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Implementation of a station/network interface for a CAMB tree network
Packet collisions and their resolution create a performance bottleneck in random-access LANs. A hardware solution to this problem is to use collision avoidance switches. These switches allow the implementation of random access protocols without the penalty of collisions among packets. An architecture based on collision avoidance is the CAMB (Collision Avoidance Multiple Broadcast) tree network, where concurrent broadcasts are possible.This paper is a companion to an earlier report. "TTL Implementations of a CAMB Tree Switch," where a tree network architecture was described for two different implementations of a CAMB tree switch. In the pages that follow, a hardware implementation of the interface between the network stations and the packet switches is proposed. This implementation is based on the first switch design in the companion paper
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TTL implementation of a CAMB tree network switch
Packet collisions and their resolution create a performance bottleneck in random-access LANs. A hardware solution to this problem is to use a collision avoidance switch. These switches allow the implementation of random access protocols without the penalty of collisions among packets. An architecture based on collision avoidance is the CAMB (Collision Avoidance Multiple Broadcast) Tree network, where concurrent broadcasts are possible.The purpose of this paper is to present two implementations for a CAMB Tree switch. First, a general outline of the CAMB switch is provided. Then, a description of the two implementations is given
Evolution and nucleosynthesis of extremely metal-poor and metal-free low- and intermediate-mass stars II. s-process nucleosynthesis during the core He flash
Models of primordial and hyper-metal-poor stars with masses similar to the
Sun experience an ingestion of protons into the hot core during the core helium
flash phase at the end of their red giant branch evolution. This produces a
concurrent secondary flash powered by hydrogen burning that gives rise to
further nucleosynthesis in the core. We perform post-process nucleosynthesis
calculations on a one-dimensional stellar evolution calculation of a star of 1
solar mass and metallicity [Fe/H] = -6.5 that suffers a proton ingestion
episode. Our network includes 320 nuclear species and 2,366 reactions and
treats mixing and burning simultaneously. The mixing and burning of protons
into the hot convective core leads to the production of 13C, which then burns
via the 13C(alpha,n)16O reaction releasing a large number of free neutrons.
During the first two years of neutron production the neutron poison 14N
abundance is low, allowing the prodigious production of heavy elements such as
strontium, barium, and lead via slow neutron captures (the s process). These
nucleosynthetic products are later mixed to the stellar surface and ejected via
stellar winds. We compare our results with observations of the hyper-metal-poor
halo star HE 1327-2326, which shows a strong Sr overabundance. Our model
provides the possibility of self-consistently explaining the Sr overabundance
in HE 1327-2326 together with its C, N, and O overabundances (all within a
factor of ~4) if the material were heavily diluted, for example, via mass
transfer in a wide binary system. The model produces at least 18 times too much
Ba than observed, but this may be within the large modelling uncertainties. In
this scenario, binary systems of low mass must have formed in the early
Universe. If true then this puts constraints on the primordial initial mass
function.Comment: Accepted for publication on Astronomy & Astrophysics Letter
A Novel Protocol-Authentication Algorithm Ruling Out a Man-in-the-Middle Attack in Quantum Cryptography
In this work we review the security vulnerability of Quantum Cryptography
with respect to "man-in-the-middle attacks" and the standard authentication
methods applied to counteract these attacks. We further propose a modified
authentication algorithm which features higher efficiency with respect to
consumption of mutual secret bits.Comment: 4 pages, submitted to the International Journal of Quantum
Information, Proceedings of the meeting "Foundations of Quantum Information",
Camerino, April 200
Learning Financial Shocks and the Great Recession
This paper develops a simple business-cycle model in which financial shocks have large macroeconomic effects when private agents are gradually learning the uncertain environment. When agents update their beliefs about the parameters that govern the unobserved process driving financial shocks to the leverage ratio, the responses of output, investment, and other aggregates under adaptive learning are significantly larger than under rational expectations. In our benchmark case calibrated using US data on leverage, debt-to-GDP and land value-to- GDP ratios for 1996Q1-2008Q4, learning amplifies leverage shocks by a factor of about three, relative to rational expectations. When fed with actual leverage innovations observed over that period, the learning model predicts that the persistence of leverage shocks is increasingly overestimated after 2002 and that a sizeable recession occurs in 2008-10, while its rational expectations counterpart predicts a counter-factual expansion. In addition, we show that procyclical leverage reinforces the amplification due to learning and, accordingly, that macro-prudential policies that enforce countercyclical leverage dampen the effects of leverage shocks
Electron-induced proton knockout from neutron rich nuclei
We study the evolution of the \eep cross section on nuclei with increasing
asymmetry between the number of neutrons and protons. The calculations are done
within the framework of the nonrelativistic and relativistic distorted-wave
impulse approximation. In the nonrelativistic model phenomenological
Woods-Saxon and Hartree-Fock wave functions are used for the proton bound-state
wave functions, in the relativistic model the wave functions are solutions of
Dirac-Hartree equations. The models are first tested against experimental data
on Ca and Ca nuclei, and then they are applied to a set of
spherical calcium isotopes.Comment: 5 pages, 2 figures. contribution to the XIX International School on
Nuclear Physics, Neutron Physics and Applications, Varna (Bulgaria) September
19-25, 201
Electron scattering in isotonic chains as a probe of the proton shell structure of unstable nuclei
Electron scattering on unstable nuclei is planned in future facilities of the
GSI and RIKEN upgrades. Motivated by this fact, we study theoretical
predictions for elastic electron scattering in the N=82, N=50, and N=14
isotonic chains from very proton-deficient to very proton-rich isotones. We
compute the scattering observables by performing Dirac partial-wave
calculations. The charge density of the nucleus is obtained with a covariant
nuclear mean-field model that accounts for the low-energy electromagnetic
structure of the nucleon. For the discussion of the dependence of scattering
observables at low-momentum transfer on the gross properties of the charge
density, we fit Helm model distributions to the self-consistent mean-field
densities. We find that the changes shown by the electric charge form factor
along each isotonic chain are strongly correlated with the underlying proton
shell structure of the isotones. We conclude that elastic electron scattering
experiments in isotones can provide valuable information about the filling
order and occupation of the single-particle levels of protons.Comment: 13 pages; 19 figure
Si/Ge hole-tunneling double-barrier resonant tunneling diodes formed on sputtered flat Ge layers
We have demonstrated Si/Ge hole-tunneling double-barrier resonant tunneling diodes (RTDs) formed on flat Ge layers with a relaxation rate of 89% by our proposed method; in this method, the flat Ge layers can be directly formed on highly B-doped Si(001) substrates using our proposed sputter epitaxy method. The RTDs exhibit clear negative differential resistance effects in the static current–voltage (I–V) curves at room temperature. The quantized energy level estimation suggests that resonance peaks that appeared in the I–V curves are attributed to hole tunneling through the first heavy- and light-hole energy levels
Quantum Interference between a Single-Photon Fock State and a Coherent State
We derive analytical expressions for the single mode quantum field state at
the individual output ports of a beam splitter when a single-photon Fock state
and a coherent state are incident on the input ports. The output states turn
out to be a statistical mixture between a displaced Fock state and a coherent
state. Consequently we are able to find an analytical expression for the
corresponding Wigner function. Because of the generality of our calculations
the obtained results are valid for all passive and lossless optical four port
devices. We show further how the results can be adapted to the case of the
Mach-Zehnder interferometer. In addition we consider the case for which the
single-photon Fock state is replaced with a general input state: a coherent
input state displaces each general quantum state at the output port of a beam
splitter with the displacement parameter being the amplitude of the coherent
state.Comment: 9 pages, 6 figure
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