197 research outputs found
Dualities among 1T-Field Theories with Spin, Emerging from a Unifying 2T-Field Theory
The relation between two time physics (2T-physics) and the ordinary one time
formulation of physics (1T-physics) is similar to the relation between a
3-dimensional object moving in a room and its multiple shadows moving on walls
when projected from different perspectives. The multiple shadows as seen by
observers stuck on the wall are analogous to the effects of the 2T-universe as
experienced in ordinary 1T spacetime. In this paper we develop some of the
quantitative aspects of this 2T to 1T relationship in the context of field
theory. We discuss 2T field theory in d+2 dimensions and its shadows in the
form of 1T field theories when the theory contains Klein-Gordon, Dirac and
Yang-Mills fields, such as the Standard Model of particles and forces. We show
that the shadow 1T field theories must have hidden relations among themselves.
These relations take the form of dualities and hidden spacetime symmetries. A
subset of the shadows are 1T field theories in different gravitational
backgrounds (different space-times) such as the flat Minkowski spacetime, the
Robertson-Walker expanding universe, AdS(d-k) x S(k) and others, including
singular ones. We explicitly construct the duality transformations among this
conformally flat subset, and build the generators of their hidden SO(d,2)
symmetry. The existence of such hidden relations among 1T field theories, which
can be tested by both theory and experiment in 1T-physics, is part of the
evidence for the underlying d+2 dimensional spacetime and the unifying
2T-physics structure.Comment: 33 pages, LaTe
Dual Field Theories In (d-1)+1 Emergent Spacetimes From A Unifying Field Theory In d+2 Spacetime
According to Two-Time Physics, there is more to space-time than can be
garnered with the ordinary formulation of physics. Two-Time Physics has shown
that the Standard Model of Particles and Forces is successfully reproduced by a
two-time field theory in 4 space and 2 time dimensions projected as a
holographic image on an emergent spacetime in 3+1 dimensions. Among the
successes of this approach is the resolution of the strong CP problem of QCD as
an outcome of the restrictions imposed by the higher symmetry structures in 4+2
dimensions. In this paper we launch a program to construct the duals of the
Standard Model as other holographic images of the same 4+2 dimensional theory
on a variety of emergent spacetimes in 3+1 dimensions. These dual field
theories are obtained as a family of gauge choices in the master 4+2 field
theory. In the present paper we deal with some of the simpler gauge choices
which lead to interacting Klein-Gordon field theories for the conformal scalar
with a predicted SO(d,2) symmetry in a variety of interesting curved spacetimes
in (d-1)+1 dimensions. More challenging and more interesting gauge choices
(including some that relate to mass) which are left to future work are also
outlined. Through this approach we discover a new realm of previously
unexplored dualities and hidden symmetries that exist both in the macroscopic
and microscopic worlds, at the classical and quantum levels. Such phenomena
predicted by 2T-physics can in principle be confirmed both by theory and
experiment. 1T-physics can be used to analyze the predictions but in most
instances gives no clue that the predicted phenomena exist in the first place.
This point of view suggests a new paradigm for the construction of a
fundamental theory that is likely to impact on the quest for unification.Comment: LaTeX, 35 page
International expansion, diversification and regulated firms' nonmarket strategy
Previous studies have shown that regulated firms tend to diversify for different reasons than unregulated ones. This is the case for product but also for geographical diversification, i.e. international expansion. The logic generally advanced is that regulated firms tend to diversify when they face costly and difficult relationships with the regulatory authority in charge of their sector. This approach, however, does not explain (1) what is really at the core of the problem in regulated firms’ relationships with regulators, (2) why these firms cannot overcome part of the problem by developing nonmarket strategies –lobbying, campaign contributions, etc.– to influence regulatory decisions, and (3) why they sometimes opt for international expansion rather than product diversification. In this paper, we propose a theoretical model that provides potential answers to these questions. We start by considering the firm-regulator relationship as an incomplete information problem, in which the firms know things that the regulator does not, but can cannot convey hard information about these things. In this setting, we show that when firms face tough nonmarket competition domestically, going abroad can create a mechanism that makes information transmission credible and therefore strengthen their position in their home market. International expansion, in consequence, can be a way to solve some of the problems that regulated firms face at home in addition to a way for these firms to grow their business abroad.International diversification, regulated firms, lobbying
Inter-organizational communities of practice: specificities and stakes
Inter-organizational communities of practice (IOCoPs) are today an emergent research topic and studies in this area are still in an exploratory phase. Theoretical mechanisms are vaguely specified and empirical studies are incipient. For this reason, this paper firstly aims at presenting the specificities and stakes of such organizational forms, establishing reference points for further research in this field. We will introduce the main features of IOCoPs and explain why they do not represent a mere subcategory of CoPs, but a unit of analysis per se. In this paper, we will follow a thematic approach to indicate IOCoPs’ specificities and stakes. We will thus look at the IOCoPs’ actors (in part I), IOCoPs as original organizational forms (part II), then IOCoPs’ life cycle (part III). Finally, we will synthesize IOCoPs’ distinctive features and conclude with a discussion on key interests of IOCoPs for both practitioners and academics.Community of practice; inter-organizational relationships; professional practice; expertise; knowledge management; learning; organizational boundaries; life-cycle
International Expansion, Diversification and Regulated Firm Nonmarket Strategy
Previous studies have shown that regulated firms diversify for reasons that are different than for unregulated firms. We explore some of these differences by providing a theoretical model that starts by considering the firm-regulator relationship as an incomplete information issue, in which a regulated incumbent has knowledge that the regulator does not have, but the firm cannot convey hard information about this knowledge. The incumbent faces both market and nonmarket competition from a new entrant. In that context, we show that when the firm faces tough nonmarket competition domestically, going abroad can create a mechanism that makes information transmission to the regulator more credible. International expansion can thus be a way to solve domestic nonmarket issues in addition to being a catalyst for growth
The political economy of international regulatory convergence in public utilities
To what extent should public utilities regulation be expected to converge across countries? When it occurs, will it generate good outcomes? Building on the core proposition of the New Institutional Economics that similar regulations generate different outcomes depending on their fit with the underlying domestic institutions, we develop a simple model and explore its implications by examining the diffusion of local loop unbundling (LLU) regulations. We argue that: one should expect some convergence in public utility regulation but with still a significant degree of local experimentation; this process will have very different impacts of regulation
Strong Purcell effect observed in single thick shell CdSe/CdS nanocrystals coupled to localized surface plasmons
High quality factor dielectric cavities designed to a nanoscale accuracy are
mostly used to increase the spontaneous emission rate of a single emitter. Here
we show that the coupling, at room temperature, between thick shell CdSe/CdS
nanocrystals and random metallic films offers a very promising alternative
approach. Optical modes confined at the nanoscale induce strong Purcell factors
reaching values as high as 60. Moreover the quantum emission properties can be
tailored: strong antibunching or radiative biexcitonic cascades can be obtained
with high photon collection efficiency and extremely reduced blinking.Comment: 16 pages, 7 figure
Spatially uniform enhancement of single quantum dot emission using plasmonic grating decoupler
International audience1 We demonstrate a spatially uniform enhancement of individual quantum dot (QD) fluorescence emission using plasmonic grating decouplers on thin gold or silver films. Individual QDs are deposited within the grating in a controlled way to investigate the position dependency on both the radiation pattern and emission enhancement. We also describe the optimization of the grating decoupler. We achieve a fluorescence enhancement ~3 times higher than using flat plasmon film, for any QD position in the grating. Future optical quantum devices require the development of photonic sources with control of light down to the single photon limit. Excellent examples of single photon emitters are the colloidal nanocrystal quantum dots (QDs) which are considered as the building blocks for future quantum devices such as quantum qubits and quantum cryptographic devices 1,2. The application area of quantum emitters is wide and these applications require control of their emission such as emission rate, polarization, spectral properties, collection efficiency etc. Integration of single molecule or nanocrystals into plasmonic structures has recently proved to be one of the most promising yet challenging ways to control the emission properties at the single photon level 3,
The inhibition of inflammatory molecule expression on 3T3-L1 adipocytes by berberine is not mediated by leptin signaling
In our previous study, we have shown that berberine has both anti-adipogenic and anti-inflammatory effects on 3T3-L1 adipocytes, and the anti-adipogenic effect is due to the down-regulation of adipogenic enzymes and transcription factors. Here we focused more on anti-inflammatory effect of berberine using real time RT-PCR and found it changes expressions of adipokines. We hypothesized that anti-adipogenicity of berberine mediates anti-inflammtory effect and explored leptin as a candidate mediator of this signaling. We studied this hypothesis by western blot analysis, but our results showed that berberine has no effect on the phosphorylations of STAT-3 and ERK which have important roles on leptin signaling. These results led us to conclude that the anti-inflammatory effect of berberine is not mediated by the inhibition of leptin signal transduction. Moreover, we have found that berberine down-regulates NF-κB signaling, one of the inflammation-related signaling pathway, through western blot analysis. Taken together, the anti-inflammatory effect of berberine is not mediated by leptin, and berberine induces anti-inflammatory effect independent of leptin signaling
Room temperature single-photon sources based on single colloidal nanocrystals in microcavities
Abstract Direct lithography of resist blends, embedding semiconductor colloidal nanocrystals (NCs) is an innovative way to achieve nanopositioning of NCs in quantum-confined optical resonators. In this work, we show a new appealing approach for the fabrication of single-photon sources operating at room temperature by localizing semiconductor colloidal NCs into vertical planar microcavities with lithographic techniques
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