Book chapters will be unavailable on Saturday 24th August between 8am-12pm BST. This is for essential maintenance which will provide improved performance going forwards. Please accept our apologies for any inconvenience caused.
To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural–geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.
X-ray fluorescence spectroscopy has been in use since the early days of the twentieth century, when Moseley confirmed the order of the chemical periodic table. However, fluorescence spectroscopy until recently has depended on diffraction methods to obtain sufficient resolution. Intrinsic resolution of ionization chambers, scintillation detectors, and proportional counters is inadequate for discrimination o f lines due to adjacent elements of low atomic number. The advent o f solid-state detectors, especially those using lithium-compensated silicon and low-noise electronics, has recently brought intrinsic energy resolution to the point where lines from adjacent elements as light as carbon and nitrogen can be resolved in theory; and detection of K radiation from elements as light as sodium is practical. Thus the solution to the long-standing problem of an adequate detector is at hand, and energy-dispersive spectrometers are now feasible.
Over the past 25 years, numerous studies utilizing both X-ray diffraction (XRE) and differential scanning calorimetry (DSC) have been reported In the literature. Generally, conventional high-temperature X-ray data identifies solid-state transitions, then attempts to correlate them with thermal events observed by the calorimeter. Since changes occur in the sample during studies such as these, separate portions of the sample must be used for XRD and DSC experiments. When comparing results of the two experiments, questions arise concerning sample homogeniety as well as temperature and environmental differences. In fact, no conventional high-temperature X-ray diffraction instrument can give the precise control over temperature and heating rate available with a DSC, The problems of sample inhomogeneltles and Instrumental differences could be avoided if X-ray diffraction and DSC could be performed simultaneously on one sample.
Fundamental parameters calculations are used for the analysis of europium in the concentration range of 0.1 WT% to 30.0 WT% in the oxidic catalyst supports alumina, calcia, magnesia lanthania, and thoria. The precision and accuracy of this method is dependent on how the sample matrix is defined in the fundamental parameters program and the number and concentration of the standards used. Results comparable to the multiple regression method are obtained when the matrix stoichiometry is defined as Eu2O3 and the catalyst oxide (i.e. Al2O3 etc). It is also necessary to use standards which bracket the europium concentration in the samples. When these conditions are met, the results are comparable to those obtained from a ten point multiple regression calibration curve but with a considerable saving of standard preparation time. The precision is better than ±2% relative. The % relative difference between the fundamental parameters and multiple regression results is also 2%. Data is presented which illustrates the effect of defining the sample stoichiometry in the XRF11 computer program.