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High-intensity laser–plasma interactions produce a wide array of energetic particles and beams with promising applications. Unfortunately, the high repetition rate and high average power requirements for many applications are not satisfied by the lasers, optics, targets, and diagnostics currently employed. Here, we aim to address the need for high-repetition-rate targets and optics through the use of liquids. A novel nozzle assembly is used to generate high-velocity, laminar-flowing liquid microjets which are compatible with a low-vacuum environment, generate little to no debris, and exhibit precise positional and dimensional tolerances. Jets, droplets, submicron-thick sheets, and other exotic configurations are characterized with pump–probe shadowgraphy to evaluate their use as targets. To demonstrate a high-repetition-rate, consumable, liquid optical element, we present a plasma mirror created by a submicron-thick liquid sheet. This plasma mirror provides etalon-like anti-reflection properties in the low field of 0.1% and high reflectivity as a plasma, 69%, at a repetition rate of 1 kHz. Practical considerations of fluid compatibility, in-vacuum operation, and estimates of maximum repetition rate are addressed. The targets and optics presented here demonstrate a potential technique for enabling the operation of laser–plasma interactions at high repetition rates.
The objective of this study was to investigate the impact of the most commonly cited factors that may have influenced infants’ gut microbiota profiles at one year of age: mode of delivery, breastfeeding duration and antibiotic exposure. Barcoded V3/V4 amplicons of bacterial 16S-rRNA gene were prepared from the stool samples of 52 healthy 1-year-old Australian children and sequenced using the Illumina MiSeq platform. Following the quality checks, the data were processed using the Quantitative Insights Into Microbial Ecology pipeline and analysed using the Calypso package for microbiome data analysis. The stool microbiota profiles of children still breastfed were significantly different from that of children weaned earlier (P<0.05), independent of the age of solid food introduction. Among children still breastfed, Veillonella spp. abundance was higher. Children no longer breastfed possessed a more ‘mature’ microbiota, with notable increases of Firmicutes. The microbiota profiles of the children could not be differentiated by delivery mode or antibiotic exposure. Further analysis based on children’s feeding patterns found children who were breastfed alongside solid food had significantly different microbiota profiles compared to that of children who were receiving both breastmilk and formula milk alongside solid food. This study provided evidence that breastfeeding continues to influence gut microbial community even at late infancy when these children are also consuming table foods. At this age, any impacts from mode of delivery or antibiotic exposure did not appear to be discernible imprints on the microbial community profiles of these healthy children.
This study aimed to evaluate levels of beef cow fertility using calving interval (CI; measured in days) as a measure, and investigate the effects of breed, season, year and progeny gender on CI. The CI data included 273 764 records collected between 1997 and 2012 and included the seven most common breeds (and their crosses) in Northern Ireland (Charolais, Limousin, Belgian Blue, Simmental, Blonde d’Aquitaine, Aberdeen Angus and Hereford), accounting for 94.1% of beef dams recorded. Mean CI for all cows was 395 days, 30 days longer than the optimum 365 days. Charolais and Belgian Blue dams had the longest CI (P<0.05). Cows older than 144 months had a longer CI (P<0.05) compared with cows younger than 144 months. Charolais sires had a shorter subsequent CI of 392 days (P<0.05) compared with the other breeds. Cows calving in June had the shortest subsequent CI (376 days; P<0.05), whereas cows calving in November had the longest subsequent CI (410 days). Progeny gender did not significantly affect CI. This study establishes the level of beef cow fertility using CI as a measure in Northern Ireland is sub optimal and there are opportunities for improvement. Factors identified as influencing CI included dam breed, sire breed and month of parturition. This knowledge can be used to direct breeding programmes and inform knowledge transfer protocol to improve sustainability of beef production.
To assess the impact of farm management on herd fertility, a survey of 105 beef farms in Northern Ireland was conducted to establish the relationship between management variables and fertility. Each herd's average calving interval (CI) and the proportion of cows with a CI > 450 days (extended calving interval, ECI) was calculated to establish herd fertility. The relationship between each response variable (CI and proportion ECI) and each explanatory variable (respondents’ answers to questionnaire) was examined using univariate linear regression analyses. All response variables found to be associated with the explanatory variables were modelled against each group in turn using a fully automated multivariate stepwise regression algorithm employing the method of forward selection with backward elimination. The optimum 365-day CI and a proportion of 0 cows per hundred calved ECI targets were not widely attained in the current study. The distribution of CI and proportion ECI in the current study suggests more realistic targets would be a 379-day CI and 5 cows per hundred calved with ECI in commercial beef breeding herds. Six management factors were found to be associated with herd fertility: herd vaccination, bull selection, fertility management, breeding female management, perception of extension service (rural education provided by the government) and record keeping. It was found that respondents who vaccinated cows had a reduction of 5 cows per hundred calved in the proportion of cows with ECI, and as the number of vaccines administered to a cow increased, the CI decreased. Regular vaccination of breeding bulls was associated with a 9-day reduction in CI. Bull selection strategy had several associations with herd fertility; most notable was that respondents who used visual selection rather than estimated breeding values (EBVs) to select bulls were found to have a 15-day longer CI and 7 cows per hundred calved higher proportion of cows with ECI. For each 0·01 increase in the proportion of cows served by artificial insemination, CI increased by 0·16 days. Respondents who rated their beef breeding herd fertility as ‘very good’ had lower ECI and CI than those who rated beef breeding herd fertility as poor or satisfactory. Condition scoring of cows at weaning lowered ECI by 5 cows per hundred calved. Those who perceived the extension service to be very useful had the lowest CI and lowest ECI. Respondents who did not keep a record of CI to assess herd fertility had an 11-day longer CI and 6 cows per hundred calved higher proportion ECI than those who did not. In conclusion, the survey found a number of important variables linked to improved fertility including selecting sires based on EBVs and using a robust vaccination programme.
The Vlasov–Maxwell equations possess a Hamiltonian structure expressed in terms of a Hamiltonian functional and a functional bracket. In the present paper, the transformation (‘lift’) of the Vlasov–Maxwell bracket induced by the dynamical reduction of single-particle dynamics is investigated when the reduction is carried out by Lie-transform perturbation methods. The ultimate goal of this work is to provide an explicit pathway to the Hamiltonian formulations for the guiding-centre and gyrokinetic Vlasov–Maxwell equations, which have found important applications in our understanding of turbulent magnetized plasmas. Here, it is shown that the general form of the reduced Vlasov–Maxwell equations possesses a Hamiltonian structure defined in terms of a reduced Hamiltonian functional and a reduced bracket that automatically satisfies the standard bracket properties.
Tail docking of pigs is commonly performed to reduce the incidence of unwanted tail-biting behaviour. Two docking methods are commonly used: blunt trauma cutting (i.e. using side clippers), or cutting and concurrent cauterisation using a hot cautery iron. A potential consequence of tail amputation is the development of neuromas at the docking site. Neuromas have been linked to neuropathic pain, which can influence the longer-term welfare of affected individuals. To determine whether method of tail docking influences the extent of neuroma formation, 75 pigs were allocated to one of three treatments at birth: tail docked using clippers; tail docked using cautery iron; tail left intact. Tail docking was performed at 2 days of age and pigs were kept under conventional conditions until slaughter at 21 weeks of age. Tails were removed following slaughter and subjected to histological examination. Nerve histomorphology was scored according to the following scale: 1=discrete well-organised nerve bundles; 2=moderate neural proliferation and disorganisation affecting more than half of the circumference of the tail; 3=marked neural proliferation to form almost continuous disorganised bundles or non-continuous enlarged bundles compressing the surrounding connective tissue. Scores of 2 or 3 indicated neuroma formation. Scores were higher in docked pigs than undocked pigs (P<0.001), but did not differ between pigs docked using clippers and those docked using cautery (P=0.23). The results indicate that tail docking using either clippers or cautery results in neuroma formation, thus having the potential to affect long-term pig welfare.
A new micrometer has been in operation on the Carlsberg Automatic Meridian Circle since May 1988. The zenith mean error for one observation has improved from O.″19 to 0.″14 and the limiting magnitude from 13m.2 to 14m.8. The first meridian observations of Pluto and observations of nine extragalactic objects are briefly discussed.
The Medium-l Program of the Michelson Doppler Imager (MDI) instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∼ 300. The initial results show that the noise in the Medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. In a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer.
The president thanks those members contributing material to this report. The volume of the material necessitated some editing, but no substantive omissions occurred. Whenever available, AAA numbers are used in lieu of complete titles of publications to help conserve space.
IAU Symposium No. 109 Astrometric Techniques, was held in Gainesville, Florida in January 1984. Although the Proceedings of that meeting are not now available (January 1935), ccmnission members and other interested parties are urged to secure access to that voline when it appears since so many facets of the commission’s work are addressed therein.
The discovery of the fully developed Formative sites of Cotocallao (ca. 3750-2350 cal. B.P.) in the Quito Basin and La Chimba (ca. 2650-1700 cal. B.P.) in the northern highlands of Ecuador has raised questions about their cultural antecedents, which have not been resolved despite decades of archaeological work in the region. Paleoenvironmental coring investigations were conducted at Lake San Pablo in northern highland Ecuador to determine the date for the onset of prehistoric maize farming in the temperate highland valleys of this region. The investigations included analysis of lake sediments for pollen, phytoliths, diatoms, and tephra. Maize pollen was identified as early as 4900 cal. B.P., while maize phytoliths dated even earlier, to 6200 or 6600 cal. B.P. These results demonstrate a long history of maize farming in valleys around Lake San Pablo, but in the context of a punctuated record of major and minor volcanic eruptions. It is concluded that early horticultural sites predating Cotocallao and La Chimba must exist, but to find such sites, archaeologists will have to locate and study deeply buried A-horizon soils.
Paranoia is one of the commonest symptoms of psychosis but has rarely been studied in a population at risk of developing psychosis. Based on existing theoretical models, including the proposed distinction between ‘poor me’ and ‘bad me’ paranoia, we aimed to test specific predictions about associations between negative cognition, metacognitive beliefs and negative emotions and paranoid ideation and the belief that persecution is deserved (deservedness).
We used data from 117 participants from the Early Detection and Intervention Evaluation for people at risk of psychosis (EDIE-2) trial of cognitive–behaviour therapy, comparing them with samples of psychiatric in-patients and healthy students from a previous study. Multi-level modelling was utilized to examine predictors of both paranoia and deservedness, with post-hoc planned comparisons conducted to test whether person-level predictor variables were associated differentially with paranoia or with deservedness.
Our sample of at-risk mental state participants was not as paranoid, but reported higher levels of ‘bad-me’ deservedness, compared with psychiatric in-patients. We found several predictors of paranoia and deservedness. Negative beliefs about self were related to deservedness but not paranoia, whereas negative beliefs about others were positively related to paranoia but negatively with deservedness. Both depression and negative metacognitive beliefs about paranoid thinking were specifically related to paranoia but not deservedness.
This study provides evidence for the role of negative cognition, metacognition and negative affect in the development of paranoid beliefs, which has implications for psychological interventions and our understanding of psychosis.
The drinking water infrastructure in the United States is ageing; extreme weather events place additional stress on water systems that can lead to interruptions in the delivery of safe drinking water. We investigated the association between household exposures to water service problems and acute gastrointestinal illness (AGI) and acute respiratory illness (ARI) in Alabama communities that experienced a freeze-related community-wide water emergency. Following the water emergency, investigators conducted a household survey. Logistic regression models were used to estimate adjusted prevalence ratios (aPR) and 95% confidence intervals (CI) for self-reported AGI and ARI by water exposures. AGI was higher in households that lost water service for ⩾7 days (aPR 2·4, 95% CI 1·1–5·2) and experienced low water pressure for ⩾7 days (aPR 3·6, 95% CI 1·4–9·0) compared to households that experienced normal service and pressure; prevalence of AGI increased with increasing duration of water service interruptions. Investments in the ageing drinking water infrastructure are needed to prevent future low-pressure events and to maintain uninterrupted access to the fundamental public health protection provided by safe water supplies. Households and communities need to increase their awareness of and preparedness for water emergencies to mitigate adverse health impacts.
This paper presents the results of an investigation into the mortality and marriage experience of six widows' funds of the Scottish Banks over the period 1950 to 1966 and compares the results with similar investigations which have been made in the past. Tables of mortality rates have been produced for bachelors, married men, widowers, married men and widowers combined, all males, wives and widows, and marriage rates have been produced for bachelors, widowers and widows.
The examination of the male mortality experience shows a substantial improvement over the previous 1923-43 investigation and in general terms demonstrates that widowers' mortality may be expected to be heavier than that of bachelors which in turn is likely to be heavier than that of married men. Women's mortality also shows considerable improvement but widows' mortality is heavier than wives' mortality at all ages.
The trend towards higher marriage rates and towards marriage at younger ages which was so marked in the previous investigation has continued unabated and the marriage rates for bachelors for the period 1962-66, which have been used for calculating the appropriate monetary functions, demonstrate this trend when compared with the rates for the whole period and with the results of previous investigations.
Monetary functions to enable valuations to be made of widows' funds at 5% interest by the reversionary method are published in the paper together with the results of valuing a model fund by this method using various assumptions. The result of valuing the model fund using the collective method is shown for comparison.