Effect of Changing the Vocal Tract Shape on the Sound Production of the Recorder: An Experimental and Theoretical Study

Changing the vocal tract shape is one of the techniques which can be used by the players of wind instruments to modify the quality of the sound. It has been intensely studied in the case of reed instruments but has received only little attention in the case of air-jet instruments. This paper presents a first study focused on changes in the vocal tract shape in recorder playing techniques. Measurements carried out with recorder players allow to identify techniques involving changes of the mouth shape as well as consequences on the sound. A second experiment performed in laboratory mimics the coupling with the vocal tract on an artificial mouth. The phase of the transfer function between the instrument and the mouth of the player is identified to be the relevant parameter of the coupling. It is shown to have consequences on the spectral content in terms of energy distribution among the even and odd harmonics, as well as on the stability of the first two oscillating regimes. The results gathered from the two experiments allow to develop a simplified model of sound production including the effect of changing the vocal tract shape. It is based on the modification of the jet instabilities due to the pulsating emerging jet. Two kinds of instabilities, symmetric and anti-symmetric, with respect to the stream axis, are controlled by the coupling with the vocal tract and the acoustic oscillation within the pipe, respectively. The symmetry properties of the flow are mapped on the temporal formulation of the source term, predicting a change in the even / odd harmonics energy distribution. The predictions are in qualitative agreement with the experimental observations

Can virtual nature improve patient experiences and memories of dental treatment? A study protocol for a randomized controlled trial

Background Dental anxiety and anxiety-related avoidance of dental care create significant problems for patients and the dental profession. Distraction interventions are used in daily medical practice to help patients cope with unpleasant procedures. There is evidence that exposure to natural scenery is beneficial for patients and that the use of virtual reality (VR) distraction is more effective than other distraction interventions, such as watching television. The main aim of this randomized controlled trial is to determine whether the use of VR during dental treatment can improve the overall dental experience and recollections of treatment for patients, breaking the negative cycle of memories of anxiety leading to further anxiety, and avoidance of future dental appointments. Additionally, the aim is to test whether VR benefits dental patients with all levels of dental anxiety or whether it could be especially beneficial for patients suffering from higher levels of dental anxiety. The third aim is to test whether the content of the VR distraction can make a difference for its effectiveness by comparing two types of virtual environments, a natural environment and an urban environment. Methods/design The effectiveness of VR distraction will be examined in patients 18 years or older who are scheduled to undergo dental treatment for fillings and/or extractions, with a maximum length of 30 minutes. Patients will be randomly allocated into one of three groups. The first group will be exposed to a VR of a natural environment. The second group will be exposed to a VR of an urban environment. A third group consists of patients who receive standard care (control group). Primary outcomes relate to patients’ memories of the dental treatment one week after treatment: (a) remembered pain, (b) intrusive thoughts and (c) vividness of memories. Other measures of interest are the dental experience, the treatment experience and the VR experience. Trial registration Current Controlled Trials ISRCTN4144280

Revision of the age of magnetization of the Montmartin red beds, Normandy, France

A new roadcut has enabled us to sample the south-dipping limb of the Montmartin syncline for a palaeomagnetic reevaluation of an earlier result published by Jones, Van der Voo & Bonhommet. In combination with the results previously published in 1979 for the north-dipping beds of the syncline, a conclusively negative fold test is obtained. The resulting magnetization (declination/inclination =206°/-3°, Α 95 = 12°, palaeopole at 38°S, 325°E) is interpreted to be of Late Carboniferous age, not Late Devonian as thought earlier. Simultaneously, we have re-evaluated the age of the rocks, previously thought to be Late Devonian on the basis of Acritarchs, Chitinozoans and spores. It has not been possible to reconfirm these fossils, not even in the same samples as studied originally; in contrast, the regional presence of Early Palaeozoic fossils suggests to us an age similar to that of other red beds in the Arrnorican Massif, which have been dated as Early Ordovician. The geodynamic implications of our finding that the Montmartin rocks are completely remagnetized, however, are of no great consequence for the geodynamics of the Hercynian belt. Pre-folding magnetization obtained from Silurian and Devonian rocks in Spain and Germany argue for the same conclusion as reached erroneously in our earlier study, namely that the Armorican Massif and adjacent parts of Hercynian Europe were adjointed to North America, Great Britain, the Baltic Shield and the Russian Platform since at least Late Devonian time. If a Medio-European ocean existed during the Palaeozoic, it was virtually closed before the mid-Devonian and of insignificant width during Culm deposition in Early Carboniferoirs time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74719/1/j.1365-246X.1985.tb05108.x.pd

Membranes in rod solutions: a system with spontaneously broken symmetry

We consider a dilute solution of infinitely rigid rods near a curved, perfectly repulsive surface and study the contribution of the rod depletion layer to the bending elastic constants of membranes. We find that a spontaneous curvature state can be induced by exposure of BOTH sides of the membrane to a rod solution. A similar result applies for rigid disks with a diameter equal to the rod's length. We also study the confinement of rods in spherical and cylindrical repulsive shells. This helps elucidate a recent discussion on curvature effects in confined quantum mechanical and polymer systems.Comment: 10 pages, 2 figures, 1 table; submitted to PR

SNiP and cut: Quantifying the potential benefits of genomic selection tools for genetic fault elimination in sheep

ABSTRACT Whole genome single nucleotide polymorphism marker (SNP) technologies are rapidly being developed and could well play a role in the future selection of farmed animals. In sheep, work is being carried out to identify SNP's associated with economically important production traits and disease resistance. Stud sheep breeders routinely cull up to 30% of lambs born due to a variety of faults. Despite this culling pressure, the faults keep occurring, suggesting low heritability, recessive inheritance or incomplete penetration of fault causing genes. The objective of this paper was to identify the potential of SNP fault detection and elimination in sheep. Simulation was used to predict changes in gene frequencies and in an index of genetic merit of production traits over time when between two and 30 SNPs were used to aid selection. The SNPs are assumed to predict the presence of deleterious recessive genes. As selection pressure applied to individual or combination SNPs increased, the rate of increase in production trait genetic merit slowed down. Thus, a balance would be required between the emphasis on SNPs actively used to select against genetic faults, relative to emphasis on genetic merit. This work identified scope for substantial economic benefits from application of SNP technology for removal of faults to both stud breeders and commercial sheep farmers

Somatosensory Loss Influences the Adoption of Self-Centered Versus Decentered Perspectives

The body and the self are commonly experienced as forming a unity. Experiencing the external world as distinct from the self and the body strongly relies on adopting a single self-centered perspective which results in integrating multisensory sensations into one egocentric body-centered reference frame. Body posture and somatosensory representations have been reported to influence perception and specifically the reference frame relative to which multisensory sensations are coded. In the study reported here, we investigated the role of somatosensory and visual information in adopting self-centered and decentered spatial perspectives. Two deafferented patients who have neither tactile nor proprioceptive perception below the head and a group of age-matched control participants performed a graphesthesia task, consisting of the recognition of ambiguous letters (b, d, p, and q) drawn tactilely on head surfaces. To answer which letter was drawn, the participants can adopt either a self-centered perspective or a decentered one (i.e., centered on a body part or on an external location). The participants’ responses can be used, in turn, to infer the way the left-right and top-bottom letters’ axes are assigned with respect to the left-right and top-bottom axes of their body. In order to evaluate the influence of body posture, the ambiguous letters were drawn on the participants’ forehead, left, and right surfaces of the head, with the head aligned or rotated in yaw relative to the trunk. In order to evaluate the role of external information, the participants completed the task with their eyes open in one session and closed in another one. The results obtained in control participants revealed that their preferred perspective varied with body posture but not with vision. Different results were obtained with the deafferented patients who overall do not show any significant effect of their body posture on their preferred perspective. This result suggests that the orientation of their self is not influenced by their physical body. There was an effect of vision for only one of the two patients. The deafferented patients rely on strategies that are more prone to interindividual differences, which highlights the crucial role of somatosensory information in adopting self-centered spatial perspectives

Field-effect transistors assembled from functionalized carbon nanotubes

We have fabricated field effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic properties of the nanotubes. The devices we have fabricated show excellent electrical characteristics.Comment: 5 pages, 6 figure

Polymer Flow Through Porous Media: Numerical Prediction of the Contribution of Slip to the Apparent Viscosity.

The flow of polymer solutions in porous media is often described using Darcy’s law with an apparent viscosity capturing the observed thinning or thickening effects. While the macroscale form is well accepted, the fundamentals of the pore-scale mechanisms, their link with the apparent viscosity, and their relative influence are still a matter of debate. Besides the complex effects associated with the rheology of the bulk fluid, the flow is also deeply influenced by the mechanisms occurring close to the solid/liquid interface, where polymer molecules can arrange and interact in a complex manner. In this paper, we focus on a repulsive mechanism, where polymer molecules are pushed away from the interface, yielding a so-called depletion layer in the vicinity of the wall. This depletion layer acts as a lubricating film that may be represented by an effective slip boundary condition. Here, our goal is to provide a simple mean to evaluate the contribution of this slip effect to the apparent viscosity. To do so, we solve the pore-scale flow numerically in idealized porous media with a slip length evaluated analytically in a tube. Besides its simplicity, the advantage of our approach is also that it captures relatively well the apparent viscosity obtained from core-flood experiments, using only a limited number of inputs. Therefore, it may be useful in many applications to rapidly estimate the influence of the depletion layer effect over the macroscale flow and its relative contribution compared to other phenomena, such as non-Newtonian effects