Topological coupling of dislocations and magnetization vorticity in Spin Density Waves

The rich order parameter of Spin Density Waves allows for an unusual object of a complex topological nature: a half-integer dislocation combined with a semi-vortex of the staggered magnetization. It becomes energetically preferable to ordinary dislocation due to enhanced Coulomb interactions in the semiconducting regime. Generation of these objects changes the narrow band noise frequency.Comment: To be published in Proceedings of ECRYS-99, J. de Physique, Coll., December 1999. http://ipnweb.in2p3.fr/~lptms/membres/brazov

Theory of plastic flows of CDWs in application to the current conversion

We suggest a theoretical picture for distributions of plastic deformations experienced by a sliding Charge Density Wave in the course of the conversion from the normal current at the contact to the collective one in the bulk. Several mechanisms of phase slips via creation and proliferation of dislocations are compared. The results are applied to space resolved X-ray, multi-contact and optical studies. Numerical simulations are combined with model independent relations.Comment: To be published in Proceedings of ECRYS-99, J. de Physique, Coll., December 1999. 7 pages, 3 figure

Topological Defects in Spin Density Waves

The rich order parameter of Spin Density Waves allows for unusual object of a complex topological nature: a half-integer dislocation combined with a semi-vortex of a staggered magnetization. It becomes energetically preferable to ordinary dislocation due to enhanced Coulomb interactions in the semiconducting regime. Generation of these objects changes e.g. the narrow band noise frequency.Comment: 9 pages, 2 figure

Measuring Real Investment: Trends in the United States and International Comparisons

The standard measures of nominal capital formation show the United States investing a proportion of GDP much lower than those of other developed countries throughout the last 25 years and falling further behind over time. In contrast, measures we have calculated in real terms across countries and over time indicate that US investment ratios have been rising over time and have been coming closer and closer to those of the other countries. A broader measure of capital formation more consonant with economic concepts shows the United States to have been close to the other countries since 1970 and to have been investing an above average share of total output in the most recent period 1990-1994. Real capital formation per capita and per worker, even conventionally defined, has been consistently between 15 and 25 percent higher than in the other countries and broadly defined real capital formation per capita and per worker has been 30 to 60 percent higher.

Does the United States invest "too little?"

The standard measures of nominal capital formation show the United States investing a proportion of GDP much lower than those of other developed countries throughout the last 2 years and falling further behind over time. In contrast, measures we have calculated in real terms across and over time indicate that U.S. investment ratios have been rising over time and have been coming closer and closer to those of the other countries. A broader measure of capital formation, more consonant with economic concepts, shows the United States to have been close to the other countries since 1970 and to have been investing an above average share of total output in the most recent period 1990-1994. Real capital formation per capita and per worker, even conventionally defined, have been consistently between 15 and 25 per cent higher than in the other countries and broadly defined real capital formation per capita and per worker have been 30 to 60 percent higher.Capital ; Saving and investment

Observation of correlations up to the micrometer scale in sliding charge-density waves

High-resolution coherent x-ray diffraction experiment has been performed on the charge density wave (CDW) system K$_{0.3}$MoO$_3$. The $2k_F$ satellite reflection associated with the CDW has been measured with respect to external dc currents. In the sliding regime, the $2k_F$ satellite reflection displays secondary satellites along the chain axis which corresponds to correlations up to the micrometer scale. This super long range order is 1500 times larger than the CDW period itself. This new type of electronic correlation seems inherent to the collective dynamics of electrons in charge density wave systems. Several scenarios are discussed.Comment: 4 pages, 3 figures Typos added, references remove

Multi-vortex dynamics in junctions of charge density waves

Ground state reconstruction by creation of topological defects in junctions of CDWs is a convenient playground for modern efforts of field-effect transformations in strongly correlated materials with spontaneous symmetry breakings. Being transient, this effect contributes also to another new science of pump-induced phase transitions. We present a dynamical model for behavior of the CDW in restricted geometries of junctions under an applied voltage or a passing current. The model takes into account multiple interacting fields: the amplitude and the phase of the CDW complex order parameter, distributions of the electric field, the density and the current of various normal carriers. A particular challenge was to monitor the local conservation of the condensed and the normal charge densities. That was done easily invoking the chiral invariance and the associated anomaly, but prize is an unconventional Ginsburg-Landau type theory which is not analytic with respect to the order parameter. The numerical modeling poses unusual difficulties but still can demonstrate that vortices are nucleated at the junction boundary when the voltage across, or the current through, exceed a threshold.Comment: To be published in proceedings of the conference SUPERSTRIPES-2014, A. Bianconi ed., J. Supercond. Nov. Mag., (2015

Electron-phonon and electron-electron interactions in organic field effect transistors

Recent experiments have demonstrated that the performances of organic FETs strongly depend on the dielectric properties of the gate insulator. In particular, it has been shown that the temperature dependence of the mobility evolves from a metallic-like to an insulating behavior upon increasing the dielectric constant of the gate material. This phenomenon can be explained in terms of the formation of small polarons, due to the polar interaction of the charge carriers with the phonons at the organic/dielectric interface. Building on this model, the possible consequences of the Coulomb repulsion between the carriers at high concentrations are analyzed.Comment: proceedings of the SMEC'07 conference, submitted to the Journal of Physics and Chemistry of Solid

Cultural brokering with Syrian refugee families with young children: an exploration of challenges and best practices in psychosocial adaptation

This study examined the challenges and critical psychosocial needs of Syrian refugee families with young children in Western Canada, and the role of cultural brokering in facilitating their psychosocial adaptation. Using a community-based participatory research approach and critical incident method, the study involved nine Arabic-speaking cultural brokers who were working with Syrian refugee families using holistic supports during early resettlement. Data collected through focus groups and semi-structured interviews are presented in five illustrative case studies, and reveal that Syrian families struggled with feeling safe and secure in Canada, adjusting to the changing roles in the family, and trying to find meaning in their lives. These struggles were attributed to families’ overall challenges navigating various domains of integration (i.e., health, social services, and education), resulting in a heavy reliance on cultural brokers for social linking and bonding activities (Ager & Strang, 2008), including connecting families to needed supports and helping family members build relationships with one another. Challenges faced by families mapped onto the five psychosocial needs of Silove’s (2013) Adaptation after Persecution and Trauma (ADAPT) conceptual framework as well as most of the core domains of Ager and Strang’s (2008) Social Integration framework. This study provides evidence for the use of both of these frameworks in further studies involving Syrian refugee populations; they proved useful for understanding how families can develop necessary skills to engage on their own in linking activities with various Canadian institutions and bridging activities with communities at large