Towards Zeptosecond-Scale Pulses from X-Ray Free-Electron Lasers

The short wavelength and high peak power of the present generation of free-electron lasers (FELs) opens the possibility of ultra-short pulses even surpassing the present (tens to hundreds of attoseconds) capabilities of other light sources - but only if x-ray FELs can be made to generate pulses consisting of just a few optical cycles. For hard x-ray operation (~0.1nm), this corresponds to durations of approximately a single attosecond, and below into the zeptosecond scale. This talk will describe a novel method to generate trains of few-cycle pulses, at GW peak powers, from existing x-ray FEL facilities by using a relatively short 'afterburner'. Such pulses would enhance research opportunity in atomic dynamics and push capability towards the investigation of electronic-nuclear and nuclear dynamics. The corresponding multi-colour spectral output, with a bandwidth envelope increased by up to two orders of magnitudes over SASE, also has potential applications.Comment: Submitted to 35th International Free Electron Laser Conference, New York, 201

The value of enhancing nutrient bioavailability of lentils: the Sri Lankan scenario

Lentil (Lens culinaris Medic.) is a pulse crop that belongs to the family Leguminosae. Lentils are rich in proteins, have 18 of the 20 amino acids including all 8 essential amino acids and provide a number of essential minerals and vitamins. Thus, lentils occupy an important place in the human diet, especially in developing countries, as a rich source of protein, vitamins and minerals. Although in many developing countries in Asia rice contributes significantly to human daily energy and nutritional requirements, its amino acid profile shows that rice lacks some essential amino acids. Therefore, given their rich composition of amino acids, lentils could act as an ideal supplement for rice-based diets. Although all red lentils are imported, they are the most widely consumed pulse among Sri Lankans. Red lentil consumption levels are significantly greater in the estate sector where the prevalence of under nutrition is high. Thus, this review was undertaken to understand the potential role of lentils in the Sri Lankan diet and how lentils can potentially be utilized to meet the nutritional needs of Sri Lankans. The study was based on an extensive literature review and information obtained through personal interviews with key participants in the red lentil industry of Sri Lanka. It was evident that red lentils are a rich source of nutrients, especially micro-nutrients, but their bioavailability is poor due to the presence of multiple anti-nutritive factors such as protease inhibitors, phenolic compounds and phytates. Although bioavailability of nutrients can be enhanced by changing food processing techniques, fortification and bio-fortification, lentil cooking patterns in Sri Lanka pose difficulties in adopting changed food processing techniques and fortification. Thus, bio-fortification would be the most viable option for enhancing nutrient availability in lentils. Since Sri Lanka does not produce lentils, such initiatives may have to be undertaken in exporting countries or in collaboration with international agricultural research centres. Any strategic investments in breeding new lentil varieties with high bioavailability would provide exporting countries a unique competitive edge in export markets. Such improvements would meet the nutritional needs, not only of Sri Lankans, but also of millions other Asian consumers who face similar nutritional challenges.Key words: Bioavailability, Consumption, Nutrition, lentils, Sri Lanka

The value of enhancing nutrient bioavailability of lentils: The Sri Lankan scenario

Lentil (Lens culinaris Medic.) is a pulse crop that belongs to the family Leguminosae. Lentils are rich in proteins, have 18 of the 20 amino acids including all 8 essential amino acids and provide a number of essential minerals and vitamins. Thus, lentils occupy an important place in the human diet, especially in developing countries, as a rich source of protein, vitamins and minerals. Although in many developing countries in Asia rice contributes significantly to human daily energy and nutritional requirements, its amino acid profile shows that rice lacks some essential amino acids. Therefore, given their rich composition of amino acids, lentils could act as an ideal supplement for rice-based diets. Although all red lentils are imported, they are the most widely consumed pulse among Sri Lankans. Red lentil consumption levels are significantly greater in the estate sector where the prevalence of under nutrition is high. Thus, this review was undertaken to understand the potential role of lentils in the Sri Lankan diet and how lentils can potentially be utilized to meet the nutritional needs of Sri Lankans. The study was based on an extensive literature review and information obtained through personal interviews with key participants in the red lentil industry of Sri Lanka. It was evident that red lentils are a rich source of nutrients, especially micro-nutrients, but their bioavailability is poor due to the presence of multiple anti-nutritive factors such as protease inhibitors, phenolic compounds and phytates. Although bioavailability of nutrients can be enhanced by changing food processing techniques, fortification and bio-fortification, lentil cooking patterns in Sri Lanka pose difficulties in adopting changed food processing techniques and fortification. Thus, bio-fortification would be the most viable option for enhancing nutrient availability in lentils. Since Sri Lanka does not produce lentils, such initiatives may have to be undertaken in exporting countries or in collaboration with international agricultural research centres. Any strategic investments in breeding new lentil varieties with high bioavailability would provide exporting countries a unique competitive edge in export markets. Such improvements would meet the nutritional needs, not only of Sri Lankans, but also of millions other Asian consumers who face similar nutritional challenges.Key words: Bioavailability, Consumption, Nutrition, lentils, Sri Lanka

The Electrosphere of Macroscopic "Quark Nuclei": A Source for Diffuse MeV Emissions from Dark Matter

Using a Thomas-Fermi model, we calculate the structure of the electrosphere of the quark antimatter nuggets postulated to comprise much of the dark matter. This provides a single self-consistent density profile from ultrarelativistic densities to the nonrelativistic Boltzmann regime that use to present microscopically justified calculations of several properties of the nuggets, including their net charge, and the ratio of MeV to 511 keV emissions from electron annihilation. We find that the calculated parameters agree with previous phenomenological estimates based on the observational supposition that the nuggets are a source of several unexplained diffuse emissions from the Galaxy. As no phenomenological parameters are required to describe these observations, the calculation provides another nontrivial verification of the dark-matter proposal. The structure of the electrosphere is quite general and will also be valid at the surface of strange-quark stars, should they exist.Comment: 20 Pages, REVTeX4.

PACE: Pattern Accurate Computationally Efficient Bootstrapping for Timely Discovery of Cyber-Security Concepts

Public disclosure of important security information, such as knowledge of vulnerabilities or exploits, often occurs in blogs, tweets, mailing lists, and other online sources months before proper classification into structured databases. In order to facilitate timely discovery of such knowledge, we propose a novel semi-supervised learning algorithm, PACE, for identifying and classifying relevant entities in text sources. The main contribution of this paper is an enhancement of the traditional bootstrapping method for entity extraction by employing a time-memory trade-off that simultaneously circumvents a costly corpus search while strengthening pattern nomination, which should increase accuracy. An implementation in the cyber-security domain is discussed as well as challenges to Natural Language Processing imposed by the security domain.Comment: 6 pages, 3 figures, ieeeTran conference. International Conference on Machine Learning and Applications 201

Start-to-end modelling of a mode-locked optical klystron free electron laser amplifier

A free electron laser (FEL) in a mode-locked optical klystron (MLOK) configuration is modelled using start-to-end simulations that simulate realistic electron beam acceleration and transport before input into a full three-dimensional FEL simulation code. These simulations demonstrate that the MLOK scheme is compatible with the present generation of radiofrequency accelerator designs. A train of few-optical cycle pulses is predicted with peak powers similar to those of the equivalent conventional FEL amplifier. The role of electron beam energy modulation in these results is explained and the limitations of some simulation codes discussed. It is shown how seeding the FEL interaction using a High Harmonic seed laser can improve the coherence properties of the output

WMAP Haze: Directly Observing Dark Matter?

In this paper we show that dark matter in the form of dense matter/antimatter nuggets could provide a natural and unified explanation for several distinct bands of diffuse radiation from the core of the Galaxy spanning over 12 orders of magnitude in frequency. We fix all of the phenomenological properties of this model by matching to x-ray observations in the keV band, and then calculate the unambiguously predicted thermal emission in the microwave band, at frequencies smaller by 10 orders of magnitude. Remarkably, the intensity and spectrum of the emitted thermal radiation are consistent with--and could entirely explain--the so-called "WMAP haze": a diffuse microwave excess observed from the core of our Galaxy by the Wilkinson Microwave Anisotropy Probe (WMAP). This provides another strong constraint of our proposal, and a remarkable nontrivial validation. If correct, our proposal identifies the nature of the dark matter, explains baryogenesis, and provides a means to directly probe the matter distribution in our Galaxy by analyzing several different types of diffuse emissions.Comment: 16 pages, REVTeX4. Updated to correspond with published version: includes additional appendices discussing finite-size effect

Evolutionary estimation of a Coupled Markov Chain credit risk model

There exists a range of different models for estimating and simulating credit risk transitions to optimally manage credit risk portfolios and products. In this chapter we present a Coupled Markov Chain approach to model rating transitions and thereby default probabilities of companies. As the likelihood of the model turns out to be a non-convex function of the parameters to be estimated, we apply heuristics to find the ML estimators. To this extent, we outline the model and its likelihood function, and present both a Particle Swarm Optimization algorithm, as well as an Evolutionary Optimization algorithm to maximize the likelihood function. Numerical results are shown which suggest a further application of evolutionary optimization techniques for credit risk management