Measurements in low-speed flow of unsteady pressure distributions on a rectangular wing with an oscillation control surface

The report describes an experiment made jointly by an Anglo-French team to determine unsteady pressure distributions and forces on a low aspect ratio wing with an oscillating control surface. Two series of tests were made in the R.A.E. 5 ft low-speed wind tunnel at frequency parameters between 0.73 and 8.45. The pressure-measuring installations were of two types ; one consisted of a number of individual transducers, and the other employed a series of tubes connected to a single transducer via a pressure switch. The results were compared with calculations based on methods developed at R.A.E. and O.N.E.R.A. The tests showed that the measuring systems provided results which were in themselves consistent; there were, however, disparities between upper and lower surface oscillatory pressure distributions which made comparisons between theory and experiment difficult

On staying grounded and avoiding Quixotic dead ends

The 15 articles in this special issue on The Representation of Concepts illustrate the rich variety of theoretical positions and supporting research that characterize the area. Although much agreement exists among contributors, much disagreement exists as well, especially about the roles of grounding and abstraction in conceptual processing. I first review theoretical approaches raised in these articles that I believe are Quixotic dead ends, namely, approaches that are principled and inspired but likely to fail. In the process, I review various theories of amodal symbols, their distortions of grounded theories, and fallacies in the evidence used to support them. Incorporating further contributions across articles, I then sketch a theoretical approach that I believe is likely to be successful, which includes grounding, abstraction, flexibility, explaining classic conceptual phenomena, and making contact with real-world situations. This account further proposes that (1) a key element of grounding is neural reuse, (2) abstraction takes the forms of multimodal compression, distilled abstraction, and distributed linguistic representation (but not amodal symbols), and (3) flexible context-dependent representations are a hallmark of conceptual processing

The effect of steady tailplane lift on the oscillatory behaviour of a T-tail flutter model at high subsonic speeds

The oscillatory behaviour of a T-tail has been investigated at high subsonic Mach numbers on an aeroelastic model having tailplane settings of zero and three degrees. There is broadly satisfactory agreement between calculated and measured values of modal frequency and damping. The comparison has been based mainly on the flutter margin criterion of Zimmerman and Weissenburger, since the more conventional comparisons are inconclusive

The overlooked significance of plasma volume for successful adaptation to high altitude in Sherpa and Andean natives

In contrast to Andean natives, high altitude Tibetans present with a lower hemoglobin concentration that correlates with reproductive success and exercise capacity. Decades of physiological and genomic research have assumed that the lower hemoglobin concentration in Himalayan natives results from a blunted erythropoietic response to hypoxia (i.e. no increase in total hemoglobin mass). In contrast, herein we test the hypothesis that the lower hemoglobin concentration is the result of greater plasma volume, rather than an absence of increased hemoglobin production. We assessed hemoglobin mass, plasma volume and blood volume in lowlanders at sea level, lowlanders acclimatized to high altitude, Himalayan Sherpa and Andean Quechua, and explored the functional relevance of volumetric hematological measures to exercise capacity. Hemoglobin mass was highest in Andeans, but also elevated in Sherpa compared to lowlanders. Sherpa demonstrated a larger plasma volume than Andeans, resulting in a comparable total blood volume at a lower hemoglobin concentration. Hemoglobin mass was positively related to exercise capacity in lowlanders at sea level and Sherpa at high altitude, but not in Andean natives. Collectively, our findings demonstrate a unique adaptation in Sherpa that reorientates attention away from hemoglobin concentration and towards a paradigm where hemoglobin mass and plasma volume may represent phenotypes with adaptive significance at high altitude

Control of human adenovirus type 5 gene expression by cellular Daxx/ATRX chromatin-associated complexes

Death domain–associated protein (Daxx) cooperates with X-linked α-thalassaemia retardation syndrome protein (ATRX), a putative member of the sucrose non-fermentable 2 family of ATP-dependent chromatin-remodelling proteins, acting as the core ATPase subunit in this complex, whereas Daxx is the targeting factor, leading to histone deacetylase recruitment, H3.3 deposition and transcriptional repression of cellular promoters. Despite recent findings on the fundamental importance of chromatin modification in host-cell gene regulation, it remains unclear whether adenovirus type 5 (Ad5) transcription is regulated by cellular chromatin remodelling to allow efficient virus gene expression. Here, we focus on the repressive role of the Daxx/ATRX complex during Ad5 replication, which depends on intact protein–protein interaction, as negative regulation could be relieved with a Daxx mutant that is unable to interact with ATRX. To ensure efficient viral replication, Ad5 E1B-55K protein inhibits Daxx and targets ATRX for proteasomal degradation in cooperation with early region 4 open reading frame protein 6 and cellular components of a cullin-dependent E3-ubiquitin ligase. Our studies illustrate the importance and diversity of viral factors antagonizing Daxx/ATRX-mediated repression of viral gene expression and shed new light on the modulation of cellular chromatin remodelling factors by Ad5. We show for the first time that cellular Daxx/ATRX chromatin remodelling complexes play essential roles in Ad gene expression and illustrate the importance of early viral proteins to counteract cellular chromatin remodelling

The effect of steady tailplane lift on the subcritical response of a subsonic T-tail flutter model

An aeroelastic model of an aircraft T-tail has been tested in a low speed wind tunnel. The purpose of the programme was firstly to check the validity of a method for calculating the aerodynamic forces acting on a T-tail oscillating about zero mean incidence. The secondary purpose was to measure the effect of tailplane incidence on aeroelastic behaviour, and to develop a method of calculation to take account of steady lift on the tailplane in the evaluation of flutter and sub-critical response. The Report presents the results of the tests and of the calculations, and shows that theory and experiment are in broad agreement, although accurate experimental data become difficult to obtain under certain conditions