Towards On-Chip Self-Referenced Frequency-Comb Sources Based on Semiconductor Mode-Locked Lasers.

Miniaturization of frequency-comb sources could open a host of potential applications in spectroscopy, biomedical monitoring, astronomy, microwave signal generation, and distribution of precise time or frequency across networks. This review article places emphasis on an architecture with a semiconductor mode-locked laser at the heart of the system and subsequent supercontinuum generation and carrier-envelope offset detection and stabilization in nonlinear integrated optics

Effect of nascent entrepreneurs' training on their stress: the role of gender and participants' interaction

Purpose – A career in entrepreneurship is stressful, especially during the start-up phase. Training programs for these nascent entrepreneurs are designed to improve entrepreneurial competencies and, more generally to generate learnings. Although learning outcomes can reduce stress, the conditions under which this can happen are not fully understood. The study looks particularly at the effect of learning, interaction with other participants and gender. Design/methodology/approach – A six-month three-wave longitudinal study of 120 nascent entrepreneurs has been conducted to investigate the before-and-after effects of training on stress reduction. The training is specially designed to develop competencies, share knowledge about business creation and support the development of the project, not to reduce per se stress. Findings – The training has no direct effect on stress levels. However, results indicate that interacting with others has a positive moderating effect on training as stress reduction, just as gender has. Specifically, women reduce their stress through training while men see theirs increasing. The authors conclude that breaking isolation through training is a relevant way to reduce entrepreneurial stress for nascent entrepreneurs. Research limitations/implications – Training programs offer different ways to deliver the learning content (online, in cohorts, in the continuous entrance, etc.). The findings of this study suggest ensuring that the participants will have opportunities to interact with others as it reduces the stress on nascent entrepreneurs. Nevertheless, the authors cannot demonstrate that this has a long-term effect as our timeframe is limited to six months. Originality/value – This research investigates the stress-reduction effect of training, which is not a common outcome studied related to training. This highlights the importance of looking at other more distal outcomes as nascent entrepreneurs may seek other peripheral outcomes from training, like seeking a sense of belonging or wanting to break isolation

Upregulated IL-32 expression and reduced gut short chain fatty acid caproic acid in people living with HIV with subclinical atherosclerosis

Despite the success of antiretroviral therapy (ART), people living with HIV (PLWH) are still at higher risk for cardiovascular diseases (CVDs) that are mediated by chronic inflammation. Identification of novel inflammatory mediators with the inherent potential to be used as CVD biomarkers and also as therapeutic targets is critically needed for better risk stratification and disease management in PLWH. Here, we investigated the expression and potential role of the multi-isoform proinflammatory cytokine IL-32 in subclinical atherosclerosis in PLWH (n=49 with subclinical atherosclerosis and n=30 without) and HIV- controls (n=25 with subclinical atherosclerosis and n=24 without). While expression of all tested IL-32 isoforms (α, β, γ, D, ϵ, and θ) was significantly higher in peripheral blood from PLWH compared to HIV- controls, IL-32D and IL-32θ isoforms were further upregulated in HIV+ individuals with coronary artery atherosclerosis compared to their counterparts without. Upregulation of these two isoforms was associated with increased plasma levels of IL-18 and IL-1β and downregulation of the atheroprotective protein TRAIL, which together composed a unique atherosclerotic inflammatory signature specific for PLWH compared to HIV- controls. Logistic regression analysis demonstrated that modulation of these inflammatory variables was independent of age, smoking, and statin treatment. Furthermore, our in vitro functional data linked IL-32 to macrophage activation and production of IL-18 and downregulation of TRAIL, a mechanism previously shown to be associated with impaired cholesterol metabolism and atherosclerosis. Finally, increased expression of IL-32 isoforms in PLWH with subclinical atherosclerosis was associated with altered gut microbiome (increased pathogenic bacteria; Rothia and Eggerthella species) and lower abundance of the gut metabolite short-chain fatty acid (SCFA) caproic acid, measured in fecal samples from the study participants. Importantly, caproic acid diminished the production of IL-32, IL-18, and IL-1β in human PBMCs in response to bacterial LPS stimulation. In conclusion, our studies identified an HIV-specific atherosclerotic inflammatory signature including specific IL-32 isoforms, which is regulated by the SCFA caproic acid and that may lead to new potential therapies to prevent CVD in ART-treated PLWH

Low-loss and nonlinear silicon-based integrated photonic circuits

Photonic integrated circuits enable tight integration of optical components used as building blocks for much larger optical systems, similarly to electronic integrated circuits. In particular, silicon-based photonics can leverage the yield and scaling technology improvements that also benefit the electronics industry. Moreover, photonic integrated circuits can reduce the power consumption in communication and computation applications, and open the door to new applications in sensing and ranging. The design of linear and nonlinear passive photonic components is key to the performance improvement of integrated photonics. In the first part of this dissertation, we present a platform for creating on-chip frequency combs using materials with a large third-order nonlinear index. Specifically, using chalcogenide glass waveguides, we produce a frequency comb spanning greater than an octave bandwidth using input optical pulses on the picojoule level. In the second part, we discuss fabrication processes and optical designs to improve the fiber-to-chip coupling loss, which is a limiting factor in large-scale optical switch applications. We present the design of an adiabatic evanescent coupler that is polarization diverse and has a bandwidth greater than 100 nm in the O band. Our design achieves better than 2 dB insertion loss and is compatible with different photonic fabrication processes

Gender differences in self-confidence in entrepreneurial skills: A solution through select professional and educational activities?

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High-Q And Low-Loss Chalcogenide Waveguide For Nonlinear Supercontinuum Generation

We report on wafer-scale processing of GeSbS-based chalcogenide waveguides on silicon substrates. High Q-factor (106), low propagation loss (0.2 dB/cm), and supercontinuum generation in a 2-cm-long waveguide with 120 pJ pulses are demonstrated

Large Bandwidth Silicon Nitride Spot-Size Converter For Efficient Supercontinuum Coupling To Chalcogenide Waveguide

Silicon nitride spot-size converters were fabricated in a damascene process to improve the performance of supercontinuum generation in arsenic-free chalcogenide waveguides. Supercontinuum generation covering 950-1750 nm with 200 pJ pulses is demonstrated

May Business Mentors Act as Opportunity Brokers and Enablers Among University Students?

Networks are recognized as a central component of the entrepreneurial process, in particular with regard to opportunity identification and exploitation. In this study, we specifically analyze the role of mentors who are in business as opportunity brokers and enablers among university students with entrepreneurial intentions. Our investigation on 1022 students from 13 French-language universities based in Canada, France, Belgium and Algeria indicates that mentors in business, contrary to other mentors, support opportunity identification and exploitation among university students. Although student gender, entrepreneurial experience and education have a more pronounced effect, mentoring is the only element that can be controlled for through the creation of formal support programs. These results call on public authorities, and universities in particular, to implement formal mentoring programs to support students who are interested in starting their own business, and who would not otherwise have access to business mentors in their environment

Integrated Thin-Film Lithium-Niobate Waveguides On Silicon For Second-Harmonic Generation Pumped At 1875 Nm

A thin-film periodically-poled lithium niobate (PPLN) on silicon wavelength converter is demonstrated for application in carrier-envelope offset stabilization. Supercontinuum generation, amplified at about 1900 nm wavelength, is used to generate second harmonic generation

Entrepreneurial Intentions of University Students: An International Comparison between African, European and Canadian students

The purpose of this study is to compare the entrepreneurial intentions of university students in North Africa (Algeria) with those of students in Canada and Europe (France and Belgium), and to examine differences with regard to psychological, sociocultural and economic factors influencing these intentions. Analyses on the sample as a whole confirm the relevancy of the theory of planned behaviour (TPB) proposed by Ajzen (1991). When we differentiate among cultural groups, results were fairly similar for Canadian and European students. However, no TPB elements were significant for the Algerian students, or more significant than the control variables. We discuss the need to consider cultural factors to explain entrepreneurial intentions. Moreover, given the socioeconomic climate in Algeria, we hypothesise that among Algerian university students, entrepreneurship is motivated by necessity rather than opportunity