Larger Initial Diameter Research Articles

Standardization and optimization of the hiPSC-based PluriLum assay for detection of embryonic and developmental toxicants.

New approach methodologies (NAMs) for predicting embryotoxicity and developmental toxicity are urgently needed for generating human relevant data, while reducing turnover time and costs, and alleviating ethical concerns related to the use of animal models. We have previously developed the PluriLum assay, a NKX2.5-reporter gene 3D model using human-induced pluripotent stem cells (hiPSCs) that are genetically modified to enable the assessment of adverse effects of chemicals on the early-stage embryo. Aiming at improving the predictive value of the PluriLum assay for future screening purposes, we sought to introduce standardization steps to the protocol, improving the overall robustness of the PluriLum assay, as well as a shortening of the assay protocol. First, we showed that the initial size of embryoid bodies (EBs) is crucial for a proper differentiation into cardiomyocytes and overall reproducibility of the assay. When the starting diameter of the EBs exceeds 500 µm, robust differentiation can be anticipated. In terms of reproducibility, exposure to the fungicide epoxiconazole at smaller initial diameters resulted in a larger variation of the derived data, compared to more reliable concentration-response curves obtained using spheroids with larger initialdiameters. We further investigated the ideal length of the differentiation protocol, resulting in a shortening of the PluriLum assay by 24 h to 7 days. Following exposure to the teratogens all-trans and 13-cis retinoic acid, both cardiomyocyte contraction and measurement of NKX2.5-derived luminescence were recorded with a similar or increased sensitivity after 6 days of differentiation when compared to the original 7 days. Finally, we have introduced an efficient step for enzymatic dissociation of the EBs at assay termination. This allows for an even splitting of the individual EBs and testing of additional endpoints other than the NKX2.5-luciferase reporter, which was demonstrated in this work by the simultaneous assessment of ATP levels. In conclusion, we have introduced standardizations and streamlined the PluriLum assay protocol to improve its suitability as a NAM for screening of a large number of chemicals for developmental toxicity testing.

Ultrasound-guided percutaneous thermal ablation of parotid tumors: experience from two-centers

Objective: To evaluate the efficacy and feasibility of ultrasound-guided percutaneous thermal ablation (TA) for treating benign parotid tumors. Methods: Patients with benign parotid tumors who underwent ultrasound-guided microwave ablation (MWA) or radiofrequency ablation (RFA) between January 2020 and March 2023 were included in this retrospective study. Change in tumor size (maximum diameter, tumor volume(V), volume reduction rate (VRR)) and cosmetic score (CS) were evaluated during a one-year follow-up period. We also recorded the incidence of any complications associated with TA. Results: A total of 23 patients (13 males and 10 females; median age 65 years, range 5–91 years) were included. The mean VRR at 1, 3, 6, and 12 months after TA was 37.03%±10.23%, 56.52%±8.76%, 82.28%±7.89%, and 89.39%±6.45%, respectively. Mean CS also changed from 3.39 ± 0.66 to 1.75 ± 0.93 (p < 0.001) by the end of follow-up time. Subgroup analysis showed that tumors with smaller initial maximum diameter had a faster CS reduction rate than those with larger initial diameter. The incidence of facial nerve dysfunction was 8.70%. Conclusion: Ultrasound-guided percutaneous TA is an effective and safe treatment option for patients with benign parotid tumors.

Computer-aided shape features extraction and regression models for predicting the ascending aortic aneurysm growth rate

Objective:ascending aortic aneurysm growth prediction is still challenging in clinics. In this study, we evaluate and compare the ability of local and global shape features to predict the ascending aortic aneurysm growth. Material and methods:70 patients with aneurysm, for which two 3D acquisitions were available, are included. Following segmentation, three local shape features are computed: (1) the ratio between maximum diameter and length of the ascending aorta centerline, (2) the ratio between the length of external and internal lines on the ascending aorta and (3) the tortuosity of the ascending tract. By exploiting longitudinal data, the aneurysm growth rate is derived. Using radial basis function mesh morphing, iso-topological surface meshes are created. Statistical shape analysis is performed through unsupervised principal component analysis (PCA) and supervised partial least squares (PLS). Two types of global shape features are identified: three PCA-derived and three PLS-based shape modes. Three regression models are set for growth prediction: two based on gaussian support vector machine using local and PCA-derived global shape features; the third is a PLS linear regression model based on the related global shape features. The prediction results are assessed and the aortic shapes most prone to growth are identified. Results:the prediction root mean square error from leave-one-out cross-validation is: 0.112 mm/month, 0.083 mm/month and 0.066 mm/month for local, PCA-based and PLS-derived shape features, respectively. Aneurysms close to the root with a large initial diameter report faster growth. Conclusion:global shape features might provide an important contribution for predicting the aneurysm growth.

Hydrodynamic analysis of the energy dissipation of droplets on vibrating superhydrophobic surfaces

In this paper, experimental and numerical methods are presented to describe the hydrodynamic process of the vibration-induced detachment of a droplet from a superhydrophobic surface. We conduct the investigation of the droplet dynamics under various vibration and impact parameters, from an energy conversion perspective. In particular, the energy dissipation that occurs following the droplet impact is analyzed quantitatively. We identify three viewpoints on vibration-induced droplets. Firstly, the phase angle is the dominant factor in characterizing the droplet morphology evolution and energy dissipation on a vibrating surface. The law governing the initial phase angle is affected by the vibration frequency, while the intensity is affected by the vibration amplitude. Secondly, the energy dissipation is positively correlated with the maximum spreading diameter and impact velocity. A larger initial diameter tends to produce a longer contact time. Finally, the central jet formation depends heavily on the upward velocity of the concave liquid, under the peculiar morphology of a vibration-induced droplet. For all these effects, up to 60% of the total energy is squandered during impact, while the surface energy remains almost constant. Much of the droplet's kinetic energy is lost in resisting the viscous force of the substrate.

Evaporation flow characteristics of respiratory droplets: Dynamic property under multifarious ambient conditions

This study numerically investigated the impact of ambient conditions on the evaporation process of full-range cough expelled droplets. The multi-component Eulerian-Lagrangian framework was adopted to simulate droplet evaporation within the inhomogeneous humidity fields. The results found that effect of ambient relative humidity (RH) on droplet evaporation was more pronounced than that of temperature. When the ambient relative humidity was higher than 40%RH, the evaporation of droplets with a diameter smaller than 100 μm would be significantly decelerated. Meanwhile, in normal indoor environments, 175μm could be a marginal diameter, in which droplets with larger initial diameters would probably not be fully evaporated before settling to the ground. Moreover, a novel cost-efficient approach, representing the instantaneous droplet diameter by functions of dt=φ(RH,t,T), was developed to fulfil the time-dependent dynamic size distributions of evaporated droplets under various ambient conditions directly from the data by this study. The implementation of this approach into User Defined Function (UDF) was demonstrated and it would significantly reduce the computational resource on simulating droplet-related scenarios as it does not require costly calculations on the evaporation processes of each droplet repeatedly in every simulation. This development is limited to cough droplets so far and further fulfilment on droplets database regarding other respiratory behaviours would be highly suggested.

Numerical study on the desorption processes of oil droplets inside oil-contaminated sand under cavitation micro-jets

The removal of the adsorbed oil droplet is critical to deoiling treatment of oil-bearing solid waste. Ultrasonic cavitation is regarded as an extremely useful method to assist the oil droplets desorption in the deoiling treatment. In this paper, the effects of cavitation micro-jets on the oil droplets desorption were studied. The adsorbed states of oil droplets in the oil-contaminated sand were investigated using a microscope. Three representative absorbed states of the oil droplets can be summarized as: (1) the individual oil droplet adsorbed on the particle surface (2) the clustered oil droplets adsorbed on the particle surface; (3) the oil droplet adsorbed in a gap between particles. The micro-jet generation during the bubble collapse near a rigid wall under different acoustic pressure amplitudes at an ultrasonic frequency of 20 kHz was investigated numerically. The desorption processes of the oil droplets at the three representative absorbed states under micro-jets were also simulated subsequently. The results showed that the acoustic pressure has a great influence on the velocity of micro-jet, and the initial diameter of cavitation bubbles is significant for the cross-sectional area of micro-jets. The wall jet caused by a micro-jet impacting on the solid wall is the most important factor for the removal of the absorbed oil droplets. The oil droplet is broken by the jet impinging, and then it breaks away from the solid wall due to the shear force generated by the wall jet. In addition to a higher sound pressure, the cavitation bubble at a larger initial diameter is more important for the desorption of the clustered oil droplets. Conversely, the micro-jet generated by the cavitation bubble at a smaller initial diameter (0.1 mm) is more appropriate for the desorption of the oil droplet in a narrow or sharp-angled gap.

Long-term follow-up of persistent pulmonary pure ground-glass nodules with deep learning-assisted nodule segmentation.

To investigate the natural history of persistent pulmonary pure ground-glass nodules (pGGNs) with deep learning-assisted nodule segmentation. Between January 2007 and October 2018, 110 pGGNs from 110 patients with 573 follow-up CT scans were included in this retrospective study. pGGN automatic segmentation was performed on initial and all follow-up CT scans using the Dr. Wise system based on convolution neural networks. Subsequently, pGGN diameter, density, volume, mass, volume doubling time (VDT), and mass doubling time (MDT) were calculated automatically. Enrolled pGGNs were categorized into growth, 52 (47.3%), and non-growth, 58 (52.7%), groups according to volume growth. Kaplan-Meier analyses with the log-rank test and Cox proportional hazards regression analysis were conducted to analyze the cumulative percentages of pGGN growth and identify risk factors for growth. The mean follow-up period of the enrolled pGGNs was 48.7 ± 23.8months. The median VDT of the 52 pGGNs having grown was 1448 (range, 339-8640) days, and their median MDT was 1332 (range, 290-38,912) days. The 12-month, 24.7-month, and 60.8-month cumulative percentages of pGGN growth were 10%, 25.5%, and 51.1%, respectively, and they significantly differed among the initial diameter, volume, and mass subgroups (all p < 0.001). The growth pattern of pGGNs may conform to the exponential model. Lobulated sign (p = 0.044), initial mean diameter (p < 0.001), volume (p = 0.003), and mass (p = 0.023) predicted pGGN growth. Persistent pGGNs showed an indolent course. Deep learning can assist in accurately elucidating the natural history of pGGNs. pGGNs with lobulated sign and larger initial diameter, volume, and mass are more likely to grow. • The pure ground-glass nodule (pGGN) segmentation accuracy of the Dr. Wise system based on convolution neural networks (CNNs) was 96.5% (573/594). • The median volume doubling time (VDT) of 52 pure ground-glass nodules (pGGNs) having grown was 1448days (range, 339-8640days), and their median mass doubling time (MDT) was 1332days (range, 290-38,912days). The mean time to growth in volume was 854 ± 675days (range, 116-2856days). • The 12-month, 24.7-month, and 60.8-month cumulative percentages of pGGN growth were 10%, 25.5%, and 51.1%, respectively, and they significantly differed among the initial diameter, volume, and mass subgroups (all p values < 0.001). The growth pattern of pure ground-glass nodules may conform to exponential model.

Late rupture of abdominal aortic aneurysm after endovascular repair

ObjectiveThe purpose of this study was to compare findings at presentation and surgical outcomes in patients in whom abdominal aortic aneurysms (AAAs) ruptured after endovascular repair and in patients in whom AAAs ruptured before any treatment during a defined period at a single center. MethodsThis is a retrospective analysis of consecutive patients who presented to Royal Prince Alfred Hospital with ruptured AAA from September 2003 to September 2014. Medical records of each patient were reviewed to retrieve demographics, findings at presentation, and surgical outcome. Comparison of the outcomes between those occurring after endovascular repair (group 1) and those occurring without previous endovascular treatment (group 2) was made using the data collected and combining the results obtained by a previous study that analyzed the same findings between 1992 and 2003 from the same center to provide a total 22-year experience (1992-2014) at a single quaternary referral center. ResultsFrom May 1992 to September 2014, there were 1921 elective repairs of intact infrarenal AAAs, with 1288 endovascular and 633 open repairs. During 22 years, 40 of the 1288 patients (3.1%) who underwent endovascular repair for AAA had rupture. The proportion of patients with hypotension at presentation in group 1 (13/40) was significantly less than in group 2 (108/138; P < .01). The difference in perioperative 30-day mortality rate in group 1 (8/40 [20%]) compared with group 2 (68/138 [49%]) was significant (P < .01). ConclusionsThis study confirmed that endovascular AAA repair does not prevent rupture in all patients. The data suggest that rupture, when it does occur, may not be accompanied by such major hemodynamic changes and higher mortality rate as with rupture of an untreated AAA. Strict surveillance and follow-up are required, especially in patients with relatively large initial AAA diameter or presence of endoleak and graft migration, to reduce the rate of ruptures after endovascular repair. Complete prevention will remain challenging because rupture may occur without any predisposing abnormalities. With the advent of new-generation devices, continuous larger long-term studies are required to document reduction in rupture rates after endovascular aneurysm repair.

Pliability and deflection of diagnostic catheters

The cardiac catheter is an intravascular catheter, which is introduced or implanted into the heart for diagnostic or therapeutic reasons. The catheters may break or king during their introduction and/or removal. The aim of the authors was to study the pliability of two catheters with the same material but different diameters according to the Food and Drug Administration's recommendation. The bending points, diameter decrease, deflection, and their correlation and dependence on the distance from the tip, as well as the influence of the initial diameter of the catheters were determined. The bending of catheters was performed on 9 bending points (120-280 mm from the tip by 20 mm) on 16 gauges with different radius (10-2.5 mm by 0.5 mm). A linear dependency between the diameter decrease and deflection was observed, which was independent from the placement of the measurement in both catheters examined. The larger initial diameter had significant (p = 0.05) greater diameter decrease than the smaller, but the curves characteristic of the diameter decrease and deflection were similar. The applied method seems to be useful for the examination of weak points of cardiac catheters.

Family history of aortic aneurysm is an independent risk factor for more rapid growth of small abdominal aortic aneurysms in Japan

We aimed to investigate risk factors associated with more rapid growth of abdominal aortic aneurysms (AAA) <50 mm (small AAAs) in Japan. We retrospectively investigated the clinical data of 374 patients with small AAAs (maximum diameter, ≤50 mm) who were referred to The University of Tokyo Hospital, Tokyo Medical University Hospital, or Saitama Medical Center, between 1995 and 2008. A total of 374 patients (321 men and 53 women) were followed up for a median of 66 months. The median diameter on initial examination was 40 mm, and the median growth rate of the AAAs was 2.1 mm/y. The growth rate of AAAs with an initial diameter ≥45 mm was significantly greater than those with an initial diameter <45 mm (3.3 mm/y vs 2.0 mm/y, respectively; P = .007). The growth rate of AAAs was significantly greater in patients with hypertension than in those without (2.3 mm/y vs 1.7 mm/y, respectively; P = .006) and in patients with a family history of aortic aneurysm than in those without (4.2 mm/y vs 2.0 mm/y, respectively; P = .009). Logistic regression analysis revealed that a large initial diameter and family history of aortic aneurysm were independent predictors of accelerated growth rate of small AAAs in Japan. In the present study, a large initial diameter and family history of aortic aneurysm were independent risk factors for more rapid growth of small AAAs. Although few studies have reported similar findings thus far, family history of aortic aneurysm should be carefully considered during follow-up of patients with small AAAs.

A clinical decision model for selecting the most appropriate therapy for uncomplicated chronic dissections of the descending aorta

The optimal treatment for patients with uncomplicated chronic Stanford type B aortic dissections (chTBADs) is still matter of debate. The purpose of this study was to design a decision tool to guide the surgeon in determining the preferred treatment option. A Markov decision-analysis model compared chTBAD patients treated with initial open surgical repair (OSR), thoracic endovascular aortic repair (TEVAR), and optimal medical therapy (OMT), followed during follow-up by OSR (OMT-OSR) or TEVAR (OMT-TEVAR), if indicated. Procedural risks, aortic growth and rupture rates, outcomes, and quality of life values were derived from the best available evidence in the literature. A chTBAD treatment strategy decision tool was developed, including the four key variables of age, sex, surgical risk, and maximum initial aortic diameter. Primary outcome was quality-adjusted life-years (QALYs). For the reference patient cohort, 55-year-old men with chTBAD with a maximum aortic diameter of 5.0cm, medium risk for surgery, and a threshold for surgery of 6.0cm during follow-up, OSR yielded higher QALYs, with 10.06 QALYs (95% credibility interval [CI], 9.52-10.56 QALYs) vs 9.92 QALYs (95% CI, 9.23-10.58 QALYs) after TEVAR and 9.64 QALYs (95% CI, 9.38-9.88 QALYs) and 9.40 QALYs (95% CI, 9.11-9.69 QALYs) for OMT-OSR and OMT-TEVAR. The difference between OSR and OMT-OSR was 0.42 QALYs (95% CI, 0.01-0.81 QALYs) and between TEVAR and OMT-TEVAR was 0.52 QALYs (95% CI, 0.04-0.68 QALYs). This showed that intervention is preferred over OMT. A change of the four variables resulted in a change of preferred treatment. In general, OSR was the preferred treatment in younger patients with a larger aortic diameter and in low-risk patients. TEVAR was preferred in elderly patients with large aortic diameter and if the aortic diameter threshold for repair decreased. OMT was the optimal therapy in high-risk patients, elderly patients, or in patients with small aortic diameters. This decision-analysis model shows that there is no "one-size-fits-all" treatment for uncomplicated chTBADs. For the reference patient cohort, intervention is preferred over OMT. Age is the most important deciding factor, followed by initial aortic diameter. Immediate OSR is the preferred treatment option in younger patients with a large initial aortic diameter and in low-risk patients. Immediate TEVAR is preferred in elderly patients with a large initial aortic diameter and in patients with a lower threshold for OSR. OMT should be considered in high-risk patients, in patients with small initial aortic diameters, and in patients aged >80years, unless their initial aortic diameter is >5.5cm. However, the differences in some patient groups are clinically insignificant, allowing a major role for patient preferences and hospital-specific considerations. This clinical decision model may guide chTBAD treatment.

Initial large diameter of common bile duct is associated with long‐term dilatation of bile duct after endoscopic extraction of stones

To investigate the time and extent of recovery of dilated common bile duct (CBD) after the extraction of CBD stones and to identify the factors related to the long-term dilatation of the CBD after stone removal. Data of 329 consecutive patients undergoing endoscopic extraction of CBD stones from January 2008 to December 2012 were retrospectively reviewed. Finally, 44 patients were enrolled in the study. The CBD diameter significantly decreased after stone extraction (P < 0.001). However, the CBD diameter in patients who were followed up for 1 week and longer and <1 week did not differ significantly. The diameter decreased more in patients with an initial CBD diameter ≥ 15 mm than in those with an initial CBD diameter <15 mm before stone extraction (P = 0.007), but the normalization of dilated CBD was less frequent in patients with a large initial CBD diameter. The factors related to the long-term dilatation of CBD (>10 mm for >6 months) were initial CBD diameter, the largest diameter of CBD stone and endoscopic papillary large balloon dilatation. Initial CBD diameter was an independent factor with multivariate analysis (OR 1.754, P = 0.017). The CBD diameter recovers rapidly after the extraction of CBD stones. An initial large CBD diameter before stone extraction is associated with the long-term dilatation of CBD.

Prediction of planted seedling survival of five Mediterranean species based on initial seedling morphology

Field performance can be predicted by evaluating nursery stock quality, but optimal morphological variables for use in these assessments may vary by species especially under dry Mediterranean conditions. Our objective was to identify initial seedling morphological characteristics that successfully predict field performance of five Mediterranean species (Pinus halepensis, Quercus ilex, Quercus coccifera, Ceratonia silqua and Pistacia lentiscus). Container seedling morphology was evaluated following the nursery phase, and then seedlings were outplanted in the field where field survival was monitored for two successive years. Results indicate that survival can successfully be predicted from seedling initial morphological characteristics for all these species, yet not all the initial characteristics were good predictors. Survival of P. halepensis and Pist. lentiscus seedlings was positively correlated to initial seedling root-collar diameter, total dry weight and Dickson’s quality index, and can be reliably predicted by these variables. In contrast, seedling field survival of the two Mediterranean evergreen oak species was correlated with few initial morphological attributes; initial diameter provided an accurate index to predict second-year outplanting survival for both species while height/diameter was a good survival predictor for Q. coccifera seedlings. For C. siliqua seedlings, seedlings with larger initial diameter and total biomass survive better in the field. Thus, diameter was the common variable that accurately predicted survival for all species, which should be >5 mm for P. halepensis seedlings and >7 mm for the remaining species.

Surface Energy effects on Catalyst Degradation in Low-Temperature PEMFCs

An in situ method to measure particle size changes on a PEMFC cathode is demonstrated. High energy, 58 keV, x-rays and PDF analysis of the data are used to calculate the average particle diameter during accelerated degradation experiments. Stability of Pt/C and Pt-Co/C with different initial particle sizes is investigated over 3000 cycles. The most stable electro-catalyst is the alloyed electro-catalyst with the larger initial diameter.

Modeling Smoke Plume-Rise and Dispersion from Southern United States Prescribed Burns with Daysmoke

We present Daysmoke, an empirical-statistical plume rise and dispersion model for simulating smoke from prescribed burns. Prescribed fires are characterized by complex plume structure including multiple-core updrafts which makes modeling with simple plume models difficult. Daysmoke accounts for plume structure in a three-dimensional veering/sheering atmospheric environment, multiple-core updrafts, and detrainment of particulate matter. The number of empirical coefficients appearing in the model theory is reduced through a sensitivity analysis with the Fourier Amplitude Sensitivity Test (FAST). Daysmoke simulations for “bent-over” plumes compare closely with Briggs theory although the two-thirds law is not explicit in Daysmoke. However, the solutions for the “highly-tilted” plume characterized by weak buoyancy, low initial vertical velocity, and large initial plume diameter depart considerably from Briggs theory. Results from a study of weak plumes from prescribed burns at Fort Benning GA showed simulated ground-level PM2.5 comparing favorably with observations taken within the first eight kilometers of eleven prescribed burns. Daysmoke placed plume tops near the lower end of the range of observed plume tops for six prescribed burns. Daysmoke provides the levels and amounts of smoke injected into regional scale air quality models. Results from CMAQ with and without an adaptive grid are presented.

Effects of snout dimensions on the hydrodynamics of suction feeding in juvenile and adult seahorses

Seahorses give birth to juveniles having a fully functional feeding apparatus, and juvenile feeding behaviour shows striking similarities to that of adults. However, a significant allometric growth of the snout is observed during which the snout shape changes from relatively short and broad in juveniles to relatively long and slender in adults. Since the shape of the buccal cavity is a critical determinant of the suction performance, this snout allometry will inevitably affect the suction feeding ability. To test whether the snout is optimised for suction feeding throughout an ontogeny, we simulated the expansion of different snout shapes varying from extremely long and slender to short and broad for juvenile and adult snout sizes, using computational fluid dynamic models. Our results showed that the snout diameter at the start of the simulations is involved in a trade-off between the realizable suction volume and expansion time on the one hand (improving with larger initial diameters), and maximal flow velocity on the other hand (improving with smaller initial diameters). Moreover suction performance (suction volume as well as maximal attainable flow velocity) increased with decreasing snout length. However, an increase in snout length decreases the time to reach the prey by the cranial rotation, which may explain the prevalence of long snouts among syngnathid fishes despite the reduced suction performance. Thus, the design of the seahorse snout revolves around a trade-off between the ability to generate high-volume suction versus minimisation of the time needed to reach the prey by the cranial rotation.

円筒穴広げ成形における&lt;br&gt;高強度鋼板の破断挙動に及ぼす初期穴加工条件の影響

Hole expansion using a flat-bottomed cylindrical punch was carried out to clarify the effects of piercing conditions on the fracture behavior of high-strength steel sheets. The results showed that the hole expansion rate λ negligibly changed with the piercing conditions in the case of a small initial hole diameter because of fracture from the inside of the edge of the hole. On the other hand, λ drastically changed in the case of a large initial hole diameter because of fracture from the edge of the hole. Moreover, by investigating the correlation between the quality of what around the hole and λ for a large initial hole diameter, it was clarified that λ of ferrite single-phase steel is affected by hardening behavior, and λ of ferrite-pearlite dual-phase steel is affected by the number of microvoids.

高強度鋼板の円筒穴広げ成形における&lt;br&gt;破断挙動に及ぼす初期穴径の影響

Hole expansion using a flat-bottomed cylindrical punch was carried out to clarify the fracture behavior of high-strength steel sheets by changing the initial hole diameter, d0. Experimental results showed that the hole expansion ratio, λ, became larger as the initial hole diameter, d0, increased. Moreover, the fracture site around the hole shifted considerably with the initial hole diameter, d0, in the case of high-strength steel sheets with high r-value. On the other hand, the analytical results exhibited poor coincidence with experimental ones when the initial hole diameter was small, whereas good correlation was observed with a large initial hole diameter. As a result, it was clarified that plastic deformation behavior during stretch flange forming performed using a flat-bottomed cylindrical punch is influenced not only by the planar anisotropy of the mechanical properties of steel sheets but also by the initial hole diameter.

Implosion dynamics and K-shell x-ray generation in large diameter stainless steel wire array Z pinches with various nesting configurations

Nested stainless steel wire array variations were investigated on the 20MA Z machine [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)]. In order to reach experimentally observed electron temperatures near 3.8keV and excite the K shell, these ∼6.7keV photon energy x-ray sources must be of large initial diameter (45–80mm) which poses a concern for magnetic Rayleigh–Taylor instability growth. We discuss the implosion dynamics in these large diameter wire arrays, including an analysis of the ablation phase indicating that the prefill material is snowplowed at large radius. Nested array configurations with various mass and radius ratios are compared for instability mitigation and K-shell scaling. Degradation of the K-shell x-ray power and yield was observed for shots that did not have simultaneous implosion of the outer and inner wire arrays. Shots that were designed per this constraint exhibited K-shell yield scaling consistent with the model of J. W. Thornhill et al. [IEEE Trans. Plasma Sci. 34, 2377 (2006)] which had been benchmarked to single array results. This lends confidence to K-shell yield predictions using this model for future shots on the refurbished Z machine. Initial results employing a triple nested wire array to stabilize the large diameter implosion are also reported.

Aneurysm Rupture after EVAR: Can the Ultimate Failure be Predicted?

Objectives To provide insight into the causes and timing of AAA rupture after EVAR. Design Original data regarding AAA ruptures following EVAR were collected from MEDLINE and EMBASE databases. Data were extracted systematically and patient and procedural characteristics were analyzed. Results 270 patients with AAA ruptures after EVAR were identified. Causes of rupture included endoleaks (in 160: type IA 57, type IB 31, type II 23, type III 26, type IV 0, endotension 9, unspecified 14), graft migration 41, graft disconnection 11 and infection 6. Most of the described AAA ruptures occurred within 2–3 years after EVAR. Mean initial AAA diameter was relatively large (65 mm). No abnormalities were present in 41 patients during follow-up before rupture. Structural graft failure was described in 96 and a fatal course in 119 patients. Conclusions Focus of surveillance on the first 2–3 years after EVAR may possibly reduce the AAA rupture rate, especially in patients with increased risk of early rupture (relatively large initial AAA diameter or presence of endoleak or graft migration). Better stent-graft durability and longevity is required to further reduce the AAA rupture risk after EVAR. Complete prevention will however remain challenging since AAA rupture may occur even if no predisposing abnormalities are present.