Subsequent Drainage Research Articles

A Rare Cause of Dysphagia: Mediastinal Pancreatic Pseudocyst

Mediastinal pancreatic pseudocysts are a rare complication of acute and chronic pancreatitis. They occur as a result of posterior rupture of the pancreatic duct into the retroperitoneal space and subsequent drainage of pancreatic fluids though the diaphragmatic orifices into the mediastinum. No uniform diagnostic or treatment standards exist in the management of these cysts. Here we report the case of a 50-year-old male with history of alcohol abuse and recurrent pancreatitis, last episode ten months prior, who presented with rapidly progressive dysphagia and odynophagia. He was previously evaluated at another institution where a cardiac workup was noted to be negative and he was discharged home with a diagnosis of esophageal spasm. On presentation to our facility, patient was afebrile, hemodynamically stable, with a normal physical exam and normal labs. Chest radiography on admission showed small pleural effusions bilaterally and bibasilar opacities attributed to atelectasis or pneumonia. CT chest was notable for multiple cystic lesions in the gastroesophageal (GE) junction and gastrosplenic regions with associated stenosis of the esophagus at GE junction (Figures 1 and 2). A subsequent CT abdomen and pelvis with contrast revealed a large 5 x 4 cm pseudocyst anterior to the distal GE junction with mass effect and compression. Endoscopic ultrasound (EUS) was performed revealing a heterogenous periesophageal cyst, measuring 4 cm x 6.7 cm with mixed liquid and solid components (Figure 3). The cyst fluid was successfully aspirated with a transesophageal FNA. The remaining cyst with solid debris measured 2.5 x 5 cm after drainage. Analysis of the aspirate was notable for an amylase level of 4136 (U/L) and CEA of 4.8 (mg/dL) thus confirming diagnosis of pseudocyst. The patient was subsequently discharged and has been symptom free since. There are fewer than 100 reported cases of mediastinal pancreatic cyst expansion. This case highlights a rare presentation of a common complication of recurrent pancreatitis and illustrates the importance of considering pancreatic pseudocyst expansion into the mediastinum as a cause of dysphagia and odynophagia in these patients.Figure: CT Chest demonstrating cyst compressing esophagus at GE junction in sagittal view.Figure: CT Chest demonstrating cyst compressing esophagus at GE junction in coronal view.Figure: EUS image of FNA needle in mediastinal pancreatic pseudocyst.

Potential role of the Virchow Robin space in the pathogenesis of bacterial meningitis

Meningitis is an infectious disease commonly arising from a bacterial etiology. The rapid progression of morbidity and mortality due to bacterial meningitis requires critical and imminent time-dependent clinical intervention. Although it is unambiguously clear that bacteria must infiltrate the cerebrospinal fluid, the sequence of events in the pathogenesis of bacterial meningitis has not been fully elucidated. Most reviews of the pathogenesis of bacterial meningitis do not specify the anatomical location of bacteria following BBB traversal. We propose an additional hypothesis focusing on the Virchow-Robin space (VRS). The VRS consists of a small, but identifiable perivascular space formed by a sheath of cells derived from the pia mater. The VRS has been described as an immunological space and possibly having a role in several neuropathological diseases. Solute exchange between cerebrospinal fluid and extracellular fluid occurs at the VRS, with subsequent drainage into the subarachnoid space. Because the VRS is continuous with the subpial space, a more direct route to the meninges is facilitated.The involvement of the VRS may have profound implications on the pathogenesis and therapeutic strategies: (1) nasopharyngeal colonization; (2) penetration into the blood stream after crossing the mucosal and epithelial membranes; (3) proliferation in the bloodstream; (4) extravasations through the endothelium of the post-capillary venules to the perivascular VRS; (5) migration from VRS to subpial space; (6) traversal through pia mater, entering the CSF in the subarachnoid space; (7) invasion of the meninges. The implication of the VRS in the pathogenesis of bacterial meningitis would be twofold. First, the VRS could provide an additional route of entry of bacteria into the brain. Second, the VRS could provide an area for bacterial proliferation, and thereby serve as a bacterial reservoir in relatively close proximity to the meninges.The clinical consequences of this hypothesis are: 1) clinical interpretation of laboratory findings, and 2) effective antibiotic delivery into the VRS. If the role of the VRS is established as part of bacterial meningitis pathogenesis, antibiotic pharmacokinetics and pharmacodynamics in the VRS need to be determined. This may result in developing novel antibiotic delivery and clinical strategies to improve morbidity and mortality.

Acid sulfate soil evolution models and pedogenic pathways during drought and reflooding cycles in irrigated areas and adjacent natural wetlands

The severe Millennium Drought (2007–2010) left an area of over 5000ha in the Lower Murray River (South Australia) dried, cracked and acidified as river and groundwater levels fell nearly 2m. In this study, we examined irrigated agricultural areas and an adjacent natural wetland for comparison, which were both affected by the drought. Approximately 3m deep soil cores were collected along transects in three sections of the Lower Murray Reclaimed Irrigation Area (LMRIA) on multiple occasions between 2011 and 2015 and an adjacent natural wetland in 2007. Soil properties measured included pH, reduced inorganic sulfur (RIS, pyrite), titratable actual acidity (TAA), retained acidity, acid neutralising capacity (ANC), X-ray diffraction analyses and scanning electron microscopy. A series of explanatory soil-regolith hydro-toposequence models were developed during the pre-drought period, drying period, and subsequent wetting/reflooding post-drought period. These models indicate that prior to draining of the natural wetlands for irrigated agriculture the region cycled between wetting and flushing, and partial drying conditions in response to seasonal and climatic cycles causing the build-up of hypersulfidic material to be kept in check by oxidation of pyrite during dry periods/droughts and removal during scouring floods. As the region became managed for navigation and irrigation by installing barrages and locks, pyrite began to build-up. The extreme lowering of the water table during the Millennium Drought resulted in deep oxidation of sulfides in anaerobic hypersulfidic material to depths >3.5m in the previously saturated irrigated pastures and within 50cm of the soil surface in the natural wetlands. Oxidation and acidification between 0.5 and 3.5m of Hypersulfidic clayey soils was enhanced by the formation of large cracks up to 3.5m deep. Rewetting and flooding after the drought caused mobilization of sulfuric acid, soluble sulfates, ferrous iron, nutrients and metals with transport into the River Murray. Our findings highlight that irrigated areas formed deeper sulfuric materials (>3.5m) than in adjacent natural wetlands (<1m) due to the difficulties in the management of water tables in irrigation areas because of the installation of high levee banks and deep drains. Maintaining water tables on agricultural soils via irrigation and subsequent drainage will promote the rapid formation of deep (>3.5m) acid sulfate soils with sulfuric material containing extensive retained acidity (jarosite), which can persist for decades or longer.

Cosmogenic10Be dating of raised shorelines constrains the timing of lake levels in the eastern Lake Agassiz-Ojibway basin

AbstractSurface exposure dating was applied to erosional shorelines associated with the Angliers lake level that marks an important stage of Lake Ojibway. The distribution of 1510Be ages from five sites shows a main group (10 samples) of coherent10Be ages yielding a mean age of 9.9±0.7 ka that assigns the development of this lake level to the early part of the Lake Ojibway history. A smaller group (3 samples) is part of a more scattered distribution of older10Be ages (with 2 outliers) that points to an inheritance of cosmogenic isotopes from a previous exposure, revealing an apparent mean age of 15.8±0.9 ka that is incompatible with the Ojibway inundation and the regional deglaciation. Our results provide the first direct10Be chronology on the sequence of lake levels in the Ojibway basin, which includes the lake stage presumably associated with the confluence and subsequent drainage of Lakes Agassiz and Ojibway. This study demonstrates the potential of this approach to date glacial lake shorelines and underlies the importance of obtaining additional chronological constraints on the Agassiz-Ojibway shoreline sequence to confidently assign a particular lake stage and/or lake-level drawdown to a specific time interval of the deglaciation.

Phosphorus Dynamics in Long-Term Flooded, Drained, and Reflooded Soils

In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P) into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were selected. We flooded-drained-reflooded two soils for 35 d, then drained the soils, and 10 d later reflooded the soils for 17 d. Dissolved reactive phosphorus (DRP), soil inorganic P fractions, Olsen P, pH, and Eh in floodwater and pore water were analyzed. The wheat-growing soil had significantly higher floodwater DRP concentrations than vegetable-growing soil, and floodwater DRP in both soils decreased with the number of flooding days. During the reflooding period, DRP in overlying floodwater from both soils was less than 0.87 mg/L, which was 3–25 times less than that during the flooding period. Regardless of flooding or reflooding, pore water DRP decreased with flooding days. The highest concentration of pore water DRP observed at a 5-cm depth. Under the effect of fertilizing and flooding, the risk of vertical P movement in 10–50 cm was enhanced. P diffusion occurred from the top to the bottom of the soils. After flooding, Al-P increased in both soils, and Fe-P, O-P, Ca2-P decreased, while Fe-P, Al-P, and O-P increased after reflooding, When Olsen P in the vegetable-growing soil exceeded 180.7 mg/kg and Olsen P in the wheat-growing soil exceeded 40.8 mg/kg, the concentration of DRP in pore water increased significantly. Our results showed that changes in floodwater and pore water DRP concentrations, soil inorganic P fractions, and Olsen P are significantly affected by fertilizing and flooding; therefore, careful fertilizer management should be employed on flooded soils to avoid excess P loss.

Difference in growth and coalescing patterns of droplets on bi-philic surfaces with varying spatial distribution

This paper reports the condensation and subsequent motion of water droplets on bi-philic surfaces, surfaces that are patterned with regions of different wettability. Bi-philic surfaces can enhance the water collection efficiency: droplets condensing on hydrophobic regions wick into hydrophilic drain channels when droplets grow to a certain size, renewing the condensation on the dry hydrophobic region. The onset of drain phenomenon can be triggered by multiple events with distinct nature ranging from gravity, direct contact between a droplet and a drain channel, to a mutual coalescence between droplets. This paper focuses on the effect of the length scale of hydrophobic regions on the dynamics of mutual coalescence between droplets and subsequent drainage. The main hypothesis was that, when the drop size is sufficient, the kinetic energy associated with a coalescence of droplets may cause dynamic advancing of a newly formed drop, leading to further coalescence with nearby droplets and ultimately to a chain reaction. We fabricate bi-philic surfaces with hydrophilic and hydrophobic stripes, and the result confirms that coalescing droplets, when the length scale of droplets increases beyond 0.2mm, indeed display dynamic expansion and chain reaction. Multiple droplets can thus migrate to hydrophilic drain simultaneously even when the initial motion of the droplets was not triggered by the direct contact between the droplet and the hydrophilic drain. Efficiency of drain due to mutual coalescence of droplets varies depending on the length scale of bi-philic patterns, and the drain phenomenon reaches its peak when the width of hydrophobic stripes is between 800μm and 1mm. The Ohnesorge number of droplets draining on noted surfaces is between 0.0042 and 0.0037 respectively. The observed length scale of bi-philic patterns matches that on the Stenocara beetle’s fog harvesting back surface. This match between length scales suggests that the surface of the insect is optimized for the drain of harvested water.

Laparoscopic Lavage in the Management of Perforated Diverticulitis: a Contemporary Meta-analysis

ImportancePerforated diverticulitis carries the risk of significant comorbidity and mortality. Although colon resection provides adequate source control, the procedure itself carries morbidity, as well as later stoma reversal procedures. The effectiveness of laparoscopic lavage to treat perforated diverticulitis remains unclear. ObjectiveWe aimed to conduct a meta-analysis to evaluate current studies comparing laparoscopic lavage with colon resection in cases of perforated diverticulitis for the effectiveness in source control, without the need for subsequent interventions, stoma formation, and death. Data SourcesElectronic database searches were conducted using EMBASE, Pubmed, CINAHL, Cochrane databases, and clinicaltrials.gov following PRISMA guidelines. Study SelectionRandomized controlled trials (RCTs) were included that compared laparoscopic lavage against colon resection for perforated diverticulitis. Data Extraction and SynthesisRisk of bias in RCT’s was assessed the Cochrane Assessment of Bias risk tool and Jadad scale. A meta-analysis was performed using random-effects risk ratios (RR) and 95% confidence intervals (CI). Main OutcomeOutcome measures included the total rate of reoperation, rate of reoperation for infection, need for subsequent percutaneous drainage, stoma formation, and mortality rate within 90 days. ResultsThree eligible randomized controlled studies were identified, with a combined total of 372 patients. Laparoscopic lavage carried an increased rate of total reoperations (RR 2.07; CI 1.12–3.84; p = 0.021) and an increased rate of reoperation for infection (RR 5.56; CI 1.97–15.69; p = 0.001) compared with colon resection. In addition, laparoscopic lavage increased the rate of subsequent percutaneous drainage (RR 6.54; CI 1.77–24.16; p = 0.005) compared with colon resection, but a lesser risk of stoma formation within 90 days (RR 0.18; CI 0.12–0.27; p < 0.001). No difference in mortality rate was observed between treatments (RR 1.03; CI 0.45–2.34; p = 0.950). ConclusionDespite decreased rates of stoma formation and equivalent mortality rates as compared with colon resection, laparoscopic lavage for Hinchey III diverticulitis fails to completely control the source of infection. Our data show that laparoscopic lavage is associated with increased rates of total reoperations, increased rates of reoperation for infections, and need for subsequent percutaneous drainage.

Quaternary history of the Kiseiba Oasis region, southern Egypt

Kiseiba Oasis and depression are located in southern Egypt between the Selima Sand Sheet to the west and the Nile to the east, an important area that hosted Late Cenozoic drainage, Middle Pleistocene lakes, and numerous Paleolithic and Neolithic cultural sites. A synthesis of orbital data, field surveying and near-surface stratigraphy provides new insights into the Quaternary history of this region. Shuttle Imaging Radar data show a complex of fluvial channels that are due to stringers of surficial fluvial lag, subsurface fluvial deposits, and areas of deep alluvium. Three topographic surfaces are described: 1) the Atmur El-Kibeish, above 230 m elevation, which displays a linear pattern of light radar returns, possibly formed from northeast drainage; 2) the Acheulean Surface, at 200 m elevation, that has dark radar patterns resulting from thick alluvium bounded by pebble sand and calcrete strata, and 3) the Kiseiba Surface, below 190 m, that has a complex series of surface and subsurface fluvial and aeolian sediments. Initial drainage from the Early through Middle Pleistocene was to the northeast, which may have lasted through the Last Interglacial. Later reworking of sediments during the Last Glacial Maximum and the Holocene resulted in topographic inversion, with any subsequent local drainage on the Kiseiba Surface to the southwest, towards the Kiseiba Scarp.

Endoscopic Ultrasound-Guided Pancreatic Duct Intervention.

Endoscopic ultrasound-guided pancreatic duct intervention (EUS-PDI) is an emerging endoscopic approach allowing access and intervention to the pancreatic duct (PD) for patients with failed endoscopic retrograde pancreatography (ERP) or patients with surgically altered anatomy. As opposed to biliary drainage for which percutaneous drainage is an alternative following failed endoscopic retrograde cholangiopancreatography (ERCP), the treatment options after failed ERP are very limited. Therefore, endoscopic ultrasound (EUS)-guided access to the PD and options for subsequent drainage may play an important role as an alternative to surgical intervention. However, this approach is technically demanding with a high risk of complications, and should only be performed by highly experienced endoscopists. In this review, we describe an overview of the current endoscopic approaches, basic technical tips, and outcomes using these procedures.

Late Pliocene-Pleistocene environments and glacial history of the northern North Sea

Based on new geochronological (amino acids and Sr-isotopes) and lithological data combined with analyses of 3D seismic data, the Pliocene-Pleistocene development of the central northern North Sea has been investigated. At the start of the Plio-Pleistocene Transition the study area was dominated by a deltaic, shallow marine or tidal depositional environment with sediments mainly sourced from the west. These sand-rich sediments include green glauconitic grains that belong to the Utsira Sand with a local provenance. Directly above the base Quaternary (R2) a 60 m thick layer of mud-rich sediments of glacimarine origin were deposited at a rate of ∼12 cm/ka between ∼2–1.5 Ma and up to 80 cm/ka between 1.5 and 1.2 Ma possibly reflecting glacial ice advancing to the Norwegian coastline. The high rate of deposition in the Early Pleistocene occurred immediately before the initiation of the Norwegian Channel Ice Stream at ∼1.1 Ma. Following this, a large part of the sediment input from Fennoscandia seems to have been directed away from the study area to the shelf break. At the start of the Mid Pleistocene Transition (MPT), subaerial conditions allowed the formation of a >50 km long fluvial channel across the study area draining water from the east to the south west. The earliest evidence of grounded ice in the investigated area comes from mega scale glacial lineations formed during the MPT, at or just after ∼1.2 Ma. Following this, a regional unconformity (R4) was formed by one or more grounded ice advances across the study area possibly during or directly after the MPT and likely marks the boundary between the Early and Mid Pleistocene glacimarine sediments. The Mid to Late Pleistocene stratigraphy is dominated by glacimarine sediments and tills and is associated with multiple generations of tunnel valleys observed within the seismic data. A high shear strength till containing chalk clasts transported from the west and/or south of the study area was likely deposited during MIS6 and may have been more conducive to tunnel valley formation in comparison to lower shear strength tills deposited by later ice advances. A thick till unit overlain by a sand layer in the study area was deposited by grounded ice during the Last Glacial Maximum and subsequent drainage of an ice dammed lake in the southern North Sea during the last deglaciation (MIS2) of the study area. This study shows that much of the Quaternary age sediments within the northern North Sea were deposited relatively rapidly during short periods of time probably leaving significant hiatuses within the stratigraphic record. This finding has implications for previous studies that use a chronological framework assuming a relatively continuous sedimentation rate and record for the Early Pleistocene within the North Sea.

Electrolyzed Saline Irrigation for Elimination of Bacterial Colonization in the Empyema Space.

Background: The empyema space is refractory to elimination of bacterial colonization. Electrolyzed saline (ES) was used as intra-pleural irrigation for rapid disinfection of the empyema space.Patients and Methods: Twenty consecutive patients with para-pneumonic empyema were reviewed in this study from 2007 to 2015. The empyema space was irrigated by miniaturized thoracoscopic surgery (mini VATS), and the efficacy and safety of the use of ES were evaluated.Results: Sixteen patients were male and four were female, with a mean age of 66.5 ± 9.5 y (27–90 y). Bacterial cultures of the purulent effusions from all 20 patients had positive results. Seventeen patients subsequently underwent continuous catheter irrigation and drainage. No patient had chest pain during ES irrigation. Fever duration after mini VATS was 2.8 ± 1.8 d (0–5 d). Catheter indwelling time was 10.3 ± 7.2 d (3–33 d). Inflammatory markers significantly improved (p < 0.05) within a week after mini VATS. Eighteen patients achieved pleural disinfection, and two patients had residual pathogens, one of whom later died of lung abscess. Space closure was successful in 14 patients. No patient underwent subsequent open drainage. Nineteen (95%) patients were discharged from the hospital. This treatment was successful in 18 (90%) patients, and one (5.6%) patient experienced recurrence.Conclusions: The ES irrigation facilitates the rapid disinfection and closure of the empyema space.

A case of multiple empyema caused by Streptococcus intermedius

We report the case of a patient with multiple empyema present throughout his body, including chronic sinusitis and chronic suppurative otitis media, as well as subsequent epidural empyema, all caused by Streptococcus intermedius. A 38-year-old man presented with chief complaints of headache, left ear discharge, and nasal congestion. Imaging studies revealed pansinusitis, soft tissue signs in the mastoid cells, and otitis media. The patient was treated with meropenem hydrate, 6g/day. While clinical findings indicated improvement of the sinusitis, his headache did not improve. Further examination with contrast computerized tomography (CT) ‘a chest radiography’ blood cultures were performed, and the patient was diagnosed with multiple empyema (with an epidural empyema, pulmonary suppuration) caused by S. intermedius. Subsequent burr hole drainage was implemented to drain the epidural empyema. Long-term administration was required to treat pulmonary suppuration. While they remain rare, there has been a recent upward trend in the frequency of cases in which a young, previously healthy patient has developed multiple empyema throughout their body despite the absence of complicating diseases that pose an immune deficiency risk, such as diabetes or infection with the human immunodeficiency virus (HIV). In order to properly diagnose and treat patients presenting with multiple empyema infection with S. intermedius should be included in the differential diagnosis.

Retraction Note to: Improving the diagnosis, treatment, and biology patterns of feline mammary intraepithelial lesions: a potential model for human breast masses with evidence from epidemiologic and cytohistopathologic studies.

In this study, the frequency of different types of mammary masses and their relationship with cytohistopathologic changes was investigated and data on history, macroscopic description, clinical examination and treatment were collected. To determine the prevalence and types of cytohistopathologic changes, mammary glands from 12 female cats were evaluated. The mean age of cats at the time of diagnosis was 11.5 ± 1.9 years (range 4–14 years), the mean gross size of the masses was 3.1 ± 2.4 cm, 4/12 (33.3 %) masses were ≤3.0 cm in diameter, and the maximum diameter of the largest mass had a median of 5 cm, with a range of diameter of 6 × 5 × 4 cm. Moreover, the preferential localization of mammary masses was the abdominal lobes (%50) and thoracic lobes (%33.3), and inguinal lobes (%16.7 of cases). Furthermore, two cases of the inguinal masses affected the caudo-inguinal lobe, six cases caudo-abdominal lobe, and thoracic masses were found in four cases. Eventually, six cases (%50) of masses were found in the right mammary lobes and six cases (%50) in the left mammary lobes. The majority of the masses revealed elastic (%50 of cases), hard (%25 of cases), or soft (%25 of cases) consistency. In the present study, according to the criteria of the veterinary and the medical WHO classification system, of the 12 cats with the cytohistopathological features of six (50 %) cases qualified abscess, 3 (25 %) cases as cystic hyperplasia and 3 (25 %) cases were called situ carcinoma. Whereas, all hyperplastic lesions (case nos. 7–9 and ranging in size from, 1 to >4 cm3) and carcinomas in situ lesions (case nos. 10–12 and ranging in size from, 1 to >3 cm3) were found incidentally upon routine cytohistology. Other lesions were observed grossly and removed either at surgery (case nos. 1–6). Finally, the cats were treated with unilateral lumpectomy (3 cases) and also, nine (75 %) cases had subsequent drainage, 3 (25 %) of which showed cystic hyperplasia and 6 (50 %) showed abscess on subsequent histopathological evaluation. Therefore, a correct diagnosis must be established quickly, and treatment must be instituted rapidly when alteration is noted in the mammary glands.

Temporal and spatial patterns of sediment routing across the southeast margin of the Tibetan Plateau: Insights from detrital zircon

AbstractThe Cenozoic deposits of the Tibetan Plateau's southeastern margin are often cited as part of a continental‐scale river system connecting the Paleo‐Yangtze River with the Paleo‐Red River. Confirming the purported connection and any subsequent drainage reorganization has garnered significant attention and varied proposed ages for reorganization. This study presents detrital zircon U‐Pb ages and paleocurrents in Eocene to Pleistocene sedimentary basin deposits distributed over a broad area of the southeast Tibetan Plateau margin within the area of proposed paleoriver connectivity. When combined with previously published studies, our U‐Pb ages allow examination of the temporal and spatial distributions of provenance throughout the Cenozoic. We identify six key age components of the detrital U‐Pb age distributions and use these to examine the patterns of sediment provenance for different Cenozoic epochs. Detailed analysis of these components shows that provenance for both onshore and offshore deposits is best described by local bedrock sources and provides little to no evidence of regional changes in provenance. This suggests that a stable fluvial system similar to the modern drainage network has existed since the Eocene with no evidence for major provenance‐altering river capture. Paleoflow measurements taken throughout the SE margin further corroborate the results of detrital zircon provenance. The combination of U‐Pb age components and paleocurrent directions does not support a Cenozoic connection between the Paleo‐Yangtze and Paleo‐Red Rivers.

Drainage mechanisms in porous media: From piston‐like invasion to formation of corner flow networks

AbstractWater drainage from porous media is a highly dynamic process often marked by rapid piston‐like air invasion events at the front and other rapid interfacial reconfigurations. Liquid phase entrapped behind the moving front drains at significantly slower rates often via gravity driven flow through corners and crevices. This distribution of slowly draining residual water phase determines the plant available water and biological functioning of soils. The study aims to determine the conditions for the flow regime transition from piston‐like invasion at a drainage front to slower corner dominated flow at the pore and sample scale. This transition was observed experimentally for sand and glass beads with fast X‐ray tomography, revealing water fragmentation into clusters of full pores interconnected by water corner films. The observed liquid morphology at the transition from piston to corner flow was reproduced by a quasi‐static pore network model and predicted by percolation theory. The amount of capillary‐retained water at flow transition controlling the subsequent drainage dynamics could be reproduced by an idealized star shaped pore whose geometry is deduced from macroscopic properties of the porous medium. Predictions of water content thresholds at flow transitions were in agreement with other critical saturation values associated with cessation of solute diffusion and of internal drainage (at field capacity) highlighting the criticality of water phase continuity disruption for formation of relatively stable unsaturated conditions controlled by slow corner flow that support life in soil.

Periampullary Diverticular Food Impaction: A Rare Cause of Obstructive Jaundice

Periampullary diverticula (PAD) are extra-luminal outpouchings of the duodenum arising within a radius of 2-3 cm from the ampulla of Vater. The prevalence of PAD increases with age and reaches up to 27% in elderly patients. We present a case where food impaction of a PAD caused biliary obstruction and its subsequent management. 86-year-old male with no significant gastrointestinal history presented with a 4 day history of painless jaundice. Physical exam revealed scleral icterus and cutaneous jaundice but was negative for hepatosplenomegaly or abdominal tenderness. Labs revealed AST 98, ALT 133, ALP 1204, total bilirubin 7.6 and direct bilirubin 6.9. CT abdomen revealed biliary ductal dilatation up to 2 centimeters with tapering at the ampulla and distal obstruction. MRCP revealed severe intra- and extrahepatic biliary ductal dilation and a T2 hypointense and T1 hyperintense mass adjacent to the distal common bile duct (CBD) near the pancreatic head. The patient underwent EGD with a side-viewing duodenoscope and EUS which revealed a dilated CBD without stones or hypoechoic mass. Instead, he was noted to have a large PAD with its lumen completely occluded by retained food. This was visualized as a round hyperechoic lesion on EUS. The major papilla could not be located, presumably located inside the PAD. A variety of endoscopic methods were then used to disimpact the debris, including rat tooth forceps, sphinctertome and water irrigation without much success. Eventually, carbonated beverage was injected through a sphinctertome into the diverticulum allowing for successful removal of debris and subsequent bilious drainage from the CBD. Following the procedure, the patient's transaminases and bilirubin normalized and he was safely discharged home. He continued to do well 3 months after treatment.Figure 1Figure 2Periampullary diverticula are associated with age and can be found in up to 27% of elderly patients. The clinical importance of these usually stems from the fact that cannulation during ERCP can be difficult in patients with anatomical distortion due to large PAD or when the papilla is located inside a diverticulum. Patients with PAD also have a higher incidence of choledocholithiasis. Our case demonstrates a rare cause of biliary obstruction where a PAD became occluded by food debris, eventually leading to painless jaundice mimicking malignancy. The case also highlights the utility of carbonated beverage in successfully resolving the occlusion.

Evaluation of event-based irrigation system control scheme for tomato crops in greenhouses

This work presents a study and evaluation of an event-based predictive control system for a greenhouse irrigation process. The control system objective is to maintain the desired substrate humidity level, keeping the water usage as low as possible. The event-based control scheme uses a crop transpiration model to determine the volume of water required to compensate for the irrigation system and a water content model to trigger the irrigation system events. First, simulation experiments were performed to analyze the behavior of the designed system and to study the water supply dynamics to the substrate and subsequent drainage and evaporation. Secondly, the proposed event-based controller was evaluated in an experimental greenhouse, located in southeast of Spain, in real operation conditions. The resulting control system is able to adapt the actuation rate to the state of the plant providing the efficient way of water consumption. The obtained results show that the application of proposed event-based approach for the greenhouse irrigation system allows to improve the control performance and to reduce the water usage (about 20% of required water for the same performance obtained for commonly used on/off) being an important issue in intensive agriculture. The improved control performance is obtained due to event-based approach and the inclusion of information about the plant dynamic response for water supply and transpiration effect.

Timing of Antibiotic Prophylaxis for Preventing Surgical Site Infections in Foot and Ankle Surgery

Category: Other Introduction/Purpose: Surgical site infection (SSI) is one of the most troublesome outcomes after any surgery, for both patient and surgeon. In addition to significant morbidity for patients, SSIs have been hallmarked as an important metric in value-based purchasing by CMS. Surgical literature has suggested that 15-60 minutes prior to incision is the ideal timing of intravenous antibiotics. The purpose of this study is to find the optimal timing of antibiotic administration before foot and ankle surgery, as well as to elucidate the risk factors for SSIs. Methods: An a priori power analysis was performed in order to detect a 4% absolute increase in infection rate with delayed timing of antibiotic prophylaxis, based on a presumed baseline SSI rate of 4% in foot and ankle surgeries based on literature on healthy patients undergoing foot and ankle surgery (n=1204 to achieve a power of .80). A retrospective chart review of 1933 foot and ankle procedures in 1632 patients over 56 months was performed. Demographic data, type and amount of antibiotics, timing of antibiotic administration, incision time, and closure time were recorded. The incidence of subsequent wound infection and subsequent incision and drainage procedure (I&amp;D) within 30 days and 90 days were documented. Comparison of outcomes and demographic variables between the group of patients who received preoperative antibiotics less than 15 minutes before incision, and those who received them between 15 to 60 minutes prior to incision was performed. Results: A total of 1569 procedures met inclusion criteria. There were a total 17 cases (1.1%) of subsequent wound infection, of which 11 required a subsequent I&amp;D within 90 days. There were 59 additional cases (3.8%) of wound complications which did not meet SSI criteria. When antibiotics were administered between 15 and 60 minutes prior to incision, there was a 2.7-fold, statistically significant higher rate of SSIs as compared to the group of patients receiving antibiotics &lt; 15 minutes before incision (p &lt; 0.05). When comparing the patients who had subsequent SSIs to those who did not, the only significant independent predictors were longer surgeries and non-ambulatory surgeries (both p &lt; 0.05). When a stepwise multivariate logistic regression was performed to see which variables would predict an SSI, it was found that 91.8% of the risk of an SSI could be predicted by ASA score and length of surgery alone. Conclusion: In foot and ankle surgeries, the timing of intravenous antibiotic prophylaxis does not appear to play as large of a role as in other surgical subspecialties. Our studies revealed that host factors length/complexity of surgery may play a much larger role in determining the rate of infections than the timing of antibiotic prophylaxis.

Asymmetric bursting of Taylor bubble in inclined tubes

In the present study, experiments have been reported to explain the phenomenon of approach and collapse of an asymmetric Taylor bubble at free surface inside an inclined tube. Four different tube inclinations with horizontal (30°, 45°, 60° and 75°) and two different fluids (water and silicon oil) are considered for the experiment. Using high speed imaging, we have investigated the approach, puncture, and subsequent liquid drainage for re-establishment of the free surface. The present study covers all the aspects in the collapse of an asymmetric Taylor bubble through the generation of two films, i.e., a cap film which lies on top of the bubble and an asymmetric annular film along the tube wall. Retraction of the cap film is studied in detail and its velocity has been predicted successfully for different inclinations and fluids. Film drainage formulation considering azimuthal variation is proposed which also describes the experimental observations well. In addition, extrapolation of drainage velocity pattern beyond the experimental observation limit provides insight into the total collapse time of bubbles at different inclinations and fluids.

High-pressure air blasting experiments on concrete and implications for enhanced coal gas drainage

High-pressure air blasting is one type of destress blasting techniques to enhance gas drainage in coal seams and thus to prevent coal and gas outbursts. In this work, firstly, high-pressure air blasting experiment is conducted on concrete specimen with a size of 600 mm × 600 mm × 600 mm, the blasting crack distribution is observed and the particle vibration acceleration at the outer boundary of the sample is monitored. Then a damage model for high-pressure air blasting is proposed when the loading induced by high-pressure air blasting is considered as two consecutive stages, i.e. the dynamic loading stage induced by the stress wave and the quasi-static loading stage induced by quasi-static air pressure. Based on the experimental curve of particle vibration acceleration and corresponding numerical simulation, the stress wave distribution with Gaussian form around the hole is inversed. In addition, the blasting induced damage evolution in the concrete specimen is numerically simulated, and the numerical result of final cracking pattern compares favorably with the experimental observation. During the high-pressure air blasting on concrete block, the blasting stress wave initiates primarily radial cracks and the crushed zone, and the quasi-static air pressure results in the extension of existing cracks and the expansion of crushed zone. Compared to the hydraulic fracturing with water, the high-pressure air blasting induces more fractures, which would be of great benefit to the enhanced gas drainage in coal seam. Finally, by considering the effect of coal seam damage on permeability, the gas drainage that may be enhanced by high-pressure air blasting is quantified based on the numerical simulations. It is demonstrated the damage induced by high-pressure air blasting around the hole enhances the gas drainage dramatically; however, the in-situ stress in coal seam may restrain the blasting-induced fractures and subsequent gas drainage, which should be paid attention to during the design of enhanced gas drainage with high-pressure air blasting.