bluuebunny/crossref_metadata_2025_split huggingface dataset:
Choosing the legal retirement age in presence of unemployment
Authors: Casamatta Georges , De Paoli Caroline 
Published: April 2012

Résumé La littérature théorique sur les retraites conclut que, dans une situation où la longévité augmente, les individus devraient travailler plus longtemps. Dans cette article, nous cherchons à déterminer si cette conclusion est toujours valide lorsque les individus font face au risque de chômage. Dans cette optique, nous étudions le choix du système de retraite par répartition, en mettant l’accent sur l’âge de départ en retraite, dans un modèle où les individus diffèrent par leur âge seulement et font face au risque de chômage. Nous déterminons dans un premier temps le système de retraite optimal, ce système étant caractérisé par le taux de cotisation, le niveau de prestation et l’âge de la retraite et nous étudions la statique comparative par rapport au taux de chômage et la durée de vie. Nos résultats principaux sont les suivants. Tout d’abord, il est optimal de différer l’âge de la retraite lorsque la durée de vie augmente. Ensuite, nous trouvons que l’âge de la retraite optimal peut diminuer lorsque le risque de chômage augmente. Nous caractérisons enfin l’équililibre de vote et le comparons avec le système optimal. Nous montrons que l’électeur médian choisit en général un âge de la retraite inférieur à l’âge optimal ainsi qu’un taux de cotisation plus important. Classification JEL : H55
Gastrointestinal endoscopy- An emerging soft power in health care
Authors: Rao G. V. , Mansard Magnus , Reddy D. N. 
Published: April 2012

Abstract“Soft power” is a relatively new concept that describes an entity’s ability to influence and alter the behavior of other entities through attraction and co-option, in contrast to hard power which uses incentives and coercion. Assessment of the role of GI GI (Gastrointestinal) Endoscopy in present day’s health care shows it to have the required attractive and influential properties of a soft power. In this article we examine the diagnostic and therapeutic roles that GI endoscopy, as a soft power, has taken over, and the further evolution of this field into a smart power.
Advances in endoscopic imaging: Advantages and limitations
Authors: Banerjee Rupa , Reddy D. Nageshwar 
Published: April 2012

AbstractEndoscopic imaging is emerging beyond the confines of traditional white light endoscopy. There is a plethora of advanced imaging technologies which aim to improve visualization of the vascular network and surface texture of the mucosa and thereby improve tissue characterization, differentiation, and diagnosis. These include the wide field technologies like chromoendoscopy, narrow band imaging and autofluorescence endoscopy and point enhancement or virtual histology technologies like endocytoscopy and confocal endomicroscopy. This review attempts to define the current status of these newer technologies and the advantages and limitations in current clinical practice.
Diagnostic and therapeutic peroral cholangioscopy
Authors: Moon Jong Ho , Seo Yu Ri , Choi Hyun Jong 
Published: April 2012

AbstractPeroral cholangioscopy (POC) provides direct visualization of the bile duct and facilitates diagnostic or therapeutic intervention. The currently available single-operator POC systems are “Mother-baby” scope system, SpyGlass direct visualization system, and direct POC using a regular ultra-slim upper endoscope. Direct POC using an ultra-slim upper endoscope having a larger 2-mm working channel can provide a valuable and economic solution for evaluating bile-duct lesions. Main diagnostic procedures under direct POC are visual characterization and optically guided target biopsy for the indeterminate bile duct lesion. Image-enhanced endoscopy such as narrow-band imaging has shown promise for more detailed evaluation of mucosal abnormality and can be performed under direct POC. Intracorporeal lithotripsy such as electrohydraulic lithotripsy or laser lithotripsy is a main therapeutic intervention of direct POC for patients with bile duct stones that are resistant to conventional endoscopic stone-removal procedures. Besides, tumor ablation therapy, such as photodynamic therapy and argon plasma coagulation may be also performed using direct POC. Further developments of the endoscope and specialized accessories or devices are expected to facilitate diagnostic and therapeutic role of this cholangioscopic procedure.
Postcholecystectomy benign biliary stricture: Surgery is the gold standard
Authors: Sikora Sadiq S. 
Published: April 2012

AbstractPost cholecystectomy bile duct strictures present a challenge to the treating physicians. Advancement in skills and technology offers alternative treatment modalities to the standard surgical repair. Contemporary series of surgical repair by experienced surgeons report excellent long-term results with <5% restricture rates. Endoscopic therapy is conceptually flawed, is not applicable to all patients, requires prolonged duration of treatment with multiple interventions. Surgical repair by an experienced surgeon is the “Gold Standard” of care in management of postcholecystectomy bile duct strictures.
Critical evaluation of pancreatic masses
Authors: DeWitt John 
Published: April 2012

AbstractEvaluation of a patient with a pancreatic mass on a CT or MRI requires consideration of the gender and age of the patient, presenting symptoms, quality of the imaging study performed and relevant medical history. CT is generally preferred over MRI for suspected pancreatic cancer but MRI is best considered for evaluation of ductal anatomy and possible cystic neoplasms. EUS should be considered when further characterization of morphology or tissue sampling is required.
Management of chronic pancreatitis: Role of endoscopic therapy
Authors: Tandan Manu , Reddy D. Nageshwar 
Published: April 2012

AbstractChronic pancreatitis (CP), a disease of varied etiology can, from the endoscopists perspective present as ductal strictures, stones, ductal leaks and fluid collections, biliary strictures or duodenal narrowing. This article deals with role of ERCP in the management of CP associated strictures and calculi. ERCP has a limited role in the diagnosis CP, though we feel that it is better at identifying small ductal calculi or leaks as compared to MRCP. Major and minor papilla sphincterotomy gives relief from pain in patients with mild or moderate ductal changes. Pancreatic ductal strictures are best managed by stenting. Use of multiple plastic stents (8.5-11Fr diameter) gives relief from pain in 84% and strictures resolution in 95% on follow up of over 3 years. CP associated CBD strictures are also managed by placement of multiple stents. Covered SEMS are increasingly being used in these strictures. Surgery is often the best option for CP associated CBD strictures which recur after adequate endotherapy. ESWL is the standard of therapy for pancreatic ductal calculi which are large, as seen in the tropics and the non alcoholic form of CP. Our experience has shown complete or partial clearance with ESWL in over 90% of patients with large PD calculi. Good pain relief was seen in both on short and long term follow up. In selected patients of CP, ERCP and endotherapy should be offered as first line of treatment, as the results are comparable to surgery. Prior endotherapy also does not interfere with subsequent surgical procedures.
Endoscopic management of pancreatic pseudocysts
Authors: Varadarajulu Shyam 
Published: April 2012

AbstractThe conventional management of pancreatic pseudocysts involves surgery or percutaneous drainage. While surgery is associated with significant complications and mortality, percutaneous drainage is associated with prolonged hospitalization and often times the need for other adjunctive treatment measures. Therefore, the use of endoscopy to drain these pseudocysts is becoming increasingly popular. In this review, we will be examining the techniques, outcomes and costs associated with the endoscopic drainage of pancreatic pseudocysts.
Capsule endoscopy: Beyond small bowel
Authors: Adler Samuel N. 
Published: April 2012

AbstractIn this article the brief and dramatic history of capsule endoscopy of the digestive tract is reviewed. Capsule endoscopy offers a non invasive method to diagnose diseases that affect the esophagus, small bowel and colon. Technological improvements relating to optics, software, data recorders with two way communication have revolutionized this field. These advancements have produced better diagnostic performance.
Engineering of Oriented Myocardium on Three-Dimensional Micropatterned Collagen-Chitosan Hydrogel
Authors: Chiu Loraine L.Y. , Janic Katarina , Radisic Milica 
Published: April 2012

Introduction: Surface topography and electrical field stimulation are important guidance cues that aid the organization and contractility of cardiomyocytes in vivo. We report here on the use of these biomimetic cues in vitro to engineer an implantable contractile cardiac tissue. Methods: Photocrosslinkable collagen-chitosan hydrogels with microgrooves of 10 μm, 20 μm and 100 μm in width were fabricated using polydimethylsiloxane (PDMS) molds. The hydrogels were seeded with cardiomyocytes, placed into a bioreactor array with the microgrooves aligned with the electrical field lines, and stimulated with biphasic square pulses at 1 Hz and 2.5 V/cm. Results: At Day 6, cardiomyocytes were aligned in the direction of the microgrooves. When cultivated without electrical stimulation, the excitation threshold of engineered cardiac tissues using micropatterned hydrogels was significantly lower than using smooth hydrogels, thus showing the importance of cell alignment to cardiac function. The success rate of achieving beating constructs was higher with the application of electrical stimulation. In addition, formation of dense contractile cardiac organoids was observed in groups with both biomimetic cues. The cultivation of cardiomyocytes on hydrogels with 10 μm grooves yielded 100% beating tissues with or without electrical stimulation, thus suggesting a smaller groove width is necessary for cells to communicate and form proper gap junctions. However, electrical field stimulation further increased cell density and enhanced tissue morphology which may be essential for the integration of the tissue construct to the native heart tissue upon implantation. Conclusions: The biodegradability of the hydrogel substrate allows for the rapid translation of the engineered, oriented cardiac tissue to clinical applications.
Development of Artificial Neural Network–Based Algorithms for the Classification of Bileaflet Mechanical Heart Valve Sounds
Authors: Bagno Andrea , Licciardello Claudia , Tarzia Vincenzo , Bottio Tomaso , Pengo Vittorio , Gerosa Gino 
Published: April 2012

Objectives: As is true for all mechanical prostheses, bileaflet heart valves are prone to thrombus formation; reduced hemodynamic performance and embolic events can occur as a result. Prosthetic valve thrombosis affects the power spectra calculated from the phonocardiographic signals corresponding to prosthetic closing events. Artificial neural network–based classifiers are proposed for automatically and noninvasively assessing valve functionality and detecting thrombotic formations. Further studies will be directed toward an enlarging data set, extending the investigated frequency range, and applying the presented approach to other bileaflet mechanical valves. Methods: Data were acquired for the normofunctioning St. Jude Regent valve mounted in the aortic position of a Sheffield Pulse Duplicator. Different pulsatile flow conditions were reproduced, changing heart rate and stroke volume. The case of a thrombus completely blocking 1 leaflet was also investigated. Power spectra were calculated from the phonocardiographic signals and used to train artificial neural networks of different topologies; neural networks were then tested with the spectra acquired in vivo from 33 patients, all recipients of the St. Jude Regent valve in the aortic position. Results: The proposed classifier showed 100% correct classification in vitro and 97% when applied to in vivo data: 31 spectra were assigned to the right class, 1 received a false positive classification, and 1 was “not classifiable.” Conclusion: Early malfunction detection is necessary to prevent thrombotic events in bileaflet mechanical heart valves. Following further clinical validation with an extended patient database, artificial neural network–based classifiers could be embedded in a portable device able to detect valvular thrombosis at early stages of formation: this would help clinicians make valvular dysfunction diagnoses before the appearance of critical symptoms.
TANQUA KAROO, ANCIENT ANALOG FOR FINE-GRAINED SUBMARINE FANS
Authors: BOUMA ARNOLD H. , WICKENS H. DEVILLE 
Published: April 2012

ABSTRACT
The Permian Tanqua subbasin in the southwestern Karoo Basin, South Africa, contains five basin-floor fans and one slope fan. The total outcrop area is about 650 km in size; the individual outcropping fans range in size from about 150 km2 to 450 km2. The arenaceous fans have a high sandstone/shale ratio of about 75-90%, range in individual thickness from 20-60 m, and are separated by 20-75m thick basin shales.
Deposition of each fan is in response to a 4th-order, tectonically controlled relative sea-level lowering within a 3rd order transgressive systems tract.
Two basin-floor fans show mid-fan channel complexes with levee-overbank deposits which change in downdip direction into non-channelized, sheet-like outer fan depositional lobes. Simultaneously, the sandstone/shale ratio increases in the same direction. The other three basin-floor fans contain outer fan depositional lobes.
Four of the basin-floor fans show paleocurrent directions from SSW and S, whereas one was fed from the W-WNW. Absence of folding provides ideal lateral correlation; cliff-type outcrops occur over a distance of 34 km. Three 8-12 km long E-W outcrops with only minor regional tilt complete the major data source. A channel complex, assumed to be deposited at the base-of-slope, is found in the most proximal area. The complex comprises both large and small, rather shallow, channel fills with erosional contacts and remnants of probable thin-bedded levees. The single channels are embedded in thin-bedded turbidite series; some are connected physically to the channel fill. Such levee deposits can be composed of very clean sands with thin shales, and have well-developed cross bedding and climbing ripples. They show a significant issuing angle (25-35°) in paleocurrent direction from the channel.
The sheet sands comprise bundles of 6-8 very flat, often amalgamated, lenticular sandstone beds. The amalgamated contacts change laterally into thin shales. Sheet sand bundles are slightly lenticular which is extremely difficult to discern on cursory examination of photo-mosaics of long outcrops, but can be demonstrated by careful bed tracing.
The long outcrops make it possible to collect field data required to 1) improve our understanding of the overall architecture of fine-grained, “low” sandstone/shale ratio submarine fans, and 2) to carry out detailed reservoir simulation programs.
SHELF PROCESSES AND CANYON/CHANNEL EVOLUTION CONTROLLING TURBIDITE SYSTEMS: EXAMPLES FROM THE SERGIPE-ALAGOAS BASIN, BRAZIL
Authors: Cainelli Cesar 
Published: April 2012

ABSTRACT
An industrial data set (seismic sections, well logs, and cores), extending to a water depth of 3,000 m, provided the opportunity to conduct an integrated stratigraphic analysis among shelf, slope, and basin depositional environments. The study focused on a 3,000-m seaward-thickening prograding wedge, subdivided into four sequences. The high energy shelf, dominated by waves and currents, produced mature sands mixed seaward with carbonates that border the shelf edge. Basinward, a thick section of shales was developed contemporaneously. Canyon systems on the sequence boundaries acted as routes through the shelf carbonate rims in the development of deep-water turbidite systems. The timing for down-slope transport of shelf sands was controlled by the evolution of few canyons from immature to mature. Mature canyons that entrenched deeply onshoreward tapped the sands dammed by shelf-edge carbonates. Sands funneled downcanyon were concentrated into isolated or migrating leveed channels as coarsegrained lags of turbidite systems distributed in time and space into the thick slope apron.
FACIES ARCHITECTURE AND RESERVOIR CHARACTERIZATION OF A SUBMARINE FAN CHANNEL COMPLEX, JACKFORK FORMATION, ARKANSAS
Authors: Cook Timothy W. , Bouma Arnold H. , Chapin Mark A. , Zhu Hua 
Published: April 2012

ABSTRACT
The upper Pennsylvanian Jackfork Formation is exposed at the 900 m (2750 ft) wide by 60 m (200 ft) high wall of Big Rock Quarry, in North Little Rock, Arkansas. At this location, the formation provides a strike section view of a sand-rich submarine fan, comprising laterally imbricated and crosscutting channels. Geological heterogeneity within the nested submarine fan channel complex was described qualitatively to note architectural characteristics not usually observed in outcrops due to limited scale of exposure. Field reconaissance and photographic studies revealed a variety of channel fill types in the overall exposure, with amalgamated massive sandstone fill as the dominant lithology.
Architectural drawings of the quarry, made from enlarged photographic prints, were digitized and analyzed using a Shell software package with the intent of translating outcrop-based observations into useful parameters for subsurface reservoir models. The analysis revealed that 1) the facies distribution calculated during the statistical analysis compares favorably to the facies distribution in a core taken 15 m (50 ft) behind the face of the outcrop; 2) no discrete, recognizable beds are continuous across the 900 m (2750 ft) strike-oriented exposure; 3) maximum well spacing (along strike) for a dual production well scenario is approximately 1.6 km (1 mi); and 3) maximum well spacing for an injection-production (water-flood) well plan is approximately 300 m (1000 ft).
SUBMARINE FANS ON THE NORTHEASTERN GRAND BANKS, OFFSHORE NEWFOUNDLAND
Authors: DESILVA NEIL R. 
Published: April 2012

ABSTRACT
The northeastern Grand Banks of Newfoundland is underlain by the Jeanne d’Arc Basin and the Outer Ridge. To date, twelve significant hydrocarbon accumulations, including the giant Hibernia oil field, have been discovered in the basin and three have been discovered on the Outer Ridge. Some of these discoveries are in submarine fans.
The submarine fans on the northeastern Grand Banks can be grouped into four categories based on their age: 1) Late Jurassic submarine fans, derived from highlands to the south, 2) Early Cretaceous submarine fans, related to progradation of deltas of the Hibernia Formation; 3) Late Cretaceous submarine fans, associated with a major clastic wedge that prograded from the western margin of the basin; 4) Early Tertiary basin floor fans and slope fans related to a major sea level lowstand.
Hydrocarbons have been encountered in all four groups of submarine fans. With only about 10% of the potential recoverable oil in the basin discovered so far (McAlpine 1990), they could provide promising drilling targets.
FACIES ARCHITECTURE AND RESERVOIR QUALITY OF MIOCENE MT. MESSENGER DEEP-WATER DEPOSITS, TARANAKI PENINSULA, NEW ZEALAND
Authors: JORDAN DOUGLAS W. , SCHULTZ DOUGLAS J. , CHERNG J. ALBERT 
Published: April 2012

The Mt. Messenger Formation exposed along the coastline of the Taranaki Peninsula contains flat-laminated, very-fine to fine-grained sands inlerbedded with bioturbated silt and silty claystone. These beds are typically over 5 cm thick and are the result of high-velocity turbidity currents which allow for good textural sorting and preservation of excellent reservoir-quality sands. Beds less than this thickness, as well as upper parts of many turbidites, typically contain features suggesting reworking, winnowing, and remolding by bottom currents. This winnowing effect is responsible for the good to excellent reservoir properties of the thin, poorly consolidated, well-sorted, very fine-grained lithic arenites. Mt. Messenger sands were deposited on a depositional slope in lower to upper bathyal water depths which was the site for these transforming bottom currents.
The Mt. Messenger overlies Mohakatino, Ferry, and Tawariki sandstones and siltstones which were the initial deepwater sediments in the basin. These sandstones are lithic-rich and fine to medium-grained. The beds are typically massiveappearing but locally contain dewatering features, typical ‘classic’ turbidites (graded beds, slurry or low-density turbidity current tops), and were deposited as thick sheet-like bodies on the basin floor. Winnowing of the sandstones did not take place on a large scale and hence reservoir quality is invariably poor to moderate.
The mica stilpnomelane in the sands is common; this mineral is restricted areally to low-grade regionally metamorphosed sediments and associated veins, most notably to the schists of western Otago, New Zealand, on the northwestern part of the south island The occurrence of this mineral has important implications as to the source of the Mt. Messenger sediments in the North Taranaki area (transport was from south to north from the South Island).
RESERVOIR CLASSIFICATION FOR TURBIDITE INTERVALS AT THE MARS DISCOVERY, MISSISSIPPI CANYON 807, GULF OF MEXICO
Authors: Mahaffie M.J. 
Published: April 2012

Abstract
A descriptive reservoir classification was used to characterize the turbidite sands encountered at Prospect Mars, a significant Gulf of Mexico deep water oil discovery made under joint partnership with Shell Offshore Incorporated and British Petroleum Incorporated. External reservoir geometries observed from seismic data and internal fill characteristics from wireline logs and whole core form the basis for subdividing turbidite sands into three major categories: 1) thin-bedded channel levee and overbank sediments, 2) channel-fill complexes, and 3) sheet sands. This classification scheme was implemented to link the various scales of investigation obtained from the subsurface with details of reservoir architecture determined from turbidite outcrop studies. In this manner, characteristics of sand continuity and connectivity at the outcrop scale can be incorporated with observations from seismic and well control toward more accurately predicting reservoir performance and field development strategy.
Depositional models were constructed for each significant turbidite sand package using this reservoir classification. The majority of reservoirs are described as sheet sands. Minor portions of the basin fill represent channel-fill complexes. Three depositional models are presented to illustrate the style of deposition at Mars and the utility of this classification scheme. Development drilling is currently underway using these depositional models as a framework for field exploitation.