MODELING OF MINERAL TRAPPING FOR CO2 SEQUESTRATION

In order to prevent CO2 concentrations in the atmosphere from rising to unacceptable levels, carbon dioxide is sequestered beneath the ground surface. CO2 can be trapped as a gas under a low-permeable cap rock (structural trapping) or can dissolve into the ground water (hydrodynamic trapping); it can also react with minerals and organic matter that are dissolved in the brine to form precipitates (mineral trapping). From the perspective of secure, long term storage, mineral trapping has been identified as the most effective mechanism related to subsurface sequestration. Temperature, pressure and salinity are among the primary parameters governing the overall behavior of the process of mineral trapping. In this study, the primary goal is to simulate the behavior of carbon dioxide with an improved model under the conditions of temperature and pressure typical of saline aquifers, i.e. 50 to 100oC and 1-500 bar, respectively. The objective is to determine how the related quantities of molar volume as well as CO2 fugacity change in response to changes in pressure and temperature so that the associated changes in the solubility and the precipitation of carbonates, indicating the rate of CO2 consumption, can be quantified. This study finds that the dissolution rate of anorthite and the rate of precipitation of calcite both rise with the increase in pressure and temperature. The dissolution rate of anorthite has been found to be the rate-limiting process in the sequestration of CO2 and governs the consumption rate of CO2 in the aqueous phase. These results show good agreement with those obtained from experimental work reported in other studies. This study also agrees earlier findings based on relatively less precise models, with respect to the increase in CO2 solubility at higher pressures and a decrease in solubility associated with increasing values of temperature and salinity

The Role of EUS in Pancreatic Cysts

Pancreatic cystic lesions (PCLs) comprise various pathologically different groups of lesions that usually share many common clinical features. Cystic lesions and fluid collections of the pancreas often present a diagnostic and therapeutic challenge. Pancreatic cystic lesions are being diagnosed with increasing frequency owing to the widespread use of cross-sectional imaging. The differential diagnosis for cystic lesions of the pancreas is broad, and the role of endoscopic ultrasonography (EUS) is becoming more clearly defined. EUS has become an important tool in the diagnosis and risk stratification of pancreatic cysts. The ability of EUS to provide detailed imaging, tissue, and cyst fluid for analysis makes it a seemingly powerful diagnostic tool for PCLs. It can accurately visualize the cyst morphology, assess vascular pattern by contrast harmonic scan, and perform fine-needle aspiration (FNA) for evaluation of cytology and molecular markers. Furthermore, several studies have shown the therapeutic applications of endoscopic ultrasound in management of PCLs, including EUS-guided ablation of cystic pancreatic tumors by injection of alcohol, aiding in pancreatic pseudocyst drainage

ABC: A Simple Explicit Congestion Controller for Wireless Networks

We propose Accel-Brake Control (ABC), a simple and deployable explicit congestion control protocol for network paths with time-varying wireless links. ABC routers mark each packet with an "accelerate" or "brake", which causes senders to slightly increase or decrease their congestion windows. Routers use this feedback to quickly guide senders towards a desired target rate. ABC requires no changes to header formats or user devices, but achieves better performance than XCP. ABC is also incrementally deployable; it operates correctly when the bottleneck is a non-ABC router, and can coexist with non-ABC traffic sharing the same bottleneck link. We evaluate ABC using a Wi-Fi implementation and trace-driven emulation of cellular links. ABC achieves 30-40% higher throughput than Cubic+Codel for similar delays, and 2.2X lower delays than BBR on a Wi-Fi path. On cellular network paths, ABC achieves 50% higher throughput than Cubic+Codel

Endoscopic Ultrasonography (EUS) and Gallbladder

Diseases of the gallbladder commonly manifest as cholelithiasis and gallbladder cancer. Cholelithiasis has become a significant health problem in developed societies, affecting 10–15% of the adult population. Gallbladder polyps are incidentally detected in approximately 4–7% of patients. In addition, other gallbladder problems may also occur, but these are extremely rare: remnant cystic duct, gallbladder anomalies, Mirizzi syndrome, and gallbladder parasites. Endoscopic ultrasound (EUS) is an excellent method for visualizing the bile duct and gallbladder given its proximity when imaging from the duodenum. EUS can be used for evaluation of gallbladder disease that includes investigation of suspected cholelithiasis or biliary sludge, imaging of polypoid lesions of the gallbladder, and diagnosis and staging of gallbladder cancer. This procedure can be helpful to further distinguish benign from malignant or potentially malignant gallbladder polyps and play an important role in determining the treatment strategy for gallbladder polyps. Furthermore, EUS can help in the diagnosis of rarely gallbladder diseases such as remnant cystic duct, gallbladder anomalies, Mirizzi syndrome, and gallbladder parasites. Recent studies have suggested that EUS‐guided gallbladder drainage (EUS‐GBD) can be considered to be an effective emergency treatment for acute cholecystitis patients at high risk for surgery