bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk factors for hospital readmission within 30 days: A new quality measure for children with sickle cell disease
Authors: Frei‐Jones Melissa J. , Field Joshua J. , DeBaun Michael R.
Published: December 2008

Background

The National Association of Children's Hospitals and Related Institutions (NACHRI) established hospital readmission within 30 days as a benchmark for quality care in children with Sickle Cell Disease (SCD). Among children with SCD, limited data exists to identify risk factors for readmission and whether they are modifiable.

Procedure

We performed a retrospective cohort study to identify risk factors for readmission. All admissions for children with SCD in a 1‐year period were reviewed; cases were defined as children with SCD readmitted within 30 days after their first admission during the study period and controls, children with SCD who were not readmitted.

Results

We identified 30 cases and 70 controls. No difference in demographic data was found between groups. The most common admission and readmission diagnosis was pain, 78 and 70%, respectively. The greatest risk factor for readmission was no outpatient hematology follow‐up within 30 days of discharge (OR 7.7, 95% CI 2.4–24.4). A diagnosis of asthma was also a risk factor for readmission (OR 2.9, 95% CI 1.2–7.3). Patients who required supplemental oxygen to maintain saturations in the normal range and were on room air for ≤24 hr at discharge were also more likely to be readmitted (OR 3.3, 95% CI 1.1–9.7). Multivariate analysis identified lack of outpatient follow‐up and disease severity, defined as ≥3 admissions in the previous 12 months as predictors for readmission (R2 = 0.41).

Conclusions

Potentially modifiable risk factors exist to decrease the rate of readmission of children with SCD admitted to the hospital for pain. Pediatr Blood Cancer 2009;52:481–485. © 2008 Wiley‐Liss, Inc.
Experimental translocation of juvenile water voles in a Scottish lowland metapopulation
Authors: Fisher Diana O. , Lambin Xavier , Yletyinen Sonja M.
Published: December 2008

Population density affects dispersal success because residents can hinder or facilitate immigration into a new site, via a “social fence effect” or “social attraction” (or “conspecific attraction”), respectively. These mechanisms can affect the dynamics of fragmented populations and the success of translocations. However, information on the settlement behaviour of dispersers is rare. We conducted a manipulative field experiment using wild water voles, which exist in metapopulations along waterways in Scotland. We translocated 17 young of dispersal age into either an occupied site or a vacant site containing good habitat, which had recently become extinct due to a feral predator (American mink) moving through. We monitored the movements of translocated voles using radio telemetry. Translocated voles were less likely to settle in occupied sites with higher densities of residents, suggesting a possible social fence effect at high density. There was evidence of a social attraction mechanism, because voles never remained at new sites unless another individual arrived soon after translocation, and they were more likely to settle in occupied or colonised sites than vacant ones. Voles remained in the transient phase of dispersal for many days, and often followed a “stepping stone” trajectory, stopping for several days at successive sites. We suggest that trajectories followed by dispersing water voles, the time scale and long dispersal distances found in this species are conducive to locating conspecifics at low density and colonising vacant habitat. These results are encouraging for prospects of metapopulation persistence and future translocation success.
Perioperative Care of the Patient with Tuberculosis
Authors: Neil Janice A.
Published: December 2008

APPROXIMATELY 1.7 BILLION PEOPLE are thought to be infected with Mycobacterium tuberculosis. The estimated mortality rate is 3 million people per year.

MULTIDRUG RESISTANT‐TUBERCULOSIS (MDR‐TB) and extensively drug‐resistant TB (XDR‐TB) are serious problems that threaten global TB control. Patients who are inadequately treated remain chronic carriers and can spread the disease to family members and their communities.

TREATMENT RECOMMENDATIONS for TB include directly observed treatment and monitoring the patient's response to medications. Perioperative nurses must protect the patient and other health care workers when a patient with TB undergoes a surgical procedure. AORN J 88 (December 2008) 942–958. © AORN, Inc, 2008.
The New Afro-Cuban Cultural Movement and the Debate on Race in Contemporary Cuba
Authors: DE LA FUENTE ALEJANDRO
Published: December 2008

This paper analyses recent debates on race and racism in Cuba in the context of changing economic and social conditions in the island. Since the early 1990s, and largely in response to the negative effects that the so-called Special Period had on race relations, a group of artists and intellectuals began denouncing the persistence of racist practices and stereotypes in Cuban society. Although they are not organised around a single program or institution, these musicians, visual artists, writers, academics and activists share common grievances about racism and its social effects. It is in this sense that they constitute a new Afro-Cuban cultural movement. It is too early to fully assess the impact of this movement, but these artists and intellectuals have been largely successful in raising awareness about this problem and bringing it to the attention of authorities and the Cuban public.
Oscillatory instabilities and dynamics of multi-spike patterns for the one-dimensional Gray-Scott model
Authors: CHEN WAN , WARD MICHAEL J.
Published: December 2008

The dynamics and oscillatory instabilities of multi-spike solutions to the one-dimensional Gray-Scott reaction–diffusion system on a finite domain are studied in a particular parameter regime. In this parameter regime, a formal singular perturbation method is used to derive a novel ODE–PDE Stefan problem, which determines the dynamics of a collection of spikes for a multi-spike pattern. This Stefan problem has moving Dirac source terms concentrated at the spike locations. For a certain subrange of the parameters, this Stefan problem is quasi-steady and an explicit set of differential-algebraic equations characterizing the spike dynamics is derived. By analysing a nonlocal eigenvalue problem, it is found that this multi-spike quasi-equilibrium solution can undergo a Hopf bifurcation leading to oscillations in the spike amplitudes on an O(1) time scale. In another subrange of the parameters, the spike motion is not quasi-steady and the full Stefan problem is solved numerically by using an appropriate discretization of the Dirac source terms. These numerical computations, together with a linearization of the Stefan problem, show that the spike layers can undergo a drift instability arising from a Hopf bifurcation. This instability leads to a time-dependent oscillatory behaviour in the spike locations.
On the Likely Number of Solutions for the Stable Marriage Problem
Authors: LENNON CRAIG , PITTEL BORIS
Published: December 2008

An instance of a size-n stable marriage problem involves n men and n women, each individually ranking all members of opposite sex in order of preference as a potential marriage partner. A complete matching, a set of n marriages, is called stable if no unmatched man and woman prefer each other to their partners in the matching. It is known that, for every instance of marriage partner preferences, there exists at least one stable matching, and that there are instances with exponentially many stable matchings. Our focus is on a random instance chosen uniformly from among all (n!)2n possible instances. The second author had proved that the expected number of stable marriages is of order nlnn, while its likely value is of order n1/2−o(1) at least. In this paper the second moment of that number is shown to be of order (nlnn)2. The combination of the two moment estimates implies that the fraction of problem instances with roughly cnlnn solutions is at least 0.84. Whether this fraction is asymptotic to 1 remains an open question.
Impact of land cover uncertainties on estimates of biospheric carbon fluxes
Authors: Quaife T. , Quegan S. , Disney M. , Lewis P. , Lomas M. , Woodward F. I.
Published: December 2008

Large‐scale bottom‐up estimates of terrestrial carbon fluxes, whether based on models or inventory, are highly dependent on the assumed land cover. Most current land cover and land cover change maps are based on satellite data and are likely to be so for the foreseeable future. However, these maps show large differences, both at the class level and when transformed into Plant Functional Types (PFTs), and these can lead to large differences in terrestrial CO2 fluxes estimated by Dynamic Vegetation Models. In this study the Sheffield Dynamic Global Vegetation Model is used. We compare PFT maps and the resulting fluxes arising from the use of widely available moderate (1 km) resolution satellite‐derived land cover maps (the Global Land Cover 2000 and several MODIS classification schemes), with fluxes calculated using a reference high (25 m) resolution land cover map specific to Great Britain (the Land Cover Map 2000). We demonstrate that uncertainty is introduced into carbon flux calculations by (1) incorrect or uncertain assignment of land cover classes to PFTs; (2) information loss at coarser resolutions; (3) difficulty in discriminating some vegetation types from satellite data. When averaged over Great Britain, modeled CO2 fluxes derived using the different 1 km resolution maps differ from estimates made using the reference map. The ranges of these differences are 254 gC m−2 a−1 in Gross Primary Production (GPP); 133 gC m−2 a−1 in Net Primary Production (NPP); and 43 gC m−2 a−1 in Net Ecosystem Production (NEP). In GPP this accounts for differences of −15.8% to 8.8%. Results for living biomass exhibit a range of 1109 gC m−2. The types of uncertainties due to land cover confusion are likely to be representative of many parts of the world, especially heterogeneous landscapes such as those found in western Europe.
Investigation of the multiple‐component structure of the 20 January 2005 cosmic ray ground level enhancement
Authors: McCracken K. G. , Moraal H. , Stoker P. H.
Published: December 2008

Worldwide observations of the cosmic ray ground level enhancement (GLE) of 20 January 2005 are used to investigate a commonly observed but poorly understood feature of this class of event. It is argued that the GLE comprised two distinctly different cosmic ray populations. The first resulted in an impulsive, highly anisotropic, field‐aligned pulse with a relatively hard rigidity spectrum and significant velocity dispersion. The characteristics of the anisotropy were almost identical to those for similar impulsive increases observed during GLEs in 1960, 1978, and 1989. The π0γ ray observations from the RHESSI and CORONAS‐F spacecraft and Type III radio emissions yield a path length of 1.76 ± 0.1 AU to Earth for the first pulse. After the highest energies in the initial anisotropic pulse had passed Earth, another field‐aligned but mildly anisotropic cosmic ray pulse developed slowly worldwide, exhibiting the characteristics of the conventional GLE. The risetime and anisotropy of this second population indicate substantial scattering, apparently at variance to the essentially scatter‐free nature of the initial pulse. We show that the coexisting scatter‐free initial impulsive increase and the diffusive character of the second pulse are consistent with the standard quasi‐linear theory of pitch angle diffusion. Throughout the GLE, the anisotropy remained field‐aligned, and a third maximum, seen by some stations, is shown to be due to changes in the direction of the heliospheric magnetic field (HMF). Examination of 22 large (>20%) GLEs in the historical record shows that the impulsive pulse never occurs after the commencement of the P2 pulse, indicating that the impulsive‐gradual combination is not due to a chance sampling of differing scattering regions of the HMF. It is further shown that impulsive pulses, or their equivalents, have been observed in 13 out of the 15 GLEs associated with solar activity in the solar longitude range 24°–98°W, leading us to propose that the event of 20 January 2005 should be regarded as the defining example of the GLE. The observations lead us to propose two separate acceleration episodes in the typical GLE: (1) acceleration directly associated with the flare itself and located in the lower corona and (2) acceleration by a supercritical shock driven by the associated coronal mass ejection, located at ∼3–5 solar radii and farther in the upper corona. A one‐to‐one association with so‐called impulsive and gradual solar energetic particle events at lower energies is proposed. On the basis of these observations, a generic model for the GLE is proposed.
Astronomical sky spectra from the 29–31 October 2003 geomagnetic superstorms: Observations of O+(2Do–4So) and other emissions
Authors: Sharpee B. D. , O'Neill E. R. , Slanger T. G.
Published: December 2008

High‐resolution spectra of the night sky at near‐equatorial latitudes have been obtained with the Ultraviolet and Visual Echelle Spectrograph on the 8.2 m Kueyen telescope, European Southern Observatory, Cerro Paranal, Chile, during the 29–31 October 2003 geomagnetic superstorms. These spectra show indications of both thermospheric and ionospheric disturbance. Numerous emission features observed in these spectra have behaviors that correlate with the negative magnitude of the disturbance storm time index (Dst), a measure of the ring current influence on equatorial magnetic field strength. Specifically, the intensity of the optically forbidden and rarely observed O+(2Do–4So) doublet lines at 372.6 and 372.9 nm increases with decreasing Dst and have profiles that often possess unusual morphology. Also observed on nights with strong geomagnetic activity is sustained emission after twilight from both the N2+ first negative system 0‐0 band at 391.4 nm and the He(3p3Po–2s3S) 388.9 nm line. The intensities of permitted neutral oxygen lines nominally arising from electron radiative recombination are suppressed during active periods relative to levels measured during quiescent periods. The pattern of emission in these spectra may reflect the manifestation of a variety of storm time phenomena, including negative ionospheric storms, energetic neutral auroras, and stable auroral red arcs, and indicates substantial energy deposition at high altitudes.
Enabling Global Collaboration in the Geosciences: Geoinformatics 2008; Potsdam, Germany, 11–13 June 2008
Authors: Klump Jens , Allison Lee , Asch Kristine , Fox Peter , Gundersen Linda , Jackson Ian , Loewe Peter , Snyder Walter S. , Ritschel Bernd
Published: December 2008

Scientists are facing an increasing flood of data and information in the Earth sciences from which they try to distill knowledge. The emerging discipline of geoinformatics brings together the tools necessary to create and make accessible the knowledge needed to respond to society's complex challenges, such as climate change, new energy and mineral resources, new sources of water, and protecting environmental and human health.

Globalization of geoinformatics‐based research and education in support of meeting societal challenges was the theme for the Geoinformatics 2008 conference, which was held at the German Research Centre for Geosciences, in Potsdam, Germany. Participants came from China, France, Germany, Japan, Netherlands, Russia, Switzerland, the United Kingdom, and the United States, representing academic institutions, national research centers, and government agencies.
Wrangellia flood basalts in Alaska: A record of plume‐lithosphere interaction in a Late Triassic accreted oceanic plateau
Authors: Greene Andrew R. , Scoates James S. , Weis Dominique
Published: December 2008

The Wrangellia flood basalts are part of one of the best exposed accreted oceanic plateaus on Earth. They provide important constraints on the construction of these vast submarine edifices and the source and temporal evolution of magmas for a plume head impinging beneath oceanic lithosphere. Wrangellia flood basalts (∼231–225 Ma) extend ∼450 km across southern Alaska (Wrangell Mountains and Alaska Range) where ∼3.5 km of mostly subaerial flows are bounded by late Paleozoic arc volcanics and Late Triassic limestone. The vast majority of the flood basalts are light rare earth element (LREE) ‐enriched high‐Ti basalt (1.6–2.4 wt % TiO2) with uniform ocean island basalt (OIB) ‐type Pacific mantle isotopic compositions (ɛHf(t) = +9.7 to +10.7; ɛNd(t) = +6.0 to +8.1; t = 230 Ma). However, the lowest ∼400 m of stratigraphy in the Alaska Range is LREE‐depleted low‐Ti basalt (0.4–1.2 wt % TiO2) with pronounced negative high field strength element (HFSE) anomalies and Hf isotopic compositions (ɛHf(t) = +13.7 to +18.4) that are decoupled from Nd (ɛNd(t) = +4.6 to +5.4) and displaced well above the OIB mantle array (ΔɛHf = +4 to +8). The radiogenic Hf of the low‐Ti basalts indicates involvement of a component that evolved with high Lu/Hf over time but not with a correspondingly high Sm/Nd. The radiogenic Hf and HFSE‐depleted signature of the low‐Ti basalts suggest pre‐existing arc lithosphere was involved in the formation of flood basalts that erupted early in construction of part of the Wrangellia plateau in Alaska. Thermal and mechanical erosion of the base of the lithosphere by the impinging plume head may have led to melting of arc lithosphere or interaction of plume‐derived melts and subduction‐modified mantle. The high‐Ti lavas dominate the main phase of construction of the plateau and were derived from a depleted mantle source distinct from the source of MORB and with compositional similarities to that of ocean islands (e.g., Hawaii) and plateaus (e.g., Ontong Java) in the Pacific Ocean.
Estuarine distributions of Zr, Hf, and Ag in the Hudson River and the implications for their continental and anthropogenic sources to seawater
Authors: Godfrey L. V. , Field M. P. , Sherrell R. M.
Published: December 2008

Zirconium and Hf in seawater are derived from continental weathering and are transported to the oceans by rivers, but the modification of this flux with estuaries is largely unknown. Furthermore, there is no information as to whether there is a pollutant source of these metals that might affect their budget calculations in the modern ocean. To address the riverine flux and potential anthropogenic sources, the distributions of dissolved Zr and Hf have been measured in surface and bottom water through the Hudson River Estuary. The distribution of Ag is included because it is sensitive to urban sources and has partial similarities in its distribution to those of Zr and Hf. There is about 50% removal of Zr and Hf in surface water relative to their freshwater end‐member concentrations of 243 and 3.1 pmol/kg as salinity starts to increase, but an urban source of these metals midestuary may obscure greater removal. Silver concentrations in surface water are below the detection limit until salinity of 3.5 is reached. The concentrations of Zr and Hf 0.5 m above the bottom are 1.5 to 3 times higher than their surface water concentrations throughout the estuary and may result from input of groundwater, diffusion from pore fluids, or inclusion of colloidal phases in our analyses. Downstream of the turbidity maximum, bottom water Ag concentrations are high due to release from particles that originally formed within the estuary and were moved inland following the spring freshet; this process may also affect Zr and Hf. The increase in the freshwater atomic Zr/Hf ratio from 70 to 80, characteristic of terrestrial rocks, to the elevated Zr/Hf (>110) ratio of seawater takes place at middle to high salinity due to enhanced release of Zr from resuspended particles and slower removal rates compared to Hf. A main implication of this study is that estuaries are a sink for Zr and Hf. The reduction of the predicted export of continental Zr and Hf to the oceans increases their previously calculated seawater residence by as much as 2 to 4 times, assuming rivers dominate the supply of Zr and Hf to seawater.
Globally aligned photomosaic of the Lucky Strike hydrothermal vent field (Mid‐Atlantic Ridge, 37°18.5′N): Release of georeferenced data, mosaic construction, and viewing software
Authors: Escartín J. , García R. , Delaunoy O. , Ferrer J. , Gracias N. , Elibol A. , Cufi X. , Neumann L. , Fornari D. J. , Humphris S. E. , Renard J.
Published: December 2008

We present a georeferenced photomosaic of the Lucky Strike hydrothermal vent field (Mid‐Atlantic Ridge, 37°18′N). The photomosaic was generated from digital photographs acquired using the ARGO II seafloor imaging system during the 1996 LUSTRE cruise, which surveyed a ∼1 km2 zone and provided a coverage of ∼20% of the seafloor. The photomosaic has a pixel resolution of 15 mm and encloses the areas with known active hydrothermal venting. The final mosaic is generated after an optimization that includes the automatic detection of the same benthic features across different images (feature‐matching), followed by a global alignment of images based on the vehicle navigation. We also provide software to construct mosaics from large sets of images for which georeferencing information exists (location, attitude, and altitude per image), to visualize them, and to extract data. Georeferencing information can be provided by the raw navigation data (collected during the survey) or result from the optimization obtained from image matching. Mosaics based solely on navigation can be readily generated by any user but the optimization and global alignment of the mosaic requires a case‐by‐case approach for which no universally software is available. The Lucky Strike photomosaics (optimized and navigated‐only) are publicly available through the Marine Geoscience Data System (MGDS, http://www.marine‐geo.org). The mosaic‐generating and viewing software is available through the Computer Vision and Robotics Group Web page at the University of Girona (http://eia.udg.es/∼rafa/mosaicviewer.html).
Precipitation of radiation belt electrons by EMIC waves, observed from ground and space
Authors: Miyoshi Y. , Sakaguchi K. , Shiokawa K. , Evans D. , Albert J. , Connors M. , Jordanova V.
Published: December 2008

We show evidence that left‐hand polarised electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere. Our unique set of ground and satellite observations shows coincident precipitation of ions with energies of tens of keV and of relativistic electrons into an isolated proton aurora. The coincident precipitation was produced by wave‐particle interactions with EMIC waves near the plasmapause. The estimation of pitch angle diffusion coefficients supports that the observed EMIC waves caused coincident precipitation of both ions and relativistic electrons. This study clarifies that ions with energies of tens of keV affect the evolution of relativistic electrons in the radiation belts via cyclotron resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970′s.
Ion composition in the plasma trough and plasma plume derived from a Combined Release and Radiation Effects Satellite magnetoseismic study
Authors: Takahashi Kazue , Ohtani Shin‐ichi , Denton Richard E. , Hughes W. Jeffrey , Anderson Roger R.
Published: December 2008

The mass and energy carried in the magnetosphere by heavy ions, O+ in particular, are known to increase as geomagnetic activity increases. However, the ion composition in the magnetosphere has not been fully specified since measurements of the flux of different ion species from the ionospheric thermal energy (below 1 eV) to the ring current energy (above 100 keV) are difficult with single‐particle instruments. We used mass density determined by a magnetoseismology technique and the electron density derived from measured plasma wave spectra to investigate the ion composition and total mass density for Combined Release and Radiation Effects Satellite (CRRES) orbit 962 (27−28 August 1991). This orbit occurred during a geomagnetic storm and included afternoon passes through the plasmasphere, the plasma trough, and a plasma plume, where these plasma regions were identified using the electron density ne. In the magnetoseismology analysis, we determined the fundamental frequency of the toroidal standing Alfvén waves fT1 from the electric and magnetic field data and then inferred the corresponding total mass density ρtotal at the satellite by solving an MHD wave equation with a realistic magnetic field model and a realistic assumption for the mass distribution along the field line. The value of fT1 changed little when the spacecraft moved between the plasma trough and the plasma plume, implying the dominance of heavy ions in the plasma trough. From the values of ne and ρtotal, we derived quantities associated with O+ by assuming that the plasma consisted of three ions, H+, He+, and O+. In the plasma trough, O+ ions are found to carry a number density of ∼10 cm−3, ∼50% of the number density, and ∼90% of the mass density. On the other hand, O+ is found to be much less dominant in the plasma plume. Our results are consistent with DE‐1 studies of the formation of an oxygen torus at the outer edge of the H+ plasmapause during geomagnetic active periods and with GEOS‐1 and GEOS‐2 studies that reported strong dependence of O+ density on geomagnetic activity and on solar extreme ultraviolet flux. In addition, our events indicate that the plasma plume boundary, defined in terms of the number density of electrons or light ions (H+ and He+), may not exhibit similar structure in the total mass density that can be readily detected using magnetoseismology techniques.
Assessment of the topography impact on microwave radiometry at L‐band
Authors: Monerris A. , Benedicto P. , Vall‐llossera M. , Camps A. , Santanach E. , Piles M. , Prehn R.
Published: December 2008

The TuRTLE 2006 field experiment aimed at evaluating, from a ground‐based point of view, the topography impact on microwave radiometry at L‐band. Observations of a mountainous area 50 km north of Barcelona, Spain, were acquired using the fully polarimetric radiometer LAURA (1.4135 GHz working frequency). The look angle was changed in elevation and azimuth to observe a wide area which included almost bare surfaces, shrubs growing at the valley descending slope, and mixed woodland present at the ascending slope of the mountain in front of LAURA (at the other side of the valley). Ground‐truth soil moisture and temperature, vegetation water content, and meteorological parameters were also sampled. Radiometric measurements have been compared to antenna temperatures simulated using a facet model which takes into account the high‐resolution digital elevation model and the land cover map of the experiment site, the polarization mixing due to surface tilting, and the radiometer's antenna radiation pattern. Four different scenarios have been simulated: (1) a hypothetical scenario without vegetation and without topography, (2) a hypothetical scenario without topography but with the actual land cover map of the experiment site, (3) a hypothetical scenario without vegetation but with the digital elevation map of the experiment site, and (4) the actual experiment site, including both the digital elevation model and the land cover map. Simulations using a facet model agreed with measurements only when both topography and the land cover map were considered. The largest discrepancies occur for almost bare soils at large local incidence angles, which suggests that further modeling work is still needed for this case.
Stratigraphic variation of transport properties and overpressure development in the Western Foothills, Taiwan
Authors: Tanikawa Wataru , Shimamoto Toshihiko , Wey Sheng‐Kuen , Lin Ching‐Weei , Lai Wen‐Chi
Published: December 2008

Overpressure, fluid pressure higher than hydrostatic pressure, has developed below the middle Miocene formations in the north central Western Foothills of Taiwan. To study the mechanism by which overpressure is generated and maintained in the Taiwan oil fields, we estimated the fluid pressure history and overpressure distribution by using a one‐dimensional basin model incorporating laboratory‐approximated hydraulic parameters. Transport properties of outcropping sedimentary rocks were measured at effective pressures of 5 to 200 MPa. All parameters showed apparent stratigraphic variation, decreasing with increasing burial depth. Permeability showed the strongest sensitivity to depth, decreasing by 6 orders of magnitude to 10−20 m2 at the bottom of the basin. A critical sealing layer was not identified in the geologic column. The basin model incorporates overburden loading due to sediment accumulation, aquathermal expansion of water, the dehydration reaction of expandable clay to nonexpandable clay, and oil generation. Predicted overpressure was generated dramatically from 3 Ma, when the accumulation rate increased rapidly as a result of tectonic collisions in the area. If we assume a fluid influx from the bottom of the basin, the predicted overpressure is consistent with the observed overpressure, implying that continuous inflow from depth, possibly along the décollement or normal faults, may be the main cause of overpressure generation in this area. Stratigraphic variation of transport properties, which decrease with depth, also influences overpressure trends in the Western Foothills, where overpressure is generated only in deeper horizons. The clay mineral distribution estimated by a kinetic smectite‐illite dehydration model is consistent with the observed mineralogical data.
Carbon deposition during brittle rock deformation: Changes in electrical properties of fault zones and potential geoelectric phenomena during earthquakes
Authors: Mathez E. A. , Roberts J. J. , Duba A. G. , Kronenberg A. K. , Karner S. L.
Published: December 2008

To investigate potential mechanisms for geoelectric phenomena accompanying earthquakes, we have deformed hollow cylinders of Sioux quartzite to failure in the presence of carbonaceous pore fluids and investigated the resulting changes in electrical conductivity and carbon distribution. Samples were loaded at room temperature or 400°C by a hydrostatic pressure at their outer diameter, increasing pressure at a constant rate to ∼290 MPa. Pore fluids consisted of pure CO, CO2, and CH4 and a 1:1 mixture of CO2 and CH4, each with pore pressures of 2.0 to 4.1 MPa. Failure occurred by the formation of Mode II shear fractures transecting the hollow cylinder walls. Radial resistivities of the cylinders fell to 2.9 to 3.1 MΩ‐m for CO tests and 15.2 to 16.5 MΩ‐m for CO2:CH4 tests, compared with >23 MΩ‐m for dry undeformed cylinders. Carbonaceous fluids had no discernable influence on rock strength. On the basis of mapping using electron microprobe techniques, carbon occurs preferentially as quasi‐continuous films on newly formed fracture surfaces, but these films are absent from preexisting surfaces in those same experiments. The observations support the hypothesis that electrical conductivity of rocks is enhanced by the deposition of carbon on fracture surfaces and imply that electrical properties may change in direct response to brittle deformation. They also suggest that the carbon films formed nearly instantaneously as the cracks formed. Carbon film deposition may accompany the development of microfracture arrays prior to and during fault rupture and thus may be capable of explaining precursory and coseismic geoelectric phenomena.
Ice nucleation properties of the most abundant mineral dust phases
Authors: Zimmermann Frank , Weinbruch Stephan , Schütz Lothar , Hofmann Heiko , Ebert Martin , Kandler Konrad , Worringen Annette
Published: December 2008

The ice nucleation properties of the nine most abundant minerals occurring in desert aerosols (quartz, albite, microcline, kaolinite, montmorillonite, illite, calcite, gypsum, and hematite) were investigated by environmental scanning electron microscopy (ESEM). In this instrument, the pure minerals are exposed to water vapor at variable pressures and temperatures. The crystallization of ice on the mineral particles is observed by secondary electron imaging, and the supersaturation for an activated particle fraction of 1–3% is determined as function of temperature. In all experiments, condensation of water prior to ice formation was not observed within detectable limits, even at water supersaturation. The highest temperatures for 1–3% activation vary between −10°C and −16°C for the nine minerals investigated, and the corresponding onset relative humidities relative to ice RHi between 107 and 117%. Supersaturation temperature curves for initial ice formation (1–3% activation) in the temperature range typical for mixed‐phase clouds were measured for all nine minerals. The temperature dependence of the onset relative humidity is strongly dependent on mineralogy. Kaolinite, montmorillonite, and hematite show a strong increase in RHi with decreasing temperature, whereas RHi is almost constant for illite, albite, quartz, and calcite. The highly variable ice nucleation properties of the various mineral dust components should be considered for parameterization schemes. Illite and kaolinite are the most important minerals to consider, as they have high ice nucleation efficiency and are common components of desert aerosols.
Determination of the effective thermal conductivity of granular materials under varying pressure conditions
Authors: Huetter E. S. , Koemle N. I. , Kargl G. , Kaufmann E.
Published: December 2008

We report on thermal conductivity measurements performed on glass spheres of different grain sizes under varying pressure conditions ranging from 10−5 up to 1000 hPa. Glass spheres of 0.1 up to 4.3 mm were used as an analogue for the coarse‐grained fractions of planetary regolith. From the obtained conductivity versus pressure data, sample pore sizes were derived and compared to estimated pore sizes. An increasing difference between derived and estimated pore size with increasing grain size was found. The behavior of the granular matter with decreasing pressure was analyzed by estimating the Knudsen number for the given system. The results indicate a high variability of the effective thermal conductivity for Martian conditions. Furthermore, the results imply that the thermal conductivity reaches a grain size‐dependent, but pressure‐independent, value for pressures below 0.01 hPa. For vacuum conditions a linear relation between grain size and effective thermal conductivity was found. Additionally, a mixture was analyzed, which showed a stronger decrease with gas pressure compared to the single‐sized samples. From the pore size derived for the mixture an “effective” grain size composed of weighted mean of the mixture components was determined.
Colorful microdiversity of Synechococcus strains (picocyanobacteria) isolated from the Baltic Sea
Authors: Haverkamp Thomas H A , Schouten Daphne , Doeleman Marije , Wollenzien Ute , Huisman Jef , Stal Lucas J
Published: December 2008

Synechococcus is a cosmopolitan genus of picocyanobacteria living in the photic zone of freshwater and marine ecosystems. Here, we describe the isolation of 46 closely related picocyanobacterial strains from the Baltic Sea. The isolates showed considerable variation in their cell size and pigmentation phenotypes, yielding a colorful variety of red, pink and blue-green strains. These pigmentation phenotypes could not be differentiated on the basis of their 16S rRNA-internal transcribed spacer (ITS) sequences. Thirty-nine strains, designated BSea, possessed 16S rRNA-ITS sequences almost identical with Synechococcus strain WH5701. Despite their similar 16S rRNA-ITS sequences, the BSea strains separated into several different clusters when comparing the phycocyanin (cpcBA) operon. This separation was largely consistent with the phycobiliprotein composition of the different BSea strains. The majority of phycocyanin (PC)-rich Bsea strains clustered with WH5701. Remarkably, the phycoerythrin (PE)-rich strains of BSea formed an as yet unidentified cluster within the cpcBA phylogeny, distantly related to other PE-rich groups. Detailed analysis of the cpcBA operon using neighbour-net analysis indicated that the PE-rich BSea strains are probably endemic for the Baltic Sea. Comparison of the phylogenies obtained by the 16S rRNA-ITS, the cpcBA, and the concatenated 16S rRNA-ITS and cpcBA operon sequences revealed possible events of horizontal gene transfer among different Synechococcus lineages. Our results show that microdiversity is important in Synechococcus populations and that it can reflect extensive diversification of different pigmentation phenotypes into different ecological niches.
The Effects of Rimonabant on Brown Adipose Tissue in Rat: Implications for Energy Expenditure
Authors: Verty Aaron N.A. , Allen Andrew M. , Oldfield Brian J.
Published: December 2008

The cannabinoid CB1 receptor antagonist rimonabant (SR 141716) produces a sustained decrease in body weight on a background of a transient reduction in food intake. An increase in energy expenditure has been implicated, possibly mediated via peripheral endocannabinoid system; however, the role of the central endocannabinoid system is unclear. The present study investigates this role. Rimonabant (10 mg/kg IP) was administered for 21 days to rats surgically implanted with biotelemetry devices to measure temperature in the interscapular brown adipose tissue (BAT). BAT temperature as a putative measure of thermogenesis in the BAT, physical activity, body weight, food intake, as well as changes in UCP1 messenger RNA (mRNA) and protein were measured. In addition, role of the CNS in mediating these actions of rimonabant was determined in rats where the BAT was sympathetically denervated. As expected, chronic administration of rimonabant significantly reduced body weight for the entire treatment period despite only a transient decrease in food intake. There was a profound increase in BAT temperature, particularly during the dark phase of each circadian cycle throughout the treatment period. A corresponding increase in uncoupling protein (UCP1) was also observed following chronic rimonabant treatment. The rimonabant‐induced elevation in BAT temperature and decrease in body weight were significantly attenuated following denervation, indicating an involvement of the CNS. These findings suggest that the long‐term weight loss associated with rimonabant treatment is due at least in part to an elevation in energy expenditure, represented here by elevated temperature recorded in the BAT, which is mediated primarily by the central endocannabinoid system.
The Effect of Dietary Glycemic Index on Weight Maintenance in Overweight Subjects: A Pilot Study
Authors: Philippou Elena , Neary Nicola M. , Chaudhri Owais , Brynes Audrey E. , Dornhorst Anne , Leeds Anthony R. , Hickson Mary , Frost Gary S.
Published: December 2008

Evidence suggests that a low‐glycemic index (LGI) diet has a satiating effect and thus may enhance weight maintenance following weight loss. This study was conducted at Hammersmith Hospital, London, UK, and assessed the effect of altering diet GI on weight‐loss maintenance. It consisted of a weight‐loss phase and a 4‐month randomized weight maintenance phase. Subjects were seen monthly to assess dietary compliance and anthropometrics. Appetite was assessed bimonthly by visual analogue scales while meal challenge postprandial insulin and glucose concentrations were assessed before and after the intervention. Following a median weight loss of 6.1 (interquartile range: 5.2–7.1) % body weight, subjects were randomized to a high‐glycemic index (HGI) (n = 19) or LGI (n = 23) diet. Dietary composition differed only in GI (HGI group: 63.7 ± 9.4; LGI group: 49.7 ± 5.7, P < 0.001) and glycemic load (HGI group: 136.8 ± 56.3; LGI group: 89.7 ± 27.5, P < 0.001). Groups did not differ in body weight (weight change over 4 months, HGI group: 0.3 ± 1.9 kg; LGI group: −0.7 ± 2.9 kg, P = 0.3) or other anthropometric measurements. This pilot study suggests that in the setting of healthy eating, changing the diet GI does not appear to significantly affect weight maintenance.
Relationship of Serum γ‐Glutamyltransferase to Atherogenic Dyslipidemia and Glycemic Control in Type 2 Diabetes
Authors: Zoppini Giacomo , Targher Giovanni , Trombetta Maddalena , Lippi Giuseppe , Muggeo Michele
Published: December 2008

We evaluated possible interactions between BMI and serum γ‐glutamyltransferase (GGT) concentration and their effects on the prevalence of poor glycemic control and common comorbidities of diabetes. We assessed whether the association of BMI with poor glycemic control, hypertension, atherogenic dyslipidemia (i.e., high triglycerides and/or low high‐density lipoprotein (HDL) cholesterol), hypercholesterolemia, and hyperuricemia differed according to serum GGT concentration in a cohort of 3,633 type 2 diabetic individuals. The associations of BMI with different outcome measures were significant, but the associations varied remarkably by GGT concentration. As GGT concentration increased, the association of BMI with atherogenic dyslipidemia and glycemic control strengthened (P = 0.01 and 0.004 for interactions, respectively); in contrast, the association of BMI with hypertension, hypercholesterolemia, and hyperuricemia did not change substantially across GGT quartiles. For example, within the lowest GGT quartile, BMI was not associated with atherogenic dyslipidemia or poor glycemic control, whereas in the highest GGT quartile, the prevalence rates ranged from 62.3 to 74.7% for dyslipidemia and from 75.3 to 83% for poor glycemic control. The results remained unchanged after adjustment for sex, age, alcohol consumption, diabetes duration, and diabetes treatment. In conclusion, our findings show that BMI was associated with atherogenic dyslipidemia and poor glycemic control only when serum GGT activity was in its high‐normal range. These findings suggest that obesity itself may not be a sufficient risk factor for atherogenic dyslipidemia or poor glycemic control in people with type 2 diabetes.
Adiponectin Improves Cardiomyocyte Contractile Function in db/db Diabetic Obese Mice
Authors: Dong Feng , Ren Jun
Published: December 2008

Low levels of adiponectin, a fat‐derived hormone, are found to be correlated with coronary heart disease, type 2 diabetes, obesity, and insulin resistance. Conversely, high adiponectin levels are predictive of reduced coronary risk in long‐term epidemiologic studies. However, the precise role of adiponectin in cardiomyocyte function is still not clear. This study was designed to examine the role of adiponectin in cardiac contractile function in the db/db model of diabetic obesity. Mechanical properties and intracellular Ca2+ transients were evaluated in cardiomyocytes from lean control and db/db mice with or without adiponectin (10 µg/ml) treatment. Expression and phosphorylation of IRS‐1, Akt, c‐Jun, and c‐Jun N terminal kinase (JNK) as well as markers of endoplasmic reticulum (ER) stress were evaluated using western blotting. Cardiomyocytes from db/db mice exhibited greater cross‐sectional area, depressed peak shortening (PS), and maximal velocity of shortening/re‐lengthening as well as prolonged duration of re‐lengthening. Consistently, myocytes from db/db mice displayed a reduced electrically stimulated rise in intracellular Ca2+ and prolonged intracellular Ca2+ decay, which were abrogated by adiponectin treatment. Ratios between phosphorylated c‐Jun and c‐Jun as well as phosphorylated IRS‐1 and IRS‐1 were increased in db/db mice, the effect of which was attenuated by adiponectin. Levels of the phosphorylated ER stress makers PERK (Thr980), IRE‐1, and eIF2α were significantly elevated in db/db mice compared with lean controls, although the effect was unaffected by adiponectin. Collectively, our data suggest that adiponectin improves cardiomyocyte dysfunction in db/db diabetic obese mice through a mechanism possibly related to c‐Jun and IRS‐1.
Patterns of Growth Associated With the Timing of Adiposity Rebound
Authors: Williams Sheila M. , Goulding Ailsa
Published: December 2008

This study was undertaken to evaluate the effects of age of adiposity rebound (AR) on measures of fat mass between ages 7 and 11 years, maturity, and adiposity in 458 children from a birth cohort studied to age 26 years. Patterns of growth between ages 3 and 26 years and changes in fat mass index between 7 and 11 years in groups with early (<5.5 years for boys and <5 years for girls), average (between 5.5 and 7.5 years for boys and between 5 and 7 years for girls), and late AR (≥7.5 years for boys and ≥7 years for girls) are described. The mean z‐scores for BMI, height, and weight increased between age 3 years and adolescence in the early‐rebound group and decreased in the late‐rebound group. The differences were maintained until adulthood for BMI and weight. Disproportionately high increases in fat mass index during growth (7–11 years), more advanced bone age in boys at age 7 years, and earlier menarche in girls were evident in the early‐rebound group. The relative risks at 26 years of being overweight (BMI 25–29.9 kg/m2) and obese (BMI ≥30 kg/m2) were 2.70 (95% confidence interval (CI): 1.55, 4.66) and 5.91 (95% CI: 3.03, 11.55) respectively, using the average group as the reference. The corresponding relative risks for adult waist girths exceeding international cut points were 2.12 (95% CI: 1.09, 4.13) and 3.32 (95% CI: 1.46, 7.54). Thus, early rebound is associated with increased depositions of fat in middle childhood, and risks associated with early rebound persist at least until early adulthood.
Severely Obese Have Greater LPS‐stimulated TNF‐α Production Than Normal Weight African‐American Women
Authors: Kueht Michael L. , McFarlin Brian K. , Lee Rebecca E.
Published: December 2008

Obesity is associated with an increase in chronic, low‐grade inflammation which has been implicated in the development of type 2 diabetes mellitus and cardiovascular disease. The purpose of this study was to determine whether obesity was associated with an elevation of whole blood lipopolysaccharide (LPS)‐stimulated tumor necrosis factor‐α (TNF‐α) production. African‐American women were recruited from a larger study and assigned to one of five groups based on BMI: normal weight (NORM; BMI 20–25, n = 7), overweight (OVER; BMI 25–30, n = 12), class 1 obese (OB1; BMI 30–35, n = 19), class 2 obese (OB2; BMI 35–40, n = 10), or class 3 obese (OB3; BMI >40, n = 17). Body composition was determined via a whole body dual‐energy X‐ray absorptiometry (DXA) scan. Venous blood samples were collected following an overnight fast (>8 h), and stimulated with five doses of LPS (Salmonella enteriditis): 80, 40, 20, 10, and 5 µg/ml for 24 h in a 37 °C, 5% CO2 incubator. Following stimulation, TNF‐α was measured using enzyme‐linked immunosorbent assay. OB3 produced 365% more TNF‐α than NORM at an LPS dose of 20 µg/ml (P < 0.05). When maximal TNF‐α production was assessed regardless of LPS dose, OB3 produced 230% more than NORM and OVER produced 190% more than NW (P = 0.001). Total and trunk fat mass and BMI were significantly correlated with maximal TNF‐α production and LPS = 20 µg/ml. Our findings are consistent with previous reports suggesting a relationship between increased adiposity and inflammatory marker production. This is one of the first studies to focus on African‐American women, who have higher rates of obesity.