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Historically, the development of XRF spectrometers has followed 2 main paths which are characterized by the means of spectral resolution they use. Those employing diffraction crystals and Braggs law to disperse the X-ray wavelengths are known as wavelength dispersive (WDX), whilst those usinq only the energy resolution of the detector, as enerqy dispersive (EDX). In the past these two have not normally been directly compared, because the WDX systems have always been the more expensive.
NHS England has commissioned intensity-modulated radiotherapy for head and neck cancers from Newcastle hospitals for patients in North Cumbria. This study assessed whether travel distances affected the decision to travel to Newcastle (to receive intensity-modulated radiotherapy) or Carlisle (to receive conformal radiotherapy).
All patients for whom the multidisciplinary team recommended intensity-modulated radiotherapy between December 2013 and January 2016 were included. Index of multiple deprivation scores and travel distances were calculated. Patients were also asked why they chose their treating centre.
Sixty-nine patients were included in this study. There were no significant differences in travel distance (p = 0.53) or index of multiple deprivation scores (p = 0.47) between patients opting for treatment in Carlisle or Newcastle. However, 29 of the 33 patients gave travel distance as their main reason for not travelling for treatment.
Quantitatively, travel distance and deprivation does not impact on whether patients accept intensity-modulated radiotherapy. However, patients say distance is a major barrier for access. Future research should explore how to reduce this.
From June 15 to 28, 1991 the Compton Gamma-Ray Observatory (CGRO) observed the radio-loud quasar 3C 273. All four CGRO instruments detected radiation from this quasar in their relevant energy range (from 20 keV to 5 GeV). Simultaneous and quasi-simultaneous observations (spanning the time period May 27 – July 25, 1991) by instruments sensitive at other wavelengths have also been obtained. The data from all these observations spanning the frequency range from ∼ 109 Hz to ∼ 1026 Hz were collected and analysed. The resulting energy-density spectrum is shown in the figure below. It shows two maxima, one in the UV, another one at low-energy γ-rays which have nearly the same strength (the corresponding luminosities per decade of frequency for H0 = 60(km/s)/Mpc are 3.2·1046 erg/s and 2.7·1046 erg/s, respectively). A break of the spectrum at low-energy γ-rays is evident. From a detailed analysis a break energy of (2±1.5) MeV could be derived corresponding to a frequency of (4.8±3.6)·1020 Hz. The observed spectral break between X- and γ-rays is ∼ 0.8, much higher than the value of 0.5 predicted by some models. A more detailed paper on this topic is in preparation (Lichti et al.).
Since the previous edition of these guidelines, significant changes have taken place in the training and assessment of surgeons and oncologists who treat patients with head and neck cancer. For those intending to become head and neck surgeons, a fellowship in head and neck surgery is virtually mandatory. This paper summarises the current career structure to specialise in head and neck oncology and surgery in the UK.
• Trainees applying for head and neck surgical oncology consultant posts should have completed additional training in the subspecialty.
In order to investigate and demonstrate objective modelling of proteins as a basis for drug design, we have sought to model several proteins in particularly persuasive circumstances. This is either (a) by filing the results of the model with an independent institution prior to X-ray determination of their structure, or (b) by using wholly automatic, general and reproducible methods, or (c) most often by both. Results suggest the ability to predict the core of the protein to an accuracy of about 1 Å rms deviation between predicted and experimental all-atom coordinates, and of surface loops in the range 1-4 Å rms deviation. Although the upper end of the latter scale seems disturbing, it turns out that many of the surface loops show such large variations for the same protein as studied by different crystallographic groups, particularly when no common protein is used as a starting point for refinement in both cases. Recognising the dynamic nature of some loops on enzymes, and including in the calculation the ability to handle dynamics over long timescales, allows analysis and refinement of enzyme inhibitors as pharmaceuticals. Here we analyse these aspects, particularly by reference to X-ray crystallography data.
Epitaxial growth of oxide heterostructures, which may be utilized in spin valve applications, has been demonstrated. The heterostructures consist of two ferromagnetic layers separated by a nonmagnetic metallic interlayer. The ferromagnetic material used is the manganese perovskite oxide, La0.7Sr0.3MnO3, while the metallic oxide interlayer is La0.5Sr0.5CoO3. X-ray diffraction spectra demonstrate the high structural quality of the heterostructures. The magnetization of the heterostructure as a function of magnetic field measured at room temperature yields a double hysteresis loop that is characteristic of this type of spin valve structure. The behavior of this double hysteresis loop is also examined as a function of the metallic interlayer thickness.
Large food portions may be facilitating excess energy intake (EI) and adiposity among adults. The present study aimed to assess the extent to which EI and amounts of foods consumed are influenced by the availability of different-sized food portions. A randomised within-subject cross-over, fully residential design was used, where forty-three (twenty-one men and twenty-two women) normal-weight and overweight adults were randomly allocated to two separate 4 d periods where they were presented with either ‘standard’ or ‘large’ food portions of the same foods and beverages. The main outcome measures were the amount of food (g) and EI (MJ) consumed throughout each study period. Mean EI over 4 d was significantly higher on the large portion condition compared with the standard condition in the total group (59·1 (sd 6·6) v. 52·2 (sd 14·3) MJ; P = 0·020); men and women increased their EI by 17 % (10 (sd 6·5) MJ; P < 0·001) and 10 % (4 (sd 6·5) MJ; P = 0·005) respectively when served the large food portions relative to the standard food portions. The increased intakes were sustained over the 4 d in the large portion condition with little evidence of down-regulation of EI and food intake being made by subjects. Increased food portion size resulted in significant and sustained increases in EI in men and women over 4 d under fully residential conditions. The availability and consumption of larger portions of food may be a significant factor contributing to excess EI and adiposity.
Pre-weaning piglet mortality is currently 11.8% of piglets born alive in indoor units (MLC, 2005) and is a major welfare concern and a continuing production problem within the pig industry. The farrowing crate was implemented with some success to decrease the amount of crushing of piglets (Edwards & Fraser, 1997). However, this system is restrictive, limits the behaviour and compromises the welfare of the sow (Jarvis et al., 2001). There is growing pressure to abolish this technology in favour of less restrictive systems. It is therefore vital to identify behavioural and physiological characteristics relating to piglet survival, which can then be influential in alternative systems. Important factors in relation to piglet survival include birth weight, birth order, and adequate thermoregulation (Tuchscherer et al. 2001). The aim of this study was to identify additional behavioural and physiological indicators, which could predict piglet survival.
To evaluate the emergence of resistance of Pseudomonas aeruginosa and Acinetobacter species to imipenem, ciprofloxacin, or both after the use of these drugs and to compare resistant with susceptible isolates by molecular typing.
Burn intensive care unit (ICU) with 4 beds in a tertiary-care university hospital.
During 16 months, surveillance cultures were performed for all patients admitted to the ICU. Demographic information was obtained for each patient. Molecular typing was done by pulsed-field gel electrophoresis using restriction enzymes for 71 isolates of P. aeruginosa and Acinetobacter species.
Thirty-four patients were admitted and 22 were colonized by susceptible P. aeruginosa or Acinetobacter species before they used the antimicrobials. Nine (41%) of these patients had a resistant isolate after antimicrobial use: 5 had used imipenem alone, 1 had used ciprofloxacin, and 3 had used both drugs. The interval between isolation of the susceptible and resistant isolates ranged from 4 to 25 days, but was 10 or more days for 6 patients. Molecular typing revealed that susceptible and resistant isolates from each patient were different and that although there were no predominant clones among susceptible isolates, there was a predominant clone among resistant isolates of P. aeruginosa and of Acinetobacter.
Resistance was not due to the acquisition of resistance mechanisms by a previously susceptible strain, but rather to cross-transmission. Although various measures involving antimicrobial use have received great attention, it would seem that practices to prevent cross-transmission are more important in controlling resistance.
Studies of food habits and dietary intakes face a number of unique respondent and observer considerations at different stages from early childhood to late adolescence. Despite this, intakes have often been reported as if valid, and the interpretation of links between intake and health has been based, often erroneously, on the assumption of validity. However, validation studies of energy intake data have led to the widespread recognition that much of the dietary data on children and adolescents is prone to reporting error, mostly through under-reporting. Reporting error is influenced by body weight status and does not occur systematically across different age groups or different dietary survey techniques. It appears that the available methods for assessing the dietary intakes of children are, at best, able to provide unbiased estimates of energy intake only at the group level, while the food intake data of most adolescents are particularly prone to reporting error at both the group and the individual level. Moreover, evidence for the existence of subject-specific responding in dietary assessments challenges the assumption that repeated measurements of dietary intake will eventually obtain valid data. Only limited progress has been made in understanding the variables associated with misreporting in these age groups, the associated biases in estimating nutrient intakes and the most appropriate way to interpret unrepresentative dietary data. Until these issues are better understood, researchers should exercise considerable caution when evaluating all such data.
An extension of the previously proposed model of Mg metabolism (Robson et al. 1997) has been developed to consider the transactions of Mg that are associated with cerebrospinal fluid (CSF) and bone. The representation of the CSF as a single Mg compartment with uptake from the plasma described by Michaelis–Menten kinetics gives very good agreement with published experiments. Analysis of the available information on resorption of Mg from adult bone indicates that this process makes a negligible contribution to Mg homeostasis and can be omitted from the model.
The accurate measurement of physical activity is fraught with problems in adults, but more especially in children because they have more complex and multi-dimensional activity patterns. In addition, the results of different studies are often difficult to interpret and compare, because of the diversity of methodological approaches, differences in data analysis and reporting, and the adoption of varying definitions of what constitutes an appropriate level of activity. Furthermore, inactivity is seldom quantified directly. Although there exists an extensive literature documenting the health benefits of regular physical activity in adults, activity-health relationships in children are not clear-cut. Current recommendations reinforce the concept of health-related activity, accumulating 30 min moderate-intensity exercise on at least 5 d/week (adults) and 1 h moderate-intensity exercise/d (children). Evidence suggests a high prevalence of inactivity in adults, but whether or not inactivity is increasing cannot be assessed currently. Similarly, no definite conclusions are justified about either the levels of physical activity of children, or whether these are sufficient to maintain and promote health. Data to support the belief that activity levels in childhood track into adulthood are weak. Inactivity is associated with an increased risk of weight gain and obesity, but causality remains to be established. In children there is strong evidence to demonstrate a dose-response relationship between the prevalence and incidence of obesity and time spent viewing television. Future research should focus on refining methodology for physical activity assessment to make it more sensitive to the different dimensions and contexts of activity in different age-groups.
This study evaluated the tracking of energy and nutrient intakes, assessed by diet history, in a random sample of adolescents (boys n 225, girls n 230) at baseline (age 12 years), and subsequently at age 15 years. Median energy (MJ/d) and macronutrient (g/d) intakes increased significantly (all P<0·001) with increasing age in the boys. The girls' reported energy intake (MJ/d) remained stable over time, despite significant increases in BMI, weight and % body fat. Age-related changes in the girls' macronutrient intakes were inconsistent. When expressed in terms of nutrient density, the diets of both sexes became significantly richer, over time, in total folate (both sexes, P<0·01), but poorer in Ca (boys P<0·01, girls P<0·001) and riboflavin (both sexes P<0·001). Vitamin B6 (P<0·001) and Fe (P<0·05) densities increased in the boys, while the thiamin density of the girls' diets decreased (P<0·001). Tracking, defined as maintenance of rank over time, was summarised using weighted kappa statistics (κ). There were some significant changes in intakes at the group level; however, tracking of energy and nutrients in both sexes was only poor to fair (κ<0·40), indicating substantial drift of individuals between classes of intake over time. Particularly poor tracking was evident for % energy from sugars (κ 0·09) and total fat (κ 0·09) in the girls' diets. In conclusion, the poor to fair tracking observed in this cohort suggests that individual dietary patterns exhibited at 12 years of age are unlikely to be predictive of energy and nutrient intake at age 15 years.
When children and adolescents are the target population in dietary surveys many different respondent and observer considerations surface. The cognitive abilities required to self-report food intake include an adequately developed concept of time, a good memory and attention span, and a knowledge of the names of foods. From the age of 8 years there is a rapid increase in the ability of children to self-report food intake. However, while cognitive abilities should be fully developed by adolescence, issues of motivation and body image may hinder willingness to report. Ten validation studies of energy intake data have demonstrated that mis-reporting, usually in the direction of under-reporting, is likely. Patterns of under-reporting vary with age, and are influenced by weight status and the dietary survey method used. Furthermore, evidence for the existence of subject-specific responding in dietary assessment challenges the assumption that repeated measurements of dietary intake will eventually obtain valid data. Unfortunately, the ability to detect mis-reporters, by comparison with presumed energy requirements, is limited unless detailed activity information is available to allow the energy intake of each subject to be evaluated individually. In addition, high variability in nutrient intakes implies that, if intakes are valid, prolonged dietary recording will be required to rank children correctly for distribution analysis. Future research should focus on refining dietary survey methods to make them more sensitive to different ages and cognitive abilities. The development of improved techniques for identification of mis-reporters and investigation of the issue of differential reporting of foods should also be given priority.
A model of Mg metabolism in sheep is proposed. It is based on standard Michaelis-Menten enzyme kinetics to describe the transport of Mg across the rumen wall and passive diffusion to describe the absorption of Mg in the hindgut. Factors known to have an effect on Mg metabolism in farm animals, namely the concentrations of K and Mg in the diet, and the physico-chemical conditions within the rumen as determined by the type of diet, are incorporated into the model. Consideration of the rumen as the only site of Mg absorption provided an inadequate mechanistic description of Mg metabolism in sheep. To ensure compatibility between predicted Mg absorption and recent independent data sets for Mg balances, it was necessary to include in the model aspects of Mg absorption that operate in the hindgut. The results from this model suggest that there is a need for a series of experiments to determine the important aspects of Mg transport in the hindgut of sheep. Mechanisms of homeostasis are discussed.
Sixteen 2-year old female sheep were fitted with ruminal
and duodenal cannulae at Johnstone
Memorial Laboratory, Lincoln University during 1989–90.
They were offered, at 2 hourly intervals,
a pelleted concentrate diet (900 g/day) and chaffed lucerne hay
(100 g/day). In a split-plot experiment
they were infused, intraruminally and at four rates, with potassium
(providing 16, 26, 36 or 46 g K/kg
food DM/day) and magnesium (providing 1·3, 1·8, 2·3
or 3·1 g Mg/kg food DM/day) within a Latin
square design and with the liquid and solid phase markers
51chromium EDTA and 141cerium chloride.
Net absorption of Mg before and after the duodenum was estimated
from dietary intake, duodenal flow and urinary and faecal excretion of Mg.
Increasing K intake resulted in a decline in net absorption of Mg from
the entire digestive tract,
supporting data in the literature. Increasing K intake from 16 to 46 g/kg
DM decreased urinary Mg
excretion by between 0·14 and 0·30 g/day, the extent of which was
independent of the level of Mg
intake. At high K intake Mg absorption from the rumen was reduced,
the amount absorbed ranging
from 0·07 g Mg/day at intakes of 1·3 g Mg/day and
46 g K/kg DM/day to 0·66 g Mg/day at intakes
of 3·1 g Mg/day and 16 g K/kg DM/day. However, at high
K intake, and when Mg absorption from
the rumen was reduced, net Mg absorption from sites distal to
the rumen was increased to an extent
which suggested compensatory absorption. Increase in K intake was
associated with a consistent
reduction in plasma Mg concentration which was independent of Mg
intake. Increases in Mg intake
resulted in increases in Mg absorption and plasma Mg concentration
at all rates of K intake in direct
proportion to rate of intake. The reduction in Mg absorption from
the rumen at high K intake was
associated with an increase (0·3 units) in pH of rumen digesta.
Rumen and caecal digesta were collected, under anaesthetic, from
eight sheep offered either hay,
pelleted concentrate or pasture at the Johnston Memorial Laboratory,
Lincoln University during
1991. Subsamples of digesta were incubated at 39°C for 1 h after adjustment
of pH within the range
0·5–12 by the addition of H2SO4 or
NaOH. The samples were centrifuged at 30000 g for 30 min and
magnesium (Mg) concentration measured in the 30000 g supernatant
fraction and in total digesta to
assess Mg solubility. In rumen digesta, Mg solubility declined from
0·86 at pH 5 to 0·30 at pH 7 and
differences in response between diets were small. Magnesium solubility
in caecal digesta was generally
higher than in ruminal digesta, and particularly at pH values >6.
At pH 7 the difference was twofold.
Moreover, differences were observed between diets in the rate of
decline in solubility in caecal digesta
with increasing pH. At pH 5, 0·90 of Mg from hay and
concentrate diets was soluble compared with
only 0·8 for pasture. At pH 7, Mg solubility in caecal
digesta from hay and concentrate-fed animals
was almost double that from pasture-fed animals (0·64 and
0·62 v. 0·36, respectively). The implications
of the findings for Mg homoeostasis in ruminants are discussed.