Targeted Undersmoothing

This paper proposes a post-model selection inference procedure, called targeted undersmoothing, designed to construct uniformly valid confidence sets for a broad class of functionals of sparse high-dimensional statistical models. These include dense functionals, which may potentially depend on all elements of an unknown high-dimensional parameter. The proposed confidence sets are based on an initially selected model and two additionally selected models, an upper model and a lower model, which enlarge the initially selected model. We illustrate application of the procedure in two empirical examples. The first example considers estimation of heterogeneous treatment effects using data from the Job Training Partnership Act of 1982, and the second example looks at estimating profitability from a mailing strategy based on estimated heterogeneous treatment effects in a direct mail marketing campaign. We also provide evidence on the finite sample performance of the proposed targeted undersmoothing procedure through a series of simulation experiments

Constraints on the radio loud/radio quiet dichotomy from the fundamental plane

The fundamental plane for black hole activity constitutes a tight correlation between jet power, X-ray luminosity, and black hole mass. Under the assumption that a Blandford-Znajek-type mechanism, which relies on black hole spin, contributes non-negligibly to jet production, the sufficiently small scatter in the fundamental plane shows that black hole spin differences of $\mid$$\Delta$a$\mid \sim$1 are not typical among the active galactic nuclei population. If $-$ as it seems $-$ radio loud and radio quiet objects are both faithful to the fundamental plane, models of black hole accretion in which the radio loud/radio quiet dichotomy is based on a spin dichotomy of a$\sim$1/a$\sim$0, respectively, are difficult to reconcile with the observations. We show how recent theoretical work based on differences in accretion flow orientation between retrograde and prograde, accommodates a small scatter in the fundamental plane for objects that do have non-negligible differences in black hole spin values. We also show that the dichotomy in spin between the most radio loud and the most radio quiet involves $\mid$$\Delta$a$\mid \approx$0. And, finally, we show how the picture that produces compatibility with the fundamental plane, also allows one to interpret other otherwise puzzling observations of jets across the mass scale including 1) the recently observed inverse relation between radio and X-rays at higher Eddington ratios in both black hole X-ray binaries as well as active galactic nuclei and 2) the apparent contradiction between jet power and black hole spin observed in X-ray hard and transitory burst states in X-ray binaries.Comment: 8 pages, 1 figure, accepted in MNRA

The Einstein solid state spectrometer and monitor proportional counter survey of low mass x‐ray binaries

The HEAO‐2 Einstein solid state spectrometer (SSS; 0.5–4.5 keV) and monitor proportional counter (MPC; 1.2–20.0 keV) carried out an extensive survey of 50 low mass x‐ray binaries (LMXB). Simultaneous SSS plus MPC spectra, selected on the basis of their intensity, were fit with a set of simple and complex spectral models. For all the sources, including Eddington‐limited bulge sources, bursters, dippers, the soft spectrum black hole candidates, and a few transients in decline, the spectra could be fit acceptably with combinations of thermal bremsstrahlung and blackbody spectra or a Comptonized spectrum and a blackbody. The results rule out optically thick disk models for the bright (Z) sources and for the bursters power law models are unacceptable. The SSS can confirm only the strongest of previously reported low energy emission lines due to OVIII or Fe L transitions. The data does not support a unique physical interpretation. © 1994 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87678/2/193_1.pd

AudioPairBank: Towards A Large-Scale Tag-Pair-Based Audio Content Analysis

Recently, sound recognition has been used to identify sounds, such as car and river. However, sounds have nuances that may be better described by adjective-noun pairs such as slow car, and verb-noun pairs such as flying insects, which are under explored. Therefore, in this work we investigate the relation between audio content and both adjective-noun pairs and verb-noun pairs. Due to the lack of datasets with these kinds of annotations, we collected and processed the AudioPairBank corpus consisting of a combined total of 1,123 pairs and over 33,000 audio files. One contribution is the previously unavailable documentation of the challenges and implications of collecting audio recordings with these type of labels. A second contribution is to show the degree of correlation between the audio content and the labels through sound recognition experiments, which yielded results of 70% accuracy, hence also providing a performance benchmark. The results and study in this paper encourage further exploration of the nuances in audio and are meant to complement similar research performed on images and text in multimedia analysis.Comment: This paper is a revised version of "AudioSentibank: Large-scale Semantic Ontology of Acoustic Concepts for Audio Content Analysis

Entanglement witnessing and quantum cryptography with non-ideal ferromagnetic detectors

We investigate theoretically the use of non-ideal ferromagnetic contacts as a mean to detect quantum entanglement of electron spins in transport experiments. We use a designated entanglement witness and find a minimal spin polarization of $\eta > 1/\sqrt{3} \approx 58$ required to demonstrate spin entanglement. This is significantly less stringent than the ubiquitous tests of Bell's inequality with $\eta > 1/\sqrt[4]{2}\approx 84$. In addition, we discuss the impact of decoherence and noise on entanglement detection and apply the presented framework to a simple quantum cryptography protocol. Our results are directly applicable to a large variety of experiments.Comment: 10 pages, 4 figure

On complemented copies of the space c0c_0 in spaces Cp(X,E)C_p(X,E)

We study the question for which Tychonoff spaces $X$ and locally convex spaces $E$ the space $C_p(X,E)$ of continuous $E$-valued functions on $X$ contains a complemented copy of the space $(c_0)_p=\{x\in\mathbb{R}^\omega\colon x(n)\to0\}$, both endowed with the pointwise topology. We provide a positive answer for a vast class of spaces, extending classical theorems of Cembranos, Freniche, and Doma\'nski and Drewnowski, proved for the case of Banach and Fr\'echet spaces $C_k(X,E)$. For given infinite Tychonoff spaces $X$ and $Y$, using the results of Henriksen and Woods and analysing relations between the space $C_p(X,C_p(Y))$ and the space $SC_p(X\times Y)$ of separately continuous real-valued functions on the product $X\times Y$, we show that $C_p(X,C_p(Y))$ contains a complemented copy of $(c_0)_p$ if and only if any of the spaces $C_p(X)$ and $C_p(Y)$ contains such a subspace. This approach applies also to show that, contrary to the case of the compact-open topology, for every infinite compact spaces $X$ and $Y$ the space $C_p(X\times Y)$ cannot be mapped onto the space $C_p(X,C_p(Y))$ by a continuous linear operator.Comment: 19 pages, comments are welcome