Acoustics of rubbing feathers: the velvet of owl feathers reduces frictional noise.

One feather structure associated with an owl's ability to fly quietly is the soft dorsal surface on their flight feathers: the velvet. This velvet is a mat of elongated filamentous pennulums that extend up from feather barbules. The aerodynamic noise hypothesis posits this velvet reduces aerodynamic noise caused by formation of turbulence, while the structural noise hypothesis posits the velvet acts as a dry lubricant, reducing frictional noise produced by feathers sliding past one another.

Novel Autotaxin Inhibitor ATX-1d Significantly Enhances Potency of Paclitaxel-An In Silico and In Vitro Study.

The development of drug resistance in cancer cells poses a significant challenge for treatment, with nearly 90% of cancer-related deaths attributed to it. Over 50% of ovarian cancer patients and 30-40% of breast cancer patients exhibit resistance to therapies such as Taxol. Previous literature has shown that cytotoxic cancer therapies and ionizing radiation damage tumors, prompting cancer cells to exploit the autotaxin (ATX)-lysophosphatidic acid (LPA)-lysophosphatidic acid receptor (LPAR) signaling axis to enhance survival pathways, thus reducing treatment efficacy.

Sampling affects population genetic inference: A case study of the Allen's (Selasphorus sasin) and rufous hummingbird (Selasphorus rufus).

Gene flow can affect evolutionary inference when species are undersampled. Here, we evaluate the effects of gene flow and geographic sampling on demographic inference of 2 hummingbirds that hybridize, Allen's hummingbird (Selasphorus sasin) and rufous hummingbird (Selasphorus rufus). Using whole-genome data and extensive geographic sampling, we find widespread connectivity, with introgression far beyond the Allen's × rufous hybrid zone, although the Z chromosome resists introgression beyond the hybrid zone.

The Inverse Krogh Principle: All Organisms Are Worthy of Study.

AbstractKrogh's principle states, "For such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied." The downside of picking a question first and then finding an ideal organism on which to study it is that it will inevitably leave many organisms neglected. Here, we promote the inverse Krogh principle: all organisms are worthy of study.

Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage.

How do Great Gray Owls () capture voles (Cricetidae) through a layer of snow? As snow is a visual barrier, the owls locate voles by ear alone. To test how snow absorbs and refracts vole sound, we inserted a loudspeaker under the snowpack and analysed sound from the loudspeaker, first buried, then unburied. Snow attenuation coefficients rose with frequency (0.

Oh, snap! A within-wing sonation in black-tailed trainbearers.

Vertebrates communicate through a wide variety of sounds, but few mechanisms of sound production, besides vocalization, are well understood. During high-speed dives, male trainbearer hummingbirds (Lesbia spp.) produce a repeated series of loud snaps.

Ways that Animal Wings Produce Sound.

There are at least eight ways that wings potentially produce sound. Five mechanisms are aerodynamic sounds, created by airflow, and three are structural sound created by interactions of solid surfaces. Animal flight is low Mach (M), meaning all animals move at <30% of the speed of sound.

The population genetics of nonmigratory Allen's Hummingbird () following a recent mainland colonization.

Allen's Hummingbird comprises two subspecies, one migratory () and one nonmigratory (). The nonmigratory subspecies, previously endemic to the California Channel Islands, apparently colonized the California mainland on the Palos Verdes Peninsula some time before 1970 and now breeds throughout coastal southern California. We sequenced and compared populations of mainland nonmigratory Allen's Hummingbird to Channel Island populations from Santa Catalina, San Clemente, and Santa Cruz Island.

Introduction to the Symposium: Bio-Inspiration of Quiet Flight of Owls and Other Flying Animals: Recent Advances and Unanswered Questions.

Animal wings produce an acoustic signature in flight. Many owls are able to suppress this noise to fly quietly relative to other birds. Instead of silent flight, certain birds have conversely evolved to produce extra sound with their wings for communication.

Mindfulness-Based Stress Reduction in the Management of Chronic Pain and Its Comorbid Depression.

Context: Chronic pain (CP) is a common and serious medical condition, with an estimated 100 million people affected in the United States. In the 1990s, opioids were increasingly prescribed to manage chronic pain, and this practice contributed to the opioid epidemic of the 21st century. To combat this epidemic, multidisciplinary approaches to chronic pain management are being researched and implemented.

Humming hummingbirds, insect flight tones and a model of animal flight sound.

Why do hummingbirds hum and insects whine when their wings flap in flight? Gutin proposed that a spinning propeller produces tonal sound because the location of the center of aerodynamic pressure on each blade oscillates relative to an external receiver. Animal wings also move, and in addition, aerodynamic force produced by animal wings fluctuates in magnitude and direction over the course of the wingbeat. Here, we modeled animal wing tone as the equal, opposite reaction to aerodynamic forces on the wing, using Lowson's equation for the sound field produced by a moving point force.

Mindfulness-Based Stress Reduction in the Management of Chronic Pain and Its Comorbid Depression.

Context: Chronic pain (CP) is a common and serious medical condition, with an estimated 100 million people affected in the United States. In the 1990s, opioids were increasingly prescribed to manage chronic pain, and this practice contributed to the opioid epidemic of the 21st century. To combat this epidemic, multidisciplinary approaches to chronic pain management are being researched and implemented.

Sonations in Migratory and Non-migratory Fork-tailed Flycatchers (Tyrannus savana).

Sonations are sounds that animals produce with structures other than the vocal apparatus for communication. In birds, many sonations are usually produced with modified flight feathers through diverse kinematic mechanisms. For instance, aeroelastic fluttering of feathers produces tonal sound when airflow exceeds a threshold velocity and induces flight feathers to oscillate at a constant frequency.

Evidence that the Dorsal Velvet of Barn Owl Wing Feathers Decreases Rubbing Sounds during Flapping Flight.

Owls have specialized feather features hypothesized to reduce sound produced during flight. One of these features is the velvet, a structure composed of elongated filaments termed pennulae that project dorsally from the upper surface of wing and tail feathers. There are two hypotheses of how the velvet functions to reduce sound.

Specialized Feathers Produce Sonations During Flight in Columbina Ground Doves.

The shape of remiges (primary and secondary feathers) is constrained and stereotyped by the demands of flight, but members of the subfamily of New World ground doves (Peristerinae) possess many atypical remex shapes with which they produce sonations of alarm. Within the genus Columbina specifically, the seventh primary feathers (P7) have elongated barbs that create a protrusion on the trailing vane which varies in size and shape between species. These feathers are hypothesized to have been coopted to produce communicative sounds (i.

Evolutionary and Ecological Correlates of Quiet Flight in Nightbirds, Hawks, Falcons, and Owls.

Two hypotheses have been proposed for the evolution of structures that reduce flight sounds in birds. According to the stealth hypothesis, flying quietly reduces the ability of other animals (e.g.

Evolution and Ecology of Silent Flight in Owls and Other Flying Vertebrates.

We raise and explore possible answers to three questions about the evolution and ecology of silent flight of owls: (1) do owls fly silently for stealth, or is it to reduce self-masking? Current evidence slightly favors the self-masking hypothesis, but this question remains unsettled. (2) Two of the derived wing features that apparently evolved to suppress flight sound are the vane fringes and dorsal velvet of owl wing feathers. Do these two features suppress aerodynamic noise (sounds generated by airflow), or do they instead reduce structural noise, such as frictional sounds of feathers rubbing during flight? The aerodynamic noise hypothesis lacks empirical support.

Subtle, pervasive genetic correlation between the sexes in the evolution of dimorphic hummingbird tail ornaments.

Male hummingbirds have repeatedly evolved sexually dimorphic tails that they use as ornaments during courtship. We examine how male ornament evolution is reflected in female morphology. Lande's two-step model of the evolution of dimorphism predicts that γ (the genetic correlation between the sexes) causes trait elaboration to first evolve quickly in both sexes, then dimorphism evolves more slowly.

Effect of Intensive Glycemic Control on Risk of Lower Extremity Amputation.

Background: Diabetes mellitus is a major risk factor for peripheral arterial disease and lower extremity amputation (LEA). We evaluated the effects of intensive glucose control (IGC) on risk of LEA in patients with type 2 diabetes during a randomized-controlled multicenter trial.

Study Design: The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial randomized patients with type 2 diabetes to IGC (HbA1c target < 6.

Kinematic control of male Allen's hummingbird wing trill over a range of flight speeds.

Wing trills are pulsed sounds produced by modified wing feathers at one or more specific points in time during a wingbeat. Male Allen's hummingbirds () produce a sexually dimorphic 9 kHz wing trill in flight. Here, we investigated the kinematic basis for trill production.

Quantification of free sugars, fructan, pungency and sweetness indices in onion populations by FT-MIR spectroscopy.

Background: To facilitate faster phenotyping of onions (Allium cepa L.), Fourier-transform mid infrared (FT-MIR) spectroscopy with partial least squares (PLS) regression modelling was evaluated for the determination of pungency (pyruvate), sweetness (free sugars) and fructan in juice samples (n = 605) expressed from bulbs from breeding populations.

Results: Fourier-transform infrared (FTIR) spectra (range 1700-900 cm ) were obtained from droplets (30 μL) of unprocessed juice.

Strategic Acoustic Control of a Hummingbird Courtship Dive.

Male hummingbirds court females with a high-speed dive in which they "sing" with their tail feathers. The male's choice of trajectory provides him strategic control over acoustic frequency and pressure levels heard by the female. Unlike related species, male Costa's hummingbirds (Calypte costae) choose to place their dives to the side of females.

Complex coevolution of wing, tail, and vocal sounds of courting male bee hummingbirds.

Phenotypic characters with a complex physical basis may have a correspondingly complex evolutionary history. Males in the "bee" hummingbird clade court females with sound from tail-feathers, which flutter during display dives. On a phylogeny of 35 species, flutter sound frequency evolves as a gradual, continuous character on most branches.

Resonance frequencies of honeybee () wings.

During flight, insect wings bend and twist under the influence of aerodynamic and inertial forces. We tested whether wing resonance of honeybees () matches the wingbeat frequency, against the 'stiff element' hypothesis that the wing's first longitudinal mode exceeds the wingbeat frequency. Six bees were immobilized with their right wing pair outspread, and stimulated with a shaker while the normal modes were recorded with a scanning Doppler laser vibrometer.