Ultra-low threshold deep ultraviolet generation in a hollow-core fiber.

Tunable ultrashort pulses in the ultraviolet spectral region are in great demand for a wide range of applications, including spectroscopy and pump-probe experiments. While laser sources capable of producing such pulses exist, they are typically very complex. Notably, resonant dispersive-wave (RDW) emission has emerged as a simple technique for generating such pulses. However, the required pulse energy used to drive the RDW emission, so far, is mostly at the microjoule level, requiring complicated and expensive pump sources. Here, we present our work on lowering the pump energy threshold for generating tuneable deep ultraviolet pulses to the level of tens of nanojoules. We fabricated a record small-core antiresonant fiber with a hollow-core diameter of just 6 µm. When filled with argon, the small mode area enables higher-order soliton propagation and deep ultraviolet (220 to 270 nm) RDW emission from 36 fs pump pulses at 515 nm with the lowest pump energy reported to date (tens of nanojoules). This approach will allow the use of low-cost and compact laser oscillators to drive nonlinear optics in gas-filled fibers for the first time to our knowledge.

Knowledge and handling practices for raw hen's eggs during purchase, preparation, storage, and consumption: a cross sectional study.

The study aimed to assess the hen's eggs knowledge, handling practices, and consumption among Palestinian consumers using the cross-sectional survey design. Online questionnaire was sent via social media platforms including well-known Facebook and WhatsApp groups in West bank, Gaza and Jerusalem, along with an invitation explaining the research objectives and the voluntary participation. The online questionnaire consisted of three main sections: socio demographic, knowledge and practices for hen's eggs during purchase, preparation, storage, and consumption. The items were developed based on previous literature and international guidelines for hen's eggs purchase and handling, and subjected to content validity process, followed by a pilot study to determine the reliability of the questionnaire using Cronbach's alpha test. The final data were analysed based on the dichotomous Rach model for knowledge and polytomous Rasch model for practices using Winsteps version 5.1.3. The Rasch SPSS output interval data files were used in the inferential analyses tests (one-way ANOVA test and independent samples t-test). The Rasch analysis showed that on average the participants had quite low level of knowledge of hen's eggs consumption safety, (person ability Mean 0.10 logit). The item difficulty measures ranged between + 1.65 (most difficult) and - 2.24 logit (easiest). It was not easy for the participants to endorse the items pertaining their practices in handling the hen's eggs during purchase, preparation, storage and consumption, (person ability Mean - 0.11 logit). The item difficulty measures ranged between + 2.68 logits (most difficult) to - 2.45 logit (easiest). In addition, female participants significantly outperformed males in knowledge scores; and the level of hen's eggs hygiene practices and storage during purchase depended on participants' knowledge level. The research recommended interventional programs to enhance Palestinians' awareness and knowledge about hen's eggs knowledge, handling practices, and consumption. Further quantitative and qualitative research studies were also recommended.