The impact of low-mode symmetry on inertial fusion energy output in the burning plasma state

Indirect Drive Inertial Confinement Fusion Experiments on the National Ignition Facility (NIF) have achieved a burning plasma state with neutron yields exceeding 170 kJ, roughly 3 times the prior record and a necessary stage for igniting plasmas. The results are achieved despite multiple sources of degradations that lead to high variability in performance. Results shown here, for the first time, include an empirical correction factor for mode-2 asymmetry in the burning plasma regime in addition to previously determined corrections for radiative mix and mode-1. Analysis shows that including these three corrections alone accounts for the measured fusion performance variability in the two highest performing experimental campaigns on the NIF to within error. Here we quantify the performance sensitivity to mode-2 symmetry in the burning plasma regime and apply the results, in the form of an empirical correction to a 1D performance model. Furthermore, we find the sensitivity to mode-2 determined through a series of integrated 2D radiation hydrodynamic simulations to be consistent with the experimentally determined sensitivity only when including alpha-heating.

Design of the first fusion experiment to achieve target energy gain G>1

In this work we present the design of the first controlled fusion laboratory experiment to reach target gain G>1 N221204 (5 December 2022) [Phys. Rev. Lett. 132, 065102 (2024)10.1103/PhysRevLett.132.065102], performed at the National Ignition Facility, where the fusion energy produced (3.15 MJ) exceeded the amount of laser energy required to drive the target (2.05 MJ). Following the demonstration of ignition according to the Lawson criterion N210808, experiments were impacted by nonideal experimental fielding conditions, such as increased (known) target defects that seeded hydrodynamic instabilities or unintentional low-mode asymmetries from nonuniformities in the target or laser delivery, which led to reduced fusion yields less than 1 MJ. This Letter details design changes, including using an extended higher-energy laser pulse to drive a thicker high-density carbon (also known as diamond) capsule, that led to increased fusion energy output compared to N210808 as well as improved robustness for achieving high fusion energies (greater than 1 MJ) in the presence of significant low-mode asymmetries. For this design, the burnup fraction of the deuterium and tritium (DT) fuel was increased (approximately 4% fuel burnup and a target gain of approximately 1.5 compared to approximately 2% fuel burnup and target gain approximately 0.7 for N210808) as a result of increased total (DT plus capsule) areal density at maximum compression compared to N210808. Radiation-hydrodynamic simulations of this design predicted achieving target gain greater than 1 and also the magnitude of increase in fusion energy produced compared to N210808. The plasma conditions and hotspot power balance (fusion power produced vs input power and power losses) using these simulations are presented. Since the drafting of this manuscript, the results of this paper have been replicated and exceeded (N230729) in this design, together with a higher-quality diamond capsule, setting a new record of approximately 3.88MJ of fusion energy and fusion energy target gain of approximately 1.9.

Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health?

Several rare genetic variations of human XDH have been shown to alter xanthine oxidoreductase (XOR) activity leading to impaired purine catabolism. However, XOR is a multi-functional enzyme that depending upon the environmental conditions also expresses oxidase activity leading to both O2·- and H2O2 and nitrite (NO2-) reductase activity leading to nitric oxide (·NO). Since these products express important, and often diametrically opposite, biological activity, consideration of the impact of XOR mutations in the context of each aspect of the biochemical activity of the enzyme is needed to determine the potential full impact of these variants. Herein, we show that known naturally occurring hXDH mutations do not have a uniform impact upon the biochemical activity of the enzyme in terms of uric acid (UA), reactive oxygen species (ROS) and nitric oxide ·NO formation. We show that the His1221Arg mutant, in the presence of xanthine, increases UA, O2·- and NO generation compared to the WT, whilst the Ile703Val increases UA and ·NO formation, but not O2·-. We speculate that this change in the balance of activity of the enzyme is likely to endow those carrying these mutations with a harmful or protective influence over health that may explain the current equipoise underlying the perceived importance of XDH mutations. We also show that, in presence of inorganic NO2-, XOR-driven O2·- production is substantially reduced. We suggest that targeting enzyme activity to enhance the NO2--reductase profile in those carrying such mutations may provide novel therapeutic options, particularly in cardiovascular disease.

Memory of social experience affects female fecundity via perception of fly deposits

Background

Animals can exhibit remarkable reproductive plasticity in response  to their social surroundings, with profound fitness consequences. The presence of same-sex conspecifics can signal current or future expected competition for resources or mates. Plastic responses to elevated sexual competition caused by exposure to same-sex individuals have been well-studied in males. However, much less is known about such plastic responses in females, whether this represents sexual or resource competition, or if it leads to changes in investment in mating behaviour and/or reproduction. Here, we used Drosophila melanogaster to measure the impact of experimentally varying female exposure to other females prior to mating on fecundity before and after mating. We then deployed physical and genetic methods to manipulate the perception of different social cues and sensory pathways and reveal the potential mechanisms involved.

Results

The results showed that females maintained in social isolation prior to mating were significantly more likely to retain unfertilised eggs before mating, but to show the opposite and lay significantly more fertilised eggs in the 24h after mating. More than 48h of exposure to other females was necessary for this social memory response to be expressed. Neither olfactory nor visual cues were involved in mediating fecundity plasticity—instead, the relevant cues were perceived through direct contact with the non-egg deposits left behind by other females.

Conclusions

The results demonstrate that females show reproductive plasticity in response to their social surroundings and can carry this memory of their social experience forward through mating. Comparisons of our results with previous work show that the nature of female plastic reproductive responses and the cues they use differ markedly from those of males. The results emphasise the deep divergence in how each sex realises its reproductive success.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01438-5.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Slow and Fast Light in Plasma Using Optical Wave Mixing

Slow and fast light, or large changes in the group velocity of light, have been observed in a range of optical media, but the fine optical control necessary to induce an observable effect has not been achieved in a plasma. Here, we describe how the ion-acoustic response in a fully ionized plasma can produce large and measurable changes in the group velocity of light. We show the first experimental demonstration of slow and fast light in a plasma, measuring group velocities between 0.12c and -0.34c.

Genomic sequence analysis reveals diversity of Australian Xanthomonas species associated with bacterial leaf spot of tomato, capsicum and chilli

Background

The genetic diversity in Australian populations of Xanthomonas species associated with bacterial leaf spot in tomato, capsicum and chilli were compared to worldwide bacterial populations. The aim of this study was to confirm the identities of these Australian Xanthomonas species and classify them in comparison to overseas isolates. Analysis of whole genome sequence allows for the investigation of bacterial population structure, pathogenicity and gene exchange, resulting in better management strategies and biosecurity.

Results

Phylogenetic analysis of the core genome alignments and SNP data grouped strains in distinct clades. Patterns observed in average nucleotide identity, pan genome structure, effector and carbohydrate active enzyme profiles reflected the whole genome phylogeny and highlight taxonomic issues in X. perforans and X. euvesicatoria. Circular sequences with similarity to previously characterised plasmids were identified, and plasmids of similar sizes were isolated. Potential false positive and false negative plasmid assemblies were discussed. Effector patterns that may influence virulence on host plant species were analysed in pathogenic and non-pathogenic xanthomonads.

Conclusions

The phylogeny presented here confirmed X. vesicatoria, X. arboricola, X. euvesicatoria and X. perforans and a clade of an uncharacterised Xanthomonas species shown to be genetically distinct from all other strains of this study. The taxonomic status of X. perforans and X. euvesicatoria as one species is discussed in relation to whole genome phylogeny and phenotypic traits. The patterns evident in enzyme and plasmid profiles indicate worldwide exchange of genetic material with the potential to introduce new virulence elements into local bacterial populations.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5600-x) contains supplementary material, which is available to authorized users.

Theory and measurements of convective Raman side scatter in inertial confinement fusion experiments

Raman side scatter, whereby scattered light is resonant while propagating perpendicularly to a density gradient in a plasma, was identified experimentally in planar-target experiments at the National Ignition Facility at intensities orders of magnitudes below the threshold for absolute instability. We have derived a new theoretical description of convective Raman side scatter below the absolute threshold, validated by numerical simulations. We show that inertial confinement fusion experiments at full ignition scale, i.e., with mm-scale spot sizes and density scale lengths, are prone to increased coupling losses from Raman side scatter as the instability can extend from the absolute regime near the quarter-critical density to the convective regime at lower electron densities.

Origins and Scaling of Hot-Electron Preheat in Ignition-Scale Direct-Drive Inertial Confinement Fusion Experiments

Planar laser-plasma interaction (LPI) experiments at the National Ignition Facility (NIF) have allowed access for the first time to regimes of electron density scale length (∼500 to 700  μm), electron temperature (∼3 to 5 keV), and laser intensity (6 to 16×10^{14}  W/cm^{2}) that are relevant to direct-drive inertial confinement fusion ignition. Unlike in shorter-scale-length plasmas on OMEGA, scattered-light data on the NIF show that the near-quarter-critical LPI physics is dominated by stimulated Raman scattering (SRS) rather than by two-plasmon decay (TPD). This difference in regime is explained based on absolute SRS and TPD threshold considerations. SRS sidescatter tangential to density contours and other SRS mechanisms are observed. The fraction of laser energy converted to hot electrons is ∼0.7% to 2.9%, consistent with observed levels of SRS. The intensity threshold for hot-electron production is assessed, and the use of a Si ablator slightly increases this threshold from ∼4×10^{14} to ∼6×10^{14}  W/cm^{2}. These results have significant implications for mitigation of LPI hot-electron preheat in direct-drive ignition designs.

Longitudinal and Transverse Instability of Ion Acoustic Waves

Ion acoustic waves are found to be susceptible to at least two distinct decay processes. Which process dominates depends on the parameters. In the cases examined, the decay channel where daughter modes propagate parallel to the mother mode is found to dominate at larger amplitudes, while the decay channel where the daughter modes propagate at angles to the mother mode dominates at smaller amplitudes. Both decay processes may occur simultaneously and with onset thresholds below those suggested by fluid theory, resulting in the eventual multidimensional collapse of the mother mode to a turbulent state.

Variation in the post-mating fitness landscape in fruit flies

Sperm competition is pervasive and fundamental to determining a male's overall fitness. Sperm traits and seminal fluid proteins (Sfps) are key factors. However, studies of sperm competition may often exclude females that fail to remate during a defined period. Hence, the resulting data sets contain fewer data from the potentially fittest males that have most success in preventing female remating. It is also important to consider a male's reproductive success before entering sperm competition, which is a major contributor to fitness. The exclusion of these data can both hinder our understanding of the complete fitness landscapes of competing males and lessen our ability to assess the contribution of different determinants of reproductive success to male fitness. We addressed this here, using the Drosophila melanogaster model system, by (i) capturing a comprehensive range of intermating intervals that define the fitness of interacting wild-type males and (ii) analysing outcomes of sperm competition using selection analyses. We conducted additional tests using males lacking the sex peptide (SP) ejaculate component vs. genetically matched (SP+ ) controls. This allowed us to assess the comprehensive fitness effects of this important Sfp on sperm competition. The results showed a signature of positive, linear selection in wild-type and SP+ control males on the length of the intermating interval and on male sperm competition defence. However, the fitness surface for males lacking SP was distinct, with local fitness peaks depending on contrasting combinations of remating intervals and offspring numbers. The results suggest that there are alternative routes to success in sperm competition and provide an explanation for the maintenance of variation in sperm competition traits.

Resource limitation and responses to rivals in males of the fruit fly Drosophila melanogaster

Diet has a profound direct and indirect effect on reproductive success in both sexes. Variation in diet quality and quantity can significantly alter the capacity of females to lay eggs and of males to deliver courtship. Here, we tested the effect of dietary resource limitation on the ability of male Drosophila melanogaster to respond adaptively to rivals by extending their mating duration. Previous work carried out under ad libitum diet conditions showed that males exposed to rivals prior to mating significantly extend mating duration, transfer more ejaculate proteins and achieve higher reproductive success. Such adaptive responses are predicted to occur because male ejaculate production may be limited. Hence, ejaculate resources require allocation across different reproductive bouts, to balance current vs. future reproductive success. However, when males suffer dietary limitation, and potentially have fewer reproductive resources to apportion, we expect adaptive allocation of responses to rivals to be minimized. We tested this prediction and found that males held on agar‐only diets for 5–7 days lost the ability to extend mating following exposure to rivals. Interestingly, extended mating was retained in males held on low yeast/sugar: no sugar/yeast diet treatments, but was mostly lost when males were maintained on ‘imbalanced’ diets in which there was high yeast: no sugar and vice versa. Overall, the results show that males exhibit adaptive responses to rivals according to the degree of dietary resource limitation and to the ratio of individual diet components.

High Power Dynamic Polarization Control Using Plasma Photonics

We report the first experimental demonstration of a plasma wave plate based on laser-induced birefringence. An elliptically polarized input was converted into a nearly ideal circularly polarized beam using an optical system composed of a second laser beam and a plasma. The results are in excellent agreement with linear theory and three-dimensional simulations up to phase delays exceeding π/4, thus establishing the feasibility of laser-plasma photonic devices that are ultrafast, damage-resistant, and easily tunable.

Microguards and micromessengers of the genome

The regulation of gene expression is of fundamental importance to maintain organismal function and integrity and requires a multifaceted and highly ordered sequence of events. The cyclic nature of gene expression is known as 'transcription dynamics'. Disruption or perturbation of these dynamics can result in significant fitness costs arising from genome instability, accelerated ageing and disease. We review recent research that supports the idea that an important new role for small RNAs, particularly microRNAs (miRNAs), is in protecting the genome against short-term transcriptional fluctuations, in a process we term 'microguarding'. An additional emerging role for miRNAs is as 'micromessengers'-through alteration of gene expression in target cells to which they are trafficked within microvesicles. We describe the scant but emerging evidence that miRNAs can be moved between different cells, individuals and even species, to exert biologically significant responses. With these two new roles, miRNAs have the potential to protect against deleterious gene expression variation from perturbation and to themselves perturb the expression of genes in target cells. These interactions between cells will frequently be subject to conflicts of interest when they occur between unrelated cells that lack a coincidence of fitness interests. Hence, there is the potential for miRNAs to represent both a means to resolve conflicts of interest, as well as instigate them. We conclude by exploring this conflict hypothesis, by describing some of the initial evidence consistent with it and proposing new ideas for future research into this exciting topic.

Beyond the gain exponent: Effect of damping, scale length, and speckle length on stimulated scatter

Three-dimensional wave propagation simulations and experiments show that the gain exponent, an often used metric to assess the likelihood of stimulated Brillouin scatter, is insufficient and must be augmented with another parameter, Nr, the ratio of the resonance length, Lres, to the laser speckle length. The damping rate of ion acoustic waves, ν, and thus Lres, which is proportional to ν, are easily varied with plasma species composition, e.g., by varying the ratio of hydrogen and carbon ions. As Nr decreases, stimulated Brillouin scattering increases despite the same gain exponent.

Kinetic simulations of the self-focusing and dissipation of finite-width electron plasma waves

Two-dimensional simulations, both Vlasov and particle-in-cell, are presented that show the evolution of the field and electron distribution of finite-width, nonlinear electron plasma waves. The intrinsically intertwined effects of self-focusing and dissipation of field energy caused by electron trapping are studied in simulated systems that are hundreds of wavelengths long in the transverse direction but only one wavelength long and periodic in the propagation direction. From various initial wave states, both the width at focus Δm relative to the initial width Δ0 and the maximum field amplitude at focus are shown to be a function of the growth rate of the transverse modulational instability γTPMI divided by the loss rate of field energy νE to electrons escaping the trapping region. With dissipation included, an amplitude threshold for self-focusing γTPMI/νE∼1 is found that supports the analysis of Rose [Phys. Plasmas 12, 012318 (2005)].

Kinetic theory and Vlasov simulation of nonlinear ion-acoustic waves in multi-ion species plasmas

The theory of damping and nonlinear frequency shifts from particles resonant with ion-acoustic waves (IAWs) is presented for multi-ion species plasma and compared to driven wave Vlasov simulations. Two distinct IAW modes may be supported in multi-ion species plasmas, broadly classified as fast and slow by their phase velocity relative to the constituent ion thermal velocities. In current fusion-relevant long pulse experiments, the ion to electron temperature ratio, T(i)/T(e), is expected to reach a level such that the least damped and thus more readily driven mode is the slow mode, with both linear and nonlinear properties that are shown to differ significantly from the fast mode. The lighter ion species of the slow mode is found to make no significant contribution to the IAW frequency shift despite typically being the dominant contributor to the Landau damping.

Spray-dried porcine plasma and yeast derived protein meal influence the adaption to weaning of primiparous and multiparous sow progeny in different ways

Pigs from 154 litters (n = 1132, 19 ± 3 days of age, 4.9 ± 1.1 kg of bodyweight) were used in a 3 × 2 factorial design to evaluate two raw materials with nutraceutical properties being used in feeds, spray-dried porcine plasma (SDPP) and a yeast protein meal, and their effects on growth performance, immune parameters and gastrointestinal adaption of piglets to weaning. Factors included dietary treatments being (1) 5% SDPP (PLA), (2) 3.5% yeast protein meal (NUP) and (3) medicated control (TMC) and parity (primiparous versus multiparous). The treatment groups were imposed from Day 19 through to weaning at Day 27. Selected pigs (n = 720, 28 ± 3 days of age, 7.4 ± 1.0 kg of bodyweight) were weaned and remained on their respective diets from Day 28 to Day 34. From Day 35 to Day 48 all group-housed pigs were offered a commercial weaner 1 diet, and from Day 49 to Day 68 pigs were offered a commercial weaner 2 diet. Growth performance, survival, and serum immunoglobulin G were monitored throughout the nursery phase (Day 28 to Day 68). Adaptation of the gastrointestinal tract in the acute post-weaning phase (Day 28 to Day 34) was assessed in 36 individually housed male weaners, with the effects of feed on structural, digestive, microbial and immune parameters along the gastrointestinal tract determined at Day 34. Pre-weaning feed disappearance was greater (P < 0.01) in multiparous litters independent of diet. In the commercial nursery, total removals (mortality and morbidity) were highest (P < 0.01) in primiparous sow progeny, with pigs offered NUP having greater (P ≤ 0.05) total removals. Pigs offered PLA had superior average daily gain, average daily feed intake and feed conversion ratio from Day 28 to Day 34 (P < 0.05). Pigs offered NUP tended to (P = 0.07) have superior average daily gain from Day 35 to Day 49. Pigs offered NUP had higher (P < 0.05) serum immunoglobulin G concentrations at Day 68 compared with pigs offered TMC, with the effect most pronounced in primiparous sow progeny. Individually housed weaners offered PLA consumed more (P < 0.05) feed on Day 30 to Day 31, had shorter relative intestine length (P < 0.05), greater villous height in the medial jejunum (P < 0.10) and lower immuno-pathology scores along the intestine. Pigs offered PLA also tended (P < 0.10) to have increased pancreatic-specific lipase and amylase activity compared with pigs offered NUP. Pigs offered NUP had a higher ratio of E. coli : coliforms in the colon (P < 0.01) and more counts of β-haemolytic bacteria in the medial jejunum (P < 0.05) and colon (P < 0.10). Diets containing either SDPP or NUP offered pigs benefits beyond nutrition relative to the medicated control diet. The benefits of SDPP were highly effective but transient, while the yeast derived protein had a successive or accumulative effect which was more pronounced in primiparous sow progeny.

Sex peptide of Drosophila melanogaster males is a global regulator of reproductive processes in females

Seminal fluid proteins (Sfps) alter female behaviour and physiology and can mediate sexual conflict. In Drosophila melanogaster, a single Sfp, the sex peptide (SP), triggers remarkable post-mating responses in females, including altered fecundity, feeding, immunity and sexual receptivity. These effects can favour the evolutionary interests of males while generating costs in females. We tested the hypothesis that SP is an upstream master-regulator able to induce diverse phenotypes through efficient induction of widespread transcriptional changes in females. We profiled mRNA responses to SP in adult female abdomen (Abd) and head+thorax (HT) tissues using microarrays at 3 and 6 h following mating. SP elicited a rich, subtle signature of temporally and spatially controlled mRNAs. There were significant alterations to genes linked to egg development, early embryogenesis, immunity, nutrient sensing, behaviour and, unexpectedly, phototransduction. There was substantially more variation in the direction of differential expression across time points in the HT versus Abd. The results support the idea that SP is an important regulator of gene expression in females. The expression of many genes in one sex can therefore be under the influence of a regulator expressed in the other. This could influence the extent of sexual conflict both within and between loci.

Variation in adult sex ratio alters the association between courtship, mating frequency and paternity in the lek-forming fruitfly Ceratitis capitata

The intensity with which males deliver courtship and the frequency with which they mate are key components of male reproductive success. However, we expect the strength of the relationship between these traits and a male's overall paternity to be strongly context dependent, for example to be altered significantly by the extent of post-mating competition. We tested this prediction in a lekking insect, Ceratitis capitata (medfly). We examined the effect of manipulating the sex ratio from male- to female-biased (high and low male competition, respectively) on courtship behaviour, mating frequency and paternity of focal males. Under high male competition, focal males delivered significantly more courtship but gained lower paternity than under lower competition. Paternity was positively associated with mating frequency and small residual testes size. However, the association between mating frequency and paternity was significantly stronger under low competition. We conclude that manipulation of sex ratio significantly altered the predictors of mating success and paternity. The relationship between pre- and post-mating success is therefore plastic and alters according to the prevailing level of competition. The results highlight the importance of post-copulatory processes in lekking species and illuminate selection pressures placed on insects such as medflies that are mass reared for pest control.

Driven spatially autoresonant stimulated Raman scattering in the kinetic regime

The autoresonant behavior of Langmuir waves excited by stimulated Raman scattering (SRS) is clearly identified in particle-in-cell (PIC) simulations in an inhomogeneous plasma. As previously shown via a 3-wave coupling model [T. Chapman et al., Phys. Plasmas 17, 122317 (2010)], weakly kinetic effects such as trapping can be described via an amplitude-dependent frequency shift that compensates the dephasing of the resonance of SRS due to the inhomogeneity. The autoresonance (AR) leads to phase locking and to growth of the Langmuir wave beyond the spatial amplification expected from Rosenbluth's model in an inhomogeneous profile [M. N. Rosenbluth, Phys. Rev. Lett. 29, 565 (1972)]. Results from PIC simulations and from a 3-wave coupling code show very good agreement, leading to the conclusion that AR arises even beyond the so-called weakly kinetic regime.

Characterisation of amyloid-induced inflammatory responses in the rat retina

Amyloid-induced inflammation is thought to play a critical and early role in the pathophysiology of Alzheimer's disease. As such, robust models with relevant and accessible compartments that provide a means of assessing anti-inflammatory agents are essential for the development of therapeutic agents. In the present work, we have characterised the induction of inflammation in the rat retina following intravitreal administration of amyloid-beta protein (Aβ). Histology and mRNA endpoints in the retina demonstrate Aβ1-42-, but not Aβ42-1-, induced inflammatory responses characterised by increases in markers for microglia and astrocytes (ionised calcium-binding adaptor molecule 1 (iba-1), GFAP and nestin) and increases in mRNA for inflammatory cytokines and chemokines such as IL1-β, MIP1α and TNFα. Likewise, analysis of vitreal cytokines also revealed increases in inflammatory cytokines and chemokines, including IL1-β, MIP1α and MCP1, induced by Aβ1-42 but not Aβ42-1. This profile of pro-inflammatory gene and protein expression is consistent with that observed in the Alzheimer's disease brain and suggest that this preclinical model may provide a useful relevant tool in the development of anti-inflammatory approaches directed towards Alzheimer's disease therapy.

Female nutritional status determines the magnitude and sign of responses to a male ejaculate signal in Drosophila melanogaster

Ejaculate chemicals transferred from males to females during mating cause significant changes in female behaviour and physiology, but the causes of phenotypic variation in these responses is little understood. We tested here the effect of adult female nutrition on the response of female Drosophila melanogaster to a specific ejaculate component, the sex peptide (SP), which is of interest because of its effects on female egg laying, sexual receptivity, feeding rate, immune responses and potential role in mediating sexual conflict. We exposed adult females to five different diets and kept them continuously with males that did or did not transfer SP. Diet altered the presence, magnitude and sign of the effects of SP on different phenotypic traits (egg laying, receptivity and lifespan) and different traits responded in different ways. This showed that the set of responses to mating can be uncoupled and can vary independently in different environments. Importantly, diet also significantly affected whether exposure to SP transferring males was beneficial or costly to females, with beneficial effects occurring more often than expected. Hence, the food environment can also shape significantly the strength and direction of selection on mating responses.

Decreased muscle strength following management of breast cancer

PURPOSE

To assess whether muscle strength, power and endurance at the affected shoulder were reduced in women treated for breast cancer. Secondly, we assessed whether muscle performance was explained by management or other symptoms.

METHODS

Participants were 40 women (mean +/- SD: 56.7 +/- 11.6 yr) who had completed all treatments for breast cancer at least 6 m previously. We measured dynamic concentric strength at one repetition maximum (1RM), endurance at 90% 1RM, and power through a range of 40-100% 1RM for shoulder protractors, extensors and retractors. Strength and endurance, but not power, were measured for shoulder flexors. Additionally, maximal grip strength, passive shoulder range of motion and arm circumference were measured. Self-reported symptoms were recorded using a questionnaire.

RESULTS

Shoulder protractors (p = 0.011), retractors (p = 0.007), and extensors (p = 0.009), but not flexors, were significantly weaker on the affected side compared to the unaffected side. Muscle power and endurance at the shoulder and grip strength were not impaired. Inter-limb differences in muscle strength were not explained by the surgical and medical management of the cancer. Self-reported weakness correlated poorly with our measures of muscle strength.

CONCLUSIONS

Long-term weakness occurs about the shoulder secondary to treatment for breast cancer. Strategies to prevent weakness need to be considered.

Sexual conflict and reproductive isolation in flies

Sexual conflict is predicted to generate more rapid reproductive isolation between larger populations. While there is some empirical support for this, the data are inconsistent and, additionally, there has been criticism of some of the evidence. Here we reanalyse two experimental-evolution datasets using an isolation index widely applied in the speciation literature. We find evidence for reproductive isolation through sexual conflict in Sepsis cynipsea, but not in Drosophila melanogaster, and this occurred to a greater degree in larger populations, which is consistent with previous findings.

Monitoring the role of aceticlasts in anaerobic digestion: activity and capacity

Aceticlastic methanogens are seen as a key to digester capacity and stability. This paper develops and applies an assay to measure digester stability by measuring the maximum aceticlastic methane production rate (Vmax,ac). The Vmax,ac in combination with acetate concentrations was found to be an effective digestion monitoring tool to indicate process upsets. At steady state, thermophilic, first stage and short SRT digesters generally had a greater Vmax,ac than mesophilic, second stage or long SRT digesters. The ratio of the Vmax,ac to the plant aceticlastic methane production rate, termed the Acetate Capacity Number (ACN), is a measure of the excess capacity of the digester. Either Vmax,ac or ACN can be used to estimate the capability to handle higher organic loading rates. Monod modeling was used to predict Vmax,ac, ACN and maximum VS loading rates for mesophilic and thermophilic digestion and for staged digesters to better understand expected digestion capacity and stability.

The benefits of male ejaculate sex peptide transfer in Drosophila melanogaster

The accessory gland protein (Acp) ejaculate molecules of male Drosophila melanogaster mediate sexual selection and sexual conflict at the molecular level. However, to date no studies have comprehensively measured the timing and magnitude of fitness benefits to males of transferring specific Acps. This is an important omission because without this information it is not possible to fully understand the strength and form of selection acting on adaptations such as Acps. Here, we measured the fitness benefits to males of ejaculate sex peptide (SP) transfer. SP is of interest because it is a candidate for mediating sexual conflict: its frequent receipt reduces female fitness. In single matings with virgin females SP is known to increase egg laying and decrease receptivity. Hence, we predicted that SP could: (i) boost a male's absolute paternity by increasing offspring production and delaying female remating and/or (ii) boost relative paternity share. We tested these predictions using two different lines of SP-lacking males, in both two-mating and free-mating assay conditions. SP transfer conferred higher absolute, but not relative, male reproductive success. In matings with virgin females, SP transfer increased mating productivity and delayed remating and hence the onset of sperm competition. In already mated females, SP transfer did not elevate absolute progeny production, but did increase intermating intervals and hence the period over which a male could gain paternity. Consistent with this, under free-mating conditions over an extended period, we detected a 'per-mating' fitness benefit for males transferring SP. These benefits are consistent with a role for SP in mediating conflict, with SP acting to maximize short-term fitness benefits for males.

A comparative assessment of cartilage and joint fat pad as a potential source of cells for autologous therapy development in knee osteoarthritis

OBJECTIVES

The utility of autologous chondrocytes for cartilage repair strategies in older subjects with osteoarthritis (OA) may be limited by both age-related and disease-associated decline in chondrogenesis. The aim of this work was to assess OA Hoffa's fat pad as an alternative source of autologous chondroprogenitor cells and to compare it with OA chondrocytes derived from different areas of cartilage.

METHODS

Cartilage and fat pad tissue digests were obtained from 26 subjects with knee OA and compared with normal bone marrow (BM) mesenchymal stem cells (MSCs) with respect to their in vitro colony-forming potential, growth kinetics, multipotentiality and clonogenicity. Flow cytometry was used to investigate their MSC marker phenotype.

RESULTS

Expanded cultures derived from eroded areas of cartilage were slightly more chondrogenic than those derived from macroscopically normal cartilage or chondro-osteophytes; however, all cartilage-derived cultures failed to maintain their chondrogenic potency following extended expansion. In contrast, OA fat pads contained highly clonogenic and multipotential cells with stable chondrogenic potency in vitro, even after 16 population doublings. Standard colony-forming assays failed to reflect the observed functional differences between the studied tissues whereas flow cytometry revealed higher levels of a putative MSC marker low-affinity growth factor receptor (LNGFR) on culture expanded fat pad-derived, but not cartilage-derived, MSCs.

CONCLUSIONS

In contrast to OA cartilage from three different sites, OA Hoffa's fat pad contains clonogenic cells that meet the criteria for MSCs and produce multipotential cultures that maintain their chondrogenesis long term. These findings have broad implications for future strategies aimed at cartilage repair in OA.

Exploring the views of second-year Foundation Programme doctors and their educational supervisors during a deanery-wide pilot Foundation Programme

AIM

To explore the views of second-year Foundation Programme doctors (F2s) and their educational supervisors taking part in a deanery-wide pilot Foundation Programme, in order to gain an understanding of their perceptions of the available learning experiences, support and supervision.

METHODS

20 semi-structured interviews were undertaken with randomly selected F2 doctors and educational supervisors participating in the deanery-wide pilot Foundation Programme.

RESULTS

F2 trainees received appropriate and sufficient support and supervision from a variety of sources during their placements; however, it was believed that additional training of educational supervisors was required. Trainees reported some problems with the perception of the role of an F2; further understanding of the purpose and role of the F2 programme is required at trust level. The portfolio was viewed positively as a record and a learning tool, but was thought to be too bureaucratic. Trainees believed that it was more beneficial to their careers to take part in a foundation programme as opposed to a traditional senior house officer post, but both trainees and educational supervisors expressed some concerns about the generic nature of some skills F2s were expected to acquire.

CONCLUSIONS

This evaluation has highlighted successful aspects of the Foundation Programme, particularly with regard to the level of support and range of experiences provided for trainees. Issues of concern to both trainees and educational supervisors have been identified, which require additional understanding.

No evidence that experimental manipulation of sexual conflict drives premating reproductive isolation in Drosophila melanogaster

Theoretical models predict that sexual conflict can drive reproductive isolation by decreasing the probability of matings between individuals from allopatric populations. A recent study in dung flies supported this prediction. To test the generality of this finding we used replicate lines of Drosophila melanogaster that had been selected under high, medium and low levels of sexual conflict, in which the females had evolved differences in their level of resistance to male-induced harm. We compared the proportion of virgin pairs that mated by set time points, for flies from the same replicate within each sexual conflict level vs. flies from different replicates within each sexual conflict level. The results did not support the prediction that, in D. melanogaster, sexual conflict drives population divergence via changes in female willingness to mate. The results were unlikely to be explained by differential inbreeding or by a lack of response to sexual conflict.

The portfolio: how was it for you? Views of F2 doctors from the Mersey Deanery Foundation Pilot

A study was conducted between August 2004 and August 2005 to explore the experiences of Foundation year 2 (F2) trainees who used the learning portfolio on the Mersey Deanery pilot scheme. Seventy-three trainees (77%) reported receiving their portfolio during their induction. In their first four-month placement, 90 trainees (96%) completed the two case-based discussions, 80 (87%) the three mini clinical examinations and 92 (97%) the two direct observation of practical procedures. The number of trainees who felt there was an opportunity to make a record of and analyse clinical critical incidents and critical incidents related to professional behaviour was only 32 (35%) and 13 (15%) respectively. Free text responses suggested that trainees appreciate the portfolio but that an understanding of its content and purpose, particularly by educational supervisors, is paramount to its success.

No detectable genetic correlation between male and female mating frequency in the stalk-eyed fly Cyrtodiopsis dalmanni

There is much interest in explaining why female insects mate multiply. Females of the stalk-eyed fly Cyrtodiopsis dalmanni can mate several times each day in a lifetime which may span several months. There are many adaptive explanations, but one hypothesis that has received little rigorous empirical attention is that female multiple mating has evolved for non-adaptive reasons as a correlated response to selection for high male mating frequency rather than because of direct or indirect benefits accruing to females. We tested this hypothesis in stalk-eyed flies by measuring the mating frequency of females from lines that exhibited a direct response in males to artificial selection for increased ('high') and decreased ('low') male mating frequency. We found that the mating frequency of high-line females did not differ from that of low-line females. Hence, there was no support for a genetic correlation between male and female mating frequency in this species. Our study suggests that the genes which influence remating may not be the same in the sexes, and that females remate frequently in this species to gain as yet unidentified benefits.

Selected culturable enteric bacterial populations are modified by diet acidification and the growth promotant Tylosin

AIMS

To determine the effect of diet acidification and an in-feed antibiotic growth promotant (Tylosin, Ty) on selected culturable bacterial populations in the gastrointestinal tract (GIT) of mice.

METHODS AND RESULTS

Female C57Bl mice were given a standard diet supplemented with Acid Pak (AP) or Ty in the drinking water. After 21 days, lumen and adherent populations of Enterobacteriaceae, enterococci/streptococci, and lactic acid bacteria (LAB) from the ileum, caecum, colon and faeces were enumerated. General intestinal health was assessed by the frequency of haemolytic bacteria in the different intestinal compartments. Contrary to expectations, AP and Ty significantly increased haemolytic bacteria in the lumen of the caecum and colon (P<0.05). The small but significant growth-enhancing effect of Ty (P<0.05) was associated with decreases in enterococci/streptococci and surprisingly, LAB, as well as increases in coliforms. AP, which failed to improve growth rates, reduced coliforms, had limited effects on enterococci/streptococci, and specifically failed to promote the growth of LAB populations in all intestinal compartments. Ty supplementation was also associated with a significant increase in macrolide-resistant enterococci throughout the GIT.

CONCLUSIONS

Dietary acidification is less effective than Ty in modulating the population dynamics of selected culturable populations of enteric bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

The mouse can provide a useful experimental model to examine the effects of new dietary supplements, formulations or regimes on changes in microbial population dynamics, including monitoring for antibiotic resistance.

Rapid identification of virulence genes in enterotoxigenic Escherichia coli isolates associated with diarrhoea in Queensland piggeries

OBJECTIVE

To identify virulence genes in enterotoxigenic E coli (ETEC) isolates associated with diarrhoea in neonatal, 1 to 3 week-old and weaned pigs in southeast Queensland.

DESIGN

Multiplex PCR and serotyping were applied to E coli isolates obtained over a 5-year period (1998-2002) from cases diagnosed at Toowoomba Veterinary Laboratory.

PROCEDURE

A total of 126 isolates from 25 different Queensland piggeries were tested for haemolytic activity on 5% sheep blood agar and by multiplex PCR for the presence of five commonly recognised fimbrial (F4, F5, F6, F41 and F18) and three enterotoxin genes (STa, STb, LT). A subset of 62 representative isolates were serotyped by slide agglutination. For comparative purposes, multiplex PCR was also performed on the DNA of 31 ETEC isolates from 9 serotypes originating from piggeries in southern New South Wales.

RESULTS

A total of 113 (89.7%) of the isolates from Queensland possessed ETEC virulence genes, including 14 of 15 isolates from neonatal pigs (93.3%), 18 of 23 isolates from 1 to 3 week old pigs (78.3%) and 81 of 88 isolates from weaned pigs (92.1%). F4:STa:STb:LT (serotype O149) was the most prevalent pathotype in neonatal and 1-3 week old pigs and F4:STa:STb:LT (serotype O149) and F18:STa:STb:LT (serotype O141) were most prevalent in weaned pigs. In comparison, isolates obtained from neonatal pigs from New South Wales belonged to a more diverse range of pathotypes and serotypes.

CONCLUSION

Multiplex PCR was a rapid and specific method for detecting the presence of ETEC virulence genes in porcine E coli isolates. For isolates obtained from cases of suspected colibacillosis in Queensland, growth of a heavy pure culture of haemolytic E coli was a sensitive prognostic indicator of the presence of ETEC virulence genes in the isolate. ETEC pathotypes and serotypes remained stable in Queensland piggeries over the five-year study period and appear to have changed little over the last three decades.

Direct and correlated responses to artificial selection on male mating frequency in the stalk-eyed fly Cyrtodiopsis dalmanni

Traditionally it was thought that fitness-related traits such as male mating frequency, with a history of strong directional selection, should have little additive genetic variance and thus respond asymmetrically to bidirectional artificial selection. However, recent findings and theory suggest that a balance between selection for increased male mating frequency and opposing selection pressures on physiologically linked traits will cause male mating frequency to have high additive genetic variation and hence respond symmetrically to selection. We tested these hypotheses in the stalk-eyed fly, Cyrtodiopsis dalmanni, in which males hold harems comprising many females and so have the opportunity to mate at extremely high frequencies. We subjected male stalk-eyed flies to artificial selection for increased ('high') and decreased ('low') mating frequency in the presence of ecologically realistic, high numbers of females. High line males mated significantly more often than control or low line males. The direct response to selection was approximately symmetric in the high and low lines, revealing high additive genetic variation for, and no significant genetic constraints on, increased male mating frequency in C. dalmanni. In order to investigate trade-offs that might constrain male mating frequency under natural conditions we examined correlated responses to artificial selection. We measured accessory gland length, testis length and eyespan after 7 and 14 generations of selection. High line males had significantly larger accessory glands than low line males. No consistent correlated responses to selection were found in testis length or eyespan. Our results suggest that costs associated with the production and maintenance of large accessory glands, although yet to be identified, are likely to be a major constraint on mating frequency in natural populations of C. dalmanni.

134 EVALUATION OF APOPTOSIS IN BOVINE EMBRYOS BY FLUORESCENT LABELING OF CASPASES-3 AND -7

Reports indicate that apoptosis is more prevalent in in vitro-produced (IVP) embryos than in in vivo-derived (IVD) embryos. These studies most often utilize the TUNEL procedure to label fragmented DNA. DNA fragmentation, however, is not unique to apoptosis as cells undergoing necrosis also exhibit substantial DNA fragmentation. Also, improper tissue handling has been reported to induce enough DNA fragmentation for TUNEL-positive staining of nuclei. Thus, the objective of this study was to evaluate the presence of caspases-3 and -7 as indicators of apoptosis in bovine fresh IVD embryos (F-IVD; n = 32), frozen-thawed IVD embryos (FT-IVD; n = 32) and IVP embryos cultured in CR1aa (n = 64). Embryos (quality grades, QG = 1 to 4) were evaluated for apoptotic cells by using a fluorescence-based assay for the detection of active caspaces (Caspatag®, Caspase 3,7 In Situ Assay Kit, Chemicon International, Inc., Temecula, CA, USA). To validate this assay, positive controls (PC) were prepared by incubating IVP-embryos in cyclohexamide for 3 to 4 h prior to staining. After staining, embryos were placed on slides and the number of apoptotic cells/embryo were counted. Embryos in which individual fluorescent points were not apparent were categorized as having profuse staining patterns (PSP) and were assigned an arbitrary apoptotic cell value of 20. Data were analyzed using PROC GLM of SAS with a post hoc LSD test. More than 65% of all embryos displayed at least 1 fluorescent cell, regardless of treatment. PC embryos consistently exhibited PSP. Overall, culture conditions did not markedly affect the incidence of apoptosis. FT-IVD embryos had significantly more (P < 0.05) apoptotic cells (8.2 ± 2.9) than F-IVD (0.9 ± 0.3). However, when embryos exhibiting PSP were excluded, the statistical difference was no longer present (1.5 ± 0.9 vs. 0.9 ± 0.3, respectively). It is unclear why some embryos exhibit specific staining patterns while others exhibit PSP, but we hypothesize that PSP embryos are likely degenerate. Interestingly, different degrees of fluorescence were often present within an embryo. Often, small pinpoint areas of fluorescence were detected while other times the fluorescence appeared to consume the entire cytoplasm of the cell. The capase protein has been localized in the cytoplasm of the cell, so the different degrees of fluorescence may represent different degrees of apoptosis. There was no major effect of culture environment on apoptosis when embryos were categorized by QG. Furthermore, within a treatment, there was no significant difference in apoptosis across embryo QG. To our knowledge, this is the first report of apoptosis evaluated in relation to embryo QG. Based on these findings, apoptosis does not appear to be heavily involved in the reduced developmental potential of IVP bovine embryos. The authors would like to sincerely thank Dr. Neil Schrick for his generous donation of frozen in vivo-derived bovine embryos.

Efficacy and tolerability of borage oil in adults and children with atopic eczema: randomised, double blind, placebo controlled, parallel group trial

OBJECTIVE

To study the efficacy and tolerability of borage oil, which contains a high concentration of gamma linolenic acid, in children and adults with atopic eczema.

DESIGN

Single centre, randomised, double blind, placebo controlled, parallel group trial.

SETTING

Acute district general hospital in Nuneaton, England.

PARTICIPANTS

151 patients, of whom 11 failed to return for assessment, leaving an evaluable population of 140 (including 69 children).

INTERVENTION

Adults received four capsules of borage oil twice daily (920 mg gamma linolenic acid), and children received two capsules twice daily, for 12 weeks.

MAIN OUTCOME MEASURES

Change in total sign score at 12 weeks measured with the six area, six sign, atopic dermatitis (SASSAD) score (primary endpoint); symptom scores, assessed on visual analogue scales; topical corticosteroid requirement, assessed on a five point scale; global assessment of response by participants; adverse events and tolerability.

RESULTS

The mean SASSAD score fell from 30 to 27 in the borage oil group and from 28 to 23 in the placebo group. The difference between the mean improvements in the two groups was 1.4 (95% confidence interval -2.2 to 5.0) points in favour of placebo (P = 0.45). No significant differences occurred between treatment groups in the other assessments. Subset analysis of adults and children did not indicate any difference in response. The treatments were well tolerated.

CONCLUSION

Gamma linolenic acid is not beneficial in atopic dermatitis.

Influence of female reproductive anatomy on the outcome of sperm competition in Drosophila melanogaster

Females as well as males can influence the outcome of sperm competition, and may do so through the anatomy of their reproductive tracts. Female Drosophila melanogaster store sperm in two morphologically distinct organs: a single seminal receptacle and, normally, two spermathecae. These organs have different temporal roles in sperm storage. To examine the association between sperm storage organ morphology and sperm competition, we used a mutant type of female with three spermathecae. Although the common measure of sperm competition, P(2), did not differ between females with two and three spermathecae, the pattern of sperm use over time indicated that female morphology did affect male reproductive success. The rate of offspring production by females with three spermathecae rose and fell more rapidly than by females with two spermathecae. If females remate or die before using up second male sperm, then second male reproductive success will be higher when they mate with females with three spermathecae. The results indicate that temporal patterns of sperm use as well as P(2) should be taken into account when measuring the outcome of sperm competition.

Microsatellite analysis reveals remating by wild Mediterranean fruit fly females, Ceratitis capitata

Accurate estimates of remating in wild female insects are required for an understanding of the causes of variation in remating between individuals, populations and species. Such estimates are also of profound importance for major economic fruit pests such as the Mediterranean fruit fly (Ceratitis capitata). A major method for the suppression of this pest is the sterile insect technique (SIT), which relies on matings between mass-reared, sterilized males and wild females. Remating by wild females will thus impact negatively on the success of SIT. We used microsatellite markers to determine the level of remating in wild (field-collected) Mediterranean fruit fly females from the Greek Island of Chios. We compared the four locus microsatellite genotypes of these females and their offspring. Our data showed 7.1% of wild females remated. Skewed paternity among progeny arrays provided further evidence for double matings. Our lowest estimate of remating was 3.8% and the highest was 21%.