A preliminary comparison between the SR-6 propeller noise in flight and in a wind tunnel

High speed turboprops offer an attractive candidate for aircraft because of their high propulsive efficiency. However, one of the possible problems associated with these propellers is their high noise level at cruise condition that may create a cabin environment problem. Models of these propellers were tested for acoustics in the 8 by 6-foot wind tunnel and on the Jet Star airplane. Comparisons between the airplane and wind tunnel data for the SR-6 propeller are shown. The comparison of maximum blade passing tone variation with helical tip Mach number between the tunnel and flight data was good when corrected to the same test conditions. Directivity comparisons also showed fairly good agreement. These good comparisons indicate that the wind tunnel is a viable location for measuring the blade passage tone noise of these propellers

Interferon Beta 2/Interleukin-6 and Interleukin-3 Synergize in Stimulating Proliferation of Human Early Hematopoietic Progenitor Cells.

Early 4-hydroxyperoxycyclophosphamide (4-HC) resistant hematopoietic progenitor cells (pre-colony-forming units, pre-CFU) were evaluated by a two-step liquid culture system, (earlier progenitors), pre-CFU, as well as by the conventional semi-solid mixed colony assay (later progenitors) for their growth response to interleukin-6 (IL-6), interleukin-3 (IL-3), and a combination of both factors. The effect of the IL-6/IL-3 combination was compared to that of IL-1/IL-3. IL-3 alone proved less effective in supporting earlier pre-CFU cells than later progenitor cells. In a previous work IL-6 promoted the growth of early multipotential progenitor cells circulating in hairy cell leukemia (HCL) patients. IL-6 alone did not stimulate growth of either early or later normal progenitor cells. However, a significant synergistic effect was obtained when IL-6 and IL-3 were added together (p \u3c0.05). IL-6/IL-3 synergism was more potent than IL-1/IL-3 in promoting growth of colonies. The previously described synergistic effect of IL-1/IL-3 seems to be independent of IL-6. Thus, our results suggest that the multifunctional cytokine IL-6, may be of use in shortening the engraftment time in bone marrow transplantation

Study of the Λp\Lambda p Interaction Close to the Σ+n\Sigma^+n and Σ0p\Sigma^0p Thresholds

The $\Lambda p$ interaction close to the $\Sigma N$ threshold is considered. Specifically, the pronounced structure seen in production reactions like $K^-d \to \pi^- \Lambda p$ and $pp\to K^+ \Lambda p$ around the $\Sigma N$ threshold is analyzed. Modern interaction models of the coupled $\Lambda N - \Sigma N$ systems generate such a structure either due to the presence of a (deuteron-like) unstable bound state or of an inelastic virtual state. % A determination of the position of the prominent peak as observed in various experiments for the two aforementioned reactions leads to values that agree quite well with each other. Furthermore, the deduced mean value of $2128.7\pm 0.3$ MeV for the peak position coincides practically with the threshold energy of the $\Sigma^+ n$ channel. This supports the interpretation of the structure as a genuine cusp, signaling an inelastic virtual state in the $^3S_1-^3D_1$ partial wave of the $\Sigma N$ isospin 1/2 channel. % There is also evidence for a second peak (or shoulder) in the data sets considered which appears at roughly 10-15 MeV above the $\Sigma N$ threshold. However, its concrete position varies significantly from data set to data set and, thus, a theoretical interpretation is difficult.Comment: accepted for publication Nucl. Phys.

Slaughterhouse blood as a perfusate for studying myocardial function under ischemic conditions

Abstract Metabolic studies using the in vitro non-recirculating blood-perfused isolated heart model require large volumes of blood. The present study was designed to determine whether heterologous pig blood collected from a slaughterhouse can be used as perfusate for isolated pig hearts perfused under aerobic and constant reduced flow conditions. Eight isolated working pig hearts perfused for 90 min at a constant flow of 1.5 ml g -1 min -1 with non-recirculated blood diluted with KrebsHenseleit bicarbonate buffer at a hematocrit of 23% were compared to eight hearts subjected to the same protocol but perfused only with Krebs-Henseleit bicarbonate buffer solution. Hearts were paced at 100 bpm and subjected to aerobic perfusion at 38ºC. Hearts were weighed before perfusion and at the end of the experiment and the results are reported as percent weight gain (mean ± SD). Comparisons between groups were performed by the Student t-test (P<0.05). After 90 min of perfusion with modified Krebs-Henseleit, perfused hearts presented a larger weight gain than blood-perfused hearts (39.34 ± 9.27 vs 23.13 ± 5.42%, P = 0.003). Left ventricular end-diastolic pressure was higher in the modified Krebs-Henseleit-perfused group than in the blood group (2.8 ± 0.4 vs 2.3 ± 0.3 mmHg, respectively, P = 0.01). We conclude that heterologous blood perfusion, by preserving a more physiological myocardial water content, is a better perfusion fluid than modified Krebs-Henseleit solution for quantitative studies of myocardial metabolism and heart function under ischemic conditions

A Rare Form of Silene acaulis L. (moss Campion) from British Columbia

While conducting an Ecological Reserves survey of Morfee Mountain in North Central British Columbia (55° 26' N, 123° 04' W) during mid-July 1971, the author noted an interesting variation of flower colour in Silene acaulis L. subsp. subacaulescens (F.N. Williams) Hult. The flower colours of Silene acaulis are usually purple, pink or lavender throughout its range. The majority of the individuals of this species on Morfee Mountain conformed to the usual flower colour. However, one individual plant with pure white petals was observed .... The specimen was collected near the British Columbia Telephone Company microwave relay station on Morfee Mountain at an elevation of about 1700 m. ... Although the white-flowered form of Silene acaulis is not unknown, Hultén (1968) notes that this form is rare, thus making the find an interesting observation for both the amateur botanist and the more serious student of intraspecific variation in plants

Northern Canadian Gardening: Compost Piles as a Means of Extending the Growing Range of Northern Crops

... The use of compost piles for growing frost-sensitive crops with long growing seasons holds considerable promise as a technique for northern domestic gardening, incorporating the benefits of direct garden seeding with those of conventional hot beds. The owners of most of the 50 gardens examined in Dawson in 1980 (McCracken and Revel, 1982) composted organic wastes, though none of them used compost piles for crop production. The abundance of compost piles and the successful growth of the volunteer cucumbers we observed suggests that this technique could be widely used throughout the north by those who wish to grow warmer-climate crops without a greenhouse, and without the need for bedding-out plants

Effects of Neck Muscle Fatigue on the Vestibulo-Ocular Reflex

In order to maintain balance, the brain receives and processes input from multiple sensory systems including the visual, vestibular, and somatosensory systems. The information from these systems is sent to the brain where the information is then combined, organized and interpreted. This results in the output of reflexes (vestibulo-ocular reflex [VOR] and vestibulospinal reflex [VSR]). The VOR and the VSR work together with other motor systems to control gaze stability and control whole body equilibrium. Impairment in any of these sensory systems can result in dizziness, loss of balance, and visual instability. While the contributions of the visual, vestibular, and somatosensory systems on visual stability have been well described in the literature, contribution of cervical spine somatosensation on visual stability is not fully understood. The overall aim of the present work was to investigate whether impaired somatosensory information from the cervical spine, caused by neck muscle fatigue, directly influences dynamic visual stability in healthy young and healthy older participants. Results indicated that healthy young and healthy older participants who were fatigued had significantly poorer Dynamic Visual Acuity (DVA) than those who were not fatigued (P\u3c.05). In Conclusion, our research suggests that when assessing vestibular function in patients complaining of dizziness and/or visual disturbance with a history of neck trauma, one may speculate that VOR dysfunction could have a cervical origin due to somatosenory disturbance, which may lead to visual disturbances and dizziness