Gravitational Collapse, Chaos in CFT Correlators and the Information Paradox

We consider gravitational collapse of a massless scalar field in asymptotically Anti de Sitter spacetime. Following the AdS/CFT dictionary we further study correlations in the field theory side by way of the Klein-Gordon equation of a probe scalar field in the collapsing background. We present evidence that in a certain regime the probe scalar field behaves chaotically, thus supporting Hawking's argument in the black hole information paradox proposing that although the information can be retrieved in principle, deterministic chaos impairs, in practice, the process of unitary extraction of information from a black hole. We emphasize that quantum chaos will change this picture.Comment: 5 pages, 3 figure

Experimental study of z resolution in acousto-optical coherence tomography using random phase jumps on ultrasound and light

Acousto-Optical Coherence Tomography (AOCT) is a variant of Acousto Optic Imaging (also called Ultrasound modulated Optical Tomography) that makes possible to get resolution along the ultrasound propagation axis $z$. We present here new AOCT experimental results, and we study how the $z$ resolution depends on time step between phase jumps $T_\phi$, or on the correlation length $\Delta z$. By working at low resolution, we perform a quantitative comparison of the $z$ measurements with the theoretical Point Spread Function (PSF). We present also images recorded with different $z$ resolution, and we qualitatively show how the image quality varies with $T_\phi$, or $\Delta z$

A Model for Multi-property Galaxy Cluster Statistics

The massive dark matter halos that host groups and clusters of galaxies have observable properties that appear to be log-normally distributed about power-law mean scaling relations in halo mass. Coupling this assumption with either quadratic or cubic approximations to the mass function in log space, we derive closed-form expressions for the space density of halos as a function of multiple observables as well as forms for the low-order moments of properties of observable-selected samples. Using a Tinker mass function in a {\Lambda}CDM cosmology, we show that the cubic analytic model reproduces results obtained from direct, numerical convolution at the 10 percent level or better over nearly the full range of observables covered by current observations and for redshifts extending to z = 1.5. The model provides an efficient framework for estimating effects arising from selection and covariance among observable properties in survey samples.Comment: 9 pages, 4 figures, uses on-line mass function calculator http://hmf.icrar.org/. Submitted to MNRA

Multi-Wavelength Facets of Galaxy Clusters

Cluster cosmology, as investigated by the number counts method, is deeply linked to the constituent properties of our Universe and small-scale astrophysical phenomena. In the number counts method, a key challenge is relating observations of cluster galaxy members or the gas component to the total mass of the system. This dissertation aims to address this challenge by developing a better understanding of mass--observables relation, with a subsequent goal of enhancing the interpretation of cluster samples that have emerged from large-scale multi-wavelength surveys. These surveys include the XMM-XXL project, the Local Cluster Substructure Survey (LoCuSS), and eventually the Dark Energy Survey data (DES). The results of this work support the science goal of understanding the content and evolution of the Universe's most massive systems, thereby improving cosmological constraints leading to a better understanding of the constituents of our Universe. In this dissertation, I propose a novel method for cluster mass estimation based on member galaxy kinematics. I demonstrate a percent-level accuracy for the expected conditional log-mass, which implies that this algorithm is one of the most accurate algorithms available in the literature. The accuracy of this algorithm is extensively evaluated on a set of large-scale simulations. Next, all key systematics are identified and calibrated. With this method, we then estimate dynamical masses of a large, optically-selected cluster sample derived from the Sloan Digital Sky Survey (SDSS) and an X-ray-selected cluster sample derived from the XXL Survey. The multi-wavelength scaling behavior of cluster observables is driven by the astrophysical evolution of the baryonic components within the potential well of massive halos. To facilitate the multi-wavelength scaling modeling, I study the stellar and gas content of dark matter halos extracted from the BAHAMAS simulations, a set of large-scale, full-physics hydrodynamical simulations. The results verify the popular log-normal model of the halo population, but deviate from the power-law approximation. With these simulations, I establish a new set of predictions, most importantly an intrinsic anti-correlation between gas mass and stellar content of these systems. This anti-correlation is a key prediction that we continue to strive to confirm through a subset of the LoCuSS cluster sample. I implement a robust hierarchical Bayesian inference algorithm, which models the effects of sample selection and the measurement error covariance, to examine the gas and stellar contents of the underlying dark matter halos. To study the relation between the mass of dark matter halos and the multi-wavelength cluster observables, I apply this model to a subset of the LoCuSS cluster sample. Most importantly, this model enables us to examine the predicted anti-correlation between gas and stellar content of these systems. Finally, the results of this study establish the first empirical evidence for this anti-correlation, which has a profound implication for how the Universe's most massive structures formed and evolved.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145977/1/aryaf_1.pd

Increasing the imaging capabilities of multimode fibers by exploiting the properties of highly scattering media

We present a novel design that exploits the focusing properties of scattering media to increase the resolution and the working distance of multimode fiber based imaging devices. Placing a highly scattering medium in front of the distal tip of the multimode fiber enables the formation of smaller sized foci at increased working distances away from the fiber tip. We perform a parametric study of the effect of the working distance and the separation between the fiber and the scattering medium on the focus size. We experimentally demonstrate submicron focused spots as far away as 800{\mu}m with 532nm light.Comment: 4 pages, 3 figure

ActiveRemediation: The Search for Lead Pipes in Flint, Michigan

We detail our ongoing work in Flint, Michigan to detect pipes made of lead and other hazardous metals. After elevated levels of lead were detected in residents' drinking water, followed by an increase in blood lead levels in area children, the state and federal governments directed over $125 million to replace water service lines, the pipes connecting each home to the water system. In the absence of accurate records, and with the high cost of determining buried pipe materials, we put forth a number of predictive and procedural tools to aid in the search and removal of lead infrastructure. Alongside these statistical and machine learning approaches, we describe our interactions with government officials in recommending homes for both inspection and replacement, with a focus on the statistical model that adapts to incoming information. Finally, in light of discussions about increased spending on infrastructure development by the federal government, we explore how our approach generalizes beyond Flint to other municipalities nationwide.Comment: 10 pages, 10 figures, To appear in KDD 2018, For associated promotional video, see https://www.youtube.com/watch?v=YbIn_axYu9

Acousto-optical coherence tomography with a digital holographic detection scheme

Acousto-optical coherence tomography (AOCT) consists in using random phase jumps on ultrasound and light to achieve a millimeter resolution when imaging thick scattering media. We combined this technique with heterodyne off-axis digital holography. Two-dimensional images of absorbing objects embedded in scattering phantoms are obtained with a good signal-to-noise ratio. We study the impact of the phase modulation characteristics on the amplitude of the acousto-optic signal and on the contrast and apparent size of the absorbing inclusion

Effectiveness of Acceptance and Commitment Therapy on the Life Expectancy, Resilience and Death Anxiety in Women with Cancer

Introduction: An annual record of 90,000 new cases of cancer in Iran and a mortality rate of 55,000 affected cases is indicative of alarming outbreak of cancer in the country to the extent that an average of 100 people die each day due to this disease. The purpose of the present research is to evaluate the effectiveness of acceptance and commitment therapy (ACT) on the life expectancy, resilience and death anxiety in women with cancer.Methods: The present research is a semi-experimental research with pretest-posttest control group design. The research population consisted of all women with cancer who referred to the Cancer Institute of Imam Khomeini Hospital in Tehran in 2017. Thirty women who met the inclusion criteria were randomly divided into two groups: experimental and control. Life expectancy, resilience and death anxiety scales were used and multivariate covariance analysis was applied for data analysis.Results: The results showed that life expectancy increased in the experimental group in compare with the control group (p<0.05) and the death anxiety of the experimental group decreased in compare to the control group (p<0.05) after acceptance and commitment training.Conclusion: Acceptance and commitment therapy is effective in increasing the life expectancy and resilience and also in decreasing death Anxiety in women patient with cancer. These findings can be used in designing of psychological treatment interventions in the field of cancer.Declaration of Interest: Non