3,799 research outputs found
Two-Photon Spectroscopy of the NaLi Triplet Ground State
We employ two-photon spectroscopy to study the vibrational states of the
triplet ground state potential () of the NaLi
molecule. Pairs of Na and Li atoms in an ultracold mixture are photoassociated
into an excited triplet molecular state, which in turn is coupled to
vibrational states of the triplet ground potential. Vibrational state binding
energies, line strengths, and potential fitting parameters for the triplet
ground potential are reported. We also observe rotational
splitting in the lowest vibrational state.Comment: 7 pages, 3 figure
A Storm in a "T" Cup
We revisit the process of transversification and agglomeration of particle
momenta that are often performed in analyses at hadron colliders, and show that
many of the existing mass-measurement variables proposed for hadron colliders
are far more closely related to each other than is widely appreciated, and
indeed can all be viewed as a common mass bound specialized for a variety of
purposes.Comment: 3 pages, 2 figures, presented by K.C. Kong at the 19th Particles and
Nuclei International Conference, PANIC 2011, MIT, Cambridge, MA (July 24-29,
2011
Why Private Labels Show Long-Term Market Share Evolution
Previous research has shown that most consumer packaged goods markets are in long-run competitive equilibrium. In most categories, a given brand’s market share is stationary, showing remarkable stability over long time horizons (10 years). This empirical generalization has been attributed to consumer inertia and to competitive reaction elasticities that lead to offsetting marketing spending which nullify attempts by one brand to take unilateral action to increase share. We find a clear exception to this rule — during the period 1987-94 the retailer’s private label consistently showed positive market share evolution. In 225 consumer packaged goods categories, private labels trended upward 86% of the time. The trend persisted even after controlling for marketing spending by both national and store brands. We consider the viability of alternative explanations including changes in consumer and national brand behavior and find that none of them can adequately account for the trend in private label share. We offer an analytical explanation and empirical support for why private labels can grow even though national brands shares are relatively stable. We argue that the retailer is in the best position to opportunistically appropriate different sources of category growth because not only does it control it own marketing spending, it also exerts some influence over the ultimate marketplace spending of their national brand competitors
Photoassociation of Ultracold NaLi
We perform photoassociation spectroscopy in an ultracold Na-Li
mixture to study the excited triplet molecular potential. We
observe 50 vibrational states and their substructure to an accuracy of 20 MHz,
and provide line strength data from photoassociation loss measurements. An
analysis of the vibrational line positions using near-dissociation expansions
and a full potential fit is presented. This is the first observation of the
potential, as well as photoassociation in the NaLi system.Comment: 6 pages, 3 figure
Long-Lived Ultracold Molecules with Electric and Magnetic Dipole Moments
We create fermionic dipolar NaLi molecules in their triplet ground
state from an ultracold mixture of Na and Li. Using
magneto-association across a narrow Feshbach resonance followed by a two-photon
STIRAP transfer to the triplet ground state, we produce
ground state molecules in a spin-polarized state. We observe a lifetime of
in an isolated molecular sample, approaching the -wave
universal rate limit. Electron spin resonance spectroscopy of the triplet state
was used to determine the hyperfine structure of this previously unobserved
molecular state.Comment: 5 pages, 5 figure
Collisional Cooling of Ultracold Molecules
Since the original work on Bose-Einstein condensation, quantum degenerate
gases of atoms have allowed the quantum emulation of important systems from
condensed matter and nuclear physics, as well as the study of novel many-body
states with no analog in other fields of physics. Ultracold molecules in the
micro- and nano-Kelvin regimes promise to bring powerful new capabilities to
quantum emulation and quantum computing, thanks to their rich internal degrees
of freedom compared to atoms. They also open new possibilities for precision
measurement and the study of quantum chemistry. Quantum gases of atoms were
made possible by collision-based cooling schemes, such as evaporative cooling.
For ultracold molecules, thermalization and collisional cooling have not been
realized. With other techniques such as supersonic jets and cryogenic buffer
gases, studies have been limited to temperatures above 10 mK. Here we show
cooling of NaLi molecules at micro- and nano-Kelvin temperatures through
collisions with ultracold Na atoms, both prepared in their stretched hyperfine
spin states. We find a lower bound on the elastic to inelastic collision ratio
between molecules and atoms greater than 50 -- large enough to support
sustained collisional cooling. By employing two stages of evaporation, we
increase the phase-space density (PSD) of the molecules by a factor of 20,
achieving temperatures as low as 220 nK. The favorable collisional properties
of a Na and NaLi mixture show great promise for making deeply quantum
degenerate dipolar molecules and suggest the potential for such cooling in
other systems
Dark-ages reionization and galaxy formation simulation XI: Clustering and halo masses of high redshift galaxies
We investigate the clustering properties of Lyman-break galaxies (LBGs) at
- . Using the semi-analytical model {\scshape Meraxes} constructed
as part of the Dark-ages Reionization And Galaxy-formation Observables from
Numerical Simulation (DRAGONS) project, we predict the angular correlation
function (ACF) of LBGs at - . Overall, we find that the predicted
ACFs are in good agreement with recent measurements at and from observations consisting of the Hubble eXtreme Deep Field (XDF), the
Hubble Ultra-Deep Field (HUDF) and Cosmic Assembly Near-infrared Deep
Extragalactic Legacy Survey (CANDELS) field. We confirm the dependence of
clustering on luminosity, with more massive dark matter haloes hosting brighter
galaxies, remains valid at high redshift. The predicted galaxy bias at fixed
luminosity is found to increase with redshift, in agreement with observations.
We find that LBGs of magnitude at reside in dark matter haloes of mean mass -
, and this dark matter halo mass does not evolve
significantly during reionisation.Comment: 14 pages, 10 figures, published in MNRA
Magnetic trapping of ultracold molecules at high density
Trapping ultracold molecules in conservative traps is essential for
applications -- such as quantum state-controlled chemistry, quantum
simulations, and quantum information processing. These applications require
high densities or phase-space densities. We report magnetic trapping of NaLi
molecules in the triplet ground state at high density () and ultralow temperature (). Magnetic
trapping at these densities allows studies on both atom-molecule and
molecule-molecule collisions in the ultracold regime in the absence of trapping
light, which has often lead to undesired photo-chemistry. We measure the
inelastic loss rates in a single spin sample and spin-mixtures of fermionic
NaLi as well as spin-stretched NaLiNa mixtures. We demonstrate sympathetic
cooling of NaLi molecules in the magnetic trap by radio frequency evaporation
of co-trapped Na atoms and observe an increase in the molecules' phase-space
density by a factor of .Comment: 8 pages, 4 figure
The global integrated world ocean assessment: linking observations to science and policy across multiple scales
In 2004, the United Nations (UN) General Assembly approved a Regular Process to report on the environmental, economic and social aspects of the world's ocean. The Regular Process for Global Reporting and Assessment of the State of the Marine Environment, including Socioeconomic Aspects produced the first global integrated assessment of the marine environment in December 2016 (known as the first World Ocean Assessment). The second assessment, to be delivered in December 2020, will build on the baselines included in the first assessment, with a focus on establishing trends in the marine environment with relevance to global reporting needs such as those associated with the UN Sustainable Development Goals. Central to the assessment process and its outputs are two components. First, is the utilization of ocean observation and monitoring outputs and research to temporally assess physical, chemical, biological, social, economic and cultural components of coastal and marine environments to establish their current state, impacts currently affecting coastal and marine environments, responses to those impacts and associated ongoing trends. Second, is the knowledge brokering of ocean observations and associated research to provide key information that can be utilized and applied to address management and policy needs at local, regional and global scales. Through identifying both knowledge gaps and capacity needs, the assessment process also provides direction to policy makers for the future development and deployment of sustained observation systems that are required for enhancing knowledge and supporting national aspirations associated with the sustainable development of coastal and marine ecosystems. Input from the ocean observation community, managers and policy makers is critical for ensuring that the vital information required for supporting the science policy interface objectives of the Regular Process is included in the assessment. This community white paper discusses developments in linking ocean observations and science with policy achieved as part of the assessment process, and those required for providing strategic linkages into the future.Agência financiadora - United Nations Division for Ocean Affairs and the Law of the Seainfo:eu-repo/semantics/publishedVersio
- …