Life history and mating systems select for male biased parasitism mediated through natural selection and ecological feedbacks

Males are often the "sicker" sex with male biased parasitism found in a taxonomically diverse range of species. There is considerable interest in the processes that could underlie the evolution of sex-biased parasitism. Mating system differences along with differences in lifespan may play a key role. We examine whether these factors are likely to lead to male-biased parasitism through natural selection taking into account the critical role that ecological feedbacks play in the evolution of defence. We use a host-parasite model with two-sexes and the techniques of adaptive dynamics to investigate how mating system and sexual differences in competitive ability and longevity can select for a bias in the rates of parasitism. Male-biased parasitism is selected for when males have a shorter average lifespan or when males are subject to greater competition for resources. Male-biased parasitism evolves as a consequence of sexual differences in life history that produce a greater proportion of susceptible females than males and therefore reduce the cost of avoiding parasitism in males. Different mating systems such as monogamy, polygamy or polyandry did not produce a bias in parasitism through these ecological feedbacks but may accentuate an existing bias.Comment: 18 pages, 4 figure

The Representation of Cultural Content in Global Elementary Coursebook

This study was to find out the types of cultural content source found in the reading and listening texts presented in Global elementary coursebook (2012) and the similarities and differences of the types of cultural content source found in those texts. The data were analyzed using the theory of types of cultural content source proposed by Matsuda (2012). The findings of this study showed that the reading texts met 54.9% of global culture, 35.3% of target culture, and 9.8% of local culture while the listening texts met 72.5% of global culture, 25% of target culture, and 2.5% of local culture. All in all, as proposed by Matsuda (2012), a good coursebook is the one that has multiple sources of cultural content; and Global elementary coursebook fulfills this criterion as it has three types of cultural content source

An approach for configuring space photovoltaic tandem arrays based on cell layer performance

Meeting solar array performance goals of 300 W/Kg requires use of solar cells with orbital efficiencies greater than 20 percent. Only multijunction cells and cell layers operating in tandem produce this required efficiency. An approach for defining solar array design concepts that use tandem cell layers involve the following: transforming cell layer performance at standard test conditions to on-orbit performance; optimizing circuit configuration with tandem cell layers; evaluating circuit sensitivity to cell current mismatch; developing array electrical design around selected circuit; and predicting array orbital performance including seasonal variations

A Model of Vascular Tumor Response to Chemotherapy Combined with Anti-Angiogenic Therapy

Flora S. Bacelar... et al.Angiogenesis is acknowledged as an essential mechanism for tumor spreading and metastasis of neoplastic diseases. Consequently, anti-angiogenic therapy has been proposed as a complementary or perhaps an alternative strategy to the traditional cytotoxic therapies. This work considers a model of ordinary di®erential equations that describe the dynamics of tumors at the vascular stage (after the angiogenic process has been triggered), under the action of chemical and anti-angiogenic ther- apies. Due to the increase of endothelial cells at the vascular stage, the cancer state prevails over the internal state in the no treatment situation. Results from the lo- cal stability analysis and numerical integration, indicate that the combination of chemotherapy and anti-angiogenic therapy is the best strategy to eliminate the tu- mor, reducing the cytotoxic e®ect. At a ¯xed infusion rate, the cure state may be reached when the combined therapy is considered but not for the anti-angiogenic therapy only. On the other hand, pure chemotherapy efectively destroys the tumor, but only when higher infusion doses are applied.Acknowledgments: STRP, RFSA thank CNPq for partial supporting the re- searchPeer reviewe

Implementation Of Drta (Directed Reading Thinking Activity) In Increasing Students' Reading Achievement

Tujuan penelitian ini adalah untuk mengetahui apakah ada perbedaan terhadap nilai membaca siswa dalam teks naratif sebelum dan setelah diajarkan melalui teknik DRTA dan untuk mengetahui apakah ada peningkatan dari nilai pemahaman membaca siswa dalam teks naratif setelah diajarkan melalui teknik DRTA. Penelitian ini menggunakan pendekatan kuantitatif dan melibatkan kelas XI Lintas Minat 3. Tes pemahaman membaca diberikan untuk mengumpulkan data. Hasil analisis data menunjukan bahwa ada perbedaan dari nilai membaca siswa setelah diajarkan dengan menggunakan teknik DRTA. Hal ini dapat dibuktikan dari adanya peningkatan nilai rata-rata siswa dari pretes ke postes yaitu 65.32 naik menjadi 77.95 dan peningkatannya adalah 12.36. Selain itu uji hipotesis menunjukan t-value lebih tinggi dari t-table (15.111 > 2.080). Oleh sebab itu dapat disimpulkan ada peningkatan yang signifikan dari nilai membaca siswa setelah diajarkan melalui teknik DRTA.The aims of this research were to find out whether there was a difference of students' reading comprehension achievement of narrative text before and after being taught through DRTA technique and to find out whether there was an increase of students' reading comprehension achievement of narrative text after being taught through DRTA technique. Quantitative approach was conducted in class XI LM 3. Reading comprehension test was administered to collect the data. The result of the data analysis showed that there was a difference of students' reading achievement after being taught through DRTA. It could be proven from the increase of students' mean score from pre-test to post-test, which was 65.32 up to 77.95, and the gain was 12.36. Besides, the hypothesis test showed t-value was higher than t-table (15.111>2.080). Therefore, it can be concluded that there was a significant increase of students' reading achievement after being taught through DRTA technique

Mechanistic Approaches To The Prevention Of Mutation And Cancer

Cancer and other mutation-related diseases can be prevented at three levels: primary prevention, which is addressed to healthy individuals in order to prevent occurrence of the disease; secondary prevention, which is addressed to early stage patients in order to prevent progression of the disease; and tertiary prevention, which is addressed to patients after therapy in order to prevent relapses of the disease. Although the most obvious approach to prevention is to minimize exposures to recognized risk factors, a complementary strategy is represented by chemoprevention, using dietary and pharmacological agents that reinforce the host defence machinery. Since 1988, I proposed detailed classifications of mechanisms of inhibitors of mutagenesis and carcinogenesis. They may apply not only to cancer but also to other degenerative diseases that have replaced infectious diseases as the leading causes of death in the population. In fact, certain mechanisms, such as damage to nuclear DNA and mtDNA, oxidative stress, chronic inflammation, signal transduction alterations and epigenetic changes may be involved in the pathogenesis of different diseases. Studies performed in our laboratory have shown that certain genomic alterations that are usually investigated in cancer research may also be detected in other chronic diseases, such as atherosclerosis, degenerative heart diseases, chronic obstructive pulmonary diseases, neurological disorders, eye diseases, skin ageing, and alopecia. Similar alterations were investigated in critical periods of life, such as birth and ageing. The nucleotide alterations occurring at birth in the lung render the newborn particularly vulnerable to the action of environmental agents. In fact, we demonstrated that cigarette smoke becomes a potent carcinogen in mice when exposure starts at birth and continues early in life. We investigated a number of chemopreventive agents by evaluating modulation of intermediate biomarkers and carcinogenicity. An optimal agent should not excessively alter the physiological patterns of gene expression, microRNA and proteome profiles, but at the same time it should be effective in inhibiting alterations induced by mutagens and carcinogens. It should be noted that most chemopreventive agents possess pleiotropic properties. The knowledge of mechanisms can be exploited to combine different agents working with complementary mechanisms. Like the therapy of important diseases, such as cancer, cardiovascular diseases, AIDS, etc., uses combinations of drugs, combined chemoprevention is a quite promising strategy. Although a large number of agents are potentially able to prevent cancer, we are in search of tools to predict, hopefully in the single individual, their efficacy and safety in humans

A Comparison of Student Retention and First Year Programs Among Liberal Arts Colleges in the Mountain South

Abstract is available to download