Mechanical properties of the vocal folds (such as stiffness or viscoelastic properties) play an essential role in phonation. They affect not only voice quality but also onset threshold of vocal fold self-excited oscillation, a sound source of voice [1]. Many experimental data on the mechanical properties have been reported so far, in which in vitro [2] or in vivo measurement techniques [3] were employed. In vitro measurements give us detailed information on the mechanical properties, yet it would be required to consider possible loss of freshness of the specimen. Meanwhile, current in vivo measurement methods utilize a thin probe to deform the vocal fold tissue located at the back of the throat and hence need technical skills for the surveyor to successfully obtain its loading-deformation relationship.

In the current study we apply the magnetic resonance elastography (MRE) technique to estimate the dynamic shear modulus of mouse brain tissue in vivo . The frequency used (1200 Hz) is well above those reported previously [1]. Estimates of dynamic shear modulus range from 12,600–14,800 N/m 2 at 1200 Hz. These data are strictly relevant only to small oscillations at this specific frequency, but these values are obtained at high frequencies (and thus high deformation rates) and non-invasively throughout the brain. These data complement measurements of nonlinear viscoelastic properties obtained by others at slower rates, either ex vivo or invasively.

The flow through a flexible tube and the interactions between fluid- and wall-motion have been researched in recent forty years because they are involved in many physiological phenomena, such as clinically useful “Korotkoff sounds”, audible murmurs induced by the collapsed external jugular vein in the neck of upright subject (Grotberg and Jenson, 2004).

This paper investigates the effect of superimposed length oscillation (SILO) on tidal breathing on contracted airway smooth muscle (ASM) relaxation. The combined effect of SILO with each one of four inhibitors (Isoproterenol, Indomethacin, PD0980590 and SB 203580) is investigated to explore the molecular pathways involved in the tissue relaxation process.

Current hemodialysis techniques rely on hollow-fiber tubes in a tube-and-shell operating approach. The method works satisfactorily; but, technological advantages of this method are already exhausted for a long time. Additional improvements are needed which could provide a way towards improving patient health and quality of life. Patients with renal failure undergo intense filtration sessions approximately three times a week leaving them fatigued. Large oscillations in concentration of various solutes within blood cause detrimental consequences on the overall health of patients.

We evaluated the acute (up to 24 hours) pathophysiological response to primary blast using a rat model and helium driven shock tube. The shock tube generates animal loadings with controlled pure primary blast parameters over a wide range of field-relevant conditions. The biomechanical loading was evaluated using a set of pressure gauges mounted on the surface of the nose, in the cranial space and in the thoracic cavity of cadaver rats. The mortality rates were established using anesthetized rats exposed to a single blast at five peak overpressures over a wide range of shock intensities (130, 190, 230, 250 and 290 kPa). We observed 0% mortality rates in 130 and 230 kPa groups, and 30%, 24% and 100% mortality rates in 190, 250 and 290 kPa groups, respectively. The intracranial pressure (ICP) oscillations recorded for 190, 250 and 290 kPa groups are characterized by higher frequency (10–20 kHz) than in other two groups (7–8 kHz). The acute bradycardia and moderate lung hemorrhage were noticeable in all groups of rats exposed to the shock wave loading. The onset of both corresponds to 110 kPa peak overpressure, according to the dose-response models. The immunostaining against immunoglobulin G (IgG) of brain sections of rats sacrificed 24-hours post-exposure indicated the diffuse blood-brain barrier breakdown in the brain parenchyma. We observed that the acute response as well as mortality is a non-linear function of peak overpressure and impulse ranges explored in this work.

Transportation systems subject the human body to varying levels of vibrations, which causes lower back pain. Some studies presents that exposure to vibrations of 1.3 m/s 2 for ten minutes a day can be harmful even for healthy people. With transportation systems being part of our daily lives it is useful to better predict the effects of vehicle induced oscillations on human via mathematical models. Anthropometry of a person is highly important when it comes to fitting the occupant to the seat with the restraint system together with their mass. Spaceflight travel further complicate matters since 4–6 cm increase in body height can occur during space flight and space vehicles must be designed to accommodate these changes.

Speech is one of the most fundamental forms of self-expression and communication in humans [1]. Voiced speech is produced by fluid-structure interactions that drive vocal fold oscillations, creating a periodic pressure oscillation in the vocal tract. This excitation has a fundamental frequency, typically ranging between 100 and 200 Hz, depending on the individual. Thousands of people lose this ability each year when they are forced to undergo a total laryngectomy, which removes the entire larynx, usually to prevent the spread of cancer. The American Cancer Society predicts there will be about 3,000 laryngectomees in the United States alone during 2013 [2][3].

Recent studies have shown that the supraglottic structures could alter the aeroacoustics output of the larynx [1–2]. The fist supraglottic tissue above the true vocal folds (TVF) is the false vocal folds (FVF) or ventricular folds. This non-oscillatory part of the human larynx shows a wide range of adductions during the normal phonation. Most previous studies, however, have focused on the effect of normal configuration of the FVFs based on mean values reported for this laryngeal structure. Therefore, the effect of different levels of FVF adduction on oscillation of the TVFs remained uninvestigated.

This research investigates the effect of pressure oscillation (PO) on the alveoli surface tension. Experimental and modeling simulations are used to show that introducing superimposed oscillations on the tidal volume excursion between 0–70Hz in a surfactant bubble lowers interfacial surface tension below values observed using tidal volume excursion alone. Evidently this makes it easier for an infant with RDS to maintain the required level of functional residual capacity without collapse.

Human speech is initiated when the lungs achieve a critical pressure forcing the vocal folds apart, expelling air through the glottis, and beginning self-sustained oscillations. The oscillations arise due to coupling between the aerodynamic forces and the structural properties of the vocal folds. During each phonation cycle the glottis transitions from a convergent channel upon opening, to a uniform, and finally a divergent channel before closing and repeating the cycle. The resulting pulsatile flow field which emanates from the vocal folds forms the raw component of speech.

Low and/or oscillatory Wall Shear Stress (WSS) has been correlated with elevated risk for increased intima media thickness and atherosclerosis in several studies during the last decades [1, 2]. Most of the studies have addressed laminar flows, in which the oscillations mainly are due to the pulsating nature of blood flow. Turbulent flows however show significant spatial and temporal fluctuations although the mean flow is steady.

Abnormal angiogenesis (formation of capillaries) plays an important role in the impaired diabetic wound healing and has emerged as a new target area for therapeutic interventions. Pulsed magnetic field therapy, which was initially used for healing of bone fractures, has been recently introduced as a potential therapy to treat diabetic and chronic wounds [1], although the mechanisms responsible for improved healing are still unclear. Electromagnetic fields (EMF) have been shown to act as a directional cues in cellular responses such as migration and activations of several signal transduction cascades [2]. Recent literature delineates an important role of GHz EMF (i.e., with an oscillation period of a fraction of a nanosecond) in inducing rapid and sustained phosphorylation of mitrogen-activated kinase and extracellular-signal-regulated kinase (MAPK/ERK) [3]. Recent studies have also implicated MAP kinase in mediating the phosphorylation of Connexin-43 (Cx43) that accompanies regulation of cell-cell communication via connexin gap junctions [4]. Importantly, both MAPK/ERK pathway and Cx43 signaling are involved in the process of angiogenesis [5,6]. Therefore, the goal of this study was to test the hypothesis that high-frequency (7.5GHz) EMFs promote angiogenesis in vitro via MAPK/ERK and/or Cx43 signaling. We used a custom-built EMF exposure setup and a self-assembling peptide nanoscaffold as a controlled angiogenic microenvironment [7] to quantify the effect of EMF on capillary formation and underlying cellular responses.

Voiced speech involves complex fluid-structure-acoustic interactions. When a critical lung pressure is achieved, the vocal folds are pushed apart inciting self-sustained oscillations. The interplay between the aerodynamic forces and the myoelastic tissue properties produces robust oscillation of the vocal folds. The pulsatile nature of the flow as it emanates from vocal folds creates an oscillatory pressure field which acoustically excites the vocal tract and ultimately forms intelligible sound. Recently, it has been shown that the acoustic pressures are high enough in magnitude that they modulate the static fluid pressures which drive the flow. 1 This coupling effect creates a feedback loop with the fluids, acoustics, and vocal fold dynamics becoming interconnected. Consequently, speech science investigations that aim to capture the relevant physics must consider all three components to yield credible, clinically-relevant results.

Chondrocytes play a critical role in cartilage remodeling by mediating the biosynthesis, organization, and modification of extracellular matrix (ECM) [1] . Previous studies showed that chondrocytes are highly sensitive to the surrounding mechanical and osmotic environments [2] . However, how these signals are perceived and transduced by chondrocytes remains unclear. One of the earliest responses of chondrocytes to stimuli is a transient oscillation in intracellular Ca 2+ concentration ([Ca 2+ ] i ) [3] . The major objective of this study was to investigate and compare the Ca 2+ signaling of chondrocytes, including both primary cells and chondrogenic cell line, under mechanical stimulus [4] and osmotic stress. The roles of seven essential pathways in Ca 2+ signaling were further examined using pharmacological inhibitors.

In asthma treatment β-agonists such as isoproterenol are used for their ability to relax airway smooth muscle (ASM) through stimulation of cAMP production. In vitro experiments conducted on ASM tissues suggest that length oscillations applied to contracted muscle result in a reduction in the contractile ability of the tissue. Conducting experiments on tissues from two different species leads to a fact that length oscillation enhances ASM relaxation induced by β-agonists agent independent of the species.

An advanced rheological technique was used to estimate the dynamic material properties of pediatric porcine vitreous. Validation of the technique was performed with two simulant materials. Interconversion of time-dependent data to frequency-dependent data resulted in good approximation of storage and loss modulus for a primarily viscous material, but resulted in an erroneous loss modulus for a primarily elastic material. This can likely be overcome by utilizing free oscillations resulting from creep testing. Porcine storage modulus was significantly lower in older animals, but additional testing is necessary to completely characterize the material properties of pediatric vitreous over a wide range of frequencies.

Mechanical stimuli such as fluid flow can induce robust multiple intracellular calcium ([Ca 2+ ] i ) peaks in connected bone cell networks [1]. This fluid flow induced oscillation of [Ca 2+ ] i can come from two sources: intracellular Ca 2+ stores (e.g., endoplasmic reticulum, ER) and the extracellular environment. Moreover, [Ca 2+ ] i signaling is mediated by various molecular pathways, such as IP 3 , ATP, PGE 2 , and NO. Osteocytes are believed to comprise a sensory network in bone tissue that monitors in vivo mechanical loading and triggers appropriate adaptive responses from osteoblasts and osteoclasts [2]. It is also well recognized that osteoblasts, the cells responsible for bone formation, can directly sense and respond to mechanical stimulation (e.g., fluid flow). In the present study, two types of cell networks were constructed in vitro with osteocyte-like and osteoblast-like cells, respectively, by using microcontact printing and self assembled monolayer (SAM) technologies. The calcium responses of the two types of cell networks to fluid flow were recorded, quantitatively analyzed, and compared. Then we examined how the [Ca 2+ ] i response in the osteocyte cell network was influenced by gap junctions, intra/extracellular calcium sources, and other various molecular pathways.

The dynamic response of contracted airway smooth muscles to a finite length change and longitudinal oscillations is described using a simplified model. The model is intended to interpret the biophysical events but not to accurately describe them. It shows that the value of tissue length changes have pronounced indications of cross-bridge detachment. However, the frequency of oscillations represents the velocity of the length change, which affects the cross-bridge cycling rate reflected in the low frequency range.

Voiced speech is initiated as air is expelled from the lungs and passes through the vocal tract inciting self-sustained oscillations of the vocal folds. While various approaches exist for investigating both normal and pathological speech, the relative inaccessibility of the vocal folds make multi-mass speech models an attractive alternative. Their behavior has been benchmarked with excised larynx experiments, and they have been used as analysis tools for both normal and disordered speech, including investigations of paralysis, vocal tremor, and breathiness. However, during pathological speech, vocal fold motion is often unstructured, resulting in chaotic motion and a wealth of nonlinear phenomena. Unfortunately, current methodologies for multi-mass speech models are unable to replicate the nonlinear vocal fold behavior that often occurs in physiological diseased voice for realistic values of subglottal pressure.