bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction networks in coastal soft‐sediments highlight the potential for change in ecological resilience
Authors: Thrush S. F. , Hewitt J. E. , Lohrer A. M.
Published: January 2012

Recent studies emphasize the role of indirect relationships and feedback loops in maintaining ecosystem resilience. Environmental changes that impact on the organisms involved in these processes have the potential to initiate threshold responses and fundamentally shift the interactions within an ecosystem. However, empirical studies are hindered by the difficulty of designing appropriate manipulative experiments to capture this complexity. Here we employ structural equation modeling to define and test the architecture of ecosystem interaction networks. Using survey data from 19 estuaries we investigate the interactions between biological (abundance of large bioturbating macrofauna, microphytobenthos, and detrital matter) and physical (sediment grain size) processes. We assess the potential for abrupt changes in the architecture of the network and the strength of interactions to occur across environmental gradients. Our analysis identified a potential threshold in the relationship between sediment mud content and benthic chlorophyll a, at ∼12 μg/g, using quantile regression. Below this threshold, the interaction network involved different variables and fewer feedbacks than above. This approach has potential to improve our empirical understanding of thresholds in ecological systems and our ability to design manipulative experiments that test how and when a threshold will be passed. It can also be used to indicate to resource managers that a particular system has the potential to exhibit threshold responses to environmental change, emphasizing precautionary management and facilitating a better understanding of how persistent multiple stressors threaten the resilience and long‐term use of natural ecosystems.
Marine reserves reduce risk of climate‐driven phase shift by reinstating size‐ and habitat‐specific trophic interactions
Authors: Ling S. D. , Johnson C. R.
Published: January 2012

Spatial closures in the marine environment are widely accepted as effective conservation and fisheries management tools. Given increasing human‐derived stressors acting on marine ecosystems, the need for such effective action is urgently clear. Here we explore mechanisms underlying the utility of marine reserves to reinstate trophic dynamics and to increase resilience of kelp beds against climate‐driven phase shift to sea urchin barrens on the rapidly warming Tasmanian east coast. Tethering and tagging experiments were used to examine size‐ and shelter‐specific survival of the range‐extending sea urchin Centrostephanus rodgersii (Diadematidae) translocated to reefs inside and outside no‐take Tasmanian marine reserves. Results show that survival rates of C. rodgersii exposed on flat reef substratum by tethering were approximately seven times (small urchins 10.1 times; large urchins 6.1 times) lower on protected reef within marine reserve boundaries (high abundance of large predatory‐capable lobsters) compared to fished reef (large predatory lobsters absent). When able to seek crevice shelter, tag‐resighting models estimated that mortality rates of C. rodgersii were lower overall but remained 3.3 times (small urchins 2.1 times; large urchins 6.4 times) higher in the presence of large lobsters inside marine reserves, with higher survival of small urchins owing to greater access to crevices relative to large urchins. Indeed, shelter was 6.3 times and 3.1 times more important to survival of small and large urchins, respectively, on reserved relative to fished reef. Experimental results corroborate with surveys throughout the range extension region, showing greater occurrence of overgrazing on high‐relief rocky habitats where shelter for C. rodgersii is readily available. This shows that ecosystem impacts mediated by range extension of such habitat‐modifying organisms will be heterogeneous in space, and that marine systems with a more natural complement of large and thus functional predators, as achievable within no‐take reserves, will minimize local risk of phase shifts by reinstating size and habitat‐specific predator–prey dynamics eroded by fishing. Importantly, our findings also highlight the crucial need to account for the influence of size dynamics and habitat complexity on rates of key predator–prey interactions when managing expectations of ecosystem‐level responses within marine reserve boundaries.
Effects of VTI Anisotropy on Shale Reservoir Characterization
Authors: Banik Niranjan , Egan Mark
Published: January 2012

Presently shale reservoirs are the one of the hottest plays in the oil industry. Our understanding of these reservoirs rapidly progressed from one of a continuous type, to that of a spatially varying type. Two key elastic parameters, Young’s modulus and Poisson’s ratio are critically relied upon, to seismically high-grade these spatially varying reservoirs in terms of their reservoir and completion qualities. Isotropic elastic properties are assumed in the delineation of ‘frac’able’ zones and sweet spots. However, these shale formations are highly anisotropic even in the absence of any in-situ fractures and there are multiple Young’s moduli and Poisson’s ratios in an anisotropic medium.

In this paper we discuss the effects of vertical transverse isotropy (VTI) in characterizing shale reservoirs in terms of Young’s moduli and Poisson’s ratios. We begin by rewriting Young’s modulus and Poisson’s ratio formulae in terms of Thomsen’s anisotropy parameters (Thomsen,1986). Both approximate and exact expressions are given. Approximate relations in terms of anisotropy parameters are easier to interpret than those in terms of the stiffness coefficients. We then discuss the results in terms of relevant ranges of values of these anisotropy parameters. Also, an important contribution to fracture initiation and containment comes from the uniaxial stress ratio (Higgins et al., 2008;Sayers, 2010, Iverson, 1995). It is the ratio of the horizontal to the vertical stresses in the absence of any transverse strain. The effects of anisotropy on the uniaxial stress ratio are discussed in this context. Finally we discuss how P-wave surface seismic data can be integrated with borehole and other measurements to estimate relevant elastic attributes in these highly anisotropic shale formations.
New Hydraulic-Fracturing Process Enables a Low-Risk, Operationally Efficient Solution While Maximizing Stimulation Effectiveness in Unconventional Reservoirs
Authors: Beaman Daniel , McNeil Fraser
Published: January 2012

Technological advances and improved operational efficiency have made unconventional resources around the globe far more lucrative for producers. The challenge in recovering hydrocarbons from unconventional resources is low permeability, making it essential that a cost-efficient fracture-stimulation treatment program be performed. However, while the wells being completed are economical, are operators truly capitalizing on their full potential?

The process of fracturing unconventional reservoirs has remained virtually unchanged in recent years. Stimulation treatments are pumped at high rates through multiple perforation clusters over a large interval and isolated using mechanical plugs. This poses several problems: Uncertainty of the number of fractures created.Uncertainty of proppant placement into fractures.Costly and time-consuming recovery from screenouts.Pumping plugs results in overflushing the near-wellbore.Treatment changes cannot be seen at the perforations until a casing volume is pumped.Increased cost, footprint, personnel, and hydraulic-horsepower (HHP) requirements.

This paper presents a high-rate coiled tubing (CT) fracturing technique that enables customized fracture treatments to help maximize stimulated reservoir volume (SRV) by manipulating flow rate and proppant concentration at the perforations in response to reservoir pressure. Therefore, every gallon of fluid and every pound of proppant can be used to effectively stimulate the formation. Recovery from screenouts is fast because of having coil in-hole, but the functionality of the process enables screenouts to be avoided all together. At the end of the treatment, the well is simply cleaned out, and the entire operation is completed with only one trip in hole and with no plugs to be drilled out. These benefits combined can maximize return on investment for the operator. This paper includes a side-by-side comparison of this technique with a conventional fracturing treatment, weighing risk, stimulation effectiveness, operational efficiencies, and cost savings.
Effect of Sand Lens Size and Hydraulic Fractures Orientation on Tight Gas Reservoirs Ultimate Recovery
Authors: Kantanong Narisara , Bahrami Hassan , Rezaee Reza , Hossain Mofazzal , Nasiri Amir
Published: January 2012

Low permeability and complexities of rock formation in tight gas resources make it more complicated to predict well production performance and estimate gas recovery. To produce from the unconventional resources in the case that formation rock is not sensitive to damage caused by liquid invasion, hydraulic fracturing is the most common stimulation treatment to improve the production to the excepted economically rate.

In term of reservoir geometry, tight sand formations are normally stacks of isolated lenses of sand bodies that are separated by shale layers. Each sand lens varies in shape and size and acts as a trap for original hydrocarbon accumulations. The sand lenses parameters such as length and width can play important role in controlling gas recovery from hydraulically fractured tight gas reservoirs.

This study shows the effect of drainage pattern of the lenticular sand bodies on production performance and ultimate gas recovery in tight gas formations. Analytical and numerical simulation approaches are used in order to understand the effect of hydraulic fracture parameters and also attribution of sand lens size and shape to the drainage pattern and gas recovery in hydraulically fractured tight sand gas reservoirs.

The results highlighted that in tight gas with massive hydraulic fractures, sand lens size in the direction perpendicular to hydraulic fracture wings has the major impact on gas recovery. Sand lens size in the direction parallel to hydraulic fracture wings does not have significant effect on gas recovery. When the sand lenses are isolated and small in size, from a singlewell-enhancement perspective, the gas recovery will increase significantly by performing massive hydraulic fracturing through isolated lenses.
Pinpoint-Fracturing Technology Improves Efficiencies While Solving Issues with Conventional Hydraulic-Fracturing Processes
Authors: Chellani Divesh , Gurnito Nuratas , Ables Colt
Published: January 2012

This paper discusses issues encountered by an operating company in West Bengal, India and how technological, operational, and engineering solutions were applied to resolve them. The goal was to complete a well with only one coiled tubing (CT) trip while placing several pinpoint hydraulic fractures, thus increasing efficiency. The solution entailed using hydrajet perforating combined with annular pumping and proppant plugs for diversion.
The Recent Applications of Jet Pump Technology to Enhance Production from Tight Oil and Gas Fields
Authors: Sarshar Sacha
Published: January 2012

Production from many oil and gas fields becomes restricted as the reservoir pressure drops. The situation becomes worse for fragmented reservoirs and tight reservoirs, when water-cut also increases. In order to maintain production at an economical rate, and also to increase total recovery from the field, a production boosting system is always required.

Jet pumps are simple passive devices which use a high pressure (HP) fluid as the motive flow to boost the pressure of produced gas and liquid phases. For producing wells; it enables the flowing wellhead pressure (FWHP) to be reduced in order to increase production, whilst meeting the downstream production pressure requirements. The applications include also revival of the liquid loaded wells.

In recent years the industry has become more aware of their applications and benefits. This paper covers their applications, including; boosting production from selected oil and gas wells, boosting the pressure of low pressure gas, prevent flaring very low pressure gas, eliminate the need for intermediate compressors, de-bottlenecking compressors, prevent HP wells backing out LP wells, and revival of liquid loaded wells. In addition to referring to recent field examples, issues such as performance, ranges of operation, key features of the system and solutions for gas or oil production applications are described. Key operation issues are also addressed.

The paper addresses the economic aspects shown by typical pay-back periods for recovery of the capital from the benefits gained such as added revenue.
Quantifying the Role of Hematite Cement in Controlling Permeability in a Deep Tight Gas Reservoir from the North Sea
Authors: Ali Arfan , Abdalh Salem , Potter David K.
Published: January 2012

Recent work has shown the potential usefulness of magnetic susceptibility and hysteresis techniques in assessing the impact of fine grained hematite on permeability in red and white sandstone samples (Potter et al. 2009; Ali and Potter, 2011b). The present study demonstrates that hematite cementation is a major controlling factor on permeability in a deep tight gas reservoir in the North Sea. Magnetic susceptibility measurements undertaken on core plugs in this reservoir showed a strong correlation with probe permeability performed on the same plug samples. Moreover, samples with a higher content of hematite exhibited lower permeability values. Thin section analysis revealed the presence of a thin (approximately 10-15µm) rim of hematite cement surrounding quartz grains, which block pore connections and reduce permeability.

Magnetic hysteresis measurements on some representative samples indicated a very similar paramagnetic clay content in both the low and high permeability samples suggesting that the clay (mainly illite) is not the dominant controlling factor producing the variations in permeability that we observed. Since samples with higher hematite content exhibit lower permeability it appears that hematite is a major control on the permeability variations seen in this reservoir. Whilst the paramagnetic clays undoubtedly have an influence on the absolute permeability value, since increasing paramagnetic clay content has previously been shown to correlated with decreasing permeability (Potter, 2007), small amounts of hematite cement can significantly further reduce the permeability. Analysis of the magnetic hysteresis parameters on a Day plot indicated that the permeability was essentially independent of the hematite particle size for the fine particle sizes observed in this study.
An Effective Approach to Unconventional Resource Exploration in the Middle East
Authors: Bouhlel Aziza Moumen , Bryant Ian
Published: January 2012

In the last decade, shale resource exploitation has transformed North American production capacity through technological improvements in horizontal drilling and the ability to efficiently stimulate horizontal wellbores using multiple hydraulic fractures. The 2011 U.S. Energy Information Administration estimates there are unproved, technically recoverable shale gas resources of 827 Tcf (in addition to 20.1 Tcf of reserves) in the USA alone. Exploration and exploitation of Middle East organic-rich shales are just beginning, and discovery of economically viable resources requires a concerted effort. While Middle East resources in place could be much greater than those in North America, "sweet spots" need to be found in which established source rocks can also function as reservoirs. Evaluating these opportunities requires refined reservoir characterization workflows rather than the statistical approach that characterized early development of North American shale plays, which benefited from high gas prices, numerous existing wells, and infrastructure to support drilling and fracturing. With lower well density and higher well costs than in North America, successful exploration for unconventional hydrocarbon resources in the Middle East will necessarily rely more on modeling.

A petroleum systems–oriented approach defines sweet spots by predicting reservoir quality and potential completion quality. Using proven and effective tools, sweet spots are identified early in the life of unconventional plays. Since reliable, comprehensive data concerning the behavior of shale resource systems under varying conditions are not widely available in the Middle East, petroleum systems modeling would yield key risk and value information.

Standard petroleum systems modeling tools have recently been improved, providing more accurate results based on experience of modeling unconventional plays. By extending traditional basin and petroleum systems modeling with sophisticated adsorption functionality, the modeling of hydrocarbon adsorption on kerogen and primary migration within tight source rocks has been significantly enhanced. These methods have the potential to improve the efficiency and effectiveness of Middle East shale resource evaluation.
Design, Application, and Implementation of Well Intervention Services within a Deep HP/HT Tight Gas Exploration and Appraisal Project
Authors: Curtino Joe , Ouaguennouni Mourad , Judd Tobias , Al Habsi Ali
Published: January 2012

The appraisal of deep tight gas reservoirs can be technically and economically challenging, with success dependent on applying the most efficient completion technology. Inevitably, this includes designing well completions that encompass the deployment of multiple hydraulic fracturing treatments. There is a tendency in the completion design phase to under-assess the number and variety of interventions that a well could undergo during its evaluation. Subsequently, the development and application of the appropriate well intervention strategy is crucial in maximizing the well potential and reservoir understanding. The deliverable of any tight gas appraisal program is to increase the level of confidence in continuing to pursue the resource opportunity by demonstrating stable and sustainable gas inflow flow rates.

Recent drilling success targeting deep frontier gas reservoirs, such as the Amin located in the central part of Oman, have resulted in the need to evolve the well intervention process to include several new (for the region) technologies. These included the deployment of abrasive perforating to facilitate the initial formation breakdown operations, milling out the shoe track for a hydraulic fracturing treatment in an openhole setting, restoring full wellbore access by milling out multiple frac plugs, and temporary installation of a velocity string to eliminate liquid loading issues. Historically, many of these individual processes have been attempted or deployed with varying levels of success, but this is the first time that they have been integrated into a well strategy.

This paper summarizes the process of selecting the best options for well intervention operations in low-permeability gas reservoirs. The integrated work design consideration and results of these completion techniques will be presented along with the key learnings derived from the process.
Potential Unconventional Gas Supplies in Bangladesh
Authors: Bishop Michele , Cronshaw Mark , Lencioni Letha , Rensberger Shannon
Published: January 2012

There is the possibility of discovering and developing coal bed methane (CBM) and shale gas in Bangladesh; however the amounts of gas and the timing of exploration and development are uncertain. It is common to use probabilistic methods to determine the range of possible unconventional resources as well as the associated probabilities and reserve/resource categorization. Such probabilistic methods can be extended to consider the exploration and development timing as well as the amount of resources. We have prepared such a country-wide model for Bangladesh that considers gas supply from existing fields, known prospects and leads, unmapped resources, CBM, and shale gas.

The model results demonstrate possible outcomes for three time horizons: short term (next 5 years), intermediate term (5-10 years), and long term (beyond 10 years). The short term gas supply is dominated by supplies from existing fields. Gas availability in the intermediate and long terms is strongly influenced by possible new discoveries including unconventional gas. The model predicts the probability of sufficient gas supplies to meet demand, and also the possibility of gas supplies in excess of demand. The results are useful for planning concerning (a) gas imports and/or use of other energy types, and (b) the potential need for gas exports or the curtailment of gas production in the event of very substantial gas discoveries. The model also demonstrates the potential benefit associated with acceleration of exploration and development activities.

The probabilistic framework naturally results in a range of scenarios. Such a framework with multiple scenarios and associated probabilities allows for a more informed debate about country-wide energy planning.
Wattenberg Field Unconventional Reservoir Case Study
Authors: Moritz Edwin C. , Barron Natalie
Published: January 2012

The Wattenberg Field located in the Denver Basin of Colorado USA has been explored and developed since the 1970s. The field contains large reserves of primarily gas and some condensate in unconventional tight sand and shale reservoirs. Over time, technologies have emerged to efficiently exploit the hydrocarbon resources in this field and this includes hydraulic fracture techniques, down spacing and identification of sweet spots. This presentation summarizes the development of the techniques used to exploit these unconventional reservoirs and such techniques can be used for future exploration and development of other unconventional reservoirs globally.
Wireline Formation Tester Complemented by Integrated Petrophysical Evaluation Characterizes an Unconventional Reservoir: A Case Study from Western Onshore India
Authors: Rai Kamaleshwar , Anjaneyulu J. V. , Tellapaneni Prasanna K. , Shukla Sourabh , Devkar Sambhaji
Published: January 2012

The focus on unconventional opportunities is growing in several basins worldwide. As unconventional opportunities grow and develop, a reliable evaluation of unconventional resources and reserves poses a challenge to our industry. The novelty of many unconventional plays implies limited historical trends. Also, because no two unconventional plays are the same and variations within a play can yield significantly different results, the evaluation of such reservoirs is a challenge.

In the case study presented, a workflow is described in which trap wash overlying a fractured basement was successfully evaluated for the first time using the wireline-conveyed dual packer interval pressure transient testing (IPTT) technique. An integrated petrophysical evaluation including nuclear magnetic resonance (NMR) was used for hydrocarbon saturation and permeability determination in conjunction with classical openhole logs and other advanced logs. Borehole microimager-derived results were useful in detailed fracture characterization and optimization of the dual packer position for a successful IPTT operation that proved oil from the section above fractured basement.
A Workflow for Modeling and Simulation of Hydraulic Fractures in Unconventional Gas Reservoirs
Authors: Mirzaei M.. , Cipolla C. L.
Published: January 2012

Economic production from an unconventional gas reservoir is possible only if a complex fracture network can be created that connects a huge reservoir area to the wellbore effectively. This fracture network can be created by hydraulic fracturing. Several techniques can be used to present hydraulic fractures in a simulation model. In a simple model it is assumed that the fractures lie in the single plane of local tartan grid cells that best approximates the true geometric orientation of the fracture. The local refinement is symmetrically placed within the plane of host cells and has small cells close to the fracture that logarithmically increase in size away from the fracture. Explicitly calculated transmissibility multipliers on the faces of the cells that intersect the fracture are used to model the flow between matrix and the hydraulic fracture. The spacing and conductivity of the hydraulic fractures are critical parameters that control well performance.

A new reservoir modeling and simulation technique has been developed for these complex fracture networks that combines discrete fracture network (DFN) modeling and unstructured fracture (UF) modelingto simulate well performance and improve stimulation design. This is very important for modeling and simulation of a well with hydraulic fractures in a shale gas reservoir with natural fractures.

Results from this new model show a gas shale reservoir can be drained more effectively if a complex fracture network can be created by hydraulic fracture stimulation. In addition to a large increase in the production, the number of fracture treatment stages can be reduced if a high-conductivity fracture can be created, adding to the economic viability of the development of unconventional gas sources. The modeling and simulation technique presented in this paper can help identify stimulation and completion strategies that will significantly improve well performance and ultimate recovery from an unconventional gas reservoir.
Constraining Stress Tensors Using Shear Sonic Anisotropy Directions and Breakout Orientations in a Deviated Well, Western Offshore, India
Authors: Kumar Rajeev , Rao Dhiresh Govind , Swain Saraswat
Published: January 2012

Knowledge of the magitude and direction of the three principal in-situ stresses is critical for performing wellbore stability analysis in order to optimize the mud weight program for drilling. In vertical wells, breakouts tend to occur parallel to the minimum horizontal stress direction, and the sonic fast shear azimuth (FSA) coincides with the direction of maximum horizontal stress. However, for arbitrary well deviations, breakouts and the FSA are not oriented 90 degrees to each other. Breakout orientations in a deviated well depend on well trajectory as well as in-situ stress magnitudes and orientations, which can vary from the scale of the regional to the well scale. We present a case study from western offshore, India, where breakouts associated with different well orientations were used to determine the in-situ stress regime and minimum horizontal stress direction. In addition, the stress-induced sonic fast shear azimuth at different well orientations was determined and analyzed using dispersion plots. The horizontal stress anisotropy was confirmed with crossover behavior on the fast shear - slow shear profile. Because the sonic fast shear azimuth and the breakout direction are complementary, careful evaluation of change in their orientation with well deviation improved inferred stress directions. The study concludes that a strike-slip stress regime (σH > σv > σh) exists, which is different from the previously determined stress regime. We further demonstrate that once stress state and stress directions are determined, wellbore stability analysis using a mechanical earth model (MEM) can be performed more accurately. In this study, a post-drill MEM that comprises rock mechanical properties, stress tensors, and pore pressure was used to investigate the causes of overgauged holes and drilling problems that occurred in the deviated wells in this region.
Intervention-Less Completions for Unconventional Shale Plays
Authors: Mason Jane , Tough John , Day Paul , Hatton Shirley
Published: January 2012

There is a very significant move today towards multiple zone fracturing operations in a single well where zones are separated and individually fractured, particularly in shale gas completions. This technique has to date involved the use of ball seat activated sliding sleeves located across each zone, with consequent reductions in internal diameter (ID) and attendant flow characteristic limitations or selective perforating, fracing and isolation with a bridge plug in a cemented casing string while working up the hole. Both approaches involve many downhole intervention operations such as perforating, shifting sleeves, running plugs and subsequently milling them up with coiled tubing (CT) intervention, all of which extend the length of the operation and add to the overall costs.

To simplify the process of multiple fracturing operations, especially in open hole, a new approach has been designed which uses Radio Frequency Identification (RFID) techniques to remotely operate sliding sleeves. The number of sleeves that can be run in a well using this technology is essentially unlimited, each one having the same ID and a unique electronic address which allows it to be operated remotely at will. This approach provides for a means of making considerably more zones available for treatment without physical intervention with CT or wireline and thereby speeds the multiple frac operations and allows for wellbore clean up from the toe to the heel of the well.

In this paper the authors will describe the design and operation of the RFID operated frac sleeves and the advantages they provide. They will go on to detail the Worlds’ first remotely operated horizontal openhole frac completion where frac sleeves and swell packers were used in an extended reach horizontal shale gas well.
The Absolute Arithmetic Continuum and the Unification Of all Numbers Great and Small
Authors: Ehrlich Philip
Published: January 2012

In his monographOn Numbers and Games, J. H. Conway introduced a real-closed field containing the reals and the ordinals as well as a great many less familiar numbers including −ω, ω/2, 1/ω,and ω − π to name only a few. Indeed, this particular real-closed field, which Conway callsNo, is so remarkably inclusive that, subject to the proviso that numbers—construed here as members of ordered fields—be individually definable in terms of sets of NBG (von Neumann–Bernays–Gödel set theory with global choice), it may be said to contain “All Numbers Great and Small.” In this respect,Nobears much the same relation to ordered fields that the system ℝ of real numbers bears to Archimedean ordered fields.

In Part I of the present paper, we suggest that whereas ℝ should merely be regarded as constituting an arithmetic continuum (modulo the Archimedean axiom),Nomay be regarded as a sort of absolute arithmetic continuum (modulo NBG), and in Part II we draw attention to the unifying frameworkNoprovides not only for the reals and the ordinals but also for an array of non-Archimedean ordered number systems that have arisen in connection with the theories of non-Archimedean ordered algebraic and geometric systems, the theory of the rate of growth of real functions and nonstandard analysis.

In addition to its inclusive structure as an ordered field, the systemNoof surreal numbers has a rich algebraico-tree-theoretic structure—a simplicity hierarchical structure—that emerges from the recursive clauses in terms of which it is defined. In the development ofNooutlined in the present paper, in which the surreals emerge vis-à-vis a generalization of the von Neumann ordinal construction, the simplicity hierarchical features ofNoare brought to the fore and play central roles in the aforementioned unification of systems of numbers great and small and in some of the more revealing characterizations ofNoas an absolute continuum.
In Praise of Replacement
Authors: Kanamori Akihiro
Published: January 2012

This article serves to present a large mathematical perspective and historical basis for the Axiom of Replacement as well as to affirm its importance as a central axiom of modern set theory.
Second Order Logic or Set Theory?
Authors: Väänänen Jouko
Published: January 2012

We try to answer the question which is the “right” foundation of mathematics, second order logic or set theory. Since the former is usually thought of as a formal language and the latter as a first order theory, we have to rephrase the question. We formulate what we call the second order view and a competing set theory view, and then discuss the merits of both views. On the surface these two views seem to be in manifest conflict with each other. However, our conclusion is that it is very difficult to see any real difference between the two. We analyze a phenomenonwe call internal categoricity which extends the familiar categoricity results of second order logic to Henkin models and show that set theory enjoys the same kind of internal categoricity. Thus the existence of non-standard models, which is usually taken as a property of first order set theory, and categoricity, which is usually taken as a property of second order axiomatizations, can coherently coexist when put into their proper context. We also take a fresh look at complete second order axiomatizations and give a hierarchy result for second order characterizable structures. Finally we consider the problem of existence in mathematics from both points of view and find that second order logic depends on what we call large domain assumptions, which come quite close to the meaning of the axioms of set theory.
Medical Treatment of Alcohol Dependence: A Systematic Review
Authors: Miller Peter M. , Book Sarah W. , Stewart Scott H.
Published: January 2012

Objective:

To summarize published data on pharmacologic treatments for alcohol dependence alone and in combination with brief psychosocial therapies that may be feasible for primary care and specialty medical settings.

Methods:

We conducted electronic searches of published original research articles and reviews in MEDLINE, SCOPUS, CINAHL, Embase, and PsychINFO. In addition, hand searches of reference lists of review articles, supplemental searches of internet references and contacts with experts in the field were conducted. Randomized controlled studies published between January 1960 and August 2010 that met our inclusion/exclusion criteria were included.

Results:

A total of 85 studies, representing 18,937 subjects, met our criteria for inclusion. The evidence base for oral naltrexone (6% more days abstinent than placebo in the largest study) and topiramate (prescribed off-label) (e.g., 26.2% more days abstinent than placebo in a recent study) is positive but modest. Acamprosate shows modest efficacy with recently abstinent patients, with European studies showing better results than U.S. ones. The evidence-base for disulfiram is equivocal. Depot naltrexone shows efficacy (25% greater reduction in rate of heavy drinking vs. placebo, in one of the largest studies) in a limited number of studies. Some studies suggest that patients do better with extensive psychosocial treatments added to medications while others show that brief support can be equally effective.

Conclusions:

Although treatment effects are modest, medications for alcohol dependence, in conjunction with either brief support or more extensive psychosocial therapy, can be effective in primary and specialty care medical settings.
When Non-Epileptic Seizures Fool the Experts
Authors: Nguyen Mathew L. , Shapiro Michael A. , Demetree Julie M. , White Kimberly A.
Published: January 2012

Even when non-epileptic seizures are correctly diagnosed, appropriate treatment recommendations may not be fully or correctly implemented. We present a case of a 17-year-old girl with frequent non-epileptic seizures who presented for frequent trips to the emergency room (ER) and was admitted to an inpatient Child and Adolescent Psychiatric Facility. Despite being informed that episodes were non-epileptic seizures, various staff and healthcare providers at the psychiatric hospital continued to send the patient to the ER to treat suspected epileptic seizures. We discuss possible reasons why this may have occurred, including psychosocial and emotional reactions of staff members to the episodes. This discussion may also help to explain the persistence of the patient's episodes. We also present options for minimizing the potential for future mismanagement of non-epileptic seizures.
Alternative Medicine Techniques Have Non-Linear Effects on Radiation Response and Can Alter the Expression of Radiation Induced Bystander Effects
Authors: Mothersill Carmel , Smith Richard , Henry Matthew , Seymour Colin , Wong Raimond
Published: January 2012

Many so-called “alternative medicine” techniques such as Reiki and acupuncture produce very good outcomes for intractable pain and other chronic illnesses but the efficacy is often dismissed as being psychosomatic. However a plausible mechanism does exist i.e. that the treatments alter the electromagnetic fields in living organisms and thereby prevent or reduce activity of neurons which lead to the pain. Low doses of ionising radiation have similar effects on electromagnetic fields and are known to induce signaling cascades in tissues due to ion gradients. To test this hypothesis cell cultures were exposed to Reiki - like and to acupuncture - like treatments, both performed by qualified practitioners. The cells were exposed either before or after the treatment to x-rays and were monitored for production of direct damage or bystander signals. The data suggest that the alternative techniques altered the response of cells to direct irradiation and altered bystander signal mechanisms. We conclude that alternative medicine techniques involving electromagnetic perturbations may modify the response of cells to ionizing radiation. In addition to the obvious implications for mechanistic studies of low dose effects, this could provide a novel target to exploit in radiation protection and in optimizing therapeutic gain during radiotherapy.
Alexander Brunschwig: 110 years from birth September 11, 1901 - August 7, 1969
Authors: Kecmanovic Dragutin , Pavlov Maja , Ceranic Miljan , Kostic Dragan , Mihajlovic Branislav
Published: January 2012

Alexander Brunschwig was very important person in surgical oncology during
the 20th century. He helped Maximow and Bloom to write their well-known
histology text "A Text-Book of Histology", he was the first to do a one-stage
radical pancreatoduodenectomy and pelvic exenteration. Doctor Alexander
Brunschwig was born in El Paso, Texas, on September 11, 1901. He graduated
from Rush Medical College in 1927. He was named for the chief of gynecology
and clinical assistant at Clinics and Medical School of the Chicago
University in 1933. He became professor of surgery at the same University in
1940 where he worked until 1947. Doctor Brunschwig moved to New York in 1947
and became the Chief of gynecology in Memorial Hospital for Cancer and Allied
Diseases and professor of clinical surgery at Cornell University at Medical
College. He published some very important books about oncology, "The Surgery
of Pancreatic Tumors", "Radical Surgery in Advanced Abdominal Cancer" and "L?
Exenteration pelvienne".
Current options in local anesthesia for groin hernia repairs
Authors: Kulacoglu Hakan , Alptekin Alp
Published: January 2012

Inguinal hernia repair is one of the most common procedures in general
surgery. All anesthetic methods can be used in inguinal hernia repairs. Local
anesthesia for groin hernia repair had been introduced at the very beginning
of the last century, and gained popularity following the success reports from
the Shouldice Hospital, and the Lichtenstein Hernia Institute. Today, local
anesthesia is routinely used in specialized hernia clinics, whereas its use
is still not a common practice in general hospitals, in spite of its proven
advantages and recommendations by current hernia repair guidelines. In this
review, the technical options for local anaesthesia in groin hernia repairs,
commonly used local anaesthetics and their doses, potential complications
related to the technique are evaluated. A comparison of local, general and
regional anesthesia methods is also presented. Local anaesthesia technique
has a short learning curve requiring simple training. It is easy to learn and
apply, and its use is in open anterior repairs a nice way for health care
economics. Local anesthesia has been shown to have certain advantages over
general and regional anesthesia in inguinal hernia repairs. It is more
economic and requires a shorter time in the operating room and shorter stay
in the institution. It causes less postoperative pain, requires less
analgesic consumption; avoids nausea, vomiting, and urinary retention.
Patients can mobilize and take oral liquids and solid foods much earlier.
Most importantly, local anesthesia is the most suitable type of anesthesia in
elder, fragile patients and patients with ASA II-IV scores.
Is routine cystoscopy justified in female stress urinary incontinence?
Authors: Topuzovic Cedomir , Pejcic Tomislav , Basic Dragoslav , Djurasic Ljubomir , Hadzi-Djokic Jovan
Published: January 2012

The investigation of women with SUI the Serbian urologist traditionally
begins with cystoscopy to reduced risk of bladder tumor. There is no doubt
regarding its ability to detect bladder cancer presented with characteristic
symptoms or pathologic results of urinalyses. We discuss its routine use in
patients presenting with symptomatology of SUI. The retrospective study was
performed in order to evaluate clinical justifiability and cost/benefit ratio
of routine cystoscopy in women with stress urinary incontinence (SUI) whose
were surgically treated. We reviewed records of 95 female, mean age 56,5
years (rang 46-78) who underwent SUI surgery at eightyear period. The
clinical variables, including urinary symptoms, results of urinalyses,
ultrasound records and cystoscopic findings, were obtained from the hospital
reports. Insignificantly abnormal cystoscopic findings were reported in 31%
patients (vagina - like epithel, trigonitis, uterus wall impression,
hyperemia, polypoid proliferation and mild trabeculation). No cases of
malignancy were incidentally discovered. In female SUI cystoscopic finding
was insignificantly abnormal and was not influenced further therapy and
contraindicated the planned SUI surgery. Routine cystoscopy in women with SUI
cannot be justified only by customary practice or tradition of older
generation urologists.
Quality of life and functional capacity one year after coronary artery bypass graft surgery
Authors: Nedeljkovic Una , Krstic Nevena , Varagic-Markovic Slavica , Putnik Svetozar
Published: January 2012

Objectives: To analyze functional capacity and quality of life of patients
one year after coronary artery bypass graft surgery (CABG) and identify
factors that influence them in order to accomplish maximal recovery. Methods:
Observational study included 89 patients undergoing elective CABG, who were
tested preoperatively and one year after operation using Short form 12 item
health survey (SF-12), Duke Activity Status Index (DASI) questionnaire and
questionnaire regarding participation in rehabilitation program. Results:
After one year, DASI and quality of life-physical component summary score
(SF-12 PCS) significantly improved (p<0.001; p<0.05). No statistically
significant improvement in mental component summary has been registered. In
domains of physical component summary, only general health was significantly
better (p<0.05). There was moderate correlation of SF-12 PCS postoperatively
with SF-12 mental component summary (SF-12 MCS) preoperatively. DASI scores
preoperatively and postoperatively are found to be significantly higher in
men comparing to women (p<0.05). Multiple regression analysis found DASI
preoperatively (R2=0.62, ?=0.42, p<0.05) and age (?=-0.53, p<0.05) to be
significant predictors of DASI postoperatively in women. Enrollment in
rehabilitation program didn?t influence DASI and SF-12 scores one year after
CABG. Conclusions: Although functional capacity and physical component of
quality of life improved, factors that influence them still remain unclear.
It seems that mental health status and personality profile, as well as the
alternative modalities of rehabilitation, might play important role in long
lasting effects of improvement.
Kinesiological characteristics of ankle joint and rearfoot motion
Authors: Spasovski Dusko , Vukasinovic Zoran , Stevanovic Vladan , Slavkovic Nemanja
Published: January 2012

Kinesiological analysis of tarsal bones provides better understanding of foot
disorders, especially in early childhood, when radiography is hindered by
delayed ossification of foot bones. Children begin to walk in the age of 9-15
months, with rearfoot inversion only in initial contact phase, while
inversion during terminal stance phase is delayed. Adult walking pattern is
usually established at six years of age. Talocrural joint axis medial slope
shifts during movements depending on the what part of talus comes in contact
with maleolli. As a result, plantar flexion includes valgus, and dorsal
flexion includes varus inclination. Subtalar joint axis highly varies among
individuals: from 200-680 in sagittal and from 40-470 in frontal plane, with
impact on coupled lower leg rotation movements around longitudinal axis.
Midtarsal joint has two axes, and their position control the rigidity of
forefoot and midfoot kinetic chain. Movement planes of tarsal bones strongly
influence walking pattern as well as secure foot development.
Foot examination in the period of development
Authors: Slavkovic Nemanja , Vukasinovic Zoran , Bascarevic Zoran
Published: January 2012

Feet are maybe the key part of our musculoskeletal system that establishes
upright position and movement. Their role is multiple - they maintain the
balance of the body, push the body forward when walking and absorb mechanical
pressure created in contact with the surface. Therefore, correct anatomic and
functional development of foot is of vital importance. The most frequent
reasons for examination of foot in the period of development are pain,
deformity and incorrect walk. Our task is to detect the cause of the problem
with clinical examination in the shortest possible period of time or to
assess which additional diagnostic procedure would be the most suitable. A
clinical examination of foot in the period of development involves
inspection, palpation, percussion, auscultation, examination of joint
mobility, examination of sensory-motor function and conducting specific
tests. In some cases detailed and properly conducted clinical examination can
prove to be sufficient to establish a complete and accurate diagnosis.
Patients of this specific age may be insufficiently cooperative, mistrustful,
shy or even afraid. Our approach and manipulations during the clinical
examination need to be adapted completely to such patients and their
characteristics.
Flatfoot in children
Authors: Vukasinovic Zoran , Spasovski Dusko , Matanovic Dragana , Zivkovic Zorica , Stevanovic Vladan , Janicic Radmila
Published: January 2012

Foot arches are defined by the position of bones and stabilized by active and
passive soft tissue structures. The most significant foot arches are
longitudinal, medial and lateral. During lifetime they develop and change,
while the most significant disorder represents the flatfoot. During the first
two years of life, the flatfoot in full weight bearing position is considered
a normal physiological condition, while in later age it represents a
deformity requiring additional diagnostics and treatment. The flexible
flatfoot is caused by ligamentous laxity, it is mostly pain-free and is
treated symptomatically (prescription of adequate shoes and kinesitherapy).
The rigid foot is most often caused by bone changes (tarsal coalition,
vertical congenital talus) occurring idiopathically or within neuromuscular
pathological conditions, with mostly present pain problems. In such cases
treatment is also initiated by non-surgical methods, however, some type of
surgical treatment is most frequently necessary to be used.