Molecule formation as a diagnostic tool for second order correlations of ultra-cold gases

We calculate the momentum distribution and the second-order correlation function in momentum space, $g^{(2)}({\bf p},{\bf p}',t)$ for molecular dimers that are coherently formed from an ultracold atomic gas by photoassociation or a Feshbach resonance. We investigate using perturbation theory how the quantum statistics of the molecules depend on the initial state of the atoms by considering three different initial states: a Bose-Einstein condensate (BEC), a normal Fermi gas of ultra-cold atoms, and a BCS-type superfluid Fermi gas. The cases of strong and weak coupling to the molecular field are discussed. It is found that BEC and BCS states give rise to an essentially coherent molecular field with a momentum distribution determined by the zero-point motion in the confining potential. On the other hand, a normal Fermi gas and the unpaired atoms in the BCS state give rise to a molecular field with a broad momentum distribution and thermal number statistics. It is shown that the first-order correlations of the molecules can be used to measure second-order correlations of the initial atomic state.Comment: revtex, 15 pages,8 figure

Dutch (organic) agriculture, carbon sequestration and energy production

Carbon sequestration in soils is often mentioned in the discussions about climate changes. In this paper the opportunities for carbon sequestration in Dutch agriculture are discussed at farm and national level. Farm internal carbon sources are already completely used in livestock farming. The effect under arable conditions is limited in time and very limited compared to national CO2 emission. External sources are scarce. Energy production out of crop residues and manure via biogas installations is possible but the overall impact is again very limited. The effect of this biogas pathway on soil organic matter quantity and quality is not yet known. Organic arable farmers do already have a higher soil organic matter content than conventional farmers, partly due to external carbon sources. This puts them in a leading position. The disadvantage is that it is more difficult for them to do a next step in increasing soil organic matte

Folic Acid, Dietary Patterns and Perinatal Health: The Generation R Study

The perinatal mortality rate in The Netherlands is among the highest in the European Union, with one in 100 babies dying during pregnancy, at birth or shortly thereafter. Low birth weight, preterm birth, congenital anomalies, perinatal asphyxia, and pre-eclampsia are major contributors to perinatal mortality. Moreover, pre-eclampsia is not only a major driver for perinatal mortality but plays a significant role in maternal mortality as well

High Temperature Superfluid and Feshbach Resonance

We study an effective field theory describing cold fermionic atoms near a Feshbach resonance. The theory gives a unique description of the dynamics in the limit that the energy of the Feshbach resonance is tuned to be twice that of the Fermi surface. We show that in this limit the zero temperature superfluid condensate is of order the Fermi energy, and obtain a critical temperature $T_C \simeq 0.43 T_F$Comment: 9 pages, 3 figures, RevTe

Black rabbits on Lundy: Tudor treasures or post-war phonies?

Lundy is renowned for its feral black rabbits which, according to popular tradition, have inhabited the island since medieval times. Black rabbit fur was valued for much of the Middle Ages, explaining why warreners of Lundy might have favoured them, but genes responsible for feral rabbit melanism remain unexplored. Further potential complicating factors occur in the form of recent (twentieth century) small-scale domestic rabbit introductions to the Lundy feral population. To gain insight into genetic mechanisms underlying melanism on Lundy, rabbit samples were collected and subjected to molecular analysis. The Lundy rabbit population is shown to harbour non-functional copies of the agouti signalling protein (Asip) gene, a main determinant of coat colour in mammals. The observed genetic mutation is not unique to Lundy, having been reported to underlie dark coat colour phenotypes in various domestic rabbit breeds. The mutation is recessive and only phenotypically expressed in homozygous individuals. Although presence of this particular allele does not preclude recent genetic augmentation or replacement, simple population genetics show that allele persistence from a medieval introduction is not impossible

What's on the menu: Drosera rotundifolia diet determination using DNA data

The round-leaved sundew, Drosera rotundifolia, is a carnivorous plant species. On Lundy it is found in the nutrient-poor bog environments of Pondsbury and the northernmost quarry, where it supplements its diet with invertebrate prey. To gain insight into the diet of these two sundew populations a metabarcoding approach was trialled. This is, to our knowledge, the first study to use DNA barcodes to identify Drosera prey. At each site, a 0.25m2 quadrat was placed in a representative Drosera patch and two days’ worth of prey were collected. To identify prey items, Cytochrome c oxidase subunit I (COX1) sequences were obtained and compared to the Barcode of Life database. This revealed that Lundy sundews have a mixed diet. In total at least 20 different prey taxa were detected in the two 0.25m2 areas sampled. Sixteen taxa could be identified to species, indicating that metabarcoding permits accurate species level identification of sundew prey items. The majority of prey taxa were dipterans (two-winged flies), of which several have previously been reported on Lundy. Most prey taxa were detected in only one of the two quadrats examined (Jaccard’s index of Similarity=0.01; ‘dissimilar’). This might indicate that the two Drosera populations feed on distinct prey communities, but more research is needed to confirm this

Wolbachia and Spiroplasma endosymbionts in the Anurida maritima (Collembola) species group

A large proportion of arthropods carry maternally-inherited endosymbiotic bacteria with which they have developed close relationships. Some of these endosymbionts are selfish genetic elements and manipulate their hosts’ reproduction to their own advantage, for example via cytoplasmic incompatibility (CI) or male killing. Here we report that the sexually reproducing collembolan Anurida maritima carries two endosymbionts (Wolbachia and Spiroplasma) and provide genome sequences for both bacteria. Phylogenomic analyses indicate that the Wolbachia belong to the A supergroup and that the Spiroplasma are sister to the Citri-Chrysopicola-Mirum lineage. A. maritima is considered a species group and consists of at least two distinct genetic lineages. We show that both lineages carry both endosymbionts. No homologs of the Spiroplasma male-killing gene SpAID were observed within our datasets. Homologs of the male-killing associated wmk and the CI inducing cifA and cifB prophage genes were detected in the Wolbachia genome. Phylogenetic analyses placed the cif genes in the poorly characterised Type V clade. The cifA and cifB gene sequences of the two Anurida lineages are identical. It therefore seems unlikely that the genetic divergence within the species group stems from cifA and cifB induced CI. Laboratory controlled genetic crosses and sex ratio studies will be needed to reveal any potential effect of the two endosymbionts on A. maritima’s reproduction

Nature read in tooth and fur: non-invasive sampling of the Pygmy Shrew (Sorex minutus Linnaeus, 1766) on Lundy for population genetics

Britain’s smallest mammal, the pygmy shrew (Sorex minutus Linnaeus, 1766) is the only long established terrestrial mammal on Lundy. Little is known about this species’ mode of colonisation or its population structure on the island. Genetic analyses might provide useful insights in this respect, but DNA samples are difficult to obtain because pygmy shrews can be harmed by sampling methods. Two non invasive methods for obtaining DNA sequences were tested. DNA was extracted from hair samples and from a mandible derived from a bird-pellet. A 612 base pair fragment of the cytochrome oxidase b gene was PCR amplified and sequenced. To investigate the origin of pygmy shrew on Lundy the sequences were analysed in the context of published data. The sequences are most similar to those from the U.K. mainland which supports a British origin of this population