Dynamical Equations For The Period Vectors In A Periodic System Under Constant External Stress

The purpose of this paper is to derive the dynamical equations for the period vectors of a periodic system under constant external stress. The explicit starting point is Newton’s second law applied to halves of the system. Later statistics over indistinguishable translated states and forces associated with transport of momentum are applied to the resulting dynamical equations. In the final expressions, the period vectors are driven by the imbalance between internal and external stresses. The internal stress is shown to have both full interaction and kinetic-energy terms.

Breast is Best? Reasons Why Mothers Decide to Breastfeed or Bottlefeed their Babies and Factors Influencing the Duration of Breastfeeding.

Breastfeeding is known to confer benefits, both in the short term and long term, to the child and also to the mother. Various health-promotion initiatives have aimed to increase breastfeeding rates and duration in the United Kingdom over the past decade. In order to assist in these endeavours, it is essential to understand the reasons why women decide whether to breastfeed and the factors that influence the duration of breastfeeding. This study reports breastfeeding initiation and duration rates of mothers participating in the Growth, Learning and Development study undertaken by the Child Health & Welfare Recognised Research Group. Although this study cannot provide prevalence data for all mothers in Greater Belfast, it can provide useful information on trends within particular groups of the population. In addition, it examines maternally reported reasons for choosing to breastfeed and for breastfeeding cessation. The likelihood of mothers initiating breastfeeding is influenced by factors such as increased age, higher educational attainment and higher socio-economic grouping. The most common reason cited for breastfeeding is that it is “best for baby”. Returning to work is the most important factor in influencing whether mothers continued to breastfeed. Women report different reasons for cessation depending on the age of their child when they stopped breastfeeding. This information should inform health-promotion initiatives and interventions.