bluuebunny/crossref_metadata_2025 huggingface dataset:
Saturn's magnetodisc current sheet
Authors: Arridge C. S. , Russell C. T. , Khurana K. K. , Achilleos N. , Cowley S. W. H. , Dougherty M. K. , Southwood D. J. , Bunce E. J.
Published: April 2008

Pioneer 11 observations from the dawn flank of Saturn's magnetosphere provided evidence for a thin equatorial current sheet. Magnetometer data from the Cassini orbiter have also revealed the presence of this current sheet and shown it to be a consistent feature of the dawn flank. Arridge et al. (2007) recently investigated the stress balance in this current sheet and showed that the centrifugal force dominated the mechanical stresses beyond a radial distance of 20–30 RS from Saturn. These observations led Arridge et al. (2007) to interpret this current sheet as a magnetodisc, similar to that in the jovian magnetosphere but strongly asymmetric in local time. In this paper we present a survey of these thin current sheets in Saturn's magnetosphere and show that they have been observed at all local times where Cassini has explored the outer magnetosphere beyond 15 RS. We interpret the observations as evidence for Saturn's magnetodisc current sheet and show that under certain conditions the magnetodisc is not as asymmetric as Arridge et al. (2007) first suggested. Under low solar wind dynamic pressures where the subsolar magnetopause standoff distance is >23 RS, Saturn's ring current dominates over Saturn's internal field and produces a magnetodisc. Under compression the dayside field becomes more dipolar and the magnetodisc is only present on the nightside and flanks of the magnetosphere. Hence in contrast to Jupiter's magnetodisc, the kronian magnetodisc is highly sensitive to the upstream solar wind conditions. We also present theoretical stress balance calculations supporting the existence of a magnetodisc at Saturn, where we show that the centrifugal force is plausibly sufficient to produce the observed magnetodisc.
Comparison of periodic substorms at Jupiter and Earth
Authors: Kronberg E. A. , Woch J. , Krupp N. , Lagg A. , Daly P. W. , Korth A.
Published: April 2008

The Energetic Particles Detector and magnetometer measurements on Galileo showed that the Jovian magnetosphere undergoes reconfiguration processes which are very similar to the characteristics of a terrestrial substorm. At Jupiter the reconfiguration process occurs quasi‐periodically with a repetition period of several days. In the terrestrial magnetosphere periodic substorms have been observed during magnetic storms. The comparison of the periodic magnetospheric disturbances at Jupiter and Earth shows that they are similar in dynamic features as well as in spatial distribution but have different energy sources. In the case of Earth, the well‐established energy source is the solar wind. In the case of the Jovian magnetosphere, it is believed that internal energy is supplied by the fast planetary rotation and the moon Io which releases ∼1000 kg s−1 of plasma into the magnetosphere. It is established that the energy accumulation and subsequent release lead to similar features in the magnetospheres of both planets. The particle data show periodic intensity fluctuations and plasma pressure variations. In addition, recurring signatures of stretching and dipolarization are observed in the magnetic field at the terrestrial and Jovian magnetospheres. Furthermore, the release process is associated with an intensification of auroral emissions. The typical phases for terrestrial substorms like growth, expansion and recovery are also found in the periodic substorms at Jupiter. As a lesson taken from the Jovian magnetosphere it is proposed that under certain conditions periodic magnetospheric substorms at Earth can be driven by mass‐loading from the plasmasphere.
Spatial and interannual variability in mesoscale circulation in the northern California Current System
Authors: Keister Julie E. , Strub P. Ted
Published: April 2008

We used wavelet analyses of sea surface height (SSH) from >13 years of satellite altimeter data to characterize the variability in mesoscale circulation in the northern California Current (35°N–49°N) and explore the mechanisms of variability. We defined “mesoscale” circulation as features, such as eddies and filaments, which have 50‐ to 300‐km length scales and 4‐ to 18‐week temporal scales. Fluctuations in SSH caused by such features were reflected in wavelet analyses as power (energy). Spatial and interannual variation in mesoscale energy was high. Energy was highest at ∼38°N, decreasing to the north and south. Between ∼43°N and 48°N, energy was low. Zonally, mesoscale energy was highest between ∼125°W and 129°W at latitudes south of 44°N; very little power occurred in the deep ocean west of 130°W. Energy peaked during summer/fall in most years. The primary climate signals were suppressed energy during La Niña and cold years and increased energy during El Niño events. Energy was not strongly linked to upwelling winds, but did correspond to climate indices, indicating that basin‐scale processes play a role in controlling mesoscale circulation. We hypothesize that climate affects mesoscale energy through changes in both potential and kinetic energy in the form of density gradients and coastal upwelling winds. The relationship between mesoscale circulation and climate was complex: no single climate, transport, or upwelling index explained the variability. These results are relevant to ecosystem dynamics and the global carbon cycle because mesoscale circulation features deliver nutrient‐rich water and coastal organisms from productive upwelling areas to the deep sea.
A multistart weight‐adaptive recursive parameter estimation method
Authors: Pauwels Valentijn R. N.
Published: April 2008

The determination of the parameters for hydrologic models has been the subject of a large number of studies during the last 3 decades. A multitude of methods have been developed for this purpose. Generally, the mismatch between the model simulations and the observations is lumped into an objective function, which is then is optimized by these methods. This can lead to parameter values that result in a good model performance under certain (e.g., low flow) conditions but not under other (e.g., high flow) conditions. The objective of this paper is to demonstrate a calibration algorithm which leads to a good model performance under all boundary conditions. This algorithm is referred to as Multistart Weight‐Adaptive Recursive Parameter Estimation (MWARPE). For this purpose the equations of the Extended Kalman Filter (EKF) have been used recursively in a Monte‐Carlo approach, strongly increasing the chance that a globally optimal parameter set is obtained instead of a local optimum. The method has been applied to a rainfall‐runoff model for the Zwalm catchment in Belgium, using a 1‐year, a 2‐year, and a 3‐year calibration period. The results have been compared to the Shuffled Complex Evolution (SCE)‐UA method. A synthetic study revealed that for narrow parameter limits the SCE‐UA algorithm outperformed MWARPE, while for broad parameter limits the opposite occurred. For the test case using in situ observed data, the SCE‐UA method resulted in slightly lower RMSE values than MWARPE, but MWARPE performed better outside the calibration period. It has been found that MWARPE can bypass local optima in the determination of the final parameter set. Also, the best initial parameter sets (with the lowest RMSE) do not lead to the best final parameter values. To apply the method only four parameters need to be specified, more specifically the number of starting points, the number of iterations per starting point, one parameter used to initialize the model error covariance matrix, and the observation error. For this reason, the method could be a simple alternative to more complex methods if model parameters have to be determined when time and/or computational power are limited.
Drainage hydraulics of permeable friction courses
Authors: Charbeneau Randall J. , Barrett Michael E.
Published: April 2008

This paper describes solutions to the hydraulic equations that govern flow in permeable friction courses (PFC). PFC is a layer of porous asphalt approximately 50 mm thick that is placed as an overlay on top of an existing conventional concrete or asphalt road surface to help control splash and hydroplaning, reduce noise, and enhance quality of storm water runoff. The primary objective of this manuscript is to present an analytical system of equations that can be used in design and analysis of PFC systems. The primary assumptions used in this analysis are that the flow can be modeled as one‐dimensional, steady state Darcy‐type flow and that slopes are sufficiently small so that the Dupuit‐Forchheimer assumptions apply. Solutions are derived for cases where storm water drainage is confined to the PFC bed and for conditions where the PFC drainage capacity is exceeded and ponded sheet flow occurs across the pavement surface. The mathematical solutions provide the drainage characteristics (depth and residence time) as a function of rainfall intensity, PFC hydraulic conductivity, pavement slope, and maximum drainage path length.
A unifying framework for particle entrainment
Authors: Coleman S. E. , Nikora V. I.
Published: April 2008

A new framework is presented that describes the hydrodynamic entrainment of sediments. The framework is derived from the general equations of particle stability and fluid motion and covers a wide range of scales, from that of the individual particle to en masse entrainment at the scale of the stream reach. Particle entrainment is explicitly shown to be driven by the combination of instantaneous fluid stress and pressure gradients, particle surface contact forces, particle submerged weight, and the weight and motion of particle‐associated fluid. Of these factors, bed shear stresses, across‐particle differences in pressures and fluxes of momentum, and sediment bed characteristics are found to be key factors in particle entrainment. The conventional Shields entrainment parameter is shown to be applicable to averaged en masse entrainment by steady uniform 2‐D flows. This nondimensionalized bed shear stress at threshold is further demonstrated to be a function of interparticle forces and bed normal hydrodynamic forces, and thereby sediment size and other fluid, sediment and bed characteristics. Observed Shields parameter dependencies are discussed. The presented framework, which includes all relevant particle and fluid characteristics and flow dynamics, may aid understanding of entrainment mechanics, the design and analysis of further studies of entrainment, the design of parameterizations that lead to the solution of entrainment problems, and numerical modeling of combined fluid and sediment dynamics.
Characterization of a low-molecular-mass stimulator protein of Mg2+-independent Ca2+-ATPase: effect on phosphorylation/dephosphorylation, calcium transport and sperm-cell motility
Authors: Ghoshal Srabasti , Sengupta Tanusree , Dundung Sandhya R. , Majumder Gopal C. , Sen Parimal C.
Published: April 2008

A 14 kDa cytosolic protein purified from bovine brain homogenate has been recently reported as a stimulator of goat spermatozoa Mg2+-independent Ca2+-ATPase. In the present study, we demonstrate the formation of the [γ-32P]ATP-labelled phosphoenzyme as the 110 kDa phosphoprotein and its rapid decomposition in presence of the stimulator protein. Together with the cross-reactivity of this 110 kDa protein with an anti-SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) 2a antibody, the ATPase can now be conclusively said to belong to the SERCA family, which is activated by the stimulator. The ability of the stimulator to enhance the Ca2+ transport has been elucidated from 45Ca2+ uptake studies and was found to be sensitive to Ca2+ channel blockers. CD revealed an α-helical structure of the stimulator. The amino acid analysis suggests that it is composed primarily of hydrophobic and some acidic amino acid residues. The pI of 5.1 has been re-confirmed from two-dimensional electrophoresis. Immuno-cross-reactivity studies indicate that the stimulator or similar proteins are present in cytosolic fractions of liver, kidney or testes in different species, but brain is the richest source. Proteomic analyses of its trypsinized fragments suggest its similarity with bovine THRP (thyroid hormone-responsive protein). The physiological significance of the stimulator has been suggested from its ability to activate sperm-cell motility.
Direct spectroscopic evidence of self-formed C60 inclusions in fullerenelike hydrogenated carbon films
Authors: Buijnsters J. G. , Camero M. , Gago R. , Landa-Canovas A. R. , Gómez-Aleixandre C. , Jiménez I.
Published: April 2008

The detection of self-formed C60 inclusions in hydrogenated carbon (C:H) with fullerenelike (FL) structure is reported. This material is synthesized by bias-enhanced electron cyclotron resonance chemical vapor deposition at low substrate temperatures (<120°C). The FL structure is identified by high-resolution transmission electron microscopy whereas the presence of C60 inclusions is derived from spectral signatures in the C(1s) x-ray absorption near edge structure. The formation of FL-C:H takes place for negative bias voltages higher than 100V, in parallel with dehydrogenation and drastic improvement of the tribomechanical film properties.
Hybridized surface plasmon polaritons at an interface between a metal and a uniaxial crystal
Authors: Li Rui , Cheng Chen , Ren Fang-Fang , Chen Jing , Fan Ya-Xian , Ding Jianping , Wang Hui-Tian
Published: April 2008

The surface plasmon polariton (SPP) at an interface between a metal and a uniaxial crystal is studied. A new class of hybridized SPP found in this work is quite different from the traditional SPP at the interface between a metal and an isotropic dielectric. In contrast to the two evanescent fields for the traditional SPP, the hybridized SPP involves four evanescent fields: transverse-electric-like and transverse-magnetic-like waves in the metal, and ordinary-light-like and extraordinary-light-like waves in the uniaxial crystal. The necessary conditions and the regimes for the existence of the hybridized SPP are presented. Some potential applications are also discussed.
Properties of InAs metal-oxide-semiconductor structures with atomic-layer-deposited Al2O3 Dielectric
Authors: Li Ning , Harmon Eric S. , Hyland James , Salzman David B. , Ma T. P. , Xuan Yi , Ye P. D.
Published: April 2008

InAs is very attractive as a channel material for high-speed metal-oxide-semiconductor (MOS) field-effect transistors due to its very high electron mobility and saturation velocity. We investigated the processing conditions and the interface properties of an InAs metal-oxide-semiconductor structure with Al2O3 dielectric deposited by atomic-layer deposition. The MOS capacitor I-V and C-V characteristics were studied and discussed. Simple field-effect transistors fabricated on an InAs bulk material without source/drain implantation were measured and analyzed.
Isomorphous substitution of AlPO4-5: A density functional study
Authors: Liu H. J. , Wen Y. W. , Miao L. , Shi J.
Published: April 2008

Using density functional calculations, we study the isomorphous substitution of AlPO4-5 crystal inside which the 4Å single-walled carbon nanotubes are fabricated. A series of elements from the Periodic Table (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg, and Si) are introduced into the framework to replace the Al or P. The formation energies of nanotubes and the corresponding electronic properties are discussed and compared. It is found that the incorporation of Zn, Mg, Si, and Cu are very favorable for the formation of carbon nanotubes, while there is less or no effect for other investigated elements.
Growth of atomically flat nanofilms and surface superstructures of intrinsic liquid alloys
Authors: Yamanaka Toshiro , Wang Jian-Li , Nagao Tadaaki , Yaginuma Shin , Liu Canhua , Tupkalo Andrey V. , Sakurai Toshio
Published: April 2008

Atomically flat nanofilms were formed during growth of Ga on a Si(111) surface using an In surfactant above the melting point of Ga (and In–Ga eutectic) throughout Ga coverages of 0.17 to 5 monolayers (0.17⩽ΘGa⩽5). Unique superstructures such as a quasisquare-lattice (QS) structure at ΘGa=3 to 4 and a 5×5 structure at ΘGa=5 appeared as ΘGa increased. The QS structure had Ga dimer layers similar to the square lattices of an alpha-Ga(100) plane but also maintained the 1×1 structure of Si(111). As dimer layers transformed into a monoatomic layer, QS transformed into a 5×5 structure that no longer has square features.
Uterine crowding in the sow affects litter sex ratio, placental development and embryonic myogenin expression in early gestation
Authors: Tse W.-Y. , Town S. C. , Murdoch G. K. , Novak S. , Dyck M. K. , Putman C. T. , Foxcroft G. R. , Dixon W. T.
Published: April 2008

Uterine crowding in the pig results in intrauterine growth restriction (IUGR), and permanently affects fetal muscle fibre development, representing production losses for the commercial pig herd. The present study sought to understand how different levels of uterine crowding in sows affects muscle fibre development in the early embryo at the time of muscle fibre differentiation and proliferation. Sows either underwent surgical, unilateral oviduct ligation (LIG; n = 10) to reduce the number of embryos in the uterus, or remained as intact, relatively-crowded controls (CTR; n = 10). Embryos and placentae were collected at Day 30 of gestation, and myogenic regulatory factor (MRF) transcript abundance was determined using real-time PCR for both myogenin (MYOG) and myoblast differentiation 1 (MYOD1). Unilateral tubal ligation resulted in lower numbers of embryos in utero, higher placental weights and a higher male : female sex ratio (P < 0.05). Relative MYOD1 expression was not different, but MYOG expression was higher (P < 0.05) in the LIG group embryos; predominantly due to effects on the male embryos. Relatively modest uterine crowding therefore affects MRF expression, even at very early stages of embryonic development, and could contribute to reported differences in fetal muscle fibre development, birthweight and thus post-natal growth performance in swine.
Variable sperm size and motility activation in the pipefish, Syngnathus abaster; adaptations to paternal care or environmental plasticity?
Authors: Dzyuba B. B. , Van Look K. J. W. , Kholodnyy V. S. , Satake N. , Cheung S. , Holt W. V.
Published: April 2008

Like seahorses, some of the closely-related pipefish species (Family Syngnathidae) incubate their eggs within a male brood pouch. This has contributed to considerable confusion about sperm transfer mechanisms to the eggs; some authors have reported that ejaculates are released directly into water before they reach the eggs, while others have suggested that eggs are fertilised using spermatozoa deposited directly into the brood pouch via an internal sperm duct. Here we present anatomical evidence from the freshwater pipefish, Syngnathus abaster, showing not only that direct sperm deposition into the pouch is impossible, but that spermatozoa must somehow travel a significant distance (>4 mm) outside the body of the male, to reach and fertilise eggs in the pouch. We have also used several putative sperm-activating solutions to identify the type of environment most conducive to sperm activation. Spermatozoa released from the testis were active for a brief period (<5 min) in water or 150 mm saline, but showed prolonged (>25 min) motility in ovarian fluid. This suggests that spermatozoa are released into a mixture of ovarian fluid and eggs while the male and female are in close contact. Our data also suggest that the fertilisation mechanism is highly efficient (sperm : egg ratio <200 : 1) even though this pipefish species produces dimorphic spermatozoa (with long and short flagellae). The shorter (<40 μm) morphotypes were not capable of motility activation, and are therefore probably incapable of fertilisation. If so, the sperm : egg ratio reported here would represent an overestimate.
The Politics of Identity in Post-Soviet Abkhazia: Managing Diversity and Unresolved Conflict1
Authors: Clogg Rachel
Published: April 2008

The question of ethnic and national identity has dominated post-Soviet life in Abkhazia, which is situated on the Black Sea coast, in the north-west corner of the South Caucasus. Formerly an Autonomous Soviet Socialist Republic within the Georgian Soviet Socialist Republic, its status is now contested. Following violent armed conflict with Georgia over a period of 13 months in 1992/1993, Abkhazia becamede factoindependent. However, while not now under Georgian control, Abkhazia remainsde jurepart of the Republic of Georgia, which considers Abkhazia an integral component of its state. Abkhazia declared independence in 1999, a status that remains unrecognized by the international community.
ECRH power deposition from a quasi-optical point of view
Authors: Balakin A.A. , Balakina M.A. , Westerhof E.
Published: April 2008

A quasi-optical description of the propagation and damping of the slowly varying wave amplitude across an arbitrary electron cyclotron wave beam is presented. This model goes well beyond those implemented in existing beam tracing codes, which typically require the spatial inhomogeneity across the wave beam to be small. The present model allows an accurate description of the wave beam evolution in the region of electron cyclotron power deposition, where the latter condition is quite generally broken. The additional physical effects from spatial inhomogeneity and dispersion included in the quasi-optical model are discussed in relation to their consequences for the power deposition profile. Quite generally, a broader power deposition profile is obtained in the quasi-optical calculations. The importance of these effects is analysed in a number of scans varying the injection geometry for typical conditions in both the ITER and the TEXTOR tokamak. Optimization of the power deposition profile towards a minimal width is found to require a focused wave beam with a waist of typically 2 cm width localized near the electron cyclotron resonance region. Calculations are also presented for beams injected from the ITER Upper Port electron cyclotron resonance heating (ECRH) launcher as it is currently being designed. These show that the additional power deposition profile broadening from quasi-optical effects may result in a drop in the predicted efficiency for neoclassical tearing mode or sawtooth control by up to a factor of 2.
Cooling of a micro-mechanical resonator by the back-action of Lorentz force
Authors: Wang Ying-Dan , Semba K , Yamaguchi H
Published: April 2008

Using a semi-classical approach, we describe an on-chip cooling protocol for a micro-mechanical resonator by employing a superconducting flux qubit. A Lorentz force, generated by the passive back-action of the resonator's displacement, can cool down the thermal motion of the mechanical resonator by applying an appropriate microwave drive to the qubit. We show that this on-chip cooling protocol, with well-controlled cooling power and a tunable response time of passive back-action, can be highly efficient. With feasible experimental parameters, the effective mode temperature of a resonator could be cooled down by several orders of magnitude.
Simple is beautiful: a straightforward approach to improve the delineation of true and false positives in PSI-BLAST searches
Authors: Lee Marianne M. , Chan Michael K. , Bundschuh Ralf
Published: April 2008

Motivation: The deluge of biological information from different genomic initiatives and the rapid advancement in biotechnologies have made bioinformatics tools an integral part of modern biology. Among the widely used sequence alignment tools, BLAST and PSI-BLAST are arguably the most popular. PSI-BLAST, which uses an iterative profile position specific score matrix (PSSM)-based search strategy, is more sensitive than BLAST in detecting weak homologies, thus making it suitable for remote homolog detection. Many refinements have been made to improve PSI-BLAST, and its computational efficiency and high specificity have been much touted. Nevertheless, corruption of its profile via the incorporation of false positive sequences remains a major challenge.

Results: We have developed a simple and elegant approach to resolve the problem of model corruption in PSI-BLAST searches. We hypothesized that combining results from the first (least-corrupted) profile with results from later (most sensitive) iterations of PSI-BLAST provides a better discriminator for true and false hits. Accordingly, we have derived a formula that utilizes the E-values from these two PSI-BLAST iterations to obtain a figure of merit for rank-ordering the hits. Our verification results based on a ‘gold-standard’ test set indicate that this figure of merit does indeed delineate true positives from false positives better than PSI-BLAST E-values. Perhaps what is most notable about this strategy is that it is simple and straightforward to implement.

Contact:  bundschuh@mps.ohio-state.edu
Electromagnetic fields in the presence of an infinite metamaterial wedge
Authors: Salem Mohamed A , Kamel Aladin H
Published: April 2008

Electromagnetic fields, excited by an electric line source in the presence of an infinite metamaterial wedge, are determined by application of the Kontorovich–Lebedev transform. Uncoupled singular integral equations for the spectral functions are derived and a numerical scheme is devised and implemented to solve them. Numerical results showing the influence of a metamaterial wedge presence on the directivity of a line source are presented and verified through finite-difference frequency-domain simulations.
Insights from the complete genome sequence of Mycobacterium marinum on the evolution of Mycobacterium tuberculosis
Authors: Stinear Timothy P. , Seemann Torsten , Harrison Paul F. , Jenkin Grant A. , Davies John K. , Johnson Paul D.R. , Abdellah Zahra , Arrowsmith Claire , Chillingworth Tracey , Churcher Carol , Clarke Kay , Cronin Ann , Davis Paul , Goodhead Ian , Holroyd Nancy , Jagels Kay , Lord Angela , Moule Sharon , Mungall Karen , Norbertczak Halina , Quail Michael A. , Rabbinowitsch Ester , Walker Danielle , White Brian , Whitehead Sally , Small Pamela L.C. , Brosch Roland , Ramakrishnan Lalita , Fischbach Michael A. , Parkhill Julian , Cole Stewart T.
Published: April 2008

Mycobacterium marinum, a ubiquitous pathogen of fish and amphibia, is a near relative of Mycobacterium tuberculosis, the etiologic agent of tuberculosis in humans. The genome of the M strain of M. marinum comprises a 6,636,827-bp circular chromosome with 5424 CDS, 10 prophages, and a 23-kb mercury-resistance plasmid. Prominent features are the very large number of genes (57) encoding polyketide synthases (PKSs) and nonribosomal peptide synthases (NRPSs) and the most extensive repertoire yet reported of the mycobacteria-restricted PE and PPE proteins, and related-ESX secretion systems. Some of the NRPS genes comprise a novel family and seem to have been acquired horizontally. M. marinum is used widely as a model organism to study M. tuberculosis pathogenesis, and genome comparisons confirmed the close genetic relationship between these two species, as they share 3000 orthologs with an average amino acid identity of 85%. Comparisons with the more distantly related Mycobacterium avium subspecies paratuberculosis and Mycobacterium smegmatis reveal how an ancestral generalist mycobacterium evolved into M. tuberculosis and M. marinum. M. tuberculosis has undergone genome downsizing and extensive lateral gene transfer to become a specialized pathogen of humans and other primates without retaining an environmental niche. M. marinum has maintained a large genome so as to retain the capacity for environmental survival while becoming a broad host range pathogen that produces disease strikingly similar to M. tuberculosis. The work described herein provides a foundation for using M. marinum to better understand the determinants of pathogenesis of tuberculosis.
The effect of pre‐operative anxiety on induction of anaesthesia with propofol*
Authors: Morley A. P. , Papageorgiou C. H. , Marinaki A. M. , Cooper D. J. , Lewis C. M.
Published: April 2008

In this prospective study, we investigated the effects of anxiety on the induction dose of propofol and subsequent cardiovascular changes in 197 patients. Pre‐operative state and trait anxiety scores were measured using the State Trait Anxiety Inventory. Propofol was administered at 40 mg.kg−1.h−1. Propofol dose was recorded at loss of verbal response and when EEG Bispectral Index decreased to 50. Thereafter, propofol infusion rate was reduced to 8 mg.kg−1.h−1. Cardiovascular data were collected for 15 min after starting induction. Maximum percentage decreases in heart rate and mean arterial pressure, and the point at which the latter occurred, were recorded. On multivariate analysis, anxiety scores did not significantly affect propofol dose or cardiovascular end‐points, although Bispectral Index at loss of verbal response decreased with increasing trait anxiety (p = 0.02). Anxiety, measured using State Trait Anxiety Inventory, does not appear independently to affect the induction characteristics of propofol.
Malignant hyperthermia presenting during laparoscopic adrenalectomy
Authors: O'Neill S. S. , Smurthwaite G. J.
Published: April 2008

A 44‐year‐old man presented for elective laparoscopic adrenalectomy. During the procedure his end‐tidal carbon dioxide readings rose steadily. We assumed that this was due to a prolonged carbon dioxide pneumoperitoneum until he developed ST segment depression on his electrocardiogram and a rapid rise in temperature. A diagnosis of malignant hyperthermia was made in view of the rising temperature and carbon dioxide. He responded to cooling and intravenous dantrolene. He was later confirmed to be malignant hyperthermia‐susceptible on in vitro contracture testing of a muscle biopsy. The diagnosis was delayed as the early signs of malignant hyperthermia are the same as the expected physiological changes in laparoscopic surgery. As laparoscopic surgery continues to expand we advocate vigilance to ensure early identification of this rare but potentially devastating condition.
The relationship between arterial Po2 and mixed venous Po2 in response to changes in positive end‐expiratory pressure in ventilated patients
Authors: Groeneveld A. B. J. , Schneider A. J.
Published: April 2008

The response of arterial Po2 (Pao2) to airway pressure has been used as a measure of recruitment in mechanically ventilated patients. We hypothesised that mixed venous Po2 (Pmvo2) directly affects Pao2. Sixteen patients with acute lung injury (ALI, lung injury score ≥ 1) on volume‐controlled mechanical ventilation (FIo2 0.40) were studied. Positive end‐expiratory pressure (PEEP) was increased and decreased. Incremental PEEP increased median values of Pao2, diminished venous admixture (Qva/Qt) and cardiac index, but maintained arterial Pco2 and tissue O2 uptake. These changes were reversed during decremental PEEP. However Pao2 did not increase in 37% of PEEP steps and changes in Pao2 correlated to those in Pmvo2 (rs = 0.45, p < 0.001). Changes in Pmvo2 contributed to changes in Qva/Qt in determining changes in Pao2 (p < 0.05). Pmvo2 may be an independent determinant of Pao2 during mechanical ventilation for ALI, so that dosing PEEP to recruit the lung should not be guided by arterial blood oxygenation alone. Arterial hypoxaemia with increasing PEEP may improve by reducing PEEP (or increasing tissue O2 delivery), when the fall in Pmvo2 is greater than about 0.133 kPa.
The use of N‐Terminal pro‐B Type Natriuretic Peptide in a pre‐operative setting to predict left ventricular systolic dysfunction on echocardiogram*
Authors: Messer P. B. , Singh R. , McAuley F. T. , Handley G. , Peaston B. , Snowden C. P.
Published: April 2008

Heart failure is a major risk factor for adverse postoperative events following non‐cardiac surgery. The use of transthoracic echocardiogram as a pre‐operative investigation to assess cardiac dysfunction has limitations in this setting. The N‐Terminal fragment of B‐Type natriuretic peptide (NT proBNP) has been used in screening for heart failure. We have investigated the use of NT proBNP as a screening tool for left ventricular systolic dysfunction to reduce the requirement for pre‐operative echocardiograms. Ninety‐eight pre‐operative non‐cardiac surgical patients scheduled to undergo echocardiography were assessed clinically and with an NT proBNP measurement. Echocardiogram was used to define two groups of patients depending on the presence or absence of abnormal left ventricular function and the NT proBNP level was compared between the groups using non‐parametric and receiver‐operator‐characteristic (ROC) curve analysis. In terms of pre‐operative screening, a NT proBNP of <38.2 pmol.l−1 had a 100% negative predictive value in predicting patients with normal left ventricular systolic function and would have prevented the requirement for echocardiogram in 43% of pre‐operative patients. NT proBNP was superior to electrocardiological and clinical criteria for detection of a normal echocardiogram. This may have significant impact in the pre‐operative assessment of patients undergoing non‐cardiac surgery.
The effect of lidocaine on remifentanil‐induced cough
Authors: Kim J. Y. , Park K. S. , Kim J. S. , Park S. Y. , Kim J. W.
Published: April 2008

This study was performed to investigate the incidence of remifentanil‐induced cough and evaluate the efficacy of lidocaine on its prevention. Five‐hundred patients, aged 18–70 years, were randomly allocated into two groups to receive either lidocaine 0.5 mg.kg−1 or 0.9% normal saline intravenously 1 min before remifentanil administration at a target effect‐site concentration of 4 ng.ml−1. Any episode of cough was classified as coughing and graded as mild (1–2), moderate (3–4) or severe (5 or more). We found that the overall incidence of cough was significantly higher in the saline group (69 patients; 27.6%) than that in the lidocaine group (38 patients; 15.2%) (p < 0.001). The results of logistic regression indicated that age and smoking were associated with remifentanil‐induced cough. This study demonstrated that intravenously administered lidocaine 0.5 mg.kg−1 effectively suppresses remifentanil‐induced cough without possible systemic lidocaine toxicity.
The ability of atropine to prevent and reverse the negative chronotropic effect of fingolimod in healthy subjects
Authors: Kovarik John M. , Slade Alan , Riviere Gilles‐Jacques , Neddermann Daniel , Maton Steve , Hunt Thomas L. , Schmouder Robert L.
Published: April 2008

WHAT IS KNOWN ABOUT THIS SUBJECT

• Clinical pharmacology and clinical therapeutic studies of fingolimod demonstrate that heart rate after the initial dose decreases by about 10–20% while normal circadian rhythm is preserved. With continued daily dosing, heart rate returns to normal over the next 2 weeks.

• This negative chronotropic effect is consistent with the binding of fingolimod‐phosphate to the sphingosine‐1‐phosphate receptor on atrial myocytes.

WHAT THIS STUDY ADDS

• The present clinical pharmacology study demonstrates that atropine administered at usual therapeutic doses can prevent the decrease in heart rate when given concomitantly with fingolimod and can counteract the decrease in heart rate when give at the time of the typical heart rate nadir, 4 h after the fingolimod dose.

• Although therapeutic intervention is rarely needed for reduced heart rate in patients receiving fingolimod, atropine is an option, should this be desired.

AIMS

The authors determined whether intravenous atropine can prevent or counteract the negative chronotropic effect of the immunomodulator fingolimod.

METHODS

In this randomized, placebo‐controlled, two‐period, crossover study, 12 healthy subjects received 5 mg fingolimod orally concurrently with intravenous atropine (titrated to a heart rate of 110–120 beats min−1) or intravenous placebo. A second group of 12 subjects received atropine/placebo 4 h after the fingolimod dose. Continuous telemetry measurements were made for 24 h after each fingolimod dose.

RESULTS

Fingolimod administration alone yielded a heart rate nadir of 51 ± 5 beats min−1 at a median 4 h postdose with heart rate remaining depressed at 51–64 beats min−1 over the rest of the day. Concurrent administration of fingolimod and atropine yielded a nadir of 66 ± 6 beats min−1 resulting in an atropine : placebo ratio (90% confidence interval) of 1.30 (1.22, 1.36). When atropine was administered at the time of the nadir, it was able to reverse the negative chronotropic effect of fingolimod from a heart rate of 56 ± 9 beats min−1 (placebo) to 64 ± 8 beats min−1 (atropine) resulting in an atropine : placebo ratio of 1.15 (1.04, 1.26). Atropine had no influence on the pharmacokinetics of fingolimod.

CONCLUSIONS

Atropine administered concurrently with fingolimod prevented the heart rate nadir that typically occurs 4 h postdose. Atropine administered at the time of the heart rate nadir was able to reverse the negative chronotropic effect of fingolimod.
Does a physician's specialty influence the recording of medication history in patients' case notes?
Authors: Yusuff Kazeem B. , Tayo Fola
Published: April 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Physicians undertake the documentation of medication history during clerking; where all the necessary information that guides the diagnostic and patient management tasks are obtained.

• Medication histories documented by physicians are often incomplete and generally sketchy; however, the impact of a physician's specialty on the frequency and depth of medication history they document has not been studied.

WHAT THIS STUDY ADDS

• The depth and frequency of medication history documented by physicians is significantly influenced by their specialties.

• Physicians appear more interested in documenting more frequently and in greater depth medication history information that appears to aid diagnostic tasks in their specific specialty.

AIMS

To determine the impact of a physician's specialty on the frequency and depth of medication history documented in patient medical records.

METHODS

A cross‐sectional assessment of the frequency and depth of medication history information documented by 123 physicians for 900 randomly selected patients stratified across Cardiology, Chest, Dermatology, Endocrine, Gastroenterology, Haematology, Neurology, Psychiatry and Renal specialties was carried out at a 900‐bed teaching hospital located in Ibadan, Nigeria.

RESULTS

Four hundred and forty‐three (49.2%) of the cohort were males and 457 (50.8%) were females; with mean ages 43.2 ± 18.6 and 43.1 ± 17.9 years respectively. Physicians' specialties significantly influenced the depth of documentation of the medication history information across the nine specialties (P < 0.0001). Post hoc pair‐wise comparisons with Tukey's HSD test showed that the mean scores for adverse drug reactions and adherence to medicines was highest in the Cardiology specialty; while the Chest specialty had the highest mean scores for allergy to drugs, food, chemicals and cigarette smoking. Mean scores for the use of alcohol; illicit drugs; dietary restrictions was highest for Gastroenterology, Psychiatry and Endocrine specialties respectively. Physicians' specialties also significantly influenced the frequency of documentation of the medication history across the nine specialties (P < 0.0001).

CONCLUSIONS

Physicians appear to document more frequently and in greater depth medication history information that may aid the diagnostic tasks in their specific specialty. Researchers and other users of medication history data documented in patients' medical records by physicians may want to take special cognizance of this phenomenon.
Genetic developments in autoimmune thyroid disease: an evolutionary process
Authors: Zeitlin Abigail A. , Simmonds Matthew J. , Gough Stephen C. L.
Published: April 2008

The identification of genes placing individuals at an increased risk for the development of autoimmune thyroid disease (AITD) has been a slow process. However, over the last 20 years or so real progress has been made with the mapping of novel loci, via a number of different approaches. First, through the use of traditional immunological methods, Human Leucocyte Antigen (HLA)/Major Histocompatibility Complex (MHC) was the first gene region to be associated with AITD and consistent replications have been reported. Second, the CTLA‐4 gene region on 2q33 was the first non‐MHC replicated locus to be primarily identified using the candidate gene method. Third, family‐based linkage studies led to the mapping of a new type 1 diabetes locus, the PTPN22 gene, which has subsequently been independently replicated as a susceptibility gene for Graves’ disease (GD). Fourth, despite many unsuccessful attempts at implicating the TSHR gene as a susceptibility locus for GD, a recent approach of ‘tagging’ all the common variation within the gene has led to its identification as the first GD specific locus. Moreover, the use of tag single nucleotide polymorphisms (SNPs) has also been used to implicate the recently identified type 1 diabetes locus, CD25 as a susceptibility gene for GD. Finally, large scale, ongoing genome‐wide association studies in multiple autoimmune diseases (AID) states, including AITD seem likely to lead to the identification of additional MHC and non‐MHC susceptibility loci.
The effect of growth hormone treatment on bone mineral density in prepubertal girls with Turner syndrome: a multicentre prospective clinical trial
Authors: Aycan Zehra , Cetinkaya Ergun , Darendeliler Feyza , Vidinlisan Sadi , Bas Firdevs , Bideci Aysun , Demirel Fatma , Darcan Sukran , Buyukgebiz Atilla , Yildiz Metin , Berberoglu Merih , Bundak Ruveyde
Published: April 2008

Background  Patients with Turner syndrome (TS) are treated with GH to increase adult height. Although it is well established that GH promotes longitudinal bone growth, the effects of GH treatment on bone density are less clear.

Objective  To determine how GH treatment affects trabecular bone mineral density (BMD) in girls with TS at prepubertal ages in a prospective multicentre study.

Patients and method  Twenty‐two patients with TS in the prepubertal period with a mean age of 9·8 ± 2·5 (range 3·6–12·8) years were included in the study. All girls with TS underwent measurement of areal BMD using dual‐energy X‐ray absorptiometry (DXA) to obtain pretreatment anteroposterior (AP) lumbar spine values at L1–L4. Patients received GH (Genotropin) subcutaneously for 1 year at a dose of 0·05 mg/kg/day. Height and weight were measured at 3‐monthly intervals. The AP lumbar spine areal BMD was remeasured using the same technique after 1 year of treatment. Lumbar spine BMD Z‐scores and volumetric BMD (vBMD) Z‐scores were calculated using national standards.

Results  The height SDS of our cases showed a significant increase with GH therapy. The pretreatment lumbar spine (L1–L4) BMD Z‐score was –1·2 ± 1·2 SD and the vBMD Z‐score was –0·8 ± 1·6 SD. There were no significant changes in these values after 1 year of GH treatment. Prepubertal TS girls more than 11 years of age had lower vBMD Z‐scores (–1·7 ± 1·7 SD) than the girls aged less than 11 (–0·1 ± 1·0 SD) (P < 0·05) at the onset of therapy. No significant changes were observed in these values after 1 year of GH therapy.

Conclusions  Osteopaenia becomes apparent in prepubertal TS patients as they reach pubertal age. BMD evaluation may be necessary in these prepubertal TS girls at diagnosis. Short‐term GH therapy in these TS patients does not have a significant effect on bone density when measured at a site with a predominance of trabecular bone.
Components of the metabolic syndrome predictive of its development: a 6‐year longitudinal study in Hong Kong Chinese
Authors: Cheung Bernard M. Y. , Wat Nelson M. S. , Tam Sidney , Thomas G. Neil , Leung Gabriel M. , Cheng Chun Ho , Woo Jean , Janus Edward D. , Lau Chu Pak , Lam Tai Hing , Lam Karen S. L.
Published: April 2008

Objective  To investigate which of the components of the metabolic syndrome best predict its development.

Design  Long‐term cohort of randomly selected adults.

Patients  One thousand five hundred and forty‐eight subjects from the Hong Kong Cardiovascular Risk Factor Prevalence Study who did not have the metabolic syndrome by the US National Cholesterol Education Program (NCEP) or International Diabetes Federation (IDF) criteria at baseline.

Measurements  Waist circumference, blood pressure, glucose, triglycerides and high‐density lipoprotein‐cholesterol (HDL).

Results  After a median interval of 6·4 years, there were 219 and 143 new cases (21·9 and 14·3 per 1000 person‐years) of the metabolic syndrome by the NCEP and IDF criteria, respectively. The odds ratio for the NCEP metabolic syndrome was highest for low HDL, 4·08 [95% confidence interval (CI): 2·90–5·73] and that for the IDF metabolic syndrome was highest for central obesity, 5·94 [95% CI: 3·98–8·87]. Low HDL, found in 27·8% men and 34·3% women, had the highest sensitivity for the NCEP metabolic syndrome (48% in men and 57% in women) and the IDF metabolic syndrome (41% in men and 54% in women). Central obesity had the highest positive predictive values except that triglycerides had the highest positive predictive value for the NCEP metabolic syndrome in women. The areas under the receiver operator characteristic curve for waist circumference, triglycerides and HDL were similar. A model that included waist circumference and HDL predicted the metabolic syndrome as well as a model that included all five metabolic syndrome components.

Conclusion  Obese Chinese adults should be periodically screened for the metabolic syndrome and have waist and HDL measurement.