Multiplication Operators on Weighted Banach Spaces of a Tree

We study multiplication operators on the weighted Banach spaces of an infinite tree. We characterize the bounded and the compact operators, as well as determine the operator norm. In addition, we determine the spectrum of the bounded multiplication operators and characterize the isometries. Finally, we study the multiplication operators between the weighted Banach spaces and the Lipschitz space by characterizing the bounded and the compact operators, determine estimates on the operator norm, and show there are no isometries

Land Grant Application- Allen, Isaac (Minot)

Land grant application submitted to the Maine Land Office for Isaac Allen for service in the Revolutionary War.https://digitalmaine.com/revolutionary_war_me_land_office/1020/thumbnail.jp

Representations of Male Homosexuality in the Local Memphis News Media

This thesis sought to examine the local Memphis news media for the visibility of gay men and their accompanying representations. The study intends to note the visibility of gay men within the local media and analyze what these representations communicate about male homosexuality and its acceptance within Memphis-area society. Drawing on scholarship involving lesbian, gay, bisexual, and transgender (LGBT) visibility and representations of groups of people in the media, specifically those involving gay men, this study posed a content analysis of the local Memphis news media for the inclusion of representations of gay male individuals. One daily broadcast from each of the four local networks and the daily issue of the city\u27s most popular newspaper were surveyed for three separate, one week periods. The results of this study yielded a small number of contentious, but mostly unsurprising implications about the visibility of gay men within the local Memphis news media

Cooperation and the Fate of Microbial Societies

Microorganisms have been cooperating with each other for billions of years: by sharing resources, communicating with each other, and joining together to form biofilms and other large structures. These cooperative behaviors benefit the colony as a whole; however, they may be costly to the individuals performing them. This raises the question of how such cooperation can arise from natural selection. Mathematical modeling is one important avenue for exploring this question. Evolutionary experiments are another, providing us with an opportunity to see evolutionary dynamics in action and allowing us to test predictions arising from mathematical models. A new study in this issue of PLOS Biology investigates the evolution of a cooperative resource-sharing behavior in yeast. Examining the competition between cooperating and “cheating” strains of yeast, the authors find that, depending on the initial mix of strains, this yeast society either evolves toward a stable coexistence or collapses for lack of cooperation. Using a simple mathematical model, they show how these dynamics arise from eco-evolutionary feedback, where changes in the frequencies of strains are coupled with changes in population size. This study and others illustrate the combined power of modeling and experiment to elucidate the origins of cooperation and other fundamental questions in evolutionary biology.MathematicsOrganismic and Evolutionary Biolog

African financial systems: A review

AbstractWe start by providing an overview of financial systems in the African continent. We then consider the regions of Arab North Africa, West Africa, East and Central Africa, and Southern Africa in more detail. The paper covers, among other things, central banks, deposit-taking banks, non-bank institutions, such as the stock markets, fixed income markets, insurance markets, and microfinance institutions

African Financial Systems: A Review

We start by providing an overview of financial systems in the African continent. We then consider the regions of Arab North Africa, West Africa, East and Central Africa, and Southern Africa in more detail. The paper covers, among other things, central banks, deposit-taking banks, non-bank institutions, such as the stock markets, fixed income markets, insurance markets, and microfinance institutions

The effect of one additional driver mutation on tumor progression

Tumor growth is caused by the acquisition of driver mutations, which enhance the net reproductive rate of cells. Driver mutations may increase cell division, reduce cell death, or allow cells to overcome density-limiting effects. We study the dynamics of tumor growth as one additional driver mutation is acquired. Our models are based on two-type branching processes that terminate in either tumor disappearance or tumor detection. In our first model, both cell types grow exponentially, with a faster rate for cells carrying the additional driver. We find that the additional driver mutation does not affect the survival probability of the lesion, but can substantially reduce the time to reach the detectable size if the lesion is slow growing. In our second model, cells lacking the additional driver cannot exceed a fixed carrying capacity, due to density limitations. In this case, the time to detection depends strongly on this carrying capacity. Our model provides a quantitative framework for studying tumor dynamics during different stages of progression. We observe that early, small lesions need additional drivers, while late stage metastases are only marginally affected by them. These results help to explain why additional driver mutations are typically not detected in fast-growing metastases.MathematicsOrganismic and Evolutionary Biolog

Effect of pretreatment temperature on the surface modification of diatomite with trimethylchlorosilane

Artículo científicoDiatomite samples from Costa Rica were purified using acidic treatments with hydrochloric acid, thermally treated (400–1000 C) and then silylated with trimethylchlorosilane in toluene under inert atmosphere. The purification process allows to decrease the concentration of metals presented in the crude diatomite, as is confirmed by X-ray Fluorescence (XRF) Analysis. The silylated materials were analyzed by using Hyperpolarized 129Xe Nuclear Magnetic Resonance Spectroscopy (HP 129Xe NMR), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), rehydration tests, and contact angle measurements. XRD measurements indicate that diatomite is mainly amorphous, but presents several crystalline phases (kaolinite, cristobalite, and quartz). Pretreatments at high temperatures cause changes in those crystalline phases, resulting in more amorphous materials. However, there is no difference in the overall structure of purified and thermally treated diatomite samples with respect to the silylation products. In addition, SEM measurements show no effect over the pore structure of the materials. On the other hand, TGA measurements and rehydration tests show lower losses of water for silylated materials prepared using higher pretreatment temperatures. Moreover, HP 129Xe NMR, FTIR, and contact angle measurements evidence a modification due to covalent attachment of Si(CH3)3-groups to the surface, which increases for higher pretreatment temperatures. The results provide valuable information about external factors that influence the surface modification of diatomite. This can be useful to control modifications that can be achieved in a similar way

Unemployment in Nigeria; A Challenge of Demographic Change?

With the current population of approximately 182million people (PRB, 2015); Nigeria is the most populous Black Country in the world. Arguments are ripe whether her ever-growing population is the sole factor responsible also for her continuous growth of unemployment. To answer this question, this paper extracted secondary data from Population Reference Bureau (PRB, 2003-2015), United Nations Annex Table (2012), International Monetary Fund (IMF, 2002-2015) and National Bureau of Statistics (NBS, 2003-2015) to prove whether unemployment is mainly caused by demographic change in Nigeria or there are other intrinsic factors responsible for this social challenge. A comparative analysis of the population and unemployment structure of three purposively selected and heavily populated countries in three different continents-Nigeria, China and USA were undertaken. Results show that population growth is not the SOLE factor responsible for increase in unemployment in Nigeria as unemployment statistics is stable for U.S. and China while their populations are growing, but the reverse is the case for Nigeria as both population and unemployment are growing. Recommendations were thereafter made to address other likely factors identified