2,661 research outputs found
Extended two-level quantum dissipative system from bosonization of the elliptic spin-1/2 Kondo model
We study the elliptic spin-1/2 Kondo model (spin-1/2 fermions in one
dimension with fully anisotropic contact interactions with a magnetic impurity)
in the light of mappings to bosonic systems using the fermion-boson
correspondence and associated unitary transformations. We show that for fixed
fermion number, the bosonic system describes a two-level quantum dissipative
system with two noninteracting copies of infinitely-degenerate upper and lower
levels. In addition to the standard tunnelling transitions, and the transitions
driven by the dissipative coupling, there are also bath-mediated transitions
between the upper and lower states which simultaneously effect shifts in the
horizontal degeneracy label. We speculate that these systems could provide new
examples of continuous time quantum random walks, which are exactly solvable.Comment: 7 pages, 1 figur
Axonal amyloid precursor protein and its fragments undergo somatodendritic endocytosis and processing.
Deposition of potentially neurotoxic Aβ fragments derived from amyloid precursor protein (APP) at synapses may be a key contributor to Alzheimer's disease. However, the location(s) of proteolytic processing and subsequent secretion of APP fragments from highly compartmentalized, euploid neurons that express APP and processing enzymes at normal levels is not well understood. To probe the behavior of endogenous APP, particularly in human neurons, we developed a system using neurons differentiated from human embryonic stem cells, cultured in microfluidic devices, to enable direct biochemical measurements from axons. Using human or mouse neurons in these devices, we measured levels of Aβ, sAPPα, and sAPPβ secreted solely from axons. We found that a majority of the fragments secreted from axons were processed in the soma, and many were dependent on somatic endocytosis for axonal secretion. We also observed that APP and the β-site APP cleaving enzyme were, for the most part, not dependent on endocytosis for axonal entry. These data establish that axonal entry and secretion of APP and its proteolytic processing products traverse different pathways in the somatodendritic compartment before axonal entry
Report of the calibration of Armco metergates model no. 101
CER47-52SDR11.Prepared for Armco Drainage and Metal Products, Inc., Hardesty Division.January 1951
Analysis of results of rain making projects in the western states
CER47-52SDR-37.In view of the findings of impartial agencies evaluating cloud seeding experiments and in view of the lack of understanding of cloud physics processes which are significant in weather control, for example, the contrary theories as to rain drop formation or as to whether there is a lack of ice crystals or an over-abundance of ice crystals in many cloud formations , a justifiable conclusion is that although cloud seeding probably has had some effect on precipitation, the effect has been on too small a scale to detect and the hopes of the public, fanned on by over-optimistic statements in the public press, have not been realized. However the results to date warrant full scale applied and theoretical experimentation both in the laboratory and in the field on cloud physics and the artificial stimulation of precipitation to determine the most favorable procedures and conditions for cloud seeding and to determine with any assurance the economical value of cloud seeding
Confirmation of a cluster of galaxies hidden behind the Galactic bulge using the VVV Survey
Suzaku and Chandra X-ray observations detected a new cluster of galaxies,
Suzaku J1759-3450, at a redshift z=0.13. It is located behind the Milky Way,
and the high Galactic dust extinction renders it nearly invisible at optical
wavelengths. We attempt here to confirm the galaxy cluster with near-infrared
imaging observations, and to characterize its central member galaxies. Images
from the VVV survey were used to detect candidate member galaxies of Suzaku
J1759-3450 within the central region of the cluster, up to 350 kpc from the
X-ray peak emission. Color-magnitude and color-color diagrams and morphology
criteria allowed us to select the galaxies among the numerous foreground
sources. Fifteen candidate cluster members were found very close to a modeled
red-sequence at the redshift of the cluster. Five members are extremely bright,
and one is possibly a cD galaxy. The asymmetry in the spatial distribution of
the galaxies respect to the X-ray peak emission is an indicator of that this
cluster is still suffering a virialization process. Our investigation of Suzaku
J1759-3450 demonstrates the potential of the VVV Survey to study the hidden
population of galaxies in the Zone of Avoidance.Comment: 7 pages, 5 figures. Accepted for Publication in Astronomy &
Astrophysic
In Re Estate of Ferdinand E. Marcos Human Rights Litigation: a Personal Account of the Role of the Special Master
Report on hydraulic model tests for Rihand Dam
CER47-52SDR5.April 1950.Includes bibliographical references.At head of title: United Province, India, Public Works Department, Irrigation Branch
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