Late Miocene to early Pliocene biofacies of Wanganui and Taranaki Basins, New Zealand: Applications to paleoenvironmental and sequence stratigraphic analysis

The Matemateaonga Formation is late Miocene to early Pliocene (upper Tongaporutuan to lower Opoitian New Zealand Stages) in age. The formation comprises chiefly shellbeds, siliciclastic sandstone, and siltstone units and to a lesser extent non-marine and shallow marine conglomerate and rare paralic facies. The Matemateaonga Formation accumulated chiefly in shelf paleoenvironments during basement onlap and progradation of a late Miocene to early Pliocene continental margin wedge in the Wanganui and Taranaki Basins. The formation is strongly cyclothemic, being characterised by recurrent vertically stacked facies successions, bounded by sequence boundaries. These facies accumulated in a range of shoreface to mid-outer shelf paleoenvironments during conditions of successively oscillating sea level. This sequential repetition of facies and the biofacies they enclose are the result of sixth-order glacio-eustatic cyclicity. Macrofaunal associations have been identified from statistical analysis of macrofossil occurrences collected from multiple sequences. Each association is restricted to particular lithofacies and stratal positions and shows a consistent order and/or position within the sequences. This pattern of temporal paleoecologic change appears to be the result of lateral, facies-related shifting of broad biofacies belts, or habitat-tracking, in response to fluctuations of relative sea level, sediment flux, and other associated paleoenvironmental variables. The associations also show strong similarity in terms of their generic composition to biofacies identified in younger sedimentary strata and the modern marine benthic environment in New Zealand

Winding Number Correlation Functions and Cosmic String Formation

We develop winding number correlation functions that allow us to assess the role of field fluctuations on vortex formation in an Abelian gauge theory. We compute the behavior of these correlation functions in simple circumstances and show how fluctuations are important in the vicinity of the phase transition. We further show that, in our approximation, the emerging population of long/infinite string is produced by the classical dynamics of the fields alone, being essentially unaffected by field fluctuations.Comment: Latex file, 27 pages. 8 figures, available in compressed form by anonymous ftp from ftp://euclid.tp.ph.ic.ac.uk/papers/94-5_39.fig Latex and postscript versions also available at http://euclid.tp.ph.ic.ac.uk/Papers/index.htm

Wildfire and Abrupt Ecosystem Disruption on California\u27s Northern Channel Islands at the Allerod-Younger Dryas Boundary (13.0-12.9 ka)

Sedimentary records from California\u27s Northern Channel Islands and the adjacent Santa Barbara Basin (SBB) indicate intense regional biomass burning (wildfire) at the Ållerød–Younger Dryas boundary (~13.0–12.9 ka) (All age ranges in this paper are expressed in thousands of calendar years before present [ka]. Radiocarbon ages will be identified and clearly marked “14C years”.). Multiproxy records in SBB Ocean Drilling Project (ODP) Site 893 indicate that these wildfires coincided with the onset of regional cooling and an abrupt vegetational shift from closed montane forest to more open habitats. Abrupt ecosystem disruption is evident on the Northern Channel Islands at the Ållerød–Younger Dryas boundary with the onset of biomass burning and resulting mass sediment wasting of the landscape. These wildfires coincide with the extinction of Mammuthus exilis [pygmy mammoth]. The earliest evidence for human presence on these islands at 13.1–12.9 ka (~11,000–10,900 14C years) is followed by an apparent 600–800 year gap in the archaeological record, which is followed by indications of a larger-scale colonization after 12.2 ka. Although a number of processes could have contributed to a post 18 ka decline in M. exilis populations (e.g., reduction of habitat due to sea-level rise and human exploitation of limited insular populations), we argue that the ultimate demise of M. exilis was more likely a result of continental scale ecosystem disruption that registered across North America at the onset of the Younger Dryas cooling episode, contemporaneous with the extinction of other megafaunal taxa. Evidence for ecosystem disruption at 13–12.9 ka on these offshore islands is consistent with the Younger Dryas boundary cosmic impact hypothesis [Firestone, R.B., West, A., Kennett, J.P., Becker, L., Bunch, T.E., Revay, Z.S., Schultz, P.H., Belgya, T., Kennett, D.J., Erlandson, J.M., Dickenson, O.J., Goodyear, A.A., Harris, R.S., Howard, G.A., Kloosterman, J.B., Lechler, P., Mayewski, P.A., Montgomery, J., Poreda, R., Darrah, T., Que Hee, S.S., Smith, A.R., Stich, A., Topping, W., Wittke, J.H. Wolbach, W.S., 2007. Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and Younger Dryas cooling. Proceedings of the National Academy of Sciences 104, 16016–16021.]

Interactions between U(1)U(1) Cosmic Strings: An Analytical Study

We derive analytic expressions for the interaction energy between two general $U(1)$ cosmic strings as the function of their relative orientation and the ratio of the coupling constants in the model. The results are relevant to the statistic description of strings away from critical coupling and shed some light on the mechanisms involved in string formation and the evolution of string networks.Comment: 31 pages,REVTEX, Imperial/TP/93-94/3

B–N/B–H Transborylation: borane-catalysed nitrile hydroboration

The reduction of nitriles to primary amines is a useful transformation in organic synthesis, however, it often relies upon stoichiometric reagents or transition-metal catalysis. Herein, a borane-catalysed hydroboration of nitriles to give primary amines is reported. Good yields (48–95%) and chemoselectivity (e.g., ester, nitro, sulfone) were observed. DFT calculations and mechanistic studies support the proposal of a double B–N/B–H transborylation mechanism

Intrinsic challenges in ancient microbiome reconstruction using 16S rRNA gene amplification.

To date, characterization of ancient oral (dental calculus) and gut (coprolite) microbiota has been primarily accomplished through a metataxonomic approach involving targeted amplification of one or more variable regions in the 16S rRNA gene. Specifically, the V3 region (E. coli 341-534) of this gene has been suggested as an excellent candidate for ancient DNA amplification and microbial community reconstruction. However, in practice this metataxonomic approach often produces highly skewed taxonomic frequency data. In this study, we use non-targeted (shotgun metagenomics) sequencing methods to better understand skewed microbial profiles observed in four ancient dental calculus specimens previously analyzed by amplicon sequencing. Through comparisons of microbial taxonomic counts from paired amplicon (V3 U341F/534R) and shotgun sequencing datasets, we demonstrate that extensive length polymorphisms in the V3 region are a consistent and major cause of differential amplification leading to taxonomic bias in ancient microbiome reconstructions based on amplicon sequencing. We conclude that systematic amplification bias confounds attempts to accurately reconstruct microbiome taxonomic profiles from 16S rRNA V3 amplicon data generated using universal primers. Because in silico analysis indicates that alternative 16S rRNA hypervariable regions will present similar challenges, we advocate for the use of a shotgun metagenomics approach in ancient microbiome reconstructions

Redox‐controlled preservation of organic matter during “OAE 3” within the Western Interior Seaway

During the Cretaceous, widespread black shale deposition occurred during a series of Oceanic Anoxic Events (OAEs). Multiple processes are known to control the deposition of marine black shales, including changes in primary productivity, organic matter preservation, and dilution. OAEs offer an opportunity to evaluate the relative roles of these forcing factors. The youngest of these events—the Coniacian to Santonian OAE 3—resulted in a prolonged organic carbon burial event in shallow and restricted marine environments including the Western Interior Seaway. New high‐resolution isotope, organic, and trace metal records from the latest Turonian to early Santonian Niobrara Formation are used to characterize the amount and composition of organic matter preserved, as well as the geochemical conditions under which it accumulated. Redox sensitive metals (Mo, Mn, and Re) indicate a gradual drawdown of oxygen leading into the abrupt onset of organic carbon‐rich (up to 8%) deposition. High Hydrogen Indices (HI) and organic carbon to total nitrogen ratios (C:N) demonstrate that the elemental composition of preserved marine organic matter is distinct under different redox conditions. Local changes in δ13C indicate that redox‐controlled early diagenesis can also significantly alter δ13Corg records. These results demonstrate that the development of anoxia is of primary importance in triggering the prolonged carbon burial in the Niobrara Formation. Sea level reconstructions, δ18O results, and Mo/total organic carbon ratios suggest that stratification and enhanced bottom water restriction caused the drawdown of bottom water oxygen. Increased nutrients from benthic regeneration and/or continental runoff may have sustained primary productivity.Key PointsBottom water redox changes triggered carbon burial within the WIS during OAE 3Anoxia developed due to O2 drawdown in a stratified water columnRedox‐controlled changes in OM preservation altered primary δ13Corg signalsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112294/1/palo20210.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112294/2/palo20210-sup-0001-SupportingInfo.pd

Twin Town in South Brazil: A Nazi's Experiment or a Genetic Founder Effect?

Cândido Godói (CG) is a small municipality in South Brazil with approximately 6,000 inhabitants. It is known as the “Twins' Town” due to its high rate of twin births. Recently it was claimed that such high frequency of twinning would be connected to experiments performed by the German Nazi doctor Joseph Mengele. It is known, however, that this town was founded by a small number of families and therefore a genetic founder effect may represent an alternatively explanation for the high twinning prevalence in CG. In this study, we tested specific predictions of the “Nazi's experiment” and of the “founder effect” hypotheses. We surveyed a total of 6,262 baptism records from 1959–2008 in CG catholic churches, and identified 91 twin pairs and one triplet. Contrary to the “Nazi's experiment hypothesis”, there is no spurt in twinning between the years (1964–1968) when Mengele allegedly was in CG (P = 0.482). Moreover, there is no temporal trend for a declining rate of twinning since the 1960s (P = 0.351), and no difference in twinning among CG districts considering two different periods: 1927–1958 and 1959–2008 (P = 0.638). On the other hand, the “founder effect hypothesis” is supported by an isonymy analysis that shows that women who gave birth to twins have a higher inbreeding coefficient when compared to women who never had twins (0.0148, 0.0081, respectively, P = 0.019). In summary, our results show no evidence for the “Nazi's experiment hypothesis” and strongly suggest that the “founder effect hypothesis” is a much more likely alternative for explaining the high prevalence of twinning in CG. If this hypothesis is correct, then this community represents a valuable population where genetic factors linked to twinning may be identified

Rec-DCM-Eigen: Reconstructing a Less Parsimonious but More Accurate Tree in Shorter Time

Maximum parsimony (MP) methods aim to reconstruct the phylogeny of extant species by finding the most parsimonious evolutionary scenario using the species' genome data. MP methods are considered to be accurate, but they are also computationally expensive especially for a large number of species. Several disk-covering methods (DCMs), which decompose the input species to multiple overlapping subgroups (or disks), have been proposed to solve the problem in a divide-and-conquer way