8,051 research outputs found
Time-resolved Observation and Control of Superexchange Interactions with Ultracold Atoms in Optical Lattices
Quantum mechanical superexchange interactions form the basis of quantum
magnetism in strongly correlated electronic media. We report on the direct
measurement of superexchange interactions with ultracold atoms in optical
lattices. After preparing a spin-mixture of ultracold atoms in an
antiferromagnetically ordered state, we measure a coherent
superexchange-mediated spin dynamics with coupling energies from 5 Hz up to 1
kHz. By dynamically modifying the potential bias between neighboring lattice
sites, the magnitude and sign of the superexchange interaction can be
controlled, thus allowing the system to be switched between antiferromagnetic
or ferromagnetic spin interactions. We compare our findings to predictions of a
two-site Bose-Hubbard model and find very good agreement, but are also able to
identify corrections which can be explained by the inclusion of direct
nearest-neighbor interactions.Comment: 24 pages, 7 figure
Gravity a la Born-Infeld
A simple technique for the construction of gravity theories in Born-Infeld
style is presented, and the properties of some of these novel theories are
investigated. They regularize the positive energy Schwarzschild singularity,
and a large class of models allows for the cancellation of ghosts. The possible
correspondence to low energy string theory is discussed. By including curvature
corrections to all orders in alpha', the new theories nicely illustrate a
mechanism that string theory might use to regularize gravitational
singularities.Comment: 21 pages, 2 figures, new appendix B with corrigendum: Class. Quantum
Grav. 21 (2004) 529
Loudly sing cuckoo : More-than-human seasonalities in Britain
This research was funded by a grant from the Arts and Humanities Research Council, grant number AH/E009573/1.Peer reviewedPostprin
Do Financial Incentives Encourage Women to Apply for a Tech Job? Evidence from a Natural Field Experiment
This is the final version. Available from the American Economic Association via the DOI in this recordWe conduct a natural field experiment to test whether offering financial incentives encourages more female job seekers to complete their applications for a tech job. All eligible applicants for the job were invited to perform an online skill assessment. We randomized whether or not they were offered an incentive of up to $10 for completing the assessment. We find no significant effect of the incentive for female applicants (or male applicants).Australian Research Council (ARC
Validation of Kalman Filter alignment algorithm with cosmic-ray data using a CMS silicon strip tracker endcap
A Kalman Filter alignment algorithm has been applied to cosmic-ray data. We
discuss the alignment algorithm and an experiment-independent implementation
including outlier rejection and treatment of weakly determined parameters.
Using this implementation, the algorithm has been applied to data recorded with
one CMS silicon tracker endcap. Results are compared to both photogrammetry
measurements and data obtained from a dedicated hardware alignment system, and
good agreement is observed.Comment: 11 pages, 8 figures. CMS NOTE-2010/00
Does Arbitration Blossom When State Courts are Bad?
It is often conjectured that non-state dispute resolution blossoms when state courts are not independent or are perceived as low-quality courts. This conjecture implies a substitutive relationship between state and non-state dispute resolution. An alternative hypothesis argues that both the quality and the frequency of use of these two alternative mechanisms are complementary: societies with high-quality state courts would also be able to provide high-quality non-state dispute resolution. This is the first study that puts these hypotheses to an empirical test. It turns out that the lower the perceived quality of state courts, the less frequently conflicting firms resort to them. Second, firms in common-law countries turn away from state courts significantly more often than firms in civil-law countries. This result sheds doubt on the robustness of results generated within the legal traditions literature. Finally, in states that have created the preconditions for arbitration, businesspeople resort significantly more often to state courts. We interpret this as evidence in favor of the complementarity hypothesis
ATLAS silicon module assembly and qualification tests at IFIC Valencia
ATLAS experiment, designed to probe the interactions of particles emerging
out of proton proton collisions at energies of up to 14 TeV, will assume
operation at the Large Hadron Collider (LHC) at CERN in 2007. This paper
discusses the assembly and the quality control tests of forward detector
modules for the ATLAS silicon microstrip detector assembled at the Instituto de
Fisica Corpuscular (IFIC) in Valencia. The construction and testing procedures
are outlined and the laboratory equipment is briefly described. Emphasis is
given on the module quality achieved in terms of mechanical and electrical
stability.Comment: 23 pages, 38 EPS figures, uses JINST LaTeX clas
Examining the Connections within the Startup Ecosystem: A Case Study of St. Louis
This paper documents the resurgence of entrepreneurial activity in St. Louis by reporting on the collaboration and local learning within the startup community. This activity is happening both between entrepreneurs and between organizations that provide support, such as mentoring and funding, to entrepreneurs. As these connections deepen, the strength of the entrepreneurial ecosystem grows. Another finding from the research is that activity-based events, where entrepreneurs have the chance to use and practice the skills needed to grow their businesses, are most useful. St. Louis provides a multitude of these activities, such as Startup Weekend, 1 Million Cups, Code Until Dawn, StartLouis, and GlobalHack. Some of these are St. Louis specific, but others have nationwide or global operations, providing important implications for other cities
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