Chaos and Universality in a Four-Dimensional Spin Glass

We present a finite size scaling analysis of Monte Carlo simulation results on a four dimensional Ising spin glass. We study chaos with both coupling and temperature perturbations, and find the same chaos exponent in each case. Chaos is investigated both at the critical temperature and below where it seems to be more efficient (larger exponent). Dimension four seems to be above the critical dimension where chaos with temperature is no more present in the critical region. Our results are consistent with the Gaussian and bimodal coupling distributions being in the same universality class.Comment: 11 pages, including 6 postscript figures. Latex with revtex macro

Structural, chemical and magnetic properties of secondary phases in Co-doped ZnO

We have utilized a comprehensive set of experimental techniques such as transmission electron microscopy (TEM) and synchrotron-based x-ray absorption spectroscopy (XAS) and the respective x-ray linear dichroism and x-ray magnetic circular dichroism to characterize the correlation of structural, chemical and magnetic properties of Co-doped ZnO samples. It can be established on a quantitative basis that the superparamagnetic (SPM) behavior observed by integral superconducting quantum interference device magnetometry is not an intrinsic property of the material but stems from precipitations of metallic Co. Their presence is revealed by TEM as well as XAS. Annealing procedures for these SPM samples were also studied, and the observed changes in the magnetic properties found to be due to a chemical reduction or oxidation of the metallic Co species

Chaos in a Two-Dimensional Ising Spin Glass

We study chaos in a two dimensional Ising spin glass by finite temperature Monte Carlo simulations. We are able to detect chaos with respect to temperature changes as well as chaos with respect to changing the bonds, and find that the chaos exponents for these two cases are equal. Our value for the exponent appears to be consistent with that obtained in studies at zero temperature.Comment: 4 pages, LaTeX, 4 postscript figures included. The analysis of the data is now done somewhat differently. The results are consistent with the chaos exponent found at zero temperature. Additional papers of PY can be obtained on-line at http://schubert.ucsc.edu/pete

Critical reflection in practice: Generating Knowledge from the Interactions with Promotores for Engagement in Neurocognitive Disorders

Background: Colonias are underserved areas along the Texas-Mexico border, with high incidences of neurocognitive disorders, dementia, and Alzheimer\u27s disease (AD). Our goal is to build capacity to reduce risk, facilitate treatment for affected individuals, and provide caregiver support. Our aim was to construct an approach that was reflective and would reveal the rich and diverse ways in which people make meaning of their experiences and interactions with scientists, faculty, staff and students. Methods: We examined our work with local community health workers. (CHWs), promotores in Spanish, to establish contact with, engage, mobilize, and educate the Hispanic communities of the Lower Rio Grande Valley (LRGV). Qualitative research methods were the principal way to approach this aim, including critical reflection. Results: We now have 347 certified promotores in LRGV: 174 in Cameron County, 169 in Hidalgo County, 3 in Starr County, and 1 in Willacy County. Most of the promotores in LRGV are female, Spanish-speakers (98%) although half of them are also fluent in English and more than half of the promotores have five years or more as a state-certified CHW. Assumptions about knowledge, power and reflexivity surfaced in the interactions with members of the academic world interacting with Colonia’s residents. Conclusions: Aspects of critical reflection, including deconstructing assumptions about knowledge, power and reflexivity, are useful to guide actions that facilitate capacity building in the Colonias, as well as action research methodology. The LRGV population’s characteristics make early detection of AD and dementia and support for patients and caregivers’ high priorities and clearly understanding the role of promotores as mediators is important

MOTIM – An Industrial Application Using NOCs

High-speed networks used to interconnect computers advance at an extraordinary pace, driven by the evolution of several contributing technologies. Due to the ever-increasing complexity of designing parts and equipments for these networks, design complexity management makes scalability and reusability more important issues than performance, in most cases. This paper describes MOTIM, a scalable and reusable architecture enabling the implementation of Ethernet switches with low latency and high throughput. The architecture is built around a network-on-chip-based switch fabric, which guarantees scalability. The architecture has been validated by functional simulation and prototyped in FPGAs. The experimental results show that even under severe traffic conditions the architecture achieves packet transmission with low latencies. Categories and Subject Descriptor

Structure and peculiarities of the (8 x n)-type Si(001) surface prepared in a molecular-beam epitaxy chamber: a scanning tunneling microscopy study

A clean Si(001) surface thermally purified in an ultrahigh vacuum molecular-beam epitaxy chamber has been investigated by means of scanning tunneling microscopy. The morphological peculiarities of the Si(001) surface have been explored in detail. The classification of the surface structure elements has been carried out, the dimensions of the elements have been measured, and the relative heights of the surface relief have been determined. A reconstruction of the Si(001) surface prepared in the molecular-beam epitaxy chamber has been found to be (8 x n). A model of the Si(001)-(8 x n) surface structure is proposed.Comment: 4 pages, 8 figures. Complete versio

On chaos in mean field spin glasses

We study the correlations between two equilibrium states of SK spin glasses at different temperatures or magnetic fields. The question, presiously investigated by Kondor and Kondor and V\'egs\"o, is approached here constraining two copies of the same system at different external parameters to have a fixed overlap. We find that imposing an overlap different from the minimal one implies an extensive cost in free energy. This confirms by a different method the Kondor's finding that equilibrium states corresponding to different values of the external parameters are completely uncorrelated. We also consider the Generalized Random Energy Model of Derrida as an example of system with strong correlations among states at different temperatures.Comment: 19 pages, Late

Numerical Study of Spin and Chiral Order in a Two-Dimensional XY Spin Glass

The two dimensional XY spin glass is studied numerically by a finite size scaling method at T=0 in the vortex representation which allows us to compute the exact (in principle) spin and chiral domain wall energies. We confirm earlier predictions that there is no glass phase at any finite T. Our results strongly support the conjecture that both spin and chiral order have the same correlation length exponent $\nu \approx 2.70$. We obtain preliminary results in 3d.Comment: 4 pages, 2 figures, revte