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A series of 14C determinations have been obtained on hair samples principally from Holocene contexts that have been variously pretreated to examine different means of removing potential contamination. SEM photomicrographs have documented hair surfaces before and after different pretreatments. Amino-acid composition, C/N ratios and δ13C values have been obtained to biochemically characterize these samples and provide baseline data for future comparisons with less well-preserved samples. Our data support the view that appropriately pretreated hair samples can provide accurate 14C age determinations.
Modern bone contains ca 25% protein material, most of which is collagen. Amino acids separated from collagen isolated from bone are suitable for 14C dating of fossil bone, but attempts to carry out this procedure on bones seriously depleted in protein can yield erroneous 14C dates. Amino-acid analysis of fossil bone gives quantitative information on the degree of preservation of its organic component. Also, the relative abundance of the amino-acid components reveal the degree to which the collagen-like pattern has been altered. Alteration may be caused by addition of extraneous material. A 1mg sample of bone material is sufficient for this preliminary analysis. We have developed a series of acceptance criteria for whether a particular specimen is likely to yield the correct 14C age. 14C dating of fossil bones not seriously depleted in protein is a straightforward procedure and yields reliable dates.
Radiocarbon determinations have been obtained on γ-carboxyglutamic acid [Gla] and α-carboxyglycine (aminomalonate) [Am] as well as acid- and base-hydrolyzed total amino acids isolated from a series of fossil bones. As far as we are aware, Am has not been reported previously in fossil bone and neither Gla nor Am 14C values have been measured previously. Interest in Gla, an amino acid found in the non-collagen proteins osteocalcin and matrix Gla-protein (MGP), proceeds from the suggestion that it may be preferentially retained and more resistant to diagenetic contamination affecting 14C values in bones exhibiting low and trace amounts of collagen. Our data do not support these suggestions. The suite of bones examined showed a general tendency for total amino acid and Gla concentrations to decrease in concert. Even for bones retaining significant amounts of collagen, Gla (and Am extracts) can yield 14C values discordant with their expected age and with 14C values obtained on total amino-acid fractions isolated from the same bone sample.
Major discordances between AMS 14C- and aspartic acid racemization (AAR)-deduced age estimates on bone samples have led to an examination of factors other than time and temperature that can fundamentally influence the degree of racemization observed in fossil bone. Our studies support previous suggestions that for many bone samples the chemical state of amino acids must be routinely considered if AAR-deduced age estimates are to be used to make meaningful chronologic inferences.
In studies using magnetic resonance imaging (MRI), some have reported specific brain structure–function relationships among first-episode psychosis (FEP) patients, but findings are inconsistent. We aimed to localize the brain regions where cortical thickness (CTh) and surface area (cortical area; CA) relate to neurocognition, by performing an MRI on participants and measuring their neurocognitive performance using the Cambridge Neuropsychological Test Automated Battery (CANTAB), in order to investigate any significant differences between FEP patients and control subjects (CS).
Exploration of potential correlations between specific cognitive functions and brain structure was performed using CANTAB computer-based neurocognitive testing and a vertex-by-vertex whole-brain MRI analysis of 63 FEP patients and 30 CS.
Significant correlations were found between cortical parameters in the frontal, temporal, cingular and occipital brain regions and performance in set-shifting, working memory manipulation, strategy usage and sustained attention tests. These correlations were significantly dissimilar between FEP patients and CS.
Significant correlations between CTh and CA with neurocognitive performance were localized in brain areas known to be involved in cognition. The results also suggested a disrupted structure–function relationship in FEP patients compared with CS.
1.1 This paper owes its existence on two counts to the late Jim Souness whose term of office as President of the Faculty coincided with the bulk of our research. Firstly, as President, he encouraged Faculty research groups to be active and to produce material worthy of sessional papers. More directly it was the late President who funnelled our general investigations of life office management (which had continued after the Group's 1987 sessional paper) towards the issue of demutualisation.
There have been several notable demutualisations of life offices in recent years, yet there is little published research in the UK other than case studies into the actuarial issues which these restructurings raise for the profession. Furthermore much of what has been published pertains to overseas regimes not subject to UK-style regulation. However at the time of writing we are aware that another paper (reference 20) was being written concurrently, and it relates specifically to the UK.
We report on the integration of erbium doped silicon-rich oxide into
toroidal microcavities. Coupling of erbium ions to microtorus whispering
gallery modes is evidenced at room temperature under excitation of silicon
clusters. The fabrication process is controlled so that no luminescence
quenching occurs during the silica melting step. The spatial and spectral
distributions of outgoing light are investigated thanks to independent
excitation and collection optics.
Recently, several investigators have reported an association between influenza epidemics and increased birth rates of ‘preschizophrenic’ individuals some four to six months later. Here we examine whether maternal exposure to other infectious diseases can also predispose the foetus to later schizophrenia.
Two independent sets of dates of birth of first admission schizophrenic patients, born between 1938 and 1965 in England and Wales, were obtained from the Mental Health Enquiry in England and Wales. Data on the number of deaths per month from 16 infectious diseases between 1937 and 1965 in England and Wales were also collected. We used a Poisson regression model to examine the relationship between deaths from infectious diseases and schizophrenic births.
In the two separate data sets, increased national deaths from bronchopneumonia preceded, by three and five months respectively, increased numbers of schizophrenic births. We did not find any other significant associations between schizophrenic births and any of the other 15 infectious diseases.
The association between deaths from bronchopneumonia and increased schizophrenic births some months later may be a reflection of the fact that bronchopneumonia deaths increase markedly during influenza epidemics.
The epidemiological evidence that the offspring of women exposed to influenza in pregnancy are at increased risk of schizophrenia is conflicting. In an attempt to clarify the issue we explored the relationship between the monthly incidence of influenza (and measles) in the general population and the distribution of birth dates of three large series of schizophrenic patients - 16 960 Scottish patients born in 1932–60; 22 021 English patients born in 1921–60; and 18 723 Danish patients born in 1911–65. Exposure to the 1957 epidemic of A2 influenza in midpregnancy was associated with an increased incidence of schizophrenia, at least in females, in all three data sets. We also confirmed the previous report of a statistically significant long-term relationship between patients' birth dates and outbreaks of influenza in the English series, with time lags of - 2 and - 3 months (the sixth and seventh months of pregnancy). Despite several other negative studies by ourselves and others we conclude that these relationships are probably both genuine and causal; and that maternal influenza during the middle third of intrauterine development, or something closely associated with it, is implicated in the aetiology of some cases of schizophrenia.
In two series of psychiatric patients (numbering about 6,000 and 2,000 respectively), the mean age of the mothers at the time of the patients' birth was found to be very significantly above expectation from the general population, and this was so for each of the major diagnostic groups. In the second series, the age of the fathers was also found to be very significantly above that expected from a sample survey of the general population, and this was so for each diagnostic group. Fathers' age was raised more than mothers', and was highest for schizophrenia. The raised parental age could not be explained in terms of the patient's year of birth or his father's social class. The raised mothers' age could largely be accounted for by regression on the raised fathers' age. The present findings, and those of previous studies, seem best explained on the hypothesis of a constitutional parental trait leading to delayed marriage.
Parental age (at patient's birth) and birth order were studied in 623 male and 89 female patients diagnosed as homosexual, who were born in England and Wales and first attended the Maudsley Hospital between the years 1961–1975. For male patients, mean parental ages were significantly higher than expectation, and mean birth order was significantly later. Regression analysis indicated that the raised fathers' age was probably of more aetiological importance than the raised mothers' age. The results confirm those of previous studies. The female patients did not show a raised parental age or late birth order.
Except for the year 1931, no information is available on age at paternity in England and Wales before 1961. But such information is needed to determine the aetiological significance of raised maternal age, for example that which has been reported for several types of psychiatric disorder. Parental age at the birth of a respondent was studied in a survey of 2000 persons forming a quota sample of the adult population of England and Wales. Checks against the available national statistics suggest the findings for age at paternity can be accepted with some confidence.
The Humean tradition claims to show that the direct perception of causal power is in principle impossible. One argument for this conclusion is very simple: One cannot perceive what is not there; ‘causal power’ entails ‘necessary connection’; there are no necessary connections between matters of fact; therefore one cannot perceive causal power. The heart of this argument, of course, and the backbone of the Humean tradition, is that there are no necessary connections between matters of fact. This contention is supported by the familiar Humean dialectic. If there were a necessary connection of any kind between C and E, then the conjunction of C · ˜ E would be self-contradictory. However, all events are complete in themselves and never alone require that any other event will or must result from them. It is very strange to think of water freezing when heated or air pressure decreasing with depth, but no matter how foreign these conceptions may seem there is nothing self-contradictory about them. Since the assertion of C · ˜ E is never self-contradictory, it follows that there can be no necessary connection, logical or “causal”, between them, and hence there is no causal power that we could directly perceive.
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