4,042 research outputs found
The evolution of hermaphroditism by an infectious male-derived cell lineage : an inclusive-fitness analysis
This work was supported by funding from Balliol College, the Royal Society (A.G.), and the University of Groningen (L.R.).There has been much recent interest in the role for genetic conflicts to drive the evolution of genetic systems. Here we consider the evolution of hermaphroditism in the scale insect tribe Iceryini and the suggestion that this has been driven by conflict between a female and an infectious male tissue derived from her father. We perform an inclusive-fitness analysis to show that, owing to genetic relatedness between father and daughter, there is scope for collaboration as well as conflict over the establishment of the infectious tissue. We also consider the evolutionary interests of a maternally inherited bacterial symbiont that has been implicated in mediating the tissue's establishment. More generally, our analysis reveals that genetic conflicts can drive the evolution of hermaphroditism.Publisher PDFPeer reviewe
Faculty Development In Member Institutions Of The Florida Faculty Development Consortium: Strategic Plans, Evaluation Models, Organization, and Funding
The purpose of this study was to examine strategic plans and evaluation models in light of organizational structures and funding to determine if member institutions in the Florida Faculty Development Consortium were investing in faculty development based on strategic and measurable criteria. Data were gathered through a mixed method survey mailed electronically to the individuals responsible for faculty development at 31 member institutions of the Florida Faculty Development Consortium. Even though the Consortium was comprised of public and private four-year institutions and public two-year institutions, faculty development programs in these institutions had similarities. Most programs had strategic plans, centralized faculty development units with dedicated staff, and institutional funding. In addition, most faculty development programs had evaluation models in which they collected reactionary responses, but little evidence existed that programs were measuring impact on faculty learning, faculty behavior change, or student success. It was concluded that member institutions in the Florida Faculty Development Consortium were investing in faculty development and providing faculty developers with dedicated time to attend to faculty development responsibilities. Member institutions were evaluating their efforts on strategic, goal-based criteria, but little evidence existed that they were evaluating based on measurable criteria
An evaluation of the antioxidant and antimicrobial properties of bee products commercially available in the UK
Bee products such as honey and propolis have been used medicinally for centuries. More recent research has seen specific types of honey such as manuka honey used in wound healing and propolis as a constituent of mouthwashes and throat lozenges. The present study determined the antioxidant and antimicrobial activities of a number of widely available bee products in the UK. The disc diffusion method was utilised to assess the antibacterial activity of the bee products using a range of bacteria known to cause infection in humans. The ferric- reducing antioxidant power (FRAP) assay was utilised to assess the antioxidant activity of the bee products. The results demonstrated that bee products had antibacterial and antioxidant capacity but with considerable variation. The most potent effect was observed using manuka 30+ against S.epidermidis (33mm mean zone of inhibition when applied undiluted compared to 11mm when using standard honey). Other bee products were of much less potency including propolis which demonstrated no significant antimicrobial activity. However, the antioxidant capacity of propolis tablets was 95 µmol/l per 1mg/ml (95,000 µmol/l per 1 gram tablet). The most potent honey tested was manuka 30+ which was 9.0 µmol/l per 1mg/ml (4500µmol/l for a 5g portion) compared with standard honey 5.0 µmol/l per 1mg/ml (2500 µmol/l for a 5g portion).The antioxidant activity of propolis was also demonstrated in human saliva. The FRAP value of the saliva from a single human subject was evaluated following the intake of propolis containing lozenges compared with a control (boiled sweet). These biological effects may be significant in vivo and have particular relevant in the prevention in disease in humans. However, further work is needed in the form of randomised controlled trials
Radar-based analysis approach for the characterization of plasma turbulence in the ionosphere
Thesis (M.S.)--Boston UniversityUnderstanding the space environment, through the study of earth's ionosphere, is essential for understanding and designing today's complex communication systems. This thesis focuses on utilizing recent advances in signal processing towards the characterization of ionospheric plasma turbulence. Previous theoretical work, by Kuo and Lee, predicts that plasma turbulence induced by the parametric decay instability propagates downward once it is excited. Unfortunately, due to limitations in altitude resolution on available radar systems, previous experimental work produced only limited evidence supporting this theory.
My thesis focuses on proving Kuo and Lee's theory through utilizing quadric time-frequency distributions, specifically the Wigner-Ville Distribution. This analysis approach allows one to analyze the backscattered energy as a function of time at an inter-pulse level. The resulting fine time resolution allows me to observe the flow of energy between the coarse altitude bins and subsequently infer the propagation direction of the instability. Using this Energy-Flow Analysis technique on experimental data collected in Alaska on August 6 - 9, 2012, I observed downward propagating turbulence that further substantiates the theory by Kuo and Lee
Open Space Acquisitions and Management Opportunities in the City of Atlanta and Adjacent Jurisdictions
The great cities of the world are distinguished by their public parks. The urban fabric of New York, Barcelona, Berlin, Moscow, Paris, Rome, Sydney, and Shanghai are all woven around great parks. Yet, with all of Atlanta's outstanding achievements, the City and the region have a notably undistinguished park system. In a study conducted by the Trust for Public Land and the Urban Land Institute, Atlanta ranks near the bottom of the nation's largest 25 cities in acreage of parkland per capita with 7.3 acres for every 1,000 residents. Compare that to Austin, Texas' 39 acres per 1,000 residents or Oklahoma City's 43 acres per 1,000 residents and it becomes clear that something is amiss in metro Atlanta.This study identifies the obstacles to acquiring and maintaining open and green spaces in the metro Atlanta region. Addressing open space shortages in metro Atlanta is a sizable task. This study could be considered the first step in a larger process. Time spent researching the various obstacles and opportunities regarding open space acquisition raised many questions that are beyond the scope of this project. A second phase might test the recommendations made in this phase by working with local officials on a few select projects, and begin to identify critical pieces of property in metro Atlanta that must be protected from development. A detailed inventory of significant open space and natural resources in the metro area that includes the existing inventory of land inside of Interstate 285 should be considered either as a separate study or included in this recommended second phase
The role of endosymbionts in the evolution of haploid-male genetic systems in scale insects (Coccoidea)
There is an extraordinary diversity in genetic systems across species, but this variation remains poorly understood. In part, this is because the mechanisms responsible for transitions between systems are often unknown. A recent hypothesis has suggested that conflict between hosts and endosymbiotic microorganisms over transmission could drive the transition from diplodiploidy to systems with male haploidy (haplodiploidy, including arrhenotoky and paternal genome elimination [PGE]). Here, we present the first formal test of this idea with a comparative analysis across scale insects (Hemiptera: Coccoidea). Scale insects are renowned for their large variation in genetic systems, and multiple transitions between diplodiploidy and haplodiploidy have taken place within this group. Additionally, most species rely on endosymbiotic microorganisms to provide them with essential nutrients lacking in their diet. We show that species harboring endosymbionts are indeed more likely to have a genetic system with male haploidy, which supports the hypothesis that endosymbionts might have played a role in the transition to haplodiploidy. We also extend our analysis to consider the relationship between endosymbiont presence and transitions to parthenogenesis. Although in scale insects there is no such overall association, species harboring eukaryote endosymbionts were more likely to be parthenogenetic than those with bacterial symbionts. These results support the idea that intergenomic conflict can drive the evolution of novel genetic systems and affect host reproduction.Peer reviewe
The old rules no longer apply: explaining Narco-assassinations of Mexican politicians
Between 2005 and 2015, organized criminal groups murdered 209 politicians in Mexico. This paper explains why. It argues that the two interwoven trends of political and criminal pluralization in Mexico fostered the conditions for a new type of criminal violence against politicians. Mexican politicians are now targeted for accepting illicit money as well as for standing up to criminals. Moreover, this violence is evidence of an alarming and persistent pattern in Mexico of politicians enlisting criminal organizations to eliminate their political competition. Using a zero-inflated negative binomial model, this paper shows there is a strong statistical relationship between the increase in assassinations and the increases in political pluralization and criminal fragmentation. The article concludes that the failure to protect local public officials creates greater opportunities for the emergence of subnational authoritarian enclaves and threatens democratic consolidation.Entre el 2005 y 2015, el crimen organizado asesinó a 209 políticos Mexicanos. Este artículo argumenta que el entrelace entre las tendencias de pluralización política y criminal crearon las condiciones para la emergencia de un nuevo tipo de violencia política en México. Actualmente, los políticos mexicanos corren riesgo tanto por aceptar dinero ilícito, como por afrontar el crimen organizado. Esto refleja un patrón alarmante y persistente en México donde los políticos corruptos usan el crimen organizado para ejecutar sus actividades ilícitas y para eliminar su competencia política. Utilizando un modelo binomial cero-inflado negativo, se muestra la correlación entre el aumento del numero de asesinatos y la magnitud de pluralización política y fragmentación criminal. En conclusión, carencias en la protección de funcionarios públicos locales han generado oportunidades para el surgimiento de enclaves autoritarios subnacionales, que últimamente debilitan la consolidación democrática
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