University College Cork

About: University College Cork is a education organization based out in Cork, Ireland. It is known for research contribution in the topics: Population & Irish. The organization has 12056 authors who have published 28452 publications receiving 958414 citations. The organization is also known as: Coláiste na hOllscoile Corcaigh & National University of Ireland, Cork.

Maternal body mass index, gestational weight gain and the risk of overweight and obesity across childhood: An individual participant data meta-analysis

Abstract: Background: Maternal obesity and excessive gestational weight gain may have persistent effects on offspring fat development. However, it remains unclear whether these risks differ by severity of obesity, and whether these effects are restricted to the extremes of maternal body mass index (BMI) and gestational weight gain. We aimed to assess the separate and combined associations of maternal BMI and gestational weight gain with the risk of overweight/obesity throughout childhood, and their population impact. Methods and Findings: We conducted an individual participant data meta-analysis of data from 162,129 mothers and children from 37 pregnancy and birth cohort studies from Europe, North-America and Australia. We assessed the individual and combined associations of maternal pre-pregnancy BMI and gestational weight gain, both in clinical categories and across their full ranges with the risks of overweight/obesity in early- (2.0-5.0 years), mid- (5.0-10.0 years) and late childhood (10.0-18.0 years), using multilevel binary logistic regression models with a random intercept at cohort level adjusted for maternal socio-demographic and life style related characteristics. We observed that a higher maternal pre-pregnancy BMI and gestational weight gain both in clinical categories and across their full ranges were associated with higher risks of childhood overweight/obesity, with the strongest effects in late childhood (Odds Ratios (OR) for overweight/obesity in early-, mid- and late childhood, respectively: 1.66 (95% Confidence Interval (CI): 1.56, 1.78), OR 1.91 (95% CI: 1.85, 1.98), and OR 2.28 (95% CI: 2.08, 2.50) for maternal overweight, OR 2.43 (95% CI: 2.24, 2.64), OR 3.12 (95% CI: 2.98, 3.27), and OR 4.47 (95% CI: 3.99, 5.23) for maternal obesity, and OR 1.39 (95% CI: 1.30, 1.49), OR 1.55 (95% CI: 1.49, 1.60), and 1.72 (95% CI: 1.56, 1.91) for excessive gestational weight gain. The proportions of childhood overweight/obesity prevalence attributable to maternal overweight, maternal obesity and excessive gestational weight gain ranged from 10.2 to 21.6%. Relative to the effect of maternal BMI, excessive gestational weight gain only slightly increased the risk of childhood overweight/obesity within each clinical BMI category (P-values for interactions of maternal BMI with gestational weight gain: p=0.038, p<0.001 and p=0.637, in early-, mid- and late childhood, respectively). Limitations of this study include the self-report of maternal BMI and gestational weight gain for some of the cohorts, and the potential of residual confounding. Also, as this study only included participants from Europe, North-America and Australia, results need to be interpreted with caution with respect to other populations. Conclusions: In this study, higher maternal pre-pregnancy BMI and gestational weight gain were associated with an increased risk of childhood overweight/obesity, with the strongest effects at later ages. The additional effect of gestational weight gain in women who are overweight or obese before pregnancy is small. Given the large population impact, future intervention trials aiming to reduce the prevalence of childhood overweight and obesity should focus on maternal weight status before pregnancy, in addition to weight gain during pregnancy.

Polarization and structure of relativistic parsec-scale AGN jets

Abstract: We consider the polarization properties of optically thin synchrotron radiation emitted by relativistically moving electron-positron jets carrying large-scale helical magnetic fields. In our model, the jet is cylindrical, and the emitting plasma moves parallel to the jet axis with a characteristic Lorentz factor {Lambda}. We draw attention to the strong influence that the bulk relativistic motion of the emitting relativistic particles has on the observed polarization. Our computations predict and explain the following behavior. (1) For jets unresolved in the direction perpendicular to their direction of propagation, the position angle of the electric vector of the linear polarization has a bimodal distribution, being oriented either parallel or perpendicular to the jet. (2) If an ultra-relativistic jet with {Lambda} >> 1 whose axis makes a small angle to the line of sight, {theta} {approx} 1/{Lambda}, experiences a relatively small change in the direction of propagation, velocity or pitch angle of the magnetic fields, the polarization is likely to remain parallel or perpendicular; on the other hand, in some cases, the degree of polarization can exhibit large variations and the polarization position angle can experience abrupt 90{sup o} changes. This change is more likely to occur in jets with flatter spectra. (3)more » In order for the jet polarization to be oriented along the jet axis, the intrinsic toroidal magnetic field (in the frame of the jet) should be of the order of or stronger than the intrinsic poloidal field; in this case, the highly relativistic motion of the jet implies that, in the observer's frame, the jet is strongly dominated by the toroidal magnetic field B{sub {phi}}/B{sub z} {ge} {Lambda}. (4) The emission-weighted average pitch angle of the intrinsic helical field in the jet must not be too small to produce polarization along the jet axis. In force-free jets with a smooth distribution of emissivities, the emission should be generated in a limited range of radii not too close to the jet core. (5) For mildly relativistic jets, when a counter jet can be seen, the polarization of the counter jet is preferentially orthogonal to the axis, unless the jet is strongly dominated by the toroidal magnetic field in its rest frame. (6) For resolved jets, the polarization pattern is not symmetric with respect to jet axis. Under certain conditions, this can be used to deduce the direction of the spin of the central object (black hole or disk), whether it is aligned or anti-aligned with the jet axis. (7) In resolved ''cylindrical shell'' type jets, the central parts of the jet are polarized along the axis, while the outer parts are polarized orthogonal to it, in accordance with observations. We conclude that large-scale magnetic fields can explain the salient polarization properties of parsec-scale AGN jets. Since the typical degrees of polarization are {le} 15%, the emitting parts of the jets must have comparable rest-frame toroidal and poloidal fields. In this case, most relativistic jets are strongly dominated by the toroidal magnetic field component in the observer's frame, B{sub {phi}}/B{sub z} {approx} {Lambda}. We also discuss the possibility that relativistic AGN jets may be electromagnetically (Poynting flux) dominated. In this case, dissipation of the toroidal magnetic field (and not fluid shocks) may be responsible for particle acceleration.« less

Bacteriophage and their lysins for elimination of infectious bacteria

Abstract: When phages were originally identified, the possibility of using them as antibacterial agents against pathogens was immediately recognized and put into practise based on the knowledge available at the time. However, with the advent of antibiotics a decline in the use of phage as therapeutics followed. Phages did, however, become more useful in the study of fundamental aspects of molecular biology and in the diagnostic laboratory for the identification of pathogenic bacteria. More recently, the original application of phage as therapeutics to treat human and animal infections has been rekindled, particularly in an era where antibiotic resistance has become so problematic/commonplace. Phage lysins have also been studied and utilized in their own right as potential therapeutics for the treatment of bacterial infections. Indeed the past decade has seen a considerable amount of research worldwide focused on the engineering of phages as antibacterial agents in a wide range of applications. Furthermore, the US Food and Drug Administration and/or the US Department of Agriculture have recently approved commercial phage preparations to prevent bacterial contamination of livestock, food crops, meat and other foods. Such developments have prompted this review into the status of phage research as it pertains to the control of infectious bacteria.