The long-timescale behavior of adsorbed carbon monoxide on the surface of amorphous water ice is studied under dense cloud conditions by means of off-lattice, on-the-fly, kinetic Monte Carlo ...simulations. It is found that the CO mobility is strongly influenced by the morphology of the ice substrate. Nanopores on the surface provide strong binding sites, which can effectively immobilize the adsorbates at low coverage. As the coverage increases, these strong binding sites are gradually occupied leaving a number of admolecules with the ability to diffuse over the surface. Binding energies and the energy barrier for diffusion are extracted for various coverages. Additionally, the mobility of CO is determined from isothermal desorption experiments. Reasonable agreement on the diffusivity of CO is found with the simulations. Analysis of the 2152 cm super(-1) polar CO band supports the computational findings that the pores in the water ice provide the strongest binding sites and dominate diffusion at low temperatures.
Abstract
Background
More than half of patients undergoing paraesophageal hernia repair (PEHR) will have radiographic hernia recurrence at 5 years after surgery. Gastropexy is a relatively low-risk ...intervention that may decrease recurrence rates, but it has not been studied in a prospective manner. Our study aims to evaluate the effect of anterior gastropexy on recurrence rates after PEHR, compared to no anterior gastropexy.
Methods
This is a two-armed, single-blinded, registry-based, randomized controlled trial comparing anterior gastropexy to no anterior gastropexy in PEHR. Adult patients (≥18 years) with a symptomatic paraesophageal hernia measuring at least 5 cm in height on computed tomography, upper gastrointestinal series, or endoscopy undergoing elective minimally invasive repair are eligible for recruitment. Patients will be blinded to their arm of the trial. All patients will undergo laparoscopic or robotic PEHR, where some operative techniques (crural closure techniques and fundoplication use or avoidance) are left to the discretion of the operating surgeon. During the operation, after closure of the diaphragmatic crura, participants are randomized to receive either no anterior gastropexy (control arm) or anterior gastropexy (treatment arm). Two hundred forty participants will be recruited and followed for 1 year after surgery. The primary outcome is radiographic PEH recurrence at 1 year. Secondary outcomes are symptoms of gastroesophageal reflux disease, dysphagia, odynophagia, gas bloat, regurgitation, chest pain, abdominal pain, nausea, vomiting, postprandial pain, cardiovascular, and pulmonary symptoms as well as patient satisfaction in the immediate postoperative period and at 1-year follow-up. Outcome assessors will be blinded to the patients’ intervention.
Discussion
This randomized controlled trial will examine the effect of anterior gastropexy on radiographic PEH recurrence and patient-reported outcomes. Anterior gastropexy has a theoretical benefit of decreasing PEH recurrence; however, this has not been proven beyond a suggestion of effectiveness in retrospective series. If anterior gastropexy reduces recurrence rates, it would likely become a routine component of surgical PEH management. If it does not reduce PEH recurrence, it will likely be abandoned.
Trial registration
ClinicalTrials.gov NCT04007952. Registered on July 5, 2019.
The Telescope Array (TA) observatory utilizes fluorescence detectors and surface detectors (SDs) to observe air showers produced by ultra high energy cosmic rays in Earth's atmosphere. Cosmic-ray ...events observed in this way are termed hybrid data. The depth of air shower maximum is related to the mass of the primary particle that generates the shower. This paper reports on shower maxima data collected over 8.5 yr using the Black Rock Mesa and Long Ridge fluorescence detectors in conjunction with the array of SDs. We compare the means and standard deviations of the observed X max distributions with Monte Carlo X max distributions of unmixed protons, helium, nitrogen, and iron, all generated using the QGSJet II-04 hadronic model. We also perform an unbinned maximum likelihood test of the observed data, which is subjected to variable systematic shifting of the data X max distributions to allow us to test the full distributions, and compare them to the Monte Carlo to see which elements are not compatible with the observed data. For all energy bins, QGSJet II-04 protons are found to be compatible with TA hybrid data at the 95% confidence level after some systematic X max shifting of the data. Three other QGSJet II-04 elements are found to be compatible using the same test procedure in an energy range limited to the highest energies where data statistics are sparse.
Background
Recurrent ventral hernia repair can be complex and requires a thorough understanding of prior interventions, myofascial releases, and location of prosthetic material. Without detailed ...operative reports, this information can be challenging to obtain, and some surgeons have suggested prior operative details can be discerned from radiographic imaging. We evaluated the accuracy and interrater reliability of surgeons to identify the type of prior VHR using CT imaging.
Methods
Fifteen expert abdominal wall reconstruction surgeons individually reviewed 21 CT scans of patients after various VHR approaches and determined the approach from a multiple-choice selection. Negative controls (no prior laparotomy) and positive controls (laparotomy without VHR) were also included. Surgeon accuracy and interrater reliability were measured.
Results
Surgeons were unable to identify the correct VHR over 50% of the time: open TAR and Rives–Stoppa were identified 42% of the time, open anterior component separation 24%, and robotic IPOM and eTEP 22% of the time, respectively. Surgeon interrater reliability, or agreement on answers—whether correct or incorrect—was fair (coefficient 0.23,
p
= 0.01).
Conclusions
Surgeons’ ability to accurately identify the type of previous VHR using post-operative CT scans is poor. Without the knowledge of prior repairs, surgeons may find it difficult to choose the best reoperative approach, anticipate operative complexities, and schedule appropriate OR time. All of which guides patient counseling and expectations. This highlights the importance to accurately reflect VHR details in operative reports and use necessary resources to obtain operative reports, since surgeons cannot reliably use CT scans to identify prior repairs.
Purpose
Incisional hernia is the most common complication of midline laparotomy. Although obesity is a known risk factor, the incidence of hernia formation in obese patients is not well defined. We ...sought to define the rate of incisional hernia formation in obese patients undergoing primary midline laparotomy in a large academic medical center.
Methods
Obese patients (BMI ≥ 30 kg/m
2
) who underwent an elective or urgent primary midline laparotomy from 2017 to 2021 at our institution were retrospectively identified. A blinded hernia surgeon reviewed imaging to assess for incisional hernia formation, defined as a midline fascial defect with intra-abdominal contents herniated outside of the peritoneal cavity.
Results
A total of 2241 patients met inclusion criteria. Cross-sectional imaging was available for 914 (41%) of these patients. The median BMI for all patients was 34.3 kg/m
2
(range 30.0–59.1). Median time to follow-up imaging was 316 days (181–957, IQR = 185) for all patients and 316 days (201–903, IQR = 184) for patients with incisional hernia. In total, 474 (51.9%) had radiographic evidence of an incisional hernia. Colorectal and General Surgery demonstrated the highest rate of incisional hernia (
p
< 0.001). During the study period, 138 patients (15.1%) underwent surgical repair of their hernia at our institution, with the highest percentage being Colorectal Surgery patients.
Conclusion
There is a high rate of hernia formation and subsequent hernia repair in obese patients undergoing midline laparotomy. Most importantly, these findings demonstrate an immediate and pressing need to identify the patient risk factors and technical issues related to this rate of hernia formation.
Evidence for a large-scale supergalactic cosmic-ray multiplet (arrival directions correlated with energy) structure is reported for ultra-high-energy cosmic-ray (UHECR) energies above 1019 eV using 7 ...years of data from the Telescope Array (TA) surface detector and updated to 10 years. Previous energy-position correlation studies have made assumptions regarding magnetic field shapes and strength, and UHECR composition. Here the assumption tested is that, because the supergalactic plane is a fit to the average matter density of the local large-scale structure, UHECR sources and intervening extragalactic magnetic fields are correlated with this plane. This supergalactic deflection hypothesis is tested by the entire field-of-view (FOV) behavior of the strength of intermediate-scale energy-angle correlations. These multiplets are measured in spherical cap section bins (wedges) of the FOV to account for coherent and random magnetic fields. The structure found is consistent with supergalactic deflection, the previously published energy spectrum anisotropy results of the TA (the Hotspot and Coldspot), and toy-model simulations of a supergalactic magnetic sheet. The seven year data posttrial significance of this supergalactic structure of multiplets appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be 4.2 . The 10 years of data posttrial significance is 4.1 . Furthermore, the starburst galaxy M82 is shown to be a possible source of the TA Hotspot, and an estimate of the supergalactic magnetic field using UHECR measurements is presented.
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