bluuebunny/crossref_metadata_2025 huggingface dataset:
Trypanosoma cruzi nucleoside diphosphate kinase 1 (TcNDPK1) has a broad nuclease activity
Authors: MIRANDA M. R. , CANEPA G. E. , BOUVIER L. A. , PEREIRA C. A.
Published: November 2008

Here, we present the characterization of a trypanosomatid nucleoside diphosphate kinase (TcNDPK1) exhibiting nuclease activity. This is the first identification of a NDPK with this property in trypanosomatid organisms. The recombinant TcNDPK1 protein cleaves not only linear DNA, but also supercoiled plasmid DNA. Additionally, TcNDPK1 is capable of degrading Trypanosoma cruzi genomic DNA. ATP or ADP did not affect the nuclease activity, while the absence of Mg2+ completely inhibits this activity. NDPK and nuclease activities were inhibited at the same temperature, suggesting the presence of related catalytic sites. Furthermore, phenogram analysis showed that TcNDPK1 is close to Drosophila melanogaster and human NDPKs. The unspecific nuclease activity could suggest a participation in cellular processes such as programmed cell death.
Interactive question answering and constraint relaxation in spoken dialogue systems
Authors: VARGES S. , WENG F. , PON-BARRY H.
Published: November 2008

We explore the relationship between question answering and constraint relaxation in spoken dialogue systems and develop dialogue strategies for selecting and presenting information succinctly. In particular, we describe methods for dealing with the results of database queries in information-seeking dialogues. Our goal is to structure the dialogue in such a way that the user is neither overwhelmed with information nor left uncertain as to how to refine the query further. We present two sets of evaluation results for a restaurant selection task: one is a system performance evaluation experiment involving twenty subjects, the other is an experimental evaluation of the use of suggestions involving sixteen subjects.
Composition in circular sound space: Migration 12-channel electronic music (1995–97)
Authors: Chagas Paulo C
Published: November 2008

How does production and spatial environment shape the aesthetics of electroacoustic music? Can the physical space, technology and network of relationships associated with studio activities environment be deeply embedded in the actual composition itself? Using my 12-channel electronic piece Migration as an example, this article demonstrates how the ‘materiality’ of the former Studio für Elektronische Musik of the WDR Radio, Cologne, Germany influenced the conception of ‘circular sound space’. Space in electroacoustic music is considered as embodiment of gestural experience driven by performance and composition. The discussion gives insights into the development of circular approaches of sound space in relationship to analogue and digital machinery. Particular attention is paid to the correlation between sound synthesis and sound space as a structuring principle of multi-channel electroacoustic music composition.
Technological implications of Phill Niblock's drone music, derived from analytical observations of selected works for cello and string quartet on tape
Authors: Straebel Volker
Published: November 2008

Four compositions for cello and string quartet on tape by American intermedia artist Phill Niblock originating from 1974 to 2003 are discussed. The interdependence of compositional approach and available technology is considered, leading to the observation that the electronic music composer's technique is considerably independent of the available technology. Where a dependence of artistic development on factors not originally musical has to be acknowledged, these nonmusical factors lie not so much in the technology but in Niblock's interpretation of it. This is discussed within the context of philosophical observations on art and technology by Theodor W. Adorno, Martin Heidegger and Ernst Cassirer.
Abdominal obesity and the prevalence of diabetes and intermediate hyperglycaemia in Chinese adults
Authors: He Yuna , Zhai Fengying , Ma Guansheng , Feskens Edith JM , Zhang Jian , Fu Ping , Van’t Veer Pieter , Yang Xiaoguang
Published: November 2008

Objective

To assess the association of indicators of general and abdominal obesity with the prevalence of type 2 diabetes (T2DM) and intermediate hyperglycaemia (IHG) in the Chinese population.

Methods

We used data of 50 905 adults aged 18–79 years in the 2002 China National Nutrition and Health Survey. Recommended Chinese cut-off values were used for BMI (24 kg/m2) and waist circumference (WC; 85 cm in men, 80 cm in women). Optimal cut-offs for waist:height ratio (WHtR) were determined from analyses of receiver-operating characteristic (ROC) curves.

Results

The prevalence of T2DM and IHG was 2·6 % and 1·9 % respectively. ROC curve analyses indicated 0·5 as the optimal cut-off value for WHtR in both sexes. High BMI, WC and WHtR were all associated with the prevalence of glucose tolerance abnormalities, with the highest prevalence ratio (PR) for high WHtR (men: PR = 2·85, 95 % CI 2·54, 3·21; women: PR = 3·10, 95 % CI 2·74, 3·51). When combining BMI and WHtR, in men either a high BMI or a high WHtR alone was associated with increased risk. Among women, a high BMI without a concomitant high WHtR was not associated with increased glucose tolerance abnormalities risk, whereas a high WHtR was associated with risk irrespective of BMI.

Conclusions

Among the Chinese adult population measures of central obesity are better predictors of glucose tolerance abnormalities prevalence than BMI. A WHtR cut-off point of 0·5 for both men and women can be considered as optimum for predicting (pre-) diabetes and may be a useful tool for screening and health education.
In-Depth Fluorescence Lifetime Imaging Analysis Revealing SNAP25A-Rabphilin 3A Interactions
Authors: Lee Jiung-De , Huang Ping-Chun , Lin Yi-Cheng , Kao Lung-Sen , Huang Chien-Chang , Kao Fu-Jen , Lin Chung-Chih , Yang De-Ming
Published: November 2008

The high sensitivity and spatial resolution enabled by two-photon excitation fluorescence lifetime imaging microscopy/fluorescence resonance energy transfer (2PE-FLIM/FRET) provide an effective approach that reveals protein-protein interactions in a single cell during stimulated exocytosis. Enhanced green fluorescence protein (EGFP)–labeled synaptosomal associated protein of 25 kDa (SNAP25A) and red fluorescence protein (mRFP)–labeled Rabphillin 3A (RPH3A) were co-expressed in PC12 cells as the FRET donor and acceptor, respectively. The FLIM images of EGFP-SNAP25A suggested that SNAP25A/RPH3A interaction was increased during exocytosis. In addition, the multidimensional (three-dimensional with time) nature of the 2PE-FLIM image datasets can also resolve the protein interactions in the z direction, and we have compared several image analysis methods to extract more accurate and detailed information from the FLIM images. Fluorescence lifetime was fitted by using one and two component analysis. The lifetime FRET efficiency was calculated by the peak lifetime (τpeak) and the left side of the half-peak width (τ1/2), respectively. The results show that FRET efficiency increased at cell surface, which suggests that SNAP25A/RPH3A interactions take place at cell surface during stimulated exocytosis. In summary, we have demonstrated that the 2PE-FLIM/FRET technique is a powerful tool to reveal dynamic SNAP25A/RPH3A interactions in single neuroendocrine cells.
A Method for Chronological Intravital Imaging of Bovine Oocytes duringIn VitroMaturation
Authors: Petersen Morten R. , Hansen Michael , Avery Birthe , Bøgh Ingrid B.
Published: November 2008

Oocyte maturation is known to affect the chances for successful fertilization, embryonic development, establishment of pregnancy and delivery of a live, healthy, and viable offspring. Two-photon laser scanning microscopy (TPLSM) has previously been used to evaluate early embryonic development without a detectable impairment of subsequent development, but has never been applied to assess mammalian oocytes throughoutin vitromaturation (IVM). Visualization of structures within live oocytes during IVM, followed by fertilization and embryo culture, may improve the understanding of oocyte maturation. To visualize structures within bovine oocytes using TPLSM, it is necessary to remove the cumulus cells that normally surround the oocyte during maturation. Repeated visualization of structures within the same oocyte is possible, if movement of the oocyte can be avoided. In this article, we describe the development of a method for repeated intravital imaging of denuded bovine oocytes using an upright TPLSM equipped with a specially constructed incubator. Oocytes were stained with Hoechst 33258, and the nuclear structures were evaluated. Oocyte fertilization rate was not affected by TPLSM exposure, but the developmental capacity of the denuded oocytes was significantly reduced. This is, to our knowledge, the first article describing repeated intravital imaging during mammalian oocyte maturation using TPLSM.
Nonlinear Optical Imaging of Cellular Processes in Breast Cancer
Authors: Provenzano Paolo P. , Eliceiri Kevin W. , Yan Long , Ada-Nguema Aude , Conklin Matthew W. , Inman David R. , Keely Patricia J.
Published: November 2008

Nonlinear optical imaging techniques such as multiphoton and second harmonic generation (SHG) microscopy used in conjunction with novel signal analysis techniques such as spectroscopic and fluorescence excited state lifetime detection have begun to be used widely for biological studies. This is largely due to their promise to noninvasively monitor the intracellular processes of a cell together with the cell's interaction with its microenvironment. Compared to other optical methods these modalities provide superior depth penetration and viability and have the additional advantage in that they are compatible technologies that can be applied simultaneously. Therefore, application of these nonlinear optical approaches to the study of breast cancer holds particular promise as these techniques can be used to image exogeneous fluorophores such as green fluorescent protein as well as intrinsic signals such as SHG from collagen and endogenous fluorescence from nicotinamide adenine dinucleotide or flavin adenine dinucleotide. In this article the application of multiphoton excitation, SHG, and fluorescence lifetime imaging microscopy to relevant issues regarding the tumor-stromal interaction, cellular metabolism, and cell signaling in breast cancer is described. Furthermore, the ability to record and monitor the intrinsic fluorescence and SHG signals provides a unique tool for researchers to understand key events in cancer progression in its natural context.
The road to the Industrial Revolution: hypotheses and conjectures about the medieval origins of the ‘European Miracle’
Authors: van Zanden Jan Luiten
Published: November 2008

The article uses various ways of measuring the efficiency of institutions regulating market exchange, such as interest rates, the skill premium, and the level of market integration, to try to answer the question about the quality of institutions in the different parts of Eurasia in the centuries before the ‘Great Divergence’. It appears that Western Europe, from as early as the late medieval period, had a relatively well-developed set of institutions. By contrast, South and Southeast Asian institutions were much less geared towards well-functioning markets. However, Japan and China in the seventeenth and eighteenth centuries developed institutions that were relatively efficient, and resulted in relatively high levels of commercial exchange. A number of hypotheses are then reviewed that may help to explain a European head start dating from the late Middle Ages.
Bullying and Suicide Attempts Among Adolescents Kept in Custody
Authors: Kiriakidis Stavros P.
Published: November 2008

This contribution explores the associations between suicide attempts; bullying; and the familial, educational, legal, and institutional characteristics of young offenders in custody. The sample was 152 randomly selected male young offenders aged 16–21 years (M = 18.9, SD = 1.3) years from the largest young offenders institution in Scotland, who completed structured personal interviews. Rates of reported suicide attempts were significantly higher in the population of young offenders than reported rates from general population samples. Being in residential care, the presence of a social worker for the family, family history of alcohol abuse, family history of suicide attempts, the experience of being bullied in custody, contact with a psychologist in the community, and being a violent offender were significantly related to increased risk of suicide attempts in custody. Compared to those who were not bullied, offenders who were bullied in custody were 9.22 times more likely to attempt suicide. The implications these findings for reducing bullying in penal settings are discussed.
The variation of large‐magnitude volcanic ash cloud formation with source latitude
Authors: Baines Peter G. , Jones Morgan T. , Sparks R. Stephen J.
Published: November 2008

Very large magnitudes of explosive volcanic eruptions can produce giant ash clouds with diameters of hundreds to thousands of kilometers. These ash clouds are controlled by gravity and rotational forces, leading to a more radially constrained shape than clouds produced by smaller eruptions. Here we develop a dynamic model of the formation of large ash clouds that are produced by eruptions of constant intensity and finite duration, incorporating source latitude, eruption type, magnitude, and intensity. The cloud grows as a stratified intrusion in the stratosphere to an equilibrium shape that approximates an ellipsoid of revolution, rotating anticyclonically as a solid body, at sufficient large distances from the equator. More generally, the structure of the cloud is determined by the source latitude λs and the parameter Ys = ys(β/Nd0)1/2, wherein ys is the distance of the source from the equator, β is the north‐south gradient of the Coriolis frequency, N is the buoyancy frequency of the stratosphere, and d0 is the maximum cloud thickness. A steady solution for an equilibrium cloud exists if Ys lies above a boundary that ranges from π/2 at the equator to 0 at the pole. These clouds move westward at an increasing rate with decreasing latitude. Below this boundary steady solutions appear not to exist and the nature of the breakdown of the solution at the boundary suggests that the cloud, or part of it, moves toward and across the equator. The above parameters may be expressed in terms of latitude and cloud volume, which enables the model to be applied to the ash clouds of past large‐magnitude eruptions. The results suggest that the behavior of clouds formed from plinian phases with eruption magnitudes M < 6.5 (M = log10m − 7, wherein m is the erupted mass in kilograms) depends on source latitude and eruption intensity, whereas for M > 6.5 they could achieve interhemispheric transport from most latitudes. For clouds from co‐ignimbrite sources, for M < 7.5, cross‐equatorial transport is only possible for sources in the tropics, but for M > 8, it is possible from most latitudes.
Periglacial landforms at the Phoenix landing site and the northern plains of Mars
Authors: Mellon Michael T. , Arvidson Raymond E. , Marlow Jeffrey J. , Phillips Roger J. , Asphaug Erik
Published: November 2008

We examine potentially periglacial landforms in Mars Orbiter Camera (MOC) and High Resolution Imaging Science Experiment (HiRISE) images at the Phoenix landing site and compare them with numerical models of permafrost processes to better understand the origin, nature, and history of the permafrost and the surface of the northern plains of Mars. Small‐scale (3–6 m) polygonal‐patterned ground is ubiquitous throughout the Phoenix landing site and northern plains. Larger‐scale (20–25 m) polygonal patterns and regularly spaced (20–35 m) rubble piles (localized collections of rocks and boulders) are also common. Rubble piles were previously identified as “basketball terrain” in MOC images. The small polygon networks exhibit well‐developed and relatively undegraded morphology, and they overlay all other landforms. Comparison of the small polygons with a numerical model shows that their size is consistent with a thermal contraction origin on current‐day Mars and are likely active. In addition, the observed polygon size is consistent with a subsurface rheology of ice‐cemented soil on depth scales of about 10 m. The size and morphology of the larger polygonal patterns and rubble piles indicate a past episode of polygon formation and rock sorting in thermal contraction polygons, while the ice table was about twice as deep as it is presently. The pervasive nature of small and large polygons, and the extensive sorting of surface rocks, indicates that widespread overturning of the surface layer to depths of many meters has occurred in the recent geologic past. This periglacial reworking has had a significant influence on the landscape at the Phoenix landing site and over the Martian northern plains.
Observations of wind‐blown sand under various meteorological conditions at a beach
Authors: Udo Keiko , Kuriyama Yoshiaki , Jackson Derek W. T.
Published: November 2008

Field observations were conducted on a natural, open ocean beach system in Japan to investigate characteristics of wind‐blown sand transport under various weather conditions including a storm event. Data sets over periods of several hours included blown sand impact counts, three‐dimensional wind conditions, hourly precipitation, and moisture content of the sediment surface. The intermittent blown sand impact data shifted by 1 s ahead of the wind velocity correlated with the wind velocity during a no‐rainfall period (for an assumed dry surface) and in the longshore wind direction (for sufficiently long fetch length). The 5‐min mean wind velocity/impact counts relationship was well constrained by both second‐ and third‐order polynomial fitting of velocity under similar weather conditions. During a no‐rainfall period and in the longshore wind direction, the relationship between the wind velocity and sand flux estimated from the counts coincides with existing studies in wind tunnel experiments. The sand flux, however, decreased by 1 order of magnitude because of a change in the wind direction from longshore to cross‐shore and then by more than 1 order of magnitude because of an increase in the moisture content. Threshold wind velocity calculated using the time fraction equivalence method with the impact counts and the horizontal wind velocity in 5‐min sampling periods was approximately equal to the value predicted using Bagnold's equation during the no‐rainfall period and increased significantly during the rainfall phase. The sand flux sensor has several limitations for complex conditions in the field; however, it provides a number of characteristics of sand transport under various meteorological conditions.
Marine isotope stage 3 sea level fluctuations: Data synthesis and new outlook
Authors: Siddall M. , Rohling E. J. , Thompson W. G. , Waelbroeck C.
Published: November 2008

To develop a better understanding of the abrupt Dansgaard‐Oeschger mode of climate change, it is essential that we establish whether the ice sheets are actively involved, as trigger or amplifier, or whether they merely respond in a passive manner. This requires careful assessment of the fundamental issues of magnitude and phasing of global ice volume fluctuations within marine isotope stage 3 (MIS 3), which to date remain enigmatic. We review recent advances in observational studies pertaining to these key issues and discuss the implications for modeling studies. Our aim is to construct a robust stratigraphic framework for the MIS 3 period regarding sea level variability, using the most up‐to‐date arguments available by combining insights from both modeling and observational approaches.
Statistical properties of fresh snow roughness
Authors: Manes C. , Guala M. , Löwe H. , Bartlett S. , Egli L. , Lehning M.
Published: November 2008

We present results from a series of experiments in which fresh snow roughness was measured by means of digital photography and analyzed using the random field approach. The aim of the paper is to investigate the scaling properties of fresh‐snow‐covered surfaces and to capture key roughness length scales which can characterize the surface geometry and the size of the snow crystals. Results from our experiments show the following: (1) fresh snow roughness exhibits two distinguished scaling regimes, one at scales comparable with the crystals size and another one at larger scales; (2) we confirm that the large scales are built up during snowfall and their scaling behavior is consistent with that of Ballistic Deposition (BD) processes; and (3) we suggest that the crossover length scale separating the two scaling regimes effectively defines a representative length scale of the aggregated snow crystals on the surface. The definition of this length scale is independent of the difficulties associated with measuring snow grain sizes by means of standard microscopic analysis of disaggregated crystals. Furthermore it can be obtained from a low‐cost and quick experimental procedure. Results from this study provide a plausible justification for the wide scatter of aerodynamic roughness length values encountered in the literature for fresh snow. Moreover, they provide insight on the key roughness length scales which should be used for the modeling of this parameter.
Navigational infrastructure at the East Pacific Rise 9°50′N area following the 2005–2006 eruption: Seafloor benchmarks and near‐bottom multibeam surveys
Authors: Soule S. A. , Ferrini V. L. , Kinsey J. C. , Fornari D. J. , Sellers C. , White S. M. , Von Damm K. , Carbotte S. M.
Published: November 2008

Four seafloor benchmarks were deployed with ROV Jason2 at frequently visited areas along the northern East Pacific Rise (NEPR) ridge crest near 9°50′N, within the Ridge2000 EPR integrated study site (ISS) bull's eye. When used in concert with established deep‐ocean acoustic positioning techniques, these benchmarks provide navigational infrastructure to facilitate the integration of near‐bottom data at this site by allowing efficient and quantitative coregistration of data and observations collected on multiple dives and over multiple cruises. High‐resolution, near‐bottom multibeam bathymetric surveys also were conducted along and across the ridge crest to provide a morphological and geological context for the benchmark areas. We describe the navigation and data processing techniques used to constrain the benchmark positions and outline operational details to effectively use benchmarks at this and other deep‐ocean sites where multidisciplinary time series studies are conducted. The well‐constrained positions of the benchmarks provide a consistent geospatial framework that can be used to limit navigational uncertainties during seafloor sampling and mapping programs and enable accurate spatial coregistration and integration of observations. These data are important to test a range of multidisciplinary hypotheses that seek to link geological, chemical, and biological processes associated with crustal accretion and energy transfer from the mantle to the hydrosphere at mid‐ocean ridges.
Coastal Southern Ocean: A strong anthropogenic CO2 sink
Authors: Arrigo Kevin R. , van Dijken Gert , Long Matthew
Published: November 2008

Large‐scale estimates of the Southern Ocean CO2 sink do not adequately resolve the fluxes associated with Antarctic continental shelves. Using a mechanistic three‐dimensional biogeochemical model of the Ross Sea, we show that Antarctic shelf waters are a strong sink for CO2 due to high biological productivity, intense winds, high ventilation rates, and extensive winter sea ice cover. Net primary production (NPP) in these waters is ∼0.055 Pg C yr−1. Some of this carbon sinks to depth, driving an influx of CO2 of 20–50 g C m−2 yr−1. Although currently unaccounted for, the total atmospheric CO2 sink on the Ross Sea continental shelf of 0.013 Pg C yr−1 is equivalent to 27% of the most recent estimate of the CO2 sink for the entire Southern Ocean. Given these results, these and other highly productive waters around the Antarctic continent need to be included in future budgets of anthropogenic CO2.
Statistics of velocity fluctuations observed by SuperDARN under steady interplanetary magnetic field conditions
Authors: Bristow William
Published: November 2008

A study of velocity fluctuations observed by the Super Dual Auroral Radar Network (SuperDARN) HF radar network is presented. The study was undertaken with the goals of determining the level of fluctuation due to internal magnetospheric processes, and to examine the probability of observing a significant velocity fluctuation within any given time interval. The study included 6 years of observations from periods when the interplanetary magnetic field (IMF) was moderately southward and steady. It was assumed that the IMF that encounters the magnetosphere is the same as that observed at a spacecraft located upstream from the Earth and that all variability of the plasma convection is due either to variability of the IMF driver or to internal magnetospheric processes. IMF variability away from the satellite was examined statistically by comparing the distributions of observations for the ACE and Wind satellites. The distribution of velocity fluctuations and their waiting time distribution were examined over a grid of latitude and local time. It was found that the waiting time is scale free over the range of times that could be examined. From the waiting time distributions, the probability of observing fluctuations within various time intervals was determined over the grid. It was found that the probability of observing a significant velocity fluctuation is high for all local times in the high‐latitude region.
Geocoronal hydrogen observations spanning three solar minima
Authors: Nossal S. M. , Mierkiewicz E. J. , Roesler F. L. , Haffner L. M. , Reynolds R. J. , Woodward R. C.
Published: November 2008

The 11‐year solar cycle is a dominant source of natural variability in the upper atmosphere, and its effect on atomic hydrogen distributions and emissions must be understood to investigate possible signs of longer‐term climatic trends in this region. We present midlatitude geocoronal hydrogen Balmer α observations from solar cycle 23 (1997–2006) and three solar minimum periods, 1985, 1997, and 2006. The 1997 through 2006 observations were taken with the Wisconsin H‐α Mapper Fabry‐Perot (WHAM), a ground‐based CCD‐annular summing instrument that began observations at the Kitt Peak Observatory in Arizona in 1997. The 1985 observations were made with a similarly designed “pre‐WHAM” Fabry‐Perot Interferometer utilizing photomultiplier detection and located in Wisconsin. WHAM has consistently observed higher column emission intensities during solar maximum periods than during solar minimum conditions, with the ratio dependent upon the viewing geometry. The observations from three solar minimum periods agree to within 18% uncertainties over most of the shadow altitude range. An analysis of recent Fabry‐Perot observations of upper atmospheric hydrogen during solar cycle 23 and during three solar minima (1985, 1997, 2006) established a reference data set of highly precise, consistently calibrated, thermospheric plus exospheric hydrogen column emission observations from northern midlatitudes that can be used to compare with future observations.
Is an unusual large enhancement of ionospheric electron density linked with the 2008 great Wenchuan earthquake?
Authors: Zhao Biqiang , Wang Min , Yu Tao , Wan Weixing , Lei Jiuhou , Liu Libo , Ning Baiqi
Published: November 2008

On 12 May 2008 at 0628 UT a major earthquake Ms = 8.0 struck Wenchuan County (31.0°N, 103.4°E) in southwest China. The maximum ionospheric electron density at F2 peak (NmF2) recorded an unusual large enhancement during the afternoon‐sunset sector by the Chinese ionosondes over Wuhan (30.5°N, 114.4°E) and Xiamen (24.4°N, 123.9°E), which are close to the earthquake epicenter. An averaged increase at these two stations is about 2 times on a geomagnetic quiet day, 9 May (Kp ≤ 2), 3 days prior to the earthquake, relative to the median value of 1–12 May, whereas the increase was much less significant over Yamagawa (31.2°N, 130.6°E) and Okinawa (26.7°N, 128.2°E) in Japan. Combining the data from the network of 58 global positioning system receivers around China and the global ionospheric map, the variations of the total electron content reveal the region where enhancement persisted for a long period to be within longitudes 90°–130°E. Our results suggest that this abnormal enhancement is most possibly a seismo‐ionospheric signature.
Observed instantaneous cirrus radiative effect on surface‐level shortwave and longwave irradiances
Authors: Dupont Jean‐Charles , Haeffelin Martial
Published: November 2008

Data collected at the SIRTA Observatory, 20 km south of Paris, are analyzed to determine the instantaneous surface cloud radiative effect (CRE) induced by cirrus clouds. CRE is here defined as the difference between overcast‐sky and clear‐sky surface radiative fluxes obtained by ground‐based measurement of broadband fluxes and clear‐sky parametric models, respectively. Clear‐sky periods detected by a double threshold based on lidar and radiative fluxes analysis show a root mean square error for clear‐sky models smaller than 6.5 W m−2 for shortwave flux and 4 W m−2 for longwave flux. Over 100 h in 2003–2006 characterized by homogeneous overcast cirrus clouds are analyzed. Fifty percent of this cirrus population is subvisible and semitransparent, that is, with optical thickness less than 0.3. The mean surface shortwave cirrus cloud radiative effect (CRESW) is found near −50 W m−2. We establish the relationship between CRESW and cirrus optical thickness (COT) to be about −90 W m−2 per unit of COT. This SW sensitivity ranges from −80 W m−2 COT−1 to −100 W m−2 COT−1 for turbid to pristine atmospheres, respectively. We also establish the relationship between surface longwave cloud radiative effect (CRELW) and the irradiance emitted by the cirrus cloud derived from cloud infrared emissivity and cloud temperature. The average surface CRELW is about +5 W m−2. CRELW is found to be about 10% of the cloud irradiance. This LW effect ranges from 5 to 15% of the cirrus irradiance depending on atmospheric humidity for the wet and dry atmosphere, respectively.
Absorbing aerosols over Asia: A Geophysical Fluid Dynamics Laboratory general circulation model sensitivity study of model response to aerosol optical depth and aerosol absorption
Authors: Randles C. A. , Ramaswamy V.
Published: November 2008

Forcing by absorbing atmospheric black carbon (BC) tends to heat the atmosphere, cool the surface, and reduce the surface latent and sensible heat fluxes. BC aerosol can have a large impact on regional climates and the hydrologic cycle. However, significant uncertainties remain concerning the increases in (1) the total amount of all aerosol species and (2) the amount of aerosol absorption that may have occurred over the 1950–1990 period. Focusing on south and east Asia, the sensitivity of a general circulation model's climate response (with prescribed sea surface temperatures and aerosol distributions) to such changes is investigated by considering a range of both aerosol absorption and aerosol extinction optical depth increases. We include direct and semidirect aerosol effects only. Precipitation changes are less sensitive to changes in aerosol absorption optical depth at lower aerosol loadings. At higher‐extinction optical depths, low‐level convergence and increases in vertical velocity overcome the stabilizing effects of absorbing aerosols and enhance the monsoonal circulation and precipitation in northwestern India. In contrast, the presence of increases in only scattering aerosols weakens the monsoonal circulation and inhibits precipitation here. Cloud amount changes can enhance or counteract surface solar flux reduction depending on the aerosol loading and absorption, with the changes also influencing the surface temperature and the surface energy balance. The results have implications for aerosol reduction strategies in the future that seek to mitigate air pollution concerns. At higher optical depths, if absorbing aerosol is present, reduction of scattering aerosol alone has a reduced effect on precipitation changes, implying that reductions in BC aerosols should be undertaken at the same time as reductions in sulfate aerosols.
Changes in the seasonality of precipitation over the contiguous USA
Authors: Pryor S. C. , Schoof J. T.
Published: November 2008

Consequences of possible changes in annual total precipitation are dictated, in part, by the timing of precipitation events and changes therein. Herein, we investigated historical changes in precipitation seasonality over the US using observed station precipitation records to compute a standard seasonality index (SI) and the day of year on which certain percentiles of the annual total precipitation were achieved (percentile day of year). The mean SI from the majority of stations exhibited no difference in 1971–2000 relative to 30‐year periods earlier in the century. However, analysis of the day of year on which certain percentiles of annual total precipitation were achieved indicated spatially coherent patterns of change. In some regions, the mean day of the year on which the 50th percentile of annual precipitation was achieved differed by 20–30 days between 1971–2000 and both 1911–1940 and 1941–1970. Output from the 10‐Atmosphere‐Ocean General Circulation Models (AOGCM) simulations of 1971–2000, 2046–2065, and 2081–2100 was used to determine whether AOGCMs are capable of representing the seasonal distribution of precipitation and to examine possible future changes. Many of the AOGCMs qualitatively captured spatial patterns of seasonality during 1971–2000, but there was considerable divergence between AOGCMs in terms of future changes. In both the west and southeast, 7 of 10 AOGCMs indicated later attainment of the 50th percentile accumulation in 2047–2065, implying a possible reversal of the twentieth‐century tendency toward relative increases in precipitation receipt during winter and early spring over the southeast. However, this is also a region characterized by considerable interannual variability in the percentile day of year during the historical period.
West African Monsoon observed with ground‐based GPS receivers during African Monsoon Multidisciplinary Analysis (AMMA)
Authors: Bock O. , Bouin M. N. , Doerflinger E. , Collard P. , Masson F. , Meynadier R. , Nahmani S. , Koité M. , Gaptia Lawan Balawan K. , Didé F. , Ouedraogo D. , Pokperlaar S. , Ngamini J.‐B. , Lafore J. P. , Janicot S. , Guichard F. , Nuret M.
Published: November 2008

A ground‐based GPS network has been established over West Africa in the framework of African Monsoon Multidisciplinary Analysis (AMMA) in tight cooperation between French and African institutes. The experimental setup is described and preliminary highlights are given for different applications using these data. Precipitable water vapor (PWV) estimates from GPS are used for evaluating numerical weather prediction (NWP) models and radiosonde humidity data. Systematic tendency errors in model forecasts are evidenced. Correlated biases in NWP model analyses and radiosonde data are evidenced also, which emphasize the importance of radiosonde humidity data in this region. PWV and precipitation are tightly correlated at seasonal and intraseasonal timescales. Almost no precipitation occurs when PWV is smaller than 30 kg m−2. This limit in PWV also coincides well with the location of the intertropical discontinuity. Five distinct phases in the monsoon season are determined from the GPS PWV, which correspond either to transition or stationary periods of the West African Monsoon system. They may serve as a basis for characterizing interannual variability. Significant oscillations in PWV are observed with 10‐ to 15‐day and 15‐ to 20‐day periods, which suggest a strong impact of atmospheric circulation on moisture and precipitation. The presence of a diurnal cycle oscillation in PWV with marked seasonal evolutions is found. This oscillation involves namely different phasing of moisture fluxes in different layers implying the low‐level jet, the return flow, and the African Easterly Jet. The broad range of timescales observed with the GPS systems shows a high potential for investigating many atmospheric processes of the West African Monsoon.
Tyrrhena Patera: Geologic history derived from Mars Express High Resolution Stereo Camera
Authors: Williams David A. , Greeley Ronald , Werner Stephanie C. , Michael Greg , Crown David A. , Neukum Gerhard , Raitala Jouko
Published: November 2008

We used Mars Express High Resolution Stereo Camera images of the Tyrrhena Patera volcano to assign cratering model ages to material units defined in the VikingOrbiter‐based geologic mapping. Cratering model ages are generally consistent with their stratigraphy. We can identify three key intervals of major activity at Tyrrhena Patera: (1) formation of the volcanic edifice in the Noachian Period, ∼3.7–4.0 Ga, shortly following the Hellas impact (∼4 Ga) and coincident with the formation of Hadriaca Patera (∼3.9 Ga); (2) modification of the edifice and formation of the caldera rille and channels in the Hesperian Period, possibly extending into the Amazonian Period; and (3) a final stage of modification in the Late Amazonian Epoch, ∼0.8–1.4 Ga. Early‐ to mid‐Hesperian activity on Tyrrhena Patera is consistent with similar activity on Hadriaca Patera at ∼3.3–3.7 Ga. The most recent dateable event on Tyrrhena Patera is modification on the upper shield, caldera rille, and channel floors at ∼800 Ma. This coincidence of resurfacing in three units suggests a widespread process(es), which we speculate involved preferential (aeolian?) erosion of small craters on these flatter surfaces relative to the other units on the volcano. Alternatively, some combination of pyroclastic flow emplacement on the upper shield and fluvial activity in the caldera rille and channels, followed by differential aeolian erosion and deposition, could have produced the present surface. Regardless, major geologic resurfacing ended at Tyrrhena Patera nearly a billion years ago.
Laboratory impact experiments and numerical simulations on shock pressure attenuation in water ice
Authors: Shirai Kei , Kato Manabu , Mitani Noriko K. , Arakawa Masahiko
Published: November 2008

High‐velocity impact experiments of water ice were conducted to measure the shock pressure profile at various distances from the impact point. A numerical simulation of shock wave propagation in water ice was also conducted for comparison with the experimental results. The numerical model was improved to fit the measured profiles, and it was found that a tensile strength of Yc = 1 MPa was necessary to reproduce the shock pressure profiles above the Hugoniot Elastic Limit. This improved numerical model was then used to study the shock pressure attenuation in water ice at various impact conditions and to refine the crater scaling law. The late‐stage effective energy (LE) is the product of initial shock pressure (P0) and the third power of the projectile size (Lp3). The impact conditions with the same late‐stage effective energy can produce the same shock pressure distribution far from the impact point (so‐called late‐stage equivalence). These impact conditions were investigated by numerical calculations with different projectiles and impact velocities. As a result of our calculation for water ice impacts, we found that a power law index of 2.2 instead of 3, as adopted by previous studies, is suitable for reproducing the late‐stage equivalence in water ice (i.e., LE is proportional to P0 · Lp2.2). By using this improved LE, we can reconcile the inconsistency between the crater size and the LE indicated by previous studies. By using this improved LE, the crater volume Vcr formed on water ice is expressed by the following equation, Vcr = 1.0 exp (ln/2450), with Vcr in cm3, wherein ln (in Pa m2.2) is a constant derived from a fit to the data.
Photochemical instability of the ancient Martian atmosphere
Authors: Zahnle Kevin , Haberle Robert M. , Catling David C. , Kasting James F.
Published: November 2008

We develop a 1‐D steady state photochemical model of the modern Martian atmosphere and apply it to possible Martian atmospheres present and past. A unique feature of our model is that the major current sink of oxygen is dry deposition (surface reactions) of highly reactive, oxidized molecules (chiefly H2O2), rather than oxygen escape to space. Another difference is that we allow hydrogen to escape to space at the diffusion limit, which gives H escape fluxes ∼70% higher than in other models. What results is a model with one free parameter: a dry deposition velocity to describe the surface sink of reactive molecules. An effective global average deposition velocity of 0.02 cm s−1 for H2O2 and O3 gives a good match to the observed abundances of O2, CO, and H2, the three abundant photochemical trace gases. We then apply our model to Martian atmospheres with different amounts of CO2, H2O, and solar forcing. We find that thick, cold, dry CO2 atmospheres are photochemically unstable with respect to conversion to CO. This may be pertinent to ancient Mars when the Sun was faint and O escape rates were likely high, for which the tipping point is computed to be ∼10 mbar of CO2. The possible photochemical instability of cold thick CO2 atmospheres, and the high likelihood that CO was abundant even if CO2 were stable, has broad implications for early Mars.
Evidence for the dynamics of Acyl homoserine lactone and AHL-producing bacteria during subtidal biofilm formation
Authors: Huang Yi-Li , Ki Jang-Seu , Lee On On , Qian Pei-Yuan
Published: November 2008

The quorum sensing signals—acyl homoserine lactones (AHLs) were directly detected in 1-9-day-old subtidal biofilms developed in a coastal fish farm by using AHL reporter strains and gas chromatography–mass spectrometry. Both methods showed that the AHL molecules and/or AHL-producing bacterial community were dynamic during biofilm development, with dominant AHLs changed from short-chain to long-chain AHLs. Terminal restriction fragment length polymorphism analysis of the bacterial 16S rRNA genes derived from subtidal biofilms of different ages was compared to that of the 21 AHL-producing bacteria isolated from the same batch of subtidal biofilms. All terminal restriction fragments (TRFs) generated from AHL-producing bacteria matched with the dominant TRFs derived from the biofilm bacterial community samples. Particularly, the TRFs of all AHL-producing Vibrio spp. matched with the TRFs that were dominant only in 1-day-old biofilm, suggesting that AHL-producing vibrios were one of the pioneer groups during subtidal biofilm formation. We reported here for the first time the dynamics of AHLs and AHL-producing bacteria during the formation of a subtidal biofilm.
Rational Design of a Combination Medication for the Treatment of Obesity
Authors: Greenway Frank L. , Whitehouse M.J. , Guttadauria Maria , Anderson James W. , Atkinson Richard L. , Fujioka Ken , Gadde Kishore M. , Gupta Alok K. , O'Neil Patrick , Schumacher Donald , Smith Diane , Dunayevich Eduardo , Tollefson Gary D. , Weber Eckard , Cowley Michael A.
Published: November 2008

Existing obesity therapies are limited by safety concerns and modest efficacy reflecting a weight loss plateau. Here, we explore combination therapy with bupropion (BUP), a putative stimulator of melanocortin pathways, and an opioid antagonist, naltrexone (NAL), to antagonize an inhibitory feedback loop that limits sustained weight reduction. In vitro electrophysiologic experiments were conducted to determine the extent to which BUP+NAL stimulated hypothalamic pro‐opiomelanocortin (POMC) neurons in mouse brain. A subsequent study further characterized the effect of combination BUP+NAL treatment on food intake in lean and obese mice. Finally, a randomized, blinded, placebo‐controlled trial in obese adult subjects was conducted. Randomization included: BUP (300 mg) + NAL (50 mg), BUP (300 mg) + placebo (P), NAL (50 mg) + P or P+P for up to 24 weeks. BUP+NAL stimulated murine POMC neurons in vitro and caused a greater reduction in acute food intake than either monotherapy, an effect consistent with synergism. Combined BUP+NAL provided sustained weight loss without evidence of an efficacy plateau through 24 weeks of treatment. BUP+NAL completers diverged from NAL+P (P < 0.01) and P+P (P < 0.001) at week 16 and from BUP+P by week 24 (P < 0.05). The combination was also well tolerated. Translational studies indicated that BUP+NAL therapy produced synergistic weight loss which exceeded either BUP or NAL alone. These results supported the hypothesis that NAL, through blockade of β‐endorphin mediated POMC autoinhibition, prevents the classic weight loss plateau observed with monotherapies such as BUP. This novel treatment approach (BUP+NAL) holds promise for the treatment of obesity.
Obesity Reduction Black Intervention Trial (ORBIT): Six‐month Results
Authors: Stolley Melinda R. , Fitzgibbon Marian L. , Schiffer Linda , Sharp Lisa K. , Singh Vicky , Van Horn Linda , Dyer Alan
Published: November 2008

The Obesity Reduction Black Intervention Trial (ORBIT) is a randomized controlled trial designed to assess the efficacy of a culturally proficient 6‐month weight loss intervention followed by a 1‐year maintenance intervention. This article describes the results of the 6‐month weight loss intervention. Two hundred thirteen obese black women aged 30–65 years were randomized to the intervention group or a general health control group. The intervention consisted of a 6‐month culturally adapted weight loss program that targeted changes in diet and physical activity patterns. Weight, dietary intake, and physical activity were measured at baseline and 6 months. A total of 198 women (93%) completed both the baseline and postintervention assessments. Women in the intervention group lost significantly more weight than women in the control group (P < 0.001). However, weight change was variable within the intervention group, with a maximum weight loss of 19.4% of initial body weight and a maximum weight gain of 6.4% of initial body weight. Women in the intervention group also showed significant improvements in fruit intake (P < 0.01), Healthy Eating Index score (P < 0.001), and moderate (P = 0.05), and vigorous (P < 0.001) physical activity compared to women in the control group. This study demonstrates that a culturally adapted program can successfully promote weight loss in obese black women. However, average weight loss was relatively modest, and weight change varied widely within the intervention group. Further research is needed in order to develop programs that will allow more black women to achieve their weight loss goals.
Functional Consequences of the Human Leptin Receptor (LEPR) Q223R Transversion
Authors: Stratigopoulos George , LeDuc Charles A. , Matsuoka Naoki , Gutman Roee , Rausch Richard , Robertson Scott A. , Myers Martin G. , Chung Wendy K. , Chua Streamson C. , Leibel Rudolph L.
Published: November 2008

Perturbations in the functional integrity of the leptin axis are obvious candidates for mediation of altered adiposity. In a large number of genetic association studies in humans, the nonconservative LEPR Q223R allele has been inconsistently associated with adiposity. Subtle, long‐term effects of such genetic variants can be obscured by effects of the environment and other confounders that render definitive inferences difficult to reach. We directly assessed the biological effects of this variant in 129P3/J mice segregating for the humanized Lepr allele at codon 223. No effects of this allele were detected on body weight, composition, or energy expenditure in animals fed diets of varying fat content over periods as long as 235 days. In vitro, Q223R did not affect leptin signaling as reflected by activation of STAT3. We conclude that Q223R is unlikely to play a significant role in regulation of human adiposity. This approach to vetting of human allelic variation might be more widely used.