Asymmetric Expansion Research Articles

Local heat transfer downstream of an asymmetric abrupt expansion and cavity in a circular tube

This study is concerned with measuring local heat transfer downstream of an asymmetric abrupt expansion and an asymmetric abrupt expansion followed by an asymmetric abrupt contraction (called “asymmetric cavity”) in a circular tube at a uniform wall temperature. The effects of geometry and three-dimensionality of the flow caused by asymmetric expansion on heat transfer characteristics are also examined. The flow just upstream of the expansion is unheated and fully developed at the entrance to the heated asymmetric abrupt expansion region. Local heat transfer coefficients are measured using a specially designed isothermal heat flux sensor. Measurements for the asymmetric abrupt expansion are made at a small to large diameter ratio of d/D = 0.4 and 0.533 for Reynolds numbers of ReD = 17,300 and 21,900, respectively. The eccentricities of the tube axis (e/D) are 0.25 and 0.17 for d/D = 0.4, and 0.195 and 0.065 for d/D = 0.533. For the asymmetric cavity, all tests are made at d/D = 0.4 and ReD = 17,300 with various cavity lengths for e/D = 0 and 0.25, respectively. For both cases, the variations of local Nusselt number are observed along the wall of downstream circular tube at several angular positions around the tube circumference. In general, the local Nusselt numbers downstream of an asymmetric abrupt expansion are substantially higher than the fully developed values for the range of Reynolds numbers, diameter ratios and eccentricities investigated, due to high turbulence and mixing action in the recirculation region. And the maximum Nusselt numbers occur between 10 and 15 step heights from the expansion step. The Nusselt number distributions for the asymmetric cavity show a dramatic increase to the maximum values as the downstream region of the cavity is approached. This behavior is attributed to a periodic vortex shedding, subsequent impingement on the downstream corner region of the cavity and three-dimensionality effects which cause an increase in turbulence intensity.

An alternative choice: Obtaining space for a canine with asymmetric fan type expansion appliance

A 12-year old female patient presented with her unesthetic appearance while smiling. The patient had a vestibule positioned upper-left canine, beside mesofacial face type, flat profile, Class II molar and canine relationships clinically. Dental crowding was 7.8 mm in the upper arch and 4.1 mm in the lower. Treatment plan included to obtain space for the upper-left canine using a modified fan type expansion appliance, followed by comprehensive fixed orthodontic treatment. The aim of this case report is to present a non-extraction treatment of a patient using asymmetric fan type expansion appliance.

1+1=3? Concerted Action of Membrane Permeabilizers

Certain antibiotic peptides are thought to permeabilize membranes of pathogens by effects that are also observed for simple detergents, such as membrane thinning and disordering, asymmetric bilayer expansion, toroidal pore formation, and micellization. Here we test the hypothesis that such peptides act additively with detergents when applied in parallel. Additivity is defined analogously to a fractional inhibitory concentration index (FICI) of unity, and the extent and mechanism of leakage are measured by the fluorescence lifetime-based vesicle leakage assay using calcein-loaded vesicles. Concerted action was tested for the detergent C12EO8 with the detergents octyl glucoside and CHAPS, the antimicrobial peptide magainin 2, and the fungicidal lipopeptides surfactin, fengycin and iturin from Bacillus subtilis QST713, respectively. The results are discussed in terms of an optimum heterogeneity of the system that governs the leakage mechanism, extent of leakage, and additivity of action with another agent. The results are important for understanding the nature of detergent-like actions of peptides as well as for optimizing formulations of such antimicrobials for medical applications or crop protection.

What determines a leaf's shape?

The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Significant contributions have come from megaphyllous leaves, characterized usually as flat, thin lamina entrenched with photosynthetic organelles and stomata, which serve as the basis of primary productivity. During the course of evolution, the megaphylls have attained complexity not only in size or venation patterns but also in shape. This has fascinated scientists worldwide, and research has progressed tremendously in understanding the concept of leaf shape determination. Here, we review these studies and discuss the various factors that contributed towards shaping the leaf; initiated as a small bulge on the periphery of the shoot apical meristem (SAM) followed by asymmetric outgrowth, expansion and maturation until final shape is achieved. We found that the underlying factors governing these processes are inherently genetic: PIN1 and KNOX1 are indicators of leaf initiation, HD-ZIPIII, KANADI, and YABBY specify leaf outgrowth while ANGUSTIFOLIA3 and GROWTH-REGULATING FACTOR5 control leaf expansion and maturation; besides, recent research has identified new players such as APUM23, known to specify leaf polarity. In addition to genetic control, environmental factors also play an important role during the final adjustment of leaf shape. This immense amount of information available will serve as the basis for studying and understanding innovative leaf morphologies viz. the pitchers of the carnivorous plant Nepenthes which have evolved to provide additional support to the plant survival in its nutrient-deficient habitat. In hindsight, formation of the pitcher tube in Nepenthes might involve the recruitment of similar genetic mechanisms that occur during sympetaly in Petunia.

Energetic View on Membrane Pore Formation

Energetic View on Membrane Pore Formation

The novel use of three-dimensional surface models to quantify and visualise the immediate changes of the mid-facial skeleton following rapid maxillary expansion

BackgroundThe transverse skeletal effects of rapid maxillary expansion (RME) have previously been assessed using cone-beam CT (CBCT). However, to date the majority of studies assess the changes based on two-dimensional slice images, which under utilises the three-dimensional (3D) data captured. This study optimizes the volumetric CBCT data by generating 3D rendered surface models to quantity and visualize the immediate 3D changes of the mid-facial bone surfaces following RME. MethodsThe sample consisted of 14 patients who required RME prior to fixed appliances. Pre-treatment (T0) and immediate post expansion (T1) CBCT images were taken. Following superimposition the mid face was divided into six anatomical regions. A one-sample t-test was used to determine if the differences between the two surfaces were significantly ≥0.5 mm. FindingsAll regions showed a change following RME ≥ 0.5 mm. The maxillary and nasal bones showed 2.3 mm and 2.4 mm expansion respectively, followed by the zygomatic bones (1.4 mm), 2 cases showing asymmetric expansion. ConclusionsThe use of 3D surface rendered models allows quantification and visualisation of 3D changes in the mid-facial skeleton at anatomical sites distant of RME activation. Following activation there can be a pan mid-facial expansion, including not only the maxilla but also the nasal lateral bones and zygomas. The response was highly variable and asymmetric expansion can occur.

Asymmetric magnetic domain-wall motion by the Dzyaloshinskii-Moriya interaction

We demonstrate here that ultrathin ferromagnetic Pt/Co/Pt films with perpendicular magnetic anisotropy exhibit a sizeable Dzyaloshinskii-Moriya interaction (DMI) effect. Such a DMI effect modifies the domain-wall (DW) energy density and consequently, results in an asymmetric DW expansion driven by an out-of-plane magnetic field under an in-plane magnetic field bias. From an analysis of the asymmetry, the DMI effect is estimated to be strong enough for the DW to remain in the N\'eel-type configuration in contrast to the general expectations of these materials. Our findings emphasize the critical role of the DMI effect on the DW dynamics as the underlying physics of the asymmetries that are often observed in spin-transfer-related phenomena.

Extremely Wide and Asymmetric Anterior Decompression Causes Postoperative C5 Palsy

Single-center retrospective study. We examined whether extremely wide and asymmetric anterior decompression causes postoperative C5 palsy. Postoperative C5 palsy is a complication of cervical decompression surgery. We hypothesized that C5 palsy may be caused by nerve root impairment through extremely wide and asymmetric dural expansion due to unilateral predominant wide anterior decompression with concomitant C4-C5 foraminal stenosis. The study included 32 patients with postoperative C5 palsy from a cohort of 459 patients who underwent anterior cervical decompression and fusion at the C4-C5 disc level for cervical myelopathy. The 64 upper extremities were divided into 2 groups according to palsy side (n = 35) or nonpalsy side (n = 29). Also, to correlate radiological findings, 66 consecutive patients who underwent anterior cervical decompression and fusion without postoperative C5 palsy were selected as control. In patients with C5 palsy, the unilateral decompression width on the palsy side was significantly larger than that on the nonpalsy side (8.63 vs. 6.92 mm, P = 0.0003). In addition, the decompression width was significantly larger (15.69 vs. 14.38 mm, P = 0.02), the diameter of the C4-C5 foramen was significantly smaller (2.73 vs. 3.24 mm, P = 0.0008), the anterior spinal cord shift was significantly smaller (0.14 vs. 0.73 mm, P< 0.0001), and significant decompression asymmetry (0.74 vs. 0.89, P = 0.0003) was present in the patients with C5 palsy compared with controls. Extremely wide and asymmetric decompression concomitant with pre-existing C4-C5 foraminal stenosis may cause postoperative C5 palsy. Our findings should be valuable for surgeons considering anterior cervical decompression and fusion that includes the C4-C5 level. Surgeons should consider restriction of the decompression width to less than 15 mm and avoiding asymmetric decompression to reduce the incidence of C5 palsy.

Acute Effects of Volume-Oriented Incentive Spirometry on Chest Wall Volumes in Patients After a Stroke

The aim of the present study was to assess how volume-oriented incentive spirometry applied to patients after a stroke modifies the total and compartmental chest wall volume variations, including both the right and left hemithoraces, compared with controls. Twenty poststroke patients and 20 age-matched healthy subjects were studied by optoelectronic plethysmography during spontaneous quiet breathing (QB), during incentive spirometry, and during the recovery period after incentive spirometry. Incentive spirometry was associated with an increased chest wall volume measured at the pulmonary rib cage, abdominal rib cage and abdominal compartment (P = .001) and under 3 conditions (P < .001). Compared with healthy control subjects, the tidal volume (VT) of the subjects with stroke was 24.7, 18.0, and 14.7% lower during QB, incentive spirometry, and postincentive spirometry, respectively. Under all 3 conditions, the contribution of the abdominal compartment to VT was greater in the stroke subjects (54.1, 43.2, and 48.9%) than in the control subjects (43.7, 40.8, and 46.1%, P = .039). In the vast majority of subjects (13/20 and 18/20 during QB and incentive spirometry, respectively), abdominal expansion precedes rib cage expansion during inspiration. Greater asymmetry between the right and left hemithoracic expansions occurred in stroke subjects compared with control subjects, but it decreased during QB (62.5%, P = .002), during incentive spirometry (19.7%), and postincentive spirometry (67.6%, P = .14). Incentive spirometry promotes increased expansion in all compartments of the chest wall and reduces asymmetric expansion between the right and left parts of the pulmonary rib cage; therefore, it should be considered as a tool for rehabilitation.

Game of Platforms: Strategic Expansion in Two-Sided Markets

Online platforms, such as Google, Facebook, or Amazon, are constantly expanding their activities, while increasing the overlap in their service offering. In this paper, we study the scope and overlap of online platforms' activities, when they are endogenously determined. We model an game between two online platforms offering two different services to users for free, while selling user clicks to advertisers. At the outset, each platform offers one service, and users may subscribe to one platform or both (multihoming). In the second stage, each platform decides whether to expand by adding the service already offered by its rival. Platforms' decisions affect users' mobility, and thus the partition of users in the market, which, in turn, affects platform prices and profits. We analyze the equilibrium of the game, demonstrating that, in equilibrium, platforms may decide not to expand, even though is costless. Such strategic no expansion decisions are due to quantity and price effects of changes in user mobility, brought on by expansion. Both symmetric and symmetric no-expansion equilibria may arise, as well as asymmetric equilibria, even for initially symmetric platforms.

Asymmetric oscillatory expansion of a cylindrical plasma

AbstractAsymmetric oscillatory expansion of a cylindrical plasma layer into vacuum is investigated analytically by solving the fluid equations of the electrons and ions together with the Maxwell's equations. For the problem considered, it is found that the asymmetrical flow components are strongly affected by the symmetrical components, but not the vice versa.

Asymmetric growth of root epidermal cells is related to the differentiation of root hair cells in Hordeum vulgare (L.)

The root epidermis of most vascular plants harbours two cell types, namely trichoblasts (capable of producing a root hair) and atrichoblasts. Here, in vivo analysis, confocal laser-scanning microscopy, transmission electron microscopy, histological analysis, and three-dimensional reconstruction were used to characterize the cell types present in the barley root epidermis and their distribution in the tissue. Both trichoblasts and atrichoblasts were present in the wild-type cultivars and could be distinguished from one another at an early stage. Trichoblast/atrichoblast differentiation depended on asymmetric cell expansion after a period of symmetrical cell division. After asymmetric growth, only the shorter epidermal cells could produce root hairs, whereas the longer cells became atrichoblasts. Moreover, the root epidermis did not develop root hairs at all if the epidermal cells did not differentiate into two asymmetric cell types. The root hairless phenotype of bald root barley (brb) and root hairless 1.b (rhl1.b) mutants was caused by a mutation in a gene related to the asymmetric expansion of the root epidermal cells. Additionally, the results showed that the mechanism of trichoblast/atrichoblast differentiation is not evolutionally conserved across the subfamilies of the Poaceae; in the Pooideae subfamily, both asymmetric division and asymmetric cell expansion have been observed.

A Simple Method to Treat Asymmetric Expansions in Three-Segment Surgically Assisted Rapid Maxillary Expansion

Surgically assisted rapid maxillary expansion (SARME) is a well-documented and established procedure indicated to treat maxillary transverse deficiencies in the adult patient. Currently, the most popular SARME technique consists of performing a Le Fort I osteotomy without downfracture and a midline osteotomy that splits the maxilla into 2 halves between the central incisors. It is supposed that the 2 halves expand equally during the activation phase. However, after completion of the osteotomies, the expander is supported by only mobile segments; thus, if 1 side remains more resistant than the other, the less resistant side expands more than the other, resulting in asymmetric expansion of the maxilla. When this complication occurs in SARME, an open revision surgery is necessary to remove bone interferences that prevent bone movement on the resistant segment or to create resistance on the other half. An alternative SARME technique consists of performing an osteotomy above the maxillary apical roots, similar to the Le Fort I osteotomy, and bilateral transalveolar osteotomies between the lateral incisors and canines, dividing the maxilla into 3 segments: a central fixed segment containing the incisors and 2 lateral segments that are expanded. Some advantages of 3-segment SARME have been described, such as a less esthetic compromise resulting from the midline diastema, less midline dental papilla compromise, preservation of the nasopalatine bundle, and greater acceptance of the procedure. This article describes another advantage of 3-segment SARME: the possibility to treat asymmetric expansions of the maxilla with an easy and conservative technique.

High-Resolution Ultrasound as an Effective and Practical Tool to Analyze Eyebrow Profile Expansion in Thyroid-Associated Periorbitopathy

Clinical, radiographic, and molecular studies have shown that patients with thyroid-associated orbitopathy exhibit volumetric expansion of eyebrow tissues. This clinicopathologic entity has been termed thyroid-associated periorbitopathy. The goal of this study was to determine whether high-resolution ultrasonography could be used to reliably quantify thyroid-associated periorbitopathy. Institutional review board approval was obtained. The internal case-control study consisted of 12 subjects with unilateral-asymmetric thyroid-associated orbitopathy. High-resolution ultrasonography using a 15-MHz probe (Logiq p6) was performed by a single operator. Measurements were obtained 0.5 cm cephalad to the superior orbital rim at the midpupillary sagittal level. For each subject and tissue layer thickness (total tissue, dermis fat, retro-orbicularis oculi fat), the measured values on the less affected side were subtracted from those on the more severely diseased side. Summary statistics were used to analyze results. High-resolution ultrasonography effectively demonstrated asymmetric expansion of total eyebrow tissue (p < 0.0001) and retro-orbicularis oculi fat (p = 0.0003). No significant difference in dermis fat thickness was found between the 2 sides (p = 0.2). Hertel exophthalmometry measurements were statistically different between the 2 sides (p = 0.002). This study demonstrates that high-resolution ultrasonography independently confirms previously published studies of retro-orbicularis oculi fat expansion in patients with thyroid-associated orbitopathy. Compared with CT, MRI, and tissue biopsy, high-resolution ultrasonography is a more practical and cost-effective way to quantify and track thyroid-associated periorbitopathy over time. With its potential for real-time tissue assessment, high-resolution ultrasonography may be best suited for future studies of the dynamic relationship between globe and periorbital structures.

Impact of Kissing Balloon Inflation on the Main Vessel Stent Volume, Area, and Symmetry After Side-Branch Dilation in Patients With Coronary Bifurcation Lesions: A Serial Volumetric Intravascular Ultrasound Study

Intravascular ultrasound (IVUS) was performed to investigate the impact of kissing balloon inflation (KBI) on the main vessel (MV) stent volume, area, and symmetry after side-branch (SB) dilation in patients with coronary bifurcation lesions (CBL). It remains controversial whether KBI would restore the MV stent area and symmetry loss after SB dilation. A total of 88 serial IVUS examinations of the MV were performed after MV angioplasty, MV stenting, SB dilation, and KBI in 22 patients with CBL. The MV stent was divided into proximal, bifurcation, and distal segments; the stent volume index (SVI), minimal stent area (MSA), stent symmetry index (SSI), and external elastic membrane (EEM) volume index were measured in 198 stent segments and compared after MV stenting, SB dilation, and KBI. In the bifurcation segment, SVI, MSA, and SSI were significantly smaller after SB dilation than after MV stenting and KBI (SVI was 6.10 ± 1.50 mm(3)/mm vs. 6.68 ± 1.60 mm(3)/mm and 6.57 ± 1.60 mm(3)/mm, respectively, p < 0.05; MSA was 5.15 ± 1.30 mm(2) vs. 6.08 ± 1.40 mm(2) and 5.86 ± 1.50 mm(2), respectively, p < 0.05; and SSI was 0.78 ± 0.02 mm(2) vs. 0.87 ± 0.03 mm(2) and 0.84 ± 0.03 mm(2), respectively, p < 0.05). KBI restored the MV SVI, MSA, and SSI after SB dilation. In the proximal segment, SVI, MSA, and EEM volume index were significantly larger, but SSI was smaller after KBI than after MV stenting and SB dilation. In the distal segment, neither SB dilation nor KBI had a significant impact on the MV stent volume or symmetry. This is the first comprehensive volumetric IVUS analysis of CBL, to our knowledge, demonstrating that KBI restores the MV stent volume, area, and symmetry loss after SB dilation in the bifurcation segment, and induces asymmetric stent expansion in the proximal segment.

Dynamics of laser induced micro-shock waves and hot core plasma in quiescent air

AbstractWe present our results on spatio-temporal evolution of laser plasma produced shockwaves (SWs) and hot core plasma (HCP) created by focused second harmonic (532 nm, 7 ns) of Nd-YAG laser in quiescent atmospheric air at f/#10 focusing geometry. Time resolved shadowgraphs imaged with the help of an ICCD camera with 1.5 ns temporal resolution revealed the presence of two co-existing sources simultaneously generating SWs. Each of the two sources independently led to a spherical SW following Sedov-Taylor theory along the laser propagation direction with a maximum velocity of 7.4 km/s and pressure of 57 MPa. While the interaction of SWs from the two sources led to a planar SW in the direction normal to the laser propagation direction. The SW detaches from the HCP and starts expanding into the ambient air at around 3 µs indicating the onset of asymmetric expansion of the HCP along the z-axis. The asymmetric expansion is observed till 10 µs beyond which the SW leaves the field of view followed by a deformation of the irradiated region in the XY-plane due to the penetration of surrounding colder air in to the HCP. The deformation in the XY-plane lasts till 600 µs. The dynamics of rapidly expanding HCP is observed to be analogous to that of cavitation bubble dynamics in fluids.

Asymmetric radial expansion and contraction of rat carotid artery observed using a high-resolution ultrasound imaging system

The geometry of carotid artery bifurcation is of high clinical interest because it determines the characteristics of blood flow that is closely related to the formation and development of atherosclerotic plaque. However, information on the dynamic changes in the vessel wall of carotid artery bifurcation during a pulsatile cycle is limited. This pilot study investigated the cyclic changes in carotid artery geometry caused by blood flow pulsation in rats. A high-resolution ultrasound imaging system with a broadband scanhead centered at 40MHz was used to obtain longitudinal images of the rat carotid artery. A high frame rate retrospective B-scan imaging technique based on the use of electrocardiogram to trigger signal acquisition was used to examine precisely the fast arterial wall motion. Two-dimensional geometry data obtained from nine rats showed that the rat carotid artery asymmetrically contracts and dilates during each cardiac cycle. Systolic/diastolic vessel diameters near the upstream and downstream regions from the bifurcation were 0.976±0.011/0.825±0.015mm and 0.766±0.015/0.650±0.016mm, respectively. Their posterior/anterior wall displacement ratios in the radial direction were 41.0±14.9% and 2.9±1.6%, respectively. These results indicate that in the vicinity of bifurcation, the carotid artery favorably expands to the anterior side during the systolic phase. This phenomenon was observed to be more prominent in the downstream region near the bifurcation. The cyclic variation pattern in wall movement varies depending on the measurement site, which shows different patterns at far upstream and downstream of the bifurcation. The asymmetric radial expansion and contraction of the rat carotid artery observed in this study may be useful in studying the hemodynamic etiology of cardiovascular diseases because the pulsatile changes in vessel geometry may affect the local hemodynamics that determines the spatial distribution of wall shear stress, one of important cardiovascular risk factors. Further systematic study is needed to clarify the effects of wall elasticity, branch angle and vessel diameter ratio on the asymmetric wall motion of carotid artery bifurcation.

ChemInform Abstract: A Catalytic Asymmetric Ring‐Expansion Reaction of Isatins and α‐Alkyl‐α‐diazoesters. Highly Efficient Synthesis of Functionalized 2‐Quinolone Derivatives.

Asymmetric expansion: A catalytic asymmetric ring-expansion reaction of the title compounds occurs in the presence of a Sc(OTf)(3) catalyst bearing an N,N'-dioxide-based ligand. Highly functionalized 2-quinolone derivatives containing a chiral C4-quaternary stereocenter were obtained in high yields and high levels of selectivity under mild reaction conditions (see scheme; Tf=trifluoromethanesulfonyl).

Intrafraction Bladder Motion in Radiation Therapy Estimated From Pretreatment and Posttreatment Volumetric Imaging

The use of image guidance protocols using soft tissue anatomy identification before treatment can reduce interfractional variation. This makes intrafraction clinical target volume (CTV) to planning target volume (PTV) changes more important, including those resulting from intrafraction bladder filling and motion. The purpose of this study was to investigate the required intrafraction margins for soft tissue image guidance from pretreatment and posttreatment volumetric imaging. Fifty patients with muscle-invasive bladder cancer (T2-T4) underwent an adaptive radiation therapy protocol using daily pretreatment cone beam computed tomography (CBCT) with weekly posttreatment CBCT. A total of 235 pairs of pretreatment and posttreatment CBCT images were retrospectively contoured by a single radiation oncologist (CBCT-CTV). The maximum bladder displacement was measured according to the patient's bony pelvis movement during treatment, intrafraction bladder filling, and bladder centroid motion. The mean time between pretreatment and posttreatment CBCT was 13 minutes, 52 seconds (range, 7 min 52 sec to 30 min 56 sec). Taking into account patient motion, bladder centroid motion, and bladder filling, the required margins to cover intrafraction changes from pretreatment to posttreatment in the superior, inferior, right, left, anterior, and posterior were 1.25 cm (range, 1.19-1.50 cm), 0.67 cm (range, 0.58-1.12 cm), 0.74 cm (range, 0.59-0.94 cm), 0.73 cm (range, 0.51-1.00 cm), 1.20 cm (range, 0.85-1.32 cm), and 0.86 cm (range, 0.73-0.99), respectively. Small bladders on pretreatment imaging had relatively the largest increase in pretreatment to posttreatment volume. Intrafraction motion of the bladder based on pretreatment and posttreatment bladder imaging can be significant particularly in the anterior and superior directions. Patient motion, bladder centroid motion, and bladder filling all contribute to changes between pretreatment and posttreatment imaging. Asymmetric expansion of CTV to PTV should be considered. Care is required in using image-guided radiation therapy protocols that reduce CTV to PTV margins based only on daily pretreatment soft tissue position.

Shockwave and cavitation bubble dynamics of atmospheric air

The generation and evolution of laser induced shock waves (SWs) and the hot core plasma (HCP) created by focusing 7 ns, 532 nm laser pulses in ambient air is studied using time resolved shadowgraphic imaging technique. The dynamics of rapidly expanding plasma releasing SWs into the ambient atmosphere were studied for time delays ranging from nanoseconds to milliseconds with ns temporal resolution. The SW is observed to get detached from expanding HCP at around 3μs. Though the SWs were found to expand spherically following the Sedov-Taylor theory, the rapidly expanding HCP shows asymmetric expansion during both the expansion and cooling phase similar to that of inertial cavitation bubble (CB) dynamics. The asymmetric expansion of HCP leads to oscillation of the plasma boundary, eventually leading to collapse by forming vortices formed by the interaction of ambient air.