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It is known that if rats learn that a cue reliably precedes eating, its presentation can cause them to initiate a feeding bout when they are apparently sated (Weingarten, 1983, 1985). However, it is currently unclear precisely how such conditioned cues affect appetite. For example, does this type of conditioning elicit food specific appetites or do individuals merely experience a general increase in feeding motivation (Mela & Rogers, 1998)? To address this issue, the present experiment investigated the hypothesis that exposure to a cue (conditioned stimulus: CS) previously paired with a specific food biases diet selection in favour of that food when an individual is given a choice. The objective of the experiment was to enhance our understanding of the behavioural control of feeding, and hence our ability to predict diet selection and food intake.
The experimental subjects were 12 male Lister-hooded rats (initial body-weight 233; SD=20g). Throughout the experiment the subjects were maintained on a 1lh:13h light:dark cycle with lights on at 0700h, and had ad libitum access to a standard laboratory diet during the light phase.
Analysis of the total surface energy γT and its three components as established by the van Oss-Chaudhury-Good Theory (vOCG) is conducted via Three Liquid Contact Angle Analysis (3LCAA). γT is correlated with the composition of the top monolayers (ML) obtained from High-Resolution Ion Beam Analysis (HR-IBA). Control of γT enables surface engineering for wafer bonding (Nano-BondingTM) and/or epitaxial growth. Native oxides on boron-doped p-Si(100) are found to average γT of 53 ± 1.4 mJ/m2) and are always hydrophilic. An HF in methanol or aqueous HF etch for 60 s always renders Si(100) hydrophobic. Its γT decreases by 20% to 44 ± 3 mJ/m2 in HF in methanol etch and by 10% to 48 ± 3 mJ/m2 in aqueous HF. On the contrary, GaAs(100) native oxides are found to always be hydrophobic. Tellurium n+-doped GaAs(100) yields an average of γT of 37 ± 2 mJ/m2, 96% of which is due to the Lifshitz-Van der Waals molecular interactions (γLW = 36 ± 1 mJ/m2). However, hydrophobic GaAs(100) can be made highly hydrophilic. After etching, γT increases by almost 50% to 66 ± 1.4 mJ/m2. 3LCAA shows that the γT increase is due to electron acceptor and donor interactions, while the Lifshitz-van der Waals energy γLW remains constant. IBA combining the 3.039 ± 0.01 MeV oxygen nuclear resonance with <111> channeling, shows that oxygen on Si(100) decreases by 10% after aqueous HF etching, from 13.3 ± 0.3 monolayers (ML) to 11.8 ± 0.4 ML 1 hour after etch.Te-doped GaAs(100) exhibits consistent oxygen coverage of 7.2 ± 1.4 ML, decreasing by 50% after etching to a highly hydrophilic surface with 3.6 ± 0.2 oxygen ML. IBA shows that etching does not modify the GaAs surface stoichiometry to within 1% . Combining 3LCAA with HR-IBA provides a quantitative metrology to measure how GaAs and Si surfaces can be altered to a different hydroaffinity and surface termination.
The effects of crystal orientation and doping on the surface energy, γT, of native oxides of Si(100) and Si(111) are measured via Three Liquid Contact Angle Analysis (3LCAA) to extract γT, while Ion Beam Analysis (IBA) is used to detect Oxygen. During 3LCAA, contact angles for three liquids are measured with photographs via the “Drop and Reflection Operative Program (DROP™). DROP™ removes subjectivity in image analysis, and yields reproducible contact angles within < ±1°. Unlike to the Sessile Drop Method, DROP can yield relative errors < 3% on sets of 20-30 drops. Native oxides on 5 x 1013 B/cm3 p- doped Si(100) wafers, as received in sealed, 25 wafer teflon boats continuously stored in Class 100/ISO 5 conditions at 24.5°C in 25% controlled humidity, are found to be hydrophilic. Their γT, 52.5 ± 1.5 mJ/m2, is reproducible between four boats from three sources, and 9% greater than γT of native oxides on n- doped Si(111), which averages 48.1 ± 1.6 mJ/m2 on four 4” Si(111) wafers. IBA combining 16O nuclear resonance with channeling detects 30% more oxygen on native oxides of Si(111) than Si(100). While γT should increase on thinner, more defective oxides, Lifshitz-Van der Waals interactions γLW on native oxides of Si(100) remain at 36 ± 0.4 mJ/m2, equal to γLW on Si(111), 36 ± 0.6 mJ/m2, since γLW arises from the same SiO2 molecules. Native oxides on 4.5 x 1018 B/cm3 p+ doped Si(100) yield a γT of 39 ± 1 mJ/m2, as they are thicker per IBA. In summary, 3LCAA and IBA can detect reproducibly and accurately, within a few %, changes in the surface energy of native oxides due to thickness and surface composition arising from doping or crystal structure, if conducted in well controlled clean room conditions for measurements and storage.
The development of adverse behaviour in group–housed growing/ finishing pigs with intact tails was studied in a straw–flow housing system and in a part–slatted system with a commercial enrichment object. Food intake, body weight and behaviour were monitored over the finishing period, with tail biting outbreaks defined as an occasion where three or more pigs within a group had freshly damaged tails and tail biting behaviour was ongoing. Data from the two systems were analysed to identify tail–biting outbreaks and behavioural changes over time. Levels of pig manipulation were higher in the part–slatted system. Over time, pigs in both systems showed reduced interest in the enrichment provided, but not in each other. Despite the presence of the enrichment device, tail biting occurred in all groups in the part–slatted system, but only 1/12 groups in the straw–flow system. The amount of time occupied by manipulation of the enrichment provided was very significantly higher for straw than for the commercial object. Better design of enrichment strategies is therefore needed and should be based on species–relevant requirements.
Legislation in the United Kingdom states that all pigs should have access to straw or other material or object suitable to satisfy their behavioural needs (Welfare of Livestock Regulations, 1994). However, the use of straw bedding has not been universally adopted as its use is incompatible with housing systems which contain perforated flooring, and 76% of pig producers in the UK currently employ fully- or part-slatted finishing housing systems. The aim of this study was to investigate whether different lengths of chopped straw would achieve enhancements in pig welfare, by exploring the possibility that small quantities of chopped straw, in preference to unchopped straw, could constitute adequate provision in part- and fully-slatted systems, thus avoiding the blockage of perforated flooring.
The mixing of unfamiliar sows at weaning leads to aggression whilst dominance hierarchies within the group are established (Kay et al, 1999). The objective of this study was to determine whether the presence of a boar would reduce the incidence of aggression and level of skin damage of newly mixed sows. The overall aim of the project was to improve welfare by designing a suitable strategy for mixing groups of newly-weaned sows
UK legislation dictates that all pigs shall have access to straw or other material or object suitable to satisfy their behavioural needs (Welfare of Livestock Regulations, 1994). However, it is unknown how much straw must be provided to be behaviourally rewarding, and whether pigs’ prior experience of straw can impact upon their subsequent behavioural needs. Therefore, the aim of the current experiment was to investigate these issues by exposing pigs which did, or did not, have prior experience of straw to four levels of straw bed depth.
The mixing of unfamiliar sows at weaning forces the establishment of dominance hierarchies, which frequently involves aggression (Kay et al, 1999). The objective of this study was to determine whether different stocking densities and pen shapes would reduce the incidence of aggression and levels of skin damage. The ultimate aim was to design a mixing pen which could be used to enhance the welfare of groups of newly-weaned sows.
Providing environmental enrichment to farmed animals such as pigs is very important to safeguard their welfare. Current legislation specifies that all pigs must have permanent access to a sufficient quantity of material to enable proper investigation and manipulation activities. Straw has always been regarded as a functional form of enrichment for pigs, but can be difficult to use in slatted housing systems. Alternative enrichment objects might be acceptable substitutes, provided they are designed according to characteristics which pigs find important (Van de Weerd et al., 2003), as pigs may lose interest in simple devices. Most enrichment studies have focussed on immediate effects on behaviour, but it is also important to find out whether there are critical periods where providing enrichment will have effects later in life. The aim of the present study was to investigate whether early life enrichment had an effect on the behavioural development of pigs. To assess this, pigs were tested on an Elevated Plus Maze (EPM) at 10 weeks of age. The EPM is a well-validated anxiety model in rodents, which has more recently been used in pigs. It provides a way to separate fear of novelty (avoidance of open arms) and activity-related elements (entries into closed arms) (Anderson et al., 2000).
Previous research into free-farrowing systems for pigs has found that although sow welfare is better than in crated systems, piglet mortality levels are often unacceptably high. Whilst on-going research programmes are investigating methods to address this problem, the effect of alternative farrowing systems on piglet behaviour and welfare post-weaning is largely unknown. A recent study found that the increased social contact between piglets reared outdoors prior to weaning resulted in welfare benefits post-weaning (Cox and Cooper, 1999). The aim of this experiment was to investigate whether offering different degrees of social contact in an indoor community-lactation system would confer similar enhancements to piglet welfare post-weaning.
The general well-being of growing pigs is known to be affected by both the quantity/quality of stockperson input invested and the complexity of their housing environment (Pearce et. al., 1989). However, the nature of the interactions which exist between these two factors is still largely unknown. The aim of this experiment was to investigate the separate and interactive effects of handling and environmental enrichment on the welfare and performance of growing pigs.
Weaning is associated with a dramatic change in the nutritional status of young animals, and many neonates experience a lag in their normal trajectory of growth post-weaning because they have little experience of ingesting solid food. In the wild, animals are able to learn which foods are ‘safe’ through the mammary transfer of volatile flavours present in the maternal diet. This mechanism could be harnessed in a commercial environment by the use of flavour imprinting, a technique where a characteristic flavour is included both in the maternal and weanling's diet (for pilot data see Campbell, 1976). The use of this method could be associated with considerable increases in the profitability of animal production, however, the whole area is poorly understood. The objective of this experiment was to enhance our understanding of the effect of flavour imprinting on the acceptability of solid food, and hence our ability to predict the diet selection and food intake of newly weaned animals.
A 36C1 peak has been found at about 37 ka BP in the Guliya ice core, drilled from the Qinghai-Tibetan Plateau. This peak is indicative of enhanced cosmogenic isotope production in the atmosphere, rather than a change in accumulation rate. Comparison with the records of 10Be and 36C1 in ice cores from Antarctica and Greenland indicates that peaks of the cosmogenic isotopes are global, and that they can be used as time markers for dating ice cores. Interestingly, the 37 ka BP global event coincided with a cold period.
In 1992, an American-Chinese expedition successfully recovered three ice cores (308.6, 93.2 and 34.5m) from the Guliya ice cap (summit 6710 m a.s.l) in the far western Kunlun on the Qinghai–Tibetan Plateau, China. Guliya resembles a “polar” icecap with 10 m, 200 m and basal temperatures of –15.6°, –5.9° and –2.1°C, respectively. The 308.6 m core to bedrock is the longest ice core retrieved from an elevation greater than 4000 m a.s.l. and provides the first ice-core history from the western side of the Qinghai Plateau. The Plateau experiences a pronounced annual precipitation cycle during which 70–80% of annual total precipitation falls in the summer monsoon season. This leads to a marked visible stratigraphy in the glaciers which allows accurate dating of the ice cores and reconstruction of the net mass accumulation.
This paper presents (1) the results of the geophysical program to determine ice thickness, ice flow and surface topography, (2) an assessment of net accumulation from stake measurements, snow pits and shallow core samples, and (3) the analyses of the upper 100 m of the 308.6 m core which provide a 1000 year history, including the ‘“Little Ice Age”, which is compared with Chinese historical records. Extended periods of positive accumulation on Guliya are closely contemporaneous with dry periods in eastern China. A trans-Pacific teleconnection is suggested by the strong temporal coherence between extended wet and dry phases on Guliya and on the Quelccaya ice cap, Peru.
Ice cores recently drilled to bedrock on the col of Huascarán (9°06′ S, 77°36′ W, 6047 m a.s.l.) offer the potential for a long, annually resolved climate record from tropical South America. This paper presents the record from 1950 to 1993 preserved in microparticle and nitrate concentrations and oxygen-isotopic ratios. Average monthly temperatures from a satellite-linked automatic weather station installed on nearby Hualcán in 1991 are presented. Annual temperatures from local high-altitude meteorological stations, along with the annual Huascarán isotopic record, show a warming trend over the last two decades. The marked preservation of the climate record in oxygen-isotopic ratios on Huascarán is absent at lower-elevation sites, which have been affected by the recent warming. This paper demonstrates the establishment of a time-scale for the Huascarán core, the preservation of the climatic signal with depth and the linkage of the ice-core “proxy-climate” parameters with measured climatic variations.
The first ice-core record of both the Holocene and Wisconsin/Würm Late Glacial Stage (LGS) from the subtropics has been extracted from three ice cores to bedrock from the Dunde ice cap on the north-central Qinghai-Tibetan Plateau. Ice thicknesses at the ice-cap summit average 138 m, the bedrock surface is relatively flat, surface and basal temperatures are −7.3 and −4.7°C, respectively and the ice cap exhibits radial flow away from the summit dome. These records reveal a major change in the climate of the plateau ∼10 000 years ago and suggest that LGS conditions were colder, wetter and dustier than Holocene conditions. This is inferred from the more negative δ18O ratios, increased dust content, decreased soluble aerosol concentrations, and reduced ice-crystal sizes, which characterize the LGS part of the cores. Total β radioactivity from shallow ice cores indicates that over the last 24 years the average accumulation rate has been ∼400 mm a−1 at the summit. The ice cores have been dated using a combination of annual layers in the insoluble dust and δ18O in the upper sections of core, visible dust layers which are annual, and ice-flow modeling. The oxygen-isotope record which serves as a temperature proxy indicates that the last 60 years have been the warmest in the entire record.
The quality and utility of the records of oxygen-isotopic abundances, dust concentrations and anionic concentrations preserved in the ice at Siple Station (75°55′ S, 84° 15′ W) are assessed from four shallow (20 m) cores. The combination of high accumulation (0.56 m a−1 w.e.) and low mean annual temperature (—24°C) preserves the prominent seasonal variations in δ18Ο which are very spatially coherent. Sulfate concentrations vary seasonally and, in conjunction with δ18Ο, will allow accurate dating of deeper cores from Siple Station. The concentrations of insoluble dust are the lowest measured in Antarctica, making Siple Station an excellent location to examine large increases in atmospheric tubidity.
The seasonal variations and annual fluxes of the anions are examined for the last two decades (AD 1966–85) with regard to probable sources. An unusually high sulfate flux in 1976 may reflect the February 1975 eruption of Mount Ngauruhoe, New Zealand. No annual signal in nitrate concentration is confirmed and no unusually high nitrate fluxes support the suggestion of nitrate production by large solar flares. However, nitrate flux is higher for the latter half of the 1970s and early 1980s, possibly reflecting the recent loss of stratospheric ozone.
Finally, comparison of the δ18O record with available surface-temperature data (AD 1957–85) reveals that multi-year trends along the western coast of the Antarctic Peninsula are recorded at Siple. More importantly, comparison with areally weighted temperature reconstructions suggests that the δ18Ο record may reflect larger-scale, persistent trends in the high southern latitudes. The strong spatial coherence of the preserved records, the potential for accurate dating, and possible relevance to larger-scale processes make Siple Station an excellent site for paleoenvironmental reconstruction from ice cores.
Both maternal 25-hydroxyvitamin D (25(OH)D) concentrations during pregnancy and
placental amino acid transporter gene expression have been associated with
development of the offspring in terms of body composition and bone structure.
Several amino acid transporter genes have vitamin D response elements in their
promoters suggesting the possible linkage of these two mechanisms. We aimed to
establish whether maternal 25(OH)D and vitamin D-binding protein (VDBP) levels
relate to expression of placental amino acid transporters. RNA was extracted
from 102 placental samples collected in the Southampton Women's Survey,
and gene expression was analysed using quantitative real-time PCR. Gene
expression data were normalised to the geometric mean of three housekeeping
genes, and related to maternal factors and childhood body composition. Maternal
serum 25(OH)D and VDBP levels were measured by radioimmunoassay. Maternal
25(OH)D and VDBP levels were positively associated with placental expression of
specific genes involved in amino acid transport. Maternal 25(OH)D and VDBP
concentrations were correlated with the expression of specific placental amino
acid transporters, and thus may be involved in the regulation of amino acid
transfer to the fetus. The positive correlation of VDBP levels and placental
transporter expression suggests that delivery of vitamin D to the placenta may
be important. This exploratory study identifies placental amino acid
transporters which may be altered in response to modifiable maternal factors and
provides a basis for further studies.