Frequency-Doubling of Femtosecond Pulses in “Thick” Nonlinear Crystals With Different Temporal and Spatial Walk-Off Parameters

We present a comparative study on frequency-doubling characteristics of femtosecond laser pulses in thick nonlinear crystals with different temporal and spatial walk-off parameters. Using single-pass second harmonic generation (SHG) of 260 fs pulses at 1064 nm from a high-average-power femtosecond Yb-fiber laser in 5-mm-long crystals of β-BaB2O4 (BBO) and BiB3O6 (BIBO), we find that for comparable values of temporal and spatial walk-off parameters in each crystal, the optimum focusing condition for SHG is more strongly influenced by spatial walk-off than temporal walk-off. It is also observed that under such conditions, the Boyd and Kleinman theory commonly used to define the optimum focusing condition for frequency-doubling of cw and long-pulse lasers is also valid for SHG of ultrafast lasers. We also investigate the effect of focusing on the spectral, temporal, and spatial characteristics of the second harmonic (SH) radiation, as well as angular acceptance bandwidth for the SHG process, under different temporal and spatial walk-off conditions in the two crystalsPeer ReviewedPostprint (author's final draft

MENGGUNAKAN METODE DISKUSI UNTUK MENINGKATKAN KEMAMPUAN MENULIS PADA SISWA KELAS IV SD NEGERI NEUHEUN KABUPATEN ACEH BESAR

Banda Ace

Chirped Pulse Control of Raman Coherence in Atoms and Molecules

A novel chirped pulse control scheme is presented based on Coherent Anti-Stokes Raman Spectroscopy (C-CARS) aiming at maximizing the vibrational coherence in atoms and molecules. The scheme utilizes chirping of the three incoming pulses, the pump, the Stokes and the probe, in the four-wave mixing process of C-CARS to fulfill the adiabatic passage conditions. The derivation of the scheme is based on simplifying the four-level system into a 'super-effective' two level system via rotating wave approximation and adiabatic elimination of the excited state manifold. The robustness, spectral selectivity and adiabatic nature of C-CARS method may prove useful for sensing, imaging, and detection. It is demonstrated that the selectivity in excitation of vibrational degrees of freedom can be controlled by carefully choosing the spectral chirp rate of the pulses. The C-CARS control scheme is applied to a surrogate methanol molecule to generate an optimal anti-Stokes signal backscattered from a cloud of molecules a kilometer away. The theory is based on the solution of the coupled Maxwell-Liouville von Neumann equations and focuses on the quantum effects induced in the target molecules by the control pulse trains. The propagation effects of pulses through the medium are evaluated and the buildup of the molecular-specific anti-Stokes signal is demonstrated numerically. A deep learning technique, using Convolutional Neural Networks (CNN), is implemented to characterize the control pulses and evaluate time-dependent phase characteristics from them. The effects of decoherence induced by spontaneous decay and collisional dephasing are also examined. Additionally, we present the technique of Fractional Stimulated Raman Adiabatic Passage (F-STIRAP) and demonstrate that it can be utilized for remote detection in a multi-level system by creation of a maximally coherent superposition state

Surface plasmon induced quantum interference at meta-material interface

In this work we investigate quantum interference in a four-level atom coupled to a negative index meta-material (NIMM) plasmonic reservoir that supports both TE and TM polarized surface plasmons (SP). This provides more options to control SP interaction with emitters and hence more control of spontaneous emission decays and spectrum. The spectrum depends critically on parameters like the reservoir parameters, mode frequency, frequency dependent electric permittivity and magnetic permeability, and the location of the atom. We report orders of magnitude enhancement in the reservoir-modified decays and spectrum compared to free space case. The rich atomic and plasmonic parameters provide a wide range of flexibility and more options to control emission spectrum that suits practical applications.Comment: 30 pages , 8 figures , research wor

INTERLEUKIN-18 GENE POLYMORPHISM AND SOME RISK FACTORS IN IRAQI PATIENTS WITH BREAST CANCER

Objective: Breast cancer is the most diagnosed cancer in women, which leads to death in a lot of women with breast cancer. The major risk factors associated with breast cancer risk related to family history, age, clinical history, lifestyle factors, long-period hormonal exposure, and single nucleotide polymorphisms in many genes showed possible links with breast cancer incidence risk in different people populations. Our study aimed to figure out the correlation between smoking, lodging and family history, and other factors with the risk of breast cancer.Methods: Blood sample from female patients with breast cancer and healthy individuals were collected and subjected to tetra-amplification refractory mutation system–polymerase chain reaction (T-ARMS-PCR) technique for −607 C/A mutation of an interleukin (IL-18) gene and SPSS 18 software analyzed the results statically.Results: Results showed no association between lodging and smoking with risk of breast cancer, (p>0.05), while the association between the risk and family history were obvious (p<0.05).Conclusion: The results obtained by T-ARMS-PCR technique did not show the association between −607 C/An alternation of IL-18 gene and breast cancer (p>0.05) in the individuals examined in our study.Keywords: Interleukin-18, Gene, Polymorphism, Tetra-amplification refractory mutation system–polymerase chain reaction, Mutations

A graph-based unified technique for computing and representing co-efficients over finite fields

This paper presents the generalized theory and an efficient graph-based technique for the calculation and representation of coefficients of multivariate canonic polynomials over arbitrary finite fields in any polarity. The technique presented for computing coefficients is unlike polynomial interpolation or matrix-based techniques and takes into consideration efficient graph-based forms which can be available as an existing resource during synthesis, verification, or simulation of digital systems. Techniques for optimization of the graph-based forms for representing the coefficients are also presented. The efficiency of the algorithm increases for larger fields. As a test case, the proposed technique has been applied to benchmark circuits over GF2. The experimental results show that the proposed technique can significantly speed up execution time. Finite or Galois fields, decision diagrams, coefficients, polynomials

Evaluating the tracking e-Files prototype project based on the task technology fit model

Locating files in an exact time is considered one of the greatest problems and the tedious process in universities nowadays. This problem becomes greater when the university has a large number of departments and transactions, as well as the documents are moving from one department to another. Especially, developing countries that have many problems and unstable environment and that may lead to lost or damage the important documents that influence on the decision making. Furthermore, the traditional manner not only wasted the time and energy, but also the paper cost for printing copies of required file. And with the advancement of technology and the increase of Internet users, documents are still being sent in Iraqi universities manually between departments. Although the higher education and scientific research ministry was recommended the public universities for using modern technologies during the daily transactions between the departments or amongst the units.  Therefore, this study sought to design and evaluate the prototype system which tracks movements of the documents from one department to another as well as check the completion rate for each department. For providing opportunities to assess how well the use of e-file tracking system meets the needs of management units in universities. The systems implementation research notes the need to fit between tasks, technologies and users.  Thus, this empirical study utilized the task technology fit model for this purpose. The results from selected participants indicated that all the factors significant effect on the employee’s performance in E-file Tracking System, excepted, task characteristics. This study will be contributed to reduce the corruption and enhance the transparency and help the decision-makers make the right decision at the right time

Is lumbar facet joint tropism developmental or secondary to degeneration? An international, large-scale multicenter study by the AOSpine Asia Pacific Research Collaboration Consortium

published_or_final_versio