Evidence for anthropogenic ¹⁴C-enrichment in estuarine waters adjacent to the North Sea

[1] The isotopic composition (d13C and D14C) of high molecular weight dissolved organic carbon (HMW DOC) was studied in the Tyne and Tweed estuaries, NE England. Despite significant removal of terrigenous HMW DOC in the low salinity regions (S < 15), D14C remained modern with little variation around 115%. This lack of apparent age discrimination was attributed to either non-oxidative removal or the absence of a significant proportion of old refractory C in the HMW DOC pool. At S < 15, we observed seaward increases in d13C and D14C. With no documented local 14C inputs, we attributed non-bomb related 14C-enrichment at S < 15 to a possible ‘lingering effect’ of distal anthropogenic sources in near-coastal North Sea HMW DOC. Given the global distribution of potential sources, we propose that anthropogenic 14C should be considered in assigning ages of DOC pools in near-coastal waters and suggest its possible use as a tracer for DOC transformations

Effects of Fish Populations on Pacific Loon (Gavia pacifica) and Yellow-billed Loon (G. adamsii) Lake Occupancy and Chick Production in Northern Alaska

  Predator populations are vulnerable to changes in prey distribution or availability. With warming temperatures, lake ecosystems in the Arctic are predicted to change in terms of hydrologic flow, water levels, and connectivity with other lakes. We surveyed lakes in northern Alaska to understand how shifts in the distribution or availability of fish may affect the occupancy and breeding success of Pacific (Gavia pacifica) and Yellow-billed Loons (G. adamsii). We then modeled the influence of the presence and abundance of five fish species and the physical characteristics of lakes (e.g., hydrologic connectivity) on loon lake occupancy and chick production. The presence of Alaska blackfish (Dallia pectoralis) had a positive influence on Pacific Loon occupancy and chick production, which suggests that small-bodied fish species provide important prey for loon chicks. No characteristics of fish species abundance affected Yellow-billed Loon lake occupancy. Instead, Yellow-billed Loon occupancy was influenced by the physical characteristics of lakes that contribute to persistent fish populations, such as the size of the lake and the proportion of the lake that remained unfrozen over winter. Neither of these variables, however, influenced chick production. The probability of an unoccupied territory becoming occupied in a subsequent year by Yellow-billed Loons was low, and no loon chicks were successfully raised in territories that were previously unoccupied. In contrast, unoccupied territories had a much higher probability of becoming occupied by Pacific Loons, which suggests that Yellow-billed Loons have strict habitat requirements and suitable breeding lakes may be limited. Territories that were occupied had high probabilities of remaining occupied for both loon species.  Les populations de prédateurs sont vulnérables aux changements de répartition ou de disponibilité des proies. En raison du réchauffement des températures, on prévoit que les écosystèmes lacustres de l’Arctique changeront pour ce qui est du régime hydrologique, des niveaux d’eau et de la connectivité avec d’autres lacs. Nous avons examiné des lacs du nord de l’Alaska pour comprendre comment les changements en matière de répartition ou de disponibilité des poissons peuvent avoir des incidences sur le taux d’occupation et sur le succès de reproduction du huart du Pacifique (Gavia pacifica) et du huart à bec blanc (G. adamsii). Ensuite, nous avons modélisé l’influence de la présence et de l’abondance de cinq espèces de poissons de même que les caractéristiques physiques de lacs (comme la connectivité hydrologique) par rapport au taux d’occupation lacustre des huarts et à la production d’oisillons. La présence du dallia (Dallia pectoralis) avait une influence positive sur l’occupation et la production d’oisillons chez le huart du Pacifique, ce qui suggère que les espèces de poissons au petit corps constituent une proie importante pour les oisillons. Aucune caractéristique de l’abondance des espèces de poissons n’a eu d’influence sur l’occupation lacustre du huart à bec blanc. L’occupation du huart à bec blanc a plutôt été influencée par les caractéristiques physiques des lacs qui contribuent aux populations de poissons persistantes, comme la taille du lac et la proportion du lac qui ne gelait pas en hiver. Toutefois, aucune de ces variables n’a exercé d’influence sur la production d’oisillons. La probabilité qu’un territoire inoccupé devienne occupé par le huart au bec blanc au cours d’une année subséquente était faible, et aucun oisillon huart n’a été élevé avec succès dans des territoires d’oisillons anciennement inoccupés. En revanche, les territoires inoccupés avaient une beaucoup plus grande probabilité de devenir occupés par les huarts du Pacifique, ce qui suggère que les huarts à bec blanc ont des exigences strictes en matière d’habitat et que le nombre de lacs convenant à la reproduction risque d’être limité. Les territoires qui étaient occupés avaient de fortes probabilités de rester occupés par les deux espèces de huarts

Concept for a Time-of-Flight Small Angle Neutron Scattering Instrument at the European Spallation Source

A new Small Angle Neutron Scattering instrument is proposed for the European Spallation Source. The pulsed source requires a time-of-flight analysis of the gathered neutrons at the detector. The optimal instrument length is found to be rather large, which allows for a polarizer and a versatile collimation. The polarizer allows for studying magnetic samples and incoherent background subtraction. The wide collimation will host VSANS and SESANS options that increase the resolution of the instrument towards um and tens of um, respectively. Two 1m2 area detectors will cover a large solid angle simultaneously. The expected gains for this new instrument will lie in the range between 20 and 36, depending on the assessment criteria, when compared to up-to-date reactor based instruments. This will open new perspectives for fast kinetics, weakly scattering samples, and multi-dimensional contrast variation studies.Comment: 18 pages, 10 figure

Superconductivity in novel Ge-based skutterudites: {Sr,Ba}Pt_4Ge_{12}

Combining experiments and ab initio models we report on $\rm SrPt_4Ge_{12}$ and $\rm BaPt_4Ge_{12}$ as members of a novel class of superconducting skutterudites, where Sr or Ba atoms stabilize a framework entirely formed by Ge-atoms. Below $T_c=5.35$ K, and 5.10 K for $\rm BaPt_4Ge_{12}$ and $\rm SrPt_4Ge_{12}$, respectively, electron-phonon coupled superconductivity emerges, ascribed to intrinsic features of the Pt-Ge framework, where Ge-$p$ states dominate the electronic structure at the Fermi energy.Comment: 4 pages, 4 figures, accepted for publication in PR

The impact of phenotypic and genetic heterogeneity on results of genome wide association studies of complex diseases

Phenotypic misclassification (between cases) has been shown to reduce the power to detect association in genetic studies. However, it is conceivable that complex traits are heterogeneous with respect to individual genetic susceptibility and disease pathophysiology, and that the effect of heterogeneity has a larger magnitude than the effect of phenotyping errors. Although an intuitively clear concept, the effect of heterogeneity on genetic studies of common diseases has received little attention. Here we investigate the impact of phenotypic and genetic heterogeneity on the statistical power of genome wide association studies (GWAS). We first performed a study of simulated genotypic and phenotypic data. Next, we analyzed the Wellcome Trust Case-Control Consortium (WTCCC) data for diabetes mellitus (DM) type 1 (T1D) and type 2 (T2D), using varying proportions of each type of diabetes in order to examine the impact of heterogeneity on the strength and statistical significance of association previously found in the WTCCC data. In both simulated and real data, heterogeneity (presence of "non-cases") reduced the statistical power to detect genetic association and greatly decreased the estimates of risk attributed to genetic variation. This finding was also supported by the analysis of loci validated in subsequent large-scale meta-analyses. For example, heterogeneity of 50% increases the required sample size by approximately three times. These results suggest that accurate phenotype delineation may be more important for detecting true genetic associations than increase in sample size

Effects of partial substitution of Ni by Pd on the thermoelectric properties of ZrNiSn-based half-Heusler compounds

We report on the effects of partial substitution of nickel by palladium on the thermoelectric properties of ZrNiSn-based half-Heusler compounds. It is shown that the substitution of palladium for nickel results in a significant, beneficial reduction of the thermal conductivity. The Seebeck coefficient also decreases, but only by a small amount. In the Hf0.5Zr0.5Ni0.8Pd0.2Sn0.99Sb0.01Hf0.5Zr0.5Ni0.8Pd0.2Sn0.99Sb0.01 compound, a power factor of 22.1 μW K−2 cm−1 and a thermal conductivity as low as 4.5 W/m K are measured at room temperature. The dimensionless figure of merit ZT increases with increasing temperature and reaches a maximum value of 0.7 at about 800 K. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70206/2/APPLAB-79-25-4165-1.pd

Observation of Magnetic Flux Generated Spontaneously During a Rapid Quench of Superconducting Films

We report observations of spontaneous formation of magnetic flux lines during a rapid quench of YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ films through T$_{c}$. This effect is predicted according to the Kibble-Zurek mechanism of creation of topological defects of the order parameter during a symmetry-breaking phase transition. Our previous experiment, at a quench rate of 20K/sec, gave null results. In the present experiment, the quench rate was increased to \TEXTsymbol{>} 10$^{8}$ K/sec. Within experimental resolution, the dependence of the measured flux on the cooling rate is consistent with the prediction

Impulsive light-scattering by coherent phonons in LaAlO3: Disorder and boundary effects

Pump-probe measurements of coherent-phonon-induced changes of refractive index in LaAlO3 are dominated by normally weak boundary effects. Atomic displacements in the range 50–500 μÅ were generated and probed by femtosecond laser pulses through impulsive Raman scattering. The absence of a bulk contribution is ascribed to phase mismatch due to domain disorder. Selection rules are consistent with a Raman model considering reflection and transmission at interfaces. Intensities and phonon parameters as a function of temperature agree well with incoherent Raman data

ABCG2 Is a Selectable Marker for Enhanced Multilineage Differentiation Potential in Periodontal Ligament Stem Cells.

Periodontal ligament stem cells (PDLSCs) provide an important source for tissue regeneration and may become especially useful in the formation of osteogenic seeds. PDLSCs can be cultured, expanded, and differentiated in vitro; thus, they may be applied in the long-term treatment of the defects in the dental regions. Here we studied numerous potential markers allowing the selection of human PDLSCs with a maximum differentiation potential. We followed the expression of the ATP-binding cassette subfamily G member 2 (ABCG2) membrane transporter protein and isolated ABCG2-expressing cells by using a monoclonal antibody, recognizing the transporter at the cell surface in intact cells. The expression of the ABCG2 protein, corresponding to the so-called side-population phenotype in various tissue-derived stem cells, was found to be a useful marker for the selection of PDLSCs with enhanced osteogenic, chondrogenic, and adipogenic differentiation. These findings may have important applications in achieving efficient dental tissue regeneration by using stem cells from extracted teeth