bluuebunny/crossref_metadata_2025 huggingface dataset:
Loop Current warming by Hurricane Wilma
Authors: Oey L.‐Y. , Ezer T. , Wang D.‐P. , Fan S.‐J. , Yin X.‐Q.
Published: May 2006

Hurricanes mix and cool the upper ocean, as shown here in observations and modeling of the Caribbean Sea and the Gulf of Mexico during the passage of hurricane Wilma. Curiously, the upper ocean around the Loop Current warmed prior to Wilma's entrance into the Gulf. The major cause was increased volume and heat transports through the Yucatan Channel produced by storm‐induced convergences in the northwestern Caribbean Sea. Such oceanic variability may have important impacts on hurricane predictions.
Measurements beneath an Antarctic ice shelf using an autonomous underwater vehicle
Authors: Nicholls K. W. , Abrahamsen E. P. , Buck J. J. H. , Dodd P. A. , Goldblatt C. , Griffiths G. , Heywood K. J. , Hughes N. E. , Kaletzky A. , Lane‐Serff G. F. , McPhail S. D. , Millard N. W. , Oliver K. I. C. , Perrett J. , Price M. R. , Pudsey C. J. , Saw K. , Stansfield K. , Stott M. J. , Wadhams P. , Webb A. T. , Wilkinson J. P.
Published: May 2006

The cavities beneath Antarctic ice shelves are among the least studied regions of the World Ocean, yet they are sites of globally important water mass transformations. Here we report results from a mission beneath Fimbul Ice Shelf of an autonomous underwater vehicle. The data reveal a spatially complex oceanographic environment, an ice base with widely varying roughness, and a cavity periodically exposed to water with a temperature significantly above the surface freezing point. The results of this, the briefest of glimpses of conditions in this extraordinary environment, are already reforming our view of the topographic and oceanographic conditions beneath ice shelves, holding out great promises for future missions from similar platforms.
Bernstein mode coupling to cyclotron harmonic radiation in a plasma
Authors: Kumar Asheel , Tripathi V. K.
Published: May 2006

An electron Bernstein wave in the presence of an ion-acoustic wave of suitable wave number converts itself into cyclotron harmonic electromagnetic radiation in a plasma. The Bernstein wave imparts oscillatory velocity to electrons that couples with the density perturbation associated with the sound wave to produce a nonlinear current, driving the electromagnetic wave at sum (or difference) frequency. Conversely a large amplitude electromagnetic wave at a cyclotron harmonic can parametrically excite an electron Bernstein wave that may effectively heat the electrons.
Simulation of the nonlinear evolution of large scale relativistic electron flow in dense plasmas
Authors: Matsumoto Toshikazu , Taguchi Toshihiro , Mima Kunioki
Published: May 2006

A relativistic electron beam of about 100MA is transported through overdense plasmas in the fast ignition. The nonlinear dynamics of the relativistic electron beam in dense plasmas has been investigated using a two-dimensional fluid-particle hybrid (FPH) code [T. Taguchi et al., Phys. Rev. Lett. 86, 5055 (2001)] that combines a particle-in cell code with an Rational Cubic Interpolated Pseudo-Particle fluid code [F. Xiao et al., Comput. Phys. Commun. 93, 1 (1996)]. These simulations show that the relativistic electron beam breaks up into filaments from the Weibel instability and the filaments merge successively to larger filaments. When the relativistic electron beam diameter is large and the total current is over 100 times Alfvén limit current, many large scale filaments remain after the merging process and are confined in the initial beam diameter. It is found that the number of relativistic electron filaments decreases in proportion to t−0.9 in the fixed ion case and t−0.2 in the mobile ion case until ωpe0τ≈1000, respectively. This asymptotic behavior is caused by the random motion of filaments driven by fluctuating magnetic fields.
Four motional invariants in axisymmetric tori equilibria
Authors: Ågren O. , Moiseenko V. E.
Published: May 2006

In addition to the standard set (ε,μ,pφ) of three invariants in axisymmetric tori, there exists a fourth independent radial drift invariant Ir. For confined particles, the net radial drift has to be zero, whereby the drift orbit average Ir=⟨r¯0⟩ of the gyro center radial Clebsch coordinate is constant. To lowest order in the banana width, the radial invariant is the gyro center radial coordinate r¯0(x,v), and to this order the gyro center moves on a magnetic flux surface. The gyro center orbit projected on the (r,z) plane determines the radial invariant and first order banana width corrections to Ir are calculated. The radial drift invariant exists for trapped as well as passing particles. The new invariant is applied to construct Vlasov equilibria, where the magnetic field satisfies a generalized Grad-Shafranov equation with a poloidal plasma current and a bridge to ideal magnetohydrodynamic equilibria is found. For equilibria with sufficiently small banana widths and radial drift excursions, the approximation Ir≈r¯0(x,v) can be used for the equilibrium state.
Two-dimensional axisymmetric magnetohydrodynamic analysis of blow-by in a coaxial plasma accelerator
Authors: Cassibry J. T. , Thio Y. C. F. , Wu S. T.
Published: May 2006

When the driving magnetic pressure profile is unbalanced by the plasma density profile in a coaxial plasma accelerator, a portion of the plasma and associated current sheet may “blow by” the remaining bulk of the plasma. The fast moving plasma creates a significant back electromotive force, draining energy otherwise available for acceleration. The onset of blow-by for an unmagnetized plasma of finite length in a straight coaxial plasma accelerator was studied by exploring systematically the effects of the initial density profile, driving current, plasma temperature, inductance gradient, and electrode radii scale size on the blow-by time. In order to avoid the onset of blow-by, the principal acceleration phase needs to be less than the characteristic blow-by time, which is a function of electrode geometry, plasma conditions, and circuit parameters. For an initially uniform density profile, the total impulse at blow-by time is proportional to the current, plasma mass, jet length, and reciprocal of the electrode radius ratio.
Bounded dust-acoustic waves in a cylindrically bounded collisional dusty plasma with dust charge variation
Authors: Wei Nan-Xia , Xue Ju-Kui
Published: May 2006

Taking into account the boundary, particle collisions, and dust charging effects, dust-acoustic waves in a uniform cylindrically bounded dusty plasma is investigated analytically, and the dispersion relation for the dust-acoustic wave is obtained. The effects of boundary, dust charge variation, particle collision, and dust size on the dust-acoustic wave are discussed in detail. Due to the bounded cylindrical boundary effects, the radial wave number is discrete, i.e., the spectrum is discrete. It is shown that the discrete spectrum, the adiabatic dust charge variation, dust grain size, and the particle collision have significant effects on the dust-acoustic wave.
H-theorem for a relativistic plasma around black holes
Authors: Nicolini P. , Tessarotto M.
Published: May 2006

A statistical description of matter, formed by a relativistic plasma infalling into a black hole, is formulated, adopting a covariant kinetic approach in terms of classical point particles. By assuming that the charged particles are described by the collisionless Vlasov equation and the event horizon can be treated as a classical porous wall, the theory permits us to evaluate the entropy production rate of classical matter in the presence of an event horizon. As a result, an H-theorem is established for the classical (Shannon) kinetic entropy of the infalling matter, which holds for arbitrary models of black holes and is valid also in the presence of contracting (or expanding) event horizons.
Deep level transient spectroscopy study of nickel-germanide Schottky barriers on n-type germanium
Authors: Simoen E. , Opsomer K. , Claeys C. , Maex K. , Detavernier C. , Van Meirhaeghe R. L. , Forment S. , Clauws P.
Published: May 2006

Nickel-germanide Schottky barriers have been made on n-type germanium and evaluated by deep level transient spectroscopy in order to detect possible metal indiffusion during the 30s rapid thermal annealing (RTA) employed for the germanidation. It is shown that while no electron traps have been found for the 300 and 350°C RTA step, the double acceptor level at EC−0.3eV of substitutional nickel was observed for the 400 and 450°C samples. The corresponding concentration profile increases exponentially towards the surface from which an effective diffusion coefficient of ∼5×10−10cm2∕s at 450°C has been derived.
Direct epitaxial growth of semiconducting β-FeSi2 thin films on Si(111) by facing targets direct-current sputtering
Authors: Yoshitake T. , Inokuchi Y. , Yuri A. , Nagayama K.
Published: May 2006

Semiconducting β-FeSi2 thin films were epitaxially as-grown on Si(111) substrates at a substrate temperature of 600°C, which is at least 200°C lower than ordinary annealing temperatures, by using the facing targets direct-current sputtering (FTDCS) method using an FeSi2 target without annealing. The deposited film exhibits a smooth surface with a surface roughness root mean square of 1.47nm. The direct and indirect optical band gaps estimated from the experiment were in agreement with those of the single crystalline bulk. Temperature dependence of the electrical conductivity implied Co incorporation from the FeSi2 targets with a purity of 3N. The FTDCS method, in which a substrate is free of plasma and energetic neutral atoms diffused into the substrate owing to low Ar pressure sputtering, is effective for the direct epitaxial growth of β-FeSi2 thin films with smooth surfaces.
Infrared absorption in a quantum wire: A technique to measure different types of spin-orbit interaction strengths
Authors: Bandyopadhyay S. , Sarkar S.
Published: May 2006

We show that the dominant absorption peak due to intersubband transition in a gated quantum wire will split into a main peak and two satellite peaks if both Rashba and Dresselhaus spin-orbit interactions are present. One satellite peak will be redshifted, and the other blueshifted. From the relative intensity of either satellite peak, and the magnitude of the red- or blueshift, we can determine both Rashba and Dresselhaus interaction strengths separately, if we also carry out a Hall measurement to determine the carrier concentration and a quantized conductance step measurement to determine the energy separation between subbands. This method may be a convenient alternative to usual magnetotransport measurements used to measure spin-orbit interaction strengths. It is also more powerful because it allows us to measure the strengths of the two types of interactions separately.
Topological characteristics of InAs quantum dot with GaInAs cover using Sb surfactant
Authors: Matsuura Tetsuya , Miyamoto Tomoyuki , Koyama Fumio
Published: May 2006

Sb-introduced effects of the cover layer on topological properties were investigated by atomic force microscopy for InAs quantum dots on GaAs using molecular beam epitaxy. Size enlargement for an Sb-introduced GaInAs cover layer was found. Elongation of the photoluminescence peak wavelength with a narrow linewidth was confirmed as a result of the increase of the dot height with less size fluctuation.
Magnetic tunnel junctions with compensated magnetic moment by directly exchange-coupled NiFe∕CoGd∕NiFe trilayers
Authors: Niemeyer A. , Reiss G. , Brückl H.
Published: May 2006

The compensation of magnetic moments plays a major role in magnetic tunnel junction electrodes and is usually established by artificial trilayer ferrimagnets such as CoFe∕Ru∕CoFe. An alternative route is described here: trilayers consisting of ferromagnetic rare earth and transition metals show an antiparallel exchange coupling of the individual layers. In magnetic tunnel junctions consisting of IrMn exchange biased NiFe∕CoGd∕NiFe trilayers the total magnetic moment can thus be compensated by an appropriate choice of the individual layer thicknesses. Consequently, an enhancement of the exchange bias field and a strong reduction of the Neél coupling can be found in parallel. The compensation point can be shifted on the temperature scale by the CoGd composition, even to values above room temperature.
Magnetic ordering in Gd monopnictides: Indirect exchange versus superexchange interaction
Authors: Duan Chun-Gang , Sabiryanov R. F. , Mei W. N. , Dowben P. A. , Jaswal S. S. , Tsymbal E. Y.
Published: May 2006

The exchange interaction parameters of Gd monopnictides are deduced from fitting the total energies of different magnetic configurations to those computed within the Heisenberg model. The magnetic structures predicted by first-principles calculations as well as the Curie (Néel) temperatures obtained from Monte Carlo simulations are both in good agreement with experiments. A detailed analysis of the exchange parameters suggests that the Ruderman-Kittel-Kasuya-Yosida-type indirect exchange interactions and antiferromagnetic superexchange interactions coexist in these compounds. The magnetic order changes from ferromagnetic in GdN to antiferromagnetic in other Gd pnictides as a result of the increased ionic radius of a pnictide in the latter.
Evidence for a “dark exciton” state of PbS nanocrystals in a silicate glass
Authors: Espiau de Lamaëstre R. , Bernas H. , Pacifici D. , Franzó G. , Priolo F.
Published: May 2006

PbS nanocrystals (diameter of 5–7nm) were synthesized via sulfur ion implantation in Pb-based glasses and postannealing. They display strong emission at around 1.5μm due to quantum confinement, and a very large photoluminescence (PL) excitation cross section. The PL intensity and decay rate temperature dependences provide evidence for a large energy splitting (ca. 30meV) of the emitting exciton ground state fine structure, presumably due to the complex PbS electronic band structure.
Complex and incommensurate ordering in Al0.72Ga0.28N thin films grown by plasma-assisted molecular beam epitaxy
Authors: Wang Yiyi , Özcan Ahmet S. , Ludwig Karl F. , Bhattacharyya Anirban , Moustakas T. D. , Zhou Lin , Smith David J.
Published: May 2006

Structures with incommensurate ordering along the [0001] direction are observed in wurtzite Al0.72Ga0.28N alloys grown by plasma-assisted molecular beam epitaxy on c-plane sapphire. Films grown in environments with group-III/N ratios greater than 1 exhibit ordered superlattice structures that are incommensurate with the wurtzite crystal lattice. In contrast, films grown under nitrogen-rich conditions exhibit ordered structures with a periodicity of four cation-N monolayers. The increasing complexity of the ordering with increasing Ga-rich growth environment suggests that the ordering is related to the presence of a Ga overlayer believed to exist on the surface of the growing film.
Recent Advances in Supramolecular Design and Assembly of Silver(I) Coordination Polymers
Authors: Chen Chun-Long , Kang Bei-Sheng , Su Cheng-Yong
Published: May 2006

The supramolecular chemistry of Ag(i) coordination assemblies continues to attract attention due to their versatile structural diversity and potential physical and chemical functions. This article provides a short review of recent advances in the design and construction of Ag(i) coordination polymers with special emphasis on the Ag(i) ion coordination geometry, ligand functionality, and supramolecular interactions. The potential functions of Ag(i) coordination polymers are briefly summarized.
Time-Resolved Micro Liquid Desorption Mass Spectrometry: Mechanism, Features, and Kinetic Applications
Authors: Charvat Ales , Bógehold Andreas , Abel Bernd
Published: May 2006

Liquid water beam desorption mass spectrometry is an intriguing technique to isolate charged molecular aggregates directly from the liquid phase and to analyze them employing sensitive mass spectrometry. The liquid phase in this approach consists of a 10 µm diameter free liquid filament in vacuum which is irradiated by a focussed infrared laser pulse resonant with the OH-stretch vibration of bulk water. Depending upon the laser wavelength, charged (e.g. protonated) macromolecules are isolated from solution through a still poorly characterized mechanism. After the gentle liquid-to-vacuum transfer the low-charge-state aggregates are analyzed using time-of-flight mass spectrometry. A recent variant of the technique uses high performance liquid chromatography valves for local liquid injections of samples in the liquid carrier beam, which enables very low sample consumption and high speed sample analysis. In this review we summarize recent work to characterize the ‘desorption’ or ion isolation mechanism in this type of experiment. A decisive and interesting feature of micro liquid beam desorption mass spectrometry is that — under certain conditions — the gas-phase mass signal for a large number of small as well as supramolecular systems displays a surprisingly linear response on the solution concentration over many orders of magnitude, even for mixtures and complex body fluids. This feature and the all-liquid state nature of the technique makes this technique a solution-type spectroscopy that enables real kinetic studies involving (bio)polymers in solution without the need for internal standards. Two applications of the technique monitoring enzyme digestion of proteins and protein aggregation of an amyloid model system are highlighted, both displaying its potential for monitoring biokinetics in solution.
Hydroamidation of Alkenes with N-Substituted Formamides
Authors: Nath Dilip Chandra Deb , Fellows Christopher M. , Kobayashi Toshiaki , Hayashi Teruyuki
Published: May 2006

Hydroamidation of olefins with N-substituted formamides is performed with dodecacarbonyltriruthenium (Ru3(CO)12) at 180°C under N2 or CO atmosphere in toluene and in a series of ionic liquids. Yields of 99% with 94–97% exo selectivity are found in the addition of N-methylformamide to 2-norbornene under CO both in toluene and in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [bmim][NTf2]. The presence of CO or a phosphine is necessary for significant reaction to occur, with CO more effective than triphenylphosphine in all ionic liquids investigated. Reasonable yields are achieved at low pressures, in contrast to most reported hydroamidations. Conversion, exo-selectivity, and selectivity fall with increasing steric bulk of the N-formamide substituent, and disubstituted formamides are inactive. Of the terminal alkenes investigated, only styrene can be hydroamidated.
Copper Partitioning Among Mineral and Organic Fractions in Biosolids
Authors: Oliver I. W. , Merrington G. , McLaughlin M. J.
Published: May 2006

Environmental Context.Only a portion of the total amount of heavy metals present in sewage biosolids is accessible to organisms, including plants, and therefore only that portion presents any possible toxicity threat. However, metals such as copper, which are commonly associated to a large degree with the organic fraction, may become more accessible over time as organic components degrade. Determining the extent of partitioning of Cu between the organic and inorganic fractions may provide an indication of any long-term risks associated with utilisation of biosolids in agriculture. Abstract.Metal partitioning between organic and mineral fractions in biosolids may provide an indication of the long-term risks associated with land application of the material. For example, metals found to partition into the organic phase may pose a potential threat when the organic matter is decomposed, whereas metals bound in the mineral fraction would be expected to remain stable over time (given no changes in other environmental conditions) owing to the stability of mineral components. Therefore the question of which components bind copper in biosolids, and whether the sorption capacity is maintained over time, was addressed in the present study. Biosolids incubated for 21 months and non-incubated controls were examined. The solid–solution distribution coefficient (Kd) for Cu was measured in whole biosolids and in biosolid organic and mineral fractions via batch experiments employing the radioactive isotope 64Cu. The mineral fraction was isolated by NaOCl oxidation, whereas the organic fraction was isolated using HF. Results found the relative importance of mineral and organic fractions to Cu sorption varies between biosolids, and in some cases can vary over time. Reduction in sorption capacity caused by losses of organic matter in some biosolids suggests the possibility of increased availability of biosolid metals over time.
Large, regulated forest floodplain is an ideal recruitment zone for non-native common carp (Cyprinus carpio L.)
Authors: Stuart Ivor G. , Jones Matthew
Published: May 2006

Non-native common carp (Cyprinus carpio L.) are the most abundant large-bodied fish in the Murray–Darling Basin. The abundance of common carp larvae and young-of-the-year appears to increase after flooding, although the relative contribution of floodplain habitats compared to riverine areas remains unresolved. Larval nets were used monthly from September 2000 to January 2001 to identify common carp spawning and recruitment areas in the regulated Murray River and floodplain around the Barmah–Millewa forest. Five non-native and five native fish species comprising 136 111 individuals were collected, with common carp constituting 88% of the overall catch. Less than 1% of common carp, however, originated from the Murray River upstream of the Barmah–Millewa floodplain. Consequently, this floodplain appears to be a major source of common carp recruitment in the mid-Murray area. Conversely, eggs from large-bodied native fish were only present in the Murray River and not the Barmah floodplain. There are opportunities for common carp control in this area, to potentially reduce populations in a wider river reach. Implementation of common carp control measures in the Barmah–Millewa floodplain should be further investigated, particularly with regard to seasonal irrigation flows, obligatory migration routes and in the timing of future large-scale environmental water allocations.
The evolution of Queensland spiny mountain crayfish of the genus Euastacus. II. Investigating simultaneous vicariance with intraspecific genetic data
Authors: Ponniah Mark , Hughes Jane M.
Published: May 2006

Phylogenetic evidence suggested that the Queensland Euastacus diversified through ‘simultaneous vicariance’, where the range of a widespread ancestral Euastacus receded to tops of mountains with the Pliocene warming of the continent and subsequent isolation lead to speciation. Implicit in the simultaneous vicariance hypothesis are three postulates on ancestral history: (1) warm temperatures were effective barriers to ancestral gene flow; (2) the ancestral Euastacus had an extensive contiguous distribution; and (3) there was a single vicariant event associated with Pliocene warming. It is argued that if there was interspecific diversification due to simultaneous vicariance then, within extant species, there are three predictions on current population structure. First, lowland areas, even those connected by streams, would be barriers to contemporary dispersal. Second, there would be contemporary dispersal between catchments covered by mesic rainforests. Third, there would have been recent Pleistocene intraspecific vicariant events. The population structure of E. robertsi, E. fleckeri, E. hystricosus and E. sulcatus was investigated with mtDNA and allozymes and it was found that the intraspecific data were consistent with these predictions. Furthermore, the Euastacus underwent limited range expansions during the cooler Pleistocene glacial cycles, and it is hypothesised that during cooler glacial periods, lowlands were still effective barriers to dispersal because of increased Pleistocene aridity.
Rhytismatales of Australia: the genus Marthamyces
Authors: Johnston Peter R.
Published: May 2006

Six species of Marthamyces are reported for Australia. Three of the species are described as new, the others had previously been reported from Australia as species in the genera Propolis and Naemacyclus. Most of the Australian species are host-specialised: M. emarginatus is known only from Eucalyptus, M. gilvus from Cyperaceae, M. hakeae from Hakea, and M. oritis from Orites. Marthamyces barbatus, common on Eucalyptus, is known also from a single collection on Richea. Marthamyces quadrifida, although known from only a few Australian collections, is a widespread tropical species and is likely to be common on a range of hosts in northern Australia. All species are described and illustrated, and a key to the Australian Marthamyces species is provided.
Local molecular field theory for effective attractions between like charged objects in systems with strong Coulomb interactions
Authors: Chen Yng-Gwei , Weeks John D.
Published: May 2006

Strong, short-ranged positional correlations involving counterions can induce a net attractive force between negatively charged strands of DNA and lead to the formation of ion pairs in dilute ionic solutions. However, the long range of the Coulomb interactions impedes the development of a simple local picture. We address this general problem by mapping the properties of a nonuniform system with Coulomb interactions onto those of a simpler system with short-ranged intermolecular interactions in an effective external field that accounts for the averaged effects of appropriately chosen long-ranged and slowly varying components of the Coulomb interactions. The remaining short-ranged components combine with the other molecular core interactions and strongly affect pair correlations in dense or strongly coupled systems. We show that pair correlation functions in the effective short-ranged system closely resemble those in the uniform primitive model of ionic solutions and illustrate the formation of ion pairs and clusters at low densities. The theory accurately describes detailed features of the effective attraction between two equally charged walls at strong coupling and intermediate separations of the walls. Analytical results for the minimal coupling strength needed to get any attraction and for the separation at which the attractive force is a maximum are presented.
Educational leadership: an Islamic perspective
Authors: Shah Saeeda
Published: May 2006

Ethnocentric concepts, theories and practices in education, predominantly embedded in western philosophy and values, tend to ignore the growing multicultural nature of educational institutions. This article draws attention to the knowledge gap in mainstream literature regarding diverse perspectives of educational leadership—an issue which is foreseen as gaining higher significance with the fast‐changing societal structures in Britain. Having worked as a Muslim woman educational leader/manager in higher education in an Islamic state for more than two decades, and now working at a British university, positioned as a non‐White woman Muslim, the author endorses the need to move beyond ethnocentrisms and to work towards developing complex theoretical constructs to reconceptualise educational leadership, drawing from perspectives held by diverse ethnic groups—students and communities. How learners from diverse philosophical and ethnic backgrounds conceive and perceive educational leadership, and how they receive it, is bound to interact with their learning experience and performance. This article briefly introduces leadership as a concept formulated in context. It presents philosophical and theoretical underpinnings of these conceptualisations from an Islamic perspective, and highlights the interplay between knowledge and leadership. The article deliberates how these discourses interact to formulate ‘educational leadership’ in Muslim societies, and explores the implications of these constructions with a focus on the British context, where Muslims are in a minority, pointing to the significance of understanding philosophical diversity for embracing population diversity.
Cost analysis of an open low-field (0.23t) MRI unit: effect of procedure shares in combined imaging, interventional, and neurosurgical use
Authors: Ronkainen J. , Tervonen O.
Published: May 2006

Purpose: To analyze the cost structure of procedures performed in a multipurpose interventional magnetic resonance imaging (IMRI) unit and to analyze the effect of procedure shares on cost structure.

Material and Methods: During a 1-year period, 691 procedures were performed in the IMRI unit, of which 563 were diagnostic MRI examinations, 89 MRI-guided interventions, and 39 MRI-guided neurosurgical operations. Three alternative utilization models of IMRI were created to simulate different local institutions by adjusting the proportions of different procedures. The costs of procedures were calculated by activity-based cost analysis.

Results: The cost of the main procedure (imaging, biopsy, injection, or operation) was the most significant item in all procedures, accounting for 66–89% of the total costs. The volume of imaging has a major effect on unit costs. Volume is not such a deterministic factor in interventions due to the high material costs. The volume of neurosurgical use of IMRI has a major effect on the costs of radiological procedures due to the long operation times.

Conclusion: The volumes of different procedures done on an IMRI unit have significant effects on the unit costs of the procedures.
Magnetic resonance imaging in linburg-comstock anomaly
Authors: Karalezli N. , Haykir R. , Karakose S. , Yildirim S.
Published: May 2006

Purpose: To determine the usefulness of magnetic resonance imaging (MRI) in detecting the tendinous connection in Linburg-Comstock anomaly.

Material and Methods: The study comprised 52 patients attending the orthopedic clinic for different hand problems. They were also examined for the presence of Linburg-Comstock anomaly, which was present in nine, and these patients were examined by MRI.

Results: The tendinous connection between flexor pollicis longus and flexor digitorum longus in all patients was shown by MRI. The connections were in the wrist, just proximal to the radiocarpal joint or distal forearm.

Conclusion: MRI can show localization of the connection in this anomaly and helps the surgeon perform the operation with a limited incision. The operation time is therefore shorter and wound scarring less prominent.
Hepatocellular carcinoma in association with hepatic focal nodular hyperplasia
Authors: Langrehr J. M. , Pfitzmann R. , Hermann M. , Radke C. , Neuhaus P. , Pech M. , Denecke T. , Felix R. , Hänninen E. L.
Published: May 2006

Purpose: To report the association between hepatocellular carcinoma (HCC) and hepatic focal nodular hyperplasia (FNH) and the possible impact on clinical decision-making with regard to resective approaches in patients with FNH.

Material and Methods: We retrospectively analyzed the findings in 77 adult patients who underwent liver resections for FNH between October 1989 and September 2001 at our center. HCC within the confines of FNH was found in two patients. We demonstrate the magnetic resonance imaging (MRI) and macroscopic and microscopic findings.

Results: Presurgical MRI demonstrated heterogeneous signal characteristics of moderately hyperintense FNH on T2-weighted images and, after IV administration of super-paramagnetic iron oxide particles, HCC in FNH was barely delineable. Both patients underwent successful right hemihepatectomy to remove the suspicious FNH with diameters of 12 and 14 cm; intralesional HCC diameters were 3 and 5 cm, respectively. Patients could be rapidly dismissed. However, one patient died after recurrence of HCC 1.5 years after surgery, whereas the other patient continues tumor-free 4 years after surgery. Alpha-feto-protein was normal in both patients.

Conclusion: In FNH with rapid growth tendency and heterogenic MR appearance, surgical removal should be considered to overcome the risk of inadequate therapy in the very rare group of patients with HCC in association with FNH.
Central nervous system aspergillosis: magnetic resonance imaging, diffusion-weighted imaging, and magnetic resonance spectroscopy features
Authors: Oner A. Y. , Celik H. , Akpek S. , Tokgoz N.
Published: May 2006

Aspergillus infection is invasive in nature in the immunosuppressed population and disseminates throughout the body, with the brain being a common site. Conventional magnetic resonance imaging (MRI) combined with diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) play a life-saving role in the early diagnosis and treatment monitoring of this potentially fatal infection. We present MRI, DWI, and MRS findings of a case of central nervous system aspergillosis with treatment follow-up.
Aneurysm re-rupture during computed tomography angiography
Authors: Pérez-Núñez Á. , Alén J. F. , Ramos A. , Millán J. M.
Published: May 2006

Re-rupture of cerebral aneurysms during conventional angiography, demonstrated by contrast leakage into the extravascular space, is well known and well documented. However, the occurrence of this complication during computed tomography (CT) angiographic examinations has rarely been published despite its extensive use. We present the clinical and radiological features of a rebleeding event during a CT angiographic study. No hemodynamic or contrast-related factors can be evoked predisposing to he occurrence of this complication during this imaging technique. This, along with the short study time, may explain the rarity of this coincidence.
Complete familial currarino triad in association with hirschsprung's disease: magnetic resonance imaging features and the spectrum of anorectal malformations
Authors: Kilickesmez O. , Hakki Gol I. , Uzun M. , Oruk C.
Published: May 2006

Currarino syndrome, a rare hereditary condition, is defined as a partial sacral agenesis associated with a presacral mass and anorectal malformation. The authors present two siblings with complete Currarino triad and their mother with incomplete triad. The complete Currarino triad in the older sibling was associated with Hirschsprung's disease as the second reported case in the literature. Anorectal malformations, whether suspected of Currarino syndrome or not, should be examined with lumbosacral magnetic resonance imaging.
Characterizing the Emerging Population of Prescription Opioid Abusers
Authors: Sigmon Stacey C.
Published: May 2006

Despite an alarming recent increase in prescription opioid abuse, the characteristics of prescription opioid abusers remain largely unknown. In this study, the demographic and drug use characteristics of 75 methadone patients (36 prescription opioid and 39 heroin users) were compared using a retrospective chart review. Prescription opioid abusers exhibited a profile of characteristics that may predict favorable treatment response, including less severe opioid use and IV drug use, and greater social stability compared to primary heroin abusers. Despite the limitations inherent in this retrospective chart review, this study provides initial evidence that prescription opioid abusers may have a number of characteristics that predict favorable treatment response. This new information may inform and assist current efforts to develop efficacious treatments for prescription opioid abuse.
The Psychosocial Benefits of Alcoholics Anonymous
Authors: Suire Jared G. , Bothwell Robert K.
Published: May 2006

A quasi‐experimental design was implemented to evaluate the attitudes of alcoholics toward themselves and others after they had worked all twelve steps of an AA program compared to those who had not yet completed all twelve steps. One hundred individuals who were attending AA meetings were selected so that one half had completed all of the steps and the other half had not. Participants were tested in individual sessions during which they completed a series of questionnaires. Measures were taken of global self‐esteem, social self‐esteem, social confidence, network trust, fear of negative evaluation, need for approval, preoccupation with relationships, discomfort with closeness, relationships as secondary, and optimism. A principal components analysis of participants' responses to these measures revealed that the factors being assessed could be divided into one regarding interpersonal insecurity and another regarding social potency. The data showed that alcoholics who had been able to stay in the program and work through all twelve steps had lower levels of interpersonal insecurity than those who were just beginning to work the steps. No significant differences were found in social potency between those who had completed the steps and those who had not completed the steps. Further research is needed to clarify the specific nature of changes that occur in personality as alcoholics work through the twelve steps within community‐based AA programs.
Intrinsic Capacities of Molecular Sensors of the Unfolded Protein Response to Sense Alternate Forms of Endoplasmic Reticulum Stress
Authors: DuRose Jenny B. , Tam Arvin B. , Niwa Maho
Published: May 2006

The unfolded protein response (UPR) regulates the protein-folding capacity of the endoplasmic reticulum (ER) according to cellular demand. In mammalian cells, three ER transmembrane components, IRE1, PERK, and ATF6, initiate distinct UPR signaling branches. We show that these UPR components display distinct sensitivities toward different forms of ER stress. ER stress induced by ER Ca2+ release in particular revealed fundamental differences in the properties of UPR signaling branches. Compared with the rapid response of both IRE1 and PERK to ER stress induced by thapsigargin, an ER Ca2+ ATPase inhibitor, the response of ATF6 was markedly delayed. These studies are the first side-by-side comparisons of UPR signaling branch activation and reveal intrinsic features of UPR stress sensor activation in response to alternate forms of ER stress. As such, they provide initial groundwork toward understanding how ER stress sensors can confer different responses and how optimal UPR responses are achieved in physiological settings.
Evolution of ‘pollinator’- attracting signals in fungi
Authors: Schiestl Florian P , Steinebrunner Fabrizio , Schulz Claudia , von Reuß Stephan , Francke Wittko , Weymuth Christophe , Leuchtmann Adrian
Published: May 2006

Fungi produce a plethora of secondary metabolites yet their biological significance is often little understood. Some compounds show well-known antibiotic properties, others may serve as volatile signals for the attraction of insects that act as vectors of spores or gametes. Our investigations in an outcrossing, self-incompatible fungus show that a fungus-produced volatile compound with fungitoxic activities is also responsible for the attraction of specific insects that transfer gametes. We argue that insect attraction using this compound is likely to have evolved from its primary function of defence—as has been suggested for floral scent in the angiosperms. We, thus, propose that similar yet convergent evolutionary pathways have lead to interspecific communication signals in both fungi and plants.
Intersex in the clam
Scrobicularia plana
: a sign of endocrine disruption in estuaries?
Authors: Chesman B.S , Langston W.J
Published: May 2006

The phenomenon of endocrine disruption is currently a source of growing concern. Feminization of male fish in UK rivers has been shown to occur extensively and has been linked with exposure to endocrine-disrupting compounds present in the environment. Much less is known of the extent and scale of endocrine disruption in estuarine and marine ecosystems, particularly in invertebrates.

We present evidence that intersex, in the form of ovotestis, is occurring in the common estuarine bivalve
Scrobicularia plana
, which is considered to be inherently gonochoristic. We report varying degrees in the severity of ovotestis in male
S. plana
, and have adopted and developed a grading method to assess the extent of this intersex condition.

These findings indicate that
S. plana
offers potential for widespread screening and investigation of endocrine disruption, helping to focus remediatory strategy.
Avian predators taste–reject aposematic prey on the basis of their chemical defence
Authors: Skelhorn John , Rowe Candy
Published: May 2006

Avian predators learn to avoid defended insects on the basis of their conspicuous warning coloration. In many aposematic species, the level of chemical defence varies, with some individuals being more defended than others. Sequestration and production of defence chemicals is often costly and therefore less defended individuals enjoy the benefits of the warning signal without paying the full costs of chemical production. This is a fundamental theoretical problem for the evolutionary stability of aposematism, since less defended individuals appear to be at a selective advantage. However, if predators sample aposematic prey and selectively reject individuals on the basis of their chemical investment, aposematism could become evolutionarily stable. Previous research aimed at testing whether birds can use taste to discriminate between palatable and unpalatable prey has been confounded by other experimental factors. Here, we show that birds can taste and reject prey entirely on the basis of an individual's level of chemical defence and more importantly, they can make decisions on whether or not to consume a defended individual based upon their level of chemical investment. We discuss these results in relation to the evolution of aposematism, mimicry and defence chemistry.
The use of negative penalty functions in linear systems of equations
Authors: Askes Harm , Ilanko Sinniah
Published: May 2006

Contrary to what is commonly thought, it is possible to obtain convergent results with negative (rather than positive) penalty functions. This has been shown and proven on various occasions for vibration analysis, but in this contribution it will also be shown and proven for systems of linear equations subjected to one or more constraints. As a key ingredient in the developed arguments, a pseudo-force is identified as the derivative of the constrained degree of freedom with respect to the inverse of the penalty parameter. Since this pseudo-force can be proven to be constant for large absolute values of the penalty parameter, it follows that the exact solution is bounded by the results obtained with negative and positive penalty parameters. The mathematical proofs are presented and two examples are shown to illustrate the principles.
Short- and long-term population dynamical consequences of asymmetric climate change in black grouse
Authors: Ludwig Gilbert X , Alatalo Rauno V , Helle Pekka , Lindén Harto , Lindström Jan , Siitari Heli
Published: May 2006

Temporal asymmetry in patterns of regional climate change may jeopardize the match between the proximate and ultimate cues of the timing of breeding. The consequences on short- and long-term population dynamics and trends as well as the underlying mechanisms are, however, often unknown. Using long-term data from Finland, we demonstrate that black grouse (
Tetrao tetrix
) have responded to spring warming by advancing both egg-laying and hatching. However, early summer (the time of hatching) has not advanced, and chicks have to face colder post-hatching conditions. Demonstrating that these conditions are critical to post-hatching survival, we show that chicks are increasingly suffering higher mortality because they hatch too early. Consequently, breeding success and population size has severely declined over the past four decades. Finally, we modelled the impact of this particular climate change scenario on population dynamics and show that the mismatch can further explain the observed collapse of cyclic fluctuations. Because the evolutionary response of grouse is lagging behind the novel selective pressures, seasonally asymmetric climate change is likely to constitute an important determinant of future short- and long-term changes in the dynamics of black grouse populations.
Embryo development and ageing in birds and mammals
Authors: Ricklefs Robert E
Published: May 2006

The rate of ageing is a genetically influenced feature of an individual's life history that responds to selection on lifespan. Various costs presumably constrain the evolution of prolonged life, but these have not been well characterized and their general nature is unclear. The analyses presented here demonstrate a correlation among birds and mammals between rates of embryonic growth and ageing-related mortality, which are quantified by the exponents of fitted power functions. This relationship suggests that rapid early development leads to accelerated ageing, presumably by influencing some aspect of the quality of the adult individual. Although the mechanisms linking embryo growth rate and ageing are not known, a simple model of life-history optimization shows that the benefits of longer life can be balanced by connected costs of extended development.
Fibroblast migration and collagen deposition during dermal wound healing: mathematical modelling and clinical implications
Authors: McDougall Steven , Dallon John , Sherratt Jonathan , Maini Philip
Published: May 2006

The extent to which collagen alignment occurs during dermal wound healing determines the severity of scar tissue formation. We have modelled this using a multiscale approach, in which extracellular materials, for example collagen and fibrin, are modelled as continua, while fibroblasts are considered as discrete units. Within this model framework, we have explored the effects that different parameters have on the alignment process, and we have used the model to investigate how manipulation of transforming growth factor-β levels can reduce scar tissue formation. We briefly review this body of work, then extend the modelling framework to investigate the role played by leucocyte signalling in wound repair. To this end, fibroblast migration and collagen deposition within both the wound region and healthy peripheral tissue are considered. Trajectories of individual fibroblasts are determined as they migrate towards the wound region under the combined influence of collagen/fibrin alignment and gradients in a paracrine chemoattractant produced by leucocytes. The effects of a number of different physiological and cellular parameters upon the collagen alignment and repair integrity are assessed. These parameters include fibroblast concentration, cellular speed, fibroblast sensitivity to chemoattractant concentration and chemoattractant diffusion coefficient. Our results show that chemoattractant gradients lead to increased collagen alignment at the interface between the wound and the healthy tissue. Results show that there is a trade-off between wound integrity and the degree of scarring. The former is found to be optimized under conditions of a large chemoattractant diffusion coefficient, while the latter can be minimized when repair takes place in the presence of a competitive inhibitor to chemoattractants.
Children Photographing Well‐being: Facilitating Participation in Research
Authors: Nic Gabhainn Saoirse , Sixsmith Jane
Published: May 2006

Children aged 8–12 years took 723 photographs representing well‐being. Another group of children categorised the photographs, identified what was missing and discussed their inter‐relationships. The largest categories were ‘people I love the most (friends)’ (23.2%), ‘activities’ (18%), ‘food and drink’ (17.2%) and ‘animals/pets’ (12.8%). Children reported that the categories were all related and could be subsumed into the general category ‘the way I live’, reflecting their holistic integrationist perspective on well‐being which in turn mirrors the whole child perspective of the Irish National Children's Strategy. The usefulness and limitations of this approach to working with children are discussed. Copyright © 2005 National Children's Bureau.