Detection of charge motion in a non-metallic silicon isolated double quantum dot

As semiconductor device dimensions are reduced to the nanometer scale, effects of high defect density surfaces on the transport properties become important to the extent that the metallic character that prevails in large and highly doped structures is lost and the use of quantum dots for charge sensing becomes complex. Here we have investigated the mechanism behind the detection of electron motion inside an electrically isolated double quantum dot that is capacitively coupled to a single electron transistor, both fabricated from highly phosphorous doped silicon wafers. Despite, the absence of a direct charge transfer between the detector and the double dot structure, an efficient detection is obtained. In particular, unusually large Coulomb peak shifts in gate voltage are observed. Results are explained in terms of charge rearrangement and the presence of inelastic cotunneling via states at the periphery of the single electron transistor dot

Recombinant anticoccidial vaccines - a cup half full?

Eimeria species parasites can cause the disease coccidiosis, most notably in chickens. The occurrence of coccidiosis is currently controlled through a combination of good husbandry, chemoprophylaxis and/or live parasite vaccination; however, scalable, cost-effective subunit or recombinant vaccines are required. Many antigens have been proposed for use in novel anticoccidial vaccines, supported by the capacity to reduce disease severity or parasite replication, increase body weight gain in the face of challenge or improve feed conversion under experimental conditions, but none has reached commercial development. Nonetheless, the protection against challenge induced by some antigens has been within the lower range described for the ionophores against susceptible isolates or current live vaccines prior to oocyst recycling. With such levels of efficacy it may be that combinations of anticoccidial antigens already described are sufficient for development as novel multi-valent vaccines, pending identification of optimal delivery systems. Selection of the best antigens to be included in such vaccines can be informed by knowledge defining the natural occurrence of specific antigenic diversity, with relevance to the risk of immediate vaccine breakthrough, and the rate at which parasite genomes can evolve new diversity. For Eimeria, such data are now becoming available for antigens such as apical membrane antigen 1 (AMA1) and immune mapped protein 1 (IMP1) and more are anticipated as high-capacity, high-throughput sequencing technologies become increasingly accessible

Infall and Outflow around the HH 212 protostellar system

HH 212 is a highly collimated jet discovered in H2 powered by a young Class 0 source, IRAS 05413-0104, in the L1630 cloud of Orion. We have mapped around it in 1.33 mm continuum, 12CO ($J=2-1$), 13CO ($J=2-1$), C18O ($J=2-1$), and SO ($J_K = 6_5-5_4$) emission at $\sim$ \arcs{2.5} resolution with the Submillimeter Array. A dust core is seen in the continuum around the source. A flattened envelope is seen in C18O around the source in the equator perpendicular to the jet axis, with its inner part seen in 13CO. The structure and kinematics of the envelope can be roughly reproduced by a simple edge-on disk model with both infall and rotation. In this model, the density of the disk is assumed to have a power-law index of $p=-1.5$ or -2, as found in other low-mass envelopes. The envelope seems dynamically infalling toward the source with slow rotation because the kinematics is found to be roughly consistent with a free fall toward the source plus a rotation of a constant specific angular momentum. A 12CO outflow is seen surrounding the H2 jet, with a narrow waist around the source. Jetlike structures are also seen in 12CO near the source aligned with the H2 jet at high velocities. The morphological relationship between the H2 jet and the 12CO outflow, and the kinematics of the 12CO outflow along the jet axis are both consistent with those seen in a jet-driven bow shock model. SO emission is seen around the source and the H2 knotty shocks in the south, tracing shocked emission around them.Comment: 17 pages, 11 figures, Accepted by the Ap

Resonance contributions to HBT correlation radii

We study the effect of resonance decays on intensity interferometry for heavy ion collisions. Collective expansion of the source leads to a dependence of the two-particle correlation function on the pair momentum K. This opens the possibility to reconstruct the dynamics of the source from the K-dependence of the measured HBT radii. Here we address the question to what extent resonance decays can fake such a flow signal. Within a simple parametrization for the emission function we present a comprehensive analysis of the interplay of flow and resonance decays on the one- and two-particle spectra. We discuss in detail the non-Gaussian features of the correlation function introduced by long-lived resonances and the resulting problems in extracting meaningful HBT radii. We propose to define them in terms of the second order q-moments of the correlator C(q, K). We show that this yields a more reliable characterisation of the correlator in terms of its width and the correlation strength `lambda' than other commonly used fit procedures. The normalized fourth-order q-moments (kurtosis) provide a quantitative measure for the non-Gaussian features of the correlator. At least for the class of models studied here, the kurtosis helps separating effects from expansion flow and resonance decays, and provides the cleanest signal to distinguish between scenarios with and without transverse flow.Comment: 23 pages, twocolumn RevTeX, 12 eps-figures included, minor changes following referee comment

Delivering sustainable, resilient and liveable cities via transformed governance

In the context of steadily declining Natural Capital and universal recognition of the imperative to reverse this trend before we get to the point that nature is not able to restore itself, cities have a crucial role to play. The UK Government commissioned a comprehensive study into the value of biodiversity, and by extension nature, reinforcing “why we should change our ways”—yet what is missing is the “how?”. This paper uniquely describes both the “how?” and a conclusive demonstration of the remarkable benefits of implementing it in a city. Critical to this process, it took a UK Parliamentary Inquiry to reveal that nature has become invisible within the economy, yet the ecological ecosystem services nature provides have enormous benefits to both people and the economy. Therefore integration—or seamless weaving—of urban greenspace and nature into people's lives and the places where they live, work, and spend their leisure time is vital. Moreover, what nature does not provide must be provided by engineered systems, and these have an economic cost; put another way, there are enormous cost savings to be made by taking advantage of what nature provides. In addressing these issues, this paper is the definitive paper from a 20-year portfolio of research on how to bring about transformative change in the complex system-of-systems that make up our cities, providing as it does the crucial in-depth research into the many diverse strands of governance—the last link in a chain of the creation, testing and proof of efficacy of methodologies underpinning a theory and practice of change for infrastructure and cities. The impact of this portfolio of research on Birmingham is two-fold: the Star Framework that placed natural environment considerations at the heart of all decision-making in the city, and the successful bid for the largest of the UK Future Parks Accelerator awards. While both are transformative in their different ways, yet mutually supportive, the latter enabled the design of a suite of system interventions from which the value of Birmingham's greenspaces is estimated to rise from £11.0 billion to £14.4 billion—a remarkable return on investment from the research's conceptualization of Birmingham's urban greenspace as a “business” (with its associated business models). In achieving this, the necessary enablers of thinking and practicing systemically, seamlessly working across disciplinary boundaries, an unusually strong focus on both the aspirations of all stakeholders and the context in question to define “the problem,” and the testing of proposed system intervention(s) both now and in the future have been iteratively combined. However, it is the critical enabling steps of identifying the complete range of value-generating opportunities that the interventions offer, formulating them into alternative business models to underpin the case for change and ensuring that they are synergistic with all the dimensions of governance that yielded the profound outcomes sought

Microguards and micromessengers of the genome

The regulation of gene expression is of fundamental importance to maintain organismal function and integrity and requires a multifaceted and highly ordered sequence of events. The cyclic nature of gene expression is known as ‘transcription dynamics’. Disruption or perturbation of these dynamics can result in significant fitness costs arising from genome instability, accelerated ageing and disease. We review recent research that supports the idea that an important new role for small RNAs, particularly microRNAs (miRNAs), is in protecting the genome against short-term transcriptional fluctuations, in a process we term ‘microguarding’. An additional emerging role for miRNAs is as ‘micromessengers’—through alteration of gene expression in target cells to which they are trafficked within microvesicles. We describe the scant but emerging evidence that miRNAs can be moved between different cells, individuals and even species, to exert biologically significant responses. With these two new roles, miRNAs have the potential to protect against deleterious gene expression variation from perturbation and to themselves perturb the expression of genes in target cells. These interactions between cells will frequently be subject to conflicts of interest when they occur between unrelated cells that lack a coincidence of fitness interests. Hence, there is the potential for miRNAs to represent both a means to resolve conflicts of interest, as well as instigate them. We conclude by exploring this conflict hypothesis, by describing some of the initial evidence consistent with it and proposing new ideas for future research into this exciting topic

Static and Dynamic Properties of Dissipative Particle Dynamics

The algorithm for the DPD fluid, the dynamics of which is conceptually a combination of molecular dynamics, Brownian dynamics and lattice gas automata, is designed for simulating rheological properties of complex fluids on hydrodynamic time scales. This paper calculates the equilibrium and transport properties (viscosity, self-diffusion) of the thermostated DPD fluid explicitly in terms of the system parameters. It is demonstrated that temperature gradients cannot exist, and that there is therefore no heat conductivity. Starting from the N-particle Fokker-Planck, or Kramers' equation, we prove an H-theorem for the free energy, obtain hydrodynamic equations, and derive a non-linear kinetic equation (the Fokker-Planck-Boltzmann equation) for the single particle distribution function. This kinetic equation is solved by the Chapman-Enskog method. The analytic results are compared with numerical simulations.Comment: 22 pages, LaTeX, 3 Postscript figure

Spin, charge and orbital ordering in ferrimagnetic insulator YBaMn2_2O5_5

The oxygen-deficient (double) perovskite YBaMn$_2$O$_5$, containing corner-linked MnO$_5$ square pyramids, is found to exhibit ferrimagnetic ordering in its ground state. In the present work we report generalized-gradient-corrected, relativistic first-principles full-potential density-functional calculations performed on YBaMn$_2$O$_5$ in the nonmagnetic, ferromagnetic and ferrimagnetic states. The charge, orbital and spin orderings are explained with site-, angular momentum- and orbital-projected density of states, charge-density plots, electronic structure and total energy studies. YBaMn$_2$O$_5$ is found to stabilize in a G-type ferrimagnetic state in accordance with experimental results. The experimentally observed insulating behavior appears only when we include ferrimagnetic ordering in our calculation. We observed significant optical anisotropy in this material originating from the combined effect of ferrimagnetic ordering and crystal field splitting. In order to gain knowledge about the presence of different valence states for Mn in YBaMn$_2$O$_5$ we have calculated $K$-edge x-ray absorption near-edge spectra for the Mn and O atoms. The presence of the different valence states for Mn is clearly established from the x-ray absorption near-edge spectra, hyperfine field parameters and the magnetic properties study. Among the experimentally proposed structures, the recently reported description based on $P$4/$nmm$ is found to represent the stable structure