Limits of long wavelength High Harmonic Generation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. [75]-76).Many researchers are pushing for long wavelength driver pulses for High Harmonic Generation (HHG). The advantage of longer wavelengths is that the cut-off of the harmonic spectrum can be increased without the need for large electric fields. Large electric field is undesirable because it leads to large plasma generation which reduces harmonic generation due to phase mismatch and ground state depletion. Most of the current literature on HHG uses the Dipole Approximation for calculation of harmonic spectrum. The physical ramification of the Dipole Approximation is that it neglects the magnetic field component to the driver field. It is well known that a charge moving in a magnetic field experiences a Lorentz force. In HHG, harmonics are generated by recombination of an electron wave packet, moving under the influence of the driver pulse, with its parent atom. The Lorentz force can displace the electron wave packet perpendicular to the direction of polarization and as a result reducing the recombination amplitude. This Lorentz displacement increases as we move towards longer wavelengths and higher intensities. In this thesis, intensity and wavelength limits at which the Lorentz displacement becomes significant have been investigated. By numerically solving the time-dependent Schrödinger equation, we investigate the optimum driver pulse duration for 400 nm, 800 nm and 2 micron driver pulses for a given harmonic for hydrogen.(cont.) It was found that longer wavelength have smaller efficiencies (neglecting phase matching condition). Finally, the harmonic spectrum of Hydrogen driven by 800 nm pulse predicted by analytic Three Step Model (TSM) has been compared with the harmonic spectrum generated by numerical solution of time-dependent Schrödinger equation. It was found, as the current theories predict, that TSM becomes less reliable as the Keldysh Parameter increases. It was also observed that for low harmonic energies, the TSM spectrum deviates from the numerical spectrum by many orders of magnitude.by Siddharth Bhardwaj.S.M

Learned Lock-free Search Data Structures

Non-blocking search data structures offer scalability with a progress guarantee on high-performance multi-core architectures. In the recent past, "learned queries" have gained remarkable attention. It refers to predicting the rank of a key computed by machine learning models trained to infer the cumulative distribution function of an ordered dataset. A line of works exhibits the superiority of learned queries over classical query algorithms. Yet, to our knowledge, no existing non-blocking search data structure employs them. In this paper, we introduce \textbf{Kanva}, a framework for learned non-blocking search. Kanva has an intuitive yet non-trivial design: traverse down a shallow hierarchy of lightweight linear models to reach the "non-blocking bins," which are dynamic ordered search structures. The proposed approach significantly outperforms the current state-of-the-art -- non-blocking interpolation search trees and elimination (a,b) trees -- in many workload and data distributions. Kanva is provably linearizable

Correlation between prolactin, thyroid, LH, FSH, estradiol and progesterone in the infertile women

Background: An important global health issue, infertility affects a couple’s social, psychological, economic, and sexual well-being. A variety of issues stemming from abnormal hypothalamus pituitary ovarian axis dysfunction make up the hormonal diseases of the female reproductive system. The aim of the study was to find correlation between prolactin, thyroid, LH, FSH, estradiol and progesterone in the infertile women. Methods: Present study was hospital based descriptive, cross-sectional study. 150 infertile women were required in sample size. Serum LH, FSH, estradiol was measured on day 2 of menstrual cycle and also serum TSH and serum progesterone on day 21. Results: Around one third (38%) of the cases was married since more than 10 years. Majority 108 (72%) had primary infertility and 50% of the women had history of irregular menstrual cycles. There was significant positive correlation between TSH and prolactin (p value <0.05) and significant negative correlation of TSH with FSH and LH (p value <0.05) and there was insignificant negative correlation of TSH with estrogen (D2) and progesterone (D21). The mean value of TSH in our study was 7.47±1.82 μIU/ml. Conclusions: TSH has strong positive co-relation between prolactin, FSH and LH indicating role in female infertility. These hormonal evaluations allow a routine etiological approach to the diagnosis of infertility.

Morbidity Patterns in Oncology Patients at FMRI, Gurgaon:A Hospital Based Study at a New Tertiary Care Institute

Objective: This study aims to analyze the patterns of morbidity amongst cancer patients attending a tertiary care hospital.Materials and Methods: Data were collected from various departments dealing in cancer care. Patient’s data were categorized according to diagnosis and place of residence.Results: A total of 1490 new cancer patients were registered. Out of these 1140 were Indians from 22 different states {males= 609 (53.4%) and females= 531 (46.6%)} and remaining 350 patients were from 27 different countries {males= 223 (63.7%) and females=127 (36.3%)}. The five most common cancer site groups amongst all males (n=832) were digestive organs (18.6%) followed by lymphoid, hematopoietic and related tissue (16.8%);  respiratory intrathoracic organs (14.1%); then eye, brain and other parts of central nervous system (11.4%) and lip, oral cavity and  pharynx (9.5%)  and in all females (n=658) the most common cancer site were breast (31.5%) followed by  genital organs (17.3%); digestive organs (11.2%); lymphoid, hematopoietic and related tissue (9.3%) and eye, brain and other parts of nervous system (9.0%).Conclusions:  The present study highlights the pattern of cancer among patients in a corporate tertiary health care institute. There is therefore an inherent bias, the leading sites of malignancies amongst Indian males and females varied from that in the Western population; this could be attributed to various cultural, environmental factors, life style, genetic factors etc. in different regions of India and different nations of the world.

High-order harmonic generation in Xe, Kr, and Ar driven by a 2.1-\mu m source: high-order harmonic spectroscopy under macroscopic effects

We experimentally and numerically study the atomic response and pulse propagation effects of high-order harmonics generated in Xe, Kr, and Ar driven by a 2.1-\mu m infrared femtosecond light source. The light source is an optical parametric chirped-pulse amplifier, and a modified strong-field approximation and 3-dimensional pulse propagation code are used for the numerical simulations. The extended cutoff in the long-wavelength driven high-harmonic generation has revealed the spectral shaping of high-order harmonics due to the atomic structure (or photo-recombination cross-section) and the macroscopic effects, which are the main factors of determining the conversion efficiency besides the driving wavelength. Using precise numerical simulations to determine the macroscopic electron wavepacket, we are able to extract the photo-recombination cross-sections from experimental high-order harmonic spectra in the presence of macroscopic effects. We have experimentally observed that the macroscopic effects shift the observed Cooper minimum of Kr from 80 eV to 60-70 eV and wash out the Cooper minimum of Ar. Measured high-harmonic conversion efficiencies per harmonic near the cutoff are ~10^{-9} for all three gases.Comment: 19 pages, 8 figure

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Measurement of associated Z plus charm production in proton-proton collisions at root s=8TeV

A study of the associated production of a Z boson and a charm quark jet (Z + c), and a comparison to production with a b quark jet (Z + b), in pp collisions at a centre-of-mass energy of 8 TeV are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb(-1), collected with the CMS detector at the CERN LHC. The Z boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of c or b flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with pT(l) > 20 GeV, vertical bar eta(l)vertical bar 25 GeV and vertical bar eta(jet)vertical bar Z + c + X) B(Z -> l(+)l(-)) = 8.8 +/- 0.5 (stat)+/- 0.6 (syst) pb. The ratio of the Z+c and Z+b production cross sections is measured to be sigma(pp -> Z+c+X)/sigma (pp -> Z+b+X) = 2.0 +/- 0.2 (stat)+/- 0.2 (syst). The Z+c production cross section and the cross section ratio are also measured as a function of the transverse momentum of theZ boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.Peer reviewe