scholarly journals Impact of low sperm competition on male reproductive trait allometries in a bush-cricket

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Lennart Winkler ◽  
Leon M. Kirch ◽  
Klaus Reinhold ◽  
Steven A. Ramm
Keyword(s):  
Sperm Competition ◽  
Morphological Structure ◽  
Investment Strategy ◽  
Reproductive Trait ◽  
Investment Strategies ◽  
Male Investment ◽  
Subgenital Plate ◽  
Potential Alternative ◽  
The One ◽  
Bush Cricket

Abstract Background Studying reproductive trait allometries can help to understand optimal male investment strategies under sexual selection. In promiscuous mating systems, studies across several taxa suggest that testes allometry is usually positive, presumably due to strong selection on sperm numbers through intense sperm competition. Here, we investigated testes allometry in a bush-cricket species, Metaplastes ornatus, in which females mate promiscuously, but where sperm removal behaviour by males likely drastically reduces realised sperm competition level. Results As hypothesised, we found evidence for negative testes allometry and hence a fundamentally different male investment strategy compared to species under intense sperm competition. In addition, the mean relative testes size of M. ornatus was small compared to other species of bush-crickets. Surprisingly, the spermatophore gland, a potential alternative trait that males could invest in instead of testes, also did not show positive allometry, but was approximately isometric. We further observed the expected pattern of negative allometry for the male morphological structure responsible for sperm removal in this species, the subgenital plate, supporting the one-size-fits-all hypothesis for intromittent genitalia. Conclusion Our findings suggest that the evolution of sperm removal behaviour in M. ornatus was a key adaptation for avoiding sperm competition, with important consequences for reproductive trait allometries. Nevertheless, they also imply that it does not pay for larger males to invest disproportionately in nuptial gift production in this species.

Investment Strategies for Sourcing a New Technology in the Presence of a Mature Technology

2021 ◽  
Author(s):  
Wei Zhang ◽  
Hsiao-Hui Lee
Keyword(s):  
Operations Management ◽  
New Technologies ◽  
New Technology ◽  
Investment Strategy ◽  
Profit Sharing ◽  
Development Effort ◽  
Investment Strategies ◽  
Cost Shifting ◽  
The One ◽  
The Cost

To stay competitive, high-technology manufacturers not only frequently source new technologies from their suppliers, but also financially support the development of these new technologies into component products or production tools. We consider a manufacturer that can either source a new but immature technology from a financially constrained supplier, or source a mature technology from an existing supplier if and only if the development of the new technology fails. To support the new technology, the manufacturer can choose to inject capital in the form of an equity or loan. The investment strategy not only affects the new supplier’s development effort and the probability of technical success (PTS), but also affects the existing supplier’s effort to improve the mature technology, which presents the manufacturer with a trade-off. Following the debt financing literature, we find that a loan contract is associated with a cost-shifting effect and often leads to a higher PTS. However, because the manufacturer not only maintains an investment but also a procurement relationship with the new supplier, we find a profit-sharing effect associated with an equity investment, which does not exist in the traditional equity issuance literature. In particular, we show that the profit-sharing effect can dominate the cost-shifting effect and lead to a higher PTS when the new supplier’s technological capability is sufficiently high. Nonetheless, we also show that the strategy that derives a higher PTS does not necessarily generate a higher payoff for the manufacturer. On the one hand, a loan can be preferred even when it leads to a lower PTS because the cost-shifting effect allows the manufacturer to offer a sufficiently low procurement payment while maintaining a sufficiently high PTS. On the other hand, when the existing supplier is very capable of reducing its costs, a loan can over-incentivize the new supplier to exert excessive effort and backfire. This paper was accepted by Charles Corbett, operations management.

Mutual fund management in the period of financial crisis

2017 ◽  
Vol 31 (2) ◽  
pp. 75-81
Author(s):  
О. А. Bank
Keyword(s):  
Financial Crisis ◽  
Mutual Fund ◽  
Economic Recession ◽  
Investment Strategy ◽  
Economic Conditions ◽  
Investment Strategies ◽  
Fixed Income ◽  
Fund Management ◽  
Fund Managers ◽  
Different Types

Mutual fund managers do not have full freedom in choosing investment strategies - they are limited both by the laws and by investment declarations of the funds. Investment strategy cannot be fully changed even in financial crisis but it only can be corrected. This fact could not be characterized as a disadvantage because different types of funds are efficient in different time even during the same economic recession. Mutual fund manager should rationally invest funds of their clients: it is better to keep the maximum possible part of the portfolio in cash and instruments with fixed income on the declining market and it is better to keep shares on the rising market. However the choice of bonds also as the choice of shares should pay respect for the features of these instruments during unfavorable economic conditions. Russian mutual fund management differs from fund management in other countries as in stable economic situation so in the circumstances of financial crisis.

scholarly journals Probability density functions of long-lived tracer observations from satellite in the subtropical barrier region: data intercomparison

2011 ◽  
Vol 11 (20) ◽  
pp. 10579-10598 ◽  
Author(s):  
E. Palazzi ◽  
F. Fierli ◽  
G. P. Stiller ◽  
J. Urban
Keyword(s):  
Michelson Interferometer ◽  
Morphological Structure ◽  
Quasi Biennial Oscillation ◽  
Temporal Sampling ◽  
Region Data ◽  
Summer Hemisphere ◽  
Consistent Picture ◽  
Transport And Mixing ◽  
The One ◽  
Satellite Instruments

Abstract. Past studies have shown that a clear relationship exists between the field of a passive tracer and the Probability Distribution Function (PDF) of tracer concentrations, which can be exploited to identify the position and variability of stratospheric barriers to isentropic mixing. In the present study, we focus on the dynamical barrier located in the subtropics. We calculate PDFs of the long-lived tracers nitrous oxide (N2O) and methane (CH4) from different satellite instruments: the Microwave Limb Sounder (MLS) on board Aura, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board Envisat, the Sub-Millimetre Radiometre (SMR) on board Odin and the Halogen Occultation Experiment (HALOE) on board UARS, overall covering the time period of 1992–2009. An analysis of the consistency among the different sets of data and their capability of identifying mixing regions and barrier-to-transport regions in the stratosphere and the subtropical barrier location is a prime aim of the present study. This is done looking at the morphological structure of the one- and two-dimensional PDFs of tracer concentrations measured by the different instruments. The latter differ in their spatial and temporal sampling and resolution, and there are some systematic differences in the determination of the subtropical barrier position that have been highlighted. However, the four satellite instruments offer an overall consistent picture of the subtropical barrier annual cycle. There is a strong seasonality consistently represented, characterized by the wintertime shift of the subtropical edge toward the summer hemisphere. However, the influence of the Quasi Biennial Oscillation (QBO) on isentropic transport and mixing, and by consequence, on the position of the subtropical barrier, is not equally represented in all satellite data using the methodology proposed.

scholarly journals Effectiveness of Selected Investment Strategies in the Opinion of Polish Individual Investors Depending on their Personal Preferences

2020 ◽  
Vol 13 (4) ◽  
pp. 442-451
Author(s):  
Katarzyna Daniluk
Keyword(s):  
Risk Aversion ◽  
Investment Strategy ◽  
Capital Allocation ◽  
Survey Method ◽  
Individual Investors ◽  
Investment Horizon ◽  
Investment Strategies ◽  
Research Material ◽  
Individual Needs ◽  
Level Of Risk

SummarySubject and purpose of work: The work aimed at identifying and characterising the interdependence between Polish investors’ personal preferences in investing and their opinion about the effectiveness of investment strategies. It was examined how the adopted investment horizon, the level of risk aversion and the time spent daily on investing impact the interviewees’ experiences and opinions on the effectiveness of investment strategies.Materials and methods: As the survey method was employed, a questionnaire was sent to randomly selected Polish individual investors. The research material consisted of 652 questionnaire forms.Results: The study showed a relevant dependence between Polish investors’ personal preferences and their opinions on the effectiveness of the particular strategies.Conclusions: The interdependencies revealed in the study may be used by potential investors in the process of matching a strategy to individual needs so as to enhance the effectiveness of the choice. A higher awareness of the problem of matching an investment strategy to personal preferences will lead to improved effectiveness of capital allocation among Polish investors.

Bacteriophages: from isolation to application

2021 ◽  
Vol 22 ◽  
Author(s):  
Abdallah S. Abdelsattar ◽  
Alyaa Dawoud ◽  
Salsabil Makky ◽  
Rana Nofal ◽  
Ramy K. Aziz ◽  
...  
Keyword(s):  
Food Industry ◽  
Pathogenic Bacteria ◽  
Phage Genome ◽  
Morphological Structure ◽  
High Specificity ◽  
Potential Alternative ◽  
And Behavior ◽  
Phage Isolation ◽  
Different Levels ◽  
Selection Of

: Bacteriophages are considered as a potential alternative to fight pathogenic bacteria during the antibiotic resistance era. With their high specificity, they are being widely used in various applications: medicine, food industry, agriculture, animal farms, biotechnology, diagnosis, etc. Many techniques have been designed by different researchers for phage isolation, purification, and amplification, each of which has strengths and weaknesses. However, all aim at having a reasonably pure phage sample that can be further characterized. Phages can be characterized based on their physiological, morphological or inactivation tests. Microscopy, in particular, has opened a wide gate not only for visualizing phage morphological structure, but also for monitoring biochemistry and behavior. Meanwhile, computational analysis of phage genomes provides more details about phage history, lifestyle, and potential for toxigenic or lysogenic conversion, which translate to safety in biocontrol and phage therapy applications. This review summarizes phage application pipelines at different levels and addresses specific restrictions and knowledge gaps in the field. Recently developed computational approaches, which are used in phage genome analysis, are critically assessed. We hope that this assessment provides researchers with useful insights for selection of suitable approaches for Phage-related research aims and applications.

scholarly journals Antimicrobial Efficacy of Fruit Peels Eco-Enzyme against Enterococcus faecalis: An In Vitro Study

2020 ◽  
Vol 17 (14) ◽  
pp. 5107
Author(s):  
Hetal Ashvin Kumar Mavani ◽  
In Meei Tew ◽  
Lishen Wong ◽  
Hsu Zenn Yew ◽  
Alida Mahyuddin ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Inhibitory Concentration ◽  
Antimicrobial Properties ◽  
In Vitro Study ◽  
Antimicrobial Effect ◽  
Antimicrobial Efficacy ◽  
Significant Difference ◽  
Potential Alternative ◽  
The One

Sodium hypochlorite (NaOCl), an effective endodontic irrigant against Enterococcus faecalis (EF), is harmful to periapical tissues. Natural pineapple-orange eco-enzymes (M-EE) and papaya eco-enzyme (P-EE) could be potential alternatives. This study aimed to assess the antimicrobial efficacy of M-EE and P-EE at different concentrations and fermentation periods against EF, compared to 2.5% NaOCl. Fermented M-EE and P-EE (3 and 6 months) at various concentrations were mixed with EF in a 96-well plate incubated for 24 h anaerobically. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of M-EE and P-EE were determined via EF growth observation. EF inhibition was quantitatively measured and compared between different irrigants using the one-way analysis of variance (ANOVA), and different fermentation periods using the independent-samples T-test. M-EE and P-EE showed MIC at 50% and MBC at 100% concentrations. There was no significant difference in antimicrobial effect when comparing M-EE and P-EE at 50% and 100% to 2.5% NaOCl. P-EE at 6 months fermentation exhibited higher EF inhibition compared to 3 months at concentrations of 25% (p = 0.017) and 0.78% (p = 0.009). The antimicrobial properties of M-EE and P-EE, at both 100% and 50% concentrations, are comparable to 2.5% NaOCl. They could therefore be potential alternative endodontic irrigants, but further studies are required.

scholarly journals Seminal fluid and accessory male investment in sperm competition

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200068
Author(s):  
Steven A. Ramm
Keyword(s):  
Sperm Competition ◽  
Seminal Fluid ◽  
Complex Mixture ◽  
Internal Fertilization ◽  
Animal Evolution ◽  
Male Investment ◽  
Trade Offs ◽  
Fluid Production ◽  
Alternative Routes ◽  
Paternity Success

Sperm production and allocation strategies have been a central concern of sperm competition research for the past 50 years. But during the ‘sexual cascade’ there may be strong selection for alternative routes to maximizing male fitness. Especially with the evolution of internal fertilization, a common and by now well-studied example is the accessory ejaculate investment represented by seminal fluid, the complex mixture of proteins, peptides and other components transferred to females together with sperm. How seminal fluid investment should covary with sperm investment probably depends on the mechanism of seminal fluid action. If seminal fluid components boost male paternity success by directly enhancing sperm function or use, we might often expect a positive correlation between the two forms of male investment, whereas trade-offs seem more likely if seminal fluid acts independently of sperm. This is largely borne out by a broad taxonomic survey to establish the prevailing patterns of seminal fluid production and allocation during animal evolution, in light of which I discuss the gaps that remain in our understanding of this key ejaculate component and its relationship to sperm investment, before outlining promising approaches for examining seminal fluid-mediated sperm competitiveness in the post-genomic era. This article is part of the theme issue ‘Fifty years of sperm competition’.

Analyzing the Influences of Passive Investment Strategies on Financial Markets via Agent-Based Modeling

2008 ◽  
pp. 224-238 ◽  
Author(s):  
Hiroshi Takahashi ◽  
Satoru Takahashi ◽  
Takao Terano
Keyword(s):  
Asset Pricing ◽  
Financial Markets ◽  
Financial Market ◽  
Investment Strategy ◽  
Agent Based Modeling ◽  
Investment Strategies ◽  
Agent Based Model ◽  
Efficient Market ◽  
Agent Based ◽  
Price Fluctuations

This chapter develops an agent-based model to analyze microscopic and macroscopic links between investor behaviors and price fluctuations in a financial market. This analysis focuses on the effects of Passive Investment Strategy in a financial market. From the extensive analyses, we have found that (1) Passive Investment Strategy is valid in a realistic efficient market, however, it could have bad influences such as instability of market and inadequate asset pricing deviations, and (2) under certain assumptions, Passive Investment Strategy and Active Investment Strategy could coexist in a Financial Market.

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