the first 5 μs are 29 GW and 24 kJ, respectively. For the remaining 39 events, there were no reflection signatures observed, and the channel length was assumed to be 350 m, for which the Hertzian dipole approximation is valid for speeds in the range of 2 to 3 × 108 m/s. In this case, GM values of peak current, zero‐to‐peak current risetime, and charge transfer in the first 5 μs are 64 kA, 4.9 μs, and 142 mC, respectively. The GM peak radiated power and energy radiated in the first 5 μs are 28 GW and 32 kJ, respectively.
Host genetic background affects regulatory T‐cell activity that influences the magnitude of cellular immune response against Mycobacterium tuberculosis
Authors: Paula Marina Oliveira , Fonseca Denise Morais , Wowk Pryscilla Fanini , Gembre Ana Flávia , Fedatto Paola Fernanda , Sérgio Cássia Alves , Silva Célio Lopes , Bonato Vânia Luiza Deperon
Published: October 2010

Using two mouse strains with different abilities to generate interferon (IFN)‐γ production after Mycobacterium tuberculosis infection, we tested the hypothesis that the frequency and activity of regulatory T (Treg) cells are influenced by genetic background. Our results demonstrated that the suppressive activity of spleen Treg cells from infected or uninfected BALB/c mice was enhanced, inhibiting IFN‐γ and interleukin (IL)‐2 production. Infected C57BL/6 mice exhibited a decrease in the frequency of lung Treg cells and an increased ratio CD4+:CD4+Foxp3+ cells compared with infected BALB/c mice and uninfected C57BL/6 mice. Moreover, infected C57BL/6 mice also had a decrease in the immunosuppressive capacity of spleen Treg cells, higher lung IFN‐γ and IL‐17 production, and restricted the infection better than BALB/c mice. Adoptive transfer of BALB/c Treg cells into BALB/c mice induced an increase in bacterial colony‐forming unit (CFU) counts. Furthermore, BALB/c mice treated with anti‐CD25 antibody exhibited lung CFU counts significantly lower than mice treated with irrelevant antibody. Our results show that in BALB/c mice, the Treg cells have a stronger influence than that in C57BL/6 mice. These data suggest that BALB/c and C57BL/6 mice may use some different mechanisms to control M. tuberculosis infection. Therefore, the role of Treg cells should be explored during the development of immune modulators, both from the perspective of the pathogen and the host.
Human immunodeficiency virus‐1 vaccine design: where do we go now?
Authors: Wijesundara Danushka K , Jackson Ronald J , Ramshaw Ian A , Ranasinghe Charani
Published: October 2010

Numerous human immunodeficiency virus (HIV)‐1 vaccines have been developed over the last three decades, but to date an effective HIV‐1 vaccine that can be used for prophylactic or therapeutic purposes in humans has not been identified. The failures and limited successes of HIV‐1 vaccines have highlighted the gaps in our knowledge with regard to fundamental immunity against HIV‐1 and have provided insights for vaccine strategies that may be implemented for designing more effective HIV‐1 vaccines in the future. Recent studies have shown that robust mucosal immunity, high avidity and polyfunctional T cells, and broadly neutralizing antibodies are important factors governing the induction of protective immunity against HIV‐1. Furthermore, optimization of vaccine delivery methods for DNA or live viral vector‐based vaccines, elucidating the immune responses of individuals who remain resistant to HIV‐1 infections and also understanding the core immune responses mediating protection against simian immunodeficiency viruses (SIV) and HIV‐1 in animal models following vaccination, are key aspects to be regarded for designing more effective HIV‐1 vaccines in the future.
Insight into human alveolar macrophage and M. tuberculosis interactions via metabolic reconstructions
Authors: Bordbar Aarash , Lewis Nathan E , Schellenberger Jan , Palsson Bernhard Ø , Jamshidi Neema
Published: October 2010

Metabolic coupling of Mycobacterium tuberculosis to its host is foundational to its pathogenesis. Computational genome‐scale metabolic models have shown utility in integrating ‐omic as well as physiologic data for systemic, mechanistic analysis of metabolism. To date, integrative analysis of host–pathogen interactions using in silico mass‐balanced, genome‐scale models has not been performed. We, therefore, constructed a cell‐specific alveolar macrophage model, iAB‐AMØ‐1410, from the global human metabolic reconstruction, Recon 1. The model successfully predicted experimentally verified ATP and nitric oxide production rates in macrophages. This model was then integrated with an M. tuberculosis H37Rv model, iNJ661, to build an integrated host–pathogen genome‐scale reconstruction, iAB‐AMØ‐1410‐Mt‐661. The integrated host–pathogen network enables simulation of the metabolic changes during infection. The resulting reaction activity and gene essentiality targets of the integrated model represent an altered infectious state. High‐throughput data from infected macrophages were mapped onto the host–pathogen network and were able to describe three distinct pathological states. Integrated host–pathogen reconstructions thus form a foundation upon which understanding the biology and pathophysiology of infections can be developed.
Alkyl Derivatives of Bismuth in Environmental and Biological Media
Authors: Filella Montserrat
Published: October 2010

Knowledge about methylated species of bismuth in environmental and biological media is very limited. The presence of volatile trimethylbismuthine has been unequivocally detected in landfill and sewage fermentation gases but the trace concentrations of methylated bismuth species reported in a few polluted soils and sediments probably require further confirmation. In contrast to arsenic and antimony, no methylated bismuth species have ever been found in surface waters and biota. Volatile monomethyl-, dimethyl- and trimethylbismuthine have been produced by some anaerobic bacteria and methanogenic archaea in laboratory culture experiments. Bismuth methylation differs significantly from the one of arsenic and antimony because no Bi(V) compound is known to be formed in biological and environmental media. Moreover, alkylbismuth compounds are rather instable due to the easy cleavage of the weak Bi-C bond.
Direct Carbon Fuel Cells
Authors: Desclaux P. , Nürnberger S. , Stimming U.
Published: October 2010

Direct carbon fuel cells (DCFCs) are high temperature fuel cells which offer the possibility to directly convert the chemical energy of carbon materials (e.g. coal, lignite, char, carbonized biomass) into electricity. In addition to using solid carbon fuels, higher overall efficiencies should be possible because the thermodynamic efficiency is close to 100 %. This means higher than those of conventional fuel cell types for gaseous fuels.

DCFC technology can employ three different electrolyte types: Molten carbonate electrolyte (liquid salt), molten hydroxide electrolyte (liquid salt) and solid oxide electrolyte (solid ceramic layer). Recently, also combined technologies have been developed.

In this chapter, all the concepts are described and their advantages and difficulties are discussed.
Electrolysis Using Fuel Cell Technology
Authors: Brisse A. , Schefold J. , Stoots C. , O’Brien J.
Published: October 2010

Present global hydrogen demand is met to a large extent by fossil fuels. Hydrogen is produced via alkaline electrolysis of water only, when the required electric energy is readily available. Alternatively, hydrogen can be produced by water electrolysis with reversibly operated fuel cells, PEMFCs or SOFCs. PEM electrolysis is technologically mature with an energy-conversion efficiency (electrical-to-chemical) somewhat above the one of alkaline electrolysis (70-80%).

Higher efficiency for electrolysis is expected with increasing temperature as consequence of the decrease of the molar Gibbs energy of the reaction. This was first confirmed with the reversible operation of tubular SOFCs as solid oxide electrolyser cells (SOECs) in pioneering works in the 1980ies. With present SOFCs operated as SOECs, notably the planar cells, the theoretically predicted efficiencies are more and more approached in the experiment. State-of-the-art SOECs may be operated with and without external heat supply; already without heat supply the electrical-to-chemical energy-conversion efficiency is above the one of low temperature electrolysers. Operation cell voltages are around 1.1 to 1.3 V at 800°C at a Faradaic efficiency of 100%. The high efficiency may render the SOEC technology attractive for the storage of (intermittent) renewable energy, such as wind or solar.

In this chapter, examples for the actual state of research on SOECs as well as on SOEC stacks and systems are given, notably their current-voltage response and behaviour under long-term operation. Moreover, some development options – and potential hurdles like cell degradation – are summarised for this potentially new branch of the solid oxide cell technology.
Transportation Biofuels
Authors: Hoogendoorn Alwin , van Kasteren Han JMNV
Published: October 2010

Current world fossil oil production is struggling to meet demand and may even show a decline after 2010. It is therefore necessary to develop new energy efficient production pathways for transportation biofuels. This book offers an insight into three promising and innovative pathways for the biological production of biodiesel, ethanol and methane. These unconventional methods should provide higher product yields, less stringent feedstock specifications, lower chemical additive demand, reduced waste production and much better energy balances when compared to more traditional methods. The first pathway is the enzymatic production of a new kind of biodiesel where no glycerol waste is produced and a twenty percent higher product yield is obtained. The other two pathways are based on the biological conversion of syngas into ethanol or methane using various kinds of lignocellulosic biomass as the starting point. For each of the three pathways a comparison will be made with competing production methods. The contents reflect extended desktop research and show practical experimental results. Government scientists, academics and biofuel producers with an interest in novel transportation fuels will all find this book to be essential reading.
Stereoselective synthesis of 1,2-cis-glycosylic linkages
Authors: Carmona Ana T. , Moreno-Vargas Antonio J. , Robina Inmaculada
Published: October 2010

Stereoselective methods for the preparation of 1,2-cis-O-glycosides and 1,2-cis-C-glycosyl compounds are presented.
Bilingualism and Aging
Authors: Ardila Alfredo , Ramos Eliane
Published: October 2010

Language mediates not only the social relationship systems, but also the control of cognitive processes. Potential differences between bilinguals and monolinguals in age-associated cognitive decline during normal and abnormal aging have been suggested. A research review of the area suggests that normal aging is associated with increased interference between the two languages. Regression to the primary language can be considered as a predictor of dementia. Recent research has reported that bilingualism can have a protective effect during aging. Bilinguals are usually faster in performing different attention tasks, and more efficient in tests of executive control. Research has supported the assumption that using two or more different languages frequently can provide not only some social, but also cognitive, advantages during normal and abnormal aging.
Suppression of current fluctuations in an intense electron beam
Authors: Harris J. R. , Lewellen J. W.
Published: October 2010

When an intense beam encounters an aperture, the transmitted current depends on the properties of the beam and the transport channel, as well as those of the aperture itself. In some cases, an increase in the incident beam current will be exactly compensated by an increase in the incident beam area, so that the current density at the aperture remains unchanged. When this occurs, the transmitted beam current becomes independent of changes in the incident beam current, providing a passive means for suppressing current fluctuations in the beam. In this article, a key requirement for the existence of this condition is derived. This requirement is shown to be fulfilled in the case of an idealized uniform focusing channel in the small-signal limit, but to be violated when the current fluctuations are not small. Even in this case, the apertured transport system retains the ability to suppress—but not totally eliminate—fluctuations in the transmitted beam current for a wide range of incident beam currents.
On the interpretation of Langmuir probe data inside a spacecraft sheath
Authors: Olson J. , Brenning N. , Wahlund J.-E. , Gunell H.
Published: October 2010

If a Langmuir probe is located inside the sheath of a negatively charged spacecraft, there is a risk that the probe characteristic is modified compared to that of a free probe in the ambient plasma. We have studied this probe-in-spacecraft-sheath problem in the parameter range of a small Langmuir probe (with radius rLP⪡λD) using a modified version of the orbit motion limited (OML) probe theory. We find that the ambient electron contribution Ie(ULP) to the probe characteristic is suitably analyzed in terms of three regions of applied probe potential ULP. In region I, where the probe is negatively charged (i.e., ULP<U1, where U1 is the potential in the sheath at the probe position), the probe characteristic Ie(ULP) is close to that of OML theory for a free probe in the ambient plasma. In the probe potential range ULP>U1, there is first a transition region II in applied potential, U1<ULP<U2, in which the key factor to determine the shape of Ie(ULP) is a potential minimum UM between the probe and the ambient plasma. This minimum gives the depth Upl−UM of a potential barrier that prevents the lowest energy ambient electrons from reaching the probe. For a high enough positive probe potential, in region III, the barrier becomes small. Here, Ie(ULP) again approaches OML theory for a free probe. The boundary U2 between regions II and III is somewhat arbitrary; we propose a condition on the barrier, Upl−UM⪡kBTe/e, as the definition of region III. The main findings in this work are qualitative rather than quantitative. The existence of the transition region points to that special care must be taken to extract plasma parameters from measured I(ULP) as the probe characteristic is likely to depart from usual OML in crucial respects: (1) the ambient plasma potential Upl falls into the transition region, but there is no obvious knee or other feature to identify it, (2) there is in this region no exponential part of Ie(ULP) that can be used to obtain Te, instead, (3) the probe size is important in determining the curve shape. We have tentatively applied our simplified probe-in-sheath model to real probe data from the Cassini spacecraft, taken in the dense plasma of Saturn’s magnetosphere. We propose that our model gives a better description than OML of measured Langmuir probe sweeps in space plasmas where the Langmuir probe is situated within the spacecraft sheath, i.e., for long Debye lengths. The understanding of these probe sweep effects in such regions may improve by self-consistent particle simulations of the spacecraft environment.
An imaging proton spectrometer for short-pulse laser plasma experiments
Authors: Chen Hui , Hazi A. U. , van Maren R. , Chen S. N. , Fuchs J. , Gauthier M. , Le Pape S. , Rygg J. R. , Shepherd R.
Published: October 2010

The ultraintense short pulse laser pulses incident on solid targets can generate energetic protons. In addition to their potentially important applications such as in cancer treatments and proton fast ignition, these protons are essential to understand the complex physics of intense laser plasma interaction. To better characterize these laser-produced protons, we designed and constructed a novel spectrometer that will not only measure proton energy distribution with high resolution but also provide its angular characteristics. The information obtained from this spectrometer compliments those from commonly used diagnostics including radiochromic film packs, CR39 nuclear track detectors, and nonimaging magnetic spectrometers. The basic characterizations and sample data from this instrument are presented.