Blood thicker than water: Kinship, disease prevalence and group size drive divergent patterns of infection risk in a social mammal

The importance of social- and kin-structuring of populations for the transmission of wildlife disease is widely assumed but poorly described. Social structure can help dilute risks of transmission for group members, and is relatively easy to measure, but kin-association represents a further level of population sub-structure that is harder to measure, particularly when association behaviours happen underground. Here, using epidemiological and molecular genetic data from a wild, high-density population of the European badger (Meles meles), we quantify the risks of infection with Mycobacterium bovis (the causative agent of tuberculosis) in cubs. The risk declines with increasing size of its social group, but this net dilution effect conceals divergent patterns of infection risk. Cubs only enjoy reduced risk when social groups have a higher proportion of test-negative individuals. Cubs suffer higher infection risk in social groups containing resident infectious adults, and these risks are exaggerated when cubs and infectious adults are closely related. We further identify key differences in infection risk associated with resident infectious males and females. We link our results to parent– offspring interactions and other kin-biased association, but also consider the possibility that susceptibility to infection is heritable. These patterns of infection risk help to explain the observation of a herd immunity effect in badgers following low-intensity vaccination campaigns. They also reveal kinship and kin-association to be important, and often hidden, drivers of disease transmission in social mammals

CamouflageFS: Increasing the Effective Key Length in Cryptographic Filesystems on the Cheap

One of the few quantitative metrics used to evaluate the security of a cryptographic file system is the key length of the encryption algorithm; larger key lengths correspond to higher resistance to brute force and other types of attacks. Since accepted cryptographic design principles dictate that larger key lengths also impose higher processing costs, increasing the security of a cryptographic file system also increases the overhead of the underlying cipher. We present a general approach to effectively extend the key length without imposing the concomitant processing overhead. Our scheme is to spread the ciphertext inside an artificially large file that is seemingly filled with random bits according to a key-driven spreading sequence. Our prototype implementation, CamouflageFS, offers improved performance relative to a cipher with a larger key-schedule, while providing the same security properties. We discuss our implementation (based on the Linux Ext2 file system) and present some preliminary performance results. While CamouflageFS is implemented as a stand-alone file system, its primary mechanisms can easily be integrated into existing cryptographic file systems

Post-weaning and whole-of-life performance of pigs is determined by live weight at weaning and the complexity of the diet fed after weaning

The production performance and financial outcomes associated with weaner diet complexity for pigs of different weight classes at weaning were examined in this experiment. A total of 720 weaner pigs (360 entire males and 360 females) were selected at weaning (27 ± 3 d) and allocated to pens of 10 based on individual weaning weight (light weaning weight: pigs below 6.5 kg; medium weaning weight: 6.5 to 8 kg; heavy weaning weight: above 8.5 kg). Pens were then allocated in a 3 × 2 × 2 factorial arrangement of treatments with the respective factors being weaning weight (heavy, medium and light; H, M and L, respectively), weaner diet complexity (high complexity/cost, HC; low complexity/cost, LC), and gender (male and female). Common diets were fed to both treatment groups during the final 4 weeks of the weaner period (a period of 39 days). In the first 6 d after weaning, pigs offered the HC diets gained weight faster and used feed more efficiently than those offered the LC diets (P = 0.031). Pigs fed a HC diet after weaning tended to be heavier at the sale live weight of 123 d of age compared with pigs fed the LC diet (P = 0.056). There were no other main effects of the feeding program on growth performance through to slaughter. Weaning weight had a profound influence on lifetime growth performance and weight at 123 d of age, with H pigs at weaning increasing their weight advantage over the M and L pigs (101.3, 97.1, 89.6 kg respectively, P < 0.001). Cost-benefit analyses suggested there was a minimal benefit in terms of cost per unit live weight gain over lifetime when pigs were offered a HC feeding program to L, with a lower feed cost/kg gain. The results from this investigation confirm the impact of weaning weight on lifetime growth performance, and suggest that a HC feeding program should be focused on L weaner pigs (i.e., weaning weight less than 6.5 kg at 27 d of age) in order to maximise financial returns

Economic benefits of feeding high cost weaner diets are maximised when offered to pigs less than 6.5 kg at weaning

Growth performance is typically reduced in the period immediately post weaning while the piglet adapts to the new environment and feed source. This reduction in growth performance can negatively affect lifetime performance (Tokach et al., 1992). The use of high cost weaner diets during the first three weeks post-weaning is extensively practised to reduce the growth check and enhance performance to slaughter. It is hypothesized that the weight of the piglet at weaning will influence the growth performance and economic benefits from such a feeding program. Therefore, the aim of this study was to evaluate the benefits of feeding high cost weaner diets during the period immediately post weaning for pigs of different weaning weights

Big Bang Nucleosynthesis with Gaussian Inhomogeneous Neutrino Degeneracy

We consider the effect of inhomogeneous neutrino degeneracy on Big Bang nucleosynthesis for the case where the distribution of neutrino chemical potentials is given by a Gaussian. The chemical potential fluctuations are taken to be isocurvature, so that only inhomogeneities in the electron chemical potential are relevant. Then the final element abundances are a function only of the baryon-photon ratio $\eta$, the effective number of additional neutrinos $\Delta N_\nu$, the mean electron neutrino degeneracy parameter $\bar \xi$, and the rms fluctuation of the degeneracy parameter, $\sigma_\xi$. We find that for fixed $\eta$, $\Delta N_\nu$, and $\bar \xi$, the abundances of helium-4, deuterium, and lithium-7 are, in general, increasing functions of $\sigma_\xi$. Hence, the effect of adding a Gaussian distribution for the electron neutrino degeneracy parameter is to decrease the allowed range for $\eta$. We show that this result can be generalized to a wide variety of distributions for $\xi$.Comment: 9 pages, 3 figures, added discussion of neutrino oscillations, altered presentation of figure

Factors Influencing the Participation of Older People in Clinical Trials : Data Analysis from the MAVIS Trial

Peer reviewedPostprin

The calibration of the Sudbury Neutrino Observatory using uniformly distributed radioactive sources

The production and analysis of distributed sources of 24Na and 222Rn in the Sudbury Neutrino Observatory (SNO) are described. These unique sources provided accurate calibrations of the response to neutrons, produced through photodisintegration of the deuterons in the heavy water target, and to low energy betas and gammas. The application of these sources in determining the neutron detection efficiency and response of the 3He proportional counter array, and the characteristics of background Cherenkov light from trace amounts of natural radioactivity is described.Comment: 24 pages, 13 figure

On the Potts model partition function in an external field

We study the partition function of Potts model in an external (magnetic) field, and its connections with the zero-field Potts model partition function. Using a deletion-contraction formulation for the partition function Z for this model, we show that it can be expanded in terms of the zero-field partition function. We also show that Z can be written as a sum over the spanning trees, and the spanning forests, of a graph G. Our results extend to Z the well-known spanning tree expansion for the zero-field partition function that arises though its connections with the Tutte polynomial

CUORE: A Cryogenic Underground Observatory for Rare Events

CUORE is a proposed tightly packed array of 1000 TeO2 bolometers, each being a cube 5 cm on a side with a mass of 760 g. The array consists of 25 vertical towers, arranged in a square of 5 towers by 5 towers, each containing 10 layers of 4 crystals. The design of the detector is optimized for ultralow-background searches: for neutrinoless double beta decay of 130Te (33.8% abundance), cold dark matter, solar axions, and rare nuclear decays. A preliminary experiment involving 20 crystals 3x3x6 cm3 of 340 g has been completed, and a single CUORE tower is being constructed as a smaller scale experiment called CUORICINO. The expected performance and sensitivity, based on Monte Carlo simulations and extrapolations of present results, are reported.Comment: 39 pages, 12 figures, submitted to NI