bluuebunny/crossref_metadata_2025 huggingface dataset:
Woodpecker Densities in the Big Woods of Arkansas
Authors: Krementz David G. , Luscier Jason D.
Published: June 2010

Sightings of the now-feared-extinct ivory-billed woodpecker Campephilus principalis in 2004 in the Big Woods of Arkansas initiated a series of studies on how to best manage habitat for this endangered species as well as all woodpeckers in the area. Previous work suggested that densities of other woodpeckers, particularly pileated Dryocopus pileatus and red-bellied Melanerpes carolinus woodpeckers, might be useful in characterizing habitat use by the ivory-billed woodpecker. We estimated densities of six woodpecker species in the Big Woods during the breeding seasons of 2006 and 2007 and also during the winter season of 2007. Our estimated densities were as high as or higher than previously published woodpecker density estimates for the Southeastern United States. Density estimates ranged from 9.1 to 161.3 individuals/km2 across six woodpecker species. Our data suggest that the Big Woods of Arkansas is attractive to all woodpeckers using the region, including ivory-billed woodpeckers.
Application of a Double-Observer Aerial Line-Transect Method to Estimate Brown Bear Population Density in Southwestern Alaska
Authors: Walsh Patrick , Reynolds Joel , Collins Gail , Russell Brook , Winfree Michael , Denton Jeffrey
Published: June 2010

Brown bear Ursus arctos population density was estimated for a 21,178-km2 study area in southwest Alaska. Estimates were obtained using an aerial line-transect method that allows for peak detection to be both off the transect line and less than 100%. Data collection required five small aircraft with 2-person crews. Surveys were flown in 10-d windows to capture the period after den emergence but prior to full green-up. Surveys were flown in two consecutive years in order to detect sufficient bear groups to support the estimation. The study detected 197 bear groups (330 bears) in 969 aerial transects averaging 24.8 km long and with a strip width of 728 m. Estimated population density in the study area was 40.4 bears/1,000 km2 (95% CI  =  31.4–54.5); estimated density of independent bears was 27.3 bears/1,000 km2 (95% CI  =  21.4–34.4). Assuming similar estimate precision, repeating the survey could detect population changes of approximately 38% or larger with a power of 80%. We find the method described here suitable for regions of relatively high bear population densities or detection rates.
Ductal adenocarcinoma of the prostate: A clinicopathological study
Authors: Sathesan B , Goonewardena SAS , Anuruddhika HWD , De Silva MVC
Published: June 2010

Objective To study the clinicopathological features of ductal adenocarcinoma of the prostate (DAP). Materials and method All patients with DAP treated in a single urological unit of a tertiary referral center for a period of 12 years and 4 months from September1996 to December 2008 were analyzed. The median follow up was 78 days (range 20 - 391 days). Results 16 patients with DAP (pure ductal - 7, mixed ductal-microacinar - 9) were treated during the study period. The median age of the patient was 69 years (range 56=87 years). During the last 33 months of the study period DAP accounted for 7.2% (pure ductal - 3.6%, mixed ductal-microacinar - 3.6%). Of all DAP four patients had haematuria as the presenting symptom. Digital rectal examination revealed a clinically malignant prostate in 13 patients. Serum PSA varied from 3.26 ng/ml to 311 ng/ml. Urethroscopy revealed papillary growths around the verumontanum or inside the prostatic urethra in 6 patients. 4 patients were surgically castrated and one patient received external beam radiation for the control of disease. Watchful waiting was offered for 3 patients. Conclusion DAP in pure or mixed form accounted for 7.2% of all prostatic carcinomas; 25% of patients presented with haematuria which is an unusual presentation for prostatic microacinar adenocarcinoma. DOI: 10.4038/slju.v9i1.1959 Sri Lanka Journal of Urology, 2008, 9, 20-24
Bladder exstrophy and sexual function
Authors: Abeygunasekera AM , Jayathilake PHC , Pathirathna N , Hettihewa C
Published: June 2010

DOI: 10.4038/slju.v9i1.1960Sri Lanka Journal of Urology, 2008, 9, 25-26
Ecto-5′-Nucleotidase (CD73) Attenuates Allograft Airway Rejection through Adenosine 2A Receptor Stimulation
Authors: Ohtsuka Takashi , Changelian Paul S. , Bouïs Diane , Noon Kathleen , Harada Hiroaki , Lama Vibha N. , Pinsky David J.
Published: June 2010

There are multiple drivers of leukocyte recruitment in lung allografts that contribute to lymphocytic bronchitis (LB) and bronchiolitis obliterans (BO). The innate mechanisms driving (or inhibiting) leukocyte trafficking to allografts remain incompletely understood. This study tested the hypothesis that CD73 (ecto-5′nucleotidase), an enzyme that catalyzes the conversion of AMP to adenosine, is a critical negative regulator of LB and BO. Implantation of tracheal allografts from wild type (WT) mice into CD73−/− recipients revealed a striking increase in airway luminal obliteration at 7 d (62 ± 4% and 47 ± 5% for CD73−/− and WT allograft recipients, respectively; p = 0.046). There was also a concordant increase in CD3+ lymphocytic infiltration (523 ± 41 cells and 313 ± 43 cells for CD73−/− and WT allograft recipients, respectively; p = 0.013). Because real-time PCR revealed a 43-fold upregulation of mRNA for the adenosine A2A receptor (A2AR) in WT allografts compared with WT isografts (p = 0.032), additional experiments were performed to determine whether the protective effect of CD73 was due to generation of adenosine and its stimulation of the A2AR. Treatment of WT recipients with an A2AR agonist significantly reduced CD3+ lymphocyte infiltration and airway luminal obliteration; similar treatment of CD73−/− recipients rescued them from LB and airway obliteration. These data implicate CD73 acting through adenosine generation and its stimulation of the A2AR as a critical negative modulator of lymphocyte recruitment into airway allografts. The CD73/adenosine axis might be a new therapeutic target to prevent BO.
Concomitant Tumor and Autoantigen Vaccination Supports Renal Cell Carcinoma Rejection
Authors: Herbert Nicolás , Haferkamp Axel , Schmitz-Winnenthal Hubertus F. , Zöller Margot
Published: June 2010

Efficient tumor vaccination frequently requires adjuvant. Concomitant induction of an autoimmune response is discussed as a means to strengthen a weak tumor Ag-specific response. We asked whether the efficacy of dendritic cell (DC) vaccination with the renal cell carcinoma Ags MAGE-A9 (MAGE9) and G250 could be strengthened by covaccination with the renal cell carcinoma autoantigen GOLGA4. BALB/c mice were vaccinated with DC loaded with MHC class I-binding peptides of MAGE9 or G250 or tumor lysate, which sufficed for rejection of low-dose RENCA-MAGE9 and RENCA-G250 tumor grafts, but only retarded tumor growth at 200 times the tumor dose at which 100% of animals will develop a tumor. Instead, 75–100% of mice prevaccinated concomitantly with Salmonella typhimurium transformed with GOLGA4 cDNA in a eukaryotic expression vector rejected 200 times the tumor dose at which 100% of animals will develop tumor. In a therapeutic setting, the survival rate increased from 20–40% by covaccination with S. typhimurium-GOLGA4. Autoantigen covaccination significantly strengthened tumor Ag-specific CD4+ and CD8+ T cell expansion, particularly in peptide-loaded DC-vaccinated mice. Covaccination was accompanied by an increase in inflammatory cytokines, boosted IL-12 and IFN-γ expression, and promoted a high tumor Ag-specific CTL response. Concomitant autoantigen vaccination also supported CCR6, CXCR3, and CXCR4 upregulation and T cell recruitment into the tumor. It did not affect regulatory T cells, but slightly increased myeloid-derived suppressor cells. Thus, tumor cell eradication was efficiently strengthened by concomitant induction of an immune response against a tumor Ag and an autoantigen expressed by the tumor cell. Activation of autoantigen-specific Th cells strongly supports tumor-specific Th cells and thereby CTL activation.
Osteopontin Expressed in Tubular Epithelial Cells Regulates NK Cell-Mediated Kidney Ischemia Reperfusion Injury
Authors: Zhang Zhu-Xu , Shek Kelvin , Wang Shuang , Huang Xuyan , Lau Arthur , Yin Ziqin , Sun Hongtao , Liu Weihua , Garcia Bertha , Rittling Susan , Jevnikar Anthony M.
Published: June 2010

Renal ischemia reperfusion injury (IRI) occurs after reduced renal blood flow and is a major cause of acute injury in both native and transplanted kidneys. Studies have shown diverse cell types in both the innate and the adaptive immune systems participate in kidney IRI as dendritic cells, macrophages, neutrophils, B cells, CD4+ NK+ cells, and CD4+ T cells all contribute to this form of injury. Recently, we have found that NK cells induce apoptosis in tubular epithelial cells (TECs) and also contribute to renal IRI. However, the mechanism of NK cell migration and activation during kidney IRI remains unknown. In this study, we have identified that kidney TECs express a high level of osteopontin (OPN) in vitro and in vivo. C57BL/6 OPN-deficient mice have reduced NK cell infiltration with less tissue damage compared with wild-type C57BL/6 mice after ischemia. OPN can directly activate NK cells to mediate TEC apoptotic death and can also regulate chemotaxis of NK cells to TECs. Taken together, our study’s results indicate that OPN expression by TECs is an important factor in initial inflammatory responses that involves NK cells activity in kidney IRI. Inhibiting OPN expression at an early stage of IRI may be protective and preserve kidney function after transplantation.
Mechanical Signals Activate Vascular Endothelial Growth Factor Receptor-2 To Upregulate Endothelial Cell Proliferation during Inflammation
Authors: Liu Jie , Agarwal Sudha
Published: June 2010

Signals generated by the dynamic mechanical strain critically regulate endothelial cell proliferation and angiogenesis; however, the molecular basis remains unclear. We investigated the mechanisms by which human dermal microvascular endothelial cells (HDMECs) perceive mechanical signals and relay them intracellularly to regulate gene expression and endothelial cell proliferation. HDMECs were exposed to low/physiologic levels of dynamic strain and probed for the differential activation/inhibition of kinases in the mechanosignaling cascade associated with endothelial cell gene activation. Because angiogenesis is important at inflammatory sites, we also assessed the mechanisms of mechanosignaling in the presence of an proinflammatory cytokine IL-1β. In this article, we demonstrate that the mechanosignaling cascade is initiated by vascular endothelial growth receptor-2 (VEGFR2) activation. Mechanoactivation of VEGFR2 results in its nuclear translocation and elevation of PI3K-dependent Ser473-Akt phosphorylation. Subsequently, activated Akt inactivates the kinase activity of the serine/threonine kinase, glycogen synthase kinase-3β (GSK3β), via its Ser9 phosphorylation. Thus, inactive GSK3β fails to phosphorylate cyclin D1 and prevents its proteosomal degradation and, consequently, promotes endothelial cell survival and proliferation. In the presence of IL-1β, cyclin D1 is phosphorylated and degraded, leading to inhibition of cell proliferation. However, mechanical signals repress cyclin D1 phosphorylation and upregulate cell proliferation, despite the presence of IL-1β. The data indicate that the VEGFR2/Akt/GSK3β signaling cascade plays a critical role in sensing and phospho-relaying mechanical stimuli in endothelial cells. Furthermore, mechanical forces control highly interconnected networks of proinflammatory and Akt signaling cascades to upregulate endothelial cell proliferation.
Cutting Edge: C1q Binds Deoxyribose and Heparan Sulfate through Neighboring Sites of Its Recognition Domain
Authors: Garlatti Virginie , Chouquet Anne , Lunardi Thomas , Vivès Romain , Païdassi Helena , Lortat-Jacob Hugues , Thielens Nicole M. , Arlaud Gérard J. , Gaboriaud Christine
Published: June 2010

C1q, the recognition subunit of the C1 complex of complement, is an archetypal pattern recognition molecule with the striking ability to sense a wide variety of targets, including a number of altered self-motifs. The recognition properties of its globular domain were further deciphered by means of x-ray crystallography using deoxy-d-ribose and heparan sulfate as ligands. Highly specific recognition of deoxy-d-ribose, involving interactions with Arg C98, Arg C111, and Asn C113, was observed at 1.2 Å resolution. Heparin-derived tetrasaccharide interacted more loosely through Lys C129, Tyr C155, and Trp C190. These data together with previous findings define a unique binding area exhibiting both polyanion and deoxy-d-ribose recognition properties, located on the inner face of C1q. DNA and heparin compete for C1q binding but are poor C1 activators compared with immune complexes. How the location of this binding area in C1q may regulate the level of C1 activation is discussed.
Resistance of CD45RA− T Cells to Apoptosis and Functional Impairment, and Activation of Tumor-Antigen Specific T Cells during Radiation Therapy of Prostate Cancer
Authors: Tabi Zsuzsanna , Spary Lisa K. , Coleman Sharon , Clayton Aled , Mason Malcolm D. , Staffurth John
Published: June 2010

The effect of radiation therapy (RT) to the pelvis on circulating T cells was studied in prostate cancer (PCa) patients to provide a baseline for a more informed design of combination radioimmunotherapy. Peripheral blood samples taken from 12 PCa patients with locally advanced tumor before, during, and after hypofractionated RT were analyzed for T cell phenotype and function. There was significantly more loss of naive and early memory compared with more differentiated T cells during RT. The proportions of annexin-V+ and Fas-expressing T cells were elevated in patients during RT and in PBMC irradiated in vitro (≤5.0 Gy), with preferential increases in CD45RA+ T cells. The baseline level of apoptosis of CD45RA− T cells increased >2-fold in the presence of an IκB-kinase inhibitor, indicating a protective effect via this pathway. T cell proliferation was impaired during RT with IL-2–dependent recovery post-RT. Recall T cell responses to common viral Ags, measured by IFN-γ production, were little affected by RT. In vitro irradiation of healthy donor PBMCs resulted in a significantly increased frequency of responding T cells, due at least partly to the preferential elimination of CD45RA+ T cells. Most importantly, antitumor CD4+ and CD8+ T cell responses were detectable after, but not before or during RT. The results indicate that generating tumor-specific T cell responses before RT and boosting their activity post-RT are ways likely to amplify the frequency and function of antitumor T cells, with implications for scheduling immunotherapy in PCa.
Quantification of PM2.5 organic carbon sampling artifacts in US networks
Authors: Chow J. C. , Watson J. G. , Chen L.-W. A. , Rice J. , Frank N. H.
Published: June 2010

Abstract. Field blanks (bQF) and backup filters (quartz-fiber behind quartz-fiber filter; QBQ) have been adopted by US long-term air quality monitoring networks to estimate PM2.5 organic carbon (OC) sampling artifacts. This study documents bQF and QBQ carbon levels for the: 1) Interagency Monitoring of Protected Visual Environments (IMPROVE); 2) Speciation Trends Network (STN; part of the Chemical Speciation Network [CSN]); and 3) Southeastern Aerosol Research and Characterization (SEARCH) networks and examines the similarities/differences associated with network-specific sampling protocols. A higher IMPROVE sample volume and smaller filter deposit area results in PM2.5 areal density (μg/cm2 on filter) 3–11 times those of STN/CSN and SEARCH samples for the same ambient PM2.5 concentrations, thus reducing the relative contribution of sampling artifacts from passive OC adsorption. A relatively short (1–15 min) passive exposure period of STN/CSN and SEARCH bQF OC (0.8–1 μg/cm2) underestimates positive and negative OC artifacts resulting from passive adsorption or evaporation of semi-volatile organic compounds on quartz-fiber filters. This is supported by low STN/CSN and SEARCH bQF levels and lack of temporal or spatial variability among the sites within the networks. With a much longer period, ~7 days of ambient passive exposure, average IMPROVE bQF and QBQ OC are comparable (2.4±0.5 and 3.1±0.8 μg/cm2, respectively) and more than twice levels found in the STN/CSN and SEARCH networks. Sampling artifacts in STN/CSN were estimated from collocated IMPROVE samples based on linear regression. At six of the eight collocated sites in this study, STN/CSN bQFs underestimated OC artifacts by 11–34%. Using a preceding organic denuder in the SEARCH network minimized passive adsorption on QBQ, but OC on QBQ may not be attributed entirely to the negative sampling artifact (e.g., evaporated or volatilized OC from the front filter deposits after sample collection).
Spatial, temporal, and vertical variability of polar stratospheric ozone loss in the Arctic winters 2004/05–2009/10
Authors: Kuttippurath J. , Godin-Beekmann S. , Lefèvre F. , Goutail F.
Published: June 2010

Abstract. The stratospheric ozone loss during the Arctic winters 2004/05–2009/10 is investigated by using high resolution simulations from the chemical transport model Mimosa-Chim and observations from Microwave Limb Sounder (MLS) on Aura by the passive tracer technique. The winter 2004/05 was the coldest of the series with strongest chlorine activation. The ozone loss diagnosed from both model and measurements inside the polar vortex at 475 K ranges from ~1–0.7 ppmv in the warm winter 2005/06 to 1.7 ppmv in the cold winter 2004/05. Halogenated (chlorine and bromine) catalytic cycles contribute to 75–90% of the accumulated ozone loss at this level. At 675 K the lowest loss of ~0.4 ppmv is computed in 2008/09 from both simulations and observations and, the highest loss is estimated in 2006/07 by the model (1.3 ppmv) and in 2004/05 by MLS (1.5 ppmv). Most of the ozone loss (60–75%) at this level results from cycles catalysed by nitrogen oxides (NO and NO2) rather than halogens. At both 475 and 675 K levels the simulated ozone evolution inside the polar vortex is in reasonably good agreement with the observations. The ozone total column loss deduced from the model calculations at the MLS sampling locations inside the vortex ranges between 40 DU in 2005/06 and 94 DU in 2004/05, while that derived from observations ranges between 37 DU and 111 DU in the same winters. These estimates from both Mimosa-Chim and MLS are in general good agreement with those from the ground-based UV-VIS (ultra violet–visible) ozone loss analyses for the respective winters.
Magnetic field configuration and field-aligned acceleration of energetic ions during substorm onsets
Authors: Korth A. , Pu Z. Y.
Published: June 2010

Abstract. In this paper, we present an interpretation of the observed field-aligned acceleration events measured by GEOS-2 near the night-side synchronous orbit at substorm onsets (Chen et al., 2000). We show that field-aligned acceleration of ions (with pitch angle asymmetry) is closely related to strong short-lived electric fields in the Ey direction. The acceleration is associated with either rapid dipolarization or further stretching of local magnetic field lines. Theoretical analysis suggests that a centrifugal mechanism is a likely candidate for the parallel energization. Equatorward or anti-equatorward energization occurs when the tail current sheet is thinner tailward or earthward of the spacecraft, respectively. The magnetic field topology leading to anti-equatorward energization corresponds to a situation where the near-Earth tail undergoes further compression and the inner edge of the plasma sheet extends inwards as close as the night-side geosynchronous altitudes.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; plasma sheet; storms and sub-storms)
Double discontinuities at the magnetotail plasma sheet-lobe boundary
Authors: Whang Y. C. , Fairfield D. , Lepping R. P. , Mukai T. , Saito Y. , Slavin J. , Szabo A.
Published: June 2010

Abstract. A double discontinuity is a compound structure composed of a slow shock layer and an adjoining rotational discontinuity layer on the postshock side. We use high-resolution data from Geotail and Wind spacecraft to examine the interior structure within the finite thickness of the discontinuity at the plasma sheet-lobe boundary and found that recognizable MHD structures at the boundary can be stand-alone slow shocks or double discontinuities. The plasma density increases significantly and the magnetic field intensity decreases significantly across the interior of the slow shock layer. Through the rotational layer, the magnetic field rotates about the normal direction of the shock surface, as the plasma density and the magnetic field intensity remain nearly unchanged. The rotational angle can vary over a wide range. We notice that the observations of double discontinuities are no less frequent than the observations of stand-alone slow shocks. Identification of slow shocks and double discontinuities infers that plasma and magnetic field lines continuously move across the boundary surface from the lobe into the plasma sheet, and there is a conversion of magnetic field energy into plasma thermal energy through the slow shock layer. The double discontinuities also allows for a rapid rotation of the postshock magnetic field lines immediately behind the shock layer to accommodate the environment of the MHD flow in the plasma sheet region.Key words. Magnetospheric physics (plasma sheet) Space plasma physics (discontinuities; shock waves)
Observation of isotropic electron temperature in the turbulent E region
Authors: Saito S. , Buchert S. C. , Nozawa S. , Fujii R.
Published: June 2010

Abstract. Using EISCAT radar data, we find that electrons are strongly heated in the magnetic field-line direction during high electric field events. The remote site data show that the electron temperature increases in almost the same way in the field-perpendicular direction; electron heating by E region plasma turbulence is isotropic. We discuss the implications of our observation for the "plasmon"-electron as well as the wave Joule heating models of the anomalous electron heating in the E region.Key words. Ionosphere (auroral ionosphere; plasma temperature and density; plasma waves and instabilities)
A note on the interannual variations of UV-B erythemal doses and solar irradiance from ground-based and satellite observations
Authors: Zerefos C. , Balis D. , Tzortziou M. , Bais A. , Tourpali K. , Meleti C. , Bernhard G. , Herman J.
Published: June 2010

Abstract. This study examines three UV-B data sets: ground-based long-term spectral records at Thessaloniki, Greece (40.5° N, 22.9° E) and San Diego, California, USA (32.7° N, 117.2° W) as well as a global data set of daily erythemal dose obtained from the Total Ozone Mapping Spectrometer (TOMS) onboard the Nimbus-7 satellite. Both ground-based stations have long enough records of spectral UV-B measurements to allow independent time series analyses. For 63° solar zenith angle (SZA) and clear sky conditions the quasi biennial oscillation (QBO) effect in solar irradiance at 305nm E305 is about 32% of the annual cycle for both San Diego and Thessaloniki. The effect slightly increases with cloud cover of up to 4/8, and decreases thereafter for cloud cover greater than 4/8. The data reveal that cloudiness can-not offset interannual signals in UV-B records. The observations at San Diego provide an independent confirmation of the widespread nature of the QBO in UV-B, which about coincides in amplitude at the two station studies, both located in the latitude zone 30°– 40° N. The peak-to-peak amplitude of the QBO in erythemal dose derived from TOMS/Nimbus-7 data is 6.5% at Thessaloniki. This is similar to the values calculated from ground-based measurements from this station. Based on satellite data, we find that the amplitude of the QBO in the erythemal dose is almost 40% of the amplitude of the annual cycle only in the tropics. The ratio of the amplitudes of the QBO over the annual cycle in erythemal dose decreases towards the extratropics, becoming less than 5% over middle latitudes.Key words. Atmospheric composition and structure (geo-chemical cycles; transmission and scattering of radiation)
Use of the Acoustic Doppler Current Profiler (ADCP) in the study of the circulation of the Adriatic Sea
Authors: Ursella L. , Gacic M.
Published: June 2010

Abstract. The results of basin-wide vessel-mounted ADCP measurements carried out from May 1995 through February 1996 in the Adriatic Sea are analysed in order to characterise the tidal flow, the steady current field and some specific sub-basin scale features. The M2 tide shows the amphidromic point close to the location predicted from theory. The K1 presents an almost constant phase structure that increases in the northern part from east to west during summer. The circulation in the Italian coastal shelf area is highly variable, due to the local wind forcing and pulses of the Po River discharge. The propagation of the signal associated with the latter, can be described in terms of hybrid internal Kelvin waves, revealed also from the upwelling events. It is also shown that the bottom density-driven current draining the bottom layer of the northern Adriatic is, to a large extent, a time-dependent feature with a temporal scale on the order of days.Key words. Oceanography: general (descriptive and regional oceanography; marginal and semi-enclosed seas) Oceanography: physical (currents)
First results of electric field and density observations by Cluster EFW based on initial months of operation
Authors: Gustafsson G. , André M. , Carozzi T. , Eriksson A. I. , Fälthammar C.-G. , Grard R. , Holmgren G. , Holtet J. A. , Ivchenko N. , Karlsson T. , Khotyaintsev Y. , Klimov S. , Laakso H. , Lindqvist P.-A. , Lybekk B. , Marklund G. , Mozer F. , Mursula K. , Pedersen A. , Popielawska B. , Savin S. , Stasiewicz K. , Tanskanen P. , Vaivads A. , Wahlund J.-E.
Published: June 2010

Abstract. Highlights are presented from studies of the electric field data from various regions along the Cluster orbit. They all point towards a very high coherence for phenomena recorded on four spacecraft that are separated by a few hundred kilometers for structures over the whole range of apparent frequencies from 1 mHz to 9 kHz. This presents completely new opportunities to study spatial-temporal plasma phenomena from the magnetosphere out to the solar wind. A new probe environment was constructed for the CLUSTER electric field experiment that now produces data of unprecedented quality. Determination of plasma flow in the solar wind is an example of the capability of the instrument.Key words. Magnetospheric physics (electric fields) – Space plasma physics (electrostatic structures; turbulence)
First multispacecraft ion measurements in and near the Earth’s magnetosphere with the identical Cluster ion spectrometry (CIS) experiment
Authors: Rème H. , Aoustin C. , Bosqued J. M. , Dandouras I. , Lavraud B. , Sauvaud J. A. , Barthe A. , Bouyssou J. , Camus Th. , Coeur-Joly O. , Cros A. , Cuvilo J. , Ducay F. , Garbarowitz Y. , Medale J. L. , Penou E. , Perrier H. , Romefort D. , Rouzaud J. , Vallat C. , Alcaydé D. , Jacquey C. , Mazelle C. , d’Uston C. , Möbius E. , Kistler L. M. , Crocker K. , Granoff M. , Mouikis C. , Popecki M. , Vosbury M. , Klecker B. , Hovestadt D. , Kucharek H. , Kuenneth E. , Paschmann G. , Scholer M. , Sckopke N. , Seidenschwang E. , Carlson C. W. , Curtis D. W. , Ingraham C. , Lin R. P. , McFadden J. P. , Parks G. K. , Phan T. , Formisano V. , Amata E. , Bavassano-Cattaneo M. B. , Baldetti P. , Bruno R. , Chionchio G. , Di Lellis A. , Marcucci M. F. , Pallocchia G. , Korth A. , Daly P. W. , Graeve B. , Rosenbauer H. , Vasyliunas V. , McCarthy M. , Wilber M. , Eliasson L. , Lundin R. , Olsen S. , Shelley E. G. , Fuselier S. , Ghielmetti A. G. , Lennartsson W. , Escoubet C. P. , Balsiger H. , Friedel R. , Cao J.-B. , Kovrazhkin R. A. , Papamastorakis I. , Pellat R. , Scudder J. , Sonnerup B.
Published: June 2010

Abstract. On board the four Cluster spacecraft, the Cluster Ion Spectrometry (CIS) experiment measures the full, three-dimensional ion distribution of the major magnetospheric ions (H+, He+, He++, and O+) from the thermal energies to about 40 keV/e. The experiment consists of two different instruments: a COmposition and DIstribution Function analyser (CIS1/CODIF), giving the mass per charge composition with medium (22.5°) angular resolution, and a Hot Ion Analyser (CIS2/HIA), which does not offer mass resolution but has a better angular resolution (5.6°) that is adequate for ion beam and solar wind measurements. Each analyser has two different sensitivities in order to increase the dynamic range. First tests of the instruments (commissioning activities) were achieved from early September 2000 to mid January 2001, and the operation phase began on 1 February 2001. In this paper, first results of the CIS instruments are presented showing the high level performances and capabilities of the instruments. Good examples of data were obtained in the central plasma sheet, magnetopause crossings, magnetosheath, solar wind and cusp measurements. Observations in the auroral regions could also be obtained with the Cluster spacecraft at radial distances of 4–6 Earth radii. These results show the tremendous interest of multispacecraft measurements with identical instruments and open a new area in magnetospheric and solar wind-magnetosphere interaction physics.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetopheric configuration and dynamics; solar wind - magnetosphere interactions)
Cluster magnetic field observations of the bowshock: Orientation, motion and structure
Authors: Horbury T. S. , Cargill P. J. , Lucek E. A. , Balogh A. , Dunlop M. W. , Oddy T. M. , Carr C. , Brown P. , Szabo A. , Fornaçon K.-H.
Published: June 2010

Abstract. Four spacecraft Cluster magnetic field observations of the low  quasi-perpendicular terrestrial bowshock are presented for the first time. Multiple quasi-perpendicular crossings on 25 December 2000 are analysed. By combining data from the four spacecraft, bowshock orientations and velocities can be calculated. It is shown that, even while in rapid motion, the bowshock normal direction remains remarkably constant, and that coplanarity estimates are accurate to, typically, around 20°. Magnetic field magnitude profiles are shown to be very well correlated between spacecraft although downstream waves with fluctuations perpendicular to the local field, while statistically similar at all four spacecraft, are poorly correlated on separation scales of several hundred km. Examples are shown of a number of bowshock phenomena, including non-standing fluctuations in the shock foot and the shock interacting with changing solar wind conditions.Key words. Interplanetary physics (planetary bow shocks) Space plasma physics (shock waves; waves and instabilities)
Observations of the spatial and temporal structure of field-aligned beam and gyrating ring distributions at the quasi-perpendicular bow shock with Cluster CIS
Authors: Möbius E. , Kucharek H. , Mouikis C. , Georgescu E. , Kistler L. M. , Popecki M. A. , Scholer M. , Bosqued J. M. , Rème H. , Carlson C. W. , Klecker B. , Korth A. , Parks G. K. , Sauvaud J. C. , Balsiger H. , Bavassano-Cattaneo M.-B. , Dandouras I. , DiLellis A. M. , Eliasson L. , Formisano V. , Horbury T. , Lennartsson W. , Lundin R. , McCarthy M. , McFadden J. P. , Paschmann G.
Published: June 2010

Abstract. During the early orbit phase, the Cluster spacecraft have repeatedly crossed the perpendicular Earth’s bow shock and provided the first multi-spacecraft measurements. We have analyzed data from the Cluster Ion Spectrometry experiment (CIS), which observes the 3D-ion distribution function of the major species in the energy range of 5 eV to 40 keV with a 4 s resolution. Beams of reflected ions were observed simultaneously at all spacecraft locations and could be tracked from upstream to the shock itself. They were found to originate from the same distribution of ions that constitutes the reflected gyrating ions, which form a ring distribution in the velocity space immediately upstream and downstream of the shock. This observation suggests a common origin of ring and beam populations at quasi-perpendicular shocks in the form of specular reflection and immediate pitch angle scattering. Generally, the spatial evolution across the shock is very similar on all spacecraft, but phased in time according to their relative location. However, a distinct temporal structure of the ion fluxes in the field-aligned beam is observed that varies simultaneously on all spacecraft. This is likely to reflect the variations in the reflection and scattering efficiencies.Key words. Interplanetary physics (planetary bow shocks; energetic particles; instruments and techniques)
LHR effects in nonducted whistler propagation – new observations and numerical modelling
Authors: Jiřiček F. , Shklyar D. R. , Třiska P.
Published: June 2010

Abstract. VLF-ELF broadband measurements onboard the MAGION 4 and 5 satellites at heights above 1 Re in plasmasphere provide new data on various known phenomena related to ducted and nonducted whistler wave propagation. Two examples are discussed: magnetospherically reflected (MR) whistlers and lower hybrid resonance (LHR) noise band. We present examples of rather complicated MR whistler spectrograms not reported previously and argue the conditions for their generation. Analytical consideration, together with numerical modelling, yield understanding of the main features of those spectrograms. LHR noise band, as well as MR whistlers, is a phenomenon whose source is the energy propagating in the nonducted way. At the plasmaspheric heights, where hydrogen (H+) is the prevailing ion, and electron plasma frequency is much larger than gyrofrequency, the LHR frequency is close to its maximumvalue in a given magnetic field. This frequency is well followed by the observed noise bands. The lower cutoff frequency of this band is somewhat below that maximum value. The reason for this, as well as the possibility of using the LHR noise bands for locating the plasma through position, are discussed.Key words. Magnetospheric physics (plasmasphere; wave propagation)
Intermittent thermal plasma acceleration linked to sporadic motions of the magnetopause, first Cluster results
Authors: Sauvaud J.-A. , Lundin R. , Rème H. , McFadden J. P. , Carlson C. , Parks G. K. , Möbius E. , Kistler L. M. , Klecker B. , Amata E. , DiLellis A. M. , Formisano V. , Bosqued J. M. , Dandouras I. , Décréau P. , Dunlop M. , Eliasson L. , Korth A. , Lavraud B. , McCarthy M.
Published: June 2010

Abstract. This paper presents the first observations with Cluster of a very dense population of thermal ionospheric ions (H+, He+, O+) locally "accelerated" perpendicularly to the local magnetic field in a region adjacent to the magnetopause and on its magnetospheric side. The observation periods follow a long period of very weak magnetic activity. Recurrent motions of the magnetopause are, in the presented cases, unexpectedly associated with the appearance inside closed field lines of recurrent energy structures of ionospheric ions with energies in the 5 eV to  ~1000 eV range. The heaviest ions were detected with the highest energies. Here, the ion behaviour is interpreted as resulting from local electric field enhancements/decreases which adiabatically enhance/lower the bulk energy of a local dense thermal ion population. This drift effect, which is directly linked to magnetopause motions caused by pressure changes, allows for the thermal ions to overcome the satellite potential and be detected by the suprathermal CIS Cluster experiment. When fast flowing, i.e. when detectable, the density (~ 1 cm-3) of these ions from a terrestrial origin is (in the cases presented here) largely higher than the local density of ions from magnetospheric/plasma sheet origin which poses again the question of the relative importance of solar and ionospheric sources for the magnetospheric plasma even during very quiet magnetic conditions.Key words. Ionosphere (planetary ionosphere; plasma convection) Magnetospheric physics (magnetopause, cusp and boundary layers)
Cluster observations of the high-latitude magnetopause and cusp: initial results from the CIS ion instruments
Authors: Bosqued J. M. , Phan T. D. , Dandouras I. , Escoubet C. P. , Rème H. , Balogh A. , Dunlop M. W. , Alcaydé D. , Amata E. , Bavassano-Cattaneo M.-B. , Bruno R. , Carlson C. , DiLellis A. M. , Eliasson L. , Formisano V. , Kistler L. M. , Klecker B. , Korth A. , Kucharek H. , Lundin R. , McCarthy M. , McFadden J. P. , Möbius E. , Parks G. K. , Sauvaud J.-A.
Published: June 2010

Abstract. Launched on an elliptical high inclination orbit (apogee: 19.6 RE) since January 2001 the Cluster satellites have been conducting the first detailed three-dimensional studies of the high-latitude dayside magnetosphere, including the exterior cusp, neighbouring boundary layers and magnetopause regions. Cluster satellites carry the CIS ion spectrometers that provide high-precision, 3D distributions of low-energy (<35 keV/e) ions every 4 s. This paper presents the first two observations of the cusp and/or magnetopause behaviour made under different interplanetary magnetic field (IMF) conditions. Flow directions, 3D distribution functions, density profiles and ion composition profiles are analyzed to demonstrate the high variability of high-latitude regions. In the first crossing analyzed (26 January 2001, dusk side, IMF-BZ < 0), multiple, isolated boundary layer, magnetopause and magnetosheath encounters clearly occurred on a quasi-steady basis for ~ 2 hours. CIS ion instruments show systematic accelerated flows in the current layer and adjacent boundary layers on the Earthward side of the magnetopause. Multi-point analysis of the magnetopause, combining magnetic and plasma data from the four Cluster spacecraft, demonstrates that oscillatory outward-inward motions occur with a normal speed of the order of ± 40 km/s; the thickness of the high-latitude current layer is evaluated to be of the order of 900–1000 km. Alfvénic accelerated flows and D-shaped distributions are convincing signatures of a magnetic reconnection occurring equatorward of the Cluster satellites. Moreover, the internal magnetic and plasma structure of a flux transfer event (FTE) is analyzed in detail; its size along the magnetopause surface is ~ 12 000 km and it convects with a velocity of ~ 200 km/s. The second event analyzed (2 February 2001) corresponds to the first Cluster pass within the cusp when the IMF-BZ component was northward directed. The analysis of relevant CIS plasma data shows temporal cusp structures displaying a reverse energy-latitude "saw tooth" dispersion, typical for a bursty reconnection between the IMF and the lobe field lines. The observation of D-shaped distributions indicates that the Cluster satellites were located just a few RE from the reconnection site.Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers; magnetosheath) Space plasma physics (magnetic reconnection)
Four point measurements of electrons using PEACE in the high-altitude cusp
Authors: Taylor M. G. G. T. , Fazakerley A. , Krauklis I. C. , Owen C. J. , Travnicek P. , Dunlop M. , Carter P. , Coates A. J. , Szita S. , Watson G. , Wilson R. J.
Published: June 2010

Abstract. We present examples of electron measurements from the PEACE instruments on the Cluster spacecraft in the high-latitude, high-altitude region of the Earth’s magnetosphere. Using electron density and energy spectra measurements, we examine two cases where the orbit of the Cluster tetrahedron is outbound over the northern hemisphere, in the afternoon sector approaching the magnetopause. Data from the magnetometer is also used to pinpoint the position of the spacecraft with respect to magnetospheric boundaries. This preliminary work specifically highlights the benefit of the multipoint measurement capability of the Cluster mission. In the first case, we observe a small-scale spatial structure within the magnetopause boundary layer. The Cluster spacecraft initially straddle a boundary, characterised by a discontinuous change in the plasma population, with a pair of spacecraft on either side. This is followed by a complete crossing of the boundary by all four spacecraft. In the second case, Cluster encounters an isolated region of higher energy electrons within the cusp. The characteristics of this region are consistent with a trapped boundary layer plasma sheet population on closed magnetospheric field lines. However, a boundary motion study indicates that this region convects past Cluster, a characteristic more consistent with open field lines. An interpretation of this event in terms of the motion of the cusp boundary region is presented.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; solar wind-magnetosphere interactions)
Preliminary two-point observations of the mid-altitude cusp by Cluster PEACE and FGM
Authors: Krauklis I. , Fazakerley A. N. , Owen C. J. , Carter P. J. , Dunlop M. W. , Coates A. J. , Szita S. , Taylor M. G. G. T. , Travnicek P. , Watson G. , Wilson R. J.
Published: June 2010

Abstract. On 1 October 2000, Cluster spacecraft Samba (Cluster 3) and Tango (Cluster 4) made an outbound crossing of the northern mid-altitude (4.7 RE) cusp region, moving roughly parallel to the noon meridian. We present preliminary observations from this interval made by the PEACE and FGM instruments. The interplanetary magnetic field at the magnetopause is estimated to have turned south at the time of our observations, based on ACE data as well as a rough estimate of the time taken for the solar wind to travel between ACE and the magnetopause. Cluster 3 encountered the low-latitude boundary layer (LLBL) between 12:20:30 to 12:26:00 UT, and the cusp region between 12:26:00 and 12:32:30 UT. Cluster 4 encountered the LLBL between 12:22:00 to 12:29:00 UT, and the cusp region between 12:29:00 and 12:38:00 UT. During the interval between the two spacecraft passages through these regions, the open/closed field line boundary was observed to move equatorward by 0.33° invariant latitude, while the latitudinal extent of the cusp region increased by 0.5°. Both of these observations are consistent with the ongoing reconnection at the sub-solar magnetopause. The magnetic field data indicate that Cluster encountered four field-aligned longitudinally extended current sheets. The most equatorward of these is consistent with the location of a Region 1 current sheet. Two current sheets were observed in the vicinity of the cusp region, though neither of these were thin current sheets. The fourth current sheet was observed in the mantle region and was largely unaffected by the latitudinal expansion of the cusp region.Key words. Magnetospheric physics (current systems; energetic particles, precipitating; magnetopause, cusp and boundary layers)
Cluster boundary layer measurements and optical observations at magnetically conjugate sites
Authors: Moen J. , Holtet J. A. , Pedersen A. , Lybekk B. , Svenes K. , Oksavik K. , Denig W. F. , Lucek E. , Søraas F. , André M.
Published: June 2010

Abstract. The Cluster spacecraft experienced several boundary layer encounters when flying outbound from the magnetosphere to the magnetosheath in the dusk sector on 14 January 2001. The dayside boundary layer was populated by magnetosheath electrons, but not with quite as high densities as in the magnetosheath itself. The Cluster ground track was calculated using the Tsyganenko-96 model which appears to be a strong tool for combining high-altitude satellite and ground observations, given that the solar wind conditions are known. This paper focuses on identifying auroral responses corresponding to boundary layer dynamics observed by Cluster. The first boundary layer encounter studied was a brief visit into a closed LLBL, most likely due to a boundary wave that travelled tailward over the spacecraft. A corresponding equatorward and eastward movement was seen in the post-noon aurora between Greenland and Svalbard. The second boundary encounter was in a high-latitude cusp, and occurred as a consequence of a transient reconfiguration of the cusp. The cusp expanded duskward over the spacecraft into the late post-noon sector. NOAA-12 probed the 16:30 MLT sector of this auroral activity, and measured a 1.4 keV electron beam located poleward of the 30 keV electron-trapping boundary. A sequence of three moving auroral forms emanating from this active region are likely candidates for flux transfer events. The auroral signatures are discussed in relation to earlier observations, and appear to be an example of accelerated electrons/discrete post-noon aurora on open magnetic field lines.Key words. Ionosphere (particle precipitation) Magnetospheric physics (auroral phenomena; magnetopause, cusp and boundary layers)
Ozone isotopic composition: an angular effect in scattering processes?
Authors: Robert F. , Camy-Peyret C.
Published: June 2010

Abstract. The ratio of the differential scattering cross sections involving distinguishable and indistinguishable isotopes may exhibit non-mass dependent angular variations. A numerical application of this hypotheses to the ozone reaction rates reproduces some of the results observed in laboratory experiments. This theory could be tested through a cross beam experiment where the isotopic composition of the scattered products is recorded as a function of their scattering angles.Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry)
Magnetic field fluctuations across the Earth’s bow shock
Authors: Czaykowska A. , Bauer T. M. , Treumann R. A. , Baumjohann W.
Published: June 2010

Abstract. We present a statistical analysis of 132 dayside (LT 0700-1700) bow shock crossings of the AMPTE/IRM spacecraft. We perform a superposed epoch analysis of low frequency, magnetic power spectra some minutes up-stream and downstream of the bow shock. The events are devided into categories depending on the angle θBn between bow shock normal and interplanetary magnetic field, and on plasma-β. In the foreshock upstream of the quasi-parallel bow shock, the power of the magnetic fluctuations is roughly 1 order of magnitude larger (δB ~ 4 nT for frequencies 0.01–0.04 Hz) than upstream of the quasi-perpendicular shock. There is no significant difference in the magnetic power spectra upstream and downstream of the quasi-parallel bow shock; only at the shock itself, is the magnetic power enhanced by a factor of 4. This enhancement may be due to either an amplification of convecting upstream waves or to wave generation at the shock interface. On the contrary, downstream of the quasi-perpendicular shock, the magnetic wave activity is considerably higher than upstream. Down-stream of the quasi-perpendicular low-β bow shock, we find a dominance of the left-hand polarized component at frequencies just below the ion-cyclotron frequency, with amplitudes of about 3 nT. These waves are identified as ion-cyclotron waves, which grow in a low-β regime due to the proton temperature anisotropy. We find a strong correlation of this anisotropy with the intensity of the left-hand polarized component. Downstream of some nearly perpendicular (θBn ≈ 90°) high-β crossings, mirror waves are identified. However, there are also cases where the conditions for mirror modes are met downstream of the nearly perpendicular shock, but no mirror waves are observed.Key words. Interplanetary physics (plasma waves and turbulence) – Magnetospheric physics (magnetosheath; plasma waves and instabilities)