bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate and vegetation history of western Portugal inferred from Albian near-shore deposits (Galé Formation, Lusitanian Basin)
Authors: HEIMHOFER ULRICH , HOCHULI PETER-A. , BURLA STEFAN , OBERLI FELIX , ADATTE THIERRY , DINIS JORGE L. , WEISSERT HELMUT
Published: May 2012

The late Early Cretaceous greenhouse climate has been studied intensively based on proxy data derived essentially from open marine archives. In contrast, information on continental climatic conditions and on the accompanying response of vegetation is relatively scarce, most notably owing to the stratigraphic uncertainties associated with many Lower Cretaceous terrestrial deposits. Here, we present a palynological record from Albian near-shore deposits of the Lusitanian Basin of W Portugal, which have been independently dated using Sr-isotope signals derived from low-Mg oyster shell calcite.87Sr/86Sr values fluctuate between 0.707373 ± 0.00002 and 0.707456 ± 0.00003; absolute values and the overall stratigraphic trend match well with the global open marine seawater signature during Albian times. Based on the new Sr-isotope data, existing biostratigraphic assignments of the succession are corroborated and partly revised. Spore-pollen data provide information on the vegetation community structure and are flanked by sedimentological and clay mineralogical data used to infer the overall climatic conditions prevailing on the adjacent continent. Variations in the distribution of climate-sensitive pollen and spores indicate distinct changes in moisture availability across the studied succession with a pronounced increase in hygrophilous spores in late Early Albian times. Comparison with time-equivalent palynofloras from the Algarve Basin of southern Portugal shows pronounced differences in the xerophyte/hygrophyte ratio, interpreted to reflect the effect of a broad arid climate belt covering southern and southeastern Iberia during Early Albian times.
Primary peak and chronic malaria infection levels are correlated in experimentally infected great reed warblers
Authors: ASGHAR MUHAMMAD , WESTERDAHL HELENA , ZEHTINDJIEV PAVEL , ILIEVA MIHAELA , HASSELQUIST DENNIS , BENSCH STAFFAN
Published: May 2012

Malaria parasites often manage to maintain an infection for several months or years in their vertebrate hosts. In humans, rodents and birds, most of the fitness costs associated with malaria infections are in the short initial primary (high parasitaemia) phase of the infection, whereas the chronic phase (low parasitaemia) is more benign to the host. In wild birds, malaria parasites have mainly been studied during the chronic phase of the infection. This is because the initial primary phase of infection is short in duration and infected birds with severe disease symptoms tend to hide in sheltered places and are thus rarely caught and sampled. We therefore wanted to investigate the relationship between the parasitaemia during the primary and chronic phases of the infection using an experimental infection approach. We found a significant positive correlation between parasitaemia in the primary peak and the subsequent chronic phase of infection when we experimentally infected great reed warblers (Acrocephalus arundinaceus) withPlasmodium ashfordi. The reason for this association remains to be understood, but might arise from individual variation in exoerythrocytic parasite reservoirs in hosts, parasite antigenic diversity and/or host genetics. Our results suggest that the chronic phase parasitaemia can be used to qualitatively infer the parasitaemia of the preceding and more severe primary phase, which is a very important finding for studies of avian malaria in wild populations.
Mixed life-history strategies in a local population of the ectoparasitic flyCarnus hemapterus
Authors: AMAT-VALERO M. , VÁCLAV R. , MARTÍNEZ T. , VALERA F.
Published: May 2012

A major issue for the proper understanding of the evolution of life-cycle histories is the regulation of voltinism and its variation. Diapause characteristics are known to regulate voltinism, but the underlying mechanisms are poorly understood. This paper studies diapause duration and voltinism variation in a haematophagous diptera parasitizing 2 sympatric hosts with very different breeding phenologies. We hypothesize that bivoltinism will be more frequent in carnid flies parasitizing an early breeding, multi-brooded species than in flies parasitizing a late breeder, single-brooded species. We obtained evidence of the co-occurrence of uni- and bivoltinism in both clutches of the multi-brooded Spotless starling (Sturnus unicolor) as well as in clutches of the single-brooded European roller (Coracias garrulus). Unexpectedly, the proportion of bivoltine flies was similar in both host species. A remarkable degree of host-parasite synchronization at the population level was found for bivoltine flies. Our findings reveal the facultative nature of diapause inCarnus. We discuss the influence of abiotic conditions and host availability on polymorphism in life-history cycles and the consequences both for the parasite and the host.
Life cycles, molecular phylogeny and historical biogeography of the ‘pygmaeus’ microphallids (Digenea: Microphallidae): widespread parasites of marine and coastal birds in the Holarctic
Authors: GALAKTIONOV KIRILL V. , BLASCO-COSTA ISABEL , OLSON PETER D.
Published: May 2012

The ‘pygmaeus’ microphallids (MPG) are a closely related group of 6 digenean (Platyhelminthes: Trematoda) Microphallus species that share a derived 2-host life cycle in which metacercariae develop inside daughter sporocysts in the intermediate host (intertidal and subtidal gastropods, mostly of the genus Littorina) and are infective to marine birds (ducks, gulls and waders). Here we investigate MPG transmission patterns in coastal ecosystems and their diversification with respect to historical events, host switching and host-parasite co-evolution. Species phylogenies and phylogeographical reconstructions are estimated on the basis of 28S, ITS1 and ITS2 rDNA data and we use a combination of analyses to test the robustness and stability of the results, and the likelihood of alternative biogeographical scenarios. Results demonstrate that speciation within the MPG was not associated with co-speciation with either the first intermediate or final hosts, but rather by host-switching events coincident with glacial cycles in the Northern Hemisphere during the late Pliocene/Pleistocene. These resulted in the expansion of Pacific biota into the Arctic-North Atlantic and periodic isolation of Atlantic and Pacific populations. Thus we hypothesize that contemporary species of MPG and their host associations resulted from fragmentation of populations in regional refugia during stadials, and their subsequent range expansion from refugial centres during interstadials.
Effects of Appraisals of Anomalous Experience on Distress in People at Risk of Psychosis
Authors: Taylor Hannah E. , Parker Sophie , Mansell Warren , Morrison Anthony P.
Published: May 2012

Background: A cognitive model of psychosis suggests that appraisals of psychotic-like experiences (PLEs), and the subsequent responses adopted, are responsible for the maintenance of distress and disability associated with psychosis. Aims: This study aimed to investigate whether it is possible to manipulate appraisals of an anomalous experience in people at risk of psychosis and whether this affects levels of distress. Method: Participants who had experienced an “at risk mental state” (ARMS) within the past year, were randomized to one of two groups and received either negative or neutral information pertaining to an anomalous experience (a card trick). Participants completed a questionnaire measuring PLEs, then completed pre and post measures of distress and anxiety in relation to the card trick. Participants were also asked to rate a series of psychotic or non-psychotic appraisals regarding how they thought the card trick worked. Results: Data analysis revealed that distress and anxiety were not related to the information group assigned (our experimental manipulation was unsuccessful). However, when analyzed as one group, higher conviction in non-psychotic appraisals was found to be related to lower levels of distress and state anxiety. Conclusions: The findings provide some validation for a relationship between appraisals and distress. Clinical implications, methodological limitations and possible future research directions are discussed.
Introduction to the Special Issue: Japanese Studies in Japan and its Vicinities: Economics and Sociology
Authors: INOGUCHI TAKASHI
Published: May 2012

Studies of foreign countries often depend on the lure of the image of an unknown market. The lure of the China market led King George III to send his emissary, Lord MacCartney, to China to meet Emperor Jianlung in 1793 and to give the Emperor a letter as well as an enormous collection of gifts. The purpose of this envoy to China was to convince the Emperor to ease restrictions on trade between Great Britain and China. In 1816, in the chronicles of Emperor Jiaqing, foreign countries were categorized in two ways: tributary countries and trading countries. By tributary country is meant a country, usually a smaller and less-advanced country, which pays loyal respect and is compliant and in return is given many rare and precious gifts, and is thus bestowed a position in what is considered as the Pax Sinica (Latin for Chinese Peace). By trading country is meant a country which is devoid of the meaning in the Pax Sinica in Chinese understanding. England was categorized as a tributary country, whereas in English history England was portrayed as one of the Western countries which tried to open the country and ports, thereby expanding its commercial ties. According to the Jiaqing huidian (imperial chronicles) England, Korea, and Vietnam are categorized as tributary countries, whereas France, the Netherlands, and Japan are categorized as a trading countries. During most of the Qing period (1644–1911), Japan adopted the system of trading with foreign countries whereby the Tokugawa central government monopolized external commerce, which traded only with Dutch and Chinese merchants. In 1949, the People's Republic of China was proclaimed to change the content of history. Instead of tributary-networked Pax Sinica, Western and later Japanese imperialism and colonialism started the destruction of the Pax Sinica which was replaced by Western hegemony spearheaded by England.
Shifting Domestic and International Perceptions of Japan's Economy
Authors: NOGUCHI ASAHI
Published: May 2012

Japan's remarkable economic success especially from the 1960s to the 1980s has attracted extensive worldwide attention. However, the world's admiration has plummeted since the 1990s, when the Bubble Economy burst, bringing on chronic stagnation. Since then, the world has regarded the Japanese economy less as a desirable model and more as an evident failure with many lessons for other economies. These external judgments, positive and negative, have also affected how the Japanese perceive their own economy. This article reviews how these domestic and international perceptions of Japan's economy have varied. It situates the companion articles by Hwang (2012) and Harada (2012) in the historical context of studies of the Japanese economy. This article especially discusses one recurring fixation that muddles comprehension of factors underpinning Japan's economic success and failure: the tendency to overestimate characteristics that supposedly are specific to Japan and different from other market-oriented economies. From the 1960s through the 1980s, scholars, commentators, policy-makers, and the public insisted these characteristics were singular and significant contributors to Japan's remarkable economic development. Since the 1990s, they have considered them the root causes of Japan's remarkable stagnation. Both are exaggerations. Although some singularly Japanese attributes perhaps contributed to Japan's economic ascent and decline, it is equally plausible they did not. It is more likely that poorly conceived and executed macroeconomic policies, especially monetary policy, had greater influence on Japan's post-1990s stagnation.
Large volumes of rejuvenated volcanism in Samoa: Evidence supporting a tectonic influence on late‐stage volcanism
Authors: Konter Jasper G. , Jackson Matthew G.
Published: May 2012

Hot spot volcanoes are commonly constructed in a characteristic sequence of stages. After the volumetrically dominant shield stage, a protracted period of quiescence ends with a final stage of activity: rejuvenated volcanism. The mechanism responsible for generating rejuvenated volcanism is not generally agreed upon. New data obtained for samples 200 m down‐section in a deeply incised canyon on Savai‘i (Samoa) are unusually enriched isotopically and indicate a relatively voluminous rejuvenated stage compared to other intraplate volcanoes. Using a modified flexural model originally proposed for Hawai‘i, we suggest that the location of Samoa near the Tonga Trench terminus causes plate flexure resulting in upward flow of the shallow mantle driving partial melting. In particular, subduction‐related plate bending in the Samoan region may cause a larger flexural amplitude than generated by volcanic loading in Hawai‘i. The larger amplitude may explain the larger volume of rejuvenated melt in Samoa, constrained by our new data. Moreover, we argue that Sr‐Nd‐Pb‐Os‐He‐Ne isotopes in Samoan rejuvenated lavas are all consistent with sampling of a lithospheric component that is characterized by a metasomatic imprint from the Pacific Plate's earlier passage over the Rarotonga hot spot. Furthermore, temperature estimates for the melts suggest a drop in temperature during the predicted shallower melting due to flexural uplift, compared to the conditions during shield volcanism. Thus, flexural bending and metasomatism of the Samoan lithosphere may have generated the voluminous and geochemically distinct Samoan rejuvenated lavas, implying the lithosphere may play an important role during this stage in non‐ Hawaiian hot spots.
Radio occultation measurement of the electron density near the lunar surface using a subsatellite on the SELENE mission
Authors: Imamura T. , Nabatov A. , Mochizuki N. , Iwata T. , Hanada H. , Matsumoto K. , Noda H. , Kono Y. , Liu Q. , Futaana Y. , Ando H. , Yamamoto Z. , Oyama K.‐I. , Saito A.
Published: May 2012

The electron density distribution in the vicinity of the lunar surface was explored with the radio occultation technique using a subsatellite on the SELENE mission. Although the measurements suffer from contamination by the terrestrial ionosphere and interplanetary plasma, an analysis of more than 300 measurements provides adequate statistics and reveals a general trend. The result suggests that a dense ionosphere covering the whole sunlit side, as suggested by the radio occultation measurements on the Soviet Luna 19 and 22 missions, does not exist. However, weak signatures of electron density enhancement with densities on the order of 100 cm−3 are observed below 30 km altitude at solar zenith angles less than 60°. The statistically averaged density reaches a peak at around 15 km altitude and decreases gradually at higher altitudes and toward the surface. Although the suggested electron layer is thinner and less extended horizontally than that reported by Luna 19 and 22, the existence of such an ionized layer is still difficult to explain by conventional ionosphere generation mechanisms. An alternative source of electrons may be required.
Shallow creep on the Haiyuan Fault (Gansu, China) revealed by SAR Interferometry
Authors: Jolivet R. , Lasserre C. , Doin M.‐P. , Guillaso S. , Peltzer G. , Dailu R. , Sun J. , Shen Z.‐K. , Xu X.
Published: May 2012

Interferometric synthetic aperture radar data are used to map the interseismic velocity field along the Haiyuan fault system (HFS), at the north‐eastern boundary of the Tibetan plateau. Two M ∼ 8 earthquakes ruptured the HFS in 1920 and 1927, but its 260 km‐long central section, known as the Tianzhu seismic gap, remains unbroken since ∼1000 years. The Envisat SAR data, spanning the 2003–2009 period, cover about 200 × 300 km2 along three descending and two ascending tracks. Interferograms are processed using an adapted version of ROI_PAC. The signal due to stratified atmospheric phase delay is empirically corrected together with orbital residuals. Mean line‐of‐sight velocity maps are computed using a constrained time series analysis after selection of interferograms with low atmospheric noise. These maps show a dominant left‐lateral motion across the HFS, and reveal a narrow, 35 km‐long zone of high velocity gradient across the fault in between the Tianzhu gap and the 1920 rupture. We model the observed velocity field using a discretized fault creeping at shallow depth and a least squares inversion. The inferred shallow slip rate distribution reveals aseismic slip in between two fully locked segments. The average creep rate is ∼5 mm yr−1, comparable in magnitude with the estimated loading rate at depth, suggesting no strain accumulation on this segment. The modeled creep rate locally exceeds the long term rate, reaching 8 mm yr−1, suggesting transient creep episodes. The present study emphasizes the need for continuous monitoring of the surface velocity in the vicinity of major seismic gaps in terms of seismic hazard assessment.
Reconciling Cretaceous paleomagnetic and marine magnetic data for Iberia: New Iberian paleomagnetic poles
Authors: Neres M. , Font E. , Miranda J. M. , Camps P. , Terrinha P. , Mirão J.
Published: May 2012

The Cretaceous paleogeography and the kinematic evolution of the Iberian plate are poorly constrained. Especially problematic is to reconcile Iberian paleomagnetic data with paleomagnetic data of the neighboring plates and with Euler poles derived from seafloor magnetic anomalies. The first limitation arises from the Cretaceous Normal Polarity Superchron where paleogeographic reconstruction using marine magnetic anomalies is handicapped. The second arises from the paucity of reliable paleomagnetic poles with satisfactory statistical criteria and age. In order to address these shortcomings and provide new high quality paleomagnetic poles for Iberia, we conducted a detailed rock magnetic and paleomagnetic study of two Cretaceous magmatic sills, the Paço de Ilhas (PI) and Foz da Fonte (FF) sills, from the Lusitanian Basin, Portugal, recently dated at about 88 and 94 Ma, respectively. Our results show that the magnetic mineralogy of the sills is primary, i.e., acquired during magma cooling, and essentially represented by titanomagnetite. The corresponding paleomagnetic poles match the synthetic APWP from the African plate at 80 and 100 Ma. On the basis of a rigorous selection of Iberian Cretaceous poles, we then calculated mean paleomagnetic poles for different time intervals and found that Iberian paleomagnetic data fit well the global APWP between 70 and 120 Ma, but move far away from the APWP at pre‐rift times. Our approach shows that new and better constrained paleomagnetic poles can aide in solving part of the contradiction between Iberian and African APWPs.
Revealing highly complex elastic nonlinear (anelastic) behavior of Earth materials applying a new probe: Dynamic acoustoelastic testing
Authors: Renaud G. , Le Bas P.‐Y. , Johnson P. A.
Published: May 2012

Recent work in medical nonlinear acoustics has led to the development of refined experimental method to measure material elastic nonlinear (anelastic) response. The technique, termed dynamic acoustoelastic testing, has significant implications for the development of a physics‐based theory because it provides information that existing methods cannot. It provides the means to dynamically study the velocity‐strain and attenuation‐strain relations through the full wave cycle in contrast to most methods that measure average response. The method relies on vibrating a sample at low frequency in order to cycle it through different levels of stress‐strain. Simultaneously, an ultrasonic source applies pulses and the change in wave speed and attenuation as a function of the low frequency strain is measured. We report preliminary results in eleven room‐dry rock samples. In crystalline rock, we expect that the elastic nonlinearity arises from the microcracks and dislocations contained within individual crystals. In contrast, sedimentary rocks may have other origins of elastic nonlinearity, currently under debate. A large quadratic elastic nonlinearity is observed in Berkeley blue granite, presumably due to microcracks and dislocation‐point defect interactions. In sedimentary rocks that include limestones and sandstones we observe behaviors that can differ markedly from the granite, potentially indicating different mechanical mechanisms. We further observe changes in measured nonlinear coefficients that are wave‐strain amplitude dependent. Ultimately we hope that the new approach will provide the means to quantitatively relate material nonlinear elastic behavior to the responsible features, that include soft bonds dislocations, microcracks, and the modulating influences of water content, temperature and pressure.
Flow fields around the Emperor Seamounts detected from current data
Authors: Wagawa Taku , Yoshikawa Yutaka , Isoda Yutaka , Oka Eitarou , Uehara Kazuyuki , Nakano Toshiya , Kuma Kenshi , Takagi Shogo
Published: May 2012

Bathymetric influences of the Emperor Seamounts (ESs) on the local and large‐scale flow fields in the subarctic North Pacific were investigated by analyzing data of directly measured velocity obtained using Argo floats, near‐surface buoys, and moored current meters. The local influences were evident in notable deflections of two relatively strong (∼0.05 m s−1) eastward flows over ESs. A Taylor cap induced by the eastward flow impinging against the Nintoku Seamount (around 42.0°N, 170.5°E) was clearly identified in the climatological flow field at 1000 m depth. This flow pattern was also identified in the near‐surface flow field (15 m depth) and dynamic height field at 200 dbar relative to 2000 dbar, indicating the Taylor cap is stable or frequently generated and extends to the surface. An anticyclonic flow was found over the Suiko Seamount (around 45.0°N, 170.5°E). The influences on the large‐scale flow field were found in data obtained from current meters moored over the southeastern flank of the Suiko Seamount and Argo float trajectories. These data indicate for the first time from velocity observations that there is a seasonally varying boundary current along the eastern side of ESs partially compensating for the Sverdrup transport to the east of ESs, and hence, the seasonally varying component of the subarctic gyre in the North Pacific is divided into two subgyres by ESs.
Quantifying trends in surface roughness and the effect on surface wind speed observations
Authors: Wever N.
Published: May 2012

Many studies analyzing surface wind speed observations find a decrease in wind speed over the last 30 to 50 years. A cause sometimes proposed is increasing surface roughness, although to date the evidence that this is the primary factor is still inconclusive. In this study, changes in surface roughness are investigated for 20 stations in the Netherlands and 137 stations in 7 other European countries. From the Dutch data set, local aerodynamic roughness lengths were calculated from hourly gust factors. Trends in wind speed for individual stations and wind direction sectors correlate negatively with trends in surface roughness. For 1962–2009, typically a doubling of the local roughness length was found, with the strongest increase after 1981. An accompanying average decrease in wind speed by 3.1% (0.13 m/s) per decade was found for 1981–2009. A conceptual boundary layer model was used to show that 70% of the wind speed trend can be attributed to surface roughness changes; the remaining 30% of the trend remains unresolved. Changes in land use, including urbanization, forestation, and a decrease in pasture land area, are probable causes for the increasing surface roughness. For the European station data from the European Climate Assessment and Dataset (ECA&D) and the Swiss Federal Office of Meteorology and Climatology (MeteoSwiss), the analysis was restricted to daily gust factors. Observed trends in wind speed at stations correlate negatively with trends in gust factors. Averaged over all stations, the wind speed decreased 1.2% (0.05 m/s) per decade over 1982–2009, consistent with increasing surface roughness.
An innovative physical scheme to retrieve simultaneously surface temperature and emissivities using high spectral infrared observations from IASI
Authors: Paul M. , Aires F. , Prigent C. , Trigo I. F. , Bernardo F.
Published: May 2012

Retrieving atmospheric temperature and water vapor profiles from infrared satellite observations over continental surfaces is a complex problem because of the heterogeneity of land surfaces and the difficulty of modeling their interaction with the radiation. This results in the surface‐sensitive observations from sounding instruments over land usually not being assimilated into numerical prediction systems at meteorological operational centers. Correct characterization of the interaction between the atmosphere and the surface would allow considering the information contained in those channels. This requires accurate estimates of the surface emissivities at the spectral resolution of recent instruments such as Infrared Atmospheric Sounding Interferometer (IASI) or Atmospheric Infrared Sounder (AIRS). An emissivity interpolator is developed in this study to estimate the land surface emissivities at a high spectral resolution compatible with IASI or AIRS instrument channels. It is based on Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved emissivities. This surface emissivity is used as a first guess in an innovative surface parameter inversion scheme that simultaneously retrieves the surface emissivity and temperature. Radiative transfer calculations with the resulting surface information show a significantly better agreement with the observations (root mean square error of 1.7 K on average over bands 1 and 2 of the IASI spectrum), as compared to calculations using the first guess information (root mean square error of 3.5 K). The retrieved surface skin temperatures are compared to the Land Surface Analysis Satellite Applications Facility (LSA SAF) estimates derived from Spinning Enhanced Visible and Infrared Imager (SEVIRI) measurements, and the root mean square difference is below 2 K.
Stochastic decadal climate simulations for the Berg and Breede Water Management Areas, Western Cape province, South Africa
Authors: Greene Arthur M. , Hellmuth Molly , Lumsden Trevor
Published: May 2012

A method is described for the generation of multivariate stochastic climate sequences for the Berg and Breede Water Management Areas in the Western Cape province of South Africa. The sequences, based on joint modeling of precipitation and minimum and maximum daily temperatures, are conditioned on annualized data, the aim being to simulate realistic variability on annual to decadal time scales. A vector autoregressive (VAR) model is utilized for this purpose and reproduces well those statistical attributes, including intervariable correlation and serial autocorrelation in individual variables, most relevant for the regional climate in this setting. The sequences incorporate nonlinear climate change trends, inferred using an ensemble of global climate models from the Coupled Model Intercomparison Project (CMIP5). Subannual variability is simulated using a block resampling scheme based on the k‐nearest‐neighbor approach, preserving both temporal patterns and spatial correlations. Downscaling to a network of quinary‐level catchments enables distributed runoff, streamflow, and crop simulations and the assessment and integration of impacts. Final output takes the form of daily sequences, structured for driving the ACRU agrohydrological model of the University of KwaZulu‐Natal, South Africa.
On the effect of dust aerosols on AIRS and IASI operational level 2 products
Authors: Maddy E. S. , DeSouza‐Machado S. G. , Nalli N. R. , Barnet C. D. , L Strow L. , Wolf W. W. , Xie H. , Gambacorta A. , King T. S. , Joseph E. , Morris V. , Hannon S. E. , Schou P.
Published: May 2012

Satellite retrievals of environmental parameters can enable a global scale understanding of various atmospheric phenomena. Validation of these retrievals using in situ and other correlative measurements is critical to the success of our accurate interpretation of such phenomena. In this paper, we analyze the effect of dust on AIRS and IASI operational level 2 profiles using data obtained from the 2009–2011 AEROSE campaigns. We find that the presence of dust in the AIRS and IASI measurements biases the cloud‐cleared radiances by as much as 4 K. In addition, we find that the temperature and surface temperature retrievals resultant from these cloud‐cleared radiances show 2 to 3 K spurious oscillations throughout the troposphere.
The morphology of Saturn's ultraviolet aurora
Authors: Carbary J. F.
Published: May 2012

Spectrographic images in the far ultraviolet, obtained from observations made from 2007 to 2009, are used to quantify and compare the morphology of Saturn's northern and southern aurora in local time. Made by the UVIS imager on the Cassini spacecraft, these observations differ from previous UV observations of Saturn's aurora by offering complete local time coverage of the aurora from small zenith angles. A statistical picture emerges after combining over 105 spectrographic images of the north and south aurora. From its composite, the northern aurora exhibits an intensity peak of ∼40 kR near 05 h local time, while the southern aurora peaks at ∼60 kR near the same local time. Aurora intensities in the post‐noon sectors are essentially constant at ∼10 kR. The half‐power points of latitudinal profiles reveal widths of ∼4° near dawn and ∼8° near dusk in both north and south. The aurora has an approximately circular shape (not oval!), although harmonic fits suggest the northern aurora is more nearly circular than the southern. The center of the northern aurora has an offset of ∼1–2° from the pole, while the southern center is offset by ∼2–3°, with both offsets in the midnight‐to‐dawn quadrant. When mapped to the polar regions, precipitation of field‐aligned energetic electrons (>20 keV) generally lies equatorward of the main auroral intensity at all local times.
The local amplification of surface waves: A new observable to constrain elastic velocities, density, and anelastic attenuation
Authors: Lin Fan‐Chi , Tsai Victor C. , Ritzwoller Michael H.
Published: May 2012

The deployment of USArray across the continental U.S. has prompted developments within surface wave tomography to exploit this unprecedented data set. Here, we present a method to measure a new surface wave observable: broadband surface wave amplification that provides new and unique constraints on elastic velocities and density within the crust and upper mantle. The method, similar to its phase velocity counterpart referred to as Helmholtz tomography, initiates by constructing phase travel time and amplitude maps across the array for each period and earthquake. Spatial differential operators are then applied to evaluate the amplitude variation, as well as the effect of focusing/defocusing. Based on the 2‐D damped wave equation, the amplitude variation corrected for focusing/defocusing is linked directly to both local amplification and intrinsic attenuation, which are separated by examining waves propagating in opposite directions. We apply the method to teleseismic Rayleigh waves observed across USArray between periods of 24 and 100 s and show that the observed amplification maps are strongly correlated with known geological features. Small‐scale attenuation measurements are contaminated by wavefield complexities, but larger‐scale anelastic attenuation is estimated reliably. The observed amplification maps compare well with predictions based on recent 3‐D shear velocity models of the western U.S. that were produced from ambient noise and earthquake data. Notably, predictions based on models with different prescribed density structures demonstrate the potential for using estimates of local amplification to constrain not only 3‐D velocity structure but also density.
Don't ask, don't tell, don't publish
Authors: Jacobs Howy
Published: May 2012

Howy's editorial to accompany the launch of EMBO reports focus series on Sex and Molecular Biology asks whatever happened to the ‘gay gene’.
Occult infection with hepatitis C virus: friend or foe?
Authors: Sugden Peter B , Cameron Barbara , Bull Rowena , White Peter A , Lloyd Andrew R
Published: May 2012

Hepatitis C virus (HCV) infection is a global pandemic associated with a growing disease burden due to cirrhosis and the consequent morbidity and mortality. Transmission is largely via blood‐to‐blood contact. Following primary infection, a minority of individuals clear the infection predominantly via cellular immune mechanisms, whereas the majority become chronically infected. Recent data suggest that a third outcome may also be possible, termed ‘occult' infection in which subjects who are known, or suspected to have previously been infected with HCV, no longer have viral RNA in their serum at levels detectable by sensitive commercial assays, but do have virus detected by ultra‐sensitive techniques. Occult infection has also been detected in peripheral blood mononuclear cells, which may indicate an extra‐hepatic reservoir of the virus. Although the clinical significance of occult infection remains unknown, most authors have raised concerns of recrudescent infection. Here we critically review the published literature, suggest further avenues of investigation and propose that occult infection may be beneficial to the host by maintaining immunological memory to protect against reinfection.
The Microbiota of the Gut in Preschool Children With Normal and Excessive Body Weight
Authors: Karlsson Caroline L.J. , Önnerfält Jenny , Xu Jie , Molin Göran , Ahrné Siv , Thorngren‐Jerneck Kristina
Published: May 2012

The aim of this study was to investigate the gut microbiota in preschool children with and without overweight and obesity. Twenty overweight or obese children and twenty children with BMI within the normal range (age: 4–5 years) were recruited from the south of Sweden. The gut microbiota was accessed by quantitative PCR (qPCR) and terminal restriction fragment length polymorphism and calprotectin was measured in feces. Liver enzymes were quantified in obese/overweight children. The concentration of the gram‐negative family Enterobacteriaceae was significantly higher in the obese/overweight children (P = 0.036), whereas levels of Desulfovibrio and Akkermansia muciniphila‐like bacteria were significantly lower in the obese/overweight children (P = 0.027 and P = 0.030, respectively). No significant differences were found in content of Lactobacillus, Bifidobacterium or the Bacteroides fragilis group. The diversity of the dominating bacterial community tended to be less diverse in the obese/overweight group, but the difference was not statistically significant. Concentration of Bifidobacterium was inversely correlated to alanine aminotransferase (ALT) in obese/overweight children. The fecal levels of calprotectin did not differ between the study groups. These findings indicate that the gut microbiota differed among preschool children with obesity/overweight compared with children with BMI within the normal range.
The Relation of Adiposity to Cognitive Control and Scholastic Achievement in Preadolescent Children
Authors: Kamijo Keita , Khan Naiman A. , Pontifex Matthew B. , Scudder Mark R. , Drollette Eric S. , Raine Lauren B. , Evans Ellen M. , Castelli Darla M. , Hillman Charles H.
Published: May 2012

Adiposity may be negatively associated with cognitive function in children. However, the findings remain controversial, in part due to the multifaceted nature of cognition and perhaps the lack of accurate assessment of adiposity. The aim of this study was to clarify the relation of weight status to cognition in preadolescent children using a comprehensive assessment of cognitive control, academic achievement, and measures of adiposity. Preadolescent children between 7 and 9 years (n = 126) completed Go and NoGo tasks, as well as the Wide Range Achievement Test 3rd edition (WRAT3), which measures achievement in reading, spelling, and arithmetic. In addition to BMI, fat mass was measured using dual‐energy X‐ray absorptiometry (DXA). Data were analyzed with multiple regression analysis, controlling for confounding variables. Analyses revealed that BMI and fat mass measured via DXA were negatively associated with cognitive control, as children with higher BMI and fat mass exhibited poorer performance on the NoGo task requiring extensive amounts of inhibitory control. By contrast, no relation of weight status to performance was observed for the Go task requiring smaller amounts of cognitive control. Higher BMI and fat mass were also associated with lower academic achievement scores assessed on the WRAT3. These data suggest that adiposity is negatively and selectively associated with cognitive control in preadolescent children. Given that cognitive control has been implicated in academic achievement, the present study provides an empirical basis for the negative relationship between adiposity and scholastic performance.
Lack of CC chemokine ligand 2 differentially affects inflammation and fibrosis according to the genetic background in a murine model of steatohepatitis
Authors: Galastri Sara , Zamara Elena , Milani Stefano , Novo Erica , Provenzano Angela , Delogu Wanda , Vizzutti Francesco , Sutti Salvatore , Locatelli Irene , Navari Nadia , Vivoli Elisa , Caligiuri Alessandra , Pinzani Massimo , Albano Emanuele , Parola Maurizio , Marra Fabio
Published: May 2012

Expression of CCL2 (CC chemokine ligand 2) (or monocyte chemoattractant protein-1) regulates inflammatory cell infiltration in the liver and adipose tissue, favouring steatosis. However, its role in the pathogenesis of steatohepatitis is still uncertain. In the present study, we investigated the development of non-alcoholic steatohepatitis induced by an MCD diet (methionine/choline-deficient diet) in mice lacking the CCL2 gene on two different genetic backgrounds, namely Balb/C and C57/Bl6J. WT (wild-type) and CCL2-KO (knockout) mice were fed on a lipid-enriched MCD diet or a control diet for 8 weeks. In Balb/C mice fed on the MCD diet, a lack of CCL2 was associated with lower ALT (alanine transaminase) levels and reduced infiltration of inflammatory cells, together with a lower generation of oxidative-stress-related products. Sirius Red staining demonstrated pericellular fibrosis in zone 3, and image analysis showed a significantly lower matrix accumulation in CCL2-KO mice. This was associated with reduced hepatic expression of TGF-β (transforming growth factor-β), type I procollagen, TIMP-1 (tissue inhibitor of metalloproteinases-1) and α-smooth muscle actin. In contrast, in mice on a C57Bl/6 background, neither ALT levels nor inflammation or fibrosis were significantly different comparing WT and CCL2-KO animals fed on an MCD diet. In agreement, genes related to fibrogenesis were expressed to comparable levels in the two groups of animals. Comparison of the expression of several genes involved in inflammation and repair demonstrated that IL (interleukin)-4 and the M2 marker MGL-1 (macrophage galactose-type C-type lectin 1) were differentially expressed in Balb/C and C57Bl/6 mice. No significant differences in the degree of steatosis were observed in all groups of mice fed on the MCD diet. We conclude that, in experimental murine steatohepatitis, the effects of CCL2 deficiency are markedly dependent on the genetic background.
The Future of the Information Systems Discipline: A Response to Walsham
Authors: March Salvatore T. , Niederman Fred
Published: May 2012

We must look ahead at today's radical changes in technology, not just as forecasters but as actors charged with designing and bringing about a sustainable and acceptable world. New knowledge gives us power for change: for good or ill, for knowledge is neutral. The problems we face go well beyond technology: problems of living in harmony with nature, and most important, living in harmony with each other. Information technology, so closely tied to the properties of the human mind, can give us, if we ask the right questions, the special insights we need to advance these goals.

Herbert A. Simon (2000)
Theoretical investigation of rare gas hydride cations: HRgN2+ (Rg=He, Ar, Kr, and Xe)
Authors: Jayasekharan T. , Ghanty T. K.
Published: May 2012

Rare gas containing protonated nitrogen cations, HRgN2+ (Rg=He, Ar, Kr, and Xe), have been predicted using quantum computational methods. HRgN2+ ions exhibit linear structure (C∞v symmetry) at the minima and show planar structure (Cs symmetry) at the transition state. The stability is determined by computing the energy differences between the predicted ions and its various unimolecular dissociation products. Analysis of energy diagram indicates that HXeN2+ is thermodynamically stable with respect to dissociated products while HHeN2+, HArN2+, and HKrN2+ ions are metastable with small barrier heights. Moreover, the computed intrinsic reaction coordinate analysis also confirms that the minima and the 2-body global dissociation products are connected through transition states for the metastable ions. The coupled-cluster theory computed dissociation energies corresponding to the 2-body dissociation (HN2+ + Rg) is −288.4, −98.3, −21.5, and 41.4 kJ mol−1 for HHeN2+, HArN2+, HKrN2+, and HXeN2+ ions, respectively. The dissociation energies are positive for all the other channels implying that the predicted ions are stable with respect to other 2- and 3-body dissociation channels. Atoms-in-molecules analysis indicates that predicted ions may be best described as HRg+N2. It should be noted that the energetic of HXeN2+ ion is comparable to that of the experimentally observed stable mixed cations, viz. (RgHRg′)+. Therefore, it may be possible to prepare and characterize HXeN2+ ions in an electron bombardment matrix isolation technique.
Exciton dissociation and charge trapping at poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester bulk heterojunction interfaces: Photo-induced threshold voltage shifts in organic field-effect transistors and solar cells
Authors: Park Byoungnam , You Nam-Ho , Reichmanis Elsa
Published: May 2012

Photoinduced charge transfer at an electron donor/acceptor interface is one of the most crucial processes in determining the power conversion efficiency of organic solar cell devices. Here, we address exciton dissociation and charge carrier trapping at poly(3-hexylthiophene) (P3HT)/phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction interfaces electrically using a field effect transistor (FET). With a P3HT/PCBM composite film, we elucidated exciton dissociation and charge carrier recombination assisted by localized electronic states at the P3HT/PCBM interface via photoinduced threshold voltage shift measurements with respect to wavelength using FETs in combination with organic solar cell devices. Interestingly, the combination of light coupled with a significant quantity of PCBM within the film was required to observe ambipolar charge transport in P3HT/PCBM FETs. This phenomenon was addressed by filling of electron traps associated with PCBM under illumination and formation of the conducting pathways for both electrons and holes. A high density of carrier traps at the interface suggested by the FET results was confirmed in light intensity dependent short-circuit current (Jsc) and open-circuit voltage (Voc) measurements using solar cell devices.
GaP heteroepitaxy on Si(001): Correlation of Si-surface structure, GaP growth conditions, and Si-III/V interface structure
Authors: Beyer A. , Ohlmann J. , Liebich S. , Heim H. , Witte G. , Stolz W. , Volz K.
Published: May 2012

GaP-layers on Si(001) can serve as pseudo-substrates for a variety of novel optoelectronic devices. The quality of the GaP nucleation layer is a crucial parameter for the performance of such devices. Especially, anti-phase domains (APDs) evolving at mono-atomic steps on the Si-surface can affect the quality of a layer adversely. The size, shape, and possible charge of the APDs and their boundaries depend on the polarity of the surrounding crystal. The observed polarity of the GaP is caused by the A-type double step configuration of the Si-surface reconstruction prior to GaP growth and the prevalent binding of Ga to Si under optimized growth conditions. The polarity of the GaP-layer and hence the atomic configuration at the Si-III/V interface can be changed by altering the growth conditions. With this knowledge, defect-free GaP/Si(001) templates for III/V device integration on Si-substrates can be grown.
Two-color GaN/AlGaN quantum cascade detector at short infrared wavelengths of 1 and 1.7 μm
Authors: Sakr S. , Giraud E. , Dussaigne A. , Tchernycheva M. , Grandjean N. , Julien F. H.
Published: May 2012

A two-color GaN-based quantum cascade detector is demonstrated. This photodetector operates simultaneously at a peak wavelength of 1.7 and 1 μm at room temperature without any external voltage. These peaks correspond, respectively, to the e1e2 and e1e3 intersubband absorption of the active GaN quantum well. The extractor has been designed to allow for efficient transfer of electrons from both the e2 and e3 states to the next period. The 1 μm detected wavelength is the shortest value reported for an intersubband semiconductor based detector.
Structural characterization of Ti-15Mo alloy used as biomaterial by Rietveld method
Authors: Severino Martins José Roberto , Grandini Carlos Roberto
Published: May 2012

The biochemical and mechanical behavior of titanium alloys has been studied extensively for a variety of applications in the aerospace and biomedical fields. In the literature, there are studies that relate the microstructure and the phases of the material with its properties; however, there is little information that quantifies each phase and relates this to its properties. In addition, little has been done to analyze the effects of oxygen and heat treatment on the alloy’s structure. In this paper, the effect of doping with oxygen and the effect of heat treatments on structural properties of Ti-15Mo alloy used as biomaterials is examined using scanning electron microscopy, x-ray diffraction, and diffractogram analysis using the Rietveld method.