The paradox of enrichment, spatial heterogeneity, community effects and the phenomenon of apparent disappearance in the marine bacteriophage dynamics

2021 ◽  
Vol 62 ◽  
pp. 453-468
Author(s):  
Andrei Korobeinikov ◽  
Elena Shchepakina ◽  
Vladimir Sobolev Sobolev
Keyword(s):  
Mathematical Model ◽  
Hopf Bifurcation ◽  
External Factors ◽  
Loss Of Stability ◽  
Simple Mathematical Model ◽  
Community Effects ◽  
Periodic Forcing ◽  
Internal Factors ◽  
High Magnitude ◽  
Microbial Systems

In aquatic microbial systems, high magnitude variations in abundance, such as sudden blooms alternating with comparatively long periods of very low abundance ("apparent disappearance'') are relatively common. The authors suggest that, in order to occur, such variations in abundance in microbial systems and, in particular, the apparent disappearance of species do not require seasonal or periodic forcing of any kind, or external factors of any other nature, and can be caused by internal factors, and in particular by bacteria-phage interaction. Specifically, the authors suggest that the variations in abundance and the apparent disappearance phenomenon can be a result of phage infection and the lysis of infected bacteria. To illustrate this idea, the authors consider a reasonably simple mathematical model of bacteria-phage interaction based on the model suggested by Edoardo Beretta and Yang Kuang, which assumes neither periodic forcing, nor action of other external factors. The model admits a loss of stability via Andronov-Hopf bifurcation and exhibits dynamics which is able to explains the phenomenon. These properties of the model are especially distinctive for spatially non-homogeneous biosystems as well as biosystem with some sorts of cooperation or community effects. doi:10.1017/S1446181120000085

THE PARADOX OF ENRICHMENT, SPATIAL HETEROGENEITY, COMMUNITY EFFECTS AND THE PHENOMENON OF APPARENT DISAPPEARANCE IN THE MARINE BACTERIOPHAGE DYNAMICS

2020 ◽  
pp. 1-16
Author(s):  
ANDREI KOROBEINIKOV ◽  
ELENA SHCHEPAKINA ◽  
VLADIMIR SOBOLEV
Keyword(s):  
Mathematical Model ◽  
Hopf Bifurcation ◽  
External Factors ◽  
Loss Of Stability ◽  
Simple Mathematical Model ◽  
Community Effects ◽  
Periodic Forcing ◽  
Internal Factors ◽  
High Magnitude ◽  
Microbial Systems

In aquatic microbial systems, high-magnitude variations in abundance, such as sudden blooms alternating with comparatively long periods of very low abundance (“apparent disappearance”), are relatively common. We suggest that in order for this to occur, such variations in abundance in microbial systems and, in particular, the apparent disappearance of species do not require seasonal or periodic forcing of any kind or external factors of any other nature. Instead, such variations can be caused by internal factors and, in particular, by bacteria–phage interaction. Specifically, we suggest that the variations in abundance and the apparent disappearance phenomenon can be a result of phage infection and the lysis of infected bacteria. To illustrate this idea, we consider a reasonably simple mathematical model of bacteria–phage interaction based on the model suggested by Beretta and Kuang, which assumes neither periodic forcing nor action of other external factors. The model admits a loss of stability via Andronov–Hopf bifurcation and exhibits dynamics which explains the phenomenon. These properties of the model are especially distinctive for spatially nonhomogeneous biosystems as well as biosystems with some sort of cooperation or community effects.

scholarly journals HOPF BIFURCATION ANALYSIS FOR A MATHEMATICAL MODEL OF P53-MDM2 INTERACTION

2008 ◽  
Vol 18 (01) ◽  
pp. 275-283 ◽  
Author(s):  
MIHAELA NEAMŢU ◽  
RAUL FLORIN HORHAT ◽  
DUMITRU OPRIŞ
Keyword(s):  
Mathematical Model ◽  
Hopf Bifurcation ◽  
Numerical Simulations ◽  
Periodic Solutions ◽  
Stationary State ◽  
Bifurcation Analysis ◽  
Local Stability ◽  
Bifurcation Parameter ◽  
Simple Mathematical Model

In this paper we analyze a simple mathematical model which describes the interaction between proteins P53 and Mdm2. For the stationary state we discuss the local stability and the existence of a Hopf bifurcation. We study the direction and stability of the bifurcating periodic solutions by choosing the delay as a bifurcation parameter. Finally, we will offer some numerical simulations and present our conclusions.

Kegunaan Informasi Akuntansi dalam Pengambilan Keputusan Internal oleh Unit Akuntansi Kuasa Pengguna Anggaran (UAKPA)

2017 ◽  
Vol 2 (4) ◽  
pp. 73-91
Author(s):  
Karno Pandu Wibowo
Keyword(s):  
Decision Making ◽  
Accounting Information ◽  
Information Use ◽  
External Factors ◽  
Accrual Accounting ◽  
Related Factors ◽  
Internal Factors ◽  
Level Of Use ◽  
Accrual Basis ◽  
Cash Basis

This study aims to determine the usefulness level of accounting information (on cash basis and accrual basis) in central goverment agencies internal decision-making process. In addition, this study also aims to determine the influence of the organization’s external factors, the organization's internal factors and Individual Actor’s Characteristic Related Factors on the level of use of accounting information in central goverment agencies internal decision making.The research show that  level of accrual accounting information use in the context of internal decision making is high. In addition it showed differences between  level of cash-based accounting information use and accrual-based accounting information use. This study also addressed that the organization’s external factors, the organization's internal factors and individual actor’s characteristic related factors significantly influence both level of accounting information use  on cash basis and accrual basis in the internal decision-making. Except for the organization’s external factors  did not significantly affect the level of accrual accounting information use  in the internal decision-making.   Abstrak Penelitian ini bertujuan untuk mengetahui tingkat kegunaan informasi akuntansi (berbasis kas dan akrual) dalam proses pengambilan keputusan internal Unit Akuntansi Kuasa Pengguna Anggaran (UAKPA). Selain itu penelitian ini juga bertujuan untuk mengetahui pengaruh faktor eksternal organisasi, faktor internal organisasi dan faktor karakteristik individu pengguna terhadap tingkat penggunaan informasi akuntansi dalam pengambilan keputusan internal Unit Akuntansi Kuasa Pengguna Anggaran (UAKPA).Temuan peneliti menunjukan bahwa tingkat penggunaan informasi akuntansi berbasis akrual tinggi dalam rangka pengambilan keputusan internal. Selain itu penelitian menunjukan adanya perbedaan tingkat penggunaan antara informasi akutansi berbasis kas dan informasi akutansi berbasis akrual. Penelitian juga menujukan bahwa faktor eksternal organisasi, faktor internal organisasi dan faktor karakteristik individu pengguna berpengaruh signifikan terhadap tingkat penggunaan informasi akuntansi (berbasis kas dan akrual) dalam pengambilan keputusan internal. Kecuali untuk faktor eksternal organisasi tidak berpengaruh signifikan terhadap tingkat penggunaan informasi akuntansi akrual dalam pengambilan keputusan internal.

Pengaruh Inflasi, BI Rate, NPF, dan BOPO terhadap Profitabilitas Bank Umum Syariah di Indonesia

2018 ◽  
Vol 6 (1) ◽  
pp. 133-153
Author(s):  
Toufan Aldian Syah
Keyword(s):  
Banking Industry ◽  
External Factors ◽  
Coefficient Of Determination ◽  
Muslim Country ◽  
Internal Factors ◽  
Slowing Down ◽  
The World ◽  
Negative Effect ◽  
Test Correlation ◽  
The Ideal

Banking industry has a very important role in economic development in a country. Indonesia, which is the largest Muslim country in the world, certainly has the prospect of the development of Sharia Banking Industry is very good in the future. However, the development of Sharia Bank has been slowing down in recent years and the profitability of sharia comercial banking is still below the ideal value. This study aims to determine the internal factors and external factors that affect the profitability of Sharia Bank in the year of January 2012 until August 2017. The variables used in this study are ROA, Inflation, NPF, and BOPO. The data used is aggregate data of all Sharia Commercial Banks recorded at Bank Indonesia. Measurement of Statistic Description, F-Test, T-Test, Correlation Coefficient, Coefficient of Determination and Multiple Linear Regression using IBM SPSS 21 software. The results showed that significant negative effect of BI rate, NPF and BOPO was found, while Inflation variable showed negative but not significant. Overall, the above variables affect the ROA of 87.7%, while 12.3% is likely to be influenced by other factors.

ANALISIS PENGARUH ERUBAHAN TINGKAT SUKU BUNGA SBI DAN PERUBAHAN KURS US$ TERHADAP HARGA PASAR SAHAM SEMEN GRESIK, TBK PERIODE JANUARI 2002 – DESEMBER 2006

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Oktafalia Marisa ◽  
Maya Syafriana
Keyword(s):  
Monetary Policy ◽  
Exchange Rate ◽  
Cash Flow ◽  
Stock Price ◽  
External Factors ◽  
Investment Climate ◽  
Internal Factors ◽  
Price Fluctuation ◽  
Two Factors ◽  
Investment Behaviour

<p class="Pendahuluan">Investment climate has begun to rise since a few years ago. Stock price fluctuations keep stable and move to the positive position. Stock price fluctuation affected by two factors, internal factors and external factors. Internal factors consist of company’s cash flow, dividend and investment behaviour. External factors consist of monetary policy, exchange rate, interest volatility, globalization, companies’ competition, and technology. This research, try to find out the effects of SBI rate and exchanged rate (USD/Rp) to PT. Semen Gresik’s stock price.</p><p class="Pendahuluan"> </p><p class="Pendahuluan">Keywords : Investment, stock price, SBI’s rate, and Exchanged rate.</p>

STRATEGI MENINGKATKAN LOYALITAS KONSUMEN MAKANAN KHAS KOTA CURUP KABUPATEN REJANG LEBONG

2019 ◽  
Author(s):  
Onsardi Onsardi
Keyword(s):  
Swot Analysis ◽  
Raw Materials ◽  
External Factors ◽  
Consumer Loyalty ◽  
Internal Factors ◽  
The Public ◽  
Typical Food ◽  
Internal And External Factors

The title of this study is the Strategy of Increasing Consumer Food Loyalty in CurupCity, Rejang Lebong Regency (Case Study in "Henvian" Typical Food Industry). Thisresearch is based on the importance of strategies in increasing business and consumerloyalty to products sold.Strategies to increase business and consumer loyalty can bedone with a SWOT analysis. Place of this research is the "Henvian" shop that sellstypical Rejang lebong food. The method used in this study is descriptive qualitative.Informants in this study were people who were considered to know for certain about theHENVIAN Specialty Food Store in Curup City, Rejang Lebong Regency. The dataanalysis technique used in this study is a SWOT analysis to determine the strengths,weaknesses, opportunities and threats in a typical Rejang Lebong food business.By using SWOT analysis techniques that consist of strengths (weakness), weaknesses(weakness), opportunities (opportnity) and threats (threath). The results of this studycan be concluded that the internal factors that are the strength of the marketing strategyare the quality of the product that is good at a price affordable to the public andtourists, service that is friendly and responsive to consumer needs, as well astechnological advancements that facilitate the promotion of business. Internal factorsthat are a weakness are often lack of stock, there are some products that do not meet thestandard packaging, the product shelf life is short, employees do not use uniforms.External factors that become opportunities are a fairly high economic community,abundant raw materials while external factors that are a threat are the manycompetitors, an unstable economy, the price of basic needs increases. Based on theresults of the SWOT analysis of internal and external factors, the strategy used is toimprove product quality by improving the appearance of packaging and quality ofcontent and quality of service by providing uniforms to employees and providingstandards of service to consumers. .Keywords: Strategy, Consumer Loyalty, SWOT

Determinants of Islamic Bank Profitability: Evidence from Indonesia

2020 ◽  
Vol 5 (1) ◽  
pp. 1-13
Author(s):  
Puji Sucia Sukmaningrum ◽  
Kashan Pirzada ◽  
Sylva Alif Rusmita ◽  
Fatin Fadhilah Hasib ◽  
Tika Widiastuti ◽  
...  
Keyword(s):  
Interest Rate ◽  
Quality Management ◽  
Banking Industry ◽  
External Factors ◽  
Islamic Banking ◽  
Islamic Banks ◽  
Return On Assets ◽  
Internal Factors ◽  
Bank Profitability ◽  
Islamic Bank

Objective – Islamic Banks have a distinct advantage that is not only conduct a commercial operation, but to also conduct social operations. Therefore, Islamic Banks plays an important role in developing the Indonesian economy. The aim of this study is to investigate the impact of internal and external factors that affect the profitability of Islamic Banks in Indonesia. Methodology/Technique – The methodology of this research is multiple regression. The object of this research is the Islamic banking industry in Indonesia. Internal factors include size, liquidity, asset quality, management, and efficiency ratio. External factors include interest rate and inflation. Return on Assets is used to measure profitability. The monthly data is collected from the financial reports of Islamic Banks between 2011 to 2016. Findings – The findings show that size, liquidity, assets quality, management ratio, interest rate and inflation lead to a greater Return on Assets (profitability) in Islamic Banks in Indonesia. Efficiency however does not have a significant effect on profitability of Islamic Banks in Indonesia. Novelty – Based on the results of this research, it can be concluded that the Islamic banking industry can use those variables to improve the profitability of Islamic banks in the future. In addition, there are two variables that affect the profitability of Islamic banking industry. For the Islamic banking industry should anticipate the movement of inflation and interest to improve the profitability of Islamic banks. Type of Paper: Empirical paper. Keywords: Islamic Banks; Profitability; Internal Factors; External Factors; Indonesia. Reference to this paper should be made as follows: Sukmaningrum, P.S; Pirzada, K; Rusmita, S.A; Hasib, F.F; Widiastuti, T; Hendratmi, A. 2020. Determinants of Islamic Bank Profitability: Evidence from Indonesia, J. Fin. Bank. Review, 5 (1): pp. 01 – 13 https://doi.org/10.35609/jfbr.2020.5.1(1) JEL Classification: G21, G24.

Strategic determinants for introduction of innovation to the market

2019 ◽  
pp. 63-66
Author(s):  
Lyudmyla Petrenko
Keyword(s):  
Time Management ◽  
Strategic Choice ◽  
External Factors ◽  
Innovative Product ◽  
Scientific Publications ◽  
Internal Factors ◽  
Radical Innovations ◽  
Management Actions ◽  
Innovative Products ◽  
The Moment

All innovative products implemented by enterprises can be classified into two categories: radical innovation or improvements. If the first category is almost exclusively the result of breakthrough scientific research, then the second is a consequence of management actions to further improve previous innovative products. Improvements, in contrast to radical innovations, are a relatively less studied direction. In most cases, the moment the radical innovations enter the market is difficult to predict. However, the introduction of improvements to the market is determined by management. At the same time, management, making a decision on introducing an innovative product to the market, focuses on internal and external factors. Internal factors are organizational readiness to introduce an innovative product, and external factors are market necessity. The latter implies, if possible, a reaction to the actions of competitors, who also introduce innovations. The problematic question remains relevant: how do various external and internal factors determine the choice of the moment the innovation is brought to the market. What has a decisive influence on such a strategic choice? The purpose of this study was to investigate how competing and complementary technological events in the environment affect an enterprise’s launch of innovative products on the market. The study was carried out based on the analysis of scientific publications on the economics of innovation and publications on competitive rivalry. The main conclusion: strategies for improvements, as a rule, become less focused on the internal determinants of bringing innovations to the market as market concentration increases, and at the same time, they are increasingly reacting both to competitors’ innovations and innovations in additional technologies. Thus competitive pressure in the industry is an important determinant of the strategic choice to bring innovation to the market.

Sign in / Sign up

Export Citation Format

Share Document