The effect of cluster reconfiguration and non-stoichiometry on uranium vacancy migration in UO2

During reactor operation the release of fission gases from the fuel pellet is an important safety issue as it can lead to over-pressurization and failure of the fuel cladding. Uranium vacancy migration has been identified as the limiting step in the diffusion of fission gases through bulk UO2. The uranium vacancy migration energy is, therefore, an important parameter in this phenomenon, as well as other atomic scale processes, such as recovery from radiation damage. Chemical changes under taken by the fuel during irradiation lead to deviations from stoichiometric UO2 and the charge compensating defects that bind to the uranium vacancy also change. Therefore, we have examined the change in the migration energy for a uranium vacancy when bound to either two oxygen vacancies (Schottky defect) or to four U5+ cations (hole defects) representing UO2 and UO2+x respectively. By using empirical potentials within statics we were able to sample a large array of metastable cluster configurations to identify lower energy migration pathways that involve the reconfiguration of the cluster from the ground state configuration to metastable configurations (see UO2+x results in Figure 1). The work is published in ref [1]. Please click Additional Files below to see the full abstract

Bone metabolic responses to low energy availability achieved by diet or exercise in active eumenorrheic women

Purpose: We aimed to explore the effects of low energy availability (EA)[15 kcal·kg lean body mass (LBM)−1·d−1] achieved by diet or exercise on bone turnover markers in active, eumenorrheic women. Methods: By using a crossover design, ten eumenorrheic women (VO2 peak: 48.1 ± 3.3 ml·kg−1·min−1) completed all three, 3-day conditions in a randomised order: controlled EA (CON; 45 kcal·kgLBM−1·d−1), low EA through dietary energy restriction (D-RES; 15 kcal·kgLBM−1·d−1) and low EA through increasing exercise energy expenditure (E-RES; 15 kcal·kgLBM−1·d−1), during the follicular phase of three menstrual cycles. In CON, D-RES and E-RES, participants consumed diets providing 45, 15 and 45 kcal·kgLBM−1·d−1. In E-RES only, participants completed supervised running sessions (129 ± 10 min·d−1) at 70% of their VO2 peak that resulted in an exercise energy expenditure of 30 kcal·kg LBM−1·d−1. Blood samples were collected at baseline (BASE) and at the end of the 3-day period (D6) and analysed for bone turnover markers (β-CTX and P1NP), markers of calcium metabolism (PTH, albumin-adjusted Ca, Mg and PO4) and hormones (IGF-1, T3, insulin, leptin and 17β-oestradiol). Results: In D-RES, P1NP concentrations at D6 decreased by 17% (BASE: 54.8 ± 12.7 μg·L−1, D6: 45.2 ± 9.3 μg·L−1, P < 0.001, d = 0.91) and were lower than D6 concentrations in CON (D6: 52.5 ± 11.9 μg·L−1, P = 0.001). P1NP did not change significantly in E-RES (BASE: 55.3 ± 14.4 μg·L−1, D6: 50.9 ± 15.8 μg·L−1, P = 0.14). β-CTX concentrations did not change following D-RES (BASE: 0.48 ± 0.18 μg·L−1, D6: 0.55 ± 0.17 μg·L−1) or E-RES (BASE: 0.47 ± 0.24 μg·L−1, D6: 0.49 ± 0.18 μg·L−1) (condition × time interaction effect, P = 0.17). There were no significant differences in P1NP (P = 0.25) or β-CTX (P = 0.13) responses between D-RES and E-RES. Both conditions resulted in reductions in IGF-1 (−13% and − 23% from BASE in D-RES and E-RES, both P < 0.01) and leptin (−59% and − 61% from BASE in D-RES and E-RES, both P < 0.001); T3 decreased in D-RES only (−15% from BASE, P = 0.002) and PO4 concentrations decreased in E-RES only (−9%, P = 0.03). Conclusions: Low EA achieved through dietary energy restriction resulted in a significant decrease in bone formation but no change in bone resorption, whereas low EA achieved through exercise energy expenditure did not significantly influence bone metabolism. Both low EA conditions elicited significant and similar changes in hormone concentrations

Stability of Scalar Fields in Warped Extra Dimensions

This work sets up a general theoretical framework to study stability of models with a warped extra dimension where N scalar fields couple minimally to gravity. Our analysis encompasses Randall-Sundrum models with branes and bulk scalars, and general domain-wall models. We derive the Schrodinger equation governing the spin-0 spectrum of perturbations of such a system. This result is specialized to potentials generated using fake supergravity, and we show that models without branes are free of tachyonic modes. Turning to the existence of zero modes, we prove a criterion which relates the number of normalizable zero modes to the parities of the scalar fields. Constructions with definite parity and only odd scalars are shown to be free of zero modes and are hence perturbatively stable. We give two explicit examples of domain-wall models with a soft wall, one which admits a zero mode and one which does not. The latter is an example of a model that stabilizes a compact extra dimension using only bulk scalars and does not require dynamical branes.Comment: 25 pages, 2 figures; v2: minor changes to text, references added, matches published versio

Bone metabolic marker concentrations across the menstrual cycle and phases of combined oral contraceptive use

There is a need to further understand the impact of the menstrual cycle and phase of combined oral contraceptive (COC) use on the pre-analytical variability of markers of bone metabolism in order to improve standardisation procedures for clinical practice and research. The aim of this study was to assess bone metabolism marker concentrations across the menstrual cycle and phases of COC use. Carboxy-terminal cross-linking telopeptide of type I collagen (β-CTX), procollagen type 1 N propeptide (P1NP) and Bone alkaline phosphatase (Bone ALP) concentrations were assessed in eumenorrheic women (n = 14) during the early follicular, ovulatory and mid-luteal phases of the menstrual cycle and in COC (Microgynon®) (n = 14) users on day 2-3 of pill consumption (PC1), day 15-16 pill consumption (PC2) and day 3-4 of the pill free interval (PFI). β-CTX was significantly (-16%) lower at PC2 compared to PC1 (P = 0.015) in COC users and was not affected by menstrual cycle phase (P > 0.05). P1NP and Bone ALP were not significantly different across either menstrual cycle phase or phase of COC use (all P > 0.05). There was no difference in pooled bone marker concentrations between eumenorrheic women and COC users (P > 0.05). In contrast to some previous studies, this study showed that bone marker concentrations do not significantly fluctuate across the menstrual cycle. Furthermore, bone resorption markers are significantly affected by phase of COC use, although bone formation markers do not significantly vary by COC phase. Therefore, the phase of COC use should be considered in clinical practice and research when assessing markers of bone metabolism as this can impact circulating concentrations of bone metabolic markers yet is not currently considered in existing guidelines for best practice

Neonatal local noxious insult affects gene expression in the spinal dorsal horn of adult rats

Neonatal noxious insult produces a long-term effect on pain processing in adults. Rats subjected to carrageenan (CAR) injection in one hindpaw within the sensitive period develop bilateral hypoalgesia as adults. In the same rats, inflammation of the hindpaw, which was the site of the neonatal injury, induces a localized enhanced hyperalgesia limited to this paw. To gain an insight into the long-term molecular changes involved in the above-described long-term nociceptive effects of neonatal noxious insult at the spinal level, we performed DNA microarray analysis (using microarrays containing oligo-probes for 205 genes encoding receptors and transporters for glutamate, GABA, and amine neurotransmitters, precursors and receptors for neuropeptides, and neurotrophins, cytokines and their receptors) to compare gene expression profiles in the lumbar spinal dorsal horn (LDH) of adult (P60) male rats that received neonatal CAR treatment within (at postnatal day 3; P3) and outside (at postnatal 12; P12) of the sensitive period. The data were obtained both without inflammation (at baseline) and during complete Freund's adjuvant induced inflammation of the neonatally injured paw. The observed changes were verified by real-time RT-PCR. This study revealed significant basal and inflammation-associated aberrations in the expression of multiple genes in the LDH of adult animals receiving CAR injection at P3 as compared to their expression levels in the LDH of animals receiving either no injections or CAR injection at P12. In particular, at baseline, twelve genes (representing GABA, serotonin, adenosine, neuropeptide Y, cholecystokinin, opioid, tachykinin and interleukin systems) were up-regulated in the bilateral LDH of the former animals. The baseline condition in these animals was also characterized by up-regulation of seven genes (encoding members of GABA, cholecystokinin, histamine, serotonin, and neurotensin systems) in the LDH ipsilateral to the neonatally-injured paw. The largest aberration in gene expression, however, was observed during inflammation of the neonatally injured hindpaws in the ipsilateral LDH, which included thirty-six genes (encoding numerous members of glutamate, serotonin, GABA, calcitonin gene-related peptide, neurotrophin, and interleukin systems). These findings suggest that changes in gene expression may be involved in the long-term nociceptive effects of neonatal noxious insult at the spinal level

An allocation Malmquist index with an application in the China securities industry

This paper proposes an allocation Malmquist index which is inspired by the work on the non-parametric cost Malmquist index. We first show that how to decompose the cost Malmquist index into the input-oriented Malmquist index and the allocation Malmquist index. An application in corporate management of the China securities industry with the panel data set of 40 securities companies during the period 2005–2011 shows the practicality of the propose model

Super-A-polynomials for Twist Knots

We conjecture formulae of the colored superpolynomials for a class of twist knots $K_p$ where p denotes the number of full twists. The validity of the formulae is checked by applying differentials and taking special limits. Using the formulae, we compute both the classical and quantum super-A-polynomial for the twist knots with small values of p. The results support the categorified versions of the generalized volume conjecture and the quantum volume conjecture. Furthermore, we obtain the evidence that the Q-deformed A-polynomials can be identified with the augmentation polynomials of knot contact homology in the case of the twist knots.Comment: 22+16 pages, 16 tables and 5 figures; with a Maple program by Xinyu Sun and a Mathematica notebook in the ancillary files linked on the right; v2 change in appendix B, typos corrected and references added; v3 change in section 3.3; v4 corrections in Ooguri-Vafa polynomials and quantum super-A-polynomials for 7_2 and 8_1 are adde

Remarkable Rates of Lightning Strike Mortality in Malawi

Livingstone's second mission site on the shore of Lake Malawi suffers very high rates of consequential lightning strikes. Comprehensive interviewing of victims and their relatives in seven Traditional Authorities in Nkhata Bay District, Malawi revealed that the annual rate of consequential strikes was 419/million, more than six times higher than that in other developing countries; the rate of deaths from lightning was 84/million/year, 5.4 times greater than the highest ever recorded. These remarkable figures reveal that lightning constitutes a significant stochastic source of mortality with potential life history consequences, but it should not deflect attention away from the more prominent causes of mortality in this rural area