2,042 research outputs found
Quasinormal modes of Charged Regular Black Hole
The quasinormal modes (QNMs) of a regular black hole with charge are
calculated in the eikonal approximation. In the eikonal limit the QNMs of black
hole are determined by the parameters of the unstable circular null geodesics.
The behaviors of QNMs are compared with QNMs of Reisner-Nordstr\"{o}m black
hole, it is done by fixing some of the parameters that characterize the black
holes and varying another. We observed that the parameter that is related one
effective cosmological constant at small distances , determines the behaviors
of the QNMs of regular black hole with charge.Comment: arXiv admin note: text overlap with arXiv:1607.0247
Ranking efficient DMUs using cooperative game theory
The problem of ranking Decision Making Units (DMUs) in Data Envelopment Analysis (DEA) has been widely studied in the literature. Some of the proposed approaches use cooperative game theory as a tool to perform the ranking. In this paper, we use the Shapley value of two different cooperative games in which the players are the eļ¬cient DMUs and the characteristic function represents the increase in the discriminant power of DEA contributed by each eļ¬cient DMU. The idea is that if the eļ¬cient DMUs are not included in the modiļ¬ed reference sample then the eļ¬ciency score of some ineļ¬cient DMUs would be higher. The characteristic function represents, therefore, the change in the eļ¬ciency scores of the ineļ¬cient DMUs that occurs when a given coalition of eļ¬cient units is dropped from the sample. Alternatively, the characteristic function of the cooperative game can be deļ¬ned as the change in the eļ¬ciency scores of the ineļ¬cient DMUs that occurs when a given coalition of eļ¬cient DMUs are the only eļ¬cient DMUs that are included in the sample. Since the two cooperative games proposed are dual games, their corresponding Shapley value coincide and thus lead to the same ranking. The more an ef- ļ¬cient DMU impacts the shape of the eļ¬cient frontier, the higher the increase in the eļ¬ciency scores of the ineļ¬cient DMUs its removal brings about and, hence, the higher its contribution to the overall discriminant power of the method. The proposed approach is illustrated on a number of datasets from the literature and compared with existing methods
Presence of Euglossa (Euglossa) amazonica outside of the Amazon Basin ā biogeographic insights
Distributional patterns of euglossine bees are often shadowed by the most noticeablefeatures of the group, their morphology and behavior. With the constant discovery of records ofeuglossine species in novel localities, and the ongoing systematic work in the group, especiallyin Euglossa Latreille, a better picture of the evolution and biogeography of these bees is beingdeveloped. Provided here is an account of new records of Euglossa (Euglossa) amazonica Dressleroutside of the Amazon Basin region are presented along with a brief discussion of distributionalpatterns of the genus in northwestern South America
Cultural Clashes and Cultural Bridges: My Story in Afghanistan
Narrative inquiry and grounded theory are the methodology used to tell the story of the researcherās experiences in Afghanistan. This entailed identifying and researching a process of storytelling and weaving experiences together into a coherent and meaningful whole. The narrative inquiry method is appropriate for this project because the critical sources of data consist of the researcherās perceptions and experiences in Afghanistan, as reported in the form of narrative stories. This qualitative analysis focuses on examining and interpreting concrete pieces of evidence, formulating quantitative analysis along with sharing personal and professional experiences. To that end, external resources, including letters and data from numerous sources inform the overarching thesis of the dissertation. Topics examined include education, cultural differences, and levels of acceptance. The pieces of evidence supported by eight years of living in Afghanistan and working with diplomatic officials enriches the insights shared. Narrative inquiry, along with grounded theory, allow for greater understanding and analysis of these issues. Narrative inquiry addresses the qualitative components, while grounded theory addresses the data and evidence that is presented
Comparative Genital Morphology, Phylogeny, and Classification of the Orchid Bee Genus Euglossa Latreille (Hymenoptera: Apidae), with Distributional Modeling of Adventive Euglossines
Orchid bees (tribe Euglossini) are conspicuous members of the corbiculate bees owing to their metallic coloration, long labiomaxillary complex, and the fragrance-collecting behavior of the males, more prominently (but not restricted) from orchid flowers (hence the name of the group). They are the only corbiculate tribe that is exclusively Neotropical and without eusocial members. Of the five genera in the tribe, Euglossa Latreille is the most diverse with around 120 species. Taxonomic work on this genus has been linked historically to the noteworthy secondary sexual characters of the males, which combined with the other notable external features, served as a basis for the subgeneric classification commonly employed. The six subgenera Dasystilbe Dressler, Euglossa sensu stricto, Euglossella Moure, Glossura Cockerell, Glossurella Dressler and Glossuropoda Moure, although functional for the most part, showed some intergradations (especially the last three), and no phylogenetic evaluation of their validity has been produced. A general paucity in the use of male genitalic morphology has also been characteristic for the lineage. Here a comparative study of the male genitalic morphology for Euglossa is presented, and in turn, along with other external morphological features, used as a source of characters included in a phylogenetic analysis. A total of 41 Euglossa species representing the taxonomic diversity within the genus (all subgenera and species groups) plus five taxa as outgroups, and 79 characters are included in a comprehensive cladistic treatment. The resulting 64 shortest trees combined in a strict consensus tree recover as natural groups the subgenera Dasystilbe (monotypic), Euglossa s. str., and Euglossella (sister to all other Euglossa s. lat.). Glossura appears as paraphyletic in a derived clade that also includes Glossuropoda (sensu Moure) and some Glossurella; Glossura is proposed to be expanded to include all the species groups in this derived clade. Most Glossurella form a heterogeneous paraphyletic assemblage, and the subgenus is proposed to be narrowed to include the monophyletic group formed by E. bursigera Dressler and allies. A morphologically distinctive group in the Glossurella grade is also proposed as a new subgenus with E. oleolucens Dressler as type species, while the remaining species in the grade are classified as Euglossa incertae sedis. Recent molecular phylogenetic work largely agrees with the results here presented. The presence of two adventives orchid bee species in the USA is analyzed using occurrence data across their natural ranges to produce Species Distribution Models, so that the recently discovered naturalized populations of Euglossa viridissima Friese in southeastern Florida are projected not to expand beyond the Florida Peninsula, and the isolated records of Eulaema polychroma (MocsƔry) in the southwestern USA are most likely due to individual dispersion events or human introduction
Herpes Simplex Virus-Associated Aplastic Anemia
Aplastic anemia is an uncommon condition defined by peripheral pancytopenia in the context of hypocellular bone marrow. In the majority of cases, it is idiopathic in origin. However, exposure to certain drugs and toxins, autoimmune processes, and viral infections have been linked to this entity. This is the case of a 56-year-old female with an acute presentation of fever, odynophagia, and dysphagia. Physical examination revealed multiple hemorrhagic ulcers affecting her oropharyngeal mucosa with regions of necrosis. Mucosal biopsy was compatible with the presence of local necrosis and keratinization. Hematological analysis showed severe peripheral pancytopenia, and the bone marrow biopsy revealed a hypocellular marrow, findings consistent with aplastic anemia. An ample PCR viral panel revealed the presence of herpes simplex virus type 1 (HSV-1). The patient was placed on systemic antiviral therapy, followed by a rapid improvement of the mucositis as well as the peripheral and central pancytopenia. Our case indicated the possible association of HSV-1 infection and the development of aplastic anemia, an important and not yet recognized association considering the rapid improvement of the clinical picture once the underlying etiology was addressed
- ā¦