Constraints in the market chains for export of Sudanese sheep and sheep meat to the Middle East

The objective of this publication is to analyse the causes of declining market share of Sudanese sheep and sheep meat in the Middle East market, especially in the Saudi market, by examining the constraints in the export supply chains. The following major factors are hypothesized to explain constraints limiting export to Saudi Arabia: there are specific export requirements for quality assurance and safety of Sudanese sheep and sheep meat, and there are rules and procedures in place in Sudan to test, certify and assure supply of quality and safe animals and meat to the Saudi importers. However, these are inadequate and inefficient to match the SPS standards of the importing country; multiple intermediaries are involved along the market chains resulting in several points of taxation along the value chains; this leads to increased transaction costs which lower competitiveness; domestic livestock markets are spatially integrated and therefore can respond quickly to varying import demand requirements. A market chain framework linking producers and importers through the intermediate markets and actors was used to analyse these factors. Both secondary and primary survey data were used to generate evidence on these factors

Fidelity of flight control systems in a real-time optimal trajectory planner

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991.Includes bibliographical references (leaves 56).by Toni El-Dirani.M.S

The Effect of Age on Corneal Topographic Indices, Keratometry and Visual Acuity After Combined Intrastromal Corneal Ring Segment (ICRS) Implantation and Corneal Crosslinking

We aimed to assess age-related changes in corneal topographic indices, keratometry and visual acuity after sequential intracorneal ring segment implantation (ICRS) and crosslinking (CXL). This was a retrospective matched case-control series including 26 eyes of patients ≤18 years as the cases and 26 eyes of adult patients as control. All eyes received ICRS+CXL for progressive keratoconus. Eyes were matched regarding the keratoconus parameters and the treatment (type, number and thickness of ICRS). Data was analyzed for refractive and topographic values [uncorrected and corrected distance visual acuity (UDVA; CDVA) sphere; cylinder; spherical equivalent; maximum keratometry (Kmax); flat keratometry (Kflat); steep keratometry (Ksteep); all 7 pentacam topographic indices] preoperatively and one year postoperatively. Preoperatively, there was no significant difference for any refractive, clinical or topographic parameters between the groups except for vertical asymmetry. After one year, children had a significantly higher improvement in Ksteep (3.05D) than adults (2.10D; P=0.036) and a trend to significance for Kflat (2.7D compared to 1.78D, respectively; P=0.081). UDVA improved by 4.3 ETDRS lines in children compared to 3.3 ETDRS lines in adults and CDVA improved by 1.7 ETDRS lines in children compared to 1.2 ETDRS lines in adults, but with no statistical significance. The effects on keratometry indicated that corneal response after ICRS and CXL for keratoconus is more pronounced in young patients than adults. This assumption is also supported by functional improvement and by the fact that a few eyes (5) of some very young patients (<13years) showed highly remarkable improvements after surgery (higher than any adult eye)

Factors associated with female genital mutilation : A systematic review and synthesis of national, regional, and community-based studies.

Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Acknowledgment We would like to acknowledge the assistance of Ms. Sandra Kahwaji and Ms. Jana Abu Ayash for their help in the title and abstract screening of articles. We thank Dr. Sawsan Abdulrahim for insightful comments and edits on preliminary drafts.Peer reviewedPublisher PD

The global prevalence of female genital mutilation/cutting : A systematic review and meta-analysis of national, regional, facility, and school-based studies

Funding: The authors received no specific funding for this work. Acknowledgments We thank Dr. Marie-Claire Rebeiz, Mrs. Tanya Khoury, and Ms. Sara Mansour who verified the data in the tables.Peer reviewedPublisher PD

Waveguide optical parametric amplifiers in silicon nitride with 2D graphene oxide films

Optical parametric amplification (OPA) represents a powerful solution to achieve broadband amplification in wavelength ranges beyond the scope of conventional gain media, for generating high-power optical pulses, optical microcombs, entangled photon pairs and a wide range of other applications. Here, we demonstrate optical parametric amplifiers based on silicon nitride (Si3N4) waveguides integrated with two-dimensional (2D) layered graphene oxide (GO) films. We achieve precise control over the thickness, length, and position of the GO films using a transfer-free, layer-by-layer coating method combined with accurate window opening in the chip cladding using photolithography. Detailed OPA measurements with a pulsed pump for the fabricated devices with different GO film thicknesses and lengths show a maximum parametric gain of ~24.0 dB, representing a ~12.2 dB improvement relative to the device without GO. We perform a theoretical analysis of the device performance, achieving good agreement with experiment and showing that there is substantial room for further improvement. This work represents the first demonstration of integrating 2D materials on chips to enhance the OPA performance, providing a new way of achieving high performance photonic integrated OPA by incorporating 2D materials.Comment: 38 pages, 8 figures, 80 reference

Suppression of Parasitic Nonlinear Processes in Spontaneous Four-Wave Mixing with Linearly Uncoupled Resonators

We report on a signal-to-noise ratio characterizing the generation of identical photon pairs of more than 4 orders of magnitude in a ring resonator system. Parasitic noise, associated with single-pump spontaneous four-wave mixing, is essentially eliminated by employing a novel system design involving two resonators that are linearly uncoupled but nonlinearly coupled. This opens the way to a new class of integrated devices exploiting the unique properties of identical photon pairs in the same optical mode

REVIEW ON CHEMICAL CONSTITUENTS AND BIOLOGICAL ACTIVITIES OF GENUS FERULA

Genus Ferula comprises about 220 species of flowering plants belonging to family Apiaceae, distributed in the Mediterranean region and Asia and used in the treatment of different diseases as anti-oxidant, aphrodisiac, carminative, antinociceptive, anti-depressant, antibacterial, anti-fungal, anti-leishmanial, and anti-inflammatory. Moreover, species of this plant are used for dizziness, asthma, bronchitis, and gastrointestinal discomfort. It was reported that all the pharmacological effects of these plants are due to the presence of different phenolic constituents including flavonoids, sesquiterpenes, coumarins and polysulfides. Sesquiterpene coumarins were responsible for the anti-inflammatory and anti-cancer activities by blocking the 5-lipoxygenase enzyme that catalyzes the biosynthesis of leukotrienes (LTs) being a group of lipid mediators of inflammation . This review covers most of the identified chemical constituents of plants from the genus Ferula reported in literature between 2001 and 2023. In addition, the biological activities of the different species of genus Ferula are presented

Annealing-free Si3N4 frequency combs for monolithic integration with Si photonics

International audienceSilicon-nitride-on-insulator (SiNOI) is an attractive platform for optical frequency comb generation in the telecommunication band because of the low two-photon absorption and free carrier induced nonlinear loss when compared with crystalline silicon. However, the high-temperature annealing that has been used so far for demonstrating Si3N4-based frequency combs made the co-integration with silicon-based optoelectronics elusive, thus reducing dramatically its effective complementary metal oxide semiconductor (CMOS) compatibility. We report here on the fabrication and testing of annealing-free SiNOI nonlinear photonic circuits. In particular, we have developed a process to fabricate low-loss, annealing-free, and crack-free Si3N4 740-nm-thick films for Kerr-based nonlinear photonics featuring a full process compatibility with front-end silicon photonics. Experimental evidence shows that micro-resonators using such annealing-free silicon nitride films are capable of generating a frequency comb spanning 1300-2100 nm via optical parametrical oscillation based on four-wave mixing. This work constitutes a decisive step toward time-stable power-efficient Kerr-based broadband sources featuring full process compatibility with Si photonic integrated circuits (Si-PICs) on CMOS-.lines