Probing the nature of Dark Matter with the SKA

Dark Matter (DM) is a fundamental ingredient of our Universe and of structure formation, and yet its nature is elusive to astrophysical probes. Information on the nature and physical properties of the WIMP (neutralino) DM (the leading candidate for a cosmologically relevant DM) can be obtained by studying the astrophysical signals of their annihilation/decay. Among the various e.m. signals, secondary electrons produced by neutralino annihilation generate synchrotron emission in the magnetized atmosphere of galaxy clusters and galaxies which could be observed as a diffuse radio emission (halo or haze) centered on the DM halo. A deep search for DM radio emission with SKA in local dwarf galaxies, galaxy regions with low star formation and galaxy clusters (with offset DM-baryonic distribution, like e.g. the Bullet cluster) can be very effective in constraining the neutralino mass, composition and annihilation cross-section. For the case of a dwarf galaxy, like e.g. Draco, the constraints on the DM annihilation cross-section obtainable with SKA1-MID will be at least a factor $\sim 10^3$ more stringent than the limits obtained by Fermi-LAT in the $\gamma$-rays. These limits scale with the value of the B field, and the SKA will have the capability to determine simultaneously both the magnetic field in the DM-dominated structures and the DM particle properties. The optimal frequency band for detecting the DM-induced radio emission is around $\sim 1$ GHz, with the SKA1-MID Band 1 and 4 important to probe the synchrotron spectral curvature at low-$\nu$ (sensitive to DM composition) and at high-$\nu$ (sensitive to DM mass).Comment: 10 pages, 5 figures, to appear as part of 'Cosmic Magnetism' in proceedings of 'Advancing Astrophysics with the Square Kilometre Array' PoS(AASKA14)10

Plant sulfate transporters in the low phytic acid network : some educated guesses

A few new papers report that mutations in some genes belonging to the group 3 of plant sulfate transporter family result in low phytic acid phenotypes, drawing novel strategies and approaches for engineering the low-phytate trait in cereal grains. Here, we shortly review the current knowledge on phosphorus/sulfur interplay and sulfate transport regulation in plants, to critically discuss some hypotheses that could help in unveiling the physiological links between sulfate transport and phosphorus accumulation in seeds

Identification of magnetosonic modes in Galactic turbulence with synchrotron polarization

The equipartition of magnetic and thermal energy in the interstellar medium (ISM) indicates the magneto-hydrodynamic nature of the interstellar turbulence, which can be decomposed into three wave modes: Alfv\'en, fast and slow magnetosonic modes\cite{Herlofson50,LG01,CL03}. Even for studies performed in the case of subsonic turbulence, the magnetosonic modes have been revealed to be more effective than the Alfv\'enic modes for processes such as cosmic ray (CR) transport and acceleration \cite{YL04,Lynn14}. The multiphase nature of ISM and diversity of driving mechanisms give rise to spatial variation of turbulence properties. Nevertheless, the employed model of magneto-hydrodynamic turbulence is often oversimplified being assumed to be only Alfv\'enic or even hydrodynamic due to a lack of observational evidence. Here we report the employment of our novel method, the signature from polarization analysis (SPA), on unveiling the plasma modes in interstellar turbulence. Its application leads to the first discovery of magnetosonic modes in the Cygnus X region. It is found that the magnetosonic modes overlap to a high degree with Fermi cocoon, consistent with theoretical expectations. Moreover, through comparison with the spectrum at other wavelengths, the plasma modes of turbulence are unveiled in active star formation zones. The SPA casts light on the plasma modes composition of the Galactic turbulence, and marks the onset of a new era in the study of interstellar turbulence and accordingly our understandings of relevant processes including cosmic ray transport and star formation

Different coloured tears: Dual cultural identity and Tangihanga

Although whānau/family that are configured by both Pākehā and Māori identities number significantly within New Zealand, there has been little or no attention paid to the ways in which these identities influence the bereavement processes that will inevitably impact upon the lives of these whānau/family. The present study explored the experiences of an individual, whose whānau/family included two life ways: Māori and Pākehā. Of specific focus was the ways in which these identities influenced his bereavement subsequent to the death of his beloved wife, who was of Māori descent. One elderly male Pākehā participant was interviewed, using an open ended narrative approach. The interview was semi-structured around five broad themes, but the focus was upon the participant’s experiences and his preference in expressing these. The data analysis utilised a thematic process which allowed the participant’s experiences to determine the emergent themes. The results depicted the diversity of issues that may be raised for dual cultural whānau/family within bereavement processes. Two central themes are discussed in relation to intercultural conflict and the eventual resolution that was created. Decision-making processes, cultural and language differences played significant roles within the conflict and exclusion experienced by the participant. Communication and compromise provided resolution to the prior conflicts experienced. This created positive and unexpected outcomes which resulted in increased understandings and the strengthening of links between the participant, his whānau/family and his wife’s marae

Unveiling vertical state downscaling: identity and/or the economy?

State rescaling may take a variety of shapes although scant research has been carried out into the mechanisms and economic incentives that underpin rescaling processes. Recent literature in economics, economic sociology and political economy has identified at least two broad rescaling mechanisms, namely the development of regional identity - operating at the cultural level and proxing preference heterogeneity-, and the heterogeneity in levels of economic development, which influence the extent of regional redistribution. This paper empirically examines the mechanisms of vertical state rescaling by drawing upon empirical evidence from Catalonia and the Basque Country, to explore the evolution of sub-state identity and the rise of inter-territorial fiscal grievances - weakening intraregional economic solidarity. Findings corroborate the idea that the combination of widening sub-national identity raises the costs of managing heterogeneous spatial identities and strengthens support for vertical state downscaling. Similarly, ending regional fiscal solidarity it is found to increase the average income of Catalonia by 37% and even 17% in the Basque Country. However, the effect of regional identity exceeds that of regional redistribution in explaining state rescaling support in the magnitude of one to seven. These findings speak to the debate on the formation of Europe, in that they reveal limits to regional redistribution and highlight the importance of a common spatial identity

Different coloured tears: Dual cultural identity and Tangihanga – A directed study

Although whānau/family that are configured by both Pākehā and Māori identities number significantly within New Zealand, there has been little or no attention paid to the ways in which these identities influence the bereavement processes that will inevitably impact upon the lives of these whānau/family. The present study explored the experiences of an individual, whose whānau/family included two life ways; Māori and Pākehā. Of specific focus was the ways in which these identities influenced his bereavement subsequent to the death of his beloved wife, who was of Māori descent. One elderly male Pākehā participant was interviewed, using an open-ended narrative approach. The interview was semi structured around five broad themes, but the focus was upon the participant’s experiences and his preference in expressing these. The data analysis utilised a thematic process, which allowed the participant’s experiences to determine the emergent themes. The results depicted the diversity of issues that may be raised for dual cultural whānau/family within bereavement processes. Two central themes are discussed in relation to intercultural conflict and the eventual resolution that was created. Decision making processes, cultural and language differences played significant roles within the conflict and exclusion experienced by the participant. Communication and compromise provided resolution to the prior conflicts experienced. This created positive and unexpected outcomes which resulted in increased understandings and the strengthening of links between the participant, his whānau/family and his wife’s marae

Particle-Hole Asymmetry and Brightening of Solitons in A Strongly Repulsive BEC

We study solitary wave propagation in the condensate of a system of hard-core bosons with nearest-neighbor interactions. For this strongly repulsive system, the evolution equation for the condensate order parameter of the system, obtained using spin coherent state averages is different from the usual Gross-Pitaevskii equation (GPE). The system is found to support two kinds of solitons when there is a particle-hole imbalance: a dark soliton that dies out as the velocity approaches the sound velocity, and a new type of soliton which brightens and persists all the way up to the sound velocity, transforming into a periodic wave train at supersonic speed. Analogous to the GPE soliton, the energy-momentum dispersion for both solitons is characterized by Lieb II modes.Comment: Accepted for publication in PRL, Nov 12, 200

Comparison between Eulerian diagnostics and finite-size Lyapunov exponents computed from altimetry in the Algerian basin

Transport and mixing properties of surface currents can be detected from altimetric data by both Eulerian and Lagrangian diagnostics. In contrast with Eulerian diagnostics, Lagrangian tools like the local Lyapunov exponents have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil subgrid filaments generated by chaotic stirring. However, one may wonder whether this theoretical advantage is of practical interest in real-data, mesoscale and submesoscale analysis, because of the uncertainties and resolution of altimetric products, and the non-passive nature of biogeochemical tracers. Here we compare the ability of standard Eulerian diagnostics and the finite-size Lyapunov exponent in detecting instantaneaous and climatological transport and mixing properties. By comparing with sea-surface temperature patterns, we find that the two diagnostics provide similar results for slowly evolving eddies like the first Alboran gyre. However, the Lyapunov exponent is also able to predict the (sub-)mesoscale filamentary process occuring along the Algerian current and above the Balearic Abyssal Plain. Such filaments are also observed, with some mismatch, in sea-surface temperature patterns. Climatologies of Lyapunov exponents do not show any compact relation with other Eulerian diagnostics, unveiling a different structure even at the basin scale. We conclude that filamentation dynamics can be detected by reprocessing available altimetric data with Lagrangian tools, giving insight into (sub-)mesoscale stirring processes relevant to tracer observations and complementing traditional Eulerian diagnostics

Anharmonic effects in ZnO optical phonons probed by Raman spectroscopy

We report Raman spectroscopy measurements on ZnO crystals grown by the vapor transport method and annealed. Vacuum annealing is found to yield single crystals with ultra low density of defects. We focus on the optical E2 phonon linewidth temperature dependence in the 10?500 K range. The linewidth decrease at low temperature is analyzed and discussed in the light of anharmonic up- and down-conversion processes, unveiling strongly different behaviors for the two E2 phonons