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The influence of both the natural convection and end-effects on Rayleigh streaming pattern in a simple standing-wave thermoacoustic engine is investigated experimentally at different acoustic levels. The axial mean velocity inside the engine is measured using both Laser Doppler Velocimetry and Particle Image Velocimetry. The mean flow patterns are categorized in three different regions referred to as "cold streaming" region, "hot streaming" region, and "end-effects" region. In the cold streaming region, the dominant phenomenon is Rayleigh streaming and the mean velocity measurements correspond well with the theoretical expectations of Rayleigh streaming at low acoustic levels. At higher acoustic levels, the measurements deviate from the theoretical expectations which complies with the literature. In the hot streaming region, temperature measurements reveal that the non-uniformity of the resonator wall temperature is the origin of natural convection flow. Velocity measurements show that natural convection flow superimposes on the Rayleigh streaming flow so that the measured mean velocity deviates from the theoretical expectations of Rayleigh streaming. In the last region, the measured mean velocity is very different from Rayleigh streaming due to the combined effects of both the flow disturbances generated near the extremity of the stack and the natural convection flow.

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Background: Whole brain radiotherapy is the treatment of choice for patients with brain metastases. However, neurocognitive functions decline due to impaired hippocampal neurogenesis might occur thereafter. It is hypothesized that conformal hippocampal avoidance during the course of WBRT might provide meaningful neurocognitive functions preservation. Our study aims to demonstrate the impact of delivering HA‑WBRT on NCF changes in patients receiving WBRT. Methods: fifty patients who were referred for cranial irradiation were enrolled in the study. Before the HA‑WBRT course and randomly assigned to two equal groups, the first group will receive conventional whole brain palliative radiotherapy and the second group will receive hippocampal sparing whole brain radiotherapy, assigned to 30 Gy over 10 fractions over two weeks, all participants should receive baseline neurocognitive assessment, including memory, executive functions, and psychomotor speed,the primary endpoint was delayed recall, as determined by the change/decline in Hopkins Verbal Learning Test (HVLT-R) and The One Card Learning Test (OCLT) from the baseline assessment to 4 months after the start of HA‑WBRT. Results: Regarding neurocognitive outcomes, no statistically significant differences were found between various NCF scores obtained at baseline and at post‑radiotherapy intervals, in immediate verbal memory and non‑verbal memory, except for delayed recall memory on HVLT-R Hopkins Verbal Learning Test -Revised for delayed recall Learning, p =0.008. Conclusions: Functional preservation by hippocampal sparing during WBRT could largely be achieved in this study, which also suggests that HA‑WBRT should be a feasible technique preserving neurocognitive functions while maintaining intracranial control.

SUMMARYThis experiment was carried out in a newly reclaimed desert area south-west of Alexandria. The purpose was to study the effect of breeding Barki ewes more than once per year on body weights and mortality rates of their lambs. Lambs were weighed 24 h after birth and at the ages of 1, 2, 2·5 (weaning age), 3, 4, 5, 6, 9 and 12 months.The experiment comprised three groups of single-born lambs of both sexes. The first group included 385 lambs born (in October–November) to ewes lambing once per year; tho second group comprised 155 lambs born (in January–February) to ewes lambing twice in twelve months and the third comprised 102 lambs also born in January–February to ewes lambing thrice in two consecutive years.Lambs born to ewes lambing once were heavier from the age of 1 month to the age of 5 months than lambs born to ewes lambing twice in the same year or three times in two consecutive years. However, the three groups of lambs did not significantly differ in their body weights from 5 to 12 months of age.Rebreedi ng did not significantly affect the mortality rate of lambs at the three studied ago periods, i.e. from birth to 1 month of age, from 1 month to weaning and from weaning to the age of 12 months.Sex had a significant effect on body weights of lambs but did not affect their mortality rates.

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