bluuebunny/crossref_metadata_2025 huggingface dataset:
Cognitive behaviour therapy training in a developing country: a pilot study in Tanzania
Authors: Stone Lydia , Warren Fiona
Published: December 2011

Cognitive behaviour therapy (CBT) has been found to be effective in treating mental health problems in the UK, but little has been done to evaluate the potential of CBT in developing countries. This paper aims to discuss the development and implementation of a CBT training course for clinicians working in Tanzania's main psychiatric hospital in the capital city, Dodoma. A 12-session training course in CBT was delivered to nine clinicians. An outcome evaluation was conducted using multiple measures and methods, taken before and after the training. Information on cultural adaptations of the training was obtained. All participants completed the course, but there were several obstacles to full completion of the evaluation measures. Despite this, there were significant improvements in clinicians’ basic understanding of CBT concepts, and their ability to apply the CBT model to formulate and recommend treatment strategies in response to a clinical case. Qualitative information indicated the potential of developing CBT training and implementation further. As a pilot study, this investigation shows the promise that CBT holds for mental health services in Tanzania. Further research into the training and clinical effectiveness of CBT in Tanzania is indicated.
Interpretation of hydrologic trends from a water balance perspective: The role of groundwater storage in the Budyko hypothesis
Authors: Istanbulluoglu Erkan , Wang Tiejun , Wright Olivia M. , Lenters John D.
Published: December 2011

We investigate the observed positive trends in annual runoff in several basins in central Nebraska using the Budyko hypothesis as a diagnostic tool. In basins where runoff is dominated by base flow we found that the estimated annual evapotranspiration (ETa) to precipitation (P) ratio (ETa/P) from data is negatively related to the aridity index (ETp/P, where ETp is potential annual evapotranspiration). This observation is inconsistent with the Budyko hypothesis. We hypothesized that the observed negative trend results from significant interannual changes in basin water storage. This hypothesis is tested using data from groundwater monitoring wells in the Sand Hills region of Nebraska. Plots of the yearly changes in groundwater storage versus the annual aridity index revealed the mean annual aridity index as a critical climatological variable that controls basin storage gain‐loss dynamics. For the same absolute deviation from the mean climate, we found that a wetter year leads to a larger gain in groundwater storage than the net loss in a drier year. We argue that this storage gain‐loss behavior builds a climate memory in the hydrologic system, causing persistence and statistically significant trends in annual runoff. A parsimonious model was developed that couples the Budyko hypothesis with a linear reservoir equation for base flow and was used to examine the possible causes of observed positive trends of annual runoff. We found that subtle, statistically insignificant, increases in annual P have led to positive and statistically insignificant trends in annual ETa and P − ETa. Annual runoff, on the other hand, was predicted to have high persistence and statistical significance, consistent with observations. Further model sensitivity analyses showed that increasing the size of the groundwater reservoir is associated with increased long‐term (multidecadal) persistence in annual runoff and translates high‐frequency, high‐amplitude variation in climate to low‐frequency, low‐amplitude runoff response. Our results underscore the importance of evaluating apparent trends in any system variable in a complete water budget context.
Measurement and modeling of ablation of the bottom of supraglacial lakes in western Greenland
Authors: Tedesco M. , Lüthje M. , Steffen K. , Steiner N. , Fettweis X. , Willis I. , Bayou N. , Banwell A.
Published: December 2011

We report measurements of ablation rates of the bottom of two supraglacial lakes and of temperatures at different depths collected during the summers of 2010 and 2011 in west Greenland. To our knowledge, this is the first time that such data sets are reported and discussed in the literature. The measured ablation rates at the bottom of the two lakes are of the order of ∼6 cm/day, versus a rate of ∼2.5–3 cm/day in the case of bare ice of surrounding areas. Though our measurements suggest the presence of a vertical temperature gradient, it is not possible to draw final conclusions as the measured gradient is smaller than the accuracy of our temperature sensors. In‐situ measurements are compared with the results of a thermodynamic model forced with the outputs of a regional climate model. In general, the model is able to satisfactorily reproduce the measured quantities with RMSE of the order of 3–4 cm for the ablation and ∼1.5°C in the case of water temperature. Our results confirm that the ablation at the bottom of supraglacial lakes plays an important role on the overall lake volume with the ablation in the case of ice covered by a lake being 110–135% of that over bare ice at nearby locations. Beside ice sheet hydrological implications, melting at the bottom of a supraglacial lake might affect estimates of lake volume from spaceborne visible and near‐infrared measurements.
Observational evidence of ionospheric migrating tide modification during the 2009 stratospheric sudden warming
Authors: Lin J. T. , Lin C. H. , Chang L. C. , Huang H. H. , Liu J. Y. , Chen A. B. , Chen C. H. , Liu C. H.
Published: December 2011

In this paper, modifications of the ionospheric tidal signatures during the 2009 stratospheric sudden warming (SSW) event are studied by applying atmospheric tidal analysis to ionospheric electron densities observed using radio occultation soundings of FORMOSAT‐3/COSMIC. The tidal analysis indicates that the zonal mean and major migrating tidal components (DW1, SW2 and TW3) decrease around the time of the SSW, with 1.5–4 hour time shifts in the daily time of maximum around EIA and middle latitudes. The typical ionospheric SSW signature: a semi‐diurnal variation of the ionospheric electron density, featuring an earlier commencement and subsidence of EIA, can be reproduced by differencing the migrating tides before and during the SSW period. Our results also indicate that the migrating tides represent ∼80% of the ionospheric tidal components at specific longitudes, suggesting that modifications of the migrating tides may be the major driver for producing ionospheric changes observed during SSW events, accounting for greater variability than the nonmigrating tides that have been the focus of previous studies.
Multipayload interferometric wave vector determination of auroral hiss
Authors: Lundberg E. T. , Kintner P. M. , Powell S. P. , Lynch K. A.
Published: December 2011

We extend traditional, single payload, interferometric techniques to a multiple payload sounding rocket mission, and apply these techniques to measure the parallel and perpendicular wavelength of auroral VLF hiss from 8 kHz–20 kHz. We model the wavelength distribution of auroral hiss as a cone at a fixed angle with respect to the magnetic field that is isotropically distributed in the perpendicular plane. We apply this model to calculate the interferometric observables, coherency and phase, for a sounding rocket mission whose wave electric field receivers are on payloads that are separated 2–3 km along the magnetic field and 55–200 m across the magnetic field. Using an interferometer formed by comparing the collinear sphere‐to‐skin electric field antennas on a single payload, we estimate a lower limit on the perpendicular wavelength of VLF hiss of ∼60 m. Analysis of coherency and phase due to this conical wave vector distribution for a multipayload interferometer reveals the existence of a spin dependent coherency pattern. From this coherency pattern we generate an upper limit perpendicular wavelength estimate for VLF hiss of ∼350 m. The inter‐payload phase gives an accurate estimate of the parallel wavelength of ∼6000–8000 m. This parallel wavelength is combined with the lower (upper) limit perpendicular wavelength estimates to generate upper (lower) limits on wave‐normal angle. These limits are each within one degree of the predicted electrostatic whistler wave resonance cone angle verifying that VLF hiss propagates on this resonance cone.
Properties of Sarychev sulphate aerosols over the Arctic
Authors: O'Neill N. T. , Perro C. , Saha A. , Lesins G. , Duck T. J. , Eloranta E. W. , Nott G. J. , Hoffman A. , Karumudi M. L. , Ritter C. , Bourassa A. , Abboud I. , Carn S. A. , Savastiouk V.
Published: December 2011

Aerosols from the Sarychev Peak volcano entered the Arctic region less than a week after the strongest SO2eruption on June 15 and 16, 2009 and had, by the first week in July, spread out over the entire Arctic region. These predominantly stratospheric aerosols were determined to be sub‐micron in size and inferred to be composed of sulphates produced from the condensation of SO2gases emitted during the eruption. Average (500 nm) Sarychev‐induced stratospheric optical depths (SOD) over the Polar Environmental Atmospheric Research Laboratory (PEARL) at Eureka (Nunavut, Canada) were found to be between 0.03 and 0.05 during the months of July and August, 2009. This estimate, derived from sunphotometry and integrated lidar backscatter profiles was consistent with averages derived from lidar estimates over Ny‐Ålesund (Spitsbergen). The Sarychev SOD e‐folding time at Eureka, deduced from lidar profiles, was found to be approximately 4 months relative to a regression start date of July 27. These profiles initially revealed the presence of multiple Sarychev plumes between the tropopause and about 17 km altitude. After about two months, the complex vertical plume structures had collapsed into fewer, more homogeneous plumes located near the tropopause. It was found that the noisy character of daytime backscatter returns induced an artifactual minimum in the temporal, pan‐Arctic, CALIOP SOD response to Sarychev sulphates. A depolarization ratio discrimination criterion was used to separate the CALIOP stratospheric layer class into a low depolarization subclass which was more representative of Sarychev sulphates. Post‐SAT (post Sarychev Arrival Time) retrievals of the fine mode effective radius (reff,f) and the logarithmic standard deviation for two Eureka sites and Thule (Greenland) were all close to 0.25 μm and 1.6 respectively. The stratospheric analogue to the columnar reff,f average was estimated to be reff,f(+) = 0.29 μm for Eureka data. Stratospheric, Raman lidar retrievals at Ny‐Ålesund, yielded a post‐SAT average of reff,f(+) = 0.27 μm. These results are ∼50% larger than the background stratospheric‐aerosol value. They are also about a factor of two larger than modeling values used in recent publications or about a factor of five larger in terms of (per particle) backscatter cross section.
Water vapor sources for Yangtze River Valley rainfall: Climatology, variability, and implications for rainfall forecasting
Authors: Wei Jiangfeng , Dirmeyer Paul A. , Bosilovich Michael G. , Wu Renguang
Published: December 2011

The method of calculating water vapor flux can show the paths of moisture transport but cannot easily identify the sources and sinks of water vapor. In this study, we estimate the evaporative moisture sources for the Yangtze River Valley (YRV) rainfall with a water vapor back‐trajectory method, using meteorological data from the Modern Era Retrospective‐analysis for Research and Applications (MERRA). The major moisture sources and their relative contributions show large seasonal variations. The moisture from the Bay of Bengal and the western Pacific usually compensate each other both during the evolution of YRV wet season (April–September) and interannually for the wet months (peak in August). The major direct moisture sources are over YRV and its major moisture transport pathways over land, rather than over the ocean, but the ocean is important in initiating the moisture transfer. However, over these important land moisture sources, surface evapotranspiration is not controlled by soil wetness and has weak impact on the variability of rainfall. Local moisture recycling over YRV is mostly a passive response to rainfall and circulation changes. The prediction of YRV rainy season rainfall thus depends more on the knowledge of large‐scale circulations and monsoons than land surface conditions.
On the application of differential phase measurements to study the zonal large scale wave structure (LSWS) in the ionospheric electron content
Authors: Tulasi Ram S. , Yamamoto M. , Tsunoda R. T. , Thampi S. V. , Gurubaran S.
Published: December 2011

The GNU Radio Beacon Receiver (GRBR) Network has been recently established to provide coverage of Southeast Asia and Pacific low‐latitude regions, with planned extensions into the Indian and African longitude sectors. With the availability of CERTO (Coherent Electromagnetic Radio Tomography) beacon transmissions from Communication/Navigation Outage Forecasting System (C/NOFS) satellite, which is in a unique low‐inclination (13°) orbit, it is now possible to study zonal large scale wave structure (LSWS) in ionospheric total electron content (TEC) with fine spatial resolution over a wide longitudinal region. An automated procedure to determine absolute TEC from relative TEC measurements for low inclination CNOFS orbits has been implemented through a simple single station procedure for initial offset estimation, which is shown to be consistent with the better established two station method and with observations from a Digisonde. The LSWS is extracted by subtracting the background variation from longitudinal variation of TEC. The upwellings of LSWS manifest as depletions in the residual TEC variations. Further, these zonal structures have been found, in general, to be aligned with geomagnetic field lines, and the scintillation patches have been found to align with the west walls of TEC depletions. This spatial alignment recapitulates the premise that the observed zonal wave‐like structures in TEC are the manifestations of bottom side LSWS. Hence, the methodology presented in this paper, would prove useful in future, to study the characteristics of LSWS on a regular basis.
Structure Prediction and Functional Characterization of ERG Proteins Involved in Ergosterol Biosynthetic Pathway of Candida albicans
Authors: Roy Sudeep , Luqman Suaib , Sharma Ashok
Published: December 2011

The ERG proteins and enzymes of the ergosterol biosynthetic pathway has been the subject of intensive investigation as a target for several classes of antifungal agents used to treat C. albicans infection. Over the past few decades, a number of drugs and inhibitors with wide spectrum of activity, low toxicity and defined targets have been introduced. Several lines of evidence suggest that allylamines targets squalene epoxidase (ERG1), morpholines affects sterol C8-C7 isomerase (ERG2) and sterol reductase (ERG24), azoles inhibits a cytochrome P450 (ERG11) responsible for the 14 α-demethylation of lanosterol and C-5 sterol desaturase (ERG3) and polyenes binds to ergosterol that leads to the damage of cell plasma membrane, ensuing in leakage of intracellular ions. However, little information about the experimental structure (X-ray and NMR) of proteins from ergosterol biosynthetic pathway is available in RCSB Protein Databank (PDB). Since ERG proteins play a key role in metabolic pathway of ergosterol, their 3D structures are essential to determine most of their functions. Homology modeling approach was employed for comparative modeling. Modeller 9v7 and I-Tasser programs were utilized to serve our purpose. The modeled proteins were further validated by Procheck, Verify-3D, ERRAT and PROVE servers. Expasy’s Prot-param server and Cys_rec tool was used for physico-chemical and functional characterization of these proteins. Studies of secondary structure of these proteins were carried out using computational program, Profunc. Swiss-pdb viewer was used to visualize and analyze homology derived structures. The modeled structures of 12 ERG proteins have been submitted and are available in Protein Model Database (PMDB) so that they become accessible to other users for further studies.
A taxonomic review of Homoranthus (Myrtaceae: Chamelaucieae)
Authors: Copeland Lachlan M. , Craven Lyn A. , Bruhl Jeremy J.
Published: December 2011

Homoranthus A.Cunn. ex Schauer, an Australian endemic genus of shrubs in the Myrtaceae, is reviewed. A total of 31 species is recognised for the genus, including the following eight new species which are here described for the first time: H. bebo L.M.Copel., H. brevistylis L.M.Copel., H. bruhlii L.M.Copel., H. clarksonii L.M.Copel., H. cummingii L.M.Copel, H. elusus L.M.Copel., H. inopinatus L.M.Copel., J.Holmes & G.Holmes and H. vagans L.M.Copel. H. bornhardtiensis J.T.Hunter is synonymised under H. prolixus Craven & S.R.Jones. A key to identify all species of Homoranthus is provided and notes are given on the phenology, distribution, habitat, conservation status and distinguishing features of each species. The distribution of all species of Homoranthus is mapped and illustrations are provided for each of the eight new species.
A taxonomic revision of the Stylidium despectum group (Stylidiaceae) from southern Australia
Authors: Wege Juliet A.
Published: December 2011

A morphological review of the diminutive annual species from the Stylidium despectum R.Br. group (Stylidiaceae) is presented. Twelve species are recognised, of which 10 are endemic in the south-west of Western Australia and two are widespread across southern temperate Australia. Following examination of type material, herbarium collections and field observations, a change of circumscription is presented for S. despectum and S. inundatum R.Br. The former name is applied to a widespread species that occurs in Western Australia, South Australia, Victoria, New South Wales and Tasmania, and is characterised by scattered or rosetted leaves, pink and/or white corolla lobes in a fan-shaped arrangement, and an immobile floral column. S. brachyphyllum Sond. is newly placed into synonymy under S. despectum and a lectotype selected. S. inundatum is redefined as a south-western Australian endemic with scattered leaves, vertically-paired or evenly spreading corolla lobes, and a mobile floral column. A lectotype is designated for S. inundatum, and S. sidjamesii Lowrie & Kenneally is treated as conspecific. S. beaugleholei J.H.Willis is confirmed for Western Australia, South Australia, Victoria and Tasmania. S. asymmetricum Wege, a new and apparently rare species from the Northern Jarrah Forest in south-western Australia, is formally described and revised descriptions are provided for S. longitubum Benth., S. pygmaeum R.Br., S. rhipidium F.L.Erickson & J.H.Willis, S. roseoalatum F.L.Erickson & J.H.Willis, S. roseonanum Carlquist, S. tinkeri Lowrie & Kenneally, S. utricularioides Benth. and S. xanthopis F.L.Erickson & J.H.Willis. A lectotype is designated for S. longitubum Benth. and S. utricularioides var. rosulatum Mildbr. is newly placed into synonymy under S. roseoalatum. A key to species is provided, along with photographs to aid identification. Further field-based studies are required to refine the taxonomy of this group and to better understand the distribution, rarity and conservation status of some of the taxa. In Western Australia, seven species are listed as being of conservation concern, of which S. asymmetricum, S. tinkeri and S. xanthopis require immediate further survey to ascertain whether they should be given Threatened Flora status.
Spatial and temporal patterns of wildfire ignitions in Canada from 1980 to 2006
Authors: Gralewicz Nicholas J. , Nelson Trisalyn A. , Wulder Michael A.
Published: December 2011

A spatially explicit baseline measure of historic, current and future wildfire ignition expectations is required to monitor and understand changes in fire occurrence, the distribution of which climate change is anticipated to modify. Using spatial–temporal patterns of fire in Canada, we present a method to identify baseline expectations and ignition trends between 1980 and 2006 across 1-km spatial units. Kernel density estimates of wildfire ignitions and temporal trajectory metrics were calculated to describe expected ignition density, variability from expected density, and increasing or decreasing density trends. Baseline ignition expectations and trends were used to create unique fire ignition regimes and assess anthropogenic influence on ignitions. Fire ignition densities decreased exponentially as distance to road or populated place increased, and largest ignition trends occurred closest to both variables. Fire ignition regime delineation was more dependent on human transportation networks than human settlement. These findings provide a unique approach to quantifying ignition expectations. This research highlights the potential of this baseline approach for monitoring efforts and fire–environment interaction research and offers a preliminary spatially explicit model of wildfire occurrence expectations in Canada.
Fuel loadings 5 years after a bark beetle outbreak in south-western USA ponderosa pine forests
Authors: Hoffman Chad M. , Hull Sieg Carolyn , McMillin Joel D. , Fulé Peter Z.
Published: December 2011

Landscape-level bark beetle (Coleoptera: Curculionidae, Scolytinae) outbreaks occurred in Arizona ponderosa pine (Pinus ponderosa Dougl. ex Law.) forests from 2001 to 2003 in response to severe drought and suitable forest conditions. We quantified surface fuel loadings and depths, and calculated canopy fuels based on forest structure attributes in 60 plots established 5 years previously on five national forests. Half of the plots we sampled in 2007 had bark beetle-caused pine mortality and half did not have mortality. Adjusting for differences in pre-outbreak stand density, plots with mortality had higher surface fuel and lower canopy fuel loadings 5 years after the outbreak compared with plots without mortality. Total surface fuels averaged 2.5 times higher and calculated canopy fuels 2 times lower in plots with mortality. Nearly half of the trees killed in the bark beetle outbreak had fallen within 5 years, resulting in loadings of 1000-h woody fuels above recommended ranges for dry coniferous forests in 20% of the mortality plots. We expect 1000-h fuel loadings in other mortality plots to exceed recommended ranges as remaining snags fall to the ground. This study adds to previous work that documents the highly variable and complex effects of bark beetle outbreaks on fuel complexes.
Reconstruction of
Arabidopsis
metabolic network models accounting for subcellular compartmentalization and tissue-specificity
Authors: Mintz-Oron Shira , Meir Sagit , Malitsky Sergey , Ruppin Eytan , Aharoni Asaph , Shlomi Tomer
Published: December 2011

Plant metabolic engineering is commonly used in the production of functional foods and quality trait improvement. However, to date, computational model-based approaches have only been scarcely used in this important endeavor, in marked contrast to their prominent success in microbial metabolic engineering. In this study we present a computational pipeline for the reconstruction of fully compartmentalized tissue-specific models of
Arabidopsis thaliana
on a genome scale. This reconstruction involves automatic extraction of known biochemical reactions in
Arabidopsis
for both primary and secondary metabolism, automatic gap-filling, and the implementation of methods for determining subcellular localization and tissue assignment of enzymes. The reconstructed tissue models are amenable for constraint-based modeling analysis, and significantly extend upon previous model reconstructions. A set of computational validations (i.e., cross-validation tests, simulations of known metabolic functionalities) and experimental validations (comparison with experimental metabolomics datasets under various compartments and tissues) strongly testify to the predictive ability of the models. The utility of the derived models was demonstrated in the prediction of measured fluxes in metabolically engineered seed strains and the design of genetic manipulations that are expected to increase vitamin E content, a significant nutrient for human health. Overall, the reconstructed tissue models are expected to lay down the foundations for computational-based rational design of plant metabolic engineering. The reconstructed compartmentalized
Arabidopsis
tissue models are MIRIAM-compliant and are available upon request.
Activity-dependent modulation of endocytosis by calmodulin at a large central synapse
Authors: Yao Lijun , Sakaba Takeshi
Published: December 2011

Although Ca
2+
/calmodulin has been suggested to play a role during endocytosis, it remains unknown if binding of Ca
2+
to calmodulin is essential for initiating endocytosis or if this interaction only has a modulatory effect on endocytosis. In this study, using time-resolved capacitance measurements at the rat calyx of Held synapse, the role of calmodulin in endocytosis was examined. Our results demonstrate that blocking calmodulin with an inhibitory peptide, which interfers with the binding of calmodulin to downstream targets, slowed the rate of endocytosis, but only when accompanied by high Ca
2+
influx. In response to a short train of action potential-like stimulation, blocking calmodulin had no effect on endocytosis. Furthermore, we have identified conditions in which inhibition of calmodulin fails to affect the rate of endocytosis, but nevertheless retards recruitment of synaptic vesicles to the fast-releasing vesicle pool responsible for synchronous release. The results indicate that calmodulin facilitates endocytosis in an activity-dependent manner but is not mandatory for endocytosis, and suggest that calmodulin modulates an endocytotic intermediate process, which in turn affects synaptic vesicle recruitment and membrane fission.
Nature of curvature coupling of amphiphysin with membranes depends on its bound density
Authors: Sorre Benoît , Callan-Jones Andrew , Manzi John , Goud Bruno , Prost Jacques , Bassereau Patricia , Roux Aurélien
Published: December 2011

Cells are populated by a vast array of membrane-binding proteins that execute critical functions. Functions, like signaling and intracellular transport, require the abilities to bind to highly curved membranes and to trigger membrane deformation. Among these proteins is amphiphysin 1, implicated in clathrin-mediated endocytosis. It contains a Bin-Amphiphysin-Rvs membrane-binding domain with an N-terminal amphipathic helix that senses and generates membrane curvature. However, an understanding of the parameters distinguishing these two functions is missing. By pulling a highly curved nanotube of controlled radius from a giant vesicle in a solution containing amphiphysin, we observed that the action of the protein depends directly on its density on the membrane. At low densities of protein on the nearly flat vesicle, the distribution of proteins and the mechanical effects induced are described by a model based on spontaneous curvature induction. The tube radius and force are modified by protein binding but still depend on membrane tension. In the dilute limit, when practically no proteins were present on the vesicle, no mechanical effects were detected, but strong protein enrichment proportional to curvature was seen on the tube. At high densities, the radius is independent of tension and vesicle protein density, resulting from the formation of a scaffold around the tube. As a consequence, the scaling of the force with tension is modified. For the entire density range, protein was enriched on the tube as compared to the vesicle. Our approach shows that the strength of curvature sensing and mechanical effects on the tube depends on the protein density.
The nuclear receptor REV-ERBα mediates circadian regulation of innate immunity through selective regulation of inflammatory cytokines
Authors: Gibbs Julie E. , Blaikley John , Beesley Stephen , Matthews Laura , Simpson Karen D. , Boyce Susan H. , Farrow Stuart N. , Else Kathryn J. , Singh Dave , Ray David W. , Loudon Andrew S. I.
Published: December 2011

Diurnal variation in inflammatory and immune function is evident in the physiology and pathology of humans and animals, but molecular mechanisms and mediating cell types that provide this gating remain unknown. By screening cytokine responses in mice to endotoxin challenge at different times of day, we reveal that the magnitude of response exhibited pronounced temporal dependence, yet only within a subset of proinflammatory cytokines. Disruption of the circadian clockwork in macrophages (primary effector cells of the innate immune system) by conditional targeting of a key clock gene (
bmal1
) removed all temporal gating of endotoxin-induced cytokine response in cultured cells and in vivo. Loss of circadian gating was coincident with suppressed
rev-erb
α expression, implicating this nuclear receptor as a potential link between the clock and inflammatory pathways. This finding was confirmed in vivo and in vitro through genetic and pharmacological modulation of
REV-ERB
α activity. Circadian gating of endotoxin response was lost in
rev-erb
α
−/−
mice and in cultured macrophages from these animals, despite maintenance of circadian rhythmicity within these cells. Using human macrophages, which show circadian clock gene oscillations and rhythmic endotoxin responses, we demonstrate that administration of a synthetic REV-ERB ligand, or genetic knockdown of
rev-erb
α expression, is effective at modulating the production and release of the proinflammatory cytokine IL-6. This work demonstrates that the macrophage clockwork provides temporal gating of systemic responses to endotoxin, and identifies REV-ERBα as the key link between the clock and immune function. REV-ERBα may therefore represent a unique therapeutic target in human inflammatory disease.
Collaborative learning in networks
Authors: Mason Winter , Watts Duncan J.
Published: December 2011

Complex problems in science, business, and engineering typically require some tradeoff between exploitation of known solutions and exploration for novel ones, where, in many cases, information about known solutions can also disseminate among individual problem solvers through formal or informal networks. Prior research on complex problem solving by collectives has found the counterintuitive result that inefficient networks, meaning networks that disseminate information relatively slowly, can perform better than efficient networks for problems that require extended exploration. In this paper, we report on a series of 256 Web-based experiments in which groups of 16 individuals collectively solved a complex problem and shared information through different communication networks. As expected, we found that collective exploration improved average success over independent exploration because good solutions could diffuse through the network. In contrast to prior work, however, we found that efficient networks outperformed inefficient networks, even in a problem space with qualitative properties thought to favor inefficient networks. We explain this result in terms of individual-level explore-exploit decisions, which we find were influenced by the network structure as well as by strategic considerations and the relative payoff between maxima. We conclude by discussing implications for real-world problem solving and possible extensions.
Variation in cognitive functioning as a refined approach to comparing aging across countries
Authors: Skirbekk Vegard , Loichinger Elke , Weber Daniela
Published: December 2011

Comparing the burden of aging across countries hinges on the availability of valid and comparable indicators. The Old Age Dependency Ratio allows only a limited assessment of the challenges of aging, because it does not include information on any individual characteristics except age itself. Existing alternative indicators based on health or economic activity suffer from measurement and comparability problems. We propose an indicator based on age variation in cognitive functioning. We use newly released data from standardized tests of seniors' cognitive abilities for countries from different world regions. In the wake of long-term advances in countries’ industrial composition, and technological advances, the ability to handle new job procedures is now of high and growing importance, which increases the importance of cognition for work performance over time. In several countries with older populations, we find better cognitive performance on the part of populations aged 50+ than in countries with chronologically younger populations. This variation in cognitive functioning levels may be explained by the fact that seniors in some regions of the world experienced better conditions during childhood and adult life, including nutrition, duration and quality of schooling, lower exposure to disease, and physical and social activity patterns. Because of the slow process of cohort replacement, those countries whose seniors already have higher cognitive levels today are likely to continue to be at an advantage for several decades to come.
Discovery of competing anaerobic and aerobic pathways in umpolung amide synthesis allows for site-selective amide
18
O-labeling
Authors: Shackleford Jessica P. , Shen Bo , Johnston Jeffrey N.
Published: December 2011

The mechanism of umpolung amide synthesis was probed by interrogating potential sources for the oxygen of the product amide carbonyl that emanates from the α-bromo nitroalkane substrate. Using a series of
18
O-labeled substrates and reagents, evidence is gathered to advance two pathways from the putative tetrahedral intermediate. Under anaerobic conditions, a nitro-nitrite isomerization delivers the amide oxygen from nitro oxygen. The same homolytic nitro-carbon fragmentation can be diverted by capture of the carbon radical intermediate with oxygen gas (O
2
) to deliver the amide oxygen from O
2
. This understanding was used to develop a straightforward protocol for the preparation of
18
O-labeled amides in peptides by simply performing the umpolung amide synthesis reaction under an atmosphere of

.
Mutations in the GW-repeat protein SUO reveal a developmental function for microRNA-mediated translational repression in
Arabidopsis
Authors: Yang Li , Wu Gang , Poethig R. Scott
Published: December 2011

Plant microRNAs (miRNAs) typically mediate RNA cleavage, but examples of miRNA-mediated translational repression have also been reported. However, the functional significance of this latter process is unknown. We identified
SUO
in a screen for
Arabidopsis
mutations that increase the accumulation of the miR156-regulated gene
SPL3
.
suo
has a loss-of-function phenotype characteristic of plants with reduced Argonaute (AGO)1 activity. An analysis of RNA and protein levels in
suo
mutants demonstrated that this phenotype is a consequence of a defect in miRNA-mediated translational repression; the effect of
suo
on vegetative phase change is attributable to a reduction in miR156/miR157 activity.
SUO
encodes a large protein with N-terminal bromo-adjacent homology (BAH) and transcription elongation factor S-II (TFS2N) domains and two C-terminal GW (glycine and tryptophan) repeats. SUO is present in the nucleus, and colocalizes with the processing-body component DCP1 in the cytoplasm. Our results reveal that SOU is a component of the miRNA pathway in
Arabidopsis
and demonstrate that translational repression is a functionally important aspect of miRNA activity in plants.
Evidence for formation of DNA repair centers and dose-response nonlinearity in human cells
Authors: Neumaier Teresa , Swenson Joel , Pham Christopher , Polyzos Aris , Lo Alvin T. , Yang PoAn , Dyball Jane , Asaithamby Aroumougame , Chen David J. , Bissell Mina J. , Thalhammer Stefan , Costes Sylvain V.
Published: December 2011

The concept of DNA “repair centers” and the meaning of radiation-induced foci (RIF) in human cells have remained controversial. RIFs are characterized by the local recruitment of DNA damage sensing proteins such as p53 binding protein (53BP1). Here, we provide strong evidence for the existence of repair centers. We used live imaging and mathematical fitting of RIF kinetics to show that RIF induction rate increases with increasing radiation dose, whereas the rate at which RIFs disappear decreases. We show that multiple DNA double-strand breaks (DSBs) 1 to 2 μm apart can rapidly cluster into repair centers. Correcting mathematically for the dose dependence of induction/resolution rates, we observe an absolute RIF yield that is surprisingly much smaller at higher doses: 15 RIF/Gy after 2 Gy exposure compared to approximately 64 RIF/Gy after 0.1 Gy. Cumulative RIF counts from time lapse of 53BP1-GFP in human breast cells confirmed these results. The standard model currently in use applies a linear scale, extrapolating cancer risk from high doses to low doses of ionizing radiation. However, our discovery of DSB clustering over such large distances casts considerable doubts on the general assumption that risk to ionizing radiation is proportional to dose, and instead provides a mechanism that could more accurately address risk dose dependency of ionizing radiation.
Evolution of human-driven fire regimes in Africa
Authors: Archibald Sally , Staver A. Carla , Levin Simon A.
Published: December 2011

Human ability to manipulate fire and the landscape has increased over evolutionary time, but the impact of this on fire regimes and consequences for biodiversity and biogeochemistry are hotly debated. Reconstructing historical changes in human-derived fire regimes empirically is challenging, but information is available on the timing of key human innovations and on current human impacts on fire; here we incorporate this knowledge into a spatially explicit fire propagation model. We explore how changes in population density, the ability to create fire, and the expansion of agropastoralism altered the extent and seasonal distribution of fire as modern humans arose and spread through Africa. Much emphasis has been placed on the positive effect of population density on ignition frequency, but our model suggests this is less important than changes in fire spread and connectivity that would have occurred as humans learned to light fires in the dry season and to transform the landscape through grazing and cultivation. Different landscapes show different limitations; we show that substantial human impacts on burned area would only have started ∼4,000 B.P. in open landscapes, whereas they could have altered fire regimes in closed/dissected landscapes by ∼40,000 B.P. Dry season fires have been the norm for the past 200–300 ky across all landscapes. The annual area burned in Africa probably peaked between 4 and 40 kya. These results agree with recent paleocarbon studies that suggest that the biomass burned today is less than in the recent past in subtropical countries.
Explosive eruption of coal and basalt and the end-Permian mass extinction
Authors: Ogden Darcy E. , Sleep Norman H.
Published: December 2011

The end-Permian extinction decimated up to 95% of carbonate shell-bearing marine species and 80% of land animals. Isotopic excursions, dissolution of shallow marine carbonates, and the demise of carbonate shell-bearing organisms suggest global warming and ocean acidification. The temporal association of the extinction with the Siberia flood basalts at approximately 250 Ma is well known, and recent evidence suggests these flood basalts may have mobilized carbon in thick deposits of organic-rich sediments. Large isotopic excursions recorded in this period are potentially explained by rapid venting of coal-derived methane, which has primarily been attributed to metamorphism of coal by basaltic intrusion. However, recently discovered contemporaneous deposits of fly ash in northern Canada suggest large-scale combustion of coal as an additional mechanism for rapid release of carbon. This massive coal combustion may have resulted from explosive interaction with basalt sills of the Siberian Traps. Here we present physical analysis of explosive eruption of coal and basalt, demonstrating that it is a viable mechanism for global extinction. We describe and constrain the physics of this process including necessary magnitudes of basaltic intrusion, mixing and mobilization of coal and basalt, ascent to the surface, explosive combustion, and the atmospheric rise necessary for global distribution.
Cultural diversification promotes rapid phenotypic evolution in Xavánte Indians
Authors: Hünemeier Tábita , Gómez-Valdés Jorge , Ballesteros-Romero Mónica , de Azevedo Soledad , Martínez-Abadías Neus , Esparza Mireia , Sjøvold Torstein , Bonatto Sandro L. , Salzano Francisco Mauro , Bortolini Maria Cátira , González-José Rolando
Published: December 2011

Shifts in social structure and cultural practices can potentially promote unusual combinations of allele frequencies that drive the evolution of genetic and phenotypic novelties during human evolution. These cultural practices act in combination with geographical and linguistic barriers and can promote faster evolutionary changes shaped by gene–culture interactions. However, specific cases indicative of this interaction are scarce. Here we show that quantitative genetic parameters obtained from cephalometric data taken on 1,203 individuals analyzed in combination with genetic, climatic, social, and life-history data belonging to six South Amerindian populations are compatible with a scenario of rapid genetic and phenotypic evolution, probably mediated by cultural shifts. We found that the Xavánte experienced a remarkable pace of evolution: the rate of morphological change is far greater than expected for its time of split from their sister group, the Kayapó, which occurred around 1,500 y ago. We also suggest that this rapid differentiation was possible because of strong social-organization differences. Our results demonstrate how human groups deriving from a recent common ancestor can experience variable paces of phenotypic divergence, probably as a response to different cultural or social determinants. We suggest that assembling composite databases involving cultural and biological data will be of key importance to unravel cases of evolution modulated by the cultural environment.
PLK1 phosphorylation of pericentrin initiates centrosome maturation at the onset of mitosis
Authors: Lee Kwanwoo , Rhee Kunsoo
Published: December 2011

The microtubule-organizing activity of the centrosome oscillates during the cell cycle, reaching its highest level at mitosis. At the onset of mitosis, the centrosome undergoes maturation, which is characterized by a drastic expansion of the pericentriolar matrix (PCM) and a robust increase in microtubule-organizing activity. It is known that PLK1 is critical for the initiation of centrosome maturation. In this paper, we report that pericentrin (PCNT), a PCM protein, was specifically phosphorylated by PLK1 during mitosis. Phosphoresistant point mutants of PCNT did not recruit centrosomal proteins, such as CEP192, GCP-WD (γ-complex protein with WD repeats), γ-tubulin, Aurora A, and PLK1, into the centrosome during mitosis. However, centrosomal recruitment of CEP215 depended on PCNT irrespective of its phosphorylation status. Furthermore, ectopic expression of PLK1-PCNT fusion proteins induced the centrosomal accumulation of CEP192, GCP-WD, and γ-tubulin even in interphase cells, mimicking centrosome maturation. Based on these results, we propose that PLK1-mediated phosphorylation of PCNT initiates centrosome maturation by organizing the spindle pole–specific PCM lattice.
Neuregulin/ErbB regulate neuromuscular junction development by phosphorylation of α-dystrobrevin
Authors: Schmidt Nadine , Akaaboune Mohammed , Gajendran Nadesan , Martinez-Pena y Valenzuela Isabel , Wakefield Sarah , Thurnheer Raphael , Brenner Hans Rudolf
Published: December 2011

Neuregulin (NRG)/ErbB signaling is involved in numerous developmental processes in the nervous system, including synapse formation and function in the central nervous system. Although intensively investigated, its role at the neuromuscular synapse has remained elusive. Here, we demonstrate that loss of neuromuscular NRG/ErbB signaling destabilized anchoring of acetylcholine receptors (AChRs) in the postsynaptic muscle membrane and that this effect was caused by dephosphorylation of α-dystrobrevin1, a component of the postsynaptic scaffold. Specifically, in mice in which NRG signaling to muscle was genetically or pharmacologically abolished, postsynaptic AChRs moved rapidly from the synaptic to the perisynaptic membrane, and the subsynaptic scaffold that anchors the AChRs was impaired. These defects combined compromised synaptic transmission. We further show that blockade of NRG/ErbB signaling abolished tyrosine phosphorylation of α-dystrobrevin1, which reduced the stability of receptors in agrin-induced AChR clusters in cultured myotubes. Our data indicate that NRG/ErbB signaling maintains high efficacy of synaptic transmission by stabilizing the postsynaptic apparatus via phosphorylation of α-dystrobrevin1.
Sub-200 ps spin transfer torque switching in in-plane magnetic tunnel junctions with interface perpendicular anisotropy
Authors: Zhao Hui , Glass Brian , Amiri Pedram Khalili , Lyle Andrew , Zhang Yisong , Chen Yu-Jin , Rowlands Graham , Upadhyaya Pramey , Zeng Zhongming , Katine J A , Langer Juergen , Galatsis Kosmas , Jiang Hongwen , Wang Kang L , Krivorotov Ilya N , Wang Jian-Ping
Published: December 2011

Ultrafast spin transfer torque (STT) switching in an in-plane MgO magnetic tunnel junction with 50 nm×150 nm elliptical shape was demonstrated in this paper. Switching speeds as short as 165 ps and 190 ps at 50% and 98% switching probabilities, respectively, were observed without external field assistance in a thermally stable junction with a 101% tunnelling magnetoresistance ratio. The minimum writing energy of P-AP switching for 50% and 98% switching probability are 0.16 pJ and 0.21 pJ, respectively. The observed ultrafast switching is believed to occur because of partially cancelled out-of-plane demagnetizing field in the free layer from interface perpendicular anisotropy between the MgO layer and the Co20Fe60B20 layer. High J/J
c0 ratio and magnetization nucleation at the edge of free layer, which result from the reduced perpendicular demagnetizing field, are possibly two major factors that contribute to the ultrafast STT switching.
Large memory window and good retention characteristics of ferroelectric-gate field-effect transistor with Pt/Bi3.4Ce0.6Ti3O12/CeO2/Si structure
Authors: Jiang Bo , Tang Minghua , Li Jiancheng , Xiao Yongguang , Tang Zhenhua , Cai Haiquan , Lv Xiaosong , Zhou Yichun
Published: December 2011

Bi4−x
Ce
x
Ti3 O12(x = 0.0, 0.4, 0.6 and 1.0) ferroelectric-thin films were fabricated by chemical solution deposition. Among these thin film samples, Bi3.4Ce0.6Ti3O12 (BCT) exhibits the best ferroelectric property. An n-channel metal–ferroelectric–insulator–silicon (MFIS) ferroelectric-gate field-effect transistor (FeFET) with Pt/BCT/CeO2/Si structure was fabricated and characterized. Due to the relatively good interface properties between the insulator layer (CeO2) and ferroelectric-gate layer (BCT), the device shows a nearly unchanged memory window of about 3.2 V after a 24 h retention test and a field-effect mobility of approximately 24.6 cm2 V−1 s−1. These results suggest that the Pt/BCT/CeO2/Si FeFET is suitable for high-performance ferroelectric memory application.