Interpopulational variation in costs of reproduction related to pregnancy in a viviparous lizard

Interpopulational variation in reproductive costs may affect variation in life history traits including reproductive investment (i.e. clutch mass relative to either maternal body mass or length). While the relationships between reproductive investment and costs of reproduction, especially costs to mobility, have been well studied in squamate reptiles, how these costs relate to investment and explain patterns within and between populations is not always straightforward. In the present study, we examined the relationship between reproductive investment and costs of reproduction (gravid and postpartum sprint speeds and maternal postpartum body condition) in two populations of a viviparous skink, Pseudemoia entrecasteauxii living in different habitat types. We found that costs of reproduction (i.e. impact on gravid and postpartum sprint speeds) depended on the interaction between relative reproductive burden (RRB) and population. There was no link between relative clutch mass (RCM) and maternal sprint speeds. Maternal postpartum body condition was not related to either RRB or RCM for either population. Gravid females living in the open habitat population showed significantly slower sprint speed compared with the same females immediately postparturition, and other gravid females living in a closed habitat population. Such females are likely to experience a higher cost of reproduction in terms of changes in sprint speed as well as exposure to predators and may show a behavioural shift to crypsis in order to compensate for locomotor impairment and to reduce the risk of predation. We suggest that factors which relate to costs of reproduction (i.e. sprint speeds) are complex and may involve multiple factors such as reproductive investment and habitat characteristics

Kinetic energy sum spectra in nonmesonic weak decay of hypernuclei

We evaluate the coincidence spectra in the nonmesonic weak decay (NMWD) \Lambda N\go nN of $\Lambda$ hypernuclei $^{4}_\Lambda$He, $^{5}_\Lambda$He, $^{12}_\Lambda$C, $^{16}_\Lambda$O, and $^{28}_\Lambda$Si, as a function of the sum of kinetic energies $E_{nN}=E_n+E_N$ for $N=n,p$. The strangeness-changing transition potential is described by the one-meson-exchange model, with commonly used parameterization. Two versions of the Independent-Particle Shell Model (IPSM) are employed to account for the nuclear structure of the final residual nuclei. They are: (a) IPSM-a, where no correlation, except for the Pauli principle, is taken into account, and (b) IPSM-b, where the highly excited hole states are considered to be quasi-stationary and are described by Breit-Wigner distributions, whose widths are estimated from the experimental data. All $np$ and $nn$ spectra exhibit a series of peaks in the energy interval 110 MeV $<E_{nN}<170$ MeV, one for each occupied shell-model state. The IPSM-a could be a pretty fair approximation for the light $^{4}_\Lambda$He and $^{5}_\Lambda$He hypernuclei. For the remaining, heavier, hypernuclei it is very important, however, to take into account the spreading in strength of the deep-hole states, and bring into play the IPSM-b approach. Notwithstanding the nuclear model that is employed the results depend only very weakly on the details of the dynamics involved in the decay process proper. We propose that the IPSM is the appropriate lowest-order approximation for the theoretical calculations of the of kinetic energy sum spectra in the NMWD. It is in comparison to this picture that one should appraise the effects of the final state interactions and of the two-nucleon-induced decay mode.Comment: v1: 20 pages, 3 figures, 1 table, submitted for publication; v2: minor corrections, improved figures, published versio

The Memory Metal Minimal Access Cage: A New Concept in Lumbar Interbody Fusion—A Prospective, Noncomparative Study to Evaluate the Safety and Performance

Study Design/Objective. A single-centre, prospective, non-comparative study of 25 patients to evaluate the performance and safety of the Memory Metal Minimal Access Cage (MAC) in Lumbar Interbody Fusion. Summary of Background Data. Interbody fusion cages in general are designed to withstand high axial loads and in the meantime to allow ingrowth of new bone for bony fusion. In many cages the contact area with the endplate is rather large leaving a relatively small contact area for the bone graft with the adjacent host bone. MAC is constructed from the memory metal Nitinol and builds on the concept of sufficient axial support in combination with a large contact area of the graft facilitating bony ingrowth and ease in minimal access implantation due to its high deformability. Methods. Twenty five subjects with a primary diagnosis of disabling back and radicular leg pain from a single level degenerative lumbar disc underwent an interbody fusion using MAC and pedicle screws. Clinical performance was evaluated prospectively over 2 years using the Oswestry Disability Index (ODI), Short Form 36 questionnaire (SF-36) and pain visual analogue scale (VAS) scores. The interbody fusion status was assessed using conventional radiographs and CT scan. Safety of the device was studied by registration of intra- and post-operative adverse effects. Results. Clinical performance improved significantly (P < .0018), CT scan confirmed solid fusion in all 25 patients at two year follow-up. In two patients migration of the cage occurred, which was resolved uneventfully by placing a larger size at the subsequent revision. Conclusions. We conclude that the Memory Metal Minimal Access Cage (MAC) resulted in 100% solid fusions in 2 years and proved to be safe, although two patients required revision surgery in order to achieve solid fusion

Shedding some light on Thismia rodwayi F. Muell. (fairy lanterns) in Tasmania: distribution, habitat and conservation status

Thismia rodwayi is a seldom-seen, subterranean plant that occurs in Tasmania, the eastern states of the Australian mainland and New Zealand. Surveys for the species were prompted by a new record from Archers Sugarloaf near Meander in Tasmania's central north. Several new populations of the species were subsequently discovered in wet eucalypt forests dominated by Eucalyptus obliqua, E. regnans, E. delegatensis or E. viminalis, with an understorey dominated by Pomaderris apetala, Bedfordia salicina and/or Olearia argophylla. The species is now known from the Meander, Glen Huon, Little Denison River, Mount Field, Mount Wellington and Ben Lomond areas. Analysis of current information suggests that the listing of T. rodwayi under Schedule 5 (Rare) of the Tasmanian Threatened Species Protection Act 1995 is appropriate

Beta-gamma circular polarization correlation experiments

A circular polarization analyzer for γ rays is described. Measurements on circular polarization of bremsstrahlung due to β particles from P32 and Tm170 agree with previous and concurrent measurements and, together with Co60 circular polarization correlation studies, establish a check on the calculated calibration curve of the analyzer. We have studied the β-γ circular polarization correlation in the following allowed j-j transitions: Na24, Sc44, Sc46, V48, and Co58. The result for Sc46 indicates the presence of a strong interference between Gamow-Teller and Fermi couplings. The β interaction, therefore, should contain a combination of S and T, or (and) V and A, interactions with small or no phase difference between the interaction constants. If one assumes maximum interference, our experiments give information on the ratio of Gamow-Teller to Fermi interaction. The once-forbidden transition Au198 gives the maximum possible asymmetry. All results are in agreement with the 2-component neutrino theory and the assumption of V, A or alternatively S, T, P interaction

β-γ circular polarization correlation in a J-J transition

The study of β-γ circular polarization correlation in β transitions without spin change provides valuable information about β-decay coupling constants. (1,2) In particular, the experimental result will depend on the presence or absence of S,T and V,A interference terms.(2

Beta-gamma circular polarization correlation measurements

Owing to nonconservation of parity in β decay,(1) γ rays following β transitions are circularly polarized. The angular distribution of circularly polarized γ rays emitted under an angle 0 with the preceding β particles is W(0,±) = 1±A(v/c) cos0 (+ for right hand, - for left-hand circular polarization).(2

β-γ circular polarization correlation in Au198 and Co58

The β-γ circular polarization correlation provides a valuable tool for the study of the beta-decay interaction.(1,2) Recently a large interference term due to the presence of S and T or V and A interaction has been found in the allowed J-J transition of Sc46.(3) We report here studies of the J-J transitions in Au198 and Co58