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We use experimental methods to investigate subsidy incidence, the transfer of subsidy payments from intended recipients to other economic agents, in privately negotiated spot markets. Our results show that market outcomes in treatments with a subsidy given to either buyers or sellers are significantly different from both a no-subsidy treatment and the competitive prediction of a 50% subsidy incidence. The disparity in incidence across treatments relative to predicted levels suggests that incidence equivalence does not hold in this market setting. Moreover, we find no statistical difference in market outcomes when benefits are framed as a “subsidy” versus a schedule shift.
Studies involving clinically recruited samples show that genetic liability to schizophrenia overlaps with that for several psychiatric disorders including bipolar disorder, major depression and, in a population study, anxiety disorder and negative symptoms in adolescence.
We examined whether, at a population level, association between schizophrenia liability and anxiety disorders continues into adulthood, for specific anxiety disorders and as a group. We explored in an epidemiologically based cohort the nature of adult psychopathology sharing liability to schizophrenia.
Schizophrenia polygenic risk scores (PRSs) were calculated for 590 European-descent individuals from the Christchurch Health and Development Study. Logistic regression was used to examine associations between schizophrenia PRS and four anxiety disorders (social phobia, specific phobia, panic disorder and generalised anxiety disorder), schizophrenia/schizophreniform disorder, manic/hypomanic episode, alcohol dependence, major depression, and – using linear regression – total number of anxiety disorders. A novel population-level association with hypomania was tested in a UK birth cohort (Avon Longitudinal Study of Parents and Children).
Schizophrenia PRS was associated with total number of anxiety disorders and with generalised anxiety disorder and panic disorder. We show a novel population-level association between schizophrenia PRS and manic/hypomanic episode.
The relationship between schizophrenia liability and anxiety disorders is not restricted to psychopathology in adolescence but is present in adulthood and specifically linked to generalised anxiety disorder and panic disorder. We suggest that the association between schizophrenia liability and hypomanic/manic episodes found in clinical samples may not be due to bias.
Highly luminescent thin films of zinc tungstate (ZT) have been deposited on top of conventional scintillators (Yttrium Aluminum Perovskite, Yttrium Aluminum Garnet) for electron detection in order to replace the need for a top conducting layer, such as indium tin oxide (ITO) or aluminum, which is non-scintillating and electron absorbing. Such conventional conducting layers serve the single purpose of eliminating electrical charge build-up on the scintillator. The ZT film also eliminates charging, which has been verified by measuring the Duane–Hunt limit and electron emission versus accelerating voltage. The luminescent nature of the ZT film ensures effective detection of low energy electrons from the very top surface of the structure ZT/scintillator, which we call “first-surface scintillator”. The cathodoluminescence has been measured directly with a photodetector and spectrally resolved at different accelerating voltages. All results demonstrate the extended range of operation of the first-surface scintillator, while the conventional scintillators with a top ITO layer decline below 5 kV and have practically no output below 2 kV. Scintillators of different types were integrated in a detection system for backscattered electrons (BSE). The quality of the image at high accelerating voltages is comparable with the conventional scintillator and commercial BSE detector, while the image quality at 1 kV from the first-surface scintillator is superior.
The triazines are one of the most widely used herbicide classes ever developed and are critical for managing weed populations that have developed herbicide resistance. These herbicides are traditionally valued for their residual weed control in more than 50 crops. Scientific literature suggests that atrazine, and perhaps other s-triazines, may no longer remain persistent in soils due to enhanced microbial degradation. Experiments examined the rate of degradation of atrazine and two other triazine herbicides, simazine and metribuzin, in both atrazine-adapted and non-history Corn Belt soils, with similar soils being used from each state as a comparison of potential triazine degradation. In three soils with no history of atrazine use, the t1/2 of atrazine was at least four times greater than in three soils with a history of atrazine use. Simazine degradation in the same three sets of soils was 2.4 to 15 times more rapid in history soils than non-history soils. Metribuzin in history soils degraded at 0.6, 0.9, and 1.9 times the rate seen in the same three non-history soils. These results indicate enhanced degradation of the symmetrical triazine simazine, but not of the asymmetrical triazine metribuzin.
A previous study (Mauricio et al., 1998) with 12 forage substrates (straw, hay and dried grasses) showed a high correlation between rumen liquor and faeces for total gas production and in vitro organic matter digestibility (OMD). However parameters estimated using faecal inoculum were generally lower man when using rumen liquor. To confirm this observation, a second study was conducted using maize silage and silages made from maize plant fractions.
The experiment was conducted using a range of forages with accurately predetermined OMD values (ADAS) to compare rumen liquor (RL) and faeces (FA) as sources of inocula in the pressure transducer technique (PTT) (Theodorou et al., 1994). Gas production results were examined in relation to OMD determined in vitro (PTT, Tilley and Terry) and in vivo.
Several published reports on the nutritive value of whole-crop wheat (WCW) have been based on estimations from laboratory techniques, some of which were developed for grass silage. However, there is little information on the accuracy of such estimations. Therefore the aim of this study was to evaluate the suitability of predicting the in vivo digestibility of WCW from various less animal-dependent techniques.
Menke et al. (1979), Beuvink et al. (1992) and Theodorou et al. (1994) developed techniques for measuring the time course of gas production of foods fermented in vitro with rumen fluid. These techniques require description of the fermentation profile with an appropriate mathematical model. Although several authors have used these techniques to study the ruminal fermentation of foods, little information is available on the suitability of the model chosen for describing the fermentation profile of the food under study. In this study, the models of Ørskov and McDonald (1979), France et al. (1993) and Beuvink and Kogut (1993) were fitted to the in vitro gas production profiles of 10 whole-crop wheat (WCW) forages (cv. Slepjner) to determine the model most suited to describing the data.
At maintenance at least, the whole tract digestibility of several foods in sheep and cattle is similar, consequently much of the information on the nutritive value of dairy cow foods in food composition tables is derived from studies conducted in sheep. However, Adesogan (1996) reported that in whole-crop wheat (WCW), starch digestibility is higher in sheep than in dairy cows. This study examined the validity of using sheep to model the ruminal degradation of WCW in cows by comparing the degradability of dry matter (DM) and nitrogen (N) of urea-treated WCW in both species.
Winter wheat (cv. Hussar) was harvested at 540 g DM per kg and conserved following urea application at target rates of 20 or 40g/kg DM (WCW2 and WCW4 respectively). The degradability of the forages was examined in dairy cows given 6 kg dairy concentrate and grass silage ad libitum and in wethers given 2.4 kg/day of grass silage supplemented with 0.36kg/day of rolled, mineralized barley.
In the Central Kenyan Highlands, dairy cattle ownership is a crucial element in poverty alleviation. For example, in Kiambu district just north of Nairobi, out of the population of 744010, 48% of 189709 households stall feed dairy cattle. Farm sizes average 1.1 to 2.0 ha per household. Producing sufficient forage for dairy cattle is difficult and low dry matter intake constrains dairy production and there is a positive correlation between stover intake and milk yield.. Napier grass comprised 40% of the total dry matter fed to cattle and maize forage 24% according to the project’s Rapid Rural Appraisal, maize thinnings and stover being routinely fed to livestock. In another survey, dry maize stover accounted for nearly 65% of dry matter intake of dairy cattle during October.
This text book was conceived in January 2002, in Tanzania, during a DFID Livestock Production Programme (LPP) workshop. Perceived justifications for such a book were: (1) to improve the preparation of animal science students to address livestock issues faced by resource-poor subsistence farmers in developing countries; the majority of livestock text-books are either a) authored in the ‘north’ and based on temperate, large-scale, commercial systems or b) based on a single species and technology ‘fix’ approach, with insufficient focus on the systems under which livestock are kept by the resource-poor, or on improving livestock survival and productivity and understanding the contribution they make to livelihoods; (2) to address the UN Millennium Development Goal of halving the number of people living in absolute poverty by 2015 through `training teachers’ using appropriate information. Three quarters of poor people live in rural areas and keep livestock; (3) to respond to the large demand for meat and milk over the next 20 years foreseen by the burgeoning ‘Livestock Revolution’ and the consequent opportunities for resource-poor livestock keepers to move from subsistence to a market-oriented economy. The LPP agreed to commission the book provided that consultation with stakeholders confirmed a demand for it and that a broad electorate of stakeholders participated in the book’s design and production. Two editors (E. Owen and T Smith) were appointed to undertake the consultations and subsequent production of the book in collaboration with the Manager of LPP (J.I. Richards).
Production from smallholder owned goats in the semi-arid tropics is constrained by dry season feed shortages. Kid mortality is high and low growth rate of kids weaned at the onset of the dry season delays slaughtering of males and breeding in females. Supplementation with purchased feed is unaffordable so only locally available, probably non-conventional feeds can be considered. In Southern Zimbabwe, the typical natural vegetation in communal grazing areas consists of annual and perennial grasses and trees and shrubs, many of which are Acacia species. In this project tree fruits, from Acacia and other available species were evaluated as dry season protein supplements for goats.
A major criticism of in vitro gas systems is that measurement of nutritionally wasteful products (i.e. CH4 and CO2, either directly from fermentation or indirectly from neutralization of VFA by the bicarbonate buffer) provides little useful information. However, as VFA and gas production are inversely related to microbial biomass yield for any given unit of substrate degraded, it has been suggested (e.g. Getachew et al., 1998) that an estimate of fermentation efficiency or partitioning factor (PF) can be obtained by relating gas production (ml) to the extent of degradation (mg). This study examined the relationship between in vitro DOMD, gas release and PF values using data obtained from an assessment of four maize silages.
After prolonged exposure to tanniniferous diets, it has been reported that some rumen microorganisms acquire defensive mechanisms against tannins (Brooker et al., 2000) or produce tannin-degrading enzymes. Such rumen microorganisms are said to be “tannin resistant” as their fermentation activity is less inhibited by the presence of tannins in the host’s diet. As acacia pods contain tannins their use as protein supplements for goats in the dry season may require that they be first detannified e.g. by using polyethylene glycol (PEG). However, goats with prior exposure to tanniniferous diets may have developed adaptive mechanisms to deal with tannins. This study, therefore, investigated the need for tannin inactivation in feeds given to ‘adapted’ animals by comparing the effect on the in vitro fermentation of tree pods incubated with and without PEG using rumen fluid from adapted and unadapted goats.
Carcass conformation has been found to be associated with fatness among carcasses of similar weight and subjectively assessed fat cover (Kempster et al., 1981), leading these authors to suggest that assessments of conformation in live animals were even more likely to be confounded with fatness. Consequently, selection for improved shape would likely be opposed to the overall objective of reduced fatness in lamb carcasses. However, conformation remains a highly valued trait among lamb producers and breeders. In principle, shape can also be related to variation in lean: bone ratio and muscularity, defined as the depth of muscle relative to the skeletal dimension. The objectives of this work were to compare a live animal assessment of the conformation of the hind leg and ultrasonic measures of muscle and fat depths as predictors of carcass composition and muscularity.
Fermentation of the increasingly energy-dense rations offered to meet the nutrient demands of today's high yielding dairy cows ought to adversely rumen fibre degradation. Not only could rumen fluid pH be depressed below that assumed critical to cellulolysis for extended periods of time but the quantity of readily fermentable carbohydrate available will further exacerbate this effect. These, together with the reduced rumen retention time of feed particles associated with high feeding levels could significantly limit fibre degradation. This in vitro study was designed to identify the pH at which degradation becomes impaired, the extent of this depression and whether the effect varies according to the feedstuffs offered.
The semi-automated Reading Pressure Technique (RPT, Mauricio et al. 1998) combines gas production profiles and both rate and extent of degradation to evaluate feedstuffs in vitro. The simplicity, low initial cost and high capacity of the system (75 treatments with 4 replicates plus controls can be examined per run) allow it to be widely applied. However, and in common with many other in vitro systems, little information had been generated regarding either its sensitivity or precision. This paper describes how pure substrates were used to identify the minimum amount of fermentable material required to develop distinct degradation profiles. Substitution techniques examined whether changes in degradability at either the mono- or polysaccharide level could be detected and quantified, and replication of these studies provided data regarding precision of the system.
Schizophrenia is a highly heritable disorder, linked to several structural abnormalities of the brain. More specifically, previous findings have suggested that increased gyrification in frontal and temporal regions are implicated in the pathogenesis of schizophrenia.
The current study included participants at high familial risk of schizophrenia who remained well (n = 31), who developed sub-diagnostic symptoms (n = 28) and who developed schizophrenia (n = 9) as well as healthy controls (HC) (n = 16). We first tested whether individuals at high familial risk of schizophrenia carried an increased burden of trait-associated alleles using polygenic risk score analysis. We then assessed the extent to which polygenic risk was associated with gyral folding in the frontal and temporal lobes.
We found that individuals at high familial risk of schizophrenia who developed schizophrenia carried a significantly greater burden of risk-conferring variants for the disorder compared to those at high risk (HR) who developed sub-diagnostic symptoms or remained well and HC. Furthermore, within the HR cohort, there was a significant and positive association between schizophrenia polygenic risk score and bilateral frontal gyrification.
These results suggest that polygenic risk for schizophrenia impacts upon early neurodevelopment to confer greater gyral folding in adulthood and an increased risk of developing the disorder.
22q11.2 deletion syndrome (22q11.2DS) is associated with a high risk of childhood as well as adult psychiatric disorders, in particular schizophrenia. Childhood cognitive deterioration in 22q11.2DS has previously been reported, but only in studies lacking a control sample.
To compare cognitive trajectories in children with 22q11.2DS and unaffected control siblings.
A longitudinal study of neurocognitive functioning (IQ, executive function, processing speed and attention) was conducted in children with 22q11.2DS (n = 75, mean age time 1 (T1) 9.9, time 2 (T2) 12.5) and control siblings (n = 33, mean age T1 10.6, T2 134).
Children with 22q11.2DS exhibited deficits in all cognitive domains. However, mean scores did not indicate deterioration. When individual trajectories were examined, some participants showed significant decline over time, but the prevalence was similar for 22q11.2DS and control siblings. Findings are more likely to reflect normal developmental fluctuation than a 22q11.2DS-specific abnormality.
Childhood cognitive deterioration is not associated with 22q11.2DS. Contrary to previous suggestions, we believe it is premature to recommend repeated monitoring of cognitive function to identifying individual children with 22q11.2DS at high risk of developing schizophrenia.
Values of D/H measured in the methane on the giant planets and Titan indicate the presence of two distinct reservoirs of deuterium in the outer solar system. The dominant reservoir is in hydrogen gas, the second, multi-component reservoir is found in the hydrogen that is bound in condensed compounds. Both reservoirs appear to have originated in the interstellar medium. In contrast, the values of D/H in water vapor on Mars and Venus (especially) exhibit a large enrichment from the “condensed matter” starting value. Interpretation of this enrichment may illuminate the history of water on these two planets.