Completing NLO QCD Corrections for Tree Level Non-Leptonic Delta F = 1 Decays Beyond the Standard Model

In various extensions of the Standard Model (SM) tree level non-leptonic decays of hadrons receive contributions from new heavy gauge bosons and scalars. Prominent examples are the right-handed W' bosons in left-right symmetric models and charged Higgs (H^\pm) particles in models with extended scalar sector like two Higgs doublet models and supersymmetric models. Even in the case of decays with four different quark flavours involved, to which penguin operators cannot contribute, twenty linearly independent operators, instead of two in the SM, have to be considered. Anticipating the important role of such decays at the LHCb, KEKB and Super-B in Rome and having in mind future improved lattice computations, we complete the existing NLO QCD formulae for these processes by calculating O(alpha_s) corrections to matching conditions for the Wilson coefficients of all contributing operators in the NDR-\bar{MS} scheme. This allows to reduce certain unphysical scale and renormalization scheme dependences in the existing NLO calculations. Our results can also be applied to models with tree-level heavy neutral gauge boson and scalar exchanges in Delta F = 1 transitions and constitute an important part of NLO analyses of those non-leptonic decays to which also penguin operators contribute.Comment: 24 pages, 6 figure

A hypothesis on improving foreign accents by optimizing variability in vocal learning brain circuits

Rapid vocal motor learning is observed when acquiring a language in early childhood, or learning to speak another language later in life. Accurate pronunciation is one of the hardest things for late learners to master and they are almost always left with a non-native accent. Here I propose a novel hypothesis that this accent could be improved by optimizing variability in vocal learning brain circuits during learning. Much of the neurobiology of human vocal motor learning has been inferred from studies on songbirds. Jarvis (2004) proposed the hypothesis that as in songbirds there are two pathways in humans: one for learning speech (the striatal vocal learning pathway), and one for production of previously learnt speech (the motor pathway). Learning new motor sequences necessary for accurate non-native pronunciation is challenging and I argue that in late learners of a foreign language the vocal learning pathway becomes inactive prematurely. The motor pathway is engaged once again and learners maintain their original native motor patterns for producing speech, resulting in speaking with a foreign accent. Further, I argue that variability in neural activity within vocal motor circuitry generates vocal variability that supports accurate non-native pronunciation. Recent theoretical and experimental work on motor learning suggests that variability in the motor movement is necessary for the development of expertise. I propose that there is little trial-by-trial variability when using the motor pathway. When using the vocal learning pathway variability gradually increases, reflecting an exploratory phase in which learners try out different ways of pronouncing words, before decreasing and stabilizing once the ‘best’ performance has been identified. The hypothesis proposed here could be tested using behavioral interventions that optimize variability and engage the vocal learning pathway for longer, with the prediction that this would allow learners to develop new motor patterns that result in more native-like pronunciation

Implications of coral reef buildup for the controls on atmospheric CO2 since the Last Glacial Maximum

We examine the effect on atmospheric CO2 of the occurrence of increased shallow water carbonate deposition and regrowth of the terrestrial biosphere following the last glacial. We find that contrary to recent speculations that changes in terrestrial carbon storage were primarily responsible for the observed similar to20 ppmv late Holocene CO2 rise, a more likely explanation is coral reef buildup and other forms of shallow water carbonate deposition during this time. The importance of a responsive terrestrial carbon reservoir may instead be as a negative feedback restricting the rate of CO2 rise possible in the early stages of the deglacial transition. This separation in time of the primary impacts of regrowth of the terrestrial biosphere and increased shallow water carbonate deposition explains the occurrence of an early Holocene carbonate preservation event observed in deep-sea sediments. We demonstrate that their combined influence is also consistent with available proxy estimates of deep ocean carbonate ion concentration changes over the last 21 kyr. Accounting for the processes that act on the carbonate chemistry of the ocean as a whole then allows us to place strong constraints on the nature of the remaining processes that must be operating at the deglacial transition. By subtracting the net CO2 effect of coral reef buildup and terrestrial biosphere regrowth from recent high-resolution ice core data, we highlight two periods, from 17.0 to 13.8 kyr and 12.3 to 11.2 kyr BP characterized by sustained rapid rates of CO2 increase (> 12 ppmv kyr(-1)). Because these periods are coincident with Southern Hemisphere "deglaciation,'' we argue that changes in the biogeochemical properties of the Southern Ocean surface are the most likely cause

Dispersion interactions between semiconducting wires

The dispersion energy between extended molecular chains (or equivalently infinite wires) with non-zero band gaps is generally assumed to be expressible as a pair-wise sum of atom-atom terms which decay as $R^{-6}$. Using a model system of two parallel wires with a variable band gap, we show that this is not the case. The dispersion interaction scales as $z^{-5}$ for large interwire separations $z$, as expected for an insulator, but as the band gap decreases the interaction is greatly enhanced; while at shorter (but non-overlapping) separations it approaches a power-law scaling given by $z^{-2}$, \emph{i.e.} the dispersion interaction expected between \emph{metallic} wires. We demonstrate that these effects can be understood from the increasing length scale of the plasmon modes (charge fluctuations), and their increasing contribution to the molecular dipole polarizability and the dispersion interaction, as the band gaps are reduced. This result calls into question methods which invoke locality assumptions in deriving dispersion interactions between extended small-gap systems.Comment: 8 pages, 5 figure

Statutory erosion of secured creditors' rights: some insights from the United Kingdom

As the American Bankruptcy Institute’s Commission to Study the Reform of Chapter 11 considers the state of business bankruptcy in this country, the narrative on chapter 11 is well-established and oft-repeated. According to this narrative, whereas in the past firms filing for chapter 11 came into the bankruptcy process with at least some unencumbered assets, modern firms tend to have capital structures that are entirely consumed by multiple layers of secured debt. Moreover, as secured creditors have come to dominate capital structures, conventional wisdom has it that they have “captured” chapter 11 to the detriment of unsecured creditors. This development has justifiably troubled many scholars on both efficiency and distributional grounds. However, it remains an open question whether the perceived downsides of secured creditor control can be satisfactorily addressed through bankruptcy law reform. In this Article, Professor Walters examines English attempts to use bankruptcy law to adjust the priority and control rights of secured creditors with the aim of improving the welfare of unsecured creditors. The Article starts from the premise that lenders that are powerful enough to bargain for superior control and priority rights inside or outside of bankruptcy will be equally capable of adjusting to legal changes that affect, or are perceived as affecting their interests. Four ways in which lenders will adjust to “adverse” bankruptcy reform are identified: (i) metabargaining; (ii) adjustments to prebankruptcy behavior; (iii) transactional innovation; and (iv) “shape shifting”. In Parts II and III, the Article then illustrates how English lenders have successfully adjusted to statutory erosion of their priority rights through transactional innovation and to statutory attempts to curb their control rights through “shape shifting”. Walters’ conclusion on the efficacy of bankruptcy law reform is cautionary and skeptical. He assesses English attempts to improve the position of unsecured creditors by dampening the rights of secured creditors as a failed conceit

Problem Based Learning and its use on the Automotive Engineering Design Course at Coventry University

The Automotive Engineering Design course at Coventry University has been in operation since October 1989 and has earned a reputation for creating able engineers well prepared for industry. When originally conceived, a problem led approach to learning was adopted across the course. This approach best enables the course objectives to be satisfied. However, there is nothing new about problem-based learning for engineering design educators but for our engineering science colleagues a degree of novelty has been encountered by this approach. But is the success of the course purely down to this teaching and learning approach? This paper will discuss the opportunities, benefits and limitations of the problem-led approach being extended across a whole course. The paper also will address how the use of industrially defined problems in engineering design projects has been critical to the development of the course. The paper will then attempt to identify the key factors that lie behind the success of the Automotive Engineering Design course. Finally, a set of best practice guidelines for engineering design education will be presented based upon my experiences as the Course Tutor and a teacher of engineering design on this course

Propagation mechanisms for the Madden-Julian Oscillation

The Madden-Julian Oscillation (MJO) is examined using 20 years of outgoing longwave radiation and NCEP-NCAR reanalysis data. Two mechanisms for the eastward propagation and regeneration of the convective anomalies are suggested. The first is a local mechanism operating over the warm pool region. At the phase of the MJO with a dipole structure to the convection anomalies, there is enhanced tropical convection over the eastern Indian Ocean and reduced convection over the western Pacific. Over the equatorial western Indian Ocean, the equatorial Rossby wave response to the west of the enhanced convection includes a region of anomalous surface divergence associated with the anomalous surface westerlies and pressure ridge. This tends to suppress ascent in the boundary layer and shuts off the deep convection, eventually leading to a convective anomaly of the opposite sign. Over the Indonesian sector, the equatorial Kelvin wave response to the east of the enhanced convection includes a region of anomalous surface convergence into the anomalous equatorial surface easterlies and pressure trough, which will tend to favour convection in this region. The Indonesian sector is also influenced by an equatorial Rossby wave response (of opposite sign) to the west of the reduced convection over the western Pacific, which also has a region of anomalous surface convergence associated with its anomalous equatorial surface easterlies and pressure trough. Hence, convective anomalies of either sign tend to erode themselves from the west and initiate a convective anomaly of opposite sign via their equatorial Rossby wave response, and expand to the east via their equatorial Kelvin wave response. The second is a global mechanism involving an anomaly completing a circuit of the equator. Enhanced convection over the tropical western Pacific excites a negative sea level pressure (SLP) anomaly which radiates rapidly eastward as a dry equatorial Kelvin wave at approximately 35 m s-1 over the eastern Pacific. It is blocked by the orographic barrier of the Andes and Central America for several days before propagating through the gap at Panama. After rapidly propagating as a dry equatorial Kelvin wave over the Atlantic, the SLP anomaly is delayed further by the East African Highlands before it reaches the Indian Ocean and coincides with the development of enhanced convection at the start of the next MJO cycle