Climate-induced effects on the meroplankton and the benthic-pelagic ecology of the North Sea

Analyses of long-term time series of North Sea plankton and sea surface temperature (SST) data reveal that the annual planktonic larval abundance of three benthic phyla, Echinodermata, Arthropoda, and Mollusca, responds positively and immediately to SST. Long-term outcomes for the planktonic abundance of these three phyla are different, however. The planktonic larvae of echinoderms and decapod crustaceans have increased in abundance from 1958 to 2005, and especially since the mid-1980s, as North Sea SST has increased. In contrast, the abundance of bivalve mollusc larvae has declined, despite the positive year-to-year relationship between temperature and bivalve larval abundance continuing to hold. We argue that the changes in meroplankton abundance, coincident with increased phytoplankton and declining holoplankton, reflect the synchronous effect of rising SST and related changes in the pelagic community on the reproduction and recruitment of many benthic marine invertebrates. Under this scenario, the long-term decline in bivalve mollusc larvae will reflect increased predation on the settled larvae and adults by benthic decapods. These alterations in the zooplankton may therefore describe an ecosystem-wide restructuring of North Sea trophic interactions.

Correlates of reproductive success in a population of nine-banded armadillos: a preliminary report.

We used microsatellite DNA markers to identify the putative parents of 69 litters of nine-banded armadillos (Dasypus novemcinctus) over 4 years. Male and female parents did not differ in any measure of body size in comparisons with nonparents. However, males observed paired with a female were significantly larger than unpaired males, although paired females were the same size as unpaired females. Females categorized as possibly lactating were significantly larger than females that were either definitely lactating or definitely not lactating. There was no evidence of assortative mating: body-size measurements of mothers were not significantly correlated with those of fathers. Nine-banded armadillos give birth to litters of genetically identical quadruplets. Mothers (but not fathers) of female litters were significantly larger than mothers of male litters, and maternal (but not paternal) body size was positively correlated with the number of surviving young within years, but not cumulatively. There were no differences in dates of birth between male and female litters, nor were there any significant relationships between birth date and maternal body size. Body size of either parent was not correlated with the body sizes of their offspring. Cumulative and yearly reproductive success did not differ between reproductively successful males and females. Average reproductive success (which included apparently unsuccessful individuals) also did not differ between males and females. The majority of adults in the population apparently failed to produce any surviving offspring, and even those that did usually did so in only 1 of the 4 years. This low reproductive success is unexpected, given the rapid and successful range extension of this species throughout the southeastern United States in this century.

Development and mechanical characterization of bioadhesive semi-solid, polymeric systems containing tetracycline for the treatment of periodontal diseases

Purpose. This study examined the mechanical characteristics and release of tetracycline from bioadhesive, semi-solid systems which were designed for the treatment of periodontal diseases.

Entanglement of a two-mode squeezed state in a phase-sensitive Gaussian environment

Some non-classical properties such as squeezing, sub-Poissonian photon statistics or oscillations in photon-number distributions may survive longer in a phase-sensitive environment than in a phase-insensitive environment. We examine if entanglement, which is an inter-mode non-classical feature, can also survive longer in a phase-sensitive environment. Differently from the single-mode case, we find that making the environment phase-sensitive does not aid in prolonging the inter-mode non-classical nature, i.e. entanglement.

Atomistic Insights into Rhodopsin Activation from a Dynamic Model

Rhodopsin, the light sensitive receptor responsible for blue-green vision, serves as a prototypical G protein-coupled receptor (GPCR). Upon light absorption, it undergoes a series of conformational changes that lead to the active form, metarhodopsin II (META II), initiating a signaling cascade through binding to the G protein transducin (G(t)). Here, we first develop a structural model of META II by applying experimental distance restraints to the structure of lumi-rhodopsin (LUMI), an earlier intermediate. The restraints are imposed by using a combination of biased molecular dynamics simulations and perturbations to an elastic network model. We characterize the motions of the transmembrane helices in the LUMI-to-META II transition and the rearrangement of interhelical hydrogen bonds. We then simulate rhodopsin activation in a dynamic model to study the path leading from LUMI to our META II model for wild-type rhodopsin and a series of mutants. The simulations show a strong correlation between the transition dynamics and the pharmacological phenotypes of the mutants. These results help identify the molecular mechanisms of activation in both wild type and mutant rhodopsin. While static models can provide insights into the mechanisms of ligand recognition and predict ligand affinity, a dynamic model of activation could be applicable to study the pharmacology of other GPCRs and their ligands, offering a key to predictions of basal activity and ligand efficacy.

Marine reservoir corrections: St Helena, South Atlantic Ocean

We present the first marine reservoir age and Delta R determination for the island of St. Helena using marine mollusk radiocarbon dates obtained from an historical context of known age. This represents the first marine reservoir a.-c and Delta R determination in the southern Atlantic Ocean within thousands of kilometers of the island. The depletion of C-14 in the shells indicates a rather larger reservoir age for that portion of the surface Atlantic than models indicate. The implication is that upwelling old water along the Namibian coast is transported for a considerable distance, although it is likely to be variable on a decadal timescale. An artilleryman's button, together with other artifacts found in a midden, demonstrate association of the mollusk shells with a narrow historic period of AD 1815-1835.

James Anderson's Political Economy--His Influence on Smith and Malthus

James Anderson's powerful critique of Adam Smith's position on the corn export bounty was published in 1777. It focuse d on Smith's proposition that the bounty could not lead to increased corn production because it could not increase corn's real price. Smit h's response to the critique is traced in later editions of Wealth of Nations. While Anderson's critique of Smith influenced Thomas Malthu s's writings from 1803 onwards, his theory of differential rent did n ot influence Malthus at this stage. An examination of the evolution o f Malthus's ideas on rent between 1803 and 1815, however, indicates t hat Malthus knew and used Anderson's work on rent.