Empirical scaling of antisymmetric stratified wakes

Proceedings of the "Bluff Body Wakes and Vortex-Induced Vibrations - BBVIV-4"Initially turbulent wakes of a propelled cylinder at nonzero angles of yaw to the mean flow were measured in the horizontal centerplane plane up to approximately 100 buoyancy times, where vertical velocities are very small. The profiles of mean velocity were found to be antisymmetric throughout their lifetime, with both width and maximum velocity decaying at the same rate as previously studied momentum wakes. The maximum velocity of the profile is proportional to the angle of yaw, but the width is constant. Both the mean flow and fluctuating quantities show that the late wake is self-similar, with scaling laws that are consistent with previous work on propelled and drag wakes

Three-dimensional simulation for fast forward flight of a calliope hummingbird

We present a computational study of flapping-wing aerodynamics of a calliope hummingbird (Selasphorus calliope) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3 m s−1. The advance ratio, i.e. the ratio between flight speed and average wingtip speed, is around one. An immersed-boundary method was used to simulate flow around the wings and bird body. The result shows that both downstroke and upstroke in a wingbeat cycle produce significant thrust for the bird to overcome drag on the body, and such thrust production comes at price of negative lift induced during upstroke. This feature might be shared with bats, while being distinct from insects and other birds, including closely related swifts

Aerodynamics of the Hovering Hummingbird

Despite profound musculoskeletal differences, hummingbirds (Trochilidae) are widely thought to employ aerodynamic mechanisms similar to those used by insects. The kinematic symmetry of the hummingbird upstroke and downstroke has led to the assumption that these halves of the wingbeat cycle contribute equally to weight support during hovering, as exhibited by insects of similar size. This assumption has been applied, either explicitly or implicitly, in widely used aerodynamic models, and in a variety of empirical tests. Here we provide measurements of the wake of hovering rufous hummingbirds (Selasphorus rufus) obtained with digital particle image velocimetry that show force asymmetry: hummingbirds produce 75% of their weight support during the downstroke and only 25% during the upstroke. Some of this asymmetry is probably due to inversion of their cambered wings during upstroke. The wake of hummingbird wings also reveals evidence of leading-edge vortices created during the downstroke, indicating that they may operate at Reynolds numbers sufficiently low to exploit a key mechanism typical of insect hovering. Hummingbird hovering approaches that of insects, yet remains distinct because of effects resulting from an inherently dissimilar—avian—body plan

Wake Development behind Paired Wings with Tip and Root Trailing Vortices: Consequences for Animal Flight Force Estimates

Recent experiments on flapping flight in animals have shown that a variety of unrelated species shed a wake behind left and right wings consisting of both tip and root vortices. Here we present an investigation using Particle Image Velocimetry (PIV) of the behaviour and interaction of trailing vortices shed by paired, fixed wings that simplify and mimic the wake of a flying animal with a non-lifting body. We measured flow velocities at five positions downstream of two adjacent NACA 0012 aerofoils and systematically varied aspect ratio, the gap between the wings (corresponding to the width of a non-lifting body), angle of attack, and the Reynolds number. The range of aspect ratios and Reynolds number where chosen to be relevant to natural fliers and swimmers, and insect flight in particular. We show that the wake behind the paired wings deformed as a consequence of the induced flow distribution such that the wingtip vortices convected downwards while the root vortices twist around each other. Vortex interaction and wake deformation became more pronounced further downstream of the wing, so the positioning of PIV measurement planes in experiments on flying animals has an important effect on subsequent force estimates due to rotating induced flow vectors. Wake deformation was most severe behind wings with lower aspect ratios and when the distance between the wings was small, suggesting that animals that match this description constitute high-risk groups in terms of measurement error. Our results, therefore, have significant implications for experimental design where wake measurements are used to estimate forces generated in animal flight. In particular, the downstream distance of the measurement plane should be minimised, notwithstanding the animal welfare constraints when measuring the wake behind flying animals

The distribution of dimethyl sulphide in some New Zealand wines

All New Zealand experimental wines of the vintages 1975-1980 tested showed the presence of DMS in at least one vintage year, whether the wines were red or white. There was a general trend for older wines to have a higher probability for the presence of DMS than younger wines. The variability in the presence of DMS was suggested to be related to the processing of the wines. Dimethyl sulphoxide seems to be the precursor of DMS formed during bottle aging.Carbonyl sulphide found in grape juices was thought to be lost during fermentation because of its high volatility.Über das Vorkommen von Dimethylsulfid in einigen neuseeländischen WeinenVon allen auf das Vorkommen von Dimethylsulfirl (DMS) untersuchten neuseeländischen weißen und roten Versuchsweinen der Jahrgänge 1975-1980 zeigte zumindest ein Jahrgang die Anwesenheit dieser Aromakomponente. Ältere Weine scheinen ganz allgemein häufiger DMS zu enthalten als junge. Es wird vermutet, daß die hohe Streubreite von der Weinbereitung abhängt. Dimethylsulfoxid scheint die Vorstufe von DMS zu sein, das während des Alterungsprozesses auf der Flasche entstehen könnte.In einigen Mosten wurde Carbonylsulfid nachgewiesen, das jedoch wegen seiner hohen Flüchtigkeit mit dem Gärgas entweichen dürfte

The resistivity of lanthanum, cerium, praseodymium and neodymium at low temperatures

The electrical resistivity of lanthanum, cerium, praseodymium, and neodymium was measured between room temperature and approximately 2°K. The behavior was found to be affected by the method of preparation, the heat treatment, and the crystal structure of the samples, the latter bearing the greatest significance

The heats of combustion of some rare-earth metals

A bomb calorimeter for measuring the heats of combustion of neodymium, samarium, gadolinium and erbium is described. The heats of combustion of these metals and the heats of formation of their oxides are reported

Atypical features in pleomorphic adenoma--a clinicopathologic study and implications for management.

Pleomorphic adenoma is the most common salivary gland neoplasm and infrequently undergoes malignant transformation. Carcinoma ex pleomorphic adenoma is typically an infiltrative neoplasm with features of cellular pleomorphism, high mitotic activity, peri-neural and vascular invasion. More recently, sub-groups of pleomorphic adenoma have been described exhibiting vascular invasion and features of malignancy without evidence of extra-capsular extension. There is little information in the literature regarding how these different histological variants influence clinical presentation and outcome following primary treatment. Following a review of 100 consecutive pleomorphic adenomas removed from the major salivary glands, 4 cases with atypical histological features were found. Three tumours exhibited features of dysplasia/carcinoma without evidence of extra-capsular invasion and a further case demonstrated benign vascular invasion. There were no clinical features suggestive of the atypical nature of these neoplasms, though fine needle aspiration cytology (FNAC) was suspicious of a malignancy in 2 cases and CT scan in 1 case. Patients underwent a superficial parotidectomy or submandibular gland excision based on the location of the lesion. All lesions were completely excised and there were no recurrences in this series

IUPHAR-DB: An Open-Access, Expert-Curated Resource for Receptor and Ion Channel Research

[Image: see text] This contribution highlights efforts by the International Union of Basic and Clinical Pharmacology (IUPHAR) Nomenclature Committee (NC-IUPHAR) to classify human receptors and ion channels, to document their properties, and to recommend ligands that are useful for characterization. This effort has inspired the creation of an online database (IUPHAR-DB), which is intended to provide free information to all scientists, summarized from primary literature by experts

Selective inhibition of extra-synaptic α5-GABA_A receptors by S44819, a new therapeutic agent

In the mammalian central nervous system (CNS) GABAA receptors (GABAARs) mediate neuronal inhibition and are important therapeutic targets. GABAARs are composed of 5 subunits, drawn from 19 proteins, underpinning expression of 20-30 GABAAR subtypes. In the CNS these isoforms are heterogeneously expressed and exhibit distinct physiological and pharmacological properties. We report the discovery of S44819, a novel tricyclic oxazolo-2,3-benzodiazepine-derivative, that selectively inhibits α5-subunit-containing GABAARs (α5-GABAARs). Current α5-GABAAR inhibitors bind to the “benzodiazepine site”. However, in HEK293 cells expressing recombinant α5-GABAARs, S44819 had no effect on 3H-flumazenil binding, but displaced the GABAAR agonist 3H-muscimol and competitively inhibited the GABA-induced responses. Importantly, we reveal that the α5-subunit selectivity is uniquely governed by amino acid residues within the α-subunit F-loop, a region associated with GABA binding. In mouse hippocampal CA1 neurons, S44819 enhanced long-term potentiation (LTP), blocked a tonic current mediated by extrasynaptic α5-GABAARs, but had no effect on synaptic GABAARs. In mouse thalamic neurons, S44819 had no effect on the tonic current mediated by δ-GABAARs, or on synaptic (α1β2γ2) GABAARs. In rats, S44819 enhanced object recognition memory and reversed scopolamine-induced impairment of working memory in the eight-arm radial maze. In conclusion, S44819 is a first in class compound that uniquely acts as a potent, competitive, selective antagonist of recombinant and native α5-GABAARs. Consequently, S44819 enhances hippocampal synaptic plasticity and exhibits pro-cognitive efficacy. Given this profile, S44819 may improve cognitive function in neurodegenerative disorders and facilitate post-stroke recovery