bluuebunny/crossref_metadata_2025 huggingface dataset:
A contribution by ice nuclei to global warming
Authors: Zeng Xiping , Tao Wei‐Kuo , Zhang Minghua , Hou Arthur Y. , Xie Shaocheng , Lang Stephen , Li Xiaowen , Starr David O'C , Li Xiaofan
Published: June 2009

Ice nuclei (IN) significantly affect clouds via supercooled droplets, that in turn modulate atmospheric radiation and thus climate change. Since the IN effect is relatively strong in stratiform clouds but weak in convective ones, the overall effect depends on the ratio of stratiform to convective cloud amount. In this paper, ten years of TRMM (Tropical Rainfall Measuring Mission) satellite data are analyzed to confirm that stratiform precipitation fraction increases with increasing latitude, which implies that the IN effect is stronger at higher latitudes.

To quantitatively evaluate the IN effect versus latitude, large‐scale forcing data from ten field campaigns are used to drive a cloud‐resolving model to generate long‐term cloud simulations. As revealed in the simulations, the increase in the net downward radiative flux at the top of the atmosphere from doubling the current IN concentrations is larger at higher latitude, which is attributed to the meridional tendency in the stratiform precipitation fraction.

Surface warming from doubling the IN concentrations, based on the radiative balance of the globe, is compared with that from anthropogenic CO2. It is found that the former effect is stronger than the latter in middle and high latitudes but not in the Tropics.

With regard to the impact of IN on global warming, there are two factors to consider: the radiative effect from increasing the IN concentration and the increase in IN concentration itself. The former relies on cloud ensembles and thus varies mainly with latitude. In contrast, the latter relies on IN sources (e.g. the land surface distribution) and thus varies not only with latitude but also longitude. Global desertification and industrialization provide clues on the geographic variation of the increase in IN concentration since pre‐industrial times. Thus, their effect on global warming can be inferred and can then be compared with observations. A general match in geographic and seasonal variations between the inferred and observed warming suggests that IN may have contributed positively to global warming over the past decades, especially in middle and high latitudes. Copyright © 2009 Royal Meteorological Society
Nanoscale Forces and Their Uses in Self‐Assembly
Authors: Bishop Kyle J. M. , Wilmer Christopher E. , Soh Siowling , Grzybowski Bartosz A.
Published: June 2009

The ability to assemble nanoscopic components into larger structures and materials depends crucially on the ability to understand in quantitative detail and subsequently “engineer” the interparticle interactions. This Review provides a critical examination of the various interparticle forces (van der Waals, electrostatic, magnetic, molecular, and entropic) that can be used in nanoscale self‐assembly. For each type of interaction, the magnitude and the length scale are discussed, as well as the scaling with particle size and interparticle distance. In all cases, the discussion emphasizes characteristics unique to the nanoscale. These theoretical considerations are accompanied by examples of recent experimental systems, in which specific interaction types were used to drive nanoscopic self‐assembly. Overall, this Review aims to provide a comprehensive yet easily accessible resource of nanoscale‐specific interparticle forces that can be implemented in models or simulations of self‐assembly processes at this scale.

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Factors influencing infectious complications after pancreatoduodenectomy
Authors: Su Zhongxue , Koga Rintaro , Saiura Akio , Natori Takeshi , Yamaguchi Toshiharu , Yamamoto Junji
Published: June 2009

Background/purpose

Rates of postoperative morbidity, particularly infectious complications, remain high after pancreatoduodenectomy.

Methods

Subjects comprised 101 patients who had undergone pancreatoduodenectomy, analyzed according to presence or absence of infectious postoperative complications. Nineteen perioperative variables were analyzed to identify risk factors associated with postoperative infectious complications.

Results

Postoperative infectious complications occurred in 56 patients (55%); among them 29 had serious infectious morbidity, including bacteremia (13%), intra‐abdominal infection (18%) and pneumonia (12%). One patient (1%) died of multiple organ failure subsequent to a severe septic attack. Only body mass index (BMI) differed significantly between patients with and without serious infection. Logistic regression analysis identified BMI >25 as an independent factor for occurrence of serious postoperative infectious complications. BMI >25 was a common risk factor for individual infection, including bacteremia, intra‐abdominal infection, and pneumonia. As for the influence of BMI on perioperative parameters, the high BMI significantly affected the operation time. Meanwhile preoperative biliary drainage had no influence on overall and individual infectious morbidities.

Conclusions

This study demonstrates the need for careful postoperative monitoring in the patient with high BMI.
Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) as a cause of liver disease in infants in the UK
Authors: Hutchin T. , Preece M. A. , Hendriksz C. , Chakrapani A. , McClelland V. , Okumura F. , Song Y.‐Z. , Iijima M. , Kobayashi K. , Saheki T. , McKiernan P. , Baumann U.
Published: June 2009

Citrin deficiency is a disorder with two phenotypes: neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), and adult‐onset type II citrullinaemia (CTLN2). NICCD presents in the first few weeks of life with prolonged cholestasis and metabolic abnormalities including aminoacidaemia (notably citrulline, tyrosine, threonine, arginine and methionine) and galactosuria. Symptoms resolve within the first year of life, thus making a diagnosis difficult after this time. Although patients subsequently remain generally healthy, some may develop more severe symptoms of CTLN2, characterized by neurological changes, one or more decades later. To date more than 400 cases have been reported, almost all from East Asia (mainly Japan). Here we describe the first two cases of NICCD in infants from the UK, one of caucasian origin and one of Pakistani origin. Both showed typical clinical and biochemical changes with a diagnosis confirmed by the presence of previously unreported mutations in the SLC25A13 gene. The presence of citrin deficiency in other ethnic groups means that NICCD needs to be considered in the diagnosis of any neonate with an unexplained cholestasis. We discuss both the difficulties in diagnosing these patients in populations where very few DNA mutations have been identified and the problems faced in the management of these patients. These findings also raise the possibility of adults with CTLN2 in whom a diagnosis has yet to be made.
Four novel PDHA1 mutations in pyruvate dehydrogenase deficiency
Authors: Ostergaard E. , Moller L. Birk , Kalkanoglu‐Sivri H. Serap , Dursun A. , Kibaek M. , Thelle T. , Christensen E. , Duno M. , Wibrand F.
Published: June 2009

The pyruvate dehydrogenase (PDH) complex is a mitochondrial multienzyme that catalyses the irreversible oxidative decarboxylation of pyruvate to acetyl‐CoA. We report four novel PDHA1 mutations in patients with pyruvate dehydrogenase deficiency. Analysis of PDH activity showed decreased activity in fibroblasts from all four patients, around 16–52% of mean control, similar to what has been found in previous studies. Two of the mutations were missense mutations: c.616G>A (p.Glu206Lys) and c.457A>G (p.Met153Val), one was a 3 bp in‐frame deletion: c.429_431delAGG (p.Gly143del), and one was a 65 bp duplication: c.900–6_958dup65. cDNA analysis of the 65 bp duplication showed a small amount of normal transcript in addition to the transcript corresponding to the duplication. The small amount of normal transcript likely explains the survival of the patient, who was a boy. The duplication and one of the missense mutations were associated with decreased amounts of E1α And E1β protein on western blot analysis, whereas the other two mutations were associated with normal amounts. This study adds four novel mutations to the around 90 reported mutations in PDHA1 (HGMD PDHA1 mutation database). The phenotypes of patients with PDH deficiency have been divided into three groups: a neonatal form with severe lactic acidosis, a form observed only in males and characterized by episodes of ataxia with relapses associated with hyperlactataemia, and an infantile form with hypotonia, lethargy, onset of seizures or dystonia, psychomotor retardation, in some cases Leigh‐like lesions and mild to moderate hyperlactataemia. The four patients reported here all belong to the latter group, which is the largest.
Aromatic Borozene
Authors: Szwacki N Gonzalez , Weber V , Tymczak CJ
Published: June 2009

Based on our comprehensive theoretical investigation and known experimental results for small boron clusters, we predict the existence of a novel aromatic inorganic molecule, B12H6. This molecule, which we refer to as borozene, has remarkably similar properties to the well-known benzene. Borozene is planar, possesses a large first excitation energy, D
3hsymmetry, and more importantly is aromatic. Furthermore, the calculated anisotropy of the magnetic susceptibility of borozene is three times larger in absolute value than for benzene. Finally, we show that borozene molecules may be fused together to give larger aromatic compounds with even larger anisotropic susceptibilities.
miR‐210 promotes osteoblastic differentiation through inhibition of AcvR1b
Authors: Mizuno Yosuke , Tokuzawa Yoshimi , Ninomiya Yuichi , Yagi Ken , Yatsuka-Kanesaki Yukiko , Suda Tatsuo , Fukuda Toru , Katagiri Takenobu , Kondoh Yasumitsu , Amemiya Tomoyuki , Tashiro Hideo , Okazaki Yasushi
Published: June 2009

Although microRNAs (miRNAs) are involved in many biological processes, the mechanisms whereby miRNAs regulate osteoblastic differentiation are poorly understood. Here, we found that BMP‐4‐induced osteoblastic differentiation of bone marrow‐derived ST2 stromal cells was promoted and repressed after transfection of sense and antisense miR‐210, respectively. A reporter assay demonstrated that the activin A receptor type 1B (AcvR1b) gene was a target for miR‐210. Furthermore, inhibition of transforming growth factor‐β (TGF‐β)/activin signaling in ST2 cells with SB431542 promoted osteoblastic differentiation. We conclude that miR‐210 acts as a positive regulator of osteoblastic differentiation by inhibiting the TGF‐β/activin signaling pathway through inhibition of AcvR1b.
Molecular recognition of single‐stranded RNA: Neomycin binding to poly(A)
Authors: Xi Hongjuan , Gray David , Kumar Sunil , Arya Dev P.
Published: June 2009

Poly(A) is a relevant sequence in cell biology due to its importance in mRNA stability and translation initiation. Neomycin is an aminoglycoside antibiotic that is well known for its ability to target various nucleic acid structures. Here it is reported that neomycin is capable of binding tightly to a single‐stranded oligonucleotide (A30) with a Kd in the micromolar range. CD melting experiments support complex formation and indicate a melting temperature of 47 °C. The poly(A) duplex, which melts at 44 °C (pH 5.5), was observed to melt at 61 °C in the presence of neomycin, suggesting a strong stabilization of the duplex by the neomycin.
The unique structure of A-tracts and intrinsic DNA bending
Authors: Haran Tali E. , Mohanty Udayan
Published: June 2009

Short runs of adenines are a ubiquitous DNA element in regulatory regions of many organisms. When runs of 4–6 adenine base pairs (‘A-tracts’) are repeated with the helical periodicity, they give rise to global curvature of the DNA double helix, which can be macroscopically characterized by anomalously slow migration on polyacrylamide gels. The molecular structure of these DNA tracts is unusual and distinct from that of canonical B-DNA. We review here our current knowledge about the molecular details of A-tract structure and its interaction with sequences flanking them of either side and with the environment. Various molecular models were proposed to describe A-tract structure and how it causes global deflection of the DNA helical axis. We review old and recent findings that enable us to amalgamate the various findings to one model that conforms to the experimental data. Sequences containing phased repeats of A-tracts have from the very beginning been synonymous with global intrinsic DNA bending. In this review, we show that very often it is the unique structure of A-tracts that is at the basis of their widespread occurrence in regulatory regions of many organisms. Thus, the biological importance of A-tracts may often be residing in their distinct structure rather than in the global curvature that they induce on sequences containing them.
A Cognitive Behavioural Model and Therapy for Utero-Vaginal Agenesis (Mayer-Rokitansky-Küster-Hauser Syndrome: MRKH)
Authors: Heller-Boersma Jacoline G. , Edmonds D. Keith , Schmidt Ulrike H.
Published: June 2009

Background: Utero-vaginal agenesis, also called the Mayer-Rokitansky-Küster-Hauser Syndrome (MRKH), is a congenital abnormality of the female genital tract, characterized by the non-formation of the vagina and the uterus. It is a common cause of primary amenorrhoea. Little is known about the psychological impact and management of this condition. Method: We describe a specific model of the core negative psychological impact of diagnosis and medical treatment of MRKH and a cognitive-behavioural therapy of MRKH based on the model (CBT-MRKH). The Medical Research Council's (2002) framework for the development and evaluation of complex health interventions was used for intervention development and evaluation. Results: Evidence from a recent cross-sectional study and a small randomized controlled trial (RCT) provides preliminary support for the model and treatment (Heller-Boersma, Schmidt and Edmonds, in press; Heller-Boersma, Schmidt and Edmonds, 2007), and this is further validated by extensive qualitative material gathered over the course of the RCT from participants. Conclusions: The model and treatment described may also be applicable to a number of other congenital or acquired gynaecological conditions such as premature ovarian failure, breast cancer, early onset endometrial cancer, female genital mutilation, Turner's Syndrome, ovarian dys/agenesis or, Complete Androgen Insensitivity Syndrome, all of which have a psychological impact not dissimilar to MRKH in terms of these women's sense of self and femininity.
Fluoreszenzgestützte Resektion bösartiger Hirntumoren – Durchbruch bei der Hirntumor-Operation
Authors: Gautschi  , Leyen van , Cadosch  , Hildebrandt  , Fournier
Published: June 2009

Maligne Gliome, darunter das Glioblastoma multiforme, sind die häufigsten Tumoren des Gehirns. Das Glioblastom stellt dabei den ungünstigsten Tumor dar. In der Schweiz erkranken jedes Jahr ca. 450 Menschen an einem Glioblastoma multiforme. Die mediane Überlebenszeit liegt unter 12 Monaten, die Prognose ist also trotz Kombinationstherapie düster. Die chirurgische Resektion bildet den Hauptbestandteil des Managements von Patienten mit einem Glioblastom. Postoperative Radio- und Chemotherapie haben einen günstigen Einfluss auf die Überlebenszeit sowie auf die Lebensqualität. Glioblastome sind aufgrund ihres infiltrativen Wachstums operativ nur schwer zu entfernen und das angestrebte Resektionsausmass kann meist nur zum Teil ausgeschöpft werden. Seit einiger Zeit wird nun an der Neurochirurgischen Klinik des Kantonsspitals St. Gallen eine neue, in Deutschland entwickelte Methode angewendet: Die 5-ALA-gestützte mikrochirurgische Operationstechnik erlaubt eine zielgesteuerte und sichere operative Entfernung der Tumoranteile. Eine präoperativ verabreichte Substanz färbt den Tumor ein und macht ihn damit für den Neurochirurgen leichter erkennbar. Somit kann das gesunde Hirngewebe besser vom Tumorgewebe abgegrenzt werden. Dies erlaubt nicht nur eine weitestgehende chirurgische Resektion des Tumorgewebes, sondern minimiert auch die Resektion gesunden Gewebes.
Chronischer Alkoholkonsum und Elektrolytdysbalancen – Mögliche Folgen für das ZNS
Authors: Niemann  , Iranyi  , Ott
Published: June 2009

Die zentrale pontine und extrapontine Myelinolyse ist ein wichtiges Krankheitsbild im Zusammenhang mit chronischem Alkoholkonsum oder mit schweren Elektrolytdysbalancen. Obwohl oftmals zunächst eine klinische Verdachtsdiagnose gestellt wird, ist es mittels radiologischer Bildgebung gut möglich, diese Diagnose zu unterstützen.
Temporal and among‐site variability of inherent water use efficiency at the ecosystem level
Authors: Beer C. , Ciais P. , Reichstein M. , Baldocchi D. , Law B. E. , Papale D. , Soussana J.‐F. , Ammann C. , Buchmann N. , Frank D. , Gianelle D. , Janssens I. A. , Knohl A. , Köstner B. , Moors E. , Roupsard O. , Verbeeck H. , Vesala T. , Williams C. A. , Wohlfahrt G.
Published: June 2009

Half‐hourly measurements of the net exchanges of carbon dioxide and water vapor between terrestrial ecosystems and the atmosphere provide estimates of gross primary production (GPP) and evapotranspiration (ET) at the ecosystem level and on daily to annual timescales. The ratio of these quantities represents ecosystem water use efficiency. Its multiplication with mean daylight vapor pressure deficit (VPD) leads to a quantity which we call “inherent water use efficiency” (IWUE*). The dependence of IWUE* on environmental conditions indicates possible adaptive adjustment of ecosystem physiology in response to a changing environment. IWUE* is analyzed for 43 sites across a range of plant functional types and climatic conditions. IWUE* increases during short‐term moderate drought conditions. Mean annual IWUE* varied by a factor of 3 among all sites. This is partly explained by soil moisture at field capacity, particularly in deciduous broad‐leaved forests. Canopy light interception sets the upper limits to canopy photosynthesis, and explains half the variance in annual IWUE* among herbaceous ecosystems and evergreen needle‐leaved forests. Knowledge of IWUE* offers valuable improvement to the representation of carbon and water coupling in ecosystem process models.
Ensemble inversion of time‐dependent core flow models
Authors: Gillet N. , Pais M. A. , Jault D.
Published: June 2009

Quasi‐geostrophic core flow models are built from two secular variation models spanning the periods 1960–2002 and 1997–2008. We rely on an ensemble method to account for the contributions of the unresolved small‐scale magnetic field interacting with core surface flows to the observed magnetic field changes. The different core flow members of the ensemble solution agree up to spherical harmonic degree ℓ ≃ 10, and this resolved component varies only weakly with regularization. Taking into account the finite correlation time of the small‐scale concealed magnetic field, we find that the time variations of the magnetic field occurring over short time scales, such as the geomagnetic jerks, can be accounted for by the resolved (large‐scale) part of the flow to a large extent. Residuals from our flow models are 30% smaller for recent epochs, after 1995. This result is attributed to an improvement in the quality of geomagnetic data. The magnetic field models show little frozen flux violation for the most recent epochs, within our estimate of the apparent magnetic flux changes at the core‐mantle boundary arising from spatial resolution errors. We associate the more important flux changes detected at earlier epochs with uncertainties in the field models at large harmonic degrees. Our core flow models show, at all epochs, an eccentric and planetary‐scale anticyclonic gyre circling around the cylindrical surface tangent to the inner core, at approximately 30 and 60 latitude under the Indian and Pacific oceans, respectively. They account well for the changes in core angular momentum for the most recent epochs.
The decay phase of solar energetic particle events
Authors: Kecskeméty K. , Daibog E. I. , Logachev Y. I. , Kóta J.
Published: June 2009

The shape of the particle flux profile in the decay phase of solar energetic particle (SEP) events is of particular importance in understanding the propagation of energetic particles in the interplanetary medium. The majority of few‐MeV proton events (>90%) exhibit exponential law declines, suggesting the dominant role of convection transport and adiabatic deceleration. In this case, the characteristic decay time τ should depend on the spectral index, the solar wind speed, and the distance from the Sun. More than 600 decays observed in the fluxes of 0.5–48 MeV protons by IMP 8 in 1973–2001 were selected and analyzed in detail. We consider the dependence of τ on environmental plasma parameters. The observed decay times, τobs, are compared with those considering convection transport and adiabatic deceleration, τtheor, and fair agreement is found (within 25%) in nearly 50% of all declines with constant values of V. Although high‐energy proton profiles at various radial distances (Helios, IMP 8, Ulysses) are surprisingly identical, MeV protons in the same events decay more slowly, with increasing r, in agreement with the model. The solar cycle variation and the distribution of the τ values as a function of energy are also examined. The dependence on the heliographic longitude suggests that events with significantly different τobs and τtheor can be explained by the variation of magnetic connection between the observer and a flare site. The observational results are compared with numerical simulations in the frame of a simple particle propagation model involving scattering, adiabatic cooling, and a propagating shock.
Storm time global thermosphere: A driven‐dissipative thermodynamic system
Authors: Burke W. J. , Lin C. S. , Hagan M. P. , Huang C. Y. , Weimer D. R. , Wise J. O. , Gentile L. C. , Marcos F. A.
Published: June 2009

Orbit‐averaged mass densities and exospheric temperatures ∞ inferred from measurements by accelerometers on the Gravity Recovery and Climate Experiment (GRACE) satellites are used to investigate global energy Eth and power Πth inputs to the thermosphere during two complex magnetic storms. Measurements show , ∞, and Eth rising from and returning to prevailing baselines as the magnetospheric electric field ɛVS and the Dst index wax and wane. Observed responses of Eth and ∞ to ɛVS driving suggest that the storm time thermosphere evolves as a driven‐but‐dissipative thermodynamic system, described by a first‐order differential equation that is identical in form to that governing the behavior of Dst. Coupling and relaxation coefficients of the Eth, ∞, and Dst equations are established empirically. Numerical solutions of the equations for ∞ and Eth are shown to agree with GRACE data during large magnetic storms. Since ∞ and Dst have the same ɛVS driver, it is possible to combine their governing equations to obtain estimates of storm time thermospheric parameters, even when lacking information about interplanetary conditions. This approach has the potential for significantly improving the performance of operational models used to calculate trajectories of satellites and space debris and is also useful for developing forensic reconstructions of past magnetic storms. The essential correctness of the approach is supported by agreement between thermospheric power inputs calculated from both GRACE‐based estimates of Eth and the Weimer Poynting flux model originally derived from electric and magnetic field measurements acquired by the Dynamics Explorer 2 satellite.
Analysis of narrowband emission observed in the Saturn magnetosphere
Authors: Menietti J. D. , Ye S.‐Y. , Yoon P. H. , Santolik O. , Rymer A. M. , Gurnett D. A. , Coates A. J.
Published: June 2009

Narrowband emission is observed at Saturn centered near 5 kHz and 20 kHz and harmonics of 20 kHz. This emission appears to be in many ways similar to Jovian narrowband emission observed at higher frequencies. We analyze one example of this emission near a possible source region. In situ electron distributions suggest narrowband emission has a source region associated with electrostatic cyclotron harmonic and upper hybrid emission. Linear growth rate calculations indicate that the observed plasma distributions are unstable to the growth of electrostatic harmonic emissions. In addition, it is found that when the local upper hybrid frequency is close to 2 fce or 3 fce (fce is the electron cyclotron frequency), electromagnetic Z mode and weak ordinary (O mode) emission can be directly generated by the cyclotron maser instability. In the presence of density gradients, Z mode emission can mode‐convert into O mode emission, and this might explain the narrowband emission observed by the Cassini spacecraft.
Determination of rapid Deccan eruptions across the Cretaceous‐Tertiary boundary using paleomagnetic secular variation: 2. Constraints from analysis of eight new sections and synthesis for a 3500‐m‐thick composite section
Authors: Chenet Anne‐Lise , Courtillot Vincent , Fluteau Frédéric , Gérard Martine , Quidelleur Xavier , Khadri S. F. R. , Subbarao K. V. , Thordarson Thor
Published: June 2009

The present paper completes a restudy of the main lava pile in the Deccan flood basalt province (trap) of India. Chenet et al. (2008) reported results from the upper third, and this paper reports the lower two thirds of the 3500‐m‐thick composite section. The methods employed are the same, i.e., combined use of petrology, volcanology, chemostratigraphy, morphology, K‐Ar absolute dating, study of sedimentary alteration horizons, and as the main correlation tool, analysis of detailed paleomagnetic remanence directions. The thickness and volume of the flood basalt province studied in this way are therefore tripled. A total of 169 sites from eight new sections are reported in this paper. Together with the results of Chenet et al. (2008), these data represent in total 70% of the 3500‐m combined section of the main Deccan traps province. This lava pile was erupted in some 30 major eruptive periods or single eruptive events (SEE), each with volumes ranging from 1000 to 20,000 km3and 41 individual lava units with a typical volume of 1300 km3. Paleomagnetic analysis shows that some SEEs with thicknesses attaining 200 m were emplaced over distances in excess of 100 km (both likely underestimates, due to outcrop conditions) and up to 800 km. The total time of emission of all combined SEEs could have been (much) less than 10 ka, with most of the time recorded in a very small number of intervening alteration levels marking periods of volcanic quiescence (so‐called “big red boles”). The number of boles, thickness of the pulses, and morphology of the traps suggest that eruptive fluxes and volumes were larger in the older formations and slowed down with more and longer quiescence periods in the end. On the basis of geochronologic results published by Chenet et al. (2007) and paleontological results from Keller et al. (2008), we propose that volcanism occurred in three rather short, discrete phases or megapulses, an early one at ∼67.5 ± 1 Ma near the C30r/C30n transition and the two largest around 65 ± 1 Ma, one entirely within C29r just before the K‐T boundary, the other shortly afterward spanning the C29r/C29n reversal. We next estimate sulfur dioxide (likely a major agent of environmental stress) amounts and fluxes released by SEEs: they would have ranged from 5 to 100 Gt and 0.1 to 1 Gt/a, respectively, over durations possibly as short as 100 years for each SEE. The chemical input of the Chicxulub impact would have been on the same order as that of a very large single pulse. The impact, therefore, appears as important but incremental, neither the sole nor main cause of the Cretaceous‐Tertiary mass extinctions.
Three‐dimensional P wave attenuation and velocity upper mantle tomography of the southern Apennines–Calabrian Arc subduction zone
Authors: Monna Stephen , Dahm Torsten
Published: June 2009

We propose a 3‐D crust–upper mantle seismic attenuation (QP) model of the southern Apennines–Calabrian Arc subduction zone together with a 3‐D velocity (VP) model. The QP model is calculated from relative t* using the spectral ratio method and the VP from traveltime data. The final data set used for the inversion of the VP model consists of 2400 traveltime arrivals recorded by 34 short‐period stations that are part of the Italian National Seismic Network, and for the QP model, 2178 Pn phases recorded by a subset of 32 stations. Traveltimes and waveforms come from 272 intermediate‐depth Calabrian slab events. This 3‐D model of attenuation, together with the 3‐D velocity model, improves our knowledge of the slab/mantle wedge structure and can be a starting point in determining the physical state of the asthenosphere (i.e., its temperature, the presence of melt and/or fluids) and its relation to volcanism found in the study area. Main features of the QP and VP models show that the mantle wedge/slab, in particular, the area of highest attenuation, is located in a volume underlying the Marsili Basin. The existence and shape of this main low‐QP (and low‐VP) anomaly points to slab dehydration and fluid/material flow, a process that may explain the strong geochemical affinities between the subduction‐related magmas from Stromboli and Vesuvius. Other interesting features in the models are strong lateral variations in QP and VP that are put in relation with known important tectonic structures and volcanic centers in the area.
Three frontside full halo coronal mass ejections with a nontypical geomagnetic response
Authors: Rodriguez L. , Zhukov A. N. , Cid C. , Cerrato Y. , Saiz E. , Cremades H. , Dasso S. , Menvielle M. , Aran A. , Mandrini C. , Poedts S. , Schmieder B.
Published: June 2009

Forecasting potential geoeffectiveness of solar disturbances (in particular, of frontside full halo coronal mass ejections) is important for various practical purposes, e.g., for satellite operations, radio communications, global positioning system applications, power grid, and pipeline maintenance. We analyze three frontside full halo coronal mass ejections (CMEs) that occurred in the year 2000 (close to the activity maximum of solar cycle 23), together with associated solar and heliospheric phenomena as well as their impact on the Earth's magnetosphere. Even though all three were fast full halos (with plane of the sky speeds higher than 1100 km/s), the geomagnetic response was very different for each case. After analyzing the source regions of these halo CMEs, it was found that the halo associated with the strongest geomagnetic disturbance was the one that initiated farther away from disk center (source region at W66); while the other two CMEs originated closer to the central meridian but had weaker geomagnetic responses. Therefore, these three events do not fit into the general statistical trends that relate the location of the solar source and the corresponding geoeffectivity. We investigate possible causes of such a behavior. Nonradial direction of eruption, passage of the Earth through a leg of an interplanetary flux rope, and strong compression at the eastern flank of a propagating interplanetary CME during its interaction with the ambient solar wind are found to be important factors that have a direct influence on the resulting north‐south interplanetary magnetic field (IMF) component and thus on the CME geoeffectiveness. We also find indications that interaction of two CMEs could help in producing a long‐lasting southward IMF component. Finally, we are able to explain successfully the geomagnetic response using plasma and magnetic field in situ measurements at the L1 point. We discuss the implications of our results for operational space weather forecasting and stress the difficulties of making accurate predictions with the current knowledge and tools at hand.
Development of a multiobjective optimization tool for the selection and placement of best management practices for nonpoint source pollution control
Authors: Maringanti Chetan , Chaubey Indrajeet , Popp Jennie
Published: June 2009

Best management practices (BMPs) are effective in reducing the transport of agricultural nonpoint source pollutants to receiving water bodies. However, selection of BMPs for placement in a watershed requires optimization of the available resources to obtain maximum possible pollution reduction. In this study, an optimization methodology is developed to select and place BMPs in a watershed to provide solutions that are both economically and ecologically effective. This novel approach develops and utilizes a BMP tool, a database that stores the pollution reduction and cost information of different BMPs under consideration. The BMP tool replaces the dynamic linkage of the distributed parameter watershed model during optimization and therefore reduces the computation time considerably. Total pollutant load from the watershed, and net cost increase from the baseline, were the two objective functions minimized during the optimization process. The optimization model, consisting of a multiobjective genetic algorithm (NSGA‐II) in combination with a watershed simulation tool (Soil Water and Assessment Tool (SWAT)), was developed and tested for nonpoint source pollution control in the L'Anguille River watershed located in eastern Arkansas. The optimized solutions provided a trade‐off between the two objective functions for sediment, phosphorus, and nitrogen reduction. The results indicated that buffer strips were very effective in controlling the nonpoint source pollutants from leaving the croplands. The optimized BMP plans resulted in potential reductions of 33%, 32%, and 13% in sediment, phosphorus, and nitrogen loads, respectively, from the watershed.
A multistage multicriteria spatial sampling strategy for estimating contaminant mass discharge and its uncertainty
Authors: Li K. Betty , Abriola Linda M.
Published: June 2009

Mass discharge across a control plane has great potential to serve as a metric for the assessment of the impact of partial source zone depletion and for the development of risk‐based source plume remediation strategies. However, field‐estimated mass discharge is always subject to uncertainty, arising from nonexclusive sampling. The accuracy of the estimated discharge and the magnitude of its quantifiable uncertainty depend upon the amount of information provided by the sample data. A multistage spatial sampling strategy is proposed to select optimal sampling locations and determine minimal sampling density for accurate quantification of mass discharge uncertainty. Two sampling criteria are incorporated to ensure coverage of the control plane and delineation of highly concentrated areas (hot spots). Multiple criteria decision making theory is adapted to objectively weight the two sampling criteria, on the basis of the information importance of each criterion, with additional observations located according to the weighted average of the two criteria. Application of this methodology to numerically simulated plume transects shows that in comparison to one stage sampling design (regular pattern), this sampling strategy yields a 50% reduction in required sampling density for accurate uncertainty modeling. The developed sampling algorithm can be used in real time to guide staged field sampling.
New and revised 14C dates for Hawaiian surface lava flows: Paleomagnetic and geomagnetic implications
Authors: Pressling N. , Trusdell F. A. , Gubbins D.
Published: June 2009

Radiocarbon dates have been obtained for 30 charcoal samples corresponding to 27 surface lava flows from the Mauna Loa and Kilauea volcanoes on the Island of Hawaii. The submitted charcoal was a mixture of fresh and archived material. Preparation and analysis was undertaken at the NERC Radiocarbon Laboratory in Glasgow, Scotland, and the associated SUERC Accelerator Mass Spectrometry facility. The resulting dates range from 390 years B.P. to 12,910 years B.P. with corresponding error bars an order of magnitude smaller than previously obtained using the gas‐counting method. The new and revised 14C data set can aid hazard and risk assessment on the island. The data presented here also have implications for geomagnetic modelling, which at present is limited by large dating errors.
Arctic stratospheric winter warming forced by observed SSTs
Authors: Hu Yongyun , Pan Lingfen
Published: June 2009

Observations showed warming trends in the Arctic stratosphere in early winter months in the past few decades, in contrast to cooling trends in late winter months mainly due to ozone depletion. To examine whether observed warming trends is caused by sea surface temperature (SST) increases, we analyze results from AMIP simulations which are forced by observed time‐varying SSTs. It is found that all AMIP simulations demonstrate warming trends in the Arctic lower stratosphere. It also shows a weakened Arctic polar vortex, in responding to the polar warming. Empirical Orthogonal function (EOF) analysis shows a downward trend toward the negative polarity of an annular‐like mode. Further analyses indicate that the Arctic stratospheric warming is associated with increasing wave activity and enhanced wave‐flux convergence in the extratropical stratosphere, suggesting that the polar warming is caused by enhanced wave‐driven adiabatic heating due to SST increases.
Probabilistic downscaling approaches: Application to wind cumulative distribution functions
Authors: Michelangeli P.‐A. , Vrac M. , Loukos H.
Published: June 2009

A statistical method is developed to generate local cumulative distribution functions (CDFs) of surface climate variables from large‐scale fields. Contrary to most downscaling methods producing continuous time series, our “probabilistic downscaling methods” (PDMs), named “CDF‐transform”, is designed to deal with and provide local‐scale CDFs through a transformation applied to large‐scale CDFs. First, our PDM is compared to a reference method (Quantile‐matching), and validated on a historical time period by downscaling CDFs of wind intensity anomalies over France, for reanalyses and simulations from a general circulation model (GCM). Then, CDF‐transform is applied to GCM output fields to project changes in wind intensity anomalies for the 21st century under A2 scenario. Results show a decrease in wind anomalies for most weather stations, ranging from less than 1% (in the South) to nearly 9% (in the North), with a maximum in the Brittany region.
Longitude variations of the solar semidiurnal tides in the mesosphere and lower thermosphere at low latitudes observed from ground and space
Authors: Friedman Jonathan S. , Zhang Xiaoli , Chu Xinzhao , Forbes Jeffrey M.
Published: June 2009

We present an analysis of longitudinal variation in the solar semidiurnal tide observed in the nocturnal thermal structure of the low‐latitude mesopause region (83–103 km), with a focus on two sites: Arecibo, Puerto Rico (18.3°N, 66.8°W) and Maui, Hawaii (20.7°N, 156.3°W). Localized observations made by lidars are combined with longitudinal measurements by Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) and compared with the Global‐Scale Wave Model‐2002 (GSWM‐02) for 6 months: January, April, May, July, August, and October. In winter‐spring, lidar‐measured amplitudes are larger than those recorded by SABER, whereas in summer the amplitudes are similar and in autumn the lidars observe smaller amplitudes than SABER. GSWM amplitudes are between the lidar and SABER measurements for January, are comparable to the measurements in spring, underpredict for summer, and agree with the lidars in autumn. The phase structure is consistent among lidars and SABER for all of the months except January, when there is a large phase shift, and the local time of the temperature maximum is different between Arecibo and Maui. GSWM shows better agreement with phase measurements in winter‐spring than in summer‐autumn. Modal analysis of the SABER data indicates that the (2, 2) Hough mode is present throughout the year. In winter, it is joined by the (2, 4) mode, while in summer it is accompanied by the (2, 3) mode. This change in the predominant Hough modes may be related to the winter‐summer phase difference.
Persistent Increase in Oxygen Consumption and Impaired Neurovascular Coupling after Spreading Depression in Rat Neocortex
Authors: Piilgaard Henning , Lauritzen Martin
Published: June 2009

Cortical spreading depression (CSD) is associated with a dramatic failure of brain ion homeostasis and increased energy metabolism. There is strong clinical and experimental evidence to suggest that CSD is the mechanism of migraine, and involved in progressive neuronal injury in stroke and head trauma. Here we tested the hypothesis that single episodes of CSD induced acute hypoxia, and prolonged impairment of neurovascular and neurometabolic coupling. Cortical spreading depression was induced in rat frontal cortex, whereas cortical electrical activity and local field potentials (LFPs) were recorded by glass microelectrodes, cerebral blood flow (CBF) by laser—Doppler flowmetry, and tissue oxygen tension (tpO2) with Polarographic microelectrodes. Cortical spreading depression increased cerebral metabolic rate of oxygen (CMRO2) by 71% ± 6.7% and CBF by 238% ± 48.1% for 1 to 2 mins. For the following 2 h, basal tpO2 and CBF were reduced whereas basal CMRO2 was persistently elevated by 8.1% ± 2.9%. In addition, within first hour after CSD we found impaired neurovascular coupling (LFP versus CBF), whereas neurometabolic coupling (LFP versus CMRO2) remained unaffected. Impaired neurovascular coupling was explained by both reduced vascular reactivity and suppressed function of cortical inhibitory interneurons. The protracted effects of CSD on basal CMRO2 and neurovascular coupling may contribute to cellular dysfunction in patients with migraine and acutely injured cerebral cortex.
Roles of Matrix Metalloproteinases in Flow-Induced Outward Vascular Remodeling
Authors: Ota Ryo , Kurihara Chie , Tsou Tsung-Ling , Young William L , Yeghiazarians Yerem , Chang Mayland , Mobashery Shahriar , Sakamoto Atsuhiro , Hashimoto Tomoki
Published: June 2009

Sustained hemodynamic stresses, especially high blood flow, result in flow-induced outward vascular remodeling. Our previous study showed that macrophage depletion reduced flow-induced outward remodeling of the rat common carotid artery, indicating that macrophages are critical in flow-induced outward vascular remodeling. Macrophage is known to release proteinases, including matrix metalloproteinases (MMPs). Degradation and loosening of extracellular matrix by MMPs may facilitate vascular remodeling. Therefore, we assessed the functions of MMPs in flow-induced outward vascular remodeling by using the flow-augmented common carotid artery model in mice. We validated that ligation of the left common carotid artery increased blood flow and luminal diameter of the right common carotid artery without significant change in blood pressure of mice. To assess the functions of MMPs in flow-induced outward vascular remodeling, we used doxycycline (broad-spectrum MMP inhibitor), SB-3CT (selective MMP inhibitor), MMP-9 knockout mice, and MMP-12 knockout mice. Although there was only a trend for doxycycline treatment to reduce flow-induced outward vascular remodeling, SB-3CT treatment significantly reduced flow-induced outward vascular remodeling. In addition, flow-induced outward vascular remodeling was significantly reduced in MMP-9 knockout mice, but not in MMP-12 knockout mice. These data revealed that MMPs, especially MMP-9, are critical in flow-induced outward vascular remodeling.
Anomalous power dependence of upconversion emissions in Gd2O3:Er3+ nanocrystals under diode laser excitation of 970 nm
Authors: Chen G. Y. , Liang H. J. , Liu H. C. , Somesfalean G. , Zhang Z. G.
Published: June 2009

Visible green and red upconversion (UC) emissions with anomalous power dependence were observed in Gd2O3:Er3+ nanocrystals at room temperature under diode laser excitation of 970 nm. The green and red UC radiations both yield an “s”-shape power dependence, in marked contrast to the quadratic ones of the bulk counterparts. A closed positive looping UC mechanism that differs from conventional PA mechanism is proposed to explain the observed five- or six-photon processes in the “s”-shape power dependence. Power dependence analysis of the 1.55 μm emissions from the I413/2 state experimentally demonstrates our proposed model.
CoCrPt antidot arrays with perpendicular magnetic anisotropy made on anodic alumina templates
Authors: Navas D. , Ilievski F. , Ross C. A.
Published: June 2009

Ti(5 nm)/CoCrPt(5–20 nm) bilayers with perpendicular magnetic anisotropy were deposited by rf sputtering onto porous alumina films to form antidot arrays with period 105 nm and pore diameters ranging from 18 to 56 nm. The coercivities of the antidot arrays are greater than those of unpatterned films and show only a weak dependence on antidot diameter. Magnetic force microscopy of ac-demagnetized samples shows that the antidot arrays have domain sizes larger than the 105 nm period. The magnetic behavior is discussed in terms of domain wall pinning by the antidots.
Timing property of undoped BaCl2 single crystal scintillator
Authors: Koshimizu Masanori , Onodera Kazuya , Shibuya Kengo , Saito Haruo , Asai Keisuke
Published: June 2009

Scintillation characteristics of undoped BaCl2, a novel fast scintillation material, were investigated. Scintillation photons with wavelength ranging from 250–600 nm were observed with two luminescence bands at 300 and 400 nm. The scintillation time profiles consisted of two lifetime components. The shorter component had a lifetime of 1.6 ns, while the longer one had a lifetime of several tens of nanoseconds. The origin of the fast component has been attributed to self-trapped excitons, whereas the slow component is considered to be an extrinsic luminescence. The photoelectron yield of the fast component of BaCl2 coupled to a bialkali photocathode was comparable to that of BaF2. This shows that BaCl2 is a promising scintillation material that can be used for measurements at a high counting rate or with an excellent timing property.
Low frequency noise in arrays of magnetic tunnel junctions connected in series and parallel
Authors: Guerrero R. , Pannetier-Lecoeur M. , Fermon C. , Cardoso S. , Ferreira R. , Freitas P. P.
Published: June 2009

Low frequency noise and small output voltage are the strongest limitations to the use of magnetic tunnel junctions (MTJs) for magnetic sensor applications, replacing giant magnetoresistance (GMR) and anisotropic magnetoresistance sensors. In this paper, we explore the possibility of using arrays with a large number of MTJs connected in parallel/series to overcome these limitations. MTJ’s sensor arrays of more than 3×103 junction elements in different configurations have been fabricated. Low frequency noise and detectivity have been measured and compared to an analytical model, with detectivities of about 16 nT/Hz1/2 achieved in a series/parallel architecture. This detectivity levels are competitive with single devices based on GMR, with the advantage of not requiring additional flux concentrators.