Predicting DNAPL entrapment and recovery: the influence of hydraulic property correlation

The influence of aquifer property correlation on multiphase fluid migration, entrapment and recovery was explored by incorporating correlated and uncorrelated porosity, permeability, and capillary pressure-saturation (P c -Sat) parameter fields in a cross-sectional numerical multiphase flow model. Comparison of two-dimensional entrapped organic saturation distributions for a simulated tetrachloroethylene (PCE) spill in ensembles of aquifer realizations suggests that the degree of spatial correlation in P c -Sat parameters exerts a controlling influence on dense nonaqueous phase liquid (DNAPL) spreading and redistribution in saturated aquifers. The predicted evolution of DNAPL source zones and resultant remediation efficiency under surfactant enhanced aquifer remediation (SEAR) also appear to be strongly influenced by the spatial correlation of aquifer parameters and multiphase flow constitutive relationships. Results for a limited number of realizations selected from each ensemble showed that removal of 60% to 99% of entrapped PCE could reduce dissolved contaminant concentration and mass flux by approximately two orders of magnitude under natural gradient conditions. Aqueous phase contaminant mass flux did not vary uniformly as a function of % DNAPL removed, however, and notable differences in behavior were observed for models incorporating correlated versus uncorrelated P c -Sat and permeability fields. Although these results must be confirmed through analysis of additional realizations, it is likely that similar or larger differences between correlated and uncorrelated system behavior will be observed in aquifers with greater spatially variability than that of the nonuniform, homogeneous sand aquifer studied here.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47837/1/477_2003_Article_162.pd

Treatment of esophageal achalasia in children: Today and tomorrow

Esophageal achalasia (EA) is a rare esophageal motility disorder in children. Laparoscopic Heller myotomy (LHM) represents the treatment of choice in young patients. Peroral endoscopic myotomy (POEM) is becoming an alternative to LHM. The aim of this study is to evaluate the effectiveness, safety, and outcomes of POEM vs LHM in treatment of children with EA. Data of pediatric patients with EA, who underwent LHM and POEM from February 2009 to December 2013 in two centers, were collected. Eighteen patients (9 male, mean age: 11.6 years; range: 2-17 years) were included. Nine patients (6 male, mean age: 10.7 years; range: 2-16 years) underwent LHM, and the other 9 (3 males, mean age: 12.2 years; range: 6-17 years) underwent POEM procedure. Mean operation time was shorter in POEM group compared with LHM group (62/149 minutes). Myotomy was longer in POEM group than in LHM group (11/7 cm). One major complication occurred after LHM (esophageal perforation). No clinical and manometric differences were observed between LHM and POEM in follow-up. The incidence of iatrogenic gastroesophageal reflux disease was low (1 patient in both groups). Results of a midterm follow-up show that LHM and POEM are safe and effective treatments also in children. Besides, POEM is a mini-invasive technique with an inferior execution timing compared to LHM. A skilled endoscopic team is mandatory to perform this procedur

Esophagogastric dissociation versus fundoplication: Which is best for severely neurologically impaired children?

Purpose: Neurologically impaired children (NIC) often have swallowing difficulties, severe gastroesophageal reflux, recurrent respiratory infections, and malnutrition. Bianchi pro posed esophagogastric dissociation (EGD) as an alternative to fundoplication and gastrostomy. The authors compared these 2 approaches.Methods: Twenty-nine consecutive symptomatic NIC refractory to medical therapy were enrolled in a prospective study and divided into 2 groups: A (n = 12), NIC who underwent fundoplication and gastrostomy; B (n = 14), NIC who underwent EGD. Three were excluded because of previous fundoplication, Anthropometric (percentage of the 50th percentile/ age of healthy children) and biochemical parameters, respiratory infections per year, hospitalization (days per year), feeding time (minutes), and "quality of life" (parental psychological questionnaire, range 0 to 60), were analyzed (t test and Mann-Whitney test) preoperatively and 1 year postoperatively. Complications were recorded.Results: Compared with group A, group B presented a statistically significant increase of all anthropometric and nearly all biochemical parameters with a statistical difference in terms of respiratory infections, hospital stay, feeding time, and psychological questionnaire. In group A, 2 bowel obstructions, 1 tight fundoplication, 1 dumping syndrome, and 3 failures of fundoplication occurred. Group B presented 1 anastomotic stricture, 1 paraesophageal hernia, and 1 bowel obstruction.Conclusions: Compared with fundoplication and gastrostomy, EGD offered better nutritional rehabilitation, reduction in respiratory infections, and improved quality of life. EGD can be rightfully chosen as a primary procedure. J Pediatr Surg 36:677-680. Copyright (C) 2001 by W.B. Saunders Company

Investigation of the fusion process for B 10 + Au 197 at near-barrier energies

In a previous work, we presented data for the B10+Au197 system, corresponding to quasielastic and elastic scattering, Au197 inelastic excitation, and one neutron pickup transfer, measuring the angular distribution of scattered beam-like ejectiles at several energies around the Coulomb barrier. In this paper, we present data for the fusion process of the same system, at several energies around the Coulomb barrier, as well as new data for one neutron pickup and stripping transfer. In this case, we detected offline γ rays stemming from the β-delayed decay chain of fusion-evaporation residues and heavy transfer products. As in our previous work, we analyzed this data set with coupled reaction channels calculations using the São Paulo potential. We show that the coupling to the one neutron transfer channel is quite important to describe the fusion data at the sub-barrier energy region. We also provide a comparison of the experimental fusion cross sections obtained for B10+Au197 with data for several other systems involving the same target nucleus.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina) PIP00786COFondo para la Investigacin Cientfica y Tecnolgica (FONCYT, Argentina) PICT-2017-4088Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Brazil) 2018/09998-8, 2019/07767-1, 2019/05769-7Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil) 302160/2018-3, 304056/2019-7Ministerio de Ciencia, Innovación y Universidades PGC2018-096994-B-C2

9^9Be+120^{120}Sn scattering at near-barrier energies within a four body model

Cross sections for elastic and inelastic scattering of the weakly-bound $^9$Be nucleus on a $^{120}$Sn target have been measured at seven bombarding energies around and above the Coulomb barrier. The elastic angular distributions are analyzed with a four-body continuum-discretized coupled-channels (CDCC) calculation, which considers $^9$Be as a three-body projectile ($\alpha$ + $\alpha$ + n). An optical model analysis using the S\~ao Paulo potential is also shown for comparison. The CDCC analysis shows that the coupling to the continuum part of the spectrum is important for the agreement with experimental data even at energies around the Coulomb barrier, suggesting that breakup is an important process at low energies. At the highest incident energies, two inelastic peaks are observed at 1.19(5) and 2.41(5) MeV. Coupled-channels (CC) calculations using a rotational model confirm that the first inelastic peak corresponds to the excitation of the 2$_1^+$ state in $^{120}$Sn, while the second one likely corresponds to the excitation of the 3$_1^-$ state.Comment: 11 pages, 9 figures. Accepted as PR

Experimental Search for Solar Axions via Coherent Primakoff Conversion in a Germanium Spectrometer

Results are reported of an experimental search for the unique, rapidly varying temporal pattern of solar axions coherently converting into photons via the Primakoff effect in a single crystal germanium detector. This conversion is predicted when axions are incident at a Bragg angle with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1 kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of $g_{a\gamma \gamma} < 2.7\cdot 10^{-9}$ GeV$^{-1}$, independent of axion mass up to ~ 1 keV.Comment: RevTeX, 11 pages, figures can be obtained by fax from [email protected]. Submitted to Phys. Lett.