bluuebunny/crossref_metadata_2025 huggingface dataset:
Cosmic rays linked to rapid mid-latitude cloud changes
Authors: Laken B. A. , Kniveton D. R. , Frogley M. R.
Published: November 2010

Abstract. The effect of the Galactic Cosmic Ray (GCR) flux on Earth's climate is highly uncertain. Using a novel sampling approach based around observing periods of significant cloud changes, a statistically robust relationship is identified between short-term GCR flux changes and the most rapid mid-latitude (60°–30° N/S) cloud decreases operating over daily timescales; this signal is verified in surface level air temperature (SLAT) reanalysis data. A General Circulation Model (GCM) experiment is used to test the causal relationship of the observed cloud changes to the detected SLAT anomalies. Results indicate that the anomalous cloud changes were responsible for producing the observed SLAT changes, implying that if there is a causal relationship between significant decreases in the rate of GCR flux (~0.79 GU, where GU denotes a change of 1% of the 11-year solar cycle amplitude in four days) and decreases in cloud cover (~1.9 CU, where CU denotes a change of 1% cloud cover in four days), an increase in SLAT (~0.05 KU, where KU denotes a temperature change of 1 K in four days) can be expected. The influence of GCRs is clearly distinguishable from changes in solar irradiance and the interplanetary magnetic field. However, the results of the GCM experiment are found to be somewhat limited by the ability of the model to successfully reproduce observed cloud cover. These results provide perhaps the most compelling evidence presented thus far of a GCR-climate relationship. From this analysis we conclude that a GCR-climate relationship is governed by both short-term GCR changes and internal atmospheric precursor conditions.
A decadal regional and global trend analysis of the aerosol optical depth using a data-assimilation grade over-water MODIS and Level 2 MISR aerosol products
Authors: Zhang J. , Reid J. S.
Published: November 2010

Abstract. Using the ten-year (2000–2009) Data-Assimilation (DA) quality Terra MODIS and MISR aerosol products, as well as 7 years of Aqua MODIS, we studied both regional and global aerosol trends over oceans. This included both operational and data assimilation grade versions of the products. After correcting for what appears to be aerosol signal drift from the radiometric calibration of both MODIS instruments, we found MODIS and MISR agreed on a statistically negligible global trend of ±0.003/per decade. Our study also suggests that AODs over the Indian Bay of Bengal, east coast of Asia, and Arabian Sea show increasing trends of 0.07, 0.06, and 0.06 per decade for MODIS, respectively. These regional trends are considered as significant with a confidence level above 95%. Similar increasing trends were found from MISR, but with less relative magnitude. These trends reflect respective increases in the optical intensity of aerosol events in each region: anthropogenic aerosols over the east coast of China and Indian Bay of Bengal; and a stronger influence from dust events over the Arabian Sea. Negative AOD trends, low in confidence levels, are found off Central America, the east coast of North America, and the west coast of Africa, which indicate that longer periods of observation are necessary to be conclusive.
Direct satellite observation of lightning-produced NOx
Authors: Beirle S. , Huntrieser H. , Wagner T.
Published: November 2010

Abstract. Lightning is an important source of NOx in the free troposphere, especially in the tropics, with strong impact on ozone production. However, estimates of lightning NOx (LNOx) production efficiency (LNOx per flash) are still quite uncertain. In this study we present a systematic analysis of NO2 column densities from SCIAMACHY measurements over active thunderstorms, as detected by the World-Wide Lightning Location Network (WWLLN), where the WWLLN detection efficiency was estimated using the flash climatology of the satellite lightning sensors LIS/OTD. Only events with high lightning activity are considered, where corrected WWLLN flash rate densities inside the satellite pixel within the last hour are above 1 /km2/h. For typical SCIAMACHY ground pixels of 30 × 60 km2, this threshold corresponds to 1800 flashes over the last hour, which, for literature estimates of lightning NOx production, should result in clearly enhanced NO2 column densities. From 2004–2008, we find 287 coincidences of SCIAMACHY measurements and high WWLLN flash rate densities. For some of these events, a clear enhancement of column densities of NO2 could be observed, indeed. But overall, the measured column densities are below the expected values by more than one order of magnitude, and in most of the cases, no enhanced NO2 could be found at all. Our results are in contradiction to the currently accepted range of LNOx production per flash of 15 (2–40)×1025 molec/flash. This probably partly results from the specific conditions for the events under investigation, i.e. events of high lightning activity in the morning (local time) and mostly (for 162 out of 287 events) over ocean. Within the detected coincidences, the highest NO2 column densities were observed around the US Eastcoast. This might be partly due to interference with ground sources of NOx being uplifted by the convective systems. However, it could also indicate that flashes in this region are particularly productive. We conclude that current estimates of LNOx production might be biased high for two reasons. First, we observe a high variability of NO2 for coincident lightning events. This high variability can easily cause a publication bias, since studies reporting on high NOx production have likely been published, while studies finding no or low amounts of NOx might have been rejected as errorneous or not significant. Second, many estimates of LNOx production in literature have been performed over the US, which is probably not representative for global lightning.
Quantitative assessment of upstream source influences on total gaseous mercury observations in Ontario, Canada
Authors: Wen D. , Lin J. C. , Meng F. , Gbor P. K. , He Z. , Sloan J. J.
Published: November 2010

Abstract. Hourly total gaseous mercury (TGM) concentrations at three monitoring sites (receptors) in Ontario were predicted for four selected periods at different seasons in 2002 using the Stochastic Time-Inverted Lagrangian Transport (STILT) model, which transports Lagrangian air parcels backward in time from the receptors to provide linkages to the source region in the upwind area. The STILT model was modified to deal with Hg deposition and high stack Hg emissions. The model-predicted Hg concentrations were compared with observations at three monitoring sites. Estimates of transport errors (uncertainties in simulated concentrations due to errors in wind fields) are also provided that suggest such errors can reach approximately 10% of simulated concentrations. Results from a CMAQ chemical transport model (CTM) simulation in which the same emission and meteorology inputs were used are also reported. The comparisons show that STILT-predicted Hg concentrations usually agree better with observations than CMAQ except for a subset of cases that are subject to biases in the coarsely resolved boundary conditions. STILT captures high frequency concentration variations better than the Eulerian CTM, due to its ability to account for near-field influences that are not resolved by typical grid sizes in Eulerian CTMs. Thus it is particularly valuable for the interpretation of plumes (short-term concentration variations) that require complex sub-grid treatments in Eulerian models. We report quantitative assessments of the relative importance of different upstream sources for the selected episodes, based on emission fluxes and STILT footprints. The STILT simulations indicate that natural sources (which include re-emission from historical anthropogenic activities) contribute much more than current-day anthropogenic emissions to the Hg concentrations observed at the three sites.
Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions
Authors: Hao L. Q. , Romakkaniemi S. , Yli-Pirilä P. , Joutsensaari J. , Kortelainen A. , Kroll J. H. , Miettinen P. , Vaattovaara P. , Tiitta P. , Jaatinen A. , Kajos M. K. , Holopainen J. K. , Heijari J. , Rinne J. , Kulmala M. , Worsnop D. R. , Smith J. N. , Laaksonen A.
Published: November 2010

Abstract. Biogenic volatile organic compounds (VOCs) are a significant source of global secondary organic aerosol (SOA); however, quantifying their aerosol forming potential remains a challenge. This study presents smog chamber laboratory work, focusing on SOA formation via oxidation of the emissions of two dominant tree species from boreal forest area, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies), by hydroxyl radical (OH) and ozone (O3). Oxidation of α-pinene was also studied as a reference system. Tetramethylethylene (TME) and 2-butanol were added to control OH and O3 levels, thereby allowing SOA formation events to be categorised as resulting from either OH-dominated or O3-initiated chemistry. SOA mass yields from α-pinene are consistent with previous studies while the yields from the real plant emissions are generally lower than that from α-pinene, varying from 1.9% at an aerosol mass loading of 0.69 μg m−3 to 13.6% at 32.8 μg m−3. Mass yields from oxidation of real plant emissions are subject to the interactive effects of the molecular structures of plant emissions and their reaction chemistry with OH and O3, which lead to variations in condensable product volatility. SOA formation can be reproduced with a two-product gas-phase partitioning absorption model in spite of differences in the source of oxidant species and product volatility in the real plant emission experiments. Condensable products from OH-dominated chemistry showed a higher volatility than those from O3-initiated systems during aerosol growth stage. Particulate phase products became less volatile via aging process which continued after input gas-phase oxidants had been completely consumed.
Probabilistic prediction of raw and BMA calibrated AEMET-SREPS: the 24 of January 2009 extreme wind event in Catalunya
Authors: Escribà P. , Callado A. , Santos D. , Santos C. , García-Moya J. A. , Simarro J.
Published: November 2010

Abstract. At 00:00 UTC of 24 January 2009 (24Jan09) an explosive cyclogenesis placed at the Gulf of Vizcaya, reached its maximum intensity with observed surface pressures below 970 hPa on its center. During its path through the south of France there were strong westerly and north-westerly winds over Iberian Peninsula (above 150 km/h). These extreme winds leaved 8 casualties in Catalunya, the north-east region of Spain. The aim of this work is validating the skill of the Spanish Meteorological Agency (AEMET) Short Range Ensemble Prediction System (SREPS) in forecasting this event. Two probabilistic forecasts of wind are compared, a non-calibrated (or raw) and a calibrated one using the Bayesian Model Averaging (BMA). AEMET runs a daily experimental SREPS twice a day (00:00 and 12:00 UTC). This system consists on 25 members that are constructed by integrating five different Limited Area Models (LAMs) at 0.25 degrees of horizontal resolution. Each model uses five different initial and boundary conditions from five Global Models (GMs). Thus it is obtained a probabilistic forecast that takes into account initial, contour and model uncertainties. BMA is a statistical tool for combining predictive Probability Distribution Functions (PDFs) from different sources. BMA predictive PDF is a weighted average of PDFs centered on the individual bias-corrected forecasts. Each weight is a measure of the corresponding forecast skill. Here BMA is applied to calibrate probabilistic forecasts of wind speed. In this work two time forecast ranges (H+60 and H+36) of 10-m wind speed over Catalonia are verified subjectively at 12:00 UTC of 24Jan09 valid time. We focus on the location and intensity of 10-m wind speed maximum values. Observations at 29 automatic ground stations of AEMET are used for the verification. On one hand results indicate that raw AEMET-SREPS is able to forecast 60 h ahead mean winds higher than 36 and 54 km/h and that it correctly locates them in three different areas. On the other hand, predicted probability loses its skill after BMA calibration of the ensemble. This is due to the fact that BMA bias correction underestimates the intensity of wind.
A two year's source apportionment study of wood burning and traffic aerosols for urban and rural sites in Switzerland
Authors: Herich H. , Hueglin C. , Buchmann B.
Published: November 2010

Abstract. The contributions of fossil fuel (FF) and wood burning (WB) emissions to black carbon (BC) have been investigated in the past by analysis of multi-wavelength aethalometer data. This approach utilize the stronger light absorption of WB aerosols in the near ultraviolet compared to the light absorption of aerosols from FF combustion. Here we present two years of seven-wavelength aethalometer data from one urban and two rural background sites in Switzerland measured from 2008–2010. The contribution of WB and FF to BC was directly determined from the absorption coefficients of FF and WB aerosols which were calculated by using confirmed absorption exponents and aerosol light absorption cross-sections that were determined for all sites. Reasonable separation of total BC into contributions from FF and WB was achieved for all sites and seasons. The obtained WB contributions to BC are well correlated with measured concentrations of levoglucosan and potassium while FF contributions to BC correlate nicely with NOx. These findings support our approach and show that the applied source apportionment of BC is well applicable for long-term data sets. During winter, we found that BC from WB contributes on average 24–29% to total BC at the considered measurement sites. This is a noticeable high fraction as the contribution of wood burning to the total final energy consumption is in Switzerland less than 4%.
Resistive MHD reconstruction of two-dimensional coherent structures in space
Authors: Teh W.-L. , Sonnerup B. U. Ö. , Birn J. , Denton R. E.
Published: November 2010

Abstract. We present a reconstruction technique to solve the steady resistive MHD equations in two dimensions with initial inputs of field and plasma data from a single spacecraft as it passes through a coherent structure in space. At least two components of directly measured electric fields (the spacecraft spin-plane components) are required for the reconstruction, to produce two-dimensional (2-D) field and plasma maps of the cross section of the structure. For convenience, the resistivity tensor η is assumed diagonal in the reconstruction coordinates, which allows its values to be estimated from Ohm's law, E+v×B=η·j. In the present paper, all three components of the electric field are used. We benchmark our numerical code by use of an exact, axi-symmetric solution of the resistive MHD equations and then apply it to synthetic data from a 3-D, resistive, MHD numerical simulation of reconnection in the geomagnetic tail, in a phase of the event where time dependence and deviations from 2-D are both weak. The resistivity used in the simulation is time-independent and localized around the reconnection site in an ellipsoidal region. For the magnetic field, plasma density, and pressure, we find very good agreement between the reconstruction results and the simulation, but the electric field and plasma velocity are not predicted with the same high accuracy.
Organic matter accumulation and degradation in subsurface coastal sediments: a model-based comparison of rapid sedimentation and aquifer transport
Authors: Holstein J. M. , Wirtz K. W.
Published: November 2010

Abstract. The redox succession in shallow marine sediments generally exhibits a predictable pattern. Pore water profiles from a back barrier tidal flat in the German Wadden Sea depart from the expected redox zoning. Instead, a sulfate minimum zone associated with a sulfate-methane-sulfate double interface and a distinct ammonium peak at 1.5 m below sea floor (mbsf) is displayed. Such evidence for significant degradation of organic matter (OM) in subsurface layers is challenging our understanding of tidal flat biogeochemistry as little is known about processes that relocate reactive OM into layers far distant from the sediment-water interface. The objectives of our model study were to identify possible mechanisms for the rapid transport of organic matter to subsurface layers that cause the reversed redox succession and to constrain several important biogeochemical control parameters. We compared two scenarios for OM transfer: rapid sedimentation and burial of OM as well as lateral advection of suspended POM. Using a diagenetic model, uncertain process parameters, in particular those connected to OM degradation and (vertical or lateral) transport, are systematically calibrated using field data. We found that both scenarios, advection and sedimentation, had solutions consistent with the observed pore water profiles. For this specific site, however, advective transport of particulate material had to be rejected since the reconstructed boundary conditions were rather improbable. In the alternative deposition set-up, model simulations suggested the deposition of the source OM about 60 yrs before cores were taken. A mean sedimentation rate of approximately 2 cm yr−1 indicates substantial changes in near coast tidal flat morphology, since sea level rise is at a much lower pace. High sedimentation rates most probably reflect the progradation of flats within the study area. These or similar morphodynamic features also occur in other coastal areas so that inverted redox succession by horizontal or vertical transport may be more common than previously thought. Consequently, regional values for OM remineralization rates may be higher than predicted from surface biogeochemistry.
Fractal Metrology for biogeosystems analysis
Authors: Torres-Argüelles V. , Oleschko K. , Tarquis A. M. , Korvin G. , Gaona C. , Parrot J.-F. , Ventura-Ramos E.
Published: November 2010

Abstract. The solid-pore distribution pattern plays an important role in soil functioning being related with the main physical, chemical and biological multiscale and multitemporal processes of this complex system. In the present research, we studied the aggregation process as self-organizing and operating near a critical point. The structural pattern is extracted from the digital images of three soils (Chernozem, Solonetz and "Chocolate" Clay) and compared in terms of roughness of the gray-intensity distribution quantified by several measurement techniques. Special attention was paid to the uncertainty of each of them measured in terms of standard deviation. Some of the applied methods are known as classical in the fractal context (box-counting, rescaling-range and wavelets analyses, etc.) while the others have been recently developed by our Group. The combination of these techniques, coming from Fractal Geometry, Metrology, Informatics, Probability Theory and Statistics is termed in this paper Fractal Metrology (FM). We show the usefulness of FM for complex systems analysis through a case study of the soil's physical and chemical degradation applying the selected toolbox to describe and compare the structural attributes of three porous media with contrasting structure but similar clay mineralogy dominated by montmorillonites.
Change in hydraulic properties and leaf traits of a tall rainforest tree species subjected to long-term throughfall exclusion in the perhumid tropics
Authors: Schuldt B. , Leuschner C. , Horna V. , Moser G. , Köhler M. , Barus H.
Published: November 2010

Abstract. In a throughfall displacement experiment on Sulawesi, Indonesia, three 0.16 ha stands of a premontane perhumid rainforest were exposed to a two-year soil desiccation period that reduced the soil moisture in the upper soil layers beyond the conventional wilting point. About 25 variables, including leaf morphological and chemical traits, stem diameter growth and hydraulic properties of the xylem in the trunk and terminal twigs, were investigated in trees of the tall-growing tree species Castanopsis acuminatissima (Fagaceae) by comparing desiccated roof plots with nearby control plots. We tested the hypotheses that this tall and productive species is particularly sensitive to drought, and the exposed upper sun canopy is more affected than the shade canopy. Hydraulic conductivity in the xylem of terminal twigs normalised to vessel lumen area was reduced by 25%, leaf area-specific conductivity by 10–33% during the desiccation treatment. Surprisingly, the leaves present at the end of the drought treatment were significantly larger, but not smaller in the roof plots, though reduced in number (about 30% less leaves per unit of twig sapwood area), which points to a drought effect on the leaf bud formation while the remaining leaves may have profited from a surplus of water. Mean vessel diameter and axial conductivity in the outermost xylem of the trunk were significantly reduced and wood density increased, while annual stem diameter increment decreased by 26%. In contradiction to our hypotheses, (i) we found no signs of major damage to the C. acuminatissima trees nor to any other drought sensitivity of tall trees, and (ii) the exposed upper canopy was not more drought susceptible than the shade canopy.
Recent Developments in One‐Dimensional Inorganic Nanostructures for Photodetectors
Authors: Zhai Tianyou , Li Liang , Wang Xi , Fang Xiaosheng , Bando Yoshio , Golberg Dmitri
Published: November 2010

With large surface‐to‐volume ratios and Debye length comparable to their small sizes, one‐dimensional inorganic nanostructures have extensively been investigated and widely used to fabricate high‐performance nano­scale electronic and optoelectronic devices. This feature article reviews the state‐of‐the‐art research activities that focus on the one‐dimensional inorganic nanostructures and their photodetector applications. It begins with a survey of one‐dimensional inorganic nanostructures and the fundamentals of photodetectors. Some remarkable photoresponse characteristics are then presented, which are organized into sections covering several kinds of important nanostructures, such as ZnO, V2O5, ZnS, In2Se3, InSe, CdS, CdSe, ZnSe, Sb2Se3, ZrS2, Ag2S, and ZnxCd1‐xSe. Each section describes the corresponding photodetective properties in detail. Finally, the article concludes with some perspectives and outlook on the future developments in the field.
A Critical Look at Multilayered Polymer Capsules in Biomedicine: Drug Carriers, Artificial Organelles, and Cell Mimics
Authors: Städler Brigitte , Price Andrew D. , Zelikin Alexander N.
Published: November 2010

This Feature Article discusses utility of multilayered polymer capsules in biomedicine, specifically in drug delivery and in design of artificial organelles and cells. We provide a critical view on recent successes and identified shortcomings of these capsules in delivery of therapeutic cargo and outline plausible further developments of capsules as candidate drug carriers. A special emphasis is placed on poly(methacrylic acid) hydrogel capsules as successful carriers used in delivery of anticancer drugs and protein and peptide vaccines. We further present a novel biomedical approach whereby the same vessel acts first as a microreactor and then as a carrier for de novo synthesized therapeutic cargo. Finally, utility of polymer capsules in design of cell mimics is discussed with an emphasis on assembly and performance of capsosomes, polymer capsules with liposomal subcompartments. This presentation of capsules in biomedicine aims to provide an overview of past achievements and existing challenges associated with these candidate vessels and to stimulate further research interest from a broad scientific audience.
Ordered Materials for Organic Electronics and Photonics
Authors: O’Neill Mary , Kelly Stephen M.
Published: November 2010

We present a critical review of semiconducting/light emitting, liquid crystalline materials and their use in electronic and photonic devices such as transistors, photovoltaics, OLEDs and lasers. We report that annealing from the mesophase improves the order and packing of organic semiconductors to produce state‐of‐the‐art transistors. We discuss theoretical models which predict how charge transport and light emission is affected by the liquid crystalline phase. Organic photovoltaics and OLEDs require optimization of both charge transport and optical properties and we identify the various trade‐offs involved for ordered materials. We report the crosslinking of reactive mesogens to give pixellated full‐colour OLEDs and distributed bi‐layer photovoltaics. We show how the molecular organization inherent to the mesophase can control the polarization of light‐emitting devices and the gain in organic, thin‐film lasers and can also provide distributed feedback in chiral nematic mirrorless lasers. We update progress on the surface alignment of liquid crystalline semiconductors to obtain monodomain devices without defects or devices with spatially varying properties. Finally the significance of all of these developments is assessed.
ZnS Nanostructure Arrays: A Developing Material Star
Authors: Fang Xiaosheng , Wu Limin , Hu Linfeng
Published: November 2010

Semiconductor nanostructure arrays are of great scientific and technical interest because of the strong non‐linear and electro‐optic effects that occur due to carrier confinement in three dimensions. The use of such nanostructure arrays with tailored geometry, array density, and length‐diameter‐ratio as building blocks are expected to play a crucial role in future nanoscale devices. With the unique properties of a direct wide‐bandgap semiconductor, such as the presence of polar surfaces, excellent transport properties, good thermal stability, and high electronic mobility, ZnS nanostructure arrays has been a developing material star. The research on ZnS nanostructure arrays has seen remarkable progress over the last five years due to the unique properties and important potential applications of nanostructure arrays, which are summarized here. Firstly, a survey of various methods to the synthesis of ZnS nanostructure arrays will be introduced. Next recent efforts on exploiting the unique properties and applications of ZnS nanostructure arrays are discussed. Potential future directions of this research field are also highlighted.
Rett syndrome diagnostic criteria: Lessons from the Natural History Study
Authors: Percy Alan K. , Neul Jeffrey L. , Glaze Daniel G. , Motil Kathleen J. , Skinner Steven A. , Khwaja Omar , Lee Hye‐Seung , Lane Jane B. , Barrish Judy O , Annese Fran , McNair Lauren , Graham Joy , Barnes Katherine
Published: November 2010

Analysis of 819 participants enrolled in the Rett syndrome (RTT) Natural History Study validates recently revised diagnostic criteria. 765 females fulfilled 2002 consensus criteria for classic (653/85.4%) or variant (112/14.6%) RTT. All participants classified as classic RTT fulfilled each revised main criterion; supportive criteria were not uniformly present. All variant RTT participants met at least 3 of 6 main criteria in the 2002, 2 of 4 main criteria in the current format, and 5 of 11 supportive criteria in both. This analysis underscores the critical role of main criteria for classic RTT; variant RTT requires both main and supportive criteria. Ann Neurol 2010
Long‐term magnetic resonance imaging of stem cells in neonatal ischemic injury
Authors: Obenaus Andre , Dilmac Nejmi , Tone Beatriz , Tian Hou Rou , Hartman Richard , Digicaylioglu Murat , Snyder Evan Y. , Ashwal Stephen
Published: November 2010

Objective

Quantitative magnetic resonance imaging (MRI) can serially and noninvasively assess the degree of injury in rat pup models of hypoxic ischemic injury (HII). It can also noninvasively monitor stem cell migration following iron oxide prelabeling. Reports have shown that neural stem cells (NSCs) may help mediate neuroprotection or stimulate neuroreparative responses in adult and neonatal models of ischemic injury. We investigated the ability of high‐field MRI to monitor and noninvasively quantify the migration, proliferation, and location of iron oxide–labeled NSCs over very long time periods (58 weeks) in real time while contemporaneously correlating this activity with the evolving severity and extent of neural damage.

Methods

Labeled clonal murine NSCs (mNSCs) were implanted 3 days after unilateral HII in 10‐day‐old rat pups into the contralateral striatum or ventricle. We developed methods for objectively quantifying key aspects of dynamic NSC behavior (eg, viability; extent, and speed of migration; degree of proliferation; extent of integration into host parenchyma). MRI images were validated with histological and immunohistochemical assessments.

Results

mNSCs rapidly migrated (100 μm/day) to the lesion site. Chains of migrating NSCs were observed in the corpus callosum. In pups subjected to HII, though not in intact control animals, we observed a 273% increase in the MR‐derived volume of mNSCs 4 weeks after implantation (correlating with the known proliferative behavior of endogenous and exogenous NSCs) that slowly declined over the 58‐week time course, with no adverse consequences. Large numbers of now quiescent mNSCs remained at the site of injury, many retaining their iron oxide label.

Interpretation

Our studies demonstrate that MRI can simultaneously monitor evolving neonatal cerebral injury as well as NSC migration and location. Most importantly, it can noninvasively monitor proliferation dynamically for prolonged time periods. To be able to pursue clinical trials in newborns using stem cell therapies it is axiomatic that safety be insured through the long‐term real time monitoring of cell fate and activity, particularly with regard to observing unanticipated risks to the developing brain. This study supports the feasibility of reliably using MRI for this purpose.Ann Neurol 2011
γ‐Secretase component presenilin is important for microglia β‐amyloid clearance
Authors: Farfara Dorit , Trudler Dorit , Segev‐Amzaleg Niva , Galron Ronit , Stein Reuven , Frenkel Dan
Published: November 2010

Objective

The cleavage of amyloid precursor protein by γ‐secretase is an important aspect of the pathogenesis of Alzheimer's disease. γ‐Secretase also cleaves other membrane proteins (eg, Notch), which control cell development and homeostasis. Presenilin 1 and 2 are considered important determinants of the γ‐secretase catalytic site. Our aim was to investigate whether γ‐secretase can be important for microglial phagocytosis of Alzheimer's disease β‐amyloid.

Methods

We investigated the role of γ‐secretase in microglia activity toward β‐amyloid phagocytosis in cell culture using γ‐secretase inhibitors and small hairpin RNA and presenilin‐deficient mice.

Results

We found that γ‐secretase inhibitors impair microglial activity as measured in gene expression, protein levels, and migration ability, which resulted in a reduction of soluble β‐amyloid phagocytosis. Moreover, microglia deficient in presenilin 1 and 2 showed impairment in phagocytosis of soluble β‐amyloid. Dysfunction in the γ‐secretase catalytic site led to an impairment in clearing insoluble β‐amyloid from brain sections taken from an Alzheimer's disease mouse model when compared to microglia from wild‐type mice.

Interpretation

We suggest for the first time, a dual role for γ‐secretase in Alzheimer's disease. One role is the cleavage of the amyloid precursor protein for pathologic β‐amyloid production and the other is to regulate microglia activity that is important for clearing neurotoxic β‐amyloid deposits. Further studies of γ‐secretase‐mediated cellular pathways in microglia may provide useful insights into the development of Alzheimer's disease and other neurodegenerative diseases, providing future avenues for therapeutic intervention. ANN NEUROL 2010
JH biosynthesis by reproductive tissues and corpora allata in adult longhorned beetles, Apriona germari
Authors: Tian Ling , Ji Bao‐Zhong , Liu Shu‐Wen , He Chun‐Ling , Jin, Feng , Gao Jie , Stanley David , Li Sheng
Published: November 2010

We report on juvenile hormone (JH) biosynthesis from long‐chain intermediates by specific reproductive tissues and the corpora allata (CA) prepared from adult longhorned beetles, Apriona germari. The testes, male accessory glands (MAGs), ovaries, and CA contained the long‐chain intermediates in the JH biosynthetic pathway, farnesoic acid (FA), methyl farnesoate (MF), and JH III. The testes and ovaries, but not CA, produced radioactive JH III after the addition of 3H‐methionine and, separately, unlabeled methionine, to the incubation medium. We inferred that endogenous FA is methylated to MF in the testes and ovaries. Addition of farnesol led to increased amounts of FA in the testes, MAGs, ovaries, and CA, indicating oxidation of farnesol to FA. Addition of FA to incubation medium yielded increased JH III, again indicating methylation of FA to MF in the testes, MAGs, ovaries, but not CA. Addition of MF to incubation medium also led to JH III, from which we inferred the epoxidation of MF to JH III. JH biosynthesis from farnesol in the testes, MAGs, and ovaries of A. germari proceeds via oxidation to FA, methylation to MF, and epoxidation to JH III. This is a well‐known pathway to JH III, described here for the first time in reproductive tissues of longhorned beetles. © 2010 Wiley Periodicals, Inc.
Seismological challenges for stellar structure
Authors: Christensen‐Dalsgaard J.
Published: November 2010

Helioseismology has provided very detailed information about the solar interior, and extensive data on a large number of stars, although at less detail, are promised by the ongoing and upcoming asteroseismic projects. In the solar case there remain serious challenges in understanding the inferred solar structure, particularly in the light of the revised determinations of the solar surface composition. Also, a secure understanding of the origins of solar rotation as inferred from helioseismology, both in the radiative interior and in the convection zone, is still missing. In the stellar case challenges are certain to appear as the data allow more detailed inferences of the properties of stellar cores. Large remaining uncertainties in modelling concern the properties of convective cores and other processes that may cause mixing. As a result of developing asteroseismic signatures addressing these and other issues, we can look forward to a highly challenging, and hence exciting, era of stellar astrophysics (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The acoustic and magnetic solar cycle
Authors: Komm R.
Published: November 2010

The frequency variation of global modes provides information about the solar structure and the rotation rate of the solar interior. The solar‐cycle variation of the rotation rate, the so‐called torsional oscillation, extends throughout the convection zone. Alternating bands of faster‐ and slower‐than‐average rotation move from mid‐latitudes toward the equator during the solar cycle. The variation of the meridional flow, measured with local helioseismic techniques, is of similar amplitude. The zonal‐ and the meridional‐flow variation related to a new cycle are noticeable years before magnetic activity of the new cycle is present at the surface. The sound‐speed variations show a small, but significant variation with the solar cycle near the base of the convection zone, which might be interpreted as a change in magnetic field strength. The mode characteristics, such as acoustic radius and frequency shifts, provide information about changes in the near‐surface layers, where acoustic modes are excited (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Internal magnetic fields inferred from helioseismic data
Authors: Baldner C.S. , Antia H.M. , Basu S. , Larson T.P.
Published: November 2010

Measuring the internal solar magnetic fields and how they change over the course of a solar cycle is one of the key aims of helioseismology. We present the results of attempts to model the global mode splitting coefficients over solar cycle 23, assuming that the frequency splitting is only due to rotation and a large‐scale magnetic field. The first results using only the a2 coefficients show that the data are best fit by a combination of a poloidal field and a double‐peaked near‐surface toroidal field. The toroidal fields are centered at r0 = 0.999 R⊙ and r0 = 0.996 R⊙ and are confined to the near‐surface layers. The poloidal field is a dipole field. The peak strength of the poloidal field is 124 ± 17 G. The toroidal field peaks at 380 ± 30 G and 1.4 ± 0.2 kG for the shallower and deeper fields, respectively. The field strengths are highly correlated with surface activity. We also examine the differences between the minima at the beginning and the end of solar cycle 23 (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The interior of the Sun in 3‐D: Beyond the spherical Sun picture
Authors: Mathis S.
Published: November 2010

With all the results now obtained by global helioseismology, it is clear that we have to go beyond the classical spherical modelling of the Sun. In this way, it is now necessary to draw a picture that takes into account internal dynamical processes such as rotation, magnetic field, and waves from the core to the surface. This is a challenging task since such mechanisms involve length and time‐scales that differ from several orders of magnitude and impact on the solar behaviour both on dynamical and secular times. In this review, I will thus describe the present state of the art in the modelling of the internal dynamics of the Sun (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
What does the Sun suggest about global oscillation amplitudes in solar‐like stars
Authors: Severino G. , Straus Th. , Oliviero M. , Steffen M.
Published: November 2010

Motivated by the results of CoRoT and based on the solar experience, we develop a new stellar scaling law for the intensity‐velocity amplitude ratio (gain) of resonant oscillations, which is a quantity independent of the excitation model. The comparison of our approach with observations gives new interesting results for the Sun as a star. Moreover, for a sample of three solar‐like stars observed by CoRoT, we found that our scaling law provides an explanation of the low observed luminosity amplitudes which is an alternative to non‐adiabatic effects (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local helioseismology and the active Sun
Authors: Schunker H.
Published: November 2010

The goal of local helioseismology is to elicit three‐dimensional information about the sub‐surface (or far‐side) structure and dynamics of the Sun from observations of the helioseismic wave field at the surface. The physical quantities of interest include flows, sound‐speed deviations and magnetic fields. However, strong surface magnetic fields induce large perturbations to the waves making inversions difficult to interpret. The purpose of this paper is to outline the methods of analysis used in local helioseismology, review discoveries associated with the magnetic Sun made using local helioseismology from the past three years, and highlight the efforts towards imaging the interior in the presence of strong magnetic fields (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new code for Fourier‐Legendre analysis of large datasets: First results and a comparison with ring‐diagram analysis
Authors: Doerr H.‐P. , Roth M. , Zaatri A. , Krieger L. , Thompson M. J.
Published: November 2010

Fourier‐Legendre decomposition (FLD) of solar Doppler imaging data is a promising method to estimate the sub‐surface solar meridional flow. FLD is sensible to low‐degree oscillation modes and thus has the potential to probe the deep meridional flow. We present a newly developed code to be used for large scale FLD analysis of helioseismic data as provided by the Global Oscillation Network Group (GONG), the Michelson Doppler Imager (MDI) instrument, and the upcoming Helioseismic and Magnetic Imager (HMI) instrument. First results obtained with the new code are qualitatively comparable to those obtained from ring‐diagram analyis of the same time series (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observational results from active region seismology
Authors: Gonzälez Hernández I.
Published: November 2010

Active regions are one of the most observed features in the solar surface. High‐resolution solar telescopes on ground and space have revealed the fine configuration of umbra and penumbra of sunspots with amazing detail. However, the subsurface structure of sunspots and active regions remains, for the most part, unknown. Thanks to the development of local helioseismology methods, the properties of active regions under the solar surface are starting to unravel. This paper reviews some of the main results obtained from the application of local helioseismology techniques to the study of the subsurface dynamics and magnetic properties of active regions (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constraints on the core µ ‐gradient of the solar‐like star HD 49385 via low‐degree mixed modes
Authors: Deheuvels S. , Michel E.
Published: November 2010

The existence of an ℓ = 1 avoided crossing in the spectrum of the solar‐like pulsator CoRoT*‐target HD 49385 (*The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES with participation of the Science Programs of ESA; ESA's RSSD, Austria, Belgium, Brazil, Germany, and Spain.) was established by Deheuvels & Michel (2009). It is the first confirmed detection of such a phenomenon. The authors showed in a preliminary modeling of the star that it was in a post main sequence status. Being a 1.3 M⊙ ‐star, HD 49385 has had a convective core during its main sequence phase. The µ ‐gradient left by the withdrawal of this core bears information about the processes of transport at the boundary of the core. We here investigate the constraints that the observed avoided crossing brings on the µ ‐gradient in the core of the star (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An alternative to mode fitting
Authors: Mosser B.
Published: November 2010

The space mission CoRoT provides us with a large amount of high‐duty cycle long‐duration observations. Mode fitting has proven to be efficient for the complete and detailed analysis of the oscillation pattern, but remains time consuming. Furthermore, the photometric background due to granulation severely complicates the analysis. Therefore, we attempt to provide an alternative to mode fitting, for the determination of large separations. With the envelope autocorrelation function and a dedicated filter, it is possible to measure the variation of the large separation independently for the ridges with even and odd degrees. The method appears to be as accurate as the mode fitting. It can be very easily implemented and is very rapid (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectrum analysis and seismic interpretation of a solar‐like pulsator (HD 49933) observed by CoRoT
Authors: Benomar O. , Baudin F. , Marques J.P. , Goupil M.J. , Lebreton Y. , Deheuvels S.
Published: November 2010

The star HD 49933 has been observed by the mission CoRoT two times (for 60 and 137 days). Its spectrum shows a wealth of oscillation modes but was found difficult to analyse. In the following, we summarize why it was so, and then present a modeling of the star using seismic constraints and show the effect of the microscopic diffusion and of the overshoot in the modeling. We conclude that some convective overshoot from the core is needed while it is difficult to give a definitive conclusion concerning the effect of the microscopic diffusion on the modeling of HD 49933 (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Can asteroseismology solve the solar abundance problem? The test case of HD 43587
Authors: Mazumdar A. , Singhal L. , Prabhu S.
Published: November 2010

The recent downward revision of solar abundances has serious implications not only for the Sun, but for distant stars as well. The effects of altering the mixture of elements inside a star and lowering the overall metallicity on stellar oscillation frequencies are tested on theoretical models of a CoRoT primary target star, HD 43587. It is found that although frequency separations are significantly affected by changes in the chemical makeup, it might still be difficult to distinguish between the two cases of solar abundances because of the ambiguity in the fundamental parameters, such as effective temperature, luminosity, and [Fe/H] of the target star (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Kepler Asteroseismic Investigation: Scientific goals and first results
Authors: Kjeldsen H. , Christensen‐Dalsgaard J. , Handberg R. , Brown T.M. , Gilliland R.L. , Borucki W.J. , Koch D.
Published: November 2010

Kepler is a NASA mission designed to detect exoplanets and characterize the properties of exoplanetary systems. Kepler also includes an asteroseismic programme which is being conducted through the Kepler Asteroseismic Science Consortium (KASC), whose 400 members are organized into 13 working groups by type of variable star. So far data have been available from the first 7 month of the mission containing a total of 2937 targets observed at a 1‐min cadence for periods between 10 days and 7 months. The goals of the asteroseismic part of the Kepler project is to perform detailed studies of stellar interiors. The first results of the asteroseismic analysis are orders of magnitude better than seen before, and this bodes well for how the future analysis of Kepler data for many types of stars will impact our general understanding of stellar structure and evolution (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asteroseismology of solar‐type stars with Kepler I: Data analysis
Authors: Karoff C. , Chaplin W.J. , Appourchaux T. , Elsworth Y. , Garcia R.A. , Houdek G. , Metcalfe T.S. , Molenda‐Żakowicz J. , Monteiro M.J.P.F.G. , Thompson M.J. , Christensen‐Dalsgaard J. , Gilliland R.L. , Kjeldsen H. , Basu S. , Bedding T.R. , Campante T.L. , Eggenberger P. , Fletcher S.T. , Gaulme P. , Handberg R. , Hekker S. , Martic M. , Mathur S. , Mosser B. , Regulo C. , Roxburgh I.W. , Salabert D. , Stello D. , Verner G.A , Belkacem K. , Biazzo K. , Cunha M.S. , Gruberbauer M. , Guzik J.A. , Kupka F. , Leroy B. , Ludwig H.‐G. , Mathis S. , Noels A. , Noyes R.W. , Roca Cortes T. , Roth M. , Sato K.H. , Schmitt J. , Suran M.D. , Trampedach R. , Uytterhoeven K. , Ventura R. , Wilson P.A.
Published: November 2010

We report on the first asteroseismic analysis of solar‐type stars observed by Kepler. Observations of three G‐type stars, made at one‐minute cadence during the first 33.5 days of science operations, reveal high signal‐to‐noise solar‐like oscillation spectra in all three stars: About 20 modes of oscillation can clearly be distinguished in each star. We discuss the appearance of the oscillation spectra, including the presence of a possible signature of faculae, and the presence of mixed modes in one of the three stars (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solar‐like oscillations in cluster stars
Authors: Stello D. , Basu S. , Bedding T.R. , Brogaard K. , Bruntt H. , Chaplin W.J. , Christensen‐Dalsgaard J. , Demarque P. , Elsworth Y.P. , García R.A. , Gilliland R.L. , Hekker S. , Huber D. , Karoff C. , Kjeldsen H. , Lebreton Y. , Mathur S. , Meibom S. , Molenda‐Żakowicz J. , Noels A. , Roxburgh I.W. , Aguirre V.S. , Sterken C. , Szabö R.
Published: November 2010

We present a brief overview of the history of attempts to obtain a clear detection of solar‐like oscillations in cluster stars, and discuss the results on the first clear detection, which was made by the Kepler Asteroseismic Science Consortium (KASC) Working Group 2 (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)