bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ROMAN CARCER AND ITS ADJUNCTS
Authors: CADOUX T. J.
Published: August 2010

This paper attempts to set out what is known about the places in the city of Rome used for detention and execution. It is not based on personal inspection of the sites, but only on the ancient evidence and modern discussion, and simply aims to meet the absence of a full up-to-date account in English of the history, location, character and function of these places, viz. the carcer, lautumiae, Saxum Tarpeium, Scalae Gemoniae, and the elusive robur. It does not deal with the wider question of what crimes merited the death penalty or called for its infliction in this or that manner, nor, apart from a few items, is it carried beyond the Julio-Claudian dynasty.
Plant breeding and climate changes
Authors: CECCARELLI S. , GRANDO S. , MAATOUGUI M. , MICHAEL M. , SLASH M. , HAGHPARAST R. , RAHMANIAN M. , TAHERI A. , AL-YASSIN A. , BENBELKACEM A. , LABDI M. , MIMOUN H. , NACHIT M.
Published: August 2010

Climate change is now unequivocal, particularly in terms of increasing temperature, increasing CO2concentration, widespread melting of snow and ice and rising global average sea level, while the increase in the frequency of drought is very probable but not as certain.

However, climate changes are not new and some of them have had dramatic impacts, such as the appearance of leaves about 400 million years ago as a response to a drastic decrease in CO2concentration, the birth of agriculture due to the end of the last ice age about 11 000 years ago and the collapse of civilizations due to the late Holocene droughts between 5000 and 1000 years ago.

The climate changes that are occurring at present will have – and are already having – an adverse effect on food production and food quality with the poorest farmers and the poorest countries most at risk. The adverse effect is a consequence of the expected or probable increased frequency of some abiotic stresses such as heat and drought, and of the increased frequency of biotic stresses (pests and diseases). In addition, climate change is also expected to cause losses of biodiversity, mainly in more marginal environments.

Plant breeding has addressed both abiotic and biotic stresses. Strategies of adaptation to climate changes may include a more accurate matching of phenology to moisture availability using photoperiod-temperature response, increased access to a suite of varieties with different duration to escape or avoid predictable occurrences of stress at critical periods in crop life cycles, improved water use efficiency and a re-emphasis on population breeding in the form of evolutionary participatory plant breeding to provide a buffer against increasing unpredictability. ICARDA, in collaboration with scientists in Iran, Algeria, Jordan, Eritrea and Morocco, has recently started evolutionary participatory programmes for barley and durum wheat. These measures will go hand in hand with breeding for resistance to biotic stresses and with an efficient system of variety delivery to farmers.
A STATE-LEVEL ANALYSIS OF LIFE EXPECTANCY IN MEXICO (1990–2006)
Authors: PELÁEZ OSCAR , GUIJARRO MARTA , ARIAS MERCEDES
Published: August 2010

Using a methodology similar to that proposed by Barro & Sala-i-Martin (1995), it is found that, in the period 1990–2006, there was strong convergence among state-level life expectancy series, but a distancing in life expectancy in the Mexican Republic compared with more developed countries, especially during the new millennium. The interior convergence had taken place at the expense of the exterior; that is, not so much as a result of an improvement in living conditions in the poorer states, but more due to the low performance of the richer states. The causes of this situation are explained using the concept of ‘epidemiological transition’.
Experimental evidence of stable wave patterns on deep water
Authors: HENDERSON DIANE M. , SEGUR HARVEY , CARTER JOHN D.
Published: August 2010

Recent predictions from competing theoretical models have disagreed about the stability/instability of bi-periodic patterns of surface waves on deep water. We present laboratory experiments to address this controversy. Growth rates of modulational perturbations are compared to predictions from: (i) inviscid coupled nonlinear Schrödinger (NLS) equations, according to which the patterns are unstable and (ii) dissipative coupled NLS equations, according to which they are linearly stable. For bi-periodic wave patterns of small amplitude and nearly permanent form, we find that the dissipative model predicts the experimental observations more accurately. Hence, our experiments support the claim that these bi-periodic wave patterns are linearly stable in the presence of damping. For bi-periodic wave patterns of large enough amplitude or subject to large enough perturbations, both models fail to predict accurately the observed behaviour, which includes frequency downshifting.
Dynamics of sheared inelastic dumbbells
Authors: REDDY K. ANKI , TALBOT J. , KUMARAN V.
Published: August 2010

We study the dynamical properties of the homogeneous shear flow of inelastic dumbbells in two dimensions as a first step towards examining the effect of shape on the properties of flowing granular materials. The dumbbells are modelled as smooth fused disks characterized by the ratio of the distance between centres (L) and the disk diameter (D), with an aspect ratio (L/D) varying between 0 and 1 in our simulations. Area fractions studied are in the range 0.1–0.7, while coefficients of normal restitution (en) from 0.99 to 0.7 are considered. The simulations use a modified form of the event-driven methodology for circular disks. The average orientation is characterized by an order parameter S, which varies between 0 (for a perfectly disordered fluid) and 1 (for a fluid with the axes of all dumbbells in the same direction). We investigate power-law fits of S as a function of (L/D) and (1−en2). There is a gradual increase in ordering as the area fraction is increased, as the aspect ratio is increased or as the coefficient of restitution is decreased. The order parameter has a maximum value of about 0.5 for the highest area fraction and lowest coefficient of restitution considered here. The mean energy of the velocity fluctuations in the flow direction is higher than that in the gradient direction and the rotational energy, though the difference decreases as the area fraction increases, due to the efficient collisional transfer of energy between the three directions. The distributions of the translational and rotational velocities are Gaussian to a very good approximation. The pressure is found to be remarkably independent of the coefficient of restitution. The pressure and dissipation rate show relatively little variation when scaled by the collision frequency for all the area fractions studied here, indicating that the collision frequency determines the momentum transport and energy dissipation, even at the lowest area fractions studied here. The mean angular velocity of the particles is equal to half the vorticity at low area fractions, but the magnitude systematically decreases to less than half the vorticity as the area fraction is increased, even though the stress tensor is symmetric.
Molinism, open theism, and soteriological luck
Authors: ANDERSON MARK B.
Published: August 2010

It is sometimes claimed by open theists that, on Molinism, God controls who is saved and who is damned and that, as a consequence, God's judgement of us is unjust. While this charge is usually lumped under the problem of evil, it could easily be classified under the problem of soteriological luck. I argue that the open theist is impugned by this latter problem. I then show that the Molinist has a solution to both problems and consider objections to that solution.
Aging with Long-term Physical Impairments: The Significance of Social Support
Authors: Casey Rebecca , Stone Sharon Dale
Published: August 2010

Cet article examine les situations de la vie et l’accès à la prise en charge sociale des personnes vivant dans des communautés, qui sont âgés de 50 à 65 ans, et qui ont vécu avec une déficience physique significative depuis plus de 15 ans. Les données ont été recueillies par le biais d’entretiens approfondis et semi-structurés avec huit hommes et femmes. Les conclusions suggèrent que faire façe à la dégradation à long terme peut être une expérience solitaire lorsqu’un individu ne dispose pas d’un réseau solide de la famille et/ou des amis à apporter le soutien émotionnel. Selon les participants, leurs expériences du vieillissment avec déficience à long terme ont été améliorées lorsqu’ils partagent les pensées, les sentiments et les problèmes avec d’autres. Les conclusions montrent également l’importance du genre concernant l’accès à l’assistance sociale, et indiquent l’importance d’utiliser des ententes subjectives pour déterminer le niveau de soutien social disponible aux individus. Plus généralement, les conclusions soulignent que les personnes qui vieillissent avec des déficiences plongent dans, et souhaitent entretenir, des relations réciproques.
Flow Experience in the Daily Lives of Older Adults: An Analysis of the Interaction between Flow, Individual Differences, Serious Leisure, Location, and Social Context
Authors: Heo Jinmoo , Lee Youngkhill , Pedersen Paul M. , McCormick Bryan P.
Published: August 2010

Cette étude a examiné comment les loisirs sérieux, les différences individuelles, le contexte social et l’emplacement contribuent aux expériences de flux – un état psychologique intense – dans la vie quotidienne des adultes plus âgés. La Méthode d’échantillonnage a été utilisée avec 19 adultes plus âgés dans une ville du Midwest des États-Unis. L’expérience de flux a été la mesure des résultats, et les données ont été analysées à l’aide de la modélisation linéaire hiérarchique. Les résultats ont indiqué que la localité et le statut de l’emploi ont influencé l’expérience de flux des sujets. En outre, les conclusions ont révélé que la retraite était négativement liée à la rencontre de flux, et qu’il y avait une association significative entre le domicile et l’expérience de flux. Les résultats de cette étude améliorent la compréhension des expériences de flux dans la vie quotidienne des adultes plus âgés.
Rotavirus genotypes co-circulating in Europe between 2006 and 2009 as determined by EuroRotaNet, a pan-European collaborative strain surveillance network
Authors: ITURRIZA-GÓMARA M. , DALLMAN T. , BÁNYAI K. , BÖTTIGER B. , BUESA J. , DIEDRICH S. , FIORE L. , JOHANSEN K. , KOOPMANS M. , KORSUN N. , KOUKOU D. , KRONEMAN A. , LÁSZLÓ B. , LAPPALAINEN M. , MAUNULA L. , MARQUES A. MAS , MATTHIJNSSENS J. , MIDGLEY S. , MLADENOVA Z. , NAWAZ S. , POLJSAK-PRIJATELJ M. , POTHIER P. , RUGGERI F. M. , SANCHEZ-FAUQUIER A. , STEYER A. , SIDARAVICIUTE-IVASKEVICIENE I. , SYRIOPOULOU V. , TRAN A. N. , USONIS V. , VAN RANST M. , DE ROUGEMONT A. , GRAY J.
Published: August 2010

EuroRotaNet, a laboratory network, was established in order to determine the diversity of co-circulating rotavirus strains in Europe over three or more rotavirus seasons from 2006/2007 and currently includes 16 countries. This report highlights the tremendous diversity of rotavirus strains co-circulating in the European population during three years of surveillance since 2006/2007 and points to the possible origins of these strains including genetic reassortment and interspecies transmission. Furthermore, the ability of the network to identify strains circulating with an incidence of ⩾1% allowed the identification of possible emerging strains such as G8 and G12 since the beginning of the study; analysis of recent data indicates their increased incidence. The introduction of universal rotavirus vaccination in at least two of the participating countries, and partial vaccine coverage in some others may provide data on diversity driven by vaccine introduction and possible strain replacement in Europe.
Multilevel modelling of the prevalence of hospitalized patients infected withPseudomonas aeruginosa
Authors: GBAGUIDI-HAORE H. , CHOLLEY P. , RABAUD C. , BERTRAND X. , TALON D.
Published: August 2010

Pseudomonas aeruginosais one of the leading nosocomial pathogens. The question of the respective contribution of endogenous and exogenous sources remains controversial. In this study, we shed new light on this issue by means of a multilevel logistic regression analysis which allowed a simultaneous investigation of factors associated with prevalence of patients infected withP. aeruginosaat two levels: patient and healthcare facility (HCF) in the eastern regions of France. A total of 25 533 in-patients from 51 HCFs were included in the analysis. The overall prevalence was 0·37% (range 0–1·65%). Multilevel modelling estimated that <14% of total variability of the outcome variable was explained by differences between HCFs and that after adjusting for patient-level variables, which explained 52% of HCF-level variance, the latter became non-significantly different from zero. A compositional effect (patient factors), rather than a contextual effect (ecological factors), explains heterogeneity of the prevalence of patients infected withP. aeruginosain the eastern HCFs of France.
The effects of vitamin C supplementation on incident and progressive knee osteoarthritis: a longitudinal study
Authors: Peregoy Jennifer , Wilder Frances Vaughn
Published: August 2010

Objective

To evaluate the association between vitamin C supplementation and the incidence and progression of radiographic knee osteoarthritis (OA).

Design

Prospective cohort study.

Setting

Clearwater Osteoarthritis Study (COS): (1988 to the present) a longitudinal study.

Subjects

Male and female COS participants aged 40 years and above (n 1023). The study exposure was the participants’ self-reported history of vitamin C supplementation. The participants underwent biennial, sequential knee radiographs, which were assessed using the Kellgren–Lawrence ordinal scale to determine evidence of the study 2 outcomes: incident radiographic knee OA (RKOA) and progression of RKOA.

Results

Individuals without baseline knee OA who self-reported vitamin C supplement usage were 11 % less likely to develop knee OA than were those individuals who self-reported no vitamin C supplement usage (risk ratio (RR) = 0·89, 95 % CI 0·85, 0·93). Among those participants with RKOA at baseline, vitamin C supplement usage did not demonstrate an association with RKOA progression (RR = 0·94, 95 % CI 0·79, 1·22).

Conclusions

In the present prospective cohort study, we found no evidence to support a protective role of vitamin C in the progression of knee OA. However, after controlling for confounding variables, these data suggest that vitamin C supplementation may indeed be beneficial in preventing incident knee OA. Given the massive public health burden of OA, the use of a simple, widely available and inexpensive supplement to potentially reduce the impact of this disease merits further consideration.
Developing a timeline for evaluating public health nutrition policy interventions. What are the outcomes and when should we expect to see them?
Authors: Macdiarmid Jennie I , Loe Jennifer , Douglas Flora , Ludbrook Anne , Comerford Caroline , McNeill Geraldine
Published: August 2010

Objective

To develop a timeline for evaluating public health nutrition policy interventions.

Design

Concept mapping, a stakeholder-driven approach for developing an evaluation framework to estimate the ‘time to impact’ for policy interventions. The Schools (Health Promotion and Nutrition) (Scotland) Act 2007 was used as the model to develop the evaluation timeline as it had typical characteristics of government policy. Concept mapping requires stakeholders to generate a list of the potential outcomes, sort and rate the outcomes. Multidimensional scaling and hierarchical cluster data analysis were used to develop an anticipated timeline to impact for the policy.

Setting

United Kingdom.

Subjects

One hundred and eleven stakeholders representing nutrition, public health, medicine, education and catering in a range of sectors: research, policy, local government, National Health Service and schools.

Results

Eighty-five possible outcomes were identified and grouped into thirteen clusters describing higher-level themes (e.g. long-term health, food literacy, economics, behaviour, diet, education). Negative and unintended consequences were anticipated relatively soon after implementation of the policy, whereas positive outcomes (e.g. dietary changes, health benefits) were thought likely to take longer to emerge. Stakeholders responsible for implementing the legislation anticipated that it would take longer to observe changes than those from policy or research.

Conclusions

Developing an anticipated timeline provides a realistic framework upon which to base an outcome evaluation for policy interventions and identifies positive and negative outcomes as well as considering possible unintended consequences. It offers benefit to both policy makers and researchers in mapping the progress expected towards long-term health goals and outcomes.
The young hard active Sun: soft X-ray irradiation of tryptophan in water solutions
Authors: Ciaravella A. , Bongiorno D. , Cecchi-Pestellini C. , Testa M.L. , Indelicato S. , Barbera M. , Collura A. , La Barbera A. , Mingoia F.
Published: August 2010

The X-ray emission of the young Sun was much harder and intense than today and might have played a significant role in the evolution of complex organics in protoplanetary environments. We investigate the effects of soft X-rays on tryptophan molecules in aqueous solutions at room temperature. As results of the irradiation experiments we detect several light species indicative of fragmentation, together with large molecular structures such as tryptophan dipeptide and tripeptide. Complexification is more evident in H2O solution than in D2O, probably due to isotopic effects. The abundances of peptides depend on the irradiation dose and decrease with increasing energy deposition. Radicals such as D, OD, H and OH, induced by the X-ray interaction with solvents, play a major role in determining the final products.
The behaviour of corporate actors: How much can we learn from the experimental literature?
Authors: ENGEL CHRISTOPH
Published: August 2010

Much of socially relevant behaviour does not originate in isolated individuals. It is embedded in institutional arrangements. Embeddedness can be so pronounced that outsiders no longer focus on the judgement and decision making of individuals contributing to the course of action. Instead, they ascribe the behaviour to the institution, which they refer to as a corporate actor. This social practice makes it meaningful to compare isolated individuals and corporate actors undertaking the same tasks. This paper surveys the empirical literature on the question from experimental economics, social psychology, and organization science.
The close relation between organization theory and Oliver Williamson's transaction cost economics: a theory of the firm perspective
Authors: BAUDRY BERNARD , CHASSAGNON VIRGILE
Published: August 2010

This article deals with the contribution of organization theory to transaction cost economics from an examination of Williamson's theory of the firm. Borrowing and applying some conclusions of organization theory, Williamson rightly differs from other theories of the firm, particularly in his analysis of hierarchical authority, intra-firm conflicts, organizational atmosphere, and the farsighted contracting. Having shed light on the complementary and divergent thoughts of these two different disciplinary approaches to the firm, the article recalls Williamson's project of building a ‘science of organization’.
Crafting analytical tools to study institutional change
Authors: OSTROM ELINOR , BASURTO XAVIER
Published: August 2010

Most powerful analytical tools used in the social sciences are well suited for studying static situations. Static and mechanistic analysis, however, is not adequate to understand the changing world in which we live. In order to adequately address the most pressing social and environmental challenges looming ahead, we need to develop analytical tools for analyzing dynamic situations – particularly institutional change. In this paper, we develop an analytical tool to study institutional change, more specifically, the evolution of rules and norms. We believe that in order for such an analytical tool to be useful to develop a general theory of institutional change, it needs to enable the analyst to concisely record the processes of change in multiple specific settings so that lessons from such settings can eventually be integrated into a more general predictive theory of change.
Pitch angle transport of electrons due to cyclotron interactions with the coherent chorus subelements
Authors: Lakhina G. S. , Tsurutani B. T. , Verkhoglyadova O. P. , Pickett J. S.
Published: August 2010

Chorus is a right‐hand, circularly‐polarized electromagnetic plane wave. Dayside chorus is a bursty emission composed of rising frequency “elements” with duration of ∼0.1 to 1.0 s. Each element is composed of coherent subelements with durations of ∼1 to 100 ms or more. Due to the coherent nature of the chorus subelements/wave packets, energetic electrons with pitch angles near the loss cone may stay in resonance with the waves for more than one wave cycle. The electrons could therefore be “transported” in pitch across a relatively large angle from a single wave‐particle interaction. Here we study the cyclotron resonance of the energetic electron with the coherent chorus subelements. We consider a Gaussian distribution for the time duration of the chorus subelements and derive an expression for the pitch angle transport due to this interaction. For typical chorus subelement parameters, the average pitch angle diffusion coefficients ∼(0.5–8.5) s−1 are found. Such rapid pitch angle scattering may provide an explanation for the ionospheric microbursts of ∼0.1 to 0.5 s in bremsstrahlung x‐rays formed by ∼10–100 keV precipitating electrons. The model is applicable to the cases when R = ttr/Δt = [(ω + Ω/2) ttr/ωτ] > 1 and inhomogeneity factor S = ttr2/tinh2 < 1, where Ω is the electron cyclotron frequency in the ambient magnetic field, B0, ω is the frequency of chorus, ttr is the trapping time (or phase oscillation period), tinh is the time for the passage through the resonance in the inhomogeneous magnetic field, and τ is the duration of the chorus subelement. For the typical parameters at L = 5, the energetic electrons having pitch angles of α ≤ π/3 can satisfy both the condition R > 1 and S < 1 for a range of chorus wave amplitudes.
Magnetic field at geosynchronous orbit during high‐speed stream‐driven storms: Connections to the solar wind, the plasma sheet, and the outer electron radiation belt
Authors: Borovsky Joseph E. , Denton Michael H.
Published: August 2010

Superposed‐epoch analysis is performed on magnetic field measurements from five GOES spacecraft in geosynchronous orbit during 63 high‐speed stream‐driven storms in 1995–2005. The field strength and the field stretching angle are examined as functions of time and local time, and these quantities are compared with the properties of the solar wind, the plasma sheet, and the outer electron radiation belt. Compression of the dayside magnetosphere coincides with an increased solar wind ram pressure commencing before the arrival of the corotating interaction region (CIR). Stretching of the nightside magnetosphere occurs in two phases: a strong‐stretching phase early in the storm followed by a modest‐stretching phase lasting for days. The strong‐stretching phase coincides with the occurrence of the superdense plasma sheet, implying that ion pressure causes the strong stretching. This nightside strong‐stretching perturbation corresponds to a ∼25% contribution to Dst*. The relativistic electron flux at geosynchronous orbit has a dropout recovery temporal profile that matches the strong‐stretching temporal profile; however, the number density dropout and recovery of the electron radiation belt has a profile that leads the stretching profile. A comparison of geosynchronous field strengths and magnetopause field strengths indicates that magnetopause shadowing plays a role in the radiation belt dropout. Temporal fluctuations of the geosynchronous magnetic field are examined via 1 min changes of the GOES magnetic field vectors. Fluctuation amplitudes increase at all local times at storm onset and then slowly decay during the storms. The amplitude is linearly related to the Kp, PCI, and MBI indices, except during the strong‐stretching phase of the storms.
Measuring the effect of local water storage changes on in situ gravity observations: Case study of the Geodetic Observatory Wettzell, Germany
Authors: Creutzfeldt Benjamin , Güntner Andreas , Thoss Heiko , Merz Bruno , Wziontek Hartmut
Published: August 2010

Local water storage changes (WSC) are a key component of many hydrological issues, but their quantification is associated with a high level of uncertainty. High precision in situ gravity measurements are influenced by these WSC. This study evaluates the influence of local WSC (estimated using hydrological techniques) on gravity observations at the Geodetic Observatory Wettzell, Germany. WSC are comprehensively measured in all relevant storage components, namely groundwater, saprolite, soil, topsoil, and snow storage, and their gravity response is calculated. Total local WSC are derived, and uncertainties are assessed. With the exception of snow, all storage components have gravity responses of the same order of magnitude and are therefore relevant for gravity observations. The comparison of the total gravity response of local WSC to the gravity residuals obtained from a superconducting gravimeter shows similarities in both short‐term and seasonal dynamics. A large proportion of the gravity residuals can be explained by local WSC. The results demonstrate the limitations of measuring total local WSC using hydrological methods and the potential use of in situ temporal gravity measurements for this purpose. Nevertheless, due to their integrative nature, gravity data must be interpreted with great care in hydrological studies.
Waveform inversion for S‐wave structure in the lowermost mantle beneath the Arctic: Implications for mineralogy and chemical composition
Authors: Kawai Kenji , Geller Robert J. , Fuji Nobuaki
Published: August 2010

We perform waveform inversion for the radial profile of shear wave velocity in the lowermost mantle beneath the Arctic. We use waveforms from the CANOE (CAnadian NOrthwest Experiment) array, which greatly enhances the resolution in the lowermost mantle as compared to earlier studies. We find a velocity increase at depths from 2500 to 2700 km and a velocity decrease at depths from 2700 km to the core‐mantle boundary (CMB). We interpret the velocity increase as associated with the phase transition from perovskite (pv) to post‐perovskite (ppv), and the velocity decrease as due to a temperature increase in the thermal boundary layer. The shear wave velocity immediately above the core‐mantle boundary (CMB) is 7.11 km/s, while that beneath Central America is 7.25 km/s. This suggests that the proportion of impurities in Mg‐pv or Mg‐ppv beneath the Arctic is 6 mol% larger than that beneath Central America.
Coarse-grained Molecular Dynamics Simulations of Membrane Proteins
Authors: Rouse Sarah , Carpenter Timothy , Sansom Mark S. P.
Published: August 2010

Coarse-grained (CG) models of lipids and proteins are making an increasing impact on molecular dynamics simulations of membrane proteins and peptides. In this chapter we provide a brief introduction to the general methodology for CG MD simulations of biomembranes. We illustrate such simulations via some recent test cases. In particular, these address how CG simulations may be used to explore: (i) the interactions of α-helices with a lipid bilayer; and (ii) the interactions of transmembrane α-helices one another within a lipid bilayer. The latter is of relevance both to modelling of membrane protein folding, and of signalling across membranes by changes in helix oligomerization and/or packing.
Passive Permeation Across Lipid Bilayers: a Literature Review
Authors: Orsi Mario , Essex Jonathan W.
Published: August 2010

The unassisted permeation of molecules through the lipid bilayer is one of the most fundamental biophysical processes characterising biological membranes. Transbilayer permeability is also a crucial property in industrial contexts such as drug design and nanotechnology. The mechanism of solute permeation through membranes is difficult to study experimentally, because of the small scale and complexity of lipid bilayer systems. Computer simulations can help understand permeability processes at the atomic level, and can be applied to quantitatively estimate permeability coefficients. In this review, we summarise the methodology and results of membrane permeability simulations that have been recently reported in the literature.
Implicit Membrane Models For Peptide Folding and Insertion Studies
Authors: Ulmschneider Martin B. , Ulmschneider Jakob P.
Published: August 2010

Accurately predicting the atomic structure of membrane proteins from amino acid sequence remains one of the most important and challenging tasks in biophysics. The chief goal is an efficient method to find the native state in the enormous amount of possible conformations. Recent advances in implicit solvent methodologies have allowed reducing the computational cost of representing the protein environment by several orders of magnitude. This has enabled fully converged molecular mechanics folding simulations of simple membrane proteins. If parameterised well these algorithms allow accurate ab-initio prediction of the native state of small membrane proteins at atomic resolution. Future efforts are underway to extend these methods to simulate the assembly of larger membrane proteins.
Molecular Dynamics Studies of Outer Membrane Proteins: a Story of Barrels
Authors: Khalid Syma , Baaden Marc
Published: August 2010

Outer membrane proteins (OMPs) of Gram-negative bacteria have a variety of functions including passive transport, active transport, catalysis, pathogenesis and signal transduction. Whilst the structures of ∼ 25 OMPs are currently known, the relationship between structure, dynamics and function is often unclear. Furthermore, relatively little is known about the effect of the local environment on the protein dynamics. Over the past 10 years or so, molecular dynamics simulations have been successful in revealing insights into aspects of outer membrane proteins that are difficult to study with experimental methods alone. Indeed in some cases simulations have aided the interpretation of structural data e.g. the apparent discrepancy between the x-ray structure of OmpA from E. coli and the observed conductance data. Simulations have also been employed to design mutants of OMPs with desired properties, e.g mutants of OmpG that may serve as components of stochastic biosensors.

In general, more OMPs have been studied via MD simulations than perhaps any other family of membrane protein, yielding a wealth of information that provides an ideal complement to experimental determined data.
Rhythm versus Rate Control Trials in Atrial Fibrillation
Authors: WYSE D. GEORGE
Published: August 2010

The recent completion of five trials comparing the strategy of rhythm control versus the strategy of rate control in the management of recurrent atrial fibrillation has advanced considerably our understanding of the treatment of this common clinical problem. The background to this research question is outlined, followed by an overview of the five trials and their results. Data on important clinical events from four of the trials are pooled and presented. The aggregate results of the trials do not demonstrate any clear advantage of the rhythm control approach. The findings elevate rate control to the position of an acceptable primary therapy in the types of patients studied and underline the concept that the primary goal of antiarrhythmic therapy for atrial fibrillation at this time is control of symptoms. Under these circumstances, a “safety first” approach is prudent and monitoring for adverse drug effects is mandatory. The results underscore the importance of continuous anticoagulation in patients with stroke risk factors. Finally, the results from these trials help to set the agenda for future research on rhythm management in atrial fibrillation. (J Cardiovasc Electrophysiol, Vol. 14, pp. S35‐S39, September 2003, Suppl.)
Curative Ablation for Atrial Fibrillation:
Authors: SHAH DIPEN
Published: August 2010

In contrast to other supraventricular tachycardias, curative treatment of atrial fibrillation, although increasingly available and rapidly evolving, is neither as effective nor the first choice. Until recently, the unavailability of nonsurgical curative treatment may have fueled a debate on the relative importance of restoring sinus rhythm versus controlling the ventricular rate during atrial fibrillation. Recent randomized trials (PIAF, AFFIRM, and RACE) using very limited atrial fibrillation burden assessment show that pharmacologic ventricular rate control is much safer and possibly more effective than pharmacologic restoration of sinus rhythm. A clinical trial comparing a truly curative treatment of atrial fibrillation—such as catheter ablation targeting pulmonary vein isolation—with pharmacologic treatment is required. It should focus on reliable efficacy parameters, use vigilant assessment of safety, and, most importantly, be structured to provide all‐important prognostic information on long‐term outcome. Atrial fibrillation burden is a theoretically robust efficacy parameter, but accurate quantification over a sufficiently long period of monitoring will require technologically innovative noninvasive rhythm monitoring devices. (J Cardiovasc Electrophysiol, Vol. 14, pp. S48‐S51, September 2003, Suppl.)
Abnormal Sinus Node Function in Clinical Arrhythmias
Authors: SCHUESSLER RICHARD B.
Published: August 2010

Abnormal Sinus Node Function. To understand abnormal sinus node function in clinical atrial arrhythmias, it is essential to understand the normal function of the sinus node. Much of our understanding of the sinus node comes from work done in rabbits. In small animals, the node is a thin structure and can be modeled in two dimensions. However, in canines and humans, the node is a more complex structure completely surrounded by myocytes. Recent data suggest that the node may be insulated from the surrounding atrial myocytes, except at a limited number of exit sites. A model of the node with discrete exit sites explains how atrial activation can be initiated from multiple sites simultaneously. Within the node there may exist specialized pathways that explain the complex conduction within the node. Multiple cell types, with different intrinsic rates, combined with the nonuniform distribution of autonomic receptors, provide a basis for understanding the dynamics of heart rate control and the initiation of atrial activation. In addition, this model of the sinus node provides a framework to propose novel mechanisms underlying various atrial arrhythmias, such as atrial premature depolarizations or sinus node reentry. (J Cardiovasc Electrophysiol, Vol. 14, pp. 215‐217, February 2003)
Clinical Investigation of a New Dual‐Chamber Implantable Cardioverter Defibrillator with Improved Rhythm Discrimination Capabilities
Authors: BAILIN STEVEN J. , NIEBAUER MARK , TOMASSONI GERY , LEMAN ROBERT ,   The Photon Investigators
Published: August 2010

New ICD with Improved Rhythm Discrimination.
Introduction: Despite continuing advances, inappropriate implantable cardioverter defibrillator (ICD) therapies in response to nonventricular tachyarrhythmias continue to cause patient discomfort and increased follow‐up demands.

Methods and Results: We investigated the performance of a new dual‐chamber ICD (Photon DR, St. Jude Medical), with specific attention to its arrhythmia discrimination and detection capabilities. The system uses a hierarchical approach to tachyarrhythmia classification utilizing a new AV Rate Branch feature and subsequently utilizing morphology analysis, onset, and stability criteria. The arrhythmia discrimination results from this study group were compared to historical control group data from a recent clinical investigation of single‐chamber Contour MD (Morphology Discrimination) and Angstrom MD ICDs without the Rate Branch feature. Rhythm discrimination was evaluated by comparing ventricular tachycardia diagnosis sensitivity and specificity between the two groups. To determine whether the new discrimination scheme affected detection speed, median ventricular fibrillation (VF) detection and redetection times also were compared. The study group consisted of 107 patients, and the control group consisted of 161 patients. Use of the AV Rate Branch feature was associated with significant improvements in both sensitivity (100% vs 97.9%, P < 0.0001) and specificity (84% vs 55.7%, P = 0.0002) of ventricular tachycardia diagnosis. Use of the new scheme slightly but significantly accelerated VF detection times (2.8 vs 3.0 sec, P < 0.0001) and redetection times (1.3 vs 1.4 sec, P < 0.0001). Adverse events were typical for this patient population.

Conclusion: Compared with earlier St. Jude Medical ICDs, the Photon DR ICD offers improved rhythm discrimination without compromising VF detection time. (J Cardiovasc Electrophysiol, Vol. 14, pp. 144‐149, February 2003)
Concealed Left Anterior Accessory Pathways:
Authors: TADA HIROSHI , NAITO SHIGETO , TANIGUCHI KOICHI , NOGAMI AKIHIKO
Published: August 2010

Concealed Left Anterior Accessory Pathway. Left anterior accessory pathways are considered to occur rarely because the junction between the aortic and mitral valve areas represents a fibrous continuity. Of 207 patients with concealed left accessory pathways in whom catheter ablation was performed at our institution over the past 8 years, two patients had concealed left anterior accessory pathways. The polarity of the retrograde P waves was positive in the inferior leads and negative in leads I and aVL during orthodromic reciprocating tachycardia. Complete elimination of accessory pathway conduction was achieved using a transseptal approach or with radiofrequency energy application from the left sinus of Valsalva. (J Cardiovasc Electrophysiol, Vol. 14, pp. 204‐208, February 2003)
Incessant Supraventricular Tachycardia with Constant 1:2 Atrioventricular Ratio:
Authors: KIRCHHOF PAULUS , LOH PETER , RIBBING MICHAEL , WASMER KRISTINA
Published: August 2010

We report a patient with incessant, exercise‐limiting supraventricular tachycardia on the ventricular level and a constant 1:2 atrioventricular relation. Careful mapping of the AV nodal region revealed His alternans in the inferior AV nodal area and nonalternating His morphologies in the superior His region. Radiofrequency catheter ablation in the inferior AV node cured the patient (11‐month follow‐up). Constant dual ventricular activation, His alternans, distinct His morphologies in the superior and inferior His, and long‐term suppression of the tachycardia by ablation in the so‐called slow pathway region of the AV node are suggestive of permanent dual anterograde AV nodal conduction in this patient.
(J Cardiovasc Electrophysiol, Vol. 14, pp. 316‐319, March 2003)
“Double” Potentials Define Linear Lesion Conduction Block Using A Novel Mapping/Linear Lesion Ablation Catheter
Authors: MORGAN JOHN M. , HAYWOOD GUY , SCHIRDEWAN ALEXANDER , BRUGADA PEDRO , GEELEN PETER , MEYERFELDT UDO , ROBERTS PAUL , GIBSON CHUCK
Published: August 2010

Introduction: A novel mapping/ablation catheter using a coaxially ablation electrode (E) that is moveable between distal and proximal ring electrodes along its shaft was used to create a linear lesion over the cavotricuspid isthmus (CTI) and bidirectional block in 32 patients (21 men; age 38–79 years) undergoing ablation for counterclockwise atrial flutter.

Methods and Results: Two bipolar electrograms (E1 and E2) were recorded: between E and the distal ring electrode and between E and the proximal ring electrode. Interpole distance varied for both as the E traversed the slide shaft. Given the catheter's concept, these bipoles are orientated exactly along the line of lesion creation. Prior to ablation, unitary bipolar electrograms were recorded along the catheter slide shaft position. As the CTI lesion was created (E moved along the catheter slide shaft in 2‐mm steps with radiofrequency energy delivered to achieve 65°C for 60 sec at each), double potentials (DP) were observed. Interpotential distance became maximal with completion of the linear lesion and bidirectional block. DPs were noted in all these procedures. With pacing from the low septal right atrium at bidirectional block creation, interpotential timing was

140.9 ± 15 msec

and from the low right atrial free wall was

145.13 ± 18 msec.

In sinus rhythm, DP interpotential timing was less

(35.13 ± 9 msec)

as activation fronts arrived from both septal and anterior atrial aspects.

Conclusion: Bipolar recordings from the coaxially moveable electrode catheter provide unique electrogram data. DPs recorded during and after linear lesion creation can define conduction block across that lesion without the need for additional mapping catheters or complex mapping technology.
(J Cardiovasc Electrophysiol, Vol. 14, pp. 236‐242, March 2003)
Vortex Cordis as a Mechanism of Postshock Activation:
Authors: ASHIHARA TAKASHI , NAMBA TSUNETOYO , YAO TAKENORI , OZAWA TOMOYA , KAWASE AYAKA , IKEDA TAKANORI , NAKAZAWA KAZUO , ITO MAKOTO
Published: August 2010

Introduction: The ventricular apex has a helical arrangement of myocardial fibers called the “vortex cordis.” Experimental studies have demonstrated that the first postshock activation originates from the ventricular apex, regardless of the electrical shock outcome; however, the related underlying mechanism is unclear. We hypothesized that the vortex cordis contributes to the initiation of postshock activation. To clarify this issue, we numerically studied the transmembrane potential distribution produced by various electrical shocks.

Methods and Results: Using an active membrane model, we simulated a two‐dimensional bidomain myocardial tissue incorporating a typical fiber orientation of the vortex cordis. Monophasic or biphasic shock was delivered via two line electrodes located at opposite tissue borders. Transmembrane potential distribution during the monophasic shock at the center of the vortex cordis showed a gradient high enough to initiate postshock activation. The postshock activation from the center of the vortex cordis was not suppressed, regardless of the initiation of spiral wave reentry. Spiral wave reentry was induced by the monophasic shock when the center area of the vortex cordis was partially excited by the nonuniform virtual electrode polarization. Postshock activation following the biphasic shock also originated from the center of the vortex cordis, but it tended to be suppressed due to the narrower excitable gap around the center of the vortex cordis. The electroporation effect, which was maximal at the center of the vortex cordis, is another possible mechanism of postshock activation.

Conclusion: Our simulations suggest that the vortex cordis may cause postshock activation.
(J Cardiovasc Electrophysiol, Vol. 14, pp. 295‐302, March 2003)
Effect of Atrial Fibrillation Duration on Probability of Immediate Recurrence after Transthoracic Cardioversion
Authors: ORAL HAKAN , OZAYDIN MEHMET , STICHERLING CHRISTIAN , TADA HIROSHI , SCHARF CHRISTOPH , CHUGH AMAN , LAI STEVE W.K. , PELOSI FRANK , KNIGHT BRADLEY P. , STRICKBERGER S. ADAM , MORADY FRED
Published: August 2010

Immediate Recurrence of Atrial Fibrillation. Introduction: An immediate recurrence of atrial fibrillation (IRAF) appears to be more common after early restoration of sinus rhythm with an implantable atrial defibrillator than after elective transthoracic cardioversion, which suggests that the probability of IRAF may be related to the duration of AF.

Methods and Results: Transthoracic cardioversion was performed 85 ± 187 days (range 7 minutes to 8 years) after the onset of atrial fibrillation in 315 patients (mean age 61 ± 13 years). IRAF was defined as a recurrence of AF within 60 seconds after restoration of sinus rhythm. IRAF occurred in 56% of patients when cardioversion was performed within 1 hour of the onset of AF compared with 12% of patients when cardioversion was performed after 24 hours of AF (P < 0.001). The duration of AF was the only independent predictor of IRAF among the clinical variables of age, gender, structural heart disease, antiarrhythmic drug therapy, and cardioversion energy (P < 0.01).

Conclusion: IRAF is more likely to occur when the duration of AF is <1 hour than when the duration is >24 hours. This observation has clinical implications for the most appropriate timing of cardioversion, particularly in patients who receive device therapy for AF. (J Cardiovasc Electrophysiol, Vol. 14, pp. 182‐185, February 2003)
Variable Patterns of Septal Activation in Patients with Left Bundle Branch Block and Heart Failure
Authors: RODRIGUEZ LUZ‐MARIA , TIMMERMANS CARL , NABAR ASHISH , BEATTY GRAYDON , WELLENS HEIN J.J.
Published: August 2010

Septal Activation in Patients with LBBB and Heart Failure.
Introduction: Little is known about the septal activation pattern in patients with heart failure and left bundle branch block (LBBB‐HF).

Methods and Results: The right ventricular (RV) and left ventricular (LV) activation patterns of 12 patients (mean age 67 ± 11 years) with LBBB‐HF and 5 patients (mean age 45 ± 14) with normal hearts were studied during sinus rhythm using a three‐dimensional mapping system. The etiology of HF was myocardial infarction (n = 4) or idiopathic dilated cardiomyopathy (n = 8). In patients with LBBB‐HF, endocardial activation usually started before the onset of the surface QRS complex on the RV free wall. Latest RV activation occurred in the basal region, and total RV activation time was longer than in patients with normal hearts. In patients with LBBB‐HF, the left septum was activated via slowly conducting LBB or via right‐to‐left transseptal conduction. In both patients with LBBB‐HF and those with normal hearts, latest LV activation occurred either in the posterior or posterolateral‐basal region. Conduction velocity was slower in the peri‐scar region, in patients with previous myocardial infarct and globally slow, in patients with idiopathic dilated cardiomyopathy.

Conclusion: The two types of left septal activation observed in patients with LBBB‐HF may have consequences for biventricular hemodynamic performance. Conduction slowing along the LV, regionally or globally, suggests a contribution outside the specific conduction system in the ECG pattern of LBBB. (J Cardiovasc Electrophysiol, Vol. 14, pp. 135‐141, February 2003)