bluuebunny/crossref_metadata_2025 huggingface dataset:
Procalcitonin und seine Bedeutung für die Diagnose bakterieller Infektionen
Authors: Christ-Crain Mirjam , Schuetz Philipp , Huber Andreas R. , Müller Beat
Published: September 2008

Procalcitonin ist das Pro-Hormon von Calcitonin. Im Gegensatz zu Calcitonin, welches primär in der Schilddrüse gebildet wird, wird Procalcitonin bei einer bakteriellen Infektion im ganzen Körper von allen parenchymatösen Organen produziert. Insbesondere bei der Diagnosestellung von milderen, lokalisierten oder beginnenden Infektionen muss ein sensitiver Assay verwendet werden mit einer funktionellen Assay Sensitivität, die idealerweise in den Bereich von gesunden Individuen messen kann (etwa 0.02 μg/L). Procalcitonin konnte aufgrund seiner überlegenen diagnostischen Eigenschaften bei Atemwegsinfektionen die initiale Antibiotikaverschreibung, sowie die Dauer der Antibiotikatherapie sowohl im Spital als auch im ambulanten Bereich in der Hausarztpraxis stark (um 40–75%) reduzieren. Prognostisch ist Procalcitonin bei Eintritt zwar anderen Infektionsmarkern überlegen, mit jedoch eingeschränkter Aussagekraft. Insbesondere der Verlauf von Procalcitonin kann aber über die Prognose Auskunft geben: sehr hohe und im Verlauf ansteigende Werte zeigen ein hohes Risiko für ungünstigen Verlauf an. Trotz diesen Vorteilen gegenüber anderen Infektionsmarkern ist Procalcitonin kein perfekter Marker für Infektionen. So kann er falsch hoch sein bei nicht-bakteriellen Erkrankungen wie zum Beispiel posttraumatisch, bei Malaria, bei schwersten Entzündungen oder einem medullären Schilddrüsenkarzinom, und bleibt bei streng lokalisierten Infektionen in einem relativ tiefen Bereich. Wie jeder andere Biomarker sollte Procalcitonin deshalb immer im Kontext von gekonnter Anamnese und klinischer Untersuchung interpretiert werden. Dann jedoch kann mittels Procalcitonin die Diagnose eines bakteriellen Infektes deutlich verbessert werden.
Increased organic C and N leaching in a northern boreal river basin in Finland
Authors: Lepistö Ahti , Kortelainen Pirkko , Mattsson Tuija
Published: September 2008

Increasing trends in dissolved organic carbon concentrations in small lakes and streams have been reported across Europe and North America. Several hypotheses have been proposed, of which decreasing mineral acidity has recently been considered to be the most likely cause. The near‐natural, northern Simojoki river basin (3160 km2) is located in the northern boreal zone in Finnish Lapland. Human impacts are minor with only limited forest management, low atmospheric deposition, and declining sulfate and H+ deposition over recent decades. Here we show that multiple effects (changes both in hydrological dynamics and in climate) explain increasing long‐term total organic carbon (TOC) and total organic nitrogen (TON) fluxes in the river. Strong fluctuation was observed in the TOC concentration time series during the studied 43 year time period from 1962 to 2005. Statistically significant upward trends were detected for TON concentration and flow of the river during 1976–2005. The average TOC and TON flux increased by 38% and 42%, respectively, during the 1990s compared with the 1980s. The annual runoff was 27% higher during the 1990s than during the 1980s, accounting for only part of the increase in the TOC and TON outputs. Hydrological fluctuations, including longer drought/wet periods, are important. For example the drought period of 1994–1997 with low concentrations was followed by high TOC and TON concentration peaks and strong leaching fluxes during the period 1998–2000. Average soil temperatures in winter (January–April) in the 1990s were 1.6–2.1°C higher than in the 1980s. This increase may have contributed to increasing trends in organic N concentrations particularly during winter low flow, because of increased organic matter decomposition rates during the dormant season. These changes in decomposition rates might further intensify in warmer climatic conditions.
Diurnal variation in plasmaspheric He+ inferred from extreme ultraviolet images
Authors: Galvan David A. , Moldwin Mark B. , Sandel Bill R.
Published: September 2008

A diurnal variation in He+ density is observed using successive snapshots of the plasmasphere taken by the extreme ultraviolet (EUV) imager on the IMAGE spacecraft. Analysis of average EUV photon counts from a specific patch of plasma, which may move at a rate other than corotation, centered at L = 2.5 and L = 3.5 over successive images during an IMAGE pass, allows us to follow a flux tube and track the brightness variation across ∼6–10 h of local time. These EUV brightness observations are converted to He+ column‐integrated densities by taking into account solar EUV flux as measured by the SOHO spacecraft. Variations in He+ column density with local time provide insight into the process of plasmaspheric refilling by ionospheric plasma outflow on diurnal time scales. An analysis of 128 orbits of IMAGE EUV data in 2001 reveals that EUV photon count, and hence column‐integrated He+ density, tends to increase soon after dawn, decrease or stagnate around noon, and strongly increase in late afternoon through dusk. These observations show no significant dependence on geomagnetic activity and support the idea that diurnal refilling of the plasmasphere is largely controlled by increased photoionization at dawn by exposure of the ionosphere to sunlight. Azimuthal profiles of individual EUV images provide additional evidence for the same trend observed in the tracking technique and show that He+ column abundance values are typically 50–100% higher at dusk than dawn.
Examination of scaling between earthquake magnitude and proposed early signals inPwaveforms from very near source stations in a South African gold mine
Authors: Lewis M. A. , Ben‐Zion Y.
Published: September 2008

We analyze near‐source seismograms recorded in a deep South African mine for scaling between signals early inPwaveforms and the magnitudeMof the events. The data consist of recordings at 26 stations of 122 events with −1.5 <M< 2.5 and hypocentral distances as low as ∼60 m. We examine four signals belonging to two classes. Signals in the first class include Ellsworth‐Beroza and Iio measurements, assumed to reflect signatures of seismic nucleation phases. Signals in the second class consist of Nakamura‐type predominant period and Wu‐Zhao corrected peak displacement in the early waveforms, related to measures of the stress drop and local magnitude. Candidates for the Ellsworth‐Beroza signals, involving a weak arrival before the mainPphase, exist for only 20–30% of the waveforms. These phases do not appear to be associated with a general component of the rupture initiation process. The Iio signal increases with increasingMbut may be attributed, at least partially, to statistical effects. The predominant period and peak displacement have significant correlations withM, which remain robust when the analysis time window is reduced from 3 s or before theSwave arrival to 0.01 s. The latter is shorter than the estimated rupture duration for events withM> ∼0, implying that the final earthquake size is affected statistically by the initial rupture process. If these correlations hold for larger earthquakes, as suggested by other studies, the early predominant period and peak displacement are useful for early warning systems.
Temporal and spatial variability of vertical salt flux in a highly stratified estuary
Authors: MacDonald Daniel G. , Horner‐Devine Alexander R.
Published: September 2008

The temporal and spatial variability of vertical salt flux in the Fraser River Estuary, British Columbia, was investigated observationally, using several different direct and indirect indicators of buoyancy flux. Data were collected from the estuary using shipboard instrumentation, primarily an acoustic Doppler current profiler and a towed conductivity‐temperature‐depth unit. Direct estimates of buoyancy flux were made from along‐channel control volume analyses and from measurements of overturn scales. The spatial and temporal evolution of the salt wedge structure through a tidal cycle was evaluated using the results of these buoyancy flux calculations, as well as gradient Richardson number, Froude number, and stratification profiles. Observations indicate that buoyancy flux is driven primarily by interfacial stress, and not bottom stress, as is common in many estuaries. Vertical salt flux, as opposed to seaward advection of high‐salinity fluid, was found to be the dominant mechanism responsible for removal of salt from the estuarine channel during each daily tidal cycle. Buoyancy flux was highly variable in time and space, however, with vertical salt flux during ebb tides on the order of 2 to 3 times greater than that estimated during floods. This is due to an increase in the vertical shear of horizontal velocity and a sharp increase in stratification, which was observed during early ebb. Enhanced mixing was observed spatially within a region dominated by a channel constriction in which the channel narrows by approximately 25%.
Observation of enhanced ozone in an electrically active storm over Socorro, NM: Implications for ozone production from corona discharges
Authors: Minschwaner K. , Kalnajs L. E. , Dubey M. K. , Avallone L. M. , Sawaengphokai P. C. , Edens H. E. , Winn W. P.
Published: September 2008

Enhancements in ozone were observed between about 3 and 10 km altitude within an electrically active storm in central New Mexico. Measurements from satellite sensors and ground‐based radar show cloud top pressures between 300 and 150 mb in the vicinity of an ozonesonde launched from Socorro, NM, and heavy precipitation with radar reflectivities exceeding 50 dBZ. Data from a lightning mapping array and a surface electric field mill show a large amount of electrical activity within this thunderstorm. The observed ozone enhancements are large (50% above the mean) and could have resulted from a number of possible processes, including the advection of polluted air from the urban environments of El Paso and Juarez, photochemical production by lightning‐generated NOx from aged thunderstorm outflow, downward mixing of stratospheric air, or local production from within the thunderstorm. We find that a large fraction of the ozone enhancement is consistent with local production from corona discharges, either from cloud particles or by corona associated with lightning. The implied global source of ozone from thunderstorm corona discharge is estimated to be 110 Tg O3 a−1 with a range between 40 and 180 Tg O3 a−1. This value is about 21% as large as the estimated ozone production rate from lightning NOx, and about 3% as large as the total chemical production rate of tropospheric ozone. Thus while the estimated corona‐induced production of ozone may be significant on local scales, it is unlikely to be as important to the global ozone budget as other sources.
Constraints on the elastic thickness, heat flow, and melt production at early Tharsis from topography and magnetic field observations
Authors: Jellinek A. M. , Johnson C. L. , Schubert G.
Published: September 2008

The southern half of the Tharsis region of Mars displays enigmatic variations in the crustal magnetic field that are correlated with topography and the distribution of volcanism. Radial magnetic field anomaly values (Br) at 400 km altitude are greater than 25 nT over areas at elevations less than about 6 km, Br = 0 over areas at higher elevations where volcanism is also concentrated. Assuming that much of the uplift and magmatism of Tharsis postdates the crustal magnetic field, we hypothesize that the absence of radial field in the central part of the rise is related to enhanced heat flow from an underlying mantle plume. A parameterized mantle convection model, combined with a heat transfer requirement for crustal demagnetization and analysis of the dynamic topography provides restrictive and self‐consistent constraints on the plume structure, excess temperature ΔTex and heat flux qp as well as the average elastic thickness de at Tharsis at the time of uplift. These results lead, in turn, to bounds on the long‐term average magma supply from the mantle. ΔTex is found to be in the range 205–240°C and upper bounds for de are 29–40 km, depending on the magnitude of the dynamic topography. Assuming magnetite is the dominant magnetic carrier, these results imply also that the lower 50–60% of the crustal column is raised above the Curie temperature and thermally demagnetized. The plume heat flux qp ≈ 60–100 mW m2 and corresponds to melt production rate Q ≈ 0.01–0.03 km3 a−1, comparable to minimum estimates determined from geological data for the rate of Noachian‐Hesperian volcanism.
On the saltation of fresh snow in a wind tunnel: Profile characterization and single particle statistics
Authors: Guala M. , Manes C. , Clifton A. , Lehning M.
Published: September 2008

We present experimental results on the snow drift in a turbulent boundary layer over a flat fresh snow‐covered surface. Vertical profiles of mass flux and of the distribution of particle diameters were obtained by means of a pair of Snow Particle Counters parallel with measurements of the stream‐wise velocity profile. The aim of the paper is to discuss current parameterizations of the vertical mass flux profile for fresh snow and to investigate the range of timescales involved in a developing saltation layer occurring in a turbulent boundary layer. The novelty of the work consists of using an intact fresh snow cover as an erodible surface able to provide realistic snow crystals as drifting particles. Results show that (1) the parameters scaling the vertical mass flux profiles of fresh snow can significantly differ from those given in the literature for ice or compacted snow particles; (2) though drifting snow covers an extremely wide range of temporal scales, the mean time interval between saltating particles 〈Δt〉 is the key timescale of the saltation process; (3) 〈Δt〉 allows for the optimal reconstruction of the mass flux as a continuous signal and for neglecting the effects related to the heterogeneous distribution of particle size on the mass flux. Implications on the modeling of snow drift and on the processing of field observations are discussed.
A study of precursors to equatorial spread F using the Giant Meterwave Radio Telescope
Authors: DasGupta A. , Paul A. , Ray S. , Das A. , Ananthakrishnan S.
Published: September 2008

This paper reports the results of an experiment to identify a possible precursor to equatorial spread F (ESF) with the Giant Meterwave Radio Telescope (GMRT) (latitude: 19.10°N, longitude: 74.05°E geographic; dip: 23°N magnetic) near Pune by simultaneously recording the amplitude and phase of the signal from the radio source 3C218 (RA:09h15m, Declination:−11°) at 235, 327, 610, and 1420 MHz in the postsunset‐premidnight period 18.5–22.5 LT on 26, 29, and 31 March 2004. Patches of scintillations both in amplitude and phase were observed on 26 and 29 March 2004 at 235, 327, and 610 MHz frequencies starting around 20 LT (LT = UT + 05:00) and extending until 22 LT while the records for 31 March 2004 do not show any scintillations. Significant amplitude scintillations were not observed at 1420 MHz. The most remarkable feature was the presence of large‐scale periodic structures in phase prior to onset of amplitude scintillations. The Total Electron Content (TEC) as observed on a GPS link also looking through the same ionospheric volume showed periodic variation of carrier phase prior to onset of scintillations and bite‐outs in TEC, which implies that before the onset of ESF, the large‐scale wave structures propagate to the height of maximum ionization and beyond.
Buffered, lagged, or cooled? Disentangling hyporheic influences on temperature cycles in stream channels
Authors: Arrigoni Alicia S. , Poole Geoffrey C. , Mertes Leal A. K. , O'Daniel Scott J. , Woessner William W. , Thomas Steven A.
Published: September 2008

We monitored summertime base flow water temperatures of hyporheic discharge to surface water in main, side, and spring channels located within the bank‐full scour zone of the gravel‐ and cobble‐bedded Umatilla River, Oregon, USA. Diel temperature cycles in hyporheic discharge were common, but spatially variable. Relative to the main channel's diel cycle, hyporheic discharge locations typically had similar daily mean temperatures, but smaller diel ranges (compressed by 2 to 6°C) and desynchronized phases (offset by 0 to 6 h). In spring channels (which received only hyporheic discharge), surface water diel cycles were also compressed (by 2 to 6°C) and desynchronized (by −4 to 6 h) relative to the main channel, creating diverse daytime and nighttime mosaics of surface water temperatures across main, side, and spring channels, despite only minor differences (<1°C) in daily mean temperatures among the channels. The river's hyporheic zone received and stored heat from the channel, yet hyporheic return flows carried heat back to the channel minutes to months after removal. Associated surface water temperature dynamics were therefore complex. Hyporheic discharge was not simply “cooler” or “warmer” than main channel water. Instead, instantaneous temperature differences between channel water and hyporheic discharge typically arose from diel temperature cycles in hyporheic discharge that were buffered and lagged relative to diel cycles in the main channel.
Interfacial area based variable tortuosity‐connectivity for unsaturated media: A comparison using Miller–Miller scaling and Arya–Paris model
Authors: Khaleel Raziuddin
Published: September 2008

The tortuosity and/or pore connectivity factor, τ, in unsaturated media is typically represented by Seɛ, where Se = effective saturation. The exponent ɛ is treated as an optimized parameter with typical values of 0.5 and 2, respectively, for Mualem and Burdine‐type models. In this study, the tortuosity and/or connectivity term in Mualem and Burdine models is replaced by a normalized ratio, τ(Se = 1) / τ(Se); τ(Se) is the ratio of air–water interfacial area for a soil sample to the interfacial area for the corresponding idealized capillary bundle. The interfacial area for a soil sample is based on Leverett's (1941) thermodynamic considerations and is obtained by integrating the area under the laboratory‐measured moisture retention curve. In addition to Miller–Miller scaling used in an earlier work, the idealized medium retention curve in this study is based on translation via the Arya–Paris (AP) model of the particle size distribution data for a soil sample into its pore size distribution. The saturation‐dependent, variable tortuosity concept is tested for 24 fine‐textured samples in addition to 22 coarse‐textured samples considered in the earlier study. For both fine‐ and coarse‐textured samples, the interfacial area based variable τ(Se) formulation provides at least as good a fit of the measured and predicted unsaturated hydraulic conductivities, K, as a function of moisture content, θ, as the standard Brooks–Corey–Burdine and van Genuchten–Mualem models. Specifically, for the fine‐textured samples, Brooks–Corey–Burdine K(θ) predictions based on the variable τ(Se) model compare well with K(θ) measurements, with an r2 of 0.86, a regression slope of 1.02, and a relatively low residual mean squared deviation of 1.13. Unlike the Burdine (Se2) and Mualem (Se0.5) empirical models, the τ(Se)‐based model parameters have explicit physical significance because the interfacial area in unsaturated media can be measured using interfacial tracers. The use of the AP model to represent the idealized medium retention data suggests its broader applicability for both fine‐ and coarse‐textured media.
Pressure‐induced magnetic transition and sound velocities of Fe3C: Implications for carbon in the Earth's inner core
Authors: Gao Lili , Chen Bin , Wang Jingyun , Alp Esen E. , Zhao Jiyong , Lerche Michael , Sturhahn Wolfgang , Scott Henry P. , Huang Fang , Ding Yang , Sinogeikin Stanislav V. , Lundstrom Craig C. , Bass Jay D. , Li Jie
Published: September 2008

We have carried out nuclear resonant scattering measurements on 57Fe‐enriched Fe3C between 1 bar and 50 GPa at 300 K. Synchrotron Mössbauer spectra reveal a pressure‐induced magnetic transition in Fe3C between 4.3 and 6.5 GPa. On the basis of our nuclear resonant inelastic X‐ray scattering spectra and existing equation‐of‐state data, we have derived the compressional wave velocity VP and shear wave velocity VS for the high‐pressure nonmagnetic phase, which can be expressed as functions of density (ρ): VP(km/s) = −3.99 + 1.29ρ(g/cm3) and VS(km/s) = 1.45 + 0.24ρ(g/cm3). The addition of carbon to iron‐nickel alloy brings density, VP and VS closer to seismic observations, supporting carbon as a principal light element in the Earth's inner core.
Combined surface solar brightening and increasing greenhouse effect support recent intensification of the global land‐based hydrological cycle
Authors: Wild Martin , Grieser Jürgen , Schär Christoph
Published: September 2008

The surface net radiation (surface radiation balance) is the key driver behind the global hydrological cycle. Here we present a first‐order trend estimate for the 15‐year period 1986–2000, which suggests that surface net radiation over land has rapidly increased by about 2 Wm−2 per decade, after several decades with no evidence for an increase. This recent increase is caused by increases in both downward solar radiation (due to a more transparent atmosphere) and downward thermal radiation (due to enhanced concentrations of atmospheric greenhouse‐gases). The positive trend in surface net radiation is consistent with the observed increase in land precipitation (3.5 mmy−1 per decade between 1986 and 2000) and the associated intensification of the land‐based hydrological cycle. The concurrent changes in surface net radiation and hydrological cycle were particularly pronounced in the recovery phase following the Mount Pinatubo volcanic eruption, but remain evident even when discarding the Pinatubo‐affected years.
Wave structures of the plasma density and vertical E × B drift in low‐latitude F region
Authors: Kil H. , Talaat E. R. , Oh S.‐J. , Paxton L. J. , England S. L. , Su S.‐Y.
Published: September 2008

We investigate the seasonal, longitudinal, local time (LT), and altitudinal variations of the F region morphology at low latitudes using data from the first Republic of China satellite (ROCSAT‐1), Global Ultraviolet Imager (GUVI), on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, and the Defense Meteorological Satellite Program (DMSP) F13 and F15 satellites. Signatures of the longitudinally periodic plasma density structure emerge before 0900 LT. The wave structure is established before noon and further amplified in the afternoon. The amplitudes of the wave structure start to diminish in the evening. The wave‐4 structure is clearly distinguishable during equinox and northern hemisphere summer. During northern hemisphere winter, the density structure can be characterized to either wave‐4 or wave‐3 structure owing to marginal separation of the two peaks in 180°–300°E. Observations of similar density structures from ROCSAT‐1 (600 km) and DMSP (840 km) at 0930 and 1800 LT indicate the extension of the wave structure to altitudes greater than 840 km. The daytime wave structure persists into the night during the equinoxes but is significantly modified during the solstices. The modification is more significant at higher altitudes and is attributed to the effects of interhemispheric winds and the prereversal enhancement. The formation of the wavelike density structure in the morning and its temporal evolution in the afternoon show a close association with the vertical E × B drift. We conclude that the E × B drift during 0900–1200 LT determines the formation of the wavelike density structure.
Magnetic signatures and conjugate features of low‐latitude plasma blobs as observed by the CHAMP satellite
Authors: Park Jaeheung , Stolle Claudia , Lühr Hermann , Rother Martin , Su Shin‐Yi , Min Kyoung Wook , Lee Jae‐Jin
Published: September 2008

We investigated the magnetic signatures of plasma blobs, as observed by the CHAMP satellite. In total, we have identified 52 blobs with clear density enhancements and magnetic signatures. In each blob the magnetic field strength was depressed, and the components perpendicular to the main magnetic field direction showed fluctuations. The variation in magnetic field strength implies that the enhanced plasma pressure is balanced by a magnetic pressure reduction, and the deflection in the perpendicular components indicates the presence of field‐aligned currents. Both characteristics are consistent with bubble magnetic signatures. Concurrent observations of CHAMP (at ∼350 km altitude) with ROCSAT‐1 (∼600 km), STSAT‐1 (∼680 km), and DMSP F15 (∼840 km) strongly suggest that the blobs have a field‐aligned structure spanning several hundred kilometers. We also investigated the seasonal/longitudinal distribution of the detected blob events. From that a rough coincidence with the bubble occurrence distribution is found, although the blob distribution is biased heavily toward the winter hemisphere. Plasma blob encounters at CHAMP altitude are quite frequent, even after local midnight. We believe that our results corroborate the close relationship between equatorial plasma bubbles and blobs.
Response of the expanding/contracting polar cap to weak and strong solar wind driving: Implications for substorm onset
Authors: Milan S. E. , Boakes P. D. , Hubert B.
Published: September 2008

We quantify the amount of open magnetic flux in the magnetosphere from observations of the auroral polar cap on a near‐continuous basis for a period of 18 days, 20 August to 6 September 2005. This interval encompasses periods of weak, moderate, and strong solar wind driving, including two geomagnetic storms. We identify 49 substorms during the interval and determine the response of the polar cap to growth and expansion phases of the substorms. We find that the frequency of substorms and the flux closed by substorms both increase during enhanced solar wind driving, each approximately as the square root of the dayside reconnection rate. In addition, the average size of the polar cap increases during intervals when there is strong driving and especially when the SYM‐H index indicates that the ring current is enhanced. We suggest that this occurs for two reasons: because there is a delay between substorm onset and the closure of open magnetic flux in the magnetotail (while closed flux is pinched off), during which dayside reconnection can lead to further growth in the size of the polar cap, and also because the magnetotail is more stable to reconnection when the ring current is enhanced.
Refraction of a Gaussian seaway
Authors: Heller E. J. , Kaplan L. , Dahlen A.
Published: September 2008

Refraction of a Longuet‐Higgins Gaussian sea by random ocean currents creates persistent local variations (in the form of lumps or streaks) in average energy and wave action distributions. These variations explicitly survive averaging over wavelength and wave propagation direction. The lumps and streaks in average local action mean that the uniform sampling assumed in the venerable Longuet‐Higgins theory does not apply. Proper handling of the nonuniform sampling results in greatly increased probability of freak wave formation. The present theory represents a synthesis of Longuet‐Higgins Gaussian seas and the refraction model of White and Fornberg, which used a non‐Gaussian nonstatistical plane wave incident seaway. Using the linearized equations for deep ocean waves, we obtain quantitative predictions for the increased probability of freak wave formation when the refractive effects are taken into account. The wave height distribution depends primarily on the “freak index,” γ, which measures the strength of refraction relative to the angular spread of the incoming sea. Dramatic effects are obtained in the tail of this distribution even for the modest values of the freak index that are expected to occur commonly in nature. Extensive comparisons are made between the analytical description and numerical simulations.
Radon and radium isotope assessment of submarine groundwater discharge in the Yellow River delta, China
Authors: Peterson Richard N. , Burnett William C. , Taniguchi Makoto , Chen Jianyao , Santos Isaac R. , Ishitobi Tomotoshi
Published: September 2008

Naturally occurring chemical tracers were used to assess the magnitude of submarine groundwater discharge (SGD) during two different sampling periods at a coastal site south of the Yellow River delta, China. We used salinity and pH as indicators of the terrestrial and recirculated seawater components of discharging groundwater and radium isotopes to quantify offshore transport rates. We then used an hourly time series of multiple radium isotopes (224Ra, 223Ra, and 226Ra) to quantify SGD rates and also used 222Rn and seepage meters to independently quantify SGD rates as a comparison to the radium results. Offshore transport rates were found to range from 3.3 to 4.7 cm s−1. Modeled time series radium activities indicated average SGD rates ranging from 4.5 to 13.9 cm d−1 in September 2006 and from 5.2 to 11.8 cm d−1 in July 2007. Temporal trends associated with the radium approach agree with SGD patterns revealed by automated seepage meters deployed nearby, but the absolute fluxes are about 70% lower than those determined by the seepage meters. Modeled SGD rates based on 222Rn (mean = 13.8 cm d−1 in 2006 and 8.4 cm d−1 in 2007) agree with those determined by the radium analysis. Differences in derived SGD rates between the different radium isotopes (226Ra highest; 224Ra lowest) are likely results of uncertainties in the background activities and our limited selection of appropriate groundwater/pore water end‐member values. Scaling our results to the entire Yellow River delta, we find SGD fluxes (and corresponding nitrate fluxes) 2–3 times that of the Yellow River.
Geomorphologic and mineralogic characterization of the northern plains of Mars at the Phoenix Mission candidate landing sites
Authors: Seelos K. D. , Arvidson R. E. , Cull S. C. , Hash C. D. , Heet T. L. , Guinness E. A. , McGuire P. C. , Morris R. V. , Murchie S. L. , Parker T. J. , Roush T. L. , Seelos F. P. , Wolff M. J.
Published: September 2008

A suite of remote sensing data is used to evaluate both geomorphology and mineralogy of the candidate landing sites for the 2007 Phoenix Mission. Three candidate landing site boxes are situated in the northern plains of Mars on the distal flank of Alba Patera in the region from 67°N to 72°N and from ∼230°E to 260°E. Geomorphology is mapped at subkilometer spatial scales using Thermal Emission Imaging System (THEMIS) visible and Mars Orbiter Laser Altimeter (MOLA) topographic data, supplemented by images from the High‐Resolution Imaging Science Experiment (HiRISE) and Context Imager (CTX). Mineralogy and spectral properties are examined using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) visible and near‐infrared multispectral mapping and targeted hyperspectral data at ∼200 and ∼20 m/pixel, respectively. Geomorphic mapping supports the idea that terrains along the boundary between the Amazonian Scandia region and Vastitas Borealis marginal geologic units have undergone extensive modification. Intercrater plains are disrupted to form mesas and interlocking blocks, while irregular depressions and knobby terrain are consistent with erosion/subsidence and local deposition. Despite the varied morphology, the present‐day surface is nearly homogeneous with spectral signatures dominated by nanophase iron oxides and basaltic sand and rocks, similar to that of the Gusev crater plains at the Mars Exploration Rover (MER) landing site. The compilation of geomorphic and spectral information for the candidate Phoenix landing sites provides a framework for the mission's in situ observations to be extrapolated to the northern plains as a whole.
Man‐made space weather
Authors: Mendillo Michael , Smith Steven , Coster Anthea , Erickson Philip , Baumgardner Jeffrey , Martinis Carlos
Published: September 2008

Major geomagnetic storms produce dramatic gradients in the ionosphere's total electron content (TEC) that cause errors in GPS‐dependent navigation systems, such as those used by the U. S. Coast Guard and the Federal Aviation Administration. Here we describe the first use of GPS signals to detect large‐scale gradients in TEC very similar to those found during ionospheric storms but produced instead by the exhaust gases of a large Titan rocket launched from the Kennedy Space Center. The severe ionospheric perturbations of 30 April 2005, observed simultaneously by optical emission from the thermosphere and by GPS diagnostics of the ionosphere, describe a unique type of space weather effect caused by nonnatural sources.
Protective Effect of Post-Ischaemic Viral Delivery of Heat Shock Proteins in vivo
Authors: Badin Romina A , Modo Michael , Cheetham Mike , Thomas David L , Gadian David G , Latchman David S , Lythgoe Mark F
Published: September 2008

Heat shock proteins (HSPs) function as molecular chaperones involved in protein folding, transport and degradation and, in addition, they can promote cell survival both in vitro and in vivo after a range of stresses. Although some in vivo studies have suggested that HSP27 and HSP70 can be neuroprotective, current evidence is limited, particularly when HSPs have been delivered after an insult. The effect of overexpressing HSPs after transient occlusion of the middle cerebral artery in rats was investigated by delivering an attenuated herpes simplex viral vector (HSV-1) engineered to express HSP27 or HSP70 30 mins after tissue reperfusion. Magnetic resonance imaging scans were used to determine lesion size and cerebral blood flow at six different time points up to 1 month after stroke. Animals underwent two sensorimotor tests at the same time points to assess the relationship between lesion size and function. Results indicate that post-ischaemic viral delivery of HSP27, but not of HSP70, caused a statistically significant reduction in lesion size and induced a significant behavioural improvement compared with controls. This is the first evidence of effective post-ischaemic gene therapy with a viral vector expressing HSP27 in an experimental model of stroke.
KLF5 enhances SREBP-1 action in androgen-dependent induction of fatty acid synthase in prostate cancer cells
Authors: Lee Min-Young , Moon Jong-Seok , Park Sahng Wook , Koh Yoo-kyung , Ahn Yong-Ho , Kim Kyung-Sup
Published: September 2008

KLF5 (Krüppel-like factor 5) is a zinc-finger transcription factor that plays a critical role in the regulation of cellular signalling involved in cell proliferation, differentiation and oncogenesis. In the present study, we showed that KLF5 acts as a key regulator controlling the expression of FASN (fatty acid synthase) through an interaction with SREBP-1 (sterol-regulatory-element-binding protein-1) in the androgen-dependent LNCaP prostate cancer cell line. The mRNA level of KLF5 increased when cells were treated with a synthetic androgen, R1881. Furthermore, KLF5 bound to SREBP-1 and enhanced the SREBP-1-mediated increase in FASN promoter activity. The results also demonstrated that the expression of KLF5 in LNCaP prostate cancer cells enhanced FASN expression, whereas silencing of KLF5 by small interfering RNA down-regulated FASN expression. The proximal promoter region and the first intron of the FASN gene contain multiple CACCC elements that mediate the transcriptional regulation of the gene by KLF5. However, other lipogenic and cholesterogenic genes, such as those encoding acetyl-CoA carboxylase, ATP-citrate lyase, the LDL (low-density lipoprotein) receptor, HMG-CoA (3-hydroxy-3-methylglutaryl-CoA) synthase and HMG-CoA reductase are irresponsive to KLF5 expression, owing to the absence of CACCC elements in their promoter regions. Taken together, these results suggest that the FASN gene is activated by the synergistic action of KLF5 and SREBP-1, which was induced by androgen in androgen-dependent prostate cancer cells.
Hepatitis B virus X protein induces lipogenic transcription factor SREBP1 and fatty acid synthase through the activation of nuclear receptor LXRα
Authors: Kim KyeongJin , Kim Kook Hwan , Kim Hyeong Hoe , Cheong JaeHun
Published: September 2008

HBV (hepatitis B virus) is a primary cause of chronic liver disease, which frequently results in hepatitis, cirrhosis and ultimately HCC (hepatocellular carcinoma). Recently, we showed that HBx (HBV protein X) expression induces lipid accumulation in hepatic cells mediated by the induction of SREBP1 (sterol-regulatory-element-binding protein 1), a key regulator of lipogenic genes in the liver. However, the molecular mechanisms by which HBx increases SREBP1 expression and transactivation remain to be clearly elucidated. In the present study, we demonstrated that HBx interacts with LXRα (liver X receptor α) and enhances the binding of LXRα to LXRE (LXR-response element), thereby resulting in the up-regulation of SREBP1 and FAS (fatty acid synthase) in the presence or absence of the LXR agonist T0901317 in the hepatic cells and HBx-transgenic mice. Furthermore, HBx also augments the ability to recruit ASC2 (activating signal co-integrator 2), a transcriptional co-activator that controls liver lipid metabolic pathways, to the LXRE with LXRα. These studies place LXRα in a key position within the HBx-induced lipogenic pathways, and suggest a molecular mechanism through which HBV infection can stimulate the SREBP1-mediated control of hepatic lipid accumulation.
A novel short splice variant of the tumour suppressor LKB1 is required for spermiogenesis
Authors: Towler Mhairi C. , Fogarty Sarah , Hawley Simon A. , Pan David A. , Martin David M. A. , Morrice Nicolas A. , McCarthy Afshan , Galardo María N. , Meroni Silvina B. , Cigorraga Selva B. , Ashworth Alan , Sakamoto Kei , Hardie D. Grahame
Published: September 2008

LKB1 was discovered as a tumour suppressor mutated in Peutz-Jeghers syndrome, and is a gene involved in cell polarity as well as an upstream protein kinase for members of the AMP-activated protein kinase family. We report that mammals express two splice variants caused by alternate usage of 3′-exons. LKB1L is the previously described form, while LKB1S is a novel form in which the last 63 residues are replaced by a unique 39-residue sequence lacking known phosphorylation (Ser431) and farnesylation (Cys433) sites. Both isoforms are widely expressed in rodent and human tissues, although LKB1S is particularly abundant in haploid spermatids in the testis. Male mice in which expression of Lkb1S is knocked out are sterile, with the number of mature spermatozoa in the epididymis being dramatically reduced, and those spermatozoa that are produced have heads with an abnormal morphology and are non-motile. These results identify a previously undetected variant of LKB1, and suggest that it has a crucial role in spermiogenesis and male fertility.
The discrete Feynman integral
Authors: Dorlas T. C. , Thomas E. G. F.
Published: September 2008

We construct a genuine Radon measure with values in B(ℓ2(Zd)) on the set of paths in Zd representing Feynman’s integral for the discrete Laplacian on ℓ2(Zd), and we prove the Feynman integral formula for the solutions of the Schrödinger equation with Hamiltonian H=−12Δ+V, where Δ is the discrete Laplacian and V is an arbitrary bounded potential.
The conductivity of Bi(111) investigated with nanoscale four point probes
Authors: Wells J. W. , Handrup K. , Kallehauge J. F. , Gammelgaard L. , Bøggild P. , Balslev M. B. , Hansen J. E. , Petersen P. R. E. , Hofmann Ph.
Published: September 2008

The room temperature conductance of Bi(111) was measured using microscopic four point probes with a contact spacing down to 500 nm. The conductance is remarkably similar to that of the bulk, indicating that surface scattering is not a major mechanism for restricting the mobility at this length scale. Also, the high density of electronic surface states on Bi(111) does not appear to have a major influence on the measured conductance. The lower limit for the resistivity due to electronic surface states is found to be around 5 Ω. With such a value for the surface resistivity, surface conduction should not be a significant factor to inhibit the observation of the predicted semiconductor to semimetal transition for thin films of Bi.
Giant dielectric response in two-dimensional charge-ordered nickelate ceramics
Authors: Liu Xiao Qiang , Wu Shu Ya , Chen Xiang Ming , Zhu Hai Yan
Published: September 2008

Dielectric relaxations of charge-ordered Ln1.5Sr0.5NiO4 (Ln=La and Nd) ceramics were investigated over a broad temperature range. The giant dielectric constant (over 70 000) with a low dielectric loss of ∼0.1 was determined at high frequencies (up to 5 MHz) over a broad temperature range. There are two dielectric relaxations in the vicinity of charge ordering temperatures. The thermal activated small polaronic hopping between two charge ordering temperatures should contribute to the giant dielectric response in the present ceramics. Compared to other giant dielectric constant materials, the present materials have the notable advantage for high frequency applications.
Charge migration following ionization in systems with chromophore-donor and amine-acceptor sites
Authors: Lünnemann Siegfried , Kuleff Alexander I. , Cederbaum Lorenz S.
Published: September 2008

The ultrafast charge migration following outer-valence ionization in three different but related molecules, namely, 2-phenylethyl-N,N-dimethylamine (PENNA), and its butadiene (MePeNNA) and ethylene (BUNNA) derivates, is studied in detail. The molecules have different chromophore-donor sites, but nearly identical amine-acceptor sites. The results show that the charge migration process depends strongly on the particular donor site, varying from ultrafast migration of the charge from the donor to the acceptor site (4fs for MePeNNA) to no migration at all (for BUNNA). The influence of the geometrical structure of the molecule on the charge migration is also investigated. It is shown that energetically closely lying conformers may exhibit dramatically different charge migration behaviors. The basic mechanism of the charge migration process in the studied molecules is analyzed in detail and is demonstrated to be due to electron correlation and relaxation effects.
Bond strength and interface energy between Pd membranes and TiAl supports
Authors: Gong H. R. , He Y. H. , Huang B. Y.
Published: September 2008

Intermetallic TiAl alloy is proposed as a promising support for Pd membranes. First principles calculations reveal that coherent Pd/TiAl interfaces possess high values of bond strengths. Calculations also show that Ti-terminated (100) Pd/(100) TiAl and (110) Pd/(110) TiAl interfaces are energetically favorable with negative interface energies of about −3.1 J/m2, and that the bond strengths of Pd–Ti are bigger than those of Pd–Al. In addition, densities of states calculations suggest that a stronger chemical bonding is formed in the Pd/TiAl interface than corresponding Pd or TiAl bulks, which agrees well with similar experimental observations in literature.
Irreversible magnetic exchange-spring processes in antiferromagnetic exchange-coupled bilayer systems
Authors: Guo Guang-hua , Zhang Guang-fu , Song San-yuan , Wang D. W. , Bowden G. J. , de Groot P. A. J.
Published: September 2008

The demagnetization processes of antiferromagnetic exchange-coupled hard-soft bilayer structures have been studied using a one-dimensional atomic chain model, taking into account the anisotropies of both hard and soft layers. It is found that for very thin soft layers, magnetization/demagnetization involves typical reversible exchange-spring behavior. However as the thickness t of the soft layer is increased, there is a crossover point tc, after which the exchange spring becomes irreversible. The value of the critical thickness tc is determined inter alia by the magnetic anisotropy of the soft layer. However, an important feature of the irreversible exchange spring is the formation of a large angle domain wall, realized immediately at the bending field transition.
Adsorption-controlled growth of EuO by molecular-beam epitaxy
Authors: Ulbricht R. W. , Schmehl A. , Heeg T. , Schubert J. , Schlom D. G.
Published: September 2008

Using molecular-beam epitaxy, we demonstrate the adsorption-controlled growth of epitaxial EuO films on single crystalline (110) YAlO3 substrates. Four-circle x-ray diffraction (XRD) reveals phase-pure, epitaxial, (001)-oriented films with rocking curve full width at half maxima as narrow as 34 arc sec (0.0097°). The critical thickness for the onset of relaxation of (001) EuO on (110) YAlO3 (∼2% lattice mismatch) was determined from XRD measurements to be 382±25 Å. A saturation magnetization of 6.96±0.07μB/Eu, a value close to the theoretical limit of 7μB/Eu, is observed.
Giant improvement of thermoelectric power factor of Bi2Te3 under pressure
Authors: Ovsyannikov Sergey V. , Shchennikov Vladimir V. , Vorontsov Grigoriy V. , Manakov Andrey Y. , Likhacheva Anna Y. , Kulbachinskii Vladimir A.
Published: September 2008

The pressure (P) dependencies of both the thermopower (Seebeck effect) S and the electrical resistance (R) for p-type single crystals of Bi2Te3 and indium-doped bismuth telluride (InxBi2−xTe3,0.04≤x≤0.10) are reported on a pressure range of 0–8.5 GPa. The thermoelectric power factor (efficiency) (æ=S2/R) exhibits two maxima: the first one near ∼1 GPa and the second near ∼2.5–4.5 GPa. These features evidence a giant increase in the power factor by a factor of ∼10. Possible values of the dimensionless figure of merit under pressure are also estimated. The maxima are explained in terms of pressure-driven changes in an electron structure. The second feature may be also addressed to an intermediate high-pressure phase detected in x-ray diffraction studies.
Improvement in both giant magnetoresistance and exchange bias through hydrogen ion irradiation at low energy
Authors: Shim Jaechul , Han Yoonsung , Lee Jinwon , Hong Jongill
Published: September 2008

Irradiation of IrMn-based spin valves with 550 eV hydrogen ions increased their giant magnetoresistance and exchange bias by 20% and 60%, respectively. This significant enhancement stems from the strong (111) texture and small mosaic spread of the IrMn antiferromagnet that resulted from the microstructural reconstruction caused by the energy transfer during the bombardment by hydrogen ions, as well as by the narrow dispersion in the exchange bias. Irradiation with the hydrogen ion at low energy can improve the properties of spin valves without resulting in undue degradation in the performance or the microstructure.
Benchmarks for electronically excited states: Time-dependent density functional theory and density functional theory based multireference configuration interaction
Authors: Silva-Junior Mario R. , Schreiber Marko , Sauer Stephan P. A. , Thiel Walter
Published: September 2008

Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole moments are computed using the same geometries (MP2/6-31G∗) and basis set (TZVP) as in our previous ab initio benchmark study on electronically excited states. The results from TD-DFT (with the functionals BP86, B3LYP, and BHLYP) and from DFT/MRCI are compared against the previous high-level ab initio results, and, in particular, against the proposed best estimates for 104 singlet and 63 triplet vertical excitation energies. The statistical evaluation for the latter reference data gives the lowest mean absolute deviations for DFT/MRCI (0.22 eV for singlets and 0.24 eV for triplets) followed by TD-DFT/B3LYP (0.27 and 0.44 eV, respectively), whereas TD-DFT/BP86 and TD-DFT/BHLYP are significantly less accurate. The energies of singlet states with double excitation character are generally overestimated by TD-DFT, whereas triplet state energies are systematically underestimated by the currently investigated DFT-based methods.