bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface modification of gold nanoparticles with polyhedral oligomeric silsesquioxane and incorporation within polymer matrices
Authors: Kuo Shiao‐Wei , Wu Yung‐Chien , Lu Chu‐Hua , Chang Feng‐Chih
Published: March 2009

A new approach to achieve polymer‐mediated gold ferromagnetic nanocomposites in a polyhedral oligomeric silsesquioxane (POSS)‐containing random copolymer matrix has been developed. Stable and narrow distributed gold nanoparticles modified by 3‐mercaptopropylisobutyl POSS to form Au‐POSS nanoparticles are prepared by two‐phase liquid‐liquid method. These Au‐POSS nanoparticles form partial particle aggregation by blending with poly(n‐butyl methacrylate) (PnBMA) homopolymer because of poor miscibility between Au‐POSS and PnBMA polymer matrix. The incorporation the POSS moiety into the PnBMA main chain as a random copolymer matrix displays well‐dispersed gold nanoparticles because the POSS‐POSS interaction enhances miscibility between gold nanoparticles and the PnBMA‐POSS copolymer matrix. This gold‐containing nanocomposite exhibits ferromagnetic phenomenon at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 811–819, 2009
A method for site‐specific labeling of multiple protein thiols
Authors: Kuiper Johanna M. , Pluta Radek , Huibers Wim H. C. , Fusetti Fabrizia , Geertsma Eric R. , Poolman Bert
Published: March 2009

We present a generic method for the site‐specific and differential labeling of multiple cysteine residues in one protein. Phenyl arsenic oxide has been employed as a protecting group of two closely spaced thiols, allowing first labeling of a single thiol. Subsequently, the protecting group is removed, making available a reactive dithiol site for labeling with a second probe. For proof‐of‐principle, single and triple Cys mutants of the sulphate binding protein of an ABC transporter were constructed. The closely spaced thiols were engineered on the basis of the crystal structure of the protein and placed in different types of secondary structure elements and at different spacing. We show that phenyl arsenic oxide is a good protecting group for thiols spaced 6.3–7.3 Å. Proteins were labeled with two different fluorescent labels and the labeling ratios were determined with UV‐Vis spectroscopy and MALDI‐Tof mass spectrometry. The average labeling efficiency was ∼80% for the single thiol and 65–90% for the dithiol site.
Key role of the N‐terminus of chicken annexin A5 in vesicle aggregation
Authors: Turnay Javier , Guzmán‐Aránguez Ana , Lecona Emilio , Barrasa Juan I. , Olmo Nieves , Lizarbe Ma Antonia
Published: March 2009

Annexins are calcium‐dependent phospholipid‐binding proteins involved in calcium signaling and intracellular membrane trafficking among other functions. Vesicle aggregation is a crucial event to make possible the membrane remodeling but this process is energetically unfavorable, and phospholipid membranes do not aggregate and fuse spontaneously. This issue can be circumvented by the presence of different agents such as divalent cations and/or proteins, among them some annexins. Although human annexin A5 lacks the ability to aggregate vesicles, here we demonstrate that its highly similar chicken ortholog induces aggregation of vesicles containing acidic phospholipids even at low protein and/or calcium concentration by establishment of protein dimers. Our experiments show that the ability to aggregate vesicles mainly resides in the N‐terminus as truncation of the N‐terminus of chicken annexin A5 significantly decreases this process and replacement of the N‐terminus of human annexin A5 by that of chicken switches on aggregation; in both cases, there are no changes in the overall protein structure and only minor changes in phospholipid binding. Electrostatic repulsions between negatively charged residues in the concave face of the molecule, mainly in the N‐terminus, seem to be responsible for the impairment of dimer formation in human annexin A5. Taking into account that chicken annexin A5 presents a high sequence and structural similarity with mammalian annexins absent in birds, as annexins A3 and A4, some of the physiological functions exerted by these proteins may be carried out by chicken annexin A5, even those that could require calcium‐dependent membrane aggregation.
Field experiments to assess approaches for spray drift incident investigation
Authors: Rimmer Duncan A , Johnson Paul D , Kelsey Adrian , Warren Nicholas D
Published: March 2009

BACKGROUND: Spray trials were conducted to determine the variation in primary spray drift deposition between trials under very similar conditions, in order to assess the feasibility of developing a computational tool to aid post‐event investigations of pesticide spray incidents. Pesticide deposition was examined by analysis of filter paper and vegetation samples.

RESULTS: Considerable variation in the drift profile was found. The overall estimate of the spray drift decay term was −1.13 (95% confidence interval −1.02 to −1.24), with statistically significant differences between plots. Variation in the drift profile between neighbouring essentially identical plots indicates the variation in deposition that might be expected over small distances. Vegetation samples were found to have considerably lower capture efficiency than filter papers. Importantly, degradation of pesticides was found to have little effect on the pesticide drift profile over a 14 day period.

CONCLUSIONS: The levels of spatial variation in spray drift deposits between runs and plots observed in this study suggest serious limitations to the inferences that may be drawn from limited numbers of post‐incident samples. In particular, they would limit inferences about the spray conditions that could be drawn from an estimate of the drift profile derived from limited post‐incident samples. © Crown copyright 2009. Reproduced with permission of Her Majesty's Stationery Office. Published by John W iley & Sons, Ltd.
Current management of juvenile idiopathic arthritis
Authors: Galea Paul
Published: March 2009

Our series Prescribing in children gives practical advice for successful management of childhood problems in general practice. Here, the author describes the available treatment options for juvenile idiopathic arthritis and their place in management. Copyright © 2009 Wiley Interface Ltd
Shape of indium nitride quantum dots and nanostructures grown by metal organic vapour phase epitaxy
Authors: Ploch Simon , Meissner Christian , Pristovsek Markus , Kneissl Michael
Published: March 2009

We report on the shape of indium nitride quantum dots (QDs) grown on 2 μm thick c‐plane (0001) GaN on sapphire in a horizontal MOVPE (Metal Organic Vapour Phase Epitaxy) reactor at temperatures between 550 °C and 590 °C. Ex situ X‐ray deflection (XRD) suggested pure relaxed InN. Atomic Force Microscopy (AFM) investigations show two different types of QDs, mesa shaped and cone like structures. The density of the mesa increases with decreasing temperature while the density of the cones remains constant at 2 × 108/cm2. The mean height varies between 15 nm and 40 nm for mesa and 70 nm for conic structures.

The mean diameter increases with increasing temperature from 70 nm at 550 °C to 230 nm at 590 °C for both structure types. The mesa type structures exhibit a hexagonal footprint the cone type structures often deviate slightly from this. With increasing growth temperatures the ratio of cone to mesa type structures increases. For both structures {1$ \bar 1 $02} and {$ \bar 1 $102} side facets, which seem to be the most temperature stable ones dominate. The origin for the two different structure types will be discussed. Possible causes are two different growth polarities of the InN QDs, but also nucleation on different types of defects (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of GaN nanorods grown catalyst‐free on r‐plane sapphire
Authors: Sebald K. , Kalden J. , Voss T. , Gutowski J. , Aschenbrenner T. , Kunert G. , Kruse C. , Figge S. , Hommel D.
Published: March 2009

Ensembles and single GaN nanorods grown by catalyst‐ and mask‐free molecular beam epitaxy on r‐plane sapphire are characterized by photoluminescence spectroscopy. The nanorods are well aligned and symmetrically tilted in two directions with an angle of 62° to the substrate surface. They possess an average length of 2 μm with an aspect ratio of about 1:10. The emission peaks of free and bound excitons can be identified and their temperature dependence is analysed. The high crystalline quality is indicated by the spectral width of the dominant emission peaks being comparable for the ensemble and single nanorods as well as by the absence of the stacking‐fault‐related yellow photoluminescence. The comparison of the photoluminescence spectra for an ensemble of nanorods and a single one gives insight into the heating of the nanorod under illumination when it is detached from the sample substrate (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermally induced acoustic waves in porous silicon
Authors: Gavrilchenko Iryna V. , Benilov Arthur I. , Shulimov Yuriy G. , Skryshevsky Valeriy A.
Published: March 2009

Thermally induced acoustic waves in structures with porous silicon have been studied. Two different schemas of acoustic phenomena recording are compared: in the first one a signal from microphone was measured as function of output frequency, in second one the resistance of porous silicon was measured using Wheatstone bridge. For both methods, the resonance peak is situated in same frequencies depending on difference in thermal properties between porous silicon and c‐Si as well as geometry of studied structures. 1.0 kHz shifting of resonance peak in saturated alcohol vapors comparing to ambient air is observed. It can be applied as new transducer for chemical sensors based on porous silicon. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conformal P‐N junctions in macroporous silicon for photovoltaic energy conversion
Authors: Clarkson Jeffrey P. , See Gloria G. , Veeramachaneni Bharat , Gadeken Larry L. , Hirschman Karl D. , Fauchet Philippe M.
Published: March 2009

We report on the fabrication of a macroporous silicon diode that successfully operates in a photovoltaic mode of energy conversion. Typical device structures are fabricated on 4″, Cz grown, <100>, p‐type, 5 – 30 Ω‐cm, Si substrates and make use of random or pre‐patterned macroporous silicon films up to 100 μm thick with pores ∼1 μm in diameter and a center‐to‐center pore spacing of 2.5 μm. Phosphorous dopants are introduced throughout the porous silicon region with a newly adapted technique based on proximity rapid thermal diffusion. This development effort has enhanced the uniformity of dopant diffusion into the pores and subsequently improved device performance. The resulting p‐n diode within the porous silicon is of a three‐dimensional nature and exhibits an extremely high internal surface area up to ∼6690 cm2/cm3. To our knowledge, this is the first use of such a technique to fabricate conformal, three‐dimensional p‐n junctions for photovoltaic applications. The large internal surface area of this diode makes it applicable to next generation photovoltaics. Moreover, the porous silicon within this device is not simply an antireflection coating; rather it is a light trapping medium that has the ability to become a large surface area diode and can serve as a host matrix for photoactive compounds. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Skin peptides from anurans of theLitoria rubellaGroup: sequence determination using electrospray mass spectrometry. Opioid activity of two major peptides
Authors: Jackway Rebecca J. , Maselli Vita M. , Musgrave Ian F. , Maclean Micheal J. , Tyler Michael J. , Bowie John H.
Published: March 2009

Many species of frogs of the genusLitoriasecrete bioactive peptides from their skin glands. These peptides are normally host‐defence compounds and may have one, or more of the following activities; smooth muscle contraction, analgesic, antimicrobial, antiviral, lymphocyte proliferator (immunomodulator) and neuronal nitric oxide synthase (nNOS) inactivation. Two frog species of theLitoria rubellaGroup that have been studied before, namely,Litoria electricaandLitoria rubella, are different from other species of the genusLitoriain that they produce small peptides that show neither membrane, lymphocyte nor nNOS activity. In this study we have used electrospray mass spectrometry together with Edman sequencing to identify eight skin peptides of the third member of this Group,Litoria dentata: surprisingly, none of these peptides show activity in our biological screening program. However, two major peptides (FPWL‐NH2and FPWP‐NH2) fromL. electricaandL. rubellaare opioids at the micromolar concentration. Copyright © 2009 John Wiley & Sons, Ltd.
Computer‐assisted therapy in orbital and mid‐facial reconstructions
Authors: Schramm A. , Suarez‐Cunqueiro M. M. , Rücker M. , Kokemueller H. , Bormann K.‐H. , Metzger M. C. , Gellrich N.‐C.
Published: March 2009

Background

Management of orbital and mid‐facial fractures requires a thorough ophthalmic evaluation and precise imaging. A principle goal of therapy is to anatomically reduce fracture segments and to restore a normal orbital volume as soon as possible. Diagnostic advances such as new surgical and imaging techniques have dramatically improved both the functional and aesthetic outcome of reconstructions.

Methods

Orbital reconstruction is performed using computer‐assisted navigation. This technique makes preoperative simulation by mirroring the unaffected side onto the affected side.

Results

Results from computer‐assisted navigation application to both primary and secondary orbital and mid‐facial reconstruction are shown.

Conclusion

Navigation technique it offers significant advantages in both primary and secondary reconstructions. Navigation facilitates reconstruction in unilateral defects through mirroring techniques, and in bilateral defects by importing virtual models from standard CT datasets improving the software tool to fulfil the need for maxillofacial surgery reconstruction. Copyright © 2009 John Wiley & Sons, Ltd.
Surface analysis of nitride layers formed on Fe‐based alloys through plasma nitride process
Authors: Sato Shigeo , Omori Koji , Araki Sawa , Takahashi Yohei , Wagatsuma Kazuaki
Published: March 2009

Nitriding phenomena that occur on the surfaces of pure Fe and FeCr alloy (16 wt% Cr) samples were investigated. An Ar + N2 mixture‐gas glow‐discharge plasma was used so that surface nitriding could occur on a clean surface etched by Ar+ ion sputtering. In addition, the metal substrates were kept at a low temperature to suppress the diffusion of nitrogen. These plasma‐nitriding conditions enabled us to characterize the surface reaction between nitrogen radicals and the metal substrates. The emission characteristics of the band heads of the nitrogen molecule ion (N2+) and nitrogen molecule from the glow‐discharge plasma suggest that the active nitrogen molecule is probably the major nitriding reactant. AES and angle‐resolved XPS were used to characterize the thickness of the nitride layer and the concentration of elements and chemical species in the nitride layer. The thickness of the nitride layer did not depend on the metal substrate type. An oxide layer with a thickness of a few nanometers was formed on the top of the nitride layer during the nitriding process. The oxide layer consisted of several species of Nx‐Fey‐O, NO+, and NO2−. In the FeCr alloy sample, these oxide species could be reduced because chromium is preferentially nitrided. Copyright © 2009 John Wiley & Sons, Ltd.
Development of a low‐energy x‐ray fluorescence system with sub‐micrometer spatial resolution
Authors: Alberti R. , Klatka T. , Longoni A. , Bacescu D. , Marcello A. , De Marco A. , Gianoncelli A. , Kaulich B.
Published: March 2009

We report on a low‐energy x‐ray fluorescence (LEXRF) spectrometer system implemented in the European TwinMic x‐ray spectromicroscope,1which is operated in the 280–2200 eV energy range and allows sub‐100 nm optical resolution by means of focusing with diffractive optics. The LEXRF setup is a modular system based on the use of multiple windowless large‐area silicon drift detectors (SDD). The detectors are read out by a custom pulsed reset preamplifier system optimized for SDDs and specially designed and adapted to geometrical requirements for microscopies at synchrotron facilities. Moreover, a customized fast multi‐channel acquisition system developed for elemental mapping applications has been adapted to the microscope requirements. Acquisition of elemental composition by LEXRF maps is accomplished by simultaneous acquisition of absorption and phase contrast images to correlate the morphological structure. The instrumental setup is described and its potential illustrated by recently performed pilot experiments. Copyright © 2009 John Wiley & Sons, Ltd.
The necessity of maximum information utilization in x‐ray analysis
Authors: Papp T. , Maxwell J. A. , Papp A. T.
Published: March 2009

There are significant discrepancies in the experimental data needed in the analysis of x‐ray spectra. Examination of the data in detail shows that they often contradict simple logic, elemental arithmetic, even parity and angular momentum conservation laws. We have identified that the main source of the problems, other than the human factor, is rooted in the signal processing electronics. We have developed a line of fully digital signal processors that not only have excellent resolution and line shape but also allow proper accounting. We achieve this by processing all events and separating them into two or more spectra where the first spectrum is the accepted or good spectrum and the second spectrum is the rejected spectrum. It is not enough to know that an event was rejected, and increment the input counter—it is necessary to know what happened and why, whether it was pure noise, a noisy or disturbed event, a true event, or any pile up combination of the above in order to account properly for true event input rate and processor dead time. The data processing methodology cannot be reliably established on the partial and fractional information offered by other approaches. The availability of all the events allows one to see the other part of the spectrum. To our surprise the total information explains many of the shortcomings and contradictions of the x‐ray database. We call this a maximum information utilization approach in signal processing. Also a fundamental parameter x‐ray fluorescence analysis program (CSX‐XRF) has been developed to utilize all the information offered by the signal processor. The fundamental parameter method is only as good as the database it uses and the description of the x‐ray fluorescence analysis system. This latter poses significant difficulties, and to ease the demand we have developed an inverse fundamental parameter program package for x‐ray tube based equipment characterization. Copyright © 2009 John Wiley & Sons, Ltd.
Algebra and logic for access control
Authors: Collinson Matthew , Pym David
Published: March 2009

The access control problem in computer security is fundamentally concerned with the ability of system entities to see, make use of, or alter various system resources. We provide a mathematical framework for modelling and reasoning about (distributed) systems with access control. This is based on a calculus of resources and processes together with a Hennessy–Milner-style modal logic, based on the connectives of bunched logic, for which an appropriate correspondence theorem obtains. As a consequence we get a consistent account of both operational behaviour and logical reasoning for systems with access control features. In particular, we are able to introduce a process combinator that describes, as a form of concurrent composition, the action of one agent in the role of another, and provide a logical characterization of this operator via a modality ‘says’. We give a range of examples, including analyses of co-signing, roles, and chains of trust, which illustrates the utility of our mathematical framework.
Burden of Surgical Disease: Does the Literature Reflect the Scope of the International Crisis?
Authors: Taira Breena R. , Kelly McQueen K. A. , Burkle Frederick M.
Published: March 2009

Background

Little is factually known about the burden of surgical disease and less is known about global surgical provision of care for diseases that may be treated, cured, or palliated by a surgical intervention. Despite the lack of information, surgical interventions are provided by a variety of agencies every day in the developing world. This literature review represents the first published comprehensive review of the global surgical literature. The primary goal was to collect and summarize what has been published on the current global burden of surgical disease and thereby encourage and promote the allocation of further research and resources.

Methods

A systematic review of English language publications on Pubmed or Medline was performed.

Results and conclusions

This report summarizes what little is known in terms of numeric estimates for the global burden of surgical disease. Globally, access and availability of surgical care in developing countries remains scarce, but the problem is receiving more attention for the first time in surgical circles. Much work remains in the effort to obtain reliable estimates of the global burden of surgical disease.
The use of melodic formulas in responsories: constancy and variability in the manuscript tradition
Authors: Helsen Kate
Published: March 2009

The basis of this study comes from the great responsory repertory in the twelfth-century French monastic manuscript, Paris 12044 from Saint-Maur-des-Fossés. A computerised database containing each component phrase was used to create a more accurate melodic taxonomy of responsories than has hitherto been available. Building on the research of W.H. Frere, H-J. Holman, and others, it is possible to obtain clearer insight into formulaic composition in an oral culture. This is achieved by comparing the use of recurrent, or ‘standard’, musical material in Paris 12044 to that found in several other manuscripts. The presence of standard material in a respond melody is found to be linked to the consistency of form and tonal structure.
Detector Solid Angle Formulas for Use in X-Ray Energy Dispersive Spectrometry
Authors: Zaluzec Nestor J.
Published: March 2009

With the advent of silicon drift X-ray detectors, a range of new geometries has become possible in electron optical columns. Because of their compact size, these detectors can potentially achieve high geometrical collection efficiencies; however, using traditional approximations detector solid angle calculations rapidly break down and at times can yield nonphysical values. In this article we present generalized formulas that can be used to calculate the variation in detection solid angle for contemporary Si(Li) as well as new silicon drift configurations.
Ultrastructure of the Epithelial Cells Associated with Tooth Biomineralization in the ChitonAcanthopleura hirtosa
Authors: Shaw Jeremy A. , Macey David J. , Brooker Lesley R. , Stockdale Edward J. , Saunders Martin , Clode Peta L.
Published: March 2009

The cusp epithelium is a specialized branch of the superior epithelium that surrounds the developing teeth of chitons and is responsible for delivering the elements required for the formation of biominerals within the major lateral teeth. These biominerals are deposited within specific regions of the tooth in sequence, making it possible to conduct a row by row examination of cell development in the cusp epithelium as the teeth progress from the unmineralized to the mineralized state. Cusp epithelium from the chitonAcanthopleura hirtosawas prepared using conventional chemical and microwave assisted tissue processing, for observation by light microscopy, conventional transmission electron microscopy (TEM) and energy filtered TEM. The onset of iron mineralization within the teeth, initiated at row 13, is associated with a number of dramatic changes in the ultrastructure of the apical cusp cell epithelium. Specifically, the presence of ferritin containing siderosomes, the position and number of mitochondria, and the structure of the cell microvilli are each linked to aspects of the mineralization process. These changes in tissue development are discussed in context with their influence over the physiological conditions within both the cells and extracellular compartment of the tooth at the onset of iron mineralization.
Composition of matter in the heliosphere
Authors: Bochsler Peter
Published: March 2009

The Sun is by far the largest reservoir of matter in the solar system and contains more than 99% of the mass of the solar system. Theories on the formation of the solar system maintain that the gravitational collapse is very efficient and that typically not more than one tenth from the solar nebula is lost during the formation process. Consequently, the Sun can be considered as a representative sample of interstellar matter taken from a well mixed reservoir 4.6 Gy ago, at about 8 kpc from the galactic center. At the same time, the Sun is also a faithful witness of the composition of matter at the beginning of the evolution of the solar system and the formation of planets, asteroids, and comets. Knowledge on the solar composition and a fair account of the related uncertainties is relevant for many fields in astrophysics, planetary sciences, cosmo- and geochemistry. Apart from the basic interest in the chemical evolution of the galaxy and the solar system, compositional studies have also led to many applications in space research, i.e., it has helped to distinguish between different components of diffuse heliospheric matter. The elemental, isotopic, and charge state composition of heliospheric particles (solar wind, interstellar neutrals, pickup ions) has been used for a multitude of applications, such as tracing the source material, constraining parameters for models of the acceleration processes, and of the transport through the interplanetary medium. It is important to realize, that the two mainstream applications, as outlined above – geochemistry and cosmochemistry on one side, and tracing of heliospheric processes on the other side – are not independent of each other. Understanding the physical processes, e.g., of the fractionation of the solar wind, is crucial for the interpretation of compositional data; on the other hand, reliable information on the source composition is the basis for putting constraints on models of the solar wind fractionation.
Coronal shocks associated with CMEs and flares and their space weather consequences
Authors: Laskari Marina , Preka-Papadema Panagiota , Caroubalos Constantine , Pothitakis George , Moussas Xenophon , Mitsakou Eleftheria , Hillaris A.
Published: March 2009

We study the geoeffectiveness of a sample of complex events; each includes a coronal type II burst, accompanied by a GOES SXR flare and LASCO CME. The radio bursts were recorded by the ARTEMIS-IV radio spectrograph, in the 100-650 MHz range; the GOES SXR flares and SOHO/LASCO CMEs, were obtained from the Solar Geophysical Data (SGD) and the LASCO catalogue respectively. These are compared with changes of solar wind parameters and geomagnetic indices in order to establish a relationship between solar energetic events and their effects on geomagnetic activity.
Possible heliogeophysical effects on human physiological state
Authors: Dimitrova Svetla
Published: March 2009

A group of 86 healthy volunteers was examined in periods of high solar and geomagnetic activity. In this study hourly Dst-index values and hourly data about intensity of cosmic rays were used. Results revealed statistically significant increments for the mean systolic and diastolic blood pressure, pulse pressure and subjective psycho-physiological complaints of the group with geomagnetic activity increase and cosmic rays intensity decrease.
Solar oscillations
Authors: Antia H. M.
Published: March 2009

Study of solar oscillations has provided us detailed information about solar structure and dynamics. These in turn provide a test of theories of stellar structure and evolution as well as theories of angular momentum transfer and dynamo. Some of these results about the solar structure and its implication on the recent revision of heavy element abundances are described. Apart from these the solar cycle variations in the rotation rate and its gradients are also discussed.
A study of spicules from space observations
Authors: Kontogiannis Ioannis , Tsiropoula Georgia , Tziotziou Kostas
Published: March 2009

We have studied spicules observed at the northern solar limb by using simultaneous high resolution image sequences. The images were obtained by Hinode/SOT (in the Ca II H passband) and TRACE (in the 1600 Å passband) during a coordinated campaign. Both data sets were reduced and then carefully co-aligned in order to compare the observed patterns in this highly dynamic region of the Sun. The identification of individual structures in both spectral bands allows us to trace their spatial and temporal behaviour. Persistent intensity variations at certain locations, indicate that at least some spicules have a recurrent behavior. Using wavelet analysis we investigate oscillatory phenomena along the axis of off-limb spicules and we construct 2-D maps of the solar limb with the observed oscillations.
Solar Differential Rotation of Compact Magnetic Elements and Polarity Reversal of the Sun
Authors: Japaridze Darejan , Gigolashvili Marina , Kukhianidze Vasili
Published: March 2009

The differential rotation of the compact elements of the large-scale magnetic fields is studied using Solar Synoptic Charts (1966–1986). It is revealed that compact magnetic elements with the similar polarity of the polar magnetic field of the Sun have a larger rotation rate than the elements with the opposite polarity at all stages in the cycle.

From the comparison of the experimental measuring data of the solar magnetic elements there are received the results: a) The differential rotations of the compact magnetic elements with negative and positive polarities have the similar behavior for the solar 20 and 21 cycles; b) It is established that in the rotation rate of compact magnetic elements there are present some variations at the time of polarity reversal of the Sun.

There is assumed that the physical understanding of the connections of differential rotation of compact magnetic elements and polarity reversal of the Sun depends upon establishing a connection between the temporal variability of spatially resolved solar magnetic elements and polar reversals.
Coronal waves in coronal loops during non-flare stage
Authors: Prosovetsky Dmitry
Published: March 2009

Using SOHO/EIT Fe XII λ195 Å observations the new type of oscillations in coronal loops was detected. The oscillation corresponds to wave propagated to outer area of atmosphere of active area. As opposed to most kind of oscillations associated with coronal loops the waves are observed at non-flare stage of active areas evolution. Velocities of the wave propagation were 8-20 km s−1 and had quasi-perpendicular direction with magnetic field. Such waves were detected in active areas located on solar disk and loops structures outside solar limb. Investigation of EIT data shows the waves are not result of changes of topology of a magnetic field and loops configuration. The nature and probable sources of waves are discussed.
The expansion of a coronal mass ejection within LASCO field of view: some regularities
Authors: Fainshtein V. G.
Published: March 2009

Forty five limb CMEs related with eruptive prominences and/or near-to-limb post-eruptive arcades have been tested. It is shown that CMEs can be divided into two groups. The first group includes coronal mass ejections whose “2α” latitude angular sizes apparent in the plane of the sky remain unchanged within measurement accuracy of several degrees. The second one is formed by CMEs that expand “non-radially”, namely, their angular sizes increase by the relative value (10-30)% up to the position of the ejection front RF = Rαm and run to the maximal value 2αm at this distance. It has been found that CMEs of the second type are, on the average, wider, faster and have an outer shell brighter and with higher plasma density for long distances. It is shown that on average Rαm increases as 2αm rises.
The role of aerodynamic drag in dynamics of coronal mass ejections
Authors: Vršnak Bojan , Vrbanec Dijana , Čalogović Jaša , Žic Tomislav
Published: March 2009

Dynamics of coronal mass ejections (CMEs) is strongly affected by the interaction of the erupting structure with the ambient magnetoplasma: eruptions that are faster than solar wind transfer the momentum and energy to the wind and generally decelerate, whereas slower ones gain the momentum and accelerate. Such a behavior can be expressed in terms of “aerodynamic” drag. We employ a large sample of CMEs to analyze the relationship between kinematics of CMEs and drag-related parameters, such as ambient solar wind speed and the CME mass. Employing coronagraphic observations it is demonstrated that massive CMEs are less affected by the aerodynamic drag than light ones. On the other hand, in situ measurements are used to inspect the role of the solar wind speed and it is shown that the Sun-Earth transit time is more closely related to the wind speed than to take-off speed of CMEs. These findings are interpreted by analyzing solutions of a simple equation of motion based on the standard form for the drag acceleration. The results show that most of the acceleration/deceleration of CMEs on their way through the interplanetary space takes place close to the Sun, where the ambient plasma density is still high. Implications for the space weather forecasting of CME arrival-times are discussed.
Dynamics of interplanetary CMEs and associated type II bursts
Authors: Lara Alejandro , Borgazzi Andrea I.
Published: March 2009

Coronal mass ejections (CMEs) are large scale structures of plasma (~1016g) and magnetic field expelled from the solar corona to the interplanetary medium. During their travel in the inner heliosphere, these “interplanetary CMEs” (ICMEs), suffer acceleration due to the interaction with the ambient solar wind. Based on hydrodynamic theory, we have developed an analytical model for the ICME transport which reproduce well the observed deceleration of fast ICMEs. In this work we present the results of the model and its application to the CME observed on May 13, 2005 and the associated interplanetary type II burst.
The heliosphere mass variations: 1996–2006
Authors: Pintér T. , Dorotovič I. , Rybanský M.
Published: March 2009

The variations of the global mass of heliosphere in the 23rd cycle of the solar activity are described. The results are derived from solar corona observations and from ‘in situ’ measurements made by the space probes SOHO, VOYAGER2, ACE, WIND, and ULYSSES. It has been revealed that though the total mass of corona fluctuates during the solar activity cycle approximately in a ratio of 1 : 3, the specific mass flow (q) in the solar wind does not change in the ecliptic plane. In the polar regions the q decreases during the minimum in a third of the original value and the velocity of expansion is roughly double. These findings are valid for the 23rd solar cycle.
Localization of type II and type III radio burst sources using multi-spacecraft observations
Authors: Thejappa G. , MacDowall R. J.
Published: March 2009

A method for the localization of the radio burst sources associated with the flare accelerated electron beams and coronal mass ejection (CME) shocks is presented. This method involves the computations of the ray trajectories, time delays, and optical depths in the refracting solar atmosphere. The coordinates of the radiating source can be obtained by comparing the time delays and intensity ratios of the bursts observed by widely separated spacecraft with the computed group delays and intensity ratios at exit points of the rays from the solar atmosphere. This method is applied to a type III radio burst observed by the STEREO spacecraft.
Fragmented type II burst emission during CME liftoff
Authors: Pohjolainen Silja , Pomoell Jens , Vainio Rami
Published: March 2009

We have performed multiwavelength analysis on an event with a metric type II burst, which appeared first as fragmented emission lanes in the radio dynamic spectrum. The start frequency was unusually high. Since type II bursts are thought to be signatures of propagating shock waves, it is of interest to know how the shocks, and the type II bursts, are formed. This radio event was associated with a flare and a coronal mass ejection (CME), and we investigate their connection. Observations suggested that a propagating shock was formed due to the erupting structures, and the observed radio emission reflects the high densities in active region loops. We then utilised numerical MHD simulations, to study the shock structure induced by an erupting CME, in a model corona including dense loops. Our simulations show that the fragmented part of the type II burst can be formed when a coronal shock driven by a CME passes through a system of dense loops overlying an active region. To produce fragmented emission, the conditions for plasma emission have to be more favourable inside the loop than in the inter-loop area. The obvious hypothesis, consistent with our simulation model, is that the shock strength decreases significantly in the space between the denser loops. Outside the active region, the type II burst dies out when the changing geometry no longer favours the electron shock-acceleration.
Cosmic ray modulation by corotating interaction regions
Authors: Čalogović Jaša , Vršnak Bojan , Temmer Manuela , Veronig Astrid M.
Published: March 2009

We analyzed the relationship between the ground-based modulation of cosmic rays (CR) and corotating interaction regions (CIRs). Daily averaged data from 8 different neutron monitor (NM) stations were used, covering rigidities from Rc = 0 − 12.91 GeV. The in situ solar wind data were taken from the Advanced Composition Explorer (ACE) database, whereas the coronal hole (CH) areas were derived from the Solar X-Ray Imager onboard GOES-12. For the analysis we have chosen a period in the declining phase of solar cycle 23, covering the period 25 January–5 May 2005. During the CIR periods CR decreased typically from 0.5% to 2%. A cross-correlation analysis showed a distinct anti-correlation between the magnetic field and CR, with the correlation coefficient (r) ranging from −0.31 to −0.38 (mean: −0.36) and with the CR time delay of 2 to 3 days. Similar anti-correlations were found for the solar wind density and velocity characterized by the CR time lag of 4 and 1 day, respectively. The relationship was also established between the CR modulation and the area of the CIR-related CH with the CR time lag of 5 days after the central-meridian passage of CH.
Theory of cosmic ray modulation
Authors: Ferreira Stefan E. S.
Published: March 2009

This work aims to give a brief overview on the topic of cosmic ray modulation in the heliosphere. The heliosphere, heliospheric magnetic field, transport parameters and the transport equation together with modulation models, which solve this equation in various degree of complexity, are briefly discussed. Results from these models are then presented where first it is shown how cosmic rays are globally distributed in an asymmetrical heliosphere which results from the relative motion between the local interstellar medium and the Sun. Next the focus shifts to low-energy Jovian electrons. The intensities of these electrons, which originate from a point source in the inner heliosphere, exhibit a unique three-dimensional spiral structure where most of the particles are transported along the magnetic field lines. Time-dependent modulation is also discussed where it is shown how drift effects together with propagating diffusion barriers are responsible for modulation over a solar cycle.
Anomalous Forbush effects from sources far from Sun center
Authors: Eroshenko E. , Belov A. , Mavromichalaki H. , Oleneva V. , Papaioannou A. , Yanke V.
Published: March 2009

The Forbush effects associated with far western and eastern powerful sources on the Sun that occurred on the background of unsettled and moderate interplanetary and geomagnetic disturbances have been studied by data from neutron monitor networks and relevant measurements of the solar wind parameters. These Forbush effects may be referred to a special sub-class of events, with the characteristics like the event in July 2005, and incorporated by the common conditions: absence of a significant disturbance in the Earth vicinity; absence of a strong geomagnetic storm; slow decrease of cosmic ray intensity during the main phase of the Forbush effect. General features and separate properties in behavior of density and anisotropy of 10 GV cosmic rays for this subclass are investigated.
History of the solar environment
Authors: Marti Kurt , Lavielle Bernard
Published: March 2009

Galactic cosmic rays (GCR) provide information on the solar neighborhood during the sun's motion in the galaxy. There is now considerable evidence for GCR acceleration by shock waves of supernova in active star-forming regions (OB associations) in the galactic spiral arms. During times of passage into star-forming regions increases in the GCR-flux are expected. Recent data from the Spitzer Space Telescope (SST) are shedding light on the structure of the Milky Way and of its star-forming-regions in spiral arms. Records of flux variations may be found in solar system detectors, and iron meteorites with GCR-exposure times of several hundred million years have long been considered to be potential detectors (Voshage, 1962). Variable concentration ratios of GCR-produced stable and radioactive nuclides, with varying half-lives and therefore integration times, were reported by Lavielleet al. (1999), indicating a recent 38% GCR-flux increase. Potential flux recorders consisting of different pairs of nuclides can measure average fluxes over different time scales (Lavielleet al., 2007; Mathew and Marti, 2008). Specific characteristics of two pairs of recorders (81Kr-Kr and129I-129Xe) are the properties of self-correction for GCR-shielding (flux variability within meteorites of varying sizes). The81Kr-Kr method (Marti, 1967) is based on Kr isotope ratios, while stable129Xe is the decay product of the radionuclide129I, which is produced by secondary neutron reactions on Te in troilites of iron meteorites. The two chronometers provide records of the average GCR flux over 1 and 100 million year time scales, respectively.
Multi-spacecraft observations to study the shock extension in the inner heliosphere
Authors: de Lucas Aline , Schwenn Rainer , Marsch Eckart , Lago Alisson Dal , de Gonzalez Alicia L. Clúa , Echer Ezequiel , Gonzalez Walter D. , da Silva Marlos R.
Published: March 2009

The two Helios probes traveled at variable longitudinal and radial separations through the inner heliosphere. They collected most valuable high resolution plasma and magnetic field data for an entire solar cycle. The mission is still so successful that no other missions will collect the same kind of data in the next 20 years. One of the subjects studied after the success of the Helios mission was the identification of more than 390 shock waves driven by Interplanetary Coronal Mass Ejections (ICMEs). Combining the data from both probes, we make a statistical study for the extension of the shock waves in the interplanetary medium. For longitudinal separations of 90° we found a cutoff value at this angular separation. A shock has 50% of chance to be observed by both probes and the same probability for not being observed by two spacecrafts at the same time, when the angle between them is around 90°. We describe the dependence of the probability for shocks to be observed by both probes with decreasing spacecraft separation. Including plasma data from the ISEE-3 and IMP-8 spacecrafts improves our statistical evaluation substantially.
Evolution of stellar winds from the Sun to red giants
Authors: Suzuki Takeru K.
Published: March 2009

By performing global 1D MHD simulations, we investigate the heating and acceleration of solar and stellar winds in open magnetic field regions. Our simulation covers from photosphere to 20-60 stellar radii, and takes into account radiative cooling and thermal conduction. We do not adopt ad hoc heating function; heating is automatically calculated from the solutions of Riemann problem at the cell boundaries. In the solar wind case we impose transverse photospheric motions with velocity ~1 km/s and period between 20 seconds and 30 minutes, which generate outgoing Alfvén waves. We have found that the dissipation of Alfvén waves through compressive wave generation by decay instability is quite effective owing to the density stratification, which leads to the sufficient heating and acceleration of the coronal plasma. Next, we study the evolution of stellar winds from main sequence to red giant phases. When the stellar radius becomes ~10 times of the Sun, the steady hot corona with temperature 106K, suddenly disappears. Instead, many hot and warm (105– 106K) bubbles are formed in cool (T< 2 × 104K) chromospheric winds because of the thermal instability of the radiative cooling function; the red giant wind is not a steady stream but structured outflow.
A new spatial distribution map of δ18O in Antarctic surface snow
Authors: Wang Yetang , Hou Shugui , Masson‐Delmotte Valérie , Jouzel Jean
Published: March 2009

We developed a gridded map of surface Antarctic snow isotopic composition using a recently compiled database and the modified Bowen and Wilkinson (2002) model using latitude and elevation as the primary predictors while also incorporating regional and local deviations based on available isotopic data. The map was generated using a 1‐km digital elevation model grid data as the model input. The average of the absolute deviations between observations and predictions was about 0.8‰, and the standard deviation is 0.9‰. The resulting δ18O patterns reproduced correctly spatial isotopic gradients with respect to geographical characteristics, as well as climatic features.
An asymmetry correction method for ionospheric radio occultation
Authors: Wu Xiaocheng , Hu Xiong , Gong Xiaoyan , Zhang Xunxie , Wang Xin
Published: March 2009

The approximation of spherical symmetry of electron density is the main error source in the inversion of ionospheric radio occultation (IRO). The study in this paper shows that only even terms of the asymmetry contribute to the inversion error. An asymmetry factor for IRO is defined, and it is approximately equal to the relative error of the inversion result. The characteristics of the asymmetry factor are studied and are shown in the following: (1) the absolute value of asymmetry factor (AVAF) of a zonal occultation is much smaller than that of the meridian one; (2) higher solar activity corresponds to larger AVAF; (3) AVAF is largest in winter, second largest in equinox season, and smallest in summer; and (4) generally, AVAF at middle geomagnetic latitudes is smaller than at other latitudes, and it is large at the magnetic equator, the crest region, and the middle‐latitude trough. The asymmetry factor is applied to correct the retrieved electron density, and the inversion error is greatly reduced.