Inflation Technique Research Articles

Packing stability for symplectic $4$-manifolds

AbstractThe packing stability in symplectic geometry was first noticed byBiran [Bir97]: the symplectic obstructions to embed several balls into amanifold disappear when their size is small enough. This phenomenonis known to hold for all closed manifolds with rational symplectic class(see [Bir99] for the 4-dimensional case, and [BH11, BH13] for higherdimensions), as well as for all ellipsoids [BH13].In this note, we show that packing stability holds for all closed, andseveral open, symplectic 4-manifolds. 1 Introduction In [Bir97, Bir99], Biran discovered the packing stability phenomenon: insome symplectic 4-manifolds, the symplectic obstructions to pack Nidenti-cal balls disappear when Nbecomes large enough. He later generalized thisresult to every closed symplectic 4-manifold with rational symplectic class([ω] ∈ H 2 (M,Q)).In this paper we generalize these results in several directions, by applyingthe singular inflation technique developed in [Ops13b, MO13]. We generalizeBiran’s packing stability to all symplectic 4-manifolds, and also to a class ofopensymplectic 4-manifolds includingellipsoids anddomainswe call pseudo-balls. For these manifolds, we establish not just packing stability but strongpacking stability, which we define now. The definition is in the spirit ofBiran’s first results on the subject [Bir97]. Throughout B(λ) will denote anopen ball of capacity λ(see Definition 1.3) and we will write U

Neural substrates in secondary somatosensory area for the perception of different tactile sensations

ABSTRACTThis functional magnetic resonance imaging (fMRI) study investigated the secondary somatosensory area (SII) in humans, especially regarding the presence of distinctive spatial arrangements of neural subunits responding to different types of tactile stimuli. Ten healthy volunteers received four different sensory stimuli on the palmar side of the right hand—vibrotactile, pressure, warmth, and coolness. Based on group‐level analysis of the fMRI data, all four of the somatosensory stimuli resulted in activations in the bilateral SII and insula as well as the SI contralateral to the stimulation. The spatial distribution of neural activations corresponding to each stimulus, as examined by cortical inflation technique, revealed significant overlaps, but also showed the differences in terms of its overall topology. The local maxima of the activation within the SII, corresponding to these stimuli, manifested distinctive spatial location. These results suggest that differential networks of the SII subregions are involved in the processing of the different nature of the tactile stimuli, while sharing common regions in the parietal operculum.

Plastic Biliary Stent Migration During Multiple Stents Placement and Successful Endoscopic Removal Using Intra-Stent Balloon Inflation Technique: A Case Report and Literature Review

Patient: Male, 77Final Diagnosis: Biliary neoplasmSymptoms: —Medication: —Clinical Procedure: Biliary stent removal using intra-stent balloon inflation techniqueextractionSpecialty: Gastroenterology and HepatologyObjective:Diagnostic/therapeutic accidentsBackground:Late migration of a plastic biliary stent after endoscopic placement is a well known complication, but there is little information regarding migration of a plastic stent during multiple stents placement.Case Report:A white man was hospitalized for severe jaundice due to neoplastic hilar stenosis. Surgical eligibility appeared unclear on admission and endoscopy was carried out, but the first stent migrated proximally at the time of second stent insertion. After failed attempts with various devices, the migrated stent was removed successfully through cannulation with a dilation balloon.Conclusions:The migration of a plastic biliary stent during multiple stents placement is a possible complication. In this context, extraction can be very complicated. In our patient, cannulation of a stent with a dilation balloon was the only effective method.

Ultra-thin graphene–polymer heterostructure membranes

The fabrication of arrays of ultra-thin conductive membranes remains a major challenge in realising large-scale micro/nano-electromechanical systems (MEMS/NEMS), since processing-stress and stiction issues limit the precision and yield in assembling suspended structures. We present the fabrication and mechanical characterisation of a suspended graphene-polymer heterostructure membrane that aims to tackle the prevailing challenge of constructing high yield membranes with minimal compromise to the mechanical properties of graphene. The fabrication method enables suspended membrane structures that can be multiplexed over wafer-scales with 100% yield. We apply a micro-blister inflation technique to measure the in-plane elastic modulus of pure graphene and of heterostructure membranes with a thickness of 18 nm to 235 nm, which ranges from the 2-dimensional (2d) modulus of bare graphene at 173 ± 55 N m-1 to the bulk elastic modulus of the polymer (Parylene-C) as 3.6 ± 0.5 GPa as a function of film thickness. Different ratios of graphene to polymer thickness yield different deflection mechanisms and adhesion and delamination effects which are consistent with the transition from a membrane to a plate model. This system reveals the ability to precisely tune the mechanical properties of ultra-thin conductive membranes according to their applications.

Ensemble Filtering and Low-Resolution Model Error: Covariance Inflation, Stochastic Parameterization, and Model Numerics

Abstract The use of under-resolved models in ensemble data assimilation schemes leads to two kinds of model errors: truncation errors associated with discretization of the large-scale dynamics and errors associated with interactions with subgrid scales. Multiplicative and additive covariance inflation can be used to account for model errors in ensemble Kalman filters, but they do not reduce the model error. Truncation errors can be reduced by increasing the accuracy of the numerical discretization of the large-scale dynamics, and subgrid-scale parameterizations can reduce errors associated with subgrid-scale interactions. Stochastic subgrid-scale parameterizations both reduce the model error and inflate the ensemble spread, so their effectiveness in ensemble assimilation schemes can be gauged by comparing with covariance inflation techniques. The effects of covariance inflation, stochastic parameterizations, and model numerics in two-layer periodic quasigeostrophic turbulence are compared on an f plane and on a β plane. The stochastic backscatter schemes used here model backscatter in the inverse cascade regime of quasigeostrophic turbulence, as appropriate to eddy-permitting ocean models. Covariance inflation improves the performance of a benchmark model with no parameterizations and second-order numerics. Fourth-order spatial discretization and the stochastic parameterizations, alone and in combination, are superior to covariance inflation. In these experiments fourth-order numerics and stochastic parameterizations lead to similar levels of improvement in filter performance even though the climatology of models without stochastic parameterizations is poor.

Characterization of Polymeric Membranes Under Large Deformations Using Fluid-Structure Coupling

The mechanical properties of Ogden material under biaxial deformation are obtained by using the bubble inflation technique. First, pressure inside the bubble and height at the hemispheric pole are recorded during bubble inflation experiment. Thereafter, Ogden's theory of hyperelasticity is employed to define the constitutive model of flat circular thermoplastic membranes (CTPMs) and nonlinear equilibrium equations of the inflation process are solved using finite difference method with deferred corrections. As a last step, a neuronal algorithm artificial neural network (ANN) model is employed to minimize the difference between calculated and measured parameters to determine material constants for Ogden model. This technique was successfully implemented for acrylonitrile-butadiene-styrene (ABS), at typical thermoforming temperatures, 145°C. When solving for the bubble inflation, the recorded pressure is applied uniformly on the structure. During the process inflation, the pressure is not uniform inside the bubble, thus full gas dynamic equations need to be solved to get the appropriate nonuniform pressure to be applied on the structure. In order to simulate the inflation process accurately, computational fluid dynamics in a moving fluid domain as well as fluid structure interaction (FSI) algorithms need to be performed for accurate pressure prediction and fluid structure interface coupling. Fluid structure interaction solver is then required to couple the dynamic of the inflated gas to structure motion. Recent development has been performed for the simulation of gas dynamic in a moving domain using arbitrary Lagrangian Eulerian (ALE) techniques.

Endotracheal Tube Cuff Pressure Assessment: Education May Improve but not Guarantee the Safety of Palpation Technique.

Background:Endotracheal Tube Cuff Pressure (ETCP) should be kept in the range of 20 - 30 cm H2O. Earlier studies suggested that ETCP assessment by palpation of pilot balloon results in overinflation or underinflation and subsequent complications such as tracheal wall damage and aspiration.Objectives:The current study aimed to evaluate the effect of an in vitro educational program on the ability of anesthesia personnel to inflate Endotracheal Tube Cuffs (ETT) within safe pressure limits.Patients and Methods:The survey included two series of blinded ETCP measurements in intubated patients before and two weeks after an in vitro educational intervention. The in vitro educational program included two separate trials. The anesthesia personnel were asked to inflate an ETT cuff inserted in a tracheal model using their usual inflation technique. In the same session, six ETTs at different pressure levels were examined by the participants and their estimation of ETCP was recorded. After the in vitro assessment, the participants were informed about the actual pressure of the in vitro ETCPs and were allowed to train their fingers by in vitro pilot balloon palpation with validated manometer measurements.Results:The mean ETCP after the in vitro survey was significantly lower than the mean ETCP before the intervention (45 ± 13 vs. 51 ± 15 cm H2O, P = 0.002). The rate of measurements within the safe pressure limits significantly improved after the in vitro education (24.2% vs. 39.7%, P = 0.002).Conclusions:Implementing educational programs with the introduction of estimation techniques besides the use of manometer as a standard intraoperative monitoring will improve the safety of the practice.

Study of the elastic behaviour of wood–plastic composites at cold temperatures using artificial neural networks

Using wood as natural reinforcement in composite materials, instead of mineral reinforcements, has several advantages such as low density, low cost, and less abrasive finish. The natural reinforcements also are non-toxic and recyclable. The general aim of this work is to provide a novel approach in material characterization and, in the future, to apply this method to investigate the elastic, hyperelastic, and viscoelastic behaviour of wood–plastic composites (WPCs) for potential applications in several industries. In this research, the bubble inflation technique is used to study the elastic behaviour of bio-composite materials at cold temperatures. The results of experiments with high-density polyethylene (HDPE) and WPC membranes with 30 and 60 wt% of wood fibre, under the combined effect of temperature and pressure, are presented. A unique approach that uses the results of computer simulations in Abaqus, a finite element package, combined with artificial neural networks is applied in order to find the optimum material constants for different materials at cold temperatures. The values of Young’s modulus for HDPE and WPCs with 30 and 60 wt% of wood fibre are reported at different temperatures.

Symplectic packings in dimension $4$ and singular curves

The main goal of this paper is to give constructive proofs of several existence results for symplectic embeddings. The strong relation between symplectic packings and singular symplectic curves, which can be derived from McDuff’s inflations on the blow-ups, is revisited through a new inflation technique that lives at the level of the manifold. As an application, we explain constructions of maximal symplectic packings of P by 6, 7 or 8 balls.

Transgastric endoscopic gastrojejunostomy using holing followed by interrupted suture technique in a porcine model.

To demonstrate the feasibility and reproducibility of a pure natural orifice transluminal endoscopic surgery (NOTES) gastrojejunostomy using holing followed by interrupted suture technique using a single endoloop matched with a pair of clips in a non-survival porcine model. NOTES gastrojejunostomy was performed on three female domestic pigs as follows: Gastrostomy, selection and retrieval of a free-floating loop of the small bowel into the stomach pouch, hold and exposure of the loop in the gastric cavity using a submucosal inflation technique, execution of a gastro-jejunal mucosal-seromuscular layer approximation using holing followed by interrupted suture technique with endoloop/clips, and full-thickness incision of the loop with a Dual knife. Pure NOTES side-to-side gastrojejunostomy was successfully performed in all three animals. No leakage was identified via methylene blue evaluation following surgery. This novel technique for preforming a gastrointestinal anastomosis exclusively by NOTES is technically feasible and reproducible in an animal model but warrants further improvement.

Development of an Improved Rabbit Model of Spinal Cord Compression by Embolectomy Catheter

The aim of this experimental study was to evaluate the efficacy of epidural balloon inflation into the unroofed spinal cord for the creation of a experimental spinal cord injury model in rabbits. Ten New Zealand white rabbits were used for this study. Before operation and after anasthesia with 60 mg/kg ketamine and 6 mg/kg xylazine. A midline skin incision was done on the lumbar skin at the level of L1-L4 lumbar vertebrae. Paravertebral muscles were bluntly dissected bilaterally. A microhemilaminotomy was done in the right L3 lamina close to the midline. An arteial embolectomy catheter was inserted into the spinal column between the bone and dura mater to the level of L1-L2 intervertebral space. The microballoon was gradually inflated by using a volume-controlled microballoon inflation syringe over a period of 3 minutes. The microballoon was deflated 8 minutes later and removed completely from the epidural space. All rabbits were paraplegic after the operation. In conclusion, this experimental study demonstrated that the microballoon inflation technique is a very successful method for the evaluation of spinal cord injury in rabbits. Unroofing of the spinal column is extremely important because decompression may be an effective treatment in spinal cord injury. A suitable spinal injury model was created, that is minimally invasive, uniform and easily reproducible.

Study of Glove Perforation during Hip Replacement Arthroplasty: Its Frequency, Location, and Timing.

Objective. The aim of the study was to evaluate the location, timing, and frequency of glove perforation during hip replacement arthroplasty. Methods. Gloves worn by surgical team members in 19 primary hip replacement arthroplasties were assessed. The study was of a single gloving system. All the used gloves were collected at the end of the surgery and assessed visually and by using water inflation technique. Relevant data were collected at the time of surgery. Results. A total of one hundred and ninety-one surgical gloves were evaluated. Twenty-three glove perforations were noted in nineteen of the operations. Of these perforations 14 belonged to gloves worn by surgeon and first assistant (60.1%). Glove perforation in thumb, index finger, and palm was more common. More perforation occurred in the gloves worn in nondominant hand (52%) but was insignificant. Conclusion. Glove perforation in surgeries such as total hip arthroplasty is not uncommon. In this study of single gloving system glove perforation rate was 12.04%, whereas literature reports of glove perforation rate as low as 3.3% in elective orthopedic surgeries with double gloving system. As such emphasis should be given to wear double pair of gloves wherever this practice is uncommon.

An efficient method for obtaining the hyperelastic properties of filled elastomers in finite strain applications

An efficient methodology for obtaining hyperelastic material parameters for filled elastomers utilizing unloading curves in uniaxial tension, pure shear and the inflation of a rubber membrane is presented. Experimental results from biaxial extension are crucial when fitting hyperelastic material parameters, and the bubble inflation technique is an excellent method of obtaining this data when specialized test equipment is unavailable. Moreover, filled elastomers have considerable hysteresis, and the hysteresis grows with increasing strain amplitudes. Therefore, the loading curve is in general comprised of both elastic and inelastic contributions, even at very low strain rates. Consequently, it is deemed more accurate to use experimental data from the unloading curve to describe the elastic behavior of the material. The presented methodology enables obtainment of parameters related to both the first and second strain invariant, which is required for a good fit between measurement and simulation results. Finally, it is essential that a chosen material model is accurate in all deformation modes when designing components subjected to a complex, multi-axial load history. An accurate material model enables more concepts and geometries of a component to be studied before a physical prototype is available.

Derivation of recruitment function from the pressure–volume curve in an acute lung injury model

Lung volume changes involve the recruitment of collapsed alveoli and the expansion of already opened alveoli. This study aimed to determine the alveolar recruitment function by using a mathematical model from a pressure–volume curve (P–V curve). We assumed a lung model as VL=R(P)V0f(P), where R recruitment function is the fraction of recruited alveoli, V0 is the resting lung volume at FRC of a fully recruited lung, and f(P) corresponds to the normalized compliance function of the lungs open to ventilation. Seven white rabbits were subjected to saline-lavage lung injury, and P–V curves were calculated using the slow inflation technique. We obtained the P–R curve from the P–V curve, and two curves were differently shaped after lung injury. We concluded that the recruitment function was obtained from the P–V curve and that the P–R curve estimated the recruitment and derecruitment status.

Tracheostomy: epidemiology, indications, timing, technique, and outcomes.

Tracheostomy is a common procedure performed in critically ill patients requiring prolonged mechanical ventilation for acute respiratory failure and for airway issues. The ideal timing (early vs late) and techniques (percutaneous dilatational, other new percutaneous techniques, open surgical) for tracheostomy have been topics of considerable debate. In this review, we address general issues regarding tracheostomy (epidemiology, indications, and outcomes) and specifically review the literature regarding appropriate timing of tracheostomy tube placement. Based on evidence from 2 recent large randomized trials, it is reasonable to wait at least 10 d to be certain that a patient has an ongoing need for mechanical ventilation before consideration of tracheostomy. Percutaneous tracheostomy with flexible bronchoscopy guidance is recommended, and optimal percutaneous techniques, indications, and contraindications and results in high-risk patients (coagulopathy, thrombocytopenia, obesity) are reviewed. Additional issues related to tracheostomy diagnosis-related groups, charges, and procedural costs are reviewed. New advances regarding tracheostomy include the use of real-time ultrasound guidance for percutaneous tracheostomy in high-risk patients. New tracheostomy tubes (tapered with low-profile cuffs that fit better on the tapered dilators, longer percutaneous tracheostomy tubes) are discussed for optimal use with percutaneous dilatational tracheostomy. Two new percutaneous techniques, a balloon inflation technique (Dolphin) and the PercuTwist procedure, are reviewed. The efficacy of tracheostomy teams and tracheostomy hospital services with standardized protocols for tracheostomy insertion and care has been associated with improved outcomes. Finally, the UK National Tracheostomy Safety Project developed standardized resources for education of both health care providers and patients, including emergency algorithms for tracheostomy incidents, and serves as an excellent educational resource in this important area.

Radiation belt data assimilation of a moderate storm event using a magnetic field configuration from the physics-based RAM-SCB model

Abstract. Data assimilation using Kalman filters provides an effective way of understanding both spatial and temporal variations in the outer electron radiation belt. Data assimilation is the combination of in situ observations and physical models, using appropriate error statistics to approximate the uncertainties in both the data and the model. The global magnetic field configuration is one essential element in determining the adiabatic invariants for the phase space density (PSD) data used for the radiation belt data assimilation. The lack of a suitable global magnetic field model with high accuracy is still a long-lasting problem. This paper employs a physics-based magnetic field configuration for the first time in a radiation belt data assimilation study for a moderate storm event on 19 December 2002. The magnetic field used in our study is the magnetically self-consistent inner magnetosphere model RAM-SCB, developed at Los Alamos National Laboratory (LANL). Furthermore, we apply a cubic spline interpolation method in converting the differential flux measurements within the energy spectrum, to obtain a more accurate PSD input for the data assimilation than the commonly used linear interpolation approach. Finally, the assimilation is done using an ensemble Kalman filter (EnKF), with a localized adaptive inflation (LAI) technique to appropriately account for model errors in the assimilation and improve the performance of the Kalman filter. The assimilative results are compared with results from another assimilation experiment using the Tsyganenko 2001S (T01S) magnetic field model, to examine the dependence on a magnetic field model. Results indicate that the data assimilations using different magnetic field models capture similar features in the radiation belt dynamics, including the temporal evolution of the electron PSD during a storm and the location of the PSD peak. The assimilated solution predicts the energy differential flux to a relatively good degree when compared with independent LANL-GEO in situ observations. A closer examination suggests that for the chosen storm event, the assimilation using the RAM-SCB predicts a better flux at most energy levels during storm recovery phase but is slightly worse in the storm main phase than the assimilation using the T01S model.

Optimal lung inflation techniques in a rat lung transplantation model: a revisit.

Most of the experimental work assessing optimal lung inflation during lung graft preservation was performed in the late 1990s. Since that time, lung preservation before transplantation has been more standardized, and the optimal lung inflation techniques used during lung preservation in the current clinical setting remain undefined. Nonetheless, lung inflation during storage may play a pivotal role in optimal lung preservation. Lewis rat lungs were perfused with and stored in cold, low-potassium dextran solution (Perfadex, Vitrolife, Göteborg, Sweden) for 6 hours at different levels of lung inflation (25, 50, 75, or 100% of vital capacity [VC]). Orthotopic left lung transplantation using cuff techniques was performed in syngeneic Lewis rats. Posttransplant allograft function, expression of proinflammatory mediators, and expression of lung surfactants were evaluated. Lungs inflated to 75 or 100% VC showed a significantly better oxygenation in blood gas analysis than lungs inflated to 25 or 50% VC. The levels of mRNAs for tumor necrosis factor-α, pro-interleukin-1β, intracellular adhesion molecule 1 were attenuated in lungs inflated to 75 or 100% VC as compared with deflated lungs, suggesting reduced ischemia/reperfusion injury. In addition, transmission electron microscopy demonstrated better preserved lung surfactants in the alveolar space in the lungs inflated to 75 or 100% VC. Inflating lungs to 75 or 100% VC during preservation may be beneficial and result in better posttransplant allograft function through attenuated reperfusion injury and better preserved lung surfactants.

Comparison of static mesoscale background‐error covariances estimated by three different ensemble data assimilation techniques

AbstractThree ensemble‐based analysis‐error representation techniques are applied and compared with the aim of simulating background errors of the mesoscale limited‐area model (LAM) Aire Limitée Adaptation Dynamique Développement International (ALADIN) and thus computing appropriate mesoscale static background‐error covariances for its three‐dimensional variational (3DVAR) data assimilation system. Real data assimilation experiments are performed for the simulation of the background errors, where uncertainties of the initial conditions and lateral boundary conditions are represented, while model errors are not accounted for. The three analysis error‐simulation techniques compared are as follows: (i) the downscaling of the analysis error represented by the stochastic ensemble data assimilation (EDA) system of a global model (DSC EDA); (ii) the representation of the analysis error by a LAM stochastic ensemble data assimilation (LAM EDA) system; and (iii) the representation of the analysis error by a LAM ensemble transform Kalman filter (LAM ETKF) system. Spectral diagnostics have been developed in the study, allowing an examination of the simulated background errors at different spatial scales. It is shown that LAM EDA provides more realistic simulated background errors than DSC EDA, particularly at mesoscales. This is also partly the case for LAM ETKF at mesoscales (although to a lesser extent than for LAM EDA). The error variance is underestimated by LAM ETKF, which suggests that the applied inflation technique could be improved. Analysis and forecast impact studies using background‐error covariance matrices based on the DSC EDA and LAM EDA error samples confirm the superiority of the latter simulation technique.

A dome-shaped piezoelectric tactile sensor arrays fabricated by an air inflation technique

In this paper, we propose and demonstrate a dome-shaped piezoelectric tactile sensor fabricated by an inflation technique. The sensor module consists of a 4×4 dome-shaped cell, an Ag electrode layer, a polyimide film for electrode protection, a bump structure, and a PDMS diaphragm for supporting the sensor. The piezoelectric sensor can convert an applied contact force into an electrical signal by using the piezoelectric effect. A normal force applied to the sensor deforms the cell, and consequently generates an output voltage proportional to the cell deformation. Therefore, by using a dome-shaped structure instead of the conventional flat structure, the tactile sensor can obtain high sensitivity. To make the dome-shaped PVDF film, a simple fabrication process based on an inflation technique for controlling the trapped air has been developed. The dome-shaped PVDF film was successfully fabricated, and then used as a sensing structure for a tactile sensor. In order to compare the sensitivity of the sensor, a flat tactile sensor was fabricated with the same design as the proposed sensor. The achieved sensitivities of the sensor are 6.028×10−3V/mN, 7.89×10−3V/mN, and 8.83×10−3V/mN, for the flat sensor and for two dome-shaped sensors (with h=0.5mm and 1.0mm), respectively. The sensitivity of the proposed device shows a maximum 46.4% greater than that of a conventional flat tactile sensor. Also, through measurements of frequency response and crosstalk, the proposed tactile sensor showed stable performance.

Incidence and predictors of difficult nasotracheal intubation with airway scope

PurposeThe airway scope (AWS) improves views of the larynx during orotracheal intubation. However, the role of the AWS in routine nasotracheal intubation has not been studied adequately.MethodsOne hundred and three patients undergoing dental and maxillofacial surgery that required general anesthesia and nasotracheal intubation were enrolled. The study was approved by our Institution Review Board, and written informed consent was obtained from all patients. We evaluated the success rate of AWS intubation and the incidence of difficult nasotracheal intubation using a modified intubation difficulty scale (IDS) to examine preoperative characteristics and intubation profiles. Categories were difficult intubation (IDS ≥5), mildly difficult (IDS = 1–4), and intubation without difficulty (IDS = 0). We also assessed the incidence of the use of Magill forceps or cuff inflation (the cuff of endotracheal tube is inflated with 10–15 ml air) to guide the endotracheal tube into the glottis.ResultsAWS nasotracheal intubation was 100 % successful. The cuff inflation technique was used in 37 patients. Neither Magill forceps nor other devices were needed for any patient during AWS use. The incidence of difficult nasotracheal intubation was 10 % (n = 10). Of the patients, 61 % (n = 63) had mildly difficult intubation and 29 % (n = 30) had no difficulty. Patients with difficult intubation were more likely to be male and to have a larger tongue and a higher Cormack grade than in the other two groups. Complications, involving minor soft tissue injury, were observed in only 1 patient (1 %).ConclusionThe AWS achieves a high success rate for nasotracheal intubation with cuff inflation in patients undergoing dental and maxillofacial surgery.