31,420 research outputs found
Mathematics Is Physics
In this essay, I argue that mathematics is a natural science---just like
physics, chemistry, or biology---and that this can explain the alleged
"unreasonable" effectiveness of mathematics in the physical sciences. The main
challenge for this view is to explain how mathematical theories can become
increasingly abstract and develop their own internal structure, whilst still
maintaining an appropriate empirical tether that can explain their later use in
physics. In order to address this, I offer a theory of mathematical
theory-building based on the idea that human knowledge has the structure of a
scale-free network and that abstract mathematical theories arise from a
repeated process of replacing strong analogies with new hubs in this network.
This allows mathematics to be seen as the study of regularities, within
regularities, within ..., within regularities of the natural world. Since
mathematical theories are derived from the natural world, albeit at a much
higher level of abstraction than most other scientific theories, it should come
as no surprise that they so often show up in physics.
This version of the essay contains an addendum responding to Slyvia
Wenmackers' essay and comments that were made on the FQXi website.Comment: 15 pages, LaTeX. Second prize winner in 2015 FQXi Essay Contest (see
http://fqxi.org/community/forum/topic/2364
Voltage from mechanical stress in type-II superconductors: Depinning of the magnetic flux by moving dislocations
Mechanical stress causes motion of defects in solids. We show that in a
type-II superconductor a moving dislocation generates a pattern of current that
exerts the depinning force on the surrounding vortex lattice. Concentration of
dislocations and the mechanical stress needed to produce critical depinning
currents are shown to be within practical range. When external magnetic field
and transport current are present this effect generates voltage across the
superconductor. Thus a superconductor can serve as an electrical sensor of the
mechanical stress.Comment: 3 pages, 1 figure
Experimental Studies for the Detection of Protein in Trace Amounts Quarterly Status Report, 1 Mar. - 31 May 1965
Methods for separating inorganic compounds from organic materials in investigation of trace proteins in soil
Polymorphism of the tumor necrosis factor beta gene in systemic lupus erythematosus
We investigated the Nco I restriction fragment
length polymorphism (RFLP) of the tumor necrosis
factor beta (TNFB) gene in 173 patients with systemic
lupus erythematosus (SLE), 192 unrelated
healthy controls, and eleven panel families, all of German
origin. The phenotype frequency of the TNFB*I
allele was significantly increased in patients compared
to controls (63.6% vs 47.1%, RR = 1.96, p <0.002).
The results of a two-point haplotype statistical analysis
between TNFB and HLA alleles show that there is linkage
disequilibrium between TNFB*I and HLA-A1,
Cw7, B8, DR3, DQ2, and C4A DE. The frequency of
TNFB*I was compared in SLE patients and controls in
the presence or absence of each of these alleles.
TNFB*I is increased in patients over controls only in
the presence of the mentioned alleles. Therefore, the
whole haplotypeA1, Cw7, B8, TNFB* I, C4A DE, DR3,
DQ2 is increased in patients and it cannot be determined
which of the genes carried by this haplotype is
responsible for the susceptibility to SLE. In addition,
two-locus associations were analyzed in 192 unrelated
healthy controls for TNFB and class I alleles typed by
serology, and for TNFB and class II alleles typed by
polymerase chain reaction/oligonucleotide probes. We
found positive linkage disequilibrium between
TNFB*I and the following alleles: HLA-A24, HLA-B8,
DRBI*0301, DRBI*ll04, DRBI*1302, DQAI*0501, DQBI*0201, DQBI*0604, and DPBI*OIO1. TNFB*2
is associated with HLA-B7, DRBI*1501, and
DQB I *0602
Phonon-induced relaxation of a two-state system in solids
We study phonon-induced relaxation of quantum states of a particle (e.g.,
electron or proton) in a rigid double-well potential in a solid. Relaxation
rate due to Raman two-phonon processes have been computed. We show that in a
two-state limit, symmetry arguments allow one to express these rates in terms
of independently measurable parameters. In general, the two-phonon processes
dominate relaxation at higher temperature. Due to parity effect in a biased
two-state system, their rate can be controlled by the bias.Comment: 5 PR pages, 1 figur
Clusterization, frustration and collectivity in random networks
We consider the random Erd{\H o}s--R\'enyi network with enhanced
clusterization and Ising spins at the network nodes. Mutually linked
spins interact with energy . Magnetic properties of the system as dependent
on the clustering coefficient are investigated with the Monte Carlo heat
bath algorithm. For the Curie temperature increases from 3.9 to 5.5
when increases from almost zero to 0.18. These results deviate only
slightly from the mean field theory. For the spin-glass phase appears
below ; this temperature decreases with , on the contrary to the
mean field calculations. The results are interpreted in terms of social
systems.Comment: 10 pages, 6 figures; serious change of result
Letters between Albert A. Faurot and William Kerr\u27s secretary
Letters concerning a position in the modern languages department at Utah Agricultural College
- âŠ