A spatially explicit habitat selection model incorporating home range behavior

Understanding habitat selection is of primary interest in theoretical and applied ecology. One approach is to infer habitat selection processes from differences in population densities between habitats using methods such as isodar and isoleg analysis. Another approach is to directly observe the movements of individuals. However, habitat selection models based on movement data often fail to adequately incorporate spatial processes. This is problematic if the probability of selecting a particular habitat is dependent upon its spatial context. This would occur, for example, where organisms exhibit home range behavior and the choice of habitat is dependent on its location relative to the home range. In this paper we present a spatially explicit habitat selection model for movement data that incorporates home range behavior as a spatial process. Our approach extends a previous model by formulating the probability of selecting a habitat as a function of its distance from the animal's current location and home range center. We demonstrate that these enhancements lead to more parsimonious models when applied to a koala radiotracking data set from eastern Australia. This approach could also be applied to modeling other spatial habitat selection processes, leading to more biologically meaningful models for a range of species and applications

First direct mass-measurement of the two-neutron halo nucleus 6He and improved mass for the four-neutron halo 8He

The first direct mass-measurement of $^{6}$He has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of $^{8}$He was determined with improved precision over our previous measurement. The obtained masses are $m$($^{6}$He) = 6.018 885 883(57) u and $m$($^{8}$He) = 8.033 934 44(11) u. The $^{6}$He value shows a deviation from the literature of 4$\sigma$. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) fm and 1.959(16) fm for $^{6}$He and $^{8}$He respectively. We present a detailed comparison to nuclear theory for $^6$He, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces.Comment: 4 pages, 2 figure

Differential immunity in pigs with high and low responses to porcine reproductive and respiratory syndrome virus infection

One hundred Hampshire × Duroc crossbred pigs (HD) and 100 NE Index line (I) pigs were infected with porcine reproductive and respiratory syndrome (PRRS) virus and evaluated for resistance/susceptibility. Controls (100/line) were uninfected littermates to the infected pigs. Viremia, change in weight (WTΔ), and rectal temperature at 0, 4, 7, and 14 d postinfection were recorded. Lung, bronchial lymph node (BLN), and blood tissue were collected at necropsy (14 d postinfection). The first principal component from principal component analyses of all variables was used to rank the pigs for phenotypic response to PRRS virus. Low responders (low PRRS burden) had high WTΔ, low viremia, and few lung lesions; high responders (high PRRS burden) had low WTΔ, high viremia, and many lesions. The RNA was extracted from lung and BLN tissue of the 7 highest and 7 lowest responders per line and from each of their littermates. Expression of 11 innate and T helper 1 immune markers was evaluated with cDNA in a 2 × 2 × 2 factorial design. Significant upregulation in lung, lymph, or both of infected pigs relative to controls occurred for all but one gene. Expression differences were greater in HD than I pigs. Significant downregulation for certain immune genes in low pigs, relative to littermate controls, was detected in lung and BLN, particularly in line I. Serum levels of the immune cytokines affirmed the gene expression differences. High preinfection serum levels of IL 8 were significantly associated with PRRS virus-resistant, low pigs. After infection, low expression of interferon gamma in cDNA and in serum was also correlated with PRRS virus resistance. Important genetic associations were revealed for fine mapping of candidate genes for PRRS virus resistance and determining the causative alleles

Trapped-ion decay spectroscopy towards the determination of ground-state components of double-beta decay matrix elements

A new technique has been developed at TRIUMF's TITAN facility to perform in-trap decay spectroscopy. The aim of this technique is to eventually measure weak electron capture branching ratios (ECBRs) and by this to consequently determine GT matrix elements of $\beta\beta$ decaying nuclei. These branching ratios provide important input to the theoretical description of these decays. The feasibility and power of the technique is demonstrated by measuring the ECBR of $^{124}$Cs.Comment: 9 pages, 9 figure

First Penning-trap mass measurement in the millisecond half-life range: the exotic halo nucleus 11Li

In this letter, we report a new mass for $^{11}$Li using the trapping experiment TITAN at TRIUMF's ISAC facility. This is by far the shortest-lived nuclide, $t_{1/2} = 8.8 \rm{ms}$, for which a mass measurement has ever been performed with a Penning trap. Combined with our mass measurements of $^{8,9}$Li we derive a new two-neutron separation energy of 369.15(65) keV: a factor of seven more precise than the best previous value. This new value is a critical ingredient for the determination of the halo charge radius from isotope-shift measurements. We also report results from state-of-the-art atomic-physics calculations using the new mass and extract a new charge radius for $^{11}$Li. This result is a remarkable confluence of nuclear and atomic physics.Comment: Formatted for submission to PR

Genetic Parameters and Effect of WUR Genotype on Piglet Response to Co-Infection with PRRS and PCV2b, with or without Vaccination for PRRS

Commercial crossbred nursery piglets were either vaccinated or not using a modified live porcine reproductive and respiratory syndrome (PRRS) virus vaccine and all pigs were co-infected with PRRS virus (PRRSV) and porcine circovirus type 2b (PCV2b) 28 days later. Genetic correlations indicate that traits associated with primary exposure to PRRSV infection (PRRS viral load (VL) of vaccinated pigs prior to co-infection and PRRS VL of non-vaccinated pigs post co-infection) are genetically the same trait. The WUR single nucleotide polymorphism on chromosome 4, previously associated with reduced PRRS VL under PRRSV-only infection, was associated with significantly reduced PRRS VL following vaccination and co-infection (for non-vaccinated pigs), but also with reduced PCV2b VL of vaccinated pigs. These results indicate a significant effect of WUR genotype on PRRS VL upon primary PRRS exposure, whether in a PRRSV-only or PRRS and PCV2b co-infected population, but also with PCV2b VL of vaccinated pigs under PRRS and PCV2b co- infection

Genetic parameters and genomic regions associated with piglet response to vaccination for porcine reproductive and respiratory syndrome (PRRS) virus and co-infection with PRRS virus and porcine circovirus type 2b (PCV2b)

Citation: Dunkelberger, J. R., Serao, N. V. L., Kerrigan, M. A., Lunney, J. K., Rowland, R. R. R., & Dekkers, J. C. M. (2016). Genetic parameters and genomic regions associated with piglet response to vaccination for porcine reproductive and respiratory syndrome (PRRS) virus and co-infection with PRRS virus and porcine circovirus type 2b (PCV2b). Journal of Animal Science, 94, 52-53. doi:10.2527/msasas2016-112Objectives of this research were to estimate genetic parameters and to identify genomic regions associated with PRRS viral load (VL), PCV2b VL, and average daily gain (ADG) in nursery pigs vaccinated or non-vaccinated for PRRS virus (PRRSV), followed by co-infection with PRRSV and PCV2b. Data used included 396 commercial crossbred pigs from two PRRS Host Genetics Consortium trials, all from the same genetic supplier. Pigs were sent to Kansas State University after weaning and randomly sorted into two rooms. All pigs in one room were vaccinated for PRRS, and 28 d later, pigs in both rooms were co-infected with PRRSV and PCV2b, followed for 42 d, and genotyped using the 80K BeadChip. PRRS VL after vaccination and post co-infection and PCV2b VL were calculated as area under the curve of serum viremia from ?28 to 0, 0 to 21, and 0 to 42 d post co-infection, respectively. Genetic parameters were estimated by fitting multivariate animal models in ASReml4 with litter and pen (trial) as additional random effects. Trait-specific fixed effects of trial and weight and age at vaccination were also fitted. Genome-wide association (GWA) studies were performed by fitting SNPs as fixed effects one at a time in bivariate animal models for the non-vaccinated (Non-Vx) and vaccinated (Vx) groups for each trait. Heritability estimates following vaccination were 0.31, 0.07, and 0.10 for ADG Non-Vx, ADG Vx, and PRRS Vx, respectively. During the co-infection period, heritability estimates were slightly higher at 0.53, 0.57, 0.56, 0.20, 0.18, and 0.15 for ADG Non-Vx, ADG Vx, PRRS Non-Vx, PRRS Vx, PCV2b Non-Vx, and PCV2b Vx, respectively. Standard errors ranged from 0.14 to 0.22. A strong, positive genetic correlation (0.95 ± 1.01) was observed for PRRS VL post-vaccination with PRRS VL Non-Vx. Unique genomic regions were identified between Vx and Non-Vx pigs for each trait, the most significant of which was identified for PCV2b VL and located near the major histocompatibility complex, an important region for response to infection. The chromosome 4 region, which has been associated with VL following PRRSV-only infection, was associated with PRRS VL Non-Vx but not PRRS Vx or PRRS VL post-vaccination. Together, these results suggest that selection for improved performance under co-infection of PRRS and PCV2b is possible. Additionally, identification of unique genomic regions between Vx and Non-Vx pigs may enable selection of pigs with better response to vaccination. This research was supported by USDA-NIFA grants 2012–38420–19286 and 2013–68004–20362

Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry

Ramsey's method of separated oscillatory fields is applied to the excitation of the cyclotron motion of short-lived ions in a Penning trap to improve the precision of their measured mass. The theoretical description of the extracted ion-cyclotron-resonance line shape is derived out and its correctness demonstrated experimentally by measuring the mass of the short-lived $^{38}$Ca nuclide with an uncertainty of $1.6\cdot 10^{-8}$ using the ISOLTRAP Penning trap mass spectrometer at CERN. The mass value of the superallowed beta-emitter $^{38}$Ca is an important contribution for testing the conserved-vector-current hypothesis of the electroweak interaction. It is shown that the Ramsey method applied to mass measurements yields a statistical uncertainty similar to that obtained by the conventional technique ten times faster.Comment: 5 pages, 4 figures, 0 table