bluuebunny/crossref_metadata_2025 huggingface dataset:
The transparency of the Universe limited by Lyα clouds
Authors: Schild R. E. , Dekker M.
Published: July 2006

The brightnesses of supernovae are commonly understood to indicate that cosmological expansion is accelerating due to dark energy. However the entire discussion presumes a perfectly transparent universe because no effects of reddening associated with the interstellar extinction law are seen. We note that with two kinds of dark matter (baryonic and nonbaryonic) strongly dominating the known mass of the universe, it is seriously premature to assume that these dark matter components have not reduced the transmission of the universe for cosmological sources.

We show that the long‐known Lyα clouds, if nucleated by the population of baryonic dark matter primordial planetoids indicated by quasar microlensing, would act as spherical lenses and achromatically fade cosmologically distant sources. We attempt to estimate the amount of this cosmological fading, but ultimately the calculation is limited by lack of a satisfactory model for the tenuous outer parts of a primordial planetoid. We also consider the effects of such cosmological fading on the light of quasars. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A morphological analysis of NGC 7296
Authors: Tadross A. L.
Published: July 2006

A morphological analysis has been presented as a completed work for estimating the most physical properties of open star cluster NGC 7296. For this purpose, near‐IR database of the digital Two Micron All Sky Survey (2MASS) has been used. Center, radius, membership, distances, reddening, age, metallicity, luminosity and mass functions, total mass, mass segregation and the dynamical relaxation time of the cluster have been estimated. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Separation of dwarf and giant stars with ROTSE–IIId
Authors: Bilir S. , Güver T. , Aslan M.
Published: July 2006

136 stars which were known to be members of the open cluster NGC 752 were observed at the R band with the ROTSE–IIId telescope located at the Turkish National Observatory (TUG) site. The data had been evaluated together with BV and 2MASS photometric data. A new practical method for separating dwarf and giant was described and applied. Evaluating the colour magnitude–diagrams with Padova isochrones revealed for the open cluster NGC 752 a metallicity similar to the Sun and an age of 1.41 ± 0.20 Gyr. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Concerning the instantaneous mass and the extent of an expanding universe
Authors: Fahr H. J. , Heyl M.
Published: July 2006

In this article we want to answer the cosmologically relevant question what, with some good semantic and physical reason, could be called the massM u of an infinitely extended, homogeneously matter‐filled and expanding universe. To answer this question we produce a space‐like sum of instantaneous cosmic energy depositions surrounding equally each spacepoint in the homogeneous universe. We calculate the added‐up instantaneous cosmic energy per volume around an arbitrary space point in the expanding universe. To carry out this sum we use as basic metrics an analogy to the inner Schwarzschild metric applied to stars, but this time applied to the spacepoint‐related universe. It is then shown that this leads to the added‐up proper energy within a sphere of a finite outer critical radius defining the point‐related infinity. As a surprise this radius turns out to be reciprocal to the square root of the prevailing average cosmic energy density. The equivalent mass of the universe can then also be calculated and, by the expression which is obtained here, shows a scaling with this critical radius of this universe, a virtue of the universe which was already often called for in earlier works by E. Mach, H. Thirring and F. Hoyle and others. This radius on the other hand can be shown to be nearly equal to the Schwarzschild radius of the so‐defined mass M u of the universe. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The correlation between the local density of galaxies and the presence of Gamma‐Ray Bursts
Authors: Xin‐fa Deng , Yi‐qing Chen , Peng Jiang , Jun Song , Con‐gen He , Ji‐Zhoul He
Published: July 2006

In order to explore the characteristics of the environment surrounding Gamma‐Ray Bursts (GRBs), we have studied the correlation between the local density of galaxies and the presence of bursts. Using the Main Galaxy sample of the Sloan Digital Sky Survey Data Release 3 (SDSS DR3) and the Current BATSE GRB Catalog, we calculate the local surface density of galaxies within a radius of <2° surrounding each burst. It turns out that there is no correlation between the local density of galaxies and the presence of GRBs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light curve and period study of V Trianguli
Authors: Gürol B. , Müyesseroğlu Z. , Özdemir T.
Published: July 2006

New BVR light curves and times of minimum light for the short period β Lyrae system V Tri were analyzed to derive the physical parameters of the system. The light curves were obtained at Ankara University Observatory and at the TÜBİTAK National Observatory during 5 nights in 2001 and 2002. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson‐Devinney 2003 code. The present solution reveals that V Tri is a near‐contact system with a mass ratio near 0.5. The absolute radii and masses estimated for the components, based on our photometric solution, are R 1 = 1.94 R⊙, R 2 = 1.44 R⊙, M 1 = 2.68 M⊙, M 2 = 1.36 M⊙, respectively, for the primary and secondary components. The period variation of the system can be attributed to the light‐time effect. With the assumption of a coplanar orbit of the third body its revealed mass is m 3 = 0.17 M⊙. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Subclavian artery occlusion causing acute myocardial infarction in a patient with a left internal mammary artery graft
Authors: Barlis Peter , Brooks Mark , Hare David L. , Chan Robert K.
Published: July 2006

Although atherosclerotic disease of the subclavian artery has previously been reported to cause coronary–subclavian steal syndrome, acute myocardial infarction because of occlusion of the subclavian artery in a graft‐dependent coronary circulation is an uncommon and previously unreported mode of clinical presentation. Increasingly, patients undergoing high‐risk cardiopulmonary procedures have comorbidities with extensive atherosclerotic disease of many vascular beds including coronary, cranial, and peripheral. Our discussion reviews the clinical presentation of such a case and highlights some of the important treatment options available when confronted with such a finding. The successful outcome achieved by percutaneous stenting of the subclavian artery and salvage of the graft may indicate that this modality is the initial treatment of choice in such cases. © 2006 Wiley‐Liss, Inc.
Indicators of the maximum radiation dose to the skin during percutaneous coronary intervention in different target vessels
Authors: Chida Koichi , Saito Haruo , Kagaya Yutaka , Kohzuki Masahiro , Takai Yoshihiro , Takahashi Shoki , Yamada Shogo , Zuguchi Masayuki
Published: July 2006

Objectives: To evaluate whether the maximum radiation dose to the patient's skin (MSD) can be estimated during percutaneous coronary intervention (PCI) procedures, we investigated the relationship between the MSD and fluoroscopic time, dose‐area product (DAP), and body weight, separately analyzing the relationships for different target vessels. Background: Many cases of skin injury caused by excessive radiation exposure during cardiac intervention procedures have been reported. However, real‐time maximum‐dose monitoring of the skin is unavailable for many cardiac intervention procedures. Methods: We studied 197 consecutive PCI procedures that involved a single target vessel and were conducted. The DAP was measured, and the MSD was calculated by a skin‐dose mapping software program (Caregraph). The target vessels of the PCI procedures were divided into four groups based on the AHA classification system: AHA 5–10, left anterior descending artery domain (LAD), AHA 11–15, left circumflex artery domain (LCx), AHA 1–3 = R 1–3, and AHA 4 = R 4. Results: The correlation coefficient (r) between the MSD and fluoroscopic time was higher for the right coronary artery (RCA) vessels (R 1–3, 0.852; R 4, 0.715) than for the left coronary artery (LCA) vessels (LAD, 0.527; LCx, 0.646), and the r value between the MSD and DAP was higher for the RCA vessels (R 1–3, 0.871; R 4, 0.898) than for the LCA vessels (LAD, 0.628; LCx, 0.694). Similarly, the correlation coefficient between the MSD and weight × fluoroscopic time (WFP) was higher for the RCA vessels (R 1–3, 0.874; R 4, 0.807) than for the LCA vessels (LAD, 0.551; LCx, 0.735). Conclusions: The DAP and WFP can be used to estimate the MSD during PCI in the RCA but not in the LCA, especially the LAD. © 2006 Wiley‐Liss, Inc.
Quantitative microsatellite analysis to delineate the commonly deleted region 1p22.3 in mantle cell lymphomas
Authors: Balakrishnan Asha , von Neuhoff Nils , Rudolph Cornelia , Kamphues Kathrin , Schraders Margit , Groenen Patricia , van Krieken Johan HJM , Callet‐Bauchu Evelyne , Schlegelberger Brigitte , Steinemann Doris
Published: July 2006

The molecular pathogenesis of mantle cell lymphomas (MCL), a subset of B‐cell non‐Hodgkin's lymphomas with a poor prognosis, is still poorly understood. In addition to the characteristic primary genetic alteration t(11;14)(q13;q32), several further genetic changes are present in most cases. One of the most frequent genomic imbalances is the deletion of 1p22.1–p31.1 observed in nearly one‐third of MCL cases. This might indicate the presence of tumor suppressor gene(s) in this critical region of deletion. Quantitative microsatellite analysis (QuMA) is a real‐time PCR‐based method to detect DNA copy number changes. Since QuMA has the resolving power to detect subtle genomic alterations, including homozygous deletions, this may help to identify candidate tumor suppressor genes from deleted regions. To gain more insight into the molecular pathogenesis of MCL, QuMA was performed on genomic DNA from 57 MCL cases. Eight microsatellite loci mapping to the chromosomal region 1p22.3 were analyzed. Losses were observed in 51 of the 57 (∼89.5%) samples. Two cases showed a homozygous deletion at the locus containing the gene SH3GLB1, which plays a key role in Bax‐mediated apoptosis. Two hotspots with copy number losses were detected at chromosomal localizations 85.4 and 86.6 Mb encompassing BCL10 and CLCA2. Both the genes seem to be attractive candidates to study tumor suppressor function in MCL. This article contains Supplementary material available at http://www.interscience.wiley.com/jpages/1045–2257/suppmat. © 2006 Wiley‐Liss, Inc.
A sliding‐window weighted linkage disequilibrium test
Authors: Yang Hsin‐Chou , Lin Chin‐Yu , Fann Cathy S.J.
Published: July 2006

Multilocus linkage disequilibrium (LD) tests that consider inter‐marker (LD) are more powerful than single‐locus tests when disease etiology is contributed simultaneously by several linked and correlated loci. However, inclusion of redundant non‐informative markers may result in reduced testing power and/or inflated false‐positive rate, therefore selection of proper marker sets is important in such tests. We introduce a unified LD test based on a convenient marker‐selection procedure (sliding window) combined with an adjustment approach (marker weighting) to dilute the impact of nuisance markers on tests. The proposed procedure includes several conventional p‐value combination methods as its special cases. Simulation studies were performed to evaluate the impact of inclusion of nuisance markers and performance of the procedure. The results showed that testing power was often inversely proportional to the quantity of nuisance markers. Among a class of p‐value combination methods, the product p‐value method had the highest testing power. P‐value truncation somewhat reduced the testing power but controlled the false‐positive rate well. Compared with conventional unweighted approaches, the weighted strategy alleviated the false‐positive rate and/or increased testing power when nuisance markers were included. Analyses of two authentic data sets for psoriasis and Alzheimer's disease using our proposed method confirmed previous findings. Genet. Epidemiol. 2006. © 2006 Wiley‐Liss, Inc.
Immunohistochemical and histochemical findings favoring the occurrence of autocrine/paracrine as well as nerve‐related cholinergic effects in chronic painful patellar tendon tendinosis
Authors: Danielson Patrik , Alfredson Håkan , Forsgren Sture
Published: July 2006

The pathogenesis of the pain in patellar tendon tendinosis (“jumper's knee”) is unclear. We have recently presented new information about the sensory nervous system in the human patellar tendon, but there is very little information regarding the possible occurrence of a cholinergic system in this tendon. In the present study, specimens of pain‐free normal tendons and chronically painful tendinosis tendons were examined by different immunohistochemical and histochemical methods. Antibodies against the M2receptor, choline acetyltransferase (ChAT), and vesicular acetylcholine transporter (VAChT) were applied, and staining for demonstration of activity of acetylcholinesterase (AChE) was also utilized. It was found that immunoreactions for the M2receptor could be detected intracellularly in both blood vessel cells and tenocytes, especially in tendinosis specimens. Furthermore, in the tendinosis specimens, some tenocytes were seen to exhibit immunoreaction for ChAT and VAChT. AChE reactions were seen in fine nerve fibers associated with small blood vessels in both the normal control tendons and the tendinosis tendons. The observations suggest that there is both a nerve related and a local cholinergic system in the human patellar tendon. As ChAT and VAChT immunoreactions were detected in tenocytes of tendinosis tendons, these cells might be a source of local acetylcholine (Ach) production. As both tenocytes and blood vessel cells were found to exhibit immunoreactions for the M2receptor, it is likely that both of these tissue cells may be influenced by ACh. Thus, in conclusion, there appears to be an upregulation of the cholinergic system, and an occurrence of autocrine/paracrine effects in this system, in the tendinosis patellar tendon. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Should ovarian cryopreservation be offered to girls with cancer
Authors: Weintraub Michael , Gross Eitan , Kadari Avishag , Ravitsky Vardit , Safran Anat , Laufer Neri , Revel Ariel
Published: July 2006

Current therapy of childhood cancer makes long‐term survival a realistic outcome for most patients. However, some treatment regimens entail a significant risk of infertility. No established method for preservation of female fertility is currently available. Ovarian cryopreservation is an experimental technology that is being offered with increasing frequency to women undergoing cancer therapy. It has not yet been reported in children and adolescent girls. The aim of this review is to stimulate discussion on the possibility of performing ovarian cryopreservation in pre‐menarcheal girls in advance of therapies that may induce ovarian failure. We present a multi‐disciplinary discussion of the risks and benefits associated with the procedure and propose guidelines for its implementation. We propose that all girls about to receive treatment that has a high risk for infertility be offered consultation about the possibility of ovarian cryopreservation. Pediatr Blood Cancer 2007;48:4–9. © 2006 Wiley‐Liss, Inc.
Self‐adaptive routing protocols for integrating cellular networks, WLANs, and MANETs
Authors: Cavalcanti Dave , Cordeiro Carlos , Kumar Anup , Agrawal Dharma P.
Published: July 2006

A growing need to have ubiquitous connectivity has motivated our research to provide continuous connection between various wireless platforms such as cellular networks, wireless local area networks (WLANs), and mobile ad hoc networks (MANETs). In this paper, we consider integration at the routing layer and propose two adaptable routing protocols (IRP‐RD and IRP‐PD) that exploit topology information stored at the fixed network components (cellular base stations and WLAN access points) for the route discovery and maintenance processes. Our proposed protocols can provide connectivity to the cellular network and/or WLAN hotspots through multihop routing, while differ in the gateway discovery approach used. In IRP‐RD, multihop routes to gateways to the cellular network or WLAN hot spots are discovered on demand, while in IRP‐PD out of coverage users proactively maintain routes to the gateways. Furthermore, proposed protocols can be used in any heterogeneous scenario, combining a cellular network and WLANs operating in infrastructure or ad hoc (MANET) mode. We provide simulation results that demonstrate the effectiveness of the proposed integrated routing protocols and show the advantages and drawbacks of each gateway discovery approach in different heterogeneous scenarios. Copyright © 2006 John Wiley & Sons, Ltd.
Differential atrial versus ventricular ANKRD1 gene expression is oppositely regulated at diastolic heart failure
Authors: Torrado Mario , Nespereira Beatriz , Bouzamayor Yolanda , Centeno Alberto , López Eduardo , Mikhailov Alexander T.
Published: July 2006

Diastolic heart failure (DHF) was produced in 6‐day‐old piglets by intravenous administration of Doxorubicin, and ANKRD1 protein and mRNA levels were determined in atrial (A) and ventricular (V) chambers of failing vs control hearts. In controls, ANKRD1 showed a left–right (L–R) asymmetric distribution with protein levels 2‐fold higher in the LA as compared to the RA, and 8‐fold higher in the LV than the RV. In failing hearts, ANKRD1 levels were augmented about 2‐fold in each ventricle but equally reduced in both atria as compared to controls. ANKRD1 downregulation in atria is discussed as a process associated with advanced DHF.
Identification of residues crucially involved in soluble guanylate cyclase activation
Authors: Rothkegel Christiane , Schmidt Peter M. , Stoll Friederike , Schröder Henning , Schmidt Harald H.H.W. , Stasch Johannes-Peter
Published: July 2006

The ubiquitous heterodimeric nitric oxide (NO) receptor soluble guanylate cyclase (sGC) plays a key role in various signal transduction pathways. Binding of NO takes place at the prosthetic heme moiety at the N‐terminus of the β1‐subunit of sGC. The induced structural changes lead to an activation of the catalytic C‐terminal domain of the enzyme and to an increased conversion of GTP into the second messenger cyclic GMP (cGMP). In the present work we selected and substituted different residues of the sGC heme‐binding pocket based on a sGC homology model. The generated sGC variants were tested in a cGMP reporter cell for their effect on the enzyme activation by heme‐dependent (NO, BAY 41‐2272) stimulators and heme‐independent (BAY 58‐2667) activators. The use of these experimental tools allows the enzyme's heme content to be explored in a non‐invasive manner. Asp44, Asp45 and Phe74 of the β1‐subunit were identified as being crucially important for functional enzyme activation. β1Asp45 may serve as a switch between different conformational states of sGC and point to a possible mechanism of action of the heme dependent sGC stimulator BAY 41‐2272. Furthermore, our data shows that the activation profile of β1IIe145 Tyr is unchanged compared to the native enzyme, suggesting that Tyr145 does not confer the ability to distinguish between NO and O2. In summary, the present work further elucidated intramolecular mechanisms underlying the NO‐ and BAY 41‐2272‐mediated sGC activation and raises questions regarding the postulated role of Tyr145 for ligand discrimination.
The cartilage specific microRNA‐140 targets histone deacetylase 4 in mouse cells
Authors: Tuddenham Lee , Wheeler Guy , Ntounia-Fousara Sofia , Waters Jasmine , Hajihosseini Mohammad K. , Clark Ian , Dalmay Tamas
Published: July 2006

MicroRNAs (miRNA) are short RNA molecules regulating the expression of specific mRNAs. We investigated the expression pattern and potential targets of mouse miR‐140 and found that miR‐140 is specifically expressed in cartilage tissues of mouse embryos during both long and flat bone development. MiR‐140 expression was detected in the limbs of E11.5 embryos in the primorida of future bones both in the fore and hindlimb and across autopod, zeugopod and stylopod. All digits of E14.5 fore‐ and hindlimbs showed accumulation of miR‐140, except the first digit of the hindlimb. MiR‐140 expression was also detected in the cartilagenous base of E17.5 skulls and in the sternum, the proximal rib heads and the developing vertebral column of E15.5 embryos. A potential target of miR‐140, histone deacetylase 4, was validated experimentally and the possible role of miR‐140 in long bone development is discussed.
Negative feedback predominates over cross‐regulation to control ERK MAPK activity in response to FGF signalling in embryos
Authors: Smith Terence Gordon , Karlsson Maria , Lunn J. Simon , Eblaghie Maxwell C. , Keenan Iain D. , Farrell Elizabeth R. , Tickle Cheryll , Storey Kate G. , Keyse Stephen M.
Published: July 2006

Expression of the gene encoding the MKP‐3/Pyst1 protein phosphatase, which inactivates ERK MAPK, is induced by FGF. However, which intracellular signalling pathway mediates this expression is unclear, with essential roles proposed for both ERK and PI(3)K in chick embryonic limb. Here, we report that MKP‐3/Pyst1 expression is sensitive to inhibition of ERK or MAPKK, that endogenous MKP‐3/Pyst1 co‐localizes with activated ERK, and expression of MKP‐3/Pyst1 in mice lacking PDK1, an essential mediator of PI(3)K signalling. We conclude that MKP‐3/Pyst1 expression is mediated by ERK activation and that negative feedback control predominates in limiting the extent of FGF‐induced ERK activity.
Closed Rupture of Both Flexor Tendons in the Same Digit
Authors: LANZETTA M. , CONOLLY W. B.
Published: July 2006

Closed ruptures of both normal flexor tendons in the same finger are extremely rare, only nine cases having been reported in the literature. We describe the case of a patient who sustained a closed rupture of both flexor digitorum profundus and flexor digitorum superficialis of the ring finger, following a forced hyperextension injury. The patient was treated by a two stage reconstruction of the flexor digitorum profundus. He regained full flexion and extension of the finger.
A survey of Knowledge Discovery and Data Mining process models
Authors: KURGAN LUKASZ A. , MUSILEK PETR
Published: July 2006

Knowledge Discovery and Data Mining is a very dynamic research and development area that is reaching maturity. As such, it requires stable and well-defined foundations, which are well understood and popularized throughout the community. This survey presents a historical overview, description and future directions concerning a standard for a Knowledge Discovery and Data Mining process model. It presents a motivation for use and a comprehensive comparison of several leading process models, and discusses their applications to both academic and industrial problems. The main goal of this review is the consolidation of the research in this area. The survey also proposes to enhance existing models by embedding other current standards to enable automation and interoperability of the entire process.
The influence of sampling intensity on vegetation classification and the implications for environmental management
Authors: COOPER A. , MCCANN T. , BUNCE R. G. H.
Published: July 2006

As part of a programme of landscape-scale habitat surveillance in the United Kingdom (UK), the effect of grassland sampling intensity on the outcome of numerical classification was assessed. Sample quadrats from two regions of the UK were available for post priori analysis; a random sample from Great Britain (GB), with grasslands sampled in proportion to area, and an independent stratified random sample from Northern Ireland (NI), with similar numbers of quadrats from agricultural and semi-natural grassland habitat strata. Classification of a combined area-proportional (balanced) random sample from GB and NI showed the species composition of UK grasslands to be determined largely by climate, landscape structure and land-use intensity. The classification was influenced primarily by the greater number of eutrophic agricultural grassland quadrats and semi-natural grassland quadrats of the larger GB study area. The semi-natural grasslands of NI, represented by a small number of quadrats, had little influence. Classification of a stratified NI sample combined with an area-proportional GB sample was influenced most by the NI semi-natural grassland quadrats. The structure of the classifications depended on sampling intensity. Vegetation classification should be derived from a balanced sample so that it is representative and its application does not lead to decisions being directed at classes of vegetation (or estimates derived from them) that are weighted by sampling intensity. Area-proportional sample design linked explicitly to landscape structure satisfies the requirement for a balanced classification. The issue of data-balance is relevant in conservation management and environmental assessment, where stratification is a commonly accepted procedure to reduce sampling effort, or is carried out to sample rare or ecologically interesting vegetation. It applies to landscape-scale vegetation classifications used for environmental assessments and to classifications that compare plant communities between regions (as in phytosociological studies). The issue is also important when combining environmental databases from international sources for classification purposes.
Short-term mangrove browsing by feral water buffalo: conflict between natural resources, wildlife and subsistence interests?
Authors: DAHDOUH-GUEBAS F. , VRANCKEN D. , RAVISHANKAR T. , KOEDAM N.
Published: July 2006

Management of the natural environment and its resources leads to conflicts between different stake-holders worldwide. Recently mangrove browsing by feral water buffalo in the East-Godavari Delta (India) has been considered a threat to the regeneration of mangroves by the local Forest Department, which led to conflicts between the authorities and local herds-men who have an ancient tradition involving feral water buffalo. The impact of browsing and grazing of mangroves by feral water buffalo was monitored. Feral water buffalo consumed mangroves, but not to the extent claimed by the Forest Department, prefering Avicennia alba, A. marina and A. officinalis. Their browsing behaviour was not linked to a height zone, and buffalo preferred the fresh leaves from previously undamaged branches. Under experimental and natural conditions, browsing induced compensatory regrowth in Avicennia. The carrying capacity of the mangrove appears to be sufficient to accumulate impact. There are both positive and negative impacts of livestock animals on forest ecosystems, and sociocultural consequences must be carefully assessed prior to enforcing a change in natural resource or environmental management. Before banning feral water buffalo from the mangrove, forest managers should confront their prejudices about the real impact of feral herbivores on these forests.
Monitoring the auroral electrojet from polar cap stations
Authors: Lyatsky W. , Tan Arjun , Lyatskaya Sonya
Published: July 2006

A method for monitoring the auroral electrojet from measurements at polar cap stations was developed. Since in the polar cap the auroral electrojet produces the magnetic field in both horizontal and vertical components, the method is accounting for all three components of the magnetic field. We studied statistically the correlation between hourly mean values of auroral electrojet AL index and magnetic disturbances at polar cap boundary for each magnetic field component and found that the best correlation takes place for total magnetic field disturbance T. Then we calculated mean values of the total magnetic field disturbances for each UT hour at four stations distributed along the polar cap boundary. The obtained values we called the T index of geomagnetic activity. We found high correlation between hourly mean values of the T index and the auroral electrojet AL/AE indices (correlation coefficients are ∼0.9) for any time when at least one of the stations was located at the nightside. This index also shows good correlation with solar wind parameters. We suggest that the T index might be an important independent measure for deriving the auroral electrojet, which might be useful in the cases when ground‐based measurements in the auroral zone are impossible as it takes place in the Southern Hemisphere. Since the T index is derived from an independent magnetometer network, it might also give important additional information on geomagnetic activity in both hemispheres.
Oxygen production and carbon sequestration in an upwelling coastal margin
Authors: Hales Burke , Karp‐Boss Lee , Perlin Alexander , Wheeler Patricia A.
Published: July 2006

We examined high‐resolution cross‐shelf distributions of particulate organic carbon (POC) and dissolved O2 during the upwelling season off the Oregon coast. Oxygen concentrations were supersaturated in surface waters, and hypoxic in near‐bottom waters, with greatly expanded hypoxic conditions late in the season. Simplified time‐dependent mass balances on cross‐shelf integrated concentrations of these two parameters, found the following: (1) The average net rate of photosynthesis generated 2.1 mmol O2 m−3 d−1 and (2) essentially none of the corresponding net carbon fixation of 1.4 mmol m−3 d−1 could be accounted for in the observed standing stocks of POC. After examining other possible sinks for carbon, we conclude that most of the net production is being exported to the adjacent deep ocean. A simplified POC budget suggests that about a quarter of the export is via alongshore advection, and the remainder is due to some other process. We propose a simplistic conceptual model of across‐shelf transport in which POC sinks to the bottom boundary layer where it comes into contact with mineral ballast material but is kept in suspension by high turbulence. When upwelling conditions ease, the BBL waters move seaward, carrying the suspended, ballasted POC with it where it sinks rapidly into the deep ocean at the shelf break. This suggests a mechanism whereby the duration and frequency of upwelling events and relaxations can determine the extent to which new carbon produced by photosynthesis in the coastal ocean is exported to depth rather than being respired on the shelf.
On the chaotic nature of solar‐terrestrial environment: Interplanetary Alfvén intermittency
Authors: Chian A. C.‐L. , Kamide Y. , Rempel E. L. , Santana W. M.
Published: July 2006

We present an overview of observational and theoretical evidence of chaos and intermittency in the solar‐terrestrial environment including solar dynamo, solar atmosphere, solar wind, and terrestrial magnetosphere‐ionosphere‐atmosphere. The chaotic nature of space plasmas is studied by a nonlinear model of Alfvén waves described by the low‐dimensional limit of the derivative nonlinear Schrödinger equation given by its stationary solutions in the frame moving with the driver wave velocity. A periodic window of the bifurcation diagram is constructed to identify two types of Alfvén chaos related to type‐I intermittency and crisis‐induced intermittency. We show that an Alfvén chaotic attractor is composed of chaotic saddles and unstable periodic orbits and explain the links between these unstable structures and Alfvén intermittency. The role of interplanetary Alfvén intermittency in the solar wind driving of intense geomagnetic activities is discussed.
A three‐dimensional MHD solar wind model with pickup protons
Authors: Usmanov A. V. , Goldstein M. L.
Published: July 2006

We have developed a three‐dimensional (3‐D) steady‐state MHD model of the solar corona and solar wind that covers the region from the coronal base to 100 AU and that accounts for the effects of pickup protons in the distant heliosphere. The model expands the two‐region model of Usmanov and Goldstein (2003) to include a region III that extends from 1–100 AU and incorporates a population of interstellar neutral hydrogen and its interaction with solar wind protons. Following the approach of Isenberg (1986) and Whang (1998), we consider the solar wind outside 1 AU as a combination of three comoving species, solar wind protons, electrons, and pickup protons, and solve the 3‐D steady‐state MHD equations with source terms due to photoionization and charge exchange. Separate energy equations are included for solar wind and pickup protons. We show that the pickup protons cause a deceleration of the solar wind and an increase in average plasma temperature with heliocentric distance beyond ∼10 AU. We compute the global structure of the solar wind from the coronal base to 100 AU and compare our results with Voyager 1 and 2 observations.
Leader/return‐stroke‐like processes in the initial stage of rocket‐triggered lightning
Authors: Olsen R. C. , Rakov V. A. , Jordan D. M. , Jerauld J. , Uman M. A. , Rambo K. J.
Published: July 2006

Linear streak film, video, current, and electric field records from nine triggered‐lightning flashes are analyzed to examine the process of cutoff and reestablishment of current during the initial stage of rocket‐triggered lightning. All of the data were acquired at the International Center for Lightning Research and Testing at Camp Blanding, Florida, in 2002 and 2003. It is shown that in some rocket‐triggered lightning events, the process of current cutoff and reestablishment during the initial stage is similar to a leader/return‐stroke sequence, although the currents in this process are typically an order of magnitude smaller (1 kA or so) than those in a triggered or natural lightning subsequent stroke (10–15 kA). The events were separated into two groups based on observed characteristics, with the duration of the current cutoff interval being the primary differentiating characteristic. In some cases, two or three failed attempts at current reestablishment prior to the successful resumption of current flow in the channel were observed. Currents associated with the unsuccessful attempts were typically an order of magnitude smaller (100 A or so) than in the process which finally reestablished the current.
Calibration of Special Sensor Microwave Imager/Sounder (SSMIS) upper air brightness temperature measurements using a comprehensive radiative transfer model
Authors: Kerola Dana Xavier
Published: July 2006

For purposes of completing the initial calibration and validation work for the Special Sensor Microwave Imager/Sounder (SSMIS) serial number 2 instrument, we have implemented a comprehensive radiative transfer model (RTM) in order to verify on‐orbit upper air brightness temperature measurements for SSMIS channels 19–24. Rigorous computational treatment of the effects of the Earth's magnetic field on absorption by oxygen in the stratosphere and mesosphere provides us a solid baseline for comparison of theoretically based forward RTM calculations with the satellite observations. With the inclusion of flexibility in our model to account for departures from perfect instrument behavior, initial results provide us a reasonable measure of confidence that the agreement of our model with the observations should make the SSMIS‐derived data products sufficiently reliable.
Satellite and surface observations of Nauru Island clouds: Differences between El Nino and La Nina periods
Authors: Porch William M. , Olsen Seth C. , Chylek Petr , Dubey Manvendra K. , Henderson Bradley G. , Clodius William
Published: July 2006

Island cloud trails represent only a small fraction of ocean boundary layer clouds. However, they can be an important key to understanding how marine boundary layer clouds respond to perturbation. During the La Niña period of 1999–2001 the island cloud of Nauru demonstrated daytime persistence over 100 kilometers. Our results show that boundary layer clouds over the eastern margin of the warm pool are affected by regional subsidence and lack of CCN (Cloud Condensation Nuclei) during this active warm pool convection phase of the ENSO (El Nino Southern Oscillation). The increased persistence of boundary layer clouds during the day, as reflected by the island cloud trails, combined with the dissipation of boundary layer clouds at night contribute to cooling the ocean surface. During La Nina, boundary layer cloudiness around Nauru decreased by a factor of 1.9 and SSTs decreased by about 3°C.
Deterministic prediction of post‐sunset ESF based on the strength and asymmetry of EIA from ground based TEC measurements: Preliminary results
Authors: Thampi Smitha V. , Ravindran Sudha , Pant Tarun Kumar , Devasia C. V. , Sreelatha P. , Sridharan R.
Published: July 2006

This paper provides the first observations of EIA asymmetry by receiving beacon transmissions onboard low earth orbiting satellites from a single station ground‐based receiver. The EIA strength and asymmetry are derived from the latitudinal profiles of TEC obtained from a radio beacon receiver at Trivandrum (8.5°N, 77°E, diplat ∼0.5°N). These two parameters, obtained well ahead of the onset time of ESF, are shown to have a definite role on the subsequent ESF activity. In the present paper, both these factors are combined to define a new ‘threshold parameter’ for the generation of ESF. It has been shown that this parameter can define the state of the ‘background ionosphere’ conducive for the generation of ESF irregularities much prior to its onset.
Testing Brutsaert's temperature roughness parameterization for representing urban surfaces in atmospheric models
Authors: De Ridder Koen
Published: July 2006

It is verified whether Brutsaert's temperature roughness parameterization, developed for surfaces composed of solid obstacles arrays, is suitable for representing urban surfaces in high‐resolution atmospheric models. In order to do so, the temperature roughness parameterization is incorporated into a land surface scheme coupled to a mesoscale meteorological model, and the latter is subsequently used to perform a simulation over the larger area of Paris on a cloud‐free day. As a main result, it is found that simulated land surface temperature compares favourably to observed values obtained from thermal infrared satellite imagery. This confirms the validity of Brutsaert's thermal roughness parameterization, thus warranting its use in regional‐scale prognostic atmospheric models employed for, e.g., weather forecasting or air pollution studies.
The replication kinase Cdc7‐Dbf4 promotes the interaction of the p150 subunit of chromatin assembly factor 1 with proliferating cell nuclear antigen
Authors: Gérard Annabelle , Koundrioukoff Stéphane , Ramillon Vincent , Sergère Jean‐Christophe , Mailand Niels , Quivy Jean‐Pierre , Almouzni Geneviève
Published: July 2006

The coordination of chromatin assembly with DNA replication, which is essential for genomic stability, requires the combined activation of histone deposition with the firing of replication origins. We report here the direct interaction of chromatin assembly factor 1 (CAF1), a key factor involved in histone deposition, with the replication kinase Cdc7‐Dbf4. We isolated a complex containing both the largest subunit of CAF1 (p150) and the Cdc7‐Dbf4 kinase specifically in S phase and thus prove the existence of this interaction in vivo. We then show that the Cdc7‐Dbf4 kinase efficiently phosphorylates p150. This event induces a change in p150 oligomerization state, which promotes binding to proliferating cell nuclear antigen (PCNA). Conversely, CAF1 recruitment is reduced in a PCNA/DNA loading assay using Cdc7‐depleted extracts. Our data define p150 as a new target for this kinase with implications for the coordination between DNA replication and CAF1 functions.
Structural mimicry for vinculin activation by IpaA, a virulence factor of Shigella flexneri
Authors: Hamiaux Cyril , van Eerde André , Parsot Claude , Broos Jaap , Dijkstra Bauke W
Published: July 2006

Invasion of epithelial cells by Shigella flexneri is characterized by cytoskeletal rearrangements of the host cell membrane, promoting internalization of the bacterium. The bacterial effector IpaA is injected into the epithelial cell by a type III secretion apparatus and recruits vinculin to regulate actin polymerization at the site of entry. We analysed the complex formed between a carboxy‐terminal fragment of IpaA (IpaA560−633) and the vinculin D1 domain (VD1), both in crystals and in solution. We present evidence that IpaA560−633 has two α‐helical vinculin‐binding sites that simultaneously bind two VD1 molecules. The interaction of IpaA560−633 with VD1 is highly similar to the interaction of the endogenous, eukaryotic proteins talin and α‐actinin with VD1, showing that Shigella uses a structural mimicry strategy to activate vinculin.
Neuroprotective Effect of Exogenous Microglia in Global Brain Ischemia
Authors: Imai Fumihiro , Suzuki Hiromi , Oda Jumpei , Ninomiya Takashi , Ono Kenji , Sano Hirotoshi , Sawada Makoto
Published: July 2006

Exogenous microglia pass through the blood—brain barrier and migrate to ischemic hippocampal lesions when injected into the circulation. We investigated the effect of exogenous microglia on ischemic CA1 pyramidal neurons. Microglia were isolated from neonatal mixed brain cultures, labeled with the fluorescent dye PKH26, and injected into the subclavian artery of Mongolian gerbils subjected to ischemia reperfusion neuronal injury. PKH26-labeled microglia migrated to the ischemic hippocampal lesion, resulting in increased numbers of surviving neurons compared with control animals, even when injected 24 h after ischemia. Interferon-γ stimulation of isolated microglia enhanced the neuroprotective effect. Administration of exogenous microglia resulted in normal performance in a passive avoidance-learning task. Additionally, administration of exogenous microglia increased the expression of brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor in the ischemic hippocampus, and thus might have induced neurotrophin-dependent protective activity in damaged neurons. Peripherally injected microglia exhibited a specific affinity for ischemic brain lesions, and protected against ischemic neuronal injury in vivo. It is possible that administration of exogenous microglia can be developed as a potential candidate therapy for central nervous system repair after transitory global ischemia.
Bad as a Converging Signaling Molecule between Survival PI3-K/Akt and Death JNK in Neurons after Transient Focal Cerebral Ischemia in Rats
Authors: Kamada Hiroshi , Nito Chikako , Endo Hidenori , Chan Pak H
Published: July 2006

Bad, a proapoptotic Bcl-2 family protein, plays a critical role in determining cell death/survival. The phosphatidylinositol 3-kinase (PI3-K)/Akt pathway and the c-Jun N-terminal kinase (JNK) pathway are thought to be involved in regulation of Bad. Therefore, the present study was performed to clarify the role of Bad as a common target of the PI3-K/Akt and JNK pathways after transient focal cerebral ischemia (tFCI) in rats. We found that Akt activity increased at 3 h and then decreased, whereas JNK activity increased 7 to 24 h in the peripheral area after tFCI. Administration of LY294002, a PI3-K-specific inhibitor, exacerbated DNA fragmentation, whereas administration of SP600125, a JNK-specific inhibitor, attenuated it. Inhibited by LY294002, phospho-Bad (Ser136) expression increased in the peripheral area 3 h after tFCI, with suppression of Akt activity. Furthermore, phospho-Bad (Ser136) and phospho-Akt (Ser473) were colocalized. Decreases in phospho-Bad (Ser136) and Bad/14-3-3 dimerization and increases in Bcl-XL/Bad or Bcl-2/Bad dimerization observed 7 to 24 h after tFCI, were prevented by SP600125 administration, with inhibition of JNK activity. The present study indicates that signal predominance varies from PI3-K/Akt-mediated survival signaling to JNK-mediated death signaling with the development of neuronal damage in the peripheral area after tFCI. This study also suggests that PI3-K/Akt has a role in Bad inactivation, whereas the JNK pathway is involved in Bad activation. We conclude that Bad may be an integrated checkpoint of PI3-K/Akt-mediated survival signaling and JNK-mediated death signaling and that it contributes to cell fate in the peripheral area after cerebral ischemia.
Neuronal nitric oxide synthase-induced S-nitrosylation of H-Ras inhibits calcium ionophore-mediated extracellular-signal-regulated kinase activity
Authors: Raines Kimberly W. , Cao Guan-Liang , Lee Eun Kyoung , Rosen Gerald M. , Shapiro Paul
Published: July 2006

nNOS (neuronal nitric oxide synthase) is a constitutively expressed enzyme responsible for the production of NO• from L-arginine and O2. NO• acts as both an intra- and an inter-cellular messenger that mediates a variety of signalling pathways. Previous studies from our laboratory have demonstrated that nNOS production of NO• blocks Ca2+-ionophore-induced activation of ERK1/2 (extracellular-signal-regulated kinase 1/2) of the mitogen-activated protein kinases through a mechanism involving Ras G-proteins and Raf-1 kinase. Herein we describe a mechanism by which NO• blocks Ca2+-mediated ERK1/2 activity through direct modification of H-Ras. Ca2+-mediated ERK1/2 activation in NO•-producing cells could be restored by exogenous expression of constitutively active mitogen-activated protein kinase kinase 1. In contrast, exogenous expression of constitutively active mutants of Raf-1 and H-Ras only partially restored ERK1/2 activity, by 50% and 10% respectively. On the basis of these findings, we focused on NO•-mediated mechanisms of H-Ras inhibition. Assays for GTP loading and H-Ras interactions with the Ras-binding domain on Raf-1 demonstrated a decrease in H-Ras activity in the presence of NO•. We demonstrate that S-nitrosylation of H-Ras occurs in nNOS-expressing cells activated with Ca2+ ionophore. Mutation of a putative nitrosylation site at Cys118 inhibited S-nitrosylation and restored ERK1/2 activity by constitutively active H-Ras even in the presence of NO•. These findings indicate that intracellular generation of NO• by nNOS leads to S-nitrosylation of H-Ras, which interferes with Raf-1 activation and propagation of signalling through ERK1/2.
Evidence for allosteric regulation of pH-sensitive System A (SNAT2) and System N (SNAT5) amino acid transporter activity involving a conserved histidine residue
Authors: Baird Fiona E. , Pinilla-Tenas Jorge J. , Ogilvie William L. J. , Ganapathy Vadival , Hundal Harinder S. , Taylor Peter M.
Published: July 2006

System A and N amino acid transporters are key effectors of movement of amino acids across the plasma membrane of mammalian cells. These Na+-dependent transporters of the SLC38 gene family are highly sensitive to changes in pH within the physiological range, with transport markedly depressed at pH 7.0. We have investigated the possible role of histidine residues in the transporter proteins in determining this pH-sensitivity. The histidine-modifying agent DEPC (diethyl pyrocarbonate) markedly reduces the pH-sensitivity of SNAT2 and SNAT5 transporters (representative isoforms of System A and N respectively, overexpressed in Xenopus oocytes) in a concentration-dependent manner but does not completely inactivate transport activity. These effects of DEPC were reversed by hydroxylamine and partially blocked in the presence of excess amino acid substrate. DEPC treatment also blocked a reduction in apparent affinity for Na+ (K0.5Na+) of the SNAT2 transporter at low external pH. Mutation of the highly conserved C-terminal histidine residue to alanine in either SNAT2 (H504A) or SNAT5 (H471A) produced a transport phenotype exhibiting reduced, DEPC-resistant pH-sensitivity with no change in K0.5Na+ at low external pH. We suggest that the pH-sensitivity of these structurally related transporters results at least partly from a common allosteric mechanism influencing Na+ binding, which involves an H+-modifier site associated with C-terminal histidine residues.