Calibration of the TWIST high-precision drift chambers

A method for the precise measurement of drift times for the high-precision drift chambers used in the TWIST detector is described. It is based on the iterative correction of the space-time relationships by the time residuals of the track fit, resulting in a measurement of the effective drift times. The corrected drift time maps are parametrised individually for each chamber using spline functions. Biases introduced by the reconstruction itself are taken into account as well, making it necessary to apply the procedure to both data and simulation. The described calibration is shown to improve the reconstruction performance and to extend significantly the physics reach of the experiment.Comment: 8 pages, 5 figure

A large-scale analysis of mRNA polyadenylation of human and mouse genes

mRNA polyadenylation is a critical cellular process in eukaryotes. It involves 3′ end cleavage of nascent mRNAs and addition of the poly(A) tail, which plays important roles in many aspects of the cellular metabolism of mRNA. The process is controlled by various cis-acting elements surrounding the cleavage site, and their binding factors. In this study, we surveyed genome regions containing cleavage sites [herein called poly(A) sites], for 13 942 human and 11 155 mouse genes. We found that a great proportion of human and mouse genes have alternative polyadenylation (∼54 and 32%, respectively). The conservation of alternative polyadenylation type or polyadenylation configuration between human and mouse orthologs is statistically significant, indicating that alternative polyadenylation is widely employed by these two species to produce alternative gene transcripts. Genes belonging to several functional groups, indicated by their Gene Ontology annotations, are biased with respect to polyadenylation configuration. Many poly(A) sites harbor multiple cleavage sites (51.25% human and 46.97% mouse sites), leading to heterogeneous 3′ end formation for transcripts. This implies that the cleavage process of polyadenylation is largely imprecise. Different types of poly(A) sites, with regard to their relative locations in a gene, are found to have distinct nucleotide composition in surrounding genomic regions. This large-scale study provides important insights into the mechanism of polyadenylation in mammalian species and represents a genomic view of the regulation of gene expression by alternative polyadenylation

Shell and pallet morphology in early developmental stages of Teredo navalis Linne (Bivalvia : Teredinidae)

Dimensions of the shell and provinculum distinguish Teredo novalis larvae from the larvae o[ other bivalve mollusks. In the present scanning electron microscopic stud) of shell and pallet morphology during early ontogenetic stages of this species, the characteristic teredinid provinculum, with two interlocking pairs of small teeth and a wide central loath and socket was well-developed in shells 90 μm long. Provinculurn length ranged from 44 to 51 μm during the larval period. Average lengths of provincular teeth of the left valve were 9.6 μm for the anterior tooth and 8.2 μm for the posterior tooth; in the right valve, lengths were 7.2 μm for the anterior tooth, 16.4 μm for the central tooth, and 6.6 μm for the posterior tooth. Larval shell height prior to metamorphosis was just under 230 μm. Formation of a ligament pit preceded secretion of the dissoconch and development of the apophyses, condyles, and exterior denticulated ridges. Shell loss along the posterior margin of the right valve accompanied a shift in the axis of articulation from the dorsal to the posterior plane; subsequent secretion of the dissoconch restored bilaleral symrnetry. The initial triangular shape of the pallet blade became increasingly rectangular and finally elongate with growth along the distal margin

Removing Barriers, Integrating Research, Spreading Excellence: The European Satellite Communications Network of Excellence "SatNEx"

Within the recently launched 6th Research Framework Programme of the European Commission, 21 major players in satellite communications research have joined forces to implement the European Satellite Communications Network of Excellence (SatNEx). The primary goal of SatNEx is to achieve long-lasting integration of the European research in satellite communication and to develop a common base of knowledge, thus contributing to the realization of the European Research Area. This paper discusses the background and motivation for implementation of the network and highlights the SatNEx mission and key objectives. A top-level overview is then provided including a description of the consortium, the Joint Programme of Activities (JPA) and the time schedule with deliverables and milestones. Finally, an update of ongoing work is presented

Phosphorus transformations in plant-based and bio-waste materials induced by pyrolysis

Strategies are needed to increase the sustainability of phosphorus (P) fertiliser management in agriculture. This paper reports on the potential of pyrolysis treatment to recycle P from renewable materials previously regarded as wastes. The study used K-edge X-ray absorption near-edge structure (XANES) spectroscopy to examine chemical forms of P in the waste feedstock materials and corresponding biochars (pyrolysis at 480–500oC) of four ligno-cellulosic, plant-based residues and five relatively P-rich livestock and water-treatment byproducts, to acquire information on changes in potential P fertiliser value. Pyrolysis enriched P in the biochars by factors of 1.3–4.3, thus offering wide-ranging P fertiliser potential. XANES spectroscopy revealed hydroxyapatite (HAP) as one of the dominant chemical P compounds in the feedstocks, ranging from 14% (rice husks) to 98% (animal bone) of total P. For most materials, pyrolysis increased the proportion of HAP, and pyrophosphates were generated in several cases. These alterations possibly lead to diversity in the P solubility characteristics of the biochars if used as soil amendments; this is an important property of environmentally sound P fertiliser

Comparison of immature and mature bone marrow-derived dendritic cells by atomic force microscopy

A comparative study of immature and mature bone marrow-derived dendritic cells (BMDCs) was first performed through an atomic force microscope (AFM) to clarify differences of their nanostructure and adhesion force. AFM images revealed that the immature BMDCs treated by granulocyte macrophage-colony stimulating factor plus IL-4 mainly appeared round with smooth surface, whereas the mature BMDCs induced by lipopolysaccharide displayed an irregular shape with numerous pseudopodia or lamellapodia and ruffles on the cell membrane besides becoming larger, flatter, and longer. AFM quantitative analysis further showed that the surface roughness of the mature BMDCs greatly increased and that the adhesion force of them was fourfold more than that of the immature BMDCs. The nano-features of the mature BMDCs were supported by a high level of IL-12 produced from the mature BMDCs and high expression of MHC-II on the surface of them. These findings provide a new insight into the nanostructure of the immature and mature BMDCs

Quark and Nucleon Self-Energy in Dense Matter

In a recent work we introduced a nonlocal version of the Nambu--Jona-Lasinio(NJL) model that was designed to generate a quark self-energy in Euclidean space that was similar to that obtained in lattice simulations of QCD. In the present work we carry out related calculations in Minkowski space, so that we can study the effects of the significant vector and axial-vector interactions that appear in extended NJL models and which play an important role in the study of the $\rho$, $\omega$ and $a_1$ mesons. We study the modification of the quark self-energy in the presence of matter and find that our model reproduces the behavior of the quark condensate predicted by the model-independent relation $_{\rho} = <\bar qq>_0(1-\sigma_N\rho_N/f_{\pi}^2m_{\pi}^2 +...)$, where $\sigma_N$ is the pion-nucleon sigma term and $\rho_N$ is the density of nuclear matter. (Since we do not include a model of confinement, our study is restricted to the analysis of quark matter. We provide some discussion of the modification of the above formula for quark matter.) The inclusion of a quark current mass leads to a second-order phase transition for the restoration of chiral symmetry. That restoration is about 80% at twice nuclear matter density for the model considered in this work. We also find that the part of the quark self-energy that is explicitly dependent upon density has a strong negative Lorentz-scalar term and a strong positive Lorentz-vector term, which is analogous to the self-energy found for the nucleon in nuclear matter when one makes use of the Dirac equation for the nucleon. In this work we calculate the nucleon self -energy in nuclear matter using our model of the quark self-energy and obtain satisfactory results.Comment: 19 pages, 8 figures, 2 tables, revte

Resistivity saturation revisited: results from a dynamical mean field theory

We use the dynamical mean field method to study the high-temperature resistivity of electrons strongly coupled to phonons. The results reproduce the qualtiative behavior of the temperature and disorder dependence of the resistivity of the 'A-15' materials, which is commonly described in terms of saturation, but imply that the resistivity does not saturate. Rather, a change in temperature dependence occurs when the scattering becomes strong enough to cause a breakdown of the Migdal approximation.Comment: Minor revisions in response to referee report; latex error corrected so paper prints properl