34 research outputs found
A multibaker map for shear flow and viscous heating
A consistent description of shear flow and the accompanied viscous heating as
well the associated entropy balance is given in the framework of a
deterministic dynamical system. A laminar shear flow is modeled by a
Hamiltonian multibaker map which drives velocity and temperature fields. In an
appropriate macroscopic limit one recovers the Navier-Stokes and heat
conduction equations along with the associated entropy balance. This indicates
that results of nonequilibrium thermodynamics can be described by means of an
abstract, sufficiently chaotic and mixing dynamics. A thermostating algorithm
can also be incorporated into this framework.Comment: 11 pages; RevTex with multicol+graphicx packages; eps-figure
First order transition from correlated electron semiconductor to ferromagnetic metal in single crystalline FeSi1-xGex
The phase diagram of FeSi1-xGex, obtained from magnetic, thermal and
transport measurements on single crystals, shows a first-order transition from
a correlated electron semiconductor to a ferromagnetic metal at a critical
concentration, x ~ 0.25. The gap of the insulating phase strongly decreases
with x. The specific heat coefficient appears to track the density of states of
a Kondo insulator. The phase diagram is consistent with a correlation induced
insulator-metal transition in conjunction with disorder on the Si/Ge ligand
site
The history of attention deficit hyperactivity disorder
The contemporary concept of attention deficit hyperactivity disorder (ADHD) as defined in the DSM-IV-TR (American Psychiatric Association 2000) is relatively new. Excessive hyperactive, inattentive, and impulsive children have been described in the literature since the nineteenth century. Some of the early depictions and etiological theories of hyperactivity were similar to current descriptions of ADHD. Detailed studies of the behavior of hyperactive children and increasing knowledge of brain function have changed the concepts of the fundamental behavioral and neuropathological deficits underlying the disorder. This article presents an overview of the conceptual history of modern-day ADHD
EVOLUTION OF A METALLIC AND MAGNETIC STATE IN (Fe, Mn)Si AND Fe(Si, Ge)
An analysis of the pressure-dependent resistivity of FexMn1-xSi(1 less than or equal to x less than or equal to 0.82) and FeSixGe1-x (1 less than or equal to x less than or equal to 0.6) alloys in terms of a Kondo insulator description revealed a pressure-induced opening of the narrow gap. A negative magnetoresistance is observed for Fe-rich alloys of FexMn1-xSi at elevated temperatures