2007 ◽  
Vol 88 (10) ◽  
pp. 2679-2685 ◽  
Author(s):  
Maria Makuwa ◽  
Sandrine Souquière ◽  
Olivier Bourry ◽  
Pierre Rouquet ◽  
Paul Telfer ◽  
...  

In order to determine whether geographical or species clustering accounts for the distribution of hepatitis B virus (HBV) in subspecies of chimpanzees in Africa, four complete chimpanzee HBV (ChHBV) genome sequences were obtained from eight hepatitis B surface antigen-positive wild-born chimpanzees from Cameroon, Republic of Congo and Gabon. The serological profiles of these chimpanzees corresponded to the acute or chronic highly replicative phase of HBV infection, as confirmed by high plasma HBV loads. Analysis of the sequence alignment of 256 aa (S region) from the eight HBV-infected chimpanzees allowed us to determine the HBV amino acid patterns specific to each chimpanzee subspecies and to their geographical origin. Phylogenetic analysis of both the S region and the complete genome confirmed this distinctive clustering of eight novel ChHBV strains within Pan troglodytes. The strong phylogenetic associations of ChHBV sequences with both chimpanzee subspecies and their geographical origin were therefore confirmed.


2021 ◽  
Author(s):  
Yegor Se ◽  
◽  
Michael Sullivan ◽  
Vahid Tohidi ◽  
Michael Lazorek ◽  
...  

The well design with long lateral section and multistage frac completion has been proven effective for development of the unconventional reservoirs. Top-tier well production in unconventional reservoir can be achieved by optimizing hydraulic completion and stimulation design, which necessitates an understanding of flow behavior and hydrocarbon contribution allocation.  Historically, conventional production logging (PL) surveys were scarcely used in unconventional reservoirs due to limited and often expensive conveyance options, as well as complicated and non-unique inflow interpretations caused by intricate and changing multi-phase flow behavior (Prakash et al., 2008). The assessment of the cluster performance gradually shifted towards distributed acoustic (DAS) and temperature (DTS) sensing methods using fiber optics cable, which continuously gained popularity in the industry. Fiber optics measurements were anticipated to generate production profiles along the lateral with sub-cluster resolution to assist with optimal completions design selection. Encapsulation of the fiber in the carbon rod provided alternative conveyance method for retrievable DFO measurements, which gained popularity due to cost-efficiency and operational convenience (Gardner et al., 2015). Recent utilization of micro-sensor technology in PL tools, (Abbassi et al, 2018, Donovan et al, 2019) allowed dramatic reduction of the size and the weight of the PL toolstring without compromising wellbore coverage by sensor array. Such ultra-compact PL toolstring could utilize the carbon rod as a taxi and provide mutually beneficial and innovative surveillance combination to evaluate production profile in the unconventional reservoirs. Array holdup and velocity measurements across wellbore from PL would reveal more details regarding multi-phase flow behavior, which could be used for cross-validation and constraining of production inflow interpretation based on DFO measurements. This paper summarizes the lessons learned, key observations and best practices from the unique 4 well program, where such innovative combination was tested in gas rich Duvernay shale reservoir.


2016 ◽  
Vol 12 (5) ◽  
pp. 307.e1-307.e5 ◽  
Author(s):  
Nicolas Fernández ◽  
Armando Lorenzo ◽  
Darius Bägli ◽  
Ignacio Zarante

Author(s):  
Nunzia Carbonara

Agglomeration economies are positive externalities associated with the co-location of firms within a bounded geographic area. Traditionally, these agglomerative advantages have been expressed in terms of pecuniary externalities and they have been identified as one of the key sources of geographical cluster (GC) competitive advantage. However, in the last years the basics of competition are changed and the ability of firms to create new knowledge is more crucial for success rather than the efficiency in production. This has shifted the attention of scholars on the role of knowledge and learning in GCs. In line with these studies, this chapter suggests that agglomeration economies are related to both pecuniary externalities and knowledge-based externalities. The latter are benefits that co-located firms can gain in terms of development of knowledge. To investigate whether knowledge-based externalities affect geographical clustering of firms, an agent-based model is developed. By using this model, a simulation analysis is carried out.


Author(s):  
Saba Al-Rubaye ◽  
Anwer Al-Dulaimi ◽  
John Cosmas

Cognitive femtocell is a promising technology for the next generation wireless networks to improve the efficiency of spectrum utilization, coverage, and to attain higher data rates for indoor communications. In this chapter, the new Cognitive Femtocell Switching Unit (CFSU) is proposed to support handover management for 10-20 cognitive femtocells as a local geographical cluster. Thus, CFSU acts as a service coordinator between femtocells and macrocell areas to improve spectrum utilization and coexistence. Then, the chapter presents solutions for spectrum handover to achieve guaranteed quality of radio service, spectrum utilization, and enable an excellent local handover management to reduce unnecessary handovers between femtocell base stations. The challenges and solutions that are presented in this chapter have the ability to maintain services by evaluating the requested quality of services.


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