A Study into the Participation and Engagement of Young People with Physics in Post-Compulsary Education

This report, submitted in conjunction with the portfolio, presents an investigation into the participation and engagement of young people with physics in post-compulsory education. This study explores the reasons why we must encourage more young people to study physics, as it is a challenging yet rewarding discipline that can lead to a wide variety of employment opportunities. The study also considers how we can encourage more young people to study physics, including factors inside and outside of the classroom. The portfolio consists of ten separate reports, each addressing a different aspect of the study. The study is of a mixed methods design, employing a range of qualitative and quantitative data, as well as two action research projects. As a professional doctorate study, it is based largely upon my professional practice as a teacher and manager at a large college of further education. Whilst the college is based in the north east of England, my findings are not confined to this geographical region, but extend across the UK. The study shows that after considerable interventions and initiatives, the number of GCSE candidates in physics has increased over the past ten years, with the gender balance being almost equal. Within post-compulsory education, the situation is very different, as the number of young people who study physics at A level and university is far less than we need to fill the ‘skills gap’ in the UK. The gender issue becomes far more prominent at each stage of the educational ladder. It was found that whilst the teacher can have a profound influence upon students’ enjoyment of a subject, external factors such as parents, educational establishment, role models and the media can all influence the decisions made by young people in post-compulsory education. These factors are investigated within this study. One of the main findings was that physics, as an academic subject, is thriving in the independent sector and prestigious universities, and is arguably becoming an ‘elite’ subject. The report concludes with a series of recommendations for teachers, educational establishments and external organisations, which are aimed at increasing the numbers of young people who progress to study physics in post-compulsory education. Some of the suggestions include increasing the number of specialist physics teachers (particularly female physics teachers) and improving the inter-personal skills of physics teachers. The report also suggests that due to the current status of teachers in further education, it is difficult to attract and retain good physics teachers when there are many other financially rewarding careers available for physics graduates

Radiative corrections to hard spectator scattering in B→ππB\to \pi\pi decays

We present the calculation of the next-to-leading corrections to the tree amplitudes which appear in the description of non-leptonic B-decays in the factorization approach. These corrections, together with radiative corrections to the jet functions, represent the full next-to-leading contributions to the dominant hard spectator scattering term generated by operators $O_{1,2}$ in the decay amplitudes. Using obtained analytical results we estimate $B\to\pi\pi$ branchings fractions in the physical (or BBNS) factorization scheme. We have also found that the imaginary part generated in the hard spectator scattering term is rather large compared to the imaginary part of the vertex contribution.Comment: text is improved and typos are corrected, accepted for publication in JHE

Whole egg consumption and cortical bone in healthy children

Eggs contain bioactive compounds thought to benefit pediatric bone. This cross-sectional study shows a positive link between childhood egg intake and radius cortical bone. If randomized trials confirm our findings, incorporating eggs into children's diets could have a significant impact in preventing childhood fractures and reducing the risk of osteoporosis. INTRODUCTION: This study examined the relationships between egg consumption and cortical bone in children. METHODS: The cross-sectional study design included 294 9-13-year-old black and white males and females. Three-day diet records determined daily egg consumption. Peripheral quantitative computed tomography measured radius and tibia cortical bone. Body composition and biomarkers of bone turnover were assessed using dual-energy X-ray absorptiometry and ELISA, respectively. RESULTS: Egg intake was positively correlated with radius and tibia cortical bone mineral content (Ct.BMC), total bone area, cortical area, cortical thickness, periosteal circumference, and polar strength strain index in unadjusted models (r = 0.144-0.224, all P < 0.050). After adjusting for differences in race, sex, maturation, fat-free soft tissue mass (FFST), and protein intakes, tibia relationships were nullified; however, egg intake remained positively correlated with radius Ct.BMC (r = 0.138, P = 0.031). Egg intake positively correlated with total body bone mineral density, BMC, and bone area in the unadjusted models only (r = 0.119-0.224; all P < 0.050). After adjusting for covariates, egg intake was a positive predictor of radius FFST (β = 0.113, P < 0.050) and FFST was a positive predictor of Ct.BMC (β = 0.556, P < 0.050) in path analyses. There was a direct influence of egg on radius Ct.BMC (β = 0.099, P = 0.035), even after adjusting for the mediator, FFST (β = 0.137, P = 0.020). Egg intake was positively correlated with osteocalcin in both the unadjusted (P = 0.005) and adjusted (P = 0.049) models. CONCLUSION: If the positive influence of eggs on Ct.BMC observed in this study is confirmed through future randomized controlled trials, whole eggs may represent a viable strategy to promote pediatric bone development and prevent fractures

Effects of a seaweed extract on weanling pig growth performance and immune function during an acute enteric disease challenge

A total of 95 pigs (initially 15 lb and 17 d of age) was used in a 28 d growth trial to determine the effects of Ascophyllum nodosum seaweed extract (ANOD) on weanling pig growth performance and immune function in response to enteric disease challenge with Salmonella typhimurium (ST). Experimental treatments were arranged in a 2 x 4 factorial with main effects of disease challenge (control vs. ST challenge) and dietary addition of ANOD (0, 0.5, 1.0, and 2.0% of diet). Results suggest little beneficial effect of dietary ANOD on growth performance or immune response in the presence or absence of ST challenge

Effects of a quillaja saponaria extract on weanling pig growth performance and immune function during an acute enteric disease challenge

A total of 96 pigs (initially 19 lb and 17 d of age) was used in a 28 d growth trial to determine the effects of Quillaja saponaria (QS) extract on weanling pig growth performance and immune function in response to enteric disease challenge with Salmonella typhimurium (ST). Experimental treatments were arranged in a 2 × 4 factorial with main effects of disease challenge (control vs. ST challenge) and dietary addition of QS (0, 4, 8, or 16 oz/ton). The results suggest little beneficial effect of QS on growth performance or immune response in the presence or absence of ST challenge

Subthreshold dynamics of the neural membrane potential driven by stochastic synaptic input

In the cerebral cortex, neurons are subject to a continuous bombardment of synaptic inputs originating from the network's background activity. This leads to ongoing, mostly subthreshold membrane dynamics that depends on the statistics of the background activity and of the synapses made on a neuron. Subthreshold membrane polarization is, in turn, a potent modulator of neural responses. The present paper analyzes the subthreshold dynamics of the neural membrane potential driven by synaptic inputs of stationary statistics. Synaptic inputs are considered in linear interaction. The analysis identifies regimes of input statistics which give rise to stationary, fluctuating, oscillatory, and unstable dynamics. In particular, I show that (i) mere noise inputs can drive the membrane potential into sustained, quasiperiodic oscillations (noise-driven oscillations), in the absence of a stimulus-derived, intraneural, or network pacemaker; (ii) adding hyperpolarizing to depolarizing synaptic input can increase neural activity (hyperpolarization-induced activity), in the absence of hyperpolarization-activated currents

The polarisation of the cone(IRN) Nebula in NGC 2264

The first part of this thesis presents a general review of interstellar gas and dust, and how the study of nebulae has developed. The property of the linear polarisation of light from astronomical objects is a mechanism which has enabled astronomers to extend their knowledge and understanding considerably. Polarisation studies of nebulae have given information on nebular structures, grain size and composition, and the geometrical structures involved. The methods of producing polarisation are discussed, and various models proposed which explain the various observed features. The second part of the thesis deals specifically with the Cone (IRN), which is a small "fan" shaped nebula, found within NGC 2264, very near to Allen’s Infrared object (GL989). Chapter four presents a review of the current knowledge of NGC 2264, and research conducted by other astronomers on the cone (IRN). It explains why it is of particular interest and relevant to this thesis, and also includes some interpretations as to the mechanisms contributing to the observed polarisation. This then leads into the polarisation data, including a brief outline of the construction of the polarimeter. The polarisation maps are presented in the V,R,I filters, and the wavelength dependence of the polarisation is calculated. Chapter six discusses the data, and the possible mechanisms involved. From the results, it is clear that the Cone (IRN) is not a simple reflection nebula. The wavelength dependence of polarisation is mathematically treated and compared to known values, following Serkowski's empirical relationship. Possible configurations of the nebulosity are discussed and interpretations suggested

The long-time dynamics of two hydrodynamically-coupled swimming cells

Swimming micro-organisms such as bacteria or spermatozoa are typically found in dense suspensions, and exhibit collective modes of locomotion qualitatively different from that displayed by isolated cells. In the dilute limit where fluid-mediated interactions can be treated rigorously, the long-time hydrodynamics of a collection of cells result from interactions with many other cells, and as such typically eludes an analytical approach. Here we consider the only case where such problem can be treated rigorously analytically, namely when the cells have spatially confined trajectories, such as the spermatozoa of some marine invertebrates. We consider two spherical cells swimming, when isolated, with arbitrary circular trajectories, and derive the long-time kinematics of their relative locomotion. We show that in the dilute limit where the cells are much further away than their size, and the size of their circular motion, a separation of time scale occurs between a fast (intrinsic) swimming time, and a slow time where hydrodynamic interactions lead to change in the relative position and orientation of the swimmers. We perform a multiple-scale analysis and derive the effective dynamical system - of dimension two - describing the long-time behavior of the pair of cells. We show that the system displays one type of equilibrium, and two types of rotational equilibrium, all of which are found to be unstable. A detailed mathematical analysis of the dynamical systems further allows us to show that only two cell-cell behaviors are possible in the limit of $t\to\infty$, either the cells are attracted to each other (possibly monotonically), or they are repelled (possibly monotonically as well), which we confirm with numerical computations

Cosmological Effects of Radion Oscillations

We show that the redshift of pressureless matter density due to the expansion of the universe generically induces small oscillations in the stabilized radius of extra dimensions (the radion field). The frequency of these oscillations is proportional to the mass of the radion and can have interesting cosmological consequences. For very low radion masses $m_b$ ($m_b\sim10-100 H_0\simeq10^{-32} eV$) these low frequency oscillations lead to oscillations in the expansion rate of the universe. The occurrence of acceleration periods could naturally lead to a resolution of the coincidence problem, without need of dark energy. Even though this scenario for low radion mass is consistent with several observational tests it has difficulty to meet fifth force constraints. If viewed as an effective Brans-Dicke theory it predicts $\omega=-1+\frac{1}{D}$ ($D$ is the number of extra dimensions), while experiments on scales larger than $1mm$ imply $\omega>2500$. By deriving the generalized Newtonian potential corresponding to a massive toroidally compact radion we demonstrate that Newtonian gravity is modified only on scales smaller than $m_b^{-1}$. Thus, these constraints do not apply for $m_b>10^{-3} eV$ (high frequency oscillations) corresponding to scales less than the current experiments ($0.3mm$). Even though these high frequency oscillations can not resolve the coincidence problem they provide a natural mechanism for dark matter generation. This type of dark matter has many similarities with the axion.Comment: Accepted in Phys. Rev. D. Clarifying comments added in the text and some additional references include

Quintessence from Shape Moduli

We show that shape moduli in sub-millimeter extra dimensional scenarios, addressing the gauge hierarchy problem, can dominate the energy density of the universe today. In our scenario, the volume of the extra dimensions is stabilized at a sufficiently high scale to avoid conflicts with nucleosynthesis and solar-system precision gravity experiments, while the shape moduli remain light but couple extremely weakly to brane-localized matter and easily avoid these bounds. Nonlocal effects in the bulk of the extra dimension generate a potential for the shape moduli. The potential has the right form and order of magnitude to account for the present day cosmic acceleration, in a way analogous to models of quintessence as a pseudo Nambu-Goldstone boson.Comment: 8 pages, 1 figur