Demonstration of an integrated LiNbO3 Synchronized Double Phase Modulator and its Applications to Dual-Pump Fiber Optical Parametric Amplifiers and Wavelength Converters

International audienceWe report the fabrication of an integrated LiNbO3 Y-junction synchronized double phase modulator fully packaged for RF-application up to 40 GHz. This optical modulator allows for delivering simultaneously counter-phase high-speed modulation and coupling for two input channels. It was designed for application to fiber-optical parametric amplifier and wavelength converters for suppressing idler spectral broadening and signal gain distortion caused by phase modulation itself. With this component, Idler spectral broadening suppression is experimentally demonstrated over all the parametric gain band of a twopump parametric amplifier operating in the 1.55 µm region. In addition, we present a useful technique for straightforward and full coupling of the pumps and the signal

The Impact of Augmented Reality on Vocabulary Acquisition in Iran

This paper explores gender differences among the students that used augmented reality (AR) in Iranian secondary schools. Vocabulary learning is considered as basic in foreign language acquisition, and it has a great importance in Iranian language education. Participants of the study were both female and male students due to the fact Iranian schools are considered gender-based. The Iranian education system is not based on co-education, and for this reason male and female students attend different schools. The current study is based on experimental design, and data was collected using pre-test and post-test. The findings show that there are no differences in learning English vocabulary due to gender among the Iranian students who use the AR-based approach

The effect of corporate social responsibility on sustainable development with the mediating role of employee participation in knowledge-based companies

BACKGROUND AND OBJECTIVES: Sustainable development is a process that envisions a desirable future for human societies in which living conditions and resource use meet human needs without compromising the integrity, beauty, and stability of vital systems. Knowledge-based companies today are among those companies that act as factories for converting knowledge into goods and services. In this regard, organizational social responsibility can be the basis for the sustainable development of companies and organizations. Therefore, this research aims are to examine the role of the organization’s social responsibility for sustainable development in terms of mediating the participation of employees of knowledge-based companies.                                                                                                                                METHODS: This research is applied in terms of purpose, descriptive survey and correlation in terms of method. Field and library methods, literature reviews, and standard questionnaires were used to collect information. The statistical population consisted of 578 senior and middle managers of knowledge-based companies in the Science and Technology Park of Sharif University of Technology, Tehran- Iran, and 231 people were sampled using Cochran's formula method and stratified random sampling. A standard questionnaire was also used to collect information. The validity of the questionnaire was checked and confirmed using convergent and divergent validity and confirmatory factor analysis and its reliability using Cronbach's alpha coefficient, joint and combined reliability. Finally, the collected data was analyzed using SPSS and smartPLS software’s.FINDINGS: Based on the results of the Kolmogorov-Smirnov test, the significance of this test was calculated for all indicators less than 0.05 and 0.000, and due to the lack of normal distribution of the data, the smart PLS software was used. The overall fitting criterion was calculated to be 0.551, which means that the model fits well. When testing the main hypothesis, a coefficient of 0.408 was calculated, showing that employee participation explains 40% of the impact of social responsibility on sustainable development. The path coefficient of the sub-hypotheses for these relationships is above 0.5 and the significance is above 1.96. It can be said that the sub-hypotheses of the research are confirmed.CONCLUSION: According to the indicators obtained, the organization’s social responsibility positively and significantly impacts sustainable development and employee participation. The positive role of employee participation in sustainable development was also confirmed. Finally, the results showed that employee participation can mediate the impact of social responsibility on sustainable development

In Situ Proteolysis to Generate Crystals for Structure Determination: An Update

For every 100 purified proteins that enter crystallization trials, an average of 30 form crystals, and among these only 13–15 crystallize in a form that enables structure determination. In 2007, Dong et al reported that the addition of trace amounts of protease to crystallization trials—in situ proteolysis—significantly increased the number of proteins in a given set that produce diffraction quality crystals. 69 proteins that had previously resisted structure determination were subjected to crystallization with in situ proteolysis and ten crystallized in a form that led to structure determination (14.5% success rate). Here we apply in situ proteolysis to over 270 new soluble proteins that had failed in the past to produce crystals suitable for structure determination. These proteins had produced no crystals, crystals that diffracted poorly, or produced twinned and/or unmanageable diffraction data. The new set includes yeast and prokaryotic proteins, enzymes essential to protozoan parasites, and human proteins such as GTPases, chromatin remodeling proteins, and tyrosine kinases. 34 proteins yielded deposited crystal structures of 2.8 Å resolution or better, for an overall 12.6% success rate, and at least ten more yielded well-diffracting crystals presently in refinement. The success rate among proteins that had previously crystallized was double that of those that had never before yielded crystals. The overall success rate is similar to that observed in the smaller study, and appears to be higher than any other method reported to rescue stalled protein crystallography projects

In Situ Proteolysis to Generate Crystals for Structure Determination: An Update

For every 100 purified proteins that enter crystallization trials, an average of 30 form crystals, and among these only 13–15 crystallize in a form that enables structure determination. In 2007, Dong et al reported that the addition of trace amounts of protease to crystallization trials—in situ proteolysis—significantly increased the number of proteins in a given set that produce diffraction quality crystals. 69 proteins that had previously resisted structure determination were subjected to crystallization with in situ proteolysis and ten crystallized in a form that led to structure determination (14.5% success rate). Here we apply in situ proteolysis to over 270 new soluble proteins that had failed in the past to produce crystals suitable for structure determination. These proteins had produced no crystals, crystals that diffracted poorly, or produced twinned and/or unmanageable diffraction data. The new set includes yeast and prokaryotic proteins, enzymes essential to protozoan parasites, and human proteins such as GTPases, chromatin remodeling proteins, and tyrosine kinases. 34 proteins yielded deposited crystal structures of 2.8 Å resolution or better, for an overall 12.6% success rate, and at least ten more yielded well-diffracting crystals presently in refinement. The success rate among proteins that had previously crystallized was double that of those that had never before yielded crystals. The overall success rate is similar to that observed in the smaller study, and appears to be higher than any other method reported to rescue stalled protein crystallography projects

Theoretical study of gain distortions in dual-pump fiber optical parametric amplifiers

International audienceWe study analytically and numerically the small signal gain in dual-pump fiber optical parametric amplifiers by including the phase modulation of the pump waves needed for practically increasing the stimulated Brillouin scattering threshold. As for the single-pump case, we show that large signal gain distortions are generated under co-phase modulation, which depend on the rise/fall time of the phase modulation and on the fiber dispersion slope. However, it is clearly confirmed that the counter-phase modulation scheme allows to effi-ciently suppress these gain distortions over the whole flat gain region. In addition, we demonstrate through realistic numerical simulations that this useful technique overcomes the additional impact of pump-phase modulation to amplitude modulation conversion and zero-dispersion wavelength variations

Sensitive and Accurate Dispersion Map Extraction of HNLFs by Frequency Tuning of a Degenerate FWM

A sensitive and accurate method for dispersion map extraction along an arbitrarily profiled highly nonlinear fiber (HNLF) is proposed. High sensitivity is achieved by positioning the wavelength of a signal at the band edge of the modulation instability (MI) spectrum generated by an intense degenerate four wave mixing (FWM) pump. In doing so, the to-be-extracted dispersion fluctuations leave a more drastic effect on the FWM-generated power since they either inflate or deflate theMI spectrum. The accuracy of the method is increased by monitoring the distribution of power along the fiber. Once the power distribution is measured along the fiber, dispersion map of the HNLF is extracted using an appropriate inverse algorithm, which reconstructs the dispersion with a highlevel ofaccuracy.

System performances of fiber optical parametric amplifiers

International audienceThe research field of fiber optical parametric amplifiers has steadily expanded over the last two decades as a host of all-optical signal processing techniques have been demonstrated in nonlinear optical fibers such as wavelength conversion, optical regeneration, optical switching, limiting, buffering, and sampling. This article reviews the system performances of theses parametric devices such as gain bandwidth, focuses on the main limitations and demonstrates efficient techniques for suppressing the

Mapping Dispersion Fluctuations along Optical Fibers Using Brillouin Probing and a Fast Analytic Calculation

A simple analytic formula is derived to extract tiny dispersion fluctuations along highly nonlinear fibers from distributed measurements of parametric gain. A refined BOTDA scheme, suitable to track Kerr processes, enables low noise measurements