University of Bedfordshire

About: University of Bedfordshire is a education organization based out in Luton, Bedford, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 3860 authors who have published 6079 publications receiving 143448 citations. The organization is also known as: University of Luton.

New Methods for Measurement of Complex Permittivity up to 13 GHz and their Application to the Study of Dielectric Relaxation of Polar Liquids Including Aqueous solutions

Abstract: High frequency dielectric measurements, until recently the exclusive prerogative of point-by-point frequency domain methods, can now be made with very reasonable precision in the time domain. These novel methods which are an extension of the earlier reported Time Domain Reflectometry technique yield dielectric information over a range equivalent in frequency to about 10 MHz to 13 GHz. The theoretical basis of these methods is given and their accuracy demonstrated by reference to measurements on water and ethanol. An example of their application to aqueous systems is also given. Hochfrequenzmessungen an Dielektrika, die bisher nur durch “Punkt-fur-Punkt”-Methoden im Frequenzgebiet (frequency domain) ausfuhrbar waren, konnen jetzt mit guter Prazision im Zeitgebiet (time domain) ausgefuhrt werden. Diese neuen Methoden, die eine Verbesserung fruher berichteter Zeitgebiet-Reflektionsmethoden darstellen, gestatten die Ermittlung dielektrischen Verhaltens fur einen Frequenzbereich von etwa 10 MHz bis 13 GHz. Die theoretische Basis dieser Methode wird erlautert und ihre Prazision dargelegt durch Messungen an Wasser und an Athanol. Ein Beispiel ihrer Anwendung auf wasserenthaltende Systeme wird vorgelegt.

A critical evaluation of genomic control methods for genetic association studies.

Abstract: Population stratification is an important potential confounder of genetic case-control association studies For replication studies, limited availability of samples may lead to imbalanced sampling from heterogeneous populations Genomic control (GC) can be used to correct chi(2) test statistics which are presumed to be inflated by a factor lambda; this may be estimated by a summary chi(2) value (lambda(median) or lambda(mean)) from a set of unlinked markers Many studies applying GC methods have used fewer than 50 unlinked markers and an important question is whether this can adequately correct for population stratification We assess the behavior of GC methods in imbalanced case-control studies using simulation SNPs are sampled from two subpopulations with intra-continental levels of FST (< or =0005) and sampling schemata ranging from balanced to completely imbalanced between subpopulations The sampling properties of lambda(median) and lambda(mean) are explored using 6-1,600 unlinked markers to estimate Type 1 error and power empirically GC corrections based on the chi(2)-distribution (GC(median) or GC(mean)) can be anti-conservative even when more than 100 single nucleotide polymorphisms (SNPs) are genotyped and realistic levels of population stratification exist The GCF procedure performs well over a wider range of conditions, only becoming anti-conservative at low levels of alpha and with fewer than 25 SNPs genotyped A substantial loss of power can arise when population stratification is present, but this is largely independent of the number of SNPs used A literature survey shows that most studies applying GC have used GC(median) or GC(mean), rather than GCF, which is the most appropriate GC correction method

Effort–reward imbalance and overcommitment in UK academics: implications for mental health, satisfaction and retention

Abstract: This study utilises the effort–reward imbalance (ERI) model of job stress to predict several indices of well-being in academics in the UK: mental ill health, job satisfaction and leaving intentions. This model posits that (a) employees who believe that their efforts are not counterbalanced by sufficient rewards will experience impaired well-being and (b) feelings of ERI are more frequent and damaging in employees who are overcommitted to the job. A sample of 649 academic employees working in UK higher education institutions completed validated measures. Findings showed that academics who found their work more demanding, who perceived greater rewards and who were less overcommitted typically reported poorer well-being across all measures. Rewards related to esteem/support and financial/status appeared to be particularly important in protecting academics from the negative impact of work-related efforts. Potential interventions are discussed that draw on the ERI framework to improve mental health, sa...

Sirtuin 1 regulates skeletal myoblast survival and enhances differentiation in the presence of resveratrol

Abstract: Sirtuin 1 also known as NAD-dependent deacetylase sirtuin 1, is a protein that in humans is encoded by the Sirt1 gene. Sirt1 is an enzyme that deacetylates proteins that contribute to cellular regulation and is a key regulator of cell defenses and survival in response to stress. Deletion of Sirt1 abolishes the increase in lifespan induced by calorie restriction or sublethal cytokine stress, indicating that Sirt1 promotes longevity and survival. We have demonstrated that administration of a sublethal dose of tumour necrosis factor-α (TNF-α; 1.25 ng ml−1) inhibits myotube formation, and co-incubation with insulin-like growth factor I (IGF-I; 1.5 ng ml−1) facilitates C2 myoblast death rather than rescuing differentiation. A higher dose of TNF-α (10 ng ml−1) resulted in significant apoptosis, which was rescued by IGF-I (1.5 ng ml−1; 50% rescue; P < 0.05). We aimed to investigate the role of Sirt1 in the conflicting roles of IGF-I. Quantitative real-time PCR revealed that Sirt1 expression was elevated in myoblasts following incubation of 10 ng ml−1 TNF-α or 1.25 ng ml−1 TNF-α plus IGF-I (fivefold and 7.2-fold increases versus control, respectively; P < 0.05). A dose of 10 ng ml−1 TNF-α induced ∼21 ± 0.7% apoptosis, which was reduced (∼50%; P < 0.05) when administered with IGF-I. Likewise, Sirt1 expression was elevated following 10 ng ml−1 TNF-α administration, but was reduced (∼30%; P < 0.05) in the presence of IGF-I. C2C12 myoblasts, a subclone of the C2 cell line produced for their differentiation potential and used to examine intrinsic ageing, unlike C2 cells, do not die in the presence of TNF-α and do not upregulate Sirt1. As conditions that induced the greatest myoblast stress/damage resulted in elevated Sirt1 expression, we investigated the effects of Sirt1 gene silencing. Treatment with 10 ng ml−1 TNF-α or co-incubation with 1.25 ng ml−1 TNF-α and 1.5 ng ml−1 IGF-I resulted in apoptosis (20.33 ± 2.08 and 19 ± 2.65%, respectively), which was increased when myoblasts were pretreated with Sirt1 small interfering RNA (31 ± 2.65 and 27.33 ± 2.52%, respectively; P < 0.05) and was reduced (14.33 ± 3.05%, P < 0.05 and 12.78 ± 4.52%, P= 0.054) by resveratrol, which also significantly rescued the block on differentiation. In conclusion, Sirt1 expression increases in conditons of stress, potentially serving to reduce or dampen myoblast death.

Co-ordinate regulation of sterol biosynthesis enzyme activity during accumulation of sterols in developing rape and tobacco seed.

Abstract: The activities of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, sterol methyl transferase 1 and sterol acyltransferase, key enzymes involved in phytosterol biosynthesis were shown to be co-ordinately regulated during oilseed rape (Brassica napus L) and tobacco (Nicotiana tabacum L) seed development In both plants, enzyme activities were low during the initial stages of seed development, increasing towards mid-maturation where they remained stable for a time, before declining rapidly as the oilseeds reached maturity During seed development, the level of total sterols increased 12-fold in tobacco and 9-fold in rape, primarily due to an increase in steryl ester production In both seed tissues, stages of maximum enzyme activity coincided with periods of high rates of sterol production, indicating developmental regulation of the enzymes to be responsible for the increases in the sterol content observed during seed development Consistent with previous studies the data presented suggest that sterol biosynthesis is regulated by two key steps, although there may be others The first is the regulation of carbon flux into the isoprenoid pathway to cycloartenol The second is the flux from cycloartenol to Δ5-end-product sterols The implications of the results in terms of enhancing seed sterol levels by genetic modification are also discussed