bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions of dextran sulfates with granulocyte colony‐stimulating factor and their effects on leukemia cells
Authors: Liang Aiye , Zhou Xiaomian , Wang Qiuyan , Liu Xin , Qin Jianhua , Du Yuguang , Wang Keyi , Lin Bingcheng
Published: August 2006

The interactions between granulocyte colony‐stimulating factor (G‐CSF) and dextran sulfate (DS) with different chain lengths and sulfate contents were studied by capillary zone electrophoresis. It was found that DS with a molecular mass of 500 kDa (DS500) could bind to G‐CSF and the binding constant and binding sites were determined using Scatchard plot to be 1.17×106 M−1 and 3, respectively. DS with a molecular mass of 40 kDa also had the affinity to G‐CSF and the binding constant and binding sties were 1.01×106 M−1 and 8, respectively. However, DS with a molecular mass of 8 kDa and the non‐sulfated saccharide, dextran, had no affinity to G‐CSF. The results indicate that the interactions between G‐CSF and DS are dependent on the chain lengths and sulfate contents of the saccharides. In addition, the effects of G‐CSF‐binding DS on a G‐CSF‐dependent leukemia cell line were investigated using biological methods. Results show that DS500 plus G‐CSF has potential therapeutic effect on cancers because their combination could inhibit the growth and induce the differentiation of the leukemia cells.
Study of SU‐8 to make a Ni master‐mold: Adhesion, sidewall profile, and removal
Authors: Kim Sung‐Jin , Yang Haesik , Kim Kyuwon , Lim Yong Taik , Pyo Hyeon‐Bong
Published: August 2006

For disposable microfluidic devices, easy and inexpensive fabrication is essential. Consequently, replication of microfluidic devices, using injection molding or hot embossing, from a master‐mold is widely used. However, the conventional master‐mold fabrication technique is unsatisfactory in terms of time and costs. In this regard, direct Ni growth (electroplating) from a back plate is promising when the photoresist is well‐defined. Here, we demonstrate the use of SU‐8 as a photoresist to define the Ni‐growth region. We accomplish this application by focusing on the adhesion, the sidewall profile, and the removal of SU‐8: the adhesion is enhanced by controlling the exposure dose, the soft‐baking time, and by choosing the adhesion‐promoting layer; the sidewall profile is regulated by selecting the intensity of each exposed wavelength, showing an aspect ratio of up to 20.9; and, easy removal is achieved by choosing a proper photoresist‐stripper. Using the master‐mold fabricated by this method, we test the mechanical stability of the features according to the aspect ratio and length; in the hot embossing process, the features are stable in the aspect ratio of up to 5.8 at a length of 200 µm. In addition, the plastic devices fabricated from this method are applied to the passive stop valves, showing a capillary pressure (−0.2 to −7.2 kPa).
Quantitative analysis of DNA‐protein interactions using double‐labeled native gel electrophoresis and fluorescence‐based imaging
Authors: Forwood Jade K. , Jans David A.
Published: August 2006

We have developed a sensitive, non‐radioactive method to assess the interaction of transcription factors/DNA‐binding proteins with DNA. We have modified the traditional radiolabeled DNA gel mobility shift assay to incorporate a DNA probe end‐labeled with a Texas‐red fluorophore and a DNA‐binding protein tagged with the green fluorescent protein to monitor precisely DNA‐protein complexation by native gel electrophoresis. We have applied this method to the DNA‐binding proteins telomere release factor‐1 and the sex‐determining region‐Y, demonstrating that the method is sensitive (able to detect 100 fmol of fluorescently labeled DNA), permits direct visualization of both the DNA probe and the DNA‐binding protein, and enables quantitative analysis of DNA and protein complexation, and thereby an estimation of the stoichiometry of protein‐DNA binding.
Effects of separation length and voltage on isoelectric focusing in a plastic microfluidic device
Authors: Das Champak , Fan Z. Hugh
Published: August 2006

This paper describes the investigation on the effects of separation length and voltage on IEF in a plastic microfluidic device. A LIF, whole‐channel imaging detection (WCID) system was developed to monitor proteins while they were moving under an electric field. IEF was carried out in a separation medium consisting of carrier ampholytes and a mixture of linear polymers (hydroxyethylcellulose and hydroxypropylcellulose). We found that the IEF separation resolution is essentially independent of separation length when the same voltage is applied, which agrees with the theory. This result supports the notion that IEF in a microfabricated device leads to more rapid analysis without sacrificing the resolving power. A higher separation voltage also brought about more rapid analysis and superior separation resolution. IEF of two proteins (green fluorescence protein and R‐phycoerythrin) was achieved in 1.5 min when 500 V was applied across a 1.9‐cm channel. We found that a linear relationship exists between the focusing time and the inverse of the electrical field strength. In addition, we confirmed the phenomenon in which the pH gradient was compressed to the middle of a channel, and we found that the relative amount of the gradient compression decreased with the channel length.
Surface plasmon resonance‐enabled mass spectrometry arrays
Authors: Nedelkov Dobrin , Tubbs Kemmons A. , Nelson Randall W.
Published: August 2006

Biosensors that utilize surface plasmon resonance (SPR) as a method of detection of protein interactions can be used for selective separation of proteins prior to MS analysis. The combination of SPR and MS results in a unique multiplexed detection technology capable of both quantitative and qualitative protein analysis. To further the development of a high‐throughput SPR‐MS approach, the possibility of arraying binding ligands on SPR chips for affinity capture of proteins and their MS analysis was explored. Antibodies to β‐2‐microglobulin, cystatin C, transferrin, and insulin‐like growth factors I and II were arrayed on a large number of SPR chips. Human plasma samples were injected over the antibody array chips in an SPR Biosensor, after which on‐chip MS analysis was performed to detect the bound proteins. Signals from the targeted proteins were observed for each antibody‐derivatized chip, indicating successful antibody immobilization and protein capture. The SPR‐MS arrays are robust, highly reproducible, and are capable of high‐throughput analysis.
Online concentration and separation of basic proteins using a cationic polyelectrolyte in the presence of reversed electroosmotic flow
Authors: Yu Cheng‐Ju , Tseng Wei‐Lung
Published: August 2006

We report an online concentration and separation method for basic proteins using poly(diallyldimethylammonium chloride) (PDDA) solutions in the presence of reversed EOF. Using a capillary dynamically coated with 2% PDDA containing 0.1 M NaCl and filled with 1.2% PDDA under neutral conditions (10 mM phosphate, pH 7.0), we have demonstrated the separation of six basic proteins with peak efficiencies ranging from 175 000 to 616 000 plates/m and RSDs of migration time less than 0.4%. Additionally, high‐speed separation of six basic proteins (<7 min) was achieved using a short capillary filled with 0.6% PDDA solutions. Under injection of the large‐volume sample (210 nL), the LODs at S/N of 3 for basic proteins are down to nanomolar range. For example, the LOD for lysozyme is 1.2 nM, which is a 260‐fold sensitivity enhancement compared with conventional injection method. The proposed method has been applied to the stacking of lysozyme in human saliva samples. Without any pretreatment, we also demonstrated the capability of this method to detect low amounts of peptide samples through the stacking of tryptic peptide of myoglobin. The experimental results indicate that our proposed method has great potential for use in clinical diagnosis and proteomics applications.
Evaluation of reactivation test in anaesthetized dogs with experimental intoxication with nerve agents
Authors: Bajgar J. , Fusek J. , Bartosova L. , Jun D. , Kuca K.
Published: August 2006

Following repeated antidotal treatment of anaesthetized dogs (1 min with atropine, 10 min with atropine and obidoxime, 60 min with atropine and obidoxime) after the intoxication with soman, sarin and VX (1 × LD50, i.m.), the blood cholinesterases (erythrocyte, whole blood, plasma) were monitored and their reactivatability (whole blood) was determined. During this treatment, the activities of erythrocyte acetylcholinesterase (AChE), plasma butyrylcholinesterase (BuChE) and whole blood cholinesterases were monitored. Atropine and obidoxime did not affect cholinesterase activities in control animals, whereas administration of obidoxime to dogs intoxicated with nerve agent caused an increase in the cholinesterase activities. The sensitivity of cholinesterases decreased in the order erythrocyte AChE > whole blood cholinesterases > plasma BuChE, respectively. Following sarin intoxication, blood cholinesterases were increased after the obidoxime administration. Intoxication with VX showed a similar picture but reactivation after the obidoxime administration was greater. In soman intoxication, the picture of cholinesterase changes was similar during the first 30 min of treatment. Then the increase in AChE activity following obidoxime administration was not as high as in the case of sarin and VX intoxication. Thus, the reactivation efficacy of obidoxime during nerve agent intoxication indicates that its repeated administration could be easily monitored using the reactivation test. Copyright © 2006 John Wiley & Sons, Ltd.
Historical shifts in the seed mineral micronutrient concentration of US hard red winter wheat germplasm
Authors: Garvin David F , Welch Ross M , Finley John W
Published: August 2006

The yield of wheat (Triticum aestivum L. em. Thell) has greatly improved through breeding, but it is not known how this has affected seed micronutrient content. In the present study, the iron (Fe), zinc (Zn), copper (Cu), and selenium (Se) content of seed of 14 US hard red winter wheat varieties from production eras spanning more than a century was measured. The seed that was analyzed was obtained from a replicated field trial conducted at two locations in Kansas. The Fe, Zn, and Cu content was obtained by inductively coupled plasma emission spectroscopy (ICPES) and Se content was obtained by hydride‐generated atomic absorption spectrometry (HG‐AAS). Significant effects of location on micronutrient content of seed were observed. Similarly, depending on the micronutrient, significant differences in seed micronutrient content between varieties were detected at one or both locations. A significant negative regression of seed Zn content on both yield and variety release date was observed at both locations, while seed Fe content exhibited a significant negative regression on yield and variety release date at one location. Regression of seed Se content on variety release date was significant and negative at one location. These results suggest that genetic gains in the yield of US hard red winter wheat have tended to reduce seed Fe, Zn, and Se concentrations. However, the extent to which this effect manifests itself is influenced by environmental effects. Published in 2006 by John Wiley & Sons, Ltd
Laser fluence and shot number dependence of laser-induced optical
properties modification of transparent materials
Authors: Jamshidi-Ghaleh K , Abdolahpour D , Mansour N
Published: August 2006

Micro-fabrication in transparent materials by
femtosecond laser-induced modification of the optical properties
inside transparent materials, preferentially optical glasses, has
received much attention. Ultra short laser pulses are capable of
inducing these modifications without cracking or even melting the
glasses. This kind of modification, which appears as darkening
inside glass relates to the trapped electrons or holes at defect
sites in the glass matrix. The femtosecond laser technology allows
controlling and modifying the optical properties of glasses on a
sub-micrometer scale. Laser fluence and laser shot number are
important parameters for femtosecond laser-induced modification of
glasses. This paper presents the 800 nm femtosecond laser-induced
optical modification inside soda lime glasses at different laser
fluence levels and laser shot numbers. Modification thresholds at
different applied laser fluences and shot numbers are measured.
Pulse energy accumulation model is proposed to predict the
behaviour of darkened area spots with applied laser fluence and
shot numbers. Our experimental results and the pulse energy
accumulation model are in good agreement.
Low Conversion 4‐Acetoxystyrene Free‐Radical Polymerization Kinetics Determined by Pulsed‐Laser and Thermal Polymerization
Authors: Li Ning , Cho Andrew S. , Broadbelt Linda J. , Hutchinson Robin A.
Published: August 2006

Summary: The free‐radical polymerization kinetics of 4‐acetoxystyrene (4‐AcOS) is studied over a wide temperature range. Pulsed‐laser polymerization, in combination with dual detector size‐exclusion chromatography, is used to measure kp, the propagation rate coefficient, between 20 and 110 °C. Values are roughly 50% higher than those of styrene, while the activation energy of 28.7 kJ · mol−1 is lower than that of styrene by 3–4 kJ · mol−1. With known kp, conversion and molecular weight data from 4‐AcOS thermal polymerizations conducted at 100, 140, and 170 °C are used to estimate termination and thermal initiation kinetics. The behavior is similar to that previously observed for styrene, with an activation energy of 90.4 kJ · mol−1 estimated for the third‐order thermal initiation mechanism.

Joint confidence (95%) ellipsoids for the frequency factor A and the activation energy Ea from non‐linear fitting of kp data for 4‐AcOS (black) and styrene (grey).

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Joint confidence (95%) ellipsoids for the frequency factor A and the activation energy Ea from non‐linear fitting of kp data for 4‐AcOS (black) and styrene (grey).
Interfacial Adhesion and Composite Viscoelasticity
Authors: Osman Maged A. , Atallah Ayman
Published: August 2006

Summary: The viscoelastic properties of 30 vol.‐% composites of calcite, surface‐treated with fatty acids of different chain length, and polyethylene were studied. The alkyl chains decrease the surface energy of the particles and the adhesion between the polymer and the filler. The moduli of the composites decrease with decreasing interfacial adhesion. When the shear forces applied overcome the adhesion forces, interfacial slippage takes place. Terminal OH groups in the alkyl chains enhance the particles' agglomeration, leading to a solid‐like response in the low frequency region. The presence of a plateau in the log moduli versus log frequency plot can be due to local structures and is not necessarily an evidence of a percolating filler network.

Steady shear viscosity (σ = 1 000 Pa) of 30 vol.‐% surface‐treated (different acids) CaCO3‐HDPE composites plotted as a function of the number of carbon atoms in the alkyl chains of the coated monolayer. The dotted line is simply a guide to the eye.

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Steady shear viscosity (σ = 1 000 Pa) of 30 vol.‐% surface‐treated (different acids) CaCO3‐HDPE composites plotted as a function of the number of carbon atoms in the alkyl chains of the coated monolayer. The dotted line is simply a guide to the eye.
Step‐by‐Step Synthesis of Monodisperse Methacrylamidoalkyl Oligolactates
Authors: Rijcken Cristianne J. F. , Leemhuis Mark , Veldhuis Theo F. J. , Hennink Wim E. , van Nostrum Cornelus F.
Published: August 2006

Summary: This paper describes the facile step‐by‐step synthesis to graft lactic acid or lactoyl lactate onto primary as well as secondary alcohol derivatives of methacrylamides via esterification. Elongation of the chains is achieved by repeating the coupling reactions with either hydroxyl‐protected monolactate or hydroxyl‐protected dilactate, followed by mild deprotection using tetrabutylammonium fluoride. This versatile synthesis route generates, on a multi‐gram scale, monodisperse oligolactates of predetermined lengths with functional end groups. The products can be used, for example, as building blocks for biodegradable polymeric materials.

The synthesis of monodisperse oligo(lactic acids) with methacrylamide end groups and a predefined number of lactic acid units.

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The synthesis of monodisperse oligo(lactic acids) with methacrylamide end groups and a predefined number of lactic acid units.
Tumor cell specific toxicity of Inula helenium extracts
Authors: Dorn David C. , Alexenizer Maja , Hengstler Jan G. , Dorn August
Published: August 2006

The aim of the research program was to identify botanical extracts with antineoplastic activity. In this respect extracts prepared from Inula helenium roots showed a remarkable activity. As evidenced by the MTT assay, the Inula helenium extract revealed a highly selective toxicity toward four different tumor cell lines (HT‐29, MCF‐7, Capan‐2 and G1), but a much lower toxicity against healthy human peripheral blood lymphocytes (PBLs) from two donors. The extract‐induced death of tumor cells was studied extensively by electron microscopy. There was a remarkable similarity of morphological alterations observed in the four cell lines: patchy chromatin condensations, cytoplasmic vesiculation, swelling and rupture of mitochondria. The morphology of cellular breakdown bore more resemblance to necrotic than to apoptotic cell death, which was supported by the failure to mark early apoptotic events by Annexin V. It has been pointed out recently that compounds inducing cell death with necrotic‐like morphology could be very beneficial in cases where cancerous cells have gained resistance to apoptosis. In this context, the remarkable difference in cytotoxicity exerted by the Inula helenium extract, which was over 100‐times higher in the tumor cell lines than in the PBLs, makes the extract an excellent candidate for further anticancerous investigations, especially since the Inula helenium extract was not mutagenic in the Ames test. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of perfluorooctanoic acid and perfluorooctanesulfonate in human tissues by liquid chromatography/single quadrupole mass spectrometry
Authors: Maestri Luciano , Negri Sara , Ferrari Massimo , Ghittori Sergio , Fabris Francesca , Danesino Paolo , Imbriani Marcello
Published: August 2006

A method is described that permits the measurement of the levels of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in human liver, kidney, adipose tissue, brain, basal ganglia, hypophysis, thyroid, gonads, pancreas, lung, skeletal muscle and blood, even in subjects not occupationally exposed to these compounds. The purification of samples involved the use of trifunctional (tC18) and strong anion‐exchange (SAX) solid‐phase extraction cartridges, and the analysis utilized a high‐performance liquid chromatograph coupled to a single quadrupole mass spectrometer (LC/MS). The analyses were conducted on a mixed‐bed reversed‐phase column by gradient runs using 3 mM ammonium acetate/methanol mixtures at different proportions as the mobile phase. The detector was used in electrospray negative ion mode by recording simultaneously the ions m/z 413.0 (PFOA) and 499.0 (PFOS). Perfluorononanoic acid (PFNA), added to the samples before the purification, was used as the internal standard (ion monitored = m/z 463.6). The recovery rates of the extraction procedure ranged from 79.6 to 95.6% (CV% 1.7–7.4%) for PFOA, from 79.7 to 100.8% (CV% = 1.2–7.1) for PFOS, and from 89.1 to 102.3% (CV% = 0.9–5.2 %) for PFNA. The calibration curves were linear up to at least 400 ng of analytes per gram of tissue. The detection limits (signal‐to‐noise ratio = 3) were 0.1 ng/g for both PFOA and PFOS measured in all tissues except adipose tissue, where the limits were about 0.2 ng/g. The content of analytes in tissues varied from 0.3 to 3.8 ng/g (respectively: basal ganglia and lung) for PFOA, and from 1.0 to 13.6 ng/g (respectively: skeletal muscle and liver) for the linear isomer of PFOS. The method is suitable to evaluate the content of PFOA and PFOS in different tissues taken from the general population exposed to very low concentrations of these pollutants. Copyright © 2006 John Wiley & Sons, Ltd.
Negative gas‐phase ion chemistry of silane: a quadrupole ion trap study
Authors: Operti Lorenza , Rabezzana Roberto , Vaglio Gian Angelo
Published: August 2006

Silicon clusters are of considerable interest for their importance in astrophysics and chemical vapour deposition processes, as well as from a fundamental point of view. Here, we present a quadrupole ion trap study of the self‐condensation ion/molecule reactions of anions of silane. In the high‐pressure regime, several ion clusters are formed with increasing size: the largest ions detected are Si5H (n = 0–3). Selective ion isolation and storage allowed detection of the main reaction sequences occurring in the reacting system. The most frequent condensation step is followed by single or multiple dehydrogenation, this latter being particularly observed for the high‐mass reactant ions. As a consequence, the most abundant ions in the mass spectra are those with a low content of hydrogen, namely Si2H−, Si3H−, and Si4H−. These results are discussed with reference to literature data on silicon cluster anions and related systems. Copyright © 2006 John Wiley & Sons, Ltd.
Perceived stress, psychological well‐being and the activity of neutrophils in patients undergoing cardiopulmonary bypass surgery
Authors: Ellard D.R. , Barlow J.H. , Mian R. , Patel R.
Published: August 2006

This study explored relationships, before and after surgery, between perceived stress and the activity of white‐blood cells (neutrophils) in 82 patients undergoing heart surgery involving cardiopulmonary bypass surgery (CPB).

On the evening before surgery and at follow‐up, 6‐weeks after discharge, patients completed self‐administered standard psychological measures. Small peripheral blood samples were taken, from which neutrophil activity was quantified using nitro‐blue tetrazolium (NBT) and luminol‐dependant chemiluminescence (phagocytic capacity).

There were consistent, statistically significant associations between stress and percentageNBT cells at baseline and at follow‐up. Regression analysis showed that perceived stress was a predictor of neutrophil activity at follow‐up suggesting that higher levels of stress are associated with higher levels of activity. Results from the phagocytic capacity data support and strengthen the NBT findings; in response to stimuli the phagocytic capacity of the neutrophils is reduced at baseline (high stress) and increased at follow‐up (lower stress). Significant decreases were found on perceived stress, anxiety, depression, negative affect and health‐related stress at follow‐up. Patients' self‐efficacy was high at baseline and remained high throughout the study.

Results highlighted a consistent, significant relationship between perceived stress and the ‘activity’ of neutrophils. The implications of this finding are worthy of exploration given that stress‐activated neutrophils may adversely influence health outcomes. Copyright © 2006 John Wiley & Sons, Ltd.
Self‐focused attention and self‐monitoring influence on health and coping with stress
Authors: Huflejt‐ukasik Mirosawa , Czarnota‐Bojarska Joanna
Published: August 2006

The issue of the presented study was to find relations between the elements of self‐focused attention, self‐monitoring and different styles of coping with stress and psychosomatic symptoms.

The two factors of self‐focused attention must be considered: (1) the private self‐consciousness, the tendency to be aware of those aspects of one's own self which cannot be observed by others; (2) the public self‐consciousness, the tendency to be aware of the publicly displayed aspects of the self.

The level of self‐monitoring determines the significance which a person attaches to indicators coming from his or her social surrounding while modifying and shaping his or her behaviour.

The results indicate both similarities and differences within the scope of both constructs: self‐monitoring and self‐focused attention. The differences between the constructs in question also pertain to their relation with psychopathology. Copyright © 2006 John Wiley & Sons, Ltd.
Work–family interference as a mediator between job demands and job burnout among doctors
Authors: Montgomery Anthony J. , Panagopolou Efharis , Benos Alexis
Published: August 2006

There is an increasing realization that the connections between work and family life are of critical importance in contemporary society. The present study examined the relationship between job demands and burnout, and the mediational role of work–family interference (WFI) in a sample of Greek doctors (N = 162). The main findings are: (1) emotional job demands were found to be a strong independent predictor of both emotional exhaustion and depersonalization; (2) quantitative job demands were found to predict emotional exhaustion; (3) WFI was found to partially mediate the relationship between both quantitative/emotional job demands and emotional exhaustion; (4) additionally, WFI partially mediated the relationship between emotional job demands and depersonalization. The results and limitations are discussed with reference to the medical profession. Copyright © 2006 John Wiley & Sons, Ltd.
Multistage growth and reworking of the Palaeoproterozoic crust in the Bergslagen area, southern Sweden: evidence from U–Pb geochronology
Authors: ANDERSSON ULF B. , HÖGDAHL KARIN , SJÖSTRÖM HÅKAN , BERGMAN STEFAN
Published: August 2006

The Svecofennian Domain of the Fennoscandian Shield constitutes a considerable volume of Palaeoproterozoic crustal growth, 2.1–1.86 Ga ago, in between the Archaean craton in the NE and the 1.85–1.65 Ga Transscandinavian Igneous Belt (TIB) in the south and west. The Bergslagen area is a classical ore province located in the southwestern part of the Svecofennian Domain of south-central Sweden. Its northern part is dominated by volcanic and plutonic rocks of a magmatic arc with continental affinity, while the SE part is made up by a sedimentary basin. The Bergslagen area shows a metamorphic zonation from lower to middle amphibolite facies in the north to upper amphibolite facies and locally granulite facies in the south; a small greenschist area exists in the west. Identifying the age spectra of inherited components, magmatic crystallization, as well as metamorphic episodes, provide important constraints on the geodynamic evolution of this centrally located piece of the Shield.

U–Pb zircon SIMS data presented in this paper complement the previous, regionally scattered TIMS data from this area. Magmatic zircons from two felsic metavolcanic rocks and two amphibolites (metagabbros) yield 1888±12, 1892±7 and 1887±5, 1895±5 Ma, respectively; i.e. within the 1.91–1.86 Ga range previously obtained for Early Svecofennian magmatism in Bergslagen. An augen gneiss from southern Bergslagen, assigned to the earliest TIB generation, yield an intrusive age of 1855±6 Ma. Metamorphic monazites from the same rock indicate that deformation and elevated thermal activity prevailed 1.83–1.82 Ga ago (TIMS). Metamorphic zircons in high-grade metasedimentary rocks from the south and west yield ages of 1793±5 and 1804±10 Ma, in accordance with ages for regional peak metamorphism and migmatite formation found elsewhere in the southern Svecofennian province of Sweden. More importantly, a few zircon crystals and overgrowths in rocks from the north indicate an early metamorphic episode at c. 1.87 Ga, indicating that Bergslagen has experienced two major metamorphic events. Detrital and inherited zircons span the range 2.78–1.90 Ga, with an apparent gap at 2.45–2.1 Ga, which further emphasize previous observations of a major juvenile (<2.1 Ga) and a minor Archaean provenance. This, and in particular the 1.94–1.91 Ga crystals present in the c. 1.89 Ga amphibolites, support the suggestion of a former Palaeoproterozoic pre-1.91 Ga crust in the Bergslagen area.
Idiopathic maxillary antral mucocele in a child: a rare presentation
Authors: Del Pero M Martinez , Sharma R K , Raghavan A , Bateman N
Published: August 2006

We report a case of a large maxillary sinus mucocele in a 14-year-old girl presenting with epiphora, proptosis and dental pain. This was marsupialized endoscopically, with complete resolution of symptoms over three months’ follow up. The literature is reviewed.
Vortex formation in a non-uniform self-gravitating dusty magnetoplasma
Authors: IJAZ AISHA , MIRZA ARSHAD M. , AZEEM M.
Published: August 2006

The dynamics of low-frequency, short-wavelength electrostatic (SWES) drift waves in a self-gravitating, non-uniform, collisional dusty magnetoplasma with equilibrium dust-velocity gradients is studied in the present work. By employing the dust continuity and momentum equations to describe the dust dynamics and Boltzmann distribution for the electrons and ions, we have derived a new set of nonlinear mode coupling equations. In the linear limit, it is found that SWES drift waves are subjected to dissipative instability in the presence of an equilibrium dust sheared flow and self-gravitation effect. On the other hand, in the nonlinear case, it is shown that possible stationary solutions of the nonlinear equations are dipolar vortices.
Covariant form for the collision integral
Authors: MELROSE D. B.
Published: August 2006

The collision integral that describes the evolution of a distribution of particles in a plasma due to Coulomb interactions between themselves or with other particles is generalized to include relativistic effects and the current–current interaction (in addition to the charge–charge interaction). This is achieved through a covariant version of a conventional derivation based on correlation functions for fluctuations in the plasma. The covariant theory is used to distinguish between longitudinal (charge–charge) and transverse (current–current) interactions. For highly relativistic particles, the current–current contribution is half the charge–charge contribution when Debye screening is unimportant, and is unaffected by Debye screening. It is shown that the classical theory is reproduced by a quantum electrodynamics calculation for electron–electron (Møller) scattering in the limit of small momentum transfer.
Tamao travel time of sudden impulses and its relationship to ionospheric convection vortices
Authors: Chi P. J. , Lee Dong‐Hun , Russell C. T.
Published: August 2006

We have examined the propagation of sudden impulses (SI) by an MHD numerical simulation in the three‐dimensional magnetosphere to assess the precision of the Tamao travel time approximation and the dynamic properties of preliminary impulses (PI). The results show that the propagation of SI signals is strongly influenced by the inhomogeneous Alfvén velocity profile, and the region of high Alfvén velocity immediately outside the plasmasphere allows the signals to reach ionospheric altitudes in the shortest time possible. At the ionospheric altitude, the simulated arrival time of the PI, defined by the first peak in wave amplitude, is in extremely good agreement with Tamao's prediction throughout the range of invariant latitudes connected to the outer magnetosphere. The arrival time at invariant latitudes within the plasmasphere, however, is slightly earlier than Tamao's prediction because of the fact that the impulse deviates from a point source as it arrives at the plasmapause. In contrast, the onset time of the PI, which corresponds to the first deflection in the magnetic field, varies little with invariant latitude, consistent with the well‐established observations of the nearly simultaneous PI onset without the need to invoke the Earth‐ionosphere waveguide model. Our simulation also shows that the differentiation in PI arrival time strongly influences the evolution of the ionospheric convection vortices. The twin vortices first appear slightly above the latitude connected to the plasmapause, and they move poleward because of the late arrival of impulse signals at higher latitudes. Another pair of vortices appears later at plasmaspheric latitudes owing to the delay of signals by the dense plasmasphere. Our results not only provide quantitative assessment on the Tamao path, which can benefit future development in travel time magnetoseismology, but they also demonstrate the evolution of PI‐induced ionospheric convection vortices by incorporating the propagation characteristics of MHD waves.
Fluid release from the subducted Cocos plate and partial melting of the crust deduced from magnetotelluric studies in southern Mexico: Implications for the generation of volcanism and subduction dynamics
Authors: Jödicke H. , Jording A. , Ferrari L. , Arzate J. , Mezger K. , Rüpke L.
Published: August 2006

In order to study electrical conductivity phenomena that are associated with subduction related fluid release and melt production, magnetotelluric (MT) measurements were carried out in southern Mexico along two coast to coast profiles. The conductivity‐depth distribution was obtained by simultaneous two‐dimensional inversion of the transverse magnetic and transverse electric modes of the magnetotelluric transfer functions. The MT models demonstrate that the plate southern profile shows enhanced conductivity in the deep crust. The northern profile is dominated by an elongated conductive zone extending >250 km below the Trans‐Mexican Volcanic Belt (TMVB). The isolated conductivity anomalies in the southern profile are interpreted as slab fluids stored in the overlying deep continental crust. These fluids were released by progressive metamorphic dehydration of the basaltic oceanic crust. The conductivity anomalies may be related to the main dehydration reactions at the zeolite → blueschist → eclogite facies transitions and the breakdown of chlorite. This relation allows the estimation of a geothermal gradient of ∼8.5°C/km for the top of the subducting plate. The same dehydration reactions may be recognized along the northern profile at the same position relative to the depth of the plate, but more inland due to a shallower dip, and merge near the volcanic front due to steep downbending of the plate. When the oceanic crust reaches a depth of 80–90 km, ascending fluids produce basaltic melts in the intervening hot subcontinental mantle wedge that give rise to the volcanic belt. Water‐rich basalts may intrude into the lower continental crust leading to partial melting. The elongated highly conductive zone below the TMVB may therefore be caused by partial melts and fluids of various origins, ongoing migmatization, ascending basaltic and granitic melts, growing plutons as well as residual metamorphic fluids. Zones of extremely high conductance (>8000 S) in the continental crust on either MT profile might indicate extinct magmatism.
Transmission to reflection transformation of teleseismic wavefields
Authors: Kumar M. Ravi , Bostock M. G.
Published: August 2006

In this paper we review the transformation of P and SV transmission Green's functions into the corresponding reflection quantities for one‐dimensional, elastic media at precritical slownesses. To obtain estimates of the transmission Green's functions from observed data, we apply a recently developed approach that exploits the minimum‐phase nature of the direct waves and employs autospectra and cross‐spectra of raw component seismograms representing multiple sources recorded at a single station. To accomplish transformation to reflection Green's functions, we outline a practical recipe that involves amplitude balancing, energy normalization, cross correlation, and removal of free surface effects. We assess its performance through application to both synthetic seismograms and data from station Hyderabad. In all cases we are able to identify the first‐order scattering contributions from the continental Moho. The transmission‐to‐reflection transformation has potential applications for imaging hitherto elusive shallow mantle discontinuities, since interfering forward and back scattering contributions are effectively separated by component in the resulting reflection Green's functions.
Investigation of upper mantle discontinuity structure beneath the central Pacific using SS precursors
Authors: Schmerr Nicholas , Garnero Edward
Published: August 2006

Using a high‐quality broadband seismic data set of precursors to the phase SS, we investigate the structure of upper mantle discontinuities beneath the central Pacific including the Hawaiian hot spot. We image structure by stacking over 4000 records into geographic bins, retaining periods down to 5 s. We consider the effects of correcting for four separate tomographic models of mantle heterogeneity, excluding data at distances containing phases that potentially interfere with precursors. We find evidence for peak‐to‐peak topography of 15–20 km on the 670‐km discontinuity and 7–28 km of topography on the 400‐km discontinuity. Weak reflections are detected from discontinuities near 220‐ and 520‐km depth. The average transition zone thickness beneath our region is approximately 242 ± 3 km, very similar to previous estimates of the global average. Lateral transition zone thinning and thickening weakly correlate with reduced and increased transition zone shear velocity, respectively, consistent with a thermal origin to topographical variations on the discontinuities within our study region. The transition zone beneath Hawaii and to the east of the Line Island Chain is thinned by up to 20 km in a province spanning nearly 1000 km, suggesting an excess mantle temperature of ∼200 K. In the oldest crustal regions of our study area (>100 Ma), the 400‐km discontinuity is relatively shallow, and the transition zone is relatively thick (250–255 km); a possible explanation for this pattern includes small‐scale convection in the upper mantle bringing colder material into the transition zone.
Forecasting total electron content maps by neural network technique
Authors: Tulunay Ersin , Senalp Erdem Turker , Radicella Sandro Maria , Tulunay Yurdanur
Published: August 2006

Near‐Earth space processes are highly nonlinear. Since the 1990s, a small group at the Middle East Technical University in Ankara has been working on a data‐driven generic model of such processes, that is, forecasting and nowcasting of a near‐Earth space parameter of interest. The model developed is called the Middle East Technical University Neural Network (METU‐NN) model. The METU‐NN is a data‐driven neural network model of one hidden layer and several neurons. In order to understand more about the complex response of the magnetosphere and ionosphere to extreme solar events, we chose this time the series of space weather events in November 2003. Total electron content (TEC) values of the ionosphere are forecast during these space weather events. In order to facilitate an easier interpretation of the forecast TEC values, maps of TEC are produced by using the Bezier surface‐fitting technique.
Scattering height estimation using scintillating Wide Area Augmentation System/Satellite Based Augmentation System and GPS satellite signals
Authors: Cerruti A. P. , Ledvina B. M. , Kintner P. M.
Published: August 2006

An experiment to measure equatorial amplitude scintillations on the geostationary Wide Area Augmentation System (WAAS) Satellite Based Augmentation System (SBAS) signal was conducted in Cachoeira Paulista (22.70°S, 45.01°W geographic coordinates; −17.74°N, 21.74°E geomagnetic coordinates), Brazil from December 2003 through February 2004. The purpose of this paper is to estimate the scattering height of the irregularities using the WAAS signal scintillations as compared to nearby Global Positioning System (GPS) signal scintillations. Estimating the scattering height is important because the calculated zonal drift velocity of the irregularities using the measured scintillation pattern velocity on the ground is height dependent. Accurate height estimation is also required if one wishes to develop phase screen scintillation models. The difference in the pattern velocities is due to the different signal puncture point velocities with respect to the ionospheric drift. Two east‐west receivers are used to measure the scintillation pattern drift velocity and to compare the results of the geostationary WAAS satellite signal to that of a GPS satellite signal, which has a nonzero ionospheric signal puncture point velocity. By varying the assumed scattering height for the measurements from the nearby GPS signal, the zonal velocity measurements from the GPS scintillations can be matched to those of the WAAS scintillations, and a scattering height estimate can be made. When the puncture points have minimal separation, the inferred ionospheric irregularity zonal velocities should be equal. On the two nights for which data are available, scattering height estimates of 669 ± 209 km for the first night and 388 ± 139 km for the second night were obtained. On the second night, the reported mean hmF2 as calculated using a collocated Digisonde was 385 ± 17 km over the same period as the GPS/WAAS scattering height estimate. The geometry of this experiment was not optimal, but analysis demonstrates that future experiments could be substantially more accurate.
Active faulting in the Birjand region of NE Iran
Authors: Walker R. T. , Khatib M. M.
Published: August 2006

We use satellite imagery and field observations to investigate the distribution of active faults around Birjand in eastern Iran to determine how the transition between conjugate zones of faulting can be accommodated by diffuse active faulting. In the south of the study area, right‐lateral strike‐slip faults of the Sistan Suture Zone end in thrusts which die away westward from the strike‐slip faults. These thrust terminations appear to allow a northward change to E‐W thrusting in central parts of the study area. The introduction of E‐W thrusting is, in turn, likely to facilitate a change to E‐W left‐lateral faulting north of the study region. The relatively diffuse pattern of active faulting at Birjand relates to the regional transition between N‐S and E‐W strike‐slip faulting in northeast Iran, which involves a change from nonrotational to rotational deformation. The change from N‐S to E‐W faulting is likely to result from the orientation of preexisting structures in Iran and western Afghanistan, which are roughly parallel to the active fault zones. The features described at Birjand also show the influence of preexisting structure on the location and style of active faulting at a local scale, with the position of individual faults apparently controlled by inherited geological weaknesses. Very few modern earthquakes have occurred in the region of Birjand and yet destructive events are known from the historical record. The large number of active faults mapped in this study pose a substantial seismic hazard to Birjand and surrounding regions.
Inhibition of L‐type calcium current by propafenone in single myocytes isolated from the rabbit atrioventricular node
Authors: Hancox Jules C , Mitcheson John S
Published: August 2006

The atrioventricular node (AVN) is an important part of the conduction system in the heart and is a significant site of antiarrhythmic drug action. The class 1 antiarrhythmic propafenone is effective in treating a variety of arrhythmias, including those involving the AVN. In this study, we have investigated the effects of propafenone on ionic currents in single rabbit AVN cells, focusing in particular on those on L‐type calcium current (ICa, L).

With a standard K‐based internal dialysis solution, exposure to 5 μM propafenone reduced significantly the amplitude of ICa, L. In spontaneously active AVN myocytes, action potential upstroke velocity was decreased by propafenone exposure, consistent with the observed change in ICa, L.

By use of a Cs‐based internal dialysis solution to record ICa, L selectively, voltage clamp test pulses were applied from a holding potential of −40 mV to +10 mV (stimulation frequency 0.33 Hz). Propafenone 5 μM reduced mean ICa, L density at +10 mV from −9.58±1.05 pA/pF to −4.19±0.60 pA/pF (P<0.002). A range of propafenone concentrations were applied which reduced ICa, L in a dose‐dependent manner (IC50 1.7 μM). When test pulses were applied to a range of potentials, propafenone reduced ICa, L at each potential without significantly affecting the activation curve for this current. Thus, propafenone reduced ICa, L conductance, without affecting the voltage‐dependent activation properties of the current.

ICa, L block by propafenone exhibited tonic‐, use‐ and frequency‐dependent characteristics.

In the presence of propafenone, the voltage‐dependence of inactivation of ICa, L was shifted 8 mV in the hyperpolarizing direction. Also, the recovery of ICa, L from inactivation was slowed by propafenone.

The ICa, L blocking properties of propafenone may mediate some of the antiarrhythmic properties of this agent, particularly in regions of the heart such as the AVN in which ICa, L contributes significantly to the action potential upstroke.

British Journal of Pharmacology (1997) 121, 7–14; doi:10.1038/sj.bjp.0701086
Peptidergic modulation of the sympathetic contraction in the rabbit ear artery: effects of temperature
Authors: Padilla J , García‐Villalón A L , Monge L , García J L , Fernández N , Gomez B , Dieguez G
Published: August 2006

The effects of neuropeptide Y, endothelin‐1, arginine‐vasopressin and angiotensin II on the vascular contraction to sympathetic nerve stimulation were studied in isolated segments, 2 mm long, from the rabbit central ear artery, a cutaneous vessel, during changes in temperature (24°–41°C).

Transmural electrical stimulation (1–8 Hz, at supramaximal voltage) produced frequency‐dependent contraction, and this response, partially blocked by tetrodotoxin (1 μM) and phentolamine (1 μM), was reduced by cooling (30°C–24°C) and was not modified by warming (41°C), as compared to that recorded at 37°C.

Pretreatment with neuropeptide Y (10, 30 and 100 nM) increased in a concentration‐dependent manner the vascular contraction to sympathetic stimulation at every temperature studied, but this potentiation was greater during cooling (34°C–24°C) than at 37°C or warming (41°C).

Pretreatment with endothelin‐1 (3 and 10 nM) or vasopressin (0.1, 0.3 and 1 nM) increased in a concentration‐dependent manner the vascular contraction to sympathetic stimulation during cooling (34°C–24°C), but not at 37°C or warming (41°C).

Pretreatment with angiotensin II (0.1, 0.3 and 1 μM) did not modify the contraction to sympathetic stimulation at any temperature studied.

These results suggest that neuropeptide Y, endothelin‐1 and vasopressin, but not angiotensin II, modulate the cutaneous vasoconstriction to sympathetic nerve stimulation by potentiating this vasoconstriction during cooling.

British Journal of Pharmacology (1997) 121, 21–28; doi:10.1038/sj.bjp.0701094