Computation of Λˉ\bar{\Lambda} and λ1\lambda_1 with Lattice QCD

We pursue a new method, based on lattice QCD, for determining the quantities $\bar{\Lambda}$, $\lambda_1$, and $\lambda_2$ of heavy-quark effective theory. We combine Monte Carlo data for the meson mass spectrum with perturbative calculations of the short-distance behavior, to extract $\bar{\Lambda}$ and $\lambda_1$ from a formula from HQET. Taking into account uncertainties from fitting the mass dependence and from taking the continuum limit, we find $\bar{\Lambda} = 0.68{+0.02}_{-0.12} \text{GeV}$ and $\lambda_1 = -(0.45 \pm 0.12) \text{GeV}^2$ in the quenched approximation.Comment: 7 pp, 4 figs (in v2 Fig. 4 now shows Ref. 13, as advertised); in v3 error in BLM scale is correcte

Weak Lensing of Intensity Mapping: the Cosmic Infrared Background

Gravitational lensing deflects the paths of cosmic infrared background (CIB) photons, leaving a measurable imprint on CIB maps. The resulting statistical anisotropy can be used to reconstruct the matter distribution out to the redshifts of CIB sources. To this end, we generalize the CMB lensing quadratic estimator to any weakly non-Gaussian source field, by deriving the optimal lensing weights. We point out the additional noise and bias caused by the non-Gaussianity and the `self-lensing' of the source field. We propose methods to reduce, subtract or model these non-Gaussianities. We show that CIB lensing should be detectable with Planck data, and detectable at high significance for future CMB experiments like CCAT-Prime. The CIB thus constitutes a new source image for lensing studies, providing constraints on the amplitude of structure at intermediate redshifts between galaxies and the CMB. CIB lensing measurements will also give valuable information on the star formation history in the universe, constraining CIB halo models beyond the CIB power spectrum. By laying out a detailed treatment of lens reconstruction from a weakly non-Gaussian source field, this work constitutes a stepping stone towards lens reconstruction from continuum or line intensity mapping data, such as the Lyman-alpha emission, absorption, and the 21cm radiation.Comment: Accepted in Physical Review

International Partnerships, Foreign Control and Income Levels: Theory and Evidence

We analyze the effects of different regimes of control rights over critical resources on the total domestic income of open economies. We consider home control, foreign control, and international partnerships in a theoretical model where contracts are incomplete, resource exploitation requires local capital, and foreign technologies are more efficient. Enacting foreign control is never optimal, and assigning complete residual rights to foreign ?firms reduces domestic income. Two testable predictions are derived. First, international partnerships tend to generate higher domestic income than foreign control. Second, the typical regime choice is either partnership or foreign control when the international relative pro?tability of the domestic resource endowment is high or intermediate, and home control with low relative pro?tability. We test these predictions using a new dataset on petroleum ownership structures for up to 68 countries between 1867-2008, ?finding strong empirical support for the theoretical results.Property rights, control rights, income, oil, panel data

Accurate Predictions of Hovering Rotor Flows Using CFD

With work on the S-76 rotor providing encouraging results regarding the prediction of integral loads with CFD in hover, the XV-15 rotor is now analysed. Fully turbulent and transitional results are obtained showing the capability of modern CFD methods. The transition onset and distribution of skin friction are well predicted and were found to have a mild effect on the overall figure of merit. This work also shows the potential of transport-based models for transition prediction in complex 3D flows. Finally, hover simulations for the PSP blade are also shown in terms of surface pressure coefficient and wake visualisation

An Application of Volterra Series to IC Buffer Models

International audienceThis paper presents a Volterra-based method of behavioral modeling for the I/O buffers of digital ICs. While this technique brings a slight improvement in accuracy over previous ones, its main strength is a greater degree of generality. With a modeling approach less dependent on the nature of the devices and more easily extendable to include the effects of multiple inputs one may hope better meet the challenges of advancing technology. The proposed models can be obtained from device port transient responses only and can be easily implemented in any simulation environment, including SPICE-based circuit description software. Two illustrative examples conclude the paper

Bi-metric theory of gravity from the non-chiral Plebanski action

We study a modification of the Plebanski action for general relativity, which leads to a modified theory of gravity with eight degrees of freedom. We show how the action can be recasted as a bi-metric theory of gravity, and expanding around a bi-flat background we identify the six extra degrees of freedom with a second, massive graviton and a scalar mode.Comment: 28 pages. v2 minor typos correcte

Technical and logistical support for course assessment

Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (leaf 31).Course assessment is a valuable tool for improving teaching and learning in a class. As part of the course assessment project being started for 6.042 and several other EECS classes, students took diagnostic entry exams and end-of-term surveys in which they were asked to rate themselves on various objectives of the class. I examined this data along with the students' grades, and performed calculations such as finding correlation coefficients to determine what areas of the course might need improvement. After analyzing four semesters of 6.042, it was discovered that the correlation coefficients were not as high as expected. However, the results are still useful in assessing the course, and with several improvements to the current assessment procedure, future results may be more clear.by Simone N. Pugh.M.Eng.and S.B

The puzzle of non-participation in continuing training : an empirical study of chronic vs. temporary non-participation

"Although participation in continuing vocational training is often found to be associated with considerable individual benefits, a puzzlingly large number of people still do not take part in training. In order to solve the puzzle we distinguish between temporary and chronic non-participants. Previous studies have shown that training participants and non-participants differ in unobservable characteristics and therefore self-select into training or not. We show that even non-participants cannot be treated as a homogeneous group: there are those who never take part in training (chronic non-participants) and those who are not currently taking part (temporary (non-)participants). Using a unique data set of non-participants commissioned by the German 'Expert Commission on Financing Lifelong Learning' and covering a very large number of individuals not taking part in training, we separate and compare chronic and temporary non-participants. By estimating a sample selection model using maximum likelihood estimation we take potential selection effects into account: temporary (non-)participants may be more motivated or may have different inherent skills than chronic nonparticipants. We find that chronic non-participants would have higher costs than temporary (non-)participants and their short-term benefits associated with their current jobs would be lower. However, in the long run even chronic non-participants would benefit similarly from participation due to improved prospects on the labor market. The results indicate that chronic non-participants either misperceive future developments or suffer from an exceptionally high discount rate, which in turn leads in their view to a negative cost-benefit ratio for training." (Author's abstract, IAB-Doku) ((en)) Additional Information Kurzfassung (deutsch) Executive summary (English)Weiterbildung, Teilnehmer, Bildungsbeteiligung, Bildungsinvestitionen, Bildungsertrag, Kosten-Nutzen-Analyse, Bildungsökonomie