bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New TH-CDMA Scheme for Dispersive Infrared Channel and Its Performance Evaluation
Authors: Hamdi Mazda , Nasiri-Kenari Masoumeh 
Published: April 2011

Abstract
Infrared indoor wireless communications using nondirected links are subject to severe multipath distortion which causes intersymbol interference (ISI). To lessen multipath distortion effect and thereby to improve the system performance, in this paper, we consider a new time-hopping based multiple access scheme for this channel, in which one pulse is transmitted in each bit interval. The position of the pulse is determined based on the output of a low rate error correcting code along with the user's dedicated PN code. We evaluate the multiple access performance of the system for correlation receiver considering background noise, dark current, and thermal noise. We compare the performance of our proposed multiple access scheme with those of the previously introduced code division multiple access schemes for infrared communications, like CDMA and Frame Time Hopping (FTH). Our results show that, for the same bandwidth and bit rate, the proposed system substantially excels the other methods in term of bit error rate, or equivalently the number of the users supported at a fixed bit error rate.
Cleft Lip and Palate in the Arts: A Critical Reflection
Authors: Saman Masoud , Gross Justin , Ovchinsky Alexander , Wood-Smith Donald 
Published: April 2011

Background The aesthetics of facial structure are used by humans to measure one's beauty, character, and overall “goodness.” Individuals born with cleft lip and/or palate are often stigmatized and face much psychosocial adversity. Social attitudes and beliefs have a direct impact upon the psychological development of these individuals. Such social norms are in large part shaped by the physical representations of “good” and “attractive” in various art media including films, advertisements, and paintings. Objective Individuals born with a cleft have been portrayed in the artworks of different eras. The light in which they are portrayed stems from the prevalent beliefs of each period and sheds light on the social attitudes of each epoch toward clefts. Here we discuss the social and psychological ramifications of these works. We then review several artworks representing cleft lip and/or palate and propose an active role for the artist in shaping social attitudes regarding facial deformities. Methods Numerous articles and works of arts were examined and inspected for signs of facial deformity, with particular attention to cleft lip and/or palate. Conclusion Social media have an important role in defining the norms of society. Much of the art of the past has depicted negatively individuals born with cleft lip and/or palate deformity, thus excluding them from the norm. In order to decrease the negative social stigmas of cleft lip and/or palate, it is now the responsibility of society to widen its range of norms to include individuals born with these deformities through “normal” representations in the various media.
Influence of a Machined Collar on Crestal Bone Changes Around Titanium Implants: A Histometric Study in the Canine Mandible
Authors: Hermann Joachim S. , Jones Archie A. , Bakaeen Lara G. , Buser Daniel , Schoolfield John D. , Cochran David L. 
Published: April 2011

Background: It has been shown that peri‐implant crestal bone reactions are influenced by both a rough–smooth implant border in one‐piece, non‐submerged, as well as an interface (microgap [MG] between implant/abutment) in two‐piece butt‐joint, submerged and non‐submerged implants being placed at different levels in relation to the crest of the bone. According to standard surgical procedures, the rough–smooth implant border for implants with a smooth collar should be aligned with the crest of the bone exhibiting a smooth collar adjacent to peri‐implant soft tissues. No data, however, are available for implants exhibiting a sandblasted, large‐grit and acid‐etched (SLA) surface all the way to the top of a non‐submerged implant. Thus, the purpose of this study is to histometrically examine crestal bone changes around machined versus SLA‐surfaced implant collars in a side‐by‐side comparison.Methods: A total of 60 titanium implants (30 machined collars and 30 SLA collars) were randomly placed in edentulous mandibular areas of five foxhounds forming six different subgroups (implant subgroups A to F). The implants in subgroups A to C had a machined collar (control), whereas the implants in subgroups D to F were SLA‐treated all the way to the top (MG level; test). Furthermore, the MGs of the implants were placed at different levels in relation to the crest of the bone: the implants in subgroups A and E were 2 mm above the crest, in subgroups C and D 1 mm above, in subgroup B 3 mm above, and in subgroup F at the bone crest level. For all implants, abutment healing screws were connected the day of surgery. These caps were loosened and immediately retightened monthly. At 6 months, animals were sacrificed and non‐decalcified histology was analyzed by evaluating peri‐implant crestal bone levels.Results: For implants in subgroup A, the estimated mean crestal bone loss (± SD) was −0.52 ± 0.40 mm; in subgroup B, +0.16 ± 0.40 mm (bone gain); in subgroup C, −1.28 ± 0.21 mm; in subgroup D, −0.43 ± 0.43 mm; in subgroup E, −0.03 ± 0.48 mm; and in subgroup F, −1.11 ± 0.27 mm. Mean bone loss for subgroup A was significantly greater than for subgroup E (P = 0.034) and bone loss for subgroup C was significantly greater than for subgroup D (P <0.001).Conclusions: Choosing a completely SLA‐surfaced non‐submerged implant can reduce the amount of peri‐implant crestal bone loss and reduce the distance from the MG to the first bone–implant contact around unloaded implants compared to implants with a machined collar. Furthermore, a slightly exposed SLA surface during implant placement does not seem to compromise the overall hard and soft tissue integration and, in some cases, results in coronal bone formation in this canine model.
Comparison of Fractured-Horizontal-Well Performance in Tight Sand and Shale Reservoirs
Authors: Ozkan E. , Brown M , Raghavan R. , Kazemi H. 
Published: April 2011

Summary
This paper presents a discussion of fractured-horizontal-well performance in millidarcy permeability (conventional) and micro- to nanodarcy permeability (unconventional) reservoirs. It provides interpretations of the reasons to fracture horizontal wells in both types of formations. The objective of the paper is to highlight the special productivity features of unconventional shale reservoirs. By using a trilinear-flow model, it is shown that the drainage volume of a multiple-fractured horizontal well in a shale reservoir is limited to the inner reservoir between the fractures. Unlike conventional reservoirs, high reservoir permeability and high hydraulic-fracture conductivity may not warrant favorable productivity in shale reservoirs. An efficient way to improve the productivity of ultratight shale formations is to increase the density of natural fractures. High natural-fracture conductivities may not necessarily contribute to productivity either. Decreasing hydraulic-fracture spacing increases the productivity of the well, but the incremental production gain for each additional hydraulic fracture decreases. The trilinear-flow model presented in this work and the information derived from it should help the design and performance prediction of multiple-fractured horizontal wells in shale reservoirs.
Generating 3D Permeability Map of Fracture Networks Using Well, Outcrop, and Pressure-Transient Data
Authors: Jafari A.. , Babadagli T.. 
Published: April 2011

SummaryWell-log and core information, seismic surveys, outcrop studies, and pressure-transient tests are usually insufficient to generate representative 3D fracture-network maps individually. Any combination of these sources of data could potentially be used for accurate preparation of static models.Our previous attempts showed that there exists a strong correlation between the statistical and fractal parameters of 2D fracture networks and their permeability (Jafari and Babadagli 2009). We extend this work to fracture-network permeability estimation using the statistical and fractal properties data conditioned to well-test information. For this purpose, 3D fracture models of 19 natural-fracture patterns with all known fracture-network parameters were generated initially. It is assumed that 2D fracture traces on the top of these models and 1D data from imaginary wells that penetrated the whole thickness of the cubic models were available, as well as pressure-transient tests of different kinds. The 1D and 2D data include statistical parameters and fractal characteristics of different features of the fracture system. Next, the permeability of each 3D fracture-network model was measured and then converted to a grid-based permeability map for drawdown well-test simulations using commercial software packages.Finally, an extensive multivariable-regression analysis (MRA) using the statistical and fractal properties and well-test permeability as independent variables was performed to obtain a correlation for equivalent fracture-network permeability. The equations were derived using different natural-fracture-network patterns. The cases requiring well (logs and cores) and reservoir (pressure-transient tests) data were identified. It was found that an equation honoring all types of data [i.e., outcrop (2D), wellbore data (1D), and welltest analysis (3D)] can accurately predict the actual permeability of the fracture system. For certain fracture-network types, reliable correlations can be obtained without 2D data, which are relatively difficult to obtain. These types of patterns were identified.
Proactive Maintenance in the Context of Integrated Operations Generation 2
Authors: af Sätra Ulf Skytte , Christensen Rebecca , Tanase Adrian , Koppervik Ingvar , Rokke Espen 
Published: April 2011

Summary
With increased requirements to improve production availability and to have a continuous updated overview of the condition status of subsea production systems (SPSs), oil and gas operators have increased focus to reach beyond the current practice of integrating onshore and offshore centers and processes for continuous onshore support. Integrated operations (IO) Generation 2 is a further extension to integrate operation centers of the operator and their vendors with heavily automated processes and digital services in a round-the-clock operation.
To reach IO Generation 2, proactive management as a foundation for operations with a pre-emptive maintenance program giving an early insight on coming abnormal issues is essential. Focusing on knowledge and understanding of how the equipment and installed base perform is essential and will be empowered by a management system that takes a holistic approach while an automatic integrity diagnoses functionality. To achieve IO Generation 2, work processes that promote collaboration and continuous improvements and visualization of the equipment will be necessary to facilitate a common awareness and maintain an optimum field operation.
By continuous monitoring of the integrity of the SPSs in an IO Generation 2 context, the condition and performance management (CPM) system enables pre-emptive maintenance leading to maximum production at minimum maintenance cost. Increasingly important, and supported by the CPM system, is the enforcing of health, safety, and environment (HSE) standards as stipulated in company goals and in national and international regulations.
The CPM system facilitates enhanced collaboration, and it is configured to support the identified IO Generation 2 work processes regarding work interfaces and roles. The agreed work processes for an IO Generation 2 setup make up the base foundation of the CPM system, from day-to-day monitoring and collaboration to in-depth analysis and improvement of the installed base performance.
Steamflood With Vertical Injectors and Horizontal Producers in Multiple Zones
Authors: Malik Sanjeev , Zhang Y.M.. M. , Asimi Mohammed Al , Gould Thomas L. 
Published: April 2011

Summary
The Mukhaizna heavy-oil field in the Sultanate of Oman desert has three distinct zones that require steam injection to enhance oil recovery. A new, geocellular-based reservoir description was prepared to evaluate the steamflood performance of these three zones using different horizontal- and vertical-well configurations. On the basis of the results of thermal simulations, the final design called for vertical wells injecting steam into all three zones, with three stacked horizontal production (HP) wells, one for each zone. One advantage of this design is the ability to control the steam flux from each vertical injector (VI) into each zone to mitigate early steam breakthrough and optimize recovery. After 2 years of steam injection, oil production is tracking the thermal model nicely.
Snorre Low-Salinity-Water Injection—Coreflooding Experiments and Single-Well Field Pilot
Authors: Skrettingland K.. , Holt T.. , Tweheyo M.T.. T. , Skjevrak I.. 
Published: April 2011

Summary
Low-salinity (lowsal) waterflooding has been evaluated for increased oil recovery (IOR) at the Snorre field. Coreflooding experiments and a single-well chemical tracer-test (SWCTT) field pilot have been performed to measure the remaining oil saturation after seawaterflooding and after lowsal flooding.
The laboratory coreflooding experiments conducted at reservoir and low-pressure conditions involved core material from the Upper and Lower Statfjord and Lunde formations. The core material from the Statfjord formations gave incremental recovery in the order of 2% of original oil in place (OOIP) by injection of diluted seawater. Similar amounts were produced during following NaCl-based lowsal injections. The same trend was observed in the high- and low-pressure experiments. No significant response to lowsal flooding was observed for Lunde cores. No response was normally observed during alkaline injection.
The SWCTT field pilot was carried out in the Upper Statfjord formation. The average oil saturations after seawater injection, after lowsal seawater injection, and after a new seawater injection were determined; no significant change in the remaining oil saturation was shown. The measured in-situ value of remaining oil saturation after seawaterflooding was in agreement with previous special core analysis (SCAL) experiments.
The measured effect of tertiary lowsal flooding from core experiments was in agreement with the SWCTT. Both measurements indicated only low or no effect from lowsal injection.
It has been suggested that lowsal flooding has a potential for improved oil recovery in all clayey sandstone formations containing crude oil. The results from this work indicate that the initial wetting condition is a crucial property for the effect of lowsal injection.
What Would Be the Impact of Temporarily Fracturing Production Wells During Squeeze Treatments?
Authors: Al-Rabaani Abdul , Mackay Eric J. 
Published: April 2011

Summary
It is generally assumed that scale-inhibitor squeeze treatments in production wells are displaced radially into the formation because it is normal to pump these treatments below the fracture pressure. However, it is known that thermal stresses as a result of injecting cold fluids can result in thermally induced fractures (TIFs). This paper addresses the evidence of thermal fracturing during low-volume (less than 10,000 bbl) treatments, and asks: What would be the impact on squeeze life of treating a well that was fractured during treatment vs. a nonfractured well?
The process involves modeling fractured and unfractured treatments to identify advantages and disadvantages of temporarily fracturing a well during a squeeze treatment in terms of inhibitor placement. While inhibitor may be placed at a greater distance from the wellbore if the formation is fractured during the treatment, the surface area of rock contacted during the treatment may be less than is the case in radial displacements. Issues such as consolidated vs. unconsolidated formations, initial reservoir temperature, fluid temperature at the sandface during injection, injection rate, and fracture dimensions should be considered.
In general, this work demonstrates that there are clear advantages to temporarily fracturing a well during a squeeze treatment, depending on the inhibitor-return concentrations required to prevent mineral-scale formation.
Unstained viable cell recognition in phase-contrast microscopy
Authors: Skoczylas M. , Rakowski W. , Cherubini R. , Gerardi S. 
Published: April 2011

AbstractIndividual cell recognition is a relevant task to be accomplished when single-ion microbeam irradiations are performed. At INFN-LNL facility cell visualization system is based on a phase-contrast optical microscope, without the use of any cell dye. Unstained cells are seeded in the special designed Petri dish, between two mylar foils, and at present the cell recognition is achieved manually by an expert operator. Nevertheless, this procedure is time consuming and sometimes it could be not practical if the amount of living cells to be irradiated is large. To reduce the time needed to recognize unstained cells on the Petri dish, it has been designed and implemented an automated, parallel algorithm. Overlapping ROIs sliding in steps over the captured grayscale image are firstly pre-classified and potential cell markers for the segmentation are obtained. Segmented objects are additionally classified to categorize cell bodies from other structures considered as sample dirt or background. As a result, cell coordinates are passed to the dedicated CELLView program that controls all the LNL single-ion microbeam irradiation protocol, including the positioning of individual cells in front of the ion beam. Unstained cell recognition system was successfully tested in experimental conditions with two different mylar surfaces. The recognition time and accuracy was acceptable, however, improvements in speed would be useful.
Développement durable et aide publique à la santé
Authors: I Barry Mamadou 
Published: April 2011

Dans le domaine de l’aide au développement, la période récente a été marquée par deux éléments : une mobilisation internationale forte autour du concept de développement durable et une accélération de l’aide publique à la santé au tournant des années 2000. Nous développons la thèse selon laquelle l’accélération de l’aide à la santé ne s'explique pas principalement par le consensus politique, institutionnel et scientifique autour du développement durable, mais plutôt par les logiques sécuritaires devenues dominantes.
Les nouvelles formes de l'aide publique au développement et l'éventuel "retour de l'État" dans les pays d'Afrique subsaharienne
Authors: Azoulay Gérard 
Published: April 2011

Les principes issus de la Conférence de Paris semblent remettre en cause l’un des fondements du consensus de Washington : le retrait de l’État. Ces nouveaux principes peuvent offrir aux pays moins avancés la possibilité de reconquérir la maîtrise de leurs politiques économiques. Cette réappropriation dépendra des modalités effectives de mise en œuvre de ces orientations par les pays. La contribution examine certaines des conditions nécessaires de réalisation de ces nouvelles orientations.
Les évolutions du modèle pétrolier russe : une réponse institutionnelle à la crise de l'industrie
Authors: Rossiaud Sylvain , Locatelli Catherine 
Published: April 2011

L’industrie pétrolière russe est depuis le début des années 1990 marquée par d’importants mouvements de réforme de son modèle organisationnel. La montée en puissance de l’État au sein de l’industrie est le facteur le plus souvent mentionné pour caractériser les évolutions en cours. L’article fournit un cadre d’interprétation à ces évolutions à partir d’une lecture néo-institutionnaliste des modèles d’organisation de l’industrie pétrolière. La réorganisation actuelle introduit une plus grande cohérence dans l’arrangement institutionnel encadrant la transaction d’ouverture de l’amont pétrolier à des opérateurs.
L'aide humanitaire dans les pays en développement : qui évalue qui ?
Authors: Pérouse de Montclos Marc-Antoine 
Published: April 2011

Les organisations humanitaires qui travaillent dans les pays en développement en crise sont généralement évaluées par leurs bailleurs de fonds, et non par les bénéficiaires de leurs programmes. Sollicitées et contrôlées par les parties prenantes au système, de telles évaluations présentent l’inconvénient de : 1) laisser de côté les institutions qui n’acceptent pas d’être examinées ; 2) biaiser l’analyse, en occultant plus ou moins délibérément les vrais problèmes ; 3) réduire l’exercice à une simple formalité technocratique, souvent vaine et vide de sens ; 4) pénaliser la capitalisation d’expériences en n’incitant pas à apprendre à partir des échecs.
Les déterminants de l'adoption de la téléphonie mobile au Burkina Faso
Authors: Zahonogo Pam 
Published: April 2011

Cet article analyse, sur la base de données collectées en 2007, l’adoption de la téléphonie mobile au Burkina Faso à l’aide d’un modèle Probit. Il révèle de profondes différences entre zone urbaine et rurale. Le niveau d’éducation, le revenu, le réseau social et l’âge de l’individu exercent une influence positive sur la probabilité d’adoption du téléphone mobile, alors qu’il n’existe pas de différence significative selon le genre. Les mesures de politique économique qui accroissent les revenus, le niveau d’éducation et améliorent la fourniture des services de base contribuent à un meilleur accès.