Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels

The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity filter of the channel is used. The selectivity filter of this channel type contains aspartate (D), glutamate (E), lysine (K), and alanine (A) residues (the DEKA locus). We use Grand Canonical Monte Carlo simulations to compute equilibrium binding selectivity in the selectivity filter and to obtain various terms of the excess chemical potential from a particle insertion procedure based on Widom's method. We show that K$^{+}$ ions in competition with Na$^{+}$ are efficiently excluded from the selectivity filter due to entropic hard sphere exclusion. The dielectric constant of protein has no effect on this selectivity. Ca$^{2+}$ ions, on the other hand, are excluded from the filter due to a free energetic penalty which is enhanced by the low dielectric constant of protein.Comment: 14 pages, 7 figure

Cosmology with intensity mapping techniques using atomic and molecular lines

We present a systematic study of the intensity mapping technique using updated models for the different emission lines from galaxies and identify which ones are more promising for cosmological studies of the post reionization epoch. We consider the emission of ${\rm Ly\alpha}$, ${\rm H\alpha}$, H$\beta$, optical and infrared oxygen lines, nitrogen lines, CII and the CO rotational lines. We then identify that ${\rm Ly\alpha}$, ${\rm H\alpha}$, OII, CII and the lowest rotational CO lines are the best candidates to be used as IM probes. These lines form a complementary set of probes of the galaxies emission spectra. We then use reasonable experimental setups from current, planned or proposed experiments to access the detectability of the power spectrum of each emission line. Intensity mapping of ${\rm Ly\alpha}$ emission from $z=2$ to 3 will be possible in the near future with HETDEX, while far-infrared lines require new dedicated experiments. We also show that the proposed SPHEREx satellite can use OII and ${\rm H\alpha}$ IM to study the large-scale distribution of matter in intermediate redshifts of 1 to 4. We found that submilimeter experiments with bolometers can have similar performances at intermediate redshifts using CII and CO(3-2).Comment: 18 pages, 21 figures, 5 tables, published in MNRAS, typos correcte

Split-sideband spectroscopy in slowly modulated optomechanics

Optomechanical coupling between the motion of a mechanical oscillator and a cavity represents a new arena for experimental investigation of quantum effects on the mesoscopic and macroscopic scale.The motional sidebands of the output of a cavity offer ultra-sensitive probes of the dynamics. We introduce a scheme whereby these sidebands split asymmetrically and show how they may be used as experimental diagnostics and signatures of quantum noise limited dynamics. We show split-sidebands with controllable asymmetry occur by simultaneously modulating the light-mechanical coupling $g$ and $\omega_M$ - slowly and out of-phase. Such modulations are generic but already occur in optically trapped set-ups where the equilibrium point of the oscillator is varied cyclically. We analyse recently observed, but overlooked, experimental split-sideband asymmetries; although not yet in the quantum regime, the data suggests that split sideband structures are easily accessible to future experiments

Nonlinear Interferometry via Fock State Projection

We use a photon-number resolving detector to monitor the photon number distribution of the output of an interferometer, as a function of phase delay. As inputs we use coherent states with mean photon number up to seven. The postselection of a specific Fock (photon-number) state effectively induces high-order optical non-linearities. Following a scheme by Bentley and Boyd [S.J. Bentley and R.W. Boyd, Optics Express 12, 5735 (2004)] we explore this effect to demonstrate interference patterns a factor of five smaller than the Rayleigh limit.Comment: 4 pages, 5 figure

Critical steps to ensure the successful reintroduction of the Eurasian red squirrel

Pasos fundamentales para garantizar la eficacia de la reintroducción de la ardilla roja El objetivo de las estrategias de reintroducción de fauna silvestre es establecer poblaciones viables a largo plazo, fomentar la concienciación con respecto a la conservación y aportar beneficios económicos para las comunidades locales. La ardilla roja (Sciurus vulgaris), que estaba extinta en Portugal desde el s. XVI, fue reintroducida en varios parques urbanos en la década de los años 90, principalmente con fines estéticos y recreativos. Evaluamos la eficacia de esta reintroducción en dos parques urbanos y describimos los pasos fundamentales de la misma. Se evaluaron la utilización del hábitat, la densidad y abundancia de la población y las medidas de gestión adoptadas durante los proyectos de reintroducción. Las reintroducciones fueron relativamente eficaces dado a que las ardillas seguían presentes 20 años después de la liberación. No obstante, las poblaciones en ambos parques están disminuyendo debido a la falta de una gestión activa y a la mala calidad del hábitat. La reintroducción eficaz de la ardilla roja en zonas donde no hay ardillas arborícolas exóticas conlleva tres etapas fundamentales. La etapa previa al proyecto comprende estudios sobre la calidad del hábitat; la proximidad genética entre los donantes y la población silvestre más cercana, y la salud de las poblaciones donantes. En la etapa de liberación, el número de individuos liberados dependerá de la variabilidad de los recursos disponibles; asimismo, se ha observado que la técnica de liberación dura es un método eficaz y viable desde el punto de vista económico. Las actividades posteriores a la liberación deberían analizar la adaptación, mitigar la mortalidad, hacer un seguimiento de la necesidad de aportar alimentación complementaria, prestar apoyo veterinario y fomentar la sensibilización pública y la educación.Wildlife reintroduction strategies aim to establish viable long–term populations, promote conservation awareness and provide economic benefits for local communities. In Portugal, the Eurasian red squirrel (Sciurus vulgaris) became extinct in the 16th century and was reintroduced in urban parks in the 1990s, mainly for aesthetic and leisure purposes. We evaluated the success of this reintroduction in two urban parks and here described the critical steps. We assessed habitat use, population density and abundance, and management steps carried out during reintroduction projects. Reintroductions have been successful to some extent given squirrels are present 20 years after release. However, populations in both parks are declining due to the lack of active management and poor quality habitat. Successful reintroduction of Eurasian red squirrel in areas without competition of alien tree squirrels involves three critical main stages. The pre–project stage includes studies on habitat quality, genetic proximity between donors and closest wild population, and health of donor stocks. In the release stage, the number of individuals released will depend on resource variability, and the hard release technique is an effective and economically viable method. Post–release activities should evaluate adaptation, mitigate mortality, monitor the need for supplementary feeding, provide veterinary support, and promote public awareness and education.Pasos fundamentales para garantizar la eficacia de la reintroducción de la ardilla roja El objetivo de las estrategias de reintroducción de fauna silvestre es establecer poblaciones viables a largo plazo, fomentar la concienciación con respecto a la conservación y aportar beneficios económicos para las comunidades locales. La ardilla roja (Sciurus vulgaris), que estaba extinta en Portugal desde el s. XVI, fue reintroducida en varios parques urbanos en la década de los años 90, principalmente con fines estéticos y recreativos. Evaluamos la eficacia de esta reintroducción en dos parques urbanos y describimos los pasos fundamentales de la misma. Se evaluaron la utilización del hábitat, la densidad y abundancia de la población y las medidas de gestión adoptadas durante los proyectos de reintroducción. Las reintroducciones fueron relativamente eficaces dado a que las ardillas seguían presentes 20 años después de la liberación. No obstante, las poblaciones en ambos parques están disminuyendo debido a la falta de una gestión activa y a la mala calidad del hábitat. La reintroducción eficaz de la ardilla roja en zonas donde no hay ardillas arborícolas exóticas conlleva tres etapas fundamentales. La etapa previa al proyecto comprende estudios sobre la calidad del hábitat; la proximidad genética entre los donantes y la población silvestre más cercana, y la salud de las poblaciones donantes. En la etapa de liberación, el número de individuos liberados dependerá de la variabilidad de los recursos disponibles; asimismo, se ha observado que la técnica de liberación dura es un método eficaz y viable desde el punto de vista económico. Las actividades posteriores a la liberación deberían analizar la adaptación, mitigar la mortalidad, hacer un seguimiento de la necesidad de aportar alimentación complementaria, prestar apoyo veterinario y fomentar la sensibilización pública y la educación

Development of bovine embryos cultured with media containing glucose.

Blastocyst (BL) expansion and blastocoel formation are coupled with increase in the glucose (GLU) metabolism, which is higher in morphologically normal than in degenerate embryos (Rieger et aI., 1992). This study aimed to determine the dose levei and duration of addition of GLU to culture medium that ensures the best results in development of in vitro produced bovine embryos

Stripe-tetragonal phase transition in the 2D Ising model with dipole interactions: Partition-function zeros approach

We have performed multicanonical simulations to study the critical behavior of the two-dimensional Ising model with dipole interactions. This study concerns the thermodynamic phase transitions in the range of the interaction \delta where the phase characterized by striped configurations of width h=1 is observed. Controversial results obtained from local update algorithms have been reported for this region, including the claimed existence of a second-order phase transition line that becomes first order above a tricritical point located somewhere between \delta=0.85 and 1. Our analysis relies on the complex partition function zeros obtained with high statistics from multicanonical simulations. Finite size scaling relations for the leading partition function zeros yield critical exponents \nu that are clearly consistent with a single second-order phase transition line, thus excluding such tricritical point in that region of the phase diagram. This conclusion is further supported by analysis of the specific heat and susceptibility of the orientational order parameter.Comment: to appear in Phys. Rev.

R-matrices of three-state Hamiltonians solvable by Coordinate Bethe Ansatz

We review some of the strategies that can be implemented to infer an $R$-matrix from the knowledge of its Hamiltonian. We apply them to the classification achieved in arXiv:1306.6303, on three state $U(1)$-invariant Hamiltonians solvable by CBA, focusing on models for which the $S$-matrix is not trivial. For the 19-vertex solutions, we recover the $R$-matrices of the well-known Zamolodchikov--Fateev and Izergin--Korepin models. We point out that the generalized Bariev Hamiltonian is related to both main and special branches studied by Martins in arXiv:1303.4010, that we prove to generate the same Hamiltonian. The 19-vertex SpR model still resists to the analysis, although we are able to state some no-go theorems on its $R$-matrix. For 17-vertex Hamiltonians, we produce a new $R$-matrix.Comment: 22 page