21,714 research outputs found
Privacy, Public Goods, and the Tragedy of the Trust Commons: A Response to Professors Fairfield and Engel
User trust is an essential resource for the information economy. Without it, users would not provide their personal information and digital businesses could not operate.
Digital companies do not protect this trust sufficiently. Instead, many take advantage of it for short-term gain. They act in ways that, over time, will undermine user trust. In so doing, they act against their own best interest.
This Article shows that companies behave this way because they face a tragedy of the commons. When a company takes advantage of user trust for profit, it appropriates the full benefit of this action. However, it shares the cost with all other companies that rely on the wellspring of user trust. Each company, acting rationally, has an incentive to appropriate as much of the trust resource as it can. That is why such companies collect, analyze, and “monetize” our personal information in such an unrestrained way.
This behavior poses a longer term risk. User trust is like a fishery. It can withstand a certain level of exploitation and renew itself. But over-exploitation can cause it to collapse. Were digital companies collectively to undermine user trust this would not only hurt the users, it would damage the companies themselves. This Article explores commons-management theory for potential solutions to this impending tragedy of the trust commons
Txt2vz: a new tool for generating graph clouds
We present txt2vz (txt2vz.appspot.com), a new tool for automatically generating a visual summary of unstructured text data found in documents or web sites. The main purpose of the tool is to give the user information about the text so that they can quickly get a good idea about the topics covered. Txt2vz is able to identify important concepts from unstructured text data and to reveal relationships between those concepts. We discuss other approaches to generating diagrams from text and highlight the differences between tag clouds, word clouds, tree clouds and graph clouds
Superconductivity from Undressing. II. Single Particle Green's Function and Photoemission in Cuprates
Experimental evidence indicates that the superconducting transition in high
cuprates is an 'undressing' transition. Microscopic mechanisms giving
rise to this physics were discussed in the first paper of this series. Here we
discuss the calculation of the single particle Green's function and spectral
function for Hamiltonians describing undressing transitions in the normal and
superconducting states. A single parameter, , describes the strength
of the undressing process and drives the transition to superconductivity. In
the normal state, the spectral function evolves from predominantly incoherent
to partly coherent as the hole concentration increases. In the superconducting
state, the 'normal' Green's function acquires a contribution from the anomalous
Green's function when is non-zero; the resulting contribution to
the spectral function is for hole extraction and for hole
injection. It is proposed that these results explain the observation of sharp
quasiparticle states in the superconducting state of cuprates along the
direction and their absence along the direction.Comment: figures have been condensed in fewer pages for easier readin
Collider signals of gravitino dark matter in bilinearly broken R-parity
In models with gauge mediated supersymmetry breaking the gravitino is the
lightest supersymmetric particle. If R-parity is violated the gravitino decays,
but with a half-live far exceeding the age of the universe and thus is, in
principle, a candidate for the dark matter. We consider the decays of the
next-to-lightest supersymmetric particle, assumed to be the neutralino. We show
that in models where the breaking of R-parity is bilinear, the condition that
R-parity violation explains correctly the measured neutrino masses fixes the
branching ratio of the decay in the
range , if the gravitino mass is in the range required to
solve the dark matter problem, i.e. of the order (few) 100 eV. This scenario is
therefore directly testable at the next generation of colliders.Comment: 13 pages, 3 figure
Superconductivity from Undressing
Photoemission experiments in high cuprates indicate that quasiparticles
are heavily 'dressed' in the normal state, particularly in the low doping
regime. Furthermore these experiments show that a gradual undressing occurs
both in the normal state as the system is doped and the carrier concentration
increases, as well as at fixed carrier concentration as the temperature is
lowered and the system becomes superconducting. A similar picture can be
inferred from optical experiments. It is argued that these experiments can be
simply understood with the single assumption that the quasiparticle dressing is
a function of the local carrier concentration. Microscopic Hamiltonians
describing this physics are discussed. The undressing process manifests itself
in both the one-particle and two-particle Green's functions, hence leads to
observable consequences in photoemission and optical experiments respectively.
An essential consequence of this phenomenology is that the microscopic
Hamiltonians describing it break electron-hole symmetry: these Hamiltonians
predict that superconductivity will only occur for carriers with hole-like
character, as proposed in the theory of hole superconductivity
The Brazilian Soybean Complex
Crop Production/Industries, Q13, O54, Q56, 013,
Mixed triplet and singlet pairing in multicomponent ultracold fermion systems with dipolar interactions
The symmetry properties of the Cooper pairing problem for multi-component
ultra-cold dipolar molecular systems are investigated. The dipolar anisotropy
provides a natural and robust mechanism for both triplet and singlet Cooper
pairing to first order in the interaction strength. With a purely dipolar
interaction, the triplet -like polar pairing is the most dominant. A
short-range attractive interaction can enhance the singlet pairing to be nearly
degenerate with the triplet pairing. We point out that these two pairing
channels can mix by developing a relative phase of , thus
spontaneously breaking time-reversal symmetry. We also suggest the possibility
of such mixing of triplet and singlet pairing in other systems.Comment: accepted by Phys. Rev.
Compressible Flows in Fluidic Oscillators
We present qualitative observations on the internal flow characteristics of
fluidic oscillator geometries commonly referred to as sweeping jets in active
flow control applications. This is part of the fluid dynamics videos.Comment: Videos include
Proposal for a Supersymmetric Standard Model
The fact that neutrinos are massive suggests that the minimal supersymmetric
standard model (MSSM) might be extended in order to include three gauge-singlet
neutrino superfields with Yukawa couplings of the type . We
propose to use these superfields to solve the problem of the MSSM without
having to introduce an extra singlet superfield as in the case of the
next-to-MSSM (NMSSM). In particular, terms of the type in the
superpotential may carry out this task spontaneously through sneutrino vacuum
expectation values. In addition, terms of the type avoid the
presence of axions and generate effective Majorana masses for neutrinos at the
electroweak scale. On the other hand, these terms break lepton number and
R-parity explicitly implying that the phenomenology of this model is very
different from the one of the MSSM or NMSSM. For example, the usual neutralinos
are now mixed with the neutrinos. For Dirac masses of the latter of order
GeV, eigenvalues reproducing the correct scale of neutrino masses are
obtained.Comment: 9 pages, latex, title modified. Final version published in PR
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