24,429 research outputs found
Gender Identities and Feminism
Many feminists (e.g. T. Bettcher and B. R. George) argue for a principle of first person authority (FPA) about gender, i.e. that we should (at least) not disavow people's gender self-categorisations. However, there is a feminist tradition resistant to FPA about gender, which I call "radical feminism”. Feminists in this tradition define gender-categories via biological sex, thus denying non-binary and trans self-identifications. Using a taxonomy by B. R. George, I begin to demystify the concept of gender. We are also able to use the taxonomy to model various feminist approaches. It becomes easier to see how conceptualisations ofgender which allow for FPA often do not allow for understanding female subjugation as being rooted in reproductive biology. I put forward a conceptual scheme: radical FPA feminism. If we accept FPA, but also radical feminist concerns, radical FPA feminism is an attractive way of conceptualising gender
Newly identified lines in NeI isoelectronic sequences
Grazing-incidence spectrometer and low inductance spark source used to study lines of high degrees of ionization of Sc, Ti, and
Sim(2) and SUSY
The proposal of hep-ph/0601236, that the laws of physics in flat spacetime
need be invariant only under a SIM(2) subgroup of the Lorentz group, is
extended to include supersymmetry. SUSY gauge theories which
include SIM(2) couplings for the fermions in chiral multiplets are formulated.
These theories contain two conserved supercharges rather than the usual four.Comment: 10 pages, revtex4. Note added and sign correcte
Electroweak Baryogenesis and Colored Scalars
We consider the 2-loop finite temperature effective potential for a Standard
Model-like Higgs boson, allowing Higgs boson couplings to additional scalars.
If the scalars transform under color, they contribute 2-loop diagrams to the
effective potential that include gluons. These 2-loop effects are perhaps
stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they
can increase the strength of the phase transition by as much as a factor of
3.5. It is the analogue of this effect that is responsible for the survival of
the tenuous electroweak baryogenesis window of the Minimal Supersymmetric
Standard Model. We further illuminate the importance of these 2-loop diagrams
by contrasting models with colored scalars to models with singlet scalars. We
conclude that baryogenesis favors models with light colored scalars. This
motivates searches for pair-produced di-jet resonances or jet(s) + missing
energy.Comment: 12 pages, 5 figures; v2: minor changes, journal versio
Development of strategies to improve quality and safety and reduce cost of production in organic and ‘low input‘ crop production systems
The overall aims of organic and low input crop production include the economically viable and environmentally sound production of high quality food and feed. Technological bottlenecks in such systems include insufficient and instable yields and in some instances unsatisfactory processing, sensory and/or nutritional quality of the final product. Recently, concerns have also been raised that the intensive use of manures may lead to increased risk for contamination of food by enteropathogenic micro-organisms. Crop production in low input systems is based on key pillars, i.e. (i) a fertile soil which provides sufficient capacity to allow for plant growth while preventing soil-borne diseases, (ii) high quality, disease-free seeds and plant material, (iii) a crop-specific soil fertility management to provide sufficient nutrients for optimum plant growth, and (iv) adequate crop protection techniques to prevent damage due to noxious organisms. In the QLIF project we develop improved component strategies to overcome technological bottlenecks in annual (wheat, lettuce, tomato) and perennial (apple) crop production systems. In this paper we report the progress achieved so far
Detecting entanglement of two electron spin qubits with witness operators
We propose a scheme for detecting entanglement between two electron spin
qubits in a double quantum dot using an entanglement witness operator. We first
calculate the optimal configuration of the two electron spins, defined as the
position in the energy level spectrum where, averaged over the nuclear spin
distribution, 1) the probability to have two separated electrons, and 2) the
degree of entanglement of the quantum state quantified by the concurrence are
both large. Using a density matrix approach, we then calculate the evolution of
the expectation value of the witness operator for the two-spin singlet state,
taking into account the effect of decoherence due to quantum charge
fluctuations modeled as a boson bath. We find that, for large interdot
coupling, it is possible to obtain a highly entangled and robust ground state.Comment: 4 pages, 3 figure
Quantum Dissipation due to the Interaction with Chaos
We discuss the possibility of having "quantum dissipation" due to the
interaction with chaotic degrees of freedom. We define the conditions that
should be satisfied in order to have a dissipative effect similar to the one
due to an interaction with a (many body) bath. We also compare with the case
where the environment is modeled by a random matrix model. In case of
interaction with "chaos" we observe a regime where the relaxation process is
non-universal, and reflects the underlaying semiclassical dynamics. As an
example we consider a two level system (spin) that interacts with a two
dimensional anharmonic oscillator.Comment: 5 pages, 1 figure, final improved version, to be published as Phys
Rev. E Rapid Communicatio
Gamma-ray bursts during neutron star formation. Gamma-ray bursts and transient X-ray sources
Discussions are presented of the associations between cosmic gamma ray bursts and transient X-ray sources, and the release of gravitational binding energy during the formation of neutron stars. The model for studying the associations is described along with the release of neutrinos during the collapse of white dwarfs
Effect of random interactions in spin baths on decoherence
We study the decoherence of a central spin 1/2 induced by a spin bath with
intrabath interactions. Since we are interested in the cumulative effect of
interaction and disorder, we study baths comprising Ising spins with random
ferro- and antiferromagnetic interactions between the spins. Using the
resolvent operator method which goes beyond the standard Born-Markov master
equation approach, we show that, in the weak coupling regime, the decoherence
of the central spin at all times is entirely determined by the local-field
distribution or equivalently, the dynamical structure factor of the Ising bath.
We present analytic results for the Ising spin chain bath at arbitrary
temperature for different distributions of the intrabath interaction strengths.
We find clear evidence of non-Markovian behavior in the low temperature regime.
We also consider baths described by Ising models on higher-dimensional
lattices. We find that interactions lead to a significant reduction of the
decoherence. An important feature of interacting spinbaths is the saturation of
the asymptotic Markovian decay rate at high temperatures, as opposed to the
conventional Ohmic boson bath.Comment: 13 page
Entanglement spectroscopy of a driven solid-state qubit and its detector
We study the asymptotic dynamics of a driven quantum two level system coupled
via a quantum detector to the environment. We find multi-photon resonances
which are due to the entanglement of the qubit and the detector. Different
regimes are studied by employing a perturbative Floquet-Born-Markov approach
for the qubit+detector system, as well as non-perturbative real-time path
integral schemes for the driven spin-boson system. We find analytical results
for the resonances, including the red and the blue sidebands. They agree well
with those of exact ab-initio calculations.Comment: 4 pages, 4 figure
- …