High-amplitude Waves Research Articles

Are sleep complaints following mild traumatic brain injury associated with changes in the characteristics of sleep slow waves?

Slow waves (SW) are low frequency ( < 4 Hz) and high amplitude ( > 75 μ V ) waves that occur during non-rapid eye movement (NREM) sleep, and which are known to play a crucial role in synaptic plasticity and in the restorative function of sleep. In the present study, we sought to determine if changes in SW characteristics are observed after a mild traumatic brain injury (mTBI) and whether SW characteristics are associated with sleep complaints, which are reported by approximately 30–80% of individuals with mTBI. 34 mTBI subjects (mean age 34,2 ± 11,9 yrs) and 33 controls (mean age; 31,5 ± 11,4 yrs) matched for age, sex and education were included. Subjects with mTBI were tested on average 10,5 ± 10,4 weeks after their brain injury. All subjects underwent a laboratory polysomnography and filled out the Pittsburgh Sleep Quality Inventory (PSQI) and the Beck Depression Index (BDI). Student t -tests were used to compare groups on demographic characteristics, PSQI scores, BDI scores and sleep architecture. ANOVA with one repeated measure (sleep cycles (1 to 4)) were performed on C3 lead to compare groups for the following SW characteristics: density, amplitude, frequency, negative/positive phase duration and slope. Association between SW characteristics, clinical features, PSQI scores and BDI scores were measured in the mTBI group using Pearson partial correlations with age as a covariable. We found higher BDI scores in mTBI compared to control subjects ( t (52) = 6,1; p < 0,001), reflecting more depression symptoms in the mTBI group. Subjects with mTBI also reported more sleep disturbances on the PSQI questionnaire compared to control subjects ( t (52) = 6,3; p < 0,001). However, no significant group differences were found for sleep architecture and for SW characteristics. There were no significant correlations between SW characteristics, clinical features, PSQI and BDI scores. Individuals with mTBI report depression symptoms and sleep disturbances, but these symptoms were not associated with altered sleep architecture or SW characteristics. Supported by the Canadian Institutes of Health Research and the Fonds de recherche du Québec – Santé.

A new class of exact solutions of the Klein–Gordon equation of a charged particle interacting with an electromagnetic plane wave in a medium

Exact solutions are presented of the Klein–Gordon equation of a charged particle moving in a transverse monochromatic plasmon wave of arbitrary high amplitude, which propagates in an underdense plasma. These solutions are expressed in terms of Ince polynomials, forming a doubly infinite set, parametrized by discrete momentum components of the charged particle’s de Broglie wave along the polarization vector and along the propagation direction of the plasmon radiation. The envelope of the exact wavefunctions describes a high-contrast periodic structure of the particle density on the plasma length scale, which may have relevance in novel particle acceleration mechanisms.

Tuning stem cell fate with physical energies

Defocused extracorporeal low-energy shock waves (DLSW) have long been used successfully in the treatment of bone and joint diseases as well as in the management of pain and inflammatory conditions. Shock waves are generated by an underwater highvoltage condenser spark discharge and focused at the diseased area, using an elliptic reflector. Shock waves are high-amplitude sound waves from a transient pressure disturbance that propagate in three-dimensional space with a sudden increase from ambient pressure to maximum pressure at the wave front. A shock wave is a sonic pulse that has certain physical characteristics. There is an initial increase of a high peak pressure, sometimes >100 MPa (500 bar) within <10 ns, followed by a low tensile amplitude (up to 10 MPa), a short life cycle of approximately 10 ms and a broad-frequency spectrum of 16e20 MHz. There are two basic effects of shock waves: The primary effect is direct generation of mechanical forces that result in the maximally beneficial pulse energy concentrated at the point where treatment is to be provided, and the secondary effect is indirect mechanical forces by cavitation, which may cause a negative effect or damage to the tissues. In the current issue of Cytotherapy, Zhao et al. (1) investigated the effects produced by DLSW on stem cell homeostasis in vitro. The authors used an electromagnetic shock wave machine and exposed rat bone marrow-derived stem cells (BMSCs) to 800 impulses of DLSW at an energy flux density of 0.1 mJ/mm. This treatment was performed before each passage. The shocked BMSCs were found to secrete more vascular endothelial growth factor and CXC ligand 5 than the BMSCs that were not shocked. The expression of CD166, CD44 and CD34 was not affected. The shocked BMSCs also exhibited higher

Analysis of acoustic harmonic generation in a solid with multiple nonlinear interfaces

Weak bonds and delaminations are typical examples of imperfect interfaces in multilayered structures. Nonlinear acoustic/ultrasonic methods are expected to offer a promising means to monitor these imperfect interfaces, as such interfaces behave nonlinearly when subjected to high-amplitude waves and result in the occurrence of nonlinear frequency components such as higher harmonics. Harmonic generation at a single nonlinear interface has been studied by many investigators from both theoretical and experimental points of view. In this presentation, a theoretical analysis of harmonic generation at multiple nonlinear interfaces is presented within a framework of one-dimensional elastic wave propagation in the frequency domain. The analysis is based on the perturbation expansion of the wave field by assuming the weak nonlinearity. Specifically, the second-harmonic generation is analyzed by first solving the linear transmission of the incident fundamental component, and then the propagation of the second-harmonic components generated at nonlinear interfaces. Some numerical results are demonstrated and compared to the results of time-domain analysis using the finite element method. The present analysis shows that harmonic generation in multilayered solids is remarkably frequency-dependent, as both the fundamental and the harmonic components interact with the layered structure in a complex manner.

Investigation on the generation mechanisms of acoustic streaming in a thermoacoustic prime mover

High-amplitude acoustic waves in thermoacoustic devices are responsible for the generation of a secondary flow called acoustic streaming. Superimposed on the oscillating flow, this secondary flow is an important source of energy dissipation. To remove acoustic streaming would result in substantial improvements in the energy performance of thermoacoustic devices. Understanding the control parameters and mechanisms of streaming generation is essential for controlling acoustic streaming.In this paper, streaming sources are investigated in a pressurized thermoacoustic prime mover. The device was designed and built at the LIMSI (Laboratoire d’Informatique pour la Mécanique et les Sciences de l’Ingénieur) to investigate acoustic streaming. To calculate the theoretical velocity in the thermoacoustic device, the usual modelings were extended to take into account the cross section variation. Measurements of acoustic streaming velocity performed by Laser Doppler Velocimetry are compared to the theoretical results. Finally, the good agreements obtained led to the validation of the theory. The validated theory was then used to study the mechanisms of streaming generation in order to determine their influences in the thermoacoustic prime mover and therefore reducing the secondary flow. Thereafter, the investigation was extended to four channels with different widths and according to results of the literature, the proportion of outer streaming compared to inner streaming decreases when the channel width decrease. The investigation showed that the mechanisms of acoustic streaming generation differ for large and narrow channels.

Microscopic characterization of defect structure in RDX crystals

Three batches of the commercial energetic material RDX, as received from various production locations and differing in sensitivity towards shock initiation, have been characterized with different microscopic techniques in order to visualize the defect content in these crystals. The RDX crystals are embedded in an epoxy matrix and cross-sectioned. By a treatment of grinding and polishing of the crystals, the internal defect structure of a multitude of energetic crystals can be visualized using optical microscopy, scanning electron microscopy and confocal scanning laser microscopy. Earlier optical micrographs of the same crystals immersed in a refractive index matched liquid could visualize internal defects, only not in the required detail. The combination of different microscopic techniques allows for a better characterization of the internal defects, down to inclusions of approximately 0.5 μm in size. The defect structure can be correlated to the sensitivity towards a high-amplitude shock wave of the RDX crystals embedded in a polymer bonded explosive. The obtained experimental results comprise details on the size, type and quantity of the defects. These details should provide modellers with relevant and realistic information for modelling defects in energetic materials and their effect on the initiation and propagation of shock waves in PBX formulations.

Analytic approximation to nonlinear hydroelastic waves traveling in a thin elastic plate floating on a fluid

An analytic approximation method known as the homotopy analysis method (HAM) is applied to study the nonlinear hydroelastic progressive waves traveling in an infinite elastic plate such as an ice sheet or a very large floating structure (VLFS) on the surface of deep water. A convergent analytical series solution for the plate deflection is derived by choosing the optimal convergencecontrol parameter. Based on the analytical solution the effects of different parameters are considered. We find that the plate deflection becomes lower with an increasing Young’s modulus of the plate. The displacement tends to be flattened at the crest and be sharpened at the trough as the thickness of the plate increases, and the larger density of the plate also causes analogous results. Furthermore, it is shown that the hydroelastic response of the plate is greatly affected by the high-amplitude incident wave. The results obtained can help enrich our understanding of the nonlinear hydroelastic response of an ice sheet or a VLFS on the water surface.

Investigation of the Velocity Field in the Wave Rivulet Flowing Down the Vertical Plate

Joint measurements of thickness and fluid velocity in wavy rivulets were performed using PIV and LIF methods. The stagnant regions in which fluid moves with the velocity of the waves were found under the humps of low-frequency highamplitude waves. The profiles of longitudinal velocity of the fluid were reconstructed for different regions of the waves. These profiles greatly deviate from self-similar parabolic profiles in the stagnant regions and in the regions of capillary precursor of the waves

Enhanced excitability of thalamic sensory neurons and slow-wave EEG pattern after stimuli that induce spinal long-term potentiation.

Spinal nociceptive neurons are well known to undergo a process of long-term potentiation (LTP) following conditioning by high-frequency sciatic nerve stimulation (HFS) at intensities recruiting C-fibers. However, little if any information exists as to whether such HFS conditioning that produces spinal LTP affects sensory transmission at supraspinal levels. The present study explored this possibility. Conventional extracellular recording methods were used to examine the consequences of HFS versus sham HFS conditioning on individual wide-dynamic range thalamic neurons located in the ventro-postero-lateral (VPL) nucleus in isoflurane-anesthetized rats. Following HFS, the ongoing firing rate and stimulus-evoked (brush, pinch, sciatic nerve) responses were markedly enhanced as were responses to juxtacellular, microiontophoretic applications of glutamate. These HFS-induced enhancements lasted throughout the recording period. Sham stimuli had no effect on VPL neuron excitability. Cortical electroencephalographic (EEG) wave activities were also measured around HFS in conjunction with VPL neuron recordings. The cortical EEG pattern under baseline conditions consisted of recurring short duration bursts of high-amplitude slow waves followed by longer periods of flat EEG. Following HFS, the EEG shifted to a continuous large-amplitude, slow-wave pattern within the 0.5-8.0 Hz bandwidth lasting throughout the recording period. Sham HFS did not alter EEG activity. Sciatic nerve conditioning at A-δ fiber strength, known to reverse spinal LTP, did not alter enhanced neuronal excitability or the EEG slow-wave pattern induced by HFS. These data support the concept that HFS conditioning of the sciatic nerve, which leads to spinal LTP, is associated with distinct, long-lasting changes in the excitability of neurons comprising thalamocortical networks.

Detection of gravity waves across the USArray: A case study

Barometers deployed as part of the USArray Transportable Array (TA) recorded large (300 Pa peak-to-peak) gravity waves, or gust fronts, that originated near a severe tornadic storm system in the southern United States on April 27, 2011. We present a new method in which the TA is divided into a large number of elemental sub-arrays. Each 3-element sub-array (triad) is sufficiently closely spaced so that the long-period gravity wave signal is coherent, but large enough to provide a robust estimate of the signal's direction and speed. The results from each triad are combined to follow the progress of gravity waves as they propagate across the TA over 2 days in late April, 2011. We observe a large, high-amplitude gravity wave, spanning a region over 200,000 km2, progressing to the NNW away from the tornadic storm region. We also observe gravity waves with lower amplitudes and smaller spatial extent along the gulf coast, propagating southward, away from the storm region. This study demonstrates the functionality of the USArray pressure sensors for analyzing gravity wave dynamics over periods greater than 40 min and across a wide region. In principle the method could be applied to study other long-period wave phenomena recorded by any dense large-scale network and is not limited to gravity waves.

Kleine-Levin syndrome and bipolar disorder: a differential diagnosis of recurrent and resistant depression

Kleine-Levin syndrome (KLS) is a rare sleep disorder (1-2 reported cases per one million individuals) primarily affecting young subjects. Episodes are characterized by hypersomnia, cognitive impairment, feelings of derealization, and, less frequently, hyperphagia (66%), hypersexuality [53% (principally men)], and depressed mood [53% (predominantly women)]. KLS cases are frequently misdiagnosed and pose therapeutic challenges (i.e., amantadine and mood stabilizers are only marginally effective). The cause of KLS is unknown, but an association between KLS and mood disorders has been suggested by some clinical analogies. We report the case of a 44-year-old Caucasian woman with bipolar I disorder referred by her psychiatrist to our psychiatric center for recurrent and resistant major depression according to DSM-IV-TR criteria. Following examination, we confirmed the diagnoses of bipolar I disorder and KLS. The patient experienced about 15 evenly distributed KLS episodes, each lasting about one week, which occurred during the six years following her first manifestation at age 18 years. An electroencephalogram was performed during a KLS episode and showed high-amplitude theta waves in the left and right temporal lobes, with predominance in the left hemisphere. The pronounced bipolar disorder symptomatology, starting at 15 years of age with major depression and a suicide attempt, had impeded the identification of KLS, which was not diagnosed until the age of 42. Bipolar disorder may obscure KLS, with each condition adversely affecting the course of the other, and consequently, the co-occurrence of KLS and bipolar disorder may be underestimated. KLS and bipolar disorder may share common vulnerability factors, such as immune-inflammatory and circadian disturbances, and there may be a genetic predisposition for both. Additionally, mood stabilizers may be effective for KLS and bipolar disorder.

Ketamine, Sleep, and Depression: Current Status and New Questions

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has well-described rapid antidepressant effects in clinical studies of individuals with treatment-resistant major depressive disorder (MDD). Preclinical studies investigating the effects of ketamine on brain-derived neurotrophic factor (BDNF) and on sleep slow wave activity (SWA) support its use as a prototype for investigating the neuroplastic mechanisms presumably involved in the mechanism of rapidly acting antidepressants. This review discusses human EEG slow wave sleep parameters and plasma BDNF as central and peripheral surrogate markers of plasticity, and their use in assessing ketamine's effects. Acutely, ketamine elevates BDNF levels, as well as early night SWA and high-amplitude slow waves; each of these measures correlates with change in mood in depressed patients who respond to ketamine. The slow wave effects are limited to the first night post-infusion, suggesting that their increase is part of an early cascade of events triggering improved mood. Increased total sleep and decreased waking occur during the first and second night post infusion, suggesting that these measures are associated with the enduring treatment response observed with ketamine.

Clinical and genetic characteristics of glucose transporter type 1 deficiency syndrome

To analyze the clinical and SLC2A1 gene mutation characteristics of glucose transporter type 1 deficiency syndrome. The detailed clinical manifestations of six cases were recorded. The laboratory tests including EEG, MRI, blood chemistry, and lumbar puncture were performed. SLC2A1 gene mutations were analyzed by PCR, DNA sequencing and multiplex ligation-dependent probe amplification (MLPA). Patient 1, 2 and 3 had classical clinical symptoms including infantile onset seizures, development delay. Patient 4, 5 and 6 had non-classical clinical symptoms including paroxysmal behavior disturbance, weakness, ataxia, lethargy, especially after fasting or exercise, without severe seizures. The plasma glucose levels were normal. The CSF glucose levels decreased in all the six cases, ranged from 1.10 mmol/L to 2.45 mmol/L, the mean level was 1.68 mmol/L. The CSF glucose/plasma glucose ratios decreased, ranged from 0.16 to 0.51, the mean ratio was 0.34. Four patients had normal EEG. Two patients had focal and diffuse epileptiform discharge, and one of them also had paroxysmal occipital or generalized high-amplitude slow waves during awake and sleep time. MRI abnormalities were found in three patients, patient 1 with mild brain atrophy, patient 3 with bilateral ventricle plump, and patient 4 with high signals in T2 in the frontal and occipital white matter, interpreted as hypomyelination. SLC2A1 gene mutations were found in six cases. Patient 1 has large scale deletion in exon 2. In patient 2 to 6, the mutations were c.741 G>A (E247K), 599delA, 761delA, c.1148 C>A (P383H), c.1198 C>T (R400C) respectively. Two patients were treated with ketogenic diet. The seizures disappeared and development became normal. Three patients responded to frequent meals with snacks. One patient refused any treatments, the symptoms continued to exist. The clinical manifestations of glucose transporter type 1 deficiency syndrome are varied. The common symptoms included infantile onset seizures and various paroxysmal events. These neurologic symptoms generally fluctuated and were influenced by factors such as fasting or fatigue. This feature could be a very important clue for the diagnosis of GLUT1-DS. Lumbar puncture is recommended in patients with episodic CNS symptoms especially after fasting. GLUT1-DS is a treatable neurometabolic disorder, early diagnosis and treatment may improve the prognosis of the patients.

Modern internal waves and internal tides along oceanic pycnoclines: Challenges and implications for ancient deep-marine baroclinic sands

Thus far, the subject of deep-marine sands emplaced by baroclinic currents associated with internal waves and internal tides as potential reservoirs has remained an alien topic in petroleum exploration. Internal waves are gravity waves that oscillate along oceanic pycnoclines. Internal tides are internal waves with a tidal frequency. Internal solitary waves (i.e., solitons), the most common type, are commonly generated near the shelf edge (100–200 m [328–656 ft] in bathymetry) and in the deep ocean over areas of sea-floor irregularities, such as mid-ocean ridges, seamounts, and guyots. Empirical data from 51 locations in the Atlantic, Pacific, Indian, Arctic, and Antarctic oceans reveal that internal solitary waves travel in packets. Internal waves commonly exhibit (1) higher wave amplitudes (5–50 m [16–164 ft]) than surface waves (2 m [6.56 ft]), (2) longer wavelengths (0.5–15 km [0.31–9 mi]) than surface waves (100 m [328 ft]), (3) longer wave periods (5–50 min) than surface waves (9–10 s), and (4) higher wave speeds (0.5–2 m s–1 [1.64–6.56 ft s–1]) than surface waves (25 cm s–1 [10 in. s–1]). Maximum speeds of 48 cm s–1 (19 in. s–1) for baroclinic currents were measured on guyots. However, core-based sedimentologic studies of modern sediments emplaced by baroclinic currents on continental slopes, in submarine canyons, and on submarine guyots are lacking. No cogent sedimentologic or seismic criteria exist for distinguishing ancient counterparts. Outcrop-based facies models of these deposits are untenable. Therefore, potential exists for misinterpreting deep-marine baroclinic sands as turbidites, contourites, basin-floor fans, and others. Economic risks associated with such misinterpretations could be real.

Double beamforming processing in a seismic prospecting context

The use of larger numbers of sensors is becoming more common at the large, continental scale for deep-structure imaging in seismology, and at a smaller scale with exploration geophysics objectives. Seismic arrays require array processing from which new types of observables contribute to a better understanding of the wave propagation complexity. From among these array processing techniques, this study focuses on a way to select and identify different phases between two source-receiver arrays based on the double beamforming (DBF) method. At the exploration geophysics scale, the goal is to identify and separate low-amplitude body waves from high-amplitude dispersive surface waves. A synthetic data set from a finite-difference time-domain simulation is first used to validate the array processing method. From directional information obtained with DBF, and due to the double-plane wave projection, it is demonstrated that surface and body waves can be extracted with a higher efficacy compared to classical beamforming even at short offset. A seismic prospecting data set in a laterally heterogeneous medium is then investigated. This data set is a high-resolution survey which provides a perfect control on source and receiver arrays geometry. The separation between the direct surface and body waves is observed after DBF and ray bending is discussed from the additional azimuthal information.

Combined surface and borehole seismic imaging in a hard rock terrain: A field test of seismic interferometry

Seismic images are inherently directionally biased by the source-receiver geometry. This directional bias is particularly problematic for seismic imaging in hard rock terrains where structural dips may have any orientation with respect to the surface. We tested a technique for partially mitigating directional bias by combining surface and borehole seismic data and evaluated the results of a first field test of the technique. In this technique, surface data acquired using standard 2D acquisition procedures were combined with borehole data derived from a walk-away vertical seismic profile (VSP). The VSP data were transformed into the borehole datum using seismic interferometry. The interferometry created virtual shot records comprising sources and receivers in the borehole. The virtual shot records were then processed, using standard common midpoint techniques, resulting in an image from the borehole datum. The combination of the surface and borehole data increased the range of illumination angles resulting in seismic images that included reflections from structures with a wider range of dips than is available to surface profiling alone. The field test demonstrated that the surface and borehole data provide complementary information, which is more than either data set alone can provide. The test also verified the robustness of the virtual source technique even when the original VSP data are highly contaminated by high-amplitude tube waves. These results demonstrated that the combined imaging approach has significant potential for application in the polydeformed hard rock domains often encountered in minerals exploration.

Turbulence and columnar vortex formation through inertial-wave focusing

In this experimental and numerical study, we consider the role of inertial waves in the inverse energy cascade and the transfer of momentum in a rotating fluid. An oscillating torus generates two inertial-wave cones with their energy focusing at their apex. For high wave amplitudes, turbulence is generated locally around the focal point, resulting in angular momentum mixing and the generation of a columnar cyclonic vortex. The results suggest that nonlinear dynamics is essential for the wave induced momentum transport towards columnar vortices in rotating turbulence.

Two-phase damage models of magma-fracturing

Damage and fracturing in two-phase and porous flows are relevant for geological process such as magma-fracturing during melt migration, which is associated with the propagation of a pore-generating damage front ahead of high-pressure fluid injection. We therefore examine the propagation of porous flow in a damageable matrix by applying the two-phase theory for compaction and damage proposed by Bercovici et al. (2001a) and Bercovici and Ricard (2003). The movement of the fluid and the solid is governed by the two-phase flow laws, while damage (void generation and microcracking) is treated by considering the generation of interfacial surface energy by deformational work. Calculations of one-dimensional (1-D) flow of fluid migrating buoyantly through compacting and damageable matrix show that damage is mitigated in steady-state largely because of the loss of the velocity gradient at the fluid front. However, in time-dependent flows, linear stability analysis shows that the propagation velocity of porosity waves is strongly dependent on damage. In the damage-free case porosity waves are dispersive in that wave-speed decreases with wavenumber (inverse wavelength); however with damage the dispersion flattens and beyond a critical damage reverses (the wave speed increases with wavenumber). Since normal dispersive behavior balances breaking in the nonlinear wave case, such reversed dispersion implies that damage has a profound effect in the nonlinear limit by facilitating wave front steepening and higher wave velocities. Nonlinear solitary wave solutions are obtained numerically and show that the transmission of porosity waves induces high stress and damage that can push the damage front forward. With damage the porosity waves sharpen and calculations suggest that they can transform from shape-conserving solitary waves into faster high amplitude waves, which is also predicted by the linear theory. Such pulse-like sharper waves may prove effective at promoting fluid migration through magma-fracturing.

A typical wave wake from high-speed vessels: its group structure and run-up

Abstract. High-amplitude water waves induced by high-speed vessels are regularly observed in Tallinn Bay, the Baltic Sea, causing intense beach erosion and disturbing marine habitants in the coastal zone. Such a strong impact on the coast may be a result of a certain group structure of the wave wake. In order to understand it, here we present an experimental study of the group structure of these wakes at Pikakari beach, Tallinn Bay. The most energetic vessel waves at this location (100 m from the coast at the water depth 2.7 m) have amplitudes of about 1 m and periods of 8–10 s and cause maximum run-up heights on a beach up to 1.4 m. These waves represent frequency modulated packets where the largest and longest waves propagate ahead of other smaller amplitude and period waves. Sometimes the groups of different heights and periods can be separated even within one wave wake event. The wave heights within a wake are well described by the Weibull distribution, which has different parameters for wakes from different vessels. Wave run-up heights can also be described by Weibull distribution and its parameters can be connected to the parameters of the distribution of wave heights 100 m from the coast. Finally, the run-up of individual waves within a packet is studied. It is shown that the specific structure of frequency modulated wave packets, induced by high-speed vessels, leads to a sequence of high wave run-ups at the coast, even when the original wave heights are rather moderate. This feature can be a key to understanding the significant impact on coasts caused by fast vessels.

Foreshock compressional boundaries observed by Cluster

Recent global hybrid simulations (kinetic ions, fluid electrons) of the solar wind interaction with Earth's magnetosphere revealed the existence of a new structure at the edges of the foreshock, named foreshock compressional boundary (FCB). The FCB is associated with a strong compression of magnetic field magnitude and density followed by strong decreases of these two quantities. This structure represents a transition region that separates the highly disturbed foreshock plasma from the solar wind. Hybrid simulations have shown that the formation and strength of the FCB depend on the generation and nonlinear evolution of ultra‐low frequency (ULF) waves which in turn have been produced by the interaction of foreshock backstreaming ions with the solar wind. In this work, we use Cluster magnetic field and plasma data to show that the FCB exists and is frequently observed in the foreshock region. We study FCB properties during 36 crossings for different interplanetary field geometries and solar wind speeds. The results presented here reveal that FCBs form for different solar wind conditions (i.e., cone angle, velocity), and are highly nonlinear structures with δB/Bo and δn/no amplitudes around 40% of the ambient values. We find that the FCB is sometimes a transition region between the pristine solar wind plasma and the foreshock plasma. At other times, it separates a region with large amplitude waves from regions with high frequency small amplitude waves. Preliminary analysis of ion distributions show that in some cases the FCB can coincide with the ULF wave boundary and in others with the intermediate ion boundary. Cluster data also show that the solar wind flow is decelerated and deviated when crossing the FCB.