Climate fluctuations and the spring invasion of the North Sea by Calanus finmarchicus

The population of Calanus finmarchicus in the North Sea is replenished each spring by invasion from an overwintering stock located beyond the shelf edge. A combincation of field observations, statistical analysis of Continuous Plankton Recorder (CPR) data, and particle tracking model simulations, was used to investigate the processes involved in the cross-shelf invasion. The results showed that the main source of overwintering animals entering the North Sea in the spring is at depths of greater than 600m in the Faroe Shetland Channel, where concentrations of up to 620m -3 are found in association with the overflow of Norwegian Sea Deep Water (NSDW) across the Iceland Scotland Ridge. The input of this water mass to the Faroe Shetland Channel, and hence the supply of overwintering C. finmarchicus, has declined since the late 1960s due to changes in convective processes in the Greenland Sea. Beginning in February, animals start to emerge from the overwintering state and migrate to the surface waters, where their transport into the North Sea is mainly determined by the incidence of north-westerly winds that have declined since the 1960s. Together, these two factors explain a high proportion of the 30-year trends in spring abundance in the North Sea as measured by the CPR survey. Both the regional winds and the NSDW overflow are connected to the North Atlantic Oscillation Index (NAO), which is an atmospheric climate index, but with different time scales of response. Thus, interannual fluctuations in the NAO can cause immediate changes in the incidence of north-westerly winds without leading to corresponding changes in C. finmarchicus abundance in the North Sea, because the NSDW overflow responds over longer (decadal) time scales

Clastic Polygonal Networks Around Lyot Crater, Mars: Possible Formation Mechanisms From Morphometric Analysis

Polygonal networks of patterned ground are a common feature in cold-climate environments. They can form through the thermal contraction of ice-cemented sediment (i.e. formed from fractures), or the freezing and thawing of ground ice (i.e. formed by patterns of clasts, or ground deformation). The characteristics of these landforms provide information about environmental conditions. Analogous polygonal forms have been observed on Mars leading to inferences about environmental conditions. We have identified clastic polygonal features located around Lyot crater, Mars (50°N, 30°E). These polygons are unusually large (> 100 m diameter) compared to terrestrial clastic polygons, and contain very large clasts, some of which are up to 15 metres in diameter. The polygons are distributed in a wide arc around the eastern side of Lyot crater, at a consistent distance from the crater rim. Using high-resolution imaging data, we digitised these features to extract morphological information. These data are compared to existing terrestrial and Martian polygon data to look for similarities and differences and to inform hypotheses concerning possible formation mechanisms. Our results show the clastic polygons do not have any morphometric features that indicate they are similar to terrestrial sorted, clastic polygons formed by freeze-thaw processes. They are too large, do not show the expected variation in form with slope, and have clasts that do not scale in size with polygon diameter. However, the clastic networks are similar in network morphology to thermal contraction cracks, and there is a potential direct Martian analogue in a sub-type of thermal contraction polygons located in Utopia Planitia. Based upon our observations, we reject the hypothesis that polygons located around Lyot formed as freeze-thaw polygons and instead an alternative mechanism is put forward: they result from the infilling of earlier thermal contraction cracks by wind-blown material, which then became compressed and/or cemented resulting in a resistant fill. Erosion then leads to preservation of these polygons in positive relief, while later weathering results in the fracturing of the fill material to form angular clasts. These results suggest that there was an extensive area of ice-rich terrain, the extent of which is linked to ejecta from Lyot crater

Identification of VEGF-regulated genes associated with increased lung metastatic potential: functional involvement of tenascin-C in tumor growth and lung metastasis

Metastasis is the primary cause of death in patients with breast cancer. Overexpression of c-myc in humans correlates with metastases, but transgenic mice only show low rates of micrometastases. We have generated transgenic mice that overexpress both c-myc and vascular endothelial growth factor (VEGF) (Myc/VEGF) in the mammary gland, which develop high rates of pulmonary macrometastases. Gene expression profiling revealed a set of deregulated genes in Myc/VEGF tumors compared to Myc tumors associated with the increased metastatic phenotype. Cross-comparisons between this set of genes with a human breast cancer lung metastasis gene signature identified five common targets: tenascin-C(TNC), matrix metalloprotease-2, collagen-6-A1, mannosidase-alpha-1A and HLA-DPA1. Signaling blockade or knockdown of TNC in MDA-MB-435 cells resulted in a significant impairment of cell migration and anchorage-independent cell proliferation. Mice injected with clonal MDA-MB-435 cells with reduced expression of TNC demonstrated a significant decrease (P<0.05) in (1) primary tumor growth; (2) tumor relapse after surgical removal of the primary tumor and (3) incidence of lung metastasis. Our results demonstrate that VEGF induces complex alterations in tissue architecture and gene expression. The TNC signaling pathway plays an important role in mammary tumor growth and metastases, suggesting that TNC may be a relevant target for therapy against metastatic breast cancer

High-­resolution bio-­ and chemostratigraphy of an expanded record of Oceanic Anoxic Event 2 (Late Cenomanian–Early Turonian) at Clot Chevalier, near Barrême, SE France (Vocontian Basin, SE France)

A newly located exposure of the Niveau Thomel, an organic-­‐rich level at the Cenomanian–Turonian boundary, provides a highly expanded record of Oceanic Anoxic Event (OAE) 2, excepted for the lower relatively condensed glauconite-­rich part of the section. The new locality, close to Barrême in the Vocontian Basin, SE France, is developed in deep-­water hemi-­pelagic facies (shales, marls, marly limestones, variably enriched in organic matter) and provides an improved understanding of palaeoceanographic events associated with OAE 2. Investigation of the biostratigraphy (nannofossils and planktonic foramininfera), organic and inorganic geochemistry (bulk carbonate δ18O, total organic carbon (TOC), bulk organic, biomarker-specific and carbonate δ13C, major and trace elements, and Rock-­Eval data) has allowed characterization of the sediments in great detail. The combined study further constrains the detailed relationship between bio-­ and chemostratigraphy (particularly with respect to the details of the well-­displayed positive carbon-­‐isotope excursion) for this interval. The section also provides new evidence, in the form of a positive oxygen-­isotope excursion and an offset between carbonate and organic-­carbon carbon-­isotope records, which confirms the importance of cooling accompanied by a drop in dissolved CO2 in near-­surface waters during the Plenus Cold Event that characterized the early part of OAE 2. Evidence for increased oxygenation of bottom waters, together with elevated concentrations of redox-­sensitive and chalcophilic elements registered elsewhere through the level of the Plenus Cold Event, may be reflected in enhanced concentrations of iron (in glauconite) and nickel in coeval strata from the Clot Chevalier section

A Bayesian analysis of pentaquark signals from CLAS data

We examine the results of two measurements by the CLAS collaboration, one of which claimed evidence for a $\Theta^{+}$ pentaquark, whilst the other found no such evidence. The unique feature of these two experiments was that they were performed with the same experimental setup. Using a Bayesian analysis we find that the results of the two experiments are in fact compatible with each other, but that the first measurement did not contain sufficient information to determine unambiguously the existence of a $\Theta^{+}$. Further, we suggest a means by which the existence of a new candidate particle can be tested in a rigorous manner.Comment: 5 pages, 3 figure

First measurement of direct f0(980)f_0(980) photoproduction on the proton

We report on the results of the first measurement of exclusive $f_0(980)$ meson photoproduction on protons for $E_\gamma=3.0 - 3.8$ GeV and $-t = 0.4-1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the $\pi^+ \pi^-$ channel by performing a partial wave analysis of the reaction $\gamma p \to p \pi^+ \pi^-$. Clear evidence of the $f_0(980)$ meson was found in the interference between $P$ and $S$ waves at $M_{\pi^+ \pi^-}\sim 1$ GeV. The $S$-wave differential cross section integrated in the mass range of the $f_0(980)$ was found to be a factor of 50 smaller than the cross section for the $\rho$ meson. This is the first time the $f_0(980)$ meson has been measured in a photoproduction experiment

A branching, positive relief network in the middle member of the Medusae Fossae Formation, Equatorial Mars - evidence for sapping?

The Medusae Fossae Formation (MFF) is a geological formation comprising three geological units (members) spread across five principal lobes. It dominates a quarter of the longitudinal extent of the equatorial region of Mars. Positive relief features referred to as ‘sinuous ridges' (commonly interpreted as inverted paleoflow channel or valley fills) have been observed in the lowest member of the western MFF, but have not been identified within the central and eastern portions of the formation, in the middle and upper members. This paper presents the identification and analysis of a branching, positive relief system which occurs in the central lobe of the MFF in what appears to be an exposure of the middle member. A simple geomorphological map of the system is presented, from which we have adopted the working hypothesis that this is an inverted fill of a branching fluvial channel or valley system. A suite of morphological and topographic evidence supporting this hypothesis is presented, including analysis of the network using a~15 m per pixel digital terrain model derived from a Context Imager (CTX) stereo image pair. The evidence supporting this hypothesis includes: 1) The local slope and topography of the upper surface of the network are consistent with a contributory network, 2) The braided, fan-like form at the termination of the branching network is consistent in morphology with it being a depositional fan at the end of a fluvial system, 3) The terminal fan and surrounding deposits show layering and polygonization, 4) There is strong association between the lower order branches and amphitheater shaped scarps in the depression walls. We evaluate the possible origins of this fluvial system and suggest that seepage sapping is the most probable. Two possible models for the evolution of the network and related features are presented; both require melt of ice within the MFF to form liquid water. We conclude that at least some portions of the Medusae Fossae Formation, if not the entire formation, were once volatile-rich. Finally, we note that our observations do not rule out the case that this network formed before MFF emplacement, and has since been exhumed. However, this conclusion would suggest that much of the surrounding terrain, currently mapped as middle-member MFF, is not in fact MFF material at all