Geometric Algebras and Extensors

This is the first paper in a series (of four) designed to show how to use geometric algebras of multivectors and extensors to a novel presentation of some topics of differential geometry which are important for a deeper understanding of geometrical theories of the gravitational field. In this first paper we introduce the key algebraic tools for the development of our program, namely the euclidean geometrical algebra of multivectors Cl(V,G_{E}) and the theory of its deformations leading to metric geometric algebras Cl(V,G) and some special types of extensors. Those tools permit obtaining, the remarkable golden formula relating calculations in Cl(V,G) with easier ones in Cl(V,G_{E}) (e.g., a noticeable relation between the Hodge star operators associated to G and G_{E}). Several useful examples are worked in details fo the purpose of transmitting the "tricks of the trade".Comment: This paper (to appear in Int. J. Geom. Meth. Mod. Phys. 4 (6) 2007) is an improved version of material appearing in math.DG/0501556, math.DG/0501557, math.DG/050155

TYPOLOGY OF THE TRANSFORMATIONS OCCURRED IN THE PERI-URBAN SPACE OF HUERTA DE VALENCIA. EVIDENCE FROM NORTH ARCH OF VALENCIA (SPAIN)

[EN] This paper present the outputs obtained from the measurement and classification of the different types of changes happened in the last 70 years on the Northern area of expansion of the city of Valencia. The city has progressively been covering, with different rhythms and intensities, the space of La Huerta. We can identify between 1944 and 2014 a group of transformations that occur repetitively, building a change pattern identified as common on the city s expansion evolution. The methodology is based on the analysis and measurement of changes occurred on land structure, land use, buildings occupation and on the traditional structure of non-urban roads. The key sources to measure such changes have been the use of the Cadastre of 1929 1944; 1972; and 1989; the orthophoto collections from the Valencian Regional Library and the evolution of SIOSE mapping. The most outstanding results refer to the surprising resilience of some elements from the structure of La Huerta de Valencia and the discovery and identification of the main transformations patterns that could be generalized to the rest of La Huerta de Valencia.Temes Cordovez, RR.; Moya Fuero, A. (2016). TYPOLOGY OF THE TRANSFORMATIONS OCCURRED IN THE PERI-URBAN SPACE OF HUERTA DE VALENCIA. EVIDENCE FROM NORTH ARCH OF VALENCIA (SPAIN). International Journal of Sustainable Development and Planning. 11(6):996-1003. doi:10.2495/SDP-V11-N6-996-1003S996100311

Temporal factorization of a non-stationary electromagnetic cavity field

When an electromagnetic field is confined in a cavity of variable length, real photons may be generated from vacuum fluctuations due to highly nonadiabatic boundary conditions. The corresponding effective Hamiltonian is time-dependent and contains infinite intermode interactions. Considering one of the cavity mirrors fixed and the other describing uniform motion (zero acceleration), we show that it is possible to factorize the entire temporal dependency and write its formal solution, i.e., the Hamiltonian becomes a product of a time-dependent function and a time-independent operator. With this factorization, we prove in detail that the photon production is proportional to the Planck factor involving a velocity-dependent effective temperature. This temperature significantly limits photon generation even for ultra-relativistic motion. The time-dependent unitary transformations we introduce to obtain temporal factorization help establishing connections with the shortcuts to adiabaticity of quantum thermodynamics and with the quantum Arnold transformation.Comment: 10 pages, 4 figures. Accepted in Phys. Rev.

The CoRoT Evolution and Seismic Tools Activity: Goals and Tasks

The forthcoming data expected from space missions such as CoRoT require the capacity of the available tools to provide accurate models whose numerical precision is well above the expected observational errors. In order to secure that these tools meet the specifications, a team has been established to test and, when necessary, to improve the codes available in the community. The CoRoT evolution and seismic tool activity (ESTA) has been set up with this mission. Several groups have been involved. The present paper describes the motivation and the organisation of this activity, providing the context and the basis for the presentation of the results that have been achieved so far. This is not a finished task as future even better data will continue to demand more precise and complete tools for asteroseismology.Comment: 11 pages, 3 figures, accepted for publication in Astrophysics and Space Science, 'CoRoT ESTA' special volum

High-energy scissors mode

All the orbital M1 excitations, at both low and high energies, obtained from a rotationally invariant QRPA, represent the fragmented scissors mode. The high-energy M1 strength is almost purely orbital and resides in the region of the isovector giant quadrupole resonance. In heavy deformed nuclei the high-energy scissors mode is strongly fragmented between 17 and 25 MeV (with uncertainties arising from the poor knowledge of the isovector potential). The coherent scissors motion is hindered by the fragmentation and $B(M1) < 0.25 \; \mu^2_N$ for single transitions in this region. The $(e,e^{\prime})$ cross sections for excitations above 17 MeV are one order of magnitude larger for E2 than for M1 excitations even at backward angles.Comment: 20 pages in RevTEX, 5 figures (uuencoded,put with 'figures') accepted for publication in Phys.Rev.

Transcriptional profiling of zebrafish identifies host factors controlling susceptibility to Shigella flexneri

Shigella flexneri is a human-adapted pathovar of Escherichia coli that can invade the intestinal epithelium, causing inflammation and bacillary dysentery. Although an important human pathogen, the host response to S. flexneri has not been fully described. Zebrafish larvae represent a valuable model to study human infections in vivo. Here we use a Shigella-zebrafish infection model to generate mRNA expression profiles of host response to Shigella infection at the whole animal level. Immune response-related processes dominate the signature of early Shigella infection (6 hours post-infection). Consistent with its clearance from the host, the signature of late Shigella infection (24 hours post-infection) is significantly changed, and only a small set of immune-related genes remain differentially expressed, including acod1 and gpr84. Using mutant lines generated by ENU, CRISPR mutagenesis and F0 Crispants, we show that acod1- and gpr84-deficient larvae are more susceptible to Shigella infection. Together, these results highlight the power of zebrafish to model infection by bacterial pathogens and reveal the mRNA expression of the early (acutely infected) and late (clearing) host response to Shigella infection

Orbital M1 versus E2 strength in deformed nuclei: A new energy weighted sum rule

Within the unified model of Bohr and Mottelson we derive the following linear energy weighted sum rule for low energy orbital 1$^+$ excitations in even-even deformed nuclei S_{\rm LE}^{\rm lew} (M_1^{\rm orb}) \cong (6/5) \epsilon (B(E2; 0^+_1 \rightarrow 2_1^+ K=0)/Z e^2^2) \mu^2_N with B(E2) the E2 strength for the transition from the ground state to the first excited state in the ground state rotational band, $$ the charge r.m.s. radius squared and $\epsilon$ the binding energy per nucleon in the nuclear ground state. It is shown that this energy weighted sum rule is in good agreement with available experimental data. The sum rule is derived using a simple ansatz for the intrinsic ground state wave function that predicts also high energy 1$^+$ strength at 2$\hbar \omega$ carrying 50\% of the total $m_1$ moment of the orbital M1 operator.Comment: REVTEX (3.0), 9 pages, RU924