There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

From the Publisher: 
The accessible presentation of this book gives both a general view of the entire computer vision enterprise and also offers sufficient detail to be able to build useful applications. Users learn techniques that have proven to be useful by first-hand experience and a wide range of mathematical methods. A CD-ROM with every copy of the text contains source code for programming practice, color images, and illustrative movies. Comprehensive and up-to-date, this book includes essential topics that either reflect practical significance or are of theoretical importance. Topics are discussed in substantial and increasing depth. Application surveys describe numerous important application areas such as image based rendering and digital libraries. Many important algorithms broken down and illustrated in pseudo code. Appropriate for use by engineers as a comprehensive reference to the computer vision enterprise.

Computer vision : a modern approach = 计算机视觉 : 一种现代的方法

Researchers demonstrate the ability to multiplex and transfer data between twisted beams of light with different amounts of orbital angular momentum — a development that provides new opportunities for increasing the data capacity of free-space optical communications links.

/pdf/terabit-free-space-data-transmission-employing-orbital-47zsgn5cdx.pdf

Terabit free-space data transmission employing orbital angular momentum multiplexing

/pdf/stochastic-processes-detection-and-estimation-6-432-course-1r8ndg6brp.pdf

STOCHASTIC PROCESSES, DETECTION AND ESTIMATION 6.432 Course Notes

https://dspace.mit.edu/openaccess-disseminate/1721.1/106213

Finite-key analysis for time-energy high-dimensional quantum key distribution

Recent studies have shown that the use of predetection processing can greatly improve the quality of images formed through atmospheric turbulence. It is generally assumed that the object to be imaged lies within a single isoplanatic patch, and it is recognized that the angular subtense of the isoplanatic patch may be quite small, comparable to the seeing limit. In this paper the use of predetection processing for objects which comprise many isoplanatic elements is considered. It is shown that an atmosphere–lens system behaves macroscopically as though it consisted microscopically of a collection of uncorrelated scatterers with random scattering strengths which contribute image components with varying spatial and spatial-frequency displacements. In communication theory such systems are referred to as wide-sense stationary uncorrelated scatter (WSSUS) channels and are characterized by a macroscopic scattering function. The macroscopic scattering function for the atmosphere is derived and used to show that under typical turbulence-strength conditions the seeing limit can resolve the isoplanatic patch. Thus the fields from different isoplanatic patches of an extended object may be separated in the image plane of an objective lens and processed individually to obtain a diffraction-limited image.

Diffraction-limited atmospheric imaging of extended objects*

The long-standing problem of determining the classical communication capacities of Gaussian bosonic channels is addressed by determining upper and lower bounds for the classical capacities of important active and passive bosonic channels. The results apply to any bosonic thermal-noise channel, including electromagnetic signaling at any frequency.

Electromagnetic channel capacity for practical purposes

Two-way Gaussian protocols have the potential to increase quantum key distribution (QKD) protocols' secret-key rates by orders of magnitudes [Phys. Rev. A 94, 012322 (2016)]. Security proofs for two-way protocols, however, are underdeveloped at present. In this paper, we establish a security proof framework for the general coherent attack on two-way Gaussian protocols in the asymptotic regime. We first prove that coherent-attack security can be reduced to collective-attack security for all two-way QKD protocols. Next, we identify two different constraints that each provide intrusion parameters which bound an eavesdropper's coherent-attack information gain for any two-way Gaussian QKD protocol. Finally, we apply our results to two such protocols.

Jeffrey H. Shapiro

Papers

STOCHASTIC PROCESSES, DETECTION AND ESTIMATION 6.432 Course Notes

Finite-key analysis for time-energy high-dimensional quantum key distribution

Diffraction-limited atmospheric imaging of extended objects*

Electromagnetic channel capacity for practical purposes

Security-proof framework for two-way Gaussian quantum-key-distribution protocols