A deep-sea coral record of North Atlantic radiocarbon through the Younger Dryas: Evidence for intermediate water/deepwater reorganization

Our record of Younger Dryas intermediate-depth seawater Δ^(14)C from North Atlantic deep-sea corals supports a link between abrupt climate change and intermediate ocean variability. Our data show that northern source intermediate water (∼1700 m) was partially replaced by (14)^C-depleted southern source water at the onset of the event, consistent with a reduction in the rate of North Atlantic Deep Water formation. This transition requires the existence of large, mobile gradients of Δ^(14)C in the ocean during the Younger Dryas. The Δ^(14)C water column profile from Keigwin (2004) provides direct evidence for the presence of one such gradient at the beginning of the Younger Dryas (∼12.9 ka), with a 100‰ offset between shallow (<∼2400 m) and deep water. Our early Younger Dryas data are consistent with this profile and also show a Δ^(14)C inversion, with 35‰ more enriched water at ∼2400 m than at ∼1700 m. This feature is probably the result of mixing between relatively well ^(14)C ventilated northern source water and more poorly ^(14)C ventilated southern source intermediate water, which is slightly shallower. Over the rest of the Younger Dryas our intermediate water/deepwater coral Δ^(14)C data gradually increase, while the atmosphere Δ^(14)C drops. For a very brief interval at ∼12.0 ka and at the end of the Younger Dryas (11.5 ka), intermediate water Δ^(14)C (∼1200 m) approached atmospheric Δ14C. These enriched Δ^(14)C results suggest an enhanced initial Δ^(14)C content of the water and demonstrate the presence of large lateral Δ^(14)C gradients in the intermediate/deep ocean in addition to the sharp vertical shift at ∼2500 m. The transient Δ^(14)C enrichment at ∼12.0 ka occurred in the middle of the Younger Dryas and demonstrates that there is at least one time when the intermediate/deep ocean underwent dramatic change but with much smaller effects in other paleoclimatic records

High-resolution record of climate change in the Owens Lake Basin, California, for the period 52,500 to 12,500 YBP

EXTRACT (SEE PDF FOR FULL ABSTRACT): High-resolution oxygen-18 and total inorganic carbon (TIC) studies of cored sediments from the Owens Lake Basin, California, indicate that Owens Lake was hydrologically open (overflowing) most of the time between 52,500 and 12,500 carbon-14 YBP. ... The lack of a strong correspondence between North Atlantic climate records and the Owens Lake delta-oxygen-18 record has two possible explanations: (1) the sequence of large and abrupt climate change indicated in North Atlantic records is not global in scope and is largely confined to the North Atlantic and surrounding areas, or (2) Owens Lake is located in a part of the Great Basin that is relatively insensitive to the effects of climate perturbations recorded in the North Atlantic region

Radiocarbon dating of deep-sea corals

Deep-sea corals are a promising new archive of paleoclimate. Coupled radiocarbon and U-series dates allow ^(14)C to be used as a tracer of ocean circulation rate in the same manner as it is used in the modern ocean. Diagnetic alteration of coral skeletons on the seafloor requires a thorough cleaning of contaminating phases of carbon. In addition, 10% of the coral must be chemically leached prior to dissolution to remove adsorbed modern CO_2. A survey of modern samples from the full Δ^(14)C gradient in the deep ocean demonstrates that the coralline CaCO_3 records the radiocarbon value of the dissolved inorganic carbon

Media structure of social collectivities in Latin America: the case of Uruguay, Argentina, Ecuador and Bolivia

Los medios comunitarios, especialmente en el ámbito de la radio, son una tradición en América Latina y su aporte es muy significativo para la democracia y como forma de expresión de sectores de la población de menos recursos. Destacamos la situación en Uruguay, Argentina, Ecuador y Bolivia, cuyo impulso normativo lidera en el continente la democratización del acceso al espectro, aunque como hemos comprobado su desarrollo legislativo y estructural todavía no se ha completado. Dada esta premisa, las técnicas de investigación que se han manejado han sido el análisis documental de fuentes bibliográficas y hemerográficas, y la conversación personal directa.The existence of community media, especially in the field of radio, is a long tradition in Latin America and its contribution is very significant, both for democracy and forms of expression of vast sectors of the population with fewer resources. However, this reality has not always been accompanied by legal recognition by states as a sector with the same opportunities as public or private media. However, it is notorious that there has been a significant advance in the recognition of community media in the region. In this text we highlight the situation in Uruguay, Argentina, Ecuador and Bolivia, whose normative impulse leads in the continent the democratization of spectrum access, although as we have proven its legislative and structural development has not yet been completed. In the search for this reality in this text we have tried an inductive approach to our object of study with the intention of finding those elements that best allow us to describe and analyze it. Given this premise, the research techniques that have been handled have been, essentially, the documentary analysis of diverse sources, among them the bibliographic and the hemerographic ones, and the direct personal conversation.Ciencias de la Comunicació

Heterodimetallic germanium(IV) complex structures with transition metals

The hydrothermal synthesis and structural characterization of a number of complex compounds containing the divalent tris(oxalato-O,O¢)germanate anion, [Ge(C2O4)3]2-, or the neutral bis(oxalate-O,O¢)germanium fragment, [Ge(C2O4)2], with transition-metal (M) cationic complexes of 1,10¢-phenanthroline (phen) is reported: [M(phen)3]- [Ge(C2O4)3]âxH2O [where M2+ ) Cu2+ (1a and 1b), Fe2+ (2a and 2b), Ni2+ (3), Co2+ (4); x ) 0.2 for 2b], [MGe- (phen)2(í2-OH)2(C2O4)2] [where M2+ ) Cd2+ (5) and Cu2+ (6)]. The isolation of two polymorphs with Cu2+ (1a and 1b) and other pseudo-polymorphs for Fe2+ (2a and 2b) was rationalized based on slightly different molar ratios for the starting materials. All compounds have been characterized using EDS, SEM, vibrational spectroscopy (FT-IR and FT-Raman), thermogravimetry, and CHN elemental composition and their structure determined on the basis of single-crystal X-ray diffraction studies. The crystal packing of the different chemical moieties for each series of compounds was discussed on the basis of the various intermolecular interactions present (strong C-Hâââð and weak C-HâââO hydrogen-bonding interactions, C-Hâââð and ð-ð contacts).FCT - SFRH/BPD/9309/2002FCT - SFRH/BPD/14410/2003FEDERPOCI - 201

Homochiral self-sorted and emissive IrIII metallo-cryptophanes

We thank the EPSRC (DTG award 1238852, EP/K039202/1, EP/M02105X/1, EP/J001325/1), Leverhulme Trust (RPG-2014-148), University of St Andrews, and the MEXT/JSPS Grants in Aid for Scientific Research (JP25102005 and JP25102001) for funding; Simon Barrett for assistance with NMR; Martin Huscroft for assistance with HPLC, and Stephen Boyer for elemental analysis measurements.The racemic ligands (±)-tris(isonicotinoyl)-cyclotriguaiacylene (L1), or (±)-tris(4-pyridyl-methyl)-cyclotriguaiacylene (L2) assemblewith racemic (Λ, Δ)- [Ir(ppy)2(MeCN)2]+, in which ppy = 2-phenylpyridinato to form [{Ir(ppy)2}3(L)2]3+ metallo-cryptophane cages. The crystal structure of [{Ir(ppy)2}3(L1)2]∙3BF4 has MM-ΛΛΛ nd PP-ΔΔΔ isomers, and homochiral self-sorting occurs in solution, a processaccelerated by a chiral guest. Self-recognition between L1 and L2 within cagesdoes not occur, and cages show very slow ligand-exchange. Both cages are phosphorescent,with [{Ir(ppy)2}3(L2)2]3+ havingenhanced and blue-shifted emission when compared with [{Ir(ppy)2}3(L1)2]3+ .PostprintPeer reviewe

Supporting students with learning disabilities in the general education classroom

Current mandate of the Individuals with Disabilities Education Act places students with mild to moderate learning disabilities in the least restrictive environment to the maximum extent possible with general education students. At the secondary level, this mandate challenges both general education teachers and students with mild to moderate learning disabilities. The purpose of this study is to understand the needs of students with mild to moderate learning disabilities and their general education teachers in an effort to move toward academic engagement and achievement through differentiated instruction. This study took place in a small coastal California high school where teachers were surveyed about their knowledge, understanding, and implementation of differentiated instruction. A teacher’s focus group was also formed and met with the researcher in an effort to determine a better understanding of the principles and support needed for practicing differentiated instruction. Finally, high school students with mild to moderate learning disabilities were interviewed to determine the support they perceived as essential for achieving academic success in general education classrooms. The results showed that while many of the teachers knew the principles and components of differentiated instruction, many of the myths were also believed to be true. During the focus group many of the common barriers to inclusion were found to be present. A lack of time to plan for differentiated instruction proved to be the most frequently mentioned barrier. The most common need for students with mild to moderate learning disabilities was for general education teachers to be aware of the students’ different learning styles so their strengths could be utilized and appreciated. This was closely followed by the need for approachable teachers and friends to satisfy the feeling of community and belonging. Until schools begin to identify ways to truly include students with mild to moderate learning disabilities in general educat! ion clas srooms, the likelihood increases that genuine inclusion will not take place

Mechanisms of IRF-1 Induced Cancer Growth Inhibition

The tumor suppressor IRF-1 has been gaining interest as a mediator of anticancer therapies and its role in mediating apoptosis and cell cycle arrest are currently being elucidated. Through the creation of recombinant adenoviral (Ad-) IRF-1 in our lab, we are in a unique position to study the underlying mechanisms of IRF-1 mediated tumor growth inhibition. First, we will further determine the role of IRF-1 in caspase-mediated apoptosis. Our work will examine the mechanism of IRF-1 activation of initiator caspase 8 and effector caspases 3 and 7 and the role of soluble factors. Our second course of study will delineate the role of IRF-1 mediated cell cycle effects and with a focus on G1 arrest and p21waf1cip1 upregulation. Our initial hypothesis that IRF-1 induces caspase 3/7 mediated apoptosis through a death receptor pathway in conjunction with the secretion of soluble factors in cancer was not supported by results obtained. We found that death ligands were not mediating IRF-1 growth inhibition; however we did find that the caspase cascade was clearly involved. Moreover, we have shown that caspase 8 activity is central in mediating IRF-1 apoptosis. While investigating the intrinsic pathway we made a novel discovery that IRF-1 localizes to the mitochondria. The significance of this finding is still under investigation.Studies of p21 knock down confirmed that IRF-1 utilizes p21 in p53 independent G1 cell cycle arrest. We hypothesized that cell cycle arrest would "protect" the cells from apoptosis but found that p21 up regulation by IRF-1 corresponded to caspase cleavage and that apoptosis was suppressed in our p21 knock down cell lines. We also found that the inhibitor of apoptosis, survivin may account for this effect. Finally, we show that IRF-1 growth inhibitory effects are directed to malignant and not normal breast cells. We show that this too may be linked to survivin which is commonly overexpressed in cancers and suppressed by IRF-1.Greater understanding of the mechanisms of IRF-1 cancer growth inhibition is significant to public health because it may allow better utilization and development of IRF-1 and agents that are mediated by IRF-1 in cancer treatment