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NDLTD Union Catalog (1.532.874 recursos)
The NDLTD Union Catalog is an OAICat server containing thesis and dissertation records harvested from registered NDLTD OAI repositories
M.I.T. Theses and Dissertation
The NDLTD Union Catalog is an OAICat server containing thesis and dissertation records harvested from registered NDLTD OAI repositories
M.I.T. Theses and Dissertation
Murto, Pauli; Liski, Matti
Energy costs are notoriously uncertain but what is the effect of this on energysaving investments? We find that real-option frictions imply a novel equilibrium response to increasing but uncertain energy costs: early investments are cautious but ultimately real-option frictions endogenously vanish, and the activity affected by higher energy costs fully recovers. We use electricity market data for counterfactual analysis of the real-option mark-ups and policy experiments. Uncertainty alone implies that the early compensation to new technologies exceeds entry costs by multiple factors, and that uncertainty-reducing subsidies to green energy can benefit the consumer side at the expense of the old...
Babusiaux, Denis; Pierru, Axel
According to the standard analysis of commodity prices, stockpiling is a necessary signature of speculation. This paper develops an approach suggesting that speculation may temporarily push crude oil prices above the level justified by physical-market fundamentals, without necessarily resulting in a significant increase in oil inventories. Looking beyond debate on the value of oil-demand price-elasticity, showing a demand curve makes sense only if we consider a fixed time horizon (e.g. short-run). The scenario of oil demand slowly but continuously adjusting to a price fuelled by speculation implies that price elasticity of demand is an increasing function of the time horizon...
Wozny, Nathan; Allcott, Hunt
It is often asserted that consumers purchasing automobiles or other goods and services underweight the costs of gasoline or other "add-ons." We test this hypothesis in the US automobile market by examining the effects of time series variation in gasoline price expectations on the prices and market shares of vehicles with different fuel economy ratings. When gas prices rise, demand for high fuel economy vehicles increases, pushing up their relative prices. Market share changes - increased production of high fuel economy vehicles and scrappage of low fuel economy vehicles - attenuate these price changes. Intuitively, the less that equilibrium vehicle...
Chen, Y.-H. Henry; Paltsev, Sergey; Reilly, John; Chan, Gabriel
Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).
Reilly, John; Paltsev, Sergey; Winchester, Niven
Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).
Jones, Christopher
Reducing the European Union GHG emissions by at least 80% by 2050 will require a near zero carbon electricity, road and rail transport industry, and heating and cooling in buildings. As compared to “business as usual” the amount of energy required will basically vary according to the level of energy efficiency: it is the “system scale”. Then it is the “system design” which will provide the needed carbon-free technologies consisting of renewable, nuclear and fossil fuels with carbon capture and storage.
A zero carbon energy system by 2050 is then demonstrated to be feasible. However it is far from easy...
Metcalf, Gilbert E.
Federal tax policy provides a broad array of incentives for energy investment. I review those policies and construct estimates of marginal effective tax rates for different energy capital investments as of 2007. Effective tax rates vary widely across investment classes. I then consider investment in wind generation capital and regress investment against a user cost of capital measure along with other controls. I find that wind investment is strongly responsive to changes in tax policy. Based on the coefficient estimates the elasticity of investment with respect to the user cost of capital is in the range of -1 to -2....
Tong, Lang; Anandkumar, Animashree; Willsky, Alan S.
The problem of binary hypothesis testing is considered when the measurements are drawn from a Markov random field (MRF) under each hypothesis. Spatial dependence of the measurements is incorporated by explicitly modeling the influence of sensor node locations on the clique potential functions of each MRF hypothesis. The nodes are placed i.i.d. in expanding areas with increasing sample size. Asymptotic performance of hypothesis testing is analyzed through the Neyman-Pearson type-II error exponent. The error exponent is expressed as the limit of a functional over dependency edges of the MRF hypotheses for acyclic graphs. Using the law of large numbers for...
Suárez, Alberto; Altman, Eitan; Menache, Ishai
We consider decentralized medium-access control in which many pairwise interactions occur between randomly selected users that belong to a large population. In each local interaction, the users involved compete over an access opportunity. A given user has a fixed number of access attempts and a fixed budget for buying different priority levels. In each time-slot, the access is attributed to the user with the largest priority level. We analyze this problem under both cooperative as well as competitive frameworks. We show that unlike many standard team problems, optimal pure policies do not exist in the team framework, but both an...
Bühler, Oliver; Muller, Caroline
As part of an ongoing effort to develop a parameterization of wave-induced abyssal mixing, the authors derive an heuristic model for nonlinear wave breaking and energy dissipation associated with internal tides. Then the saturation and dissipation of internal tides for idealized and observed topography samples are investigated. One of the main results is that the wave-induced mixing could be more intense and more confined to the bottom than previously assumed in numerical models. Furthermore, in this model wave breaking and mixing clearly depend on the small scales of the topography below 10 km or so, which is below the current...
Belloni, Alexandre; Freund, Robert Michael
In this paper we study the homogeneous conic system F : Ax = 0, x ∈ C \ {0}. We choose a point ¯s ∈ intC∗ that serves as a normalizer and consider computational properties of the normalized system F¯s : Ax = 0, ¯sT x = 1, x ∈ C. We show that the computational complexity of solving F via an interior-point method depends
only on the complexity value ϑ of the barrier for C and on the symmetry of the origin in the image set H¯s := {Ax :
¯sT x = 1, x ∈ C}, where the symmetry of...
Belloni, Alexandre; Freund, Robert Michael
For a conic linear system of the form Ax ∈ K, K a convex cone, several
condition measures have been extensively studied in the last dozen years.Among these,
Renegar’s condition number C(A) is arguably the most prominent for its relation to
data perturbation, error bounds, problem geometry, and computational complexity of
algorithms.Nonetheless, C(A) is a representation-dependent measurewhich is usually
difficult to interpret and may lead to overly conservative bounds of computational
complexity and/or geometric quantities associated with the set of feasible solutions.
Herein we showthat Renegar’s condition number is bounded from above and belowby
certain purely geometric quantities associated with A and K; furthermore our bounds
highlight the role...
Park, Matthew; Perrott, Michael H.
The use of a VCO-based integrator and quantizer within a continuous-time (CT) \Delta \Sigma analog-to-digital converter (ADC) structure is explored, and a custom prototype in a 0.13 \mum CMOS with a measured performance of 81.2/78.1 dB SNR/SNDR over a 20 MHz bandwidth while consuming 87 mW from a 1.5 V supply and occupying an active area of 0.45 mm[superscript 2] demonstrated. A key innovation is the explicit use of the oscillator's output phase to avoid the signal distortion that had severely limited the performance of earlier VCO-based ADCs, which had made use of its output frequency only. The proposed VCO-based...
Aldridge, J. Wayne; Tindell, Amy J.; Berridge, Kent C.; Zhang, Jun; Smith, Kyle S.
Incentive salience is a motivational property with ‘magnet-like’ qualities. When attributed to reward-predicting stimuli (cues), incentive salience triggers a pulse of ‘wanting’ and an individual is pulled toward the cues and reward. A key computational question is how incentive salience is generated during a cue re-encounter, which combines both learning and the state of limbic brain mechanisms. Learning processes, such as temporal-difference models, provide one way for stimuli to acquire cached predictive values of rewards. However, empirical data show that subsequent incentive values are also modulated on the fly by dynamic fluctuation in physiological states, altering cached values in ways...
Octavio, Leah M.; Gedeon, Kamil S.; Maheshri, Narendra
Epigenetic switches encode their state information either locally, often via covalent modification of DNA or histones, or
globally, usually in the level of a trans-regulatory factor. Here we examine how the regulation of cis-encoded epigenetic
switches controls the extent of heterogeneity in gene expression, which is ultimately tied to phenotypic diversity in a
population. We show that two copies of the FLO11 locus in Saccharomyces cerevisiae switch between a silenced and
competent promoter state in a random and independent fashion, implying that the molecular event leading to the
transition occurs locally at the promoter, in cis. We further quantify the effect of trans regulators both...
Coppi, Bruno
The theory of the composite plasma disk structures and of the relevant
magnetic field configurations that can surround black holes is presented,
consistently with recent experimental observations indicating that highly
coherent magnetic field configurations exist in the core of these structures. Concepts
developed to describe the physics of magnetically confined laboratory plasmas are
used. Thus the “paradox”, that arises when considering accreting plasmas in the
presence of a transverse magnetic field is resolved by considering accretion as an intermittent process whereby particles are carried in steps, along a sequence of
magnetic separatrices containing the formed magnetic islands, by the onset of the
equivalent of “edge localized modes” (ELMs)...
Le Gall, Francois; Tani, Seiichiro; Russell, Alexander; Aaronson, Scott
This paper studies the one-way communication complexity of the subgroup membership problem, a classical problem closely related to basic questions in quantum computing. Here Alice receives, as input,
a subgroup H of a finite group G; Bob receives an element x ∈ G. Alice is permitted to send a single
message to Bob, after which he must decide if his input x is an element of H. We prove the following upper bounds on the classical communication complexity of this problem in the bounded-error setting: 1. The problem can be solved with O(log|G|) communication, provided the subgroup H is normal.
2. The problem...
Nguyen, Vy T.; Monroe, Jocelyn; Karagiorgi, Georgia Stelios; Conrad, Janet
The MiniBooNE Collaboration observes unexplained electronlike events in the reconstructed neutrino energy range from 200 to 475 MeV. With 6.46×10[superscript 20] protons on target, 544 electronlike events are observed in this energy range, compared to an expectation of 415.2±43.4 events, corresponding to an excess of 128.8±20.4±38.3 events. The shape of the excess in several kinematic variables is consistent with being due to either ν[subscript e] and ν[over-bar][subscript e] charged-current scattering or ν[subscript mu] neutral-current scattering with a photon in the final state. No significant excess of events is observed in the reconstructed neutrino energy range from 475 to 1250 MeV,...
McCarthy, Kevin Ahmad; Hertel, Scott Alexander; Figueroa-Feliciano, Enectali
We report results from the Cryogenic Dark Matter Search at the Soudan Underground Laboratory (CDMS II) featuring the full complement of 30 detectors. A blind analysis of data taken between October 2006 and July 2007 sets an upper limit on the weakly interacting massive particle (WIMP) nucleon spin-independent cross section of 6.6×10[superscript -44] cm[superscript 2] (4.6×10[superscript -44] cm[superscript 2] when combined with previous CDMS II data) at the 90% confidence level for a WIMP mass of 60 GeV/c[superscript 2]. This achieves the best sensitivity for dark matter WIMPs with masses above 44 GeV/c[superscript 2], and significantly restricts the parameter space for some...
Chou, F. C.; Liu, L.-K.; Chen, C. H.; Sheu, H. S.; Shu, G. J.; Chu, M.-W.; Huang, F.-T.; Lee, Patrick A.
We have recently demonstrated that x=0.71 and 0.84 are the two most stable single-phase compounds above x=0.5 in gamma-Na[subscript x]CoO[subscript 2] [G. J. Shu et al., Phys. Rev. B 76, 184115 (2007); F. C. Chou et al., Phys. Rev. Lett. 101, 127404 (2008)], and this structural investigation was performed on the single crystals and pulverized samples elaborately synthesized therein. Using the complementary techniques of x-ray and electron diffractions, we unambiguously established the existence of superlattices in x=0.71 and 0.84, sqrt12a[subscript p]×sqrt12a[subscript p]×3c[subscript p], and sqrt13a[subscript p]×sqrt13a[subscript p]×3c[subscript p] (a[subscript p] and c[subscript p] the hexagonal primitive cell parameters), respectively. The...