Measurement of the Spin Tune Using the Coherent Spin Motion of Polarized Protons in a Storage Ring.

This Letter reports the first spin tune measurement at high energies (24 and 255 GeV) with a driven coherent spin motion. To maintain polarization in a polarized proton collider, it is important to know the spin tune of the polarized proton beam, which is defined as the number of full spin precessions per revolution. A nine-magnet spin flipper has demonstrated high spin-flip efficiency in the presence of two Siberian snakes [H. Huang et al., Phys. Rev. Lett. 120, 264804 (2018).10.1103/PhysRevLett.120.264804]. The spin flipper drives a spin resonance with a given frequency (or tune) and strength. When the drive tune is close to the spin tune, the proton spin direction is not vertical anymore, but precesses around the vertical direction. By measuring the precession frequency of the horizontal component, the spin tune can be precisely measured. A driven coherent spin motion and fast turn-by-turn polarization measurement are keys to the measurement. The vertical spin direction is restored after turning the spin flipper off and the polarization value is not affected by the measurement. The fact that this manipulation preserves the polarization makes it possible to measure the spin tune during the operation of a high energy accelerator.

Infectious bursal disease virus suppresses H9N2 avian influenza viral shedding in broiler chickens.

1. Infectious bursal disease virus (IBDV) causes immunosuppression in chickens, increasing their susceptibility to other infectious diseases and resulting in vaccination failure. Here, we investigated the immune-depressing effect of IBDV on H9N2 avian influenza viral infection in the broiler chickens. 2. For this purpose, chickens were divided into four groups. In group A, chickens were inoculated with IBDV at 21 days of age and H9N2 avian influenza virus (AIV) 5 days later. Groups B and C only received AIV at 26 days of age and IBDV at 21 days, respectively. The control group (D) were inoculated with normal saline at the same times. Tissue samples from different organs were collected on the days 1, 3, 6, 9, and 12 after H9N2 infection. 3. Macroscopic observation showed IBD lesions in groups A and C, including swollen bursa with the presence of gelatinous exudates, haemorrhages in the thigh muscle, edema, and nephritis. 4. Reverse Transcription-PCR was used to study H9N2 AIV dissemination, and qRT-PCR to determine viral genome copy number in different organs. A considerable titre of AIV was found in the trachea, lungs, cecal tonsils, spleens, and feces of infected chickens. The genome copy number of the virus in the trachea and lungs of group A was significantly higher than that in group B on the first day after inoculation. But in the other days post inoculation, RT-PCR did not detect the AIV genome in group A. Although there might have been some immunosuppression in group A, IBDV could interfere with AIV replication in the chickens of this group. 5. In conclusion, we propose that pre-exposure to IBDV at 3 weeks of age reduces the replication and shedding of H9N2 in broiler chicken.

High Spin-Flip Efficiency at 255 GeV for Polarized Protons in a Ring With Two Full Siberian Snakes.

In polarized proton collision experiments, it is highly advantageous to flip the spin of each bunch of protons during the stores to reduce the systematic errors. Experiments done at energies less than 2 GeV have demonstrated a spin-flip efficiency over 99%. At high energy colliders with Siberian snakes, a single magnet spin flipper does not work because of the large spin tune spread and the generation of multiple, overlapping resonances. A more sophisticated spin flipper, constructed of nine-dipole magnets, was used to flip the spin in the BNL Relativistic Heavy Ion Collider. A special optics choice was also used to make the spin tune spread very small. A 97% spin-flip efficiency was measured at both 24 and 255 GeV. These results show that efficient spin flipping can be achieved at high energies using a nine-magnet spin flipper.

The HIV/AIDS caregiver identity as a double-edged sword: a discourse analysis on HIV/AIDS caregiving in South Africa

This article discusses the identity of HIV/AIDS caregivers as constructed by a group of HIV/AIDS caregivers at a non-profit organisation in South Africa. During a 12-month period data were collected through interviews with the organisation's staff and volunteers. Using discourse analysis; the study identified a caregiver identity constructed by participants. This caregiving identity acts as a double-edged sword: while the rewards of caregiving act as a buffer against stressful experiences; the prescriptive nature of the caregiver identity is taxing; and may explain burnout among HIV/AIDS caregivers. The study concludes that for support systems for HIV/AIDS caregivers to be effective; the social culture and identity of HIV/AIDS caregivers must be considered

Betaine: a promising antioxidant agent for enhancement of broiler meat quality.

1. Antioxidant and methyl donor effects of betaine in experimental animal models have recently been demonstrated. The present study was therefore designed to examine the antioxidant effects of betaine on the antioxidant status and meat quality of breast muscles in broilers. 2. Cobb broilers were randomly divided into Control, Methionine low, Methionine low plus betaine, and Betaine groups. 3. The activity of the main antioxidant enzyme (glutathione peroxidase) in the Betaine and the Methionine low plus betaine groups significantly increased compared to the Methionine low and Control groups. Catalase and superoxide dismutase activities were significantly higher in the Betaine group compared to the Methionine low group, and lipid peroxidation was significantly higher in the Control and the Methionine low groups. 4. The present study indicates that adding betaine (1 g/kg) to a diet deficient in methionine can significantly improve antioxidant defences and meat quality, decreasing lipid peroxidation in the breast muscles of broiler chickens.

Observation of higher-order snake resonances in polarized proton acceleration in RHIC.

Higher-order and coupled snake resonances were observed during the 2002 polarized proton run in RHIC. Strong depolarization was observed when the fractional part of the vertical betatron tune approached 1/4, and when the fractional part of the horizontal tune approached 3/14. Because of the closed orbit error, each snake resonance splits into two. From the width of the observed snake resonances, we can derive the strength of the imperfection spin resonance. Our results appear consistent with the measured closed orbit error.