4,608 research outputs found
Thermo-refractive and thermo-chemical noise in the beamsplitter of GEO600 gravitational-wave interferometer
Braginsky, Gorodetsky, and Vyatchanin have shown that thermo-refractive
fluctuations are an important source of noise in interferometric
gravitational-wave detectors. In particular, the thermo-refractive noise in the
GEO600 beamsplitter is expected to make a substantial contribution to the
interferometer's total noise budget. Here we present a new computation of the
GEO600 thermo-refractive noise which takes into account the beam's elliptical
profile and, more importantly, the fact that the laser beam induces a standing
electromagnetic wave in the beamsplitter. The use of updated parameters results
in the overall reduction of the calculated noise amplitude by a factor of about
5 in the low-frequency part of the GEO600 band, compared to the previous
estimates. We also find, by contrast with previous calculations, that
thermo-refractive fluctuations result in white noise between 600 Hz and 39 MHz,
at a level of Hz. Finally, we describe a new type
of thermal noise, which we call the thermo-chemical noise. This is caused by a
random motion of optically-active chemical impurities or structural defects in
the direction along a steep intensity gradient of the standing wave. We discuss
the potential relevance of the thermo-chemical noise for GEO600.Comment: 5 pages, submitted to Phys. Rev.
A New Game Equivalence and its Modal Logic
We revisit the crucial issue of natural game equivalences, and semantics of
game logics based on these. We present reasons for investigating finer concepts
of game equivalence than equality of standard powers, though staying short of
modal bisimulation. Concretely, we propose a more finegrained notion of
equality of "basic powers" which record what players can force plus what they
leave to others to do, a crucial feature of interaction. This notion is closer
to game-theoretic strategic form, as we explain in detail, while remaining
amenable to logical analysis. We determine the properties of basic powers via a
new representation theorem, find a matching "instantial neighborhood game
logic", and show how our analysis can be extended to a new game algebra and
dynamic game logic.Comment: In Proceedings TARK 2017, arXiv:1707.0825
Optimizing Voluntary Deforestation Policy in the Face of Adverse Selection and Costly Transfers
As part of international climate change policy, voluntary opt-in programs to reduce emissions in unregulated sectors or countries have spurred considerable discussion. Since any regulator will make errors in predicting baselines, adverse selection will reduce efficiency since participants will self-select into the program. In contrast, pure subsidies lead to full participation but require large financial transfers; this is a particular challenge across countries. A global social planner facing costless transfers would choose such a subsidy to maximize efficiency. However, any actual policy needs to be individually rational for both the buying (industrialized) and selling (developing) country. We present a simple model to analyze this trade-off between adverse selection and infra-marginal transfers. The model leads to the following findings. First, extending the scale of voluntary programs both improves efficiency and reduces transfers. Second, the set of individually rational and Pareto efficient policies typically features a combination of credit discounting and stringent assigned baselines which reduce efficiency. Third, if the industrialized countries can be persuaded to be more generous, the feasible policy set can come close to the globally efficient policy to avoid deforestation..Voluntary opt-in; adverse selection; deforestation; offsets; emissions trading; REDD
Optimizing Voluntary Deforestation Policy in the Face of Adverse Selection and Costly Transfers
As part of international climate change policy, voluntary opt-in programs to reduce emissions in unregulated sectors or countries have spurred considerable discussion. Since any regulator will make errors in predicting baselines, adverse selection will reduce efficiency since participants will self-select into the program. In contrast, pure subsidies lead to full participation but require large financial transfers; this is a particular challenge across countries. A global social planner facing costless transfers would choose such a subsidy to maximize efficiency. However, any actual policy needs to be individually rational for both the buying (industrialized) and selling (developing) country. We present a simple model to analyze this trade-off between adverse selection and infra-marginal transfers. The model leads to the following findings. First, extending the scale of voluntary programs both improves efficiency and reduces transfers. Second, the set of individually rational and Pareto efficient policies typically features a combination of credit discounting and stringent assigned baselines which reduce efficiency. Third, if the industrialized countries can be persuaded to be more generous, the feasible policy set can come close to the globally efficient policy to avoid deforestation.Voluntary opt-in, adverse selection, deforestation, offsets, emissions trading, REDD, Agricultural and Food Policy, Community/Rural/Urban Development, Environmental Economics and Policy, Land Economics/Use, Q54, Q56,
The story of Oh: the aesthetics and rhetoric of a common vowel sound
Studies in Musical Theatre is the only peer-reviewed journal dedicated to musical theatre. It was launched in 2007 and is now in its seventh volume. It has an extensive international readership and is edited by Dominic Symonds and George Burrows.
This article investigates the use of the ‘word’ ‘Oh’ in a variety of different performance idioms. Despite its lack of ‘meaning’, the sound is used in both conversation and poetic discourse, and I discuss how it operates communicatively and expressively through contextual resonances, aesthetic manipulation and rhetorical signification. The article first considers the aesthetically modernist work of Cathy Berberian in Bussotti’s La Passion Selon Sade; then it considers the rhetorically inflected use of ‘Oh’ to construct social resonance in popular song;finally, it discusses two important uses of the sound ‘Oh’ which bookend the Broadway musical Oklahoma!, serving to consolidate the allegorical and musico-dramatic narrative of the show
Evidence and plausibility in neighborhood structures
The intuitive notion of evidence has both semantic and syntactic features. In
this paper, we develop an {\em evidence logic} for epistemic agents faced with
possibly contradictory evidence from different sources. The logic is based on a
neighborhood semantics, where a neighborhood indicates that the agent has
reason to believe that the true state of the world lies in . Further notions
of relative plausibility between worlds and beliefs based on the latter
ordering are then defined in terms of this evidence structure, yielding our
intended models for evidence-based beliefs. In addition, we also consider a
second more general flavor, where belief and plausibility are modeled using
additional primitive relations, and we prove a representation theorem showing
that each such general model is a -morphic image of an intended one. This
semantics invites a number of natural special cases, depending on how uniform
we make the evidence sets, and how coherent their total structure. We give a
structural study of the resulting `uniform' and `flat' models. Our main result
are sound and complete axiomatizations for the logics of all four major model
classes with respect to the modal language of evidence, belief and safe belief.
We conclude with an outlook toward logics for the dynamics of changing
evidence, and the resulting language extensions and connections with logics of
plausibility change
Bigger is Better: Avoided Deforestation Offsets in the Face of Adverse Selection
Voluntary opt-in programs to reduce emissions in unregulated sectors or countries have spurred considerable discussion. Since any regulator will make errors in predicting baselines and participants will self-select into the program, adverse selection will reduce efficiency and possibly environmental integrity. In contrast, pure subsidies lead to full participation but require large financial transfers. We present a simple model to analyze this trade-off between adverse selection and infra-marginal transfers. We find that increasing the scale of voluntary programs both improves efficiency and reduces transfers. We show that discounting (paying less than full value for offsets) is inefficient and cannot be used to reduce the fraction of offsets that are spurious while setting stringent baselines generally can. Both approaches reduce the cost to the offsets buyer. The effects of two popular policy options are less favorable than many believe: Limiting the number of offsets that can be one-for-one exchanged with permits in a cap-and-trade system will lower the offset price but also quality. Trading ratios between offsets and allowances have ambiguous environmental effects if the cap is not properly adjusted. This paper frames the issues in terms of avoiding deforestation but the results are applicable to any voluntary offset program.Environmental Economics and Policy, deforestation, offsets, adverse selection, REDD, climate change policy, opt-in.,
Unintended Consequences from Nested State & Federal Regulations: The Case of the Pavley Greenhouse-Gas-per-Mile Limits
Fourteen U.S. states recently pledged to adopt limits on greenhouse gases (GHGs) per mile of light-duty automobiles. Previous analyses predicted that these limits will yield significant reductions in GHGs. However, these studies did not consider critical factors that imply different results. This paper develops a multi-period numerical simulation model that accounts for these factors in assessing the impact of the proposed GHG-per-mile standards on U.S. gasoline consumption and GHG emissions. We find that while the state-level initiative would reduce significantly the emissions associated with new cars in the adopting states, it would give rise to very significant offsetting increases (“leakage”) elsewhere, in both new and used car markets. Because of interactions with the federal CAFE standard, technology spillovers mitigate leakage only slightly. In the most plausible scenarios considered, the leakage is around 70 percent. Correspondingly, the cost per gallon saved under the GHG-per-mile limits is about 72 percent higher than for an equivalent increase in the federal CAFE standard.greenhouse gases, environmental regulations, renewable energy, cars
Comparing theories: the dynamics of changing vocabulary. A case-study in relativity theory
There are several first-order logic (FOL) axiomatizations of special
relativity theory in the literature, all looking essentially different but
claiming to axiomatize the same physical theory. In this paper, we elaborate a
comparison, in the framework of mathematical logic, between these FOL theories
for special relativity. For this comparison, we use a version of mathematical
definability theory in which new entities can also be defined besides new
relations over already available entities. In particular, we build an
interpretation of the reference-frame oriented theory SpecRel into the
observationally oriented Signalling theory of James Ax. This interpretation
provides SpecRel with an operational/experimental semantics. Then we make
precise, "quantitative" comparisons between these two theories via using the
notion of definitional equivalence. This is an application of logic to the
philosophy of science and physics in the spirit of Johan van Benthem's work.Comment: 27 pages, 8 figures. To appear in Springer Book series Trends in
Logi
- …