3,764 research outputs found
The Minimum-Mass Extrasolar Nebula: In-Situ Formation of Close-In Super-Earths
Close-in super-Earths, with radii R = 2-5 R_Earth and orbital periods P < 100
days, orbit more than half, and perhaps nearly all Sun-like stars in the
universe. We use this omnipresent population to construct the minimum-mass
extrasolar nebula (MMEN), the circumstellar disk of solar-composition solids
and gas from which such planets formed, if they formed near their current
locations and did not migrate. In a series of back-of-the-envelope
calculations, we demonstrate how in-situ formation in the MMEN is fast,
efficient, and can reproduce many of the observed properties of close-in
super-Earths, including their gas-to-rock fractions. Testable predictions are
discussed.Comment: Accepted to MNRAS 2013 March
Note on the Electron Energy Spectrum in the Inner Van Allen Belt
Electron energy spectrum in the inner van allen bel
Planetary image conversion task
The Planetary Image Conversion Task group processed 12,500 magnetic tapes containing raw imaging data from JPL planetary missions and produced an image data base in consistent format on 1200 fully packed 6250-bpi tapes. The output tapes will remain at JPL. A copy of the entire tape set was delivered to US Geological Survey, Flagstaff, Ariz. A secondary task converted computer datalogs, which had been stored in project specific MARK IV File Management System data types and structures, to flat-file, text format that is processable on any modern computer system. The conversion processing took place at JPL's Image Processing Laboratory on an IBM 370-158 with existing software modified slightly to meet the needs of the conversion task. More than 99% of the original digital image data was successfully recovered by the conversion task. However, processing data tapes recorded before 1975 was destructive. This discovery is of critical importance to facilities responsible for maintaining digital archives since normal periodic random sampling techniques would be unlikely to detect this phenomenon, and entire data sets could be wiped out in the act of generating seemingly positive sampling results. Reccomended follow-on activities are also included
The Climate Emergency and the Need for Global Climate Stabilization: The Role of Energy Efficiency in Climate Policy
Global climate change is a worldwide challenge requiring a coordinated, international policy response. However, political pressures and disagreements between developed and developing countries have obstructed past climate negotiations and have stalled the adoption of binding greenhouse gas emission reduction targets. Despite slowmoving international climate negotiations and comprehensive climate policies, many countries have turned to energy efficiency as a politically feasible tool to lower energy use and greenhouse gas emissions. Economists debate the effectiveness of energy efficiency policies due differing perspectives regarding the relationship between energy use and economic growth. Because of this fundamental disagreement, economists often come to different conclusions as to whether energy efficiency routinely leads to either a reduction in energy use or leads to an economy-wide increase in energy use. Even when accounting for the rebound effect, many studies indicate that energy efficiency remains a highly cost-effective energy resource in the near future. Energy efficiency policies also offer an immediate and politically feasible policy tool to encourage the adoption of more comprehensive climate policies
Superconducting Plate in Transverse Magnetic Field: New State
A model to describe Cooper pairs near the transition point (on temperature
and magnetic field), when the distance between them is big compared to their
sizes, is proposed. A superconducting plate whose thickness is less than the
pair size in the transverse magnetic field near the critical value is
considered as an application of the model. A new state that is energetically
more favourable than that of Abrikosov vortex state within an interval near the
transition point was obtained. The system's wave function in this state looks
like that of Laughlin's having been used in fractional quantum Hall effect
(naturally, in our case - for Cooper pairs as Bose-particles) and it
corresponds to homogeneous incompressible liquid. The state energy is
proportional to the first power of value , unlike the vortex
state energy having this value squared. The interval of the new state existence
is greater for dirty specimens.Comment: 7 page
Kinetic Approach to Fractional Exclusion Statistics
We show that the kinetic approach to statistical mechanics permits an elegant
and efficient treatment of fractional exclusion statistics. By using the
exclusion-inclusion principle recently proposed [Phys. Rev. E49, 5103 (1994)]
as a generalization of the Pauli exclusion principle, which is based on a
proper definition of the transition probability between two states, we derive a
variety of different statistical distributions interpolating between bosons and
fermions. The Haldane exclusion principle and the Haldane-Wu fractional
exclusion statistics are obtained in a natural way as particular cases. The
thermodynamic properties of the statistical systems obeying the generalized
exclusion-inclusion principle are discussed.Comment: 6 pages, REVTE
Position location and data collection system and method Patent
Development of telemetry system for position location and data acquisitio
Pairing via Index theorem
This work is motivated by a specific point of view: at short distances and
high energies the undoped and underdoped cuprates resemble the -flux phase
of the t-J model. The purpose of this paper is to present a mechanism by which
pairing grows out of the doped -flux phase. According to this mechanism
pairing symmetry is determined by a parameter controlling the quantum tunneling
of gauge flux quanta. For zero tunneling the symmetry is ,
while for large tunneling it is . A zero-temperature critical
point separates these two limits
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